Subjects -> MEDICAL SCIENCES (Total: 8186 journals)
    - ALLERGOLOGY AND IMMUNOLOGY (205 journals)
    - ANAESTHESIOLOGY (105 journals)
    - CARDIOVASCULAR DISEASES (334 journals)
    - CHIROPRACTIC, HOMEOPATHY, OSTEOPATHY (19 journals)
    - COMMUNICABLE DISEASES, EPIDEMIOLOGY (227 journals)
    - DENTISTRY (266 journals)
    - DERMATOLOGY AND VENEREOLOGY (162 journals)
    - EMERGENCY AND INTENSIVE CRITICAL CARE (121 journals)
    - ENDOCRINOLOGY (149 journals)
    - FORENSIC SCIENCES (43 journals)
    - GASTROENTEROLOGY AND HEPATOLOGY (178 journals)
    - GERONTOLOGY AND GERIATRICS (125 journals)
    - HEMATOLOGY (160 journals)
    - HYPNOSIS (4 journals)
    - INTERNAL MEDICINE (178 journals)
    - LABORATORY AND EXPERIMENTAL MEDICINE (90 journals)
    - MEDICAL GENETICS (58 journals)
    - MEDICAL SCIENCES (2230 journals)
    - NURSES AND NURSING (331 journals)
    - OBSTETRICS AND GYNECOLOGY (199 journals)
    - ONCOLOGY (355 journals)
    - OPHTHALMOLOGY AND OPTOMETRY (135 journals)
    - ORTHOPEDICS AND TRAUMATOLOGY (150 journals)
    - OTORHINOLARYNGOLOGY (76 journals)
    - PATHOLOGY (96 journals)
    - PEDIATRICS (254 journals)
    - PHYSICAL MEDICINE AND REHABILITATION (153 journals)
    - PSYCHIATRY AND NEUROLOGY (800 journals)
    - RADIOLOGY AND NUCLEAR MEDICINE (182 journals)
    - RESPIRATORY DISEASES (109 journals)
    - RHEUMATOLOGY (76 journals)
    - SPORTS MEDICINE (77 journals)
    - SURGERY (388 journals)
    - UROLOGY, NEPHROLOGY AND ANDROLOGY (151 journals)

HEMATOLOGY (160 journals)                     

Showing 1 - 123 of 123 Journals sorted alphabetically
Acta Angiologica     Open Access   (Followers: 3)
Adipocyte     Open Access  
Advances in Hematology     Open Access   (Followers: 13)
Africa Sanguine     Full-text available via subscription  
American Journal of Hematology     Hybrid Journal   (Followers: 46)
Anemia     Open Access   (Followers: 6)
Annals of Hematology     Hybrid Journal   (Followers: 14)
Arteriosclerosis, Thrombosis and Vascular Biology     Full-text available via subscription   (Followers: 25)
Artery Research     Hybrid Journal   (Followers: 4)
Artificial Cells, Nanomedicine and Biotechnology     Hybrid Journal   (Followers: 3)
ASAIO Journal     Hybrid Journal   (Followers: 3)
Best Practice & Research Clinical Haematology     Hybrid Journal   (Followers: 5)
Blood     Hybrid Journal   (Followers: 317)
Blood Advances     Open Access   (Followers: 9)
Blood and Lymphatic Cancer : Targets and Therapy     Open Access   (Followers: 7)
Blood Cancer Journal     Open Access   (Followers: 21)
Blood Cells, Molecules, and Diseases     Hybrid Journal   (Followers: 5)
Blood Coagulation & Fibrinolysis     Hybrid Journal   (Followers: 27)
Blood Pressure     Open Access   (Followers: 1)
Blood Pressure Monitoring     Hybrid Journal   (Followers: 2)
Blood Reviews     Hybrid Journal   (Followers: 20)
BMJ Open Diabetes Research & Care     Open Access   (Followers: 24)
Bone Marrow Transplantation     Hybrid Journal   (Followers: 15)
British Journal of Haematology     Hybrid Journal   (Followers: 54)
Canadian Journal of Diabetes     Hybrid Journal   (Followers: 9)
Case Reports in Hematology     Open Access   (Followers: 10)
Clinical and Applied Thrombosis/Hemostasis     Open Access   (Followers: 28)
Clinical Diabetes     Full-text available via subscription   (Followers: 30)
Clinical Diabetes and Endocrinology     Open Access   (Followers: 14)
Clinical Lymphoma & Myeloma     Full-text available via subscription   (Followers: 2)
Conquest : The Official Journal of Diabetes Australia     Full-text available via subscription   (Followers: 1)
Current Angiogenesis     Hybrid Journal   (Followers: 1)
Current Diabetes Reports     Hybrid Journal   (Followers: 14)
Current Diabetes Reviews     Hybrid Journal   (Followers: 13)
Current Hematologic Malignancy Reports     Hybrid Journal   (Followers: 2)
Current Opinion in Hematology     Hybrid Journal   (Followers: 14)
Cytotherapy     Full-text available via subscription   (Followers: 1)
Der Diabetologe     Hybrid Journal  
Diabetes     Full-text available via subscription   (Followers: 309)
Diabetes aktuell     Hybrid Journal   (Followers: 2)
Diabetes and Vascular Disease Research     Hybrid Journal   (Followers: 8)
Diabetes Care     Full-text available via subscription   (Followers: 314)
Diabetes Case Reports     Open Access  
Diabetes Educator     Hybrid Journal   (Followers: 10)
Diabetes Research and Clinical Practice     Hybrid Journal   (Followers: 19)
Diabetes Spectrum     Full-text available via subscription   (Followers: 14)
Diabetes Technology & Therapeutics     Hybrid Journal   (Followers: 8)
Diabetes Therapy     Open Access   (Followers: 13)
Diabetic Foot & Ankle     Open Access   (Followers: 9)
Diabetic Medicine     Hybrid Journal   (Followers: 92)
Diabetologia     Hybrid Journal   (Followers: 114)
Diabetologie und Stoffwechsel     Hybrid Journal  
Egyptian Journal of Hematology and Bone Marrow Transplantation     Open Access   (Followers: 9)
eJHaem     Open Access   (Followers: 1)
European Journal of Haematology     Hybrid Journal   (Followers: 12)
Experimental Hematology     Hybrid Journal   (Followers: 3)
Experimental Hematology & Oncology     Open Access   (Followers: 6)
Expert Review of Hematology     Hybrid Journal   (Followers: 4)
Fluids and Barriers of the CNS     Open Access   (Followers: 1)
Haematologica - the Hematology journal     Open Access   (Followers: 35)
Haemophilia     Hybrid Journal   (Followers: 15)
Hematologia     Full-text available via subscription   (Followers: 3)
Hematology     Open Access   (Followers: 9)
Hematology, Transfusion and Cell Therapy     Open Access   (Followers: 2)
Hemodialysis International     Hybrid Journal   (Followers: 3)
Hepatitis Monthly     Open Access   (Followers: 3)
Immunohematology : Journal of Blood Group Serology and Molecular Genetics     Hybrid Journal   (Followers: 3)
Indian Journal of Hematology and Blood Transfusion     Hybrid Journal   (Followers: 1)
Info Diabetologie     Full-text available via subscription  
InFo Hämatologie + Onkologie : Interdisziplinäre Fortbildung von Ärzten für Ärzte     Full-text available via subscription  
Integrated Blood Pressure Control     Open Access   (Followers: 1)
International Blood Research & Reviews     Open Access  
International Journal of Clinical Transfusion Medicine     Open Access   (Followers: 3)
International Journal of Diabetes in Developing Countries     Hybrid Journal   (Followers: 5)
International Journal of Diabetes Research     Open Access   (Followers: 6)
International Journal of Hematology     Hybrid Journal   (Followers: 3)
International Journal of Hematology Research     Open Access   (Followers: 2)
International Journal of Laboratory Hematology     Hybrid Journal   (Followers: 24)
JMIR Diabetes     Open Access  
Journal of Applied Hematology     Open Access   (Followers: 2)
Journal of Blood Medicine     Open Access  
Journal of Cerebral Blood Flow & Metabolism     Hybrid Journal   (Followers: 3)
Journal of Diabetes     Open Access   (Followers: 12)
Journal of Diabetes and its Complications     Hybrid Journal   (Followers: 13)
Journal of Diabetes and Metabolic Disorders     Open Access   (Followers: 6)
Journal of Diabetes Investigation     Open Access   (Followers: 6)
Journal of Diabetes Mellitus     Open Access   (Followers: 4)
Journal of Hematological Malignancies     Open Access  
Journal of Hematology and Transfusion Medicine     Open Access   (Followers: 1)
Journal of Hematopathology     Hybrid Journal   (Followers: 3)
Journal of Pediatric Hematology/Oncology     Hybrid Journal   (Followers: 6)
Journal of Social Health and Diabetes     Open Access  
Journal of Thrombosis and Haemostasis     Hybrid Journal   (Followers: 52)
Journal of Thrombosis and Thrombolysis     Hybrid Journal   (Followers: 30)
Leukemia     Hybrid Journal   (Followers: 23)
Leukemia and Lymphoma     Hybrid Journal   (Followers: 13)
Leukemia Research     Hybrid Journal   (Followers: 9)
Leukemia Research Reports     Open Access   (Followers: 1)
Leukemia Supplements     Full-text available via subscription  
Nederlands Tijdschrift voor Diabetologie     Hybrid Journal  
Nutrition & Diabetes     Open Access   (Followers: 18)
Oncohematology     Open Access   (Followers: 1)
Open Diabetes Journal     Open Access  
Open Hematology Journal     Open Access   (Followers: 1)
Open Hypertension Journal     Open Access  
Open Journal of Blood Diseases     Open Access  
Pediatric Blood & Cancer     Hybrid Journal   (Followers: 6)
Pediatric Hematology Oncology Journal     Open Access   (Followers: 3)
Peritoneal Dialysis International     Hybrid Journal  
Plasmatology     Open Access   (Followers: 1)
Platelets     Hybrid Journal   (Followers: 2)
Practical Diabetes     Hybrid Journal   (Followers: 4)
Primary Care Diabetes     Hybrid Journal   (Followers: 16)
Research and Practice in Thrombosis and Haemostasis     Open Access   (Followers: 2)
Revista Cubana de Hematología, Inmunología y Hemoterapia     Open Access  
Seminars in Hematology     Hybrid Journal   (Followers: 9)
Seminars in Thrombosis and Hemostasis     Hybrid Journal   (Followers: 28)
The Lancet Haematology     Full-text available via subscription   (Followers: 43)
Therapeutic Advances in Hematology     Hybrid Journal  
Thrombosis & Haemostasis     Hybrid Journal   (Followers: 105)
Thrombosis Research     Hybrid Journal   (Followers: 30)
Transplantation and Cellular Therapy     Hybrid Journal   (Followers: 11)
Veins and Lymphatics     Open Access   (Followers: 1)

           

Similar Journals
Journal Cover
Journal of Applied Hematology
Number of Followers: 2  

  This is an Open Access Journal Open Access journal
ISSN (Print) 1658-5127 - ISSN (Online) 2454-6976
Published by Medknow Publishers Homepage  [444 journals]
  • Aerospace, Vol. 11, Pages 601: Research on the Design of Aviation and
           Aerospace Hatch Door Mechanisms and Their Future Bionic Prospects

    • Authors: Zhiwu Cui, Haochang Wu, Ming Zhou, Zhihe Cui, Hao Huang, Ziyu Liu
      First page: 601
      Abstract: The design of the space hatch door mechanisms is crucial in the aerospace field, impacting not only durability and reliability but also the life safety of astronauts during space missions. This review extensively researches vehicle doors and hatches in civil and military systems across various environments, including land, sea, deep sea, aviation, aerospace, and extreme conditions. Specially, it focuses on the structural design of hatches and related mechanisms in civil aviation and military aerospace environments, such as opening and closing mechanisms, release mechanisms, locking mechanisms, sealing mechanisms, and the ergonomic design of door structures. The review highlights the integration of bionic design principles with hatch mechanisms to explore future solutions. By systematically examining these aeras, this review addresses the lack of comprehensive studies in previous reviews, which often overlook the interconnectivity and applicability of hatch mechanisms across different fields. The absence of such holistic reviews has led to fragmented knowledge and missed opportunities for cross-industry innovation. This review aims to fill these gaps by providing a wide range of design solutions and offering insights that can enhance the development of more reliable, efficient, and safe hatch mechanisms in aerospace and other high-stakes environments.
      Citation: Aerospace
      PubDate: 2024-07-23
      DOI: 10.3390/aerospace11080601
      Issue No: Vol. 11, No. 8 (2024)
       
  • Aerospace, Vol. 11, Pages 602: Flow-Based Assessment of the Impact of an
           All-Electric Aircraft on European Air Traffic

    • Authors: Bekir Yildiz, Peter Förster, Thomas Feuerle, Peter Hecker
      First page: 602
      Abstract: The consequences of new airspace entrants, such as novel aircraft concepts with innovative propulsion systems, on air traffic management operations need to be carefully identified. This paper aims to assess the impact of future aircraft with different performance envelopes on the European air traffic network from a flow-based perspective. The underlying approach assumes that all certification-related questions concerning airworthiness have been resolved and do not take into account any economic factors related to airline operations. For example, for an innovative propulsion system, a short range all-electric aircraft is considered in this study. Aircraft trajectory calculations are based on the dataset of base of aircraft data (BADA), which are developed and maintained by EUROCONTROL. The new design concept is integrated into BADA as well, resulting in a new set of coefficients for the all-electric aircraft. In addition to the adjusted parameters which affect airborne performances, ground-related aspects are also taken into account. This includes assumptions on operational procedures, charging capacities and adaptions in infrastructure. Investigations are carried out at the trajectory level as well as at the airport and the entire network.
      Citation: Aerospace
      PubDate: 2024-07-23
      DOI: 10.3390/aerospace11080602
      Issue No: Vol. 11, No. 8 (2024)
       
  • Aerospace, Vol. 11, Pages 603: Application of High-Speed Self-Aligned
           Focusing Schlieren System for Supersonic Flow Velocimetry

    • Authors: Philip A. Lax, Sergey B. Leonov
      First page: 603
      Abstract: A self-aligned focusing schlieren (SAFS) system combines the field of view of a conventional schlieren system with the defocus blur of a focusing schlieren system away from the object plane. It can be assembled in a compact form, measuring 1.2 m (4 ft) in length in the described case. The depth of field is sufficiently shallow to distinguish specific spanwise features in a supersonic flow field within a 76.2 mm (3 in) wide test section. As a result, the boundary-layer perturbations on windows and window-material defects and surface imperfections are blurred. Analytical forms are derived for depth of field and vignetting of the SAFS system. A laser spark velocity measurement in Mach 2 flow is performed by tracking the blast wave of a laser spark using 500 kHz SAFS imaging with a 200 ns optical pulse width. The flow Mach number and stagnation temperature are measured by comparing the blast-wave dynamics to an analytical solution. Additionally, schlieren image velocimetry is performed by analyzing natural flow perturbations in 500 kHz SAFS images using a self-correlation method. Comparing the spectra of gas density perturbations from the core flow and a near-wall region reveals a significant difference, with high-frequency prevalence at the boundary-layer location.
      Citation: Aerospace
      PubDate: 2024-07-24
      DOI: 10.3390/aerospace11080603
      Issue No: Vol. 11, No. 8 (2024)
       
  • Aerospace, Vol. 11, Pages 604: Arrival and Departure Sequencing,
           Considering Runway Assignment Preferences and Crossings

    • Authors: Ji Ma, Daniel Delahaye, Man Liang
      First page: 604
      Abstract: Aircraft sequencing has the potential to decrease flight delays and improve operational efficiency at airports. This paper presents the aircraft sequencing problem (ASP) on multiple runways with complex interactions by allocating flights on runways and optimizing landing times, take-off times, and crossing times simultaneously in a uniform framework. The problem was formulated as a mixed-integer program considering realistic operational constraints, including runway assignment preferences based on the entry/exit fixes of the terminal maneuvering area (TMA), minimum runway separation, time window, and arrival crossing rules. Variable-fixing strategies were applied, to strengthen the formulation. A first-come-first-served (FCFS) heuristic was proposed for comparison. Various instances from the literature and from realistic data sets were tested. Our computational study showed that the solution approach optimizes runway schedules, to achieve significantly fewer flight delays, taking runway assignment preferences and arrival crossings into account.
      Citation: Aerospace
      PubDate: 2024-07-24
      DOI: 10.3390/aerospace11080604
      Issue No: Vol. 11, No. 8 (2024)
       
  • Aerospace, Vol. 11, Pages 605: SE-CBAM-YOLOv7: An Improved Lightweight
           Attention Mechanism-Based YOLOv7 for Real-Time Detection of Small Aircraft
           Targets in Microsatellite Remote Sensing Imaging

    • Authors: Zhenping Kang, Yurong Liao, Shuhan Du, Haonan Li, Zhaoming Li
      First page: 605
      Abstract: Addressing real-time aircraft target detection in microsatellite-based visible light remote sensing video imaging requires considering the limitations of imaging payload resolution, complex ground backgrounds, and the relative positional changes between the platform and aircraft. These factors lead to multi-scale variations in aircraft targets, making high-precision real-time detection of small targets in complex backgrounds a significant challenge for detection algorithms. Hence, this paper introduces a real-time aircraft target detection algorithm for remote sensing imaging using an improved lightweight attention mechanism that relies on the You Only Look Once version 7 (YOLOv7) framework (SE-CBAM-YOLOv7). The proposed algorithm replaces the standard convolution (Conv) with a lightweight convolutional squeeze-and-excitation convolution (SEConv) to reduce the computational parameters and accelerate the detection process of small aircraft targets, thus enhancing real-time onboard processing capabilities. In addition, the SEConv-based spatial pyramid pooling and connected spatial pyramid convolution (SPPCSPC) module extracts image features. It improves detection accuracy while the feature fusion section integrates the convolutional block attention module (CBAM) hybrid attention network, forming the convolutional block attention module Concat (CBAMCAT) module. Furthermore, it optimizes small aircraft target features in channel and spatial dimensions, improving the model’s feature fusion capabilities. Experiments on public remote sensing datasets reveal that the proposed SE-CBAM-YOLOv7 improves detection accuracy by 0.5% and the mAP value by 1.7% compared to YOLOv7, significantly enhancing the detection capability for small-sized aircraft targets in satellite remote sensing imaging.
      Citation: Aerospace
      PubDate: 2024-07-24
      DOI: 10.3390/aerospace11080605
      Issue No: Vol. 11, No. 8 (2024)
       
  • Aerospace, Vol. 11, Pages 606: Influence of Double-Ducted Serpentine
           Nozzle Configurations on the Interaction Characteristics between the
           External and Nozzle Flow of Aircraft

    • Authors: Jilong Zhu, Yi Zhang, Yaohua Li, Liquan Zeng, Lei Miao, Neng Xiong, Yang Tao
      First page: 606
      Abstract: To clarify the influence of the serpentine nozzle configurations on the flow characteristics and aerodynamic performance of aircraft, the flow features and aerodynamic performances of the double-ducted serpentine nozzles with different aspect ratios (AR), length–diameter ratios (LDR) and shielding ratios (SR) are numerically investigated. The results show that the asymmetric nozzle flow occurs due to the curved profile of serpentine nozzles, and a local accelerating effect exists at the S-bend, causing the increase in wall shear stress. The unilateral unsymmetrical expansion of the tail jet in the upward direction interacts with the separated external flow of the afterbody, forming an obvious cross-shock wave and shear layer structure. The surface pressure of the afterbody increases along the external flow direction, and decreases sharply in the separation point of the boundary layer. With the increase in AR and LDR, the local accelerating effect of the nozzle flow weakens, while with the increase in SR, the accelerating effect increases. The total pressure recovery coefficient, flow coefficient and axial thrust coefficient all decrease with the increase in AR, LDR, and SR. The thrust vector angle decreases with the increase in AR but is less affected by LDR and SR.
      Citation: Aerospace
      PubDate: 2024-07-24
      DOI: 10.3390/aerospace11080606
      Issue No: Vol. 11, No. 8 (2024)
       
  • Aerospace, Vol. 11, Pages 607: Nonlinear Surrogate Model Design for
           Aerodynamic Dataset Generation Based on Artificial Neural Networks

    • Authors: Guillermo Suarez, Emre Özkaya, Nicolas R. Gauger, Hans-Jörg Steiner, Michael Schäfer, David Naumann
      First page: 607
      Abstract: In this work we construct a surrogate model using artificial neural networks (ANN) to predict the steady-state behavior of an unmanned combat aircraft. We employ various strategies to improve the model’s accuracy, including the consideration of design tolerances, creating independent surrogate models for the different flow regimes and encoding non-numeric input features. We also explore alternative machine learning models, albeit they demonstrated a lower reliability than ANNs. Two scenarios are considered for the target variable: one focusing solely on predicting the pitching moment coefficient, and the other incorporating the roll moment coefficient as well. We investigate different methods for handling multiple targets, finding that constructing a single model with multiple outputs consistently outperforms developing separate models for each target variable. Overall, the ANN provides predictions that show excellent agreement with the experimental data, demonstrating its effectiveness and reliability in aerodynamic modeling.
      Citation: Aerospace
      PubDate: 2024-07-24
      DOI: 10.3390/aerospace11080607
      Issue No: Vol. 11, No. 8 (2024)
       
  • Aerospace, Vol. 11, Pages 608: Analysis and Evaluation of Fault
           Propagation Behavior in Integrated Avionics Systems Considering Cascading
           Failures

    • Authors: Lei Dong, Bo Peng, Xi Chen, Jiachen Liu
      First page: 608
      Abstract: As the synthesis, modularization, and integration of avionics systems increase, the interconnections between systems and equipment within subsystems become increasingly complex, posing risks to the safety and reliability of the integrated avionics system. To address the risk of fault propagation due to functional cascade failures in integrated avionics systems, this paper proposes a discrete dynamic fault propagation analysis method, which was applied to an all-electric braking system to assess its feasibility. First, the architectural features of the Distributed Integrated Modular Avionics system are summarized. Subsequently, the constructed system layer model is described, establishing the function–resource hierarchical architecture. Subsequently, the behavior of cascading failure propagation in discrete dynamic systems is analyzed by integrating the cascading failure analysis method from SAE ARP 4761A and considering the coupling characteristics between system properties and functions comprehensively. This approach facilitates the development of a cascading failure propagation model for DIMA based on discrete dynamic systems. Finally, by using the all-electric braking system under DIMA architecture as a case study, key Core Processing Modules and failure-prone functions are identified. The findings reveal that within this system, CPM2 and CPM6 are particularly susceptible to failure propagation, and the automatic brake function is notably vulnerable. Data show that the system’s failure rate escalates markedly after 2×104 h of operation. Performing maintenance before reaching this threshold can further mitigate risks. This practice aligns with current international aircraft maintenance time regulations. The method proposed in this paper can be applied early in the allocation of DIMA resources to enhance security and support DIMA design.
      Citation: Aerospace
      PubDate: 2024-07-25
      DOI: 10.3390/aerospace11080608
      Issue No: Vol. 11, No. 8 (2024)
       
  • Aerospace, Vol. 11, Pages 609: Restrain Performance of Child Restraint
           Systems for 1.5-Year-Old Children on Commercial Airplanes: An Experimental
           Study

    • Authors: Xiaopeng Shi, Yifan Zhou, Chen Xiong, Yafeng Wang, Yonglong He, Zhenyu Feng, Jiang Xie
      First page: 609
      Abstract: This study aims to compare the restraint performance of two child restraint systems (CRSs) used on airplanes—a rear-facing child seat (RFCS) and the child aviation restraint system (CARES)—for 1.5-year-old children, along with their compatibility with different types of aircraft seats. 16 g longitudinal dynamic tests were conducted on two types of aircraft seats with CRSs. Results indicate poor compatibility of CARES with Type A seats, significantly increasing the risk of head, neck, and abdominal injuries, with Nij exceeding the acceptable limit. In contrast, CARES exhibited good compatibility with Type B seats and effectively protected children. RFCS tests demonstrated effective injury risk reduction on both types of seats. It can be found that the performance of CARES depends on restraint status and seat dimensions; RFCSs provide adequate protection for 1.5-year-olds. Optimal protection can be achieved with smaller restrain angles of CRS and using thinner seat cushions. Compared to CARES, RFCSs better adapt to various aircraft seat structures, offering superior child protection.
      Citation: Aerospace
      PubDate: 2024-07-25
      DOI: 10.3390/aerospace11080609
      Issue No: Vol. 11, No. 8 (2024)
       
  • Aerospace, Vol. 11, Pages 610: Fuzzy Control for Aircraft Engine: Dynamics
           Clustering Modeling, Compensation and Hardware-in-Loop Experimental
           Verification

    • Authors: Muxuan Pan, Hao Wang, Chenchen Zhang, Yun Xu
      First page: 610
      Abstract: This paper presents an integrated framework for aircraft engines, which consists of three phases: modeling, control, and experimental testing. The engine is formulated as an uncertain T–S fuzzy model. By a hierarchical dynamical parameter clustering, the number and premise variables of fuzzy rules are optimized, which keeps the engine’s prime and representative dynamics. For each fuzzy rule, a global stability-guaranteed method is developed for the identification of the consequent uncertain dynamic model. The resulting stable T–S fuzzy model accurately approximates the actual engine dynamics in the operation space. Based on this fuzzy model, a new robust control is constructed with hierarchical compensators. The control parameters take advantage of the fuzzy blend of engine prime dynamics and uncertainty thresholds. Extensive hardware-in-loop (HIL) experimental tests in the flight envelope and a flight task cycle demonstrate the effectiveness and real-time performance of the proposed control. The settling times and overshoots of engine response are suppressed to be under 2.5 s and 10%, respectively.
      Citation: Aerospace
      PubDate: 2024-07-25
      DOI: 10.3390/aerospace11080610
      Issue No: Vol. 11, No. 8 (2024)
       
  • Aerospace, Vol. 11, Pages 611: Numerical Analysis of the Water Entry
           Process of the Cabin Structure of the Trans-Domain Morphing Aircraft
           Considering Structural Deformation

    • Authors: Yu Zhang, Ziyi He, Chen Wang, Qi Hu, Songwen Dong, Xing Shen, Jun Zhang, Taoxi Wang
      First page: 611
      Abstract: During the water entry process of a trans-domain morphing aircraft, significant impact forces are generated when the aircraft hits the water surface, which will potentially cause the deformation of the cabin structure and might damage the structure or onboard devices. Thus, it is necessary to investigate the water entry process of the cabin structure. This paper analyses changes in fluid loads and the corresponding structural responses during the water entry process. Firstly, the numerical model is established for the water entry process and the modeling method is validated by comparing the results to the experimental data. An empirical formula is developed to correlate the impact loads with the water entry velocities. Then, fluid–structure interaction analysis of the water entry process is performed using a two-way coupling approach. The relationship between structural deformation and the water entry process is then investigated. The results are compared with those without considering the structural deformation. The empirical formula is then modified to reflect the effects of the deformation. The results show that structural deformation will disperse the impact load, which represents different responses compared to the rigid cabin structure.
      Citation: Aerospace
      PubDate: 2024-07-25
      DOI: 10.3390/aerospace11080611
      Issue No: Vol. 11, No. 8 (2024)
       
  • Aerospace, Vol. 11, Pages 612: Leader-Following Connectivity Preservation
           and Collision Avoidance Control for Multiple Spacecraft with Bounded
           Actuation

    • Authors: Xianghong Xue, Xin Wang, Nannan Han
      First page: 612
      Abstract: This paper investigates the distributed formation control of a group of leader-following spacecraft with bounded actuation and limited communication ranges. In particular, connectivity-preserving and collision-avoidance controllers are proposed for the leader with constant or time-varying velocity, respectively. The communication graph between the spacecraft is modeled via a distance-induced proximity graph. By designing a virtual proxy for each spacecraft, the spacecraft–proxy couplings address the actuator saturation constraints. The inter-proxy dynamics incorporated with a bounded artificial potential function fulfill the coordination of all proxies. In addition, the bounded potential function can simultaneously tackle connectivity preservation and collision avoidance problems. The distributed formation controllers are proposed for multiple spacecraft with constant or time-varying velocities relative to the leader. A sliding mode control approach and the proxies’ dynamics are used in the design of a distributed cooperative controller for spacecraft to address the cooperative problem between the followers and the leader. Numerical simulations confirm the effectiveness of the anti-saturation distributed connectivity preservation controller.
      Citation: Aerospace
      PubDate: 2024-07-26
      DOI: 10.3390/aerospace11080612
      Issue No: Vol. 11, No. 8 (2024)
       
  • Aerospace, Vol. 11, Pages 613: Advancing the Diagnosis of Aero-Engine
           Bearing Faults with Rotational Spectrum and Scale-Aware Robust Network

    • Authors: Jin Li, Zhengbing Yang, Xiang Zhou, Chenchen Song, Yafeng Wu
      First page: 613
      Abstract: The precise monitoring of bearings is crucial for the timely detection of issues in rotating mechanical systems. However, the high complexity of the structures makes the paths of vibration signal transmission exceedingly intricate, posing significant challenges in diagnosing aero-engine bearing faults. Therefore, a Rotational-Spectrum-informed Scale-aware Robustness (RSSR) neural network is proposed in this study to address intricate fault characteristics and significant noise interference. The RSSR algorithm amalgamates a scale-aware feature extraction block, a non-activation convolutional network, and an innovative channel attention block, striking a balance between simplicity and efficacy. We provide a comprehensive analysis by comparing traditional CNNs, transformers, and their respective variants. Our strategy not only elevates diagnostic precision but also judiciously moderates the network’s parameter count and computational intensity, mitigating the propensity for overfitting. To assess the efficacy of our proposed network, we performed rigorous testing using two complex, publicly available datasets, with additional artificial noise introductions to simulate challenging operational environments. On the noise-free dataset, our technique increased the accuracy by 5.11% on the aero-engine dataset compared with the current mainstream methods. Even under maximal noise conditions, it enhances the average accuracy by 4.49% compared with other contemporary approaches. The results demonstrate that our approach outperforms other techniques in terms of diagnostic performance and generalization ability.
      Citation: Aerospace
      PubDate: 2024-07-26
      DOI: 10.3390/aerospace11080613
      Issue No: Vol. 11, No. 8 (2024)
       
  • Aerospace, Vol. 11, Pages 614: Twist Angle Error Statistical Analysis and
           Uncertain Influence on Aerodynamic Performance of Three-Dimensional
           Compressor Rotor

    • Authors: Yue Dan, Ruiyu Li, Limin Gao, Huawei Yu, Yuyang Hao
      First page: 614
      Abstract: Twist angle errors along the blade radial direction are uncertain and affected by cutting force, tool wear, and other factors. In this paper, the measured twist angle errors of 13 sections of 72 rotor blades were innovatively analyzed to obtain the rational statistical distribution. It is surprisingly found that the under-deflection systematic deviation of twist angle errors shows a gradually increasing W-shaped distribution along the radial direction, while the scatter is nearly linear. Logically, the statistical model is established based on the linear correlation of the scatter by regression analysis to reduce variable dimension from 13 to 1. The influence of the radial non-uniform twist angle errors’ uncertainty on the aerodynamic performance of the three-dimensional compressor rotor is efficiently quantified combining the non-intrusive polynomial chaos method. The results show that the mean values of mass flow rate, total pressure ratio, and isentropic efficiency at the typical operating conditions are lower than the nominal values due to the systematic deviation, indicating that the under-deflection twist angle errors lead to the decrease in compressor thrust. The compressor’s stable operating range is more sensitive to the scatter of twist angle errors, which is up to an order of magnitude greater than that of the total pressure ratio and isentropic efficiency, indicating the compressor’s safe and stable operation risk increases. Additionally, the flow field at the tip region is significantly affected by twist angle errors, especially at the shock wave position of the near-stall condition.
      Citation: Aerospace
      PubDate: 2024-07-26
      DOI: 10.3390/aerospace11080614
      Issue No: Vol. 11, No. 8 (2024)
       
  • Aerospace, Vol. 11, Pages 615: Spectral Properties of Bistatic Radar
           Signals Using the Ray Tracing Technique and a Facet Approach

    • Authors: Mingcheng Zuo, Rukiah S. Mitri, Igor Gai, Giancorrado Brighi, Paolo Tortora
      First page: 615
      Abstract: Bistatic radar experiments have been used to study surface characteristics of extra-terrestrial bodies in the Solar System, including the Moon, Venus, Mars, and Titan. This paper proposes a 3D model to characterize the scattered field of a gaussian rough surface on an extra-terrestrial body for an orbital bistatic radar configuration. Specifically, this model will investigate how the variability of surface roughness impacts the spectral broadening of the received signal using physical optics approximations and ray tracing on a surface model using a facet approach with Gaussian properties. A linear relationship between spectral broadening of the signal and surface roughness was found. This relationship is in line with results obtained by commonly used analytical models for bistatic radar on planetary surfaces.
      Citation: Aerospace
      PubDate: 2024-07-26
      DOI: 10.3390/aerospace11080615
      Issue No: Vol. 11, No. 8 (2024)
       
  • Aerospace, Vol. 11, Pages 616: A Comparative Study on the Efficiencies of
           

    • Authors: Özge Özkaya Yılmaz, Altan Kayran
      First page: 616
      Abstract: This paper presents the effect of wing elasticity on the efficiency of a nonintrusive reduced order model using a three-dimensional sweptback wing. For this purpose, a computationally low-cost but highly accurate nonintrusive reduced order method is constructed utilizing proper orthogonal decomposition (POD) coupled with radial basis function (RBF) interpolation. The results are evaluated in terms of order reduction and prediction capability of rigid and aeroelastic ROMs. Our results show that compared to the rigid wing, reduced order modeling is more effectively applied to the aeroelastic sweptback wing due to the postponement of flow separation caused by bending–torsion coupling, when the pressure coefficient (Cp) is considered as the output. We further show that for flexible wings, utilizing rigid nodes is not sufficient for presenting the Cp distribution accurately; hence, separate ROMs must be generated for the deformed positions of the nodes. Moreover, the RBF method is also exploited for prediction of the results with direct interpolation of the data ensemble by generating a surrogate model. Finally, the proposed methods are compared in terms of accuracy, computational cost and practicality.
      Citation: Aerospace
      PubDate: 2024-07-27
      DOI: 10.3390/aerospace11080616
      Issue No: Vol. 11, No. 8 (2024)
       
  • Aerospace, Vol. 11, Pages 617: Position Calculation for Front Fin of
           Rocket Forebody Using Variable Step Scheme

    • Authors: Zeyang Zhou, Jun Huang
      First page: 617
      Abstract: In order to determine the installation position of the front fin on the example rocket forebody, an optimized method based on a comprehensive evaluation indicator and variable step search is presented. The comprehensive indicator consists of four weight coefficients, two lateral aerodynamic forces and two aerodynamic moments. The computational fluid dynamics method based on a shear stress transport turbulence model is established to analyze the flow field characteristics of the forebody. The results indicate that under equal weight coefficients, the presented search algorithm can provide an optimized solution for the front fin to achieve the minimum value of the comprehensive evaluation indicator. When the range of the current wing movement changes or the weight coefficient distribution changes, this search algorithm can still provide the optimal solution and some feasible solutions. Under the given conditions, there is a difference between the optimal solution of the aerodynamic force priority and that of the aerodynamic moment priority. For the case of the aerodynamic moment priority, the mean level of the pressure coefficient corresponding to the optimal solution on the given observation plane is low. The presented method is effective in learning the appropriate installation position of the rocket’s front fins.
      Citation: Aerospace
      PubDate: 2024-07-27
      DOI: 10.3390/aerospace11080617
      Issue No: Vol. 11, No. 8 (2024)
       
  • Aerospace, Vol. 11, Pages 618: Wind Tunnel Experiment and Numerical
           Simulation of Secondary Flow Systems on a Supersonic Wing

    • Authors: Sheng Zhang, Zheng Lin, Zeming Gao, Shuai Miao, Jun Li, Lifang Zeng, Dingyi Pan
      First page: 618
      Abstract: Aircraft secondary flow systems are small-flow circulation devices that are used for thermal and cold management, flow control, and energy generation on aircraft. The aerodynamic characteristics of main-flow-based inlets have been widely studied, but the secondary-flow-based small inlets, jets, and blowing and suction devices have seldom been studied. Two types of secondary flow systems embedded in a supersonic aircraft wing, a ram-air intake and a submerged intake, are researched here. Firstly, wind tunnel tests under subsonic, transonic, and supersonic conditions are carried out to test the total pressure recovery and total pressure distortion. Secondly, numerical simulations are used to analyze the flow characteristics in the secondary flow systems. The numerical results are validated with experimental data. The calculating errors of the total pressure recovery on the ram-air and submerged secondary flow systems are 8% and 10%, respectively. The simulation results demonstrate that the total pressure distortion tends to grow while the total pressure recovery drops with the increasing Mach number. As the Mach number increases from 0.4 to 2, the total pressure recovery of the ram-air secondary flow system decreases by 68% and 71% for the submerged system. Moreover, the total pressure distortion of the ram-air and submerged secondary flow systems is increased by 19.7 times and 8.3 times, respectively. Thirdly, a detailed flow mechanism is studied based on the simulation method. It is found that the flow separation at the front part of the tube is induced by adverse pressure gradients, which primarily determine the total pressure recovery at the outlet. The three-dimensional vortex in the tube is mainly caused by the change in cross-sectional shape, which influences the total pressure distortion.
      Citation: Aerospace
      PubDate: 2024-07-28
      DOI: 10.3390/aerospace11080618
      Issue No: Vol. 11, No. 8 (2024)
       
  • Aerospace, Vol. 11, Pages 619: Identification of Key Nodes in Multi-Layer
           Heterogeneous Aviation Network through Aggregating Multi-Source
           Information

    • Authors: Qi Gao, Minghua Hu, Lei Yang, Zheng Zhao
      First page: 619
      Abstract: Aviation networks exhibit multi-layer characteristics and heterogeneity of nodes and edges. Identifying key nodes in a multi-layer heterogeneous aviation network (MHAN) and elucidating its cascading failure process are of great practical significance for enhancing the ability to resist failure and strengthening network resilience. Therefore, this paper first establishes the basic model of MHAN and then designs an intra-layer node importance evaluation method based on the improved TOPSIS-grey correlation analysis (ITG) method and an inter-layer influence weight quantification method based on the gravity model. By integrating the information transmission characteristics between network nodes, a key node identification method in MHAN through aggregating multi-source information is proposed. Finally, based on the actual overload operation of aviation networks, the initial load adjustment coefficient, capacity limit, and overload coefficient are introduced based on the traditional capacity–load model, a cascading failure model of MHAN considering overload condition and failure probability is constructed, and a node influence index based on this model is defined to verify the accuracy of the key node identification results. The instance analysis conducted on the aviation network in western China demonstrates that the intra-layer node importance evaluation method based on ITG yields results with better distinguishability and higher accuracy. The key nodes are predominantly hub en-route nodes and sector nodes. In the cascading failure model, increasing the overload coefficient and capacity limit within a specific range while reducing the initial load adjustment coefficient helps reduce the network failure scale. The key nodes identified by the node influence index are consistent with those identified by the method proposed in this paper, validating the accuracy and effectiveness of the key node identification method in MHAN through aggregating multi-source information herein.
      Citation: Aerospace
      PubDate: 2024-07-29
      DOI: 10.3390/aerospace11080619
      Issue No: Vol. 11, No. 8 (2024)
       
  • Aerospace, Vol. 11, Pages 620: Experimental Parameter Identification and
           an Evaluation of the Impact of Tire Models on the Dynamics of Fixed-Wing
           Unmanned Aerial Vehicles

    • Authors: Hikaru Eguchi, Daisuke Nakata
      First page: 620
      Abstract: Because fixed-wing unmanned aerial vehicles (UAVs) require high-speed taxiing for takeoff and landing, the aircraft’s stability during taxiing is critical. However, despite research on the taxiing stability of fixed-wing UAVs conducted in taxiing motion simulations employing various tire models, the applicability of the models to fixed-wing UAV taxiing simulations remains unclear, as does the rationale behind the parameter settings in the models. Therefore, in our study, we measured the forces acting on the tires of a fixed-wing UAV under various conditions, including tire loads of 1.6–3.6 kg and tire slip angles of 0–40 deg. Based on the results, we modified conventional tire models and assessed their applicability in taxiing simulations. Among our findings, the parameter values of the models significantly differed from those used in crewed aircraft taxiing simulations, and the presence or absence of load parameters in the lateral force tire models significantly affected the dynamics. Furthermore, the aerodynamics acting on the aircraft enhanced the straight-line stability during taxiing, resulting in reduced forces on the tires.
      Citation: Aerospace
      PubDate: 2024-07-29
      DOI: 10.3390/aerospace11080620
      Issue No: Vol. 11, No. 8 (2024)
       
  • Aerospace, Vol. 11, Pages 621: Experimental and Numerical Simulation of
           Ejecta Size and Velocity of Hypervelocity Impact Rubble-Pile Asteroid

    • Authors: Wenjin Liu, Qingming Zhang, Renrong Long, Jiankang Ren, Juncheng Li, Zizheng Gong, Qiang Wu, Siyuan Ren
      First page: 621
      Abstract: Rubble-pile asteroids may be the type of near-Earth object most likely to threaten Earth in a future collision event. Small-scale impact experiments and numerical simulations for large-scale impacts were conducted to clarify the size ratio of the boulder/projectile diameter effects on ejecta size–velocity distribution. A series of small-scale impact cratering experiments were performed on porous gypsum–basalt targets at velocities of 2.3 to 5.5 km·s−1. Three successive ejection processes were observed by high-speed and ultra-high-speed cameras. The momentum transfer coefficient and cratering size were measured. A three-dimensional numerical model reflecting the random distribution of the interior boulders of the rubble-pile structure asteroid is established. The size ratio (length to diameter) of the boulder size inside the asteroid to the projectile diameter changed from 0.25 to 1.7. We conducted a smoothed particle hydrodynamics numerical simulation in the AUTODYN software to study the boulder size effect on the ejecta size–velocity distribution. Simulation results suggest that the microscopic porosity on regolith affects the propagation of shock waves and reduces the velocity of ejecta. Experiments and numerical simulation results suggest that both excavation flow and spalling ejection mechanism can eject boulders (0.12–0.72 m) out of the rubble-pile asteroid. These experiments and simulation results help us select the potential impact site in a planetary defense scenario and reduce deflection risk. are comprised primarily of boulders of a range of sizes.
      Citation: Aerospace
      PubDate: 2024-07-29
      DOI: 10.3390/aerospace11080621
      Issue No: Vol. 11, No. 8 (2024)
       
  • Aerospace, Vol. 11, Pages 622: Theoretical Investigation of Laser Ablation
           Propulsion Using Micro-Scale Fluid in Atmosphere

    • Authors: Chentao Mao, Luyun Jiang, Baosheng Du, Yongzan Zheng, Haichao Cui, Diankai Wang, Jifei Ye, Jianhui Han, Yanji Hong
      First page: 622
      Abstract: Laser ablation propulsion based on liquid propellants is a type of propulsion technology with a high specific impulse and good controllability that can be applied to space thrusters, gas metal arc welding, and extreme ultraviolet light. However, its basic mechanisms, such as flow evolution and thrust formation, have not yet been described in detail. In this study, the laser ablation of micro-scale fluid in the atmosphere was investigated. Flow evolution with different laser energy and fluid mass was observed using a schlieren system. According to the characteristic of flow evolution, a theoretical model of laser ablation propulsion in the atmosphere was established. For the first time, a theoretical hypothesis was proposed that the laser energy is divided into two parts, which act on fluid and air respectively. The model indicates that the impulses generated by fluids and air follow power laws with the laser energy, while the exponentials are 0.5 and 1, respectively. In the atmosphere, due to the shielding effect of a laser-maintained detonation wave on laser, the energy absorbed by the fluid is basically unchanged, while only the energy absorbed by the air changes. Significantly, the theoretical model is consistent with the impulse experiment and current studies.
      Citation: Aerospace
      PubDate: 2024-07-30
      DOI: 10.3390/aerospace11080622
      Issue No: Vol. 11, No. 8 (2024)
       
  • Aerospace, Vol. 11, Pages 623: A Frequency Domain PID Control Strategy for
           an In-House Friction and Wear Test Rig

    • Authors: Di Li, Jing Wang, Hongguang Li, Guang Meng, Anlue Li
      First page: 623
      Abstract: The contact behavior greatly influences the damping performance of frictional interfaces. Numerous experimental studies on friction and fretting wear have investigated the evolution of contact parameters. An in-house friction and wear test rig has been developed to obtain hysteresis loops at certain normal forces. However, the test rig lacks load control and is thus unable to ensure precise stabilization at a preset normal force, which affected the hysteresis behavior. In this paper, we developed a frequency-domain PID controller to ensure the stable application of a target normal force with constant (0–300 N) and harmonic (0–50 N) components. Compared to the commonly used time-domain strategy, the control signal error is reduced from 6.30% to 0.54% at 50 Hz. With a 3% error as the standard, the controller enables stabilized control of signals with frequencies up to 300 Hz. Friction experiments on various typical materials are conducted using this improved test rig. The results indicate a general tendency for contact stiffness to increase with a rising normal force, while the relationship between the friction coefficient and the normal force does not exhibit a clear pattern. The contact stiffness is not sensitive to the relative displacement or vibration frequency.
      Citation: Aerospace
      PubDate: 2024-07-30
      DOI: 10.3390/aerospace11080623
      Issue No: Vol. 11, No. 8 (2024)
       
  • Aerospace, Vol. 11, Pages 624: Ballistic Limit Equation Derivation for
           Thin Tape Tethers

    • Authors: Lorenzo Olivieri, Cinzia Giacomuzzo, Alessandro Francesconi
      First page: 624
      Abstract: Electromagnetic tethers of hundreds or thousands of meters have been proposed for maneuvring spacecraft in Low Earth Orbit, and in particular, for post-mission disposals. The debate on tether survivability to debris impact is still influencing further advances in the implementation of such technology because of the large area they expose to the debris environment; thin tape geometries have been proposed instead of round ones to increase the survivability to hypervelocity impacts. In this context, this paper introduces a new Ballistic Limit Equation (BLE) for thin tape tethers, derived from experimental results, numerical simulations, and literature data. The resulting equation is non-monotonic with respect to impact angle, presenting a minimum depending on the debris velocity and size; for high obliquities, the debris fragmentation triggered by shock waves propagating into the material reduces the damage. This feature allows to set a minimum particle diameter for risk assessment, excluding a significant part of the debris flux. The proposed BLE confirms the performance of thin tape tethers, with respect to round wires, due to their better ballistic response as well as their reduced cross-section at high-obliquity impacts.
      Citation: Aerospace
      PubDate: 2024-07-30
      DOI: 10.3390/aerospace11080624
      Issue No: Vol. 11, No. 8 (2024)
       
  • Aerospace, Vol. 11, Pages 625: Bidirectional Long Short-Term Memory
           Development for Aircraft Trajectory Prediction Applications to the UAS-S4
           Ehécatl

    • Authors: Seyed Mohammad Hashemi, Ruxandra Mihaela Botez, Georges Ghazi
      First page: 625
      Abstract: The rapid advancement of unmanned aerial systems in various civilian roles necessitates improved safety measures during their operation. A key aspect of enhancing safety is effective collision avoidance, which is based on conflict detection and is greatly aided by accurate trajectory prediction. This paper represents a novel data-driven trajectory prediction methodology based on applying the Long Short-Term Memory (LSTM) prediction algorithm to the UAS-S4 Ehécatl. An LSTM model was designed as the baseline and then developed into a Staked LSTM to better capture complex and hierarchical temporal trajectory patterns. Next, the Bidirectional LSTM was developed for a better understanding of the contextual trajectories from both its past and future data points, and to provide a more comprehensive temporal perspective that could enhance its accuracy. LSTM-based models were evaluated in terms of mean absolute percentage errors. The results reveal the superiority of the Bidirectional LSTM, as it could predict UAS-S4 trajectories more accurately than the Stacked LSTM. Moreover, the developed Bidirectional LSTM was compared with other state-of-the-art deep neural networks aimed at aircraft trajectory prediction. Promising results confirmed that Bidirectional LSTM exhibits the most stable MAPE across all prediction horizons.
      Citation: Aerospace
      PubDate: 2024-07-31
      DOI: 10.3390/aerospace11080625
      Issue No: Vol. 11, No. 8 (2024)
       
  • Aerospace, Vol. 11, Pages 626: Influence of Herringbone Grooves Inspired
           by Bird Feathers on Aerodynamics of Compressor Cascade under Different
           Reynolds Number Conditions

    • Authors: Shaobing Han, Zhijie Yang, Jingjun Zhong, Yuying Yan
      First page: 626
      Abstract: Nowadays, high aerodynamic load has made blade separation an issue for compact axial compressors under high-altitude low-Reynolds-number conditions. In this study, herringbone grooves inspired by bird feathers were applied to suppress the suction side separation and reduce loss. To study the effect of bio-inspired herringbone grooves on the aerodynamic performance of compressor cascades, a high subsonic compressor cascade was taken as the research object. Under the conditions of different Reynolds numbers, the effects of herringbone grooves of different depths on the flow separation were numerically studied. The research results show that at a high-Reynolds-number condition (Re = 5.6 × 105), the sawtooth-shaped wake induced by herringbone grooves increases the turbulent mixing loss near the suction surface, and the blade performance deteriorates. At a low-Reynolds-number condition (Re = 1.3 × 105), the span-wise secondary flow and micro-vortex structure induced by the herringbone grooves effectively suppress the laminar separation on the suction surface of the blade, and there is an optimal depth for the herringbone grooves that reduces the profile loss by 8.33% and increases the static pressure ratio by 0.55%. The selection principle of the optimal groove depth with the Re is discussed based on the research results under six low-Reynolds-number conditions.
      Citation: Aerospace
      PubDate: 2024-07-31
      DOI: 10.3390/aerospace11080626
      Issue No: Vol. 11, No. 8 (2024)
       
  • Aerospace, Vol. 11, Pages 627: High-Precision Composite Control of Driving
           Current for Non-Contact Annular Electromagnetic Stabilized Spacecraft
           Subject to Multiple Disturbances

    • Authors: He Liao, Haoxiang Yuan, Jinjin Xie
      First page: 627
      Abstract: Based on the design concept of dynamic and static isolation, disturbance-free payload (DFP) satellites can isolate the effects of interference on sensitive payloads, and can realize the high-precision control of the payload better than a traditional spacecraft. Among these, non-contact annular electromagnetic stabilized spacecraft (NCAESS) can effectively alleviate control output problems such as the six-degree-of-freedom coupling and nonlinear effects found in traditional non-contact spacecraft. As a key actuator, the driving current control of the non-contact annular electromagnetic actuator (NCAEA) will have a direct impact on the attitude performance of NCAESS. However, there are multiple interference effects present in the actual driving current control. Therefore, this paper proposes a composite control scheme to improve the driving accuracy by suppressing these multiple disturbances. Firstly, the variable-switching-frequency pulse-width modulation is used to adjust the switching frequency adaptively to reduce switch ripple. Secondly, feedforward compensation is employed to mitigate the back electromotive force. Thirdly, the robust Smith predictor is utilized to compensate for the digital control delay. Finally, an internal model proportional–integral controller with fuzzy rule is applied to adjust the parameters adaptively. The numerical simulation results demonstrate that the proposed approach can be adopted to enhance the robustness and dynamic response of the driving current effectively, which leads to precise control of the non-contact annular electromagnetic stabilized spacecraft.
      Citation: Aerospace
      PubDate: 2024-08-01
      DOI: 10.3390/aerospace11080627
      Issue No: Vol. 11, No. 8 (2024)
       
  • Aerospace, Vol. 11, Pages 628: Rotorcraft Airfoil Performance in Martian
           Environment

    • Authors: Enrico Giacomini, Lars-Göran Westerberg
      First page: 628
      Abstract: In 2021, the Ingenuity helicopter performed the inaugural flight on Mars, heralding a new epoch of exploration. However, the aerodynamics on Mars present unique challenges not found on Earth, such as low chord-based Reynolds number flows, which pose significant hurdles for future missions. The Ingenuity’s design incorporated a Reynolds number of approximately 20,000, dictated by the rotor’s dimensions. This paper investigates the implications of flows at a Reynolds number of 50,000, conducting a comparative analysis with those at 20,000 Re. The objective is to evaluate the feasibility of using larger rotor dimensions or extended airfoil chord lengths. An increase in the Reynolds number alters the size and position of Laminar Separation Bubbles (LSBs) on the airfoil, significantly impacting performance. This study leverages previous research on the structure and dynamics of LSBs to examine the flow around a cambered plate with 6% camber and 1% thickness in Martian conditions. This paper details the methods and mesh used for analysis, assesses airfoil performance, and provides a thorough explanation of the results obtained.
      Citation: Aerospace
      PubDate: 2024-08-01
      DOI: 10.3390/aerospace11080628
      Issue No: Vol. 11, No. 8 (2024)
       
  • Aerospace, Vol. 11, Pages 629: Simulation and Experimental Study of Gas
           Turbine Blade Tenon-Root Detachment on Spin Test

    • Authors: Maoyu Yu, Jianfang Wang, Haijun Xuan, Wangjiao Xiong, Zekan He, Mingmin Qu
      First page: 629
      Abstract: This paper addresses the critical issue of turbine blade containment in aircraft engines, crucial for ensuring flight safety. Through a comprehensive approach integrating numerical simulations and experimental validations, the containment capabilities of gas turbine engine casings are thoroughly analyzed. The study investigates the impact dynamics, deformation characteristics, and energy absorption mechanisms during blade detachment events, shedding light on the containment process. Based on the multi-stage nature of gas turbines, two different blade structures were designed for turbine blades. Utilizing finite element simulation and the Johnson–Cook constitutive equation, this study accurately simulated single-blade and dual-blade containment scenarios. The simulation results of the single blade indicate that the process of a gas turbine blade impacting the casing primarily consists of three stages. The second stage, where the tenon root strikes the casing, is identified as the main cause of casing damage. Meanwhile, in the dual-blade simulation, the second blade, influenced by the first blade, directly impacts the casing after fracturing, resulting in greater damage. Then, eight corresponding containment tests were conducted based on the simulation results, validating the accuracy of the simulation parameters. Experimental verification of simulation results further confirms the validity of the proposed containment curves, providing essential insights for optimizing casing design and enhancing the safety and reliability of aircraft engines.
      Citation: Aerospace
      PubDate: 2024-08-01
      DOI: 10.3390/aerospace11080629
      Issue No: Vol. 11, No. 8 (2024)
       
  • Aerospace, Vol. 11, Pages 630: Control-Oriented System Identification of
           Turbojet Dynamics

    • Authors: Francisco Villarreal-Valderrama, Eduardo Liceaga-Castro, Diana Hernandez-Alcantara, Carlos Santana-Delgado, Selcuk Ekici, Luis Amezquita-Brooks
      First page: 630
      Abstract: The autonomous operation of turbojets requires reliable, accurate, and manageable dynamical models for several key processes. This article describes a practical robust method for obtaining turbojet thrust and shaft speed models from experimental data. The proposed methodology combines several data mining tools with the intention of handling typical difficulties present during experimental turbojet modeling, such as high noise levels and uncertainty in the plant dynamics. The resulting shaft speed and thrust models achieved a percentage error of 0.8561% and 3.3081%, respectively, for the whole operating range. The predictive power of the resulting models is also assessed in the frequency domain. The turbojet cut frequencies are experimentally determined and were found to match those predicted by the identified models. Finally, the proposed strategy is systematically tested with respect to popular aeroengine models, outperforming them both in the time and frequency domains. These results allow us to conclude that the proposed modeling method improves current modeling approaches in both manageability and predictive power.
      Citation: Aerospace
      PubDate: 2024-08-01
      DOI: 10.3390/aerospace11080630
      Issue No: Vol. 11, No. 8 (2024)
       
  • Aerospace, Vol. 11, Pages 631: Dynamic Fault Tree Model of Civil Aircraft
           Avionics Network Transmission Failure Based on Optimized Extended Fuzzy
           Algorithm

    • Authors: Zhaojun Gu, Yinuo Zhang, He Sui
      First page: 631
      Abstract: The avionics network supports high-safety-level flight operations, with the analysis of transmission failures serving as a crucial means for its safety evaluation. Due to the time-dependent nature of the failure probability in avionics networks, traditional constant and unchangeable probability values can deviate from the actual situation under specific conditions. This deviation may lead to inadequate responses to occasional events and potentially cause flight accidents. A Dynamic Fault Tree (DFT) model for civil aircraft avionics network transmission failures, based on an optimized extended fuzzy algorithm, is introduced in this paper. Initially focusing on event correlations, a DFT is established for the transmission failure of the Avionics Full Duplex Switched Ethernet (AFDX). Subsequently, considering the variations between events, triangular fuzzy processing is applied to the event failure rates based on relative confidence levels. Finally, by optimizing the weakest t-norm operator, the failure probability intervals are aggregated and the fuzzy scale is regulated. Experimental results demonstrate that, compared to the static-minimum t-norm and traditional weakest t-norm methods, the proposed approach enhances the accuracy of the fuzzy failure probability intervals by 66.15% and 40.59%, respectively. Concurrently, it maintains consistency in the ranking of event importance, highlighting the superior effectiveness of the proposed method in analyzing transmission failures in avionics networks.
      Citation: Aerospace
      PubDate: 2024-08-01
      DOI: 10.3390/aerospace11080631
      Issue No: Vol. 11, No. 8 (2024)
       
  • Aerospace, Vol. 11, Pages 632: Investigations on Trimming Strategy and
           

    • Authors: Guoqing Zhao, Zhuangzhuang Cui, Qijun Zhao, Xi Chen, Peng Li
      First page: 632
      Abstract: Numerical simulations were conducted to analyze the unsteady aerodynamic characteristics of a tiltrotor aircraft with different conversion strategies. Firstly, the CFD method was established by taking the interaction between the rotor and wing into account, as well as the body-fitted grid of the tiltrotor. Then, the trimming approach of the rotor and wing was developed to ensure longitudinal balance of the aircraft, and the method for determining the conversion corridor of the tiltrotor aircraft was proposed by considering the limitations imposed by wing stall and the required power of the rotor. Finally, the aerodynamic characteristics of the rotor and wing during the continuous conversion process were investigated, considering various tilting angular velocities and horizontal accelerations of the tiltrotor. The numerical results indicated that a smaller acceleration can enhance the efficiency of the tiltrotor. However, this would increase the complexity of trimming the fuselage attitude angle. It was also found that excessive acceleration could exceed the required power limit of the tiltrotor, rendering the conversion strategy infeasible.
      Citation: Aerospace
      PubDate: 2024-08-01
      DOI: 10.3390/aerospace11080632
      Issue No: Vol. 11, No. 8 (2024)
       
  • Aerospace, Vol. 11, Pages 633: Integrated Design and Simulation of
           Helicopter Nuclear, Biological, and Chemical Protection System

    • Authors: Yilong Wen, Xiaodong Mao, Hexiang Wang, Liping Pang, Quanyu Zhao
      First page: 633
      Abstract: The helicopter’s aircrew faces significant challenges in nuclear, biological, and chemical (NBC) environments due to limited protection devices and crowded space. To safeguard the security and ensure the comfort of the aircrew, the development of a helicopter NBC protection system is crucial. In this study, a helicopter NBC protection system was designed using a top-level architecture with an advanced system-integrated approach. Detailed configuration designs were developed for each subsystem, including air source pressurization, renewable NBC filtration ventilation, cabin temperature, and pressure control system. To verify the reliability of the adsorbent model, a Langmuir isotherm equation was adapted and validated using the experiment data. To verify the performance of the designed system, a dynamic simulation model was created using AMESIM. The findings demonstrate that the cabin temperature and pressure control system can greatly satisfy the demand for aircrews under various working conditions. Furthermore, the renewable NBC filtration ventilation system effectively adsorbs NBC substances and achieves onboard regeneration, thereby extending the working lifespan in contaminated environments. This study contributes to providing an innovative idea for helicopter NBC protection systems.
      Citation: Aerospace
      PubDate: 2024-08-01
      DOI: 10.3390/aerospace11080633
      Issue No: Vol. 11, No. 8 (2024)
       
  • Aerospace, Vol. 11, Pages 634: The Bond Graph Modeling and Experimental
           Verification of a Hydraulic Inertial Vibration Isolator Including
           Nonlinear Effects

    • Authors: Niuniu Liu, Cheng Li, Liwei Zhang, Zhiyang Lei, Jing Yang, Fuqiang Lai
      First page: 634
      Abstract: Passive vibration isolation techniques with low-frequency characteristics have been a hot topic in the aerospace field. A hydraulic inertial vibration isolator is a highly effective type of isolator for controlling low-frequency vibrations. It typically consists of a main spring, a minor spring, an inertial mass, and a fluid domain. Due to its multi-domain nature, analyzing the isolation mechanism of this type of isolator is challenging. The bond graph method is employed to establish the dynamic model of the isolator. Subsequently, the state equations of the isolator are derived, and the energy equations of both the mechanical and the fluid parts of the isolator are obtained. Based on this, the energy transfer characteristics between the mechanical and fluid domains inside the isolator under external excitation are discussed. The time-domain response of the forces transmitted to the foundation is analyzed. It is shown that the anti-resonance frequency occurs when the forces transmitted to the foundation generated by the main spring and the fluid pressure are equal to that of the minor spring. To verify the proposed method’s correctness, a prototype of the isolator is designed and a carefully designed experiment is conducted. The acceleration transmissibility of the isolator is used to conduct a comparative study. The results show that the theoretical results are in good agreement with the experimental results. To depict the dynamic characteristics of the isolator under large amplitude vibration, the nonlinear dynamic model of the isolator is developed, and the corresponding force transmissibility of the isolator is formulated. The energy flow between the mechanical and the fluid domains under this condition is also analyzed. The results indicate that the energy flow responses exhibit a similar change tendency to the force transmissibility. However, the peak of the energy ratio between the mechanical subsystem and the fluid is the same as the linear condition, suggesting that this value is determined by the amplification ratio of the isolator. This research provides enhanced physical insight to understand the dynamic characteristics of this type of isolator and will help to shorten the design cycle of the isolator.
      Citation: Aerospace
      PubDate: 2024-08-02
      DOI: 10.3390/aerospace11080634
      Issue No: Vol. 11, No. 8 (2024)
       
  • Aerospace, Vol. 11, Pages 635: Fuelless On-Orbit Assembly of a Large Space
           Truss Structure Using Repulsion of the Service Spacecraft by Robotic
           Manipulators

    • Authors: Vladislav Orlov, Uliana Monakhova, Mikhail Ovchinnikov, Danil Ivanov
      First page: 635
      Abstract: A servicing spacecraft motion control approach for the problem of on-orbit truss structure assembly is developed in this paper. It is considered that a cargo container with a rod set and servicing spacecraft are in orbit initially. The assembly procedure is based on spacecraft free-flight motion between the structure’s specified points. The spacecraft is equipped with two robotic manipulators capable of attaching to the structure and holding rods. In addition, the spacecraft can repulse from the structure with a given relative velocity using a manipulator, so the spacecraft and the structure receive impulses. The repulsion velocity vector is calculated in order to reach the structure target point to deliver and install the rod into the truss structure, or to reach the cargo container and take a rod. The problem of searching the repulsion velocity is formulated as an optimization problem with constraints, taking into account the limited value of the repulsion velocity, collision avoidance with structure, restrictions on the angular velocity and translational motion of the structure in the orbital reference frame. This problem is solved numerically with an initial guess vector obtained analytically for simplified motion cases. The application of the proposed control scheme to the assembly of a truss-based antenna is demonstrated. It is shown that the servicing spacecraft is successfully transferred between the structure points by means of manipulator repulsion. Main features and limitations of the assembly problem using a spacecraft with two manipulators are discussed.
      Citation: Aerospace
      PubDate: 2024-08-02
      DOI: 10.3390/aerospace11080635
      Issue No: Vol. 11, No. 8 (2024)
       
  • Aerospace, Vol. 11, Pages 636: Flutter Optimization of Carbon/Epoxy Plates
           Based on a Fast Tree Algorithm

    • Authors: Mirko Dinulović, Aleksandar Bengin, Branimir Krstić, Marjan Dodić, Miloš Vorkapić
      First page: 636
      Abstract: This study focuses on optimizing carbon/epoxy laminate configurations to maximize the flutter speed of composite structures using a Fast Tree Regression algorithm. Initially, a seed dataset was created, using finite element method (FEM) modal analysis for common stack-ups used in composite fins and UAV components. The FEM analysis, based on the Lanczos algorithm for extracting modal frequencies in bending and torsion, was verified through experimental modal analysis using an AS-4/3501-6 composite system. Custom software was developed to interface with the FEA modal software, enabling the generation and augmentation of laminate dataset scenarios. The seed dataset was expanded until the coefficient of determination (R2) reached at least 0.95. Various regression algorithms, including Fast Forest Regression, Fast Tree Regression, Sdca Regression, and Lbfgs Poisson Regression, were evaluated. The Fast Tree Regression algorithm was selected for further analysis due to its superior performance. This algorithm was applied to a design space of nearly 2000 potential laminate candidates, focusing on symmetric lay-ups to avoid undesirable coupling between bending and torsion in UAV and missile control surfaces. The final optimized lay-ups, exhibit the highest Delta function values (the squared difference of modal frequencies in torsion and bending), indicating the expected highest flutter speeds. The results demonstrate the efficacy of tailored composite materials in achieving specific aerodynamic performance goals.
      Citation: Aerospace
      PubDate: 2024-08-03
      DOI: 10.3390/aerospace11080636
      Issue No: Vol. 11, No. 8 (2024)
       
  • Aerospace, Vol. 11, Pages 637: Dispersion Analysis of Plane Wave
           Propagation in Lattice-Based Mechanical Metamaterial for Vibration
           Suppression

    • Authors: Natsuki Tsushima, Yuta Hayashi, Tomohiro Yokozeki
      First page: 637
      Abstract: Phononic crystals based on lattice structures provide important wave dispersion characteristics as band structures, showing excellent compatibility with additive manufacturing. Although the lattice structures have shown the potential for vibration suppression, a design guideline to control the frequency range of the bandgap has not been well established. This paper studies the dispersion characteristics of plane wave propagation in lattice-based mechanical metamaterials to realize effective vibration suppression for potential aerospace applications. Triangular and hexagonal periodic lattice structures are mainly studied in this paper. The influence of different geometric parameters on the bandgap characteristics is investigated. A finite element approach with Floquet–Bloch’s principles is implemented to effectively evaluate the dispersion characteristics of waves in lattice structures, which is validated numerically and experimentally with a 3D-printed lattice plate. Based on numerical studies with the developed analysis framework, the influences of the geometric parameters of lattice plate structures on dispersion characteristics can mainly be categorized into three patterns: change in specific branches related to in-plane or out-of-plane vibrations, upward/downward shift in frequency range, and drastic change in dispersion characteristics. The results obtained from the study provide insight into the design of band structures to realize vibration suppression at specific frequencies for engineering applications.
      Citation: Aerospace
      PubDate: 2024-08-04
      DOI: 10.3390/aerospace11080637
      Issue No: Vol. 11, No. 8 (2024)
       
  • Aerospace, Vol. 11, Pages 638: A Survey of Aero-Engine Blade Modeling and
           Dynamic Characteristics Analyses

    • Authors: Yaqiong Zhang, Fubin Wang, Jinchao Liu, Heng Zhao, Chao Fu, Weihao Zhai, Kuan Lu
      First page: 638
      Abstract: The rotating blade is a key component of an aero-engine, and its vibration characteristics have an important impact on the performance of the engine and are vital for condition monitoring. This paper reviews the research progress of blade dynamics, including three main aspects: modeling of blades, solution methods, and vibration characteristics. Firstly, three popular structural dynamics models for blades are reviewed, namely lumped-mass model, finite element model, and semi-analytical model. Then, the solution methods for the blade dynamics are comprehensively described. The advantages and limitations of these methods are summarized. In the third part, this review summarizes the properties of the modal and vibration responses of aero-engine blades and discusses the typical forms and mechanisms of blade vibration. Finally, the deficiencies and limitations in the current research on blade modeling and vibration analysis are summarized, and the directions for future efforts are pointed out. The purpose of this review is to provide meaningful insights to researchers and engineers in the field of aero-engine blade modeling and dynamic characteristics analysis.
      Citation: Aerospace
      PubDate: 2024-08-05
      DOI: 10.3390/aerospace11080638
      Issue No: Vol. 11, No. 8 (2024)
       
  • Aerospace, Vol. 11, Pages 639: Effects of Wire-Wrapping Patterns and Low
           Temperature on Combustion of Propellant Embedded with Metal Wire

    • Authors: Qiu Wu, Jiangong Zhao, Quanbin Ren
      First page: 639
      Abstract: Incorporating silver wires into propellant has emerged as a highly effective strategy for enhancing propellant burning rates, a technique extensively deployed in the construction of numerous fielded sounding rockets and tactical missiles. Our research, employing a multi-faceted approach encompassing thermogravimetric-differential scanning calorimetry measurements (TG-DSC), combustion diagnoses, burning rate tests, and meticulous collection of condensed combustion products, sought to elucidate how variations in silver wire quantity and winding configuration impact the combustion properties of propellants. Our findings underscore the remarkable efficacy of double tightly twisted silver wire in significantly boosting propellant burning rates under ambient conditions. Moreover, at lower temperatures, the reduced gap between the propellant and silver wire further magnifies the influence of silver wire on burning rates. However, it is noteworthy that the relationship between burning speed and combustion efficiency is not deterministic. While a smaller cone angle of the burning surface contributes to heightened burning rates, it concurrently exacerbates the polymerization effect of vapor phase aluminum particles, consequently diminishing propellant combustion efficiency. Conversely, propellants configured with sparsely twinned silver wires exhibit notable enhancements in combustion efficiency, despite a less pronounced impact on the burning rate attributed to the larger cone angle of the burning surface. Remarkably, these trends persist at lower temperatures. Based on the principle of heat transfer balance, a theoretical model for the combustion of propellants with wire inserts is developed. The reliability of this theoretical model is validated through a comparison of calculated values with experimental data. Our research outcomes carry significant implications for guiding the application and advancement of the silver wire method in solid propellants for solid rocket motors, offering valuable insights to inform future research and development endeavors in this domain.
      Citation: Aerospace
      PubDate: 2024-08-06
      DOI: 10.3390/aerospace11080639
      Issue No: Vol. 11, No. 8 (2024)
       
  • Aerospace, Vol. 11, Pages 640: Approximation of Closed-Loop Sensitivities
           in Robust Trajectory Optimization under Parametric Uncertainty

    • Authors: Tuğba Akman, Joseph Z. Ben-Asher, Florian Holzapfel
      First page: 640
      Abstract: Trajectory optimization is an essential tool for the high-fidelity planning of missions in aerospace engineering in order to increase their safety. Robust optimal control methods are utilized in the present study to address environmental or system uncertainties. To improve robustness, holistic approaches for robust trajectory optimization using sensitivity minimization with system feedback and predicted feedback are presented. Thereby, controller gains to handle uncertainty influences are optimized. The proposed method is demonstrated in an application for UAV trajectories. The resulting trajectories are less prone to unknown factors, which increases mission safety.
      Citation: Aerospace
      PubDate: 2024-08-06
      DOI: 10.3390/aerospace11080640
      Issue No: Vol. 11, No. 8 (2024)
       
  • Aerospace, Vol. 11, Pages 641: Test Scheme Design and Numerical Simulation
           of Composite Thrust Reverser Cascade

    • Authors: Dingzhou Wu, Xiuhua Chen, Hongyan Qiu
      First page: 641
      Abstract: The thrust reverser system stands as the critical component in contemporary large civil aviation, significantly impacting operational efficiency. Owing to their significant weight-reduction benefits, composite materials have emerged as a prominent trend in structural design in recent years. The aim of this research is to optimize the design of the thrust reverser cascade by replacing metal materials with composite materials and to propose a method for conducting mechanical tests on the cascade without a wind tunnel using a new loading scheme and a device that is simpler, more convenient, and less expensive. Focusing on a composite thrust reverser cascade with an inclined blade and beam, the structural and operational load characteristics of the cascade were analyzed and a finite element model incorporating progressive damage analysis was established. The progressive damage analyses of both the global and sub-model elucidated that initial structural degradation manifests near the mounting holes, with the matrix compression failure mode. In addition, a static test method was devised employing levers and hooks. Comparative analyses between test and numerical results demonstrate congruence. The research in this paper provides guidance for the design and testing of the composite thrust reverser cascade.
      Citation: Aerospace
      PubDate: 2024-08-07
      DOI: 10.3390/aerospace11080641
      Issue No: Vol. 11, No. 8 (2024)
       
  • Aerospace, Vol. 11, Pages 642: Investigation of the Film Cooling
           Performance of Laminated SiCfSiC Composite Plates

    • Authors: Zhaoguo Mi, Zhenhua Chen, Kanghe Jiang, Weihua Yang
      First page: 642
      Abstract: Silicon carbide fiber-reinforced silicon carbide matrix ceramic composites (SiCf/SiC) are extensively utilized in high-temperature resistant materials in the aerospace industry. This study investigated the influence of stacking structure on the performance of SiCf/SiC laminated composite plates with film cooling. Initially, the thermal conductivity of cross-piled SiCf/SiC composites was determined using the laser flash analysis (LFA) method and differential scanning calorimetry (DSC) method. Subsequently, a representative volume element (RVE) model that reflected the stacking structure was established. The anisotropic thermal conductivity of the unidirectional SiCf/SiC layer was calculated using numerical methods and experimental results. Finally, numerical simulations were carried out to assess the film cooling effectiveness of various stacking sequences and layers. The results showed that the thermal conductivity values predicted by the RVE model for the laminated composite aligned well with the experimental results, and the unidirectional SiCf/SiC composite thermal conductivities at different temperatures were obtained. The stacking sequence impacted the temperature distribution near the film hole, with the [0-90-0] structure exhibiting a more pronounced effect on film cooling performance compared with the [0-90] and [0-90-90-0] structures. The performance of the film cooling in the laminated SiCf/SiC composites was consistent across all stacking layers [0-90]1, [0-90]2, and [0-90]3. The maximum difference in overall cooling efficiency was 1.7% between [0-90-0]1 and [0-90]1 and [0-90-90-0]1
      Citation: Aerospace
      PubDate: 2024-08-07
      DOI: 10.3390/aerospace11080642
      Issue No: Vol. 11, No. 8 (2024)
       
  • Aerospace, Vol. 11, Pages 565: Development of Scenarios as Problem-Space
           Descriptions in Aerospace Conceptual Design

    • Authors: Karl Kindström Andersson, Kent E. Andersson
      First page: 565
      Abstract: In the defense and security domain, scenarios are often descriptions of stakeholder needs, future events, and the environment. They are used for the elicitation of requirements in development of capabilities, organizations, and technical systems. In the conceptual design of aerospace applications, models of scenarios can also represent and communicate a problem-space, enabling trade-space exploration and system effectiveness robustness analysis, which provide valuable input to decision-makers. This study utilizes design science to develop a scenario framework for solution-agnostic representations of a problem-space for use in aerospace conceptual design- and trade-space exploration. A scenario ontology is developed, describing the constituent concepts of scenarios and their relationships, followed by a method for creating scenarios and evaluating their validity. Within the EU project COLOSSUS, it is demonstrated that the scenario framework has utility both for market-pull and technology-push conceptual design. Establishing an ontology for scenarios and a method for creating them as well as evaluating their validity is another step in improving the aerospace conceptual design phase.
      Citation: Aerospace
      PubDate: 2024-07-10
      DOI: 10.3390/aerospace11070565
      Issue No: Vol. 11, No. 7 (2024)
       
  • Aerospace, Vol. 11, Pages 566: Design of Entire-Flight Pinpoint Return
           Trajectory for Lunar DRO via Deep Neural Network

    • Authors: Xuxing Huang, Baihui Ding, Bin Yang, Renyuan Xie, Zhengyong Guo, Jin Sha, Shuang Li
      First page: 566
      Abstract: Lunar DRO pinpoint return is the final stage of manned deep space exploration via a lunar DRO station. A re-entry capsule suffers from complicated dynamic and thermal effects during an entire flight. The optimization of the lunar DRO return trajectory exhibits strong non-linearity. To obtain a global optimal return trajectory, an entire-flight lunar DRO pinpoint return model including a Moon–Earth transfer stage and an Earth atmosphere re-entry stage is constructed. A re-entry point on the atmosphere boundary is introduced to connect these two stages. Then, an entire-flight global optimization framework for lunar DRO pinpoint return is developed. The design of the entire-flight return trajectory is simplified as the optimization of the re-entry point. Moreover, to further improve the design efficiency, a rapid landing point prediction method for the Earth re-entry is developed based on a deep neural network. This predicting network maps the re-entry point in the atmosphere and the landing point on Earth with respect to optimal control re-entry trajectories. Numerical simulations validate the optimization accuracy and efficiency of the proposed methods. The entire-flight return trajectory achieves a high accuracy of the landing point and low fuel consumption.
      Citation: Aerospace
      PubDate: 2024-07-10
      DOI: 10.3390/aerospace11070566
      Issue No: Vol. 11, No. 7 (2024)
       
  • Aerospace, Vol. 11, Pages 567: Compound Control Design of Near-Space
           Hypersonic Vehicle Based on a Time-Varying Linear Quadratic Regulator and
           Sliding Mode Method

    • Authors: Huan Wang, Di Zhou, Yiqun Zhang, Chaofei Lou
      First page: 567
      Abstract: The design of a hypersonic vehicle controller has been an active research field in the last decade, especially when the vehicle is studied as a time-varying system. A time-varying compound control method is proposed for a hypersonic vehicle controlled by the direct lateral force and the aerodynamic force. The compound control method consists of a time-varying linear quadratic regulator (LQR) control law for the aerodynamic rudder and a sliding mode control law for the lateral thrusters. When the air rudder cannot continuously produce control force and torque, the direct lateral force is added to the system. To solve the problem that LQR cannot directly obtain the analytical solution of the time-varying system, a novel approach to approximate analytical solutions using Jacobi polynomials is proposed in this paper. Finally, the stability of the time-varying compound control system is proven by the Lyapunov–Krasovskii functional (LKF). The simulation results show that the proposed compound control method is effective and can improve the fast response ability of the system.
      Citation: Aerospace
      PubDate: 2024-07-10
      DOI: 10.3390/aerospace11070567
      Issue No: Vol. 11, No. 7 (2024)
       
  • Aerospace, Vol. 11, Pages 568: Implementing a Multi-Attribute
           Decision-Making-Based Approach to Evaluate Small Electric Vertical Takeoff
           and Landing Fixed-Wing Drones with Mission Efficiency

    • Authors: Zhuo Bai, Bangchu Zhang, Zhong Tian, Shangnan Zou, Weiyu Zhu
      First page: 568
      Abstract: Evaluating the mission efficiency of various drone configurations under complex, multi-source, and multi-dimensional requirements remains a significant challenge. This study aimed to develop a comprehensive decision support system (DSS) that employs mission efficiency evaluation, probabilistic hesitant fuzzy sets (PHFs), and multi-attribute decision-making (MADM) methods to assess and optimize drone design. In the proposed method, mission efficiency is defined as a composite measure of the flight performance, adaptability, and economic viability required to complete a mission. By designing a “demand–capability–design” mapping approach, this system effectively resolves multi-attribute conflicts in the decision-making process. To demonstrate the proposed approach, a set of small electric vertical takeoff and landing fixed-wing (e-VTOLFW) drones are compared and ranked based on their mission efficiency. The impacts of different mission requirements on drone evaluation are also discussed. The results demonstrate that this model resolves the traditional issue of unclear information flow in drone design. By improving the evaluation criteria, it enhances informed decision making and the robustness of evaluation results in drone design assessments. Additionally, the model is generalizable and can be widely applied to similar fields such as “demand–product design”, improving the understanding and optimization of product performance.
      Citation: Aerospace
      PubDate: 2024-07-11
      DOI: 10.3390/aerospace11070568
      Issue No: Vol. 11, No. 7 (2024)
       
  • Aerospace, Vol. 11, Pages 569: Incidence Adaptation to the Influence of
           Wake Sweeps on the Aerodynamic Performance of a Low-Pressure Turbine
           Cascade

    • Authors: Xuejian Li, Xinglong Fang, Le Cai, Lan Wang, Xinlei Hu, Yingjie Chen, Songtao Wang
      First page: 569
      Abstract: In order to investigate the transport law of an unsteady wake in a downstream cascade channel in a turbine stage environment, this study was based on a self-designed unsteady wake generator, and a low-pressure turbine cascade was the research object. The research was carried out through a combination of experiments and numerical simulation. The results show that in the range of −50° to 20° inflow incidence, there is no separation on the blade suction surface, the total pressure loss coefficient is low, and the cascade has good adaptability to the inflow incidence. When the incoming flow is at a negative incidence, the transport of the unsteady upstream wake to the downstream unsteady wake is basically the same; the same holds for a non-negative incidence. When the upstream unsteady wake is transported downstream in the cascade channel, the wake near the cascade suction surface follows a detour and barely interacts with the mainstream fluid. The total pressure loss fluctuation value obtained via numerical calculation shows good periodicity; therefore, the unsteady cascade effect under the action of upstream wake sweeping becomes very obvious.
      Citation: Aerospace
      PubDate: 2024-07-11
      DOI: 10.3390/aerospace11070569
      Issue No: Vol. 11, No. 7 (2024)
       
  • Aerospace, Vol. 11, Pages 570: Analysis of Development Trends for Rotating
           Detonation Engines Based on Experimental Studies

    • Authors: Min-Sik Yun, Tae-Seong Roh, Hyoung Jin Lee
      First page: 570
      Abstract: Rotating detonation engines (RDEs), which are Humphrey cycle-based constant-volume combustion engines, utilize detonation waves to attain higher efficiencies compared with conventional constant-pressure combustion engines through pressure gain. Such engines have garnered significant interest as future propulsion technologies, and thus, numerous research and development initiatives have been launched specific to RDEs in various forms. This paper presents a survey of research and development trends in RDE operating systems, based on experimental studies conducted worldwide since the 2010s. Additionally, a performance comparison of RDEs developed to date is presented.
      Citation: Aerospace
      PubDate: 2024-07-11
      DOI: 10.3390/aerospace11070570
      Issue No: Vol. 11, No. 7 (2024)
       
  • Aerospace, Vol. 11, Pages 571: Role of Partial Flexibility on Flow
           Evolution and Aerodynamic Power Efficiency over a Turbine Blade Airfoil

    • Authors: Kemal Koca, Mustafa Serdar Genç
      First page: 571
      Abstract: In this study, the aerodynamic performance of a cambered wind turbine airfoil with a partially flexible membrane material on its suction surface was examined experimentally across various angles of attack and Reynolds numbers. It encompassed physical explanation at the pre/post-stall regions. The results of particle image velocimetry revealed that the laminar separation bubble was diminished or even suppressed when a local flexible membrane material was employed on the suction surface of the wind turbine blade close to the leading edge. The results of the deformation measurement indicated that the membrane had a range of flow modes. This showed that the distribution of aerodynamic fluctuations due to the presence of LSB-induced vortices was reduced. This also led to a narrower wake region occurring. Aerodynamic performance improved and aerodynamic vibration significantly lowered, particularly at the post-stall zone, according to the results of the aerodynamic force measurement. In addition to the lift force, the drag force was enormously reduced, corroborating and matching well with the results of PIV and deformation measurements. Consequently, significant benefits for a turbine blade were notably observed, including aerodynamic performance enhancement, increased aerodynamic power efficiency, and reduced aerodynamic vibration.
      Citation: Aerospace
      PubDate: 2024-07-11
      DOI: 10.3390/aerospace11070571
      Issue No: Vol. 11, No. 7 (2024)
       
  • Aerospace, Vol. 11, Pages 572: Semianalytical Research on
           Aerothermoelastic Behaviors of Functionally Graded Plates under Arbitrary
           Temperature Fields in Hypersonic Vehicles

    • Authors: Chang Li, Zhiqiang Wan, Xiaozhe Wang, Chao Yang, Keyu Li
      First page: 572
      Abstract: Hypersonic vehicles are susceptible to considerable aerodynamic heating and noticeable aerothermoelastic effects during flight due to their high speeds. Functionally graded materials (FGMs), which enable continuous changes in material properties by varying the ratio of different materials, provide both thermal protection and load-bearing capabilities. Therefore, they are widely used in thermal protection structures for hypersonic vehicles. In this work, the aerothermoelastic behaviors of functionally graded (FG) plates under arbitrary temperature fields are analyzed via a semianalytical method. This research develops a method considering the influence of thermal loading, specifically the decrease in stiffness due to thermal stresses, as well as the correlation between material properties and temperatures under arbitrary temperature fields, based on Ritz’s method. The classical plate theory, von–Karman’s large defection plate theory and piston theory are employed to formulate the strain energy, kinetic energy and external work functions of the system. This paper presents a novel analysis of static aerothermoelasticity of FG plates, in addition to the linear/nonlinear flutter under arbitrary temperature fields, such as uniform, linear and nonlinear temperature fields. In addition, the effects of the volume fraction index, dynamic pressure, and temperature increase on the aerothermoelastic characteristics of FG plates are analyzed.
      Citation: Aerospace
      PubDate: 2024-07-12
      DOI: 10.3390/aerospace11070572
      Issue No: Vol. 11, No. 7 (2024)
       
  • Aerospace, Vol. 11, Pages 573: Experimental Study on the Influence of
           Microwave Energy Pulse Width and Duty Cycle on Evaporation and Ignition
           Characteristics of ADN-Based Liquid Propellant Droplets

    • Authors: Dezhao Yu, Jiale Yao, Jiafu Ma, Yangyang Hou, Shaoyun Zhang, Yusong Yu
      First page: 573
      Abstract: This study investigates the evaporation and ignition characteristics of a single droplet of ammonium dinitramide (ADN)-based liquid propellant utilizing a waveguide resonant cavity device, in conjunction with a high-speed photographic imaging system and testing system. Experimental methods are employed to analyze the impact of microwave pulse width and duty cycle on the puffing and meicro-explosion phenomena of the droplet, as well as the delay time and duration of ignition. The experimental findings reveal that increasing the duty cycle enhances the ignition success rate and diminishes flame development time. Specifically, elevating the microwave duty cycle from 60% to 80% reduces the ignition delay time of the droplet from 132.8 ms to 88.1 ms, and the ignition duration from 23.1 ms to 19.9 ms. Furthermore, an increase in microwave energy pulse width expedites the combustion process of the flame and influences plasma generation. Increasing the pulse width of microwave energy from 20 µs to 40 µs prolongs the ignition delay time from 140.3 ms to 200.5 ms and extends the ignition duration from 56.7 ms to 77.8 ms. Additionally, it is observed that a higher duty cycle leads to a more pronounced puffing phenomenon that initiates earlier. In contrast, a higher pulse width results in a more pronounced puffing phenomenon that commences later. This study provides a thorough investigation into the microwave ignition mechanism of ADN-based liquid propellants, offering theoretical insights into the ignition and combustion stability of such propellants in microwave-assisted ignition systems.
      Citation: Aerospace
      PubDate: 2024-07-12
      DOI: 10.3390/aerospace11070573
      Issue No: Vol. 11, No. 7 (2024)
       
  • Aerospace, Vol. 11, Pages 574: A Novel Approach Using Non-Experts and
           Transformation Models to Predict the Performance of Experts in A/B Tests

    • Authors: Phillip Stranger, Peter Judmaier, Gernot Rottermanner, Carl-Herbert Rokitansky, Istvan-Szilard Szilagyi, Volker Settgast, Torsten Ullrich
      First page: 574
      Abstract: The European Union is committed to modernising and improving air traffic management systems to promote environmentally friendly air transport. However, the safety-critical nature of ATM systems requires rigorous user testing, which is hampered by the scarcity and high cost of air traffic controllers. In this article, we address this problem with a novel approach that involves non-experts in the evaluation of expert software in an A/B test setup. Using a transformation model that incorporates auxiliary information from a newly developed psychological questionnaire, we predict the performance of air traffic controllers with high accuracy based on the performance of students. The transformation model uses multiple linear regression and auxiliary information corrections. This study demonstrates the feasibility of using non-experts to test expert software, overcoming testing challenges and supporting user-centred design principles.
      Citation: Aerospace
      PubDate: 2024-07-12
      DOI: 10.3390/aerospace11070574
      Issue No: Vol. 11, No. 7 (2024)
       
  • Aerospace, Vol. 11, Pages 575: Biofuel–Electric Hybrid Aircraft
           Application—A Way to Reduce Carbon Emissions in Aviation

    • Authors: Shengfei Dong, Zehua Song, Zheyi Meng, Ziyu Liu
      First page: 575
      Abstract: As global warming intensifies, the world is increasingly concerned about carbon emissions. As an important industry that affects carbon emissions, the air transportation industry takes on the important task of energy saving and emission reduction. For this reason, major airlines have designed or will design different kinds of new-energy aircraft; however, each aircraft has a different scope of application according to its energy source. Biofuels have an obvious carbon emission reduction effect in the whole life cycle, which can offset the drawback of the high pollutant emission of traditional fossil fuels in the preparation and combustion stages. At the same time, a battery has zero emissions in the operating condition, while the low energy density also makes it more applicable to short-range navigation in small aircraft. In this paper, the development direction of a biofuel–electric hybrid aircraft is proposed based on the current development of green aviation, combining the characteristics of biofuel and electric aircraft.
      Citation: Aerospace
      PubDate: 2024-07-13
      DOI: 10.3390/aerospace11070575
      Issue No: Vol. 11, No. 7 (2024)
       
  • Aerospace, Vol. 11, Pages 576: Design and Implementation of a Land-Air
           Omnidirectional Mobile Robot

    • Authors: Changlong Ye, Hongyu Wang, Suyang Yu, Xinyu Ma, Ruizhe Zhou
      First page: 576
      Abstract: This paper proposes a new type of omnidirectional mobile robot for land and air, which has three motion modes, combines the motion characteristics of land motion and air flight, has the ability to climb walls, and can be actively deformed to adapt to the working conditions according to the current working environment. The robot incorporates an innovative “rotor blade–single row omnidirectional wheel” composite structure, which is mainly characterized by a single row of continuous switching wheels covering the outside of each rotor blade, and does not need to provide additional power when moving on the ground and walls, relying on the driving force generated by the rotor blades to drive the continuous switching wheels driven by the rotor blades. This structure can effectively combine the land movement mode, wall crawling mode, and air flight mode, which reduces the energy consumption of the robot without increasing the weight, and we design a deformation device that can realize the transformation of the three modes into each other. This paper mainly focuses on the design of the robot structure and the analysis of the movement method, and the land omnidirectional movement experiments, wall crawling experiments, and air flight experiments were, respectively, carried out, and the results show that the proposed land and air omnidirectional mobile robot has the ability to adapt to the movement of each scene, and improves the upper limit of the robot’s operation.
      Citation: Aerospace
      PubDate: 2024-07-14
      DOI: 10.3390/aerospace11070576
      Issue No: Vol. 11, No. 7 (2024)
       
  • Aerospace, Vol. 11, Pages 577: Design of Low-Cost Simulation Space Micro
           Debris Launch Device

    • Authors: Renjie Yang, Kai Tang, Xuqiang Lang, Cheng He, Yu Liu, Yue Liu
      First page: 577
      Abstract: The high cost and low emission frequency of microparticle launchers have resulted in a long lead time for the development of detectors for micro-debris in space. In this paper, two low-cost, high-emission-frequency, small-size, millimeter-sized particle launchers are designed using the principles of gas expansion and surge propulsion by a high-speed air stream. Electrostatic detection is utilized to determine the emission velocity of the microbeads and their deviation from a specific position on the flight trajectory. The emission rate and accuracy of both methods were experimentally evaluated, along with the deviation of the detection system. Both devices emitted microbeads to simulate micro-debris, providing experimental data for the development of a space debris detector and establishing research conditions for studying the impact of micro-debris.
      Citation: Aerospace
      PubDate: 2024-07-15
      DOI: 10.3390/aerospace11070577
      Issue No: Vol. 11, No. 7 (2024)
       
  • Aerospace, Vol. 11, Pages 578: Ground-Based Characterisation of a Compact
           Instrument for Gamma-ray Burst Detection on a CubeSat Platform

    • Authors: Rachel Dunwoody, David Murphy, Alexey Uliyanov, Joseph Mangan, Maeve Doyle, Joseph Thompson, Cuan de Barra, Lorraine Hanlon, David McKeown, Brian Shortt, Sheila McBreen
      First page: 578
      Abstract: Gamma-ray bursts (GRBs) are intense and short-lived cosmic explosions. Miniaturised CubeSat-compatible instruments for the study of GRBs are being developed to help bridge the gap in large missions and assist in achieving full sky coverage. CubeSats are small, compact satellites conforming to a design standard and have transformed the space industry. They are relatively low-cost and are developed on fast timescales, which has provided unparalleled access to space. This paper focuses on GMOD, the gamma-ray module, onboard the 2U CubeSat EIRSAT-1, launched on December 1st 2023. GMOD is a scintillation-based instrument with a cerium bromide crystal coupled to an array of sixteen silicon photomultipliers, designed for the detection of GRBs. The characterisation of GMOD in the spacecraft, along with the validation of an updated spacecraft MEGAlib model is presented and this approach can be followed by other CubeSats with similar science goals. The energy resolution of the flight model is 7.07% at 662 keV and the effective area peaks in the tens to hundreds of keV, making it a suitable instrument for the detection of GRBs. An investigation into the instrument’s angular response is also detailed. The results from this characterisation campaign are a benchmark for the instrument’s performance pre-launch and will be used to compare with the detector’s performance in orbit.
      Citation: Aerospace
      PubDate: 2024-07-15
      DOI: 10.3390/aerospace11070578
      Issue No: Vol. 11, No. 7 (2024)
       
  • Aerospace, Vol. 11, Pages 579: Experimental Determination of Pitch Damping
           Coefficient Using Free Oscillation Method

    • Authors: Ionuț Bunescu, Mihăiță-Gilbert Stoican, Mihai-Vlăduț Hothazie
      First page: 579
      Abstract: This paper outlines an experimental investigation conducted at the INCAS trisonic wind tunnel, focusing on the determination of pitch damping coefficient. The model used for this investigation is the Basic Finner Model, a standard model for dynamic tests which consists in a cone-cylinder body with four rectangular fins. The study aims to evaluate the influence of various parameters—including the Mach number, angle of attack, reduced frequency, center of rotation, and roll angle—on pitch damping coefficient. The employed method for determining these coefficients is the free oscillation method which consists in measuring the model oscillation in free stream after an initial perturbation. In order to perform these dynamic tests in the wind tunnel, a dedicated rig was developed to initiate the model’s oscillation using a linear servo-actuator and to record its oscillation using a strain gauge. The results obtained from the experiments illustrate how each parameter impacts the pitch damping coefficient, highlighting the precision of the measurements. The paper’s conclusion presents that the developed rig and the method used provide accurate results, and the variation in different parameters can change the damping coefficient.
      Citation: Aerospace
      PubDate: 2024-07-16
      DOI: 10.3390/aerospace11070579
      Issue No: Vol. 11, No. 7 (2024)
       
  • Aerospace, Vol. 11, Pages 580: Rapid and Near-Analytical Planning Method
           for Entry Trajectory under Time and Full-State Constraints

    • Authors: Wenjie Xia, Peichen Wang, Xunliang Yan, Bei Hong, Xinguo Li
      First page: 580
      Abstract: A rapid trajectory-planning method based on an analytical predictor–corrector design of drag acceleration profile and a bank-reversal logic based on double-stage adaptive adjustment is proposed to solve the entry issue under time and full-state constraints. First, an analytical predictor–corrector algorithm is used to design the profile parameters to satisfy the terminal of altitude, velocity, range, time, and flight-path angle constraints. Subsequently, an adaptive lateral planning algorithm based on heading adjustment and maintenance is proposed to achieve the flight stage adaptive division and determination of the bank-reversal point, thereby satisfying the terminal position and heading angle constraints. Concurrently, a rapid quantification method is proposed for the adjustable capacity boundary of the terminal heading angle. On this basis, a range-and-time correction strategy is designed to achieve high precision and the rapid generation of a three-degree-of-freedom entry trajectory under large-scale lateral maneuvering. The simulation results demonstrated that compared with the existing methods, the proposed method can adaptively divide flight stages, ensuring better multitask applicability and higher computational efficiency.
      Citation: Aerospace
      PubDate: 2024-07-16
      DOI: 10.3390/aerospace11070580
      Issue No: Vol. 11, No. 7 (2024)
       
  • Aerospace, Vol. 11, Pages 581: Air Traffic Control Speech Enhancement
           Method Based on Improved DNN-IRM

    • Authors: Yuezhou Wu, Pengfei Li, Siling Zhang
      First page: 581
      Abstract: The quality of air traffic control speech is crucial. However, internal and external noise can impact air traffic control speech quality. Clear speech instructions and feedback help optimize flight processes and responses to emergencies. The traditional speech enhancement method based on a deep neural network and ideal ratio mask (DNN-IRM) is prone to distortion of the target speech in a strong noise environment. This paper introduces an air traffic control speech enhancement method based on an improved DNN-IRM. It employs LeakyReLU as an activation function to alleviate the gradient vanishing problem, improves the DNN network structure to enhance the IRM estimation capability, and adjusts the IRM weights to reduce noise interference in the target speech. The experimental results show that, compared with other methods, this method improves the perceptual evaluation of speech quality (PESQ), short-term objective intelligibility (STOI), scale-invariant signal-to-noise ratio (SI-SNR), and speech spectrogram clarity. In addition, we use this method to enhance real air traffic control speech, and the speech quality is also improved.
      Citation: Aerospace
      PubDate: 2024-07-16
      DOI: 10.3390/aerospace11070581
      Issue No: Vol. 11, No. 7 (2024)
       
  • Aerospace, Vol. 11, Pages 582: Architecture Preliminary Design and
           Trade-Off Optimization of Stratospheric Airship Based on MBSE

    • Authors: Weihao Lyu, Yanchu Yang, Jinggang Miao, Shenghong Cao, Lingsen Kong
      First page: 582
      Abstract: System architecture design is crucial for forward design in aerostat system engineering, yet a comprehensive research framework has been lacking. This paper presents a new method for stratospheric airship architecture preliminary design and optimization trade-off, grounded in Model-Based Systems Engineering (MBSE) theory. Firstly, a requirement analysis for a stratospheric airship is conducted using SysML, leading to the analysis and acquisition of the airship’s mission architecture design. Additionally, a multidisciplinary coupling simulation platform is developed with MATLAB, and the architecture preliminary design’s Pareto front is derived using the NSGA-II algorithm. Finally, based on the Pareto optimization set, the TOPSIS algorithm is applied to derive the optimal architecture preliminary design scheme for the airship. The optimization results validate the accuracy of the architecture preliminary design obtained from the requirement analysis, the reliability of the multidisciplinary coupling simulation platform, and the feasibility of the optimization algorithms. This comprehensive study spans the requirement analysis to the optimal architecture scheme, providing theoretical reference and design guidance for the forward design of airship systems engineering.
      Citation: Aerospace
      PubDate: 2024-07-16
      DOI: 10.3390/aerospace11070582
      Issue No: Vol. 11, No. 7 (2024)
       
  • Aerospace, Vol. 11, Pages 583: A Time-Domain Calculation Method for Gust
           Aerodynamics in Flight Simulation

    • Authors: Zexuan Yang, Chao Yang, Daxin Wen, Wenbo Zhou, Zhigang Wu
      First page: 583
      Abstract: Gusts have a significant impact on aircraft and need to be analyzed through flight simulations. The solution for time-domain gust aerodynamic forces stands as a pivotal stage in this process. With the increasing demand for flight simulations within gusty environments, traditional methods related to gust aerodynamics cannot fail to balance computational accuracy and efficiency. A method that can be used to quickly and accurately calculate the time-domain gust aerodynamic force is needed. This study proposes the fitting strip method, a gust aerodynamic force solution method that is suitable for real-time flight simulations. It only requires the current and previous gust information to calculate the aerodynamic force and is suitable for different configurations of aircraft and different kinds of gusts. Firstly, the fitting strip method requires the division of fitting strips and the calculation of the aerodynamic force under calibration conditions. In this study, the double-lattice method and computational fluid dynamics are used to calculate the aerodynamic force of the strips. Then, the amplitude coefficients and time-delay coefficients are obtained through a fitting calculation. Finally, the coefficients and gust information are put into the formula to calculate the gust aerodynamic force. An example of a swept wing is used for validation, demonstrating congruence between the computational results and experimental data across subsonic and transonic speeds, which proves the accuracy of the fitting strip method in both discrete gusts and continuous gusts. Compared with other methods, the fitting strip method uses the shortest time. Furthermore, the results of a calculation for normal-layout aircraft show that this method avoids the shortcomings of the rational function approximation method and is more accurate than the gust grouping method. Concurrently, gust aerodynamic force calculations were performed on aircraft with large aspect ratios and used in a real-time flight simulation.
      Citation: Aerospace
      PubDate: 2024-07-16
      DOI: 10.3390/aerospace11070583
      Issue No: Vol. 11, No. 7 (2024)
       
  • Aerospace, Vol. 11, Pages 584: A Method for Air Route Network Planning of
           Urban Air Mobility

    • Authors: Jie Li, Di Shen, Fuping Yu, Duo Qi
      First page: 584
      Abstract: Urban air mobility is an effective solution to address the current issue of ground traffic congestion in future cities. However, as the user scale continues to expand, the current civil aviation flight scheduling and control methods are becoming inadequate to meet the high-volume flight guarantee demands of future urban air transportation. In order to effectively handle and resolve potential issues in this field in the future, this paper proposes a method for planning urban air mobility route networks. The planning process is divided into two stages: construction and optimization. Methods for constructing urban air mobility route networks based on flight routes and global optimization methods based on node movement are proposed in each stage. In the construction stage, a complete construction process is designed to generate routes based on existing flight routes, in line with the trend of urban air transportation development. In the optimization stage, inspired by the ant colony algorithm, node transfer rules and information transfer rules are incorporated to design a global optimization process and algorithm for route networks. Experimental results demonstrate the effectiveness and advancement of the proposed planning method.
      Citation: Aerospace
      PubDate: 2024-07-16
      DOI: 10.3390/aerospace11070584
      Issue No: Vol. 11, No. 7 (2024)
       
  • Aerospace, Vol. 11, Pages 585: Cooling of 1 MW Electric Motors through
           Submerged Oil Impinging Jets for Aeronautical Applications

    • Authors: Giuseppe Di Lorenzo, Diego Giuseppe Romano, Antonio Carozza, Antonio Pagano
      First page: 585
      Abstract: Electrification of aircraft is a very challenging task as the demand for energy and power is high. While the storage and generation of electrical energy are widely studied due to the limited specific energy and specific power of batteries and fuel cells, electric machines (power electronics and motors) which have years of experience in many industrial fields must be improved when applied to aviation: they generally have a high efficiency but the increase in power levels determines significant thermal loads which, unlike internal combustion engines (ICE), cannot be rejected with the exhaust. There is therefore a need for thermal management systems (TMSs) with the main objective of maintaining operating temperatures below the maximum level required by electric machines. Turboprop aircraft, such as the ATR 72 or the Dash 8-Q400, are commonly used for regional transport and are equipped with two gas turbine engines whose combined power is in the order of 4 MW. Electric and hybrid propulsion systems for these aircraft are being studied by several leading commercial aviation industries and start-ups, and the 1MW motor size seems to be the main option as it could be used in different aircraft configurations, particularly those that exploit distributed electric propulsion. With reference to the topics mentioned above, the present work presents the design of a TMS for a high-power motor/generator whose electrical architecture is known. Once integrated with the electrical part, the TMS must allow a weight/power ratio of 14 kW/kg (or 20 kW/kg at peak power) while maintaining the temperature below the limit temperature with reasonable safety margins. Submerged jet oil is the cooling technique here applied with a focus on diathermic oil. Parameters affecting cooling, like rotor speed and filling factor, are analysed with advanced CFD.
      Citation: Aerospace
      PubDate: 2024-07-17
      DOI: 10.3390/aerospace11070585
      Issue No: Vol. 11, No. 7 (2024)
       
  • Aerospace, Vol. 11, Pages 586: Airfoil Design Optimization of Blended Wing
           Body for Various Aerodynamic and Stealth Stations

    • Authors: Wei Zhang, Lin Zhou, Ke Zhao, Ruibin Zhang, Zhenghong Gao, Bowen Shu
      First page: 586
      Abstract: The airfoil is the foundation of an aircraft, and its characteristics have a significant impact on those of the aircraft. Conventional airfoil design mainly focuses on improving aerodynamic performance, while flying wing airfoil designs should also consider layout stability and stealth performance. The design requirements for an airfoil vary with its position on the flying wing layout aircraft based on corresponding spanwise flow field characteristics. By analyzing the spanwise flow characteristics of the flying wing, partition design models for flying wing airfoils were established in this study, and a series of flying wing airfoil designs that consider aerodynamics and aerodynamic/stealth were implemented. Then, the designed airfoils were configured on a three-dimensional X-47B layout for testing and verification. The results showed that the aerodynamic design and the aerodynamic/stealth design exhibited significant improvements in terms for aerodynamic and longitudinal trimming characteristics. However, the cruise drag performance of the aerodynamic/stealth design was slightly worse than that of the aerodynamic design, although the longitudinal moment trimming characteristics were basically the same. The stealth characteristics of the aerodynamic/stealth design had significant advantages, indicating that there were weak contradictions between the aerodynamic, stealth, and trimming requirements in the design of the flying wing.
      Citation: Aerospace
      PubDate: 2024-07-17
      DOI: 10.3390/aerospace11070586
      Issue No: Vol. 11, No. 7 (2024)
       
  • Aerospace, Vol. 11, Pages 587: Characteristics of Ice Super Saturated
           Regions in Washington, D.C. Airspace (2019–2023)

    • Authors: Kayla Ebright, Lance Sherry
      First page: 587
      Abstract: Contrails are estimated to contribute 2% of the Earth’s anthropogenic global warming. Contrails are ice crystal clouds formed by the emission of soot and water vapor from jet engines in atmospheric conditions known as Ice Super Saturated (ISS) regions. The formation of contrails can be avoided by flying over or under the ISS regions. Aircraft operators/dispatchers and air traffic control need to know the location of ISS regions in a given airspace to flightplan to avoid contrails. This paper describes the statistics for the presence of ISS regions in the airspace over metropolitan Washington, D.C. These statistics can be used to better understand the operational implications for contrail avoidance. Based on the measurements taken from the twice-daily launch of an aerosonde from Sterling, Virginia (adjacent to Washington, D.C.), analysis of five years of data (2019–2023) indicated that this airspace experiences ISS regions 40% of the days. ISS regions were equally likely during daylight hours (26%) than nighttime (27%). The vertical depth of the ISS region averaged 3000 feet but with a median of 2000 feet. The ISS region floor and ceiling varied by season, with an annual average floor of FL330 and ceiling of FL360. The implications of these results on the operations to avoid contrails, limitations, and future work are discussed.
      Citation: Aerospace
      PubDate: 2024-07-17
      DOI: 10.3390/aerospace11070587
      Issue No: Vol. 11, No. 7 (2024)
       
  • Aerospace, Vol. 11, Pages 588: Hybrid Detection Method for Multi-Intent
           Recognition in Air–Ground Communication Text

    • Authors: Weijun Pan, Zixuan Wang, Zhuang Wang, Yidi Wang, Yuanjing Huang
      First page: 588
      Abstract: In recent years, the civil aviation industry has actively promoted the automation and intelligence of control processes with the increasing use of various artificial intelligence technologies. Air–ground communication, as the primary means of interaction between controllers and pilots, typically involves one or more intents. Recognizing multiple intents within air–ground communication texts is a critical step in automating and advancing the control process intelligently. Therefore, this study proposes a hybrid detection method for multi-intent recognition in air–ground communication text. This method improves recognition accuracy by using different models for single-intent texts and multi-intent texts. First, the air–ground communication text is divided into two categories using multi-intent detection technology: single-intent text and multi-intent text. Next, for single-intent text, the Enhanced Representation through Knowledge Integration (ERNIE) 3.0 model is used for recognition; while the A Lite Bidirectional Encoder Representations from Transformers (ALBERT)_Sequence-to-Sequence_Attention (ASA) model is proposed for identifying multi-intent texts. Finally, combining the recognition results from the two models yields the final result. Experimental results demonstrate that using the ASA model for multi-intent text recognition achieved an accuracy rate of 97.84%, which is 0.34% higher than the baseline ALBERT model and 0.15% to 0.87% higher than other improved models based on ALBERT and ERNIE 3.0. The single-intent recognition model achieved an accuracy of 96.23% when recognizing single-intent texts, which is at least 2.18% higher than the multi-intent recognition model. The results indicate that employing different models for various types of texts can substantially enhance recognition accuracy.
      Citation: Aerospace
      PubDate: 2024-07-18
      DOI: 10.3390/aerospace11070588
      Issue No: Vol. 11, No. 7 (2024)
       
  • Aerospace, Vol. 11, Pages 589: New Data-Driven Models of Mass Flow Rate
           and Isentropic Efficiency of Dynamic Compressors

    • Authors: Xiande Fang, Yuxiang Fang, Yang Yang, Zhiqiang He, Bei Yang
      First page: 589
      Abstract: Dynamic compressors are widely used in many industrial sectors, such as air, land, and marine vehicle engines, aircraft environmental control systems (ECS), air-conditioning and refrigeration, gas turbines, gas compression and injection, etc. The data-driven formulas of mass flow rate and isentropic efficiency of dynamic compressors are required for the design, energy analysis, performance simulation, and control- and/or diagnosis-oriented dynamic simulation of such compressors and the related systems. This work develops data-driven models for predicting the performance of dynamic compressors, including empirical models for mass flow rate and isentropic efficiency, which have high prediction accuracy and broad application range. The performance maps of two multi-stage axial compressors of an aero engine and a centrifugal compressor of an aircraft ECS were chosen for evaluation of the existing empirical formulas and testing of the new models. There are 16 empirical models of mass flow rate and 14 empirical models of isentropic efficiency evaluated, and the results show that it is necessary to develop highly accurate empirical formulas both for mass flow rate and isentropic efficiency. With the data-driven method, two empirical models for mass flow rate and one for isentropic efficiency are developed. They are in general form, with some terms removable to make them simple while enhancing their applicability and prediction accuracy. The new models have much higher prediction accuracy than the best existing counterparts. The new mass flow rate models predict for the three compressors a mean absolute relative deviation (MAD) not greater than 1.3%, while the best existing models all have MAD > 2.0%. The new efficiency model predicts for the three compressors an MAD of 1.0%, 0.4%, and 1.9%, respectively, while the best existing model predicts for the three compressors an MAD of 1.8%, 0.8%, and 3.2%, respectively.
      Citation: Aerospace
      PubDate: 2024-07-19
      DOI: 10.3390/aerospace11070589
      Issue No: Vol. 11, No. 7 (2024)
       
  • Aerospace, Vol. 11, Pages 590: Preliminary Sizing of High-Altitude
           Airships Featuring Atmospheric Ionic Thrusters: An Initial Feasibility
           Assessment

    • Authors: Carlo E.D. Riboldi, Marco Belan, Stefano Cacciola, Raffaello Terenzi, Stefano Trovato, Davide Usuelli, Giuseppe Familiari
      First page: 590
      Abstract: When it comes to computing the values of variables defining the preliminary sizing of an airship, a few standardized approaches are available in the existing literature. However, when including a disruptive technology in the design is required, sizing procedures need to be amended, so as to be able to deal with the features of any additional novel item. This is the case of atmospheric ionic thrusters, a promising propulsive technology based on electric power, where thrusters feature no moving parts and are relatively cheap to manufacture. The present contribution proposes modifications to an existing airship design technique, originally conceived accounting for standard electro-mechanical thrusters, so as to cope with the specific features of new atmospheric ionic thrusters. After introducing this design procedure in detail, its potential is tested by showing results from feasibility studies on an example airship intended for a high-altitude mission. Concurrently, the so-obtained results allow the demonstration of the sizing features corresponding to the adoption of atmospheric ionic thrusters at the current level of technology, comparing them to what is obtained for the same mission when employing a standard electro-mechanical propulsion system.
      Citation: Aerospace
      PubDate: 2024-07-19
      DOI: 10.3390/aerospace11070590
      Issue No: Vol. 11, No. 7 (2024)
       
  • Aerospace, Vol. 11, Pages 591: Experimental Investigation of Runback Water
           Flow Behavior on Aero-Engine Rotating Spinners with Different
           Wettabilities

    • Authors: Kuiyuan Ma, Guiping Lin, Haichuan Jin, Xiaobin Shen, Xueqin Bu
      First page: 591
      Abstract: The accumulation of ice on the aero-engine inlet compromises engine safety. Traditional hot air anti-icing systems, which utilize bleed air, require substantial energy, decreasing engine performance and increasing emissions. Superhydrophobic materials have shown potential in reducing energy consumption when combined with these systems. Research indicates that superhydrophobic surfaces on stationary components significantly reduce anti-icing energy consumption by altering runback water flow behavior. However, for rotating aero-engine components, the effectiveness of superhydrophobic surfaces and the influence of surface wettability on runback water flow remain unclear due to centrifugal and Coriolis forces. This study investigates the runback water flow behavior on aero-engine rotating spinner surfaces with varying wettabilities in a straight-flow spray wind tunnel. The results demonstrated that centrifugal force reduces the amount of runback water on the rotating spinner compared to the stationary surface, forming rivulet flows deflected opposite to the direction of rotation. Furthermore, wettability significantly affects the flow characteristics of runback water on rotating surfaces. As the contact angle increases, the liquid water on the rotating spinner transitions from continuous film flow to rivulet and bead-like flows. Notably, the superhydrophobic surface prevents water adhesion, indicating its potential for anti-icing on rotating components. In addition, the interaction between rotational speed and surface wettability enhances the effects, with both increased rotational speed and larger contact angles contributing to higher liquid water flow velocities, promoting the rapid formation and detachment of rivulet and bead-like flows.
      Citation: Aerospace
      PubDate: 2024-07-20
      DOI: 10.3390/aerospace11070591
      Issue No: Vol. 11, No. 7 (2024)
       
  • Aerospace, Vol. 11, Pages 592: On the Generalization Capability of a
           Data-Driven Turbulence Model by Field Inversion and Machine Learning

    • Authors: Yasunari Nishi, Andreas Krumbein, Tobias Knopp, Axel Probst, Cornelia Grabe
      First page: 592
      Abstract: This paper discusses the generalizability of a data-augmented turbulence model with a focus on the field inversion and machine learning approach. It is highlighted that the augmented model based on two-dimensional (2D) separated airfoil flows gives poor predictive capability for a different class of separated flows (NASA wall-mounted hump) compared to the baseline model due to extrapolation. We demonstrate a sensor-based approach to localize the data-driven model correction to tackle this generalizability issue. Furthermore, the applicability of the augmented model to a more complex aeronautical three-dimensional case, the NASA Common Research Model configuration, is studied. Observations on the pressure coefficient predictions and the model correction field suggest that the present 2D-based augmentation is to some extent applicable to a three-dimensional aircraft flow.
      Citation: Aerospace
      PubDate: 2024-07-20
      DOI: 10.3390/aerospace11070592
      Issue No: Vol. 11, No. 7 (2024)
       
  • Aerospace, Vol. 11, Pages 593: Experimental Study of the Aerodynamic
           Performance and Flow Characteristics of an Integrated UAV Inlet with
           Double 90° Bends

    • Authors: Jiahao Ren, Zhenlong Wu, Huijun Tan, Ziyun Wang, Xiaoming He, Dongpo Li, Yi Zhou
      First page: 593
      Abstract: Many UAVs today have an S-bend inlet for the sake of stealth; however, the majority of them have a relatively gentle transition of the flow channel. This study presents an experimental investigation of the aerodynamic performance and swirl flow characteristics of a UAV inlet with double 90° bends, which is also integrated with an aircraft fuselage as well as a volute. The influences of angle of attack, sideslip angle, AIP Mach number and freestream speed are explored in detail. The influences of the deflectors installed ahead of the first 90° bend of the inlet and the baffle installed at the bottom of the volute are revealed. It is found that both the deflectors and the baffle are beneficial in enhancing the aerodynamic performance of the inlet and alleviating the intensity of the swirl flow inside the volute.
      Citation: Aerospace
      PubDate: 2024-07-21
      DOI: 10.3390/aerospace11070593
      Issue No: Vol. 11, No. 7 (2024)
       
  • Aerospace, Vol. 11, Pages 594: Optimization Study of Steady-State
           Aerial-Towed Cable Circling Strategy Based on BP Neural Network Prediction
           

    • Authors: Luqi Feng, Xueqiang Liu, Zi Feng Nio
      First page: 594
      Abstract: This paper presents models for UAV aerial-towed cables in free-end and fixed-end configurations, crucial for tasks like communication and aerial charging. By establishing a quasi steady-state model, computational results on cable shapes are obtained. To accelerate computations, a backpropagation (BP) neural network prediction model is trained, significantly reducing the computation time. An evaluation function has been developed that integrates both aircraft performance and cable shape considerations to evaluate circling parameters across various states. This function integrates techniques such as BP neural networks and particle swarm optimization (PSO) to refine parameters such as velocities and bank angles for both free-end and fixed-end cables. The results show that the BP neural network accurately predicts cable shapes, achieving a maximum error of 5% in towing force and verticality. Additionally, PSO efficiently optimizes circling parameters, thereby enhancing the effectiveness of the evaluation function in identifying optimal solutions. This approach significantly improves the efficiency of determining optimal circling parameters for UAV aerial-towed cables, thereby contributing to their operational efficacy.
      Citation: Aerospace
      PubDate: 2024-07-21
      DOI: 10.3390/aerospace11070594
      Issue No: Vol. 11, No. 7 (2024)
       
  • Aerospace, Vol. 11, Pages 595: Analysis of the Effect of Sampling Probe
           Geometry on Measurement Accuracy in Supersonic Gas Flow

    • Authors: Wanlin Zhang, Yingtao Chen, Yanting Ai, Pengpeng Sha, Xinlong Yang
      First page: 595
      Abstract: The accuracy of sampling of gas components has a significant impact on the measurement of various performance parameters in the combustion chamber of an aero-engine. In order to investigate the effect of the probe geometry of a six-point gas sampling probe on sampling accuracy in supersonic gas flow, a three-dimensional probe gas flow characteristic solution model is established through numerical simulation methods of components of transport and fluid–solid coupling. Probes with three angles of 28°, 30°, and 32° and an optimized conical probe are constructed. The sampling accuracy of the probes with different geometries is compared and evaluated by the deviation of the component volume fraction before and after sampling and the resulting combustion efficiency error. This paper presents a set of calculation methods for solving the relative deviation of volume fraction by an iterative method based on the ideal gas law and the Redlich–Kwong equation (R-K equation). The method is designed to solve the exact component volume fraction problem in the simulation calculation. The study results demonstrate that the 28° and optimized conical probes improve sampling accuracy more effectively than the original 30° structure. The deviation of the volume fractions of the two structures is less than 1.7%, and the combustion efficiency error is less than 0.09%. The developed iterative calculation method can significantly reduce the theoretical calculation error to less than 0.06%. The experimental data of the test bench are in good agreement with the simulation results, thereby demonstrating the reliability and accuracy of the sampling probe following structural optimization.
      Citation: Aerospace
      PubDate: 2024-07-21
      DOI: 10.3390/aerospace11070595
      Issue No: Vol. 11, No. 7 (2024)
       
  • Aerospace, Vol. 11, Pages 596: Comparative Study on Mechanical Response in
           Rigid Pavement Structures of Static and Dynamic Finite Element Models

    • Authors: Qiao Meng, Ke Zhong, Yuchun Li, Mingzhi Sun
      First page: 596
      Abstract: The safety of airport runways is important to guarantee aircraft taking-off, landing, and taxiing, and the comparison of the mechanical response of pavement structures under dynamic and static loading by LS-DYNA has rarely been studied. The purpose of this work is to separate two analysis methods to investigate the mechanical response of rigid airport pavements. Firstly, a tire–road coupling model of an airfield was established to evaluate the suitability of dynamic and static analyses. Then, the effects of landing pitch angles, sinking speeds, and tire pressures on the effective stress, effective strain, and z-displacement of the runway were investigated for both dynamic and static analysis. Finally, the significance of influence factors was analyzed by regression analysis in Statistical Product and Service Solutions (SPSS). The results indicated that the effective stress, effective strain, and z-displacement of the runway increased with a decrease in the landing pitch angle, which also increased with an increase in the sinking speed and tire pressure. It was demonstrated that the difference in pavement mechanical response between dynamic and static analyses progressively widened at high tire pressure and sinking speed. In other words, the static analysis method can be adopted to assess the dynamic mechanical behavior when the landing pitch angle is large and the tire pressure is small. Among the various factors of mechanical response, the effect of tire pressure was the most obvious, followed by sinking speed and landing pitch angle. The work proposes a new approach to understanding the mechanical behavior of runways under complicated and varied conditions, evaluates the applicability of the dynamic and static mechanical analysis methods, identifies key factors in the dynamic and static mechanical analysis of rigid runways, and provides technical support for improving and maintaining the impact resistance of pavement facilities.
      Citation: Aerospace
      PubDate: 2024-07-22
      DOI: 10.3390/aerospace11070596
      Issue No: Vol. 11, No. 7 (2024)
       
  • Aerospace, Vol. 11, Pages 597: Integrated Waverider Forebody/Inlet Fusion
           Method Based on Discrete Point Cloud Reconstruction

    • Authors: Zhiqi Liu, Geling Yin, Mingqiang Luo, Jinrong Zhang, Cheekeat Heng
      First page: 597
      Abstract: The integrated design of waverider forebodies and inlets is considered a critical challenge in high Mach number vehicle development. To facilitate the rapid construction of integrated geometrical models for waverider forebodies and inlets during the conceptual design phase, a method based on discrete point cloud reconstruction has been proposed. In this method, the geometries of the waverider body and inlet are used as inputs and decomposed into the point cloud under discrete rules. This point cloud is refitted to generate new section lines, which are then lofted into an integrated shape under the constraints of guide curves. By modifying the coordinates of the point cloud positions, the geometric configuration of the integrated shape can be rapidly adjusted, providing initial support for subsequent aerodynamic optimization and thermal protection. Using this method, an integrated approach was applied to a waverider forebody and inward-turning inlet in a tandem configuration. This achieved body-inlet matching and integration, resulting in a 15.6% improvement in the inlet’s total pressure recovery coefficient. The integration time was reduced to just 3.18% of the time required for traditional manual adjustments. Additionally, optimization based on the discrete point cloud enhanced the lift-to-drag ratio by 7.83%, demonstrating the feasibility of the proposed method.
      Citation: Aerospace
      PubDate: 2024-07-22
      DOI: 10.3390/aerospace11070597
      Issue No: Vol. 11, No. 7 (2024)
       
  • Aerospace, Vol. 11, Pages 598: Safe and Efficient Exploration Path
           Planning for Unmanned Aerial Vehicle in Forest Environments

    • Authors: Youkyung Hong, Suseong Kim, Youngsun Kwon, Sanghyouk Choi, Jihun Cha
      First page: 598
      Abstract: This study presents an enhanced exploration path planning for unmanned aerial vehicles. The primary goal is to increase the chances of survival of missing people in forest environments. Exploration path planning is an essential methodology for exploring unknown three-dimensional spaces. However, previous studies have mainly focused on underground environments, not forest environments. The existing path planning methods for underground environments are not directly applicable to forest environments. The reason is that multiple open spaces exist with various obstacles, such as trees, foliage, undergrowth, and rocks. This study mainly focused on improving the safety and efficiency to be suitable for forests rather than underground environments. Paths closer to obstacles are penalized to enhance safety, encouraging exploration at a safer distance from obstacles. A potential field function is applied based on explored space to minimize overlapping between existing and new paths to increase efficiency. The proposed exploration path planning method was validated through an extensive simulation analysis and comparison with state-of-the-art sampling-based path planning. Finally, a flight experiment was conducted to verify further the feasibility of the proposed method using onboard real hardware implementation in a cluttered and complex forest environment.
      Citation: Aerospace
      PubDate: 2024-07-22
      DOI: 10.3390/aerospace11070598
      Issue No: Vol. 11, No. 7 (2024)
       
  • Aerospace, Vol. 11, Pages 599: ATC-SD Net: Radiotelephone Communications
           Speaker Diarization Network

    • Authors: Weijun Pan, Yidi Wang, Yumei Zhang, Boyuan Han
      First page: 599
      Abstract: This study addresses the challenges that high-noise environments and complex multi-speaker scenarios present in civil aviation radio communications. A novel radiotelephone communications speaker diffraction network is developed specifically for these circumstances. To improve the precision of the speaker diarization network, three core modules are designed: voice activity detection (VAD), end-to-end speaker separation for air–ground communication (EESS), and probabilistic knowledge-based text clustering (PKTC). First, the VAD module uses attention mechanisms to separate silence from irrelevant noise, resulting in pure dialogue commands. Subsequently, the EESS module distinguishes between controllers and pilots by levying voice print differences, resulting in effective speaker segmentation. Finally, the PKTC module addresses the issue of pilot voice print ambiguity using text clustering, introducing a novel flight prior knowledge-based text-related clustering model. To achieve robust speaker diarization in multi-pilot scenarios, this model uses prior knowledge-based graph construction, radar data-based graph correction, and probabilistic optimization. This study also includes the development of the specialized ATCSPEECH dataset, which demonstrates significant performance improvements over both the AMI and ATCO2 PROJECT datasets.
      Citation: Aerospace
      PubDate: 2024-07-22
      DOI: 10.3390/aerospace11070599
      Issue No: Vol. 11, No. 7 (2024)
       
  • Aerospace, Vol. 11, Pages 600: Case Study of Along-Track Separation
           Maintenance of Distributed Synthetic Aperture Radar Systems in Low Earth
           Orbits

    • Authors: Marco D’Errico
      First page: 600
      Abstract: Parasitic SAR formation can be flown at low altitude using smaller satellites and adding potential to conventional SAR mission From the orbital point of view, the main issue is related to the differential aerodynamic drag, which rapidly disrupts the formation. In this ambit, this paper proposes a case study of an along-track distributed parasitic receiver flying in formation with PLATiNO-1. Formation maintenance is the core contribution, highlighting how the active control of both altitude and in-plane anomalies leads to an unfeasible ΔV. Then, the active control of the altitude around the nominal value, which naturally controls anomaly shift, is proposed, modeled, and applied to the presented case study. It is shown that the annual ΔV can be reduced to the m/s range.
      Citation: Aerospace
      PubDate: 2024-07-22
      DOI: 10.3390/aerospace11070600
      Issue No: Vol. 11, No. 7 (2024)
       
  • Aerospace, Vol. 11, Pages 564: A Review of Training Procedures for
           Simulated Engine Failure after Take-Off Exercises with Twin-Engine
           Aircraft under 5700 ft

    • Abstract: Engine failure after take-off (or one engine being inoperative) is an exercise conducted as part of multi-engine flight training and on-going competency checking. To prepare pilots to manage a real in-flight emergency, this exercise has traditionally been conducted immediately after take-off. This has led to increased risks of fatal accidents due to the reduced height at which these exercises are typically conducted. Yet, there is variation in the heights stipulated in training procedures published by different stakeholders worldwide. Additionally, the conduct of the exercise has resulted in fatal accidents worldwide. This paper aims to review the previous literature on aviation training and aviation occurrence data to determine what empirical data exists to support the method of conducting simulated engine failures. Peer-reviewed academic publications on aviation training, aviation occurrence databases such as aviation investigation reports, and guidance materials published by aviation authorities on simulated training exercises will be included in this paper. It was found that the previous research on these exercises has focused on the transfer of motion cues or pilot responses to abnormal situations, but did not include specific data comparing pilot performance at different heights above ground level. A review of aviation occurrences found that actual engine failures occurred at higher heights that those used in simulated engine failures. A comparison of the guidance published by aviation authorities identified variations in the minimum altitude published and differing justifications for the minimum height chosen. Future research is needed to compare pilot performance during simulated engine failures to determine the ideal height to conduct the exercise to be representative of an actual engine failure while maintaining safety margins.
      PubDate: 2024-07-10
       
 
JournalTOCs
School of Mathematical and Computer Sciences
Heriot-Watt University
Edinburgh, EH14 4AS, UK
Email: journaltocs@hw.ac.uk
Tel: +00 44 (0)131 4513762
 


Your IP address: 18.97.14.88
 
Home (Search)
API
About JournalTOCs
News (blog, publications)
JournalTOCs on Twitter   JournalTOCs on Facebook

JournalTOCs © 2009-
JournalTOCs
 
 
  Subjects -> MEDICAL SCIENCES (Total: 8186 journals)
    - ALLERGOLOGY AND IMMUNOLOGY (205 journals)
    - ANAESTHESIOLOGY (105 journals)
    - CARDIOVASCULAR DISEASES (334 journals)
    - CHIROPRACTIC, HOMEOPATHY, OSTEOPATHY (19 journals)
    - COMMUNICABLE DISEASES, EPIDEMIOLOGY (227 journals)
    - DENTISTRY (266 journals)
    - DERMATOLOGY AND VENEREOLOGY (162 journals)
    - EMERGENCY AND INTENSIVE CRITICAL CARE (121 journals)
    - ENDOCRINOLOGY (149 journals)
    - FORENSIC SCIENCES (43 journals)
    - GASTROENTEROLOGY AND HEPATOLOGY (178 journals)
    - GERONTOLOGY AND GERIATRICS (125 journals)
    - HEMATOLOGY (160 journals)
    - HYPNOSIS (4 journals)
    - INTERNAL MEDICINE (178 journals)
    - LABORATORY AND EXPERIMENTAL MEDICINE (90 journals)
    - MEDICAL GENETICS (58 journals)
    - MEDICAL SCIENCES (2230 journals)
    - NURSES AND NURSING (331 journals)
    - OBSTETRICS AND GYNECOLOGY (199 journals)
    - ONCOLOGY (355 journals)
    - OPHTHALMOLOGY AND OPTOMETRY (135 journals)
    - ORTHOPEDICS AND TRAUMATOLOGY (150 journals)
    - OTORHINOLARYNGOLOGY (76 journals)
    - PATHOLOGY (96 journals)
    - PEDIATRICS (254 journals)
    - PHYSICAL MEDICINE AND REHABILITATION (153 journals)
    - PSYCHIATRY AND NEUROLOGY (800 journals)
    - RADIOLOGY AND NUCLEAR MEDICINE (182 journals)
    - RESPIRATORY DISEASES (109 journals)
    - RHEUMATOLOGY (76 journals)
    - SPORTS MEDICINE (77 journals)
    - SURGERY (388 journals)
    - UROLOGY, NEPHROLOGY AND ANDROLOGY (151 journals)

HEMATOLOGY (160 journals)                     

Showing 1 - 123 of 123 Journals sorted alphabetically
Acta Angiologica     Open Access   (Followers: 3)
Adipocyte     Open Access  
Advances in Hematology     Open Access   (Followers: 13)
Africa Sanguine     Full-text available via subscription  
American Journal of Hematology     Hybrid Journal   (Followers: 46)
Anemia     Open Access   (Followers: 6)
Annals of Hematology     Hybrid Journal   (Followers: 14)
Arteriosclerosis, Thrombosis and Vascular Biology     Full-text available via subscription   (Followers: 25)
Artery Research     Hybrid Journal   (Followers: 4)
Artificial Cells, Nanomedicine and Biotechnology     Hybrid Journal   (Followers: 3)
ASAIO Journal     Hybrid Journal   (Followers: 3)
Best Practice & Research Clinical Haematology     Hybrid Journal   (Followers: 5)
Blood     Hybrid Journal   (Followers: 317)
Blood Advances     Open Access   (Followers: 9)
Blood and Lymphatic Cancer : Targets and Therapy     Open Access   (Followers: 7)
Blood Cancer Journal     Open Access   (Followers: 21)
Blood Cells, Molecules, and Diseases     Hybrid Journal   (Followers: 5)
Blood Coagulation & Fibrinolysis     Hybrid Journal   (Followers: 27)
Blood Pressure     Open Access   (Followers: 1)
Blood Pressure Monitoring     Hybrid Journal   (Followers: 2)
Blood Reviews     Hybrid Journal   (Followers: 20)
BMJ Open Diabetes Research & Care     Open Access   (Followers: 24)
Bone Marrow Transplantation     Hybrid Journal   (Followers: 15)
British Journal of Haematology     Hybrid Journal   (Followers: 54)
Canadian Journal of Diabetes     Hybrid Journal   (Followers: 9)
Case Reports in Hematology     Open Access   (Followers: 10)
Clinical and Applied Thrombosis/Hemostasis     Open Access   (Followers: 28)
Clinical Diabetes     Full-text available via subscription   (Followers: 30)
Clinical Diabetes and Endocrinology     Open Access   (Followers: 14)
Clinical Lymphoma & Myeloma     Full-text available via subscription   (Followers: 2)
Conquest : The Official Journal of Diabetes Australia     Full-text available via subscription   (Followers: 1)
Current Angiogenesis     Hybrid Journal   (Followers: 1)
Current Diabetes Reports     Hybrid Journal   (Followers: 14)
Current Diabetes Reviews     Hybrid Journal   (Followers: 13)
Current Hematologic Malignancy Reports     Hybrid Journal   (Followers: 2)
Current Opinion in Hematology     Hybrid Journal   (Followers: 14)
Cytotherapy     Full-text available via subscription   (Followers: 1)
Der Diabetologe     Hybrid Journal  
Diabetes     Full-text available via subscription   (Followers: 309)
Diabetes aktuell     Hybrid Journal   (Followers: 2)
Diabetes and Vascular Disease Research     Hybrid Journal   (Followers: 8)
Diabetes Care     Full-text available via subscription   (Followers: 314)
Diabetes Case Reports     Open Access  
Diabetes Educator     Hybrid Journal   (Followers: 10)
Diabetes Research and Clinical Practice     Hybrid Journal   (Followers: 19)
Diabetes Spectrum     Full-text available via subscription   (Followers: 14)
Diabetes Technology & Therapeutics     Hybrid Journal   (Followers: 8)
Diabetes Therapy     Open Access   (Followers: 13)
Diabetic Foot & Ankle     Open Access   (Followers: 9)
Diabetic Medicine     Hybrid Journal   (Followers: 92)
Diabetologia     Hybrid Journal   (Followers: 114)
Diabetologie und Stoffwechsel     Hybrid Journal  
Egyptian Journal of Hematology and Bone Marrow Transplantation     Open Access   (Followers: 9)
eJHaem     Open Access   (Followers: 1)
European Journal of Haematology     Hybrid Journal   (Followers: 12)
Experimental Hematology     Hybrid Journal   (Followers: 3)
Experimental Hematology & Oncology     Open Access   (Followers: 6)
Expert Review of Hematology     Hybrid Journal   (Followers: 4)
Fluids and Barriers of the CNS     Open Access   (Followers: 1)
Haematologica - the Hematology journal     Open Access   (Followers: 35)
Haemophilia     Hybrid Journal   (Followers: 15)
Hematologia     Full-text available via subscription   (Followers: 3)
Hematology     Open Access   (Followers: 9)
Hematology, Transfusion and Cell Therapy     Open Access   (Followers: 2)
Hemodialysis International     Hybrid Journal   (Followers: 3)
Hepatitis Monthly     Open Access   (Followers: 3)
Immunohematology : Journal of Blood Group Serology and Molecular Genetics     Hybrid Journal   (Followers: 3)
Indian Journal of Hematology and Blood Transfusion     Hybrid Journal   (Followers: 1)
Info Diabetologie     Full-text available via subscription  
InFo Hämatologie + Onkologie : Interdisziplinäre Fortbildung von Ärzten für Ärzte     Full-text available via subscription  
Integrated Blood Pressure Control     Open Access   (Followers: 1)
International Blood Research & Reviews     Open Access  
International Journal of Clinical Transfusion Medicine     Open Access   (Followers: 3)
International Journal of Diabetes in Developing Countries     Hybrid Journal   (Followers: 5)
International Journal of Diabetes Research     Open Access   (Followers: 6)
International Journal of Hematology     Hybrid Journal   (Followers: 3)
International Journal of Hematology Research     Open Access   (Followers: 2)
International Journal of Laboratory Hematology     Hybrid Journal   (Followers: 24)
JMIR Diabetes     Open Access  
Journal of Applied Hematology     Open Access   (Followers: 2)
Journal of Blood Medicine     Open Access  
Journal of Cerebral Blood Flow & Metabolism     Hybrid Journal   (Followers: 3)
Journal of Diabetes     Open Access   (Followers: 12)
Journal of Diabetes and its Complications     Hybrid Journal   (Followers: 13)
Journal of Diabetes and Metabolic Disorders     Open Access   (Followers: 6)
Journal of Diabetes Investigation     Open Access   (Followers: 6)
Journal of Diabetes Mellitus     Open Access   (Followers: 4)
Journal of Hematological Malignancies     Open Access  
Journal of Hematology and Transfusion Medicine     Open Access   (Followers: 1)
Journal of Hematopathology     Hybrid Journal   (Followers: 3)
Journal of Pediatric Hematology/Oncology     Hybrid Journal   (Followers: 6)
Journal of Social Health and Diabetes     Open Access  
Journal of Thrombosis and Haemostasis     Hybrid Journal   (Followers: 52)
Journal of Thrombosis and Thrombolysis     Hybrid Journal   (Followers: 30)
Leukemia     Hybrid Journal   (Followers: 23)
Leukemia and Lymphoma     Hybrid Journal   (Followers: 13)
Leukemia Research     Hybrid Journal   (Followers: 9)
Leukemia Research Reports     Open Access   (Followers: 1)
Leukemia Supplements     Full-text available via subscription  
Nederlands Tijdschrift voor Diabetologie     Hybrid Journal  
Nutrition & Diabetes     Open Access   (Followers: 18)
Oncohematology     Open Access   (Followers: 1)
Open Diabetes Journal     Open Access  
Open Hematology Journal     Open Access   (Followers: 1)
Open Hypertension Journal     Open Access  
Open Journal of Blood Diseases     Open Access  
Pediatric Blood & Cancer     Hybrid Journal   (Followers: 6)
Pediatric Hematology Oncology Journal     Open Access   (Followers: 3)
Peritoneal Dialysis International     Hybrid Journal  
Plasmatology     Open Access   (Followers: 1)
Platelets     Hybrid Journal   (Followers: 2)
Practical Diabetes     Hybrid Journal   (Followers: 4)
Primary Care Diabetes     Hybrid Journal   (Followers: 16)
Research and Practice in Thrombosis and Haemostasis     Open Access   (Followers: 2)
Revista Cubana de Hematología, Inmunología y Hemoterapia     Open Access  
Seminars in Hematology     Hybrid Journal   (Followers: 9)
Seminars in Thrombosis and Hemostasis     Hybrid Journal   (Followers: 28)
The Lancet Haematology     Full-text available via subscription   (Followers: 43)
Therapeutic Advances in Hematology     Hybrid Journal  
Thrombosis & Haemostasis     Hybrid Journal   (Followers: 105)
Thrombosis Research     Hybrid Journal   (Followers: 30)
Transplantation and Cellular Therapy     Hybrid Journal   (Followers: 11)
Veins and Lymphatics     Open Access   (Followers: 1)

           

Similar Journals
Similar Journals
HOME > Browse the 73 Subjects covered by JournalTOCs  
SubjectTotal Journals
 
 
JournalTOCs
School of Mathematical and Computer Sciences
Heriot-Watt University
Edinburgh, EH14 4AS, UK
Email: journaltocs@hw.ac.uk
Tel: +00 44 (0)131 4513762
 


Your IP address: 18.97.14.88
 
Home (Search)
API
About JournalTOCs
News (blog, publications)
JournalTOCs on Twitter   JournalTOCs on Facebook

JournalTOCs © 2009-