Journal Cover Aerospace Science and Technology
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   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1270-9638
   Published by Elsevier Homepage  [3118 journals]
  • Three-dimensional salvo attack guidance considering communication delay
    • Authors: Shaoming He; Mingu Kim; Tao Song; Defu Lin
      Pages: 1 - 9
      Abstract: Publication date: February 2018
      Source:Aerospace Science and Technology, Volume 73
      Author(s): Shaoming He, Mingu Kim, Tao Song, Defu Lin
      This paper investigates the problem of salvo attack guidance law design for multiple missiles against a stationary target considering communication delay. The proposed guidance law requires no information on time-to-go and consists of two guidance stages. More specifically, a simple decentralized midcourse guidance law is proposed to provide desired initial conditions for the latter phase. As for the second guidance phase, all missiles are switched to classical pure proportional navigation guidance law. Considering the fact that the communication delay is inevitable in real applications, the corresponding allowed maximum upper bound of the communication delay among all interceptors is also derived analytically. Nonlinear numerical simulations clearly confirm the effectiveness of the proposed formulation.

      PubDate: 2017-12-12T17:56:50Z
      DOI: 10.1016/j.ast.2017.11.019
      Issue No: Vol. 73 (2017)
       
  • Characterisation of turbine behaviour for an engine overspeed prediction
           model
    • Authors: Lucas Pawsey; David John Rajendran; Vassilios Pachidis
      Pages: 10 - 18
      Abstract: Publication date: February 2018
      Source:Aerospace Science and Technology, Volume 73
      Author(s): Lucas Pawsey, David John Rajendran, Vassilios Pachidis
      This paper focuses on the characterisation of turbine overspeed behaviour to be integrated into an engine overspeed model capable of predicting the terminal speed of the high pressure turbine (HPT) in the event of a high pressure shaft failure. The engine considered in this study features a single stage HPT with a shrouded contra-rotating rotor with respect to the single stage intermediate pressure turbine (IPT). The HPT performance is characterised in terms of torque and mass flow function for a range of expansion ratios at various non-dimensional rotational speeds (NH), up to 200% of the design value. Additionally, for each HPT expansion ratio and NH, the change in capacity of the downstream IPT, for different IPT non-dimensional rotational speeds (NI), also needs to be characterised due to the extremely positive incidence angle of the flow from the upstream rotor. An automated toolkit is developed to generate these characteristic maps for both the HPT and IPT. An unlocated high pressure shaft failure will result in rearward movement of the rotor sub-assembly. This causes changes in the rotor tip and rim seal regions, and in the rim seal leakage flow properties. Therefore, in the present work, a high fidelity characterisation of turbine behaviour with the inclusion of tip and rim seals is carried out at three different displacement locations, 0 mm, 10 mm and 15 mm, to improve terminal speed estimation. Furthermore, there is a possibility of damage to the tip seal fins of the HPT rotor due to unbalance in the spool that may result in contact between the rotor aerofoil tip and the casing. Consequently, another set of characteristics are generated with damaged tip fins at each displacement location. It is observed from the characteristics that the torque of the HPT rotor decreases with increasing NH. The HPT mass flow function initially decreases and then increases with an increase in NH. The IPT mass flow function initially remains similar and then decreases with increase in NH above values of 150%. The HPT rotor torque and IPT mass flow function decrease with rearward movement of the HPT rotor sub-assembly for all values of NH. With worn tip seal fins all parameters mentioned previously are lower than in the nominal undamaged case. The high fidelity characterisation of turbines that follows the sequence of events after a shaft failure, as described in this work, can provide accurate predictions of terminal speed and thus act as a tool for testing design modifications that can result in better management and control of the over-speed event.

      PubDate: 2017-12-12T17:56:50Z
      DOI: 10.1016/j.ast.2017.11.037
      Issue No: Vol. 73 (2017)
       
  • Development of the ILR-33 “Amber” sounding rocket for
           microgravity experimentation
    • Authors: Blazej Marciniak; Adam Okninski; Bartosz Bartkowiak; Michal Pakosz; Kamil Sobczak; Wojciech Florczuk; Damian Kaniewski; Jan Matyszewski; Pawel Nowakowski; Dawid Cieslinski; Grzegorz Rarata; Pawel Surmacz; Dominik Kublik; Damian Rysak; Jaromir Smetek; Piotr Wolanski
      Pages: 19 - 31
      Abstract: Publication date: February 2018
      Source:Aerospace Science and Technology, Volume 73
      Author(s): Blazej Marciniak, Adam Okninski, Bartosz Bartkowiak, Michal Pakosz, Kamil Sobczak, Wojciech Florczuk, Damian Kaniewski, Jan Matyszewski, Pawel Nowakowski, Dawid Cieslinski, Grzegorz Rarata, Pawel Surmacz, Dominik Kublik, Damian Rysak, Jaromir Smetek, Piotr Wolanski
      This paper gives an overview of the development of the ILR-33 ”Amber” sounding rocket designated for microgravity experiments, that is under development at Institute of Aviation in Warsaw, Poland. The lack of an easily accessible and affordable platform for this kind of research was one of the key reasons for this work. The proposed design enables performing experiments in microgravity for almost 150 seconds with an apogee over 100 km. Combining these results with a relatively low price per launch and short deployment time gives a possibility to establish a firm position on the dynamic market. This article describes also the rocket structure and the vehicle's capabilities. The proposed design utilizes a hybrid rocket motor with High Test Peroxide as an oxidizer along with two reusable solid rocket boosters. The early phase analysis of the rocket configuration and propellant considerations are also presented in the paper. Furthermore, there have been already several on-ground test performed such as: wind tunnel research and motor firings. The proposed design is considered as an introduction to small launch vehicle technology.

      PubDate: 2017-12-12T17:56:50Z
      DOI: 10.1016/j.ast.2017.11.034
      Issue No: Vol. 73 (2017)
       
  • Conceptual design of a Blended Wing Body MALE UAV
    • Authors: P. Panagiotou; S. Fotiadis-Karras; K. Yakinthos
      Pages: 32 - 47
      Abstract: Publication date: February 2018
      Source:Aerospace Science and Technology, Volume 73
      Author(s): P. Panagiotou, S. Fotiadis-Karras, K. Yakinthos
      The current work is an aerodynamic design study of a Blended Wing Body (BWB) Medium-Altitude-Long-Endurance (MALE) Unmanned-Aerial-Vehicle (UAV). Using a combined approach of presizing tools and computational simulations, a step-by-step layout design study was conducted to define the key layout characteristics and select the optimal airframe-engine combination. Trade studies were also carried out to optimize the aerodynamic performance and stability. The traditional sizing and aerodynamic estimation methods were adopted to incorporate the characteristics of the BWB platform, whereas CFD computations were employed in order to calculate the aerodynamic and stability coefficients, during the layout comparison and trade studies. Drawings and tables are provided to show the progression of the design study at each stage. The performance specifications are also compared with a conventional UAV platform to point out the main advantages and disadvantages of the BWB for MALE UAV applications.

      PubDate: 2017-12-12T17:56:50Z
      DOI: 10.1016/j.ast.2017.11.032
      Issue No: Vol. 73 (2017)
       
  • Fault detection in operating helicopter drivetrain components based on
           support vector data description
    • Authors: V. Camerini; G. Coppotelli; S. Bendisch
      Pages: 48 - 60
      Abstract: Publication date: February 2018
      Source:Aerospace Science and Technology, Volume 73
      Author(s): V. Camerini, G. Coppotelli, S. Bendisch
      The objective of the paper is to develop a vibration-based automated procedure dealing with early detection of mechanical degradation of helicopter drive train components using Health and Usage Monitoring Systems (HUMS) data. An anomaly-detection method devoted to the quantification of the degree of deviation of the mechanical state of a component from its nominal condition is developed. This method is based on an Anomaly Score (AS) formed by a combination of a set of statistical features correlated with specific damages, also known as Condition Indicators (CI), thus the operational variability is implicitly included in the model through the CI correlation. The problem of fault detection is then recast as a one-class classification problem in the space spanned by a set of CI, with the aim of a global differentiation between normal and anomalous observations, respectively related to healthy and supposedly faulty components. In this paper, a procedure based on an efficient one-class classification method that does not require any assumption on the data distribution, is used. The core of such an approach is the Support Vector Data Description (SVDD), that allows an efficient data description without the need of a significant amount of statistical data. Several analyses have been carried out in order to validate the proposed procedure, using flight vibration data collected from a H135, formerly known as EC135, servicing helicopter, for which micro-pitting damage on a gear was detected by HUMS and assessed through visual inspection. The capability of the proposed approach of providing better trade-off between false alarm rates and missed detection rates with respect to individual CI and to the AS obtained assuming jointly-Gaussian-distributed CI has been also analysed.

      PubDate: 2017-12-27T04:58:02Z
      DOI: 10.1016/j.ast.2017.11.043
      Issue No: Vol. 73 (2017)
       
  • “Wasted performance” minimization of the multi-purpose mini-satellite
           platform for an EO mission using a dynamic simulation-based model
    • Authors: Asad Saghari; Shima Rahmani; Amirreza Kosari; Masoud Ebrahimi
      Pages: 61 - 77
      Abstract: Publication date: February 2018
      Source:Aerospace Science and Technology, Volume 73
      Author(s): Asad Saghari, Shima Rahmani, Amirreza Kosari, Masoud Ebrahimi
      With growing interest in low-cost, high performance and short time-to-flight satellites, the idea of using multi-purpose satellite platforms has drawn many attentions. However, under certain conditions in which the required capability of a mission is slightly more than the capabilities of a specified variant of a multi-purpose platform, it must jump to the next higher capability variant. Correspondingly, lots of unnecessary performance or capability might be imposed. In this paper, the main goal is to minimize the wasted performance in the design of an Earth Observation (EO) satellite based on a multi-purpose platform. To this end, a dynamic simulation-based model has been developed with the capability of simulating the satellite performance characteristics, EO mission requirements and supportable performance by the platform under various circumstances and throughout the satellite lifetime. To minimize the wasted performance we face with an optimization problem containing a complicated non-linear, non-convex and multi-modal design space which is enveloped by constraints of the mission requirements and supportable performance of the platform. A novel criterion as an objective function has been introduced aiming at the incompatibility reduction between the capabilities of a certain multi-purpose platform variant and the EO mission requirements. This objective function considers all the performance variations during the entire mission lifetime rather than solely the worst case. Through this, the mission and orbital characteristics have been determined by which there would be no need to jump to the higher performance variant in order to satisfy the EO mission requirements.

      PubDate: 2017-12-27T04:58:02Z
      DOI: 10.1016/j.ast.2017.11.038
      Issue No: Vol. 73 (2017)
       
  • Ignition delay kinetic model of boron particle based on bidirectional
           diffusion mechanism
    • Authors: Daolun Liang; Jianzhong Liu; Yunan Zhou; Junhu Zhou; Kefa Cen
      Pages: 78 - 84
      Abstract: Publication date: February 2018
      Source:Aerospace Science and Technology, Volume 73
      Author(s): Daolun Liang, Jianzhong Liu, Yunan Zhou, Junhu Zhou, Kefa Cen
      Ignition delay time of B particles is one of the key factors that influence their burnout ratio in the afterburner. In this study, the micro/nanofabricated slice measurement of a combustion residue particle of B was carried out. By combining the experimental results obtained with previous experimental results, the surface diffusion mechanism of a single B particle was completely verified. Then, an ignition delay kinetic model of B particle was developed using the principles of semiempirical models. By ensuring the initial ignition temperature, the ignition delay of a single B particle can be divided into two stages: (i) heat transfer stage and (ii) low-temperature oxidation stage. The existence of both O2 diffusion and (BO) n diffusion (bidirectional diffusion) was confirmed during the low-temperature oxidation stage. Only heat transfer between the B particle and surroundings occurred during the heat transfer stage, whereas both heat transfer and oxidation occurred during the low-temperature oxidation stage. The oxidation involves four global reactions: (i) evaporation of B2O3, (ii) diffusion of O2, (iii) diffusion of (BO) n , and (iv) reaction of H2O. The final ignition delay time of a B particle is equal to the sum of the lasting times of heat transfer stage and low-temperature oxidation stage. The results of computed ignition delay time obtained by the model are consistent with the previous experimental data under O2/H2O atmosphere. According to the prediction of the model, the increase in the initial particle size will prolong the ignition delay time of a B particle. The ignition delay of a small B particle is dominated by the low-temperature oxidation stage, whereas the ignition delay of a large B particle is dominated by the heat transfer stage.

      PubDate: 2017-12-27T04:58:02Z
      DOI: 10.1016/j.ast.2017.11.044
      Issue No: Vol. 73 (2017)
       
  • Civil turbofan engine exhaust aerodynamics: Impact of bypass nozzle
           after-body design
    • Authors: Ioannis Goulos; Tomasz Stankowski; David MacManus; Philip Woodrow; Christopher Sheaf
      Pages: 85 - 95
      Abstract: Publication date: February 2018
      Source:Aerospace Science and Technology, Volume 73
      Author(s): Ioannis Goulos, Tomasz Stankowski, David MacManus, Philip Woodrow, Christopher Sheaf
      It is envisaged that the next generation of civil large turbofan engines will be designed for greater bypass ratios when compared to contemporary architectures. The underlying motivation is to reduce specific thrust and improve propulsive efficiency. Concurrently, the aerodynamic performance of the exhaust system is anticipated to play a key role in the success of future engine architectures. The transonic flow topology downstream of the bypass nozzle can be significantly influenced by the after-body geometry. This behavior is further complicated by the existence of the air-flow vent on the nozzle after-body which can have an impact on the performance of the exhaust system. This paper aims to investigate the aerodynamics associated with the geometry of the bypass nozzle after-body and to establish guidelines for the design of separate-jet exhausts with respect to future large turbofan engines. A parametric geometry definition has been derived based on Class-Shape Transformation (CST) functions for the representation of post-nozzle-exit components such as after-bodies, plugs, and air-flow vents. The developed method has been coupled with an automatic mesh generation and a Reynolds Averaged Navier–Stokes (RANS) flow solution method, thus devising an integrated aerodynamic design tool. A cost-effective optimization strategy has been implemented consisting of methods for Design Space Exploration (DSE), Response Surface Modeling (RSM), and Genetic Algorithms (GAs). The combined approach has been deployed to explore the aerodynamic design space associated with the bypass nozzle after-body geometry for a Very High Bypass Ratio (VHBR) turbofan engine with separate-jet exhausts. A detailed investigation has been carried out to expose the transonic flow mechanisms associated with the effect of after-body curvature combined with the impact of the air-flow vent. A set of optimum curved after-body geometries has been obtained, with each subsequently compared against their respective conical representation. The obtained results suggest that no significant performance improvements can be obtained through curving the nozzle after-body relative to the case of a conical design. However, it is shown that the application of surface curvature has the potential to unlock new parts in the design space that allow analysts to reduce the required after-body length without any loss in aerodynamic performance. The developed approach complements the existing tool-set of enabling technologies for the design and optimization of future large aero-engines, consequently leading to increased thrust and reduced Specific Fuel Consumption (SFC).

      PubDate: 2017-12-27T04:58:02Z
      DOI: 10.1016/j.ast.2017.09.002
      Issue No: Vol. 73 (2017)
       
  • An analytical study of the vibroacoustic response of a ribbed plate
    • Authors: Tao Fu; Zhaobo Chen; Hongying Yu; Chengfei Li; Xiaoxiang Liu
      Pages: 96 - 104
      Abstract: Publication date: February 2018
      Source:Aerospace Science and Technology, Volume 73
      Author(s): Tao Fu, Zhaobo Chen, Hongying Yu, Chengfei Li, Xiaoxiang Liu
      An analytical model is developed to investigate the sound transmission loss from orthogonally rib-stiffened plates structure under diffuse acoustic field excitation. The validity and feasibility of the model are verified by comparing the present theoretical predictions with numerical and experimental results published previously. The influences of modal coupling terms, boundary condition and stiffener spacing on sound power and sound transmission loss are subsequently presented. Numerical discussion of the model demonstrates the significant influence of both boundary conditions and stiffener spacing upon the mode shape, sound power and sound transmission loss for stiffened plate, wherein sound power decreases and sound transmission loss increases as the amount of constraint increases.

      PubDate: 2017-12-12T17:56:50Z
      DOI: 10.1016/j.ast.2017.11.047
      Issue No: Vol. 73 (2017)
       
  • A combined criteria-based method for hypersonic three-dimensional boundary
           layer transition prediction
    • Authors: Ling Zhou; Rui Zhao; Renfu Li
      Pages: 105 - 117
      Abstract: Publication date: February 2018
      Source:Aerospace Science and Technology, Volume 73
      Author(s): Ling Zhou, Rui Zhao, Renfu Li
      In this paper, a new method for predicting hypersonic three-dimensional (3D) boundary layer transition is developed. It is based on the Re θ / M e criterion for streamwise instability and on the Re cf , new criterion for crossflow instability. An intermittency function is also formulated and applied to combine laminar and turbulent flows. Additionally, a computational grid pretreating method, compatible with modern computational fluid dynamics (CFD) techniques based on parallel execution is adopted in order to obtain the boundary layer parameters. Four criteria are compared to define the boundary layer edge. A HIFiRE-5 elliptic cone at different Reynolds numbers is adopted to validate the performance of the criteria-based transition model and the effectiveness of the four criteria for boundary layer edge definition. The results show that the boundary layer edge of complex hypersonic 3D flows could be obtained properly with the computational grid pretreating method and the combination of h 0 / h 0 , ∞ = 0.995 and ( d u / d H ) / ( d u / d H ) w = 0.1 criteria. Moreover, the computed Re θ / M e and Re cf , new distributions in the region between the leading edge and the centerline are similar to the N-factor for streamwise and crossflow instabilities from linear parabolized stability equation (PSE) methods. The shape and trend of the transition onsets predicted by the criteria-based transition model between the centerline and leading edge of HIFiRE-5 agree well with the experiment. However, as for the transition on the centerline, which is dominated by the inflection point in streamwise velocity profiles, using the criteria-based transition model related to boundary layer thickness would predict the transition onset prematurely.

      PubDate: 2017-12-27T04:58:02Z
      DOI: 10.1016/j.ast.2017.12.002
      Issue No: Vol. 73 (2017)
       
  • Improved rotor aeromechanics predictions using a fluid structure
           interaction approach
    • Authors: Younghyun You; Deokhwan Na; Sung N. Jung
      Pages: 118 - 128
      Abstract: Publication date: February 2018
      Source:Aerospace Science and Technology, Volume 73
      Author(s): Younghyun You, Deokhwan Na, Sung N. Jung
      The measured HART (Higher harmonic control Aeroacoustic Rotor Test) I data in a descending flight condition is validated using various numerical approaches including CFD (Computational Fluid Dynamics)–CSD (Computational Structural Dynamics) coupled analyses with isolated rotor model and rotor-fuselage model. A CSD-alone approach is also conducted for reference purpose. A three-dimensional (3D) compressible RANS (Reynolds Averaged Navier Stokes) flow solver is employed for the CFD code. Good convergence behavior is found for both coupling analyses. It is observed that the rotor-fuselage model improves the correlation significantly as compared with the measured data. Specifically, the highly oscillating section normal forces signals marked in the advancing and retreating sides of the rotor are captured accurately. Detailed harmonic analysis and the gradient of the airloads signals are observed to prove the validity of the prediction model. The upwash induced due to a fuselage as well as the increased vorticity over the rotor flow fields are attributed to the enhanced correlation. The predicted blade elastic motions and structural moments also indicate improvements with the present rotor-fuselage model.

      PubDate: 2017-12-27T04:58:02Z
      DOI: 10.1016/j.ast.2017.11.041
      Issue No: Vol. 73 (2017)
       
  • First-order shear deformation theory for orthotropic doubly-curved shells
           based on a modified couple stress elasticity
    • Authors: Farajollah Zare Jouneghani; Payam Mohammadi Dashtaki; Rossana Dimitri; Michele Bacciocchi; Francesco Tornabene
      Pages: 129 - 147
      Abstract: Publication date: February 2018
      Source:Aerospace Science and Technology, Volume 73
      Author(s): Farajollah Zare Jouneghani, Payam Mohammadi Dashtaki, Rossana Dimitri, Michele Bacciocchi, Francesco Tornabene
      This paper investigates the micro- and nano-mechanical behavior of orthotropic doubly-curved shells by considering the New Modified Couple Stress Theory (NMCST). The higher order continuum assumed by the NMCST includes three material length scale parameters in order to capture the size-effect of anisotropic and orthotropic materials. The governing equations of the problem are based on the First-order Shear Deformation Theory (FSDT). According to the proposed NMCST, the expressions of the physical components for the strain and curvature tensors are obtained in an orthogonal curvilinear coordinate system. Then, the governing differential equations and boundary conditions are derived by applying the energy method and Hamilton's principle. A comparative investigation between our numerical results and the ones available in the literature proves the capability of the proposed formulation in predicting the micro- and nano-mechanical behavior of orthotropic doubly-curved shells.

      PubDate: 2017-12-27T04:58:02Z
      DOI: 10.1016/j.ast.2017.11.045
      Issue No: Vol. 73 (2017)
       
  • An efficient single-loop strategy for reliability-based multidisciplinary
           design optimization under non-probabilistic set theory
    • Authors: Xiaojun Wang; Ruixing Wang; Lei Wang; Xianjia Chen; Xinyu Geng
      Pages: 148 - 163
      Abstract: Publication date: February 2018
      Source:Aerospace Science and Technology, Volume 73
      Author(s): Xiaojun Wang, Ruixing Wang, Lei Wang, Xianjia Chen, Xinyu Geng
      Non-probabilistic reliability based multidisciplinary design optimization (NRBMDO) offers a powerful tool for making reliable decisions with the consideration of uncertain-but-bounded uncertainties for complex engineering systems. However, the prohibitive computation and convergence difficulties caused by the directly coupling of uncertainty based multidisciplinary analysis (UMDA), non-probabilistic reliability analysis (NRA) and MDO would seriously hamper the application of NRBMDO. In this paper, an efficient single loop strategy for NRBMDO (SLS_NRBMDO) is developed to decouple the nested issue and thus improve the computational efficiency. The key idea of the proposed strategy is decoupling NRBMDO with several cycles of sequential MDO, UMDA, NRA and translating distance calculation (TDC). For UMDA, three methods, i.e., the first order interval Taylor expansion method, the interval vertex theorem, the direct optimization approach are formulated. Besides, NRA is conducted on the basis of the expanded non-probabilistic stress–strength interference model and the volume ratio thought, which provides a clear and definite assessment criterion for the structural safety with uncertain-but-bounded parameters. Furthermore, the translating strategy based on the performance measure approach is proposed to shift and update the constraints, and the expression of the translating distance is mathematically derived to accelerate the design procedure. Eventually, the effectiveness and efficiency of the proposed method are illustrated with one numerical case and one practical supersonic wing optimization design problem.

      PubDate: 2017-12-27T04:58:02Z
      DOI: 10.1016/j.ast.2017.11.046
      Issue No: Vol. 73 (2017)
       
  • An experimental study of surface wettability effects on dynamic ice
           accretion process over an UAS propeller model
    • Authors: Yang Liu; Linkai Li; Haixing Li; Hui Hu
      Pages: 164 - 172
      Abstract: Publication date: February 2018
      Source:Aerospace Science and Technology, Volume 73
      Author(s): Yang Liu, Linkai Li, Haixing Li, Hui Hu
      An experimental study was conducted to evaluate the effects of surface wettability on the dynamic ice accretion process over the surface of a rotating Unmanned-Aerial-System (UAS) propeller model and the resultant aerodynamic performance degradation due to the ice accretion. A propeller model was installed in an Icing Research Tunnel at Iowa State University (i.e., ISU-IRT) with its surface wettability changed significantly (i.e., hydrophilic surface versus superhydrophobic surface). In addition to acquiring “phase-locked” images to reveal the dynamic ice accretion process over the rotating propeller surface, the thrust generation and the required power input to drive the propeller model to operate at a constant rotation speed were also measured during the ice accretion process. The dynamic ice accretion process over the rotating propeller surface was found to vary remarkably with changes to the propeller surface wettability. By making the propeller surface superhydrophobic, the detrimental effects of the ice accretion on the aerodynamic performance of the propeller model were found to be mitigated greatly with much less ice accretion over the propeller surface, significant reduction of the thrust loss and less demand for extra power consumption due to the ice accretion, in comparison with the case with the propeller surface being hydrophilic.

      PubDate: 2017-12-27T04:58:02Z
      DOI: 10.1016/j.ast.2017.12.003
      Issue No: Vol. 73 (2017)
       
  • UAV collision avoidance exploitation for noncooperative trajectory
           modification
    • Authors: Pietro Pierpaoli; Amir Rahmani
      Pages: 173 - 183
      Abstract: Publication date: February 2018
      Source:Aerospace Science and Technology, Volume 73
      Author(s): Pietro Pierpaoli, Amir Rahmani
      Distributed collision-free trajectories are generally obtained through a continuous sharing of information between vehicles. With the intent of investigating possible sources of vulnerability in autonomous frameworks, we formalize a procedure malicious players can follow to influence other. In this paper we propose a strategy for steering a UAV towards predetermined targets. The strategy described here relies on the existence of a flight information sharing protocol (i.e. ADS-B) and predictable collision avoidance algorithms. A model predictive controller is applied to the switching system representing a pair of UAVs coupled by the presence of an imminent collision. As showed by means of numerical simulations and robot experiments, the result is a loss of autonomy on the UAV. Our results suggest the need to include the subject of our study in the discussion on safe automated airspace.

      PubDate: 2017-12-27T04:58:02Z
      DOI: 10.1016/j.ast.2017.12.008
      Issue No: Vol. 73 (2017)
       
  • Maximum likelihood principle and moving horizon estimation based adaptive
           unscented Kalman filter
    • Authors: Bingbing Gao; Shesheng Gao; Gaoge Hu; Yongmin Zhong; Chengfan Gu
      Pages: 184 - 196
      Abstract: Publication date: February 2018
      Source:Aerospace Science and Technology, Volume 73
      Author(s): Bingbing Gao, Shesheng Gao, Gaoge Hu, Yongmin Zhong, Chengfan Gu
      The classical unscented Kalman filter (UKF) requires prior knowledge on statistical characteristics of system noises for state estimation of a nonlinear dynamic system. If the statistical characteristics of system noises are unknown or inaccurate, the UKF solution will be deteriorated or even divergent. This paper presents a novel adaptive UKF by combining the maximum likelihood principle (MLP) and moving horizon estimation (MHE) to overcome this limitation. This method constructs an optimization based estimation of system noise statistics according to MLP. Subsequently, it further establishes a moving horizon strategy to improve the computational efficiency of the MLP based optimization estimation. Based on above, a new expectation maximization technique is developed to iteratively compute the MLP and MHE based noise statistic estimation by replacing complex smoothed estimates with filtering estimates for further improvement of the computational efficiency. The proposed method can achieve the online estimation of system noise statistic and enhance the robustness of the classical UKF. The efficacy of the proposed adaptive UKF is demonstrated through simulations and practical experiments in the INS/GPS integrated navigation.

      PubDate: 2017-12-27T04:58:02Z
      DOI: 10.1016/j.ast.2017.12.007
      Issue No: Vol. 73 (2017)
       
  • Fault-tolerant adaptive finite-time attitude synchronization and tracking
           control for multi-spacecraft formation
    • Authors: Chengxi Zhang; Jihe Wang; Dexin Zhang; Xiaowei Shao
      Pages: 197 - 209
      Abstract: Publication date: February 2018
      Source:Aerospace Science and Technology, Volume 73
      Author(s): Chengxi Zhang, Jihe Wang, Dexin Zhang, Xiaowei Shao
      This paper addresses the attitude synchronization and tracking control (ASTC) for multi-spacecraft formation system (MFS) under undirected and directed graph. First, a new adaptive nonsingular fast terminal sliding mode surface (ANFTSMS) is developed. It has both the merits of the NFTSM avoiding singularity and the adaptive method regulating the relative weighting of parameters. This provides designers a new way to improve the control performance. Second, by applying ANFTSMS, the proposed ANFTSM-controllers (ANFTSMCs) provide high precision finite-time convergence, robust to time-varying disturbances, uncertainties and accommodate to actuator faults, limited inputs. Moreover, the ANFTSMCs also achieve simple structure, inexpensive computations and chattering-free for continuous design. Few studies have addressed these problems simultaneously. Finally, effectiveness of the algorithms are verified via simulations.

      PubDate: 2017-12-27T04:58:02Z
      DOI: 10.1016/j.ast.2017.12.004
      Issue No: Vol. 73 (2017)
       
  • Matching error of the iterative closest contour point algorithm for
           terrain-aided navigation
    • Authors: Kedong Wang; Tongqian Zhu; Yujie Qin; Rui Jiang; Yong Li
      Pages: 210 - 222
      Abstract: Publication date: February 2018
      Source:Aerospace Science and Technology, Volume 73
      Author(s): Kedong Wang, Tongqian Zhu, Yujie Qin, Rui Jiang, Yong Li
      The algorithm used for terrain-aided navigation (TAN) is crucial for high performance of such a totally autonomous and long-duration underwater vehicle navigation technique. This paper presents results of an investigation into the matching errors of the revised iterative closest contour point (ICCP) algorithm for underwater TAN. In particular the quantitative relationship of the matching errors with terrain features is studied in this paper. Among 10 terrain factors, 6 of them have been shown to have the most influence on the accuracy of the revised ICCP algorithm. Three statistical methods, including multiple regression, logistic regression, and discriminant analysis, are applied to mathematically derive the different relationships between the terrain factors and the matching errors. Each formula uses no more than three terrain factors to fit the matching errors. This paper also studies the effect of other factors, including the initial error of the inertial navigation system (INS), the INS accuracy, the map resolution, the vehicle speed, the matching path length, and the sonar accuracy, on the matching errors.

      PubDate: 2017-12-27T04:58:02Z
      DOI: 10.1016/j.ast.2017.12.010
      Issue No: Vol. 73 (2017)
       
  • A three-dimensional predictor–corrector entry guidance based on
           reduced-order motion equations
    • Authors: Liang Zeng; Hongbo Zhang; Wei Zheng
      Pages: 223 - 231
      Abstract: Publication date: February 2018
      Source:Aerospace Science and Technology, Volume 73
      Author(s): Liang Zeng, Hongbo Zhang, Wei Zheng
      A three-dimensional predictor–corrector entry guidance algorithm is proposed in this paper. More accurate solutions of flight path angle and velocity are obtained with the guidance algorithm to reduce the order of motion equations, which greatly lower the amount of calculation for generating on-board three-dimensional trajectories. By planning two bank angle reversals, the burden on attitude control system is significantly reduced and the reliability of the lateral guidance is well guaranteed. Using the developed solutions and integrating the reduced-order motion equations numerically, the three-dimensional trajectory planning problem is transformed into two one-parameter searching problems: one is for the right guidance parameter and the other one is for the bank angle reversal points. Given the guidance parameter and bank angle reversal points, a feasible three-dimensional trajectory can be generated quickly and the guiding commands for the vehicle heading towards the landing site can be directly obtained. By comparing with the actual guided entry trajectory, the feasibility of the planned three-dimensional entry trajectory is evaluated. Though there are some differences between them, the actual trajectory is well approximated with the present method. Additionally, extensive numerical simulations have been carried out to test the validity and robustness of the proposed entry guidance algorithm. The simulation results demonstrate that the entry guidance works well and has a good flexibility.

      PubDate: 2017-12-27T04:58:02Z
      DOI: 10.1016/j.ast.2017.12.009
      Issue No: Vol. 73 (2017)
       
  • Analysis of a distributed estimation and control scheme for formation
           flying spacecraft
    • Authors: Thanh Vu; Amir Rahmani
      Pages: 232 - 238
      Abstract: Publication date: February 2018
      Source:Aerospace Science and Technology, Volume 73
      Author(s): Thanh Vu, Amir Rahmani
      The stability characteristics of a distributed consensus-based Kalman filter estimation and control scheme are studied through analytic and numerical means. This estimation scheme seeks to minimally reduce the necessary bandwidth for communication while maintaining overall stability. A weaker form of the separation principle is proven to hold whereby control could be designed independently but not estimation. However, actuation limitations still provide the possibility for a semi-independent design of estimators. Numerical simulations confirm that the stability depends very heavily on consensus on estimation and ultimately the amount of information available to the system as it evolves.

      PubDate: 2017-12-27T04:58:02Z
      DOI: 10.1016/j.ast.2017.10.028
      Issue No: Vol. 73 (2017)
       
  • Stall margin enhancement of a novel casing treatment subjected to
           circumferential pressure distortion
    • Authors: Xu Dong; Dakun Sun; Fanyu Li; Xiaofeng Sun
      Pages: 239 - 255
      Abstract: Publication date: February 2018
      Source:Aerospace Science and Technology, Volume 73
      Author(s): Xu Dong, Dakun Sun, Fanyu Li, Xiaofeng Sun
      This paper presents the stall margin enhancement of a novel casing treatment subjected to circumferential pressure inlet distortion. Experimental results are carried out on a low-speed compressor. Experimental results show that the stall margin of the test compressor is gravely narrowed by circumferential pressure inlet distortion. The stabilization ability of this novel casing treatment and the pre-stall behavior of the compression system under the impacts of circumferential pressure distortion are shown in the present work. Although subjected to the inlet distortion, the stall margin can also be made up by 6%–8% due to the application of this novel casing treatment. Furthermore, the pre-stall dynamic results can indicate that the mechanism of this stabilization method is associated with two main observations, one is the weakening of the unsteady flow perturbations in the compressor, and the other is the delay in of the nonlinear amplification of the stall precursor waves.

      PubDate: 2017-12-27T04:58:02Z
      DOI: 10.1016/j.ast.2017.12.005
      Issue No: Vol. 73 (2017)
       
  • Influence of swirl number on jet noise reduction using flat vane swirlers
    • Authors: P. Balakrishnan; K. Srinivasan
      Pages: 256 - 268
      Abstract: Publication date: February 2018
      Source:Aerospace Science and Technology, Volume 73
      Author(s): P. Balakrishnan, K. Srinivasan
      In this work, jet noise reduction using a swirling flow surrounding a circular free jet has been demonstrated. The passive control scheme induces swirl from six flat vanes fixed in an annular passage with vane angles from 0 to 50°, with the corresponding swirl numbers ranging from 0 to 0.91. Noise measurements in terms of overall sound pressure levels, directivity patterns, acoustic spectra; and flow measurements in terms of centerline pitot survey and flow visualization have been carried out to evaluate the efficacy of the passive control scheme. The co-axial swirl jets always reduce the low frequency noise, irrespective of the nozzle pressure ratio. The screech tone is entirely eliminated and broadband shock associated noise mitigated by the co-axial swirl jets. The results of highly under expanded supersonic cases, show that, the weak swirl generates higher noise and high swirl generates lower noise for the same nozzle pressure ratio. The centerline pitot pressure measurements reveal that the co-axial swirl jets decrease the core lengths and the number of shock cells compared to the free jet. The flow visualization study shows that Mach disks are generated at lower pressure ratios for the co-axial swirl jets compared to free jet. The present work proposes swirl as an excellent passive tool for jet noise suppression.

      PubDate: 2017-12-27T04:58:02Z
      DOI: 10.1016/j.ast.2017.11.039
      Issue No: Vol. 73 (2017)
       
  • A biobjective branch and bound procedure for planning spatial missions
    • Authors: Dalal Madakat; Jérôme Morio; Daniel Vanderpooten
      Pages: 269 - 277
      Abstract: Publication date: February 2018
      Source:Aerospace Science and Technology, Volume 73
      Author(s): Dalal Madakat, Jérôme Morio, Daniel Vanderpooten
      More than 90% of the space objects orbiting around the earth are space debris. Since the orbits of these debris often overlap the trajectories of spacecraft, they create a potential collision risk. The problem of removing the most dangerous space debris can be modeled as a biobjective time dependent traveling salesman problem (BiTDTSP). In this paper, we study an approach based on a branch and bound procedure to determine the Pareto frontier of the BiTDTSP.

      PubDate: 2017-12-27T04:58:02Z
      DOI: 10.1016/j.ast.2017.11.040
      Issue No: Vol. 73 (2017)
       
  • Effect of pitch down motion on the vortex reformation over fighter
           aircraft
    • Authors: Guoliang Xu; Gang Liu; Xiong Jiang; Weiqi Qian
      Pages: 278 - 288
      Abstract: Publication date: February 2018
      Source:Aerospace Science and Technology, Volume 73
      Author(s): Guoliang Xu, Gang Liu, Xiong Jiang, Weiqi Qian
      The aerodynamic characteristics of a realistic aircraft undergoing high amplitude pitching motions ranging from angle of attack 0° to 80° are studied using a combination of delayed detached eddy simulation (DDES) method and experimental approach with reduced oscillation rates κ = 0.036 , 0.054 and 0.072. According to the DDES-based results and experimental data, it is confirmed that asymmetric vortex structure reformation process can be induced by pitch down motion when sideslip angle β = 0 ° , thereby leading to abrupt and substantial increases in both dynamic normal and side forces. In addition, the effect of pitching frequency on the asymmetric vortex redevelopment is also studied, it will be suppressed with the increase of the oscillation rate, and the bubble and spiral modes are observed to dominate the left and right vortex breakdown process respectively on the left and right upper surface.

      PubDate: 2017-12-27T04:58:02Z
      DOI: 10.1016/j.ast.2017.12.006
      Issue No: Vol. 73 (2017)
       
  • Adaptive backstepping control for air-breathing hypersonic vehicles with
           input nonlinearities
    • Authors: Qinglei Hu; Yao Meng; Chenliang Wang; Youmin Zhang
      Pages: 289 - 299
      Abstract: Publication date: February 2018
      Source:Aerospace Science and Technology, Volume 73
      Author(s): Qinglei Hu, Yao Meng, Chenliang Wang, Youmin Zhang
      This paper addresses the control problem of air-breathing hypersonic vehicles subject to input nonlinearities, aerodynamic uncertainties and flexible modes. An adaptive backstepping controller and a dynamic inverse controller are developed for the altitude subsystem and the velocity subsystem, respectively, where the former eliminates the problem of “explosion of terms” inherent in backstepping control. Moreover, a modified smooth inverse of the dead-zone is proposed to compensate for the dead-zone effects and reduce the computational burden. Based on this smooth inverse, an input nonlinear pre-compensator is designed to handle input saturation and dead-zone nonlinearities, which leads to a simpler control design for the altitude subsystem subject to these two input nonlinearities. It is proved that the proposed controllers can guarantee that all closed-loop signals are bounded and the tracking errors converge to an arbitrarily small residual set. Simulation results are carried out to demonstrate the effectiveness of the proposed control scheme.

      PubDate: 2017-12-27T04:58:02Z
      DOI: 10.1016/j.ast.2017.12.001
      Issue No: Vol. 73 (2017)
       
  • Broadband reduction of the specular reflections by using sonic crystals: A
           proof of concept for noise mitigation in aerospace applications
    • Authors: L.M. Garcia-Raffi; L.J. Salmerón-Contreras; I. Herrero-Durá; R. Picó; J. Redondo; V.J. Sánchez-Morcillo; K. Staliunas; N.J.E. Adkins; A. Cebrecos; N. Jiménez; V. Romero-García
      Pages: 300 - 308
      Abstract: Publication date: February 2018
      Source:Aerospace Science and Technology, Volume 73
      Author(s): L.M. Garcia-Raffi, L.J. Salmerón-Contreras, I. Herrero-Durá, R. Picó, J. Redondo, V.J. Sánchez-Morcillo, K. Staliunas, N.J.E. Adkins, A. Cebrecos, N. Jiménez, V. Romero-García
      The broadband reduction of the specular reflections by sonic crystals (SCs) is theoretically and experimentally reported in this work. The analysed system consists of a sound source radiating a SC made of acoustically rigid scatterers embedded in water partially covering an open cavity. By comparison with a reference flat reflector, we observe that reflected waves spread in space as a consequence of the spatially modulated properties of the SC. Moreover, due to the different working frequency ranges of the SC a significant noise reduction is produced in a broadband region. Therefore, due to the spreading of the reflected waves, the system produces a broadband noise reduction in the area of the source. In particular, the noise reduction is close to 2 dB for the two octaves emitted by our source, which represents a decrease of 37 % of the acoustic energy. The results shown in this work constitute a proof of concept for the use of SCs as broadband-noise reduction systems at the launch pad. An approach to the geometry of the Vega launch vehicle the European Space Agency is proposed and the limitations of the study are discussed.

      PubDate: 2017-12-27T04:58:02Z
      DOI: 10.1016/j.ast.2017.11.048
      Issue No: Vol. 73 (2017)
       
  • Local feature based automatic target recognition for future 3D active
           homing seeker missiles
    • Authors: O. Kechagias-Stamatis; N. Aouf; G. Gray; L. Chermak; M. Richardson; F. Oudyi
      Pages: 309 - 317
      Abstract: Publication date: February 2018
      Source:Aerospace Science and Technology, Volume 73
      Author(s): O. Kechagias-Stamatis, N. Aouf, G. Gray, L. Chermak, M. Richardson, F. Oudyi
      We propose an architecture appropriate for future Light Detection and Ranging (LIDAR) active homing seeker missiles with Automatic Target Recognition (ATR) capabilities. Our proposal enhances military targeting performance by extending ATR into the 3rd dimension. From a military and aerospace industry point of view, this is appealing as weapon effectiveness against camouflage, concealment and deception techniques can be substantially improved. Specifically, we present a missile seeker 3D ATR architecture that relies on the 3D local feature based SHOT descriptor and a dual-role pipeline with a number of pre and post-processing operations. We evaluate our architecture on a number of missile engagement scenarios in various environmental setups with the missile being under various altitudes, obliquities, distances to the target and scene resolutions. Under these demanding conditions, the recognition performance gained is highly promising. Even in the extreme case of reducing the database entries to a single template per target, our interchangeable ATR architecture still provides a highly acceptable performance. Although we focus on future intelligent missile systems, our approach can be implemented to a great range of time-critical complex systems for space, air and ground environments for military, law-enforcement, commercial and research purposes.

      PubDate: 2017-12-27T04:58:02Z
      DOI: 10.1016/j.ast.2017.12.011
      Issue No: Vol. 73 (2017)
       
  • Probe motion compound control for autonomous aerial refueling docking
    • Authors: Zikang Su; Honglun Wang
      Pages: 1 - 13
      Abstract: Publication date: January 2018
      Source:Aerospace Science and Technology, Volume 72
      Author(s): Zikang Su, Honglun Wang
      This paper proposed a probe motion compound control scheme for the receiver docking control in the autonomous aerial refueling (AAR). The dynamic equation of the probe is modeled based on the receiver's 6 DOF nonlinear model which considers the influence of the multiple flow disturbance, and these dynamic equations are transformed into the affine nonlinear form for convenient control design. The AAR docking flight controller is divided into several cascade subsystems via back-stepping design technique. The terms which are independent of the virtual control variables in each affine nonlinear subsystem are taken as the “lumped disturbance”, and are accurately estimated for the disturbance compensation in the designed flight controller, by a group of extended states observers (ESO). Then a compound control scheme, which is constituted by back-stepping and ESO, is proposed for AAR docking based on these established receiver dynamics affine nonlinear form and the estimated lumped disturbances by ESOs. In the proposed probe compound scheme, the probe motion is controlled not only via the translational motion of the barycenter but also via the rotational motion of the receiver. The stability of the proposed probe compound control closed-loop system is formally proved by using Lyapunov function technique. Extensive simulations are carried out to verify the effectiveness and improvement with the proposed controller.

      PubDate: 2017-11-05T08:34:20Z
      DOI: 10.1016/j.ast.2017.10.033
      Issue No: Vol. 72 (2017)
       
  • Mission optimisation for a conceptual coaxial rotorcraft for taxi
           applications
    • Authors: J. Enconniere; J. Ortiz-Carretero; V. Pachidis
      Pages: 14 - 24
      Abstract: Publication date: January 2018
      Source:Aerospace Science and Technology, Volume 72
      Author(s): J. Enconniere, J. Ortiz-Carretero, V. Pachidis
      This paper presents the development and an application of a multidisciplinary methodology for the preliminary design assessment of compound coaxial rotorcraft with a counter-rotating rotor system and a rear-mounted propeller. A comprehensive optimisation strategy is deployed to evaluate the environmental and operational benefits of the aforementioned rotorcraft architecture. The code is validated against experimental data prior to the application of the methodology to the evaluation of a conceptual vehicle for intercity taxi applications. Response Surface Models (RSMs) are generated to mimic the rotorcraft performance in order to accelerate the optimisation process. The effects of the defined mission input parameters such as cruise speed, altitude, climb rate or mission length are evaluated. Pareto fronts for fuel burn, N O x emissions and mission duration are obtained. The method was applied to a hypothetical scenario of mission length ranging from 50 to 300 km. Best estimate mission scenario are selected from the Pareto fronts, providing on average 23%, 20%, and 13% simultaneous reductions in mission duration, fuel burn, and N O x emissions when compared to a conventional flight procedure. The picked scenarios coincide with the fuel optimised mission scenarios for each mission length, thus the multi-disciplinary environment was not required. Besides, an “improved” mission procedure is outlined, defining the mission characteristics independently of the mission's length. This procedure yields on average 22%, 14%, and 8% reductions in mission duration, fuel burn, and N O x emissions, respectively.

      PubDate: 2017-11-05T08:34:20Z
      DOI: 10.1016/j.ast.2017.10.031
      Issue No: Vol. 72 (2017)
       
  • Objective quantification of perceived differences between measured and
           synthesized aircraft sounds
    • Authors: Abhishek K. Sahai; Mirjam Snellen; Dick G. Simons
      Pages: 25 - 35
      Abstract: Publication date: January 2018
      Source:Aerospace Science and Technology, Volume 72
      Author(s): Abhishek K. Sahai, Mirjam Snellen, Dick G. Simons
      This paper presents an approach with which perceived audible differences in aircraft sounds can be quantified and presented in an objective manner. The objective quantification of the subjectively heard audible differences is intended to serve two primary goals. It can firstly enable developers of auralization technology to make the auralized sounds more realistic by identifying in which aspects the synthesized sounds differ from their real-life counterparts and to what extent. The quantification can secondly provide an improved and more detailed means of distinguishing between aircraft sounds in general, beyond the conventional metrics of A-weighted Sound Pressure level (dBA) or Effective Perceived Noise Level (EPNL) used currently to assess aircraft noise. In this study sound quality metrics are used to quantify the differences in aircraft sounds. These metrics are widely used in other industries such as the automotive sector. Audio files of a reference aircraft, made over identical flight paths at a noise monitoring station in the vicinity of Schiphol airport, are compared in terms of both conventional and sound quality metrics for four measured and four auralized audio files. It is observed from the comparison that differences that may appear small in the conventional metrics can be significant in terms of the sound quality metrics. Significant differences in measured and synthesized sounds are observed for the aircraft considered in this study with regards to the tonal content and fluctuations in amplitude that occur over time. The conventional metrics are seen to capture the overall loudness aspect of aircraft sounds, but give no clear information regarding which spectral or temporal characteristics cause the sounds to be perceived as audibly different.

      PubDate: 2017-11-11T08:45:18Z
      DOI: 10.1016/j.ast.2017.10.035
      Issue No: Vol. 72 (2017)
       
  • Attitude controller design for reusable launch vehicles during reentry
           phase via compound adaptive fuzzy H-infinity control
    • Authors: Qi Mao; Liqian Dou; Qun Zong; Zhengtao Ding
      Pages: 36 - 48
      Abstract: Publication date: January 2018
      Source:Aerospace Science and Technology, Volume 72
      Author(s): Qi Mao, Liqian Dou, Qun Zong, Zhengtao Ding
      In this paper, the attitude control problem of reusable launch vehicles (RLVs) during reentry phase is investigated by using compound adaptive fuzzy H-infinity control (CAFHC) strategy in the presence of parameter uncertainties and external disturbances. Firstly, the control-oriented attitude model is established by a model transformation based on the six-degree-of-freedom (6-DoF) dynamic model of the RLV. Secondly, a novel attitude control scheme is developed and the control strategy consists of two parts to achieve a stable and accurate attitude tracking during reentry flight process. An attitude tracking controller is designed utilizing adaptive fuzzy H-infinity control approach combined with an identification model to improve the attitude tracking performance in the interior of fuzzy approximation region of attitude angle. Next, an attitude stabilization controller based on boundary adaptive technique is employed to assure the robustness of the closed-loop system in the exterior of fuzzy approximation region of attitude angle. Furthermore, the stability of the closed-loop system is guaranteed within the framework of Lyapunov theory and the attitude tracking error converges to a small neighborhood around origin. Finally, the simulation results are presented to demonstrate that the effectiveness of the proposed control scheme for reentry RLV, and its tracking performance performs better than the other control method.

      PubDate: 2017-11-11T08:45:18Z
      DOI: 10.1016/j.ast.2017.10.012
      Issue No: Vol. 72 (2017)
       
  • Flow physics and chine control of the water spray generated by an aircraft
           rigid tire rolling on contaminated runways
    • Authors: Kaibin Zhao; Peiqing Liu; Qiulin Qu; Pingchang Ma; Tianxiang Hu
      Pages: 49 - 62
      Abstract: Publication date: January 2018
      Source:Aerospace Science and Technology, Volume 72
      Author(s): Kaibin Zhao, Peiqing Liu, Qiulin Qu, Pingchang Ma, Tianxiang Hu
      During the take-off and landing of aircrafts from/on water-contaminated runways, the tire-generated water spray can endanger flight safety, such as engine spray ingestion and spray impingement drag. In this paper, the flow physics and chine control of the spray generated by an aircraft rigid tire are studied by the Smoothed Particle Hydrodynamics (SPH) method. The SPH method is validated by a NASA experiment. The forming and developing progresses of the front and side sprays are described in detail. It is found that the parabolic stripe of initial ejected particles at a given time is the boundary between the spray source region and the non-disturbed region in water film, and the stripes at any time are similar. The effects of tire speed and water film depth on spray angles are evaluated. The chines can effectively control the spray angles by reducing the vertical velocity component of the ejected particles and increasing the lateral component. The arc chines are more effective in controlling the spray than the linear chines.

      PubDate: 2017-11-11T08:45:18Z
      DOI: 10.1016/j.ast.2017.10.036
      Issue No: Vol. 72 (2017)
       
  • A new approach of casing treatment design for high speed compressors
           running at partial speeds with low speed large scale test
    • Authors: Xi Nan; Ning Ma; Feng Lin; Takehiro Himeno; Toshinori Watanabe
      Pages: 104 - 113
      Abstract: Publication date: January 2018
      Source:Aerospace Science and Technology, Volume 72
      Author(s): Xi Nan, Ning Ma, Feng Lin, Takehiro Himeno, Toshinori Watanabe
      The instability problems tend to be more severe when high speed compressors operate at partial speeds. This paper proposes an economic approach for casing treatment design that suitable to this situation. Aiming at reducing the expensive and time-consuming high-speed casing treatment experiments, the idea of low-speed similitude of high-speed compressors, which was originally practiced in mid-1980 with the purpose of loss reduction, is now extended to simulate the stability enhancement with casing treatment in this paper. The core idea of this approach is to replace a large portion of design processes for the high-speed compressors (the Prototype) with their equivalent large scale model compressors (the Model). Two different transonic rotors with skewed slots and circumferential grooves casing treatments are conducted as examples to demonstrate this approach. Following the selected similarity rules, the Model is firstly acquired by modeling the near stall point of the Prototype. A variety of casing treatments are designed and assessed on the Model. Then a few more promising configurations can thus be selected via low speed experiments. They are believed to have similar tendency on stall margin improvement on the Prototype. Finally, the selected configurations are converted back to the Prototype with based on the rule of similarity and validated by experimental data. In this paper, principles that guarantee the similitude of the flow field at near stall condition and the effectiveness of the casing treatment are discussed.

      PubDate: 2017-11-11T08:45:18Z
      DOI: 10.1016/j.ast.2017.10.032
      Issue No: Vol. 72 (2017)
       
  • Assessment of a hybrid RANS/LES simulation method and URANS method in
           
    • Authors: Yiyu Han; Yuanyuan He; Ye Tian; Fuyu Zhong; Jialing Le
      Pages: 114 - 122
      Abstract: Publication date: January 2018
      Source:Aerospace Science and Technology, Volume 72
      Author(s): Yiyu Han, Yuanyuan He, Ye Tian, Fuyu Zhong, Jialing Le
      A scramjet combustor is simulated using both a hybrid Reynolds averaged Navier–Stokes (RANS)/large eddy simulation (LES) method, namely zonal detached eddy simulation (ZDES), and unsteady RANS (URANS) method to conduct an assessment of their abilities in depicting the unsteady motions of flow structures in the scramjet combustor. Although ZDES and URANS present a similar ability with regard to calculating the mean variables, they present distinct differences concerning the ability to capture the unsteady motions of the flow structures. The ZDES case successfully captures the unsteady motions of the shock structures. The resolved flow is comprised of a series of oscillating cycles that mixes strong cycles and weak cycles, and one or more strong cycles are followed by one or more weak cycles. In strong cycles, the oscillating amplitude of the pressure is large and the duration of cycle is long. The range of the motion of shock structures is large, and a Mach disc is formed when the shock structures move upstream. In weak cycles, the oscillating amplitude of the pressure is small and the duration is short, and no Mach disc appears throughout a cycle. All of these coincide fairly well with the experimental shadowgraph images. In contrast, the results of URANS distinctly disagree with those of the ZDES case and the experiments.

      PubDate: 2017-11-18T08:52:51Z
      DOI: 10.1016/j.ast.2017.11.003
      Issue No: Vol. 72 (2017)
       
  • Lift improvements using duty-cycled plasma actuation at low Reynolds
           numbers
    • Authors: Xuanshi Meng; Haiyang Hu; Xu Yan; Feng Liu; Shijun Luo
      Pages: 123 - 133
      Abstract: Publication date: January 2018
      Source:Aerospace Science and Technology, Volume 72
      Author(s): Xuanshi Meng, Haiyang Hu, Xu Yan, Feng Liu, Shijun Luo
      An experimental study on active flow control over an elliptic airfoil is performed using an alternating-current dielectric-barrier-discharge (AC-DBD) plasma actuator combined with the duty-cycled technique. This study aims to eliminate or decrease the nonlinearities of the lift curves within a range of small angles of attack at low Reynolds numbers. The results of plasma actuator characterization in the quiescent air show that the duty-cycled plasma actuation can generate periodic sustained vortices with strengthened vorticity and streamwise momentum in comparison of steady-on mode. The wind tunnel test results show that the baseline airfoil exhibits the clearer nonlinear behavior at small AOA for lower Reynolds numbers. With duty-cycled plasma actuation, a rigidly linear proportional control of the lift that varies with the AOA is achieved with the reduced frequency f + = 1 . The surface oil-flow measurement shows the plasma actuator can delay the separation and result in an enhanced lift when the laminar boundary layer separation occurs without reattachment. When the long laminar separation bubble appears in the trailing edge region, the plasma actuator can eliminate the bubble. In this case, the extra lift supplied by the bubble is eliminated, leading to a reduced airfoil lift. The linear proportional control of the lift can be achieved by the appropriate enhanced and reduced lift changes which can be supplied by the duty-cycled plasma actuation.

      PubDate: 2017-11-18T08:52:51Z
      DOI: 10.1016/j.ast.2017.10.038
      Issue No: Vol. 72 (2017)
       
  • A novel quasi-3D hyperbolic theory for free vibration of FG plates with
           porosities resting on Winkler/Pasternak/Kerr foundation
    • Authors: Davood Shahsavari; Maryam Shahsavari; Li Li; Behrouz Karami
      Pages: 134 - 149
      Abstract: Publication date: January 2018
      Source:Aerospace Science and Technology, Volume 72
      Author(s): Davood Shahsavari, Maryam Shahsavari, Li Li, Behrouz Karami
      A novel quasi-3D hyperbolic theory is presented for the free vibration analysis of functionally graded (FG) porous plates resting on elastic foundations by dividing transverse displacement into bending, shear, and thickness stretching parts. The elastic foundation can be chosen as Winkler, Pasternak or Kerr foundation. Three different patterns of porosity distributions (including even and uneven distribution patterns, and the logarithmic-uneven pattern) are considered. A Galerkin method is developed for the solution of the eigenvalue problem of the presented quasi-3D hyperbolic plate model. The presented quasi-3D hyperbolic theory is simple and easy to implement since it uses only five-unknown variables to determine fourfold coupled (axial-shear-bending-stretching) vibration responses. A comprehensive parametric study is carried out to assess the effects of volume fraction index, porosity fraction index, stiffness of foundation parameters, mode numbers, and geometry on the natural frequencies of imperfect FG plates.

      PubDate: 2017-11-18T08:52:51Z
      DOI: 10.1016/j.ast.2017.11.004
      Issue No: Vol. 72 (2017)
       
  • Control strategy of sideslip perching maneuver under dynamic stall
           influence
    • Authors: Mir Feroskhan; Tiauw H. Go
      Pages: 150 - 163
      Abstract: Publication date: January 2018
      Source:Aerospace Science and Technology, Volume 72
      Author(s): Mir Feroskhan, Tiauw H. Go
      This paper presents a sliding control strategy for executing a sideslip perching maneuver under dynamic stall influence. Perching is a type of aggressive maneuver performed by the avian species to acquire rapid deceleration, which is frequently followed by a precision landing. Due to the high turn rates and rapid changes in aerodynamic angles in the three-dimensional domain, robustness to state perturbations and model inaccuracies is mandatory as it is impossible to develop a completely accurate aerodynamic model for perching that involves many dynamic phenomena and different flow regimes. Based on the optimal trajectory solutions generated through an optimization procedure, sliding mode control is proposed to address the need for robust tracking in the nonlinear, unsteady region of flight dynamics with the inclusion of dynamic stall delay. Performance of the controller is validated under different scenarios involving varying initial spatial and state conditions and state perturbations throughout the course of the perching maneuver.

      PubDate: 2017-11-18T08:52:51Z
      DOI: 10.1016/j.ast.2017.11.002
      Issue No: Vol. 72 (2017)
       
  • Unconventional hybrid airships design optimization accounting for added
           masses
    • Authors: A. Ceruti; D. Gambacorta; P. Marzocca
      Pages: 164 - 173
      Abstract: Publication date: January 2018
      Source:Aerospace Science and Technology, Volume 72
      Author(s): A. Ceruti, D. Gambacorta, P. Marzocca
      This paper describes the implementation of a framework which can be used to optimize the external shape of an unconventional airship configuration. This framework includes the estimation of Added Masses (AM) which captures the contribution of the dynamic effect related to the acceleration of a body immersed in a fluid having a similar density to that of the body itself. A computationally efficient routine to compute AM has been implemented in a heuristic optimization loop based on a Particle Swarm Optimization (PSO) algorithm, and has been integrated into a simple model which provides hybrid airship's aerodynamics characteristics. As a case study, the take-off distance of a hybrid airship has been optimized by the methodology, and it is used to show the effect on the optimization loop and the errors arising from using conventional approximated AM evaluation methods. The proposed set of simulations clearly evaluates the errors expected on the unconventional airships performances when approximated methods are used in the evaluation of the AM.

      PubDate: 2017-12-12T17:56:50Z
      DOI: 10.1016/j.ast.2017.10.042
      Issue No: Vol. 72 (2017)
       
  • Control oriented modeling and analysis of centrifugal compressor working
           characteristic at variable altitude
    • Authors: Dongdong Zhao; Zhiguang Hua; Manfeng Dou; Yigeng Huangfu
      Pages: 174 - 182
      Abstract: Publication date: January 2018
      Source:Aerospace Science and Technology, Volume 72
      Author(s): Dongdong Zhao, Zhiguang Hua, Manfeng Dou, Yigeng Huangfu
      The centrifugal compressor converting the kinetic energy into the pressure increase has been extensively used for industry applications. Due to its high rotational speed, the volume and weight could be greatly reduced which makes it suitable for in-flight gas compression systems. Combining the high altitude circumstances such as the air density, pressure, temperature, etc., an centrifugal compressor model is first developed in this paper. This model takes the changing properties of the atmosphere, air pressure and air density into account. The working characteristics of the centrifugal compressor at different altitudes are studied. Meanwhile, the effects of the parameter variations on the compressor performance is analyzed. Moreover, dynamics of the air flow and pressure are investigated with varied altitude. A closed loop controller based on super twisting sliding mode approach is proposed to make the mass flow track the reference.

      PubDate: 2017-12-12T17:56:50Z
      DOI: 10.1016/j.ast.2017.11.010
      Issue No: Vol. 72 (2017)
       
  • Vibration suppression of flexible spacecraft during attitude maneuver
           using CMGs
    • Authors: Jitang Guo; Yunhai Geng; Baolin Wu; Xianren Kong
      Pages: 183 - 192
      Abstract: Publication date: January 2018
      Source:Aerospace Science and Technology, Volume 72
      Author(s): Jitang Guo, Yunhai Geng, Baolin Wu, Xianren Kong
      In this paper, control moment gyroscope (CMG) system is employed to suppress vibration of flexible spacecraft during attitude maneuver. Direct modal force generated by CMGs is exerted to elastic dynamics due to interaction between CMGs and flexibilities of structure. A novel control strategy based on a modal force compensator is proposed, which is simple and efficient to reduce vibration during attitude maneuver. The proposed modal force compensator avoids exciting vibration by the means of canceling out disturbance input to elastic dynamics using modal force generated by CMGs. No modal information is required in the modal force compensator. A concept named as modal force singularity is introduced and analyzed in depth. A restriction on gimbal angles is developed to avoid modal force singularity. Subsequently, a steering logic based on pseudo-inverse is proposed to allocate modal force commands without introducing force errors. Numerical simulations are presented to show the effectiveness of the proposed approaches.

      PubDate: 2017-12-12T17:56:50Z
      DOI: 10.1016/j.ast.2017.11.005
      Issue No: Vol. 72 (2017)
       
  • Numerical simulation of unsteady tip clearance flow in a transonic
           compressor rotor
    • Authors: Zhiqiang Wang; Bo Lu; Jiaxin Liu; Jun Hu
      Pages: 193 - 203
      Abstract: Publication date: January 2018
      Source:Aerospace Science and Technology, Volume 72
      Author(s): Zhiqiang Wang, Bo Lu, Jiaxin Liu, Jun Hu
      A three-dimensional, multi-passage unsteady numerical study was conducted to enhance the understanding of unsteady flow phenomena in the tip region of a transonic axial compressor rotor. Two different inlet conditions were applied to the transonic rotor to demonstrate the effect of the inlet condition on the unsteady flow phenomenon in the rotor tip region. The inlet conditions selected were axial inflow and 16-deg of co-swirl. The results show that different inlet conditions lead to different shock wave intensities and positions, which critically affects the unsteady flow structure in the tip region of the transonic rotor. Under the co-swirl inlet condition, the tip leakage vortex of each blade oscillates synchronously at the near stall point because of the weak interaction between the tip leakage vortex and the shock. Under the axial inlet condition, the rotating instability phenomenon appears as the “multi-passage structure,” which propagates along the circumference occurring at the tip of the rotor in the stable operating range due to the strong interaction between the tip leakage vortex and the shock wave. With the decrease of the mass flow, the mode order of the “multi-passage structure” does not change, but the fluctuation frequency decreases gradually.

      PubDate: 2017-12-12T17:56:50Z
      DOI: 10.1016/j.ast.2017.11.012
      Issue No: Vol. 72 (2017)
       
  • Onboard mission planning for agile satellite using modified mixed-integer
           linear programming
    • Authors: Yuchen She; Shuang Li; Yanbin Zhao
      Pages: 204 - 216
      Abstract: Publication date: January 2018
      Source:Aerospace Science and Technology, Volume 72
      Author(s): Yuchen She, Shuang Li, Yanbin Zhao
      This paper investigates a new Agile Earth Observation Satellite (AEOS) mission planning algorithm. This new developed algorithm is based on Modified Mixed-Integer Linear Programming (MILP) approach, which takes the minimum slew angle and highest priority criterion. The key point of the paper lies in that the planning process is treated as a Dynamical Combinatorial Optimization (DCO) problem due to the time-varying constraint and the requirement of the problem. The design of the new algorithm is also to meet the real-time requirement of onboard mission planning. The mathematical formulation of the problem is modified to satisfy the demand of the LP solver, and a newly developed dynamic database is used to simulate the constantly changing satellite-target relative position with limited observation windows. The new mission planning model is solved by the LP method to test its reliability. Another solution with Generic Algorithm (GA) is also given to check the result. The calculation time of these two methods is compared to show that the LP approach has a better compatibility with the onboard mission planning requirement.

      PubDate: 2017-12-12T17:56:50Z
      DOI: 10.1016/j.ast.2017.11.009
      Issue No: Vol. 72 (2017)
       
  • Efficient infinite-swept wing solver for steady and unsteady compressible
           flows
    • Authors: Matteo Franciolini; Andrea Da Ronch; Jernej Drofelnik; Daniella Raveh; Andrea Crivellini
      Pages: 217 - 229
      Abstract: Publication date: January 2018
      Source:Aerospace Science and Technology, Volume 72
      Author(s): Matteo Franciolini, Andrea Da Ronch, Jernej Drofelnik, Daniella Raveh, Andrea Crivellini
      An efficient Navier–Stokes solver for the infinite-swept wing problem is presented. The new flow solution, that reproduces correctly the physics responsible for cross-flow effects, is obtained around a two-dimensional stencil. On the contrary, existing state-of-the-art methods rely on a three-dimensional stencil. Numerical details are followed by an extensive validation campaign, including steady and unsteady compressible flows. The test cases are for single and multi-element aerofoils in both laminar and turbulent regimes. Under identical conditions (numerical settings, grids, etc.), the computational cost of the proposed solver was reduced by at least 75% compared to that of existing state-of-the-art methods. This was also confirmed employing various turbulence models. With a limited effort required to enhance an existing computational fluid dynamics solver (either two or three-dimensional), the infinite-swept wing method was implemented in an industrial-grade package used across Europe for rapid engineering analysis.

      PubDate: 2017-12-12T17:56:50Z
      DOI: 10.1016/j.ast.2017.10.034
      Issue No: Vol. 72 (2017)
       
  • Robust Kalman estimators for systems with multiplicative and
           uncertain-variance linearly correlated additive white noises
    • Authors: Wenqiang Liu; Xuemei Wang; Zili Deng
      Pages: 230 - 247
      Abstract: Publication date: January 2018
      Source:Aerospace Science and Technology, Volume 72
      Author(s): Wenqiang Liu, Xuemei Wang, Zili Deng
      For linear discrete-time stochastic systems with mixed uncertainties including multiplicative and uncertain-variance linearly correlated additive white noises, this paper addresses the problem of designing robust Kalman estimators. By the fictitious noise-based Lyapunov equation approach, the system under consideration is converted into one with only uncertain noise variances. Based on the worst-case system with conservative upper bounds of actual noise variances, the minimax robust time-varying Kalman estimators (predictor, filter, and smoother) are presented in a unified framework. Their robustness is proved in the sense that their actual estimation error variances are guaranteed to have the corresponding minimal upper bounds for all admissible uncertainties. The corresponding robust steady-state Kalman estimators are also presented. An innovation test rule and a search technique of selecting the less-conservative upper bounds of actual noise variances are presented, by which the two classes of guaranteed robust accuracy Kalman estimators are presented. One class is robust Kalman estimators with improved robust accuracy, the other class is ones with the prescribed robust accuracy index. Three modes of convergence in a realization among the time-varying and steady-state robust Kalman estimators for the time-varying and time-invariant systems are presented and proved by the dynamic error system analysis (DESA) method. Two simulation examples applied to autoregressive (AR) signal processing and uninterruptible power system (UPS) show the effectiveness of the proposed results.

      PubDate: 2017-12-12T17:56:50Z
      DOI: 10.1016/j.ast.2017.11.008
      Issue No: Vol. 72 (2017)
       
  • Stability analysis of a multirotor vehicle hovering condition
    • Authors: Emanuele L. de Angelis
      Pages: 248 - 255
      Abstract: Publication date: January 2018
      Source:Aerospace Science and Technology, Volume 72
      Author(s): Emanuele L. de Angelis
      This paper presents a unified framework for addressing the stability analysis of the hovering condition for a multirotor vehicle. By linearization about a trim condition, a decoupled model made of four dynamic modes is derived. A set of stability derivatives is obtained and the effect on natural dynamic stability of design parameters such as arm dihedral and rotor tilt angles is analyzed. A numerical test case is finally discussed in support of the proposed approach.

      PubDate: 2017-12-12T17:56:50Z
      DOI: 10.1016/j.ast.2017.11.017
      Issue No: Vol. 72 (2017)
       
  • Database self-expansion based on artificial neural network: An approach in
           aircraft design
    • Authors: Shuyue Wang; Gang Sun Wanchun Chen Yongjian Zhong
      Abstract: Publication date: January 2018
      Source:Aerospace Science and Technology, Volume 72
      Author(s): Shuyue Wang, Gang Sun, Wanchun Chen, Yongjian Zhong
      Aircraft design today requires large amount of CFD calculation. For example when Natural Laminar Flow technique is applied to reduce aircraft skin friction drag by extending laminar length over surface, flowfield calculation related with airfoil laminar transition is computationally intense. Situations like this make iterative trial-and-error approach very inefficient. In order to improve this, this paper aims to exploit airfoil database of geometry and aerodynamic performance (from accumulated experiment and CFD calculation results) based on Artificial Neural Network to develop the approach of database self-expansion. It can generate airfoils with better aerodynamic performance from original database, so that the new airfoils can be applied to improve local aerodynamic performance of aircraft. The motive of the approach is to utilize the resource of accumulated optimization products in order to aid aircraft design. In this paper, we will discuss its application in laminar length extension over the surface of nacelle and wing. Geometry description in preparation of database establishment, configuration of network training, and workflow will be described in the paper.

      PubDate: 2017-11-11T08:45:18Z
       
  • Attitude acquisition from an arbitrary tumbling state using two skewed
           reaction wheels
    • Authors: H.Sh. Ousaloo
      Abstract: Publication date: Available online 3 November 2017
      Source:Aerospace Science and Technology
      Author(s): H.Sh. Ousaloo
      A novel technique has been designed that creates rapid nutation damping and accurate spin rate control for a spacecraft with arbitrary inertia ratio. In this approach the satellite incorporates two symmetrically inclined reaction wheels in a V configuration and stabilization is achieved by simultaneously controlling the angular velocity of the satellite and the wheels. The method furnishes gyroscopic stiffness and steers interchange of momentum between the wheels and the satellite main body. A Monte Carlo type approach is used to verify stability and it is shown that the controller provides automatically logical recovery of the desired spin for any initial state and inertia ratio. Moreover, results of single wheel simulations demonstrate the efficacy of the proposed concept.

      PubDate: 2017-11-05T08:34:20Z
      DOI: 10.1016/j.ast.2017.10.040
       
  • Ground effects on the stability of separated flow around a NACA 4415
           airfoil at low Reynolds numbers
    • Authors: Wei He; Peng Yu; Larry K.B. Li
      Abstract: Publication date: Available online 3 November 2017
      Source:Aerospace Science and Technology
      Author(s): Wei He, Peng Yu, Larry K.B. Li
      We perform a linear BiGlobal modal stability analysis on the separated flow around a NACA 4415 airfoil at low Reynolds numbers ( R e = 300 –1000) and a high angle of attack ( α = 20 ° ), with a focus on the effect of the airfoil's proximity to two different types of ground: a stationary ground and a moving ground. The results show that the most dominant perturbation is a Kelvin–Helmholtz mode, which gives rise to a supercritical Hopf bifurcation to a global mode, leading to large-scale vortex shedding at a periodic limit cycle. As the airfoil approaches the ground, this mode can become more unstable or less unstable, depending on the specific type of ground: introducing a stationary ground to an otherwise groundless system is destabilizing but introducing a moving ground is stabilizing, although both effects weaken with increasing Re. By performing a Floquet analysis, we find that short-wavelength secondary instabilities are damped by a moving ground but are amplified by a stationary ground. By contrast, long-wavelength secondary instabilities are relatively insensitive to ground type. This numerical–theoretical study shows that the ground can have an elaborate influence on the primary and secondary instabilities of the separated flow around an airfoil at low Re. These findings could be useful for the design of micro aerial vehicles and for improving our understanding of natural flyers such as insects and birds.

      PubDate: 2017-11-05T08:34:20Z
      DOI: 10.1016/j.ast.2017.10.039
       
  • Anti-disturbance fault tolerant initial alignment for inertial navigation
           system subjected to multiple disturbances
    • Authors: Songyin Cao; Lei Guo; Wenhua Chen
      Abstract: Publication date: Available online 3 November 2017
      Source:Aerospace Science and Technology
      Author(s): Songyin Cao, Lei Guo, Wenhua Chen
      Modeling error, stochastic error of inertial sensor, measurement noise and environmental disturbance affect the accuracy of an inertial navigation system (INS). In addition, some unpredictable factors, such as system fault, directly affect the reliability of INSs. This paper proposes a new anti-disturbance fault tolerant alignment approach for a class of INSs subjected to multiple disturbances and system faults. Based on modeling and error analysis, stochastic error of inertial sensor, measurement noise, modeling error and environmental disturbance are formulated into different types of disturbances described by a Markov stochastic process, Gaussian noise and a norm-bounded variable, respectively. In order to improve the accuracy and reliability of an INS, an anti-disturbance fault tolerant filter is designed. Then, a mixed dissipative/guarantee cost performance is applied to attenuate the norm-bounded disturbance and to optimize the estimation error. Slack variables and dissipativeness are introduced to reduce the conservatism of the proposed approach. Finally, compared with the unscented Kalman filter (UKF), simulation results for self-alignment of an INS are provided based on experimental data. It can be shown that the proposed method has an enhanced disturbance rejection and attenuation performance with high reliability.

      PubDate: 2017-11-05T08:34:20Z
      DOI: 10.1016/j.ast.2017.10.041
       
 
 
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