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Publisher: Elsevier   (Total: 3043 journals)

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Showing 1 - 200 of 3043 Journals sorted alphabetically
AASRI Procedia     Open Access   (Followers: 15)
Academic Pediatrics     Hybrid Journal   (Followers: 22, SJR: 1.402, h-index: 51)
Academic Radiology     Hybrid Journal   (Followers: 21, SJR: 1.008, h-index: 75)
Accident Analysis & Prevention     Partially Free   (Followers: 84, SJR: 1.109, h-index: 94)
Accounting Forum     Hybrid Journal   (Followers: 25, SJR: 0.612, h-index: 27)
Accounting, Organizations and Society     Hybrid Journal   (Followers: 30, SJR: 2.515, h-index: 90)
Achievements in the Life Sciences     Open Access   (Followers: 4)
Acta Anaesthesiologica Taiwanica     Open Access   (Followers: 5, SJR: 0.338, h-index: 19)
Acta Astronautica     Hybrid Journal   (Followers: 352, SJR: 0.726, h-index: 43)
Acta Automatica Sinica     Full-text available via subscription   (Followers: 3)
Acta Biomaterialia     Hybrid Journal   (Followers: 25, SJR: 2.02, h-index: 104)
Acta Colombiana de Cuidado Intensivo     Full-text available via subscription   (Followers: 1)
Acta de Investigación Psicológica     Open Access   (Followers: 2)
Acta Ecologica Sinica     Open Access   (Followers: 8, SJR: 0.172, h-index: 29)
Acta Haematologica Polonica     Free   (SJR: 0.123, h-index: 8)
Acta Histochemica     Hybrid Journal   (Followers: 3, SJR: 0.604, h-index: 38)
Acta Materialia     Hybrid Journal   (Followers: 235, SJR: 3.683, h-index: 202)
Acta Mathematica Scientia     Full-text available via subscription   (Followers: 5, SJR: 0.615, h-index: 21)
Acta Mechanica Solida Sinica     Full-text available via subscription   (Followers: 9, SJR: 0.442, h-index: 21)
Acta Oecologica     Hybrid Journal   (Followers: 10, SJR: 0.915, h-index: 53)
Acta Otorrinolaringologica (English Edition)     Full-text available via subscription   (Followers: 1)
Acta Otorrinolaringológica Española     Full-text available via subscription   (Followers: 3, SJR: 0.311, h-index: 16)
Acta Pharmaceutica Sinica B     Open Access   (Followers: 2)
Acta Poética     Open Access   (Followers: 4)
Acta Psychologica     Hybrid Journal   (Followers: 23, SJR: 1.365, h-index: 73)
Acta Sociológica     Open Access  
Acta Tropica     Hybrid Journal   (Followers: 6, SJR: 1.059, h-index: 77)
Acta Urológica Portuguesa     Open Access  
Actas Dermo-Sifiliograficas     Full-text available via subscription   (Followers: 4)
Actas Dermo-Sifiliográficas (English Edition)     Full-text available via subscription   (Followers: 3)
Actas Urológicas Españolas     Full-text available via subscription   (Followers: 4, SJR: 0.383, h-index: 19)
Actas Urológicas Españolas (English Edition)     Full-text available via subscription   (Followers: 2)
Actualites Pharmaceutiques     Full-text available via subscription   (Followers: 5, SJR: 0.141, h-index: 3)
Actualites Pharmaceutiques Hospitalieres     Full-text available via subscription   (Followers: 4, SJR: 0.112, h-index: 2)
Acupuncture and Related Therapies     Hybrid Journal   (Followers: 4)
Acute Pain     Full-text available via subscription   (Followers: 13)
Ad Hoc Networks     Hybrid Journal   (Followers: 11, SJR: 0.967, h-index: 57)
Addictive Behaviors     Hybrid Journal   (Followers: 15, SJR: 1.514, h-index: 92)
Addictive Behaviors Reports     Open Access   (Followers: 5)
Additive Manufacturing     Hybrid Journal   (Followers: 7, SJR: 1.039, h-index: 5)
Additives for Polymers     Full-text available via subscription   (Followers: 21)
Advanced Drug Delivery Reviews     Hybrid Journal   (Followers: 135, SJR: 5.2, h-index: 222)
Advanced Engineering Informatics     Hybrid Journal   (Followers: 11, SJR: 1.265, h-index: 53)
Advanced Powder Technology     Hybrid Journal   (Followers: 17, SJR: 0.739, h-index: 33)
Advances in Accounting     Hybrid Journal   (Followers: 9, SJR: 0.299, h-index: 15)
Advances in Agronomy     Full-text available via subscription   (Followers: 15, SJR: 2.071, h-index: 82)
Advances in Anesthesia     Full-text available via subscription   (Followers: 25, SJR: 0.169, h-index: 4)
Advances in Antiviral Drug Design     Full-text available via subscription   (Followers: 3)
Advances in Applied Mathematics     Full-text available via subscription   (Followers: 6, SJR: 1.054, h-index: 35)
Advances in Applied Mechanics     Full-text available via subscription   (Followers: 11, SJR: 0.801, h-index: 26)
Advances in Applied Microbiology     Full-text available via subscription   (Followers: 22, SJR: 1.286, h-index: 49)
Advances In Atomic, Molecular, and Optical Physics     Full-text available via subscription   (Followers: 16, SJR: 3.31, h-index: 42)
Advances in Biological Regulation     Hybrid Journal   (Followers: 4, SJR: 2.277, h-index: 43)
Advances in Botanical Research     Full-text available via subscription   (Followers: 3, SJR: 0.619, h-index: 48)
Advances in Cancer Research     Full-text available via subscription   (Followers: 25, SJR: 2.215, h-index: 78)
Advances in Carbohydrate Chemistry and Biochemistry     Full-text available via subscription   (Followers: 9, SJR: 0.9, h-index: 30)
Advances in Catalysis     Full-text available via subscription   (Followers: 5, SJR: 2.139, h-index: 42)
Advances in Cellular and Molecular Biology of Membranes and Organelles     Full-text available via subscription   (Followers: 12)
Advances in Chemical Engineering     Full-text available via subscription   (Followers: 26, SJR: 0.183, h-index: 23)
Advances in Child Development and Behavior     Full-text available via subscription   (Followers: 10, SJR: 0.665, h-index: 29)
Advances in Chronic Kidney Disease     Full-text available via subscription   (Followers: 9, SJR: 1.268, h-index: 45)
Advances in Clinical Chemistry     Full-text available via subscription   (Followers: 29, SJR: 0.938, h-index: 33)
Advances in Colloid and Interface Science     Full-text available via subscription   (Followers: 18, SJR: 2.314, h-index: 130)
Advances in Computers     Full-text available via subscription   (Followers: 16, SJR: 0.223, h-index: 22)
Advances in Dermatology     Full-text available via subscription   (Followers: 12)
Advances in Developmental Biology     Full-text available via subscription   (Followers: 11)
Advances in Digestive Medicine     Open Access   (Followers: 6)
Advances in DNA Sequence-Specific Agents     Full-text available via subscription   (Followers: 5)
Advances in Drug Research     Full-text available via subscription   (Followers: 22)
Advances in Ecological Research     Full-text available via subscription   (Followers: 41, SJR: 3.25, h-index: 43)
Advances in Engineering Software     Hybrid Journal   (Followers: 25, SJR: 0.486, h-index: 10)
Advances in Experimental Biology     Full-text available via subscription   (Followers: 7)
Advances in Experimental Social Psychology     Full-text available via subscription   (Followers: 41, SJR: 5.465, h-index: 64)
Advances in Exploration Geophysics     Full-text available via subscription   (Followers: 3)
Advances in Food and Nutrition Research     Full-text available via subscription   (Followers: 50, SJR: 0.674, h-index: 38)
Advances in Fuel Cells     Full-text available via subscription   (Followers: 16)
Advances in Genetics     Full-text available via subscription   (Followers: 15, SJR: 2.558, h-index: 54)
Advances in Genome Biology     Full-text available via subscription   (Followers: 11)
Advances in Geophysics     Full-text available via subscription   (Followers: 6, SJR: 2.325, h-index: 20)
Advances in Heat Transfer     Full-text available via subscription   (Followers: 22, SJR: 0.906, h-index: 24)
Advances in Heterocyclic Chemistry     Full-text available via subscription   (Followers: 9, SJR: 0.497, h-index: 31)
Advances in Imaging and Electron Physics     Full-text available via subscription   (Followers: 2, SJR: 0.396, h-index: 27)
Advances in Immunology     Full-text available via subscription   (Followers: 35, SJR: 4.152, h-index: 85)
Advances in Inorganic Chemistry     Full-text available via subscription   (Followers: 9, SJR: 1.132, h-index: 42)
Advances in Insect Physiology     Full-text available via subscription   (Followers: 3, SJR: 1.274, h-index: 27)
Advances in Integrative Medicine     Hybrid Journal   (Followers: 6)
Advances in Life Course Research     Hybrid Journal   (Followers: 8, SJR: 0.764, h-index: 15)
Advances in Lipobiology     Full-text available via subscription   (Followers: 2)
Advances in Magnetic and Optical Resonance     Full-text available via subscription   (Followers: 9)
Advances in Marine Biology     Full-text available via subscription   (Followers: 16, SJR: 1.645, h-index: 45)
Advances in Mathematics     Full-text available via subscription   (Followers: 10, SJR: 3.261, h-index: 65)
Advances in Medical Sciences     Hybrid Journal   (Followers: 6, SJR: 0.489, h-index: 25)
Advances in Medicinal Chemistry     Full-text available via subscription   (Followers: 5)
Advances in Microbial Physiology     Full-text available via subscription   (Followers: 4, SJR: 1.44, h-index: 51)
Advances in Molecular and Cell Biology     Full-text available via subscription   (Followers: 22)
Advances in Molecular and Cellular Endocrinology     Full-text available via subscription   (Followers: 10)
Advances in Molecular Toxicology     Full-text available via subscription   (Followers: 7, SJR: 0.324, h-index: 8)
Advances in Nanoporous Materials     Full-text available via subscription   (Followers: 4)
Advances in Oncobiology     Full-text available via subscription   (Followers: 3)
Advances in Organometallic Chemistry     Full-text available via subscription   (Followers: 15, SJR: 2.885, h-index: 45)
Advances in Parallel Computing     Full-text available via subscription   (Followers: 7, SJR: 0.148, h-index: 11)
Advances in Parasitology     Full-text available via subscription   (Followers: 7, SJR: 2.37, h-index: 73)
Advances in Pediatrics     Full-text available via subscription   (Followers: 24, SJR: 0.4, h-index: 28)
Advances in Pharmaceutical Sciences     Full-text available via subscription   (Followers: 13)
Advances in Pharmacology     Full-text available via subscription   (Followers: 15, SJR: 1.718, h-index: 58)
Advances in Physical Organic Chemistry     Full-text available via subscription   (Followers: 8, SJR: 0.384, h-index: 26)
Advances in Phytomedicine     Full-text available via subscription  
Advances in Planar Lipid Bilayers and Liposomes     Full-text available via subscription   (Followers: 3, SJR: 0.248, h-index: 11)
Advances in Plant Biochemistry and Molecular Biology     Full-text available via subscription   (Followers: 8)
Advances in Plant Pathology     Full-text available via subscription   (Followers: 5)
Advances in Porous Media     Full-text available via subscription   (Followers: 4)
Advances in Protein Chemistry     Full-text available via subscription   (Followers: 17)
Advances in Protein Chemistry and Structural Biology     Full-text available via subscription   (Followers: 20, SJR: 1.5, h-index: 62)
Advances in Psychology     Full-text available via subscription   (Followers: 61)
Advances in Quantum Chemistry     Full-text available via subscription   (Followers: 5, SJR: 0.478, h-index: 32)
Advances in Radiation Oncology     Open Access  
Advances in Small Animal Medicine and Surgery     Hybrid Journal   (Followers: 3, SJR: 0.1, h-index: 2)
Advances in Space Research     Full-text available via subscription   (Followers: 353, SJR: 0.606, h-index: 65)
Advances in Structural Biology     Full-text available via subscription   (Followers: 8)
Advances in Surgery     Full-text available via subscription   (Followers: 7, SJR: 0.823, h-index: 27)
Advances in the Study of Behavior     Full-text available via subscription   (Followers: 30, SJR: 1.321, h-index: 56)
Advances in Veterinary Medicine     Full-text available via subscription   (Followers: 17)
Advances in Veterinary Science and Comparative Medicine     Full-text available via subscription   (Followers: 13)
Advances in Virus Research     Full-text available via subscription   (Followers: 5, SJR: 1.878, h-index: 68)
Advances in Water Resources     Hybrid Journal   (Followers: 43, SJR: 2.408, h-index: 94)
Aeolian Research     Hybrid Journal   (Followers: 5, SJR: 0.973, h-index: 22)
Aerospace Science and Technology     Hybrid Journal   (Followers: 325, SJR: 0.816, h-index: 49)
AEU - Intl. J. of Electronics and Communications     Hybrid Journal   (Followers: 8, SJR: 0.318, h-index: 36)
African J. of Emergency Medicine     Open Access   (Followers: 5, SJR: 0.344, h-index: 6)
Ageing Research Reviews     Hybrid Journal   (Followers: 8, SJR: 3.289, h-index: 78)
Aggression and Violent Behavior     Hybrid Journal   (Followers: 406, SJR: 1.385, h-index: 72)
Agri Gene     Hybrid Journal  
Agricultural and Forest Meteorology     Hybrid Journal   (Followers: 16, SJR: 2.18, h-index: 116)
Agricultural Systems     Hybrid Journal   (Followers: 30, SJR: 1.275, h-index: 74)
Agricultural Water Management     Hybrid Journal   (Followers: 39, SJR: 1.546, h-index: 79)
Agriculture and Agricultural Science Procedia     Open Access  
Agriculture and Natural Resources     Open Access   (Followers: 1)
Agriculture, Ecosystems & Environment     Hybrid Journal   (Followers: 54, SJR: 1.879, h-index: 120)
Ain Shams Engineering J.     Open Access   (Followers: 5, SJR: 0.434, h-index: 14)
Air Medical J.     Hybrid Journal   (Followers: 5, SJR: 0.234, h-index: 18)
AKCE Intl. J. of Graphs and Combinatorics     Open Access   (SJR: 0.285, h-index: 3)
Alcohol     Hybrid Journal   (Followers: 11, SJR: 0.922, h-index: 66)
Alcoholism and Drug Addiction     Open Access   (Followers: 8)
Alergologia Polska : Polish J. of Allergology     Full-text available via subscription   (Followers: 1)
Alexandria Engineering J.     Open Access   (Followers: 1, SJR: 0.436, h-index: 12)
Alexandria J. of Medicine     Open Access  
Algal Research     Partially Free   (Followers: 8, SJR: 2.05, h-index: 20)
Alkaloids: Chemical and Biological Perspectives     Full-text available via subscription   (Followers: 3)
Allergologia et Immunopathologia     Full-text available via subscription   (Followers: 1, SJR: 0.46, h-index: 29)
Allergology Intl.     Open Access   (Followers: 4, SJR: 0.776, h-index: 35)
Alpha Omegan     Full-text available via subscription   (SJR: 0.121, h-index: 9)
ALTER - European J. of Disability Research / Revue Européenne de Recherche sur le Handicap     Full-text available via subscription   (Followers: 8, SJR: 0.158, h-index: 9)
Alzheimer's & Dementia     Hybrid Journal   (Followers: 48, SJR: 4.289, h-index: 64)
Alzheimer's & Dementia: Diagnosis, Assessment & Disease Monitoring     Open Access   (Followers: 6)
Alzheimer's & Dementia: Translational Research & Clinical Interventions     Open Access   (Followers: 5)
American Heart J.     Hybrid Journal   (Followers: 49, SJR: 3.157, h-index: 153)
American J. of Cardiology     Hybrid Journal   (Followers: 47, SJR: 2.063, h-index: 186)
American J. of Emergency Medicine     Hybrid Journal   (Followers: 39, SJR: 0.574, h-index: 65)
American J. of Geriatric Pharmacotherapy     Full-text available via subscription   (Followers: 8, SJR: 1.091, h-index: 45)
American J. of Geriatric Psychiatry     Hybrid Journal   (Followers: 15, SJR: 1.653, h-index: 93)
American J. of Human Genetics     Hybrid Journal   (Followers: 31, SJR: 8.769, h-index: 256)
American J. of Infection Control     Hybrid Journal   (Followers: 25, SJR: 1.259, h-index: 81)
American J. of Kidney Diseases     Hybrid Journal   (Followers: 32, SJR: 2.313, h-index: 172)
American J. of Medicine     Hybrid Journal   (Followers: 45, SJR: 2.023, h-index: 189)
American J. of Medicine Supplements     Full-text available via subscription   (Followers: 3)
American J. of Obstetrics and Gynecology     Hybrid Journal   (Followers: 233, SJR: 2.255, h-index: 171)
American J. of Ophthalmology     Hybrid Journal   (Followers: 58, SJR: 2.803, h-index: 148)
American J. of Ophthalmology Case Reports     Open Access   (Followers: 5)
American J. of Orthodontics and Dentofacial Orthopedics     Full-text available via subscription   (Followers: 6, SJR: 1.249, h-index: 88)
American J. of Otolaryngology     Hybrid Journal   (Followers: 25, SJR: 0.59, h-index: 45)
American J. of Pathology     Hybrid Journal   (Followers: 26, SJR: 2.653, h-index: 228)
American J. of Preventive Medicine     Hybrid Journal   (Followers: 22, SJR: 2.764, h-index: 154)
American J. of Surgery     Hybrid Journal   (Followers: 34, SJR: 1.286, h-index: 125)
American J. of the Medical Sciences     Hybrid Journal   (Followers: 12, SJR: 0.653, h-index: 70)
Ampersand : An Intl. J. of General and Applied Linguistics     Open Access   (Followers: 5)
Anaerobe     Hybrid Journal   (Followers: 4, SJR: 1.066, h-index: 51)
Anaesthesia & Intensive Care Medicine     Full-text available via subscription   (Followers: 57, SJR: 0.124, h-index: 9)
Anaesthesia Critical Care & Pain Medicine     Full-text available via subscription   (Followers: 11)
Anales de Cirugia Vascular     Full-text available via subscription  
Anales de Pediatría     Full-text available via subscription   (Followers: 2, SJR: 0.209, h-index: 27)
Anales de Pediatría (English Edition)     Full-text available via subscription  
Anales de Pediatría Continuada     Full-text available via subscription   (SJR: 0.104, h-index: 3)
Analytic Methods in Accident Research     Hybrid Journal   (Followers: 4, SJR: 2.577, h-index: 7)
Analytica Chimica Acta     Hybrid Journal   (Followers: 37, SJR: 1.548, h-index: 152)
Analytical Biochemistry     Hybrid Journal   (Followers: 167, SJR: 0.725, h-index: 154)
Analytical Chemistry Research     Open Access   (Followers: 8, SJR: 0.18, h-index: 2)
Analytical Spectroscopy Library     Full-text available via subscription   (Followers: 11)
Anesthésie & Réanimation     Full-text available via subscription   (Followers: 1)
Anesthesiology Clinics     Full-text available via subscription   (Followers: 22, SJR: 0.421, h-index: 40)
Angiología     Full-text available via subscription   (SJR: 0.124, h-index: 9)
Angiologia e Cirurgia Vascular     Open Access  
Animal Behaviour     Hybrid Journal   (Followers: 161, SJR: 1.907, h-index: 126)
Animal Feed Science and Technology     Hybrid Journal   (Followers: 5, SJR: 1.151, h-index: 83)
Animal Reproduction Science     Hybrid Journal   (Followers: 5, SJR: 0.711, h-index: 78)
Annales d'Endocrinologie     Full-text available via subscription   (Followers: 1, SJR: 0.394, h-index: 30)
Annales d'Urologie     Full-text available via subscription  
Annales de Cardiologie et d'Angéiologie     Full-text available via subscription   (SJR: 0.177, h-index: 13)
Annales de Chirurgie de la Main et du Membre Supérieur     Full-text available via subscription  
Annales de Chirurgie Plastique Esthétique     Full-text available via subscription   (Followers: 2, SJR: 0.354, h-index: 22)
Annales de Chirurgie Vasculaire     Full-text available via subscription   (Followers: 1)

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Journal Cover Aerospace Science and Technology
  [SJR: 0.816]   [H-I: 49]   [325 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1270-9638
   Published by Elsevier Homepage  [3043 journals]
  • A mixed probabilistic–geometric strategy for UAV optimum flight path
           identification based on bit-coded basic manoeuvres
    • Authors: Luciano Blasi; Simeone Barbato; Egidio D'Amato
      Pages: 1 - 11
      Abstract: Publication date: December 2017
      Source:Aerospace Science and Technology, Volume 71
      Author(s): Luciano Blasi, Simeone Barbato, Egidio D'Amato
      This paper presents a novel algorithm identifying optimal flight trajectories for Unmanned Aerial Vehicles compliant with environmental constraints. Such constraints are defined in terms of obstacles, fixed way-points and selected destination points. Optimality is evaluated taking the minimum path length as the specific objective function. The proposed path planning strategy is based on an original trajectory modelling coupled with a Particle Swarm optimizer (PSO). Flight paths starting from a specified point and ending at a selected destination point are divided into a finite number of segments made up of circular arcs and straight lines. In the proposed approach such a geometrical sequence is replaced with a finite sequence of binary-coded basic manoeuvres. This novel formulation allows to easily handle the manoeuvres sequence with a fixed number of integer variables taking advantage of PSO capability in handling discrete variables; moreover the use of mixed-type variables provides the optimization procedure a useful flexibility in the “decision making” modelling and operational scenarios definition as well. Specific geometric-based linear obstacle avoidance models have been implemented in addition to suitable penalty functions. The use of these models forces each path to be consistent with the environmental constraints favouring the identification of feasible trajectories with a reduced number of iterations and particles. The path planning model has been developed with particular care devoted to reduce computational effort as well as to improve algorithm capability in handling general-shaped obstacles both in 2-D and 3-D environments. Various applications have been performed in order to test the effectiveness of the proposed flight path generator. Applicability of the proposed optimization model also to vehicles with VTOL and hovering capabilities has been preliminarily assessed.

      PubDate: 2017-09-23T08:17:03Z
      DOI: 10.1016/j.ast.2017.09.007
      Issue No: Vol. 71 (2017)
       
  • Adaptive unscented Kalman filter based on maximum posterior and random
           weighting
    • Authors: Zhaohui Gao; Dejun Mu; Shesheng Gao; Yongmin Zhong; Chengfan Gu
      Pages: 12 - 24
      Abstract: Publication date: December 2017
      Source:Aerospace Science and Technology, Volume 71
      Author(s): Zhaohui Gao, Dejun Mu, Shesheng Gao, Yongmin Zhong, Chengfan Gu
      The unscented Kalman filter (UKF) is an effective technique of state estimation for nonlinear dynamic systems. However, its performance depends on prior knowledge on system noise. If the characteristics of system noise are unknown or inaccurate, the filtering solution may be biased or even divergent. This paper presents a new maximum posterior and random weighting based adaptive UKF (MRAUKF) by combining the concepts of maximum posterior and random weighting to overcome this limitation. The proposed MRAUKF computes noise statistics based on the maximum posterior principle, and subsequently adopts the random weighting concept to optimize the obtained maximum posterior estimations by online adjusting the weights on residuals. The maximum posterior and random weighting estimations of noise statistics are established to online estimate and adjust system noise statistics, leading to the improved filtering robustness. Simulation and experimental results demonstrate that the proposed MRAUKF outperforms the classical UKF and adaptive robust UKF in the presence of uncertain system noise statistics.

      PubDate: 2017-09-30T08:28:22Z
      DOI: 10.1016/j.ast.2017.08.020
      Issue No: Vol. 71 (2017)
       
  • On the utilisation of nonlinear plasticity models in military aircraft
           fatigue estimation: A preliminary comparison
    • Authors: Dylan Agius; Chris Wallbrink; Weiping Hu; Mladenko Kajtaz; Chun H. Wang; Kyriakos I. Kourousis
      Pages: 25 - 29
      Abstract: Publication date: December 2017
      Source:Aerospace Science and Technology, Volume 71
      Author(s): Dylan Agius, Chris Wallbrink, Weiping Hu, Mladenko Kajtaz, Chun H. Wang, Kyriakos I. Kourousis
      Strain-life methodologies are commonly employed for fatigue estimation in military aircraft structures. These methodologies rely on models describing the elastoplastic response of the material under cycling. Despite the numerous advanced plasticity models proposed and utilised in various engineering problems over the past decades, the Masing model remains a popular choice in fatigue analysis software, mainly due to its simplicity. However, in the case of military aircraft load spectra including scattered overloads the Masing model fails to represent adequately transient cyclic phenomena, such as mean stress relaxation and strain ratcheting. In this study, four well-known constitutive plasticity models have been selected as potential substitutes for the Masing model within a defence organisation in-house developed fatigue analysis software. These models assessed were the well-known Multicomponent Armstrong–Frederick Model (MAF) and three of its derivatives: MAF with threshold (MAFT), Ohno–Wang (OW) and MAF with Multiplier (MAFM). The models were calibrated with the use of existing experimental data, obtained from aircraft aluminium alloy tests. Optimisation of the parameters was performed through a genetic algorithm-based commercial software. The models were incorporated in the fatigue analysis software and their performance was evaluated statistically and compared against each other and with the Masing model for a series of different flight load spectra for a military aircraft. The results show that all four models have achieved a drastic improvement in fatigue analysis, with the MAFT model giving a slightly better performance.

      PubDate: 2017-09-30T08:28:22Z
      DOI: 10.1016/j.ast.2017.09.004
      Issue No: Vol. 71 (2017)
       
  • Comprehensive preliminary sizing/resizing method for a fixed wing –
           VTOL electric UAV
    • Authors: Maxim Tyan; Nhu Van Nguyen; Sangho Kim; Jae-Woo Lee
      Pages: 30 - 41
      Abstract: Publication date: December 2017
      Source:Aerospace Science and Technology, Volume 71
      Author(s): Maxim Tyan, Nhu Van Nguyen, Sangho Kim, Jae-Woo Lee
      A Fixed Wing (FW) aircraft with Vertical Takeoff and Landing (VTOL) is a new type of aircraft that inherits the hovering, VTOL, and maneuvering properties of multicopters and the power-efficient cruising of an FW aircraft. This paper presents a comprehensive method for FW-VTOL electric UAV sizing and resizing. The method uses newly developed integrated analysis that combines the VTOL propulsion sizing method with modified FW aircraft sizing theories. Performance requirements are specified as a set of functional relations. Several new empirical equations are derived using available data. The required battery capacity and total mass are determined from mission analysis that includes both VTOL and FW mission segments. The design is iteratively resized when the actual components of the propulsion system are selected. A case study of a 3.5-kg FW-VTOL electric UAV is presented in this research. The results of sizing and resizing are compared to parameters of the actual aircraft manufactured. Prediction of most parameters stays within a 10% error threshold.

      PubDate: 2017-09-30T08:28:22Z
      DOI: 10.1016/j.ast.2017.09.008
      Issue No: Vol. 71 (2017)
       
  • A design approach of wide-speed-range vehicles based on the cone-derived
           theory
    • Authors: Tian-tian Zhang; Zhen-guo Wang; Wei Huang; Shi-bin Li
      Pages: 42 - 51
      Abstract: Publication date: December 2017
      Source:Aerospace Science and Technology, Volume 71
      Author(s): Tian-tian Zhang, Zhen-guo Wang, Wei Huang, Shi-bin Li
      The hypersonic gliding vehicle is attracting an increasing attention because of its high lift-to-drag ratio and cruising velocity. This kind of vehicle may experience different airspaces as well as different speed environments. Based on the design theory of the cone-derived waverider, a novel design approach of the hypersonic gliding vehicle was proposed in this article, which is accommodated in a wide speed range. The parametric method employed in the ascender line design makes it possible to control the overall configuration of the vehicle, and there are four parameters chosen to describe the ascender line. The numerical approach has been employed to validate the property of this kind of HGV. By analyzing the pressure contour of the vehicles with different Mach numbers, we conclude that this kind of aircraft own good wave-ride properties in the designed speed range. Their aerodynamic performance makes a balance by comparing with the waveriders designed with the two ultimate speeds. Different design Mach number arrangements lead to different aerodynamic properties, and all of them seem to be suitable in the designed speed range. Therefore, this kind of vehicle is worth referring in the aircraft design. The simplified trajectory performance analysis is employed, and the vehicle is assumed to reentry with a given initial condition. With the angle of attack as well as the angle of slide is set to be zero. The CFD method obtained the aerodynamic coefficients of the vehicle at different speeds. The result shows a wavy trajectory with long range, which means that this kind of vehicle is suitable for long-distance transportation.

      PubDate: 2017-09-30T08:28:22Z
      DOI: 10.1016/j.ast.2017.09.010
      Issue No: Vol. 71 (2017)
       
  • Structural reliability sensitivity analysis based on classification of
           model output
    • Authors: Sinan Xiao; Zhenzhou Lu
      Pages: 52 - 61
      Abstract: Publication date: December 2017
      Source:Aerospace Science and Technology, Volume 71
      Author(s): Sinan Xiao, Zhenzhou Lu
      In structural reliability analysis, sensitivity analysis can be used to measure how the input variable influences the failure of structure. In this work, a new reliability sensitivity analysis method is proposed. In the proposed method, the model output is separated into two classes (failure domain and safe domain). The basic idea is that if the failure-conditional probability density function of input variable is significantly different from its unconditional probability density function, then the input variable is sensitive to the failure of structure. The proposed reliability sensitivity indices contain both individual sensitivity index and interaction sensitivity index. The individual sensitivity index can measure the individual effect of input variable on the failure of structure. The asymmetrical interaction sensitivity index can measure how one input variable influences the effect of another input variable on the failure of structure. Additionally, the meanings of the proposed reliability sensitivity indices are also interpreted explicitly, and a data-driven estimation method is also proposed to estimate the proposed reliability sensitivity indices. Finally, a numerical example and two engineering examples are presented to illustrate the rationality of the proposed sensitivity indices and the feasibility of the proposed estimation method.

      PubDate: 2017-09-30T08:28:22Z
      DOI: 10.1016/j.ast.2017.09.009
      Issue No: Vol. 71 (2017)
       
  • Finite-time formation control for multiple flight vehicles with accurate
           linearization model
    • Authors: Enjiao Zhao; Tao Chao; Songyan Wang; Ming Yang
      Pages: 90 - 98
      Abstract: Publication date: December 2017
      Source:Aerospace Science and Technology, Volume 71
      Author(s): Enjiao Zhao, Tao Chao, Songyan Wang, Ming Yang
      The finite-time leader–follower formation control problem of Multiple Flight Vehicle (MFV) system with accurate linearization model is considered. Herein, there is only one leader, the interaction topology among the followers is undirected, and the followers are reachable from the leader. Precise feedback linearization based on differential geometry theory is used to linearize the nonlinear motion model of the flight vehicle and the system model with follower track errors is formulated. A distributed formation control protocol based on finite-time control theory is proposed. With the designed control law, the MFV systems can achieve the desired formation in finite time, where the formation configurations can be specified in advance according to the task requirements. Meanwhile, the convergence analysis is proved and the protocol performance is discussed. Finally, simulation results further demonstrate the effectiveness of the proposed method.

      PubDate: 2017-09-30T08:28:22Z
      DOI: 10.1016/j.ast.2017.08.018
      Issue No: Vol. 71 (2017)
       
  • Study on the effects of ionization seeds on pulse detonation
           characteristics
    • Authors: Ling Lin; Chunsheng Weng; Qingzhang Chen; Hongyu Jiao
      Pages: 128 - 135
      Abstract: Publication date: December 2017
      Source:Aerospace Science and Technology, Volume 71
      Author(s): Ling Lin, Chunsheng Weng, Qingzhang Chen, Hongyu Jiao
      Ionization phenomenon is happened on the wave front due to the presence of high temperature and pressure in the detonation process. Plasma produced in the detonation process can be used as magnetohydrodynamic (MHD) generator or flow controlled by the external magnetic field. However, it is necessary to increase the ionization efficiency by adding metal ions with lower ionization potential owing to the limited amount of plasma produced by detonation. In this paper, a model of pulse detonation engine with ionization seeds was established. The Conservation Element and Solution Element (CE/SE) method was deduced to simulate the interaction between plasma and detonation process. The influence of ionization seed contents on the electrical conductivity and detonation characteristic parameters was analyzed, and the MHD control of detonation process was realized by adding the external electromagnetic field device. The results showed that it had a little influence on the detonation process but a great influence on the generation of detonation plasma by the addition of a certain amount of ionized seed. The ion mass fraction and electrical conductivity in the detonation tube were first increased and then decreased with the increase of ionization seed content, which reached the maximum at the ionization seed mass fraction of 0.05. The acceleration and deceleration process could be achieved by the MHD control.

      PubDate: 2017-09-30T08:28:22Z
      DOI: 10.1016/j.ast.2017.09.015
      Issue No: Vol. 71 (2017)
       
  • Dual-filter transfer alignment for airborne distributed POS based on PVAM
    • Authors: Zhaoxing Lu; Jiancheng Fang; Haojie Liu; Xiaolin Gong; Shicheng Wang
      Pages: 136 - 146
      Abstract: Publication date: December 2017
      Source:Aerospace Science and Technology, Volume 71
      Author(s): Zhaoxing Lu, Jiancheng Fang, Haojie Liu, Xiaolin Gong, Shicheng Wang
      Distributed array antenna synthetic aperture radar (SAR), flexible baseline interferometric SAR (InSAR) or integrated multi-task imaging sensors are the most attractive development directions of aerial survey and remote sensing system, and urgently demand a distributed Position and Orientation System (DPOS) to accurately measure multi-nodes time-spatial reference information. However, the traditional transfer alignment (TA) method can't meet the requirements of some high precision interferometric imaging task. To solve the problem, a dual-filter TA method based on position-velocity-attitude matching (PVAM) was proposed. Firstly, the TA method based on attitude matching (AM) is conducted in filter-1 to estimate the flexible angles and the derivatives. Then the TA method based on position-velocity matching (PVM) is conducted in filter-2, and the position and velocity measurements are compensated by the flexible angles and the derivatives estimated by filter-1. Finally, the strapdown solutions of slave IMU are corrected by the corrections from both filter-1 and filter-2. A semi-physical simulation based on airborne DPOS flight experiment has been conducted, verifying that the baseline error has been reduced from 0.0240 m to 0.0083 m and the computation time has been decrease by 3.41%.

      PubDate: 2017-09-30T08:28:22Z
      DOI: 10.1016/j.ast.2017.09.016
      Issue No: Vol. 71 (2017)
       
  • Coverage-based cooperative guidance strategy against highly maneuvering
           target
    • Authors: Wenshan Su; Kebo Li; Lei Chen
      Pages: 147 - 155
      Abstract: Publication date: December 2017
      Source:Aerospace Science and Technology, Volume 71
      Author(s): Wenshan Su, Kebo Li, Lei Chen
      Considering highly maneuvering target, a novel cooperative guidance strategy, which aims to make multiple missiles' joint reachable sets cover the target evasion region, is proposed. The assumed engagement scenario is that multiple missiles separate with each other at the beginning of homing phase and then cooperatively intercept the highly maneuvering target which cannot be intercepted by single missile due to insufficient maneuverability. Firstly, for biasing the reachable sets of different missiles to cover different subintervals of target maneuvering range as expected, a biased proportional navigation guidance law (BPN) is designed by introducing the virtual aiming point. Secondly, for the missile-team without communication capability, the minimum relative maneuverability superiority and minimum team size for covering the whole target maneuvering range are derived based on the BPN respectively, and one open-loop cooperative guidance strategy is proposed with an acceptable assumption about the handover errors of midcourse guidance. While for the missile-team with communication capability, a novel coordinating variable is designed and the corresponding closed-loop guidance strategy is proposed. Numerical simulations with different target maneuver modes are presented to verify the guidance performance of the proposed cooperative guidance strategy.

      PubDate: 2017-10-08T08:50:02Z
      DOI: 10.1016/j.ast.2017.09.021
      Issue No: Vol. 71 (2017)
       
  • Swing principle in tether-assisted return mission from an elliptical orbit
    • Authors: Vladimir S. Aslanov; Alexander S. Ledkov
      Pages: 156 - 162
      Abstract: Publication date: December 2017
      Source:Aerospace Science and Technology, Volume 71
      Author(s): Vladimir S. Aslanov, Alexander S. Ledkov
      The problem of a tether-assisted payload return from an elliptical orbit is considered in this study. In contrast to the existing works devoted to this issue, the article deals with a tether length control that provides a transfer of the payload into a descent trajectory from the tether rotation mode. Application of the swing principle for the tether control is investigated. The simplified mathematical model of the space tethered system is developed. It is shown that the stable limit cycle could exist under the considered control. The approximate analytical solution for this cycle is obtained. The stability of this solution is studied by the Lyapunov's theorems. The optimal control, which provides transfer of the payload into the descent trajectory with minimum perigee radius, is found as a result of the simulation series. It is shown that the tether should occur several turns before the payload separation. For example, in the YES-2 experiment, it is demonstrated that proposed control makes it possible to perform a payload return using a tether of considerably shorter length. The main conclusion of the paper is that the proposed scheme of the payload deorbit is more effective than the classical static or dynamic tether deployment schemes.

      PubDate: 2017-10-08T08:50:02Z
      DOI: 10.1016/j.ast.2017.09.006
      Issue No: Vol. 71 (2017)
       
  • Optimization of slot geometry in shock wave boundary layer interaction
           phenomenon by using CFD–ANN–GA cycle
    • Authors: M. Karbasizadeh; A.R. Babaei; M. Bazazzadeh; M.D. Menshadi
      Pages: 163 - 171
      Abstract: Publication date: December 2017
      Source:Aerospace Science and Technology, Volume 71
      Author(s): M. Karbasizadeh, A.R. Babaei, M. Bazazzadeh, M.D. Menshadi
      Slot is one of the measures to control the Shock Wave–Boundary Layer Interaction (SBLI) used to avoid strong interference of shock waves with the boundary layer in supersonic flows. In this control measure, the Height of Triple Point (HTP) of λ shock significantly increases, compared to the one without controller, and cause a decline in shock power and pressure drops rate. In this paper, the main focus is on optimization of slot geometry as an influential parameter on the structure of the shock and flow characteristics by using Genetic Algorithm (GA). The averaged implicit Navier–Stokes equations and two equation standard k–ω turbulence models for the numerical simulation of the flow field have been used. The optimization problem is formulated in term of one objective function, namely, height of triple point maximization. Artificial neural network with two hidden layers has been used to achieve objective function based on the numerical simulation of the flow field data base. Root Mean Square Error (RMSE) was calculated for comparison and selecting the best algorithm in sequential steps. In order to simulate and compare the results with data obtained from experimental tests, the Cambridge University's wind tunnel tests and geometry have been used as the base design. The study demonstrates that, the HTP for optimized slot geometry is about 7.6 percentages more than base design.

      PubDate: 2017-10-08T08:50:02Z
      DOI: 10.1016/j.ast.2017.09.019
      Issue No: Vol. 71 (2017)
       
  • Developing an optimal layout design of a satellite system by considering
           natural frequency and attitude control constraints
    • Authors: Mahdi Fakoor; Parviz Mohammad Zadeh; Homa Momeni Eskandari
      Pages: 172 - 188
      Abstract: Publication date: December 2017
      Source:Aerospace Science and Technology, Volume 71
      Author(s): Mahdi Fakoor, Parviz Mohammad Zadeh, Homa Momeni Eskandari
      In recent years, there has been a growing research interest in layout design optimization of satellite systems. The layout design optimization of a satellite system is a complex process having a large number of design variables and constraints. This paper presents a hybrid optimization algorithm, which globally explores the design search space using Particle Swarm Optimization (PSO) and gradient-based Sequential Quadratic Programming (SQP) to rapidly locate optimum design point. The majority of the previous research works mainly focused on finding reasonable placement of components in satellite layout design, with some specific requirements, which are essential for the satellite stability, control and performance such as attitude control, non-interference and overlap constraints. In this study, additional requirements such as structural stiffness and natural frequency constraints are also considered. The proposed approach is employed on a simplified international global communication satellite. The obtained results indicate that the consideration of natural frequency and attitude control constraints in the configuration layout design of a satellite system can significantly improve the stability and control of the satellite and thus frequency coupling between satellite and launcher can be prevented. In addition, the results indicate that the proposed method provides an effective way of solving layout design optimization problem of satellite systems.

      PubDate: 2017-10-08T08:50:02Z
      DOI: 10.1016/j.ast.2017.09.012
      Issue No: Vol. 71 (2017)
       
  • Design and analysis on three-dimensional scramjet nozzles with shape
           transition
    • Authors: Zheng Lv; Jinglei Xu; Jianwei Mo
      Pages: 189 - 200
      Abstract: Publication date: December 2017
      Source:Aerospace Science and Technology, Volume 71
      Author(s): Zheng Lv, Jinglei Xu, Jianwei Mo
      A trimming method to optimize the configuration of a three-dimensional asymmetric nozzle with shape transition, which aims to obtain good aerodynamic performance and to save weight at the same time, is presented in this paper. Then the effects of the entry shape on the performance of the three-dimensional nozzle are investigated. The streamline tracing involved in an axisymmetric flowfield with optimal thrust is employed to obtain the inviscid contour of the three-dimensional nozzle with shape transition, and the reference temperature method is applied to correct the thickness of the boundary layer. The performance of the designed nozzle is obtained by using computational fluid dynamics. The calculated results show that the trimmed nozzle gains increases in the lift and pitching moment by 427.00% and 10.80%, respectively, with only a 0.76% decrease in the axial thrust coefficient, while the weight can be reduced by as much as 37.51%. For the nozzles with elliptical entrances, as the axial ratio ranges from 1.0 to 2.0, the axial thrust coefficient is increased by 5.38%, while the lift is decreased by 67.74%. When considering the nozzles with rectangular entrances, as the aspect ratio ranges 1.0 to 2.0, the axial thrust coefficient is increased by 3.58%, while the lift and pitching moment are decreased by 82.09% and 16.43%, respectively. Most of the axial thrust is produced on the upper-wall and side-walls in all nozzles, and the contribution of the expansion flow along the side-walls on the thrust generation is pronounced in the nozzle with a relatively smaller entry ratio. However, the majority of the lift and pitching moment are generated on the upper-wall and lower-wall. Besides, the viscosity loss and weight can be reduced by applying the elliptical cross-section in the propulsion system.

      PubDate: 2017-10-08T08:50:02Z
      DOI: 10.1016/j.ast.2017.09.025
      Issue No: Vol. 71 (2017)
       
  • An approach to estimate aircraft touchdown attitudes and control inputs
    • Authors: P. Wu; M. Voskuijl; L.L.M. Veldhuis
      Pages: 201 - 213
      Abstract: Publication date: December 2017
      Source:Aerospace Science and Technology, Volume 71
      Author(s): P. Wu, M. Voskuijl, L.L.M. Veldhuis
      More strict aircraft emission criteria are proposed by the European Union and the United States. Moreover, the rapid development of the global aviation transportation market also asks for more fuel-efficient aircraft. An innovative assisted takeoff and landing technology is proposed in the EU FP-7 project GABRIEL with the aim to improve fuel-efficiency of commercial aircraft. The technology is based on the removal of the conventional landing gears and the introduction of a ground based landing system. This result in a significant reduction of the structural weight and thereby aircraft performance and fuel efficiency are improved. Furthermore, both airport noise and congestion can be decreased as the aircraft can reach a higher take-off speed without the need for longer runways. The ground based system has a yaw degree of freedom and therefore, the conventional de-crab maneuver for crosswind landings can be avoided. As a consequence, the possible touchdown attitudes and control inputs will be different from those seen in conventional landing. The flight attitudes and control inputs of aircraft during touchdown can significantly influence the landing impacts. Generally, these parameters are obtained from flight test or empirical data and they are crucial for landing gear design. However, the use of empirical data is not possible for new innovative designs such as the GABRIEL system. This paper proposes a solution to estimate all possible aircraft touchdown attitudes and control inputs based on flight dynamics simulations and Monte Carlo evaluation. Turbulence is accounted for based on the von Karman turbulence model. The GABRIEL system is used as a test case and 100 sets of stochastic turbulence are implemented. The resulting flight attitudes and control inputs are presented for different control strategies and compared to the results of landing simulations with a conventional landing gear.

      PubDate: 2017-10-08T08:50:02Z
      DOI: 10.1016/j.ast.2017.09.023
      Issue No: Vol. 71 (2017)
       
  • Uncertain reduced-order modeling for unsteady aerodynamics with interval
           parameters and its application on robust flutter boundary prediction
    • Authors: Xianjia Chen; Zhiping Qiu; Xiaojun Wang; Yunlong Li; Ruixing Wang
      Pages: 214 - 230
      Abstract: Publication date: December 2017
      Source:Aerospace Science and Technology, Volume 71
      Author(s): Xianjia Chen, Zhiping Qiu, Xiaojun Wang, Yunlong Li, Ruixing Wang
      Computational fluid dynamics based unsteady aerodynamic reduced-order models can significantly improve the efficiency of transonic aeroelastic analysis. In this paper, the concept of the conventional model reduction method based on the system identification theory is extended to aerodynamic subsystems with the consideration of computational fluid dynamics-induced interval uncertainties in simulation to get the aerodynamic reduced-order model as uncertain as the original aerodynamic subsystem. The interval estimation of identified coefficients involved in the uncertain reduced-order model is obtained by utilizing the first-order interval perturbation method. The stability problem of the interval aeroelastic state-space model formulated based on the constructed uncertain aerodynamic reduced-order model is equivalently transformed into a standard interval eigenvalue problem associated with a real non-symmetric interval matrix in which the interval bounds of eigenvalues are evaluated by virtue of the first-order interval matrix perturbation algorithm. A new stability criterion for the interval aeroelastic state matrix is defined to predict the robust flutter boundary of the concerned uncertain aeroelastic system. Two numerical examples with respect to the uncertain aerodynamic ROM constructions and robust flutter boundary predictions of the two-dimensional Isogai wing and the three-dimensional AGARD 445.6 wing in transonic regime are implemented to assess the validity and accuracy of the presented approach. The obtained results are also compared with Monte Carlo simulation solutions as well as numerical and experimental results in the literatures indicating that the proposed method can provide a more robust and conservative prediction on the flutter boundary of an aeroelastic system compared with conventional deterministic aeroelastic analysis approaches.

      PubDate: 2017-10-08T08:50:02Z
      DOI: 10.1016/j.ast.2017.09.018
      Issue No: Vol. 71 (2017)
       
  • Analysis of the crash of a transport aircraft and assessment of
           fuzzy-logic stall recovery
    • Authors: Chuan-Tau Lan; Shawn Keshmiri
      Pages: 231 - 244
      Abstract: Publication date: December 2017
      Source:Aerospace Science and Technology, Volume 71
      Author(s): Chuan-Tau Lan, Shawn Keshmiri
      A turboprop transport Flight Data Recorder data indicates that attempt to recover from the stalled conditions has failed, even though the pitch angle is continuously pushed nose-down in accordance with the published stall-recovery technique. The present study is to examine the reasons for the angle of attack being increased in the first place and not being reduced after stall, even though the longitudinal control is set to nose-down. Fuzzy Logic models are used to preserve nonlinear and unsteady aerodynamic effects. It is found that the increasing angle of attack is initially caused by the nose-up pitching moment due to inertial coupling. In the subsequent nose-down control attempt for stall recovery, the stall angles of attack are still increasingly higher because the pitch rate relative to the rotating axes stays mostly positive. The present simulation study is based on a new method to be called “Fuzzy-Logic Dynamic Inversion,” where desired dynamics with reduced Euler angles and angular rates are specified; while the required control inputs in elevator, aileron and rudder are determined, all through Fuzzy Logic models. Results in elevator, aileron and rudder controls are illustrated to demonstrate the possibility of stall recovery and accident prevention. It is shown that if at the first sign of stall in icing and crosswind flight conditions, and the landing is aborted, stall recovery is possible by applying proper control inputs simultaneously about three control axes to reduce the moments of inertial coupling and the roll and pitch angles.

      PubDate: 2017-10-08T08:50:02Z
      DOI: 10.1016/j.ast.2017.09.028
      Issue No: Vol. 71 (2017)
       
  • UGV-to-UAV cooperative ranging for robust navigation in GNSS-challenged
           environments
    • Authors: Victor O. Sivaneri; Jason N. Gross
      Pages: 245 - 255
      Abstract: Publication date: December 2017
      Source:Aerospace Science and Technology, Volume 71
      Author(s): Victor O. Sivaneri, Jason N. Gross
      This paper considers cooperative navigation between an Unmanned Aerial Vehicle (UAV) operating in a GNSS-challenged environment with an Unmanned Ground Vehicle (UGV), and focuses on the design of the optimal motion of the UGV to best aide the UAV's navigation solution. Our approach reduces the uncertainty of a UAV's navigation solution through the use of peer-to-peer radio ranging from a cooperative UGV, whose location is designed to improve positioning geometry for the UAV. Two novel cooperative strategies and two different estimation strategies for the UGV to assist a UAV are developed and compared. Through the use of a realistic simulation environment, it is shown that employing UGV-to-UAV cooperative navigation can reduce the positioning error of a UAV that is operating in a GNSS-challenged environment, from approximately 1-meter-level to approximately 10-cm-level 3D positioning error.

      PubDate: 2017-10-08T08:50:02Z
      DOI: 10.1016/j.ast.2017.09.024
      Issue No: Vol. 71 (2017)
       
  • Numerical study of inflow equivalence ratio inhomogeneity on oblique
           detonation formation in hydrogen–air mixtures
    • Authors: Yishen Fang; Zongmin Hu; Honghui Teng; Zonglin Jiang; Hoi Dick Ng
      Pages: 256 - 263
      Abstract: Publication date: December 2017
      Source:Aerospace Science and Technology, Volume 71
      Author(s): Yishen Fang, Zongmin Hu, Honghui Teng, Zonglin Jiang, Hoi Dick Ng
      In this study, numerical simulations using Euler equations with detailed chemistry are performed to investigate the effect of fuel–air composition inhomogeneity on the oblique detonation wave (ODW) initiation in hydrogen–air mixtures. This study aims for a better understanding of oblique detonation wave engine performance under practical operating conditions, among those is the inhomogeneous mixing of fuel and air giving rise to a variation of the equivalence ratio (ER) in the incoming combustible flow. This work focuses primarily on how a variable equivalence ratio in the inflow mixture affects both the formation and characteristic parameters of the oblique detonation wave. In this regard, the present simulation imposes initially a lateral linear distribution of the mixture equivalence ratio within the initiation region. The variation is either from fuel-lean or fuel-rich to the uniform stoichiometric mixture condition above the oblique shock wave. The obtained numerical results illustrate that the reaction surface is distorted in the cases of low mixture equivalence ratio. The so-called “V-shaped” flame is observed but differed from previous results that it is not coupled with any compression or shock wave. Analyzing the temperature and species density evolution also shows that the fuel-lean and fuel-rich inhomogeneity have different effects on the combustion features in the initiation region behind the oblique shock wave. Two characteristic quantities, namely the initiation length and the ODW surface position, are defined to describe quantitatively the effects of mixture equivalence ratio inhomogeneity. The results show that the initiation length is mainly determined by the mixture equivalence ratio in the initiation region. Additional computations are performed by reversing ER distribution, i.e., with the linear variation above the initiation region of uniform stoichiometric condition and results also demonstrate that the ODW position is effectively determined by the ER variation before the ODW, which has in turn only negligible effect on the initiation length.

      PubDate: 2017-10-08T08:50:02Z
      DOI: 10.1016/j.ast.2017.09.027
      Issue No: Vol. 71 (2017)
       
  • A cancelling method based on Nth-order SSC algorithm for solving active
           cancellation problems
    • Authors: Mingxu Yi; Jun Huang; Zhijun Meng
      Pages: 264 - 271
      Abstract: Publication date: December 2017
      Source:Aerospace Science and Technology, Volume 71
      Author(s): Mingxu Yi, Jun Huang, Zhijun Meng
      In this paper, a mathematical model of cancelling signal on the basis of Nth-order SSC (Spectrum Spread and Compression) algorithm is established for the Nonlinear Frequency Modulated (NLFM) signal. The explicit expressions of these cancelling signals are derived. Simulation results show that the cancelling signal could reduce the target gain when the time delay is relatively large. The proposed method is compared with the existing methods in the literature and satisfactory results obtained. Comparison between active cancellation technology and passive stealth technology is implemented in detail. The discussions demonstrate that active cancellation technology is more applicable to solve the low-frequency stealth problem.

      PubDate: 2017-10-08T08:50:02Z
      DOI: 10.1016/j.ast.2017.09.038
      Issue No: Vol. 71 (2017)
       
  • Finite-time tracking control of hypersonic vehicle with input saturation
    • Authors: Jing-Guang Sun; Sheng-Li Xu; Shen-Min Song; Xi-Jun Dong
      Pages: 272 - 284
      Abstract: Publication date: December 2017
      Source:Aerospace Science and Technology, Volume 71
      Author(s): Jing-Guang Sun, Sheng-Li Xu, Shen-Min Song, Xi-Jun Dong
      This paper studies the finite-time tracking control problem of hypersonic vehicle in presence of model parameter uncertainties, external disturbance and input saturation. Firstly, to cope with the unknown upper bound disturbance of the system, an adaptive fast terminal sliding mode controller is designed based on a non-homogeneous disturbance observer (NHDO) which can alleviate the chattering and make the proposed controller strongly robust. Meanwhile, a new saturation function is introduced to solve the singular problems of the controller. Secondly, to further solve the problem of input saturation, the hyperbolic tangent function and auxiliary system are introduced to design an anti-saturation fast adaptive terminal sliding mode controller which not only can satisfy the requirements of the actuator's physical limitation, but also guarantees that the sliding mode manifold is finite-time stable. Finally, Lyapunov theory is used to prove the stability of the designed controller strictly, and the numerical simulations of the longitudinal model of the hypersonic vehicle are carried out, which further confirm the robustness and effectiveness of the two designed controllers.

      PubDate: 2017-10-14T08:55:28Z
      DOI: 10.1016/j.ast.2017.09.036
      Issue No: Vol. 71 (2017)
       
  • Monitoring multi-axial vibrations of flexible rockets using
           sensor-instrumented reference strain structures
    • Authors: Natsuki Tsushima; Weihua Su; Hector Gutierrez; Michael G. Wolf; Edwin D. Griffin; Jarrod T. Whittaker; Marie P. Dumoulin
      Pages: 285 - 298
      Abstract: Publication date: December 2017
      Source:Aerospace Science and Technology, Volume 71
      Author(s): Natsuki Tsushima, Weihua Su, Hector Gutierrez, Michael G. Wolf, Edwin D. Griffin, Jarrod T. Whittaker, Marie P. Dumoulin
      Strain sensors (e.g., fiber optic strain sensors) can be used to measure the deformation of flexible rockets during launches, in order to monitor and control rocket flight attitude. In this paper, strain sensors are instrumented on multi-axial reference strain structures for a convenient monitor of rocket bending vibrations. Reference strain structures are attached longitudinally along the outer surface of thin-walled flexible rockets. As the medium between the sensors and rocket, the structural design of reference strain structures, as well as the sensor spacing along them, is optimized using an integrated multi-objective optimization approach, which ensures that the reference strain structures will accurately track the deformation of the rocket surface. In addition, kinematic equations are developed to allow for an accurate prediction of the bending deflection of the rocket center axis by using the strain data measured on the rocket surface. Finally, the performance of the optimal reference strain structure is evaluated using different numerical simulations of the flexible rocket.

      PubDate: 2017-10-14T08:55:28Z
      DOI: 10.1016/j.ast.2017.09.026
      Issue No: Vol. 71 (2017)
       
  • Influences of shield ratio on the infrared signature of serpentine nozzle
    • Authors: Wen Cheng; Zhanxue Wang; Li Zhou; Xiaolin Sun; Jingwei Shi
      Pages: 299 - 311
      Abstract: Publication date: December 2017
      Source:Aerospace Science and Technology, Volume 71
      Author(s): Wen Cheng, Zhanxue Wang, Li Zhou, Xiaolin Sun, Jingwei Shi
      The criteria for designing the serpentine nozzle on the aspect of infrared suppression is undocumented currently. The aim of this paper is to investigate the influences of the shield ratio on the infrared signature of the serpentine nozzle. Firstly, a validation study was conducted to get the reliable computational method of the infrared signature. Then, the infrared signatures of the serpentine nozzles with variable shield ratios were investigated numerically, and the comparison between the serpentine nozzle and the circular nozzle was also conducted. Results show that 28.9% of the infrared radiation intensity, on average, can be reduced by the single serpentine nozzle, as compare with the circular nozzle. The shield ratio has little effect on the infrared signature of gas outside of the serpentine nozzle exit. And the completely shielded serpentine nozzle cannot bring the greatest benefit to the infrared stealth. The single serpentine nozzle with shield ratio of 0.75 and the double serpentine nozzle with shield ratio of 0.5 have better infrared stealth performance than the others. The visible area ratio can be used as an indicator to evaluate the infrared signature of the serpentine nozzle. In order to provide an effective infrared suppression, the visible area ratio of the single serpentine nozzle and the double serpentine nozzle should be restricted under 0.15 and 0.35, respectively.

      PubDate: 2017-10-14T08:55:28Z
      DOI: 10.1016/j.ast.2017.09.001
      Issue No: Vol. 71 (2017)
       
  • Multi-objective optimization for re-entry spacecraft conceptual design
           using a free-form shape generator
    • Authors: Antonio Viviani; Luigi Iuspa; Andrea Aprovitola
      Pages: 312 - 324
      Abstract: Publication date: December 2017
      Source:Aerospace Science and Technology, Volume 71
      Author(s): Antonio Viviani, Luigi Iuspa, Andrea Aprovitola
      In this paper we developed a multi-disciplinary, multi-objective optimization procedure for the shape generation of re-entry spacecrafts performing conventional landing from a Low Earth Orbit return mission. A special free-form parametric model, able to define complex vehicle shapes with no explicit support surfaces, was defined and used for this purpose. Model capabilities have been preliminary validated by emulating the HOPE-X vehicle prototype and computing the aerodynamic coefficients at Mach number 2 and 10. Multi-objective optimization has been performed by considering a multidisciplinary approach comprising aerodynamic analysis, trajectory estimation, and heating analysis starting by fixed waypoints along the descent path. A Pareto front based on mass and cross range objective functions was generated, highlighting the existence of several design scenarios: minimum mass, maximum winglet, maximum cross range. The existing trade-offs between the objective functions were related mainly to bank angle values and vehicle length, featuring main design trends.

      PubDate: 2017-10-14T08:55:28Z
      DOI: 10.1016/j.ast.2017.09.030
      Issue No: Vol. 71 (2017)
       
  • Conceptual design, performance and stability analysis of a 200 passengers
           Blended Wing Body aircraft
    • Authors: Sami Ammar; Clément Legros; Jean-Yves Trépanier
      Pages: 325 - 336
      Abstract: Publication date: December 2017
      Source:Aerospace Science and Technology, Volume 71
      Author(s): Sami Ammar, Clément Legros, Jean-Yves Trépanier
      The Blended Wing Body (BWB) is a type of innovative aircraft, based on the flying wing concept. For this aircraft, the literature has reported performance improvements compared to conventional aircraft: economy of fuel, reduction of the weight of the structure, increased payload capacity and less impact on the environment. However, most BWB studies have focused on large aircraft and it is not sure whether the gains are the same for smaller aircraft. The main objective of this study is to perform the conceptual design of a 200 passengers BWB and compare its performance against an equivalent conventional A320 aircraft in terms of payload and range. Moreover, an emphasis will be placed on obtaining a stable aircraft, with the analysis of static and dynamic stability over its flight envelope. This kind of aircraft has a lack of stability due to the absence of vertical tail. Most studies of stability were already realized on reduced size models of BWB, but there is no study on a 200 passengers BWB. The design of the BWB was realized with the platform called Computerized Environment for Aircraft Synthesis and Integrated Optimization Methods (CEASIOM). The airplane, the engines and the control surfaces were obtained in the geometrical module AcBuilder. This design platform, suitable for conventional aircraft design, has been modified and additional tools have been integrated in order to achieve the aerodynamic, performance and stability analysis of the BWB aircraft. The aerodynamic coefficients are calculated from Tornado program. The BWB flight envelope was created based on aeronautical data of A320 aircraft. From this flight envelope, we have got back several thousand possible points of flight. The static and dynamic stability was studied using the longitudinal and lateral matrices of stability and the Flying Qualities Requirements for every flight point.

      PubDate: 2017-10-14T08:55:28Z
      DOI: 10.1016/j.ast.2017.09.037
      Issue No: Vol. 71 (2017)
       
  • Spiral coning manoeuvre for in-orbit low thrust characterisation in
           CubeSats
    • Authors: A. Macario-Rojas; K.L. Smith
      Pages: 337 - 346
      Abstract: Publication date: December 2017
      Source:Aerospace Science and Technology, Volume 71
      Author(s): A. Macario-Rojas, K.L. Smith
      The ability to accurately measure the level of thrust during in-orbit operations is fundamental to the characterisation of emerging propulsion systems for nanosatellites. Many new CubeSat missions use propulsion systems with thrust levels in the order of few micro-Newtons. Whilst laboratory sensing resources are able to resolve such low thrust values, in complementary in-orbit characterisation are limited and in the main not compatible with the standard CubeSat mission. Additionally, typical in-orbit assessment of micro-thrust is generally carried out through body angular speed changes, the effectiveness of which is drastically reduced when external perturbations and sensor noise approach or exceed the thruster action on the CubeSat. This investigation sets out to improve in-orbit micro-thrust characterisation via changes in body angular velocity periodicity due to off-centred thrust action in nearly axisymmetric CubeSats. Unlike traditional methods that rely on determining angular acceleration this method employs a frequency analysis of the transversal component of the angular velocity signal with the aim of reducing measurement error. Numerical simulations support the feasibility and adequacy of the proposed low-thrust gauging method, particularly for weak and noisy sensor signals. The robustness of the method allows for interchangeable analysed signal and enables the use of simple commercial-off-the-shelf rate sensors in fine micro-thrust characterisation.

      PubDate: 2017-10-14T08:55:28Z
      DOI: 10.1016/j.ast.2017.09.035
      Issue No: Vol. 71 (2017)
       
  • Effect of elastic deformation on flight dynamics of projectiles with large
           slenderness ratio
    • Authors: RuHao Hua; ZhengYin Ye; Jie Wu
      Pages: 347 - 359
      Abstract: Publication date: December 2017
      Source:Aerospace Science and Technology, Volume 71
      Author(s): RuHao Hua, ZhengYin Ye, Jie Wu
      The elastic deformation of modern projectiles with large slenderness ratio cannot be ignored with the increasing of flight speed and maneuverability. Unsteady Reynolds-averaged Navier–Stokes (URANS) Equations are solved through CFD technique in this paper. Based on the frame of unstructured mesh, techniques of rigid-motion mesh and inverse-distance-weighted (IDW) morphing mesh are adopted to treat the rigid motion caused by flight dynamics and flexible structure deformation due to aeroelasticity, respectively. Moreover, the six degree of freedom (SDOF) dynamic equations and static aeroelastic equation are solved through the aerodynamic coupling. Numerical results of both free flight case and aeroelastic case calculated by the in-house code agree well with the experimental data, validating the numerical method. A projectile model with X–X configuration is constructed to investigate the effect of elastic deformation on the flight dynamics. Comparison results show that the longitudinal oscillation is more affected by the elastic deformation than the centroid motion, and the oscillation cycle of the orientation angle increases. Furthermore, the trajectories of rigid models with various centroid locations are simulated, illustrating that the elastic deformation could move the aerodynamic center forward and weaken the margin of the static stability margin. In the end, detailed analysis and comparison of the pressure distribution indicates the mechanism by which the elastic deformation leads to the movement of the aerodynamic center and changes the flight dynamic characteristics of the flexible projectile.

      PubDate: 2017-10-14T08:55:28Z
      DOI: 10.1016/j.ast.2017.09.029
      Issue No: Vol. 71 (2017)
       
  • New approach to investigate nonlinear dynamic response and vibration of
           imperfect functionally graded carbon nanotube reinforced composite double
           curved shallow shells subjected to blast load and temperature
    • Authors: Dinh Duc Nguyen; Quoc Quan Tran; Dinh Khoa Nguyen
      Pages: 360 - 372
      Abstract: Publication date: December 2017
      Source:Aerospace Science and Technology, Volume 71
      Author(s): Dinh Duc Nguyen, Quoc Quan Tran, Dinh Khoa Nguyen
      This paper presents a new approach – using analytical solution to investigate nonlinear dynamic response and vibration of imperfect functionally graded carbon nanotube reinforced composite (FG-CNTRC) double curved shallow shells. The double curved shallow shells are reinforced by single-walled carbon nanotubes (SWCNTs) which vary according to the linear functions of the shell thickness. The shells are resting on elastic foundations and subjected to blast load and temperature. The shell's effective material properties are assumed to depend on temperature and estimated through the rule of mixture. By applying higher order shear theory, Galerkin method and fourth-order Runge–Kutta method and the Airy stress function, nonlinear dynamic response and natural frequency for thick imperfect FG-CNTRC double curved shallow shells are determined. In numerical results, the influences of geometrical parameters, elastic foundations, initial imperfection, temperature increment and nanotube volume fraction on the nonlinear vibration of the FG-CNTRC double curved shallow shells are investigated. The proposed results are validated by comparing with those of other authors.

      PubDate: 2017-10-14T08:55:28Z
      DOI: 10.1016/j.ast.2017.09.031
      Issue No: Vol. 71 (2017)
       
  • Adaptive optimal gliding guidance independent of QEGC
    • Authors: Jianwen Zhu; Shengxiu Zhang
      Pages: 373 - 381
      Abstract: Publication date: December 2017
      Source:Aerospace Science and Technology, Volume 71
      Author(s): Jianwen Zhu, Shengxiu Zhang
      A novel multiple constrained adaptive gliding guidance method which is independent of quasi-equilibrium gliding condition (QEGC) and standard trajectory is proposed in this paper. The gliding guidance task is decomposed into longitudinal and lateral directions. In longitudinal direction, an altitude control model is established independent of QEGC, a hierarchical adaptive guidance strategy is introduced to control the vehicle to achieve equilibrium flight state and to meet the terminal altitude and flight-path angle constraints. In lateral direction, a heading error control model is constructed and the optimal control is employed to eliminate the heading error in real time with minimum energy consumption. In addition, the terminal velocity magnitude is predicted and corrected analytically based on lift–drag ratio, and the coordination strategy between guidance and velocity control is proposed to realize multi-constraint gliding guidance. This algorithm can generate angle-of-attack and bank angle commands which can meet the given terminal constraints with high precision based on the current flight states analytically, and has strong robustness to the initial deviation and environmental deviation.

      PubDate: 2017-10-14T08:55:28Z
      DOI: 10.1016/j.ast.2017.09.033
      Issue No: Vol. 71 (2017)
       
  • An investigation on the effect of pitchwise endwall design in a turbine
           cascade at different incidence angles
    • Authors: K.N. Kiran; S. Anish
      Pages: 382 - 391
      Abstract: Publication date: December 2017
      Source:Aerospace Science and Technology, Volume 71
      Author(s): K.N. Kiran, S. Anish
      This paper describes the effects of non-axisymmetric endwall profiling on the aerodynamic performance of a linear turbine cascade at different incidence angles. The sinusoidal profiling is carried out with constant profile curvature along the mean streamline path. Three different profiles, with varying hump to dip height, are analyzed numerically and the performances are compared with the planar profile. Reynolds Averaged Navier Stokes (RANS) equations are solved in their conservative form using Finite Volume Method with SST turbulence model. The calculated results indicate that the profiled endwall minimizes the lateral movement of weaker boundary layer fluid from the hub-pressure side corner. In comparison with planar case, the flow deviations are largely contained with endwall profiling but closer to the endwall it enhances the overturning and secondary flow kinetic energy. The reduction in loss coefficient is estimated to be 1.3%, 8.7% and 38% for incidence angles of −10°, nominal and +15° respectively. The sinusoidal profiling has brought down the pitch averaged flow deviation and secondary flow kinetic energy at nominal and positive incidence angles but the impact is insignificant at negative incidence. Profiling minimizes the rolling up of the passage vortex and makes the passage vortex to migrate closer to the endwall. This flow modification brings down the losses in the core flow but enhances the losses near the endwall.

      PubDate: 2017-10-14T08:55:28Z
      DOI: 10.1016/j.ast.2017.09.032
      Issue No: Vol. 71 (2017)
       
  • A multi-source information fusion fault diagnosis for aviation hydraulic
           pump based on the new evidence similarity distance
    • Authors: Chuanqi Lu; Shaoping Wang; Xingjian Wang
      Pages: 392 - 401
      Abstract: Publication date: December 2017
      Source:Aerospace Science and Technology, Volume 71
      Author(s): Chuanqi Lu, Shaoping Wang, Xingjian Wang
      Aviation hydraulic pump is one of the key components in aircraft hydraulic system, therefore, high-precision fault diagnosis is essential to improve the reliability and performance of hydraulic pump. A novel multi-source information fusion fault diagnosis method is proposed based on the Dempster–Shafer (D–S) evidence theory, which utilizes the three-level signals from pump level, hydraulic power system level and hydraulic actuation system level. The feature vectors of these three levels are extracted as three bodies of evidences (BOEs) and the fuzzy membership function is employed to construct the basic probability assignments (BPAs) of three BOEs. In order to solve the issue of combining the conflicting evidences, the D–S evidence theory based on the new evidence similarity distance is developed to combine the obtained BPAs. Finally, the making-decision rules are given to diagnose the faults. The diagnosis results validate that the proposed method not only can increase significantly the belief level of supporting the diagnosis target, but also has the ability to diagnose fault of pump correctly even if a sensor is faulty.

      PubDate: 2017-10-14T08:55:28Z
      DOI: 10.1016/j.ast.2017.09.040
      Issue No: Vol. 71 (2017)
       
  • On the thermo-structural response of a composite closeout in a
           regeneratively cooled thrust chamber
    • Authors: M. Ferraiuolo; W. Petrillo; A. Riccio
      Pages: 402 - 411
      Abstract: Publication date: December 2017
      Source:Aerospace Science and Technology, Volume 71
      Author(s): M. Ferraiuolo, W. Petrillo, A. Riccio
      Composite materials could be very useful when applied to structural rocket engine components since they can allow significant weight savings thanks to their high specific strength and high specific stiffness. In the present work, a carbon fiber reinforced composite has been adopted to replace the typical heavy metallic closeout structure of a regeneratively cooled thrust chamber of a liquid rocket engine. The composite structure has been considered wrapped over the inner liner of the thrust chamber, made of copper alloys, and provides hoop strength for withstanding the fuel/coolant pressure in the cooling channels. The main aim of the paper is to investigate the influence of the geometry and the thermo-mechanical load on the structural response of the analyzed composite closeout. This study is expected to provide a better understanding of the physical phenomena occurring during the service life of the chamber together with an effective identification of the sizing loads that should be considered in the design phase of the closeout structure.

      PubDate: 2017-10-14T08:55:28Z
      DOI: 10.1016/j.ast.2017.09.041
      Issue No: Vol. 71 (2017)
       
  • Multidisciplinary optimisation of single-stage sounding rockets using
           solid propulsion
    • Authors: Adam Okninski
      Pages: 412 - 419
      Abstract: Publication date: December 2017
      Source:Aerospace Science and Technology, Volume 71
      Author(s): Adam Okninski
      Existing sounding rockets are based on earlier proven designs and often utilize surplus military solid rocket motors. Therefore commonly non-optimal, in terms of performance for a given payload, configurations are utilized. This paper presents a methodology for finding close-to-optimal, in terms of launch mass minimization, design configurations for small unguided sounding rockets. A numerical, multidisciplinary approach is used. During the optimization process vehicle sizing and corresponding aerodynamics modelling is done. The implemented flight simulation module is simplified due to unknown, during the conceptual design phase, rocket mass distributions along vehicle major axes. Special attention is given to propulsion system sizing and thrust level selection. This paper presents optimization of sounding rockets with lift capabilities equivalent to sending small payloads above the Von Karman line. The ultimate aim of this paper is to present methods to improve sounding rocket performance at an early stage of design, to enable conducting more efficient microgravity research. Various concepts, such as using different expansion ratio nozzles for different payload envelopes and masses, are discussed. Optimization results for maximizing the apogee of a small sounding rocket are presented. Due to the lack of published corresponding research, guidelines for future sounding rocket developments, based on numerical investigations, are given. The significance of the study is due to the emergence of new sounding rocket designs, without use of surplus motors, and the possibility to improve vehicle efficiency after a few decades of little alteration.

      PubDate: 2017-10-14T08:55:28Z
      DOI: 10.1016/j.ast.2017.09.039
      Issue No: Vol. 71 (2017)
       
  • Preliminary integrated analysis for modeling and optimizing space stations
           at conceptual level
    • Authors: Kaiqiang Wang; Bainan Zhang; Tao Xing
      Pages: 420 - 431
      Abstract: Publication date: December 2017
      Source:Aerospace Science and Technology, Volume 71
      Author(s): Kaiqiang Wang, Bainan Zhang, Tao Xing
      Key disciplines at the conceptual design stage for space station are introduced, which are configuration, dynamics and control, and power disciplines. The main variables and parameters in the three disciplines are presented, and the relevant disciplinary analysis models are developed. The integrated analysis framework of the space station is obtained afterward. Then, the multidisciplinary optimization for solar array configuration is taken as an example of the space station optimization based on the integrated analysis model. The optimization problem is modeled with the use of the collaborative optimization (CO). The system-level and three disciplinary optimization models are introduced. In the optimization process, MATLAB is utilized for simulation, and the adaptive genetic algorithm (AGA) is applied as the basic optimization algorithm. It is shown that the optimization problem is effectively solved with the use of the CO and AGA. Moreover, using the integrated analysis framework, the parameters of space station are successfully calculated with high computational efficiency at the conceptual design stage.

      PubDate: 2017-10-14T08:55:28Z
      DOI: 10.1016/j.ast.2017.09.048
      Issue No: Vol. 71 (2017)
       
  • Nussbaum-based fuzzy adaptive nonlinear fault-tolerant control for
           hypersonic vehicles with diverse actuator faults
    • Authors: Chaofang Hu; Xianpeng Zhou; Binghan Sun; Wenjing Liu; Qun Zong
      Pages: 432 - 440
      Abstract: Publication date: December 2017
      Source:Aerospace Science and Technology, Volume 71
      Author(s): Chaofang Hu, Xianpeng Zhou, Binghan Sun, Wenjing Liu, Qun Zong
      Stability is a challenging problem for control system of the hypersonic vehicle when partial loss of effectiveness fault and stuck fault happen on elevators and engine. In this paper, a fuzzy adaptive nonlinear fault-tolerant control (FTC) method based on Nussbaum gain technique is proposed for hypersonic vehicles with diverse faults. The cases that one of elevators is lock-in-place and another elevator or the engine is partial loss of effectiveness are addressed. The longitudinal model is transformed into the strict feedback formation. The baseline controllers for altitude and velocity commands tracking are designed using dynamic surface control (DSC) and dynamic inversion. The partial loss of effectiveness faults of elevators and engine are combined in the control gain functions, and Nussbaum approach is introduced to avoid singularity of controllers. The unknown nonlinear functions involving the stuck fault and original uncertain nonlinear items are approximated by fuzzy logic systems. The norm estimation technique is utilized to reduce the number of fuzzy adaptive parameters. This greatly alleviates the calculation burden. It is guaranteed that all signals of the closed-loop FTC system are semi-global uniformly ultimately bounded. Finally, the numerical simulations involving diverse faults demonstrate the effectiveness of the proposed FTC approach.

      PubDate: 2017-10-14T08:55:28Z
      DOI: 10.1016/j.ast.2017.10.002
      Issue No: Vol. 71 (2017)
       
  • Two-dimensional heliocentric dynamics approximation of an electric sail
           with fixed attitude
    • Authors: Lorenzo Niccolai; Alessandro A. Quarta; Giovanni Mengali
      Pages: 441 - 446
      Abstract: Publication date: December 2017
      Source:Aerospace Science and Technology, Volume 71
      Author(s): Lorenzo Niccolai, Alessandro A. Quarta, Giovanni Mengali
      This work analyzes an approximate solution of the equations of motion for a spacecraft propelled by an Electric Solar Wind Sail with a fixed attitude. The peculiarity of such a propulsion system is that its thrust scales as the inverse heliocentric distance. This represents a substantial difference from a classical solar sail, whose propelling force is known to be proportional to inverse square distance from the Sun. Assuming a heliocentric, two-dimensional mission scenario, the polar form of the spacecraft trajectory equation is obtained for a closed parking orbit of given characteristics by means of an asymptotic expansion procedure. The proposed approach significantly improves the existing results as presented in the literature. A suitable choice of propulsion system parameters and parking orbit characteristics provides interesting similarities with recent solutions obtained for a solar sail-based spacecraft in a heliocentric, two-dimensional, mission scenario.

      PubDate: 2017-10-14T08:55:28Z
      DOI: 10.1016/j.ast.2017.09.045
      Issue No: Vol. 71 (2017)
       
  • Enhancement of quality of modal test results of an unmanned aerial vehicle
           wing by implementing a multi-objective genetic algorithm optimization
    • Authors: Nima Pedramasl; Melin Şahin; Erdem Acar
      Pages: 447 - 463
      Abstract: Publication date: December 2017
      Source:Aerospace Science and Technology, Volume 71
      Author(s): Nima Pedramasl, Melin Şahin, Erdem Acar
      Due the fact that aircraft structures work in an environment with lots of dynamic forces, it is of vital importance to perform a dynamic analysis to understand dynamic characteristics of aircraft in that specific environment. These characteristics are usually obtained using numerical methods (finite element analysis) or experimental methods (classical modal analysis). In classical modal analysis, quality of test equipment plays a critical role in final results' accuracy and completeness. There is another important factor which is expertise of a test engineer. Test engineer uses his/her experience to find sufficient/optimum numbers, types and locations of transducers. This process sometimes would be time consuming and exhausting which results in degradation of test results quality. In this paper an algorithm is developed and implemented to find numbers, types and locations of transducers in a modal test which will make results of test more reliable. In this study, an unmanned aerial vehicle used as dummy structure to test functionality of developed algorithm. This algorithm utilized two toolboxes from MATLAB (multi-objective genetic algorithm toolbox and parallel computing toolbox) and MSC© NASTRAN finite element solver. A genetic algorithm based optimization is performed in which MSC© NASTRAN was used to calculate dynamic characteristics of UAV wing. Since this was a time and resource consuming process a parallel computing cluster is also utilized which decreased run times at least fourfold. In algorithm it was tried to find optimum numbers, types and locations of transducers which will result in minimum cost and error in test results. Error was defined as a summation of mode shape observability error, mass loading error and optimum driving point error. At the end of study optimization results are presented and validated by classical modal analysis.

      PubDate: 2017-10-14T08:55:28Z
      DOI: 10.1016/j.ast.2017.09.042
      Issue No: Vol. 71 (2017)
       
  • Inertia parameters identification for cellular space robot through
           interaction
    • Authors: Haitao Chang; Panfeng Huang; Zhenyu Lu; Yizhai Zhang; Zhongjie Meng; Zhengxiong Liu
      Pages: 464 - 474
      Abstract: Publication date: December 2017
      Source:Aerospace Science and Technology, Volume 71
      Author(s): Haitao Chang, Panfeng Huang, Zhenyu Lu, Yizhai Zhang, Zhongjie Meng, Zhengxiong Liu
      Most of the technologies are in high-speed evolution nowadays. But the spacecraft, however, is still high-priced and takes years to construct. Besides that, it is hardly to service since the conventional spacecraft are not serviceable designed. Facing those challenges, the concept of cellular space robot is presented in this paper for both spacecraft system construction and on-orbit service. As a typical on-orbit service task, the non-cooperative target takeover control is considered in this paper. Specifically, the inertia parameters identification for takeover control is studied in this paper. Because the cells in the cellular space robot are interconnected and networked, an interactive parameter identification algorithm is presented to solve the parameter identification problem by cells interaction. The algorithm is distributed and both synchronous and asynchronous interactions are supported. The algorithm is validated and analyzed by numerical simulations.

      PubDate: 2017-10-14T08:55:28Z
      DOI: 10.1016/j.ast.2017.09.044
      Issue No: Vol. 71 (2017)
       
  • Deployment strategies for planar multi-tethered satellite formation
    • Authors: Guang Zhai; Fei Su; Jingrui Zhang; Bin Liang
      Pages: 475 - 484
      Abstract: Publication date: December 2017
      Source:Aerospace Science and Technology, Volume 71
      Author(s): Guang Zhai, Fei Su, Jingrui Zhang, Bin Liang
      This paper presents the deployment strategies for planar multi-tethered satellite formation that spins in orbit plane. By using Lagrange principles, the deployment dynamics, which treat the parent satellite as a finite sized rigid body, are established under gravity gradient perturbation. Comparing with the simplified dynamics that take the parent satellite as mass point, the model in this work enables the investigation on dynamical coupling between parent satellite and tethers. To achieve successful deployment, typical strategies are developed firstly with active gravity gradient compensation, both the tether deployment rate and parent satellite spinning profile are derived under specific motion constraints, after that, the deployment strategy capable of compensating the gravity gradient perturbation is also developed. For the fully deployed system, the minimum spinning rate that ensures the configuration stabilization is mathematically analyzed by employing Jacobi Integrator. Finally, series numerical simulations are performed to validate the proposed deployment strategies.

      PubDate: 2017-10-14T08:55:28Z
      DOI: 10.1016/j.ast.2017.10.009
      Issue No: Vol. 71 (2017)
       
  • A prescribed performance control approach guaranteeing small overshoot for
           air-breathing hypersonic vehicles via neural approximation
    • Authors: Xiangwei Bu; Yu Xiao; Ke Wang
      Pages: 485 - 498
      Abstract: Publication date: December 2017
      Source:Aerospace Science and Technology, Volume 71
      Author(s): Xiangwei Bu, Yu Xiao, Ke Wang
      This paper investigates a new prescribed performance control (PPC) methodology for the longitudinal dynamic model of an air-breathing hypersonic vehicle via neural approximation. To release the restriction on traditional PPC that the initial tracking errors have to be known in advance for control design, a novel performance function is exploited. Moreover, the devised controller is capable of guaranteeing prescribed performance on the velocity and altitude tracking errors. Neural networks (NNs) are employed to approximate the unknown vehicle dynamics and a minimal-learning parameter scheme is utilized to update the norm of NN's weight vector. Hence, a low computational burden design is achieved without using back-stepping. The semi-globally uniform boundedness of all the closed-loop signals is insured by Lyapunov synthesis. Finally, simulation results are presented to validate the efficacy of the proposed control approach.

      PubDate: 2017-10-14T08:55:28Z
      DOI: 10.1016/j.ast.2017.10.005
      Issue No: Vol. 71 (2017)
       
  • LQG based model predictive control for gust load alleviation
    • Authors: Xiang Liu; Qin Sun; J.E. Cooper
      Pages: 499 - 509
      Abstract: Publication date: December 2017
      Source:Aerospace Science and Technology, Volume 71
      Author(s): Xiang Liu, Qin Sun, J.E. Cooper
      A linear quadratic Gaussian (LQG) based model predictive control (MPC) method is proposed to alleviate the dynamic gust loads of flexible aircrafts flying through turbulence, utilizing look-ahead information of the turbulence via light detection and ranging (LIDAR) systems or on board alpha probe. The new method features both infinite prediction horizon and infinite control horizon. The forepart of the infinite control sequence consists of a few online optimized variables, and the rest are outputs of an LQG controller, designed offline using an improved LQG method. The advantages of the proposed method are twofold. Firstly, the stability property of the controlled system is improved due to application of the infinite prediction horizon and the LQG controller. Secondly, adoption of an infinite control horizon not only improves the control performance, but also greatly reduces the number of online optimized control variables whilst retaining control performance. Furthermore, a technique to tackle the effects of control delay is also designed. The effectiveness and advantages of the proposed approach are demonstrated through numerical results using a general transport aircraft model.

      PubDate: 2017-10-14T08:55:28Z
      DOI: 10.1016/j.ast.2017.10.006
      Issue No: Vol. 71 (2017)
       
  • A novel crater recognition based visual navigation approach for asteroid
           precise pin-point landing
    • Authors: Yang Tian; Meng Yu
      Pages: 1 - 9
      Abstract: Publication date: November 2017
      Source:Aerospace Science and Technology, Volume 70
      Author(s): Yang Tian, Meng Yu
      This paper proposes a novel terrain-relative navigation (TRN) approach for the asteroid pin-point landing mission. The key concept is encapsulating efficient crater matching with active LiDAR ranging. Importantly, a novel crater to 3D crater model matching approach is proposed. Then, the line-of-sight from lander to crater is employed to guide the LiDAR ranging, and parameters of the matched 3D crater model is efficiently fused with LiDAR ranging to compensate its measurement, resulting in the robustness against the variation of terrain relief. In addition, a crater selection mechanism is proposed to reduce the estimation uncertainty. Monte Carlo simulation results show that the proposed approach is able to provide an adequate navigation performance under a high terrain relief, which is an evident improvement over the traditional methods.

      PubDate: 2017-08-28T11:16:01Z
      DOI: 10.1016/j.ast.2017.07.014
      Issue No: Vol. 70 (2017)
       
  • Control of large amplitude vibrations of doubly curved sandwich shells
           composed of fuzzy fiber reinforced composite facings
    • Authors: R. Suresh Kumar; S.I. Kundalwal; M.C. Ray
      Pages: 10 - 28
      Abstract: Publication date: November 2017
      Source:Aerospace Science and Technology, Volume 70
      Author(s): R. Suresh Kumar, S.I. Kundalwal, M.C. Ray
      This paper is concerned with the analysis of active constrained layer damping (ACLD) of geometrically nonlinear vibrations of doubly curved sandwich shells with facings composed of fuzzy fiber reinforced composite (FFRC). FFRC is a novel composite where the short carbon nanotubes (CNTs) which are either straight or wavy are radially grown on the periphery of the long continuous carbon fiber reinforcements. The plane of waviness of the CNTs is coplanar with the plane of carbon fiber. The constraining layer of the ACLD treatment is composed of the vertically/obliquely reinforced 1–3 piezoelectric composites (PZCs) while the constrained viscoelastic layer has been sandwiched between the substrate and the PZC layer. The Golla–Hughes–McTavish (GHM) method has been implemented to model the constrained viscoelastic layer of the ACLD treatment in time domain. A three dimensional finite element (FE) model of smart doubly curved FFRC sandwich shells integrated with ACLD patches has been developed to investigate the performance of these patches for controlling the geometrically nonlinear vibrations of these shells. This study reveals that the performance of the ACLD patches for controlling the geometrically nonlinear vibrations of the doubly curved sandwich shells is better in the case of the facings composed of laminated FFRC than that in the case of the facings made of conventional orthotropic laminated composite. The research carried out in this paper brings to light that even the wavy CNTs can be properly utilized for attaining structural benefits from the exceptional elastic properties of CNTs.

      PubDate: 2017-08-28T11:16:01Z
      DOI: 10.1016/j.ast.2017.07.027
      Issue No: Vol. 70 (2017)
       
  • A closed-form 3D shell solution for multilayered structures subjected to
           different load combinations
    • Authors: Salvatore Brischetto
      Pages: 29 - 46
      Abstract: Publication date: November 2017
      Source:Aerospace Science and Technology, Volume 70
      Author(s): Salvatore Brischetto
      Multilayered composite and sandwich plates and shells are typical aerospace structures. They introduce complicating effects such as in-plane and transverse anisotropy which lead to zigzag forms of displacement and interlaminar continuity problems. The present closed-form 3D shell solution allows the static analysis of simply-supported cross-ply laminated and sandwich plates, cylinders and cylindrical/spherical shell panels subjected to different harmonic load types. It is possible to consider transverse normal and transverse shear loads simultaneously or separately applied at the top and at the bottom of the considered structure. The present work extends the previous exact 3D shell model developed for the static analysis of plates and shells in the case of transverse normal load applied at the top or at the bottom of the investigated structure. This new extension is still based on the 3D equilibrium equations written in general orthogonal curvilinear coordinates. The obtained system is solved using simply supported boundary conditions, harmonic forms for loads and displacements, a general layer wise approach and the exponential matrix method for the solution of the differential equations in z. However, the load boundary conditions introduced in the proposed shell model have been opportunely modified in order to allow the combination of different transverse normal and transverse shear loads applied at the external surfaces. The new proposed benchmarks fill the gap present in the literature where the proposed 3D exact models always use a transverse normal load applied at the external surfaces. The present paper investigates the zigzag effects, the interlaminar continuity, the equilibrium and compatibility conditions, the load boundary conditions, the symmetry characteristics, the thickness ratio effect and the 3D behavior in laminated and sandwich plates and shells in the case of different load applications. The new proposed benchmarks will be fundamental for the validation of those new refined 2D shell models which want to capture all these features for different load types.

      PubDate: 2017-08-28T11:16:01Z
      DOI: 10.1016/j.ast.2017.07.040
      Issue No: Vol. 70 (2017)
       
  • Target detection in sea clutter via weighted averaging filter on the
           Riemannian manifold
    • Authors: Xiaoqiang Hua; Yongqiang Cheng; Yubo Li; Yifei Shi; Hongqiang Wang; Yuliang Qin
      Pages: 47 - 54
      Abstract: Publication date: November 2017
      Source:Aerospace Science and Technology, Volume 70
      Author(s): Xiaoqiang Hua, Yongqiang Cheng, Yubo Li, Yifei Shi, Hongqiang Wang, Yuliang Qin
      This paper proposes a weighted averaging filter procedure combined with a Riemannian geometry method to carry out a target detection in sea clutter. In particular, the weighted averaging filter, conceived from a philosophy of the bilateral filtering in image denoising, is presented on a Riemannian manifold of Hermitian positive-definite matrix. This filter acts as a clutter suppression procedure in the detection framework of the algorithm proposed in this paper, and can improve the detection performance. The principle of detection is that if a location has enough dissimilarity from the Riemannian mean or median estimated by its neighboring locations, targets are supposed to appear at this location. Numerical experiments and real sea clutter data are given to demonstrate the effectiveness of the proposed target detection algorithm.

      PubDate: 2017-09-23T08:17:03Z
      DOI: 10.1016/j.ast.2017.07.042
      Issue No: Vol. 70 (2017)
       
  • An evaluation of the tip clearance effects on turbine efficiency for space
           
    • Authors: Luiz Henrique Lindquist Whitacker; Jesuino Takachi Tomita; Cleverson Bringhenti
      Pages: 55 - 65
      Abstract: Publication date: November 2017
      Source:Aerospace Science and Technology, Volume 70
      Author(s): Luiz Henrique Lindquist Whitacker, Jesuino Takachi Tomita, Cleverson Bringhenti
      Large launch vehicles use their propulsion systems based on Liquid Rocket Engines (LRE) equipped with turbopumps. Turbopumps are complex rotary machines that supply high power, mass flow, and pressures in the engine system to reach the thrust requirements as determined in the rocket engine thermodynamic cycle. Strong engines need a secondary turbopump system called a booster. These boosters have pumps and turbines smaller than those of the main engine turbopumps, and their important function is to increase the fluid pressure at the inlet of the main turbopumps, mainly to avoid cavitation. In the present work, the influence of the tip clearance issues in an axial turbine installed to operate as oxidizer booster in the Space Shuttle Main Engine (SSME) were evaluated numerically. The results are compared with experimental data from National Aeronautics and Space Administration (NASA). The flow characteristics and the variation in the turbine efficiency for different jet velocities were determined for three different tip clearance values associated with the percentage of turbine blade height: 3.0%, 5.5%, and 8.0%. The turbine design, numerical issues, mesh generation and results are described and discussed. The methodology and numerical simulations used in the present work was consistent with the experimental data and can be extended for other correlated numerical simulations related to axial hydraulic turbines.

      PubDate: 2017-09-23T08:17:03Z
      DOI: 10.1016/j.ast.2017.07.038
      Issue No: Vol. 70 (2017)
       
  • Ionospheric delay prediction and code-carrier divergence testing for GBAS
           using neural network and GPS L1
    • Authors: Irfan Sayim; Haoxiang Lang; Dan Zhang
      Pages: 66 - 75
      Abstract: Publication date: November 2017
      Source:Aerospace Science and Technology, Volume 70
      Author(s): Irfan Sayim, Haoxiang Lang, Dan Zhang
      This paper presents a Neural Network (NN) model for predicting Ionospheric Delay (ID) which is used particularly in the Ground Based Augmentation System (GBAS) as a new and alternative approach. It is vital to have positioning solutions exhibiting high levels of performance in terms of navigation for aircraft to counter systematic errors in broadcast correction ranging measurements associated with GBAS, such as ID when using a Global Positioning System (GPS) L1 frequency receiver. In principle, ID can be simply estimated with the aid of dual frequency receivers (GPS L1 and L2) or a new GPS signal (L5). However, the GBAS relies only on the L1 frequency as the L2 frequency is not protected by Aeronautical Radio Navigation Service (ARNS) and L5 is not fully functional. In this context, the NN model is proposed to predict the ID from only GPS L1 pseudorange measurements. Benchmarking performed between prediction and conventional dual frequencies (GPS L1 and L2) illustrates the validity of the proposed method. In addition, divergence tests are performed to assess the effectiveness of predicted ID on the code-carrier. The possibility that ID type systematic and temporal errors in GBAS ranging measurements can be predicted accurately with only GPS L1 measurements is investigated. NN can also be used in the GBAS to reduce the code-carrier divergence effects between ground and airborne users.

      PubDate: 2017-09-23T08:17:03Z
      DOI: 10.1016/j.ast.2017.07.039
      Issue No: Vol. 70 (2017)
       
  • Novel adaptive surrogate model based on LRPIM for probabilistic analysis
           of turbine disc
    • Authors: Jianxing Mao; Dianyin Hu; Da Li; Rongqiao Wang; Jun Song
      Pages: 76 - 87
      Abstract: Publication date: November 2017
      Source:Aerospace Science and Technology, Volume 70
      Author(s): Jianxing Mao, Dianyin Hu, Da Li, Rongqiao Wang, Jun Song
      Probabilistic lifetime assessment for aero-engine turbine disc is required to ensure structural safety and reliability. For probabilistic analysis of aero-engine turbine disc, a large amount of random variables involving load, geometry, and material properties result in a high dimensional nonlinear state function for the fatigue lifetime, which can become prohibitively expensive. This paper presents a novel adaptive surrogate model for the probabilistic analysis of an aero-engine turbine disc by integrating the local radial point interpolation method (LRPIM) and directional sampling technique. The directional sampling technique includes initial sampling, limit state recognition and subsequent sampling. In order to implement the high-dimension-probabilistic analysis for the turbine disc, an adaptive scheme is proposed involving three parts, i.e. scale adjustment of local support domain, convergence test and repeated procedure of subsequent sampling. Applied to an aero-engine turbine disc probabilistic analysis problem with 11 dimensional random variables, it is demonstrated that the novel approach proposed improves the accuracy and computational efficiency with reduced sampling amount as compared to other models such as response surface method (RSM), Kriging model (KM) and artificial neural network model (ANNM). A leave-one-out (LOO) validation test is performed to verify the robustness of the prediction of the adaptive surrogate model in the probabilistic analysis process of aero-engine turbine discs.

      PubDate: 2017-09-23T08:17:03Z
      DOI: 10.1016/j.ast.2017.07.044
      Issue No: Vol. 70 (2017)
       
  • A modified elliptic integral method and its application in
           three-dimensional honeycombs
    • Authors: Ming-Hui Fu; Bin-Bin Zheng; Wei-Hua Li
      Pages: 88 - 94
      Abstract: Publication date: November 2017
      Source:Aerospace Science and Technology, Volume 70
      Author(s): Ming-Hui Fu, Bin-Bin Zheng, Wei-Hua Li
      In this paper, a modified elliptic integral method for the geometrically nonlinear analysis of Timoshenko beam is developed. Based on the elliptic integral method constructed by Sinclair, the proposed method also considers the axial, shearing and bending deformations of the beam, which makes up the deficiency of Sinclair's method without considering the shearing deformation at the fixed-end. In the geometrically nonlinear analysis of the three-dimensional honeycombs, the proposed method can be used to describe the unit cell as the elliptic integral equations, and the closed nonlinear equations can be obtained and solved by Newton iteration method. The numerical examples and three-point bending experiment indicate that, compared with Sinclair's method, the results obtained by the proposed method are in good agreement with those of the numerical simulation and experiment, especially for the beam with larger ratio of height to length. Therefore, the modified elliptic integral method developed in this paper has higher accuracy and wider range of application in the analysis of honeycombs.

      PubDate: 2017-09-23T08:17:03Z
      DOI: 10.1016/j.ast.2017.08.002
      Issue No: Vol. 70 (2017)
       
  • FDF-based combustion instability analysis for stabilization effects of a
           slotted plate in a multiple flame combustor
    • Authors: Seungtaek Oh; Hyunggeun Ji; Yongmo Kim
      Pages: 95 - 107
      Abstract: Publication date: November 2017
      Source:Aerospace Science and Technology, Volume 70
      Author(s): Seungtaek Oh, Hyunggeun Ji, Yongmo Kim
      In the present study, new promising methods are suggested to analyze thermoacoustic instability and the stabilization effects in the multiple flame combustor with a slotted plate. Using the generalized regression neural network (GRNN), the flame describing function (FDF) is effectively modeled from a limited number of experimental data. This neural-network based FDF method is able to generate more refined FDF data in an extended range. These refined FDF data are utilized in a Helmholtz solver for thermoacoustic instability analysis. According to the velocity perturbation ratio, eigenfrequencies are investigated to know the unstable regimes of the combustor. To take account of the effects of plate thickness, the present approach has slightly modified the Dowling method for modeling the impedance of a slotted plate. To find the effective damping conditions of a slotted plate, parametric studies have been carried out with the help of simulated annealing (SA) algorithm in wide-range operating conditions. It is identified that the absorption bandwidth becomes wider by decreasing slit width, and narrower width yields the higher average absorption coefficient. All the numerical results confirm that these new methodologies are quite reliable and widely applicable for the analysis of combustion instability encountered in many practical combustion systems.

      PubDate: 2017-09-23T08:17:03Z
      DOI: 10.1016/j.ast.2017.07.045
      Issue No: Vol. 70 (2017)
       
 
 
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