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    A TDOA/FDOA cooperative localization method for multiple disjoint sources based on weighted multidimensional scaling analysis
    Ding WANG, Jiexin YIN, Xinguang ZHANG, Na’e ZHENG
    ACTA AERONAUTICAET ASTRONAUTICA SINICA    2023, 44 (7): 327105-327105.   DOI: 10.7527/S1000-6893.2022.27105
    Abstract2091)   HTML11)    PDF(pc) (4502KB)(520)       Save

    TDOA/FDOA localization is an important wireless positioning mechanism for moving emitters, and its location accuracy is greatly affected by measurement errors of TDOA/FDOA and prior measurement errors of sensor models (including sensor position and velocity). To improve the localization performance under the condition of high-level measurement errors, a TDOA/FDOA cooperative localization method for multiple disjoint sources is proposed based on weighted multidimensional scaling analysis in this paper. The proposed method consists of two calculation stages: Stage-a and Stage-b. Specifically, in Stage-a, two groups of scalar product matrices in multidimensional scaling analysis are employed to form the positioning relationship, which is further used to yield the solutions for the locations of multiple disjoint sources and sensors by constructing a weighting matrix. In Stage-b, a constrained minimization model is established based on the intermediate variables introduced in multidimensional scaling analysis to determine the estimation errors in Stage-a. By solving this optimization problem, the expression for the localization errors in Stage-a are obtained, so as to refine the position and velocity estimates of the multiple disjoint sources as well as the sensors. In addition, the first-order error analysis is employed to prove that the proposed method can asymptotically reach the Cramér-Rao Bound (CRB) accuracy. Simulation results show that the new method outperforms the existing TDOA/FDOA positioning methods.

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    Real⁃time dense small object detection algorithm for UAV based on improved YOLOv5
    Zhiqiang FENG, Zhijun XIE, Zhengwei BAO, Kewei CHEN
    ACTA AERONAUTICAET ASTRONAUTICA SINICA    2023, 44 (7): 327106-327106.   DOI: 10.7527/S1000-6893.2022.27106
    Abstract1255)   HTML44)    PDF(pc) (5498KB)(344)       Save

    UAV aerial images have more complex backgrounds and a large number of dense small targets compared with natural scene images, which impose higher requirements on the detection network. On the premise of ensuring real-time object detection, a YOLOv5-based UAV real-time dense small object detection algorithm is proposed for the problem of low accuracy of dense small object detection in UAV view. First, combining Spatial Attention Module (SAM) with Channel Attention Module (CAM), the fully connected layer after feature compression in CAM is improved to reduce the computational effort. In addition, the connection structure of CAM and SAM is changed to improve the spatial dimensional feature capture capability. In summary, a Spatial-Channel Attention Module (SCAM) is proposed to improve the model's attention to the aggregated regions of small targets in the feature map; secondly, an SCAM- based Attentional Feature Fusion module (SC-AFF) is proposed to enhance the feature fusion efficiency of small targets by adaptively assigning attentional weights according to feature maps of different scales; finally, a backbone network is introduced in the Transformer in the backbone network, and use the SC-AFF to improve the feature fusion at the original residual connections to better capture global information and rich contextual information, and improve the feature extraction capability of dense small targets in complex backgrounds. Experiments are conducted on the VisDrone2021 dataset. The effects of different network scale parameters and different input resolutions on the detection accuracy and speed of YOLOv5 are first investigated. The analysis concludes that YOLOv5s is more suitable to be used as a benchmark model for UAV real-time object detection. Under the benchmark of YOLOv5s, the improved model improves mAP50 by 6.4% and mAP75 by 5.8%, and the FPS for high-resolution images can reach 46. The mAP50 of the model trained at an input resolution of 1504×1504 can reach 54.5%, which is 11.5% better than that of YOLOv4. The accuracy is improved while the detection speed FPS remains at 46, which is more suitable for real-time UAV object detection in dense small target scenarios.

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    Technology development of high temperature superconducting machine for electric aviation
    Dongbin SONG, Juzhuang YAN, Wenjiang YANG, Mingliang BAI, Rujing LIU, Shaopeng WANG, Yu LIU, Aimei TIAN
    ACTA AERONAUTICAET ASTRONAUTICA SINICA    2023, 44 (9): 27469-027469.   DOI: 10.7527/S1000-6893.2022.27469
    Abstract1177)   HTML41)    PDF(pc) (9270KB)(331)       Save

    The superconducting machine has prospects of a wide range of applications in aviation electric propulsion due to its advantages such as small size, high power density, and high efficiency. The characteristics and current situation of the superconducting pure/hybrid electric drive systems are compared, showing the importance of the superconducting machine for high power aviation electric propulsion. In view of different requirements for motors and generators for the superconducting electric drive system for high power aviation electric propulsion, the operating principles and structural topologies of those prototypes of High Temperature Superconducting (HTS) machines studied in the past are reviewed and classified, and the advantages and disadvantages are summarized and analyzed. On this basis, the key technologies of superconducting machine are outlined in terms of superconducting technology, AC superconducting armature, rotor technology, cryogenic technology and insulation technology. Under the background of aviation electrification, the progress in the application of superconducting electric drive system in aviation electric propulsion is outlined, and future development of superconducting electric aviation is also discussed.

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    Progress and application of key technologies of SensorCraft
    Shuai HAO, Tielin MA, Yi WANG, Jinwu XIANG, Hongzhong MA, Baifeng JIANG, Jun CAO
    ACTA AERONAUTICAET ASTRONAUTICA SINICA    2023, 44 (6): 27034-027034.   DOI: 10.7527/S1000-6893.2022.27034
    Abstract1146)   HTML89)    PDF(pc) (12633KB)(923)       Save

    SensorCraft is an early warning and surveillance and information synthesis aircraft proposed by the Air Force Research Laboratory, with high ceiling and long endurance. It adopts the platform-payload integration technology, with the dual features of the aircraft and sensor. Coupling of multiple elements between platform and payload means that the overall layout design is different from that of the traditional Intelligence, Surveillance and Reconnaissance (ISR) vehicle. Flight conditions and performance indexes bring new challenges to the aerodynamic design. Aeroelastic problem of large aspect ratio flexible wing not only worsens flight performance, but also leads to loss of electromagnetic performance of wing conformal antenna. This paper summarizes the technical characteristics of SensorCraft, expounds the development history of the United States SensorCraft system from two aspects of the flight platform and conformal antenna. From the perspective of technical characteristics, key technologies supporting SensorCraft are sorted out, such as integrated layout design, laminar drag reduction, gust alleviation, conformal antenna design, deformation measurement & reconstruction, and electromagnetic performance compensation. Relevant applications are introduced. The development trend of this aircraft is also discussed in terms of the flight ability, stealth ability, perception ability and coordination ability of the aircraft, so as to provide reference for the new ISR aircraft.

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    First flight of SpaceX heavy-lift starship: Enlightenment for aerospace industry in China
    Guang MENG, Chang LIU, Dongchun YANG, Chenghong ZHOU, Hua ZHOU
    ACTA AERONAUTICAET ASTRONAUTICA SINICA    2023, 44 (10): 28914-028914.   DOI: 10.7527/S1000-6893.2023.28914
    Abstract942)   HTML44)    PDF(pc) (7472KB)(400)       Save

    The development of reusable launch vehicles is the persistent pursuit of aerospace industry. Although the first flight of the fully reusable SpaceX two-stage heavy-lift starship was successfully launched, the starship was ultimately self-destructed due to the loss of control in the subsequent flight. After reviewing evolutionary design and the first flight experience of the heavy-lift starship, this paper analyzed the application modes of the heavy-lift starship based on the overall scheme, identified the key technologies involved, and summarized its impact on aerospace industry. Finally, the enlightenment and suggestions of the heavy-lift starship’s achievements to China’s aerospace industry are provided.

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    Internal leakage distribution model and parameter sensitivity analysis of spool valve couple at zero position
    Zhichuang CHEN, Shenghong GE, Zhuolei ZHANG, Yuchuan ZHU
    ACTA AERONAUTICAET ASTRONAUTICA SINICA    2023, 44 (6): 427004-427004.   DOI: 10.7527/S1000-6893.2022.27004
    Abstract838)   HTML12)    PDF(pc) (5608KB)(196)       Save

    Aiming at the uncertainty of internal leakage for spool valve couple at zero position effected by the size parameters perturbation, a mathematical model of internal leakage at zero position considering parameter perturbation is established. Then, the distribution characteristics of internal leakage at zero position under the perturbation of size parameters are obtained. Furthermore, a Kriging surrogate model of the mapping relationship between process parameters and distribution characteristic parameters of internal leakage at zero position is established. Based on the Kriging surrogate model, the global sensitivity analysis of distribution characteristic of internal leakage at zero position to process parameters is carried out by Sobol method, which can provide a theoretical support for reducing internal leakage and improving consistency. The results show that the internal leakage at zero position under the size parameters perturbation obeys normal distribution law. Influence of the interaction among process parameters on the distribution characteristics can be ignored. Compared with the axial size process parameters, distribution characteristics are more sensitive to the variation of radial size process parameters and throttling edge corner radius process parameters. Minimum radial clearance of spool valve couple has the greatest influence on the average value of internal leakage at zero position, while the maximum corner radius of throttle edge of spool has the greatest influence on the consistency of internal leakage at zero position. Experimental values of the internal leakage at zero position of spool valve couple present a certain fluctuation, which is consistent with the overall prediction trend of the theoretical model.

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    Research progress in combustion characteristics and engine applications of energetic hydrocarbon fuels
    Yushu JIN, Xu XU, Qingchun YANG
    ACTA AERONAUTICAET ASTRONAUTICA SINICA    2023, 44 (5): 26690-026690.   DOI: 10.7527/S1000-6893.2022.26690
    Abstract811)   HTML63)    PDF(pc) (2898KB)(617)       Save

    Adding energetic solid particles, such as aluminum and boron, into liquid hydrocarbon fuel is an effective approach to improve the energy characteristics of the fuel, and it is also an important technological base in improving the performance of rocket engine and ramjet in the future. In this paper, the development and current demand of energetic hydrocarbon fuels are introduced, and two types of energy-containing hydrocarbon fuels and their respective advantages are analyzed and compared. Besides, the single droplet combustion experiments of hydrocarbon fuel containing solid particles at home and abroad are reviewed. The characteristic combustion process and typical combustion phenomena of energy-containing hydrocarbon fuel droplets are introduced. In addition, the application progress of energetic hydrocarbon fuels in rocket engine, ramjet and scramjet are summarized. Finally, the future research of hydrocarbon fuels containing solid particles is prospected.

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    Research on All-Domain Fire Field in Future Air Combat
    Acta Aeronautica et Astronautica Sinica    DOI: 10.7527/S1000-6893.2023.29699
    Accepted: 13 October 2023

    Technology development in high pressure compressor of civil high bypass-ratio turbofan engine
    Chuanjun CAO, Tianyi LIU, Wei ZHU, Jinchun WANG
    ACTA AERONAUTICAET ASTRONAUTICA SINICA    2023, 44 (12): 27824-027824.   DOI: 10.7527/S1000-6893.2022.27824
    Abstract731)   HTML67)    PDF(pc) (6001KB)(552)       Save

    The high bypass-ratio turbofan engines are chosen invariably to provide power and thrust for large passenger aircraft. The vigorous development of the international civil aviation market has promoted the rapid improvement of civil high bypass-ratio turbofan engine technology. As the core component of aero-engines, the high-pressure compressor has the “three highs” characteristics, high efficiency, high pressure ratio, and high mass flow. The American General Electric (GE) Company, Pratt & Whitney (PW) Company and the British Rolls-Royce (RR) Company remain international leading level in the high-pressure compressor design technology. In recent years, research and development concerning civil high bypass-ratio turbofan engine have been carried out based on two National Science and Technology Major Projects, i.e., the Large Airplane Major Project and the Aircraft Engine and Gas Turbine Major Project. Thus, some progress has been achieved in the area of high-pressure compressor design technology. In this paper, the technical features of the high-pressure compressor of civil high bypass-ratio turbofan engine were analyzed. And then, the research status and development trend of it at home and abroad were reviewed. Finally, the domestic technology difficulties and challenges were pointed out objectively. It is expected that learning from the characteristics of the international advanced design could enlighten the technology development of the high-pressure compressor of civil high bypass-ratio turbofan engine in China.

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    Key structural dynamic design technologies in liquid rocket engines: Review
    Dahua DU, Bin LI
    ACTA AERONAUTICAET ASTRONAUTICA SINICA    2023, 44 (10): 27554-027554.   DOI: 10.7527/S1000-6893.2022.27554
    Abstract714)   HTML74)    PDF(pc) (4813KB)(520)       Save

    With the development of liquid rocket engine technologies, structural dynamic problems become one of the key factors affecting the life and reliability of engines. In the past decades, the design concepts and methods of the engine gradually developed from the initial static strength and safety life design to the combination of dynamic and static strength, and economic life design, which were widely used in engines, significantly improving the working reliability of the engine structures. However, the increasing size and complex structure and the extreme harshness of the working environment for the new rocket engines require urgent solution to the technical problems of engine structural dynamic design to meet the needs of high performance, high reliability, light weight and reusability. This paper reviews the key technologies such as load prediction, dynamic modeling and model updating, dynamic strength assessment and life prediction, and anti-fatigue design on account of dynamics optimization, based on the analysis of typical dynamic problems in engine structures. The research summary and prospect are also presented. This review will provide guidance for the development of structural dynamic design technology of liquid rocket engines.

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    Theoretical analysis of performance of solid rocket scramjet
    Xiang ZHAO, Zhixun XIA, Chuanbo FANG, Likun MA, Chaolong LI, Yifan DUAN
    ACTA AERONAUTICAET ASTRONAUTICA SINICA    2023, 44 (5): 126971-126971.   DOI: 10.7527/S1000-6893.2022.26971
    Abstract711)   HTML17)    PDF(pc) (2754KB)(239)       Save

    Considering the dissociation of combustion products, this paper conducts research on modeling of the working process of the solid rocket scramjet using the Brayton cycle method. Then, the theoretical performance of the engine is analyzed, and the effects of flight parameters and fuel types on engine performance are studied. The flight envelope of scramjet engine is also discussed. The main conclusions are as follows. The performance of solid rocket scramjet decreases with the increase of flight Mach number and flight altitude. When the working equivalent ratio increases, the gravimetric impulse and volumetric impulse decrease, but the specific thrust increases gradually. When the working air-fuel ratio increases, the specific thrust decreases, but the gravimetric impulse and volumetric impulse increase gradually. In the range of air-fuel ratio from 5 to 27, the volumetric impulse of the engine fueled with solid propellant has obvious advantages, but the specific thrust and gravimetric impulse are inferior to the engine fueled with hydrogen and kerosene. Compared with that fueled with hydrogen and kerosene, the boron-based solid propellant scramjet can work in a wider range of Mach numbers, which indicates that the solid rocket scramjet has a potential of wide flight envelope.

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    Target round-up control for multi-agent systems based on reinforcement learning
    Zhilin FAN, Hongyong YANG, Yilin HAN
    Acta Aeronautica et Astronautica Sinica    2023, 44 (S1): 727487-727487.   DOI: 10.7527/S1000-6893.2022.27487
    Abstract699)   HTML15)    PDF(pc) (2067KB)(251)       Save

    A target round-up control method for multi-agent systems is proposed based on reinforcement learning. Firstly, Markov game modeling for multi-agent systems is carried out. The potential energy function which meets the requirements of arriving at the desired state and avoiding obstacles is designed according to the task of rounding up, and reinforcement learning principles are combined with the model control. The round-up is performed using multi-agent reinforcement learning guided by the potential energy model. Secondly, based on the existing potential energy model, two surrounding strategies are established: tracking round-up and circumnavigation round-up. With the first strategy, consistent tracking of multiple agents is achieved by designing the potential energy function of velocity. In the second strategy, virtual circumnavigation points are added to design potential energy functions, achieving desired circumnavigation. Finally, the effectiveness of the round-up control based on multi-agent reinforcement learning is verified by simulation.

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    Uncertainty⁃based design system for aeroengines
    Xinqian ZHENG, Junying WANG, Weina HUANG, Yu FU, Ronghui CHENG, Hongyang XIONG
    ACTA AERONAUTICAET ASTRONAUTICA SINICA    2023, 44 (7): 27099-027099.   DOI: 10.7527/S1000-6893.2022.27099
    Abstract698)   HTML44)    PDF(pc) (3949KB)(403)       Save

    A significant number of random and epistemic uncertainties exist in the whole life cycle of an aeroengine, causing problems such as a long design iteration cycle, low manufacturing qualification rate, and difficulties in maintenance. Recent years have witnessed a series of research on uncertainty analysis at home and abroad; however, the uncertainty design system of aeroengines has not been proposed systematically at the theoretical level. Based on the current deterministic design system and the results of uncertainty research, this paper discusses the construction of the uncertainty-based design system and realization of the design system reform for aeroengines. The uncertainty factors and their influence on aeroengines are first summarized, followed by discussion of the definition and necessity of the uncertainty-based design system. The ultimate goal of the uncertainty-based design system is to achieve successful research and development with a single iteration. The performance distribution is quantitatively evaluated and controlled at each design stage to produce a comprehensive optimal design scheme in terms of performance, reliability, robustness, and costs in the whole life cycle. Based on this definition, the basic elements of the uncertainty-based design system are analyzed, including the process, method, platform, specification, and organization. Finally, the periodic prospects, expected benefits, and challenges of the uncertainty-based design system are presented.

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    Novel multi-fidelity surrogate model assisted many-objective optimization method
    Huan ZHAO, Zhenghong GAO, Lu XIA
    ACTA AERONAUTICAET ASTRONAUTICA SINICA    2023, 44 (6): 126962-126962.   DOI: 10.7527/S1000-6893.2022.26962
    Abstract690)   HTML38)    PDF(pc) (5834KB)(488)       Save

    Compared with a conventional helicopter, a compound helicopter with its rigid coaxial rotor, famous as an Advancing Blade Concept (ABC) rotor, has more stringent requirements for the aerodynamic performance of the rotor airfoil. And the 10 more index requirements, e.g., the low-drag and high drag-divergence characteristics at higher Mach numbers, the high lift-drag characteristics at medium and low Mach numbers, and good pitching moment characteristics at all conditions, face the problem of many-objective optimization. To solve this issue, this paper first develops a novel nonlinear dimension-reduction technology based on Kernel Principal Component Analysis (KPCA), then establishes an efficient many-objective robust optimization framework based on a novel Adaptive Multi-Fidelity Polynomial Chaos-Kriging (AMF-PCK) surrogate model. Moreover, the paper proposes a Variable-Fidelity Pseudo Expected Improvement Matrix (VF-PEIM) parallel in-filling method, which significantly improves the efficiency and ability of many-objective optimization. The novel AMF-PCK assisted multi-objective optimization method is used to optimize the 7% thickness rotor airfoil of such compound helicopter. The aerodynamic performances of the designed airfoils are compared with those of the classical OA407 airfoil at high, medium, and low Mach numbers comprehensively. Results demonstrate the effectiveness of the proposed many-objective global optimization method and a significant improvement of high-speed aerodynamic characteristics of the designed rotor airfoils.

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    Review of key technologies for fault diagnosis and accommodation for multi⁃electric distributed engine control system
    Wanli ZHAO, Yingqing GUO, Kejie XU, Cansen WANG, Haojie YING, Xinxin TAO
    ACTA AERONAUTICAET ASTRONAUTICA SINICA    2023, 44 (10): 27519-027519.   DOI: 10.7527/S1000-6893.2022.27519
    Abstract687)   HTML36)    PDF(pc) (4677KB)(401)       Save

    In view of the demand for future aero-engines,combined with the characteristics and advantages of multi electric distributed control,the key technologies of fault diagnosis and accommodation of multi-electric distributed engine control system are studied based on advanced algorithms. Firstly,this paper summarizes the fault diagnosis and accommodation technology of multi-electric distributed engine control system at home and abroad from four aspects:distributed engine control system,more electric engine,fault diagnosis and fault-tolerant control methods and hardware in the loop simulation platform,and points out the key problems of fault diagnosis and accommodation of multi-electric distributed engine control system at present. Then the key technologies are proposed,which are the design of fault diagnosis and accommodation architecture of multi-electric distributed engine control system,the model-based fault diagnosis and fault-tolerant control method,the fault diagnosis and accommodation scheme of dual active redundant motor control system,the electro-mechanical actuator fault diagnosis and accommodation scheme based on deep learning,and the construction of hardware in the loop simulation platform. Finally,the future development trend of fault diagnosis and fault tolerance of aeroengine multi electric distributed control system is prospected.

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    Maneuvering decision-making of multi-UAV attack-defence confrontation based on PER-MATD3
    Xiaowei FU, Zhe XU, Jindong ZHU, Nan WANG
    ACTA AERONAUTICAET ASTRONAUTICA SINICA    2023, 44 (7): 327083-327083.   DOI: 10.7527/S1000-6893.2022.27083
    Abstract662)   HTML17)    PDF(pc) (2920KB)(392)       Save

    This paper explores multi-UAVs attack-defence confrontation maneuvering decision-making in a complex environment with random distribution of obstacles. A motion model and a radar detection model for both attack and defence sides are constructed. the Twin Delayed Deep Deterministic policy gradient (TD3) algorithm is extended to the multi-agent field to solve the problem of overestimation of the value function in the Multi-Agent Deep Deterministic Policy Gradient (MADDPG) algorithm. To improve the learning efficiency of the algorithm, a Prioritized Experience Replay Multi-Agent Twin Delayed Deep Deterministic policy gradient (PER-MATD3) algorithm is proposed based on the priority experience playback mechanism. The simulation experiments show that the method proposed in this paper has a good confrontation effect in multi-UAV attack-defence confrontation maneuvering decision making, and the advantages of the PER-MATD3 algorithm over other algorithms in terms of convergence speed and stability are verified by comparison.

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    Mechanisms, algorithms, implementation and perspectives of brain⁃inspired navigation
    Xiangwei ZHU, Dan SHEN, Kai XIAO, Yuexin MA, Xiang LIAO, Fuqiang GU, Fangwen YU, Kefu GAO, Jingnan LIU
    Acta Aeronautica et Astronautica Sinica    2023, 44 (19): 28569-028569.   DOI: 10.7527/S1000-6893.2023.28569
    Abstract650)   HTML35)    PDF(pc) (9701KB)(536)       Save

    The rapid development of brain and neuroscience in recent decades has initially revealed the neural mechanism of animal navigation. Drawing on the brain neural structures and information processing mechanisms, the study of brain-inspired intelligent navigation systems provides new inspiration for low-power, highly robust autonomous intelligent navigation in complex environments. Based on a detailed review of the neural mechanisms of animal spatial navigation, this paper then outlines and discusses current intelligent algorithms for robotic bionic brain-inspired navigation, which can be categorized into three types according to the three types of neural networks used to process navigation information for intelligent navigation: attractor neural networks, deep reinforcement learning, and spiking neural networks. Then, the ways for implementing brain-inspired navigation, including bionic intelligent sensors and neuromorphic processor platforms, are sorted out. Finally, the development trend of brain-inspired navigation is discussed, including further exploration of the brain neural mechanism of navigation in the biological world and its information processing process with low energy consumption and high robustness mechanism, subcategorization of the conceptual connotation of brain-inspired navigation, and the ways to improve the evaluation index and the unified implementation framework.

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    Review on technology of bird detection with weather radar
    Weishi CHEN, Jia LIU, Qingbin WANG, Xianfeng LU, Jie ZHANG, Xiaolong CHEN, Yifeng HUANG
    ACTA AERONAUTICAET ASTRONAUTICA SINICA    2023, 44 (5): 26781-026781.   DOI: 10.7527/S1000-6893.2022.26781
    Abstract637)   HTML38)    PDF(pc) (6027KB)(325)       Save

    The weather radar network is especially suitable for observation of large-scale bird activities on the continent. This paper first introduces the relatively mature bird early warning systems based on the weather radar networks in the United States and Europe, and makes a comparative analysis of their performance. Then, the echo characteristics of the weather radar bird target are analyzed in terms of echo amplitude, altitude distribution, flight speed and direction, and then the bird information extraction technologies including clutter suppression, weather information elimination, bird target feature extraction, machine learning, and cross validation are discussed. On this basis, the applications of bird detection with the weather radar network in bird ecology research and bird strike avoidance are introduced. The preliminary idea of establishing a national bird surveillance system based on the weather radar network in China is discussed in terms of detection coverage and weather radar system performance.

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    Integrated aerodynamic and stealth optimization of aircraft based on NS/CFIE adjoint equations
    Jiangtao HUANG, Lin ZHOU, Xian CHEN, Chuang MA, Gang LIU, Zhenghong GAO
    ACTA AERONAUTICAET ASTRONAUTICA SINICA    2023, 44 (12): 127757-127757.   DOI: 10.7527/S1000-6893.2022.27757
    Abstract626)   HTML6)    PDF(pc) (5034KB)(269)       Save

    Advanced integrated aerodynamic and stealth design technology is the key link to realize the technical indexes of future combat aircraft, such as high stealth, high maneuverability, wide speed range and long range. This study derives the “coupled” adjoint equation of aerodynamic stealth based on the idea of interdisciplinary coupling adjoint. First, the adjoint equation of the flow field is constructed based on the Navier-Stokes equation. Through the variational processing of near-field vector multiplication, far-field vector multiplication, and the radar scattering area, the adjoint equation based on MLFMA is then developed. The electromagnetic adjoint equation of the algorithm, combined with the independently developed XSQP optimization framework and parametric modeling technology, constructs a highly reliable aerodynamic stealth comprehensive optimization technology platform. Taking a certain flying wing layout as the research object, we conduct the aerodynamic stealth integration test. The test results show that both the gradient calculation accuracy of the established accompanying platform and the optimization design efficiency are high, providing strong technical support for the aerodynamic stealth integration design of combat aircraft.

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    General planning method for energy optimal flight path of solar⁃powered aircraft in near space
    Xianzhong GAO, Xiaolong DENG, Yujie WANG, Zheng GUO, Zhongxi HOU
    ACTA AERONAUTICAET ASTRONAUTICA SINICA    2023, 44 (8): 27265-027265.   DOI: 10.7527/S1000-6893.2022.27265
    Abstract620)   HTML36)    PDF(pc) (8136KB)(315)       Save

    Solar-powered aircraft is one of the most promising technical route for the development of low-speed aerial vehicle in near space, and is expected to be an ideal platform for regional communication, relay and transportation.N×24-hour energy closed loop is the crucial problem for the development of near space solar-powered aircraft,and is also a key technology for aircraft to have the ability of “regional maintenance & time sustainability”. The energy optimal flight path planning method is an effective technical route to solve the problem of day-night energy closed-loop of solar-powered aircraft in near space. Currently, there are two methods for energy optimal flight path planning: one is the method without considering the change of wind field, and the other is the method without considering the change of large-scale altitude. Analysis and comment are given to the research results of these two methods. In order to conquer the difficulties and challenges brought by these two different processing frameworks in practical engineering application, suggestion is proposed to build a uniform framework based on reinforcement learning to form a “general” flight path planning method. This framework should consider the changes of solar radiation, space altitude and wind field, and also the effects of energy stored by gravity potential and energy harvested from wind shear. The key technologies to achieve this aim are analyzed: The environmental characterization and reconstruction of wind field; the impact of near space gradient wind field on the energy of solar aircraft glide trajectory; The generation and classification of optimal flight path demonstration trajectory; the construction of solar aircraft reinforcement learning framework based on demonstration trajectory. This paper provides theoretical support for the design method of energy optimal flight path planning, and technical support for realization of high-altitude long-endurance flight.

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