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Stage separation of recoverable liquid launch vehicle by using moving pulsating ball analogue for propellant sloshing

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Chinese Journal of Aeronautics 2024年第2期37卷 360-370页

作者： Yu LU Baozeng YUE Bailong HAO Bole MA Feng LIU Yuanyuan CHANG School of Aerospace Engineering Beijing Institute of TechnologyBeijing 100081China Beijing Institute of Astronautical Systems Engineering Beijing 100076China

In the process of stage separation of recoverable liquid launch vehicles,because of the large amount of residual fuel in the storage tanks,the influence of liquid sloshing on separation safety must be *** calculation simplicity and operation practicability,the Moving Pulsating Ball Model(MPBM)of large amplitude liquid sloshing is introduced into the calculation of launch vehicle stage *** the dynamic equation of the model with the energy relationship during"breathing movement",the formula calculating the force of liquid on the rigid body is *** with the calculations of commercial CFD calculation software,the accuracy of MPBM model is ***,all the external forces and moments are applied to the rigid body of the stages,so that the translational and rotational dynamic equations of the stages are obtained *** to the relative position of the two stages,the geometric shape of the interstage section and the engine of the second stage,the minimum clearance in the separation process can be decided to guarantee that the separation process is safe.

关键词： Moving Pulsating Ball Model(MPBM) Dynamics of stage separation Large amplitude sloshing Recoverable liquid launch vehicle Flight dynamics

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Interface reactions between TiAl alloys and diacetatozirconic acid-yttria molds differentiated by ammonium metatungstate addition

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Rare Metals 2023年第1期42卷 296-301页

作者： Yong-Shuang Cui De-Bo Liu Li-Hua Chai Zi-Yong Chen College of Materials Science and Engineering Beijing University of TechnologyBeijing100124China Beijing Institute of Astronautical Systems Engineering Beijing100076China

Two types of diacetatozirconic acid-yttria molds which were labeled as ZYW mold(diacetatozirconic acidyttria mold with traces of ammoium metatungstate in the slurry) and ZY mold(diacetatozirconic acid-yttria mold without ammonium metatungstate) were prepared by traditional investment *** ZYW and ZY molds were sintered in a carbon-reducing atmosphere and in air,respectively,at 1550℃ for 4 *** between Ti-47Al-2Cr-2Nb(at%) alloys and the molds at 1650℃ for 30 min were *** microstructures of the metalmold interfaces and the presence of inclusions and oxygen contamination in the TiAl bulk alloy were analyzed,and the influences of ammonium metatungstate were *** results indicate that WO_(3)releases O into the TiAl melt,introducing tungsten metal into the alloy *** TiAl alloy ingots cast in the ZY molds had the fewest inclusions and the lowest oxygen contamination.

关键词： TiAl-based alloys Diacetatozirconic acidyttria molds Ammonium metatungstate Interactions

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Security-Enhanced Directional Modulation Based on Two-Dimensional M-WFRFT

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China Communications 2024年第5期21卷 229-248页

作者： Zhou Zhuang Luo Junshan Wang Shilian Xia Guojiang School of Electronic Science National University of Defense TechnologyChangsha 410073China Beijing Institute of Astronautical Systems Engineering Beijing 100076China

Directional modulation(DM)is one of the most promising secure communication ***,when the eavesdropper is co-located with the legitimate receiver,the conventional DM has the disadvantages of weak anti-scanning capability,anti-deciphering capability,and low secrecy *** response to these problems,we propose a twodimensional multi-term weighted fractional Fourier transform aided DM scheme,in which the legitimate receiver and the transmitter use different transform terms and transform orders to encrypt and decrypt the confidential *** order to further lower the probability of being deciphered by an eavesdropper,we use the subblock partition method to convert the one-dimensional modulated signal vector into a twodimensional signal matrix,increasing the confusion of the useful *** results demonstrate that the proposed DM scheme not only provides stronger anti-deciphering and anti-scanning capabilities but also improves the secrecy rate performance of the system.

关键词： bit error rate directional modulation phased array secrecy rate weighted fractional Fourier transform

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Experimental and numerical investigation on the gas leakage regime for ventilated tail cavity of an underwater vehicle

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Journal of Hydrodynamics 2023年第1期35卷 46-60页

作者： Xiao-bo Quan Shao-hua Cheng College of Shipbuilding Engineering Harbin Engineering UniversityHarbin150001China China Academy of Launch Vehicle Technology Beijing100076China Beijing Institute of Astronautical Systems Engineering Beijing100076China

The objective of this paper is mainly to investigate the ventilated tail cavity flow of an underwater vehicle with focus on the gas leakage regime by experimental and numerical methods.A high-speed camera and pressure measurement system are used to record the cavity flow patterns and pressure behavior,*** numerical simulation is carried out with volume of fluid(VOF)model and Filter-based turbulence model(FBM).Good agreement can be obtained between the experimental and numerical *** are three gas leakage types in the evolution of the intact tail cavity,i.e.,twin-vortex tube entrainment(TVTE),toroidal vortex shedding(TVS)and hybrid twin-vortex tube entrainment and toroidal vortex shedding(TVTE-TVS).With the increase of Fr,the unsteady behavior of the cavity with different gas leakage types becomes more *** internal flow characteristics revealed three distinct regions including the ventilation influence region,the reverse flow region and the high shear flow region and have an important effect on the transition of gas leakage regime.

关键词： Ventilated tail cavity gas leakage regime unsteady behavior internal flow characteristics

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Research on algorithms of the astronautic data acquisition and encoder system based on domestic FPGA and SAD8309 3

Research on algorithms of the astronautic data acquisition a...

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3rd International Conference on Electronic Information engineering, Big Data, and Computer technology, EIBDCT 2024

作者： Zhou, Tianyi Huang, Hongjia Lv, Dun Wang, Xin Bian, Xu Dong, Wentai Wu, Jiayi Beijing Institute of Astronautical Systems Engineering China Academy of Launch Vehicle Technology Beijing China

ISBN: (纸本)9781510680449

Application verification is a key basic task for ensuring component independence. It involves a series of tests, assessments, and comprehensive evaluations of components before they are applied to equipment, to determine the maturity of component development and their suitability for usage. This paper introduces the component application verification work based on the astronautic data acquisition and encoder system, achieving 100% domestication of components and completing two key technological breakthroughs and innovations. The first is a design of an image compression algorithm scheme and an employment of H.264 image compression algorithm, using domestic FPGA to replace the original imported FPGA+DSP scheme. The second is an optimization of the acquisition and encoder precision algorithm, completing filter function based on domestic FPGA. After verification, the image compression effect of the FPGA is better than that of imported products. The statistical compressed image peak signal-to-noise ratio is greater than 30dB, meeting the requirements for usage. © COPYRIGHT SPIE. Downloading of the abstract is permitted for personal use only.

关键词： Field programmable gate arrays (FPGA)

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Microstructure,mechanical and fracture properties of friction stir welded 2195 Al-Li alloy joints

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Chinese Journal of Aeronautics 2024年第1期37卷 345-361页

作者： Guangda SUN Weizhao SUN Li ZHOU Sanfeng LUO Zili ZHANG Debo LIU Huiqiang WU State Key Laboratory of Advanced Welding and Joining Harbin Institute of TechnologyHarbin 150001China Shandong Provincial Key Laboratory of Special Welding Technology Harbin Institute of Technology(Weihai)Weihai 264209China Beijing Institute of Astronautical Systems Engineering Beijing 100076China

The 8 mm-thick 2195 Al-Li alloy joints were achieved by Friction Stir Welding(FSW).The microstructural evolution,temperature-dependent mechanical properties,and fracture properties were *** T1,δ’/β’and θ’precipitates were observed in the Base Metal(BM)and the Heat Affected Zone(HAZ).Most of the precipitates,except for re-precipitated δ’/β’phases,were dissolved in the Nugget Zone(NZ).The tensile specimens that failed at cryogenic temperatures(-196℃)had the maximum Ultimate Tensile Strength(UTS),and the fracture surface showed the inter-granular fracture *** to those at room temperature(25℃),the decreasing tensile properties at high temperature(180℃)were related to microstructure and strain hardening *** NZ presented the optimal fracture toughness,and the Crack Tip Opening Displacement(CTOD)was mutually dominated by microhardness and grain *** on Fatigue Crack Growth(FCG)rates indicates that the Thermal-Mechanically Affected Zone(TMAZ)exhibited the most superior fatigue resistance performance at stress intensity range below17 MPa.m1/2due to compressive residual stress and the crack closure *** fatigue fracture surfaces reveal that the crack propagation zone was characterized by the striations and secondary ***,inter-granular fracture behavior was responsible for the fastest FCG rates in the NZ.

关键词： Aluminum alloys Friction stir welding Microstructural evolution Mechanical properties Fracture mechanism

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Research on Retina-like Scanning Imaging Based on MEMS Mirror

Research on Retina-like Scanning Imaging Based on MEMS Mirro...

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2024 Photonics and Electromagnetics Research Symposium, PIERS 2024

作者： Liang, Long Wang, Hui Cao, Jie Hao, Qun Li, Yang Liang, Yaohui Beijing Institute of Technology China Beijing Institute of Astronautical Systems Engineering China Changchun University of Science and Technology China

ISBN: (纸本)9798350375909

Laser 3D imaging systems with high accuracy and strong anti-interference ability can sense the three-dimensional information of targets, widely used in fields such as urban modeling, automatic driving, low-altitude patrols, military aerospace, and more. According to the imaging method, traditional laser 3D imaging can be divided into scanning and non-scanning. However, both of two imaging modes mentioned face a trade-off between resolution and imaging efficiency. For example, the redundant information of scanning devices (such as galvanometer, rotating mirror, etal.) with fixed resolution scanning cause low imaging efficiency, and the resolution of non-scanning system is limited by large array of photodetectors which is difficult to process. To overcome this challenge and achieve high resolution and fast imaging efficiency, we propose a 3D imaging method based on MEMS mirror to implement retina-like scanning. On account of MEMS mirror has the characteristics of small size, fast scanning speed and high resolution. And the retina-like sampling method of spatial variable resolution has the advantages of large FOV and redundant information compression. By controlling the MEMS mirror to run retina-like scanning, the system can realize variable resolution scanning imaging of the target scene, and obtain three-dimensional images with high resolution in the central region and lower resolution in the periphery. The imaging efficiency is improved on the premise of ensuring the resolution. This approach effectively compresses redundant data, striking a balance between imaging efficiency and resolution, thus providing technical support for the development of high-performance laser 3D imaging technology. © 2024 IEEE.

关键词： Microchannels

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Clustering-Assisted Preselection Multiobjective Optimization for Equipment Portfolio 24

Clustering-Assisted Preselection Multiobjective Optimization...

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8th International Conference on Control engineering and Artificial Intelligence, CCEAI 2024

作者： Wang, Ningning Liu, Tingrui Gao, Xiangzhou Song, Shenmin Center for Control Theory and Guidance Technology Harbin Institute of Technology China Beijing Institute of Astronautical Systems Engineering China

ISBN: (纸本)9798400707971

The optimization of equipment system combination is crucial for the pre-deployment decision-making of our military. In order to obtain advantageous equipment portfolio solutions, we establish a multi-layer network optimization model for equipment systems and introduce a novel multi-objective optimization algorithm for equipment portfolios in combat systems. Firstly, a multi-objective optimization model for equipment system combination recommendation is established, with the objective of optimizing combat network redundancy and vulnerability. Secondly, due to the complexity of the equipment system optimization model and the challenge of finding optimal equipment portfolios, we propose a clustering-assisted preselection multi-objective evolutionary algorithm called MECAP. This algorithm is designed to enhance the convergence of the population towards the optimal solution set. Additionally, the experimental results highlight the benefits of applying MECAP for offspring generation strategy after model sampling. © 2024 ACM.

关键词： Decision making

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Game-theoretic private blockchain design in edge computing networks

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Digital Communications and Networks 2024年第6期10卷 1622-1634页

作者： Daoqi Han Yang Liu Fangwei Zhang Yueming Lu Key Laboratory of Trustworthy Distributed Computing and Service Ministry of EducationBeijing University of Posts and Telecommunications(BUPT)Beijing 100876China Beijing Institute of Astronautical Systems Engineering BeijingChina Beijing Institute of Technology BeijingChina

Considering the privacy challenges of secure storage and controlled flow,there is an urgent need to realize a decentralized ecosystem of private blockchain for cyberspace.A collaboration dilemma arises when the participants are self-interested and lack feedback of complete *** blockchains have similar faults,such as trustlessness,single-factor consensus,and heavily distributed ledger,preventing them from adapting to the heterogeneous and resource-constrained Internet of *** this paper,we develop the game-theoretic design of a two-sided rating with complete information feedback to stimulate collaborations for private *** design consists of an evolution strategy of the decision-making network and a computing power network for continuously verifiable *** formulate the optimum rating and resource scheduling problems as two-stage iterative games between participants and *** theoretically prove that the Stackelberg equilibrium exists and the group evolution is ***,we propose a multi-stage evolution consensus with feedback on a block-accounting workload for metadata *** continuously validate a block,the metadata of the optimum rating,privacy,and proofs are extracted to store on a lightweight ***,to increase resource utilization,surplus computing power is scheduled flexibly to enhance security by ***,the evaluation results show the validity and efficiency of our model,thereby solving the collaboration dilemma in the private blockchain.

关键词： Ecosystem Edge computing Feedback Stackelberg game Private blockchain Scalable computing power

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Derivation and validation of a similarity law for free-flight wind tunnel tests of parallel stage separation

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Chinese Journal of Aeronautics 2023年第8期36卷 91-100页

作者： Zhiming CHEN Fei XUE Haichuan YU Yuchao WANG Zenghui JIANG Wei LU Lei DONG China Academy of Aerospace Aerodynamics Beijing 100074China Beijing Institute of Astronautical Systems Engineering Beijing 100076China China Academy of Launch Vehicle Technology Beijing 100076China

Aiming at the safety problem of the stage separation of parallel reusable high-speed air vehicles,this paper studies the unsteady test method and focuses on deriving a similarity law of parallel stage separation free-flight wind tunnel *** new similarity law considers the influences of aerodynamic force and gravity on the motions of the two stages,as well as the influence of aerodynamic interference between the two stages on each other’s *** the perspective of multiangle physical equations,the conditions to ensure that the two-stage separation trajectory of a wind tunnel test is similar to that of a real air vehicle are derived innovatively,so as to ensure the authenticity and credibility of wind tunnel test *** similarity law is verified by an HIFiRE-5 air vehicle,and the separation trajectories of wind tunnel tests and the real air vehicle are obtained by numerical *** research shows that the similarity law derived in this paper can ensure that wind tunnel free-flight tests have the ability to predict the two-stage separation characteristics of real parallel *** analyzing the separation trajectory curve of the typical state,it is found that the new method can ensure that the trajectory error of a wind tunnel test does not exceed 1%,which indicates that this method is *** establishment of the new method lays the foundation for subsequent wind tunnel tests and provides support for research on the safety of the stage separation of parallel reusable air vehicles.

关键词： Droptesting in wind tunnel Free-flight wind tunnel test Multi-body separation Parallel stage separation Similaritylaw

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