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A physics-informed deep learning framework for spacecraft pursuit-evasion task assessment

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Chinese Journal of Aeronautics 2024年第5期37卷 363-376页

作者： Fuyunxiang yang Leping yang Yanwei zhu College of Aerospace Science and Engineering National University of Defense TechnologyChangsha 410073China

Qualitative spacecraft pursuit-evasion problem which focuses on feasibility is rarely studied because of high-dimensional dynamics,intractable terminal constraints and heavy computational *** this paper,A physics-informed framework is proposed for the problem,providing an intuitive method for spacecraft threat relationship determination,situation assessment,mission feasibility analysis and orbital game rules *** the first time,situation adjustment suggestions can be provided for the weak player in orbital ***,a dimension-reduction dynamics is derived in the line-of-sight rotation coordinate system and the qualitative model is determined,reducing complexity and avoiding the difficulty of target set presentation caused by individual ***,the Backwards Reachable Set(BRS)of the target set is used for state space partition and capture zone ***-time analysis can eliminate the influence of changeable initial state and enable the proposed framework to analyze plural situations ***,a time-dependent Hamilton-Jacobi-Isaacs(HJI)Partial Differential Equation(PDE)is established to describe BRS evolution driven by dimension-reduction dynamics,based on level set ***,Physics-Informed Neural Networks(PINNs)are extended to HJI PDE final value problem,supporting orbital game rules summarization through capture zone evolution ***,numerical results demonstrate the feasibility and efficiency of the proposed framework.

关键词： Spacecraft pursuit-evasion Qualitative differential game Physics-Informed Neural Networks(PINNs) Reachability analysis Hamilton-Jacobi-Isaacs(HJI) Partial Differential Equations(PDEs)

Smoothed particle hydrodynamics based numerical study of hydroplaning considering permeability characteristics of runway surface

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Frontiers of Structural and Civil Engineering 2024年第3期18卷 319-333页

作者： yang yang Xingyi zhu Denis JELAGIN Alvaro GUARIN Key Laboratory of Road and Traffic Engineering of Ministry of Education Tongji UniversityShanghai 200092China Auto Engineering Research Institute BYD Auto Industry Company LimitedShenzhen 518118China Department of Civil and Architectural Engineering KTH Royal Institute of TechnologyStockholm 10044Sweden

The presence of water films on a runway surface presents a risk to the landing of *** tire of the aircraft is separated from the runway due to a hydrodynamic force exerted through the water film,a phenomenon called *** a lot of numerical investigations into hydroplaning have been conducted,only a few have considered the impact of the runway ***,computational problems,such as excessive distortion and computing efficiency decay,may arise with such numerical models when dealing with the thin water *** paper presents a numerical model comprising of the tire,water film,and the interaction with the runway,applying a mathematical model using the smoothed particle hydrodynamics and finite element(SPH-FE)*** material properties and geometric features of the tire model were included in the model framework and water film thicknesses from 0.75 mm to 7.5 mm were used in the numerical ***,this work investigated the impacts of both surface texture and the runway *** interaction between tire rubber and the rough runway was analyzed in terms of frictional force between the two *** SPH-FE model was validated with an empirical equation proposed by the National Aeronautics and Space Administration(NASA).Then the computational efficiency of the model was compared with the traditional coupled Eulerian-Lagrangian(CEL)*** on the SPH-FE model,four types of the runway(Flat,SMA-13,AC-13,and OGFC-13)were *** simulation of the asphalt runway shows that the SMA-13,AC-13,and OGFC-13 do not present a hydroplaning risk when the runway permeability coefficient exceeds 6%.

关键词： SPH-FE approach hydroplaning numerical simulation surface texture runway surface reconstruction

Bound-Preserving Discontinuous Galerkin Methods with Modified Patankar Time Integrations for Chemical Reacting Flows

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Communications on Applied Mathematics and Computation 2024年第1期6卷 190-217页

作者： Fangyao zhu Juntao Huang yang yang Department of Mathematical Sciences Michigan Technological UniversityHoughtonMI49931USA Department of Mathematics and Statistics Texas Tech UniversityLubbockTX79409USA

In this paper,we develop bound-preserving discontinuous Galerkin(DG)methods for chemical reactive *** are several difficulties in constructing suitable numerical *** of all,the density and internal energy are positive,and the mass fraction of each species is between 0 and ***,due to the rapid reaction rate,the system may contain stiff sources,and the strong-stability-preserving explicit Runge-Kutta method may result in limited time-step *** obtain physically relevant numerical approximations,we apply the bound-preserving technique to the DG *** traditional positivity-preserving techniques can successfully yield positive density,internal energy,and mass fractions,they may not enforce the upper bound 1 of the mass *** solve this problem,we need to(i)make sure the numerical fluxes in the equations of the mass fractions are consistent with that in the equation of the density;(ii)choose conservative time integrations,such that the summation of the mass fractions is *** the above two conditions,the positive mass fractions have summation 1,and then,they are all between 0 and *** time discretization,we apply the modified Runge-Kutta/multi-step Patankar methods,which are explicit for the flux while implicit for the *** methods can handle stiff sources with relatively large time steps,preserve the positivity of the target variables,and keep the summation of the mass fractions to be ***,it is not straightforward to combine the bound-preserving DG methods and the Patankar time *** positivity-preserving technique for DG methods requires positive numerical approximations at the cell interfaces,while Patankar methods can keep the positivity of the pre-selected point values of the target *** match the degree of freedom,we use polynomials on rectangular meshes for problems in two space *** evolve in time,we first read the polynomials at the Gaussian ***,suitable slope l

关键词： Compressible Euler equations Chemical reacting flows Bound-preserving Discontinuous Galerkin(DG)method Modified Patankar method

A Support Data-Based Core-Set Selection Method for Signal Recognition

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China Communications 2024年第4期21卷 151-162页

作者： yang Ying zhu Lidong Cao Changjie National Key Laboratory of Wireless Communications(University of Electronic Science and Technology of China) Chengdu 611731China College of Computer Science and Cyber Security(Chengdu University of Technology) Chengdu 610059China College of Mathmatics and Physics(Chengdu University of Technology) Chengdu 610059China

In recent years,deep learning-based signal recognition technology has gained attention and emerged as an important approach for safeguarding the electromagnetic ***,training deep learning-based classifiers on large signal datasets with redundant samples requires significant memory and high *** paper proposes a support databased core-set selection method(SD)for signal recognition,aiming to screen a representative subset that approximates the large signal ***,this subset can be identified by employing the labeled information during the early stages of model training,as some training samples are labeled as supporting data *** support data is crucial for model training and can be found using a border sample *** results demonstrate that the SD method minimizes the impact on model recognition performance while reducing the dataset size,and outperforms five other state-of-the-art core-set selection methods when the fraction of training sample kept is less than or equal to 0.3 on the RML2016.04C dataset or 0.5 on the RML22 *** SD method is particularly helpful for signal recognition tasks with limited memory and computing resources.

关键词： core-set selection deep learning model training signal recognition support data

IMAGE SUPER-RESOLUTION RECONSTRUCTION BY HUBER REGULARIZATION AND TAILORED FINITE POINT METHOD

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Journal of Computational Mathematics 2024年第2期42卷 313-336页

作者： Wenli yang Zhongyi Huang Wei zhu School of Mathematics China University of Mining and TechnologyXuzhou 221116China Department of Mathematics Tsinghua UniversityBeijing 100084China Department of Mathematics University of AlabamaTuscaloosaAL 35487USA

In this paper,we propose using the tailored finite point method(TFPM)to solve the resulting parabolic or elliptic equations when minimizing the Huber regularization based image super-resolution model using the augmented Lagrangian method(ALM).The Hu-ber regularization based image super-resolution model can ameliorate the staircase for restored *** employs the method of weighted residuals with collocation tech-nique,which helps get more accurate approximate solutions to the equations and reserve more details in restored *** compare the new schemes with the Marquina-Osher model,the image super-resolution convolutional neural network(SRCNN)and the classical interpolation methods:bilinear interpolation,nearest-neighbor interpolation and bicubic *** experiments are presented to demonstrate that with the new schemes the quality of the super-resolution images has been *** these,the existence of the minimizer of the Huber regularization based image super-resolution model and the convergence of the proposed algorithm are also established in this paper.

关键词： Image super-resolution Variational model Augmented Lagrangian methods Tailored finite point method

Vector Radiative Transfer in a Vertically Inhomogeneous Scattering and Emitting ***Ⅰ:A New Discrete Ordinate Method

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Journal of Meteorological Research 2024年第2期38卷 209-224页

作者： Ziqiang zhu Fuzhong WENG yang HAN Chinese Academy of Meteorological Sciences China Meteorological AdministrationBeijing 100081 University of Chinese Academy of Sciences Beijing 100049 CMA Earth System Modeling and Prediction Centre China Meteorological Administration(CMA)Beijing 100081 State Key Laboratory of Severe Weather Chinese Academy of Meteorological SciencesChina Meteorological AdministrationBeijing 100081

The original vector discrete ordinate radiative transfer(VDISORT)model takes into account Stokes radiance vector but derives its solution assuming azimuthal symmetric surface reflective matrix and atmospheric scattering phase matrix,such as the phase matrix derived from spherical particles or randomly oriented non-spherical *** this study,a new VDISORT is developed for general atmospheric scattering and boundary *** vector is decomposed into both sinusoidal and cosinusoidal harmonic modes,and the radiance at arbitrary viewing geometry is solved directly by adding two zero-weighted points in the Gaussian quadrature *** complex eigenvalues in homogeneous solutions are also taken into full *** accuracy of VDISORT model is comprehensively validated by four cases:Rayleigh scattering case,the spherical particle scattering case with the Legendre expansion coefficients of 0th-13th orders of the phase matrix(hereinafter L13),L13 with a polarized source,and the randomoriented oblate particle scattering case with the Legendre expansion coefficients of 0th-11th orders of the phase matrix(hereinafter L11).In all cases,the simulated radiances agree well with the benchmarks,with absolute biases less than 0.0065,0.0006,and 0.0008 for Rayleigh,unpolarized L13,and L11,*** a polarized bidirectional reflection distribution function(pBRDF)matrix is used as the lower boundary condition,VDISORT is now able to handle fully coupled atmospheric and surface polarimetric radiative transfer processes.

关键词： radiative transfer discrete ordinate polarization Stokes vector vector discrete ordinate radiative transfer(VDISORT)

Optimal Energy Efficiency Based High-speed Flying Control Method for Hydraulic Quadruped Robot

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Journal of Bionic Engineering 2024年第3期21卷 1156-1173页

作者： Qingjun yang Zhenyang Zhang Rui zhu Dianxin Wang School of Mechatronics Engineering Harbin Institute of TechnologyHarbin150000China Nanjing Chenguang Group Co.Ltd Nanjing210006China

Herein,a control method based on the optimal energy efficiency of a hydraulic quadruped robot was proposed,which not only realizes the optimal energy efficiency of flying trot gait but also ensures the stability of high-speed ***,the energy consumption per unit distance was adopted as the energy efficiency evaluation index based on the constant pressure oil supply characteristics of the hydraulic system,and the global optimization algorithm was adopted to solve the optimal ***,the gait parameters that affect the energy efficiency of quadruped were analyzed and the mapping relationship between each parameter and energy efficiency was captured,so as to select the optimum combination of energy efficiency parameters,which is significant to improve endurance ***,to ensure the stability of the high-speed flying trot gait motion of the hydraulic quadruped robot,the active compliance control strategy was ***,the proposed method was successfully verified by simulations and *** experimental results reveal that the flying trot gait of the hydraulic quadruped robot can be stably controlled at a speed of 2.2 m/s.

关键词： Hydraulic quadruped robot Flying trot Energy efficiency Active compliance control

Fast solution to the free return orbit's reachable domain of the manned lunar mission by deep neural network

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Journal of Systems Engineering and Electronics 2024年第2期35卷 495-508页

作者： yang Luyi LI Haiyang ZHANG Jin zhu Yuehe College of Aerospace Science and Engineering National University of Defense TechnologyChangsha 410073China China Astronauts Research and Training Center Beijing 100094China Hunan Key Laboratory of Intelligent Planning and Simulation for Aerospace Missions Changsha 410073China

It is important to calculate the reachable domain(RD)of the manned lunar mission to evaluate whether a lunar landing site could be reached by the spacecraft. In this paper, the RD of free return orbits is quickly evaluated and calculated via the classification and regression neural networks. An efficient databasegeneration method is developed for obtaining eight types of free return orbits and then the RD is defined by the orbit’s inclination and right ascension of ascending node(RAAN) at the perilune. A classify neural network and a regression network are trained respectively. The former is built for classifying the type of the RD, and the latter is built for calculating the inclination and RAAN of the RD. The simulation results show that two neural networks are well trained. The classification model has an accuracy of more than 99% and the mean square error of the regression model is less than 0.01°on the test set. Moreover, a serial strategy is proposed to combine the two surrogate models and a recognition tool is built to evaluate whether a lunar site could be reached. The proposed deep learning method shows the superiority in computation efficiency compared with the traditional double two-body model.

关键词： manned lunar mission free return orbit reachable domain(RD) deep neural network computation efficiency

Exogeneous metal ions as therapeutic agents in cardiovascular disease and their delivery strategies

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Regenerative Biomaterials 2024年第2期3卷 1-16页

作者： Xiaoqian Hong Geer Tian yang zhu Tanchen Ren Department of Cardiology of the Second Affliated Hospital and State Key Laboratory of Transvascular Implantation Devices Cardiovascular Key Laboratory of Zhejiang ProvinceZhejiang University School of MedicineHangzhou 310o09China Binjiang Institute of Zhejiang University Hangzhou 310053China MOE Key Laboratory of Macromolecular Synthesis and Functionalization Department of Polymer Science and EngineeringZhejiang UniversityHangzhou 310027China

Metal ions participate in many metabolic processes in the human body,and their homeostasis is crucial for *** cardiovascular diseases(CVDs),the equilibriums of metal ions are frequently interrupted,which are related to a variety of disturbances of physiological processes leading to abnormal cardiac *** supplement of metal ions has the potential to work as therapeutic strategies for the treatment of *** with other therapeutic drugs,metal ions possess broad availability,good stability and safety and diverse drug delivery *** delivery strategies of metal ions are important to exert their ther-apeutic effects and reduce the potential toxic side effects for cardiovascular applications,which are also receiving increasing *** local delivery strategies for metal ions based on various biomaterials are constantly being *** this review,we comprehensively summarized the positive roles of metal ions in the treatment of cVDs from three aspects:protecting cells from oxidative stress,inducing angiogenesis,and adjusting the functions of ion *** addition,we introduced the transferability of metal ions in vascular reconstruction and cardiac tissue repair,as well as the currently available engineered strategies for the precise delivery of metal ions,such as integrated with nanoparticles,hydrogels and scaffolds.

关键词： metal ions cardiovascular disease tissue engineering oxidative stress angiogenesis ion channel