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A grasp planning algorithm under uneven contact point distribution scenario for space non-cooperative target capture

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Chinese Journal of Aeronautics 2023年第11期36卷 452-464页

作者： Bicheng CAI Chengfei YUE Fan WU Xueqin CHEN Yunhai GENG research Center of the Satellite Technology Harbin Institute of TechnologyHarbin 150001China institute of Space science and applied Technology Harbin Institute of Technology ShenzhenShenzhen 518055China

The contact point configuration should be carefully chosen to ensure a stable capture,especially for the non-cooperative target capture mission using multi-armed *** this work scenario,the contact points on the base and on the arms are distributed on the opposite side of the ***,large forces will be *** cope with this problem,an uneven-oriented distribution union criterion is *** union criterion contains a virtual symmetrical criterion and a geometry *** virtual symmetrical contact point criterion is derived from the proof of the force closure principle using computational geometry to ensure a stable grasp,and the geometry criterion is calculated by the volume of the minimum polyhedron formed by the contact points to get a wide-range *** further accelerate the optimization rate and enhance the global search ability,a line array modeling method and a continuous-discrete global search algorithm are *** line array modeling method reduces the workload of calculating the descent direction and the gradient available,while the continuous-discrete global search algorithm reducing the optimization *** a highly efficient grasping is achieved and the corresponding contact point is ***,an exhaustive verification is conducted to numerically analyze the disturbance resistance ability,and simulation results demonstrate the effectiveness of the proposed algorithms.

关键词： Grasp planning Line array modeling Space debris removal Space non-cooperative target capture Virtual symmetrical contact point method

Quantum second-order optimization algorithm for general polynomials

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science China(Physics,Mechanics & Astronomy) 2021年第10期64卷 54-63页

作者： Pan Gao Keren Li Shijie Wei Gui-Lu Long State Key Laboratory of Low-Dimensional Quantum Physics and Department of Physics Tsinghua UniversityBeijing 100084China shenzhen jl computational science and applied research institute Shenzhen 518109China Beijing Academy of Quantum Information sciences Beijing 100193China Beijing National research Center for Information science and Technology and School of Information Tsinghua UniversityBeijing 100084China Frontier science Center for Quantum Information Beijing 100084China

Quantum optimization algorithms can outperform their classical counterpart and are key in modern technology. The second-order optimization algorithm(the Newton algorithm) is a critical optimization method, speeding up the convergence by employing the second-order derivative of loss functions in addition to their first derivative. Here, we propose a new quantum second-order optimization algorithm for general polynomials with a computational complexity of O(poly(log d)). We use this algorithm to solve the nonlinear equation and learning parameter problems in factorization machines. Numerical simulations show that our new algorithm is faster than its classical counterpart and the first-order quantum gradient descent algorithm. While existing quantum Newton optimization algorithms apply only to homogeneous polynomials, our new algorithm can be used in the case of general polynomials, which are more widely present in real applications.

关键词： quantum computation quantum algorithm optimization

Improved error estimates for a modified exponential Euler method for the semilinear stochastic heat equation with rough initial data

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science China Mathematics 2024年第12期67卷 2873-2898页

作者： Xinping Gui Buyang Li Jilu Wang Beijing computational science research Center Beijing 100193China Department of applied Mathematics The Hong Kong Polytechnic UniversityHong KongChina School of science Harbin Institute of TechnologyShenzhen 518055China

A class of stochastic Besov spaces BpL^(2)(Ω;˙H^(α)(O)),1≤p≤∞andα∈[−2,2],is introduced to characterize the regularity of the noise in the semilinear stochastic heat equation du−Δudt=f(u)dt+dW(t),under the following conditions for someα∈(0,1]:||∫_(0)^(t)e−(t−s)^(A)dW(s)||L^(2)(Ω;L^(2)(O))≤C^(t^(α/2))and||∫_(0)^(t)e−(t−s)^(A)dW(s)||_B^(∞)L^(2)(Ω:H^(α)(O))≤C..The conditions above are shown to be satisfied by both trace-class noises(withα=1)and one-dimensional space-time white noises(withα=1/2).The latter would fail to satisfy the conditions withα=1/2 if the stochastic Besov norm||·||B∞L^(2)(Ω;˙H^(α)(O))is replaced by the classical Sobolev norm||·||L^(2)(Ω;˙Hα(O)),and this often causes reduction of the convergence order in the numerical analysis of the semilinear stochastic heat *** this paper,the convergence of a modified exponential Euler method,with a spectral method for spatial discretization,is proved to have orderαin both the time and space for possibly nonsmooth initial data in L^(4)(Ω;˙H^(β)(O))withβ>−1,by utilizing the real interpolation properties of the stochastic Besov spaces and a class of locally refined stepsizes to resolve the singularity of the solution at t=0.

关键词： semilinear stochastic heat equation additive noise space-time white noise exponential Euler method spectral method strong convergence stochastic Besov space real interpolation

Unified gas-kinetic wave-particle methods IV: multi-species gas mixture and plasma transport

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Advances in Aerodynamics 2021年第1期3卷 186-216页

作者： Chang Liu Kun Xu Department of Mathematics Hong Kong University of Science and TechnologyHong KongChina institute of applied Physics and computational Mathematics Beijing 100088China shenzhen research institute Hong Kong University of Science and TechnologyShenzhen 518057China.

In this paper,we extend the unified gas-kinetic wave-particle(UGKWP)methods to the multi-species gas mixture and multiscale plasma *** construction of the scheme is based on the direct modeling on the mesh size and time step scales,and the local cell’s Knudsen number determines the flow *** proposed scheme has the multiscale and asymptotic complexity diminishing *** multiscale property means that according to the cell’s Knudsen number the scheme can capture the non-equilibrium flow physics when the cell size is on the kinetic mean free path scale,and preserve the asymptotic Euler,Navier-Stokes,and magnetohydrodynamics(MHD)when the cell size is on the hydrodynamic scale and is much larger than the particle mean free *** asymptotic complexity diminishing property means that the total degrees of freedom of the scheme reduce automatically with the decreasing of the cell’s Knudsen *** the continuum regime,the scheme automatically degenerates from a kinetic solver to a hydrodynamic *** the UGKWP,the evolution of microscopic velocity distribution is coupled with the evolution of macroscopic variables,and the particle evolution as well as the macroscopic fluxes is modeled from a time accumulating solution of kinetic scale particle transport and collision up to a time step *** plasma transport,the current scheme provides a smooth transition from particle-in-cell(PIC)method in the rarefied regime to the magnetohydrodynamic solver in the continuum *** the continuum limit,the cell size and time step of the UGKWP method are not restricted by the particle mean free path and mean collision *** the highly magnetized regime,the cell size and time step are not restricted by the Debye length and plasma cyclotron *** multiscale and asymptotic complexity diminishing properties of the scheme are verified by numerical tests in multiple flow regimes.

关键词： Unified gas-kinetic wave-particle method Multiscale modeling Gas mixture Plasma transport

An Iterative Thresholding Method for the Minimum Compliance Problem

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Communications in computational Physics 2023年第4期33卷 1189-1216页

作者： Luyu Cen Wei Hu Dong Wang Xiaoping Wang Department of Mathematics Hong Kong University of Science and TechnologyClear Water BayKowloonHong KongChina The Program in applied and computational Mathematics Princeton UniversityPrincetonNew JerseyUSA School of science and Engineering The Chinese University of Hong KongShenzhenGuangdong 518172China shenzhen International Center for Industrial and applied Mathematics Shenzhen Research Institute of Big DataGuangdong 518172China

In this paper,we propose a simple energy decaying iterative thresholding algorithm to solve the two-phase minimum compliance *** material domain is implicitly represented by its characteristic function,and the problem is formulated into a minimization problem by the principle of minimum complementary *** prove that the energy is decreasing in each *** effective continuation schemes are proposed to avoid trapping into the local *** results on 2D isotropic linear material demonstrate the effectiveness of the proposed methods.

关键词： Minimum compliance convolution thresholding linear elasticity

Preparation of pseudo-pure states for NMR quantum computing with one ancillary qubit

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science China(Physics,Mechanics & Astronomy) 2019年第6期62卷 13-20页

作者： Tao Xin Liang Hao Shi-Yao Hou Guan-Ru Feng Gui-Lu Long State Key Laboratory of Low-dimensional Quantum Physics and Department of Physics Tsinghua University shenzhen institute for Quantum science and Engineering Southern University of Science and Technology Center for Quantum Computing Peng Cheng Laboratory shenzhen Key Laboratory of Quantum science and Engineering Southern University of Science and Technology institute of applied Physics and computational Mathematics Center for computational sciences Sichuan Normal University College of Physics and Electronic Engineering Sichuan Normal University institute for Quantum Computing Waterloo Tsinghua National Laboratory of Information science and Technology The Innovative Center of Quantum Matter

Quantum state preparation plays an equally important role as quantum operations and measurements in quantum information processing. The previous methods for initialization require either an exponential number of experiments, or cause signal reduction or place restrictions on molecular structures. In this study, we propose three types of quantum circuits for preparing the pseudo-pure states of(n-1) qubits in the n-coupled Hilbert space, which simply needs the assistance of one ancilla spin and two different experiments independent of n. Most importantly, our methods work well on homo-nuclear and hetero-nuclear molecules without the reduction of signals in the gradient field. As a proof-of-principle demonstration, we experimentally prepared the pseudo-pure states of heteronuclear 2-qubit and homonuclear 4-qubit molecules using a nuclear magnetic resonance quantum information processor.

关键词： quantum state preparation nuclear magnetic resonance quantum algorithms

Universal bound on sampling bosons in linear optics and its computational implications

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National science Review 2019年第4期6卷 719-729页

作者： Man-Hong Yung Xun Gao Joonsuk Huh shenzhen institute for Quantum science and Engineering and Department of Physics Southern University of Science and Technology shenzhen Key Laboratory of Quantum science and Engineering Southern University of Science and Technology Central research institute Huawei Technologies Center for Quantum Information Institute for Interdisciplinary Information SciencesTsinghua University Department of Chemistry Sungkyunkwan University

In linear optics, photons are scattered in a network through passive optical elements including beam splitters and phase shifters, leading to many intriguing applications in physics, such as Mach–Zehnder interferometry, the Hong–Ou–Mandel effect, and tests of fundamental quantum mechanics. Here we present the fundamental limit in the transition amplitudes of bosons, applicable to all physical linear optical networks. Apart from boson sampling, this transition bound results in many other interesting applications,including behaviors of Bose–Einstein condensates(BEC) in optical networks, counterparts of Hong–Ou–Mandel effects for multiple photons, and approximating permanents of matrices. In addition,this general bound implies the existence of a polynomial-time randomized algorithm for estimating the transition amplitudes of bosons, which represents a solution to an open problem raised by Aaronson and Hance(Quantum Inf Comput 2012; 14: 541–59). Consequently, this bound implies that computational decision problems encoded in linear optics, prepared and detected in the Fock basis, can be solved efficiently by classical computers within additive errors. Furthermore, our result also leads to a classical sampling algorithm that can be applied to calculate the many-body wave functions and the S-matrix of bosonic particles.

关键词： boson sampling quantum optics quantum supremacy linear optics computational complexity

Specialising neural network potentials for accurate properties and application to the mechanical response of titanium

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npj computational Materials 2021年第1期7卷 1908-1918页

作者： Tongqi Wen Rui Wang Lingyu Zhu Linfeng Zhang Han Wang David J.Srolovitz Zhaoxuan Wu Department of Materials science and Engineering City University of Hong KongKowloonHong KongSARChina Hong Kong institute for Advanced Study City University of Hong KongKowloonHong KongSARChina Beijing institute of Big Data research BeijingChina Laboratory of computational Physics Institute of Applied Physics and Computational MathematicsBeijingChina Department of Mechanical Engineering The University of Hong KongHong KongSARChina International Digital Economy Academy(IDEA) ShenzhenChina

Large scale atomistic simulations provide direct access to important materials phenomena not easily accessible to experiments or quantum mechanics-based calculation *** and efficient interatomic potentials are the key enabler,but their development remains a challenge for complex materials and/or complex *** learning potentials,such as the Deep Potential(DP)approach,provide robust means to produce general purpose interatomic ***,we provide a methodology for specialising machine learning potentials for high fidelity simulations of complex phenomena,where general potentials do not *** an example,we specialise a general purpose DP method to describe the mechanical response of two allotropes of titanium(in addition to other defect,thermodynamic and structural properties).The resulting DP correctly captures the structures,energies,elastic constants andγ-lines of Ti in both the HCP and BCC structures,as well as properties such as dislocation core structures,vacancy formation energies,phase transition temperatures,and thermal *** DP thus enables direct atomistic modelling of plastic and fracture behaviour of *** approach to specialising DP interatomic potential,DPspecX,for accurate reproduction of properties of interest“X”,is general and extensible to other systems and properties.

关键词： titanium enable neural

Predicting circRNA-Disease Associations by Using Multi-Biomolecular Networks Based on Variational Graph Auto-Encoder with Attention Mechanism

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Chinese Journal of Electronics 2024年第6期33卷 1526-1537页

作者： Jing YANG Xiujuan LEI Yi PAN School of Computer science Shaanxi Normal University Faculty of Computer science and Control Engineering Shenzhen Institute of Advanced TechnologyChinese Academy of Sciences shenzhen Key Laboratory of Intelligent Bioinformatics Shenzhen Institute of Advanced Technology

CircRNA-disease association(CDA) can provide a new direction for the treatment of diseases. However,traditional biological experiment is time-consuming and expensive, this urges us to propose the reliable computational model to predict the associations between circRNAs and diseases. And there is existing more and more evidence indicates that the combination of multi-biomolecular information can improve the prediction accuracy. We propose a novel computational model for CDA prediction named MBCDA, we collect the multi-biomolecular information including circRNA, disease, miRNA and lncRNA based on 6 databases, and construct three heterogeneous network among them, then the multi-heads graph attention networks are applied to these three networks to extract the features of circRNAs and diseases from different views, the obtained features are put into variational graph auto-encoder(VGAE) network to learn the latent distributions of the nodes, a fully connected neural network is adopted to further process the output of VGAE and uses sigmoid function to obtain the predicted probabilities of circRNA-disease *** a result, MBCDA achieved the values of AUC and AUPR under 5-fold cross-validation of 0.893 and 0.887. MBCDA was applied to the analysis of the top-25 predicted associations between circRNAs and diseases, these experimental results show that our proposed MBCDA is a powerful computational model for CDA prediction.

关键词： Knowledge engineering Attention mechanisms computational modeling Biological system modeling Predictive models Feature extraction Heterogeneous networks Topology Data mining Diseases