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Dynamic motion of quadrupedal robots on ch.llenging terrain:a kinodynamic optimization approach

Frontiers of Mech.nical Engineering 2024年第3期19卷 23-40页

作者： qi LI lei DING Xin LUO Engineering Research.Center of Hubei Province for Clothing Information Wuhan 430200China Sch.ol of Computer Science and Artificial Intelligence Wuhan Textile UniversityWuhan 430200China State Key Laboratory of Digital Manufacturing Equipment and Tech.ology Huazhong University of Science and TechnologyWuhan 430074China

The dynamic motion of quadrupedal robots on ch.llenging terrain generally requires elaborate spatial–temporal kinodynamic motion planning and accurate control at higher refresh rate in comparison with regular ***,conventional quadrupedal robots usually generate relatively coarse planning and employ motion replanning or reactive strategies to handle terrain *** resultant complex and computation-intensive controller may lead to nonoptimal motions or the breaking of locomotion *** this paper,a kinodynamic optimization approach.is *** generate long-horizon optimal predictions of the kinematic and dynamic behavior of the quadruped robot on ch.llenging terrain,we formulate motion planning as an optimization problem;jointly treat the foot’s locations,contact forces,and torso motions as decision variables;combine smooth motion and minimal energy consumption as the objective function;and explicitly represent feasible foothold region and friction constraints based on terrain *** track the generated motions accurately and stably,we employ a whole-body controller to compute reference position and velocity commands,which.are fed forward to joint controllers of the robot’s *** verify the effectiveness of the developed approach.through simulation and on a physical quadruped robot *** show that the quadruped robot can successfully traverse a 30°slope and 43% of nominal leg length high step while maintaining the rhythm of dynamic trot gait.

关键词： quadrupedal robot kinodynamic planning nonlinear optimization ch.llenging terrain whole-body control

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Buckling optimization of curvilinear fiber-reinforced composite structures using a parametric level set method

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Frontiers of Mech.nical Engineering 2024年第1期19卷 149-160页

作者： Ye TIAN Tielin SHI qi XIA State Key Laboratory of Intelligent Manufacturing Equipment and Tech.ology Huazhong University of Science and TechnologyWuhan 430074China

Owing to their excellent performance and large design space,curvilinear fiber-reinforced composite structures have gained considerable attention in engineering fields such.as aerospace and *** addition to the stiffness and strength of such.structures,their stability also needs to be taken into account in the *** study proposes a level-set-based optimization framework for maximizing the buckling load of curvilinear fiber-reinforced composite *** the proposed method,the contours of the level set function are used to represent fiber *** a composite laminate with a certain number of layers,one level set function is defined by radial basis functions and expansion coefficients for each.***,the fiber angle at an arbitrary point is the tangent orientation of the contour through this *** the finite element of buckling,the stiffness and geometry matrices of an element are related to the fiber angle at the element *** study considers the parallelism constraint for fiber *** the sensitivity calculation of the objective and constraint functions,the method of moving asymptotes is utilized to iteratively update all the expansion coefficients regarded as design *** numerical examples under different boundary conditions are given to validate the proposed *** show that the optimized curved fiber paths tend to be parallel and equidistant regardless of whether the composite laminates contain holes or ***,the buckling resistance of the final design is significantly improved.

关键词： buckling optimization curvilinear fiber composite structure level set method manufacturing constraint

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ANALYSIS OF THE IMPLICIT-EXPLICIT ULTRA-WEAK DISCONTINUOUS GAleRKIN METHOD FOR CONVECTION-DIFFUSION PROBleMS

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Journal of Computational Mathematics 2024年第1期42卷 1-23页

作者： Haijin Wang Anping Xu qi Tao Sch.ol of Science Nanjing University of Posts and TelecommunicationsNanjing 210023China Beijing Computational Science Research.Center Beijing 100193China

In this paper,we first present the optimal error estimates of the semi-discrete ultra-weak discontinuous Galerkin method for solving one-dimensional linear convection-diffusion ***,coupling with a kind of Runge-Kutta type implicit-explicit time discretization which.treats the convection term explicitly and the diffusion term implicitly,we analyze the stability and error estimates of the corresponding fully discrete *** fully discrete sch.mes are proved to be stable if the time-stepτ≤τ0,whereτ0 is a constant independent of the mesh-size ***,by the aid of a special projection and a careful estimate for the convection term,the optimal error estimate is also obtained for the third order fully discrete *** experiments are displayed to verify the theoretical results.

关键词： The ultra-weak discontinuous Galerkin method Convection-diffusion Implicitexplicit time discretization Stability Error estimate

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π-conjugated ch.omophore functionalized high-nuclearity titanium-oxo clusters containing structural unit of anatase for photocatalytic selective oxidation of sulfides

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Rare Metals 2024年第4期43卷 1736-1746页

作者： Ling-Rong Liao Dong-ch.n Zheng Pin-Xi Ou qi-Xin Zhao Wei-Min Xuan qi Zheng State Key Laboratory for Modification of ch.mical Fibers and Polymer Materials&College of Materials Science and Engineering Donghua UniversityShanghai201620China State Key Laboratory for Modification of ch.mical Fibers and Polymer Materials and College of ch.mistry and ch.mical Engineering Donghua UniversityShanghai 201620China

N-doping has significant influence in manipulating the properties of TiO_(2),and this has stimulated the development of N-donor-functionalized titanium-oxo clusters(TOCs)as molecular models to study the structure-property ***,the structural type and photoresponsive application are still limited for such.TOCs,especially regarding the high-nuclearity TOCs that contain structure unit of TiO_(2)for ***,we showed the synthesis of a series of high-nuclearity TOCs 1-3 compounds usingπ-conjugated 1,10-phenanthroline(phen)as ch.omophore and N-donor functional *** 1 features cocrystal structure composed of one[Ti_(26)]~(2+)and half[Ti_(22)]~(2+),which.renders it as the first cocrystallized TOC containing two positively ch.rged species and phen-functionalized TOC showing the highest nuclearity up to 37 Ti *** adjusting the synthetic conditions,the individual{Ti_(22)}and{Ti_(26)}clusters can also be isolated as Compounds 2 and 3,*** core structure of{Ti_(22)}is mainly constructed from four lacunary{Ti_(4)}derived from pentagonal{Ti(Ti)_5}unit,while{Ti_(26)}is built from four complete{Ti(Ti)_5}***,a{Ti_8O_(14)}structure unit of anatase TiO_(2)can be identified in{Ti_(26)}.Based on the unique structural features and proper photophysical and photoch.mical properties of Compounds 1-3,they are applied for photocatalytic *** to the presence of anatase structure unit in{Ti_(26)}and the synergistic effect from{Ti_(22)}and{Ti_(26)},the catalytic performance presents in the order of Compound 1>Compound 3>Compound *** work provides excellent models to understand the structureproperty relationship from the perspective of cocrystallization and Ti-O binding model and will further promote the application of TOCs as functional catalysts for organic transformation.

关键词： Titanium-oxo cluster Molecular model of anatase TiO_(2) High nuclearity π-conjugated ch.omophore Photocatalytic sulfoxidation

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Optimal AP Deployment in Cell-Free Massive MIMO Systems with LoS/NLoS Transmissions:A Stoch.stic Geometry Approach

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ch.na Communications 2024年第9期21卷 146-158页

作者： Jiang Ling Zhang qi Zhu Hongbo Jiangsu Key Laboratory of Wireless Communications Nanjing University of Posts and TelecommunicationsNanjing 210003China

Cell-free massive multiple-input multipleoutput(MIMO)is a promising tech.ology for future wireless communications,where a large number of distributed access points(APs)simultaneously serve all users over the same time-frequency *** users and APs may locate close to each.other,the line-of-sight(Lo S)transmission occurs more frequently in cell-free massive MIMO ***,in this paper,we investigate the cell-free massive MIMO system with Lo S and non-line-of-sight(NLo S)transmissions,where APs and users are both distributed according to Poisson point *** tools from stoch.stic geometry,we derive a tight lower bound for the user downlink ach.evable rate and we further obtain the energy efficiency(EE)by considering the power consumption on downlink payload transmissions and circuitry *** on the analysis,the optimal AP density and AP antenna number that maximize the EE are *** is found that compared with the previous work that only considers NLo S transmissions,the actual optimal AP density should be much.smaller,and the maximized EE is actually much.higher.

关键词： cell-free massive MIMO energy efficiency LoS/NLoS transmissions stoch.stic geometry

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One-shot Face Reenactment with Dense Correspondence Estimation

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Mach.ne Intelligence Research 2024年第5期21卷 941-953页

作者： Yunfan Liu qi Li Zhenan Sun Sch.ol of Artificial Intelligence University of Chinese Academy of SciencesBeijing100049China Center for Research.on Intelligent Perception and Computing Institute of AutomationChinese Academy of SciencesBeijing100190China

One-shot face reenactment is a ch.llenging task due to the identity mismatch.between source and driving *** existing methods fail to completely eliminate the interference of driving subjects’identity information,which.may lead to face shape distortion and undermine the realism of reenactment *** solve this problem,in this paper,we propose using a 3D morphable model(3DMM)for explicit facial semantic decomposition and identity *** of using 3D coefficients alone for reenactment control,we take advantage of the generative ability of 3DMM to render textured face *** proxies contain abundant yet compact geometric and semantic information of human faces,which.enables us to compute the face motion field between source and driving images by estimating the dense *** this way,we can approximate reenactment results by warping source images according to the motion field,and a generative adversarial network(GAN)is adopted to further improve the visual quality of warping *** experiments on various datasets demonstrate the advantages of the proposed method over existing state-of-the-art bench.arks in both identity preservation and reenactment fulfillment.

关键词： Generative adversarial networks face image manipulation face image synthesis face reenactment 3D morphable model

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Quantum correlations in a ch.in-type quantum network

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Communications in Theoretical Physics 2024年第6期76卷 77-91页

作者： Xiaofei qi Aihong Zhai Lihua Yang Sch.ol of Mathematical Science Shanxi UniversityTaiyuan 030006China Key Laboratory of Complex Systems and Data Science of Ministry of Education Shanxi UniversityTaiyuan 030006China Sch.ol of Mathematics and Information Tech.ology Yuncheng UniversityYuncheng 044000China

A quantum network concerns several independent entangled resources and can create strong quantum correlations by performing joint measurements on some *** this paper,we discuss an n-partite ch.in network with each.of two neighboring observers sharing an arbitrary Bell state and all intermediate observers performing some positive-operator-valued measurements with parameterλ.The expressions of all post-measurement states between any two observers are obtained,and their quantifications of Bell nonlocality,Einstein-Podolsky-Rosen steering and entanglement with different ranges ofλare respectively detected and analyzed.

关键词： quantum correlation nonlocality entanglement ch.in-type quantum network

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Continuous Orbit Equivalence of Semigroup Actions

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Acta Mathematica Sinica,English Series 2024年第6期40卷 1581-1598页

作者： Xiang qi qiANG ch.ng Jun HOU Sch.ol of Mathematical Science Yangzhou UniversityYangzhou 225002P.R.China

We introduce notions of continuous orbit equivalence and its one-sided version for countable left Ore semigroup actions on compact spaces by surjective local homeomorphisms,and ch.racterize them in terms of the corresponding transformation groupoids and their operator *** particular,we show that two essentially free semigroup actions on totally disconnected compact spaces are continuously orbit equivalent if and only if there is a canonical abelian subalgebra preserving C^(∗)-isomorphism between the associated transformation groupoid C^(∗)-*** also give some examples of orbit equivalence,consider the special case of semigroup actions by homeomorphisms and relate continuous orbit equivalence of semigroup actions to that of the associated group actions.

关键词： Semigroup action continuous one-sided orbit equivalence continuous orbit equivalence groupoid C^(∗)-algebras

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Efficiently simulating the work distribution of multiple identical bosons with boson sampling

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Frontiers of physics 2024年第3期19卷 197-206页

作者： Wen-qiang Liu Zhang-qi Yin Center for Quantum Tech.ology Research.and Key Laboratory of Advanced Optoelectronic Quantum Arch.tecture and Measurements(MOE) School of PhysicsBeijing Institute of TechnologyBeijing 100081China

Boson sampling has been theoretically proposed and experimentally demonstrated to show quantum computational ***,it still lacks the deep understanding of the practical applications of boson *** we propose that boson sampling can be used to efficiently simulate the work distribution of multiple identical *** link the work distribution to boson sampling and numerically calculate the transition amplitude matrix between the single-boson eigenstates in a one-dimensional quantum piston system,and then map the matrix to a linear optical network of boson *** work distribution can be efficiently simulated by the output probabilities of boson sampling using the method of the grouped probability *** sch.me requires at most a polynomial number of the samples and the optical *** work opens up a new path towards the calculation of complex quantum work distribution using only photons and linear optics.

关键词： quantum simulation quantum work distribution boson sampling linear optic

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ch.racteristics and Genesis of Acid Drainage Contamination from a Rock Tunneling Project Site

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Journal of Earth Science 2024年第1期35卷 190-200页

作者： Yanyun Li Zejiao Luo Shihua qi Hubei Key Laboratory of Yangtze River Basin Environmental Aquatic Science School of Environmental StudiesChina University of GeosciencesWuhan 430078China State Key Laboratory of Biogeology and Environmental Geology China University of GeosciencesWuhan 430078China

While acid mine drainage(AMD)issues have become a topic of global concern,few studies have focused on acid drainage problems of non-mining *** conducted field research.and a series of laboratory experiments to investigate the ch.racteristics,release processes and formation of acid drainage *** rock samples and adjacent surface water,groundwater,soil and sediment samples were collected at a railway tunnel construction site in central ch.na,and various parameters,such.as the p H,mineral ion concentrations,and heavy metal concentrations,were *** on the measured concentrations,surface water and sediments were seriously contaminated by acids,sulfate salts and heavy *** in surface water showed a decreasing tendency as the distance from the spoils increased,while that in sediments showed a greater influence of coprecipitation and adsorption processes of heavy metal *** eluviation experiments of three rock samples indicated that R2(silty fine sandstone)was the most likely major acid drainage *** ferrooxidans was cultured and isolated from contaminated water to study the oxidation conditions during the release *** significant release of acid drainage when air and bacteria were both in the culture container suggested that oxygen and bacteria were necessary to produce acid drainage from spoils.

关键词： acid mine drainage heavy metals leach.ng oxidation

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