检索结果-南通市图书馆

Real-time recognition of human lower-limb locomotion based on exponential coordinates of relative rotations

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2021年第7期64卷 1423-1435页

作者： XU Sen ding Ye State Key Laboratory of Mechanical System and Vibration School of Mechanical EngineeringShanghai Jiao Tong UniversityShanghai200240China

This paper proposes a data-driven method using a parametric representation of relative rotations to classify human lower-limb locomotion, which is designed for wearable robots. Three Inertial measurement units(IMUs) are mounted on the subject's waist,left knee, and right knee, respectively. Features for classification comprise relative rotations, angular velocities, and waist acceleration. Those relative rotations are represented by the exponential coordinates. The rotation matrices are normalized by Karcher mean and then the Support Vector Machine(SVM) method is used to train the data. Experiments are conducted with a time-window size of less than 40 ms. Three SVM classifiers telling 3, 5 and 6 rough lower-limb locomotion types respectively are trained, and the average accuracies are all over 98%. With the combination of those rough SVM classifiers, an easy SVMbased ensembled-system is proposed to classify 16 fine locomotion types, achieving the average accuracy of 98.22%, and its latency is 18 ms when deployed to an onboard computer.

关键词： locomotion recognition exponential coordinate relative rotation support vector machine

Linearly Polarization-Sensitive Perovskite Photodetectors

在线全文

学校读者我要写书评

暂无评论

Nano-Micro Letters 2023年第6期15卷 428-435页

作者： Jie Sun Liming ding Center for Excellence in Nanoscience(CAS) Key Laboratory of Nanosystem and Hierarchical Fabrication(CAS)National Center for Nanoscience and TechnologyBeijing 100190People’s Republic of China University of Chinese Academy of Sciences Beijing 100049People’s Republic of China

Polarization means symmetry loss for light vibration along light propagation direction,which is a particular physical property of *** polarization state is indecipherable for most polarization-insensitive *** can carry and differentiate light information,and can be used in polarized light detection,polarization imaging and encryption communication[1].Photodetectors are the core component of some photoelectric devices[2]used in biomedical sensing,remote sensing,military field,etc.

关键词： Polarization symmetry polarized

Roadmap of the iron-based superconductor Majorana platform

在线全文

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2023年第6期66卷 3-17页

作者： Wenyao Liu Hong ding Beijing National Laboratory for Condensed Matter Physics Institute of PhysicsChinese Academy of SciencesBeijing 100190China School of Physical Sciences University of Chinese Academy of SciencesBeijing 100049China Laboratory for Assembly and Spectroscopy of Emergence Boston CollegeChestnut Hill 02215USA CAS Center for Excellence in Topological Quantum Computation University of Chinese Academy of SciencesBeijing 100190China Tsung-Dao Lee Institute School of Physics and AstronomyShanghai Jiao Tong UniversityShanghai 200240China

With a series of recent breakthroughs,iron-based superconductors(FeSC)with a topological Dirac surface state are becoming a promising material platform for hosting Majorana zero modes,which we refer to as the iron-Majorana *** platform uniquely combines high-Tcsuperconductivity,a topological band structure,and electron correlations into a single material,successfully avoiding the difficulties of achieving intrinsic p-wave topological superconductors and superconductor/topological insulator heterojunction *** most important advantages of the iron-Majorana platform are its wide topological region and large quasiparticle gap,which provide strong topological protection for pure Majorana zero modes(MZMs).When the superconductor/topological insulator heterojunction systems,e.g.,In As/Al nanowire,have the controversies of being trivial Majorana-like states,the iron-Majorana platform,which possesses well-understood physics and clear experimental evidence of vortex MZMs,is more likely to be a true ***,unlike the nanowire Majorana systems with clear theoretical proposals for braiding schemes,the iron-Majorana system has no concrete method for exchanging the vortex MZMs or constructing a topological *** this article,we propose a roadmap of the future efforts required for more physical exploration and achieving the non-Abelian exchange statistics of MZMs based on the iron-Majorana platform.

关键词： topological superconductor iron-based superconductor Majorana zero modes

基于模糊PID控制的拖拉机遥控转向系统研究

在线全文

学校读者我要写书评

暂无评论

农机化研究 2025年第3期47卷 234-241页

作者：刘九庆丁鹏于文吉东北林业大学机电工程学院哈尔滨150040

由于拖拉机实际作业环境较为恶劣,为保证驾驶员的安全,提出了一种拖拉机遥控转向系统的设计方案。首先,对拖拉机现有的液压转向系统进行了分析,并提出了遥控转向系统的结构设计和控制策略设计;然后,通过AMEsim和Simulink分别搭建了遥控... 详细信息

由于拖拉机实际作业环境较为恶劣,为保证驾驶员的安全,提出了一种拖拉机遥控转向系统的设计方案。首先,对拖拉机现有的液压转向系统进行了分析,并提出了遥控转向系统的结构设计和控制策略设计;然后,通过AMEsim和Simulink分别搭建了遥控转向系统的液压部分模型和模糊PID控制器并进行了联合仿真实验。实验结果表明:设计的遥控转向系统能够实现拖拉机的转向,模糊PID控制器相对于常规PID控制器的控制效果更好,阶跃响应时间由1.49 s缩短到1.07 s,正弦跟踪响应最大误差由0.028 m缩短到0.015 m,抗干扰性也更强。

关键词：拖拉机转向遥控转向系统模糊PID控制联合仿真

维普期刊数据库博看期刊

Effects of urban square entry layouts on spatial ventilation under different surrounding building conditions

在线全文

学校读者我要写书评

暂无评论

Building Simulation 2021年第2期14卷 377-390页

作者： Wei You Wowo ding School of Architecture and Urban Planning Nanjing UniversityNanjing210093China

Effective urban square ventilation is important for the living comfort and health of *** research aims to establish some principles of street entry layouts for urban square ventilation *** computational fluid dynamics(CFD)simulation techniques,two types of street entry squares(two-intersection and four-intersection)were investigated under the effect of surrounding *** indices—the spatial mean velocity(),air change rate(ACH)and mean flow rates()through the street entry and square roof—were calculated to quantify the square ventilation *** simulation results indicate that the surrounding buildings could influence the square space *** the surrounding building conditions change to a building coverage ratio of 0.25,theentering through the street entry can be reduced by 35%,and thewithin the square decreases by more than 45%.The optimal street entry layout design depends greatly on the wind *** the wind direction is perpendicular to the square street entry,the corner oblique-entry layout square shows a better ventilation performance than the other *** the wind direction is oblique to the square street entry,thedeclines greatly(up to 68%),and the lateral-entry layout design shows the best ventilation performance.

关键词： urban square street entry layout surrounding building spatial ventilation numerical simulation

A vertical track nonlinear energy sink

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Applied Mathematics and Mechanics(English Edition) 2024年第6期45卷 931-946页

作者： Meng LI Hu ding Shanghai Key Laboratory of Mechanics in Energy Engineering School of Mechanics and Engineering ScienceShanghai Frontier Science Center of MechanoinformaticsShanghai UniversityShanghai 200444China

Eliminating the effects of gravity and designing nonlinear energy sinks(NESs)that suppress vibration in the vertical direction is a challenging task with numerous damping *** this paper,the dynamic design of a vertical track nonlinear energy sink(VTNES)with zero linear stiffness in the vertical direction is proposed and realized for the first *** motion differential equations of the VTNES coupled with a linear oscillator(LO)are *** the strong nonlinearity considered of the VTNES,the steady-state response of the system is analyzed with the harmonic balance method(HBM),and the accuracy of the HBM is verified *** this basis,the VTNES prototype is manufactured,and its nonlinear stiffness is *** damping effect and dynamic characteristics of the VTNES are studied theoretically and *** results show that the VTNES has better damping effects when strong modulation responses(SMRs)***,even for small-amplitude vibration,the VTNES also has a good vibration suppression *** sum up,in order to suppress the vertical vibration,an NES is designed and developed,which can suppress the vertical vibration within certain ranges of the resonance frequency and the vibration intensity.

关键词： track nonlinear energy sink(TNES) vertical direction gravity nonlinear stiffness harmonic balance method(HBM) vibration control

Stability of Rarefaction Wave to the 1-D Piston Problem for the Pressure-Gradient Equations

在线全文

学校读者我要写书评

暂无评论

Chinese Annals of Mathematics,Series B 2019年第2期40卷 161-186页

作者： Min ding Department of Mathematics School of Science Wuhan University of Technology

The 1-D piston problem for the pressure gradient equations arising from the flux-splitting of the compressible Euler equations is considered. When the total variations of the initial data and the velocity of the piston are both sufficiently small, the author establishes the global existence of entropy solutions including a strong rarefaction wave without restriction on the strength by employing a modified wave front tracking method.

关键词： Piston problem Pressure gradient equations Rarefaction wave Wave front tracking method Interaction of waves

A Combinatorial Identity Arising from Symplectic Geometry

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2009年第9期25卷 1497-1506页

作者： Hao ding School of Mathematical Sciences Beijing Normal UniversityLaboratory of Mathematics and Complex Systems Ministry of Education Beijing 100875 P. R. China

In this note, we give a generalization of the famous combinational identity （-1）^nn! = Σk=1^n （nk）（-1）^kk^n arising from symplectic geometry.

关键词： Duistermaat-Heckman theorem Hamiltonian S^1 action Grassmann manifold weight

INFINITELY MANY HOMOCLINIC ORBITS FOR A CLASS OF HAMILTONIAN SYSTEMS WITH SYMMETRY

在线全文

学校读者我要写书评

暂无评论

Chinese Annals of Mathematics,Series B 1998年第2期19卷 167-178页

作者： ding YANHENG Acad Sinica Inst Math Beijing 100080 Peoples R China

This paper deals via variational methods with the existence of infinitely many homoclinic orbits for a class of first order time dependent Hamiltonian systems=JH z(t,z)without any periodicity assumption on H, providing that H(t,z) iseven with respect to z∈R 2N , superquadratic or subquadratic as |z|→∞, and satisfies some additional assumptions.

关键词： Variational method Homoclinic orbits Hamiltonian systems