检索结果-南通市图书馆

维普期刊数据库博看期刊

Conceptual design and control method for a noncontact annular electromagnetic stabilized satellite platform

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2024年第1期37卷 256-270页

作者： he LIAO Daixin wang yuan REN Weijie wang Institute of Astronautics Nanjing University of Aeronautics and AstronauticsNanjing 211106China Department of Basic Course Space Engineering UniversityHuairou DistrictBeijing 101416China

Disturbance-Free Payload(DFP)spacecraft can meet the requirements of ultra-high attitude pointing accuracy and stability for future space ***,as the main control actuators of DFP spacecraft,Linear Non-Contact Lorentz Actuators(LNCLAs)have control output problems with six-degree-of-freedom coupling and nonlinear effects,which will affect the attitude control performance of DFP *** solve this problem,a novel concept for Non-Contact Annular Electromagnetic Stabilized Satellite Platform(NCAESSP)is proposed in this *** concept is centered on replacing the LNCLAs with a non-contact annular electromagnetic actuator to solve the two problems mentioned ***,for the different control requirements of the payload module and the support module of the NCAESSP,a high-precision attitude controller based on the robust model matching method and a dual quaternion-based adaptive sliding mode controller are ***,the simulation results verify the feasibility and effectiveness of the proposed approach.

关键词： Disturbance-free payload Robust model matching Dual quaternion Sliding mode control Collision avoidance

A Nine-modes Truncation of the Plane Incompressible Navier-Stokes Equations

在线全文

学校读者我要写书评

暂无评论

Communications in Mathematical Research 2011年第4期27卷 297-306页

作者： wang he-yuan CUI YAN School of Science Liaoning University of Technology Jinzhou Liaoning 121001 Faculty of Information Science and Engineering Northeastern University Shenyang 110004

In this paper a nine-modes truncation of Navier-Stokes equations for a two-dimensional incompressible fluid on a torus is obtained. The stationary solutions, the existence of attractor and the global stability of the equations are firmly proved. What is more, that the force f acts on the mode ks and k7 respectively produces two systems, which lead to a much richer and varied phenomenon. Numerical simulation is given at last, which shows a stochastic behavior approached through an involved sequence of bifurcations.

关键词： the Navier-Stokes equation the strange attractor Lyapunov function,bifurcation chaos

Force Compensation Control for Electro-Hydraulic Servo System with Pump-Valve Compound Drive via QFT-DTOC

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Mechanical Engineering 2024年第2期37卷 228-246页

作者： Kaixian Ba yuan wang Xiaolong he Chunyu wang Bin Yu Yaliang Liu Xiangdong Kong hebei Provincial Key Laboratory of heavy Machinery Fluid Power Transmission and Control Qinhuangdao 066004China School of Mechanical Engineering Yanshan UniversityQinhuangdao 066004China National Engineering Research Center for Local Joint of Advanced Manufacturing Technology and Equipment Yanshan UniversityQinhuangdao 066004China

Each joint of a hydraulic-driven legged robot adopts a highly integrated hydraulic drive unit(HDU),which features a high power-weight ***,most HDUs are throttling-valve-controlled cylinder systems,which exhibit high energy *** contrast,pump control systems offer a high ***,their response ability is *** fully utilize the advantages of pump and valve control systems,in this study,a new type of pump-valve compound drive system(PCDS)is designed,which can not only effectively reduce the energy loss,but can also ensure the response speed and response accuracy of the HDUs in robot joints to satisfy the performance requirements of ***,considering the force control requirements of energy conservation,high precision,and fast response of the robot joint HDU,a nonlinear mathematical model of the PCDS force control system is first *** addition,pressure-flow nonlinearity,friction nonlinearity,load complexity and variability,and other factors affecting the system are considered,and a novel force control method based on quantitative feedback theory(QFT)and a disturbance torque observer(DTO)is designed,which is denoted as QFT-DTOC *** method improves the control accuracy and robustness of the force control system,reduces the effect of the disturbance torque on the control performance of the servo motor,and improves the overall force control performance of the ***,experimental verification is performed using the PCDS performance test *** experimental results and quantitative data show that the QFT-DTOC proposed herein can significantly improve the force control performance of the *** relevant force control method can be used as a bottom-control method for the hydraulic servo system to provide a foundation for implementing the top-level trajectory planning of the robot.

关键词： Legged robot Pump-valve compound drive system(PCDS) Force compensation control Quantitative feedback theory(QFT) Disturbance torque observer(DTO)

一种基于CATIA V6的轴系三维设计方法

在线全文

学校读者我要写书评

暂无评论

价值工程 2024年第14期43卷 71-75页

作者：高启王帅皓杨敬豪徐思豪郑超王贺远中国船舶及海洋工程设计研究院上海200011

本文基于CATIA V6软件平台,设计针对船舶轴系的三维建模方法。文章将船舶轴系设计需求和三维参数化建模相结合,考虑技术实现难点,利用多级骨架,实体建模,二次开发等多种CATIA软件功能,逐步提高船舶轴系设计过程中建模效率,模型关联性,... 详细信息

本文基于CATIA V6软件平台,设计针对船舶轴系的三维建模方法。文章将船舶轴系设计需求和三维参数化建模相结合,考虑技术实现难点,利用多级骨架,实体建模,二次开发等多种CATIA软件功能,逐步提高船舶轴系设计过程中建模效率,模型关联性,三维出图质量。在实际建模应用中体现出此方法在模型迭代更新,建模效率、质量等方面有显著优越性。此设计建模方法可结合实际工程需求,适用于除船舶轴系的其它回转体结构机械乃至更多种复杂机械设备的设计。

关键词： CATIA V6 船舶轴系三维设计三维出图

维普期刊数据库博看期刊

Recent progress on impact induced reaction mechanism of reactive alloys

在线全文

学校读者我要写书评

暂无评论

Defence Technology（防务技术） 2024年第7期37卷 69-95页

作者： Yansong Yang Chuanting wang yuanpei Meng Yue Ma Lei Guo yuan he Zhichao Sun Yong he School of Mechanical Engineering Nanjing University of Science and TechnologyNanjing 210094JiangsuChina

In recent years,in order to improve the destructive effectiveness of munitions,the use of new types of destructive elements is an important way to improve destructive *** a new type of reactive material,reactive alloy contains a large portion of reactive metal elements(Al,Mg,Ti,Zr,etc.),which breaks up under high-velocity impact conditions,generating a large number of high-temperature combustible fragments,which undergo a violent combustion reaction with *** with traditional metal polymers(Al-PTFE)and other reactive composites,it has higher density and strength,excellent mechanical properties and broader application ***,researchers have mainly investigated the impact energy release mechanism of reactive alloys through impact tests,and found that there are several important stages in the process of the material from fragmentation to reaction,i.e.,impact fragmentation of the material,rapid heating and combustion *** paper focuses on three problems that need to be solved in the impact-induced energy release process of reactive alloys,namely:the fragmentation mechanism and size distribution law of the fragments produced by the impact of the material on the target,the relationship between the transient temperatures and the size of the fragments,and the reaction temperatures and size thresholds of the fragments to undergo the chemical *** current status of the research of the above problems is reviewed,some potential directions to reveal the impact induced reaction mechanism of reactive alloy is discussed.

关键词： Reactive alloys Impact Fragmentation Mass and size distribution Shock temperature rise Adiabatic shear Combustion

Expanding the toolbox of metal-free organic halide perovskite for X-ray detection

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2024年第9期35卷 102-110页

作者： Xiuwen Xu Quan Zhou Yacong wang Yunjie he Qiang wang yuan wang Bing Chen College of Electronic and Optical Engineering and College of Flexible Electronics(Future Technology) Nanjing University of Posts and TelecommunicationsNanjing 210023China Laboratory for Biomaterials and Drug Delivery Department of AnesthesiologyDivision of Critical Care MedicineBoston Children’s HospitalHarvard Medical SchoolBostonMA 02115United States

X-ray detection plays a crucial role across various aspects of our daily lives,encompassing medical diagnoses,security screenings,and non-destructive examinations in industrial *** the wide array of application contexts,a wealth of opportunities is entailed with the practical utilization of both organic and inorganic X-ray detection materials.A novel and promising contender in this realm is the emergence of metal-free organic halide perovskites(O-PVSKs),offering great opportunities and tremendous potential in X-ray *** potential can be attributed to the distinct crystalline configuration of O-PVSKs,where organic constituents are structured into an ABX3perovskite ***,O-PVSKs exhibit captivating characteristics reminiscent of organic materials,such as lightweight nature and modifiability,all while retaining the distinctive traits associated with halide perovskites ranging from diverse structures to tunable optoelectronic *** review article delves into the intrinsic attributes of O-PVSKs and critically examines the viability of O-PVSKs in X-ray detection,through which key features that distinguish O-PVSKs from traditional organic semiconductors and perovskites are *** is followed by a perspective given on their future avenues for exploration.

关键词： Metal-free perovskites X-ray detection Electronic band structure Carrier transport Ion migration

Three-dimensional thermohaline structure estimation derived from HY-2 satellite data over the Maritime Silk Road and its applications

在线全文

学校读者我要写书评

暂无评论

Acta Oceanologica Sinica 2024年第5期43卷 41-53页

作者： Zhiqiang Chen Xidong wang Xiangyu Wu yuan Cao Zikang he Dakui wang Jian Chen Key Laboratory of Marine Hazards Forecasting Ministry of Natural ResourcesHohai UniversityNanjing 210024China Laboratory for Regional Oceanography and Numercial Modeling Qingdao Marine Science and Technology CenterQingdao 266061China National Marine Environmental Forecasting Center Ministry of Natural ResourcesBeijing 100081China Beijing Institute of Applied Meteorology Beijing 100029China

Estimated ocean subsurface fields derived from satellite observations provide potential data sources for operational marine environmental monitoring and prediction *** study employs a statistic regression reconstruction method,in combination with domestic autonomous sea surface height and sea surface temperature observations from the Haiyang-2(HY-2)satellite fusion data,to establish an operational quasi-realtime three-dimensional(3D)temperature and salinity products over the Maritime Silk *** products feature a daily temporal resolution and a spatial resolution of 0.25°×0.25°and exhibit stability and *** have demonstrated the accuracy of the reconstructed thermohaline fields in capturing the 3D thermohaline variations through comprehensive statistical evaluations,after comparing them against Argo observations and ocean analysis data from *** results illustrate that the reconstructed fields effectively represent seasonal variations in oceanic subsurface structures,along with structural changes resulting from mesoscale processes,and the upper ocean’s responses to tropical ***,the incorporation of HY-2 satellite observations notably enhances the accuracy of temperature and salinity reconstructions in the Northwest Pacific Ocean and marginally improves salinity reconstruction accuracy in the North Indian Ocean when compared to the World Ocean Atlas 2018 monthly climatology thermohaline *** a result,the reconstructed product holds promise for providing quasi-real-time 3D temperature and salinity field information to facilitate fast decisionmaking during emergencies,and also offers foundational thermohaline fields for operational ocean reanalysis and forecasting *** contributions enhance the safety and stability of ocean subsurface activities and navigation.

关键词： HY-2 satellite observations subsurface structures reconstruction Maritime Silk Road operational thermohaline product

Answering reachability queries with ordered label constraints over labeled graphs

在线全文

学校读者我要写书评

暂无评论

Frontiers of Computer Science 2024年第1期18卷 105-117页

作者： Daoliang he Pingpeng yuan Hai JIN National Engineering Research Center for Big Data Technology and System Services Computing Technology and System LabCluster and Grid Computing LabSchool of Computer Science&TechnologyHuazhong University of Science and TechnologyWuhan 430074China

Reachability query plays a vital role in many graph analysis *** researches proposed many methods to efficiently answer reachability queries between vertex *** many real graphs are labeled graph,it highly demands Label-Constrained Reachability(LCR)query inwhich constraint includes a set of labels besides vertex *** researches proposed several methods for answering some LCR queries which require appearance of some labels specified in constraints in the *** that constraint may be a label set,query constraint may be ordered labels,namely OLCR(Ordered-Label-Constrained Reachability)queries which retrieve paths matching a sequence of ***,no solutions are available for ***,we propose DHL,a novel bloom filter based indexing technique for answering OLCR *** can be used to check reachability between vertex *** the answers are not no,then constrained DFS is ***,we employ DHL followed by performing constrained DFS to answer OLCR *** show that DHL has a bounded false positive rate,and it's powerful in saving indexing time and *** experiments on 10 real-life graphs and 12 synthetic graphs demonstrate that DHL achieves about 4.8-22.5 times smaller index space and 4.6-114 times less index construction time than two state-of-art techniques for LCR queries,while achieving comparable query response *** results also show that our algorithm can answer OLCR queries effectively.

关键词： graph ordered-label-constrained reachability partial index bloom filter query processing

Adhesive Contact of Elastic Solids with Self-Affine Fractal Rough Surfaces

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

Acta Mechanica Solida Sinica 2024年第2期37卷 265-270页

作者： Xuan-Ming Liang Shi-Wen Chen Si-he wang Zhen-yuan Gong Jun Feng Gang-Feng wang Department of Engineering Mechanics SVL and MMMLXi’an Jiaotong UniversityXi’an710049China OPPO Mobile Telecommunications Corporation Ltd. Dongguan523860China

The elastic adhesive contact of self-affine fractal rough surfaces against a rigid flat is simulated using the finite element method. An array of nonlinear springs, of which the force-separation law obeys the Lennard–Jones potential, is introduced to account for the interfacial adhesion. For fractal rough surfaces, the interfacial interaction is generally attractive for large mean gaps, but turns repulsive as the gap continuously shrinks. The interfacial interactions at the turning point corresponding to the spontaneous contact are shown for various surfaces. For relatively smooth surfaces, the probability density distributions of repulsion and attraction are nearly symmetric. However, for rougher surfaces, the simulation results suggest a uniform distribution for attraction but a monotonously decreasing distribution with a long tail for repulsion. The pull-off force rises with increasing ratio of the work of adhesion to the equilibrium distance, whereas decreases for solids with a higher elastic modulus and a larger surface roughness. The current study will be helpful for understanding the adhesion of various types of rough solids.

关键词： Fractal rough surfaces Adhesion Contact mechanics Lennard-Jones potential