检索结果-南通市图书馆

Structural Durability & Health Monitoring 2025年第1期19卷 25-54页

作者： Chao Zhang Shang-Xi Lai Hua-Ping Wang School of Civil engineering and mechanics Lanzhou UniversityLanzhou730000China Key laboratory of Special Functional Materials and Structural Design Ministry of EducationLanzhou UniversityLanzhou730000China

Modal parameters can accurately characterize the structural dynamic properties and assess the physical state of the ***,it is particularly signiﬁcant to identify the structural modal parameters according to the monitoring data information in the structural health monitoring(SHM)system,so as to provide a scientiﬁc basis for structural damage identiﬁcation and dynamic model modiﬁ*** view of this,this paper reviews methods for identifying structural modal parameters under environmental excitation and brieﬂy describes how to identify structural damages based on the derived modal *** paper primarily introduces data-driven modal parameter recognition methods(e.g.,time-domain,frequency-domain,and time-frequency-domain methods,etc.),brieﬂy describes damage identiﬁcation methods based on the variations of modal parameters(e.g.,natural frequency,modal shapes,and curvature modal shapes,etc.)and modal validation methods(e.g.,Stability Diagram and Modal Assurance Criterion,etc.).The current status of the application of artiﬁcial intelligence(AI)methods in the direction of modal parameter recognition and damage identiﬁcation is further *** on the pre-vious analysis,the main development trends of structural modal parameter recognition and damage identiﬁcation methods are given to provide scientiﬁc references for the optimized design and functional upgrading of SHM systems.

关键词： Structural health monitoring data information modal parameters damage identiﬁcation AI method

Fast Protection Strategy for DC Transmission Lines of MMC-based MT-HVDC Grid

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Electrical engineering 2021年第2期7卷 83-92页

作者： Sihua Wang Lijun Zhou Tian Wang Tianyu Chen Yu Wang College of Automation&Electrical engineering Lanzhou Jiaotong UniversityLanzhou 730070China rail transit Electrical Automation engineering laboratory of gansu province Lanzhou Jiaotong UniversityLanzhou 730070China

Multi-terminal high voltage DC(MT-HVDC)grid has broad application prospects in connecting different energy sources,asynchronous interconnection of power grids,remote load power supply,and other *** present,the key technologies that affect the development of MT-HVDC transmission system include swift fault identification and location in the DC line and its rapid *** fault monitoring relies on line communication,which cannot guarantee the rapidity and reliability of protection;moreover,it may even cause device damage.A fault identification scheme based on a single-terminal transient is presented in this *** scheme calculates the line inductance by using the rise rate of fault current at the initial stage of the fault,and determines the occurrence of the fault by comparing the observed line inductance with the set value,which lays a foundation for calculating the location of the fault point using distance protection.A simulation model on the PSCAD/EMTDC platform is built;the simulation example verifies that the proposed scheme can identify faults under dissimilar conditions while maintaining a low error level on the premise of no communication lines so as to meet the protection requirements of the MT-HVDC grid.

关键词： Multi-terminal high voltage DC(MT-HVDC)grid modular multilevel converter(MMC) DC circuit breaker(DCCB) bipolar short-circuit fault identification

Vibration Characteristics Analysis and Structure Optimization of Catenary Portal Structure on Four-Wire Bridge

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Structural Durability & Health Monitoring 2022年第4期16卷 361-382页

作者： Sihua Wang Xujie Li School of Automation&Electrical engineering Lanzhou Jiaotong UniversityLanzhou730070China rail transit Electrical Automation engineering laboratory of gansu province(Lanzhou Jiaotong University) Lanzhou730070China

The portal structure is the support equipment in the catenary,which bears the load of contact suspension and support *** practical work,with the change of external forces,the support equipment bears complex and changeable loads,so it has higher requirements for its reliability and *** order to study the dynamic characteristics of catenary portal structure on continuous beam of four-way bridge,taking the catenary portal structure on Dshaping four-way bridge as the research object,the portal structure simulation model of bridgenetwork integration was established in Midas *** maximum point of deformation and stress was determined by finite element analysis of catenary hard span equipment,and the frequency and mode of natural vibration of hard span were obtained by modal ***,through the field dynamic stress acquisition test,combined with the results of finite element analysis,the fault location is determined,and the vibration characteristics are ***,based on the results of modal analysis and vibration analysis,the method that the vibration of portal structure beam is affected by structural stiffness and vibration frequency amplitude is *** torsional vibration of the portal structure beam was suppressed by increasing the stiffness of the beam and reducing the vibration conduction between the trolley and the beam,and the hard cross beam was optimized by strengthening the hanging column and the connecting beam and adding diagonal support between the pillar and the portal structure *** comparing the values of shear,bending moment,displacement and dynamic stress on the hard span before and after optimization,the amplitude peak after structural optimization is reduced by about 25%,and the application of oblique support and reinforcement of the beam can significantly improve the portal structure vibration.

关键词： Catenary portal structure vibration analysis modal analysis structural optimization

application of a vertex chain operation algorithm on topological analysis of three-dimensional fractured rock masses

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Frontiers of Structural and Civil engineering 2017年第2期11卷 187-208页

作者： Zixin ZHANG Jia WU Xin HUANG Department of Geotechnical engineering School of Civil Engineering Tongji University Shanghai 200092 China Key laboratory of Geotechnical and Underground engineering of Ministry of Education Tongji University State Key laboratory for Geomechanies and Deep Underground engineering Xuzhou 221008 China a shanghai Tunnel engineering & rail transit Design and Research Institute Shanghai 200235 China

Identifying the morphology of rock blocks is vital to accurate modelling of rock mass structures. This paper applies the concepts of directed edges and vertex chain operations which are typical for block tracing approach to block assembling approach to construct the structure of three-dimensional fractured rock masses. Polygon subtraction and union algorithms that rely merely on vertex chain operation are proposed, which allow a fast and convenient construction of complex faces/loops. Apart from its robustness in dealing with finite discontinuities and complex geometries, the advantages of the current methodology in tackling some challenging issues associated with the morphological analysis of rock blocks are addressed. In particular, the identification of complex blocks with interior voids such as cavity, pit and toms can be readily achieved based on the number and the type of loops. The improved morphology visualization approach can benefit the pre-processing stage when analyzing the stability of rock masses subject to various engineering impacts using the block theory and the discrete element method.

关键词： morphology block assembling vertex operation discontinuities

A modified fractional-order thermo-viscoelastic model and its application to a polymer micro-rod heated by a moving heat source

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) 2022年第4期43卷 507-522页

作者： Wei PENG Like CHEN Tianhu HE Key laboratory of Disaster Prevention and Mitigation in Civil engineering of gansu province Lanzhou University of TechnologyLanzhou 730050China School of Civil engineering and mechanics Lanzhou UniversityLanzhou 730000China School of Science Lanzhou University of TechnologyLanzhou 730050China

Classical thermo-viscoelastic models may be challenged to predict the precise thermo-mechanical behavior of viscoelastic materials without considering the memorydependent ***,with the miniaturization of devices,the size-dependent effect on elastic deformation is becoming more and more *** capture the memory-dependent effect and the size-dependent effect,the present study aims at developing a modified fractional-order thermo-viscoelastic coupling model at the microscale to account for two fundamentally distinct fractional-order models which govern the memory-dependent features of thermal conduction and stress-strain relation,***,the modified theory is used to study the dynamic response of a polymer micro-rod heated by a moving heat *** governing equations are obtained and solved by the Laplace transform *** calculation,the effects of the fractional-order parameter,the fractional-order strain parameter,the mechanical relaxation parameter,and the nonlocal parameter on the variations of the considered variables are analyzed and discussed in detail.

关键词： size-dependent effect fractional-order strain fractional-order thermal conduction generalized thermo-viscoelasticity moving heat source

Electrocaloric effect in ferroelectric materials:From phase field to first-principles based effective Hamiltonian modeling

在线全文

学校读者我要写书评

暂无评论

Materials Reports(Energy) 2021年第3期1卷 34-63页

作者： Jingtong Zhang Xu Hou Yajun Zhang Gang Tang Jie Wang Department of engineering mechanics School of Aeronautics and AstronauticsZhejiang UniversityHangzhou310027PR China Department of mechanics and engineering Sciences College of Civil Engineering and MechanicsLanzhou UniversityLanzhouGansu730000PR China Theoretical Materials Physics Q-MATCESAMUniversity of LiegeB-4000LiegeBelgium Key laboratory of Soft Machines and Smart Devices of Zhejiang province Zhejiang UniversityHangzhou310027PR China

Electrocaloric effect(ECE)of ferroelectrics has attracted considerable interest due to its potential application in environmentally friendly solid-state *** discovery of giant ECE in ferroelectric thin films has greatly renewed the research activities and significantly stimulated experimental and theoretical *** this review,the recent progress on the theoretical modeling of ECE in ferroelectric and antiferroelectric materials are introduced,which mainly focuses on the phase field modeling and first-principles based effective Hamiltonian *** firstly provide the theoretical foundation and technique details for each *** a comprehensive review on the progress in the application of two methods and the strategies to tune the ECE are ***,we outline the practical procedure on the development of multi-scale computational method without experiemtal parameters for the screening of optimized electrocaloric materials.

关键词： Electrocaloric effect Ferroelectric materials Phase field simulation Machine learning models First-principles based effective Hamiltonian modeling

application of a p-version curved C^(1)finite element based on the nonlocal Kirchhoff plate theory to the vibration analysis of irregularly shaped nanoplates

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2023年第10期66卷 3025-3047页

作者： XIANG Wei NI Hua TIAN YiFeng WU Yang LIU Bo School of Mechanical engineering Southwest Jiaotong UniversityChengdu 610031China Technology and Equipment of rail transit Operation and Maintenance Key laboratory of Sichuan province Chengdu 610031China Southwest China Research Institute of Electronic Equipment Chengdu 610036China CAEP Software Center for High Performance Numerical Simulation Beijing 100088China Institute of Applied Physics and Computational Mathematics Beijing 100088China The Solid mechanics Research Centre Beihang University(BUAA)Beijing 100191China

Nanoplates have been widely used as elementary components for ultrasensitive and ultrafine resolution applications in the field of nano-electro-mechanical systems because of their potentially remarkable mechanical *** accurate analysis of their mechanical behavior is currently of particular interest in the function design and reliability analysis of nano-scaled *** examine the size-dependent bending and vibration behavior of nanoplates with curvilinear and irregular shapes,a new p-version curved C^(1)finite element is formulated in the framework of the nonlocal Kirchhoff plate *** newly developed element not only enables an accurate geometry representation and easy mesh generation of curvilinear domains but also overcomes the difficulty of imposing C^(1)conformity required by the nonlocal Kirchhoff plate model,particularly on the curvilinear inter-element *** examples show that this element can produce an exponential rate of convergence even when curved elements are used in the domain *** numerical results are presented for nanoplates with various geometric shapes,including rectangular,circular,elliptic,annular,and *** high accuracy of the present element is verified by comparing the obtained results with analytical and numerical results in the ***,a comprehensive parametric analysis is conducted to investigate the influences of nonlocal parameters,plate dimensions,and boundary conditions on the nonlocal behavior of *** present element can be envisaged to allow large-scale mechanical simulations of nanoplates,with a guarantee of accuracy and efficiency.

关键词： nanoplates nonlocal theory p-version finite element method C^(1)conformity irregular shape

Optimization of anchorage support parameters for soft rock tunnel based on displacement control theory

在线全文

学校读者我要写书评

暂无评论

Journal of Mountain Science 2023年第7期20卷 2076-2092页

作者： LI Gan MA Wei-bin YU Chang-yi TAO Zhi-gang WANG Feng-nian School of Civil&Environmental engineering and Geography Science Rock mechanics Research InstituteNingbo UniversityNingbo 315000China railway engineering Research Institute China Academy of Railway Sciences Corporation LimitedBeijing 100081China CCCC First Harbor engineering Company Co.Ltd.Tianjin 300461 CCCC-Tianjin Port engineering Institute Co.Ltd.Tianjin 300222 State Key laboratory for Geomechanics&Deep Underground engineering Beijing 100083China Shanxi Transportation Technology Research and Development Co. LTDTaiyuan 030032China

In the construction of a soft rock tunnel,it is critical to accurately estimate the pre-stressed anchor support parameters for surrounding rock reinforcement;otherwise,engineering disasters may *** paper presents a support parameter selection method that aims to allow deformation as a control objective,which was applied to the tunnel located in Muzailing Highway,Min County,Dingxi City,gansu province,*** theoretical analysis,we have identified five factors that influence pre-stressing *** selection of mechanical parameters for the rock mass was carried out using an inverse analysis *** with the measured data,the maximum displacement error of the numerical simulation results was only 0.07 *** length of anchor cable,circumferential spacing of anchor cable,longitudinal spacing,and pre-stress index are adopted as the input parameters for the support vector machine neural network model based on particle swarm optimization(PSO-LSSVM).Besides,the vault subsidence and the maximum deformation of surrounding rock are considered as output values(performance indices).The goodness of fit between the predicted values and the simulated values exceeds ***,all support parameters within the acceptable deformation range are *** optimal support variables are derived by considering the construction cost and *** field application results show that it is feasible to construct the sample database utilizing the numerical simulation approach by taking the displacement as the control target and using the neural network to specify the appropriate support parameters.

关键词： Displacement control theory Anchorage support parameters Numerical simulation PSOLSSVM Tunnel construction

An improvement of frozen-image model and its application in a HTS levitation system

在线全文

学校读者我要写书评

暂无评论

Theoretical & Applied mechanics Letters 2011年第3期1卷 8-12页

作者： Jun Zhou,Xingyi Zhang,and Youhe Zhou~(a)) Key laboratory of mechanics on Western Disaster and Environment(Ministry of Education of China), and Department of mechanics and engineering Science,College of Civil engineering and mechanics, Lanzhou University,Lanzhou 730000,China Key laboratory of mechanics on Western Disaster and Environment (Ministry of Education of China) and Department of Mechanics and Engineering Science College of Civil Engineering and Mechanics Lanzhou University Lanzhou 730000 China

This paper mainly reports an improvement of frozen-image model which can qualitatively describe the influence of lateral moving speed on vertical force in a HTS levitation system under lateral movement with field-cooling *** model is improved by introducing a dipole which represents the influence of lateral moving speed and modifying the rule of diamagnetic dipole based on frozen-image *** vertical and lateral forces that are obtained by this improved model agree with the previous measurements *** model can also describe the effect of finite scale of superconductor sample in a levitation system.

关键词： frozen-image model magnetic dipole moving speed cooling height levitation supercon-ductivity

Physico-mechanical properties of granite after cyclic thermal shock

在线全文

学校读者我要写书评

暂无评论

Journal of Rock mechanics and Geotechnical engineering 2020年第4期12卷 693-706页

作者： Peiyang Yu Peng-Zhi Pan Guangliang Feng Zhenhua Wu Shankun Zhao State Key laboratory of Geomechanics and Geotechnical engineering Institute of Rock and Soil MechanicsChinese Academy of SciencesWuhan430071China University of Chinese Academy of Sciences Beijing100049China Key laboratory of Ministry of Education on Safe Mining of Deep Metal Mines Northeastern UniversityShenyang110819China State Key laboratory of Coal Resources High Efficient Mining and Clean Utilization China Coal Research InstituteBeijing100013China

Understanding rock mechanical behaviors after thermal shock is critically important for practical engineering *** this context,physico-mechanical properties of Beishan granite,gansu province,China after cyclic thermal shock were studied using digital image correlation(DIC),acoustic emission(AE)monitoring,and microscopic *** results show that the peak strength and elastic modulus decreased gradually with increase in thermal shock ***,the above two parameters showed no further changes after 10 thermal shock *** loading stress ratio(*** ratio of the current loading stress level to the peak stress in this state)corresponding to the occurrence of the uneven principal strain field and the local strain concentration zone on the surface of the granite specimen decreased with increase in thermal shock *** transformation forms of the standard deviation curves of the surface principal strain were *** granite with fewer thermal shock cycles(*** more than 2 cycles),the standard deviation curves exhibited approximately exponential growth in exponential *** increase in thermal shock cycle,the S-shaped curve was *** 10 thermal shock cycles,an approximate ladder-shaped curve was *** is displayed that AE activity was mainly concentrated around the peak strength zone of the granite specimen when the rock samples underwent fewer thermal shock *** increase in thermal shock cycle,AE activity could occur at low loading stress *** observation further confirmed these scenarios,which showed that more microcracks were induced with increase in thermal shock *** number of induced microcracks at the edge location of the granite specimen was significantly larger than that at the interior ***,a continuum damage model was proposed to describe the damage evolution of the granite specimen after cyclic thermal shock during loading.

关键词： Beishan granite Cyclic thermal shock Digital image correlation(DIC) Acoustic emission(AE) Physico-mechanical properties Continuum damage model