检索结果-南通市图书馆

3D fracture modelling and limit state analysis of prestressed composite concrete pipes

在线全文

学校读者我要写书评

暂无评论

Frontiers of Structural and Civil Engineering 2019年第1期13卷 165-175页

作者： Pengfei HE yang shen Yun GU Pangyong shen School of Aerospace Engineering and Applied Mechanics Tongji UniversityShanghai 200092China Shanghai SMI Engineering Project Management Co. Ltd.Shanghai 201103China

In this manuscript,we study fracture of prestressed cylindrical concrete *** concrete pipes play a major role in tunneling and underground *** structure is modelled fully in 3D using three-dimensional continuum elements for the concrete structure which beam elements are employed to model the *** allows the method to capture important phenomena compared to a pure shell model of concrete.A continuous approach to fracture is chosen when concrete is subjected to compressive loading while a combined continuous-discrete fracture method is employed in *** model is validated through comparisons with experimental data.

关键词： cylindrical concrete structures limit state analysis 3D fracture modelling prestressed composite pipes reinforced concrete three-point bending test

High thermal conductivity dielectric polymers show record high capacitive performance at high temperatures

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

National Science Review 2023年第11期10卷 85-86页

作者： yang shen Ce-Wen Nan Tsinghua University State Key Laboratory of New Ceramics and Fine Processing School of Materials Science and Engineering

Electrostatic capacitors are the most widely used components in modern electrical and electronic systems ranging from integrated circuits, electrical energy storage and pulsed power *** are the preferred dielectrics for electrostatic capacitors owing to their unique self-healing ability, high breakdown strength and ease of processing[1,2]. However, as the operating temperature increases, dielectric polymers exhibit substantially increased conduction loss,

关键词：

H_(2)/H_(∞) Control for Stochastic Jump-Diffusion Systems with Markovian Switching

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Systems Science & Complexity 2021年第3期34卷 924-954页

作者： WANG Meijiao MENG Qingxin shen yang Business School University of Shanghai for Science and TechnologyShanghai 200093China Department of Mathematical Sciences Huzhou UniversityZhejiang 313000China School of Risk&Actuarial Studies University of New South WalesSydneyNSW 2052Australia

In this paper, a stochastic H2/H∞ control problem is investigated for Poisson jumpdiffusion systems with Markovian switching, which are driven by a Brownian motion and a Poisson random measure with the system parameters modulated by a continuous-time finite-state Markov chain.A stochastic jump bounded real lemma is proved, which reveals that the norm of the perturbation operator below a given threshold is equivalent to the existence of a global solution to a parameterized system of Riccati type differential equations. This result enables the authors to obtain sufficient and necessary conditions for the existence of H2/H∞ control in terms of two sets of interconnected systems of Riccati type differential equations.

关键词： H_(2)/H_(∞)control jump bounded real lemma jump-diffusion systems Markovian switching system of Riccati type differential equations

Boundedness of the period maps and global Torelli theorem

在线全文

学校读者我要写书评

暂无评论

Science China Mathematics 2017年第6期60卷 1029-1046页

作者： LIU KeFeng shen yang Center of Mathematical Sciences Zhejiang University Department of Mathematics University of California at Los Angeles

Recently, we proved the Griffiths conjecture on the boundedness of the period maps, and then used it to prove global Torelli theorem on the Torelli space under certain natural conditions. This paper serves as a review... 详细信息

关键词： moduli spaces period maps affine structures Hodge metric completion global Torelli theorem

景观格局对生态系统服务空间分异特征的影响——以东营市为例

在线全文

学校读者我要写书评

暂无评论

东北林业大学学报 2025年第2期53卷 86-96页

作者：房子钰丁宁冯恒栋沈阳张达延边大学吉林省·珲春市133300

以山东省东营市全域为研究区域,以2000、2010、2020年,来源于地理空间数据云(https://***/)的Landsat遥感影像数据、资源环境科学数据平台(https://***/)的中国多时期土地利用遥感监测数据集(CNLUCC)、《东营市统计年鉴》的东营市社会... 详细信息

以山东省东营市全域为研究区域,以2000、2010、2020年,来源于地理空间数据云(https://***/)的Landsat遥感影像数据、资源环境科学数据平台(https://***/)的中国多时期土地利用遥感监测数据集(CNLUCC)、《东营市统计年鉴》的东营市社会经济统计数据为数据源;应用ENVI 5.3软件对卫星影像数据进行预处理,将预处理后的数据采用ArcGIS 10.2软件进行目视评价分类,根据东营市实际情况将土地利用和土地覆盖类型划分为农田、湿地、水体、建设用地、草地共5类;综合考虑景观的面积度量、形状选择、多样性程度、离散程度4个方面,设计斑块密度、最大斑块指数、景观形状指数、分离度指数、香农多样性指数、散布与并列指数6个景观指标,评价东营市的景观格局特征;以生态系统服务价值为评价指标、景观格局特征(景观格局指数)为影响因素,采用价值转移法依据修正的价值当量系数计算东营市生态系统服务价值,利用普通最小二乘法(OLS)模型、地理加权回归模型(GWR)分析东营市景观格局对生态系统服务价值空间分异特征的影响。结果表明:①2000—2020年,东营市农田、建设用地、水体面积增加,湿地、草地面积减少。②2000—2020年,东营市整体景观特征的指数变化,最大斑块指数、景观形状指数增加,而斑块密度、分离度指数、散布与并列指数、香农多样性指数减少,斑块类型特征指数变化各异。③2000—2020年,东营市生态系统服务价值总体增加了约1.95亿元,空间上生态系统服务价值呈现北部和东部高、西部和南部低的特点。④2000—2020年,斑块密度对生态系统服务价值总体为负向影响、散布与并列指数对生态系统服务价值仅具有正向影响(影响系数范围为0.04~0.45)、分离度指数和香农多样性指数都对生态系统服务价值整体具有正向影响。

关键词：景观格局生态系统服务价值空间分异特征东营市

Transient Characteristics and Accommodative Current Limiting Strategy for Bidirectional Interlinking Converters in Hybrid AC/DC Microgrids

在线全文

学校读者我要写书评

暂无评论

CSEE Journal of Power and Energy Systems 2024年第4期10卷 1575-1588页

作者： Xia shen Zhikang Shuai Wen Huang Chao shen yang shen Z.John shen College of Electrical and Information Engineering Hunan UniversityChangsha 410082China Department of Electrical and Computer Engineering Illinois Institute of TechnologyChicagoIL 60616 USA

Bidirectional interlinking converter(BIC)is the core equipment in a hybrid AC/DC microgrid connected between AC and DC ***,the variety of control modes and flexible bidirectional power flow complicate the influence of AC faults on BIC itself and on DC sub-grid,which potentially threaten both converter safety and system *** study first investigates AC fault influence on the BIC and DC bus voltage under different BIC control modes and different pre-fault operation states,by developing a mathematical model and equivalent sequence ***,based on the analysis results,a general accommodative current limiting strategy is proposed for BIC without limitations to specific mode or operation *** amplitude is predicted and constrained according to the critical requirements to protect the BIC and relieving the AC fault influence on the DC bus *** with conventional methods,potential current limit failure and distortions under asymmetric faults can also be ***,experiments verify feasibility of the proposed method.

关键词： Bidirectional interlinking converter current limiting fault characteristic hybrid AC/DC microgrid variation/oscillation of DC bus voltage

A jamming method against bistatic SAR based on modulation theory

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Systems Engineering and Electronics 2019年第3期30卷 504-510页

作者： RAN Jinhe LI Xiuhe shen yang Electronic Countermeasure Institute National University of Defense Technology

This paper focuses on the jamming problem of bistatic synthetic aperture radar (BiSAR), and a jamming method against BiSAR based on modulation theory is proposed. The proposed jamming method modulates the BiSAR signal with the cosinusoidal phase to generate multi-false targets in range, and further rotates the jammer to generate multi-false targets in azimuth. The range multi-false targets and azimuth multi-false targets form the two-dimensional cover jamming or deception jamming, which can protect the important targets efficiently. The number of false targets, the interval of false targets, and the jamming square can be adjusted flexibly by setting different range jamming parameters and azimuth jamming parameters. The jamming performance and the choosing criteria of jamming parameters are also discussed. Finally, the simulated data verify the effectiveness of the jamming method.

关键词： bistatic synthetic aperture radar (BiSAR) cosinusoidal phase cover jamming micro-motion modulation

A grading parameter for evaluating the grading-dependence of the shear stiffness of granular aggregates

在线全文

学校读者我要写书评

暂无评论

Particuology 2018年第1期16卷 193-198页

作者： Yifei Sun yang shen Chen Chen Key Laboratory of Ministry of Education for Ceomechanics and Embankment Engineering Jiangsu Research Center for Ceotechnical Engineering Technology Hohai University Nanjing 210098 China

To capture the grading-dependence of the shear stiffness of heterogeneous granular aggregates, a new grading parameter that considered the size distribution of the entire aggregates was developed. Both the coefficient of uniformity and median particle size decreased with increasing the grading parameter. A general increase of the shear stiffness with increasing the grading parameter was observed. Compari- son with experimental results revealed that the proposed grading parameter had a stronger correlation with the material constants of Hardin＇s stiffness formula than the coefficient of uniformity, which is a traditional grading parameter.

关键词： Shear stiffness Grading Coefficient of uniformity Particle size

Fracture model for the prediction of the electrical percolation threshold in CNTs/Polymer composites

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 2018年第1期12卷 125-136页

作者： yang shen Pengfei HE Xiaoying ZHUANG School of Aerospace Engineering and Applied Mechanics Tongji University Shanghai China Department of Geotechnical Engineering College of Civil Engineering Tongji University Shanghai China Institute of Continuum Mechanics Leibniz-Universitat Hannover Germany State Key Laboratory for Disaster Reduction in Civil Engineering Tongji University Shanghai China

In this paper, we propose a 3D stochastic model to predict the percolation threshold and the effective electric conductivity of CNTs/Polymer composites. We consider the tunneling effect in our model so that the unrealistic interpenetration can be avoided in the identification of the conductive paths between the CNTs inside the polymer. The results are shown to be in good agreement with reported experimental data.

关键词： electrical percolation CNTs/Polymer composites fracture model electric conductivity tunnelling effects