检索结果-南通市图书馆

Assessment of marine pollution in Daya Bay, South china: Nutrients, heavy metals and persistent organic pollutants

在线全文

学校读者我要写书评

暂无评论

Acta Geochimica 2006年第S1期 166-166页

作者： Yaowen QIU1,2. Gan ZHANG1, Wen YAN2. Liangsheng ZHU2. Xiangdong LI3 1 State Key Laboratory of Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, china 2.Key Laboratory of Tropic Marine Environmental Dynamics, South china Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, china 3 department of civil and structural engineering, hong kong polytechnic university/hong kong, china

THE USE OF VISCO-ELASTOPLASTIC DAMAGE CONSTITUTIVE MODEL TO SIMULATE NONLINEAR BEHAVIOR OF CONCRETE

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Acta Mechanica Solida Sinica 2011年第5期24卷 411-428页

作者： Jun Liu Gao Lin Bing Fu hong Zhong State Key Laboratory of Coastal and Offshore Engineering Dalian University of Technology Dalian 116023 China department of civil and {2. engineering The Hong Kong Polytechnic University Hong Kong China

A visco-elastoplastic damage constitutive model is proposed for simulating non-linear behavior of concrete. Based on traditional plastic theory, the irreversible deformation is simulated in effective stress space. In order to reflect different stiffness degradation mechanism of concrete under tensile and compressive loading conditions, both tensile and compressive damage variables are introduced, and then on the basis of energy release rate, the model is firmly derived within the concept of irreversible thermodynamics. The rate-dependent model is considered by introducing viscous regularization into the inelastic strain and damage variable, and combined with an additional elastic condition. Fully implicit backward-Euler algorithm is used to perform constitutive integration. Results of numerical examples using the proposed model agree well with test results for specimens under uniaxial tension and compression, biaxial loading and triaxial loading. Failure processes of single-edge-notched （SEN） beam and double-edge-notched （DEN） specimen are also simulated to further validate the proposed model.

关键词： damage rate-dependent plasticity thermodynamics energy release rate nonlinear behavior concrete

在线全文

学校读者我要写书评

暂无评论

时变结构可靠度预测方法探讨

武汉工业学院学报 2004年第1期23卷 51-54页

作者：谢桂华李继祥耿树勇刘建军长江大学土木与建筑系湖北荆州434023 武汉工业学院土木工程系湖北武汉430023

时变结构在剩余使用寿命内的可靠度预测,是以结构在检测时刻的状态和所处环境为基础,一般采用概率模型和离散手段两种方法。本文概述了离散抗力求服役期结构可靠度的方法;基于已有结构抗力衰减模型和剩余使用寿命期内可变荷载计算模型... 详细信息

时变结构在剩余使用寿命内的可靠度预测,是以结构在检测时刻的状态和所处环境为基础,一般采用概率模型和离散手段两种方法。本文概述了离散抗力求服役期结构可靠度的方法;基于已有结构抗力衰减模型和剩余使用寿命期内可变荷载计算模型的既有成果,考虑结构抗力的时变特性,提出一种新的时变可靠度计算方法。实例表明:该方法计算简单,结果可信。

关键词：时变结构可靠度预测方法

Realizing high-performance Zn-ion batteries by a reduced graphene oxide block layer at room and low temperatures

在线全文

学校读者我要写书评

暂无评论

Journal of Energy Chemistry 2020年第4期29卷 1-7页

作者： Jian-Qiu Huang Xiuyi Lin hong Tan Xiaoqiong Du Biao Zhang department of Applied Physics The Hong Kong Polytechnic UniversityHong KongChina

Rechargeable aqueous Zn-ion batteries (ZIBs) have attracted great attention due to their costeffectiveness,high safety,and environmental ***,some issues associated with poor structural instability of cathode materials and fast self-discharge hinder the further development of ***,a new configuration is introduced by placing a reduced graphene oxide film as a block layer between the separator and the V2.5·nH2. *** layer prevents the free diffusion of dissolved active materials to the anode and facilitates the transport of Zn ion and electrons,largely improving the cyclic stability and alleviating the ***,the optimized battery delivers a remarkable capacity of 191 mAh g^-1 after 500 cycles at 2.A g^-***,a high capacity of 106 mAh g^-1 is achieved after 100 cycles at-2.℃.The strategy proposed is expected to be applicable to other electrode systems,thus offering a new approach to circumvent the critical challenges facing aqueous batteries.

关键词： Block layer Dissolution Self-discharge Low temperatures Aqueous Zn-ion batteries

在线全文

学校读者我要写书评

暂无评论

计算结构可靠度的JC法改进方法

武汉工业学院学报 2004年第1期23卷 48-50页

作者：李继祥谢桂华耿树勇刘建军武汉工业学院土木工程系湖北武汉430023 长江大学土木与建筑系湖北荆州434023

基于JC法求解结构可靠度的思想,提出一种新的计算方法。借助JC法中验算点的概念和可靠指标的几何意义,通过确定可靠指标的迭代初始值,改进可靠指标的求解过程,克服了JC法求解结构可靠度时可能存在的迭代不收敛的情况,达到求解稳定和收... 详细信息

基于JC法求解结构可靠度的思想,提出一种新的计算方法。借助JC法中验算点的概念和可靠指标的几何意义,通过确定可靠指标的迭代初始值,改进可靠指标的求解过程,克服了JC法求解结构可靠度时可能存在的迭代不收敛的情况,达到求解稳定和收敛速度快的目的。通过算例表明,该法计算效率较好,结果可信。

关键词： JC法迭代验算点可靠指标

Comparative study on pullout behaviour of pressure grouted soil nails from field and laboratory tests

在线全文

学校读者我要写书评

暂无评论

Journal of Central South university 2013年第8期20卷 2285-2292页

作者： hong Cheng-yu YIN Jian-hua PEI Hua-fu department of civil {2. Shantou University Shantou 515063 China department of civil and Environmental {2. The Hong Kong Polytechnic University Hung Hom Kowloon Hong Kong China

Pullout resistance of a soil nail is a critical parameter in design and analysis for geotechnical engineers. Due to the complexity of field conditions, the pullout behaviour of cement grouted soil nail in field is not well investigated. In this work, a number of field pullout tests of pressure grouted soil nails were conducted to estimate the pullout resistance of soil nails. The effective bond lengths of field soil nails were accurately controlled by a new grouting packer system. Typical field test results and the related comparison with typical laboratory test results reveal that the apparent coefficient of friction （ACF） decreases with the increase of overburden soil pressure when grouting pressure is constant, but increases almost linearly with the increase of grouting pressure when overburden pressure （soil depth） is unchanged. Water contents of soil samples at soil nail surfaces show obvious reductions compared with the results of soil samples from drillholes. After soil nails were completely pulled out of the ground, surface conditions of the soil nails and surrounding soil were examined. It is found that the water content values of the soil at the soil/nail interfaces decrease substantially compared with those of soil samples extracted from drillholes. In addition, all soil nails expand significantly in the diametrical direction after being pulled out of ground, indicating that the pressurized cement grout compacts the soil and penetrates into soil voids, leading to a corresponding shift of failure surface into surrounding soil mass significantly.

关键词： soil nail apparent coefficient of friction overburden soil pressure grouting pressure

THE ANALYTICAL SOLUTION FOR SEDIMENT REACTION AND DIFFUSION EQUATION WITH GENERALIZED INITIAL-BOUNDARY CONDITIONS

在线全文

学校读者我要写书评

暂无评论

Applied Mathematics and Mechanics(English Edition) 2001年第4期22卷 404-408页

作者： XIONG Yue-shan(熊岳山) Wai Wing-hong(韦永康) department of Computer Science National University of Science and Technology Changsha 410073 P R China Department of Civil and Structural Engineering The Hong Kong Polytechnic University Hung Hom Kowloon Hong Kong P R China

The sediment reaction and diffusion equation,with generalized initial mid boundary condition is studied. By using Laplace transform and Jordan lemma, an analytical solution is got,,which is an extension of analytical solution provided by Cheng Kwokming James ( only diffusion was considered in analytical solution of Cheng). Some problems arisen in the computation of analytical solution formula are also analysed.

关键词： sediment reaction diffusion analytical solution

structural Stability, Electronic and Magnetic Properties of O-doped Monolayer C_2.

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of structural Chemistry 2019年第1期38卷 76-82,3页

作者： CHEN Ying LIU Guang-Hua LI Yi-Peng kong Long-Juan LIU Peng-Fei department of Physics Tianjin Polytechnic University Institute of Physics Chinese Academy of Sciences Institute of High Energy Physics Chinese Academy of Sciences Dongguan Institute of Neutron Science

Based on the first-principles of density functional theory, the structural stability,electronic and magnetic properties of the O-doped monolayer C_2. are investigated. In details, the lattice parameters, band structures, density of states and phonon dispersions of O-doped monolayer C_2. are obtained and analyzed. Our results show that the introduction of oxygen dopants can cause a significant local lattice distortion. The band structure indicates that monolayer C_2. is a semiconductor with a direct band gap of 1.631 eV. The electronic properties of monolayer C_2. can be regulated by oxygen dopant atoms with different numbers. However, doping nonmetal oxygen element in monolayer C_2. does not affect its magnetic properties. In other words, the pure and O-doped systems are all nonmagnetic. The phonon dispersions of all the O-doped cases are found to have not any imaginary frequencies, which indicates that the structures of these O-doped systems have good structural stability.

关键词： O-doping electronic properties magnetic properties structural stability

在线全文

学校读者我要写书评

暂无评论

识别结构模态阻尼比的一种新方法

土木工程学报 2002年第6期35卷 20-23,31页

作者：黄方林何旭辉陈政清高赞明倪一清中南大学香港理工大学

提出一种新的由结构自由振动响应识别结构阻尼比的方法。对于单自由度振动系统 ,推导出响应历程与时轴所围各面积之间的确定性关系后 ,利用各面积之间的关系来确定自由衰减振动的阻尼比系数。与传统的对数衰减率法比较 ,它具有抗噪声干... 详细信息

提出一种新的由结构自由振动响应识别结构阻尼比的方法。对于单自由度振动系统 ,推导出响应历程与时轴所围各面积之间的确定性关系后 ,利用各面积之间的关系来确定自由衰减振动的阻尼比系数。与传统的对数衰减率法比较 ,它具有抗噪声干扰能力强、精度高、稳定性好及简便实用等特点。对于多自由度振动系统 ,先将结构上某测点的自由振动响应表达为一理论解析式x (t) ,以eat相乘x (t) ,预给a初值范围 ,通过牛顿二分法(或黄金分割法 )搜索a值 ,直至eatx (t)做等幅振荡 ,则该阶模态的各模态参数得以确定。从总响应中扣除该阶模态对总响应的贡献后 ,重复这一过程 ,则可识别出响应信号中各阶模态的模态阻尼比。仿真计算与岳阳洞庭湖斜拉桥拉索实测试验结果表明了本文方法的有效性和实用性。

关键词：模态阻尼比参数识别斜拉桥拉索