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Search Results: 1 - 10 of 78329 matches for " Jianyun Chen "
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Probability Analysis for the Damage of Gravity Dam  [PDF]
Qiang Xu, Jing Li, Jianyun Chen
Engineering (ENG) , 2011, DOI: 10.4236/eng.2011.34036
Abstract: Damage reliability analysis is an emerging field of structural engineering which is very significant in structures of great importance like arch dams, large concrete gravity dams etc. The research objective is to design and construct an improved method for damage reliability analysis for concrete gravity dam. Firstly, pseudo excitation method and Mazar damage model were used to analyze how to calculate damage expected value excited by random seismic loading and deterministic static load on the condition that initial elastic modulus was deterministic. Moreover, response surface method was improved from the aspects of the regression of sample points, the selection of experimental points, the determined method of weight matrix and the calculation method of checking point respectively. Then, the above method was used to analyze guarantee rate of damage expected value excited by random seismic loading and deterministic static load on the condition that initial elastic modulus was random. Finally, a test example was given to verify and analyze the convergence and stability of this method. Compared with other conventional algorithm, this method has some strong points: this algorithm has good convergence and stability and greatly enhances calculation efficiency and the storage efficiency. From what has been analyzed, we find that damage expected value is insensitive to the randomness of initial elastic modulus so we can neglect the randomness of initial elastic modulus in some extent when we calculate damage expected value.
A Study on the Functional Reliability of Gravity Dam  [PDF]
Qiang Xu, Jianyun Chen, Jing Li
Energy and Power Engineering (EPE) , 2012, DOI: 10.4236/epe.2012.42009
Abstract: The research objective is to design and construct a method for functional reliability analysis of concrete gravity dam. Firstly, the pseudo excitation method was utilized to analyze to calculate the probabilistic characteristics of concrete gravity dam excited by random seismic loading. Meanwhile, the response surface method based on weighted regression was associated to that method to analyze functional reliability of concrete gravity dam. Eventually, a test example was given to verify and analyze the convergence and stability of this method.
A Parallel FEA Computing Kernel for Building Structures  [PDF]
Jin Duan, Yungui Li, Xiaoming Chen, Hu Qi, Jianyun Sun
Journal of Applied Mathematics and Physics (JAMP) , 2013, DOI: 10.4236/jamp.2013.16006
Abstract:

With the rapid development of high-rise buildings and long-span structures in the recent years, high performance com- putation (HPC) is becoming more and more important, sometimes even crucial, for the design and construction of com- plex building structures. To satisfy the engineering requirements of HPC, a parallel FEA computing kernel, which is designed typically for the analysis of complex building structures, will be presented and illustrated in this paper. This kernel program is based on the Intel Math Kernel Library (MKL) and coded by FORTRAN 2008 syntax, which is a parallel computer language. To improve the capability and efficiency of the computing kernel program, the parallel concepts of modern FORTRAN, such as elemental procedure, do concurrent, etc., have been applied extensively in coding and the famous PARDISO solver in MKL has been called to solve the Large-sparse system of linear equations. The ultimate objective of developing the computing kernel is to make the personal computer have the ability to analysis large building structures up to ten million degree of freedoms (DOFs). Up to now, the linear static analysis and dynamic analysis have been achieved while the nonlinear analysis, including geometric and material nonlinearity, has not been finished yet. Therefore, the numerical examples in this paper will be concentrated on demonstrating the validity and efficiency of the linear analysis and modal analysis for large FE models, while ignoring the verification of the nonlinear analysis capabilities.

Hybrid Post-Processing Procedure for Displacement-Based Plane Elements  [PDF]
Xiaoming Chen, Song Cen, Jianyun Sun, Yungui Li
Journal of Applied Mathematics and Physics (JAMP) , 2013, DOI: 10.4236/jamp.2013.16004
Abstract:

In the analysis of high-rise building, traditional displacement-based plane elements are often used to get the in-plane internal forces of the shear walls by stress integration. Limited by the singular problem produced by wall holes and the loss of precision induced by using differential method to derive strains, the displacement-based elements cannot always present accuracy enough for design. In this paper, the hybrid post-processing procedure based on the Hellinger-Reissner variational principle is used for improving the stress precision of two quadrilateral plane elements. In order to find the best stress field, three different forms are assumed for the displacement-based plane elements \"\" and \"\" with drilling DOF. Numerical results show that by using the proposed method, the accuracy of stress solutions of these two displacement-based plane elements can be improved.

A Multi Resolution Method for Detecting Defects in Fabric Images
Jianyun Ni,Jing Luo,Zaiping Chen,Enzeng Dong
Research Journal of Applied Sciences, Engineering and Technology , 2013,
Abstract: This study proposes a novel technique for detecting defects in fabric image based on the features extracted using a new multi resolution analysis tool called Digital Curvelet Transform. The direction features of curvelet coefficients and texture features based on GLCM of curvelet coefficients act as the feature-sets for a k-nearest neighbor classifier. The validation tests on the developed algorithms were performed with images from TILDA’s Textile Texture Database. A comparative study between the GLCM-based, wavelet-based and the curvelet-based techniques has also been included. The high accuracy achieved by the proposed method suggests an efficient solution for fabric defect. Furthermore, the algorithm has good robustness to white noise. Note that, this study is the first documented attempt to explore the possibilities of a new multi resolution analysis tool called digital Curvelet Transform to address the problem of fabric defect.
Necessity of Grammar Teaching
Jianyun Zhang
International Education Studies , 2009, DOI: 10.5539/ies.v2n2p184
Abstract: Grammar is often misunderstood in the language teaching field. The misconception lies in the view that grammar is a collection of arbitrary rules about static structures in the language. Further questionable claims are that the structures do not have to be thought, learners will acquire them on their own, or if the structures are taught, the lessons that ensue will be boring. This thesis on comparative approach tries to make a brief analysis of necessity of grammar teaching before it gives a relatively objective description of its function and significance in language teaching. It argues that, grammar teaching is necessary in language teaching.
Na+ Transport and Plant Salt Resistance at the Whole Plant Level
整株水平上Na+ 转运体与植物的抗盐性

Min Chen,Jianyun Peng,Baoshan Wang,
陈敏
,彭建云,王宝山

植物学报 , 2008,
Abstract: Plants can maintain Na+ homeostasis to increase salt resistance by several mechanisms, which include limiting Na+ influx, strengthening Na+ efflux, lessening Na+ transport to the shoot, distributing Na+ of shoots to particular parts (e.g., old leaves), secreting Na+ outside the leaves by a salt-secreting structure or transporting Na+ to the root by phloem recirculation. This paper introduces advances in research into the roles of Na+ transportation in salt resistance of plants at the whole plant level.
RESEARCH ON CONCRETE FAILURE PROCESS UNDER UNIAXIAL TENSION BASED ON STOCHASTIC DAMAGE MODEL
基于随机损伤模型的混凝土轴拉破坏过程研究

LIU Zhiguang,CHEN Jianyun,BAI Weifeng,
刘智光
,陈健云,白卫峰

岩石力学与工程学报 , 2009,
Abstract: 采用一维细观力学随机损伤模型,从材料加载过程中损伤能量耗散与应变能释放之间的能量平衡出发,对混凝土试件单轴拉伸破坏过程的稳定性进行分析并得到了破坏过程稳定开展的判定条件。利用这一条件确定了材料由均匀损伤过渡到局部损伤的临界状态,同时指出临界状态异于且滞后于峰值应力状态。临界状态后若为非稳定破坏将发生应力跌落,是材料脆性破坏的表现,若为稳定破坏则材料延性更为明显。理论分析结果表明,包含应力跌落的应力–应变软化不仅与材料力学性能的非均匀性有关,还与试件结构尺寸有关,具有明显的尺寸效应,不能视为单纯的材料属性。最后分别以材料极限应变服从Weibull分布和对数正态分布描述材料的非均匀性,对不同尺寸的混凝土试件轴拉破坏过程进行模拟,表明了所给出结论的合理性。
STATISTICAL DAMAGE MODEL OF CONCRETE UNDER UNIAXIAL TENSION CONSIDERING DYNAMIC STRAIN-RATE EFFECT
考虑动态应变率效应的混凝土单轴拉伸统计损伤模型

CHEN Jianyun,BAI Weifeng,
陈健云
,白卫峰

岩石力学与工程学报 , 2007,
Abstract: Based on the meso-scale damage mechanism of quasi-brittle materials,the damage can be generalized into two aspects,"the decrease of the effective cross-section"and"the degradation of the elastic modulus of the effective region corresponding to the effective cross-section",which can be represented by rupture and yield damage modes respectively. The essence of failure process is the continuum accumulation and evolution process of the two damage modes. The dynamic behavior behaved by dry concrete can be essentially attributed to the inertia effect itself,which leads to the change of the breakage form and the two damage evolution process of materials. Ignoring the effect of water viscosity,by the hypothesis that the damage evolution rule of material under different strain-rate cases obeys a certain similarity,an increment-format dynamic damage constitutive model under uniaxial tension is proposed. Comparison of the prediction results with experimental data shows that it can accurately reflect and predict the dynamic damage characteristics in the uniform damage phase for concrete under the constant or variable strain-rate cases. Combining with the examples,the dynamic damage mechanism of materials is discussed from the view points of effective stress,nominal stress and the energy absorption capability. Two characteristic states,the peak nominal stress state and the critical state when appears macro-crack are distinguished;and the latter is proposed as the final failure point in the constitutive model. Treated by this way,not only the ductibility of the uniform damage phase of materials can be considered adequately,but also the size effect of constitutive model during the local breakage phase can be avoided to consider.
REPLY TO "DISCUSSION ON ''''STUDY ON PHYSICAL MODEL OF COMPLETE FAILURE PROCESS OF QUASI-BRITTLE MATERIALS IN TENSION''''"
关于“对‘准脆性材料单轴拉伸破坏全过程物理模型研究’讨论”的回复

BAI Weifeng,CHEN Jianyun,
白卫峰
,陈健云

岩石力学与工程学报 , 2007,
Abstract: 1引言作者发表于《岩石力学与工程学报》2007年26卷第4期的"准脆性材料单轴拉伸破坏全过程物理模型研究"1](以下称原文)引起沈新普教授的讨论。非常感谢沈教授对拙作提出的宝贵意见,现就有关问题与沈教授商榷,并希望同各界同仁就工程材料损伤、破坏领域的问题展开积极的讨论。
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