Numerical Simulation of the Flat Ribbon Wound Explosion Containment Vessels Subjected to Internal Blast Loading

In order to constitute engineering design methods of the flat ribbon wound explosion containment vessels, the dynamic response of such vessels subjected to internal explosion loading is simulated using LS-DYNA3D. Three winding angles, 10°, 15°and 20°, are considered. It is shown that among ribbon vessels investigated, the center displacement of outermost ribbons of the vessel with 10°winding angle is the smallest under the same blast loading. The response of vessels loaded in inner core is local. From the center of the cylindrical shell to the bottom cover, the maximum strain gradually decreases. The ribbons are subjected to tension in the length direction and compression in the width direction. Blasting shock energy concentrates on where is close to center section of blasting. For comparison, numerical simulation of a monobloc thick-walled explosion containment vessel is also investigated. It can be found that the biggest deformation of the flat ribbon wound explosion containment vessels is bigger than that of the monobloc thick-walled explosion containment vessel in the center section of blasting under the same TNT. Numerical results are approximately in agreement with experimental ones. It is proved that the ribbon vessels have the valuable properties of " leak before burst at worst" compared with the monobloc vessels through numerical simulation.     

Rate-sensitive numerical analysis of dynamic responses of arched blast doors subjected to blast loading

Current practice in analysis and design of blast doors subjected to blast loading considers only simple boundary conditions and material properties. The boundary conditions and material properties, in fact, have considerable influence on the response of blast doors subjected to blast loading. In this paper, the dynamic responses of a reinforced concrete arched blast door under blast loading were analyzed by the finite element program ABAQUS, combined with a previously developed elasto-viscoplastic rate-sensitive material model. And the effect of the surrounding rock mass and contact effect of the doorframe were also taken into account in the simulation. It is demonstrated that the strain-rate effect has considerable influence on the response of reinforced concrete blast door subjected to blast loading and must be taken into account in the analysis.     

全容式 LNG 储罐桩基施工质量控制研究

全容式LNG低温储罐上部荷载较大,对差异沉降较敏感,基础施工要求非常严格。以天津全容式LNG储罐钻孔灌注桩施工为例,分析了影响桩基施工质量的因素,并提出了在施工过程中控制质量的措施及常见问题预防对策,以保障桩基施工质量。     

跨国公司高新技术专利遏制战略的渊源和特征——基于我国电子百强专利态势的分析

跨国公司的高新技术专利遏制战略是隶属于其宗主国的国家经济战略的子战略。专利遏制战略已成为国家安全战略的核心内容之一。专利遏制战略源于二战后西方国家的两种安全战略。并受国家经济战略特征的影响。在高新技术领域,跨国公司对我国企业不断强化专利遏制战略。我国企业崛起于世界舞台的过程,就是一步一步打破外国专利遏制战略。跻身世界一流企业之列的过程。     

Containment Rhetoric and the Redefinition of Third-Parties in the Equal Time Debates of 1959

This article suggests that the shortcomings of third-party presidential campaigns stem partially from a culture of rhetorical containment tracing back to a redefinition of third-parties during the 1959 congressional hearings over the equal time provision. After proposing a four-part framework for rhetorical containment, the article examines the case study of oddball perennial presidential candidate Lar Daly and his clash with the Federal Communications Commission, and an effort by the two major parties and media elite to exploit fears of his influence to portray third-parties as an invading horde of crackpots posing violence to democracy in the United States.     

先秦酒器简述

我国的酒器种类繁多,仅以先秦酒器为例,所出土就有20余种。酒器是酒文化的重要载体,通过研究酒器的造型和功能,可以直观地学习先秦的饮酒礼仪。文章参照《殷商青铜器通论》等书,结合先秦典籍中的文献记载,对先秦酒器做了简要的介绍。     

Dynamic Analysis of Structural Columns Subjected to Impulsive Loading

For a building structure subjected to impulsive loading, particularly shock and impact loading, the response of the critical columns is crucial to the behaviour of the entire system during and after the blast loading phase. Therefore, an appropriate evaluation of the column response and damage under short-duration impulsive loading is important in a comprehensive assessment of the performance of a building system. This paper reports a dynamic analysis approach for the response of RC columns subjected to impulsive loading. Considering that the dynamic response of a column in a frame structure can also be affected by the floor movement which relates to the global vibration of the frame system, a generic column-mass model is used, in which a concentrated mass is attached to the column top to simulate the effect of a global vibration. To take into account the high shear effect under impulsive load, the model is formulated using Timoshenko beam theory, and three main nonlinear mechanisms are considered. Two typical scenarios, one under a direct air blast loading, and another under a blast-induced ground excitation, are analyzed and the primary response features are highlighted.     

Dynamic Analysis of Structural Columns Subjected to Impulsive Loading

For a building structure subjected to impulsive loading, particularly shock and impact loading , the response of the critical columns is crucial to the behaviour of the entire system during and after the blast loading phase. Therefore, an appropriate evaluation of the column response and damage under short-duration impulsive loading is important in a comprehensive assessment of the performance of a building system. This paper reports a dynamic analysis approach for the response of RC columns subjected to impulsive loading. Considering that the dynamic response of a column in a frame structure can also be affected by the floor movement which relates to the global vibration of the frame system, a generic column-mass model is used, in which a concentrated mass is attached to the column top to simulate the effect of a global vibration. To take into account the high shear effect under impulsive load, the model is formulated using Timoshenko beam theory, and three main nonlinear mechanisms are considered. Two typical scenarios, one under a direct air blast loading, and another under a blast-induced ground excitation, are analyzed and the primary response features are highlighted.     

压力容器压力试验时免作强度校核的条件

压力容器在进行压力试验时，须先对在试验压力作用下的强度进行理论校核，合格后才能进行实际操作。通过综合分析和实例验证得出：在液压试验时，对碳素钢和低合金钢容器当PL≤0．19p、对高合金钢容器当PL≤0．1p时，则不必校核压力试验时的强度，可直接进行液压试验的实际操作；对作气压试验的容器，无论何种情况都不必校核压力试验时的强度，可直接进行气压试验的实际操作。     

应变率对混凝土动态强度性能影响的研究进展

综述应变率对混凝土动态强度性能的影响的试验研究进展情况,对目前国内外已开展的主要的混凝土动态特性实验研究成果进行分类说明与评述。包括单轴抗压动态加载、定侧压动态加载、双轴等比例动态加载、有初始静载的动态加载、单轴拉伸动态加载、有侧压的劈拉试验、循环荷栽作用下的拉伸试验以及考虑温度和湿度影响的动态加载试验。指出目前试验研究工作存在的问题,展望未来的发展趋势。对混凝土动态特性的研究今后仍将是本学科领域的一个热点。     

论区域经济增长的动力模型

经济增长理论研究方法的缺陷，使之在解释区域经济增长动力方面缺乏说服力。为解决区域经济系统的动力问题，作者提出了一个区域经济增长的动力模型，认为经济增长的推动力来源于制度，投资技术，企业家等四方面，在不同的发展阶段，各个推动力的作用是不同的，而且只有当其形成合力时，才能以最低成本获得经济增长。随后，作者应用该模型分析了目前中国经济增长的推动力问题，并指出落后的传统文化阻碍了西部的发展，而资金和技术是解决目前西部发展的关键；相对而言，东部地区提高推动力的关键是加强管理和创新。     

论协调发展的哲学意蕴

发展是人类永恒的主题，是解决一切问题的关键。在人类进入新世纪初，站在新的历史起点上，十六届三中全会上提出的科学发展观为我们指明了前进的方向。协调发展是科学发展观的核心部分，充分理解协调发展的理论内涵和哲学基础，是我们处理各种社会关系的行动指南和方法论。     

Analysis on Dynamic Response of Hard-Soft-Hard Sandwich Panel Under Blast Loading

Surface contact explosion experiments have been performed for the study of dynamic response of the hard-soft-hard sandwich panel under blast loading. Experimental results have shown that there are four damage modes, including explosion cratering, scabbing of the backside, radial cracking induced failure and circumferential cracking induced failure. It also illustrates that the foam material sandwiched in the multi-layered media has an important effect on damage patterns. The phenomena encountered have been analyzed by the calculation with ALE method. Meanwhile, the optimal analysis of foam material thickness and position in the sandwich panel were performed in terms of experimental and numerical analysis. The proper thickness proportion of the soft layer is about 20% to the thickness of sandwich panel and the thickness of the upper hard layer and lower hard layer is in the ratio of 7 to 3 under the condition in this paper when the total thickness of soft layer remains constant.     

Analysis on Dynamic Response of Hard-Soft-Hard Sandwich Panel Under Blast Loading

Surface contact explosion experiments have been performed for the study of dynamic response of the hard-soft-hard sandwich panel under blast loading. Experimental results have shown that there are four damage modes, including explosion cratering, scabbing of the backside, radial cracking induced failure and circumferential cracking induced failure. It also illustrates that the foam material sandwiched in the multi-layered media has an important effect on damage patterns. The phenomena encountered have been analyzed by the calculation with ALE method. Meanwhile, the optimal analysis of foam material thickness and position in the sandwich panel were performed in terms of experimental and numerical analysis. The proper thickness proportion of the soft layer is about 2.0% to the thickness of sandwich panel and the thickness of the upper hard layer and lower hard layer is in the ratio of ？ to 3 under the condition in this paper when the total thickness of soft layer remains constant.     

我国部分省份经济增长的转移动态特征

利用包含结构变化的样本自相关函数方法,采取1953—2007年我国21个省份的人均实际GDP数据,从一个新的视角对我国区域经济增长的转移动态特征进行实证分析,其结果表明,我国部分区域经济增长衰减速率表现为非线性振荡特征;除青海省外,样本中的其他省份的转移动态路径并不符合新古典索洛模型以指数收敛的转移动态特征,新古典增长指数收敛模型在刻画我国区域经济增长路径的能力上具有一定的局限性。     

Modeling Growth in Electronic Learning Environments Using a Longitudinal Random Item Response Model

In educational environments, monitoring persons' progress over time may help teachers to evaluate the effectiveness of their teaching procedures. Electronic learning environments are increasingly being used as part of formal education and resulting datasets can be used to understand and to improve the environment. This study presents longitudinal models based on the item response theory (IRT) for measuring persons' ability within and between study sessions in data from web-based learning environments. Two empirical examples are used to illustrate the presented models. Results show that by incorporating time spent within- and between-study sessions into an IRT model; one is able to track changes in ability of a population of persons or for groups of persons at any time of the learning process.     

Numerical Simulation of Dynamic Response of an Existing Subway Station Subjected to Internal Blast Loading

In order to design and retrofit a subway station to resist an internal blast,the distribution of blast loading and its effects on structures should be investigated firstly.In this paper,the behavior of a typical subway station subjected to different internal blast Ioadings was analyzed.It briefly introduced the geometric characteristics and material constitutive model of an existing two-layer and three-span frame subway station.Then three cases of different explosive charges were considered to analyze the dynamic responses of the structure.Finally,the maximum principal stress,displacement and velocity of the columns in the three cases were obtained and discussed.It concluded that the responses of the columns are sensitive to the charge of explosive and the distance from the detonation.It's also found that the stairs between the two layers have significant effects on the distribution of the maximum principal stress of the columns in the upper layer.The explicit dynamic nonlinear finite element software-ANSYS/LS-DYNA was used in this study.     

Numerical Simulation of Dynamic Response of an Existing Subway Station Subjected to Internal Blast Loading

In order to design and retrofit a subway station to resist an internal blast, the distribution of blast loading and its effects on structures should be investigated firstly. In this paper, the behav-ior of a typical subway station subjected to different internal blast loadings was analyzed. It briefly introduced the geometric characteristics and material constitutive model of an existing two-layer and three-span frame subway station. Then three cases of different explosive charges were consid-ered to analyze the dynamic responses of the structure. Finally, the maximum principal stress, dis-placement and velocity of the columns in the three cases were obtained and discussed. It con-cluded that the responses of the columns are sensitive to the charge of explosive and the distance from the detonation. It’s also found that the stairs between the two layers have significant effects on the distribution of the maximum principal stress of the columns in the upper layer. The explicit dynamic nonlinear finite element software——ANSYS/LS-DYNA was used in this study.     

经历循环荷载历史后饱和混凝土动态性能试验研究

为了研究循环荷载历史对饱和混凝土的力学性能的影响,采用φ150×300mm的圆柱体试件,对饱和混凝土试件在不同荷载循环次数(0次、25次、50次、100次)与不同应变速率(10-5/s、10-4/s、10-3/s、10-2/s)作用下进行单轴压缩试验,分析了荷载循环次数以及应变速率对饱和混凝土的峰值应力、峰值应变和弹性模量的影响。研究表明:经历循环荷载历史后的饱和混凝土峰值应力随应变速率的增大而增大,随荷载循环次数的增加表现出先增大后减小的规律;随荷载循环次数的增加,饱和混凝土的峰值应变先增大后减小,随应变速率的增大总体呈增大的趋势;随应变速率的增加,饱和混凝土的弹性模量整体上呈现出增大的趋势。     

Application of Latent Growth Curve Analysis With Categorical Responses in Social Behavioral Research

Latent growth modeling allows social behavioral researchers to investigate within-person change and between-person differences in within-person change. Typically, conventional latent growth curve models are applied to continuous variables, where the residuals are assumed to be normally distributed, whereas categorical variables (i.e., binary and ordinal variables), which do not hold to normal distribution assumptions, have rarely been used. This article describes the latent growth curve model with categorical variables, and illustrates applications using Mplus software that are applicable to social behavioral research. The illustrations use marital instability data from the Iowa Youth and Family Project. We close with recommendations for the specification and parameterization of growth models that use both logit and probit link functions.