Comparison of various procedures for progressive collapse analysis of cable-stayed bridges

Alternate path(AP) method is the most widely used method for the progressive collapse analysis,and its application in frame structures has been well proved.However,the application of AP method for other structures,especially for cable-stayed structures,should be further developed.The four analytical procedures,i.e.,linear static,nonlinear static,linear dynamic,and nonlinear dynamic were firstly improved by taking into account the initial state.Then a cable-stayed structure was studied using the four improved methods.Furthermore,the losses of both one cable and two cables were discussed.The results show that for static and dynamic analyses of the cable-stayed bridges,there is large difference between the results obtained from simulations starting with either a deformed or a nondeformed configuration at the time of cable loss.The static results are conservative in the vicinity of the ruptured cable,but the dynamic effect of the cable loss in the area farther away from the loss-cable cannot be considered.Moreover,the dynamic amplification factor of 2.0 is found to be a good estimate for static analysis procedures,since linear static and linear dynamic procedures yield approximately the same maximum vertical deflection.The results of the comprehensive evaluation of the cable failure show that the tread of the progressive failure of the cable-stayed bridges decreases when the location of the failed cables is closer to the pylon.     

Identification of sources of pollution and contamination in water distribution networks based on pattern recognition

An intrusion of contaminants into the water distribution network (WDN) can occur through storage tanks (via animals, dust-carrying bacteria, and infiltration) and pipes. A sensor network could yield useful observations that help identify the location of the source, the strength, the time of occurrence, and the duration of contamination. This paper proposes a methodology for identifying the contamination sources in a water distribution system, which identifies the key characteristics of contamination, such as location, starting time, and injection rates at different time intervals. Based on simplified hypotheses and associated with a high computational efficiency, the methodology is designed to be a simple and easy-to-use tool for water companies to ensure rapid identification of the contamination sources, The proposed methodology identifies the characteristics of pollution sources by matching the dynamic patterns of the simulated and measured concentrations. The application of this methodology to a literature network and a real WDN are illustrated with the aid of an example. The results showed that if contaminants are transported from the sources to the sensors at intervals, then this method can identify the most possible ones from candidate pollution sources. However, if the contamination data is minimal, a greater number of redundant contamination source nodes will be present. Consequently, more data from different sensors obtained through network monitoring are required to effectively use this method for locating multi-sources of contamination in the WDN.     

大学英语测试中多项选择词汇题和阅读选词填空信度、效度比较

大学英语词汇测试主要有两种题型:多项选择题和阅读选词填空。目前,随着词汇测试语境化的发展趋势,在句子中考词汇的多项选择题型正逐渐被在语篇中考词汇的阅读选词填空替代。本文将重点比较两种题型的信度、效度,探讨如何设计更有效的词汇测试题目。     

地方债务风险问题研究

地方政府债务融资是一把"双刃剑",在经济运行良好的时候可以促进当地经济的发展,但是过高的债务则可能拖垮当地的经济[1]。随着我国市场化与城市化的程度日益加深,建设资金缺口越来越大,但是目前的融资体系不规范,使我国地方政府债务风险高企。如何完善融资体系,降低地方债务风险已经成为当前一大课题。本文在研究地方债务内涵的基础上,分析了地方债务风险产生的原因,探讨了过高的债务可能产生的后果,并提出了相关建议。     

当代大学生诚信缺失分析与对策探析

诚信是社会发展的基本行为规范,是为人处事基本行为道德标准,也是社会文明程度的体现。本文首先揭示了大学生诚信缺失的主要表现,分析了大学生诚信缺失的原因,提出了建立思想政治与诚信道德相结合的教育机制,建立大学生诚信奖惩机制,建立个人诚信档案制度的方法和策略来解决大学生诚信缺失。     

哈利波特系列小说与希腊神话的渊源

《哈利·波特》系列作品畅销的秘诀有很多,其中之一便是,小说魔法世界的创作原型包含的诸多西方文化元素。本文拟从欧洲文明的两大根源之一的希腊神话这个角度来解读这套十年不衰的经典儿童文学作品。     

浅谈高校旅游英语的教学改革

随着我国经济的发展,旅游行业在发展的过程中,不仅要面对国内市场,同时还要面对国外市场。因而在交流的过程中,急需一批旅游英语的人才。而高校作为人才培养的重要基地,不仅肩负着人才培养的重任,同时还关系着我国社会主义的建设。在高校旅游英语教学中,以往的教学模式已无法适应新时期的教学需求,在此,本文针对高校旅游英语的教学改革,做以下论述。     

教育理论与教育实践关联之基点

教育理论与教育实践关联的基点在于真实的教育问题,这是重构理论与实践互动关系的新视角。教育理论源自教育实践中的问题,教育问题意识的弱化是我国教育理论贫困的深层原因,教育理论的贫困加深了理论与实践之间的鸿沟。教育理论与教育实践联系的重构需要教育研究共同体进入教育场景发现和思考本土教育问题。     

专利产出与广东经济增长关系研究

此文选取1985-2010年的时间序列数据,运用协整检验和Granger检验,对广东专利申请量产出和经济增长之间的关系进行了实证研究。结果表明：专利产出和GDP之间存在长期协整关系,协整系数为0．2-817;二者在10％水平上具有Granger双向因果关系,但在5％的水平时,经济增长对专利产出的影响强度相对较弱,专利产出对经济增长的影响强度相对较强,这主要是因为广东的研发投入还不足,广东快速增长的经济没有带来专利产出数量的增长。我国还需进一步深化科技体制改革,不断完善科技经费的投入机制,要加大财政支持力度,加强科研基础设施的建设,一副造良好的科研环境。     

对泛在学习资源建设的几点思考

无线通信技术、计算机网络技术、移动计算技术的高速发展,推动了泛在学习的发展。这是一种"人人、时时、处处"的学习方式,是泛在计算技术支持下的一种新的学习方式,而这种学习方式需要庞大的学习资源。在泛在学习概念的基础上,分别从6个方面提出对泛在学习资源建设的几点思考,希望这些思考能对实际的资源建设起到积极的作用。