Dynamic responses of cable-stayed bridges to vehicular loading including the effects of the local vibration of cables

Stay cables, the primary load carrying components of cable-stayed bridges (CSBs), are characterised by high flexibility which increases with the span of the bridge. This makes stay cables vulnerable to local vibrations which may have significant effects on the dynamic responses of long-span CSBs. Hence, it is essential to account for these effects in the assessment of the dynamics CSBs. In this paper, the dynamic responses of CSBs under vehicular loads are studied using the finite element method (FEM), while the local vibration of stay cables is analyzed using the substructure method. A case study of a cable-stayed steel bridge with a center span of 448 m demonstrates that stay cables undergo large displacements in the primary mode of the whole bridge although, in general, a cable’s local vibrations are not obvious. The road surface roughness has significant effects on the interaction force between the deck and vehicle but little effect on the global response of the bridge. Load impact factors of the main girder and tower are small, and the impact factors of the tension of cables are larger than those of the displacements of girders and towers.     

高职教育实践教学体系要素构建研究

文章探讨了高职教育实践教学体系的特征,构建高职实践教学体系的原则,阐述了高职实践教学体系的构成要素,构建实践教学体系应注意的几个环节。     

Exploring the cosmopolitanism in China: examining mosheng ren (“the stranger”) communication through Momo

This paper discusses a phenomenon that has become popular in mainland China in recent years, “mosheng ren communication,” focusing specifically on an application known as Momo, a social discovery and dating platform that is widely used in China. It first outlines the context of post-Mao China, which has produced urbanism, individualization, and a sexual revolution. Thereafter, it turns to the theories of the stranger and cosmopolitanism, which are used to analyze mosheng ren communication. This paper adopts cultural discourse analysis as the analytical procedure to present the findings of online and offline interviews conducted in both Beijing and Shanghai to examine how Momo users in urban metropolises make use of this app in order to analyze the cultural radiants in their communication practices. Based on the data obtained, this paper analyzes mosheng ren communication in the Chinese context and describes how Momo is designed to facilitate it. Momo users can enter into sexual relations based on the use of authentic photos on their profiles; alternatively, they can communicate anonymously. They are also “in-between” traditional Chinese values and new values. Momo users contribute a Chinese form of cosmopolitanism through cultivation of insensitivity to mosheng ren, while their engagement in mosheng ren communication implies that the members of are more open to others.     

土荆芥浸提液对几种种子萌发的化感作用

采用室内生物测定法,以小麦,油菜,上海青等作物为受体,研究了土荆芥的化感作用.结果表明:①土荆芥叶的浸提液对3种作物种子萌发均具有抑制作用,且这种抑制作用随着浸提液浓度的增加而增强;②浓度为0.01g/mL和0.02g/mL的茎的浸提液对上海青、油菜的幼苗生长有促进作用;③相同浓度的土荆芥叶浸提液对供试种子萌发的的抑制作用强于茎浸提液.     

三维电子水平测试仪制作说明

应城一中秉承"以人为本,为学生的终身发展奠基"的办学理念,为了使学生了解社会,学校有目的、有计划组织我们参加社会实践活动。在09年暑期社会实践活动中,我们发现建筑工人、装修工人、泥瓦匠师傅们测量建筑平面是否水平使用的是水平尺。水平尺是通过看气泡是否"居中"来判断是否水平。由于工作环境中泥沙、灰尘多,师傅们要用带泥水的手拿来拿去,水平尺常常弄得很模糊,看起来很吃力,有时甚至看得流泪,还是比较难以分辨;特别是光线不好的时候,更是难以看准,只能凭经验和感觉;而且,     

新入职教师课堂教学方法的选择与运用

对即将从事教育工作的新入职教师而言,在学校课堂教学中不仅要考虑指导学生获得直接的知识经验,更要考虑教导他们以最简单、最便捷的途径和方法,有效地获取更多的间接知识经验,这就有一个如何选择与运用课堂教学方法的问题。为此,在选择教学方法时首先要遵循目标性原则、效率性原则和以学定教原则,还要关注到应用每种方法的制约条件,这样才能有效地提高教学质量。     

中国特色社会主义教育发展道路的基本经验

改革开放以来,在党和政府的领导下,我国走出了一条中国特色社会主义教育发展道路。总结中国特色社会主义教育发展道路的基本经验,不仅可以为未来我国教育改革和发展提供指导,还可以为世界其他国家特别是发展中国家的教育改革与发展提供启示。实践证明,坚持教育的优先发展战略地位,坚持以改革和创新为发展动力,坚持把教育公平作为基本的教育政策,坚持把提高质量作为教育的生命线,坚持以加强教师队伍建设为关键,坚持以加大教育经费投入为保障,坚持教育国际化与本土化的统一,坚持以重点建设带动教育的整体发展,坚持统筹规划、分步实施、试点先行、动态调整,坚持依法治教等是党和政府开辟中国特色社会主义教育发展道路的基本经验。     

Calculation method for effect of silt sediment on lifting force of hydraulic gate

In this paper, silt sediment is considered to be Bingham body, which is made up of coarse and fine particles in front of a hydraulic gate. The coarse and fine particles provide friction and shear stress in the course of opening the gate. They constitute together the adhesion force of the sediment. Based on this viewpoint, this paper puts forward a formula for the effect of silt sediment on the lifting force. The formula includes gate weight, down-suction force, sealing rubber friction, plus-weight, water-column pressure, plus-silted-sediment weight and rolling (or sliding)-bearing friction. Finally, the verification results show that the formula has certain reliability and the calculation accuracy can meet the need of practical engineering.     

Low-power three-stage amplifier using active-feedback Miller capacitor and serial RC frequency compensation

A low-power three-stage amplifier for driving large capacitive load is proposed. The feedback path formed by the active-feedback Miller capacitor leads to a high frequency complex-pole but a high Q-value, which significantly deteriorates the stability of the amplifier. The serial RC stage introduced as the second stage output load can optimize the resistor Rz and the capacitor Cz under fixed power and small compensation capacitor Ca, which brings about a suitable Q-value of the complex-pole and the gain-bandwidth product extension of the amplifier. The amplifiers were designed and implemented in a standard 65 nm CMOS process with capacitive loads of 500 p F and 2 n F, respectively. The post-layout simulation results show that the amplifier driving the 500 p F capacitive load can achieve a gain of 113 d B, a phase margin of 50.6° and a gain-bandwidth product of 5.22 MHz while consuming 24 μW from a 1.2 V supply. For the 2 n F capacitive load, the amplifier has a gain of 102 d B, a phase margin of 52.8°, a gain-bandwidth product of 4.41 MHz and a power of 43 μW. The total compensation capacitors are equal to 1.13 p F and 1.03 p F. The better figures-of-merits are 108 750 and 205 113(MHz×p F/m W). The layout areas are 0.064 mm×0.026 mm and 0.063 mm×0.027 mm. Compared with the CFCC scheme, the gainbandwidth product is extended by 1.6 times at CL=500 p F and Ca=1.1 p F.     

公民社会视角下大学生政治参与的特点与引导

公民社会为学生政治参与提供广阔的平台,大学生政治参与为公民社会提供重要的人才支持。当前,公民社会呼唤大学生政治意识、公民意识的形成和完善。在公民社会的背景下,学生政治参与途径与方式日益多样化,对其特点进行归纳分析并寻求相关引导性对策具有现实必要性。