Earth return path impedances of underground cable for three-layer earth

One of the factors that affect the parameters of an underground cable is earth return path impedance. Pollaczek developed a formula for the case of one-layer （homogenous） earth. But in practice the earth is composed of several layers. In this study we develop a new formula for earth return path impedance in the case of a three-layer earth. To check the accuracy of the obtained results, a comparison has been made with the finite element method （FEM）. A comparison between the results of the Pollaczek formula and results of the obtained formula for a three-layer earth has been made, showing that the use of the Pollaczek formula instead of the actual formula can cause serious errors.     

What helps children in a pupil referral unit (PRU)? An exploration into the potential protective factors of a PRU as identified by children and staff

Previous studies have focused on the views of excluded children or those finding themselves in Pupil Referral Units (PRUs). Few, however, have focused on exploring views from a resilience perspective. Studies linked to resilience have tended to focus on exploring factors through quantitative rather than qualitative measures. This piece of research aimed to explore the potential protective factors of one PRU through the valuable voices of children and staff. The views of six children aged between 9 and 13 years, all with varying forms of behavioural, emotional and social difficulties, and partway through a PRU placement, were explored through semi-structured interviews supported by the use of tools and techniques to facilitate discussion. The views of four staff members were also obtained. Findings reveal the powerful perspectives that children and young people can bring in relation to what might be helping them within a particular environment. A number of potential protective factors, both within the environment and within-child factors that may operate as mechanisms in fostering positive social and academic outcomes, are identified. Implications of these findings for professional practice, and for children finding themselves in PRU provision, are discussed, with a focus on reintegration and the potential impact of changing environments for these children.     

浅析TAIC、BIPB在橡胶电缆中的应用

文章介绍橡套电缆绝缘胶和护套胶使用三烯丙基异三聚氰酸酯(TAIC)和双叔丁基过氧化二异丙基苯(BIPB)作硫化体系的原因,以及在橡套电缆中的具体应用实例,并阐述在使用过程中应注意的事项。     

智能化大厦的综合布线系统综述

综合布线系统是智能化大厦的信息基础设施，它将取代传统的建筑布线结构。笔者对综合布线系统的实施目标、采用的整体化开放配线系统及系统所采用的材料和如何实施等诸方面进行了介绍。     

高职外贸专业英语函电课程教学初探

在高职外贸专业教学中,英语函电是最重要的课程之一。该门课程的目的是培养学生外贸专业能力,提高学生的综合素质。交际教学法和理论与实践相结合教学法是适合本门课程的教学方法。     

预应力正放四角锥网架布索方案比较

本根据有限元理论编制的静力分析程序对正放四角锥网架的布索方案进行分析，得出较优布索方案。     

三维前方交会在网架屋面质量监测中的应用

重点探讨了三维前方交会法的原理及其在金属网架结构屋面施工的质量监测方法,保证施工质量,达到设计要求,为今后的安全运营提供了可靠的依据。同时为大型无支撑建筑屋面的变形监测提供了一种测量监测依据。     

从当代文学看文艺的生态价值建构

自然是人类的母亲，可是随着科技的发展，人们为了满足一己之私往往无视自然的存在，肆意地对大自然进行掠夺，造成我们生态之居的恶化，人们普遍要求一种生态的关怀，这在当代文学上已十分明显地反映出来。本文欲对当代文学的这一现象进行归结和分析以期对生态文艺的建设尽自己的一份力量。     

社会分层对进城农民工留城意愿的影响初探

本文首先概括了国内对进城农民工留城影响因素的研究成果,并指出由于角度的单一化所造成的理解上的片面。影响农民工留城的因素除了个体在微观层面上的考虑,还有一种更广层面上的原因即社会分层的影响。本文主要从农村和城市社会的分层两方面入手,考察这两部分的分层所造成的后果中对农民工留城会产生影响的元素。     

“快易网球”在高校教学的应用和实施

“快易网球”给高校网球教学带来了全新的理念和教学方法,相对比传统网球教学方法,在高校进行“快易网球”的教学实践也证明了“快易网球”具有很强的可行性。但是在高校教学中也出现了很多共性问题,该文通过文献查阅、实地考察法进行探究发现,解决突出共性问题将使学生在“快易网球”教学中的学习更加迅速、乐享和标准,并快速融入游戏和比赛,也期望对我国高校网球教学发展有一定的促进作用。