EMC中的接地技术及地线中的干扰

讨论了接地的几种方式，探讨了地线中带来的电磁干扰，介绍了抑制和消除电磁干扰的途径和方法．     

电磁兼容技术在自动化专业实验室中的应用

电磁兼容作为一门边缘学科,其应用越来越广泛;分析了自动化专业实验室中主要电磁干扰,并结合电磁干扰产生原因的具体情况,探讨了采取相应抑制措施。     

电磁干扰在数字电路板设计中的研究

主要从电磁兼容设计的目的、电磁干扰的途径以及电磁干扰抑制等方面进行阐述，为实际电路板设计提供参考．     

关于开关电源电磁干扰分析与抑制问题的探讨

开关电源由于本身工作特性使得其电磁干扰问题相当突出.以高频开关电源为例,介绍了开关电源的工作原理,分析了开关电源产生电磁干扰的原因,提出了多种抑制电磁干扰的措施.在开关电源的设计中,只有全面分析开关电源电磁干扰产生的原因,并根据实际情况采取有效的措施来抑制电磁干扰,改善其电磁兼容性.     

浅析信号检测和控制系统中的接地设计

接地是抑制电磁干扰、提高信号检测控制系统性能的重要手段之一,接地问题处理的好坏直接影响电路的正常工作。正确的接地既能提高系统抗干扰的能力,又能减少其对外的电磁干扰的发射。     

减小自制超声检测仪器电磁干扰研究

为了尽量降低电磁干扰引起的测量误差,在分析了不同性质电磁干扰的基础上,以超声混凝土内裂纹检测实验为例,论述了立足实验室条件降低电磁干扰的一般方法。实验结果表明,综合采用这些方法能够有效降低电磁干扰,增强实验结果的可重复性。     

光伏逆变器内部电磁干扰抑制电路研究

在光伏逆变系统中,内部电磁干扰是影响其工作稳定性和可靠性的重要因素,能否有效地控制内部电磁干扰决定着系统的成败.文章以一款3 kW离网光伏逆变器设计为例,分析了系统内部主要电磁干扰的分布,并提出了具体解决方案.     

数字系统中的电磁兼容探讨

分析了对数字系统性能影响严重的噪声源--串扰噪声、反射、接地公共阻抗噪声等,提出了抑 制电磁干扰的有效措施.     

电磁干扰抑制技术

介绍了电磁干扰(EMI)的基本概念,围绕电磁干扰三要素,介绍了各种不同的电磁干扰抑制技术以及电磁兼容设计思路,强调了电子产品在设计初即进行EMC研究的重要性。     

综合布线系统与电磁干扰

从综合布线系统与电磁干扰的关系入手,分析了电磁干扰的危害,提出在综合布线系统中防电磁干扰的措施：布线设计时要严格把关,统一规划,并在特定的地点增加屏蔽系统．     

Have the shifting sands of Fordism resulted in ground lost or ground gained for distance education?

Industrialisation and distance education make uncomfortable bed fellows. This article critically analyses the paths travelled by distance education when burdened by industrial sociology. The models for industrialisation, specifically Fordist and post‐Fordist ones, whether methodologically anchored in modernity or post‐modernity, are argued as having relevance only to the production aspects of distance education. The attempts of various authors in distance education over recent years to identify strong paradigmatic links between distance education and industrialisation have resulted in the qualities of distance education as an educational process being overlooked or rejected in favour of a supposedly more ‘open’ form of teaching and learning.     

如何让企业培训落地开花

在越来越多企业倡导"人性化,学习型"组织为企业口号的今天,企业培训成为很多企业的首要选择,也是落实这个口号最直接、最有效的方法。但是怎样才能做好培训,培训哪些内容才能真正让培训为企业服务,这是个值得思考的问题。     

Wind characteristics near the ground during typhoon Meari

Wind speed and direction data during typhoon Meari were obtained from eight anemometers installed at heights of 10, 20, 30, and 40 m on a 40-m tower built in the Pudong area of Shanghai. Wind-turbulence characteristics, including wind-speed profile, turbulence integral scale, power spectra, correlations, and coherences were analyzed. Wind-speed profiles varied with time during the passage of Meari. Measured wind-speed profiles could be expressed well by both a power law and a log law. Turbulence integral scales for u, v, and w components all increased with wind speed. The ratios of the turbulence scales among the turbulence components averaged for all 10-min data were 1? 0.69?0.08 at 10 m, 1?0.61?0.09 at 20 m, and 1?0.65?0.13 at 40 m. The turbulence integral scales for the u and v components increased with average gust time, but the turbulence integral scale for the w component remained almost constant when the gust duration was greater than 10 min. The decay factor of the coherence function increased slightly with wind speed, with average values for longitudinal and lateral dimensions of 14.3 and 11.3, respectively. The slope rates of the turbulence spectra in the inertial range were less than ?5/3 at first, but gradually satisfied the Kolmogorov 5/3 law. The longitudinal wind-power fluctuation spectrum roughly fitted the von Karman spectrum, but slight deviations occurred in the high-frequency band for lateral and vertical wind-power fluctuation spectra.     

Toward solidarity as the ground for changing science education

In science education, reform frequently is conceived and implemented in a top-down fashion, whether teachers are required to engage in change by their principals or superintendents (through high-stakes testing and accountability measures) or by researchers, who inform teachers about alternatives they ought to implement. In this position paper on science education policy, I draw on first philosophy to argue for a different approach to reform, one that involves all stakeholders—teachers, interns, school and university supervisors, and, above all, students—who participate in efforts to understand and change their everyday praxis of teaching and learning. Once all stakeholders experience control over the shaping and changing of classroom learning (i.e., experience agency), they may recognize that they really are in it together, that is, they experience a sense of solidarity. Drawing on ethnographic vignettes, science teaching examples, and philosophical concepts, I outline how more democratic approaches to reform can be enabled.     

强夯法加固地基的应用实践

强夯法是近些年出现的突破原来压实原理的一种地基处理方法,以石家庄大学(石电大)学生宿舍楼地基处理工程为基础,通过对有关数据的分析,探讨了其在提高地基承载力、消除地基土湿陷性方面的应用.     

School Inspection: who hath measured the ground?

Concern about the quality of inspection voiced in the late 1980s was justifiable. However, the message to Government (for example, from the Audit Commission) was not to marginalise local education authorities (LEAs) and scrap local inspection but to involve itself to improve it. What Government did in setting up OFSTED was to establish a monopoly of one inspection approach under effectively a single inspectorate. This was undesirable, since it not only confuses the purposes of inspection, but also fails to produce the kind of information that parents and others involved with schools really need. The paper argues for a more flexible approach in which comprehensive OFSTED‐style inspections need only be used sparingly. The future role of OFSTED should be as a small regulating body assuring the quality of local inspections, whether carried out by LEA or independent teams