双向IGBT开关在矩阵变换器中的应用

双向IGBT模块是实现高频矩阵变换器极为有效的方法。略不同于硬开关PWM变换器，矩阵变换器中的开关和传导损耗取决于所选的调制策略。本文介绍了一种由诺丁汉大学推导的平均损耗的计算公式。测试一个使用1200V，200A的双向模块实现的三相到单相的构造，得到的波形说明了矩阵变换器的实际操作以及可能会出现的输出电流纹波。     

Managing fire risk onboard offshore platforms: Lessons from Piper Alpha and probabilistic assessment of risk reduction measures

The offshore oil platform Piper Alpha was destroyed in July 1988 by a catastrophic fire. The causes of the accident included a combination of technical and organizational factors. In this paper, I describe the accident, its chronology, and the dependencies involved. I then examine some of the human errors that led to the disaster and their organizational roots, such as economic pressures, the permit-to-work system, and the inadequacy of regulatory oversight in the United Kingdom at the time of the accident. Risk-reduction measures can be costly, however, and priorities must be set based on costs and benefits. To this end, I describe a probabilistic risk analysis model that can be used to assess the benefits of different fire safety measures, focusing on reinforcing the emergency water pumps.     

Holiday weight management by successful weight losers and normal weight individuals.

This study compared weight control strategies during the winter holidays among successful weight losers (SWL) in the National Weight Control Registry and normal weight individuals (NW) with no history of obesity. SWL (n = 178) had lost a mean of 34.9 kg and had kept ≥13.6 kg off for a mean of 5.9 years. NW (n = 101) had a body mass index of 18.5-24.9 kg/m2. More SWL than NW reported plans to be extremely strict in maintaining their usual dietary routine (27.3% vs. 0%) and exercise routine (59.1% vs. 14.3%) over the holidays. Main effects for group indicated that SWL maintained greater exercise, greater attention to weight and eating, greater stimulus control, and greater dietary restraint, both before and during the holidays. A Group × Time interaction indicated that, over the holidays, attention to weight and eating declined significantly more in SW than in NW. More SWL (38.9%) than NW (16.7%) gained ≥1 kg over the holidays, and this effect persisted 1 month later (28.3% and 10.7%, respectively). SWL worked harder than NW did to manage their weight, but they appeared more vulnerable to weight gain during the holidays. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A C finite element method for the analysis of inextensible pipe lines

A C⁰ finite element method in which rotations and displacements are coupled by a penalty function formulation is developed for pipe line analysis. Inextensibility is also handled by a penalty method. Simplicity and effectiveness of this approach is illustrated by three dimensional computations including contact problems and an appendix giving all necessary stiffness matrices.