Design and Experimental Verification of a Linear Permanent Magnet Generator for a Free-Piston Energy Converter

This paper discusses issues that are pertinent to the design of a linear permanent magnet generator for application in a free-piston energy converter. To achieve the required high power density, high efficiency, and low moving mass, a tubular machine equipped with a modular stator winding and a quasi-Halbach magnetized armature is employed. It is shown that the machine design can be optimized with respect to three key dimensional ratios while satisfying other performance requirements. It is also shown that, when the generator is interfaced to an electrical system via a power electronic converter, both the converter volt-amps rating and the converter loss should be taken into account when optimizing the machine design. The performance of such a tubular generator is demonstrated by measurements on a 10-pole/9-slot prototype machine.     

如何为黑白照片上色

<正>想要让老旧的黑白照片重新焕发光彩吗?Ben Brain将教大家一套比较简单的方法为扫描的黑白旧照片手工上色。如果你手上有一些黑白的旧照片或者单色的数码文件需要为其上色,那么这篇教程正适合你。我们将会告诉你如何在数码     

拍出《Top Gear》风格的汽车大片

想拍出全球最畅销的汽车杂志《Top Gear》风格的精彩大片么?想要留下汽车的艺术性微距影像吗? Ed Godden向你展示如何拍出更好的汽车摄影作品。     

The regional structure of the united states economy

A methodology is developed to divide an economy into regions, then is applied to the United States. These regions represent a departure from the ones currently used by the Bureau of Economic Analysis and the Bureau of the Census, both of which are criticized for being derived in anad hoc fashion. The methodology uses a multiregional input-output model, which is viewed as the simplest type of general equilibrium model containing regional detail. The optimal regions developed using this methodology are ones that minimize aggregation error.An earlier version of this paper was presented at the 35th North American Meetings, Toronto, November 1988.     

What is false memory development the development of? Comment on Brainerd, Reyna, and Ceci (2008).

In this commentary, assumptions about the nature and development of children's false memories as described in a recent article by C. J. Brainerd, V. F. Reyna, and S. J. Ceci (2008; see record 2008-04614-001) are reviewed. Specifically, questions are raised about what drives the development of false memories in fuzzy-trace theory (FTT). Recent studies that challenge a core assumption of FTT, that false memory illusions increase across development as children learn to establish meaningful connections across items (i.e., establish gist), are discussed. An alternative conceptualization of the development of false memory illusions, associative-activation theory (AAT), is presented. AAT provides as viable an account of the development of false memory illusions as does FTT and anticipates a unique set of outcomes that have recently appeared in the developmental literature on false memory illusions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Empathy in preschool children: The development of the Southampton Test of Empathy for Preschoolers (STEP).

In this study, we investigated a new instrument: the Southampton Test of Empathy for Preschoolers (STEP). The test incorporated 8 video vignettes of children in emotional scenarios, assessing a child's ability to understand (STEP-UND) and share (STEP-SHA) in the emotional experience of a story protagonist. Each vignette included 4 emotions (angry, happy, fearful, sad) that reflected emotion judgments based on the protagonist's facial expression, situation, verbal cues, and desire. The STEP was administered to 39 preschool children, and internal reliability, concurrent validity, and construct validity were addressed. The results showed good internal consistency. They also highlighted moderate concurrent validity with parent-rated empathy, a measure of facial indices, and construct validity with teacher-rated prosocial behavior. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Analysis of a short-stroke, single-phase, quasi-Halbach magnetised tubular permanent magnet motor for linear compressor applications

The analysis of a novel single-phase, short-stroke, reciprocating tubular motor with a quasi-Halbach magnetised moving-magnet armature is described. The motor was developed for applications such as linear compressors. The magnetic field distribution, the back-emf and the thrust force of the motor are established analytically in the cylindrical co-ordinate system, and predictions are compared with results derived from finite-element (FE) analysis. It is shown that the difference between the analytical and FE predicted average emf (thrust force) over the operating stroke of 0.01 m is <5%. The analysis and the emf and thrust force predictions are validated by measurements.