Design at the very core [Manufacturing Apple]

Anne Harris meets some of the industrial designers whose work has made Apple a style icon for more than three decades.     

Designing the next generation test system with PXI at the core

Overview The growing trends for convergence of functionality and divergence in standards are creating new opportunities for test engineers to develop next generation test systems that greatly contribute to accelerating the product development cycle as well as maintaining test system longevity because they are possible to upgrade to the rapid technological advancement.     

Computing the internal transient voltage response of a transformerwith a nonlinear core using Gear's method. II. Verification

An EHV transformer's insulation structure must be designed to withstand the internal electrical stresses generated during system transients. Computer models are employed for predetermination of these stresses. Part I of this paper developed a detailed transformer model and solution method representing the nonlinear, saturable characteristic of tire core during transients. The resulting set of stiff nonlinear differential algebraic equations are solved by application of Gear's method. Part II presents the verification of this methodology. This is accomplished by comparing the computed and measured response of a 765/345/34.5 kV 500 MVA autotransformer during energization and transient excitation     

Computing - Into the fastlane

This paper describes an application-specific processor (add-on chips) that helps computers work harder without consuming massive amounts of energy. If the problem is the power demand of general-purpose processors, the answer may lie in the application-specific acceleration, a technique being tried out in supercomputers. UK-based Clearspeed Technology reworked a chip design developed for PC graphics into a massively parallel floating-point calculation workhouse. Another main option for acceleration is to use a field-programmable gate array (FPGA), whose logic circuits are not hardwired but defined by loading a configuration memory     

服务计算新模式：雾计算

简单介绍了雾计算产生的时代背景、基本概念以及与其他相关概念之间的关系,描述了其组织结构和形式化描述方法。认为雾计算系统实体以开放、自主的方式存在于各个节点上,同时,也具有一定的独立性、多态性和自适应性。     

情感计算

情感计算是关于情感、情感产生以及影响情感方面的计算,其目的是赋予计算机识别、理解、表达和生成各种情感特征的能力,最终使计算机像人一样能进行自然、亲切和生动的交互。简要介绍了有关情感计算的发展、应用、研究等内容,通过分析和比较,对情感计算现状的认识进行了总结,并展望了今后的发展方向。     

Measurement of the inductance of a coil with core at different currents by a dc chopper

Contents This paper describes a new method for the measurements of the dynamic inductance of a coil with a saturable core. A formula for dynamic inductance is obtained by analyzing the proposed measurement circuit. In this method, a controllable dc voltage source, a dc chopper and a measurement system based on a PC, Lab-VIEW data acquisition card are used. The duty cycle of the dc copper is equal to the half pulse cycle and, the coil current at which the inductance is to be measured, is obtained by changing the input voltage V _d . The peak-to-peak ripple current in the formula is determined by the measuring system.

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übersicht Es wird ein neues Verfahren zur Messung der dynamischen Induktivit?t einer Spule mit s?ttigbarem Kern vorgestellt. Ausgehend von der Analyse des vorgeschlagenen Me?kreises wird eine Formel für die Induktivit?t hergeleitet. Das Verfahren benutzt eine steuerbare Gleichstromquelle, einen Gleichstromsteller und eine Me?einrichtung aus PC und Datenerfassungskarte. Als Einschaltzeit des Stellers wurde die halbe Pulsperiode gew?hlt. Die Einstellung des Stroms für die Me?punkte erfolgt durch ?nderung der Eingangsspannung. Die gemessene Stromschwankung geht in die Formel zur Bestimmung der Induktivit?t ein.

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Received: 25 November 1999     

基于云计算的电磁问题并行计算方法

针对电工装备性能分析与优化所需的易用高性能计算问题,使用云计算技术搭建了弹性集群,实现了典型电磁问题在弹性集群中的并行计算。使用虚拟化技术将计算机资源整合为资源池,搭建并部署了可实现弹性计算的云平台及并行计算所需的弹性集群。计算节点通过千兆路由器相连,节点之间使用SSH通信协议。选取感应电机和变压器作为计算案例,使用Fortran编写静磁场计算程序。对云计算的并行架构Open Mpi与Map Reduce进行了分析研究,使用Open Mpi并行化方法实现了数百万计算节点的并行计算。并通过与商业软件计算结果的对比验证了计算的正确性。研究结果表明,可在云计算的弹性集群上使用Open Mpi实现大规模并行计算。相比超级计算机提供的并行计算方案,本文使用云计算建立的弹性机群具有便捷、按需、可配置的优点,这为高性能计算提供了一种更易获取、易用的解决方法,为开展复杂真实机构的集成计算提供了高性能计算的理论和实践依据。     

基于志愿计算的云平台的构建方法与架构研究

提出了基于志愿计算模式的云计算平台的构想,在对比分析了传统的志愿计算平台和云计算平台架构的基础上,阐述了志愿计算的云平台的理论模型和实现框架,并提出了今后的研究内容与方向。     

云计算:构建未来电力系统的核心计算平台

针对传统电力系统计算平台在计算、存储、信息集成和分析等方面的不足,提出建立基于云计算的电力系统计算平台。首先概述了云计算的基本概念和主要特征,并比较了云计算和另一种大规模分布式计算模式——网格计算的不同。从物理组成、系统架构、软件技术等方面详细讨论了电力系统云计算平台的实现。之后,展望了云计算在电力系统安全分析、潮流与优化潮流计算、系统恢复、监控、调度、可靠性分析等领域的应用前景。最后,讨论了电力系统云计算研究中有待解决的几个重要问题。     

Computing with neural networks

The resurgence of interest in neural networks is discussed. This interest is prompted by two facts. First, the nervous systems of simple animals can easily solve problems that are very difficult for conventional computers. Second, the ability to model biological nervous system functions using man-made machines increases understanding of that biological function. Two popular models of neural networks, the feedforward model and the feedback model, are described. Adaptation or learning, a major focus of neural network research, is detailed     

Computing forces on conductors in the presence of dielectricmaterials

This paper is intended to correct a mistaken assumption often made in the computation of the force on the plates of a simple dielectric filled capacitor. The mistake results in a false prediction of the force, which can be orders of magnitude in error. Students preparing for work in macro- or nanotechnology should be provided with a correct understanding of how electrostatic forces should be computed within dielectric materials, and how these forces affect bearing load. This particular example seems to be characteristically absent from undergraduate electromagnetic texts     

可靠计算及其在电力系统中的应用

针对电力系统计算中会遇到计算机数值计算误差和电力系统数据处理造成的不确定性问题,提出了将可靠计算方法引入到电力系统的各种计算,以避免计算机浮点算法的有限精度问题及处理不确定参数所带来的难题。介绍了基于区间算法和泰勒模型的可靠计算基本原理,讨论了可靠计算在电力系统中潮流计算、时域仿真、配电系统和电力市场等领域的应用,同时也指出可靠计算的保守性问题仍是困扰其得到广泛应用的主要障碍之一。     

TTA计算软件在线路斜塔中的应用

根据云南某220kV送电线路改造中,采用TTA计算斜塔的工程实践,提出几点在计算过程中异于直立铁塔的思考。     

A new core

This article discusses motors for compressors in domestic air conditioners, an area in which there is a strong demand for high efficiency and also reports the results of the efficiency improvement and productivity of a new core structure. An innovative core structure and manufacturing method boosts efficiency of permanent-magnet motors. This article presents the close relationship between the motor characteristics and the manufacturing method and indicates a way to improve both motor characteristics and the productivity. To pursue further improvement in motor performance by improving the coil space factor further using the joint-lapped core and manufacturing cores with smaller magnetic resistance.     

光纤复合架空地线光缆光单元结构性能分析

针对不同结构类型的光纤复合架空地线(0PCW)光缆，从抗“氢损”、耐水解、抗腐蚀、短路时耐高温、低温和弯曲性能、抗侧压、光缆接续等七个方面，对0PGW光缆中金属管和螺旋塑料管这两类光单元结构的性能，进行分析和比较。     

Effect of boric acid mass transfer on the accumulation thereof in a fuel core under emergency modes at NPPs with WMR

Boric acid mass transfer processes in the reactor facilities with WMR are considered for the case of an emergency with breaking of the main circulation pipeline (MCP) and the operation of the passive safety systems, such as first-, second-, and third-stage accumulator tank systems, and a passive heat removal system (PHRS). Calculation results are presented for a change in the boric acid concentration in the fuel core (FC) of a water-moderated reactor (WMR) in the case of an emergency process. The calculations have been performed for different values of drop entrainment of boric acid from the reactor (0, 0.2, 2%). A substantial excess of the maximum concentration of boric acid has been found to occur 24 hours after an emergency event with a break of MCP. It is shown that increasing the droplet entrainment of boric acid causes the crystallization and accumulation thereof in the FC to become slower. The mass of boric acid deposits on the elements of internals is determined depending on the values of drop entrainment. These results allow one to draw a conclusion concerning the possibility of accumulation and crystallization of boric acid in the FC, because the latter event could lead to a blocking of the flow cross section and disturbance in the heat removal from fuel elements. A review of available literature data concerning the thermal properties of boric acid solution (density, viscosity, thermal conductivity) is presented. It is found that the available data are of quite a general character, but it does not cover the entire range of parameters (temperature, pressure, acid concentrations) inherent in a possible emergency situation at nuclear power plants with WMR. It is demonstrated that experimental study of boric acid drop entrainment at the parameters inherent in the emergency mode of WMR operation, as well as the studies of boric acid thermal properties in a wide range of concentrations, are required.