A survey of efficiency-estimation methods for in-service induction motors

Condition monitoring of electric motors avoids severe economical losses resulting from unexpected motor failures and greatly improves the system reliability and maintainability. Efficiency estimation, which shares many common requirements with condition monitoring in terms of data collections, is expected to be implemented in an integrated product. This brings more considerations into the selection of the efficiency-estimation methods. This paper presents the results of an up-to-date literature survey on efficiency-estimation methods of in-service motors, particularly with considerations of the motor-condition-monitoring requirements. More than 20 of the most commonly used methods are briefly described and classified into nine categories according to their physical properties. Six categories of these methods are more related to in-service testing and are compared in a table summarizing the required tests and measurements, intrusion level, and average accuracy. Estimation of the rotor speed and the stator resistance, the two stumbling blocks of various efficiency-estimation methods, is also carefully studied; commonly used methods are summarized. Based on the survey results, four efficiency-estimation methods are suggested as candidates for nonintrusive in-service motor-efficiency estimation and condition-monitoring applications. Another contribution of this paper is that a general approach for developing nonintrusive motor-efficiency-estimation methods is proposed, incorporating rotor speed, stator resistance, and no-load loss estimations.     

恰希玛核电站二期工程核岛基坑降水与回灌技术

恰希玛核电站二期工程核岛基坑降水与回灌，没有可供参考的先例。本文阐述了降水与回灌所经历的过程、改进措施以及最后取得的成果，总结了与回灌技术相关的经验教训，为类似的大型工程提供借鉴。     

Simultaneous all-optical inverted and noninverted wavelength conversion using a single-stage fiber-optical parametric amplifier

We have demonstrated, for the first time to our knowledge, simultaneous all-optical inverted and noninverted wavelength conversion by using a single-stage two-pump fiber-optical parametric amplifier with an extinction ratio between 7 and 14 dB over 24 nm.     

九江市矿产资源开发利用现状与对策

分析了江西省九江市矿产资源的基本特点、开发利用现状及存在的问题,提出了九江市科学开发利用矿产资源的对策.     

Reconfigurable Web wrapper agents

Web wrapper agents exploit online Web data sources, facilitating information integration and reuse. With the DeepSpot Agent Toolbox, users can automate virtually all types of Web browsing sessions simply by browsing the target Web sites.     

顾及多个因子的卡尔曼滤波法在大坝变形分析中的应用

首先建立大坝变形与时间相关关系的变形模型，从中找出变形与时间相关关系的最佳变形模型;然后考虑到库水位和温度对大坝变形的影响，建立变形与时间、水位、温度相关关系的变形模型;最后将变形与时间、水位、温度相关关系的变形模型的模型参数作为状态向量，用卡尔曼滤波法进行大坝变形分析。实例计算表明这种建模方法效果较好。     

高分子功能材料及在传感器中的应用一高分子功能材料种类和功能(连载一)

简要介绍了高分子功能材料种类及信息转换功能，并对其导电性、光电性、压电性和热电性进行了论述。     

添加晶种对硅酸盐水泥生料易烧性影响的研究

采用实验室制备不同种类单矿物，纯熟料及白水泥熟料为晶种，利用ＤＴＡ，ＸＲＤ及测定游离石灰等方法，研究了其对硅酸盐水泥生料易烧性的影响。结果表明；铁相的作用在四种单矿物中最为明显，其它三种主要矿物也均有不同程度地促进煅烧过程的熟料矿物形成的作用。     

A novel method of structural shape optimization coupling BEM with an optimization method based on biological growth

Local stress peaks are the main reason for fatigue failure of structures, and therefore many researchers make every effort to search for effective methods of structural shape optimization. Mattheck and Burkhard (1990) have developed a method by simulating the self-optimization mechanism of biological growth, using FEM. BEM is a very effective method in which only the boundary is divided into elements, and particularly, accurate results at the boundary can be obtained. It is obvious that BEM is a more suitable analysis method for structural shape optimization than FEM. Coupling BEM of three-dimensional thermoelasticity problems with an optimization method based on biological growth, a novel method of structural shape optimization is successfully developed by the authors. Several examples are used to demonstrate that the method is successful and efficient.