应用ATM网络实现电力系统远程实时监控

提出了电力系统实时决策系统中超远程强实时通信的设计与实现方法，在网络拓扑上采用星形的多智能客户机组／中央服务器群集模式；网络物理载体采用能够提供高带宽和极短时延的基于光放大技术的同步光纤网；在通信方式的选择上，采用基于无确认的方式并且能够提供良好的实时服务的兼容性的ATM技术，通过对可靠性和实时通信时延进行精确估算，表明采用此设计方式，可以满足电力系统实时决策和紧急控制对上千千米超远程通信的可靠性和实时性要求。     

用多个对应的后向神经网络进行同杆双回线故障识别及测距的模式

电力系统高压同杆双回输电线的应用日益增多，但其故障识别与测距的问题尚未完全解决，同杆双回线因存在回路间耦合等因素，使得用单一的神经网络进行故障识别与测距的结果并不理想。作者比较分析了BP网络与Kohonen网络在同杆双回线测距方面的优缺点，提出了将故障识别与测距任务分配到多个网络的方法即将同杆双回线的每种故障模式各与一个BP人工神经网络对应，在线路上取一些固定点作为标志点，训练成功的BP网络输出的模糊值代表了标志点上发生故障的可能性。用模糊值构成插值曲线，根据曲线的相对位置确定故障模式，并由曲线的最小值求得故障距离。大量仿真表明该法可以准确可靠地确定故障模式并能测得较高的测距精度。     

Properties of composition sinter prepared from fibrous barium titanate and nanometer zirconia

0　ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｒｅｓｅａｒｃｈｏｎｎａｎｏｃｏｍｐｏｓｉｔｅｓｍａｔｅｒｉａｌｓｈａｓｂｅ ｃｏｍｅａｎｅｗｓｔｕｄｙｆｏｃｕｓｉｎｒｅｃｅｎｔｙｅａｒｓ[1] .Ｔｈｅｃｏｍ ｐｏｓｉｔｅｓａｒｅｃｏｍｂｉｎｅｄｗｉｔｈｐａｒｔｉｃｌｅ ｐａｒｔｉｃｌｅ[2 ] ,ｏｒｐａｒ ｔｉｃｌｅ ｆｉｂｅｒ[3] .Ｔｈｅｓｔｕｄｙｏｎｂａｒｉｕｍｔｉｔａｎａｔｅｃｏｍｐｏｓｉｔｅｓｉｓｗｉｄｅｓｐｒｅａｄａｎｄａｇｒｅａｔｐｒｏｇｒｅｓｓｈａｓｂｅｅｎｍａｄｅ .Ｂｕｔｉｔｉｓｏｎｌｙｌｉｍｉｔｅｄｉｎ…     

光电测距导线中测角和量边的合理精度

论证了光电测距导线中“等影响”原则的不合理性,提出了角度测量和边长测量的合理精度。     

风扇座注塑模设计

分析了风扇座的工艺性 ,介绍了风扇座注射模结构 ,并指出设计、制造过程中应特别注意的问题     

基于Web的多媒体教学系统的设计与实现

探讨了计算机网络技术在现代教学中的应用,就基于Web的多媒体教学系统的功能和系统结构进行了较为深入的研究,详细地阐述了设计网络多媒体教学系统的关键技术及实现方法.     

An n-gram-based approach for detecting approximately duplicate database records

Detecting and eliminating duplicate records is one of the major tasks for improving data quality. The task, however, is not as trivial as it seems since various errors, such as character insertion, deletion, transposition, substitution, and word switching, are often present in real-world databases. This paper presents an n-gram-based approach for detecting duplicate records in large databases. Using the approach, records are first mapped to numbers based on the n-grams of their field values. The obtained numbers are then clustered, and records within a cluster are taken as potential duplicate records. Finally, record comparisons are performed within clusters to identify true duplicate records. The unique feature of this method is that it does not require preprocessing to correct syntactic or typographical errors in the source data in order to achieve high accuracy. Moreover, sorting the source data file is unnecessary. Only a fixed number of database scans is required. Therefore, compared with previous methods, the algorithm is more time efficient. Published online: 22 August 2001     

Reasoning About Distance Based on Fuzzy Sets

Most computer systems that deal with issues of space reason about distance by using a metric. For example, most geographic information systems apply the euclidean metric, requiring all subjects to adhere to the same view of space. As a result, dealing with imprecise or uncertain geographic information becomes difficult or sometimes even impossible. In this paper, we describe a way of reasoning about distance that is not restricted to euclidean geometry. The idea is to use fuzzy sets to describe how close objects are to each other.     

Fully Scalable Fault-Tolerant Simulations for BSP and CGM

In this paper we consider general simulations of algorithms designed for fully operational BSP and CGM machines on machines with faulty processors. The BSP (or CGM) machine is a parallel multicomputer consisting of p processors for which a memory of n words is evenly distributed and each processor can send and receive at most h messages in a superstep. The faults are deterministic (i.e., worst-case distributions of faults are considered) and static (i.e., they do not change in the course of computation). We assume that a constant fraction of processors are faulty.  We present two fault-tolerant simulation techniques for BSP and CGM:  1. A deterministic simulation that achieves O(1) slowdown for local computations and O((log_h p)²) slowdown for communications per superstep, provided that a preprocessing is done that requires O((log_h p)²) supersteps and linear (in h) computation per processor in each superstep.  2. A randomized simulation that achieves O(1) slowdown for local computations and O(log_h p) slowdown for communications per superstep with high probability, after the same (deterministic) preprocessing as above.  Our results are fully scalable over all values of p from Θ(1) to Θ(n). Furthermore, our results imply that if pn for 0<<1 and h=Θ((n/p)^δ) for 0<δ1 (which hold in almost all practical BSP and CGM computations), algorithms can be made resilient to a constant fraction of processor faults without any asymptotic slowdown.     

基于双阈值法的超声辊型在线检测的研究

To eliminate the error of distance measurement caused by amplitude change from signal attenuation, the method based on dual thresholds is introduced． Thus the precise ultrasonic measurement is accomplished． Combining wiht the mechanical scanning the on-line detection of roller shape is implemented．