Soft computing approach to fault diagnosis of centrifugal pump

Fault detection and isolation in rotating machinery is very important from an industrial viewpoint as it can help in maintenance activities and significantly reduce the down-time of the machine, resulting in major cost savings. Traditional methods have been found to be not very accurate. Soft computing based methods are now being increasingly employed for the purpose. The proposed method is based on a genetic programming technique which is known as gene expression programming (GEP). GEP is somewhat a new member of the genetic programming family. The main objective of this paper is to compare the classification accuracy of the proposed evolutionary computing based method with other pattern classification approaches such as support vector machine (SVM), Wavelet-GEP, and proximal support vector machine (PSVM). For this purpose, six states viz., normal, bearing fault, impeller fault, seal fault, impeller and bearing fault together, cavitation are simulated on centrifugal pump. Decision tree algorithm is used to select the features. The results obtained using GEP is compared with the performance of Wavelet-GEP, support vector machine (SVM) and proximal support vector machine (PSVM) based classifiers. It is observed that both GEP and SVM equally outperform the other two classifiers (PSVM and Wavelet-GEP) considered in the present study.     

基于IEC61131-3标准的PLC编辑模块设计与实现

基于IEC61131-3标准设计一个可编程逻辑控制器（PLC）编辑模块,并给出了主要数据结构和算法的设计。通过测试表明用户界面友好,操作简单,对后续开发具指导意义。     

A parallel Monte Carlo search algorithm for the conformational analysis of polypeptides

In recent years several approaches have been proposed to overcome the multiple-minima problem associated with nonlinear optimization techniques used in the analysis of molecular conformations. One such technique based on a parallel Monte Carlo search algorithm is analyzed. Experiments on the Intel iPSC/2 confirm that the attainable parallelism is limited by the underlying acceptance rate in the Monte Carlo search. It is proposed that optimal performance can be achieved in combination with vector processing. Tests on both the IBM 3090 and Intel iPSC/2-VX indicate that vector performance is related to molecule size and vector pipeline latency.     

A Further Comparison of Splitting Rules for Decision-Tree Induction

One approach to learning classification rules from examples is to build decision trees. A review and comparison paper by Mingers (Mingers, 1989) looked at the first stage of tree building, which uses a splitting rule to grow trees with a greedy recursive partitioning algorithm. That paper considered a number of different measures and experimentally examined their behavior on four domains. The main conclusion was that a random splitting rule does not significantly decrease classificational accuracy. This note suggests an alternative experimental method and presents additional results on further domains. Our results indicate that random splitting leads to increased error. These results are at variance with those presented by Mingers.     

特种车辆维修空间可达性评价方法研究

可达性作为维修性的定性指标,缺少定量评价的方法。传统方法只针对装备的整体进行定性评价,不能对不同的等级维修和单个维修动作进行评价。通过对维修性设计中的结构性因素进行分析,得到了空间可达性的主要影响因素。在虚拟维修仿真平台的基础上对工具旋转角度和作业空间比进行了量化评分,给出了针对维修作业过程中单个零部件拆卸的空间可达性评价方法。单个动作评价方法为等级维修的整体空间可达性评价提供了数据基础,并为新型特种车辆的维修方案论证和研制的空间可达性评价提供了手段。     

航空发动机传感器故障鲁棒检测方法

研究发动机传感器故障准确检测问题,现代航空发动机数字电子控制系统对传感器的可靠性要求日益提高。针对航空发动机结构复杂,又工作在高温和高压下,常规采用的传感器故障检测方法的准确性易受到建模误差与外界扰动的影响,造成漏报或误报。为了提高检测精度,提出建立航空发动机数控系统传感器未知输入故障模型,采用特征结构配置的方法,通过配置闭环系统左特征向量实现故障检测残差对不确定性因素的干扰解耦,降低扰动对故障诊断结果的影响。用某型涡扇发动机数控系统传感器故障数字仿真试验表明,所设计的方法对范数有界的不确定量可以实现干扰解耦,抑制干扰对故障检测的影响,改善检测算法的鲁棒性,提高检测结果的准确性,同时满足在线运算的实时性要求。提高了航空发动机的可靠性,保证了安全飞行。     

基于复杂网络理论的高校内部理工医文合作研究分析

运用复杂网络理论的基本原理和有关方法,对理工医文等学科、专业之间的合作规律和人员合作方式进行探讨,以某高校2005-2010年医工合作情况作为实例展开研究,采用5年的合作数据作了计算分析,研究了高校内部理工医文开展学科交叉工作的特点及其运行情况、医工交叉合作中存在问题,客观分析其原因,提出了解决的办法,为今后开展高校系统的理工医文交叉合作,建设电子化交叉平台.     

基于STM32的逆变弧焊电源控制器设计

数字化是弧焊电源的发展趋势,其关键在于控制器的数字化。目前市场上的大多数数字化产品价格相对高昂,采用STM32系列单片机进行经济型数字化弧焊电源控制器的设计和实现。该控制器采用数字式PI方法进行输出电流控制,并具有按键操作、液晶显示、过流保护、过热保护等功能。该控制器还具有良好的扩展I}生,可以通过修改程序增强系统功能。     

电力信息自动化系统中Web技术时间应用分析

在我国的变电所的分布不是非常集中,并且变电的设备也较多,因此精确管理难度和宏观调度都有很大的增加。WEB技术可以使得非常简单的浏览和开发信息,并且可以使得变电所之间的信息交流便得增加,因此电力信息自动化系统的WEB技术应用越来越广泛。     

A faster divide-and-conquer algorithm for constructing delaunay triangulations

An easily implemented modification to the divide-and-conquer algorithm for computing the Delaunay triangulation ofn sites in the plane is presented. The change reduces its (n logn) expected running time toO(n log logn) for a large class of distributions that includes the uniform distribution in the unit square. Experimental evidence presented demonstrates that the modified algorithm performs very well forn2¹⁶, the range of the experiments. It is conjectured that the average number of edges it creates—a good measure of its efficiency—is no more than twice optimal forn less than seven trillion. The improvement is shown to extend to the computation of the Delaunay triangulation in theL _p metric for 1<p.This research was supported by National Science Foundation Grants DCR-8352081 and DCR-8416190.