Fault diagnosis for analog circuits based on chaotic signal excitation     

Hong-Guang Ma  Xiao-Fei Zhu  Ming-Shun Ai  Ji-Dong Wang 《Journal of The Franklin Institute》2007,344(8):1102-1112

A fault diagnosis method for analog circuit is proposed in this paper. An all-purpose amplifier is taken as the typical circuit under test (CUT). The chaotic signal, which is generated by an improved Chua's circuit, is employed as the excitation signal of CUT. The algorithm for phase-space reconstruction of chaotic time series is a combination algorithm of multiple autocorrelation and Γ-test. The circuit state is estimated based on detecting the geometric change of Chua's attractor with a data-mining approach. For the purpose of information fusion, another eight features are extracted from the testing data to comprehensively determine the CUT states. A discussion is made for comparing the effectiveness of each feature according to the testing results.  相似文献   

A citation-based document retrieval system for finding research expertise     

Quan Thanh Tho  S.C. Hui  A.C.M. Fong 《Information processing & management》2007

Current citation-based document retrieval systems generally offer only limited search facilities, such as author search. In order to facilitate more advanced search functions, we have developed a significantly improved system that employs two novel techniques: Context-based Cluster Analysis (CCA) and Context-based Ontology Generation frAmework (COGA). CCA aims to extract relevant information from clusters originally obtained from disparate clustering methods by building relationships between them. The built relationships are then represented as formal context using the Formal Concept Analysis (FCA) technique. COGA aims to generate ontology from clusters relationship built by CCA. By combining these two techniques, we are able to perform ontology learning from a citation database using clustering results. We have implemented the improved system and have demonstrated its use for finding research domain expertise. We have also conducted performance evaluation on the system and the results are encouraging.  相似文献   

计算机实验室管理系统安全策略探讨     

郭岗  宋铭利  刘新向 《科技广场》2005,(8):34-36

本文讨论了计算机实验室管理系统中安全方面存在的问题，并从服务器安全、网络安全、数据通信安全和数据库安全等几个方面进行了分析研究，提出了防止计算机实验室管理系统中数据被非法窃取、篡改的几种安全措施，消除了计算机实验室管理系统中潜在的安全隐患问题。  相似文献   

对XML存取的研究与实现     

邹国华 《科技广场》2005,(12):64-66

该文着重研究了XML的索引结构，并对XML数据库的存取提出了自己的观点。构造了对XML这种半结构化文档建立索引和查询时采用的数据结构和算法。  相似文献   

油田远程智能电机群控系统的研究     

张咏军  王航宇 《科技广场》2007,(9):166-168

抽油机是石油开采中必须使用的设备,而电动机又是抽油机不可或缺的重要部分。根据电机在油田生产中的使用情况,采用无线电机群控系统方案,用于监测、保护和控制电机。本文对智能电机监控器的基本功能如电机参数的采集、电机保护、输出控制、数据传输等电路的设计原理和控制软件设计方法作了详细的阐述和认真的研究。  相似文献   

决策树分类算法研究综述   总被引：4，自引：0，他引：4  

季桂树  陈沛玲  宋航 《科技广场》2007,(1):9-12

本文基于决策树分类算法的研究现状,重点介绍了一些极具代表性的算法,包括ID3、C4.5等,对各种决策树分类算法的基本思想进行阐述,分析比较各种典型算法的优点和不足,并对决策树分类算法所面临的问题进行了简要的阐述,为数据分类研究者提供借鉴。  相似文献   

浅谈XML与HTML和关系数据库的比较     

陈丽冰 《中国科技信息》2005,(18):33

XML技术作为一门新兴技术,在许多领域得到广泛的支持并有着广阔的应用前景,其与HTML以及关系数据库之间的关系是值得探讨的。本文得出结论:XML并不是要替代HTML和关系数据库。HTML、关系数据库及XML将凭借各自的特点继续适用于其合适的领域。  相似文献   

Changes in parental depression symptoms during family preservation services     

Chaffin M  Bard D 《Child abuse & neglect》2011,35(6):448-458

Objectives

Parental depression symptoms often change over the course of child welfare family preservation and parenting services. This raises the question of whether certain processes in family preservation services might be associated with depression symptom change. This study tests three correlational models of change among family preservation service participants: (a) changes in depression symptoms are one facet of broad general changes in wellbeing; (b) the quality of the home visitor-client relationship is associated depression symptom changes; and (c) linking parents to adjunctive services is associated with symptom changes.

Methods

Participants were 2,175 parents in family preservation services, largely for child neglect, who were surveyed using standard measures at pre-treatment, post-treatment and 6 month follow-up. Change patterns were evaluated using growth models, including bivariate parallel and multivariate second-order models.

Results

Parallel growth was noted among depression symptoms and changes in social, economic, familial, and parenting domains. A second order change model positing a global change pattern fit the data well. Working alliance had a modest association with improvement, but successful linkage to outside mental health services was not associated with improvement.

Conclusions

Changes in diverse indicators of wellbeing follow a global pattern which might support use of less complex rather than more fully comprehensive service plans. Findings about lack of adjunctive usual care mental health service benefit may be related to uncontrolled factors and this is a topic in need of additional study.  相似文献   

2009—2010年国外数字资源长期保存模式分析及启示   总被引：1，自引：0，他引：1  

林强 《图书馆建设》2011,(3):1-4

对2009—2010年国外数字资源长期保存项目的分析发现,数字资源保存模式对数字资源保存活动的开展具有积极的引导与评估作用。我国数字资源长期保存工作应注意:作为组织者,建立和健全一套行之有效的方针政策与做出正确的决策是其首当其冲的任务,实现与合作者之间的良好沟通与合作是开展数字资源保存项目的基础,获得或者募集资金是开展工作的先决条件;在技术环节上,要充分考虑到被保存资源的客观状态,利用现有技术进行保存,并且要充分考虑到资源前后格式上的变化及未来资源所处的技术环境;在维护与评估上,积累经验并正确评估是十分必要的。  相似文献   

多维多息特征数据挖掘方法研究——以中药指纹图谱数据为例   总被引：1，自引：0，他引：1  

童逸夫  黄春毅 《现代图书情报技术》2011,(12):69-73

利用R开源统计分析软件平台,以中药HPLC指纹图谱数据为例,构建多维多息特征数据挖掘模型并进行可视化处理分析,研究结果显示主成分分析降维后的综合主成分能够反映多维多息特征数据的规律,并且验证主成分聚类模型及神经网络模型用于揭示多维多息数据的信息特征的有效性与实用性。最终根据主成分聚类分析结果,建立未知产地川芎样晶的产地预测鉴别模型,从而为川芎质量控制提供参考  相似文献