电网故障诊断的一种完全解析模型

现代大规模互联电网提高了电力系统运行的稳定性和经济性,同时也给电网的故障诊断增加了难度。对电网保护配置和断路器动作规则进行深入分析,提出一种新的电网故障诊断模型——完全解析模型,并为基于此模型的故障诊断提出一种实用有效的求解方法。在完全解析模型中,故障假说（即可疑故障设备的故障情况）与保护、断路器的动作情况及拒动和误动情况一同表示成逻辑变量,而保护配置和断路器动作规则以逻辑方程组形式进行充分表达,逻辑方程组的每个解析解对应一个故障模式（设备故障状态和保护动作、断路器跳闸状态及拒动/误动情况）,是对故障情形的完整解释。本模型对故障诊断规则和保护、断路器的动作逻辑进行完全解析,并完整保留了故障设备、保护动作和断路器跳闸之间的耦合关系,克服了已有解析模型的缺陷。算例表明,保留完整耦合关系的完全解析模型可有效提高故障诊断的准确性和容错能力。     

Cooperative warning systems: The impact of false and unnecessary alarms on drivers’ compliance

Cooperative warning systems have a great potential to prevent traffic accidents. However, because of their predictive nature, they might also go along with an increased frequency of incorrect alarms that could limit their effectiveness. To better understand the consequences associated with incorrect alarms, a driving simulator study with N = 80 drivers was conducted to investigate how situational context and warning urgency jointly influence drivers’ compliance with an unreliable advisory warning system (AWS). The participants encountered several critical urban driving situations and were either assisted by a 100% reliable AWS, a 60% reliable AWS that generated false alarms (without obvious reason) or a 60% reliable AWS that generated unnecessary alarms (with plausible reason). A baseline drive without any assistance was also introduced to the study. The warnings were presented either only visually or visual-auditory. In line with previous research, drivers’ compliance and effectiveness of the AWS was reduced by false alarms but not by unnecessary alarms. However, this so-called cry wolf effect (Breznitz, 1984) was only found in the visual-auditory condition, whereas there was no effect of warning reliability in the condition with visual AWS. Furthermore, false but not unnecessary alarms caused the participants to rate the AWS less favourably during a follow-up interview. In spite of these negative effects of false alarms, a reduction in the frequency of safety-critical events (SCEs) and an earlier braking onset were evident in all assisted drives compared with that of non-assisted driving, even when the AWS was unreliable. The results may thus lower concerns about the negative consequences of warning drivers unnecessarily about upcoming traffic conflicts if the reasons of these alarms are comprehensible. From a perspective of designing AWS, we recommend to use less urgent warnings to prevent the cry wolf effect.     

基于模糊动态聚类的入侵检测

为了提高入侵检测系统对入侵特征知识的归纳和概括能力,提出了将一种基于模糊等价关系的动态聚类方法应用于对入侵特征集进行层次聚类。实验证明该方法提高了系统识别未知入侵行为的能力,并且通过动态调整参数能使检测在误警率和检测率中达到较好的 平衡。     

Requirements for sequential flow and static image analysis—a preliminary study

The hybridization of flow and image analysis in the prescreening of gynecological smears combines the advantages of both methods. Taking the Heidelberg flow analysis system (HEIFAS) as an example the prerequisites of a successful combination of both systems are presented: (a) preservation of cell morphology; (b) avoidance of preferential cell loss; (c) ability to restain sorted cells; and (d) recognition of false alarms at high resolution. Two TV-based imaging instruments have been applied to cells sorted by two-parameter flow cytometry. Both instruments operating in the absorption mode (FAZYTAN) as well as in the fluorescence mode (LEYTAS) allow the detection of false alarms in flow. This preliminary study shows, that a discrimination of false alarms and true suspicious cells was found to be possible.     

Accelerated testing of on‐board diagnostics

Modern products frequently feature monitors designed to detect actual or impending malfunctions. False alarms (Type I errors) or excessive delays in detecting real malfunctions (Type II errors) can seriously reduce monitor utility. Sound engineering practice includes physical evaluation of error rates. Type II error rates are relatively easy to evaluate empirically. However, adequate evaluation of a low Type I error rate is difficult without using accelerated testing concepts, inducing false alarms using artificially low thresholds and then selecting production thresholds by appropriate extrapolation, as outlined here. This acceleration methodology allows for informed determination of detection thresholds and confidence in monitor performance with substantial reductions over current alternatives in time and cost required for monitor development. Copyright © 2006 John Wiley & Sons, Ltd.     

An online method to remove chattering and repeating alarms based on alarm durations and intervals

Chattering and repeating alarms, which repeatedly make transitions between alarm and non-alarm states without operators’ response, are the most common form of nuisance alarms encountered in industrial plants. The paper formulates two novel rules to detect chattering alarms caused by random noise and repeating alarms by regular patterns such as oscillation, and proposes an online method to effectively remove chattering and repeating alarms via the m-sample delay timer. Industrial examples are provided to support the formulated rules and to illustrate the effectiveness of the proposed method.     

火灾自动报警系统误报原因分析及对策

介绍火灾自动报警系统产生误报的各种原因,找出了发生误报警的根本所在,并结合实际对解决误报问题提出了相应对策。     

Hallucinations, Negative Symptoms, and Response Bias in a Verbal Recognition Task in Schizophrenia.

Several studies have reported an association between hallucinations and tendency to make false alarms in acoustic signal detection tasks. Previous work on patients with schizophrenia has suggested that false recognitions and other types of memory error were positively associated with hallucinations and inversely associated with certain negative symptoms of withdrawal. In this study, 40 patients with schizophrenia were administered a word recognition task. Mixed lists of high- and low-frequency words were presented, then the target words had to be recognized among distractors in immediate and delayed recognition conditions. Hallucination scores were correlated with an increased bias toward false recognitions of nonpresented words. Affective flattening tended to be correlated with a reduced bias toward false recognitions. Anhedonia was significantly correlated with a reduced response bias. Hallucinations and anhedonia therefore presented an opposite association with the response bias. The influence of word frequency and delay on this association is discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

An A Contrario Decision Method for Shape Element Recognition

Shape recognition is the field of computer vision which addresses the problem of finding out whether a query shape lies or not in a shape database, up to a certain invariance. Most shape recognition methods simply sort shapes from the database along some (dis-)similarity measure to the query shape. Their main weakness is the decision stage, which should aim at giving a clear-cut answer to the question: “do these two shapes look alike?” In this article, the proposed solution consists in bounding the number of false correspondences of the query shape among the database shapes, ensuring that the obtained matches are not likely to occur “by chance”. As an application, one can decide with a parameterless method whether any two digital images share some shapes or not.     

智能化系统在住宅小区的应用

本文通过对智能化系统中闭路监控系统、电子巡更系统、可视对讲系统、家庭住户报警系统结构及功能分析,探索智能化系统的合理配置和优化组合,以期达到智能建筑先进性、实用性和经济性的目的。