传感器影响可燃气体报警器长期稳定性及产生误报的原因分析

概述了影响报警产品性能的两大原因-电路和气体传感器,其中气体传感器部分是影响质量的关键。以半导体传感器为例,分析了可燃气体报警器在正常使用环境下经常发生误报警及使用一段时间后不报警的原因,并采取了相应的措施—通过对传感器增加干扰气体过滤帽把主要影响报警器误报的乙醇等气体滤除掉,并尽可能远离含硅物质以保证传感器的长期稳定性。根据对不同质量传感器在各种气体环境下的试验数据及特性曲线分析,论述了传感器对报警产品的可靠性及长期稳定性的影响,并针对报警器的误报问题提出相应的解决方法。     

Enhanced long-term stability of SnO2-based CO gas sensors modified by sulfuric acid treatment

The gas-sensing properties and long-term transients of SnO₂-based CO gas sensors modified by sulfuric acid treatments have been investigated. The sulfuric acid treatments are carried out in two ways: kneading of SnO₂ powders with a sulfuric acid solution or dipping of the sintered sensor element in the same solution. Both sulfuric acid treatments enhance the sensitivity to CO and H₂, although the enhancement is more remarkable with the dipping treatment. The effects of these treatments on the selectivity to CO and some parameters relating to the reversibility and accuracy for CO detection are also evaluated. Furthermore, the long-term stabilities of the modified and unmodified sensor elements for over 550 days are investigated. The results indicate that the dipping treatment significantly improved the stability and reliability of the SnO₂-based CO gas sensor.     

气体传感器试验分析系统

在分析研究了电子鼻的基本原理和系统组成的基础上,建立了气体传感器(7ST/F,7NDH)流量静态数学模型和试验分析测试系统,对其输入-输出特性进行了试验测试,并用Matlab对试验数据进行了分析与研究。通过试验,验证了模型的正确性及分析测试系统的通用性,获得了具有应用价值的结果,为后续的模式识别技术和人工神经网络技术的应用打下了基础。     

多变体执行误报问题分析与解决方法综述

从安全角度出发,多变体执行（multi-variant execution,MVX）被广泛应用于网络安全防御,但多变体执行存在一个共性问题：即各路执行体向裁决器返回内容时,合路产生的误报难以解决。排除机器环境等客观因素,产生误报是因为表决器收到合路信息后开始对非一致变量作安全判断,除真实攻击造成的非一致变量外,还夹杂着正常系统运行产生的非一致变量（如内存描述符、端口号、随机数、代码及进程内的线程调用顺序）,从而造成表决器误判,影响多变体系统正常运行。如果能降低多变体执行的误报率,则可以有效地提高系统效率及防御能力。对近年来多变体执行的类型进行归类,并对多变体执行产生的误报问题及解决策略进行归纳总结,分析多变体执行产生裁决误报的原因,选择Pina算法进行同步的策略、编译器模块插桩的策略、缩小表决边界的策略,对三种方案在特定应用场景下进行实验分析,分析每个方法的功能及性能,指出各自策略的优点及缺点。最后讨论现有多变体执行现有技术未解决的难点和未来的研究方向。     

Fault management in supervisory control: the effect of false alarms and support

Automation has changed the role of human operators from direct manual control to supervision. Their main task is to monitor whether system performance remains within pre-specified ranges and intervention is only required in unusual situations. One of the consequences is a loss of situation awareness, which significantly affects performance in abnormal, time-critical situation. The present study reports two experiments, both dealing with fault management in a maritime supervisory control task. The first experiment investigated to what extent false alarms would affect performance and diagnosis behaviour when multiple disturbances occurred. Thirty-nine students from maritime curricula diagnosed disturbances that could either be real or turn out to be a false alarm. The presence of false alarms not only affected the rate with which the subsystems under control were sampled, but it also increased problem-solving time. One of the reasons for suboptimal performance in dealing with fault propagation was tunnel vision: participants had a tendency to deal with disturbances sequentially. In the second experiment the effect of support on performance and diagnosis behaviour was investigated. Two types of support were distinguished: interactive support requiring participants to provide the symptom values and automatic support that directly provided the correct action. Thirty students from maritime curricula diagnosed disturbances with the help of either the interactive or the noninteractive support tool. The results indicated that even though both support tools gave the same advice on how to act, more incorrect actions were taken in the non-interactive support condition. Even though no differences in performance were found after the tool had been removed, it was shown that participants who were used to interactive support used a more structured problem-solving strategy than participants used to the non-interactive support. Consequences for system design are discussed.     

Fault management in supervisory control: the effect of false alarms and support

Automation has changed the role of human operators from direct manual control to supervision. Their main task is to monitor whether system performance remains within pre-specified ranges and intervention is only required in unusual situations. One of the consequences is a loss of situation awareness, which significantly affects performance in abnormal, time-critical situation. The present study reports two experiments, both dealing with fault management in a maritime supervisory control task. The first experiment investigated to what extent false alarms would affect performance and diagnosis behaviour when multiple disturbances occurred. Thirty-nine students from maritime curricula diagnosed disturbances that could either be real or turn out to be a false alarm. The presence of false alarms not only affected the rate with which the subsystems under control were sampled, but it also increased problem-solving time. One of the reasons for suboptimal performance in dealing with fault propagation was tunnel vision: participants had a tendency to deal with disturbances sequentially. In the second experiment the effect of support on performance and diagnosis behaviour was investigated. Two types of support were distinguished: interactive support requiring participants to provide the symptom values and automatic support that directly provided the correct action. Thirty students from maritime curricula diagnosed disturbances with the help of either the interactive or the noninteractive support tool. The results indicated that even though both support tools gave the same advice on how to act, more incorrect actions were taken in the non-interactive support condition. Even though no differences in performance were found after the tool had been removed, it was shown that participants who were used to interactive support used a more structured problem-solving strategy than participants used to the non-interactive support. Consequences for system design are discussed.     

Decision-making and response strategies in interaction with alarms: the impact of alarm reliability,availability of alarm validity information and workload

Responding to alarm systems which usually commit a number of false alarms and/or misses involves decision-making under uncertainty. Four laboratory experiments including a total of 256 participants were conducted to gain comprehensive insight into humans' dealing with this uncertainty. Specifically, it was investigated how responses to alarms/non-alarms are affected by the predictive validities of these events, and to what extent response strategies depend on whether or not the validity of alarms/non-alarms can be cross-checked against other data. Among others, the results suggest that, without cross-check possibility (experiment 1), low levels of predictive validity of alarms ( ≤ 0.5) led most participants to use one of two different strategies which both involved non-responding to a significant number of alarms (cry-wolf effect). Yet, providing access to alarm validity information reduced this effect dramatically (experiment 2). This latter result emerged independent of the effort needed for cross-checkings of alarms (experiment 3), but was affected by the workload imposed by concurrent tasks (experiment 4). Theoretical and practical consequences of these results for decision-making and response selection in interaction with alarm systems, as well as the design of effective alarm systems, are discussed.     

Managing the false alarms: A framework for assurance and verification of surveillance monitoring

This article discusses methods to support assurance of surveillance monitoring and compliance verification knowledge management (CV-KM). The discussion includes aspects of primary monitoring systems, the different environments in which they operate, the verification problem solving and decision making tasks, the problem structure, and the coordination of the review process to facilitate truth maintenance and regulatory Meta rules. Based on the ALCOD (Alert Coding) prototype developed with the Surveillance Division of the Australian Stock Exchange (ASX), the surveillance operation is considered a primary monitoring function with the analysis of the resulting output the second-tier monitoring function—the assurance component.

Instability of metal oxide-based conductometric gas sensors and approaches to stability improvement (short survey)

In the present brief review modern views on the reasons of time instability of gas sensors parameters, as well as approaches, which could be used for the improvement of this important sensor's parameter, are summarized. In particular, the influence of factors such as structure transformation, phase transformation, poisoning, degradation of contacts and heaters, bulk diffusion, errors in design, change of humidity, fluctuations of temperature in the surrounding atmosphere, and interference effect was analyzed. It was shown that while designing devices such as solid-state gas sensors, there are no secondary issues or tasks—all are important. Sensors work in extreme temperatures in the presence of active gases, and therefore every element of the sensor could be responsible for its long-term stability. The conclusions, regarding the efficiency of approaches such as optimization of technological processes and optimization of exploitation processes used for improvement of stability of conductometric metal oxide gas sensors, were made as well.     

SnO_2纳米结构气体传感器制备与气敏特性研究

由于二氧化锡(SnO_2)稳定的理化性质与优越的导电性能,制备的气体传感器具有灵敏度高、寿命长、稳定性好等特点。利用水热法制备了纳米结构SnO_2材料,进而制作旁热式气体传感器。通过调节氢氧化钠(Na OH)的量,研究不同浓度下纳米结构SnO_2材料的形貌,搭建实验平台,测试不同形貌下敏感材料的灵敏度、选择性、重复性,并分析其敏感机理。     

有毒有害可燃气体监测仪表软件设计中的几个关键细节

有毒、有害、可燃气体监测仪表在安全生产领域占有非常重要的地位。笔者以集体的长期实践经验为基础,总结了这类仪表硬、软件的一般结构;重点介绍了在软件设计中关于零点和精度处理的几个关键细节。最后还交代这些方法的参考意义。     

气体传感器的研究现状与发展趋势

传感器技术是新技术革命与信息社会的重要技术基础,是实现测试自动控制的重要环节,已深入到人类生活的各种领域.随着微电脑与微电子技术的日益普及和应用,对传感器的性能、数量及用途提出了新需求,促使对新型传感器的开发更加重视.列举了半导体、浓差电池、接触燃烧等类型的气体传感器的优缺点和当前一些重要领域中的应用,重点介绍了气体传感器的研究现状与发展趋势.     

Analysis of the aging characteristics of SnO2 gas sensors

Two types of tin oxide (SnO₂) gas sensors were synthesized, which consist of spherical SnO₂ nanoparticles and SnO₂ nanorods mixed at different ratio, and their aging processes were studied. Using the Complex Impedance Spectroscopy method the electrical properties that are related to the microscopic structure of the samples were investigated. The evolution of absorption current was measured to analyze the ionic conductance that reflects the charging states of the samples. The results indicate that devices of optimal long-term stability can be obtained by sintering the mixture of SnO₂ nanorods and spherical nanoparticles (1:1 weight ratio) at 850 °C. In the samples’ impedance data considerable fluctuation could be seen during the early stage of the aging process, which gradually disappeared after several days. The aging process, which is revealed by the changes in both grain-boundary resistance and capacitance, indicates the corresponding changes in the grain-boundary barrier height and the width of depletion layer. We suggest the DC-field-induced migration of ions within the grain boundaries as the probable cause of the phenomenon.     

便携式CO气体泄漏多模式报警仪设计与实现

针对目前气体泄露检测报警装置存在检测精度低、报警方式单一等问题,设计一种便携式CO气体泄漏报警仪.报警仪以MSP430F135芯片为控制核心,以声光、震动、短信模块为报警主体,通过CO传感器获得CO体积分数,经过数据去噪、放大、A/D转换、安全验证、报警触发和实时显示等流程完成气体泄漏的实时监测和处理.为了同时满足安装和便携两种方式,内置了外置供电和充电模块自动切换,实时显示电量和提醒充电,经过实验室测试和现场测试,该气体报警仪具有便捷、高精度、低功耗、多模式报警、操作方便等多种优点.     

纳米SiO_2掺杂的In2O_3厚膜气敏传感器稳定性研究

采用丝网印刷技术,制备了纳米SiO2掺杂的In2O3厚膜气敏传感器,并通过加速寿命试验对乙醇气氛下传感器的稳定性进行探究。通过长期测试发现纳米SiO2的掺入明显地提高了In2O3气敏传感器的稳定性。此外,当SiO2的掺杂浓度控制在5wt%左右时,In2O3气敏传感器的气敏性能也有了很大的提高。结合实验数据,对SiO2提高In2O3气敏传感器稳定性与敏感性的微观机理做了深入分析。     

通信网告警影响性分析机制的研究与应用

本地通信网由大量设备与链路相互连接组成,其中一个部件的故障可能关联多个设备和链路,从而引发大量衍生的告警.本文对通信网告警数据的相关性特征进行了详细分析,提出了告警影响性分析策略,建立了分析模型,并应用于通信网网管系统验证了其有效性.     

煤矿安全监控系统常见误报警原因分析及软件处理方法

针对煤矿安全监控系统在实际使用中由于外部干扰产生的误报警问题,分析了误报警原因,提出了一种通过上位机软件处理误报警的方法。该方法通过系统监测值的变化状态和持续时间可判断出传输线路干扰、传感器不稳定、供电不稳时产生的误报警,有效避免了误报警的产生,提高了煤矿安全监控系统的稳定性和准确性。     

一种高精度可燃气体检测报警器设计

利用半导体可燃气体传感器MQ-2设计了一种可燃性气体体积分数检测报警器,由可燃性气体传感器、模/数转换电路、单片机、显示电路、声光报警电路等组成.传感器MQ-2将气体体积分数转换为电压信号,送A/D转换电路,转换后的信号送STC89C52单片机,单片机经过处理后控制显示单元显示气体体积分数,同时控制驱动报警电路实现声光报警.实验表明:该检测报警器对异丁烷、甲烷、天然气等可燃性气体检测精度达到了0.01％,具有检测性能稳定、线性度好、电路简单、成本低、小型化、便于调试等特点.     

Simulation of police shooting stability training based on FPGA and sensors

Stability training refers to the practice, while the surface is unstable and activation stabilizer muscles of the trunk and goals, which may ignore other forms of exercise. For stability, the train network control system is caused by network latency and packet drop out of school. The current study aimed to analyze the accuracy of necessary shooting skills and check the balanced posture, stability, and rifle shooting performance bracelets. There is no burden on the body in different performance groups. No. Equivalent continuous-time model, proposed account. The train network control system model uses Romanov theory, some new analytical techniques to get in, and less conservative results. It will be completed. The effectiveness of the proposed method of numerical display. The proposed training in the correct use of architecture to shape muscle memory training interns position signal trainee lead to incorrect behavior. Students warned that the recent shooting would be suspended after the retry using the selected function when needed for phase detection of unnecessary or excessive exercise pistol. Combined with real-time biofeedback applications, it can lead to accelerated learning, training the number of shots that poverty can be reduced, thereby saving time and costs.     

室温离子液体在气体和湿度传感器中的应用

室温离子液体由于其蒸气压低、离子导电性高、热稳定性好和电化学窗口宽等优良的物理化学特性而得到了广泛的重视,该文简略综述了近年来室温离子液体在气体和湿度传感器中应用的相关研究.