矿用隔爆兼本安型计算机信号隔离器设计

针对煤矿井下电气设备要求本质安全的特点,设计了一种矿用隔爆兼本安型计算机信号隔离器,主要介绍了该隔离器的硬件电路设计。该隔离器主要用于矿井中本质安全型计算机主机与外部输入输出设备的连接,能够实时地传送键盘输入的数据,具有良好的信号隔离功能和抗干扰性能。     

矿用隔爆兼本质安全型不间断直流稳压电源的设计

基于本质安全型电源的原理及特点,提出了一种矿用隔爆兼本质安全型不间断直流稳压电源的设计方案,详细介绍了该电源主要电路的设计。该电源采用LM317可调稳压芯片实现稳压功能,具有使用方便、电路简单、变换效率高、成本低等优点。测试结果表明,该电源达到了本安标准,满足了安全型电气设备的需求。     

煤矿井下采掘设备隔爆兼本安型电气控制箱的本安设计

针对煤矿井下采掘设备防爆兼本安型电气控制箱内本安电路与非本安电路并存、非本安电路的能量可能会窜入本安电路而影响本安电路防爆及本安性能的问题,从结构设计和电气隔离两方面介绍了煤矿井下采掘设备隔爆兼本安型电气控制箱的本安设计方法,给出了电气间隙、爬电距离、绝缘及耐压、接线端子、本安布线、电源变压器、本安隔离栅印制板等结构布置方法以及RS485通信隔离电路、模拟量隔离电路、压频变换电路、电阻信号隔离电路、开关量隔离电路、继电器隔离电路等电气隔离措施。应用表明,采用该方法设计的煤矿井下采掘设备隔爆兼本安型电气控制箱安全可靠,维护简便,能够满足煤矿井下的防爆要求。     

基于神经网络观测器的飞控传感器在线故障诊断

为提高无人机飞行安全可靠性,针对飞行控制系统中常出现的传感器故障以及非线性气动力模型参数难以确定的问题,提出了基于BP神经网络观测器估计的故障诊断方法;引用LM改进算法对网络参数进行调整,构造了神经网络观测器模型逼近非线性系统,并运用于飞行控制系统进行在线数字仿真,对垂直陀螺输出卡死故障、恒偏差故障和恒增益故障分别进行仿真分析;仿真结果表明,所设计神经网络观测器可以有效估计系统输出,在线诊断传感器故障。     

Analysis of information exchange activities to actualize and validate situation awareness during shift changeovers in nuclear power plants

Shift work situations occur in almost all safety‐critical organizations, and the investigations of some catastrophes like Chernobyl, Exxon Valdez, and the Gol/Legacy mid‐air collision indicated that shift work information exchange played an important role during the evolution of the situation before the accidents. Inadequate communications during shift changeovers challenged operators' work in the moments that preceded these accidents, because they got inadequate information about the current situation. Our research focuses on the information exchange activities (verbal, written, and nonverbal) of nuclear power plant control operators during shift changeovers. Our aim is to investigate how verbal exchanges and other representations enable operator crews to share information regarding the events that occurred in the previous shift to achieve adequate situation awareness. Our findings indicated the importance and richness of the information exchange during the shift changeover process to update and validate individual and collective situation awareness, showing that information adequately shared enables the ad hoc configurations of regulation loops and a safer use of simplified strategies that can be understood and be validated by other operators, reducing the occurrence of cognitive overloads and contributing to the construction of a common cognitive ground that enhances system resilience. © 2010 Wiley Periodicals, Inc.     

Transparency in complex dynamic food supply chains

Food supply chains are increasingly complex and dynamic due to (i) increasing product proliferation to serve ever diversifying and globalising markets as a form of mass customisation with resulting global flows of raw materials, ingredients and products, and (ii) the need to satisfy changing and variable consumer and governmental demands with respect to food safety, animal welfare, and environmental impact. Transparency in the food supply chain is essential to guarantee food quality and provenance to all users of food and food products. Intensified information exchange and integrated information systems involving all chain actors are needed to achieve transparency with respect to a multitude of food properties.In this paper, specific challenges of food supply chains are highlighted. Major elements are addressed that support transparency to consumers, the government and food companies, which are considered the claimants of transparency. Elements considered to be enablers of transparency are governance mechanisms, quality and safety standards and information exchange. The paper specifies these transparency claimants and enablers for food supply chains and identifies major information system functions and information technology applications needed to comply with transparency demands. It thereby provides a framework for transparency analysis in food supply chains.     

关于加强计算机网络安全管理的思考

计算机网络的使用在当今社会已经达到普及的程度,随之而来的计算机网络安全问题正受到越来越多人的关注。本文从计算机网络安全的定义及网络安全问题出现的原因分析入手,结合技术和管理两个层面,谈谈如何加强计算机网络安全管理。以供参考。     

Simulation of smoke flow and longitudinal ventilation in tunnel fire

1 Introduction The tunnel is one of the important facilities of railroad and highway transportation, and also a throat of railroad and highway. With the development of transportation, there are more and more tunnels. Although the tunnel fire occurs seldo…     

小型储气罐火灾工况数值模拟分析

以某输气管线气液联动执行机构中的储气罐为例,利用Ansys Fluent软件建立同比例三维模型,模拟火灾工况下,外部热量不断输入,罐内压力和罐体温度随时间的变化情况。利用Aspen Hysys软件模拟计算该小型储气罐在火灾工况下安全泄放所需的最小安全阀口径。结果表明,当钢制储气罐外部发生火灾时,罐体温度和罐内压力急剧升高,在很短的时间内就能达到储气罐坍塌温度和储气罐设计压力;达到钢制储气罐坍塌温度的时间滞后于达到储气罐设计压力的时间;从安全的角度,设置安全阀可安全有效泄放气体,即使储气罐发生坍塌,也有助于降低事故发生的危害程度;确定的安全阀最小口径为0.03 cm²,建议选型的安全阀口径不低于0.05 cm²。     

基于行为安全2-4模型的大众滑雪事故行为原因分析

运用文献资料、数理统计等方法,以行为安全2-4模型分析53例大众滑雪事故的行为原因,并构建模型。结果：滑雪者未能保持安全距离、滑雪场工作人员未尽到安全保障义务,是引发滑雪事故发生最多的一次性不安全行为;滑雪场防护网是引发事故频次最高的不安全物态;滑雪者未保持安全距离是事故发生最多的习惯性行为。滑雪场安全管理体系欠缺主要表现在滑雪场员工安全操作规程欠缺。