Modeling repair events under intermittent failures and failures subject to unsuccessful repair

Intermittent failures are sometimes observed for a repairable system, such as an automobile. Such failures often lead to a series of unsuccessful repair attempts before the source of the failure has been identified and removed. Unsuccessful repair is also observed in cases where the failures are not intermittent. In order to model data involving repeated repair attempts related to the same failure, repair times cannot usually be assumed negligible and the model must be designed or modified to account for these. In this paper, we propose a modified version of the branching Poisson process model introduced by Lewis (1964). We discuss statistical inference procedures for this model and demonstrate these procedures using the service history of a new automobile. Copyright © 2002 John Wiley & Sons, Ltd.     

间歇循环制气中泵出口压力调节系统的改进

在间歇循环制气中，通过对生产参数的正确计算，选用合适的气动薄膜控制阀，构成PID自动调节系统，达到稳定泵出口压力的目标。     

Control of filamentous organisms in food‐processing wastewater treatment by intermittent aeration and selectors

Various measures were tested at a full‐scale wastewater treatment plant to control sludge bulking by type 0041 and 0675 filamentous microorganisms, instigated by highly variable wastewater loadings from a food‐processing facility. Intermittent aeration on a 1‐h on 1‐h off basis was found to effect a marginal improvement in sludge settling characteristics, as reflected by about an 11–36% reduction in the Sludge Volume Index (SVI) to 118 cm^?3 g^?1. At BOD loadings of 1500 kg d^?1 which marginally exceeded the design capacity of the plant of 1200 kg d^?1, SVI rose sharply to 230 cm^?3 g^?1 in less than a week. The anoxic selector effected a reduction in SVI to 170 cm^?3 g^?1 within 3 weeks of operation at temperatures of 8–12 °C. The aerobic selector was most effective, reducing SVIs further to 79 cm^?3 g^?1 in 2 weeks. Sludge settleablity was found to be inversely proportional to the aerobic selector food‐to‐microorganism ratio. The optimum aerobic selector loading was found to be 1.8–2.7 kgBOD₅ kgMLVSS d^?1, with corresponding SVIs in the range of 80–120 cm^?3 g^?1. © 2003 Society of Chemical Industry     

Precise Determination of Power-Off Time of Intermittent Supply Technology Based on Fuzzy Control for Energy Saving of Beam Pumping Motor Systems

Beam pumping motors undergo heavy and light loads as well as motor and generator modes during a running cycle. The intermittent supply control technology can achieve significant energy saving in such a motor system. However, due to the vibration of the mechanical transmission link and the dynamic liquid level in oil wells, it is difficult to determine the power-off time precisely. This paper proposes a power-off time determination method based on fuzzy control strategy. The method first determines the operation parameters, such as the load changing rates and the durations of motor and generator modes. Then the optimal scheme of intermittent supply control is selected according to the identified parameters. Finally, the fuzzy controller is established with the speed variation after the power-off set as the input, and the cumulative power value set as the output. The power-off time is corrected by comparing the output variable with the cumulative power value obtained by real-time identification. In addition, the controller can automatically track the dynamic load by correcting the identification results of input power curve. The energy saving device is developed and applied to oilfields. The tests show that the energy saving ratio reaches 15% without reducing oil yields.     

Criteria for intermittent and continuous disturbance transitiion of ERA interaction with

There are two interaction mechanisms between shaped charge jet and the thin flying plate driven by explosion, that is, the intermittent and continuous disturbance. Determination of the transition criteria for the intermittent and continuous disturbance is of importance for the penetration calculation of the escaping jet and the design of ERA. In this paper a new criteria is presented based on the analysis of interaction process, and the effects of NATO angle and the thickness of flying plate on the disturbance frequency are discussed. It is shown that the critical shaped charge jet velocity increases with the plate thickness and NATO angle, especially increases drastically between 450 and 600.     

气压连续过滤机

叙述了气压连续过滤机的结构和工作原理。气压连续过滤机综合了板框或厢式压滤机过滤压强大和真空过滤机连续作业的优点，它拥有产率高、滤饼水分低和能源消耗小的特性，它的开发能使我国步入世界过滤领域的先进行列。     

基于单片机的间隙老化控制器的设计

文章所提出的间隙老化控制器采用AT 89S52单片机做为主控制器,可进行产品老化的控制和老化状态的显示,文章介绍了了该设计的软、硬件设计方案,并从测试结果上验证了老化试验的效果     

刀具破损机理国内外研究概况及发展趋势

介绍了刀具破损机理研究的主要领域,包括断续切削过程中的切入切出破损研究、热应力和热裂纹与破损之间关系、刀具几何参数影响以及破损监控预报研究等,回顾了刀具破损机理研究的历史和现状,对切入切出破损、动态切削力及热应力和热裂纹与破损之间关系的研究概况进行了详细论述,最后论述了刀具破损研究的发展趋势。     

基于555定时器的三相异步电动机电子控制设计

555定时器输出的高低电平可以控制继电器的吸合与断开.而继电器的吸合与断开又可以用来控制电机的运行,这样555定时器作为控制电路核心器件就实现了对电动机的自动控制.本文讲述了555定时器对电动机作间歇运转控制、定时控制以及三相异步电动机的Y-△换接起动的自动控制.     

夏热冬冷地区居住建筑体形系数对建筑能耗影响的分析

控制体形系数是基于采暖空调设备连续运行时减少外表面换热面积。而夏热冬冷地区的居住建筑采暖空调设备绝大多数为间歇性运行,采暖空调房间的传热面由外内围护结构共同构成,外围护结构对房间采暖空调负荷影响显著下降。以南京地区一组建筑为例,使用动态模拟软件DeST-h,研究在采暖空调间歇运行模式下,居住建筑体形系数与全年采暖空调能耗的关系,分析表明,在采暖空调间歇运行模式下,居住建筑能耗与体形系数并没有必然的对应关系,不必对居住建筑体形系数严格限制,可以适当放宽要求。