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基于北斗导航系统实现列车定位具有显著的性能及成本效益.为确保其符合特定应用需求,需要对定位完好性进行有效监测.立足于对常规接收机自主完好性监测方法进行有效辅助,本文提出一种应用于北斗列车定位的接收机自主完好性监测可用性预测方法.该方法利用北斗导航系统历书信息,结合列车运行计划实施完好性监测离线计算,预先对实际行车过程中可能的完好性状况进行估计,为列车在途定位完好性监测计算提供先验信息,确保定位结果满足应用需求.采用现场试验数据验证了本文所提出方法的预测能力,在基于卫星导航的列车控制等系统领域具有重要的应用价值.     

A multiobjective model for maximizing fleet availability under the presence of flight and maintenance requirements

Every aircraft, military or civilian, must be grounded for maintenance after it has completed a certain number of flight hours since its last maintenance check. In this paper, we address the problem of deciding which available aircraft should fly and for how long, and which grounded aircraft should perform maintenance operations, in a group of aircraft that comprise a combat unit. The objective is to achieve maximum availability of the unit over the planning horizon. We develop a multiobjective optimization model for this problem, and we illustrate its application and solution on a real life instance drawn from the Hellenic Air Force. We also propose two heuristic approaches for solving large scale instances of the problem. We conclude with a discussion that gives insight into the behavior of the model and of the heuristics, based on the analysis of the results obtained.     

牵引模式对C0-C0架悬式机车粘着性能的影响

分析了牵引模式对C0-C0架悬式机车粘着性能的影响.通过对牵引装置不同布置方式进行比较,指出机车的轴重转移量以车体中央截面成对称分布,对应轮对上的粘着质量利用率之和为定值;并提出牵引点高度对机车粘着性能影响较大,而牵引装置布置方式对其影响较小,机车设计时需根据悬挂特性选择合适的牵引点高度.     

城市轨道交通系统可靠性指标及其计算

基于系统可靠性概念,构建了城市轨道交通系统的可靠性指标体系,提出了运营可靠度、运营恢复度及运营利用率等指标的定义,给出了相应的计算方法。应用该方法计算了上海轨道交通1、2、3号线的可靠性指标。     

Elasticities for taxicab fares and service availability

This study utilizes a unique dataset from New York City to examine the effects of taxi fare increases on trip demand and the availability of taxi service. The elasticity of trip demand with respect to fares is estimated to be –0.22; the elasticity of service availability with respect to the taxi fare is 0.28; and the elasticity of service availability with respect to total supply of service is near 1.0. These results have important implications for taxi regulatory decisions. First, fare increases do substantially increase industry revenues but at a lesser rate than the percentage increase in the fare. The implication for policy-makers is that fare elasticities must be carefully considered to obtain desired improvements in drivers' earnings. Second, service availability -- an important aspect of service quality that is generally overlooked during fare policy debates -- should be a central consideration in fare setting, given the considerable impact of fares on availability. Finally, where the supply of cabs needs to be expanded, the number of cabs can be significantly increased without harming the revenue stream of existing operators. This finding alleviates a major industry objection to issuing additional taxicab licenses.     

基于贝叶斯网络考虑共因失效的高速铁路牵引变电所可靠性分析

运用一种基于故障树的贝叶斯网络分析法,相比于传统的故障树分析法,它能够灵活地表示不确定信息,并能进行不确定性推理。并提出牵引变电所的寿命分布为指数分布,建立牵引变电所电气主接线的贝叶斯网络模型,对于系统二态性特征以及系统可靠度也符合指数分布,故在牵引变电所中选取β因子模型作为共因失效模型,显式分析方法作为共因失效的分析方法。用MATLAB对考虑共因失效的贝叶斯网络进行编程,并绘制相应的可靠度以及瞬时可用度的曲线图,结果表明在考虑共因失效后系统的可靠度有所降低,意味着得出的结果更接近实际。此外,实现牵引变电所定性和定量的评估,计算其可靠性指标,确定系统的薄弱环节。     

并网型风电机组可靠性设计

介绍了并网型风电机组可靠性指标及其评估方法,及并网型风电机组的运行情况;根据并网型风电机组可靠性串联模型,对并网型风电机组进行可靠性设计,找出其薄弱环节,提高其可靠性,达到提高可利用率和年发电量的目的。     

使用可用度在舰船装备论证中的约束作用

在舰船装备论证过程中,使用可用度不仅是装备保障能力的量化,还对装备的一些因素有着约束作用。分析使用可用度在论证过程中对装备数量、维修计划、随船备件满足率和全寿命周期费用的影响,建立这些参数之间的定性关系表达式,发现提高舰船使用可用度,有助于减少舰船装备数量和降低装备寿命周期费用,但也会缩短装备寿命期内的维修时间,并要求装备有较高的备件满足率。     

典型任务剖面内舰船机电单部件系统备件配置方法研究

根据舰船机电设备在典型任务剖面内的航渡、作战和撤离返航三个阶段不同故障特点,建立了任务周期内新的备件配置模型:航渡和撤离返航两个阶段利用以可用度为中心的Monte-Carlo仿真方法进行备件配置;作战阶段根据战损情况进行备件配置;系统总的备件配置数量等于三个阶段备件配置数量的和.计算实例表明,文中提出的备件配置方法能更准确地反映舰船系统备件的实际需求.     

舰艇柴油发电机组系统稳态可用度分析磁

柴油发电机组系统是船舶动力系统的重要组成部分,为船舶设备正常工作提供用电保障。作为船舶独立电源,其性能稳定性和工作可靠性是设计、使用部门最为关注的问题。船舶一般配置4～8台柴油发电机组,通过控制柜,构成比较复杂的供电电网。论文针对船舶柴油发电机组及供电网络的特点,运用马尔科夫模型,对系统可用度进行计算、分析,找出提高机组系统可用度的措施,为柴油发电机组系统设计、使用提供参考。