一种基于失效检测器的快速异步系统共识算法*

异步系统下的共识问题是容错方向中的关键问题。首先分析了几种基于失效检测器的共识算法,然后考虑减少响应时间,对现有算法提出改进。改进后的算法满足异步系统下共识问题的两阶段最低限度,并且在特定条件下可以在第一阶段快速作出响应。经实验证明,改进后的算法具有更快的响应时间和较少的通信量。     

软件缺陷分类的研究

软件缺陷分类是研究软件缺陷管理的基础。说明了软件缺陷的危害,阐述了对软件缺陷分类的必要性,考察了国内外关于软件缺陷错误分类的各种方法,分析了各种分类法的优缺点,提出了一个有利于提高软件质量和改进软件过程的分类方法,指出了缺陷管理系统的基本功能要求并总结了对软件缺陷进行分类的意义。     

Optimal acceptance sampling plans for log-location-scale lifetime models using average risks

Assuming that the probability of obtaining a defective unit in a production process, p, is not constant, a versatile methodology is presented for determining optimal failure-censored reliability sampling plans for log-location-scale lifetime models. The optimization procedure to decide the acceptability of a product is usually sufficiently accurate for the most widely used parametric lifetime models, such as the Weibull and lognormal distributions, and fairly robust to small deviations in the prior knowledge. Moreover, lower and upper bounds on the optimal sample size, and the corresponding acceptance constants, are derived in closed-forms. The proposed approach extends the traditional sampling plans to those cases in which appreciable prior information on p exists, and also allows the analyst the flexibility to delimitate the range of p and to incorporate into the reliability analysis prior impartiality between the producer and the consumer. In addition, the practitioners may achieve substantial savings in sample size, better information on the production process and better assessment of the true producer and consumer risks. An example related to the acceptability of a certain kind of gyroscope is included for illustrative purposes. Various practical prior distributions are considered to describe the random fluctuations in the proportion defective.     

嵌入式气象灾报子系统在电网GIS系统中开发与应用

将气象灾报系统作为电网GIS系统的嵌入式子系统,与电网在GIS中的模型和拓扑结构、SCADA系统实时数据相切合,做好灾害发生前的预判和灾后故障查找,最大限度降低灾害带来的大面积停电及设备损毁的损失.     

An assessment of neck and upper extremity disorders by questionnaire and clinical examination

Abstract

To study the usefulness of a screening questionnaire for neck/upper extremity complaints, 165 women in either repetitive industrial, or mobile and varied work, were studied by the questionnaire and by a detailed clinical physical examination. A total of 94 subjects recorded complaintsin the questionnaire. In 140 subjects findingswere recorded at the examination. Most subjects with findings at the clinical examination of shoulders reported complaints in the questionnaire (sensitivity 80%). For the other anatomical regions, the sensitivity was rather low (42– 65%). For all regions, most subjects without findings reported no complaints (specificity 77–97%). A total of 75 subjects were given clinical diagnoses according to a set of predetermined diagnostic criteria. The capacity of the questionnaire to identify diagnoses of shoulders was higher (sensitivity 92%) than for the other regions (66–79%). Of subjects who did not qualify for diagnosis, a majority (specificity 71–81%) did not report complaints in the questionnaire. We conclude that the questionnaire approach gives a fairly good picture of the neck/upper extremity status of a working female population. However, a clear view of the size of a problem is obtained only by a detailed clinical examination, particularly as regards the neck, elbows and hands, for which the questionnaire gave an underestimate.     

Mechanical properties and failure characteristics of fractured sandstone with grouting and anchorage简

Based on uniaxial compression experimental results on fractured sandstone with grouting and anchorage, we studied the strength and deformation properties, the failure model, crack formation and evolution laws of fractured sandstone under different conditions of anchorage. The experimental results show that the strength and elastic modulus of fractured sandstone with different fracture angles are significantly lower than those of intact sandstone. Compared with the fractured samples without anchorage, the peak strength, residual strength, peak and ultimate axial strain of fractured sandstone under different anchorage increase by 64.5–320.0%, 62.8–493.0%, and 31.6–181.4%, respectively. The number of bolts and degree of pre-stress has certain effects on the peak strength and failure model of fractured sandstone. The peak strength of fractured sandstone under different anchorage increases to some extent, and the failure model of fractured sandstone also transforms from tensile failure to tensile–shear mixed failure with the number of bolts. The pre-stress can restrain the formation and evolution process of tensile cracks, delay the failure process of fractured sandstone under anchorage and impel the transformation of failure model from brittle failure to plastic failure.     

城市轨道交通电力监控系统的不足与未来展望

随着轨道交通的快速发展、运能负荷运日增长,电力设备故障也明显增加,网络化运营逐渐形成的趋势下,传统的电力监控系统采集精度低、综合监控程度不高,无法实现监控、预警及抢修处理的一体化,对于网络化运营的实现具有一定的局限性.展望未来的电力监控系统,可实现高精度的实时电力监控,达到及时发现预警,精确定位故障的目的,具备有效的应急方案,实现网络化安全运营.系统可采集高精度电流、电压、相位数据,通过专业算法对实时监控数据的计算和对比,产生预警信号;通过故障定位算法精确确定故障位置,生成故障事件,进行处理,全程监控事件处理过程,可实现实时建议指导;并且配备预案库及知识库,提供历史经验参考,快速有效的解决电力故障,恢复列车运营,实现高度集中的、可靠的网络化安全运营.     

利用S700K道岔动作电流曲线迅速判断表示电路故障

对S700K提速道岔动作电流曲线进行分析,结合提速道岔动作电路原理,迅速判断处理表示电路室内外故障。     

Multiaxial fatigue and failure analysis of helical compression springs

Multiaxial fatigue criteria are applied to the analysis of helical compression springs. The critical plane approaches, Fatemi–Socie and Wang–Brown, and the Coffin–Manson method based on shear deformation, were used to predict fatigue lives of the springs under constant amplitude loading. Experimental fatigue lives are compared with the multiaxial fatigue criteria predictions. The stress analysis was carried out in the finite element code ANSYS, and the multiaxial fatigue study was performed using the fatigue software nCode. A failure analysis was conducted in order to determine the fatigue crack initiation point and a comparison of that location with the most damaged zone predicted by the numerical analysis is made. The Fatemi–Socie critical plane approach gives a good prediction of fatigue life. While the Wang–Brown criterion overestimates spring fatigue life, the Coffin–Mason model gives conservative results.     

Light composite elliptic springs for vehicle suspension

For composites to compete in vehicle suspension applications, it is essential to control their failure by utilising their strength in principal direction instead of shear. This can be achieved efficiently by employing a new configuration instead of existing one. This study marries between an elliptical configuration and the woven roving composites.

In this paper, the influence of ellipticity ratio on performance of woven roving wrapped composite elliptical springs has been investigated both experimentally and numerically. A series of experiments was conducted for composite elliptical springs with ellipticity ratios (a/b) ranging from one to two. Typical failure histories of their failure mechanism are presented and discussed. In general, this study demonstrated that composites elliptical spring can be used for light and heavy trucks and meet the requirements, together with substantial weight saving. The results showed that the ellipticity ratio significantly influenced the spring rate and failure loads. Composite elliptic spring with ellipticity ratios of a/b 2.0 displayed the highest spring rate.