基于证据推理规则的无线传感器网络数据可靠性分析

无线传感器网络(Wireless Sensor Network,WSN)在精密工程中具有广泛的应用,对数据精度的要求严苛,因此对WSN可靠性进行评估具有实用价值。本文以WSN实际监测数据为研究对象,通过对WSN数据提取特征,选取所测环境数据的时间相关性和空间相关性以及节点电压为可靠性指标,提出了基于证据推理规则(Evidential reasoning rule,ER)的WSN数据可靠性评估模型。该模型采用变异系数法和基于距离的方法,确定评估指标权重和可靠度,以基于规则的方法将指标数据统一成置信分布形式,利用证据推理规则对指标和参数进行融合,得到WSN数据可靠性状态。最后,通过实例分析验证该模型的有效性。

中国实验快堆可靠性数据分析评估技术研究

本文以中国实验快堆(CEFR)为研究对象,研究得出了适用于中国实验快堆的经典的可靠性数据分析方法 ,同时,由于CEFR在役时间短及设备的特殊性所导致难以通过经典统计得到准确的分布参数的限制,提出了CEFR可靠性数据可引用的通用数据源和以概率统计、贝叶斯估计为主的可靠性数据分析方法。采用基于网络的软件技术,开发完成了快堆设备可靠性数据分析评估软件。并应用该软件以中国实验快堆主循环钠泵为对象进行可靠性数据的分析评估研究。

基于对称加密和双层真值发现的连续群智感知激励机制

针对连续群智感知中隐私要求提高、收集到的感知数据不可靠和用户参与感知任务积极性低等问题,提出了一种基于对称加密和双层真值发现的连续群智感知激励机制(Symmetric Encryption and Double Truth Discovery Based Incentive Mechanism,SDIM)。首先,使用对称加密算法对感知数据进行隐私保护,在隐私要求较高并且感知数据量较大时,可以降低计算开销,减少数据加密和奖励计算的时间。其次,基于双层真值发现模型提出了一种支持数据可靠性评估的激励机制,实现连续群智感知的实时奖励,并在参与者有恶意行为时提高奖励公平性。最后给出了SDIM的双重隐私性分析。仿真结果表明,SDIM可以根据数据可靠性有效地计算出真值和奖励,在数据加密和奖励分发的时间上明显优于对比模型,并在参与者有恶意行为时能够更加公平地计算奖励。

Product reliability assessment based on proportional hazard degradation model

In order to evaluate the reliability of long-lifetime products with degradation data, a new proportional hazard degradation model is proposed. By the similarity between time-degradation data and stress-accelerated lifetime, and the failure rate function of degradation data which is assumed to be proportional to the time covariate, the reliability assessment based on a proportional hazard degradation model is realized. The least squares method is used to estimate the model＇s parameters. Based on the failure rate of the degradation data and the proportion function of the known time, the failure rate and the reliability function under the given time and the predetermined failure threshold can be extrapolated. A long life GaAs laser is selected as a case study and its reliability is evaluated. The results show that the proposed method can accurately describe the degradation process and it is effective for the reliability assessment of long lifetime products.

System reliability assessment based on Wiener process and competing failure analysis

Considering the dependence and competitive relation-ship between traumatic failure and degradation,the reliability assessment of products based on competing failure analysis is studied.The hazard rate of traumatic failure is regarded as a Weibull distribution of the degradation performance,and the Wiener process is used to describe the degradation process.The parameters are estimated with the maximum likelihood estimation（MLE）method.A reliability model based on competing failure analysis is proposed.A case study of the GaAs lasers is given to validate the effectiveness of the model and its solving method.The results indicate that if only the degradation failure is considered,the estimated result will be comparably optimistic.Meanwhile,the correlation between the degradation and traumatic failure has a great influence on the accuracy of reliability assessment.

Reliability evaluation for Weibull distribution under multiply type-? censoring

The multiply type-I censoring represented that all units in life test were terminated at different times. For estimations of Weibull parameters, it was easy to compute the maximum likelihood estimation （MLE） and least-squares estimation （LSE） while it was hard to build confidence intervals （CI）. The concept of generalized confidence interval （GCI） was introduced to build CIs of parameters under multiply type-I censoring. Further, GCI based on LSE and GCI based on MLE were proposed. It is mathematically proved that the former is exact and the latter is approximate. Besides, a Monte Carlo simulation study and an illustrative example also Ran out that the GCI method based on LSE yields rather satisfactory results by comparison with the ones based on MLE. It should be clear that the GCI method is a sensible choice to evaluate reliability under multiply type-I censoring.

The Challenges of Assessing the Output of EmergentEconomies： The Case of Bahrain

Business analysts worldwide use the standard theories and tools of macroeconomics and finance to determine the investment, trade or production possibilities in foreign markets. These evaluations are generally supported by three sources： estimations of using country-specific macroeconomic data on which they can determine patterns of growth, inflation, unemployment, productivity, income per capita, etc.; timely data on current conditions and developments in production, income and spending; and institutional information on policy makers, business practices and financial markets. This paper focuses on the first two where we examine the publically available macroeconomic data for the Kingdom of Bahrain to determine their reliability. Among our findings are： （1） creating a reliable data base of macroeconomic data is difficult due to data revision and incomplete data gathering; （2） the movement of standard macro-variables is often unusual, leading one to question further the reliability of the data; （3） based on available data it appears that the growth in Bahrain has been driven almost solely by an increase in the number of people working, with little to no apparent rise in productivity; and （4） the growth of GDP will eventually be constrained by physical limits on population growth, and can be improved only if ways can be found to increase the productivity of the workforce.