Irregular Time‐Varying Stress Degradation Path Modeling: a Case Study on Lithium‐ion Cell Degradation

The aim of this paper is to investigate the issue of degradation modeling and reliability assessment for products under irregular time‐varying stresses. Conventional degradation models have been extensively used in the relevant literature to characterize degradation processes under deterministic stresses. However, the time‐varying stress, which may affect degradation processes, widely exists in field conditions. This paper extends the general degradation‐path model by considering the effects of time‐varying stresses. The new degradation‐path model captures influences of varying stresses on performance characteristics. A nonlinear least square method is used to estimate the unknown parameters of the proposed model. A bootstrap algorithm is adopted for computing the confidence intervals of the mean time to failure and percentiles of the failure‐time distribution. Finally, a case study of lithium‐ion cells is presented to validate the proposed method. Copyright © 2015 John Wiley & Sons, Ltd.     

应用移动Marple法拟合动态测试数据的时变AR模型

本文利用较实用的时变自回归（ＡＲ）模型，来拟合动态测试（尤其是长过程测试）中的二阶非平衡数据，并且不采用当前广泛使用的递推算法，而探讨应用移动Ｍａｒｐｌｅ算法来拟合该时变模型。经各种类型数据的仿真试验及某些实例的计算结果表明，该方法具有与常用递推算法同样的时变跟踪能力，而无明显的滞后现象，且拟合精确度较高、稳定性好，只是计算速度略低。可见对于非平稳数据不便应用成批算法的观点，需作重新认识。     

An Approach for Reliability Demonstration Test Based on Power‐Law Growth Model

Reliability demonstration test (RDT) is a critical and necessary step before the acceptance of an industrial system. Generally, a RDT focuses on designing a test plan through which one can judge whether the system reliability indices meet specific requirements. There are many established RDT plans, but few have incorporated the reliability growth aspects of the corresponding products. In this paper, we examine a comprehensive test plan that involves information concerning the reliability growth stage. An approach for RDT under the assumption of the power‐law model is proposed. It combines data related to the growth stage with those pertaining to the test stage of the product to reduce the cost of the test. Through simulation studies and numerical examples, we illustrate the characteristics of the test plan and significant reduction in test costs through our approach. Copyright © 2017 John Wiley & Sons, Ltd.     

Reliability Assessment of High Voltage Direct Current Grid Protection Schemes

Recent renewable energy developments in the power system have prompted a growing interest in high voltage direct current (DC) grids. One of the challenges impeding the progress of high voltage DC grids is the design of DC protection systems. This paper presents the development of an energy reliability program which differentiates between the energy reliability performances of five different DC protection schemes. The energy reliability program utilized contingency enumeration to iterate through all network states of the high voltage DC grid. The conditions used by the program for network state differentiation were formulated from minimal cut‐sets. The energy reliability analysis results discussed in this study illustrate that the double‐bus single breaker protection scheme has the most favourable performance. These results contribute knowledge to the design of DC protection schemes of high voltage DC grids. Copyright © 2014 John Wiley & Sons, Ltd.     

就地化保护装置跌落冲击载荷下的可靠性分析

目的 为了评估就地化保护装置跌落冲击载荷下的失效情况。方法 基于显式动力学理论,采用有限元法对就地化保护装置进行跌落冲击的建模仿真。分析PCB板变形与焊点失效之间的关系,探讨元件封装方式对产品抗跌落冲击性能的影响,提出以Von Mises准则得到的焊点最大应力联合跌落寿命模型,进行元件封装可靠性评估的分析方法。针对元件不同封装方式的装置进行跌落验证试验。结果 就地化保护装置跌落冲击仿真结果与试验结果基本吻合。结论 验证了评估元件封装失效分析方法的准确性,为推断产品可靠性提供了理论支撑。     

System Travel Time Reliability: A Measure of the Quality of Service of Networks

In this study, the travel time reliability of network systems is measured by travel time limitation as well as two‐terminal reliability. In the network, each arc is a binary random variable weighted by travel time as well as by operational probability. The performance index or QoS of a network system indicates the probability that the source node can successfully travel to the destination node, while satisfying the travel time limitation. Unlike existing literature that evaluated travel time reliability via a single optimization path, the proposed index focuses on the performance of the entire network system. This study presents an efficient decomposition method in computing QoS based on the Dijkstra shortest path method. We employ a small network to demonstrate the algorithm step by step. In addition, computational experiments conducted on a prototype network show that the proposed algorithm is superior to existing methods. Copyright © 2015 John Wiley & Sons, Ltd.     

利用可靠性模型确定电子测量设备检定周期的方法

周期检定是保障计量器具能够准确可靠地开展测量活动的重要手段.检定周期的长度影响计量器具测量活动的可靠性和计量工作的经济性.本文通过建立电子测量设备测量可靠性与使用时间关系的数学模型提出了利用可靠性模型确定电子测量设备检定周期的可靠性评估法.该方法可以有效地保证电子测量设备检定周期制定的科学性.     

Total System Reliability: Integrated Model for Growth and Test Termination

Reliability demonstration testing is not the most efficient method of assuring product reliability prior to shipment. It is costly, time consuming and has inherent technical and social limitations. The dilemma facing the reliability and quality engineer is whether to continue demonstration testing and risk shipping a product late or ship the product and risk warranty and field service returns. Either option can cause the company to lose significant market share and profit. This paper sets out to solve this dilemma by meeting both the time to market constraints and the product reliability goals. The weaknesses of existing reliability demonstration techniques are explored and a comprehensive methodology is introduced involving controlled development processes, stress testing, root cause determination and process change feedback mechanisms. All prototype products are manufactured on the final volume process line resulting in the early identification and correction of process‐related problems. Testing commences on the first available prototypes with system stress/robust testing being employed to stimulate failures, determine their root cause and correct them. Reliability growth modelling assesses the ongoing improvements occurring in reliability during the development cycle, while a statistical stopping rule is used to determine the optimal product release time without risking product warranty. The approach is applicable to systems incorporating both hardware and software elements. The methodology has been validated on three development projects of telecommunication systems comprising hardware and software. In addition to enhancing team behaviour and performance, the development times have been reduced by 14% and the ramp‐up time to full worldwide product shipments has been reduced by 50%. Copyright © 2005 John Wiley & Sons, Ltd.     

Calibration of Voltage Transformers and High- Voltage Capacitors at NIST

The National Institute of Standards and Technology (NIST) calibration service for voltage transformers and high-voltage capacitors is described. The service for voltage transformers provides measurements of ratio correction factors and phase angles at primary voltages up to 170 kV and secondary voltages as low as 10 V at 60 Hz. Calibrations at frequencies from 50–400 Hz are available over a more limited voltage range. The service for high-voltage capacitors provides measurements of capacitance and dissipation factor at applied voltages ranging from 100 V to 170 kV at 60 Hz depending on the nominal capacitance. Calibrations over a reduced voltage range at other frequencies are also available. As in the case with voltage transformers, these voltage constraints are determined by the facilities at NIST.     

System Reliability with Multiple Failure Modes and Time Scales

Lifetime of some systems can be measured based on multiple time scales. For instance, the lifetime of an airplane may be affected by its mileage or number of landings. Furthermore, most systems are exposed to competing risks. In this regard, time scales can accelerate the failure mechanism of these systems. In this paper, the behavior of systems is investigated under competing risks and multiple time scales. The time scales follow independent Poisson processes. As it is not straight forward obtaining closed‐form relations for the system reliability, we have provided a parametric upper bound. Also, the upper bound can be tightened by considering an error function. The error function can be built by regression on a sample containing real values of system reliability for given time units. Performance of the upper bound is studied in two numerical examples and a case study. Results show that the obtained upper bound is very tight. Copyright © 2015 John Wiley & Sons, Ltd.     

Reliability Optimization by Considering Time‐Dependent Reliability for Components

Reliability optimization is an important and challenging topic both in engineering and industrial situations as its objective is to design a highly reliable system that operates more safely and efficiently under constraints. Redundancy allocation problem (RAP), as one of the most well‐known problems in reliability optimization, has been the subject of many studies over the past few decades. RAP aims to find the best structure and the optimal redundancy level for each subsystem. The main goal in RAP is to maximize the overall system reliability considering some constraints. In all the previous RAP studies, the reliability of the components is considered constant during the system's mission time. However, reliability is time‐dependent and needs to be considered and monitored during the system's lifetime. In this paper, the reliability of components is considered as a function of time, and the RAP is reformulated by introducing a new criterion called ‘mission design life’ defined as the integration of the system reliability function during the mission time. We propose an efficient algorithm for this problem and demonstrate its performance using two examples. Furthermore, we demonstrate the importance of the new approach using a benchmark problem in RAP. Copyright © 2017 John Wiley & Sons, Ltd.     

基于聚类分析和时间浓缩的空调可靠性评估

应用售后故障数据评估可靠性的关键在于科学地确定研究子样.通过对中国气候区域的聚类分析、故障判据的界定以及空调使用时间浓缩,解决了用户空调工作状况及所处自然环境各异,空调功能季节性规律工作以及具体工作时间无法记录而导致使用时间与实际工作时间存在转换比的问题,获得了分组多重截尾售后故障数据子样.运用指数分布模型的极大似然估计和工作时间不确切的可靠性评估理论对比验证了使用时间压缩的合理性.对某型挂壁式定频空调分析结果表明,所提出的评估方法能够有效应用于空调可靠性水平的评估,对类似产品应用售后故障数据开展可靠性评估也具有很好的参考价值.     

Reliability challenges for low voltage/low power integrated circuits

This review paper discusses reliability considerations for low voltage/low power integrated circuit technologies. This growing market will continue to be dominated by scaled CMOS, with silicon on insulator technology growing in importance due to improved performance and reliability over bulk, low power CMOS. Power dissipation, performance, and reliability will be traded off at all levels of system design; this paper concentrates on device level issues. An aggressive low voltage/low power technology development path could yield a CMOS/SOI technology with 40 nm junctions, 5 nm gate oxides, and 0·9 V supplies. Such an aggressive low voltage/low power technology alters many traditional reliability problems such as metallization failure, oxide breakdown, hot carrier effects, electrostatic discharge, leakage currents, soft errors and analogue circuit noise. SOI brings additional reliability concerns such as heat dissipation through the buried oxide, bipolar latch, and back interface effects. This paper examines several of these issues and identifies a number of present and future reliability challenges for low voltage/low power technology.     

飞机电网直流电压畸变信号测试方法

随着飞机上非线性负载的增加,它们对电网的影响越来越引起人们的重视。本文采用模拟滤波和数字信号处理技术,完成了对飞机电气系统直流电压畸变的测试,给出了对某型飞机电网的实际测试结果。     

变压器可靠性指标评定技术的研究

电力变压器是由铁芯、绕组、油箱、器身绝缘、冷却装置、保护装置、引线装置等零部件所组成的一个系统,影响其功能和寿命的因素很多很复杂,其中包括影响其固有可靠度的主要因素与影响其使用可靠度的因素。对变压器进行可靠性分析,首先必须获得一定数量的与变压器工作寿命有关的信息。本文的工作主要包括对在实际环境下运行的一定数量的变压器的工作情况进行调查,收集有关失效情况、寿命数据等信息,从中分析、处理有用的数据,从而来分析现有变压器的可靠度,并为变压器可靠性技术指标制定及评定做一些必要的基础工作。     

Performance Enhancement of Electronic and Energy Devices via Block Copolymer Self‐Assembly

The use of self‐assembled block copolymers (BCPs) for the fabrication of electronic and energy devices has received a tremendous amount of attention as a non‐traditional approach to patterning integrated circuit elements at nanometer dimensions and densities inaccessible to traditional lithography techniques. The exquisite control over the dimensional features of the self‐assembled nanostructures (i.e., shape, size, and periodicity) is one of the most attractive properties of BCP self‐assembly. Harmonic spatial arrangement of the self‐assembled nanoelements at desired positions on the chip may offer a new strategy for the fabrication of electronic and energy devices. Several recent reports show the great promise in using BCP self‐assembly for practical applications of electronic and energy devices, leading to substantial enhancements of the device performance. Recent progress is summarized here, with regard to the performance enhancements of non‐volatile memory, electrical sensor, and energy devices enabled by directed BCP self‐assembly.     

Clustering Empirical Failure Rate Curves for Reliability Prediction Purposes in the Case of Consumer Electronic Products

In this paper, a methodology based on the combination of time series modeling and soft computational methods is presented to model and forecast bathtub‐shaped failure rate data of newly marketed consumer electronics. The time‐dependent functions of historical failure rates are typified by parameters of an analytic model that grabs the most important characteristics of these curves. The proposed approach is also verified by the presentation of an industrial application brought along at an electrical repair service provider company. The prediction capability of the introduced methodology is compared with moving average‐based and exponential smoothing‐based forecasting methods. According to the results of comparison, the presented method can be considered as a viable alternative reliability prediction technique. Copyright © 2015 John Wiley & Sons, Ltd.     

Real‐time Reliability Evaluation with a General Wiener Process‐based Degradation Model

The aim of this paper is to investigate the issue of real‐time reliability evaluation based on a general Wiener process‐based degradation model. With its mathematical tractability, the Wiener process with a linear drift has been widely used in the literature, to characterize the dynamics of the degradation process or its transformation. However, the nonlinear degradation process, which can't be properly linearized, exists in practice. The dynamics of such a degradation process can't be accurately captured by linear models. Here, a general Wiener process‐based degradation model is proposed, which covers a variety of Wiener process‐based models as its limiting cases. A two‐stage method is presented to estimate the unknown parameters. Two real‐time reliability evaluation procedures are presented for different conditions: one is the analytical evaluation procedure, and the other is the simulated evaluation procedure. It is shown that when new degradation information is available, the evaluation results can be adaptively updated. Moreover, to check out the proposed degradation model, a graphical method is provided. Finally, the validity of the proposed evaluation method is illustrated by a numerical example and two real‐world examples. Copyright © 2013 John Wiley & Sons, Ltd.     

A Spacecraft Launch Organizational Reliability Model Based on CSF

Organizational reliability, with regard to safety, needs to be assessed for the launch of spacecraft. In this paper, the compensatory and irreplaceable factor is defined while the organizational reliability of a spacecraft launch is researched by studying the decomposition and composition of factors. The factors of space and the characteristics of the organizational reliability of a spacecraft launch are analyzed. The composition method for the states of compensatory and irreplaceable factors is then established, and the overall organizational reliability model of spacecraft launch is constructed. This paper also uses the grey relational analysis technique to analyze and construct a model to assess the organizational maturity of important factors affecting organizational reliability. Finally, a case analysis demonstrates the application of the organizational reliability assessment model of a spacecraft launch, which validates the feasibility and effectiveness of the composition of states of factors. Copyright © 2012 John Wiley & Sons, Ltd.