Empirical formulas and global reliability evaluation of reliability graphs

Some formulas have been reported, in terms of elements and nodes, to calculate the number of reliability graphs of identical elements in series-parallel configurations. A simple and efficient algorithm has been proposed for enumeration of spanning trees using an incidence matrix which is used for global reliability evaluation of a graph. An example demonstrates the effectiveness of the algorithm.     

Prolog representation of reliability networks and evaluation of system reliability

The suitabilities of Prolog to represent reliability networks are discussed in this paper. The capabilities of Prolog are illustrated by relevant examples in various reliability network configurations. The network reliability has been estimated by using the recursive nature of Prolog.     

Sequential evaluation of terminal pair reliability in a reliability network

For a non-series-parallel reliability network, the terminal pair reliability is evaluated sequentially and the model is extended to consider the possibility of improving the reliability of a link by a parallel duplication.     

一种评估软件可靠性的方法

首先介绍了模糊综合评判法的概念,接着论述了模糊综合评判法的评估方法和步骤,并简单介绍了综合评判的四种模型,最后运用模糊评估方法评估了某通信网综合网络管理系统的软件系统的可靠性。     

OBDD-based evaluation of k-terminal network reliability

An efficient approach to determining the reliability of an undirected k-terminal network based on 2-terminal reliability functions is presented. First, a feasible set of (k-1) terminal-pairs is chosen, and the 2-terminal reliability functions of the (k-1) terminal-pairs are generated based on the edge expansion diagram using an OBDD (ordered binary decision diagram). Then the k-terminal reliability function can be efficiently constructed by combining these (k-1) reliability expressions with the Boolean and operation. Because building 2-terminal reliability functions and reducing redundant computations by merging reliability functions can be done very efficiently, the proposed approaches are much faster than those which directly expand the entire network or directly factor the k-terminal networks. The effectiveness of this approach is demonstrated by performing experiments on several large benchmark networks. An example of appreciable improvement is that the evaluation of the reliability of a source-terminal 3/spl times/10 all-terminal network took only 2.4 seconds on a SPARC 20 workstation. This is much faster than previous factoring-algorithms.     

通信网可靠性综合评估

影响通信网的可靠性因素很多。在考虑多个测度指标的情况下,通信网可靠性评估是多指标的综合评价,提出了三种综合评估方法。其中基于神经网络的综合评判较好地解决了综合评价指标中各指标的权数确定又尽可能地排除了人为因素的影响这一难题。     

Fuzzy logic based network reliability evaluation

A method for evaluation of the reliability of a network and its nodes is suggested reflecting the customers' requirements and needs stated in linguistic form. The method uses the fuzzy logic to formulate criteria for reliability evaluation and grading on a percentage scale. An illustrative example is included.     

Enhanced reliability evaluation for self-checking circuits

A first attempt at evaluating the reliability of the checkers used in self-checking circuits is presented. Simple theory is proposed to compare different checker implementations that, although totally self-checking in the conventional sense, may perform differently under more realistic fault conditions. As a significant example of application, the case of the 1-out-of-3 checker is explicitly treated     

Composite generation/transmission reliability evaluation

Surveys some of the methodologies and computational techniques used for composite generation/transmission reliability evaluation. Topics addressed include: a conceptual framework for reliability evaluation, characterization of system states, selection of a system state, assessment of the selected state, estimation of reliability indices, sensitivity analysis, and techniques for reducing computational effort. The approaches are illustrated in case studies with utility-derived systems     

直升机机载电子设备可靠性综合评估

通过引入由分系统的可靠性参数综合评估系统可靠性参数的理论模型，对直升机机载电子设备的可靠性进行了综合评估，并通过计算举例进行验证，说明运用这种理论模型对直升机机载电子设备可靠性进行评估的可行性。     

Efficient reliability evaluation methodologies for combinational circuits

Reliability evaluation methodologies have become important in circuit design. In this paper, we focus on the probabilistic transfer matrix (PTM), which has proven to be a gate-level approach for accurately assess the reliability of a combinational circuit with penalty in simulation runtime and memory usage. In order to improve its efficiency, several methodologies based on traditional PTM are proposed. A general tool is developed to calculate the reliability of a circuit with efficient computation methods based on an optimized PTM (denoted as ECPTM), which achieves runtime and memory usage improvement. Experiments demonstrate how the proposed simulation framework, combined with traditional PTM method, can provide significant reduction in computation runtime and memory usage with different benchmark circuits.     

Comprehensive gate-oxide reliability evaluation for dram processes

This paper discusses dielectric breakdown as a major cause for failure of ICs with less than a half-micron linewidth. Focusing on DRAMs the characterization of dielectric reliability using different types of properly designed test structures and appropriate stress methods is reviewed. Considerations concerning screens and upper limits for stress conditions are presented. With a step stress, the sample size can be reduced and efficiently used to cover the specified lifetime. To understand and identify relevant failure mechanisms, physical failure analysis of representative fails is required.     

Bounds evaluation of coefficients in the reliability polynomial

In this study a class of new methods to evaluate bounds of the reliability polynomial coefficients is proposed. These new methods enumerate progressively simple paths or p-acyclic subgraphs finding for each new term a closer lower bound. The process, for high complex networks, can be interrupted, obtaining in this case only approximate values, while the final exact results can be obtained for computationally tractable networks. Alternatively, the a priori knowledge of all simple paths allows us to find a succession of upper and lower bounds still convergent to the exact values of coefficients. Finally, a comparison is done between the results obtained in this paper and those already presented in the literature.     

Signal probability for reliability evaluation of logic circuits

As integrated circuits scale down into nanometer dimensions, a great reduction on the reliability of combinational blocks is expected. This way, the susceptibility of circuits to intermittent and transient faults is becoming a key parameter in the evaluation of logic circuits, and fast and accurate ways of reliability analysis must be developed. This paper presents a reliability analysis methodology based on signal probability, which is of straightforward application and can be easily integrated in the design flow. The proposed methodology computes circuit’s signal reliability as a function of its logical masking capabilities, concerning multiple simultaneous faults occurrence.     

The graphical reliability evaluation of three-state device networks

A device is said to have three states if it has one successful and two failure modes (i.e., opened and shorted or closed). A typical example of such devices is an electronic diode, an electric switch, a relay, a fluid flow valve, etc.The networks made up of such devices present a complication in the reliability analysis as the networks become more complex.This paper presents a newly developed graphical technique to analyse any type of simple or complex three-state device network with much simplicity, straightforwardness and limited reliability theory knowledge. The theory behind this newly developed technique is briefly explained and the rules to use this technique are established. Some numerical examples are presented and compared with the results obtained from the conventional method. The graphical and conventional results compare quite favourably.     

Application of expert systems to systems reliability evaluation

An expert system for diagnosing rough ride problems in heavy trucks has been developed and can be used on a personal computer. The system operates on two levels of knowledge data base: shallow — acquired from truck service personnel and causal obtained from a multiprobe vibration analysis system (MVAS) through a preprocessing neural network. The justification for selecting neural networks is presented as are virtues and drawbacks of the developed system.     

Modification of cutsets for reliability evaluation of communication systems

A general and simple technique for the evaluation of symbolic reliability expression in the case of practical systems such as a communication system having fixed channel capacities of its various communicating links, a computer communication network allowing a fixed amount of data exchange amongst different terminals of various computer centres and a power distribution system having limited power ratings of its various power lines, is presented. A system is considered reliable only if it successfully transmits at least the required system capacity from the transmitter to the receiver station. In this method, the various branch sets are obtained which completely disrupt the communication path, i.e. ensure system failure. It is observed that these branch sets are not necessarily the cutsets in the usual graph theoretic sense. The unreliability expression is then determined by adopting an existing method for making various terms disjoint. Two typical examples are solved by this method. It is observed that the method is computationally fast and efficient.     

A hierarchical reliability analysis for circuit design evaluation

We suggest a computationally efficient and flexible strategy for assessment of reliability of integrated circuits. The concept of hierarchical reliability analysis proposed relies on doing reliability assessments during the design and layout process [reliability computer aided design (RCAD)]. Design rules are suggested based on calculations of steady-state mechanical stresses built up in interconnect graphs and trees due to electromigration. These design rules identify a large fraction of interconnect graphs in a typical design as immune to electromigration-induced failure. The stated design rules are an extension of the Blech-length concept to interconnect graphs. Our suggested new strategy will have important implications for design and layout processes as design limits for a given technology are reached     

Electromigration reliability evaluation for a three-level metallization process

The electromigration behaviour of triple level Al-1%Si-0.5%Cu thin films is presented as used in a metallization process necessary for high-density CMOS (HDCMOS) ASIC technology. A prediction time-to-failure (TTF_x) formula has been fit and the 0.01% cumulative-failure-function F(t) vs. time has been calculated. Reliability improvement was achieved by using test vehicles baked for t=1400 hrs at T=200°C.Maximum current density design rules are derived as a function of the sigma value for each metal level.     

A recursive method for network reliability measures evaluation

A new recursive method for evaluation of reliability measure of the communication networks is given in this paper. The main idea of this method is based on the generation of aggregated networks related to the partitions on subsets of node set. Having found the probabilities of the networks states composing the aggregated network, reliability measures can be obtained by summing up the suitable probabilities of the aggregated networks.