Software reliability growth with test coverage

"Software test-coverage measures" quantify the degree of thoroughness of testing. Tools are now available that measure test-coverage in terms of blocks, branches, computation-uses, predicate-uses, etc. that are covered. This paper models the relations among testing time, coverage, and reliability. An LE (logarithmic-exponential) model is presented that relates testing effort to test coverage (block, branch, computation-use, or predicate-use). The model is based on the hypothesis that the enumerable elements (like branches or blocks) for any coverage measure have various probabilities of being exercised; just like defects have various probabilities of being encountered. This model allows relating a test-coverage measure directly with defect-coverage. The model is fitted to 4 data-sets for programs with real defects. In the model, defect coverage can predict the time to next failure. The LE model can eliminate variables like test-application strategy from consideration. It is suitable for high reliability applications where automatic (or manual) test generation is used to cover enumerables which have not yet been tested. The data-sets used suggest the potential of the proposed model. The model is simple and easily explained, and thus can be suitable for industrial use. The LE model is based on the time-based logarithmic software-reliability growth model. It considers that: at 100% coverage for a given enumerable, all defects might not yet have been found.     

Enhancing reliability with thermal transient testing

Thermal transient measurement, the method for the characterisation of IC packages is gaining increasing importance. The measurement of these transients requires dedicated equipment. The paper discusses the methodology of thermal transient measurements in details, including the compensation of second order effects as non-linearity, non-constant powering etc. In the following part the evaluation methods and algorithmic solutions are discussed. A typical example is presented. Reliability issues are discussed in the last section of the paper, including the problem of die attach testing. The contribution of the thermal transient measurements to the analysis of thermo-mechanical strain is demonstrated.     

Software reliability measurement

The measurement and analysis aspects of software reliability are described with the aim of providing software engineers and managers a sense of where and how software reliability measurements can be applied to their projects. Some background for understanding software reliability measurement is provided, and activities associated with measuring and analyzing software reliability are discussed in the context of the software product life cycle. The focus is on failures and the rate at which they occur. The thrust of reliability measurement and analysis is to specify what the customer needs in terms of reliability before a software product is built, to validate that these needs are met before delivery of the product to the customer, and to make sure that the customer's needs continue to be met after delivery     

Software reliability growth model with error dependency

Generally, in a complex software system there may be errors, whose removal is dependent on the previously removed errors and may result in a slowing down of the removal process for a period time. This dependency can be described in different ways. In this paper, we develop an SRGM which takes care of the underlying error dependency in a software system. The SRGM has the built-in flexibility and has been tested on real software error data to show its applicability.     

Software testing

There are several types of software testing that are widely used in the current IT world. This paper explain some of these types of tests and describes the author's experiences with them. When a tester knows what type of testing is needed, it greatly improves the test results and ultimately decreases the number of defects. Test methods covered include glass box testing, black box testing, system testing, database testing, and security testing, and test team selection is also discussed     

Software reliability of programs with network structure

The aim of this paper is to present the reliability expression of programs/packages with general network structure, which is not sequential, branch or parallel in logic flow of the concerned algorithm. The reliability expression for logic flow (R_L) of an example program of a general network structure (whose segments are listed in Appendix 1) is discussed and thereby overall reliability expression for the entire program which can be built in several different ways is derived. Such evaluations help increase the probability of programs having complex structure to be executed without errors on the computer system. The problem is obviously of great interest to programmers/system analysts while designing the flow system, debugging or testing the program.     

Software reliability how it affects system reliability

This paper suggests that there is an additional measurable attribute, system “structuredness” which contributes to system reliability. It examines the effect of the structure of software on the integrity of a system. It shows how intuition fails us, when we accept a less hierarchally structured system and expect it to behave as reliably. “Structuredness”, can be used together with the system availability figure to provide a realistic measure of system integrity. The results of implementing structured programming techniques to increase software reliability are briefly discussed.     

Software reliability - bibliography

This paper presents a brief introduction and extensive list of selective bibliography on software reliability and related areas.     

Software reliability growth supermodels

The aim of this paper is to present a method for obtaining a more accurate prediction for software reliability growth models (SRGMs). It is our belief that if we try to use a more general approach implying the building of a supermodel as a weighted sum of several SRGMs, it may be possible to obtain more accurate results in prediction. The weight factors will depend on the values of the prequential likelihood functions as calculated for each SRGM, the values varying each time a new error is observed. The basic models chosen are the Jelinski-Moranda, Goel-Okumoto, Duane, Littlewood-Verrall and Keiller-Littlewood models. Finally, we shall compare the SRGMs with the supermodels by using the median estimate and deciding if there are any benefits or constraints in applying this technique.     

软件开发预估工作量的适当参数选定

软件开发工作量估算在系统开发中为组织决策和项目管理相关的任务提供有效的支持.不同的估算技术各有自己的优点和局限性,没有一种估算技术能适用于所有开发环境,并且软件开发方法和技术的更新速度也对所有这些估算技术提出了挑战.这里以重回归分析方法为例探讨如何选用适当参数,以提高估算准确性.     

基于改进Elman网络模型的软件可靠性预测

为提高神经网络模型对软件可靠性预测结果的准确性和可信性,提出了一种基于多目标优化算法改进Elman网络模型Mop-IElman(multi-objective optimization-based improved Elman neural network)的方法:1)在Elman网络基础上,设计输出层的延迟反馈层,作为另一个状态层;2)以网络的结构和2个状态层的初始输出值为网络配置的变量,以网络的预测精度和顽健性为目标,采用NSGA-II(non-dominated sorting genetic algorithm II)进行多目标优化得到帕累托解,最大化网络预测精度与顽健性之和从而确定网络配置。通过两组实际软件失效数据对Mop-IElman进行实验验证,并与前馈网络、Elman网络、单目标优化Elman网络以及多目标优化Elman网络进行比较研究,结果表明Mop-IElman的预测结果具有较高的准确性和可信性。     

Optimum software release policy with random life cycle

A software release problem based on four software reliability growth models (SRGMs) with random life-cycle length is studied. Test of the software system is terminated after time T and released (sold) to the user at a price. The price of the software system and three cost components are considered, and average total profit is used as a criterion. The optimal values of release times are shown to be finite and unique. Hence, the optimal solutions can be obtained numerically by, for example, a bisection method. A numerical example indicates that the optimal release time increases as (1) the error rate in each model decreases and (2) the difference between the error fixing cost during the test phase and that during the operational phase increases. The case of unknown model parameters is considered only for the Jelinski-Moranda model because a Bayes model is not available for other SRGMs. The release decision depends on testing time, but other stopping rules, for example based on the number of corrected errors, can be considered     

数字电视 可靠性试验设计

可靠性技术是提高产品质量的有效手段,具有广阔的应用前景。结合国内外可靠性试验技术对数字电视可靠性设计进行分析,分别介绍了可靠性的主要特征量、可靠性试验论证设计、贝叶斯验证试验、可靠性试验方案设计等方面,供相关实验室及检测人员参考。     

Bayes stopping rules for reliability testing with the exponentialdistribution

These rules for terminating testing involve achieving specified levels of credibility in both: (1) the probability of the posterior estimate of the exponential scale-parameter, &thetas;, after some, m, of the units have been tested, and (2) the mean of the probability of &thetas; over the remaining units, when viewed pessimistically. Sample decision tables and a numerical example illustrate both the sequential and batch testing cases. Large savings in test times can be achieved whenever the first m units present strong evidence in favor of either hypothesis (H₀: &thetas;=&thetas;₀ vs. H₁ : &thetas;=&thetas;₁, &thetas;₁<&thetas; ₀)     

Software reliability estimations for telecommunications products

Reliability of software used in telecommunications networks is a crucial determinant of network performance. Software reliability (SR) estimation is an important element of a network product's reliability management. In particular, SR estimation can guide the product's system testing process and releasability decisions. SR estimation is performed using an appropriate SR estimation model. However, the art of SR estimation is still evolving. There are many available SR estimation models to select from, with different models being appropriate for different applications. Although there is no “ultimate” and “universal” SR model on the horizon (and there may not be one in the foreseeable future), methods have been developed for selecting a trustworthy SR model for each application. The present authors have been analyzing and adapting these methods for applicability to network software. Their results indicate that there already exist methods for SR model selection which are practical to use for telecommunications software. If utilized, these methods can promote significant improvements in SR management. The paper presents the results to date     

Software reliability models: A review

In this paper we review several software reliability models and provide an extensive listing of papers dealing with software reliability modelling and their applications. The models discussed are grouped into two broad categories: empirical and analytical models. Analytical models are further subdivided into static and dynamic models, and the general theory behind these models are reviewed. Based on the observations made in this review, we provide suggestions for future research.     

An efficient reliability testing method combined with thermal performance monitoring

Die attach delamination in power electronic devices is a common failure mode besides bond wire damage. This paper describes the chip and packaging level effects of a newly developed power cycling test on novel mid-power automotive MOSFETs. The introduced method was pilot tested with our new approach, using a recently developed test environment. The idea was to combine the existent guidelines of the most relevant semiconductor characterization and cycling standards while saving time and resources during testing. Thermal transient measurements during the actively mimicked temperature cycling reliability test were evaluated along with K-factor calibration to identify different failure modes. This approach allows distinguishing between electrical and thermal related structural failure modes. The major target was to test the reliability of a new thermal interface material which was used in the MOSFETs under test. We found that the new material was able to withstand the 150 °C temperature amplitude beyond 100,000 cycles without critical failures. The changes of the thermal performance of the complete assembly were tracked from the pre-stress state until a sample reached critical condition.