Software Reliability models for the first stage of Software Projects

A software reliability analysis for the first stage of software projects is presented. At this very first stage of testing we expect an increasing failure rate, where the usual software reliability growth models based on non homogeneous Poisson processes like the Goel-Okumoto or Musa-Okumoto can not be applied. However, our analysis involves some models that combine reliability growth with increasing failure rates like the logistic and delayed S-shaped models. Our analysis also includes a new model based on contagion as in the increasing failure rate as in the reliability growth stages. We point out that increasing failure rate stages are important to be modeled since corrective actions can be taken soon and also that this characteristics highlights under modern development methodologies which development is performed simultaneously as testing, like in Agile and TDD (Test driven development). Results of the application of those models to real datasets is shown.Sociedad Argentina de Informática e Investigación Operativ

Software Reliability models for the first stage of Software Projects

A software reliability analysis for the first stage of software projects is presented. At this very first stage of testing we expect an increasing failure rate, where the usual software reliability growth models based on non homogeneous Poisson processes like the Goel-Okumoto or Musa-Okumoto can not be applied. However, our analysis involves some models that combine reliability growth with increasing failure rates like the logistic and delayed S-shaped models. Our analysis also includes a new model based on contagion as in the increasing failure rate as in the reliability growth stages. We point out that increasing failure rate stages are important to be modeled since corrective actions can be taken soon and also that this characteristics highlights under modern development methodologies which development is performed simultaneously as testing, like in Agile and TDD (Test driven development). Results of the application of those models to real datasets is shown.Sociedad Argentina de Informática e Investigación Operativ

A global survey on the current state of practice in Zero Defect Manufacturing and its impact on production performance

To be competitive in dynamic and global markets, manufacturing companies are continuously seeking to apply innovative production strategies and methods combined with advanced digital technologies to improve their flexibility, productivity, quality, environmental impact, and cost performance. Zero Defect Manufacturing is a disruptive concept providing production strategies and methods with underlying advanced digital technologies to fill the gap. While scientific knowledge within this area has increased exponentially, the current practices and impact of Zero Defect Manufacturing on companies over time are still unknown. Therefore, this survey aims to map the current state of practice in Zero Defect Manufacturing and identify its impact on production performance. The results show that although Zero Defect Manufacturing strategies and methods are widely applied and can have a strong positive impact on production performance, this has not always been the case. The findings also indicate that digital technologies are increasingly used, however, the potential of artificial intelligence and extended reality is still less exploited. We contribute to theory by detailing the research needs of Zero Defect Manufacturing from the practitioner’s perspective and suggesting actions to enhance Zero Defect Manufacturing strategies and methods. Further, we provide practical and managerial suggestions to improve production performances and move towards sustainable development and zero waste.publishedVersio

Search based software engineering: Trends, techniques and applications

© ACM, 2012. This is the author's version of the work. It is posted here by permission of ACM for your personal use. Not for redistribution. The definitive version is available from the link below.In the past five years there has been a dramatic increase in work on Search-Based Software Engineering (SBSE), an approach to Software Engineering (SE) in which Search-Based Optimization (SBO) algorithms are used to address problems in SE. SBSE has been applied to problems throughout the SE lifecycle, from requirements and project planning to maintenance and reengineering. The approach is attractive because it offers a suite of adaptive automated and semiautomated solutions in situations typified by large complex problem spaces with multiple competing and conflicting objectives. This article provides a review and classification of literature on SBSE. The work identifies research trends and relationships between the techniques applied and the applications to which they have been applied and highlights gaps in the literature and avenues for further research.EPSRC and E

Research and technology highlights of the Lewis Research Center

Highlights of research accomplishments of the Lewis Research Center for fiscal year 1984 are presented. The report is divided into four major sections covering aeronautics, space communications, space technology, and materials and structures. Six articles on energy are included in the space technology section

Improved method of searching the associative rules while developing the software

As the delivery of the good quality software in time is very important part of the software development process, it's very important task to organize this process very accurately. For this a new method of the searching associative rules where proposed. It is based on the classification of the all tasks on three different groups, depending on their difficulty, and after this, searching associative rules among them, which will help to define the time necessary to perform specific task by specific develope

Industry/University Collaboration at the University of Michigan-Dearborn: A Focus on Relevant Technology

https://deepblue.lib.umich.edu/bitstream/2027.42/154106/1/kampfner1998.pd

Cost-Sensitive Radial Basis Function Neural Network Classifier for Software Defect Prediction

Effective prediction of software modules, those that are prone to defects, will enable software developers to achieve efficient allocation of resources and to concentrate on quality assurance activities. The process of software development life cycle basically includes design, analysis, implementation, testing, and release phases. Generally, software testing is a critical task in the software development process wherein it is to save time and budget by detecting defects at the earliest and deliver a product without defects to the customers. This testing phase should be carefully operated in an effective manner to release a defect-free (bug-free) software product to the customers. In order to improve the software testing process, fault prediction methods identify the software parts that are more noted to be defect-prone. This paper proposes a prediction approach based on conventional radial basis function neural network (RBFNN) and the novel adaptive dimensional biogeography based optimization (ADBBO) model. The developed ADBBO based RBFNN model is tested with five publicly available datasets from the NASA data program repository. The computed results prove the effectiveness of the proposed ADBBO-RBFNN classifier approach with respect to the considered metrics in comparison with that of the early predictors available in the literature for the same datasets

Testing and Modelling of SLM manufactured Ti-6Al-4V alloy under low cycle fatigue and creep conditions

Selective laser melting (SLM) is a promising additive manufacturing (AM) process for high strength or high manufacturing costs metals such as Ti-6Al-4V widely applied in aeronautical industry components with high material waste or complex geometry. However, the disadvantage or challenge of AM is the unpredictable fatigue and creep properties of AM components. To realize the wide application of structural components manufactured by AM technology, their creep/fatigue failure and damage mechanism need to be understood so that the life of AM components can be predicted reliably. In this thesis, tensile and fracture mechanics type specimens were machined in accordance with the relevant ASTM standards from fabricated SLM with different heat treatment methods. All the specimens were post-treated with the same machined smooth surface and heated to relieve the residual stress. Various mechanical tests of the standard samples were performed to obtain the properties aiming to identify the critical factors influencing these properties. The room temperature tests carried out in this work include the tensile test, low cycle fatigue (LCF) test, crack growth rate investigation, and fracture toughness test. The LCF test was conducted using the standard samples in the low cycle fatigue (LCF) regime. The failure mechanism is observed by identifying the influence of post-processing methods. Scanning electron microscopy (SEM) techniques and optical microscopy (OM) are used to investigate the microstructural and fracture surface features of different types of specimens. In addition, a microstructure-based multistage fatigue model was applied to predict the LCF lives, which shows good agreement with the experimental results. Crack growth rate and fracture toughness tests were carried out and analyzed on the CT samples. Different build orientations and heat treatment methods effects on the fracture toughness and FCG rate were observed. A novel approach is presented to show a relationship between the FCG rate and microstructure characteristic using the database for the FCG tests and their microstructure and fractography analysis established from the experiments carried out. It was found that HIP treatment can help to reduce the effects of building directions due to the elimination of anisotropy. Furthermore, when the crack growth direction is perpendicular to the manufacturing direction, the crack growth rate is sensitive to the heat treatment method. The high-temperature properties test was largely focused on constant load uniaxial and notched bar creep tests under a continuous temperature environment. The uniaxial creep test of four types of SLM manufactured samples was carried out under 600℃ conditions at two stress levels. The notch acuity sensitivity investigation was conducted using the double sharp and blunt notched bar at 90 MPa, 600℃ and 100 MPa, 500℃, respectively. It is observed that no obvious defects were found in the fracture surface and crack profile. By comparing and analyzing the creep test results, the HIP-treated sample have a prior creep failure duration time to all the other manufacturing parameters. This demonstrates that the slightly elongated microstructure samples can help to improve the creep resistance by the characterization investigation. From the notched bar experimental results, the sharp notched bars have longer creep time and less strain deformation in the whole creep test process. The creep cracking behavior at the specific proper temperature was investigated and verified. A continuum damage mechanics-based model was proposed using a custom user subroutine in FE analysis software Abaqus to simulate the creep cracking damage evolution behaviors. The model applied a grain and grain boundary scale in meshing the creep cracking region using a CT geometry the same as that for the creep cracking test. The high temperature and mechanical properties were obtained from the test in this project. Considering that the defects were not detected in the fracture surface or crack profile, the FE model was operated without any distribution of voids. The microstructural features like average grain size and shape were described and generated in terms of meshing elements. The simulation results were found to be conservative and are validated by comparing them with the fracture behavior and crack propagation of the CT samples. The present work shows that in future work on creep testing and modeling of the additively manufactured material, looking at the effects of voids and interstitials in the microstructure, the damage simulation can be developed to more accurately describe creep under both uniaxial and multiaxial conditions.Open Acces