International Journal of Reliability and Safety (8 papers in press)

Regular Issues

• Reliability analysis using change-point concept and optimal version-updating for open source software  
  by Ajay Kumar 
  Abstract: Our main objective is to analyse the reliability of open source software (OSS) using a change-point concept and estimate the optimal time for version updating of OSS. The focus is to provide an efficient parametric decomposition that will result in an analytical expression for the mean value function for predicting the OSS reliability that could be used by the software developer as well as software user to judge the reliability of OSS. A reliability growth model for OSS has been proposed on the basis of a modified NHPP which is developed by incorporating the change-point concept and imperfect debugging with constant Fault Reduction Factor (FRF). Owing to the varying nature of bugs and frequent software releases in OSS, the fault detection process cannot be smooth. To overcome the non-smoothness in the fault detection process, the change point concept has been incorporated in the model to assess OSS reliability. Such a reliability growth model further can be applied to estimate optimal time for version updating of OSS by considering the two important factors in the context, involvement of the volunteers and newcomers and reliability to ensure the quality of the software using multi-attribute utility theory. The proposed model has been tested on datasets from the public release of Apache open-source software and it has been found that the proposed model provides more accurate reliability estimation. Moreover, the proposed reliability growth model for OSS helps management to determine the optimal version-updating time for OSS using multi-attribute utility theory. The proposed model is practically implicated since it considers the multiple releases of the software to be common by taking the reliability growth model for each release individually into consideration. Furthermore, multiple change points can be considered in order to make the model more accurate.
  Keywords: open source software; fault reduction factor; change-point; imperfect debugging; software reliability growth model; multi-attribute utility theory; non-homogeneous Poisson process.
  
  
• Code-based CRUD analysis for prioritising test cases  
  by Tomohiro Takeda, Satoshi Masuda, Tohru Matsuodani, Tsuyoshi Yumoto, Kazuhiko Tsuda 
  Abstract: When software is modified, an impact analysis is conducted to determine the effect of these modifications on other functions. However, the current impact-analysis techniques cannot identify such impact analysis. To compensate for this, comprehensive test cases are created. Therefore, impact analysis faces problems when increasing the true-positive ratio, which denotes the impacted implementations, and when reducing the false-positive ratio, which denotes the non-impacted implementations. To address this, Impact-Data-All-Used (IDAU) can be used to create and prioritise test cases based on CRUD information contained in design documents. We herein propose a code-based-IDAU (CB-IDAU) that applies IDAU to the source code using the control-graph and call-graph analysis. Based on a performance comparison of CB-IDAU to that of its previously proposed version, CB-IDAU, we observed an increase in the true-positive value by 157% and a reduction in the false-positive value by 60% when the full-coverage-test performance was used as the benchmark.
  Keywords: software testing; impact analysis; test case creation; call flow; control flow; data flow; testing automation; test case prioritisation; graph search; intermediate language.
  
  
• Estimation for the mixture of flexible Weibull extension and Burr XII distributions under adaptive type-II progressive censoring scheme  
  by Rania M. Kamal, Moshira A. Ismail 
  Abstract: In this paper, based on an adaptive type-II progressive censoring scheme, estimation of the mixture of Burr XII and flexible Weibull extension distribution is discussed. Maximum likelihood estimation and asymptotic confidence intervals of the unknown parameters of the distribution are established. Using the Adaptive Metropolis (AM) method, we also carry out Bayesian estimation of the unknown parameters of the distribution under symmetric and asymmetric loss functions. To evaluate the performance of the estimates, a simulation study is carried out. Finally, a numerical example using a real data set is analysed to illustrate the proposed estimation methods.
  Keywords: mixture distribution; censoring; maximum likelihood estimation; Bayesian estimation; adaptive metropolis.
  
  
• MCDM approach for reliable and effective maintenance of farm machinery in the context of agricultural sectors in India  
  by Debesh Mishra, Suchismita Satapathy 
  Abstract: The maintenance of agricultural machinery is critical for their correct operation as well as the seamless operation of farm activities. This study used a questionnaire survey to assess farmers' knowledge of farm-related machinery maintenance operations in Odisha (India), and found that the greatest number of farmers, 131 (90.35%), were shown to require additional instruction and assistance in the successful maintenance of mechanised reapers. In addition, a thorough literature research was conducted, followed by expert consultation, to identify farm machinery maintenance activities (MMAs) for self-propelled reapers. The Step-wise Weight Assessment Ratio Analysis (SWARA) method was used to rank the MMAs for reapers based on their prioritization, and the ranking revealed that, based on the prioritising of a reaper's MMAs criterion, Inspection of clutchs working ranked first; followed by Inspection of cutters working; Inspection of conveying-chain; Inspection of grain-lifters working; and Inspection of placing-angle. Correspondingly, the associated ranking based on the prioritising of all sub-criteria under the concerned criterion for MMAs was obtained. The outcomes of this study can assist decision-makers, operators, and agricultural producers in maintaining improved working conditions for farm-operated mechanised reapers.
  Keywords: farm machinery; reapers; self-propelled reapers; farm machinery maintenance activities; MMAs; SWARA; MCDM; India.
  
  
• Developing a civil aviation safety management maturity model to promote the safety level of civil aviation  
  by Fuqiang Qi, Ziruo Jia 
  Abstract: Through a literature review of safety maturity model and safety management research, it is sorely needed and feasible to develop a safety management maturity model for Civil Aviation. The Civil Aviation Safety Management Maturity Model (CASM3) with five levels of maturity and consisting of four domains, 12 assessment items and 33 assessment indicators were developed. The five levels of maturity with varying characteristics were defined, and the assessment criteria were developed considering the assessment indicators from the view of plan-do-check-act management theory. The quantitative-qualitative maturity assessment method for assessing the maturity level of safety management was adopted, and the reliability and objectively of assessment are ensured by weighting each assessment index. Once the level of safety management maturity is determined by using CASM3, the action plans are apparent, which will improve the weak sectors towards the criterion of next or higher maturity level to improve the integral maturity level. The CASM3 provide a ladder for organisations to improve their safety management maturities step by step, which makes the continuous improvement of the capability of safety management from qualified level to excellent level as a journey.
  Keywords: civil aviation; safety management capacity; safety management maturity model; safety management assessment; safety plan and organisation; safety management process; safety management guarantee; safety management supervision.
  
  
• A comparison study for bearing remaining useful life prediction by using standard stochastic approach and digital twin  
  by Jie Liu, Jørn Vatn, Viggo Gabriel Borg Pedersen, Shen Yin, Bahareh Tajiani 
  Abstract: Remaining useful life prediction is important for research of maintenance. It is common to use stochastic approaches to predict remaining useful life of components. On the other hand, there is a digital twin model developed by MATLAB for bearings real-time remaining useful life prediction. To have a better understanding of the advantages and disadvantages of these models, an experiment was designed and implemented to get real degradation data of bearings for model testing. Two stochastic approaches are selected which are Wiener process and geometric Brownian motion. The purpose of the paper is to compare the models for remaining useful life prediction with standard stochastic approaches and digital twin through real degradation data in order to find the comparison among them. Finally, the MATLAB digital twin model outperforms stochastic approaches in the early phases of prediction while remaining comparable in the latter stages. The paper could be used as a reference for further remaining useful life prediction research.
  Keywords: remaining useful life; digital twin; stochastic approach; bearing experiment.
  
  
• Post COVID-19 electrical load shedding on Cameroons northern interconnected grid: causes, safety impact and solution proposals  
  by Bouba Oumarou Aboubakar, HongXia Li, Ahmadou Bouba Oumarou 
  Abstract: This paper, after assessing and ranking power shortage causes in Cameroons northern interconnected grid, summarises the impact of power shortage on poor households and district hospitals. The results showed a drop of 40% of the supplied energy and the fluctuations of demand continued across the COVID-19 period till July 2021 after lockdown, thus a low influence of the pandemic. The results also revealed a low influence of temperature and precipitation on the energy crisis. Instead, it was found that the most important factor that led to power shortage was electricity production cost, which is higher than the market price. Out of seven hypotheses tested by the structural model developed, five were significantly supported and two were rejected. The hypothesis testing showed that electrical fire safety and patient care in hospitals are both positively significantly affected by load shedding, hospital management and users safety commitment and knowledge. Also, the results showed that neither safety knowledge nor safety impact is affected by demographic and socioeconomic variables. Using these results, a series of recommendations are given to energy practitioners and grid managers.
  Keywords: post COVID-19; load shedding; safety impact; structural equation modelling; Cameroon northern interconnected grid.
  
  
• Coordination reliability evaluation on raw material input and molten iron output for intelligent ironmaking system  
  by Jiahui Zhan, Yongjin Zhang, Yanjun Zhang, Tiejun Chun 
  Abstract: In intelligent ironmaking, the coordination reliability is of importance on the health condition of a blast furnace (BF) system. According to the basic principle of BF ironmaking, this paper proposes a method of measuring the coordination reliability using the input-output data of the BF system. The proposed method takes the difference between raw material input and molten iron output as an indicator to measure the coordination reliability. Real-time monitoring data and the functional relationship between raw material input and iron output are considered to formulate the coordination reliability model of a BF ironmaking system. By using the adjusted sampling technique, the batch sampling acceptance scheme is further developed on the coordination reliability of the BF ironmaking system. The data of one 1080 cubic-metre BF system is analysed to validate the proposed method.
  Keywords: coordination reliability; evaluation model; intelligent ironmaking system; batch sampling acceptance scheme.