International Journal of Reliability and Safety (5 papers in press)

Regular Issues

• Reliability assessment and performance analysis of DFIG-based wind turbines for wind energy conversion system  
  by Om Prakash Bharti, R.K. Saket, S.K. Nagar 
  Abstract: This paper presents the reliability assessment and performance analysis of doubly fed induction generator (DFIG)-based wind turbines (WT) for accurate DFIG-based WT modelling. This model calculates and describes the reliability of each unit and component of the WECs by using the Markov process. To analyse the DFIG-based WT during transient and steady-state operations, both the control and modelling of the system are illustrated in detail. The main contribution of this paper is the reliability assessment of the DFIG-based WT units in terms of failures as well as repair rate and performance analysis in normal as well as faulty conditions. For fault analysis of the WECs, a DFIG-based WT has been simulated in MATLAB Simulink for line to line, line to ground and double line to ground fault study.
  Keywords: renewable energy; wind energy conversion systems; wind turbine; synchronous generator; permanent magnet synchronous generator; doubly fed induction generator.
  
  
• Probabilistic evaluation and design aspects for reliability enhancement of induction motors  
  by Sanjay Kumar, Sachin Kumar, Om Prakash Bharti, Lokesh Varshney, K.S. Anand Kumar, R.K. Saket, D.N. Vishwakarma 
  Abstract: This paper presents the probabilistic evaluation, design aspects and scientific suggestions to improve the reliability and performance of an industrial induction motor. The induction motors have experienced a long life and a high efficiency in service with appropriate design and quality control. However, reliability quantification and adequacy evaluation are still necessary and important for customer satisfaction, design improvement, marketing, vendor selection, production plan, service life determination and scheduled maintenance. The industrial data related to manufacturing and failure of induction motors are analysed for reliability assessment and design suggestions. The reliability indices, such asMTBF and failure rate of induction motors, are evaluated using industrial data based exponential distribution function, which is issued to plan the maintenance schedule of the industrial induction motors. The technological suggestions are finally presented in this paper to reduce the failure rate and enhance the MTBF for reliability improvement of induction motors.
  Keywords: probabilistic evaluation; design aspect; induction motor; reliability improvement; MTBF; MTTF; failure rate; exponential distribution function.
  
  
• Parametric selection of software reliability growth models using multi-criteria decision making approach  
  by Rakesh Garg 
  Abstract: The present research aims at the development of a computation procedure based on the mathematical procedures to solve the problem of software reliability growth models (SRGMs) selection problem. The present selection problem is carved as a multi-criteria decision making (MCDM) problem in this study and an MCDM approach, namely VIseKriterijumska Optimizacija I Kompromisno Resenje (VIKOR) is implemented to solve the same. To demonstrate the working of the VIKOR, two real-time failure datasets have been used on which 16 SRGMs are evaluated against a set of total 12 selection indexes. The present study produces a comprehensive ranking of the various SRGMs based on their relative proximity as the result. The model having the smallest proximity value is graded at position-1 and the model with largest proximity value on the last position.
  Keywords: software reliability; software reliability growth models; NHPP; multi-criteria decision making; selection indexes; VIKOR.
  
  
• On the mixture of flexible Weibull extension and Burr XII distributions  
  by Rania M. Kamal, Moshira A. Ismail 
  Abstract: This paper is devoted to study a new mixture model. This newly suggested model is a mixture of flexible Weibull extension and Burr XII distributions. We study the characteristics of the proposed distribution that includes probability density function, cumulative distribution function, reliability function and ageing behaviour through the failure rate function. Some statistical properties of the proposed distribution, such as quantile function, the mode, median, rth moments, the moment generating function and the order statistics, are discussed. Moreover, the method of maximum likelihood is proposed for estimating the model parameters, and also the Fishers information matrix is derived. Finally, the performance of the proposed distribution is compared with existing distributions using applications of two real datasets to show the flexibility and efficiency of the new model.
  Keywords: mixture models; flexible Weibull distribution; Burr XII distribution; reliability; failure rate function; quantile function; moments; order statistics; estimation; Fisher’s information matrix.
  
  
• Complementary optimal age maintenance policy for repairable systems  
  by Nse Udoh, Effanga Effanga, Christian Onwukwe 
  Abstract: A complementary optimal age maintenance policy is proposed in this work for repairable systems that require a high level of availability and safety standard by exploiting the comparative advantage of minimum expected cost-based optimal age replacement policy and maximum limiting availability-based optimal age replacement policy. The failure distribution, cost of preventive and failure maintenance and downtime of preventive and failure maintenance, which affect the age at which an operating system is replaced, were used to formulate the expected cost and limiting availability functions for repairable systems.
  Keywords: repairable system; failure distribution; cost and availability functions; replacement maintenance.