Abstract:

In this issue again, as usual, we present 8 full papers representing various aspects of performability engineering.

The first two papers are from reliability area. While the first one presents a parametric approach using power law process for assessing reliability of multiple repairable units, the second paper presents a reliability based design of multilayered composites used in electromagnetic shielding.

The third paper is related to maintainability aspect of performability and uses current monitoring technique to predict the failure of a brushless D.C. motor used in fans employed for cooling of devices such as hard disk drives and CD-ROMs etc. The fourth paper of the issue is related to security or safety aspect of performability and presents a technique which has the advantage that all possible contingencies are taken into account through probabilistic load flow (PLF) that uses the method of combined cumulants. without complex convolutions and provides the densities and distributions of the bus voltages and line flows in a single run. The system operator can utilize the information of security assessment to improve availability of a power system.

The fifth paper uses Bilevel-programming approach for obtaining optimum plan consisting of finding optimum sample size, sample proportions allocated to each stress, and stress rate factor by minimizing the expected total cost per lot for time-censored ramp-stress accelerated life test sampling plan (ALTSP) where the product life is assumed to follow log-logistic distribution. The sixth paper addresses the question of environmental sustainability and shows how the management should respond to stakeholders’ concerns about the natural environment by prioritizing their activities and thus improving the environmental performability of the firms, particularly, indicates that environmental management initiatives have successfully moved up on industry’s strategic agenda to become an enduring endeavor for Danish firms.

The seventh paper presents a new method which finds self-generating disjoint minimal cut-sets of an interconnected network or system without duplication and the system reliability is evaluated by considering corresponding links of the generated minimal cut sets. Thus, eliminating the computational task needed for the disjointing process of earlier approaches presented in the literature.

The eighth paper of the issue presents time domain features of vibration signal analysis and proposes some new ones; which include features adopted from another field and improved upon the existing ones. A separation index is proposed to remove noise feature, and a commonly used subset selection method chooses the optimal subset of features. The optimal subset features are used as Support Vector Machine (SVM) input to diagnose fault in a roller bearings, which is a critical member of rotating machine which can lead to high unavailability.

The highlights of this year’s issues will be two special issues planned on Sustainability, viz., the one on Balancing Technology, Environment and Lifestyles, which will be published in June 2014 and the other on Design of Products, Systems and Services for Dependability and Sustainability, as the extra issues over and above the six scheduled issues of IJPE every year since 2010. Prior to 2010, the journal was a quarterly journal with the exception of 2007 and 2009 when five issues were published in a year. These two extra issues will highlight the relevance of consideration of sustainability in design of engineering products, systems and services. This year with July issue, we will be completing ten years of publication of International Journal of Performability Engineering. On page 271, we present an update on IJPE’s success during this decade.

This indicates that our effort to extend the concept of performability to include sustainability as design parameter besides dependability (quality, reliability, maintainability and safety) was a step in the right direction. With sustainability gaining importance in 21^st Century, we can’t but give it a place of importance, particularly in the design of engineering products, systems and services to conserve material energy and arrest environment pollution. This journal will keep on striving to presents new ideas in this endeavor to achieve goal of producing sustainable systems and services.

My sincere thanks are due to all those authors of 393 papers (comprising nearly 5000 printed pages) from 48 countries, whose contributions have been published in the 47 issues of IJPE since the start of this journal in July 2005. This makes IJPE as a journal which publishes over 8 papers per issue on an average.

I would be failing in my duty as an Editor-in-Chief of this journal, if I do not acknowledge the uninhibited support of reviewers and referees who helped maintain high standards of publication of this journal.

I would like to assure our readers that we will continue to present various aspects of performability engineering and new research to our readers through this journal in the years to come.