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.

The application of parametric reliability analysis methods for repairable units, such as Power law process, is quite clear and straightforward for a single repairable unit. However, in practice, the analyst needs to know the reliability characteristics of units at a fleet level. The application of parametric reliability analysis methods at the fleet level, even if it is limited in scope, is quite complex. The aim of this paper is to describe the use of the power law process for multiple repairable units with differing reliability characteristics, to predict the expected number of failures at fleet level. The empirical data used in the paper are based on field data gathered during the operational life of two types of multi repairable units used in the Swedish military aircraft system FPL 37 Viggen from 1977 to 2006. The paper performs the trend test using TTT-based MIL-HDBK-189 and Laplace tests, and assesses the equality of shape-parameters for the intensity function of the power law process for multiple units. Estimation of the scale- and shape-parameters using maximum likelihood estimation is also performed. The parametric approach using power law process was found to yield relatively accurate estimations of number of failures, compared to empirical data.

This paper presents a reliability based design study of multilayered composites for electromagnetic interference shielding applications. In this study, uncertainties in the design and external variables affecting the shielding effectiveness (SE) are modeled based on probability distributions. Monte Carlo simulation is employed at each design point generated via Latin hypercube sampling approach to evaluate the probability of failure from the limit state function. Subsequently, a response surface approximation is employed to approximate the probability of failure in terms of design variables. This approximated polynomial is used to compute the probabilistic constraint in the design optimization. The design problems so formulated are solved using the real-coded genetic algorithm. The plane wave SE theory approach based on transmission line modeling for the multilayer shields in arbitrary polarized and incident direction of electromagnetic wave is adopted for SE calculation. The proposed approach is illustrated through examples by considering the military and commercial shielding requirements.

Brushless DC (BLDC) motor fan is one of the most widely used electronic components for thermal management. Failures of fans will cause seriously problems, such as overheat, shut down and even burnt, in their host systems. Thus, anomaly detection of fan gains increasing attention. This paper investigates into anomaly detection of generalized-roughness bearing faults in BLDC motor fan using current monitoring technique. In the experiment, it was found that there were about 9% changes in current and rotary speed of fan when the BLDC motor behaved unusual. Mathematical modeling of BLDC motor and physics-of-failure analysis were employed to explain the experimental findings.

The International of Journal of Performability Engineering is a refereed interdisciplinary journal which presents all engineering aspects of performance of products, systems or services. This journal was started in July 2005, and this year is in the tenth year of its publication. We like to present here how this journal has been progressing since its inception in 2005. Undoubtedly, we have come a long way and will continue making special efforts to ensure that we have participation and representation of all major countries of the world and the journal has a wide coverage of the topics within the planned scope of this journal. It is a matter of great satisfaction that the journal, in general, has been appreciated and has been received very well by the scientific community of the world. This is reflected through the demand /orders received for the copies of the papers published in this journal. We will of course continue to keep the standard of this journal very high and strive to provide high quality papers to our readers following a rigorous refereeing process involving competent reviewers so that the published papers are brief, precise and are of high standard.

We have been bringing out special issues in the important and new emerging areas of research and invite acclaimed researchers and practitioners to serve as Guest Editors in order to provide their interaction with researchers and professionals in the area.

IJPE also provides a unique facility to authors/researchers to present their new ideas before the scientific community through the medium of Short Communications/Short Papers, which otherwise might take quite some time to develop the idea into a full-fledged research paper.

Book reviews of latest books are often published in the journal to apprise our readership of new arrivals in the literature to keep them up-to-date in their respective area.

The details of IJPE issues published, during the period July 2005-Nov. 2013, are as follows:

List of 48 Countries which have contributed papers to IJPE: The following countries (in alphabetic order) contributed papers to the IJPE during this period:

Abu Dhabi, Algeria, Australia, Brazil, Canada, China, Czech Republic, Denmark, Egypt, Finland, France, Germany, Greece, Holland, Hong Kong, Hungary, India, Iran, Israel, Italy, Japan, Jordan, Korea (South), Kuwait, Latvia, Malaysia, Morocco, New Zealand, Norway, Oman, Pakistan, Poland, Portugal, Romania, Russia, Singapore, Slovenia, South Africa, Spain, Sweden, Switzerland, Taiwan, Turkey, Ukraine, United Kingdom, United States of America, Venezuela.

Major contributing countries happen to be (in alphabetic order): Australia, Canada, China, France, Germany, India, Israel, Italy, Japan, Norway, Sweden, South Korea, Taiwan, U.K., U.S.A. (The highest number of papers published have been from U.S.A.).

The journal is being abstracted by several scientific data bases, which include Elsevier’s SCOPUS, EI Village, Compendium, Google Scholar, ProQuest, INSPEC(UK), NSD (Norway), SCIMAGO etc. The number of citations from July 2005 to November 2012 for 305 papers published during the period has been 821.

We like to thank a large number of anonymous reviewers of papers, who over this period have given us their precious time and advice to keep the standard of this journal very high. We like to thank them here collectively and would like to record our gratitude to them.

Proposed Probabilistic Load Flow (PLF) approach, based on the method of cumulants, is used for bus voltage security assessment. The work accurately estimates the unknown probability distribution and density function of the involved complex random variables (CRV’s). With the help of these distributions a fast and accurate contingency ranking for security assessment is made possible. The advantage of the proposed method is that all possible contingencies are taken into account without complex convolutions and the method gives the densities and distributions of the variables in a single run. The method has been applied to the IEEE RTS 7-Bus test system which consists of 7 buses and 10 lines as well as the IEEE 24 bus system which consists of 24 buses and 38 lines. The information will be useful in operational decision making and ultimately help to improve the reliability of the power system.

Life test sampling plans are used to determine the acceptability of a product with respect to its lifetimes. Introducing acceleration in life testing experiments helps in obtaining estimates of reliability measures of high reliability products quickly. An accelerated life test (ALT), with linearly increasing stress is a ramp-stress test. This paper deals with a design of optimum time-censored ramp-stress accelerated life test sampling plan (ALTSP) where the product life is assumed to follow log-logistic distribution. The operating characteristic function of the uniformly most powerful (UMP) life test is deduced. The decision criterion is based on UMP test and the estimated median life time. The optimal plan consists in finding optimum sample size, sample proportions allocated to each stress, and stress rate factor by minimizing the expected total cost per lot. Bilevel-programming approach is used for this purpose. The method developed has been illustrated using a numerical example.

Based on longitudinal data, collected over a period of 16 years, this paper addresses how management responds to stakeholders’ concerns about the natural environment by prioritizing their activities and thus improving the environmental performability of the firms. The paper specifically seeks to answer how stakeholders' perceived influence develops over time and whether those changes affect firms' environmental activities. Starting in 1995, and every fourth year following, we distributed a pre-tested structured questionnaire to a random sample of small and medium-sized industrial firms in Denmark. Despite the continuing economic crisis, our findings indicate that environmental management initiatives have successfully moved up on industry’s strategic agenda to become an enduring or lasting endeavor for Danish firms. Before closing, key implications for corporate managers and other affected decision-makers are addressed.

The reliability evaluation of interconnection networks is an important issue in their quality management. Some important reliability measures are network reliability or g-terminal reliability, terminal reliability or 2-terminal reliability and k-terminal reliability. This paper concentrates on evaluating these three different reliability measures of interconnection networks. In this context a new method based on self generating disjoint minimal cut-set is proposed for evaluating the reliability of the interconnection networks. As, the minimal cut-sets thus generated are self-disjoint and non-redundant; it saves the overhead due to disjointing process and eliminates the duplicates. The method is well supported by an efficient algorithm for calculating the different reliability measures of interconnection networks. The proposed method as well as the algorithm is illustrated with a suitable example. The proposed method is compared against some existing methods in order to ensure its simplicity and efficiency in computing the reliability of interconnection networks. Further to show the generality of the proposed method the reliability of some regular interconnection networks are evaluated by using the proposed method.

Feature extraction is crucial to efficiently diagnose fault. This paper discusses a number of time-domain statistical features, including Kurtosis or the Crest Factor, the Mean by Deviation Ratio (MDR), and Symbolized Sequence Shannon Entropy (SSSE). The SSSE reflects the spatial distribution of the signal which is complementary with the statistical features. A new feature, Normalized Normal Negative Likelihood (NNNL), is used to improve the Normal Negative Likelihood (NNL). A Separation Index (SI) called the Extended SI (ESI) evaluates the performance of each feature and to remove noise feature. The Multi-Class Support Vector Machine (MSVM) recognizes bearing defect patterns. A numerical case is presented to demonstrate these features, their feature subset selection method and the pattern recognition method. The MSVM is used to detect three different types of bearing defects: defects in the inner race, outer race and bearing ball.

This article examines the performance of Minimax Probability Machine Regression (MPMR) for prediction of settlement(s) of shallow foundation on cohesionless soil. MPMR maximizes the minimum probability that future predicted outputs of the regression model will be within some bound of the true regression function. Width of footing (B), net applied pressure (q), average Standard Penetration Test (SPT) blow count (N), length (L), and embedment depth (Df) have been adopted as inputs of the MPMR. A sensitivity analysis has been carried out to determine the effect of each input. The results of MPMR have been compared with the Artificial Neural Network (ANN).