In this issue, we have included 10 papers presenting interesting research or case studies on different aspects of performability engineering. Generally, we always had more number of papers from researchers outside India than from India. This is the first issue in which papers from outside India and from India are equally distributed signifying keen interest in the area..

The literature in the past has focused primarily on reliability evaluation based on single node pair capacity requirements. In the first paper from India, a new reliability measure, as multi node pair capacity related reliability (MNPCRR), and an algorithm to evaluate this measure are proposed. This measure, authors claim is expected to help network designers in assessing and optimizing network performance and its effectiveness.

Embedded OSS is gaining a lot of importance these days, particularly for application with Android, Busybox but it presently suffers from quality and customer problems. So the second paper from Japan presents an approach for assessing software reliability based on flexible hazard rate model and formulates a total expected software cost model considering the environment for the usage of mobile device.

The third paper from Jordan attempts to investigate the critical factors and issues that are responsible for poor performance of existing software reliability models. The author identifies reasons attributable to 14 flaws which inhibit the improvement of software reliability modeling.

The fourth paper from India, tries to develop a list of Critical Success Factors for TQM implementation in Indian industries by doing a comparative study of 21 major 'National Quality Awards' and 14 frameworks as developed by various researchers. Then, using Principal Component Analysis, the paper proposes a new model for TQM implementation, which authors claim can help achieve manufacturing excellence and enhance competitive abilities of the industries.

The fifth paper jointly from Australia and U.S.A. presents a dynamic programming (DP) scheme to solve the problem of designing a network topology with maximum (s, t) reliability subject to given constraints, such as the computer centers location (nodes), their connecting links reliability and cost, and the maximum budget cost to install the links and suggests five different path-orders are proposed to improve the effectiveness of DPA.

Security authentication verifies the identity of an entity in a networked system. Risk assessment of an authentication mechanism is paramount to assure the security of a system. Though performability engineers have extended model-based evaluation techniques to assess security attributes such as system availability, confidentiality, and data integrity, authentication has so far not been found any connections to classical dependability measures. The sixth paper from U.S.A. presents a predictability model to quantify the risk of authentication violations. A RFID-based Electronic Toll Collection (ETC) system, demonstrates that the approach provides a useful metric.

The seventh paper from India presents reliability computation of a rotary system where reliability not only depends on the static design stresses but also on dynamic forces generated during operation by factors such as imbalance, misalignment, oil whirl, bend shaft, mechanical looseness etc. A model is proposed to incorporate the effect of imbalance mass on the reliability of rotary systems. The effect of rotating speed on reliability can also be assessed by this model.

The eight paper from U.S.A. presents an approach to validate computational models in the design space under uncertainty. The idea is to first characterize the model bias; then correct the original model prediction by adding the characterized model bias in the design space. A two-step calibration procedure is proposed and the model bias at each design configuration is approximated using the Maximum Entropy Principle (MEP) method.

The ninth paper is from an Indian private business entity representing ReliaSoft presents basically a tutorial case study on a compressor to demonstrate how their organization can help in reliability and maintainability studies.

The tenth paper also from India presents a case study on availability evaluation using Markov approach for a typical coal-fired power plant and identifies critical sub-systems and indicates plans for the preventive maintenance schedule.

In the end, I would like to thank all the authors who have contributed to this issue. I also like to record my appreciation and special thanks to all the anonymous referees who refereed papers and cooperated in maintaining the time schedule.

This paper proposes a cut set based approach to evaluate reliability of undirected capacitated networks for given simultaneous capacity requirements for specified multiple node pairs of the network. The capacity related reliability measures presented in literature have focused primarily on single node pair capacity requirements. However, networks need to support simultaneous demands for network resources for various node pairs. Therefore, a new reliability measure, as multi node pair capacity related reliability (MNPCRR), and an algorithm to evaluate this measure are proposed in this paper. The proposed algorithm takes link capacity and reliability values; minimal cut set and required capacities for each of the specified node pair as inputs to compute MNPCRR. Evaluation of this measure is expected to help network designers in assessing and optimizing network performance with ease and effectiveness. It will further help by providing sensitivity of the MNPCRR index to various link reliability parameters and capacities.

An embedded OSS known as one of OSS’s has since been gaining a lot of attention in embedded system area such as Android, BusyBox, etc. However, the poor handling of quality and customer support prohibit the progress of embedded OSS. In this paper, we propose a method of software reliability assessment based on a flexible hazard rate model considering the influence of installer application. Also, we derive several reliability assessment measures. In particular, we show several numerical examples of reliability assessment based on our hazard rate model. Moreover, we formulate a total expected software cost model considering the environment for the usage of mobile device. Then, we discuss about the determination of optimum software release times minimizing the total expected software cost.

The primary intention of the present study is to investigate the critical factors and issues that are accountable for poor performance of software reliability models. Critically reviewing the literature indicates that software reliability models have not delivered fully the desirable outcomes that they are intended to achieve. The findings of the current stuffy reveal that the reasons for performance incompetence of the software reliability models in effectively improving the reliability of the software are attributed to 14 major flaws. The implications of these flaws on the performance of software reliability models’ have been explored.

Many firms have arrived at the conclusion that effective TQM implementation can improve their competitive abilities and provide strategic advantages in the marketplace. There are many approaches used for the implementation of TQM in the industry. These approaches are either based on number of National Quality Awards (NQA’s) as developed by the governments of various countries or on the basis of frameworks as provided by various researchers. This paper tries to develop a comprehensive list of Critical Success Factors for TQM implementation in Indian industries by doing a comparative study of 21 major ‘National Quality Awards’ and 14 frameworks as developed by various researchers. Then, using Principal Component Analysis, the paper proposes a new model for TQM implementation, which can be significantly useful for achieving manufacturing excellence and thus adding to the competitive abilities of the organizations.

This paper addresses an NP-hard problem of designing a network topology with maximum (s, t) reliability subject to given constraints, such as the computer centers location (nodes), their connecting links reliability and cost, and the maximum budget cost to install the links. Cost is a major issue in the network design, and thus the problem is applicable for networks requiring maximized reliability. This paper presents a dynamic programming (DP) scheme to solve the problem. Then, it describes a DP approach, called DPA, to generate the topology using all (s, t) paths in the network. Five different path-orders are proposed to improve the effectiveness of DPA. Further, the path-orders allow DPA to generate only k=1 paths dynamically from the graph model of the network and stops if a path inclusion leads to an insignificant addition in the resulting topology’s reliability. This step reduces the time complexity significantly while producing almost equal results as compared to using all (s, t) paths. Extensive simulations using benchmark networks with various sizes show the merits of path-orders, and the effectiveness and advantage of our DPA vis-à-vis to three existing techniques. Our proposed DPA is able to generate 92% optimal results on the networks using only 6% to 11% of the (s, t) paths for large networks. Further, its non-optimal results are no more than 0.77% off that of optimal. Finally, for a 2×100 grid network that contains 299 paths, DPA requires only up to k=987 paths to generate topology with cost 99% of the total cost and reliability 99.35% of that of the original network.

Security authentication verifies the identity of an entity in a networked system. Risk assessment of an authentication mechanism is paramount to assure the security of a system, especially for today's ubiquitous deployment of Radio Frequency Identification (RFID) systems. Though experts in performability engineering have extended model-based evaluation techniques to assess security attributes such as system availability, confidentiality, and data integrity, authentication has so far not been found any connections to classical dependability measures. This paper presents a predictability modeling approach to quantify the risk of authentication violations. It measures the uncertainty, i.e., unpredictability, associated with system behavior. An exemplary networked system, a RFID-based Electronic Toll Collection (ETC) system, demonstrates that the approach provides a meaningful metric.

The focus of this paper is on reliability computation of rotary systems. Rotary systems reliability depends not only on the static design stresses but also on dynamic forces generated during operation. These systems are subjected to many sources of dynamic forces such as imbalance, misalignment, oil whirl, bend shaft, mechanical looseness and so on. The major source of problem of a rotary system, viz, the imbalance is considered in this paper. A model is proposed to incorporate the effect of imbalance mass on the reliability of rotary systems. The effect of rotating speed on reliability can also be assessed by this model. A stress-strength interference approach together with a simulation-based methodology is used for modeling and analysis of this complex relationship. Illustrative examples are provided for demonstrating the practical utility of the approach.

This paper presents an approach to validate computational models in the design space under uncertainty. The basic idea is to first characterize the model bias; then correct the original model prediction by adding the characterized model bias in the design space. Particularly, a two-step calibration procedure is proposed and the model bias at each design configuration is approximated using the Maximum Entropy Principle (MEP) method. With the characterized model bias at several design configurations, response surface of the model bias is finally constructed to approximate the model bias at any new design configurations. Two examples including a modified vehicle side impact problem and a thermal problem are used to demonstrate the feasibility of the proposed approach.

Reliability engineering in the process industry has received a lot of attention in recent years, and many tools and techniques are available, such as Reliability, Availability and Maintainability (RAM) modeling, Reliability Centered Maintenance (RCM), etc.

This paper deals about a case study of a utility plant which is supplying compressed air to the aluminium smelter plant. The compressor has been identified for this study based on the business criticality. There are seven compressor installed in the plant. Each compressor has an integrated dryer unit and all are needed for the plant operation. Weak points have been identified based on RCM study. Each compressor has four failure modes in series and dryer has two failure modes in series. RBD has been created based on the reliability wise connection. The failure and repair distribution have been calculated based on maintenance log data using statistical models i.e. Life Data Analysis (LDA). This information has been used in RBD as block properties. Results of cost benefit analysis have been presented by comparing before and after implementation of strategic maintenance action/task based on RCM analysis.

This article presents the performance (availability) evaluation of a typical coal-fired power plant in a realistic working environment for identifying the critical sub-system and planning the preventive maintenance schedule. For analysis, the entire thermal system is broken down into six sub-systems i.e., turbine, condenser, coal supply, water circulation, air circulation and boiler sub-systems; these are further subdivided into a number of units. Formulation for availability of each sub-system is based on well-known Markov birth-death process. Sensitivity analysis is performed to identify critical units in each sub-system. The overall availability index of coal fired plant is evaluated by combining all six sub-systems. Results revealed that water circulation is a robust sub-system, while boiler along with Fi unit (combined of furnace, boiler drum, tubings and fuel firing) is most critical for given failure and repair rates of each unit. For failure free plant operation, the repair priority of boiler and its unit Fi should be accorded.

This article considers a Circular Consecutively Connected System (CCCS) consisting of N ordered nodes connected in a circle, which fails if any two nodes are disconnected. Previous studies on the reliability of CCCS have mainly assumed that the connection between any pair of nodes is unidirectional. In this article, a Universal Generating Function (UGF) method is proposed to evaluate the reliability of CCCS where the connection between any pair of nodes is bidirectional. An example is presented to illustrate the application of the method.