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, No 5
  • Editorial
    September 2012 Editorial
    2012, 8(5): . 
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    There is good news from Dr. Anthony Doyle, Senior Editor Engineering, Springer Verlag, London. On May 30, 2012, Dr. Doyle informs me that the Handbook on Performability has set a sort of record as follows:

    “You are surely aware that your book Handbook of Performability Engineering is published in both print and electronic formats. Today, we would like to update you on the chapter downloads of your eBook on Springer Link, Springer's online platform.

    Since its online publication on Aug 27, 2008, Handbook of Performability Engineering has received a total of 28810 chapter download requests. Over the last year(s) the download figures have been as follows:


    As you can see, in addition to the print book, the electronic version offers a broad readership and increased visibility for your work. This is especially noticeable in the long run: statistical data shows that the usage of electronic publications will continue to be stable for years.

    Thank you again for publishing with us. We are very pleased to disseminate your book among the scientific community and look forward to working with you on your next book or journal article."

    Obviously, this is indicative that the Handbook on Performability Engineering has been received very well by the international scientific community and there is keen interest in the subject matter.

    Encouraged by the response of the scientific community to Handbook on Performability Engineering, it has been decided to bring out a Book Series on Performability Engineering. This Book Series on Performability Engineering shall be published by Scrivener Publishing LLC, U.S.A. which has a strategic partnership with John Wiley & Sons whereby they are responsible for all global print and electronic sales of Scrivener Publishing. The editors of this book Series are myself, and Professor John D. Andrews, of Nottingham University, U.K. who is also one of the Editors-in-Chief of International Journal of Performability Engineering. We would be happy to receive proposals of books from the prospective authors/editors in the area of performability engineering, viz, on quality, reliability, maintainability, safety, risk, and sustainability. The format for preparation of a detailed proposal can be had from the undersigned on request and has been also provided elsewhere in this issue.

    We are also encouraged by the orders that we have been receiving from many countries for the copies of the papers that have been published in the past in various issues of the International Journal of Performability Engineering.

    We also like to inform our readers that there has been a steady increase in the flow of papers to this journal and due to increase in the quantum of acceptable papers, we have increased the number pages per issue from 100 earlier, to 120 pages from May 2012 and we have now been publishing 10-11 papers per issue since May 2012 and all papers have been reviewed and revised to keep the standard of the journal very high. A status report on IJPE follows on the next page.

    In the present issue also, we have published 11 papers and we hope that the readers of IJPE will find the papers presented here interesting and stimulating which is the objective of this journal.

    Original articles
    False Target vs Protection in Defending Parallel Systems against Unintentional and Intentional Impacts
    2012, 8(5): 465-478.  doi:10.23940/ijpe.12.5.p465.mag
    Abstract    PDF (194KB)   
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    This article considers a parallel system exposed to external intentional impacts caused by malicious attacks, and unintentional impacts caused by natural disasters or technological accidents. The defender distributes its resource between the deployment of false targets and the protection of genuine system elements. The deployment of false targets is intended to misinform the attacker so that it is not able to distinguish between the false targets and the genuine system elements, which leads to dissipating the attack resources. Different combinations of unintentional and intentional impacts sequences are considered. The vulnerability of each system element is determined by an attacker-defender and unintentional impact-defender contest success functions. A framework of solving the optimal defense resource distribution which minimizes the overall system vulnerability is suggested. Illustrative examples are presented.

    Received on October 06, 2011 and revised on July 09, 2012
    References: 26
    New type of RBF Networks in Graph Applications
    2012, 8(5): 481-488.  doi:10.23940/ijpe.12.5.p481.mag
    Abstract    PDF (123KB)   
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    Gantt charts are a common technique for representing the phases and activities of a project or a process work breakdown structure (WBS), so that they can be understood by a wide audience. Because the horizontal bars of a Gantt chart have a fixed height, they can misrepresent the time-phased workload (resource requirements) of a project, which may cause confusion especially in large projects.This paper shows a new approach of rendering the graph point series called Gantts. In our application, Gantts are placed in the two dimensional graph which contains the information about available production sources in the real manufacturing process. To provide a comfortable appearance, Gantts are accompanied with the description text giving detailed information about each Gantt such as name, required amount of item, etc. All Gantt descriptions must be displayed without any overlapping with each other. We applied the modified version of the RBF (Radial Basic Function) neural network with biases to optimize this task. With respect to the similarity to the RBF structure, the new type of neural network was named RBF 2. We also offer the idea of positive and negative attributes of the solution based on the neural network architecture.

    Received on March 11, 2011, revised on May 27, 2011, May19, 2012 and July 10, 2012
    References: 8
    Vague Reliability Analysis Using Vague Differential Equations
    2012, 8(5): 489-496.  doi:10.23940/ijpe.12.5.p489.mag
    Abstract    PDF (120KB)   
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    In this paper, the concept of fuzzy differential equations (FDEs) is extended by vague differential equations (VDEs) and a new method to find the analytical solution of VDEs with new representation of trapezoidal vague set (TrVS), named as JMD TrVS, is proposed. To show the application of proposed method in real life problems the vague Kolmogorov's differential equations (VKDEs), obtained by using Markov model of piston manufacturing system (PMS), are solved by proposed method and with the help of obtained solution vague reliability of PMS is evaluated.

    Received on August 12, 2011, revised on May 24, 2012 and July 05, 2012
    References: 10
    Reliability and Spare Parts Provisioning Considering Operational Environment: A Case Study
    2012, 8(5): 497-506.  doi:10.23940/ijpe.12.5.p497.mag
    Abstract    PDF (272KB)   
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    Industry with a high level of investment, such as the oil and gas industry, needs a high level of availability. Product support and its related issues such as spare parts play an important role in maintaining a system at a desired level of availability. Reliability performance is a critical factor for product support and spare parts planning which can be influenced by operational environment. Therefore, all influence factors (covariates) on reliability performances must be considered in order to predicate the required number of spare parts. The available reliability based methods for forecasting spare parts have given less attention to quantifying the effect of covariates. The aim of this paper is to study the effect of time-dependent and time-independent covariates on the prediction of spare parts using a real case study.

    Received on June 06, 2011, revised on September 29, 2011 and June 30, 2012
    References: 12
    Structural Safety Evaluation Using Inverse Measure Approach
    2012, 8(5): 507-513.  doi:10.23940/ijpe.12.5.p507.mag
    Abstract    PDF (111KB)   
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    High reliability and operational safety are most important requirements of aerospace products. Structural Safety (Reliability) assessment techniques help to achieve safe designs and also identify effect of uncertainty occur in structural systems of aerospace products. In general the structural safety is evaluated using various statistical methods like Mean Value and Moment Methods. Currently several inverse reliability measures such as Probabilistic Performance Measure (PPM) and Probabilistic Sufficiency Factor (PSF) have been introduced as measures of safety. In the present paper, thin Maraging steel cylindrical pressure vessels which are extensively used in space vehicle applications are considered for safety evaluation using Probabilistic Performance Measure (PPM) and is demonstrated with a practical case.
    Received on July 27, 2011, and revised on June 13, 2012
    References: 15

    Semi-Markov Modeling Approach for Deteriorating Systems with Preventive Maintenance
    2012, 8(5): 515-526.  doi:10.23940/ijpe.12.5.p515.mag
    Abstract    PDF (252KB)   
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    Software systems experience gradual performance degradation despite of which they are required to perform service, though at a degraded level. Different preventive and corrective techniques (restart, rejuvenation etc.) have been applied to restore efficient service of the system. In this paper, we model the process of degradation together with the corrective actions of minimal repair, major repair and restart technique via a semi-Markov process. In addition, at the lower level, we propose a performance model to study the impact of load on degradation, using Markov reward models. Closed-form solution for the dependability of the system in terms of availability, reliability and maintainability are obtained. The proposed model is also compared with an existing model. The analysis conducted, using numerical results, indicates the efficiency of our approach.

    Received on May 24, 2011, revised on January 16, 2012, and on June 15, 2012
    References: 14
    Performance Measurement of Depot Level Maintenance in Military Aviation Environment
    2012, 8(5): 527-537.  doi:10.23940/ijpe.12.5.p527.mag
    Abstract    PDF (183KB)   
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    The enormous asset dimension, in terms of investments, technology, lifespan and end use, of aerospace assets makes maintenance an important business process. The performance measurement of depot level servicing in military aviation calls for application specific set of metrics. The study brings out a multi-criteria and hierarchical framework for performance measurement of depot level servicing in military aviation. The framework has been developed based on a process reference framework, combined with broad organizational level perspective for military aviation maintenance. The framework is useful for managers for their maintenance decisions at various levels of a defense organization.

    Received on April 08, 2011 revised on September 19, 2011 and June 13,2012
    References: 5
    A Software Reliability Growth Model for Estimating Debugging and the Learning Indices
    2012, 8(5): 539-549.  doi:10.23940/ijpe.12.5.p539.mag
    Abstract    PDF (157KB)   
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    Most Software Reliability Growth Models (SRGMs) ignore either the learning phenomenon of the testing team or quality of debugging or both for the sake of simplicity. Some SRGMs consider imperfect debugging tightly integrated with the learning phenomenon. In practice, imperfect debugging and the learning phenomenon of the testing team are independent of each other since the former indicates quality of debugging process and the latter the quality of the testing process, usually carried out by different teams. Furthermore, sometimes the debugging team may find and correct some more faults in addition to the faults which caused the failures leading to what is known as efficient debugging. In this paper, a new mathematically derived SRGM is proposed, which also provides estimates of various quality metrics such as the number of faults in the software system, debugging and the learning indices. The proposed SRGM seems to describe the time to failure data of many software projects satisfactorily.

    Received on November 28, 2010, revised on June 17, 2011 and June 18, 2012
    References: 15
    Some Aerospace Engineering Applications of Reliability Growth: A Review
    2012, 8(5): 551-562.  doi:10.23940/ijpe.12.5.p551.mag
    Abstract    PDF (348KB)   
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    Reliability growth analysis is a tool for trending and monitoring component and system reliability during design, development, and fielded operations. It is robust with mixed failure modes and changing reliability levels and can predict future failures with reasonable accuracy. Several reliability growth case studies from aerospace engineering applications are presented as an overview to illustrate its utility for development, in-service, and management trending and risk assessment.

    Received on October 12, 2011, revised on May 12, 2012 and July 17, 2012
    References: 11
    Improving Maintainability in Extreme Cold Climatic Conditions
    2012, 8(5): 563-572.  doi:10.23940/ijpe.12.5.p563.mag
    Abstract    PDF (123KB)   
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    The maintainability issue is critical for the successful and effective operation of any industry in the extreme cold climatic conditions as the working conditions are made very difficult by low temperature, ice, short period of daylight and lack of support facilities. The objective of this paper is to identify potential risk factors in cold conditions and to provide ergonomic guidelines to reduce risk factors and increase maintainability of industries deployed in cold climate.

    Received on January 02, 2011, revised on September 02, 2011 and July 09, 2012
    References: 26
    Short Communications
    Optimal Design for Accelerated Life Testing with Simple Step-Stress Plans
    2012, 8(5): 573-577.  doi:10.23940/ijpe.12.5.p573.mag
    Abstract    PDF (189KB)   
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    This paper presents the optimal design for accelerated life testing (ALT) experiments when step-stress plans with Type I censoring are performed. We adopt a generalized Khamis-Higgins model for the effect of changing stress levels. It is assumed that the lifetime of a test unit follows a Weibull distribution, and both its shape and scale parameters are functions of the stress level. The optimal plan chooses the stress changing time to minimize the asymptotic variance (AVAR) of the Maximum Likelihood Estimator (MLE) of reliability at the use stress level and at a pre-specified time.

    Received on March 14, 2012, revised on April 22, 2012
    References: 09
    Quality and Replication of Microarray Studies
    2012, 8(5): 578-582.  doi:10.23940/ijpe.12.5.p578.mag
    Abstract    PDF (94KB)   
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    Quality assessment of DNA microarrays uses different spot parameters that contain complete information to describe each microarray and detect corrupted spots. Images obtained through replication should result in improved quality as measured according to parameters. We propose methods to determine the number of replicates required to achieve a certain level of quality, and present an application to the parameter known as Background.

    Received on May 11, 2010, revised on July 26 and August 20, 2010, and June 30, 2012
    References: 28
ISSN 0973-1318