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, No 1
  • Editorial
    K. B. Misra
    2013, 9(1): 1.  doi:10.23940/ijpe.13.1.p1.mag
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    As usual, in this first issue of the ninth year of publication of International Journal of Performability Engineering, we bring to our readers 10 new papers and one Short Communication, which together provide several new techniques and applications in the upcoming areas of performability engineering.

    The first paper of this issue provides a new sampling plan for censored life testing when life time follows Weibull distribution, whereas the next paper of the issue proposes a new approach to software performability considering the aspect of collusion status during the binding-phase of open source softwares in open source solution. This is a new paradigm to reduce cost and quick delivery. The next paper provides an an important tool of assessing the condition of a power transformer using Disolved gas Analysis and Partial Discharge measurement. This technique would help predict the incipient breakdown of the power transformer insulation well in advance and help avoid the failure of power transformer. The next paper is on energy saving strategies for a building with glazed fa?ade when it is exposed to Sun. This study can help evolve environmentally favourable and sustainable solutions for energy saving in buildings particularly in tropical zone. The next paper of the issue compares the efficacy of two pattern recognition approaches for fault detection, viz., Artificial Neural Networks (ANN) and Support Vector Machines (SVM) as it is crucial for developing an efficient approach for fault diagnosis.

    The sixth paper of this issue discusses the effect of network size, transmission range, and network coverage area, on the reliability measures of MANETS by modeling them as Geometric Random Graphs. The reliability of these ad hoc network is the most challenging and interesting area because of changing of topology, particularly during emergency situations like human-induced disasters, military conflicts, emergency grounds, commercial applications etc. The next paper discusses the advances of clustering as clustering is a very important business strategy as propagated originally by Porter and is extended in this paper by the authors in enhancing a firm’s performability. The paper demonstrates the usefulness of clustering in case of Samsung Electric Corporation of South Korea. The next paper describes a four quadrant framework for characterizing print shops in the printing industry based on the workflow complexity and utilization of resources. The formalism of heavy tail distributions is used to characterize the extreme levels of variability observed in job size. Methods of quantifying and characterizing the variability are presented. The implementation of the LDP Lean Document Production solution in a large transaction shop is presented and is shown to deliver substantial productivity benefits. In the next paper, a new application of FMEA to an Off-shore Floating Desalination plant is made when the plant is run by an autonomous variable power source such as wind generator. This is a typical application paper. The last paper of the issue is again a typical application paper that optimizes the system availability of a Coal Handling Plant using Genetic Algorithms.

    In addition to the above papers, we also present a short communication that offers a new approach for evaluating reliability of a 1-out-of-(n+1) warm standby system subject to fault level coverage. It is sincerely hoped that this issue will generate considerable interest among our readers, who are looking for new ideas and applications in the field of performability engineering.

    Besides these papers, we have also included in this issue two important announcements –the first one is about a special issue of IJPE on Performance of Space Vehicles being guest-edited by Dr. William E. Vesely, of NASA Headquarters,, who is well-known for his generic contributions in reliability engineering and the other announcement is about starting a book series on Performability Engineering which has already contracted four books from authors of various countries and some more are in the pipeline.

    Original articles
    A New Failure Censored Variables Sampling System for Weibull Distribution
    2013, 9(1): 3-12.  doi:10.23940/ijpe.13.1.p3.mag
    Abstract    PDF (115KB)   
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    Reliability sampling plans are used to determine the acceptability of a product at some future point in its effective life. Whenever the life test is performed based on the measurement data, variables sampling plans can be utilized. Variables sampling plans are more efficient than the attribute sampling plans. In this paper, we propose a reliability sampling system for measurable characteristics under failure censored life testing when the life time of the product follows Weibull distribution with known shape parameter. In this proposed sampling system, the acceptance criteria do not involve the unknown scale parameter of the distribution differently from the existing sampling plans. The parameters of the proposed system are determined by using two points on the operating characteristic curve approach. To determine the optimal parameters, an optimization problem is formulated so as to minimize the average number of failures to be observed. It is also to be pointed out that the designing parameters can be done independently of the shape parameter although the operation of the system involves the shape parameter and a lower specification limit. The main advantage of the proposed system is to reduce the average failure number with desired protection.

    Received on April 08, 2011, revised on June 13, 2012, and June 17, 2012
    References: 13
    Performability Analysis Considering Debugging Behaviors for Open Source Solution
    2013, 9(1): 13-21.  doi:10.23940/ijpe.13.1.p13.mag
    Abstract    PDF (685KB)   
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    A large scale open source solution composed of several open source softwares is now attracting attention as the next-generation software development paradigm because of the cost reduction, quick delivery, and work saving. The testing phase of open source solution means the binding testing and system testing. Generally, it makes no sense to perform the unit testing of open source solution, because the unit testing means the test for open source software. Then, it is very important for software managers to assess the binding status of open source solution. In this paper, we propose a new approach to software performability analysis based on stochastic differential equations in order to consider an interesting aspect of the collision status during the binding-phase of open source softwares in open source solution. Especially, we derive several performability assessment measures from our stochastic differential equation model. Also, we analyze actual software fault-count data to show numerical examples of software performability assessment considering the component collision for several open source softwares. Moreover, we show that the proposed performability analysis can assist improvement of quality for the large scale open source solution.

    Received on February 16, 2012, revised on September 24, 2012
    References: 13
    Preventing Power Transformer Failures through Electrical Incipient Fault Analysis
    2013, 9(1): 23-31.  doi:10.23940/ijpe.13.1.p23.mag
    Abstract    PDF (217KB)   
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    The Dissolved Gas Analysis (DGA) and partial discharge (PD) level measurement are important tools for evaluating the condition of the insulation of a transformer, which is an indicator of the health of a transformer and cam help in prevention of the transformer failure. In this paper the PD level and dissolved hydrogen (H2) and acetylene (C2H2) gases in oil of an artificially aged/ stressed insulation system of a specially designed test cell have been analyzed and compared with the results of the experimental studies. Considering the various formulae existing in literature for the dependence of PD on applied voltage in high voltage equipment, regression analysis has been done. On analyzing the content of dissolved H2 and C2H2 gases in the oil, with the PD measurements, incipient conditions of PD and low energy arcing within a transformer can be used to distinguish. This is useful for timely detection of insulation degradation.

    Received on January 17, 2012, revised on August 08, 2012
    References: 10
    Energy Saving Assessment in Buildings with Varying Fa?ade Orientations and Types of Glazing Systems when Exposed to Sun
    2013, 9(1): 33-48.  doi:10.23940/ijpe.13.1.p33.mag
    Abstract    PDF (888KB)   
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    With the increasing awareness of sustainable development in the building construction the assessment of energy demands for heating/cooling under the influence of extended glazing fa?ade, type of glazing, building orientation and energy control management strategies have become more important. In this study, focus is given on the energy performance assessment of a building zone with an entirely glazed fa?ade, with four types of glazing at various orientations, by defining: (a) a desirable indoor zone temperature margin (ZTM) and (b) a desirable indoor minimum overnight temperature (MOT). Particular emphasis is given on the overheating during the summer season by introducing and evaluating the overheating temperature-index (OTI) for the examined glazing systems. The modeling and mathematical formulation is based on the thermal-network modeling approach with distribution of solar radiation on both the external and internal zone surfaces in 15 min time increments. Simulation results are given for a building zone located at the Mediterranean region.

    Received on December 27, 2011 and revised on August 28, 2012
    References: 11
    A Comparative Study of Artificial Neural Networks and Support Vector Machine for Fault Diagnosis
    2013, 9(1): 49-60.  doi:10.23940/ijpe.13.1.p49.mag
    Abstract    PDF (496KB)   
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    Fault detection is a crucial step in condition based maintenance requiring. The importance of fault diagnosis necessitates an efficient and effective failure pattern identification method. Artificial Neural Networks (ANN) and Support Vector Machines (SVM) emerging as prospective pattern recognition techniques in fault diagnosis have been showing its adaptability, flexibility and efficiency. Regardless of variants of the two techniques, this paper discusses the principle of the two techniques, and discusses their theoretical similarity and difference. Eventually using the commonest ANN, SVM, a case study is presented for fault diagnosis using a wide used bearing data. Their performances are compared in terms of accuracy, computational cost and stability.

    Received on November 20, 2011, revised on September 23, 2012
    References: 24
    The Influence of Scenario Metrics on Network Reliability of Mobile Ad Hoc Network
    2013, 9(1): 61-74.  doi:10.23940/ijpe.13.1.p61.mag
    Abstract    PDF (893KB)   
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    A wireless mobile ad hoc network (MANET) is a collection of solely independent nodes that communicate with each other by forming a single hop/multi-hop network, and maintain connectivity in a decentralized manner. The important characteristic of the ad hoc network is that the nodes move randomly around the area of deployment making the topology highly dynamic. Because of this configuration and absence of infrastructure, an ad hoc network has been in increasing demand during emergency situations like human-induced disasters, military conflicts, emergency grounds, commercial applications and so on. The reliability of the ad hoc network is the most challenging and interesting issue because of its changing topology. This paper addresses and illustrates the effect of few scenario metrics, viz., network size, transmission range, and network coverage area, on the reliability measures (i.e., 2TRm and ATRm) by modeling MANET as Geometric Random Graph.

    Received on November 2, 2011, revised on February 2, 2012, and June 29, 2012
    References: 26
    Enhancing Performability through Domestic and International Clustering: A Case Study of Samsung Electronics Corporation (SEC)
    2013, 9(1): 75-84.  doi:10.23940/ijpe.13.1.p75.mag
    Abstract    PDF (112KB)   
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    Clustering is a very important business strategy in enhancing a firm’s performability. Porter provided a seminal theory in this field, but it has three limitations. First, the current theory cannot explain how cluster emerges. Second, a narrow perspective on geographic configuration has limitations in explaining a variety of real business practices. Lastly, Porter’s cluster concept is domestically oriented and understates multinational activities in terms of enhancing corporate performability. Embracing these limitations, this paper extends Porter’s cluster theory and provides a more comprehensive view on the real business world. We then apply it to a successful cluster strategy used by Samsung Electronics Corporation to enhance its performability.

    Received on March 02, 2012 and revised on August 20, 2012
    References: 33
    Implementation of Lean Document Production in the Printing Industry
    2013, 9(1): 85-96.  doi:10.23940/ijpe.13.1.p85.mag
    Abstract    PDF (399KB)   
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    A previous Interfaces (Edelman Finalist) paper by Rai et al. [12] described the LDP Lean Document Production toolkit and work process based on operations research techniques that demonstrated significant improvements in the productivity of small to mid-sized print shops. In this paper, the extensions of the methodology to improve productivity of very large print shops are described. The printing industry is segmented into four quadrants based on resource utilization and job variability. Job variability in one of the industry segments is extremely high and is characterized by fat-tail distributions. This paper describes the extensions required to handle the applications of LDP Lean Document Production to this market segment.

    Received on January 01, 2012 and revised on September 21, 2012
    References: 23
    Application of FMEA to an Offshore Desalination Plant under Variable Environmental Conditions
    2013, 9(1): 97-108.  doi:10.23940/ijpe.13.1.p97.mag
    Abstract    PDF (391KB)   
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    In this paper, the evaluation of the effect of variable power is presented, which is caused from changing environmental conditions. These affect system operation which consists of a wind turbine which provides the necessary power and a desalination potable water production unit installed on a floating offshore structure. The integration of wind variations in the failure mode and effects analysis (FMEA) method is done with the addition of a factor that affects the estimation of occurrence rating and sometimes the potential detection rating. The experience from previous potable water reverse osmosis systems and machineries together with the data and literature from projects with offshore wind turbines were studied and applied to FMEA to improve the risk evaluation of the system. Finally, analyzing the results of RPN in this novel offshore floating desalination unit powered from wind turbine show how the substantial wind load variations extend the risk prioritization method beyond the conventional risk priority number (RPN) method.

    Received on January 23, 2012, revised on August 11, 2012 and on October 24, 2012
    References: 17
    Availability Optimization for Coal Handling System using Genetic Algorithm
    2013, 9(1): 109-116.  doi:10.23940/ijpe.13.1.p109.mag
    Abstract    PDF (154KB)   
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    The paper deals with the availability optimization for Coal Handling System of a National Thermal Power Corporation (N.T.P.C.) Plant, using Genetic Algorithm (G.A.). Mathematical formulation is carried out using probabilistic approach and Markov birth – death process is used to develop the Chapman-Kolmogorov difference differential equations. These equations are further solved recursively in order to derive the Steady State Availability expression. The optimal values of availability of coal handling system have been evaluated using Matlab G.A. tool. The steady state availability obtained from Markov analysis is also compared with the optimal availability calculated through G.A.

    Received on January 12, 2012, revised on August 26, 2012 and September 22, 2012
    References: 09
    Short Communications
    Reliability of 1-out-of-(n+1) Warm Standby Systems Subject to Fault Level Coverage
    2013, 9(1): 117-120.  doi:10.23940/ijpe.13.1.p117.mag
    Abstract    PDF (92KB)   
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    Warm standby SParing (WSP) is a commonly-used fault tolerance technique that compromises the system energy consumption and recovery time. Imperfect fault coverage is an important factor that can restrict the reliability of a fault-tolerant system. In this paper, a generalized binary decision diagram (BDD)-based approach is presented to evaluate the reliability of a 1-out-of-(n+1) warm standby system subject to fault level coverage. Examples are presented to illustrate the application of the proposed method.

    Received on October 31, 2012, and revised on November 7, 2012
    References: 06
ISSN 0973-1318