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  • Original articles
    Evaluating Communication-Network Reliability with Heterogeneous Link-Capacities Using Subset Enumeration
    2006, 2(1): 3-17.  doi:10.23940/ijpe.06.1.p3.mag
    Abstract    PDF (360KB)   
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    This paper proposes an improved algorithm to compute the reliability of a communication-network having heterogeneous link capacities. The reliability measure, capacity related reliability (CRR), is a generalization of a two-terminal reliability. A subset-cut-technique (SCT [7]) obtains CRR in two steps. First, SCT generates non-redundant subset-cut (SC) of the evaluated network. Second, the technique uses a sum-of-disjoint product algorithm to compute CRR from the generated SC. The computational complexity of SCT depends on the total number of subsets generated, the total number of internal (external) redundant SC generated and removed, and the total number of cuts in the network that are used to generate SC. The SCT generates too many subsets and internal (external)-redundant SC. In this paper, we propose a new subset cut enumeration (SCE) technique, which significantly reduces the total number of enumerated subsets and the total number of internal-redundant SC. Hence, the non-redundant SC are generated more efficiently. Examples are given to illustrate the technique, and the time complexity of our SCE is also described. Our method has been implemented in C and results show that SCE performs better than SCT.
    Received on March 1, 2005
    References: 12

    Nonparametric Estimation of Performance and Performability for Semi-Markov Processes
    2006, 2(1): 19-27.  doi:10.23940/ijpe.06.1.p19.mag
    Abstract    PDF (256KB)   
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    In this paper a nonparametric estimator of the performability for semi-Markov systems is proposed. It is proven that this estimator is strongly consistent and asymptotic normal. A numerical example of a three state semi-Markov system is also presented.
    Received on February 2, 2005

    Survivability Quantification: The Analytical Modeling Approach
    2006, 2(1): 29-44.  doi:10.23940/ijpe.06.1.p29.mag
    Abstract    PDF (307KB)   
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    In this paper, we present a general survivability quantification approach that is applicable to a wide range of system architectures, applications, failure/recovery behaviors, and metrics. We show how this approach can be applied to derive survivability measures based on the current definition and extend it to other measures that are not covered by any current definition but can provide helpful information for better understanding of system steady state and transient behavior under various adverse conditions. An example of a telecommunications switching system is given for the purpose of illustration. Markov models are developed and solved for the example to show the use of the proposed quantification approach via analytical modeling.
    Received on March 1, 2005
    References: 33

    Performability: Pedagogical Perspectives
    2006, 2(1): 61-74.  doi:10.23940/ijpe.06.1.p61.mag
    Abstract    PDF (244KB)   
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    Links of performability to environmental health and safety are developed through policy and legal pressures as well as through illustrations from some major disasters. The human factors inherent in performability can be addressed in part though education and training, and distance teaching has an important role to play. Approaches to providing this education are outlined together with some measures of performance.
    Received on March 21, 2005
    References: 16

    Sustainable Development and Environmental Assessment: A Case Study of a Fertilizer Project
    2006, 2(1): 76-87.  doi:10.23940/ijpe.06.1.p76.mag
    Abstract    PDF (106KB)   
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    Environmental assessment (EA) in principle is adopted to ensure that gains from developmental projects are sustainable and that such projects do not irreversibly damage ecological environment. The concept of sustainability would take into account conservation, alternatives, and protection of natural resources when considering developmental projects. The environmental assessment and review process for a nitrogen fertilizer plant was examined as a case study to determine deficiencies and limitations of the existing environmental process. A preliminary analysis showed the benefit of integrating the concept of sustainable development into the environmental assessment process as it relates to agricultural practices in the province and fertilizer production.
    Received on January 16, 2005
    References: 28

    Enduring Quality: A Key Factor to Increase Resource Productivity
    2006, 2(1): 89-97.  doi:10.23940/ijpe.06.1.p89.mag
    Abstract    PDF (88KB)   
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    The currently low utilization rate of products is mainly a result of their qualitative properties, of market needs (fast replacement) and of consumer behaviour. Indeed, products are now specifically designed and produced to be quickly replaced, so that manufacturers can maintain high production volumes; however, this trend leads to resource depletion and environmental imbalances. In order to substantially increase resource productivity (by at least 10 times), the technical and economic features of goods have to be radically changed so that their use may be optimized. This could be done through the concept of enduring quality, based on functions – rather than properties - characterized by long-term stability. Of course, a significant change of this kind would involve a radical modification of all production trends and of our basic understanding of goods. At the same time, we also need to change the way we utilize goods. The aim of this paper is to highlight this paradigm in order to identify which are the main factors able to get enduring quality to maximize the utilization rate of durables and, consequently, to increase resource productivity.
    Received on January 4, 2005
    References: 36

ISSN 0973-1318