Description:
This study concentrates on optimizing a multi-state weighted k-out-of-n system consisting of different types of reparable components. An optimization model is developed to decide upon both optimal redundancy allocation and best maintenance activities for reliability allocation. The optimization model is to maximize system reliability and minimize system cost simultaneously. To reach this goal, a financial view has been employed to estimate the system reliability, and combine it with system cost. The proposed model determines the number of each component type in the system, and the maintenance actions and the time at which they should be applied. Also, the model is programmed by MATLAB, and Genetic Algorithm is used to solve a practical case. (C) 2016 The Society of Manufacturing Engineers. Published by Elsevier Ltd. All rights reserved.
Description:
Shuffle-exchange networks (SENs) have been widely considered as practical interconnection systems due to their size of its switching elements (SEs) and uncomplicated configuration. SEN is a network among a large class of topologically equivalent multistage interconnection networks (MINs) that includes omega, indirect binary n-cube, baseline, and generalized cube. In this paper, SEN with additional stages that provide more redundant paths are analyzed. A common network topology with a 2×2 basic building block in a SEN and its variants in terms of extra-stages is investigated. As an illustration, three types of SENs are compared: SEN, SEN with an additional stage (SEN+), and SEN with two additional stages (SEN+2). Finally, three measures of reliability: terminal, broadcast, and network reliability for the three SEN systems are analyzed.
Description:
The purpose of this paper is to propose a modified version of Failure Mode and Effects Analysis (FMEA) to alleviate its drawbacks. FMEA is an important tool in risk evaluation and finding the priority of potential failure modes for corrective actions. In the proposed method, the Universal Generating Function (UGF) approach has been used to improve the assessment capability of the conventional Risk Priority Number (RPN) in ranking. The new method is named as URPN. It generates the most number of unique values in comparison with the previous methods and considers relative importance for the parameters while it is easy to compute. More unique numbers help to avoid from having the same priority level for different failure modes which represent various risk levels. A case study has been employed to demonstrate that the URPN not only can improve the shortcomings but also is able to provide accurate values for risk assessment. Copyright (c) 2015 John Wiley & Sons, Ltd.
Description:
In this paper, an implementation of lean manufacturing through learning curve modelling for labour forecast is discussed. First, various learning curve models are presented. Then the models are analyzed in terms of their advantages and limitations. As a case study, the learning curve modelling is presented with the data derived from a production company. With the application of the learning curve, labour need can be more accurately predicted and scheduled on time.
Description:
In this paper, an implementation of lean manufacturing through learning curve modelling for labour forecast is discussed. First, various learning curve models are presented. Then the models are analyzed in terms of their advantages and limitations. As a case study, the learning curve modelling is presented with the data derived from a production company. With the application of the learning curve, labour need can be more accurately predicted and scheduled on time.
Description:
Multistage Interconnection Networks (MINs) are network systems providing fast and efficient communications at a reasonable cost. A gamma network is a specific class of MINs, which provides redundant paths in the system. In a gamma network, information from source nodes is transmitted through a specific set of routes to destination nodes. Reliability of an MIN is used as a measure of system’s ability to transform information from input to output devices. Due to the complexity of network configuration and availability of redundant paths, reliability bounds to estimate the exact reliability of a gamma network is proposed. A numerical example of an 8 × 8 gamma network is presented to demonstrate the accuracy of the reliability bounds. When the lower bound reliability provides sufficient assurance that the system will be operational at some specified time and closely approximates the exact reliability, then no further effort for obtaining the exact reliability expression is necessary.
Description:
A new reliability evaluation methodology for multistate weighted k-out-of-n systems is presented in this article. The present value of the cash flow generated by the system components is used as a reliability value. We take a financial view of reliability and consider functioning periods and the time value of money in system reliability analysis. Two approaches, the universal generating function (UGF) and recursive algorithm, are applied to evaluate the reliability of the multistate weighted k-out-of-n system. An illustrative example is calculated based on the proposed system reliability evaluation methodology. It is shown that this evaluation method can also be used to find the value of the maintenance policy. Finally, the UGF and recursive algorithm approaches are compared with each other for large system reliability assessment. [ABSTRACT FROM AUTHOR] Copyright of Engineering Economist is the property of Taylor & Francis Ltd and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
Description:
An interconnection network system consists of layers of switching elements connected together in a predefined topology providing the connectivity between the set of processors and the set of memory modules. Performance analysis of a network system is important as it determines the usability and the efficiency of the network to provide services. A shuffle-exchange network (SEN), a specific type of Multistage Interconnection Network (MIN) that consists of 2x2 switching elements, has been widely considered as a practical interconnection system. This paper presents a network reliability model based on a minimum cut set method for SEN systems. A general equation for large-scale network reliability is derived subsequently to reduce the complexity of the reliability analysis for the interconnection network system. Read more: http://www.ijpe-online.com/p2-performance-analysis-of-a-multistage-interconnection-network-system-based-on-a-minimum-cut-set-method.html#ixzz34m0gTAiy
Description:
A challenging aspect of managing the development of complex projects is the notion of design iteration or rework. Traditional project management tools such as program evaluation and review technique (PERT), critical path method (CPM), and Gantt chart allow the modelling of sequential and parallel processes in projects, but they fail to address interdependency of feedback and iteration. Design structure matrix (DSM) is a new approach to project management, used to represent, analyse dependencies among tasks and show the order in which tasks are performed. In this paper, a case of the petroleum oil field development project is demonstrated. The project duration of the petroleum oil field development project is reduced significantly by applying the DSM method.
Description:
Improving the method for selecting risk-based competing improvement strategies has equal importance with failure risk quantification inthe FMEA methodology. Nevertheless, there are few studies which focus on this issue. Furthermore, the influence of factors relating to the businessenvironment which may support or derail improvement efforts is not considered in previous studies. In order to address these limitations, a model is proposed in which the impact of environmental factors is considered byintegrating SWOT analysis into the FMEA method in order to support the appraisal of competing risk-based improvement efforts. The impact of SWOTvariables is deployed using a decision support model based upon the benefit, cost, opportunity, risk and organisational readiness index (BCOR2) approach inorder for the FMEA team to select from competing corrective actions. A case example from industry is provided in which the proposed model is applied. This example illustrates that this new model contributes successfully to good practice by identifying the most appropriate corrective action option to take andimproves upon the decisions provided by existing developments of the FMEA methodology.
Description:
Flexible operation of post-combustion CO2 capture (PCC) plants can improve efficiency through coordinating the balance between consumer demands for electricity and CO2 emission reductions. This strategy however, will impose process disturbances while the PCC plant is ramped up, ramped down or turned off. This paper presents the preliminary development of a dynamic model for PCC in a brown coal-fired power plant using the process simulation software Aspen Plus Dynamics. Validation of the dynamic model will be against both steady state and dynamic data from the pilot plant. By gaining this understanding of the dynamic behavior, the technical and financial performance of PCC can be optimised.
Description:
Flexible operation of post-combustion CO2 capture (PCC) plants can improve efficiency through coordinating the balance between consumer demands for electricity and CO2 emission reductions. This strategy however, will impose process disturbances while the PCC plant is ramped up, ramped down or turned off. This paper presents the preliminary development of a dynamic model for PCC in a brown coal-fired power plant using the process simulation software Aspen Plus Dynamics. Validation of the dynamic model will be against both steady state and dynamic data from the pilot plant. By gaining this understanding of the dynamic behavior, the technical and financial performance of PCC can be optimised.
Description:
Automated material handling systems are usually characterised by robotic cells that result in the improvement of the production rate. The main purpose of this research is to study the scheduling of a rotationally arranged robotic cell with the multi-function robot (MFR). This special class of industrial robot is able not only to transfer the part between two adjacent processing stages but also to perform a special operation in transit. Considering MFR for material handling and operation, the objective function of the research here is the maximisation of production rate, or equivalently the minimization of the steady-state cycle time for identical part production. This problem is modelled as a travelling salesman problem to give computational benefits with respect to the existing solution methods. Then, the lower bound for the cycle time is deduced in order to measure the productivity gain of two practical production permutations, namely uphill and downhill permutations. As a design problem, a preliminary analysis initially identifies the regions where the productivity gain of a regular multi-function robotic cell is more than that of the corresponding single-function robotic cell for both small- and large-scale cells. The conclusion shows the suggested topics for future research.
Description:
Advantages of pre-cast technology in the construction of commercial, residential and institutional buildings are well documented in literature. However, the acceptance of this technology in Malaysia is relatively low with few projects being constructed with pre-cast components. The objectives of this paper are to measure labor productivity in construction, to examine productivity indicators between pre-cast and conventional Cast-In-Situ (CIS) methods, and to explore areas of improvements to promote adoption of precast technology in Malaysia. Data on construction labor productivity are collected using questionnaires, interviews, and observations at the construction sites. Based on statistical analysis performed in this paper, it is concluded that pre-cast method is better than conventional CIS method in terms of construction labor productivity, time to complete a project, variability of construction activities, and loss of efficiency during the construction process. Baseline productivity, unit rates for pre-cast components and correlation of the productivity factors to construction labor productivity are presented as well.