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A New Model in Order to Determine Maintenance Strategy for Series-parallel Systems
, M.Sc. Thesis Sharif University of Technology ; Eshraghnia Jahromi, Abdolhamid (Supervisor)
Abstract
Reliability in today's world plays a pivotal role. As technology makes progress in various industries such as aviation and defense, the need for high reliability of systems is felt more and more. In this regard, reliability is directly related to the lives of people, and its high level can play a significant role in the profitability of organizations. Selective Maintenance, as one of the research areas in the field of reliability optimization, strives to enhance the reliability of the system and minimize the costs of the system by finding optimal maintenance policy. In the models that have been presented to optimize the selective maintenance policy, the assumption that the repair cost of...
Reliability Analysis of Tehran Bus Rapid Transit Line 1 and Presentation of Preventive Maintenance for Reduction of Failures
, M.Sc. Thesis Sharif University of Technology ; Eshraghnia Jahromi, Abdolhamid (Supervisor)
Abstract
Reliability and availability are one of the sensitive and significant points in each maintenance system. Due to the nature of bus system failures, that almost consist of large percentage of possibility risk factors is the systems maintenance, in this study for implementing our proposed model, the bus rapid transit garage-line1 were selected. This model is to provide solutions in strategic and operational levels in the network's garage in several sessions. The solutions include decisions about the capacity of human resources in the workshop system, determine the communication policies with suppliers of spare parts and human resources training policies by the standard scoring system, the...
Reliabilty Optimization of a Nonrepairable k out of n System with Composition of Warm and Cold Standby Components and Consideration of Switching
, M.Sc. Thesis Sharif University of Technology ; Eshraghnia Jahromi, Abdolhamid (Supervisor)
Abstract
Due to reliability importance in military and industrial sectors, increasing of reliability is inevitable. One of the most important ways to increase the reliability of a system is to use cold and warm standby components. In this thesis, the analysed system is a nonrepairable k out of n system consist of hot, warm and cold components. Considering the importance of switch operation in this system the imapcts of switches on the overall system reliability has been analysed. The behavior of components and switches oby exponential distribution. The hazard rate for hot, warm and cold components is shown respectively by, and. Also the hazard rate of switch for cold to warm is shown by and for...
Identifying and Ranking Supply Chain Risk Factors and Calculating Reliability in 3 Level Supply Chain
, M.Sc. Thesis Sharif University of Technology ; Eshraghnia Jahromi, Abdolhamid (Supervisor)
Abstract
Since 1990, supply chains get affected by business environment changes and become more vulnerable. Changes such as globalization, decrease of inventory levels, out sourcing, etc. in this thesis after reviewing some paper, researches are categorized in 8 group. Then 30 risk factor identified from this papers. Because of basic differences in industries and different importance of risk factors in them, a case was studied in one industrial area and risk factors was evaluated in a two-step evaluation. Eventually some advices presented for increasing reliability for that case
Replacement-repair policy based on a simulation model for multi-state deteriorating products under warranty
, Article Scientia Iranica ; Volume 16, Issue 1 E , 2009 , Pages 26-35 ; 10263098 (ISSN) ; Vahdani, H ; Sharif University of Technology
2009
Abstract
In this paper, a replacement-repair model is developed to study a warranty servicing policy for a class of multi-state deteriorating and repairable products, based on a computer simulation analysis. In each working state there is a determined probability for transition to each of the subsequent states, given that it has made a transition out of that state. There are two parameters that determine the manufacturer's decision to repair or replace a failed item, assuming that the buyer's claim is valid; the deterioration degree of the item and the length of the residual warranty period. Beside these two parameters, other inputs to the model are: the number of working and failure states, the...
Warranty servicing for special class of multi-state deteriorating products under renewing free-replacement warranty
, Article 40th International Conference on Computers and Industrial Engineering: Soft Computing Techniques for Advanced Manufacturing and Service Systems, CIE40 2010, 25 July 2010 through 28 July 2010 ; 2010 ; 9781424472956 (ISBN) ; Mahlooji, H ; Eshraghnia Jahromi, A ; Sharif University of Technology
2010
Abstract
We develop a replacement-repair model to study a renewing free replacement warranty (RFRW) for a class of multi-state deteriorating repairable products. Each product may experience N different working states with different hazard functions, before the warranty contract expires. Once the item enters working state j(j = 1, 2, . . . , N), it can either fail or move t any of the subsequent states. In the former case, the best rectification action, replacement or minimal repair, regarding the failure status, should be done to put the item into operation. In each working state there is a determined probability for transition to each of the subsequent working states. After a replacement the product...
Fuzzy reliability optimization models for redundant systems [electronic resource]
, Article International Journal of Industrial engineering ; July 2008, Vol. 4, No. 7, 1-9 ; Eshghi, Kourosh ; Eshraghniaye Jahromi, Abdolhamid ; Sharif University of Technology
Abstract
In this paper, a special class of redundancy optimization problem with fuzzy random variables is presented. In this model, fuzzy random lifetimes are considered as basic parameters and the Er-expected of system lifetime is used as a major type of system performance. Then a redundancy optimization problem is formulated as a binary integer programming model. Furthermore, illustrative numerical examples are also given to clarify the methods discussed in this paper
Shared information in a serial inventory system [electronic resource]
, Article International Journal of Advanced Operations Management - IJAOM ; 2011 Vol.3, No.2 pp.101 - 121 ; Eshraghniaye Jahromi, Abdolhamid ; Eshghi, Kourosh ; Sharif University of Technology
Abstract
In this study, a supply chain model consisting of a single product, one supplier and one retailer is considered. Transportation times are constant and demands at the retailer are assumed to be generated by a stationary Poisson process. Demands not covered immediately from inventory are backordered. The retailer carries inventory and replenishes stock according to a (Q, R) policy. The supplier has online information about the demand at the retailer and uses this information to replenish its stock. The order size at the supplier is a multiple integer to the retailer's order size. Considering order costs for the retailer and the supplier, we derive the exact cost function for this inventory...
A resource constrained project scheduling problem with fuzzy random duration [electronic resource]
, Article Journal of Uncertain Systems ; Vol.4, No.2, pp.123-132, 2010 ; Eshghi, Kourosh ; Eshragh Jahromi, Abdolhamid ; Sharif University of Technology
Abstract
In this paper, first a fuzzy random resource-constrained project scheduling problem is presented. The object of the problem is to find the optimal scheduling of project activities. In this model, duration of project activities is a fuzzy random variable. Then, the proposed model is formulated by using the expected value of fuzzy random variables as an IP model. An illustrative example is also provided to clarify the concept. © 2010 World Academic Press, UK. All rights reserved
Estimation of Three Parameters of Weibull Distribution Using Tabu Search Method: Implementation in Maintenance Program
, M.Sc. Thesis Sharif University of Technology ; Eshraghniaye Jahromi, Abdolhamid (Supervisor)
Abstract
Knowing the shape and type of the breakdown of a system or the system components, for a maintenance manager or maintenance engineer is significantly important. It is also important that the existing information concerning the system performance predict and prevent a sudden failure to be probably taken place. Maintenance has gained in importance as a support function for ensuring equipment availability, quality products, on-time deliveries, and plant safety. Cost effectiveness and accuracy are two basic criteria for good maintenance. Many studies in the area of equipment maintenance, replacement, and reliability require that the failure characteristic of a component to be estimated from...
A Model for Reducing the Cost of Organization with the Use of Process Attitude (Along with a Case Study)
, M.Sc. Thesis Sharif University of Technology ; Eshraghniaye Jahromi, Abdolhamid (Supervisor)
Abstract
Undoubtedly, reducing the organization's costs in today's world economy situation is a requisite for the survival of the organization. In order to continue their economic life, organizations must make their movements more effective by reducing costs and increasing agility and productivity. Various methods have been proposed to reduce costs, but before any measurements, identification of the reducible factors is very necessary.
Improving processes in an organization is considered as one of the best ways to reduce costs and increase profitability. In this research, the goal is to provide a model for reducing costs using process attitude so that the associated costs of the organization can...
Improving processes in an organization is considered as one of the best ways to reduce costs and increase profitability. In this research, the goal is to provide a model for reducing costs using process attitude so that the associated costs of the organization can...
Presentation of Applicable Linear Program Model for Reverse Logistics
, M.Sc. Thesis Sharif University of Technology ; Eshraghniaye Jahromi, Abdolhamid (Supervisor)
Abstract
We probably can say all people that are familiar with industrial engineering, have some information about supply chain management. Of course some people have more information about it and some have less. However, it is expected that they have some information about logistics because logistics is one of the most important elements in supply chain management. But it is sure that they have no information or less information about reverse logistics. That is why I have chosen this subject as my thesis. I have presented an optimization model with a numerical example
Offering a New Method to Determine Failure Rate of a System's Subsystems
, M.Sc. Thesis Sharif University of Technology ; Eshraghniaye Jahromi, Abdolhamid (Supervisor)
Abstract
Determining the failure rate or reliability of a system's subsystems, is an important and influential stage which is noteworthy not only in design and in manufacture phases but also in improvement phase. This process is called reliability allocation in literature. Reliability allocation guarantees more reliable and competitive product. The consequence of considering this phase in designing a product is to improve designing and manufacturing methods. As a result, it is possible to gain cheap and reliable product while is compatible with costumer's demands. Many factors and parameters which exist in the process of reliability allocation, have caused it to complicated process. A number of...
Provide a Comprehensive Model to Select the Appropriate Mode and Method of Technology Acquisition, Using Analytic Network Process
, M.Sc. Thesis Sharif University of Technology ; Eshraghniaye Jahromi, Abdolhamid (Supervisor)
Abstract
Selection of appropriate acquisition mode for a required technology is one of the critical strategic decisions in formulating a technology strategy. Although a number of factors were found to be influential in the choice of technology acquisition mode, it still remains a void in the literature how to make a strategic decision, based on a huge set of those factors with the help of a systematic approach. This study deals with the selection of technology acquisition mode & method as a multiple criteria decision making (MCDM) problem. It tries to provide more appropriate solution for prioritizing technology acquisition modes through analytic network process (ANP), along with considering internal...
The Effect Of Economic Factors On Tehran Stock Exchange
, M.Sc. Thesis Sharif University of Technology ; Eshraghniaye Jahromi, Abdolhamid (Supervisor)
Abstract
In this study it is attempted to investigate the impact of macroeconomic variables on the determination stock price in Iran.In this study it is used quarterly time series data of stock price and also macroeconomic variables including Growth of Consumer Price Index(Inflation), Iran Crude Oil Price, Exchange Rate, Gold Price, Liquidity, Money Supply and Gross Domestic Product for a period of 10 years (1381:1-1390:4). Data is obtained from monthly and quarterly reports, available on the website of the Central Bank of Iran and Tehran Stock Exchange Organization. In the analysis of the collected data, It is applied unit root tests, test for co integration, and utilize a Vector Auto Regressive...
Quantitative Risk Assessment on Water Conduits by Regression Model and Its Application in Predicting the Cost of Repairing and Replacing
, M.Sc. Thesis Sharif University of Technology ; Eshraghniaye Jahromi, Abdolhamid (Supervisor)
Abstract
Since early civilizations underground water pipes have played a major role on promoting human being life style. Today, centuries after designing water mains equipment, utilizing a water distribution and sewage collection system is matter of great necessity in modern metropolises. In current research the pilot area is located in the city center .the major motivation for opting such area was extraordinary breakage rate which was unseen on other city areas and nearby cities. Data pertaining to four commonly used pipe material were collected. Preliminary data quality analysis was conducted to detect distinct contradictions. On basis of collected data, breakage rate plots were depicted for each...
Preventive Replacement in Systems with two Dependent Components
, M.Sc. Thesis Sharif University of Technology ; Eshraghniaye Jahromi, Abdolhamid (Supervisor)
Abstract
In the last few decades due to technological progress and more attention to cost reduction of production, production systems have become more automated than before. By increasing the role of machines in manufacturing systems maintenance systems have become more important. One of the factors that influence the complexity of maintenance problem in real world is the interdependency of components in a system. Interacting cooperation between these components intensifies the complexity of the problem’s modeling as well as its optimizing. This complexity result in few studies that have been performed in this field. Thus these works can be broken into two main subjects. In the first case a system...
Comparative Evaluation of High Speed Railway Productivity in Different Regions and Recommendation of a Domestic Strategy for Iran
, M.Sc. Thesis Sharif University of Technology ; Eshraghnya Jahromi, Abdolhamid (Supervisor)
Abstract
This thesis presents the comparative evaluation of high speed railway productivity in different countries and recommends a domestic strategy for Iran. The main goal of the research is the comparative evaluation of the productivity and efficiency in the high-speed railway systems of different countries, using multi objective decision-making process and data envelopment analysis. Finally, the result of analysis shows that, Japan, China, France and Spain have consequently obtained the best efficiency of high speed railway.
After that, Japan high speed railway system is evaluating and analyzing of productivity in its life cycle. The last part of the research establishes an approach to find...
After that, Japan high speed railway system is evaluating and analyzing of productivity in its life cycle. The last part of the research establishes an approach to find...
Human Reliability and Risk Analysis Based on Fuzzy Inference and PROMETHEE
, M.Sc. Thesis Sharif University of Technology ; Eshraghniaye Jahromi, Abdolhamid (Supervisor)
Abstract
In the complicated industrial world interactions between human and machine always result in the higher human risk. Moreover, human may act differently in same situations on the basis of iner conflict, complexity or diverse motivations. Therefore, investigating human reliability is really more complicated than reliability of some mechanic parts of the system.within this study, human reliability factors have been intensively explored and based on Mamdani Fuzzy Inference and PROMETHEE these factors ranked for numerical example. Using this method, one may benefit its dynamic adaptivity and also its ability to contain eperts knowlegde within the Fuzzy Role Base. Furhtermore, Validity of the...
Modeling a Healthcare System Using Simulation-based Queuing Theory
, M.Sc. Thesis Sharif University of Technology ; Eshraghniaye Jahromi, Abdolhamid (Supervisor)
Abstract
Healthcare industry, in terms of gross national product, is one of the largest and fastest growing sectors of almost all countries. It is not surprising that a large amount of research has been focused on advancing medical practices and improving management methods in healthcare systems. One of the most important areas for improvement is patient flow management. Patient flow indicates the capability of a health care system in providing fast, reliable, and efficient services. Although capacity of health care system has grown, patients still have been facing long delays before getting into the system due to ineffective management. Queuing models can offer appropriate methods for analyzing and...