Sharif Digital Repository

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... 

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... 

Traditionally, supplier selection should simultaneously take into account numerous heterogeneous criteria and then is a tedious task for the purchasing decision makers. The global supplier selection problem is more complex than domestic one and it needs more critical analysis. It becomes especially complicated when quantity discounts are considered at the same time. Under such manner, most studies often formulate such a problem as a Multi-Objective Linear Programming (MOLP) problem, and then scale it down to a Mixed Integer Programming (MIP) problem to handle the inherited multi-objectives simultaneously. However, this approach often neglects to consider scaling and subjective weighting... 

In electrification networks, a considerable percentage of electrical energy generated in power plant is dissipated through the path from generation to consumption, most of which is in electric power distribution, approximately 18%. The amount of these losses depends on several factors such as distribution networks structure, kind of apparatus, load density, kind of consumption, consumption curve, climatic conditions, due to diversity and variety of these factors, power losses differ even for two apparently similar electric power distribution . Power distribution companies in Iran decrease power losses since a few years ago, but in practice, because of different parameters and indexes, which... 

Many airlines operate different fleets under different service conditions. These aircraft fleets need to be maintained in service. Safety, reliability and economic reasons motivate manufacturers, airlines and airworthiness authorities to investigate about different approaches to aircraft maintenance. At first, corrective maintenance which was developed for other industries was used by the aircraft industry but due to increasing complexity of aircrafts and their systems the industry started using time based maintenance. After years of operation and fleet experience, this industry started developing a program of its own i.e., MSG-1, MSG-2 and MSG-3. These maintenance programs have been evolved... 

In this era, competition in economic fields is undeniable. According to huge amount of foreign trades between countries, economic prosperity of each country causes persuasion of foreign investors to come into that country for investment. Stock Exchanges is one sign of economic prosperity in each country, So prediction of the stock exchanges situation is very important. It is noteworthy that according to the importance of prediction in partial level, the necessity of predicting companies stock price is realized. According to the complicated term in this field, linear methods do not have appropriate efficiency for predicting, so nonlinear methods and especially Artificial Neural Networks are... 

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... 

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  

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... 

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... 

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... 

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... 

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... 

Due to the expansion of Industries, competition among manufactures is increasing. This increased competition includes increasing the number of competitors and the development of existing companies. In a competitive market, companies try to increase their market share and to maximize their profits by using different methods such as innovation in their products, pricing, marketing and other factors. In this study we introduce protein products market in Tehran and companies that compete in this market. Then we use an appropriate model to estimate the market share situation of Tehran meat products company (Solico). To find the market share situation, we need to know the effective characteristics... 

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... 

Construction projects in each country are considered as one of the main infrastructures for the growth and development of that country. Essentials and necessities to be able to extract the lowest cost with the highest quality. In this study, we aim to determine the optimal balance between cost and quality for construction projects by focusing on the theory of system reliability and the quantification of project quality. In the first stage, the whole construction project is considered as a system consisting of different work packages. In the second step, the reliability function is considered to calculate the quality performance and the nonlinear reliability-cost function is determined. In... 

Saffron has an important role in non-oil export in Iran. This product has different known and unknown attributes. In recent years Iran has spent great effort to declare this product to global markets. But, despite these efforts and while Iran is the greatest saffron producer in the world, the global markets is in authority of Spain and Iran has an unknown position in global markets. On the other hand lack of attention to systematic cultivation of Saffron leads to reduction quality levels, decreasing production rate and finally decreasing profitability in Iran. Also poor distribution and marketing and lack of full declaring Iranian saffron, internationally lose a large portion of global... 

In current societies, reliability is an important and fundamental factor in designing and manufacturing products and it cannot be ignored anyway; because sometimes malfunction and failure in a system can cause severe financial losses and health issues. In the field of optimizing reliability by redundancy allocation, one of the structures that has drawn many researchers attention is series-parallel structure. In the models proposed for reliability optimization in series-parallel systems, there is a restricting assumption which all components of a sub-system have to be homogeneous. In this thesis, new models are presented which enable components of a sub-system be non-homogeneous. Modeling is...