Sharif Digital Repository

Train timetabling is one of the most important problems in the railway scheduling field. It concerns with determining the trians’ arrival and departure times to/from each station so that some constraints are satisfied and some objectives are met. The objective in this thesis is to minimize the summation of dwell times of all trains. The timetables which are offered in this thesis are periodic. It means that each event repeats after a period time. The events are arrivals and departures of trains to/ from stations. In this timetable, the praying constraint is considered as wellso that after Azan time, the train has to dwell in the first station which has enough place for praying. So an integer... 

Reliability Centered maintenance (RCM) is a systematic approach for designing preventive maintenance program for plants. Quality Function Deployment (QFD), which is a well known tool of Total Quality Management, is also a systematic and disciplined approach for designing products and services. In QFD the objective is to satisfy the requirements of the customers of the product or service with limited resources. Now if we consider the preventive maintenance program that RCM specifies for a plant as a service and define the customer requirements for this service to be preserving the functions of the plant we can use QFD for maintenance via RCM. By doing this all the proven advantages of QFD... 

Schiff bases are used as prevalent ligands in coordination chemistry and are prepared easily. Their application as mild inhibitory agents for prevention of various steel’s corrosion in acidic solution has been proved. When their structure is altered, multi-purpose application for them is found. This property has led to a motive for research and study. In this study, electronic properties of a group of Schiff bases are investigated. The goal of this study is using quantum mechanics (QM) as a tool for specifying electronic properties of some of these bases. With respect to QM calculation which is done by density functional theory (DFT), their properties as inhibitory agents are studied. First,... 

The process of human populations growth, limited resources of fossil fuels and its environmental consequences have driven the international community to Renewable Energy. Microbial fuel cell (MFC) has ability of simultaneous wastewater treatment and electricity generation (Energy). This technology can be considered as one of the proposed solutions to reduce costs of wastewater treatment and power generation. Separators are one of the major components of the MFC that have direct impact on cell performance. On the other hand, high costs of the conventional types have caused to limiting development of the MFC in the last decade.
In this study, inexpensive and available glass wool membrane... 

Nitrate can be used as an oxidant in a cathode chamber of microbial fuel cell. Nitrate is known to be a pollutant of water particularly underground water and is considered a carcinogen of water. Nitrate was used in the cathode chamber of a microbial fuel cell as an oxidant that lead to simultaneous generation of electricity, removal of organic matter in anode, and removal of nitrate in the cathode. Using nitrate generated a voltage of 151 mV with an external resistance of 1000Ω. The maximum power density achieved was 1.375 mW/m2 with an external resistance of 800Ω. Seven days after the cell became operational and without the presence of a catalyst, the amount of COD had decreased by 25... 

Considering the wide range of applications of porous media for heat transfer enhancement in various components of industrial machineries, including solar collectors, air dryers, compact heat exchangers, electronic microchips, investigation of heat transfer characteristics in porous media has been a major concern for many researchers. On the other hand, precise understanding of the physics of porous media-flow interaction has been an open research topic for a long time. The present research however, has aimed at developing a computational method to simulate the interaction between fluid flow and porous media to investigate heat transfer from prously covered surfaces. Pore scale modeling of... 

Due date assignment for customer orders has been studied in various production environments. In this thesis a production system is considered in which the orders of several customers are produced in a single lot because of the economy of scale. If a lot is completed before receiving customer orders, inventory carrying cost is incurred. On shortages, a due date is quoted to customers and lead time quotation cost is incurred. The due date may not be met because of (lead-time) uncertainty in production system. Hence if the order is delivered after its due date, tardiness cost is charged. The literature reviews show that such a model is not considered by other researchers. Two different problems... 

A hierarchical production system in make-to-order environment is presented in this thesis. This production system is consisted of three different decision making levels. Maximum acceptance for production within customer specified time interval was done in the first stage, which is called order arriving stage, based on different client criteria, type of demanded product, and production system constraints. A new hierarchical decision making structure for accepting or rejecting arriving orders is proposed in this level. The output of this acceptance level is orders having maximum production system defined criteria, and minimum production cost along with order delivery time with minimum delay is... 

In recent years in assembly line balancing area many researchers have focused on identifying and modeling real world situations in assembly lines in order to obtain more suitable model. As a result many generalized models have been developed in assembly line balancing area. However, designing efficient algorithms to solve these generalized problems has just begun. In this study it is aimed to design efficient algorithms to solve one of these generalized problems. Specificcally two hybrid genetic algorithms (GA) are proposed to solve assembly line balancing problem with sequence dependent setup times. Scheduling of tasks in the stations has been less considered in the literature of assembly... 

In this thesis, a multi-stage project portfolio selection and scheduling problem in an uncertain environment is modeled, analyzed and solved. Moreover, we investigate the situations in which a project manager is confronted to a large number of projects to be selected and scheduled while the required resources of the projects are limited and renewable. The aim is to maximize objective function which is the net present value of the profit of the projects. To solve the mentioned problem, we introduce a multi-stage stochastic programming. For the reason that, in real problems, optimization problems that included all restraints are large scale and have computational complexity, these problems are... 

In the field of supply chain, management constantly seeks to adopt strategies for realizing its targeted objectives. The supply chain, therefore, includes integrated production-distribution processes with all effective parts where proper management requires a comprehensive and dynamic approach. It is necessary to meet required items at required time. This becomes more important with the supply systems providing items. On the other hand, the difficulty of supply chain management, decisions, and policy-making can be increased by a wide range of conditions such as changes in demand. Thus, a comprehensive approach is needed to take the present dynamics into account. The current paper develops a... 

Asset and liability management is a method for optimizing cash flows of input and output of a bank . The model for optimizing the balance between liability and assets of a bank is presented in this research. Bank asset liability management and planning can be considered at the same time. In tjis model , all assets and liabilities in the bank balance sheet are discussed under different objectives and requirements , such as legal and administrate requirements, market condition, risk rate etc  

Finding a proper and fair schedule for sport competitions has been an important issue, especially these days which professional sports has became a large scale business and profitability of sport competitions depends on the quality of the schedule.
Hence in the last three decades sport scheduling has been considered by computer science and operation research scientists.
Professional soccer league consists of many teams which compete in one round or double round robin tournament every year. In round robin tournaments each team has two matches, one at their own place and the other one at the competitors place. The main issues of the sport scheduling are the round and the host of...