Sharif Digital Repository

In this research, a scheduling problem, minimizing the sum of weighted earliness/tardiness in a flow shop sequence-dependent group scheduling (FSDGS) problem, is investigated. In this problem, every job has a distinct due date, early penalty rate, and tardy penalty rate. This problem is typically classified in the literature as F_m | fmls,S_plk,prmu | ∑(w_j^1 E_j+ w_j^2 T_j). A mixed integer linear programming model is developed for the proposed research problem. As the problem is proved to be strongly NP-hard, only small-size problems can be solved with the mathematical model. Thus, a metaheuristic algorithm based on the Particles Swarm Optimization (PSO) algorithm is developed to solve... 

This thesis studies a brachiation robot that is a long armed locomotion similar to apes. The robot has 2 revolute joints but only one of them is actuated. In this thesis, after deriving dynamic model of the robot, the Controlled Lagrangian (CL) method is used for stabilization. The matching conditions satisfied for the controller are derived and the extended λ-method is used to solve PDE’s involved in the method of controlled lagrangian. Satisfactory controller’s gains are chosen by PSO algorithm. Feasibility of the developed controller is investigated by numerical simulations and finally, theoretical results are validated with experimental observations  

The produced crude oil from the petroleum reservoirs usually has a value of brine (water and salt) this matter can be caused the corrosion of refinery equipment. The large part of this brine creates a stable emulsion with oil, that it couldn't be separated easily. For separation and demulsification of this emulsion, some chemical, mechanical, thermal and electrical methods can be executed. In chemical method, demulsifier materials can be added to water-in-oil emulsion. Different parameters such as properties of oil, type and concentration of demulsifiers, volume factor of water and etc., can affect the efficiency of water-in-oil emulsion separation. In this study, emulsification mechanism,... 

Determining the porosity, water saturation and permeability values in the reservoir rock, are major steps in the petroleum engineering and formation evaluation. Today in the oil industry, these parameters are obtained using Helium gas injection technique on core (Plug) samples. However, the coring operation is difficult and costly. In addition, there isn't the possibility of coring in some of wells, such as horizontal wells. In fact, the present research is the modelling of artificial neural networks to estimate permeability in one of the Iranian oil field reservoirs by using oil well logging data. In this research, MLP neural network has been used and for network training, the evolutionary... 

An important step in the early stages of an oilfield development is the accurate identification of the location of production and injection wells which has a significant impact on productivity and profitability of the reservoir. Recently, operation companies in petroleum industry focus on production optimization, recovery enhancement and cost reduction; as a result, application of non-conventional wells (NCW) or non-vertical wells have dramatically increased. Well placement optimization is a complicated task as it is a function of several contributing factors including reservoir heterogeneities and economic constraints. The complexity of this task increases when it is considered as a... 

Marine current power has been utilized in recent years as one of the most foreseeable renewable energy sources. In this study a multi-objective hydrofoil optimal design is carried out for use in marine current turbine in order to improve hydrodynamic performance due to low speed current in Qeshm channel. A particle swarm optimization code using FORTRAN is developed and coupled with XFoil software as flow solver that is based on panel method. B-spline curve is used to parameterize the hydrofoil shape and the coordinates values of the control points are designated to act as optimization parameters. Validity of flow solver examined by comparison made between computed data against experimental... 

Given many computing errors in current systems, a method appears necessary for predicting the nuclear parameter quickly and accurately. In this thesis, a neural network was used to predict safety in a nuclear power plant in order to develop an operating aid tool for preventive measures.First, some studies were conducted on appropriate feature selection for training neural networks. Some case studies have also been carried out on parameter prediction through soft computing in a power plant. In the next section, an expert judgment was taken into account to select DNBR (Departure from Nucleate Boiling Ratio) as a criterion for safety evaluation in the exploitation of a nuclear power plant (PWR)... 

In recent years passenger cars have been known as the main source of air pollution in urban areas. Despite all the research and efforts in minimizing the fuel consumption and emissions of internal combustion engines (ICE), this is merely a temporary solution. The permanent solution to overcome these disavantages is the use of electric vehicles (EV). The main downside of using electric vehicles is their short driving range. Multi-speed transmissions can be adopted to overcome this problem. Continuously variable transmissions (CVT) and infinitely variable transmissions (IVT) have been proven to enhance fuel economy in ICE vehicles and a great deal of research is being conducted to maximize... 

The traditional point of view on the scheduling of the healthcare systems, which is in common with the scheduling of other service and manufacturing systems, has contributed to inattention to patients’ psychological status and has given rise to many negative effects not only on them, but also on hospitals. However, this perspective has not been modified yet with respect to the features of healthcare systems, in which patients, rather that machines, are the main entities of the system. In this study, to address this draw back, a new concept, psyche-based optimization, as well as a new scheduling problem, anxiety-based scheduling of operating rooms, as the advent of this concept, have been... 

The most important sources in container terminals are berth and quay cranes. The main purpose in the container terminals is reducing delay times of vessels. This will be obtained with planning of terminal sources. This research addresses simultaneous berth and quay crane scheduling problem. A mixed integer linear mathematical model is proposed to minimize sum of completion time of vessels. Since the proposed research problem is NP-hard, two methahuristic algorithms based on Tabu Search (TS) and Particle Swarm Optimization (PSO) are presented to heuristically solve the problem. After parameter tuning, PSO and TS algorithms are compared with experimental design methods. The results indicate... 

In a solar central system plant about 40% of energy losses occurs in the heliostat field. Furtheremore, half of the investment costs for construction of the plant is related to the heliostat field. Therefore, an optimal design of the heliostat field is necessary for reduction of levelized cost of energy in solar tower power plants. In this study, in order to optimally design the heliostat field, first energy performance of the helistat field in one year is simulated. Solar power and sun’s position at each moment of the day is determined by mathematical relations. Then, loss factors in the field are modelled and heliostat field layout is designed by an algorithm. Finally, by using PSO... 

In the urban railway transportation system, large amount of power is consumed for starting the movement and acceleration. A great part of this energy is transformed to the train kinetic energy which in the case of break is reduced to zero. Thus recovering of train kinetic energy during the brake can help to reduce train energy consumption. One of the possible ways is using energy storage during the brake and using it again during acceleration. Storage can be performed in three kinds, fixed, mobile and hybrid. In this thesis, super capacitors have been investigated as fixed and mobile storages. After reviewing electrical railway transportation systems, elements of these systems have been... 

As the applications of wireless sensor networks are expanding at an increasing rate, design of these networks so that they conform to the requirements of a specific application is considered to be a major challenge. Regarding to the specific application, network designers consider various suitable parameters to improve and then to enhance the efficiency of the network. Parameters included are such as area coverage, lifetime, reliability and etc which can significantly improve with the precise placement of nodes. Node localization problem in wireless sensor networks aiming at improvement of the performance parameters has been solved by different methods. In this thesis, in order to solve this... 

The present thesis is focused upon the flow shop sequence dependent group scheduling problem (FSDGS) with no wait assumption. Generally, production sequencing and scheduling is considered as one of the most important factors in productivity and cost saving of organizations. Therefore, determining an appropriate sequencing of groups and jobs according to the logical constraints is expected to improve the performance and productivity of the production system.
In this thesis, due to the importance and multiple applications of this problem, we will consider the FSDGS problem and propose new heuristic and metaheuristic algorithms to tackle this problem. Since the good performance of... 

Image steganalysis is the technique and art of detecting covert communication via images.Reduction of features dimentionality is an important issue according to accuracy and time complexity. In this thesis, GA (genetic algorithm) and PSO (Particle Swarm Optimization) are used to reduce the dimentionality of JRM, a recently proposed feature set containing 11255 features which looks high dimentional compared to other feature sets which has been reduced by evolutionary algorithms so far. So, inspite of other works done using evolutionary algorithms in this field, we use the class sepearability criterion as fitness function instead of the accuracy of the classifier. Investigating these features,... 

Natural phenomena, such as earthquakes, floods, and hurricanes, have been, and will be, one major source of mankind disastrous problems. Mankindinterventions to relieve this heavy pressure on humanity have been divided into four categories: mitigation, preparedness, response, and recovery. This study is in the response phase, and aims to find an optimal network to help people in the devastated part of a city, hit by a major earthquake. Such earthquakes demolish buildings over the people inside, causing them fatal harm and serious injuries. At the same time, they ruin the city infrastructures (life lines), including transportation networks, preventing flow of relief supply to reach to the... 

Nowadays competition in business world has increased drastically. Under these competitive circumstances, it is the supply chains that compete against each other rather than individual firms. Accordingly trying to achieve integrated and synchronized management of activities within a supply chain has become inevitable. Recently researchers have found interest in a particular problem in a supply chain and that is to minimize inventory and routing costs in a supply chain. This problem is known as Inventory Routing Problem (IRP) and has been intensely examined in past few years. In this thesis we will try to expand this well-known problem in pricing dimension. We call this new problem “Inventory... 

Optimum highway alignment problem is among the most substantial but large and complicated topics in transportation area. Infinite number of feasible solutions, numerous local optima and the constrained feature of the problem, associated with complex and mainly non-linear constrains, has put an extra effort into the problem-solving process. Moreover, the problem has a sensitive objective function to input variables. Due to the nature of the problem, conventional methods fail to find any exact solution, and so, using heuristic methods during the solving procedure is inevitable. Large-scale, complexity and sensitivity of the problem leads to a solution which is time-consuming and...