Sharif Digital Repository

Inherent safety means that the process is naturally safe and the conditions of occurrence of unsafe cases and situations are eliminated from the system so that unsafe conditions can be controlled and prevented from occurrence by means of layers of protection. In general, evaluation of inherent safety may be studied in two different conditions; the first one is associated with the units that are not completely designed and built yet. In the initial steps of developing a process, there is much freedom in the determination of materials, equipment, and designing variables. As soon as the process enters its life cycle, making changes in the process will be very difficult and expensive. Therefore,... 

System design, regardless of the type of system being considered, needs to determine parametersto maximize the system performance criteria.One of solutions of finding best system performance is using simulation optimization. In real world, end users have models with more than one objective and these objectives are conflicting objectives. There are a lot ofmeta-heuristic algorithms to solve multi-objective optimization problems. NSGA-II is one of the most popular proposed meta-heuristic algorithms to solve multi-objective problems. Because of using average to evaluate solutions, process of selecting new generations in this algorithm is such that in every generation some of suitable solutions... 

In recent years, due to environmental concerns together with rising costs of the fossil fuels, the wind energy usage in electricity generation of various countries has experienced a growing trend. Owing to inherent characteristics of wind turbines power generation, i.e. uncertainty in their output level as well as being undispatchable, the rapid growth of installed wind farms, however, has caused some new challenges in operation and planning studies of power systems. Among the major challenges in operation of high wind penetrated power systems, wind power curtailment has been emerged as a new problem in wind development. System operator may curtail wind farms output in order to meet system... 

Reservoir lifetime optimization is an important issue. The policies that are used for maximum production using optimization methods become challenging in the presence of uncertainty. Robust Optimization (RO) method is a technique to deal with uncertainty. Because of insufficient data, uncertainty is an inherent characteristic of reservoir model. This leads to inexact solutions of an optimization problem. Also, design based on uncertainty in economic parameters, especially uncertain oil price is a challenging issue. Taking the uncertainty explicitly is a solution when there is no measurement available. To take into account uncertainty several possible values (realizations) for the uncertainty... 

In the present study by subject optimal structure design of a polygeneration process, has been trying to obtain an optimal structure of a simultaneous production of methanol and power with the approach of green design based on economic and environmental criteria, discussed and examined. In fact, a new approach to green design solution removes environmental pollutants, not just the final refinement rather tried from the beginning to the process, which is designed to produce less pollution. This period coincides took the idea that design engineers concluded that in order to achieve an optimum design, putting together the correct process equipment is effective as design of the individual... 

Multi-objective optimization is an important branch of optimization. One of the most common methods to solve multi-objective problems is to find the Pareto efficient points. In practical applications, there are many instances in which there are no analytical formula for the function and only approximate values at some points are available. Derivative-free optimization is one approach to solve these problems.Here, we consider one of the multi-objective derivative-free optimization techniques called direct multisearch (DMS), recently proposed in the literature. In this method, a commonly used single objective optimization method is generalized to the multiobjective case. A popular category of... 

Motion planning in an autonomous vehicle is responsible for providing smooth, safe and efficient actions. Besides reducing the risk of collision with static and moving obstacles, the ability to make suitable decisionsencountering sudden changes in environment is very important. Many solutions for dealing this problem have been offered, one of which is, Artificial Potential Fields (APF). APF is a simple and computationally low cost method which keeps the robot away from the obstacles in the environment. However, this approach suffers from trapping in local minima’s of potential function and then fails to produce a plan. Furthermore,Oscillation in presence of obstacles or in narrow passages... 

Production scheduling is such a key issue that directly influences on the performance of the machines and efficiency of production line. This category of problems is to find simultaneously the lot sizes and their sequence over a finite set of planning periods.
In this Thesis a multi objective production planning and job shop scheduling problem is investigated. The objectives are minimization of the production cost and minimization of production time smoothness in consecutive periods. As the problem is shown to be NP-hard, two multi-objectives genetic algorithms with two approaches in selection of parents and crowding distance index are proposed to solve this problem. In these two meta... 

This work attempts to address the buffer allocation problem in an unreliable, linear production line. We try to determine the optimal sizes of buffers between adjacent work stations in such a way that a measure of costs is minimized and the production rate is simultaneously maximized. We resort to simulation optimization in order to determine the best combination of input parameters that leads to a near optimal performance for the system. To achieve this purpose, we employ a multi-objective genetic algorithm (NSGAII) in the optimization phase along with simulation as the tool for evaluating the objective function. To determine the merits of the proposed method, we compare the performance of... 

Axial compressors are utilized to increase compressible flow pressure in an efficient manner where mass flow rate is high, such as aviation engines and power generation gas turbines. The flow is compressed within this machine through several stages. Each stage consists of a rotor blade row followed by a stator blade row. Energy transfer to the air is performed on the rotor by changing its velocity vector. Then, pressure is recovered from velocity by diffusion, meanwhile turning the flow direction through stator blades. These blades have been designed and optimized with various methods evolved with developing computational and manufacturing facilities. In this thesis the aerodynamic design of... 

One of the challenges of today's economy, is improving economic structures and reduce its dependence on oil revenues. Agricultural industry as an important part of the economy, is not dependent on oil revenues and improving its structure can have a significant impact on increasing revenues. Kerman province with a high proportion of horticultural products in the country, plays a significant role in Agricultural industry .However, the problem of water shortages in the country, highlighted the efficient use of water in economic purpose and crop-planning. By the problems with the current structure, lack of management of planting crops, lack of proper supply chain, redesign of agricultural supply... 

Increasing the fuel cost and concerns about pollutions have facilitated the use of renewable energies. Wind power as a renewable energy has been considered as a good representative for conventional resources of electrical energy. The biggest obstacles for efficient use of the wind energy are changeability and uncontrollability in wind farm generation and to be far from the demand center. Also, conventional approaches cannot be applied to analyze the effects of this energy on power system. With increment in the penetration of the wind energy in power system, the necessity of considering its effects, especially large scale wind farm, in transmission expansion planning (TEP) studies is... 

This study presents a multi-objective optimization framework for transmission expansion planning in restructured electricity markets under uncertainty considerations. Deregulation of power system has introduced new objectives and requirements for transmission expansion planning problem. Also, the unbundling of electricity industry introduced new uncertainties and escalated the existing ones in network planning. Under these circumstances there is an emerging need for new planning models to cope with restructured electricity industry requirements.The conventional least-cost approaches which represent the transmission expansion planning as a single objective optimization problem could not... 

Optimization methodologies with an emphasis on turbomachinery applications are of great interest. In the present study, a framework is proposed for the multi-objective optimization of a compressor blade using a coupled approximator and optimizer modules, as a mean for lowering the vast computational costs. The proposed framework consists of three main units: a CFD solver, an approximator unit, and an optimizer module. In this regard, a multi-layer perceptron artificial neural network is used as the approximator module while a multi-objective genetic algorithm, the non-dominated sorting genetic algorithm-NSGA II, is employed as the optimizer unit of the framework. In addition, a commercial... 

A common decision in project management is the selection of contractors to simultaneously optimize three objectives of the project’s triangle. This issue becomes more important if there is more monetary value involved or there is limited number of capable contractors. In project planning, there is numerous choices for tasks; each with specific time, cost and quality. There is no trade-off problem, if one of the choices has the best time, cost, and quality, simultaneously. However, as these criteria do not generally work in a unique direction, it makes the selection decision difficult. A contractor who performs the projects on time may have higher cost and lower quality. Given that there is a... 

In this project, process of conceptual design and design optimization is presented for a cloud seeding UAV. Inefficiency of classical and statical design approaches is more obvious in new designed missions restricted to different and numerous Dynamic and performance constraints with no similar design target aircraft. So in this project we used conceptual design optimization approach with respect to aerodynamic, weight and balance, performance and stability discipline to overcome those restrictions and to design a cloud seeding UAV. In order to reduce the computational time, we used low fidelity method (analectic equation) in performance and stability, medium fidelity method (empherical... 

Power distribution network planning and related optimization is an interesting research subject and many papers have been published on this topic. Distribution network planning started in developed countries. Therefore network models are based on reliable network data, educated crew and low interest rate. Nowadays, Iranian engineers and researches try to use their research result for solving network optimization problems but sometimes the result of optimization is not achievable in reality. In current thesis, modeling approaches developed by previous researchers were compared and the effect of model simplification was evaluated. This evaluation was based on data gathered from local power... 

To reduce construction costs selecting the optimal route for water conveyance line entails ample observation and considering all effective parameters. Some part of Aidoghmoush dam project of water conveyance line located in Azerbijan the east has been investigated in this research. First, by investigating, effective factors in determining the optimal route have been identified and then categorized into two groups of quantitative criteria(technical-economical) and qualitative criteria(environmental). Quantitative objectives include: slope, transportation system, infrastructures, fault and soil type. Qualitative objectives include: environmental considerations, land use and land cover. Because... 

Nowadays, by development of technology and population, rivers have been faced environmental issues. In one hand, due to the several factors that can affect rivers pollution, it is not easy to propose a comprehensive solution for the above mentioned issues, while, on the other hand, it is necessary to address and resolve some of these issues as soon as possible. Considering rives as a system, there are lots of economic, political and quite a few other factors which try to change the condition to their own interest. In order to find a solution that satisfies all the effective parameters up to a certain limit, a mathematical tool, called the Game theory method, is utilized. In this research, we... 

In this thesis attempted to present practical hydro-aerodynanic model with low computational time and high accuracy for WIG craft with a compound wing, a catamaran hull form and a power augmented ram (PAR) platform at take-off phase. To achieve this innovation, aerodynamic and hudrodynamic model are coupled and dynamic air cushion between demi hull of catamaran under the wing was considered by modeling PAR platform with effect of flap. To validaty the results of hydro-aerodynanic model, two test models were producted and the results of hydro-aerodynanic model are compared with the experimental results that the presented results had good agreement with the experimental results. Influence of...