Sharif Digital Repository

The inlet duct is one of the most important components of the waterjet propulsion system, whose hydrodynamic performance is directly related to the capabilities and efficiency of the waterjet propulsion system. In this study, a procedure was proposed to improve the hydrodynamic performance of an inlet duct. According to this proposed procedure, first the basic intake duct geometry of the waterjet propulsion system was prepared using visual programming to simplify the repetition of the design in Rhino design software, and then the numerical analysis of the designed geometry in Star CCM+ commercial software was performed. The simulation results were validated with the results of an... 

Technological progress, complexity in costumers’ needs and distributed resources make extreme competition in business environment. It produces some novel concepts. In this research, we concentrate on cloud manufacturing which was generated by using cloud computing concepts and focuses on resources sharing between various manufacturers. One of key problems in this field is service composition. In this work, I have proposed a mathematical model with binary variables for service composition problem in multi-cloud manufacturing environment. In this model, I’ve considered for qualities of services (cost, time, energy, reliability) as objective functions. Cost and time functions include the cost... 

One of the primary concerns on many traditional capacitated facility location-network design problems is to consider costs of transportation and establishing of facilities in one single objective function. Considering a single objective in these problems may lead to misleading solutions due to the fact that the transportation costs should be considered in a short-term period of time, and therefore, the higher cost of establishing the facilities may unfairly dilute the role of the transportation cost. In this thesis, we introduce the capacitated facility location-network design problem with two separate objective functions. Moreover, in this problem, it is assumed that for connecting two... 

Tolerance allocation in the recent mechanical assembly is significant because it straightly affects product performance and cost. Loose tolerances may cause the quality defect while tight tolerances can increase the cost. Thermal effects and the temperature gradients are one of the factors that caused changes in the size and geometry of the components during the performance of mechanical assemblies. This thesis proposes a new approach for tolerance design considering the thermal effects, to achieve lower manufacturing cost and good product quality. Finite element analysis is used to determine the deformation of components in an assembly. The neural network is trained using experimental... 

This research solves a Location-Routing model based on the data of Tejarat bank branches in Tehran. The goal of the model is to minimize the cost of building & operating bank treasuries, optimize the cost of money transferring to branches of the bank & reduce the stealing risk. Because of the wide range of definitions for risk, time parameter is used as risk factor for its importance in bank money car stealing. Non-dominated Sorting Genetic Algorithm which is a common algorithm in multi-objective optimization literature with big data, is used to solve the proposed model  

Prostate cancer is the second most common cancer in men and the fourth most common cancer in all cancers. Cancer treatment is done according to the type of cancer and its diagnosis stage with different treatment methods and plans. Brachytherapy is one of the most common methods of cancer treatment along with teletherapy, surgery and chemotherapy. In this method, the source of radiation is located near or inside the tumor, and its advantage is to achieve a lower dose ratio of healthy tissue to the tumor is lower compared to teletherapy. One of the challenges in brachytherapy is to prescribe the appropriate treatment plan for the patient, so that the maximum dose of sources reaches the... 

In this thesis, the process of laser assisted machining (LAM) of metal matrix composites (MMC) is experimentally studied. The effects of process parameters (cutting speed, feed rate and depth of cut), laser parameters (laser power, laser frequency and laser beam angle), and the percentage of reinforcing particles on the tool wear and the surface roughness are investigated. Furthermore, the effects of these parameters on the built-up edge (BUE), chip shape, and workpiece temperature are explored.The experiments were performed using uncoated tungsten carbide and PCD tools under dry conditions. In order to analyze the sensitivity of the process parameters, the Plackett-Burman method was used... 

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... 

This thesis studies a probabilistic bi-objective location-routing problem that considers multi-product, multi-period system with direct shipment and split delivery which is a case study in SAIPA Group. This model also considers location, allocation and routing decisions in three-level supply chain including factories, distribution centers and customers. Each product for each DC can be supplied by more than one supplier in each period of time, and each factory has a limited capacity. As shortage isn’t allowable, all of the customer’s demand should be satisfied in each period of time. Since customer’s demand could be more than vehicle’s capacity, each customer could be visited more than once... 

The multi-facility location-allocation problem is concerned with locating m facilities in the Euclidian plane and allocating n customers to them at minimum total cost. In this work, we focus on a probabilistic version of the problem, in which the locations of the customers and their arrivals are probabilistically distributed. We first formulate the problem as a continuous location-allocation problem. Then, we give an approximated discrete model in which facilities can be located on a set of candidate points. The proposed model has two objective functions which can be calculated only through simulation. Considering the NP-hard nature of the problem and the functions’ unique properties, we use... 

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... 

Most construction projects contain activities repeated in project units or locations with definite consequence. These kinds of projects are called repetitive projects. One of the fundamental objectives of planning and scheduling of repetitive projects is using resources optimally and without interruption, a concept known as continuous workflow. Traditional planning and scheduling methods like Critical Path Method (CPM) are criticized for their disability to produce a reliable workflow. Ignoring the concept of workflow in project schedule causes time and cost overrun that arise from additional waiting times and also increase the risk of accessibility to resources on time. Therefore in this... 

Portfolio selection is a major problem in organizations and plays an important role in meeting the strategic objectives of organizations. For this aim, the management of the organization has to take into account many constraints in selection of projects in order to make an acceptable decision. Investment Budget is one of these constraints. On the other hand, in many cases the management of organizations must consider many decision criteria. These criteria always have conflict among each other and the decision maker try to tradeoff among them. This decision making requires exact and sufficient information for the decision maker to make a correct decision. The need for sufficient information... 

Today, oscillating heat pipes play an undeniable role in energy recovery due to their high thermal capacity. Studies show that the working fluid plays a more effective role in improving the performance of the oscillating heat pipes. In this study, a model is proposed to determine the optimal concentrations of Fe3O4-MWCNT/DI Water hybrid nanofluid based on NSGA-II multi-objective optimization algorithm. The Thermophysical properties of the fluid have been optimized to obtain the concentrations that provide the highest thermal conductivity and specific heat capacity and the lowest dynamic viscosity and density for hybrid nanofluids. Then a number of these concentrations¬ have ¬been selected... 

This thesis proposes a new non-linear multi-objective Location-Inventory-Routing problem (LIRP( for perishable products considering multi trips for vehicles. Managing the expiration date of perishable products, speed of vehicles in the system, the frequency of using the vehicles and etc. bring complexity in LIRP in this problem.
First objective focuses on maximizing profits calculated by Incomes of selling goods with different worthwhile depend on their remained life time and costs of inventory and distribution as well as ordering. Minimizing CO_2 emmition as the environmental issue has been considered as the second objective. Third objective which is minimization of injury rate,... 

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... 

Today, the additive manufacturing process is one of the most important manufacturing processes. In the additive manufacturing process, the mass of the parts is directly related to the printing duration, in addition to the costs of consumables. On the other hand, the use of lighter parts in industries, such as the aviation, is one of the important requirements of those industries, and topology optimization is needed to reduce the consumables and the mass of the parts. Also, since in the optimal design of engineering parts, more than one design objective is usually considered, the multi-objective optimization of topology is of great importance. The Moving Morphable Components is one of the new... 

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... 

Optimizing multi-period modern distribution system is a challenging task due to high costs of constructions in urban areas and importance of fast and cheap goods delivery to customers. Various logistic techniques have been proposed to solve this issue. In this study, a new method is suggested to convert the strategic problem of finding depot location into a tactical problem. In addition, a vehicle routing method for multi-period distribution systems in high demand periods have been developed. For modeling this location-routing problem two objective functions have been considered as fallows minimizing the total time in the system to satisfy customer demand and operating costs. To solve this...