Sharif Digital Repository

This thesis consists of three main chapters. The first chapter is about describing principles about offshore wind turbine, principal concepts. This chapter also explains about advantages and disadvantages of installing wind turbine at offshore fields, and economical aspect of this kind of wind turbine farms. In the second chapter,anumerical method is used to investigate a SeaStar tension leg platform offshore wind turbine response behavior in parked condition. This code considers nonlinearities due to changes in tension of tethers. Wave forces are calculated adopting the Airy wave theory. Furthermore, shear turbulent wind is exerted on tower, with maximum speed 30 m/s on the hub. Since surge... 

Use of wind energy is always one of the aims of man during the times. He used this energy for wheat grinding and sometimes for marine transportations. During recent decades, technology development forced human to harness this energy and use that for electricity production by employing onshore wind turbines. However, the modern engineering employed different arms of engineering such as marine engineering, civil engineering, mechanical engineering and electrical engineering for designing and installation of offshore wind turbines. But, huge water depths in offshore regions make the fixed leg turbines to be unacceptable solution. So, the floating wind turbines with mooring lines which attach... 

Today, to reduce the effects of greenhouse gases on the earth, as well as reduce dependence on fossil fuels and other non-renewable sources, the international community is moving towards greater use of renewable energy. The oscillating water column device as a wave energy converter system has the ability to use and absorb energy within the waves through a chamber consisting an air and a water column. This system has the ability to move the turbine installed on the valve by expanding and compressing the air passing through the valve. Oscillating water column systems have different categories, and this high diversity makes the choice of this wave energy converter closely related to the... 

Super cyclone GONU formed on June 2007 has been recognized the strongest tropical cyclone in the North Indian Ocean (NIO). The aim of this study is to numerically simulate the cyclone GONU and its resulting waves in the southern seas of Iran leading to the best parametric model to simulate future occurrence of tropical cyclones (TCs) in the NIO. In this regard, the best track data of the cyclone is extracted from Indian Meteorological Department (IMD). The cyclone GONU wind field is simulated by Young and Sobey, Holland, and Rankin models in order to determine the most appropriate model which is then considered for regenerating cyclonic wind fields over the Makran coastline and the sea of... 

One of the most significant challenges and issues that port engineers and coastal specialists face in the field of improving port performance is the design and development of hardware systems to enhance the efficiency of loading and unloading operations of ships. These systems need to be designed in a way that reduces the duration of loading and unloading operations of ships and improves the efficiency of cranes. One efficient technology in this field is the Automatic Mooring Systems, which are connected to the hull of berthed ships and use hydraulic cylinders to generate control forces. On the other hand, as evident in today's world, artificial intelligence is recognized as a vital and key... 

The optimal design of a ground-coupled heat pump (GCHP) system with vertical ground heat exchanger (VGHX) includes thermal modeling of the system and selection of optimal design parameters is presented in this research. Then, by applying Nelder-Mead optimization algorithm, an objective function (Total Annual Cost which is the sum of annual investment and operating costs of the system) is defined and minimized, exposed to specified design constraints. Also, Genetic Algorithm is used to verify the optimal design process. In order to evaluate the accuracy of a presented model, the optimum values of a heat pump design parameters includes saturated temperature/pressure of a condenser and... 

Petroleum is the main source of energy in the world. So, exploration and production of this strategic matter from earth and sea has a major importance. A large amount of this black gold is hidden under deep seas floors and extraction of these sources requires knowledge of design and technology of construction of deep water offshore platforms and equipments. Convetional Tension Leg Platform (CTLP), configured as 4 cloumns and 4 pontoons, is one of deep offshore platforms moored by several pretensioned tethers. The dynamic behavior characteristics of CTLPs are extracted in this thesis by numerical modeling of CTLP and regular wave interaction. A computer program PARADISE is developed in... 

every year large amounts of sedimentation are getting dredged all over the world. Dredging operation includes several processes such as excavating from the sea bottom, transferring them to the surface, and most important, releasing them in another area which can cause a sediment particle cloud that can be really harmful to the surrounding environment. Therefore, accurate analysis of this phenomenon is necessary to prevent catastrophic damages. The Eulerian-Lagrangian numerical method considers both sediment particles and fluid physics for a better simulation of near-field area. In this project, after investigating open-source available software for the Eulerian-Lagrangian simulation, a new... 

The necessity of electrical energy, high cost of big power plants and high voltage transmission lines and also progressing of restructuring science has lead to the increasing of tendency to use the distributed generation in electrical industry. Among of different types of distributed generations, fuel cell power plants because of many advantages such as high efficiency, low emission, modular structure and ect., have a high potential to be used in power systems. The fuel cells produce electrical energy by chemical reactions. Due to the necessity of having the knowledge related to the chemical reaction which are effective on fuel cell, to study the fuel cell performance, this type of... 

Sea and ocean waves develop in various ways especially by blowing wind over them. Modeling of these waves has been in center of interest for half a century. After the pioneering study of Gelchi et al (1995), ocean wave models are generally base on a spectral energy or action balance equation. Ocean storms such as tropical cyclone will develop if the atmospheric and oceanic conditions are available. Their Rotational and transition movement causes different patterns of waves. In 2007, cyclone Gonu, a tropical cyclone that formed in Indian ocean and have steered to Oman Sea and also caused damages and casualties in southern coast of Iran. Since intense tropical cyclones such as Gonu have... 

With the increasing penetration of renewable energies as distributed generation (DG) in power systems, technical problems arise in both distribution and transmission system level. Voltage rise is the main barrier for connection of DGs in rural areas, while excessive reactive power demand from transmission system is the major concern for Transmission System Operators (TSO). Here, a centralized control scheme based on the Smart Grid is proposed to reduce the impact on the transmission system voltages and improve its stability, while mitigating the voltage rise issue in the distribution network. Reactive power output of DGs, substation capacitors and tap setting of transmission transformer are... 

The demand in water and energy for household, industrial and agricultural uses continue to grow. In recent years, many researches have been done on thermodynamic assessment and optimization of Combined Cooling, Heating and Power (CCHP) and desalination systems. The interesting and important point is the potential of combining CCHP and desalination systems by employing the solar power. The purpose of this study is exergy analysis and thermoeconomic optimization of a hybrid system of Multi-Effects Distillation desalination (MED) and CCHP, augmented by solar energy. The thermoeconomic analysis is carried out by Total Revenue Requirement (TRR) method. Properties of working fluid in hybrid MED... 

Based on codification and implementation of regulations of supporting from development of distributed generation sources, it is expected that in future years, investment in distributed generation scheme will be welcomed by private investors impressively. Under this circumstances, distribution Company will be faced with new chances for improving quality level of their services and optimal management of penalty-reward schemes. Penalty-reward schemes is set by legislator for distribution Company in order to improve their network. One of the pioneer ways is using distributed generators. So first, distribution Companies have to find optimum places for using these generators and in the second step... 

With regards to rapid growth of world population, coastlines have limited natural resources and capacity for human settlement. To tackle the problem the idea of constructing artificial islands could be a solution. Since the artificial islands are semi-enclosed body of water designed to attract not only tourists but also settlements, the flow current pattern and residence time of water should be studied in detail in order to ensure adequate water quality in the surrounding area. In this study, an artificial island is planned to be constructed around Kish Island in Persia Gulf. In this article the effects of different geometries on circulation and residence time of water are investigated... 

Recent studies have shown that almost 40% of the world's population faces a water crisis, and this amount will reach about 60% by 2025. Due to limited freshwater resources and the increasing world population, we have to use seawater desalination systems to supply water to this growing population. One of the outputs of desalination plants in addition to freshwater is saline effluent or brine water, which is the most important environmental impact of these plants. In this study, an attempt has been made to investigate the various factors affecting the discharge and release of saline effluent from desalination plants and observe its impact on the ecosystem and marine environment. In this... 

The sea's ecosystem is the most sensitive and essential as the last recipient of sea and land pollution. The increasing requirement for building thermal power plants and desalination plants and a great demand for their thermal effluents discharge causes a serious threat to the rich coastal environment. In this project, a general study on environmental and meteorological data required to investigate the environmental effects of effluent discharge from desalination plants in the Persian Gulf and the Sea of Oman has been conducted, and the general process of conducting thermal effluent discharge research in this area is presented. Next, in a case study using MIKE hydrodynamic software and... 

Today, as an effective tool for marine applications, towed submarines play an im-portant role in various sectors of the marine industry, including defense, recreation, ocean exploration, etc. The high cost of existing thrust systems, as well as the signifi-cant vibrations in them, run counter to the goal of designing this small, low-cost sub-marine. Therefore, the decision was made to design this vessel with a tensile thrust system. In this project, an attempt is made to introduce and design the structure of the body and the carrying capacity of the passenger by a recreational submarine with the ability to move 10 people as passengers And while introducing the structure of the body shape and... 

Many species in nature exist which human can reach the aims of flying and swimming by inspiring from them. Observations show that fish can use their especial undulating motions of body/fins to crusing, increase performance, suddenly acceleration, and maneuvering. To design a robot fish and benefit the characteristics and abilities of a live fish, using its real geometry and kinematics in the robot is vital. Therefore, simulations are essential to better exploiting the fish behavior, which can obtain useful consequences by using computational fluid dynamics. In this thesis, first the kinematics of sharks is investigated. Then, investigations are accomplished by utilizing an unsteady finite... 

Limited fossil resources, daily increase of demand for energy and the most important one that is environmental pollution fact, make people think of renewable energy as a solution. One type of these renewable energies is offshore wind energy that has high potential without any sound and visual noises. Recently a lot of researches have carried out their studies on the topic of offshore wind turbine. Cause of disabling of a lot of software to simulating of dynamic effect of rotating rotors, so in this research has make effort to fabricate and test an offshore wind turbine with different rotor rotating velocities and different heading angle of wind, to catch the effect of these parameter on the...