Sharif Digital Repository

This project deals with the global buckling in high pressure/high temperature (HP/HT) subsea pipelines. Some subsea pipelines are laid directly on the seabed. Large axial forces will generally cause an exposed pipeline to buckle sideways, or laterally, on the seabed. Pipelines may significantly expand during start-up and shutdown cycles, resulting in global buckle formation with high out-of-straightness (OOS).This global buckling behavior may be unacceptable if it is not properly managed. Global buckling mitigation can be achieved by providing controlled lateral movements of pipeline. Buckle mitigation devices are installed along the pipeline to provide buckle initiation sites, there by... 

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... 

Nowadays because of population growth and limitation of fossil fuels for power generation purpose, utilization of renewable energy sources has become highlighted. According to the geographical situation for use of wind energy, since some areas of Iran are in suitable conditions the manufacture of wind turbines and installation in wind farms has been under development recently. Monitoring the performance and operation of turbines and wind farms is an inevitable matter. Because of the suitable geographical location of Iran and pursuant to fair wind potential sites widespread this country, this phenomenon requires some backgrounds in many aspects to be achieved. One of the most important... 

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... 

Industry Success leads to the use of fossil fuels in communities that result to climate change in the world. Among these effects, there is the effect on the severity, extent and duration of precipitation. Hydroelectric plants are clean and cheap energy resources in the world that due to the use of water, the phenomenon of climate change are very impressionable. Regarding high costs of construction and maintenance of these dams in order to exploit their lengthy; Impact of climate change on them is important issue.
In this research, first a nonlinear optimization model to maximize hydroelectric power generation by genetic algorithms in the MATLAB software environment has been developed.... 

There is increasing demand for water due to rising world population. In addition, lower supplies of water under varying hydrological condition because of changing climate, renders further stress on an already over-allocated water resource. Thus, this condition would exacerbate water supply-demand conflicts resulting in penalties on local economy. On the other hand fresh water as a scarce resource requires comprehensive management. To maintain fresh water resources, systems need principles of ecologically sustainable development that keeps environmental uses as legal. Hence, in this situation there is a need to develop appropriate methods to minimize the climate change consequences and... 

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 main methods to reduce fuel consumption and emissions is using renewable energy resources. This research proposes a hybrid renewable energy system on a container ship which includes one photovoltaic solar system, and one kite system. The photovoltaic system produces a part of the ship's electric power consumption and the kite system produces propulsion force using wind energy and transmitting this force to the ship through towing rope. Different components of these renewable energy systems are connected with the internet of things technology. In the internet of things structure design section, in addition to the conceptual design of different layers with emphasis on the processing... 

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... 

In this research, a method based on the modified Enskog theory (MET) and some equations of state has been used to calculate the transport properties of some dense fluids. The main limitation to using the MET is the lack of experimental data for the co-volume, b0, that are substituted from the hard sphere (HS) theory, and the zero density transport properties that are substituted from the kinetic theory of gases for the HS in the MET expression, because of the fact that dense fluids behave more and less like a HS fluid. So a quadratic expression for both ηY/(√T ρ) and λY/(ρ√T) (C_(V,m)+ (9/4)R) in terms of Y at high densities (ρ > ρc) for each isotherm is expected, where Y = (T (∂p/∂T))/ρRT... 

The endeavors towards achieving a sustainable management of supply chains have brought about new cardinal logistic aims in addition to the common cost minimization objective. Traditional and sometimes disoriented constraints and assumptions such as demand certainty, infinite shelf life of products and so forth have resulted in a noticeable number of improper decisions made by supply chains’ members. Furthermore, intensified environmental concerns, consumers’ awareness of health problems, growth of demand for high quality products, scarcity of natural resources, etc. have brought many challenges and complexities to inventory management and routing problems. Due to supply chain managers’ and... 

In this research we will develop an algorithm to find the optimal robust solution via simulation optimization by using an artificial neural network metamodel. Following Taghuchi, in design phase of the algorithm, we will discriminate between decision or control variables and environmental or noise variables. To arrive of the best new solution in every iteration, the algorithm will use a symmetrical probabilistic distribution about the optimum point of the previous iteration. In comparison with the existing methods, our algorithm displays an improvement in results when applied to such problems as single channel queueing system problem and economic order quantity problem