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Dynamic response of a moored semisubmersible in short-crested wave fields
, Article Scientia Iranica ; Volume 11, Issue 4 , 2004 , Pages 351-360 ; 10263098 (ISSN) ; Borghei, S. M ; Sohrabpour, M ; Sharif University of Technology
Sharif University of Technology
2004
Abstract
Wind generated sea states are more accurately modeled by short-crested wave fields. Whether or not these short-crested waves can induce larger response amplitudes in floating offshore structures is of great concern to offshore engineers. In this paper, the hydrodynamics of a moored semisubmersible in short-crested wave fields is investigated. Morison-based motion equations with nonlinear damping terms are used to analyze the dynamic behavior of the structure. A generalized three-parameter short-crested wave field is introduced as the incident wave. The effect of transverse phase lag, wave propagation angle and different ratios of in-line and transverse wave numbers are studied on the force...
Experimental investigation on response and efficiency of moored pontoon type floating breakwaters
, Article Iranian Journal of Science and Technology, Transaction B: Engineering ; Volume 31, Issue 1 , 2007 , Pages 95-99 ; 03601307 (ISSN) ; Akbari, M ; Sharif University of Technology
2007
Abstract
This paper presents the experimental results of an investigation on the response and efficiency of floating pontoon type breakwaters. Random waves modeled by the Pierson Moskowits wave spectrum are used for various configurations of floating breakwaters. The experimental results are presented in graphs for the transmission coefficient as a function of incident wave length and height for breakwaters used in this study. The obtained results for the breakwaters of this study show that by increasing the wave period and length, the transmission coefficient increases, while increase in the mass and draft of the floating breakwater causes the transmission coefficient to reduce. © Shiraz University
Aero-Hydro-Elastic Analysis of a Floating Beam in a Water Channel Subjected to Cross Wind
, M.Sc. Thesis Sharif University of Technology ; Dehghani Firouzabadi, Rouhollah (Supervisor)
Abstract
In static floating structures such as floating bridges and offshore runways that are in contact with the water surface from the floor and with the open air from the top, three types of interactions occur: the interaction of the structure with air, the interaction of the structure with water and Interaction of air with water. Due to the long length of such structures and approaching their natural frequencies to the standing wave frequencies (seiche frequencies), the analysis of the elastic behavior of the structure alone is not enough, but the structure-air-water interaction must be evaluated simultaneously in a system. Leading research addresses this issue and examines the behavior of an...
Feasibility Study and Design of Artificial Energy Island (in Persian Gulf Region)
, M.Sc. Thesis Sharif University of Technology ; Abbaspour Tehranifard, Majid (Supervisor)
Abstract
As it is obvious from the name of this study, the goal of doing this study is the feasibility study of southern shores of Iran for building an artificial energy island for and designing it. In this project by studying seven points coastwise of southern Iran and defining the criterions and scoring the points, the Chabahar was determined as the best place for erecting the artificial energy island. With respect to the environmental condition of the chosen point and modeling in software ANSYS, the structure of the artificial energy island has been studied and the type, geometric shape, area, trough, and the setting of the anchoring system has determined. As a result of these efforts, a hexagon...
Floating bridge modeling and analysis
, Article Scientia Iranica ; Volume 12, Issue 2 , 2005 , Pages 199-206 ; 10263098 (ISSN) ; Paein Koulaei, R. T ; Sharif University of Technology
Sharif University of Technology
2005
Abstract
This paper presents an overview of a study on the design and analysis aspects of the Lake Urmia Bridge in Iran. For years there have been several detailed investigations on this subject. Here, these alternatives are discussed and, then, results of analyses for a proposed solution, a floating bridge, are presented. These aspects include environmental loads, structure and the mooring system. © Sharif University of Technology
Hydrodynamic performance of multiple co-axial heave plates with different diameters
, Article Ships and Offshore Structures ; Volume 15, Issue 4 , 2020 , Pages 380-392 ; Behzad, M ; Thiagarajan, K. P ; Sharif University of Technology
Taylor and Francis Ltd
2020
Abstract
Heave plates are structural components of a floating structure whose primary purpose is to increase damping and added mass in heave or pitch direction. If multiple plates are stacked along a common axis, then the relative diameters and spacing in between are important factors affecting the performance. In the present study, hydrodynamic coefficients of single, double and triple disks are experimentally investigated in different arrangements as Uniform, Concave and Convex edge shapes. It is observed that each disk in a multiple arrangement with lower diameter ratio have better hydrodynamic performance compared to the cases with higher diameter ratio when the spacing is small compared to the...
Multi model robust control design for a floating offshore variable speed wind turbine with tension leg platform
, Article Ocean Engineering ; Volume 266 , 2022 ; 00298018 (ISSN) ; Sadati, N ; Member, IEEE ; Sharif University of Technology
Elsevier Ltd
2022
Abstract
This paper presents a multi-model robust control (MMRC) design for an offshore variable speed wind turbine with tension leg platform. The proposed control scheme covers the model uncertainty in the above rated wind speed, and it provides a reliable control for power regulation while minimizing the mechanical loads on the wind turbine structure. For this purpose, the above rated wind speed region is divided into several wind speed groups, and a set of linearized models are obtained from the Fatigue, Aerodynamics, Structures, and Turbulence (FAST) simulator for various mean wind speeds of each group. Using Weibull wind speed distribution, a nominal model with additive uncertainty is generated...