V. Zarepoor; E. Ezam; S Allahyaribeik
Volume 5, Issue 1 , January 2015, Pages 1-13
Abstract
Thermocline layer have remarkable effects on acoustic propagation in Persian Gulf environment. So far, no comprehensive research has been conducted to explore thermocline layer, especially its characteristics including top, thickness, and thermal gradient of thermocline in Persian Gulf. Besides, effects ...
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Thermocline layer have remarkable effects on acoustic propagation in Persian Gulf environment. So far, no comprehensive research has been conducted to explore thermocline layer, especially its characteristics including top, thickness, and thermal gradient of thermocline in Persian Gulf. Besides, effects of thermocline on underwater acoustic propagation including transmission loss and sound channel formation in Persian Gulf have not been investigated as most studies to date have focused on the effect of thermocline on transmission loss in low frequencies, while high frequencies have been studied less. Accordingly, this study attempts to shed light on these ambiguities. ROPMI Cruise measurement data collected during summer (August) of 2001 in Persian Gulf were used in this study. To simulate the acoustic propagation, ray-tracing theory was also applied to make possible an analysis of high frequencies. Results showed that presence of thermocline layer have remarkable effects on transmission loss. Increasing the gradient in thermocline layer will raise transmission loss.
M. Abdoli; F. Azarsina; M.H. Givian Rad
Volume 5, Issue 1 , January 2015, Pages 15-21
Abstract
Today due to increasing development and importance of petroleum activities andmarine transport as well as due to the mining of seabed, building activities such as construction of docks, platforms and structures as those in coastal areas and oceans has increased significantly. Concrete strength as one ...
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Today due to increasing development and importance of petroleum activities andmarine transport as well as due to the mining of seabed, building activities such as construction of docks, platforms and structures as those in coastal areas and oceans has increased significantly. Concrete strength as one of the most important necessary parameters for designing, depends on many factors such as mixture plan ofconcrete, concrete forming materials, and curing conditions. Since many of these factors are uncertain and cannot have a specific and accurate formulation for concrete strength, therefore, applying a pre-set mathematical formula roughly predicts the strength of concrete. Inthis research,Genetic algorithm optimization for concrete mix plan is presented. Genetic algorithms are searching algorithms that have been established based on mechanism of natural selection and evolution. These algorithms select the most appropriate strings from organized random data.In every generation, a new group of strings by using the best parts of previous and new accidental sequencewill happen to get a proper answer.First a suitable encoding (or representation) must be found for the problem. The most common representation method of chromosomes in genetic algorithms is in the form of binary strings which is the method used in this study. By iteratingthe computation of marine concrete generation, optimized mix concrete design is achieved.Accordingly, with more detailed information of marine-grade concrete and application of genetic algorithm based on generational leap it can be expected that a new generation of marine concrete will be recoverable
M. Hosseini; SH. Rahmanpour; A Mashinchian Moradi
Volume 5, Issue 1 , January 2015, Pages 23-29
Abstract
Heavy metal metals are non-biodegradable, have a remarkable ability to transfer through food chains and are potentially toxic for organisms.They are introduced tomarine environment via different anthropogenic sources. In this study, the ability of titanium dioxide nano-particle in transfer of Cr, Cu, ...
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Heavy metal metals are non-biodegradable, have a remarkable ability to transfer through food chains and are potentially toxic for organisms.They are introduced tomarine environment via different anthropogenic sources. In this study, the ability of titanium dioxide nano-particle in transfer of Cr, Cu, Pb and Se metal through an aquatic food chain involving Ceratium tripos as the phytoplankton Daphnia hyaline as the zooplankton and Liza abu as the fish was investigated. The phytoplankton specie Ceratium tripos was exposed to 0, 0.2 and 0.5 of TiO2. Subsequently, each species was fed to the zooplankton Daphnia hyaline, which was then used as food for the fish Liza abu. There were significant differences between the level of Cr, Pb and Se among the groups. The results showed that Cr and Se are biomagnified through the food chain. Whereas, Cu, which is essential element and could be regulated by organisms body, and Pb were not biomagnified through the chain.
M. Hosseini manash; M.J. Ketabdari
Volume 5, Issue 1 , January 2015, Pages 31-40
Abstract
FPSOs are useful in newly established offshore oil regions where there is no pipeline infrastructure in place, or in remote locations where building a pipeline is cost-prohibitive. In this study, hydrodynamic analysis of FPSO is inquired based Boundary Element Method (BEM) and wave forces/moments, ...
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FPSOs are useful in newly established offshore oil regions where there is no pipeline infrastructure in place, or in remote locations where building a pipeline is cost-prohibitive. In this study, hydrodynamic analysis of FPSO is inquired based Boundary Element Method (BEM) and wave forces/moments, added mass and damping coefficients of degrees of freedom are obtained by AQWA software. FPSO moored with mooring lines and developed a MATLAB code to calculate stiffness matrix. Then the responses of FPSO for three conditions, without mooring line, with three mooring lines and twelve mooring lines are illustrated. The results show that mooring system is effective in the reduction of surge response, but it has not major effect in increasing of heave and pitch responses.
F. Orak; M. Bakhtiari; H. Bahrami
Volume 5, Issue 1 , January 2015, Pages 41-47
Abstract
Seawalls are built for Protecting of beaches against waves and preventing the progression of water to the beach. For a proper understanding about these constructions, a suiTable information about applied loads on these constructions should be existed. One of the important load that applied on these constructions ...
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Seawalls are built for Protecting of beaches against waves and preventing the progression of water to the beach. For a proper understanding about these constructions, a suiTable information about applied loads on these constructions should be existed. One of the important load that applied on these constructions is sea wave. Others loads are included: weight force of the walls, weight force of the soil behind wall, weight force of the sea water on wall base and the forces applied on beach. Seawalls are built in different geometric shapes like vertical, Inclined and curvature walls (with variable slope). In this study, 4 geometric shape: vertical, Inclined, Convex and concave are simulated for analyzing the effect of geometry on stability of seawalls. So FLAC 3D software are used. The results show that the minimum earth subsidence and horizontal displacement are obtained for convex wall and the maximum amount of these parameters for vertical wall.
M. Atashrazm Jirande; F. Azarsina; M.S. Seif
Volume 5, Issue 1 , January 2015, Pages 49-54
Abstract
During design spiral of a merchant ship or a naval vessel, it is important to perform towing tank tests in order to measure its performance either in calm water maneuvers or in waves for seakeeping performance. Also, to optimize a hydrodynamic design, towing tank tests are advantageous.This article presents ...
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During design spiral of a merchant ship or a naval vessel, it is important to perform towing tank tests in order to measure its performance either in calm water maneuvers or in waves for seakeeping performance. Also, to optimize a hydrodynamic design, towing tank tests are advantageous.This article presents the results of an applied research project. The objective of this project is to design and manufacture a six-componentbalance dynamometer to measure drag force, lateral force, yaw moment, roll moment, andheave and pitch motions. Various stages of this work are presented in the text. The main steps of this activity are to design, prototype,and install strain gauges, and eventuallycalibratethem. Using this procedure, implementing the relevant criteria, the appropriate measures of the strain were selectedmore on the basis of recommendations of professional bodies.Material selection of suitable metal machining and construction work is done. Next, the strain meters were installed onthe balance. After equipment calibration, dynamometer is ready for the ultimate test in towing tank