P. . Atabak; S. Allahyaribeik; F. Azarsina
Volume 4, Issue 2 , June 2014, Pages 57-64
Abstract
This study aims to examine the performance of the rock materials in the protective layer of rubble-mound breakwaters in southern Iran, from Rostami Port in Bushehr Province to Beris Port in Sistan and Baluchestan Province. Field inspections were carried out on a great number of rubble-mound breakwaters ...
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This study aims to examine the performance of the rock materials in the protective layer of rubble-mound breakwaters in southern Iran, from Rostami Port in Bushehr Province to Beris Port in Sistan and Baluchestan Province. Field inspections were carried out on a great number of rubble-mound breakwaters built in the Persian Gulf and Oman Sea coastal regions to study the protective layer of these breakwaters under ambient conditions as well as to detect the damage caused by factors affecting the failure of the used materials. Subsequently, samples were taken from these rock materials, the specimens were tested in accordance with various quality assessment criteria, and the results were compared with those obtained from international standard tests. The obtained results showed that in most cases, the physical and chemical properties of the local rock materials did not meet standard requirements. As such, these materials are not recommended for use in the construction of breakwaters. In practice, however, these rocks exhibit an acceptable performance in certain cases depending on the position of each rock group in the structure of the breakwater. For this reason, design, construction, and structural considerations can somehow influence the performance of these rock materials in the respective marine structures.
M. Arabi; F. Azarsina
Volume 4, Issue 2 , June 2014, Pages 65-76
Abstract
Scour is a phenomenon that occurs as a result of natural erosion by ground water flow and transport of seabed material. In this research, scour around the legs of marine structures is simulated using the FLOW3D.V.9.3™ commercial software. The general scour model consists of two components, namely, ...
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Scour is a phenomenon that occurs as a result of natural erosion by ground water flow and transport of seabed material. In this research, scour around the legs of marine structures is simulated using the FLOW3D.V.9.3™ commercial software. The general scour model consists of two components, namely, the lift and thrust forces. The drag force, that is inserted to the structure, is a combination of those two components. As the sediment concentration equals the volume fraction of cohesion, the drag force that determines the rigidity of the sediment model, is activated. Also, as the sediment concentration changes, the viscosity and density of the fluid changes. The numerical model used in this research is similar to the experimental set-up that was performed in a sedimentation tank two meters long, 1.5 m wide and 0.3 m high; while the sandy sediment particle diameter was 0.084 cm. The numerical model implements an RNG turbulence model. After the studies, the time to reach equilibrium in the model was 100 seconds. The relative error between experimental and numerical scour depth is about 10 percent. Scour depth was determined for legs with circular and elliptic as well as for rectangular base shapes with different aspect ratios. Numerical results indicate that the scour depth decreases for the more streamlined elliptic base shapes. Also, the effect of water depth on scour depth, while all other parameters are kept constant, is a linear relationship. Finally, as sediment particle diameter increases, scour depth decreases.
K. Kashizadeh; A. Sarvghad Moghadam; F. Azarsina
Volume 4, Issue 2 , June 2014, Pages 77-88
Abstract
Offshore structures such as jacket platforms have to inevitably be designed against sever environmental actions. In seismically active areas these structures also become susceptible to earthquake excitations. Strong ground motions recorded in recent earthquakes, including the 1995 Kobe, ...
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Offshore structures such as jacket platforms have to inevitably be designed against sever environmental actions. In seismically active areas these structures also become susceptible to earthquake excitations. Strong ground motions recorded in recent earthquakes, including the 1995 Kobe, Japan, 1999 Chi-chi, Taiwan and 1999 Kocaeli, Turkey earthquakes, revealed that the dynamic motions in near fields are dominated by a large, narrow band, long period pulse caused by rupture directivity effects. Sever damages have been reported with specific bridges, quay walls and multistory buildings near to the shaking fault. It was been noticed that the dynamic characteristics of these structures were close to the characteristics of the rupture directivity and felling pulses.This paper deals with the behavior of existing jacket platform under near field earthquake loading. As an example seismic assessment of the existing 4 legged service platform placed in Persian Gulf is presented. A finite element approach utilizing “Opensees” Standard software has been chosen for this study. A dynamic non-linear direct integration analysis method has been used. Seven, near and far fault records have been examined. In general it has been found that the far field excitations produce more critical consequence for the jacket offshore platform as compared with those from the corresponding near field excitations. It has been noticed that the correspondence between the dominant frequency of the record and the main natural frequency of the jacket structure can be used as a criteria to decide whether a far or near field Earthquake is more critical.
M. Abbaspour; A.R. Radmanesh; M.R. Soltani
Volume 4, Issue 2 , June 2014, Pages 89-100
Abstract
To indicate the best airfoil profile for different sections of a blade, five airfoils; included S8xx, FFA and AH series was studied. Among the most popular wind power blades for this application were selected, in order to find the optimum performance. Nowadays, modern wind turbines are using blades with ...
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To indicate the best airfoil profile for different sections of a blade, five airfoils; included S8xx, FFA and AH series was studied. Among the most popular wind power blades for this application were selected, in order to find the optimum performance. Nowadays, modern wind turbines are using blades with multi airfoils at different sections. SST-K-ω model with different wind speed at large scale profile applied to simulation of horizontal axis wind turbines (HAWT). The aerodynamic simulation was accomplished using Computational Fluid Dynamic (CFD) method based on the finite volume method. The governing equations apply in this simulation are the Unsteady Reynolds Averaged Navies Stocks (URANS) equations. The aerodynamic coefficients of lift and drag were calculated at different angles of attack and different wind speeds. The results are validated by Eppler code, Xfoil and experimental data of the U.S National Renewable Energy Laboratory (NREL). The results show that S818 profile is the best profile in terms of gaining the highest lift coefficient with the lowest angel of attack at the root of the blades. The results also indicated that the selected model can predicted the exact geometry with a high precision.
N. . Allahyaribeik; S. Allahyaribeik
Volume 4, Issue 2 , June 2014, Pages 101-106
Abstract
In recent years, the application of Activity-Based Costing in Port industry has been deeply researched in theory and practice, but researchers only concentrate on the bulk and general cargo’s ABC in loading and unloading operations and there is little about the liquids and chemicals’. Based ...
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In recent years, the application of Activity-Based Costing in Port industry has been deeply researched in theory and practice, but researchers only concentrate on the bulk and general cargo’s ABC in loading and unloading operations and there is little about the liquids and chemicals’. Based on the liquids and chemicals’ handling process and the particularity of their cost accounting, the paper establishes quality and safety activity center, steam heating, electric trace heating activity center, temperature maintenance activity center and so on .At the same time, the paper focuses on their cost drivers and their measuring method in order to improve the accuracy of costing in loading and unloading operations.
M. Alipour; M. Fallahi; T. Valinassab
Volume 4, Issue 2 , June 2014, Pages 107-111
Abstract
In this study, effects of pH and salinity on growth and bloom of Dunaliella sp. algae were investigated. The algae were reared in different pH (6.0, 6.8, 7.0, 7.3, 7.6, 8.0, 8.6, 9.0, 9.7 and 11.0) and salinities (20.0, 31.6, 50.1, 79.4, 117.1, 125.9 and 200.0 ppt) at Inland Aquaculture Research Institute ...
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In this study, effects of pH and salinity on growth and bloom of Dunaliella sp. algae were investigated. The algae were reared in different pH (6.0, 6.8, 7.0, 7.3, 7.6, 8.0, 8.6, 9.0, 9.7 and 11.0) and salinities (20.0, 31.6, 50.1, 79.4, 117.1, 125.9 and 200.0 ppt) at Inland Aquaculture Research Institute Phycolab during 2011. After 96 h, the algae reared in 50ppt salinity and below that had negative growth, however, beyond the 50 ppt, it started to grow and reached the growth peak in 117.1 ppt. In 125 and 200 ppt, the algae growth decreased compared to 117.1 ppt. Exceptsalinityof31.62and50.11descendant of the other groups was significant (P < 0.05). At the different pH, after 96 h the lowest growth was observed in pH 11, whereas, the highest growth was in pH 7.6 while increasing pH above 9.0 led to negative growth. These differences were significant (P <0.05).