Investigation of Dimension Changes in Under Pressure Hydraulic Sediment Flushing Cavity of Storage Dams Under Effect of Localized Vibrations in Sediment Layers

Dodaran, Asgar Ahadpour,Park, Sang-Kil,Mardashti, Asadollah,Noshadi, Masoud Korean Society of Ocean Engineers 2012 International journal of ocean system engineering Vol.2 No.2

Several methods have been proposed to control the sedimentation process. These include catchment management, flushing, sluicing, density current venting, and dredging. Flushing is used to erode previously deposited sediments. In pressurized flushing, the sediment in the vicinity of the outlet openings is scoured and a funnel shaped crater is created. In this study, the effect of localized vibrations in the sediment layers on the dimensions of the flushing cone was investigated experimentally. For this purpose, experiments were carried out with two bottom outlet diameters, five discharge releases for each desired water depth, and one water depth above the center of the bottom outlets. The results indicate that the volume and dimensions of the flushing cone are strongly affected by localized vibrations.

Development of Design Static Property Analysis of Mooring System Caisson for Offshore Floating Wind Turbine

Dodaran, Asgar Ahadpour,Park, Sang-Kil Korean Society of Ocean Engineers 2012 International journal of ocean system engineering Vol.2 No.2

A all floating structures operating within a limited area require, stationkeeping to maintain the motions of the floating structure within permissible limits. In this study, methods for selecting and optimizing the mooring system Caisson for floating wind turbines in shallow water are investigated. The design of the mooring system is checked against the governing rules and standards. Adequately verifying the design of floating structures requires both numerical simulations and model testing, the combination of which is referred to as the hybrid method of design verification. The challenge in directly scaling moorings for model tests is the depth and spatial limitations of wave basins. It is therefore important to design and build equivalent mooring systems to ensure accurate static properties (global restoring forces and global stiffness).

Semi-resolution Practicability of Three-Dimensional Statics of Cables from Computer Programs

Asgar Ahadpour Dodaran,SangKil Park 한국해양공학회 2012 韓國海洋工學會誌 Vol.26 No.6

he purpose of this paper is to present a rational method for analyzing designing, or evaluating the spread mooring systems used with floating drilling units. This paper presents a validated model to calculate the catenary static configuration. A semi-resolution approach is presented in this paper that is capable of predicting the static performance of a caisson mooring system. The solution is derived as a function of only three parameters, which can be solved numerically by implementing different kinds of boundary conditions. The efficiency and accuracy of the method permit quick parametric studies for the optimal selection of the system particle, which is undoubtedly useful for a preliminary design. A number of numerical examples demonstrate the validity of the adopted approach. The paper contains a complete description of the test cases and reports the results in such a way that it can provide a “benchmark” test for users and programmers of computer codes for flexible riser analysis.

Effects of Roughness and Vertical Wall Factors on Wave Overtopping in Rubble Mound Breakwaters in Busan Yacht Harbor

Asgar Ahadpour Dodaran,Sang Kil Park,Kook Hyun Kim,Mohammad Ebrahim Meshkati Shah,Hong Bum Park 한국해양공학회 2015 韓國海洋工學會誌 Vol.29 No.1

Coastlines are protected by breakwater structures against the erosion of sand or other materials along beaches due to wave action. This research examined the use of physical modeling to determine the effects of the tetrapod size and vertical walls of a rubble mound on the volume of wave overtopping under irregular wave conditions in coastal areas in Busan Yacht Harbor. In this analysis model, the structures were studied using irregular waves and the JONSWAP wave energy spectrum. To understand the effects of the tetrapod size and heights of the vertical wall, the study considered vertical walls of 0, 1.78, 6.83, and 9.33 cm with armor double layered material tetrapods of 8, 12, 16, and 20 tons. An extensive number of experiments covering a relatively large range of variables enabled a comprehensive discussion. First, in the presence of a short vertical wall, the water level played a key role in the overtopping discharge. In such circumstances, the values of the wave overtopping discharge decreased with increasing freeboard size. In the presence of a tall freeboard and middle, the value of the wave overtopping discharge was equally influenced by the vertical wall factor. Moreover, the tetrapod size decreased by an increase in the vertical wall factor, and relationship between them resulted in a short wall height. From an engineering point of view, considering a small water level may allow the choice of a shorter vertical wall, which would ultimately provide a more economical design.

Stability Analysis of Mooring System of an Offshore Floating Wind Turbines

Asgar Ahadpour Dodaran,SangKil Park,Jihun Lee 한국해양환경·에너지학회 2012 한국해양환경공학회 학술대회논문집 Vol.2012 No.5

Geometrically compliant mooring systems that change their shape to accommodate deformations are common in oceanographic and offshore energy production applications. Because of the inherent geometric nonlinearities, analyses of such systems typically require the use of a sophisticated numerical model. This thesis describes one such model and uses that model along with experimental results to develop simpler forms for understanding the dynamic response of geometrically compliant moorings. Scope of the research will then expand with applications to mooring systems of wave energy devices.

Stability Analysis of Mooring System of an Offshore Floating Wind Turbines

Asgar Ahadpour Dodaran,SangKil Park,Jihun Lee 대한조선학회 2012 대한조선학회 학술대회자료집 Vol.2012 No.5

Geometrically compliant mooring systems that change their shape to accommodate deformations are common in oceanographic and offshore energy production applications. Because of the inherent geometric nonlinearities, analyses of such systems typically require the use of a sophisticated numerical model. This thesis describes one such model and uses that model along with experimental results to develop simpler forms for understanding the dynamic response of geometrically compliant moorings. Scope of the research will then expand with applications to mooring systems of wave energy devices.

Experimental Investigation of Local Half-cone Scouring Against Dam under the Effect of Localized Vibrations in the Sediment Layers

Asgar Ahadpour Dodaran,Sang Kil Park,Asadollah Mardashti,Mehrzad Noshadi,Mohammad Afsari 한국해양공학회 2013 韓國海洋工學會誌 Vol.27 No.2

Most natural river reach are approximately balanced with respect to sediment inflow and outflow. Dam construction dramatically alters this balance, creating an impounded river reach characterized by extremely low flow velocities and efficient sediment trapping. The impounded reach will accumulate sediment and lose storage capacity until a balance is again achieved, which would normally occur after the impoundment has become “filled up” with sediment and can no longer provide water storage and other benefits. This paper aims to investigate the sediment removal process in dam reservoir using simultaneously pressure flushing operation and vibrator machine. The main objective of this study is to identify the effect of vibrator in flushing cone dimensions. To achieve the objectives of present study, laboratory test have conducted under different hydraulic conditions such as two bottom outlets with diameter equal to 2” and 3”, five discharges 0.23, 0.53, 1.21, 1.53 and 2.1 lit/s and only one water depth above the center of bottom outlets. Using the vibrator machine mounted into the reservoir and close to the bottom outlet, different frequency e.g. 20, 35 and 50 HZ, have been introduced to the deposited sediment at the vicinity of outlet. The results indicate that the volume and width of flushing cone are strongly affected by frequency of vibrations. The results indicate that the volume and width of flushing cone are strongly affected by frequency of vibrations.

Effects of vertical wall and tetrapod weights on wave overtopping in rubble mound breakwaters under irregular wave conditions

박상길,Asgar Ahadpour Dodaran,한종수,Mohammad Ebrahim Meshkati Shahmirzadi 대한조선학회 2014 International Journal of Naval Architecture and Oc Vol.6 No.4

Rubble mound breakwaters protect the coastal line against severe erosion caused by wave action. Thisstudy examined the performance of different sizes and properties (i.e. height of vertical wall and tetrapod size) of rubblemound breakwaters on reducing the overtopping discharge. The physical model used in this study was derived based onan actual rubble mound in Busan Yacht Harbor. This research attempts to fill the gap in practical knowledge on thecombined effect of the armor roughness and vertical wall on wave overtopping in rubble mound breakwaters. The maingoverning parameters used in this study were the vertical wall height, variation of the tetrapod weights, initial waterlevel elevation, and the volume of overtopping under constant wave properties. The experimental results showed thatthe roughness factor differed according to the tetrapod size. Furthermore, the overtopping discharge with no verticalwall was similar to that with relatively short vertical walls ( 1 v γ = ). Therefore, the experimental results highlight theimportance of the height of the vertical wall in reducing overtopping discharge. Moreover, a large tetrapod size mayallow coastal engineers to choose a shorter vertical wall to save cost, while obtaining better performance.

Spatial Inequalities in the Incidence of Colorectal Cancer and Associated Factors in the Neighborhoods of Tehran, Iran: Bayesian Spatial Models

Kamyar Mansori,Masoud Solaymani-Dodaran,Alireza Mosavi-Jarrahi,Ali Ganbary Motlagh,Masoud Salehi,Alireza Delavari,Mohsen Asadi-Lari 대한예방의학회 2018 Journal of Preventive Medicine and Public Health Vol.51 No.1

Objectives: The aim of this study was to determine the factors associated with the spatial distribution of the incidence of colorectal cancer (CRC) in the neighborhoods of Tehran, Iran using Bayesian spatial models. Methods: This ecological study was implemented in Tehran on the neighborhood level. Socioeconomic variables, risk factors, and health costs were extracted from the Equity Assessment Study conducted in Tehran. The data on CRC incidence were extracted from the Iranian population-based cancer registry. The Besag-York-Mollié (BYM) model was used to identify factors associated with the spatial distribution of CRC incidence. The software programs OpenBUGS version 3.2.3, ArcGIS 10.3, and GeoDa were used for the analysis. Results: The Moran index was statistically significant for all the variables studied (p<0.05). The BYM model showed that having a women head of household (median standardized incidence ratio [SIR], 1.63; 95% confidence interval [CI], 1.06 to 2.53), living in a rental house (median SIR, 0.82; 95% CI, 0.71 to 0.96), not consuming milk daily (median SIR, 0.71; 95% CI, 0.55 to 0.94) and having greater household health expenditures (median SIR, 1.34; 95% CI, 1.06 to 1.68) were associated with a statistically significant elevation in the SIR of CRC. The median (interquartile range) and mean (standard deviation) values of the SIR of CRC, with the inclusion of all the variables studied in the model, were 0.57 (1.01) and 1.05 (1.31), respectively. Conclusions: Inequality was found in the spatial distribution of CRC incidence in Tehran on the neighborhood level. Paying attention to this inequality and the factors associated with it may be useful for resource allocation and developing preventive strategies in atrisk areas.

Spatial Inequalities in the Incidence of Colorectal Cancer and Associated Factors in the Neighborhoods of Tehran, Iran: Bayesian Spatial Models

Mansori, Kamyar,Solaymani-Dodaran, Masoud,Mosavi-Jarrahi, Alireza,Motlagh, Ali Ganbary,Salehi, Masoud,Delavari, Alireza,Asadi-Lari, Mohsen The Korean Society for Preventive Medicine 2018 Journal of Preventive Medicine and Public Health Vol.51 No.1

Objectives: The aim of this study was to determine the factors associated with the spatial distribution of the incidence of colorectal cancer (CRC) in the neighborhoods of Tehran, Iran using Bayesian spatial models. Methods: This ecological study was implemented in Tehran on the neighborhood level. Socioeconomic variables, risk factors, and health costs were extracted from the Equity Assessment Study conducted in Tehran. The data on CRC incidence were extracted from the Iranian population-based cancer registry. The $Besag-York-Molli{\acute{e}}$ (BYM) model was used to identify factors associated with the spatial distribution of CRC incidence. The software programs OpenBUGS version 3.2.3, ArcGIS 10.3, and GeoDa were used for the analysis. Results: The Moran index was statistically significant for all the variables studied (p<0.05). The BYM model showed that having a women head of household (median standardized incidence ratio [SIR], 1.63; 95% confidence interval [CI], 1.06 to 2.53), living in a rental house (median SIR, 0.82; 95% CI, 0.71 to 0.96), not consuming milk daily (median SIR, 0.71; 95% CI, 0.55 to 0.94) and having greater household health expenditures (median SIR, 1.34; 95% CI, 1.06 to 1.68) were associated with a statistically significant elevation in the SIR of CRC. The median (interquartile range) and mean (standard deviation) values of the SIR of CRC, with the inclusion of all the variables studied in the model, were 0.57 (1.01) and 1.05 (1.31), respectively. Conclusions: Inequality was found in the spatial distribution of CRC incidence in Tehran on the neighborhood level. Paying attention to this inequality and the factors associated with it may be useful for resource allocation and developing preventive strategies in at-risk areas.