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Search Results: 1 - 10 of 2591 matches for " Mehdi Behdarvandi Askar "
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Investigating the Effect of Relative Width on Momentum Transfer between Main Channel and Floodplain in Rough Rectangular Compound Channel Sunder Varius Relative Depth Condition  [PDF]
Shima Bahadori, Mehdi Behdarvandi Askar
Open Journal of Geology (OJG) , 2016, DOI: 10.4236/ojg.2016.64020
Abstract: Compound section is referred to a section the surface of which is made of several sub-sections with different flow characteristics. The difference in the hydraulic and geometry characteristics causes a complexity in flow hydraulic and creates an interaction between the main channel and floodplains, resulting in an apparent shear stress and a transverse momentum transfer. The amount of such a stress plays an important role in many river engineering measures[1]. Due to the flow complexity, the common approximate analytical methods are not enough to identify the flow profile. The FLOW3D Software with its great features in three-dimensional analysis of flow field is used as a tool to investigate the shear stress in a direct symmetrical compound rectangular channel. After the simulation of models, it is found that an increase in the relative width and relative depth parameters decreases the percentage of apparent shear stress and an increase in the relative roughness causes it to be increased[2].
Modeling the Pressure Distribution and the Changes of Water Level around the Offshore Platforms Exposed to Waves, Using the Numerical Model of Flow 3D  [PDF]
Milad Rashidinasab, Mehdi Behdarvandi Askar
Computational Water, Energy, and Environmental Engineering (CWEEE) , 2017, DOI: 10.4236/cweee.2017.61008
Abstract: The humans’ need to use the oceans for exploration and extraction of oil has led to the development of engineering science in the field of offshore structures. Since it’s important to examine the offshore structures from different aspects and perspectives, we would have to evaluate many different parameters about them. So categorizing these parameters can help to perform their related analysis with more accuracy and more details. Due to the efficient force it exerts on the structure, the pressure distribution around every marine or hydraulic structure has a significant importance, and it even accounts for one of the dominant issues in designing and building of such structures. In the present study, an oil platform located in Phase 15 of South Pars oil fields, located in the Persian Gulf waters, has been analyzed using the FLOW 3D software. The outputs indicate that the pressure of water is distributed almost hydrostatically with the depth, and its maximum reaches 0.6 MPa at the bottom.
Comparison of the Effect of Tetrapod Block and Armor X block on Reducing Wave Overtopping in Breakwaters  [PDF]
Omid Nourani, Mehdi Behdarvandi Askar
Open Journal of Marine Science (OJMS) , 2017, DOI: 10.4236/ojms.2017.74033
As the Armor shape has a significant effect on the reduction of wave overtopping, this study compares the performance of various shapes of concrete armored blocks of X block and Tetrapod as the most suitable armors. In this study, a three-dimensional numerical model was used for simulation of the effects of waves on the armors of Tetrapod and X Block breakwaters. In this regard, in order to calibrate the numerical model, a sample of conventional stone armor has been selected and using available experimental data on the design of armor such as wave overtopping, wave height, period of waves and energy density of the required spectral range of wave verification was conducted on a numerical model. In this regard, it is necessary to calibrate all the conditions of the model including boundary conditions, numerical modeling, initial conditions, numerical solvers and other parameters in the numerical model and simulation error rate is determined. The maximum error of the numerical model for the relative height values of the impact waves on the structure of breakwater is 7.87% for different conditions. Accordingly, the maximum error of the numerical model in determining overtopping values is 7.81%. The average fluctuation value of overtopping in the X block armor has dropped by about 31% compared to the tetrapod armor.
Evaluation of Sediment Transport in the Naiband Gulf Area Using Mike21  [PDF]
Parviz Soltani, Mehdi Behdarvandi Askar, Hossein Bahrami, Sadegh Haghighi Pour
Open Journal of Geology (OJG) , 2017, DOI: 10.4236/ojg.2017.72012
Abstract: Naiband Gulf is part of Naiband National Park known as Iran’s first marine national park. It is Iran’s most important habitats in the northern Persian Gulf due to mangrove forests, coral community, and community of marine animals. The study examines the sediment transport in the Naiband Gulf and around it, where to achieve this. First, the required data including coastline information, sediment profile, and bathymetry information and waves are obtained. Then by Mike21, 2011 Version models, it was attempted to simulate waves and currents due to it in the coastal zone to determine the rate and direction of sediment transport in the Naiband Gulf area. The results obtained in this study indicate that the majority of sediment transport directions on both sides of the gulf have been internal. The existence of structures in the north and south of the Gulf has reduced alongshore sediment flows and sedimentation, especially in the south of the gulf that is a serious threat to corals.
Investigation Flow Depth and Flow Speed Changes in the Karun River  [PDF]
Mehrab Yusefi Hagivar, Mehdi Behdarvandi Askar, Shariat Moalemi
Open Journal of Marine Science (OJMS) , 2017, DOI: 10.4236/ojms.2017.72021
Abstract: In the present study, the Karun River in Khuzestan province in Iran is that is somehow considered the river with the most water in the country was examined. To examine the depth and speed of the flow, which undoubtedly have the greatest impact on the environment and ecosystem of the river, two-dimensional simulation by CCHE2D model was used. In this study, it was observed that, firstly, the changes of depth and velocity along the river have good coordination and the highest changes were observed in the meander and arches. Moreover, due to using two-dimensional model, there is the possibility of examining changes of parameters in the longitudinal and transverse direction that shows the two-dimensional model is an efficient and powerful model in studying river flows.
Modeling of the Changes in Flow Velocity on Seawalls under Different Conditions Using FLOW-3D Software  [PDF]
Maryam Deilami-Tarifi, Mehdi Behdarvandi-Askar, Vahid Chegini, Sadegh Haghighi-Pour
Open Journal of Marine Science (OJMS) , 2016, DOI: 10.4236/ojms.2016.62026
Abstract: Seawalls are among protective structures that are constructed for decreasing the level of wave force and/or protecting from other structures. In this regard, more accurate investigation of these structures takes great importance from different perspectives. This research investigates the?change of the velocity on seawall crown by considering the obstacles in different layouts and slopes.?FLOW-3D has been used in this research for modeling. The results of the modeling show that the existence of obstacles has a determinative role in decreasing flow rate in the crown of seawalls. Also, as it was expected, the slope factor on upstream seawalls is very determinative in decreasing this rate such that the lowest velocity on the wall occurs in D-state layout and the slope of 45°.
Nonlinear Differential Equation of Macroeconomic Dynamics for Long-Term Forecasting of Economic Development  [PDF]
Askar Akaev
Applied Mathematics (AM) , 2018, DOI: 10.4236/am.2018.95037
In this article we derive a general differential equation that describes long-term economic growth in terms of cyclical and trend components. Equation is based on the model of non-linear accelerator of induced investment. A scheme is proposed for obtaining approximate solutions of nonlinear differential equation by splitting solution into the rapidly oscillating business cycles and slowly varying trend using Krylov-Bogoliubov-Mitropolsky averaging. Simplest modes of the economic system are described. Characteristics of the bifurcation point are found and bifurcation phenomenon is interpreted as loss of stability making the economic system available to structural change and accepting innovations. System being in a nonequilibrium state has a dynamics with self-sustained undamped oscillations. The model is verified with economic development of the US during the fifth Kondratieff cycle (1982-2010). Model adequately describes real process of economic growth in both quantitative and qualitative aspects. It is one of major results that the model gives a rough estimation of critical points of system stability loss and falling into a crisis recession. The model is used to forecast the macroeconomic dynamics of the US during the sixth Kondratieff cycle (2018-2050). For this forecast we use fixed production capital functional dependence on a long-term Kondratieff cycle and medium-term Juglar and Kuznets cycles. More accurate estimations of the time of crisis and recession are based on the model of accelerating log-periodic oscillations. The explosive growth of the prices of highly liquid commodities such as gold and oil is taken as real predictors of the global financial crisis. The second wave of crisis is expected to come in June 2011.
Olfactory Dysfunction in Persian patients suffering from Parkinson’s disease
Akbar Soltanzadeh,Mehdi Shams,Hamid Noorolahi,Askar Ghorbani
Iranian Journal of Neurology , 2011,
Abstract: Background: Looking in literature reveals that aging is accompanied by olfactory dysfunction and hyposmia/anosmia is a common manifestation in some neurodegenerative disorders. Olfactory dysfunction is regarded as non-motor manifestations of Parkinson disease (PD). The main goal of this study was to examine the extent of olfactory dysfunction in Persian PD patients.Methods: We used seven types of odors including rosewater, mint, lemon, garlic which were produced by Barij Essence Company in Iran. Additionally, coffee and vinegar were used. Subjects had to distinguish and name between seven previously named odors, stimuli were administered to each nostril separately.Results: Totally, 92 patients and 40 controls were recruited. The mean (standard deviation) (SD) age patients was 64.88 (11.30) versus 61.05 (7.93) in controls. The male: female ratio in patients was 50:42 versus 22:18 in control group. Also, mean UPDRS score (SD) in patients was 24.42 (5.08) and the disease duration (SD) was 3.72 (3.53). Regarding the number of truly detected odors, there were a significant higher number of correct identified odors in control group in comparison with the PD patients. Furthermore, there was a significant negative correlation between number of correct diagnosed smells and UPDRS (Pearson Correlation= -0.27, P=0.009); conversely, no significant correlation between the duration of Parkinson disease and number of correct diagnosed smells (P>0.05).Conclusion: smelling dysfunction is a major problem in Persian PD patients and it requires vigilant investigation for the cause of olfactory dysfunction exclusively in elder group and looking for possible PD disease.
Development of consumer lending in Kazakhstan under influence of world financial crisis
Askar Konakbaev
Perspectives of Innovations, Economics and Business , 2009,
Abstract: The paper observes the growth path of bank lending and in particular consumer loans in Kazakhstan. Consumer lending in Kazakhstan is steadily increasing and this niche remains attractive for commercial banks. However, the world financial crisis has complicated for banks the possibility of attraction of foreign credits to finance various investment and business projects in country. Financial crisis resulted decrease in growth rate of aggregate and consumer loans of commercial banks.
Result of subsoil irrigation research of alfalfa grown for green feed in Volgo-Akhtubinskaya flood plant
Akhmedov Askar
Journal of Agricultural Sciences , 2008, DOI: 10.2298/jas0802113a
Abstract: Relevance of subsoil irrigation usage for growing feed crops on alluvial meadow soils is shown. Distribution of pjezometric pressure, along the water emitter line during the irrigating period, is analyzed. Formation of moisture patterns in the soil regarding the quantities of irrigating water and emitters design are considered. In order to define the characteristics of moisture patterns in the soil, depending on the quantities of irrigating water, the ratios of vertical water spreading Kv and forms Kf are calculated. Expediency of usage low irrigating rates is substantiated. As a result of research, mathematical relations were derived in order to define water outlays in the emitters made of pottery tubes with diameter 50 mm under water pressure at the line 0.1…0.7 m. It is determined that usage of subsoil irrigation allows increase of commercial crop harvest, significantly save water resources, labour and energy comparing to sprinkling.
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