124 research outputs found

    Numerical modeling and estimation of renewable energy of tidal current in Khoore Musa

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    In this article, two three-dimensional hydrodynamic and numerical models, COHERENS and BOM are used to investigate the renewable tidal energy in Khoore Musa. Firstly, the effect of 6 tidal constituents on regional hydrodynamic is estimated in 10 sigma levels in vertical and 250 resolution. The results of both models are verified with field data recorded by Iranian National Institute for Oceanography. It is found that the outcomes of COHERENS are more reliable but calibration is required. Whereas the accuracy of calibrated hydrodynamic module of COHERENS is approved, the energy of tidal currents is calculated. In this study, the current energy module is developed and set as a supplementary module. Hourly averaging of current energy during one month indicated that the maximum value recorded was more than 0.65 MWh. The maximum depth-integrated energy of this area was about 5 MWh. The best and more advantageous area to extract energy is a strait in the Middle-Bar with density of more than 300

    Study of temporal and spatial variations of physical parameters (temperature, salinity and density) trend of the Pozm Bay

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    Pozm bay Located in southern coast of Iran near Oman Sea, due to its relative calmness, low depth and being affected by the land substances is interesting to some aquatics species for reproduction and spending part of their growth period. In this research the seasonal variations of physical parameters trend of the Pozm pay was investigated during 9 periods since Oct 2011 till Aug 2012. The physical parameters of the sea water were measured by the CTD device in 17 stations from surface to seabed. These parameters are as follows: Temperature, Salinity, Density, Electrical conductivity, Sound velocity, Turbidity, and the Dissolved oxygen. According to the results of this research, the variations of the water temperature are following the air temperature and increase as the air temperature arises in hot seasons. Although due to the low depth of Pozm bay the formation of thermocline layer and water stratification are so low, weak stratification is formed in water column during hot months of the year. The entering flow of Oman Sea water into the Persian Gulf, which is less salty comparing to that of Persian Gulf, is maximized during late spring and minimized in winter and affects the salinity of Pozm bay water such that its rate is more during mild months than hot months. The variation of the density is influenced by water temperature and the salinity has no effect on them. The summer monsoon has a significant effect on the physical parameters of Pozm bay's water

    Marine energy extraction of waves and tidal currents in Chabahar Bay

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    Development of modern energies is one of the most important issues that all countries have focused on and have tried to find a new model in that respect. This study investigates various methods of estimating energies that are produced by wave and then it concludes that the best method is spectrum analysis using Fourier analysis. Using available data of year 1998 in Chabahar and applying a program which is produced in MATLAB environment, rate of producible energy in year 1998 is equal to 6.9 Kwh/m² and producible power of waves has been estimated to be 3.9 Kw/m² with the lowest rate of energy observed in winter and the highest rate of wave energy in summer. Probable cause of this phenomenon could be seasonal winds that blow in summer. According to the flowmetry report done by Ports and Maritime Organization in Chabahar, in Aw1 Station has divided its 9-meter distance below water surface into 7 cells, therefore, with considering 1×1m channels and assuming that flow in each channel has been changed steadily, tide flow energy has been estimated and average energy of Chabahar station has been obtained equal to 0.12 w/m^2 within two weeks. In the second way, using program written in MATLAB environment and calculating the surface under the chart, tide energy has been calculated equal to 0.19w/ m^2. According to the obtained results, producible energy of tidal current in Chabahar Gulf is very low and it is not economical

    Numerical modeling of polloution distribution in the Nayban bay

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    In this study COHERENS which is a three-dimensional hydrodynamic model was employed in order to model and survey dispersion of pollution in Nayband bay. In this model Navier-Stokes equation, continunity equation and transport equations of salinity and temperature in 3-D are solved. Cartesian coordinate for the horizontal and sigma coordinate with five layers was used for the vertical profile. Monthly mean atmospheric parameters and 4 major tidal components (M2, S2, O1, and K1) of the bay were used as the inputs of the model. In this model, uniform grid of 79*100 was used. Once the model was adjusted and the data inserted, the model was run for the bay. Then tidal currents were validated with field observation which resulted in prediction of horizontal dispersion of pollution in different layers. The results showed that dispersion is highly affected by tidal currents. These results can be applied to predict dispersion of pollution in Nayband bay

    The study of layering structure of outlfow from the Persian Gulf to Gulf of Oman and it's impact on propagation of sound with acoustic sources about outflow intrusion at spring

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    In this study, variations of field data such as temperature, salinity and sound of speed in horizontal and across transects of the Gulf of Oman were analyzed using CTD data acquired by international project, Joint Global Ocean Flux Study (JGOFS) during the spring of 1996. Results indicate that at all sections, at depths between 120 m to 276m in Gulf of Oman to 60 °E, finestructures were found; this indicates mixing with surrounding waters by thermohaline intrusions. These thermohaline intrusions caused temperature and salinity inversion that causes inversion of sound speed profile. Thickness inversion at the stations near the Strait of Hormuz is about 156 m and at stations far from the Strait of Hormuz (near the Oman of Sea) is about 80m. By previous studies, this outflow intrusion causes the internal waves in the Gulf of Oman. These results suggest that formation of intrusion depends on the intermittent outflow through the Strait of Hormuz. In this survey, high salinity water and high temperature water masses spread into the Persian Gulf at an intermediate level, in the Gulf of Oman. In this research, the acoustic propagation characteristics (transmission loss, amplitude of signal and travel time of signal) up, below and into, of the outflow intrusion were assessed based on the output of a range-dependant acoustic model and range independent acoustic model. In general, the occurrence of this thermohaline intrusion was found to alter the propagation characteristics

    Investigation on wave energy in Amirabad seaport of Caspian Sea using SWAN model results

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    In this study, SWAN numerical model used to modeling waves and obtain the significant wave height in range of Amirabad seaport of Caspian Sea. To do this, first, a general model to modeling the wave height in the entire Caspian Sea was built. Then the boundary conditions obtained from the general model, by using the NEST operation of SWAN model, modeling the local with higher magnification in the area Amirabad Seaport was used. The local models built in the Amirabad, was calibration and verification with waves profile data recorded by buoys deployed in that area. Comparison the results with data measured by the Amirabad buoy shows that modeling done in this area had a good accuracy. Then running the SWAN model for three years and Obtained significant wave height in the desired location. Finally the wave energy obtained from significant wave height

    Study of tidal components amplitude distribution in the Persian Gulf, Gulf of Oman and Arabian Sea using numerical simulation

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    Tide is one of the most regular changes of seas and ocean levels which are offering particular importance due to the influence on the flow pattern in tidal zone. According to engineering needs and environmental protection issues in industrial-economic zone of Persian Gulf, Strait of Hormuz and Gulf of Oman, knowing tidal characteristics of this region is very important. Therefore FVCOM (a three-dimensional ocean model) was used in barotropic mode to stimulate the tidal amplitude in a wide region comprising Persian Gulf, Strait of Hormuz, Gulf of Oman and Arabian Sea. Finite volume method is applied in this model to discretize the hydrodynamic equations on triangular mesh. Uniform computational mesh is used with a resolution of 5 km in the model and one minute bathymetry data has been interpolated on this mesh. The constant values of eight diurnal and semidiurnal tidal components are prescribed along the open ocean boundary. After applying harmonic analysis on the model outputs in desired stations, the achieved amplitude of this analysis compared with results which are obtained from the analysis on the available measurement data in these stations to validate the model results. According to the measurement data and model results in these stations, meanwhile identifying the four main tidal components, the amplitude pattern of these components was determined in the whole domain. Also, by using amplitude of main components and estimating of F factor, the type of tide was predicted in the study area. According to the results obtained in this research, four types of diurnal, semidiurnal, mixed diurnal and mixed semidiurnal tides are seen in the Persian Gulf. In other areas, the tide will be mixed semidiurnal. Moreover, studying the maximum amounts of tidal velocity in the study area shows that the amount of this velocity in the Gulf of Oman and Arabian Sea is less than 0.1 m/s

    Aspergillosis of central nervous system in patients with leukemia and stem cell transplantation: a systematic review of case reports

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    Background: Aspergillosis of Central Nervous System (CNS) is a highly lethal infection in patients with leukemia and Stem Cell Transplantation (SCT). Methods: Case reports of CNS aspergillosis in patients with leukemia and SCT published between 1990 and August 2020 were gathered using a structured search through PubMed/Medline. Results: Sixty-seven cases were identified over the searches of the PubMed bibliographic database and then, 59 cases were included in the final analysis. Europe had the largest share of cases at 57.6 (34 reports), followed by Americas and Asia. Affected patients were predominantly males (58.6) and the mean age of the patients was 36.1 years, while 62.7 of the patients were under the age of 50 years. The most common leukemia types include Acute Lymphoblastic Leukemia (ALL), Chronic Lymphocytic Leukemia (CLL), and Acute Myeloid Leukemia (AML) at 43.4, 27.4, and 23.5, respectively. Furthermore, stem cell transplantation was reported in 11 cases. The overall mortality was 33; however, the attributable mortality rate of CNS aspergillosis was 24.5. Altered mental status, hemiparesis, cranial nerve palsies, and seizures were the clearest manifestations of infection and lung involvement reported in 57 of the patients. Histopathologic examination led to the diagnosis of infection in 57 of the patients followed by culture (23.7), galactomannan assay (8.5), and molecular method (3.3). Amphotericin B and voriconazole were the most frequently used drugs for infection treatment. Good results were not obtained in one-third of the patients treated by voriconazole. Finally, neurosurgical intervention was used for 23 patients (39). Conclusion: CNS aspergillosis is a rapidly progressive infection in leukemic patients. Thus, these patients should be followed up more carefully. Furthermore, management of induction chemotherapy, use of different diagnostic methods, and use of appropriate antifungal can lead to infection control. © 2021, The Author(s)
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