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11.
One of the main problems in reservoirs is sedimentation which reduces the operating life of dams if a proper plan and analysis method are not in place.The techniques to manage sediment in reservoirs include several sustainable management techniques that route sediment through or around the reservoir.One of the main economical methods in arid and semi-arid regions is pressurized flushing using moderate drawdown of the water level of the reservoir to evacuate sediment deposited behind dams.In the current study,the effect of a new structure called a dendritic bottomless extended(DBE)outlet structure at three angles of 30°,45°,and 60°on pressurized flushing efficiency was investigated.Consequently,45 experiments were designed for three discharge rates (Qo),three sediment levels(Hs),four types of structure,and a no-structure condition(reference test).The results indicated that the DBE structure with a 30°angle between the branches,a sedimentary dimensionless index of Hs/Do=4.59,and a flow dimensionless index of Qo=/√gD05=1:43(where g is the acceleration of gravity and Do is the diameter of the bottom outlet)lead to 10-fold increase in the sediment flushing cone dimensions and sediment removal efficiency compared to the results of the reference test.Finally,according to a statistical analysis of the results,a dimensionless equation for calculating the sediment flushing cone dimensions was developed for the tested sediment characteristics. 相似文献
12.
Majid Ehteshami Richard C. Peralta Hubert Eisele Howard Deer Terry Tindall 《Ground water》1991,29(6):862-868
13.
General conservation equations for multi-phase systems: 3. Constitutive theory for porous media flow
Equations which describe single phase fluid flow and transport through an elastic porous media are obtained by applying constitutive theory to a set of general multiphase mass, momentum, energy, and entropy equations. Linearization of these equations yields a set of equations solvable upon specification of the material coefficients which arise. Further restriction of the flow to small velocities proves that Darcy's law is a special case of the general momentum balance. 相似文献
14.
Mashallah Khamehchiyan Morteza Rahimi Dizadji Majid Esmaeili 《Geomechanics and Geoengineering》2014,9(1):63-71
Earthwork and surface excavation activities play an important role in construction projects. Selecting the best technique to loosen the overburden material within the surface excavation in open mining and geotechnical projects is of great importance from economical and technical viewpoints. Surface excavation includes direct digging, ripping and blasting. To select the most effective method and plan for excavation, geotechnical investigation is very important. It is also a big help in avoiding conflict between contractors and clients when they do not reach mutual agreement regarding the price of rock and soil excavation. There are many engineering classification systems used to assess rock masses for excavation purposes. All of these systems consider several geotechnical parameters to assess the earth masses. This study reviews these systems and then offers a new categorization based on the Rock Mass index (RMi) classification system and block volume to assess excavation in rock masses. The original dataset was obtained from the literature review as well as the surface excavation in Upper Gotvand dam and Hydro Power Plant (HPP). The offered system was also validated through the data extracted from the surface excavation in Sardasht dam and HPP in Iran. 相似文献
15.
Seyedeh Belin Tavakoly Sany Rosli Hashim Aishah Salleh Omid Safari Ali Mehdinia Majid Rezayi 《Environmental Earth Sciences》2014,71(10):4319-4332
Sediment samples collected from the West Port, the west coastal waters of Malaysia, were analyzed by standard methods to determine the degree of hydrocarbon contamination and identify the sources of polyaromatic hydrocarbons (PAHs). Concentrations of PAHs in the port sediments ranged from 100.3 to 3,446.9 μg/kg dw. The highest concentrations were observed in stations close to the coastline, locations affected by intensive shipping activities and industrial input. These were dominated by high-molecular-weight PAHs (4–6 rings). Source identification showed that PAHs originated mostly pyrogenically, from the combustion of fossil fuels, grass, wood, and coal or from petroleum combustion. Regarding ecological risk estimation, only station 7 was moderately polluted, the rest of the stations suffered rare or slight adverse biological effects with PAH exposure in surface sediment, suggesting that PAHs are not considered as contaminants of concern in the West Port. 相似文献
16.
This paper describes the application of a well-known multi-criteria decision-making technique, called preference ranking organization method for enrichment evaluation (PROMETHEE II), in combination with fuzzy analytical hierarchy process (FAHP), as a weighting technique to explore landslide susceptibility mapping (LSM). To this end, eight landslide-related geodata layers of the Minoo Dasht located in the Gorgan province of Iran, involving slope, aspect, distance to river, drainage density, distance to fault, mean annual rainfall, distance to road and lithology have been integrated using the PROMETHEE II enhanced by FAHP technique. Afterward, the receiver operating characteristics (ROC) curves for the proposed LSM were drawn using an inventory of landslides containing 83 recent and historic landslide points, and the area under curve = 0.752 value was calculated accordingly. Additionally, to further verify the practicality of such susceptibility map, it was also evaluated against the landslide inventory using simple overlay. The outcome was that about 11 % of the occurred landslide points fall into the very high susceptibility class of the LSM, but approximately 52 % of them indeed fall into the high and very high susceptibility zones together. Also, it resulted that no recorded landslide occurred in the zone of very low susceptibility. According to the results of the ROC curves analysis and simple overlay evaluation, the produced map has exhibited good performance. 相似文献
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19.
Siahsarani Amir Karami Khaniki Ali Aliakbari Bidokhti Abbas-Ali Azadi Majid 《Ocean Science Journal》2021,56(3):225-240
Ocean Science Journal - A storm surge is a complex phenomenon in which current, tide, and waves interact with each other. Even if the wind is the main force of driving the surge, waves and tide are... 相似文献
20.
Mohammady Majid Moradi Hamid Reza Zeinivand Hossein Temme A.J.A.M. Yazdani Mohammad Reza Pourghasemi Hamid Reza 《Theoretical and Applied Climatology》2018,133(1-2):459-471
Theoretical and Applied Climatology - Land use change is an important determinant of hydrological processes and is known to affect hydrological parameters such as runoff volume, flood frequency,... 相似文献