Vector ionosphere modeling by vector spherical Slepian base functions     

Etemadfard  Hossein  Hossainali  Masoud Mashhadi 《GPS Solutions》2017,21(2):675-684

GPS Solutions - Ionosphere and its spatial and temporal gradients play an important role in positioning and navigation using global navigation satellite systems (GNSS). This study intends to...  相似文献   

Sensitivity analysis and accuracy assessment of the land transformation model using cellular automata     

Hossein Shafizadeh-Moghadam  Ali Asghari  Mohammad Taleai  Marco Helbich  Amin Tayyebi 《地理信息系统科学与遥感》2017,54(5):639-656

This study evaluates the effects of cellular automata (CA) with different neighborhood sizes on the predictive performance of the Land Transformation Model (LTM). Landsat images were used to extract urban footprints and the driving forces behind urban growth seen for the metropolitan areas of Tehran and Isfahan in Iran. LTM, which uses a back-propagation neural network, was applied to investigate the relationships between urban growth and the associated drivers, and to create the transition probability map. To simulate urban growth, the following two approaches were implemented: (a) the LTM using a top-down approach for cell allocation grounding on the highest values in the transition probability map and (b) a CA with varying spatial neighborhood sizes. The results show that using the LTM-CA approach increases the accuracy of the simulated land use maps when compared with the use of the LTM top-down approach. In particular, the LTM-CA with a 7 × 7 neighborhood size performed well and improved the accuracy. The level of agreement between simulated and actual urban growth increased from 58% to 61% for Tehran and from 39% to 43% for Isfahan. In conclusion, even though the LTM-CA outperforms the LTM with a top-down approach, more studies have to be carried out within other geographical settings to better evaluate the effect of CA on the allocation phase of the urban growth simulation.  相似文献   

Simulation of Power Production from Dry Geothermal Well Using Down-hole Heat Exchanger in Sabalan Field,Northwest Iran     

Younes Noorollahi  Saeid Mohammadzadeh Bina  Hossein Yousefi 《Natural Resources Research》2016,25(2):227-239

In this research, a simulation was performed for evaluating power production from an abandoned geothermal well as an enhanced geothermal system by injecting a secondary fluid. Abandoned wells, due to lack of fluid or very low transmissivity, are regarded among the low-to moderate-temperature resources that have the potential for heat production without any cost for deep drilling. Accordingly, they are taken as suitable sources of energy. In the present paper, an abandoned geothermal well at Meshkinshahr geothermal field in Sabalan district, northwestern Iran, with 3176 m depth was simulated. The bottom-hole temperature of 148 °C, as well as well casing size, and real thermal gradient for well were applied in the model. A 3D heat transfer simulation model was designed by considering a coaxial pipe as a down-hole heat exchanger between surrounding rocks of the well and injected fluid. Injected fluid to the well with specified pressure and temperature receives heat from rocks surrounding the well, until it reaches the bottom of the well and converts to vapor. The vapor returns to the surface from inner pipe with very low heat loss during its return. The inner pipe is isolated by a thin layer having a low heat conductivity to prevent heat loss from the returned fluid. It was observed that obtained heat in the well depends on temperature profile of the well, injection velocity, and fluid mass flow rate. The model results were optimized by selecting suitable parameters such as inlet injection speed and fluid flow rate to achieve the highest temperature of the fluid returned from the well. A binary power plant was also modeled to determine the extractable power using returned fluid as input using ammonia and isobutene, as working fluids in binary cycle. Finally, electric power of 270 kW was generated from well NWS3 using designed down-hole heat exchanger.  相似文献   

Wishart Derived Distance Based Clustering of Polarimetric SAR Images Using Support Vector Machines     

Hossein Aghababaee  Mahmod Reza Sahebi 《Journal of the Indian Society of Remote Sensing》2016,44(6):1003-1010

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Determining the groundwater potential recharge zone and karst springs catchment area: Saldoran region,western Iran     

Gholam Hossein Karami  Rahim Bagheri  Fahimeh Rahimi 《Hydrogeology Journal》2016,24(8):1981-1992

Assessing the groundwater recharge potential zone and differentiation of the spring catchment area are extremely important to effective management of groundwater systems and protection of water quality. The study area is located in the Saldoran karstic region, western Iran. It is characterized by a high rate of precipitation and recharge via highly permeable fractured karstic formations. Pire-Ghar, Sarabe-Babaheydar and Baghe-rostam are three major karstic springs which drain the Saldoran anticline. The mean discharge rate and electrical conductivity values for these springs were 3, 1.9 and 0.98 m³/s, and 475, 438 and 347 μS/cm, respectively. Geology, hydrogeology and geographical information system (GIS) methods were used to define the catchment areas of the major karstic springs and to map recharge zones in the Saldoran anticline. Seven major influencing factors on groundwater recharge rates (lithology, slope value and aspect, drainage, precipitation, fracture density and karstic domains) were integrated using GIS. Geology maps and field verification were used to determine the weights of factors. The final map was produced to reveal major zones of recharge potential. More than 80 % of the study area is terrain that has a recharge rate of 55–70 % (average 63 %). Evaluating the water budget of Saldoran Mountain showed that the total volume of karst water emerging from the Saldoran karst springs is equal to the total annual recharge on the anticline. Therefore, based on the geological and hydrogeological investigations, the catchment area of the mentioned karst springs includes the whole Saldoran anticline.  相似文献   

Comparison of SRM and WetSpa models efficiency for snowmelt runoff simulation     

Hamid Karimi  Hossein Zeinivand  Naser Tahmasebipour  Ali Haghizadeh  Mirhassan Miryaghoubzadeh 《Environmental Earth Sciences》2016,75(8):664

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Relationships between geological formations and groundwater chemistry and their effects on the concrete lining of tunnels (case study: Tabriz metro line 2)     

Mohammad Hossein Ghobadi  Mahnaz Firuzi  Ebrahim Asghari-Kaljahi 《Environmental Earth Sciences》2016,75(12):987

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Effect of Natural Zeolite and Cement Additive on the Strength of Sand   总被引：1，自引：1，他引：0  

Hossein Mola-Abasi  Behrouz Kordtabar  Afshin Kordnaeij 《Geotechnical and Geological Engineering》2016,34(5):1539-1551

It is widely known and well emphasized that the cemented sand is one of economic and environmental topics in soil stabilization. In some instances, a blend of sand, cement and other materials such as fiber, glass, nano particle and zeolite can commercially be available and effectively used in soil stabilization especially in road construction. In regard to zeolite, its influence and effectiveness on the properties of cemented sands systems has not been completely explored. Hence, in this study, based on an experimental program, it has been tried to investigate the potential of a zeolite stabilizer known as additive material to improve the properties of cemented sands. A total number of 216 unconfined compression tests were carried out on cured samples in 7, 28 and 90 days. Results show unconfined compression strength and failure properties improvements of cement sand specimens when cement replaced by zeolite at optimum proportions of 30 % after 28 days due to pozzolanic reaction. The rate of strength improvement is approximately 20–78 and 20–60 % for 28 and 90 days curing times respectively. The efficiency of using zeolite has been enhanced by increasing the cement content and porosity of the compacted mixture. The replacement of cement by natural zeolite led to an increase of the pH after 14 days. Chemical oxygen demand (COD) tests demonstrate that the materials with the zeolite mixture reveal stronger adsorptive capacity of COD in compare to cemented mixture. Scanning electron microscope images show that adding zeolite in cemented sand changes the microstructure (filling large porosity and pozzolanic reaction) that results in increasing strength.  相似文献   

Application of the Christensen Failure Criterion to Intact Rock     

Hossein Rafiei Renani  C. Derek Martin  Evert Hoek 《Geotechnical and Geological Engineering》2016,34(1):297-312

The Christensen criterion, originally introduced in materials science, has a simple mathematical form and uniaxial tensile and compressive strength as the only parameters, making it an attractive candidate for rock engineering purposes. In this study, the applicability of the criterion to rock materials is examined. Explicit equations for application of the criterion under biaxial, triaxial compression, triaxial extension, and polyaxial states of stresses are derived. A comprehensive strength data set including the results of tests on synthetic rock, chert dyke, Carrara marble and Westerly granite is utilized to examine the accuracy of the Christensen criterion to the failure of rock material. The two surprising findings about the Christensen criterion are the zero values of tensile strength and the very low slopes of the failure envelope obtained from fitting analyses for chert dyke and Westerly granite. It is shown that the two problems are interrelated and the values of tensile strength tend to zero to produce higher slopes. It is then mathematically proven that the maximum initial slope of the Christensen failure envelope is limited to 4 in triaxial compression and 2.5 in triaxial extension which is considerably lower than the slope of experimental data. The accuracy of the Christensen criterion was found to be significantly lower than the well-established Hoek–Brown criterion. The circular π-plane representations and brittle-to-ductile transition limits from the Christensen criterion are also inconsistent with the observed behavior of rocks.  相似文献   

Simulation of rainfall-runoff process using an artificial neural network (ANN) and field plots data     

Gholami  Vahid  Sahour  Hossein 《Theoretical and Applied Climatology》2022,147(1-2):87-98

Theoretical and Applied Climatology - Rainfall-runoff modeling is necessary for many hydrological studies, such as estimating peak discharges and designing hydraulic structures. The intensity and...  相似文献