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191.
Neissi Lamya Golabi Mona Albaji Mohammad Naseri Abd Ali 《Theoretical and Applied Climatology》2022,147(1-2):701-716
Theoretical and Applied Climatology - Precise calculations for determining the water requirements of plants and the extent of evapotranspiration are crucial in determining the volume of water... 相似文献
192.
Climatic Change - Changes in precipitation pattern can lead to widespread impacts across natural and human systems. This study assesses precipitation variability as well as anthropogenic and... 相似文献
193.
Hamid Reza Nejati Morteza Ahmadi Hamid Hashemolhosseini Mohammad Hayati 《Geotechnical and Geological Engineering》2012,30(5):1137-1146
Ground surface vibration produced by moving train is one of the most important aspects in urban areas. The purpose of this study is the probabilistic analysis of ground surface vibration, which is generated by metro transportations. For this reason, Tehran metro line 4 is considered as a case study. In this paper, at first, a new procedure is used to simulate train dynamic load. In the second step, based on the variation of geomechanical properties and train characteristics in Tehran metro line 4, more than 60 numerical models are simulated. The results of numerical simulations are analyzed by multivariate statistical technique and an equation for prediction of peak particle velocity (PPV) in the ground surface is presented. In the next step, probabilistic analysis is done using Monte Carlo Simulation (MCS). Finally, sensitivity of input data on ground surface vibration is discussed and the impact of geomechanical properties and train characteristics on the surface vibration is considered. Based on the probabilistic analysis, PPV in the surface region of Tehran metro line 4 is <2.76?mm/s with 95?% probability. 相似文献
194.
Gold Deposits in the Sanandaj–Sirjan Zone: Orogenic Gold Deposits or Intrusion‐Related Gold Systems?
Most of the known large gold deposits in Iran are located along the Sanandaj–Sirjan Zone, western Iran, which hosts a wide range of gold deposit types. Gold deposits in the belt, hosted in upper Paleozoic to upper Mesozoic volcano‐sedimentary sequences of lower greenschist to lower amphibolite metamorphic grade, appear to represent mainly orogenic and intrusion‐related gold deposit types. The largest resource occurs at Muteh, with smaller deposits/occurrences at Zartorosht, Qolqoleh, Kervian, Qabaqloujeh, Kharapeh, and Astaneh. Although a major part of the gold deposits in the Sanandaj–Sirjan Zone are related to metamorphic devolatilization, some deposits including Muteh and Astaneh are related to short‐lived disruptions in an extensional tectonic regime and are associated with magma generation and emplacement. The age of gold ore formation in the orogenic gold deposits is Late Cretaceous to Tertiary, reflecting peak‐metamorphism during regional Cretaceous–Paleocene convergence and compression. The Oligocene to Pliocene age of most intrusion‐related gold systems is consistent with the young structural setting of the gold ore bodies; these deposits are sequestered along normal faults, correlated with Middle to Late Tertiary extensional tectonic events. This relationship is comparable to the magmatic‐metallogenetic evolution of the Urumieh‐Dokhtar magmatic arc, where the number of different types of gold‐copper deposits and the magnitude of the larger ones followed development of a magmatic arc. The appropriate explanation may be related to two different stages of gold mineralization consisting of a first compressional phase during the Late Cretaceous to Early‐Middle Tertiary, which is related to orogenic gold mineralization in the Qolqoleh, Kervian, Qabaqloujeh, Kharapeh, and Zartorosht deposits, and the extensional phase during the Eocene to Pliocene that is recognized by young intrusion‐related gold mineralization in the Muteh and Astaneh deposits. 相似文献
195.
The gravitational signal of the upper mantle density structures is investigated in the refined gravity data which are corrected for the gravitational contributions of the crust density structures and the Moho geometry. The gravimetric forward modeling is applied to compute these refined gravity data globally on a 1 × 1 arcdeg grid using the global geopotential model (EGM2008), the global topographic/bathymetric model (DTM2006.0) including the ice-thickness data, and the global crustal model (CRUST2.0). The characteristics of the upper mantle density structures are further analyzed in association with the Moho parameters (i.e., Moho depths and density contrast). The 1 × 1 arcdeg global data of the Moho parameters are estimated by applying the combined least-squares approach based on solving Moritz’s generalization of the Vening–Meinesz inverse problem of isostasy. The refined gravity data exhibit mainly the mantle lithosphere structures attributed to the global mantle convection. A significant correlation found over oceans between the refined gravity data and the Moho density contrast is explained by the increasing density of the oceanic lithosphere with age. Despite the lithosphere structures attributed to the global mantle convection are confirmed also in the refined gravity data over continents, the significant correlation between the refined gravity data and the Moho parameters is in this case absent. Instead, the significant proportion of lateral variations of the Moho density contrast within the continental lithosphere is attributed to the depth-dependant density changes due to pressure and thermal gradient. 相似文献
196.
A. Janalizadeh Choobbasti Mohammad Javad Vahdatirad M. Torabi S. Firouzian A. Barari 《Arabian Journal of Geosciences》2012,5(4):545-554
Paying special attention to geotechnical hazards such as liquefaction in huge civil projects like urban railways especially in susceptible regions to liquefaction is of great importance. A number of approaches to evaluate the potential for initiation of liquefaction, such as Seed and Idriss simplified method have been developed over the years. Although simplified methods are available in calculating the liquefaction potential of a soil deposit and shear stresses induced at any point in the ground due to earthquake loading, these methods cannot be applied to all earthquakes with the same accuracy, also they lack the potential to predict the pore pressure developed in the soil. Therefore, it is necessary to carry out a ground response analysis to obtain pore pressures and shear stresses in the soil due to earthquake loading. Using soil historical, geological and compositional criteria, a zone of the corridor of Tabriz urban railway line 2 susceptible to liquefaction was recognized. Then, using numerical analysis and cyclic stress method using QUAKE/W finite element code, soil liquefaction potential in susceptible zone was evaluated based on design earthquake. 相似文献
197.
Comparative study on the equivalent linear and the fully nonlinear site response analysis approaches 总被引:1,自引:0,他引:1
S. Majdeddin Mir Mohammad Hosseini Mojdeh Asadollahi Pajouh 《Arabian Journal of Geosciences》2012,5(4):587-597
Seismic site effect has been a major issue in the field of earthquake engineering due to the large local amplification of the seismic motion. This paper presents the importance of an appropriate soil behavior model to simulate earthquake site response and gives an overview of the field of site response analysis. Some of the well-known site response analysis methods are discussed. The objective of this paper is to investigate the influences of nonlinearity on the site response analysis by means of a more precise numerical model. In this respect, site responses of four different types of one-layered soil deposit, based on various shear wave velocities with the assumption of linear and rigid base bedrock, were analyzed by using the equivalent linear and fully nonlinear approaches. Nonlinear analyses?? results were compared with those of the linear method, and both of the similarities and differences are discussed. It is concluded that in the case of nonlinearity of soil under strong ground motions, 1-D equivalent linear modeling overestimates the amplification patterns in terms of absolute amplification level, and cannot correctly account for resonant frequencies and hysteric soil behavior. Therefore, more practical and appropriate numerical techniques for ground response analysis should be surveyed. 相似文献
198.
A detailed geophysical investigation in the form of electrical resistivity tomography (ERT) was carried out using the SYSCAL Pro Unit at two locations with a dipole?Cdipole configuration in one of the private farms in Diriyah area of Riyadh, Saudi Arabia with the purpose of delineating the approximate depth of the water-bearing formations. The survey helped in delineating a superficial moist zone at the first site which was mainly due to the seepage from surface water pipes used for irrigating the date palms. At the second site, a potential water-bearing zone was detected starting from a depth of 23 to 46?m. However, an already existing bore well in close vicinity of the site of the second survey showed a water table depth of 85?m, indicating the presence of a layered aquifer. Finally, it was concluded that a shallow bore well drilled up to a depth of 50?C60?meters would be able to tap the water resources of shallow water-bearing horizon discovered at the second site during the survey; however, the yield of the bore well might not be sustainable over a longer period of time. The survey at the first site did not show any promising groundwater potential up to the investigated depth which was around 70?m. The study confirms the usage of ERT surveys for exploring sources of freshwater supplies in arid regions. 相似文献
199.
Comparison of artificial neural network and multivariate linear regression methods for estimation of daily soil temperature in an arid region 总被引:5,自引:0,他引:5
Hossein Tabari Ali-Akbar Sabziparvar Mohammad Ahmadi 《Meteorology and Atmospheric Physics》2011,110(3-4):135-142
Soil temperature (T S) strongly influences a wide range of biotic and abiotic processes. As an alternative to direct measurement, indirect determination of T S from meteorological parameters has been the focus of attention of environmental researchers. The main purpose of this study was to estimate daily T S at six depths (5, 10, 20, 30, 50 and 100?cm) by using a multilayer perceptron (MLP) artificial neural network (ANN) model and a multivariate linear regression (MLR) method in an arid region of Iran. Mean daily meteorological parameters including air temperature (T a), solar radiation (R S), relative humidity (RH) and precipitation (P) were used as input data to the ANN and MLR models. The model results of the MLR model were compared to those of ANN. The accuracy of the predictions was evaluated by the correlation coefficient (r), the root mean-square error (RMSE) and the mean absolute error (MAE) between the measured and predicted T S values. The results showed that the ANN method forecasts were superior to the corresponding values obtained by the MLR model. The regression analysis indicated that T a, RH, R S and P were reasonably correlated with T S at various depths, but the most effective parameters influencing T S at different depths were T a and RH. 相似文献
200.
Mohammad J. Tourian Johannes Riegger Nico Sneeuw Balaji Devaraju 《Studia Geophysica et Geodaetica》2011,55(4):627-640
Gravity measurements within the Gravity Recovery and Climate Experiment (GRACE) provide a direct measure of monthly changes
in mass over the Earth’s land masses. As such changes in mass mainly correspond to water storage changes, these measurements
allow to close the continental water balance on large spatial scales and on a monthly time scale within the respective error
bounds. When quantifying uncertainties, positive and negative peaks are detected in GRACE aggregated monthly time series (from
different data providers) that do not correspond to hydrological or hydro-meteorological signals. These peaks must be interpreted
as outliers, which carry the danger of signal degradation. In this paper an algorithm is developed to identify outliers and
replace them with hydrologically plausible values. The algorithm is based on a statistical approach in which hydrological
and hydro-meteorological signals are used to control the algorithm. The procedure of outlier detection is verified by evaluating
catchment based aggregated GRACE monthly signals with ground truth from hydrology and hydro-meteorological signals. The results
show improvement in the correlation of GRACE versus hydrometeorological and hydrological signals in most catchments. Also,
the noise level is significantly reduced over 255 largest catchments. 相似文献