Distribution of heavy metals in the clastic fine-grained sediments of Gavkhuni playa lake (Southeast of Isfahan,Iran)   总被引：1，自引：1，他引：0  

Hamid Reza Pakzad  Mehrdad Pasandi  Hajar Rahimi 《Environmental Earth Sciences》2014,71(11):4683-4692

The sedimentary basin of Gavkhuni playa lake includes two sedimentary environments of delta and playa lake. These environments consist of mud, sand and salt flats. There are potentials for concentration of heavy metals in the fine-grained sediments (silt and clay) of the playa due to existence of Pb/Zn ore deposits, industrial and agricultural regions in the water catchment of Zayandehrud River terminating to this area. In order to study the concentration of heavy metals and the controlling factors on their distribution in the fine-grained sediments, 13 samples were taken from the muddy facies and concentration of the heavy metals were determined. The results showed that the heavy metal concentrations range in the sediments (in ppm) are Mn (395.5–1,040), Sr (100.4–725.76), Pb (14.66–91.06), Zn (23.59–80.9), Ni (37–73.66), Cu (13.83–29.83), Co (5.73–13.78), Ag (3.03–4.76) and Cd (2.3–5.5) in their order of abundances. The concentration of Ag is noticeable in the sediments relative to the average concentration of this element in mud sediments. The amounts of Pb and Zn are relatively high in all the samples in comparison with the other elements. The concentration of Ni is relatively high in the oxidized samples. The distribution of Pb is directly related to organic matter content of the sediments. The concentrations of Zn, Sr, Cu, Co and Cd in the samples of the playa are lower than those in the delta. The amount of illite is another factor influencing Zn and Pb concentrations. Sr is more concentrated in the sediments with the high content of calcium carbonate. The distribution pattern of Cu, Co, Pb and Mn resembles to that of the clay content of the sediments. The clay content shows positive correlations with Co, Cu and Mn concentrations and negative correlation with Ag. The Sr and Ag concentrations are positively correlated with the amount of CaCO₃. The amounts of Co, Cu, Ni and Mn show negative correlations with the calcium carbonate content. Pb and Co are noticeably correlated with Mn.  相似文献   

Investigation of surface and subsurface displacements due to multiple tunnels excavation in urban area     

Alireza Talebinejad  Hamid Chakeri  Mahdi Moosavi  Yılmaz Özçelik  Bahtiyar Ünver  Mehmet Ali Hindistan 《Arabian Journal of Geosciences》2014,7(9):3913-3923

Underground structures are currently widely used and are built as urbanism develops. The interactions between perpendicularly crossing and parallel tunnels in the Tehran region are investigated by using a full three-dimensional (3D) finite difference analysis with elastic-plastic material models. Special attention is paid to the effect of subsequent tunneling on the support system, i.e., the shotcrete lining and rock bolts of the existing tunnel. Eventually, as the tunnels are excavated at certain levels, the interaction between the tunnels will certainly have a significant influence on both stress distribution and consequently deformations. Since multilayer tunneling is a three-dimensional phenomenon in nature, 3D numerical solutions must be utilized for analyzing effect of perpendicularly crossing tunnels at various levels. As Tohid twin tunnels and Line 7 pass beneath the Line 4 metro tunnel, changes in stress distribution, deformations, and surface settlements are studied for various conditions and the results are presented in this paper. Consequently, it is shown that there is a significant interaction between tunnels that necessitate certain preventive measures to maintain a stable tunneling operation.  相似文献   

Brittleness Effect on Rock Fatigue Damage Evolution   总被引：1，自引：0，他引：1  

Hamid Reza Nejati  Abdolhadi Ghazvinian 《Rock Mechanics and Rock Engineering》2014,47(5):1839-1848

The damage evolution mechanism of rocks is one of the most important aspects in studying of rock fatigue behavior. Fatigue damage evolution of three rock types (onyx marble, sandstone and soft limestone) with different brittleness were considered in the present study. Intensive experimental tests were conducted on the chosen rock samples and acoustic emission (AE) sensors were used in some of them to monitor the fracturing process. Experimental tests indicated that brittleness strongly influences damage evolution of rocks in the course of static and dynamic loading. AE monitoring revealed that micro-crack density induced by the applied loads during different stages of the failure processes increases as rock brittleness increases. Also, results of fatigue tests on the three rock types indicated that the rock with the most induced micro-cracks during loading cycles has the least fatigue life. Furthermore, the condition of failure surfaces of the studied rocks samples, subjected to dynamic and static loading, were evaluated and it was concluded that the roughness of failure surfaces is influenced by loading types and rock brittleness. Dynamic failure surfaces were rougher than static ones and low brittle rock demonstrate a smoother failure surface compared to high brittle rock.  相似文献   

<Emphasis Type="Italic">3D</Emphasis> Modelling of Urban Area Using Synthetic Aperture Radar (SAR)     

Alireza Sharafzadeh  Ali Esmaeily  Maryam Dehghani 《Journal of the Indian Society of Remote Sensing》2018,46(11):1785-1793

Synthetic aperture radar (SAR) is a newly-developed remote sensing technology that works in all weather and independent of daylight. Recent satellite designs such as TerraSAR-x, which have resolutions of a couple of meters and sub-meters, have provided appropriate data for modelling and monitoring of urban areas. Image classification and height information extraction is possible considering the nature of SAR data. In this paper, a proper classification method for high-resolution SAR images has been used in urban areas. This classifier is based on statistical models. First, statistical models that are well adapted to urban SAR images are selected. Initial labelling is performed using the maximum likelihood method. A method based on Markov random fields is applied to improve the results by considering neighbourhood information. Meanwhile, topographic information is extracted using the phase difference obtained from SAR interferometry. After classification and height extraction, the homogeneous regions consisting of locations with similar objects are determined. The homogeneous region adjacency graph are generated using vectors containing classification information, extracted objects, height of pixels forming each region, and information on the neighbouring areas. Height and classification information are then merged by assigning height conditions based on the nature of objects and optimizing an energy function. The results obtained, including buildings, streets, and corner reflectors, are easily recognizable. The overall accuracy is improved from 57% in the initial classification to 95% in the employed procedure. Moreover, the accuracy of height estimation is about 2.74 m, which is acceptable for height estimations of buildings with more than one floor.  相似文献   

Investigation of SVM and Level Set Interactive Methods for Road Extraction from Google Earth Images     

Abolfazl Abdollahi  Hamid Reza Riyahi Bakhtiari  Mojgan Pashaei Nejad 《Journal of the Indian Society of Remote Sensing》2018,46(3):423-430

Currently, methods of extracting spatial information from satellite images are mainly based on visual interpretations and drawing the consequences by human factor, which is both costly and time consuming. A large volume of data collected by satellite sensors, and significant improvement in spatial and spectral resolution of these images require the development of new methods for optimal use of these data in order to produce rapid economic and updating road maps. In this study, a new automatic method is proposed for road extraction by integrating the SVM and Level Set methods. The estimated probability of classification by SVM is used as input in Level Set Method. The average of completeness, correctness, and quality was 84.19, 88.69 and 76.06% respectively indicate high performance of proposed method for road extraction from Google Earth images.  相似文献   

Trend analysis of the rainfall erosivity index at different time scales in Iran   总被引：2，自引：0，他引：2  

Seyed Hamid Reza Sadeghi  Zeinab Hazbavi 《Natural Hazards》2015,77(1):383-404

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An integrated artificial neural network model for the landslide susceptibility assessment of Osado Island,Japan   总被引：1，自引：0，他引：1  

Jie Dou  Hiromitsu Yamagishi  Hamid Reza Pourghasemi  Ali P. Yunus  Xuan Song  Yueren Xu  Zhongfan Zhu 《Natural Hazards》2015,78(3):1749-1776

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Origin and recharge mechanisms of groundwater in the upper part of the Awaj River (Syria) based on hydrochemistry and environmental isotope techniques   总被引：1，自引：0，他引：1  

N. M. Asmael  F. Huneau  E. Garel  H. Celle-Jeanton  P. Le Coustumer  A Dupuy  S. Hamid 《Arabian Journal of Geosciences》2015,8(12):10521-10542

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Peculiar motions of galaxy clusters: correlation function approach     

Naseer Iqbal  Tabasum Masood  Mubashir Hamid  Naveel Ahmad  Bari Maqbool 《Astrophysics and Space Science》2014,353(2):621-624

The correlation function theory on the basis of prescribed boundary conditions provides a deeper understanding in studying the dynamical parameters of galaxy clusters. The approach approximates that the moderate dense systems discussed by a two point correlation function is helpful for describing the dynamical nature of galaxy clusters. The projected theory of two point correlation function for point mass and extended mass structures can be used an alternative tool in measuring the average peculiar motion and temperature profile of galaxy clusters.  相似文献   

Fourier analysis of the light curves of eclipsing variables. XIXA:     

Hamid M. K. Al-Naimiy 《Astrophysics and Space Science》1978,53(1):3-11

The radiation of a charge rotating in a circle with the constant velocity (in the external magnetic field) in the isotropic plasma with random inhomogeneities of the electron density has been considered. A general expression is obtained for the radiation intensity at thenth harmonic, which is a generalization of the known Shott formula. In the ultra-relativistic case the conditions are clarified under which the inhomogeneity effect on the form of the spectrum of radiation from a particle is essential. An asymptotic formula is derived for the spectral intensity in the region of sufficiently low frequencies. The mechanism of transient radiation in this case is shown to prevail over the synchrotron one.  相似文献