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排序方式: 共有109条查询结果,搜索用时 15 毫秒
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R. Fatemitalab M. Zare S. Kardar 《International Journal of Environmental Science and Technology》2016,13(5):1229-1234
Heavy metals toxicity is a significant problem for ecological, evolutionary, nutritional and environmental reasons. This study was carried out to evaluate the amount of cadmium, zinc and lead absorption in leaf and root of pine, cypress, plantain and ash in Isfahan, Iran, in 2013. For this purpose, three heavy metals (Cd, Pb and Zn) and three sites (heavy traffic, moderate traffic and control) were chosen based on their effects on human health. The results indicated that the highest and lowest lead and cadmium concentrations belonged to heavy traffic site and control site, respectively. Cd in leaf versus Pb in leaf and Cd in root versus Pb in root had the highest correlation coefficient among the traits indicating positive influence of leaf and root on absorbing Cd and Pb from soil, water and air. In all the studied species, the concentration of Pb was higher than that of Cd and Zn. This was certainty due to the vehicle traffic emitting much more lead than cadmium and zinc. In all the studied species, metal concentration in leaves was higher than in roots, which may be due to high concentration of heavy metals in air than in soil. In this study, Pinus eldarica Medw. tree was found to be the best species to monitor polluted sites in Isfahan city. 相似文献
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Thirty percent of present industrial water consumption of the Golgohar Iron Ore Mine (GIOM) is supplied from a hard rock well (PW-A15) and the rest from 25 wells located in 4 disconnected alluvial aquifers. This well is drilled in the metamorphic complex of Golgohar formation. Attempts have been made to develop extraction of water from other hard rocks existing in the area with no success. Therefore, extensive researches have been carried out to find the pathway, or a provision pathway of water discharged from this well. To study the hydrochemical similarity of this water with other water resources, 122 water samples from an area of 7132 km2 were collected from the existing pumping wells, piezometers, mine exploration bore holes, and three salt pans in the vicinity of the area for hydrochemical analysis. The analyses were performed for concentration of major ions and some minor elements. Furthermore, the spatial distribution of ion concentration was plotted in the GIS to delineate the similarity of the PW-A15 water with other water sources and their hydrochemical neighborhood by analytical hierarchy process (AHP). The AHP was performed in two steps: first, iso-concentration maps of seven major ions, eight minor elements, and TDS were used to produce an AHP map (Map1) using weights for different hydrochemical parameters; and second, a similarity index (SI) map was prepared by performing a suggested clustering approach in SPSS using K-means clustering, which was overlaid on Map1 producing Map2. The result of AHP Map2 was then overlaid on the iso-potential map of the sampled locations in GIS software using a mask operator. Therefore, the zones having the most similarity and higher hydraulic potential than PW-A15 were nominated as the zones which possibly could recharge this well, and the groundwater (GW) pathway was proposed. The result of the study method showed to be successful and will be used as a guide for future exploration drillings. 相似文献
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K. Zare 《Celestial Mechanics and Dynamical Astronomy》1976,14(1):73-83
Regions of possible motions are established for dynamical systems possessing time-independent Hamiltonians or for systems which are reducible to that form by means of integrals of the motion using only extended point transformations. The method is applied to the problem of three bodies in a plane and surfaces of zero velocity are found. The governing parameters are the energy, angular momentum and the masses of the participating bodies. The analytical and geometrical properties of these surfaces provide qualitative results for given constants of the motion. 相似文献
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Navid Hosseini Kamran Goshtasbi Behdeen Oraee-Mirzamani Mehran Gholinejad 《Arabian Journal of Geosciences》2014,7(5):1951-1956
The state of periodic loading and the interval of periodic roof weighting have an important role in geomechanical stability and, hence, in the continuity of longwall mining operations. In this paper, the mechanism of roof caving in longwall mining—together with the effect of engineering and geomechanical properties of surrounding rock masses on the magnitude and timing of periodic loading—is studied. For this purpose, a longwall mine is first modeled using Phase2 software, and then, by simulating the roof caving process, the periodic roof weighting intervals is calculated. Based on the numerical modeling, the first roof weighting interval and the periodic roof weighting interval are calculated as 27.2 and 12.1 m, respectively. Sensitivity analysis is then applied to determine the effect of changes in the mechanical properties of the rock mass, especially in the main roof and immediate roof. The results of the analysis show that as GSI and quality of the immediate roof increases, the periodic roof weighting interval also increases. Hence, the applied algorithm in this research study can effectively be utilized to calculate the periodic roof weighting interval in the longwall mining method. 相似文献
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Mostafa Moradi Dashtpagerdi Seyed Javad Sadatinejad Rafat Zare Bidaki Ehsan Khorsandi 《Journal of the Indian Society of Remote Sensing》2014,42(1):179-186
In this paper, remote sensing and GIS have been used to assess the status of NO2 at the south west of Iran. 221 data about concentration of NO2 was extracted from Ozone Monitoring Instrument. Ordinary kriging and inverse distance weighting interpolation methods was used to interpolate data. Results showed that ordinary kriging method using cross-validation have had less error. North east of the study area has the highest concentration of NO2 (329 molecule/cm2) and the concentration of NO2 decreases from north east to South west of the study area. On the other hand, data trend results showed that the data seems to exhibit a fairly strong trend in the east west direction and a weaker one in the north–south direction. 相似文献
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Natural Hazards - This paper has classified nine attenuation laws derived for subduction interface earthquakes through a comparative study based on the peak ground accelerations (PGAs) recorded in... 相似文献