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21.
R. Rooki F. Doulati Ardejani A. Aryafar A. Bani Asadi 《Environmental Earth Sciences》2011,64(5):1303-1316
Water is one of the basic and fundamental requirements for the survival of human beings. Mining of the sulphide mines usually
produce a significant amount of acid mine drainage (AMD) contributing to huge amounts of chemical components and heavy metals
in the receiving waters. Prediction of the heavy metals in the AMD is important in developing any appropriate remediation
strategy. This paper attempts to predict heavy metals (Cu, Fe, Mn, Zn) from the AMD using backpropagation neural network (BPNN),
general regression neural network (GRNN) and multiple linear regression (MLR), by taking pH, sulphate (SO4) and magnesium (Mg) concentrations in the AMD into account in Shur River, Sarcheshmeh porphyry copper deposit, southeast
Iran. The comparison between the predicted concentrations and the measured data resulted in the correlation coefficients,
R, 0.92, 0.22, 0.92 and 0.92 for Cu, Fe, Mn and Zn ions using BPNN method. Moreover, the R values were 0.89, 0.37, 0.9 and 0.91 for Cu, Fe, Mn, and Zn taking the GRNN method into consideration. However, the correlation
coefficients were low for the results predicted by MLR method (0.83, 0.14, 0.9 and 0.85 for Cu, Fe, Mn and Zn ions, respectively).
The results further indicate that the ANN can be used as a viable method to rapidly and cost-effectively predict heavy metals
in the AMD. The results obtained from this paper can be considered as an easy and cost-effective method to monitor groundwater
and surface water affected by AMD. 相似文献
22.
Minimum, maximum, and mean annual temperatures, relative humidity, and precipitation trends in arid and semi-arid regions of Iran 总被引：2，自引：1，他引：1
One of the most important scientific concerns of the last few decades is climate change, which is the result of a great many factors like global warming. Although a number of studies have been dedicated to understand the phenomenon of climate change, more attention is required to understand the potential effects of global warming on the ecosystems as well as on human life. The present study was designed to survey the trends of minimum, maximum and mean temperatures, relative humidity, and the time series of annual precipitation and 10-year moving average low-pass filter in the 13 synoptic weather stations of Iran’s arid and semi-arid regions during the last 55 years by using τ Kendall test. The analyses indicate a significantly increasing trend for the minimum and mean temperatures while a decreasing trend for the mean relative humidity in the arid and semi-arid regions, especially during the last few years up to the year 2000. Any clear increasing or decreasing trend was not found for the maximum temperature, while the precipitation did not show any increasing/decreasing trend for most of the surveyed stations. Further studies, with long-term programming, are recommended to be carried out to evaluate the climate change and its effects on such regions. 相似文献
23.
We study the late-time cosmological viability of the solutions in the DGP braneworld scenario. We consider a quintessence field trapped on the normal branch of the DGP model and we suppose this scalar field is both minimally and non-minimally coupled to induced gravity on the brane. Since a successful cosmological model should therefore admit for a sequence of epochs: a radiation era, a sufficiently long matter dominated era and a final stable positively accelerated scaling solution, we analyze the cosmological properties of system in its critical points. 相似文献
24.
Mohsen Asadi Nader Shariatmadari Mehran Karimpour-Fard Ali Noorzad 《Geotechnical and Geological Engineering》2017,35(5):2003-2015
The increasing demand of engineering landfills requires that designers propose a framework for landfill design, construction, repair and maintenance. As municipal solid waste (MSW) is a major part of a landfill, the analysis should consider MSW mechanical behavior using a constitutive model. To investigate this, 18 direct shear (DS) and triaxial (TX) tests were conducted on MSW samples with different fiber contents. Different shearing mechanisms lead to understand effects of fibers on stress–strain response. Based on obtained results the hyperbolic model Duncan and Chang (J Soil Mech Found Div 96(5):1629–1653, 1970) has been employed to simulate the TX results indicating the ability of the model to predict stress–strain behavior of MSW. This model could also be employed to the DS test results with some assumptions. The model can capture DS stress–strain response well whereas for TX tests the predictions were just enough. The experimental results and two sets of proposed MSW parameters of hyperbolic model have been compared and discussed. 相似文献
25.
National Persian Gulf Bridge is a communication route between Bandar Abbas port and Qeshm Island located on the southern border of Iran. This causeway has important role for facilitating the transportation system between Qeshm Island and mainland, i.e., Bandar Abbas. Based on geotechnical and geological site investigation records, the bridge is located on the deposits with high seismic possibility and subsequently significant dynamic loading. Therefore, adequate substructure design of this bridge as an offshore project is realized as a major requirement. The geophysical and geotechnical investigations have been done to obtain the subsoil characteristics of the project site. For this purpose, 18 boreholes have been performed to do in situ tests and extract samples for laboratory testings. Data synthesis indicates that in the zones close to Qeshm Island and in the deeper parts of the sea, the strata is made of clay with loose sands and some depths, with silty sands. Hence, instability issues, including the low bearing capacity and the high differential settlement, are significant aspects in analysis and design of substructure for this project. Also, in this paper, the subsoil conditions have been studied from in situ tests such as standard penetration test (SPT) and cone penetration test (CPT) results in order to achieve an appropriate foundation system. Moreover, the necessity of the ground improvement of the site has been investigated to propose an efficient technique for safe and secure construction. Based on the analysis and methods screened, the vibro-replacement method is considered as a suitable and efficient ground improvement method for this project. 相似文献
26.
N. Shariatmadari M. Asadi M. Karimpour-Fard 《International Journal of Environmental Science and Technology》2017,14(10):2239-2248
This paper embraces the results of a study on the mechanical behavior of municipal solid waste, MSW, and the effect of shearing mechanism on its mechanical response. Totally, 9 drained direct shear tests and 9 drained triaxial tests have been performed on fresh MSW samples with fiber contents of 0, 6 and 12%. Each apparatus represents a different shearing mechanism. The composition and compaction condition for MSW samples in each fiber content, employed in both shearing test devices, were the same. In triaxial tests, since the shear plane was cutting through the fibers, with increase in the fiber content, an increasing trend of strength was observed; on the contrary, this trend was decreasing in direct shear tests because fiber alignment was parallel to the shear plane. Test results show that the effect of fibers in the triaxial tests depends on the level of imposed axial strain on the samples as well as the confining stress. Based on the findings of this paper, hardening behavior of MSW is attributed to reinforcement action of fibers and particle compressibility. 相似文献
27.
Groundwater vulnerability assessment of urban areas is a challenging task in the fast trend of urbanization around the globe. This study introduces a new approach for modifying well-known parameters of common vulnerability indexes to adjust them for urban areas. The approach is independent of a specific weighting system. The aquifer of Mashhad city, contaminated by domestic wastewater, is selected as a case in this study. In order to evaluate the aquifer vulnerability due to anthropogenic activities, at first, parameters of depth to groundwater, recharge, land use, and soil are modified based on their basic concepts and their influences on contamination attenuation. Then, the modified parameters are used simultaneously in several index methods to investigate the capability of the modified parameters to increase correlation coefficient of all employed index methods with the measured nitrate concentration. Accuracy of the modified methods is evaluated by Spearman nonparametric correlation. It is shown that considering the wastewater discharge into recharge parameter leads to an increase of 20% in correlation coefficient. Also, level difference technique shows that more than 70% of the vulnerable areas are predicted correctly in all utilized methods. The accurate prediction in all employed methods indicates that these modifications are independent of the type of index method. Moreover, sensitivity analysis reveals that the recharge and the land use are both the most significant parameters for evaluating the vulnerability. 相似文献
28.
Fawzi Asadi Dr. 《GeoJournal》1990,21(4):375-383
A key objective of the Israeli occupation of the West Bank and Gaza Strip in Palestine has been to render the economy of these regions dependent on the Israeli economy and thus hamper their economic development. Large areas of land have been confiscated or expropriated by the Israeli authorities to establish Jewish settlements. Other severe measures imposed include control of irrigation water and obstacles for the Arab agricultural and industrial sector in the Occupied Territories aimed at preventing Arab competition with Israeli products.Palestinian agriculturalists have met this challenge and have worked to achieve higher production levels in agriculture. Nonetheless, economic development there was blocked, and many agriculturalists sought employment inside Israel. The Intifada since December 1987 has aimed at encouraging Arab economic independence and intensification of efforts to meet national requirements of greater self-sufficiency in subsistence crops and stimulation of agriculture-related industries. The Intifada is thus functioning as a stimulus to development and economic viability. 相似文献
29.
In this study to identify the flow pattern and local scour mechanism around pile groups, the flow field was simulated using FLOW-3D software. A pair of pile on a flat-bed channel with side by side and tandem arrangements was investigated. To establish Navier–Stokes equations, the RNGk-ε turbulence model was used and the results were verified using experimental data. In case of FLOW-3D capability, it was found that the software was able to properly simulate the expected interaction between the pile groups. The results of flow field simulation showed that Reynolds number and the pile spacing are the most influential variables in forming vortices. The flow around tandem pile and the downward flow around wake vortices were more intense and complicate in comparison with side by side arrangements and single pile. 相似文献
30.
Petrography, mineralogy and geochemistry of the Zarshuran Carlin-like gold deposit, northwest Iran 总被引：1，自引：0，他引：1
Gold mineralisation at Zarshuran, northwestern Iran, is hosted by Precambrian carbonate and black shale formations which
have been intruded by a weakly mineralised granitoid. Granitoid intrusion fractured the sedimentary rocks, thereby improving
conditions for hydrothermal alteration and mineralisation. Silicification is the principal hydrothermal alteration along with
decalcification and argillisation. Three hydrothermal sulphide mineral assemblages have been identified: an early assemblage
of pyrrhotite, pyrite and chalcopyrite; then widespread base metal sulphides, lead-sulphosalts and zoned euhedral arsenical
pyrite; and finally late network arsenical pyrite, massive and colloform arsenical pyrite, colloform sphalerite, coloradoite,
and arsenic–antimony–mercury–thallium-bearing sulphides including orpiment, realgar, stibnite, getchellite, cinnabar, lorandite
and a Tl-mineral, probably christite. Most of the gold at Zarshuran is detectable only by quantitative electron microprobe
and bulk chemical analyses. Gold occurs mainly in arsenical pyrite and colloform sphalerite as solid solution or as nanometre-sized
native gold. Metallic gold is found rarely in hydrothermal quartz and orpiment. Pure microcrystalline orpiment, carbon-rich
shale, silicified shale with visible pyrite grains and arsenic minerals contain the highest concentrations of gold. In many
ways Zarshuran appears to be similar to the classic Carlin-type sediment-hosted disseminated gold deposits. However, relatively
high concentrations of tellurium at Zarshuran, evidenced by the occurrence of coloradoite (HgTe), imply a greater magmatic
contribution in the mineralising hydrothermal solutions than is typical of Carlin-type gold deposits.
Received: 13 May 1999 / Accepted: 2 February 2000 相似文献