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31.
Zinc extraction from Iranian low-grade complex zinc–lead ore by two native microorganisms: Acidithiobacillus ferrooxidans and Sulfobacillus 总被引：2，自引：0，他引：2
S.M. Mousavi S. Yaghmaei M. Vossoughi A. Jafari R. Roostaazad 《International Journal of Mineral Processing》2006,80(2-4):238-243
A mesophilic iron oxidizing bacterium, Acidithiobacillus ferrooxidans, has been isolated (33 °C) from a typical, chalcopyrite concentrate of the Sarcheshmeh copper mine in the region of Kerman located in the south of Iran. In addition, a thermophilic iron oxidizing bacterium, Sulfobacillus, has been isolated (60 °C) from the sphalerite concentrate of Kooshk lead and zinc mine near the city of Yazd in the center point of Iran. Variation of pH, ferrous and ferric concentration on time and effects of some factors such as temperature, cell growth, initial ferrous concentration and pH on bioleaching of low-grade complex zinc–lead ore were investigated. The results obtained from bioleaching experiments indicate that the efficiency of zinc extraction is dependent on all of the mentioned variables; especially the temperature and initial Fe(II) concentration have more effect than other factors for these microorganisms. In addition, results show that the maximum zinc recovery was achieved using a thermophilic culture. Zinc dissolution reached 58% with Sulfobacillus while it was 51% with A. ferrooxidans at pH = 1.5, initial Fe(II) concentration = 7 and 9 g/L for A. ferrooxidans and Sulfobacillus, respectively, after 30 days. 相似文献
32.
M. K. Jafari F. Pellet M. Boulon K. Amini Hosseini 《Rock Mechanics and Rock Engineering》2004,37(1):3-23
Summary Evaluation of the effects of small repetitive earthquakes on the strength parameters of rock joints in active seismic zones is of interest of the designers of underground constructions. In order to evaluate these effects, it is necessary to study the behaviour of rock joints under dynamic and cyclic loadings. This paper presents the results of a systematic study on the behaviour of artificial rock joints subjected to cyclic shearing. More than 30 identical replicas have been tested using triaxial compression devices under different conditions of monotonic and cyclic loading. At the first stage a few samples have been tested in monotonic loading modes under various confining pressures and rate of displacement. In the second series of tests, small cyclic loads were applied on the samples for increasing number of cycles, frequency levels and stress amplitudes. These were then followed by monotonic loading again. The variations of maximum and residual shear strengths for each test have been studied. The results show increase of shear strength as a result of the increase in confining pressure and they display decrease of shear strength due to the increase of rate of loading, number of cycles, frequency levels and stress amplitudes. 相似文献
33.
Post-Cyclic Undrained Behavior of Compacted Composite Clay Subjected to Various Cyclic Loading Paths
H. R. Tavakoli A. Shafiee M. K. Jafari 《Geotechnical and Geological Engineering》2011,29(6):1085-1097
Using a sequential procedure of undrained cyclic and post cyclic tests, the strength and stiffness degradation characteristics
of compacted composite clays are studied immediately after various cyclic loading paths by triaxial and hollow cylinder tests.
The effects of cyclic loading paths, sand contents, cyclic loading amplitude and confining pressure on the post-cyclic mechanical
behavior of the composite clays are evaluated. The results point out different peculiarities which can be of interest in assessing
the mechanical behavior of the composite clays under post seismic shaking. The results show that effect of cyclic loading
on post cyclic pore water pressure build-up is significant when pore water pressure build-up is considerably lower than the
associated value in monotonic loading. The effect of sand content and cyclic loading path on degradation of stiffness is more
remarkable than shear strength. Test results also reveal that the effect of sand content on the post cyclic pore water pressure
build-up is minor. However, when the aggregate content increases the shear strength increases. 相似文献
34.
Shirin Mohammadkhan Hasan Ahmadi Mohammad Jafari 《Arabian Journal of Geosciences》2011,4(1-2):331-338
Soil erosion is the dominating factor of damaging roads in Iran. Roads are a critical component of civilization. Developing and maintaining the economic activity that is vital for the quality of modern life would be difficult without roads. Accelerated erosion and increased sediment yields resulting from changes in land use are critical environmental problems, and one of the important changes is road construction. Construction and condition of roadways are associated with direct and indirect impacts on soil erosion. This paper presents the relationship between soil erosion and some characteristics such as distance to roadway, slope, and parent material in Latian Watershed, Tehran Province, Iran. Soil erosion map was interpreted using aerial photos and GIS technology. Buffer zones, subdivided into 12 strips, each 0.2 km wide, which were located alongside roadway. The distribution patterns of various types of erosion were also identified by GIS by overlaying road buffer strips and soil erosion map. The results show that soil erosion landform such as land slide, badland, bank erosion, channel erosion, etc. found in buffer zones along both sides of roads. 相似文献
35.
E. Jafari S. Soleymani B. Mozafari T. Amraee 《International Journal of Environmental Science and Technology》2018,15(10):2169-2182
In profit-based unit commitment, the objective of programming is to maximize profit and optimize generation. Practically, the gross profit depends not only on the revenue but also on the total expenditures. In this article, an efficient algorithm is suggested to assess the effect of uncertainties in determining 24-hour optimal strategy of a microgrid (MG) containing wind farms, photovoltaic, fuel cell, combined heat and power units, boiler, and energy storage devices (ESDs). The optimization problem is presented to determine the optimal points for the energy resources generation and to maximize the expected profit considering demand response (DR) programs and uncertainties. The uncertainties include wind speed, photovoltaic power generation (PVPG), market price, power, and thermal load demand. For modeling uncertainties, an effort has been made to predict uncertainties through the hybrid method of wavelet transform (WT)-artificial neural network (ANN)-imperialist competitive algorithm (ICA). In this study, three cases are assessed to confirm the performance of the proposed method. In the first case study, programing MG is isolated from the grid. In the second case study, which is grid-connected mode the WT-ANN-ICA and WT-ANN uncertainties predictions methods are compered. In the third case, which is grid-connected mode the effect of DR programs on the expected profit of energy resources is assessed. 相似文献
36.
Industrial sites are key factors in urban and regional land use planning. Therefore, determining the location of industrial areas is a critical and complex process for development and success. Industrial site selection aims in identifying the most suitable sites for industry creation, considering a set of influential criteria. Therefore, site selection generally and industrial site selection specifically can be categorised as a multi-criteria decision-making (MCDM) problem that requires detailed evaluation of various dimensions. This study developed a set of clusters containing 10 selection criteria for industrial site selection in Isfahan metropolitan area, Iran. The relationships between the criteria and clusters were modelled and analysed using analytical hierarchy process (AHP) and analytical network process (ANP). AHP and ANP agree in finding distance to water bodies and distance to other industries as the most and least important selection criteria. Four patches have been identified as suitable alternatives for industrial construction. While AHP found Borkhar Patch 1 as the most appropriate alternative, ANP demonstrated the superiority of Ardestan Patch over others. Conducting a sensitivity analysis for the models confirmed both models robustness in industrial site selection decisions. 相似文献
37.
Yamin Pouryousef Jafar Seyfabadi Hamid Rezai Alireza Mahvari Mohammad Ali Jafari 《海洋学报(英文版)》2022,41(12):48-57
The abundance and health of scleractinian coral communities of Hormuz Island were investigated. For this purpose, we employed 20 m line intercept transects—12 in the intertidal zone and 15 subtidally to evaluate coral cover and community composition. The estimated dead coral coverage was 6.21%±0.81%, while live coral coverage was 16.93%±1.81%, considered as very poor. Totally, 12 genera were recorded, of which Porites with 11.9%±1.4% live cover was the dominant, while Goniopora had the least cover (0.07%±0.08%). Based on Mann-Whitney U-test, live coral coverage, dead coral coverage, algal coverage, cover of other benthic organisms and abiotic components showed significant univariate differences between zones (p<0.05). The Spearman correlation test between the abundance of biotic and abiotic components indicated significant negative correlation of live coral and sand with zoantharian and significant positive correlation of algae and other benthic organisms with rubble. The reef health indices used for the corals indicated that, in general, the environmental conditions were not suitable, which could be attributed to both natural and anthropogenic factors, the most important of which was zoantharian’ overgrowth on the scleractinian corals in this region. 相似文献
38.
S. Amir Reza Beyabanaki Ahmad Jafari S. Omid Reza Biabanaki M. Ronald Yeung 《Computers and Geotechnics》2009
This paper presents a new numerical model that can add a finite element mesh into each block of the three-dimensional discontinuous deformation analysis (3-D DDA), originally developed by Gen-hua Shi. The main objectives of this research are to enhance DDA block’s deformability. Formulations of stiffness and force matrices in 3-D DDA with conventional Trilinear (8-node) and Serendipity (20-node) hexahedral isoparametric finite elements meshed block system due to elastic stress, initial stress, point load, body force, displacement constraints, inertia force, normal and shear contact forces are derived in detail for program coding. The program code for the Trilinear and Serendipity hexahedron elements have been developed, and it has been applied to some examples to show the advantages achieved when finite element is associated with 3-D DDA to handle problems under large displacements and deformations. Results calculated for the same models by use of the original 3-D DDA are far from the theoretical solutions while the results of new numerical model are quite good in agreement with theoretical solutions; however, for the Trilinear elements, more number of elements are needed. 相似文献
39.
Rasool Zamani-Ahmadmahmoodi Ali Jafari Hojatollah Alibeygi-beni 《Environmental Earth Sciences》2017,76(11):398
This study reported the first comprehensive research on identification of metal concentrations (Fe, Mg, Mn, Pb, Cd, Cr) in order to provide baseline data for future studies, identify possible sources, determine degree of pollution, and identify potential ecological risks of metals in surface sediments from Iran’s Choghakhor Wetland. The order of metal concentration was as follows: Fe > Mg > Mn > Pb > Cd > Cr, with mean concentrations of 6140.35, 1647.32, 289.03, 1.10, and 0.45 µg/g of dry weight, respectively. These results reveal that Choghakhor Wetland is not heavily polluted compared to other regions. The results of enrichment factor (EF) and geoaccumulation index (I geo) showed that Fe, Pb, Mg, Cr, and Mn presented low levels of contamination and probably originated from natural sources. On the other hand, the results of EF and I geo indices suggested that Cd concentrations in sediments of Choghakhor Wetland originated from anthropogenic sources. Based on the results of three sets of sediment quality guidelines, only Cd concentration in sediments of Choghakhor Wetland is a threat for aquatic organisms of Choghakhor Wetland. The results of multivariate analysis such as principal component analysis and cluster analysis showed that Fe–Mn, Cr–Mg, and Pb groups originated from natural sources, while Cd concentrations in sediments of Choghakhor Wetland originated from both natural and anthropogenic sources (mainly chemical fertilizers). To our knowledge, this is the first study about metal concentrations in sediments of Choghakhor Wetland, and because of low levels of these metals, these concentrations can be considered background levels for future investigation. 相似文献
40.
This study challenges the use of three nature‐inspired algorithms as learning frameworks of the adaptive‐neuro‐fuzzy inference system (ANFIS) machine learning model for short‐term modeling of dissolved oxygen (DO) concentrations. Particle swarm optimization (PSO), butterfly optimization algorithm (BOA), and biogeography‐based optimization (BBO) are employed for developing predictive ANFIS models using seasonal 15 min data collected from the Rock Creek River in Washington, DC. Four independent variables are used as model inputs including water temperature (T), river discharge (Q), specific conductance (SC), and pH. The Mallow's Cp and R2 parameters are used for choosing the best input parameters for the models. The models are assessed by several statistics such as the coefficient of determination (R2), root‐mean‐square error (RMSE), Nash–Sutcliffe efficiency, mean absolute error, and the percent bias. The results indicate that the performance of all‐nature‐inspired algorithms is close to each other. However, based on the calculated RMSE, they enhance the accuracy of standard ANFIS in the spring, summer, fall, and winter around 13.79%, 15.94%, 6.25%, and 12.74%, respectively. Overall, the ANFIS‐PSO and ANFIS‐BOA provide slightly better results than the other ANFIS models. 相似文献