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In order to investigate the development of forest soils formed on loess, six representative modern soil pedons were selected along a precipitation gradient extending from eastern Golestan(mean annual precipitation, MAP = 500 mm)to eastern Mazandaran Provinces(MAP = 800 mm).Physiochemical, micromorphological and magnetic properties, as well as clay mineralogy of soils were studied using standard methods. Soils are mainly classified as Alfisols and Mollisols. Downward decalcification and the subsequent clay illuviation were the main criteria of soil development in all study areas. Pedogenic magnetic susceptibility of pedons studied varied systematically across the precipitation gradient in Northern Iran, increasing from 14.66 ×10~(-8) m~3 kg~(-1) at the eastern part to 83.75 × 10~(-8) m~3 kg~(-1) at the western margin of this transect. The frequencydependent magnetic susceptibility showed an increasing trend with rainfall as well. The micromorphological study of soils indicated that there is a positive relationship between climate gradient (increasing rainfall) and the micromorphological index of soil development(MISECA). The area and thickness of clay coatings showed an increasing trend with rainfall. Grain size analysis indicates that pedogenic processes are responsible for changing original grain size distribution of loess in our soils.The correlation achieved among modern soil properties and precipitation could be applied to the buried paleosols in the whole study area to refer degree of paleosol development and to reconstruct the paleoclimate. 相似文献
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Mohammad Rezaei Masoud Monjezi Saeed Ghorbani Moghaddam Farhad Farzaneh 《Arabian Journal of Geosciences》2011,5(5):1031-1037
Burden prediction is a vital task in the production blasting. Both the excessive and insufficient burden can significantly affect the result of blasting operation. The burden which is determined by empirical models is often inaccurate and needs to be adjusted experimentally. In this paper, an attempt was made to develop an artificial neural network (ANN) in order to predict burden in the blasting operation of the Mouteh gold mine, using considering geomechanical properties of rocks as input parameters. As such here, network inputs consist of blastability index (BI), rock quality designation (RQD), unconfined compressive strength (UCS), density, and cohesive strength. To make a database (including 95 datasets), rock samples are used from Iran’s Mouteh goldmine. Trying various types of the networks, a neural network, with architecture 5-15-10-1, was found to be optimum. Superiority of ANN over regression model is proved by calculating. To compare the performance of the ANN modeling with that of multivariable regression analysis (MVRA), mean absolute error (E a), mean relative error (E r), and determination coefficient (R 2) between predicted and real values were calculated for both the models. It was observed that the ANN prediction capability is better than that of MVRA. The absolute and relative errors for the ANN model were calculated 0.05 m and 3.85%, respectively, whereas for the regression analysis, these errors were computed 0.11 m and 5.63%, respectively. Moreover, determination coefficient of the ANN model and MVRA were determined 0.987 and 0.924, respectively. Further, a sensitivity analysis shows that while BI and RQD were recognized as the most sensitive and effective parameters, cohesive strength is considered as the least sensitive input parameters on the ANN model output effective on the proposed (burden). 相似文献
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Evaluating the Sensitivity of Image Fusion Quality Metrics to Image Degradation in Satellite Imagery
Farhad Samadzadegan Farzaneh DadrasJavan 《Journal of the Indian Society of Remote Sensing》2011,39(4):431-441
Referring to the high potential of topographic satellite in collecting high resolution panchromatic imagery and high spectral,
multi spectral imagery, the purpose of image fusion is to produce a new image data with high spatial and spectral characteristics.
It is necessary to evaluate the quality of fused image by some quality metrics before using this product in various applications.
Up to now, several metrics have been proposed for image quality assessment; which are also applicable for quality evaluation
of fused images. However, it seems more investigations are needed to inspect the potentials of proposed Image Fusion Quality
Metrics (IFQMs) to registration accuracy, especially in high resolution satellite imagery. This paper focuses on such studies
and, using different image fusion quality metrics, experiments are conducted to evaluate the sensitivity of such metrics to
a set of high resolution satellite imagery covering urban areas. The obtained results clearly reveal that these metrics sometimes
do not behave robust in the whole area and also their obtained results are inconsistence in different patch areas in comparison
with the whole image. These limitations are in minimum situation for an image quality metric such as SAM and are completely
tangible for image quality metrics such as ERGAS in case of multi modal and DIV and CC from mono modal category. 相似文献
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Identification and characterization of aeolian deposits in arid environments provide information on mechanisms of loess and sand accumulation. The objectives of this study were to (i) identify the distribution of aeolian deposits, (ii) discriminate loess and sand deposits using granulometric data, and (iii) describe the aeolian deposition in Sarakhs area, northeastern Iran. Particle size distributions of 26 surface samples were determined using a laser grain-size analyzer. Fine sand, very fine sand, and very coarse silt were dominant fractions in studied sediments, and the sum of these fractions ranged from 46.9% in loess deposits to 93.8% in sand dunes. The mean grain size (M z ) of sand dunes ranged from 3.31 to 3.54 ?, which gradually changed to 4.09 to 5.50 ? in loess deposits. Sorting, skewness, and kurtosis ranged from 0.84 to 1.94 ?, 0.18 to 0.49, and 0.76 to 2.38, respectively. Aeolian deposits in the area resulted in the incorporation of Hariroud River system and Kopeh Dagh Mountains for aeolian particle production and accumulation. Alluvial comminution in Hariroud River is suggested the main mechanism of sand and silt production and flood plain environment the main reservoir of these particles. The mountains of Kopeh Dagh act as a barrier and play a key role for sand and loess accumulation. 相似文献
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Numerically based proposals for the stiffness and strength of masonry infills with openings in reinforced concrete frames 
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下载免费PDF全文 Aimed at investigating the effect of openings on the in‐plane behaviour of masonry infills in reinforced concrete frames, a parametric study is presented based on model calibration via experimental tests. Two types of openings are investigated: central window openings and different combinations of door and window openings based on the typologies of southern European countries. First, a finite element model of the structure is made using the DIANA software program. Then, after calibration with experimental results, a parametric analysis is carried out to investigate the effect of the presence and location of the different types of openings on the in‐plane behaviour of the infilled frame. Finally, different equations for predicting the initial stiffness and lateral strength of infilled frames with any types of openings were obtained. An α factor related to the geometry of the piers between openings is proposed to take into account the location of the openings in the developed equations. Subsequently, the masonry infill panel is replaced by a diagonal strut. An empirical equation is also proposed for the width of an equivalent strut to replace a masonry infill panel with openings in such a way that they possess the same initial stiffness. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
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In order to study the effects of different land vegetative covers on soil quality attributes, a loess hill slope was selected in eastern Golestan Province, Ghapan watershed, Iran. Four profiles in four land uses, including Quercus natural forest; Pinus artificial forest; Cupressus artificial forest and a cultivated land, were studied. Results showed that MWD was significantly different in the studied land uses, and it varied between 1.6 mm in Quercus natural forest and o.31 mm in cultivated land use. The lowest CEC, microbial respiration rate and organic carbon were 28.4 cmol·kg^1, 177 μgCO2·g^-1·day^-1 and 1.32 % found in cultivated land use, respectively. The organic matter was considerably higher content in the forest areas than that of cultivated land use. The studies on soil profile development revealed that the natural forest soils were highly developed. The soils of the Quercus natural forest were classified as Calcic Haploxeralfs with a well developed argillie horizon unlike the cultivated soils which showed the minimum development and classified as Typic Xerorthents. The soils of the artificial forests had both mollic epipedons and were classified as Typic Calcixerolls with moderate profile development. Micromorphological studies revealed that argillic horizons had speckled and partly crystallitic b-fabric in the natural forest indicating the high landscape stability. In contrast, the crystallitic b-fabric of other land uses shows the absence of enough leaching of carbonate and the subsequent migration of clay particles indicating the unstable conditions and high soil erosion. Intense erosion of the surface horizons of cultivated land use has resulted in the outcropping of the subsurface carbonate rich horizons preventing soil development. 相似文献
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The Paleozoic Ozbak-Kuh carbonate-hosted Pb-Zn deposit of East Central Iran: Isotope (C,O, S,Pb) geochemistry and ore genesis 总被引：1，自引：0，他引：1
Farhad Ehya 《Mineralogy and Petrology》2014,108(1):123-136
Lead and zinc mineralization occurs in dolostones of the Middle Devonian Sibzar Formation at Ozbak-Kuh, which is located 150 km north of Tabas city in East Central Iran. The ore is composed of galena, sphalerite and calcite, with subordinate dolomite and bitumen. Wall-rock alterations include carbonate recrystallization and dolomitization. Microscopic studies reveal that the host rock is replaced by galena and sphalerite. The Pb–Zn mineralization is epigenetic and stratabound. The δ13C values of hydrothermal calcite samples fall in the narrow range between ?0.3‰ and 0.8‰. The δ18O values in calcite display a wider range, between ?14.5‰ and ?11.9‰. The δ13C and δ18O values overlap with the oxygen and carbon isotopic compositions of Paleozoic seawater, indicating the possible important participation of Paleozoic seawater in the ore-forming fluid. The δ18O signature corresponds to a spread in temperature of about 70 °C in the ore-bearing fluid. The δ13C values indicate that the organic materials within the host rocks did not contribute significantly in the hydrothermal fluid. The δ34S values of galena and sphalerite samples occupy the ranges of 12.2‰–16.0‰ and 12.1–16.8‰, respectively. These values reveal that the seawater sulfate is the most probable source of sulfur. The reduced sulfur was most likely supplied through thermochemical sulfate reduction. The sulfur isotope ratios of co-precipitated sphalerite–galena pairs suggest that deposition of the sulfide minerals took place under chemical disequilibrium conditions. The 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb ratios of the galena samples represent average values of 18.08, 15.66, and 38.50, respectively. These ratios indicate that galena Pb likely originated from an orogenic source in which supracrustal rocks with high 238U/204Pb and 232Th/204Pb ratios are dominant. The average lead isotope model age portrays Cambrian age. This model age is not coeval with the host rocks, which are of middle Devonian age. It is probable that the pre-Middle Devonian model age shows the derivation of Pb from older sources either from host rocks of Cambrian age or from deposits previously formed in these rock units. The Pb isotopic composition of galena accords with the occurrence of an orogenic activity from Late Neoproterozoic to Lower Cambrian in Central Iran. The proposed genetic model considers the fact that mineralization formed in fractured and brecciated host rocks along shear zones and faults from metal-bearing connate waters that were discharged due to deformational dewatering of sediments. 相似文献
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Farhad?GhiaeiEmail author Murat?Kankal Tugce?Anilan Omer?Yuksek 《Theoretical and Applied Climatology》2018,131(1-2):245-257
The analysis of rainfall frequency is an important step in hydrology and water resources engineering. However, a lack of measuring stations, short duration of statistical periods, and unreliable outliers are among the most important problems when designing hydrology projects. In this study, regional rainfall analysis based on L-moments was used to overcome these problems in the Eastern Black Sea Basin (EBSB) of Turkey. The L-moments technique was applied at all stages of the regional analysis, including determining homogeneous regions, in addition to fitting and estimating parameters from appropriate distribution functions in each homogeneous region. We studied annual maximum rainfall height values of various durations (5 min to 24 h) from seven rain gauge stations located in the EBSB in Turkey, which have gauging periods of 39 to 70 years. Homogeneity of the region was evaluated by using L-moments. The goodness-of-fit criterion for each distribution was defined as the ZDIST statistics, depending on various distributions, including generalized logistic (GLO), generalized extreme value (GEV), generalized normal (GNO), Pearson type 3 (PE3), and generalized Pareto (GPA). GLO and GEV determined the best distributions for short (5 to 30 min) and long (1 to 24 h) period data, respectively. Based on the distribution functions, the governing equations were extracted for calculation of intensities of 2, 5, 25, 50, 100, 250, and 500 years return periods (T). Subsequently, the T values for different rainfall intensities were estimated using data quantifying maximum amount of rainfall at different times. Using these T values, duration, altitude, latitude, and longitude values were used as independent variables in a regression model of the data. The determination coefficient (R 2) value indicated that the model yields suitable results for the regional relationship of intensity–duration–frequency (IDF), which is necessary for the design of hydraulic structures in small and medium sized catchments. 相似文献
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Recently it has been shown that for finite and small values of the electron Debye length, the ion polytropic coefficient is approached to some constant value in the plasma sheath region by decreasing the plasma density. In this paper, using a plasma multi fluid model, the effect of ion polytropic coefficient γ i on the plasma sheath structure have been examined. The numerical calculations of the basic equation of the model show that the polytropic coefficient strongly affects on the plasma sheath characteristics. The results show that by transition from an isothermal flow (γ i =1) to an adiabatic flow (γ i =3), the net current to the wall and the electric potential distribution increase and the sheath width decreases in a thermal plasma sheath. 相似文献