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排序方式: 共有260条查询结果,搜索用时 15 毫秒
1.
Various bituminous artifacts were excavated from the Tall-e Abu Chizan, a late prehistoric (Middle Susiana to Middle Uruk) settlement on the middle of the Curvy plain, between the Karun River and the Ram Hormoz Plain. All samples dated from the Vth millennium BC and cover three periods: 5000–4700 BC (Late Middle Susiana), 4700–4200 BC (Late Susiana 1) and 4200–3900 BC (Late Susiana 2). The bitumens were studied using the techniques of petroleum geochemistry and were compared both to the unaltered crude oils produced from the main oil fields in the area and to the famous Mamatain oil seeps. All samples are very rich in bitumen (average 46 wt%) which has been biodegraded and oxidized. Despite these alteration phenomena, δ13C of asphaltenes occur within a narrow range of less than 1‰ PDB. Biodegradation affected the steranes, terpanes, dibenzothiophenes and mono- and triaromatic steroids. Molecular characteristics of terpanes, especially the occurrence of 18α (H)-oleanane, suggest that the bitumen from Tall-e Abu Chizan is a mixture generated from Cretaceous Kazdhumi and Eocene Pabdeh petroleum source rocks. In that respect, bitumens from Tall-e Abu Chizan belong to the same oil family as oil from the Naft Safid field, which is in the vicinity of the archaeological site. In fact, the bitumen at Tall-e Abu Chizan likely originated from oil seepages at Naft Safid. These oil seeps have not yet been sampled or analysed. 相似文献
2.
对于贝加尔湖-石卷地学断面(BAMSIP)的西段俄罗斯贝加尔湖-中国满洲里断面城内的地质构造背景、地震剖面波类型和基本特征等研究发现:(1)断面域中贝加尔裂谷带地震波速度结构存在异常地幔带;结晶地壳物质成分基性程度较高;基底顶面和Moho界面未观察到明显的镜象关系;(2)西伯利亚南部的复杂相故基底由古生代和前寒武纪岩层所组构;区域构造由古褶皱系、中生代沉积盆地、裂谷带构成。 相似文献
3.
S. Abarghoei A. Hedayati R. Ghorbani H. K. Miandareh T. Bagheri 《International Journal of Environmental Science and Technology》2016,13(7):1753-1760
This study aimed to compare histopathological effect of waterborne silver nanoparticles and silver salt (AgNO3) on the gills and liver of Carassius auratus. Therefore, one hundred and five live specimens of goldfish were obtained and treated in five aquariums with 0, 0.01, 0.025, 0.05, and 0.1 ppm of AgNO3 and 0, 0.1, 0.5, 1, and 5 ppm of Ag nanoparticles (mean particle size of 5 nm). Fish were sampled after 14 days of exposure. Results showed that the kinds of pathologies observed with Ag NPs were broadly of the same type as AgNO3 including hyperplasia, edema and lifting of the gill epithelium, and lamellar fusion of the gills, and hemosiderosis, hemorrhage, hydropic swelling, and pyknotic nuclei of the liver. Overall, the data showed that although Ag nanoparticles and AgNO3 pathology were similar, but Ag nanoparticles caused less injury than AgNO3 in the gills and liver of goldfish. Therefore, it is more proper to use nanoform of Ag in industrials. 相似文献
4.
Sheida Jalili Sajad Ahmad Hamidi Saeed Morid Reza Namdar Ghanbari 《Arabian Journal of Geosciences》2016,9(14):644
Recent decline in Lake Urmia water level makes it crucial to consider this issue more seriously. For this purpose, comparison of water level in Lake Urmia with Lake Van in Turkey, which is in relatively similar geographic and climate conditions, can be an effective approach. To follow this objective, trend analysis, regime shift, and coherency analyses are implemented. The results showed negative trend in Lake Urmia water level for the past 20 years, while in Lake Van, the trend is positive. Moreover, correlation of the lake level variations versus the basin rainfall during three common periods, identified by the regime shifts analysis, illustrated a decreasing trend in the correlation. These changes can be attributed to non-climatic factors such as different allocation disciplines in two lake’s catchments. Finally, the coherency analysis showed significant annual and inter-annual frequencies common between the two lake levels. Herein, the short-term period relations are associated with lags, while in long term, they act simultaneously. 相似文献
5.
Rahim Barzegar Asghar Asghari Moghaddam Amir Hossein Nazemi Jan Adamowski 《Environmental Earth Sciences》2018,77(16):597
Rapid population growth, industrialization, and agricultural expansion in the Khoy area (northwestern Iran) have led to its dependence on groundwater and degradation of groundwater quality. This study attempts to decipher the major processes and factors that degrade the groundwater quality of the Khoy plain. For this purpose, 54 groundwater samples from unconfined and confined aquifers of the plain were collected in July 2017 and analyzed for major cations and anions (Na, K, Ca, Mg, HCO3, SO4, and Cl), minor ions (NO3 and F), and Al. Magnesium and bicarbonate were identified as the dominant cation and anion, respectively. Several ionic ratios and geochemical modeling using PHREEQC indicated that the most important hydrogeochemical processes to affect groundwater quality in the plain were weathering and dissolution of evaporitic and silicate minerals, mixing, and ion exchange. There were smaller effects from evaporation and anthropogenic factors (e.g., industries). Results showed that the high salinity of the groundwater in the northeast area of the plain was due to the high solubility of the evaporitic minerals, e.g., halite and gypsum. Reverse ion exchange and the contribution of mineral dissolution were more significant than ion exchange in the northeastern part of the plain. Elevated salinity of the groundwater in the southeast was attributed mostly to reverse ion exchange and somewhat to evaporation. 相似文献
6.
Behnam Ghorbani Ehsan Sadrossadat Jafar Bolouri Bazaz Parisa Rahimzadeh Oskooei 《Geotechnical and Geological Engineering》2018,36(4):2057-2076
This study explores the potential of adaptive neuro-fuzzy inference systems (ANFIS) for prediction of the ultimate axial load bearing capacity of piles (Pu) using cone penetration test (CPT) data. In this regard, a reliable previously published database composed of 108 datasets was selected to develop ANFIS models. The collected database contains information regarding pile geometry, material, installation, full-scale static pile load test and CPT results for each sample. Reviewing the literature, several common and uncommon variables have been considered for direct or indirect estimation of Pu based on static pile load test, cone penetration test data or other in situ or laboratory testing methods. In present study, the pile shaft and tip area, the average cone tip resistance along the embedded length of the pile, the average cone tip resistance over influence zone and the average sleeve friction along the embedded length of the pile which are obtained from CPT data are considered as independent input variables where the output variable is Pu for the ANFIS model development. Besides, a notable criticism about ANFIS as a prediction tool is that it does not provide practical prediction equations. To tackle this issue, the obtained optimal ANFIS model is represented as a tractable equation which can be used via spread sheet software or hand calculations to provide precise predictions of Pu with the calculated correlation coefficient of 0.96 between predicted and experimental values for all of the data in this study. Considering several criteria, it is represented that the proposed model is able to estimate the output with a high degree of accuracy as compared to those results obtained by some direct CPT-based methods in the literature. Furthermore, in order to assess the capability of the proposed model from geotechnical engineering viewpoints, sensitivity and parametric analyses are done. 相似文献
7.
Sohrabian Babak Hosseinzadeh Gharehgheshlagh Hojjat Soltani-Mohammadi Saeed Abdollahi Sharif Jafar 《Natural Resources Research》2020,29(2):983-1005
Natural Resources Research - Tailings from porphyry copper mines contain environmentally harmful amounts of elements such as copper, molybdenum, lead and cobalt. Geostatistical simulation of... 相似文献
8.
With respect to the different hydrological responses of catchments, even the adjacent ones, in mountainous regions, there are a great number of motivations for classifying them into homogeneous clusters. These motivations include prediction in ungauged basins (PUB), model parameterization, understanding the potential impact of environmental changes, transferring information from gauged catchments to the ungauged ones. The present study investigated the similarity of catchments through the hydro-climatological pure time-series of a 14-year period from 2001 to 2015. Data sets encompass more than 13,000 month-station streamflow, rainfall, and temperature data obtained from 27 catchments in Utah State as one of the eight mountainous states of the USA. The identification, analysis, and interpretation of homogeneous catchments were investigated by applying the four approaches of clustering, K-means, Ward, and SOM (Self-Organized Map) and a newly proposed Wavelet-Entropy-based (WE-SOM) clustering method. By using two clustering evaluation criteria, 3, 5, and 6 clusters were determined as the best numbers of clusters, depending on the method employed, where each cluster represents different hydro-climatological behaviors. Despite the absence of geographic characteristics in input data matrix, the results indicated a regionalization in agreement with topographic characteristics. Considering the dependency of the hydrological behavior of catchments on the physiographic field aspects and characteristics, WE-SOM method demonstrated a more acceptable performance, compared to the other three conventional clustering methods, by providing more clusters. WE-SOM appears to be a promising approach in catchment clustering. It preserves the topological structure of data which can, as a result, be proofed in a greater number of clusters by dividing data into higher numbers of distinct clusters with similar altitudes of catchments in each cluster. The results showed the aptitude of wavelets to quantify the time-based variability of temperature, rainfall and streamflow, in the way contributing to the regionalization of diverse catchments. 相似文献
9.
The ability of fuzzy logic algorithms to model relationships between stream flow and suspended sediment discharge was investigated
using daily measurements of stream flow and suspended sediment discharge for the Escanaba River mouth station, situated on
the shore of Lake Michigan and operated by the US Geological Survey. Three different configurations of inputs were applied,
whereby the inputs were fuzzified into fuzzy subsets of variables by means of triangular membership functions. The relationships
between inputs and suspended sediment discharge (output) were represented by a set of fuzzy rule expressed in IF–THEN format.
The weighted average method served for defuzzification. The commonly used sediment rating curve was also applied to the data,
and its performance compared with that of the three models by means of statistical analyses. For all three models, suspended
sediment discharge predicted by the fuzzy logic algorithm was in satisfactory agreement with observations. Furthermore, the
fuzzy logic algorithms performed better than the sediment rating curve, particularly at higher rates of suspended sediment
discharge (in this study, more than 50 × 106 g/day). Considered collectively, the use of fuzzy logic algorithms is suggested as a simple and effective approach for better
prediction of suspended sediment discharge, also for estuaries. 相似文献
10.