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61.
In this paper a new approach is presented, based on evolutionary polynomial regression (EPR), for determination of liquefaction potential of sands. EPR models are developed and validated using a database of 170 liquefaction and non-liquefaction field case histories for sandy soils based on CPT results. Three models are presented to relate liquefaction potential to soil geometric and geotechnical parameters as well as earthquake characteristics. It is shown that the EPR model is able to learn, with a very high accuracy, the complex relationship between liquefaction and its contributing factors in the form of a function. The attained function can then be used to generalize the learning to predict liquefaction potential for new cases not used in the construction of the model. The results of the developed EPR models are compared with a conventional model as well as a number of neural network-based models. It is shown that the proposed EPR model provides more accurate results than the conventional model and the accuracy of the EPR results is better than or at least comparable to that of the neural network-based models proposed in the literature. The advantages of the proposed EPR model over the conventional and neural network-based models are highlighted. 相似文献
62.
Samira Mokhtari Asl Mohammadreza Jafari Reza Zarei Sahamiyeh Vahid Shahrokhi 《Arabian Journal of Geosciences》2015,8(9):7125-7139
Farsesh barite in the central part of Iranian Sanandaj-Sirjan zone is a sample of epigenetic hydrothermal mineralization in dolomitized limestone, which provides appropriate chemicophysical conditions making the passage of mineral-bearing fluids possible. Barite veins may range from a few centimeters to 2 m in thickness that increases downward. The microthermometry measurements obtained from more than 30 fluid inclusions show relative homogenization temperatures ranging from 125 to 200 °C with an average of 110 °C for Farsesh barite deposits. The mean salinity measured proves 16 times as much as weight percentage of NaCl for barite. Coexistence of liquid- and vapor-rich fluid inclusions in barite minerals may provide an evidence of boiling in ore veins. Moreover, occurrence of bladed calcite, high-grade ore zones, and presence of hydrothermal breccia are all consistent with boiling. Thermometric studies indicate that homogenization temperatures (Th) for primary and pseudosecondary fluid inclusions in barite range from 125 to 200 °C with an average of 1,100 °C. The δ34S values of barite also lie between 8.88 and 16.6 %. The relatively narrow spread in δ34S values may suggest uniform environmental conditions throughout the mineralization field. Thus, δ34S values are lower than those of contemporaneous seawater, which indicates a contribution of magmatic sulfur to the ore-forming solution. Barite is marked by total amounts of rare Earth elements (REEs) (6.25–17.39 ppm). Moreover, chondrite-normalized REE patterns of barite indicate a fractionation of light REEs (i.e., LREEs) from La to Sm, similar to those for barite from different origins. The LaCN/LuCN ratios and chondrite-normalized REE patterns reveal that barite in Farsesh deposit is enriched in LREEs compared with heavy rare Earth elements (HREEs). Similarity between Ce/La ratios in barite samples and those found in deep-sea barite supports its marine origin. Lanthanum and Gd exhibit positive anomalies, which are common features of chemical marine sediments. Cerium shows a negative anomaly in most samples inherited from the negative Ce anomaly of hydrothermal fluid that is mixed with seawater at barite precipitation. The available data including tectonic setting, host rock characteristics, REE geochemistry, and sulfur isotopic compositions may support a hydrothermal submarine origin for Farsesh barite deposit. 相似文献
63.
Maryam Azodi Eisa Ebrahimi Omidvar Farhadian Nasrollah Mahboobi-Soofiani Vahid Morshedi 《中国海洋湖沼学报》2015,33(4):928-933
This sixty-day study was performed to determine the effects of short-term starvation and refeeding cycles on growth, feeding performances and body composition of rainbow trout(O ncorhynchus mykiss). Three hundred trout fingerlings with an average initial weight of 17.5±0.06 g were randomly distributed in 15 circular fiberglass tanks. The fish were exposed to 5 different feeding regimes; control: continuously fed twice daily to apparent satiation; T1 : starved for 1 day and re-fed for 2 days; T2 : starved for 1 day and re-fed for 4 days; T3 : starved for 3 days and re-fed for 12 days; T 4 : starved for 4 days and re-fed for 16 days. At the end of the experiment, growth performance, feed utilization, whole body ash and moisture contents were not significantly(P 0.05) different among the treatments. However, whole body protein content in T3 was significantly higher than other treatments(P 0.05). A significant difference in whole body fat content was observed between T3 and the control group at the end of the experiment(P 0.05). In conclusion this experiment suggests that feeding schedules involving starvation(1–4 days) and re-feeding cycles are a promising feed management tool for rainbow trout culture. 相似文献
64.
Assessment of nitrate contamination in unsaturated zone of urban areas: The case study of Tehran,Iran 总被引：1，自引：0，他引：1
Modeling fate of nitrogen in unsaturated and saturated zone is a complex process, which requires detailed geochemical data.
Complexities of the process as well as data insufficiencies are two major issues, which make quantitative assessment of the
problem more complicated. In this work, a lumped-parameter model (LPM) is proposed that has been evaluated for a data-limited
case to study temporal and steady-state behavior of Nitrate and Ammonium in unsaturated zone. The concentration of components
in the model are assumed as the depth-averaged concentrations, and dispersive fluxes have been neglected. The case study area
is Tehran City aquifer, which is highly contaminated by domestic wastewater discharge into the groundwater. Three sources
for Nitrogen contamination have been studied, namely domestic wastewater, park/recreational applications, and wet deposition.
Results show that Nitrate production in the first few meters (<5 m) is quite large. To compare the model results with the
measurements, error estimation analysis based on Vornoi map has been fulfilled. Finally, it is shown that there is a fairly
good correlation coefficient between simulation and measurements, which approves the validity of the LPM. 相似文献
65.
A finite element technique is developed for two-dimensional problems of dynamics of dam–water–foundation systems taking into account all interactions rigorously. Water–foundation interaction, which previous developments have only simulated, is considered by imposing proper conditions at the fluid–solid interface. Furthermore, the technique permits treatment of layered foundations. An application to a concrete gravity dam–water–foundation system is presented and discussed. 相似文献
66.
Natural Resources Research - Groundwater level forecasting is a paramount necessity for integrated management of a basin. Development of suitable models is an essential step in determining... 相似文献
67.
From the viewpoint of safety in underground coal mining, the most suitable mining panel is the one with minimum geological structures, the right machinery, and equipment selection, trained employee, and proficient stope management. Since the ground parameters are uncontrollable and inherent uncertainties exist, a high percent of risk will usually accompany the underground coal mining activities. The main purpose of this study is to present a geological–geotechnical risk assessment model for identification of high risk-prone areas in underground coal mines using an integrated GIS-geostatistics system. Tabas as the first mechanized and largest underground coal mine in Iran was selected as a case study in this study. Gas content of coal seam, Coal Mine Roof Rating (CMRR), initial in situ stress state, fault throw, and orientation were selected as hazard/risk factors. For estimating the amount of coal seam gas content, CMRR and initial in situ stress in unsampled areas and providing the prediction maps, geostatistics module in ArcGIS was used. Rock engineering system–interaction matrix method was used for attribute weight assignment. Next, the attribute layers were weighted, rated, and overlaid to create a final map of geohazards risk. The analysis results of final risk map indicate that about 45% of under study area is prone to high to very high geohazards risk. Comparison of the results with experiences obtained during the early part of the mine and mined-out panels showed generally good agreement with promising ideas. This highlights the potential application of the GIS-based approach for hazards detection and geohazards risk assessment in underground coal mines. 相似文献
68.
69.
Mohammad?Ali?GhorbaniEmail author Ravinesh?C.?Deo Vahid?Karimi Zaher?Mundher?Yaseen Ozlem?Terzi 《Stochastic Environmental Research and Risk Assessment (SERRA)》2018,32(6):1683-1697
The predictive ability of a hybrid model integrating the Firefly Algorithm (FFA), as a heuristic optimization tool with the Multilayer Perceptron (MLP-FFA) algorithm for the prediction of water level in Lake Egirdir, Turkey, is investigated. The accuracy of the hybrid MLP-FFA model is then evaluated against the standalone MLP-based model developed with the Levenberg–Marquadt optimization scheme applied for in the backpropagation-based learning process. To develop and investigate the veracity of the proposed hybrid MLP-FFA model, monthly time scale water level data for 56 years (1961–2016) are applied to train and test the hybrid model. The input combinations of the standalone and the hybrid predictive models are determined in accordance with the Average Mutual Information computed from the historical water level (training) data; generating four statistically significant lagged combinations of historical data to be adopted for the 1-month forecasting of lake water level. The proposed hybrid MLP-FFA model is evaluated with statistical score metrics: Nash–Sutcliffe efficiency, root mean square and mean absolute error, Wilmott’s Index and Taylor diagram developed in the testing phase. The analysis of the results showed that the hybrid MLP–FFA4 model (where 4 months of lagged combinations of lake water level data are utilized) performed more accurately than the standalone MLP4 model. For the fully optimized hybrid (MLP-FFA4) model evaluated in the testing phase, the Willmott’s Index was approximately 0.999 relative to 0.988 (MLP 4) and the root mean square error was approximately 0.029 m and compared to 0.102 m. Moreover, the inter-comparison of the forecasted and the observed data with various other performance metrics (including the Taylor diagram) verified the robustness of the proposed hybrid MLP-FFA4 model over the standalone MLP4 model applied in the problem of forecasting lake water level prediction in the current semi-arid region in Turkey. 相似文献
70.
Surface sediments (n = 17) were collected from 6 sites located in the coasts of the Bushehr Peninsula. ∑16PAH concentrations were in the range of 285.9–1288 ng g? 1 dw and the sediments were moderately polluted. Py, Ph, B(a)A and Flu showed > 70% of the detected values in order of the mentioned rank. 4-ring PAHs were the dominant compounds and the molecular ratios presented the dominant pyrolytic source. The toxicity of PAHs for sediment dwelling life was averagely equivalent to occurrence of 0.08 ng g? 1 of Dioxin in dw of the examined sediments. The evaluated narcotic potential (confidence level of 99%) was 0.027–3.04 and upper part of the Bushehr Peninsula, where the human population is more concentrated, showed more narcotic potential. ∑ n-alkane concentrations (n-C15 ? n-C32) were in the range of 3.10–35.6 μg g? 1 dw. The dominant distribution of even carbon number n-alkanes was traced back to a possibly autochthonous source. 相似文献