Mineralogical,geochemical, fluid inclusion and isotope study of Hohentauern/Sunk sparry magnesite deposit (Eastern Alps/Austria): implications for a metasomatic genetic model     

Amir M. Azim Zadeh  Fritz Ebner  Shao-Yong Jiang 《Mineralogy and Petrology》2015,109(5):555-575

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A comparative study of support vector machines and artificial neural networks for predicting precipitation in Iran     

Omid Hamidi  Jalal Poorolajal  Majid Sadeghifar  Hamed Abbasi  Zohreh Maryanaji  Hamid Reza Faridi  Lily Tapak 《Theoretical and Applied Climatology》2015,119(3-4):723-731

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Estimation of the Amount of Suspended Sediment in the Tigris River using Artificial Neural Networks     

Nizamettin Hamidi  Necati Kayaalp 《洁净——土壤、空气、水》2008,36(4):380-386

The amount of sediment should be taken into consideration in the planning of water structures for efficient use of limited water resources. It is important to estimate the amount of sediment for the successful operation of these structures in their future performances. Such estimations can be achieved by Artificial Neural Network (ANNs) with low error percentages as seen in many other disciplines. These networks also enable the modeling of nonlinear relationships between the parameters affecting the event. The purpose of this research is to establish models for sediment amounts in the Tigris River at the Diyarbakir measurement station in Turkey. Rainfall, temperature and discharge are taken as independent variables in the models, whereas sediment is taken as the dependent variable. Fourteen different models are generated using ANNs and Regression Analysis (RA). The results are compared with each other and with the observed data. The relative error and determination coefficient are used as comparison criteria. It is concluded that due to their nonlinear modeling capability, ANNs give better results than RA.  相似文献   

Kuh-e Dom Fe–Cu–Au prospect,Anarak Metallogenic Complex,Central Iran: a geological,mineralogical and fluid inclusion study     

Ebrahim Tale Fazel  Behzad Mehrabi  Amir Ali Tabbakh Shabani 《Mineralogy and Petrology》2015,109(1):115-141

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Investigation of hydraulics transport time scales within the Arvand River estuary,Iran          下载免费PDF全文

Amir Etemad‐Shahidi  Mostafa Pirnia  Hengameh Moshfeghi  Charles Lemckert 《水文研究》2014,28(25):6006-6015

Transport time scales are key parameters for understanding the hydrodynamic and biochemical processes within estuaries. In this study, the flushing and residence times within the Arvand River estuary have been estimated using a two‐dimensional hydrodynamic model called CE‐QUAL‐W2. The model has been calibrated and verified by two different sets of field data and using the k‐ε vertical eddy diffusivity scheme. Flushing time has been estimated using different methods such as the tidal prism and fraction of freshwater methods. Moreover, residence times have been investigated using pulse residence time, estuarine residence time and remnant function approaches. The results have shown that different methods yield different time scales, and freshwater inflow has the greatest impact upon estimation of residence time, whereas tidal circulation hardly contributes to residence time at all. It has also been shown that the neap‐spring circulation and start phase of simulations have negligible effects on the Arvand's time scales. The investigation of bathymetry showed that two sills of the estuary tend to significantly increase residence time. Understanding the applicability of these time scales and their estimation approaches helps us to evaluate the water quality management of estuaries. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

Capabilities of satellite precipitation datasets to estimate heavy precipitation rates at different temporal accumulations          下载免费PDF全文

Ali Mehran  Amir AghaKouchak 《水文研究》2014,28(4):2262-2270

The importance of satellite datasets as alternative sources of precipitation information has been argued in numerous studies. Future developments in satellite precipitation algorithms as well as utilization of satellite data in operational applications rely on a more in‐depth understanding of satellite errors and biases across different spatial and temporal scales. This paper investigates the capability of satellite precipitation data sets with respect to detecting heavy precipitation rates over different temporal accumulations. In this study, the performance of Tropical Rainfall Measuring Mission real time (TRMM‐RT), Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks and CPC MORPHing (CMORPH) is compared against radar‐based gauge‐adjusted Stage IV data. The results show that none of the high temporal resolution (3‐h) datasets are ideal for detecting heavy precipitation rates. In fact, the detection skill of all products drops as the precipitation thresholds (i.e. 75 and 90 percentiles) increase. At higher temporal accumulations (6, 12 and 24 h), the detection skill improves for all precipitation products, with CMORPH showing a better detection skill compared to all other products. On the other hand, all precipitation products exhibit high false alarm ratios above the heavy precipitation thresholds, although TRMM‐RT lead to a relatively smaller level of false alarms. These results indicate that further efforts are necessary to improve the precipitation algorithms so that they can capture heavy precipitation rates more reliably. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

Characterization by electrical and electromagnetic geophysical methods of the shallow hydrogeological system at Hebron (West Bank,Palestine) in a semi-arid zone     

Asal Sirhan  Mohammad O. Hamidi 《Comptes Rendus Geoscience》2012,344(9):449-460

Multi-electrode geo-electrical and transient electromagnetic surveys were carried out to characterize the nature of the subsurface infiltration zones (5 to 20 m) related to a series of groundwater outlets, and to reveal the geometry of the different aquifers at Bani-Naim, in the south-eastern foothills of the Hebron area, West Bank, Palestine. The purpose of the surveys was to understand the link between water storage/transfer and the characteristics of the geological formations. The strata in this semi-arid region are composed of alternate layers of chalky limestone, hard limestone, marl and chalk. A total of 30 ERT and 15 TDEM were conducted at Bani Naim-Jahir and Bani Naim-Birein. A correlation between the results indicates various infiltration pathways: fractures, feature heterogeneities, and porous chalk. The local heterogeneity on the eastern side were the major pathways for the water infiltration, whereas the thick marl layer underneath acts as a natural impermeable barrier preventing water from infiltrating deeper. A combination of the different geophysical results identified conductive features that correspond to the infiltration zones supplying the dug wells with water. Furthermore, it was established that the fractured chalk and porous chalky limestone act as an aquifer. A three-dimensional visualization of the resistivity allowed a useful reconstruction of the shallow hydrogeological system. Consequently, these studies contribute to regional sustainable development projects in this semi-arid region.  相似文献   

Robust attenuation relations for peak time-domain parameters of strong ground motions     

Ali Kafaei Mohammadnejad  Seyyed Mohammad Mousavi  Mohammad Torabi  Mehdi Mousavi  Amir Hossein Alavi 《Environmental Earth Sciences》2012,67(1):53-70

This study presents new attenuation models for the estimation of peak ground acceleration (PGA), peak ground velocity (PGV), and peak ground displacement (PGD) using a hybrid method coupling genetic programming and simulated annealing, called GP/SA. The PGA, PGV, and PGD were formulated in terms of earthquake magnitude, earthquake source to site distance, average shear-wave velocity, and faulting mechanisms. A worldwide database of strong ground motions released by Pacific Earthquake Engineering Research Center (PEER) was employed to establish the models. A traditional genetic programming analysis was performed to benchmark the proposed models. For more validity verification, the GP/SA models were employed to predict the ground-motion parameters of the Iranian plateau earthquakes. Sensitivity and parametric analyses were carried out and discussed. The results show that the GP/SA attenuation models can offer precise and efficient solutions for the prediction of estimates of the peak time-domain characteristics of strong ground motions. The performance of the proposed models is better than or comparable with the attenuation relationships found in the literature.  相似文献   

A mixture spatial point pattern model for the quasar luminosity function     

Amir T. Payandeh Najafabadi  Fatemeh Baniasadi 《New Astronomy》2011,16(6):386-390

Consider the problem of estimating the Quasar Luminosity Function (QLF). In a 2007 Ph.D. dissertation, Hugeback considers the QLF as a nonhomogeneous poisson process and estimates the intensity function under SDSS DR3 data (The University of Chicago, AAT 3273021). The present study follows Hugeback’s approach but introduces a mixture component which improves Hugeback’s model in several respects. Namely, the database is partitioned into two groups according to redshift: z < 2.75 and z ? 2.75. Next, a mixture model for the QLF was derived using the concept of pseudolikelihood, the addition of a K function to allow for inter-point interaction, and evaluation of residuals diagnostic plots. This mixture model (i) improves the deviance of Hugeback’s model, and (ii) satisfies residual assumptions that are violated under Hugeback’s model. Moreover, this study confirms Hugeback’s finding of inhomogeneity in the QLF, and provides stronger evidence for the existence of an interaction between redshift and absolute magnitude.  相似文献   

Laboratory experiments of tsunami run-up and withdrawal in patchy coastal forest on a steep beach   总被引：1，自引：0，他引：1  

Jennifer L. Irish  Robert Weiss  Yongqian Yang  Youn Kyung Song  Amir Zainali  Roberto Marivela-Colmenarejo 《Natural Hazards》2014,74(3):1933-1949

Laboratory experiments were carried out to study tsunami flow dynamics in the presence of patchy macro-roughness, representing coastal forest, on a 1:10 steep beach. The experimental setup included four cross-shore rows of roughness patches affixed to the dry beach in a staggered array, such that 12 % of the staggered array region had higher roughness. The flow field during run-up and withdrawal was quantified using point measurements of velocity and flow depth at 20 locations, while high-resolution video was used to track bore position during run-up. Data analysis revealed that while inundated area was marginally impacted when patchy roughness was present, flow depths and flow force were, respectively, increased by more than 40 and 30 % in some areas within the patch array; a decrease in flow force was also observed in some areas. Alongshore variation in flow depth, induced by the roughness patches, was most pronounced during withdrawal. These findings suggest that patchy macro-roughness, like that created by coastal forest, will simultaneously lead to increased protection in some areas and decreased protection in others.  相似文献