Comparison of ordinary kriging and artificial neural network for spatial mapping of arsenic contamination of groundwater   总被引：3，自引：2，他引：1  

Mohammad Chowdhury  Ali Alouani  Faisal Hossain 《Stochastic Environmental Research and Risk Assessment (SERRA)》2010,24(1):1-7

In this technical note, we investigate the hypothesis that ‘non-linearity matters in the spatial mapping of complex patterns of groundwater arsenic contamination’. The spatial mapping pertained to data-driven techniques of spatial interpolation based on sampling data at finite locations. Using the well known example of extensive groundwater contamination by arsenic in Bangladesh, we find that the use of a highly non-linear pattern learning technique in the form of an artificial neural network (ANN) can yield more accurate results under the same set of constraints when compared to the ordinary kriging method. One ANN and a variogram model were used to represent the spatial structure of arsenic contamination for the whole country. The probability for successful detection of a well as safe or unsafe was found to be atleast 15% larger than that by kriging under the country-wide scenario. The probability of false hopes, which is a serious issue in public health monitoring was found to be significantly lower (by more than 10%) than that by kriging.  相似文献   

Fuzzy control of piezoelectric friction dampers for seismic protection of smart base isolated buildings   总被引：1，自引：0，他引：1  

Osman E. Ozbulut  Stefan Hurlebaus 《Bulletin of Earthquake Engineering》2010,8(6):1435-1455

This study proposes two fuzzy logic controllers (FLCs) for operating control force of piezoelectric friction dampers used for seismic protection of base-isolated buildings against various types of earthquake excitations. The first controller employs a hierarchic control strategy in which a higher-level supervisory controller operates a single sub-level FLC by modifying its input normalization factors in order to determine command voltage of the damper according to current level of ground motion. The second controller is a self organizing FLC that employs genetic algorithms in order to build a knowledge base for the fuzzy controller. Numerical simulations of a base-isolated building are conducted to evaluate the performance of the controllers. For comparison purposes, an optimal controller is also developed and considered in the simulations together with maximum passive operation of the friction damper. Results for several historical ground motions show that developed fuzzy logic controllers can effectively reduce isolation system deformations without the loss of potential advantages of seismic base isolation.  相似文献   

Removal of the Alphazurine FG Dye from Simulated Solution by Electrocoagulation     

Ali Olad  Ali Reza Amani‐Ghadim  Mir Saeed Seyed Dorraji  Mohammad Hosein Rasoulifard 《洁净——土壤、空气、水》2010,38(4):401-408

The removal of Alphazurine FG (AF) dye from water by an electrocoagulation process has been studied. The effect of some operational parameters, such as anode material, current density, initial dye concentration, pH of solution, conductivity, and inter‐electrode distance, on the removal efficiency was investigated. Iron and aluminum were used as anodes in the electrocoagulation cell. It was found that the efficiency of the iron anode was better than that of the aluminum anode for AF removal. The factors that affected the removal efficiency were the current density and the initial dye concentration. The removal efficiency increased from about 35% at 25 A m^–2 to about 97% at 100 A m^–2, during 4 min of electrocoagulation. The results exhibited pseudo‐first‐order kinetics for AF removal by electrocoagulation. In addition, a mathematical model was successfully established for predicting the removal efficiency. A comparison between the model results and experimental data gave a high correlation coefficient (R² = 0.9925), which indicates that the model is able to predict the removal efficiency of AF.  相似文献   

Solar forcing on antarctic terrestrial climate: A study by means of GPS observations     

Wayan Suparta  Baharudin Yatim  Mohd A. Mohd Ali 《Acta Geophysica》2010,58(2):374-391

With a view to difficulties with explaining the physical mechanism of solar forcing on the Earth’s climate, we applied a new approach of determining and quantifying an influence of solar-related events on water vapor variability by correlating the total electron content (TEC) and precipitable water vapor (PWV), both derived from ground-based GPS observations. In this study, ionospheric TEC and atmospheric PWV values are employed as solar activity and terrestrial climate parameters, respectively. Three-year GPS data at five stations in Antarctica are analyzed on a daily mean basis. Results show significant correlation between TEC and PWV differences during storms-affected days. The high correlation between the daily mean values of TEC and PWV, both of which follow the seasonal signals and subsisting downward trend, suggests an influence of solar activity on climate variability in Antarctica. These quantities are determined by changes of the upper-atmosphere level, which varies in conformity with the zenith angle of the Sun.  相似文献   

Geochemistry and petrology of garnet‐bearing S‐type Shir‐Kuh Granite,southwest Yazd,Central Iran     

Mariyam Sheibi  Dariush Esmaeily  Ann Nédélec  Jean Luc Bouchez  Ali Kananian 《Island Arc》2010,19(2):292-312

The Jurassic Shir‐Kuh granitoid batholith in Central Iran intrudes Lower Jurassic sandstones and shales. The batholith consists of three main facies: (i) a granodioritic facies to the north; (ii) a monzogranitic facies spread throughout the batholith; and (iii) a leucogranitic facies along the northwestern margin. The granodiorites are composed mainly of plagioclase, quartz, K‐feldspar, biotite, and some muscovite, garnet, cordierite, ilmenite, zircon, apatite, and monazite. This facies contains variable amounts of restite minerals which are mainly defined by calcic plagioclase cores and small aggregates of biotite. The monzogranites, with mineral assemblages similar to those in the granodiorites, range from relatively mafic (cordierite‐bearing) to felsic (muscovite‐rich) rocks. The leucogranites, exposed as small stock and dykes, consist mainly of quartz, K‐feldspar, and sodic plagioclase. The batholith is peraluminous, calc‐alkaline, and typical of S‐type, as indicated by Na₂O content (2.74%), molecular Al₂O₃/(CaO + Na₂O + K₂O) (A/CNK) ratio (1.17), K₂O/Na₂O ratio (1.39), and isotopic data ([⁸⁷Sr/⁸⁶Sr]_i = 0.715). The rocks are characterized by enrichment in large ion lithophile elements such as Rb, Th and K and depletion in high field strength elements such as Nb and Ti. Chondrite‐normalized rare earth element (REE) patterns are characterized by light rare earth element (LREE) enrichment, with values of (La/Yb)_N between 4.5 and 19.53, unfractionated heavy rare earth element (HREE) with values of (Gd/Yb)_N between 0.98 and 2.88, and a distinct negative Eu. The parental magma of the Shir‐Kuh Granite was derived from a plagioclase‐rich metasedimentary source (local anatexis of metagreywacke) in the crust, with heat input from mantle melt components. The separation of restite crystals from the primary melt followed by the fractional crystallization appears to have been an effective differentiation process in the batholith.  相似文献   

Heavy Metal Bioaccumulation in Native Plants in Chromite Impacted Sites: A Search for Effective Remediating Plant Species          下载免费PDF全文

Javed Nawab  Mohammad Tahir Shah  Nayab Gul  Abid Ali  Kifayatullah Khan  Qing Huang 《洁净——土壤、空气、水》2016,44(1):37-46

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Low Density Solvent Ion Pair Dispersive Liquid–Liquid Micro‐Extraction – An Economic Method for Extraction of Phthalic Acids          下载免费PDF全文

Mir Ali Farajzadeh  Mohammad Reza Afshar Mogaddam 《洁净——土壤、空气、水》2016,44(11):1531-1537

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Adaptive multi‐rate interface: development and experimental verification for real‐time hybrid simulation          下载免费PDF全文

Amin Maghareh  Jacob P. Waldbjørn  Shirley J. Dyke  Arun Prakash  Ali I. Ozdagli 《地震工程与结构动力学》2016,45(9):1411-1425

Real‐time hybrid simulation (RTHS) is a powerful cyber‐physical technique that is a relatively cost‐effective method to perform global/local system evaluation of structural systems. A major factor that determines the ability of an RTHS to represent true system‐level behavior is the fidelity of the numerical substructure. While the use of higher‐order models increases fidelity of the simulation, it also increases the demand for computational resources. Because RTHS is executed at real‐time, in a conventional RTHS configuration, this increase in computational resources may limit the achievable sampling frequencies and/or introduce delays that can degrade its stability and performance. In this study, the Adaptive Multi‐rate Interface rate‐transitioning and compensation technique is developed to enable the use of more complex numerical models. Such a multi‐rate RTHS is strictly executed at real‐time, although it employs different time steps in the numerical and the physical substructures while including rate‐transitioning to link the components appropriately. Typically, a higher‐order numerical substructure model is solved at larger time intervals, and is coupled with a physical substructure that is driven at smaller time intervals for actuator control purposes. Through a series of simulations, the performance of the AMRI and several existing approaches for multi‐rate RTHS is compared. It is noted that compared with existing methods, AMRI leads to a smaller error, especially at higher ratios of sampling frequency between the numerical and physical substructures and for input signals with high‐frequency content. Further, it does not induce signal chattering at the coupling frequency. The effectiveness of AMRI is also verified experimentally. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

Physically based modelling of sheet erosion (detachment and deposition processes) in complex hillslopes   总被引：1，自引：0，他引：1       下载免费PDF全文

Ali Talebi  Rasoul Hajiabolghasemi  Mohamad Reza Hadian  Nosratollah Amanian 《水文研究》2016,30(12):1968-1977

A one‐dimensional uncoupled model governed by this research is a physics‐based modelling of the rainfall‐runoff induced erosion process. The presented model is composed of three parts of a three‐dimensional (3D) hillslope geometry, a nonlinear storage (kinematic wave) model for hillslope hydrological response, and an unsteady physically based surface erosion model. The 3D hillslope geometry model allows describing of the hillslope morphology by defining their plan shape and profile curvature. By changing these two topographic parameters, nine basic hillslope types are derived. The modelling of hillslope hydrological response is based on a flow continuity equation as the relation of discharge and flow depth is passed on kinematic wave approximation. The erosion model is based on a mass conservation equation for unsteady flow. The model assumes that suspended sediment does not affect flow dynamics. The model also accounts for the effect of flow depth plus loose soil depth on soil detachment. The presented model was run for two different precipitations, slope content, and length, and results were plotted for sediment detachment/deposition rate. Based on the obtained results, in hillslopes with convex and straight profile curvatures, sediment detachment only occurred in the whole length of the hillslope. However, in concave ones, sediment detachment and deposition only occurred together in hillslope. The hillslopes with straight profiles and convergent plans have the highest rate of detachment. Also, results show that most detachment rates occur in convex profile curvatures, which are about 15 times more than in straight profiles. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

Investigation into regional thermal structure of the Thrace Region, NW Turkey, from aeromagnetic and borehole data   总被引：1，自引：0，他引：1  

Z. Mümtaz Hisarli  M. Nuri Dolmaz  Mahmut Okyar  Ali Etiz  Naci Orbay 《Studia Geophysica et Geodaetica》2012,56(1):269-291

The aeromagnetic values over the study region are relatively uniform except for a few anomalies in the northeastern and southwestern areas. Analyses of aeromagnetic data were performed in NW Turkey, in order to have a look into the subsurface regional thermal structure of the region. For this purpose, power spectra, reduced to pole (RTP), and band-pass filtered anomalies were produced using geophysical techniques. Band-pass filtered data were produced from the RTP aeromagnetic anomalies to isolate near surface and undesired deep effects. Based on the aeromagnetic data interpretation, the thickness of the magnetized crust, named the Curie Point Depth (CPD), in the study area lies between 9.7 and 20.3 km. The CPD estimates in the Thrace region of Turkey indicate two shallow CPD (SCPD1 and SCPD2) zones (the Istranca Massif and the Saros Graben area). The deep CPD are located within the Thrace Basin with sediment thickness of about 9 km. The corresponding heat flow map prepared from the averaged thermal conductivities and thermal gradients from the CPD reveals the existence of one low heat flow zone (75 mW/m²) over the center of Thrace Basin, and two high heat flow zones over the Istranca Masif (100–125 mW/m²) in the northern side and Saros Graben (125–135 mW/m²) areas in the southern side of the Thrace Basin.  相似文献