Effects of groundwater table position,soil strength properties and rainfall on instability of earthquake-triggered landslides     

S. Amir Reza Beyabanaki  Amvrossios C. Bagtzoglou  Emmanouil N. Anagnostou 《Environmental Earth Sciences》2016,75(4):358

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Investigation of physicochemical parameters in drinking water resources and health risk assessment: a case study in NW Iran     

Malakootian  Mohammad  Mohammadi  Amir  Faraji  Maryam 《Environmental Earth Sciences》2020,79(9):1-13

In this study, the amount of cyanide in gold mine tailings is modeled as conceptual, statistical, and mathematical to determine environmental risk level and also to estimate the fate and transport of cyanide in tailings. Therefore, 116 points were selected for sampling from three levels of gold mine tailings and analyzed by colorimetric method. As a matter of fact, new hybrid modeling methods such as AdaBoost, Support Vector Machine, Linear Discriminant Analysis, and Random Forest were used in estimation. In current study, The AdaBoost method was qualified as the best one by minimum estimation error (less than 10%). The model derived from the AdaBoost method shows an average variation of 581 g/day in the volume of cyanide tailings. Thus, the important results of this paper are the presentation of 3D numerical and especially conceptual models according to the 3D cyanide variation in the sulfide gold mine tailings and governing physic/chemical parameters. These qualitative and quantitative results can be used for the management of tailings dam and prevention of the contaminant extension.  相似文献   

Changes in hydrodynamic process dominance (wave,tide or river) in foreland sequences: The subalpine Miocene Molasse revisited (France)     

Amir Kalifi  Philippe Sorrel  Philippe-Hervé Leloup  Vincenzo Spina  Bastien Huet  Albert Galy  Jean-Loup Rubino  Bernard Pittet 《Sedimentology》2020,67(5):2455-2501

A comprehensive sedimentological study was undertaken in the Miocene of the subalpine massifs and southern Jura (France) with the aim to constrain the evolution of process changes in third-order sequences of peripheral foreland basins during the overfilled phase (i.e. sediment supply higher than accommodation space). Fieldwork analyses based on 35 sedimentological sections allowed the identification of four depositional models: wave dominated, mixed wave-tide, river to tide and river dominated. The sections were dated using chemostratigraphy (i.e. marine strontium isotopic ratios), revealing three-third-order sequences between the Upper Aquitanian and the Langhian. Chronostratigraphical and sedimentological results document prominent and recurrent changes in depositional models along third-order sequences: (i) in the earliest stage of the transgression, mixed-energy coastal environments influenced by the local coastal morphology prevailed (in palaeo-highs or incised valleys); (ii) during the course of the transgression, Gilbert delta deposits suggest a prominent steepening linked to a tectonic uplift in the proximal depozone (between the tectonically active frontal part of the orogenic wedge and the proximal foredeep). Instead, in the distal depozone (between the proximal foredeep and the proximal border of the flexural uplifted forebulge), deposits were characterized either by wave-dominated or mixed wave-tide environments and are likely eustatically-driven; (iii) during the maximum flooding stage, water depth remained shallow below the storm-weather wave base; and (iv) during the regression, the proximal depozone is characterized by the progradation of gravel-rich fan deltas. In the distal depozone, mixed wave-tide systems preceded the development of river to tidal depositional environments. These results were integrated and compared with facies models from other basin analogues worldwide. A model tackling the evolution of process changes within third-order sequences (of the overfilled phase) of foreland basins is proposed, thereby improving sequence stratigraphic predictions in foreland basins.  相似文献   

Zoning map for drought prediction using integrated machine learning models with a nomadic people optimization algorithm     

Mohamadi  Sedigheh  Sammen  Saad Sh.  Panahi  Fatemeh  Ehteram  Mohammad  Kisi  Ozgur  Mosavi  Amir  Ahmed  Ali Najah  El-Shafie  Ahmed  Al-Ansari  Nadhir 《Natural Hazards》2020,104(1):537-579

Natural Hazards - The modelling of drought is of utmost importance for the efficient management of water resources. This article used the adaptive neuro-fuzzy interface system (ANFIS), multilayer...  相似文献   

Effect of Orientation on the Variability Pattern of Gamma-Ray Sources     

Amir Levinson 《Astrophysics and Space Science》1999,268(4):433-441

Using a toy model, we demonstrate how the variability pattern of a relativistically moving source of radiation that is subject to the action of a transient force, depends on dynamical effects. The model is motivated by a recent analysis of radiative fronts in magnetized, relativistic jets, but is applicable also in other situations. The main effect analyzed in this paper is the strong dependence of the variability pattern on viewing angle, resulting from changes of the beaming cone of emission. In particular, it is shown that(1) the shape of the light curves reflects the time profile of the Doppler factor when viewing the source at large enough angles to its direction of motion, whereas at small viewing angles it is determined by the time evolution of the radiated power density; and(2) the characteristics of correlated emission depend strongly on viewing angle by virtue of either optical depth effects or the difference in beaming patterns of different radiation sources. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Reservoir water level forecasting using group method of data handling   总被引：1，自引：0，他引：1  

Amir Hossein Zaji  Hossein Bonakdari  Bahram Gharabaghi 《Acta Geophysica》2018,66(4):717-730

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Effects of metallic system components on marine electromagnetic loop data     

Konstantin Reeck  Hendrik Müller  Sebastian Hölz  Amir Haroon  Katrin Schwalenberg  Marion Jegen 《Geophysical Prospecting》2020,68(7):2254-2270

Electromagnetic loop systems rely on the use of non-conductive materials near the sensor to minimize bias effects superimposed on measured data. For marine sensors, rigidity, compactness and ease of platform handling are essential. Thus, commonly a compromise between rigid, cost-effective and non-conductive materials (e.g. stainless steel versus fibreglass composites) needs to be found. For systems dedicated to controlled-source electromagnetic measurements, a spatial separation between critical system components and sensors may be feasible, whereas compact multi-sensor platforms, remotely operated vehicles and autonomous unmanned vehicles require the use of electrically conductive components near the sensor. While data analysis and geological interpretations benefit vastly from each added instrument and multidisciplinary approaches, this introduces a systematic and platform-immanent bias in the measured electromagnetic data. In this scope, we present two comparable case studies targeting loop-source electromagnetic applications in both time and frequency domains: the time-domain system trades the compact design for a clear separation of 15 m between an upper fibreglass frame, holding most critical titanium system components, and a lower frame with its coil and receivers. In case of the frequency-domain profiler, the compact and rigid design is achieved by a circular fibreglass platform, carrying the transmitting and receiving coils, as well as several titanium housings and instruments. In this study, we analyse and quantify the quasi-static influence of conductive objects on time- and frequency-domain coil systems by applying an analytically and experimentally verified 3D finite element model. Moreover, we present calibration and optimization procedures to minimize bias inherent in the measured data. The numerical experiments do not only show the significance of the bias on the inversion results, but also the efficiency of a system calibration against the analytically calculated response of a known environment. The remaining bias after calibration is a time/frequency-dependent function of seafloor conductivity, which doubles the commonly estimated noise floor from 1% to 2%, decreasing the sensitivity and resolution of the devices. By optimizing size and position of critical conductive system components (e.g. titanium housings) and/or modifying the transmitter/receiver geometry, we significantly reduce the effect of this residual bias on the inversion results as demonstrated by 3D modelling. These procedures motivate the opportunity to design dedicated, compact, low-bias platforms and provide a solution for autonomous and remotely steered designs by minimizing their effect on the sensitivity of the controlled-source electromagnetic sensor.  相似文献   

Step-on versus step-off signals in time-domain controlled source electromagnetic methods using a grounded electric dipole     

Amir Haroon  Andrei Swidinsky  Sebastian Hölz  Marion Jegen  Bülent Tezkan 《Geophysical Prospecting》2020,68(9):2825-2844

The time-domain controlled source electromagnetic method is a geophysical prospecting tool applied to image the subsurface resistivity distribution on land and in the marine environment. In its most general set-up, a square-wave current is fed into a grounded horizontal electric dipole, and several electric and magnetic field receivers at defined offsets to the imposed current measure the electromagnetic response of the Earth. In the marine environment, the application often uses only inline electric field receivers that, for a 50% duty-cycle current waveform, include both step-on and step-off signals. Here, forward and inverse 1D modelling is used to demonstrate limited sensitivity towards shallow resistive layers in the step-off electric field when transmitter and receivers are surrounded by conductive seawater. This observation is explained by a masking effect of the direct current signal that flows through the seawater and primarily affects step-off data. During a step-off measurement, this direct current is orders of magnitude larger than the inductive response at early and intermediate times, limiting the step-off sensitivity towards shallow resistive layers in the seafloor. Step-on data measure the resistive layer at times preceding the arrival of the direct current signal leading to higher sensitivity compared to step-off data. Such dichotomous behaviour between step-on and step-off data is less obvious in onshore experiments due to the lack of a strong overlying conductive zone and corresponding masking effect from direct current flow. Supported by synthetic 1D inversion studies, we conclude that time-domain controlled source electromagnetic measurements on land should apply both step-on and step-off data in a combined inversion approach to maximize signal-to-noise ratios and utilize the sensitivity characteristics of each signal. In an isotropic marine environment, step-off electric fields have inferior sensitivity towards shallow resistive layers compared to step-on data, resulting in an increase of non-uniqueness when interpreting step-off data in a single or combined inversion.  相似文献   

Responses in Phenotypic Plasticity of Amaranthus palmeri and Polygonum orientale to Soil Factors under Different Habitats     

Mei Zhang  Kexin Ma  Tong Liu  Lili Tang  Amir Abdullah Khan  Tong Yang  Pufan Zheng  Tongtong Wang  Jianhua Han  Fuchen Shi 《洁净——土壤、空气、水》2020,48(1)

The extension and structure of functional traits variation in response to different soil factors between invasive and native plants are poorly understood. Functional traits and soil factors of the invasive plant Amaranthus palmeri and its coexisting plant Polygonum orientale are investigated under three heterogeneous habitats: roadside (rs), wasteland (wl), and riverbank (rb) in Tianjin, China. The shoot dry weight (SDW) and leaf nitrogen (LN) of A. palmeri are significantly higher compared with P. orientale, while A. palmeri has significantly lower leaf dry weight (LDW), leaf area (LA), leaf carbon (LC), and leaf C/N ratio under different habitats. The larger phenotypic plasticity of A. palmeri is one of the important reasons for their successful invasion to heterogeneous habitats. Similarly, the soil water content (SWC) of both species shows a significant difference (p < 0.05) with maximum in riverbank habitat to lowest in roadside habitat. Soil N/P ratio, C/N ratio, and C/P ratio of rb habitats are significantly lower compared to wl and rs habitats (p < 0.05). A redundancy analysis indicates that SWC is the dominant soil factor affecting the functional traits of A. palmeri and P. orientale. However, A. palmeri forms an environmental adaptation strategy by changing traits of SDW, LN, and leaf C/N ratio, which is different from P. orientale by changing traits of LA and LDW.  相似文献   

Minimum‐cost optimization of nonlinear fluid viscous dampers and their supporting members for seismic retrofitting          下载免费PDF全文

Nicolò Pollini  Oren Lavan  Oded Amir 《地震工程与结构动力学》2017,46(12):1941-1961

This paper presents an effective approach for achieving minimum‐cost designs for seismic retrofitting using nonlinear fluid viscous dampers. The damping coefficients of the dampers and the stiffness coefficients of the supporting braces are designed by an optimization algorithm. A realistic retrofitting cost function is minimized subject to constraints on inter‐story drifts at the peripheries of frame structures. The cost function accounts for costs related to both the topology and the sizes of the dampers. The behavior of each damper‐brace element is defined by the Maxwell model, where the force–velocity relation of the nonlinear dampers is formulated with a fractional power law. The optimization problem is first posed and solved as a mixed integer problem. For the reduction of the computational effort required in the optimization, the problem is then reformulated with continuous variables only and solved with a gradient‐based algorithm. Material interpolation techniques, which have been successfully applied in topology optimization and in multi‐material optimization, play a key role in achieving practical final design solutions with a reasonable computational effort. Promising results attained for 3‐D irregular frames are presented and discussed. Copyright © 2017 John Wiley & Sons, Ltd.  相似文献