Investigating the nexus of climate,energy, water,and land at decision-relevant scales: the Platform for Regional Integrated Modeling and Analysis (PRIMA)     

Ian Kraucunas  Leon Clarke  James Dirks  John Hathaway  Mohamad Hejazi  Kathy Hibbard  Maoyi Huang  Chunlian Jin  Michael Kintner-Meyer  Kerstin Kleese van Dam  Ruby Leung  Hong-Yi Li  Richard Moss  Marty Peterson  Jennie Rice  Michael Scott  Allison Thomson  Nathalie Voisin  Tristram West 《Climatic change》2015,129(3-4):573-588

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Diffuse instabilities with transition to localization in loose granular materials     

Richard Wan  Mauricio Pinheiro  Ali Daouadji  Mohamad Jrad  Félix Darve 《国际地质力学数值与分析法杂志》2013,37(10):1292-1311

This paper is concerned with diffuse and other ensuing failure modes in geomaterials when tested under homogeneous states of shearing in various loading programs and drainage conditions. Material instability is indeed the basic property that accounts for the instability of an initially homogeneous deformation field leading to diffuse failure and strain localization in geomaterials. The former is normally characterized by a runaway type of failure accompanied with a sudden and violent collapse of the material in the absence of any localization phenomena. Against this backdrop, we present a brief overview of material instability in elastoplastic solids where one finds a rich source of theoretical concepts including bifurcation, strain localization, diffuse failure and second‐order work, as well as a considerable body of experiments. Some compelling laboratory experimental studies of material instability with focus to diffuse failure are then presented and interpreted based on the second‐order work. Finally, various material instability analyses using an elastoplastic constitutive and a general finite element analysis of the above‐mentioned laboratory experimental tests are presented as a boundary value problem. It is shown that instability can be captured from otherwise uniform stress, density and hydraulic states, whereas uniform deviatoric loads are being applied on the external boundaries of a specimen. Although the numerical simulations reproduce well the laboratory experimental results, they also highlight the hierarchy of failure modes where localization phenomena emerge in the post‐bifurcation regime as a result of a degradation of homogeneity starting from a diffuse mode signalled by a zero second‐order work. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

The impact of climate change on sea level rise at Peninsular Malaysia and Sabah–Sarawak     

Ali Ercan  Mohd Fauzi Bin Mohamad  M. Levent Kavvas 《水文研究》2013,27(3):367-377

The sea level change along the Peninsular Malaysia and Sabah–Sarawak coastlines for the 21st century is investigated along the coastal areas of Peninsular Malaysia and Sabah–Sarawak because of the expected climate change during the 21st century. The spatial variation of the sea level change is estimated by assimilating the global mean sea level projections from the Atmosphere–Ocean coupled Global Climate Model/General Circulation Model (AOGCM) simulations to the satellite altimeter observations along the subject coastlines. Using the assimilated AOGCM projections, the sea level around the Peninsular Malaysia coastline is projected to rise with a mean in the range of 0.066 to 0.141 m in 2040 and 0.253 m to 0.517 m in 2100. Using the assimilated AOGCM projections, the sea level around Sabah–Sarawak coastlines is projected to rise with a mean in the range of 0.115 m to 0.291 m in 2040 and 0.432 m to 1.064 m in 2100. The highest sea level rise occurs at the northeast and northwest regions in Peninsular Malaysia and at north and east sectors of Sabah in Sabah–Sarawak coastline. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

Bearing capacity of sandy soil treated by Kenaf fibre geotextile     

Ahmad Safuan A. Rashid  Mohammad Gharehzadeh Shirazi  Hisham Mohamad  Fauzan Sahdi 《Environmental Earth Sciences》2017,76(12):431

Bio-based materials are widely used recently in order to introduce a more sustainable construction material. Kenaf is a type of bio-based material that can be easily obtained in a tropical country, which could be a potential material to be utilised as a geotextile material because it has good tensile strength. The geotextile could be used to improve the bearing capacity of a loose soil. This paper presents a series of small-scale physical modelling tests to investigate the bearing capacity performance of Kenaf fibre geotextile laid on and inside the sand layer. A rigid footing was used to replicate a strip footing during the loading test, and sand was prepared based on 50% of relative density in a rigid testing chamber for ground model preparation. In order to treat the soil, Kenaf fibre geotextile was laid at four difference locations which are on the soil surface and underneath the ground model surface at 50, 75 and 100 mm deep. It was found that the usage of the Kenaf fibre geotextile has improved the bearing capacity of the sandy soil up to 414.9% as compared to untreated soil. It was also found that the depth of the Kenaf fibre geotextile treated into the soil also affects the soil performance.  相似文献   

Experimental and analytical evaluation of the consolidation of tower 8 in the Damascus citadel     

Mayada Al-kousa  Hala Tawfiq Hasan  Mohamad khir Abdul-wahed  Maissa Alarab  Idmon Al-egy 《Arabian Journal of Geosciences》2017,10(2):37

The object of this work is a building situated in the ancient citadel of Damascus: tower 8 which has been affected by devastating earthquakes and subjected to a consolidation process thanks to the Syrian–Italian Cooperation Project. The aim of this research is to investigate the dynamic characteristics of this consolidated structure. Hence, a mixed procedure of experimental measurements and analytical analysis has been chosen. Considering the geotectonic environment and the historical importance, ambient noise measurements are preferred as being a non-destructive technique and the most suitable for the study purpose. The dynamic characteristics of tower 8 are analyzed experimentally and analytically on the basis of ambient noise measurements, which have been performed on the ground and floors of the tower. With spectral analysis of ambient noise records, the predominant frequencies, amplification factors, and damping ratios have been determined. The experimental and analytical results have allowed verifying the efficiency of the consolidation interventions in tower 8.  相似文献   

Comparison of artificial neural networks,geographically weighted regression and Cokriging methods for predicting the spatial distribution of soil macronutrients (N,P, and K)   总被引：2，自引：1，他引：1  

Samad Emamgholizadeh  Shahin Shahsavani  Mohamad Amin Eslami 《中国地理科学(英文版)》2017,27(5):747-759

Soil macronutrients(i.e. nitrogen(N), phosphorus(P), and potassium(K)) are important soils components and knowing the spatial distribution of these parameters are necessary at precision agriculture. The purpose of this study was to evaluate the feasibility of different methods such as artificial neural networks(ANN) and two geostatistical methods(geographically weighted regression(GWR) and cokriging(CK)) to estimate N, P and K contents. For this purpose, soil samples were taken from topsoil(0–30 cm) at 106 points and analyzed for their chemical and physical parameters. These data were divided into calibration(n = 84) and validation(n = 22). Chemical and physical variables including clay, p H and organic carbon(OC) were used as auxiliary soil variables to estimate the N, P and K contents. Results showed that the ANN model(with coefficient of determination R~2 = 0.922 and root mean square error RMSE = 0.0079%) was more accurate compared to the CK model(with R~2 = 0.612 and RMSE = 0.0094%), and the GWR model(with R~2 = 0.872 and RMSE = 0.0089%) to estimate the N variable. The ANN model estimated the P with the RMSE of 3.630 ppm, which was respectively 28.93% and 20.00% less than the RMSE of 4.680 ppm and 4.357 ppm from the CK and GWR models. The estimated K by CK, GWR and ANN models have the RMSE of 76.794 ppm, 75.790 ppm and 52.484 ppm. Results indicated that the performance of the CK model for estimation of macro nutrients(N, P and K) was slightly lower than the GWR model. Also, the accuracy of the ANN model was higher than CK and GWR models, which proved to be more effective and reliable methods for estimating macro nutrients.  相似文献   

Geologic controls of submarine groundwater discharge: application of remote sensing to north Lebanon     

Amin Shaban  Mohamad Khawlie  Chadi Abdallah  Ghaleb Faour 《Environmental Geology》2005,47(4):512-522

Typical of Mediterranean countries, the Lebanese shoreline is well known for its littoral and offshore groundwater discharges, the so-called submarine springs. The tectonic framework of the terrain explains its interruption by dense geologic structures, i.e., fracturing, faulting, karstic routes, as well as acute dips of rock strata seaward. All of these structures serve as hydrologic agents transporting groundwater to the sea. The study aims to locate these groundwater discharges, and to interpret their geologic controls on land. For this purpose, two major lines of approach were followed. The first is an airborne thermal infrared (TIR) survey using radiometers to identify thermal anomalies, thereby determining the exact location of submarine groundwater discharges (SGDs). The second line of approach is the analysis of satellite images (Landsat 7ETM⁺) to delineate the geologic features that govern the mechanism of water flow, thereby determining their sources on land. Twenty-seven major SGDs were identified, 10 of these being offshore springs, the others littoral springs. The springs show a large variety of discharge configurations and extents, mainly parallel or perpendicular to the shoreline or rounded. Three major structural controls were identified to contribute to the transport of groundwater to the sea. These are karstic galleries, faults, and tilted rock strata, their contributions being 48, 37, and 15%, respectively. The SGDs associated with linear passageways, i.e., karstic galleries and faults, are connected with land aquifer formations several kilometers away from the shoreline. Moreover, the presence of impervious rock formations at many localities along the coastline results in a confined hydrologic system, promoting the flow of SGDs into the sea.  相似文献   

Lead in archaeological samples: an isotopic study by ICP-MS     

A. Mohamad Ghazi   《Applied Geochemistry》1994,9(6)

Inductively coupled plasma mass spectrometry (ICP-MS) has been used to measure the concentration and isotopic composition of Pb in archaeological human and animal skeletal remains, soil from a village site of the Omaha tribe (U.S.A.) and cosmetic pigments.Lead concentrations in human bones from the Omaha tribe vary between 4.8 and 2570 μg/g, with younger people having the highest concentrations. Lead concentrations in animal bones from an Omaha village vary between 0.6 and 3.7 μg/g, and those of three soil samples range between 18 and 21 μg/g. Lead concentrations found in human bones from Anasazi (Utah, U.S.A.) and Alta (Peru) populations vary between 0.7 and 3.2 μg/g.Isotope ratios of a reagent grade Pb(NO₃)₂ solutions were measured by thermal ionization mass spectrometry (TIMS), as well as by ICP-MS to provide laboratory reference materials. The accuracy of the ICP-MS measurements relative to TIMS for the standard solution were found to be within 0.02–0.31% for²⁰⁶Pb/²⁰⁴Pb, 0.02–0.55% for²⁰⁷Pb/²⁰⁴Pb, and 0.16–0.56% for²⁰⁸Pb/²⁰⁴Pb. The precision of measurements on artifacts was 0.42–0.65% for²⁰⁶Pb/²⁰⁴Pb and 0.41–0.62% for²⁰⁷Pb/²⁰⁴Pb, whereas the precision for the same ratios for the bones was 0.85–1.8 and 0.82–1.67%, respectively. For the cosmetic lead-bearing pigments, a precision of 0.07–0.15% was found for both²⁰⁶Pb/²⁰⁴Pb and²⁰⁷Pb/²⁰⁴Pb ratios. Lead isotope ratios of artifacts give a radiogenic Pb signature, of which are close to signatures from PbZn mines of the central U.S. region. Lead isotope ratios of the pigments give non-radiogenic Pb signatures. Lead isotope ratios of the bones differ from those of the artifacts, and although similar in isotopic ratio to the pigments, they are more scattered, suggesting potential mixing of Pb from different regions.  相似文献   

The middle Eocene high-K magmatism in Eastern Iran Magmatic Belt: constraints from U-Pb zircon geochronology and Sr-Nd isotopic ratios     

Siavash Omidianfar  Iman Monsef  Mohamad Rahgoshay  Jianping Zheng  Brian Cousens 《International Geology Review》2020,62(13-14):1751-1768

ABSTRACT

Intrusive rocks are well-exposed in the south Birjand around the Koudakan is herein compared to previously studied outcrops along the middle Eocene to late Oligocene Eastern Iran Magmatic Belt. This pluton is composed mainly of monzonite, quartz-monzonite, and granite with high-K calc-alkaline to shoshonitic affinities. The U-Pb zircon geochronology from monzonite and quartz-monzonite reveals the crystallization ages of 40.96 ± 0.48 to 38.78 ± 0.78 Ma (Bartonian). The monzonite, quartz-monzonite, and granite rocks show similar REEs and trace element patterns, as well as limited variations in εNd_(i) and ⁸⁷Sr/⁸⁶Sr_(i) ratio, suggesting that they are a comagmatic intrusive suite. The chondrite and primitive mantle normalized rare earth and trace element patterns show enrichment in the light rare earth elements, K, Rb, Cs, Pb, Th, and U and depletion in heavy rare earth elements, Nb, Zr, and Ti. The εNd_(i) and ⁸⁷Sr/⁸⁶Sr_(i) values range from +1.32 to +1.68 and 0.7044 to 0.7047, respectively, identical to island-arc basalt composition. The whole-rock Nd model age (T_DM) for the intrusive rocks range between 0.69 and 0.73 Ga. These geochemical and isotopic signatures indicate a subduction-related sub-continental lithospheric mantle source for these rocks. Our new geochemical, isotopic, and geochronological studies integrated with previously published data indicate that the middle Eocene to late Oligocene magmatism in eastern Iran was formed in a post-collisional tectonic environment. We suggest the northeastward subduction of the Neo-Tethys ocean beneath the Lut block and the eastward subduction of the Sistan ocean beneath the Afghan block caused mantle wedge to be metasomatized by slab components. At a later stage, a collision between the Lut and Afghan blocks was accompanied by the lithospheric delamination, and the subsequent asthenospheric upwelling led to the melting of the metasomatized sub-continental lithospheric mantle and the generation of middle Eocene to late Oligocene magmatism in the Eastern Iran Magmatic Belt.  相似文献   

Geological impacts on groundwater pollution: a case study in Khuzestan Province     

Mohamad?SakizadehEmail author  Eisa?Ahmadpour 《Environmental Earth Sciences》2016,75(1):88

The main aims of this study were to examine the sources of pollution with an emphasis on geogenic sources and to predict the groundwater quality with reasonable accuracy. For this purpose, factor analysis/principal component analysis and partial least squares regression were used to analyze a data set of groundwater quality containing 17 parameters measured at 45 different sampling wells in Andimeshk Aquifer during 2006–2013 time period. Factor analysis identified three factors, which were responsible for the data structure explaining 78.3 % of the total variance of the data set. There were various sources of groundwater contamination, based on factor analysis, in which geological formations next to agricultural activities had the most influential effects. Partial least squares regression could predict the quality of groundwater according to the value of water quality index. The amounts of R-squared (0.79) and MSE (0.21) using seven PLS components showed that this method has been successful in the prediction of water quality in the study area.  相似文献