Gravitational instability of a non-linear magnetic fluid     

A. A. Abdullah 《Astrophysics and Space Science》1993,204(2):289-295

The problem of gravitational instability of an infinite homogenous fluid has been considered in the presence of a non-vertical magnetic field. A non-linear relation between the magnetic field and the magnetic induction proposed by P.H. Roberts (1981) in the context of neutron stars has been used. The dispersion relations have been obtained. It has been found that Jeans's criterion for instability is unaffected by this non-linear relationship even if the effect due to rotation is considered in the presence of a non-vertical magnetic field.  相似文献   

The importance of environmental science     

Abdullah R. Al-Kandari 《GeoJournal》1994,33(4):341-348

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Earthquake risk assessment in NE India using deep learning and geospatial analysis     

Ratiranjan Jena  Biswajeet Pradhan  Sambit Prasanajit Naik  Abdullah M. Alamri 《地学前缘(英文版)》2021,12(3):101110

Earthquake prediction is currently the most crucial task required for the probability, hazard, risk mapping, and mitigation purposes. Earthquake prediction attracts the researchers' attention from both academia and industries. Traditionally, the risk assessment approaches have used various traditional and machine learning models. However, deep learning techniques have been rarely tested for earthquake probability mapping. Therefore, this study develops a convolutional neural network (CNN) model for earthquake probability assessment in NE India. Then conducts vulnerability using analytical hierarchy process (AHP), Venn's intersection theory for hazard, and integrated model for risk mapping. A prediction of classification task was performed in which the model predicts magnitudes more than 4 Mw that considers nine indicators. Prediction classification results and intensity variation were then used for probability and hazard mapping, respectively. Finally, earthquake risk map was produced by multiplying hazard, vulnerability, and coping capacity. The vulnerability was prepared by using six vulnerable factors, and the coping capacity was estimated by using the number of hospitals and associated variables, including budget available for disaster management. The CNN model for a probability distribution is a robust technique that provides good accuracy. Results show that CNN is superior to the other algorithms, which completed the classification prediction task with an accuracy of 0.94, precision of 0.98, recall of 0.85, and F1 score of 0.91. These indicators were used for probability mapping, and the total area of hazard (21,412.94 km²), vulnerability (480.98 km²), and risk (34,586.10 km²) was estimated.  相似文献   

Incorporation of silica into the goethite structure: a microscopic and spectroscopic study     

Abdullah Musa Ali  Eswaran Padmanabhan  Hassan Baioumy 《中国地球化学学报》2018,37(6):911-921

Quartz and iron (hydr)oxide are reactive surface phases that are often associated with one another in soils and sediments. Despite the several studies on the coating of quartz with iron oxides, the reactivity of dissolved species (Si) leached from quartz with iron (hydr)oxides has received limited attention. In this study, goethite synthesized on quartz substrates were characterized using field emission scanning electron microscopy, X-ray diffraction (XRD), transmission electron microscopy, and Fourier-transform infrared (FT-IR) spectroscopy. The SEM characterization revealed that bundles of thin parallel aligned goethite rods were formed at pH?>?10, while large pseudohexagonal crystals of twinned goethite needles were synthesized at pH?≤?10 after dehydration and hydration in the alkaline media. TEM analysis showed expanded and distorted lattice spacing of the crystal structure of iron (hydr)oxide due to silica incorporation. The characterization showed that silica increased the crystallite size of the goethite and transformed its acicular texture to a larger, twinned needle structure. FT-IR and XRD analyses revealed band shifts in crystal bonds as well as new bond formations, which indicate the presence of changes in the chemical environment of Fe–O and Si–O bonds. Thus, the presence of sorbed silicates modifies the crystal and lattice structure of goethite.  相似文献   

Geochemical variation of the groundwater characters along Wadi Qudaid,northeast Jeddah,westcentral Arabian Shield,Saudi Arabia     

Mohamed A. Sharaf  Abdullah R. Sonbul  Ali A. Mesaed 《Arabian Journal of Geosciences》2018,11(16):470

Wadi Qudaid is present about 120 km northeast of Jeddah, Saudi Arabia. The area includes Precambrian Arabian Shield, Tertiary sedimentary rocks, Tertiary basic volcanics (harrat), and finally Quaternary wadi deposits which represent the main aquifer of Wadi Qudaid area. The present study indicates the presence of pronounced geochemical variations in the groundwater characters along the main channel of Wadi Qudaid from the southwestern part (downstream) to the northeastern (upstream) part. The groundwater-bearing horizon is thicker in the downstream part than the upstream part. The study also revealed that the groundwater is of good quality in the upstream (NE) part than the downstream (SW) part. This is related to the addition and depletion of many elements during the groundwater trip from NE to SW and the addition and depletion of some elements. The downstream part is of high hardness and TDS when compared with the upstream part. Also, the downstream part is of high bisnous element (As, Co, Ni) than the upstream part. The groundwater of the southwestern part of Wadi Qudaid are free from the following elements: i.e., Al, Mn, Fe, Ni, Cu, Zn, and Pb.  相似文献   

Groundwater potential mapping by combining fuzzy-analytic hierarchy process and GIS in Beyşehir Lake Basin,Turkey     

Erhan Şener  Şehnaz Şener  Ayşen Davraz 《Arabian Journal of Geosciences》2018,11(8):187

Delineation of the groundwater potential zones is one of the most essential process for the sustainable management of the groundwater sources. However, groundwater studies are quite hard and complex for many regions besides consuming time and cost. This study focused on the groundwater potential mapping in Bey?ehir Lake Basin. Mainly, fuzzy-analytic hierarchy process (fuzzy-AHP) integrated with GIS was used to determine potential zones for groundwater. Seven parameters, namely lithology, lineament, drainage density, land use, slope, soil type, and rainfall were evaluated and Groundwater Potential Index (GWPI) was calculated using weight and rating coefficients of each parameter. According to obtained results, GWPI varies from 0.07665 to 0.28243 in the basin. The low, moderate, and high groundwater potential classes were determined with quantile classification method. The groundwater potential map demonstrates that the high groundwater potential area is located around the lake shore, in the alluvium and limestone fields because high permeability rates depend on soil type, low slope, karstic structure, and agricultural activities in these regions. In addition, the distribution of the springs confirms with groundwater potential area determined with this study.  相似文献   

Performance evaluation of Turkish disaster relief management system in 1999 earthquakes using data envelopment analysis     

Üstün  Abdullah Korkut  Barbarosoğlu  Gülay 《Natural Hazards》2015,75(2):1977-1996

Natural Hazards - This study estimates the relative efficiency of disaster relief organizations that participated in the relief activities following the Marmara and Düzce earthquakes that took...  相似文献   

Application of Multi-Criteria Decision Analysis to Geoelectric and Geologic Parameters for Spatial Prediction of Groundwater Resources Potential and Aquifer Evaluation     

K. A. N. Adiat  M. N. M. Nawawi  K. Abdullah 《Pure and Applied Geophysics》2013,170(3):453-471

Prediction of groundwater resources potential is a spatial decision problem that involves a set of multiple evaluation parameters. In order to produce a groundwater resources potential prediction model of higher reliability and precision in a given study area, the effects of all the important parameters that can contribute to the groundwater occurrence in the area must be integrated. However, the methodology of integrating these parameters such that the relative importance of each is reflected is still a challenge that has not been efficiently handled. In this study, the principle of multi-criteria decision analysis in the context of the analytical hierarchy process is proposed as a technique that can yield a prediction model of higher reliability and precision. The proposed technique was applied to geoelectric and geologic parameters, derived from the results of the interpretation of 2D resistivity imaging data acquired from the study area. The advantage of the proposed technique is that it reduces bias in decision making. The main objective of the study is to produce groundwater potential map for the area. Furthermore, an attempt was also made in the study to characterize the aquifer of the area by estimating the Dar-Zarrouk parameters, using the integration of borehole and 2D resistivity data. The success rate (accuracy) of the prediction was established to be 80 %. Furthermore, the regression line fitted to the aquifer transmissivity and transverse resistance data shows linear relationship with a high regression coefficient of 0.79. The prediction success rate obtained showed that the method proposed in this study is reliable, accurate, and an improved technique of integrating multiple parameters for holistic evaluation of groundwater resources.  相似文献   

Exploring the association between the occurrence of earthquakes and the geologic-tectonic variables in the Red Sea using logistic regression and GIS     

Khalid Al-Ahmadi  Sharaf Al-Ahmadi  Abdullah Al-Amri 《Arabian Journal of Geosciences》2014,7(9):3871-3879

Al-Ahmadi et al. (Arab J Geosci doi:10.1007/s12517-013-0974-6, 2013) applied spatial pattern analysis techniques to a seismic data catalogue of earthquakes beneath the Red Sea in order to explore and detect global and local spatial patterns in the occurrence of earthquakes over the years from 1900 to 2009 using a geographical information system (GIS). They found that the techniques of spatial pattern analysis that they applied could detect global and local clusters and broader spatial patterns in the occurrence of earthquakes and concluded that earthquakes with higher magnitudes were notably concentrated beneath the central and southern areas of the Red Sea, while earthquakes with low and moderate magnitudes were concentrated beneath the northern area of the Red Sea. The aim of this paper is to report on the application of logistic regression models to explore the associations between the likelihood of the occurrence of an earthquake beneath the Red Sea and four selected variables, namely: (1) proximity to the boundary of the African–Arabian plates, (2) proximity to transform faults, (3) proximity to the mid-Red Sea ridge and (4) the stage of rift evolution. The study was undertaken to evaluate the potential of logistic regression modelling for research exploring potential associations between earthquakes and geological and tectonic variables. The results revealed that none of the assumptions underpinning the logistic regression models had been violated for the three logistic regression models that were used in this research. The authors inferred that the occurrence of the earthquakes beneath the Red Sea was statistically significantly associated with the proximity to the African–Arabian plate boundary. We concluded that earthquakes of moderate magnitudes occurred in the zone which represents the late evolutionary stage of the Red Sea rift, including the transition zone beneath the central area and the late-stage continental rift zone beneath the northern area of the Red Sea. In contrast, earthquakes with high magnitudes tended to occur in close proximity to the mid-ridges of the Red Sea.  相似文献   

Utilization of supervised classification in structural and lithological mapping of Wadi Al-Marwah Area,NW Arabian Shield,Saudi Arabia   总被引：1，自引：0，他引：1  

Adel Zein Bishta  Abdullah Rasheed Sonbul  Wuadee Kashghari 《Arabian Journal of Geosciences》2014,7(9):3855-3869

Wadi Al-Marwah area is located in the northwestern part of the Arabian Shield, Saudi Arabia. It is mainly covered by Precambrian igneous and sedimentary rock units. This area was not subjected to previous detailed lithological or structural mapping. This study aims to apply supervised classification technique of remotely sensed digital satellite data of Landsat 7 for detailed lithological and structural mapping of the area. The fusion between multispectral Enhanced Thematic Mapper (ETM)+ data and high-resolution panchromatic ETM+ band-8 produced a color composite fused image for the study area, scale 1:50,000. The structural lineaments of the study area were extracted and interpreted from the digital imageries data. Little discrepancies or improvements were detected when combining the supervised classification results with the Landsat ratios or principal component analysis. These highlighted the benefits of multispectral classification, especially in terms of lithologic discrimination. The overall results of image processing techniques, applied in this work, were excellent and succeeded in the performance of a more detailed and accurate lithological and structural maps (scale 1:50,000) than the previous published maps for the investigated area.  相似文献