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排序方式: 共有104条查询结果,搜索用时 15 毫秒
81.
Akmal Khodzori Fikri Shahbudin Saad Faiz Mohd Hanapiah Muhammad Hamizan Yusof Muhammad 《Ocean Science Journal》2019,54(3):435-456
Ocean Science Journal - The species lists of scleractinian hard corals in Peninsular Malaysia have not been updated for 15 years. The present study aimed to determine the diversity and abundance... 相似文献
82.
Saad Younes Ghoubachi 《Arabian Journal of Geosciences》2011,5(5):1103-1115
The present work deals with the groundwater aquifer of the Lower Cretaceous sandstone and its sustainable development in Sinai. The studied aquifer system is the most promising groundwater system in Sinai due to its wide extension, hug storage, and good quality. The objective of this paper aims to elucidate the hydrogeological characteristics of the Lower Cretaceous aquifer. The aquifer system occurs under confined conditions. The top surface of the Lower Cretaceous dips steeply towards the southwest direction with step faults. The average sand percent of the penetrated aquifer attains 54%. The main direction of groundwater flow is generally from southwest and locally is concentric to the center of study area related to the influence of the graben block. The aquifer has a hydraulic gradient generally reaches 0.0011 m/m and attains 0.0028 in central portion of study area. The aquifer parameters (effective porosity, transmissivity, and hydraulic conductivity) increase towards the northeast direction with increasing of the sand percentage. Durov diagram plot revealed that the groundwater has been a final stage evolution represented by a NaCl water type. The groundwater salinity increases towards the central of study area coinciding with groundwater flow. The groundwater salinity of the Lower Cretaceous aquifer is brackish water and varies from 2,510 to 5,256 ppm and unsuitable for drinking and domestic purposes. 相似文献
83.
Saad A. Aiban 《Engineering Geology》1995,39(3-4):203-215
The increasing number of construction projects and the lack of good quality soil for use in these projects in eastern Saudi Arabia necessitate the use of available marginal soils. Most, if not all, engineering projects use the fine-grained calcareous sediments, known locally as marl, either as a foundation material or as a fill material. The lack of published information on their engineering characteristics and behavior under ambient conditions has resulted in many construction and post-construction problems. This investigation is one of a series to evaluate the geotechnical properties of selected marl soils obtained from different areas in eastern Saudi Arabia. Marl samples, obtained from Abqaiq, were prepared in the laboratory under controlled conditions and subjected to different tests including CBR (soaked and unsoaked), triaxial compression, unconfined compression and one-dimensional compression tests. Samples were prepared at different moisture contents on both the wet and dry sides of optimum. X-ray diffraction analysis indicates that this marl contains high percentages of dolomite and calcite, in addition to other materials. The molding water content significantly affects the engineering properties of this material. Compaction on the dry side of optimum resulted in samples that have some swelling potential and highly compressible characteristics when subjected to a load after inundation. 相似文献
84.
Major cations and anions were investigated in the Damietta branch of the River Nile. The branch is divided into two different regions; the fresh Nile water (Region A) and the mostly marine environment (Region B). The latter region represents the Damietta estuary. The relative abundance of the major ions in the fresh water system was Na > Ca > Mg > K, HCO3 > Cl > SO4 > CO3, while in the mostly marine area it was Na > Mg > K > Ca, Cl > HCO3 > SO4 > CO3. Regional and monthly variations of the major ions were related to the duration of the Nile discharge and climatic conditions. The major ions -to- chloride ratios for Region A were higher than those in the adjacent Mediterranean waters, while those for the mostly marine region were slightly lower. 相似文献
85.
Using multivariate statistical analyses to evaluate groundwater contamination in the northwestern part of Saudi Arabia 总被引:2,自引:1,他引:1
Taisser Zumlot Awni Batayneh Yousef Nazal Habes Ghrefat Saad Mogren Haider Zaman Eslam Elawadi Abdalaziz Laboun Saleh Qaisy 《Environmental Earth Sciences》2013,70(7):3277-3287
Chemical characteristics of groundwater in the Midyan Basin (northwestern Saudi Arabia) were investigated and evaluated. A total of 72 water samples were collected from existing shallow wells and analyzed for different elements. Two multivariate statistical methods, hierarchical cluster analysis (HCA) and principal components analysis (PCA), were applied to a subgroup of the data set in terms of their usefulness for groundwater classification, and to identify the processes controlling groundwater geochemistry. The subgroup consisted of 46 water samples out of 72 samples and 24 variables included major elements (Ca2+, Na+, Mg2+, K+, Cl?, HCO3 ?, NO3 ?, SO4 2?), minor and trace element (SiO2, Al, As, B, Ba, Cd, Cr, F, Fe, Mo, P, Pb, Sb, Sn, Ti, and V). For water samples, four geochemically distinct clusters (i.e., C1, C2, C3 and C4) have been observed by hierarchical cluster analysis. Cr, F and Pb are the dominant ions in cluster C2. Al, As, Cd, Mo, Sb and Ti are the dominant ions in cluster C3, while B, Ca, Cl, HCO3, K, Mg, Na, SO4 and V are identified as dominant ions in the cluster C4. In the PCA, a total of five components are extracted form the data set, which explained 73.37 % of the total data variability. Among them the first component reveals strong associations between As, B, Cd, Cr, F, Mo, Pb, Sb and Ti. The second component reveals the associations between Ca, Cl, HCO3, Mg, Na, SO4 and V. 相似文献
86.
M.A. Hamdy M.S. Abo Elazm S.M. Saad H.O. Nafie H.E. Abdel Baeth 《Astrophysics and Space Science》2002,279(3):203-218
The aim of this paper is to get new critertia for spectral classification of some early type stars which depend on the flux
in the UV region λ λ 1500–2500 by carrying out spectrophotometric analysis of observational ultraviolet data of stars obtained
by the S2/68 Ultraviolet Sky Survey Telescope (UVSST) aboard the European Space Research Organization (ESRO) Satellite TD1.
We have developed these new criteria based on the Intrinsic Ultraviolet Colour Index (IUI), and the Intrinsic Flux Ratio (IFR).
Using these quantities we are going to represent the results of spectral classification of 323 early type stars mainly from
spectral type B and A. The results of calculations of the Intrinsic Flux Ratios for the stars under investigation together
with their Colour Temperatures (Tc) are given. Comparison between our suggested two new criteria with the MK classification
system and Cucchairo (1980) classification system was carried out.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
87.
Luke R. Chambers Ellery D. Ingall Emily M. Saad Amelia F. Longo Masayuki Takeuchi Yuanzhi Tang Claudia Benitez-Nelson Sheean T. Haley Sonya T. Dyhrman Jay Brandes Aron Stubbins 《Aquatic Geochemistry》2016,22(5-6):555-572
Complexities associated with dissolved organic matter (DOM) isolation from seawater have hampered compositional characterization of this key component of global carbon and nutrient cycles. DOM isolation efficiency by electrodialysis (ED) from salt-containing waters was optimized and evaluated on samples including coastal ocean seawater, open ocean seawater, artificial seawater from axenic cultures of marine phytoplankton, and artificial seawater samples containing standard compounds of different molecular sizes and charge. ED was performed with a system optimized for processing 2–10 L sample volumes. Additionally, the combination of ED and solid-phase extraction, using Bond Elut PPL exchange resin, was evaluated. Using only ED, the following DOC recoveries were achieved: coastal seawater, 71.3 ± 6.5 %; open ocean, 50.5 ± 3.1 %; phytoplankton cultures, 70.3 ± 12.5 %; glucose, 90.2 ± 2.1 %; EDTA, 67.5 ± 9.9 %; and vitamin B12, 98.3 ± 1.6 %. With the combination of PPL and ED techniques, an average DOC recovery of 76.7 ± 2.6 % was obtained for coastal seawater, but this recovery was not statistically different from seawater recoveries using only ED. Comparison of C/N ratios and fluorescence excitation emission matrices taken at the beginning and end of the recovery process for coastal samples processed using only ED indicated that the final recovered material was representative of the DOM present in the original samples. Typical recoveries using combined PPL and ED exceed those of previous isolation methods. 相似文献
88.
89.
Khan Saad van der Meijde Mark van der Werff Harald Shafique Muhammad 《Natural Hazards》2020,103(2):2131-2144
Natural Hazards - Seismic hazard analysis is carried out in this study by estimating ground motion for hypothetical earthquakes in the area of Muzaffarabad, Pakistan, with the MT solution of the... 相似文献
90.
Singh P. R. Saad Farid A. I. Singh A. K. Pant T. K. Aly Ayman A. 《Astrophysics and Space Science》2021,366(5):1-6
We are considering the spacetime described by the metric proposed by Mannheim and Kazanas. The effective potential and the circular orbits are discussed. The rotational velocity derived from the geodesics equation agrees with the observed flat galactic rotation curves. Finally, solutions to the Gordon equation for massless bosons evolving in this spacetime are obtained in terms of Heun general functions.
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