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Maher Omar Abdallah Shanableh Adnan Basma Samer Barakat 《Geotechnical and Geological Engineering》2003,21(3):283-295
Most of the topsoils encountered in United Arab Emirates and in the Arabian Peninsula are granular soils with small percentages
of silt and clay. Determination of the compaction characteristics of such soils is an essential task in preparing for construction
work. The accumulating experience over many years of soil testing in our laboratories suggested that there exists an underlying
trend that governs the compaction characteristics of such soils. As such, a study was undertaken to assess the compaction
characteristics of such soils and to develop the governing predictive equations. For the purposes of this study, 311 soil
samples were collected from various locations in the United Arab Emirates, and tested for various including grain-size distribution,
liquid limit, plasticity index, specific gravity of soil solids, maximum dry density of compaction, and optimum moisture content
following ASTM D 1557-91 standard procedure C. Following the development of the predictive equations, a new set of 43 soil
samples were collected and their compaction results were used to test the validity of predictive model. The range of variables
for these soils were as follows: percent retained on US sieve #4 (R#4): 0–68; Percent passing US sieve #200 (P#200): 1–26;
Liquid limit: 0–56; Plasticity index: 0–28; Specific gravity of soil solids: 2.55–2.8.
Based on the compaction tests results, multiple regression analyses were conducted to develop mathematical models and nomographic
solutions to predict the compaction properties of soils. The results indicated that the nomographs could predict well the
maximum dry density within ±5% confidence interval and the optimum moisture content within ±3%.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
23.
Non-Maxwellian ion velocity distribution functions have been theoretically predicted and confirmed by observations, to occur at high latitudes. These distributions deviate from Maxwellian due to the combined effect of the E×B drift and ion-neutral collisions. The majority of previous literature, in which the effect of ion self-collisions was neglected, established a clear picture for the ion distribution under a wide range of conditions. At high altitudes and/or for solar maximum conditions, the ion-to-neutral density ratio increases and, hence, the role of ion self-collisions becomes appreciable. A Monte Carlo simulation was used to investigate the behavior of O+ ions that are E×B-drifting through a background of neutral O, with the effect of O+ (Coulomb) self-collisions included. Wide ranges of the ion-to-neutral density ratio n i /n n and the electrostatic field E were considered in order to investigate the change of ion behavior with solar cycle and with altitude. For low altitudes and/or solar minimum (n i /n n \leq10?5), the effect of self-collisions is negligible. For higher values of n i /n n , the effect of self-collisions becomes significant and, hence, the non-Maxwellian features of the O+ distribution are reduced. For example, the parallel temperature T i\Vert increases, the perpendicular temperature T i⊥ decreases, the temperature anisotropy approaches unity and the toroidal features of the ion distribution function become less pronounced. Also, as E increases, the ion-neutral collision rate increases, while the ion-ion collision rate decreases. Therefore, the effect of ion self-collisions is reduced. Finally, the Monte Carlo results were compared to those that used simplified collision models in order to assess their validity. In general, the simple collision models tend to be more accurate for low E and for high n i /n n . 相似文献
24.
Mohamed El Mourabet Ahmed Barakat Mohamed Najib Zaghloul Mohamed El Baghdadi 《Arabian Journal of Geosciences》2018,11(6):126
This study focuses on the Lower-Middle Miocene syn-orogenic flysch deposits of the Zoumi basin to infer source area paleoclimatic conditions, the intensity of source rocks paleoweathering, and mechanical sorting and recycling effects. The mudrocks are enriched in Al2O3, Fe2O3, CaO, and TiO2 relative to PAAS and depleted in the other mobile major elements. There are high positive correlations between SiO2, Al2O3, and TiO2 and negative correlations between SiO2 and CaO. Geochemically, the mudstones are mainly classified as shales, Fe-shales, and wackes. Various discriminant diagrams were used to reveal the inferred tectonics, source paleoweathering intensity, and paleoclimatic conditions. Chemical index of alteration (CIA) and chemical index of weathering (CIW) values for Lower-Middle Miocene vary from 50 to 80% indicating low to moderate degree of source area weathering compatible with non-steady-state weathering under wet and humid paleoclimatic conditions. Locally (Zoumi mid-section) CIA values are higher (>?80) reflecting intense source area weathering, which may be attributed to high tectonic impulses and more humid conditions during deposition. The combination of ICV-CIA, Al2O3-Zr-TiO2, and Th/Sc-Zr/Sc values suggests the bulk rock is chemically immature and has experienced modest physical sorting and recycling reflecting little transportation until the final deposition. 相似文献
25.
Molecular geochemical properties of crude oils and surface petroleum seeps from the southern part of the Gulf of Suez were evaluated. The characterizations of individual aliphatic, aromatic, and biomarker compounds were based on gas chromatography (GC) and gas chromatography/mass spectrometry (GC/MS) analyses. The results provided strong evidence for a close genetic association of these samples. The geochemical characteristics suggest an origin from Tertiary source rocks deposited in a normal marine environment that received continental runoff. The molecular signatures of the investigated samples were very similar to those of the Lower Miocene Rudeis Formation source rock in the southern Gulf of Suez. Further, biomarker fingerprints of the investigated oil seeps were compared with those of the Dead Sea asphalt, as well as the bitumen from some Egyptian mummies reported in the literature. The results demonstrate that oil seeps from the southern end of Gebel El Zeit were used by ancient Egyptians for embalming. © 2005 Wiley Periodicals, Inc. 相似文献
26.
Mohamed Barakat A. Gibril Suzana A. Bakar Kouame Yao Mohammed Oludare Idrees 《国际地球制图》2017,32(7):735-748
In this study, we investigated the performance of different fusion and classification techniques for land cover mapping in Hilir Perak, Peninsula Malaysia using RADAR and Landsat-8 images in a predominantly agricultural area. The fusion methods used are Brovey Transform, Wavelet Transform, Ehlers and Layer Stacking and their results classified into seven different land cover classes which include (1) pixel-based classifiers (spectral angle mapper (SAM), maximum likelihood (ML), support vector machine (SVM)) and (2) Object-based (rule-based and standard nearest neighbour (NN)) classifiers. The result shows that pixel-based classification achieved maximum accuracy of the optical data classification using SVM in Landsat-8 with 74.96% accuracy compared to SAM and ML. For multisource data classification, the highest overall accuracy recorded for layer stacking (SVM) was 79.78%, Ehlers fusion (SVM) with 45.57%, Brovey fusion (SVM) with 63.70% and Wavelet fusion (SVM) 61.16%. And for object-based classifiers, the overall classification accuracy is 95.35% for rule-based and 76.33% for NN classifier, respectively. Based on the analysis of their performances, object-based and the rule-based classifiers produced the best classification accuracy from the fused images. 相似文献
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Mohamed El Mourabet Ahmed Barakat Jamila Rais Mohamed Najib Zaghloul Achraf Atouabat 《Arabian Journal of Geosciences》2018,11(9):209
The Zoumi Basin was generated in a collisional tectonic setting during the Lower-Middle Miocene. The syn-orogenic flysch deposits of the basin have been well investigated by petrographic and geochemical studies to characterize the composition, source to sink routing system, and tectonic setting of the Zoumi flysch. Forty-three sandstone samples and 45 mudstone samples have been gathered from six measured stratigraphic sections. These samples have been analyzed using XRD, XRF, inductively coupled plasma-mass spectrometry (ICP-MS) for mudrocks and petrographic investigation for sandstones. The Lower-Middle Miocene Zoumi flysch is defined as sublitharenites and quartzarenites according to mineralogical content. Detrital grains are commonly subangular to subrounded, poorly sorted, and rich in quartz grains. Point counting modal analysis leads to craton interior and recycled orogen provenance with significant first-cycle sediment supply and low sedimentary recycling. Several chemical ratios (Al2O3/TiO2, La/Th, Cr/Th, Th/Sc, Zr/Sc) as well as chondrite-normalized REE patterns with flat HREE, LREE enrichment, and negative Eu anomaly suggest a dominant felsic rock sources. However, V-Ni-La*4, V-Ni-Th*10, and Th/Sc vs. Cr/Th plots do not exclude a mafic supply source nature which is evidenced by numerous ophiolitic outcrops scattered throughout the Mesorifan Subdomain (Mesorifan Ophiolitic Suture Zone). 相似文献
29.
The energization of charged particles, due to interaction with the ambient electromagnetic turbulence, has a significant influence
on the plasma transport in space. The effect of wave-particle interactions on the outflow characteristics of polar wind plasma
was investigated. The theoretical model included gravitational acceleration (g), polarization electrostatic field (Ep), and divergence of the geomagnetic field. Within the simulation region (1.7 to 10
earth radii, Re) the ions were assume to be collisionless and the electrons to obey a Boltzmann relation. Profiles of altitude-dependent
diffusion coefficients [D⊥ (O+) and D⊥ (H+)] were computed from the wave spectral density (S) observed by the Plasma Wave
Instrument (PWI) on board DE-1. The effects of WPI were introduced via a Monte Carlo technique, and an iterative approach
was used in order to converge to self-consistent results. The main conclusions of this study were the following. As a result
of perpendicular heating, the temperature anisotropy (T| /T⊥) was reduced and even reversed (T| < T⊥) at high altitudes. The
O+ velocity distribution function developed a conic shape at high altitudes. The altitudes above which the WPI influences
the O+ ions were lower than those for the H+ ions. The escape flux of O+ could be enhanced by more than an order of magnitude
while the H+ flux remains constant. The O+ ions are heated more efficiently than the H+ ions, especially at low altitudes
due to the 'pressure cooker' effect. As the ions are heated and move to higher altitudes, the ion's Larmor radius a
L
may become comparable to the perpendicular wavelength λ⊥. As the ratio aL /λ⊥ becomes > 1, the heating rate becomes self-limited
and the ion distribution displays toroidal features. This result is consistent with the observation of O+ toroidal distribution
in the high altitude ionosphere. Finally, the large variability in the wave spectral density S was studied. This variability
was found to change our results only in a quantitative manner, while our conclusions remained qualitatively unchanged.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
30.
Solutions are derived for the potential distributions over one-layer and two-layer random conductivity earth models for the direct current resistivity method. Monopole and Wenner arrays are considered. It is shown that the random potential due to a spatially stationary Gaussian random conductivity is also Gaussian but not spatially stationary. The ensemble and sample statistics of the random kernel and apparent resistivity are examined. Representative curves of these functions are presented to show the effects of a random conductivity profile on them. It is shown that the effect of the random nature of the conductivity profile on an apparent resistivity sounding curve is greatest for small electrode spacings. 相似文献