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51.
Hashem A. Madkour Abbas M. Mansour Abu El-Hagag N. Ahmed A. El-Taher 《Arabian Journal of Geosciences》2014,7(9):3427-3440
The textural and geochemical aspects of the sediments of subtropical mangrove ecosystem and surrounding areas have been studied and discussed. Forty sediment samples were collected from different areas of mangrove environment and surrounding areas along the Egyptian Red Sea coast. The sediments of each study areas are characterized by the abundance of sand with minor amounts of mud and gravel. The mean size of the sediments ranged from medium grained to fine grained at the study areas. Cluster analysis showed that the distribution of gravel, sand, and mud fractions is related to bottom facies and type of sediment source. Generally, sand fraction is the main category among the three constituents. Carbonate content recorded minor values in the study areas. The CaCo3 content of the sediments ranged from 4.7 % at Hamata area to 64.9 % at Erier area. Terrigenous and biogenic components are the factor controlling of the carbonate content of studies sediments. The organic carbon content ranged from 1.10 at Hamata area to 3.1 % at Sharm el-Qibli and Erier areas, which is controlled by particle size of the sediments. Phosphorus content in the different studied localities is related to the sources of phosphorus to the area. Our observations provide evidence that there are no significant differences in environmental texture and geochemistry of the sediments of subtropical mangrove ecosystem and surrounding areas of the Egyptian Red Sea coast. 相似文献
52.
El-Sayed Sedek Abu Seif 《Arabian Journal of Geosciences》2014,7(4):1567-1576
Asphaltic roads and constructions in Egypt annually consume a huge amount of aggregates. The physical and geomechanical properties of these aggregates have controlled their performance in which they are used. All road pavements require the efficient use of locally available materials if economically constructed roads are to be built. More than 650 million m3 of fine and coarse aggregates are herein selected to be the tonnage of the present study. The studied Pliocene aggregates have smoothed grading curves and neither a deficiency nor excess of any one particle size, generally produce good mixtures with fewer voids between particles. The litho-particles of coarse aggregates are composed mainly of granites, gneisses, granodiorite, gabbro, and quartz particles. The sand equivalent value of fine aggregates varies from 95 to 97 %. The specific gravity values of the studied aggregates vary from 2.72 to 2.74 gm/cm3 for coarse aggregate and range from 2.51 to 2.54 gm/cm3 for fine aggregate. The Los Angles abrasion value varies from 19 to 24 %. Both coarse and fine aggregates meet the international standards which are suitable for usage as subbase and surface course aggregates, respectively. 相似文献
53.
As the use of mechanical excavation in tunneling and mining activities expands, so has the use of disc cutters in various ground conditions. The impact of moisture content on rock behavior and rock excavation by disc cutters is examined in this study. This was done through a series of full-scale cutting tests using a 292 mm (11.5 in.) disc cutter in a moderate strength sandstone. The muck from the cutting tests was used to determine coarseness index (CI) and absolute size constant (x′). x′ was calculated using Rosin–Rammler distribution (or Weibull) curve, a statistical technique to look at the fragmented rock products. This approach is very popular among the mineral-processing professionals for the evaluation of the particle sizes of the comminution products. x′ and CI show a reasonable correlation with the specific energy of cutting and production rate. Both of these indicators were found to be dependent on the cut spacing and the interaction between the adjacent cuts, as anticipated. This paper explains the background information on this topic, reviews the laboratory testing, and offers analysis of the results of grain size distribution and its relationship with specific energy and cutting geometry. It should be noted that the experimental program was limited to only one rock type and additional testing on the other rock types is required to expand the results of the current study. 相似文献
54.
The propagation and the head—on collision of nonlinear dust—acoustic solitary waves (DASWs) in dusty plasmas consisting of
electrons, ions and negative as well as positive dust particles are investigated. Applying an extended Poincaré-Lighthill-Kuo
(PLK) method, Kortwege-de Vries equations and analytical phase shifts after the head-on collision of two DASWs in dusty plasmas
are obtained. Analytically and numerically, the relevance of the phase shifts and trajectories to the positive-to-negative
dust number density ratio, the ratio of the ion number density to negative dust number density, negative-to-positive dust
particle mass ratio, and the ion-to-electron temperature ratio effects is explicitly demonstrated. Moreover, the current findings
are applied to different regions of space, viz. cometary tails, mesosphere, Jupiter’s magnetosphere. 相似文献
55.
In Malaysia, the endemic level of dengue fever (DF) has already changed morbidity indicators, and the magnitude of these incidences in the last few years has surpassed the incidences of all other diseases of compulsory notification. The reasons for the dramatic emergence of DF are complex and not well understood. There are many factors that contribute to the epidemiological conditions that favour viral transmission by the main mosquito vector. This study, therefore, is filling this gap by analysing the impact of dengue incidence at a local (Subang Jaya) scale using environmental factors. Meteorological data and land-use pattern were consolidated using geographic information system (GIS) and its components as an analytical tool. We have shown that weather variables (relative humidity, temperature and precipitation) have significant correlation with DF incidence with seasonal variation. Besides land-use pattern, DF incidence shows the higher distribution in the residential area, followed by commercial and industrial area. This is due to the higher population density in residential area as well as favourable places for the breeding of dengue-carrying Aedes mosquitos created by humans in the residential area, especially one-storey houses. The analysis on the trends of DF incidence towards various housing types indicate that most of the victims’ houses fall into interconnection houses and mixed houses types compared to the independent houses area. The outcome driven from this analysis suggested that each character of the environmental factors has their own risk towards dengue incidence. In line with that, it is possible to develop a dynamic model of DF transmission using the knowledge produced by this comprehensive time series data and the results provided by the different analyses. 相似文献
56.
Salem S. Abu Amr Hamidi Abdul Aziz Mohd Nordin Adlan Shuokr Qarani Aziz 《洁净——土壤、空气、水》2013,41(2):148-152
This study investigated the effects of O3 and O3/H2O2/Fe2+ in the advanced oxidation processes (AOPs) on the biodegradable and soluble characteristics of semi‐aerobic stabilized solid waste leachate. The biodegradability (BOD5/chemical oxygen demand, COD) ratio improved from 0.034 to 0.05 and 0.1 following O3 and O3/H2O2/Fe2+, respectively. Fractions of biodegradable COD(bi) (24%), non‐biodegradable COD(ubi) (76%), soluble COD(s) (59%), biodegradable soluble COD(bsi) (38%), non‐biodegradable soluble COD(ubsi) (62%), and particulate COD (PCOD) (41%) in stabilized leachate were also investigated. The fraction of COD(bi) increased to 28 and 36% after applying O3 and O3/AOPs, respectively. COD(S) increased to 59% after O3 and to 72% after O3/AOPs, whereas COD(bsi) increased to 38 and 51% after O3 and O3/AOPs, respectively. The removal efficiency of COD(S) was obtained at 5% after O3 alone and improved to 51% following ozone‐based AOPs, whereas the removal efficiency of PCOD improved from 25% after O3 to 71% after ozone‐based AOPs. 相似文献
57.
Osama Elsayed Ahmed Attia Ahmed M. Abu Khadra Ahmed H. Nawwar Gamal E. Radwan 《Arabian Journal of Geosciences》2012,5(3):481-499
In Mabahiss Bay, north Hurghada City, Red Sea, Egypt, the bathymetric measurements show the irregular topography of the bottom. The bottom sediments are mainly composed of sand fractions (average 73.5%). Gravel and sand contents decrease with depth. On the other hand, silt and clay percents show indirect relation with depth. Abnormally, there are some spots found near the coast where the percent of both silt and clay increases. They also show carbonate sediments (average 90.15%) increasing toward the bay center. The narrow belt adjacent to the shore area has lower carbonate content reflecting the effect of clastic sediments input into the area. The sediments in the study area have more than one source as indicated from the results of the mechanical analysis. Wide range of grain size distributions, clay spots and low carbonate content near the shore indicate change in the nature of sedimentary environment (i.e., pollution) which may be caused by land filling accompanied with urbanization and building of touristic resorts and centers. The organic matter content in the sediments is much higher than that of the other areas in the Red sea (average 4.8%) with considerable accumulation in the inner most parts of the bay. This may be due to relative abundance of organic productivity, direct discharge of domestic waste in some spots along the coast of the study area, and/or local contamination of hydrocarbons (i.e., tar balls thrown out on shore by weak waves through the few inlets of the study area). The average concentrations of lead, nickel, copper, and cadmium are 44, 34, 51, and 3.1?ppm, respectively. The suggested origin of these metals is either organic (localized oil pollution), or using of antifouling and anticorrosive paints from fishing and tourist boats. Other metals, particularly manganese (average 77?ppm), cobalt (average 51?ppm), and zinc (average 16?ppm) as well as sodium (average 0.32%) and potassium (av. 0.10%) show a common trend of increasing concentration toward the outermost parts of the bay. Some parts along shoreline have increasing concentrations, even if these parameters having a common trend of increase towards the center of the bay. This may be either due to sewage and wastewaters discharges from many outlets of tourist centers and fishermen and cargo boats, and/or terrestrial sediments input. Direct comparison of the present levels of heavy metals in Mabahiss Bay with other published data along the Red Sea and Gulf of Suez shows that the study area has higher concentrations. Dredging, land filling, localized oil pollution, using of antifouling and anticorrosive paints from fishing and tourist boats (where the bay is used as harbor for many of fishermen and cargo boats), sewage, variable amounts of municipal wastewater from many outlets of tourist centers considered to be the sources of pollution within Mabahiss bay. There are many effects of pollution on Mabahiss Bay environment among which: (1) death of fishes, seaweeds, birds, marine mammals, etc., (2) damage of beaches and other recreational areas, (3) damage of marine ecosystem by eliminating or decreasing population of certain species, (4) hazard to human from ingesting contaminated food, and more. 相似文献
58.
Hisham?A.?GahlanEmail author Shoji?Arai Fawzy?F.?Abu El-Ela Akihiro?Tamura 《Contributions to Mineralogy and Petrology》2012,163(2):225-241
Ultramafic cumulates, mainly crustal true wehrlites, were discovered and described in the mantle–crust transition zone (MTZ)
and the extremely lower layered gabbro sequence of the Ras Salatit ophiolite, Central Eastern Desert, Egypt. They form either
boudinaged lensoidal tabular bodies or interdigitated layers often concordant with the planolinear fabrics of the Ras Salatit
ophiolite rocks. The contact between wehrlites and the host MTZ dunite or layered gabbro is razor sharp, lobate and/or sinuous,
without chilled margins or any visible deformations. The Ras Salatit wehrlites are orthopyroxene-free and composed mainly
of olivine and clinopyroxene. They are texturally equilibrated and show a characteristic poikilitic texture. Crystallization
order of the Ras Salatit wehrlites is olivine/spinel followed by clinopyroxene with the absence of plagioclase. Olivine and
clinopyroxene of the Ras Salatit wehrlites are compositionally uniform and conspicuously high in Mg#, mostly around 0.93 and
0.92, respectively. Moreover, the clinopyroxene shows low Ti and Al contents coupled with marked depletion in LILE. The calculated
melt in equilibrium with clinopyroxene from the Ras Salatit wehrlites is largely similar to lavas from the Izu-Bonin forearc.
Given the above characteristics, the Ras Salatit wehrlites were produced by crystal accumulation from a hydrous depleted basaltic/tholeiitic
melt corresponding to temperatures between 1,000 and 1,100°C at the oceanic crustal pressure (~2 kbar). The involved hydrous
tholeiitic melt has been probably formed by fluid-assisted partial melting of a refractory mantle source (similar to the underlying
harzburgites) in a somewhat shallow sub-arc environment. 相似文献
59.
Numerous time-consuming equations, based on the relationship between the reliability and representativeness of the data utilized in defining variables and constants, require complex parameters to estimate bedload transport. In this study the easily accessible data including flow discharge, water depth, water surface slope, and surface grain diameter (ds0) from small rivers in Malaysia were used to estimate bedload transport. Genetic programming (GP) and artificial neural network (ANN) models are applied as complementary tools to estimate bed load transport based on a balance between simplicity and accuracy in small rivers. The developed models demonstrate higher performance with an overall accuracy of 97% and 93% for ANN and GP, respectively compared with other traditional methods and empirical equations. 相似文献
60.
Muhammad Malik Nauman Murtuza Mehdi Asif Iqbal Muhammad Saifullah Abu Bakar Brahim Aissa Dk Nur Afiqah Jalwati Puteri Amer Farhan Rafique 《地下水科学与工程》2019,(4):373-382
In many circumstances involving heat and mass transfer issues,it is considered impractical to measure the input flux and the resulting state distribution in the domain.Therefore,the need to develop techniques to provide solutions for such problems and estimate the inverse mass flux becomes imperative.Adaptive state estimator(ASE)is increasingly becoming a popular inverse estimation technique which resolves inverse problems by incorporating the semi-Markovian concept into a Bayesian estimation technique,thereby developing an inverse input and state estimator consisting of a bank of parallel adaptively weighted Kalman filters.The ASE is particularly designed for a system that encompasses independent unknowns and/or random switching of input and measurement biases.The present study describes the scheme to estimate the groundwater input contaminant flux and its transient distribution in a conjectural two-dimensional aquifer by means of ASE,which in particular is because of its unique ability to efficiently handle the process noise giving an estimation of keeping the relative error range within 10%in 2-dimensional problems.Numerical simulation results show that the proposed estimator presents decent estimation performance for both smoothly and abruptly varying input flux scenarios.Results also show that ASE enjoys a better estimation performance than its competitor,Recursive Least Square Estimator(RLSE)due to its larger error tolerance in greater process noise regimes.ASE's inherent deficiency of being slower than the RLSE,resulting from the complexity of algorithm,was also noticed.The chosen input scenarios are tested to calculate the effect of input area and both estimators show improved results with an increase in input flux area especially as sensors are moved closer to the assumed input location. 相似文献