Radiation transfer for linearly anisotropic phase functions     

M. S. Abdel Krim 《Astrophysics and Space Science》1990,164(1):69-77

Radiative transfer equation in a plane-parallel medium with isotropic boundary conditions for linearly anisotropic scattering phase function is considered. Two coupled integral equations for total density of radiation and total radiation flux are obtained. The Galerkin method is used to solve these equations. Numerical results for the radiative fluxes at the boundaries show that the Galerkin method yields accurate results compared well with other exact methods.  相似文献   

Ground motion spatial variability effects on seismic response control of cable-stayed bridges     

Shehata E. Abdel Raheem  Toshiro Hayashikawa  Uwe Dorka 《地震工程与工程振动(英文版)》2011,10(1):37-49

The spatial variability of input ground motion at supporting foundations plays a key role in the structural response of cable-stayed bridges (CSBs); therefore, spatial variation effects should be included in the analysis and design of effective vibration control systems. The control of CSBs represents a challenging and unique problem, with many complexities in modeling, control design and implementation, since the control system should be designed not only to mitigate the dynamic component of the structural response but also to counteract the effects of the pseudo-static component of the response. The spatial variability effects on the feasibility and efficiency of seismic control systems for the vibration control of CSBs are investigated in this paper. The assumption of uniform earthquake motion along the entire bridge may result in quantitative and qualitative differences in seismic response as compared with those produced by uniform motion at all supports. A systematic comparison of passive and active system performance in reducing the structural responses is performed, focusing on the effect of the spatially varying earthquake ground motion on the seismic response of a benchmark CSB model with different control strategies, and demonstrates the importance of accounting for the spatial variability of excitations.  相似文献   

Recharge and contamination sources of shallow and deep groundwater of pleistocene aquifer in El-Sadat industrial city: isotope and hydrochemical approaches     

M. A. Ahmed  S. G. Abdel Samie  H. M. El-Maghrabi 《Environmental Earth Sciences》2011,62(4):751-768

Hydrochemical and isotopic researches were conducted in El-Sadat City groundwater system to identify groundwater alteration, recharge, residence time and extent of pollution. The groundwater salinity gradually increases as the groundwater moves from northeastern to southwestern parts of the city. Groundwater generally shows mineralization decreasing with depth, indicating that the possibility of recent water penetration far below the surface is limited. Shallow groundwater has an elevated level of nitrate, which is attributed to anthropogenic sources due to intensive agricultural activity. The limit of high nitrate water may mark the maximum penetration of groundwater from the surface, which is found in depths <100 m. The northeastern and southwestern industrial areas are highly contaminated by some heavy metals, which may originate from some local industrial effluents. The sewage oxidation ponds seem to show no effect on groundwater; hence, these ponds are not a point source for these heavy metals. Dissolved ions depict five different hydrochemical facies, and stable isotopes define the recharge mechanisms, the origin of groundwater and the hydraulic confinement of deep groundwater. The deep groundwater is untritiated and has long residence times (in the order of thousands of years). Three different hydrochemical groups have been recognized and mapped in El-Sadat City, based on the chemical and isotopic information of the groundwater. These groups have different levels of contamination. The deep groundwater samples are significantly less impacted by surface activities and it appears that these important water resources have very low recharge rates and would, therefore, be severely impacted by overabstraction. The extensive exploitation of groundwater for drinking water supply would shortly be reflected by a gradual decline of the groundwater table in El-Sadat City. Amelioration of groundwater quality requires further management strategies and efforts in the forthcoming years.  相似文献   

Conceptual model and numerical simulation of the hydrothermal system in Hammam Faraun hot spring, Sinai Peninsula, Egypt     

Mohamed Abdel Zaher  Sachio Ehara  Gad El-Qady 《Arabian Journal of Geosciences》2011,4(1-2):161-170

The tectonic position of Egypt in the northeastern corner of the African continent suggests that it may possess significant geothermal resources, especially along its eastern margin. The most of the thermal springs in Egypt are located along the shores of Gulf of Suez and Red Sea. These springs are probably tectonic or nonvolcanic origin associated with the opening of the Red Sea—Gulf of Suez rifts, where the eastern shore of the Gulf of Suez is characterized by superficial thermal manifestations including a cluster of hot springs with varied temperatures. Hammam Faraun area consists of the hottest spring in Egypt where the water temperature is 70°C. Conceptual as well as numerical models were made on the Hammam Faraun hot spring based on geological, geochemical, and geophysical data. The models show that the heat source of the hot spring is probably derived from high heat flow and deep water circulation controlled by faults associated with the opening of the Red Sea and Gulf of Suez rifts.  相似文献   

Discrimination between depositional environments using grain-size analyses     

RAMADAN ABU EL-ELLA  JAMES M. COLEMAN 《Sedimentology》1985,32(5):743-748

Grain-size analyses were performed on 84 samples from six environments in the Burdekin River Delta, NE Queensland, Australia. The data were subjected to a stepwise discriminant function analysis and canonical analysis which showed that the grain-size characteristics of the sediments are sufficiently distinctive to distinguish the six different environments of deposition. The resulting ‘reference set’ was then tested by plotting the grain-size characteristics of 66 samples from different environments of the Mississippi River Delta, Louisiana and Galveston Island, Texas. Seventy-four per cent of the North American samples were correctly classified.  相似文献   

Ray parameters of diffracted long period P and S waves and the velocities at the base of the mantle     

Abdel Hafiz Mula  Gerhard Müller 《Pure and Applied Geophysics》1980,118(2):1272-1292

The derivation of P and S velocities at the core-mantle boundary (CMB) from long-period diffracted waves by the use of the simple ray-theoretical formulav _CMB=r _c /p (v _CMB=velocity at the CMB;r _c =core radius;p=ray parameter) yields apparent velocity values which differ from the true velocities. Using a dominant period of about 20 sec for calculating theoretical seismograms, we found a linear relation between the apparent velocity and the average velocity in a transition zone at the base of the mantle with fixed velocity on top.The ray parameters determined from long-period earthquake data are found to be 4.540±0.035 and 8.427±0.072 sec/deg for P_diff and S_diff, respectively. These values yield apparent velocities of 13.378±0.103 for P and 7.207±0.062 km/sec for S waves. By means of the theoretical relation between apparent and average velocity and under the assumption of linear variation of velocity with depth, one can invert the apparent velocities into true CMB velocities of 13.736±0.170 and 7.320±0.124 km/sec. These results imply positive velocity gradients at the base of the mantle and hence no significant departures from adiabaticity and homogeneity.Contribution No. 211 of the Geophysical Institute, University of Karlsruhe.  相似文献   

U-Pb (zircon) ages for the gneissic terrane west of the Nile,southern Egypt     

M. Sultan  R. D. Tucker  Z. El Alfy  R. Attia  Abdel Ghany Ragab 《International Journal of Earth Sciences》1994,83(3):514-522

The first U-Pb zircon ages are reported for the gneissic bedrock inliers previously interpreted as part of the Nile Craton. The inliers crop out in the Egyptian Western Desert, east of the Uweinat area and west of the Eastern Desert. Multi- and single-grain zircon analyses of granitoid gneiss and migmatite from Gebel Um Shagir, Aswan, and another locality approximately 160 km south-west of Aswan, yield simple discordia with near modern day Pb loss trajectories, and the following Neoproterozoic crystallization ages: 626+4/–3, 634 ± 4 and 741 ± 3 Ma. In contrast, multi- and single-grain U-Pb analyses (zircon and sphene) from an anorthositic gabbro at Gebel Kamil (22°46N 26°21E) and an anorthosite at Gebel El Asr (22°46N 31°10E) yield Archean and Paleoproterozoic emplacement ages. The former yield a crystallization age of > 2.67 Ga and a metamorphic age of 2.0 Ga; the latter a metamorphic age of 0.69 Ga and an inheritance age of 1.9–2.1 Ga. Because high grade gneiss and migmatite of Neoproterozoic, Paleoproterozoic and Archean age crop out west of the Nile, pre-Neoproterozoic crust should no longer be identified by its metamorphic grade. By contrast, mapping the anorthosite and related rocks might provide first-order estimates for the extension of pre-Neoproterozoic crust in north-east Africa. It is suggested that Archean and Paleoproterozoic crust of the Uweinat and Congo Craton are contiguous because these U-Pb (zircon) data show no evidence for a Neoproterozoic thermal overprint in the Gebel Kamil area and there is no pronounced Neoproterozoic magmatic activity south of the Uweinat inlier and north of the Congo Craton.  相似文献   

Manganese deposits in a Carboniferous paleokarst profile,Um Bogma region,west-central Sinai,Egypt     

M. A. El Sharkawi  M. M. El Aref  A. Abdel Motelib 《Mineralium Deposita》1990,25(1):34-43

The Carboniferous carbonates of the Um Bogma Formation of the west-central Sinai include two rock successions. The lower succesion consists of karstic carbonates, intrakarstic products, weathering varieties, manganese deposits, and soil cover. The lower karstic rocks and the associated soil cover are preserved under a rhythmic alternation of dolostone and shale forming the upper rock succession of the Um Bogma Formation. The all over congruent relations between the manganese deposits and the fossilized karst profile, karst products, and the associated pedogenesis demonstrate the role of weathering in the accumulation of these deposits during Carboniferous karstification. It is clear that the manganese oxides were deposited during the mature stage of Carboniferous karstification, i.e., during the soil formation, preceeding initial diagenetic change of the karstic rocks and final deposition of the related late-diagenetic caliche cement. The geochemical behavior of Mn during the karstification and the microbiological processes involved in pedogenesis played an essential role in the concentration of the manganese ore in the subsoil horizon of the paleokarst profile. The Um Bogma Formation has been subjected to another episode of karstification during the Quaternary and resulted in lowering of the landforms of the Carboniferous carbonates and destruction of the Carboniferous karst and the associated manganese deposits in some localities.  相似文献   

Radon and thoron content in atmospheric air at Giza,Egypt     

Abdel Fattah El-Nadi  Hassan M. Omar 《Pure and Applied Geophysics》1960,45(1):261-266

Summary The radon and thoron content in atmospheric air at Giza was determined through the period from January (1958 to July 1959) by using the emanometrical technique. The concentration of radon and its decay products was equal to (88±4) 10^–18 Curie/c.c. and that of thoron and its decay products was equal to (51±11) 10^–18 Curie/c.c.  相似文献   

Biodegradation of municipal refuse and chicken manure in a winter-wheat ecosystem in Saudi Arabia     

H. M. Abdel Magid  R. E. A. Sabrah  R. K. Rabi  A. R. H. El Nadi  S. I. Abdel Aal 《Journal of Arid Environments》1993,25(4)

Addition and incorporation of organic fertilizers is known to improve the properties of agricultural soils. Therefore, during 22 weeks of field incubation we studied the biodegradation (measured by static absorption of CO₂) of two organic manures viz. municipal refuse and chicken manure incorporated into sandy soils, under sprinker irrigation, at the rates of 0, 16·5, 33·0, 49·5 and 66·0, and 0, 4·1, 8·25, 16·5, and 33·0 tonnes/ha, respectively.The results obtained indicated that the cumulative amount of CO₂ respired was linearly correlated with the rate of organic material applied (p < 0.001). Statistical analysis of the data obtained showed that both the intercept (rate of decomposition) and the slope (rate of reaction with time) increased with increasing rate of application of organic manure. The magnitude of increment was highest at the application rates of 33·0 and 8·25 tonnes/ha for municipal refuse and chicken manure, respectively. The rate of increment, generally, declined thereafter thus indicating that these two rates are the optimum levels of incorporation of the appropriate organic manures under the conditions of this study.The maximum organic-carbon mineralized, accounting for 10·5 and approximately 50%, was obtained at the optimum rates for municipal refuse and chicken manure, respectively. Both simple and multiple regression equations describing the relationship between soil temperature and soil-moisture content each separately and in combination, as independent variables, and the cumulative rate of CO₂ production were computed. A substantially strong relationship with soil temperature but inconsistent and contradicting results with soil moisture were obtained. Inclusion of soil temperature and moisture in a single model as an independent variable in relation to cumulative CO₂ as a dependent variable improved the soil moisture-CO₂ production relationship.  相似文献