Estimation of Hourly and Daily Global Solar Radiation at Clear Days Using an Approach Based on Modified Version of Gaussian Distribution     

S. M. El shazly 《大气科学进展》1996,13(3):349-358

The performance of two models,Jam and Baig,based on the modified version of Gaussian distribution function in estimating the daily total of global solar radiation and its distribution through the hours of the day from sunrise to sunset al any clear day is evaluated with our own measured data in the period from June 1992 to May 1993 in Qena Egypt The results show a high relative deviation of calculated values from measured ones,especially for Jain model,in the most hours of the day,except for those near to local noon.This misfit behavior is quite obvious in the early morning and late afternoon A new approach has been proposed in this paper to estimate the daily and hourly global solar radiation This model performs with very high accuracy on the recorded data in our region.The validity of this approach was verified with new measurements in some clear days in June and August 1994.The resultant very low relative deviation of the calculated values of global solar radiation from the measured ones confirms the  相似文献   

Hydrogeologic Units Of Lebanon     

Kamal Khair  Nizar Aker  Khalil Zahruddine 《Hydrogeology Journal》1992,1(2):34-49

Based on geomorphologic and hydrogeologic characteristics of its territory, Lebanon is divided into three provinces: the West Lebanon province, the Bekaa province, and the East Anti-Lebanon province. These provinces are subdivided into smaller hydrogeologic units, the basins and subbasins. Significant features used in the subdivision are faults, relief, anticlinal axes, river channels, and water divides. Recharge to groundwater is a percentage of the intake area, the percipitation rate over this area, and the infiltration rate of outcropping rocks. The amounts of recharged water over the three provinces are 1609, 914, and 19 Mm³, respectively. Discharge is surface water from springs and water wells along the Lebanese coast. The discharge from the Lebanese rivers exceeds 3700 Mm³/year, an appreciable amount of which comes from natural springs. The quantity of groundwater pumped by wells or flowing into neighboring countries and to the sea as submarine springs, may exceed 800 Mm³/year.  相似文献   

Paleogeography and paleomagnetism of the Nubian Sandstone Eastern Desert of Egypt     

E. M. El Shazly  Miroslav Krs 《International Journal of Earth Sciences》1973,62(1):212-225

The present work gives the results of the paleomagnetic investigations carried out on the Cretaceous Nubian Sandstone and associated volcanics and hematitic oolitic iron ores in the Eastern Desert of Egypt. The paleogeography of the Nubian Sandstone especially for the Eastern Desert is discussed in the light of the various geological data as well as the paleomagnetic results, both of which point to certain conceptions. The position of the paleoequator and paleolatitude 20° S were derived from the paleomagnetic data indicating that the Nubian Sandstone was originally deposited in the paleoequatorial to subequatorial zone. The paleomagnetic results corroborate previous African data that there has been no polar wandering and continental drift for Africa during 210 to 110 million years and extend this period to 85 million years.It is concluded that the Nubian Sandstone is deposited under tropical to subtropical climate and that it is formed under various continental conditions excluding eolian merging intermittently into shallow marine.

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Zusammenfassung Die vorliegende Arbeit ist das Ergebnis paläomagnetischer Untersuchungen, die in kretazischer Nubischer Serie und zugehörigen vulkanischen Gesteinen sowie in hämatitischoolithischen Eisenerzen in der östlichen Wüste in Ägypten durchgeführt wurden. Es wird die Paläogeographie der Nubischen Serie, besonders der östlichen Wüste, diskutiert, einmal anhand verschiedener geologischer Beobachtungen und darüber hinaus anhand der paläomagnetischen Daten; beides weist auf ähnliche Deutungen hin. Die Lage des Paläoäquators und des Paläobreitenkreises 20° S zeigt an, daß die Nubische Serie in der Umgebung des damaligen Äquators abgelagert wurde. Die paläomagnetischen Ergebnisse bestätigen frühere afrikanische Daten, nach denen keine Kontinentaldrift für diesen Raum zwischen 210 und 110 Mill. Jahren stattfand, und erweitern diese Periode bis 85 Mill. Jahre. Es wird angenommen, daß die Nubische Serie in tropischem bis subtropischem Klima abgelagert wurde, und zwar unter den verschiedensten kontinentalen Ablagerungsbedingungen.

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Résumé Le présent travail est le résultat des recherches paléomagnétiques effectuées sur le grès nubien crétacé, les volcanites associées et les minerais de fer hématitiques et oolithiques dans le désert oriental de l'Egypte. La paléogéographie du grès nubien, surtout celui du désert oriental, est discutée à la lumière des différentes observations géologiques variées et, en outre, des données paléomagnétiques; toutes deux concluent a la même signification. La position du paléoéquateur et de la paléolatitude 20° S montre que la série nubienne a été déposée dans le domaine proche de l'équateur relatif à cette époque.Les résultats paléomagnétiques corroborent les données africaines antérieures d'après lesquelles il n'y aurait pas eu, pour ces régions, de dérive continentale entre 210 à 110 millions d'années; ils prorogent cette période jusqu'à 85 millions d'années.On admet que le grès nbien fut déposé sous le climat tropical à sub-tropical et effectivement sous les différentes conditions de dépôt continentales.

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Present recharge of an aquifer in a semi-arid region: an example from the Turonian limestones of the Errachidia basin, Morocco     

A. El Ouali  J. Mudry  J. Mania  P. Chauve  N. Elyamine  M. Marzouk 《Environmental Geology》1999,38(2):171-176

 The Errachidia basin is composed of three superposed aquifers (Senonian, Turonian limestones and Infracenomanian). The Liassic limestone of the upper Atlas borders the northern part of the basin. The piezometric map of the Turonian aquifer displays a north-south flow, with an inflow area from the Atlas. This recharge hypothesis is demontrated by a discriminant analysis performed on chemical data: the majority of the spots are of sodium choride and hydrogenocarbonate types, while several boreholes are assigned to a calcium hydrogenocarbonate type Jurassic component. ¹⁸O measurements, using the Atlasic gradient δ¹⁸O=–4.18–0.0027 x elevation to estimate the recharge areas, confirm that the recharge area is the basin itself (<1100 m) on the Turonian outcrops, while in the confined part, the Turonian is recharged higher than 1400 m (corresponding to the Atlas). This contribution ranges from 56 to 85%, according to the situation versus the piezometric inflow area. The remainder represents infiltration and vertical leakage from the Senonian layers.  相似文献   

Geochemical Aspects of Hypogene Hydrothermal Alteration Zones in the Chol-qeshlaghi Area, NW Iran: Constrains on REEs     

Kamal SIAHCHESHM  Mohammad SHAHSAVANI BAMI 《《地质学报》英文版》2020,94(3):777-788

Chol-qeshlaghi altered area lies in the northwestern part of the post-collisional Urumieh-Dokhtar magmatic arc, NW Iran. Pervasive silicic, argillic, phyllic and propylitic altered zones appears to be intimately affiliated to the fluids derivative of upper Oligocene Khankandi granodiorite. This paper is dedicated to the identification of geochemical characteristics of hydrothermal alterations, focusing on the determination of the mass gains and losses of REEs, to gain significant insights regarding the chemical exchanges prevailed between the host rocks and hydrothermal fluids. The low pH and high activity of SO_4~(-2) ligands in silicic alteration fluids, resulting in depletion of entire REEs. Decreasing of LREEs appeared in argillic zone may attributed to reduce in adsorption ability of clay minerals in low pH; whereas HREEs enrichment in phyllic zone was inclined to put it down to the abundance of sericite(± Fe oxides). A significant reduction of Eu/Eu* ratio in silicic zone can be attributed to negligible sulfides and clay minerals as some effective agents in adsorption of released Eu~(+2). Factors such as changes in pH, the abundance of absorptive neomorph mineral phases, activity of ligands play an important role in controlling the distribution and concentration of REEs in Chol-qeshlaghi alteration system.  相似文献   

Eight new magnetic stars with large continuum depressions     

V. G. El’kin  D. O. Kudryavtsev  I. I. Romanyuk 《Astronomy Letters》2003,29(6):400-404

Observations with the 6-m telescope revealed eight new magnetic, chemically peculiar stars: HD 29925, HD 40711, HD 115606, HD 168796, HD 178892, HD 196691, HD 209051, and BD+32°2827. Zeeman observations of all these objects have been carried out for the first time. We selected candidates by analyzing the depression profile at a wavelength of λ5200 Å. This technique for selecting candidate magnetic stars was shown to be efficient: we found magnetic fields in 14 of the 15 objects that we selected for our observations with a Zeeman analyzer. A maximum longitudinal field strength B _e exceeding 8 kG was found in HD 178892; in HD 209051 and HD196691, B _e reaches 3.3 and 2.2 kG, respectively. For the remaining stars, we obtained lower limits of the longitudinal field (more than several hundred G).  相似文献   

Effect of seabed instability on fixed offshore platforms     

Yasser E. Mostafa  M. Hesham El Naggar   《Soil Dynamics and Earthquake Engineering》2006,26(12):1127-1142

Storms, hurricanes, and earthquakes may cause seabed instability, especially if the seabed is weak. The seabed instability, manifested in movement of soil layers, exerts lateral forces that may cause large stresses in offshore foundations. The induced stresses may compromise the stability of the foundation and supported structure. The effect of seabed instability on a fixed offshore structure is examined in this study. The method used accounts for soil nonlinearity, dynamic soil resistance, and pile–soil–pile interaction within the stable soil layer. Dynamic p–y curves, dynamic t–z curves and q–z curves have been used to simulate the soil resistance in the lateral and axial directions. The effect of different parameters that influence the response of offshore structures to seabed instability is evaluated. The parameters considered include the value of soil movement, the sliding layer depth, the wave loading, the pile flexibility, the soil movement profile, and the axial loading at the pile head. The response predicted using the proposed analysis compared well with that calculated using a boundary element solution for a case history of a failed offshore platform.  相似文献   

Urgent problems of groundwater quality     

I. S. Zektser  L. I. El’piner 《Water Resources》2006,33(6):711-712

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阿尔泰额尔齐斯带东段酸性岩墙群地球化学特征及其地质意义     

宫红良陈正乐  胡远清李丽赖新荣  马庆佑李玉英胡博  张文贵 《岩石学报》2007,23(5):889-899

野外地质调查发现在阿尔泰南缘额尔齐斯构造带东段、额尔齐斯活动断裂与富蕴-锡泊渡断裂之间发育了一套未变形的酸性岩墙群。岩墙群侵位于海西期片麻岩化花岗岩和上石炭统深变质的额尔齐斯组岩层中,薄片鉴定和岩石地球化学分析确定为具有细晶结构的流纹斑岩。岩石的SiO_2含量为70.9%～75.38%,K_2O Na_2O含量为7.55%～8.99%;大部分样品Na_2O>K_2O,里特曼指数值为1.8～2.5之间,Al_2O_3=12.80%～14.53%,A/CNK=0.9～1.1,NK/A=0.7～0.9,具有准铝质—弱过铝质、低镁、高钾钠、低钙和锶、高(Fe)_(mol)/(Mg)_(mol)特点,具A型花岗岩类特点,属于亚碱性脉岩。岩石轻稀土富集,大离子亲石元素相对富集,具有明显的中等负铕异常,壳源特征明显。锆石U-Pb二次粒子微探针测年显示岩墙群形成于277～286Ma。推断岩墙是阿尔泰海西期造山运动结束后,在拉张构造环境下的地壳局部熔融产物。  相似文献   

Post-collision neogene volcanism of the Eastern Rif (Morocco): magmatic evolution through time   总被引：6，自引：0，他引：6  

Samir El Bakkali  Alain Gourgaud  Jean-Louis Bourdier  Herv Bellon  Niyazi Gundogdu 《Lithos》1998,45(1-4):523-543

Neogene volcanism in the Eastern Rif (Morocco) comprises a series of calc-alkaline, potassic calc-alkaline, shoshonitic and alkaline volcanic rocks. According to new stratigraphical, along with new and previous chronological and geochemical data, the orogenic volcanism was successively (1) calc-alkaline (basaltic andesites and andesites: 13.1 to 12.5 Ma, rhyolites: 9.8 Ma), (2) K-calc-alkaline (basaltic andesitic to rhyolitic lavas and granodiorites: 9.0 to 6.6 Ma), and (3) shoshonitic (absarokites, shoshonites, latites, trachytes: 7.0 to 5.4 Ma). The later Pliocene volcanism was basaltic and alkaline (5.6 to 1.5 Ma). The calc-alkaline and K-calc-alkaline series exhibit lower K₂O (0.7–5.3 wt.%), Nb (8–19 ppm) contents and higher ⁸⁷Sr/⁸⁶Sr (0.70773–0.71016) than the shoshonitic series (K₂O: 2.4–7.2 wt.%, Nb: 21–38 ppm, ⁸⁷Sr/⁸⁶Sr: 0.70404–0.70778). Pliocene alkaline basalts have a sodic tendency (Na₂O/K₂O: 1.7–3.5), high Nb content (up to 52 ppm), and low ⁸⁷Sr/⁸⁶Sr ratio (0.70360–0.70413). The variations through time of K₂O, Nb and Sr isotopic ratio reflect different mantle sources: (i) calc-alkaline, potassic calc-alkaline and shoshonitic series are derived from a mantle source modified by older subduction, (ii) alkaline basalts are derived mainly from an enriched mantle source. Through time, incompatible elements such as Nb increased while ⁸⁷Sr/⁸⁶Sr decreased, suggesting a decreasing influence of metasomatized mantle (inherited subduction). Such evolution is related to the post-collision regimes operating in this area, and could be linked to the succession of extensional, compressional and strike-slip fault tectonics.  相似文献