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排序方式: 共有1422条查询结果,搜索用时 213 毫秒
1.
Alameer Zakaria Elaziz Mohamed Abd Ewees Ahmed A. Ye Haiwang Jianhua Zhang 《Natural Resources Research》2019,28(4):1385-1401
Natural Resources Research - An accurate forecasting model for the price volatility of minerals plays a vital role in future investments and decisions for mining projects and related companies. In... 相似文献
2.
Suhail Gumaan Masda Mashhoor Ahmed Al-Wardat Jiyaulla Khan Moula Khan Pathan 《天文和天体物理学研究(英文版)》2018,(6)
The best physical and geometrical parameters of the main sequence close visual binary system(CVBS), HIP 105947, are presented. These parameters have been constructed conclusively using Al-Wardat's complex method for analyzing CVBSs, which is a method for constructing a synthetic spectral energy distribution(SED) for the entire binary system using individual SEDs for each component star. The model atmospheres are in its turn built using the Kurucz(ATLAS9) line-blanketed plane-parallel models. At the same time, the orbital parameters for the system are calculated using Tokovinin's dynamical method for constructing the best orbits of an interferometric binary system. Moreover, the mass-sum of the components, as well as the ?θ and ?ρ residuals for the system, is introduced. The combination of Al-Wardat's and Tokovinin's methods yields the best estimations of the physical and geometrical parameters. The positions of the components in the system on the evolutionary tracks and isochrones are plotted and the formation and evolution of the system are discussed. 相似文献
3.
Ali Moamen Abdelmaksoud Ahmed Essa M. A. Abdelhady A. Darwish M. 《Natural Resources Research》2020,29(4):2575-2597
Natural Resources Research - Two main reservoirs are producing in Komombo Basin: the first one belongs to the C Member of the Six Hills Formation, and the second belongs to the Albian/Cenomanian... 相似文献
4.
Ali Moamen Abdelhady A. Abdelmaksoud Ahmed Darwish M. Essa M. A. 《Natural Resources Research》2020,29(2):1259-1281
Natural Resources Research - The Albian/Cenomanian reservoir is one of the two main reservoirs composing the petroleum system in the Komombo Basin. However, these reservoirs have not previously... 相似文献
5.
Infiltration into frozen soil plays an important role in soil freeze–thaw and snowmelt-driven hydrological processes. To better understand the complex thermal energy and water transport mechanisms involved, the influence of antecedent moisture content and macroporosity on infiltration into frozen soil was investigated. Ponded infiltration experiments on frozen macroporous and non-macroporous soil columns revealed that dry macroporous soil produced infiltration rates reaching 103 to 104 mm day−1, two to three orders of magnitude larger than dry non-macroporous soil. Results suggest that rapid infiltration and drainage were a result of preferential flow through initially air-filled macropores. Using recorded flow rates and measured macropore characteristics, calculations indicated that a combination of both saturated flow and unsaturated film flow likely occurred within macropores. Under wet conditions, regardless of the presence of macropores, infiltration was restricted by the slow thawing rate of pore ice, producing infiltration rates of 2.8 to 5.0 mm day−1. Reduced preferential flow under wet conditions was attributed to a combination of soil swelling, due to smectite-rich clay (that reduced macropore volume), and pore ice blockage within macropores. In comparison, dry soil column experiments demonstrated that macropores provided conduits for water and thermal energy to bypass the frozen matrix during infiltration, reducing thaw rates compared with non-macroporous soils. Overall, results showed the dominant control of antecedent moisture content on the initiation, timing, and magnitude of infiltration and flow in frozen macroporous soils, as well as the important role of macropore connectivity. The study provides an important data set that can aid the development of hydrological models that consider the interacting effects of soil freeze–thaw and preferential flow on snowmelt partitioning in cold regions. 相似文献
6.
This study aims at evaluating the global geoid model for a regional shoreline fitting using advanced soft computing techniques and global navigation satellite system/leveling measurements. Artificial neural networks, fuzzy logic, and least square support vector machine models are developed and used to fit the global geoid model for the north coastal Egyptian line. In addition, a novel estimation geoid model is designed and evaluated based on the latest global geoid models. The results of the three estimation models show that they can be used to correct the shoreline geoid model, in terms of root mean square error that ranges from 1.7 to 8.5?cm. Moreover, it is found that the least square vector machine model is a competitive approach with certain advantage in solving complex problems represented by missing data. 相似文献
7.
Sidali Kourdali Nabila Bounakous Abdellah Meknachi Bilal Zenati Ahmed Inal 《Ocean Science Journal》2020,55(4):521-536
Ocean Science Journal - Biological monitoring has become one of the most widely used approaches in aquatic monitoring. As a result, the effect of the xenobiotics entrained by the organic and... 相似文献
8.
Zakia MOKRANE Mustapha BOUDJENAH Yasmina BELKACEM ELHadi MORSLI Ahmed INAL Fahima BOUARAB 《资源与生态学报(英文版)》2019,(4)
浮游植物群的组成是沿海水域状况的极好指标。本研究的目的是探索阿尔及利亚沿海不同地区(东部、中部和西部)浅海沿岸地区浮游植物的空间变异性。浮游植物种群的定性和定量研究是在2012–2013年期间研究船GRINE BELKACEM在该区域采集样本的基础上进行的。定性研究的结果显示硅藻和甲藻具有显著的多样性,在总菌群中分别排名第一和第二(Fr50%)。这一发现也得到了2012年和2013年样本的丰度值的定量证实,这些丰度值大大超过了西部大多数地区的平均值(56%),并且在所有中心地区略高于52%,这代表了硅藻和甲藻两者之间的均衡分布。甲藻对东部地区的数量丰富度(60%)有显著贡献。在东部地区Dia/Dino指数所记录到的最小值也证实了甲藻在该区域的主导地位,特别是在Skikda(0.31)地区更是如此。本文的研究结果还揭示了其他群体(如cocolithophoridae和euglenophyceae)存在的比例较小。 相似文献
9.
Houda El Kerni Hasnaa Chennaoui Aoudjehane David Baratoux Mohammed Aoudjehane Andr Charrire Hassan Ibouh Pierre Rochette Yoann Quesnel Minoru Uehara Thomas Kenkmann Gerwin Wulf Michael Poelchau Van Binh Nguyen Maria Aboulahris Samira Makhoukhi Georges Aumaître Didier Bourls Karim Keddadouche 《Meteoritics & planetary science》2019,54(10):2483-2509
Since the discovery of shatter cones (SCs) near the village of Agoudal (Morocco, Central High Atlas Mountains) in 2013, the absence of one or several associated circular structures led to speculation about the age of the impact event, the number, and the size of the impact crater or craters. Additional constraints on the crater size, age, and erosion rates are obtained here from geological, structural, and geophysical mapping and from cosmogenic nuclide data. Our geological maps of the Agoudal impact site at the scales of 1:30,000 (6 km2) and 1:15,000 (2.25 km2) include all known occurrences of SCs in target rocks, breccias, and vertical to overturned strata. Considering that strata surrounding the impact site are subhorizontal, we argue that disturbed strata are related to the impact event. Three types of breccias have been observed. Two of them (br1‐2 and br2) could be produced by erosion–sedimentation–consolidation processes, with no evidence for impact breccias, while breccia (br1) might be impact related. The most probable center of the structure is estimated at 31°59′13.73?N, 5°30′55.14?W using the concentric deviation method applied to the orientation of strata over the disturbed area. Despite the absence of a morphological expression, the ground magnetic and electromagnetic surveys reveal anomalies spatially associated with disturbed strata and SC occurrences. The geophysical data, the structural observations, and the area of occurrence of SCs in target rocks are all consistent with an original size of 1.4–4.2 km in diameter. Cosmogenic nuclide data (36Cl) constrain the local erosion rates between 220 ± 22 m Ma?1 and 430 ± 43 m Ma?1. These erosion rates may remove the topographic expression of such a crater and its ejecta in a time period of about 0.3–1.9 Ma. This age is older than the Agoudal iron meteorite age (105 ± 40 kyr). This new age constraint excludes the possibility of a genetic relationship between the Agoudal iron meteorite fall and the formation of the Agoudal impact site. A chronolgy chart including the Atlas orogeny, the alternation of sedimentation and erosion periods, and the meteoritic impacts is presented based on all obtained and combined data. 相似文献
10.
Al-Djazouli Mahamat Ouchar Elmorabiti Karim Rahimi Abdelmejid Amellah Omayma Fadil Omer Abdelrahim Mohammed 《GeoJournal》2021,86(4):1881-1894
GeoJournal - The delineation of favourable areas of water potentials and their management must be based on rigorous scientific studies. Thus, geographic information system (GIS) and remote sensing... 相似文献