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Petrological and geochemical characteristics of the Ordovician-Silurian black shale in eastern Sichuan and western Hubei,South China:Differential sedimentary responses to tectonism and glaciation

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Journal of Palaeogeography 2023年第1期12卷 129-152页

作者： Quan-Sheng Cai Ming-Yi Hu Oumar ibrahima Kane Zhi Yang Ya-Ru Wen Qun Luo Ming-Tao Li Zhong-Gui Hu Qing-Jie Deng Cooperative Innovation Center of Unconventional Oil and Gas Yangtze University(Ministry of Education and Hubei Province)Wuhan 430100Hubei ProvinceChina School of Geosciences Yangtze UniversityWuhan 430100Hubei ProvinceChina Key Laboratory of Tectonics and Petroleum Resources of Ministry of Education China University of Geosciences(Wuhan)Wuhan 430074Hubei ProvinceChina Natural Gas Geology Key Laboratory of Sichuan Province Chengdu 610500Sichuan ProvinceChina Research Institute of Petroleum Exploration and Development PetroChinaBeijing 100083China Hubei Geological Survey Wuhan 430034Hubei ProvinceChina Institute of Unconventional Science and Technology China University of Petroleum(Beijing)Beijing 102249China

During the Ordovician-Silurian transition period,the Yangtze area experienced significant environmental changes,which were recorded by the widely distributed black shale of the Upper Ordovician Wufeng and Lower Silurian Longmaxi ***,the petrological and geochemical analyses of the Upper Ordovician-Lower Silurian black shale in Well JY1(eastern Sichuan Basin)and Well YY2(western Hubei Province)drill cores show that there are some significant differences with respect to lithology,thickness,and geochemical characteristics despite the long-term similar variation trend in petrology and *** may suggest some major environmental changes and their differential influence on black shale deposition in the Yangtze *** on the analyses of lithology,total organic carbon(TOC),Mo_(EF),and U_(EF),four long-term sedimentary cycles(one for the Wufeng Formation and three for the Longmaxi Formation)were identified in Well *** Well YY2,only three long-term sedimentary cycles can be recognized(one for the Wufeng Formation and two for the Longmaxi Formation).Different from the gradual increase of the geochemical proxies(such as TOC,MoEF,and NiEF)followed by an abrupt decrease in the Wufeng Formation,these proxies of the Silurian sedimentary cycles in both wells exhibit an abrupt increase at the base followed by a gradual decrease,showing that controlling mechanisms for the Lower Silurian black shale deposition in the study areas were different from those of the Upper Ordovician black ***,the black shale of each Silurian cycle in Well JY1 is much thicker than that in Well *** with the thick silty mudstone developed in Well JY1 during the Rhuddanian-Aeronian transition,there is a stratigraphic gap in Well YY2 except for a thin calcareous dolostone formed in a strongly restricted *** differences indicate that tectonism and glacial eustasy should be the key factors for black shale development,but their influences on the depo

关键词： Ordoviciane-Silurian transition Black shale Sedimentary differences Tectonism Paleoclimate Sea-level change Yangtze area

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冷室散热与天然生物质材料保温性能分析

冷室散热与天然生物质材料保温性能分析

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作者： ibrahima Conté 清华大学

学位级别：硕士

本文针对冷藏冷库热性能和利用天然生物质材料保温进行理论分析和实验研究。全文共5章,系统地阐明论文工作和取得初步成果。第1章为研究背景,介绍本研究意义和目的,分析综述相关研究工作结果和存在的问题,提出本论文的的具体研究思路和... 详细信息

本文针对冷藏冷库热性能和利用天然生物质材料保温进行理论分析和实验研究。全文共5章,系统地阐明论文工作和取得初步成果。第1章为研究背景,介绍本研究意义和目的,分析综述相关研究工作结果和存在的问题,提出本论文的的具体研究思路和内容。第2章针对冷库的实际工作情况,详细分析比较不同冷却负荷和条件下的制冷保温性能。第3章为几种天然生物质材料导热系数的实验和理论模型研究。第4章用实验分析的方法,研究了材料的吸水性。第5章是本文工作的总结和讨论,提出推广使用天然生物质材料作为低温绝热材料的建议和应注意的相关问题。

关键词： Refrigeration Coldstore Cooling Loads Thermal Insulation Moisture Absorption Coconut fibers Groundnut Coquets

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Calculations Energy of the (nl2) 1LπDoubly Excited States of Two-Electron Systems via the Screening Constant by Unit Nuclear Charge Formalism

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Journal of Modern Physics 2020年第11期11卷 1891-1910页

作者： Momar Talla Gning ibrahima Sakho Malick Sow Department of Experimental Sciences UFR Sciences and Technologies University of Thies Thies Senegal Atoms Laser Laboratory Department of Physics Faculty of Sciences and Technologies University Cheikh Anta Diop Dakar Senegal

In this work, the total energies of doubly excited states (ns2) 1Se, (np2) 1De, (nd2) 1Ge, (nf2) 1Ie, (ng2) 1Ke, and (nh2) 1Me of the helium isoelectronic sequence with Z ≤ 10 are calculated in the framework of the variational method of the Screening Constant by Unit Nuclear Charge (SCUNC). These calculations are performed using a new wavefunction correlated to Hylleraas-type. The possibility of using the SCUNC method in the investigation of high-lying Doubly Excited States(DES) in two-electron systems is demonstrated in the present work in the case of the (nl2) 1Lπ doubly excited states, where accurate total energies are tabulated up to n = 20. All the results obtained in this paper are in agreement with the values of the available literature and may be useful for future experimental and theoretical studies on the doubly excited (nl2) 1Lπ states of two-electron systems.

关键词： Doubly Excited States Helium-Like Systems Screening Constant by Unit Nuclear Charge (SCUNC) Wave Functions Correlated Total Energy

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Temperature Effect on Capacitance of a Silicon Solar Cell under Constant White Biased Light

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World Journal of Condensed Matter Physics 2016年第3期6卷 261-268页

作者： ibrahima Diatta ibrahima Ly Mamadou Wade Marcel Sitor Diouf Senghane Mbodji Grégoire Sissoko Physics Department Faculty of Sciences and Techniques University of Cheikh Anta Diop Dakar Senegal Electromechanical Engineering Department Polytechnic School of Thies University Thies Senegal University of Alioune DIOP Bambey Senegal

In static regime with polychromatic illumination, using the expression of the solar cell capacitance to determine the silicon solar cell capacitance C0(T) in short-circuit, is the purpose of this article. The expression of the excess minority carries density δ(x) from the continuity equation. The expression of δ(x) is used to determine the photovoltage expression. The capacitance efficiency dependence on Xcc(T) is studied. Xcc(T) is the abscissa of the maximum of δ(x).

关键词： Solar Cell Capacitance Temperature

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The Magnetic Field as Trigger for Disturbances of a Flow of a Newtonian Fluid through a Cylindrical Pipe with a Horizontal Axis

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Modern Mechanical Engineering 2022年第4期12卷 83-97页

作者： ibrahima Kama Mamadou Lamine Sow Cheikh Mbow Department of Physics University Cheikh Anta Diop (UCAD) Dakar Senegal

A Fourrier Petrov Galerkin spectral method is described for high accuracy computation of linearized dynamics for flow in a circular pipe. The code used here is based on solenoidal velocity variables. It is written in FORTRAN. Systematic studies are presented on the dependence of eigenvalues and other quantities on the axial and azimuthal wave number;the reynolds’ number Re and a new none-dimensional number Ne. The flow will be considered stable if all the real parts of the eigenvalues are negative and unstable if only one of them is positive.

关键词： Newtonian Fluids Magnetic Field Linear Stability Petrov-Galerkin Generalized Eigenvalue Problem

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随机延迟微分方程隐式单步法的收敛性

随机延迟微分方程隐式单步法的收敛性

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作者： SIDIBE ibrahima（易马）哈尔滨工业大学

学位级别：硕士

本文主要研究了随机延迟微分方程数值方法的相容性和收敛性。作为重要数学模型的随机延迟微分方程广泛应用于经济学、生物学、医学等领域。由于很难获得随机延迟微分方程的显示解,构造适当的数值方法和研究数值解的性质成为既有重大理... 详细信息

本文主要研究了随机延迟微分方程数值方法的相容性和收敛性。作为重要数学模型的随机延迟微分方程广泛应用于经济学、生物学、医学等领域。由于很难获得随机延迟微分方程的显示解,构造适当的数值方法和研究数值解的性质成为既有重大理论意义又有实际价值的研究课题。第一章介绍了本文的主要研究工作。第二章叙述了随机积分和伊藤—泰勒展开的基本理论知识。第三章是本文的主要研究内容。首先,回顾了随机延迟微分方程解析解和数值解的基本理论。其次,研究了随机延迟微分方程θ-方法的相容性与收敛性。证明了如果方程系数满足全局Lipschitz条件、线性增长条件、转移项系数一、二阶导数的一致有界性、初始条件满足H(o|¨)lder连续性,则θ-方法是相容的;证明了如果方程系数满足全局Lipschitz条件、线性增长条件、初始条件满足H(o|¨)lder连续性、则θ-方法是收敛的,且收敛阶为12阶。最后,研究了隐式一步泰勒方法的收敛性。

关键词：随机延迟微分方程 θ-方法伊藤—泰勒展开收敛性相容性

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Petrography, Geochemistry and Relative Chronology of Quaternary Volcanic Formations in the Mermoz and Fann Sectors, West Senegal

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International Journal of Geosciences 2023年第8期14卷 733-766页

作者： Moussa Fall ibrahima Labou Papa Moussa Ndiaye Department of Geology Faculty of Science and Technology Cheikh Anta Diop University Dakar Senegal National Superior School of Mines and Geology Cheikh Anta Diop University Dakar Senegal

Detailed work on Quaternary volcanism has been carried out in the Mermoz and Fann sectors of western Senegal. In the Mermoz sector, the main emission zone is a collapsed crater located at the intersection of three major fractures: NE-SW, NW-SE and N-S. The lithological succession in this Mermoz sector comprises, from bottom to top: 1) a substratum with at its base Eocene limestones on which lie Quaternary sands surmounted by stratified tuffs;2) a vesicular ball dolerite which deforms the stratified tuffs;3) a dark early breccia;4) two generations of basanites: the first is vesicular, the second non-vesicular;5) a clear intermediate breccia and finally 6) a late breccia. The Fann sector contains several emission zones, most of which are currently located in the ocean. The lavas may have reached the coast through E-W and NE-SW faults. The lithological succession includes from bottom to top: 1) scoria-rich early volcanic breccias;2) a first generation of non-vesicular mesocrate dolerite (D1);3) a second generation of melanocrate vesicular dolerite (D2);4) basanites and finally 5) a late breccia. The geochemical characteristics of the lavas studied are compatible with a very enriched and very deep magmatic source of the garnet lherzolite type located in the lower mantle. The magma from this source would have risen in the form of mantle plumes through major NE-SW and E-W faults in a continental intraplate context.

关键词： Quaternary Volcanism Western Senegal Emission Zone Geochemistry Con-tinental Intraplate

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Comparative Geochemical Study of the Tertiary and Quaternary Lavas of Western Senegal and the Cape Verde Islands: Geodynamic Implications

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International Journal of Geosciences 2015年第11期6卷 1193-1213页

作者： Diomaye Yatte Dinna Pathé Diallo ibrahima Sagna Département de Géologie Université Cheikh Anta Diop Dakar Sénégal Institut Fondamental d’Afrique Noire (IFAN) Université Cheikh Anta Diop Dakar Sénégal

The western area of Senegal was the site of a basic volcanism in the Tertiary and Quaternary. That volcanism had caused the formation of alkaline olivine basalts, basanites and nephelinites from microlitic and porphyritic texture to dolerite texture. The geochemistry of major elements shows that the Quaternary basalts are more aluminous and more siliceous, but they contain less magnesium, less iron and less calcium than the Tertiary basalts. Two types of basalt occur here, based on the characteristics of the major elements in the Tertiary lavas: the highly undersaturated basalts of the Cape Verde Peninsula and the slightly undersaturated basalts of the Thiès Plateau. The characteristics of the trace elements reveal shallow interactions due to the contamination and/or assimilation, and to the fractional crystallization, but not due to the heterogeneity of the source. The strong enrichment in light rare earth elements (LREE) and the slight enrichment in heavy rare earth elements (HREE), the anomalies which are negative in K and Pb and positive in Nb, Ta and Eu of the Tertiary and Quaternary basalts of Western Senegal and similar anomalies of the same elements (Pb not analyzed) described in the Cape Verde islands, allow us to establish links between the petrogenetic mechanisms that had caused the formation of the basalts of this Islands and Western Senegal. Moreover, the volcanic activity in Western Senegal (of continental lntraplate type) and that of the Cape Verde Islands (oceanic intraplate type) are probably related to the hot spot located on the vertical of the Cape Verde.

关键词： Western Senegal Basalts Tertiary Quaternary Cape Verde

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Spatial Distribution of Cordex Regional Climate Models Biases over West Africa

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International Journal of Geosciences 2015年第9期6卷 1018-1031页

作者： Alioune Badara Sarr Moctar Camara ibrahima Diba Laboratoire d’Océanographie des Sciences de l’Environnement et du Climat (LOSEC) Université Assane SECK de Ziguinchor Ziguinchor Senegal

The objective of this work is to analyze the spatial distribution of biases of nine (9) regional climate models (RCMs) and their ensemble average used under the framework of COordinated Regional climate Downscaling EXperiment (CORDEX) project over West Africa during the summer period. We assessed the ability of RCMs to represent adequately West African summer rainfall by analyzing some statistical parameters such as the relative bias, the standard deviation, the root mean square error (RMSE) and the correlation coefficient between observation data (GPCP used as reference) and regional climate models outputs. We first analyzed the relative bias between GPCP climatology and the other available observed data (CRU, CMAP, UDEL, GPCC, TRMM and their ensemble mean). This analysis highlights the big uncertainty on the quality of these observed rainfall data over West Africa which may be largely due to the rarity of?in situ?measurement data over this region. The statistical analysis with respect to GPCP rainfall shows the presence of large relative bias values over most part of West Africa for engaged RCMs. However their ensemble mean outperforms individual RCMs by exhibiting the weakest relative change. The RMSE values are weak over West Africa except over and off the Guinea highlands for RCMs and the Era-interim reanalysis. The spatial distribution of the coefficient of correlation between the observation data and RCMs shows that all models (except HIRHAM) present positive values over the Northern Sahel and the Gulf of Guinea. The model of the DMI exhibits the weakest values of correlation coefficient. This study shows that RCMs simulate West African climate in a satisfactory way despite the fact that they exhibit systematic biases.

关键词： CORDEX Regional Climate Models Rainfall

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Impacts of the Sahel-Sahara Interface Reforestation on West African Climate: Intra-Annual Variability and Extreme Temperature Events

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Atmospheric and Climate Sciences 2019年第1期9卷 35-61页

作者： ibrahima Diba Moctar Camara Arona Diedhiou Laboratoire d’Océanographie des Sciences de l’Environnement et du Climat (LOSEC) UFR Sciences et Technologies Université A. SECK de Ziguinchor Ziguinchor Sénégal IRD CNRS Grenoble INP IGE Université Grenoble Alpes Grenoble France

The impacts of the reforestation of the Sahel-Sahara interface on the seasonal distribution of the surface temperature and thermal extremes are studied in the Sahel (West African region lying between 11°N and 18°N). We performed a simulation with the standard version of the RegCM4 model followed by another one using the altered version of the same model taking into account an incorporated forest. The impacts of the vegetation change are assessed by analyzing the difference between the two runs. The reforestation may influence strongly the frequency of warm days (TG90P) and very warm days (TX90P) by decreasing it over the reforested zone from March to May (MAM) and the entire Sahel during the June-August (JJA) period. These TG90P and TX90P indices decrease may be due to the strengthening of the atmospheric moisture content over the whole Sahel region and the weakening of the sensible heat flux over the reforested zone. The analysis also shows a decrease of the TN90P indice (warm nights) over the Sahel during the wet season (JJA) which could be partly associated with the strengthening of the evapotranspiration over the whole Sahel domain. The analysis of additional thermal indices shows an increase of the tropical nights over the entire Sahel from December to February (DJF) and during the warm season (MAM). The strengthening of the tropical night is partly associated with an increase of the surface net downward shortwave flux over the reforested zone. When considering the heat waves, an increase (a decrease) of these events is recorded over the southern Sahel during JJA and SON periods (over the whole Sahelian region during DJF), respectively. Changes in latent heat flux appear to be largely responsible for these extreme temperatures change. This work shows that the vegetation change may impact positively some regions like the reforested area by reducing the occurrence of thermal extremes;while other Sahel regions (eastern part of the central Sahel) could suff

关键词： RegCM4 Reforestation Heat Waves Sahel

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