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Thermomechanical Characterization of Three Soils of Abeche in Chad

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Open Journal of Civil Engineering 2024年第3期14卷 348-362页

作者： Mahamat Saleh Abdel-khadir Abdallah Dadi Mahamat Abderahman Adoum Oumar Mahamoud Youssouf Khayal Salif Gaye Energy and Materials Research Laboratory (LREM-InSTA) National Higher Institute of Science and Technology of Abch Abch Chad Faculty of Physics University of NDjamena NDjamena Chad Laboratory of Energy Electricity and Economic Materials (LM3E) Iba Der Thiam University of This This Senegal

The study carried out concerns the valorization of agricultural waste for the development of biosourced materials that can be used as insulation in homes. This article is devoted to the influence of gum arabic on the mechanical and thermal properties of clay soils in the town of Abéché. The mechanical tests were carried out using the CBR press equipped with two devices (bending device and compression device). Thermal property such as thermal conductivity was determined by the hot wire method and thermal resistance was derived by calculation. Thus, the tests were carried out on test pieces made from a mixture of clay and gum arabic in solution. The experimental program includes seven formulations (0%, 2%, 4%, 6%, 8%, 10% and 12%). The results obtained showed that the best flexural and compressive strengths are obtained by using gum arabic with a rate of 8% and a maximum stress of 4.3 MPa. In addition, the thermal results also showed that the thermal conductivity decreases when the percentage of gum arabic increases, which makes it possible to increase the thermal resistance, thus confirming the capacity of gum arabic to provide thermal insulation.

关键词： Soils Mechanical Characterization Thermal Characterization Thermal Conductivity Thermal Resistance

Hygrothermal Properties of a Composite Based on Clay Soils and Diatomite

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Open Journal of Civil Engineering 2024年第3期14卷 363-373页

作者： Togdjim Jonas Malloum Soultan Modjinguem F. Ronelngar Mahamat S. Abdel-khadir Alexis M. nanimina Michel Querry Mechanical Engineering Department Higher National Institute of Sciences and Techniques of Abch Abch Chad Technology Department University of NDjamena NDjamena Chad national Center for Development Research (CnRD) NDjamena Chad Mechanical Department National Institute Superior of Sciences Appliqued Lyon France

The purpose of this paper is to make a contribution to the use of diatomite as a mineral additive in the composition of compressed earth blocks. The aim is to study the influence of diatomite on the hygrothermal behaviour of composites based on clay soils. For this reason, two clay soils with different physicochemical and mineralogical compositions were incorporated with diatomite at percentages ranging from 5% to 50% with a step of 5 to produce compressed earth blocks. After assessing the hydric and thermal characteristics of the composites, it was found that the incorporation of diatomite into the clay matrix favours the absorption of water by capillary action for all the composites. The diatomite-amended blocks subjected to the rain erosion test were less eroded than the unamended blocks. In addition, BYD composites were found to be more resistant than BTD composites, due to the high percentage of clay in T soil. The thermal conductivity of the latter decreases respectively from 0.72 to 0.29 W/m∙K for BTD composites and from 0.52 to 0.21 W/m∙K for BYD composites. This reduction proves the thermal insulating properties of diatomite. Despite the high capillary absorption capacity of these composites, they have good thermal properties, enabling them to be used in the construction of buildings for improved indoor thermal comfort.

关键词： Clay Soil Diatomite Capillary Absorption Erodibility and Thermal Conductivity

Thermophysical Characterization of Local Materials from a Locality in Chad for Use in Eco-Building

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Open Journal of Civil Engineering 2024年第3期14卷 486-497页

作者： Abderahman Adoum Oumar Malloum Soultan Abdallah Dadi Togdjim Jonas Mahamat Saleh Abdel-khadir Mahamoud Youssouf Khayal Salif Gaye Laboratoire de Recherche en Energtique et Matriaux (LREM) de lInSTA Institut National Suprieur des Sciences et Techniques dAbch Abch Chad Ecole Doctorale Science Technique et Environnement Universit de NDjamena NDjamena Tchad Laboratoire CABET (Construction Alternative Basse Energie au Tchad) NDjamena Chad Laboratoire de Matriaux dnergtique dlectricit et dconomie (LM3E) Universit Iba Der Thiam de This This Sngal

With the aim of enhancing the value of local building materials, the subject of this paper is a thermophysical study of natural Chadian clay from the eastern region of Chad, “Abeche”. Samples were taken from a brickwork in Abeche from a depth of 1 m, then using a clay brick-making press, 4 × 5 × 8 cm3 clay test tubes were made with 2%, 4%, 6% and 8% cow dung, and a 100% clay sample was used as a control. These samples underwent thermophysical characterization using the hot-wire method with a hot-plane option, yielding results that could improve thermophysical performance. The thermal conductivity of the test sample is in the order of 0.715 to 0.420 W/m. K, at 8% for cow dung, so the addition of cow dung as a percentage in the clay matrix enabled us to obtain various satisfactory thermal parameters.

关键词： Soils Characterization Thermophysical Local Building

Interest of Cardiac Rehabilitation in Patients with Heart Disease in a Cardiology Department in Senegal

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World Journal of Cardiovascular Diseases 2024年第4期14卷 217-227页

作者： Awa Ba-Diop Abdou khadir Sow Rim Mohamed Khaled Mor Diaw Mame Saloum Coly Fulgence Abdou Faye Amadou ndiadé Bamba Gaye Abdoulaye Ba Abdoulaye Samb Laboratory of Physiology and Functional Explorations Department of Medicine Alioune Diop University of Bambey Bambey Senegal IRL3189 Environment Health Societies CNRS-UCAD Dakar Senegal The African Research network noncommunicable Diseases Dakar Senegal Laboratory of Physiology and Functional Explorations FMPOS UCAD Dakar Senegal Laboratory of Physiology and Functional Explorations UFR Sant&#233 UAS of Thi&#232s Thi&#232s Senegal InSERM U970 Team 4 Paris France

Cardiac rehabilitation helps improve the prognosis and quality of life for patients with heart disease. To show its interest in the African context, in the management of heart disease, a prospective study was carried out. Its objective was to evaluate the effects of physical rehabilitation on cardiac function. Methods: Patients were evaluated at the beginning and at the end of cardiovascular rehabilitation by cardiovascular, biological, and echocardiographic parameters including the size of the heart chambers, the kinetics of the walls, and the systolic function of the ventricles. Results: The study involved 12 patients, 67% of whom were men. After cardiac rehabilitation, the mean hemodynamic constants had not been significantly modified. However, a significant decrease in Total-Cholesterol, LDL-Cholesterol and triglyceride levels was noted. Mean fasting blood sugar decreased from 1.25 ± 0.48 g/L to 0.92 ± 0.18 g/L and glycated hemoglobin from 7.72% ± 0.01% to 6.45% ± 0.008%. The echocardiographic parameters studied showed an improvement in the dilation of the heart chambers in 8.33% of the patients, the normalization of the ejection fraction of the left ventricle in 16% patients, the improvement of the kinetic disorders in 16% of patients and recovery of right ventricular systolic function in all patients. Conclusion: Cardiac rehabilitation as a secondary preventive measure for cardiovascular disease has contributed significantly to improving the clinico-biological parameters of the disease.

关键词： Cardiac Rehabilitation Heart Disease Cardiovascular Disease

Respiratory Flow Rates of Metal Welders Compared to a Population not Exposed to Metal Welding Dust

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Open Journal of Respiratory Diseases 2024年第2期14卷 51-59页

作者： Robert Faomowe Foko Abdou khadir Sow Awa Ba Mor Diaw Fatoumata Bah Mame Saloum Coly Absa Lam Cheikh Diop Aminata Toure Abdoulaye Ba Abdoulaye Samb Arame Mbengue Mathilde Cabral Mamadou Fall Laboratory of Toxicology and Hydrology Faculty of Medicine Pharmacy and Odontostomatology Cheikh Anta Diop University of Dakar Dakar-Fann Senegal Laboratory of Physiology and Functional Exploration Faculty of Medicine Pharmacy and Odontostomatology Cheikh Anta Diop University of Dakar Dakar-Fann Senegal Laboratory of Physiology and Functional Exploration Alioune DIOP University of Bambey Bambey Senegal Laboratory of Physiology UFR of Health Sciences Functional Exploration Department Thies Regional Hospital Center Thies Senegal

Background: The welding trade includes many industrial activities in both the formal and informal sectors. Workers in this professional environment do not have access to individual and collective means of protection adapted to the activity, which exposes them to the dust emitted during their activity and therefore contributes to increasing the risk of developing respiratory disorders in this population. Objective: Our study aimed to evaluate the ventilatory function of metal welders in the city of Dakar. Method: This was a comparative study based on the analysis of the spirometric parameters of metal welders working in the city of Dakar (Senegal) with those of a control group of the same kind, selected from the general population. Measurements of forced expiratory volume in the first second (FEV1), forced vital capacity (FVC), peak expiratory flow (PEF) and maximum mid expiratory flow (MMEF) were measured. Results: A total of 75 men between the ages of 19 and 61 were recruited and divided into two groups (43 controls and 32 welders). The welding population had more frequent distal and central obstructions and pulmonary restriction compared to the control group. The metals most commonly used by welders were aluminum for welders who had an obstruction, while for those who had a restriction, iron was the most used metal. Signs of metal fever were frequently found in welders, especially those with ventilatory disorders. Conclusion: The prevalence of respiratory disorders observed is close to that observed in industrial environments, where exposure levels are the highest. The lack of personal protective equipment could also be a significant risk factor in the development of these disorders.

关键词： Welder Occupational Exposure Spirometric Disorder Metal Fever Dakar

Contribution of High Sensible C-Reactive Protein (hsCRP) in the Assessment of the Risk of Onset of Type 2 Diabetes and Its Cardiovascular Complications

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Journal of Diabetes Mellitus 2024年第2期14卷 95-107页

作者： Maïmouna Touré Léopold ngor Sène Jean Pierre Diagne Demba Diédhiou Souleymane Thiam Abdou khadir Sow Mor Diaw Aïssatou Seck Salimata Diagne Houndjo Abdoulaye Ba Abdoulaye Samb Fatou Diallo-Agne Modou Oumy Kane Laboratoire de Physiologie et d’ Explorations Fonctionnelles Physiologiques Facult&#233 de M&#233decine de Pharmacie et d&#8217OdontoStomatologie (FMPOS) Universit&#233 Cheikh Anta Diop (UCAD) Dakar S&#233n&#233gal IRL3189 &#8220Environnement Sant&#233 Soci&#233t&#233&#8221 CNRS CNRST Bamako-UCAD Facult&#233 de M&#233decine de Pharmacie et d&#8217OdontoStomatologie (FMPOS) Universit&#233 Cheikh Anta Diop (UCAD) Dakar S&#233n&#233gal Laboratoire Privé de Biologie General Kaolack S&#233n&#233gal Centre Hospitalier Universitaire (CHU) Abasse ndao Universit&#233 Cheikh Anta Diop (UCAD) Dakar S&#233n&#233gal Laboratoire de Biochimie et de Biologie molé culaire Facult&#233 de M&#233decine de Pharmacie et d&#8217OdontoStomatologie (FMPOS) Universit&#233 Cheikh Anta Diop (UCAD) Dakar S&#233n&#233gal Laboratoire de Physiologie Pharmaceutique Facult&#233 de M&#233decine de Pharmacie et d'OdontoStomatologie (FMPOS) Universit&#233 Cheikh Anta Diop (UCAD) Dakar S&#233n&#233gal

Background: Type 2 diabetes is a metabolic disease characterized by chronic hyperglycemia. The latter plays an essential role in inflammation by stimulating the production of pro-inflammatory cytokines or by increasing their secretion by an oxidative mechanism. These cytokines control the hepatic synthesis of an inflammatory protein called C-Reactive Protein (CRP). High or average values of CRP would have a predictive value of cardiovascular diseases and type 2 diabetes. The relationship between low CRP values and the risk of developing type 2 diabetes and its cardiovascular complications is not sufficiently studied. The hsCRP could serve as a predictive biomarker of risk of onset, follow-up and prognosis for type 2 diabetes and its cardiovascular complications. To answer this problem, we conducted this study, the aim of which was to study the predictive role of hsCRP in the risk of occurrence of type 2 diabetes and its cardiovascular complications. Materials and Methods: This is a prospective and cross-sectional case-control study involving 200 participants including 100 control women and 100 women with type 2 diabetes (mean age was respectively 49.89 years ± 8.26 & 51.92 years ± 7.18;p = 0.066). The interviews were conducted on the basis of a questionnaire. Physical examination collected biometric data and cardiovascular constants. The biochemical parameters such as hsCRP were analyzed by an automated Abbott device. Results: We noted that hsCRP was significantly higher in type 2 diabetic subjects compared to control subjects (p (rho = 0.40, p systolic blood pressure (rho = 0.30, p = 0.003), diastolic blood pressure (rho = 0.28, p = 0.006), total body fat (rho = 0.48, p Conclusion: hsCRP has a prognostic value in the evaluation of cardiovascular risk. It seems to play an important role in the pathogenesis of type 2 diabetes mellitus and its cardiovascular complications. It could thus be considered as a biomarker for the screening, monitoring and prognosis of type 2

关键词： hsCRP Biomarker Inflammation Type 2 Diabetes

Thermal Analysis of a Phase Change Material Based Heat Sink for Cooling Protruding Electronic Chips

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Journal of Thermal Science 2009年第3期18卷 268-275页

作者： Mustapha FARAJI Hamid EL QARnIA EI khadir LAKHAL Fluids Mechanic and Energetic Laboratory Automatic Environment and Transfer Process Laboratory Cadi Ayyad University Faculty of Sciences Semlalia Department of Physics

This work aims to numerically study the melting natural convection in a rectangular enclosure heated by three discreet protruding electronic chips. The beat sources generate heat at a constant and uniform volumetric rate. A part of the power generated in the heat sources is dissipated to a phase change material （PCM, n-eicosane with melting temperature, Tm = 36℃）. numerical investigations were carded out in order to examine the effects of the plate thickness on the maximum temperature of electronic components, the percentage contribution of plate heat conduction on the total removed heat and temperature profiles in the plate. Con＇elations for the dimensionless secured working time （time to reach the threshold temperature, Tcr = 75℃） and the corresponding liquid fraction were derived.

关键词： Phase change material protruding electronic component natural convection

Achieving Optical Fiber Communication Experiments by Optisystem

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Achieving Optical Fiber Communication Experiments by Optisys...

作者： Alla Abbas khadir 湖南大学

学位级别：硕士

光纤通信技术是当前通信中最重要的技术之一,它可以通过光纤将传输加载在光上的信息。目前,光纤通信取得了巨大的进步,一些新技术大大的提高了通信容量,使得光通信向更广的领域应用。光通信的发展由于成本和重构设备的限制使得很多先进... 详细信息

光纤通信技术是当前通信中最重要的技术之一,它可以通过光纤将传输加载在光上的信息。目前,光纤通信取得了巨大的进步,一些新技术大大的提高了通信容量,使得光通信向更广的领域应用。光通信的发展由于成本和重构设备的限制使得很多先进的光通信技术在某种程度上不能广泛被很快的应用,因此对于系统的实验与仿真对于预测和优化系统性能是十分必要的。本文利用光系统(Optisystem)软件中的分析各种光通信技术(如WDM, DBM, EDFA和DCF等)。可以发现,利用此软件可以实现前面所提到的每个技术的基本功能。此软件还可以通过调整适当的光通信中的可理解的范围的机制参数来减低系统成本,使得学生可以更加快速直观的理解光通信系统。本文分为6章,第一章主要介绍了光通信的基本历史,以及回顾了光纤通信的发展和重要性。并介绍了Optisystem软件的相关工作和本文的组成结构。第二章主要介绍了复用技术的总类,在本文我们主要介绍了两种复用技术。目前,普遍应用的SDH技术采用的是电域的时分复用。时分复用扩容的优点是扩容的策略很明显,可以实现4倍的无缝平滑升级,已达到更高的速率,并且容易在数据流中抽取某个数据和组合信号,适合在需要采取保护策略的环路网络中使用,但是由于高速电子器件和半导体激光器的直接调制能力的限制,要实现40Gb/s以上的信号速率十分困难,而光时分复用技术的出现为解决电子瓶颈问题提供了有效的措施。光时分复用是一种构成高比特率传输很有效的技术,在系统发送端与接收端,与信号处理有关的所有电子设备均工作在基带比特速率下,不存在电子瓶颈问题,采用光学复用方式把低比特率数据流进行复用,经过光纤传输后,在接收端用光学方法把它们解复用出来,这种方法避免了使用高速电子器件。另一种复用技术就是光波分复用技术把光纤可能应用的波长范围划分成若干个波段,每个波段用作一个独立的通道传输一种预订波长的光信号,在波分复用传输系统的发送端,多路信号经光／电转化由不同波长的光载波携带,再采用合波器将多个载波信号进行复接,对于100公里以上的传输距离,通常还需要加光放大器补偿线路造成的光功率损耗;而在接收端采用分波器分离出不同波长光信号,再经过光／电转换恢复出原始电信号送到相应的接收机。第三章主要介绍了光调制技术,根据高的频谱利用率的调制码型来提高系统性能。本章将重点介绍几种普遍实用的调制码型。非归零码是最简单的调制码型,其一个脉冲代表一个完整的比特周期,其具有窄的光谱,对激光相位噪声不敏感,并对发送机与接收机有较窄的电带宽,简化了发送与接收的复杂度。第二种码型是载波抑制的归零码,这是归零码得一种特殊形式,其载波抑制,而且相邻比特之间有相位转移,这种格式可以很好的抑制四波混频效应和群速度色散。第三种码型是差分相移键控,这种调制格式将信息采用相位编码的格式取代幅度编码。由于光电二极管对光强度很敏感,而对光相位并不敏感,因此,差分相移键控信号在接收端需要特殊的接收机,如马赫-曾德尔时延干涉仪。这种信号可以较好的抑制光纤的非线性和偏振模色散效应,增加传输距离。最后我们将介绍双二进制编码,其是将传统的振幅键控和相移键控结合起来,这种调制格式当每个相位转变时,有奇数个0比特在两个连续的1比特之间出现,发送端采用电信号的前置编码来避免在接收端的循环解码,从而使得接收机可以采用类似非归零码得标准直接检测。这种调制格式可以很好的抑制自发布里渊散射。本章最后,我们利用optisystem模型实现了双二进制编码的系统。第四章介绍了几种放大器,包括以下几种：第一种介绍了半导体光放大器,这是一种增益介质,可以分为法布里-珀罗半导体激光放大器和半导体行波光放大器两种。第二种式拉曼放大器,它是基于自发拉曼散射非线性效应来实现的,这种效应的产生是由于光纤中的高功率所引起的。拉曼放大的主要特征是沿着光纤传输可以实现连续放大。双向放大并且可以提供稳定性,对反射不敏感等特性。第三种是布里渊光纤放大器,它和拉曼放大器除了是利用自发布里渊散射非线性效应实现外其他都是相同的。这种放大器可以通过放大某个信道而不影响其他信道来实现信道选择性放大。第四种是掺饵光纤放大器,它是利用饵元素来实现放大过程的。它可以提供两个放大窗口,分别是980nm和1550nm。最后我们模拟搭建了利用掺饵光纤放大器optisystem系统并发现信号的放大特性。而且噪声较小,放大前后没有明显差别。第五章我们主要介绍了色散补偿器件,由于色散造成的脉冲展宽会限制信号的全光传输距离,因此为了延长全光传输距离,需采用色散补偿技术。光纤通信系统及技术的发展要求色散补偿技术向着高补偿效率,结构简单,高可靠性,使用方便,易于升级和扩容、器件小型化,降低成本等方向发展。我们这里将介绍几种色散补偿方法来克服光纤中的色散引起的衰

关键词：光通信技术 Opti system软件波分复用色散补偿掺铒光纤放大器

Composition and antimicrobial activity of Cistus munbyi essential oil: an endemic plant from Algeria

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Journal of Forestry Research 2017年第6期28卷 1127-1132页

作者： Fethi Benbelaid Abdelmounaim khadir Mourad Bendahou Mohamed Amine Abdoune Alain Muselli Jean Costa Laboratory of Applied Microbiology in Food Biomedical and Environment Aboubekr Belkad UniversityP.O. Box 119 13000 Tlemcen Algeria Department of Biology University of Oran 1 Ahmed Ben Bella Es Senia Oran Algeria Laboratory of natural Products Chemistry University of Corsica UMR CNRS 6134 Campus Grimaldi BP 5220250 Corte France Department of Biology Faculty of Sciences of Nature LifeEarth and Universe Aboubekr Belkad UniversityP.O. Box 119 13000 Tlemcen Algeria

The chemical composition and antimicrobial potential of Cistus munbyi essential oil were studied for the first time. GC and GC–MS analysis revealed 48 compounds representing 96.98% of the oil. Terpinen-4-ol(23.75%), meta-Cymene(17.30%), and Sabinene(12.38%)were the major constituents. Antimicrobial activity was evaluated against nine pathogens using the disc diffusion and broth micro-dilution methods. Results show that *** essential oil possesses strong antimicrobial activity against all strains, regardless if Gram-positive or Gramnegative bacteria, or yeast, with MICs values not exceeding10(mg/ml). In addition to its efficacy, C. munbyi essential oil has an unusual antimicrobial potency which is attributed to its specific chemical composition. Thus, findings presented here suggest that endemic C. munbyi contains a very interesting essential oil that may be valuable in several areas.

关键词： Antimicrobial activity Chemical composition Cistus munbyi Essential oil