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Performance Evaluation of Solar Chimney Draft: Application to Ventilation

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Smart Grid and Renewable Energy 2024年第4期15卷 107-122页

作者： Boukaré Ouedraogo Adama Ouedraogo Arouna Kabore Kalifa palm.Dieudonné Joseph Bahiebo Laboratoire dEnergies Thermiques Renouvelables (LETRE) Universit Joseph KI-ZERBO: UFR/SEA Ouagadougou Burkina Faso Laboratoire de Chimie Analytique Physique Spatiale et Energtique (LACAPSE) Universit Norbert ZONGO Koudougou Burkina Faso Centre Universitaire Polytechnique de Kaya (CUP-Kaya) Universit Joseph KI-ZERBO Ouagadougou Burkina Faso Laboratoire des Systmes dEnergie Renouvelable et Environnement Institut de Recherche en Sciences Appliques et Technologies (IRSAT) Centre National de la Recherche Scientifique et Technologique (CNRST) Ouagadougou Burkina Faso

Ventilation is one of the factors contributing to energy consumption in buildings and food preservation. The solar chimney proves to be an alternative for reducing conventional energy consumption. Thus, in this study, the performance of a solar chimney with two active faces for thermally drawing air from a chamber for preserving agri-food products was evaluated. These performances were experimentally assessed through data measurements: temperatures and velocities within the chimney, and their analysis using Excel and MATLAB. The obtained results were compared with those from literature to verify their validity. From this study, it is found that the maximum temperature at the chimney outlet reaches 49.4˚C with an average value of 43.7˚C. Additionally, the heating evolution of the chimney air presents four (04) identical phases in pairs, reflecting the chimney’s operation throughout day. The temperature difference between the outlet and inlet of the chimney reaches a maximum of 17˚C with an average of 12.6˚C. Regarding airflow, the maximum air velocity at the chimney outlet is 0.8 m/s, and the average velocities have consistently been greater than or equal to 0.46 m/s. Thus, it can be concluded that the solar chimney is capable of providing ventilation for the preservation chamber through thermal draft.

关键词： Solar Chimney Natural Ventilation Thermal Draft Airflow Chimney Effect

Improvement of Mechanical Qualities of Clay Material through Coconut Fiber Stabilization

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Materials Sciences and Applications 2024年第7期15卷 201-212页

作者： Boukaré Ouedraogo Abdoulaye Compaore Moumouni Derra Kalifa palm.Dieudonné Joseph Bahiebo Laboratoire dEnergies Thermiques Renouvelables (LETRE) Universit Joseph KI-ZERBO Ouagadougou Burkina Faso Laboratoire Chimie Analytique de Physique Spatiale et Energtique Universit Norbert ZONGO Koudougou Burkina Faso Institute de Recherche en Sciences Appliques et Technologies (IRSAT/CNRST) Ouagadougou Burkina Faso Laboratoire de Matriaux et Environnement (LAME) Universit Joseph KI-ZERBO Ouagadougou Burkina Faso

The criticisms regularly formulated towards clay or soil, in general, are its weak mechanical qualities and low water quality. Therefore, it is necessary to find techniques to improve the properties of this material, which is widely used worldwide. Here, we propose stabilizing clay with coconut fiber as a solution to enhance its mechanical properties. To do this, we used an experimental method, first determining the geotechnical properties of the clay and then its mechanical properties. The geotechnical study using the Proctor Test revealed that the dry density of the clay is γb = 1.42 g/cm3, and its water content is W = 22.3%. By applying the rolling method, the Atterberg limits were determined: liquid limit Wl = 63.6, plastic limit Wp = 27.9, plasticity index Ip = 35.7, and consistency index Ic = 1.46. With 25 P = 35.7 1.3, according to the water classification, it falls into class A3ts. The mechanical part focused on compression and flexural strengths obtained using a PROETI hydraulic press. We obtained a flexural strength of 0.63 MPa for simple clay (BA);0.89 MPa for clay + 0.25% fiber (BAF1/4);1.68 MPa for clay + 0.5% fiber (BAF1/2);1.87 MPa for clay + 0.75% fiber (BAF3/4);and 3.91 MPa for clay + 1% fiber (BAF1). As for the compression strength, BA = 5.90 MPa, BAF1/4 = 6.395 MPa, BAF1/2 = 6.292 MPa, BAF3/4 = 6.065 MPa, and BAF1 = 5.423 MPa. The addition of fiber has thus improved the mechanical qualities of the simple clay. These stabilized bricks can be used for sustainable and bioclimatic construction, providing higher durability and good comfort.

关键词： Compression Strength Flexural Strength Coconut Fiber Clay Geotechnical Properties

Experimental Study of the Thermal Behavior of a Bioclimatic Building Prototype in a Sahelian Zone

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Smart Grid and Renewable Energy 2024年第8期15卷 187-199页

作者： Arouna Kaboré Boukaré Ouédraogo Sayouba Sandwidi Vincent Zoma Hermann Kaboré Kalifa palm Laboratoire des Energies Thermiques et Renouvelables (LETRE) Universit Joseph KI-ZERBO Ouagadougou Burkina Faso Laboratoire de Chimie Analytique Physique Spatiale et Energtique (LACAPSE) Universit Norbert ZONGO Koudougou Burkina Faso Laboratoire de Physique et Chimie de lEnvironnement Universit Joseph KI-ZERBO Ouagadougou Burkina Faso Laboratoire des Systmes dEnergie Renouvelable et Environnement Institut de Recherche en Sciences Appliques et Technologies (IRSAT) Centre National de la Recherche Scientifique et Technologique (CNRST) Ouagadougou Burkina Faso

Buildings constructed with modern materials (cement blocks, sheet metal, reinforced concrete, etc.) in the Sahelian zone often generate excessive electricity consumption and consequently very high electricity bills. This study is a contribution to the development of new building types based on the principle of bioclimatic construction. The aim is to find materials suited to the Sahelian climate and improve thermal comfort. To this end, an experimental study of the hygrothermal behavior of a bioclimatic building prototype with a domed roof is being carried out. Site meteorological data, air temperature and relative humidity of the building’s internal environment were measured for three climatic seasons in Burkina Faso. The data acquisition system consists of thermocouples, solarimeters and humidity meters, and the data are processed using Excel and Origin Pro software. The results show that, despite the high temperature values (between 36˚C and 39˚C) of the internal environment measured in the hot season, good thermal performance is achieved, in particular an average phase shift of 7.17 h and an average damping of 10.81˚C. The dome-roofed building could therefore contribute to limiting heat transmission to the building interior, improving thermal comfort all year round. Analysis of humidity profiles shows that indoor humidity varies between 66% and 80% for the September period, and between 44% and 69% for the January period. The high values of internal ambient humidity could be reduced by very good ventilation of the building. This study shows that the proposed bioclimatic building prototype with domed roof could be integrated into the Sahelian habitat.

关键词： Thermal Comfort Hygrothermal Behavior Bioclimatic Building Thermal Inertia Domed Roof

Mesoscience in cell biology and cancer research

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Cancer Innovation 2022年第4期1卷 271-284页

作者： Haili Qian Adriana sujey Beltran State Key Laboratory of Molecular Oncology National Cancer Center/National Clinical Research Center for Cancer/Cancer HospitalChinese Academy of Medical Sciences and Peking Union Medical CollegeBeijingChina Department of Pharmacology University of North Carolina at Chapel HillChapel HillNCUSA

Mesoscale characteristics and their interdimensional correlation are the focus of contemporary interdisciplinary *** is a discipline that has the potential to radically update the existing knowledge structure,which differs from the conventional unit-scale and system-scale research models,revealing a previously untouchable area for scientific *** biology research aims to dissect the complex problems of life systems by conducting comprehensive research and integrating various disciplines from all biological levels of the living ***,the mesoscientific issues between different research units are neglected and *** research in biology requires the integration of research theories and methods from other disciplines(mathematics,physics,engineering,and even visual imaging)to investigate theoretical and frontier questions of biological processes through experiments,computations,and *** reviewed integrative paradigms and methods for the biological mesoscale problems(focusing on oncology research)and prospected the potential of their multiple dimensions and upcoming *** expect to establish an interactive and collaborative theoretical platform for further expanding the depth and width of our understanding on the nature of biology.

关键词： mesoscience biology paradigms oncology integrative paradigms

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20／30GHz卫星个人通信网（下）

电信快报 1993年第8期 15-18页

作者： palm.,LC

Heat Transfer and Fluid Flow of Nanofluids in Laminar Radial Flow Cooling Systems

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Journal of Thermal Science 2005年第4期14卷 362-367页

作者： Gilles ROY Samy Joseph palm.Cong Tam NGUYEN Faculty of Engineering Universite de MonctonMonctonNBCanadaElA 3E9

Nanofluids are considered as interesting alternatives to conventional coolants. It is well known that traditional fluids have limited heat transfer capabilities when compared to common metals. It is therefore quite conceivable that a small amount of extremely fine metallic particles placed in suspension in traditional fluids will considerably increase their heat transfer performances. A numerical investigation into the heat transfer enhancement capabilities of coolants with suspended metallic nanoparticles inside a radial, laminar flow cooling configuration is presented. Temperature dependant nanofluid properties are evaluated from experimental data available in recent literature. Results indicate that considerable heat transfer increases are possible with the use of relatively small volume fractions of nanoparticles. Generally, however, these are accompanied by considerable increases in wall shear-stress. Results also show that predictions obtained with temperature variable nanofluid properties yield greater heat transfer capabilities and lower wall shear stresses when compared to predictions using constant properties.

关键词： nanofluids nanoparticles heat transfer laminar flow confined radial flow.

Study of the behaviour of the dielectric constant in Cu,Fe:BaTiO_3

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2008年第3期9卷 429-434页

作者： Alioune OUEDRAOGO Kalifa palm.Issaka OUEDRAOGO Guy CHANUSSOT Laboratory of Applied Organic Chemistry and Physics UFR/SEA University of Ouagadougou BP 7021 Ouagadougou Burkina Faso Laboratory of Dielectrics University of Dijon 21000 Dijon France)

In this work we study the behaviour of the dielectric constant of BaTiO3 single crystals doped with Cu and Fe for different ion percentages, particularly, the influence of these hetemvalent substitutions on the ferroelectric-paraelectric phase transition whose temperature is found at Tc=120℃ for pure samples. The dielectric constant e in terms of temperature shows that the Curie temperature decreases when the quantity of impurities increases and presents a broadening and flattering of the maximum oft（T） within higher values, with the transition becoming more and more diffuse. It is interesting to have a material with very high permittivity （high-k） because of its capacity to store an important quantity of electric charges. The t anisotropy and the Curie-Weiss law are also verified with a good ratio between the slopes ofε^-l（T） from both sides of the transition, leading to a Curie constant： C= 13 × 10^4 K for BaTiO3：1.6%Fe in the polar phase. BaTiO3 is a displacive ferroelectric going through a first-order phase transition. The substitutions have an effect on the dynamics of the perovskite lattice. They induce charges transfer to Ti and a diminution of elastic forces in BaTiO3. Then we discuss the transition but on the nature of the material. fact that the maximum of permittivity does not depend on the phase

关键词： Phase transition Ferroelectric BaTiO3 Remeika single crystals Dielectric constant Curie constant