Tagne Kamdem H.T.,University of Dschang
Journal of Thermal Science and Engineering Applications | Year: 2017
This paper proposed radiative characteristics' expressions for media containing randomly oriented fibers in space. In deriving these simple radiative characteristics' expressions, the fibrous medium effective extinction coefficient is defined to match with the one of large particle obtained by combining geometric optics and Fraunhofer diffraction theory. Fibrous media radiative characteristics are then derived as an average over all incident radiation angles of single fiber radiative characteristics. Theoretical hemispherical reflectance and normal transmittance predictions using the proposed fibrous media radiative characteristics based on the Mie theory agreed well with literature experiments. Therefore, media containing fiber randomly oriented in space can be scaled to a suitable equivalent media such that scattering mechanisms behave similarly to that occurring in a participating media containing spherical particles. Numerical investigations show that a theoretical model which assumes Henyey-Greenstein (HG) scattering phase function can conveniently be used for the estimation of equivalent fibrous media radiative characteristics using hemispherical reflectance measurements. On the other hand, the estimated equivalent fibrous media radiative characteristics from hemispherical measurements and using a two-flux model with isotropic scaling radiative characteristics may be subjected to serious errors in the case of semitransparent media for which the absorption is significant. © 2017 by ASME.
Agency: European Commission | Branch: FP7 | Program: CP-FP-SICA | Phase: SSH.2011.4.1-2 | Award Amount: 3.50M | Year: 2012
The overall objective of the African Rural-City Connections (RurbanAfrica) project is to explore the connections between rural transformations, mobility, and urbanization processes and analyze how these contribute to an understanding of the scale, nature and location of poverty in sub-Saharan Africa. The RurbanAfrica project will advance the research agenda on rural-city connections in sub-Saharan Africa by addressing a range of crucial components: agricultural transformations, rural livelihoods, city dynamics, and access to services in cities. In this respect the project will challenge a number of generally accepted truths about rural and city development, and the importance and implication of migration in shaping these. It will thereby question the overall negative interpretations of the economic role of rural-urban mobility and migration in sub-Saharan Africa and generate new insights into the relationship between rural-city connections and poverty dynamics. The project will include nine partners; four European, one international, and four sub-Saharan African. RurbanAfrica focuses on four country cases: Rwanda, Tanzania, Cameroon and Ghana and examine in-depth two rural-city connections in each of the case countries. Research is organized into six work packages: Agricultural transformation, rural livelihoods, city dynamics, access to services, knowledge platform and policy dialogue, and synthesis, dissemination and management. Central to the approach is the on-going integration of policy research, policy dialogue, knowledge sharing and empirical research. Through ongoing collaboration between senior and junior researchers from European and sub-Saharan African partners, and co-supervising of PhD students, the project will contribute to capacity building and potentially impact curriculum development. The research and dissemination process will be supported by a scientific advisory board, with members from European and sub-Saharan African research institutions.
Sobze Sanou M.,University of Dschang
Igiene e sanità pubblica | Year: 2013
With the decreasing HIV epidemiology in Cameroon (5.5% in 2004 to 4.3% in 2011), HIV/AIDS remains a major public health concern, affecting mostly the sexually active population, among which the young University students represent an important target. Since sexual intercourses represent about 90% of HIV transmission, understanding the sexual behaviors of youth could relevantly optimize the design of HIV prevention strategies, through updated and adapted communication strategies for healthy sexual behavioral changes. A qualitative, descriptive and cross-sectional study was conducted in November 2010, among 518 newly registered students in the various faculties of the University of Dschang, Cameroon. In order to evaluate Knowledge, Attitudes and Practices (KAP) toward HIV/AIDS prevention among the study participants, a structured questionnaire was administered to each participant, on the basic knowledge about HIV/AIDS and condoms. Data analysis was performed using Epi Info version 3.5.0 software. The mean age of participants was 20 years, with a slight female predominance (52%). 98.6% of students voted familiar with the theme "condom", with 88.9% giving a satisfactory definition. However, 41.1% do not know the appropriate transmission route of HIV, while 5.4% do not master the correct use of condom; with up to 75.7% being aware of the female condom existence. Although 97.8% of students consider the proper use of condoms as an effective HIV preventive tool, up to 34.5% of them fail to use condoms during sexual intercourses and 69% were not in favor of the use of female condom, mainly due to a decreasing sexual pleasure. Despite the existing sensitization campaigns, the perception of condoms is still very poor among young Cameroonian academics; with the non-systematic use of condoms being the major setback. The lack of familiarity to female condom, both among female and male, would also be a contributing drawback. These major sexual behavioral risk factors to HIV infection appear as key points to address during the campaigns to ensure owning of healthy sexual habits, a leading component to reduce HIV incidence among young Cameroonian/Africans.
Kuete V.,University of Dschang
Toxicological Survey of African Medicinal Plants | Year: 2014
Toxicological Survey of African Medicinal Plants provides a detailed overview of toxicological studies relating to traditionally used medicinal plants in Africa, with special emphasis on the methodologies and tools used for data collection and interpretation. The book considers the physical parameters of these plants and their effect upon various areas of the body and human health, including chapters dedicated to genotoxicity, hepatotoxicity, nephrotoxicity, cardiotoxicity, neurotoxicity, and specific organs and systems. Following this discussion of the effects of medicinal plants is a critical review of the guidelines and methods in use for toxicological research as well as the state of toxicology studies in Africa. With up-to-date research provided by a team of experts, Toxicological Survey of African Medicinal Plants is an invaluable resource for researchers and students involved in pharmacology, toxicology, phytochemistry, medicine, pharmacognosy, and pharmaceutical biology. • Offers a critical review of the methods used in toxicological survey of medicinal plants • Provides up-to-date toxicological data on African medicinal plants and families • Serves as a resource tool for students and scientists in the various areas of toxicology. © 2014 Elsevier Inc. All rights reserved.
Svanstedt N.,Gothenburg University |
Woukeng J.L.,University of Dschang
Nonlinear Analysis: Real World Applications | Year: 2013
Homogenization of Wilson-Cowan type of nonlocal neural field models is investigated. Motivated by the presence of a convolution term in this type of models, we first prove some general convergence results related to convolution sequences. We then apply these results to the homogenization problem of the Wilson-Cowan-type model in a general deterministic setting. Key ingredients in this study are the notion of algebras with mean value and the related concept of sigma-convergence. © 2012 Elsevier Ltd. All rights reserved.
Kamdem H.T.T.,University of Dschang
Journal of Thermophysics and Heat Transfer | Year: 2015
Ray effects through two- and three-dimensional isotropically scattering, participating media are investigated using four ordinates methods: discrete ordinates, using a classical quadrature scheme and a refined azimuthal discretization around the azimuthal angle endpoints; and finite volume, with and without refined azimuthal discretization around the azimuthal angle endpoints. The discrete ordinates method with refined azimuthal angular discretization consists of a coupling of Gaussian quadrature for polar discretization and control azimuthal angle discretization splitting into a quadruple range. For both the discrete ordinates method with refined azimuthal angular discretization and the finite volume method with refined azimuthal angular discretization, the azimuthal direction is discretized such that azimuthal grid points are close to the azimuthal angle endpoints. Radiative heat transfer through isotropically scattering, participating and optically thin media within enclosures considering uniform and strip diffuse boundary conditions is considered. Excellent agreement between the discrete ordinates method/finite volume method with refined azimuthal angular discretization and the benchmark literature resultsisachieved for high-order azimuthal discretization, whereas finer high-order azimuthal discretization is required for the finite volume method. Ray effects are eliminated for combinations of higher-order azimuthal discretization and refined azimuthal discretization around the azimuthal angle endpoints. It has also been found that, in order to eliminate ray effects, the discrete ordinates and finite volume methods' quadrature sets' order must be increased as the medium's aspect ratio decreases or when the size of the diffuse strip of incident radiation on one of the medium's surfaces is decreased. © 2012 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.
Simo G.,University of Dschang |
Rayaisse J.B.,CIRDES Center International Of Recherche Développement Sur L'elevage En Zone Sub Humide
Parasites and Vectors | Year: 2015
African trypanosomiases are infectious diseases caused by trypanosomes. African animal trypanosomiasis (AAT) remains an important threat for livestock production in some affected areas whereas human African trypanosomiasis (HAT) is targeted for elimination in 2020. In West and Central Africa, it has been shown that the parasites causing these diseases can coexist in the same tsetse fly or the same animal. In such complex settings, the control of these diseases must be put in the general context of trypanosomiasis control or "one health" concept where the coordination of control operations will be beneficial for both diseases. In this context, implementing control activities on AAT will help to sustain HAT control. It will also have a positive impact on animal health and economic development of the regions. The training of inhabitants on how to implement and sustain vector control tools will enable a long-term sustainability of control operations that will lead to the elimination of HAT and AAT. © 2015 Simo and Rayaisse.
Ngouateu Wouagfack P.A.,University of Dschang |
Tchinda R.,University of Dschang
Renewable and Sustainable Energy Reviews | Year: 2013
This paper presents a literature review of the optimization of absorption refrigeration systems based on finite-time thermodynamics. An overview of the various objective functions is presented. © 2012 Elsevier Ltd.
Ngouateu Wouagfack P.A.,University of Dschang |
Tchinda R.,University of Dschang
International Journal of Refrigeration | Year: 2011
This paper presents an optimization study of an irreversible refrigeration absorption system based on a new thermo-ecological criterion. The considered objective function is the ecological coefficient of performance (ECOP). It takes into account the first and second law of thermodynamics and is defined as the cooling load per unit loss rate of availability. The ecological coefficient of performance has been expressed and maximized according to the temperatures of the working fluid in the main components of the system. The corresponding optimal temperatures and other optimum performance parameters have been derived analytically, and the effects of the internal irreversibility, the heat leakage coefficient and the source temperature ratio on the global and optimal performances are discussed. The results show that the maximum coefficient of performance (COP) and ecological coefficient of performance (ECOP) occurs for the same operating conditions. © 2010 Elsevier Ltd and IIR. All rights reserved.
Kuete V.,University of Dschang
Planta Medica | Year: 2010
In Cameroon, infectious diseases are amongst the most commonly notified diseases and largest cause of mortality. Many plants are used locally in traditional medicine for their treatment. The aim of the present review is to summarize currently available evidence and knowledge concerning Cameroonian plants used to treat bacterial and fungal infections, and the efficacy of plant-derived extracts and compounds. The traditional uses of plants in the treatment of infectious diseases have been collected and tabulated. The antimicrobial activity of the extracts and the chemical constituents of most of these plants are summarized in this report. Plants used traditionally in Cameroonian medicine, with laboratory work on any part or products, have been documented. Numerous extracts and compounds have been tested for antimycobacterial, antibacterial and antifungal efficacy and some of them were significantly active. Most of the bioactive compounds isolated were phenolics and alkaloids. In conclusion, many plant species are used in traditional medicine in Cameroon to treat infectious diseases, and several interesting openings have originated for further inquiry following in vitro antimicrobial activity evaluation. However, much work is still to be done to standardize methods and cut-off points for describing the antimicrobial activity, and on the study of the mechanisms of action. © Georg Thieme Verlag KG Stuttgart New York.