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Two-Stream Approximation to the Radiative Transfer Equation:A New Improvement and Comparative Accuracy with Existing Methods

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Advances in Atmospheric Sciences 2024年第2期41卷 278-292页

作者： f.momo temgoua L.Akana NGUIMDO DNJOMO Environmental Energy Technologies Laboratory(EETL) Faculty of SciencesUniversity of YaoundéPO Box 812 YaoundéCameroon Department of Electrical and Electronic Engineering Faculty of Engineering and TechnologyUniversity of BueaPO Box 63 BueaCameroon

Mathematical modeling of the interaction between solar radiation and the Earth's atmosphere is formalized by the radiative transfer equation(RTE), whose resolution calls for two-stream approximations among other methods. This paper proposes a new two-stream approximation of the RTE with the development of the phase function and the intensity into a third-order series of Legendre polynomials. This new approach, which adds one more term in the expression of the intensity and the phase function, allows in the conditions of a plane parallel atmosphere a new mathematical formulation of γparameters. It is then compared to the Eddington, Hemispheric Constant, Quadrature, Combined Delta function and Modified Eddington, and second-order approximation methods with reference to the Discrete Ordinate(Disort) method(δ –128 streams), considered as the most precise. This work also determines the conversion function of the proposed New Method using the fundamental definition of two-stream approximation(f-TSA) developed in a previous work. Notably,New Method has generally better precision compared to the second-order approximation and Hemispheric Constant methods. Compared to the Quadrature and Eddington methods, New Method shows very good precision for wide domains of the zenith angle μ 0, but tends to deviate from the Disort method with the zenith angle, especially for high values of optical thickness. In spite of this divergence in reflectance for high values of optical thickness, very strong correlation with the Disort method(R ≈ 1) was obtained for most cases of optical thickness in this study. An analysis of the Legendre polynomial series for simple functions shows that the high precision is due to the fact that the approximated functions ameliorate the accuracy when the order of approximation increases, although it has been proven that there is a limit order depending on the function from which the precision is lost. This observation indicates that increasing the order of app

关键词： Radiative Transfer Equation two-stream method Legendre polynomial optical thickness moments of specific intensity conversion function transmittance reflectance

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Hydro-geochemistry of groundwater and surface water in Dschang town(West Cameroon):Alkali and alkaline-earth elements ascertain lithological and anthropogenic constraints

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Journal of Groundwater Science and Engineering 2021年第3期9卷 212-224页

作者： Yemeli Elida Joelle temgoua Emile Kengni Lucas Ambrosi Jean-Paul momo-nouazi Mathieu Silatsa-Tedou francis Brice Wamba franck Robean Tchakam-Kamtchueng Brice University of Dschang Department of Earth SciencesDschangCameroon. University of Dschang Faculty of Agronomy and Agricultural SciencesDschangCameroon. Aix Marseille University CNRSIRDINRAECollege de FranceCEREGEAix En ProvenceFrance. Institute of Geological and Mining Research YaoundeCameroon.

The study aims to identify a suitable site for open and bore well in a farmhouseusing ground magnetic survey in south *** also aims to define depth to granitoid and structural elements which traverse the selected *** data(n=84)measured,processed and interpreted as qualitative and *** results of total magnetic intensities indicate that the area is composed of linear magnetic lows trending NE-SW direction and circular to semi-circular causative *** magnetic values ranged from-137 nT to 2345 nT with a mean of 465 *** to equator shows significant shifting of causative bodies in the southern and northern *** signal map shows exact boundary of granitic *** directional filter has brought out structural element trending NE-SW *** of individual profile brought to light structurally weak zone between 90 m and 100 m in all the profile *** decrease of magnetic values from 2042 nT to 126 nT noticed in profile line 6 between 20 m and 30 m indicates fault *** breaks obtained from these maps were visualized,interpreted and identified two suitable sites for open and bore *** averaged power spectrum estimates depth of shallow and deep sources in 5 m and 50 m,*** method has also been applied to estimate depth of granitoid and structural elements using structural indexes 0,1,2,and 3 and found depth ranges from90 *** indicates magnetic method is one of the geophysical methods suitable for groundwater exploration and site selection for open and borewells.

关键词： Alkali/alkaline-earth elements Groundwater and surface water Geochemical anomaly Anthropogenic impact Dschang-Cameroon

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Spatio-Temporal Dynamic of Land Use and Land Cover in the Classified forest of Djoli-Kera, South-Eastern, Chad

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Open Journal of forestry 2018年第3期8卷 283-296页

作者： Lucie félicité temgoua Behimnan Allaissem Martin Tchamba Goy Saradoum Mbaiakambeye Mbaidje Osée Marie Caroline momo Solefack Department of forestry Faculty of Agronomy and Agricultural Sciences University of Dschang Dschang Cameroon Department of Biology University Institute of Agricultural Sciences and Environment Sarh Chad Department of Plant Biology Faculty of Science University of Dschang Dschang Cameroon

This study was carried out in the classified forest of Djoli-Kera found in the South-Eastern part of Chad. It aimed to analyze the spatial and temporal dy-namics of land cover between 1972 and 2013 and to determine the drivers of vegetation degradation. The databases used were made up of 4 Landsat satellite images (1MSS of 1972, 5TM of 1984, 7ETM+ of 1990 and 2010) and a spot 6 image of 2013, supplemented by field studies. Satellite images were processed using ENVI and ArcGIS software. Interview was used to identify the activities carried out by the local population. In 1972, the classified forest consisted of four types of land cover, the most important of which was open forest (51%), followed by wooded savannah (26%), tree savannah (21%) and sparse vegetation consisting of farms and fallows (2%). Gradually open forest and tree savannah disappeared. In 2013, the main types of land cover were shrub savannah (40%), sparse vegetation (28%), wooded savannah (12%), bare soil (12%) and dwellings (8%). Livestock, agriculture, wood collection and bushfires are perceived by local population as main drivers of forest cover change. Awareness-raising, monitoring and regulation of access to resources must be pursued, but also managers of the classified forest must accompany the local populations in the planting of trees and the setting up of more efficient farming systems to reduce pressure on the forest’s resources.

关键词： Land-Use Land-Cover Satellite Images Degradation Chad

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Typology and Agroecology of Agroecosystems in Vegetation Dynamics in the Ecotones of the Mbam and Inoubou

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Open Journal of forestry 2024年第1期14卷 42-66页

作者： Alex Bruno Dong Etchike Lucie félicité temgoua Bertine Tiokeng Marie Caroline momo Solefack Martin Benoit Ngassoum Pierre Marie Mapongmetsem Laboratory of Applied Botany Faculty of Sciences of the University of Dschang Dschang Cameroon Department of forestry Faculty of Agronomy and Agricultural Sciences University of Dschang Dschang Cameroon National School of Agro-Industrial Sciences of the University of Ngaoundéré Ngaoundéré Cameroon Laboratory of Biodiversity and Sustainable Development of the University of Ngaoundéré Ngaoundéré Cameroon

Agroforestry systems strongly characterize the Cameroonian agrarian landscape. Agroforests are among those structuring the ecotones of Mbam and Inoubou in the Central Cameroon region. Numerous works on agroecosystems of Central and South Cameroon, few have come out contribution of the structure of these traditional systems in the dynamics of the vegetation of these forest-savannah ecotones. The present contribution has the overall objective of demonstrating the structural efficiency of agroforests the dynamics of ecotone vegetation, but also in the conservation of biodiversity. To do this, a participatory analysis was carried out with 56 farmers distributed in the five villages of Makénéné. Botanical inventories supplemented socio-economic household surveys. The data collected was subjected to various analyzes (univariate test, analysis of variance, multivariate test, PCA, CAH). The results reveal that 55.2% of agroforests are less than 15 years old and those with an area greater than 1500 m2 predominate (33%). They are mainly young with generally small surface areas. The horizontal structure reveals that the largest diameter classes are those of [20 - 30 cm[ and [10 - 20 cm[ with a very low rate of basal area. Agroforests with trees over 10 m high are dominant in five villages of Makénéné. Two types of structural profiles characterize the agroforestry flora of the area, namely intensive pluristratified home gardens on savannah and intensive pluristratified agroforests under forest-savannah transition vegetation. Principal Component Analysis (PCA) and Ascending Hierarchical Clustering (HAC) show three Agroforest Clusters each. The PCA distribution reveals that woody biomass (Y) is strongly correlated with tree diameter (DBH) and significantly with height (Cluster 2). The age (AAG) (Cluster 1) of these agroforests, on the other hand, remains independent of the density (DST) of these trees (Cluster 3). The agroforests in the Nyokon, Carrière and Mocksud vil

关键词： Agroforests Agroecosystem Center Cameroon Dynamics Agroecology Typology

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Soil Organic Carbon and Nitrogen Dynamics in Arabica Coffee Agroforestry Systems in the Noun Division, West Cameroon

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Open Journal of forestry 2023年第3期13卷 262-277页

作者： Abdel Malik Atoupka Emile temgoua Lucie félicité temgoua Jean Baurel Atchombou Steve Tassiamba faculty of Agronomy and Agricultural Sciences University of Dschang Dschang Cameroon

Agroforestry systems (AfSs) offer viable solutions to climate change because of the below-ground biomass (BGB) that is maintained by the soil. Therefore, spatially explicit estimation of their BGB is crucial to account for emission reduction efforts. A study to assess soil organic carbon (SOC) and nitrogen dynamics in Arabica coffee agroforests was conducted in two subdivisions (foumbot and Kouoptamo) of the Noun Division in western Cameroon. The methodological approach involved the collection of 150 soil samples taken at different depths: 0 - 10, 10 - 20 and 20 - 30 cm. Depending on the depth, the SOC stock is 27.93 ± 1.13 tC/ha at 10 cm depth, 22.37 ± 1.47 tC/ha at 20 cm and 20.79 ± 0.31 tC/ha at 30 cm. According to the age classes of the Arabica coffee systems (ACA), the C/N ratio in our study area averaged 26.94 ± 13.60 for the (5 - 20) year old systems in foumbot and 60.64 ± 48.80 for the (20 - 35) year old systems in Kouoptamo. Depending on the depth, at 10 cm this ratio is higher in Kouoptamo than in foumbot with a maximum value of 57 and 38 respectively for the two subdivisions. In view of the results obtained, it would be important to analyse the types of microorganisms responsible for the decomposition of organic matter which is linked to soil organic carbon.

关键词： Agroforestry Systems Coffee Trees Soil Organic Carbon Noun Division West Cameroon

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Chemical and Bacteriological Analysis of Drinking Water from Alternative Sources in the Dschang Municipality, Cameroon

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Journal of Environmental Protection 2011年第5期2卷 620-628页

作者： temgoua Emile 不详

In the poor zones of sub-Saharan Africa, the conventional drinking water network is very weak. The populations use alternative groundwater sources which are wells and springs. However, because of urbanization, the groundwater sources are degrading gradually making pure, safe, healthy and odourless drinking water a matter of deep concern. There are many pollutants in groundwater due to seepage of organic and inorganic pollutants, heavy metals, etc. Seventeen alternative water points created in 2008, for drinking water in Dschang municipality were examined for their physicochemical and bacteriological characteristics. The results revealed that water from managed points in Dschang is of poor quality. Most of the water samples were below or out of safety limits (standards) provided by WHO. The water is characterized by high turbidity and presence of feacal coliforms. It can be used for drinking and cooking only after prior treatment. This situation shows that water point management was limited only to the drawing up comfort. These water points require installation of suitable surfaces of filtration and the development of a chlorination follow-up plan. Specific concerns of well water were raised and the management options to be taken proposed.

关键词： Sub-Saharan Region Alternative Water Assessing Point Water Quality

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Land Use and Land Cover Change Analysis in Ajei Upland Watershed Community forest, North West Region, Cameroon

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Journal of Geoscience and Environment Protection 2018年第9期6卷 83-99页

作者： Lucie félicité temgoua Gordon Ajonina Hans Berinyuy Woyu Department of forestry Faculty of Agronomy and Agricultural Sciences University of Dschang Dschang Cameroon Cameroon Wildlife Conservation Society Mouanko Cameroon

This study was carried out in Ajei upland watershed community forest in the North West Region of Cameroon with the aim to analyze spatial and temporal dynamics of land cover and land use from 1988 to 2018 and to identify and characterize the agents, drivers and pressures of this change. The databases used were made up of 3 Lands at satellite images (5 TM of 1988, 7ETM+ of 2003 and 8OLI of 2018). field survey, interview and focus group discussion methods were used to identify the activities carried out by the local population and to determine agents, drivers and pressures of land use and land cover change. The Ajei community forest is consisted of four main land cover namely;dense vegetation, sparse or degraded vegetation, savanna and bare soil. Between 1988 and 2018, the proportions of dense vegetation and savanna decreased and that of bare soil and sparse vegetation increased. Analysis showed ongoing deforestation with forest cover loss of about 240 ha in 30 years. for the considered time periods 1988-2003 and 2003-2018, deforestation rates were 1.83% per year and 1.49% per year respectively, signifying on average 8 hectares of forest cover undergoing conversion each year. This lost results from the actions of farmers, cattle grazers and wood extractors who through farming, grazing and lumbering activities pressurize and convert the dense forest cover. Economic motives notably the need to increase household income from a frequent demand for farm and wood products in nearby markets represent the drivers of forest cover change. Controlling grazing activities notably in the dry season to check out the use of fires, community sensitization especially among cattle headmen on the importance of the community forest, reforestation activities through natural regeneration or tree planting are needed in the forest.

关键词： Land Use Land Cover Change Agents Drivers Pressures

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Mechanisms Efflux Pumps of <i>Acinetobacter baumannii</i>(MDR): Increasing Resistance to Antibiotics

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Journal of Biosciences and Medicines 2019年第1期7卷 48-70页

作者： francis T. Dongmo temgoua Liang Wu School of Medicine Jiangsu University Zhenjiang China

Acinetobacter baumannii has greatly increased its degree of resistance to become multidrug resistant (MDR) over the past 30 years and is on the red line of the most widely replicated bacteria according to World Health Organization (WHO). The efflux pumps are the main cause for the increasing antibiotic resistance of A. baumannii originated from nosocomial infection. The progressive resistance of A. baumannii even on the recent drugs (tigecycline and fosfomycin) reduces to very effective antibiotic scale. With attention focused on MDR and pan-drug-resistant (PDR) in A. baumannii multiple works on efflux pumps chemical inhibitor (NMP, PAβN, omeprazole, verapamil, reserpine, CCCP) are still in progress. Certain inhibitors from plants (Biricodar and timcodar, falvone, Mahonia, Dalea versicolor, Lycopus europaeus, and Rosmarinus officinalis) have the capability to have such compounds according to their very significant synergistic effect with antibiotics. In this review we focused on the growth of antibiotic resistance to explain the mechanism of efflux pumps into these different super families and a comprehensive understanding of the extrusion, regulation and physiology role of drug efflux pumps in the essential development of anti-resistivity drugs. We recapitulated the evolution of the work carried out in these fields during the last years and in the course of elaboration, with the aim of increasing the chances of decreasing bacterial resistivity to antibiotics.

关键词： Acinetobacter baumannii RND Efflux Pumps Efflux Transporters Multidrug Resistant (MDR) Efflux Pumps Inhibitors (EPIs)

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The Peripheral Hospital as focal Point for Pacemaker Activity: Review of the Last 300 Implantations Carried out at the Haute Correze Hospital Center

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World Journal of Cardiovascular Diseases 2024年第9期14卷 547-556页

作者： Mazou temgoua Alain Berenfeld Lionel Blasco Benoit Guy-Moyat Cardiology Department Haute Correze Hospital Center Ussel France Cardiac Arrythmia Unit Cardiology Department Dupuytren University Hospital Limoges France

Background: Pacemaker implantation is a very old activity which has revolutionized the cardiology practice throughout the world. This activity is effective at the Haute Correze Hospital Center since more than 20 years. Due to progress in this area, and the increasing request within this center located at the outskirts of town, we set out to evaluate our pacemaker activity in general and more specifically to assess the post-procedural complications in our series patients. Methodology: This was a retrospective longitudinal study. Data were recorded for period of 90 months from 27/05/2016 to 19/11/2023. This data collection was possible via a specific register completed by computerized patient data from the SillageTM software. All files of patients implanted with single or dual chamber pacemakers were included, generator replacements, upgrading procedures and addition of leads were excluded. The sampling was non-probabilistic, consecutive and non-exhaustive. Statistical analysis was carried out using the Excel 2019 spreadsheet and SPSS version 23 software. The quantitative variables were presented as mean ± standard deviation, the qualitative data as proportions. Results: A total of 303 first-time pacemaker’s implantations were carried out during the study period (rate of 40 per year). The average age in the population was 79.7 ± 9.4 years (44 - 99 years) with a male predominance of 63.7% (n = 193). Atrioventricular block (2nd and 3rd degree) was the main indication for pacemaker implantation in 42.9% of cases (n = 130). Patients were most often implanted with a dual-chamber pacemaker (57.7%, n = 175). The approach was most often cephalic in 72.6% of cases (n = 220), followed by the subclavian access in 27.4% of cases (n = 84). The average fluoroscopy time was 7.9 min ± 2.4 (1 - 43). The average irradiation dose in gray/cm2 was 12.4 ± 9.3 (0.22 - 117.5). The average length of hospitalization was 7 ± 4 (2 - 26) days. The overall complication rate at one year was 12.9% (

关键词： Peripheral Hospital Pacemaker Haute Correze Hospital Center

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Physico-Chemical and Bacteriological Quality of the Vegetable Watering Water in the Dschang Town, Cameroon

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Journal of Environmental Protection 2012年第8期3卷 949-955页

作者： Ntangmo Tsafack Honorine temgoua Emile Njine Thomas Laboratory of Applied Biology and Ecology Department of Animal Biology Faculty of Sciences University of Dschang PO Box 67Dschang Cameroon Laboratory of General Biology Department of Animal Biology and Physiology Faculty of Sciences University of Yaoundé I PO Box 812 Yaoundé Cameroon Laboratory of Soil Analysis and Environment Chemistry Department of Soil Sciences Faculty of Agronomy and Agricultural Sciences University of Dschang PO Box 222 Dschang Cameroon

Market gardening, in the swampy lowlands of the Dschangcity, plays an important role in terms of providing employment, and supply the city with fresh products. However, waterborne diseases, which occur in the city, are both attributed to the bad quality of drinking water and sanitation practices. This work aims to characterize watering waters of crop, to assess the health risks associated with the use of these waters. Water from eleven streams and five wells used to irrigate crops were sampled and analyzed once a week for a month. Analyses focused on physico-chemical parameters (temperature, suspended matter, pH, electrical conductivity, COD, BOD5, NO-3 , Al, fe, Cu, Ni), parasitological (helminthes eggs) and bacteriological (total coliforms, fecal coliforms, fecal streptococcus). The results show that, the physico-chemical quality of well waters generally approaches the WHO standards of crop watering water. The physico-chemical of streams waters and bacteriological quality of wells and streams waters are bad, according to WHO guide. These bad quality waters could contaminate crops, some of which are eaten raw, which is surely a cause of the outbreak of waterborne diseases in the city. The waters from streams are more affected. The pretreatment of the water before use for irrigation of vegetables is highly recommended.

关键词： Watering Water Quality Urban Market Gardening Sanitary Risks

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