The Impact of Climate Variabilities on the Water Resources of Nyong River (Cameroon) during Few Anterior Decades

The Nyong River is situated in south Cameroon. The study of the impact of climate change on the water resource of the River shows that its precipitations and flow rate are decreasing. This negative effect is reinforcing by the fact that the water of the River is collected to feed the population of Yaoundé, the political capital of Cameroon and its environs. Given that no action can stop the variability of climate factors, it is necessary to ameliorate the management of water resource of Nyong River.

Comparative Study on Telecommunications Base Stations＇ Power Supply Systems on Remote Sites in the Northern Part of Cameroon

The TBS （telecommunications base stations） on remote sites in the northern part of Cameroon are mainly supplied by a system of two generating units. Only a few TBS located in the Waza and Benue National Parks are powered by a PV （photovoltaic） solar system to avoid any disturbance to wildlife. It is against this background that we decided to do a comparative study on these two systems. This study focuses on the reliability of electrical quantities, the environmental impact and the installation and operating costs of these two major systems namely the GU （generating unit） system comprising two generating units and the PV system. In conducting this study, we took a sample of TBS including those located in the Badjouma and Waza localities. After collecting data from mobile telephony operators, measurements of electrical quantities on the sites for twelve consecutive months and updating costs, their operation reveal indicators that are surprising, to say the least. Concerning the reliability index, the PV system is estimated at 99.9% as against 97.8% for the GU system. As for environmental impact, the mass of CO2 released by the GU system reached 1,707.5 tons in 25 years for a single TBS while the PV system produced no emissions. In addition to its contribution to climate change, the GU system pollutes its immediate environment through the spillage of waste and production of deafening noise. On the other hand, economic analysis shows mixed results. The GU system has a lower installation cost of $6,640 as against $174,550 for the PV system, whose investment cost is its main handicap. Regarding operating costs, the GU system peaks at $923,940 in 25 years while the PV system requires only $487,550 for the same duration.

Dynamics of the Vegetation Landscapes of the Mbere Valley’s National Park and Its Southern Periphery

The present study is about the dynamics of the vegetation landscapes of the Mbere Valley’s National Park and its southern periphery (MVNP). The physical and human characteristics of this area, translated by an inter-twining of natural, anthropic and institutional factors, predispose its vegetation cover to a dynamic which can be progressive or regressive according to the dominant factor. The present study aims at reconstituting the various space-time variations of the MVNP vegetation cover and its periphery between 1987 and 2014, and at determining the processes and the factors having supported these space-time variations of vegetation cover. The methodological step consists of an association of fieldwork and remote sensing in order to characterize the vegetation cover, to reconstitute the evolution of the vegetation cover and to determine the main factors of the processes of this evolution or dynamic. The diachronic analysis shows that the dynamics of the vegetation cover was marked by a progressive evolution between 1987 and 1999, and a regressive evolution between 1999 and 2014. On the base of fieldwork observations and the socio-economic surveys, it arises that the dynamics of the vegetation cover of the valley of Mbere and its periphery is subjected to the combined influence of the natural conditions, from the recurring anthropic disturbances as well as the weight of regulatory measures.

Assessment of Wind Energy Potential in the Sudanese Zone in Chad

In this study, wind characteristics and wind power potential are analyzed for three meteorological stations in the Sudanese zone of Chad for the period of 35 years (from 1975 to 2010). Assessment of the wind power potential was carried out using the two parameters of Weibull distribution. Results of the study shows that the average annual wind speeds at 10 m above ground for Moundou, Pala and Sarh are 2.69, 2.33 and 1.91 m/s, respectively. The mean annual value of the Weibull shape parameter k and scale parameter c range from 2.376 to 3.255 and 2.099 to 3.007, respectively. The maximum annual power density of 204.85 W/m2 was obtained at Moundou. Results of this study further shows that the selected locations are not suitable for large-scale wind energy production at 10 m altitude. However, by extrapolation, assessment of wind speed at 67 m altitude combines with wind turbine Vestas 2 MW/80 that adapts to the Sudanese local conditions, and the wind power potential can be exploited for water pumping, heating and production of electricity.

More Value of Maroua Clay in the Formulation of Ceramic Products (Terracotta, Earthenware, Stoneware, Porcelain)

As a part of the framework of the development of ceramic products, scientific research continues this idea that clays are essential vehicles for local development in Africa;and therefore they deserve to be made profitable. This scientific work has the advantage of providing a solution to the housing of the Sahel area. On the other hand, this study can effectively serve as the basis of data in the formulation of ceramics from clay Maroua, in the region of the Far North Cameroon, for a large-scale industrial operation. Thus, two samples of materials respectively KO1 and IP2 have been the subject of a preliminary chemical and mineralogical size rheological study. Once formed, the tubes containing the KO1 and PI2 materials have undergone heat treatment at successive temperatures of 900°C, 1000°C and 1100°C. The baked products obtained have also been the subject of a study of resonance, coloring density, loss on ignition, water absorption, linear shrinkage, porosity and mechanical compression.

Physico-Chemical and Petrographic Characterization of Carbonated Rocks of Mintom (South-Cameroon) and Their Potential Uses

The characterization of carbonated rocks of Mintom allowed identifying three features (massive limestone, banded limestone and dolomite). Samples taken in these features were subjected to the physico-chemical analyses and to the mechanical tests. The results obtained show a convergence in the mineralogical composition in particular in the calcareous features (smectite, micas and calcite);the dolomite feature being mainly constituted by dolomite associated with the smectite. The chemical composition allows finding contents raised in CaO, in all the samples. However, in the dolomite and the banded limestone, the concentrations in MgO and in SiO2 are also important. The mechanical properties showed a good compression resistance for the massive limestone and the dolomite, the mechanical behavior of the banded limestone being low. The exploitation of these results allows recommending carbonated rocks of Mintom in the production of the clinker, agricultural amendments and in the constructions of the civil engineering.

Estimation of Hydraulic Conductivity of Soils at a Watershed-Scale Using Porchet’s Method: Application in the Olezoa Waterhed, Yaounde, Cameroon

Contamination analysis of the unsaturated zone requires information on the spatial variability of hydraulic conductivity. Two types of hydraulic tests (variable and constant charge) were identified to estimate the spatial variability of the hydraulic conductivity of the surface portion of the unsaturated zone in the Olezoa watershed. These tests were performed on 100 holes at depths ranging between 50 and 90 cm, spread throughout the watershed. The hydraulic conductivity values obtained at 50 and 90 cm are close to the absolute value for each method. However, they show a difference of 10-1 m/s between the two types of test regardless of the depth of investigation. The representation of data in the graph indicates a staircase quartile distribution for the variable charge test. The test at constant charge, rather presents a log normal distribution which is also supported by the Kolmogorov-Smirnov test. Hydraulic conductivities have a random component and a spatial organization which results from soil and/or morphological factors. This organization thus permits the distinction of zones which could show high pollution risk.

Compressed Bricks Made of Makabaye and PitoaréClay: Implementation and Production

In a strong commitment to economic valorisation that began a decade and relevant contribution to the problems of housing and creation of small jobs response, the Cameroonian government has invested heavily in promoting use of local materials through the creation of MIPROMALO (Mission for Promotion of local Materials) in 1991 (economic crisis), and through the signing of government circular from the Prime Minister, thus placing its development policies in prior to any development strategy more distant prospect. It was then that housing through development of local building materials becomes one of major policy priorities of Cameroonian’s government. However, there is a low valuation thereof despite availability of local materials and political will expressed in Circular No. 002/CAB/PM of 12 March 2007 on the use of local materials in construction of public buildings. In this study, we analyse the contribution that can play promotion of local materials in construction in the Sahel zone which for a harmonious sustainable development. Specifically, it’s to highlight the added value of using local materials, propose strategies for implementation and production of compressed bricks. This scientific work has therefore a double interest, scientific and technological industrial view and contributes to the development, promotion of local materials and the development of soil and/or basement areas. We arrived after analysis of our data to the conclusion that valuation of clay materials from Maroua’s town was a factor for economic growth and sustainable development. This inventory allows us to implement and produce prototypes suitable compressed bricks, shapes of housing in Sahel zone. However, physical and geotechnical tests on materials clay (raw materials for production of bricks), allow us to better assess characteristics of clay before production of bricks. Well after we submit our bricks to various mechanical and technological tests to assess their ability to withstand loads in extreme temperature conditions of Sahel zone.

Optimisation of Decolourisation Conditions of Crude Shea (<i>Vitellaria paradoxa</i>Gaertner F) Butter: Black Type

In the present study, response surface methodology applying Doehlert experimental design was used to investigate decolourisation parameters of crude black shea butter. The decolourisation process was significantly influenced by three independent parameters: contact time, decolourisation temperature and adsorbent dose. The responses of the process were oil loss, acid value, peroxide value and colour index. Contour plots of the decolourisation responses were superimposed and well defined the optimum zone. The optimum decolourisation conditions were found to be: contact time (30 min), temperature (72℃ - 95℃) and adsorbent dosage (1.5 - 2.5 mass %).

Optimisation of Decolourisation Conditions of Crude Shea (<i>Vitellaria paradoxa</i>Gaertner F) Butter: Yellow Type

In this study, response surface methodology applying Doehlert experimental design was used to optimise decolourisation parameters of crude yellow shea butter. The decolourisation process was significantly influenced by three independent parameters: contact time, decolourisation temperature and adsorbent dose. The responses of the process were oil loss, acid value, peroxide value and colour index. Contour plots of the decolourisation responses were superimposed and well defined the optimum zone. The optimum decolourisation conditions were found to be: contact time (30 min), decolourisation temperature (80℃ - 95℃) and adsorbent dosage (1 - 2 mass%). These conditions gave decolourised shea butter with the following responses;oil loss (6.2% ± 0.2%), peroxide value (1.7 ± 0.1 meq O2/kg), colour (0.21 ± 0.05 Lovibond yellow) and acid value (25.6 ± 0.7 mg KOH/g).

Quasi-Horizontal Arrangement of Solar Panels in Equatorial Zones： Problems and Proposed Solutions

Solar panels are oriented to the North （South） when the site is in the South （North） with a tilt angle close to the latitude. In the equatorial zone, the panels are quasi-horizontally arranged. This situation caused some problems： the panel is more rapidly covered with dust or salty mud that decreases its performance and degrades the protective glass. To overcome these difficulties, we evaluated theoretically and practically the energy lost by an incorrect tilt. The results are rather encouraging. Just 1.5% of total energy is lost when we tilted the panel at 10.0°. In practice, we realized that the loss of energy is fewer than we calculated it because of the reflected solar rays.

Selection Strategy for Chestnut (<i>Castanea sativa</i>Mill.) Families Originating from Contrasting European Populations

Genetic material originating from contrasting European chestnut (Castanea sativa) populations of Greece, Italy and Spain was evaluated in a common garden test situated in Greece. The aim of the study is to device an appropriate selection strategy by identifying and conserving superior genotypes for current and future use in breeding programs. Breeding material consisted of 143 open-pollinated families growing in a common garden provenance-progeny experimental trial. Growth trait genetic parameters were estimated and response to selection was evaluated using family, within family and combined selection methods. Two models were employed for the estimation of family variance and genetic parameters. The CVA varied between 12.1% and 67% among traits and models, showing an increasing trend with age. Heritability estimates were high;however their variation with age was irregular. Selection of superior families regarding three years of measurement for height, diameter, volume index and number of leaves showed a potential gain of 12% - 25%, 12% - 28%, 33% - 73% and 21% - 49% over the mean of all plants. Genetic gain for volume index was the highest among the traits studied and the joint model used presented a more effective selection strategy. Results indicate that the experimental trial studied presented substantial genetic variation and sufficient genetic gain opportunities for quantitative traits of economic importance. These findings suggest that inferior trees can be rogued from the experimental trial and a seedling seed orchard of Castanea sativa in Greece can be established.

Simultaneous Voltammetric Determination of Cd^(2+), Pb^(2+), and Hg^(2+) Ions Using Aminosepiolite-Coated Glassy Carbon Electrode: Optimization of Detection Parameters via Response Surface Methodology

Adsorptive stripping voltammetry using a glassy carbon electrode modified by a film of aminosepiolite was utilized for simultaneous pre-concentration and trace detection of cadmium,lead,and mercury ions in aqueous solution.The modified sepiolite exploited as electrode material was obtained by grafting on its surface of[(3-(2-aminoethylamino)propyl)]trimethoxysilane(AEPTMS).The results demonstrated that the amine groups on sepiolite efficiently affected the voltammetric detection of heavy metals.The full factorial design matrix and response surface methodology were applied in designing experiments,to determine the optimal conditions and to evaluate their mutual interactions.The high values of adjusted R2 obtained of the fitted model show that the experiments data were well explained by the model,which then allowed to acquire optimum parameters for the electroanalysis and detection of the analytes by differential pulse voltammetry.At pH 6.5 of accumulating medium,with an electrolysis potential of-0.9 V and in the concentration range of 10^(−8) M to 10^(−9) M,calibration plots were obtained.The limits of detection(3Sd/m)were 8.689×10^(−10) M,8.197×10^(−10) M,and 8.099×10^(−10) M,respectively,for Cd^(2+),Pb^(2+),and Hg^(2+)ions.The interference effect of several cations and anions on the response of the analytes was also evaluated,and finally,the sensor was applied to the simultaneous detection of metal ions in tap water with satisfactory recovery rates.