Illumination Level Effects on Macroscopic Parameters of a Bifacial Solar Cell

This study presents a method based on the experimental measurement of the short-circuit current (Icc) and the open circuit voltage (Vco) of the solar cell. It permits the determination of recombination parameters such as: diffusion length (L), back surface recombination velocity (Sb), intrinsic junction recombination velocity (Sjo), and macroscopic parameters in particular, the shunt and series resistances of a bifacial solar cell for various illumination levels (n). Illumination level effects on macroscopic parameters are highlighted.

Effect of Incorporation of Chips and Wood Dust Mahogany on Mechanical and Acoustic Behavior of Brick Clay

An experimental study was carried out on bricks using local materials in order to take into account the waste wood management to protect the environment and to reduce the cost of the habitat. Chips and sawdust were built-in clay bricks in order to study their influence on the compressive strength, Young’s modulus and the speed for soundproofing. Testings in compressive strength were made on the parallelepiped clay bricks, stabilized with different percentages of cement, with incorporation to various percentages of sawdust or wood chips (Mahogany), using a universal press. Young’s modulus was measured from the speed of sound by the ultrasonic method. The results obtained show that the incorporation of mahogany tree chips in the stabilized brick at 8% of cement, does not have much effect on the compressive strength. It was found that the incorporation of chips or sawdust on the clay brick, does not improve the compressive strength. The Young’s modulus decreases with increasing content of sawdust and practically remains constant regardless of the content of chips at 4% and 6% of cement. The clay brick mixed with 8% of mahogany sawdust can be an acoustic barrier.

Evaluation of Potential Extracts Antioxydant (Aqueous, Hydro-Ethanolic and Ethanolic) of an Aquatic Plant from the River Djoue (<i>Ledermanniella schlechteri</i>)

The aim for this present study was to evaluate the antioxidant potential of aqueous extracts (AE), hydro-ethanolic extracts (HE) and ethanolic extracts (EE) obtained from an aquatic plant (L. schlechteri) using a simple and fast method that is the CCM. This method revealed the presence of phenolics and flavonoids at different levels but with higher antioxidant activity in EE compared to AE. Among the two families of antioxidants evaluated, the phenolic compounds were found to be higher on the EE (5.85 mgEAG/MS) followed by the HE (5.06 mgEAG/MS) and less and less important on the AE (3.661 mgEAG/MS). While the less significantly elevated flavonoids showed values of 1.146 mgECa/MS for EE, 0.406 mgECa/MS for HE et 0.181 mgECa/MS for AE. However, the anti-free radical activity was also evaluated. Unlike the antioxidant activity, the ant-free radical activity with a greater IC50 was observed on AE with a rate of 66.66 mg/mL, then less on the hydro-ethanolic and ethanolic extracts, respectively at levels of 26.15 mg/mL et 19.18 mg/mL.

Development of a Process for Formulating Infant Flours from the Almonds of <i>Treculia obovoidea, Terminalia catappa</i>Linne as well as <i>Ipomoea batatas</i>Lam Leaves

In response to the malnutrition problem affecting children in Congo Brazzaville, we made three cooking-type infant flours from Treculia obovoidea, Terminalia catappa L. almonds and Ipomoea batatas L. leaves. The nutritional quality of the three infant flours we developed indicates 11.07% - 12.47% protein content, 9.92% - 14.87% fat content, 58.85% - 68.06% carbohydrate content, 1.50% - 2.18% ash and an energy intake varying between 399.84 and 439.37 Kcal. Functionally, our prepared flours have a water absorption capacity between 219.05 and 317.86 mL/g, an oil absorption capacity of 0.19 mL/g, a water solubility index varying from 29.66 - 41.03 and a swelling capacity of 250% - 320%.

Modeling of the Drying Kinetics of Two Extreme Parts of the Pulp of Gamboma Yam (<i>Dioscorea cayenensis</i>): Yellow Part (Head) and White Part (Tail)

The study on the modelling of the drying kinetics of two extreme parts of the Gamboma yam pulp, the yellow part (head) and the white part (tail), was carried out to evaluate the behaviour of these two parts during drying. This evaluation was carried out in the oven at 70?C and in the microwave at 280 W. The main aim of this work was to study experimentally while modelling the drying kinetics of the food and at the same time to evaluate the influence of temperature on two parts (head and tail) of the Gamboma yam. The effect of temperature on the food revealed the following results: a progressive decrease of the water content during the drying process in both the oven and the microwave. This experiment showed that during the drying of the two parts in the oven and in the microwave, the loss in mass evolves from the tail (white part) to the head (yellow part), because the white part is the youngest in terms of formation and the head, the oldest part in terms of formation. In the microwave and at 280 W, the drying of the yam is faster than in the oven at 70?C. During the modelling, four different mathematical drying models were used, namely Newton’s, Page’s, Henderson and Pabis’ and finally Midili’s, to assess the goodness of fit on the drying of the product while comparing their respective parameters R2, χ2 and RMSE. The comparison of the statistical parameters led to the selection of the Midili model as the one with better goodness of fit and better drying characteristics so as to obtain more expressive drying curves in contrast to other models.

Loaded Rubber-Like Materials Subjected to Small-Amplitude Vibrations

This paper proposes a constitutive law and a method for characterizing highly preloaded viscoelastic materials subjected to linear （small-amplitude） vibrations. A multiplicative non-separable variables law has been suggested to model the behavior that depends on both stretch and time/frequency. This approach allows splitting the intricate combined test performed simultaneously on both stretch and frequency, generally in a limited experimental domain up to 100 Hz, into two independent tests. Thus, on one hand, the dynamic complex modulus dependent on frequency alone is evaluated on the basis of vibration tests in a large experimental domain up to 100 kHz. On the other hand, energetic parameters are determined from a quasi-static hyperelastic tensile test. The complex modulus, dependent on both stretch and frequency, is then deduced from the results acquired from uncoupled investigations. This work shows that, in extension, the elastic modulus increases with increasing stretch, and the loss factor decreases with increasing stretch; while, in compression, around the material undeformed state, the modulus increases as the stretch increases till a certain value of compression stretch （upturn point depending on material characteristics）, and then the modulus decreases as the stretch increases. Globally, preload rigidifies materials but reduces their damping property. These results closely match a well-known observation in solid mechanics.