Regularity of Solutions of Retarded Equations and Application to Sensitivity of Linear Quadratic Controllers to Small Delays

AbstractWe analyze the behaviour of the solution of a linear differential equation of retarded type when the delays vary, for Lp initial conditions, given some p∈[1,∞]. First, we state continuity and differentiability results for the solution viewed as function of the delays. Those regularity results are applied to analyze the small delay sensitivity for quadratic performance index associated to stabilization with a finite dimensional a priori feedback

A Value-At-Risk approach for robust management of electricity power generation

In this paper, we apply Value-at-Risk (VaR) approaches on the problem of yearly electric generation management. In a classical approach, the future is modelled as a markov chain and the goal is to minimize the average generation cost over this uncertain future. However, such a strategy could lead to big financiallosses if worst case scenarios occur. The two VaR approaches we propose, precisely aim at robustifying the model. On a practical point of view, it amounts to introduce a new set of constraints modelling the uncertainties in the original optimization problem or equivalently to change the dual objective function. The new optimization problems are solved as efficiently as the nominal model. Numerical simulations are presented and discussed for this application

Comparative study of the physicochemical quality of water of wells and drilling consumed in the commune of Sinthiou Maléme in the area of Tambacounda (Senegal)

In Senegal, the majority of the regions are not served by the drinking water supply networks. The phenomenon is more pronounced in rural areas, particularly in Sinthiou Maléme commune. For example, communities living in these areas often use well water and borehole. This work has been undertaken to evaluate the physicochemical quality of the water resources consumed by these populations. A total of 24 water samples were taken from the single borehole and 02 publics wells, let be 8 samples per source of water. To assess the quality of these different sources, the physical parameters (electrical conductivity, pH, total dissolved solids and hardness) and chemical parameters (F-, SO42-, PO43-, Fe and NO2-) were analyzed by the photometric method. The results obtained show that, from the physical point of view, drilling water is highly mineralized, slightly hard and has a basic tendency, unlike wells. Chemical analysis shows that well waters are heavily loaded with phosphate ions and nitrites. Based on the parameters analyzed, the quality of the drilling water is chemically acceptable. Studies on the elements of metallic traces will be envisaged to better assess the quality of this drinking water. Au Sénégal, la majeure partie des régions n’est pas desservie par les réseaux d'adduction d’eau potable. Le phénomène est plus accentué en milieu rural notamment dans la commune de Sinthiou Maléme. Ainsi, les communautés qui vivent dans ces zones ont souvent recours à l'eau des puits et des forages. Ce présent travail a été entrepris en vue d’évaluer la qualité physico-chimique des ressources en eaux consommées par ces populations. Au total 24 échantillons d’eaux ont été prélevés de l’unique forage et de 02 puits publics, soit 8 prélèvements par sources d’eaux. Pour apprécier la qualité de ces différentes sources, les paramètres physiques (conductivité électrique, pH, totale des solides dissous et dureté) et chimiques (F-, SO42-, PO43-, Fe and NO2-) ont été analysés par la méthode photométrique. Les résultats obtenus montrent que, du point de vue physique, les eaux de forage sont fortement minéralisées, légèrement dures et présentent une tendance basique contrairement à celles des puits. L’analyse chimique montre que les eaux de puits sont fortement chargées en ions phosphates et nitrites. Sur la base des paramètres analysés, la qualité des eaux de forage est chimiquement acceptable. Des études sur les éléments des traces métalliques seront envisagées pour mieux apprécier la qualité de ces eaux de consommation

Chemical Composition of Distilled Essential Oils and Hydrosols of Four Senegalese Citrus and Enantiomeric Characterization of Chiral Compounds

Peels of four local Citrus species (Citrus sinensis L. Obsbeck, Citrus reticulata Blanco, Citrus maxima Burm. and Citrus aurantifolia christm.) grown in a same locality under the same climatic conditions were subjected to steam distillation. The essential oils and floral waters obtained were analyzed by gas chromatography coupled with a flame ionization detector (CPG-FID) and by gas chromatography coupled to a mass spectrometer (CPG-MS). The essential oils yields were ranged between 0.2 and 0.7 %. The qualitative and quantitative analyses show 74 compounds in all oils samples. The oils were largely dominated by hydrocarbon monoterpenes with limonene as major compound (91.5-94.0 %; 90.4-93.4 %; 77.7-93.7 % and 34.8-51.2 %) in oils from Citrus sinensis, Citrus reticulata, Citrus maxima and Citrus aurantifolia, respectively. In addition to limonene, oils of Citrus aurantifolia contained high amounts of β-pinene (6.8-14.4 %), pcymene (5.8-12.2 %), γ-terpinene (0.3 -7.4 %), neral (1.5-9.4 %), geraniol (1.9-12.7 %). Although presenting the same major compound (limonene), the oils had compositions that were qualitatively and quantitatively different. The enantiomeric analyses showed that the chiral major compounds were (R) - (+) - limonene, (S) - (-) – limonene, (1S) - (-) -β-pinene, (1R)-(+)-β-pinene and (S) - (+) - carvone. The hydrosols analyzed were composed of oxygenated compounds and did not have the same major compound. A qualitative and quantitative difference in chemical composition was noted between the Hydrosols.WBI-Sénégal n ° 2: Production d’huiles essentielles à partir des plantes locales: expérimentation, adaptation et diffusion de technologies »

Contamination Métallique D’une Espèce De Poisson (Brama Brama) De La Côte Dakaroise

Pollution of metal origin constitutes one of the major risks in the world today. The metal elements can be very dangerous to human health when they are present in the environment at high concentrations. Thus, the evaluation of the metal contamination in marine organisms, especially fish, makes it possible to predict a possible contamination of humans. This paper focuses on studying the metal contamination of the beach of Soumbédioune, located at the western frontage of the area of Dakar. This site, where fish products are offloaded, is the home to Canal IV (West Canal), which drains urban wastewater. In this study, we evaluated the concentrations of the metal elements (Fe, Zn 2+ , Cr 6+) in the bodies of Brama brama using a visible spectrophotometry UV. The results obtained show a strong concentration of chromium plates of 24,5 µg/g which is obtained at the level of the liver. Zinc presents a content of 16,7 µg/g at the level of the skin, but it was not detected at the level of the liver and the flesh. The maximum iron content was recorded at the level of the liver with a value of 77,5 µg/g. However, the values obtained were definitely higher than the standards established by FAO and the CEE

Validation of an UV-Visible spectrophotometry assay method for the determination of chlorpheniramine maleate tablets without prior extraction

Methods proposed by pharmacopeias to check the quality of chlorpheniramine maleate tablets are multi steps methods which involve extraction and present issues with repeatability. An alternative method is proposed with a sensitive, reliable, simple and rapid UV-VISIBLE spectrophotometry method developed for the determination without extraction of chlorpheniramine maleate in tablets. The method was validated using the accuracy profile approach with an accuracy ranging from 99.70 to 100.46%. Analysis was done using 0.25 mol/L sulfuric acid, distilled water, and raw material in a room at 23 °C for 25 to 30 minutes. Chlorpheniramine maleate concentration varied from 0.018 to 0.03 mg/mL. The method was found to be specific with the appearance of the corresponding maxima at 265 nm and a correlation coefficient (R2 ) of 0.9993. Limits of detection and quantification were respectively 1.39 × 10-4and 2.26 × 10-3 mg/mL. The tolerance limits for the different concentration levels (75, 100 and 125%) were respectively: 88.37; 92.74 and91.62% for lower limits and 111.03; 108.17 and 108.02% for upper limits. It was observed that the tolerance limits were within the limits of acceptability set at 20%. Consequently, the method was declared valid and reliable for routine analysis of chlorpheniramine maleate in tablets containing chlorphenamine as active principle.Keywords : Chlorpheniramine maleate, tablets, accuracy profile, assay method without extraction, validatio

CHEMICAL COMPOSITION OF ESSENTIAL OILS AND FLORAL WATERS OF EUCALYPTUS CAMALDULENSIS (DEHN) FROM TWO LOCATIONS IN SENEGAL

peer reviewedEucalyptus camaldulensisDehnh leaves from two locations in Senegal (Dakar and Saint Louis) were dried for 14 and 21 days prior to distillation of essential oils by steam distillation and extraction of floral water. Essential oil yields were 0.7 to 2.0%. Oils were analyzed by gaschromatography coupled to a flame ionization detector (GC-FID) and by gas chromatography coupled to a mass spectrometer (GC-MS) equipped with methyl-phenyl–polysiloxane 5% column. Floral waters chemical composition was analyzed by GC-FID and GC-MS equipped with a polar column (VF-Wax ms). Results showed qualitative and quantitative differences in composition between oils from Hann (Dakar) and Bango (Saint Louis). The main constituents of oils were hydrocarbon monoterpenes with 80.9-83.0% for Hann (Dakar) and 51.5-50.6% for Bango (Saint-Louis). Dakar oils contained α-phellandrene as the major compound, with 45.3% and 47.7% after 14 and 21 days of drying, respectively. Other compounds such as p-cymene, α-pinene and 1,8-cineole were identified. The Saint-Louissample showed a very high content of β-phellandrene after 14 and 21 days of drying respectively, and α-pinene and p-cymene was also noted. Furthermore, the floral waters analysis revealed high concentrations of oxygenated compounds whose major part was present in oils. It was also noted qualitative and quantitative differences in floral waters composition. Dakar floral water contained 1,8-cineole (28.2%), terpinen-4-ol (20.3%)α-phellandrene-epoxide (15.9%)and α-terpineol (7%). The Saint-Louis floral water showed a high content of 1,8-cineole (19.2%), α-terpineol (15.4%), terpinen-4-ol (10.8%) and trans-pinocarveol (9.5%

Activités antioxydante et insecticide d’huiles essentielles de Mentha arvensis L. du Sénégal

peer reviewedThis work is part of the global context of valorization of the biodiversity of aromatic plants from Senegal. The aim of the study is to determine the chemical composition of essential oils (EOs) of Mentha arvensis L. and to evaluate their antioxidant and insecticidal activities. For this purpose, leaves of M. arvensis were harvested in Dakar region, Senegal and dried in the shade. EOs were extracted by steam distillation from dried leaves and analyzed by gas chromatography (GC) coupled to a flame ionization detector (FID) and a mass spectrometer (MS). The antioxidant activity of EOs was assessed using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) method while the insecticidal activity was tested by fumigation against Sitophilus zeamais(Motsch.). The results revealed that EOs were dominated by menthol (68.4%), menthyl acetate (16.9%) and menthone (5.0%). The antioxidant activity assay showed that the inhibition increased with the concentration: 38%, 57% and 73% for 10, 25 and 50 mg/ml, respectively; the IC50 was of 19.5 mg/ml. The oils were also effective as insecticide. Mortalities were low after 24 hours and increased strongly after 48 hours with a maximum of 92%. They reached a maximum of 98% for 5 and 25 µl and 100% for 50 and 75 µl after 72 hour