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Eigenvalue criteria for existence of positive solutions to singular third-order BVPs via the index-jump property
No full textMonitoring gear fault by using motor current signature analysis and fast kurtogram method
No full textPhenolic contents and antioxidant activity of orange varieties (Citrus sinensis L. and Citrus aurantium L.) cultivated in Algeria : peels and leaves
No full textDynamic performance of fuel cell power module for mobility applications
Get PDFFuel cell powered vehicles have been developed as another alternative to internal combustion engine powered vehicles
for some applications including passenger cars, buses, trains, motorcycles, forklifts, electric wheelchairs, electric
trolleybuses, medical carts, military engines, personal sports craft, mobility devices and other self propelled equipment.
Up to now, many researches have focused on the development of the power module in the Fuel cell vehicles (FCVs)
and the components of these systems such as membranes, bipolar plates, and electrodes. However, our work in this
study focuses on operating the integrated fuel cell power module system efficiently for various operating conditions
such as pressure, relative humidity and operating modes. In our validation we have utilized PEMFC single cell, with
active area geometry 16 cm2
and of 120 cm2
. Some results obtained in our study shown significant performance indicators
for PEMFC stack (composed of 2 cells and 4 cells in a series) at different humidification level
المخاطر المرتبطة برأس المال البشري وكيفيات إداراتها
No full textص. 9-31يسعى هذا المقال للإجابة على السؤال الرئيسي التالي : كيف يمكن أن يكون رأس المال البشري مصدرا للخطر؟ وكيف يمكن إدارة المخاطر المرتبطة به؟ حيث يعد رأس المال البشري أحد مفاتيح نجاح المؤسسات، فهو يقوم بإدارة كل عوامل الإنتاج الإخرى في المؤسسة لكنه يمكن في كثير من الأحيان مصدرا لمخاطر تكون عائقا أمام تنفيذ خطط المؤسسة وتحقيق أهدافه
Etude du comportement de transformateur de puissance lors de la variation de la charge
No full textL’étude du transformateur en régime de fonctionnement perturbé, l’identific ation de ces perturbations ainsi que leurs origines ont une importance particulière pour le choix et le dimensionnement du transformateur ; et même pour l’optimisation de l’exploitation de l’énergie électrique mise à la disposition du consommateur. Dans le but d’étudier le comportement des transformateurs de puissance suite aux variations brutales de la charge ; nous avons développé le logiciel ERPT (version 1.1 2010) qui permet – entre autres – la simulation des différentes grandeurs électriques l ors de l’augmentation ou de la réduction de la puissance demandée par les récepteurs. Cette étude permet d’identifier et d’analyser les phénomènes accompagnant ce changement d’état de fonctionnement afin de les prendre en considération pour le choix et l a sélection des caractéristiques optimales des transformateurs dans le cas où ces manœuvres de charge seront probable
Effect of the AL2O3 and BaO addition on the thermal and physical properties of ternary glass system (B2O3- BaO-AL2O3)
Get PDFIn borate glasses, the main structural units are the [BO3] triangles and [BO4] tetradral which form different superstructural units like; boroxol rings, metaborate rings and chains, pentaborate, diborate, triborate and pyroborate. In this work, the Barium aluminoborate glasses were prepared. Some of properties were investigated by measure like density and chemical durability and the other by calculs. The dilatometric curves were determined and they revealed that the temperature of transition (Tg) and softening (Ts) and the dilatation coefficient increase by addition of Al2O3 and BaO conten
Ziziphus Lotus and Euphorbia bupleuroides Algerian Honeys
No full textTwo Algerian honey types of semi-arid regions are characterized. Botanical origin is controlled by
qualitative and quantitative melissopalynology. Based on dendrograms test, the 27 studied samples were
classified into three homogeneous groups. The control analyzes showed that they are of good quality in
agreement with the Codex Alimentarius. For discriminating between groups, physico-chemical parameters and
phenolic and sugar composition were measured. But it is only the pH, free acidity, electrical conductivity and
specific rotation that were powerful to differentiate unifloral Ziziphus Lotus group,
Euphorbia
and multiforal
honeys containing
Ziziphus
.
Ziziphus lotus
honey presented specific characteristics, with high pH (4.96 ± 0.91),
dextrogyrous specific rotation (-1.41 ± 7.55°) and high diastase activity (36.06 ± 10.06). While,
Euphorbia
honeys were within honey standards, with poor proline content (114.3 ± 30.3ppm) and low Diastase activity
(14.6 ± 4.1Ush).The mineral fraction of ziziphus honey reveals the predominance of potassium, calcium and
sodium with a constant presence of iron and magnesium. Finally, correlations analysis suggests the existence
of a strong relationship between color and flavonoïd fraction, which is present in significant amounts
(15-30 mg EQ/100g) compared to rates usually found in European monofloral honeys (1-6 mg EQ/100g), which
is remarquabl
Modelling of interference fits with taking into account surfaces roughness with homogenization technique
No full textدور وكالات التصنيف الإنتمائي في تقييم القيم المالية وأثرها على سير الأسواق المالية الدولية
No full textص. 33-66تتولى وكالات التصنيف الإنتمائي( وكالات التنقيط الدولية) تقييم ملاءة المؤسسات والدول المصدرة للسندات، مساهمة بذلك في توجيه قرارات المستثمرين لإقتناء تلك السندا