حياة عواشرية , فريدة فرحات

كلية العلوم الإنسانية والاجتماعية-جامعة 8 ماي 1945 قالمة · الجزائر

استقطب الإنسان اهتمام الفلاسفة، منذ عابر العصور، حيث كان مدار أمهات المشكلات الفلسفية، التي سايرها هؤلاء في أطاريحهم، من الإغريق في فلسفة السقراطية، فأخذه سقراط محورا للحوار، وموضوعا مارس عليه منهج التجاه لا لسقراطي، منهج التهكم والتوليد، ثم تناوله أفلاطون في فلسفة المثالية فارضا قد استه في عالم المعقولات، الذي أسسه بالجوهر الما هوي، القائم في فاعلية الذات، وفي الفلسفة الأرسطية كان موضوعا محوريا في المنطق والسياسة والأخلاق، وتم الاهتمام بهذا الكائن في الفلسفات الحديثة، فتناوله ك انط كعقل يحض بالقداسة، والمطلقية التيتجعله في ملئ من الوقوع في الخطأ، ليكون بعد ذلك موضوع الكوجيتو الديكارتي، الذي صاغه ديكارت وفق مقولته الشهيرة " أنا أفكر أنا موجود "، مبررا بذلك الوجود بالماهية التي تسبقه وتؤسس مشروعيته، أما في الفلسفات المعاصرة قد تناول إدموندهوسرل معدلا الكوجيتو الديكارتي في إضفاء موضوع التفكير

حسام الدين السيد, سالم بن عبدالله بن سالم الحارثي

كلية العلوم والاداب-جامعة نزوى · عمان

شيونغ يوان, وليام روبرتس

جامعة الملك عبدالله للعلوم والتقنية · السعودية

Electric field can be a viable method in controlling various combustion properties. Comparing to traditional actuators, an application of electric field requires very small power consumption. Especially, alternating current (AC) has received attention recently, since it could modulate flames appreciably even for the cases when direct current (DC) has minimal effects. In this study, the effect of AC electric fields on small coflow diffusion flames is focused with applications of various laser diagnostic techniques.Flow characteristics of baseline diffusion flames, which corresponds to stationary small coflow diffusion flames when electric field is not applied, were firstly investigated with a particular focus on the flow field in near-nozzle region with the buoyancy force exerted on fuels due to density differences among fuel, ambient air, and burnt gas. The result showed that the buoyancy force exerted on the fuel as well as on burnt gas significantly distorted the near-nozzle flow-fields. In the fuels with densities heavier than air, recirculation zones were formed very close to the nozzle exit. Nozzle heating effect influenced this near-nozzle flow-field particularly among lighter fuels. Numerical simulations were also conducted and the results showed that a fuel inlet boundary condition with a fully developed velocity profile for cases with long fuel tubes should be specified inside the fuel tube to obtain satisfactory agreement in both the flow andtemperature fields with those from experiment.With sub-critical AC applied to the baseline flames, particle image velocimetry(PIV), light scattering, laser-induced incandescence (LII), and laser-induced fluores- cence (LIF) techniques were adopted to identify the flow field and the structures of OH, polycyclic aromatic hydrocarbons (PAHs), soot zone. Under certain AC condi- tions of applied voltage and frequency, the distribution of PAHs and the flow field near the nozzle exit were drastically altered from the baseline case, leading to the formation of toroidal vortices. Increased residence time and heat recirculation inside the vortex resulted in appreciable formation of PAHs and soot near the nozzle exit. Decreased residence time along the jet axis through flow acceleration by the vortex led to a reduction in the soot volume fraction in the downstream sooting zone. Electromagnetic force generated by AC was proposed as a viable mechanism for the formation of the toroidal vortex.By varying applied AC in a wide range of frequency and voltage, several insta- bility modes were observed, including flicking flames, partial pinch-off of flames, and spinning flames. High speed imaging together with Mie scattering techniques were combined to reveal the flame dynamics as well as the flow structure inside the flames. Original steady toroidal vortices triggered by AC were noted to exhibit axisymmetric axial instability in the flicking and partial pinch-off modes and non-axisymmetric azimuthal instability in the spinning mode. Electrical measurements were also conducted simultaneously to identify the voltage, current, and electrical power responses. Integrated power was noted to be sensitive to indicate subtle variation of flames properties and to the occurrence of axial instability.Under low frequency AC forcing with electrical conditions not generating toroidal vortices, responses of flames were further investigated. Several nonlinear flame responses, including frequency doubling and tripling phenomena, were identified. Spectral analysis revealed that such nonlinear responses were attributed to the combinedeffects of triggering buoyancy-induced oscillation of the flame as well as the Lorenz force generated by applying AC. Phase delay behaviors between the applied voltage and the heat release rate (or flame size) were also studied to explore the potential of applying AC in controlling flame instability. It was found that the phase delay had large variations for AC frequency smaller than 80 Hz and became saturated at over 80 Hz, which has been explained based on the interaction between the buoyancy and ionic wind. Electrical measurement showed the power consumed by the AC was smaller than 0.01% of the heat release rate from the flame.To improve the understanding on the electric current resulting from applying electric field on flames, a simplified one-dimensional model was developed in that the reaction zone was modeled as a thin ionized layer. Model governing equations were derived from species equations by implementing mobility differences depending on the type of charged particles, especially between ions and electrons. The result showed that the sub-saturated current along with field intensity was significantly influenced by the polarity of DC due to the combined effect of non-equal mobility of charged particles as well as the position of the ionized layer in a gap relative to two electrodes. Experiments with quasi-one-dimensional flames under DC were conducted to substantiate the model and measured currents agreed qualitatively well with the model predictions.

Lynda Messaoudi, Sylia Menchi, Zahoua Mehenni

كلية العلوم الإنسانية والاجتماعية-جامعة عبد الرحمان ميرة - بجاية · الجزائر

Cette étude abordée l'interrogation sur" l'épuisement professionnel chez les gynécologues de l'EHS Sbihi Tassadit de Tizi ouzou. L' objectifs de cette recherche est de mesuré le degré de l'épuisement professionnel et les facteurs qui provoque ce dernier. Pour vérifier les hypothèses, on a référée à deux outils d'investigations : - Une échelle de MBI (Maslach burn out Inventory) - L'entretien clinique Les résultats mettent en évidence la confirmation de la première hypothèse qui suppose le degré de l'épuisement est défirent. La confirmation de la deuxième et les deux dernières hypothèses qui supposent le milieu est la surcharge de travail. Donc on constate que le burn out est un ensemble de symptôme résultat de la dégradation du rapport subjectif au travail, cela se traduit par un épuisement émotionnel, physique et psychique. La personne a la sensation d'être vidée de ses ressources

Sarah Mezine , Ghania Meftah , Mounir Ahmed Tayeb

كلية الاداب واللغات-جامعة مولود معمري - تيزي وزو · الجزائر

بوجبيرة عبدالرحمن, مكي عبدالمنعم

كلية التكنولوجيا-جامعة محمد بوضياف - المسيلة · الجزائر

Les drones (engins volants sans pilote) sont de plus utilisés dans diverses applications civiles et militaires et parmi les caractéristiques majeures de ces systèmes sont instables en boucle ouverte, dans ce travail on s’intéresse à la description et la modélisation dynamique du quadrotor (hélicoptère a quatre rotors) tenant en compte les divers phénomènes physiques, qui peuvent influencer sur la dynamique d’une structure volante. Dans ce travail on a fait une étude théorique sur les systèmes aéronautique te on a spécifie le quadrotor, puis on a appliqué une commande non linéaire basée sur les régulateurs PID à gains adaptatifs. Les gains sont ajustés par deux méthodes (la logique floue et la théorie de Lyapunov).

ليدريسي لخضر , مغنية قوعيش

كلية العلوم الاجتماعية-جامعة عبد الحميد بن باديس مستغانم · الجزائر

Karima Merrir, Merri

كلية العلوم الإنسانية والاجتماعية-جامعة عبد الرحمان ميرة - بجاية · الجزائر

A travers cette recherche, nous nous découvrirons les techniques de motivation adoptées par l'entreprise IFRI et voir leurs impact sur la performance du personnel au travail

محسن عدس, هيام جميل محمد زايد الرجبي

كلية العلوم التربوية-جامعة القدس · فلسطين

Fateh Haddadou, Lynda Cherief, Rachid Mehaddene

كلية هندسة معمارية-جامعة مولود معمري - تيزي وزو · الجزائر

En général il n’existe pas de méthode de composition du béton qui soit universellementreconnue comme étant la meilleure. La composition du béton est toujours le résultat d’uncompromis entre une série d’exigences généralement contradictoires. De nombreusesméthodes de composition du béton plus ou moins compliquées et ingénieuses ont étéélaborées. On notera qu’une étude de composition de béton doit toujours être contrôléeexpérimentalement et qu’une étude effectuée en laboratoire doit généralement être adaptéeultérieurement aux conditions réelles du chantier.Notre travaille consiste à comparer les résistances données par la composition 1/3 de sableet 2/3 de gravier et celle obtenus par la composition 1/3 de sable et 2/3 de gravier déterminéepar deux essai différents, essai non destructif on utilisant l’ultrason et essai destructif enutilisant l’écrasement des éprouvettes. Pour cela en a procédé de la manière suivante :Confectionné des éprouvettes cylindrique de dimension 16*32 cm puis en les à conservéesdans deux états différentes (à l’aire et à l’eau).Les résistances donnée par la composition 1/3sont meilleure que celle de la composition 1/2, ce gain de résistance est plus important à l’eauque à l’aire, et la caractérisation par l’écrasement est plus fiable que l’ultrason.