The avoidance strategy of prey to predation and the predation strategy for predators are important topics in evolutionary biology. Both prey and predators adjust their behaviors in order to obtain the maximal benefits and to raise their biomass for each. Therefore, this paper is aimed at studying the impact of prey’s fear and group defense against predation on the dynamics of the food-web model. Consequently, in this paper, a mathematical model that describes a tritrophic Leslie-Gower food-web system is formulated. Sokol-Howell type of function response is adapted to describe the predation process due to the prey’s group defensive capability. The effects of fear due to the predation process are considered in the first two levels

The present work deals with an experimental investigation of charging and discharging processes in thermal storage system using a phase change material PCM. Paraffin wax was used as the PCM which is formed in spherical capsules and packed in a cylindrical packed column which acted as an energy storage system. Air was used as the heat transfer fluid HTF in thermal storage unit. The effect of flow rate and inlet temperature of HTF on the time of charging and discharging process were studied. The results showed that the faster storage of thermal energy can be made by high flow rate of heat transfer fluid HTF and high inlet temperature of heat transfer fluid. It was found that at 65°C HTF inlet temperature, the melting and solidification pr

In this work we prepared some schiff bases by condensation urea and benzaldehyde or its derevative ( bromo benzaldehyde or hydroxy benzaldehyde ) as ( 1 : 1 ) mole ( urea : benzaldehyde or its substitution ) to prepare compounds ( A1 , B1 , C1 , D1 , E1 , F1 , G1 ) and ( 1 : 2 ) mole ( urea : benzaldehyde or its substitution ) to prepare compounds ( A2 , B2 , C2 , D2 , E1 , F2 , G2 ) . The prepared compounds identified spectroscopic by infrared spectroscopy FT-IR and Thin layer chromotography T.L.C . The force constant calculated from the wave number for the carbonyl stretching from FT-IR chart and by using the following equation K = 4?2C2?'2? The change in double bond order for carbonyl deteremined in according with some past re

يهدف البحث الى التعريف بمشاريع معاملات التأثير العربية، وبيان المجلات العلمية العراقية المشتركة بها ودرجة التأثير لها فضلا عن التعريف بمــــــــوقع المجلات العلمية الأكاديمية العراقية IASJ وعدد المجلات الداخلة فيه. واعتمد البحث على المنهج الوصفي أسلوب المسحي من زيارة المواقع الإلكترونية لمعاملات التأثير، والإطلاع على تقارير معامل التأثير للسنوات 2015-2019 . وخرج البحث بعدة استنتاجات منها ازدياد عدد المجلات ال

     The dialect is part of a broader environment that includes many dialects that have their own characteristics, but they share a set of linguistic phenomena that work on the communication of the members of this environment with each other, and these dialects are old and died, wheras some of them live next to classical, each dialect has a set of common characteristics, The dialectical division is due to the feeling of the place of the one region, that they speak in a way that differs from the image that the inhabitants of the neighboring region walk in, and the dialects of speech in the Arab countries still retain ancient elements that were common in the dialects of Arabs before Islam, as they adhered to many of the

 يتناول البحث تعليم اللغة العربية وما لها من أثر بين التراث والمعاصرة إذ يعُد مقياس رقي أي مجتمع من المجتمعات مقدار عنايته بلغته القومية ، فهي وسيلته واداته للتفاهم في مواجهة المواقف المختلفة التي تتطلب الكلام ، والاستماع ، والقراءة ، والكتابة ، هي  دلالة تحضره وتقدمه في احواله المختلفة ، وهي الشرط الاساس في بقائه ونمائه ، فبدونها يغيب موضوع الحديث عن مفهوم المجتمع القومي لاي شعب من الشعوب ..

In this research is estimated the function of reliability dynamic of multi state systems  and their compounds and for three types of systems (serial, parallel, 2-out-of-3) and about two states (Failure and repair) depending on calculating the structur function allow to describing the behavior of