A paraffin wax and copper foam matrix were used as a thermal energy storage material in the double passes air solar chimney (SC) collector to get ventilation effect through daytime and after sunset. Air SC collector was installed in the south wall of an insulated test room and tested with different working angles (30o, 45o and 60o). Different SC types were used; single pass, double passes flat plate collector and double pass thermal energy storage box collector (TESB). A computational model based on the finite volume method for transient tw dimensional domains was carried out to describe the heat transfer and storage in the thermal energy storage material of collector. Also, equivalent specific heat method was employed to describe the heat storage and release in the mushy zone. Experimental results referred to an increase in thermal conductivity of paraffin wax that supported by copper foam matrix more than ten times. While the ventilation effect was still active for hours after the sun set, depending on the heat storage amount. Maximum ventilation mass flow rate with TESB collector was recorded with value equals to 36.651 kg/hr., when the overall discharge coefficient that was calculated for the system equals to 0.371. Experimental results showed that the best working angle range was 45~60o, and the highest air to the collector approaching temperature appeared to the double passes flat plate collector. Results gave greater heat storage efficiency of (47)% when the maximum solar radiation was 780 W/m2 at 12.00pm, while the energy summation through duration charge time was 18460 kJ. Computational results, depending on the equivalent heat capacity method for heat storage or release from phase change material that supported by copper foam matrix, showed the behavior of paraffin wax melting and solidification situation through periodic for charge and released heat from the solar collector. Also, these results gave agreement approaching the experimental results for the heat storage in the combined heat storage material, with standard error of 16.8%.
هدف البحث التعرف على المعوقات التي تحول دون تطبيق تكنولوجيا المعلومات والاتصالات في كليات جامعة بغداد بأعتبار أن ذلك يمثل مشكلة لابد من الوقوف عندها , ولأهمية مثل هذه المواضيع وضرورة البحث عنها , إذ تحدد مجتمع البحث بالعمداء والمعاونيين في هذه كليات جامعة بغداد للعام الدراسي 2016-2017حيث قام الباحث ببناء اداة خاصة للبحث لغرض الاجابة على هدف البحث الرئيسي ومن خلال أجابات أفراد عينة البحث التي مثلت ما نسبته66% الى ا
... Show Moreتحيا الأمم بتراثها فهو الأساس الذي تنطلق منهُ، وما من أمة إلاّ ولها تراث، وهو سر حياتها وديمومتها ، فالأمة العربية الأسلامية لها تراث تليد التي تشرفت بحمل أقدس رسالة سماوية وأكملها لأمم الأرض، فكانت نبراساً أهتدت به البشرية حتى انتشلتها من واقعها المريض إلى أرغد عيش وأقوم خلق وأنبل نفس .
The study aimed to identify the E-leadership practice at Princess Nora Bint Abdul Rahman University and to explore the obstacles that are facing the leaders in the implementation of E-leadership, in addition to find mechanisms to improve the practice of electronic driving at the university in light of the Corona pandemic. A descriptive analytical approach was used by depending on a questionnaire to collect the needed data. The study sample consisted of (139) heads of departments, attorneys' colleges and support Deanships universities. The study results showed that E-leadership employment recorded a medium to high degree. Especially at university, that publishing decisions electronically and uses technical means in providing its services.
... Show Moreان الحرب الاوكرانية والتصعيد الروسي ضد اوكرانيا يرتبط بصراع جيوسياسي واسع على مناطق القوة والنفوذ والمجالات الحيوية، وتنافس تجاري دولي محتدم على النفط والغاز ومسارات خطوط التجارة الدولية بين اقطاب استراتيجية دولية تتجاوز اوكرانيا، إذ يأتي الصراع ضمن اطار التحولات الدولية الراهنة والصراعات على مناطق القوة والنفوذ الجيوستراتيجي والمكانة الدولية بين القوى الدولية المؤثرة في القضايا والشؤون الدولية، ويبق
... Show MoreThe research aims to achieve a set of objectives, the most important of which is to educate the management of companies operating in the private sector about the advantages and risks of using creative accounting practices, as on the one hand they serve the interests of the company and improve its image, and on the other hand it exposes it to the risks of non-compliance with tax laws and legislation or the risks of default and bankruptcy as a result of exploiting gaps and flexibility in the application Accounting standards, and in line with the objectives and through the research problem that was formulated in the form of a question (Are their creative accounting practices that are reflected in the honesty and fairness of financia
... Show MoreIs to obtain competitive advantage legitimate objective pursued by all organizations to achieve, because they live today in environments of rapid change and dynamic in order to meet the demands of the customer changing as well as intense competition between the organizations, which requires them to get the location of competitive markets in order to do this will remain to do the building and strengthening competitive advantage to be able to achieve, but that this feature is not easy and is not only through the identification and use of a successful strategy for a competitive standard and then manage it successfully. Hence the research problem of determining the sources of differentiation strategy and its impact on the dimensions of compe
... Show Moreتعيش قارة آسيا حالة فريدة تكاد تقترب من حالة أوروبا قبل الحرب العالمية الثانية، فالقارة حاليا تحتوي على العديد من القوى الإقليمية الفاعلة أبرزها الصين وروسيا والهند واليابان، أما القوى الإقليمية الفاعلة في نطاق نظمها الإقليمية الفرعية نجد من أهمها الكوريتين (الشمالية والجنوبية)، وباكستان، وإيران وغيرها، ووجه الاختلاف عن أوروبا هو أن آسيا منطقة شاسعة جغرافياً، وكل نظام إقليمي فرعي فيها هو نظام قاري بحد ذات
... Show MoreThe research aims to present and discuss the accounting bases adopted in accounting for fixed assets in the public sector with an emphasis on its importance in the area of accountability and fixed assets management , based on a realistic problem associated with the use of cash basis accounting in the public sector in Iraq, which are difficult to provide accounting information useful for many users , including the same units and regulatory departments for the purposes of accountability and management of those assets. Search tool has been the organization questionnaire, its results show the importance of financial reporting for provide accounting information about fixed assets relate to the units of the public sector in Iraq fo
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