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%.
Malaysia is linked to the countries of the Middle East by a historical relationship identified by a number of factors and determinants that affected the developments of that relationship, especially its relentless endeavor to preserve its Islamic identity with the leadership of the rest of the other ethnicities, in addition to those factors and international determinants that directly affected the typicality of this relationship and perhaps the United States stands At the forefront of who represents this international variable, as it is considered the Middle East region as a core region and within its vital field, and therefore any analog relationship in the field of international relations and one of its parties is the countries of the
... Show Moreمجتمع مدني ام مجتمع اهلي ؟ دراسة لواقع المجتمع المدني في البلدان العربية
Barium–doped TiO2 / n-Si photodetector was fabricated by spray pyrolysis exhibited visible enhancement responsivity profile with peak response at 600 nm flat response between 650 and 900 nm. The quantum efficiency was 30% and specific detectivity was 5x1012 W-1Hz1/2cm at peak response. The GaAlAs laser diode was used to estimate the rise time of the detector.
تزايد اهتمام الحكومات باختلاف أنظمة الحكم فيها والأفكار السياسية التي تؤمن بها، بالضرائب كأحد أدوات السياسة المالية، تسعى إلى أن تحقق من خلالها أهداف اقتصادية واجتماعية وسياسية فضلا" عن الأهداف المالية، إذ إن السياسة الضريبية تصاغ أهدافها باتساق وانسجام مع أهداف السياسة الاقتصادية بشكل عام، و إنما كانت الضريبة عام، ولما كانت الضريبة على هذا القدر من الأهمية فانه لم يكن مستبعدا" أن تحظى بعناية مشرعي ا
... Show MoreThe present study is considered the first on this sector of the Tigris River after 2003. It is designed for two aims, the first is to demonstrate the seasonal variations in physicochemical parameters of Tharthar-Tigris Canal and Tigris River; the second is to explain the possible effects of canal on some environmental properties in the Tigris River. Water samples were being collected monthly. Six sampling sites were selected, two on Tharthar Canal and four along the Tigris River, one before the confluence as a control site and the others downstream the confluence with the canal. For a period from January to December 2020, nineteen physicochemical parameters were investigated including air and water temperature, turbidity, electrical cond
... Show MoreThe reasons for the totality are varied and multiple, some of which are attributed to the methods of the Arabic language as the participant
Verbal and omnipotent differences in the oud of conscience, which are comprehensive reasons for language in all
And some of these reasons are due to the sciences of the Qur'an, such as cessation and initiation
The explanation of the explanation for the multiplicity of words and differences in them, which necessarily led to a dispute jurisprudence
Linked to the origin of disagreement in the interpretation of the totality and its orientation and understanding and to summarize this subject and diverge
Parts and vocabulary did not receive the necessary care and did not absorb the lesson an
Seasonal variations of the species composition and abundance of Cladocera were studied in two stations at the end of the Tigris River and one station at the confluence of the Tigris with Euphrates area, at the beginning of the Shatt Al-Arab River in Al-Qurnah North of Basrah Province, from October 2015 to August 2016. Samples of zooplankton were collected by plankton net 100-µm. mesh size. The population density of Cladocera ranged between 1 Ind /m³ during summer and 211 Ind./m³ during winter at station 1 (Al-Jewaber Bridge). A total of 16 species of Cladocera belonging to 12 genera were recorded in the study. The average density of Cladocera ranged from 23.2 ind./m3 at Station 2 (Hamayon Bridge) to 53.7 Ind./m3
... Show Moreاستهدف البحث الكشف عن المكانة الاجتماعية لطفل الروضة بين أقرانه ، ودلالة الفروق في المكانة الاجتماعية لاطفال عينة البحث التي تعزي الى بعض المتغيرات من خلال الاجابة عن الاسئلة الاتية :
اولاً : ما المكانة الاجتماعية لدى اطفال الروضة بين اقرانهم ؟
ثانياً : ما علاقة المكانة الاجتماعية لدى اطفال الروضة ببعض المتغيرات و ذلك من خلال اختبار الفرضيات الصفرية الآتية :