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%.
The present study aimed at examining the factors that affect the choice of A major among a sample of BA fe(male) students at the levels 3-8 in King Abdulaziz University (KAU), in Jeddah, Saudi Arabia. To meet this objective, a descriptive survey method was used together with a questionnaire that consisted of 4 axes to answer the central question: What are the factors affecting the choice of a major at the university? Results have shown that the item that measured the students’ ability to choose the major ranked (First); it was concerned with the effect on the students' choice of his/her major in the university. On the last position and with respect to this effect came the professional tendencies and desires. Results have also shown tha
... Show MoreThe purpose of the study is to identify the teaching techniques that mathematics' teachers use due to the Brain-based learning theory. The sample is composed of (90) teacher: (50) male, (40) female. The results have shown no significant differences between male and female responses' mean. Additionally, through the observation of author, he found a lack of using Brain-based learning techniques. Thus, the researcher recommend that it is necessary to involve teachers in remedial courses to enhance their ability to create a classroom that raise up brain-based learning skills.
أولاً : مشكلة البحث :
أن مشكلة البحث تتمثل بوجود حاجة لتحسين الطرائق والأساليب المتبعة في التدريس ولذلك اتجهت البحوث في مجال التربية وعلم النفس إلى تحديد طرائق التدريس المناسبة لتطوير التفكير.
ومن هذه الأساليب الحديثة العصف الذهني بوصفها من اكثر الطرق التي قد تؤدي إلى تحفيز الطلبة وأثاره القدرات الإبداعية لديهم في حقول التربية والتعليم وا
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While practicing of International business particularly that centered on foreign direct investment, let on one side, to achieving objectives of transnational corporations specially that represented in continuous pursue to improving its cash flows and maximization of stockholders wealth which is considered the most important objective to the transnational corporations, but in the same time its lead, on other side, to increasing the foreign exchange risk exposuring these corporations. So, the transnational corporations (TNCs) struggling to make strategies which are dealing in smart way, with this risk and its management in way that enable to avoiding risk comple
... Show MoreHuman Rights The word of graduation in the Arabic language to many meanings may be the most appropriate of what Al-Ragheb Al-Isfahani said in the right: is the coming of the thing from saying or doing at the time it must and in the form that must be, so the term human rights includes the following:First: A party has the right and another duty to.
This research aims at shedding light on the electronic disclosure of the financial information under the condition of the development of this kind of disclosure all over the world , and its effect on the job of auditing and accounting . It also aims to show the extent to which the observers of accounts are aware of their duties towards this kind of disclosure and to test the effect of some environment factors on the level of this awareness.
To achieve the aims of the research has been divided in to four parts. The first one deals with mathadolge of the research. The second parts is devoted to the theoretical aspect of the research referring to the notion of electronical, disclosure its features and effect on the auditing jo
... Show MoreIbn Hajar is one of historian who had a role in historical writing represented by his writings in those active participation in the Arab-Islamic civilization, particularly his approach to intellectual, and pictures of us in his book that's part of the intellectual heritage, but a line that was a key part of the book, any manuscript
A lot of researchers and specialists in language sciences have been agreed that Arabic language is on of living languages never disappear and keep pace with innovation and the challenges of the age and evolution civilization i.e any development in it’s connotations doesn't tzopped it (melted
الحديث عن محمد بن إسحاق النديم حديث عن عالم جليل كان له فضل تصنيف سفر خالد من أسفار المعرفة و العلم و سجل ضم عناوين ما أنتجته الأمة العربية الإسلامية في وقت عزها و مجدها و سطوع كوكبها في سماء الدنيا ، فجاء هذا الكتاب جامعا نافعا في بابه .
GIS is characterized by great potentialeties to deal with huge geographical data and conclude what is necessary for it. It was very useful to get use of the potentialities of this system of GIS in the field of archaeology and to harvest very accurate results in a relatively short time, compared to the old archaeological methods.