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 subject of disclosure, transparency and corporate governance taking globally significant attention recently, especially after the collapse of many large companies because the level of disclosure and transparency is an important measure of the effectiveness and reliability of the system of governance in the companies, the equity in the provision of correct information and clear and complete in a timely manner to all stakeholders in the life of the company with whom in relation strengthen the confidence the company's management systems and automatic guide the staff and the decision-making.
The research aims to shed light on the concept of corporate governance, and the reasons and motives of the spread
مستخلص البحث أهمية البحث عن طريق إعداد برنامج تدريبي يعتمد هذه الطريقة التدريبية في تطوير التحمل الخاص عن طريق العمل على بناء مستوى جيد من التحمل الخاص لدى اللاعبين الشباب في مرحلة الإعداد الخاص, تحقيق نتائج جيدة على مستوى أداء الواجبات المهارية والخططية المطلوبة منه في أثناء زمن المباراة, حيث ارتأت الباحثة من خلال إعداد برنامج تدريبي إلى رفع مستوى (التحمل الخاص) لدى لاعبي كرة القدم وبالتالي يمكنها أن تساع
... Show MoreThe research aims to highlight on the behavioural approach in accounting, and clarify the behavioural implications of the main activities of accounting, and clarify the concept of information inductance within the framework of the behavioural approach and its impact on preparing financial statements. And that the impact of financial information on the behaviour of investment decision-makers, and to achieve the goals of the research, the researcher prepared a questionnaire according to Likert five-step scale, and he took into consideration in preparing it in line with the characteristics of the study community, and that the target community for this questionnaire is the investors in the Iraq Stock Exchange. The researcher reached
... Show MoreThat the government sector takes a big place in the countries and represents a significant role in the face of challenges and adaptation to the important and necessary changes that occur today, including the use of electronic. The electronic computer is a requirement of modern technology in various fields of science, including accounting, Because it derives its entity and content from the spirit of society and its mentality in all its branches, especially the subject of the research system of government accounting Because of its impact on the planning and financial implementation, especially in the preparation and implementation of the State budget, along with expenditure and revenue. Addressing tells us that the first of the sear
... Show MoreThe study aims to test the relationship of work pressure to its dimensions (role conflict, ambiguity of role, workload and nature of work) as an independent variable and its effect on organizational alienation by its dimensions (disability, lack of power, indifference, animosity, social isolation and self-alienation) (Restraint and confidence in negation, initiative, adaptation and living conscience) as a mediator variable, in some faculties of Baghdad University of Science (Medicine and Engineering) and Humanity (Education and Literature). The data was collected on the practical side, which was applied randomly (306) of the teachers and teachers of the colleges (56) items, which included the main research variables
... Show MoreThe aim of this study is know the five leadership practices according to the theory of network of leadership by Black and Mouton for the presidents of the Taxation General Board from their prospective, that is through answering the questionnaire questions. To achieving the objectives of this study, the researcher organized a questionnaire form as a main instrument for data collection. It includes (30) items distributed into five leadership practices according to the theory of network of leadership. Each one is subdivided into (6) questions.
The questionnaire was distributed to the presidents of the Taxation General Board of (14). The researcher used the SPSS program to analyses the answers. Through the answers, h
... Show Moreيهدف البحث الحالي التعرف على اسباب السرقة لدى تلاميذ المرحلة الابتدائية كما يراها معلموهم ومعلماتهم ، وعن الاساليب المتبعة في معالجة ظاهرة السرقة من قبلهم ، ولقد شملت عينة البحث على ( 200 ) فرداً من معلمي ومعلمات تلاميذ المرحلة الابتدائية في مدينة المكلا للعام الدراسي ( 2004 ـ 2005 ) ، وقد استخدمت الباحثة استبياناً أعدته كأداة للوصول الى اهداف البحث بعد ان تم التأكد من صدقه وثباته ، استخدمت الباحثة معادلة ارتب
... Show MoreThis research is important because of the importance of the subject matter and the implications for the future of development in Iraq. This requires linking the accounting systems with the economic developments. The accounting system we will address in this research is the cost accounting system and its role in determining value added tax. The value added tax and the extent of the relationship with the general accounting principles of cost accounting through which the value added is determined provided the use of a sound and effective cost system.
The problem of research was about knowing the role of cost accounting in determining the value added
... Show MoreThe present study aims at empirically investigating the effect of vocabulary learning strategies on Iraqi intermediate school students’vocabulary performance and reading comprehension. The population of the present study includes all the 1st year male students of Al-Wark’a intermediate school of Al-Risafa 1/ General Directorate of Education for the first course of the academic year (2015-2016). To achieve the aim of the study ,a pre-test and post-test after (5) weeks of experiment are administrated .The sample of the present study consists of (100) subjects :(50) students as an experimental group and other (50) students as a control group . The subj
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