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%.
This research aims to measure the impact of applying bank governance mechanisms in reducing the financial risks of banks listed on the Palestine Stock Exchange, and to answer research questions and test hypotheses for the study, researchers adopted the descriptive and analytical approach, and data were collected from the annual financial reports of the banks listed on the Palestine Exchange during the period between (2009-2018), as a time series for the purpose of finding, analyzing and measuring the effect between the study variables during this period by (60) views for each of the study variables, using the statistical analysis program views(9) to enter, process and analyze the data. The results of the study proved that there i
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This research aim to overcome the problem of dimensionality by using the methods of non-linear regression, which reduces the root of the average square error (RMSE), and is called the method of projection pursuit regression (PPR), which is one of the methods for reducing dimensions that work to overcome the problem of dimensionality (curse of dimensionality), The (PPR) method is a statistical technique that deals with finding the most important projections in multi-dimensional data , and With each finding projection , the data is reduced by linear compounds overall the projection. The process repeated to produce good projections until the best projections are obtained. The main idea of the PPR is to model
... Show MoreThe success of any work requires the development of prior plans for the success of this work as well as providing the necessary sources of funds for the implementation of those plans, where the start of the research problem of delayed sending project proposals to the Ministry of Planning to do its job oversight in checking the technical and economic of those projects feasibility studies, has sought the researcher to the statement of need activating the role of the Ministry of planning in the study of projects before they are implemented and the trade-offs between important projects and projects the most important as they related to the usefulness of the community as well as the economic feasibility evaluation of them in terms of providin
... Show Moreمما توصل إليه البحث :
إن الدوافع النفسية تنفرد في تجسيد الأحاسيس والمشاعر في نتاج الشاعر , من خلال رؤيته لتلك الحالة , فتسهم في صورة المقارنة في التشبيه , فتبعث في المتلقي حالة التأمل والمقارنة بين الحالتين اللتين تجمع بين مكوناتهما صفة واحدة فتصل إلى حالة التلاحم , ويكون ذلك باعثا لرسم صورة التشبيه ال
... Show MoreOur research, entitled(Population and economic determinants of society and its impact in the history of contemporary Baghdad 1940-1960), dealt with a number of historical facts and events of the social, demographic and economic
This research has been devoted to the study narratines of the metaphysical concepts in Egypt during the Mamluk era ( 648-923 AD/1250-1517 AH). The study consists of three sections and an introductionwhich highlights the study at that time for its great impaction public life in Egypt.
This research shows the issues of Ibn Hisham's illusion in its leadership of the grammarians; As Ibn Hisham attributed - during his presentation of grammatical issues - grammatical opinions to a number of grammarians claiming them in them, and after referring to the main concepts that pertain to those grammarians, we found that Ibn Hisham had delusional in those allegations, in addition to that clarifying the terms illusion and claim in the two circles of language And the terminology, and perhaps the most prominent result in this research is that he worked to investigate these issues by referring to their original sources, with an explanation of the illusions of Ibn Hisham in his attribution to these issues.
The literature in general, such as the spanish literature as british literature presence lot of literary figures giant that managed its continuing work that leaves lasting impression and clear in all fields of literary world throughout history, among these writers giants can remind great writer spanish (Miguel de Cervantes) and the great british writer (William Shakespeare), this study is about them.
We can say that there are a lot of studies , works and gossip , whether literary or non- literary show how the close relationship that bound both Cervantes and William Shakespeare, although they did not meet personally never, it was not able to critics that the sweep of the differences and similarities that was between the two, becau
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The factor that keeps society from collapsing and regressing to chaos, violence, and lawbreaking is to stick to the human moral principles and criteria of moral behavior that prevent the spread of corruption and crime to the extent that law becomes devoid of activity and loss its dot errant power in front of chaos. The role of moral behavior is to motivate individuals to respect the general laws in dealing with others. Because of the dissemination of odd behavior patterns within our society, the social links are been badly affected and it's urgent for educational institutions to perform their duty in working on spreading awareness about moral values and avoid deviant directions and socially threatening t
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