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%.
Ibn 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
After the fall of the Iraqi regime in the 9th of April 2003, and after the disintegration of the country, political and party political chaos that had never been witnessed before, has now taken over. In the past 2 years, the American military forces had a primary role in spreading this chaos and disorder by applying a set of wrong measures and policies. This chaos that is still affecting the iraqi people was completely ignored by the USA even 2 years after the occupation, no serious steps have been taken in order to bring back order and security, on the other hand, most of the government institutions and its forces were disintegrated, along with the decision made by Paul Bremer of dismissing all the iraqi journals and the workers of the
... Show MoreEmissions of particulate matter from nanopapers as well as inks and organic solvents during the printing operationand copying machines constitute a threat to human health, especially with long time exposure in closed working environments. The present study was conducted in some printing houses and copying centers of Baghdad city during February and April .The studyproved the occurrence of an air pollution problem concerning lead and zinc contents in all the study sites. The levels of Pb, Zn and Cu were collected by low volume sampler from the air of the study sites then filter papers digested and determined the heavy metals by flame atomic spectrophotometer. Particulate matter was measured by Aerocet, Microtector meter device was use
... Show MoreThis 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
... Show MoreAbstract
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.