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%.
Is to obtain competitive advantage legitimate objective pursued by all organizations to achieve, because they live today in environments of rapid change and dynamic in order to meet the demands of the customer changing as well as intense competition between the organizations, which requires them to get the location of competitive markets in order to do this will remain to do the building and strengthening competitive advantage to be able to achieve, but that this feature is not easy and is not only through the identification and use of a successful strategy for a competitive standard and then manage it successfully. Hence the research problem of determining the sources of differentiation strategy and its impact on the dimensions of compe
... Show MoreThe research included an introduction, and three functions
of the Prophet (peace and blessings of Allaah be upon him), a
machine and a companion, and a conclusion , the first function,
which is zakaah, and began with it because it is the basis of every
work, no work is accepted by Allaah except what was sincere to
him, as well as sincere intention, because accepting works is
entrusted with the
The study aimed to identify the E-leadership practice at Princess Nora Bint Abdul Rahman University and to explore the obstacles that are facing the leaders in the implementation of E-leadership, in addition to find mechanisms to improve the practice of electronic driving at the university in light of the Corona pandemic. A descriptive analytical approach was used by depending on a questionnaire to collect the needed data. The study sample consisted of (139) heads of departments, attorneys' colleges and support Deanships universities. The study results showed that E-leadership employment recorded a medium to high degree. Especially at university, that publishing decisions electronically and uses technical means in providing its services.
... Show MoreDie vorliegende Forschung erklärt ein sprachliches Phänomen im Deutschen und Arabischen, dessen Aspekte die Grund-Folge-Relation (Kausalität) im Allgemeinen sowie den wirkungslosen Gegengrund (Konzessivität) im Besonderen behandeln.
In diesem Kontext wird der Unterschied der verschiedenartigen Gründe der Kausalität im Deutschen, wie wirklicher Grund (kausal), möglicher Grund (konditional) und wirkungsloser bzw. unzureichender Gegengrund (konzessiv) gezeigt.
Die theoretischen Darlegungen der konzessiven Ausdrucksmittel in dieser Forschungsarbeit werden durch diverse praktische Beispiele aus der deutschen und arabischen Literatur fundamentiert.
Das Hauptziel dieser For
... Show MoreAbstract
The current research aims at identifying any of the dimensions of organizational learning abilities that are more influential in the knowledge capital of the university and the extent to which they can be applied effectively at Wasit University. The current research dealt with organizational learning abilities as an explanatory variable in four dimensions (Experimentation and openness, sharing and transfer of knowledge, dialogue, interaction with the external environment ), and knowledge capital as a transient variable, with four dimensions (human capital, structural capital, client capital, operational capital). The problem of research is the following questio
... Show MoreBasically, this study aims to identify the extent to which Iraqi secondary school students use writing strategies and how proficiency level and students gender could affect writing strategy use. The study also examines the relationship between writing achievement and writing strategy use among Iraqi secondary school students. For this purpose, 140 Iraqi secondary school students were selected randomly from six different schools. Petric and Czarl’s questionnaire (2003) was adopted in the study as an instrument to collect the needed data. A software of SPSS used to analyze the collected data. The findings revealed that secondary school students appeared as low users of writing strategies; low proficient students do not show a sta
... Show Moreتحيا الأمم بتراثها فهو الأساس الذي تنطلق منهُ، وما من أمة إلاّ ولها تراث، وهو سر حياتها وديمومتها ، فالأمة العربية الأسلامية لها تراث تليد التي تشرفت بحمل أقدس رسالة سماوية وأكملها لأمم الأرض، فكانت نبراساً أهتدت به البشرية حتى انتشلتها من واقعها المريض إلى أرغد عيش وأقوم خلق وأنبل نفس .
The importance of the topic lies in explaining the extent of Sheikh Abdul Qadir Al-Kilani’s interest in social and scientific life in Baghdad
التوجهات الفكرية الجديدة لانظمة دول العالم الثالث في ظل النظام العالمي الجديد : العراق نموذجاً
Resumen:
La traducción de los dos verbos ser y estar no es una tarea tan simple como piensan muchas personas, sino es una de las complicadas y difíciles tareas, ya que el traductor tiene que saber y perfeccionar los correctos casos gramaticales relacionados con esos dos verbos auxiliares tanto el verbo ser como el verbo estar, especialmente en la frase nominal para que pueda dar una clara y correcta traducción. Usados con el mismo adjetivo, "ser" comunicará una cualidad que es parte de la identidad o naturaleza del sujeto, mientras que "estar" comunicará un estado o circunstancia del mismo. Este e
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