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Experimental Study on the Effect of Insertion of Copper Lessing Rings in Phase Change Material (PCM) on the Performance of Thermal Energy Storage Unit
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Abstract

One of the most suitable materials to be used in latent heat thermal energy storage system (LHTES) are Phase change materials, but a problem of slow melting and solidification processes made many researchers focusing on how to improve their thermal properties. This experimental work concerned with the enhancing of thermal conductivity of phase change material. The enhancing method was by the addition of copper Lessing rings in phase change material (paraffin wax). The effect of diameter for the used rings was studied by using two different diameters (0.5 cm and 1cm). Also, three volumetric percentages of rings addition (3%, 6% and 10%) were tested for each diameter. The discharging process was done with four velocities for each case. The obtained results indicated that the maximum volumetric percentage gave a diminished time for melting and maximized the heat transfer in both PCM and air sides as compare with the case of no rings, but the effect of these rings had lower effect on the solidification time. In case of 1 cm rings diameter minimum time for melting was obtained for both 3% and 6% volumetric percentages as compared with the same percentages in case of 0.5 cm diameter rings, while the latter with 10% volumetric percentage overcomes the 1 cm diameter rings for the same previous percentage. Also it can be seen that the minimum velocity (v=1m/s) gave the utmost outlet temperature and with the maximum one (v=3m/s), the minimum solidification time achieved.

Keyword: Thermal energy storage systems, Latent heat storage, Phase change materials, Heat transfer enhancement.

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Publication Date
Mon Jan 01 2018
Journal Name
Journal Of The College Of Languages (jcl)
הסיפור העברי באמריקה ברבע השני של המאה ה-20 הסופר שמעון הלקין כדוגמה
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                                      הסיכום

          הסיפורת העברית באמריקה, הייתה קשורה בסביבה מסויימה. גם כן היא קשורה בנושאים מסויימים, ורובם היו מדברים על חיי היהודים באמריקה.

            דמותו של שמעון הלקין קבועה בנפשם של המבקרים כזו של משורר בעי

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Publication Date
Sat Dec 29 2018
Journal Name
Journal Of Planner And Development
اثر العامل الديني في تخطيط المدينة العربية والعمارة الاسلامية مدينة النجف الاشرف أنموذجاً
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Publication Date
Tue Dec 05 2023
Journal Name
Baghdad Science Journal
Indoor/Outdoor Deep Learning Based Image Classification for Object Recognition Applications
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With the rapid development of smart devices, people's lives have become easier, especially for visually disabled or special-needs people. The new achievements in the fields of machine learning and deep learning let people identify and recognise the surrounding environment. In this study, the efficiency and high performance of deep learning architecture are used to build an image classification system in both indoor and outdoor environments. The proposed methodology starts with collecting two datasets (indoor and outdoor) from different separate datasets. In the second step, the collected dataset is split into training, validation, and test sets. The pre-trained GoogleNet and MobileNet-V2 models are trained using the indoor and outdoor se

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Publication Date
Sat Jun 30 2007
Journal Name
Al-kindy College Medical Journal
Arthrogrypotic Club Foot
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Background: Arthrogryposis Multiplex congenita is a
rare disorder, characterized by multiple joint deformities
i.e. multiple congenital contractures, with shapelessly
cylindrical limbs and absent skin creases.
Club foot can be the only obvious deformity of this
widespread disorder.
Objective: To assess the most frequent recurrent
deformity after extensive soft-tissue release operations for
arthrogrypotic club foot and its appropriate treatment
regarding combined tendon transfer and bony operations.
Methods: A retrospective study of 14 patients with
arthrogrypotic club foot (28 feet), had been operated on by
multiple soft tissue and bony operations and followed in a
period between January (1993) till

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Publication Date
Tue May 16 2023
Journal Name
Journal Of Engineering
Natural Convection Heat Transfer from a Plane Wall to Thermally Stratified Environment
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The effect of linear thermal stratification in stable stationary ambient fluid on free convective flow of a viscous incompressible fluid along a plane wall is numerically investigated in the present work. The governing equations of continuity, momentum and energy are solved numerically using finite difference method with Alternating Direct implicit Scheme. The velocity, temperature distributions
and the Nusselt number are discussed numerically for various values of physical parameters and presented through graphs. ANSYS program also used to solve the problem. The results show that the effect of stratification parameter is marginalized with the increase in Prandtl number, and the increase in Grashof number does not practically vary the

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Publication Date
Sun Jun 12 2011
Journal Name
Baghdad Science Journal
Parabola Dish and Cassegrain Concentrators to Improve Solar Cell Conversion Efficiency
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New designs of solar using ray tracing program, have been presented for improved the performance and the out put power of the silicon solar cell, as well as reducing the cost of system working by solar energy. Two dimensional solar concentrator (Fresnel lenses) and three dimensional concentrators (parabola dish and cassegrain) were used as concentrator for photovoltaic applications (CPV). The results show that the performance efficiency and out power for crystalline silicon solar cells are improved.

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Crossref (1)
Crossref
Publication Date
Sun Jun 12 2011
Journal Name
Baghdad Science Journal
Hybrid(Luminescent and Fresnel ) Concentrators to Improve Solar Panel Conversion Efficiency
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The spectral response of the Si solar cell does not coincidence with the sun irradiance spectrum, so the efficiency of the Si solar cell is not high. To improve the Si solar cell one try to make use of most region of the sun spectrum by using dyes which absorb un useful wavelengths and radiate at useful region of spectrum (by stock shift). Fluorescence's dye is used as luminescent concentrator to increase the efficiency of the solar cell. The results show that the performance efficiency and out power for crystalline silicon solar cells are improved.

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Crossref
Publication Date
Sun Jan 01 2017
Journal Name
Journal Of The College Of Languages (jcl)
Traducción de los dos verbos auxiliares ser y estar del español al árabe en la frase nominal
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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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Publication Date
Tue Feb 14 2023
Journal Name
Journal Of Educational And Psychological Researches
Vocabulary Learning Strategies Employed by English as Foreign Language Students at NBU University
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ABSTRACT

Learning vocabulary is a challenging task for female English as a foreign language (EFL) students. Thus, improving students’ knowledge of vocabulary is critical if they are to make progress in learning a new language. The current study aimed at exploring the vocabulary learning strategies used by EFL students at Northern Border University (NBU). It also aimed to identify the mechanisms applied by EFL students at NBU University to learn vocabulary. It also aimed at evaluating the approaches adopted by EFL female students at Northern Border University (NBU) to learn a language. The study adopted the descriptive-analytical method. Two research instruments were developed to collect data namely, a survey qu

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Publication Date
Sun Jul 02 2017
Journal Name
Journal Of Educational And Psychological Researches
(دور الارشاد التربوي في محاربة المخدرات وتحقيق الامن النفسي من وجهة نظر المدرسين المرشدين )
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The research study aims to investigate the prevalence of the phenomenon of drags and the causes of this phenomenon from the teachers point  of view Two  hundred   Teachers  participated in this study Questionnaire  was used to  collect  the  data .                                 

The results emphasized the importance 0f the  educational  counseling  through  different  procedure  to prevent  drugs  abuse .   the results  also&

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