An experimental and numerical study has been carried out to investigate the heat transfer by natural convection and radiation in a two dimensional annulus enclosure filled with porous media (glass beads) between two horizontal concentric cylinders. The outer cylinders are of (100, 82 and70mm) outside diameters and the inner cylinder of 27 mm outside diameter with (or without) annular fins attached to it. Under steady state condition; the inner cylinder surface is maintained at a high temperature by applying a uniform heat flux and the outer cylinder surface at a low temperature inside a freezer. The experiments were carried out for an annulus filled with
glass beads at a range of modified Rayleigh number (4.9 ≤ Ra≤ 69), radiation parameter (0<Rd<10), with fin length of (Hf=3, 7 and 11mm), with radius ratios of (Rr=(r1/r2) =0.1405,0.2045, 0.293 and 0.3649 ), number of fins (n=0, 12, 23 and 45). Finite difference method with Boussinesq's approximation is used to solve the continuity, energy and momentum equations.
The numerical solution is capable of calculating the streamline, the temperature field, the velocity field, the local and average Nusselt number. A computer program in Mat lab has been built to carry out the numerical solution. The numerical study was done for a range of modified Rayleigh number (4.9 ≤ Ra ≤ 300). Results show that the average Nusselt number is nearly constant for Ra less than 100 and increased with an increase in modified Rayleigh number.
Nusselt number hardly affected by glass beads size and insignificant affected by Rd for Ra less than 100. Decreasing Rr cause clearly increase in average Nusselt number and increasing fin length or fin number decrease heat transfer.
Because asceticism has a great impact on educating the human soul properly, according to what was mentioned in the Book and the Sunnah of the Prophet, and keeping it away from vices and what is devolving into it, and this world and its adornments keep the Muslim away from virtues and work with them in order to reach the Hereafter in which is the eternal bliss that God, peace be upon him, has prepared for the obedient. The two pious obedient ones. And because of the impact of this topic on the Islamic community and adorn it with good qualities. Likewise, I saw many Muslims who do not prefer the life of this world over the hereafter, and they began to fight over the world and enjoy its adornments, and they took pride in money, building, an
... Show MoreExtemporization is the ability of the actor to reflect his internal being. It gives a sort of confidence and an ability to show the personal countenance of the role away from tension and rigidity. By extemporization, it is possible to deal with and criticize the real living life so it is an intellectual, emotional, sensual, and perceptive process connected with the psychological energy and the emotional memory and all this goes under the control of the director and his instigations and instructions depending on what the text involves of intellectual, social and psychological motivators so it primarily depends on talent, chance and discussion. The research involves four chapters; the first contains the problem
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summary of the research
The heart is the pine-shaped flesh on the left side of the chest. The moral gentleness in this flesh is called the home of perception, reason and understanding, as well as the place of desires and passions, so it turns between one desire and another between good and evil. As for its parts, it consists of four main parts called chambers, two rooms on the right As for the two chambers below, it is called the ventricle, the heart works regularly and accurately to pump blood and distribute it to all parts of the body and vital organs. And the Holy Quran divided the types of heart into two main types of healthy hearts, which are types (healthy, hidden, living....)
And the second type is sick hea
... Show More The result of concentration varying of mixture methane with argon and neon gas are believed to study the change in electrons energy distribution function and then the change of the electrons transport parameters including the drift velocity, the mean energy, characteristics energy and diffusion coefficient. In the present work,a contemporary developed computer, simulation program known as Bolsig+ is being used for calculating the electron transport parameters.
Abstract: In this paper, a U-shaped probe with a curvature diameter of half a centimeter was implemented using plastic optical fibers. A layer of the outer shell of the fibers was removed by polishing to a D-section. The sensor was tested by immersing it in a sodium chloride solution with variable refractive index depending on solution concentrations ranging from 1.333 to 1.363. In this design, the sensor experienced a decrease in its intensity as the concentration of the solution increased. The next step The sensor was coated with a thin layer of gold with a thickness of 20 nm, and the sensor was tested with the same solutions which resulted in a shift in wavelengths where the shift in wavelength was 5.37 nm and sensiti
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Abstract of the research:
This research sheds light on an important phenomenon in our Arabic language, which is linguistic sediments, and by which we mean a group of vocabulary that falls out of use and that native speakers no longer use it, and at the same time it happens that few individuals preserve the phenomenon and use it in their lives, and it is one of the most important phenomena that It should be undertaken and studied by researchers; Because it is at the heart of our huge linguistic heritage, as colloquial Arabic dialects retain a lot of linguistic sediments, and we usually find them at all levels of language: phonetic, banking, grammatical and semantic. In the
... Show MoreIn this study, carbon nanotubes were prepared using a pure chemical method modified similar to the Hummers method with simple changes in the work steps. The carbon nanotubes were then coated and reduced on copper and aluminum metals using the electrodeposition method (EDP) for corrosion protection application in seawater medium (NaCl 3.5%) at four different temperatures: 20, 30, 40, and 50 °C, which were studied using three electrode potentiostats. All corrosion measurements, thermodynamics, and kinetics parameters were nominated from Tafel plots. The films deposited by the carbon nanotubes were examined by the SEM technique, and this technique showed the formation of carbon nanotubes.
This study includes applying chemical tests on cow, sheep and chicken bones including both hallow and flat. The results of chemical tests on bones mentioned the moisture percentage which was between 4.95-7.32 %, and it was noticed the difference in protein percentage among different kinds of bones, The highest protien percentage was 39.62 % in hallow chicken bones and the lowest was in hallow sheep bones 20.31%, at the same time, the highest Ash percentage was in hallow sheep bones48.11% , whereas the highest percentage of fat was in hallow cow bones 30%. The chemical and physical tests were conducted for extracted fat from hallow and flat bones for cows, sheeps and chicken. It was found that peroxide values (PV), and free fatty acids (F
... Show MoreAcute toxicity is a step to evaluate the toxicity of a substance. Rutin is one of the flavonoid compounds with a variety of pharmacological effects. The aim of the study is to calculate the lethal dose that affect fifty percent of the mice used in the experiment (LD50). Thirty Swiss albino male and 30 non-pregnant female mice have been divided equally and randomly into 5 treated groups and one control group (n=5) Rutin has been administered with concentrations 5, 2.5.1.25,0.625 and 0.312 g/kg administered as a single dose intraperitoneally (IP) while the control group received 1% DMSO (IP). Animals were observed for any morbidity and mortality for 14 days. After 14 days the animal blood collected for biochemical and hem
... Show MoreThis is a contextual study in face and isotope science, and I have made it in one of the terms faces and isotopes, which is the word (bad). Quranic also, and that is at every aspect they mentioned.
The nature of the research required that it be divided into three sections:
The first topic: I singled it out to show the types of contextual connotations.
- The second topic: I singled it out to define the word bad and its meaning.
- The third topic: I devoted it to the study of the word bad and explaining the significance of the Quranic context on the additional meaning and the original meaning.
Conclusion: It mentioned the most important results, which are:
1- The significance of the Quranic context is one of the most impo