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Natural convection in an annular space provided with metal foam fins attached to the inner cylinder is studied numerically. The metal foam fins made of copper were inserted in different axial sections with three fins in each section. The temperature of the inner cylinder is kept constant while the annular outer surface is adiabatic. The thickness effect of the inner pipe wall was considered. Naiver Stokes equation with Boussinesq approximation is used for the fluid regime while Brinkman-Forchheimer Darcy model is used for metal foam. In addition, the local thermal non-equilibrium condition in the energy equation of the porous media is presumed. The effect of Rayleigh number and number of foam fins in the axial direction, on fluid flow and heat transfer characteristics, were examined. The current model was valid with the available published results and good agreement is noticed. Results showed that as the Rayleigh number increases the dominated of convection mode increases and average Nusselt increases. It was found that at Rayleigh of 106 Nusselt reached its higher value which is 4.6 for the case of adding seven axial metal foams. A comparison between adding foam fins and copper fins was established for a range of Rayleigh numbers between 104 and 106. It showed a good enhancement in Nusselt number and the greatest enhancement percentage was 45.9% at Rayleigh equal 106 for the case of using seven sections of foam fins. |
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Background: Repeated blood transfusion is the main therapeutic option for transfusion-dependent anaemias with consequent iron overload and organ damage .Therefore iron chelating agents are important protective measures for these patients. The aim of this study was to investigate the efficiency and safety of Desferroxamine in paediatrics population subjected to iron overload as a consequence of repeated transfusion in a group of Sudanese children Subjects & Methods: This was a descriptive cross-sectional hospital based study. Conducted in two main paediatric reference hospitals in, Su |
Objectives: Although the Frankfort Horizontal (FH) and sella-nasion were routinely used as craniofacial reference planes, the inter-individual orientations were changeable when related to true horizontal (HOR). Natural head position (NHP) is a reproducible, standardized position, with the head in an upright posture and eyes focused on a point in the distance at eye level so that the visual axis is horizontal. The natural head position has importance in anthropological as well as in orthodontic fields, as this position has a relatively fixed relationship to the true horizontal and vertical planes. However, NHP is clinically not simple and it takes long time to be recorded, in addition to a deficiency in the tools utilized in the NHP and l
... Show MoreNew complexes of the [M(Ura)(Phen)(OH2)Cl2]Cl.2H2O type, where (Ura) uracil ; (Phen) 1,10-phenanthroline hydrate; M (Cr+3 , Fe+3 and La+3) were synthesized from mix ligand and characterized . These complexes have been characterized by the elemental micro analysis, spectral (FT-IR., UV-Vis, 1HNMR, 13CNMR and Mass) and magnetic susceptibility as well the molar conductive mensuration. Cr+3, Fe+3 and La+3- complexes of six–coordinated were proposed for the insulated for three metal(III) complexes for molecular formulas following into uracil property and 1,10-phenanthroline hydrate present . The proposed molecular structure for all metal (III) complexes is octahedral geometries .The biological activity was tested of metal(III) salts, liga
... Show MoreNew complexes of the [M(Ura)(Phen)(OH2)Cl2]Cl.2H2O type, where (Ura) uracil ; (Phen) 1,10-phenanthroline hydrate; M (Cr+3 , Fe+3 and La+3) were synthesized from mix ligand and characterized . These complexes have been characterized by the elemental micro analysis, spectral (FT-IR., UV-Vis, 1HNMR, 13CNMR and Mass) and magnetic susceptibility as well the molar conductive mensuration. Cr+3, Fe+3 and La+3- complexes of six–coordinated were proposed for the insulated for three metal(III) complexes for molecular formulas following into uracil property and 1,10-phenanthroline hydrate present . The proposed molecular structure for all metal (III) complexes is octahedral geometries .The biological activity was tested of metal(III) salts, ligands
... Show MoreAlthough renewable energy systems have become an interesting global issue, it is not continuous either daily or seasonally. Latent heat energy storage (LHES) is one of the suitable solutions for this problem. LHES becomes a basic element in renewable energy systems. LHES compensate for the energy lack when these systems are at low production conditions. The present work considered a shell and tube LHES for numerical investigation of the tube rotation influence on the melting process. The simulation and calculations were carried out using ANSYS Fluent software. Paraffin wax represents the phase change material (PCM) in this work, while water was selected to be the heat transfer fluid (HTF). The calculations were carried o
... Show MoreNew polydentate ligand namely bis(N-carboxylatoethyl)-0,0`-dipyridinium) L was synthesised from the reaction of 0,0`-dipyridine with ethyl chloropropionate. Polymeric complexes of general formulae [Cr2(L)(N3)0]Cl2.H2O, Na2[Ag2(L)(N3)0].H2O and [M2(L)(N3)0].nH2O, where (M= Mn(II), Fe(II), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II); (where n = 2;1;1;1;4;1 and 1, respectively)) are reported. The mode of bonding and overall geometry of the complexes were determined through physico-chemical and spectroscopic methods. These studies revealed octahedral geometry complexes. Molecular structure for the complexes has been optimised by CS Chem 3D Ultra Molecular Modelling and Analysis Program and supported a six coordinate geometry.
The population studies are one of the difficult tasks facing the world in all periods. most of the researchers and who have relationship to population policies and development plans, may have succumbed to the idea that the population problem is based and confined mainly in the rate of increase in population, or the so – called population explosion, and not the content because of its pressure on resources and there is no problem of population if the resources are available and therefore no need for the development and implementation of population policies in any way . While the population policies here should take a range of general and comprehensive in every respect to population and demographic phenomena distribution, not only
... Show MorePhotoacoustic is a unique imaging method that combines the absorption contrast of light or radio frequency waves with ultrasound resolution. When the deposition of this energy is sufficiently short, a thermo-elastic expansion takes place whereby acoustic waves are generated. These waves can be recorded and stored to construct an image. This work presents experimental procedure of laser photoacoustic two dimensional imaging to detect tumor embedded within normal tissue. The experimental work is accomplished using phantoms that are sandwiched from fish heart or blood sac (simulating a tumor) 1-14mm mean diameter embedded within chicken breast to simulate a real tissue. Nd: YAG laser of 1.064μm and 532nm wavelengths, 10ns pulse duration, 4
... Show MoreThe Results Of Interest In Capitals And Major Cities Have Become Major Attraction Centers For People In Rural Areas And Different Regions, Especially With The Concentration Of Industrial And Commercial Establishments And Public Services, Which Helped To Find The Wide Differences Between Them. Recently, The Trend To Develop Small Urban Centers In Rural Back Areas Great And Serious Attempt To Reduce Inflation. The Suburb Of Abu Ghraib Is One Of The Important Suburbs Near The City Of Baghdad And Through The Study Of The Reality Of The Suburb Shows That The Outcome Of Its Career And Urban Development Lies In Its Mutual Relationship With The City Of The Mother In The Light Of Considerations And Measures Of The Most Important Accessibility And
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