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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. |
We found that 4,5- diphenyl- 3(2- propynyl) thio- 1??-triazole [1? forms a complex with Pd (11) ion of ratio 1:1 which absorbs light in CH2CI2 at 400 nm, and 4,5- diphenyl- 3(2- propenyl) thio- 1,2,4- triazole [II] forms complexes with Pd (II) ion of ratio 1:1 which absorbs light at 390 nm, and of ratio 2:1 which absorbs light at 435 nm. On the other hand, we found that the new derivative 4- phenyl- 5( p- amino phenyl) -3- mercapto- 1,2,4- triazole ?111? forms complexes with Cu (II) ion of the ratio 1:1 which absorbs light at 380 nm, with Ni (II) ion of the ratio 3:1 which absorbs light at 358 nm; and with Co (11) ion of the ratio 3.2:1 which absorbs light at 588 nm. The ratio of the complexes were determined by measuring the electronic spe
... Show MoreIn our time, not too long ago, the universities of the world have been fast to take care of the study of an innovative type of technical and human studies, called the science of "comparative literature". Comparative research studies have grown and flourished rapidly in response to the demands of both mental and artistic life. This shows the increasing awareness at both the modern national and the international levels in order to develop through connecting with the international intellectual, nental and artistic currents to nurture ethics and originality. Comparative studies show that the beginning of the comparative literature goes back to the time when the Latin literature was connected to the Greek literature and th
... Show MoreIndustrial effluents loaded with heavy metals are a cause of hazards to the humans and other forms of life. Conventional approaches, such as electroplating, ion exchange, and membrane processes, are used for removal of copper, cadmium, and lead and are often cost prohibitive with low efficiency at low metal ion concentration. Biosorption can be considered as an option which has been proven as more efficient and economical for removing the mentioned metal ions. Biosorbents used are fungi, yeasts, oil palm shells, coir pith carbon, peanut husks, and olive pulp. Recently, low cost and natural products have also been researched as biosorbent. This paper presents an attempt of the potential use of Iraqi date pits and Al-Khriet (i.e. substances l
... Show MoreSingle Point Incremental Forming (SPIF) is a forming technique of sheet material based on layered manufacturing principles. The sheet part is locally deformed through horizontal slices. The moving locus of forming tool (called as toolpath) in these slices constructed to the finished part was performed by the CNC technology. The toolpath was created directly from CAD model of final product. The forming tool is a Ball-end forming tool, which was moved along the toolpath while the edges of sheet material were clamped rigidly on fixture.
This paper presented an investigation study of thinning distribution of a conical shapes carried out by incremental forming and the validation of finite element method to evaluate the limits of the p
... Show MoreBackground: It's believed that HBD-3 is involved in the tissue remodeling process of articular cartilage. Also, HBD-3 has anti-inflammatory properties. Objectives: The purpose of this study is to assay human beta-defensine-3 (HBD-3) in serum from rheumatoid arthritis (RA) patients and investigate its correlation with proinflammatory cytokines. Methods: In this case-control study, fifty-eight RA patients were aged 20–65 years, and 29 age-matched healthy subjects (HS) had no inflammatory rheumatic diseases. The disease activity score-28 joint erythrocyte sedimentation rate (DAS28-ESR) was used to measure RA activity. CRP, ACPA, HBD-3, TNF-α, and IL-1β were assessed using the enzyme-linked immunosorbent assay technique (ELISA). Res
... Show MoreBackground: The study aimed to investigate the effect of different techniques of en masse retraction on the vertical and sagittal position, axial inclination, rate of space closure, and type of movement of maxillary central incisor. Materials and methods: A typodont simulation system was used (CL II division 2 malocclusion). Three groups were used group 1(N=10, T-loop), group 2(N=10, Time-Saving loop), and group 3(N=10, Microimplant). Photographs were taken before and after retraction and measurements were made using Autodesk AutoCAD© software 2010. Kruskal-Wallis one-way analyses of variance and Mann-Whitney U test (p?0.05) were used. Results: The rate of space closure showed no significant difference among the three groups (p?0.05), whi
... Show MoreThe present study took up the different ways to cultivate the species Epipremnum aureum by two habitat water and soil and comber the anatomical features of the root, stem, and leaf. The results showed amazing significant anatomical features to the ecosystem. The root and stem anatomy showing decrease in all characters that studied but the leaf anatomy showing increase of palisade, spongy tissue thickness, midrib thickness, number of vessels in the xylem also the long and width of stomata of the soilless plants than soil ones. The upper epidermis empty from the stomata for the two treatment and the stoma diffuse in the lower epidermis, the type of it paracytic type. Also the total of flavonoids in the plant that were growth in soil reached 1
... Show MoreMany attempts have been made to modify the surface of orthodontic micro-implants and prevent the development of microbes by coating them with antimicrobial nanoparticles (NPs). The purpose of the present study was to evaluate the cytotoxicity of different NPs, namely, TiO2 and zinc oxide (ZnO) NPs, that are used to coat titanium orthodontic micro-implants.
Thirty orthodontic micro-implants were included in this study. Those were divided into three groups: control group without coating, TiO2-coated orthodontic micro-implants, and TiO2- and ZnO-coated orthodontic micro-implants. Scann