The unsteady state laminar mixed convection and radiation through inclined
cylindrical annulus is investigated numerically. The two heat transfer mechanisms of
convection and radiation are treated independently and simultaneously. The outer
cylinder was kept at a constant temperature while the inner cylinder was heated with
constant heat flux. The study involved numerical solution of the governing equations
which are continuity, momentum and energy equations using finite difference method
(FDM), where the body fitted coordinate system (BFC) was used to generate the grid
mesh for computational plane. A computer program (Fortran 90) was built to calculate
the bulk Nusselt number (Nub) after reaching steady state condition for fluid Prandtl
number fixed at (Pr =0.7) (for air) with radius ratio ( =1.5, 2.6, 5.0), Rayleigh number
(0≤Ra≤103),Reynolds number (50≤Re≤2000), dimensionless heat generation (0≤Q≤10),
Conduction-Radiation parameter (0≤N≤10), optical thickness (0 ≤ t
≤ 10) and different
annulus inclination with horizontal plane (0°≤δ≤90°). For the range of parameters
considered, results show that radiation enhance heat transfer. It is also indicated in the
results that Nu increase with the increasing of inclination angle δ, Ra, Re, and Q. The
correlation equations are concluded to describe the radiation effect.
Comparison of the result with the previous work shows a good agreement.
One of the most important challenges facing the development of laser weapons is represented by the attenuation of the laser beam as it passed through the layers of atmosphere.This paper presents a theoretical study to simulate the effect of turbulence attenuation and calculates the decrease of laser power in Iraq. The refractive index structure C_n^2 is very important parameter to measure the strength of the atmospheric turbulence, which is affected by microclimate conditions, propagation path, season and time in the day. The results of measurements and predictions are based on the Kolmogorov turbulence theory. It was demonstrated by simulations that the laser weapons in Iraq were severely affected due to the large change in temperatures,
... Show MoreBackground: Even the wide use of dental implants, still there is a proportion of implants are failed due to infection. Much considerable attention has been paid to modify the implant surface. Coating of dental implant with a biocomposite material of suitable properties can improve osseointegration. And this is the main concern of this study. The aim of present study was to evaluate the use of a biocomposite coating of dental implant with (ceramic nano Al2O3 and metalic AgNo3) on the bond strength at bone – implant interface and tissue reaction. Materials and methods: A total number of forty-eight screws, CpTi dental implant used in this study. Half of these screws were coated with a biocomposite material of nano (Al2O3and AgNo3), thi
... Show MoreThe present study is carried out to identify the algae in the groundwater of the three areas of Tikrit city, including (the center of Tikrit , the region of AL-Jazira , Awainat village) by nine wells, a depths ranged between 9 meter at well 8 and 110 meter at wells 3 and 5 . And examined the environmental characteristics of physical, chemical and biological factors during the study period from September 2009 to June 2010. It is obtained that wells in the study area is lower alkalinity, average it ranged (6.448-7.418). It was noted that the values of the dissolved oxygen are few and almost non-existent in some cases it ranged between (6.5-6.3)mg/l , analysis of biological oxygen demand refers to wells water (clean- very clean) average
... Show MoreAllah Almighty has aggrandized the position of orphans and elevated their status in the society and has given the graces for those who sponsor the orphan and care for and protecting them, even those who rub their heads. The divine care is manifested in the verses of the Holy Bible and the Holy Quran. Therefore, the whole world cared for the orphan, and called for the rights of the orphans in the conferences and the channels. But all that was little effort that does not meet what the orphan need and some were only ink on paper that were not applied. All that mentioned above is necessary in dealing with the study (the rights of orphans in the Old Testament and Islam, a Comparative Study). The study was divided into a Preface and four inquirie
... Show MoreThe results of the current study showed that the thyroid gland in adult domestic cat (Felis catus) is located in the neck area on both sides of the trachea at rings (1-5). The gland consists of two lobes (right and left) and it is surrounded by a capsule of connective tissue consisting of two outer and inner layers, and a layer of fatty tissue overlaps with the outer layer of the capsule. In addition, the results of this study found that the histological structure of the thyroid gland is composed of several follicles that appear in different sizes and shapes; the follicles are lined with simple cuboidal epithelial tissue and sometimes appear lined with high and low simple cuboidal epithelial tissue. The gland is histologically composed of t
... Show MoreThis study was conducted in the Department of Employment and Loans at the Ministry of Labor and Social Affairs to indicate the importance and impact of both the empowerment and the functional flexibility in evaluating the performance of the employees. To achieve the objectives of the study, the data was collected through a questionnaire form designed for this purpose based on previous studies. Data obtained for a significant evaluation of the relationship between the components of both the empowerment and the functional flexibility with the components of the evaluation and determining the degree of importance of each component of both the empowerment and functional flexibility for the components of the evaluation by the extractio
... Show MoreThe present work was aimed to form the baseline data of normal morphological and histological structure features of liver in migratory starling (Sturnus vulgaris). Anatomically, the starling liver bird was dark red -brown in colour and located in the cranial third of the abdominal cavity and consisted of undivided lobes (left and right). The liver right lobe was larger than the left. Histological examination revealed that the liver parenchyma was covered by a connective tissue capsule which appears to be thicker in the rim of liver lobes than other area in the liver lobe. Liver parenchyma was arranged in an unlimited hepatic lobules, which composed of polygonal hepatocytes organized as irregular, radial interconnecting cords or laminae of o
... Show MoreGypsiferous soil deposits (Gypcrete) are weakly consolidate earthy mixture of secondary gypsum, sand and clay. It is formed in arid and semi- arid area with annual precipitation rainfall less than 400mm. These sediments occur in surface and subsurface in region of little rainfall and rapid evaporation. This research deals with the study of gypcrete in Alexandria to improve the mineralogical and geochemical properties of the gypcrete. The gypcrete soil is used as raw material to produce the plaster for building purposes. Three samples of gypcrete were chemically and geochemically analyzed. The common mineral is howed in 0-0.5m Gypsum followed by Calcite in 0-1m and Quartz in 1-1.5m due to leaching and infiltration by rainfall as well as it
... Show MoreIn this manuscript divide into two parts the first experimental and the second theoretical. The experimental part of polyvinyl chloride (PVC) can be used with aluminum (30%). Nanomaterials are synthesized by a laser pulse melting solution by ethanol. The effect of laser on the structural, morphological, optical, and electrical properties of nanoparticles (PVC) was examined by UV spectroscopy, x-ray diffraction (XRD), electron microscopy (TEM). The theoretical part of the DFT can be used to approximate the generalized gradient of the Perdew, Burke, and Ernzerhof (PBE) / 6-31G (d) groups, which were created using additional Gaussian 09 software through Gaussian 5.08. To build PVC nanocrystal pure which chemical formula [(C2H3Cl)n] and build (
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