This thesis studied the finite element modeling of plane wave acoustic phenomena in ducts. The study looked into finite element factors such as shape functions, mesh refinement, and element distortion. The study concluded that the higher order shape function eight-node quadrilateral element gave considerably better results than lower order shape function four-node quadrilateral element. The eight-node element converged much faster to the analytical solution than the four-node element. The average error, taking all the cases in consideration, for the four-node element was around 30 % for a mesh refinement of about 14 elements per wavelength at 100 Hz frequency. The eight-node element in the other hand had average absolute errors of less than 1% under the same conditions. This section also found that the eight-node element was substantially more resistant to solution deterioration due to element distortion than the four-node element. For example distorting the four-node element up to 60* degrees usually increased errors very rapidly to above 100 % errors. The eight-node element on the other hand usually produced errors of less than 5 % for the same level of distortion. The study showed that the type of boundary condition used had a significant effect on the solution accuracy. The study demonstrated that the effect of the natural boundary conditions was more global. Meeting this kind of boundary condition through mesh convergence produced accurate results throughout the duct. / Master of Science

No description available.

published_or_final_version / Medical Sciences / Master / Master of Medical Sciences

No description available.

Inter-turbine diffusers or swan neck ducts (SND's) provide flow continuity between the H.P. and L.P. turbine, which with diffusing of the flow allow; greater stage efficiencies to be achieved as a consequence of reducing both the stage loading and flow coefficient of the L.P. turbine. This thesis presents an experimental and computational investigation into the local flow development and overall performance of two different severity diffusing annular sshaped ducts, with the same overall diffusion ratio of 1.5, in order to validate the CFD code M.E.F.P. The first less severe diffusing duct was used to investigate the effects of inlet swirl on the duct performance. It was found that at an optimum swirl angle of 15 degrees, the duct total pressure loss coefficient was approximately half the value at 0 or 30 degrees swirl. The second more severely diffusing duct had simple symmetrical aerofoil struts added, which simulated struts required in real inter-turbine diffusers to support inner shafts and supply vital engine services. The total pressure loss developed by the 30% shorter duct was 15% greater that of the longer duct, and when struts were added to the second duct the loss almost doubled. These increases were attributed to gradually worsening casing surface flow separations which also acted to reduce the overall static pressure recovery of the ducts as their losses increased. The computational investigations were made on the more severe duct with and without struts. The code, Moore's Elliptic Flow Solver (M.E.F.P) which used a mixing length model, predicted flow separation in the strutted duct case albeit in slightly the wrong position, however, it failed to predict any secondary flow for the unstrutted case and hence correlated worse with the measured results. This was also true of the results predicted by a version of Dawes BTOB3D.

Thesis (M.S.)--West Virginia University, 2007. / Title from document title page. Document formatted into pages; contains v, 44 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 39-40).

Thesis (Ph. D.)--West Virginia University, 2006. / Title from document title page. Document formatted into pages; contains ix, 77 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 75-77).

Thesis (M.S.)--West Virginia University, 2006. / Title from document title page. Document formatted into pages; contains xi, 97 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 62-63).

Abstract Carbonic anhydrases (CAs) are a group of zinc-containing metalloenzymes that catalyze the interconversion of carbon dioxide and bicarbonate (CO2 + H2O ⇔ HCO3- + H+). They are present in almost all organs and are implicated in various biological functions, the most important of which is participation in the regulation of ion, water, and acid-base balance. Recently, some members of the CA gene family have been suggested to promote cell proliferation and to act as trophic growth factors. The present study was undertaken to examine the distribution of CA isoenzymes in the reproductive system, to attain a more detailed view on their linkage to the reproductive processes and to neonatal development. The expression of membrane-bound CA IX and CA XII was studied in the female and male reproductive tracts by immunohistochemistry and western blotting. CA XII was found to be expressed in the basolateral plasma membrane of luminal and glandular epithelia in human uterus. In human efferent ducts, it was located in the basolateral plasma membrane of luminal epithelium, where it coexpressed with Aquaporin-1. In epididymal duct, CA XII was only expressed in occasional epithelial cells. These cells coexpressed CA II, suggesting that they represent apical mitochondria-rich cells (AMRC). CA IX was also expressed in the basolateral plasma membrane of luminal epithelium in human efferent ducts, but its expression was not uniform among the tubules. These findings suggest that basolateral plasma membrane-associated CA IX and CA XII contribute, along with CA II and CA IV, to the regulation of acid-base balance and water transport in the reproductive tract. Western blotting of rat Leydig tumor cells and testis for CA II revealed an unidentified 66-kDa polypeptide band. The polypeptide was successfully purified from several rat tissues using CA inhibitor affinity chromatography. The amino acid sequence of the polypeptide showed it to be identical to NonO/p54nrb, a non-POU domain-containing octamer-binding protein previously implicated in transcriptional regulation. The recombinant NonO/p54nrb was shown to display CA activity, and the antibody to it predominantly immunostained the nuclei in lymphocytes, where CA activity was also detected histochemically. Accordingly, the nuclear Leydig cell CA immunoreactivity represents NonO/p54nrb. It is classified as a novel, nonclassical CA, and it may participate in pH-related events in the nucleus. Human and rat milk was found to contain CA VI by immunohistochemistry and western blotting. The enzyme purified from human milk by CA inhibitor affinity chromatography was confirmed by PNGase F digestion and amino acid sequence as CA VI. The CA VI concentrations in human colostral milk were approximately eight times higher than those in mature milk (34.7 mg/l vs. 4.5 mg/l). Secretion of CA VI into milk is suggested by its localization in the alveolar epithelium of the rat mammary gland. The structural and functional stability of CA VI in an acidic milieu, its suggested growth-supporting function in taste bud stem cells, and its high concentration in colostrum suggest that it is an essential factor for the growth and development of the newborn alimentary canal.

No description available.