Component-adaptive grid embedding

One of the major problems related to transonic flow prediction about realistic aircraft configuration is the generation of a suitable grid which encompasses such configurations. In general, each aircraft component (wing, fuselage, nacelle) requires a grid system that is usually incompatible with the grid systems of the other components; thus, the implementation of finite-difference methods for such geometrically-complex configurations is a difficult task. An approach was developed to treat such a problem. The basic idea is to generate different grid systems, each suited for a particular component. Thus, the flow field domain is divided into overlapping subdomains of different topology. These grid systems are then interfaced with each other in such a way that stability, convergence speed and accuracy are maintained

A Computer Program for the Calculation of Three-Dimensional Transonic Nacelle/Inlet Flowfields

A highly efficient computer analysis was developed for predicting transonic nacelle/inlet flowfields. This algorithm can compute the three dimensional transonic flowfield about axisymmetric (or asymmetric) nacelle/inlet configurations at zero or nonzero incidence. The flowfield is determined by solving the full-potential equation in conservative form on a body-fitted curvilinear computational mesh. The difference equations are solved using the AF2 approximate factorization scheme. This report presents a discussion of the computational methods used to both generate the body-fitted curvilinear mesh and to obtain the inviscid flow solution. Computed results and correlations with existing methods and experiment are presented. Also presented are discussions on the organization of the grid generation (NGRIDA) computer program and the flow solution (NACELLE) computer program, descriptions of the respective subroutines, definitions of the required input parameters for both algorithms, a brief discussion on interpretation of the output, and sample cases to illustrate application of the analysis

A grid-embedding transonic flow analysis computer program for wing/nacelle configurations

An efficient grid-interfacing zonal algorithm was developed for computing the three-dimensional transonic flow field about wing/nacelle configurations. the algorithm uses the full-potential formulation and the AF2 approximate factorization scheme. The flow field solution is computed using a component-adaptive grid approach in which separate grids are employed for the individual components in the multi-component configuration, where each component grid is optimized for a particular geometry such as the wing or nacelle. The wing and nacelle component grids are allowed to overlap, and flow field information is transmitted from one grid to another through the overlap region using trivariate interpolation. This report represents a discussion of the computational methods used to generate both the wing and nacelle component grids, the technique used to interface the component grids, and the method used to obtain the inviscid flow solution. Computed results and correlations with experiment are presented. also presented are discussions on the organization of the wing grid generation (GRGEN3) and nacelle grid generation (NGRIDA) computer programs, the grid interface (LK) computer program, and the wing/nacelle flow solution (TWN) computer program. Descriptions of the respective subroutines, definitions of the required input parameters, a discussion on interpretation of the output, and the sample cases illustrating application of the analysis are provided for each of the four computer programs

Three dimensional steady and unsteady asymmetric flow past wings of arbitrary planforms

The nonlinear discrete vortex method was extended to treat the problem of asymmetric flows past a wing with leading-edge separation, including steady and unsteady flows. The problem was formulated in terms of a body-fixed frame of reference, and the nonlinear discrete vortex method was modified accordingly. Only examples of flows past delta wings are presented. Comparison of these results with experimental results for a delta wing undergoing a steady rolling motion at zero angle of attack demonstrates the superiority of the present method in obtaining highly accurate loads. Numerical results for yawed wings at large angles of attack are also presented. In all cases, total load coefficients, pressure distributions and shapes of the free-vortex sheets are shown

Unsteady flow past wings having sharp-edge separation

A vortex-lattice technique is developed to model unsteady, incompressible flow past thin wings. This technique predicts the shape of the wake as a function of time; thus, it is not restricted by planform, aspect ratio, or angle of attack as long as vortex bursting does not occur and the flow does not separate from the wing surface. Moreover, the technique can be applied to wings of arbitrary curvature undergoing general motion; thus, it can treat rigid-body motion, arbitrary wing deformation, gusts in the freestream, and periodic motions. Numerical results are presented for low-aspect rectangular wings undergoing a constant-rate, rigid-body rotation about the trailing edge. The results for the unsteady motion are compared with those predicted by assuming quasi-steady motion. The present results exhibit hysteretic behavior

Intrahepatic expression of interferon alpha & interferon alpha receptor m-RNA can be used as predictors to interferon response in HCV and HCC patients

Chronic hepatitis C Virus (HCV) is the leading cause of liver cirrhosis worldwide and in Egypt. Patients with cirrhosis secondary to chronic HCV infection are at increased risk for developing Hepatocellular carcinoma (HCC) in which Interferon therapy is the only effective anti-viral therapy. The current study aimed to investigate the expression IFN-αand IFN-αReceptor genes in liver biopsies from patients with HCV and HCC. Correlation of their expression with the clinical, histopathological progress of the disease and the effectiveness of IFN therapy in HCV patients after a period of 6 months follow-up was done. Expression of IFN-α and IFNα-Rc m-RNA was investigated by RT-PCR using liver biopsy specimens from 30 HCV patients including 7 patients complicated with HCC. Liver biopsies were also subjected to formalin fixation for complete histopathological examination. Ninety seven percent of patients expressed Interferon Alpha m-RNA while 30% only expressed Interferon Alpha Receptor m-RNA. Responders and non-responders to Interferon therapy were divided according to their HCV RNA after six-months follow up period of interferon therapy. Responders showed significantly lower mean age, better histopathological states and higher incidence of expression of IFN Alpha Receptor mRNA. Regardless of the response to interferon, histological activity index scores and the degree of fibrosis showed a significant inverse correlation to the presence of IFNα-R m-RNA. IFNα-R mRNA expression decreases with the histological progress of the disease, suggesting that lower expression of the IFNα-Rc may be partially responsible for the unfavorable response to interferon in these patients. African Journal of Health Sciences Vol. 14 (1-2) 2007: pp. 86-9

Commonwealth Professional Fellowship: the wealth of experience and lessons learned.

The Commonwealth Professional Fellowship (CPF) is a programme of the Commonwealth Scholarship Commission in association with the British Council. The Fellowship is aimed at providing a professional development opportunity for mid-career professionals from Commonwealth developing countries in diverse disciplines. Fellows who take part in this programme spend a period of one to three months in the United Kingdom to keep abreast of current trends and developments, and receive training in appropriate fields

Challenges with Reference Citations among Postgraduate Students at the Kwame Nkrumah University of Science and Technology, Kumasi, Ghana

Referencing or citing sources a writer uses is an important part of academic writing. It allows the writer to acknowledge the ideas or words of others used in his/her work and avoid plagiarism. Referencing also demonstrates that the writer has read relevant background literature and can provide authority for statements made. Proper citation allows others to locate the materials used. The researchers’ experience while working on the Kwame Nkrumah University of Science and Technology (KNUST) Institutional Repository brought to the fore challenges postgraduate students encounter in citing references in their academic work. These include poor citing of reference works, inconsistencies in reference citation, use of different citation styles in theses submitted to the repository from the same department among others. Questionnaires and interview methods were employed. Five hundred and six questionnaires were distributed representing ten percent of the total population of postgraduate students of KNUST. Information sought in the questionnaire included students’ biographical data, mode of assessment, departmental referencing format, knowledge of reference style formats, students’ confidence in citing references and faculty’s perception about the way students cited references. This paper seeks to identify and discuss some of the challenges KNUST postgraduate students face in their academic writing. The study found out that KNUST postgraduate students have problems in mastering reference style formats because of the variations in citation. Students tend to rely on books, lecturers or librarians for assistance in ensuring the accuracy of citations they use in their work. Students were not able to identify the citation format they used; they could not cite references for books and journal articles with confidence. Among the recommendations made were that, librarians should play a wider role in the arena of academic integrity, faculty and librarians should collaboratein teaching students about reference citation formats used in academia. College librarians should advocate for the standardization on reference styles in their various colleges. Library orientation given by librarians should be replaced with Information Literacy skills to be offered to students in the first and final years.Keywords: Documentation Styles, Citation, Bibliographic, KNUS