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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Software quality journal 1 (1992), S. 81-100 
    ISSN: 1573-1367
    Keywords: education ; measurement ; metrics ; models ; goal oriented approach ; data collection ; data analysis ; measurement programme
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract This paper deals with a perceived need for a well-balanced education (or in some cases re-education) in the subject of software engineering measurement, more commonly although less accurately known as software metrics. This need was confirmed by a major survey of both industry and academia conducted in 1989. Software metrics have received a lot of bad press in the past, mainly due to some much criticized early work in so-called complexity metrics. A result of this has been scepticism or lack of interest in other areas of the wider subject of software engineering measurement, which covers not only models and measures applicable to software products, but also those applicable to the processes and resources involved in software production. The ideas and work described in this paper have arisen out of the ESPRIT project ‘METKIT’, which has produced educational material about software engineering measurement for use in both industry and academia. This paper also describes the material designed for academia, most of which has now been tested in 12 European academic institutions. The material concentrates on principles and examples rather than prescribing the use of particular models and measures. This material has been widely publicized; the response to it has been encouraging so far and it appears that the material will have a significant impact towards getting the subject taught much more widely, and in a more balanced way.
    Type of Medium: Electronic Resource
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  • 2
    Publication Date: 2011-08-24
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft (ISSN 0021-8669); 29; 4, Ju; 565-574
    Format: text
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  • 3
    Publication Date: 2011-08-19
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft (ISSN 0021-8669); 28; 609-617
    Format: text
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  • 4
    Publication Date: 2013-08-31
    Description: An overview of the computational effort to analyze forebody tangential slot blowing is presented. Tangential slot blowing generates side force and yawing moment which may be used to control an aircraft flying at high-angle-of-attack. Two different geometries are used in the analysis: (1) The High Alpha Research Vehicle; and (2) a generic chined forebody. Computations using the isolated F/A-18 forebody are obtained at full-scale wind tunnel test conditions for direct comparison with available experimental data. The effects of over- and under-blowing on force and moment production are analyzed. Time-accurate solutions using the isolated forebody are obtained to study the force onset timelag of tangential slot blowing. Computations using the generic chined forebody are obtained at experimental wind tunnel conditions, and the results compared with available experimental data. This computational analysis compliments the experimental results and provides a detailed understanding of the effects of tangential slot blowing on the flow field about simple and complex geometries.
    Keywords: AERODYNAMICS
    Type: NASA. Dryden Flight Research Center, Fourth High Alpha Conference, Volume 3; 22 p
    Format: application/pdf
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  • 5
    Publication Date: 2011-08-24
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft (ISSN 0021-8669); 28; 689-699
    Format: text
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  • 6
    Publication Date: 2019-06-28
    Description: The flow over multi-element airfoils with flat-plate lift-enhancing tabs was numerically investigated. Tabs ranging in height from 0.25 percent to 1.25 percent of the reference airfoil chord were studied near the trailing edge of the main-element. This two-dimensional numerical simulation employed an incompressible Navier-Stokes solver on a structured, embedded grid topology. New grid refinements were used to improve the accuracy of the solution near the overlapping grid boundaries. The effects of various tabs were studied at a constant Reynolds number on a two-element airfoil with a slotted flap. Both computed and measured results indicated that a tab in the main-element cove improved the maximum lift and lift-to-drag ratio relative to the baseline airfoil without a tab. Computed streamlines revealed that the additional turning caused by the tab may reduce the amount of separated flow on the flap. A three-element airfoil was also studied over a range of Reynolds numbers. For the optimized flap rigging, the computed and measured Reynolds number effects were similar. When the flap was moved from the optimum position, numerical results indicated that a tab may help to reoptimize the airfoil to within 1 percent of the optimum flap case.
    Keywords: AERODYNAMICS
    Type: NASA-CR-194592 , NAS 1.26:194592
    Format: application/pdf
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  • 7
    Publication Date: 2019-06-28
    Description: A 2-D numerical investigation was performed to determine the effect of a Gurney flap on a NACA 4412 airfoil. A Gurney flap is a flat plate on the order of 1 to 3 percent of the airfoil chord length, oriented perpendicular to the airfoil chord line and located at the trailing edge of the airfoil. An incompressible Navier Stokes code, INS2D, was used to calculate the flow field about the airfoil. The fully turbulent results were obtained using the Baldwin-Barth one-equation turbulence model. Gurney flap sizes of 0.5, 1, 1.25, 1.5, 2, and 3 percent of the airfoil chord were studied. Computational results were compared with experimental results where possible. The numerical solutions show that the Gurney flap increases airfoil lift coefficient with only a slight increase in drag coefficient. Use of a 1.5 percent chord Gurney flap increases the maximum lift coefficient by approximately 0.3 and decreases the angle of attack for a given lift coefficient by more than 3 degrees. The numerical solutions exhibit detailed flow structures at the trailing edge and provide a possible explanation for the increased aerodynamic performance.
    Keywords: AERODYNAMICS
    Type: NASA-CR-190576 , NAS 1.26:190576
    Format: text
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  • 8
    Publication Date: 2019-06-28
    Description: The injection of thin, high-momentum jets of air into the fuselage forebody boundary layers of the F-18 aircraft is explored numerically as a means of controlling the onset of fuselage vortices and of generating yaw control forces. The study was carried out for an angle of attack of 30 deg with symmetrical and asymmetrical blowing configurations. One-sided blowing results in a strongly asymmetrical flow pattern in the fore portion of the fuselage, leading to a net lateral force.
    Keywords: AERODYNAMICS
    Type: AIAA PAPER 90-0098
    Format: text
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  • 9
    Publication Date: 2019-06-28
    Description: In support of the NASA High Alpha Technology Program, Navier-Stokes solutions have been obtained using the Chimera overset grid scheme for flow over the wing, fuselage, and wing leading-edge extension (LEX) of the F/A-18 High Alpha Research Vehicle (HARV) at high incidence. Solutions are also presented for flow over the fuselage forebody at high angles of attack. The solutions are for turbulent flows at high-Reynolds-number flight-test conditions, and are compared with available qualitative and quantitative experimental data. Comparisons of predicted surface flow patterns, off-surface flow visualization, and surface-pressure distributions are in good agreement with flight-test data. The ability of the numerical method to predict the bursting of the LEX vortex as it encounters the adverse pressure gradient field of the wing is demonstrated, and the capability of predicting high-angle-of-attack aerodynamics around realistic aircraft configurations is established.
    Keywords: AERODYNAMICS
    Type: AIAA PAPER 90-0099
    Format: text
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  • 10
    Publication Date: 2019-06-28
    Description: This work is part of the high speed research program currently underway at NASA. This project has the goal of gaining understanding of the technical requirements for supersonic-hypersonic flight. Specifically, this research is part of a continuing project to study the laminar flow over swept wings at high speeds and involves the numerical prediction of the flow about the F-16XL wing. The research uses the CNS/ARC3D codes and the resulting crossflow velocity components in order to estimate transition locations on the wing. Effects of angle of attack on the extent of laminar flows was found to be minimal. This result can be attributed to the fact that a laminar flow airfoil was used in this study, which has a continuous favorable pressure gradient over approximately the first 20 percent of the chord for angles of attacks up to 10 degrees. It should also be noted that even after 20 percent chord the pressure gradient either slowly continued to increase, but never decreased before 90 percent chord, except for the higher swept cases when separation occurs. Angles of attack greater than 10 degrees were not considered since this study assumes natural laminar flow for normal supersonic cruise flight conditions.
    Keywords: AERODYNAMICS
    Type: NASA-CR-192706 , NAS 1.26:192706
    Format: application/pdf
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