1,803 research outputs found
The Topological Charges of the Affine Toda Solitons
The topological charges of the \an affine Toda solitons are considered. A
general formula is presented for the number of charges associated with each
soliton, as well as an expression for the charges themselves. For each soliton
the charges are found to lie in the corresponding fundamental representation,
though in general these representations are not filled. Each soliton's
topological charges are invariant under cyclic permutations of the simple roots
plus the extended root or equivalently, under the action of the Coxeter element
(with a particular ordering). Multisolitons are considered and are found to
have topological charges filling the remainder of the fundamental
representations as well as the entire weight lattice. The article concludes
with a discussion of some of the other affine Toda theories.Comment: 24 pages, LaTeX, DTP-93-3
An Exploratory Investigation of the Effects of a Thin Plastic Film Cover on the Profile Drag of an Aircraft Wing Panel
Exploratory wind tunnel tests were conducted on a large chord aircraft wing panel to evaluate the potential for drag reduction resulting from the application of a thin plastic film cover. The tests were conducted at a Mach number of 0.15 over a Reynolds number range from about 7 x 10 to the 6th power to 63 x 10 to the 6th power
Wind-tunnel results for an improved 21-percent-thick low-speed airfoil section
Low speed wind tunnel tests were conducted to evaluate the effects on performance of modifying a 23 percent thick low speed airfoil. The airfoil contour was altered to reduce the upper-surface adverse pressure gradient and hence reduce boundary layer separation. The chord Reynolds number varied from about 2,000,000 to 9,000,000
The Supervision-Evaluation Debate Meets the Theory-to-Practice Conundrum: Contemplations of a Practitioner Turned Professor
This article explores the tension between instructional supervision and teacher evaluation inherent in the professional literature and in practice. Moreover, it suggests engaging in formal appraisal processes less often to allow instructional leaders and classroom teachers more time for formative support for growth and improvement. Finally, this piece offers a range of formative development options and advocates teachers as educational professionals at a time when teacher quality and retention to the profession are paramount
Low-speed aerodynamic characteristics of a 13-percent-thick airfoil section designed for general aviation applications
Wind-tunnel tests were conducted to determine the low-speed section characteristics of a 13 percent-thick airfoil designed for general aviation applications. The results were compared with NACA 12 percent-thick sections and with the 17 percent-thick NASA airfoil. The tests were conducted ovar a Mach number range from 0.10 to 0.35. Chord Reynolds numbers varied from about 2,000,000 to 9,000,000
Wind tunnel testing of low-drag airfoils
Results are presented for the measured performance recently obtained on several airfoil concepts designed to achieve low drag by maintaining extensive regions of laminar flow without compromising high-lift performance. The wind tunnel results extend from subsonic to transonic speeds and include boundary-layer control through shaping and suction. The research was conducted in the NASA Langley 8-Ft Transonic Pressure Tunnel (TPT) and Low Turbulence Pressure Tunnel (LTPT) which have been developed for testing such low-drag airfoils. Emphasis is placed on identifying some of the major factors influencing the anticipated performance of low-drag airfoils
Low-speed wind-tunnel results for symmetrical NASA LS(1)-0013 airfoil
A wind-tunnel test has been conducted in the Langley Low-Turbulence Pressure Tunnel to evaluate the performance of a symmetrical NASA LS(1)-0013 airfoil which is a 13-percent-thick, low-speed airfoil. The airfoil contour was obtained from the thickness distribution of a 13-percent-thick, high-performance airfoil developed for general aviation airplanes. The tests were conducted at Mach numbers from 0.10 tp 0.37 over a Reynolds number range from about 0.6 to 12.0 X 10 to the 6th power. The angle of attack varied from about -8 to 20 degrees. The results indicate that the aerodynamic characteristics of the present airfoil are similar to, but slightly better than, those of the NACA 0012 airfoil
NASA low- and medium-speed airfoil development
The status of NASA low and medium speed airfoil research is discussed. Effects of airfoil thickness-chord ratios varying from 9 percent to 21 percent on the section characteristics for a design lift coefficient of 0.40 are presented for the initial low speed family of airfoils. Also, modifications to the 17-percent low-speed airfoil to reduce the pitching-moment coefficient and to the 21-percent low speed airfoil results are shown for two new medium speed airfoils with thickness ratios of 13 percent and 17 percent and design-lift coefficients of 0.30. Applications of NASA-developed airfoils to general aviation aircraft are summarized
Experimental Results for a Flapped Natural-laminar-flow Airfoil with High Lift/drag Ratio
Experimental results have been obtained for a flapped natural-laminar-flow airfoil, NLF(1)-0414F, in the Langley Low-Turbulence Pressure Tunnel. The tests were conducted over a Mach number range from 0.05 to 0.40 and a chord Reynolds number range from about 3.0 x 10(6) to 22.0 x 10(6). The airfoil was designed for 0.70 chord laminar flow on both surfaces at a lift coefficient of 0.40, a Reynolds number of 10.0 x 10(6), and a Mach number of 0.40. A 0.125 chord simple flap was incorporated in the design to increase the low-drag, lift-coefficient range. Results were also obtained for a 0.20 chord split-flap deflected 60 deg
Empowering Teachers Through Instructional Supervision: Using Solution Focused Strategies in a Leadership Preparation Program
The purpose of this study was to determine how students in an educational leadership preservice program perceived the effectiveness of solution-focused supervision (SFS) taught in an instructional supervision class. Interviews, observations, and artifacts, and a case study design, were applied to address two primary research questions. Findings revealed the use of solution-focused (SF) strategies produced positive outcomes, but required dramatic paradigm shifts from study participants. Moreover, the researchers found that respondents used a wide range of SF strategies in the clinical cycle exercise. Participants, furthermore, affirmed that SF structures and language promoted reflection, conversation, and empowerment of teachers. These positive dispositions toward solution-focused supervision, however, did not come without difficulties and initial doubt
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