The stabilization of thiepin by substitution

Resonance energies of 430 substituted thiepins have been calculated using a simple Hückel method described before. The results predict that thiepins substituted with electron-withdrawing groups (methoxycarbonyl and fluorine) will be less antiaromatic than the parent thiepin. Thus the calculated REPE of the only known type of monocyclic thiepin viz. 3,4 - bis(methoxycarbonyl) - 5 pyrrolidinothiepin (-0.007β) is less negative than that of the parent thiepin

Improved solution for potential flow about arbitrary axisymmetric bodies by the use of a higher-order surface source method. Part 1. Theory and results

The surface-source method of calculating potential flow is improved by refining the underlying numerical analysis. The analysis uses parabolic elements and linearly-varying source density. The result is a large increase in computing speed and accuracy. The theory is described, and the effectiveness of the modification is illustrated

Meditation and awakening: An exploration of the wind music of Eric Guinivan

American composer and percussionist Eric Guinivan is a rising star in the world of composition. He is the recipient of several major awards including the Morton Gould Young Composer Award, the BMI Student Composer’s Award, and was nominated for a Grammy Award for Best Small Ensemble Performance for his work with the Los Angeles Percussion Quartet. His work Meditation and Awakening was hailed by the New York Times as “engaging,” and commented on the work’s “shimmering colors” and “frenetic energy.” His pieces for wind band have been performed around the country, including at national and regional conferences of the College Band Directors National Association (CBDNA). The purpose of this document is to explore and elucidate the current compositions for wind band by the composer. Three works will be studied in depth: Fractured Light (2012), Vicious Cycle (2014), and Meditation and Awakening (originally composed in 2010 but transcribed for wind band in 2016 by the author). Biographical information, theoretical analyses, performance considerations, and information regarding the transcription process will be discussed

Steady and unsteady transonic pressure measurements on a clipped delta wing for pitching and control-surface oscillations

Steady and unsteady pressures were measured on a clipped delta wing with a 6-percent circular-arc airfoil section and a leading-edge sweep angle of 50.40 deg. The model was oscillated in pitch and had an oscillating trailing-edge control surface. Measurements were concentrated over a Mach number range from 0.88 to 0.94; less extensive measurements were made at Mach numbers of 0.40, 0.96, and 1.12. The Reynolds number based on mean chord was approximately 10 x 10 to the 6th power. The interaction of wing or control-surface deflection with the formation of shock waves and with a leading-edge vortex generated complex pressure distributions that were sensitive to frequency and to small changes in Mach number at transonic speeds

A vapor generator for transonic flow visualization

A vapor generator was developed for use in the NASA Langley Transonic Dynamics Tunnel (TDT). Propylene glycol was used as the vapor material. The vapor generator system was evaluated in a laboratory setting and then used in the TDT as part of a laser light sheet flow visualization system. The vapor generator provided satisfactory seeding of the air flow with visible condensate particles, smoke, for tests ranging from low subsonic through transonic speeds for tunnel total pressures from atmospheric pressure down to less than 0.1 atmospheric pressure