Wright-Patterson Air Force Base

About: Wright-Patterson Air Force Base is a other organization based out in Wright-Patterson AFB, Ohio, United States. It is known for research contribution in the topics: Laser & Microstructure. The organization has 5817 authors who have published 9157 publications receiving 292559 citations. The organization is also known as: Wright-Patterson AFB & FFO.

Unsteady force generation and vortex dynamics of pitching and plunging aerofoils

Abstract: Experimental studies of the flow topology, leading-edge vortex dynamics and unsteady force produced by pitching and plunging flat-plate aerofoils in forward flight at Reynolds numbers in the range 5000–20 000 are described. We consider the effects of varying frequency and plunge amplitude for the same effective angle-of-attack time history. The effective angle-of-attack history is a sinusoidal oscillation in the range to with mean of and amplitude of . The reduced frequency is varied in the range 0.314–1.0 and the Strouhal number range is 0.10–0.48. Results show that for constant effective angle of attack, the flow evolution is independent of Strouhal number, and as the reduced frequency is increased the leading-edge vortex (LEV) separates later in phase during the downstroke. The LEV trajectory, circulation and area are reported. It is shown that the effective angle of attack and reduced frequency determine the flow evolution, and the Strouhal number is the main parameter determining the aerodynamic force acting on the aerofoil. At low Strouhal numbers, the lift coefficient is proportional to the effective angle of attack, indicating the validity of the quasi-steady approximation. Large values of force coefficients () are measured at high Strouhal number. The measurement results are compared with linear potential flow theory and found to be in reasonable agreement. During the downstroke, when the LEV is present, better agreement is found when the wake effect is ignored for both the lift and drag coefficients.

Effects of Job Enrichment and Task Goals on Satisfaction and Productivity: Implications for Job Design

Abstract: : A two phase research project investigated the effects of job enrichment and goal setting on worker productivity and satisfaction in a well-controlled, simulated job environment. In the first phase, two conditions of goal setting (assigned goals versus no goals) and two conditions of job enrichment (enriched versus unenriched) were established, producing four experimental conditions. In the second phase (after 2 days work) people with unenriched jobs worked under the enrichment conditions and people originally without goals were assigned goals. Results are discussed in terms of the current theoretical approaches for understanding employee motivation on the job.

Polarization-controlled, photodriven bending in monodomain liquid crystal elastomer cantilevers

Abstract: We report on the fast and optically controlled angular bending of cantilevers made from liquid crystal polymer networks functionalized with azobenzene moieties (azo-LCN). For potential applications such as adaptive optics, photoresponsive cantilevers should rapidly deform to controlled angles while maintaining a modulus that can accomplish appreciable mechanical work. This work demonstrates cantilevers made of monodomain azo-LCN containing pendant (side chain) azobenzene mesogens with a storage modulus of 1.4 GPa bend 85° in less than 300 ms upon exposure to 442 nm irradiation. Moreover, the bending angle of these monodomain azo-LCN cantilevers can be controlled by the polarization angle of the source relative to the long-axis of the cantilever. The bending performance (deformation angle and speed) of this monodomain system is compared to a polydomain analogue. The impact of azobenzene concentration, laser intensity, and thickness on these parameters is also presented.

Comparison of high-voltage ac and pulsed operation of a surface dielectric barrier discharge

Abstract: A surface dielectric barrier discharge (DBD) in atmospheric pressure air was excited either by low frequency (0.3–2 kHz) high-voltage ac or by short, high-voltage pulses at repetition rates from 50 to 600 pulses s−1. The short-pulse excited discharge was more diffuse and did not have the pronounced bright multiple cathode spots observed in the ac excited discharge. The discharge voltage, current and average power deposited into the discharge were calculated for both types of excitation. As a measure of plasma-chemical efficiency, the ozone number density was measured by UV absorption as a function of average deposited power. The density of ozone produced by ac excitation did not increase so rapidly as that produced by short-pulse excitation as a function of average power, with a maximum measured density of ~3 × 1015 cm−3 at 25 W. The maximum ozone production achieved by short-pulse excitation was ~8.5 × 1015 cm−3 at 20 W, which was four times greater than that achieved by ac excitation at the same power level.