Optimization of suppression for two-element treatment liners for turbomachinery exhaust ducts

Sound wave propagation in a soft-walled rectangular duct with steady uniform flow was investigated at exhaust conditions, incorporating the solution equations for sound wave propagation in a rectangular duct with multiple longitudinal wall treatment segments. Modal analysis was employed to find the solution equations and to study the effectiveness of a uniform and of a two-sectional liner in attenuating sound power in a treated rectangular duct without flow (M = 0) and with uniform flow of Mach 0.3. Two-segment liners were shown to increase the attenuation of sound as compared to a uniform liner. The predicted sound attenuation was compared with measured laboratory results for an optimized two-segment suppressor. Good correlation was obtained between the measured and predicted suppressions when practical variations in the modal content and impedance were taken into account. Two parametric studies were also completed

Effects of competitive reward distribution on auditing and competitive responding.

This study allowed subjects to audit each other's responding during a series of competitive contests. Six pairs of female college students competed in 3-min contests in which the competitive response was a knob pull. A sum of money was divided using a proportional distribution or a 100%/0% reward distribution. In the proportional distribution, a subject's proportion of the sum was her proportion of the total number of responses. Also, in every contest either subject could make a response that would end the contest prematurely and give both subjects the same amount: a sum equal to 33% of the competitive total. Each subject could press either or both of two audit buttons that displayed her own and the other's response total for 10 s. Results replicated earlier findings in showing the superiority of the proportional distribution in total number of competitive responses made. No subject audited continuously, and only 1 audited most of the time. Most audits were interpersonal, including both own and other's scores. Auditing typically was more frequent in 100%/0% contests in which subjects were more likely to stop the contest when they were far behind. Winners were more likely to audit than were losers. Competitive response rates increased when the differences revealed by audits were small and decreased when they were large. Overall audit patterns were consistent with the view that feedback as "news" is more often sought when it can lead to improved outcomes