Acoustics, Dynamics, and Controls Commons^™

Electro-Osmotic Flow Over A Charged Superhydrophobic Surface, Hui Zhao

Mechanical Engineering Faculty Research

Bubbles can be trapped inside textured structures such as grooves, forming a superhydrophobic surface. A superhydrophobic surface has a large effective hydrodynamic slip length compared to a smooth hydrophobic surface and holds the promise of enhancing electrokinetic flows that find many interesting applications in microfluidics. However, recent theoretical studies suggested that electro-osmotic flows over a weakly charged superhydrophobic surface

the zeta potential of the surface is smaller than the thermal potential (25 mV) can only be enhanced when liquid-gas interfaces are charged [T. M. Squires, Phys. Fluids 20, 092105 (2008); Bahga et al., J. Fluid Mech. 644, 245 (2010)]. So …

Ab-10-017: Combined Effects Of Noise And Temperature On Human Comfort And Performance (1128-Rp), Dale Tiller, Lily M. Wang, Amy Musser, Matthew Radik

Durham School of Architectural Engineering and Construction: Faculty Publications

This paper summarizes results from an experiment designed to investigate the combined effects of noise and temperature on human thermal comfort and task performance. Thirty subjects (16 females, 14 males) were exposed to all combinations of five thermal conditions (PMV +1 [79.6°F:26.4°C], PMV +0.5 [75.8°F:24.3°C], PMV 0 [72.1°F:22.3°C], PMV -0.5 [68.3°F:20.2°C], and PMV -1 [64.6°F:18.1°C]), three RC noise levels (RC-30, RC-40, and RC-50), and two sound qualities (neutral and rumbly): all sounds mimicked noise from building ventilation systems. After a one-hour adaptation period at each condition, subjects rated their thermal comfort using the ASHRAE Thermal Comfort Scale and the Tenant …

Ab-10-019: Human Performance And Perception-Based Evaluations Of Indoor Noise Criteria For Rating Mechanical System Noise With Time-Varying Fluctuations (1322-Rp), Lily M. Wang, Cathleen C. Novak

Durham School of Architectural Engineering and Construction: Faculty Publications

The goal of this study was to investigate the effects of noise from building mechanical systems with time-varying fluctuations on human task performance and perception, and to determine how well current indoor noise rating methods account for this performance and perception. Six different noise conditions with varying degrees of time-varying fluctuations, many focused in the low frequency rumble region, were reproduced in an office-like setting. Thirty participants were asked to complete typing, grammatical reasoning, and math tasks plus subjective questionnaires, while being exposed for approximately one hour to each noise condition. Results show that the noise conditions with higher sound …