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Full-Text Articles in Engineering

Or-05-6-4: Relating Human Productivity And Annoyance To Indoor Noise Criteria Systems: A Low Frequency Analysis, Erica Eileen Bowden, Lily M. Wang Jan 2005

Or-05-6-4: Relating Human Productivity And Annoyance To Indoor Noise Criteria Systems: A Low Frequency Analysis, Erica Eileen Bowden, Lily M. Wang

Durham School of Architectural Engineering and Construction: Faculty Publications

A number of indoor noise criteria systems are used to quantify the background noise in a built environment, including Noise Criteria (NC), Balanced Noise Criteria (NCB), Room Criteria (RC), Room Criteria Mark II (RC Mark II), A-weighted Equivalent Sound Pressure Level (LAeq), and others. An on-going debate exists in the acoustical community over which criterion is the most appropriate to use in the variety of ambient noise situations encountered. In an effort to quantitatively support the use of individual criterion, this project subjectively correlates these various criteria with human task performance and perception. Eleven subjects participated in a …


Using Multi-Stack And Variable-Speed-Drive Systems To Reduce Laboratory Exhaust Fan Energy, Gang Wang, Mingsheng Liu Jan 2005

Using Multi-Stack And Variable-Speed-Drive Systems To Reduce Laboratory Exhaust Fan Energy, Gang Wang, Mingsheng Liu

Durham School of Architectural Engineering and Construction: Faculty Publications

In buildings that contain laboratories, fume hoods are normally used to control contaminant concentrations. Exhaust stacks with a constant exit velocity are required to make sure that dangerous concentrations do not occur in occupied areas near the building or on the roof top. To achieve constant velocity when exhaust flow rates are less than design, makeup air is introduced to the system at the inlet of the exhaust fan. Since laboratory exhaust airflow is often significantly less than the design airflow, exhaust fans consume significantly more energy than is necessary. To reduce exhaust fan energy, techniques involving multiple exhaust stacks …


Mechanical Damping System For Structures, Jay A. Puckett, Patrick S. Mcmanus, Homer R. Hamilton Iii Jan 2005

Mechanical Damping System For Structures, Jay A. Puckett, Patrick S. Mcmanus, Homer R. Hamilton Iii

Durham School of Architectural Engineering and Construction: Faculty Publications

A mechanical damping system for a structure is provided. The mechanical damping system comprises a tubular impact frame secured to the structure. A support frame is secured to the structure with the support frame spaced from the impact frame. An elongated member is provided having a first end and a second end. The first end is secured within the support frame and the second end is free from connection and extends into the impact frame. At least one impact mass is secured to the second end of the elongated member, the impact mass movable within and contactable with the impact …