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Our consultants regularly engage in research activities related to our normal client services. This archive includes the majority of the published technical papers, presentations, and other publications related to this research.

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Blong Xiong Colin Gordon Dale Pekrul Hal Amick Michael Gendreau Stephen Jaeger Steven Lank

Acoustics Construction Vibration Groundborne Vibration Infrasound Instrument Isolation Structural Vibration Vibration and Noise Criteria

Infrasound, Instrument Isolation, Acoustics

Control of infrasonic noise from mechanical ventilation systems in sensitive imaging laboratories

High resolution imaging equipment, such as transmission and scanning electron microscopes, can be very sensitive to the environment in which they are installed. Environmental factors including temperature, electromagnetic interference, vibration, and noise must be considered in the design of laboratories intended to house such instruments. With regard to noise, this equipment is often most sensitive […]...

Infrasound, Acoustics

Acoustics: The impact of low-frequency sound (infrasound) on imaging equipment in nanoscale research

The presentation reviews issues associated with low frequency sound—sources, human perception, typical levels, and effects on imaging systems. A set of infrasound criteria are presented which correlate imaging resolution with low frequency sound levels. Design features intended to mitigate infrasound generation and impact are discussed. M. Gendreau, "Acoustics: The impact of low-frequency sound (infrasound) on […]...

Acoustics

Solution of noise transmission problems by in situ segregation of composite transmission factors of complex partitions using sound intensity

In order to make the best decisions for reducing noise transmission through a complex partition, it is necessary to differentiate and determine the relative contribution of the partition elements to the transmitted noise. A “complex partition” is here defined as a partition with multiple elements in the plane perpendicular to the impinging noise, such as […]...

Infrasound, Acoustics

Measurement Techniques used to Verify the Cause and Nature of Low-frequency Noise in Rooms

Measurements in small rooms proposed for use as research laboratories indicated the presence of high amplitude infrasonic (i.e., at frequencies below 20 Hz) noise. Concern about this noise, which the author has further discovered to be common in many types of rooms, is due to the sensitivity to infrasound of the experiments proposed to be […]...

Infrasound, Instrument Isolation, Acoustics

The Effect of Varying Acoustic Pressure on Vibration Isolation Platforms Supported on Air Springs

Air spring isolation systems are commonly used to support sources of vibration, or equipment sensitive to vibration, in order to reduce vibration transmission from source to receiver. In the latter case, commercial isolation tables or custom-designed “plinths” may use isolation systems to provide reduced vibration environments at the base of sensitive equipment supported on them. […]...

Vibration and Noise Criteria, Infrasound, Acoustics

Generic Noise Criterion Curves for Sensitive Equipment

ABSTRACT Electron beam-based instruments, and other high-resolution instruments, are sensitive to the environment in which they operate. Adverse environments may limit achievable resolution. Equipment manufacturers provide specifications defining acceptable amplitudes of various environmental contaminants, such as vibration, electro-magnetic energies, and acoustic noise. However, the quality of these specifications varies significantly, from well-defined to conjectural. Additionally, […]...

Acoustics

Physics, Psychoacoustics, and Sound Spatialization

M. Gendreau, “Physics, Psychoacoustics, and Sound Spatialization,” Invited Presentation, Mills College, Oakland CA, USA, 14 November 2007....

Acoustics

Actual Vibration and Acoustics Measures on a Completed Nanotech Building — Duffield Hall

A case study, including vibration performance data, of one of the first buildings designed for nanoscale research. H. Amick, M. Gendreau and T. Xu, “Actual Vibration and Acoustics Measures on a Completed Nanotech Building — Duffield Hall,” invited presentation for the 2004 International Conference “Nanotechnology Research Space – The Next Step,” August 15-16, 2004, Ithaca, […]...

Acoustics

Specification of the effects of acoustic noise on optical tools

Optical Tools respond to internal vibration that can be excited by the external acoustic environment. The degree to which this occurs depends on many factors, but primarily the correspondence between the resonance characteristics of the tool and the frequency content of the acoustic environment in which it operates. Adverse noise environments, such as those often […]...

Acoustics

Aeroacoustic Study of Flap-tip Noise Reduction using Continuous Moldline Technology

B. L. Storms, J. A. Hayes, S. M. Jaeger, and P. T. Soderman, “Aeroacoustic Study of Flap-tip Noise Reduction using Continuous Moldline Technology,” AIAA 2000-1976, 6th AIAA/CEAS Aeroacoustics Conference, Lahaina, HI, June 12-14, 2000....

Acoustics

Effect of Surface Treatment on Array Microphone Self-noise

A method for reducing the flow-induced self-noise of acoustic array microphones was demonstrated in a wind tunnel. Unsteady boundary-layer flow in the wind tunnel induces large pressure fluctuations on exposed, flush-mounted microphone diaphragms, reducing the signal-to-noise capability of microphone arrays. Two important steps were take to reduce this background noise. First, the microphones were recessed […]...

Acoustics

Environmental Noise Control for Semiconductor Manufacturing Facilities

This paper summarizes the authors' experience in modeling and controlling environmental noise from more than 30 semiconductor manufacturing plants ("wafer fabs") within the past six years. This type of facility typically has a large number of concentrated noise sources because of the unusually large amount of intake and circulation air required to maintain cleanroom conditions, […]...

Acoustics

Effects of Acoustic Noise on Optical Equipment

Optical tools respond to internal vibration that can be excited by the external acoustic environment. The degree to which this occurs depends on many factors, but primarily the correspondence between the resonance characteristics of the tool and the frequency content of the acoustic environment in which it operates. Adverse noise environments, such as those often […]...

Acoustics

Noise and Vibration Characteristics of Cleanroom Fan-Filter Units

Fan-filter units are an increasingly popular alternative to packaged air handlers and fan-tower recirculation air systems. They are used in mini-environments and general cleanrooms, especially in retrofit cleanrooms with limited height. This paper presents noise and vibration data measured on 8 fan-filter units. It also presents measurement methods and performance criteria for fan-filter units. Colin […]...

Acoustics

The Problem of Duct-Generated Noise and its Prediction

In this paper we will present some of the more fundamental notions of the phenomena classified as “subsonic aerodynamic noise.” In light of these, we wish to discuss the mechanisms of noise generation responsible for the self-noise of sound-trap[s, dampers, diffusers and other duct-located flow discontinuities. Furthermore, we will suggest, on the basis of some […]...