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There are two kinds of emission testing that Expert has done: sound pressure and sound power. Using sound pressure, Expert has determined local dB and/or dBA levels as well as measures of psychoacoustic metrics, such as Zwicker loudness, sharpness, intelligibility, roughness, etc. By means of sound intensity and sound power measurement, Expert has obtained localization of sound emission from a structure, as well as the calculation of the total sound power (in watts) radiated by a structure. Making a sound power measurement according to ISO 532B, Expert demonstrated that a new product from his company had only 1/2 the sound power emission of a competitor's, and this information was duly exploited by the marketing people.

Expert has performed experiments to determine the minimum number of degrees of freedom required in finite elements of centrifuge substructures, and he often used modal degrees of freedom for frequency response analysis when the number of physical degrees of freedom became excessively large (typically near 1 million dof).

In his studies of centrifuge dynamics, Expert utilized both computational techniques (such as finite element analysis) and experimental
techniques (such as frequency response function measurement and spectral decomposition of a time signal). His analyses of the dynamics of
centrifuges has allowed Beckman Coulter Corporation to remain the world leader in ultracentrifuge development and marketing while Expert
worked there.

Expert has worked both alone and with other consultants to precisely compare the acoustical performance of his company's products with those of the competition and to help show the way to improvement. His work during 2005-2007 resulted in the design of an ultracentrifuge whose noise output was only 5% that of its predecessor instrument.

Expert has used finite element (Nastran) models to calculate the normal and complex modes of centrifuges, to predict the instability of precessional modes of a rotating structure, to predict the response of a rotating system to rotor imbalance, and to predict the transient response of a system to a transient excitation. Examples of his experimental work include the use of measured frequency response functions to validate finite element models, the use of accelerometers and displacement probes to measure the time-dependence of motions on the structure, and the use of impact hammers and shakers to excite structures in controlled ways.


For more than 15 years, Expert played the lead role at Beckman Coulter Corporation in both computational and experimental dynamics for centrifuge development, and he mentored the younger engineers there in the application of those techniques.

Expert measured vibrations using accelerometers, eddy-current proximity probes, and capacitative probes. Some of these measurements were of vibrations during operation of centrifuges, while others were responses to measured force excitations (from an impact hammer or an electromagnetic shaker). Both the accelerometers and the force transducers were of the piezoelectric variety, with some of them requiring charge amplifiers and others (ICP) being stand-alone. The vibration data were used to confirm finite element model accuracy (via frequency response functions), design improvements, and sources of acoustical noise. The data were used to improve product performance and to help manufacturing improve their yields.

Expert always used calibration shakers to insure that the sensitivity of his accelerometers was known to within better than 1% accuracy. He calibrated eddy-current proximity probes and capacitative probes by means of micrometer-driven displacement stages (e.g., from Newport Corporation). He calibrated force cells indirectly using a ballistic pendulum of known mass. He was responsible for the annual calibration of all the sound and vibration instrumentation at Beckman Coulter's Palo Alto site via the use of a professional facility (Odin Metrology, Inc.) using procedures and equipment traceable to NIST standards.

Expert used vibration testing, over a period of more than 15 years, for the following purposes:


1) Diagnosis of sub-sychronous whirl in centrifuge drives, using spectral analysis.


2) High amplitude vibration of panels leading to undesirable acoustic radiation.


3) Generation of frequency response functions for determining the frequencies of resonances.


4) Determination of non-linear vibrations via spectral analysis of raw data.


5) Comparison of design iterations with respect to their vibration performance.


Using Nastran code and modal testing, he played the key dynamics analysis role in the design of a new family of general purpose centrifuges. As Beckman Coulter's in-house consultant in the field of structural dynamics, he helped to make the Allegra-15 centrifuge the quietest general purpose centrifuge created by Beckman Coulter since 1985.Using Nastran, diagnosed and prescribed successful treatment for a vibration problem that led to a one month stop-ship condition following the adoption of a cost-control design change. Resolution of the problem resulted in resumption of shipping in less than 3 weeks.Using impact hammer testing, diagnosed a cooling fin resonance that was generating unacceptable noise in a new ultracentrifuge model. Worked with design engineer to modify fin design, resulting in satisfactory acoustical performance.Using non-synchronous perturbation testing, diagnosed a sub-synchronous unstable precessional mode that was creating problems in manufacturing of a general purpose centrifuge. The problem was eventually found to be due to loss of damping in an elastomeric mount owing to elevated temperature. Change of the elastomer solved the instability problem.Using patented techniques for centrifuge motor speed control, found an absolutely optimized speed protocol for the separation of nicked from circular DNA plasmids from bacteria.