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DE Cox

Publications and source records attributed to DE Cox.

At least 19 recordsLinked to original sources
PubMed2000

Origin of the high piezoelectric response in PbZr1-xTixO3

High resolution x-ray powder diffraction measurements on poled PbZr1-xTixO3 (PZT) ceramic samples close to the rhombohedral-tetragonal phase boundary (the so-called morphotropic phase boundary) have shown that for both rhombohedral and tetragonal compositions the piezoelectric elongation of the unit cell does not occur along the polar directions but along those directions associated with the monoclinic distortion. This work provides the first direct evidence for the origin of the very high piezoelectricity in PZT.

Journal Article↗
PubMed2000

Active control design for acoustic radiation using mixed-norm optimization

Linear matrix inequalities were applied to design a mixed H2/H(infinity) feedback control compensator for a structural acoustic system. The compensator was designed to minimize the H2 norm of radiation filters while constraining the H(infinity) norm through the control path to be less than unity. A trade-off between minimizing sound power radiated and maximum rms gain in the control path resulted in a reliable and robust means of designing compensators for structural acoustic control.

Journal Article↗
PubMed2000

Radiation modal expansion: application to active structural acoustic control

This paper demonstrates active structural acoustic control using multiple input/output adaptive sensoriactuators combined with radiation filters and a feedback control paradigm. A new method of reduced order modeling/design of radiation filters termed radiation modal expansion (RME) is presented. For the experiments detailed in this paper, the RME technique reduced the modeling of the radiation matrix from 400 transfer functions to 6 transfer functions (multiplied by a constant transformation matrix). Experimental results demonstrate reductions of radiated sound power on the order of 5 dB over the bandwidth of 0-800 Hz.

Journal Article↗