General Electric Company

Frederic Ghislain Pla

Imdad Imam

Stephen Linwood Smith

Frank Albert Pitman, Jr

Robert Arvin Hedeen

Harindra Rajiyah

William A Edelstein

Ravi Rajamani

Michael J Radziun

Scott Thomas Mansell

Thomas Gerard Ebben

Peter Ping-Liang Sue

Kemakolam Michael Obasih

Robert James Dobberstein

A magnetic-resonance-imaging (MRI) scanner subassembly. In one subassembly, a preferably annularly-cylindrical-shaped enclosure contains a first vacuum, and an MRI gradient coil assembly is located within the enclosure in the first vacuum. Preferably, an annularly-cylindrical housing is included which is coaxially aligned with the enclosure and contains a second vacuum which is higher than the first vacuum, and an MRI superconductive main coil is located within the housing in the second vacuum. In another subassembly, an MRI gradient coil assembly has a threshold excitation frequency, and an isolation mount assemblage supports the MRI gradient coil assembly.

Low noise MRI scanner

A method for reducing the total operating noise and/or the total vibration of at least two generally-identical rotating machines. In one embodiment, the noise (or vibration) contribution of each machine at a predetermined reference relative phase angle is estimated. Optimum phase angles are calculated by minimizing a cost function which includes such estimated noise (or vibration) contributions and each rotating machine's relative phase angle. In another embodiment, the gradient of a weighted sum of a measure of the magnitude of the acoustic pressure amplitude of the total operating noise (or the amplitude of the total vibration) is measured. Each machine phase angle is adjusted by a predetermined increment opposite in sign to its associated gradient. The measuring and adjusting are repeated until the gradient is within a limit.

Method for reducing noise and/or vibration from multiple rotating

An electrical transformer includes a tank containing transformer fluid and a transformer core and winding subassembly located in the transformer fluid within the tank. The electrical transformer also includes a mechanism for varying the dynamic pressure of the transformer fluid within the tank during electromagnetic operation of the transformer core and winding subassembly to cancel out (or reduce) noise-causing vibrations in the transformer fluid which come from the operating transformer core and winding subassembly. Preferably, the electrical transformer further includes an active mount subassembly.

Electrical transformer with reduced core noise

An electrical transformer includes a housing, a transformer core and winding subassembly located within the housing, and an active mount subassembly having an active mount and a controller. The active mount has a first end attached to the housing and a second end attached to the transformer core and winding subassembly. The controller has an output port connected to the active mount. The active mount cancels out (or reduces) noise-causing vibrations which come from the transformer core and winding subassembly during transformer operation.

An electrical transformer includes a housing, a transformer core and winding subassembly located in the housing, and a cooling fan subassembly. The cooling fan subassembly includes a variable speed fan located outside the housing, a temperature sensor located near the housing, and a controller having an output port connected to the variable speed fan and an input port connected to the temperature sensor. The controller reduces the fan speed (and hence the fan noise) when a lower fan speed can maintain the desired temperature as sensed by the temperature sensor. Preferably, the electrical transformer further includes an active mount subassembly and/or (when the housing includes a tank containing transformer fluid) a mechanism for varying the dynamic pressure of such transformer fluid.

Electrical transformer with reduced fan noise

A perimeter monitoring device is disposed so as to detect passage of objects through a monitored space above a perimeter line and to generate a perimeter signal in correspondence with such a detected passage. The monitoring device includes at least one sensor element disposed along the perimeter line to be monitored and a processing unit coupled to the sensor element so as to detect electrical current generated in the sensor element from the movement of the intruding object past the sensor element. Each sensor element comprises a loop of electrically conductive material that is electrically isolated from the other sensor element, and each of which is separately electrically coupled to the processing unit. The perimeter detection system further comprises an electrical insulation material, such as a mat, that is disposed between the conductive sensor element and the monitored space. The signal generated by the processing unit in correspondence with the detection of an object passing through the monitored area is typically coupled to control mechanisms for the equipment, such as a radiation imager, located within the cordoned area, so that operation of the equipment can be stopped or modified to minimize the chance of the equipment causing harm to an intruder passing across the perimeter line.

Perimeter sensing device

An active noise control subassembly array for reducing noise caused by a source (such as an aircraft engine). A pair of subassemblies each has a piezoceramic-driven noise radiating panel to generate a panel noise canceling at least some of the source noise. A front plate is spaced apart from the panel and has a sound exit port. A first pair of spaced-apart side walls each generally abuts the panel and the front plate so as to generally enclose a front cavity to define a resonator. A back plate is spaced apart from the panel by a second pair of side walls. The pair of subassemblies are spaced apart to create a space between their adjacent side walls. A third subassembly is similar to the pair of subassemblies but may have a different resonant frequency and is positioned such that the back plates of the subassembly pair serve as the front plate of the third subassembly with the space between the subassembly pair serving as the sound exit port of the third subassembly.

Active noise control using an array of plate radiators and acoustic

An active noise control subassembly for reducing noise caused by a source (such as an aircraft engine) independent of the subassembly. A noise radiating panel is bendably vibratable to generate a panel noise canceling at least a portion of the source noise. A piezoceramic actuator plate is connected to the panel. A front plate is spaced apart from the panel and the first plate, is positioned generally between the source noise and the panel, and has a sound exit port. A first pair of spaced-apart side walls each generally abut the panel and the front plate so as to generally enclose a front cavity to define a resonator.

Noise control using a plate radiator and an acoustic resonator

An active noise control subassembly for an aircraft engine. An aircraft engine noise radiating panel is bendably vibratable to generate a canceling noise generally opposite in phase to at least a portion of the discrete tonal noise produced by the engine. A piezoceramic actuator plate is vibratable by an applied electric AC signal. The plate is connected to the panel such that vibrations in the plate cause bending vibrations in the panel and such that the plate is compressively prestressed along the panel when the panel is free of bending vibrations. The compressive prestressing increases the amplitude of the canceling noise before the critical tensile stress level of the plate is reached. Preferably, a positive electric DC bias is also applied to the plate in its poling direction to increase the amplitude of the canceling noise before the sum of the AC signal and DC bias exceeds the depolarization voltage in a direction opposite to the poling direction.

Active noise control of aircraft engine discrete tonal noise

An active vibration control subassembly for a structure (such as a jet engine duct or a washing machine panel) undergoing bending vibrations caused by a source (such as the clothes agitator of the washing machine) independent of the subassembly. A piezoceramic actuator plate is vibratable by an applied electric AC signal. The plate is connected to the structure such that vibrations in the plate induced by the AC signal cause canceling bending vibrations in the structure and such that the plate is compressively pre-stressed along the structure when the structure is free of any bending vibrations. The compressive prestressing increases the amplitude of the canceling bending vibrations before the critical tensile stress level of the plate is reached. Preferably, a positive electric DC bias is also applied to the plate in its poling direction.

Active vibration control of structures undergoing bending vibrations

A signal enhancement system for separating a composite diagnostic signal detected in a rotating machine into component signals representative of the contributions to the composite signal of a number of independent sources. The signal enhancement system includes at least one signal subtraction loop having a transducer which produces a reference signal based on the rotational speed of a rotating shaft in the machine and an adaptive filter connected to the transducer. The adaptive filter processes the reference signal to produce a component signal which closely approximates the contribution of the rotating shaft to the composite signal. A summer is also included which subtracts the component signal from the composite diagnostic signal to produce a second component signal. Both the first and second component signals are provided as outputs of the system. The system can be implemented with a plurality of signal subtraction loops wherein, the summer of the first loop subtracts the component signal of the first loop's adaptive filter from the composite diagnostic signal to produce an output signal. Then, the summer of each successive loop subtracts the component signal of that loop's adaptive filter from the output signal of the prior loop. The last output signal and each component signal are the system output.

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Clifton Park, NY, United States of America

Frederic Ghislain Pla