Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.