General Electric

About: General Electric is a company organization based out in Boston, Massachusetts, United States. It is known for research contribution in the topics: Turbine & Rotor (electric). The organization has 76365 authors who have published 110557 publications receiving 1885108 citations. The organization is also known as: General Electric Company & GE.

Magnetic-Field Dependence of the Ultrasonic Attentuation in Metals

Abstract: A self-consistent, semiclassical treatment is given for the attenuation of a sound wave by a free-electron gas in a positive background which supports the sound wave. Emphasis is placed upon the kinds of magnetic-field dependence which can be found under a wide range of values for the magnetic field, frequency, and mean free path. Applications of the general formalism include propagation parallel and perpendicular to the magnetic field. The special phenomena studied include geometric resonances, cyclotron resonances, and magneto-plasma resonance. A qualitative physical interpretation of the various effects found in the detailed calculations is also presented.

Dynamic scan plane tracking using MR position monitoring

Abstract: An MRI system measures the movements of a subject during the acquisition of a series of NMR images and automatically updates the scan parameters such that the image plane or volume tracks the movement of the anatomy of interest. An array of tracking coils fasten to the subject and an NMR measurement pulse sequence is interleaved with the image acquisitions to measure the location of the tracking cols.

Methods and apparatus for model based diagnostics

Abstract: Systems and methods for performing module-based diagnostics are described. In an exemplary embodiment, sensor values from an actual engine plant are input to an engine component quality estimator which generates performance estimates of major rotating components. Estimated performance differences are generating by comparing the generated performance estimates to a nominal quality engine. The estimated performance differences, which are indicative of component quality, are continuously updated and input to a real-time model of the engine. The model receives operating conditional data and the quality estimates are used to adjust the nominal values in the model to more closely match the model values to the actual plant. Outputs from the engine model are virtual parameters, such as stall margins, specific fuel consumption, and fan/compressor/turbine efficiencies. The virtual parameters are combined with the sensor values from the actual engine plant in a fault detection and isolation classifier to identify abnormal conditions and/or specific fault classes, and output a diagnosis.

Equivalent Circuits for Discontinuities in Transmission Lines

Abstract: Exact equivalent circuits for several types of discontinuities in parallel-plane transmission lines are obtained by Hahn's method of matching electromagnetic-wave solutions. Values of lumped elements to be used in these are given in curve form, with rules for using results in the corresponding coaxial-line problems. Experimental checks are reported, which verify results of the calculations and stress the importance of the discontinuity capacitances appearing in the equivalent circuits.

High-voltage normally off GaN MOSFETs on sapphire substrates

Abstract: Gallium nitride self-aligned MOSFETs were fabricated using low-pressure chemical vapor-deposited silicon dioxide as the gate dielectric and polysilicon as the gate material. Silicon was implanted into an unintentionally doped GaN layer using the polysilicon gate to define the source and drain regions, with implant activation at 1100/spl deg/C for 5 min in nitrogen. The GaN MOSFETs have a low gate leakage current of less than 50 pA for circular devices with W/L=800/128 /spl mu/m. Devices are normally off with a threshold voltage of +2.7 V and a field-effect mobility of 45 cm/sup 2//Vs at room temperature. The minimum on-resistance measured is 1.9 m/spl Omega//spl middot/cm/sup 2/ with a gate voltage of 34 V (W/L=800/2 /spl mu/m). High-voltage lateral devices had a breakdown voltage of 700 V with gate-drain spacing of 9 /spl mu/m (80 V//spl mu/m), showing the feasibility of self-aligned GaN MOSFETs for high-voltage integrated circuits.