Showing papers by "General Electric published in 1996"

The role of magnetic susceptibility in magnetic resonance imaging: MRI magnetic compatibility of the first and second kinds

Abstract: The concept of magnetic susceptibility is central to many current research and development activities in magnetic resonance imaging (MRI); for example, the development of MR-guided surgery has created a need for surgical instruments and other devices with susceptibility tailored to the MR environment; susceptibility effects can lead to position errors of up to several millimeters in MR-guided stereotactic surgery; and the variation of magnetic susceptibility on a microscopic scale within tissues contributes to MR contrast and is the basis of functional MRI. The magnetic aspects of MR compatibility are discussed in terms of two levels of acceptability: Materials with the first kind of magnetic field compatibility are such that magnetic forces and torques do not interfere significantly when the materials are used within the magnetic field of the scanner; materials with the second kind of magnetic field compatibility meet the more demanding requirement that they produce only negligible artifacts within the MR image and their effect on the positional accuracy of features within the image is negligible or can readily be corrected. Several materials exhibiting magnetic field compatibility of the second kind have been studied and a group of materials that produce essentially no image distortion, even when located directly within the imaging field of view, is identified. Because of demagnetizing effects, the shape and orientation, as well as the susceptibility, of objects within and adjacent to the imaging region is important in MRI. The quantitative use of susceptibility data is important to MRI, but the use of literature values for the susceptibility of materials is often difficult because of inconsistent traditions in the definitions and units used for magnetic parameters-particularly susceptibility. The uniform use of SI units for magnetic susceptibility and related quantities would help to achieve consistency and avoid confusion in MRI.

Complete PCB congener distributions for 17 Aroclor mixtures determined by 3 HRGC systems optimized for comprehensive, quantitative, congener-specific analysis

Abstract: Three HRGC systems (1: 30m DB-XLB capillary with MS-SIM detection; 2: 60m DB-XLB capillary with full-scan, ion-trap MS detection; and 3: Parallel dual-column DB-17 and series-coupled HP5/HT5 with ECD detection) were used to completely characterize multiple lots of 8 different-numbered Aroclor mixtures by quantitative calibration against 9 solutions containing primary standards of all 209 PCB congeners. Despite lower absolute sensitivity and more Aroclor congener coelutions than the dual-column ECD system, the MS systems enabled measurement of more congeners per Aroclor since their greater linear response range did not require dilution of samples and standards. Pairs of different lots of Aroclors 1248 and 1254 displayed markedly different proportions of congeners, and the 1254 pair displayed strong differences in the extent of ortho-chlorine substitution. The tables of congener weight percent distributions among Aroclors are more comprehensive and quantitatively precise than those of prior publications. However, the limitations of single-level calibration precluded measurement of all congeners to the ±10% accuracy desirable for establishing these Aroclors as secondary standards for comprehensive, quantitative congener-specific PCB analysis.

Dual fuel mixer for gas turbine combustor

Abstract: An air fuel mixer is disclosed having a mixing duct, a shroud surrounding the upstream end of the mixing duct in which a fuel manifold is provided in flow communication with a fuel supply and control means, a set of inner and outer counter-rotating swirlers adjacent the upstream end of the mixing duct for imparting swirl to an air stream, a hub separating the inner and outer annular swirlers to allow independent rotation of the air stream, and a centerbody located axially along and substantially the full length of the mixing duct. In order to inject one type of fuel into the mixing duct, fuel is supplied to the outer annular swirlers which include hollow vanes with internal cavities, wherein the internal cavities of the outer swirler vanes are in fluid communication with the fuel manifold in the shroud. The outer swirler vanes further include a plurality of fuel passages therethrough in flow communication with the internal cavities. A second fuel can be injected into the mixing duct by means of a plurality of orifices in the centerbody wall which are in flow communication with a fuel supply and control means. In this way, high pressure air from a compressor is injected into the mixing duct through the swirlers to form an intense shear region and fuel is injected into the mixing duct from the outer swirler vane passages and/or the centerbody orifices so that the high pressure air and the fuel is uniformly mixed therein so as to produce minimal formation of pollutants when a fuel/air mixture is exhausted out the downstream end of the mixing duct into the combustor and ignited.

The balance of mechanical and environmental properties of a multielement niobium-niobium silicide-based in situ composite

Abstract: This article describes room-temperature and high-temperature mechanical properties, as well as oxidation behavior, of a niobium-niobium silicide basedin situ composite directionally solidified from a Nb-Ti-Hf-Cr-Al-Si alloy. Room-temperature fracture toughness, high-temperature tensile strength (up to 1200 °C), and tensile creep rupture (1100 °C) data are described. The composite shows an excellent balance of high- and low-temperature mechanical properties with promising environmental resistance at temperatures above 1000 °C. The composite microstructures and phase chemistries are also described. Samples were prepared using directional solidification in order to generate an aligned composite of a Nb-based solid solution with Nb3Si- and Nb5Si3-type silicides. The high-temperature mechanical properties and oxidation behavior are also compared with the most recent Ni-based superalloys. This composite represents an excellent basis for the development of advanced Nb-based intermetallic matrix composites that offer improved properties over Ni-based superalloys at temperatures in excess of 1000 °C.

A haptic interaction method for volume visualization

Abstract: Volume visualization techniques typically provide support for visual exploration of data, however additional information can be conveyed by allowing a user to see as well as feel virtual objects. We present a haptic interaction method that is suitable for both volume visualization and modeling applications. Point contact forces are computed directly from the volume data and are consistent with the isosurface and volume rendering methods, providing a strong correspondence between visual and haptic feedback. Virtual tools are simulated by applying three-dimensional filters to some properties of the data within the extent of the tool, and interactive visual feedback rates are obtained by using an accelerated ray casting method. This haptic interaction method was implemented using a PHANToM haptic interface.

Local communication network for power reduction and enhanced reliability in a multiple node tracking system

Abstract: A mobile local area network (LAN) of tracked assess utilizing minimal power and bandwidth allows a large number of assets to be tracked in a practical manner. The mobile LAN is established between a plurality of tracking units in close proximity. Assets are approximately located according to their connection in the mobile LAN where the exact location of at least one of the network nodes is known. Each tracked asset has capability to independently determine and report its position to a central station, and each asset also has capability to communicate locally with other cooperative assets via the LAN. The LAN is dynamically reconfigurable so that as other cooperative assets come into proximity, they can join the network, and as others move away, they can leave the network. Within the network, a protocol is followed which assigns one of the assets to be the "master" and all others to be "slaves". The master asset takes responsibility for determining its own exact geographical position via LORAN, OMEGA, Global Positioning System (GPS) or ocher navigational aid. When connected in a LAN, slave assets report their ID to the master asset and do not determine their own locations in order to conserve power. The master reports its location and ID, as well as the IDs of the other assets in the LAN, to the central station. Uncertainty in the location of a slave asset is limited by the known possible geographical extent of the LAN which is known a priori.

A new approach to on-line turn fault detection in AC motors

Abstract: Turn fault detection is based on the principal that symmetrical (unfaulted) motors powered by symmetrical multiphase voltage sources will have no negative sequence currents flowing in the leads. A turn-to-turn fault will break that symmetry and give rise to a negative sequence current which may then be used as a measure of fault severity or to initiate protective action such as a circuit breaker trip. A new way of looking at the effects of turn faults has been developed that improves sensitivity and speed while reducing the probability of misdetection, taking into account voltage balance, load or voltage variation and instrument errors. The method has been implemented on a PC and tested, in real time, on a specially prepared small motor. Reliable detection of one shorted turn out of 648 turns per phase (in a Y connected motor) was demonstrated with the fault indicator becoming fully developed in two cycles of line frequency after initiation of the fault.

Focused ultrasound surgery system guided by ultrasound imaging

Abstract: A system employing ultrasound imaging as a method to localize a patient's tissue volume to be treated prior to applying therapeutic levels of ultrasound energy includes a therapy transducer for producing high-intensity fields that cause necrosis and an imaging transducer for producing high-quality ultrasound images. The therapy transducer is a spheroidal piezoelectric element and the imaging transducer is made up of a plurality of piezoelectric elements mounted in fixed relationship to the therapy transducer. The therapy transducer transmits a beam that is focused at a location in the tissue to be treated. The imaging transducer is then steered to produce successive receive beams which scan the tissue, including the tissue at the focal point of the pulsed therapy transducer. The image of the focal point is then superimposed on an image of the tissue to be treated obtained by B-mode imaging using the imaging transducer to transmit and then receive. Proper alignment of the focal point and the tissue to be treated ensures proper positioning of the therapy transducer relative to the patient.

Use of mutter mode in asset tracking for gathering data from cargo sensors

Abstract: The condition and/or integrity of goods is monitored while in transit using a local area network of tracked assets. Autonomous electronic sensors are situated in proximity to the cargo being shipped. These sensors communicate with an asset tracking unit affixed to the container for the goods via a mutter mode transceiver. The tracking unit has the ability to relay the cargo sensor data to the central station on demand, on exception, or on a predetermined schedule established by the central station. Communication between the cargo sensors and the tracking unit may be one-way (i.e., sensor to tracking unit) or two-way. Multiple sensors may communicate with each tracking unit.

Power electronic interface circuits for batteries and ultracapacitors in electric vehicles and battery storage systems

Abstract: A method and apparatus for load leveling of a battery in an electrical power system includes a power regulator coupled to transfer power between a load and a DC link, a battery coupled to the DC link through a first DC-to-DC converter and an auxiliary passive energy storage device coupled to the DC link through a second DC-to-DC converter. The battery is coupled to the passive energy storage device through a unidirectional conducting device whereby the battery can supply power to the DC link through each of the first and second converters when battery voltage exceeds voltage on the passive storage device. When the load comprises a motor capable of operating in a regenerative mode, the converters are adapted for transferring power to the battery and passive storage device. In this form, resistance can be coupled in circuit with the second DC-to-DC converter to dissipate excess regenerative power.

Quantitative Prediction of Environmentally Assisted Cracking

Abstract: It has long been recognized that the stress corrosion cracking (SCC) and corrosion fatigue cracking susceptibility of various alloy and environment systems is dependent upon complex interactions between stress, material, and environmental parameters. This complexity can lead to scatter in cracking responses that, in turn, leads to difficulty in predicting the life of engineering structures. F.P. Ford was the 1995 recipient of the W.R. Whitney Award sponsored by NACE International. The present work is taken from his award lecture at CORROSION/95 held in March 1995 in Orlando, Florida. His lecture focused on how these interactions may be predicted quantitatively for ductile alloys in aqueous environments with knowledge of the cracking mechanism. This capability may lead to life prediction of critical structures in, for instance, boiling-water nuclear reactors (BWR).

System for managing multiple projects of similar type using dynamically updated global database

Abstract: A system for managing multiple projects of a similar type has a global project management database for storing data for all participating projects which is dynamically updated with best current data representing best current practices across all participating projects in the system. Localized computer terminals are operated at each local site with a common project management program and data imported from the global project management database. Periodically, the local terminals export data to the global project management database which are evaluated to determine any new best current practices across all participating projects and to update the global project management database with the new best current practices. Upon periodically importing data from the global project management database, each localized computer terminal is updated with the new best current practices across all participating projects.

Flexible interconnect film including resistor and capacitor layers

Abstract: A method for fabricating a flexible interconnect film includes applying a resistor layer over one or both surfaces of a dielectric film; applying a metallization layer over the resistor layer with the resistor layer including a material facilitating adhesion of the dielectric film and the metallization layer; applying a capacitor dielectric layer over the metallization layer; and applying a capacitor electrode layer over the capacitor dielectric layer. The capacitor electrode layer is patterned to form a first capacitor electrode; the capacitor dielectric layer is patterned; the metallization layer is patterned to form a resistor; and the metallization layer and the resistor layer are patterned to form an inductor and a second capacitor electrode. In one embodiment, the dielectric film includes a polyimide, the resistor layer includes tantalum nitride, and the capacitor dielectric layer includes amorphous hydrogenated carbon or tantalum oxide. If the resistor and metallization layers are applied over both surfaces of the dielectric film, passive components can be fabricated on both surfaces of the dielectric film. The dielectric film can have vias therein with the resistor and metallization layers extending through the vias. A circuit chip can be attached and coupled to the passive components by metallization patterned through vias in an additional dielectric layer.

Power management control system

Abstract: The power management control system comprises a computer having standard RS485 interface cards and adapters installed in its I/O slots defining multiple industry standard Modbus RTU networks. The computer contains software for monitoring and controlling selected aspects of power usage/consumption, as described in more detail hereinafter. The Modbus RTU protocol is a well known industry standard. Devices with a Modbus RTU interface can be connected directly to the Modbus and other devices which communicate on the Commnet protocol require a Modbus concentrator. The Modbus concentrator provides an interface between the Modbus RTU protocol and the Commnet protocol, whereby these other devices can communicate through the Modbus concentrator over the Modbus. Alternatively, standard Ethernet interface cards and adapters are installed in the computer's I/O slots defining multiple standard Ethernet TCP/IP networks. The Ethernet TCP/IP protocol is a well known standard, which would allow a user of the power management control system of the present invention to use its existing LAN. Ethernet gateways are connected to the Ethernet TCP/IP networks to provide an interface between the Ethernet TCP/IP protocol and the Modbus RTU protocol.

High-temperature refractory metal-intermetallic composites

Abstract: In this article, toughness, oxidation, and rupture behaviors of present-generation refractory metal-intermetallic composites are compared to the performance requisites necessary to make these materials a competitive choice for the jet engine turbine environment of the future.

Optimization of spoiled gradient‐echo phase imaging for in vivo localization of a focused ultrasound beam

Abstract: The parameters of a spoiled gradient-echo (SPGR) pulse sequence have been optimized for in vivo localization of a focused ultrasound beam. Temperature elevation was measured by using the proton resonance frequency shift technique, and the phase difference signal-to-noise ratio (SNR delta phi) was estimated in skeletal muscle and kidney cortex in 10 rabbits. Optimized parameters included the echo time equivalent to T2* of the tissue, the longest repetition time possible with a 20-s sonication, and the flip angle equivalent to the Ernst angle. Optimal SPGR phase imaging can detect a sonication beam with a peak phase difference of 0.55 radian, which corresponds to a temperature elevation of 7.3 degrees C. The sonication beam can be localized within one voxel (0.6 x 0.6 x 5 mm3) at power levels that are below the threshold for thermal damage of the tissue.

Railcar location using mutter networks and locomotive transmitter during transit

Abstract: A method of tracking railcars in transit using global positioning techniques involves determining the location of a railcar by using a Global Positioning System (GPS) receiver and a satellite transceiver on board the locomotive, and a local area network of railcar tracking units. Instead of computing the GPS solution independently and transmitting it to a central station, the railcar tracking units transmit their unique identifications (IDs) to one of the tracking units in the local area network acting as an administrator tracking unit. The administrator tracking unit maintains a list of IDs and periodically transmits the list of IDs to the locomotive. The locomotive locates itself using the GPS system and periodically transmits its position and velocity to the central station.

Self-Calibration from Image Triplets

Abstract: We describe a method for determining affine and metric calibration of a camera with unchanging internal parameters undergoing planar motion. It is shown that affine calibration is recovered uniquely, and metric calibration up to a two fold ambiguity.

Thermal barrier coating resistant to erosion and impact by particulate matter

Abstract: A thermal barrier coating adapted to be formed on an article subjected to a hostile thermal environment while subjected to erosion by particles and debris, as is the case with turbine, combustor and augmentor components of a gas turbine engine. The thermal barrier coating is composed of a metallic bond layer deposited on the surface of the article, a ceramic layer overlaying the bond layer, and an erosion-resistant composition dispersed within or overlaying the ceramic layer. The bond layer serves to tenaciously adhere the thermal insulating ceramic layer to the article, while the erosion-resistant composition renders the ceramic layer more resistant to erosion. The erosion-resistant composition is either alumina (Al 2 O 3 ) or silicon carbide (SiC), while a preferred ceramic layer is yttria-stabilized zirconia (YSZ) deposited by a physical vapor deposition technique to have a columnar grain structure.

Bidirectional buck boost converter

Abstract: A bidirectional buck boost converter and method of operating the same allows regulation of power flow between first and second voltage sources in which the voltage level at each source is subject to change and power flow is independent of relative voltage levels. In one embodiment, the converter is designed for hard switching while another embodiment implements soft switching of the switching devices. In both embodiments, first and second switching devices are serially coupled between a relatively positive terminal and a relatively negative terminal of a first voltage source with third and fourth switching devices serially coupled between a relatively positive terminal and a relatively negative terminal of a second voltage source. A free-wheeling diode is coupled, respectively, in parallel opposition with respective ones of the switching devices. An inductor is coupled between a junction of the first and second switching devices and a junction of the third and fourth switching devices. Gating pulses supplied by a gating circuit selectively enable operation of the switching devices for transferring power between the voltage sources. In the second embodiment, each switching device is shunted by a capacitor and the switching devices are operated when voltage across the device is substantially zero.

Protocol and mechanism for primary and mutter mode communication for asset tracking

Abstract: A mode of communication for asset tracking units involves communication between a central station and the individual tracking units, usually through a satellite link. This mode is the primary communication link for tracking the assets. A second mode is the local area network (LAN) or "mutter" mode, in which a subset of tracking units communicate with each other in a mobile LAN. This mode is used as the secondary communication mechanism to conserve power, since mutter mode communication requires much less energy for local communication between the tracking units as opposed to direct satellite communication with the central station. In addition, mutter mode leads to increased reliability of the asset tracking system by enabling tracking of units which have batteries too weak to support communication with the central station, but strong enough to support communication in mutter mode. The mutter mode is also useful in finding tracking units which are not communicating with the central station due primary communication equipment fault or other inhibiting condition.

Floating vane turbine nozzle

Abstract: A turbine nozzle includes outer and inner bands having respective mounting holes therein. A plurality of vanes extends through respective pairs of outer and inner holes in the bands. The vane outer and inner ends are resiliently supported to the bands to allow differential thermal movement therebetween so that the individual vanes float relative to the outer and inner bands to prevent thermal stress failure thereof.

Dynamic data exchange server

Abstract: A dynamic data exchange (DDE) server which allows external programs to access power management data is presented. The DDE server provides a mnemonic cross reference between register items and standardized, alphanumeric parameter names. This mnemonic interface allows the user to retrieve data from a device without knowledge of the actual device register item number. Also, the DDE server automatically performs time synchronizing for all supported devices and provides a consistent waveform and event interface. The DDE server is optimized for either the Modbus RTU or Ethernet protocol. The DDE server includes toolkit functions which are used to maintain DDE communication and protocol timers and to maintain active topic and item lists. The DDE server acts as a link between a client requesting device data and a field device which can provide the data. The DDE server communicates to the field device through communication ports and to the client via DDE message link. A client sends its requests to server to read/write some device registers. The server maps each request to suitable device read/write request packets and carries out the necessary transaction with device. Then it relays the result back to the client after processing and casting the collected device data to proper format.

Thermal barrier coatings having an improved columnar microstructure

Abstract: An article having a spallation resistant TBC comprises a metal substrate, such as a high temperature superalloy, and a TBC, such as a coating of yttria stabilized zirconia. The TBC comprises a plurality of plasma-sprayed layers. The TBC has a coherent, continuous columnar grain microstructure, wherein at least one layer has a plurality of continuous columnar grains which have been extended by directional solidification into an adjacent layer. In a preferred embodiment, the coherent, continuous columnar microstructure comprises substantially all of the volume of TBC. A coherent, continuous columnar grain microstructure is also taught wherein at least some of the plurality of coherent, continuous columnar grains which comprise a TBC extend through essentially the entire thickness of the coating. A columnar crack pattern of cracks extending generally normal to the surface of the metal substrate is also developed within TBCs of the present invention in conjunction with the coherent, continuous columnar grain microstructures described.

SiC Power Devices

Abstract: The present status of SiC high-voltage power switching devices is reviewed. The figures of merits that have been used for unipolar and bipolar devices to quantify the intrinsic performance improvement over silicon are presented. Analytical and numerical modeling and simulations to estimate the BV and device choice are described. The active area and termination design of trenched-gate MOS power transistors, together with an integrated process for their fabrication, is presented. The progress in high-voltage power device experimental demonstration is described. The material and process technology issues that need to be addressed for SiC device commercialization are discussed. Finally, the impact of SiC power devices on motor drive systems is estimated.

Probing the Microscopic Molecular Environment in Liquids: Intermolecular Dynamics of CS2 in Alkane Solvents†

Abstract: The femtosecond optical-heterodyne-detected optical Kerr effect/Raman-induced Kerr effect (OHD OKE/RIKE) dynamics of CS2 dissolved in a series of alkane solvents are reported. The data reveal that the nondiffusive (subpicosecond) dynamics of simple molecular liquids are determined largely by the details of the local, microscopic environment, rather than by the bulk solution properties, with no correlation observed between the short-time, nondiffusive dynamics and the bulk solution viscosity. For each solvent investigated, the vibrational spectral density is observed to narrow and shift to lower frequency with increasing dilution. While the same general trend is observed for each solvent, deviations of magnitude are observed for the longer-chain n-alkanes. This, coupled with the markedly nonexponential decay of the orientational anisotropy observed for the higher-alkane dilutions, suggests the presence of two distinct environments in which isolated pockets of CS2 exist. The observed spectral evolution is d...

Cooling joint connection for abutting segments in a gas turbine engine

Abstract: A seal joint including a sealing member for sealing segmented components of a gas turbine engine is spaced from the gas path to provide more effective cooling. The segments include radial extension flanges spacing the seal joint from the gas path. Various cooling arrangements are adaptable to the modified segments to provide for open or closed circuit impingement or convection cooling plus film cooling. Excessive thermal gradients are avoided as the entire corner of the segment is evenly cooled. Moreover, air usage at the joint is bounded by seal leakage with no extra dedicated cooling air.