Showing papers by "General Electric published in 1977"

Flow-Induced Vibration

Abstract: This book focuses on applications for offshore platforms and piping; wind-induced vibration of buildings, bridges, and towers; and acoustic and mechanical vibration of heat exchangers, power lines, and process ducting. Numerous examples drive home the reality of the practical problems encountered here. More than 200 figures and 20 tables complement the text by providing such data as damping factors, lift coefficients, and the formulas needed to apply practical methods directly to a wide range of structures, from heat exchangers to hypersonic aircraft. Devoted to the analysis and prediction of flow-induced vibrations, this volume will prove of immense interest to mechanical, civil, nuclear, marine, structural, and electrical engineers; physicists, designers, and naval architects; and people working in the construction and petroleum industries, power plants, power transmission, ship building, nuclear power, energy production, and defense engineering.

Electronically commutated motor

Abstract: A brushless DC motor is constructed with photosensitive device for detecting rotor shaft position. Arcuate permanent magnets on the rotor provide a DC flux field while distributed stationary armature windings, each spanning a fixed number of slots in the armature assembly, provide mutually perpendicular magnetic fields. A logic circuit comprising NOR gates and transistor switches and drivers activated in response to signals from the shaft position sensors are utilized to control current switching in the armature windings of the motor. A light interrupting shutter mounted to the rotor cooperates with the light sensitive devices which are mounted to a supporting bracket fixed to the stationary armature assembly in a manner to selectively preset advancement of commutation of the armature windings. Variations on permanent magnet rotor construction and novel applications of a brushless DC motor are also disclosed as is a novel approach for dispensing with the mechanism for detecting the shaft position. In this last respect a commutating circuit is disclosed for a brushless DC motor, including a detecting circuit responsive to the electromotive force (emf) of the brushless DC motor to provide a simulated signal indicative of the rotation of the motor's shaft and a logic circuit responds to the output of the shaft position detecting circuit to control the application of driving signals through the armature windings of the DC brushless motor.

An analysis of several heuristics for the traveling salesman problem

Abstract: Several polynomial time algorithms finding “good,” but not necessarily optimal, tours for the traveling salesman problem are considered. We measure the closeness of a tour by the ratio of the obtained tour length to the minimal tour length. For the nearest neighbor method, we show the ratio is bounded above by a logarithmic function of the number of nodes. We also provide a logarithmic lower bound on the worst case. A class of approximation methods we call insertion methods are studied, and these are also shown to have a logarithmic upper bound. For two specific insertion methods, which we call nearest insertion and cheapest insertion, the ratio is shown to have a constant upper bound of 2, and examples are provided that come arbitrarily close to this upper bound. It is also shown that for any n≥8, there are traveling salesman problems with n nodes having tours which cannot be improved by making n/4 edge changes, but for which the ratio is 2(1−1/n).

Group Combustion of Liquid Droplets

Abstract: Quasi steady “external group combustion” of droplet cloud with non-uniform droplet size distributions has been developed to assess the group burning behavior of fuel sprays in industrial and jet engine combustors. The exact solutions for the perturbation equation for power law droplet size distributions are obtained. Numerical analysis pertaining to the initial phase of group combustion with mean droplet size approximation is also presented. The study reveals that current spray burners are operating at high group combustion number regime, wherein the burning mechanism coincides with external group burning mode as previously predicted by Suzuki and Chiu. A spray with a higher group combustion number is also featured by a “sheath vaporization” which is localized in a thin layer located in the outermost region of the cloud. Sprays at lower group combustion number regime cease to burn with external combustion modes when the group combustion number is less than the critical value which is determined b...

Optimal power dispatchߞA comprehensive survey

Abstract: This paper reviews the progress of optimal dispatch, also called economic dispatch, since its inception to the present in chronological sequence. The classic single area as well as multiarea cases are summarized, and the important theoretical work in optimal load flows suggested to date reviewed. Approaches to the optimal load flow taken by industry are also reported, as well as an itemization of problems that still remain to be solved.

Transformation of the state of nitrogen in diamond

Abstract: High temperature–high pressure annealing experiments on diamond transform type IB dispersed nitrogen into type IA aggregate nitrogen. The activation energy for the transformation is approximately 60 kcal mol−l (2.6 eV). An estimate is given for the diffusivity of nitrogen in diamond for this transformation

The Block Lanczos Method for Computing Eigenvalues

Abstract: In this paper, we describe a Block Lanczos method for computing a few of the least or greatest eigenvalues of a sparse symmetric matrix. A basic result of Kaniel and Paige describing the rate of convergence of Lanczos' method will be extended to the Block Lanczos method. The results of experiments conducted with this method will be presented and discussed.

Lightning Protection of Aircraft

Abstract: The current knowledge concerning potential lightning effects on aircraft and the means that are available to designers and operators to protect against these effects are summarized. The increased use of nonmetallic materials in the structure of aircraft and the constant trend toward using electronic equipment to handle flight-critical control and navigation functions have served as impetus for this study.

Magnetic anneal anisotropy in amorphous alloys

Abstract: The uniaxial magnetic anisotropy K u induced by a magnetic anneal has been determined, after stress relief, for a series of alloys given by (Fe y Ni 1-y ) 80 B 20 . For all of these alloys K u depends on anneal temperature as predicted by directional order theory. The concentration dependence of K u in these alloys is also consistent with directional order theory. The maximum K u , corrected for its temperature dependence, occurs at the composition y = 0.5 . However, K u does not fall to zero at y = 1 as predicted if directional order is assumed to arise only from Fe-Ni pair ordering. These results are interpreted as suggesting a role of the glass former, boron, in the directional ordering, perhaps as an "interstitial." The interaction energy derived from the results is negative as expected for interactions leading to precipitation. Its large value of \approx -7.5 \times 10^{-14} ergs corresponds to a critical temperature for precipitation of 3000 K.

Comparison of gold, platinum, and electron irradiation for controlling lifetime in power rectifiers

Abstract: Recombination statistics based upon a single dominant level have been used to predict the relative characteristics of gold-diffused, platinum-diffused, and electron-irradiated silicon power rectifiers and thyristors. These calculations indicate that gold-diffused devices will have the best trade-off curve between forward voltage drop and reverse recovery time, while exhibiting the highest leakage currents. Electron-irradiated devices are predicted to have the worst trade-off curve among the three cases and twice the leakage current of platinum-diffused devices. The leakage current of platinum-diffused devices is shown to be an order of magnitude lower than gold-diffused devices. The measured characteristics of gold-diffused, platinum-diffused, and electron-irradiated power rectifiers are shown to be in good agreement with these calculations. The results are also shown to be applicable to power thyristors.

A general method for determining resonances in transformer windings

Abstract: This paper presents a method for calculating terminal and internal impedance versus frequency for a lumped parameter model of a transformer The transformer's total frequency response can be accurately determined from this impedance data directly, ie, the terminal resonance and anti-resonance and internal amplification factor characteristic can be calculated for a single or three-phase transformer model Since most equipment associated with power system operation can be accurately modeled with lumped parameter networks, this method also provides an accurate, straightforward method for determining the resonance characteristic of those systems An additional significance of this method is that the accuracy of the calculation is limited only by the user's ability to represent the equipment or system Heretofore, the accuracy of this calculation was limited by the simplifying assumptions required of the network model by each solution method This paper presents the definitions and mathematical theory underlying the method Two examples are presented in which comparisons are made between measured and calculated values for a helical air core coil and a 200 MVA single-phase autotransformer The agreement is excellent

Cooling air cooler for a gas turbofan engine

Abstract: An air-to-air heat exchanger is provided for a gas turbofan engine to significantly reduce the quantity of cooling air that is presently needed to effectively cool the hot turbine parts. Typically, the turbine is internally cooled with air bled from the compressor which, though cooler than the turbine, has been heated due to the work done on it by the compressor. In accordance with the present invention, the heat exchanger is located internally of the bypass duct to place in heat exchange relationship a captured portion of the relatively cool bypass flow and this warmer compressor bleed air, thereby cooling the turbine coolant and significantly reducing the amount of such coolant required. This results in a decrease in engine specific fuel consumption.

Nuclear fuel element

Abstract: A nuclear fuel element for use in the core of a nuclear reactor is disclosed and has an improved composite cladding comprised of a moderate purity metal barrier of zirconium metallurgically bonded on the inside surface of a zirconium alloy tube. The metal barrier forms a shield between the alloy tube and a core of nuclear fuel material enclosed in the composite cladding. There is a gap between the cladding and the core. The metal barrier forms about 1 to about 30 percent of the thickness of the composite cladding and has low neutron absorption characteristics. The metal barrier serves as a preferential reaction site for gaseous impurities and fission products and protects the alloy tube from contact and reaction with such impurities and fission products. Methods of manufacturing the composite cladding are also disclosed.

Gaseous hydrogen embrittlement of high strength steels

Abstract: The kinetics of sustained-load subcritical crack growth in hydrogen were determined for 18Ni(200) and 18Ni(250) maraging steels over a range of hydrogen pressures and temperatures. Crack growth in each steel was characterized by an apparent threshold stress intensity, a domain where the growth rate increased sharply with stress intensity (K) (Stage I), and a range where the growth rate was independent ofK (Stage II). The rate-limited Stage II crack growth in these steels exhibited three distinct regions of temperature dependency, with a different isothermal pressure dependence in each region. In the low temperature region, Stage II crack growth was thermally activated with δH = 18.2 ±1.7 kj/mol; (δH being independent of hydrogen pressure and yield strength). The growth rates at a givenK were proportional to the square root of hydrogen pressure. In the intermediate temperature region, Stage II growth rates increased at slower rates, passed through a maximum and then decreased with increasing temperature. Within this region, the pressure dependence for crack growth increased from 1/2-power to 2.0-power with increasing temperature. Above a transition temperature, each grade of maraging steel became essentially immune to gaseous hydrogen embrittlement for the hydrogen pressure range considered. The transition temperature was strongly affected by yield strength and hydrogen pressure. Plausible explanations for these phenomenological results are considered.

Method for fabricating a rotary drill bit and composite compact cutters therefor

Abstract: A method for fabricating a drill bit comprising a plurality of composite compact cutters by furnace brazing each cutter in a recess in the crown of the drill bit. In one embodiment, each cutter is comprised of a mass of bonded polycrystalline abrasive, a substrate bonded to said abrasive mass and a thin layer of brazing filler metal coating the exposed surface of the substrate. In another embodiment, the cutter comprises a composite compact cutter blank bonded to one end of a cemented carbide pin, and a thin layer of brazing filler material coating the substrate of the blank and the carbide pin. In both embodiments, the coating of brazing filler metal is applied to the cutters by dipping in a molten bath of the filler metal.

Modeling and Design of Controlled Current Induction Motor Drive Systems

Abstract: A dynamic model for current-controlled induction motor drives is developed, and a transfer function approach to the transient response investigation is formulated by means of d-q variables in the synchronously rotating reference frame. A sample control strategy is discussed, and transfer functions for various combinations of input and output variables are presented. It is shown that both dynamic and static instabilities exist for open-loop operation, but a well-damped closed-loop response is possible if slip frequency and current magnitude control are imposed. A comparison between the analytical transfer function transient performance predictions, the transient respontse predicted by the hybrid computer simulation, and actual laboratory tests is made using frequency response techniques. Bode plots are used to correlate' the results between laboratory and analytical techniques. Hybrid computer and laboratory results are presented to show typical steady-state characteristics and waveforms.

Electronic display apparatus

Abstract: In a television receiver there are provided means for decoding and displaying data received in coded form either on a television carrier signal during field blanking periods or over a telephone line, the decoding means and the display means being interconnected by way of multiconductor data and address highways or buses. Data storage and data processing means, and also other data input means may be connected to these highways.

Theory and breakdown voltage for planar devices with a single field limiting ring

Abstract: The use of one or more floating field limiting rings reduces the adverse effect of junction curvature on the breakdown voltage in planar devices. Although this has been known for some time, there has not been a way of accurately predicting the amount of improvement that can be achieved using field rings. In this paper, a computer algorithm is presented which makes it possible to perform field calculations on devices with floating field rings. In addition, a normalized curve is presented which shows the relative improvement that a single optimally placed field ring has on the breakdown voltage for any planar device. The basis of the construction of this curve is the use of a normalized radius of curvature which is a precise measure of the effect of curvature for any device. The theoretical predictions are compared with experiments for over 640 devices encompassing 16 different field ring locations. Good agreement is achieved between theory and experiment.

A new concept in station arrester design

Abstract: In 1968 Matsushita Electric Industrial Co of Osaka, Japan announced a new improved non-linear resistance material based on zinc oxide The original devices were small low voltage units applicable for use in the electronics industry In 1970 work was performed by the General Electric Co, and is continuing, using its own funds and technical resources, to develop larger devices for use as a substitute for silicon carbide valve blocks in surge arresters Development has now progressed to the point where this material, with non-linearity characteristics far superior to silicon carbide, can be used to manufacture station type arresters which do not employ series gaps The purpose of this paper is to outline some of the characteristics made possible by the new material which is becoming increasingly important to the electrical industry

Diagnostic method employing a mixture of normally separable protein-coated particles

Abstract: A mixture of two different kinds of particles having distinctive, different properties is employed for determining the presence of a select protein in, or the absence of a select protein from, a solution. The first kind of particle provides a property facilitating separation, while the second kind of particle provides a property facilitating detection. The particles are coated with the same protein, a protein able to interact specifically with the select protein.

Reconstruction of Ultrasound Propagation Speed Distributions in Soft Tissue: Time-Of-Flight Tomography

Abstract: A soft tissue imaging/characterization technique is described which is based on computerized reconstruction of twodimensional velocity distributions from one-dimensional time-of-flight (TOF) projections. The projection data are obtained by measuring short-pulse propagation delay from transmitter to receiver along many paths through the specimen. The velocity reconstruction provides a true measure of bulk tissue properties and is presented in both digital and video display formats. The concept is demonstrated with results on phantoms and beef liver as well as live human breasts.

Flame retardant composition of polyphenylene ether, styrene resin and cyclic phosphonate

Abstract: Flame retardant compositions comprising a polyphenylene ether resin, a styrene resin and a cyclic phosphonate have excellent appearance and physical properties after molding. Especially useful is diphenyl pentaerythritol diphosphonate.

Patient positioning indication arrangement for a computed tomography system

Abstract: A computed tomography system has an arrangement for indicating the staged position of a patient in relation to the location of a first scan by the system. The arrangement includes at least one energy beam source, such as a laser, which projects a visible pattern on the surface of the patient. The pattern corresponds to the central alignment of the system and to the location of the first scan of the system when a patient-supporting table is subsequently translated into a gantry of the system for x-ray examination. The pattern includes a central longitudinal line indicating a central longitudinal plane of the area to be scanned, and a transverse line indicating the location of the transverse plane of the first scan. The energy beam source of the arrangement is adjustable to project an angled line which corresponds to a tilted gantry or a tilted patient, or a tilted supporting table to indicate the location of the transverse plane of the first scan of the system. The patient is aligned and located in agreement to the projected patterns to thereby properly position the patient for the subsequent desired first scan by the system.

Ultrasonic multi-sector scanner

Abstract: A steered beam B-scan ultrasonic imaging system has a linear transducer array divisible into multiple sub-arrays of transducer elements each operable to perform a sector scan, with the origin points displaced longitudinally along the array between sector scans. The system performs overlapping sector scans and is capable of imaging randomly oriented specularly reflecting targets. Time delays in the transmitting and receiving channels to steer the transmitted beam and to focus the received echoes are provided by digital techniques, by reversible digital shift registers, or by charge coupled device delay lines. The multiple sector image is displayed in real time in an intensity versus displacement format on a cathode ray tube.

Liquid crystal materials

Abstract: Liquid crystal polymers, which may be used for optical information storage, either alone or in mixture with other liquid crystals, are of the general formula ##STR1## wherein the mesogenic grouping M has a general structure ##STR2## wherein the rings P and Q are selected from phenyl, trans-cyclohexyl, pyridyl, pyrimidinyl, dioxanyl, and bicyclo (2.2.2) octyl. The rings P and/or Q may carry lateral substituents, preferably Me or F. The general structure of Formula (I) may represent a homopolymer or a copolymer.

High-Frequency Link Power Conversion

Abstract: A class of electrical power conditioners incorporating an intermediate variable high-frequency link concept is introduced by considering a converter with dc source and variable voltage and frequency polyphase output, then extending the concept to polyphase ac source voltage The ac 60 Hz -ac high-freq -ac output-freq system is essentially comprised of two cascade 12-thyristor cycloconverters separated by a parallel resonant tank circuit The tank circuit provides commutation means for both cycloconverters Normally, the input cycloconverter operates in the inverting mode and the output cycloconverter in the rectifying mode, although during regeneration their roles are reversed For static var control applications, the output cycloconverter is not required The input cycloconverter separating the 60-Hz supply from the resonant tank circuit can be envisioned as a ``solid-state synchronous machine'' capable of controlling real and reactive power independently Various control strategies for doing this is discussed The design and potential performance characteristics for a 50-kVA system suitable for motor drives is illustrated with regard to power capability and tank frequency versus tank-to-supply voltage radio, input power factor setting, load voltage, and power factor