Showing papers by "Westinghouse Electric published in 1973"

Relation Between Strength, Fracture Energy, and Microstructure of Hot-Pressed Si3N4

Abstract: A fracture mechanics approach was used to investigate the high strength of hot-pressed Si3N4. Room-temperature flexural strengths, fracture energies, and elastic moduli were determined for material fabricated from α- and β-phase Si3N4 powders. When the proper powder preparation technique was used, α-phase powder resulted in a high fracture energy (69,000 ergs/cm2), a high flexural strength (95,000 psi), and an elongated (fiberlike) grain morphology, whereas β-phase powder produced a low fracture energy (16,000 ergs/cm2), a relatively low strength (55,000 psi), and an equiaxed grain morphology. It was hypothesized that the high strength of Si3N4 hot-pressed from α-phase powder results from its high fracture energy, which is attributed to the elongated grains. High-strength Si3N4 has directional properties caused, in part, by the elongated grain structure, which is oriented preferentially with respect to the hot-pressing direction.

Electrostatically deflectable light valve with improved diffraction properties

Abstract: An electrostatically deflectable light valve adapted for use in an array for producing television pictures as a projected image upon a large display screen. The light valve structure is such that a plurality of reflective wing portions are free to be deflected along directional axes which are at an angle to the prime directional axes of the overall array, so that light which is predominantly diffracted along the array axes may be decoupled or separated from the signal light produced by activated light valves and used to project the image. The contrast ratio of signal light to background light for the system is significantly improved, using this method of discrimination.

Effect of Microstructure on Strength of Si3N4‐SiC Composite System

Abstract: The Si3N4-SiC composite system was investigated to better understand the effect of microstructure on the strength-controlling factors, i.e. fracture energy, elastic modulus, and crack size. Silicon carbide dispersions with average particle sizes of 5, 9, and 32 μm were used to form 3 composite series within this system, each containing 0.10, 0.20, 0.30, and 0.40 vol fraction of the dispersed phase. These composites were fabricated by hot-pressing. Fracture energy and strength values were measured for each composite. A linear relation between the elastic modulus of the two phases was assumed. The crack size was calculated for each composite using the appropriate property values. The strength behavior of the 9- and 32-μm series was controlled by the crack size, which, in turn, was controlled by the particle size and volume fraction of the SiC phase. Particle size and volume fraction did not affect the crack size of the 5-μm series, in which strength was controlled by both fracture energy and elastic modulus. Strengths measured at 1400°C and thermal conductivity measurements indicate that several of these composites are promising as high-temperature structural materials.

A 6 × 6 inch 20 lines-per-inch liquid-crystal display panel

Abstract: An integrated 14 000 picture element 36-in2flat screen display panel has been constructed by a combination of thin-film transistor and nematic liquid-crystal technology. The design, fabrication, and present performance of the panel is discussed. The design of the peripheral circuits, which permit the presentation of low resolution off-the-air TV pictures on the panel is described in another paper.

Training simulator for a nuclear power plant

Abstract: A training simulator for the full-scope real-time dynamic operation of a nuclear power plant utilizes apparatus that includes control consoles having manual and automatic devices for operating simulated plant components and indicating devices for monitoring physical values in the simulated plant. A general purpose digital computer configuration is connected to the control consoles to accept input data indicative of the operated condition of the console control devices and perform dynamic real-time simulation calculations for providing output data to the monitoring devices. An instructor's console, which has control and indicating devices, is connected to the computer configuration to perform functions that include initializing and "replaying" selected operational states of the simulated plant. The majority of the control components of the simulated plant, such as valves, pumps and controllers, are simulated separately from the simulated system they control. The computer organization is structured to perform a combination of sequential data processing at predetermined repetitive time intervals; and to perform event oriented data processing with the capability of recognizing and processing data immediately upon the occurrence of an event. When the simulated plant is initialized or "replayed," the computer functions provide indications of the plant control devices which do not positionally correspond to the plant status. A plural digital computer arrangement is disclosed wherein the data in each computer is processed by its own control arrangement; and the interdependent data is synchronized by the control function on one computer and data link communication between computers.

Pollutant Detection by Absorption Using Mie Scattering and Topographic Targets as Retroreflectors

Abstract: Remote pollutant measurement by absorption using topographical reflectors or atmospheric Mie scattering as a distributed reflector offers increased range and sensitivity compared to that achieved by Raman or resonance backscattering methods. The use of topographical reflectors offers the advantage of a single-ended absorption measurement for ranges up to 10 km and sensitivities to less than 0.01 ppm for a 10-mJ, 100-nsec transmitted pulse. The distributed Mie reflector permits absorption measurements over a depth cτ/2, determined by the pulse length τ, and allows ranging by time-of-flight measurement. For a 100-mJ, 100-nsec pulse sensitivities to 0.3 ppm at a 15-m depth resolution to ranges of 1–4 km are possible. This sensitivity is 104 to 105 times better than that achieved by the Raman method.

Growth and Characterization of Polycrystalline Silicon

Abstract: Polycrystalline silicon is deposited by pyrolysis of silane in an rf heated epitaxial reactor. The grains exhibit a fibrous microstructure having an 〈110〉 preferred orientation in the growth direction. Growth is inhibited in the presence of excess arsine and accelerated in the presence of diborane. The results are explained in terms of catalysis and poisoning of surface adsorption sites responsible for reaction. A simple model for current conduction in polycrystalline silicon is described based on grain size, grain doping, and effective barrier height due to the grain boundary. This model satisfactorily explains the observed temperature dependence of the resistivity of undoped films and also the large values of resistivity which are observed for dopant concentrations .

The microstructure of hot-pressed silicon-nitride

Abstract: Grain morphology, distribution of impurities and inclusions, phases and dislocation structures in two grades of hot-pressed Si3N4 were investigated by means of replica and thin foil transmission microscopy, and by X-ray diffraction, microprobe and Auger analyses. High concentrations of impurities, specifically Ca, were detected at the grain boundaries. Fe-W-Si particles were seen within the grain. Non-densified Si3N4 inclusions were found to be detrimental to the strength. Possible correlations among strength, densification data and distribution of elements and phases are discussed.

Minimal structural response under random excitation using the vibration absorber

Abstract: The equations of motion are derived for the first mode response of a linear multistorey structure having a linear vibration absorber attached to the roof. Furthermore, the variance of the first mode response to a gaussian white noise lateral base acceleration (as a model of earthquake excitation) is determined. Smallest possible values of the variance of the response along with corresponding absorber parameters are established using an optimization program. It is demonstrated that the absorber is quite effective in reducing first mode response for 5- and 10-storey structures even with relatively small values of the absorber mass. Moreover, minimal responses for the randomly excited single-degree-of-freedom system have been determined, and a design example is presented. The absorber system has potential application not only in earthquake engineering but also in aerospace and terrestrial vehicle design.

Color video display system comprising electrostatically deflectable light valves

Abstract: A color video imaging system utilizing a cathode ray device with a target comprising an array of electrostatically deflectable light valves. The light valve structure and the arrangement of light valves as an array permits sequential activation of the light valves in response to a specific primary color video signal. The light valves are arranged in three element groupings, and a schlieren optical means is provided having respective primary color transmissive portions through which the light reflected from the deflected light valves is passed, to permit projection of a color image upon a display screen.

Particle-Initiated Breakdown Between Coaxial Electrodes in Compressed SF6

Abstract: The influence of conducting particles on the ac breakdown of compressed SF6 has been investigated for two coaxial systems having inner electrodes of diameter 75 mm and 150 mm and a 250 mm diameter outer electrode, using voltages up to 450 kV rms at pressures up to 1.8 MNm?2 (18 atm.). For filamentary particles of 0.1 mm or 0.4 mm diameter wire, there was a maximum breakdown voltage at 0.4 MNm?2 (4 atm.) which became more pronounced with increasing particle length and decreasing particle diameter. No maximum was observed with spherical particles but for each system there was a critical sphere size which gave the lowest breakdown voltage at a given pressure. There was also a slight density effect at the lower pressures, aluminum spheres producing lower breakdown voltages than spheres of brass or steel. Tests with wires and spheres fixed to the inner conductor, to simulate breakdown initiated by field enhancement at particles migrating to the inner, gave ac and impulse results which differed from the free-particle ac breakdown voltages. Calculations have been made of the motion of spherical particles and of the energy in microdischarges at the electrodes; the particles can make excursions lasting several cycles and this may be important in creating optimum conditions for breakdown.

Gas turbine and steam turbine combined cycle electric power generating plant having a coordinated and hybridized control system and an improved factory based method for making and testing combined cycle and other power plants and control systems therefor

Abstract: A combined cycle electric power plant includes in interconnected relationship a steam turbine, two gas turbines, three electric generators, two heat recovery steam generators, a hybrid computer control system, a plant protection system and various items of auxiliary equipment. A computerized simulator is interfaced with the control system at the factory site to test the controls and the control system is then modularly disassembled in various structures and shipped to the field site for reassembly without need for extensive field testing. The control system includes a digital control computer, a digital monitor computer and modular analog controls for the turbines. Various levels of automated control can be employed including coordinated plant control which involves supervisory operation of the analog controls by the control computer. In analog control, complete plant operation is produced by operation of the analog controls without the control computer.

Current saturation and small-signal characteristics of GaAs field-effect transistors

Abstract: The model previously proposed by Turner and Wilson is developed in detail and compared with experiment. Deviations from Shockley's classical theory can be accounted for in terms of a single quantity Γ, which is related to E m the peak field for GaAs. A discussion of the physical mechanism of current saturtation shows that the formation of domains within the channel is hampered in a conventional GaAs FET. A y -parameter analysis is presented that permits calculation of transconductance and the unity current gain frequency f T . Measurements of drain current, transconductance, and f T versus gate voltage all show good agreement with values predicted by the theory. Estimates are given which show that the current saturation mechanism described will be important in the design of GaAs microwave FET's.

Solid state radiation sensitive field electron emitter and methods of fabrication thereof

Abstract: A solid state radiation sensitive field emitter cathode comprising a single crystal semiconductor member having a body portion with a uniform array of closely spaced and very sharp electron emitting projections from one surface in the form of needles or whisker like members. Electrons are emitted into vacuum when a planar-parallel positive anode is mounted in close proximity to the surface. The cathode is responsive to input radiation such as electrons or light directed onto the cathode in modifying the electron emission from the array of electron emitter projections. The method of manufacturing the cathode by providing a predetermined pattern or mosaic of islands of a material exhibiting a greater etch resistant property than the semiconductor material, on a wafer of a semiconductor material and then etching out between and beneath the islands to undercut to a point where the islands are supported by only a small whisker of the semiconductor material. Removal of the islands results in an electron emitter being exposed from beneath each island wherein carriers generated within the body portion and also carriers generated within the depletion regions of the tips diffuse to the electron emitter projections wherein establishment of a high electric field at the tips of the electron emitter projections results in electron emission primarily due to conduction band tunneling. The device provides about 106 emitting points of close proximity so as to effect photographic-like imaging.

Phosphor combination and method, particularly adapted for use with explosives, for providing a distinctive information label

Abstract: Phosphor-explosive material combination and method wherein a small amount of inorganic phosphor is mixed with explosive material to provide an indicia or label of information regarding the explosive, either before or after detonation of same. The phosphor can readily be located with an ultraviolet lamp even after the explosive has been detonated, and by correlating the phosphor emission spectra with data known about the explosive when it is manufactured, the explosive can be identified. Line-emitting phosphors are especially useful because of their distinctive emission characteristics, which provide a vast number of possible combinations of emission which are correlated against the data known about the explosive when it is manufactured. Preferably the phosphor is formed as a combination of finely divided "spotter" phosphor and finely divided "coding" material held together by a binder in the form of small conglomerates, in order to facilitate initial location and later identification of same. There exists a vast number of different combinations of distinctive fluorescent emission, and these can be combined to label any item for later identification.

An electron microscopy study of precipitation in Cu-Ti sideband alloys

Abstract: Electron transmission microscopy and diffraction have revealed directly the fine-scale precipitation processes and the mechanism of formation of the periodic microstructures which characterize the decomposition of Cu-Ti “sideband” alloys. The initial stages of decomposition involve the development of «100» compositional waves giving rise to the well-known sideband or satellite reflections along the «100» directions. This «wave-like» clustering producing a triaxially modulated structure involves the formation of two disordered phases; ordering does not accompany the initial clustering. Prolonged aging produces a periodic array of interpenetrating rods along the «100» directions of the matrix. During aging the periodic structures coarsen according to a t1/3 law. The experimental activation energy for the coarsening of the modulated structures is approximately 48 kcal/ mole. Maximum strength is associated with the formation of the transition phase β’ which forms byin situ transformation of the titanium-rich regions; this transformation is not accompanied by a loss of coherency in the modulated structures at the aging temperatures studied in this investigation. It is suggested that these periodic structures arise from spinodal decomposition.

The diffusivity and solubility of oxygen in liquid copper and liquid silver from electrochemical measurements

Abstract: IN r ecen t y e a r s galvanic ce l l s i nco rpo ra t i ng sol id e l e c t r o l y t e s have been used to study the the rmodynamic and kinet ic behavior of oxygen in both l iquid and sol id m e t a l s . ~ The p r e s e n t work has u t i l ized such an e l e c t r o chemica l cel l of cy l ind r i ca l s y m m e t r y to de t e rmine the di f fus ivi ty and solubi l i ty of oxygen in mol ten pure copper and molten pure s i l v e r . Some prev ious t he rmodynamic s tudies on the mol ten Cu-O s y s t e m have been made using g a s m e t a l equi l i b r ium techniques . 2-6 Other au thors 6-16 have used e l e c t r o c h e m i c a l methods s i m i l a r to that employed he re . The p r i m a r y purpose of mos t of the p rev ious inves t iga t ions has been to de t e rmine the s tandard f r ee ene rgy of solution of oxygen in mol ten copper as a function of t e m p e r a t u r e . A compi la t ion of p rev ious s tudies is p r e sen t ed in Table I. F r o m previous de t e rmina t ions of the solubi l i ty of oxygen in l iquid s i l v e r , 17-19 the equ i l ib r ium solubi l i ty of oxygen in l iquid s i l v e r at 1 a tm p r e s s u r e is given as a function of t e m p e r a t u r e by the r e l a t ionsh ip

The Induction Range: Its Performance and Its Development Problems

Abstract: Both in its initial concept and in its present form, the induction range has many desirable features when compared to conventional ranges. These are readily demonstrable by its superior thermal response, its convenience, and safety. All these attributes are possible because the use of electromagnetic induction permits the pan to be heated directly without heating the range surface first.

Object identifying apparatus

Abstract: An object-identifying label having printed on a throw-away flexible substrate an identifying electrical circuit and moved with the object through a region where the identifying circuit is read. Typically, the object is a mail sack or baggage which is to be directed along a predetermined path. When the object moves through the region, the label is randomly positioned in the region. A substantially homogeneous electromagnetic field is produced in the region and as the object moves through the region, the circuit on the label is powered only by, and reacts with, the field, absorbing energy from the field.

Turbine rotor blade cooling and sealing system

Abstract: An assembly for sealing the root portions of gas turbine rotor blades of the side entry type into a rotor. The assembly also provides cooling for the blades. A radially directed three-sided channel disposed on the upstream side of the rotor near its periphery forces cooling fluid radially outward to a chamber beneath each blade root. The rotor, when rotating, causes the channel to act as a pump due to centrifugal force imparted to the cooling fluid. The coolant fluid is forced out the channel and into the chamber, then the coolant fluid is discharged radially through the blade root. A chamber sealing plate prevents axial leakage of the coolant past the downstream side of the blade root. The chamber sealing plate is fitted into a groove on the periphery of the rotor radially inwardly of and near the downstream end of the blade root. The sealing plate is notched, and interlocks with a corresponding tab in the downstream base of the blade root, which prevents the seal plates from moving circumferentially during turbine operation. The seal plate is further restrained axially by contact with an exhaust sealing and locking plate that is mounted in another peripheral groove downstream of the chamber sealing plate. The exhaust plate seals the downstream side of the blade entry channels, and locks the blades into the rotor.

In-Depth Compositional Profile Analysis of Alloys Using Optical Emission Glow Discharge Spectrography:

Abstract: Sequential analysis of metal alloys in depths of 0.1 to 40 μm are made with a glow discharge source for optical emission spectrography. The alloys examined have compositional variations in depth due to mass transfer in liquid sodium tests for materials studied in the fast breeder reactor program. The ion-sputtering action of the source produces progressive and discrete sampling of a defined area with concurrent excitation of the analytes in the negative glow region of the discharge. Integrated exposures of successive layers of attack are spectrographically recorded. The total weight loss is measured gravimetrically. Weight loss is assigned per exposure layer, and the depth of each attack is calculated. With more than 98% of the elemental composition measured, the sum of all elements is used as the internal standard. The precision approaches that of the photographic measurement process and does not indicate the ultimate precision of the source.

Blade shank cooling arrangement

Abstract: In a gas turbine engine, an arrangement for cooling turbine blade shanks for gas turbines, wherein a perforated chamber is arranged to cause a cooling fluid to impinge with a predetermined pattern upon inner wall surfaces of a cavity in a shank portion of a turbine blade and/or the outer walls of adjacent blade shanks. The cooling fluid may escape through radially directed passageways within the turbine blade or through a space between the adjacent blade platforms.

Cellular precipitation

Abstract: A theory of cellular precipitation is developed that assumes the interlamellar spacing to be controlled by the nucleation of new precipitate lamellae in recesses that develop in the advancing grain boundary at a sufficiently large interlamellar spacing. The theory also assumes a grain-boundary diffusion mechanism of mass transport, the maximum possible departure from local equilibrium across the grain boundary, and a grain-boundary model developed by Hillert. Application of the theory to all existing data that are sufficiently complet gives values for grain-boundary diffusivities that are both reasonable and in accord with existing diffusitivity data. It also suggests strongly that the velocity of grain-boundary migration is much more strongly dependent on driving force than the linear dependence given in most current theories. The interlamellar-spacing criterion proposed here is in reasonably good agreement with existing experimental data and with the experimental observation of Tu and Turnbull.

Absorption Coefficients for the Wings of the First Two Resonance Doublets of Cesium Broadened by Argon

Abstract: Measurements are reported of the absolute absorption coefficients in the wings of the 8944-, 8521-, 4593-, and 4555-\AA{} resonance lines of cesium in the presence of argon at densities between about 6 \ifmmode\times\else\texttimes\fi{} ${10}^{18}$ and 2 \ifmmode\times\else\texttimes\fi{} ${10}^{19}$ atom ${\mathrm{cm}}^{\ensuremath{-}3}$. The data extend from about 0.7 \AA{} to as much as 600 \AA{} from the line center and were obtained using cesium densities between 7 \ifmmode\times\else\texttimes\fi{} ${10}^{11}$ and 2 \ifmmode\times\else\texttimes\fi{} ${10}^{15}$ atom ${\mathrm{cm}}^{\ensuremath{-}3}$ and temperatures between 390 and 470\ifmmode^\circ\else\textdegree\fi{}K. The measured absorption coefficients are proportional to the product of the cesium and argon densities as expected from line broadening produced by binary collisions between cesium and argon atoms. Using the quasistatic theory as a guide for interpretation, the line profiles for wings of the first resonance doublet show a transition from a wavelength dependence determined by long-range van der Waals forces to a dependence determined by the short-range internuclear potentials discussed by Hedges, Drummond, and Gallagher (HDG). The far-wing absorption profiles obtained in the present experiments are in good agreement with those calculated from the fluorescence data of HDG.

Cyclic Fatigue of Hot‐Pressed Si3N4

Abstract: The cyclic fatigue behavior of two grades of hot-pressed silicon nitride was investigated. Flat, cantilever-type specimens were tested at temperatures up to 1300°C, in air, where the load was applied by an eccentric driver rotating at 1800 rpm, with a zero mean stress. The lifetime of the lower purity material at temperatures up to 1200°C was controlled by a stress corrosion mechanism. Above 1200°, and for both grades of material, plastic deformation, probably by grain boundary sliding, was rate controlling.

Radio Transmission to and from Underground Coal Mines--Theory and Measurement

Abstract: Research involved in the development of a radio communication system for use in coal mine disasters is described. Theoretically predicted field strengths for surface to mine and mine to surface propagation are compared with measurements in coal mines in Colorado and Pennsylvania. It is concluded that surface-to-mine voice communication is practical using a horizontal wire antenna operating at audio frequencies, and that mine-to-surface interrupted CW signaling is practical using multiple-turn horizontal loop antennas. This research has resulted in an emergency through-the-earth communication system that is being evaluated by the U.S. Bureau of Mines for use in mine rescue operations.

Control system with adaptive process controllers especially adapted for electric power plant operation

Abstract: An electric power plant including a steam generator and a steam turbine is operated by a control system including a turbine control, a boiler control and a plant unit master; each of the aforementioned controls includes integrating or adaptive controllers responsive to error signals to effect a desired control and ramp generators to provide an output against which a control process may be tracked. The integrating controllers include an integrating circuit for integrating an input error signal and a proportional circuit responsive to the error signal for providing an output signal to be summed with the output of the integrating circuit. The constant of the proportional circuit and the time constant of the integrating circuit are changed as a function of an index. In a control for an electric power plant, the index is the load reference provided by the plant unit master. A ramp generator is suggested that is capable of generating linear ramps at a fixed rate toward a known value, e.g. the control reference to be entered, and includes an integrating circuit to which is selectively applied first and second reference signals dependent upon whether the input signal is above or below a predetermined level.

Ferroelectric memory device

Abstract: A ferroelectric memory device utilizing the remanent polarization of a thin, ferroelectric film to control the surface conductivity of a bulk semiconductor and perform the memory function. The structure of the device is similar to a conventional MIS field effect transistor with the exception that the gate insulating layer is replaced by a thin film of active ferroelectric material comprising a reversably polarizable dielectric exhibiting hysteresis.

Control system and method for limiting power demand of an industrial plant

Abstract: The invention relates in general to control of the consumption of energy derived by an industrial user from a power supply system (electrical, gas or like commodity), and more particularly to a control system for adjusting an industrial load system to limit the demand of power while respecting the constraints of the load system.