Showing papers by "Westinghouse Electric published in 1993"

Vector analysis and control of advanced static VAr compensators

Abstract: The advanced static Var compensator (now widely known as the static condenser or STATCON) uses a high power self-commutating inverter to draw reactive current from a transmission line. Two fundamentally different types of invertor can be used for this purpose, one providing control of output voltage magnitude and phase angle, and the other having only phase angle control. For each of these types, the governing equations are derived, and frequency domain analysis is used to obtain the relevant transfer functions for control system synthesis. Further analysis is provided to determine the response of the STATCON to negative sequence and harmonic voltage components on the transmission line. The results are illustrated with measured waveforms obtained from a scaled analogue model of an 80 MVAr STATCON.< >

Waveguide filters having a layered dielectric structure

Abstract: Waveguide filters having a laminated dielectric structure for resonating at a predetermined frequency and having a series of longitudinally spaced resonators. A selected plural number of individual layers of high dielectric low temperature co-fired ceramic are laminated into a monolithic structure and then plated with a conductive material. Each of the individual layers is dimensioned and the number of layers is selected so that the unit resonates at the predetermined frequency. A waveguide filter is also described where a select plural number of contiguous layers of low temperature co-fired ceramic are laminated and plated with a conductive material. A series of vertically placed vias are positioned so as to form a perimeter of a waveguide filter. A plurality of individual layers of low temperature co-fired ceramic are laminated to the monolithic structure to form a laminated unit so that electrical components and the waveguide filter can be integrated into a single package.

Solid-state distribution current limiter and circuit breaker: application requirements and control strategies

Abstract: The design and application requirements for solid state distribution current limiters and circuit breakers are described and compared to those for the electromechanical switchgear used in present day distribution systems. Control strategies are provided for current limiting application in the power transformer main circuit and for current limiting and interruption for the bus tie location. >

Railway signalling system

Abstract: A railway signalling system comprising a control device for controlling the movements of railway vehicles on a railway track. The system includes a memory for storing data defining physical characteristics of the railway track and the locations of the vehicles, a first processor for processing the data stored in the memory to determine permissible movements of the vehicles, and a first interface for transmitting to the vehicles movement data defining the vehicles' permissible movements; and a protection unit carried by at least one of the vehicles for causing the vehicle to move under the control of the control device, comprising a second interface receiving the movement data relating to the vehicle, a second memory for storing geographical data defining physical characteristics of the railway track, a second processor for processing the movement data in dependence on the geographical data to determine an operating speed for the vehicle, and an operation unit for controlling the travel of the vehicle at the determined operating speed.

Gas turbine combustor swirl vane arrangement

Abstract: A combustor for a gas turbine having a centrally located fuel nozzle and inner, middle and outer concentric cylindrical liners, the inner liner enclosing a primary combustion zone. The combustor has an air inlet that forms two passages, each of which has a circumferential array of individually rotatable swirl vanes. The swirl vanes are mounted on axially oriented primary fuel pegs that extend through the air inlet passages. The middle and outer liners form an outer annular passage in which radially oriented secondary fuel pegs are disposed. The middle and inner liners form an inner annular passage that is supplied with cooling air. A perforated circumferentially extending baffle is locating in the inner annular passage and directs the cooling air to flow over the inner liner.

Regulating a railway vehicle

Abstract: Apparatus for use in a railway vehicle for regulating it, comprising: means for calculating running profiles between two or more fixed destinations; means for receiving, either from a second or subsequent railway vehicle, directly or via separate means, the time at which one or more of the destinations will become clear for use by the railway vehicle; means for knowing what balance to apply to trade-offs between two or more operational strategies; means for knowing the timetabled arrival and departure times scheduled for it at any destination; and means for reporting to any second or subsequent railway vehicle, either directly or via separate means, its calculated arrival time at any destination.

Non-volatile random access memory cell constructed of silicon carbide

Abstract: A non-volatile random access memory (NVRAM) cell that utilizes a simple, single-transistor DRAM cell configuration. The present NVRAM employs an enhancement mode nMOS transistor made as an accumulation mode transistor. The transistor has an n-type silicon carbide channel layer on a p-type silicon carbide buffer layer, with the channel and buffer layers being on a highly resistive silicon carbide substrate. The transistor also has n+ source and drain contact regions on the channel layer. A polysilicon/oxide/metal capacitor is preferably used which has a very low leakage current. Furthermore, this type of capacitor can be stacked on top of the transistor to save area and achieve high cell density. It is preferred to use a non-reentrant (edgeless) gate transistor structure to further reduce edge effects.

Deterministic, probabilistic and subjective modeling system

Abstract: A modeling system that arranges the model in a hierarchical structure of communicating and independently executing object modules controlled by an overall supervisor. Each object represents a component or a system and includes an object controller which communicates with other object modules, an object error checker and an object model. The objects communicate through a database accessible by all objects. The structure of the object module and the hierarchical structure itself are standardized allowing new components or systems to be added by adding a standard object module which includes an object model that is unique to the object being modeled. The controller for an object causes subobjects upon which the object model depends for data to be executed prior to execution of the object model. Such bottom up model traversal insures that models do not execute until all needed data is available. The error check module checks the controller and model modules to make sure they are executing properly. The object model includes a deterministic equation based component aging model, a statistical based component aging model and expert rules that combine the deterministic and statistical model with the knowledge of experts to determine the current state of the object and make recommendations concerning future actions concerning the object. A maintenance module is also included along side the supervisor that allows maintenance actions for the objects to be taken into consideration.

Effect of Humidity and Particle Hygroscopicity on the Mass Loading Capacity of High Efficiency Particulate Air (HEPA) Filters

Abstract: The effect of humidity, particle hygroscopicity, and size on the mass loading capacity of glass fiber high efficiency particulate air filters was studied. Above the deliquescent point, the pressure drop across the filter increased nonlinearly with areal loading density (mass collected/filtration area) of a NaCl aerosol, thus significantly reducing the mass loading capacity of the filter compared to dry hygroscopic or nonhygroscopic particle mass loadings. The specific cake resistance K 2 was computed for different test conditions and used as a measure of the mass loading capacity. K 2 was found to decrease with increasing humidity for nonhygroscopic aluminum oxide particles and for hygroscopic NaCl particles (at humidities below the deliquescent point). It is postulated that an increase in humidity leads to the formation of a more open particulate cake which lowers the pressure drop for a given mass loading. A formula for predicting K 2 for lognormally distributed aerosols (parameters obtained from impact...

Durra: a structure description language for developing distributed applications

Abstract: Durra is a language and runtime support system for developing distributed applications. In this paper, we describe the general nature of these applications, and the need for separating structural and behavioural details. A Durra user describes an application as a set of components (application tasks and communication channels), a set of alternative configurations showing how these components are connected at runtime, and a set of conditional configuration transitions that take place at runtime. We illustrate these features through examples drawn from the fault tolerance domain. We conclude with an illustration of the use of Durra in an incremental software development scenario.

Effect of an axial magnetic field upon the development of the vacuum arc between opening electric currents (currents read contacts)

Abstract: In one series of experiments, a constant axial magnetic field B/sub ax/ was produced in the gap between opening Bruce-profile, chromium-copper contacts. Peak arc currents up to 40 kA at 50 Hz were studied with B/sub ax/ u to 112 mT. For each peak current, a critical field B/sub crit/ was determined above which anode spots did not form. For B/sub ax/ greater than B/sub crit/, the time from contact parting to the formation of a diffuse vacuum arc was linearly dependent on separation current. In a second series, the contacts were designed to generate a self B/sub ax/ when AC current up to 123 kA peak flowed. This field was approximately proportional to the current waveform through the contacts, and it was always higher than the B/sub crit/ predicted for the instantaneous current. The time from contact parting to the formation of the diffuse arc was consistent with that observed in the first experimental series. Once the diffuse arc had formed, the contacts showed no distributed melting for currents up to 81 kA, but gross melting occurred at 102-123 kA. The formation of diffuse arcs is discussed, and the anode melting is explained. >

The effect of porosity on the microstructural damping response of 6061 aluminium alloy

Abstract: The paper reports on the results of a systematic study of the effects of micrometre-sized pores on the damping response of 6061 aluminium alloy. Spray atomization and deposition processing was utilized for the present study as a result of its ability to produce a material with a pre-determined amount of non-interconnected, micrometre-sized pores. The amount and distribution of pores present in the material may be systematically altered through variations in the processing parameters by using this synthesis approach. The damping measurements were conducted on cantilever beam specimens by using free vibration decay and resonant vibration techniques. Experimental results showed that the porosity increased with increasing average pore size; the damping capacity, in terms of logarithmic decrement δ, of the as-spray-deposited 6061 Al alloy, increased from 1.8 to 2.9% as the amount of porosity increased from 4 to 10%. Comparisons show that the damping capacity of the as-spray-deposited 6061 Al alloy is higher than those reported by other investigators using the same alloy but with different processing techniques. The loading damping mechanisms are discussed in the light of data from the characterization of microstructure and damping capacity.

Separation of spiral contacts and the motion of vacuum arcs at high AC currents

Abstract: A framing camera is used to photograph the vacuum arc between separating spiral-petal vacuum interrupter contacts. The rupture of the molten bridge between the contacts first leads to a high-pressure, transient arc column. This arc motion can become constricted for several milliseconds before it goes diffuse as the current decreases to zero. The current through the spiral contacts produces a magnetic field perpendicular to the arc column, which forces the arc to move outward and run along the periphery of the petals. Several vacuum arc modes occur during the half-cycle of high current arcing. Movies, gap-current curves, and arc voltage traces are used to study the development of the arc motion and how it is affected by the contact structure. This information is used to generate arc appearance diagrams in which the arc form and motion are correlated to instantaneous values of current and gap for a wide range of peak currents. Appearance diagrams are shown for two ranges of opening delay from current onset. >

Gas turbine dual fuel nozzle assembly with steam injection capability

Abstract: A fuel nozzle assembly is provided having the capability of burning either gaseous or liquid fuel, or both simultaneously, along with steam injection. The nozzle has a nozzle body that is attached to a nozzle cap by inner, outer and middle sleeves. The sleeves form inner and outer concentric annular conduits between themselves for directing the flow of gaseous fuel and steam from the fuel and steam inlet ports to the outlet ports. In addition, the inner sleeve forms a central chamber in which an oil fuel nozzle is disposed. Radial passages in the nozzle body allow cooling air to flow over the oil nozzle and through the oil outlet port, thereby preventing coking at the nozzle tip. The fuel nozzle assembly is originally built, and the nozzle cap is replaced, by sliding the sleeves forward and aft on the assembly so as to gain access to the next innermost sleeve.

Gas turbine vane

Abstract: A vane for the turbine section of a gas turbine has an airfoil portion with leading edge, center and trailing edge portions. The leading edge portion is attached to the center portion by a dove tail joint that allows the leading edge portion to slide in the radial direction with respect to the center portion while preventing movement in the axial and circumferential directions, thereby eliminating thermal stresses created by differential thermal expansion between the leading edge portion and the remainder of the vane. An opening in the vane inner shroud that is normally sealed by a closure plate allows the leading edge portion to be readily replaced in the event of damage. The leading edge portion may be formed from a ceramic material and need not be supplied with cooling air.

Tritium transport and cycling in the environment.

Abstract: The transport and cycling of tritium in the environment can be understood in terms of the role of hydrogen in the environment. Physical and chemical isotopic effects, while present in some transport mechanisms and chemical reactions, are not important factors in environmental tritium dynamics. In addition, because of the role of hydrogen in metabolism and its ubiquitousness in the environment, organisms have not evolved mechanisms to accumulate or concentrate hydrogen or its isotopes in food chains. Therefore, biomagnification of tritium is not a factor in food chain transfer. The lack of significant isotopic effects or biomagnification means that tritium transport and cycling in the environment can be predicted on the basis of the transport processes, hydrogen content, and chemical transformation of hydrogen and its compounds in the environment.

Frequency selective limiters for high dynamic range microwave receivers

Abstract: A broadband frequency selective limiter (FSL) which provides over 14 dB of limiting across more than an octave bandwidth is described The limiter is fabricated with epitaxially grown YIG (yttrium iron garnet) films in a stripline configuration and has a threshold power level of below 0 dBm Individual limiter strips limit microwave signals in the 1-100-mW range across more than an octave of bandwidth Multiple FSLs have been cascaded with amplifiers to allow compression of microwave signals with a power range of 60 dB into a range of less than 5 dB >

Concerning the formation of hydrogen in nuclear waste. Quantitative generation of hydrogen via a Cannizzaro intermediate

Abstract: During the storage of certain nuclear waste, particularly mixtures containing complexing agents like EDTA and HEDTA in highly basic media, mixtures of gases containing large amounts of hydrogen are produced. In order to provide the foundation for control of this potentially dangerous situation, a fundamental understanding of the reactions responsible for the formation of hydrogen is crucial. The proposed mechanism for the formation of H[sub 2] involves the formation of a Cannizzaro intermediate, which reacts as a hydride ion donor with a water molecule, to produce hydrogen and sodium formate. Conditions are believed to be presented in nuclear waste storage tanks where small, steady-state concentrations of formaldehyde can form by radiolysis or thermal decomposition of organic complexants and other decomposition products. Formaldehyde and other aldehydes that do not possess [alpha] hydrogen atoms are very likely intermediates for the generation of H[sub 2] during the storage of alkaline nuclear waste. The data reported herein suggests that formaldehyde and water each provide one hydrogen atom in the formation of H[sub 2]. 12 refs., 4 tabs.

Pressure-composition isotherms for palladium hydride.

Abstract: We present Monte Carlo calculations of the pressure-composition isotherms of palladium hydride using recently constructed embedded-atom-method potentials and a Monte Carlo method that allows for volume equilibration as the composition varies.

Infrared properties of epitaxial La2-xSrxCuO4 thin films in the normal and superconducting states.

Abstract: The ${\mathrm{CuO}}_{2}$-plane optical reflectance of superconducting ${\mathrm{La}}_{2\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{Sr}}_{\mathit{x}}$${\mathrm{CuO}}_{4}$ thin films (${\mathit{T}}_{\mathit{c}}$\ensuremath{\simeq}31 K) has been measured over a wide frequency and temperature range. The optical conductivity in the normal state is well described by a temperature-dependent weak-coupling (\ensuremath{\lambda}\ensuremath{\approxeq}0.25) free-carrier term plus an overdamped, weakly temperature-dependent, midinfrared component. The free-carrier plasma frequency is nearly constant, ${\mathrm{\ensuremath{\omega}}}_{\mathit{p}\mathit{D}}$=6300 ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$, whereas the relaxation rate varies linearly with temperature above ${\mathit{T}}_{\mathit{c}}$. In the superconducting state, according to our two-component approach, most of the Drude oscillator strength condenses to a \ensuremath{\delta}(\ensuremath{\omega}) function. A two-fluid analysis gives a rapid drop in the quasiparticle damping rate below ${\mathit{T}}_{\mathit{c}}$. A reasonable estimate (\ensuremath{\sim}2750 \AA{}) for the ab-plane London penetration depth is obtained from the superfluid density. We observe that the midinfrared strength increases below ${\mathit{T}}_{\mathit{c}}$, suggesting that some (\ensuremath{\sim}15%) of the free carriers do not condense into superconducting pairs and may have a strong interaction with pair-breaking excitations. Two absorption edges around 80 ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$ (3.7 ${\mathit{k}}_{\mathit{B}}$${\mathit{T}}_{\mathit{c}}$) and 400 ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$ (18 ${\mathit{k}}_{\mathit{B}}$${\mathit{T}}_{\mathit{c}}$) are seen but neither is assigned to the superconducting gap. Comparisons with a one-component picture described by a frequency-dependent scattering rate and effective mass are made and discussed. The far-infrared ab-plane phonons show systematic changes with temperature, which are associated with the structural transition near 250 K.

MICROX-an all-silicon technology for monolithic microwave integrated circuits

Abstract: An improved silicon-on-insulator (SOI) approach offers devices and circuits operating to 10 GHz by providing formerly unattainable capabilities in bulk silicon: reduced junction-to-substrate capacitances in FETs and bipolar transistors, inherent electrical isolation between devices, and low-loss microstrip lines. The concept, called MICROX (patent pending), is based on the SIMOX process, but uses very-high-resistivity (typically>10000 Omega -cm) silicon substrates, MICROX NMOS transistors of effective gate length 0.25 mu m give a maximum frequency of operation, f/sub max/, of 32 GHz and f/sub T/ of 23.6 GHz in large-periphery (4 mu m*50 mu m) devices with no correction for the parasitic effects of the pads. The measured minimum noise figure is 1.5 dB at 2 GHz with associated gain of 17.5 dB, an improvement over previously reported values for silicon FETs. >

Non-contact two position microeletronic cantilever switch

Abstract: A microelectrostatic cantilever switch that has a thin impermeable oxide layer on the surface of a contact pad which is engaged by an unsupported portion of a cantilever beam when the switch is in a closed position. The switch in the open position exhibits a capacitance between the cantilever beam and contact pad of 0.8 Pf and a capacitance of 0.001 to 0.01 Pf in the closed position.

Thermoplastic and thermoset main chain liquid crystal polymers prepared from biphenyl mesogen

Abstract: Main chain liquid crystal thermoplastic polyesters and thermosetting epoxy resins were prepared using biphenyl mesogens. The melting points of the polyesters were effectively decreased by incorporating flexible methylene spacers into the polymer main chain. The liquid crystal epoxy resins exhibit high glass transition temperature, low thermal expansion coefficients, high dielectric strengths, and low dielectric loss. They are suitable for the preparation of self-reinforcing molecular composites. © 1993 John Wiley & Sons, Inc.

Automotive navigation system and method

Abstract: A navigation system for a vehicle travelling along a highway that has an interrogator mounted on the vehicle and, a retrodirective transponder mounted alongside the highway for updating vehicle location. For collision avoidance systems, interrogators transmit and receive fore and aft, and transponders are mounted to respond to signals fore and aft of the vehicle. The transponder modulates information onto the interrogation signal, and retransmits the encoded interrogation signal back in the direction of arrival of the collected interrogation signal. The responder uses a Van Atta array antenna and is capable of responding to an interrogator signal incident over a wide solid angle of arrival while retrodirectively retransmitting without amplification substantially all of the collected signal within a narrow solid angle. The responder may be implemented using monolithic microwave integrated circuit technology (MMIC), thus being suitable for high volume production.

Synchronization of Time clocks in a distributed processing network system

Abstract: A distributed processing system (1) comprising: a plurality of stations (3) each having a processor station (17) having an operating system having a station time of day clock and a network interface (15); a data communication network (5) connecting the plurality of stations (3) via the network interface (15); and Synchronization devices for synchronizing the station time of day clocks in the station processors; Means (23) within a predetermined timer station periodically generate a timer signal, which is sent via the data communication network (5) to all stations (3) including the timer station; wherein the synchronization devices are characterized by: a free-running counter (19) in each of the network interfaces that perform a counting of time intervals; Retention devices (21) in each of the network interfaces for storing the count value; Devices in each of the network interface (15), which hold the count value of the free running counter (19) in the retainer (21) upon receipt of the timing signal; Devices (39-45) in the timer station, then via the data communication network to all stations, a timer-day signal ...

Damping behavior of 6061Al/Gr metal matrix composites

Abstract: The damping behavior of graphite particulate-reinforced 6061A1 alloy metal matrix composites (MMCs) processed by spray atomization and codeposition is studied. Four spray deposition experiments are made, yielding materials with graphite volume fractions of 0, 0.05, 0.07, and 0.10. A dynamic mechanical thermal analyzer is used to measure the damping capacity and elastic modulus at 0.1, 1, and 10 Hz over the temperature range of 30 °C to 250 °C. The damping capacity of the materials is shown to increase with increasing volume fraction of graphite. Hot extrusion of the spray-deposited MMCs is shown to further increase the damping capacity. The elastic moduli of the spray-deposited MMCs are reduced with the addition of graphite but are improved by hot extrusion. At low temperatures (below 150 °C), the high damping capacity of the MMCs is attributed primarily to thermal expansion mismatch-induced dislocations and the high intrinsic damping of graphite. At high temperatures (above approximately 200 °C), the damping capacity is attributed to Al/graphite interface viscosity, preferred orientation of the graphite, and the presence of dislocations.

Exhaust system for a turbomachine

Abstract: An exhaust system for an axial flow turbomachine is provided having a diffuser that directs the flow of working fluid from a turbine exit to an exhaust housing having a bottom opening, thereby turning the flow 90° from the axial to radial direction In the exhaust housing, the flow exiting at the top of the diffuser turns 180° from the vertically upward direction to the downward direction The strength of the vortex formed in the exhaust housing as a result of this turning is minimized by orienting the outlet of an outer exhaust flow guide portion of the diffuser so that it lies in a plane that makes an angle with a plane perpendicular to the turbine axis As a result, the minimum axial length of the outer flow guide occurs at a location remote from the exhaust housing outlet and the maximum axial length occurs at a location proximate the opening, thereby crowding the vortex against a radially extending baffle in the exhaust housing

Josephson sigma-delta modulator for high dynamic range A/D conversion

Abstract: A Josephson sigma-delta modulator suitable for use in high dynamic range conversion of MHz bandwidth signals was designed and simulated. Input signal voltages were integrated as current in a superconducting inductor. A single junction quantizer provided analog-to-digital (AID) conversion at 40 GHz and fed back single-flux-quantum (SFQ) voltage pulses to balance the input. A JSIM calculation for a 13,110,000-ps interval indicated ideal first-order noise shaping of a 2.44-MHz voltage-source signal. Spur free dynamic range was 102 dB and signal-to-noise-and-distortion was 98 dB on the DC 10-MHz signal band, equivalent to a 16-b, 20-MSample/s, Nyquist-rate A/D. The modulator transfer function was derived for a current-source signal applied to an input resistor. First-order quantization noise suppression was still observed for signal bands wider than the 2 pi R/L modulator cutoff frequency. The superconductive sigma-delta modulator combines the speed of Josephson junctions for GHz sampling and digital filtering with the quantum mechanical accuracy of SFQ feedback to obtain superior A/D performance. >