Science.gov

Sample records for flying capacitor multilevel

  1. Wide-range 7-switch flying capacitor based dc-dc converter for point-of-load applications

    NASA Astrophysics Data System (ADS)

    Jain, Parth

    In this thesis a dc-dc converter referred to as the 7-switch flying capacitor (7SFC) based multi-level buck converter intended for point-of-load applications is presented. The 7SFC operates with the principle of "transformability" which allows it to run in several switching modes when paired with a digital controller. The mode is selected based on input and output conditions by estimating the highest efficiency mode. The 7SFC converter utilizes a flying capacitor, which for certain modes allows for a large reduction in switching losses, especially when the converter is operated with high-input voltages. Compared to the conventional 2-phase interleaved buck converter, the 7SFC is able to reduce the size of the output inductors and capacitor by 33%. The 7SFC discrete prototype is able to achieve efficiencies greater than 90% over the majority of the operating range.

  2. New zero voltage switching DC converter with flying capacitors

    NASA Astrophysics Data System (ADS)

    Lin, Bor-Ren; Shiau, Tung-Yuan

    2016-04-01

    A new soft switching converter is presented for medium power applications. Two full-bridge converters are connected in series at high voltage side in order to limit the voltage stress of power switches at Vin/2. Therefore, power metal-oxide-semiconductor field-effect transistors (MOSFETs) with 600 V voltage rating can be adopted for 1200 V input voltage applications. In order to balance two input split capacitor voltages in every switching cycle, two flying capacitors are connected on the AC side of two full-bridge converters. Phase-shift pulse-width modulation (PS-PWM) is adopted to regulate the output voltage. Based on the resonant behaviour by the output capacitance of MOSFETs and the resonant inductance, active MOSFETs can be turned on under zero voltage switching (ZVS) during the transition interval. Thus, the switching losses of power MOSFETs are reduced. Two full-bridge converters are used in the proposed circuit to share load current and reduce the current stress of passive and active components. The circuit analysis and design example of the prototype circuit are provided in detail and the performance of the proposed converter is verified by the experiments.

  3. Capacitors.

    ERIC Educational Resources Information Center

    Trotter, Donald M., Jr.

    1988-01-01

    Presents a historical backdrop for a discussion of capacitor design and function. Discusses the production, importance, and function of two types of miniature capacitors; electrolytic and multilayer ceramic capacitors. Describes the function of these miniature capacitors in comparison to the Leyden jar, a basic demonstration of capacitance. (CW)

  4. Switched-capacitor isolated LED driver

    DOEpatents

    Sanders, Seth R.; Kline, Mitchell

    2016-03-22

    A switched-capacitor voltage converter which is particularly well-suited for receiving a line voltage from which to drive current through a series of light emitting diodes (LEDs). Input voltage is rectified in a multi-level rectifier network having switched capacitors in an ascending-bank configuration for passing voltages in uniform steps between zero volts up to full received voltage V.sub.DC. A regulator section, operating on V.sub.DC, comprises switched-capacitor stages of H-bridge switching and flying capacitors. A current controlled oscillator drives the states of the switched-capacitor stages and changes its frequency to maintain a constant current to the load. Embodiments are described for isolating the load from the mains, utilizing an LC tank circuit or a multi-primary-winding transformer.

  5. Multi-Level Determinants of Parasitic Fly Infection in Forest Passerines

    PubMed Central

    Manzoli, Darío Ezequiel; Antoniazzi, Leandro Raúl; Saravia, María José; Silvestri, Leonardo; Rorhmann, David; Beldomenico, Pablo Martín

    2013-01-01

    The study of myiasis is important because they may cause problems to the livestock industry, public health, or wildlife conservation. The ecology of parasitic dipterans that cause myiasis is singular, as they actively seek their hosts over relatively long distances. However, studies that address the determinants of myiasis dynamics are very scarce. The genus Philornis include species that may be excellent models to study myiasis ecology, as they exclusively parasitize bird nestlings, which stay in their nests until they are fully fledged, and larvae remain at the point of entry until the parasitic stage is over, thus allowing the collection of sequential individual-level infection data from virtually all the hosts present at a particular area. Here we offer a stratified multi-level analysis of longitudinal data of Philornis torquans parasitism in replicated forest bird communities of central Argentina. Using Generalized Linear Models and Generalized Linear Mixed Models and an information theory approach for model selection, we conducted four groups of analyses, each with a different study unit, the individual, the brood, the community at a given week, and the community at a given year. The response variable was larval abundance per nestling or mean abundance per nestling. At each level, models included the variables of interest of that particular level, and also potential confounders and effect modifiers of higher levels. We found associations of large magnitude at all levels, but only few variables truly governed the dynamics of this parasite. At the individual level, the infection was determined by the species and the age of the host. The main driver of parasite abundance at the microhabitat level was the average height of the forest, and at the community level, the density of hosts and prior rainfall. This multi-level approach contributed to a better understanding of the ecology of myiasis. PMID:23874408

  6. FLIES

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Flies constitute a major group of nuisance species world wide in rural and urban situations. The public and health care officials can become more aware of the potential risks from flies and other urban pests by compiling the available information into an easily readable book form. Scientists from ...

  7. A multilevel voltage-source inverter with separate dc sources for static var generation

    SciTech Connect

    Peng, Fang Zheng |; Lai, Jih-Sheng; McKeever, J.; VanCoevering, J.

    1995-09-01

    A new multilevel voltage-source inverter with a separate dc sources is proposed for high-voltage, high-power applications, such as flexible ac transmission systems (FACTS) including static var generation (SVG), power line conditioning, series compensation, phase shifting, voltage balancing, fuel cell and photovoltaic utility systems interfacing, etc. The new M-level inverter consists of (M-1)/2 single phase full bridges in which each bridge has its own separate dc source. This inverter can generate almost sinusoidal waveform voltage with only one time switching per cycle as the number of levels increases. It can solve the problems of conventional transformer-based multipulse inverters and the problems of the multilevel diode-clamped inverter and the multilevel flying capacitor inverter. To demonstrate the superiority of the new inverter, a SVG system using the new inverter topology is discussed through analysis, simulation and experiment.

  8. A Multi-Level Grid Interactive Bi-directional AC/DC-DC/AC Converter and a Hybrid Battery/Ultra-capacitor Energy Storage System with Integrated Magnetics for Plug-in Hybrid Electric Vehicles

    SciTech Connect

    Onar, Omer C

    2011-01-01

    This study presents a bi-directional multi-level power electronic interface for the grid interactions of plug-in hybrid electric vehicles (PHEVs) as well as a novel bi-directional power electronic converter for the combined operation of battery/ultracapacitor hybrid energy storage systems (ESS). The grid interface converter enables beneficial vehicle-to-grid (V2G) interactions in a high power quality and grid friendly manner; i.e, the grid interface converter ensures that all power delivered to/from grid has unity power factor and almost zero current harmonics. The power electronic converter that provides the combined operation of battery/ultra-capacitor system reduces the size and cost of the conventional ESS hybridization topologies while reducing the stress on the battery, prolonging the battery lifetime, and increasing the overall vehicle performance and efficiency. The combination of hybrid ESS is provided through an integrated magnetic structure that reduces the size and cost of the inductors of the ESS converters. Simulation and experimental results are included as prove of the concept presenting the different operation modes of the proposed converters.

  9. Advanced capacitors

    NASA Astrophysics Data System (ADS)

    Ennis, J. B.; Buritz, R. S.

    1984-10-01

    This report describes an experimental program to develop and test advanced dielectric materials for capacitors for airborne power systems. Five classes of capacitors were considered: high rep rate and low rep rate pulse capacitors for use in pulse-forming networks, high voltage filter capacitors, high frequency AC capacitors for series resonant inverters, and AC filter capacitors. To meet these requirements, existing dielectric materials were modified, and new materials were developed. The initial goal was to develop an improved polysulfone film with fewer imperfections that could operate at significantly higher electrical stresses. It was shown that contaminants enter the film via the resin and solvent, and that they can be partially removed. As far as developed, however, these treatments did not significantly improved the breakdown characteristics. The technique of casting films on a roughened drum was demonstrated, and found useful in preparing textured films -- the first step toward a replacement for Kraft paper. A new material, Ultem, was proposed for use in high energy density capacitors. This new polyetherimide resin has properties similar to polysulfone and polyimide, with improvement in breakdown characteristics and temperature capability. This material was selected for further study in model capacitor designs.

  10. Vented Capacitor

    DOEpatents

    Brubaker, Michael Allen; Hosking, Terry Alan

    2006-04-11

    A technique of increasing the corona inception voltage (CIV), and thereby increasing the operating voltage, of film/foil capacitors is described. Intentional venting of the capacitor encapsulation improves the corona inception voltage by allowing internal voids to equilibrate with the ambient environment.

  11. MOCVD capacitors

    SciTech Connect

    Lanagan, M.T.; Foster, C.

    1997-09-01

    A significant effort within the Department of Energy`s Office of Transportation Technologies and the U.S. Navy`s Power Electronic Building Block (PEBB) project has focused on reducing the size and weight of power electronic devices for electric and hybrid vehicles. Power electronic circuits, which are composed of active switching elements and passive components such as capacitors and inductors, provide motor control, power distribution, and DC/AC conversion functions in electric vehicles. Progress has been made on reducing the size and weight of power electronic components such as MOS-controlled thristors and insulated-gate bipolar transistors. Additional effort on high-power capacitors will be needed for load leveling and filter functions. The objective of this work is to fabricate a new class of high-power capacitors with reduced size and weight. Capacitors will be integrated with semiconductor components of electric motor and actuator control subsystems.

  12. Advanced capacitors

    NASA Astrophysics Data System (ADS)

    Parker, R. D.; Buritz, R. S.; Taylor, A. R.; Bullwinkel, E. P.

    1982-11-01

    An experimental development program was conducted to develop and test advanced dielectric materials for capacitors for airborne power systems. High rep rate and low rate capacitors for use in pulse-forming networks, high voltage filter capacitors, and high frequency ac capacitors for series resonant inverters were considered. The initial goal was to develop an improved polysulfone film. Initially, low breakdown strength was thought to be related to inclusions of conductive particles. The effect of filtration of the casting solution was investigated. These experiments showed that more filtration was not the entire solution to low breakdown. The film samples were found to contain dissolved ionic impurities that move through the dielectric when voltage is applied and cause enhancement of the electric field. These contaminants enter the film via the resin and solvent, and can be partially removed. However, these treatments did not significantly improve the breakdown characteristics. A new material, Ultem, was proposed for use in high energy density capacitors. This new polyetherimide resin has properties similar to polysulfone and polyimide, with improvement in breakdown characteristics and temperature capability. The technique of casting films on a roughened drum was demonstrated, and found useful in preparing textured films. this is the first step toward a replacement for kraft paper.

  13. Electrochemical capacitor

    DOEpatents

    Anderson, Marc A.; Liu, Kuo -Chuan; Mohr, Charles M.

    1999-10-05

    An inexpensive porous metal oxide material having high surface area, good conductivity and high specific capacitance is advantageously used in an electrochemical capacitor. The materials are formed in a sol-gel process which affords control over the properties of the resultant metal oxide materials.

  14. Mechanical capacitor

    NASA Technical Reports Server (NTRS)

    Kirk, J. A.; Studer, P. A.; Evans, H. E.

    1976-01-01

    A new energy storage system (the mechanical capacitor), using a spokeless magnetically levitated composite ring rotor, is described and design formulas for sizing the components are presented. This new system is configured around a permanent magnet (flux biased) suspension which has active servo control in the radial direction and passive control in the axial direction. The storage ring is used as a moving rotor and electronic commutation of the stationary armature coils is proposed. There is no mechanical contact with the rotating spokeless ring; therefore, long life and near zero rundown losses are projected. A 7-kW h system is sized to demonstrate feasibility. A literature review of flywheel energy storage systems is also presented and general formulas are developed for comparing rotor geometries.

  15. Practical Active Capacitor Filter

    NASA Technical Reports Server (NTRS)

    Shuler, Robert L., Jr. (Inventor)

    2005-01-01

    A method and apparatus is described that filters an electrical signal. The filtering uses a capacitor multiplier circuit where the capacitor multiplier circuit uses at least one amplifier circuit and at least one capacitor. A filtered electrical signal results from a direct connection from an output of the at least one amplifier circuit.

  16. High Energy Density Capacitors

    SciTech Connect

    2010-07-01

    BEEST Project: Recapping is developing a capacitor that could rival the energy storage potential and price of today’s best EV batteries. When power is needed, the capacitor rapidly releases its stored energy, similar to lightning being discharged from a cloud. Capacitors are an ideal substitute for batteries if their energy storage capacity can be improved. Recapping is addressing storage capacity by experimenting with the material that separates the positive and negative electrodes of its capacitors. These separators could significantly improve the energy density of electrochemical devices.

  17. Variable-speed wind power system with improved energy capture via multilevel conversion

    DOEpatents

    Erickson, Robert W.; Al-Naseem, Osama A.; Fingersh, Lee Jay

    2005-05-31

    A system and method for efficiently capturing electrical energy from a variable-speed generator are disclosed. The system includes a matrix converter using full-bridge, multilevel switch cells, in which semiconductor devices are clamped to a known constant DC voltage of a capacitor. The multilevel matrix converter is capable of generating multilevel voltage wave waveform of arbitrary magnitude and frequencies. The matrix converter can be controlled by using space vector modulation.

  18. Nonelectrolytic tantalum capacitors developed

    NASA Technical Reports Server (NTRS)

    1966-01-01

    Large area, nonelectrolytic tantalum foil capacitor has capacitance of approximately 1 microfarad and is capable of operating at 125 deg C at 150 volts with an insulation resistance of at least 1 megohm. In tests at a potential of 100 volts, capacitors remained stable through a temperature range from 25 deg to 125 deg C.

  19. High Temperature Capacitor Development

    SciTech Connect

    John Kosek

    2009-06-30

    The absence of high-temperature electronics is an obstacle to the development of untapped energy resources (deep oil, gas and geothermal). US natural gas consumption is projected to grow from 22 trillion cubic feet per year (tcf) in 1999 to 34 tcf in 2020. Cumulatively this is 607 tcf of consumption by 2020, while recoverable reserves using current technology are 177 tcf. A significant portion of this shortfall may be met by tapping deep gas reservoirs. Tapping these reservoirs represents a significant technical challenge. At these depths, temperatures and pressures are very high and may require penetrating very hard rock. Logistics of supporting 6.1 km (20,000 ft) drill strings and the drilling processes are complex and expensive. At these depths up to 50% of the total drilling cost may be in the last 10% of the well depth. Thus, as wells go deeper it is increasingly important that drillers are able to monitor conditions down-hole such as temperature, pressure, heading, etc. Commercial off-the-shelf electronics are not specified to meet these operating conditions. This is due to problems associated with all aspects of the electronics including the resistors and capacitors. With respect to capacitors, increasing temperature often significantly changes capacitance because of the strong temperature dependence of the dielectric constant. Higher temperatures also affect the equivalent series resistance (ESR). High-temperature capacitors usually have low capacitance values because of these dielectric effects and because packages are kept small to prevent mechanical breakage caused by thermal stresses. Electrolytic capacitors do not operate at temperatures above 150oC due to dielectric breakdown. The development of high-temperature capacitors to be used in a high-pressure high-temperature (HPHT) drilling environment was investigated. These capacitors were based on a previously developed high-voltage hybridized capacitor developed at Giner, Inc. in conjunction with a

  20. Electrochemical flow capacitors

    DOEpatents

    Gogotsi, Yury; Presser, Volker; Kumbur, Emin Caglan

    2015-10-27

    The present invention generally relates to devices for energy storage technologies, and more particularly to electrochemical flow capacitor systems and applications. In some aspects, these flow capacitors have at least one electrode comprising a non-stationary solid or semi-solid composition comprising supercapacitive particles and an electrolytic solvent in electrical communication with at least one current collector, and energy is stored and/or released by charging and/or discharging the electrode(s).

  1. Materials for electrochemical capacitors.

    PubMed

    Simon, Patrice; Gogotsi, Yury

    2008-11-01

    Electrochemical capacitors, also called supercapacitors, store energy using either ion adsorption (electrochemical double layer capacitors) or fast surface redox reactions (pseudo-capacitors). They can complement or replace batteries in electrical energy storage and harvesting applications, when high power delivery or uptake is needed. A notable improvement in performance has been achieved through recent advances in understanding charge storage mechanisms and the development of advanced nanostructured materials. The discovery that ion desolvation occurs in pores smaller than the solvated ions has led to higher capacitance for electrochemical double layer capacitors using carbon electrodes with subnanometre pores, and opened the door to designing high-energy density devices using a variety of electrolytes. Combination of pseudo-capacitive nanomaterials, including oxides, nitrides and polymers, with the latest generation of nanostructured lithium electrodes has brought the energy density of electrochemical capacitors closer to that of batteries. The use of carbon nanotubes has further advanced micro-electrochemical capacitors, enabling flexible and adaptable devices to be made. Mathematical modelling and simulation will be the key to success in designing tomorrow's high-energy and high-power devices. PMID:18956000

  2. Materials for electrochemical capacitors

    NASA Astrophysics Data System (ADS)

    Simon, Patrice; Gogotsi, Yury

    2008-11-01

    Electrochemical capacitors, also called supercapacitors, store energy using either ion adsorption (electrochemical double layer capacitors) or fast surface redox reactions (pseudo-capacitors). They can complement or replace batteries in electrical energy storage and harvesting applications, when high power delivery or uptake is needed. A notable improvement in performance has been achieved through recent advances in understanding charge storage mechanisms and the development of advanced nanostructured materials. The discovery that ion desolvation occurs in pores smaller than the solvated ions has led to higher capacitance for electrochemical double layer capacitors using carbon electrodes with subnanometre pores, and opened the door to designing high-energy density devices using a variety of electrolytes. Combination of pseudo-capacitive nanomaterials, including oxides, nitrides and polymers, with the latest generation of nanostructured lithium electrodes has brought the energy density of electrochemical capacitors closer to that of batteries. The use of carbon nanotubes has further advanced micro-electrochemical capacitors, enabling flexible and adaptable devices to be made. Mathematical modelling and simulation will be the key to success in designing tomorrow's high-energy and high-power devices.

  3. Capacitor discharge pulse analysis.

    SciTech Connect

    Baker, Michael Sean; Griffiths, Stewart K.; Tanner, Danelle Mary

    2013-08-01

    Capacitors used in firing sets and other high discharge current applications are discharge tested to verify performance of the capacitor against the application requirements. Parameters such as capacitance, inductance, rise time, pulse width, peak current and current reversal must be verified to ensure that the capacitor will meet the application needs. This report summarizes an analysis performed on the discharge current data to extract these parameters by fitting a second-order system model to the discharge data and using this fit to determine the resulting performance metrics. Details of the theory and implementation are presented. Using the best-fit second-order system model to extract these metrics results in less sensitivity to noise in the measured data and allows for direct extraction of the total series resistance, inductance, and capacitance.

  4. Engineering electrochemical capacitor applications

    NASA Astrophysics Data System (ADS)

    Miller, John R.

    2016-09-01

    Electrochemical capacitor (EC) applications have broadened tremendously since EC energy storage devices were introduced in 1978. Then typical applications operated below 10 V at power levels below 1 W. Today many EC applications operate at voltages approaching 1000 V at power levels above 100 kW. This paper briefly reviews EC energy storage technology, shows representative applications using EC storage, and describes engineering approaches to design EC storage systems. Comparisons are made among storage systems designed to meet the same application power requirement but using different commercial electrochemical capacitor products.

  5. Promethium-147 capacitor.

    PubMed

    Kavetskiy, A; Yakubova, G; Lin, Q; Chan, D; Yousaf, S M; Bower, K; Robertson, J D; Garnov, A; Meier, D

    2009-06-01

    Beta particle surface fluxes for tritium, Ni-63, Pm-147, and Sr-90 sources were calculated in this work. High current density was experimentally achieved from Pm-147 oxide in silica-titana glass. A 96 GBq (2.6 Ci) Pm-147 4pi-source with flux efficiency greater than 50% was used for constructing a direct charge capacitor with a polyimide coated collector and vacuum as electrical insulation. The capacitor connected to high resistance (TOmega) loads produced up to 35 kV. Overall conversion efficiency was over 10% (on optimal load). PMID:19328703

  6. High Energy Density Electrolytic Capacitor

    NASA Technical Reports Server (NTRS)

    Evans, David A.

    1996-01-01

    A new type of electrolytic capacitor which combines an electrolytic capacitor anode with an electrochemical capacitor cathode was developed. The resulting capacitor has a four time higher energy density than standard electrolytic capacitors, with comparable electric performance. The prototype, a 480 microFarad, 200 V device, has an energy density exceeding 4 J/cc. Now a 680 microFarad 50 V, MIL-style all tantalum device has been constructed and is undergoing qualification testing. Pending a favorable outcome, work will begin on other ratings. The potential for commercially significant development exists in applying this technology to aluminum-based electrolytic capacitors. It is possible to at least double the energy density of aluminum electrolytics, while using existing manufacturing methods, and without adding material expense. Data presented include electrical characteristics and performance measurements of the 200 V and 50 V hybrid capacitors and results from ongoing qualification testing of the MIL-style tantalum capacitors.

  7. High energy density electrolytic capacitor

    NASA Technical Reports Server (NTRS)

    Evans, David A.

    1995-01-01

    Recently a new type of electrolytic capacitor was developed. This capacitor, the Evans Hybrid, combines an electrolytic capacitor anode with an electrochemical capacitors cathode. The resulting capacitor has four times the energy density of other electrolytic capacitors, with comparable electrical performance. The prototype, a 480 micro F, 200 V device, had an energy density exceeding 4 J/cc. Now, a 680 micro F, 50 V, MIL-style all tantalum device has been constructed and is undergoing qualification testing. Pending a favorable outcome, work will begin on other ratings. Potential for commercially significant development exists in applying this technology to aluminum-based electrolytic capacitors. It is possible to at least double the energy density of aluminum electrolytics, while using existing manufacturing methods, and without adding material expense. Data presented include electrical characteristics and performance measurements of the 200 V and 50 V Hybrid capacitors and results of ongolng qualification status of the MJL-style tantalum.

  8. Capacitor Technologies, Applications and Reliability

    NASA Technical Reports Server (NTRS)

    1981-01-01

    Various aspects of capacitor technologies and applications are discussed. Major emphasis is placed on: the causes of failures; accelerated testing; screening tests; destructive physical analysis; applications techniques; and improvements in capacitor capabilities.

  9. Automated System Tests Ferroelectric Capacitors

    NASA Technical Reports Server (NTRS)

    Lakata, Mark; Thakoor, Sarita

    1994-01-01

    Polarization-switching parameters measured under computer control. Ferroelectric-capacitor-testing system applies voltage pulses and measures responses of ferroelectric capacitor to determine write; "time dependence of polarization," polarization-retention and fatigue characteristics of capacitor. Highly integrated setup quite flexible, versatile, and interactive, and allows convenient computer storage and analysis of data.

  10. Asymmetrical Capacitors for Propulsion

    NASA Technical Reports Server (NTRS)

    Canning, Francis X.; Melcher, Cory; Winet, Edwin

    2004-01-01

    Asymmetrical Capacitor Thrusters have been proposed as a source of propulsion. For over eighty years, it has been known that a thrust results when a high voltage is placed across an asymmetrical capacitor, when that voltage causes a leakage current to flow. However, there is surprisingly little experimental or theoretical data explaining this effect. This paper reports on the results of tests of several Asymmetrical Capacitor Thrusters (ACTs). The thrust they produce has been measured for various voltages, polarities, and ground configurations and their radiation in the VHF range has been recorded. These tests were performed at atmospheric pressure and at various reduced pressures. A simple model for the thrust was developed. The model assumed the thrust was due to electrostatic forces on the leakage current flowing across the capacitor. It was further assumed that this current involves charged ions which undergo multiple collisions with air. These collisions transfer momentum. All of the measured data was consistent with this model. Many configurations were tested, and the results suggest general design principles for ACTs to be used for a variety of purposes.

  11. Multilevel Model Prediction

    ERIC Educational Resources Information Center

    Frees, Edward W.; Kim, Jee-Seon

    2006-01-01

    Multilevel models are proven tools in social research for modeling complex, hierarchical systems. In multilevel modeling, statistical inference is based largely on quantification of random variables. This paper distinguishes among three types of random variables in multilevel modeling--model disturbances, random coefficients, and future response…

  12. Flying wings / flying fuselages

    NASA Technical Reports Server (NTRS)

    Wood, Richard M.; Bauer, Steven X. S.

    2001-01-01

    The present paper has documented the historical relationships between various classes of all lifting vehicles, which includes the flying wing, all wing, tailless, lifting body, and lifting fuselage. The diversity in vehicle focus was to ensure that all vehicle types that map have contributed to or been influenced by the development of the classical flying wing concept was investigated. The paper has provided context and perspective for present and future aircraft design studies that may employ the all lifting vehicle concept. The paper also demonstrated the benefit of developing an understanding of the past in order to obtain the required knowledge to create future concepts with significantly improved aerodynamic performance.

  13. Hermetically sealed aluminum electrolytic capacitor

    NASA Technical Reports Server (NTRS)

    Alwitt, Robert S.; Liu, Yanming; Elias, William

    1995-01-01

    Aluminum electrolytic capacitors are presently not allowed on NASA missions because they outgas water and organic vapors, as well as H2. As a consequence, much larger and heavier packages of tantalum capacitors are used. A hermetically sealed aluminum capacitor has been developed under NASA-MSFC SBIR contracts. This capacitor contains a nongassing electrolyte that was developed for this application so internal pressure would remain low. Capacitors rated at 250 to 540 V have been operated under full load for thousands of hours at 85 and 105 C with good electrical performance and low internal pressure. Electrolyte chemistry and seal engineering concepts will be discussed.

  14. Refrigerant directly cooled capacitors

    DOEpatents

    Hsu, John S.; Seiber, Larry E.; Marlino, Laura D.; Ayers, Curtis W.

    2007-09-11

    The invention is a direct contact refrigerant cooling system using a refrigerant floating loop having a refrigerant and refrigeration devices. The cooling system has at least one hermetic container disposed in the refrigerant floating loop. The hermetic container has at least one electronic component selected from the group consisting of capacitors, power electronic switches and gating signal module. The refrigerant is in direct contact with the electronic component.

  15. Advanced double layer capacitors

    NASA Technical Reports Server (NTRS)

    Sarangapani, S.; Lessner, P.; Forchione, J.; Griffith, A.; Laconti, A. B.

    1989-01-01

    Work was conducted that could lead to a high energy density electrochemical capacitor, completely free of liquid electrolyte. A three-dimensional RuO sub x-ionomer composite structure has been successfully formed and appears to provide an ionomer ionic linkage throughout the composite structure. Capacitance values of approximately 0.6 F/sq cm were obtained compared with 1 F/sq cm when a liquid electrolyte is used with the same configuration.

  16. Electrochemical fabrication of capacitors

    DOEpatents

    Mansour, Azzam N.; Melendres, Carlos A.

    1999-01-01

    A film of nickel oxide is anodically deposited on a graphite sheet held in osition on an electrochemical cell during application of a positive electrode voltage to the graphite sheet while exposed to an electrolytic nickel oxide solution within a volumetrically variable chamber of the cell. An angularly orientated x-ray beam is admitted into the cell for transmission through the deposited nickel oxide film in order to obtain structural information while the film is subject to electrochemical and in-situ x-ray spectroscopy from which optimum film thickness, may be determined by comparative analysis for capacitor fabrication purposes.

  17. Electrochemical fabrication of capacitors

    SciTech Connect

    Mansour, A.N.; Melendres, C.A.

    1999-12-14

    A film of nickel oxide is anodically deposited on a graphite sheet held in position on an electrochemical cell during application of a positive electrode voltage to the graphite sheet while exposed to an electrolytic nickel oxide solution within a volumetrically variable chamber of the cell. An angularly orientated x-ray beam is admitted into the cell for transmission through the deposited nickel oxide film in order to obtain structural information while the film is subject to electrochemical and in-situ x-ray spectroscopy from which optimum film thickness, may be determined by comparative analysis for capacitor fabrication purposes.

  18. Modulation Extension Control of Hybrid Cascaded H-Bridge Multilevel Converters with 7-Level Fundamental Frequency Switching Scheme

    SciTech Connect

    Du, Zhong; Ozpineci, Burak; Tolbert, Leon M

    2007-01-01

    This paper presents a modulation extension control algorithm for hybrid cascaded H-bridge multilevel converters. The hybrid cascaded H-bridge multilevel motor drive using only a single DC source for each phase is promising for high power motor drive applications since it can greatly decrease the number of required DC power supplies, has high quality output power due to its high number of output levels, and has high conversion efficiency and low thermal stress by using fundamental frequency switching scheme. But one disadvantage of the 7-level fundamental frequency switching scheme is that its modulation index range is too narrow when capacitor's voltage balance is maintained. The proposed modulation extension control algorithm can greatly increase capacitors' charging time and decrease the capacitors' discharging time by injecting triplen harmonics to extend the modulation index range of the hybrid cascaded H-bridge multilevel converters.

  19. A Simple, Successful Capacitor Lab

    ERIC Educational Resources Information Center

    Ennis, William

    2011-01-01

    Capacitors are a fundamental component of modern electronics. They appear in myriad devices and in an enormous range of sizes. Although our students are taught the function and analysis of capacitors, few have the opportunity to use them in our labs.

  20. Multilevel and Diverse Classrooms

    ERIC Educational Resources Information Center

    Baurain, Bradley, Ed.; Ha, Phan Le, Ed.

    2010-01-01

    The benefits and advantages of classroom practices incorporating unity-in-diversity and diversity-in-unity are what "Multilevel and Diverse Classrooms" is all about. Multilevel classrooms--also known as mixed-ability or heterogeneous classrooms--are a fact of life in ESOL programs around the world. These classrooms are often not only multilevel…

  1. Multilevel Mixture Factor Models

    ERIC Educational Resources Information Center

    Varriale, Roberta; Vermunt, Jeroen K.

    2012-01-01

    Factor analysis is a statistical method for describing the associations among sets of observed variables in terms of a small number of underlying continuous latent variables. Various authors have proposed multilevel extensions of the factor model for the analysis of data sets with a hierarchical structure. These Multilevel Factor Models (MFMs)…

  2. Towards Prognostics of Electrolytic Capacitors

    NASA Technical Reports Server (NTRS)

    Celaya, Jose R.; Kulkarni, Chetan; Biswas, Gautam; Goegel, Kai

    2011-01-01

    A remaining useful life prediction algorithm and degradation model for electrolytic capacitors is presented. Electrolytic capacitors are used in several applications ranging from power supplies on critical avionics equipment to power drivers for electro-mechanical actuators. These devices are known for their low reliability and given their criticality in electronics subsystems they are a good candidate for component level prognostics and health management research. Prognostics provides a way to assess remaining useful life of a capacitor based on its current state of health and its anticipated future usage and operational conditions. In particular, experimental results of an accelerated aging test under electrical stresses are presented. The capacitors used in this test form the basis for a remaining life prediction algorithm where a model of the degradation process is suggested. This preliminary remaining life prediction algorithm serves as a demonstration of how prognostics methodologies could be used for electrolytic capacitors.

  3. Applications of cascade multilevel inverters.

    PubMed

    Peng, Fang-zen; Qian, Zhao-ming

    2003-01-01

    Cascade multilevel inverters have been developed for electric utility applications. A cascade M-level inverter consists of (M-1)/2 H-bridges in which each bridge's dc voltage is supported by its own dc capacitor. The new inverter can: (1) generate almost sinusoidal waveform voltage while only switching one time per fundamental cycle; (2) dispense with multi-pulse inverters' transformers used in conventional utility interfaces and static var compensators; (3) enables direct parallel or series transformer-less connection to medium- and high-voltage power systems. In short, the cascade inverter is much more efficient and suitable for utility applications than traditional multi-pulse and pulse width modulation (PWM) inverters. The authors have experimentally demonstrated the superiority of the new inverter for power supply, (hybrid) electric vehicle (EV) motor drive, reactive power (var) and harmonic compensation. This paper summarizes the features, feasibility, and control schemes of the cascade inverter for utility applications including utility interface of renewable energy, voltage regulation, var compensation, and harmonic filtering in power systems. Analytical, simulated, and experimental results demonstrated the superiority of the new inverters. PMID:14566981

  4. Moisture in multilayer ceramic capacitors

    NASA Astrophysics Data System (ADS)

    Donahoe, Daniel Noel

    When both precious metal electrode and base metal electrode (BME) capacitors were subjected to autoclave (120°C/100% RH) testing, it was found that the precious metal capacitors aged according to a well known aging mechanism (less than 3% from their starting values), but the BME capacitors degraded to below the -30% criterion at 500 hours of exposure. The reasons for this new failure mechanism are complex, and there were two theories that were hypothesized. The first was that there could be oxidation or corrosion of the nickel plates. The other hypothesis was that the loss of capacitance was due to molecular changes in the barium titanate. This thesis presents the evaluation of these hypotheses and the physics of the degradation mechanism. It is concluded by proof by elimination that there are molecular changes in the barium titanate. Furthermore, the continuous reduction in capacitor size makes the newer base metal electrode capacitors more vulnerable to moisture degradation than the older generation precious metal capacitors. In addition, standard humidity life testing, such as JESD-22 THB and HAST, will likely not uncover this problem. Therefore, poor reliability due to degradation of base metal electrode multilayer ceramic capacitors may catch manufacturers and consumers by surprise.

  5. Process for manufacturing tantalum capacitors

    DOEpatents

    Lauf, Robert J.; Holcombe, Cressie E.; Dykes, Norman L.

    1993-01-01

    A process for manufacturing tantalum capacitors in which microwave energy is used to sinter a tantalum powder compact in order to achieve higher surface area and improved dielectric strength. The process comprises cold pressing tantalum powder with organic binders and lubricants to form a porous compact. After removal of the organics, the tantalum compact is heated to 1300.degree. to 2000.degree. C. by applying microwave radiation. Said compact is then anodized to form a dielectric oxide layer and infiltrated with a conductive material such as MnO.sub.2. Wire leads are then attached to form a capacitor to said capacitor is hermetically packaged to form the finished product.

  6. Process for manufacturing tantalum capacitors

    DOEpatents

    Lauf, R.J.; Holcombe, C.E.; Dykes, N.L.

    1993-02-02

    A process for manufacturing tantalum capacitors in which microwave energy is used to sinter a tantalum powder compact in order to achieve higher surface area and improved dielectric strength. The process comprises cold pressing tantalum powder with organic binders and lubricants to form a porous compact. After removal of the organics, the tantalum compact is heated to 1,300 to 2,000 C by applying microwave radiation. Said compact is then anodized to form a dielectric oxide layer and infiltrated with a conductive material such as MnO[sub 2]. Wire leads are then attached to form a capacitor to said capacitor is hermetically packaged to form the finished product.

  7. Multilevel filtering elliptic preconditioners

    NASA Technical Reports Server (NTRS)

    Kuo, C. C. Jay; Chan, Tony F.; Tong, Charles

    1989-01-01

    A class of preconditioners is presented for elliptic problems built on ideas borrowed from the digital filtering theory and implemented on a multilevel grid structure. They are designed to be both rapidly convergent and highly parallelizable. The digital filtering viewpoint allows the use of filter design techniques for constructing elliptic preconditioners and also provides an alternative framework for understanding several other recently proposed multilevel preconditioners. Numerical results are presented to assess the convergence behavior of the new methods and to compare them with other preconditioners of multilevel type, including the usual multigrid method as preconditioner, the hierarchical basis method and a recent method proposed by Bramble-Pasciak-Xu.

  8. Multilevel ensemble Kalman filtering

    DOE PAGESBeta

    Hoel, Hakon; Law, Kody J. H.; Tempone, Raul

    2016-06-14

    This study embeds a multilevel Monte Carlo sampling strategy into the Monte Carlo step of the ensemble Kalman filter (EnKF) in the setting of finite dimensional signal evolution and noisy discrete-time observations. The signal dynamics is assumed to be governed by a stochastic differential equation (SDE), and a hierarchy of time grids is introduced for multilevel numerical integration of that SDE. Finally, the resulting multilevel EnKF is proved to asymptotically outperform EnKF in terms of computational cost versus approximation accuracy. The theoretical results are illustrated numerically.

  9. Polyvinylidene fluoride film as a capacitor dielectric

    NASA Technical Reports Server (NTRS)

    Dematos, H. V.

    1981-01-01

    Thin strips of polyvinylidene fluoride film (PVDF) with vacuum deposited electrodes were made into capacitors by conventional winding and fabrication techniques. These devices were used to identify and evaluate the performance characteristics offered by the PVDF in metallized film capacitors. Variations in capacitor parameters with temperature and frequence were evaluated and compared with other dielectric films. Their impact on capacitor applications is discussed.

  10. 49 CFR 173.176 - Capacitors.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 2 2013-10-01 2013-10-01 false Capacitors. 173.176 Section 173.176 Transportation... PACKAGINGS Non-bulk Packaging for Hazardous Materials Other Than Class 1 and Class 7 § 173.176 Capacitors. (a) Capacitors, including capacitors containing an electrolyte that does not meet the definition of any...

  11. 49 CFR 173.176 - Capacitors.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 2 2014-10-01 2014-10-01 false Capacitors. 173.176 Section 173.176 Transportation... PACKAGINGS Non-bulk Packaging for Hazardous Materials Other Than Class 1 and Class 7 § 173.176 Capacitors. (a) Capacitors, including capacitors containing an electrolyte that does not meet the definition of any...

  12. Ferroelectric capacitor with reduced imprint

    DOEpatents

    Evans, Jr., Joseph T.; Warren, William L.; Tuttle, Bruce A.; Dimos, Duane B.; Pike, Gordon E.

    1997-01-01

    An improved ferroelectric capacitor exhibiting reduced imprint effects in comparison to prior art capacitors. A capacitor according to the present invention includes top and bottom electrodes and a ferroelectric layer sandwiched between the top and bottom electrodes, the ferroelectric layer comprising a perovskite structure of the chemical composition ABO.sub.3 wherein the B-site comprises first and second elements and a dopant element that has an oxidation state greater than +4. The concentration of the dopant is sufficient to reduce shifts in the coercive voltage of the capacitor with time. In the preferred embodiment of the present invention, the ferroelectric element comprises Pb in the A-site, and the first and second elements are Zr and Ti, respectively. The preferred dopant is chosen from the group consisting of Niobium, Tantalum, and Tungsten. In the preferred embodiment of the present invention, the dopant occupies between 1 and 8% of the B-sites.

  13. Hermetically Sealed Aluminum Electrolytic Capacitor

    NASA Technical Reports Server (NTRS)

    Alwitt, Robert S.; Liu, Yanming; Elias, William

    1996-01-01

    Aluminum electrolytic capacitors are presently not allowed on NASA missions because they outgas water and organic vapors, as well as H2. As a consequence, for some applications, much larger and heavier packages of tantalum capacitors must be used. A hermetically sealed aluminum capacitor has been developed. This contains a nongassing electrolyte that was developed for this application so internal pressure would remain low. Capacitors rated from 250 V to 540 V have been operated under full load for thousands of hours at 85 and 105 C with good electrical performance and absence of gas generation. Electrolyte chemistry and seal engineering will be discussed, as well as the extension of this design concept to lower voltage ratings.

  14. A Five-Level Cascade Multilevel Inverter Three-Phase Motor Drive Using a Single DC Source

    SciTech Connect

    Chiasson, J. N.

    2006-10-01

    A method is presented showing that a 5-level cascade multilevel inverter for a three-phase permanent magnet sychronous motor drive can be implemented using only a single DC link to supply a standard 3-leg inverter along with three full H-bridges supplied by capacitors. It is shown that the capacitor voltages can be regulated while achieving an output voltage waveform that is 20% greater than that obained using the standard 3-leg inverter alone. Finally conditions are given in terms of the power factor and modulation index that determine when the capacitor voltage can regulated.

  15. PLZT capacitor on glass substrate

    DOEpatents

    Fairchild, M. Ray; Taylor, Ralph S.; Berlin, Carl W.; Wong, Celine W. K.; Ma, Beihai; Balachandran, Uthamalingam

    2016-01-05

    A lead-lanthanum-zirconium-titanate (PLZT) capacitor on a substrate formed of glass. The first metallization layer is deposited on a top side of the substrate to form a first electrode. The dielectric layer of PLZT is deposited over the first metallization layer. The second metallization layer deposited over the dielectric layer to form a second electrode. The glass substrate is advantageous as glass is compatible with an annealing process used to form the capacitor.

  16. PLZT capacitor on glass substrate

    DOEpatents

    Fairchild, Manuel Ray; Taylor, Ralph S.; Berlin, Carl W.; Wong, Celine Wk; Ma, Beihai; Balachandran, Uthamalingam

    2016-03-29

    A lead-lanthanum-zirconium-titanate (PLZT) capacitor on a substrate formed of glass. The first metallization layer is deposited on a top side of the substrate to form a first electrode. The dielectric layer of PLZT is deposited over the first metallization layer. The second metallization layer deposited over the dielectric layer to form a second electrode. The glass substrate is advantageous as glass is compatible with an annealing process used to form the capacitor.

  17. Technology of Pulse Power Capacitors

    NASA Astrophysics Data System (ADS)

    Qin, Shanshan

    Polymer film of pulse discharge capacitors operated at high repetition rate dissipates substantial power. The thermal conductivity of biaxially oriented polypropylene (BOPP) is measured as a function of metallization resistivity. The thermal conductivity in the plane of the film is about twice that of bulk polypropylene. Thermal design is optimized based on the measurement for large capacitors with multiple windings in a container. High discharge speed results in high current density at the wire arc sprayed end connections which tend to deteriorate gradually, resulting in capacitor failure during operation. To assure the end connection quality before assembly, a test procedure and apparatus for end connection integrity was developed based on monitoring the partial discharge pattern from end connection during discharge. The mechanism of clearing is analyzed which shows arc extinguishes due to the increased arc length and reduced energy so that capacitor can function normally after breakdown. In the case of a clearing discharge, the power dissipation appears to increase with time, although this is not a feature of previous models. Submicrosecond discharge requires minimizing inductance which can be achieved by optimizing the winding structure so that submicrosecond discharge becomes practical. An analysis of the inductance of multisection, very high voltage capacitors is carried out, which identifies low inductance structures for this type of capacitor.

  18. Flying Cars

    NASA Technical Reports Server (NTRS)

    Crow, Steven

    1996-01-01

    Flying cars have nearly mythical appeal to nonpilots, a group that includes almost the whole human race. The appeal resides in the perceived utility of flying cars, vehicles that offer portal-to-portal transportation, yet break the bonds of road and traffic and travel freely through the sky at the drivers will. Part of the appeal is an assumption that flying cars can be as easy to fly as to drive. Flying cars have been part of the dream of aviation since the dawn of powered flight. Glenn Curtiss built, displayed, and maybe even flew a flying car in 1917, the Curtiss Autoplane. Many roadable airplanes were built in the 1930's, like the Waterman Arrowbile and the Fulton Airphibian. Two flying cars came close to production in the early 1950's. Ted Hall built a series of flying cars culminating in the Convaircar, sponsored by Consolidated Vultee, General Motors, and Hertz. Molt Taylor built and certified his Aerocar, and Ford came close to producing them. Three Aerocars are still flyable, two in museums in Seattle and Oshkosh, and the third owned and flown by Ed Sweeny. Flying cars do have problems, which so far have prevented commercial success. An obvious problem is complexity of the vehicle, the infrastructure, or both. Another is the difficulty of matching low power for normal driving with high power in flight. An automobile uses only about 20 hp at traffic speeds, while a personal airplane needs about 160 hp at speeds typical of flight. Many automobile engines can deliver 160 hp, but not for very long. A more subtle issue involves the drag of automobiles and airplanes. A good personal airplane can fly 30 miles per gallon of fuel at 200 mph. A good sports car would need 660 hp at the same speed and would travel only 3 miles per gallon. The difference is drag area, about 4.5 sq ft for the automobile and 1.4 sq ft for the airplane. A flying car better have the drag area of the airplane, not the car!

  19. High-Energy-Density Capacitors

    NASA Technical Reports Server (NTRS)

    Slenes, Kirk

    2003-01-01

    Capacitors capable of storing energy at high densities are being developed for use in pulse-power circuits in such diverse systems as defibrillators, particle- beam accelerators, microwave sources, and weapons. Like typical previously developed energy-storage capacitors, these capacitors are made from pairs of metal/solid-dielectric laminated sheets that are wound and pressed into compact shapes to fit into cans, which are then filled with dielectric fluids. Indeed, these capacitors can be fabricated largely by conventional fabrication techniques. The main features that distinguish these capacitors from previously developed ones are improvements in (1) the selection of laminate materials, (2) the fabrication of the laminated sheets from these materials, and (3) the selection of dielectric fluids. In simplest terms, a high-performance laminated sheet of the type used in these capacitors is made by casting a dielectric polymer onto a sheet of aluminized kraft paper. The dielectric polymer is a siloxane polymer that has been modified with polar pendant groups to increase its permittivity and dielectric strength. Potentially, this polymer is capable of withstanding an energy density of 7.5 J/cm3, which is four times that of the previous state-of-the-art-capacitor dielectric film material. However, the full potential of this polymer cannot be realized at present because (1) at thicknesses needed for optimum performance (.8.0 m), the mechanical strength of a film of this polymer is insufficient for incorporation into a wound capacitor and (2) at greater thickness, the achievable energy density decreases because of a logarithmic decrease in dielectric strength with increasing thickness. The aluminized kraft paper provides the mechanical strength needed for processing of the laminate and fabrication of the capacitor, and the aluminum film serves as an electrode layer. Because part of the thickness of the dielectric is not occupied by the modified siloxane polymer, the

  20. Analysis of a transformer-less, multi-level DC-DC converter for HVDC operation

    SciTech Connect

    Karady, G.G.; Devarajan, S.

    1998-12-31

    HVDC systems require DC step up and DC step down units. The traditional approach is the application of twelve-pulse thyristor bridges with transformers. The developments of fast switching IGBT devices permit the development of transformer-less, multi-level converters. A multi-level circuit was suggested by Limpaecher. This paper presents a detailed simulation of the proposed circuit together with the analysis of its performance. The converter consists of a set of capacitors, air core inductors and solid state switches arranged in a ladder network. In the step-up mode, the closing of solid state switches resonantly charges the capacitors in parallel through an air-cored inductor. Then solid state switches resonantly charges the capacitors in parallel through an air-cored inductor. Then solid state switches connect the capacitors in series and discharge them through an air-core inductor to the load. In the step-down mode the capacitors are charged in series and discharged in parallel. The circuit has three modes of operation in each cycle: charge, inversion, and discharge. The circuit operation is analyzed in each mode using SPICE simulations. The selection of the components is discussed and output voltage regulation is analyzed. The results show that the proposed circuit promises significant reduction of losses, because of the zero current switching. The investment cost is reduced because of the elimination of transformers.

  1. Shapeable short circuit resistant capacitor

    DOEpatents

    Taylor, Ralph S.; Myers, John D.; Baney, William J.

    2015-10-06

    A ceramic short circuit resistant capacitor that is bendable and/or shapeable to provide a multiple layer capacitor that is extremely compact and amenable to desirable geometries. The capacitor that exhibits a benign failure mode in which a multitude of discrete failure events result in a gradual loss of capacitance. Each event is a localized event in which localized heating causes an adjacent portion of one or both of the electrodes to vaporize, physically cleaning away electrode material from the failure site. A first metal electrode, a second metal electrode, and a ceramic dielectric layer between the electrodes are thin enough to be formed in a serpentine-arrangement with gaps between the first electrode and the second electrode that allow venting of vaporized electrode material in the event of a benign failure.

  2. Miniature capacitor functions as pressure sensor

    NASA Technical Reports Server (NTRS)

    Harrison, R. G.

    1967-01-01

    Miniature capacitor operates as a differential pressure telemetry sensor during free flight of test model in a hypersonic wind tunnel. The capacitor incorporates a beryllium copper diaphragm. It is also used as an absolute pressure sensor.

  3. Super miniaturization of film capacitor dielectrics

    NASA Technical Reports Server (NTRS)

    Lavene, B.

    1981-01-01

    The alignment of the stable electrical characteristics of film capacitors in the physical dimensions of ceramic and tantalum capacitors are discussed. The reliability of polycarbonate and mylar capacitors are described with respect to their compatibility with military specifications. Graphic illustrations are presented which show electrical and physical comparisons of film, ceramic, and tantalum capacitors. The major focus is on volumetric efficiency, weight reduction, and electrical stability.

  4. Super Capacitor Development At NASA MSFC

    NASA Technical Reports Server (NTRS)

    Hall, David K.

    2000-01-01

    A viewgraph presentation outlines super capacitor development at NASA Marshall Space Flight Center. The concept, proof of concept testing and the test set-ups are described. An overview of super capacitor classification is shown and several types of capacitors are detailed: Ni-C chemical double layer (CDL), Ru-Oxide pseudo-cap, and a Ru-Oxide 2 F 30 V capacitor.

  5. Capacitor-Chain Successive-Approximation ADC

    NASA Technical Reports Server (NTRS)

    Cunningham, Thomas

    2003-01-01

    A proposed successive-approximation analog-to-digital converter (ADC) would contain a capacitively terminated chain of identical capacitor cells. Like a conventional successive-approximation ADC containing a bank of binary-scaled capacitors, the proposed ADC would store an input voltage on a sample-and-hold capacitor and would digitize the stored input voltage by finding the closest match between this voltage and a capacitively generated sum of binary fractions of a reference voltage (Vref). However, the proposed capacitor-chain ADC would offer two major advantages over a conventional binary-scaled-capacitor ADC: (1) In a conventional ADC that digitizes to n bits, the largest capacitor (representing the most significant bit) must have 2(exp n-1) times as much capacitance, and hence, approximately 2(exp n-1) times as much area as does the smallest capacitor (representing the least significant bit), so that the total capacitor area must be 2(exp n) times that of the smallest capacitor. In the proposed capacitor-chain ADC, there would be three capacitors per cell, each approximately equal to the smallest capacitor in the conventional ADC, and there would be one cell per bit. Therefore, the total capacitor area would be only about 3(exp n) times that of the smallest capacitor. The net result would be that the proposed ADC could be considerably smaller than the conventional ADC. (2) Because of edge effects, parasitic capacitances, and manufacturing tolerances, it is difficult to make capacitor banks in which the values of capacitance are scaled by powers of 2 to the required precision. In contrast, because all the capacitors in the proposed ADC would be identical, the problem of precise binary scaling would not arise.

  6. Tunable circuit for tunable capacitor devices

    SciTech Connect

    Rivkina, Tatiana; Ginley, David S.

    2006-09-19

    A tunable circuit (10) for a capacitively tunable capacitor device (12) is provided. The tunable circuit (10) comprises a tunable circuit element (14) and a non-tunable dielectric element (16) coupled to the tunable circuit element (16). A tunable capacitor device (12) and a method for increasing the figure of merit in a tunable capacitor device (12) are also provided.

  7. Process for manufacturing multilayer capacitors

    DOEpatents

    Lauf, R.J.; Holcombe, C.E.; Dykes, N.L.

    1996-01-02

    The invention is directed to a method of manufacture of multilayer electrical components, especially capacitors, and components made by such a method. High capacitance dielectric materials and low cost metallizations layered with such dielectrics may be fabricated as multilayer electrical components by sintering the metallizations and the dielectrics during the fabrication process by application of microwave radiation. 4 figs.

  8. Process for manufacturing multilayer capacitors

    DOEpatents

    Lauf, Robert J.; Holcombe, Cressie E.; Dykes, Norman L.

    1996-01-01

    The invention is directed to a method of manufacture of multilayer electrical components, especially capacitors, and components made by such a method. High capacitance dielectric materials and low cost metallizations layered with such dielectrics may be fabricated as multilayer electrical components by sintering the metallizations and the dielectrics during the fabrication process by application of microwave radiation.

  9. Method of making tantalum capacitors

    DOEpatents

    McMillan, April D.; Clausing, Robert E.; Vierow, William F.

    1998-01-01

    A method for manufacturing tantalum capacitors includes preparing a tantalum compact by cold pressing tantalum powder, placing the compact, along with loose refractory metal powder, in a microwave-transparent casket to form an assembly, and heating the assembly for a time sufficient to effect at least partial sintering of the compact and the product made by the method.

  10. All-tantalum electrolytic capacitor

    NASA Technical Reports Server (NTRS)

    Green, G. E., Jr.

    1977-01-01

    Device uses single-compression tantalum-to-tantalum seal. Single-compression seal allows better utilization of volume within device. As result of all-tantalum case and lengthened cathode, electrical parameters, particularly equivalent series resistance and capacitance stability, improved over silver-cased capacitor.

  11. Research on high energy density capacitor materials

    NASA Technical Reports Server (NTRS)

    Somoano, Robert

    1988-01-01

    The Pulsed Plasma thruster is the simplest of all electric propulsion devices. It is a pulsed device which stores energy in capacitors for each pulse. The lifetimes and energy densities of these capacitors are critical parameters to the continued use of these thrusters. This report presents the result of a research effort conducted by JPL into the materials used in capacitors and the modes of failure. The dominant failure mechanism was determined to be material breakdown precipitated by heat build-up within the capacitors. The presence of unwanted gas was identified as the source of the heat. An aging phenomena was discovered in polycarbonate based capacitors. CO build-up was noted to increase with the number of times the capacitor had been discharged. Improved quality control was cited as being essential for the improvement of capacitor lifetimes.

  12. Multilevel Interventions: Measurement and Measures

    PubMed Central

    Charns, Martin P.; Alligood, Elaine C.; Benzer, Justin K.; Burgess, James F.; Mcintosh, Nathalie M.; Burness, Allison; Partin, Melissa R.; Clauser, Steven B.

    2012-01-01

    Background Multilevel intervention research holds the promise of more accurately representing real-life situations and, thus, with proper research design and measurement approaches, facilitating effective and efficient resolution of health-care system challenges. However, taking a multilevel approach to cancer care interventions creates both measurement challenges and opportunities. Methods One-thousand seventy two cancer care articles from 2005 to 2010 were reviewed to examine the state of measurement in the multilevel intervention cancer care literature. Ultimately, 234 multilevel articles, 40 involving cancer care interventions, were identified. Additionally, literature from health services, social psychology, and organizational behavior was reviewed to identify measures that might be useful in multilevel intervention research. Results The vast majority of measures used in multilevel cancer intervention studies were individual level measures. Group-, organization-, and community-level measures were rarely used. Discussion of the independence, validity, and reliability of measures was scant. Discussion Measurement issues may be especially complex when conducting multilevel intervention research. Measurement considerations that are associated with multilevel intervention research include those related to independence, reliability, validity, sample size, and power. Furthermore, multilevel intervention research requires identification of key constructs and measures by level and consideration of interactions within and across levels. Thus, multilevel intervention research benefits from thoughtful theory-driven planning and design, an interdisciplinary approach, and mixed methods measurement and analysis. PMID:22623598

  13. Fundamental Frequency Switching Control of Seven-Level Hybrid Cascaded H-bridge Multilevel Inverter

    SciTech Connect

    Du, Zhong; Chiasson, John N; Ozpineci, Burak; Tolbert, Leon M

    2009-01-01

    This paper presents a cascaded H-bridge multilevel inverter that can be implemented using only a single dc power source and capacitors. Standard cascaded multilevel inverters require n dc sources for 2n + 1 levels. Without requiring transformers, the scheme proposed here allows the use of a single dc power source (e.g., a battery or a fuel cell stack) with the remaining n-1 dc sources being capacitors, which is referred to as hybrid cascaded H-bridge multilevel inverter (HCMLI) in this paper. It is shown that the inverter can simultaneously maintain the dc voltage level of the capacitors and choose a fundamental frequency switching pattern to produce a nearly sinusoidal output. HCMLI using only a single dc source for each phase is promising for high-power motor drive applications as it significantly decreases the number of required dc power supplies, provides high-quality output power due to its high number of output levels, and results in high conversion efficiency and low thermal stress as it uses a fundamental frequency switching scheme. This paper mainly discusses control of seven-level HCMLI with fundamental frequency switching control and how its modulation index range can be extended using triplen harmonic compensation.

  14. Switched-Capacitor Voltage Multiplier

    NASA Technical Reports Server (NTRS)

    Sridharan, Govind

    1991-01-01

    Dc-to-dc power converter multiplies input supply potential by factor of nearly 40. Design does not make use of transformers or inductors but effects voltage boost-up by capacitive energy transfer. Circuit primarily made up of banks of capacitors, connected by network of integrated-circuit relays. Converter functionally linear voltage amplifier with fixed gain figure. Bipolar in operation. Output fully floating, and excellent dc isolation between input and output terminals.

  15. Characterization of Tantalum Polymer Capacitors

    NASA Technical Reports Server (NTRS)

    Spence, Penelope

    2012-01-01

    Overview Reviewed data Caution must be taken when accelerating test conditions Data not useful to establish an acceleration model Introduction of new failure mechanism skewing results Evidence of Anti-Wear-Out De-doping of polymer Decreased capacitance Increased ESR Not dielectric breakdown Needs further investigation Further investigation into tantalum polymer capacitor technology Promising acceleration model for Manufacturer A Possibility for use in high-reliability space applications with suitable voltage derating.

  16. Recent developments in multilevel optimization

    NASA Technical Reports Server (NTRS)

    Vanderplaats, Garret N.; Kim, D.-S.

    1989-01-01

    Recent developments in multilevel optimization are briefly reviewed. The general nature of the multilevel design task, the use of approximations to develop and solve the analysis design task, the structure of the formal multidiscipline optimization problem, a simple cantilevered beam which demonstrates the concepts of multilevel design and the basic mathematical details of the optimization task and the system level are among the topics discussed.

  17. Capacitor-type micrometeoroid detectors

    NASA Technical Reports Server (NTRS)

    Wortman, J. J.; Griffis, D. P.; Bryan, S. R.; Kinard, W.

    1986-01-01

    The metal oxide semiconductor (MOS) capacitor micrometeroid detector consists of a thin dielectric capacitor fabricated on a silicon wafer. In operation, the device is charged to a voltage level sufficiently near breakdown that micrometeoroid impacts will cause dielectric deformation or heating and subsequent arc-over at the point of impact. Each detector is capable of recording multiple impacts because of the self-healing characteristics of the device. Support instrumentation requirements consist of a voltage source and pulse counters that monitor the pulse of recharging current following every impact. An investigation has been conducted in which 0.5 to 5 micron diameter carbonized iron spheres traveling at velocities of 4 to 10 Km/sec were impacted on to detectors with either a dielectric thickness of 0.4 or 1.0 micron. This study demonstrated that an ion microprobe tuned to sufficiently high resolution can detect Fe remaining on the detector after the impact. Furthermore, it is also possible to resolve Fe ion images free of mass interferences from Si, for example, giving its spatial distribution after impact. Specifically this technique has shown that significant amounts of impacting particles remain in the crater and near it which can be analyzed for isotopic content. Further testing and calibration could lead to quantitive analysis. This study has shown that the capacitor type micrometeroid detector is capable of not only time and flux measurements but can also be used for isotopic analysis.

  18. Carbon-based electrochemical capacitors.

    PubMed

    Ghosh, Arunabha; Lee, Young Hee

    2012-03-12

    Supercapacitors are one of the key devices for energy-storage applications. They have energy densities much higher than those of conventional capacitors and possess much better power delivery capabilities than batteries. This makes them unique devices that can outperform both batteries and conventional capacitors under special circumstances. Nanocarbons are the main electrode materials for supercapacitors. Abundant sources of nanocarbons and facile processes of modification have led to the fabrication of cheap electrodes. In this review, we focus on the capacitance performance of highly porous activated carbons and attempt to determine the role of different pores. Elaborate discussions are presented on individual contributions from micro- and mesopores and their mutual dependence. This article also presents a comparative performance report for both random and ordered porous nanocarbons. Novel carbon materials, such as carbon nanotubes and graphene, and their contributions in this context are discussed. We summarize key techniques for the functionalization of nanocarbons and their pseudocapacitive charge-storage mechanisms. Nanocarbon composites with redox-active transition-metal oxides and conducting polymers are highlighted along with their impact as electrode materials. Ideal composite structures are highlighted and an attempt is made to determine an ideal future electrode structure for capacitors with high energy and power density. PMID:22389329

  19. Electrically Variable or Programmable Nonvolatile Capacitors

    NASA Technical Reports Server (NTRS)

    Shangqing, Liu; NaiJuan, Wu; Ignatieu, Alex; Jianren, Li

    2009-01-01

    Electrically variable or programmable capacitors based on the unique properties of thin perovskite films are undergoing development. These capacitors show promise of overcoming two important deficiencies of prior electrically programmable capacitors: Unlike in the case of varactors, it is not necessary to supply power continuously to make these capacitors retain their capacitance values. Hence, these capacitors may prove useful as components of nonvolatile analog and digital electronic memories. Unlike in the case of ferroelectric capacitors, it is possible to measure the capacitance values of these capacitors without changing the values. In other words, whereas readout of ferroelectric capacitors is destructive, readout of these capacitors can be nondestructive. A capacitor of this type is a simple two terminal device. It includes a thin film of a suitable perovskite as the dielectric layer, sandwiched between two metal or metal oxide electrodes (for example, see Figure 1). The utility of this device as a variable capacitor is based on a phenomenon, known as electrical-pulse-induced capacitance (EPIC), that is observed in thin perovskite films and especially in those thin perovskite films that exhibit the colossal magnetoresistive (CMR) effect. In EPIC, the application of one or more electrical pulses that exceed a threshold magnitude (typically somewhat less than 1 V) gives rise to a nonvolatile change in capacitance. The change in capacitance depends on the magnitude duration, polarity, and number of pulses. It is not necessary to apply a magnetic field or to cool the device below (or heat it above) room temperature to obtain EPIC. Examples of suitable CMR perovskites include Pr(1-x)Ca(x)MnO3, La(1-x)S-r(x)MnO3,and Nb(1-x)Ca(x)MnO3. Figure 2 is a block diagram showing an EPIC capacitor connected to a circuit that can vary the capacitance, measure the capacitance, and/or measure the resistance of the capacitor.

  20. Capacitors with low equivalent series resistance

    NASA Technical Reports Server (NTRS)

    Fleig, Patrick Franz (Inventor); Lakeman, Charles D. E. (Inventor); Fuge, Mark (Inventor)

    2011-01-01

    An electric double layer capacitor (EDLC) in a coin or button cell configuration having low equivalent series resistance (ESR). The capacitor comprises mesh or other porous metal that is attached via conducting adhesive to one or both the current collectors. The mesh is embedded into the surface of the adjacent electrode, thereby reducing the interfacial resistance between the electrode and the current collector, thus reducing the ESR of the capacitor.

  1. MB C220 Centering System Capacitor Fire

    NASA Technical Reports Server (NTRS)

    Worth, Daniel B.

    2003-01-01

    A detailed analysis of the MB C220 Centering System Capacitor Fire is presented. The topics include: 1) Description of Incident/Mishap; 2) System Block Diagram; 3) Fault Tree Analysis; 4) Inspection and Repair of Cabinet; 5) Discussions with GSFC Experts; 6) Electrical Measurements of Capacitors; 7) Other Research; 8) Discussions with Capacitor Manufacturers; 9) Findings/Root Cause; and 10) Recommendations. This paper is in viewgraph form.

  2. Low-Inductance Capacitor For Low Temperatures

    NASA Technical Reports Server (NTRS)

    Rhodes, David B.; Jones, Stephen B.; Franke, John M.

    1989-01-01

    Planar capacitor made on epoxy/fiberglass printed-circuit board. Planar design and flat copper plates ensure low inductance and low series resistance. Planar construction minimized effects of thermal contraction, and epoxy/fiberglass substrate ensured high breakdown voltage. Design is simple, and this type of capacitor easy for any printed-circuit-board facility to fabricate. Design suitable for any small-capacitance, high-voltage capacitor, whether operating at low or high temperature.

  3. The tantalum-cased tantalum capacitor

    NASA Technical Reports Server (NTRS)

    Moynihan, J. D.

    1977-01-01

    Tantalum-cased tantalum capacitors were tested with regard to temperature stability, capacitance ratio, surge current capabilities, shock, vibration, and thermal shock. They were found to be superior to the conventional wet slug tantalum capacitor cased in silver, since they are more resistant to sulfuric acid. The tantalum-cased tantalum capacitors are widely accepted for use in critical electronic equipment because of their excellent performance and reliability.

  4. Multilevel Modeling of Social Segregation

    ERIC Educational Resources Information Center

    Leckie, George; Pillinger, Rebecca; Jones, Kelvyn; Goldstein, Harvey

    2012-01-01

    The traditional approach to measuring segregation is based upon descriptive, non-model-based indices. A recently proposed alternative is multilevel modeling. The authors further develop the argument for a multilevel modeling approach by first describing and expanding upon its notable advantages, which include an ability to model segregation at a…

  5. A Primer on Multilevel Modeling

    ERIC Educational Resources Information Center

    Hayes, Andrew F.

    2006-01-01

    Multilevel modeling (MLM) is growing in use throughout the social sciences. Although daunting from a mathematical perspective, MLM is relatively easy to employ once some basic concepts are understood. In this article, I present a primer on MLM, describing some of these principles and applying them to the analysis of a multilevel data set on…

  6. Ultra-thin multilayer capacitors.

    SciTech Connect

    Renk, Timothy Jerome; Monson, Todd C.

    2009-06-01

    The fabrication of ultra-thin lanthanum-doped lead zirconium titanate (PLZT) multilayer ceramic capacitors (MLCCs) using a high-power pulsed ion beam was studied. The deposition experiments were conducted on the RHEPP-1 facility at Sandia National Laboratories. The goal of this work was to increase the energy density of ceramic capacitors through the formation of a multilayer device with excellent materials properties, dielectric constant, and standoff voltage. For successful device construction, there are a number of challenging requirements including achieving correct stoichiometric and crystallographic composition of the deposited PLZT, as well as the creation of a defect free homogenous film. This report details some success in satisfying these requirements, although 900 C temperatures were necessary for PLZT perovskite phase formation. These temperatures were applied to a previously deposited multi-layer film which was then post-annealed to this temperature. The film exhibited mechanical distress attributable to differences in the coefficient of thermal expansion (CTE) of the various layers. This caused significant defects in the deposited films that led to shorts across devices. A follow-on single layer deposition without post-anneal produced smooth layers with good interface behavior, but without the perovskite phase formation. These issues will need to be addressed in order for ion beam deposited MLCCs to become a viable technology. It is possible that future in-situ heating during deposition may address both the CTE issue, and result in lowered processing temperatures, which in turn could raise the probability of successful MLCC formation.

  7. Pyrrole-Based Conductive Polymers For Capacitors

    NASA Technical Reports Server (NTRS)

    Nagasubramanian, Ganesan; Di Stefano, Salvador

    1994-01-01

    Polypyrrole films containing various dopant anions exhibit superior capacitance characteristics. Used with nonaqueous electrolytes. Candidate for use in advanced electrochemical double-layer capacitors capable of storing electrical energy at high densities. Capacitors made of these films used in automobiles and pulsed power supplies.

  8. High frequency, high power capacitor development

    NASA Technical Reports Server (NTRS)

    White, C. W.; Hoffman, P. S.

    1983-01-01

    A program to develop a special high energy density, high power transfer capacitor to operate at frequency of 40 kHz, 600 V rms at 125 A rms plus 600 V dc bias for space operation. The program included material evaluation and selection, a capacitor design was prepared, a thermal analysis performed on the design. Fifty capacitors were manufactured for testing at 10 kHz and 40 kHz for 50 hours at Industrial Electric Heating Co. of Columbus, Ohio. The vacuum endurance test used on environmental chamber and temperature plate furnished by Maxwell. The capacitors were energized with a special power conditioning apparatus developed by Industrial Electric Heating Co. Temperature conditions of the capacitors were monitored by IEHCo test equipment. Successful completion of the vacuum endurance test series confirmed achievement of the main goal of producing a capacitor or reliable operation at high frequency in an environment normally not hospitable to electrical and electronic components. The capacitor developed compared to a typical commercial capacitor at the 40 kHz level represents a decrease in size and weight by a factor of seven.

  9. Semiautomated switched capacitor filter design system

    NASA Technical Reports Server (NTRS)

    Thelen, D.

    1990-01-01

    A software system is described which reduces the time required to design monolithic switched capacitor filters. The system combines several software tools into an integrated flow. Switched capacitor technology and alternative technologies are discussed. Design time using the software system is compared to typical design time without the system.

  10. Simple Ways to Make Real Capacitors

    ERIC Educational Resources Information Center

    Herman, Rhett

    2014-01-01

    Many of us have grabbed two pieces of aluminum foil and a paper towel, quickly sandwiched them together, and exclaimed in lecture, "Look! It's easy to make a capacitor!" Then we move on from there, calculating things such as capacitances with various dielectrics or plate sizes, the capacitance of capacitor networks, RC circuits,…

  11. Are the Textbook Writers Wrong about Capacitors?

    ERIC Educational Resources Information Center

    French, A. P.

    1993-01-01

    Refutes a recent article which stated that the standard textbook treatment of two capacitors in series is wrong. States that the calculated capacitance is correct if measured immediately after a dc voltage is applied and that perhaps the effect is due to the choice of materials making up the capacitor. (MVL)

  12. Simple Ways to Make Real Capacitors

    NASA Astrophysics Data System (ADS)

    Herman, Rhett

    2014-11-01

    Many of us have grabbed two pieces of aluminum foil and a paper towel, quickly sandwiched them together, and exclaimed in lecture, "Look! It's easy to make a capacitor!" Then we move on from there, calculating things such as capacitances with various dielectrics or plate sizes, the capacitance of capacitor networks, RC circuits, etc. We typically do these calculations with capacitance values that are far removed from what we just created in our quick demonstration of a capacitor. Students might justifiably question whether the capacitor that we blithely made has any relation to the values that we are using in our calculations. It may be useful to investigate the quality of such handmade capacitors so that our students get a more intuitive feel for these ubiquitous electrical components.

  13. Multilevel DC link inverter

    DOEpatents

    Su, Gui-Jia

    2003-06-10

    A multilevel DC link inverter and method for improving torque response and current regulation in permanent magnet motors and switched reluctance motors having a low inductance includes a plurality of voltage controlled cells connected in series for applying a resulting dc voltage comprised of one or more incremental dc voltages. The cells are provided with switches for increasing the resulting applied dc voltage as speed and back EMF increase, while limiting the voltage that is applied to the commutation switches to perform PWM or dc voltage stepping functions, so as to limit current ripple in the stator windings below an acceptable level, typically 5%. Several embodiments are disclosed including inverters using IGBT's, inverters using thyristors. All of the inverters are operable in both motoring and regenerating modes.

  14. Parallel multilevel preconditioners

    SciTech Connect

    Bramble, J.H.; Pasciak, J.E.; Xu, Jinchao.

    1989-01-01

    In this paper, we shall report on some techniques for the development of preconditioners for the discrete systems which arise in the approximation of solutions to elliptic boundary value problems. Here we shall only state the resulting theorems. It has been demonstrated that preconditioned iteration techniques often lead to the most computationally effective algorithms for the solution of the large algebraic systems corresponding to boundary value problems in two and three dimensional Euclidean space. The use of preconditioned iteration will become even more important on computers with parallel architecture. This paper discusses an approach for developing completely parallel multilevel preconditioners. In order to illustrate the resulting algorithms, we shall describe the simplest application of the technique to a model elliptic problem.

  15. On lossless switched-capacitor power converters

    SciTech Connect

    Tse, C.K.; Wong, S.C.; Chow, M.H.L.

    1995-05-01

    This paper addresses the design of efficient switched-capacitor power converters. The discussion starts with a review of the fundamental limitation of switched-capacitor circuits which shows that the topology of such circuits and the ``forced`` step changes of capacitor voltages are the inherent attributes of power loss. Although the argument follows from a rather trivial result from basic circuit theory, it addresses an important issue on the maximum efficiency achievable in a switched-capacitor converter circuit. Based on the observed topological constraint of switched-capacitor converter circuits, the simplest lossless topology for AC/DC conversion is deduced. Also discussed is a simple version of lossless topology that achieves isolation between the source and the load. Finally, an experimental AC/DC switched-capacitor converter, based on the proposed idea, is presented which demonstrates an improved efficiency over other existing switched-capacitor converters. The proposed AC/DC converter contains no inductors and thus is suitable for custom IC implementation for very low power applications.

  16. Nonaqueous Electrolyte Development for Electrochemical Capacitors

    SciTech Connect

    K. Xu; S. P. Ding; T. R. Jow

    1999-09-01

    The objectives of this project were to demonstrate and develop new nonaqueous electrolytes that enable the development of high power (in excess of 2 kW/kg) and high energy (in excess of 8 Wh/kg) capacitors. Electrochemical capacitors are attractive to use because of their long cycle life and inherent high-power (or fast charge/discharge) capabilities. To realize the inherent high-power nature of the capacitor, the resistance of the capacitor needs to be low. The main focus of this project is on the ionic part of capacitor resistance, which is largely determined by the electrolyte, especially the electrolyte's conductivity. To achieve the objectives of this project, two approaches were used. The first was to search for the proper solvent mixtures within the commercially available quaternary ammonium salts such as tetraethyl ammonium tetrafluoroborate (Et4NBF4) or tetraethyl ammonium hexafluorophosphate (Et4NPF6). The second approach was to use the commonly available solvent system s but develop new salts. Substantial advances were made in quaternary ammonium salts and solvent systems were identified that can withstand high voltage operations. However, improvement in the salt alone is not sufficient. Improvements in the low-temperature stability of a capacitor rely not only on the salts but also on the solvents. Likewise, the high-temperature stability of the capacitor will depend not only on the salts but also on the solvents and carbon electrode materials.

  17. Multilevel techniques for nonelliptic problems

    NASA Technical Reports Server (NTRS)

    Jespersen, D. C.

    1981-01-01

    Multigrid and multilevel methods are extended to the solution of nonelliptic problems. A framework for analyzing these methods is established. A simple nonelliptic problem is given, and it is shown how a multilevel technique can be used for its solution. Emphasis is on smoothness properties of eigenvectors and attention is drawn to the possibility of conditioning the eigensystem so that eigenvectors have the desired smoothness properties.

  18. Flying qualities research challenges

    NASA Technical Reports Server (NTRS)

    Sliwa, Steven M.; George, Frank L.

    1987-01-01

    Traditional flying qualities requirements for airplane dynamics are based on airplane modal response characteristics derived from linear small-perturbation analysis. These requirements are supported by a large experimental data base. The challenge to the flying qualities community is to demonstrate how flying qualities, the control system and aircraft configuration are still closely linked. This is evident in the definition of flying qualities and, as far as pilots are concerned, that flying qualities are still the measure of overall design success.

  19. Cantilever and capacitor technique for measuring dilatation

    SciTech Connect

    Primak, W.; Monahan, E.

    1983-05-01

    The relationship of EerNisse's technique for measuring small dilatations caused by irradiation with short-range particles, which utilizes a metallized thin plate mounted as a cantilever below whose free end an electrode is placed (forming a capacitor), to a photoelastic technique and to an interferometric technique are derived. The effects of stray capacitance, the fringing field of the capacitor, the clamping stress on the cantilever plate, the electrical resistance of the metallic coating, the charging of the tank circuit of which the capacitor is an element, the flange bolting stress, and the beam heating are assessed, and examples of the manner in which they contaminate the data are given.

  20. Alkaline Capacitors Based on Nitride Nanoparticles

    NASA Technical Reports Server (NTRS)

    Aldissi, Matt

    2003-01-01

    High-energy-density alkaline electrochemical capacitors based on electrodes made of transition-metal nitride nanoparticles are undergoing development. Transition- metal nitrides (in particular, Fe3N and TiN) offer a desirable combination of high electrical conductivity and electrochemical stability in aqueous alkaline electrolytes like KOH. The high energy densities of these capacitors are attributable mainly to their high capacitance densities, which, in turn, are attributable mainly to the large specific surface areas of the electrode nanoparticles. Capacitors of this type could be useful as energy-storage components in such diverse equipment as digital communication systems, implanted medical devices, computers, portable consumer electronic devices, and electric vehicles.

  1. High Temperature Evaluation of Tantalum Capacitors - Test 1

    DOE Data Explorer

    Cieslewski, Grzegorz

    2014-09-28

    Tantalum capacitors can provide much higher capacitance at high-temperatures than the ceramic capacitors. This study evaluates selected tantalum capacitors at high temperatures to determine their suitability for you in geothermal field. This data set contains results of the first test where three different types of capacitors were evaluated at 260C.

  2. Effects of severe stressing on tantalum capacitors

    NASA Technical Reports Server (NTRS)

    Shakar, J. F.; Fairfield, E. H.

    1981-01-01

    The ultimate capabilities of an all tantalum capacitor were determined and evaluated. The evaluation included: 175 C life; 100 cycle thermal shock; 70 g random vibration; 3000 g shock; and 90 C ase ripple current.

  3. Fabrication and Testing of Polyvinylidene Fluoride Capacitors

    NASA Technical Reports Server (NTRS)

    Buritz, R. S.

    1980-01-01

    High energy density capacitors made from metallized polyvinylidene fluoride film were built and tested. Terminations of aluminum-babbitt, tin-babbitt, and all-babbitt were evaluated. All-babbit terminations appeared to be better. The 0.1 microfarad and 2 microfarad capacitors were made of 6 micrometer material. Capacitance, dissipation factor, and insulation resistance measurements were made over the ranges -55 C to 125 C and 10 Hz to 100 kHz. Twelve of forty-one 0.1 microfarad capacitors survived a 5000 hour dc plus ac life test. Under the same conditions, the 2 microfarad capacitors exhibited overheating because of excessive power loss. Some failures occurred after low temperature exposures for 48 hours. No failures were caused by vibration or temperature cycling.

  4. Automated Test Stand for HEV Capacitor Testing

    SciTech Connect

    Seiber, Larry Eugene; Armstrong, Gary

    2007-01-01

    As capacitor manufacturers race to meet the needs of the hybrid-electric vehicle (HEV) of the future, many trade-offs at the system level as well as the component level must be considered. Even though the ultra-capacitor has the spot light for recent research and development (R&D) for HEVs, the electrostatic capacitor is also the subject of R&D (for HEVs as well as wireless communications). The Department of Energy has funded the Oak Ridge National Laboratory's Power Electronic and Electric Machinery Research Center to develop an automated test to aid in the independent testing of prototype electrostatic capacitors. This paper describes the design and development of such a stand.

  5. Review of the NASA Voyager spacecraft polycarbonate capacitor failure incident

    NASA Technical Reports Server (NTRS)

    Ott, F. M.; Yen, S. P. S.; Somoano, R. B.

    1985-01-01

    The premission failure of a Voyager spacecraft capacitor has prompted an investigation into the use of polycarbonate capacitors in high impedance circuits, during which capacitor failures were induced by thermal cycling together with extended periods at high temperature. Measurement of leakage path temperature coefficients indicates that there are two distinct leakage types whose mechanisms are complicated by movement within the capacitor during temperature changes. A novel system for pulse detection during capacitor burn-in and ramp testing has proven to be beneficial.

  6. Physical and Electrical Characterization of Aluminum Polymer Capacitors

    NASA Technical Reports Server (NTRS)

    Liu, David; Sampson, Michael J.

    2010-01-01

    Polymer aluminum capacitors from several manufacturers with various combinations of capacitance, rated voltage, and ESR values were physically examined and electrically characterized. The physical construction analysis of the capacitors revealed three different capacitor structures, i.e., traditional wound, stacked, and laminated. Electrical characterization results of polymer aluminum capacitors are reported for frequency-domain dielectric response at various temperatures, surge breakdown voltage, and other dielectric properties. The structure-property relations in polymer aluminum capacitors are discussed.

  7. Physical and Electrical Characterization of Polymer Aluminum Capacitors

    NASA Technical Reports Server (NTRS)

    Liu, David; Sampson, Michael J.

    2010-01-01

    Polymer aluminum capacitors from several manufacturers with various combinations of capacitance, rated voltage, and ESR values were physically examined and electrically characterized. The physical construction analysis of the capacitors revealed three different capacitor structures, i.e., traditional wound, stacked, and laminated. Electrical characterization results of polymer aluminum capacitors are reported for frequency-domain dielectric response at various temperatures, surge breakdown voltage, and other dielectric properties. The structure-property relations in polymer aluminum capacitors are discussed.

  8. Anisotropic magnetocapacitance in ferromagnetic-plate capacitors

    NASA Astrophysics Data System (ADS)

    Haigh, J. A.; Ciccarelli, C.; Betz, A. C.; Irvine, A.; Novák, V.; Jungwirth, T.; Wunderlich, J.

    2015-04-01

    The capacitance of a parallel-plate capacitor can depend on the applied magnetic field. Previous studies have identified capacitance changes induced via classical Lorentz force or spin-dependent Zeeman effects. Here we measure a magnetization direction-dependent capacitance in parallel-plate capacitors where one plate is a ferromagnetic semiconductor, gallium manganese arsenide. This anisotropic magnetocapacitance is due to the anisotropy in the density of states dependent on the magnetization through the strong spin-orbit interaction.

  9. Cellulose triacetate, thin film dielectric capacitor

    NASA Technical Reports Server (NTRS)

    Yen, Shiao-Ping S. (Inventor); Jow, T. Richard (Inventor)

    1995-01-01

    Very thin films of cellulose triacetate are cast from a solution containing a small amount of high boiling temperature, non-solvent which evaporates last and lifts the film from the casting surface. Stretched, oriented, crystallized films have high electrical breakdown properties. Metallized films less than about 2 microns in thickness form self-healing electrodes for high energy density, pulsed power capacitors. Thicker films can be utilized as a dielectric for a capacitor.

  10. Cellulose triacetate, thin film dielectric capacitor

    NASA Technical Reports Server (NTRS)

    Yen, Shiao-Ping S. (Inventor); Jow, T. Richard (Inventor)

    1993-01-01

    Very thin films of cellulose triacetate are cast from a solution containing a small amount of high boiling temperature, non-solvent which evaporates last and lifts the film from the casting surface. Stretched, oriented, crystallized films have high electrical breakdown properties. Metallized films less than about 2 microns in thickness form self-healing electrodes for high energy density, pulsed power capacitors. Thicker films can be utilized as a dielectric for a capacitor.

  11. Monolithic ceramic capacitors for high reliability applications

    NASA Technical Reports Server (NTRS)

    Thornley, E. B.

    1981-01-01

    Monolithic multi-layer ceramic dielectric capacitors are widely used in high reliability applications in spacecraft, launch vehicles, and military equipment. Their relatively low cost, wide range of values, and package styles are attractive features that result in high usage in electronic circuitry in these applications. Design and construction of monolithic ceramic dielectric capacitors, defects that can lead to failure, and methods for defect detection that are being incorporated in military specifications are discussed.

  12. Multilevel turbulence simulations

    SciTech Connect

    Tziperman, E.

    1994-12-31

    The authors propose a novel method for the simulation of turbulent flows, that is motivated by and based on the Multigrid (MG) formalism. The method, called Multilevel Turbulence Simulations (MTS), is potentially more efficient and more accurate than LES. In many physical problems one is interested in the effects of the small scales on the larger ones, or in a typical realization of the flow, and not in the detailed time history of each small scale feature. MTS takes advantage of the fact that the detailed simulation of small scales is not needed at all times, in order to make the calculation significantly more efficient, while accurately accounting for the effects of the small scales on the larger scale of interest. In MTS, models of several resolutions are used to represent the turbulent flow. The model equations in each coarse level incorporate a closure term roughly corresponding to the tau correction in the MG formalism that accounts for the effects of the unresolvable scales on that grid. The finer resolution grids are used only a small portion of the simulation time in order to evaluate the closure terms for the coarser grids, while the coarse resolution grids are then used to accurately and efficiently calculate the evolution of the larger scales. The methods efficiency relative to direct simulations is of the order of the ratio of required integration time to the smallest eddies turnover time, potentially resulting in orders of magnitude improvement for a large class of turbulence problems.

  13. Multilevel fusion exploitation

    NASA Astrophysics Data System (ADS)

    Lindberg, Perry C.; Dasarathy, Belur V.; McCullough, Claire L.

    1996-06-01

    This paper describes a project that was sponsored by the U.S. Army Space and Strategic Defense Command (USASSDC) to develop, test, and demonstrate sensor fusion algorithms for target recognition. The purpose of the project was to exploit the use of sensor fusion at all levels (signal, feature, and decision levels) and all combinations to improve target recognition capability against tactical ballistic missile (TBM) targets. These algorithms were trained with simulated radar signatures to accurately recognize selected TBM targets. The simulated signatures represent measurements made by two radars (S-band and X- band) with the targets at a variety of aspect and roll angles. Two tests were conducted: one with simulated signatures collected at angles different from those in the training database and one using actual test data. The test results demonstrate a high degree of recognition accuracy. This paper describes the training and testing techniques used; shows the fusion strategy employed; and illustrates the advantages of exploiting multi-level fusion.

  14. Capacitor blocks for linear transformer driver stages.

    PubMed

    Kovalchuk, B M; Kharlov, A V; Kumpyak, E V; Smorudov, G V; Zherlitsyn, A A

    2014-01-01

    In the Linear Transformer Driver (LTD) technology, the low inductance energy storage components and switches are directly incorporated into the individual cavities (named stages) to generate a fast output voltage pulse, which is added along a vacuum coaxial line like in an inductive voltage adder. LTD stages with air insulation were recently developed, where air is used both as insulation in a primary side of the stages and as working gas in the LTD spark gap switches. A custom designed unit, referred to as a capacitor block, was developed for use as a main structural element of the transformer stages. The capacitor block incorporates two capacitors GA 35426 (40 nF, 100 kV) and multichannel multigap gas switch. Several modifications of the capacitor blocks were developed and tested on the life time and self breakdown probability. Blocks were tested both as separate units and in an assembly of capacitive module, consisting of five capacitor blocks. This paper presents detailed design of capacitor blocks, description of operation regimes, numerical simulation of electric field in the switches, and test results. PMID:24517759

  15. Experimental electrochemical capacitor test results

    SciTech Connect

    Wright, R.B.; Murphy, T.C.; Rogers, S.A.; Sutula, R.A.

    1998-07-01

    Various electrochemical capacitors (ultracapacitors) are being developed for hybrid vehicles as candidate power assist devices for the Partnership for a New Generation of Vehicles (PNGV) fast-response engine. The envisioned primary functions of the ultracapacitor are to level the dynamic power loads on the primary propulsion device and recover available energy from regenerative breaking during off-peak power periods. This paper will present test data from selected US Department of Energy (DOE) supported ultracapacitor projects designed to meet the fast response engine requirements. This paper will address the temperature dependence of test data obtained from a set of three devices provided from Maxwell Energy Products, Inc. These devices are rated at 2,300 F at 2.3 V. Constant-current, constant-power, and self-discharge testing as a function of temperature have been conducted. From these tests were determined the capacitance, equivalent series resistance, specific energy and power, and the self-discharge energy loss factor as a function of the device operating temperature.

  16. Development of advanced polymer nanocomposite capacitors

    NASA Astrophysics Data System (ADS)

    Mendoza, Miguel

    The current development of modern electronics has driven the need for new series of energy storage devices with higher energy density and faster charge/discharge rate. Batteries and capacitors are two of the most widely used energy storage devices. Compared with batteries, capacitors have higher power density and significant higher charge/discharge rate. Therefore, high energy density capacitors play a significant role in modern electronic devices, power applications, space flight technologies, hybrid electric vehicles, portable defibrillators, and pulse power applications. Dielectric film capacitors represent an exceptional alternative for developing high energy density capacitors due to their high dielectric constants, outstanding breakdown voltages, and flexibility. The implementation of high aspect ratio dielectric inclusions such as nanowires into polymer capacitors could lead to further enhancement of its energy density. Therefore, this research effort is focused on the development of a new series of dielectric capacitors composed of nanowire reinforced polymer matrix composites. This concept of nanocomposite capacitors combines the extraordinary physical and chemical properties of the one-dimension (1D) nanoceramics and high dielectric strength of polymer matrices, leading to a capacitor with improved dielectric properties and energy density. Lead-free sodium niobate (NaNbO3) and lead-containing lead magnesium niobate-lead titanate (0.65PMN-0.35PT) nanowires were synthesized following hydrothermal and sol-gel approaches, respectively. The as-prepared nanowires were mixed with a polyvinylidene fluoride (PVDF) matrix using solution-casting method for nanocomposites fabrication. The dielectric constants and breakdown voltages of the NaNbO3/PVDF and 0.65PMN-0.35PT/PVDF nanocomposites were measured under different frequency ranges and temperatures in order to determine their maximum energy (J/cm3) and specific (J/g) densities. The electrical properties of the

  17. A Five-Level Three-Phase Cascade Multilevel Inverter Using a Single DC Source for a PM Synchronous Motor Drive

    SciTech Connect

    Ozpineci, Burak; Chiasson, John N; Tolbert, Leon M

    2007-01-01

    The interest here is in using a single DC power source to construct a 3-phase 5-level cascade multilevel inverter to be used as a drive for a PM traction motor. The 5-level inverter consists of a standard 3-leg inverter (one leg for each phase) and an H-bridge in series with each inverter leg, which use a capacitor as a DC source. It is shown that one can simultaneously maintain the regulation of the capacitor voltage while achieving an output voltage waveform which is 25% higher than that obtained using a standard 3-leg inverter by itself.

  18. Titanium-Alloy Power Capacitor: High-Power Titanate Capacitor for Power Electronics

    SciTech Connect

    2010-09-01

    ADEPT Project: There is a constant demand for better performing, more compact, lighter weight, and lower cost electronic devices. Unfortunately, the materials traditionally used to make components for electronic devices have reached their limits. Case Western is developing capacitors made of new materials that could be used to produce the next generation of compact and efficient high-powered consumer electronics and electronic vehicles. A capacitor is an important component of an electronic device. It stores an electric charge and then discharges it into an electrical circuit in the device. Case Western is creating its capacitors from titanium, an abundant material extracted from ore which can be found in the U.S. Case Western's capacitors store electric charges on the surfaces of films, which are grown on a titanium alloy electrode that is formed as a spinal column with attached branches. The new material and spine design make the capacitor smaller and lighter than traditional capacitors, and they enable the component to store 300% more energy than capacitors of the same weight made of tantalum, the current industry standard. Case Western's titanium-alloy capacitors also spontaneously self-repair, which prolongs their life.

  19. Stable Fly Research

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Adult stable flies feed on the blood of humans, pets and livestock, inflicting painful bites. Stable flies need one and sometimes two bloodmeals each day to develop their eggs. Unlike mosquitoes where only the females bloodfeed, both male and female stable flies require blood to reproduce. Stable fl...

  20. Multilevel codes and multistage decoding

    NASA Astrophysics Data System (ADS)

    Calderbank, A. R.

    1989-03-01

    Imai and Hirakawa have proposed (1977) a multilevel coding method based on binary block codes that admits a staged decoding procedure. Here the coding method is extended to coset codes and it is shown how to calculate minimum squared distance and path multiplicity in terms of the norms and multiplicities of the different cosets. The multilevel structure allows the redundancy in the coset selection procedure to be allocated efficiently among the different levels. It also allows the use of suboptimal multistage decoding procedures that have performance/complexity advantages over maximum-likelihood decoding.

  1. Multilevel Ensemble Transform Particle Filtering

    NASA Astrophysics Data System (ADS)

    Gregory, Alastair; Cotter, Colin; Reich, Sebastian

    2016-04-01

    This presentation extends the Multilevel Monte Carlo variance reduction technique to nonlinear filtering. In particular, Multilevel Monte Carlo is applied to a certain variant of the particle filter, the Ensemble Transform Particle Filter (ETPF). A key aspect is the use of optimal transport methods to re-establish correlation between coarse and fine ensembles after resampling; this controls the variance of the estimator. Numerical examples present a proof of concept of the effectiveness of the proposed method, demonstrating significant computational cost reductions (relative to the single-level ETPF counterpart) in the propagation of ensembles.

  2. A General Multilevel SEM Framework for Assessing Multilevel Mediation

    ERIC Educational Resources Information Center

    Preacher, Kristopher J.; Zyphur, Michael J.; Zhang, Zhen

    2010-01-01

    Several methods for testing mediation hypotheses with 2-level nested data have been proposed by researchers using a multilevel modeling (MLM) paradigm. However, these MLM approaches do not accommodate mediation pathways with Level-2 outcomes and may produce conflated estimates of between- and within-level components of indirect effects. Moreover,…

  3. High-Temperature Capacitor Polymer Films

    NASA Astrophysics Data System (ADS)

    Tan, Daniel; Zhang, Lili; Chen, Qin; Irwin, Patricia

    2014-12-01

    Film capacitor technology has been under development for over half a century to meet various applications such as direct-current link capacitors for transportation, converters/inverters for power electronics, controls for deep well drilling of oil and gas, direct energy weapons for military use, and high-frequency coupling circuitry. The biaxially oriented polypropylene film capacitor remains the state-of-the-art technology; however, it is not able to meet increasing demand for high-temperature (>125°C) applications. A number of dielectric materials capable of operating at high temperatures (>140°C) have attracted investigation, and their modifications are being pursued to achieve higher volumetric efficiency as well. This paper highlights the status of polymer dielectric film development and its feasibility for capacitor applications. High-temperature polymers such as polyetherimide (PEI), polyimide, and polyetheretherketone were the focus of our studies. PEI film was found to be the preferred choice for high-temperature film capacitor development due to its thermal stability, dielectric properties, and scalability.

  4. BioCapacitor--a novel category of biosensor.

    PubMed

    Hanashi, Takuya; Yamazaki, Tomohiko; Tsugawa, Wakako; Ferri, Stefano; Nakayama, Daisuke; Tomiyama, Masamitsu; Ikebukuro, Kazunori; Sode, Koji

    2009-03-15

    This research reports on the development of an innovative biosensor, known as BioCapacitor, in which biological recognition elements are combined with a capacitor functioning as the transducer. The analytical procedure of the BioCapacitor is based on the following principle: a biocatalyst, acting as a biological recognition element, oxidizes or reduces the analyte to generate electric power, which is then charged into a capacitor via a charge pump circuit (switched capacitor regulator) until the capacitors attains full capacity. Since the charging rate of the capacitor depends on the biocatalytic reaction of the analyte, the analyte concentration can be determined by monitoring the time/frequency required for the charge/discharge cycle of the BioCapacitor via a charge pump circuit. As a representative model, we constructed a BioCapacitor composed of FAD-dependent glucose dehydrogenase (FADGDH) as the anodic catalyst, and attempted a glucose measurement. Charge/discharge frequency of the BioCapacitor increased with the increasing glucose concentration, exhibiting good correlation with glucose concentration. We have also constructed a wireless sensing system using the BioCapacitor combined with an infrared light emitting diode (IRLED), an IR phototransistor system. In the presence of glucose, the IRLED signal was observed due to the discharge of the BioCapacitor and detected by an IR phototransistor in a wireless receiver. Therefore, a BioCapacitor employing FADGDH as its anodic catalyst can be operated as a self-powered enzyme sensor. PMID:19013784

  5. Multilevel Modeling with Correlated Effects

    ERIC Educational Resources Information Center

    Kim, Jee-Seon; Frees, Edward W.

    2007-01-01

    When there exist omitted effects, measurement error, and/or simultaneity in multilevel models, explanatory variables may be correlated with random components, and standard estimation methods do not provide consistent estimates of model parameters. This paper introduces estimators that are consistent under such conditions. By employing generalized…

  6. Generalized Multilevel Structural Equation Modeling

    ERIC Educational Resources Information Center

    Rabe-Hesketh, Sophia; Skrondal, Anders; Pickles, Andrew

    2004-01-01

    A unifying framework for generalized multilevel structural equation modeling is introduced. The models in the framework, called generalized linear latent and mixed models (GLLAMM), combine features of generalized linear mixed models (GLMM) and structural equation models (SEM) and consist of a response model and a structural model for the latent…

  7. Multilevel algorithms for nonlinear optimization

    NASA Technical Reports Server (NTRS)

    Alexandrov, Natalia; Dennis, J. E., Jr.

    1994-01-01

    Multidisciplinary design optimization (MDO) gives rise to nonlinear optimization problems characterized by a large number of constraints that naturally occur in blocks. We propose a class of multilevel optimization methods motivated by the structure and number of constraints and by the expense of the derivative computations for MDO. The algorithms are an extension to the nonlinear programming problem of the successful class of local Brown-Brent algorithms for nonlinear equations. Our extensions allow the user to partition constraints into arbitrary blocks to fit the application, and they separately process each block and the objective function, restricted to certain subspaces. The methods use trust regions as a globalization strategy, and they have been shown to be globally convergent under reasonable assumptions. The multilevel algorithms can be applied to all classes of MDO formulations. Multilevel algorithms for solving nonlinear systems of equations are a special case of the multilevel optimization methods. In this case, they can be viewed as a trust-region globalization of the Brown-Brent class.

  8. High-current, high-frequency capacitors

    NASA Technical Reports Server (NTRS)

    Renz, D. D.

    1983-01-01

    The NASA Lewis high-current, high-frequency capacitor development program was conducted under a contract with Maxwell Laboratories, Inc., San Diego, California. The program was started to develop power components for space power systems. One of the components lacking was a high-power, high-frequency capacitor. Some of the technology developed in this program may be directly usable in an all-electric airplane. The materials used in the capacitor included the following: the film is polypropylene, the impregnant is monoisopropyl biphenyl, the conductive epoxy is Emerson and Cuming Stycast 2850 KT, the foil is aluminum, the case is stainless steel (304), and the electrode is a modified copper-ceramic.

  9. Downhole transmission system comprising a coaxial capacitor

    DOEpatents

    Hall, David R.; Pixton, David S.; Johnson, Monte L.; Bartholomew, David B.; Hall, Jr., H. Tracy; Rawle, Michael

    2011-05-24

    A transmission system in a downhole component comprises a plurality of data transmission elements. A coaxial cable having an inner conductor and an outer conductor is disposed within a passage in the downhole component such that at least one capacitor is disposed in the passage and having a first terminal coupled to the inner conductor and a second terminal coupled to the outer conductor. Preferably the transmission element comprises an electrically conducting coil. Preferably, within the passage a connector is adapted to electrically connect the inner conductor of the coaxial cable and the lead wire. The coaxial capacitor may be disposed between and in electrically communication with the connector and the passage. In another embodiment a connector is adapted to electrical connect a first and a second portion of the inner conductor of the coaxial cable and a coaxial capacitor is in electrical communication with the connector and the passage.

  10. Cylindrical Asymmetrical Capacitor Devices for Space Applications

    NASA Technical Reports Server (NTRS)

    Campbell, Jonathan W. (Inventor)

    2004-01-01

    An asymmetrical capacitor system is provided which creates a thrust force. The system is adapted for use in space applications and includes a capacitor device provided with a first conductive element and a second conductive element axially spaced from the first conductive element and of smaller axial extent. A shroud supplied with gas surrounds the capacitor device. The second conductive element can be a wire ring or mesh mounted on dielectric support posts affixed to a dielectric member which separates the conductive elements or a wire or mesh annulus surrounding a barrel-shaped dielectric member on which the h t element is also mounted. A high voltage source is connected across the conductive elements and applies a high voltage to the conductive elements of sufficient value to create a thrust force on the system inducing movement thereof.

  11. Internal fuse modules for solid tantalum capacitors

    NASA Technical Reports Server (NTRS)

    Dematos, H. V.

    1981-01-01

    Miniature fuse modules were designed for and incorporated into two styles of solid tantalum capacitors. One is an epoxy molded, radial leaded, high frequency decoupling capacitor; the other is an hermetically sealed device with axial lead wires. The fusible element for both devices consists of a fine bimetallic wire which reacts exothermically upon reaching a critical temperature and then disintegrates. The desirability of having fused devices is discussed and design constraints, in particular those which minimize inductance and series resistance while optimizing fuse actuation characteristics, are reviewed. Factors affecting the amount of energy required to actuate the fuse and reliability of acuation are identified.

  12. Electron waiting times for the mesoscopic capacitor

    NASA Astrophysics Data System (ADS)

    Hofer, Patrick P.; Dasenbrook, David; Flindt, Christian

    2016-08-01

    We evaluate the distribution of waiting times between electrons emitted by a driven mesoscopic capacitor. Based on a wave packet approach we obtain analytic expressions for the electronic waiting time distribution and the joint distribution of subsequent waiting times. These semi-classical results are compared to a full quantum treatment based on Floquet scattering theory and good agreement is found in the appropriate parameter ranges. Our results provide an intuitive picture of the electronic emissions from the driven mesoscopic capacitor and may be tested in future experiments.

  13. Capacitors: operating principles, current market and technical trends

    NASA Astrophysics Data System (ADS)

    Nishino, Atsushi

    The worldwide market for capacitors was approximately US$ 12.3 billion in 1993, of which production within Japan accounted for approximately 50% and the combined domestic and overseas production of Japanese manufacturers accounted for approximately 70%. The worldwide capacitor market continues to grow by approximately 20% per year as the demand for ICs and LSIs is growing. In conjunction with this special issue on capacitors, this paper presents a corporate perspective on current trends in the capacitor market: capacitor principles; capacitor materials; capacitor types and major characteristics; recent technical trends in capacitors and the future market outlook, and technical problems in the hope of facilitating the understanding of ideas and concepts presented in other papers in this issue.

  14. Large capacitor performs as a distributed parameter pulse line

    NASA Technical Reports Server (NTRS)

    Gooding, T. J.

    1966-01-01

    Capacitor of extended foil construction performs as a distributed parameter pulse line in which current, amplitude, and period are readily controlled. The capacitor is used as the energy storage element in a pulsed plasma accelerator.

  15. Fly ash carbon passivation

    DOEpatents

    La Count, Robert B; Baltrus, John P; Kern, Douglas G

    2013-05-14

    A thermal method to passivate the carbon and/or other components in fly ash significantly decreases adsorption. The passivated carbon remains in the fly ash. Heating the fly ash to about 500 and 800 degrees C. under inert gas conditions sharply decreases the amount of surfactant adsorbed by the fly ash recovered after thermal treatment despite the fact that the carbon content remains in the fly ash. Using oxygen and inert gas mixtures, the present invention shows that a thermal treatment to about 500 degrees C. also sharply decreases the surfactant adsorption of the recovered fly ash even though most of the carbon remains intact. Also, thermal treatment to about 800 degrees C. under these same oxidative conditions shows a sharp decrease in surfactant adsorption of the recovered fly ash due to the fact that the carbon has been removed. This experiment simulates the various "carbon burnout" methods and is not a claim in this method. The present invention provides a thermal method of deactivating high carbon fly ash toward adsorption of AEAs while retaining the fly ash carbon. The fly ash can be used, for example, as a partial Portland cement replacement in air-entrained concrete, in conductive and other concretes, and for other applications.

  16. The Application of Perfluorocarbons as Impregnants for Plastic Film Capacitors

    NASA Technical Reports Server (NTRS)

    Mauldin, G. H.

    1981-01-01

    A liquid impregnated, plastic film (wet) capacitor was developed that is thought to be the most reliable and space efficient capacitor of any type ever produced for high voltage, pulse discharge service. The initial design stores five times the energy of a premium quality dry capacitor of equivalent energy and reliability. The technology, as well as a production capacitor design using this technology are described.

  17. Iodine encapsulation in CNTs and its application for electrochemical capacitor

    NASA Astrophysics Data System (ADS)

    Taniguchi, Y.; Ishii, Y.; Rashid, M.; Syakirin, A.; Al-zubaidi, A.; Kawasaki, S.

    2016-07-01

    We report the experimental results for new type electrochemical capacitor using iodine redox reaction in single-walled carbon nanotubes (SWCNTs). It was found that the energy density of the present redox capacitor using SWCNTs is almost three times larger than that of the normal electric double layer capacitor.

  18. Two Theorems on Dissipative Energy Losses in Capacitor Systems

    ERIC Educational Resources Information Center

    Newburgh, Ronald

    2005-01-01

    This article examines energy losses in charge motion in two capacitor systems. In the first charge is transferred from a charged capacitor to an uncharged one through a resistor. In the second a battery charges an originally uncharged capacitor through a resistance. Analysis leads to two surprising general theorems. In the first case the fraction…

  19. Dynamics of a Liquid Dielectric Attracted by a Cylindrical Capacitor

    ERIC Educational Resources Information Center

    Nardi, Rafael; Lemos, Nivaldo A.

    2007-01-01

    The dynamics of a liquid dielectric attracted by a vertical cylindrical capacitor are studied. Contrary to what might be expected from the standard calculation of the force exerted by the capacitor, the motion of the dielectric is different depending on whether the charge or the voltage of the capacitor is held constant. The problem turns out to…

  20. Scintillation Breakdowns in Chip Tantalum Capacitors

    NASA Technical Reports Server (NTRS)

    Teverovsky, Alexander

    2008-01-01

    Scintillations in solid tantalum capacitors are momentarily local breakdowns terminated by a self-healing or conversion to a high-resistive state of the manganese oxide cathode. This conversion effectively caps the defective area of the tantalum pentoxide dielectric and prevents short-circuit failures. Typically, this type of breakdown has no immediate catastrophic consequences and is often considered as nuisance rather than a failure. Scintillation breakdowns likely do not affect failures of parts under surge current conditions, and so-called "proofing" of tantalum chip capacitors, which is a controllable exposure of the part after soldering to voltages slightly higher than the operating voltage to verify that possible scintillations are self-healed, has been shown to improve the quality of the parts. However, no in-depth studies of the effect of scintillations on reliability of tantalum capacitors have been performed so far. KEMET is using scintillation breakdown testing as a tool for assessing process improvements and to compare quality of different manufacturing lots. Nevertheless, the relationship between failures and scintillation breakdowns is not clear, and this test is not considered as suitable for lot acceptance testing. In this work, scintillation breakdowns in different military-graded and commercial tantalum capacitors were characterized and related to the rated voltages and to life test failures. A model for assessment of times to failure, based on distributions of breakdown voltages, and accelerating factors of life testing are discussed.

  1. Capacitor discharge process for welding braided cable

    DOEpatents

    Wilson, Rick D.

    1995-01-01

    A capacitor discharge process for welding a braided cable formed from a plurality of individual cable strands to a solid metallic electrically conductive member comprises the steps of: (a) preparing the electrically conductive member for welding by bevelling one of its end portions while leaving an ignition projection extending outwardly from the apex of the bevel; (b) clamping the electrically conductive member in a cathode fixture; (c) connecting the electrically conductive member clamped in the cathode fixture to a capacitor bank capable of being charged to a preselected voltage value; (d) preparing the braided cable for welding by wrapping one of its end portions with a metallic sheet to form a retaining ring operable to maintain the individual strands of the braided cable in fixed position within the retaining ring; (e) clamping the braided cable and the retaining ring as a unit in an anode fixture so that the wrapped end portion of the braided cable faces the ignition projection of the electrically conductive member; and (f) moving the cathode fixture towards the anode fixture until the ignition projection of the electrically conductive member contacts the end portion of the braided cable thereby allowing the capacitor bank to discharge through the electrically conductive member and through the braided cable and causing the electrically conductive member to be welded to the braided cable via capacitor discharge action.

  2. Coaxial capacitor used to determine fluid density

    NASA Technical Reports Server (NTRS)

    Atkisson, E. A.

    1965-01-01

    Sensing device measures directly the density of compressible fluid existing simultaneously in both liquid and gaseous phases. The device is comprised of a capacitor connected as one leg of a bridge circuit, a power source, and an indicator calibrated to indicate density as a direct measurement.

  3. Integration of thin film decoupling capacitors

    SciTech Connect

    Garino, T.; Dimos, D.; Lockwood, S.

    1994-10-01

    Thin film decoupling capacitors consisting of submicron thick, sol-gel Pb(Zr,Ti)O{sub 3} layers between Pt electrodes on a Si substrate have recently been developed. Because the capacitor structure needs to be only {approximately}3 {mu}m thick, these devices offer advantages such as decreased package volume and ability to integrate so that interconnect inductance is decreased, which allows faster IC processing rates. To fully utilize these devices, techniques of integrating them onto packages such as multi-chip modules and printed wiring boards or onto IC dies must be developed. The results of our efforts at developing integration processes for these capacitors are described here. Specifically, we have demonstrated a process for printing solder on the devices at the Si wafer level and reflowing it to form bumps and have developed a process for fabricating the devices on thin (25 to 75 {mu}m) substrates to facilitate integration onto ICs and printed wiring boards. Finally, we assessed the feasibility of fabricating the devices on rough surfaces to determine whether it would be possible to fabricate these capacitors directly on multi-layer ceramic substrates.

  4. Negative Capacitance transients in a ferroelectric capacitor

    NASA Astrophysics Data System (ADS)

    Khan, Asif; Chatterjee, Korok; Wang, Brian; Drapcho, Steven; You, Long; Serrao, Claudy; Bakaul, Saidur; Ramesh, Ramamoorthy; Salahuddin, Sayeef

    2015-03-01

    The Boltzmann distribution of electrons poses a fundamental barrier to lowering energy dissipation in conventional electronics, often termed as Boltzmann Tyranny. Negative capacitance in ferroelectric materials, which stems from the stored energy of phase transition, could provide a solution, but a direct measurement of negative capacitance has so far been elusive. Here we demonstrate the negative differential capacitance in a thin, single crystalline ferroelectric film, by constructing a simple R-C network and monitoring the voltage dynamics across the ferroelectric capacitor6. When a voltage pulse is applied, the voltage across the ferroelectric capacitor is found to be decreasing with time-in exactly the opposite direction to which voltage for a regular capacitor should change. The results are analyzed on the basis of the Landau-Khalatnikov equation, which shows that as the ferroelectric polarization switches its direction, it passes through the unstable negative capacitance region resulting in the characteristic ``negative capacitance transients.'' Analysis of this ``inductance''-like behavior from a capacitor allows us to calculate the value of the negative capacitance directly and presents an unprecedented insight into the intrinsic energy profile of the ferroelectric material.

  5. Special Section: Electrochemical capacitors: Guest Editor's note

    NASA Astrophysics Data System (ADS)

    Balducci, Andrea

    2016-09-01

    Electrochemical capacitors (i.e., supercapacitors) are nowadays considered as one of the most important electrochemical storage devices. Thanks to their high power, extraordinary cycle life and high reliability these devices are currently used in a large number of applications, rendering them indispensible for our daily life.

  6. Equal Plate Charges on Series Capacitors?

    ERIC Educational Resources Information Center

    Illman, B. L.; Carlson, G. T.

    1994-01-01

    Provides a line of reasoning in support of the contention that the equal charge proposition is at best an approximation. Shows how the assumption of equal plate charge on capacitors in series contradicts the conservative nature of the electric field. (ZWH)

  7. Capacitors and Resistance-Capacitance Networks.

    ERIC Educational Resources Information Center

    Balabanian, Norman; Root, Augustin A.

    This programed textbook was developed under a contract with the United States Office of Education as Number 5 in a series of materials for use in an electrical engineering sequence. It is divided into three parts--(1) capacitors, (2) voltage-current relationships, and (3) simple resistance-capacitance networks. (DH)

  8. Charge and Energy Stored in a Capacitor

    ERIC Educational Resources Information Center

    Kraftmakher, Yaakov

    2012-01-01

    Using a data-acquisition system, the charge and energy stored in a capacitor are measured and displayed during the charging/discharging process. The experiment is usable as a laboratory work and/or a lecture demonstration. (Contains 3 figures.)

  9. Capacitors, Water Bottles, and Kirchoff's Loop Rule.

    ERIC Educational Resources Information Center

    Newburgh, R. G.

    1993-01-01

    Presents an analogy between electrical potential and potential energy per unit mass. The analogy is used to solve the problem of calculating the final charges of two capacitors after they are connected and to help students understand the concept of electrical potential. (MDH)

  10. Extended foil capacitor with radially spoked electrodes

    DOEpatents

    Foster, James C.

    1990-01-01

    An extended foil capacitor has a conductive disk electrically connected in oncrushing contact to the extended foil. A conductive paste is placed through spaces between radial spokes on the disk to electrically and mechanically connect the extended foil to the disk.

  11. Pseudo-capacitor device for aqueous electrolytes

    DOEpatents

    Prakash, J.; Thackeray, M.M.; Dees, D.W.; Vissers, D.R.; Myles, K.M.

    1998-11-24

    A pseudo-capacitor having a high energy storage capacity develops a double layer capacitance as well as a Faradaic or battery-like redox reaction, also referred to as pseudo-capacitance. The Faradaic reaction gives rise to a capacitance much greater than that of the typical ruthenate oxide ultracapacitor which develops only charge separation-based double layer capacitance. The capacitor employs a lead and/or bismuth/ruthenate and/or iridium system having the formula A{sub 2}[B{sub 2{minus}x}Pb{sub x}]O{sub 7{minus}y}, where A=Pb, Bi, and B=Ru, Ir, and Ocapacitor. The amount of expensive ruthenate and iridium can be substantially reduced in the pseudo-capacitor by increasing the lead content while improving energy storage capacity. 8 figs.

  12. Pseudo-capacitor device for aqueous electrolytes

    DOEpatents

    Prakash, Jai; Thackeray, Michael M.; Dees, Dennis W.; Vissers, Donald R.; Myles, Kevin M.

    1998-01-01

    A pseudo-capacitor having a high energy storage capacity develops a double layer capacitance as well as a Faradaic or battery-like redox reaction, also referred to as pseudo-capacitance. The Faradaic reaction gives rise to a capacitance much greater than that of the typical ruthenate oxide ultracapacitor which develops only charge separation-based double layer capacitance. The capacitor employs a lead and/or bismuth/ruthenate and/or iridium system having the formula A.sub.2 ›B.sub.2-x Pb.sub.x !O.sub.7-y, where A=Pb, Bi, and B=Ru, Ir, and Ocapacitor. The amount of expensive ruthenate and iridium can be substantially reduced in the pseudo-capacitor by increasing the lead content while improving energy storage capacity.

  13. Reliability performance of pulse discharge capacitors

    SciTech Connect

    Edwards, L.R.

    1997-02-01

    There is a void of public specifications for pulse discharge capacitor applications. Sandia National Laboratories has developed, over the past 25 years, specifications and test procedures for evaluating capacitor designs for this specialized use. There are three primary destructive tests that are used to assess the reliability potential of a given design at a required rated voltage. These are ultimate short time breakdown strength, life at voltage, and pulse discharge life. The strategy of the method is to accelerate the test conditions so that failures are observable and then extrapolate to the desired use conditions where the failure rates are low. This paper will present the statistical methodologies employed to analyze experimental data and to provide a point estimate of reliability with a lower confidence bound as a function of rated voltage. In addition, methods for establishing lot-acceptance-criteria specifications will be discussed. The techniques will be illustrated with actual data on a commercially available, low-inductance, pulse-discharge capacitor. The capacitor is an impregnated dual dielectric (mica-paper/polymer film), extended-foil type.

  14. Electrostatic spray deposition based lithium ion capacitor

    NASA Astrophysics Data System (ADS)

    Agrawal, Richa; Chen, Chunhui; Wang, Chunlei

    2016-05-01

    Conventional Electrochemical double-layer capacitors (EDLCs) are well suited as power devices that can provide large bursts of energy in short time periods. However, their relatively inferior energy densities as compared to their secondary battery counterparts limit their application in devices that require simultaneous supply of both high energy and high power. In the wake of addressing this shortcoming of EDLCs, the concept of hybridization of lithium-ion batteries (LIBs) and EDLCs has attracted significant scientific interest in recent years. Such a device, generally referred to as the "lithium-ion capacitor" typically utilizes a lithium intercalating electrode along with a fast charging capacitor electrode. Herein we have constructed a lithium hybrid electrochemical capacitor comprising a Li4Ti5O12-TiO2 (LTO-TiO2) anode and a reduced graphene oxide and carbon nanotube (rGO-CNT) composite cathode using electrostatic spray deposition (ESD). The electrodes were characterized using scanning electron microscopy and X-ray diffraction studies. Cyclic voltammetry and galvanostatic charge-discharge measurements were carried out to evaluate the electrochemical performance of the individual electrodes and the full hybrid cells.

  15. Negative Capacitance in a Ferroelectric Capacitor

    NASA Astrophysics Data System (ADS)

    Khan, Asif; Chatterjee, Korok; Wang, Brian; Drapcho, Steven; You, Long; Serrao, Claudy; Bakaul, Saidur; Ramesh, Ramamoorthy; Salahuddin, Sayeef; UC Berkeley Team

    The Boltzmann distribution of electrons poses a fundamental barrier to lowering energy dissipation in conventional electronics, often termed as Boltzmann Tyranny. Negative capacitance in ferroelectric materials, which stems from the stored energy of phase transition, could provide a solution, but a direct measurement of negative capacitance has so far been elusive. Here we demonstrate the negative differential capacitance in an epitaxial ferroelectric film, by constructing a simple R-C network and monitoring the voltage dynamics across the ferroelectric capacitor. When a voltage pulse is applied, the voltage across the ferroelectric capacitor is found to be decreasing with time-in exactly the opposite direction to which voltage for a regular capacitor should change. The results are analyzed on the basis of the Landau-Khalatnikov equation, which shows that as the ferroelectric polarization switches its direction, it passes through the unstable negative capacitance region. Analysis of this behavior from a capacitor presents an unprecedented insight into the intrinsic energy profile of the ferroelectric material.

  16. Method of making electrolytic capacitor anodes

    SciTech Connect

    Melody, B.; Eickelberg, E.W.

    1987-05-12

    A method is described of making an anode for an electrolytic capacitor. The method comprises providing a powder consisting of a film-forming metal, polyethylene oxide, and ammonium carbonate; pressing the powder to form an anode body; and heating the anode body to remove the polyethylene oxide and ammonium carbonate.

  17. Single-poly EEPROM cell with lightly doped MOS capacitors

    DOEpatents

    Riekels, James E.; Lucking, Thomas B.; Larsen, Bradley J.; Gardner, Gary R.

    2008-05-27

    An Electrically Erasable Programmable Read Only Memory (EEPROM) memory cell and a method of operation are disclosed for creating an EEPROM memory cell in a standard CMOS process. A single polysilicon layer is used in combination with lightly doped MOS capacitors. The lightly doped capacitors employed in the EEPROM memory cell can be asymmetrical in design. Asymmetrical capacitors reduce area. Further capacitance variation caused by inversion can also be reduced by using multiple control capacitors. In addition, the use of multiple tunneling capacitors provides the benefit of customized tunneling paths.

  18. Sound radiation around a flying fly

    NASA Astrophysics Data System (ADS)

    Sueur, Jérôme; Tuck, Elizabeth J.; Robert, Daniel

    2005-07-01

    Many insects produce sounds during flight. These acoustic emissions result from the oscillation of the wings in air. To date, most studies have measured the frequency characteristics of flight sounds, leaving other acoustic characteristics-and their possible biological functions-unexplored. Here, using close-range acoustic recording, we describe both the directional radiation pattern and the detailed frequency composition of the sound produced by a tethered flying (Lucilia sericata). The flapping wings produce a sound wave consisting of a series of harmonics, the first harmonic occurring around 190 Hz. In the horizontal plane of the fly, the first harmonic shows a dipolelike amplitude distribution whereas the second harmonic shows a monopolelike radiation pattern. The first frequency component is dominant in front of the fly while the second harmonic is dominant at the sides. Sound with a broad frequency content, typical of that produced by wind, is also recorded at the back of the fly. This sound qualifies as pseudo-sound and results from the vortices generated during wing kinematics. Frequency and amplitude features may be used by flies in different behavioral contexts such as sexual communication, competitive communication, or navigation within the environment.

  19. A multilevel stochastic collocation method for SPDEs

    SciTech Connect

    Gunzburger, Max; Jantsch, Peter; Teckentrup, Aretha; Webster, Clayton

    2015-03-10

    We present a multilevel stochastic collocation method that, as do multilevel Monte Carlo methods, uses a hierarchy of spatial approximations to reduce the overall computational complexity when solving partial differential equations with random inputs. For approximation in parameter space, a hierarchy of multi-dimensional interpolants of increasing fidelity are used. Rigorous convergence and computational cost estimates for the new multilevel stochastic collocation method are derived and used to demonstrate its advantages compared to standard single-level stochastic collocation approximations as well as multilevel Monte Carlo methods.

  20. High energy density capacitors using nano-structure multilayer technology

    SciTech Connect

    Barbee, T.W. Jr.; Johnson, G.W.; O`Brien, D.W.

    1992-08-01

    Today, many pulse power and industrial applications are limited by capacitor performance. While incremental improvements are anticipated from existing capacitor technologies, significant advances are needed in energy density to enable these applications for both the military and for American economic competitiveness. We propose a program to research and develop a novel technology for making high voltage, high energy density capacitors. Nano-structure multilayer technologies developed at LLNL may well provide a breakthrough in capacitor performance. Our controlled sputtering techniques are capable of laying down extraordinarily smooth sub-micron layers of dielectric and conductor materials. With this technology, high voltage capacitors with an order of magnitude improvement in energy density may be achievable. Well-understood dielectrics and new materials will be investigated for use with this technology. Capacitors developed by nano-structure multilayer technology are inherently solid state, exhibiting extraordinary mechanical and thermal properties. The conceptual design of a Notepad capacitor is discussed to illustrate capacitor and capacitor bank design and performance with this technology. We propose a two phase R&D program to address DNA`s capacitor needs for electro-thermal propulsion and similar pulse power programs. Phase 1 will prove the concept and further our understanding of dielectric materials and design tradeoffs with multilayers. Nano-structure multilayer capacitors will be developed and characterized. As our materials research and modeling prove successful, technology insertion in our capacitor designs will improve the possibility for dramatic performance improvements. In Phase 2, we will make Notepad capacitors, construct a capacitor bank and demonstrate its performance in a meaningful pulse power application. We will work with industrial partners to design full scale manufacturing and move this technology to industry for volume production.

  1. Activation of fly ash

    DOEpatents

    Corbin, David R.; Velenyi, Louis J.; Pepera, Marc A.; Dolhyj, Serge R.

    1986-01-01

    Fly ash is activated by heating a screened magnetic fraction of the ash in a steam atmosphere and then reducing, oxidizing and again reducing the hydrothermally treated fraction. The activated fly ash can be used as a carbon monoxide disproportionating catalyst useful in the production of hydrogen and methane.

  2. Ever Fly a Tetrahedron?

    ERIC Educational Resources Information Center

    King, Kenneth

    2004-01-01

    Few things capture the spirit of spring like flying a kite. Watching a kite dance and sail across a cloud spotted sky is not only a visually appealing experience it also provides a foundation for studies in science and mathematics. Put simply, a kite is an airfoil surface that flies when the forces of lift and thrust are greater than the forces of…

  3. Activation of fly ash

    DOEpatents

    Corbin, D.R.; Velenyi, L.J.; Pepera, M.A.; Dolhyj, S.R.

    1986-08-19

    Fly ash is activated by heating a screened magnetic fraction of the ash in a steam atmosphere and then reducing, oxidizing and again reducing the hydrothermally treated fraction. The activated fly ash can be used as a carbon monoxide disproportionating catalyst useful in the production of hydrogen and methane.

  4. A Flying Summer Camp

    ERIC Educational Resources Information Center

    Mercurio, Frank X.

    1975-01-01

    Describes a five-day summer camp which provided 12 children, ages 9-14, with a complete flying experience. The training consisted of ground school and one hour actual flying time, including the basics of aircraft control and a flight prepared and executed by the students. (MLH)

  5. Non-ideal effects of MOS capacitor in a switched capacitor waveform recorder ASIC

    NASA Astrophysics Data System (ADS)

    Zhang, Hong-Yan; Deng, Zhi; Liu, Yi-Nong

    2016-07-01

    SCAs (Switched Capacitor Arrays) have a wide range of uses, especially in high energy physics, nuclear science and astrophysics experiments. This paper presents a method of using a MOS capacitor as a sampling capacitor to gain larger capacitance with small capacitor area in SCA design. It studies the non-ideal effects of the MOS capacitor and comes up with ways to reduce these adverse effects. A prototype SCA ASIC which uses a MOS capacitor to store the samples has been designed and tested to verify this method. The SCA integrates 32 channels and each has 64 cells and a readout amplifier. The stored voltage is converted to a pair of differential currents (±4 mA max) and multiplexed to the output. All the functionalities have been verified. The power consumption is less than 2 mW/ch. The INL of all the cells in one channel are better than 0.39%. The equivalent input noise of the SCA has been tested to be 2.2 mV with 625 kHz full-scale sine wave as input, sampling at 40 MSPS (Mega-samples per Second) and reading out at 5 MHz. The effective resolution is 8.8 bits considering 1 V dynamic range. The maximum sampling rate reaches up to 50 MSPS and readout rate of 15 MHz to keep noise smaller than 2.5 mV. The test results validate the feasibility of the MOS capacitor. Supported by National Natural Science Foundation of China (11375100), Strategic Pioneer Program on Space Sciences, Chinese Academy of Sciences (XDA04060606-06) and State Key Laboratory of Particle Detection and Electronics

  6. High-Energy-Density Electrolytic Capacitors

    NASA Technical Reports Server (NTRS)

    Yen, Shiao-Ping S.; Lewis, Carol R.

    1993-01-01

    Reductions in weight and volume make new application possible. Supercapacitors and improved ultracapacitors advanced electrolytic capacitors developed for use as electric-load-leveling devices in such applications as electric vehicle propulsion systems, portable power tools, and low-voltage pulsed power supplies. One primary advantage: offer power densities much higher than storage batteries. Capacitors used in pulse mode, with short charge and discharge times. Derived from commercially available ultracapacitors. Made of lightweight materials; incorporate electrode/electrolyte material systems capable of operation at voltages higher than previous electrode/electrolyte systems. By use of innovative designs and manufacturing processes, made in wide range of rated capacitances and in rated operating potentials ranging from few to several hundred volts.

  7. Evaluation and Characterization of Magnets and Capacitors

    SciTech Connect

    Seiber, L.E.; Cunningham, J.P.; Golik, S.S.; Armstrong, G.

    2006-10-15

    Advanced vehicle, fuel cell, hybrid electric vehicle (HEV), and plug in hybrid research and development is conducted by the U.S. Department of Energy (DOE) through its FreedomCAR and Vehicle Technologies (FCVT) program. The mission of this program is to develop more energy efficient and environmentally safe highway transportation technologies. Program activities include research, development, testing, technology validation, and technology transfer. These activities are done at the system and component levels. This report will discuss component level testing of prototype capacitors and magnets. As capacitor and magnet technologies mature, it is important to ascertain the limitations of these new technologies by subjecting the components to standardized tests to evaluate their capabilities. Test results will assist in the determination of their ability to provide improvements in power electronics and motor designs to meet the FCVT goals.

  8. Progress on electrocaloric multilayer ceramic capacitor development

    NASA Astrophysics Data System (ADS)

    Hirose, Sakyo; Usui, Tomoyasu; Crossley, Sam; Nair, Bhasi; Ando, Akira; Moya, Xavier; Mathur, Neil D.

    2016-06-01

    A multilayer capacitor comprising 19 layers of 38 μm-thick 0.9Pb(Mg1/3Nb2/3)O3-0.1PbTiO3 has elsewhere been shown to display electrocaloric temperature changes of 2.2 K due to field changes of 24 V μm-1, near ˜100 °C. Here we demonstrate temperature changes of 1.2 K in an equivalent device with 2.6 times the thermal mass, i.e., 49 layers that could tolerate 10.3 V μm-1. Breakdown was compromised by the increased number of layers, and occurred at 10.5 V μm-1 near the edge of a near-surface inner electrode. Further optimization is required to improve the breakdown strength of large electrocaloric multilayer capacitors for cooling applications.

  9. Recent progress of multilayer ceramic capacitors

    NASA Astrophysics Data System (ADS)

    Nomura, Takeshi

    1998-02-01

    Recently, reduction of production costs with maintaining high reliability is required for wider applications of capacitors. Ni-electrode multilayer ceramic capacitors (MLCCs) of BaTiO3-based dielectrics and AgPd-electrode MLCCs of relaxor materials were developed to meet the requirements. Thinner dielectriclayers, miniaturization, and high capacitance are also major requirements for MLCCs. In these circumstances, much effort has been paid in order to achieve higher reliability. Ni-electrode MLCCs are promising way to satisfy the requirements of high capacitance, low cost, and high reliability. Major problems about the reliability were mechanical fracture, degradation of insulation resistance, and capacitance aging. These phenomena are strongly affected by both chemical composition and producing process.

  10. Lecture 4: transmission lines and capacitors

    SciTech Connect

    Butcher, R.R.

    1980-01-01

    The topic of this lecture is pulse forming networks. The first item of discussion will be transmission lines because they are so prevalent, even if only in the form of coaxial cable. From there the subject will proceed to pulse-forming networks: the practical problems encountered with them, their advantages, and disadvantages. Capacitors will be our final topic, as they are the limiting factor in lumped transmission elements.

  11. Diagnostics and performance evaluation of multikilohertz capacitors

    SciTech Connect

    McDuff, G.; Nunnally, W.C.; Rust, K.; Sarjeant, J.

    1980-01-01

    The observed performance of nanofarad polypropylene-silicone oil, mica paper, and polytetrafluoroethylene-silicone oil capacitors discharged in a 100-ns, 1-kA pulse with a pulse repetition frequency of 1 kHz is presented. The test facility circuit, diagnostic parameters, and the preliminary test schedule are outlined as a basis for discussion of the observed failure locations and proposed failure mechanisms. Most of the test data and discussion presented involves the polypropylene-silicone oil units.

  12. Cryogenic Cermic Multilayer Capacitors for Power Electronics

    SciTech Connect

    Alberta, E. F.; Hackenberger, W. S.

    2006-03-31

    Recent advances in the areas of high temperature superconductors and low temperature MOSFET devices have opened the door to the possibility of developing highly efficient low-temperature power electronics. The most commonly used high-efficiency capacitors are based on high dielectric constant (K {approx} 1000-4000) barium titanate doped to yield and X7R temperature dependence ({+-}15% change in capacitance from -55 deg. C to 125 deg. C); however, below their minimum use temperature the capacitance drops-off quickly leading to a low volumetric efficiency and high temperature coefficient of capacitance (TCC) at cryogenic temperatures.A series of low temperature materials with moderate to high dielectric constants have been specifically developed for low temperature operation (below 80K). The capacitors fall into three main categories: low TCC, high volumetric efficiency, and energy storage. In the low TCC category, co-fired multilayer ceramic capacitors (MLCCs) were fabricated with capacitance values up to 62nF at 30K, TCCs from 0.9 to 2% below 80K, and losses on the order of 0.0001. In the high volumetric efficiency category, dielectrics with permittivities ranging from 1,000 to 30,000 were demonstrated.

  13. Evaluation of SAFT America, Inc. electrochemical capacitors

    SciTech Connect

    Wright, R.B.; Murphy, T.C.

    1997-12-01

    The electrochemical capacitor devices described in this report were deliverables from Lawrence Berkeley National Laboratory (LBNL), Contract No. 4606510 with SAFT America, Inc., as part of LBNL`s exploratory research program. Dr. Kimio Kinoshita is the Program Manager at LBNL. The contract was in support of the US Department of Energy`s (DOE) exploratory electrochemical energy storage program which includes development projects for a wide variety of advanced high-energy/high-power energy storage systems for electric and hybrid vehicle programs. The DOE is currently developing various electrochemical capacitors as candidate power assist devices for the Partnership for a New Generation of Vehicles (PNGV) fast-response engine requirements. The LBNL contract with SAFT America, Inc., was intended to evaluate various activated carbon-based electrode formulations and develop an electrical model of the double-layer capacitor. The goal is to design and deliver prototypes meeting the DOE requirement of > 1,000 W/kg, 16 Wh/kg. Deliverables were sent to the INEEL EST laboratory for independent testing and evaluation. The following report describes performance testing on ten devices received September 2, 1996. Due to the initial performance of these early devices, life-cycle testing was not conducted. Additional devices, with improved performance, are expected to be tested. Future results will be reported in a follow-on report.

  14. Conducting Multilevel Analyses in Medical Education

    ERIC Educational Resources Information Center

    Zyphur, Michael J.; Kaplan, Seth A.; Islam, Gazi; Barsky, Adam P.; Franklin, Michael S.

    2008-01-01

    A significant body of education literature has begun using multilevel statistical models to examine data that reside at multiple levels of analysis. In order to provide a primer for medical education researchers, the current work gives a brief overview of some issues associated with multilevel statistical modeling. To provide an example of this…

  15. A Multilevel Assessment of Differential Item Functioning.

    ERIC Educational Resources Information Center

    Shen, Linjun

    A multilevel approach was proposed for the assessment of differential item functioning and compared with the traditional logistic regression approach. Data from the Comprehensive Osteopathic Medical Licensing Examination for 2,300 freshman osteopathic medical students were analyzed. The multilevel approach used three-level hierarchical generalized…

  16. Multilevel Interventions: Study Design and Analysis Issues

    PubMed Central

    Gross, Cary P.; Zaslavsky, Alan M.; Taplin, Stephen H.

    2012-01-01

    Multilevel interventions, implemented at the individual, physician, clinic, health-care organization, and/or community level, increasingly are proposed and used in the belief that they will lead to more substantial and sustained changes in behaviors related to cancer prevention, detection, and treatment than would single-level interventions. It is important to understand how intervention components are related to patient outcomes and identify barriers to implementation. Designs that permit such assessments are uncommon, however. Thus, an important way of expanding our knowledge about multilevel interventions would be to assess the impact of interventions at different levels on patients as well as the independent and synergistic effects of influences from different levels. It also would be useful to assess the impact of interventions on outcomes at different levels. Multilevel interventions are much more expensive and complicated to implement and evaluate than are single-level interventions. Given how little evidence there is about the value of multilevel interventions, however, it is incumbent upon those arguing for this approach to do multilevel research that explicates the contributions that interventions at different levels make to the desired outcomes. Only then will we know whether multilevel interventions are better than more focused interventions and gain greater insights into the kinds of interventions that can be implemented effectively and efficiently to improve health and health care for individuals with cancer. This chapter reviews designs for assessing multilevel interventions and analytic ways of controlling for potentially confounding variables that can account for the complex structure of multilevel data. PMID:22623596

  17. Structural optimization by multilevel decomposition

    NASA Technical Reports Server (NTRS)

    Sobieszczanski-Sobieski, J.; James, B.; Dovi, A.

    1983-01-01

    A method is described for decomposing an optimization problem into a set of subproblems and a coordination problem which preserves coupling between the subproblems. The method is introduced as a special case of multilevel, multidisciplinary system optimization and its algorithm is fully described for two level optimization for structures assembled of finite elements of arbitrary type. Numerical results are given for an example of a framework to show that the decomposition method converges and yields results comparable to those obtained without decomposition. It is pointed out that optimization by decomposition should reduce the design time by allowing groups of engineers, using different computers to work concurrently on the same large problem.

  18. High power density capacitor and method of fabrication

    DOEpatents

    Tuncer, Enis

    2012-11-20

    A ductile preform for making a drawn capacitor includes a plurality of electrically insulating, ductile insulator plates and a plurality of electrically conductive, ductile capacitor plates. Each insulator plate is stacked vertically on a respective capacitor plate and each capacitor plate is stacked on a corresponding insulator plate in alignment with only one edge so that other edges are not in alignment and so that each insulator plate extends beyond the other edges. One or more electrically insulating, ductile spacers are disposed in horizontal alignment with each capacitor plate along the other edges and the pattern is repeated so that alternating capacitor plates are stacked on alternating opposite edges of the insulator plates. A final insulator plate is positioned at an extremity of the preform. The preform may then be drawn to fuse the components and decrease the dimensions of the preform that are perpendicular to the direction of the draw.

  19. Method of manufacturing a shapeable short-resistant capacitor

    DOEpatents

    Taylor, Ralph S.; Myers, John D.; Baney, William J.

    2013-04-02

    A method that employs a novel combination of conventional fabrication techniques provides a ceramic short-resistant capacitor that is bendable and/or shapeable to provide a multiple layer capacitor that is extremely compact and amenable to desirable geometries. The method allows thinner and more flexible ceramic capacitors to be made. The method includes forming a first thin metal layer on a substrate; depositing a thin, ceramic dielectric layer over the metal layer; depositing a second thin metal layer over the dielectric layer to form a capacitor exhibiting a benign failure mode; and separating the capacitor from the substrate. The method may also include bending the resulting capacitor into a serpentine arrangement with gaps between the layers that allow venting of evaporated electrode material in the event of a benign failure.

  20. A compact 100 kV high voltage glycol capacitor

    NASA Astrophysics Data System (ADS)

    Wang, Langning; Liu, Jinliang; Feng, Jiahuai

    2015-01-01

    A high voltage capacitor is described in this paper. The capacitor uses glycerol as energy storage medium, has a large capacitance close to 1 nF, can hold off voltages of up to 100 kV for μs charging time. Allowing for low inductance, the capacitor electrode is designed as coaxial structure, which is different from the common structure of the ceramic capacitor. With a steady capacitance at different frequencies and a high hold-off voltage of up to 100 kV, the glycol capacitor design provides a potential substitute for the ceramic capacitors in pulse-forming network modulator to generate high voltage pulses with a width longer than 100 ns.

  1. Thermal Modeling of Snap-in Type Aluminum Electrolytic Capacitor

    NASA Astrophysics Data System (ADS)

    Koizumi, Katsuhiro; Ishizuka, Masaru; Nakagawa, Shinji; Hatakeyama, Tomoyuki

    The electrolytic capacitor is one of the most important components for the thermal analysis of electronic equipment. To predict component and system temperatures, the thermal flow simulation technique has been applied to thermal design of electronic equipment. In this study, we examined a compact modeling method for electrolytic capacitors in order to simulate thermal flow based on the computational fluid dynamics (CFD) code. To obtain fundamental data for the thermal modeling method, first, we conducted experiments to identify the major thermal path of electrolytic capacitors in actual electronic equipment by using a switch mode power supply unit. Next, to verify the validity of the thermal model, a benchmark experiment was conducted to obtain actual measurement data of the temperature rise of electrolytic capacitors under various operating conditions. The thermal model of the electrolytic capacitor was presented based on the CFD code. In this paper, we describe in particular the snap-in type electrolytic capacitor.

  2. Energy-storage pulsed-power capacitor technology

    SciTech Connect

    Laghari, J.R.; Sarjeant, W.J. )

    1992-01-01

    This paper addresses fundamentals of dielectric capacitor technology and multifactor stress aging of all classes of insulating media that form elements of this technology. It is directed toward the delineation of failure processes in highly stressed compact capacitors. Factors affecting the complex aging processes such as thermal, electromechanical, and partial discharges are discussed. Diagnostic measurement techniques available and those being developed to determine material degradation affecting available life and failure probability of capacitors are presented.

  3. MOSFET and MOS capacitor responses to ionizing radiation

    NASA Technical Reports Server (NTRS)

    Benedetto, J. M.; Boesch, H. E., Jr.

    1984-01-01

    The ionizing radiation responses of metal oxide semiconductor (MOS) field-effect transistors (FETs) and MOS capacitors are compared. It is shown that the radiation-induced threshold voltage shift correlates closely with the shift in the MOS capacitor inversion voltage. The radiation-induced interface-state density of the MOSFETs and MOS capacitors was determined by several techniques. It is shown that the presence of 'slow' states can interfere with the interface-state measurements.

  4. High energy density capacitor testing for the AFWL SHIVA

    SciTech Connect

    Smith, D.L.; Reinovsky, R.E.

    1981-01-01

    The SHIVA II Prime upgrade consists of replacing the existing 3.3 kJ, 1.85 ..mu..F capacitors with plug-in higher energy density capacitors. Based on capacitor development work by manufacturers it appears that a nominal 6 ..mu..F, 60 kV capacitor in an 11'' x 14'' can is near the limits of current technology. Using the 6 ..mu..F, 10.8 kJ capacitor results in a factor of 3 increase in stored energy at no increase in operational voltage. The equivalent system capacitance will then be 864 ..mu..F at 120 kV (+-60 kV) or 6.22 MJ. The best testing technique is one which duplicates, as nearly as reasonable, the actual parameters the capacitors would see in the full-scale system. Lifetime testing and analysis of small samples of high energy density (HED) discharge capacitors at the AFWL were conducted to find a component suitable for upgrading the SHIVA capacitor bank to a 6 MJ facility. Evaluation was performed with discharge conditions of approximately 250 kA per capacitor at 60 to 70% reversal and < 2 ..mu..s quarter period. Dielectric systems including Kraft paper with caster oil impregnant and Kraft paper, polypropylene with DiOctyl Phthalate (DOP) impregnant were tested.

  5. Pressure Effects Analysis of National Ignition Facility Capacitor Module Events

    SciTech Connect

    Brereton, S; Ma, C; Newton, M; Pastrnak, J; Price, D; Prokosch, D

    1999-11-22

    Capacitors and power conditioning systems required for the National Ignition Facility (NIF) have experienced several catastrophic failures during prototype demonstration. These events generally resulted in explosion, generating a dramatic fireball and energetic shrapnel, and thus may present a threat to the walls of the capacitor bay that houses the capacitor modules. The purpose of this paper is to evaluate the ability of the capacitor bay walls to withstand the overpressure generated by the aforementioned events. Two calculations are described in this paper. The first one was used to estimate the energy release during a fireball event and the second one was used to estimate the pressure in a capacitor module during a capacitor explosion event. Both results were then used to estimate the subsequent overpressure in the capacitor bay where these events occurred. The analysis showed that the expected capacitor bay overpressure was less than the pressure tolerance of the walls. To understand the risk of the above events in NIF, capacitor module failure probabilities were also calculated. This paper concludes with estimates of the probability of single module failure and multi-module failures based on the number of catastrophic failures in the prototype demonstration facility.

  6. Ceramic capacitor exhibiting graceful failure by self-clearing, method for fabricating self-clearing capacitor

    DOEpatents

    Kaufman, David Y.; Saha, Sanjib

    2006-08-29

    A short-resistant capacitor comprises an electrically conductive planar support substrate having a first thickness, a ceramic film deposited over the support substrate, thereby defining a ceramic surface; and a metallic film deposited over the ceramic surface, said film having a second thickness which is less than the first thickness and which is between 0.01 and 0.1 microns.

  7. Soft capacitor fibers for electronic textiles

    NASA Astrophysics Data System (ADS)

    Gu, Jian Feng; Gorgutsa, Stephan; Skorobogatiy, Maksim

    2010-09-01

    A highly flexible, conductive polymer-based fiber with high electric capacitance is reported. The fiber is fabricated using fiber drawing method, where a multimaterial macroscopic preform is drawn into a submillimeter capacitor microstructured fiber. A typical measured capacitance per unit length of our fibers is 60-100 nF/m which is about 3 orders magnitude higher than that of a coaxial cable of a comparable diameter. The fiber has a transverse resistivity of 5 kΩ m. Softness, lightweight, absence of liquid electrolyte, and ease of scalability to large production volumes make the fibers interesting for various smart textile applications.

  8. Simulation of capacitor charging power supplies

    NASA Technical Reports Server (NTRS)

    Newton, S. R.; Nelms, R. M.

    1990-01-01

    By neglecting losses and other nonidealities, the authors were able to derive a simple single-loop equivalent circuit for each mode of operation of the series resonant converter. From these equivalent circuits, a good approximation of the current and voltages within the converter was obtained, despite the simplified approach taken. It is pointed out that designers of capacitor charging power supplies can utilize this approach in deciding what type of control strategy is needed to obtain a desired characteristic. Once the basic topology of the power supply has been determined, a detailed simulation could be implemented using one of the general-purpose software packages available.

  9. Planarization of metal films for multilevel interconnects

    DOEpatents

    Tuckerman, D.B.

    1989-03-21

    In the fabrication of multilevel integrated circuits, each metal layer is planarized by heating to momentarily melt the layer. The layer is melted by sweeping laser pulses of suitable width, typically about 1 microsecond duration, over the layer in small increments. The planarization of each metal layer eliminates irregular and discontinuous conditions between successive layers. The planarization method is particularly applicable to circuits having ground or power planes and allows for multilevel interconnects. Dielectric layers can also be planarized to produce a fully planar multilevel interconnect structure. The method is useful for the fabrication of VLSI circuits, particularly for wafer-scale integration. 6 figs.

  10. Planarization of metal films for multilevel interconnects

    DOEpatents

    Tuckerman, David B.

    1987-01-01

    In the fabrication of multilevel integrated circuits, each metal layer is anarized by heating to momentarily melt the layer. The layer is melted by sweeping laser pulses of suitable width, typically about 1 microsecond duration, over the layer in small increments. The planarization of each metal layer eliminates irregular and discontinuous conditions between successive layers. The planarization method is particularly applicable to circuits having ground or power planes and allows for multilevel interconnects. Dielectric layers can also be planarized to produce a fully planar multilevel interconnect structure. The method is useful for the fabrication of VLSI circuits, particularly for wafer-scale integration.

  11. Planarization of metal films for multilevel interconnects

    DOEpatents

    Tuckerman, David B.

    1989-01-01

    In the fabrication of multilevel integrated circuits, each metal layer is anarized by heating to momentarily melt the layer. The layer is melted by sweeping laser pulses of suitable width, typically about 1 microsecond duration, over the layer in small increments. The planarization of each metal layer eliminates irregular and discontinuous conditions between successive layers. The planarization method is particularly applicable to circuits having ground or power planes and allows for multilevel interconnects. Dielectric layers can also be planarized to produce a fully planar multilevel interconnect structure. The method is useful for the fabrication of VLSI circuits, particularly for wafer-scale integration.

  12. Planarization of metal films for multilevel interconnects

    DOEpatents

    Tuckerman, D.B.

    1985-08-23

    In the fabrication of multilevel integrated circuits, each metal layer is planarized by heating to momentarily melt the layer. The layer is melted by sweeping laser pulses of suitable width, typically about 1 microsecond duration, over the layer in small increments. The planarization of each metal layer eliminates irregular and discontinuous conditions between successive layers. The planarization method is particularly applicable to circuits having ground or power planes and allows for multilevel interconnects. Dielectric layers can also be planarized to produce a fully planar multilevel interconnect structure. The method is useful for the fabrication of VLSI circuits, particularly for wafer-scale integration.

  13. Planarization of metal films for multilevel interconnects

    DOEpatents

    Tuckerman, D.B.

    1985-06-24

    In the fabrication of multilevel integrated circuits, each metal layer is planarized by heating to momentarily melt the layer. The layer is melted by sweeping lase pulses of suitable width, typically about 1 microsecond duration, over the layer in small increments. The planarization of each metal layer eliminates irregular and discontinuous conditions between successive layers. The planarization method is particularly applicable to circuits having ground or power planes and allows for multilevel interconnects. Dielectric layers can also be planarized to produce a fully planar multilevel interconnect structure. The method is useful for the fabrication of VLSI circuits, particularly for wafer-scale integration.

  14. Evaluation of high temperature capacitor dielectrics

    NASA Technical Reports Server (NTRS)

    Hammoud, Ahmad N.; Myers, Ira T.

    1992-01-01

    Experiments were carried out to evaluate four candidate materials for high temperature capacitor dielectric applications. The materials investigated were polybenzimidazole polymer and three aramid papers: Voltex 450, Nomex 410, and Nomex M 418, an aramid paper containing 50 percent mica. The samples were heat treated for six hours at 60 C and the direct current and 60 Hz alternating current breakdown voltages of both dry and impregnated samples were obtained in a temperature range of 20 to 250 C. The samples were also characterized in terms of their dielectric constant, dielectric loss, and conductivity over this temperature range with an electrical stress of 60 Hz, 50 V/mil present. Additional measurements are underway to determine the volume resistivity, thermal shrinkage, and weight loss of the materials. Preliminary data indicate that the heat treatment of the films slightly improves the dielectric properties with no influence on their breakdown behavior. Impregnation of the samples leads to significant increases in both alternating and direct current breakdown strength. The results are discussed and conclusions made concerning their suitability as high temperature capacitor dielectrics.

  15. Capacitors Would Help Protect Against Hypervelocity Impacts

    NASA Technical Reports Server (NTRS)

    Edwards, David; Hubbs, Whitney; Hovater, Mary

    2007-01-01

    A proposal investigates alternatives to the present bumper method of protecting spacecraft against impacts of meteoroids and orbital debris. The proposed method is based on a British high-voltage-capacitance technique for protecting armored vehicles against shaped-charge warheads. A shield, according to the proposal, would include a bare metal outer layer separated by a gap from an inner metal layer covered with an electrically insulating material. The metal layers would constitute electrodes of a capacitor. A bias potential would be applied between the metal layers. A particle impinging at hypervelocity on the outer metal layer would break apart into a debris cloud that would penetrate the electrical insulation on the inner metal layer. The cloud would form a path along which electric current could flow between the metal layers, thereby causing the capacitor to discharge. With proper design, the discharge current would be large enough to vaporize the particles in the debris cloud to prevent penetration of the spacecraft. The shield design can be mass optimized to be competitive with existing bumper designs. Parametric studies were proposed to determine optimum correction between bias voltage, impacting particle velocity, gap space, and insulating material required to prevent spacecraft penetration.

  16. A Magnesium-Activated Carbon Hybrid Capacitor

    SciTech Connect

    Yoo, HD; Shterenberg, I; Gofer, Y; Doe, RE; Fischer, CC; Ceder, G; Aurbach, D

    2013-12-11

    Prototype cells of hybrid capacitor were developed, comprising activated carbon (AC) cloth and magnesium (Mg) foil as the positive and negative electrodes, respectively. The electrolyte solution included ether solvent (TBF) and a magnesium organo-halo-aluminate complex 0.25 M Mg2Cl3+-Ph2AlCl2-. In this solution Mg can be deposited/dissolved reversibly for thousands of cycles with high reversibility (100% cycling efficiency). The main barrier for integrating porous AC electrodes with this electrolyte solution was the saturation of the pores with the large ions in the AC prior to reaching the potential limit. This is due to the existence of bulky Mg and Al based ionic complexes consisting Cl, alkyl or aryl (R), and THF ligands. This problem was resolved by adding 0.5 M of lithium chloride (LiCl), thus introducing smaller ionic species to the solution. This Mg hybrid capacitor system demonstrated a stable cycle performance for many thousands of cycles with a specific capacitance of 90 Fg(-1) for the AC positive electrodes along a potential range of 2.4 V. (C) 2014 The Electrochemical Society. All rights reserved.

  17. Evaluation of high temperature capacitor dielectrics

    NASA Astrophysics Data System (ADS)

    Hammoud, Ahmad N.; Myers, Ira T.

    Experiments were carried out to evaluate four candidate materials for high temperature capacitor dielectric applications. The materials investigated were polybenzimidazole polymer and three aramid papers: Voltex 450, Nomex 410, and Nomex M 418, an aramid paper containing 50 percent mica. The samples were heat treated for six hours at 60 C and the direct current and 60 Hz alternating current breakdown voltages of both dry and impregnated samples were obtained in a temperature range of 20 to 250 C. The samples were also characterized in terms of their dielectric constant, dielectric loss, and conductivity over this temperature range with an electrical stress of 60 Hz, 50 V/mil present. Additional measurements are underway to determine the volume resistivity, thermal shrinkage, and weight loss of the materials. Preliminary data indicate that the heat treatment of the films slightly improves the dielectric properties with no influence on their breakdown behavior. Impregnation of the samples leads to significant increases in both alternating and direct current breakdown strength. The results are discussed and conclusions made concerning their suitability as high temperature capacitor dielectrics.

  18. New series half-bridge converters with the balance input split capacitor voltages

    NASA Astrophysics Data System (ADS)

    Lin, Bor-Ren; Chiang, Huann-Keng; Wang, Shang-Lun

    2016-03-01

    This article presents a new dc/dc converter to perform the main functions of zero voltage switching (ZWS), low converter size, high switching frequency and low-voltage stress. Metal-oxide-semiconductor field-effect transistors (MOSFETs) with high switching frequency are used to reduce the converter size and increase circuit efficiency. To overcome low-voltage stress and high turn-on resistance of MOSFETs, the series half-bridge topology is adopted in the proposed converter. Hence, the low-voltage stress MOSFETs can be used for medium-input voltage applications. The asymmetric pulse-width modulation is used to generate the gating signals and achieve the ZWS. On the secondary side, the parallel connection of two diode rectifiers is adopted to reduce the current rating of passive components. On the primary side, the series connection of two transformers is used to balance two output inductor currents. Two flying capacitors are used to automatically balance the input split capacitor voltages. Finally, experiments with 1000 W rated power are performed to verify the theoretical analysis and the effectiveness of proposed converter.

  19. Electrode/Dielectric Strip For High-Energy-Density Capacitor

    NASA Technical Reports Server (NTRS)

    Yen, Shiao-Ping S.

    1994-01-01

    Improved unitary electrode/dielectric strip serves as winding in high-energy-density capacitor in pulsed power supply. Offers combination of qualities essential for high energy density: high permittivity of dielectric layers, thinness, and high resistance to breakdown of dielectric at high electric fields. Capacitors with strip material not impregnated with liquid.

  20. Two-Capacitor Problem: A More Realistic View.

    ERIC Educational Resources Information Center

    Powell, R. A.

    1979-01-01

    Discusses the two-capacitor problem by considering the self-inductance of the circuit used and by determining how well the usual series RC circuit approximates the two-capacitor problem when realistic values of L, C, and R are chosen. (GA)

  1. Capacitors in Series: A Laboratory Activity to Promote Critical Thinking.

    ERIC Educational Resources Information Center

    Noll, Ellis D.; Kowalski, Ludwik

    1996-01-01

    Describes experiments designed to explore the distribution of potential difference between two uncharged capacitors when they are suddenly connected to a source of constant voltage. Enables students to explore the evolution of a system in which initial voltage distribution depends on capacitor values, and the final voltage distribution depends on…

  2. Performance of electric double layer capacitors with polymer gel electrolytes

    SciTech Connect

    Ishikawa, Masashi; Kishino, Takahiro; Katada, Naoji; Morita, Masayuki

    2000-07-01

    Polymer gel electrolytes consisting of poly(vinylidene fluoride) (PVdF), tetraethylammonium tetrafluoroborate (TEABF{sub 4}), and propylene carbonate (PC) as a plasticizer have been investigated for electric double layer capacitors. The PVdF gel electrolytes showed high ionic conductivity (ca. 6 mS/cm at 298 K). To assemble model capacitors with the PVdF gel electrolytes and activated carbon fiber cloth electrodes, a pair of the fixed electrodes was soaked in a precursor solution containing PC, PVdF, and TEABF{sub 4}, followed by evaporation of the PC solvent in a vacuum oven. The resulting gel electrolytes were in good contact with the electrodes. The model capacitors with the PVdF gel electrolytes showed a large value of capacitance and high coulombic efficiency in operation voltage ranges of 1--2 and 1--3 V. It is worth noting that the capacitors with the PVdF electrolytes showed long voltage retention in a self-discharge test. These good characteristics of the gel capacitors were comparable to those of typical double layer capacitors with a liquid organic electrolyte containing PC and TEABF{sub 4}; rather, the voltage retentivity of the PVdF gel capacitors was much superior to that of the capacitors with the organic electrolyte.

  3. Scalable Adaptive Multilevel Solvers for Multiphysics Problems

    SciTech Connect

    Xu, Jinchao

    2014-12-01

    In this project, we investigated adaptive, parallel, and multilevel methods for numerical modeling of various real-world applications, including Magnetohydrodynamics (MHD), complex fluids, Electromagnetism, Navier-Stokes equations, and reservoir simulation. First, we have designed improved mathematical models and numerical discretizaitons for viscoelastic fluids and MHD. Second, we have derived new a posteriori error estimators and extended the applicability of adaptivity to various problems. Third, we have developed multilevel solvers for solving scalar partial differential equations (PDEs) as well as coupled systems of PDEs, especially on unstructured grids. Moreover, we have integrated the study between adaptive method and multilevel methods, and made significant efforts and advances in adaptive multilevel methods of the multi-physics problems.

  4. Advanced Wet Tantalum Capacitors: Design, Specifications and Performance

    NASA Technical Reports Server (NTRS)

    Teverovsky, Alexander

    2016-01-01

    Insertion of new types of commercial, high volumetric efficiency wet tantalum capacitors in space systems requires reassessment of the existing quality assurance approaches that have been developed for capacitors manufactured to MIL-PRF-39006 requirements. The specifics of wet electrolytic capacitors is that leakage currents flowing through electrolyte can cause gas generation resulting in building up of internal gas pressure and rupture of the case. The risk associated with excessive leakage currents and increased pressure is greater for high value advanced wet tantalum capacitors, but it has not been properly evaluated yet. This presentation gives a review of specifics of the design, performance, and potential reliability risks associated with advanced wet tantalum capacitors. Problems related to setting adequate requirements for DPA, leakage currents, hermeticity, stability at low and high temperatures, ripple currents for parts operating in vacuum, and random vibration testing are discussed. Recommendations for screening and qualification to reduce risks of failures have been suggested.

  5. Absorption Voltages and Insulation Resistance in Ceramic Capacitors with Cracks

    NASA Technical Reports Server (NTRS)

    Teverovsky, Alexander

    2016-01-01

    Time dependence of absorption voltages (Vabs) in different types of low-voltage X5R and X7R ceramic capacitors was monitored for a maximum duration of hundred hours after polarization. To evaluate the effect of mechanical defects on Vabs, cracks in the dielectric were introduced either mechanically or by thermal shock. The maximum absorption voltage, time to roll-off, and the rate of voltage decrease are shown to depend on the crack-related leakage currents and insulation resistance in the parts. A simple model that is based on the Dow equivalent circuit for capacitors with absorption has been developed to assess the insulation resistance of capacitors. Standard measurements of the insulation resistance, contrary to the measurements based on Vabs, are not sensitive to the presence of mechanical defects and fail to reveal capacitors with cracks. Index Terms: Ceramic capacitor, insulation resistance, dielectric absorption, cracking.

  6. Evaluation of Commercial Automotive-Grade BME Capacitors

    NASA Technical Reports Server (NTRS)

    Liu, Donhang

    2014-01-01

    Three Ni-BaTiO3 ceramic capacitor lots with the same specification (chip size, capacitance, and rated voltage) and the same reliability level, made by three different manufacturers, were degraded using highly accelerated life stress testing (HALST) with the same temperature and applied voltage conditions. The reliability, as characterized by mean time to failure (MTTF), differed by more than one order of magnitude among the capacitor lots. A theoretical model based on the existence of depletion layers at grain boundaries and the entrapment of oxygen vacancies has been proposed to explain the MTTF difference among these BME capacitors. It is the conclusion of this model that reliability will not be improved simply by increasing the insulation resistance of a BME capacitor. Indeed, Ni-BaTiO3 ceramic capacitors with a smaller degradation rate constant K will always give rise to a longer reliability life.

  7. Autonomous Flying Controls Testbed

    NASA Technical Reports Server (NTRS)

    Motter, Mark A.

    2005-01-01

    The Flying Controls Testbed (FLiC) is a relatively small and inexpensive unmanned aerial vehicle developed specifically to test highly experimental flight control approaches. The most recent version of the FLiC is configured with 16 independent aileron segments, supports the implementation of C-coded experimental controllers, and is capable of fully autonomous flight from takeoff roll to landing, including flight test maneuvers. The test vehicle is basically a modified Army target drone, AN/FQM-117B, developed as part of a collaboration between the Aviation Applied Technology Directorate (AATD) at Fort Eustis,Virginia and NASA Langley Research Center. Several vehicles have been constructed and collectively have flown over 600 successful test flights.

  8. Complexity and Fly Swarms

    NASA Astrophysics Data System (ADS)

    Cates, Grant; Murray, Joelle

    Complexity is the study of phenomena that emerge from a collection of interacting objects and arises in many systems throughout physics, biology, finance, economics and more. Certain kinds of complex systems can be described by self-organized criticality (SOC). An SOC system is one that is internally driven towards some critical state. Recent experimental work suggests scaling behavior of fly swarms-one of the hallmarks of an SOC system. Our goal is to look for SOC behavior in computational models of fly swarms.

  9. Robust Two-Dimensional Stack Capacitor Technologies for 64 Mbit One-Transistor-One-Capacitor Ferroelectric Random Access Memory

    NASA Astrophysics Data System (ADS)

    Jung, Ju-Young; Joo, Heung-Jin; Park, Jung-Hoon; Kang, Seung-Kuk; Kim, Hwi-San; Choi, Do-Yeon; Kim, Jai-Hyun; Lee, Eun-Sun; Hong, Young-Ki; Kim, Hyun-Ho; Jung, Dong-Jin; Kang, Young-Min; Lee, Sung-Yung; Jeong, Hong-Sik; Kim, Kinam

    2007-04-01

    It is very important to develop capacitor module technologies such as robust Pb(ZrxTi1-x)O3 (PZT) film technology at nm scaled PZT thickness and damage minimized ferroelectric capacitor etching technology are crucial for the success of high density one-transistor-one-capacitor (1T1C) ferroelectric random access memory (FRAM). We resolved this issue from the change of the capacitor etching system and optimization of the PZT/SrRuO3 (SRO) deposition process. As a result, we realized a highly reliable sensing window for 64 Mbit 1T1C FRAM that were realized by novel technologies such as robust MOCVD PZT deposition technologies, optimized SRO electrode and damage minimized ferroelectric capacitor etching technologies.

  10. Alternative Methods for Assessing Mediation in Multilevel Data: The Advantages of Multilevel SEM

    ERIC Educational Resources Information Center

    Preacher, Kristopher J.; Zhang, Zhen; Zyphur, Michael J.

    2011-01-01

    Multilevel modeling (MLM) is a popular way of assessing mediation effects with clustered data. Two important limitations of this approach have been identified in prior research and a theoretical rationale has been provided for why multilevel structural equation modeling (MSEM) should be preferred. However, to date, no empirical evidence of MSEM's…

  11. Capacitor with a composite carbon foam electrode

    DOEpatents

    Mayer, S.T.; Pekala, R.W.; Kaschmitter, J.L.

    1999-04-27

    Carbon aerogels used as a binder for granularized materials, including other forms of carbon and metal additives, are cast onto carbon or metal fiber substrates to form composite carbon thin film sheets. The thin film sheets are utilized in electrochemical energy storage applications, such as electrochemical double layer capacitors (aerocapacitors), lithium based battery insertion electrodes, fuel cell electrodes, and electrocapacitive deionization electrodes. The composite carbon foam may be formed by prior known processes, but with the solid particles being added during the liquid phase of the process, i.e. prior to gelation. The other forms of carbon may include carbon microspheres, carbon powder, carbon aerogel powder or particles, graphite carbons. Metal and/or carbon fibers may be added for increased conductivity. The choice of materials and fibers will depend on the electrolyte used and the relative trade off of system resistivity and power to system energy. 1 fig.

  12. Low temperature double-layer capacitors

    NASA Technical Reports Server (NTRS)

    Brandon, Erik J. (Inventor); Smart, Marshall C. (Inventor); West, William C. (Inventor)

    2011-01-01

    Double-layer capacitors capable of operating at extremely low temperatures (e.g., as low as -75.degree. C.) are disclosed. Electrolyte solutions combining a base solvent (e.g., acetonitrile) and a cosolvent are employed to lower the melting point of the base electrolyte. Example cosolvents include methyl formate, ethyl acetate, methyl acetate, propionitrile, butyronitrile, and 1,3-dioxolane. An optimized concentration (e.g., 0.10 M to 0.75 M) of salt, such as tetraethylammonium tetrafluoroborate, is dissolved into the electrolyte solution. In some cases (e.g., 1,3-dioxolane cosolvent) additives, such as 2% by volume triethylamine, may be included in the solvent mixture to prevent polymerization of the solution. Conventional device form factors and structural elements (e.g., porous carbon electrodes and a polyethylene separator) may be employed.

  13. Capacitor with a composite carbon foam electrode

    DOEpatents

    Mayer, Steven T.; Pekala, Richard W.; Kaschmitter, James L.

    1999-01-01

    Carbon aerogels used as a binder for granularized materials, including other forms of carbon and metal additives, are cast onto carbon or metal fiber substrates to form composite carbon thin film sheets. The thin film sheets are utilized in electrochemical energy storage applications, such as electrochemical double layer capacitors (aerocapacitors), lithium based battery insertion electrodes, fuel cell electrodes, and electrocapacitive deionization electrodes. The composite carbon foam may be formed by prior known processes, but with the solid partides being added during the liquid phase of the process, i.e. prior to gelation. The other forms of carbon may include carbon microspheres, carbon powder, carbon aerogel powder or particles, graphite carbons. Metal and/or carbon fibers may be added for increased conductivity. The choice of materials and fibers will depend on the electrolyte used and the relative trade off of system resistivity and power to system energy.

  14. Carbon Film Electrodes For Super Capacitor Applications

    DOEpatents

    Tan, Ming X.

    1999-07-20

    A method for treating an organic polymer material, preferably a vinylidene chloride/vinyl chloride copolymer (Saran) to produce a flat sheet of carbon film material having a high surface area (.apprxeq.1000 m.sup.2 /g) suitable as an electrode material for super capacitor applications. The method comprises heating a vinylidene chloride/vinyl chloride copolymer film disposed between two spaced apart graphite or ceramic plates to a first temperature of about 160.degree. C. for about 14 hours to form a stabilized vinylidene chloride/vinyl chloride polymer film, thereafter heating the stabilized film to a second temperature of about 750.degree. C. in an inert atmosphere for about one hour to form a carbon film; and finally activating the carbon film to increase the surface area by heating the carbon film in an oxidizing atmosphere to a temperature of at least 750-850.degree. C. for between 1-6 hours.

  15. Design definition of a mechanical capacitor

    NASA Technical Reports Server (NTRS)

    Michaelis, T. D.; Schlieban, E. W.; Scott, R. D.

    1977-01-01

    A design study and analyses of a 10 kW-hr, 15 kW mechanical capacitor system was studied. It was determined that magnetically supported wheels constructed of advanced composites have the potential for high energy density and high power density. Structural concepts are analyzed that yield the highest energy density of any structural design yet reported. Particular attention was paid to the problem of 'friction' caused by magnetic and I to the second power R losses in the suspension and motor-generator subsystems, and low design friction levels have been achieved. The potentially long shelf life of this system, and the absence of wearing parts, provide superior performance over conventional flywheels supported with mechanical bearings. Costs and economies of energy storage wheels were reviewed briefly.

  16. Economic Impact of Stable Flies

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A dynamic model was created to estimate the economic impact of stable flies on livestock production. Based upon a nationwide average of 10 stable flies per animal for 3 months per year, the model estimates the impact of stable flies to be $543 million to the dairy industry, $1.34 billion to pasture ...

  17. Learning to Fly.

    ERIC Educational Resources Information Center

    Weil, Patricia E.

    1983-01-01

    Presents information on where to learn to fly, which aircraft is best for this purpose, and approximate costs. Includes additional information on certificates, licenses, and ratings, and a description of the two phases of the General Aviation Manufacturers Association flight training program. (JN)

  18. Flying High with Spring.

    ERIC Educational Resources Information Center

    Harrington, Carolyn Lang

    2000-01-01

    Presents an art activity for first grade that uses multicolor scratch paper. Explains that students make scratch-drawings of bird nests, then, as a class, discuss types of birds and bird positions (such as sitting or flying), and finally each creates a bird to add to the nest. (CMK)

  19. Fly on the Wall

    ERIC Educational Resources Information Center

    Berry, Dave; Korpan, Cynthia

    2009-01-01

    This paper describes the implementation of a peer observation program at the University of Victoria called the Lecture Club. The observers are not interactive during the class--they are the proverbial flies on the wall. The paper identifies the program as self-developmental, discussing the attributes of this learning-to-teach and peer-sharing…

  20. Wisdom from the fly.

    PubMed

    Rieder, Leila E; Larschan, Erica N

    2014-11-01

    Arguably, almost all research in Drosophila can be considered basic research, yet many of the most essential and fundamental concepts of human genetics were first decoded in the fly. Although the fly genome, which is organized into only four chromosomes, is approximately one-twentieth the size of the human genome, it contains roughly the same number of genes, and up to 75% of human disease-related genes have Drosophila homologues [1]. The fly was prized for its simplicity and utility even before such compelling homology with humans was apparent. Since Thomas Hunt Morgan began his seminal experiments over a century ago (Table 1), the Drosophila system has revealed countless key mechanisms by which cells function, including the factors that maintain chromatin and the signaling pathways that control cell fate determination and organism development. More recently, the fly has emerged as a critical neurobiological tool and disease model for a range of genetic disorders. In this review, we present a brief retrospective of Drosophila as an indispensable genetic system and discuss some of the many contributions, past and present, of this facile system to human genetics. PMID:25161083

  1. Go Fly a Kite

    ERIC Educational Resources Information Center

    Klopack, Ken

    2009-01-01

    This article describes an "art kite" activity. The idea is to construct and decorate a non-flying kite that they could display for an art exhibit. Through the activity, students learn to give and take suggestions from one another, improve the quality of their work and set a wonderful atmosphere of collaboration. (Contains 1 online resource.)

  2. Fly-ash utilization

    SciTech Connect

    Lockerby, R.W.

    1984-01-01

    The over 200 references in this bibliography cover some of the uses found for fly-ash, which range from the manufacture of bricks and as a new type of concrete to the recovery of aluminum and other valuable ores from the ash. The entries are grouped under seven headings: General, Agriculture, Brickmaking, Cement/Concrete, Land Reclamation, Resource Recovery, and Other.

  3. Development of a dry-type shunt capacitor

    SciTech Connect

    Grahame, F.W.; Chai, H.M.; Newcomb, G.R.; Reed, C.W.

    1991-11-01

    This report describes the results of a project to determine whether it is feasible to make a liquid-free 200 kVAR, 7200 Vac power factor correction capacitor. After evaluating many solid and gaseous candidate systems, the combination of vapor deposited electrodes on polypropylene sheet dielectric, encapsulated in polyurethane resin was selected. Cell capacitors were used for the initial screening. Next a series of mid size model capacitors were built to evaluate the bushing and the terminal-to-case insulation. Capacitors with vapor deposited electrodes can sometimes generate enough gas at end of life to rupture the case. While no liquid will emerge from a dry capacitor in this situation, there can be a brief jet of flame from an arc. To avoid this, a presence actuated protector device was developed to prevent excess pressure buildup at time of failure. Full size capacitors passed extended life tests, fault tests and radio noise tests. Finally, field trials were run at five widely dispersed installations. The field trials were successful. The present projected cost of dry power capacitors is significantly greater than their liquid counterparts. Future changes in environmental requirements, together with further technical development, may change this situation.

  4. Development of a dry-type shunt capacitor. Final report

    SciTech Connect

    Grahame, F.W.; Chai, H.M.; Newcomb, G.R.; Reed, C.W.

    1991-11-01

    This report describes the results of a project to determine whether it is feasible to make a liquid-free 200 kVAR, 7200 Vac power factor correction capacitor. After evaluating many solid and gaseous candidate systems, the combination of vapor deposited electrodes on polypropylene sheet dielectric, encapsulated in polyurethane resin was selected. Cell capacitors were used for the initial screening. Next a series of mid size model capacitors were built to evaluate the bushing and the terminal-to-case insulation. Capacitors with vapor deposited electrodes can sometimes generate enough gas at end of life to rupture the case. While no liquid will emerge from a dry capacitor in this situation, there can be a brief jet of flame from an arc. To avoid this, a presence actuated protector device was developed to prevent excess pressure buildup at time of failure. Full size capacitors passed extended life tests, fault tests and radio noise tests. Finally, field trials were run at five widely dispersed installations. The field trials were successful. The present projected cost of dry power capacitors is significantly greater than their liquid counterparts. Future changes in environmental requirements, together with further technical development, may change this situation.

  5. GPU-based Multilevel Clustering.

    PubMed

    Chiosa, Iurie; Kolb, Andreas

    2010-04-01

    The processing power of parallel co-processors like the Graphics Processing Unit (GPU) are dramatically increasing. However, up until now only a few approaches have been presented to utilize this kind of hardware for mesh clustering purposes. In this paper we introduce a Multilevel clustering technique designed as a parallel algorithm and solely implemented on the GPU. Our formulation uses the spatial coherence present in the cluster optimization and hierarchical cluster merging to significantly reduce the number of comparisons in both parts . Our approach provides a fast, high quality and complete clustering analysis. Furthermore, based on the original concept we present a generalization of the method to data clustering. All advantages of the meshbased techniques smoothly carry over to the generalized clustering approach. Additionally, this approach solves the problem of the missing topological information inherent to general data clustering and leads to a Local Neighbors k-means algorithm. We evaluate both techniques by applying them to Centroidal Voronoi Diagram (CVD) based clustering. Compared to classical approaches, our techniques generate results with at least the same clustering quality. Our technique proves to scale very well, currently being limited only by the available amount of graphics memory. PMID:20421676

  6. Multilevel Complex Networks and Systems

    NASA Astrophysics Data System (ADS)

    Caldarelli, Guido

    2014-03-01

    Network theory has been a powerful tool to model isolated complex systems. However, the classical approach does not take into account the interactions often present among different systems. Hence, the scientific community is nowadays concentrating the efforts on the foundations of new mathematical tools for understanding what happens when multiple networks interact. The case of economic and financial networks represents a paramount example of multilevel networks. In the case of trade, trade among countries the different levels can be described by the different granularity of the trading relations. Indeed, we have now data from the scale of consumers to that of the country level. In the case of financial institutions, we have a variety of levels at the same scale. For example one bank can appear in the interbank networks, ownership network and cds networks in which the same institution can take place. In both cases the systemically important vertices need to be determined by different procedures of centrality definition and community detection. In this talk I will present some specific cases of study related to these topics and present the regularities found. Acknowledged support from EU FET Project ``Multiplex'' 317532.

  7. Multilevel sequential Monte Carlo samplers

    DOE PAGESBeta

    Beskos, Alexandros; Jasra, Ajay; Law, Kody; Tempone, Raul; Zhou, Yan

    2016-08-24

    Here, we study the approximation of expectations w.r.t. probability distributions associated to the solution of partial differential equations (PDEs); this scenario appears routinely in Bayesian inverse problems. In practice, one often has to solve the associated PDE numerically, using, for instance finite element methods and leading to a discretisation bias, with the step-size level hL. In addition, the expectation cannot be computed analytically and one often resorts to Monte Carlo methods. In the context of this problem, it is known that the introduction of the multilevel Monte Carlo (MLMC) method can reduce the amount of computational effort to estimate expectations, for a given level of error. This is achieved via a telescoping identity associated to a Monte Carlo approximation of a sequence of probability distributions with discretisation levelsmore » $${\\infty}$$ >h0>h1 ...>hL. In many practical problems of interest, one cannot achieve an i.i.d. sampling of the associated sequence of probability distributions. A sequential Monte Carlo (SMC) version of the MLMC method is introduced to deal with this problem. In conclusion, it is shown that under appropriate assumptions, the attractive property of a reduction of the amount of computational effort to estimate expectations, for a given level of error, can be maintained within the SMC context.« less

  8. Development of High Temperature Capacitor Technology and Manufacturing Capability

    SciTech Connect

    None, None

    2011-05-15

    The goal of the Development of High Temperature Capacitor Technology and Manufacturing Capability program was to mature a production-ready supply chain for reliable 250°C FPE (fluorinated polyester) film capacitors by 2011. These high-temperature film capacitors enable both the down hole drilling and aerospace industries by enabling a variety of benefits including: - Deeper oil exploration in higher temperature and pressure environments - Enabling power electronic and control equipment to operate in higher temperature environments - Enabling reduced cooling requirements of electronics - Increasing reliability and life of capacitors operating below rated temperature - Enabling capacitors to handle higher electrical losses without overheating. The key challenges to bringing the FPE film capacitors to market have been manufacturing challenges including: - FPE Film is difficult to handle and wind, resulting in poor yields - Voltage breakdown strength decreases when the film is wound into capacitors (~70% decrease) - Encapsulation technologies must be improved to enable higher perature operation - Manufacturing and test cycle time is very long As a direct result of this program most of the manufacturing challenges have been met. The FPE film production metalization and winding yield has increased to over 82% from 70%, and the voltage breakdown strength of the wound capacitors has increased 270% to 189 V/μm. The high temperature packaging concepts are showing significant progress including promising results for lead attachments and hermetic packages at 200°C and non-hermetic packages at 250°C. Manufacturing and test cycle time will decrease as the market for FPE capacitors develops.

  9. Defibrillation thresholds are lower with smaller storage capacitors.

    PubMed

    Leonelli, F M; Kroll, M W; Brewer, J E

    1995-09-01

    Present implantable cardioverter defibrillators use a wide range of capacitance values for the storage capacitor. However, the optimal capacitance value is unknown. We hypothesized that a smaller capacitor, by delivering its charge in a time closer to the heart chronaxie, should lower the defibrillation threshold (DFT). We compared the energy required to defibrillate 10 open-chest dogs, after 15 seconds of ventricular fibrillation, with a monophasic, time-truncated waveform delivered from either a 85-microF or a 140-microF capacitor. Shocks were delivered through a pair of 14-cm2 epicardial patch electrodes: The two capacitors were randomly tested twice with each dog using a modified 3-reversal method for each DFT determination. The average stored and delivered DFT energies for the 85-microF capacitor were 6.0 +/- 1.7 joules and 5.2 +/- 1.5 joules, respectively, compared to 6.7 +/- 1.7 joules and 6.0 +/- 1.5 joules for the 140-microF capacitor (P = 0.01 and P = 0.004, respectively). The mean leading edge voltages were higher, the pulse duration shorter, and the mean impedance lower for the 85-microF capacitor. The impedance was inversely related to the pulse duration and the voltage decay suggesting that, at least in part, the mechanism of improved defibrillation could be accounted for by the waveform electrical characteristics. There was an equal number of episodes of postshock bradyarrhythmias and tachyarrhythmias following discharges from each capacitor. Moreover, there was no relationship between the likelihood of these arrhythmias and either the initial voltage or the delivered current nor there was a higher number of episodes of postshock hypotension following the smaller capacitor discharges.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7491309

  10. DC-AC Cascaded H-Bridge Multilevel Boost Inverter With No Inductors for Electric/Hybrid Electric Vehicle Applications

    SciTech Connect

    Tolbert, Leon M; Ozpineci, Burak; Du, Zhong; Chiasson, John N

    2009-01-01

    This paper presents a cascaded H-bridge multilevel boost inverter for electric vehicle (EV) and hybrid EV (HEV) applications implemented without the use of inductors. Currently available power inverter systems for HEVs use a dc-dc boost converter to boost the battery voltage for a traditional three-phase inverter. The present HEV traction drive inverters have low power density, are expensive, and have low efficiency because they need a bulky inductor. A cascaded H-bridge multilevel boost inverter design for EV and HEV applications implemented without the use of inductors is proposed in this paper. Traditionally, each H-bridge needs a dc power supply. The proposed design uses a standard three-leg inverter (one leg for each phase) and an H-bridge in series with each inverter leg which uses a capacitor as the dc power source. A fundamental switching scheme is used to do modulation control and to produce a five-level phase voltage. Experiments show that the proposed dc-ac cascaded H-bridge multilevel boost inverter can output a boosted ac voltage without the use of inductors.

  11. An annotated checklist of the horse flies, deer flies, and yellow flies (Diptera: Tabanidae) of Florida

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The family Tabanidae includes the horse flies, deer flies, and yellow flies and is considered a significant pest of livestock throughout the United States, including Florida. Tabanids can easily become a major pest of man, especially salt marsh species which are known to readily feed on humans and o...

  12. Laboratory evaluation of novaluron for controlling larval horn flies, house flies, and stable flies (Diptera: Muscidae)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A granular formulation of novaluron (Novaluron 0.2G, 0.2% AI), a newer benzoylphenyl urea insecticide, was evaluated for its efficacy in controlling the larval stage of horn flies, Haematobia irritans (Linnaeus), house flies, Musca domestica Linnaeus, and stable flies, Stomoxys calcitrans (Linnaeus)...

  13. Challenges facing lithium batteries and electrical double-layer capacitors.

    PubMed

    Choi, Nam-Soon; Chen, Zonghai; Freunberger, Stefan A; Ji, Xiulei; Sun, Yang-Kook; Amine, Khalil; Yushin, Gleb; Nazar, Linda F; Cho, Jaephil; Bruce, Peter G

    2012-10-01

    Energy-storage technologies, including electrical double-layer capacitors and rechargeable batteries, have attracted significant attention for applications in portable electronic devices, electric vehicles, bulk electricity storage at power stations, and "load leveling" of renewable sources, such as solar energy and wind power. Transforming lithium batteries and electric double-layer capacitors requires a step change in the science underpinning these devices, including the discovery of new materials, new electrochemistry, and an increased understanding of the processes on which the devices depend. The Review will consider some of the current scientific issues underpinning lithium batteries and electric double-layer capacitors. PMID:22965900

  14. Local capacitor model for plasmonic electric field enhancement.

    PubMed

    Kang, J H; Kim, D S; Park, Q-Han

    2009-03-01

    We present a local capacitor model that enables a simple yet quantitatively accurate description of lightning rod effect in nanoplasmonics. A notion of lambda-zone capacitance is proposed and applied to predict the strongly induced electric field by a light source near nanoscale metal edges such as metal tip or metal gap. The enhancement factor, calculated from the local capacitor model, shows excellent agreement with more rigorous results. The lambda-zone capacitor allows a blockwise treatment of nano-optical devices and constitutes a basic element of optical nanocircuits. PMID:19392523

  15. Matching properties, and voltage and temperature dependence of MOS capacitors

    NASA Astrophysics Data System (ADS)

    McCreary, J. L.

    1981-12-01

    A technique for designing MOS capacitor arrays is discussed, which includes a method of calculating capacitance ratio errors and subsequent total yield. Data illustrating the sensitivity of the ratio matching to capacitor layout, structures, and technology are presented, and measured voltage coefficients of MOS capacitors as function of surface concentration are compared with the calculated coefficients. It is demonstrated that the temperature dependence of space charge capacitance, thermal expansion, and temperature dependence of the dielectric constant are the major components of the temperature coefficient of capacitance. It is also shown that to a first-order, heavily doped polysilicon accumulates and depletes similar to crystalline silicon.

  16. Negative capacitor paves the way to ultra-broadband metamaterials

    NASA Astrophysics Data System (ADS)

    Hrabar, Silvio; Krois, Igor; Bonic, Ivan; Kiricenko, Aleksandar

    2011-12-01

    Experimental demonstration of the overcoming of basic dispersion-energy constraints in metamaterials with the help of active non-Foster negative capacitors is reported. The experimental metamaterial operates in RF regime, and it is based on air transmission line loaded with negative capacitors. Measurement results clearly show almost dispersionless Epsilon-Near-Zero behavior, accompanied with superluminal both phase and group velocities, over a bandwidth of more than four octaves (2 MHz-40 MHz). The principle of periodic loading of transmission line with negative capacitors may find applications in ultra-broadband active metamaterials for antennas and cloaking technology.

  17. Investigation of Tantalum Wet Slug Capacitor Failures in the Apollo Telescope Mount Charger Battery Regulator Modules

    NASA Technical Reports Server (NTRS)

    Williams, J. F.; Wiedeman, D. H.

    1973-01-01

    This investigation describes the capacitor failures and to identify the cause of the failure mechanism. Early failures were thought to have happened because of age and/or abuse since the failed capacitors were dated 1967. It is shown that all 1967 capacitors were replaced with 1972 capacitors.

  18. A multilevel preconditioner for domain decomposition boundary systems

    SciTech Connect

    Bramble, J.H.; Pasciak, J.E.; Xu, Jinchao.

    1991-12-11

    In this note, we consider multilevel preconditioning of the reduced boundary systems which arise in non-overlapping domain decomposition methods. It will be shown that the resulting preconditioned systems have condition numbers which be bounded in the case of multilevel spaces on the whole domain and grow at most proportional to the number of levels in the case of multilevel boundary spaces without multilevel extensions into the interior.

  19. Multi-level block permutation

    PubMed Central

    Winkler, Anderson M.; Webster, Matthew A.; Vidaurre, Diego; Nichols, Thomas E.; Smith, Stephen M.

    2015-01-01

    Under weak and reasonable assumptions, mainly that data are exchangeable under the null hypothesis, permutation tests can provide exact control of false positives and allow the use of various non-standard statistics. There are, however, various common examples in which global exchangeability can be violated, including paired tests, tests that involve repeated measurements, tests in which subjects are relatives (members of pedigrees) — any dataset with known dependence among observations. In these cases, some permutations, if performed, would create data that would not possess the original dependence structure, and thus, should not be used to construct the reference (null) distribution. To allow permutation inference in such cases, we test the null hypothesis using only a subset of all otherwise possible permutations, i.e., using only the rearrangements of the data that respect exchangeability, thus retaining the original joint distribution unaltered. In a previous study, we defined exchangeability for blocks of data, as opposed to each datum individually, then allowing permutations to happen within block, or the blocks as a whole to be permuted. Here we extend that notion to allow blocks to be nested, in a hierarchical, multi-level definition. We do not explicitly model the degree of dependence between observations, only the lack of independence; the dependence is implicitly accounted for by the hierarchy and by the permutation scheme. The strategy is compatible with heteroscedasticity and variance groups, and can be used with permutations, sign flippings, or both combined. We evaluate the method for various dependence structures, apply it to real data from the Human Connectome Project (HCP) as an example application, show that false positives can be avoided in such cases, and provide a software implementation of the proposed approach. PMID:26074200

  20. Test What You Fly?

    NASA Technical Reports Server (NTRS)

    Margolies, Don

    2002-01-01

    It was the first time on any NASA project I know of that all the instruments on an observatory came off for rework or calibration after the full range of environmental tests, and then were reintegrated at the launch center without the benefit of an observatory environmental retest. Perhaps you've heard the expression, 'Test what you fly, fly what you test'? In theory, it's hard to argue with that. In this case, I was willing to take the risk of not testing what I flew. As the project manager for the Advanced Composition Explorer (ACE) mission, I was the one who ultimately decided what risks to take, just as it was my responsibility to get buy-in from the stakeholders.

  1. Barium titanate nanocomposite capacitor FY09 year end report.

    SciTech Connect

    Stevens, Tyler E.; DiAntonio, Christopher Brian; Yang, Pin; Chavez, Tom P.; Winter, Michael R.; Monson, Todd C.; Roesler, Alexander William; Fellows, Benjamin D.

    2009-11-01

    This late start RTBF project started the development of barium titanate (BTO)/glass nanocomposite capacitors for future and emerging energy storage applications. The long term goal of this work is to decrease the size, weight, and cost of ceramic capacitors while increasing their reliability. Ceramic-based nanocomposites have the potential to yield materials with enhanced permittivity, breakdown strength (BDS), and reduced strain, which can increase the energy density of capacitors and increase their shot life. Composites of BTO in glass will limit grain growth during device fabrication (preserving nanoparticle grain size and enhanced properties), resulting in devices with improved density, permittivity, BDS, and shot life. BTO will eliminate the issues associated with Pb toxicity and volatility as well as the variation in energy storage vs. temperature of PZT based devices. During the last six months of FY09 this work focused on developing syntheses for BTO nanoparticles and firing profiles for sintering BTO/glass composite capacitors.

  2. Absorption Voltages and Insulation Resistance in Ceramic Capacitors with Cracks

    NASA Technical Reports Server (NTRS)

    Teverovsky, Alexander

    2014-01-01

    Time dependence of absorption voltages (V(sub abs)) in different types of low-voltage X5R and X7R ceramic capacitors was monitored for a maximum duration of hundred hours after polarization. To evaluate the effect of mechanical defects on V(sub abs)), cracks in the dielectric were introduced either mechanically or by thermal shock. The maximum absorption voltage, time to roll-off, and the rate of voltage decrease are shown to depend on the crack-related leakage currents and insulation resistance in the parts. A simple model that is based on the Dow equivalent circuit for capacitors with absorption has been developed to assess the insulation resistance of capacitors. Standard measurements of the insulation resistance, contrary to the measurements based on V(sub abs)), are not sensitive to the presence of mechanical defects and fail to reveal capacitors with cracks.

  3. Fringe Capacitance of a Parallel-Plate Capacitor.

    ERIC Educational Resources Information Center

    Hale, D. P.

    1978-01-01

    Describes an experiment designed to measure the forces between charged parallel plates, and determines the relationship among the effective electrode area, the measured capacitance values, and the electrode spacing of a parallel plate capacitor. (GA)

  4. Characteristics of Radio-Frequency Circuits Utilizing Ferroelectric Capacitors

    NASA Technical Reports Server (NTRS)

    Eskridge, Michael; Gui, Xiao; MacLeod, Todd; Ho, Fat D.

    2011-01-01

    Ferroelectric capacitors, most commonly used in memory circuits and variable components, were studied in simple analog radio-frequency circuits such as the RLC resonator and Colpitts oscillator. The goal was to characterize the RF circuits in terms of frequency of oscillation, gain, etc, using ferroelectric capacitors. Frequencies of oscillation of both circuits were measured and studied a more accurate resonant frequency can be obtained using the ferroelectric capacitors. Many experiments were conducted and data collected. A model to simulate the experimental results will be developed. Discrepancies in gain and frequency in these RF circuits when conventional capacitors are replaced with ferroelectric ones were studied. These results will enable circuit designers to anticipate the effects of using ferroelectric components in their radio- frequency applications.

  5. Improvement program for polycarbonate capacitors. [hermetically sealed, and ac wound

    NASA Technical Reports Server (NTRS)

    Bailey, R. R.; Waterman, K. D.

    1973-01-01

    Hermetically sealed, wound, AC, polycarbonate capacitors incorporating design improvements recommended in a previous study were designed and built. A 5000 hour, 400 Hz ac life test was conducted using 384 of these capacitors to verify the adequacy of the design improvements. The improvements incorporated in the capacitors designed for this program eliminated the major cause of failure found in the preceding work, termination failure. A failure cause not present in the previous test became significant in this test with capacitors built from one lot of polycarbonate film. The samples from this lot accounted for 25 percent of the total test complement. Analyses of failed samples showed that the film had an excessive solvent content. This solvent problem was found in 37 of the total 46 failures which occurred in this test. The other nine were random failures resulting from causes such as seal leaks, foreign particles, and possibly wrinkles.

  6. Compact 20-kiloampere pulse-forming-network capacitor bank

    NASA Technical Reports Server (NTRS)

    Posta, S. J.; Michels, C. J.

    1973-01-01

    Bank uses commercially available high-energy-density capacitors for energy storage and silicon-controlled rectifiers for switching. Low voltage design employing solid-state switching is utilized in lieu of conventional gas discharge switching.

  7. Performance comparison: Aluminum electrolytic and solid tantalum capacitor

    NASA Technical Reports Server (NTRS)

    Hawthornthwaite, B. G.; Piper, J.; Holland, H. W.

    1981-01-01

    Several key electrical and environmental parameters of latest technology aluminum electrolytic and solid tantalum capacitors were evaluated in terms of price fluctuations of tantalum metal. Performance differences between solid tantalums and aluminum electrolytics are examined.

  8. Multilevel modeling in psychosomatic medicine research.

    PubMed

    Myers, Nicholas D; Brincks, Ahnalee M; Ames, Allison J; Prado, Guillermo J; Penedo, Frank J; Benedict, Catherine

    2012-01-01

    The primary purpose of this study is to provide an overview of multilevel modeling for Psychosomatic Medicine readers and contributors. The article begins with a general introduction to multilevel modeling. Multilevel regression modeling at two levels is emphasized because of its prevalence in psychosomatic medicine research. Simulated data sets based on some core ideas from the Familias Unidas effectiveness study are used to illustrate key concepts including communication of model specification, parameter interpretation, sample size and power, and missing data. Input and key output files from Mplus and SAS are provided. A cluster randomized trial with repeated measures (i.e., three-level regression model) is then briefly presented with simulated data based on some core ideas from a cognitive-behavioral stress management intervention in prostate cancer. PMID:23107843

  9. Mediation from Multilevel to Structural Equation Modeling

    PubMed Central

    MacKinnon, David P.; Valente, Matthew J.

    2016-01-01

    Background/Aims The purpose of this article is to outline multilevel structural equation modeling (MSEM) for mediation analysis of longitudinal data. The introduction of mediating variables can improve experimental and nonexperimental studies of child growth in several ways as discussed throughout this article. Single-mediator individual-level and multilevel mediation models illustrate several current issues in the estimation of mediation with longitudinal data. The strengths of incorporating structural equation modeling (SEM) with multilevel mediation modeling are described. Summary and Key Messages Longitudinal mediation models are pervasive in many areas of research including child growth. Longitudinal mediation models are ideally modeled as repeated measurements clustered within individuals. Further, the combination of MSEM and SEM provides an ideal approach for several reasons, including the ability to assess effects at different levels of analysis, incorporation of measurement error and possible random effects that vary across individuals. PMID:25413658

  10. Automatic multilevel medical image annotation and retrieval.

    PubMed

    Mueen, A; Zainuddin, R; Baba, M Sapiyan

    2008-09-01

    Image retrieval at the semantic level mostly depends on image annotation or image classification. Image annotation performance largely depends on three issues: (1) automatic image feature extraction; (2) a semantic image concept modeling; (3) algorithm for semantic image annotation. To address first issue, multilevel features are extracted to construct the feature vector, which represents the contents of the image. To address second issue, domain-dependent concept hierarchy is constructed for interpretation of image semantic concepts. To address third issue, automatic multilevel code generation is proposed for image classification and multilevel image annotation. We make use of the existing image annotation to address second and third issues. Our experiments on a specific domain of X-ray images have given encouraging results. PMID:17846834