WorldWideScience

Sample records for matrix parallel-plate capacitors

  1. Fringe Capacitance of a Parallel-Plate Capacitor.

    Science.gov (United States)

    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)

  2. Debye length dependence of the anomalous dynamics of ionic double layers in a parallel plate capacitor

    NARCIS (Netherlands)

    Kortschot, R. J.; Philipse, A. P.; Erné, B. H.

    2014-01-01

    The electrical impedance spectrum of simple ionic solutions is measured in a parallel plate capacitor at small applied ac voltage. The influence of the ionic strength is investigated using several electrolytes at different concentrations in solvents of different dielectric constants. The electric

  3. Parametric electroconvection in a weakly conducting fluid in a horizontal parallel-plate capacitor

    International Nuclear Information System (INIS)

    Kartavykh, N. N.; Smorodin, B. L.; Il’in, V. A.

    2015-01-01

    We study the flows of a nonuniformly heated weakly conducting fluid in an ac electric field of a horizontal parallel-plate capacitor. Analysis is carried out for fluids in which the charge formation is governed by electroconductive mechanism associated with the temperature dependence of the electrical conductivity of the medium. Periodic and chaotic regimes of fluid flow are investigated in the limiting case of instantaneous charge relaxation and for a finite relaxation time. Bifurcation diagrams and electroconvective regimes charts are constructed. The regions where fluid oscillations synchronize with the frequency of the external field are determined. Hysteretic transitions between electroconvection regimes are studied. The scenarios of transition to chaotic oscillations are analyzed. Depending on the natural frequency of electroconvective system and the external field frequency, the transition from periodic to chaotic oscillations can occur via quasiperiodicity, a subharmonic cascade, or intermittence

  4. Parametric electroconvection in a weakly conducting fluid in a horizontal parallel-plate capacitor

    Energy Technology Data Exchange (ETDEWEB)

    Kartavykh, N. N.; Smorodin, B. L., E-mail: bsmorodin@yandex.ru; Il’in, V. A. [Perm State National Research University (Russian Federation)

    2015-07-15

    We study the flows of a nonuniformly heated weakly conducting fluid in an ac electric field of a horizontal parallel-plate capacitor. Analysis is carried out for fluids in which the charge formation is governed by electroconductive mechanism associated with the temperature dependence of the electrical conductivity of the medium. Periodic and chaotic regimes of fluid flow are investigated in the limiting case of instantaneous charge relaxation and for a finite relaxation time. Bifurcation diagrams and electroconvective regimes charts are constructed. The regions where fluid oscillations synchronize with the frequency of the external field are determined. Hysteretic transitions between electroconvection regimes are studied. The scenarios of transition to chaotic oscillations are analyzed. Depending on the natural frequency of electroconvective system and the external field frequency, the transition from periodic to chaotic oscillations can occur via quasiperiodicity, a subharmonic cascade, or intermittence.

  5. A Novel Technique for Design of Ultra High Tunable Electrostatic Parallel Plate RF MEMS Variable Capacitor

    Science.gov (United States)

    Baghelani, Masoud; Ghavifekr, Habib Badri

    2017-12-01

    This paper introduces a novel method for designing of low actuation voltage, high tuning ratio electrostatic parallel plate RF MEMS variable capacitors. It is feasible to achieve ultra-high tuning ratios way beyond 1.5:1 barrier, imposed by pull-in effect, by the proposed method. The proposed method is based on spring strengthening of the structure just before the unstable region. Spring strengthening could be realized by embedding some dimples on the spring arms with the precise height. These dimples shorten the spring length when achieved to the substrate. By the proposed method, as high tuning ratios as 7.5:1 is attainable by only considering four dimple sets. The required actuation voltage for this high tuning ratio is 14.33 V which is simply achievable on-chip by charge pump circuits. Brownian noise effect is also discussed and mechanical natural frequency of the structure is calculated.

  6. Effects of the Particle Size and the Solvent in Printing Inks on the Capacitance of Printed Parallel-Plate Capacitors

    Directory of Open Access Journals (Sweden)

    Sungsik Park

    2016-02-01

    Full Text Available Parallel-plate capacitors were fabricated using a printed multi-layer structure in order to determine the effects of particle size and solvent on the capacitance. The conductive-dielectric-conductive layers were sequentially spun using commercial inks and by intermediate drying with the aid of a masking polymeric layer. Both optical and scanning electron microscopy were used to characterize the morphology of the printed layers. The measured capacitance was larger than the theoretically calculated value when ink with small-sized particles was used as the top plate. Furthermore, the use of a solvent whose polarity was similar to that of the underlying dielectric layer enhanced the penetration and resulted in an increase in capacitance. The functional resistance-capacitance low-pass filter was implemented using printed resistors and capacitors, a process that may be scalable in the future.

  7. Development of parallel-plate-based MEMS tunable capacitors with linearized capacitance–voltage response and extended tuning range

    International Nuclear Information System (INIS)

    Shavezipur, M; Nieva, P; Khajepour, A; Hashemi, S M

    2010-01-01

    This paper presents a design technique that can be used to linearize the capacitance–voltage (C–V) response and extend the tuning range of parallel-plate-based MEMS tunable capacitors beyond that of conventional designs. The proposed technique exploits the curvature of the capacitor's moving electrode which could be induced by either manipulating the stress gradients in the plate's material or using bi-layer structures. The change in curvature generates a nonlinear structural stiffness as the moving electrode undergoes out-of-plane deformation due to the actuation voltage. If the moving plate curvature is tailored such that the capacitance increment is proportional to the voltage increment, then a linear C–V response is obtained. The larger structural resistive force at higher bias voltage also delays the pull-in and increases the maximum tunability of the capacitor. Moreover, for capacitors containing an insulation layer between the two electrodes, the proposed technique completely eliminates the pull-in effect. The experimental data obtained from different capacitors fabricated using PolyMUMPs demonstrate the advantages of this design approach where highly linear C–V responses and tunabilities as high as 1050% were recorded. The design methodology introduced in this paper could be easily extended to for example, capacitive pressure and temperature sensors or infrared detectors to enhance their response characteristics.

  8. Parallel plate detectors

    International Nuclear Information System (INIS)

    Gardes, D.; Volkov, P.

    1981-01-01

    A 5x3cm 2 (timing only) and a 15x5cm 2 (timing and position) parallel plate avalanche counters (PPAC) are considered. The theory of operation and timing resolution is given. The measurement set-up and the curves of experimental results illustrate the possibilities of the two counters [fr

  9. A tandem parallel plate analyzer

    International Nuclear Information System (INIS)

    Hamada, Y.; Fujisawa, A.; Iguchi, H.; Nishizawa, A.; Kawasumi, Y.

    1996-11-01

    By a new modification of a parallel plate analyzer the second-order focus is obtained in an arbitrary injection angle. This kind of an analyzer with a small injection angle will have an advantage of small operational voltage, compared to the Proca and Green analyzer where the injection angle is 30 degrees. Thus, the newly proposed analyzer will be very useful for the precise energy measurement of high energy particles in MeV range. (author)

  10. New high voltage parallel plate analyzer

    International Nuclear Information System (INIS)

    Hamada, Y.; Kawasumi, Y.; Masai, K.; Iguchi, H.; Fujisawa, A.; Abe, Y.

    1992-01-01

    A new modification on the parallel plate analyzer for 500 keV heavy ions to eliminate the effect of the intense UV and visible radiations, is successfully conducted. Its principle and results are discussed. (author)

  11. Capacitors.

    Science.gov (United States)

    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)

  12. A position sensitive parallel plate avalanche counter

    International Nuclear Information System (INIS)

    Lombardi, M.; Tan Jilian; Potenza, R.; D'amico, V.

    1986-01-01

    A position sensitive parallel plate avalanche counter with a distributed constant delay-line-cathode (PSAC) is described. The strips formed on the printed board were served as the cathode and the delay line for readout of signals. The detector (PSAC) was operated in isobutane gas at the pressure range from 10 to 20 torr. The position resolution is better than 1 mm and the time resolution is about 350 ps, for 252 Cf fission-spectrum source

  13. Multipactor saturation in parallel-plate waveguides

    International Nuclear Information System (INIS)

    Sorolla, E.; Mattes, M.

    2012-01-01

    The saturation stage of a multipactor discharge is considered of interest, since it can guide towards a criterion to assess the multipactor onset. The electron cloud under multipactor regime within a parallel-plate waveguide is modeled by a thin continuous distribution of charge and the equations of motion are calculated taking into account the space charge effects. The saturation is identified by the interaction of the electron cloud with its image charge. The stability of the electron population growth is analyzed and two mechanisms of saturation to explain the steady-state multipactor for voltages near above the threshold onset are identified. The impact energy in the collision against the metal plates decreases during the electron population growth due to the attraction of the electron sheet on the image through the initial plate. When this growth remains stable till the impact energy reaches the first cross-over point, the electron surface density tends to a constant value. When the stability is broken before reaching the first cross-over point the surface charge density oscillates chaotically bounded within a certain range. In this case, an expression to calculate the maximum electron surface charge density is found whose predictions agree with the simulations when the voltage is not too high.

  14. Parallel Plate Chambers and their possible use in LHC experiments

    International Nuclear Information System (INIS)

    Arefiev, A.; Bencze, Gy.L.; Bizzeti, A.; Choumilov, E.; Civinini, C.; D'Alessandro, R.; Dajko, G.; Fenyvesi, A.; Ferrando, A.; Fouz, M.C.; Iglesias, A.; Ivochkin, V.; Maggi, F.; Malinin, A.; Martinez-Laso, L.; Meschini, M.; Molnar, J.; Pojidaev, V.; Szoncso, F.; Wulz, C.E.

    1995-01-01

    Present status of Parallel Plate Chambers (PPC) is reviewed. After a description of this detector, results from tests concerning PPC efficiency uniformity, radiation hardness, and behaviour in electromagnetic calorimetry are presented. Some possible utilizations in LHC experiments are mentioned. (orig.)

  15. Angular dependence of the parallel plate ionization chambers of Ipen

    International Nuclear Information System (INIS)

    Albuquerque, M. da P.P.; Caldas, L.

    1989-08-01

    The ionization chambers with parallel plates designed and constructed at IPEN for the dosimetry of soft X-radiation fields were studied in relation to thein angular dependence between O and +- 90 0 . The objective of this study is to verify the chambers response variation for small positioning errors during the field dosimetry used in Radiotherapy. The results were compared with those of commercial parallel plate ionization chambers used as secondary and testiary standards. (author) [pt

  16. Thermally optimum spacing of vertical, natural convection cooled, parallel plates

    Science.gov (United States)

    Bar-Cohen, A.; Rohsenow, W. M.

    Vertical two-dimensional channels formed by parallel plates or fins are a frequently encountered configuration in natural convection cooling in air of electronic equipment. In connection with the complexity of heat dissipation in vertical parallel plate arrays, little theoretical effort is devoted to thermal optimization of the relevant packaging configurations. The present investigation is concerned with the establishment of an analytical structure for analyses of such arrays, giving attention to useful relations for heat distribution patterns. The limiting relations for fully-developed laminar flow, in a symmetric isothermal or isoflux channel as well as in a channel with an insulated wall, are derived by use of a straightforward integral formulation.

  17. Scaling Behavior of Dilute Polymer Solutions Confined between Parallel Plates

    NARCIS (Netherlands)

    Vliet, J.H. van; Luyten, M.C.; Brinke, G. ten

    1992-01-01

    The average size and shape of a polymer coil confined in a slit between two parallel plates depends on the distance L between the plates. On the basis of numerical results, four different regimes can be distingubhed. For large values of L the coil is essentially unconfined. For intermediate values

  18. Non-invasive terahertz field imaging inside parallel plate waveguides

    DEFF Research Database (Denmark)

    Iwaszczuk, Krzysztof; Andryieuski, Andrei; Lavrinenko, Andrei

    2011-01-01

    We present a non-invasive broadband air photonic method of imaging of the electric field of THz pulses propagating inside a tapered parallel plate waveguide. The method is based on field-enhanced second harmonic generation of the fundamental laser beam in an external electric field. We apply...

  19. The suppression of destructive sparks in parallel plate proportional counters

    Energy Technology Data Exchange (ETDEWEB)

    Cockshott, R.A.; Mason, I.M.

    1984-02-01

    The authors find that high energy background events produce localised sparks in parallel plate counters when operated in the proportional mode. These sparks increase dead-time and lead to degradation ranging from electrode damage to spurious pulsing and continuous breakdown. The problem is particularly serious in low energy photon detectors for X-ray astronomy which are required to have lifetimes of several years in the high radiation environment of space. For the parallel plate imaging detector developed for the European X-ray Observatory Satellite (EXOSAT) they investigate quantitatively the spark thresholds, spark rates and degradation processes. They discuss the spark mechanism, pointing out differences from the situation in spark chambers and counters. They show that the time profile of the sparks allows them to devise a spark suppression system which reduces the degradation rate by a factor of ''200.

  20. Two-layer radio frequency MEMS fractal capacitors in PolyMUMPS for S-band applications

    KAUST Repository

    Elshurafa, Amro M.; Salama, Khaled N.

    2012-01-01

    In this Letter, the authors fabricate for the first time MEMS fractal capacitors possessing two layers and compare their performance characteristics with the conventional parallel-plate capacitor and previously reported state-of-the-art single

  1. Rough Electrode Creates Excess Capacitance in Thin-Film Capacitors.

    Science.gov (United States)

    Torabi, Solmaz; Cherry, Megan; Duijnstee, Elisabeth A; Le Corre, Vincent M; Qiu, Li; Hummelen, Jan C; Palasantzas, George; Koster, L Jan Anton

    2017-08-16

    The parallel-plate capacitor equation is widely used in contemporary material research for nanoscale applications and nanoelectronics. To apply this equation, flat and smooth electrodes are assumed for a capacitor. This essential assumption is often violated for thin-film capacitors because the formation of nanoscale roughness at the electrode interface is very probable for thin films grown via common deposition methods. In this work, we experimentally and theoretically show that the electrical capacitance of thin-film capacitors with realistic interface roughness is significantly larger than the value predicted by the parallel-plate capacitor equation. The degree of the deviation depends on the strength of the roughness, which is described by three roughness parameters for a self-affine fractal surface. By applying an extended parallel-plate capacitor equation that includes the roughness parameters of the electrode, we are able to calculate the excess capacitance of the electrode with weak roughness. Moreover, we introduce the roughness parameter limits for which the simple parallel-plate capacitor equation is sufficiently accurate for capacitors with one rough electrode. Our results imply that the interface roughness beyond the proposed limits cannot be dismissed unless the independence of the capacitance from the interface roughness is experimentally demonstrated. The practical protocols suggested in our work for the reliable use of the parallel-plate capacitor equation can be applied as general guidelines in various fields of interest.

  2. Stability of unstably stratified shear flow between parallel plates

    Energy Technology Data Exchange (ETDEWEB)

    Fujimura, Kaoru; Kelly, R E

    1987-09-01

    The linear stability of unstably stratified shear flows between two horizontal parallel plates was investigated. Eigenvalue problems were solved numerically by making use of the expansion method in Chebyshev polynomials, and the critical Rayleigh numbers were obtained accurately in the Reynolds number range of (0.01, 100). It was found that the critical Rayleigh number increases with an increase of the Reynolds number. The result strongly supports previous stability analyses except for the analysis by Makino and Ishikawa (J. Jpn. Soc. Fluid Mech. 4 (1985) 148 - 158) in which a decrease of the critical Rayleigh number was obtained.

  3. Stability of unstably stratified shear flow between parallel plates

    International Nuclear Information System (INIS)

    Fujimura, Kaoru; Kelly, R.E.

    1987-01-01

    The linear stability of unstably stratified shear flows between two horizontal parallel plates was investigated. Eigenvalue problems were solved numerically by making use of the expansion method in Chebyshev polynomials, and the critical Rayleigh numbers were obtained accurately in the Reynolds number range of [0.01, 100]. It was found that the critical Rayleigh number increases with an increase of the Reynolds number. The result strongly supports previous stability analyses except for the analysis by Makino and Ishikawa [J. Jpn. Soc. Fluid Mech. 4 (1985) 148 - 158] in which a decrease of the critical Rayleigh number was obtained. (author)

  4. A model of breakdown in parallel-plate detectors

    International Nuclear Information System (INIS)

    Fonte, P.

    1996-01-01

    Parallel-plate avalanche chambers (PPAC's) have many desirable properties, such as a fast, large area particle detector. However, the maximum gain is limited by a form of violent breakdown that limits the usefulness of this detector, despite its other evident qualities. The exact nature of this phenomenon is not yet sufficiently clear to sustain possible improvements. A previous experimental study is complemented in the present work by a quantitative model of the breakdown phenomenon in PPAC's, based on the streamer theory. The model reproduces well the peculiar behavior of the external current observed in PPAC's and resistive-plate chambers. Other breakdown properties measured in PPAC's are also well reproduced

  5. Performance of a parallel plate volume calorimeter prototype

    International Nuclear Information System (INIS)

    Arefiev, A.; Bencze, Gy.L.; Bizzeti, A.; Choumilov, E.; Civinini, C; D'Alessandro, R.; Ferrando, A.; Fouz, M.C.; Iglesias, A.; Ivochkin, V.; Josa, M.I.; Malinin, A.; Meschini, M.; Misyura, S.; Pojidaev, V.; Salicio, J.M.; Sikler, F.

    1995-01-01

    An iron/gas parallel plate volume calorimeter prototype, working in the avalanche mode, has been tested using electrons of 20 to 150 GeV/c momentum with high voltages varying from 5400 to 5600 V (electric fields ranging from 36 to 37 KV/cm), and a gas mixture of CF4/CO, (80/20%). The collected charge was measured as a function of the high voltage and of the electron energy. The energy resolution was also measured. Comparisons are made with Monte-Carlo predictions. Agreement between data and simulation allows the calculation of the expected performance of a full size calorimeter. (Author)

  6. Performance of a parallel plate volume calorimeter prototype

    International Nuclear Information System (INIS)

    Arefiev, A.; Bencze, G.L.; Bizzeti, A.

    1995-09-01

    An iron/gas parallel plate volume calorimeter prototype, working in the avalanche mode, has been tested using electrons of 20 to 150 GeV/c momentum with high voltages varying from 5400 to 5600 V (electric fields ranging from 36 to 37 KV/cm), and a gas mixture of CF 4 /CO 2 (80/20%). The collected charge was measured as a function of the high voltage and of the electron energy. The energy resolution was also measured. Comparisons are made with Monte-Carlo predictions. Agreement between data and simulation allows the calculation of the expected performance of a full size calorimeter

  7. Systematic test on fast time resolution parallel plate avalanche counter

    International Nuclear Information System (INIS)

    Chen Yu; Li Guangwu; Gu Xianbao; Chen Yanchao; Zhang Gang; Zhang Wenhui; Yan Guohong

    2011-01-01

    Systematic test on each detect unit of parallel plate avalanche counter (PPAC) used in the fission multi-parameter measurement was performed with a 241 Am α source to get the time resolution and position resolution. The detectors work at 600 Pa flowing isobutane and with-600 V on cathode. The time resolution was got by TOF method and the position resolution was got by delay line method. The time resolution of detect units is better than 400 ps, and the position resolution is 6 mm. The results show that the demand of measurement is fully covered. (authors)

  8. A proposed experimental search for chameleons using asymmetric parallel plates

    International Nuclear Information System (INIS)

    Burrage, Clare; Copeland, Edmund J.; Stevenson, James A.

    2016-01-01

    Light scalar fields coupled to matter are a common consequence of theories of dark energy and attempts to solve the cosmological constant problem. The chameleon screening mechanism is commonly invoked in order to suppress the fifth forces mediated by these scalars, sufficiently to avoid current experimental constraints, without fine tuning. The force is suppressed dynamically by allowing the mass of the scalar to vary with the local density. Recently it has been shown that near future cold atoms experiments using atom-interferometry have the ability to access a large proportion of the chameleon parameter space. In this work we demonstrate how experiments utilising asymmetric parallel plates can push deeper into the remaining parameter space available to the chameleon.

  9. A proposed experimental search for chameleons using asymmetric parallel plates

    Energy Technology Data Exchange (ETDEWEB)

    Burrage, Clare; Copeland, Edmund J.; Stevenson, James A., E-mail: Clare.Burrage@nottingham.ac.uk, E-mail: ed.copeland@nottingham.ac.uk, E-mail: james.stevenson@nottingham.ac.uk [School of Physics and Astronomy, University of Nottingham, Nottingham, NG7 2RD (United Kingdom)

    2016-08-01

    Light scalar fields coupled to matter are a common consequence of theories of dark energy and attempts to solve the cosmological constant problem. The chameleon screening mechanism is commonly invoked in order to suppress the fifth forces mediated by these scalars, sufficiently to avoid current experimental constraints, without fine tuning. The force is suppressed dynamically by allowing the mass of the scalar to vary with the local density. Recently it has been shown that near future cold atoms experiments using atom-interferometry have the ability to access a large proportion of the chameleon parameter space. In this work we demonstrate how experiments utilising asymmetric parallel plates can push deeper into the remaining parameter space available to the chameleon.

  10. Improved modelling of a parallel plate active magnetic regenerator

    International Nuclear Information System (INIS)

    Engelbrecht, K; Nielsen, K K; Bahl, C R H; Tušek, J; Kitanovski, A; Poredoš, A

    2013-01-01

    Much of the active magnetic regenerator (AMR) modelling presented in the literature considers only the solid and fluid domains of the regenerator and ignores other physical effects that have been shown to be important, such as demagnetizing fields in the regenerator, parasitic heat losses and fluid flow maldistribution in the regenerator. This paper studies the effects of these loss mechanisms and compares theoretical results with experimental results obtained on an experimental AMR device. Three parallel plate regenerators were tested, each having different demagnetizing field characteristics and fluid flow maldistributions. It was shown that when these loss mechanisms are ignored, the model significantly over predicts experimental results. Including the loss mechanisms can significantly change the model predictions, depending on the operating conditions and construction of the regenerator. The model is compared with experimental results for a range of fluid flow rates and cooling loads. (paper)

  11. Aperture-based antihydrogen gravity experiment: Parallel plate geometry

    Energy Technology Data Exchange (ETDEWEB)

    Rocha, J. R.; Hedlof, R. M.; Ordonez, C. A. [Department of Physics, University of North Texas, Denton, Texas 76203 (United States)

    2013-10-15

    An analytical model and a Monte Carlo simulation are presented of an experiment that could be used to determine the direction of the acceleration of antihydrogen due to gravity. The experiment would rely on methods developed by existing antihydrogen research collaborations. The configuration consists of two circular, parallel plates that have an axis of symmetry directed away from the center of the earth. The plates are separated by a small vertical distance, and include one or more pairs of circular barriers that protrude from the upper and lower plates, thereby forming an aperture between the plates. Antihydrogen annihilations that occur just beyond each barrier, within a “shadow” region, are asymmetric on the upper plate relative to the lower plate. The probability for such annihilations is determined for a point, line and spheroidal source of antihydrogen. The production of 100,000 antiatoms is predicted to be necessary for the aperture-based experiment to indicate the direction of free fall acceleration of antimatter, provided that antihydrogen is produced within a sufficiently small antiproton plasma at a temperature of 4 K.

  12. A parallel plate avalanche chamber for relativistic heavy ions

    International Nuclear Information System (INIS)

    Burgei, R.

    1989-01-01

    In order to determine the interaction point of relativistic heavy ions in the Diogene target, we have built and tested an X-Y low pressure parallel plate avalanche chamber. It uses three thin metallized foils and is filled with isobutane. A preliminary study shows that it is the only detector with the required specifications: efficiency, accurate position determination and a small uniform amount of material for the particle beam to go through. The electronics system is designed for reliability, easy adjustments and high stability. The interaction point is given on delay-line read-out. This represents the optimum compromise between low price and good performance. Laboratory measurements of gain, efficiency and position accuracy are done with an alpha-particle source. Two of these detectors are working at the Saturne National Laboratory. They allow the trajectory of several tens of particles (among a million per second) to be reconstructed. With an argon beam at 400 MeV per nucleon, the position uncertainty in the target has been measured to be 0.5 mm (standard deviation). This uncertainty is 0.3 mm for each detector, with an efficiency of 94 per cent. Our set-up, which is now operational, improves the accuracy of the results and speed of analysis of Diogene experiments devoted to the study of central collisions between heavy ions [fr

  13. Aperture-based antihydrogen gravity experiment: Parallel plate geometry

    Science.gov (United States)

    Rocha, J. R.; Hedlof, R. M.; Ordonez, C. A.

    2013-10-01

    An analytical model and a Monte Carlo simulation are presented of an experiment that could be used to determine the direction of the acceleration of antihydrogen due to gravity. The experiment would rely on methods developed by existing antihydrogen research collaborations. The configuration consists of two circular, parallel plates that have an axis of symmetry directed away from the center of the earth. The plates are separated by a small vertical distance, and include one or more pairs of circular barriers that protrude from the upper and lower plates, thereby forming an aperture between the plates. Antihydrogen annihilations that occur just beyond each barrier, within a "shadow" region, are asymmetric on the upper plate relative to the lower plate. The probability for such annihilations is determined for a point, line and spheroidal source of antihydrogen. The production of 100,000 antiatoms is predicted to be necessary for the aperture-based experiment to indicate the direction of free fall acceleration of antimatter, provided that antihydrogen is produced within a sufficiently small antiproton plasma at a temperature of 4 K.

  14. Aperture-based antihydrogen gravity experiment: Parallel plate geometry

    Directory of Open Access Journals (Sweden)

    J. R. Rocha

    2013-10-01

    Full Text Available An analytical model and a Monte Carlo simulation are presented of an experiment that could be used to determine the direction of the acceleration of antihydrogen due to gravity. The experiment would rely on methods developed by existing antihydrogen research collaborations. The configuration consists of two circular, parallel plates that have an axis of symmetry directed away from the center of the earth. The plates are separated by a small vertical distance, and include one or more pairs of circular barriers that protrude from the upper and lower plates, thereby forming an aperture between the plates. Antihydrogen annihilations that occur just beyond each barrier, within a “shadow” region, are asymmetric on the upper plate relative to the lower plate. The probability for such annihilations is determined for a point, line and spheroidal source of antihydrogen. The production of 100,000 antiatoms is predicted to be necessary for the aperture-based experiment to indicate the direction of free fall acceleration of antimatter, provided that antihydrogen is produced within a sufficiently small antiproton plasma at a temperature of 4 K.

  15. A study of non-ideal focus properties of 30deg parallel plate energy analyzers

    International Nuclear Information System (INIS)

    Fujisawa, A.; Iguchi, H.; Hamada, Y.

    1993-12-01

    A succinct model is proposed to describe non-ideal characteristics owing to electric field penetration into the drift region in actual parallel plate energy analyzers. A good agreement has been obtained between the theoretically expected and experimentally observed focus properties of the 30deg parallel plate analyzer. (author)

  16. Time-resolved terahertz spectroscopy in a parallel-plate waveguide

    DEFF Research Database (Denmark)

    Cooke, David; Jepsen, Peter Uhd

    2009-01-01

    The parallel plate waveguide (PPWG), formed by two conducting parallel plates separated by a distance on the order of the wavelength of the propagating light, has shown itself to be a near ideal terahertz interconnect exhibiting low loss and dispersionless propagation.[1] It is also a useful tool...

  17. Silicon Micropore-Based Parallel Plate Membrane Oxygenator.

    Science.gov (United States)

    Dharia, Ajay; Abada, Emily; Feinberg, Benjamin; Yeager, Torin; Moses, Willieford; Park, Jaehyun; Blaha, Charles; Wright, Nathan; Padilla, Benjamin; Roy, Shuvo

    2018-02-01

    Extracorporeal membrane oxygenation (ECMO) is a life support system that circulates the blood through an oxygenating system to temporarily (days to months) support heart or lung function during cardiopulmonary failure until organ recovery or replacement. Currently, the need for high levels of systemic anticoagulation and the risk for bleeding are main drawbacks of ECMO that can be addressed with a redesigned ECMO system. Our lab has developed an approach using microelectromechanical systems (MEMS) fabrication techniques to create novel gas exchange membranes consisting of a rigid silicon micropore membrane (SμM) support structure bonded to a thin film of gas-permeable polydimethylsiloxane (PDMS). This study details the fabrication process to create silicon membranes with highly uniform micropores that have a high level of pattern fidelity. The oxygen transport across these membranes was tested in a simple water-based bench-top set-up as well in a porcine in vivo model. It was determined that the mass transfer coefficient for the system using SµM-PDMS membranes was 3.03 ± 0.42 mL O 2 min -1 m -2 cm Hg -1 with pure water and 1.71 ± 1.03 mL O 2 min -1 m -2 cm Hg -1 with blood. An analytic model to predict gas transport was developed using data from the bench-top experiments and validated with in vivo testing. This was a proof of concept study showing adequate oxygen transport across a parallel plate SµM-PDMS membrane when used as a membrane oxygenator. This work establishes the tools and the equipoise to develop future generations of silicon micropore membrane oxygenators. © 2017 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

  18. Devices Based on Parallel-Plate Waveguides for Terahertz Applications

    Science.gov (United States)

    Reichel, Kimberly S.

    The promise of terahertz (THz) frequencies for technological applications is wide, spanning from wireless communications for faster downloads to non-destructive imaging for security screening. Although the potential is high, there is a lack of the basic devices necessary to make these prospects a reality. One essential component for any electromagnetic wave technology is a waveguide, which as the name implies can guide light waves, like a hose would direct water from the source to the desired target location. Several waveguide types have been introduced for THz frequencies, one of the most promising of which is the parallel-plate waveguide (PPWG). The PPWG is attractive based on its superior waveguiding performance of efficient input coupling and low losses, but additionally it serves as an excellent platform for other purposes. The projects presented in this dissertation highlight a few new functionalities incorporated into, and enabled by, a PPWG for sensing, filtering, and splitting. First, we characterize a high quality factor resonator integrated into a PPWG used for microfluidic sensing. Typically, the characterization of the frequency-dependent electric field profile inside a narrowband resonator is challenging, either due to limited optical access or to the perturbative effects of invasive probes. In our situation however, the geometry of the PPWG allows for direct access to the resonant cavity via the open sides of the waveguide and a novel implementation of the air-biased coherent detection (ABCD) method permits non-invasive probing. Through both experiment and simulation, we see the narrowband frequencies trapped in the resonator and also discover an unexpected broadband asymmetric field distribution due to the resonator inside the waveguide, yielding new information that is not available in the far field. Second, we investigate a narrowband tunable filter based on extraordinary optical transmission (EOT) through a 1D array of subwavelength holes inside

  19. Analysis of the contribution of sedimentation to bacterial mass transport in a parallel plate flow chamber

    NARCIS (Netherlands)

    Li, Jiuyi; Busscher, Henk J.; Norde, Willem; Sjollema, Jelmer

    2011-01-01

    In order to investigate bacterium-substratum interactions, understanding of bacterial mass transport is necessary. Comparisons of experimentally observed initial deposition rates with mass transport rates in parallel-plate-flow-chambers (PPFC) predicted by convective-diffusion yielded deposition

  20. Experimental and modelling results of a parallel-plate based active magnetic regenerator

    DEFF Research Database (Denmark)

    Tura, A.; Nielsen, Kaspar Kirstein; Rowe, A.

    2012-01-01

    The performance of a permanent magnet magnetic refrigerator (PMMR) using gadolinium parallel plates is described. The configuration and operating parameters are described in detail. Experimental results are compared to simulations using an established twodimensional model of an active magnetic...

  1. Measurement and analysis on dynamic behaviour of parallel-plate assembly in nuclear reactors

    International Nuclear Information System (INIS)

    Chen Junjie; Guo Changqing; Zou Changchuan

    1997-01-01

    Measurement and analysis on dynamic behaviour of parallel-plate assembly in nuclear reactors have been explored. The electromagnetic method, a new method of measuring and analysing dynamic behaviour with the parallel-plate assembly as the structure of multi-parallel-beams joining with single-beam, has been presented. Theoretical analysis and computation results of dry-modal natural frequencies show good agreement with experimental measurements

  2. computational study of Couette flow between parallel plates for steady and unsteady cases

    International Nuclear Information System (INIS)

    Rihan, Y.

    2008-01-01

    Couette flow between parallel plates is a classical problem that has important applications in various industrial processing. In this investigation an analytical solution was obtained to predict the steady and unsteady Couette flow between parallel plates. One of the plates was stationary and the other plate moved with constant velocity. The governing partial differential equations were solved numerically using Crank-Nicolson implicit method to represent the flow behavior of the fluid

  3. Obtaining and electrical characterization of silicone/barium titanate composite for variable capacitor applications; Obtencao e caracterizacao eletrica de composito silicone/titanato de bario para aplicacoes em capacitor variavel

    Energy Technology Data Exchange (ETDEWEB)

    Vieira, D.A.; Souza, P.S.S.; Souza, C.P., E-mail: debora.vieira@cear.ufpb.br [Universidade Federal da Paraiba (UFPB), Joao Pessoa, PB (Brazil). Centro de Energias Alternativas e Renovaveis. Departamento de Engenharia Eletrica; Menezes, P.C.F. [Universidade Federal de Campina Grande (UFCG), Campina Grande, PB (Brazil). Departamento de Engenharia de Materiais

    2014-07-01

    Silicone/barium titanate composites are excellent candidates for applications in the production of electronics components. In this work, silicone/barium titanate composite was obtained for the production of capacitors with variable dielectric distance. The mixture of composite (20% of barium titanate) was performed in a mixer with stem type propellers, at room temperature for 20 minutes. The cure was held in vacuum kiln. After obtaining the composite, was mounted a parallel plate capacitor, using composite as dielectric. The composite obtained was subjected to x-ray diffraction, scanning electron microscopy and capacitive electrical test. The DRX confirms the presence of ceramic charge in composite with the presence of broad peaks of barium titanate and micrographs show the barium titanate particles dispersed in polymer matrix. The capacitance of the sample was approximately 28,7pF. (author)

  4. Improvements to parallel plate flow chambers to reduce reagent and cellular requirements

    Directory of Open Access Journals (Sweden)

    Larson Richard S

    2001-09-01

    Full Text Available Abstract Background The parallel plate flow chamber has become a mainstay for examination of leukocytes under physiologic flow conditions. Several design modifications have occurred over the years, yet a comparison of these different designs has not been performed. In addition, the reagent requirements of many designs prohibit the study of rare leukocyte populations and require large amounts of reagents. Results In this study, we evaluate modifications to a newer parallel plate flow chamber design in comparison to the original parallel plate flow chamber described by Lawrence et al. We show that modifications in the chamber size, internal tubing diameters, injection valves, and a recirculation design may dramatically reduce the cellular and reagent requirements without altering measurements. Conclusions These modifications are simple and easily implemented so that study of rare leukocyte subsets using scarce or expensive reagents can occur.

  5. Current sheet characteristics of a parallel-plate electromagnetic plasma accelerator operated in gas-prefilled mode

    Science.gov (United States)

    Liu, Shuai; Huang, Yizhi; Guo, Haishan; Lin, Tianyu; Huang, Dong; Yang, Lanjun

    2018-05-01

    The axial characteristics of a current sheet in a parallel-plate electromagnetic plasma accelerator operated in gas-prefilled mode are reported. The accelerator is powered by a fourteen stage pulse forming network. The capacitor and inductor in each stage are 1.5 μF and 300 nH, respectively, and yield a damped oscillation square wave of current with a pulse width of 20.6 μs. Magnetic probes and photodiodes are placed at various axial positions to measure the behavior of the current sheet. Both magnetic probe and photodiode signals reveal a secondary breakdown when the current reverses the direction. An increase in the discharge current amplitude and a decrease in pressure lead to a decrease in the current shedding factor. The current sheet velocity and thickness are nearly constant during the run-down phase under the first half-period of the current. The current sheet thicknesses are typically in the range of 25 mm to 40 mm. The current sheet velocities are in the range of 10 km/s to 45 km/s when the discharge current is between 10 kA and 55 kA and the gas prefill pressure is between 30 Pa and 800 Pa. The experimental velocities are about 75% to 90% of the theoretical velocities calculated with the current shedding factor. One reason for this could be that the idealized snowplow analysis model ignores the surface drag force.

  6. Two-layer radio frequency MEMS fractal capacitors in PolyMUMPS for S-band applications

    KAUST Repository

    Elshurafa, Amro M.

    2012-07-23

    In this Letter, the authors fabricate for the first time MEMS fractal capacitors possessing two layers and compare their performance characteristics with the conventional parallel-plate capacitor and previously reported state-of-the-art single-layer MEMS fractal capacitors. Explicitly, a capacitor with a woven structure and another with an interleaved configuration were fabricated in the standard PolyMUMPS surface micromachining process and tested at S-band frequencies. The self-resonant frequencies of the fabricated capacitors were close to 10GHz, which is better than that of the parallel-plate capacitor, which measured only 5.5GHz. Further, the presented capacitors provided a higher capacitance when compared with the state-of-the-art-reported MEMS fractal capacitors created using a single layer at the expense of a lower quality factor. © 2012 The Institution of Engineering and Technology.

  7. Electron equilibrium for parallel plate ionization chambers in gamma radiation fields

    International Nuclear Information System (INIS)

    Caldas, L.; Albuquerque, M. da P.P.

    1989-08-01

    Parallel plate ionization chambers, designed and constructed for use in low energy X-radiation fields, were tested in gamma radiation beams ( 6 Co and 137 Cs) of two different Calibration Laboratories, in order to study the electron equilibrium occurrence and to verify the possibility of their use for the detection of the kind of radiation too. (author) [pt

  8. Calibration of modified parallel-plate rheometer through calibrated oil and lattice Boltzmann simulation

    DEFF Research Database (Denmark)

    Ferraris, Chiara F; Geiker, Mette Rica; Martys, Nicos S

    2007-01-01

    inapplicable here. This paper presents the analysis of a modified parallel plate rheometer for measuring cement mortar and propose a methodology for calibration using standard oils and numerical simulation of the flow. A lattice Boltzmann method was used to simulate the flow in the modified rheometer, thus...

  9. Parallel-plate rheometer calibration using oil and lattice Boltzmann simulation

    DEFF Research Database (Denmark)

    Ferraris, Chiara F; Geiker, Mette Rica; Martys, Nicos S.

    2007-01-01

    compute the viscosity. This paper presents a modified parallel plate rheometer, and proposes means of calibration using standard oils and numerical simulation of the flow. A lattice Boltzmann method was used to simulate the flow in the modified rheometer, thus using an accurate numerical solution in place...

  10. Comparison of electrorheological characteristics obtained for two geometries: parallel plates and concentric cylinders

    Czech Academy of Sciences Publication Activity Database

    Peer, Petra; Filip, Petr; Stěnička, M.; Pavlínek, V.

    2014-01-01

    Roč. 59, č. 3 (2014), s. 221-235 ISSN 0001-7043 R&D Projects: GA ČR(CZ) GAP105/11/2342 Institutional support: RVO:67985874 Keywords : electrorheology * parallel plates * concentric cylinders * silicone oil * PANI powders Subject RIV: BK - Fluid Dynamics

  11. A one-dimensional heat transfer model for parallel-plate thermoacoustic heat exchangers

    NARCIS (Netherlands)

    de Jong, Anne; Wijnant, Ysbrand H.; de Boer, Andries

    2014-01-01

    A one-dimensional (1D) laminar oscillating flow heat transfer model is derived and applied to parallel-plate thermoacoustic heat exchangers. The model can be used to estimate the heat transfer from the solid wall to the acoustic medium, which is required for the heat input/output of thermoacoustic

  12. A simple and accurate method for bidimensional position read-out of parallel plate avalanche counters

    International Nuclear Information System (INIS)

    Breskin, A.; Zwang, N.

    1977-01-01

    A simple method for bidimensional position read-out of Parallel Plate Avalanche counters (PPAC) has been developed, using the induced charge technique. An accuracy better than 0.5 mm (FWHM) has been achieved for both coordinates with 5.5. MeV α-particles at gas pressures of 10-40 torr. (author)

  13. Laminar dispersion in parallel plate sections of flowing systems used in analytical chemistry and chemical engineering

    NARCIS (Netherlands)

    Kolev, S.D.; Kolev, Spas D.; van der Linden, W.E.

    1991-01-01

    An exact solution of the convective-diffusion equation for fully developed parallel plate laminar flow was obtained. It allows the derivation of theoretical relationships for calculating the Peclet number in the axially dispersed plug flow model and the concentration distribution perpendicular to

  14. Analysis of single blow effectiveness in non-uniform parallel plate regenerators

    DEFF Research Database (Denmark)

    Jensen, Jesper Buch; Bahl, Christian Robert Haffenden; Engelbrecht, Kurt

    2011-01-01

    Non-uniform distributions of plate spacings in parallel plate regenerators have been found to induce loss of performance. In this paper, it has been investigated how variations of three geometric parameters (the aspect ratio, the porosity, and the standard deviation of the plate spacing) affects...

  15. A position sensitive parallel plate avalanche fission detector for use in particle induced fission coincidence measurements

    NARCIS (Netherlands)

    Plicht, J. van der

    1980-01-01

    A parallel plate avalanche detector developed for the detection of fission fragments in particle induced fission reactions is described. The active area is 6 × 10 cm2; it is position sensitive in one dimension with a resolution of 2.5 mm. The detector can withstand a count rate of 25000 fission

  16. A theoretical response of the electrostatic parallel plate to constant and low-frequency accelerations

    International Nuclear Information System (INIS)

    Lee, Ki Bang

    2009-01-01

    A theoretical response of an electrostatic gap-closing actuator based on parallel plates to constant and low-frequency accelerations has been derived as a function of the applied acceleration and voltage. The nonlinear equation of motion is obtained in a dimensionless form from the fact that the inertial and damping forces are neglected at a frequency much less than the resonant frequency of the parallel plate, and thereafter the nonlinear equation is solved for the stable inter-plate gap at the acceleration and voltage. From the derived solution, the pull-in acceleration is obtained as a function of the applied voltage, and the pull-in voltage is also expressed as a function of the acceleration. The closed-form solution is validated by comparison with a numerical solution. The theoretical solution is in excellent agreement with the numerical results when the actuator is exposed to a constant acceleration as well as a low-frequency acceleration. The theoretical solution and pull-in acceleration and voltage thus provide guidance to prescribe operational constraints for devices that use the parallel plate actuator and to predict the response of the electrostatic gap-closing parallel plates to constant and low-frequency acceleration

  17. Calorimeter detector consisting of a KMgF3 scintillator and parallel-plate avalanche chamber

    International Nuclear Information System (INIS)

    Buzulutskov, A.F.; Turchanovich, L.K.; Vasil'chenko, V.G.

    1989-01-01

    Scintillations of a KMgF 3 crystal have been detected in the parallel-plate avalanche chamber with a TEA gaseous photocathode, the scintillation signal is shown to be much higher than the direct ionization one. The characteristic properties of the calorimeters on the basis of such structure with electrical and optical readout are discussed. 10 refs.; 4 figs

  18. MHD flow of a dusty viscoelastic liquid through a porous medium between two inclined parallel plates

    International Nuclear Information System (INIS)

    Singh, A.K.; Singh, N.P.

    1996-01-01

    Magnetohydrodynamic flow of a dusty viscoelastic liquid (Oldroyd B-liquid) through a porous medium between two parallel plates inclined to the horizon has been studied. The liquid velocity, dust particle velocity and flux of flow have been obtained. Earlier results have been deduced as particular cases of the present investigation. The physical situation of the motion has been discussed graphically. (author)

  19. Towards measurement of the Casimir force between parallel plates separated at sub-mircon distance

    NARCIS (Netherlands)

    Syed Nawazuddin, M.B.; Lammerink, Theodorus S.J.; Wiegerink, Remco J.; Berenschot, Johan W.; de Boer, Meint J.; Elwenspoek, Michael Curt

    2011-01-01

    Ever since its prediction, experimental investigation of the Casimir force has been of great scientific interest. Many research groups have successfully attempted quantifying the force with different device geometries; however measurement of the Casimir force between parallel plates with sub-micron

  20. First results on irradiation of ceramic parallel plate chambers with gammas and neutrons

    International Nuclear Information System (INIS)

    Arefiev, A.; Bencze, Gy.L.; Bizzeti, A.; Choumilov, E.; Civinini, C.; Dajko, G.; D'Alessandro, R.; Fenyvesi, A.; Ferrando, A.; Fouz, M.C.; Iglesias, A.; Ivochkin, V.; Josa, M.I.; Malinin, A.; Meschini, M.; Molnar, J.; Pojidaev, V.; Salicio, J.M.; Tanko, L.; Vesztergombi, G.

    1996-01-01

    Ceramic parallel plate chambers were irradiated with gamma rays and neutrons. Results on radiation resistance are presented after 60 Mrad gamma and 0.5.10 16 neutrons per cm 2 irradiation of the detector surface. Results of activation analysis of chambers made of two different ceramic materials are also presented. (orig.)

  1. Measurement of the spark probability in single gap parallel plate chambers

    International Nuclear Information System (INIS)

    Arefiev, A.; Bencze, Gy.L.; Choumilov, E.; Civinini, C.; Dalla Santa, F.; D'Alessandro, R.; Ferrando, A.; Fouz, M.C.; Golovkin, V.; Kholodenko, A.; Iglesias, A.; Ivochkin, V.; Josa, M.I.; Malinin, A.; Meschini, M.; Misyura, S.; Pojidaev, V.; Salicio, J.M.

    1996-01-01

    We present results on the measurements of the spark probability with CO 2 and CF 4 /CO 2 (80/20) mixture, at atmospheric pressure, using 1.5 mm gas gap parallel plate chambers, working at a gas gain ranging from 4.5 x 10 2 to 3.3 x 10 4 . (orig.)

  2. The influence of flow maldistribution on the performance of inhomogeneous parallel plate heat exhangers

    DEFF Research Database (Denmark)

    Nielsen, Kaspar Kirstein; Engelbrecht, Kurt; Bahl, Christian R.H.

    2013-01-01

    of 50 random stacks having equal average channel thicknesses with 20 channels each are used to provide a statistical base. The standard deviation of the stacks is varied as are the flow rate (Reynolds number) and the thermal conductivity of the solid heat exchanger material. It is found that the heat...... transfer performance of inhomogeneous stacks of parallel plates may be reduced significantly due to the maldistribution of the fluid flow compared to the ideal homogeneous case. The individual channels experience different flow velocities and this further induces an inter-channel thermal cross talk.......The heat transfer performance of inhomogeneous parallel plate heat exchangers in transient operation is investigated using an established model. A performance parameter, denoted the Nusselt-scaling factor, is used as benchmark and calculated using a well-established single blow technique. A sample...

  3. Absorbed dose calibration factors for parallel-plate chambers in high energy photon beams

    International Nuclear Information System (INIS)

    McEwen, M.R.; Duane, S.; Thomas, R.A.S.

    2002-01-01

    An investigation was carried out into the performance of parallel-plate chambers in 60 Co and MV photon beams. The aim was to derive calibration factors, investigate chamber-to-chamber variability and provide much-needed information on the use of parallel-plate chambers in high-energy X-ray beams. A set of NE2561/NE2611 reference chambers, calibrated against the primary standard graphite calorimeter is used for the dissemination of absorbed dose to water. The parallel-plate chambers were calibrated by comparison with the NPL reference chambers in a water phantom. Two types of parallel-plate chamber were investigated - the NACP -02 and Roos and measurements were made at 60 C0 and 6 linac photon energies (6-19 MV). Calibration factors were derived together with polarity corrections. The standard uncertainty in the calibration of a chamber in terms of absorbed dose to water is estimated to be ±0.75%. The results of the polarity measurements were somewhat confusing. One would expect the correction to be small and previous measurements in electron beams have indicated that there is little variation between chambers of these types. However, some chambers gave unexpectedly large polarity corrections, up to 0.8%. By contrast the measured polarity correction for a NE2611 chamber was less than 0.13% at all energies. The reason for these large polarity corrections is not clear, but experimental error and linac variations have been ruled out. By combining the calibration data for the different chambers it was possible to obtain experimental k Q factors for the two chamber types. It would appear from the data that the variations between chambers of the same type are random and one can therefore define a generic curve for each chamber type. These are presented in Figure 1, together with equivalent data for two cylindrical chamber types - NE2561/NE2611 and NE2571. As can be seen, there is a clear difference between the curves for the cylindrical chambers and those for the

  4. Single-electron pulse-height spectra in thin-gap parallel-plate chambers

    CERN Document Server

    Fonte, Paulo J R; Peskov, Vladimir; Policarpo, Armando

    1999-01-01

    Single-electron pulse-height spectra were measured in 0.6 and 1.2 mm parallel-plate chambers developed for the TOF system of the ALICE /LHC-HI experiment. Mixtures of Ar with ethane, isobutane, and SF/sub 6/ were studied. The observed spectrum shows a clear peak for all gases, suggesting efficient single-electron detection in thin parallel-plate structures. The pulse-height spectrum can be described by the weighted sum of an exponential and a Polya distribution, the Polya contribution becoming more important at higher gains. Additionally, it was found that the maximum gain, above 10/sup 6/, is limited by the appearance of streamers and depends weakly on the gas composition. The suitability of each mixture for single-electron detection is also quantitatively assessed. (8 refs).

  5. Performance of a parallel plate volume cell prototype for a fast iron/gas calorimeter

    International Nuclear Information System (INIS)

    Bizzeti, A.; Civinini, C.; D'alessandro, R.; Ferrando, A.

    1993-01-01

    We present the first test of the application of the parallel plate chamber principles for the design of a very fast and radiation-hard iron/gas sampling calorimeter, suitable for very forward regions in detectors for LBC; based on the use of thick iron plates as electrodes. We have built a one cell prototype consisting of three parallel thick iron plates (117 mn each). Results on efficiencies and mean collected charge for minimum ionizing particles with different gases are presented. (Author)

  6. Electromagnetic pulse coupling through an aperture into a two-parallel-plate region

    Science.gov (United States)

    Rahmat-Samii, Y.

    1978-01-01

    Analysis of electromagnetic-pulse (EMP) penetration via apertures into cavities is an important study in designing hardened systems. In this paper, an integral equation procedure is developed for determining the frequency and consequently the time behavior of the field inside a two-parallel-plate region excited through an aperture by an EMP. Some discussion of the numerical results is also included in the paper for completeness.

  7. Determination of the Townsend primary ionization coefficient using a parallel plate avalanche counter

    International Nuclear Information System (INIS)

    Tsumaki, Koji

    1988-01-01

    Gas multiplication factors were obtained from the observed fast pulse of a parallel plate avalache counter and the Townsend primary ionization coefficients for methane and isobutane were determined from the data over the ranges E/P = 150-228 V/cm·Torr and 183-411 V/cm·Torr, respectively. The results for methane agreed well with the values obtained by Heylen. (author)

  8. Unsteady free convection MHD flow between two heated vertical parallel plates in induced magnetic field

    International Nuclear Information System (INIS)

    Chakraborty, S.; Borkakati, A.K.

    1999-01-01

    An unsteady viscous incompressible free convection flow of an electrically conducting fluid between two heated vertical parallel plates is considered in presence of a uniform magnetic field applied transversely to the flow. The approximate analytical solutions for velocity, induced field and temperature distributions are obtained for small and large magnetic Reynolds number. The skin-friction on the two plates are obtained and plotted graphically. The problem is extended for thermometric case. (author)

  9. An efficient numerical scheme for the simulation of parallel-plate active magnetic regenerators

    DEFF Research Database (Denmark)

    Torregrosa-Jaime, Bárbara; Corberán, José M.; Payá, Jorge

    2015-01-01

    A one-dimensional model of a parallel-plate active magnetic regenerator (AMR) is presented in this work. The model is based on an efficient numerical scheme which has been developed after analysing the heat transfer mechanisms in the regenerator bed. The new finite difference scheme optimally com...... to the fully implicit scheme, the proposed scheme achieves more accurate results, prevents numerical errors and requires less computational effort. In AMR simulations the new scheme can reduce the computational time by 88%....

  10. Characterization of reticulated vitreous carbon foam using a frisch-grid parallel-plate ionization chamber

    Science.gov (United States)

    Edwards, Nathaniel S.; Conley, Jerrod C.; Reichenberger, Michael A.; Nelson, Kyle A.; Tiner, Christopher N.; Hinson, Niklas J.; Ugorowski, Philip B.; Fronk, Ryan G.; McGregor, Douglas S.

    2018-06-01

    The propagation of electrons through several linear pore densities of reticulated vitreous carbon (RVC) foam was studied using a Frisch-grid parallel-plate ionization chamber pressurized to 1 psig of P-10 proportional gas. The operating voltages of the electrodes contained within the Frisch-grid parallel-plate ionization chamber were defined by measuring counting curves using a collimated 241Am alpha-particle source with and without a Frisch grid. RVC foam samples with linear pore densities of 5, 10, 20, 30, 45, 80, and 100 pores per linear inch were separately positioned between the cathode and anode. Pulse-height spectra and count rates from a collimated 241Am alpha-particle source positioned between the cathode and each RVC foam sample were measured and compared to a measurement without an RVC foam sample. The Frisch grid was positioned in between the RVC foam sample and the anode. The measured pulse-height spectra were indiscernible from background and resulted in negligible net count rates for all RVC foam samples. The Frisch grid parallel-plate ionization chamber measurement results indicate that electrons do not traverse the bulk of RVC foam and consequently do not produce a pulse.

  11. Fast risetime one megajoule capacitor bank

    International Nuclear Information System (INIS)

    Markins, D.; Baker, W.L.; Reinovsky, R.E.; Clark, J.G.

    1976-01-01

    A 100 kV, 1.1 MJ capacitor bank for plasma research experiments has been constructed for the Air Force Weapons Laboratory. The system consists of twenty, individual, low inductance capacitor modules, each utilizing a four element switch package approximately 2 meters wide. Each module contains twenty-four ''scyllac'' type 1.85 μF capacitors. A 100 kV output pulse is obtained by charging the top half of each module to +50 kV and the bottom half to -50 kV. A pressurized, low inductance multichannel switch package incorporating four separately triggered elements is designed to fit into the parallel plate transmission line system of the capacitor module. The bank is configured in a cross shape with twenty modules spaced uniformly around the perimeter of a parallel plate transmission line. The transmission line is constructed with 32 mil aluminum and insulated with 60 mils of mylar. The bank is designed to feed an easily replaceable central coaxial load. The entire system has been repeatedly fired at 100 kV with a dummy resistive load and has delivered 2.2 x 10 7 amperes of current with a risetime of 1.1 μsec. The total measured system inductance is 2.2 nH. This system represents a significant advance in the development of reliable, fast, high current capacitor banks

  12. Graphene-based supercapacitors in the parallel-plate electrode configuration: ionic liquids versus organic electrolytes.

    Science.gov (United States)

    Shim, Youngseon; Kim, Hyung J; Jung, Younjoon

    2012-01-01

    Supercapacitors with two single-sheet graphene electrodes in the parallel plate geometry are studied via molecular dynamics (MD) computer simulations. Pure 1-ethyl-3-methylimidazolium tetrafluoroborate (EMI+BF4-) and a 1.1 M solution of EMI+BF4- in acetonitrile are considered as prototypes of room-temperature ionic liquids (RTILs) and organic electrolytes. Electrolyte structure, charge density and associated electric potential are investigated by varying the charges and separation of the two electrodes. Multiple charge layers formed in the electrolytes in the vicinity of the electrodes are found to screen the electrode surface charge almost completely. As a result, the supercapacitors show nearly an ideal electric double layer behavior, i.e., the electric potential exhibits essentially a plateau behavior in the entire electrolyte region except for sharp changes in screening zones very close to the electrodes. Due to its small size and large charge separation, BF4- is considerably more efficient in shielding electrode charges than EMI+. In the case of the acetonitrile solution, acetonitrile also plays an important role by aligning its dipoles near the electrodes; however, the overall screening mainly arises from ions. Because of the disparity of shielding efficiency between cations and anions, the capacitance of the positively-charged anode is significantly larger than that of the negatively-charged cathode. Therefore, the total cell capacitance in the parallel plate configuration is primarily governed by the cathode. Ion conductivity obtained via the Green-Kubo (GK) method is found to be largely independent of the electrode surface charge. Interestingly, EMI+BF4- shows higher GK ion conductivity than the 1.1 M acetonitrile solution between two parallel plate electrodes.

  13. Effects of Complex Structured Anodic Oxide Dielectric Layer Grown in Pore Matrix for Aluminum Capacitor.

    Science.gov (United States)

    Shin, Jin-Ha; Yun, Sook Young; Lee, Chang Hyoung; Park, Hwa-Sun; Suh, Su-Jeong

    2015-11-01

    Anodization of aluminum is generally divided up into two types of anodic aluminum oxide structures depending on electrolyte type. In this study, an anodization process was carried out in two steps to obtain high dielectric strength and break down voltage. In the first step, evaporated high purity Al on Si wafer was anodized in oxalic acidic aqueous solution at various times at a constant temperature of 5 degrees C. In the second step, citric acidic aqueous solution was used to obtain a thickly grown sub-barrier layer. During the second anodization process, the anodizing potential of various ranges was applied at room temperature. An increased thickness of the sub-barrier layer in the porous matrix was obtained according to the increment of the applied anodizing potential. The microstructures and the growth of the sub-barrier layer were then observed with an increasing anodizing potential of 40 to 300 V by using a scanning electron microscope (SEM). An impedance analyzer was used to observe the change of electrical properties, including the capacitance, dissipation factor, impedance, and equivalent series resistance (ESR) depending on the thickness increase of the sub-barrier layer. In addition, the breakdown voltage was measured. The results revealed that dielectric strength was improved with the increase of sub-barrier layer thickness.

  14. A one-dimensional heat transfer model for parallel-plate thermoacoustic heat exchangers.

    Science.gov (United States)

    de Jong, J A; Wijnant, Y H; de Boer, A

    2014-03-01

    A one-dimensional (1D) laminar oscillating flow heat transfer model is derived and applied to parallel-plate thermoacoustic heat exchangers. The model can be used to estimate the heat transfer from the solid wall to the acoustic medium, which is required for the heat input/output of thermoacoustic systems. The model is implementable in existing (quasi-)1D thermoacoustic codes, such as DeltaEC. Examples of generated results show good agreement with literature results. The model allows for arbitrary wave phasing; however, it is shown that the wave phasing does not significantly influence the heat transfer.

  15. ALL-OPTICAL CONTROL OF THZ RADIATION IN PARALLEL PLATE WAVEGUIDES

    DEFF Research Database (Denmark)

    2010-01-01

    The invention relates to control of THz radiation in parallel plate waveguides (PPWG) by forming components in the waveguide by use of optical radiation pulses. Patterns of excited regions induced in the PPWG by an optical excitation pulses changes the electromagnetic properties of the waveguide...... medium in the THz regime, thereby forming transient passive and active components for controlling THz radiation signals. The excitation can be generation of free charge carriers in a semiconductor material in the PPWG, to create metallic regions that form mirrors, lenses or photonic crystal structures......-on-a-chip applications. The optical and THz radiation can be ultrashort pulses with picosecond or femtosecond pulse durations. L...

  16. Transmission line theory for long plasma production by radio frequency discharges between parallel-plate electrodes

    International Nuclear Information System (INIS)

    Nonaka, S.

    1991-01-01

    In order to seek for a radio frequency (RF) eigen-mode of waves in producing a plasma between a pair of long dielectric-covered parallel-plate RF electrodes, this paper analyzed all normal modes propagating along the electrodes by solving Maxwell's equations. The result showed that only an odd surface wave mode will produce the plasma in usual experimental conditions, which will become a basic transmission line theory when use of such long electrodes for on-line mass-production of amorphous silicon solar cells

  17. Analysis of thermal dispersion in an array of parallel plates with fully-developed laminar flow

    International Nuclear Information System (INIS)

    Xu Jiaying; Lu Tianjian; Hodson, Howard P.; Fleck, Norman A.

    2010-01-01

    The effect of thermal dispersion upon heat transfer across a periodic array of parallel plates is studied. Three basic heat transfer problems are addressed, each for steady, fully-developed, laminar fluid flow: (a) transient heat transfer due to an arbitrary initial temperature distribution within the fluid, (b) steady heat transfer with constant heat flux on all plate surfaces, and (c) steady heat transfer with constant wall temperatures. For problems (a) and (b), the effective thermal dispersivity scales with the Peclet number Pe according to 1 + CPe 2 , where the coefficient C is independent of Pe. For problem (c) the coefficient C is a function of Pe.

  18. Analytic Approximate Solutions for Unsteady Two-Dimensional and Axisymmetric Squeezing Flows between Parallel Plates

    Directory of Open Access Journals (Sweden)

    Mohammad Mehdi Rashidi

    2008-01-01

    Full Text Available The flow of a viscous incompressible fluid between two parallel plates due to the normal motion of the plates is investigated. The unsteady Navier-Stokes equations are reduced to a nonlinear fourth-order differential equation by using similarity solutions. Homotopy analysis method (HAM is used to solve this nonlinear equation analytically. The convergence of the obtained series solution is carefully analyzed. The validity of our solutions is verified by the numerical results obtained by fourth-order Runge-Kutta.

  19. An ion beam tracking system based on a parallel plate avalanche counter

    International Nuclear Information System (INIS)

    Carter, I. P.; Ramachandran, K.; Dasgupta, M.; Hinde, D. J.; Rafiei, R.; Luong, D. H.; Williams, E.; Cook, K. J.; McNeil, S.; Rafferty, D. C.; Harding, A. B.; Muirhead, A. G.; Tunningley, T.

    2013-01-01

    A pair of twin position-sensitive parallel plate avalanche counters have been developed at the Australian National University as a tracking system to aid in the further rejection of unwanted beam particles from a 6.5 T super conducting solenoid separator named SOLEROO. Their function is to track and identify each beam particle passing through the detectors on an event-by-event basis. In-beam studies have been completed and the detectors are in successful operation, demonstrating the tracking capability. A high efficiency 512-pixel wide-angle silicon detector array will then be integrated with the tracking system for nuclear reactions studies of radioactive ions. (authors)

  20. Performance of a parallel plate ionization chamber in beta radiation dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Antonio, Patricia L.; Caldas, Linda V.E., E-mail: patrilan@ipen.b, E-mail: lcaldas@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2011-07-01

    A homemade parallel plate ionization chamber with graphite collecting electrode, and developed for use in mammography beams, was tested in relation to its usefulness in beta radiation dosimetry at the Calibration Laboratory of IPEN. Characterization tests of this ionization chamber were performed, using the Sr-90 + Y-90, Kr-85 and Pm-147 sources of a beta secondary standard system. The results of saturation, leakage current, stabilization time, response stability, linearity, angular dependence, and calibration coefficients are within the recommended limits of international recommendations that indicate that this chamber may be used for beta radiation dosimetry. (author)

  1. Performance of a parallel plate ionization chamber in beta radiation dosimetry

    International Nuclear Information System (INIS)

    Antonio, Patricia L.; Caldas, Linda V.E.

    2011-01-01

    A homemade parallel plate ionization chamber with graphite collecting electrode, and developed for use in mammography beams, was tested in relation to its usefulness in beta radiation dosimetry at the Calibration Laboratory of IPEN. Characterization tests of this ionization chamber were performed, using the Sr-90 + Y-90, Kr-85 and Pm-147 sources of a beta secondary standard system. The results of saturation, leakage current, stabilization time, response stability, linearity, angular dependence, and calibration coefficients are within the recommended limits of international recommendations that indicate that this chamber may be used for beta radiation dosimetry. (author)

  2. Design and analysis of all-dielectric broadband nonpolarizing parallel-plate beam splitters.

    Science.gov (United States)

    Wang, Wenliang; Xiong, Shengming; Zhang, Yundong

    2007-06-01

    Past research on the all-dielectric nonpolarizing beam splitter is reviewed. With the aid of the needle thin-film synthesis method and the conjugate graduate refine method, three different split ratio nonpolarizing parallel-plate beam splitters over a 200 nm spectral range centered at 550 nm with incidence angles of 45 degrees are designed. The chosen materials component and the initial stack are based on the Costich and Thelen theories. The results of design and analysis show that the designs maintain a very low polarization ratio in the working range of the spectrum and has a reasonable angular field.

  3. Conjugated heat transfer in laminar flow between parallel-plates channel

    International Nuclear Information System (INIS)

    Guedes, R.O.C.; Cotta, R.M.; Brum, N.C.L.

    1989-01-01

    An analysis is made of conjugated convective-conductive heat transfer in laminar flow of a newtonian fluid between parallel-plates channel, taking into account the longitudinal conduction along the duct walls only, by neglecting the transversal temperature gradients in the solid. This extended Graetz-type problem is then analytically handled through the generalized integral transform technique, providing accurate numerical results for quantities of practical interest sucyh as bulk and wall temperatures, and Nusselt numbers. The effects of a conjugation parameter and Biot number on heat transfer behavior are then investigated. (author)

  4. Performance of a parallel plate volume cell prototype for a fast iron/gas calorimeter

    Energy Technology Data Exchange (ETDEWEB)

    Bizzeti, A.; Civinini, C.; D' Alessandro, R.; Ferrando, A.; Malinin, A.; Martinez-Laso, L.; Pojidaev, V.

    1993-07-01

    We present the first test of the application of the parallel plate chamber principles for the design of a very fast and radiation-hard iron/gas sampling calorimeter, suitable for very forward regions in detectors for LHC, based on the use of thick iron plates as electrodes. We have built a one cell prototype consisting of three parallel thick iron plates (17 mm each). Results on efficiencies and mean collected charge for minimum ionizing particles with different gases are presented. (Author) 7 refs.

  5. A numerical analysis of a reciprocating Active Magnetic Regenerator with a parallel-plate regenerator geometry

    DEFF Research Database (Denmark)

    Petersen, Thomas Frank; Pryds, Nini; Smith, Anders

    2007-01-01

    We have developed a two-dimensional model of a reciprocating Active Magnetic Regenerator(AMR) with a regenerator made of parallel plates arranged in a stack configuration. The time dependent,two-dimensional model solves the Navier-Stokes equations for the heat transfer fluid and the coupled heat...... transfer equations for the regenerator and the fluid. The model is implemented using the Finite Element Method. The model can be used to study both transient and steady-state phenomena in the AMR for any ratio of regenerator to fluid heat capacity. Results on the AMR performance for different design...

  6. Performance of a parallel plate volume cell prototype for a fast iron/gas calorimeter

    International Nuclear Information System (INIS)

    Bizzeti, A.; Civinini, C.; D'Alessandro, R.; Ferrando, A.; Malinin, A.; Martinez-Laso, L.; Pojidaev, V.

    1993-01-01

    We present the first test of the application of the parallel plate chamber principles for the design of a very fast and radiation-hard iron/gas sampling calorimeter, suitable for very forward regions in detectors for LHC, based on the use of thick iron plates as electrodes. We have built a one cell prototype consisting of three parallel thick iron plates (17 mm each). Results on efficiencies and mean collected charge for minimum ionizing particles with different gases are presented. (Author) 7 refs

  7. The electrical MHD and Hall current impact on micropolar nanofluid flow between rotating parallel plates

    Science.gov (United States)

    Shah, Zahir; Islam, Saeed; Gul, Taza; Bonyah, Ebenezer; Altaf Khan, Muhammad

    2018-06-01

    The current research aims to examine the combined effect of magnetic and electric field on micropolar nanofluid between two parallel plates in a rotating system. The nanofluid flow between two parallel plates is taken under the influence of Hall current. The flow of micropolar nanofluid has been assumed in steady state. The rudimentary governing equations have been changed to a set of differential nonlinear and coupled equations using suitable similarity variables. An optimal approach has been used to acquire the solution of the modelled problems. The convergence of the method has been shown numerically. The impact of the Skin friction on velocity profile, Nusslet number on temperature profile and Sherwood number on concentration profile have been studied. The influences of the Hall currents, rotation, Brownian motion and thermophoresis analysis of micropolar nanofluid have been mainly focused in this work. Moreover, for comprehension the physical presentation of the embedded parameters that is, coupling parameter N1 , viscosity parameter Re , spin gradient viscosity parameter N2 , rotating parameter Kr , Micropolar fluid constant N3 , magnetic parameter M , Prandtl number Pr , Thermophoretic parameter Nt , Brownian motion parameter Nb , and Schmidt number Sc have been plotted and deliberated graphically.

  8. α spectrometer of parallel plate grid ionization chamber of high energy resolution

    International Nuclear Information System (INIS)

    Tong Boting; Wang Jianqing; Dong Mingli; Tang Peijia; Wang Xiaorong; Lin Cansheng

    2000-01-01

    Parallel plate grid ionization chamber with cathode area of 300 cm 2 was developed and applied to detect minimum α-emitters. It consist of a vacuum system, a gas cycle system of the parallel plate grid ionization chamber, electronics (a high voltage supply, a pre-amplifier and a main amplifier) and a computer-multichannel analyzer. The energy resolution is 23 keV FWHM for the 244 Cm electrostatic precipitated source. The integral background is typically 10 counts/h between 4 and 6 MeV. The detector efficiency is 50%. The minimum detecting activity is 3 x 10 -4 Bq (3σ, 30 hours). This spectrometer is suitable for detecting various samples, such as samples of the soil, water, air, bion, food, structural material, geology, archaeology, α-emitters of after processing and measuring α activity of accounting for and control of nuclear material and monitoring the artificial radioactivity nuclides of environment samples around nuclear facilities. The spectrometer is equipped with apparatus for preparing large area α source by using vacuum deposition or ultrasonic pulverization. The operating program of preparing source is simple. The source thickness can be kept in 40-60 μm/cm 2

  9. Study of talcum charging status in parallel plate electrostatic separator based on particle trajectory analysis

    Science.gov (United States)

    Yunxiao, CAO; Zhiqiang, WANG; Jinjun, WANG; Guofeng, LI

    2018-05-01

    Electrostatic separation has been extensively used in mineral processing, and has the potential to separate gangue minerals from raw talcum ore. As for electrostatic separation, the particle charging status is one of important influence factors. To describe the talcum particle charging status in a parallel plate electrostatic separator accurately, this paper proposes a modern images processing method. Based on the actual trajectories obtained from sequence images of particle movement and the analysis of physical forces applied on a charged particle, a numerical model is built, which could calculate the charge-to-mass ratios represented as the charging status of particle and simulate the particle trajectories. The simulated trajectories agree well with the experimental results obtained by images processing. In addition, chemical composition analysis is employed to reveal the relationship between ferrum gangue mineral content and charge-to-mass ratios. Research results show that the proposed method is effective for describing the particle charging status in electrostatic separation.

  10. Development of a parallel plate proportional counter TRD with suppressed sensitivity to ionization

    International Nuclear Information System (INIS)

    Solomey, N.; Krolak, P.; Graham, G.

    1995-01-01

    The development of a Parallel Plate Proportional Counter which has a highly suppressed sensitivity to ionization but retains a good X-ray signal to noise ratio is presented. Details of the laboratory development and actual beam tests showing the e/π rejection are described. Because of its insensitivity to ionization this type of detector can be useful in an environment where the number of minimum ionizing particles are high, but uninteresting; however, the detector is very sensitive to the highly localized electron cloud from converted X-rays making it ideal as a transition radiation X-ray detector. Thus, this detector only gives a signal for charged particles above TR threshold; all other particles below this threshold produce no TR X-rays giving only a pedestal-like signal. The system's potential performance for π/p separation in the intended neutral Hyperon experiment is evaluated

  11. Interaction between two parallel plates covered with a polyelectrolyte brush layer in an electrolyte solution.

    Science.gov (United States)

    Ohshima, Hiroyuki

    An approximate analytic expression is derived for the interaction energy between two parallel plates covered with a polyelectrolyte brush layer in an electrolyte solution. The interaction energy has three components: electrostatic interaction energy between two brush layers before and after their contact, steric interaction energy between two brush layers after their contact, and the van der Waals interaction energy between the cores of the plates. It is shown that these three components are of the same order of magnitude and contribute equally to the total interaction energy between two polyelectrolyte-coated plates in an electrolyte solution. On the basis of Derjaguin's approximation, an approximate expression for the interaction energy between two spherical particles covered with polyelectrolyte brush layers is also derived.

  12. Tunable THz notch filter with a single groove inside parallel-plate waveguides.

    Science.gov (United States)

    Lee, Eui Su; Jeon, Tae-In

    2012-12-31

    A single groove in a parallel-plate waveguide (PPWG) has been applied to a tunable terahertz (THz) notch filter with a transverse-electromagnetic (TEM) mode. When the air gap between the metal plates of the PPWG is controlled from 60 to 240 μm using a motor controlled translation stage or a piezo-actuator, the resonant frequency of the notch filter is changed from 1.75 up to 0.62 THz, respectively. Therefore, the measured tunable sensitivity of the notch filter increases to 6.28 GHz/μm. The measured resonant frequencies were found to be in good agreement with the calculation using an effective groove depth. Using a finite-difference time-domain (FDTD) simulation, we also demonstrate that the sensitivity of a THz microfluidic sensor can be increased via a small air gap, a narrow groove width, and a deep groove depth.

  13. Measurement of the Microwave Refractive Index of Materials Based on Parallel Plate Waveguides

    Science.gov (United States)

    Zhao, F.; Pei, J.; Kan, J. S.; Zhao, Q.

    2017-12-01

    An electrical field scanning apparatus based on a parallel plate waveguide method is constructed, which collects the amplitude and phase matrices as a function of the relative position. On the basis of such data, a method for calculating the refractive index of the measured wedge samples is proposed in this paper. The measurement and calculation results of different PTFE samples reveal that the refractive index measured by the apparatus is substantially consistent with the refractive index inferred with the permittivity of the sample. The proposed refractive index calculation method proposed in this paper is a competitive method for the characterization of the refractive index of materials with positive refractive index. Since the apparatus and method can be used to measure and calculate arbitrary direction of the microwave propagation, it is believed that both of them can be applied to the negative refractive index materials, such as metamaterials or “left-handed” materials.

  14. Casimir effect of two conducting parallel plates in a general weak gravitational field

    Energy Technology Data Exchange (ETDEWEB)

    Nazari, Borzoo [University of Tehran, Faculty of Engineering Science, College of Engineering, P.O. Box 11155-4563, Tehran (Iran, Islamic Republic of)

    2015-10-15

    We calculate the finite vacuum energy density of the scalar and electromagnetic fields inside a Casimir apparatus made up of two conducting parallel plates in a general weak gravitational field. The metric of the weak gravitational field has a small deviation from flat spacetime inside the apparatus, and we find it by expanding the metric in terms of small parameters of the weak background. We show that the metric found can be transformed via a gauge transformation to the Fermi metric. We solve the Klein-Gordon equation exactly and find mode frequencies in Fermi spacetime. Using the fact that the electromagnetic field can be represented by two scalar fields in the Fermi spacetime, we find general formulas for the energy density and mode frequencies of the electromagnetic field. Some well-known weak backgrounds are examined and consistency of the results with the literature is shown. (orig.)

  15. Oscillatory electroosmotic flow in a parallel-plate microchannel under asymmetric zeta potentials

    Science.gov (United States)

    Peralta, M.; Arcos, J.; Méndez, F.; Bautista, O.

    2017-06-01

    In this work, we conduct a theoretical analysis of the start-up of an oscillatory electroosmotic flow (EOF) in a parallel-plate microchannel under asymmetric zeta potentials. It is found that the transient evolution of the flow field is controlled by the parameters {R}ω , {R}\\zeta , and \\bar{κ }, which represent the dimensionless frequency, the ratio of the zeta potentials of the microchannel walls, and the electrokinetic parameter, which is defined as the ratio of the microchannel height to the Debye length. The analysis is performed for both low and high zeta potentials; in the former case, an analytical solution is derived, whereas in the latter, a numerical solution is obtained. These solutions provide the fundamental characteristics of the oscillatory EOFs for which, with suitable adjustment of the zeta potential and the dimensionless frequency, the velocity profiles of the fluid flow exhibit symmetric or asymmetric shapes.

  16. Stratified steady and unsteady two-phase flows between two parallel plates

    International Nuclear Information System (INIS)

    Sim, Woo Gun

    2006-01-01

    To understand fluid dynamic forces acting on a structure subjected to two-phase flow, it is essential to get detailed information about the characteristics of two-phase flow. Stratified steady and unsteady two-phase flows between two parallel plates have been studied to investigate the general characteristics of the flow related to flow-induced vibration. Based on the spectral collocation method, a numerical approach has been developed for the unsteady two-phase flow. The method is validated by comparing numerical result to analytical one given for a simple harmonic two-phase flow. The flow parameters for the steady two-phase flow, such as void fraction and two-phase frictional multiplier, are evaluated. The dynamic characteristics of the unsteady two-phase flow, including the void fraction effect on the complex unsteady pressure, are illustrated

  17. Motion of Charged Suspended Particle in a Non-Newtonian Fluid between Two Long Parallel Plated

    International Nuclear Information System (INIS)

    Abd-El Khalek, M.M.

    1998-01-01

    The motion of charged suspended particle in a non-Newtonian fluid between two long parallel plates is discussed. The equation of motion of a suspended particle was suggested by Closkin. The equations of motion are reduced to ordinary differential equations by similarity transformations and solved numerically by using the Runge-Kutta method. The trajectories of particles are calculated by integrating the equation of motion of a single particle. The present simulation requires some empirical parameters concerning the collision of the particles with the wall. The effects of solid particles on flow properties are discussed. Some typical results for both fluid and particle phases and density distributions of the particles are presented graphically

  18. Motion of charged suspended particle in a non-Newtonian fluid between two long parallel plates

    Energy Technology Data Exchange (ETDEWEB)

    Abd Elkhalek, M M [Nuclear Research Center-Atomic Energy Authority, Cairo (Egypt)

    1997-12-31

    The motion of charged suspended particle in a non-Newtonian fluid between two long parallel plates is discussed. The equation of motion of a suspended particle was suggested by Closkin. The equations of motion are reduced to ordinary differential equations by similarity transformation and solved numerically by using Runge-Kutta method. The trajectories of particles are calculated by integrating the equation of motion of a single particle. The present simulation requires some empirical parameters concerning the collision of the particles with the wall. The effect of solid particles on flow properties are discussed. Some typical results for both fluid and particle phases and density distributions of the particles are presented graphically. 4 figs.

  19. Unsteady MHD blood flow through porous medium in a parallel plate channel

    Science.gov (United States)

    Latha, R.; Rushi Kumar, B.

    2017-11-01

    In this study, we have analyzed heat and mass transfer effects on unsteady blood flow through parallel plate channel in a saturated porous medium in the presence of a transverse magnetic field with thermal radiation. The governing higher order nonlinear PDE’S are converted to dimensionless equations using dimensionless variables. The dimensionless equations are then solved analytically using boundary conditions by choosing the axial flow transport and the fields of concentration and temperature apart from the normal velocity as a function of y and t. The effects of different pertinent parameters appeared in this model viz thermal radiation, Prandtl number, Heat source parameter, Hartmann number, Permeability parameter, Decay parameter on axial flow transport and the normal velocity are analyzed in detail.

  20. Electron beam test of an iron/gas calorimeter based on ceramic parallel plate chambers

    International Nuclear Information System (INIS)

    Arefiev, A.; Bencze, Gy.L.; Bizzeti, A.; Choumilov, E.; Civinini, C; Dalla Santa, F.; D'Alessandro, R.; Ferrando, A.; Fouz, M.C.; Herve, A.; Iglesias, A.; Ivochkin, V.; Josa, M.I.; Maggi, F.; Malinin, A.; Meschini, M.; Pojidaev, V.; Radermacher, E.; Salicio, J.M.

    1995-01-01

    The baseline option for the very forward calorimetry in the CMS experiment is an iron/gas calorimeter based on parallel plate chambers. A small prototype module of such a calorimeter, has been tested using electrons of 5 to 100 GeV/c momentum with various high voltages and two gases: CO2 (100%) and CF4/CO2 (80/20), at atmospheric pressure. The collected charge has been measured as a function of the high voltage and of the electron energy. The energy resolution has also been measured. Comparisons have been made with Monte-Carlo predictions. Agreement between data an simulation allows to make and estimation of the expected performance of a full size calorimeter. (Author) 23 refs

  1. Electron beam test of an iron/gas calorimeter based on ceramic parallel plate chambers

    International Nuclear Information System (INIS)

    Arefiev, A.; Bencze, G.L.; Bizzeti, A.; choumilov, E.; Civinini, C.; Dalla Santa, F.; D'Alessandro, R.; Ferrando, A.; Fouz, M.C.; Herve, A.; Iglesias, A.; Ivochkin, V.; Josa, M.I.; Maggi, F.; Malininin, A.; Meschini, M.; Pojidaev, V.; Radermacher, E.; Salicio, J.M.

    1995-12-01

    The baseline option for the very forward calorimetry in the CMS experiment is an iron/gas calorimeter based on parallel plate chambers. A small prototype module of such a calorimeter, has been tested using electrons of 5 to 100 GeV/c momentum with various high voltages and two gases: CO 2 (100%) and CF 4 /CO 2 (80/20), at atmospheric pressure. The collected charge has been measured as a function of the high voltage and of the electron energy. The energy resolution has also been measured. Comparisons have been made with Monte-Carlo predictions. Agreement between data an simulation allows to make and estimation of the expected performance of a full size calorimeter. (Author)

  2. Computational Fluid Dynamic Pressure Drop Estimation of Flow between Parallel Plates

    Energy Technology Data Exchange (ETDEWEB)

    Son, Hyung Min; Yang, Soo Hyung; Park, Jong Hark [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2014-10-15

    Many pool type reactors have forced downward flows inside the core during normal operation; there is a chance of flow inversion when transients occur. During this phase, the flow undergo transition between turbulent and laminar regions where drastic changes take place in terms of momentum and heat transfer, and the decrease in safety margin is usually observed. Additionally, for high Prandtl number fluids such as water, an effect of the velocity profile inside the channel on the temperature distribution is more pronounced over the low Prandtl number ones. This makes the checking of its pressure drop estimation accuracy less important, assuming the code verification is complete. With an advent of powerful computer hardware, engineering applications of computational fluid dynamics (CFD) methods have become quite common these days. Especially for a fully-turbulent and single phase convective heat transfer, the predictability of the commercial codes has matured enough so that many well-known companies adopt those to accelerate a product development cycle and to realize an increased profitability. In contrast to the above, the transition models for the CFD code are still under development, and the most of the models show limited generality and prediction accuracy. Unlike the system codes, the CFD codes estimate the pressure drop from the velocity profile which is obtained by solving momentum conservation equations, and the resulting friction factor can be a representative parameter for a constant cross section channel flow. In addition, the flow inside a rectangular channel with a high span to gap ratio can be approximated by flow inside parallel plates. The computational fluid dynamics simulation on the flow between parallel plates showed reasonable prediction capability for the laminar and the turbulent regime.

  3. Matching Properties of Femtofarad and Sub-Femtofarad MOM Capacitors

    KAUST Repository

    Omran, Hesham

    2016-04-21

    Small metal-oxide-metal (MOM) capacitors are essential to energy-efficient mixed-signal integrated circuit design. However, only few reports discuss their matching properties based on large sets of measured data. In this paper, we report matching properties of femtofarad and sub-femtofarad MOM vertical-field parallel-plate capacitors and lateral-field fringing capacitors. We study the effect of both the finger-length and finger-spacing on the mismatch of lateral-field capacitors. In addition, we compare the matching properties and the area efficiency of vertical-field and lateral-field capacitors. We use direct mismatch measurement technique, and we illustrate its feasibility using experimental measurements and Monte Carlo simulations. The test-chips are fabricated in a 0.18 \\\\mutext{m} CMOS process. A large number of test structures is characterized (4800 test structures), which improves the statistical reliability of the extracted mismatch information. Despite conventional wisdom, extensive measurements show that vertical-field and lateral-field MOM capacitors have the same matching properties when the actual capacitor area is considered. Measurements show that the mismatch depends on the capacitor area but not on the spacing; thus, for a given mismatch specification, the lateral-field MOM capacitor can have arbitrarily small capacitance by increasing the spacing between the capacitor fingers, at the expense of increased chip area.

  4. Matching Properties of Femtofarad and Sub-Femtofarad MOM Capacitors

    KAUST Repository

    Omran, Hesham; Alahmadi, Hamzah; Salama, Khaled N.

    2016-01-01

    Small metal-oxide-metal (MOM) capacitors are essential to energy-efficient mixed-signal integrated circuit design. However, only few reports discuss their matching properties based on large sets of measured data. In this paper, we report matching properties of femtofarad and sub-femtofarad MOM vertical-field parallel-plate capacitors and lateral-field fringing capacitors. We study the effect of both the finger-length and finger-spacing on the mismatch of lateral-field capacitors. In addition, we compare the matching properties and the area efficiency of vertical-field and lateral-field capacitors. We use direct mismatch measurement technique, and we illustrate its feasibility using experimental measurements and Monte Carlo simulations. The test-chips are fabricated in a 0.18 \\mutext{m} CMOS process. A large number of test structures is characterized (4800 test structures), which improves the statistical reliability of the extracted mismatch information. Despite conventional wisdom, extensive measurements show that vertical-field and lateral-field MOM capacitors have the same matching properties when the actual capacitor area is considered. Measurements show that the mismatch depends on the capacitor area but not on the spacing; thus, for a given mismatch specification, the lateral-field MOM capacitor can have arbitrarily small capacitance by increasing the spacing between the capacitor fingers, at the expense of increased chip area.

  5. Differential RF MEMS interwoven capacitor immune to residual stress warping

    KAUST Repository

    Elshurafa, Amro M.; Salama, Khaled N.

    2012-01-01

    A RF MEMS capacitor with an interwoven structure is designed, fabricated in the PolyMUMPS process and tested in an effort to address fabrication challenges usually faced in MEMS processes. The interwoven structure was found to offer several advantages over the typical MEMS parallel-plate design including eliminating the warping caused by residual stress, eliminating the need for etching holes, suppressing stiction, reducing parasitics and providing differential capability. The quality factor of the proposed capacitor was higher than five throughout a 2–10 GHz range and the resonant frequency was in excess of 20 GHz.

  6. Differential RF MEMS interwoven capacitor immune to residual stress warping

    KAUST Repository

    Elshurafa, Amro M.

    2012-07-27

    A RF MEMS capacitor with an interwoven structure is designed, fabricated in the PolyMUMPS process and tested in an effort to address fabrication challenges usually faced in MEMS processes. The interwoven structure was found to offer several advantages over the typical MEMS parallel-plate design including eliminating the warping caused by residual stress, eliminating the need for etching holes, suppressing stiction, reducing parasitics and providing differential capability. The quality factor of the proposed capacitor was higher than five throughout a 2–10 GHz range and the resonant frequency was in excess of 20 GHz.

  7. Early biofilm formation and the effects of antimicrobial agents on orthodontic bonding materials in a parallel plate flow chamber

    NARCIS (Netherlands)

    Chin, Yeen; Busscher, HJ; Evans, R; Noar, J; Pratten, J

    Decalcification is a commonly recognized complication of orthodontic treatment with fixed appliances. A technology, based on a parallel plate flow chamber, was developed to investigate early biofilm formation of a strain of Streptococcus sanguis on the surface of four orthodontic bonding materials:

  8. DEVELOPMENT AND USE OF A PARALLEL-PLATE FLOW CHAMBER FOR STUDYING CELLULAR ADHESION TO SOLID-SURFACES

    NARCIS (Netherlands)

    VANKOOTEN, TG; SCHAKENRAAD, JM; VANDERMEI, HC; BUSSCHER, HJ

    A parallel-plate flow chamber is developed in order to study cellular adhesion phenomena. An image analysis system is used to observe individual cells exposed to flow in situ and to determine area, perimeter, and shape of these cells as a function of time and shear stress. With this flow system the

  9. Air bubble-induced detachment of polystyrene particles with different sizes from collector surfaces in a parallel plate flow chamber

    NARCIS (Netherlands)

    Gomez-Suarez, C; van der Mei, HC; Busscher, HJ

    2001-01-01

    Particle size was found to be an important factor in air bubble-induced detachment of colloidal particles from collector surfaces in a parallel plate flow chamber and generally polystyrene particles with a diameter of 806 nm detached less than particles with a diameter of 1400 nm. Particle

  10. Fermionic Casimir effect for parallel plates in the presence of compact dimensions with applications to nanotubes

    International Nuclear Information System (INIS)

    Bellucci, S.; Saharian, A. A.

    2009-01-01

    We evaluate the Casimir energy and force for a massive fermionic field in the geometry of two parallel plates on background of Minkowski spacetime with an arbitrary number of toroidally compactified spatial dimensions. The bag boundary conditions are imposed on the plates and periodicity conditions with arbitrary phases are considered along the compact dimensions. The Casimir energy is decomposed into purely topological, single plate and interaction parts. With independence of the lengths of the compact dimensions and the phases in the periodicity conditions, the interaction part of the Casimir energy is always negative. In order to obtain the resulting force, the contributions from both sides of the plates must be taken into account. Then, the forces coming from the topological parts of the vacuum energy cancel out and only the interaction term contributes to the Casimir force. Applications of the general formulae to Kaluza-Klein-type models and carbon nanotubes are given. In particular, we show that for finite-length metallic nanotubes, the Casimir forces acting on the tube edges are always attractive, whereas for semiconducting-type ones, they are attractive for small lengths of the nanotube and repulsive for large lengths.

  11. Development of a parallel plate ion chamber for radiation protection level

    International Nuclear Information System (INIS)

    Bottaro, Marcio; Landi, Mauricio; Moralles, Mauricio

    2011-01-01

    A new parallel plate vented ion chamber is proposed in this paper. The application of this chamber was primarily intended to the measurement of stray radiation in interventional procedures, but the energy response of about 2.6%, which was obtained in the first prototype, on the range from 40 to 150 kV using ISO 4037-1 narrow qualities, provided the possibility of a wide modality application on radiation protection. Primary studies with Maxwell 2D electromagnetic field simulator revealed an optimized model regarding effective volume and saturation voltage levels, which conferred to the ion chamber a dual entrance window feature. The development of this ion chamber has the main contribution of Monte Carlo calculations as a support tool to the establishment of the effective volume of the chamber and determination of the best materials for housing mounting and conductive elements, such as guard rings, electrode, and windows. Even the composition of the conductive layers, which would be neglected due to their very small thicknesses (about 35 μm), had important influence on the results and could be better understood with Monte Carlo N-Particle Transport Code System (MCNP) simulations. (author)

  12. Oscillatory flow at the end of parallel-plate stacks: phenomenological and similarity analysis

    International Nuclear Information System (INIS)

    Mao Xiaoan; Jaworski, Artur J

    2010-01-01

    This paper addresses the physics of the oscillatory flow in the vicinity of a series of parallel plates forming geometrically identical channels. This type of flow is particularly relevant to thermoacoustic engines and refrigerators, where a reciprocating flow is responsible for the desirable energy transfer, but it is also of interest to general fluid mechanics of oscillatory flows past bluff bodies. In this paper, the physics of an acoustically induced flow past a series of plates in an isothermal condition is studied in detail using the data provided by PIV imaging. Particular attention is given to the analysis of the wake flow during the ejection part of the flow cycle, where either closed recirculating vortices or alternating vortex shedding can be observed. This is followed by a similarity analysis of the governing Navier-Stokes equations in order to derive the similarity criteria governing the wake flow behaviour. To this end, similarity numbers including two types of Reynolds number, the Keulegan-Carpenter number and a non-dimensional stack configuration parameter, d/h, are considered and their influence on the phenomena are discussed.

  13. Project, construction and calibration of parallel plate ionization chambers for x-radiation

    International Nuclear Information System (INIS)

    Albuquerque, M.P.P.

    1989-01-01

    Two pairs of parallel-plate ionization chambers were projected and constructed. In each pair one of the chambers has a collecting electrode and a guard ring made of graphite and the other, of aluminium. The difference between both pairs is that in only one case screws were used to fix the chamber components. The chambers are made of Lucite with aluminized Mylar entrance windows; they have circular form and are unsealed. All chamber components are easily available. The main chamber characteristics were determined, applying the tests of current leakage, repetitively and long term stability. The energy and angular dependence, and the polarity effect were also studied, obtaining the saturation curves and determining the build-up effect for gamma radiation detection. The chambers were calibrated with low and intermediate energy X-radiation, gamma radiation of sup(60)Co an sup(137)Cs, and beta radiation of sup(90)Sr + sup(90)Y. The obtained results show the viability of utilization of these chambers in radiation dosimetry and the results were compared with those of imported commercial ionization chambers of the secondary standard type. The great difference between the energy dependence of the chambers according to the collecting electrode material, allowed the formation of a Tandem system (constituted by a chamber pair A, C), for the determination of the effective energy and the exposure rate in air of unknown X-radiation fields, in the case of low intermediate energy ranges. (author)

  14. Slit shaped microwave induced atmospheric pressure plasma based on a parallel plate transmission line resonator

    Science.gov (United States)

    Kang, S. K.; Seo, Y. S.; Lee, H. Wk; Aman-ur-Rehman; Kim, G. C.; Lee, J. K.

    2011-11-01

    A new type of microwave-excited atmospheric pressure plasma source, based on the principle of parallel plate transmission line resonator, is developed for the treatment of large areas in biomedical applications such as skin treatment and wound healing. A stable plasma of 20 mm width is sustained by a small microwave power source operated at a frequency of 700 MHz and a gas flow rate of 0.9 slm. Plasma impedance and plasma density of this plasma source are estimated by fitting the calculated reflection coefficient to the measured one. The estimated plasma impedance shows a decreasing trend while estimated plasma density shows an increasing trend with the increase in the input power. Plasma uniformity is confirmed by temperature and optical emission distribution measurements. Plasma temperature is sustained at less than 40 °C and abundant amounts of reactive species, which are important agents for bacteria inactivation, are detected over the entire plasma region. Large area treatment ability of this newly developed device is verified through bacteria inactivation experiment using E. coli. Sterilization experiment shows a large bacterial killing mark of 25 mm for a plasma treatment time of 10 s.

  15. Mass-transfer characterization in a parallel-plate electrochemical reactor with convergent flow

    International Nuclear Information System (INIS)

    Colli, A.N.; Bisang, J.M.

    2013-01-01

    Highlights: • A convergent laminar flow enhances and becomes more uniform the mass-transfer rate. • The mass-transfer rate is increased under convergent turbulent flow conditions. • The mass-transfer rate under convergent laminar flow can be theoretically predicted. • A convergent duct improves the reactor behaviour and the concept is easily applicable. -- Abstract: A continuous reduction in the cross-section area is analysed as a means of improving mass-transfer in a parallel-plate electrochemical reactor. Experimental local mass-transfer coefficients along the electrode length are reported for different values of the convergent ratio and Reynolds numbers, using the reduction of ferricyanide as a test reaction. The Reynolds numbers evaluated at the reactor inlet range from 85 to 4600 with interelectrode gaps of 2 and 4 mm. The convergent flow improves the mean mass-transfer coefficient by 10–60% and mass-transfer distribution under laminar flow conditions becomes more uniform. The experimental data under laminar flow conditions are compared with theoretical calculations obtained by a computational fluid dynamics software and also with an analytical simplified model. A suitable agreement is observed between both theoretical treatments and with the experimental results. The pressure drop across the reactor is reported and compared with theoretical predictions

  16. Transmission Characteristics of a Generalized Parallel Plate Dielectric Waveguide at THz Frequencies

    International Nuclear Information System (INIS)

    Ye Long-Fang; Xu Rui-Min; Zhang Yong; Lin Wei-Gan

    2011-01-01

    A generalized parallel-plate dielectric waveguide (G-PPDW) is proposed as a new guiding medium for terahertz wave. A theoretical analysis of the transmission characteristics for the TE modes of this generalized structure is performed. Equations are presented for the field components, dispersion, power ratio, transmission loss and characteristic impedance as functions of the operating frequencies, dimensions and material constants. In the case of the lowest-order mode TE 10 , design curves covering frequencies and dimensions for the given material constants in the THz region are presented. The theoretical results of transmission characteristics obtained from these equations are verified by the finite-element method with a good agreement. The investigation results show that by selecting proper dimensions and dielectric materials, G-PPDW can be used to guide THz waves efficiently with high power confinement and low attenuation. These outstanding properties may open up a way to many important applications for THz integrated circuits and systems. (fundamental areas of phenomenology(including applications))

  17. Compounded natural convection enhancement in a vertical parallel-plate channel

    Energy Technology Data Exchange (ETDEWEB)

    Andreozzi, Assunta [Dipartimento di Energetica, Termofluidodinamica Applicata e Condizionamenti Ambientali, Universita degli Studi di Napoli Federico II, Piazzale Tecchio 80, 80125 Napoli (Italy); Campo, Antonio [Department of Mechanical Engineering, The University of Vermont, 33 Colchester Ave., Burlington, VT 05405 (United States); Manca, Oronzio [Dipartimento di Ingegneria Aerospaziale e Meccanica, Seconda Universita degli Studi di Napoli, via Roma 29, Aversa (CE) 81031 (Italy)

    2008-06-15

    This paper addresses the natural convection behavior of air when heated in single vertical, parallel-plate channels. To enhance the heat transfer two passive schemes are combined: (1) an equidistant short plate is inserted at the inlet and (2) two parallel, colinear insulated plates are appended at the exit. The channel plates are symmetrically heated with a uniform heat flux. The computational procedure is made by solving the full elliptic Navier-Stokes and energy equations with the finite-volume methodology in an I-type computational domain that is much larger than the physical domain. Within the framework of a ''proof-of-concept'' the controlling Grashof number based on the heated plate height ranges between 10{sup 3} and 10{sup 6}. The numerical velocity, pressure and temperature fields are post-processed to compute the quantities of engineering interest such as the induced mass flow rate, the pressure at the channel mid-plane and the temperature along the plates. In addition, the Nusselt number and the average Nusselt number, both based on the heated plate height, are presented in graphical form. At the end, optimal channel configurations expressed in terms of the highest average Nusselt number are obtained for the pair of pre-assigned Grashof numbers. (author)

  18. Synchronized Molecular-Dynamics simulation for thermal lubrication of a polymeric liquid between parallel plates

    Science.gov (United States)

    Yasuda, Shugo; Yamamoto, Ryoichi

    2015-11-01

    The Synchronized Molecular-Dynamics simulation which was recently proposed by authors is applied to the analysis of polymer lubrication between parallel plates. In the SMD method, the MD simulations are assigned to small fluid elements to calculate the local stresses and temperatures and are synchronized at certain time intervals to satisfy the macroscopic heat- and momentum-transport equations.The rheological properties and conformation of the polymer chains coupled with local viscous heating are investigated with a non-dimensional parameter, the Nahme-Griffith number, which is defined as the ratio of the viscous heating to the thermal conduction at the characteristic temperature required to sufficiently change the viscosity. The present simulation demonstrates that strong shear thinning and a transitional behavior of the conformation of the polymer chains are exhibited with a rapid temperature rise when the Nahme-Griffith number exceeds unity.The results also clarify that the reentrant transition of the linear stress-optical relation occurs for large shear stresses due to the coupling of the conformation of polymer chains with heat generation under shear flows. This study was financially supported by JSPS KAKENHI Grant Nos. 26790080 and 26247069.

  19. Novel parallel plate condenser for single particle electrostatic force measurements in atomic force microscope

    KAUST Repository

    Kwek, Jin Wang

    2011-07-01

    A combination of small parallel plate condenser with Indium Tin Oxide (ITO) glass slides as electrodes and an atomic force microscope (AFM) is used to characterize the electrostatic behavior of single glass bead microparticles (105-150 μm) glued to the AFM cantilever. This novel setup allows measurements of the electrostatic forces acting on a particle in an applied electrical field to be performed in ambient air conditions. By varying the position of the microparticle between the electrodes and the strength of the applied electric field, the relative contributions of the particle net charge, induced and image charges were investigated. When the microparticle is positioned in the middle of the electrodes, the force acting on the microparticle was linear with the applied electric field and proportional to the microparticle net charge. At distances close to the bottom electrode, the force follows a parabolic relationship with the applied electric field reflecting the contributions of induced and image charges. The method can be used for the rapid evaluation of the charging and polarizability properties of the microparticle as well as an alternative to the conventional Faraday\\'s pail technique. © 2011 Elsevier B.V.

  20. The application of structural nonlinearity in the development of linearly tunable MEMS capacitors

    International Nuclear Information System (INIS)

    Shavezipur, M; Khajepour, A; Hashemi, S M

    2008-01-01

    Electrostatically actuated parallel-plate tunable capacitors are the most desired MEMS capacitors because of their smaller sizes and higher Q-factors. However, these capacitors suffer from low tunability and exhibit high sensitivity near the pull-in voltage which counters the concept of tunability. In this paper, a novel design for parallel-plate tunable capacitors with high tunability and linear capacitance–voltage (C–V) response is developed. The design uses nonlinear structural rigidities to relieve intrinsic electrostatic nonlinearity in MEMS capacitors. Based on the force–displacement characteristic of an ideally linear capacitor, a real beam-like nonlinear spring model is developed. The variable stiffness coefficients of such springs improve the linearity of the C–V curve. Moreover, because the structural stiffness increases with deformations, the pull-in is delayed and higher tunability is achieved. Finite element simulations reveal that capacitors with air gaps larger than 4 µm and supporting beams thinner than 1 µm can generate highly linear C–V responses and tunabilities over 120%. Experimental results for capacitors fabricated by PolyMUMPs verify the effect of weak nonlinear geometric stiffness on improving the tunability for designs with a small air gap and relatively thick structural layers

  1. Irreversible Electroporation of the Pancreas Using Parallel Plate Electrodes in a Porcine Model: A Feasibility Study.

    Science.gov (United States)

    Rombouts, Steffi J E; Nijkamp, Maarten W; van Dijck, Willemijn P M; Brosens, Lodewijk A A; Konings, Maurits; van Hillegersberg, R; Borel Rinkes, Inne H M; Hagendoorn, Jeroen; Wittkampf, Fred H; Molenaar, I Quintus

    2017-01-01

    Irreversible electroporation (IRE) with needle electrodes is being explored as treatment option in locally advanced pancreatic cancer. Several studies have shown promising results with IRE needles, positioned around the tumor to achieve tumor ablation. Disadvantages are the technical difficulties for needle placement, the time needed to achieve tumor ablation, the risk of needle track seeding and most important the possible occurrence of postoperative pancreatic fistula via the needle tracks. The aim of this experimental study was to evaluate the feasibility of a new IRE-technique using two parallel plate electrodes, in a porcine model. Twelve healthy pigs underwent laparotomy. The pancreas was mobilized to enable positioning of the paddles. A standard monophasic external cardiac defibrillator was used to perform an ablation in 3 separate parts of the pancreas; either a single application of 50 or 100J or a serial application of 4x50J. After 6 hours, pancreatectomy was performed for histology and pigs were terminated. Histology showed necrosis of pancreatic parenchyma with neutrophil influx in 5/12, 11/12 and 12/12 of the ablated areas at 50, 100, and 4x50J respectively. The electric current density threshold to achieve necrosis was 4.3, 5.1 and 3.4 A/cm2 respectively. The ablation threshold was significantly lower for the serial compared to the single applications (p = 0.003). The content of the ablated areas differed between the applications: areas treated with a single application of 50 J often contained vital areas without obvious necrosis, whereas half of the sections treated with 100 J showed small islands of normal looking cells surrounded by necrosis, while all sections receiving 4x 50 J showed a homogeneous necrotic lesion. Pancreatic tissue can be successfully ablated using two parallel paddles around the tissue. A serial application of 4x50J was most effective in creating a homogeneous necrotic lesion.

  2. Irreversible Electroporation of the Pancreas Using Parallel Plate Electrodes in a Porcine Model: A Feasibility Study.

    Directory of Open Access Journals (Sweden)

    Steffi J E Rombouts

    Full Text Available Irreversible electroporation (IRE with needle electrodes is being explored as treatment option in locally advanced pancreatic cancer. Several studies have shown promising results with IRE needles, positioned around the tumor to achieve tumor ablation. Disadvantages are the technical difficulties for needle placement, the time needed to achieve tumor ablation, the risk of needle track seeding and most important the possible occurrence of postoperative pancreatic fistula via the needle tracks. The aim of this experimental study was to evaluate the feasibility of a new IRE-technique using two parallel plate electrodes, in a porcine model.Twelve healthy pigs underwent laparotomy. The pancreas was mobilized to enable positioning of the paddles. A standard monophasic external cardiac defibrillator was used to perform an ablation in 3 separate parts of the pancreas; either a single application of 50 or 100J or a serial application of 4x50J. After 6 hours, pancreatectomy was performed for histology and pigs were terminated.Histology showed necrosis of pancreatic parenchyma with neutrophil influx in 5/12, 11/12 and 12/12 of the ablated areas at 50, 100, and 4x50J respectively. The electric current density threshold to achieve necrosis was 4.3, 5.1 and 3.4 A/cm2 respectively. The ablation threshold was significantly lower for the serial compared to the single applications (p = 0.003. The content of the ablated areas differed between the applications: areas treated with a single application of 50 J often contained vital areas without obvious necrosis, whereas half of the sections treated with 100 J showed small islands of normal looking cells surrounded by necrosis, while all sections receiving 4x 50 J showed a homogeneous necrotic lesion.Pancreatic tissue can be successfully ablated using two parallel paddles around the tissue. A serial application of 4x50J was most effective in creating a homogeneous necrotic lesion.

  3. Electrochemical oxidation of phenol in a parallel plate reactor using ruthenium mixed metal oxide electrode

    Energy Technology Data Exchange (ETDEWEB)

    Yavuz, Yusuf [Anadolu Universitesi, Cevre Sor. Uyg. ve Aras. Merkezi, Eskisehir (Turkey); Koparal, A. Savas [Anadolu Universitesi, Cevre Sor. Uyg. ve Aras. Merkezi, Eskisehir (Turkey)]. E-mail: askopara@anadolu.edu.tr

    2006-08-21

    In this study, electrochemical oxidation of phenol was carried out in a parallel plate reactor using ruthenium mixed metal oxide electrode. The effects of initial pH, temperature, supporting electrolyte concentration, current density, flow rate and initial phenol concentration on the removal efficiency were investigated. Model wastewater prepared with distilled water and phenol, was recirculated to the electrochemical reactor by a peristaltic pump. Sodium sulfate was used as supporting electrolyte. The Microtox'' (registered) bioassay was also used to measure the toxicity of the model wastewater during the study. As a result of the study, removal efficiency of 99.7% and 88.9% were achieved for the initial phenol concentration of 200 mg/L and chemical oxygen demand (COD) of 480 mg/L, respectively. In the same study, specific energy consumption of 1.88 kWh/g phenol removed and, mass transfer coefficient of 8.62 x 10{sup -6} m/s were reached at the current density of 15 mA/cm{sup 2}. Electrochemical oxygen demand (EOD), which can be defined as the amount of electrochemically formed oxygen used for the oxidation of organic pollutants, was 2.13 g O{sub 2}/g phenol. Electrochemical oxidation of petroleum refinery wastewater was also studied at the optimum experimental conditions obtained. Phenol removal of 94.5% and COD removal of 70.1% were reached at the current density of 20 mA/cm{sup 2} for the petroleum refinery wastewater.

  4. Vented Capacitor

    Science.gov (United States)

    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.

  5. Observation of Cherenkov rings using a low-pressure parallel-plate chamber and a solid cesium-iodide photocathode

    International Nuclear Information System (INIS)

    Lockyer, N.S.; Millan, J.E.; Lu, C.; McDonald, K.T.; Lopez, A.

    1993-01-01

    We have observed Cherenkov rings from minimum-ionizing particles using a low-pressure, parallel-plate pad-chamber with a cesium-iodide solid photocathode. This detector is blind to minimum-ionizing particles, and sensitive to Cherenkov photons of wavelengths 170-210 nm. An average of 5 photoelectrons per Cherenkov ring were detected using a 2-cm-thick radiator of liquid C 6 F 14 . This paper reports on the chamber construction, photocathode preparation and testbeam results. (orig.)

  6. Hall effects on unsteady MHD reactive flow of second grade fluid through porous medium in a rotating parallel plate channel

    Science.gov (United States)

    Krishna, M. Veera; Swarnalathamma, B. V.

    2017-07-01

    We considered the transient MHD flow of a reactive second grade fluid through porous medium between two infinitely long horizontal parallel plates when one of the plate is set into uniform accelerated motion in the presence of a uniform transverse magnetic field under Arrhenius reaction rate. The governing equations are solved by Laplace transform technique. The effects of the pertinent parameters on the velocity, temperature are discussed in detail. The shear stress and Nusselt number at the plates are also obtained analytically and computationally discussed with reference to governing parameters.

  7. Comparison of Different Analytic Solutions to Axisymmetric Squeezing Fluid Flow between Two Infinite Parallel Plates with Slip Boundary Conditions

    Directory of Open Access Journals (Sweden)

    Hamid Khan

    2012-01-01

    Full Text Available We investigate squeezing flow between two large parallel plates by transforming the basic governing equations of the first grade fluid to an ordinary nonlinear differential equation using the stream functions ur(r,z,t=(1/r(∂ψ/∂z and uz(r,z,t=−(1/r(∂ψ/∂r and a transformation ψ(r,z=r2F(z. The velocity profiles are investigated through various analytical techniques like Adomian decomposition method, new iterative method, homotopy perturbation, optimal homotopy asymptotic method, and differential transform method.

  8. Guidelines for Selection, Screening and Qualification of Low-Voltage Commercial Multilayer Ceramic Capacitors for Space Programs

    Science.gov (United States)

    Teverovsky, Alexander A.

    2012-01-01

    This document has been developed in the course of NASA Electronic Parts and Packaging (NEPP) program and is not an official endorsement of the insertion of commercial capacitors in space programs or an established set of requirements for their testing. The purpose of this document is to suggest possible ways for selection, screening, and qualification of commercial capacitors for NASA projects and open discussions in the parts engineering community related to the use of COTS ceramic capacitors. This guideline is applicable to commercial surface mount chip, simple parallel plate design, multi-layer ceramic capacitors (MLCCs) rated to voltages of 100V and less. Parts with different design, e.g. low inductance ceramic capacitors (LICA), land grid array (LGA) etc., might need additional testing and tailoring of the requirements described in this document. Although the focus of this document is on commercial MLCCs, many procedures discussed below would be beneficial for military-grade capacitors

  9. Removal of antibiotics in a parallel-plate thin-film-photocatalytic reactor: Process modeling and evolution of transformation by-products and toxicity.

    Science.gov (United States)

    Özkal, Can Burak; Frontistis, Zacharias; Antonopoulou, Maria; Konstantinou, Ioannis; Mantzavinos, Dionissios; Meriç, Süreyya

    2017-10-01

    Photocatalytic degradation of sulfamethoxazole (SMX) antibiotic has been studied under recycling batch and homogeneous flow conditions in a thin-film coated immobilized system namely parallel-plate (PPL) reactor. Experimentally designed, statistically evaluated with a factorial design (FD) approach with intent to provide a mathematical model takes into account the parameters influencing process performance. Initial antibiotic concentration, UV energy level, irradiated surface area, water matrix (ultrapure and secondary treated wastewater) and time, were defined as model parameters. A full of 2 5 experimental design was consisted of 32 random experiments. PPL reactor test experiments were carried out in order to set boundary levels for hydraulic, volumetric and defined defined process parameters. TTIP based thin-film with polyethylene glycol+TiO 2 additives were fabricated according to pre-described methodology. Antibiotic degradation was monitored by High Performance Liquid Chromatography analysis while the degradation products were specified by LC-TOF-MS analysis. Acute toxicity of untreated and treated SMX solutions was tested by standard Daphnia magna method. Based on the obtained mathematical model, the response of the immobilized PC system is described with a polynomial equation. The statistically significant positive effects are initial SMX concentration, process time and the combined effect of both, while combined effect of water matrix and irradiated surface area displays an adverse effect on the rate of antibiotic degradation by photocatalytic oxidation. Process efficiency and the validity of the acquired mathematical model was also verified for levofloxacin and cefaclor antibiotics. Immobilized PC degradation in PPL reactor configuration was found capable of providing reduced effluent toxicity by simultaneous degradation of SMX parent compound and TBPs. Copyright © 2017. Published by Elsevier B.V.

  10. Electrochemical capacitor

    Science.gov (United States)

    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.

  11. Switchable capacitor

    NARCIS (Netherlands)

    Rottenberg, Xavier; Jansen, Henricus V.; Tilmans, H.A.C.; Tilmans, Hendrikus; De Raedt, Walter

    2011-01-01

    A micro electromechanical switchable capacitor is disclosed, comprising a substrate, a bottom elecrode, a dielaectric layer deposited on at least part of sai bottum electrode, a conductive floating electrode deposited on at least part of said dielectric layer, an armature positioned proximate to the

  12. Switchable capacitor

    NARCIS (Netherlands)

    Rottenberg, X.; Jansen, Henricus V.; Tilmans, H.A.C.; De Raedt, W.

    2003-01-01

    A micro electromechanical switchable capacitor is disclosed, comprising a substrate, a bottom elecrode, a dielaectric layer deposited on at least part of sai bottum electrode, a conductive floating electrode deposited on at least part of said dielectric layer, an armature positioned proximate to the

  13. Rotary capacitor

    CERN Multimedia

    CERN PhotoLab

    1971-01-01

    The rotating wheel of the rotary capacitor representing the most critical part of the new radio-frequency system of the synchro-cyclotron. The three rows of teeth on the circumference of the wheel pass between four rows of stator blades with a minimum clearance of 1 mm at a velocity of 1700 rev/min.

  14. Multiple Interfacial Fe3O4@BaTiO3/P(VDF-HFP) Core-Shell-Matrix Films with Internal Barrier Layer Capacitor (IBLC) Effects and High Energy Storage Density.

    Science.gov (United States)

    Zhou, Ling; Fu, Qiuyun; Xue, Fei; Tang, Xiahui; Zhou, Dongxiang; Tian, Yahui; Wang, Geng; Wang, Chaohong; Gou, Haibo; Xu, Lei

    2017-11-22

    Flexible nanocomposites composed of high dielectric constant fillers and polymer matrix have shown great potential for electrostatic capacitors and energy storage applications. To obtain the composited material with high dielectric constant and high breakdown strength, multi-interfacial composited particles, which composed of conductive cores and insulating shells and possessed the internal barrier layer capacitor (IBLC) effect, were adopted as fillers. Thus, Fe 3 O 4 @BaTiO 3 core-shell particles were prepared and loaded into the poly(vinylidene fluoride-co-hexafluoropropylene) (P(VDF-HFP)) polymer matrix. As the mass fraction of core-shell fillers increased from 2.5 wt % to 30 wt %, the dielectric constant of the films increased, while the loss tangent remained at a low level (capacitor model was also adopted to interpret the efficiency of IBLC effects on the suppressed loss tangent and the superior breakdown strength. This work explored an effective approach to prepare dielectric nanocomposites for energy storage applications experimentally and theoretically.

  15. Evaluation of the hydrodynamic behaviour of turbulence promoters in parallel plate electrochemical reactors by means of the dispersion model

    International Nuclear Information System (INIS)

    Colli, A.N.; Bisang, J.M.

    2011-01-01

    Highlights: · The type of turbulence promoters has a strong influence on the hydrodynamics. · The dispersion model is appropriate for expanded plastic turbulence promoters. · The dispersion model is appropriate for glass beads turbulence promoters. - Abstract: The hydrodynamic behaviour of electrochemical reactors with parallel plate electrodes is experimentally studied using the stimulus-response method either with an empty reactor or with different turbulence promoters. Theoretical results which are in accordance with the analytical and numerical resolution of the dispersion model for a closed system are compared with the classical relationships of the normalized outlet concentration for open systems and the validity range of the equations is discussed. The experimental results were well correlated with the dispersion model using glass beads or expanded plastic meshes as turbulence promoters, which have shown the most advantageous performance. The Peclet number was higher than 63. The dispersion coefficient was found to increase linearly with flow velocity in these cases.

  16. Heat transfer and flow analysis of nanofluid flow between parallel plates in presence of variable magnetic field using HPM

    Energy Technology Data Exchange (ETDEWEB)

    Hatami, M., E-mail: m.hatami@tue.nl [Esfarayen University of Technology, Mechanical Engineering Department, Esfarayen, North Khorasan (Iran, Islamic Republic of); Jing, Dengwei; Song, Dongxing [International Research Center for Renewable Energy, State Key Laboratory of Multiphase Flow in Power Engineering, Xi’an Jiaotong University, Xi' an 710049 (China); Sheikholeslami, M.; Ganji, D.D. [Department of Mechanical Engineering, Babol University of Technology, Babol (Iran, Islamic Republic of)

    2015-12-15

    In this study, effect of variable magnetic field on nanofluid flow and heat transfer analysis between two parallel disks is investigated. By using the appropriate transformation for the velocity, temperature and concentration, the basic equations governing the flow, heat and mass transfer were reduced to a set of ordinary differential equations. These equations subjected to the associated boundary conditions were solved analytically using Homotopy perturbation method. The analytical investigation is carried out for different governing parameters namely: squeeze number, suction parameter, Hartmann number, Brownian motion parameter, thermophrotic parameter and Lewis number. Results show that Nusselt number has direct relationship with Brownian motion parameter and thermophrotic parameter but it is a decreasing function of squeeze number, suction parameter, Hartmann number and Lewis number. - Highlights: • Heat and mass transfer of nanofluids between parallel plates investigated. • A variable magnetic field is applied on the plates. • Governing equations are solved analytically. • Effects of physical parameters are discussed on the Nusselt number.

  17. Homogeneous and Stratified Liquid-Liquid Flow Effect of a Viscosity Reducer: I. Comparison in parallel plates for heavy crude

    Directory of Open Access Journals (Sweden)

    E. J. Suarez-Dominguez

    2016-12-01

    Full Text Available Production of heavy crude oil in Mexico, and worldwide, is increasing which has led to the application of different methods to reduce viscosity or to enhance transport through stratified flow to continue using the existing infrastructures. In this context, injecting a viscosity improver that does not mix completely with the crude, establishes a liquid-liquid stratified flow. On the basis of a parallel plates model, comparing the increase of flow that occurs in the one-phase case which assumes a complete mixture between the crude and the viscosity improver against another stratified liquid-liquid (no mixing between the oil and compared improver; it was found that in both cases there is a flow increase for the same pressure drop with a maximum for the case in which the flow improver is between the plates and the crude.

  18. Study and realization of a parallel plate avalanche counter used for time of flight and localization measurements

    International Nuclear Information System (INIS)

    Pellegrin, P.O.

    1985-01-01

    A parallel Plates Avalanche Counter (P.P.A.C.) allowing high resolution training and localization is studied. It is designed to be placed on the beam trajectory-including the magnetic spectrometer of SARA accelerator at ISN Grenoble. Two purposes are searched: firstly to improve the time-of-flight measurement due to the very high intrinsic time resolution (it can be less than 150 ps), secondly to measure with accuracy the scattering angle of the particle on the target, due to its localization. The detector thickness has been reduced to set aside as unimportant the disturbance produced on the particle trajectory. The theoretical aspect of the detector operation and a quantitative study of the disturbances it causes on particle energy are presented. The set-up and its necessary surroundings are described with experimental results of its characteristics [fr

  19. Evaluation of RANS and LES models for Natural Convection in High-Aspect-Ratio Parallel Plate Channels

    Science.gov (United States)

    Fradeneck, Austen; Kimber, Mark

    2017-11-01

    The present study evaluates the effectiveness of current RANS and LES models in simulating natural convection in high-aspect ratio parallel plate channels. The geometry under consideration is based on a simplification of the coolant and bypass channels in the very high-temperature gas reactor (VHTR). Two thermal conditions are considered, asymmetric and symmetric wall heating with an applied heat flux to match Rayleigh numbers experienced in the VHTR during a loss of flow accident (LOFA). RANS models are compared to analogous high-fidelity LES simulations. Preliminary results demonstrate the efficacy of the low-Reynolds number k- ɛ formulations and their enhancement to the standard form and Reynolds stress transport model in terms of calculating the turbulence production due to buoyancy and overall mean flow variables.

  20. Heat transfer and flow analysis of nanofluid flow between parallel plates in presence of variable magnetic field using HPM

    International Nuclear Information System (INIS)

    Hatami, M.; Jing, Dengwei; Song, Dongxing; Sheikholeslami, M.; Ganji, D.D.

    2015-01-01

    In this study, effect of variable magnetic field on nanofluid flow and heat transfer analysis between two parallel disks is investigated. By using the appropriate transformation for the velocity, temperature and concentration, the basic equations governing the flow, heat and mass transfer were reduced to a set of ordinary differential equations. These equations subjected to the associated boundary conditions were solved analytically using Homotopy perturbation method. The analytical investigation is carried out for different governing parameters namely: squeeze number, suction parameter, Hartmann number, Brownian motion parameter, thermophrotic parameter and Lewis number. Results show that Nusselt number has direct relationship with Brownian motion parameter and thermophrotic parameter but it is a decreasing function of squeeze number, suction parameter, Hartmann number and Lewis number. - Highlights: • Heat and mass transfer of nanofluids between parallel plates investigated. • A variable magnetic field is applied on the plates. • Governing equations are solved analytically. • Effects of physical parameters are discussed on the Nusselt number

  1. Heat and Mass Transfer on Squeezing Unsteady MHD Nano fluid Flow between Parallel Plates with Slip Velocity Effect

    International Nuclear Information System (INIS)

    Singh, K.; Rawat, S. K.; Kumar, M.

    2016-01-01

    Heat and mass transfer behavior of unsteady flow of squeezing between two parallel plates in the sight of uniform magnetic field with slip velocity effect is investigated. The governing equations representing fluid flow have been transformed into nonlinear ordinary differential equations using similarity transformation. The equations thus obtained have been solved numerically using Runge-Kutta-Fehlberg method with shooting technique. Effects on the behavior of velocity, temperature, and concentration for various values of relevant parameters are illustrated graphically. The skin-friction coefficient and heat and mass transfer rate are also tabulated for various governing parameters. The results indicate that, for nano fluid flow, the rates of heat and mass transfer are inversely proportional to nanoparticle volume fraction and magnetic parameter. The rate of mass transfer increases with increasing values of Schmidt number and squeeze number.

  2. A solution for the Graetz problem in parallel plates, with axial heat conduction in the fluid and in the wall

    International Nuclear Information System (INIS)

    Biage, M.

    1983-04-01

    A heat transfer problem in parallel plates with infinite with has been solved, with axial heat conduction in the fluid and in the wall, considering steady-state laminar flow for a Newtonian fluid and a fully developed velocity profile. The duct consists of an infinite inicial part, insulated on both plates, an intermediale part of finite length, with a prescribed heat flux in the upper plate and insulated on the botton plate, and by another infinite part also insulated on both plates. The problem has been solved by a numerical combination of the integral equation method and the variational method. Both, the performance of the numerical technique employed and results obtained are analyzed in this work. It is demostrated that the heat conduction in the wall significantly modifies the heat transfer parameters. (Author) [pt

  3. Predictions of the effect of stratification on superimposed forced and free convection between vertical parallel plates for various boundary conditions

    International Nuclear Information System (INIS)

    Cowan, G.H.; Irvine, T.J. Jr.; Quarini, G.L.

    1983-01-01

    The velocity and temperature equations for laminar buoyancy and forced convection flows between vertical flat parallel plates are presented. The thermal boundary conditions on the plate define the buoyancy driven field, while the channel Reynolds number defines the forced flow field. Specific examples relating to tall narrow channels with laminar convention and to closed high ratio cavities (as may be found in the proposed active and passive insulation systems for sodium cooled fast reactors) are presented. The analysis is limited to the laminar flow regimes, whilst some reactor situations are likely to be turbulent, hence a proposal for a simple extension of this analysis to the turbulent regime is made. It is shown how the analysis can be made to apply to fluids of various Prandtl numbers. (author)

  4. Energy dependence of an ionization chamber with parallel plates in standard gamma and x-radiation fields

    International Nuclear Information System (INIS)

    Batistella, M.A.; Caldas, L.V.E.

    1988-09-01

    The characteristics of low energy X-radiation standard fields were determined and the energy dependence of a ionization chamber of the superficial type, with parallel plates and fixed volume, normally utilized in the dosimetry at the Radiotherapy level was studied. The possibility of adaptation of this chamber type for use in gamma radiation dosimetry was verified. Different thickness Lucite build-up caps, from 2.0 up to 5.5 mm, were produced and tested in 60 Co and 137 Cs gamma radiation fields. This type of detector, with the adequate build-up cap, presented a performance comparable to that of the thimble type ionization chamber. It was concluded that it is not necessary to use different kinds of chambers for each high and mean energy interval. The superficial chamber, specially produced to detect low energy X-radiation, may be adapted to detect gamma radiation. (author) [pt

  5. Capacitor-based detection of nuclear magnetization: nuclear quadrupole resonance of surfaces.

    Science.gov (United States)

    Gregorovič, Alan; Apih, Tomaž; Kvasić, Ivan; Lužnik, Janko; Pirnat, Janez; Trontelj, Zvonko; Strle, Drago; Muševič, Igor

    2011-03-01

    We demonstrate excitation and detection of nuclear magnetization in a nuclear quadrupole resonance (NQR) experiment with a parallel plate capacitor, where the sample is located between the two capacitor plates and not in a coil as usually. While the sensitivity of this capacitor-based detection is found lower compared to an optimal coil-based detection of the same amount of sample, it becomes comparable in the case of very thin samples and even advantageous in the proximity of conducting bodies. This capacitor-based setup may find its application in acquisition of NQR signals from the surface layers on conducting bodies or in a portable tightly integrated nuclear magnetic resonance sensor. Copyright © 2010 Elsevier Inc. All rights reserved.

  6. Experimental investigation of critical velocity in a parallel plate research reactor fuel assembly

    Energy Technology Data Exchange (ETDEWEB)

    Castro, Alfredo J.A.; Scuro, Nikolas L.; Andrade, Delvonei A., E-mail: ajcastro@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNE-SP), Sao Paulo, SP (Brazil)

    2017-07-01

    The fuel elements of a MTR (Material Testing Reactor) type nuclear reactor are mostly composed of aluminum coated fuel plates containing the core of uranium silica (U{sub 3}Si{sub 2}) dispersed in an aluminum matrix. These plates have a thickness of the order of millimeters and are much longer in relation to their thickness. They are arranged in parallel in the assembly of the fuel element to form channels between them a few millimeters in thickness, through which there is a flow of the coolant. This configuration, combined with the need for a flow at high flow rates to ensure the cooling of the fuel element in operation, may create problems of mechanical failure of fuel plate due to the vibration induced by the flow in the channels. In the case of critical velocity excessive permanent deflections of the plates can cause blockage of the flow channel in the reactor core and lead to overheating in the plates. For this study an experimental bench capable of high volume flows and a test section that simulates a plate-like fuel element with three cooling channels were developed. The dimensions of the test section were based on the dimensions of the Fuel Element of the Brazilian Multipurpose Reactor (RMB), whose project is being coordinated by the National Commission of Nuclear Energy (CNEN). The experiments performed attained the objective of reaching Miller's critical velocity condition. The critical velocity was reached with 14.5 m/s leading to the consequent plastic deformation of the flow channel plates. (author)

  7. Signal enhancement due to high-Z nanofilm electrodes in parallel plate ionization chambers with variable microgaps.

    Science.gov (United States)

    Brivio, Davide; Sajo, Erno; Zygmanski, Piotr

    2017-12-01

    We developed a method for measuring signal enhancement produced by high-Z nanofilm electrodes in parallel plate ionization chambers with variable thickness microgaps. We used a laboratory-made variable gap parallel plate ionization chamber with nanofilm electrodes made of aluminum-aluminum (Al-Al) and aluminum-tantalum (Al-Ta). The electrodes were evaporated on 1 mm thick glass substrates. The interelectrode air gap was varied from 3 μm to 1 cm. The gap size was measured using a digital micrometer and it was confirmed by capacitance measurements. The electric field in the chamber was kept between 0.1 kV/cm and 1 kV/cm for all the gap sizes by applying appropriate compensating voltages. The chamber was exposed to 120 kVp X-rays. The current was measured using a commercial data acquisition system with temporal resolution of 600 Hz. In addition, radiation transport simulations were carried out to characterize the dose, D(x), high-energy electron current, J(x), and deposited charge, Q(x), as a function of distance, x, from the electrodes. A deterministic method was selected over Monte Carlo due to its ability to produce results with 10 nm spatial resolution without stochastic uncertainties. Experimental signal enhancement ratio, SER(G) which we defined as the ratio of signal for Al-air-Ta to signal for Al-air-Al for each gap size, was compared to computations. The individual contributions of dose, electron current, and charge deposition to the signal enhancement were determined. Experimental signals matched computed data for all gap sizes after accounting for several contributions to the signal: (a) charge carrier generated via ionization due to the energy deposited in the air gap, D(x); (b) high-energy electron current, J(x), leaking from high-Z electrode (Ta) toward low-Z electrode (Al); (c) deposited charge in the air gap, Q(x); and (d) the decreased collection efficiency for large gaps (>~500 μm). Q(x) accounts for the electrons below 100 eV, which are

  8. Experimental investigation of thermal limits in parallel plate configuration for the future material testing reactor (JHR)

    International Nuclear Information System (INIS)

    Brigitte Noel

    2005-01-01

    Full text of publication follows: The design of the future material testing reactor, named Jules Horowitz Reactor and dedicated to technological irradiations, will allow very high performances. The JHR will be cooled and moderated by light water. The preliminary core of JHR consists of 46 assemblies, arranged in a triangular lattice inside a rectangular aluminium matrix. It is boarded on two sides by a beryllium reflector. The other two sides are left free in order to introduce mobile irradiation devices. The JHR assembly would be composed of 3 x 6 cylindrical fuel plates maintained by 3 stiffeners. The external diameter of the assembly is close to 8 cm with a 600 mm heated length, coolant channels having a 1.8 mm gap width. The JHR core must be designed to accommodate high power densities using a high coolant mass flux and sub-cooling level at moderate pressure. The JHR core configuration with multi-channels is subject to a potential excursive instability, called flow redistribution, and is distinguished from a true critical heat flux which would occur at a fixed channel flow rate. At thermal-hydraulic conditions applicable to the JHR, the availability of experimental data for both flow redistribution and CHF is very limited. Consequently, a thermal-hydraulic test facility (SULTAN-RJH) was designed and built in CEA-Grenoble to simulate a full-length coolant sub-channel representative of the JHR core, allowing determination of both thermal limits under relevant thermal hydraulics conditions. The SULTAN-RJH test section simulates a single sub-channel in the JHR core with a cross section corresponding to a mean span (∼50 mm) that has a full reactor length (600 mm), the same flow channel gap (1.5 mm) and Inconel plates of 1 mm thickness. The tests with light water flowing vertically upward will investigate a heat flux range of 0-7 MW/m 2 , velocity range of 0.6-18 m/s, exit pressure range of 0.2-1.0 MPa and inlet temperature range of 25-180 deg. C. The test section

  9. A comparative study of the effects of cone-plate and parallel-plate geometries on rheological properties under oscillatory shear flow

    CSIR Research Space (South Africa)

    Yong Song, H

    2017-11-01

    Full Text Available -1 Korea-Australia Rheology Journal A comparative study of the effects of cone-plate and parallel- plate geometries on rheological properties under oscillatory shear flow Hyeong Yong Song1, Reza Salehiyan2, Xiaolei Li1, Seung Hak Lee1 and Kyu Hyun1...

  10. Detachment of colloidal particles from collector surfaces with different electrostatic charge and hydrophobicity by attachment to air bubbles in a parallel plate flow chamber

    NARCIS (Netherlands)

    Suarez, CG; van der Mei, HC; Busscher, HJ

    1999-01-01

    The detachment of polystyrene particles adhering to collector surfaces with different electrostatic charge and hydrophobicity by attachment to a passing air bubble has been studied in a parallel plate flow chamber. Particle detachment decreased linearly with increasing air bubble velocity and

  11. Air bubble-induced detachment of positively and negatively charged polystyrene particles from collector surfaces in a parallel-plate flow chamber

    NARCIS (Netherlands)

    Gomez-Suarez, C; Van der Mei, HC; Busscher, HJ

    2000-01-01

    Electrostatic interactions between colloidal particles and collector surfaces were found tcr be important in particle detachment as induced by the passage of air bubbles in a parallel-plate Row chamber. Electrostatic interactions between adhering particles and passing air bubbles, however, a-ere

  12. Detachment of polystyrene particles from collector surfaces by surface tension forces induced by air-bubble passage through a parallel plate flow chamber

    NARCIS (Netherlands)

    Wit, PJ; vanderMei, HC; Busscher, HJ

    1997-01-01

    By allowing an air-bubble to pass through a parallel plate flow chamber with negatively charged, colloidal polystyrene particles adhering to the bottom collector plate of the chamber, the detachment of adhering particles stimulated by surface tension forces induced by the passage of a liquid-air

  13. Influence of shear on microbial adhesion to PEO-brushes and glass by convective-diffusion and sedimentation in a parallel plate flow chamber

    NARCIS (Netherlands)

    Roosjen, A; Boks, NP; van der Mei, HC; Busscher, HJ; Norde, W

    2005-01-01

    Microbial adhesion to surfaces often occurs despite high wall shear rates acting on the adhering microorganisms. In this paper, we compare the wall shear rates needed to prevent microbial adhesion to bare glass and poly(ethylene oxide) (PEO)-brush coated glass in a parallel plate flow chamber.

  14. Analysis of the contribution of sedimentation to bacterial mass transport in a parallel plate flow chamber Part II : Use of fluorescence imaging

    NARCIS (Netherlands)

    Li, Jiuyi; Busscher, Henk J.; van der Mei, Henny C.; Norde, Willem; Krom, Bastiaan P.; Sjollema, Jelmer

    2011-01-01

    Using a new phase-contrast microscopy-based method of analysis, sedimentation has recently been demonstrated to be the major mass transport mechanism of bacteria towards substratum surfaces in a parallel plate flow chamber (J. Li, H.J. Busscher, W. Norde, J. Sjollema, Colloid Surf. B. 84 (2011)76).

  15. Multilayer capacitors, method for making multilayer capacitors

    Science.gov (United States)

    Ma, Beihai; Balachandran, Uthamalingam

    2018-03-06

    The invention provides a stacked capacitor configuration comprising subunits each with a thickness of as low as 20 microns. Also provided is combination capacitor and printed wire board wherein the capacitor is encapsulated by the wire board. The invented capacitors are applicable in micro-electronic applications and high power applications, whether it is AC to DC or DC to AC, or DC to DC.

  16. Capacitor Discharge - A Capacitor Tutorial [video

    OpenAIRE

    Naval Postgraduate School Physics

    2014-01-01

    NPS Physics Physics Demonstrations Here's a capacitor discharge demonstrated by physicist Dr. Dernardo. Dr. D gives a nice capacitor lesson along with some fireworks. Charging and Discharging a Capacitor is dangerous. Do not try this at home. Dr. Bruce Denardo uses eleven 9V batteries, connected in series for a total of 99 creating a pretty large spark.

  17. Characterization of plasma jet ejected from a parallel-plate rail gun for simulating edge localized mode

    International Nuclear Information System (INIS)

    Chung, K.S.; Chung, Kyoung-Jae; Jung, B.K.; Hwang, Y.S.

    2013-01-01

    Highlights: • A small plasma gun is constructed to study edge localized mode. • A plasma jet ejected from the gun is characterized with a quadruple Langmuir probe. • The device and diagnostics are suitable for research about the control of plasma jet. -- Abstract: A small plasma gun with parallel-plate configuration is fabricated to generate a bunch of plasma which is similar to ELM (edge localized mode) plasma, by taking advantages of its simplicity and cost-effectiveness. Prior to explore how to control the ELM-like plasma so as to relieve heat load on the divertor target, characteristics of a plasma jet ejected from the plasma gun are investigated using a quadruple Langmuir probe which is appropriate for measuring rapidly varying plasma parameters such as electron density, temperature, and ion velocity at the same time. The plasma density and ion velocity measured at 112 mm away from the exit are 3 × 10 19 m −3 and 11 km/s, respectively, which seem to be suitable for investigating next step research on the control of ELM-like plasma using various methods such as electromagnetic waves and high-voltage pulses. Also, the quadruple Langmuir probe is proven to be adequate for use in such experiments

  18. Catalytic and Noncatalytic Conversion of Methane to Olefins and Synthesis Gas in an AC Parallel Plate Discharge Reactor

    Directory of Open Access Journals (Sweden)

    Mohammad Ali Khodagholi

    2013-01-01

    Full Text Available Direct conversion of methane to ethylene, acetylene, and synthesis gas at ambient pressure and temperature in a parallel plate discharge reactor was investigated. The experiments were carried out using a quartz reactor of outer diameter of 9 millimeter and a driving force of ac current of 50 Hz. The input power to the reactor to establish a stable gas discharge varied from 9.6 to maximum 15.3 watts (w. The effects of ZSM5, Fe–ZSM5, and Ni–ZSM5 catalysts combined with corona discharge for conversion of methane to more valued products have been addressed. It was found that in presence or absence of a catalyst in gas discharge reactor, the rate of methane and oxygen conversion increased upon higher input power supplied to the reactor. The effect of Fe–ZSM5 catalyst combined with gas discharge plasma yields C2 hydrocarbons up to 21.9%, which is the highest productions of C2 hydrocarbons in this work. The effect of combined Ni–ZSM5 and gas discharge plasma was mainly production of synthesis gas. The advantage of introducing ZSM5 to the plasma zone was increase in synthesis gas and acetylene production. The highest energy efficiency was 0.22 mmol/kJ, which belongs to lower rate of energy injection to the reactor.

  19. Characterization and Simulation of a New Design Parallel-Plate Ionization Chamber for CT Dosimetry at Calibration Laboratories

    Science.gov (United States)

    Perini, Ana P.; Neves, Lucio P.; Maia, Ana F.; Caldas, Linda V. E.

    2013-12-01

    In this work, a new extended-length parallel-plate ionization chamber was tested in the standard radiation qualities for computed tomography established according to the half-value layers defined at the IEC 61267 standard, at the Calibration Laboratory of the Instituto de Pesquisas Energéticas e Nucleares (IPEN). The experimental characterization was made following the IEC 61674 standard recommendations. The experimental results obtained with the ionization chamber studied in this work were compared to those obtained with a commercial pencil ionization chamber, showing a good agreement. With the use of the PENELOPE Monte Carlo code, simulations were undertaken to evaluate the influence of the cables, insulator, PMMA body, collecting electrode, guard ring, screws, as well as different materials and geometrical arrangements, on the energy deposited on the ionization chamber sensitive volume. The maximum influence observed was 13.3% for the collecting electrode, and regarding the use of different materials and design, the substitutions showed that the original project presented the most suitable configuration. The experimental and simulated results obtained in this work show that this ionization chamber has appropriate characteristics to be used at calibration laboratories, for dosimetry in standard computed tomography and diagnostic radiology quality beams.

  20. Casimir amplitudes and capillary condensation of near-critical fluids between parallel plates: renormalized local functional theory.

    Science.gov (United States)

    Okamoto, Ryuichi; Onuki, Akira

    2012-03-21

    We investigate the critical behavior of a near-critical fluid confined between two parallel plates in contact with a reservoir by calculating the order parameter profile and the Casimir amplitudes (for the force density and for the grand potential). Our results are applicable to one-component fluids and binary mixtures. We assume that the walls absorb one of the fluid components selectively for binary mixtures. We propose a renormalized local functional theory accounting for the fluctuation effects. Analysis is performed in the plane of the temperature T and the order parameter in the reservoir ψ(∞). Our theory is universal if the physical quantities are scaled appropriately. If the component favored by the walls is slightly poor in the reservoir, there appears a line of first-order phase transition of capillary condensation outside the bulk coexistence curve. The excess adsorption changes discontinuously between condensed and noncondensed states at the transition. With increasing T, the transition line ends at a capillary critical point T=T(c) (ca) slightly lower than the bulk critical temperature T(c) for the upper critical solution temperature. The Casimir amplitudes are larger than their critical point values by 10-100 times at off-critical compositions near the capillary condensation line. © 2012 American Institute of Physics

  1. Development of novel segmented-plate linearly tunable MEMS capacitors

    International Nuclear Information System (INIS)

    Shavezipur, M; Khajepour, A; Hashemi, S M

    2008-01-01

    In this paper, novel MEMS capacitors with flexible moving electrodes and high linearity and tunability are presented. The moving plate is divided into small and rigid segments connected to one another by connecting beams at their end nodes. Under each node there is a rigid step which selectively limits the vertical displacement of the node. A lumped model is developed to analytically solve the governing equations of coupled structural-electrostatic physics with mechanical contact. Using the analytical solver, an optimization program finds the best set of step heights that provides the highest linearity. Analytical and finite element analyses of two capacitors with three-segmented- and six-segmented-plate confirm that the segmentation technique considerably improves the linearity while the tunability remains as high as that of a conventional parallel-plate capacitor. Moreover, since the new designs require customized fabrication processes, to demonstrate the applicability of the proposed technique for standard processes, a modified capacitor with flexible steps designed for PolyMUMPs is introduced. Dimensional optimization of the modified design results in a combination of high linearity and tunability. Constraining the displacement of the moving plate can be extended to more complex geometries to obtain smooth and highly linear responses

  2. Characterizing the adhesion of motile and nonmotile Escherichia coli to a glass surface using a parallel-plate flow chamber.

    Science.gov (United States)

    McClaine, Jennifer W; Ford, Roseanne M

    2002-04-20

    A parallel-plate flow chamber was used to measure the attachment and detachment rates of Escherichia coli to a glass surface at various fluid velocities. The effect of flagella on adhesion was investigated by performing experiments with several E. coli strains: AW405 (motile); HCB136 (nonmotile mutant with paralyzed flagella); and HCB137 (nonmotile mutant without flagella). We compared the total attachment rates and the fraction of bacteria retained on the surface to determine how the presence and movement of the flagella influence transport to the surface and adhesion strength in this dynamic system. At the lower fluid velocities, there was no significant difference in the total attachment rates for the three bacterial strains; nonmotile strains settled at a rate that was of the same order of magnitude as the diffusion rate of the motile strain. At the highest fluid velocity, the effect of settling was minimized to better illustrate the importance of motility, and the attachment rates of both nonmotile strains were approximately five times slower than that of the motile bacteria. Thus, different processes controlled the attachment rate depending on the parameter regime in which the experiment was performed. The fractions of motile bacteria retained on the glass surface increased with increasing velocity, whereas the opposite trend was found for the nonmotile strains. This suggests that the rotation of the flagella enables cells to detach from the surface (at the lower fluid velocities) and strengthens adhesion (at higher fluid velocities), whereas nonmotile cells detach as a result of shear. There was no significant difference in the initial attachment rates of the two nonmotile species, which suggests that merely the presence of flagella was not important in this stage of biofilm development. Copyright 2002 Wiley Periodicals, Inc.

  3. Electric field and dielectrophoretic force on a dielectric particle chain in a parallel-plate electrode system

    International Nuclear Information System (INIS)

    Techaumnat, B; Eua-arporn, B; Takuma, T

    2004-01-01

    This paper presents results of calculations of the electric field and dielectrophoretic force on a dielectric particle chain suspended in a host liquid lying between parallel-plate electrodes. The method of calculation is based on the method of multipole images using the multipole re-expansion technique. We have investigated the effect of the particle permittivity, the tilt angle (between the chain and the applied field) and the chain arrangement on the electric field and force. The results show that the electric field intensification rises in accordance with the increase in the ratio of the particle-to-liquid permittivity, Γ ε . The electric field at the contact point between the particles decreases with increasing tilt angle, while the maximal field at the contact point between the particles and the plate electrodes is almost unchanged. The maximal field can be approximated by a simple formula, which is a quadratic function of Γ ε . The dielectrophoretic force depends significantly on the distance from other particles or an electrode. However, for the tilt angles in this paper, the horizontal force on the upper particle of the chain always has the direction opposite to the shear direction. The maximal horizontal force of a chain varies proportional to (Γ ε - 1) 1.7 if the particles in the chain are still in contact with each other. The approximated force, based on the force on an isolated chain, has been compared with our calculation results. The comparison shows that no approximation model agrees well with our results throughout the range of permittivity ratios

  4. Preparation of magnetorheological elastomers and their slip-free characterization by means of parallel-plate rotational rheometry

    Science.gov (United States)

    Walter, Bastian L.; Pelteret, Jean-Paul; Kaschta, Joachim; Schubert, Dirk W.; Steinmann, Paul

    2017-08-01

    A systematic study is presented to highlight a methodology of sample preparation and subsequent slip-free characterization of magnetorheological (MR) elastomers in parallel-plate rotational rheometry. Focusing on the magnetic field-dependent nonlinear viscoelastic behavior an array of oscillatory strain sweep measurements is conducted with samples cured within the rheometer. The examined nonlinear material response (i.e. the amplitude dependence of the storage and loss moduli) as a function of the applied magnetic field is found to be qualitatively similar to the amplitude dependence of particle reinforced elastomers (i.e. the Payne effect). Therefore, the experimental data (both moduli) is decomposed similar to that for reinforced elastomers and a phenomenological model is formulated for both the storage and loss modulus to account for the physical mechanisms governing the nonlinear material characteristics. Parameter identification suggests that the material response at low magnetic fields is dominated by the polymeric network whereas the strong magneto-reinforced microstructure governs the linear and nonlinear viscoelastic behavior at high magnetic fields. The overall experimental outcome further suggests that the underlying concept of the phenomenological model for particle reinforced elastomers (i.e. destruction and reformation of the filler network) can be transfered to MR materials. Consequently, the proposed phenomenological model can be applied to quantify and further analyze the nonlinear response characteristics of MR elastomers (i.e. the amplitude dependence of the storage and loss modulus as a function of the applied magnetic field) that is closely linked to microstructural changes of the magnetizable particle network.

  5. A multi-component parallel-plate flow chamber system for studying the effect of exercise-induced wall shear stress on endothelial cells.

    Science.gov (United States)

    Wang, Yan-Xia; Xiang, Cheng; Liu, Bo; Zhu, Yong; Luan, Yong; Liu, Shu-Tian; Qin, Kai-Rong

    2016-12-28

    In vivo studies have demonstrated that reasonable exercise training can improve endothelial function. To confirm the key role of wall shear stress induced by exercise on endothelial cells, and to understand how wall shear stress affects the structure and the function of endothelial cells, it is crucial to design and fabricate an in vitro multi-component parallel-plate flow chamber system which can closely replicate exercise-induced wall shear stress waveforms in artery. The in vivo wall shear stress waveforms from the common carotid artery of a healthy volunteer in resting and immediately after 30 min acute aerobic cycling exercise were first calculated by measuring the inner diameter and the center-line blood flow velocity with a color Doppler ultrasound. According to the above in vivo wall shear stress waveforms, we designed and fabricated a parallel-plate flow chamber system with appropriate components based on a lumped parameter hemodynamics model. To validate the feasibility of this system, human umbilical vein endothelial cells (HUVECs) line were cultured within the parallel-plate flow chamber under abovementioned two types of wall shear stress waveforms and the intracellular actin microfilaments and nitric oxide (NO) production level were evaluated using fluorescence microscope. Our results show that the trends of resting and exercise-induced wall shear stress waveforms, especially the maximal, minimal and mean wall shear stress as well as oscillatory shear index, generated by the parallel-plate flow chamber system are similar to those acquired from the common carotid artery. In addition, the cellular experiments demonstrate that the actin microfilaments and the production of NO within cells exposed to the two different wall shear stress waveforms exhibit different dynamic behaviors; there are larger numbers of actin microfilaments and higher level NO in cells exposed in exercise-induced wall shear stress condition than resting wall shear stress condition

  6. Nanohybrid capacitor: the next generation electrochemical capacitors

    Energy Technology Data Exchange (ETDEWEB)

    Naoi, K. [Institute of Symbiotic Science and Technology, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo 184-8558 (Japan)

    2010-10-15

    Conventional electric double layer capacitors (EDLC) designed with two symmetrical activated carbon electrodes can deliver substantially more power than similar size Li-ion batteries. There is presently a major effort to increase the energy density of EDLC s up to a target value in the vicinity of 20-30 Wh kg{sup -1}.The present review article deals with the recent contributions to get this high energy density and new approaches that have been made to increase the withstanding voltage of the EDLCs. Important alternative approach to meet this goal that is under serious investigation is to develop an asymmetric (hybrid) capacitors. Hybrid capacitor systems are the promising approach to meet the goal to effectively increase the energy density. The investigation is to develop hybrid capacitors has been initiated by Li-ion capacitors. And, now Nanohybrid capacitor certainly achieves as high energy density as Li-ion capacitors with higher stability, higher safety and higher productivity. This is the new lithium-ion based hybrid capacitor using the lithium titanate (Li{sub 4}Ti{sub 5}O{sub 12}) negative intercalation electrode that can operate at unusually high current densities. The high-rate Li{sub 4}Ti{sub 5}O{sub 12} negative electrode has a unique nano-structure consisting of unusually small nano-crystalline Li{sub 4}Ti{sub 5}O{sub 12} nucleated and grafted onto carbon nano-fiber anchors (nc-Li{sub 4}Ti{sub 5}O{sub 12}/CNF). (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  7. Capacitor Property and Leakage Current Mechanism of ZrO2 Thin Dielectric Films Prepared by Anodic Oxidation

    Science.gov (United States)

    Kamijyo, Masahiro; Onozuka, Tomotake; Shinkai, Satoko; Sasaki, Katsutaka; Yamane, Misao; Abe, Yoshio

    2003-07-01

    Polycrystalline ZrO2 thin film capacitors were prepared by anodizing sputter-deposited Zr films. Electrical measurements are performed for the parallel-plate anodized capacitors with an Al-ZrO2-Zr (metal-insulator-metal) structure, and a high capacitance density (0.6 μF/cm2) and a low dielectric loss of nearly 1% are obtained for a very thin-oxide capacitor anodized at 10 V. In addition, the leakage current density of this capacitor is about 1.8 × 10-8 A/cm2 at an applied voltage of 5 V. However, the leakage current is somewhat larger than that of a low-loss HfO2 capacitor. The leakage current density (J) of ZrO2 capacitors as a function of applied electric field (E) was investigated for several capacitors with different oxide thicknesses, by plotting \\ln(J) vs E1/2 curves. As a result, it is revealed that the conduction mechanism is due to the Poole-Frenkel effect, irrespective of the oxide thickness.

  8. Application of particle image velocimetry measurement techniques to study turbulence characteristics of oscillatory flows around parallel-plate structures in thermoacoustic devices

    International Nuclear Information System (INIS)

    Mao, Xiaoan; Jaworski, Artur J

    2010-01-01

    This paper describes the development of the experimental setup and measurement methodologies to study the physics of oscillatory flows in the vicinity of parallel-plate stacks by using the particle image velocimetry (PIV) techniques. Parallel-plate configurations often appear as internal structures in thermoacoustic devices and are responsible for the hydrodynamic energy transfer processes. The flow around selected stack configurations is induced by a standing acoustic wave, whose amplitude can be varied. Depending on the direction of the flow within the acoustic cycle, relative to the stack, it can be treated as an entrance flow or a wake flow. The insight into the flow behaviour, its kinematics, dynamics and scales of turbulence, is obtained using the classical Reynolds decomposition to separate the instantaneous velocity fields into ensemble-averaged mean velocity fields and fluctuations in a set of predetermined phases within an oscillation cycle. The mean velocity field and the fluctuation intensity distributions are investigated over the acoustic oscillation cycle. The velocity fluctuation is further divided into large- and small-scale fluctuations by using fast Fourier transform (FFT) spatial filtering techniques

  9. Investigation and performance tests of a new parallel plate ionization chamber with double sensitive volume for measuring diagnostic X-rays

    Energy Technology Data Exchange (ETDEWEB)

    Sharifi, B., E-mail: babak_sharifi88@yahoo.com [Graduate University of Advanced Technology, Kerman (Iran, Islamic Republic of); Zamani Zeinali, H. [Application of Radiation Research School, Nuclear Science and Technology Research Institute, AEOI, Karaj (Iran, Islamic Republic of); Soltani, J.; Negarestani, A. [Graduate University of Advanced Technology, Kerman (Iran, Islamic Republic of); Shahvar, A. [Application of Radiation Research School, Nuclear Science and Technology Research Institute, AEOI, Karaj (Iran, Islamic Republic of)

    2015-01-11

    Medical diagnostic equipment, like diagnostic radiology and mammography require a dosimeter with high accuracy for dosimetry of the diagnostic X-ray beam. Ionization chambers are suitable instruments for dosimetry of diagnostic-range X-ray beams because of their appropriate response and high reliability. This work introduces the design and fabrication of a new parallel plate ionization chamber with a PMMA body, graphite-coated PMMA windows (0.5 mm thick) and a graphite-foil central electrode (0.1 mm thick, 0.7 g/cm{sup 3} dense). This design improves upon the response characteristics of existing designs through the specific choice of materials as well as the appropriate size and arrangement of the ionization chamber components. The results of performance tests conducted at the Secondary Standard Dosimetry laboratory in Karaj-Iran demonstrated the short and long-term stability, the low leakage current, the low directional dependence, and the high ion collection efficiency of the design. Furthermore, the FLUKA Monte Carlo simulations confirmed the low effect of central electrode on this new ionization chamber response. The response characteristics of the parallel plate ionization chamber presented in this work makes the instrument suitable for use as a standard dosimeter in laboratories.

  10. Some studies on the pulse-height loss due to capacitive decay in the detector-circuit of parallel plate ionization chambers

    International Nuclear Information System (INIS)

    Sharma, S.L.; Anil Kumar, G.; Choudhury, R.K.

    2006-01-01

    Pulse-type ionization chambers are invariably operated in the electron-sensitive mode where the capacitive decay in the detector-circuit during the electron collection produces loss in the pulse-height. In order to understand and appreciate the effect of this capacitive decay on the detector response, we have carried out Monte Carlo simulations of the response of two-electrode parallel plate ionization chambers with and without the capacitive decay keeping shaping time so large that the ballistic deficit is negligibly small. These simulations have been carried out incorporating the physical processes, namely, emission of charged particles from a point radioactive source, the generation of charge carriers in the active volume, separation and acceleration of the charge carriers, transport of the charge carriers, induction of charges on the electrodes, pulse processing by preamplifier-amplifier network, etc. These simulations have shown that the concerned capacitive decay produces appreciable loss in the pulse-height, if the detector-circuit time constant is of the order of maximum electron collection time. We have also carried out measurements on the pulse-height loss due to the capacitive decay in the detector-circuit during the electron collection for a two-electrode parallel plate ionization chamber. The experimental data on the pulse-height loss match reasonably well with the theoretical predictions

  11. PPC's (parallel plate chambers) y su aplicación en calorimetría a bajo angulo en experimentos en el LHC

    CERN Document Server

    Fouz-Iglesias, M C

    1997-01-01

    In the LHC working conditions especific detector requirements are fast response, high rate capability and radiation resistance. This is particularly important for detectors in the low angle regions such as the Very Forward Hadron Calorimeter ( VF ) of CMS , located at 11 m from the interaction point and covering the pseudorapidity region between 3 and 5. The major goals of this calorimeters are to improve the measured of the transverse energy ( Et) and the missing transverse energy ( Etmiss) ( important for Higgs searches, Top-quark physics, SUSY searches, etc) and the detection and reconstruction of forward jets characteristics of some importants process (such the TeV jets coming from the WW(ZZ) fusion Higgs production mechanism ). The requirements for this calorimeter are a moderate energy resolution and an adequate segmentation for forward jet tagging and reconstruction are needed. The purpose of this thesis is to show that calorimeters based on the Parallel Plate Chambers ( PPC. - Gaseous detector with pl...

  12. Adomian decomposition method for Hall and ion-slip effects on mixed convection flow of a chemically reacting Newtonian fluid between parallel plates with heat generation/absorption

    Directory of Open Access Journals (Sweden)

    Ch.Ram Reddy

    2017-12-01

    Full Text Available This paper analyzes the heat and mass transfer characteristics on mixed convective fully developed flow in an electrically conducting Newtonian fluid between vertical parallel plates. The chemical reaction, heat generation, Hall and ion-slip effects are taken into consideration. By using similarity transformations the nonlinear governing equations are reduced into dimensionless form and hence solved using Adomian decomposition method (ADM. The influence of magnetic parameter, Hall parameter, ion-slip parameter, chemical reaction parameter, and heat generation/absorption parameter on non-dimensional velocities, temperature and concentration profiles are exhibited graphically. In addition, the numerical data for skin friction, heat and mass transfer rates are shown in tabular form.

  13. A Novel Method for Measurements of the Penetration Depth of MgB2 Superconductor Films by Using Sapphire Resonators with Short-Circuited Parallel Plates

    International Nuclear Information System (INIS)

    Jung, Ho Sang; Lee, J. H.; Cho, Y. H.; Lee, Sang Young; Seong, W. K.; Lee, N. H.; Kang, W. N.

    2009-01-01

    We introduce a measurement method that enables to measure the penetration depth(λ) of superconductor films by using a short-ended parallel plate sapphire resonator. Variations in the (λof MgB 2 films could be measured down to the lowest temperature using a sapphire resonator with a YBa 2 Cu 3 O 7-x film at the bottom. A model equation of λλ 0 [1-(T/T c ) τ ] -1/2 for MgB 2 films appeared to describe the observed variations of the resonant frequency of the sapphire resonator with temperature, with λ 0 , τ and T c used as the fitting parameters.

  14. Retrieval of the thickness and refractive index dispersion of parallel plate from a single interferogram recorded in both spectral and angular domains

    Science.gov (United States)

    Dong, Jingtao; Lu, Rongsheng

    2018-04-01

    The principle of retrieving the thickness and refractive index dispersion of a parallel glass plate is reported based on single interferogram recording and phase analysis. With the parallel plate illuminated by a convergent light sheet, the transmitted light interfering in both spectral and angular domains is recorded. The phase recovered from the single interferogram by Fourier analysis is used to retrieve the thickness and refractive index dispersion without periodic ambiguity. Experimental results of an optical substrate standard show that the accuracy of refractive index dispersion is less than 2.5 × 10-5 and the relative uncertainty of thickness is 6 × 10-5 (3σ). This method is confirmed to be robust against the intensity noises, indicating the capability of stable and accurate measurement.

  15. Capacitor discharge engineering

    CERN Document Server

    Früngel, Frank B A

    1976-01-01

    High Speed Pulse Technology, Volume III: Capacitor Discharge Engineering covers the production and practical application of capacitor dischargers for the generation and utilization of high speed pulsed of energy in different forms. This nine-chapter volume discusses the principles of electric current, voltage, X-rays, gamma rays, heat, beams of electrons, neutrons and ions, magnetic fields, sound, and shock waves in gases and liquids. Considerable chapters consider the applications of capacitor discharges, such as impulse hardening of steel, ultrapulse welding of precision parts, X-ray flash t

  16. Suspended graphene variable capacitor

    OpenAIRE

    AbdelGhany, M.; Mahvash, F.; Mukhopadhyay, M.; Favron, A.; Martel, R.; Siaj, M.; Szkopek, T.

    2016-01-01

    The tuning of electrical circuit resonance with a variable capacitor, or varactor, finds wide application with the most important being wireless telecommunication. We demonstrate an electromechanical graphene varactor, a variable capacitor wherein the capacitance is tuned by voltage controlled deflection of a dense array of suspended graphene membranes. The low flexural rigidity of graphene monolayers is exploited to achieve low actuation voltage in an ultra-thin structure. Large arrays compr...

  17. Materials for electrochemical capacitors

    Science.gov (United States)

    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.

  18. Effects of post-deposition oxygen annealing on tuning properties of Ba0.8Sr0.2TiO3 thin-film capacitors for microwave integrated circuits

    International Nuclear Information System (INIS)

    Liu, Y.R.; Lai, P.T.; Li, G.Q.; Li, B.; Peng, J.B.; Lo, H.B.

    2005-01-01

    Barium strontium titanate (BST) thin-films deposited on a SiO 2 /Si substrate by argon ion-beam sputtering technique were annealed at 400, 500 and 600 deg. C in oxygen for 30 min, respectively, and were used to fabricate integrated parallel-plate capacitors by standard integrated-circuit technology. These capacitors can achieve tunability greater than 60% at an applied dc voltage of 2 V and a frequency of 100 kHz at room temperature. Considering tunability, loss factor and hysteresis effect, the BST thin-film annealed at 500 deg. C is superior for making tunable microwave integrated capacitors. The effects of annealing treatment in oxygen on the tuning properties of the thin-film capacitors are analyzed, and the results indicate that the tunability is strongly dependent on both oxygen vacancies and negatively charged oxygen, trapped at the grain boundary and/or at the electrode/dielectric interface

  19. Study of the microstructural evolution and rheological behavior by semisolid compression between parallel plate of the alloy A356 solidified under a continuously rotating magnetic field

    International Nuclear Information System (INIS)

    Leiva L, Ricardo; Sanchez V, Cristian; Mannheim C, Rodolfo; Bustos C, Oscar

    2004-01-01

    This work presents a study of the rheological behavior of the alloy A356, with and without continuous magnetic agitation during its solidification, in semisolid state. The evaluation was performed using a parallel plate compression rheometer with the digital recording of position and time data. The microstructural evolution was also studied at the start and end of the semisolid compression test. The procedure involved tests of short cylinders extracted from billets with a non dendritic microstructure cast under a continuously rotating magnetic field. These pieces were tested in different solid fractions, at constant charges and at constant deformation velocities. When the test is carried out at a constant charge the equation can be determined that governs the rheological behavior of the material in semisolid state following a power grade of two Ostwald-de-Waele parameters. But when the test is done at a constant deformation speed the flow behavior of the material can be described in the semisolid shaping process. The results obtained show that the morphology of the phases present in the microstructure is highly relevant to its rheological behavior. A globular coalesced rosette to rosette type microstructure was found to have the typical behavior of a fluid when shaped in a semisolid state but a cast dendritic structure did not behave this way. Also the Arrhenius type dependence of viscosity with temperature was established (CW)

  20. Parallel-plate third sound waveguides with fixed and variable plate spacings for the study of fifth sound in superfluid helium

    International Nuclear Information System (INIS)

    Jelatis, G.J.

    1983-01-01

    Third sound in superfluid helium four films has been investigated using two parallel-plate waveguides. These investigations led to the observation of fifth sound, a new mode of sound propagation. Both waveguides consisted of two parallel pieces of vitreous quartz. The sound speed was obtained by measuring the time-of-flight of pulsed third sound over a known distance. Investigations from 1.0-1.7K were possible with the use of superconducting bolometers, which measure the temperature component of the third sound wave. Observations were initially made with a waveguide having a plate separation fixed at five microns. Adiabatic third sound was measured in the geometry. Isothermal third sound was also observed, using the usual, single-substrate technique. Fifth sound speeds, calculated from the two-fluid theory of helium and the speeds of the two forms of third sound, agreed in size and temperature dependence with theoretical predictions. Nevertheless, only equivocal observations of fifth sound were made. As a result, the film-substrate interaction was examined, and estimates of the Kapitza conductance were made. Assuming the dominance of the effects of this conductance over those due to the ECEs led to a new expression for fifth sound. A reanalysis of the initial data was made, which contained no adjustable parameters. The observation of fifth sound was seen to be consistent with the existence of an anomalously low boundary conductance

  1. Convective heat transfer for a gaseous slip flow in micropipe and parallel-plate microchannel with uniform wall heat flux: effect of axial heat conduction

    Science.gov (United States)

    Haddout, Y.; Essaghir, E.; Oubarra, A.; Lahjomri, J.

    2018-06-01

    Thermally developing laminar slip flow through a micropipe and a parallel plate microchannel, with axial heat conduction and uniform wall heat flux, is studied analytically by using a powerful method of self-adjoint formalism. This method results from a decomposition of the elliptic energy equation into a system of two first-order partial differential equations. The advantage of this method over other methods, resides in the fact that the decomposition procedure leads to a selfadjoint problem although the initial problem is apparently not a self-adjoint one. The solution is an extension of prior studies and considers a first order slip model boundary conditions at the fluid-wall interface. The analytical expressions for the developing temperature and local Nusselt number in the thermal entrance region are obtained in the general case. Therefore, the solution obtained could be extended easily to any hydrodynamically developed flow and arbitrary heat flux distribution. The analytical results obtained are compared for select simplified cases with available numerical calculations and they both agree. The results show that the heat transfer characteristics of flow in the thermal entrance region are strongly influenced by the axial heat conduction and rarefaction effects which are respectively characterized by Péclet and Knudsen numbers.

  2. Determination of absorbed dose to water from a miniature kilovoltage x-ray source using a parallel-plate ionization chamber

    Science.gov (United States)

    Watson, Peter G. F.; Popovic, Marija; Seuntjens, Jan

    2018-01-01

    Electronic brachytherapy sources are widely accepted as alternatives to radionuclide-based systems. Yet, formal dosimetry standards for these devices to independently complement the dose protocol provided by the manufacturer are lacking. This article presents a formalism for calculating and independently verifying the absorbed dose to water from a kV x-ray source (The INTRABEAM System) measured in a water phantom with an ionization chamber calibrated in terms of air-kerma. This formalism uses a Monte Carlo (MC) calculated chamber conversion factor, CQ , to convert air-kerma in a reference beam to absorbed dose to water in the measurement beam. In this work CQ was determined for a PTW 34013 parallel-plate ionization chamber. Our results show that CQ was sensitive to the chamber plate separation tolerance, with differences of up to 15%. CQ was also found to have a depth dependence which varied with chamber plate separation (0 to 10% variation for the smallest and largest cavity height, over 3 to 30 mm depth). However for all chamber dimensions investigated, CQ was found to be significantly larger than the manufacturer reported value, suggesting that the manufacturer recommended method of dose calculation could be underestimating the dose to water.

  3. A Controller For The Three-phase To Three-phase Matrix Converter And For The Voltage Source Three-phase Inverter Without Dc-link Capacitor [um Controlador De Corrente De Carga Para O Conversor Em Matriz Trifásico Para Trifásico E Para O Inversor De Frequência Sem Capacitor Do Elo De Corrente Contínua

    OpenAIRE

    Filho M.E.O.; Gazoli J.R.; Filho A.J.S.; Ruppert E.

    2010-01-01

    Voltage source three-phase inverter plays an important role in modern industry. The conventional voltage source inverter has a large electrolytic capacitor as energy store element in order to keep the DC-link voltage constant. However, a large electrolytic capacitor increases the input current distortion. Replacing the large electrolytic capacitor by a small film capacitor, the input current quality is improved but the DC-link voltage and the output currents are distorted by low order harmoni...

  4. Parallel plate transmission line transformer

    NARCIS (Netherlands)

    Voeten, S.J.; Brussaard, G.J.H.; Pemen, A.J.M.

    2011-01-01

    A Transmission Line Transformer (TLT) can be used to transform high-voltage nanosecond pulses. These transformers rely on the fact that the length of the pulse is shorter than the transmission lines used. This allows connecting the transmission lines in parallel at the input and in series at the

  5. Electrically tuned super-capacitors

    OpenAIRE

    Chowdhury, Tazima S.; Grebel, Haim

    2015-01-01

    Fast charging and discharging of large amounts of electrical energy make super-capacitors ideal for short-term energy storage [1-5]. In its simplest form, the super-capacitor is an electrolytic capacitor made of an anode and a cathode immersed in an electrolyte. As for an ordinary capacitor, minimizing the charge separation distance and increasing the electrode area increase capacitance. In super-capacitors, charge separation is of nano-meter scale at each of the electrode interface (the Helm...

  6. Epitaxial Al2O3 capacitors for low microwave loss superconducting quantum circuits

    Directory of Open Access Journals (Sweden)

    K.-H. Cho

    2013-10-01

    Full Text Available We have characterized the microwave loss of high-Q parallel plate capacitors fabricated from thin-film Al/Al2O3/Re heterostructures on (0001 Al2O3 substrates. The superconductor-insulator-superconductor trilayers were grown in situ in a hybrid deposition system: the epitaxial Re base and polycrystalline Al counterelectrode layers were grown by sputtering, while the epitaxial Al2O3 layer was grown by pulsed laser deposition. Structural analysis indicates a highly crystalline epitaxial Al2O3 layer and sharp interfaces. The measured intrinsic (low-power, low-temperature quality factor of the resonators is as high as 3 × 104. These results indicate that low-loss grown Al2O3 is an attractive candidate dielectric for high-fidelity superconducting qubit circuits.

  7. Nano-structured variable capacitor based on P(VDF-TrFE) copolymer and carbon nanotubes

    Science.gov (United States)

    Lakbita, I.; El-Hami, K.

    2018-02-01

    A newly organic capacitor was conceived with a variable capacitance using the inverse piezoelectric effect. The device consists of two parallel plates of carbon nanotubes (CNTs), known for their large surface area, high sensitivity and high electric conductivity, separated by a thin film of a dielectric layer of Polyinylidene fluoride and trifluoroehtylene (P(VDF-TrFE)) promising material for piezoelectric and ferroelectric properties. The obtained architecture is the CNT/PVDF-TrFE/CNT capacitor device. In this study, an ultra-thin film of P(VDF-TrFE) (54/46) with thickness of 20 nm was elaborated on highly oriented pyrolytic graphite (HOPG) by spin-coating. The morphology of the ultra-thin film and the mechanical behavior of CNT/P(VDF-TrFE)/CNT system were studied using the atomic force microscopy (AFM) combined with a lock-in amplifier in contact mode. All changes in applied voltage induce a change in thin film thickness according to the inverse piezoelectric effect that affect, consequently the capacitance. The results showed that the ratio of capacitance change ΔC to initial capacitance C0 is ΔC/C0=5%. This value is sufficient to use P(VDF-TrFE) as variable organic capacitor.

  8. Mechanical states in wound capacitors

    International Nuclear Information System (INIS)

    Allen, J.J.; Reuter, R.C. Jr.

    1989-01-01

    The winding process is encountered frequently in manufacturing, such as winding of polymer films and paper, laminated pressure vessel construction, and the manufacture of wound capacitors. The winding of capacitors will typically involve hundreds of plies of conductor and dielectric wound over a core. Due to the large number of layers, the calculation of the mechanical studies within a wound capacitor is a significant computational task. The focus of Part II of this paper is the formulation and application of optimization techniques for the design of wound capacitors. The design criteria to be achieved is a specified uniform wound tension in a capacitor. The paper will formulate an optimization statement of the wound capacitor design problem, develop a technique for reducing the numerical calculation required to repeatedly analyze the capacitor as required by the optimization algorithm, and apply the technique to an example. 4 refs., 13 figs., 4 tabs

  9. Capacitor assembly and related method of forming

    Science.gov (United States)

    Zhang, Lili; Tan, Daniel Qi; Sullivan, Jeffrey S.

    2017-12-19

    A capacitor assembly is disclosed. The capacitor assembly includes a housing. The capacitor assembly further includes a plurality of capacitors disposed within the housing. Furthermore, the capacitor assembly includes a thermally conductive article disposed about at least a portion of a capacitor body of the capacitors, and in thermal contact with the capacitor body. Moreover, the capacitor assembly also includes a heat sink disposed within the housing and in thermal contact with at least a portion of the housing and the thermally conductive article such that the heat sink is configured to remove heat from the capacitor in a radial direction of the capacitor assembly. Further, a method of forming the capacitor assembly is also presented.

  10. Fractal Structures For Mems Variable Capacitors

    KAUST Repository

    Elshurafa, Amro M.; Radwan, Ahmed Gomaa Ahmed; Emira, Ahmed A.; Salama, Khaled N.

    2014-01-01

    In accordance with the present disclosure, one embodiment of a fractal variable capacitor comprises a capacitor body in a microelectromechanical system (MEMS) structure, wherein the capacitor body has an upper first metal plate with a fractal shape

  11. Investigation of embedded perovskite nanoparticles for enhanced capacitor permittivities.

    Science.gov (United States)

    Krause, Andreas; Weber, Walter M; Pohl, Darius; Rellinghaus, Bernd; Verheijen, Marcel; Mikolajick, Thomas

    2014-11-26

    Growth experiments show significant differences in the crystallization of ultrathin CaTiO3 layers on polycrystalline Pt surfaces. While the deposition of ultrathin layers below crystallization temperature inhibits the full layer crystallization, local epitaxial growth of CaTiO3 crystals on top of specific oriented Pt crystals occurs. The result is a formation of crystals embedded in an amorphous matrix. An epitaxial alignment of the cubic CaTiO3 ⟨111⟩ direction on top of the underlying Pt {111} surface has been observed. A reduced forming energy is attributed to an interplay of surface energies at the {111} interface of both materials and CaTiO3 nanocrystallites facets. The preferential texturing of CaTiO3 layers on top of Pt has been used in the preparation of ultrathin metal-insulator-metal capacitors with 5-30 nm oxide thickness. The effective CaTiO3 permittivity in the capacitor stack increases to 55 compared to capacitors with amorphous layers and a permittivity of 28. The isolated CaTiO3 crystals exhibit a passivation of the CaTiO3 grain surfaces by the surrounding amorphous matrix, which keeps the capacitor leakage current at ideally low values comparable for those of amorphous thin film capacitors.

  12. A Simple, Successful Capacitor Lab

    Science.gov (United States)

    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.

  13. Protection of large capacitor banks

    International Nuclear Information System (INIS)

    Sprott, J.C.; Lovell, T.W.

    1982-06-01

    Large capacitor banks, as used in many pulsed plasma experiments, are subject to catastrophic failure in the event of a short in the output or in an individual capacitor. Methods are described for protecting such banks to minimize the damage and down-time caused by such a failure

  14. Comparison of electron transmittances and tunneling currents in an anisotropic TiNx/HfO2/SiO2/p-Si(100) metal-oxide-semiconductor (MOS) capacitor calculated using exponential- and Airy-wavefunction approaches and a transfer matrix method

    International Nuclear Information System (INIS)

    Noor, Fatimah A.; Abdullah, Mikrajuddin; Sukirno; Khairurrijal

    2010-01-01

    Analytical expressions of electron transmittance and tunneling current in an anisotropic TiN x /HfO 2 /SiO 2 /p-Si(100) metal-oxide-semiconductor (MOS) capacitor were derived by considering the coupling of transverse and longitudinal energies of an electron. Exponential and Airy wavefunctions were utilized to obtain the electron transmittance and the electron tunneling current. A transfer matrix method, as a numerical approach, was used as a benchmark to assess the analytical approaches. It was found that there is a similarity in the transmittances calculated among exponential- and Airy-wavefunction approaches and the TMM at low electron energies. However, for high energies, only the transmittance calculated by using the Airy-wavefunction approach is the same as that evaluated by the TMM. It was also found that only the tunneling currents calculated by using the Airy-wavefunction approach are the same as those obtained under the TMM for all range of oxide voltages. Therefore, a better analytical description for the tunneling phenomenon in the MOS capacitor is given by the Airy-wavefunction approach. Moreover, the tunneling current density decreases as the titanium concentration of the TiN x metal gate increases because the electron effective mass of TiN x decreases with increasing nitrogen concentration. In addition, the mass anisotropy cannot be neglected because the tunneling currents obtained under the isotropic and anisotropic masses are very different. (semiconductor devices)

  15. Split-phase motor running as capacitor starts motor and as capacitor run motor

    Directory of Open Access Journals (Sweden)

    Yahaya Asizehi ENESI

    2016-07-01

    Full Text Available In this paper, the input parameters of a single phase split-phase induction motor is taken to investigate and to study the output performance characteristics of capacitor start and capacitor run induction motor. The value of these input parameters are used in the design characteristics of capacitor run and capacitor start motor with each motor connected to rated or standard capacitor in series with auxiliary winding or starting winding respectively for the normal operational condition. The magnitude of capacitor that will develop maximum torque in capacitor start motor and capacitor run motor are investigated and determined by simulation. Each of these capacitors is connected to the auxiliary winding of split-phase motor thereby transforming it into capacitor start or capacitor run motor. The starting current and starting torque of the split-phase motor (SPM, capacitor run motor (CRM and capacitor star motor (CSM are compared for their suitability in their operational performance and applications.

  16. Fractal Structures For Mems Variable Capacitors

    KAUST Repository

    Elshurafa, Amro M.

    2014-08-28

    In accordance with the present disclosure, one embodiment of a fractal variable capacitor comprises a capacitor body in a microelectromechanical system (MEMS) structure, wherein the capacitor body has an upper first metal plate with a fractal shape separated by a vertical distance from a lower first metal plate with a complementary fractal shape; and a substrate above which the capacitor body is suspended.

  17. Polyvinylidene fluoride film as a capacitor dielectric

    Science.gov (United States)

    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.

  18. Ferroelectric Fractional-Order Capacitors

    KAUST Repository

    Agambayev, Agamyrat

    2017-07-25

    Poly(vinylidene fluoride)-based polymers and their blends are used to fabricate electrostatic fractional-order capacitors. This simple but effective method allows us to precisely tune the constant phase angle of the resulting fractional-order capacitor by changing the blend composition. Additionally, we have derived an empirical relation between the ratio of the blend constituents and the constant phase angle to facilitate the design of a fractional order capacitor with a desired constant phase angle. The structural composition of the fabricated blends is investigated using Fourier transform infrared spectroscopy and X-ray diffraction techniques.

  19. Ferroelectric Fractional-Order Capacitors

    KAUST Repository

    Agambayev, Agamyrat; Patole, Shashikant P.; Farhat, Mohamed; Elwakil, Ahmed; Bagci, Hakan; Salama, Khaled N.

    2017-01-01

    Poly(vinylidene fluoride)-based polymers and their blends are used to fabricate electrostatic fractional-order capacitors. This simple but effective method allows us to precisely tune the constant phase angle of the resulting fractional-order capacitor by changing the blend composition. Additionally, we have derived an empirical relation between the ratio of the blend constituents and the constant phase angle to facilitate the design of a fractional order capacitor with a desired constant phase angle. The structural composition of the fabricated blends is investigated using Fourier transform infrared spectroscopy and X-ray diffraction techniques.

  20. Fractal Structures For Fixed Mems Capacitors

    KAUST Repository

    Elshurafa, Amro M.

    2014-08-28

    An embodiment of a fractal fixed capacitor comprises a capacitor body in a microelectromechanical system (MEMS) structure. The capacitor body has a first plate with a fractal shape separated by a horizontal distance from a second plate with a fractal shape. The first plate and the second plate are within the same plane. Such a fractal fixed capacitor further comprises a substrate above which the capacitor body is positioned.

  1. Fractal Structures For Fixed Mems Capacitors

    KAUST Repository

    Elshurafa, Amro M.; Radwan, Ahmed Gomaa Ahmed; Emira, Ahmed A.; Salama, Khaled N.

    2014-01-01

    An embodiment of a fractal fixed capacitor comprises a capacitor body in a microelectromechanical system (MEMS) structure. The capacitor body has a first plate with a fractal shape separated by a horizontal distance from a second plate with a fractal shape. The first plate and the second plate are within the same plane. Such a fractal fixed capacitor further comprises a substrate above which the capacitor body is positioned.

  2. Ferroelectric capacitor with reduced imprint

    Science.gov (United States)

    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.

  3. Mutual capacitor and its applications

    Directory of Open Access Journals (Sweden)

    Chun Li

    2014-06-01

    Full Text Available This study presents a new ac circuit element – the mutual capacitor, being a dual of the mutual inductor, which is also a new ac transformer. This element is characteristic of the mutual-capacitance coupling of a multi-capacitance system. A unity-coupled mutual capacitor works as an ideal current or voltage transformer, and incidentally acts as waveform separating when inductor employed or waveform converting from square-wave to quasi-sine or waveform filtering, between ports. As a transformer, the mutual capacitor is easy to design, easy for heat cooling, more accurate for current or voltage transformation, dissipating less energy as well as saving materials, suitable for high-power and high-voltage applications. Experiments to demonstrate performances of unity-coupled mutual capacitors are also given.

  4. Force on an Asymmetric Capacitor

    National Research Council Canada - National Science Library

    Bahder, Thomas

    2003-01-01

    .... At present, the physical basis for the Biefeld-Brown effect is not understood. The order of magnitude of the net force on the asymmetric capacitor is estimated assuming two different mechanisms of charge conduction between its electrodes...

  5. High density energy storage capacitor

    International Nuclear Information System (INIS)

    Whitham, K.; Howland, M.M.; Hutzler, J.R.

    1979-01-01

    The Nova laser system will use 130 MJ of capacitive energy storage and have a peak power capability of 250,000 MW. This capacitor bank is a significant portion of the laser cost and requires a large portion of the physical facilities. In order to reduce the cost and volume required by the bank, the Laser Fusion Program funded contracts with three energy storage capacitor producers: Aerovox, G.E., and Maxwell Laboratories, to develop higher energy density, lower cost energy storage capacitors. This paper describes the designs which resulted from the Aerovox development contract, and specifically addresses the design and initial life testing of a 12.5 kJ, 22 kV capacitor with a density of 4.2 J/in 3 and a projected cost in the range of 5 cents per joule

  6. Efficiency Improvement of Capacitor Operation

    Directory of Open Access Journals (Sweden)

    V. P. Kashcheev

    2010-01-01

    Full Text Available A system of modernized capacitor ball-cleaning that prevents formation of depositions on internal capacitor tube surface has been developed in the paper.The system has been introduced at the Minsk TPP-4 (Power Block No.5. The paper presupposes that the economic effect will be nearly 0.43 million US dollars per year at one poer block with turbine Т-250/300-240.

  7. PLZT capacitor on glass substrate

    Science.gov (United States)

    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.

  8. Radiation effects in polycarbonate capacitors

    Directory of Open Access Journals (Sweden)

    Vujisić Miloš

    2009-01-01

    Full Text Available The aim of this paper is to examine the influence of neutron and gamma irradiation on the dissipation factor and capacitance of capacitors with polycarbonate dielectrics. The operation of capacitors subject to extreme conditions, such as the presence of ionizing radiation fields, is of special concern in military industry and space technology. Results obtained show that the exposure to a mixed neutron and gamma radiation field causes a decrease of capacitance, while the loss tangent remains unchanged.

  9. Electromechanical capacitor for energy transfer

    International Nuclear Information System (INIS)

    Carroll, T.A.; Chowdhuri, P.; Marshall, J.

    1983-01-01

    Inductive energy transfer between two magnets can be achieved with almost 100% efficiency with a transfer capacitor. However, the bulk and cost will be high, and reliability low if conventional capacitors are used. A homopolar machine, used as a capacitor, will be compact and economical. A homopolar machine was designed with counter-rotating copper disks completely immersed in a liquid metal (NaK-78) to work as a pulse capacitor. Absence of solid-brush collectors minimized wear and frictional losses. Wetting of the copper disks throughout the periphery by the liquid metal minimized the resistive losses at the collector interface. A liquid-metal collector would, however, introduce hydrodynamic and magnetohydrodynamic losses. The selected liquid metal, e.g., NaK-78 will produce the lowest of such losses among the available liquid metals. An electromechanical capacitor of this design was tested at various dc magnetic fields. Its measured capacitance was about 100 farads at a dc magnetic field of 1.15 tesla

  10. Thermal Vapor Deposition and Characterization of Polymer-Ceramic Nanoparticle Thin Films and Capacitors

    Science.gov (United States)

    Iwagoshi, Joel A.

    Research on alternative energies has become an area of increased interest due to economic and environmental concerns. Green energy sources, such as ocean, wind, and solar power, are subject to predictable and unpredictable generation intermittencies which cause instability in the electrical grid. This problem could be solved through the use of short term energy storage devices. Capacitors made from composite polymer:nanoparticle thin films have been shown to be an economically viable option. Through thermal vapor deposition, we fabricated dielectric thin films composed of the polymer polyvinylidine fluoride (PVDF) and the ceramic nanoparticle titanium dioxide (TiO2). Fully understanding the deposition process required an investigation of electrode and dielectric film deposition. Film composition can be controlled by the mass ratio of PVDF:TiO2 prior to deposition. An analysis of the relationship between the ratio of PVDF:TiO2 before and after deposition will improve our understanding of this novel deposition method. X-ray photoelectron spectroscopy and energy dispersive x-ray spectroscopy were used to analyze film atomic concentrations. The results indicate a broad distribution of deposited TiO2 concentrations with the highest deposited amount at an initial mass concentration of 17% TiO2. The nanoparticle dispersion throughout the film is analyzed through atomic force microscopy and energy dispersive x-ray spectroscopy. Images from these two techniques confirm uniform TiO2 dispersion with cluster size less than 300 nm. These results, combined with spectroscopic analysis, verify control over the deposition process. Capacitors were fabricated using gold parallel plates with PVDF:TiO 2 dielectrics. These capacitors were analyzed using the atomic force microscope and a capacohmeter. Atomic force microscope images confirm that our gold films are acceptably smooth. Preliminary capacohmeter measurements indicate capacitance values of 6 nF and break down voltages of 2.4 V

  11. Shapeable short circuit resistant capacitor

    Science.gov (United States)

    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.

  12. Structural integrity of ceramic multilayer capacitor materials and ceramic multilayer capacitors

    NARCIS (Netherlands)

    With, de G.

    1993-01-01

    An review with 61 refs. is given of the fracture of and stress situation in ceramic capacitor materials and ceramic multilayer capacitors. A brief introduction to the relevant concepts is given first. Next the data for capacitor materials and the data for capacitors are discussed. The materials data

  13. Super miniaturization of film capacitor dielectrics

    Science.gov (United States)

    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.

  14. Integrated capacitor arrangement for ultrahigh capacitance values

    NARCIS (Netherlands)

    Roozeboom, F.; Klootwijk, J.H.; Kemmeren, A.L.A.M.; Reefman, D.; Verhoeven, J.F.C.M.

    2011-01-01

    An electronic device includes at least one trench capacitor that can also take the form of an inverse structure, a pillar capacitor. An alternating layer sequence of at least two dielectric layers and at least two electrically conductive layers is provided in the trench capacitor or on the pillar

  15. Electrical characterization of thin film ferroelectric capacitors

    NARCIS (Netherlands)

    Tiggelman, M.P.J.; Reimann, K.; Klee, M.; Beelen, D.; Keur, W.; Schmitz, Jurriaan; Hueting, Raymond Josephus Engelbart

    2006-01-01

    Tunable capacitors can be used to facilitate the reduction of components in wireless technologies. The tunability of the capacitors is caused by the sensitivity of the relative dielectric constant to a change in polarization with electric field. Thin film ferroelectric MIM capacitors on silicon

  16. Split-phase motor running as capacitor starts motor and as capacitor run motor

    OpenAIRE

    Yahaya Asizehi ENESI; Jacob TSADO; Mark NWOHU; Usman Abraham USMAN; Odu Ayo IMORU

    2016-01-01

    In this paper, the input parameters of a single phase split-phase induction motor is taken to investigate and to study the output performance characteristics of capacitor start and capacitor run induction motor. The value of these input parameters are used in the design characteristics of capacitor run and capacitor start motor with each motor connected to rated or standard capacitor in series with auxiliary winding or starting winding respectively for the normal operational condition. The ma...

  17. Improved Dielectric Films For Capacitors

    Science.gov (United States)

    Yen, Shiao-Ping S.; Lewis, Carol R.; Cygan, Peter J.; Jow, T. Richard

    1994-01-01

    Dielectric films made from blends of some commercially available high-dielectric-constant cyanoresins with each other and with cellulose triacetate (CTA) have both high dielectric constants and high breakdown strengths. Dielectric constants as high as 16.2. Films used to produce high-energy-density capacitors.

  18. Compositionally Graded Multilayer Ceramic Capacitors.

    Science.gov (United States)

    Song, Hyun-Cheol; Zhou, Jie E; Maurya, Deepam; Yan, Yongke; Wang, Yu U; Priya, Shashank

    2017-09-27

    Multilayer ceramic capacitors (MLCC) are widely used in consumer electronics. Here, we provide a transformative method for achieving high dielectric response and tunability over a wide temperature range through design of compositionally graded multilayer (CGML) architecture. Compositionally graded MLCCs were found to exhibit enhanced dielectric tunability (70%) along with small dielectric losses (filters and power converters.

  19. Nanostructured Electrode Materials for Electrochemical Capacitor Applications.

    Science.gov (United States)

    Choi, Hojin; Yoon, Hyeonseok

    2015-06-02

    The advent of novel organic and inorganic nanomaterials in recent years, particularly nanostructured carbons, conducting polymers, and metal oxides, has enabled the fabrication of various energy devices with enhanced performance. In this paper, we review in detail different nanomaterials used in the fabrication of electrochemical capacitor electrodes and also give a brief overview of electric double-layer capacitors, pseudocapacitors, and hybrid capacitors. From a materials point of view, the latest trends in electrochemical capacitor research are also discussed through extensive analysis of the literature and by highlighting notable research examples (published mostly since 2013). Finally, a perspective on next-generation capacitor technology is also given, including the challenges that lie ahead.

  20. Discharging a DC bus capacitor of an electrical converter system

    Science.gov (United States)

    Kajouke, Lateef A; Perisic, Milun; Ransom, Ray M

    2014-10-14

    A system and method of discharging a bus capacitor of a bidirectional matrix converter of a vehicle are presented here. The method begins by electrically shorting the AC interface of the converter after an AC energy source is disconnected from the AC interface. The method continues by arranging a plurality of switching elements of a second energy conversion module into a discharge configuration to establish an electrical current path from a first terminal of an isolation module, through an inductive element, and to a second terminal of the isolation module. The method also modulates a plurality of switching elements of a first energy conversion module, while maintaining the discharge configuration of the second energy conversion module, to at least partially discharge a DC bus capacitor.

  1. Preparation and Characterization of Cu and Ni on Alumina Supports and Their Use in the Synthesis of Low-Temperature Metal-Phthalocyanine Using a Parallel-Plate Reactor

    Directory of Open Access Journals (Sweden)

    Carlos J. Lucio-Ortiz

    2013-09-01

    Full Text Available Ni- and Cu/alumina powders were prepared and characterized by X-ray diffraction (XRD, scanning electronic microscope (SEM, and N2 physisorption isotherms were also determined. The Ni/Al2O3 sample reveled agglomerated (1 μm of nanoparticles of Ni (30–80 nm however, NiO particles were also identified, probably for the low temperature during the H2 reduction treatment (350 °C, the Cu/Al2O3 sample presented agglomerates (1–1.5 μm of nanoparticles (70–150 nm, but only of pure copper. Both surface morphologies were different, but resulted in mesoporous material, with a higher specificity for the Ni sample. The surfaces were used in a new proposal for producing copper and nickel phthalocyanines using a parallel-plate reactor. Phthalonitrile was used and metallic particles were deposited on alumina in ethanol solution with CH3ONa at low temperatures; ≤60 °C. The mass-transfer was evaluated in reaction testing with a recent three-resistance model. The kinetics were studied with a Langmuir-Hinshelwood model. The activation energy and Thiele modulus revealed a slow surface reaction. The nickel sample was the most active, influenced by the NiO morphology and phthalonitrile adsorption.

  2. Measurement of profile and intensity of proton beam by an integrating current transformer and a segmented parallel-plate ion chamber for the AGS-spallation target experiment (ASTE)

    International Nuclear Information System (INIS)

    Meigo, Shin-ichiro; Nakashima, Hiroshi; Takada, Hiroshi

    2001-03-01

    Profile and intensity of proton beams incident to a mercury target were measured for the experiments under AGS-spallation Target Experiment (ASTE) collaboration. Protons of 1.94, 12 and 24 GeV energy were measured for a temperature, pressure wave and neutronics in the mercury target. For the beam profile measurement, segmented parallel-plate ion chamber (CHIDORI) was used as the online detector. Imaging plates (IP) were also used for the profile measurement with aluminum activation foils as the image converter. An integrating current transformer (ICT) and activation method by Cu foil were used for the measurement of beam intensity. The beam profile obtained by CHIDORI gives a good agreement with the results with the IP. The beam intensity obtained by ICT agrees with the data obtained by the activation technique within ±3% for 12 and 24 GeV cases. Furthermore, these results show in good agreement with those obtained by the monitor of segmented wire ionization chamber (SWIC) and secondary emission chamber (SEC) installed by the AGS team. Therefore, a reliable beam monitor technique was established, so that the analysis of the experiment such as temperature and pressure wave can be normalized by the number of incident protons. (author)

  3. A Two-terminal Active Capacitor

    DEFF Research Database (Denmark)

    Wang, Haoran; Wang, Huai

    2017-01-01

    This letter proposes a concept of two-terminal active capacitor implemented by power semiconductor switches and passive elements. The active capacitor has the same level of convenience as a passive one with two power terminals only. It is application independent and can be specified by rated...... voltage, ripple current, equivalent series resistance, and operational frequency range. The concept, control method, self-power scheme, and impedance characteristics of the active capacitor are presented. A case study of the proposed active capacitor for a capacitive DC-link application is discussed....... The results reveal a significantly lower overall energy storage of passive elements and a reduced cost to fulfill a specific reliability target, compared to a passive capacitor solution. Proof-of-concept experimental results are given to verify the functionality of the proposed capacitor....

  4. Capacitor discharges, magnetohydrodynamics, X-rays, ultrasonics

    CERN Document Server

    Früngel, Frank B A

    1965-01-01

    High Speed Pulse Technology, Volume 1: Capacitor Discharges - Magnetohydrodynamics - X-Rays - Ultrasonics deals with the theoretical and engineering problems that arise in the capacitor discharge technique.This book discusses the characteristics of dielectric material, symmetrical switch tubes with mercury filling, and compensation conductor forms. The transformed discharge for highest current peaks, ignition transformer for internal combustion engines, and X-ray irradiation of subjects in mechanical motion are also elaborated. This text likewise covers the transformed capacitor discharge in w

  5. Evaluation of Polymer Hermetically Sealed Tantalum Capacitors

    Science.gov (United States)

    Teverovsky, Alexander A.

    2014-01-01

    Polymer cathode tantalum capacitors have lower ESR (equivalent series resistance) compared to other types of tantalum capacitors and for this reason have gained popularity in the electronics design community. Their use allows improved performance of power supply systems along with substantial reduction of size and weight of the components used. However, these parts have poor thermal stability and can degrade in humid environments. Polymer hermetically sealed (PHS) capacitors avoid problems related to environmental degradation of molded case parts and can potentially replace current wet and solid hermetically sealed capacitors. In this work, PHS capacitors manufactured per DLA LAM DWG#13030 are evaluated for space applications. Several lots of capacitors manufactured over period from 2010 to 2014 were tested for the consistency of performance, electrical and thermal characteristics, highly accelerated life testing, and robustness under reverse bias and random vibration conditions. Special attention was given to analysis of leakage currents and the effect of long-term high temperature storage on capacitors in as is condition and after hermeticity loss. The results show that PHS capacitors might be especially effective for low-temperature applications or for system requiring a cold start-up. Additional screening and qualification testing have been recommended to assure the necessary quality of capacitors for space projects.

  6. New Temperature-Insensitive Electronically-Tunable Grounded Capacitor Simulator

    OpenAIRE

    Abuelma'atti, Muhammad Taher; Khan, Muhammad Haroon

    1996-01-01

    A new circuit for simulating a grounded capacitor is presented. The circuit uses one operationalamplifier (OA), three operational-transconductance amplifiers (OTAs), and one capacitor. The realized capacitor is temperature-insensitive and electronically tunable. Experimental results are included.

  7. Nanoporous carbon for electrochemical capacitors.

    Energy Technology Data Exchange (ETDEWEB)

    Siegal, Michael P.; Bunker, Bruce Conrad; Limmer, Steven J.; Yelton, William Graham

    2010-05-01

    Nanoporous carbon (NPC) is a purely graphitic material with highly controlled densities ranging from less than 0.1 to 2.0 g/cm3, grown via pulsed-laser deposition. Decreasing the density of NPC increases the interplanar spacing between graphene-sheet fragments. This ability to tune the interplanar spacing makes NPC an ideal model system to study the behavior of carbon electrodes in electrochemical capacitors and batteries. We examine the capacitance of NPC films in alkaline and acidic electrolytes, and measure specific capacitances as high as 242 F/g.

  8. Nanoporous carbon for electrochemical capacitors.

    Energy Technology Data Exchange (ETDEWEB)

    Overmyer, Donald L.; Siegal, Michael P.; Bunker, Bruce Conrad; Limmer, Steven J.; Yelton, William Graham

    2010-04-01

    Nanoporous carbon (NPC) is a purely graphitic material with highly controlled densities ranging from less than 0.1 to 2.0 g/cm3, grown via pulsed-laser deposition. Decreasing the density of NPC increases the interplanar spacing between graphene-sheet fragments. This ability to tune the interplanar spacing makes NPC an ideal model system to study the behavior of carbon electrodes in electrochemical capacitors and batteries. We examine the capacitance of NPC films in alkaline and acidic electrolytes, and measure specific capacitances as high as 242 F/g.

  9. Capacitor ageing in electronic devices

    Directory of Open Access Journals (Sweden)

    Richard B. N. Vital

    2015-10-01

    Full Text Available The moment when an electronic component doesn’t work like requirements, previously established is a task that need to be considered since began of a system design. However, the use of different technologies, operating under several environmental conditions, makes a component choice a complex step in system design. This paper analyzes the effects that ageing phenomenon of capacitors may introduce in electronic devices operation. For this reason, reliability concepts, processes and mechanism of degradation are presented. Additionally, some mathematical models are presented to assist maintenance activities or component replacement. The presented approach compares the operability of intact and aged components.

  10. Simple Ways to Make Real Capacitors

    Science.gov (United States)

    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. Dielectric material options for integrated capacitors

    NARCIS (Netherlands)

    Ruhl, G.; Lehnert, W.; Lukosius, M.; Wenger, C.; Baristiran Kaynak, C.; Blomberg, T.; Haukka, S.; Baumann, P.K.; Besling, W.F.A.; Roest, A.L.; Riou, B.; Lhostis, S.; Halimaou, A.; Roozeboom, F.; Langereis, E.; Kessels, W.M.M.; Zauner, A.; Rushworth, S.A.

    2014-01-01

    Future MIM capacitor generations will require significantly increased specific capacitances by utilization of high-k dielectric materials. In order to achieve high capacitance per chip area, these dielectrics have to be deposited in three-dimensional capacitor structures by ALD or AVD (atomic vapor

  12. Cellulose Triacetate Dielectric Films For Capacitors

    Science.gov (United States)

    Yen, Shiao-Ping S.; Jow, T. Richard

    1994-01-01

    Cellulose triacetate investigated for use as dielectric material in high-energy-density capacitors for pulsed-electrical-power systems. Films of cellulose triacetate metalized on one or both sides for use as substrates for electrodes and/or as dielectrics between electrodes in capacitors. Used without metalization as simple dielectric films. Advantages include high breakdown strength and self-healing capability.

  13. Microprocessor Controlled Capacitor Bank Switching System for ...

    African Journals Online (AJOL)

    In this work, analysis and development of a microprocessor controlled capacitor bank switching system for deployment in a smart distribution network was carried out. This system was implemented by the use of discreet components such as resistors, capacitors, transistor, diode, automatic voltage regulator, with the ...

  14. Surface Aggregation of Candida albicans on Glass in the Absence and Presence of Adhering Streptococcus gordonii in a Parallel-Plate Flow Chamber: A Surface Thermodynamical Analysis Based on Acid-Base Interactions.

    Science.gov (United States)

    Millsap; Bos; Busscher; van der Mei HC

    1999-04-15

    Adhesive interactions between yeasts and bacteria are important in the maintenance of infectious mixed biofilms on natural and biomaterial surfaces in the human body. In this study, the extended DLVO (Derjaguin-Landau-Verwey-Overbeek) approach has been applied to explain adhesive interactions between C. albicans ATCC 10261 and S. gordonii NCTC 7869 adhering on glass. Contact angles with different liquids and the zeta potentials of both the yeasts and bacteria were determined and their adhesive interactions were measured in a parallel-plate flow chamber.Streptococci were first allowed to adhere to the bottom glass plate of the flow chamber to different seeding densities, and subsequently deposition of yeasts was monitored with an image analysis system, yielding the degree of initial surface aggregation of the adhering yeasts and their spatial arrangement in a stationary end point. Irrespective of growth temperature, the yeast cells appeared uncharged in TNMC buffer, but yeasts grown at 37 degrees C were intrinsically more hydrophilic and had an increased electron-donating character than cells grown at 30 degrees C. All yeasts showed surface aggregation due to attractive Lifshitz-van der Waals forces. In addition, acid-base interactions between yeasts, yeasts and the glass substratum, and yeasts and the streptococci were attractive for yeasts grown at 30 degrees C, but yeasts grown at 37 degrees C only had favorable acid-base interactions with the bacteria, explaining the positive relationship between the surface coverage of the glass by streptococci and the surface aggregation of the yeasts. Copyright 1999 Academic Press.

  15. Nanostructured Electrode Materials for Electrochemical Capacitor Applications

    Directory of Open Access Journals (Sweden)

    Hojin Choi

    2015-06-01

    Full Text Available The advent of novel organic and inorganic nanomaterials in recent years, particularly nanostructured carbons, conducting polymers, and metal oxides, has enabled the fabrication of various energy devices with enhanced performance. In this paper, we review in detail different nanomaterials used in the fabrication of electrochemical capacitor electrodes and also give a brief overview of electric double-layer capacitors, pseudocapacitors, and hybrid capacitors. From a materials point of view, the latest trends in electrochemical capacitor research are also discussed through extensive analysis of the literature and by highlighting notable research examples (published mostly since 2013. Finally, a perspective on next-generation capacitor technology is also given, including the challenges that lie ahead.

  16. Switched-capacitor isolated LED driver

    Science.gov (United States)

    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.

  17. Electric field mapping inside metallized film capacitors

    DEFF Research Database (Denmark)

    Nielsen, Dennis Achton; Popok, Vladimir; Pedersen, Kjeld

    2015-01-01

    (s) they suffered from accelerated testing. We have prepared film capacitors for analysis by micro-sectioning and verified the quality of the preparation procedure using optical and atomic force microscopy. The potential distribution in the layer structure (alternating 7 µm thick dielectric and 50-100 nm thick...... and durability and serves as verification that failure- and degradation mechanisms remain the same at different stress levels during accelerated testing. In this work we have used Kelvin probe force microscopy (KPFM) to analyze metallized film capacitors with the purpose of determining the degradation mechanism...... metal) of a new capacitor was used as reference. KPFM measurements on the degraded capacitors showed a change in contact potential difference from -0.61V on the reference capacitor to 3.2V on the degraded ones, indicating that corrosion of the metallization had happened. Studies also showed that some...

  18. Memory characteristics of an MOS capacitor structure with double-layer semiconductor and metal heterogeneous nanocrystals

    International Nuclear Information System (INIS)

    Ni Henan; Wu Liangcai; Song Zhitang; Hui Chun

    2009-01-01

    An MOS (metal oxide semiconductor) capacitor structure with double-layer heterogeneous nanocrystals consisting of semiconductor and metal embedded in a gate oxide for nonvolatile memory applications has been fabricated and characterized. By combining vacuum electron-beam co-evaporated Si nanocrystals and self-assembled Ni nanocrystals in a SiO 2 matrix, an MOS capacitor with double-layer heterogeneous nanocrystals can have larger charge storage capacity and improved retention characteristics compared to one with single-layer nanocrystals. The upper metal nanocrystals as an additional charge trap layer enable the direct tunneling mechanism to enhance the flat voltage shift and prolong the retention time. (semiconductor devices)

  19. 2014 NEPP Tasks Update for Ceramic and Tantalum Capacitors

    Science.gov (United States)

    Teverovsky, Alexander A.

    2014-01-01

    Presentation describes recent development in research on MnO2, wet, and polymer tantalum capacitors. Low-voltage failures in multilayer ceramic capacitors and techniques to reveal precious metal electrode (PME) and base metal electrode (BME) capacitors with cracks are discussed. A voltage breakdown technique is suggested to select high quality low-voltage BME ceramic capacitors.

  20. Charge Fluctuations in Nanoscale Capacitors

    Science.gov (United States)

    Limmer, David T.; Merlet, Céline; Salanne, Mathieu; Chandler, David; Madden, Paul A.; van Roij, René; Rotenberg, Benjamin

    2013-09-01

    The fluctuations of the charge on an electrode contain information on the microscopic correlations within the adjacent fluid and their effect on the electronic properties of the interface. We investigate these fluctuations using molecular dynamics simulations in a constant-potential ensemble with histogram reweighting techniques. This approach offers, in particular, an efficient, accurate, and physically insightful route to the differential capacitance that is broadly applicable. We demonstrate these methods with three different capacitors: pure water between platinum electrodes and a pure as well as a solvent-based organic electrolyte each between graphite electrodes. The total charge distributions with the pure solvent and solvent-based electrolytes are remarkably Gaussian, while in the pure ionic liquid the total charge distribution displays distinct non-Gaussian features, suggesting significant potential-driven changes in the organization of the interfacial fluid.

  1. Charge fluctuations in nanoscale capacitors.

    Science.gov (United States)

    Limmer, David T; Merlet, Céline; Salanne, Mathieu; Chandler, David; Madden, Paul A; van Roij, René; Rotenberg, Benjamin

    2013-09-06

    The fluctuations of the charge on an electrode contain information on the microscopic correlations within the adjacent fluid and their effect on the electronic properties of the interface. We investigate these fluctuations using molecular dynamics simulations in a constant-potential ensemble with histogram reweighting techniques. This approach offers, in particular, an efficient, accurate, and physically insightful route to the differential capacitance that is broadly applicable. We demonstrate these methods with three different capacitors: pure water between platinum electrodes and a pure as well as a solvent-based organic electrolyte each between graphite electrodes. The total charge distributions with the pure solvent and solvent-based electrolytes are remarkably Gaussian, while in the pure ionic liquid the total charge distribution displays distinct non-Gaussian features, suggesting significant potential-driven changes in the organization of the interfacial fluid.

  2. Harmonic Resonance in Power Transmission Systems due to the Addition of Shunt Capacitors

    Science.gov (United States)

    Patil, Hardik U.

    Shunt capacitors are often added in transmission networks at suitable locations to improve the voltage profile. In this thesis, the transmission system in Arizona is considered as a test bed. Many shunt capacitors already exist in the Arizona transmission system and more are planned to be added. Addition of these shunt capacitors may create resonance conditions in response to harmonic voltages and currents. Such resonance, if it occurs, may create problematic issues in the system. It is main objective of this thesis to identify potential problematic effects that could occur after placing new shunt capacitors at selected buses in the Arizona network. Part of the objective is to create a systematic plan for avoidance of resonance issues. For this study, a method of capacitance scan is proposed. The bus admittance matrix is used as a model of the networked transmission system. The calculations on the admittance matrix were done using Matlab. The test bed is the actual transmission system in Arizona; however, for proprietary reasons, bus names are masked in the thesis copy intended for the public domain. The admittance matrix was obtained from data using the PowerWorld Simulator after equivalencing the 2016 summer peak load (planning case). The full Western Electricity Coordinating Council (WECC) system data were used. The equivalencing procedure retains only the Arizona portion of the WECC. The capacitor scan results for single capacitor placement and multiple capacitor placement cases are presented. Problematic cases are identified in the form of 'forbidden response. The harmonic voltage impact of known sources of harmonics, mainly large scale HVDC sources, is also presented. Specific key results for the study indicated include: (1) The forbidden zones obtained as per the IEEE 519 standard indicates the bus 10 to be the most problematic bus. (2) The forbidden zones also indicate that switching values for the switched shunt capacitor (if used) at bus 3 should be

  3. Nanocomposite multilayer capacitors comprising BaTiO3@TiO2 and poly(vinylidene fluoride-hexafluoropropylene for dielectric-based energy storage

    Directory of Open Access Journals (Sweden)

    Mojtaba Rahimabady

    2014-04-01

    Full Text Available Multilayer dielectric capacitors were fabricated from nanocomposite precursor comprised of BaTiO3@TiO2 core–shell nanosized particles and poly(vinylidene fluoride–hexafluoropropylene (P(VDF–HFP polymer matrix (20 vol%. The multilayer capacitors showed very high discharge speed and high discharged energy density of around 2.5 J/cm3 at its breakdown field (~ 166 MV/m. The energy density of the nanocomposite multilayer capacitors was substantially higher than the energy density of commercially used power capacitors. Low cost, flexible structure, high discharge rate and energy density suggest that the nanocomposite multilayer capacitors are promising for energy storage applications in many power devices and systems.

  4. Physical and Electrical Characterization of Polymer Aluminum Capacitors

    Science.gov (United States)

    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.

  5. Physical and Electrical Characterization of Aluminum Polymer Capacitors

    Science.gov (United States)

    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.

  6. Capacitor Voltages Measurement and Balancing in Flying Capacitor Multilevel Converters Utilizing a Single Voltage Sensor

    DEFF Research Database (Denmark)

    Farivar, Glen; Ghias, Amer M. Y. M.; Hredzak, Branislav

    2017-01-01

    This paper proposes a new method for measuring capacitor voltages in multilevel flying capacitor (FC) converters that requires only one voltage sensor per phase leg. Multiple dc voltage sensors traditionally used to measure the capacitor voltages are replaced with a single voltage sensor at the ac...... side of the phase leg. The proposed method is subsequently used to balance the capacitor voltages using only the measured ac voltage. The operation of the proposed measurement and balancing method is independent of the number of the converter levels. Experimental results presented for a five-level FC...

  7. High Energy Density Capacitors, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — Capacitor size and reliability are often limiting factors in pulse power, high speed switching, and power management and distribution (PMAD) systems. T/J...

  8. High Energy Density Polymer Film Capacitors

    National Research Council Canada - National Science Library

    Boufelfel, Ali

    2006-01-01

    High-energy-density capacitors that are compact and light-weight are extremely valuable in a number of critical DoD systems that include portable field equipment, pulsed lasers, detection equipment...

  9. Single ICCII Sinusoidal Oscillators Employing Grounded Capacitors

    Directory of Open Access Journals (Sweden)

    J. W. Horng

    2011-09-01

    Full Text Available Two inverting second-generation current conveyors (ICCII based sinusoidal oscillators are presented. The first sinusoidal oscillator is composed of one ICCII, two grounded capacitors and two resistors. The oscillation condition and oscillation frequency can be orthogonally controllable. The second sinusoidal oscillator is composed of one ICCII, two grounded capacitors and three resistors. The oscillation condition and oscillation frequency can be independently controllable through different resistors.

  10. Cellulose triacetate, thin film dielectric capacitor

    Science.gov (United States)

    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.

  11. Transmission Line Resonator Segmented with Series Capacitors

    DEFF Research Database (Denmark)

    Zhurbenko, Vitaliy; Boer, Vincent; Petersen, Esben Thade

    2016-01-01

    Transmission line resonators are often used as coils in high field MRI. Due to distributed nature of such resonators, coils based on them produce inhomogeneous field. This work investigates application of series capacitors to improve field homogeneity along the resonator. The equations for optimal...... values of evenly distributed capacitors are presented. The performances of the segmented resonator and a regular transmission line resonator are compared....

  12. Capacitor blocks for linear transformer driver stages.

    Science.gov (United States)

    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.

  13. Protection of MOS capacitors during anodic bonding

    Science.gov (United States)

    Schjølberg-Henriksen, K.; Plaza, J. A.; Rafí, J. M.; Esteve, J.; Campabadal, F.; Santander, J.; Jensen, G. U.; Hanneborg, A.

    2002-07-01

    We have investigated the electrical damage by anodic bonding on CMOS-quality gate oxide and methods to prevent this damage. n-type and p-type MOS capacitors were characterized by quasi-static and high-frequency CV-curves before and after anodic bonding. Capacitors that were bonded to a Pyrex wafer with 10 μm deep cavities enclosing the capacitors exhibited increased leakage current and interface trap density after bonding. Two different methods were successful in protecting the capacitors from such damage. Our first approach was to increase the cavity depth from 10 μm to 50 μm, thus reducing the electric field across the gate oxide during bonding from approximately 2 × 105 V cm-1 to 4 × 104 V cm-1. The second protection method was to coat the inside of a 10 μm deep Pyrex glass cavity with aluminium, forming a Faraday cage that removed the electric field across the cavity during anodic bonding. Both methods resulted in capacitors with decreased interface trap density and unchanged leakage current after bonding. No change in effective oxide charge or mobile ion contamination was observed on any of the capacitors in the study.

  14. Physics of failure based analysis of aluminium electrolytic capacitor

    International Nuclear Information System (INIS)

    Sahoo, Satya Ranjan; Behera, S.K.; Kumar, Sachin; Varde, P.V.; Ravi Kumar, G.

    2016-01-01

    Electrolytic capacitors are one of the important devices in various power electronic systems, such as motor drives, uninterruptible power supply, electric vehicles and dc power supply. Electrolytic capacitors are also the integral part of many other electronic devices. One of the primary function of electrolytic capacitors is the smoothing of voltage ripple and storing electrical energy. However, the electrolytic capacitor has the shortest lifespan of components in power electronics. Past experiences show that electrolytic capacitor tends to degrade and fail faster under high electrical or thermal stress conditions during operations. The primary failure mechanism of an electrolytic capacitor is the evaporation of the electrolyte due to electrical or thermal overstress. This leads to the drift in the values of two important parameters-capacitance and equivalent series resistance (ESR) of the electrolytic capacitor. An attempt has been made to age the electrolytic capacitor and validate the results. The overall goal is to derive the accurate degradation model of the electrolytic capacitor. (author)

  15. Method of manufacturing a capacitor on a nanowire and integrated circuit having such a capacitor

    NARCIS (Netherlands)

    2009-01-01

    A method of manufacturing a capacitor on a wafer, and an IC comprising such a capacitor is disclosed. The method comprises forming a plurality of vertical structures (140) each having a sub-micron thickness on the wafer; and growing a metal-insulator-metal (MIM) stack (150) over the plurality of

  16. Microscale electrostatic fractional capacitors using reduced graphene oxide percolated polymer composites

    KAUST Repository

    Elshurafa, Amro M.

    2013-06-14

    We show that graphene-percolated polymer composites exhibit fractional capacitance response in the frequency range of 50 kHz–2 MHz. In addition, it is shown that by varying the loading of graphene within the matrix from 2.5% to 12%, the phase can be controllably tuned from −67° to −31°, respectively. The electrostatic fractional capacitors proposed herein are easy to fabricate and offer integration capability on electronic printed circuit boards.

  17. Energy Efficient Graphene Based High Performance Capacitors.

    Science.gov (United States)

    Bae, Joonwon; Kwon, Oh Seok; Lee, Chang-Soo

    2017-07-10

    Graphene (GRP) is an interesting class of nano-structured electronic materials for various cutting-edge applications. To date, extensive research activities have been performed on the investigation of diverse properties of GRP. The incorporation of this elegant material can be very lucrative in terms of practical applications in energy storage/conversion systems. Among various those systems, high performance electrochemical capacitors (ECs) have become popular due to the recent need for energy efficient and portable devices. Therefore, in this article, the application of GRP for capacitors is described succinctly. In particular, a concise summary on the previous research activities regarding GRP based capacitors is also covered extensively. It was revealed that a lot of secondary materials such as polymers and metal oxides have been introduced to improve the performance. Also, diverse devices have been combined with capacitors for better use. More importantly, recent patents related to the preparation and application of GRP based capacitors are also introduced briefly. This article can provide essential information for future study. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  18. Downhole transmission system comprising a coaxial capacitor

    Science.gov (United States)

    Hall, David R [Provo, UT; Pixton, David S [Lehi, UT; Johnson, Monte L [Orem, UT; Bartholomew, David B [Springville, UT; Hall, Jr., H. Tracy; Rawle, Michael [Springville, UT

    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.

  19. Pseudo-capacitor device for aqueous electrolytes

    Science.gov (United States)

    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.

  20. Negative capacitance in a ferroelectric capacitor.

    Science.gov (United States)

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

    2015-02-01

    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 a phase transition, could provide a solution, but a direct measurement of negative capacitance has so far been elusive. Here, we report the observation of negative capacitance in a thin, epitaxial ferroelectric film. 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. Analysis of this 'inductance'-like behaviour from a capacitor presents an unprecedented insight into the intrinsic energy profile of the ferroelectric material and could pave the way for completely new applications.

  1. Improving the mechanical stability of a standard capacitor

    CSIR Research Space (South Africa)

    Moodley, SS

    2003-04-01

    Full Text Available temperature coefficients of capacitance, they were susceptible to mechanical shock. During 1999, a project was initiated to improve the mechanical stability of the capacitors after two capacitors were damaged during transit, while being transported as separate...

  2. Li-Ion, Ultra-capacitor Based Hybrid Energy Module

    National Research Council Canada - National Science Library

    Daboussi, Zaher; Paryani, Anil; Khalil, Gus; Catherino, Henry; Gargies, Sonya

    2007-01-01

    .... To determine the optimum utilization of ultra-capacitors in applications where high power density and high energy density are required, an optimized Li-Ion/Ultra-capacitor Hybrid Energy Module (HEM...

  3. Liquid Crystals of Lithium Dodecylbenzenesulfonate for Electric Double Layer Capacitors

    International Nuclear Information System (INIS)

    Kuzmin, Andrey Vasil’evich; Yurtov, Evgeny V.

    2016-01-01

    Ionic lyotropic liquid crystals based on lithium dodecylbenzenesulfonate were used as electrolytes for electric double layer capacitors with carbon fibrous electrodes. The capacitors were tasted by cyclic voltammetry, galvanostatic charge and discharge, and impedance spectroscopy. The highest specific capacitance was achieved for electrical double layer capacitor equipped with ionic lyotropic liquid crystal of lithium dodecylbenzenesulfonate 35 wt% in water. The specific capacitance of capacitor was calculated from galvanostatic discharge curves – 15 F/g of carbon fibrous material

  4. Method of making dielectric capacitors with increased dielectric breakdown strength

    Science.gov (United States)

    Ma, Beihai; Balachandran, Uthamalingam; Liu, Shanshan

    2017-05-09

    The invention is directed to a process for making a dielectric ceramic film capacitor and the ceramic dielectric laminated capacitor formed therefrom, the dielectric ceramic film capacitors having increased dielectric breakdown strength. The invention increases breakdown strength by embedding a conductive oxide layer between electrode layers within the dielectric layer of the capacitors. The conductive oxide layer redistributes and dissipates charge, thus mitigating charge concentration and micro fractures formed within the dielectric by electric fields.

  5. Design and Characterization of Vertical Mesh Capacitors in Standard CMOS

    DEFF Research Database (Denmark)

    Christensen, Kåre Tais

    2001-01-01

    This paper shows how good RF capacitors can be made in a standard digital CMOS process. The capacitors which are also well suited for binary weighted switched capacitor banks show very good RF performance: Q-values of 57 at 4.0 GHz, a density of 0.27 fF/μ2, 2.2 μm wide shielded unit capacitors, 6...

  6. Performance of ALVAND 1. capacitor bank

    International Nuclear Information System (INIS)

    Torabi-fard, A.; Farahani, M.; Ebrani, M.; Rostami, R.; Daghighian, F.

    1978-01-01

    This report describes the specifications of the capacitor bank for the ALVAND I, Linear theta pinch experiment and the results of some tests performed on it. A one-meter-wide module includes the basic components such as capacitors, Spark gaps, and crowbar triggers. Complementary parts such as ground system, pressurised dry air system and safety system were added. With a rise-time of about three micro-seconds and a total current of six million amperes it is possible to produce ion temperature in excess of one kev for a few microseconds. Different probes were used to measure the magnetic field and the total current

  7. Printed Barium Strontium Titanate capacitors on silicon

    Energy Technology Data Exchange (ETDEWEB)

    Sette, Daniele [Univ. Grenoble Alpes, F-38000 Grenoble (France); CEA, LETI, MINATEC Campus, F-38054 Grenoble (France); Luxembourg Institute of Science and Technology LIST, Materials Research and Technology Department, L-4422 Belvaux (Luxembourg); Kovacova, Veronika [Univ. Grenoble Alpes, F-38000 Grenoble (France); CEA, LETI, MINATEC Campus, F-38054 Grenoble (France); Defay, Emmanuel, E-mail: emmanuel.defay@list.lu [Univ. Grenoble Alpes, F-38000 Grenoble (France); CEA, LETI, MINATEC Campus, F-38054 Grenoble (France); Luxembourg Institute of Science and Technology LIST, Materials Research and Technology Department, L-4422 Belvaux (Luxembourg)

    2015-08-31

    In this paper, we show that Barium Strontium Titanate (BST) films can be prepared by inkjet printing of sol–gel precursors on platinized silicon substrate. Moreover, a functional variable capacitor working in the GHz range has been made without any lithography or etching steps. Finally, this technology requires 40 times less precursors than the standard sol–gel spin-coating technique. - Highlights: • Inkjet printing of Barium Strontium Titanate films • Deposition on silicon substrate • Inkjet printed silver top electrode • First ever BST films thinner than 1 μm RF functional variable capacitor that has required no lithography.

  8. Graphene spin capacitor for magnetic field sensing

    OpenAIRE

    Semenov, Y. G.; Zavada, J. M.; Kim, K. W.

    2010-01-01

    An analysis of a novel magnetic field sensor based on a graphene spin capacitor is presented. The proposed device consists of graphene nanoribbons on top of an insulator material connected to a ferromagnetic source/drain. The time evolution of spin polarized electrons injected into the capacitor can be used for an accurate determination at room temperature of external magnetic fields. Assuming a spin relaxation time of 100 ns, magnetic fields on the order of $\\sim 10$ mOe may be detected at r...

  9. Antenna Miniaturization with MEMS Tunable Capacitors

    DEFF Research Database (Denmark)

    Barrio, Samantha Caporal Del; Morris, Art; Pedersen, Gert Frølund

    2014-01-01

    In today’s mobile device market, there is a strong need for efficient antenna miniaturization. Tunable antennas are a very promising way to reduce antenna volume while enlarging its operating bandwidth. MEMS tunable capacitors are state-ofthe- art in terms of insertion loss and their characterist......In today’s mobile device market, there is a strong need for efficient antenna miniaturization. Tunable antennas are a very promising way to reduce antenna volume while enlarging its operating bandwidth. MEMS tunable capacitors are state-ofthe- art in terms of insertion loss...

  10. Low-Voltage Switched-Capacitor Circuits

    DEFF Research Database (Denmark)

    Bidari, E.; Keskin, M.; Maloberti, F.

    1999-01-01

    Switched-capacitor stages are described which can function with very low (typically 1 V) supply voltages, without using voltage boosting or switched op-amps. Simulations indicate that high performance may be achieved using these circuits in filter or data converter applications.......Switched-capacitor stages are described which can function with very low (typically 1 V) supply voltages, without using voltage boosting or switched op-amps. Simulations indicate that high performance may be achieved using these circuits in filter or data converter applications....

  11. Clocking Scheme for Switched-Capacitor Circuits

    DEFF Research Database (Denmark)

    Steensgaard-Madsen, Jesper

    1998-01-01

    A novel clocking scheme for switched-capacitor (SC) circuits is presented. It can enhance the understanding of SC circuits and the errors caused by MOSFET (MOS) switches. Charge errors, and techniques to make SC circuits less sensitive to them are discussed.......A novel clocking scheme for switched-capacitor (SC) circuits is presented. It can enhance the understanding of SC circuits and the errors caused by MOSFET (MOS) switches. Charge errors, and techniques to make SC circuits less sensitive to them are discussed....

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

    International Nuclear Information System (INIS)

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

    2016-01-01

    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.

  13. Application of PFN capacitors in high power systems

    International Nuclear Information System (INIS)

    Parker, R.D.

    1979-01-01

    The application of lightweight reliable capacitors in a mobile energy store is discussed. The relationship of system design parameters to capacitor size and life is displayed. Electric fields and weights of a 21 J/lb and a 77 J/lb pulse discharge capacitor design are given. Estimates of future near-tern development are made

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

    Science.gov (United States)

    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…

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

    Energy Technology Data Exchange (ETDEWEB)

    Taniguchi, Y.; Ishii, Y.; Al-zubaidi, A.; Kawasaki, S., E-mail: kawasaki.shinji@nitech.ac.jp [Nagoya Institute of Technology, Gokiso, Showa, Nagoya, Aichi (Japan); Rashid, M.; Syakirin, A. [Universiti Teknologi MARA (UiTM), 40450 Shah Alam, Selangor (Malaysia)

    2016-07-06

    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.

  16. Capacitors and Resistance-Capacitance Networks.

    Science.gov (United States)

    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)

  17. Charge and Energy Stored in a Capacitor

    Science.gov (United States)

    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.)

  18. Charging a Capacitor with a Photovoltaic Module

    Science.gov (United States)

    Aguilar, Horacio Munguía; Maldonado, Rigoberto Franco; Navarro, Luis Barba

    2017-01-01

    Charging a capacitor with a photovoltaic module is an experiment which reveals a lot about the modules characteristics. It is customary to represent these characteristics with an equivalent circuit whose elements represent its physical parameters. The behavior of a photovoltaic module is very similar to that of a single cell but the electric…

  19. Effects of Radiation on Capacitor Dielectrics

    Science.gov (United States)

    Bouquet, F. L.; Somoano, R. B.; Frickland, P. O.

    1987-01-01

    Data gathered on key design parameters. Report discusses study of electrical and mechanical properties of irradiated polymer dielectric materials. Data compiled for use by designers of high-energy-density capacitors that operate in presence of ionizing radiation. Study focused on polycarbonates, polyetheretherketones, polymethylpentenes, polyimides (including polyetherimide), polyolefins, polysulfones (including polyethersulfone and polyphenylsulfone), and polyvinylidene fluorides.

  20. Capacitor discharge process for welding braided cable

    Science.gov (United States)

    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.

  1. Capacitor Monitoring for Modular Multilevel Converters

    DEFF Research Database (Denmark)

    Deng, Fujin; Liu, Dong; Wang, Yanbo

    2017-01-01

    ). The capacitor monitoring in each SM of the MMC is an important issue, which would affect the performance of the MMC. This paper proposed an effective monitoring method for the capacitance in each SM of the MMC. The proposed method reveals the relationship between the arm average capacitance and the capacitance...

  2. Humidity Testing of PME and BME Ceramic Capacitors with Cracks

    Science.gov (United States)

    Teverovsky, Alexander A.; Herzberger, Jaemi

    2014-01-01

    Cracks in ceramic capacitors are one of the major causes of failures during operation of electronic systems. Humidity testing has been successfully used for many years to verify the absence of cracks and assure quality of military grade capacitors. Traditionally, only precious metal electrode (PME) capacitors were used in high reliability applications and the existing requirements for humidity testing were developed for this type of parts. With the advance of base metal electrode (BME) capacitors, there is a need for assessment of the applicability of the existing techniques for the new technology capacitors. In this work, variety of different PME and BME capacitors with introduced cracks were tested in humid environments at different voltages and temperatures. Analysis of the test results indicates differences in the behavior and failure mechanisms for BME and PME capacitors and the need for different testing conditions.

  3. Reliability Evaluation of Power Capacitors in a Wind Turbine System

    DEFF Research Database (Denmark)

    Zhou, Dao; Blaabjerg, Frede

    2018-01-01

    With the increasing penetration of wind power, reliable and cost-effective wind energy production is of more and more importance. The doubly-fed induction generator based partial-scale wind power converter is still dominating in the existing wind farms. In this paper, the reliability assessment...... block diagram is used to bridge the gap between the Weibull distribution based component-level individual capacitor and the capacitor bank. A case study of a 2 MW wind power converter shows that the lifetime is significantly reduced from the individual capacitor to the capacitor bank. Besides, the dc...... of power capacitors is studied considering the annual mission profile. According to an electro-thermal stress evaluation, the time-to-failure distribution of both the dc-link capacitor and ac-side filter capacitor is detailed investigated. Aiming for the systemlevel reliability analysis, a reliability...

  4. Capacitor performance limitations in high power converter applications

    DEFF Research Database (Denmark)

    El-Khatib, Walid Ziad; Holbøll, Joachim; Rasmussen, Tonny Wederberg

    2013-01-01

    High voltage low inductance capacitors are used in converters as HVDC-links, snubber circuits and sub model (MMC) capacitances. They facilitate the possibility of large peak currents under high frequent or transient voltage applications. On the other hand, using capacitors with larger equivalent...... series inductances include the risk of transient overvoltages, with a negative effect on life time and reliability of the capacitors. These allowable limits of such current and voltage peaks are decided by the ability of the converter components, including the capacitors, to withstand them over...... the expected life time. In this paper results are described from investigations on the electrical environment of these capacitors, including all the conditions they would be exposed to, thereby trying to find the tradeoffs needed to find a suitable capacitor. Different types of capacitors with the same voltage...

  5. Faraday Rotator 5 kV Capacitor Bank

    International Nuclear Information System (INIS)

    Fetterman, C.C.

    1975-01-01

    A Faraday rotator 5 kV capacitor bank is a pulsed output power supply used to energize Faraday rotators for optical isolation in the ''LLL kJ Glass Laser System.'' Each supply contains either one, two or three parallel 240 μF storage capacitors depending on the size of the isolator used. Generally, the ''A*''(216 μH) isolator is energized with one capacitor, the ''A''(116 μH) isolator uses two capacitors and the ''B''(87 μH) isolator requires three capacitors. All models of isolators have been tested with four capacitors under maximum voltage and 25 feet of RG-217 cable with no hazardous effects. Except for the number of capacitors in each unit, the supplies are otherwise physically identical

  6. Thermally tunable VO2-SiO2 nanocomposite thin-film capacitors

    Science.gov (United States)

    Sun, Yifei; Narayanachari, K. V. L. V.; Wan, Chenghao; Sun, Xing; Wang, Haiyan; Cooley, Kayla A.; Mohney, Suzanne E.; White, Doug; Duwel, Amy; Kats, Mikhail A.; Ramanathan, Shriram

    2018-03-01

    We present a study of co-sputtered VO2-SiO2 nanocomposite dielectric thin-film media possessing continuous temperature tunability of the dielectric constant. The smooth thermal tunability is a result of the insulator-metal transition in the VO2 inclusions dispersed within an insulating matrix. We present a detailed comparison of the dielectric characteristics of this nanocomposite with those of a VO2 control layer and of VO2/SiO2 laminate multilayers of comparable overall thickness. We demonstrated a nanocomposite capacitor that has a thermal capacitance tunability of ˜60% between 25 °C and 100 °C at 1 MHz, with low leakage current. Such thermally tunable capacitors could find potential use in applications such as sensing, thermal cloaks, and phase-change energy storage devices.

  7. Multilayer ceramic capacitors for pulsed power, high temperature applications

    International Nuclear Information System (INIS)

    Cygan, S.; McLarney, J.; Prymak, J.; Bohn, P.

    1991-01-01

    The performance of the multilayer ceramic capacitors (MLC) in high frequency power applications has improved significantly over the last years. One of the possible applications of MLC capacitors is the automotive industry where repetitive discharging of capacitors is required. A 0.25-μF capacitor using NPO dielectric subjected to repetitive discharging with the rate of 700 pulses per second, magnitude of 600-V and 195-A peak currents showed no degradation in performance at 298 K or 398 K even after 1 billion discharge cycles. Less than a 5-K temperature rise was observed under these conditions. The most exciting, newly emerging utilization for MLC capacitors, however, might be the high temperature application (up to 473 K for underhood utilization), where ceramic capacitors with higher volumetric efficiency as compared to glass or polymer type capacitors prove very superior. Moreover ceramic capacitors, which next to glass capacitors exhibit the greatest radiation resistance among all insulating materials (Hanks and Hamman 1971), might also be best suited in the future for high temperature operation in space environment. The pulsed power performance of the 0.25-μF NPO capacitor was evaluated under repetitive discharge conditions (200 V, 700 pps) at high temperature, 473 K, and the results are presented in this paper

  8. Diagnostics and performance evaluation of multikilohertz capacitors

    International Nuclear Information System (INIS)

    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

  9. Super dielectric capacitor using scaffold dielectric

    OpenAIRE

    Phillips, Jonathan

    2018-01-01

    Patent A capacitor having first and second electrodes and a scaffold dielectric. The scaffold dielectric comprises an insulating material with a plurality of longitudinal channels extending across the dielectric and filled with a liquid comprising cations and anions. The plurality of longitudinal channels are substantially parallel and the liquid within the longitudinal channels generally has an ionic strength of at least 0.1. Capacitance results from the migrations of...

  10. Capacitor requirements for controlled thermonuclear experiments and reactors

    International Nuclear Information System (INIS)

    Boicourt, G.P.; Hoffman, P.S.

    1975-01-01

    Future controlled thermonuclear experiments as well as controlled thermonuclear reactors will require substantial numbers of capacitors. The demands on these units are likely to be quite severe and quite different from the normal demands placed on either present energy storage capacitors or present power factor correction capacitors. It is unlikely that these two types will suffice for all necessary Controlled Thermonuclear Research (CTR) applications. The types of capacitors required for the various CTR operating conditions are enumerated. Factors that influence the life, cost and operating abilities of these types of capacitors are discussed. The problems of capacitors in a radiation environment are considered. Areas are defined where future research is needed. Some directions that this research should take are suggested. (U.S.)

  11. Capacitor requirements for controlled thermonuclear experiments and reactors

    International Nuclear Information System (INIS)

    Boicourt, G.P.; Hoffman, P.S.

    1975-01-01

    Future controlled thermonuclear experiments as well as controlled thermonuclear reactors will require substantial numbers of capacitors. The demands on these units are likely to be quite severe and quite different from the normal demands placed on either present energy storage capacitors or present power factor correction capacitors. It is unlikely that these two types will suffice for all necessary Controlled Thermonuclear Research (CTR) applications. The types of capacitors required for the various CTR operating conditions are enumerated. Factors that influence the life, cost and operating abilities of these types of capacitors are discussed. The problems of capacitors in a radiation environment are considered. Areas are defined where future research is needed. Some directions that this research should take are suggested

  12. A compact 100 kV high voltage glycol capacitor.

    Science.gov (United States)

    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.

  13. High power density capacitor and method of fabrication

    Science.gov (United States)

    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.

  14. Super capacitor modeling with artificial neural network (ANN)

    Energy Technology Data Exchange (ETDEWEB)

    Marie-Francoise, J.N.; Gualous, H.; Berthon, A. [Universite de Franche-Comte, Lab. en Electronique, Electrotechnique et Systemes (L2ES), UTBM, INRETS (LRE T31) 90 - Belfort (France)

    2004-07-01

    This paper presents super-capacitors modeling using Artificial Neural Network (ANN). The principle consists on a black box nonlinear multiple inputs single output (MISO) model. The system inputs are temperature and current, the output is the super-capacitor voltage. The learning and the validation of the ANN model from experimental charge and discharge of super-capacitor establish the relationship between inputs and output. The learning and the validation of the ANN model use experimental results of 2700 F, 3700 F and a super-capacitor pack. Once the network is trained, the ANN model can predict the super-capacitor behaviour with temperature variations. The update parameters of the ANN model are performed thanks to Levenberg-Marquardt method in order to minimize the error between the output of the system and the predicted output. The obtained results with the ANN model of super-capacitor and experimental ones are in good agreement. (authors)

  15. Method of manufacturing a shapeable short-resistant capacitor

    Science.gov (United States)

    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.

  16. MOSFET and MOS capacitor responses to ionizing radiation

    Science.gov (United States)

    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.

  17. Experimental analysis of an MIM capacitor with a concave shield

    International Nuclear Information System (INIS)

    Liu Lintao; Yu Mingyan; Wang Jinxiang

    2009-01-01

    A novel shielding scheme is developed by inserting a concave shield between a metal-insulator-metal (MIM) capacitor and the silicon substrate. Chip measurements reveal that the concave shield improves the quality factor by 11% at 11.8 GHz and 14% at 18.8 GHz compared with an unshielded MIM capacitor. It also alleviates the effect on shunt capacitance between the bottom plate of the MIM capacitor and the shield layer. Moreover, because the concave shields simplify substrate modeling, a simple circuit model of the MIM capacitor with concave shield is presented for radio frequency applications.

  18. Evaluation of Case Size 0603 BME Ceramic Capacitors

    Science.gov (United States)

    Teverovsky, Alexander A.

    2015-01-01

    High volumetric efficiency of commercial base metal electrode (BME) ceramic capacitors allows for a substantial reduction of weight and sizes of the parts compared to currently used military grade precious metal electrode (PME) capacitors. Insertion of BME capacitors in space applications requires a thorough analysis of their performance and reliability. In this work, six types of cases size 0603 BME capacitors from three vendors have been evaluated. Three types of multilayer ceramic capacitors (MLCCs) were designed for automotive industry and three types for general purposes. Leakage currents in the capacitors have been measured in a wide range of voltages and temperatures, and measurements of breakdown voltages (VBR) have been used to assess the proportion and severity of defects in the parts. The effect of soldering-related thermal shock stresses was evaluated by analysis of distributions of VBR for parts in 'as is' condition and after terminal solder dip testing at 350 C. Highly Accelerated Life Testing (HALT) at different temperatures was used to assess the activation energy of degradation of leakage currents and predict behavior of the parts at life test and normal operating conditions. To address issues related to rework and manual soldering, capacitors were soldered onto different substrates at different soldering conditions. The results show that contrary to a common assumption that large-size capacitors are mostly vulnerable to soldering stresses, cracking in small size capacitors does happen unless special measures are taken during assembly processes.

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

    International Nuclear Information System (INIS)

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

    1999-01-01

    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

  20. Accelerated Aging Experiments for Capacitor Health Monitoring and Prognostics

    Data.gov (United States)

    National Aeronautics and Space Administration — This paper discusses experimental setups for health monitoring and prognostics of electrolytic capacitors under nominal operation and accelerated aging conditions....

  1. Aging Methodologies and Prognostic Health Management for Electrolytic Capacitors

    Data.gov (United States)

    National Aeronautics and Space Administration — Understanding the ageing mechanisms of electronic components critical avionics systems such as the GPS and INAV are of critical importance. Electrolytic capacitors...

  2. Nonmedical application of computed tomography to power capacitor quality assesment

    International Nuclear Information System (INIS)

    Kruger, R.P.

    1981-01-01

    Present research and development efforts at Los Alamos Scientific Laboratory require the design and use of high-efficiency rapid-discharge energy storage capacitors for laser isotope separation and plasma physics programs. In these applications, capacitors are subjected to electrical, mechanical, thermal, and other environmental stresses. These stresses cause the dielectric constant to change due to gasification from arcing at nonsoldering connections, which produce a chemical reduction of the dielectric material. This effectively limits the lifetime of the capacitor. The programs mentioned above require capacitors with a multikilohertz frequency response at a current of tens of kiloamperes and a voltage of at least 100 kV. The lifetime of such capacitors should exceed 10 10 charge/discharge cycles. Such capacitors do not presently exist. The exploration of new capacitor designs will require the use of both electrical functional tests and tests that show the changes in internal physical structure as the capacitor is repeatedly stressed by the charge/discharge cycle. The integration of electrical and structural tests throughout the life cycle of a candidate capacitor makes it imperative that the structural integrity tests be nondestructive. Computed tomography (CT) makes this integration possible. The work reported here is the result of a pilot project designed to show the potential use of CT for this application. This work includes visualization of material defects using both a layered sequence of conventional tomographic slices and orthogonal multiangular pseudoradiographs generated from these slices

  3. Pencil-on-Paper Capacitors for Hand-Drawn RC Circuits and Capacitive Sensing

    Directory of Open Access Journals (Sweden)

    Jonathan E. Thompson

    2017-01-01

    Full Text Available Electronic capacitors were constructed via hand-printing on paper using pencil graphite. Graphite traces were used to draw conductive connections and capacitor plates on opposing sides of a sheet of standard notebook paper. The paper served as the dielectric separating the plates. Capacitance of the devices was generally < 1000 pF and scaled with surface area of the plate electrodes. By combining a pencil-drawn capacitor with an additional resistive pencil trace, an RC low-pass filter was demonstrated. Further utility of the pencil-on-paper devices was demonstrated through description of a capacitive force transducer and reversible chemical sensing. The latter was achieved for water vapor when the hygroscopic cellulose matrix of the paper capacitor’s dielectric adsorbed water. The construction and demonstration of pencil-on-paper capacitive elements broadens the scope of paper-based electronic circuits while allowing new opportunities in the rapidly expanding field of paper-based sensors.

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

    Science.gov (United States)

    Kaufman, David Y [Chicago, IL; Saha, Sanjib [Santa Clara, CA

    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.

  5. Historical reconstruction of polychlorinated biphenyl (PCB) exposures for workers in a capacitor manufacturing plant.

    Science.gov (United States)

    Hopf, Nancy B; Ruder, Avima M; Waters, Martha A

    2014-05-01

    We developed a semiquantitative job exposure matrix (JEM) for workers exposed to polychlorinated biphenyls (PCBs) at a capacitor manufacturing plant from 1946 to 1977. In a recently updated mortality study, mortality of prostate and stomach cancer increased with increasing levels of cumulative exposure estimated with this JEM (trend p values = 0.003 and 0.04, respectively). Capacitor manufacturing began with winding bales of foil and paper film, which were placed in a metal capacitor box (pre-assembly), and placed in a vacuum chamber for flood-filling (impregnation) with dielectric fluid (PCBs). Capacitors dripping with PCB residues were then transported to sealing stations where ports were soldered shut before degreasing, leak testing, and painting. Using a systematic approach, all 509 unique jobs identified in the work histories were rated by predetermined process- and plant-specific exposure determinants; then categorized based on the jobs' similarities (combination of exposure determinants) into 35 job exposure categories. The job exposure categories were ranked followed by a qualitative PCB exposure rating (baseline, low, medium, and high) for inhalation and dermal intensity. Category differences in other chemical exposures (solvents, etc.) prevented further combining of categories. The mean of all available PCB concentrations (1975 and 1977) for jobs within each intensity rating was regarded as a representative value for that intensity level. Inhalation (in microgram per cubic milligram) and dermal (unitless) exposures were regarded as equally important. Intensity was frequency adjusted for jobs with continuous or intermittent PCB exposures. Era-modifying factors were applied to the earlier time periods (1946-1974) because exposures were considered to have been greater than in later eras (1975-1977). Such interpolations, extrapolations, and modifying factors may introduce non-differential misclassification; however, we do believe our rigorous method

  6. Physics based Degradation Modeling and Prognostics of Electrolytic Capacitors under Electrical Overstress Conditions

    Data.gov (United States)

    National Aeronautics and Space Administration — This paper proposes a physics based degradation modeling and prognostics approach for electrolytic capacitors. Electrolytic capacitors are critical components in...

  7. Prognostics Health Management and Physics based failure Models for Electrolytic Capacitors

    Data.gov (United States)

    National Aeronautics and Space Administration — This paper proposes first principles based modeling and prognostics approach for electrolytic capacitors. Electrolytic capacitors and MOSFETs are the two major...

  8. Solid-state fractional capacitor using MWCNT-epoxy nanocomposite

    Science.gov (United States)

    John, Dina A.; Banerjee, Susanta; Bohannan, Gary W.; Biswas, Karabi

    2017-04-01

    Here, we propose the fabrication of a solid state fractional capacitor for which constant phase (CP) angles were attained in different frequency zones: 110 Hz-1.1 kHz, 10 kHz-118 kHz, and 230 kHz-20 MHz. The configuration makes use of epoxy resin as the matrix in which multi-walled carbon nanotubes (MWCNTs) are dispersed. Adhesive nature of the epoxy resin is utilized for binding the electrodes, which avoids the extra step for packaging. The fractional capacitive behavior is contributed by the distribution of time constants for the electron to travel from one electrode to the other. The distributive nature of the time constant is ensured by inserting a middle plate which is coated with a porous film of polymethyl-methacrylate in between the two electrodes. The phase angle trend for the configuration is studied in detail, and it is observed that as the % of carbon nanotubes (CNTs) loading increases, the CP angle increases from - 85 ° to - 45 ° in the frequency zones above 100 Hz. The developed device is compact and it can be easily integrated with the electronic circuits.

  9. Impedance Characteristics Modeling of a Two-Terminal Active Capacitor

    DEFF Research Database (Denmark)

    Wang, Haoran; Wang, Huai; Lu, Minghui

    2017-01-01

    to overcome the above issues. In this paper, the modeling of the active capacitor is investigated and a voltage feed-forward compensation scheme is proposed for overshoot reduction. Therefore, the impedance, equivalent capacitance, ESR, and ESL, of the active capacitor can be specified. A case study based...

  10. Physicochemical assessment criteria for high-voltage pulse capacitors

    Energy Technology Data Exchange (ETDEWEB)

    Darian, L. A., E-mail: LDarian@rambler.ru; Lam, L. Kh. [National Research University, Moscow Power Engineering Institute (Russian Federation)

    2016-12-15

    In the paper, the applicability of decomposition products of internal insulation of high-voltage pulse capacitors is considered (aging is the reason for decomposition products of internal insulation). Decomposition products of internal insulation of high-voltage pulse capacitors can be used to evaluate their quality when in operation and in service. There have been three generations of markers of aging of insulation as in the case with power transformers. The area of applicability of markers of aging of insulation for power transformers has been studied and the area can be extended to high-voltage pulse capacitors. The research reveals that there is a correlation between the components and quantities of markers of aging of the first generation (gaseous decomposition products of insulation) dissolved in insulating liquid and the remaining life of high-voltage pulse capacitors. The application of markers of aging to evaluate the remaining service life of high-voltage pulse capacitor is a promising direction of research, because the design of high-voltage pulse capacitors keeps stability of markers of aging of insulation in high-voltage pulse capacitors. It is necessary to continue gathering statistical data concerning development of markers of aging of the first generation. One should also carry out research aimed at estimation of the remaining life of capacitors using markers of the second and the third generation.

  11. Trench capacitor and method for producing the same

    NARCIS (Netherlands)

    2009-01-01

    A method of fabricating a trench capacitor, and a trench capacitor fabricated thereby, are disclosed. The method involves the use of a vacuum impregnation process for a sol-gel film, to facilitate effective deposition of high- permittivity materials within a trench in a semiconductor substrate, to

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

    Science.gov (United States)

    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)

  13. DC-to-DC converter comprising a reconfigurable capacitor unit

    NARCIS (Netherlands)

    2008-01-01

    The present invention relates to a configurable trench multi-capacitor device comprising a trench in a semiconductor substrate. The trench has a lateral extension exceeding 10 micrometer and a trench filling includes a number of at least four electrically conductive capacitor-electrode layers. A

  14. Direct Mismatch Characterization of femto-Farad Capacitors

    KAUST Repository

    Omran, Hesham

    2015-08-17

    Reducing the capacitance of programmable capacitor arrays, commonly used in analog integrated circuits, is necessary for low-energy applications. However, limited mismatch data is available for small capacitors. We report mismatch measurement for a 2fF poly-insulator-poly (PIP) capacitor, which is the smallest reported PIP capacitor to the best of the authors’ knowledge. Instead of using complicated custom onchip circuitry, direct mismatch measurement is demonstrated and verified using Monte Carlo Simulations and experimental measurements. Capacitive test structures composed of 9 bit programmable capacitor arrays (PCAs) are implemented in a low-cost 0:35m CMOS process. Measured data is compared to mismatch of large PIP capacitors, theoretical models, and recently published data. Measurement results indicate an estimated average relative standard deviation of 0.43% for the 2fF unit capacitor, which is better than the reported mismatch of metal-oxide-metal (MOM) fringing capacitors implemented in an advanced 32nm CMOS process.

  15. Powder based superdielectric materials for novel Capacitor design

    Science.gov (United States)

    2017-06-01

    found in cars, smartphones and other devices have adequate energy densities but lack optimal electric power delivery performance [4]. Stated differently... physical damage to the electrodes [5]. Conversely, capacitors store energy electrostatically by releasing excited state electrons collected on a...overview of capacitor theory is presented as a means of highlighting key physics principles applicable to this research. First, the concept of

  16. NEPP Evaluation of Automotive Grade Tantalum Chip Capacitors

    Science.gov (United States)

    Sampson, Mike; Brusse, Jay

    2018-01-01

    Automotive grade tantalum (Ta) chip capacitors are available at lower cost with smaller physical size and higher volumetric efficiency compared to military/space grade capacitors. Designers of high reliability aerospace and military systems would like to take advantage of these attributes while maintaining the high standards for long-term reliable operation they are accustomed to when selecting military-qualified established reliability tantalum chip capacitors (e.g., MIL-PRF-55365). The objective for this evaluation was to assess the long-term performance of off-the-shelf automotive grade Ta chip capacitors (i.e., manufacturer self-qualified per AEC Q-200). Two (2) lots of case size D manganese dioxide (MnO2) cathode Ta chip capacitors from 1 manufacturer were evaluated. The evaluation consisted of construction analysis, basic electrical parameter characterization, extended long-term (2000 hours) life testing and some accelerated stress testing. Tests and acceptance criteria were based upon manufacturer datasheets and the Automotive Electronics Council's AEC Q-200 qualification specification for passive electronic components. As-received a few capacitors were marginally above the specified tolerance for capacitance and ESR. X-ray inspection found that the anodes for some devices may not be properly aligned within the molded encapsulation leaving less than 1 mil thickness of the encapsulation. This evaluation found that the long-term life performance of automotive grade Ta chip capacitors is generally within specification limits suggesting these capacitors may be suitable for some space applications.

  17. Metallized Film Capacitor Lifetime Evaluation and Failure Mode Analysis

    CERN Document Server

    Gallay, R.

    2015-06-15

    One of the main concerns for power electronic engineers regarding capacitors is to predict their remaining lifetime in order to anticipate costly failures or system unavailability. This may be achieved using a Weibull statistical law combined with acceleration factors for the temperature, the voltage, and the humidity. This paper discusses the different capacitor failure modes and their effects and consequences.

  18. Nanostructured Anodic Multilayer Dielectric Stacked Metal-Insulator-Metal Capacitors.

    Science.gov (United States)

    Karthik, R; Kannadassan, D; Baghini, Maryam Shojaei; Mallick, P S

    2015-12-01

    This paper presents the fabrication of Al2O3/TiO2/Al2O3 metal-insulator-metal (MIM) capacitor using anodization technique. High capacitance density of > 3.5 fF/μm2, low quadratic voltage coefficient of capacitance of dielectric stack required for high performance MIM capacitor.

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

    Science.gov (United States)

    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. DC-to-DC converter comprising a reconfigurable capacitor unit

    NARCIS (Netherlands)

    Klootwijk, J.H.; Bergveld, H.J.; Roozeboom, F.; Reefman, D.; Ruigrok, J.

    2013-01-01

    The present invention relates to a configurable trench multi-capacitor device comprising a trench in a semiconductor substrate. The trench has a lateral extension exceeding 10 micrometer and a trench filling includes a number of at least four electrically conductive capacitor-electrode layers. A

  1. Physicochemical assessment criteria for high-voltage pulse capacitors

    International Nuclear Information System (INIS)

    Darian, L. A.; Lam, L. Kh.

    2016-01-01

    In the paper, the applicability of decomposition products of internal insulation of high-voltage pulse capacitors is considered (aging is the reason for decomposition products of internal insulation). Decomposition products of internal insulation of high-voltage pulse capacitors can be used to evaluate their quality when in operation and in service. There have been three generations of markers of aging of insulation as in the case with power transformers. The area of applicability of markers of aging of insulation for power transformers has been studied and the area can be extended to high-voltage pulse capacitors. The research reveals that there is a correlation between the components and quantities of markers of aging of the first generation (gaseous decomposition products of insulation) dissolved in insulating liquid and the remaining life of high-voltage pulse capacitors. The application of markers of aging to evaluate the remaining service life of high-voltage pulse capacitor is a promising direction of research, because the design of high-voltage pulse capacitors keeps stability of markers of aging of insulation in high-voltage pulse capacitors. It is necessary to continue gathering statistical data concerning development of markers of aging of the first generation. One should also carry out research aimed at estimation of the remaining life of capacitors using markers of the second and the third generation.

  2. Charging damage in floating metal-insulator-metal capacitors

    NARCIS (Netherlands)

    Ackaert, Jan; Wang, Zhichun; De Backer, E.; Coppens, P.

    2002-01-01

    In this paper, charging induced damage (CID) to metal-insulator-metal capacitors (MIMC) is reported. The damage is caused by the build up of a voltage potential difference between the two plates of the capacitor. A simple logarithmic relation is discovered between the damage by this voltage

  3. Direct Mismatch Characterization of femto-Farad Capacitors

    KAUST Repository

    Omran, Hesham; Elafandy, Rami T.; Arsalan, Muhammad; Salama, Khaled N.

    2015-01-01

    Reducing the capacitance of programmable capacitor arrays, commonly used in analog integrated circuits, is necessary for low-energy applications. However, limited mismatch data is available for small capacitors. We report mismatch measurement for a 2fF poly-insulator-poly (PIP) capacitor, which is the smallest reported PIP capacitor to the best of the authors’ knowledge. Instead of using complicated custom onchip circuitry, direct mismatch measurement is demonstrated and verified using Monte Carlo Simulations and experimental measurements. Capacitive test structures composed of 9 􀀀 bit programmable capacitor arrays (PCAs) are implemented in a low-cost 0:35m CMOS process. Measured data is compared to mismatch of large PIP capacitors, theoretical models, and recently published data. Measurement results indicate an estimated average relative standard deviation of 0.43% for the 2fF unit capacitor, which is better than the reported mismatch of metal-oxide-metal (MOM) fringing capacitors implemented in an advanced 32nm CMOS process.

  4. Matrix theory

    CERN Document Server

    Franklin, Joel N

    2003-01-01

    Mathematically rigorous introduction covers vector and matrix norms, the condition-number of a matrix, positive and irreducible matrices, much more. Only elementary algebra and calculus required. Includes problem-solving exercises. 1968 edition.

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

    Science.gov (United States)

    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

    Science.gov (United States)

    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. Problems of increasing specific characteristics of pulse capacitors and cables

    International Nuclear Information System (INIS)

    Kuchinskij, G.S.; Monastyrskij, A.E.; Shilin, O.V.

    1984-01-01

    Requirements for high specific energy are practically related to all types of pulse capacitors of energy storage. At present the specific energy for most types of home and foreign pulse capacitors is about 0.1 MJ/m 3 at operating electric field intensity 70-100 kV/mm. It is shown that the basic means for increasing the specific energy and working intensity is the application of new polymeric film materials. Application of paper-film and film insulation permits to develop the specific types of capacitors designed for a limited service life in an aperiodic discharge mode with lower reliabiliy and the specific energy upto 0.5 MJ/m 3 . Characteristics of separate types of pulse capacitors and cables are given, and reliability criterion is considered. Measures of increasing reliability and service life for pulse capacitors and cables, used as tokamak power supplies are enumerated

  8. Reliability of capacitors for DC-link applications - An overview

    DEFF Research Database (Denmark)

    Wang, Huai; Blaabjerg, Frede

    2013-01-01

    DC-link capacitors are an important part in the majority of power electronic converters which contribute to cost, size and failure rate on a considerable scale. From capacitor users' viewpoint, this paper presents a review on the improvement of reliability of DC-link in power electronic converters...... from two aspects: 1) reliability-oriented DC-link design solutions; 2) conditioning monitoring of DC-link capacitors during operation. Failure mechanisms, failure modes and lifetime models of capacitors suitable for the applications are also discussed as a basis to understand the physics......-of-failure. This review serves to provide a clear picture of the state-of-the-art research in this area and to identify the corresponding challenges and future research directions for capacitors and their DC-link applications....

  9. Evaluation of high temperature capacitor dielectrics

    Science.gov (United States)

    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.

  10. Development of High Temperature Capacitor Technology and Manufacturing Capability

    Energy Technology Data Exchange (ETDEWEB)

    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.

  11. Breakdown properties of irradiated MOS capacitors

    International Nuclear Information System (INIS)

    Paccagnella, A.; Candelori, A.; Pellizzer, F.; Fuochi, P.G.; Lavale, M.

    1996-01-01

    The authors have studied the effects of ionizing and non-ionizing radiation on the breakdown properties of different types of MOS capacitors, with thick (200 nm) and thin (down to 8 nm) oxides. In general, no large variations of the average breakdown field, time-to-breakdown at constant voltage, or charge-to-breakdown at constant voltage, or charge-to-breakdown values have been observed after high dose irradiation (20 Mrad(Si) 9 MeV electrons on thin and thick oxides, 17(Si) Mrad Co 60 gamma and 10 14 neutrons/cm 2 only on thick oxides). However, some modifications of the cumulative failure distributions have been observed in few of the oxides tested

  12. Laboratory-scale thyristor controlled series capacitor

    Energy Technology Data Exchange (ETDEWEB)

    Matsuki, J.; Ikeda, K.; Abe, M. [Kyoto University, Kyoto (Japan)

    1996-10-20

    This paper describes the results of an experimental study on the characteristics of a thyristor controlled series capacitor (TCSC). At present, there are two major thyristor controlled series compensation projects in the U.S.: the Kayenta ASC and the Slatt TCSC. However, there has been little operating experience and thus further understanding of the characteristics of TCSC is still to be sought. Therefore, a laboratory-scale TCSC was produced and installed in a laboratory power system. The impedance characteristics, waveshapes of voltages and currents in the TCSC circuit, and harmonics, for various thyristor firing angles, and insertion responses were measured and analyzed. In particular, effects of the size of the circuit components, i.e., parasitic resistance, additional damping resistance and series reactor, on the overall TCSC performances were investigated. The results were compared with EMTP simulations. 10 refs., 7 figs.

  13. Capacitor with a composite carbon foam electrode

    Science.gov (United States)

    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. Design definition of a mechanical capacitor

    Science.gov (United States)

    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.

  15. Chemical sensitivity of Mo gate Mos capacitors

    Energy Technology Data Exchange (ETDEWEB)

    Lombardi, R.M.; Aragon, R. [Laboratorio de Peliculas delgadas, Facultad de Ingenieria, Paseo Colon 850, 1063, Buenos Aires (Argentina)

    2006-07-01

    Mo gate Mos capacitors exhibit a negative shift of their C-V characteristic by up to 240 mV, at 125 C, in response to 1000 ppm hydrogen, in controlled nitrogen atmospheres. The experimental methods for obtaining capacitance and conductance, as a function of polarisation voltage, as well as the relevant equivalent circuits are reviewed. The single-state interface state density, at the semiconductor-dielectric interface, decreases from 2.66 x 10{sup 11} cm{sup -2} e-v{sup -1}, in pure nitrogen, to 2.5 x 10{sup 11} cm{sup -2} e-v{sup -1} in 1000 ppm hydrogen in nitrogen mixtures, at this temperature. (Author)

  16. Floating body cell a novel capacitor-less DRAM cell

    CERN Document Server

    Ohsawa, Takashi

    2011-01-01

    DRAM together with NAND Flash is driving semiconductor technologies with wide spectrum of usage ranging from PC, mobile phone and digital home appliances to solid-state disk (SSD). However, the DRAM cell which consists of a data storage capacitor (1C) and a switching transistor (1T) is facing serious difficulty in shrinking the size of the capacitor whose capacitance needs to be kept almost constant (20~30fF) throughout generations. The availability of a new DRAM cell which does not rely on an explicit capacitor for storing its data is more than ever awaited for further increasing the bit dens

  17. A light-powered bio-capacitor with nanochannel modulation.

    Science.gov (United States)

    Rao, Siyuan; Lu, Shanfu; Guo, Zhibin; Li, Yuan; Chen, Deliang; Xiang, Yan

    2014-09-03

    An artificial bio-capacitor system is established, consisting of the proton-pump protein proteorhodopsin and a modified alumina nanochannel, inspired by the capacitor-like behavior of plasma membranes realized through the cooperation of ion-pump and ion-channel proteins. Capacitor-like features of this simplified system are realized and identified, and the photocurrent duration time can be modulated by nanochannel modification to obtain favorable square-wave currents. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Comb-Line Filter with Coupling Capacitor in Ground Plane

    Directory of Open Access Journals (Sweden)

    Toshiaki Kitamura

    2011-01-01

    Full Text Available A comb-line filter with a coupling capacitor in the ground plane is proposed. The filter consists of two quarter-wavelength microstrip resonators. A coupling capacitor is inserted into the ground plane in order to build strong coupling locally along the resonators. The filtering characteristics are investigated through numerical simulations as well as experiments. Filtering characteristics that have attenuation poles at both sides of the passband are obtained. The input susceptances of even and odd modes and coupling coefficients are discussed. The filters using stepped impedance resonators (SIRs are also discussed, and the effects of the coupling capacitor for an SIR structure are shown.

  19. Barium titanate nanocomposite capacitor FY09 year end report.

    Energy Technology Data Exchange (ETDEWEB)

    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.

  20. Energy-Storing Structures: Composite Capacitors and Batteries

    Science.gov (United States)

    2012-07-30

    circuit board (PCB) prepreg C electrode dielectric Autoclave-processed structural capacitor • Objective: High energy density, scalable...Continued scaling (lab safety limit  100 J) – Beyond commercial FR4 prepreg  high dielectric additives, super- clean prepregging

  1. Li-Ion, Ultra-capacitor Based Hybrid Energy Module

    National Research Council Canada - National Science Library

    Daboussi, Zaher; Paryani, Anil; Khalil, Gus; Catherino, Henry; Gargies, Sonya

    2007-01-01

    Ultra-capacitors in multi kilo-farad ranges are now starting to be considered as alternatives or complimentary to batteries for products ranging from toys to hybrid vehicles as well as for space applications...

  2. RF MEMS Fractal Capacitors With High Self-Resonant Frequencies

    KAUST Repository

    Elshurafa, Amro M.; Emira, Ahmed; Radwan, Ahmed Gomaa; Salama, Khaled N.

    2012-01-01

    This letter demonstrates RF microelectromechanical systems (MEMS) fractal capacitors possessing the highest reported self-resonant frequencies (SRFs) in PolyMUMPS to date. Explicitly, measurement results show SRFs beyond 20 GHz. Furthermore, quality

  3. Tunable fractional-order capacitor using layered ferroelectric polymers

    KAUST Repository

    Agambayev, Agamyrat; Patole, Shashikant P.; Bagci, Hakan; Salama, Khaled N.

    2017-01-01

    Pairs of various Polyvinylidene fluoride P(VDF)-based polymers are used for fabricating bilayer fractional order capacitors (FOCs). The polymer layers are constructed using a simple drop casting approach. The resulting FOC has two advantages: It can

  4. Prognostic Techniques for Capacitor Degradation and Health Monitoring

    Data.gov (United States)

    National Aeronautics and Space Administration — This paper discusses our initial efforts in constructing physics of failure models for electrolytic capacitors subjected to electrical stressors in DC-DC power...

  5. Carbon-based fibrous EDLC capacitors and supercapacitors

    OpenAIRE

    Lekakou, C; Moudam, O; Markoulidis, F; Andrews, T; Watts, JF; Reed, GT

    2011-01-01

    This paper investigates electrochemical double-layer capacitors (EDLCs) including two alternative types of carbon-based fibrous electrodes, a carbon fibre woven fabric (CWF) and a multiwall carbon nanotube (CNT) electrode, as well as hybrid CWF-CNT electrodes. Two types of separator membranes were also considered. An organic gel electrolyte PEO-LiCIO4-EC-THF was used to maintain a high working voltage. The capacitor cells were tested in cyclic voltammetry, charge-discharge, and impedance test...

  6. Enhancement of dielectric breakdown strengths in polymer film capacitors

    International Nuclear Information System (INIS)

    Binder, M.; Mammone, R.J.; Lavene, B.; Rondeau, E.

    1992-01-01

    This paper reports that breakdown voltages of wound, polymer film/metal foil capacitors have been dramatically increased by briefly exposing them (after they had been spirally wound) to a low pressure, low temperature gas plasma. Exposure of wound, polycarbonate-based capacitors to a 96%CF 4 /4%O 2 gas plasma for 4 minutes, for example, produced a 200% increase in breakdown voltage

  7. CAPMIX -Deploying Capacitors for Salt Gradient Power Extraction

    OpenAIRE

    Bijmans, M.F.M.; Burheim, O.S.; Bryjak, M.; Delgado, A.; Hack, P.; Mantegazza, F.; Tenisson, S.; Hamelers, H.V.M.

    2012-01-01

    The process of mixing sea and river water can be utilised as a power source. At present, three groups of technology are established for doing so; i) mechanical; Pressure Retarded Osmosis PRO, ii) electrochemical reactions; Reverse ElectroDialysis (RED) and Nano Battery Electrodes (NBE) and iii) ultra capacitors; Capacitive Double Layer Expansion (CDLE) and Capacitors charge by the Donnan Potentials (CDP). The chemical potential for salt gradient power systems is only limited by th...

  8. Gas gain characteristics of parallel plate avalanche counter

    Energy Technology Data Exchange (ETDEWEB)

    Nishio, Katsuhisa; Yamamoto, Hideki; Kanno, Ikuo; Kimura, Itsuro [Kyoto Univ. (Japan). Faculty of Engineering; Nakagome, Y

    1996-07-01

    In the conventional gas gain theory, the Townsend primary ionization coefficient is expressed as a function of S, which is the ratio of the electric field strength (E) to the gas density (N). In this paper, an experimental form of {alpha} is derived from the data and is compared with the formula so far. (J.P.N.)

  9. Numerical modeling of parallel-plate based AMR

    DEFF Research Database (Denmark)

    comparison with experiment. This is used as a firm basis for predicting and optimizing performance of a large variety of regenerator configurations in order to study and learn the trends, tendencies and even absolute values of temperature span and cooling powers for the optimal (and buildable) designs...

  10. Fabrication of wound capacitors using flexible alkali-free glass

    International Nuclear Information System (INIS)

    Wilke, Rudeger H. T.; Baker, Amanda; Brown-Shaklee, Harlan; Johnson-Wilke, Raegan; Hettler, Chad

    2016-01-01

    Here, alkali-free glasses, which exhibit high energy storage densities (~35 J/cc), present a unique opportunity to couple high temperature stability with high breakdown strength, and thus provide an avenue for capacitor applications with stringent temperature and power requirements. Realizing the potential of these materials in kilovolt class capacitors with >1 J/cc recoverable energy density requires novel packaging strategies that incorporate these extremely fragile dielectrics. In this paper, we demonstrate the feasibility of fabricating wound capacitors using 50-μm-thick glass. Two capacitors were fabricated from 2.8-m-long ribbons of thin (50 μm) glass wound into 125-140-mm-diameter spools. The capacitors exhibit a capacitance of 70-75 nF with loss tangents below 1%. The wound capacitors can operate up to 1 kV and show excellent temperature stability to 150 °C. By improving the end terminations, the self-resonance can be shifted to above 1 MHz, indicating that these materials may be useful for pulsed power applications with microsecond discharge times.

  11. Physics Based Modeling and Prognostics of Electrolytic Capacitors

    Science.gov (United States)

    Kulkarni, Chetan; Ceyla, Jose R.; Biswas, Gautam; Goebel, Kai

    2012-01-01

    This paper proposes first principles based modeling and prognostics approach for electrolytic capacitors. Electrolytic capacitors have become critical components in electronics systems in aeronautics and other domains. Degradations and faults in DC-DC converter unit propagates to the GPS and navigation subsystems and affects the overall solution. Capacitors and MOSFETs are the two major components, which cause degradations and failures in DC-DC converters. This type of capacitors are known for its low reliability and frequent breakdown on critical systems like power supplies of avionics equipment and electrical drivers of electromechanical actuators of control surfaces. Some of the more prevalent fault effects, such as a ripple voltage surge at the power supply output can cause glitches in the GPS position and velocity output, and this, in turn, if not corrected will propagate and distort the navigation solution. In this work, we study the effects of accelerated aging due to thermal stress on different sets of capacitors under different conditions. Our focus is on deriving first principles degradation models for thermal stress conditions. Data collected from simultaneous experiments are used to validate the desired models. Our overall goal is to derive accurate models of capacitor degradation, and use them to predict performance changes in DC-DC converters.

  12. Discontinuous Galerkin Time-Domain Analysis of Power-Ground Planes Taking Into Account Decoupling Capacitors

    KAUST Repository

    Li, Ping

    2017-03-22

    In this paper, a discontinuous Galerkin time-domain (DGTD) method is developed to analyze the power-ground planes taking into account the decoupling capacitors. In the presence of decoupling capacitors, the whole physical system can be split into two subsystems: 1) the field subsystem that is governed by Maxwell\\'s equations that will be solved by the DGTD method, and 2) the circuit subsystem including the capacitor and its parasitic inductor and resistor, which is going to be characterized by the modified nodal analysis algorithm constructed circuit equations. With the aim to couple the two subsystems together, a lumped port is defined over a coaxial surface between the via barrel and the ground plane. To reach the coupling from the field to the circuit subsystem, a lumped voltage source calculated by the integration of electric field along the radial direction is introduced. On the other hand, to facilitate the coupling from the circuit to field subsystem, a lumped port current source calculated from the circuit equation is introduced, which serves as an impressed current source for the field subsystem. With these two auxiliary terms, a hybrid field-circuit matrix equation is established, which enables the field and circuit subsystems are solved in a synchronous scheme. Furthermore, the arbitrarily shaped antipads are considered by enforcing the proper wave port excitation using the magnetic surface current source derived from the antipads supported electric eigenmodes. In this way, the S-parameters corresponding to different modes can be conveniently extracted. To further improve the efficiency of the proposed algorithm in handling multiscale meshes, the local time-stepping marching scheme is applied. The proposed algorithm is verified by several representative examples.

  13. Matrix calculus

    CERN Document Server

    Bodewig, E

    1959-01-01

    Matrix Calculus, Second Revised and Enlarged Edition focuses on systematic calculation with the building blocks of a matrix and rows and columns, shunning the use of individual elements. The publication first offers information on vectors, matrices, further applications, measures of the magnitude of a matrix, and forms. The text then examines eigenvalues and exact solutions, including the characteristic equation, eigenrows, extremum properties of the eigenvalues, bounds for the eigenvalues, elementary divisors, and bounds for the determinant. The text ponders on approximate solutions, as well

  14. A review of Indirect Matrix Converter Topologies

    Directory of Open Access Journals (Sweden)

    Salem Rahmani

    2015-08-01

    Full Text Available Abstract—Matrix Converter (MC is a modern direct AC/AC electrical power converter without dc-link capacitor. MC is operated in four quadrant, assuring a control of the output voltage, amplitude and frequency. The matrix converter has recently attracted significant attention among researchers and it has become increasing attractive for applications of wind energy conversion, military power supplies, induction motor drives, etc. Recently, different MC topologies have been proposed and developed which have their own advantages and disadvantages. Matrix converter can be classified as direct and indirect structures. The direct one has been elaborated in previous work. In this paper the indirect MCs are reviewed. Different characteristics of the indirect MC topologies are mentioned to show the strengths and weaknesses of such converter topologies.

  15. Carbide Derived Carbon Super Capacitor Application

    Science.gov (United States)

    Appelgate, James; Bauer, Dave; Quirin, James; Lofland, S. E.; Hettinger, J. D.; Heon, M.; Gogotsi, Y.

    2010-02-01

    Supercapacitors can be applied into many different fields from nano-robots to high density energy storage. Growing TiC films from a know recipe and removing the transition metal element, Titanium, by chlorination leaves a carbon film that can then be applied as an electrode in a super capacitor. The problem is when the Titanium is removed from the film the stress induced by this process causes the films to fracture into isolated islands. The islands allow electrons to travel across them every easily, but there is no transfer of electrons from island to island. We present results of an investigation of a technique control the location of the fractures and use them to our benefit. Ideally, we want to create them to fracture in parallel lines. To force these fractures into straight lines we will purchase substrates with thermal SiO2 created on the surface of Si. Using an etching process we will removed a channel of SiO2 the same as the thickness of the TiC film we plan on growing. These channels will allow the fractures to form in a correlated way creating a straight line. )

  16. Low dielectric constant-based organic field-effect transistors and metal-insulator-semiconductor capacitors

    Science.gov (United States)

    Ukah, Ndubuisi Benjamin

    This thesis describes a study of PFB and pentacene-based organic field-effect transistors (OFET) and metal-insulator-semiconductor (MIS) capacitors with low dielectric constant (k) poly(methyl methacrylate) (PMMA), poly(4-vinyl phenol) (PVP) and cross-linked PVP (c-PVP) gate dielectrics. A physical method -- matrix assisted pulsed laser evaporation (MAPLE) -- of fabricating all-polymer field-effect transistors and MIS capacitors that circumvents inherent polymer dissolution and solvent-selectivity problems, is demonstrated. Pentacene-based OFETs incorporating PMMA and PVP gate dielectrics usually have high operating voltages related to the thickness of the dielectric layer. Reduced PMMA layer thickness (≤ 70 nm) was obtained by dissolving the PMMA in propylene carbonate (PC). The resulting pentacene-based transistors exhibited very low operating voltage (below -3 V), minimal hysteresis in their transfer characteristics, and decent electrical performance. Also low voltage (within -2 V) operation using thin (≤ 80 nm) low-k and hydrophilic PVP and c-PVP dielectric layers obtained via dissolution in high dipole moment and high-k solvents -- PC and dimethyl sulfoxide (DMSO), is demonstrated to be a robust means of achieving improved electrical characteristics and high operational stability in OFETs incorporating PVP and c-PVP dielectrics.

  17. Numerical Simulation of Tunneling Current in an Anisotropic Metal-Oxide-Semiconductor Capacitor

    Directory of Open Access Journals (Sweden)

    Khairurrijal khairurrijal

    2012-09-01

    Full Text Available In this paper, we have developed a model of the tunneling currents through a high-k dielectric stack in MOS capacitors with anisotropic masses. The transmittance was numerically calculated by employing a transfer matrix method and including longitudinal-transverse kinetic energy coupling which is represented by an electron phase velocity in the gate. The transmittance was then applied to calculate tunneling currents in TiN/HfSiOxN/SiO2/p-Si MOS capacitors. The calculated results show that as the gate electron velocity increases, the transmittance decreases and therefore the tunneling current reduces. The tunneling current becomes lower as the effective oxide thickness (EOT of HfSiOxN layer increases. When the incident electron passed through the barriers in the normal incident to the interface, the electron tunneling process becomes easier. It was also shown that the tunneling current was independent of the substrate orientation. Moreover, the model could be used in designing high speed MOS devices with low tunneling currents.

  18. BioCapacitor: A novel principle for biosensors.

    Science.gov (United States)

    Sode, Koji; Yamazaki, Tomohiko; Lee, Inyoung; Hanashi, Takuya; Tsugawa, Wakako

    2016-02-15

    Studies regarding biofuel cells utilizing biocatalysts such as enzymes and microorganisms as electrocatalysts have been vigorously conducted over the last two decades. Because of their environmental safety and sustainability, biofuel cells are expected to be used as clean power generators. Among several principles of biofuel cells, enzyme fuel cells have attracted significant attention for their use as alternative energy sources for future implantable devices, such as implantable insulin pumps and glucose sensors in artificial pancreas and pacemakers. However, the inherent issue of the biofuel cell principle is the low power of a single biofuel cell. The theoretical voltage of biofuel cells is limited by the redox potential of cofactors and/or mediators employed in the anode and cathode, which are inadequate for operating any devices used for biomedical application. These limitations inspired us to develop a novel biodevice based on an enzyme fuel cell that generates sufficient stable power to operate electric devices, designated "BioCapacitor." To increase voltage, the enzyme fuel cell is connected to a charge pump. To obtain a sufficient power and voltage to operate an electric device, a capacitor is used to store the potential generated by the charge pump. Using the combination of a charge pump and capacitor with an enzyme fuel cell, high voltages with sufficient temporary currents to operate an electric device were generated without changing the design and construction of the enzyme fuel cell. In this review, the BioCapacitor principle is described. The three different representative categories of biodevices employing the BioCapacitor principle are introduced. Further, the recent challenges in the developments of self-powered stand-alone biodevices employing enzyme fuel cells combined with charge pumps and capacitors are introduced. Finally, the future prospects of biodevices employing the BioCapacitor principle are addressed. Copyright © 2015 The Authors

  19. TRATAMIENTO DE AGUAS RESIDUALES MEDIANTE REACTORES ANAERÓBICOS DE PLACAS VERTICALES PARALELAS EN ACRÍLICO TRATAMENTO DE ÁGUAS RESIDUÁRIAS POR REATORES ANAERÓBIOS DE PLACAS VERTICAIS PARALELAS EM ACRÍLICO WASTEWATER TREATMENT BY ANAEROBIC REACTORS OF VERTICAL PARALLEL PLATES IN ACRYLIC

    Directory of Open Access Journals (Sweden)

    Guillermo Chaux F

    2011-12-01

    % o tempo de detenção de 24 horas. A facilidade na operação do reactor torna viável como tratamento biológico anaeróbio de águas residuárias previamente decantadas.Some anaerobic filters with bed stone built in the department of Cauca (Colombia, are presenting problems of obstruction. If the stone is replaced by vertical parallel plates, it eliminates the problem of obstruction. This paper presents the development and results of a study performed in laboratory scale that evaluated the potential of anaerobic reactors of vertical parallel plates in acrylic to remove pollutants (organic matter and suspended solids.The anaerobic reactor of parallel plates in acrylic served as secondary treatment; was fed with wastewater effluent of an Imhoff Tank with average concentrations of 156 ± 14 mg/L B0D5, 438 ± 32 mg/L of COD and 98 ± 22 mg/L of total suspended solids. The reductions of COD and BOD in the reactor are over 50% and the reduction of suspended solids exceeded 60% for time of detention for 24 hours. The ease in operating the reactor makes it viable as anaerobic biological treatment of wastewater previously decanted.

  20. The design and implementation of on-line monitoring system for UHV compact shunt capacitors

    Science.gov (United States)

    Tao, Weiliang; Ni, Xuefeng; Lin, Hao; Jiang, Shengbao

    2017-08-01

    Because of the large capacity and compact structure of the UHV compact shunt capacitor, it is difficult to take effective measures to detect and prevent the faults. If the fault capacitor fails to take timely maintenance, it will pose a threat to the safe operation of the system and the life safety of the maintenance personnel. The development of UHV compact shunt capacitor on-line monitoring system can detect and record the on-line operation information of UHV compact shunt capacitors, analyze and evaluate the early fault warning signs, find out the fault capacitor or the capacitor with fault symptom, to ensure safe and reliable operation of the system.

  1. Degradation Effect on Reliability Evaluation of Aluminum Electrolytic Capacitor in Backup Power Converter

    DEFF Research Database (Denmark)

    Zhou, Dao; Wang, Huai; Blaabjerg, Frede

    2017-01-01

    DC capacitors in power electronic converters are a major constraint on improvement of power density as well as reliability. In this paper, according to the degradation data of electrolytic capacitors through the accelerated test, the time-to-failure of the capacitor cell is acquired and it can...... be further extended to lower stress levels. Then, in a case study of a fuel cell backup power application, the mission profile based lifetime expectancy of the individual capacitor and the capacitor bank is estimated in terms of the standby mode and operation mode. The lifetime prediction of the capacitor...

  2. Comparison of MOS capacitor and transistor postirradiation response

    International Nuclear Information System (INIS)

    McWhorter, P.J.; Fleetwood, D.M.; Pastorek, R.A.; Zimmerman, G.T.

    1989-01-01

    The postirradiation response of MOS capacitors and transistors fabricated on the same chip has been examined as a function of dose and anneal bias. A variety of analysis techniques are used to evaluate the postirradiation response of these structures, including low and high frequency capacitance-voltage techniques, subthreshold current-voltage techniques, and charge pumping. Though there are changes in the postirradiation energy spectrum of ΔD it , no clear evidence of defect transformation is observed on transistors or capacitors under any conditions examined. Postirradiation response at 80 degrees C is found to be similar in the two structures for low levels of damage (100 krad). For both structures, interface-trap densities continue to grow following irradiation under these conditions. In contrast, the postirradiation response of capacitors and transistors can differ qualitatively at higher levels of damage (1 Mrad), with interface-traps increasing postirradiation at 80 degrees C for transistors and annealing for capacitors. These results indicate that capacitor structures may not be suitable for hardness assurance studies that involve elevated temperature irradiations or postirradiation anneals

  3. Graphene-Based Flexible and Transparent Tunable Capacitors.

    Science.gov (United States)

    Man, Baoyuan; Xu, Shicai; Jiang, Shouzheng; Liu, Aihua; Gao, Shoubao; Zhang, Chao; Qiu, Hengwei; Li, Zhen

    2015-12-01

    We report a kind of electric field tunable transparent and flexible capacitor with the structure of graphene-Bi1.5MgNb1.5O7 (BMN)-graphene. The graphene films with low sheet resistance were grown by chemical vapor deposition. The BMN thin films were fabricated on graphene by using laser molecular beam epitaxy technology. Compared to BMN films grown on Au, the samples on graphene substrates show better quality in terms of crystallinity, surface morphology, leakage current, and loss tangent. By transferring another graphene layer, we fabricated flexible and transparent capacitors with the structure of graphene-BMN-graphene. The capacitors show a large dielectric constant of 113 with high dielectric tunability of ~40.7 % at a bias field of 1.0 MV/cm. Also, the capacitor can work stably in the high bending condition with curvature radii as low as 10 mm. This flexible film capacitor has a high optical transparency of ~90 % in the visible light region, demonstrating their potential application for a wide range of flexible electronic devices.

  4. Study of electric capacitors using Finite Element Method

    Directory of Open Access Journals (Sweden)

    Alina Neamț

    2012-12-01

    Full Text Available A capacitor is made of two armatures and a dielectric between the two armatures. In this paper, we are going to study the plane capacitor , which is made of two equal metal armatures, plane and parallel, having the S surface, situated at a distance d much shorter than the armatures dimensions, between which there is a liniar, homogenous and isotropic dielectric having a constant electrical permittivity.The purpose of studying the plane capacitor, through MEF, presented in this paper,is to establish the stress to which the dielectrics may be subject to, in daily practice, and the influence that their superposition in an electric field has, on each of them. The study of the plane capacitor , finalised with observations on the raise of the dependence of the electric field intensity in air on the size of the air layer and having as parameter the type of dielectric material introduced between the armatures, is an example of confirmation or invalidation of the possibility and utility of using layers of dielectrics between the armatures of the capacitors.

  5. Matrix thermalization

    International Nuclear Information System (INIS)

    Craps, Ben; Evnin, Oleg; Nguyen, Kévin

    2017-01-01

    Matrix quantum mechanics offers an attractive environment for discussing gravitational holography, in which both sides of the holographic duality are well-defined. Similarly to higher-dimensional implementations of holography, collapsing shell solutions in the gravitational bulk correspond in this setting to thermalization processes in the dual quantum mechanical theory. We construct an explicit, fully nonlinear supergravity solution describing a generic collapsing dilaton shell, specify the holographic renormalization prescriptions necessary for computing the relevant boundary observables, and apply them to evaluating thermalizing two-point correlation functions in the dual matrix theory.

  6. Matrix thermalization

    Science.gov (United States)

    Craps, Ben; Evnin, Oleg; Nguyen, Kévin

    2017-02-01

    Matrix quantum mechanics offers an attractive environment for discussing gravitational holography, in which both sides of the holographic duality are well-defined. Similarly to higher-dimensional implementations of holography, collapsing shell solutions in the gravitational bulk correspond in this setting to thermalization processes in the dual quantum mechanical theory. We construct an explicit, fully nonlinear supergravity solution describing a generic collapsing dilaton shell, specify the holographic renormalization prescriptions necessary for computing the relevant boundary observables, and apply them to evaluating thermalizing two-point correlation functions in the dual matrix theory.

  7. Matrix thermalization

    Energy Technology Data Exchange (ETDEWEB)

    Craps, Ben [Theoretische Natuurkunde, Vrije Universiteit Brussel (VUB), and International Solvay Institutes, Pleinlaan 2, B-1050 Brussels (Belgium); Evnin, Oleg [Department of Physics, Faculty of Science, Chulalongkorn University, Thanon Phayathai, Pathumwan, Bangkok 10330 (Thailand); Theoretische Natuurkunde, Vrije Universiteit Brussel (VUB), and International Solvay Institutes, Pleinlaan 2, B-1050 Brussels (Belgium); Nguyen, Kévin [Theoretische Natuurkunde, Vrije Universiteit Brussel (VUB), and International Solvay Institutes, Pleinlaan 2, B-1050 Brussels (Belgium)

    2017-02-08

    Matrix quantum mechanics offers an attractive environment for discussing gravitational holography, in which both sides of the holographic duality are well-defined. Similarly to higher-dimensional implementations of holography, collapsing shell solutions in the gravitational bulk correspond in this setting to thermalization processes in the dual quantum mechanical theory. We construct an explicit, fully nonlinear supergravity solution describing a generic collapsing dilaton shell, specify the holographic renormalization prescriptions necessary for computing the relevant boundary observables, and apply them to evaluating thermalizing two-point correlation functions in the dual matrix theory.

  8. Application of proton conducting polymeric electrolytes to electrochemical capacitors

    International Nuclear Information System (INIS)

    Morita, Masayuki; Qiao, Jin-Li; Yoshimoto, Nobuko; Ishikawa, Masashi

    2004-01-01

    Non-aqueous polymeric gel complexes composed of poly(ethylene oxide)-modified polymethacrylate (PEO-PMA) dissolving anhydrous H 3 PO 4 have been examined as solid electrolytes of electrochemical capacitors. High ionic conductivity of ∼10 -3 S cm -1 (at 70 deg. C) was obtained for non-aqueous gel systems based on PEO-PMA with proper amounts of organic plasticizers. The ionic conductivity depended on the composition of the gel, especially on the content of the dopant H 3 PO 4 . A test cell of the electric double layer capacitor (EDLC) was assembled using the present gel electrolyte with activated carbon fiber (ACF) cloth electrodes. It gave as high capacity as that obtained for the capacitor using an aqueous liquid electrolyte. High rate capability was obtained for the cell operating at 90 deg. C

  9. High Voltage Homemade Capacitor Charger for Plasma Focus System

    International Nuclear Information System (INIS)

    Abdul Halim Baijan; Azaman Ahmad; Rokiah Mohd Sabri; Siti Aiasah Hashim; Mohd Rizal Md Chulan; Wah, L.K.; Azhar Ahmad; Rosli Che Ros; Mohd Faiz Mohd Zin

    2015-01-01

    A high voltage capacitor charger has been designed and built to replace a high voltage charger type General Atomics CCDs Power Supply which was damaged. The fabrication design was using materials which were easily available in the local market. Among the main components of the high-voltage charger is a transformer for neon lights, variable transformer rated 0 - 240 V 1 KVA, and 240 V transformer isolator. The results of experiments that have been conducted shows that a homemade capacitor charger was able to charge high voltage capacitors up to the required voltage of which was 12 kV. However the time taken for charging is quite long, up to more than 6 minutes. (author)

  10. Gamma radiation in ceramic capacitors: a study for space missions

    Science.gov (United States)

    dos Santos Ferreira, Eduardo; Sarango Souza, Juliana

    2017-10-01

    We studied the real time effects of the gamma radiation in ceramic capacitors, in order to evaluate the effects of cosmic radiation on these devices. Space missions have electronic circuits with various types of devices, many studies have been done on semiconductor devices exposed to gamma radiation, but almost no studies for passive components, in particular ceramic capacitors. Commercially sold ceramic capacitors were exposed to gamma radiation, and the capacitance was measured before and after exposure. The results clearly show that the capacitance decreases with exposure to gamma radiation. We confirmed this observation in a real time capacitance measurement, obtained using a data logging system developed by us using the open source Arduino platform.

  11. Thyristor-controlled reactor improves series capacitor applications

    Energy Technology Data Exchange (ETDEWEB)

    Renz, K.W.; Thumm, G.; Weiss, S. [Siemens AG, Erlangen (Germany)

    1995-12-31

    Environmental considerations make it more and more difficult to plan and erect new transmission lines. FACTS (Flexible AC Transmission Systems) technology can provide devices to improve the utility of AC transmission lines. The innovative combination of conventional fixed series capacitors and thyristor controlled reactors as a new FACTS device was introduced into a transmission system in 1992. This Advanced Series Compensation (ASC) system provides many advantages not available with conventional fixed series capacitor installations such as flexible direct and continuous control of the compensation level, direct and smooth power flow control and improved capacitor bank protection. This new technology offers enhanced system flexibility by control of transmission line overload conditions, reduction in fault currents, sub-synchronous resonance (SSR) mitigation and network power oscillation damping. The world-first three-phase installation at Kayenta Substation, USA, demonstrates that modern FACTS devices using SVC thyristor valve technology can be designed and operated successfully. 6 refs, 7 figs

  12. PLZT capacitor and method to increase the dielectric constant

    Science.gov (United States)

    Taylor, Ralph S.; Fairchild, Manuel Ray; Balachjandran, Uthamalingam; Lee, Tae H.

    2017-12-12

    A ceramic-capacitor includes a first electrically-conductive-layer, a second electrically-conductive-layer arranged proximate to the first electrically-conductive-layer, and a dielectric-layer interposed between the first electrically-conductive-layer and the second electrically-conductive-layer. The dielectric-layer is formed of a lead-lanthanum-zirconium-titanate material (PLZT), wherein the PLZT is characterized by a dielectric-constant greater than 125, when measured at 25 degrees Celsius and zero Volts bias, and an excitation frequency of ten-thousand Hertz (10 kHz). A method for increasing a dielectric constant of the lead-lanthanum-zirconium-titanate material (PLZT) includes the steps of depositing PLZT to form a dielectric-layer of a ceramic-capacitor, and heating the ceramic-capacitor to a temperature not greater than 300.degree. C.

  13. Characterization system for research on energy storage capacitors

    Science.gov (United States)

    Noriega, J. R.; Iyore, O. D.; Budime, C.; Gnade, B.; Vasselli, J.

    2013-05-01

    In this work a characterization system for high energy-density capacitors is described and demonstrated. Capacitors are being designed using thin-film technology in an attempt to achieve higher energy-density levels by operating the devices at a high voltage. These devices are fabricated from layers of 100 nm aluminum and a layer of polyvinylidene fluoride-hexafluoropropylene on a polyethylene naphthalate plastic substrate. The devices have been designed to store electrical charge at up to 200 V. Characterizations of these devices focus on the measurement of capacitance vs bias voltage and temperature, equivalent series resistance, and charge/discharge cycles. For the purpose of the characterization of these capacitors, an electronic charge/discharge interface was designed and tested.

  14. Discontinuous Galerkin Time-Domain Analysis of Power-Ground Planes Taking Into Account Decoupling Capacitors

    KAUST Repository

    Li, Ping; Jiang, Li Jun; Bagci, Hakan

    2017-01-01

    In this paper, a discontinuous Galerkin time-domain (DGTD) method is developed to analyze the power-ground planes taking into account the decoupling capacitors. In the presence of decoupling capacitors, the whole physical system can be split

  15. Infant-mortality testing of high-energy-density capacitors used on Nova

    International Nuclear Information System (INIS)

    Merritt, B.T.; Whitham, K.

    1983-01-01

    Nova is a solid-state large laser for inertial-confinement fusion research. Its flashlamps are driven by a 60-MJ capacitor bank. Part of this bank is being built with high-energy-density capacitors, 52-μF, 22 kV, 12.5 kJ. A total of 2645 of these capacitors have been purchased from two manufacturers. Each capacitor was infant-mortality tested. The first test consisted of a high-potential test, bushing-to-case, since these capacitors have dual bushings. Then the capacitors were discharged 500 times with circuit conditions approximating the capacitors normal flashlamp load. Failure of either of these tests or if the capacitor was leaking was cause for rejection

  16. Infant mortality testing of high energy-density capacitors used on Nova

    International Nuclear Information System (INIS)

    Merritt, B.T.; Whitham, K.

    1983-01-01

    Nova is a solid state large laser for inertial confinement fusion research. Its flashlamps are driven by a 60 MJ capacitor bank. Part of this bank is being built with high energy-density capacitors, 52 μF, 22 KV, 12.5 KJ. A total of 2,645 of these capacitors have been purchased from two manufacturers. Each capacitor was infant mortality tested. The first test consisted of a high-potential test, bushing-to-case, since these capacitors have dual bushings. Then the capacitors were discharged 500 times with circuit conditions approximating the capacitors normal flashlamp load. Failure of either of these tests or if the capacitor was leaking was cause for rejection. The test results were remarkably good. Less than 0.5 percent failed the pulse-discharge test and less than 2.5 percent were rejected overall

  17. Reliability Modeling Development and Its Applications for Ceramic Capacitors with Base-Metal Electrodes (BMEs)

    Science.gov (United States)

    Liu, Donhang

    2014-01-01

    This presentation includes a summary of NEPP-funded deliverables for the Base-Metal Electrodes (BMEs) capacitor task, development of a general reliability model for BME capacitors, and a summary and future work.

  18. Reliability Evaluation of Base-Metal-Electrode Multilayer Ceramic Capacitors for Potential Space Applications

    Science.gov (United States)

    Liu, David (Donhang); Sampson, Michael J.

    2011-01-01

    Base-metal-electrode (BME) ceramic capacitors are being investigated for possible use in high-reliability spacelevel applications. This paper focuses on how BME capacitors construction and microstructure affects their lifetime and reliability. Examination of the construction and microstructure of commercial off-the-shelf (COTS) BME capacitors reveals great variance in dielectric layer thickness, even among BME capacitors with the same rated voltage. Compared to PME (precious-metal-electrode) capacitors, BME capacitors exhibit a denser and more uniform microstructure, with an average grain size between 0.3 and 0.5 m, which is much less than that of most PME capacitors. BME capacitors can be fabricated with more internal electrode layers and thinner dielectric layers than PME capacitors because they have a fine-grained microstructure and do not shrink much during ceramic sintering. This makes it possible for BME capacitors to achieve a very high capacitance volumetric efficiency. The reliability of BME and PME capacitors was investigated using highly accelerated life testing (HALT). Most BME capacitors were found to fail with an early avalanche breakdown, followed by a regular dielectric wearout failure during the HALT test. When most of the early failures, characterized with avalanche breakdown, were removed, BME capacitors exhibited a minimum mean time-to-failure (MTTF) of more than 105 years at room temperature and rated voltage. Dielectric thickness was found to be a critical parameter for the reliability of BME capacitors. The number of stacked grains in a dielectric layer appears to play a significant role in determining BME capacitor reliability. Although dielectric layer thickness varies for a given rated voltage in BME capacitors, the number of stacked grains is relatively consistent, typically around 12 for a number of BME capacitors with a rated voltage of 25V. This may suggest that the number of grains per dielectric layer is more critical than the

  19. SOGI-based capacitor voltage feedback active damping in LCL-filtered grid converters

    DEFF Research Database (Denmark)

    Xin, Zhen; Wang, Xiongfei; Loh, Poh Chiang

    2015-01-01

    The capacitor voltage feedback active damping control is an attractive way to suppress LCL-filter resonance especially for the systems where the capacitor voltage is used for grid synchronization, since no extra sensors are added. The derivative is the core of the capacitor voltage feedback active...... derivative is more suited for capacitor voltage feedback active damping control. Experimental results validate the effectiveness of the proposed method....

  20. Improved Battery Charger Circuit Utilizing Reduced DC-link Capacitors

    Directory of Open Access Journals (Sweden)

    Vencislav Valchev

    2017-11-01

    Full Text Available The article presents a comparison of advantages and disadvantages of a battery charger circuit with and without the use of DC-link capacitors in it. The specific application requirements, namely ultra-light electric vehicles, are set as lightness, efficiency and robustness of the design. Prove of greater reliability and improvement on maintenance costs without significant decrease in the quality of charging process with the removal of DC-link capacitors in rectifier and boost converter circuits is accomplished. The proposed circuit parameters are analyzed by carried out simulations.

  1. Pulse Capacitors for Next Generation Linear Colliders. Final Report

    International Nuclear Information System (INIS)

    Hooker, M.W.

    2000-01-01

    During this Phase I SBIR research program, Nanomaterials Research Corporation (NRC) successfully demonstrated high-voltage multilayer capacitors produced from sub-100 nm ceramic powders. The devices produced by NRC exhibited properties that make them particularly useful for pulse power applications. These properties include (1) high capacitance (2) low loss (3) high breakdown voltage (4) high insulation resistance and (5) rapid discharge characteristics. Furthermore, the properties of the nanostructured capacitors were consistently found to exceed those of components that represent the state of the art within the industry. Encouraged by these results, NRC is planning to submit a Phase II proposal with the objective of securing seed capital to continue this development effort

  2. RF MEMS Fractal Capacitors With High Self-Resonant Frequencies

    KAUST Repository

    Elshurafa, Amro M.

    2012-07-23

    This letter demonstrates RF microelectromechanical systems (MEMS) fractal capacitors possessing the highest reported self-resonant frequencies (SRFs) in PolyMUMPS to date. Explicitly, measurement results show SRFs beyond 20 GHz. Furthermore, quality factors higher than 4 throughout a band of 1-15 GHz and reaching as high as 28 were achieved. Additional benefits that are readily attainable from implementing fractal capacitors in MEMS are discussed, including suppressing residual stress warping, eliminating the need for etching holes, and reducing parasitics. The latter benefits were acquired without any fabrication intervention. © 2011 IEEE.

  3. The possibility of giant dielectric materials for multilayer ceramic capacitors.

    Science.gov (United States)

    Ishii, Tatsuya; Endo, Makoto; Masuda, Kenichiro; Ishida, Keisuke

    2013-02-11

    There have been numerous reports on discovery of giant dielectric permittivity materials called internal barrier layer capacitor in the recent years. We took particular note of one of such materials, i.e., BaTiO 3 with SiO 2 coating. It shows expressions of giant electric permittivity when processed by spark plasma sintering. So we evaluated various electrical characteristics of this material to find out whether it is applicable to multilayer ceramic capacitors. Our evaluation revealed that the isolated surface structure is the sole cause of expressions of giant dielectric permittivity.

  4. Capacitance-voltage characterization of fully silicided gated MOS capacitor

    International Nuclear Information System (INIS)

    Wang Baomin; Ru Guoping; Jiang Yulong; Qu Xinping; Li Bingzong; Liu Ran

    2009-01-01

    This paper investigates the capacitance-voltage (C-V) measurement on fully silicided (FUSI) gated metal-oxide-semiconductor (MOS) capacitors and the applicability of MOS capacitor models. When the oxide leakage current of an MOS capacitor is large, two-element parallel or series model cannot be used to obtain its real C-V characteristic. A three-element model simultaneously consisting of parallel conductance and series resistance or a four-element model with further consideration of a series inductance should be used. We employed the three-element and the four-element models with the help of two-frequency technique to measure the Ni FUSI gated MOS capacitors. The results indicate that the capacitance of the MOS capacitors extracted by the three-element model still shows some frequency dispersion, while that extracted by the four-element model is close to the real capacitance, showing little frequency dispersion. The obtained capacitance can be used to calculate the dielectric thickness with quantum effect correction by NCSU C-V program. We also investigated the influence of MOS capacitor's area on the measurement accuracy. The results indicate that the decrease of capacitor area can reduce the dissipation factor and improve the measurement accuracy. As a result, the frequency dispersion of the measured capacitance is significantly reduced, and real C-V characteristic can be obtained directly by the series model. In addition, this paper investigates the quasi-static C-V measurement and the photonic high-frequency C-V measurement on Ni FUSI metal gated MOS capacitor with a thin leaky oxide. The results indicate that the large tunneling current through the gate oxide significantly perturbs the accurate measurement of the displacement current, which is essential for the quasi-static C-V measurement. On the other hand, the photonic high-frequency C-V measurement can bypass the leakage problem, and get reliable low-frequency C-V characteristic, which can be used to

  5. Online MOS Capacitor Characterization in LabVIEW Environment

    Directory of Open Access Journals (Sweden)

    Chinmay K Maiti

    2009-08-01

    Full Text Available We present an automated evaluation procedure to characterize MOS capacitors involving high-k gate dielectrics. Suitability of LabVIEW environment for online web-based semiconductor device characterization is demonstrated. Developed algorithms have been successfully applied to automate the MOS capacitor measurements for Capacitance-Voltage, Conductance-Voltage and Current-Voltage characteristics. Implementation of the algorithm for use as a remote internet-based characterization tool where the client and server communicate with each other via web services is also shown.

  6. Atomic Layer Deposition Alumina-Passivated Silicon Nanowires: Probing the Transition from Electrochemical Double-Layer Capacitor to Electrolytic Capacitor.

    Science.gov (United States)

    Gaboriau, Dorian; Boniface, Maxime; Valero, Anthony; Aldakov, Dmitry; Brousse, Thierry; Gentile, Pascal; Sadki, Said

    2017-04-19

    Silicon nanowires were coated by a 1-5 nm thin alumina layer by atomic layer deposition (ALD) in order to replace poorly reproducible and unstable native silicon oxide by a highly conformal passivating alumina layer. The surface coating enabled probing the behavior of symmetric devices using such electrodes in the EMI-TFSI electrolyte, allowing us to attain a large cell voltage up to 6 V in ionic liquid, together with very high cyclability with less than 4% capacitance fade after 10 6 charge/discharge cycles. These results yielded fruitful insights into the transition between an electrochemical double-layer capacitor behavior and an electrolytic capacitor behavior. Ultimately, thin ALD dielectric coatings can be used to obtain hybrid devices exhibiting large cell voltage and excellent cycle life of dielectric capacitors, while retaining energy and power densities close to the ones displayed by supercapacitors.

  7. Integration substrate with a ultra-high-density capacitor and a through-substrate via

    NARCIS (Netherlands)

    2008-01-01

    An integration substrate for a system in package comprises a through-substrate via and a trench capacitor wherein with a trench filling that includes at least 4 elec. conductive capacitor-electrode layers in an alternating arrangement with dielec. layers. The capacitor-electrode layers are

  8. The Two-Capacitor Problem Revisited: A Mechanical Harmonic Oscillator Model Approach

    Science.gov (United States)

    Lee, Keeyung

    2009-01-01

    The well-known two-capacitor problem, in which exactly half the stored energy disappears when a charged capacitor is connected to an identical capacitor, is discussed based on the mechanical harmonic oscillator model approach. In the mechanical harmonic oscillator model, it is shown first that "exactly half" the work done by a constant applied…

  9. Integration substrate with a ultra-high-density capacitor and a through-substrate via

    NARCIS (Netherlands)

    Klootwijk, J.H.; Roozeboom, F.; Ruigrok, J.J.M.; Reefman, D.

    2014-01-01

    An integration substrate for a system in package comprises a through-substrate via and a trench capacitor wherein with a trench filling that includes at least four electrically conductive capacitor-electrode layers in an alternating arrangement with dielectric layers. --The capacitor-electrode

  10. A quick method to determine the capacitance characteristics of thin layer X5R multilayer capacitors

    NARCIS (Netherlands)

    Mikkenie, R.; Steigelmann, O.; Groen, W.A.; ten Elshof, Johan E.

    2012-01-01

    The effect of Y2O3 concentration on the dielectric properties of ceramic disc capacitors and multilayer capacitors containing 50 dielectric layers with an approximate thickness of 3 μm were investigated. The relative permittivity and temperature coefficient of capacity of multilayer capacitors at

  11. A quick method to determine the capacitance characteristics of thin layer X5R multilayer capacitors

    NARCIS (Netherlands)

    Mikkenie, R.; Steigelmann, O.; Groen, W.A.; Elshof, J.E. ten

    2012-01-01

    The effect of Y2O3 concentration on the dielectric properties of ceramic disc capacitors and multilayer capacitors containing 50 dielectric layers with an approximate thickness of 3µm were investigated. The relative permittivity and temperature coefficient of capacity of multilayer capacitors at low

  12. Microstrip Resonator for High Field MRI with Capacitor-Segmented Strip and Ground Plane

    DEFF Research Database (Denmark)

    Zhurbenko, Vitaliy; Boer, Vincent; Petersen, Esben Thade

    2017-01-01

    ) segmenting stripe and ground plane of the resonator with series capacitors. The design equations for capacitors providing symmetric current distribution are derived. The performance of two types of segmented resonators are investigated experimentally. To authors’ knowledge, a microstrip resonator, where both......, strip and ground plane are capacitor-segmented, is shown here for the first time....

  13. Reliability Evaluation of Base-Metal-Electrode (BME) Multilayer Ceramic Capacitors for Space Applications

    Science.gov (United States)

    Liu, David (Donghang)

    2011-01-01

    This paper reports reliability evaluation of BME ceramic capacitors for possible high reliability space-level applications. The study is focused on the construction and microstructure of BME capacitors and their impacts on the capacitor life reliability. First, the examinations of the construction and microstructure of commercial-off-the-shelf (COTS) BME capacitors show great variance in dielectric layer thickness, even among BME capacitors with the same rated voltage. Compared to PME (precious-metal-electrode) capacitors, BME capacitors exhibit a denser and more uniform microstructure, with an average grain size between 0.3 and approximately 0.5 micrometers, which is much less than that of most PME capacitors. The primary reasons that a BME capacitor can be fabricated with more internal electrode layers and less dielectric layer thickness is that it has a fine-grained microstructure and does not shrink much during ceramic sintering. This results in the BME capacitors a very high volumetric efficiency. The reliability of BME and PME capacitors was investigated using highly accelerated life testing (HALT) and regular life testing as per MIL-PRF-123. Most BME capacitors were found to fail· with an early dielectric wearout, followed by a rapid wearout failure mode during the HALT test. When most of the early wearout failures were removed, BME capacitors exhibited a minimum mean time-to-failure of more than 10(exp 5) years. Dielectric thickness was found to be a critical parameter for the reliability of BME capacitors. The number of stacked grains in a dielectric layer appears to play a significant role in determining BME capacitor reliability. Although dielectric layer thickness varies for a given rated voltage in BME capacitors, the number of stacked grains is relatively consistent, typically between 10 and 20. This may suggest that the number of grains per dielectric layer is more critical than the thickness itself for determining the rated voltage and the life

  14. Matrix inequalities

    CERN Document Server

    Zhan, Xingzhi

    2002-01-01

    The main purpose of this monograph is to report on recent developments in the field of matrix inequalities, with emphasis on useful techniques and ingenious ideas. Among other results this book contains the affirmative solutions of eight conjectures. Many theorems unify or sharpen previous inequalities. The author's aim is to streamline the ideas in the literature. The book can be read by research workers, graduate students and advanced undergraduates.

  15. Ceramic capacitor insulation resistance failures accelerated by low voltage

    Science.gov (United States)

    Brennan, T. F.

    1978-01-01

    Ceramic capacitors failed insulation resistance testing at less than one-tenth their rated voltage. Many failures recovered as the voltage was increased. Comprehensive failure analysis techniques, some of which are unprecedented, were used to examine these failures. It was determined that there was more than one failure mechanism, and the results indicate a need for special additional screening.

  16. Performance and Safety of Lithium-ion Capacitors

    Science.gov (United States)

    Jeevarajan, Judith A.; Martinez, Martin D.

    2014-01-01

    Lithium-ion capacitors (LIC) are a recent innovation in the area of supercapacitors and ultracapacitors. With an operating voltage range similar to that of lithium-ion batteries and a very low selfdischarge rate, these can be readily used in the place of batteries especially when large currents are required to be stored safely for use at a later time.

  17. Multi-step capacitor discharges as an RF generator

    International Nuclear Information System (INIS)

    Hotta, Eiki; Yamamoto, Shunji; Ishii, Shozo; Hayashi, Izumi

    1979-01-01

    A variety of methods have been developed for large output radio frequency (RF) generators to heat and stabilize high temperature plasma. As the generators for this purpose, capacitor discharge, cable discharge, and oscillation with electronic tubes are considered. Here, a new RF generator is reported, which utilizes capacitor discharge to extract heavy current, and solves the difficulty of short duration by employing multistep discharges. The authors solved the problem of frequency decrease in capacitor discharge by cutting off the unnecessary capacitors reasonably from the load circuit, using the additional circuit for shunting current and vacuum gap switches. The vacuum gap switches and the trigger system are described together with the RF generator manufactured. The generator was fabricated to be rather compact for its large output and simple in circuitry as compared with conventional oscillator systems. The shortcomings are frequency variation and the improper phase of switching the next step in to cause instability, when the load change occurs. It would be difficult to operate the generator in a RF range of more than about 10 MHz due to jitter of the vacuum gap switches and others. (Wakatsuki, Y.)

  18. Capacitor charging FET switcher with controller to adjust pulse width

    Science.gov (United States)

    Mihalka, Alex M.

    1986-01-01

    A switching power supply includes an FET full bridge, a controller to drive the FETs, a programmable controller to dynamically control final output current by adjusting pulse width, and a variety of protective systems, including an overcurrent latch for current control. Power MOSFETS are switched at a variable frequency from 20-50 kHz to charge a capacitor load from 0 to 6 kV. A ferrite transformer steps up the DC input. The transformer primary is a full bridge configuration with the FET switches and the secondary is fed into a high voltage full wave rectifier whose output is connected directly to the energy storage capacitor. The peak current is held constant by varying the pulse width using predetermined timing resistors and counting pulses. The pulse width is increased as the capacitor charges to maintain peak current. A digital ripple counter counts pulses, and after the desired number is reached, an up-counter is clocked. The up-counter output is decoded to choose among different resistors used to discharge a timing capacitor, thereby determining the pulse width. A current latch shuts down the supply on overcurrent due to either excessive pulse width causing transformer saturation or a major bridge fault, i.e., FET or transformer failure, or failure of the drive circuitry.

  19. Application of Electric Double Layer Capacitor for Solar Car

    OpenAIRE

    中西, 弘一; 岸, 純男; 仲森, 昌也; 荒賀, 浩一

    2016-01-01

    This paper describes a method for efficient work of electrical energy, using DC-DC converter as insulate between battery and Electrical Double Layer Capacitor (EDLC). In case of constant-current charge to the EDLC, the efficiency of the electric power is higher, compared to the constant-voltage charge.

  20. Analytical evaluation of DC capacitor RMS current and voltage ...

    Indian Academy of Sciences (India)

    K S GOPALAKRISHNAN

    The sizing of the DC-link capacitor in a three-level inverter is based on the RMS current flowing through it. ... Current control; current stress; diode-clamped inverter; full-bridge inverter; half-bridge inverter; ..... leg of an NPC inverter, is simulated using MATLAB .... actual q-axis current and the actual load current change at a.

  1. Harmonic analysis of DC capacitor current in sinusoidal and space ...

    Indian Academy of Sciences (India)

    DC capacitor current in a three-level neutral-point clamped (NPC) inverter, modu- lated with ... For control of the switches in two-level and three-level inverters, numerous pulse-width mod- ..... coincide with each other, and lie on the horizontal axis in figure 5b. The loci of the ... A MATLAB code is written for the purpose. 5.

  2. Linear variable voltage diode capacitor and adaptive matching networks

    NARCIS (Netherlands)

    Larson, L.E.; De Vreede, L.C.N.

    2006-01-01

    An integrated variable voltage diode capacitor topology applied to a circuit providing a variable voltage load for controlling variable capacitance. The topology includes a first pair of anti-series varactor diodes, wherein the diode power-law exponent n for the first pair of anti-series varactor

  3. All-printed capacitors with continuous solution dispensing technology

    Science.gov (United States)

    Ge, Yang; Plötner, Matthias; Berndt, Andreas; Kumar, Amit; Voit, Brigitte; Pospiech, Doris; Fischer, Wolf-Joachim

    2017-09-01

    Printed electronics have been introduced into the commercial markets in recent years. Various printing technologies have emerged aiming to process printed electronic devices with low cost, environmental friendliness, and compatibility with large areas and flexible substrates. The aim of this study is to propose a continuous solution dispensing technology for processing all-printed thin-film capacitors on glass substrates using a leading-edge printing instrument. Among all printing technologies, this study provides concrete proof of the following outstanding advantages of this technology: high tolerance to inks, high throughput, low cost, and precise pattern transfers. Ag nanoparticle ink based on glycol ethers was used to print the electrodes. To obtain dielectric ink, a copolymer powder of poly(methyl methacrylate-co-benzoylphenyl methacrylate) containing crosslinkable side groups was dissolved in anisole. Various layouts were designed to support multiple electronic applications. Scanning electron microscopy and atomic force microscopy were used to investigate the all-printed capacitor layers formed using the proposed process. Additionally, the printed capacitors were electrically characterized under direct current and alternating current. The measured electrical properties of the printed capacitors were consistent with the theoretical results.

  4. Optimal capacitor placement and sizing using combined fuzzy ...

    African Journals Online (AJOL)

    Then the sizing of the capacitors is modeled as an optimization problem and the objective function (loss minimization) is solved using Hybrid Particle Swarm Optimization (HPSO) technique. A case study with an IEEE 34 bus distribution feeder is presented to illustrate the applicability of the algorithm. A comparison is made ...

  5. Switchable capacitor and method of making the same

    NARCIS (Netherlands)

    Rottenberg, Xavier; Jansen, Henricus V.; Tilmans, Hendrikus; De Raedt, Walter

    2006-01-01

    A micro electromechanical switchable capacitor is disclosed, comprising a substrate, a bottom electrode, a dielectric layer deposited on at least part of said bottom electrode, a conductive floating electrode deposited on at least part of said dielectric layer, an armature positioned proximate to

  6. Novel dielectric reduces corona breakdown in ac capacitors

    Science.gov (United States)

    Loehner, J. L.

    1972-01-01

    Dielectric system was developed which consists of two layers of 25-gage paper separated by one layer of 50-gage polypropylene to reduce corona breakdown in ac capacitors. System can be used in any alternating current application where constant voltage does not exceed 400 V rms. With a little research it could probably be increased to 700 to 800 V rms.

  7. Switchable capacitor and method of making the same

    NARCIS (Netherlands)

    Rottenberg, Xavier; Jansen, Henricus V.; Tilmans, Hendrikus; De Raedt, Walter

    2003-01-01

    A micro electromechanical switchable capacitor is disclosed, comprising a substrate, a bottom electrode, a dielectric layer deposited on at least part of said bottom electrode, a conductive floating electrode deposited on at least part of said dielectric layer, an armature positioned proximate to

  8. Nanodomain Engineering in Ferroelectric Capacitors with Graphene Electrodes.

    Science.gov (United States)

    Lu, Haidong; Wang, Bo; Li, Tao; Lipatov, Alexey; Lee, Hyungwoo; Rajapitamahuni, Anil; Xu, Ruijuan; Hong, Xia; Farokhipoor, Saeedeh; Martin, Lane W; Eom, Chang-Beom; Chen, Long-Qing; Sinitskii, Alexander; Gruverman, Alexei

    2016-10-12

    Polarization switching in ferroelectric capacitors is typically realized by application of an electrical bias to the capacitor electrodes and occurs via a complex process of domain structure reorganization. As the domain evolution in real devices is governed by the distribution of the nucleation centers, obtaining a domain structure of a desired configuration by electrical pulsing is challenging, if not impossible. Recent discovery of polarization reversal via the flexoelectric effect has opened a possibility for deterministic control of polarization in ferroelectric capacitors. In this paper, we demonstrate mechanical writing of arbitrary-shaped nanoscale domains in thin-film ferroelectric capacitors with graphene electrodes facilitated by a strain gradient induced by a tip of an atomic force microscope (AFM). A phase-field modeling prediction of a strong effect of graphene thickness on the threshold load required to initiate mechanical switching has been confirmed experimentally. Deliberate voltage-free domain writing represents a viable approach for development of functional devices based on domain topology and electronic properties of the domains and domain walls.

  9. Carbons, ionic liquids and quinones for electrochemical capacitors

    Directory of Open Access Journals (Sweden)

    Raul eDiaz

    2016-04-01

    Full Text Available Carbons are the main electrode materials used in electrochemical capacitors, which are electrochemical energy storage devices with high power densities and long cycling lifetimes. However, increasing their energy density will improve their potential for commercial implementation. In this regard, the use of high surface area carbons and high voltage electrolytes are well known strategies to increase the attainable energy density, and lately ionic liquids have been explored as promising alternatives to current state of the art acetonitrile-based electrolytes. Also, in terms of safety and sustainability ionic liquids are attractive electrolyte materials for electrochemical capacitors. In addition, it has been shown that the matching of the carbon pore size with the electrolyte ion size further increases the attainable electric double layer (EDL capacitance and energy density.The use of pseudocapacitive reactions can significantly increase the attainable energy density, and quinonic-based materials offer a potentially sustainable and cost effective research avenue for both the electrode and the electrolyte. This perspective will provide an overview of the current state of the art research on electrochemical capacitors based on combinations of carbons, ionic liquids and quinonic compounds, highlighting performances and challenges and discussing possible future research avenues. In this regard, current interest is mainly focused on strategies which may ultimately lead to commercially competitive sustainable high performance electrochemical capacitors for different applications including those requiring mechanical flexibility and biocompatibility.

  10. Mismatch-Shaped Pseudo-Passive Two-Capacitor DAC

    DEFF Research Database (Denmark)

    Steensgaard-Madsen, Jesper; Moon, Un-Ku; Temes, Gabor C.

    1999-01-01

    A simple mismatch-shaping scheme is proposed for a two-capacitor DAC. Unlike in other mismatch-shaping systems, the shaped error is generated by direct filtering of a well-defined bounded signal, which can be generated as white noise. The operation is closely related to a specific digital...

  11. Plasma damage in floating metal-insulator-metal capacitors

    NARCIS (Netherlands)

    Ackaert, Jan; Wang, Zhichun; De Backer, E.; Coppens, P.

    2002-01-01

    In this paper, charging induced damage (CID) to metal-insulator-metal capacitors (MIMCs), is reported. CID does not necessarily lead to direct yield loss, but may also induce latent damage leading to reliability losses. The damage is caused by the build up of a voltage potential difference between

  12. Residual stresses in multilayer ceramic capacitors: measurement and computation

    NARCIS (Netherlands)

    Toonder, den J.M.J.; Rademaker, C.W.; Hu, C.L.

    2003-01-01

    In this paper, we present a combined experimental and computational study of the thermomechanical reliability of multilayer ceramic capacitors (MLCC's). We focus on residual stresses introduced into the components during the cooling down step of the sintering process. The technique of

  13. Mismatch-shaping switching for two-capacitor DAC

    DEFF Research Database (Denmark)

    Steensgaard-Madsen, Jesper; Moon, U.; Temes, G.C.

    1998-01-01

    A mismatch-shaping scheme is proposed for a two-capacitor digital-to-analogue converter (DAC). It uses a delta-sigma loop for finding the optimal switching sequence for each input word. Simulations indicate that the scheme can be used for the realisation of DACs with 16 bit linearity and SNR...

  14. Plasma Damage in Floating Metal-Insulator-Metal Capacitors

    NARCIS (Netherlands)

    Ackaert, Jan; Wang, Zhichun; Backer, E.; Coppens, P.

    2001-01-01

    In this paper, charging induced damage (CID) to metal-insulator-metal capacitors (MIMCs), is reported. CID does not necessarily lead to direct yield loss, but may also induce latent damage leading to reliability losses. The damage is caused by the build up of a voltage potential difference between

  15. Lifetime Estimation of Electrolytic Capacitors in Fuel Cell Power Converter at Various Confidence Levels

    DEFF Research Database (Denmark)

    Zhou, Dao; Wang, Huai; Blaabjerg, Frede

    2016-01-01

    DC capacitors in power electronic converters are a major constraint on improvement of the power density and the reliability. In this paper, according to the degradation data of tested capacitors, the lifetime model of the component is analyzed at various confidence levels. Then, the mission profile...... based lifetime expectancy of the individual capacitor and the capacitor bank is estimated in a fuel cell backup power converter operating in both standby mode and operation mode. The lifetime prediction of the capacitor banks at different confidence levels is also obtained....

  16. Highly Accurate Derivatives for LCL-Filtered Grid Converter with Capacitor Voltage Active Damping

    DEFF Research Database (Denmark)

    Xin, Zhen; Loh, Poh Chiang; Wang, Xiongfei

    2016-01-01

    The middle capacitor voltage of an LCL-filter, if fed back for synchronization, can be used for active damping. An extra sensor for measuring the capacitor current is then avoided. Relating the capacitor voltage to existing popular damping techniques designed with capacitor current feedback would...... are then proposed, based on either second-order or non-ideal generalized integrator. Performances of these derivatives have been found to match the ideal “s” function closely. Active damping based on capacitor voltage feedback can therefore be realized accurately. Experimental results presented have verified...

  17. Reliability-oriented Design of a Cost-effective Active Capacitor

    DEFF Research Database (Denmark)

    Wang, Haoran; Wang, Huai

    2017-01-01

    This paper presents the reliability-oriented design of a two-terminal active capacitor proposed recently. The two-terminal active capacitor has the same level of convenience as a passive capacitor with reduced requirement of overall energy storage. In order to fully explore the potential...... of the proposed concept, a comprehensive design procedure is necessary to optimally sizing the key components of the active capacitor in terms of cost and reliability. Moreover, the inherent condition monitoring capability of the active capacitor is discussed by utilizing the existing feedback signals. A 500 W...

  18. A new method of optimal capacitor switching based on minimum spanning tree theory in distribution systems

    Science.gov (United States)

    Li, H. W.; Pan, Z. Y.; Ren, Y. B.; Wang, J.; Gan, Y. L.; Zheng, Z. Z.; Wang, W.

    2018-03-01

    According to the radial operation characteristics in distribution systems, this paper proposes a new method based on minimum spanning trees method for optimal capacitor switching. Firstly, taking the minimal active power loss as objective function and not considering the capacity constraints of capacitors and source, this paper uses Prim algorithm among minimum spanning trees algorithms to get the power supply ranges of capacitors and source. Then with the capacity constraints of capacitors considered, capacitors are ranked by the method of breadth-first search. In term of the order from high to low of capacitor ranking, capacitor compensation capacity based on their power supply range is calculated. Finally, IEEE 69 bus system is adopted to test the accuracy and practicality of the proposed algorithm.

  19. Practical Considerations of the Start-up Procedure for an Active Capacitor

    DEFF Research Database (Denmark)

    Wang, Haoran; Wang, Qian; Geng, Tao

    2017-01-01

    Capacitive DC links provide the only low-impedance current path connected with an input source during the start-up of many voltage source converters. A soft-start circuit is usually implemented to limit the inrush current. A two-terminal active capacitor is recently proposed which can directly...... replace conventional passive capacitors in DC links, with reduced cost or size for a given application. The active capacitor has the same level of convenience with two power terminals only as a passive capacitor. This paper proposes two start-up schemes for the active capacitor to overcome the drawbacks...... of existing methods previously widely used for passive capacitors. One scheme is based on a trade-off design between the start-up performance and the component sizing of the active capacitor. The other scheme is based on either an additional bypass switch together with the existing soft-start circuit...

  20. Matrix analysis

    CERN Document Server

    Bhatia, Rajendra

    1997-01-01

    A good part of matrix theory is functional analytic in spirit. This statement can be turned around. There are many problems in operator theory, where most of the complexities and subtleties are present in the finite-dimensional case. My purpose in writing this book is to present a systematic treatment of methods that are useful in the study of such problems. This book is intended for use as a text for upper division and gradu­ ate courses. Courses based on parts of the material have been given by me at the Indian Statistical Institute and at the University of Toronto (in collaboration with Chandler Davis). The book should also be useful as a reference for research workers in linear algebra, operator theory, mathe­ matical physics and numerical analysis. A possible subtitle of this book could be Matrix Inequalities. A reader who works through the book should expect to become proficient in the art of deriving such inequalities. Other authors have compared this art to that of cutting diamonds. One first has to...

  1. Stabilization of a Network of the FitzHugh–Nagumo Oscillators by Means of a Single Capacitor Based RC Filter Feedback Technique

    Directory of Open Access Journals (Sweden)

    Elena Adomaitienė

    2017-01-01

    Full Text Available We suggest employing the first-order stable RC filters, based on a single capacitor, for control of unstable fixed points in an array of oscillators. A single capacitor is sufficient to stabilize an entire array, if the oscillators are coupled strongly enough. An array, composed of 24 to 30 mean-field coupled FitzHugh–Nagumo (FHN type asymmetric oscillators, is considered as a case study. The investigation has been performed using analytical, numerical, and experimental methods. The analytical study is based on the mean-field approach, characteristic equation for finding the eigenvalue spectrum, and the Routh–Hurwitz stability criteria using low-rank Hurwitz matrix to calculate the threshold value of the coupling coefficient. Experiments have been performed with a hardware electronic analog, imitating dynamical behavior of an array of the FHN oscillators.

  2. Phase change material thermal capacitor clothing

    Science.gov (United States)

    Buckley, Theresa M. (Inventor)

    2005-01-01

    An apparatus and method for metabolic cooling and insulation of a user in a cold environment. In its preferred embodiment the apparatus is a highly flexible composite material having a flexible matrix containing a phase change thermal storage material. The apparatus can be made to heat or cool the body or to act as a thermal buffer to protect the wearer from changing environmental conditions. The apparatus may also include an external thermal insulation layer and/or an internal thermal control layer to regulate the rate of heat exchange between the composite and the skin of the wearer. Other embodiments of the apparatus also provide 1) a path for evaporation or direct absorption of perspiration from the skin of the wearer for improved comfort and thermal control, 2) heat conductive pathways within the material for thermal equalization, 3) surface treatments for improved absorption or rejection of heat by the material, and 4) means for quickly regenerating the thermal storage capacity for reuse of the material. Applications of the composite materials are also described which take advantage of the composite's thermal characteristics. The examples described include a diver's wet suit, ski boot liners, thermal socks, gloves and a face mask for cold weather activities, and a metabolic heating or cooling blanket useful for treating hypothermia or fever patients in a medical setting and therapeutic heating or cooling orthopedic joint supports.

  3. Matrix pentagons

    Science.gov (United States)

    Belitsky, A. V.

    2017-10-01

    The Operator Product Expansion for null polygonal Wilson loop in planar maximally supersymmetric Yang-Mills theory runs systematically in terms of multi-particle pentagon transitions which encode the physics of excitations propagating on the color flux tube ending on the sides of the four-dimensional contour. Their dynamics was unraveled in the past several years and culminated in a complete description of pentagons as an exact function of the 't Hooft coupling. In this paper we provide a solution for the last building block in this program, the SU(4) matrix structure arising from internal symmetry indices of scalars and fermions. This is achieved by a recursive solution of the Mirror and Watson equations obeyed by the so-called singlet pentagons and fixing the form of the twisted component in their tensor decomposition. The non-singlet, or charged, pentagons are deduced from these by a limiting procedure.

  4. Matrix pentagons

    Directory of Open Access Journals (Sweden)

    A.V. Belitsky

    2017-10-01

    Full Text Available The Operator Product Expansion for null polygonal Wilson loop in planar maximally supersymmetric Yang–Mills theory runs systematically in terms of multi-particle pentagon transitions which encode the physics of excitations propagating on the color flux tube ending on the sides of the four-dimensional contour. Their dynamics was unraveled in the past several years and culminated in a complete description of pentagons as an exact function of the 't Hooft coupling. In this paper we provide a solution for the last building block in this program, the SU(4 matrix structure arising from internal symmetry indices of scalars and fermions. This is achieved by a recursive solution of the Mirror and Watson equations obeyed by the so-called singlet pentagons and fixing the form of the twisted component in their tensor decomposition. The non-singlet, or charged, pentagons are deduced from these by a limiting procedure.

  5. High energy storage capacitor by embedding tunneling nano-structures

    Science.gov (United States)

    Holme, Timothy P; Prinz, Friedrich B; Van Stockum, Philip B

    2014-11-04

    In an All-Electron Battery (AEB), inclusions embedded in an active region between two electrodes of a capacitor provide enhanced energy storage. Electrons can tunnel to/from and/or between the inclusions, thereby increasing the charge storage density relative to a conventional capacitor. One or more barrier layers is present in an AEB to block DC current flow through the device. The AEB effect can be enhanced by using multi-layer active regions having inclusion layers with the inclusions separated by spacer layers that don't have the inclusions. The use of cylindrical geometry or wrap around electrodes and/or barrier layers in a planar geometry can enhance the basic AEB effect. Other physical effects that can be employed in connection with the AEB effect are excited state energy storage, and formation of a Bose-Einstein condensate (BEC).

  6. Carbon activation process for increased surface accessibility in electrochemical capacitors

    Science.gov (United States)

    Doughty, Daniel H.; Eisenmann, Erhard T.

    2001-01-01

    A process for making carbon film or powder suitable for double capacitor electrodes having a capacitance of up to about 300 F/cm.sup.3 is disclosed. This is accomplished by treating in aqueous nitric acid for a period of about 5 to 15 minutes thin carbon films obtained by carbonizing carbon-containing polymeric material having a high degree of molecular directionality, such as polyimide film, then heating the treated carbon film in a non-oxidizing atmosphere at a non-graphitizing temperature of at least 350.degree. C. for about 20 minutes, and repeating alternately the nitric acid step and the heating step from 7 to 10 times. Capacitors made with this carbon may find uses ranging from electronic devices to electric vehicle applications.

  7. Neutron induced degradation in nitrided pyrogenic field oxide MOS capacitors

    CERN Document Server

    Vaidya, S J; Shaikh, A M; Chandorkar, A N

    2002-01-01

    Neutron induced oxide charge trapping and generation of interface states in MOS capacitors with pyrogenic and nitrided pyrogenic field oxides have been studied. In order to assess the damage due to neutrons alone, it is necessary to account for the damage produced by the accompanying gamma rays from neutron radiation. This is done by measuring the intensity of gamma radiation accompanying neutrons at different neutron fluences at the irradiation position. MOS capacitor structures were subjected to neutron radiation in a swimming pool type of reactor. Other samples from the same batch were then subjected to an equivalent dose of gamma radiation from a Co sup 6 sup 0 source. The difference in the damage observed was used to characterize the damage caused by neutrons. It is observed that neutrons, though uncharged, are capable of causing ionization damage. This damage is found to be significant when the radiation is performed under biased conditions. Nitridation in different ambients is found to improve the radi...

  8. A Wireless Implantable Switched-Capacitor Based Optogenetic Stimulating System

    Science.gov (United States)

    Lee, Hyung-Min; Kwon, Ki-Yong; Li, Wen

    2015-01-01

    This paper presents a power-efficient implantable optogenetic interface using a wireless switched-capacitor based stimulating (SCS) system. The SCS efficiently charges storage capacitors directly from an inductive link and periodically discharges them into an array of micro-LEDs, providing high instantaneous power without affecting wireless link and system supply voltage. A custom-designed computer interface in LabVIEW environment wirelessly controls stimulation parameters through the inductive link, and an optrode array enables simultaneous neural recording along with optical stimulation. The 4-channel SCS system prototype has been implemented in a 0.35-μm CMOS process and combined with the optrode array. In vivo experiments involving light-induced local field potentials verified the efficacy of the SCS system. An implantable version of the SCS system with flexible hermetic sealing is under development for chronic experiments. PMID:25570099

  9. Extracting renewable energy from a salinity difference using a capacitor.

    Science.gov (United States)

    Brogioli, Doriano

    2009-07-31

    Completely renewable energy can be produced by using water solutions of different salinity, like river water and sea water. Many different methods are already known, but development is still at prototype stage. Here I report a novel method, based on electric double-layer capacitor technology. Two porous electrodes, immersed in the salt solution, constitute a capacitor. It is first charged, then the salt solution is brought into contact with fresh water. The electrostatic energy increases as the salt concentration of the solution is reduced due to diffusion. This device can be used to turn sources of salinity difference into completely renewable sources of energy. An experimental demonstration is given, and performances and possible improvements are discussed.

  10. Carbon-Based Fibrous EDLC Capacitors and Supercapacitors

    Directory of Open Access Journals (Sweden)

    C. Lekakou

    2011-01-01

    Full Text Available This paper investigates electrochemical double-layer capacitors (EDLCs including two alternative types of carbon-based fibrous electrodes, a carbon fibre woven fabric (CWF and a multiwall carbon nanotube (CNT electrode, as well as hybrid CWF-CNT electrodes. Two types of separator membranes were also considered. An organic gel electrolyte PEO-LiCIO4-EC-THF was used to maintain a high working voltage. The capacitor cells were tested in cyclic voltammetry, charge-discharge, and impedance tests. The best separator was a glass fibre-fine pore filter. The carbon woven fabric electrode and the corresponding supercapacitor exhibited superior performance per unit area, whereas the multiwall carbon nanotube electrode and corresponding supercapacitor demonstrated excellent specific properties. The hybrid CWF-CNT electrodes did not show a combined improved performance due to the lack of carbon nanotube penetration into the carbon fibre fabric.

  11. Graphene oxide-based flexible metal–insulator–metal capacitors

    International Nuclear Information System (INIS)

    Bag, A; Hota, M K; Mallik, S; Maiti, C K

    2013-01-01

    This work explores the fabrication of graphene oxide (GO)-based metal–insulator–metal (MIM) capacitors on flexible polyethylene terephthalate (PET) substrates. Electrical properties are studied in detail. A high capacitance density of ∼4 fF µm −2 measured at 1 MHz and permittivity of ∼6 have been obtained. A low voltage coefficient of capacitance, VCC-α, and a low dielectric loss tangent indicate the potential of GO-based MIM capacitors for RF applications. The constant voltage stressing study has shown a high reliability against degradation up to a projected period of 10 years. Degradation in capacitance of the devices on flexible substrates has been studied by bending radius down to 1 cm even up to 6000 times of repeated bending. (paper)

  12. Permanent split capacitor single phase electric motor system

    Science.gov (United States)

    Kirschbaum, H.S.

    1984-08-14

    A permanent split capacitor single phase electric motor achieves balanced operation at more than one operating point by adjusting the voltage supplied to the main and auxiliary windings and adjusting the capacitance in the auxiliary winding circuit. An intermediate voltage tap on an autotransformer supplies voltage to the main winding for low speed operation while a capacitive voltage divider is used to adjust the voltage supplied to the auxiliary winding for low speed operation. 4 figs.

  13. Clad fiber capacitor and method of making same

    Science.gov (United States)

    Tuncer, Enis

    2012-12-11

    A clad capacitor and method of manufacture includes assembling a preform comprising a ductile, electrically conductive fiber; a ductile, electrically insulating cladding positioned on the fiber; and a ductile, electrically conductive sleeve positioned over the cladding. One or more preforms are then bundled, heated and drawn along a longitudinal axis to decrease the diameter of the ductile components of the preform and fuse the preform into a unitized strand.

  14. A review of molecular modelling of electric double layer capacitors.

    Science.gov (United States)

    Burt, Ryan; Birkett, Greg; Zhao, X S

    2014-04-14

    Electric double-layer capacitors are a family of electrochemical energy storage devices that offer a number of advantages, such as high power density and long cyclability. In recent years, research and development of electric double-layer capacitor technology has been growing rapidly, in response to the increasing demand for energy storage devices from emerging industries, such as hybrid and electric vehicles, renewable energy, and smart grid management. The past few years have witnessed a number of significant research breakthroughs in terms of novel electrodes, new electrolytes, and fabrication of devices, thanks to the discovery of innovative materials (e.g. graphene, carbide-derived carbon, and templated carbon) and the availability of advanced experimental and computational tools. However, some experimental observations could not be clearly understood and interpreted due to limitations of traditional theories, some of which were developed more than one hundred years ago. This has led to significant research efforts in computational simulation and modelling, aimed at developing new theories, or improving the existing ones to help interpret experimental results. This review article provides a summary of research progress in molecular modelling of the physical phenomena taking place in electric double-layer capacitors. An introduction to electric double-layer capacitors and their applications, alongside a brief description of electric double layer theories, is presented first. Second, molecular modelling of ion behaviours of various electrolytes interacting with electrodes under different conditions is reviewed. Finally, key conclusions and outlooks are given. Simulations on comparing electric double-layer structure at planar and porous electrode surfaces under equilibrium conditions have revealed significant structural differences between the two electrode types, and porous electrodes have been shown to store charge more efficiently. Accurate electrolyte and

  15. Electrochemical capacitor based on materials with pseudocapacitive properties

    OpenAIRE

    Olivia Moreno, David

    2011-01-01

    This thesis is divided into two chapters. Chapter 1 is about energy storage device such as the electrochemical capacitor (EC) and the electrode materials used for its construction. The basic principle of supercapacitor performance, double-layer capacitance and pseudocapacitance phenomena are described in the introduction. Activated carbons, nanotubes, conducting polymers and metal oxides as well as their composites were considered as electrode materials. Symmetric and asymmetric configurat...

  16. Comparison of topologies suitable for Capacitor Charging Systems

    CERN Document Server

    Maestri, S; Uicich, G; Benedetti, M; Cravero, JM

    2014-01-01

    This paper presents a comparison between topologies suitable for capacitor charging systems. The topologies under evaluation are a flyback converter, a half-bridge series resonant converter and a full-bridge phase-shifted converter. The main features of these topologies are highlighted, which allows the proper topology selection according to the application requirements. Moreover, the performed analysis permits to characterize the operational range of the main components thus allowing their appropriate sizing and selection. Simulation results are provided.

  17. Electromagnetic Compatibility of Matrix Converter System

    Directory of Open Access Journals (Sweden)

    S. Fligl

    2006-12-01

    Full Text Available The presented paper deals with matrix converters pulse width modulation strategies design with emphasis on the electromagnetic compatibility. Matrix converters provide an all-silicon solution to the problem of converting AC power from one frequency to another, offering almost all the features required of an ideal static frequency changer. They possess many advantages compared to the conventional voltage or current source inverters. A matrix converter does not require energy storage components as a bulky capacitor or an inductance in the DC-link, and enables the bi-directional power flow between the power supply and load. The most of the contemporary modulation strategies are able to provide practically sinusoidal waveforms of the input and output currents with negligible low order harmonics, and to control the input displacement factor. The perspective of matrix converters regarding EMC in comparison with other types of converters is brightly evident because it is no need to use any equipment for power factor correction and current and voltage harmonics reduction. Such converter with proper control is properly compatible both with the supply mains and with the supplied load. A special digital control system was developed for the realized experimental test bed which makes it possible to achieve greater throughput of the digital control system and its variability.

  18. Modulation of Molecular Flux Using a Graphene Nanopore Capacitor.

    Science.gov (United States)

    Shankla, Manish; Aksimentiev, Aleksei

    2017-04-20

    Modulation of ionic current flowing through nanoscale pores is one of the fundamental biological processes. Inspired by nature, nanopores in synthetic solid-state membranes are being developed to enable rapid analysis of biological macromolecules and to serve as elements of nanofludic circuits. Here, we theoretically investigate ion and water transport through a graphene-insulator-graphene membrane containing a single, electrolyte-filled nanopore. By means of all-atom molecular dynamics simulations, we show that the charge state of such a graphene nanopore capacitor can regulate both the selectivity and the magnitude of the nanopore ionic current. At a fixed transmembrane bias, the ionic current can be switched from being carried by an equal mixture of cations and anions to being carried almost exclusively by either cationic or anionic species, depending on the sign of the charge assigned to both plates of the capacitor. Assigning the plates of the capacitor opposite sign charges can either increase the nanopore current or reduce it substantially, depending on the polarity of the bias driving the transmembrane current. Facilitated by the changes of the nanopore surface charge, such ionic current modulations are found to occur despite the physical dimensions of the nanopore being an order of magnitude larger than the screening length of the electrolyte. The ionic current rectification is accompanied by a pronounced electro-osmotic effect that can transport neutral molecules such as proteins and drugs across the solid-state membrane and thereby serve as an interface between electronic and chemical signals.

  19. Random Vibration Testing of Advanced Wet Tantalum Capacitors

    Science.gov (United States)

    Teverovsky, Alexander

    2015-01-01

    Advanced wet tantalum capacitors allow for improved performance of power supply systems along with substantial reduction of size and weight of the systems that is especially beneficial for space electronics. Due to launch-related stresses, acceptance testing of all space systems includes random vibration test (RVT). However, many types of advanced wet tantalum capacitors cannot pass consistently RVT at conditions specified in MIL-PRF-39006, which impedes their use in space projects. This requires a closer look at the existing requirements, modes and mechanisms of failures, specifics of test conditions, and acceptance criteria. In this work, different lots of advanced wet tantalum capacitors from four manufacturers have been tested at step stress random vibration conditions while their currents were monitored before, during, and after the testing. It has been shown that the robustness of the parts and their reliability are mostly due to effective self-healing processes and limited current spiking or minor scintillations caused by RVT do not increase the risk of failures during operation. A simple model for scintillations events has been used to simulate current spiking during RVT and optimize test conditions. The significance of scintillations and possible effects of gas generation have been discussed and test acceptance criteria for limited current spiking have been suggested.

  20. Redox-capacitor to connect electrochemistry to redox-biology.

    Science.gov (United States)

    Kim, Eunkyoung; Leverage, W Taylor; Liu, Yi; White, Ian M; Bentley, William E; Payne, Gregory F

    2014-01-07

    It is well-established that redox-reactions are integral to biology for energy harvesting (oxidative phosphorylation), immune defense (oxidative burst) and drug metabolism (phase I reactions), yet there is emerging evidence that redox may play broader roles in biology (e.g., redox signaling). A critical challenge is the need for tools that can probe biologically-relevant redox interactions simply, rapidly and without the need for a comprehensive suite of analytical methods. We propose that electrochemistry may provide such a tool. In this tutorial review, we describe recent studies with a redox-capacitor film that can serve as a bio-electrode interface that can accept, store and donate electrons from mediators commonly used in electrochemistry and also in biology. Specifically, we (i) describe the fabrication of this redox-capacitor from catechols and the polysaccharide chitosan, (ii) discuss the mechanistic basis for electron exchange, (iii) illustrate the properties of this redox-capacitor and its capabilities for promoting redox-communication between biology and electrodes, and (iv) suggest the potential for enlisting signal processing strategies to "extract" redox information. We believe these initial studies indicate broad possibilities for enlisting electrochemistry and signal processing to acquire "systems level" redox information from biology.

  1. The influence of capacitor banks on transformer load current

    Directory of Open Access Journals (Sweden)

    Jović Aleksandar S.

    2017-01-01

    Full Text Available This paper deals with the influence of capacitor banks used for reactive energy compensation on total load current of 10/0,4 kV/kV distribution transformers. The analysis regards distribution area of Leskovac which comprehends town Leskovac and nearby settlements. Differently from previously published references that treat excessively reactive energy consumption, the value of reactive power on low voltage side of transformer taking into account the presence of capacitor banks is observed primarily in this paper. Both theoretically possible cases are restated on the basis of measurements: the compensation is adequate or inadequate. The cases of insufficient compensation and overcompensation are regarded to be inadequate compensation. The adequate compensation is achieved when reactive power oscillates around 0 kvar. The special case of adequate compensation, called conditionally adequate compensation, is introduced. For all four cases that describe reactive energy compensation, the calculation results of relative change of low voltage transformer current in the presence of capacitor banks, in comparison to the current without installed banks are presented.

  2. Electric converters of electromagnetic strike machine with capacitor supply

    Science.gov (United States)

    Usanov, K. M.; Volgin, A. V.; Kargin, V. A.; Moiseev, A. P.; Chetverikov, E. A.

    2018-03-01

    The application of pulse linear electromagnetic engines in small power strike machines (energy impact is 0.01...1.0 kJ), where the characteristic mode of rare beats (pulse seismic vibrator, the arch crash device bins bulk materials), is quite effective. At the same time, the technical and economic performance of such machines is largely determined by the ability of the power source to provide a large instantaneous power of the supply pulses in the winding of the linear electromagnetic motor. The use of intermediate energy storage devices in power systems of rare-shock LEME makes it possible to obtain easily large instantaneous powers, forced energy conversion, and increase the performance of the machine. A capacitor power supply of a pulsed source of seismic waves is proposed for the exploration of shallow depths. The sections of the capacitor storage (CS) are connected to the winding of the linear electromagnetic motor by thyristor dischargers, the sequence of activation of which is determined by the control device. The charge of the capacitors to the required voltage is made directly from the battery source, or through the converter from a battery source with a smaller number of batteries.

  3. Chemical modification of graphene aerogels for electrochemical capacitor applications.

    Science.gov (United States)

    Hong, Jin-Yong; Wie, Jeong Jae; Xu, Yu; Park, Ho Seok

    2015-12-14

    Graphene aerogel is a relatively new type of aerogel that is ideal for energy storage applications because of its large surface area, high electrical conductivity and good chemical stability. Also, three dimensional interconnected macropores offer many advantages such as low density, fast ion and mass transfer, and easy access to storage sites. Such features allow graphene aerogels to be intensively applied for electrochemical capacitor applications. Despite the growing interest in graphene aerogel-based electrochemical capacitors, however, the graphene aerogels still suffer from their low capacitive performances and high fragility. Both relatively low capacitance and brittleness of physically crosslinked graphene aerogels remain a critical challenge. Until now, a number of alternative attempts have been devoted to overcome these shortcomings. In this perspective, we summarize the recent research progress towards the development of advanced graphene aerogel-based electrochemical capacitors according to the different approaches (e.g. porosity, composition and structure controls). Then, the recently proposed chemical strategies to improve the capacitive performances and mechanical durability of graphene aerogels for practical applications are highlighted. Finally, the current challenges and perspectives in this emerging material are also discussed.

  4. 50V All-PMOS Charge Pumps Using Low-Voltage Capacitors

    KAUST Repository

    Emira, Ahmed

    2012-10-06

    In this work, two high-voltage charge pumps are introduced. In order to minimize the area of the pumping capacitors, which dominates the overall area of the charge pump, high density capacitors have been utilized. Nonetheless, these high density capacitors suffer from low breakdown voltage which is not compatible with the targeted high voltage application. To circumvent the breakdown limitation, a special clocking scheme is used to limit the maximum voltage across any pumping capacitor. The two charge pump circuits were fabricated in a 0:6m CMOS technology with poly0-poly1 capacitors. The output voltage of the two charge pumps reached 42:8V and 51V while the voltage across any capacitor did not exceed the value of the input voltage. Compared to other designs reported in the literature, the proposed charge pump provides the highest output voltage which makes it more suitable for tuning MEMS devices.

  5. Leakage Currents in Low-Voltage PME and BME Ceramic Capacitors

    Science.gov (United States)

    Teverovsky, Alexander

    2015-01-01

    Introduction of BME capacitors to high-reliability electronics as a replacement for PME capacitors requires better understanding of changes in performance and reliability of MLCCs to set justified screening and qualification requirements. In this work, absorption and leakage currents in various lots of commercial and military grade X7R MLCCs rated to 100V and less have been measured to reveal difference in behavior of PME and BME capacitors in a wide range of voltages and temperatures. Degradation of leakage currents and failures in virgin capacitors and capacitors with introduced cracks has been studied at different voltages and temperatures during step stress highly accelerated life testing. Mechanisms of charge absorption, conduction and degradation have been discussed and a failure model in capacitors with defects suggested.

  6. A Humidity-Dependent Lifetime Derating Factor for DC Film Capacitors

    DEFF Research Database (Denmark)

    Wang, Huai; Reigosa, Paula Diaz; Blaabjerg, Frede

    2015-01-01

    accelerated testing of film capacitors under different humidity conditions, enabling a more justified lifetime prediction of film capacitors for DC-link applications under specific climatic environments. The analysis of the testing results and the detailed discussion on the derating factor with different......Film capacitors are widely assumed to have superior reliability performance than Aluminum electrolytic capacitors in DC-link design of power electronic converters. However, the assumption needs to be critically judged especially for applications under high humidity environments. This paper proposes...... a humidity-dependent lifetime derating factor for a type of plastic-boxed metallized DC film capacitors. It overcomes the limitation that the humidity impact is not considered in the state-of-the-art DC film capacitor lifetime models. The lifetime derating factor is obtained based on a total of 8,700 hours...

  7. 50V All-PMOS Charge Pumps Using Low-Voltage Capacitors

    KAUST Repository

    Emira, Ahmed; AbdelGhany, M.; Elsayed, M.; Elshurafa, Amro M.; Sedky, S.; Salama, Khaled N.

    2012-01-01

    In this work, two high-voltage charge pumps are introduced. In order to minimize the area of the pumping capacitors, which dominates the overall area of the charge pump, high density capacitors have been utilized. Nonetheless, these high density capacitors suffer from low breakdown voltage which is not compatible with the targeted high voltage application. To circumvent the breakdown limitation, a special clocking scheme is used to limit the maximum voltage across any pumping capacitor. The two charge pump circuits were fabricated in a 0:6m CMOS technology with poly0-poly1 capacitors. The output voltage of the two charge pumps reached 42:8V and 51V while the voltage across any capacitor did not exceed the value of the input voltage. Compared to other designs reported in the literature, the proposed charge pump provides the highest output voltage which makes it more suitable for tuning MEMS devices.

  8. An Active Capacitor with Self-Power and Internal Feedback Control Signals

    DEFF Research Database (Denmark)

    Wang, Haoran; Wang, Huai

    2017-01-01

    This paper proposes a concept of two-terminal active capacitor implemented by power semiconductor switches and passive elements. The active capacitor has the same level of convenience as a passive one with two power terminals only. A control strategy that does not require any external feedback...... signal is proposed and a self-power scheme for gate drivers and the controller is applied to achieve the two-terminal active capacitor. The concept, control method, self-power scheme, efficiency, and impedance characteristics of the active capacitor are presented. A case study of the proposed active...... capacitor for a capacitive DC-link application is discussed. The results reveal a significantly lower overall energy storage of passive elements and a reduced cost to fulfill a specific reliability target, compared to a passive capacitor solution. Proof-of-concept experimental results are given to verify...

  9. A Robust DC-Split-Capacitor Power Decoupling Scheme for Single-Phase Converter

    DEFF Research Database (Denmark)

    Yao, Wenli; Loh, Poh Chiang; Tang, Yi

    2017-01-01

    Instead of bulky electrolytic capacitors, active power decoupling circuit can be introduced to a single-phase converter for diverting second harmonic ripple away from its dc source or load. One possible circuit consists of a half-bridge and two capacitors in series for forming a dc-split capacitor......, instead of the usual single dc-link capacitor bank. Methods for regulating this power decoupler have earlier been developed, but almost always with equal capacitances assumed for forming the dc-split capacitor, even though it is not realistic in practice. The assumption should, hence, be evaluated more...... thoroughly, especially when it is shown in the paper that even a slight mismatch can render the power decoupling scheme ineffective and the IEEE 1547 standard to be breached. A more robust compensation scheme is, thus, needed for the dc-split capacitor circuit, as proposed and tested experimentally...

  10. High voltage capacitor design and the determination of solid dielectric voltage breakdown

    International Nuclear Information System (INIS)

    Hutapea, S.

    1976-01-01

    The value of the external field intensity serves as an electrical insulating material and is a physical characteristic of the substance. Capacitor discharge in the dielectric medium are experimentally investigated. The high voltage power supply and other instrument needed are briefly discussed. Capacitors with working voltage of 30.000 volt and the plastic being used for dielectrics in the capacitors are also discussed. (author)

  11. Neural network for optimal capacitor placement and its impact on power quality in electric distribution systems

    International Nuclear Information System (INIS)

    Mohamed, A.A.E.S.

    2013-01-01

    Capacitors are widely installed in distribution systems for reactive power compensation to achieve power and energy loss reduction, voltage regulation and system capacity release. The extent of these benefits depends greatly on how the capacitors are placed on the system. The problem of how to place capacitors on the system such that these benefits are achieved and maximized against the cost associated with the capacitor placement is termed the general capacitor placement problem. The capacitor placement problem has been formulated as the maximization of the savings resulted from reduction in both peak power and energy losses considering capacitor installation cost and maintaining the buses voltage within acceptable limits. After an appropriate analysis, the optimization problem was formulated in a quadratic form. For solving capacitor placement a new combinatorial heuristic and quadratic programming technique has been presented and applied in the MATLAB software. The proposed strategy was applied on two different radial distribution feeders. The results have been compared with previous works. The comparison showed the validity and the effectiveness of this strategy. Secondly, two artificial intelligence techniques for predicting the capacitor switching state in radial distribution feeders have been investigated; one is based on basis Radial Basis Neural Network (RBNN) and the other is based on Adaptive Neuro-Fuzzy Inference System (ANFIS). The ANFIS technique gives better results with a minimum total error compared to RBNN. The learning duration of ANFIS was very short than the neural network case. It implied that ANFIS reaches to the target faster than neural network. Thirdly, an artificial intelligence (RBNN) approach for estimation of transient overvoltage during capacitor switching has been studied. The artificial intelligence approach estimated the transient overvoltages with a minimum error in a short computational time. Finally, a capacitor switching

  12. Investigation on Capacitor Switching Transient Limiter with a Three phase Variable Resistance

    DEFF Research Database (Denmark)

    Naderi, Seyed Behzad; Jafari, Mehdi; Zandnia, Amir

    2017-01-01

    In this paper, a capacitor switching transient limiter based on a three phase variable resistance is proposed. The proposed structure eliminates the capacitor switching transient current and over-voltage by introducing a variable resistance to the current path with its special switching pattern...... transients on capacitor after bypassing. Analytic Analyses for this structure in transient cases are presented in details and simulations are performed by MATLAB software to prove its effectiveness....

  13. Incorporation of distributed generation and shunt capacitor in radial distribution system for techno-economic benefits

    Directory of Open Access Journals (Sweden)

    Mukul Dixit

    2017-04-01

    The various costs such as purchase active power from grid, DG installation, capacitor installation, DG Operation and Maintenance (O&M are evaluated at two different load scenarios. In addition to that, technical and economical analyses are examined for various combinations of DGs and shunt capacitors. The proposed methodology is successfully demonstrated on 33-bus and 85-bus radial networks and the obtained numerical outcomes validate the suitability, importance and effectiveness to identify locations as well as sizes of DGs and shunt capacitors.

  14. Effect of capacitor loss on discharging characteristics of xenon flash lamp

    International Nuclear Information System (INIS)

    Zhang Chu; Lin Dejiang; Xu Chunmei; Shen Hongbin; Chen Xiaohan

    2012-01-01

    The effect of storage capacitor's loss on the discharging characteristics of the xenon flash lamp was studied, and the xenon flash lamp discharging circuit was analyzed and improved. The capacitor can be equivalent to a series of an ideal capacitor and loss resistance. The improved formula of the xenon lamp discharging characteristics was given when actual capacitance loss is not zero, and the xenon lamp discharging current and discharging power are calculated and analyzed in detail with the increase of the capacitor loss. The results show that the increase of loss will lead to the decrease of xenon lamp discharging current and peak power and the xenon lamp flash time, and influence laser pumping efficiency. The loss will also lead to the capacitor inverse charging in LC discharging circuit; this will influence normal working of the capacitor and decrease the lift of the xenon lamp. The actual energy storage capacitor charging and discharging experiments show that the increase of capacitor loss will lead to the decrease of xenon lamp light-emitting waveform peak, shortening of the flash time and increase of the electrode sputter, thus verity, the reasonableness of theoretical analysis. In addition, the experiments show that environmental factors have very significant impact on the increase of the storage capacitor loss. (authors)

  15. A Novel Flying Capacitor Transformerless Inverter for Single-Phase Grid Connected Solar Photovoltaic System

    DEFF Research Database (Denmark)

    Siwakoti, Yam Prasad; Blaabjerg, Frede

    2016-01-01

    This paper proposes a new single-phase flying capacitor transformerless PV inverter for grid-connected photovoltaic (PV) systems. The neutral of the grid can be directly connected to the negative terminal of the source (PV). It consists of four power switches, one diode, one capacitor and a small...... and some topologies, which requires two times of the peak ac-voltage magnitude) and, (5) the flying capacitor charges every switching cycle, which reduces the size of the required capacitor with switching frequency. In addition, industry standard half bridge module can be used in the new inverter without...

  16. Enhanced DC-Link Capacitor Voltage Balancing Control of DC–AC Multilevel Multileg Converters

    DEFF Research Database (Denmark)

    Busquets-Monge, Sergio; Maheshwari, Ram Krishan; Nicolas-Apruzzese, Joan

    2015-01-01

    This paper presents a capacitor voltage balancing control applicable to any multilevel dc–ac converter formed by a single set of series-connected capacitors implementing the dc link and semiconductor devices, such as the diode-clamped topology. The control is defined for any number of dc-link vol......This paper presents a capacitor voltage balancing control applicable to any multilevel dc–ac converter formed by a single set of series-connected capacitors implementing the dc link and semiconductor devices, such as the diode-clamped topology. The control is defined for any number of dc...

  17. Design of constant current charging power supply for J-TEXT ohmic field capacitor banks

    International Nuclear Information System (INIS)

    Lv Shudong; Zhang Ming; Rao Bo; Yu Kexun; Yang Cheng

    2014-01-01

    The charging characteristic of the capacitor charging power supply was analyzed with practical series resonant topology. The method that setting two current taps and regulating PWM switching frequency was putted forward with close loop controlling algorithm to charge the multi-group capacitor banks with constant current. A capacitor charging power supply with the max output current 6.5 A and the max output voltage 2000 V is designed. Experimental results show that, this power supply can charge the four capacitor banks to any four different voltages in 1 minute with charging accuracy less than 1%, and meet the requirements of J-TEXT ohmic field power system. (authors)

  18. Evaluation of gamma radiation response of electrolyte, MKP and MKT capacitors in various frequencies

    International Nuclear Information System (INIS)

    Malekie, Shahryar; Salehpour, Behrooz

    2017-01-01

    In this experimental work, the effect of gamma irradiation on the capacitance and impedance of some commercial capacitors namely electrolytic, MKP, and MKT capacitors in different radiation doses up to 120 kGy and a wide range of frequencies between 42 Hz and 5 MHz were studied. Results showed that the capacitances of the electrolytic capacitors exhibited a linear decrease by increasing the radiation dose and frequencies, which can be used for high dosimetry purposes, but non-ceramic capacitors as MKP and MKT showed much higher radiation resistance, particularly for the frequencies less than ∝1 MHz.

  19. A Power-Efficient Wireless Capacitor Charging System Through an Inductive Link.

    Science.gov (United States)

    Lee, Hyung-Min; Ghovanloo, Maysam

    2013-10-01

    A power-efficient wireless capacitor charging system for inductively powered applications has been presented. A bank of capacitors can be directly charged from an ac source by generating a current through a series charge injection capacitor and a capacitor charger circuit. The fixed charging current reduces energy loss in switches, while maximizing the charging efficiency. An adaptive capacitor tuner compensates for the resonant capacitance variations during charging to keep the amplitude of the ac input voltage at its peak. We have fabricated the capacitor charging system prototype in a 0.35- μ m 4-metal 2-poly standard CMOS process in 2.1 mm 2 of chip area. It can charge four pairs of capacitors sequentially. While receiving 2.7-V peak ac input through a 2-MHz inductive link, the capacitor charging system can charge each pair of 1 μ F capacitors up to ±2 V in 420 μ s, achieving a high measured charging efficiency of 82%.

  20. Evaluation of gamma radiation response of electrolyte, MKP and MKT capacitors in various frequencies

    Energy Technology Data Exchange (ETDEWEB)

    Malekie, Shahryar [Nuclear Science and Technology Research Institute, Karaj (Iran, Islamic Republic of). Radiation Application Research School; Salehpour, Behrooz [Tabriz Univ. (Iran, Islamic Republic of). Faculty of Physics

    2017-09-01

    In this experimental work, the effect of gamma irradiation on the capacitance and impedance of some commercial capacitors namely electrolytic, MKP, and MKT capacitors in different radiation doses up to 120 kGy and a wide range of frequencies between 42 Hz and 5 MHz were studied. Results showed that the capacitances of the electrolytic capacitors exhibited a linear decrease by increasing the radiation dose and frequencies, which can be used for high dosimetry purposes, but non-ceramic capacitors as MKP and MKT showed much higher radiation resistance, particularly for the frequencies less than ∝1 MHz.

  1. Device for detecting imminent failure of high-dielectric stress capacitors. [Patent application

    Science.gov (United States)

    McDuff, G.G.

    1980-11-05

    A device is described for detecting imminent failure of a high-dielectric stress capacitor utilizing circuitry for detecting pulse width variations and pulse magnitude variations. Inexpensive microprocessor circuitry is utilized to make numerical calculations of digital data supplied by detection circuitry for comparison of pulse width data and magnitude data to determine if preselected ranges have been exceeded, thereby indicating imminent failure of a capacitor. Detection circuitry may be incorporated in transmission lines, pulse power circuitry, including laser pulse circuitry or any circuitry where capacitors or capacitor banks are utilized.

  2. Digital Realization of Capacitor-Voltage Feedback Active Damping for LCL-Filtered Grid Converters

    DEFF Research Database (Denmark)

    Xin, Zhen; Wang, Xiongfei; Loh, Poh Chiang

    2015-01-01

    The capacitor voltage of an LCL-filter can also be used for active damping, if it is fed back for synchronization. By this way, an extra current sensor can be avoided. Compared with the existing active damping techniques designed with capacitor current feedback, the capacitor voltage feedback....... To overcome their drawbacks, a new derivative method is then proposed, based on the non-ideal generalized integrator. The performance of the proposed derivative has been found to match the ideal “s” function closely. Active damping based on capacitor voltage feedback can therefore be realized accurately...

  3. Capacitor Mismatch Error Cancellation Technique for a Successive Approximation A/D Converter

    DEFF Research Database (Denmark)

    Zheng, Zhiliang; Moon, Un-Ku; Steensgaard-Madsen, Jesper

    1999-01-01

    An error cancellation technique is described for suppressing capacitor mismatch in a successive approximation A/D converter. At the cost of a 50% increase in conversion time, the first-order capacitor mismatch error is cancelled. Methods for achieving top-plate parasitic insensitive operation...... are described, and the use of a gain- and offset-compensated opamp is explained. SWITCAP simulation results show that the proposed 16-bit SAR ADC can achieve an SNDR of over 91 dB under non-ideal conditions, including 1% 3 sigma nominal capacitor mismatch, 10-20% randomized parasitic capacitors, 66 dB opamp...

  4. Capacitor voltage ripple reduction and arm energy balancing in MMC-HVDC

    DEFF Research Database (Denmark)

    Parikh, Harsh; Martin-Loeches, Ruben Sánches; Tsolaridis, Georgios

    2016-01-01

    Modular Multilevel Converters are emerging and widely used in HVDC applications. However, the submodule capacitors are still large and the energy balancing under unbalanced conditions is a challenge. In this paper, an analytical model focusing on the energy stored in the capacitors and voltage...... variations is utilized in order to achieve better performance. By injecting a second order harmonic component into the circulating current, the energy variation and consequently the capacitor voltage ripple is reduced allowing for a capacitor size reduction. At the same time, an arm energy balancing...

  5. Electro-mechanical properties of free standing micro- and nano-scale polymer-ceramic composites for energy density capacitors

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Paritosh; Borkar, Hitesh [CSIR-National Physical Laboratory, Dr. K. S. Krishnan Marg, New Delhi, 110012 (India); Academy of Scientific and Innovative Research (AcSIR), CSIR-National Physical Laboratory (CSIR-NPL) Campus, Dr. K. S. Krishnan Road, New Delhi, 110012 (India); Singh, B.P.; Singh, V.N. [CSIR-National Physical Laboratory, Dr. K. S. Krishnan Marg, New Delhi, 110012 (India); Kumar, Ashok, E-mail: ashok553@nplindia.org [CSIR-National Physical Laboratory, Dr. K. S. Krishnan Marg, New Delhi, 110012 (India); Academy of Scientific and Innovative Research (AcSIR), CSIR-National Physical Laboratory (CSIR-NPL) Campus, Dr. K. S. Krishnan Road, New Delhi, 110012 (India)

    2015-11-05

    The integration of inorganic fillers in polymer matrix is useful for superior mechanical strength and functional properties of polymer-ceramic composites. We report the fabrication and characterization of polyvinylidene fluoride-CoFe{sub 2}O{sub 4} (PVDF-CFO) (wt% 80:20, respectively) and PVDF-Pb(Zr{sub 0.52}Ti{sub 0.48})O{sub 3}–CoFe{sub 2}O{sub 4} (PVDF-PZT-CFO) (wt% 80:10:10, respectively) free standing 50 μm thick ferroelectric-polymer-ceramic composites films. X-ray diffraction (XRD) patterns and Raman spectra revealed the presence of major semi-crystalline β-PVDF along with α-phase which is responsible for ferroelectric nature in both the composite systems. Ferroelectric, dielectric and mechanical strength measurements were performed in order to evaluate the effects of CFO and PZT inorganic fillers in PVDF matrix. The inclusion of CFO and PZT micro-/nano-particles in PVDF polymer matrix improved the polarization behavior, dielectric properties and mechanical strength. The energy density was calculated by polarization-electric field hysteresis loop and found in the range of 6–8 J/cm{sup 3} may be useful for microelectronics. - Graphical abstract: Large area PVDF-PZT-CFO nano- and micro-composite films have been fabricated for high energy density storage flexible capacitor. Presence of nanocrystalline PZT and CFO particles in polymer matrix significantly enhanced their energy density capacity. - Highlights: • Physical interaction of cobalt iron oxide with polymer matrix results β-PVDF phase. • Evidence of Micro and Nano crystalline CFO and PZT fillers in polymer matrix. • The CFO and PZT fillers provide better mechanical strength to composite films. • PVDF-ceramic nanocomposites show low leakage behavior for high electric field.

  6. Electrically and thermally activated ageing mechanisms in metallised polymer film capacitors

    International Nuclear Information System (INIS)

    Lee, Yuen Pen

    2001-01-01

    This dissertation describes a combined computational and experimental study to understand the fundamental electrostatic, thermal, electromagnetic, and discharge related processes during the ageing of metallised polymer film capacitors. In the event of internal breakdowns, these capacitors are capable of 'self-healing' through a controlled isolation of defects on the electrode surfaces by mosaic patterning the electrode. The objective of this project is to develop viable computer models to unravel electrothermally activated ageing processes in capacitors. To provide the necessary validation to any capacitor models developed, our work is supported by comprehensive experiments including industrial standard accelerated life tests and associated breakdown damage analyses of tested capacitors. These have enabled an empirical identification of main factors affecting the reliability and lifetime of capacitors. Relevant raw data and the qualitative picture enabled by these data are crucial to the development and refinement of viable computational models of capacitors. Given the complexity of ageing processes, it is both very difficult and unnecessary to develop a one-for-all model that describes indiscriminately all relevant processes. The approach adapted in this work has been to prioritise key ageing processes and modularise each process with its own computer model. The overall picture of capacitor ageing can then be unravelled by integrating all modules together. For instance, the fine geometrical features of the electrode mosaic pattern and the capacitor's laminated structure have been assessed through a concept of field intensification using a 2D electrostatic finite element computation. With fine geometrical features accounted for by the field intensification concept, fast electric events in capacitors can be simulated using a simple equivalent circuit model. Similar assessment of heat transfer has led to an equally efficient modelling of thermal events in capacitors

  7. Anti-Ferroelectric Ceramics for High Energy Density Capacitors

    Directory of Open Access Journals (Sweden)

    Aditya Chauhan

    2015-11-01

    Full Text Available With an ever increasing dependence on electrical energy for powering modern equipment and electronics, research is focused on the development of efficient methods for the generation, storage and distribution of electrical power. In this regard, the development of suitable dielectric based solid-state capacitors will play a key role in revolutionizing modern day electronic and electrical devices. Among the popular dielectric materials, anti-ferroelectrics (AFE display evidence of being a strong contender for future ceramic capacitors. AFE materials possess low dielectric loss, low coercive field, low remnant polarization, high energy density, high material efficiency, and fast discharge rates; all of these characteristics makes AFE materials a lucrative research direction. However, despite the evident advantages, there have only been limited attempts to develop this area. This article attempts to provide a focus to this area by presenting a timely review on the topic, on the relevant scientific advancements that have been made with respect to utilization and development of anti-ferroelectric materials for electric energy storage applications. The article begins with a general introduction discussing the need for high energy density capacitors, the present solutions being used to address this problem, and a brief discussion of various advantages of anti-ferroelectric materials for high energy storage applications. This is followed by a general description of anti-ferroelectricity and important anti-ferroelectric materials. The remainder of the paper is divided into two subsections, the first of which presents various physical routes for enhancing the energy storage density while the latter section describes chemical routes for enhanced storage density. This is followed by conclusions and future prospects and challenges which need to be addressed in this particular field.

  8. High energy density capacitors fabricated by thin film technology

    International Nuclear Information System (INIS)

    Barbee, T W; Johnson, G W; Wagner, A V.

    1999-01-01

    Low energy density in conventional capacitors severely limits efforts to miniaturize power electronics and imposes design limitations on electronics in general. We have successfully applied physical vapor deposition technology to greatly increase capacitor energy density. The high dielectric breakdown strength we have achieved in alumina thin films allows high energy density to be achieved with this moderately low dielectric constant material. The small temperature dependence of the dielectric constant, and the high reliability, high resistivity, and low dielectric loss of Al 2 O 3 , make it even more appealing. We have constructed single dielectric layer thin film capacitors and shown that they can be stacked to form multilayered structures with no loss in yield for a given capacitance. Control of film growth morphology is critical for achieving the smooth, high quality interfaces between metal and dielectric necessary for device operation at high electric fields. Most importantly, high rate deposition with extremely low particle generation is essential for achieving high energy storage at a reasonable cost. This has been achieved by reactive magnetron sputtering in which the reaction to form the dielectric oxide has been confined to the deposition surface. By this technique we have achieved a yield of over 50% for 1 cm 2 devices with an energy density of 14 J per cubic centimeter of Al 2 O 3 dielectric material in 1.2 kV, 4 nF devices. By further reducing defect density and increasing the dielectric constant of the material, we will be able to increase capacitance and construct high energy density devices to meet the requirements of applications in power electronics

  9. Repetitively pulsed capacitor bank for the dense-plasma focus

    International Nuclear Information System (INIS)

    Zucker, O.; Bostick, W.; Gullickson, R.; Long, J.; Luce, J.; Sahlin, H.

    1975-12-01

    This report describes a 1 pulse per second capacitor bank designed to energize a dense-plasma focus (DPF). The DPF is a neutron source capable (with moderate scaling) of delivering a minimum of 10 15 neutrons per pulse or neutron flux of 2 x 10 13 N/cm 2 .s. The average power consumption, which has become a major issue due to the energy crisis, is analyzed with respect to other plasma devices and is shown to be highly favorable. This small source size high flux neutron source could be extemely useful to qualify fission reactor material irradiation results for fusion reactor design

  10. Current Control of Grid Converters Connected with Series AC Capacitor

    DEFF Research Database (Denmark)

    Wang, Xiongfei; Blaabjerg, Frede; Loh, Poh Chiang

    2015-01-01

    The series ac capacitor has recently been used with the transformerless grid-connected converters in the distribution power grids. The capacitive characteristic of the resulting series LC filter restricts the use of conventional synchronous integral or stationary resonant current controllers. Thus...... this paper proposes a fourth-order resonant controller in the stationary frame, which guarantees a zero steady-state current tracking error for the grid converters with series LC filter. This method is then implemented in a three-phase experimental system for verification, where the current harmonics below...... the LC filter resonance frequency are effectively eliminated. Experimental results confirm the validity of the proposed current control scheme....

  11. The quantum to classical crossover for a weak link capacitor

    International Nuclear Information System (INIS)

    Spiller, T.P.; Clark, T.D.; Prance, H.; Prance, R.J.

    1995-01-01

    We consider a model weak link, an ultra-small capacitor subject to tunnelling, to ohmic dissipation and fed with an external displacement current. The framework we employ is the new approach of quantum state diffusion, which treats individual open quantum systems as well as being able to generate the conventional ensemble averages. We show how evidence, for archetypal quantum behaviour (coherent oscillations) and archetypal classical behaviour (chaos) arises, for weak links whose parameters are related by a rather modest scaling. Interestingly, the quantum behaviour can arise for a weak link with intrinsic parameter values such that it could exhibit chaos, if it were a purely classical device

  12. Neural Implants, Packaging for Biocompatible Implants, and Improving Fabricated Capacitors

    Science.gov (United States)

    Agger, Elizabeth Rose

    We have completed the circuit design and packaging procedure for an NIH-funded neural implant, called a MOTE (Microscale Optoelectronically Transduced Electrode). Neural recording implants for mice have greatly advanced neuroscience, but they are often damaging and limited in their recording location. This project will result in free-floating implants that cause less damage, provide rapid electronic recording, and increase range of recording across the cortex. A low-power silicon IC containing amplification and digitization sub-circuits is powered by a dual-function gallium arsenide photovoltaic and LED. Through thin film deposition, photolithography, and chemical and physical etching, the Molnar Group and the McEuen Group (Applied and Engineering Physics department) will package the IC and LED into a biocompatible implant approximately 100microm3. The IC and LED are complete and we have begun refining this packaging procedure in the Cornell NanoScale Science & Technology Facility. ICs with 3D time-resolved imaging capabilities can image microorganisms and other biological samples given proper packaging. A portable, flat, easily manufactured package would enable scientists to place biological samples on slides directly above the Molnar group's imaging chip. We have developed a packaging procedure using laser cutting, photolithography, epoxies, and metal deposition. Using a flip-chip method, we verified the process by aligning and adhering a sample chip to a holder wafer. In the CNF, we have worked on a long-term metal-insulator-metal (MIM) capacitor characterization project. Former Fellow and continuing CNF user Kwame Amponsah developed the original procedure for the capacitor fabrication, and another former fellow, Jonilyn Longenecker, revised the procedure and began the arduous process of characterization. MIM caps are useful to clean room users as testing devices to verify electronic characteristics of their active circuitry. This project's objective is to

  13. Electric drive systems including smoothing capacitor cooling devices and systems

    Energy Technology Data Exchange (ETDEWEB)

    Dede, Ercan Mehmet; Zhou, Feng

    2017-02-28

    An electric drive system includes a smoothing capacitor including at least one terminal, a bus bar electrically coupled to the at least one terminal, a thermoelectric device including a first side and a second side positioned opposite the first side, where the first side is thermally coupled to at least one of the at least one terminal and the bus bar, and a cooling element thermally coupled to the second side of the thermoelectric device, where the cooling element dissipates heat from the thermoelectric device.

  14. Electronic inverter assembly with an integral snubber capacitor

    Science.gov (United States)

    Singh, Brij N.; Schmit, Christopher J.

    2017-08-01

    A coaxial bus connector has a first end and a second end opposite the first end. The first end has a first positive terminal and a first negative terminal coupled to a primary direct current bus of a primary inverter. The second end has a second positive terminal and a second negative terminal coupled to the secondary direct current bus of a secondary inverter, wherein the coaxial bus connector comprises a dielectric material between a center conductor and a coaxial sleeve to form a snubber capacitor to absorb electrical energy or to absorb voltage spikes.

  15. High speed capacitor-inverter based carbon nanotube full adder.

    Science.gov (United States)

    Navi, K; Rashtian, M; Khatir, A; Keshavarzian, P; Hashemipour, O

    2010-03-18

    Carbon Nanotube filed-effect transistor (CNFET) is one of the promising alternatives to the MOS transistors. The geometry-dependent threshold voltage is one of the CNFET characteristics, which is used in the proposed Full Adder cell. In this paper, we present a high speed Full Adder cell using CNFETs based on majority-not (Minority) function. Presented design uses eight transistors and eight capacitors. Simulation results show significant improvement in terms of delay and power-delay product in comparison to contemporary CNFET Adder Cells. Simulations were carried out using HSPICE based on CNFET model with 0.6 V VDD.

  16. THE DIAGNOSIS TECHNIQUE OF ABNORMAL HEATING OF POWER CAPACITORS

    Directory of Open Access Journals (Sweden)

    D. I. Zalizny

    2016-01-01

    Full Text Available The existing system of protection and diagnostics are not able to detect abnormal heating of the power capacitors caused by its internal malfunction formation. The paper contains a proposal of a technique that enables to detect such heat at its early study. This technique consists of a hardware and an algorithms. The hardware consists of a microprocessor-based instrument developed by the author, of measuring transformers of current and of temperature sensors. This equipment must be connected to the condenser unit with a rated voltage of 380 V. In operation, the device performs continuous measurement of the surface temperature of the casing of each condenser, the temperature of the external environment, voltage and current from the power source. The measured values are used in the mathematical model of thermal processes that enables to calculate the temperature of the hottest point of each capacitor in real-time. Then the calculation of the intrinsic difference ΔΘ1° between the average temperature values of the dielectric and the base average value of this temperatures during the second day from the start of the measurements. If the Dq1 value exceeds the value of the absolute error of simulation, diagnostic signals of abnormal levels of heating, viz. low, medium, high and very high, are generated. It is also necessary to calculate the rate of change of ΔΘ1° and to consider the values obtained in the formation of hazard levels. For the low level and the average level of hazard the operation of diagnostic system with a visual signal is recommended, while for the high level of hazard it is recommended to use both visual and sound signals, and for the very high hazard level the capacitor ought to be turned off from the source. The algorithms have been developed heuristically. The final formation of the algorithms is possible only after the long-term operation of the proposed diagnosis system on real objects. The implementation of the

  17. Capacitors on the basis of intercalate GaSe

    Directory of Open Access Journals (Sweden)

    Kovalyuk Z. D.

    2010-06-01

    Full Text Available The compound GaSe is obtained by the technique of intercalation of a GaSe single crystal in a melt of the ferroelectric salt KNO3. The x-ray analysis of its crystal structure has been carried out and dielectric frequency characteristics of samples has been measured. It is estab-lished, that accumulation of electric charges occurs in the examined examples in frequency area 100—1000 Hz. A sample of filter capacitor has been created on the basis of the re-ceived compounds.

  18. Graphene-Based Flexible and Transparent Tunable Capacitors

    OpenAIRE

    Man, Baoyuan; Xu, Shicai; Jiang, Shouzheng; Liu, Aihua; Gao, Shoubao; Zhang, Chao; Qiu, Hengwei; Li, Zhen

    2015-01-01

    We report a kind of electric field tunable transparent and flexible capacitor with the structure of graphene-Bi1.5MgNb1.5O7 (BMN)-graphene. The graphene films with low sheet resistance were grown by chemical vapor deposition. The BMN thin films were fabricated on graphene by using laser molecular beam epitaxy technology. Compared to BMN films grown on Au, the samples on graphene substrates show better quality in terms of crystallinity, surface morphology, leakage current, and loss tangent. By...

  19. High energy density, long life energy storage capacitor dielectric system

    International Nuclear Information System (INIS)

    Nichols, D.H.; Wilson, S.R.

    1977-01-01

    The evolution of energy storage dielectric systems shows a dramatic improvement in life and joule density, culminating in a 50% to 300% life improvement of polypropylene film-paper-phthalate ester over paper-castor oil depending on service. The physical and electrical drawbacks of castor oil are not present in the new system, allowing the capacitor designer to utilize the superior insulation resistance, dielectric strength, and corona resistance to full advantage. The result is longer life for equal joule density or greater joule density for equal life. Field service proof of the film-Geconol system superiority is based on 5 megajoule in operation and 16 megajoule on order

  20. Repetitively pulsed capacitor bank for the dense-plasma focus

    International Nuclear Information System (INIS)

    Zucker, O.; Bostick, W.; Gullickson, R.; Long, J.; Luce, J.; Sahlin, H.

    1976-01-01

    This report describes a 1 pulse per second capacitor bank designed to energize a dense-plasma focus (DPF). The DPF is a neutron source capable (with moderate scaling) of delivering a minimum of 10 15 neutrons per pulse or neutron flux of 2 x 10 13 N/cm 2 . s. The average power consumption, which has become a major issue due to the energy crisis, is analyzed with respect to other plasma devices and is shown to be highly favorable. This small source size high flux neutron source could be extremely useful to qualify fission reactor material irradiation results for fusion reactor design

  1. Ultra-capacitor flexible films with tailored dielectric constants using electric field assisted assembly of nanoparticles.

    Science.gov (United States)

    Batra, Saurabh; Cakmak, Miko

    2015-12-28

    In this study, the chaining and preferential alignment of barium titanate nanoparticles (100 nm) through the thickness direction of a polymer matrix in the presence of an electric field is shown. Application of an AC electric field in a well-dispersed solution leads to the formation of chains of nanoparticles in discrete rows oriented with their primary axis in the E-field direction due to dielectrophoresis. The change in the orientation of these chains was quantified through statistical analysis of SEM images and was found to be dependent on E-field, frequency and viscosity. When a DC field is applied a distinct layer consisting of dense particles was observed with micro-computed tomography. These studies show that the increase in DC voltage leads to increase in the thickness of the particle rich layer along with the packing density also increasing. Increasing the mutual interactions between particles due to the formation of particle chains in the "Z"-direction decreases the critical percolation concentration above which substantial enhancement of properties occurs. This manufacturing method therefore shows promise to lower the cost of the products for a range of applications including capacitors by either enhancing the dielectric properties for a given concentration or reduces the concentration of nanoparticles needed for a given property.

  2. The effects of dopants on the electrical resistivity in lead magnesium niobate multilayer ceramic capacitors

    International Nuclear Information System (INIS)

    Chang, D.D.; Ling, H.C.

    1989-01-01

    Electrical resistivity studies were performed on multilayer ceramic capacitors (MLC) based on lead magnesium niobate and containing dopants of lead titanate, lead zinc niobate, and lead cobalt niobate. The results showed that lead titanate and/or lead zinc niobate had no effect on the electrical resistivity while lead cobalt niobate decreased the resistivity. In samples without lead cobalt niobate, we observed a conduction mechanism with an activation energy of --1 eV, which is commonly observed in barium titanate based dielectrics. This is attributed to ionic conduction via the motion of oxygen vacancies. The increase in conductivity (or decrease in resistivity) resulting from the addition of lead cobalt niobate was rationalized as due to electronic conduction through charge hopping among the cations. This conduction mechanism was characterized by an activation energy of --0.5 eV. Since the activation energy associated with the long-term failure was previously determined by a matrix of temperature and voltage accelerated life tests to be -- 1 eV, they conclude that conduction through charge hopping is not affecting the long-term reliability of these devices

  3. Modeling error and stability of endothelial cytoskeletal membrane parameters based on modeling transendothelial impedance as resistor and capacitor in series.

    Science.gov (United States)

    Bodmer, James E; English, Anthony; Brady, Megan; Blackwell, Ken; Haxhinasto, Kari; Fotedar, Sunaina; Borgman, Kurt; Bai, Er-Wei; Moy, Alan B

    2005-09-01

    Transendothelial impedance across an endothelial monolayer grown on a microelectrode has previously been modeled as a repeating pattern of disks in which the electrical circuit consists of a resistor and capacitor in series. Although this numerical model breaks down barrier function into measurements of cell-cell adhesion, cell-matrix adhesion, and membrane capacitance, such solution parameters can be inaccurate without understanding model stability and error. In this study, we have evaluated modeling stability and error by using a chi(2) evaluation and Levenberg-Marquardt nonlinear least-squares (LM-NLS) method of the real and/or imaginary data in which the experimental measurement is compared with the calculated measurement derived by the model. Modeling stability and error were dependent on current frequency and the type of experimental data modeled. Solution parameters of cell-matrix adhesion were most susceptible to modeling instability. Furthermore, the LM-NLS method displayed frequency-dependent instability of the solution parameters, regardless of whether the real or imaginary data were analyzed. However, the LM-NLS method identified stable and reproducible solution parameters between all types of experimental data when a defined frequency spectrum of the entire data set was selected on the basis of a criterion of minimizing error. The frequency bandwidth that produced stable solution parameters varied greatly among different data types. Thus a numerical model based on characterizing transendothelial impedance as a resistor and capacitor in series and as a repeating pattern of disks is not sufficient to characterize the entire frequency spectrum of experimental transendothelial impedance.

  4. Process Optimization of P(VDF-TrFE)-BaTiO3 Nanocomposites for Storage Capacitor Applications

    KAUST Repository

    Almadhoun, Mahmoud N.

    2011-01-01

    are considered to be one possible solution towards the fabrication of high energy density capacitors, whether as embedded capacitors or gate insulators in organic field effect transistors (OFETs). Selecting high permittivity ceramics mixed with polymers with high

  5. Switched-capacitor multiply-by-two amplifier with reduced capacitor mismatches sensitivity and full swing sample signal common-mode voltage

    International Nuclear Information System (INIS)

    Xu Xinnan; Yao Suying; Xu Jiangtao; Nie Kaiming

    2012-01-01

    A switched-capacitor amplifier with an accurate gain of two that is insensitive to component mismatch is proposed. This structure is based on associating two sets of two capacitors in cross series during the amplification phase. This circuit permits the common-mode voltage of the sample signal to reach full swing. Using the charge-complement technique, the proposed amplifier can reduce the impact of parasitic capacitors on the gain accuracy effectively. Simulation results show that as sample signal common-mode voltage changes, the difference between the minimum and maximum gain error is less than 0.03%. When the capacitor mismatch is increased from 0 to 0.2%, the gain error is deteriorated by 0.00015%. In all simulations, the gain of amplifier is 69 dB. (semiconductor integrated circuits)

  6. Simulation and analysis of transient over voltages due to capacitor banks switching

    International Nuclear Information System (INIS)

    Jadid, Sh.; Yazdanpanah, D.

    2002-01-01

    The switching of any capacitor bank produces over voltages. Transient overvoltage will always occur in the switching device, the switching of shunt capacitor bank has become the most common source of transient voltage on power systems. Transient over voltages due to switching the capacitor bands hurt not only to the capacitor banks, but also to other equipment, such as circuit breakers and transformers. Several methods are available for reducing energising transients. These devices include pre-insertion resistors, pre-insertion inductors,synchronous closing, and MOV arresters. However, not all are practical or economical. The other important problem is existence of capacitor banks in presence of harmonics.Capacitors do not produce harmonics;however,the addition of capacitors to the electrical system will change the frequency response characteristics of the system will change the frequency response characteristics of the system, and in some cases can result in magnification of the voltage and current distortion in the system. In other word in presence of harmonic-producing loads,the capacitors used for power factor correction,may cause parallel resonance with the system inductance, so they increase the total harmonic distortion of voltage and current waveforms

  7. A Different Approach to Studying the Charge and Discharge of a Capacitor without an Oscilloscope

    Science.gov (United States)

    Ladino, L. A.

    2013-01-01

    A different method to study the charging and discharging processes of a capacitor is presented. The method only requires a high impedance voltmeter. The charging and discharging processes of a capacitor are usually studied experimentally using an oscilloscope and, therefore, both processes are studied as a function of time. The approach presented…

  8. The Most Energy Efficient Way to Charge the Capacitor in an RC Circuit

    Science.gov (United States)

    Wang, Dake

    2017-01-01

    The voltage waveform that minimizes the energy loss in the resistance when charging the capacitor in a resistor-capacitor circuit is investigated using the calculus of variation. A linear voltage ramp gives the best efficiency, which means a constant current source should be used for charging. Comparison between constant current source and…

  9. A 800 kV compact peaking capacitor for nanosecond generator.

    Science.gov (United States)

    Jia, Wei; Chen, Zhiqiang; Tang, Junping; Chen, Weiqing; Guo, Fan; Sun, Fengrong; Li, Junna; Qiu, Aici

    2014-09-01

    An extremely compact high voltage peaking capacitor is developed. The capacitor has a pancake structure with a diameter of 315 mm, a thickness of 59 mm, and a mass of 6.1 kg. The novel structural design endows the capacitor with a better mechanical stability and reliability under hundreds of kilovolts pulse voltage and an inner gas pressure of more than 1.5 MPa. The theoretical value of the capacitor self-inductance is near to 17 nH. Proved by series of electrical experiments, the capacitor can endure a high-voltage pulse with a rise time of about 20 ns, a half-width duration of around 25 ns, and an amplitude of up to 800 kV in a single shot model. When the capacitor was used in an electromagnetic pulse simulator as a peaking capacitor, the rise time of the voltage pulse can be reduced from 20 ns to less than 3 ns. The practical value of the capacitor's inductance deduced from the experimental date is no more than 25 nH.

  10. Modeling and fabrication of an RF MEMS variable capacitor with a fractal geometry

    KAUST Repository

    Elshurafa, Amro M.; Ho, P.H.; Salama, Khaled N.

    2013-01-01

    capacitor is increasing the tuning range of the variable capacitor beyond the typical ratio of 1.5. The modeling was carried out using the commercially available finite element software COMSOL to predict both the tuning range and pull-in voltage. Measurement

  11. Integrated hybrid switched-capacitor converter for LED drivers in 180 nm CMOS

    NARCIS (Netherlands)

    Castellanos Rodriguez, J.; Delos, J.; Hendrix, M.A.M.; Van Roermund, A.; Cantatore, E.

    2016-01-01

    This paper presents a LED driver based on a new Hybrid-Switched Capacitor Converter (H-SCC) operating in the MHz range, which uses the internal pulsed nodes of a Dickson converter and an LC output network to provide output current dimming. The converter is implemented using 5V integrated capacitors

  12. Pre-charging of module capacitors of MMC when the module ...

    Indian Academy of Sciences (India)

    Shamkant D Joshi

    The module capacitors need to be pre-charged, to power the control circuit. The problem faced while ... It consists of three legs to share a common DC link voltage. Each of these legs has ... Consider the stability of a system with only one capacitor with negative ..... number of wires because separate wires are not required for.

  13. Microcomputer based system to control the load of a capacitor array in the TJ-1 Tokamak

    International Nuclear Information System (INIS)

    Alberdi Primicia, J.; Asenjo, L.; Sanz, J.A.

    1990-01-01

    The power to create the magnetic field in the TJ-1 TOKAMAK is provide by an array of 16 capacitor sets. The total capacity of this array is 8.1F. This work describes a computer system based on the Motorola M-6800 microprocessor which controls the load of the capacitor set-and establishes the conditions for the reactor trigger. (author)

  14. Microcomputer Based System to control the Load of a Capacitor Array in the TJ-1 Tokamak

    International Nuclear Information System (INIS)

    Alberdi, J.; Asenso, L.; Sanz, J. A.

    1990-01-01

    The power to create the magnetic fields in the TJ-1 Tokamak is provides by an array of 16 capacitor sets. The total capacity of this array is 8. 1F. This work describes a computer system based on the Motorola M-6800 micro- processor which controls the load of the capacitor set and stablished the conditions for the reactor trigger. (Author)

  15. On battery-less autonomous polygeneration microgrids: Investigation of the combined hybrid capacitors/hydrogen alternative

    International Nuclear Information System (INIS)

    Kyriakarakos, George; Piromalis, Dimitrios D.; Arvanitis, Konstantinos G.; Dounis, Anastasios I.; Papadakis, George

    2015-01-01

    Highlights: • A battery-less autonomous polygeneration microgrid is technically feasible. • Laboratory testing of hybrid capacitors. • Investigation of hybrid capacitors utilization along with hydrogen subsystem. - Abstract: The autonomous polygeneration microgrid topology aims to cover holistically the needs in remote areas as far as electrical power, potable water through desalination, fuel for transportation in the form of hydrogen, heating and cooling are concerned. Deep discharge lead acid batteries are mostly used in such systems, associated with specific disadvantages, both technical and environmental. This paper investigated the possibility of replacing the battery bank from a polygeneration microgrid with a hybrid capacitor bank and more intensive utilization of a hydrogen subsystem. Initially commercial hybrid capacitors were tested under laboratory conditions and based on the respective results a case study was performed. The optimized combination of hybrid capacitors and higher hydrogen usage was then investigated through simulations and compared to a polygeneration microgrid featuring deep discharge lead acid batteries. From the results it was clear that it is technically possible to exchange the battery bank with a hybrid capacitor bank and higher hydrogen utilization. From the economic point of view, the current cost of the hybrid capacitors and the hydrogen components is high which leads to higher overall cost in comparison with deep discharge lead acid batteries. Taking into account, though, the decreasing cost prospects and trends of both the hybrid capacitors and the hydrogen components it is expected that this approach will become economically competitive in a few years

  16. A fast 30 kV 5 kHz repetition rate resonant capacitor charger

    NARCIS (Netherlands)

    Beckers, F.J.C.M.; Huiskamp, T.; van Heesch, E.J.M.; Pemen, A.J.M.

    2016-01-01

    A novel circuit topology of a fast 30 kV resonant capacitor charger is presented in this paper. The charger is designed for high repetition rate spark gap based pulsed power modulators. A spark gap can fire spontaneously (pre-firing) during charging of a capacitor bank due to poor dielectric

  17. Identifying dielectric and resistive electrode losses in high-density capacitors at radio frequencies

    NARCIS (Netherlands)

    Tiggelman, M.P.J.; Reimann, K.; Liu, J.; Klee, M.; Keur, W.; Mauczock, R.; Schmitz, Jurriaan; Hueting, Raymond Josephus Engelbart

    2008-01-01

    A regression-based technique is presented which distinguishes the dielectric loss from the resistive loss of high density planar capacitors in a very wide bandwidth of 0.1–8 GHz. Moreover, the procedure yields useful results if the capacitor deviates from a lumped element model and indicates when

  18. The impact of switching capacitor banks with very high inrush current on switchgear

    NARCIS (Netherlands)

    Smeets, R.P.P.; Wiggers, R.; Bannink, H.; Kuivenhoven, S.; Chakraborty, S.; Sandolache, G.

    2012-01-01

    Capacitor banks are installed in an increasing number in order to control power quality issues in the transmission and distribution networks. Due to load fluctuation, switching of capacitor banks is normally a daily operation. Although the current to be switched (e.g. the normal load current) is far

  19. Simple hardware implementation of voltage balancing in capacitor-clamped inverter

    Czech Academy of Sciences Publication Activity Database

    Kokeš, Petr; Semerád, Radko

    2009-01-01

    Roč. 54, č. 4 (2009), s. 325-341 ISSN 0001-7043 R&D Projects: GA MPO FT-TA4/077 Institutional research plan: CEZ:AV0Z20570509 Keywords : capacitor -clamped multilevel inverter * flying capacitor voltage balancing * pulse width modulation (PWM) Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

  20. Switched-capacitor techniques for high-accuracy filter and ADC design

    NARCIS (Netherlands)

    Quinn, P.J.; Roermund, van A.H.M.

    2007-01-01

    Switched capacitor (SC) techniques are well proven to be excellent candidates for implementing critical analogue functions with high accuracy, surpassing other analogue techniques when embedded in mixed-signal CMOS VLSI. Conventional SC circuits are primarily limited in accuracy by a) capacitor