Sample records for frequency sinusoidal voltage

  1. New voltage-mode universal filter and sinusoidal oscillator using only single DBTA

    Microsoft Academic Search

    Norbert Herencsár; Jaroslav Koton; Kamil Vrba; Ivo Lattenberg

    2010-01-01

    In this article, a new voltage-mode second-order universal frequency filter and sinusoidal oscillator using only single differential-input buffered and transconductance amplifier (DBTA) is presented. The proposed voltage-mode filter structure using single DBTA and four passive elements can provide all standard filter functions, i.e. low-, band-, high-pass, band-stop, and all-pass without changing the circuit topology and enables independent control of the

  2. High voltage VLF test equipment with sinusoidal waveform

    Microsoft Academic Search

    Ricliard Reid

    1999-01-01

    The problems associated with testing field aged XLPE cable using HVDC are now well documented. AC test equipment for field tests at power frequency also presents problems. The equipment required for such tests is large, heavy and expensive even with resonant test sets. Equipment producing very low frequency (VLF) high voltage has been used to some extent in the past.

  3. Theta-frequency resonance in hippocampal CA1 neurons in vitro demonstrated by sinusoidal current injection.

    PubMed

    Leung, L S; Yu, H W

    1998-03-01

    Sinusoidal currents of various frequencies were injected into hippocampal CA1 neurons in vitro, and the membrane potential responses were analyzed by cross power spectral analysis. Sinusoidal currents induced a maximal (resonant) response at a theta frequency (3-10 Hz) in slightly depolarized neurons. As predicted by linear systems theory, the resonant frequency was about the same as the natural (spontaneous) oscillation frequency. However, in some cases, the resonant frequency was higher than the spontaneous oscillation frequency, or resonance was found in the absence of spontaneous oscillations. The sharpness of the resonance (Q), measured by the peak frequency divided by the half-peak power bandwidth, increased from a mean of 0.44 at rest to 0.83 during a mean depolarization of 6.5 mV. The phase of the driven oscillations changed most rapidly near the resonant frequency, and it shifted about 90 degrees over the half-peak bandwidth of 8.4 Hz. Similar results were found using a sinusoidal function of slowly changing frequency as the input. Sinusoidal currents of peak-to-peak intensity of >100 pA may evoke nonlinear responses characterized by second and higher harmonics. The theta-frequency resonance in hippocampal neurons in vitro suggests that the same voltage-dependent phenomenon may be important in enhancing a theta-frequency response when hippocampal neurons are driven by medial septal or other inputs in vivo. PMID:9497437

  4. The State-of-Art Space-Voltage Vector Modulated Sinusoidal Three-Phase Inverter with High-Frequency Transformer-Coupled Resonant DC Link for High-Power Density UPS

    Microsoft Academic Search

    H. Yonemori; M. Michihira; M. Nakaoka

    1994-01-01

    Newly-improved Quasi-Resonant DC Link (QRDCL) three-phase voltage-sourced inverter circuit topology operating under a commutation principle of the high-frequency (HF) transformer-assisted Zero Voltage Switching (ZVS) is proposed. The basic operating principle of this power conversion circuit using Auxiliary Transformer-assisted QRDCL (TQRDCL) more suitable for CVCF\\/UPS, power active filter, switched-mode PWM converter, and new energy-interfaced power supplies for utility-interactive interconnection is presetted

  5. Energy-saving in constant speed running motors by means of adaptive sinusoidal voltage

    Microsoft Academic Search

    Shimon Limor; Doron Shmilovitz

    2011-01-01

    A transformer-based, purely sinusoidal, energy- saving controller for induction motors is presented. The controller applies a three-phase transformer in a reconfigurable scheme to create three different voltages. A simple control scheme is then applied to set the 'right voltage' to supply the motor. Significant reductions in the real and reactive power consumption were noticed, especially in motors operated under low

  6. Frequency to Voltage Converter Analog Front-End Prototype

    NASA Technical Reports Server (NTRS)

    Mata, Carlos; Raines, Matthew

    2012-01-01

    The frequency to voltage converter analog front end evaluation prototype (F2V AFE) is an evaluation board designed for comparison of different methods of accurately extracting the frequency of a sinusoidal input signal. A configurable input stage is routed to one or several of five separate, configurable filtering circuits, and then to a configurable output stage. Amplifier selection and gain, filter corner frequencies, and comparator hysteresis and voltage reference are all easily configurable through the use of jumpers and potentiometers.

  7. Transition to chaos in a simple nonlinear circuit driven by a sinusoidal voltage source

    Microsoft Academic Search

    ABDENNASSER AZZOUZ; RAYMOND DUHR; MARTIN HASLER

    1983-01-01

    A circuit composed of a sinusoidal voltage source, a linear resistor, a linear inductor, and a diode in series is investigated. Subharmonic solutions of various orders have been found by computer simulations and there is evidence for the presence of chaotic solutions. The diode model used involves a nonlinear capacitor. The transition to chaos follows the same pattern as for

  8. Neural Representations of Sinusoidal Amplitude and Frequency Modulations in the Primary Auditory Cortex of Awake Primates

    E-print Network

    Wang, Xiaoqin

    Neural Representations of Sinusoidal Amplitude and Frequency Modulations in the Primary Auditory. Neural representations of sinusoidal amplitude and frequency modulations in the auditory cortex of awake by different modulation frequencies. The main findings in- clude the following. 1) Responses of cortical

  9. Performance Study of a Cross-Frequency Detection Algorithm for Pulsed Sinusoidal RFI in Microwave Radiometry

    Microsoft Academic Search

    Noppasin Niamsuwan; Joel T. Johnson

    2010-01-01

    An analysis of the performance of a cross-frequency detection algorithm for pulsed sinusoidal radio frequency interference (RFI) is performed. The performance obtained is compared with that of pulse and kurtosis detection methods that have been previously reported. The results of the study show that the cross-frequency algorithm provides good performance in detecting pulsed sinusoidal RFI at high duty cycles, including

  10. Comparison of Pulsed Sinusoid Radio Frequency Interference Detection Algorithms Using Time and

    E-print Network

    Ruf, Christopher

    Comparison of Pulsed Sinusoid Radio Frequency Interference Detection Algorithms Using Time of two major Radio Frequency Interference (RFI) detection algorithms is compared. The peak detection ­ Microwave radiometry, radio frequency interference I. INTRODUCTION xtremely pervasive levels of Radio

  11. Suppression of epileptiform activity by high frequency sinusoidal fields in rat hippocampal slices

    PubMed Central

    Bikson, Marom; Lian, Jun; Hahn, Philip J; Stacey, William C; Sciortino, Christopher; Durand, Dominique M

    2001-01-01

    Sinusoidal high frequency (20–50 Hz) electric fields induced across rat hippocampal slices were found to suppress zero-Ca2+, low-Ca2+, picrotoxin, and high-K+ epileptiform activity for the duration of the stimulus and for up to several minutes following the stimulus. Suppression of spontaneous activity by high frequency stimulation was found to be frequency (< 500 Hz) but not orientation or waveform dependent. Potassium-sensitive microelectrodes showed that block of epileptiform activity was always coincident with a stimulus-induced rise in extracellular potassium concentration during stimulation. Post-stimulus inhibition was always associated with a decrease in extracellular potassium activity below baseline levels. Intracellular recordings and optical imaging with voltage-sensitive dyes showed that during suppression neurons were depolarized yet did not fire action potentials. Direct injection of sinusoidal current into individual pyramidal cells did not result in a tonic depolarization. Injection of large direct current (DC) depolarized neurons and suppressed action potential generation. These findings suggest that high frequency stimulation suppresses epileptiform activity by inducing potassium efflux and depolarization block. PMID:11179402

  12. An adaptive IIR structure for sinusoidal enhancement, frequency estimation, and detection

    Microsoft Academic Search

    D. R. Hush; N. Ahmed; R. David; S. D. Steams

    1986-01-01

    An adaptive IIR structure for processing a sinusoidal signal in broad-band noise is introduced. The structure contains three adaptive processors, each of which is computationally very simple. Useful features of the structure include enhancement, frequency estimation, and detection.

  13. ASSESSMENT OF NON-SINUSOIDAL, PULSED, OR INTERMITTENT EXPOSURE TO LOW FREQUENCY ELECTRIC AND MAGNETIC FIELDS

    Microsoft Academic Search

    Hannah Heinrich

    2007-01-01

    The correct assessment of non-sinusoidal, pulsed, or intermittent exposure to low frequency electric and magnetic fields already is a key issue in the occupational environment while becoming more and more important in the domain of the general public. The method presented provides a simple and safe solution for the assessment of arbitrary field types— including sinusoidal and continuous-wave signals—with fre-

  14. Sensitivity of the Kurtosis Statistic as a Detector of Pulsed Sinusoidal Radio Frequency Interference in a

    E-print Network

    Ruf, Christopher

    Sensitivity of the Kurtosis Statistic as a Detector of Pulsed Sinusoidal Radio Frequency@umich.edu Abstract--Radio frequency interference (RFI) from anthropogenic sources in microwave radiometers detecting-Detectors, digital radio, interference suppression, microwave radiometry. I. INTRODUCTION The kurtosis statistic

  15. Adaptive algorithms for the rejection of sinusoidal disturbances with unknown frequency

    Microsoft Academic Search

    Marc Bodson; Scott C. Douglas

    1997-01-01

    Two algorithms are presented for the rejection of sinusoidal disturbances with unknown frequency. The first is an indirect algorithm where the frequency of the disturbance is estimated, and the estimate is used in another adaptive algorithm that adjusts the magnitude and phase of the input needed to cancel the effect of the disturbance. A direct algorithm that uses the concept

  16. Frequency and parameter estimation of multi-sinusoidal signal

    NASA Astrophysics Data System (ADS)

    Petrovi?, P.

    2012-10-01

    Estimating the fundamental frequency and harmonic parameters is basic for signal modeling in a power supply system. This paper presents a complexity-reduced algorithm for signal reconstruction in the time domain from irregularly spaced sampling values. Differing from the existing parameter estimation algorithms, either in power quality monitoring or in harmonic compensation, the proposed algorithm enables a simultaneous estimation of the fundamental frequency, the amplitudes and phases of harmonic waves. The reduction in complexity is achieved owing to completely new analytical and summarized expressions that enable a quick estimation at a low numerical error. It is proved that the estimation performance of the proposed algorithm can attain Cramer-Rao lower bound (CRLB) for sufficiently high signal-to-noise ratios. The proposed algorithm can be applied in signal reconstruction, spectral estimation, system identification, as well as in other important signal processing problems. The simulation and experimental results verify the effectiveness of the proposed algorithm.

  17. Coding of small sinusoidal frequency and amplitude modulations in the inferior colliculus of ‘CF-FM’ bat, Rhinolophus ferrumequinum

    Microsoft Academic Search

    G. Schuller

    1979-01-01

    Single neurons in the inferior colliculus of the Greater Horseshoe bat, Rhinolophus ferrumequinum, showed two broad categories of response patterns to sinusoidally frequency (SFM) or amplitude (SAM) modulated stimuli. Tonic responding cells (best excitatory frequency (BEF) between 10 and 90 kHz) showed a rough sinusoidal modulation of the discharge pattern to SFM. Transient responding neurons, generally showing on- or off-responses

  18. Interaction between atom and radiation with sinusoidally shaped amplitude: Applications to frequency standards

    NASA Astrophysics Data System (ADS)

    Bava, E.; Shahian, A. G.

    1992-06-01

    The study of the evolution of a two-level atom crossing an electromagnetic field with a sinusoidally shaped amplitude is of interest in frequency metrology because a few Cs beam standards share this type of realization. The Magnus expansion method helps to find a solution to this problem giving approximate analytical results, which are made easy to handle by a series expansion in the detuning between atom resonance and radiation frequency. Numerical checks show that rather simple expressions provide an accuracy better than 10-3 in the matrix elements of the evolution operator for useful ranges of power levels and frequency differences. Two examples concerned with Cs beam standards are discussed.

  19. Blocking central pathways in the primate motor system using high-frequency sinusoidal current

    PubMed Central

    Fisher, Karen M.; Jillani, Ngalla E.; Oluoch, George O.

    2014-01-01

    Electrical stimulation with high-frequency (2–10 kHz) sinusoidal currents has previously been shown to produce a transient and complete nerve block in the peripheral nervous system. Modeling and in vitro studies suggest that this is due to a prolonged local depolarization across a broad section of membrane underlying the blocking electrode. Previous work has used cuff electrodes wrapped around the peripheral nerve to deliver the blocking stimulus. We extended this technique to central motor pathways, using a single metal microelectrode to deliver focal sinusoidal currents to the corticospinal tract at the cervical spinal cord in anesthetized adult baboons. The extent of conduction block was assessed by stimulating a second electrode caudal to the blocking site and recording the antidromic field potential over contralateral primary motor cortex. The maximal block achieved was 99.6%, similar to findings of previous work in peripheral fibers, and the optimal frequency for blocking was 2 kHz. Block had a rapid onset, being complete as soon as the transient activation associated with the start of the sinusoidal current was over. High-frequency block was also successfully applied to the pyramidal tract at the medulla, ascending sensory pathways in the dorsal columns, and the descending systems of the medial longitudinal fasciculus. High-frequency sinusoidal stimulation produces transient, reversible lesions in specific target locations and therefore could be a useful alternative to permanent tissue transection in some experimental paradigms. It also could help to control or prevent some of the hyperactivity associated with chronic neurological disorders. PMID:25475345

  20. Observation of Sinusoidal - Like Regular Voltage Oscillations in Silver Doped YBa2Cu3O7-x

    NASA Astrophysics Data System (ADS)

    Altinkok, Atilgan; Olutas, Murat; Kilic, Atilla; Kilic, Kivilcim

    2015-03-01

    The influence of bi-directional square wave (BSW) current was investigated on the evolution of the V - t curves at different periods (P) , temperatures and external magnetic fields. It was observed that slow transport relaxation measurements result in regular sinusoidal voltage oscillations which were discussed mainly in terms of the dynamic competition between pinning and depinning.The symmetry in the voltage oscillations was attributed to the elastic coupling between the flux lines and the pinning centers along grain boundaries and partly inside the grains. This case was also correlated to the equality between flux entry and exit along the YBCO/Ag sample during regular oscillations. It was shown that the voltage oscillations can be described well by an empirical expression V (t) ~ sin(wt + ?) . We found that the phase angle ?generally takes different values for the repetitive oscillations. Fast Fourier Transform analysis of the V - t oscillations showed that the oscillation period is comparable to that (PI) of the BSW current. This finding suggests a physical mechanism associated with charge density waves (CDWs), and, indeed, the weakly pinned flux line system in YBCO/Ag resembles the general behavior of CDWs. At certain values of PI, amplitude of BSW current, H and T, the YBCO/Ag sample behaves like a double-integrator, since it converts the BSW current to sinusoidal voltage oscillations in time. Giresun University.

  1. Nonlinear properties of medial entorhinal cortex neurons reveal frequency selectivity during multi-sinusoidal stimulation

    PubMed Central

    Magnani, Christophe; Economo, Michael N.; White, John A.; Moore, Lee E.

    2014-01-01

    The neurons in layer II of the medial entorhinal cortex are part of the grid cell network involved in the representation of space. Many of these neurons are likely to be stellate cells with specific oscillatory and firing properties important for their function. A fundamental understanding of the nonlinear basis of these oscillatory properties is critical for the development of theories of grid cell firing. In order to evaluate the behavior of stellate neurons, measurements of their quadratic responses were used to estimate a second order Volterra kernel. This paper uses an operator theory, termed quadratic sinusoidal analysis (QSA), which quantitatively determines that the quadratic response accounts for a major part of the nonlinearity observed at membrane potential levels characteristic of normal synaptic events. Practically, neurons were probed with multi-sinusoidal stimulations to determine a Hermitian operator that captures the quadratic function in the frequency domain. We have shown that the frequency content of the stimulation plays an important role in the characteristics of the nonlinear response, which can distort the linear response as well. Stimulations with enhanced low frequency amplitudes evoked a different nonlinear response than broadband profiles. The nonlinear analysis was also applied to spike frequencies and it was shown that the nonlinear response of subthreshold membrane potential at resonance frequencies near the threshold is similar to the nonlinear response of spike trains. PMID:25191226

  2. Rejection of disturbances with a large sinusoidal component of unknown frequency

    NASA Astrophysics Data System (ADS)

    Bodson, Marc; Douglas, Scott C.

    1996-05-01

    An important application of smart materials and structures is the control of periodic disturbances or vibration in environments such as aircrafts and helicopters. In these cases, the source of the noise is a rotating machine, so that a large component of the disturbance is periodic. While it is often possible to take measurements on the machine that is the source of the periodic disturbance, concerns of reliability and maintainability sometimes make such measurements undesirable, if not impossible. Then, the problem is to attenuate a periodic disturbance whose frequency is unknown. An adaptive algorithm is presented in this paper for periodic disturbance attenuation, using the concept of a phase-locked loop. For simplicity, the disturbance is assumed to be sinusoidal. An approximate analysis is performed and the results are found useful to select the design parameters. Simulations are presented that demonstrate the ability of the algorithm to reject sinusoidal disturbances with unknown frequency, and to follow signals with slowly varying magnitude and frequency. The effect of measurement noise and of additional disturbances is also analyzed. The results provide numerical measures of the parameter variations and of the loss of performance in the presence of noise.

  3. Neuroelectric mechanisms applied to low frequency electric and magnetic field exposure guidelines--part II: non sinusoidal waveforms.

    PubMed

    Reilly, J Patrick; Diamant, Alan M

    2002-09-01

    Standards for human exposure to electromagnetic fields typically express maximum permissible exposure limits as a function of frequency. Often, these limits have been derived from experiments or theoretical models involving sinusoidal waveforms. In many practical situations, however, the relevant waveforms of interest may not be sinusoidal, such as with waveforms having harmonic distortion, or with pulsed waveforms. This paper evaluates methods for applying sinusoidal exposure standards to non-sinusoidal waveforms in the frequency regime below a few MHz where electrostimulation is the dominant mechanism. Waveforms treated include those of a pulsed or mixed frequency variety. We evaluate acceptance criteria for mixed frequency exposure using summation formulae cited by IEEE C95.1, ICNIRP, and NRPB. This is carried out using a Fourier synthesis of various waveshapes. Also evaluated is an acceptance criterion based on the peak of the exposure waveform. Excitation thresholds are evaluated using a myelinated nerve model that accounts for the nonlinear electrodynamics of the neural membrane. It is shown that a method based on the peak and phase duration of the in situ field waveform provides a typically conservative test for compliance with non sinusoidal waveforms. An alternate method, based on amplitude summation of the Fourier components of the applied waveforms, can also provide a meaningful test, albeit a more conservative one. PMID:12199549

  4. Voltage Surges in Audio-Frequency Apparatus

    Microsoft Academic Search

    E. H. Fisher

    1929-01-01

    Transient voltages of over 2000 are shown to occur across the secondary when the normal plate current of a high inductance audio transformer is opened. The oscillograph and inverted vacuum tube are used to bring out further that these transients are oscillations of definite frequency and magnitude, depending on the primary current, inductance, and secondary distributed capacity. The manner of

  5. Space Vector PWM Techniques for Sinusoidal Output Voltage Generation with a Five-Phase Voltage Source Inverter

    Microsoft Academic Search

    Atif Iqbal; Emil Levi

    2006-01-01

    Five-phase variable-speed drives currently are considered for numerous applications, including electric and hybrid-electric vehicles, traction, and ship propulsion. If the machine is designed with a concentrated stator winding, the third stator current harmonic injection can be used to enhance the torque production and the machine needs to be supplied with the fundamental and the third harmonic of the voltage. On

  6. Load-Commutated SCR Current-Source-Inverter-Fed Induction Motor Drive With Sinusoidal Motor Voltage and Current

    Microsoft Academic Search

    Debmalya Banerjee; V. T. Ranganathan

    2009-01-01

    Current source inverter (CSI) is an attractive solution in high-power drives. The conventional gate turn-off thyristor (GTO) based CSI-fed induction motor drives suffer from drawbacks such as low-frequency torque pulsation, harmonic heating, and unstable operation at low-speed ranges. These drawbacks can be overcome by connecting a current-controlled voltage source inverter (VSI) across the motor terminal replacing the bulky ac capacitors.

  7. High-frequency graphene voltage amplifier.

    PubMed

    Han, Shu-Jen; Jenkins, Keith A; Valdes Garcia, Alberto; Franklin, Aaron D; Bol, Ageeth A; Haensch, Wilfried

    2011-09-14

    While graphene transistors have proven capable of delivering gigahertz-range cutoff frequencies, applying the devices to RF circuits has been largely hindered by the lack of current saturation in the zero band gap graphene. Herein, the first high-frequency voltage amplifier is demonstrated using large-area chemical vapor deposition grown graphene. The graphene field-effect transistor (GFET) has a 6-finger gate design with gate length of 500 nm. The graphene common-source amplifier exhibits ?5 dB low frequency gain with the 3 dB bandwidth greater than 6 GHz. This first AC voltage gain demonstration of a GFET is attributed to the clear current saturation in the device, which is enabled by an ultrathin gate dielectric (4 nm HfO(2)) of the embedded gate structures. The device also shows extrinsic transconductance of 1.2 mS/?m at 1 V drain bias, the highest for graphene FETs using large-scale graphene reported to date. PMID:21805988

  8. Phasors and Sinusoids

    NSDL National Science Digital Library

    Svoboda, James A.

    This interactive website from professor James A. Svoboda of Clarkson University describes phasors and sinusoids. Interactive graphs depict frequency and time domains. Users may change the phasor and see the resulting change in the sinusoid. You may also click inside the Frequency Domain box to see the change in the Time Domain.

  9. An amorphous alloy core medium frequency magnetic-link for medium voltage photovoltaic inverters

    NASA Astrophysics Data System (ADS)

    Rabiul Islam, Md.; Guo, Youguang; Wei Lin, Zhi; Zhu, Jianguo

    2014-05-01

    The advanced magnetic materials with high saturation flux density and low specific core loss have led to the development of an efficient, compact, and lightweight multiple-input multiple-output medium frequency magnetic-link. It offers a new route to eliminate some critical limitations of recently proposed medium voltage photovoltaic inverters. In this paper, a medium frequency magnetic-link is developed with Metglas amorphous alloy 2605S3A. The common magnetic-link generates isolated and balanced multiple DC supplies for all of the H-bridge inverter cells of the medium voltage inverter. The design and implementation of the prototype, test platform, and the experimental test results are analyzed and discussed. The medium frequency non-sinusoidal excitation electromagnetic characteristics of alloy 2605S3A are also compared with that of alloy 2605SA1. It is expected that the proposed new technology will have great potential for future renewable power generation systems and smart grid applications.

  10. Enormous stress response of anisotropic solution of poly(?-benzyl-L-glutamate) to sinusoidal electric fields with low frequencies unexplained by the electrohydrodynamic instability

    NASA Astrophysics Data System (ADS)

    Tanaka, Katsufumi; Takahashi, Akio; Akiyama, Ryuichi

    1998-08-01

    Transient stress responses to sinusoidal electric fields with frequencies lower than 1 Hz were reported for an anisotropic solution of poly(?-benzyl-L-glutamate). An enormous increase in stress with hysteresis was found at higher frequencies of the electric fields, while the smaller increase in stress with no hysteresis was found at the lowest frequency. These results are unexplained by the electrohydrodynamic instability.

  11. High voltage high frequency power transformer for pulsed power application

    Microsoft Academic Search

    Todor Filchev; Fabio Carastro; Pat Wheeler; Jon Clare

    2010-01-01

    This paper presents a new topology for a high voltage 50kV, high frequency (HF) 20kHz, multi-cored transformer. The transformer is suitable for use in pulsed power application systems. The main requirements are: high voltage capability, small size and weight. The HV, HF transformer is the main critical block of a high frequency power converter system. The transformer must have high

  12. Telecom-band single-photon detection with a gigahertz repetition frequency using a sinusoidally gated avalanche photodiode

    NASA Astrophysics Data System (ADS)

    Adachi, S.; Namekata, N.; Inoue, S.

    2009-04-01

    Single-photon detection at 1550 nm with a high repetition rate was realized using an InGaAs/InP avalanche photodiode operated with a sinusoidal gating. Removing the AC noise due to the transferred gate signal by use of band elimination filters, it is realized to detect much smaller avalanche signals than that in the conventional gating scheme, which results in the suppression of the afterpulsing. Finally, we achieved the detection efficiency of 11.0%, the dark count probability per gate of 7.7×10-7, and the afterpulsing probability was 3.3% at the repetition frequency of 1.2 GHz and the APD operating temperature of -50 degrees Celsius.

  13. Frequency, thermal and voltage supercapacitor characterization and modeling

    Microsoft Academic Search

    F. Rafik; H. Gualous; R. Gallay; A. Crausaz; A. Berthon

    2007-01-01

    A simple electrical model has been established to describe supercapacitor behaviour as a function of frequency, voltage and temperature for hybrid vehicle applications. The electrical model consists of 14 RLC elements, which have been determined from experimental data using electrochemical impedance spectroscopy (EIS) applied on a commercial supercapacitor.The frequency analysis has been extended for the first time to the millihertz

  14. Noise upon the sinusoids

    Microsoft Academic Search

    Kristoffer Jensen; Niels Bohrsvej

    2005-01-01

    Sinusoids are used for making harmonic and other sounds. In order to having life in the sounds and adding a wide variety of noises, irregularities are inserted in the frequency and amplitudes. A simple and intuitive noise model is presented, consisting of a low-pass filtered noise, and having control for strength and bandwidth. The noise is added on the frequency

  15. EE 188 Practice Problems for Exam 3, Spring 2009 Include units in your answers where appropriate. Assume that all circuits are in sinusoidal

    E-print Network

    Howard, Sheryl

    , Phasor Voltage and RMS Voltage: A sinusoidal voltage is given by v(t) = 25 cos(2000t + /3). 3(a). What is the phasor voltage V? V = 3(b). What is the radial frequency ? = 3(c). What is the phase offset in both 188 Practice Problems for Exam 3, Spring 2009 3 4. Phasor Domain and Source Transformation: Consider

  16. Coordination of Voltage and Frequency Feedback in Load-Frequency Control Capability of Wind Turbine

    E-print Network

    Silva, Filipe Faria Da

    Coordination of Voltage and Frequency Feedback in Load-Frequency Control Capability of Wind Turbine-Frequency Control (LFC) is gradually shifted to Variable Speed Wind Turbines (VSWTs). In order to equip VSWT@et.aau.dk Abstract--In near future, with high penetration of Wind Energy (WE) in power system, the burden of Load

  17. Impacts of high-frequency voltage on cable-terminations with resistive stressgrading

    Microsoft Academic Search

    Li Ming; F. Sahlen; S. Halen; G. Brosig; L. Palmqvist

    2004-01-01

    Behaviors of insulation system are strongly affected by frequency of the system voltages. In addition to power-frequency voltage, the insulation system could be also exposed to a voltage with frequency on the order of kHz due to application of new HV devices. Insulation failures under HF voltages occur not only because of lower breakdown strength of dielectric material under HF

  18. A High-Frequency Variable-Voltage-Fed Inverter

    Microsoft Academic Search

    Ali Mirbod; John M. Eldridge

    1986-01-01

    A half-bridge inverter circuit capable of providing a wide range of ac output voltages and frequencies is presented. The inverter uses asymmetrical thyristors (ASCR's), which have the advantages of high-power handling capability, small turn-on and turn-off times, and exhibit the same ruggedness associated with conventional thyristors in regards to surge current and gating requirements. By using ASCR's for the main

  19. High-frequency voltage oscillations in cultured astrocytes

    PubMed Central

    Fleischer, Wiebke; Theiss, Stephan; Slotta, Johannes; Holland, Christine; Schnitzler, Alfons

    2015-01-01

    Because of their close interaction with neuronal physiology, astrocytes can modulate brain function in multiple ways. Here, we demonstrate a yet unknown astrocytic phenomenon: Astrocytes cultured on microelectrode arrays (MEAs) exhibited extracellular voltage fluctuations in a broad frequency spectrum (100–600 Hz) after electrical stimulation. These aperiodic high-frequency oscillations (HFOs) could last several seconds and did not spread across the MEA. The voltage-gated calcium channel antagonist cilnidipine dose-dependently decreased the power of the oscillations. While intracellular calcium was pivotal, incubation with bafilomycin A1 showed that vesicular release of transmitters played only a minor role in the emergence of HFOs. Gap junctions and volume-regulated anionic channels had just as little functional impact, which was demonstrated by the addition of carbenoxolone (100 ?mol/L) and NPPB (100 ?mol/L). Hyperpolarization with low potassium in the extracellular solution (2 mmol/L) dramatically raised oscillation power. A similar effect was seen when we added extra sodium (+50 mmol/L) or if we replaced it with NMDG+ (50 mmol/L). The purinergic receptor antagonist PPADS suppressed the oscillation power, while the agonist ATP (100 ?mol/L) had only an increasing effect when the bath solution pH was slightly lowered to pH 7.2. From these observations, we conclude that astrocytic voltage oscillations are triggered by activation of voltage-gated calcium channels and driven by a downstream influx of cations through channels that are permeable for large ions such as NMDG+. Most likely candidates are subtypes of pore-forming P2X channels with a low affinity for ATP. PMID:25969464

  20. High-Frequency Response and Voltage Noise in Magnetic Nanocomposites

    NASA Astrophysics Data System (ADS)

    Buznikov, N. A.; Iakubov, I. T.; Rakhmanov, A. L.; Kugel, K. I.; Sboychakov, A. O.

    2010-12-01

    We study the noise spectra and high-frequency permeability of inhomogeneous magnetic materials consisting of single-domain magnetic nanoparticles embedded into an insulating matrix. Possible mechanisms of 1/f voltage noise in phase-separated manganites is analyzed. The material is modelled by a system of small ferromagnetic metallic droplets (magnetic polarons or ferrons) in insulating antiferromagnetic or paramagnetic matrix. The electron transport is related to tunnelling of charge carriers between droplets. One of the sources of the 1/f noise in such a system stems from fluctuations of the number of droplets with extra electron. In the case of strong magnetic anisotropy, the 1/f noise can arise also due to the fluctuations of the magnetic moments of ferrons. The high frequency magnetic permeability of nanocomposite film with magnetic particles in insulating non-magnetic matrix is studied in detail. The case of strong magnetic dipole interaction and strong magnetic anisotropy of ferromagnetic granules is considered. The composite is modelled by a cubic regular array of ferromagnetic particles. The high-frequency permeability tensor components are found as a functions of frequency, temperature, ferromagnetic phase content, and magnetic anisotropy. The results demonstrate that magnetic dipole interaction leads to a shift of the resonance frequencies towards higher values, and nanocomposite film could have rather high value of magnetic permeability in the microwave range.

  1. High-Frequency Response and Voltage Noise in Magnetic Nanocomposites

    NASA Astrophysics Data System (ADS)

    Buznikov, N. A.; Iakubov, I. T.; Rakhmanov, A. L.; Kugel, K. I.; Sboychakov, A. O.

    We study the noise spectra and high-frequency permeability of inhomogeneous magnetic materials consisting of single-domain magnetic nanoparticles embedded into an insulating matrix. Possible mechanisms of 1/f voltage noise in phase-separated manganites is analyzed. The material is modelled by a system of small ferromagnetic metallic droplets (magnetic polarons or ferrons) in insulating antiferromagnetic or paramagnetic matrix. The electron transport is related to tunnelling of charge carriers between droplets. One of the sources of the 1/f noise in such a system stems from fluctuations of the number of droplets with extra electron. In the case of strong magnetic anisotropy, the 1/f noise can arise also due to the fluctuations of the magnetic moments of ferrons. The high frequency magnetic permeability of nanocomposite film with magnetic particles in insulating non-magnetic matrix is studied in detail. The case of strong magnetic dipole interaction and strong magnetic anisotropy of ferromagnetic granules is considered. The composite is modelled by a cubic regular array of ferromagnetic particles. The high-frequency permeability tensor components are found as a functions of frequency, temperature, ferromagnetic phase content, and magnetic anisotropy. The results demonstrate that magnetic dipole interaction leads to a shift of the resonance frequencies towards higher values, and nanocomposite film could have rather high value of magnetic permeability in the microwave range.

  2. Systems and methods for process and user driven dynamic voltage and frequency scaling

    DOEpatents

    Mallik, Arindam (Evanston, IL); Lin, Bin (Hillsboro, OR); Memik, Gokhan (Evanston, IL); Dinda, Peter (Evanston, IL); Dick, Robert (Evanston, IL)

    2011-03-22

    Certain embodiments of the present invention provide a method for power management including determining at least one of an operating frequency and an operating voltage for a processor and configuring the processor based on the determined at least one of the operating frequency and the operating voltage. The operating frequency is determined based at least in part on direct user input. The operating voltage is determined based at least in part on an individual profile for processor.

  3. Understanding Pound-Drever-Hall locking using voltage controlled radio-frequency oscillators: An undergraduate experiment

    E-print Network

    Le Roy, Robert J.

    Understanding Pound-Drever-Hall locking using voltage controlled radio-frequency oscillators techniques using radio-frequency electronics. The primary objective is to frequency stabilize a volt- age is commonly applied to stabilize lasers at optical frequencies. By using only radio- frequency equipment

  4. Development of a high frequency and high-voltage pulse transformer for a TWT HVPS

    Microsoft Academic Search

    S. C. KimS; S. H. Nam; H. M. Keon; D. S. Park

    2003-01-01

    A pulse transformer for a high frequency and high voltage operation had been designed, fabricated, and tested. The high frequency operation of the pulse transformer increases power density. Therefore, it is possible to reduce power supply volume. To produce high voltage output, the transformer should have a high step-up ratio. The step-up ratio is generally limited in pulse transformers due

  5. Peripheral Aware Dynamic Voltage and Frequency Scaling for the Stargate Platform

    Microsoft Academic Search

    Rahul Balani

    Dynamic voltage and frequency scaling (DVS) for micro-processors seeks to minimize the energy consumption of the processor by scaling its voltage and frequency according to the workload. But, it has one major drawback - it accounts for only the energy consumption of the core processor, and not even of the other sub-systems on the chip, leave alone the peripherals attached

  6. Power Attack Resistant Cryptosystem Design: A Dynamic Voltage and Frequency Switching Approach

    E-print Network

    Boyer, Edmond

    Power Attack Resistant Cryptosystem Design: A Dynamic Voltage and Frequency Switching Approach|wolf}@princeton.edu {vijay|yuanxie}@cse.psu.edu {serpanos}@ee.upatras.gr Abstract-- A novel power attack resistant the power attacks, i.e., Dynamic Voltage and Frequency Switching (DVFS). Three designs, naive, improved

  7. Voltage Stability and Frequency Synchronization of Weak Power Distribution Networks with Inverter-Based

    E-print Network

    Lemmon, Michael

    Voltage Stability and Frequency Synchronization of Weak Power Distribution Networks with Inverter not apply to truly weak networks. Key words: Weak networks, inverter-based distributed generator, voltage and frequency stability. 1 INTRODUCTION Inverter-based distributed generation (DG) sources are usually a part

  8. Energy Aware Dynamic Voltage and Frequency Selection for Real-Time Systems with Energy Harvesting

    E-print Network

    Qiu, Qinru

    Energy Aware Dynamic Voltage and Frequency Selection for Real-Time Systems with Energy Harvesting}@binghamton.edu Abstract In this paper, an energy aware dynamic voltage and frequency selection (EA-DVFS) algorithm energy and the harvested energy in a future duration. Specifically, if the system has sufficient energy

  9. Assessing Method of Voltage Sag Frequency Caused by Transmission Line faults

    Microsoft Academic Search

    Xian-Yong Xiao; Chao Ma; Zheng-Guang Li; Yin Wang

    2009-01-01

    Fault location on transmission line influences the characteristics of voltage sag at given bus. It is difficult to determine the fault pattern and voltage sag frequency. A new method based on maximum entropy principle was proposed to assess sag frequency synthetically considered different fault types and objective probability distribution of fault location in the power system. The faulty line intervals

  10. Measured radial dependence of the peak sheath voltages present in very high frequency capacitive discharges

    Microsoft Academic Search

    E. V. Barnat; P. A. Miller; G. A. Hebner; A. M. Paterson; Theodoros Panagopoulos; Edward Hammond; J. Holland

    2007-01-01

    The radial distribution of the measured voltage drop across a sheath formed between a 300 mm electrode and an argon plasma discharge is shown to depend on the excitation radio frequency, under constant power and pressure conditions. At a lower frequency of 13.56 MHz, the voltage drop across the sheath is uniform across the 300 mm electrode, while at higher

  11. Measured radial dependence of the peak sheath voltages present in very high frequency capacitive discharges

    SciTech Connect

    Barnat, E. V.; Miller, P. A.; Hebner, G. A.; Paterson, A. M.; Panagopoulos, Theodoros; Hammond, Edward; Holland, J. [Sandia National Laboratories, Albuquerque, New Mexico 87185-1423 (United States); Applied Materials, 974 Arques Avenue, Sunnyvale, California 94086 (United States)

    2007-05-14

    The radial distribution of the measured voltage drop across a sheath formed between a 300 mm electrode and an argon plasma discharge is shown to depend on the excitation radio frequency, under constant power and pressure conditions. At a lower frequency of 13.56 MHz, the voltage drop across the sheath is uniform across the 300 mm electrode, while at higher frequencies of 60 and 162 MHz the voltage drop becomes radially nonuniform. The magnitude and spatial extent of the nonuniformity become greater with increasing frequency.

  12. Active voltage clamped edge-resonant soft switching PWM high frequency cycloconverter using bidirectional switches

    Microsoft Academic Search

    H. Sugimura; Sang-Pil Mun; Soon-Kurl Kwon; E. Hiraki; M. Nakaoka

    2008-01-01

    This paper presents a utility frequency AC (UFAC) to high frequency AC (HFAC) direct power frequency conversion pulse modulated conditioning circuit using bidirectional power switches. This power converter can efficiently operate under a principle of active zero voltage clamped soft commutation for consumer induction heating (IH) fixing roller for copy machine and printer. This HFAC direct power frequency converter defined

  13. Modulation linearization of a frequency-modulated voltage controlled oscillator, part 3

    NASA Technical Reports Server (NTRS)

    Honnell, M. A.

    1975-01-01

    An analysis is presented for the voltage versus frequency characteristics of a varactor modulated VHF voltage controlled oscillator in which the frequency deviation is linearized by using the nonlinear characteristics of a field effect transistor as a signal amplifier. The equations developed are used to calculate the oscillator output frequency in terms of pertinent circuit parameters. It is shown that the nonlinearity exponent of the FET has a pronounced influence on frequency deviation linearity, whereas the junction exponent of the varactor controls total frequency deviation for a given input signal. A design example for a 250 MHz frequency modulated oscillator is presented.

  14. Dynamic frequency and voltage control for a multiple clock domain microarchitecture

    Microsoft Academic Search

    Greg Semeraro; David H. Albonesi; Steven G. Dropsho; Grigorios Magklis; Sandhya Dwarkadas; Michael L. Scott

    2002-01-01

    We describe the design, analysis, and performance of an on-line algorithm to dynamically control the frequency\\/voltage of a Multiple Clock Domain (MCD) microarchitecture. The MCD microarchitecture allows the frequency\\/voltage of microprocessor regions to be adjusted independently and dynamically, allowing energy savings when the frequency of some regions can be reduced without significantly impacting performance. Our algorithm achieves on average a

  15. Will your motor insulation survive a new adjustable frequency drive?

    Microsoft Academic Search

    S. Bell; J. Sung

    1996-01-01

    The latest family of IGBT type adjustable frequency drives (AFD) produce voltage wave fronts that are extremely fast as a result of increasing carrier frequency. The frequency may be as high as 20 kHz. Motors which are designed for low voltage sinusoidal power run more efficiently and quieter under this condition. However, the insulation in small and medium size motors

  16. Water tree characteristics in low-density polyethylene under power-frequency voltages with high-frequency components

    Microsoft Academic Search

    Hidenori Suzuki; Yoshimichi Ohki; Yoshinobu Nakamichi; Kohji Ajiki

    1996-01-01

    For magnetic levitation railway systems using linear synchronous motors, pulse-width-modulation inverters and polymer insulated cables are used for driving cars and feeding electricity, respectively. This means that ac voltages with many harmonics induced by inverters are applied to cables. Water-tree characteristics have been investigated for low-density polyethylene using power-frequency ac voltages with high-frequency components. It was found that water trees

  17. Neuroelectric mechanisms applied to low frequency electric and magnetic field exposure guidelines--part I: sinusoidal waveforms.

    PubMed

    Reilly, J Patrick

    2002-09-01

    Electric and magnetic field exposure guidelines are developed from established mechanisms of bioelectric interaction. Such mechanisms involve phenomena of electrostimulation-the functional influence of applied electrical forces on nerve and muscle, and, at quasi-static frequencies, on magneto-dynamic mechanisms. The paper develops criteria of human reactions based on theoretical models with parametric values derived from experimental observations. These basic restrictions on electrostimulation effects are referenced to the induced in situ electric fields. Basic limitations are differentiated for induction in the heart, peripheral nerves, the extremities, and the central nervous system. The paper recommends maximum permissible exposure limits which account for (a) adverse reaction criteria, (b) statistical distribution of reaction thresholds, and (c) acceptability factors. From the basic limitations the paper further develops reference levels which apply to environmental electric or magnetic fields. PMID:12199548

  18. Understanding Pound-Drever-Hall locking using voltage controlled radio-frequency oscillators: An undergraduate experiment

    Microsoft Academic Search

    C. E. Liekhus-Schmaltz; J. D. D. Martin

    2011-01-01

    We have developed a senior undergraduate experiment that illustrates frequency stabilization techniques using radio-frequency electronics. The primary objective is to frequency stabilize a voltage controlled oscillator to a cavity resonance at 800 MHz using the Pound-Drever-Hall method. This technique is commonly applied to stabilize lasers at optical frequencies. By using only radio-frequency equipment it is possible to systematically study aspects

  19. Current mode integrators and their applications in low-voltage high frequency CMOS signal processing

    E-print Network

    Smith, Sterling Lane

    1993-01-01

    accuracy and linearity. To further complicate the design engineer's job, tbe power supply voltage is limited to 5v for most systems. The small supply voltages reduce the available signal swing in the analog circuits and limit the use of cascoding... of the requirements for the degree of MASTER OF SCIENCE December 1993 Major Subject: Electrical Engineering CURRENT MODE INTEGRATORS AND THEIR APPLICATIONS IN LOW-VOLTAGE HIGH FREQUENCY CMOS SIGNAL PROCESSING A Thesis by STERLING LANE SMITH Submitted to Texas...

  20. Accelerated aging tests on magnet wires under high frequency pulsating voltage and high temperature

    Microsoft Academic Search

    S. Grzybowski; E. A. Feilat; P. Knight

    1999-01-01

    Breakdown voltage and accelerated multistress aging tests were conducted on fine gauge magnet wire of heavy build insulation film of polyurethane resin with nylon overcoat. The aging tests were carried out under simultaneous high frequency pulsating voltages (15-40 kHz) and high temperatures (100-180°C). The effects of the duty cycle and rise time of the voltage pulse on the time-to-breakdown were

  1. Current mode integrators and their applications in low-voltage high frequency CMOS signal processing 

    E-print Network

    Smith, Sterling Lane

    1993-01-01

    Low voltage CMOS fully differential integrators for high frequency continuous-time filters using current-mode techniques are presented.. Current mode techniques are employed to avoid the use of the floating differential pair, in order to achieve...

  2. High frequency operation of a megawatt voltage source inverter equipped with ETOs

    Microsoft Academic Search

    Kevin Motto; Yuxin Li; Zhenxue Xu; Alex Q. Huang

    2001-01-01

    The fast switching speed, snubberless turn-off capability and voltage controlled turn-off property enable the emitter turn-off (ETO) thyristor the capability of high switching frequency-about 5-10 times as high as its GTO counterpart. A one-megawatt ETO-based voltage source inverter system is constructed with a switching frequency up to 3-5 kHz. Experimental results have shown that the ETO is a promising device

  3. A unifying explanation of complex frequency spectra of ? Dor, SPB and Be stars: combination frequencies and highly non-sinusoidal light curves

    NASA Astrophysics Data System (ADS)

    Kurtz, Donald W.; Shibahashi, Hiromoto; Murphy, Simon J.; Bedding, Timothy R.; Bowman, Dominic M.

    2015-07-01

    There are many Slowly Pulsating B (SPB) stars and ? Dor stars in the Kepler mission data set. The light curves of these pulsating stars have been classified phenomenologically into stars with symmetric light curves and with asymmetric light curves. In the same effective temperature ranges as the ? Dor and SPB stars, there are variable stars with downward light curves that have been conjectured to be caused by spots. Among these phenomenological classes of stars, some show `frequency groups' in their amplitude spectra that have not previously been understood. While it has been recognized that non-linear pulsation gives rise to combination frequencies in a Fourier description of the light curves of these stars, such combination frequencies have been considered to be a only a minor constituent of the amplitude spectra. In this paper, we unify the Fourier description of the light curves of these groups of stars, showing that many of them can be understood in terms of only a few base frequencies, which we attribute to g-mode pulsations, and combination frequencies, where sometimes a very large number of combination frequencies dominate the amplitude spectra. The frequency groups seen in these stars are thus tremendously simplified. We show observationally that the combination frequencies can have amplitudes greater than the base frequency amplitudes, and we show theoretically how this arises. Thus for some ? Dor and SPB stars, combination frequencies can have the highest observed amplitudes. Among the B stars are pulsating Be stars that show emission lines in their spectra from occasional ejection of material into a circumstellar disc. Our analysis gives strong support to the understanding of these pulsating Be stars as rapidly rotating SPB stars, explained entirely by g-mode pulsations.

  4. High power density, high frequency, and high voltage pulse transformer

    Microsoft Academic Search

    S. C. Kim; S. H. Nam; D. T. Kim

    2001-01-01

    Summary form only given, as follows. In designing a compact and high efficiency TWT microwave amplifier, the role of a high power density DC power supply is very important. In order to reduce volume of the power supply, it is necessary to increase switching frequency of the power supply. The high operation frequency mainly reduces transformer volume in the power

  5. High power density, high frequency, and high voltage pulse transformer

    Microsoft Academic Search

    S. C. Kim; S. H. Nam; S. H. Kim; D. T. Kim; S. H. Jeong

    2001-01-01

    In designing a compact and high efficiency TWT microwave amplifier, the role of a high power density DC power supply is very important. In order to reduce volume of the power supply, it is necessary to increase switching frequency of the power supply. The high operation frequency mainly reduces transformer volume in the power supply. However, a step-up ratio of

  6. Improvement of neurofeedback therapy for improved attention through facilitation of brain activity using local sinusoidal extremely low frequency magnetic field exposure.

    PubMed

    Zandi Mehran, Yasaman; Firoozabadi, Mohammad; Rostami, Reza

    2015-04-01

    Traditional neurofeedback (NF) is a training approach aimed at altering brain activity using electroencephalography (EEG) rhythms as feedback. In NF training, external factors such as the subjects' intelligence can have an effect. In contrast, a low-energy NF system (LENS) does not require conscious effort from the subject, which results in fewer attendance sessions. However, eliminating the subject role seems to eliminate an important part of the NF system. This study investigated the facilitating effect on the theta-to-beta ratio from NF training, using a local sinusoidal extremely low frequency magnetic field (LSELF-MF) versus traditional NF. Twenty-four healthy, intelligent subjects underwent 10 training sessions to enhance beta (15-18 Hz), and simultaneously inhibit theta (4-7 Hz) and high beta (22-30 Hz) activity, at the Cz point in a 3-boat-race video game. Each session consisted of 3 statuses, PRE, DURING, and POST. In the DURING status, the NF training procedure lasted 10 minutes. Subjects were led to believe that they would be exposed to a magnetic field during NF training; however, 16 of the subjects who were assigned to the experimental group were really exposed to 45 Hz-360 µT LSELF-MF at Cz. For the 8 other subjects, only the coil was located at the Cz point with no exposure. The duty cycle of exposure was 40% (2-second exposure and 3-second pause). The results show that the theta-to-beta ratio in the DURING status of each group differs significantly from the PRE and POST statuses. Between-group analysis shows that the theta-to-beta ratio in the DURING status of the experimental group is significantly (P < .001) lower than in the sham group. The result shows the effect of LSELF-MF on NF training. PMID:24939868

  7. A unifying explanation of complex frequency spectra of gamma Dor, SPB and Be stars: combination frequencies and highly non-sinusoidal light curves

    E-print Network

    Kurtz, Donald W; Murphy, Simon J; Bedding, Timothy R; Bowman, Dominic M

    2015-01-01

    There are many Slowly Pulsating B (SPB) stars and gamma Dor stars in the Kepler Mission data set. The light curves of these pulsating stars have been classified phenomenologically into stars with symmetric light curves and with asymmetric light curves. In the same effective temperature ranges as the gamma Dor and SPB stars, there are variable stars with downward light curves that have been conjectured to be caused by spots. Among these phenomenological classes of stars, some show `frequency groups' in their amplitude spectra that have not previously been understood. While it has been recognised that nonlinear pulsation gives rise to combination frequencies in a Fourier description of the light curves of these stars, such combination frequencies have been considered to be a only a minor constituent of the amplitude spectra. In this paper we unify the Fourier description of the light curves of these groups of stars, showing that many of them can be understood in terms of only a few base frequencies, which we at...

  8. The Coefficient of the Voltage Induced Frequency Shift Measurement on a Quartz Tuning Fork

    PubMed Central

    Hou, Yubin; Lu, Qingyou

    2014-01-01

    We have measured the coefficient of the voltage induced frequency shift (VIFS) of a 32.768 KHz quartz tuning fork. Three vibration modes were studied: one prong oscillating, two prongs oscillating in the same direction, and two prongs oscillating in opposite directions. They all showed a parabolic dependence of the eigen-frequency shift on the bias voltage applied across the fork, due to the voltage-induced internal stress, which varies as the fork oscillates. The average coefficient of the VIFS effect is as low as several hundred nano-Hz per millivolt, implying that fast-response voltage-controlled oscillators and phase-locked loops with nano-Hz resolution can be built. PMID:25414971

  9. Spin-torque diode radio-frequency detector with voltage tuned resonance

    SciTech Connect

    Skowro?ski, Witold, E-mail: skowron@agh.edu.pl; Frankowski, Marek; Stobiecki, Tomasz [AGH University of Science and Technology, Department of Electronics, Al. Mickiewicza 30, 30-059 Kraków (Poland); Wrona, Jerzy [AGH University of Science and Technology, Department of Electronics, Al. Mickiewicza 30, 30-059 Kraków (Poland); Singulus Technologies, Kahl am Main 63796 (Germany); Ogrodnik, Piotr [Faculty of Physics, Warsaw University of Technology, ul. Koszykowa 75, 00-662 Warsaw (Poland); AGH University of Science and Technology, Department of Electronics, Al. Mickiewicza 30, 30-059 Kraków (Poland); Barna?, Józef [Faculty of Physics, Adam Mickiewicz University, ul. Umultowska 85, 61-614 Pozna? (Poland); Institute of Molecular Physics, Polish Academy of Sciences, Smoluchowskiego 17, 60-179 Pozna? (Poland)

    2014-08-18

    We report on a voltage-tunable radio-frequency (RF) detector based on a magnetic tunnel junction (MTJ). The spin-torque diode effect is used to excite and/or detect RF oscillations in the magnetic free layer of the MTJ. In order to reduce the overall in-plane magnetic anisotropy of the free layer, we take advantage of the perpendicular magnetic anisotropy at the interface between ferromagnetic and insulating layers. The applied bias voltage is shown to have a significant influence on the magnetic anisotropy, and thus on the resonance frequency of the device. This influence also depends on the voltage polarity. The obtained results are accounted for in terms of the interplay of spin-transfer-torque and voltage-controlled magnetic anisotropy effects.

  10. Frequency and voltage dependence of glow and pseudoglow discharges in helium under atmospheric pressure

    Microsoft Academic Search

    Ion Radu; Ray Bartnikas; Michael R. Wertheimer

    2003-01-01

    The pseudoglow and glow discharge behavior of a 0.5-mm metallic-dielectric electrode gap in helium under atmospheric pressure was examined as a function of ac voltage between 0.3 and 32 kHz. The number of discharge current pulses per half-cycle within the pseudoglow was found to diminish with rising frequency, as opposed to the increase observed with rising voltage. The reduction in

  11. Variable speed constant frequency constant voltage alternator. Annual report

    SciTech Connect

    Grannemann, W.W.; Yang, C.E.; Seo, P.H.

    1980-07-01

    A test alternator is operated with digital control of its output frequency for variable shaft speed. The machine is a two-pole alternator with power removed through slip rings. The output frequency of the alternator is controlled by rotating the field by stepping through sixteen coils around the rotor. Usually four coils are active at one time. The rotating field in the stationary coils of the stator is controlled by microcircuits. The control circuits are constructed with available low-cost, low-power integrated circuits (ICs). The test results from the first test alternator indicate the feasibility of using this type of alternator to convert available wind power directly to usable 60 hertz power.

  12. Power supply and impedance matching to drive technological radio-frequency plasmas with customized voltage waveforms

    NASA Astrophysics Data System (ADS)

    Franek, James; Brandt, Steven; Berger, Birk; Liese, Martin; Barthel, Matthias; Schüngel, Edmund; Schulze, Julian

    2015-05-01

    We present a novel radio-frequency (RF) power supply and impedance matching to drive technological plasmas with customized voltage waveforms. It is based on a system of phase-locked RF generators that output single frequency voltage waveforms corresponding to multiple consecutive harmonics of a fundamental frequency. These signals are matched individually and combined to drive a RF plasma. Electrical filters are used to prevent parasitic interactions between the matching branches. By adjusting the harmonics' phases and voltage amplitudes individually, any voltage waveform can be approximated as a customized finite Fourier series. This RF supply system is easily adaptable to any technological plasma for industrial applications and allows the commercial utilization of process optimization based on voltage waveform tailoring for the first time. Here, this system is tested on a capacitive discharge based on three consecutive harmonics of 13.56 MHz. According to the Electrical Asymmetry Effect, tuning the phases between the applied harmonics results in an electrical control of the DC self-bias and the mean ion energy at almost constant ion flux. A comparison with the reference case of an electrically asymmetric dual-frequency discharge reveals that the control range of the mean ion energy can be significantly enlarged by using more than two consecutive harmonics.

  13. Kalman filter based high speed measurement and control of AC voltages for UPS applications

    Microsoft Academic Search

    Seshadri Sivakumar; K. Natarajan

    1993-01-01

    A scheme is proposed for high speed measurement and processing of AC voltages encountered in offline uninterruptible power supplies (UPSs) based on the design of a Kalman filter with an internal model of the sinusoidal waveform. The proposed scheme provides a common framework to monitor the UPS mains input supply, to sense its out-of-specification voltage and frequency conditions, and to

  14. Adaptive Algorithms for the Rejection of Sinusoidal Disturbances

    E-print Network

    Douglas, Scott C.

    of such noises include engine noise in turboprop aircraft (Emborg and Ross, 1993), engine noise in automobilesAdaptive Algorithms for the Rejection of Sinusoidal Disturbances with Unknown Frequency Marc Bodson Abstract Two algorithms are presented for the rejection of sinusoidal disturbances with un­ known frequency

  15. Zero Voltage Soft Switching Duty Cycle Pulse Modulated High Frequency Inverter-Fed

    NASA Astrophysics Data System (ADS)

    Ishitobi, Manabu; Matsushige, Takayuki; Nakaoka, Mutsuo; Bessyo, Daisuke; Omori, Hideki; Terai, Haruo

    The utility grid voltage of commercial AC power source in Japan and USA is 100V, but in other Asian and European countries, it is 220V. In recent years, in Japan 200V outputted single-phase three-wire system begins to be used for high power applications. In 100V utility AC power applications and systems, an active voltage clamped quasi-resonant inverter circuit topology sing IGBTs has been effectively used so far for the consumer microwave oven. In this paper, presented is a half bridge type voltage-clamped asymmetrical soft switching PWM high-frequency inverter type AC-DC converter using IGBTs which is designed for consumer magnetron drive used as the consumer microwave oven in 200V utility AC power system. The zero voltage soft switching inverter treated here can use the same power rated switching semiconductor devices and three-winding high frequency transformer as those of the active voltage clamped quasi-resonant inverter using the IGBTs that has already been used for 100V utility AC power source. The operating performances of the voltage source single ended push pull (SEPP) type soft switching PWM inverter are evaluated and discussed for 100V and 200V common use consumer microwave oven. The harmonic line current components in the utility AC power side of the AC-DC power converter with ZVS-PWM SEPP inverter are reduced and improved on the basis of sine wave like pulse frequency modulation and sine wave like pulse width modulation for the utility AC voltage source.

  16. Fast adaptive schemes for tracking voltage phasor and local frequency in power transmission and distribution systems

    SciTech Connect

    Kamwa, I.; Grondin, R. (Inst. de Recherche d'Hydro-Quebec, 1800, montee Ste-Julie, Varennes, Quebec J3X 1S1 (CA))

    1992-04-01

    Real-time measurements of voltage phasor and local frequency deviation find applications in computer-based relaying, static state estimation, disturbance monitoring and control. This paper proposes two learning schemes for fast estimation of these basic quantities. We attacked the problem from a system identification perspective, in opposition to the well-established Extended Kalman Filtering (EKF) technique. It is shown that, from a simple non-linear model of the system voltage which involves only two parameters, the Recursive Least Squares (RLS) and the Least Means Squares (LMS) algorithms can each provide dynamic estimates of the voltage phasor. The finite derivative of the phase deviation, followed by a moving-average filter, then leads to the local frequency deviation. A constant forgetting factor included in these algorithms provides both fast adaptation in time-varying situations and good smoothing of the estimates when necessary.

  17. Frequency Coupling Matrix of a Voltage-Source Converter Derived From Piecewise Linear Differential Equations

    Microsoft Academic Search

    P. W. Lehn; K. L. Lian

    2007-01-01

    When a power-electronic converter is introduced into a linear network, voltage and current harmonics of differing orders become coupled (through the modulation effect of the converter). The interharmonic coupling introduced by the modulation effect of a converter may be mathematically represented through a frequency coupling matrix (FCM). Given that the source of the coupling is a modulation process, researchers have,

  18. Distributed DVFS using rationally-related frequencies and discrete voltage levels

    Microsoft Academic Search

    Jean-Michel Chabloz; Ahmed Hemani

    2010-01-01

    We have defined a flexible latency-insensitive design style called Globally Ratiochronous Locally Synchronous (GRLS), based on quantized voltage levels and rationally-related clock frequencies. In this paper we present the infrastructure necessary to enable Distributed DVFS in such a system and analyze its overheads, quantitatively showing how, with minimal overheads, we obtain energy benefits that are close to those of a

  19. The proposed use of GPS to provide the frequency traceability for a Josephson array voltage standard

    SciTech Connect

    Marais, E.L. [National Metrology Lab., Pretoria (South Africa)

    1994-12-31

    A Josephson Array Voltage Standard (JAVS) has been established at the National Metrology Laboratory (NML) in South Africa, with the assistance of NIST and the PTB. We are currently working on what we believe to be the first use of the global positioning system (GPS) to provide direct frequency traceability for a JAVS.

  20. Voltage phasor and local system frequency estimation using Newton type algorithm

    Microsoft Academic Search

    V. V. Terzija; M. B. Djuric; B. D. Kovacevic

    1994-01-01

    A new approach to the design of digital algorithm for voltage phasor and local system frequency estimation is presented. The estimation problem is considered as an unconstrained optimization problem. The algorithm is derived using Newton's iterative method, very commonly used in Load-Flow studies. The algorithm showed a very high level of robustness as well as high measurement accuracy over a

  1. Understanding Pound-Drever-Hall locking using voltage controlled radio-frequency oscillators: An undergraduate experiment

    E-print Network

    Liekhus-Schmaltz, C E

    2011-01-01

    A senior undergraduate experiment has been developed for learning about frequency stabilization techniques using radio-frequency electronics. The primary objective is to frequency stabilize a voltage controlled oscillator to a cavity resonance at 800 MHz using the Pound-Drever-Hall scheme. This technique is commonly applied to stabilize lasers at optical frequencies, but by using radio-frequency equipment exclusively it is possible to systematically study various aspects of the technique more thoroughly, inexpensively, and free from eye hazards. Students also learn about modular radio-frequency electronics and basic feedback control loops. By varying the temperature of the resonator, the students may determine the thermal expansion coefficients of copper, aluminum, and super invar.

  2. Sinusoids and Phasors.

    ERIC Educational Resources Information Center

    Balabanian, Norman; Root, Augustin A.

    This programed booklet is designed for the engineering student who is familiar with integral calculus and electrical networks. The first portion of this booklet is concerned with sinusoids, their properties, and their mathematical and graphical representations. The second portion is concerned with phasors and the mathematical relationship between…

  3. Sinusoids: Applications and Modeling

    NSDL National Science Digital Library

    Roberts, Lila F.

    2004-07-21

    This demo actively involves students via the software simulations so that the determination of the sinusoidal model has a geometric flavor that complements the algebraic tools stressed in texts. This approach also introduces a modeling aspect since in some situations we may only be able to obtain a "close" approximation to the actual curve or data. Animations and Excel routines are included.

  4. Challenges and opportunities for multi-functional oxide thin films for voltage tunable radio frequency/microwave components

    E-print Network

    Chen, Long-Qing

    and opportunities for multi-functional oxide thin films for voltage tunable radio frequency/microwave components varactor technology based reconfigurable radio frequency (RF)/microwave components have been demonstratedChallenges and opportunities for multi-functional oxide thin films for voltage tunable radio

  5. High voltage pulse power supply of piezoelectric transformer based on adaptive frequency tracking control

    NASA Astrophysics Data System (ADS)

    Guo, Ze-rong; Bai, Chun-yu; Li, Hua-bo

    2010-07-01

    The damage capacity of weapon systems is enhanced when all-electronic safety and arming device (ESAD) is applied, so that ESAD has been favored by the military power. ESAD must ensure the normal work in the stipulation of -40 °C ~ +60°C temperature. When high voltage pulse power supply of piezoelectric transformer (PT) is used in ESAD the charging time has the large dispersion and affects the striking capability of weapon systems. In order to control the inconsistency charging time due to environment temperature change the adaptive frequency tracking control system for high-voltage pulse power supply of PT is designed. Theoretical calculation of current lag angle under zero voltage switching condition for resonant current is derived. Sampling circuit and control circuit are designed by applying the phase-locked loop (PLL) control technology. Experiment results have proved that this control can ensure the consistency of converter output under different environment.

  6. Breakdown voltages for discharges initiated from plasma pulses produced by high-frequency excimer lasers

    SciTech Connect

    Yamaura, Michiteru [Department of Electrical and Electronic Engineering, Faculty of Science and Engineering, Saga University, 1 Honjo-machi, Saga 840-8502 (Japan)

    2006-06-19

    The triggering ability under the different electric field was investigated using a KrF excimer laser with a high repetition rate of kilohertz order. Measurements were made of the magnitude of impulse voltages that were required to initiate a discharge from plasmas produced by a high-frequency excimer laser. Breakdown voltages were found to be reduced by 50% through the production of plasmas in the discharge gap by a high-frequency excimer laser. However, under direct-current electric field, triggering ability decreased drastically due to low plasma density. It is considered that such laser operation applied for laser-triggered lightning due to the produced location of plasma channel is formed under the impulse electric field since an electric field of the location drastically reduces temporary when the downward leader from thunderclouds propagates to the plasma channel.

  7. HEPATIC SINUSOIDAL ENDOTHELIUM IN GOATS

    Microsoft Academic Search

    PL Wright; JA Clemett; KF Smith; WA Day; R Fraser

    1983-01-01

    The ultrastructure of the hepatic sinusoids of the goat was examined. Contrary to current belief concerning this and other ruminant species, we found the sinusoids to be lined by a smooth, continuous layer of endothelium, broken only by the presence of numerous, unoccluded fenestrae which provide a direct path of communication between the sinusoidal lumen and the space of Disse.

  8. Frequency and Time Domain Characterization of Transient Voltages through Low-Voltage Motor Stator Coils Fed with Inverter Pulses

    Microsoft Academic Search

    J. M. Martínez-Tarifa; J. Sanz-Feito; H. Amarís-Duarte

    2007-01-01

    The application of inverter-fed drives provides additional electrical stresses in induction motors' insulation system. This is due to steep-fronted voltage pulses responsible for high overvoltages at the motor's input terminals and to an uneven voltage distribution along the windings. This article presents a model for the analysis and characterization of the internal voltage distribution and complex impedance in random wound

  9. Fast adaptive schemes for tracking voltage phasor and local frequency in power transmission and distribution systems

    Microsoft Academic Search

    I. Kamwa; R. Grondin

    1992-01-01

    Real-time measurements of voltage phasor and local frequency deviation find applications in computer-based relaying, static state estimation, disturbance monitoring and control. This paper proposes two learning schemes for fast estimation of these basic quantities. We attacked the problem from a system identification perspective, in opposition to the well-established Extended Kalman Filtering (EKF) technique. It is shown that, from a simple

  10. A new technique to reject dc-link voltage ripple in PWM inverters 

    E-print Network

    Shireen, Wajiha

    1990-01-01

    utilities. Iuverter power supplies ivhich employ pulse width modulation techniques are therefore being used to provide variable voltage at a. fixed or variable frequency for a, variety of applications High quality output, voltage can be achieved... Ripple II. 4. 1 Example Calculation II. 4. 2 Simulation Results II. 4. 3 Inverter Output Voltage Quality II. 5 Inverter Operation With Naturally Sampled PWM II. 5. 1 Sinusoidal Pulse Width Modulation (SPWM) II. 5. 2 Harmonic Injection PWM (HIPWM...

  11. Wind-driven self-excited induction generator with voltage and frequency regulated by a reduced-rating voltage source inverter

    Microsoft Academic Search

    Luiz A. C. Lopes; R. G. Almeida

    2006-01-01

    This paper discusses the regulation of the voltage and frequency of a stand-alone fixed-pitch wind energy conversion system (WECS) based on a self-excited squirrel-cage induction machine. A shunt connected voltage source inverter (VSI) and a controllable dump load are used for regulation purposes. A battery bank is included in the dc side of the VSI so that it can absorb

  12. Numerical investigation of the effect of driving voltage pulse shapes on the characteristics of low-pressure argon dielectric barrier discharge

    NASA Astrophysics Data System (ADS)

    Eslami, E.; Barjasteh, A.; Morshedian, N.

    2015-06-01

    In this work, we numerically compare the effect of a sinusoidal, triangular, and rectangular pulsed voltage profile on the calculated particle production, electric current, and gas voltage in a dielectric barrier discharge. The total argon gas pressure of 400 Pa, the distance between dielectrics of 5 mm, the dielectric thickness of 0.7 mm, and the temperature of T = 300 K were considered as input parameters. The different driving voltage pulse shapes (triangular, rectangular, and sinusoidal) are considered as applied voltage with a frequency of 7 kHz and an amplitude of 700 V peak to peak. It is shown that applying a rectangular voltage, as compared with a sinusoidal or triangle voltage, increases the current peak, while the peak width is decreased. Higher current density is related to high production of charged particles, which leads to the generation of some highly active species, such as Ar* (4 s level), and Ar** (4 p level) in the gap.

  13. Inductor snubber-assisted series resonant ZCS-PFM high frequency inverter link DC-DC converter with voltage multiplier

    Microsoft Academic Search

    Koki Ogura; Enhui Chu; Manabu Ishitobi; Mantaro Nakamura; Mutsuo Nakaoka

    2002-01-01

    A variety of high voltage DC power supplies employing the high frequency inverter have difficulty in achieving soft switching considering a quick response and no overshoot response under the wide load conditions which are used in a medical-use X-ray high voltage generator ranging from 20 kV to 150 kV in the output voltage and from 0.5 mA to 1.25 A,

  14. Ultra-Low-Voltage 20GHz Frequency Dividers Using Transformer Feedback in 0.18- m CMOS Process

    Microsoft Academic Search

    Hui Zheng; Howard C. Luong

    2008-01-01

    This paper presents the design and analysis of ultra- low-voltage (ULV) high-frequency dividers using transformer feedback. Specifically, a differential-input differential-output injection-locked (IL) divider topology with transformer feedback and a wideband transformer-coupled (TC) divider with quadrature outputs are demonstrated, both of which can operate well at supply voltages as low as the device's threshold voltages. Fabricated in a standard 0.18-mum CMOS

  15. Breaking the ice: de-icing power transmission lines with high-frequency, high-voltage excitation

    E-print Network

    Breaking the ice: de-icing power transmission lines with high-frequency, high-voltage excitation. High-frequency excitation at approximately 8-200 kHz has been proposed as a method to melt ice [1], [2]. The method works by a combination of two mechanisms. At these frequencies, ice is a lossy dielectric, causing

  16. Frequency-Domain Maximum-Likelihood Estimation of High-Voltage Pulse Transformer Model Parameters

    E-print Network

    Aguglia, D

    2014-01-01

    This paper presents an offline frequency-domain nonlinear and stochastic identification method for equivalent model parameter estimation of high-voltage pulse transformers. Such kinds of transformers are widely used in the pulsed-power domain, and the difficulty in deriving pulsed-power converter optimal control strategies is directly linked to the accuracy of the equivalent circuit parameters. These components require models which take into account electric fields energies represented by stray capacitance in the equivalent circuit. These capacitive elements must be accurately identified, since they greatly influence the general converter performances. A nonlinear frequency-based identification method, based on maximum-likelihood estimation, is presented, and a sensitivity analysis of the best experimental test to be considered is carried out. The procedure takes into account magnetic saturation and skin effects occurring in the windings during the frequency tests. The presented method is validated by experim...

  17. Voltage phasor and local system frequency estimation using Newton type algorithm

    SciTech Connect

    Terzija, V.V.; Djuric, M.B.; Kovacevic, B.D. (Univ. of Belgrade (Yugoslavia))

    1994-07-01

    A new approach to the design of digital algorithm for voltage phasor and local system frequency estimation is presented. The estimation problem is considered as an unconstrained optimization problem. The algorithm is derived using Newton's iterative method, very commonly used in Load-Flow studies. The algorithm showed a very high level of robustness as well as high measurement accuracy over a wide range of frequency changes. The algorithm convergence of order two provided fast response and adaptability. To demonstrate the performance of the algorithm developed, computer simulated, experimentally obtained and real-life data records are processed. The presented work is a part of a project concerning the application of microprocessors in frequency relaying.

  18. An improved zero voltage soft switching PWM high-frequency inverter with active inductor snubber for induction heated roller

    Microsoft Academic Search

    Youichi Kurose; Satoshi Muraoka; Sarawouth Chandhaket; Atsushi Okuno; M. Nakaoka

    2002-01-01

    This paper presents a novel version of an active voltage clamped ZVS-PWM high frequency inverter using IGBTs for electromagnetic induction eddy current-based rolling drum heating in new generation copy and printing machines in consumer business use. The operating principle of this inverter circuit and unique features are described herein. Its constant frequency duty cycle (asymmetrical PWM) controlled voltage source quasi-resonant

  19. An investigation into a method of detecting the fault induced high frequency voltage signals of EHV transmission lines for protection applications

    Microsoft Academic Search

    P. L. Agrawal

    1991-01-01

    This paper investigates a method of detecting the fault induced high frequency voltage signals of the EHV transmission lines for the protection applications. The method is based on the principle of power line carrier communication system using a stack tuner for detecting the high frequency voltage signals in a particular frequency bandwidth. The digitally simulated fault responses of different frequency

  20. An approach to eliminating high-frequency shaft voltage and ground leakage current from an inverter-driven motor

    Microsoft Academic Search

    Hirofumi Akagi; Takafumi Doumoto

    2004-01-01

    This paper proposes a small-sized passive electromagnetic interference (EMI) filter for the purpose of eliminating high-frequency shaft voltage and ground leakage current from an ac motor driven by a voltage-source pulsewidth-modulation inverter. The filter requires access to the neutral point of the motor. A common-mode inductor is connected between the inverter and the motor. The neutral point of the motor

  1. Timesharing space-voltage vector controlled inverter with new high-frequency transformer-assisted quasi-resonant DC link

    Microsoft Academic Search

    H. Yonemori; M. Nakaoka

    1993-01-01

    A newly-improved quasi-resonant DC link (QRDCL) circuit topology operating under a commutation principle of the HF transformer-assisted zero voltage soft switching is proposed. The basic operating principle of this improved power conversion circuit (auxiliary transformer-assisted QRDCL TQRDCL) which is more suitable with the power factor correction input DC side expected in constant voltage-constant frequency (CVCF) UPS, power active filters and

  2. Frequency-Domain Model for Calculation of Voltage Distribution Through Random Wound Coils and Its Interaction With Stray Capacitances

    Microsoft Academic Search

    Juan M. MartÍnez-Tarifa; Hortensia AmarÍs-Duarte; Javier Sanz-Feito

    2008-01-01

    Modern pulsewidth-modulation (PWM) low-voltage drives are recognized as one of the most demanding applications for a motor. Pulses facing motor terminals are responsible for turn-to-turn high electrical stresses that lead to unexpected failures in stator windings. In this paper, an accurate new model for frequency-domain voltage distribution calculation through random wound coils is presented. In addition to checking its applicability

  3. Steering car-like systems with trailers using sinusoids

    Microsoft Academic Search

    D. Tilbury; J.-P. Laumond; R. Murray; S. Sastry; G. Walsh

    1992-01-01

    Methods for steering car-like robots with trailers are investigated. A connection is demonstrated between Murray and Sastry's (1990, 1991) work of steering with integrally related sinusoids and Sussmann and Liu's (1991) recent work on asymptotic behavior of systems with high-frequency sinusoids as inputs. The merits of coordinate transformations, relative to the convergence properties, are discussed. Simulation results for a car-like

  4. A sinusoidal-vibration analysis program for experimental data

    NASA Technical Reports Server (NTRS)

    Schoenster, J. A.; Taylor, N. L.

    1973-01-01

    A program is described for obtaining resonant frequencies, modal amplitudes, and damping of a structure from a sinusoidal force-controlled vibration test. Presented are the theoretical basis for the analysis (the Kennedy-Pancu method), recommendations for a test procedure based on experience with several earlier test programs, and an outline of the data analysis technique. Although the program was developed for structural vibration problems, variations for processing any sinusoidal data are available.

  5. Sampling piecewise sinusoidal signals with finite rate of innovation methods

    Microsoft Academic Search

    Jesse Berent; Pier Luigi Dragotti; Thierry Blu

    2010-01-01

    We consider the problem of sampling piecewise sinu- soidalsignals.Classicalsamplingtheorydoesnotenableperfectre- construction of such signals since they are not band-limited. How- ever, they can be characterized by a finite number of parameters, namely, the frequency, amplitude, and phase of the sinusoids and thelocationofthediscontinuities.Inthispaper,weshowthatunder certainhypothesesonthesamplingkernel,itispossibletoperfectly recover the parameters that define the piecewise sinusoidal signal from its sampled version. In particular, we show that,

  6. A Near State PWM Method With Reduced Switching Frequency And Reduced Common Mode Voltage

    E-print Network

    Hava, Ahmet

    -Phase Voltage Source Inverters Emre Ün Ahmet M. Hava Department of Electrical and Electronics Engineering Middle, DPWM. I. INTRODUCTION Three-phase Voltage Source Inverters (VSI) are widely utilized to drive AC motors-phase PWM inverter drives. The optimal voltage vectors and their sequences are determined. The voltage

  7. Will your motor insulation survive a new adjustable-frequency drive?

    Microsoft Academic Search

    Sidney Bell; Jason Sung

    1997-01-01

    The latest family of insulated-gate-bipolar-transistor (IGBT)-type adjustable-frequency drives (AFDs) produce voltage wavefronts that are extremely fast as a result of increasing carrier frequency. The frequency may be as high as 20 kHz. Motors which are designed for low-voltage sinusoidal power run more efficiently and quieter under this condition. However, the insulation in small- and medium-size motors may experience undesirable stress,

  8. Surface plasmon polaritons on soft-boundary graphene nanoribbons and their application as voltage controlled plasmonic switches and frequency demultiplexers

    E-print Network

    Forati, Ebrahim

    2013-01-01

    A graphene sheet gated with a ridged ground plane, creating a soft-boundary (SB) graphene nanoribbon, is considered. By adjusting the ridge parameters and bias voltage a channel can be created on the graphene which can guide TM surface plasmon polaritons (SPP). Two types of modes are found; fundemental and higher-order modes with no apparent cutoff frequency and with energy distributed over the created channel, and edge modes with energy concen-trated at the soft-boundary edge. Dispersion curves, electric near-field patterns, and current distributions of these modes are determined. Since the location where energy is concentrated in the edge modes can be easily controlled electronically by the bias voltage and frequency, the edge-mode phenomena is used to propose a novel voltage controlled plasmonic switch and a plasmonic frequency demultiplexer.

  9. 612 IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS, VOL. 44, NO. 5, OCTOBER 1997 A Series Active Power Filter Based on a Sinusoidal

    E-print Network

    Catholic University of Chile (Universidad Católica de Chile)

    Filter Based on a Sinusoidal Current-Controlled Voltage-Source Inverter Juan W. Dixon, Senior Member working as a sinusoidal current source, in phase with the mains voltage, has been devel- oped and tested, series active filters working as controllable voltage sources have been proposed [5]. With this approach

  10. Energy efficient ECS powered by a variable voltage/variable frequency power system

    SciTech Connect

    Cronin, M. J.

    1985-10-15

    The invention is an ECS system designed to utilize an induction motor and a cabin compressor for providing pressurized air that serves as a source of energy for heating, cooling, pressurizing and other air needs of modern aircraft. An aircraft engine driven generator, preferably a permanent-magnet generator (of the samarium-cobalt, SmCo, type), furnishes variable-voltage/variable frequency, VV/VF, power to the motor. The electric motor itself in the preferred embodiment is a highly reliable squirrel-cage induction motor powered directly from the VV/VF supply, with the result that its speed is proportional to the generator frequency, which in turn is dependent on the aircraft engine speed. The main cabin compressor and a secondary (auxiliary) supercharging compressor are both mounted on the motor shaft. The motor-compressor configuration is further characterized in that the ac motor has pole-changing winding (typically two), which permits two speed operation, while the cabin compressor is provided with inlet guide vanes. The interactive combination of these two features makes it possible to furnish the requisite air mass flow and pressurization levels over the conditions of variable air density and variable atmospheric pressure, as the airplane operates throughout its flight envelope.

  11. Energy efficient ECS powered by a variable voltage/variable frequency power system

    SciTech Connect

    Cronin, M.J.

    1984-07-31

    The invention is an ECS system designed to utilize an induction motor and a cabin compressor for providing pressurized air that serves as a source of energy for heating, cooling, pressurizing and other air needs of modern aircraft. An aircraft engine driven generator, preferably a permanent-magnet generator (of the samarium-cobalt, SmCo, type), furnishes variable-voltage/variable frequency, VV/VF, power to the motor. The electric motor itself in the preferred embodiment is a highly reliable squirrel-cage induction motor powered directly from the VV/VF supply, with the result that its speed is proportional to the generator frequency, which in turn is dependent on the aircraft engine speed. The main cabin compressor and a secondary (auxiliary) supercharging compressor are both mounted on the motor shaft. The motor-compressor configuration is further characterized in that the ac motor has pole-changing winding (typically two), which permits two speed operation, while the cabin compressor is provided with inlet guide vanes. The interactive combination of these two features makes it possible to furnish the requisite air mass flow and pressurization levels over the conditions of variable air density and variable atmospheric pressure, as the airplane operates throughout its flight envelope.

  12. Force sensor characterization under sinusoidal excitations.

    PubMed

    Medina, Nieves; de Vicente, Jesús

    2014-01-01

    The aim in the current work is the development of a method to characterize force sensors under sinusoidal excitations using a primary standard as the source of traceability. During this work the influence factors have been studied and a method to minimise their contributions, as well as the corrections to be performed under dynamic conditions have been established. These results will allow the realization of an adequate characterization of force sensors under sinusoidal excitations, which will be essential for its further proper use under dynamic conditions. The traceability of the sensor characterization is based in the direct definition of force as mass multiplied by acceleration. To do so, the sensor is loaded with different calibrated loads and is maintained under different sinusoidal accelerations by means of a vibration shaker system that is able to generate accelerations up to 100 m/s2 with frequencies from 5 Hz up to 2400 Hz. The acceleration is measured by means of a laser vibrometer with traceability to the units of time and length. A multiple channel data acquisition system is also required to simultaneously acquire the electrical output signals of the involved instrument in real time. PMID:25290287

  13. Force Sensor Characterization Under Sinusoidal Excitations

    PubMed Central

    Medina, Nieves; de Vicente, Jesús

    2014-01-01

    The aim in the current work is the development of a method to characterize force sensors under sinusoidal excitations using a primary standard as the source of traceability. During this work the influence factors have been studied and a method to minimise their contributions, as well as the corrections to be performed under dynamic conditions have been established. These results will allow the realization of an adequate characterization of force sensors under sinusoidal excitations, which will be essential for its further proper use under dynamic conditions. The traceability of the sensor characterization is based in the direct definition of force as mass multiplied by acceleration. To do so, the sensor is loaded with different calibrated loads and is maintained under different sinusoidal accelerations by means of a vibration shaker system that is able to generate accelerations up to 100 m/s2 with frequencies from 5 Hz up to 2400 Hz. The acceleration is measured by means of a laser vibrometer with traceability to the units of time and length. A multiple channel data acquisition system is also required to simultaneously acquire the electrical output signals of the involved instrument in real time. PMID:25290287

  14. Optimal Estimation Of Voltage Phasors And Frequency Deviation Using Linear And Non-Linear Kalman Filtering: Theory And Limitations

    Microsoft Academic Search

    Adly Girgis; T. Daniel Hwang

    1984-01-01

    This paper presents two techniques for optimal tracking of power system voltage phasors and frequency deviation. The first technique is based on a two-state linear Kalman filter model. The second technique is based on a three-state extended Kalman filter model. In the latter the frequency deviation is considered a third state variable and is recursively computed on-line. It is shown

  15. Radio frequency cavity analysis, measurement, and calibration of absolute Dee voltage for K-500 superconducting cyclotron at VECC, Kolkata.

    PubMed

    Som, Sumit; Seth, Sudeshna; Mandal, Aditya; Paul, Saikat; Duttagupta, Anjan

    2013-02-01

    Variable Energy Cyclotron Centre has commissioned a K-500 superconducting cyclotron for various types of nuclear physics experiments. The 3-phase radio-frequency system of superconducting cyclotron has been developed in the frequency range 9-27 MHz with amplitude and phase stability of 100 ppm and ±0.2(0), respectively. The analysis of the RF cavity has been carried out using 3D Computer Simulation Technology (CST) Microwave Studio code and various RF parameters and accelerating voltages ("Dee" voltage) are calculated from simulation. During the RF system commissioning, measurement of different RF parameters has been done and absolute Dee voltage has been calibrated using a CdTe X-ray detector along with its accessories and known X-ray source. The present paper discusses about the measured data and the simulation result. PMID:23464200

  16. Low-voltage field emitter array cathode for high frequency applications

    SciTech Connect

    Hill, D.N.; Ohlinger, W.L.; Feeney, R.K. [Georgia Institute of Technology, Atlanta, GA (United States)] [and others] [Georgia Institute of Technology, Atlanta, GA (United States); and others

    1993-07-01

    The composite-based low voltage field emitter cathode offers distinct advantages for high-frequency applications. It is based on a directionally solidified ZrO{sub 2}{center_dot}Y{sub 2}O{sub 3}-W eutectic composite containing aligned, single-crystal tungsten fibers, {approx}500 nm in diameter, with spatial densities of 2-50 X 10{sup 6}/cm{sup 2}. The composite can be etched to form fibers of virtually any length with tip radii of 5-10 nm. A gridded structure can be formed around the fibers using a line-of-sight vapor deposition process. Because of the thickness of the composite chips used as the substrate (0.5 mm) and the high resistivity of the oxide matrix, the insulator film can be made extremely thin, thereby reducing the extractor aperture radius. Emission tests have verified this configuration results in measurably higher field enhancement values for the arrays. 11 refs., 9 figs.

  17. RF voltage modulation at discrete frequencies with applications to crystal channeling extraction

    SciTech Connect

    Gabella, W.; Rosenzweig, J. (California Univ., Los Angeles, CA (United States). Dept. of Physics); Kick, R. (Illinois Math and Science Academy, Aurora, Illinois (United States)); Peggs, S. (Fermi National Accelerator Lab., Batavia, IL (United States))

    1992-05-01

    RF voltage modulation at a finite number of discrete frequencies is described in a Hamiltonian resonance framework. The theory is applied to the problem of parasitic extraction of a fixed target beam from a high energy proton collider, using a bent crystal as a thin septum'' within an effective width of about one micron. Three modes of employment of discrete resonances are proposed.First, a single relatively strong static drive'' resonance may be used to excite a test proton so that it will penetrate deeply into the channeling crystal. Second, a moderately strong feed'' resonance with a ramped modulation tune may be used to adiabatically trap protons near the edge of the beam core, and transport them to the drive resonance. Third, several weak resonances may be overlapped to create a chaotic amplitude band, either to transport protons to the drive resonance, or to provide a pulse stretching'' buffer between a feed resonance and the drive resonance. Extraction efficiency is semi- quantitatively described in terms of characteristic penetration,'' depletion,'' and repetition'' times. simulations are used to quantitatively confirm the fundamental results of the theory, and to show that a prototypical extraction scheme using all three modes promises good extraction performance.

  18. High frequency input impedance modeling of low-voltage residential installations - influence on lightning overvoltage simulations results.

    PubMed

    Bassi, Welson

    2014-01-01

    The overvoltage level of a system is strongly dependent on the connected loads and with more precise models, better and more reliable simulation results are obtained. This paper presents the input impedance characteristics, measured over a wide range of frequencies, of various actual low-voltage residential installations. The measured frequency responses were fitted by effective RLC models and a general model was also developed. The range of frequencies considered in the study, nearly d.c. up to 5 MHz, allows the use of these models for lightning or switching studies. It is also presented overvoltage simulations, using different residential installations models presented in the paper, of a distribution network subjected to lightning surges on the medium voltage circuit. PMID:26034685

  19. Ground fault location on a transmission line using high frequency transient voltages

    NASA Astrophysics Data System (ADS)

    Almteiri, Haifaa Abdulla

    This thesis addresses two different problems in the location of ground faults on transmission lines. The first problem is related to the reflected waves which arise for near faults to the busses. The second problem is utilizing wavelet in some special studies that required the manual measurement for determining the time difference between two consecutives signals of initial waves. Novel method is presented by using traveling wave approach with no exploiting of reflected waves to overcome the aforementioned difficulties. A simple effective approach to accurately and rapidly obtain the ground fault location along a transmission line during fault transients is presented. The objective of the presented method is to eliminate the need to use the reflected in ground fault measurement especially for a case of one-end measurement where there is no synchronization required for initial signals at both sides. This is accomplished by developing a new automatic technique for the time measurement to determine the time difference between the initial waves of ground and aerial mode voltages. Proposed approach is implemented in different environments such as electromagnetic Transients Program ATP/EMTP and MATLAB. High voltage transmission system will be modeled and different ground faults will be generated at different locations in the entire length of the transmission line. Further, a study of different factors that may have a remarkable effect to the accuracy is obtained such as the fault resistance and fault type. Simulation results and further statistical analysis show high correlation between the actual and estimated fault locations for all the studied cases. An extended comparative study between former method of fault location and the proposed method is obtained for better understanding and pinpointing the difficulties concerning the accuracy and rapid fault computations. The proposed approach has added a main advantage of requiring high frequency transient fault signals only from one-end of the transmission line without exploiting the reflected waves generated from the fault point. Furthermore, its insensitivity to naturally occurring close in infeed reflected waves which results significant errors in fault location measurement. Such waves are overlapped with initial wave cause a difficulty to identify the time difference.

  20. Series resonant high-voltage PFM DC-DC converter with voltage multiplier based a two-step frequency switching control for medical-use X ray power generator

    Microsoft Academic Search

    Junming Sun; Hitoshi Konishi; Yoshio Ogino; Enhui Chu; M. Nakaoka

    2000-01-01

    In general, high-voltage DC power supplies employing a variety of high-frequency inverters are implemented for constant value control schemes. In particular, their good transient and steady-state performances can not be achieved under wide load variations for a medical-use high voltage X ray generator ranging from 20 kV to 150 kV in the output voltage and from 0.5 mA to 1250

  1. The sinusoid and the phasor

    E-print Network

    Kushal Shah; Harishankar Ramachandran

    2010-06-10

    Mathieu equation is widely used to study several natural phenomenon. In this paper, we show that replacing the sinusoid in the Mathieu equation with a phasor can lead to solutions that behave in a totally different way. Solutions of Mathieu equation are either bounded or grow unboundedly at an exponential rate. Solutions of this new equation are always unbounded and grow linearly with time.

  2. The Effect of High Voltage, High Frequency Pulsed Electric Field on Slain Ovine Cortical Bone

    PubMed Central

    Asgarifar, Hajarossadat; Oloyede, Adekunle; Zare, Firuz

    2014-01-01

    High power, high frequency pulsed electric fields known as pulsed power (PP) has been applied recently in biology and medicine. However, little attention has been paid to investigate the application of pulse power in musculoskeletal system and its possible effect on functional behavior and biomechanical properties of bone tissue. This paper presents the first research investigating whether or not PP can be applied safely on bone tissue as a stimuli and what will be the possible effect of these signals on the characteristics of cortical bone by comparing the mechanical properties of this type of bone pre and post expose to PP and in comparison with the control samples. A positive buck-boost converter was applied to generate adjustable high voltage, high frequency pulses (up to 500 V and 10 kHz). The functional behavior of bone in response to pulse power excitation was elucidated by applying compressive loading until failure. The stiffness, failure stress (strength) and the total fracture energy (bone toughness) were determined as a measure of the main bone characteristics. Furthermore, an ultrasonic technique was applied to determine and comprise bone elasticity before and after pulse power stimulation. The elastic property of cortical bone samples appeared to remain unchanged following exposure to pulse power excitation for all three orthogonal directions obtained from ultrasonic technique and similarly from the compression test. Nevertheless, the compressive strength and toughness of bone samples were increased when they were exposed to 66 h of high power pulsed electromagnetic field compared to the control samples. As the toughness and the strength of the cortical bone tissue are directly associated with the quality and integrity of the collagen matrix whereas its stiffness is primarily related to bone mineral content these overall results may address that although, the pulse power stimulation can influence the arrangement or the quality of the collagen network causing the bone strength and toughness augmentation, it apparently did not affect the mineral phase of the cortical bone material. The results also confirmed that the indirect application of high power pulsed electric field at 500 V and 10 kHz through capacitive coupling method was safe and did not destroy the bone tissue construction. PMID:24761375

  3. A model for determining the induced voltage at the terminals of a pacemaker exposed to a low frequency magnetic field.

    PubMed

    Andretzko, J P; Hedjiedj, A; Guendouz, L

    2008-09-01

    This paper presents a method for calculating induced voltage, in vitro, at the terminals of a unipolar pacemaker (PM) subjected to a low frequency magnetic field. We propose a theoretical model which has been experimentally verified by using a homogeneous phantom model placed at the centre of the source generating a homogeneous magnetic field. The levels of the magnetic field used in our experiment are in accordance with the European Directive 2004/40/EC, which sets the occupational electromagnetic field exposure limits. The voltage induced at the terminals of an implanted pacemaker results in the superimposition of two different voltage sources. The first is due to the presence of the loop formed by the PM system and the second is due to the induced currents circulating in the coupling medium. The influence of the induced currents, calculated by the impedance method, is weak compared to the voltage of the loop. The theoretical results obtained agree with the experimental value. Thus, the proposed model can be used to predict the behaviour of a pacemaker subjected to a low frequency magnetic field as well as to those fields within the accepted exposure limits for a patient with a pacemaker. PMID:18784392

  4. Novel PWM scheme to control neutral point voltage variation in three-level voltage source inverter

    Microsoft Academic Search

    K. R. M. N. Ratnayake; Y. Murai; T. Watanabe

    1999-01-01

    This paper proposes a simple PWM scheme which alleviates the neutral point voltage fluctuation problem of the three level inverter applications. The new scheme employs modified version of well known multi-level sinusoidal pulse width modulation (SPWM) scheme. This modification shows a great potential of reducing neutral point voltage fluctuation and retained better sinusoidal shape at the output. This method avoids

  5. Developing reconfigurable FIFOs to optimize power\\/performance of Voltage\\/Frequency Island-based networks-on-chip

    Microsoft Academic Search

    Amir-Mohammad Rahmani; Pasi Liljeberg; Juha Plosila; Hannu Tenhunen

    2010-01-01

    Network-on-chip architectures partitioned into several Voltage\\/Frequency Islands (VFIs) have been proposed to alleviate problems related to integration, excessive energy consumption and clock distribution. The architecture is composed of synchronous switches that communicate with each other using bi-synchronous FIFOs. However, these FIFOs are not needed if adjacent switches belong to the same clock domain. In this paper, a Reconfigurable Synchronous\\/Bi-Synchronous (RSBS)

  6. Hot-Carrier- and Constant-Voltage-Stress-Induced Low-Frequency Noise in Nitrided High Dielectric MOSFETs

    Microsoft Academic Search

    M. Shahriar Rahman; Tanvir Hasan Morshed; Zeynep Celik-Butler; M. A. Quevedo-Lopez; A. Shanware; Luigi Colombo

    2009-01-01

    Understanding and minimization of low-frequency noise (LFN) originating from high- k (HK) gate dielectrics in new generation MOSFETs are of critical importance to applications in RF, analog, and digital circuits. To understand the effect of stress conditions on noise, nMOSFETs were subjected to accelerated hot-carrier stress (HCS) and positive constant-voltage stress (CVS). The additional LFN introduced through stressing was evaluated

  7. Sinusoidal reaction formulation for radiation and scattering from conducting surfaces

    NASA Technical Reports Server (NTRS)

    Richmond, J. H.; Wang, N.

    1974-01-01

    The piecewise-sinusoidal reaction technique was developed for low-frequency scattering and radiation from perfectly conducting bodies of arbitrary shape. The theory and numerical results for scattering patterns of rectangular plates and radiation patterns of corner-reflector antennas are presented.

  8. Estimating the parameters of exponentially damped sinusoids and pole-zero modeling in noise

    Microsoft Academic Search

    RAMDAS KUMARESAN; DONALD W. TUFTS

    1982-01-01

    We have presented techniques [1] - [6] based on linear prediction (LP) and singular value decomposition (SVD) for accurate estimation of closely spaced frequencies of sinusoidal signals in noise. In this note we extend these techniques to estimate the parameters of exponentially damped sinusoidal signals in noise. The estimation procedure presented here makes use of \\

  9. PARAMETER ESTIMATION OF THE EXPONENTIALLY DAMPED SINUSOID FOR NOISY SIGNALS

    SciTech Connect

    Pelaia II, Tom [ORNL

    2013-01-01

    The damped sinusoid equation is a common model for many scientific processes involving damped periodic signals. Here we present two methods for estimating the damped sinusoid parameters for noisy signals. Both methods are based upon an exact, closed form solution to fit the parameters for signals without noise, and they estimate the parameters for the noisy signals by the statistical maximum likelihood criterion. The first method relies on an optimizer to minimize the mean square signal error. The second method estimates the parameters by direct calculation and is suitable when the signal noise is small and the frequencies are sufficiently far from the integer and half integer values.

  10. Low-voltage polyphasic circuits

    NASA Astrophysics Data System (ADS)

    Baird, William H.; Jaynes, Michael L.

    2010-05-01

    Experimentation with polyphasic voltages is greatly simplified when microcontrollers are used to generate multiple square waves with fixed phase offsets. Each square wave is sent through a simple second-order Sallen-Key filter to produce an approximately sinusoidal voltage signal. The microcontroller allows the reproduction of split-phase and three-phase voltage relationships, mirroring those commonly distributed on the North American power grid, at safe voltage levels.

  11. Design of a constant-voltage and constant-current controller with dual-loop and adaptive switching frequency control

    NASA Astrophysics Data System (ADS)

    Yingping, Chen; Zhiqian, Li

    2015-05-01

    A 5.0-V 2.0-A flyback power supply controller providing constant-voltage (CV) and constant-current (CC) output regulation without the use of an optical coupler is presented. Dual-close-loop control is proposed here due to its better regulation performance of tolerance over process and temperature compared with open loop control used in common. At the same time, the two modes, CC and CV, could switch to each other automatically and smoothly according to the output voltage level not sacrificing the regulation accuracy at the switching phase, which overcomes the drawback of the digital control scheme depending on a hysteresis comparator to change the mode. On-chip compensation using active capacitor multiplier technique is applied to stabilize the voltage loop, eliminate an additional package pin, and save on the die area. The system consumes as little as 100 mW at no-load condition without degrading the transient response performance by utilizing the adaptive switching frequency control mode. The proposed controller has been implemented in a commercial 0.35-?m 40-V BCD process, and the active chip area is 1.5 × 1.0 mm2. The total error of the output voltage due to line and load variations is less than ±1.7%.

  12. New soft-switching phase-shifted PWM high-frequency inverter-linked cycloconverter incorporating voltage-clamped quasi-resonant technique

    Microsoft Academic Search

    H. Yonemori; A. Chibani; M. Nakaoka

    1991-01-01

    A sinewave CVCF power conversion conditioning system (PCS) based on a high-frequency (HF)-isolated AC-link cycloconversion circuit using soft-switching phase-shifted PWM (PSM) and instantaneous voltage regulation schemes is presented. This advanced circuit topology of voltage-clamped quasi-resonant (QR) switch concept, which comprises two-cascaded power conversion stages operating under the principle of zero-voltage switching (ZVS), is introduced in order to minimize switching losses,

  13. Challenges and opportunities for multi-functional oxide thin films for voltage tunable radio frequency/microwave components

    NASA Astrophysics Data System (ADS)

    Subramanyam, Guru; Cole, M. W.; Sun, Nian X.; Kalkur, Thottam S.; Sbrockey, Nick M.; Tompa, Gary S.; Guo, Xiaomei; Chen, Chonglin; Alpay, S. P.; Rossetti, G. A.; Dayal, Kaushik; Chen, Long-Qing; Schlom, Darrell G.

    2013-11-01

    There has been significant progress on the fundamental science and technological applications of complex oxides and multiferroics. Among complex oxide thin films, barium strontium titanate (BST) has become the material of choice for room-temperature-based voltage-tunable dielectric thin films, due to its large dielectric tunability and low microwave loss at room temperature. BST thin film varactor technology based reconfigurable radio frequency (RF)/microwave components have been demonstrated with the potential to lower the size, weight, and power needs of a future generation of communication and radar systems. Low-power multiferroic devices have also been recently demonstrated. Strong magneto-electric coupling has also been demonstrated in different multiferroic heterostructures, which show giant voltage control of the ferromagnetic resonance frequency of more than two octaves. This manuscript reviews recent advances in the processing, and application development for the complex oxides and multiferroics, with the focus on voltage tunable RF/microwave components. The over-arching goal of this review is to provide a synopsis of the current state-of the-art of complex oxide and multiferroic thin film materials and devices, identify technical issues and technical challenges that need to be overcome for successful insertion of the technology for both military and commercial applications, and provide mitigation strategies to address these technical challenges.

  14. Challenges and opportunities for multi-functional oxide thin films for voltage tunable radio frequency/microwave components

    SciTech Connect

    Subramanyam, Guru, E-mail: gsubramanyam1@udayton.edu [Department of Electrical and Computer Engineering, University of Dayton, Dayton, Ohio 45469 (United States); Cole, M. W., E-mail: melanie.w.cole.civ@mail.mil [U.S. Army Research Laboratory, Weapons and Materials Research Directorate, Aberdeen Proving Ground, Maryland 21005 (United States); Sun, Nian X. [Department of Electrical and Computer Engineering, Northeastern University, Boston, Massachusetts 02115 (United States); Kalkur, Thottam S. [Department of Electrical and Computer Engineering, University of Colorado, Colorado Springs, Colorado 80918 (United States); Sbrockey, Nick M.; Tompa, Gary S. [Structured Materials Industries, Inc., Piscataway, New Jersey 08854 (United States); Guo, Xiaomei [Boston Applied Technologies, Inc., Woburn, Massachusetts 01801 (United States); Chen, Chonglin [Department of Physics and Astronomy, University of Texas, San Antonio, Texas 78249 (United States); Alpay, S. P.; Rossetti, G. A. [Institute of Materials Science and Materials Science and Engineering Program, University of Connecticut, Storrs, Connecticut 06269 (United States); Dayal, Kaushik [Mechanics, Materials and Computing, Civil and Environmental Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213 (United States); Chen, Long-Qing [Department of Materials Science and Engineering, Penn State University, University Park, Pennsylvania 16802 (United States); Schlom, Darrell G. [Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853 (United States); Kavli Institute at Cornell for Nanoscale Science, Ithaca, New York 14853 (United States)

    2013-11-21

    There has been significant progress on the fundamental science and technological applications of complex oxides and multiferroics. Among complex oxide thin films, barium strontium titanate (BST) has become the material of choice for room-temperature-based voltage-tunable dielectric thin films, due to its large dielectric tunability and low microwave loss at room temperature. BST thin film varactor technology based reconfigurable radio frequency (RF)/microwave components have been demonstrated with the potential to lower the size, weight, and power needs of a future generation of communication and radar systems. Low-power multiferroic devices have also been recently demonstrated. Strong magneto-electric coupling has also been demonstrated in different multiferroic heterostructures, which show giant voltage control of the ferromagnetic resonance frequency of more than two octaves. This manuscript reviews recent advances in the processing, and application development for the complex oxides and multiferroics, with the focus on voltage tunable RF/microwave components. The over-arching goal of this review is to provide a synopsis of the current state-of the-art of complex oxide and multiferroic thin film materials and devices, identify technical issues and technical challenges that need to be overcome for successful insertion of the technology for both military and commercial applications, and provide mitigation strategies to address these technical challenges.

  15. Voltage-dependent outer hair cell stereocilia stiffness at acoustic frequencies.

    PubMed

    Zhang, Ming; Surles, James G

    2008-05-28

    The aim of this report is to show the effects of voltage changes on stereocilia stiffness in mammalian outer hair cells (OHCs). With the OHC cuticular plate anchored at a microchamber tip, step voltage commands drove an OHC inside the microchamber to move freely while stereocilia were oscillated at 510 Hz by a constant fluid-jet force. With basolateral OHC depolarized and shortened, the amplitude of stereocilia motion was increased, suggesting a decrease in stereocilia stiffness. Such a decrease in stiffness may serve as an important adjusting factor inside the cochlear amplifying loop. PMID:18463501

  16. Induction generator produces constant-frequency voltage from variable-speed drive

    NASA Technical Reports Server (NTRS)

    Riaz, M.

    1970-01-01

    Two-stage polyphase generator is usable as induction motor operable over range of speeds while powered from constant frequency source. It requires neither slip rings nor special adjustable-frequency power supplies or external reactive sources.

  17. Strong Ionization Asymmetry in a Geometrically Symmetric Radio Frequency Capacitively Coupled Plasma Induced by Sawtooth Voltage Waveforms

    NASA Astrophysics Data System (ADS)

    Bruneau, Bastien; Gans, Timo; O'Connell, Deborah; Greb, Arthur; Johnson, Erik V.; Booth, Jean-Paul

    2015-03-01

    The ionization dynamics in geometrically symmetric parallel plate capacitively coupled plasmas driven by radio frequency tailored voltage waveforms is investigated using phase resolved optical emission spectroscopy (PROES) and particle-in-cell (PIC) simulations. Temporally asymmetric waveforms induce spatial asymmetries and offer control of the spatiotemporal dynamics of electron heating and associated ionization structures. Sawtooth waveforms with different rise and fall rates are employed using truncated Fourier series approximations of an ideal sawtooth. Experimental PROES results obtained in argon plasmas are compared with PIC simulations, showing excellent agreement. With waveforms comprising a fast voltage drop followed by a slower rise, the faster sheath expansion in front of the powered electrode causes strongly enhanced ionization in this region. The complementary waveform causes an analogous effect in front of the grounded electrode.

  18. Monitoring voltage and frequency in smart distribution grids. A case study on data compression and accessibility

    Microsoft Academic Search

    Mihaela M. Albu; Ralf Neurohr; Dan Apetrei; Ioan Silvas; Dumitru Federenciuc

    2010-01-01

    Synchronized measurements became recently an affordable tool ready to be implemented not only at transmission system level but also at distribution level, mostly in conjunction with the applicability of the smart grid approach. As a preliminary step of introducing PMUs on a larger scale, extensive measurements campaigns, primarily dedicated to power quality purposes, were conducted within medium and low voltage

  19. A New Low Voltage, Maintenance-Free, Cesium Beam Tube for a Frequency Standard

    Microsoft Academic Search

    H. Jumonji; K. Tanaka; J. Toyama; H. Takaoka; K. Kariya; J. Kawada

    1978-01-01

    The design and the pilot production of a newly developed cesium beam tube for the atomic standard are described and the performance data are presented. The elimination of the vac-ion pump and the electron multiplier, both of which conventional tubes essentially contain in the operation of the entire system with only low voltage supplies. The coaxially aligned new structure contributes

  20. High frequency finite element analysis of electromagnetic radiation due to partial discharges in high voltage equipment

    Microsoft Academic Search

    S. Xiao; P. J. Moore; M. D. Judd; I. E. Portugues

    2008-01-01

    Measuring partial discharge (PD) activity in high voltage plant is a well established technique used to monitor insulation integrity. A partial discharge is a surge of electrons within a dielectric due to ionisation caused by the electric field and it is a sign of insulation degradation or overstressing. The acceleration of electrons creates electromagnetic radiation. This paper studies the high

  1. Verification of voltage/frequency requirement for emergency diesel generator in nuclear power plant using dynamic modeling

    SciTech Connect

    Hur, Jin-Suk; Roh, Myung- Sub [KEPCO International Nuclear Graduate School, 1456-1 Shinam-ri, Seosaeng-myeon, Ulju-gun, Ulsan, 689-882 (Korea, Republic of)

    2014-02-12

    One major cause of the plant shutdown is the loss of electrical power. The study is to comprehend the coping action against station blackout including emergency diesel generator, sequential loading of safety system and to ensure that the emergency diesel generator should meet requirements, especially voltage and frequency criteria using modeling tool. This paper also considered the change of the sequencing time and load capacity only for finding electrical design margin. However, the revision of load list must be verified with safety analysis. From this study, it is discovered that new load calculation is a key factor in EDG localization and in-house capability increase.

  2. Verification of voltage/frequency requirement for emergency diesel generator in nuclear power plant using dynamic modeling

    NASA Astrophysics Data System (ADS)

    Hur, Jin-Suk; Roh, Myung-Sub

    2014-02-01

    One major cause of the plant shutdown is the loss of electrical power. The study is to comprehend the coping action against station blackout including emergency diesel generator, sequential loading of safety system and to ensure that the emergency diesel generator should meet requirements, especially voltage and frequency criteria using modeling tool. This paper also considered the change of the sequencing time and load capacity only for finding electrical design margin. However, the revision of load list must be verified with safety analysis. From this study, it is discovered that new load calculation is a key factor in EDG localization and in-house capability increase.

  3. A Space Vector PWM Scheme for Multifrequency Output Voltage Generation With Multiphase Voltage-Source Inverters

    Microsoft Academic Search

    Drazen Dujic; Gabriele Grandi; Martin Jones; Emil Levi

    2008-01-01

    Multiphase variable-speed drives, supplied from two-level voltage-source inverters (VSIs), are nowadays considered for various industrial applications. Depending on the drive structure and\\/or the motor design, the VSI is required to generate either sinusoidal voltages or voltages that contain a certain number of sinusoidal components (ldquomultifrequency output voltagesrdquo). The existing space vector pulsewidth-modulation (SVPWM) schemes are based on selection of (n-1)

  4. Development of a high frequency and high voltage pulse transformer for compact TWT HVPS

    Microsoft Academic Search

    S. C. Kim; D. T. Kim; G. M. Ha; S. H. Nam

    2003-01-01

    In designing a compact and high efficiency TWT microwave amplifier, the role of a high power density DC power supply is very important. In order to reduce the volume of the power supply, it is necessary to increase the switching frequency of the power supply. The high operation frequency mainly reduces the transformer volume in the power supply. However, a

  5. High-Frequency Stimulation Produces a Transient Blockade of Voltage-Gated Currents in Subthalamic Neurons

    E-print Network

    Cossart, Rosa

    tetanus, consist- ing of 100- s bipolar stimuli at a frequency of 100­250 Hz during 1 min, produced a full. Thus a high-frequency tetanus produces a blockade of the spontaneous activities of STN neurons) and its surgical destruction, both greatly ameliorate motor signs of Parkinson's disease in patients, led

  6. High-frequency voltage-controlled-oscillator for use with inverted- mesa quartz resonators

    SciTech Connect

    Wessendorf, K.O.

    1996-08-01

    An oscillator circuit has been developed that uses inverted mesa resonators, in a high precision VCO application, at frequencies historically dominated by SAW designs. This design incorporates a frequency tripler that provides a 600 MHz output capability using a 200 MHz 3{sup rd} overtone resonator. This design has advantages over equivalent SAW alternatives: lower power consumption, superior aging characteristics, linear frequency pulling and low frequency versus temperature sensitivity. The VCO presented demonstrates {gt} +/- 60 ppm pullability (0 to 7V control), tuning linearity better than +/- 5% with phase noise at 1 kHz {lt} -110 DBc/Hz. this oscillator- tripler exploits the nonlinear characteristics of an emitter-coupled pair differential amplifier to obtain a high performance oscillator design.

  7. A High-Frequency Resonant Inverter Topology With Low-Voltage Stress

    E-print Network

    Rivas, Juan M.

    This paper presents a new switched-mode resonant inverter, which we term the inverter, that is well suited to operation at very high frequencies and to rapid on/off control. Features of this inverter topology include low ...

  8. Sinusoidal voltage controlled oscillators using operational transconductance amplifiers 

    E-print Network

    Hoyle Passano, Javier Joaquin

    1985-01-01

    0. 8 0. 6 Nl 0. 4 0. 2 N5 -0. 2 0 12 VI V!M -0. 4 -0. 6 Figure S. S Nonlinear Characteristics of X~, Xs, JVs versus ~vr's V, The effect of the saturation characteristic is shown in Figure 3. 4, where for the fundamental components.... 4) then V~~f - V. a (3. 6) where s = ju Table 8. 2 X, ( v ? ) Values (viM) VALUES OF N. (i) 1 NI ? (sin ( ? )+( ? ) (1-( ? ) ) 2 - -I VIM VIM V IM 2 1T V. 1 V. 1 V. 1 N3 ( ( ? ) -I ) ( I-( ? ) ) 2 VIM VIM 2 VIM 2 tt V. V. 1 1 V. 1...

  9. Voltage Dependence of Subthreshold Resonance Frequency in Layer II of Medial Entorhinal Cortex

    E-print Network

    Hasselmo, Michael

    properties of individual neurons in ento- rhinal cortex (EC) may contribute to their functional properties in awake, behaving rats. Models propose that entorhinal grid cells could arise from shifts in the intrinsic frequency of neurons caused by changes in membrane potential owing to depolarizing input from neurons coding

  10. A novel soft-switched, high-frequency, high-efficiency, high-current 12 V voltage regulator-the phase-shift buck converter

    Microsoft Academic Search

    Jia Wei; Fred C. Lee

    2003-01-01

    This paper presents two novel soft-switched high-frequency high-efficiency, fast transient response 12 V voltage regulator (VR) topologies-the phase-shift buck (PSB) and the matrix-transformer phase-shift buck (MTPSB)-for high current applications. They improve efficiency at high switching frequencies and also feature very simple magnetic structures. For future high-frequency, high-current 12 V VRs, PSB and MTPSB converters are the cost-effective solutions. Experimental results

  11. Advanced soft-switching sinewave PWM high-frequency inverter-link cycloconverter incorporating voltage-clamped quasi-resonant and capacitive snubber techniques

    Microsoft Academic Search

    H. Yoneniori; M. Nakaoka

    1991-01-01

    An improved version of a sinewave CVCF power conversion conditioning system (PCS) which is based on a high-frequency (HF) transformer isolated-linked cycloconversion circuit incorporating soft-switching phase shifted PWM (PSM) principle and instantaneous voltage regulation strategy is discussed. This circuit topology and the modifications of the voltage-clamped quasi-resonant pole (QR-P) concept, which comprises inverter-cycloconverter cascaded power conversion stages operating under the

  12. A novel space-voltage vector modulated sinewave three-phase inverter with high-frequency transformer-coupled resonant DC link

    Microsoft Academic Search

    H. Yonemori; K. Hayashi; M. Nakaoka

    1994-01-01

    A novel type of quasi-resonant DC link (QRDCL) three-phase voltage-sourced inverter circuit topology operating under a commutation principle of the auxiliary high-frequency (HF) transformer-assisted zero voltage switching (ZVS)-PWM is presented. The basic operating principle of this power conversion circuit using auxiliary transformer-assisted QRDCL (TQRDCL) more suitable for CVCF\\/UPS, power active filter, switched-mode PWM converter, and new energy-interfaced power supplies for

  13. Stability of a cantilever beam with tip mass subject to axial sinusoidal excitations

    NASA Astrophysics Data System (ADS)

    Lee, H. P.

    1995-05-01

    The equation of motion of a cantilever beam with a tip mass subject to axial sinusoidal excitations at the clamped end is derived based on Hamilton's principle and the assumed mode method. The effects of axial sinusoidal excitation of the axial displacement, velocity or acceleration at the clamped end on the stability of the beam are then examined by using Bolotin's method. The respective regions of instability are determined by converting the resulting equations of boundary frequencies to the standard form of a generalized eigenvalue problem. Instability regions for various combinations of tip mass and amplitudes of the sinusoidal axial excitations in terms of displacement, velocity, and acceleration are presented.

  14. Frequency tuning in the electroreceptive periphery.

    PubMed Central

    Olson, E S; Smullin, L D

    1989-01-01

    Our studies are concerned with the frequency tuning that is provided by the electrical resonance of tuberous electroreceptors. Frequency selectivity had previously been measured in the electroreceptor's afferent fibers, and resonant conductances in the electroreceptor cell membrane had been implicated in producing the selectivity. With transdermal application of sinusoidal current, we measured the frequency dependence of the impedance of small areas of the electroreceptor/skin structure of the weakly electric fish Sternopygus and Eigenmannia, and used our data to make a quantitative linear model of the structure. The qualitative form of the model was proposed by Bennett (1). The quantitative model allows us to estimate the frequency selectivity of the voltage across the innervated membrane of the electroreceptor cells. The frequency selectivity of electroreceptor cell voltage derived from our data are as sharp as the neural selectivity at frequencies close to the most sensitive frequency. Many of our measurements supported the linear system model. However, spontaneous electroreceptor voltage oscillations were detected in some of our specimens, suggesting that the electroreceptors can operate in a regime of active nonlinearity. A simple explanation for the observed oscillations is that they arise when damping in the electroreceptor cell's resonant membrane is negative for a limited span of membrane voltage surrounding the resting voltage. The response of oscillating units to sinusoidal current was compatible with this explanation. We report experimental observations bearing on the consequences of active nonlinearity for the frequency tuning of a resonant system. Images FIGURE 11 FIGURE 4 FIGURE 5 FIGURE 6 FIGURE 11 FIGURE 12 PMID:2765655

  15. Digitally synthesized high purity, high-voltage radio frequency drive electronics for mass spectrometry.

    PubMed

    Schaefer, R T; MacAskill, J A; Mojarradi, M; Chutjian, A; Darrach, M R; Madzunkov, S M; Shortt, B J

    2008-09-01

    Reported herein is development of a quadrupole mass spectrometer controller (MSC) with integrated radio frequency (rf) power supply and mass spectrometer drive electronics. Advances have been made in terms of the physical size and power consumption of the MSC, while simultaneously making improvements in frequency stability, total harmonic distortion, and spectral purity. The rf power supply portion of the MSC is based on a series-resonant LC tank, where the capacitive load is the mass spectrometer itself, and the inductor is a solenoid or toroid, with various core materials. The MSC drive electronics is based on a field programmable gate array (FPGA), with serial peripheral interface for analog-to-digital and digital-to-analog converter support, and RS232/RS422 communications interfaces. The MSC offers spectral quality comparable to, or exceeding, that of conventional rf power supplies used in commercially available mass spectrometers; and as well an inherent flexibility, via the FPGA implementation, for a variety of tasks that includes proportional-integral derivative closed-loop feedback and control of rf, rf amplitude, and mass spectrometer sensitivity. Also provided are dc offsets and resonant dipole excitation for mass selective accumulation in applications involving quadrupole ion traps; rf phase locking and phase shifting for external loading of a quadrupole ion trap; and multichannel scaling of acquired mass spectra. The functionality of the MSC is task specific, and is easily modified by simply loading FPGA registers or reprogramming FPGA firmware. PMID:19044454

  16. Digitally synthesized high purity, high-voltage radio frequency drive electronics for mass spectrometry

    SciTech Connect

    Schaefer, R. T.; Mojarradi, M. [Advanced Computer Systems and Technologies Group, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109 (United States); MacAskill, J. A.; Chutjian, A.; Darrach, M. R.; Madzunkov, S. M. [Atomic and Molecular Physics Group, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109 (United States); Shortt, B. J. [Astrium Satellites Ltd., Gunnels Wood Road, Stevenage, Hertfordshire SG1 2AS (United Kingdom)

    2008-09-15

    Reported herein is development of a quadrupole mass spectrometer controller (MSC) with integrated radio frequency (rf) power supply and mass spectrometer drive electronics. Advances have been made in terms of the physical size and power consumption of the MSC, while simultaneously making improvements in frequency stability, total harmonic distortion, and spectral purity. The rf power supply portion of the MSC is based on a series-resonant LC tank, where the capacitive load is the mass spectrometer itself, and the inductor is a solenoid or toroid, with various core materials. The MSC drive electronics is based on a field programmable gate array (FPGA), with serial peripheral interface for analog-to-digital and digital-to-analog converter support, and RS232/RS422 communications interfaces. The MSC offers spectral quality comparable to, or exceeding, that of conventional rf power supplies used in commercially available mass spectrometers; and as well an inherent flexibility, via the FPGA implementation, for a variety of tasks that includes proportional-integral derivative closed-loop feedback and control of rf, rf amplitude, and mass spectrometer sensitivity. Also provided are dc offsets and resonant dipole excitation for mass selective accumulation in applications involving quadrupole ion traps; rf phase locking and phase shifting for external loading of a quadrupole ion trap; and multichannel scaling of acquired mass spectra. The functionality of the MSC is task specific, and is easily modified by simply loading FPGA registers or reprogramming FPGA firmware.

  17. IEEE SIGNAL PROCESSING LETTERS, VOL. 17, NO. 5, MAY 2010 461 Iterative Estimation of Sinusoidal Signal Parameters

    E-print Network

    Stylianou, Yannis

    been proposed. A simple and fast method for sinusoidal parameter estimation uses Fourier spectrum where be violated. Consequently, the frequency estimation provided by Fourier transform-based methods is rather of the sinusoidal components are unknown. Hence, the estimation procedure is usually split into two steps: i

  18. Frequency Modulation

    Microsoft Academic Search

    B. Van Der Pol

    1930-01-01

    The differential equation of a frequency modulated transmitter is considered and the expression of the current as a function of time is derived. Frequency analysis of this function is made for two specific cases, (A) sinusoidal frequency modulation (telephony) and (B), right-angle frequency modulation (telegraphy with \\

  19. Genetic-algorithm cancellation of sinusoidal powerline interference in electrocardiograms.

    PubMed

    Kumaravel, N; Nithiyanandam, N

    1998-03-01

    The paper describes a method, based on a genetic algorithm, to remove sinusoidal powerline interference in electrocardiograms. There is a report on the use of the genetic algorithm to remove powerline interference for two different types of interference, powerline interference with frequency drift, and interference with frequency drift as well as third- harmonic distortion. The studies are conducted on electrocardiograms with simulated interference and also on actual noisy electrocardiogram records. The results obtained using the genetic algorithm in these cases of interference are presented. PMID:9684459

  20. Dependence of sinusoidal electric field effect on neuronal morphological properties

    NASA Astrophysics Data System (ADS)

    Wei, Xile; Yin, Xiaowei; Lu, Meili; Yi, Guosheng; Wang, Jiang

    2015-04-01

    In this paper, the neuronal firing patterns under extracellular sinusoidal electric field (EF) are investigated based on a reduced two-compartment model with focus on the effects of morphological and internal coupling parameters. We observe that the neuron can exhibit bursting, synchronous firing and subthreshold oscillation depending on EF amplitude A and frequency f. Furthermore, neuronal firing properties change obviously over a range of morphological parameter p. As p increases, the firing region expands first and then diminishes gradually until it disappears in the observed (A, f) parameter space and the transition from bursting to synchronous firing is also markedly distinct. Meanwhile, the morphological parameter also has significant effects on the EF threshold for triggering neuronal spikes. Unlike morphological parameter, though the internal coupling conductance gc can also induce some changes in firing behavior and EF threshold, it cannot qualitatively change neuronal dynamical properties. All these results demonstrate that neuronal morphology plays a crucial role in neuronal responses to sinusoidal EF.

  1. A New High-Frequency Voltage Injection Method for Sensorless Drive of Permanent-Magnet Synchronous Motors with Pole Saliency

    NASA Astrophysics Data System (ADS)

    Shinnaka, Shinji

    This paper proposes a new sensorless vector control method for salient-pole permanent-magnet synchronous motors. In regard to rotor phase estimation, the sensorless vector control method is featured by a new high-frequency voltage injection method distinguished from the conventional ones by a unique ellipse shape of the spatially rotating, and by a new PLL method whose input is a high frequency current auto-correlated signal. The new vector control method established by two innovative technologies can have the following high-performance and attractive features: 1) it can allow 250% rated torque at standstill; 2) it can operate from zero to the rated speed under the rated motoring or regenerating load; 3) it accepts instant injection of the rated load even for zero-speed control; 4) it accommodates a load with huge moment of inertia; 5) phase estimation is very robust against inverter dead time; 6) computational load for estimating rotor phase is very small, would be the smallest among the methods with comparable performance. This paper presents the new vector control method by focusing on two innovative technologies from its principles to design rules. Usefulness of the new vector control method is verified through extensive experiments.

  2. Galalctic Tides & the Sinusoidal Potential

    NASA Astrophysics Data System (ADS)

    Bartlett, David F.

    2011-05-01

    The sinusoidal potential is a nonNewtonian alternative to dark matter. Instead of ? = -GM/r we write ? = -(GM/r) cos kor, where ko= 2?/ ?o and ?o = Ro/20= 400 pc. Evidence for this choice for the "wavelength” ?o has been given in one article and many previous meetings of the AAS & DDA. The solar system and nearby stars are trapped in a local groove of width ?r < 400 pc. The rapid alternation of attraction and repulsion within the groove gives very strong Galactic radial tides. The epicyclic period is only 7 Myr . The Keplerian period for comets in the middle of the Oort cloud is also 7 Myr. The 1:1 resonance between material in the groove and the cloud provides a new mechanism for filling the Oort cloud. The Oort cloud is emptied by the same strong radial tides. Evidence is found in the 499 comets with calculated 1/aoriginal in the latest Catalogue of Cometary Orbits (Marsden & Williams 2008). . I separate the comets into 12 classes on the basis of Quality (4 types) and semi-major axis aoriginal . For 10 of the 12 classes radial tides dominate Z-tides. The classic Oort cloud comets (1851-1996) have a particularly strong modulation with galactic longitude. This modulation is exactly in those directions where a radial tide would be important. The equally numerous recent Oort comets (1996-2008) show a different evidence for strong radial tides. The recent comets generally have much larger perihelion distances q than the classic ones. Here the evidence is that a radial tide is removing angular momentum from the orbit and thus bringing the perihelion closer to the earth and to observers.

  3. One-dimensional plasma photonic crystals with sinusoidal densities

    SciTech Connect

    Qi, L., E-mail: qilimei1204@163.com; Shang, L.; Zhang, S. [College of Physics and Engineering, Qufu Normal University, No. 57, West Jingxuan Road, Qufu 273165 (China)] [College of Physics and Engineering, Qufu Normal University, No. 57, West Jingxuan Road, Qufu 273165 (China)

    2014-01-15

    Properties of electromagnetic waves with normal and oblique incidence have been studied for one-dimensional plasma layers with sinusoidal densities. Wave transmittance as a function of wave frequency exhibits photonic band gaps characteristic of photonic crystals. For periodic structures, increasing collision frequency is demonstrated to lead to greater absorption, increasing the modulation factor enlarges the gap width, and increasing incidence angle can change the gap locations of the two polarizations. If a defect layer is introduced by inserting a new plasma layer in the center, a defect mode may appear within the gap. Periodic number, collision frequency, and modulation factor can affect magnitude of the defect mode. The incidence angle enables the frequency to be tuned. Defect layer thickness affects both frequency and number of defect modes. These results may provide theoretical guidance in designing tunable narrow-band filters.

  4. The Application of Auto-Disturbance Rejection Control Optimized by Least Squares Support Vector Machines Method and Time-Frequency Representation in Voltage Source Converter-High Voltage Direct Current System

    PubMed Central

    Gao, Zhong-Ke

    2015-01-01

    In order to improve the performance of voltage source converter-high voltage direct current (VSC-HVDC) system, we propose an improved auto-disturbance rejection control (ADRC) method based on least squares support vector machines (LSSVM) in the rectifier side. Firstly, we deduce the high frequency transient mathematical model of VSC-HVDC system. Then we investigate the ADRC and LSSVM principles. We ignore the tracking differentiator in the ADRC controller aiming to improve the system dynamic response speed. On this basis, we derive the mathematical model of ADRC controller optimized by LSSVM for direct current voltage loop. Finally we carry out simulations to verify the feasibility and effectiveness of our proposed control method. In addition, we employ the time-frequency representation methods, i.e., Wigner-Ville distribution (WVD) and adaptive optimal kernel (AOK) time-frequency representation, to demonstrate our proposed method performs better than the traditional method from the perspective of energy distribution in time and frequency plane. PMID:26098556

  5. Design and Operation of 6-bit, 0.25-mVpp Quasi-sine Voltage Waveform Generator based on SFQ Pulse-frequency Modulation

    NASA Astrophysics Data System (ADS)

    Takahashi, Yoshitaka; Shimada, Hiroshi; Maezawa, Masaaki; Mizugaki, Yoshinao

    A digital-to-analogue converter (DAC) consisting of single-flux-quantum (SFQ) circuitry is known to generate accurate analogue voltages defined by the Josephson relationship. We have been developing SFQ-DACs of the pulse-frequency modulation (PFM) type. Toward voltage standard applications of SFQ-DACs, we have set the target values for the voltage amplitude and resolution at 20 mVpp and 10 bits, respectively. So far, we have reported a 5-bit, 10-?Vpp quasi-sine voltage waveform generator comprising a PFM-type SFQ-DAC integrated with an on-chip digital code generator. Its small peak-to-peak voltage amplitude was due to the lack of an on-chip voltage multiplier (VM). In this paper, we present a 6-bit, 0.25-mVpp quasi-sine voltage waveform generator integrated with a 10-fold VM. The resolution is improved by introducing efficient logic sequences into the SFQ-DAC.

  6. I Found Sinusoids in My Gas Bill.

    ERIC Educational Resources Information Center

    Schloemer, Cathy G.

    2000-01-01

    Uses the average-monthly-temperature function as an application of the sine wave. Argues that the attractive aspect of gas bill graphs is that they clearly illustrate that sinusoidal curves are useful and meaningful in an everyday context. (ASK)

  7. Parametric Estimation of Harmonically Related Sinusoids 

    E-print Network

    Dixit, Richa

    2010-04-01

    the signal, the noise parameters have to be tracked accurately in real time. There are well established parametric estimation techniques for determining various parameters of independent sinusoids. The iterative methods based on the linear prediction...

  8. A Divided Voltage Half-Bridge High Frequency Soft-Switching PWM DC-DC Converter with High and Low Side DC Rail Active Edge Resonant Snubbers

    Microsoft Academic Search

    Khairy Fathy; Keiki Morimoto; Toshimitsu Doi; Hiroyuki Ogiwara; Hyun Woo Lee; Mutsuo Nakaoka

    2006-01-01

    This paper presents a new circuit topology of dc bus line switch-assisted half-bridge soft switching PWM inverter type dc-dc converter for arc welder. The proposed power converter is composed of typical voltage source half-bridge high frequency PWM inverter with a high frequency transformer link in addition to dc bus line side power semiconductor switching devices for PWM control scheme and

  9. Voltage-Source Series Resonant Zero Current Soft Switching High-Frequency Inverter with PDM Scheme for Induction Heating Roller in Copy Machine

    Microsoft Academic Search

    Yuelu Feng; Mutsuo Nakaoka

    2004-01-01

    This paper presents a voltage source half bridge series load resonant ZCS-PDM high frequency inverter using IGBT power module for the induction-heating roller in copy machines. The steady-state operating principle and unique features of this high frequency inverter with two ZCS-assisted inductive snubbers in series with the active power switch are presented, which can achieve stable zero current soft commutation

  10. A special high-frequency soft-switched high-voltage isolated DC\\/DC power supply for multiple GCT gate drivers

    Microsoft Academic Search

    Jahangir Afsharian; Navid Zaragari; Bin Wu

    2010-01-01

    This paper is devoted to the development of a novel high voltage isolated power supply for the gate driver of integrated Gate Commutated Thyristors (GCT). The proposed power supply is essentially a special high frequency soft switched DC\\/DC converter, integrating six parallel isolated power supplies (PIPS) in one module where each power supply generates a regulated dc supply for the

  11. Optimal Energy Saving Control of Induction Motors Fed by Variable-Voltage and Variable-Frequency Source for Refrigeration and Air Conditioning Systems

    Microsoft Academic Search

    Juh-Shinun Lin

    It is well known that the axial power of an air conditioning system is proportional to the cubic power of the motor speed. This paper is concerned with the determination and experiment of the input voltage and frequency for the optimal efficiency operation of induction motors which drive the air handing unit blower, the cooling tower fan and the chiller

  12. A Framework of Concurrent Task Scheduling and Dynamic Voltage and Frequency Scaling in Real-Time Embedded Systems with Energy Harvesting

    E-print Network

    Pedram, Massoud

    achieve full energy autonomy (i.e., perpetual, battery-free operation) of a real-time embedded system loop performing real-time task scheduling and setting the voltage and frequency level in the embedded, photovoltaic, real-time embedded system, supercapacitor 1. Introduction Minimizing power consumption remains

  13. Design of Asymptotically Convergent Frequency Estimator Using Contraction Theory

    Microsoft Academic Search

    B. B. Sharma; I. N. Kar

    2008-01-01

    The problem of estimating unknown frequencies of a sinusoidal signal simultaneously is a classical problem in signal and system theory. Many approaches and algorithms are proposed in literature to develop estimators for a measurable sinusoidal signal having multiple sinusoids with unknown amplitudes, frequencies and phases. In this work, an asymptotically convergent frequency estimator is given for estimation of n-unknown frequencies

  14. Characteristics of temperature rise in variable inductor employing magnetorheological fluid driven by a high-frequency pulsed voltage source

    NASA Astrophysics Data System (ADS)

    Lee, Ho-Young; Kang, In Man; Shon, Chae-Hwa; Lee, Se-Hee

    2015-05-01

    A variable inductor with magnetorheological (MR) fluid has been successfully applied to power electronics applications; however, its thermal characteristics have not been investigated. To evaluate the performance of the variable inductor with respect to temperature, we measured the characteristics of temperature rise and developed a numerical analysis technique. The characteristics of temperature rise were determined experimentally and verified numerically by adopting a multiphysics analysis technique. In order to accurately estimate the temperature distribution in a variable inductor with an MR fluid-gap, the thermal solver should import the heat source from the electromagnetic solver to solve the eddy current problem. To improve accuracy, the B-H curves of the MR fluid under operating temperature were obtained using the magnetic property measurement system. In addition, the Steinmetz equation was applied to evaluate the core loss in a ferrite core. The predicted temperature rise for a variable inductor showed good agreement with the experimental data and the developed numerical technique can be employed to design a variable inductor with a high-frequency pulsed voltage source.

  15. Collector optimization for tradeoff between breakdown voltage and cut-off frequency in SiGe HBT

    NASA Astrophysics Data System (ADS)

    Fu, Qiang; Zhang, Wan-Rong; Jin, Dong-Yue; Ding, Chun-Bao; Zhao, Yan-Xiao; Lu, Dong

    2014-11-01

    As is well known, there exists a tradeoff between the breakdown voltage BVCEO and the cut-off frequency fT for a standard heterojunction bipolar transistor (HBT). In this paper, this tradeoff is alleviated by collector doping engineering in the SiGe HBT by utilizing a novel composite of P+ and N? doping layers inside the collector-base (CB) space-charge region (SCR). Compared with the single N-type collector, the introduction of the thin P+ layers provides a reverse electric field weakening the electric field near the CB metallurgical junction without changing the field direction, and the thin N? layer further effectively lowers the electric field near the CB metallurgical junction. As a result, the electron temperature near the CB metallurgical junction is lowered, consequently suppressing the impact ionization, thus BVCEO is improved with a slight degradation in fT. The results show that the product of fT × BVCEO is improved from 309.51 GHz·V to 326.35 GHz·V.

  16. An algorithm for the evaluation of induced transition probabilities for non-sinusoidal and sinusoidal applied fields with an application to Gaussian pulses

    Microsoft Academic Search

    G. F. Thomas; W. J. Meath

    1983-01-01

    An efficient computational algorithm for evaluating the evolution operator, and related induced transition probabilities, for a multilevel system interacting with an amplitude-modulated sinusoidal field of arbitrary strength, modulating envelope, frequency and phase, is developed. The algorithm is based on the Riemann product integral representation of the evolution operator in conjunction with Frazer's method of mean coefficients and avoids the introduction

  17. Analysis of a modular generator for high-voltage, high-frequency pulsed applications, using low voltage semiconductors (< 1 kV) and series connected step-up (1:10) transformers.

    PubMed

    Redondo, L M; Fernando Silva, J; Margato, E

    2007-03-01

    This article discusses the operation of a modular generator topology, which has been developed for high-frequency (kHz), high-voltage (kV) pulsed applications. The proposed generator uses individual modules, each one consisting of a pulse circuit based on a modified forward converter, which takes advantage of the required low duty cycle to operate with a low voltage clamp reset circuit for the step-up transformer. This reduces the maximum voltage on the semiconductor devices of both primary and secondary transformer sides. The secondary winding of each step-up transformer is series connected, delivering a fraction of the total voltage. Each individual pulsed module is supplied via an isolation transformer. The assembled modular laboratorial prototype, with three 5 kV modules, 800 V semiconductor switches, and 1:10 step-up transformers, has 80% efficiency, and is capable of delivering, into resistive loads, -15 kV1 A pulses with 5 micros width, 10 kHz repetition rate, with less than 1 micros pulse rise time. Experimental results for resistive loads are presented and discussed. PMID:17411205

  18. A novel transient rotor current control scheme of a doubly-fed induction generator equipped with superconducting magnetic energy storage for voltage and frequency support

    NASA Astrophysics Data System (ADS)

    Shen, Yang-Wu; Ke, De-Ping; Sun, Yuan-Zhang; Daniel, Kirschen; Wang, Yi-Shen; Hu, Yuan-Chao

    2015-07-01

    A novel transient rotor current control scheme is proposed in this paper for a doubly-fed induction generator (DFIG) equipped with a superconducting magnetic energy storage (SMES) device to enhance its transient voltage and frequency support capacity during grid faults. The SMES connected to the DC-link capacitor of the DFIG is controlled to regulate the transient dc-link voltage so that the whole capacity of the grid side converter (GSC) is dedicated to injecting reactive power to the grid for the transient voltage support. However, the rotor-side converter (RSC) has different control tasks for different periods of the grid fault. Firstly, for Period I, the RSC injects the demagnetizing current to ensure the controllability of the rotor voltage. Then, since the dc stator flux degenerates rapidly in Period II, the required demagnetizing current is low in Period II and the RSC uses the spare capacity to additionally generate the reactive (priority) and active current so that the transient voltage capability is corroborated and the DFIG also positively responds to the system frequency dynamic at the earliest time. Finally, a small amount of demagnetizing current is provided after the fault clearance. Most of the RSC capacity is used to inject the active current to further support the frequency recovery of the system. Simulations are carried out on a simple power system with a wind farm. Comparisons with other commonly used control methods are performed to validate the proposed control method. Project supported by the National Natural Science Foundation of China (Grant No. 51307124) and the Major Program of the National Natural Science Foundation of China (Grant No. 51190105).

  19. Generalized frequency modulation

    E-print Network

    Torres, Wade Patrick

    2001-01-01

    In frequency modulation (FM) systems, a continuous-time information signal is modulated onto a sinusoidal carrier wave by using the information signal to modulate the frequency of the carrier wave. In this thesis, a more ...

  20. The frequency behavior of InGaAs-AlInAs metal-semiconductor-metal photodetectors at low bias voltages for data communication applications

    Microsoft Academic Search

    J. H. Burroughes; M. S. Milshtein; G. D. Pettit; N. Pakdaman; H. Heinrich; J. M. Woodall

    1992-01-01

    The authors have fabricated lattice matched InGaAs\\/AlInAs metal-semiconductor-metal photodetectors on InP. The detectors have very low dark currents, low capacitance, and good responsivity, corresponding to at least 95% internal collection efficiency. It is demonstrated that multigigahertz bandwidths, as measured in the frequency domain, are achievable at typical logic-level bias voltages, and that therefore these detectors are viable candidates for long-wavelength

  1. Effective transformation of the energy of high-voltage pulses into high-frequency oscillations using a saturated-ferrite-loaded transmission line

    Microsoft Academic Search

    V. P. Gubanov; A. V. Gunin; O. B. Koval’chuk; V. O. Kutenkov; I. V. Romanchenko; V. V. Rostov

    2009-01-01

    A new method of converting a high-voltage video pulse into high-frequency oscillations using a nonlinear transmission line\\u000a with temporal dispersion has been studied. The dispersion was provided by pulsed magnetization reversal in a ferrite, which\\u000a was initially magnetized to saturation in an external magnetic field. For a 9-ns pulse, an average energy conversion efficiency\\u000a of about 10% was achieved. It

  2. Voltage-Source Series Resonant Zero Current Soft Switching High-Frequency Inverter with PDM Scheme for Induction Heating Roller in Copy Machine

    NASA Astrophysics Data System (ADS)

    Feng, Yuelu; Nakaoka, Mutsuo

    This paper presents a voltage source half bridge series load resonant ZCS-PDM high frequency inverter using IGBT power module for the induction-heating roller in copy machines. The steady-state operating principle and unique features of this high frequency inverter with two ZCS-assisted inductive snubbers in series with the active power switch are presented, which can achieve stable zero current soft commutation under pulse density modulated power regulation scheme. The experimental results of cost effective ZCS-PDM inverter treated here are evaluated on basis of computer simulation ones and discussed for the induction-heating roller from a practice point of view

  3. Riding the Ferris Wheel: A Sinusoidal Model

    ERIC Educational Resources Information Center

    Mittag, Kathleen Cage; Taylor, Sharon E.

    2011-01-01

    When thinking of models for sinusoidal waves, examples such as tides of the ocean, daily temperatures for one year in your town, light and sound waves, and certain types of motion are used. Many textbooks [1, p. 222] also present a "Ferris wheel description problem" for students to work. This activity takes the Ferris wheel problem out of the…

  4. Studies on frequency and gate voltage effects on the dielectric properties of Au/n-Si (110) structure with PVA-nickel acetate composite film interfacial layer

    NASA Astrophysics Data System (ADS)

    Tunç, T.; Gökçen, M.; Uslu, ?.

    2012-11-01

    The admittance technique was used in order to investigate the frequency dependence of dielectric constant ( ?'), dielectric loss ( ??), dielectric loss tangent (tan ?), the ac electrical conductivity ( ? ac), and the electric modulus of PVA (Ni-doped) structure. Experimental results revealed that the values of ?' , ??, (tan ?), ? ac and the electric modulus show fairly large frequency and gate bias dispersion due to the interface charges and polarization. The ? ac is found to increase with both increasing frequency and voltage. It can be concluded that the interface charges and interfacial polarization have strong influence on the dielectric properties of metal-polymer-semiconductor (MIS) structures especially at low frequencies and in depletion and accumulation regions. The results of this study indicate that the ?' values of Au/PVA/n-Si with Nickel-doped PVA interfacial layer are quite higher compared to those with pure and other dopant/mixture's of PVA.

  5. Connecting Renewables Directly to the Grid: Resilient Multi-Terminal HVDC Networks with High-Voltage High-Frequency Electronics

    SciTech Connect

    None

    2012-01-23

    GENI Project: GE is developing electricity transmission hardware that could connect distributed renewable energy sources, like wind farms, directly to the grid—eliminating the need to feed the energy generated through intermediate power conversion stations before they enter the grid. GE is using the advanced semiconductor material silicon carbide (SiC) to conduct electricity through its transmission hardware because SiC can operate at higher voltage levels than semiconductors made out of other materials. This high-voltage capability is important because electricity must be converted to high-voltage levels before it can be sent along the grid’s network of transmission lines. Power companies do this because less electricity is lost along the lines when the voltage is high.

  6. REVIEW OF SCIENTIFIC INSTRUMENTS 82, 086113 (2011) Note: Piezoelectric strain voltage sensing at ultra-low frequencies

    E-print Network

    Moheimani, Reza

    2011-01-01

    transducer. These charges result in an electric field that may be measured as a voltage difference between through a high impedance buffer.9 How- ever, there is often a limit below which accurate sensing

  7. A soft-switched, high-frequency resonant rectifier and characteristics of the controlled system

    Microsoft Academic Search

    Hyun Chil Choi; Myung Joong Youn

    1997-01-01

    In this paper, a high frequency and soft-switched AC\\/DC rectifier employing a series-type resonant circuit is proposed to obtain the sinusoidal AC line current. Using the proposed rectifier, the high power factor and low harmonic currents are obtained in the AC line. Furthermore, several advantages such as the high power density and wide output voltage range can also be available.

  8. Voltage Divider

    NSDL National Science Digital Library

    This voltage divider produces an output voltage, Vo, that is proportional to the input voltage, Vs. The output voltage is measured using a voltmeter. The input voltage is the voltage of the voltage source. The constant of proportionality is called the gain of the voltage divider. The value of the gain of the voltage divider is determined by the resistances, R1 and R2, of the two resistors that comprise the voltage divider.

  9. Optical voltage reference

    DOEpatents

    Rankin, R.; Kotter, D.

    1994-04-26

    An optical voltage reference for providing an alternative to a battery source is described. The optical reference apparatus provides a temperature stable, high precision, isolated voltage reference through the use of optical isolation techniques to eliminate current and impedance coupling errors. Pulse rate frequency modulation is employed to eliminate errors in the optical transmission link while phase-lock feedback is employed to stabilize the frequency to voltage transfer function. 2 figures.

  10. Optical voltage reference

    DOEpatents

    Rankin, Richard (Ammon, ID); Kotter, Dale (Bingham County, ID)

    1994-01-01

    An optical voltage reference for providing an alternative to a battery source. The optical reference apparatus provides a temperature stable, high precision, isolated voltage reference through the use of optical isolation techniques to eliminate current and impedance coupling errors. Pulse rate frequency modulation is employed to eliminate errors in the optical transmission link while phase-lock feedback is employed to stabilize the frequency to voltage transfer function.

  11. Origin and Control of Sinusoidal Nonlinearities in Wavelength-Tuned Littman External Cavity Laser Diodes

    Microsoft Academic Search

    Luc Perret; Pierre Pfeiffer; Nicolas Javahiraly

    2009-01-01

    In a recent paper, we presented the influence of sinusoidal nonlinearities in the wavelength sweeping speed on the performance of an absolute distance interferometry setup. Nonlinearities in an optical frequency modulation system are generally the source of degradation in performance. The interest of this study comes from the experimental observation of the good behavior of an absolute distance measurement system

  12. Corrections for sinusoidal background and non-orthogonality of signal channels in sinusoidal rapid magnetic field scans

    PubMed Central

    Tseitlin, Mark; Mitchell, Deborah G.; Eaton, Sandra S.; Eaton, Gareth R.

    2012-01-01

    The rapidly-changing magnetic field of sinusoidal rapid scans creates background signals that are dominated by oscillations at the scan frequency. The background oscillations can be removed without acquiring off-resonance data. For data acquired in quadrature, up-field and down-field scan signals can be separated in the frequency domain. For each scan direction, the background oscillation can be calculated by fitting to the half cycle that does not contain the EPR signal. The extrapolated fit function is then subtracted from the half cycle that contains the EPR signal. By zeroing the array for the half cycles that do not contain the EPR signal, the signal-to-noise is improved and the data are corrected for non-orthogonality of the quadrature channels. PMID:22967891

  13. On-chip frequency compensation with a dual signal path operational transconductance amplifier for a voltage mode control DC/DC converter

    NASA Astrophysics Data System (ADS)

    Qiang, Ye; Jie, Liu; Bing, Yuan; Xinquan, Lai; Ning, Liu

    2012-04-01

    A novel on-chip frequency compensation circuit for a voltage-mode control DC/DC converter is presented. By employing an RC network in the two signal paths of an operational transconductance amplifier (OTA), the proposed circuit generates two zeros to realize high closed-loop stability. Meanwhile, full on-chip integration is also achieved due to its simple structure. Hence, the number of off-chip components and the board space is greatly reduced. The structure of the dual signal path OTA is also optimized to help get a better transition response. Implemented in a 0.5 ?m CMOS process, the voltage mode control DC/DC converter with the proposed frequency compensation circuit exhibits good stability. The test results show that both load and line regulations are less than 0.3%, and the output voltage can be recovered within 15 ?s for a 400 mA load step. Moreover, the compensation components area is less than 2% of the die's area and the board space is also reduced by 11%. The efficiency of the whole chip can be up to 95%.

  14. Trap behaviors in AlGaN/GaN based polarization-doped field effect transistors by frequency-dependent conductance-voltage characterizations

    NASA Astrophysics Data System (ADS)

    Fang, Yulong; Feng, Zhihong; Li, Chengming; Yin, Jiayun; Zhang, Zhirong; Dun, Shaobo; Lv, Yuanjie; Guo, Jianchao; Cai, Shujun

    2015-06-01

    AlGaN/GaN polarization-doped field-effect transistors (PolFETs) were fabricated on the graded AlGaN/GaN heterojunctions grown by metal organic chemical vapor deposition, and the trap behaviors were first systemically evaluated by frequency-dependent conductance-voltage characterizations. It was found that there was no obvious effective traps accumulation in the graded AlGaN/GaN heterojunctions of the PolFETs due to the absence of abrupt heterostructure as in the traditional HFETs. The exactly exponential dependence of the trap state time constants on the bias voltage in PolFETs was observed, which was a typical characteristic for interface traps, indicating a multi-heterointerface feature of the PolFETs.

  15. A Novel Technique To Estimate the Voltage-Dependent Capacitance of a Weakly Nonlinear Device At Microwave Frequencies

    E-print Network

    Haddadi, Hamed

    through the output transmission line T2 . Measurement of the device nonlinearity involves two steps: a by a single tone signal Vs through the source impedance Rs and the input transmission lineT1 . BecauseA Novel Technique To Estimate the Voltage-Dependent Capacitance of a Weakly Nonlinear Device

  16. Analysis and design of a multiple feedback loop control strategy for single-phase voltage-source UPS inverters

    SciTech Connect

    Abdel-Rahim, N.M.; Quaicoe, J.E. [Memorial Univ. of Newfoundland, St. Johns, Newfoundland (Canada). Faculty of Engineering and Applied Science] [Memorial Univ. of Newfoundland, St. Johns, Newfoundland (Canada). Faculty of Engineering and Applied Science

    1996-07-01

    This paper presents the analysis and design of a multiple feedback loop control scheme for single-phase voltage-source uninterruptible power supply (UPS) inverters with an L-C filter. The control scheme is based on sensing the current in the capacitor of the load filter and using it in an inner feedback loop. An outer voltage feedback loop is also incorporated to ensure that the load voltage is sinusoidal and well regulated. A general state-space averaged model of the UPS system is first derived and used to establish the steady-steady quiescent point. A linearized small signal dynamic model is then developed from the system general model using perturbation and small-signal approximation. The linearized system model is employed to examine the incremental dynamics of the power circuit and select appropriate feedback variables for stable operation of the closed-loop UPS system. Experimental verification of a laboratory model of the UPS system under the proposed closed-loop operation is provided for both linear and nonlinear loads. It is shown that the control scheme offers improved performance measures over existing schemes. It is simple to implement and capable of producing nearly perfect sinusoidal load voltage waveform at moderate switching frequency and reasonable size of filter parameters. Furthermore, the scheme has excellent dynamic response and high voltage utilization of the dc source.

  17. A New Speed-Varying Ellipse Voltage Injection Method for Sensorless Drive of Permanent-Magnet Synchronous Motors With Pole Saliency—New PLL Method Using High-Frequency Current Component Multiplied Signal

    Microsoft Academic Search

    Shinji Shinnaka

    2008-01-01

    This paper proposes a new sensorless vector control method for salient-pole permanent-magnet synchronous motors. With regard to phase estimation, the sensorless vector control method is featured by a new high-frequency voltage injection method (i.e., carrier modulation method), which is distinguished from the conventional ones by a unique ellipse shape of spatially rotating high-frequency voltage, and by a new phase-locked-loop method

  18. Effect of radio-frequency bias voltage on the optical and structural properties of hydrogenated amorphous silicon carbide

    NASA Astrophysics Data System (ADS)

    Cui, J.; Rusli, Yoon, S. F.; Teo, E. J.; Yu, M. B.; Chew, K.; Ahn, J.; Zhang, Q.; Osipowicz, T.; Watt, F.

    2001-06-01

    Hydrogenated amorphous silicon carbide (a-Si1-xCx:H) films have been deposited using the electron cyclotron resonance chemical vapor deposition process under varying negative rf-bias voltage at the substrate. The optical and structural properties of these films are characterized using Rutherford backscattering spectroscopy, transmittance/reflectance spectrophotometry, photothermal deflection spectroscopy, Fourier transform infrared absorption, Raman scattering, and room temperature photoluminescence (PL). These films deposited using a gas mixture of silane, methane, and hydrogen at a constant gas flow ratio showed a slight increase in the carbon fraction x, but very obvious structural transformation, at increasing rf induced bias voltage from -20 to -120 V. Near stoichiometric a-Si1-xCx:H films with a carbon fraction x of almost 0.5 are achieved at low bias voltage range from -20 to -60 V. Visible PL with relatively low efficiency can be observed from such films at room temperature. For larger bias voltages from -80 to -120 V, slightly C-rich a-Si1-xCx:H films (x>0.5) with larger optical gaps are obtained. These films have relatively higher PL efficiency, and the relative quantum efficiency was also found to depend strongly on the optical gap. Structurally, it was found that there is an increase in the hydrogen content and carbon sp2 bonding in the films at larger bias voltages. The latter leads to an increase in the disorder in the films. The linear relationship observed between the Urbach energy E0 and B factor in the Tauc equation suggests that the local defects related to microstructural disorder resulting from alloying with carbon dominate the overall defect structure of the films. Substrate biasing is noted to be crucial for the formation of Si-C bonds, as deduced from the Raman scattering results.

  19. An Improvement Method of Matrix Converter Drives Under Input Voltage Disturbances

    Microsoft Academic Search

    Ikuya Sato; Jun-ichi Itoh; Hideki Ohguchi; Akihiro Odaka; Hironori Mine

    2007-01-01

    While the matrix converter has many advantages that include bidirectional power flow, a size reduction, a long lifetime, and sinusoidal input currents, it is vulnerable to the input voltage disturbances, because it directly exchanges the input voltage to the output voltage. The instantaneous effective power control (IEPC) method has been proposed to compensate the input voltage disturbances, in which the

  20. OPEN-SOURCE MATLAB TOOLS FOR INTERPOLATION OF SDIF SINUSOIDAL SYNTHESIS PARAMETERS

    Microsoft Academic Search

    Matthew Wright; Julius O. Smith

    We have implemented an open-source additive synthesizer in the matlab language that reads sinusoidal models from SDIF files and synthesizes them with a variety of methods for interpolating frequency, amplitude, and phase between frames. Interpolation techniques currently implemented include linear frequency and amplitude ignoring all but initial phase, dB scale amplitude interpolation, stair-step, and cubic polynomial phase interpolation. A plug-in

  1. High-Efficient High Frequency Linked Zero Voltage Soft Switching PWM DC/DC Power Converter with ON/OFF-Assisted Synchronous Rectifier Scheme

    NASA Astrophysics Data System (ADS)

    Sato, Shinji; Moisseev, Serguei; Ishitobi, Manabu; Hiraki, Eiji; Nakaoka, Mutsuo

    Advanced development of the high frequency pulse modulated DC/DC power converters are indispensable in order to achieve smaller size, higher performances of the power supplies. In resent years the problems of the electromagnetic noise generation caused by the hard-switching pulse width modulation (PWM)—based high frequency operation of the switching power devices have been significant, including switching losses and switching surges. As result a variety of soft-switching power conversion circuit technologies have been attracted special interests for reducing switching power losses and minimizing electromagnetic interference. The soft-switching pulse modulation of DC/DC power circuit topologies can be divided into continuous current mode resonant type and quasi-resonant voltage mode type. The soft-switching DC/DC converters, a continuous current mode zero current soft-switching (ZCS) DC/DC converter with pulse frequency modulation (PFM) has been already put into a practical use. In this sort of power converters soft-switching commutation can be achieved over wide load variation ranges and high stability can be also performed, but high current peak stress through power semiconductor devices arises, however, and it causes relatively large increase of conduction power losses in the power semiconductor devices, high frequency transformers as well as rectifier diodes. As a result, the problem of a high efficiency for DC/DC power converter could not still unsolved. Thereupon, in this paper, quasi-resonant voltage mode based soft-switching PWM DC/DC power converter with a high frequency transformer link is presented, which has on/off assisted synchronous rectifier in its secondary side. The PWM operation of this converter is described in comparison with conventional one. Due to using power MOSFET as on/off assisted synchronous rectifier in the secondary side of the high frequency isolated transformer, it is possible to achieve stable zero voltage soft-switching (ZVS) conditions from no load to the rated load for minimum requirement of a magnetizing current. As result of a high value of the magnetizing inductance design, the power converter actual efficiency of this converter can be designed so as to above 97% in experiment. Moreover, results of a switching losses analysis are discussed from an experimental point of views in this paper. The effectiveness of the power converter treated hare is proved from a practical point of view by using 32kHz-2.5kW breadboard setup.

  2. Potential damage to DC superconducting magnets due to the high frequency electromagnetic waves

    NASA Technical Reports Server (NTRS)

    Gabriel, G. J.

    1977-01-01

    Experimental data are presented in support of the hypothesis that a dc superconducting magnet coil does not behave strictly as an inductor, but as a complicated electrodynamic device capable of supporting electromagnetic waves. Travel times of nanosecond pulses and evidence of sinusoidal standing waves were observed on a prototype four-layer solenoidal coil at room temperature. Ringing observed during switching transients appears as a sequence of multiple reflected square pulses whose durations are related to the layer lengths. With sinusoidal excitation of the coil, the voltage amplitude between a pair of points on the coil exhibits maxima at those frequencies such that the distance between these points is an odd multiple of half wavelength in free space. Evidence indicates that any disturbance, such as that resulting from switching or sudden fault, initiates multiple reflections between layers, thus raising the possibility for sufficiently high voltages to cause breakdown.

  3. PhET Teacher Ideas & Activities: Applications of Sinusoidal Functions

    NSDL National Science Digital Library

    Andrzej Sokolowski

    This activity is intended to supplement the "Wave on a String" PhET simulation. Students apply the concepts introduced in the computer simulation to explore properties of sinusoidal functions. They will find an equation of a wave with pre-set components and analyze how amplitude, frequency, and tension influence changes in the wave motion. The activity is intended to take ~60 minutes to complete. The wave simulation, which must be open and displayed to complete this activity, is available from PhET at: Wave on a String. This lesson is part of PhET (Physics Education Technology Project), a large collection of free interactive simulations for science education.

  4. Field oriented control of an induction machine in a high frequency link power system

    NASA Technical Reports Server (NTRS)

    Sul, Seung K.; Lipo, Thomas A.

    1988-01-01

    A field-oriented controlled induction machine drive operating with a high-frequency single-phase sinusoidal voltage link is presented. System performance is investigated by computer simulation and is verified by a test on a prototype system. A novel control loop to minimize the link voltage fluctuation is proposed. The capability of rapid demagnetization of the induction machine by current regulation is investigated. A current-modulation technique termed mode control is proposed, and its performance is compared with that of the conventional delta-modulation technique.

  5. Combined effect of constant high voltage electrostatic field and variable frequency pulsed electromagnetic field on the morphology of calcium carbonate scale in circulating cooling water systems.

    PubMed

    Zhao, Ju-Dong; Liu, Zhi-An; Zhao, Er-Jun

    2014-01-01

    Research on scale inhibition is of importance to improve the heat transfer efficiency of heat exchangers. The combined effect of high voltage electrostatic and variable frequency pulsed electromagnetic fields on calcium carbonate precipitation was investigated, both theoretically and experimentally. Using energy dispersive spectrum analysis, the predominant phase was found to be CaCO(3). The formed crystal phases mainly consist of calcite and aragonite, which is, in part, verified by theory. The results indicate that the setting of water flow velocity, and high voltage electrostatic and variable frequency pulsed electromagnetic fields is very important. Favorable values of these parameters can have a significant anti-scaling effect, with 68.95% of anti-scaling ratio for scale sample 13, while unfavorable values do not affect scale inhibition, but rather promoted fouling, such as scale sample 6. By using scanning electron microscopy analysis, when the anti-scaling ratio is positive, the particle size of scale was found to become smaller than that of untreated sample and the morphology became loose. The X-ray diffraction results verify that the good combined effect favors the appearance and growth of aragonite and restrains its transition to calcite. The mechanism for scale reduction is discussed. PMID:25259497

  6. Observation of peripheral charge induced low frequency capacitance-voltage behaviour in metal-oxide-semiconductor capacitors on Si and GaAs substrates

    NASA Astrophysics Data System (ADS)

    O'Connor, É.; Cherkaoui, K.; Monaghan, S.; O'Connell, D.; Povey, I.; Casey, P.; Newcomb, S. B.; Gomeniuk, Y. Y.; Provenzano, G.; Crupi, F.; Hughes, G.; Hurley, P. K.

    2012-06-01

    We report on experimental observations of room temperature low frequency capacitance-voltage (CV) behaviour in metal oxide semiconductor (MOS) capacitors incorporating high dielectric constant (high-k) gate oxides, measured at ac signal frequencies (2 kHz to 1 MHz), where a low frequency response is not typically expected for Si or GaAs MOS devices. An analysis of the inversion regions of the CV characteristics as a function of area and ac signal frequency for both n and p doped Si and GaAs substrates indicates that the source of the low frequency CV response is an inversion of the semiconductor/high-k interface in the peripheral regions outside the area defined by the metal gate electrode, which is caused by charge in the high-k oxide and/or residual charge on the high-k oxide surface. This effect is reported for MOS capacitors incorporating either MgO or GdSiOx as the high-k layers on Si and also for Al2O3 layers on GaAs(111B). In the case of NiSi/MgO/Si structures, a low frequency CV response is observed on the p-type devices, but is absent in the n-type devices, consistent with positive charge (>8 × 1010 cm-2) on the MgO oxide surface. In the case of the TiN/GdSiOx/Si structures, the peripheral inversion effect is observed for n-type devices, in this case confirmed by the absence of such effects on the p-type devices. Finally, for the case of Au/Ni/Al2O3/GaAs(111B) structures, a low-frequency CV response is observed for n-type devices only, indicating that negative charge (>3 × 1012 cm-2) on the surface or in the bulk of the oxide is responsible for the peripheral inversion effect.

  7. Energy harvesting under excitations of time-varying frequency

    NASA Astrophysics Data System (ADS)

    Seuaciuc-Osório, Thiago; Daqaq, Mohammed F.

    2010-06-01

    The design and optimization of energy harvesters capable of scavenging energy efficiently from realistic environments require a deep understanding of their transduction under non-stationary and random excitations. Otherwise, their small energy outputs can be further decreased lowering their efficiency and rendering many critical and possibly life saving technologies inefficient. As a first step towards this critical understanding, this effort investigates the response of energy harvesters to harmonic excitations of time-varying frequency. Such excitations can be used to represent the behavior of realistic vibratory environments whose frequency varies or drifts with time. Specifically, we consider a piezoelectric stack-type harvester subjected to a harmonic excitation of constant amplitude and a sinusoidally varying frequency. We analyze the response of the harvester in the fixed-frequency scenario then use the Jacobi-Anger's expansion to analyze the response in the time-varying case. We obtain analytical expressions for the harvester's response, output voltage, and power. In-depth analysis of the attained results reveals that the solution to the more complex time-varying frequency can be understood through a process which "samples" the fixed-frequency response curve at a discrete and fixed frequency interval then multiplies the response by proper weights. Extensive discussions addressing the effect of the excitation parameters on the output power is presented leading to some initial suggestions pertinent to the harvester's design and optimization in the sinusoidally varying frequency case.

  8. Spur-reduced digital sinusoid synthesis

    NASA Technical Reports Server (NTRS)

    Flanagan, M. J.; Zimmerman, G. A.

    1993-01-01

    This article presents and analyzes a technique for reducing the spurious signal content in digital sinusoid synthesis. Spurious-harmonic (spur) reduction is accomplished through dithering both amplitude and phase values prior to word-length reduction. The analytical approach developed for analog quantization is used to produce new bounds on spur performance in these dithered systems. Amplitude dithering allows output word-length reduction without introducing additional spurs. Effects of periodic dither similar to those produced by a pseudonoise (PN) generator are analyzed. This phase-dithering method provides a spur reduction of 6(M plus one) dB per phase bit when the dither consists of M uniform variates. While the spur reduction is at the expense of an increase in system noise, the noise power can be made white, making the power spectral density small. This technique permits the use of a smaller number of phase bits addressing sinusoid lookup tables, resulting in an exponential decrease in system complexity. Amplitude dithering allows the use of less complicated multipliers and narrower data paths in purely digital applications, as well as the use of coarse resolution, highly linear digital to analog converters (DAC's) to obtain spur performance limited by the DAC linearity rather than its resolution.

  9. Optical frequency comb generation based on chirping of Mach-Zehnder Modulators

    NASA Astrophysics Data System (ADS)

    Hmood, Jassim K.; Emami, Siamak D.; Noordin, Kamarul A.; Ahmad, Harith; Harun, Sulaiman W.; Shalaby, Hossam M. H.

    2015-06-01

    A new approach for the generation of an optical frequency comb, based on chirping of modulators, is proposed and numerically demonstrated. The setup includes two cascaded Mach-Zehnder Modulators (MZMs), a sinusoidal wave oscillator, and an electrical time delay. The first MZM is driven directly by a sinusoidal wave, while the second MZM is driven by a delayed replica of the sinusoidal wave. A mathematical model of the proposed system is formulated and modeled using the Matlab software. It is shown that the number of the frequency lines is directly proportional to the chirp factor. In order to achieve the highest number of frequency comb lines with the best flatness, the time delay between the driving voltages of the two MZMs is optimized. Our results reveal that at least 51 frequency lines can be observed at the output spectrum. In addition, 27 of these lines have power fluctuations of less than 1 dB. The performance of the proposed system is also simulated using a split-step numerical analysis. An optical frequency comb, with tunable frequency spacing ranging from 5 to 40 GHz, is successfully generated.

  10. Response of the normal human ankle joint to imposed sinusoidal movements.

    PubMed

    Evans, C M; Fellows, S J; Rack, P M; Ross, H F; Walters, D K

    1983-11-01

    Ankle joints were subjected to sinusoidal movements at a range of amplitudes and frequencies. Records were made of electromyograms (e.m.g.s) in calf muscles, and of the forces at the joints. When the leg is relaxed, the ankle joint resists an imposed sinusoidal movement with a small approximately sinusoidal force. It is stiffer in its resistance to small movements than to large ones, and this resistance is greater when the joint is dorsiflexed than when it is plantarflexed. If the subject exerts a steady mean flexing force, the imposed sinusoidal movement generates reflex activity which may be recorded as a modulation of the gastrocnemius and soleus e.m.g.s. The e.m.g. response to the sinusoidal movement occurs later in cycles of movement at high than at low frequencies, as one could expect of a reflex pathway that involves a delay. The results suggest that this delay is between 50 and 60 ms, and we conclude that under these circumstances spinal stretch reflexes are playing the important part. The relation of the resisting force to the movement has been displayed as a vector. As the frequency changes, this vector describes the circular path that is characteristic of a system which includes delays or lags; this path enables one to draw conclusions about the amplitude and timing of the reflex resistance to the movement. When a subject exerts a moderate flexing force against the sinusoidal movement for some minutes, the reflex response becomes progressively potentiated. A subject whose reflex responses are normally slight may then exhibit a vigorous reflex response to the movement of that ankle. This enhancement of spinal reflex activity was accompanied by an increase in the myotatic reflex response at the ankle. Reflex responses to sinusoidal movement were most clearly seen when the subject exerted a mean flexing force that amounted to about one-fifth of his maximum. Very small movements (+/- 0.5 degrees) generated little or no reflex response. With large amplitudes of movement there was more reflex activity, but at some amplitude (which varied from subject to subject and from time to time) the reflex mechanism appeared to 'saturate', and further increases in amplitude were not accompanied by comparable increases in the reflex response. With movements at 10-15 Hz the e.m.g. response often became large in alternate cycles, with less activity in the intervening cycles.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:6655591

  11. Experimental and analytical study of sinusoidal buckling in vertical wells

    SciTech Connect

    Salies, J.B.; Cunha, J.C.S. [Petrobras, Rio de Janeiro (Brazil); [Univ. of Tulsa, OK (United States); Azar, J.J.; Soren, J.R. Jr. [Univ. of Tulsa, OK (United States)

    1994-12-31

    This paper presents results from experimental data for sinusoidal buckling of tubulars in vertical wells and discusses some analytical solutions presented in the literature. An experimental apparatus 55 feet long was used in the tests. Several tests have been conducted and the results are presented and analyzed. The following aspects of sinusoidal buckling were observed during the tests: critical sinusoidal buckling force, contact point between pipe and wellbore, further buckling modes, effect of friction in the post buckling behavior.

  12. High frequency, high temperature specific core loss and dynamic B-H hysteresis loop characteristics of soft magnetic alloys

    NASA Technical Reports Server (NTRS)

    Wieserman, W. R.; Schwarze, G. E.; Niedra, J. M.

    1990-01-01

    Limited experimental data exists for the specific core loss and dynamic B-H loop for soft magnetic materials for the combined conditions of high frequency and high temperature. This experimental study investigates the specific core loss and dynamic B-H loop characteristics of Supermalloy and Metglas 2605SC over the frequency range of 1 to 50 kHz and temperature range of 23 to 300 C under sinusoidal voltage excitation. The experimental setup used to conduct the investigation is described. The effects of the maximum magnetic flux density, frequency, and temperature on the specific core loss and on the size and shape of the B-H loops are examined.

  13. High frequency, high temperature specific core loss and dynamic B-H hysteresis loop characteristics of soft magnetic alloys

    NASA Technical Reports Server (NTRS)

    Wieserman, W. R.; Schwarze, G. E.; Niedra, J. M.

    1990-01-01

    Limited experimental data exists for the specific core loss and dynamic B-H loops for soft magnetic materials for the combined conditions of high frequency and high temperature. This experimental study investigates the specific core loss and dynamic B-H loop characteristics of Supermalloy and Metglas 2605SC over the frequency range of 1 to 50 kHz and temperature range of 23 to 300 C under sinusoidal voltage excitation. The experimental setup used to conduct the investigation is described. The effects of the maximum magnetic flux density, frequency, and temperature on the specific core loss and on the size and shape of the B-H loops are examined.

  14. High frequency, high temperature specific core loss and dynamic B-H hysteresis loop characteristics of soft magnetic alloys

    SciTech Connect

    Wieserman, W.R. [Univ. of Pittsburgh, Johnstown, PA (United States); Schwarze, G.E. [National Aeronautics and Space Administration, Cleveland, OH (United States). Lewis Research Center; Niedra, J.M. [Sverdrup Technology, Inc., Brook Park, OH (United States). Lewis Research Center Group

    1994-09-01

    Limited experimental data exists for the specific core loss and dynamic B-H loops for soft magnetic materials for the combined conditions of high frequency and high temperature. This experimental study investigates the specific core loss and dynamic B-H loop characteristics of Supermalloy and Metglass 2605SC over the frequency range of 1-50 kHz and temperature range of 23-300 C under sinusoidal voltage excitation. The experimental setup used to conduct the investigation is described. The effects of the maximum magnetic flux density, frequency, and temperature on the specific core loss and on the size and shape of the B-H loops are examined.

  15. High frequency, high temperature specific core loss and dynamic B-H hysteresis loop characteristics of soft magnetic alloys

    NASA Astrophysics Data System (ADS)

    Wieserman, W. R.; Schwarze, G. E.; Niedra, J. M.

    Limited experimental data exists for the specific core loss and dynamic B-H loop for soft magnetic materials for the combined conditions of high frequency and high temperature. This experimental study investigates the specific core loss and dynamic B-H loop characteristics of Supermalloy and Metglas 2605SC over the frequency range of 1 to 50 kHz and temperature range of 23 to 300 C under sinusoidal voltage excitation. The experimental setup used to conduct the investigation is described. The effects of the maximum magnetic flux density, frequency, and temperature on the specific core loss and on the size and shape of the B-H loops are examined.

  16. Design and Digital Implementation of Constant Frequency Hysteresis Current Controller for Three-Phase Voltage Source Inverter Using TMS320F2812

    NASA Astrophysics Data System (ADS)

    Kalyanraj, D.; Lenin Prakash, S.

    2014-01-01

    A constant frequency hysteresis current control technique for a three-phase voltage source inverter (VSI) has been developed for AC drives, power quality and renewable energy applications. This paper presents a digital implementation of a constant frequency hysteresis current control technique for a three-phase VSI feeding an inductive load, using digital signal controller TMS320F2812. The limitations of variable frequency hysteresis control have been discussed and overcoming these limitations by means of digital implementation has been proposed. The complete design procedure of the proposed technique has been presented with an illustrative example. The three-phase VSI feeding an inductive load has also been simulated by using MATLAB and the simulation results have been presented. The hardware results of hysteresis current controlled three-phase VSI feeding an inductive load have been presented. Also the performance analysis of the hysteresis current controller has been presented. Operation of this controller has also been explained with a help of phase plane trajectory of hysteresis controller.

  17. Attenuation of Sinusoidal Perturbations Superimposed on Laminar Flow of a Liquid in a Long Line

    NASA Technical Reports Server (NTRS)

    Holland, Carl M.; Blade, Robert J.; Dorsch, Robert G.

    1965-01-01

    The attenuation constant for sinusoidal pressure and flow perturbations superimposed on the laminar flow of a viscous liquid was measured in a system consisting of a long, straight, cylindrical hydraulic line. The upstream and downstream ends of the line were securely fastened t o the ground. A sinusoidal perturbation was imposed on the mean flow at the upstream end by means of a s m a l l oscillation of a throttle valve abmt a partly open mean position. The downstream end was terminated in a restricting orifice. Pressure perturbations were measured at three locations along the line for frequencies from 15 t o 100 cps. These pressure measurements were reduced by use of a pair of complex damped acoustic one-dimensional wave equations to obtain the attenuation constant along with the phase constant and the dimensionless downstream admittance. For the range of frequencies investigated, the experimental values of the attenuation constant are in good agreement with classical theory.

  18. Nonequilibrium atmospheric pressure plasma jet using a combination of 50 kHz/2 MHz dual-frequency power sources

    SciTech Connect

    Zhou, Yong-Jie; Yuan, Qiang-Hua; Li, Fei; Wang, Xiao-Min; Yin, Gui-Qin; Dong, Chen-Zhong [Key Laboratory of Atomic and Molecular Physics and Functional Materials of Gansu Province, College of Physics and Electronic Engineering, Northwest Normal University, Lanzhou 730070 (China)] [Key Laboratory of Atomic and Molecular Physics and Functional Materials of Gansu Province, College of Physics and Electronic Engineering, Northwest Normal University, Lanzhou 730070 (China)

    2013-11-15

    An atmospheric pressure plasma jet is generated by dual sinusoidal wave (50 kHz and 2 MHz). The dual-frequency plasma jet exhibits the advantages of both low frequency and radio frequency plasmas, namely, the long plasma plume and the high electron density. The radio frequency ignition voltage can be reduced significantly by using dual-frequency excitation compared to the conventional radio frequency without the aid of the low frequency excitation source. A larger operating range of ? mode discharge can be obtained using dual-frequency excitation which is important to obtain homogeneous and low-temperature plasma. A larger controllable range of the gas temperature of atmospheric pressure plasma could also be obtained using dual-frequency excitation.

  19. A simplified method for the iron losses prediction in soft magnetic materials with arbitrary voltage supply

    Microsoft Academic Search

    A. Boglietti; M. Lazzari; M. Pastorelli

    2000-01-01

    The aim of this work is to propose a new approach for the iron losses prediction, in soft magnetic materials with any voltage supply, starting from the knowledge of the iron losses with sinusoidal supply. The model is based on the separation of the loss contributions due to hysteresis, eddy currents and excess losses with sinusoidal supply. Since any contribution

  20. An Accurate, Low-Voltage, CMOS Switching Power Supply With Adaptive On-Time Pulse-Frequency Modulation (PFM) Control

    Microsoft Academic Search

    Biranchinath Sahu; Gabriel A. Rincón-Mora

    2007-01-01

    Integrated switching power supplies with multimode control are gaining popularity in state-of-the-art portable applications like cellular phones, personal digital assistants (PDAs), etc., because of their ability to adapt to various loading conditions and therefore achieve high efficiency over a wide load-current range, which is critical for extended battery life. Constant-frequency, pulsewidth modulated (PWM) switching converters, for instance, have poor light-load

  1. Two discrete oscillator based adaptive notch filters (OSC ANFs) for noisy sinusoids

    Microsoft Academic Search

    Ho-En Liao

    2005-01-01

    We propose two adaptive notch filters (ANFs) for sinusoids embedded in a noisy environment. Both of the ANFs, as usual, are structurally composed of a time-variant infinite-impulse-response (IIR) filter that serves as a line-enhancer and an adaptive mechanism that serves as a frequency estimator. The novelty of ANFs is that the derivations of the coefficient-updating algorithms for the adaptive mechanisms

  2. Wind turbines using self-excited three-phase induction generators: an innovative solution for voltage-frequency control

    NASA Astrophysics Data System (ADS)

    Brudny, J. F.; Pusca, R.; Roisse, H.

    2008-08-01

    A considerable number of communities throughout the world, most of them isolated, need hybrid energy solutions either for rural electrification or for the reduction of diesel use. Despite several research projects and demonstrations which have been conducted in recent years, wind-diesel technology remains complex and much too costly. Induction generators are the most robust and common for wind energy systems but this option is a serious challenge for electrical regulation. When a wind turbine is used in an off-grid configuration, either continuously or intermittently, precise and robust regulation is difficult to attain. The voltage parameter regulation option, as was experienced at several remote sites (on islands and in the arctic for example), is a safe, reliable and relatively simple technology, but does not optimize the wave quality and creates instabilities. These difficulties are due to the fact that no theory is available to describe the system, due to the inverse nature of the problem. In order to address and solve the problem of the unstable operation of this wind turbine generator, an innovative approach is described, based on a different induction generator single phase equivalent circuit.

  3. Current-voltage and low frequency noise measurements on LT-InAlAs grown by MBE

    SciTech Connect

    Meva`a, C.; Rojo-Romeo, P.; Letartre, X.; Viktorovitch, P. [Ecole Centrale de Lyon, Ecully (France)

    1996-12-31

    The properties of InAlAs layers grown lattice matched to InP by molecular beam epitaxy (MBE) were investigated. For a large range of growth conditions (temperature, V/III beam equivalent pressure ratio, doping level), the authors have detected 3 deep electron trap families E1, E2, and E3 in the material bandgap. The presence of these traps give rise to a defect-assisted tunneling current in the space-charge region of Schottky diodes at low forward and reverse biases. The observed low frequency 1/f{gamma} in reverse bias is interpreted in terms of fluctuations of the Schottky barrier height.

  4. Frequency Domain Controller Design 9.2 Frequency Response Characteristics

    E-print Network

    Gajic, Zoran

    Frequency Domain Controller Design 9.2 Frequency Response Characteristics The frequency transfer functions are defined for sinusoidal inputs having all possible frequencies . They are obtained from (9.1) by simply setting , that is (9.1) Typical diagrams for the magnitude and phase of the open-loop frequency

  5. Linear fibroblast alignment on sinusoidal wave micropatterns.

    PubMed

    Gamboa, Jessica R; Mohandes, Samir; Tran, Phat L; Slepian, Marvin J; Yoon, Jeong-Yeol

    2013-04-01

    Micrometer and nanometer grooved surfaces have been determined to influence cellular orientation, morphology, and migration through contact guidance. Cells typically elongate along the direction of an underlying groove and often migrate with guidance provided by constraints of the pattern. This phenomenon has been studied primarily using linear grooves, post, or well patterns. We investigated the behavior of mouse embryonic fibroblasts on non-linear, sinusoidal wave grooves created via electron beam lithography on a polymethyl methacrylate (PMMA) substrate that was spin-coated onto a positively charged glass surface. Three different wave patterns, with varying wavelengths and amplitudes, and two different line patterns were created. Cell orientation and adhesion was examined after 4, 24, and 48 h after cell seeding. Attachment strength was studied via subjecting cells on substrates to centrifugal force following a 24-h incubation period. For all wave patterns studied, it was noted that cells did not reside within the groove, rather they were observed to cross over each groove, residing both inside and outside of each wave pattern, aligning linearly along the long axis of the pattern. For the linear patterns, we observed that cells tended to reside within the grooves, consistent with previous observations. The ability to add texture to a surface to manipulate cell adhesion strength and growth with only localized attachment, maintaining free space in curvilinear microtopography underlying the cell, may be a useful addition for tissue engineering and the fabrication of novel biomedical devices. PMID:23375052

  6. Computer Program for Thin Wire Antenna over a Perfectly Conducting Ground Plane. [using Galerkins method and sinusoidal bases

    NASA Technical Reports Server (NTRS)

    Richmond, J. H.

    1974-01-01

    A computer program is presented for a thin-wire antenna over a perfect ground plane. The analysis is performed in the frequency domain, and the exterior medium is free space. The antenna may have finite conductivity and lumped loads. The output data includes the current distribution, impedance, radiation efficiency, and gain. The program uses sinusoidal bases and Galerkin's method.

  7. Microfluidic System for Generation of Sinusoidal Glucose Waveforms for Entrainment of Islets of Langerhans

    PubMed Central

    Zhang, Xinyu; Grimley, Alix; Bertram, Richard; Roper, Michael G.

    2010-01-01

    A microfluidic system was developed to produce sinusoidal waveforms of glucose to entrain oscillations of intracellular [Ca2+] in islets of Langerhans. The work described is an improvement to a previously reported device where two pneumatic pumps delivered pulses of glucose and buffer to a mixing channel. The mixing channel acted as a low pass filter to attenuate these pulses to produce the desired final concentration. Improvements to the current device included increasing the average pumping frequency from 0.83 Hz to 3.33 Hz by modifying the on-chip valves to minimize adhesion between the PDMS and glass within the valve. The cutoff frequency of the device was increased from 0.026 Hz to 0.061 Hz for sinusoidal fluorescein waves by shortening the length of the mixing channel to 3.3 cm. The value of the cutoff frequency was chosen between the average pumping frequency and the low frequency (?0.0056 Hz) glucose waves that were needed to entrain islets of Langerhans. In this way, the pulses from the pumps were attenuated greatly, but the low frequency glucose waves were not. Using this microfluidic system, a total flow rate of 1.5 ± 0.1 ?L min-1 was generated and used to deliver sinusoidal waves of glucose concentration with a median value of 11 mM and amplitude of 1 mM to a chamber that contained an islet of Langerhans loaded with the Ca2+-sensitive fluorophore, indo-1. Entrainment of the islets was demonstrated by pacing the rhythm of intracellular [Ca2+] oscillations to oscillatory glucose levels produced by the device. The system should be applicable to a wide range of cell types to aid in understanding cellular responses to dynamically changing stimuli. PMID:20617825

  8. System and component design and test of a 10 hp, 18,000 rpm AC dynamometer utilizing a high frequency AC voltage link, part 1

    NASA Technical Reports Server (NTRS)

    Lipo, Thomas A.; Alan, Irfan

    1991-01-01

    Hard and soft switching test results conducted with one of the samples of first generation MOS-controlled thyristor (MCTs) and similar test results with several different samples of second generation MCT's are reported. A simple chopper circuit is used to investigate the basic switching characteristics of MCT under hard switching and various types of resonant circuits are used to determine soft switching characteristics of MCT under both zero voltage and zero current switching. Next, operation principles of a pulse density modulated converter (PDMC) for three phase (3F) to 3F two-step power conversion via parallel resonant high frequency (HF) AC link are reviewed. The details for the selection of power switches and other power components required for the construction of the power circuit for the second generation 3F to 3F converter system are discussed. The problems encountered in the first generation system are considered. Design and performance of the first generation 3F to 3F power converter system and field oriented induction moter drive based upon a 3 kVA, 20 kHz parallel resonant HF AC link are described. Low harmonic current at the input and output, unity power factor operation of input, and bidirectional flow capability of the system are shown via both computer and experimental results. The work completed on the construction and testing of the second generation converter and field oriented induction motor drive based upon specifications for a 10 hp squirrel cage dynamometer and a 20 kHz parallel resonant HF AC link is discussed. The induction machine is designed to deliver 10 hp or 7.46 kW when operated as an AC-dynamo with power fed back to the source through the converter. Results presented reveal that the proposed power level requires additional energy storage elements to overcome difficulties with a peak link voltage variation problem that limits reaching to the desired power level. The power level test of the second generation converter after the addition of extra energy storage elements to the HF link are described. The importance of the source voltage level to achieve a better current regulation for the source side PDMC is also briefly discussed. The power levels achieved in the motoring mode of operation show that the proposed power levels achieved in the generating mode of operation can also be easily achieved provided that no mechanical speed limitation were present to drive the induction machine at the proposed power level.

  9. A Novel Voltage Transients Base Protection Criterion for T-Type High Voltage Transmission Lines

    Microsoft Academic Search

    Xia Mingchao; Lin Yong

    2007-01-01

    Based on the wavelet transform results of the voltage transients from the three ends of the line, a novel protection criterion for T-type high voltage power transmission line is presented. The attenuation effects of high voltage transmission line and busbar capacitance to high-frequency current signals is analyzed. The Transient Voltage Content Ratio (TVCR) and Transient Voltage Singularity Ratio (TVSR) are

  10. Contrasting characteristics of pulsed and sinusoidal cold atmospheric plasma jets

    SciTech Connect

    Walsh, J.L.; Shi, J.J.; Kong, M.G. [Department of Electronic and Electrical Engineering, Loughborough University, Loughborough, Leicestershire LE11 3TU (United Kingdom)

    2006-04-24

    Pulsed excitation of cold atmospheric plasmas is commonly believed to offer valuable benefits compared to the mainstream sinusoidal excitation. However, direct comparison of pulsed and sinusoidal atmospheric plasmas remains few, if any, thus casting an uncertainty of whether pulsed excitation facilitates any significant advantage. In this letter, we report a comparison study of pulsed and sinusoidal cold atmospheric plasma jets through electrical characterization, gas temperature measurement, and optical detection of reactive plasma species. An example of pulsed excitation is shown to reduce the electrical energy consumption by a factor of 12 for producing the same amount of oxygen atoms.

  11. The postural response of normal dogs to sinusoidal displacement

    PubMed Central

    Brookhart, John M.; Talbott, Richard E.

    1974-01-01

    1. Normal dogs were trained to adopt a laterally symmetric stance on a horizontal platform. Sinusoidal oscillation of the platform in the cephalocaudal direction caused the dogs to adopt a strategy of response which would keep them from falling down during the period of imposed motion or perturbation. 2. A Fourier analysis of the response variables provided a quantitative measure of the distortion in the induced movement at the various hind leg joints and in the motion of the body. Certain aspects of the distortion could be accounted for by recognized random events such as drift and panting. The remainder of the distortion was task related and therefore provided evidence that the dog's postural control system behaved essentially as a non-linear system. 3. The motion of the body was less distorted than the motion at the joints. The frequency response of the body motion resembled that of a second order linear system, but the amplitude of the body motion did not vary in constant proportion with changes in the amplitude of the input. Further, the phase relation between body motion and platform motion was not constant when the amplitude of the input was changed. Therefore, it was concluded that the control of the body position was probably non-linearly related to the input disturbance but that the low pass filter characteristics tended to minimize the appearance of distortion in that system output. 4. Control of the position of the hind limb is related to the control of the torque generated at the hind limb joints. To the extent that joint angle and change in joint angle are related to the torque at a joint, the distortion of the motion at the joints clearly demonstrates that control of the hind limb during this postural task was non-linearly related to the sinusoidal input. 5. The uniformity of the response parameters, as assessed from the Fourier coefficients, indicated that all of the tested dogs adopted the same or nearly the same strategy for solving the problem of adjusting their postural control in response to the perturbation. Therefore, a reasonable hypothesis for future testing is that the central programme which generates this particular postural response will be structured similarly from one dog to the next. PMID:4449066

  12. Signal Analysis Algorithms for Optimized Fitting of Nonresonant Laser Induced Thermal Acoustics Damped Sinusoids

    NASA Technical Reports Server (NTRS)

    Balla, R. Jeffrey; Miller, Corey A.

    2008-01-01

    This study seeks a numerical algorithm which optimizes frequency precision for the damped sinusoids generated by the nonresonant LITA technique. It compares computed frequencies, frequency errors, and fit errors obtained using five primary signal analysis methods. Using variations on different algorithms within each primary method, results from 73 fits are presented. Best results are obtained using an AutoRegressive method. Compared to previous results using Prony s method, single shot waveform frequencies are reduced approx.0.4% and frequency errors are reduced by a factor of approx.20 at 303K to approx. 0.1%. We explore the advantages of high waveform sample rates and potential for measurements in low density gases.

  13. Frequency-Modulation Correlation Spectrometer

    NASA Technical Reports Server (NTRS)

    Margolis, J. S.; Martonchik, J. V.

    1985-01-01

    New type of correlation spectrometer eliminates need to shift between two cells, one empty and one containing reference gas. Electrooptical phase modulator sinusoidally shift frequencies of sample transmission spectrum.

  14. Mutual impedance of nonplanar-skew sinusoidal dipoles

    NASA Technical Reports Server (NTRS)

    Richmond, J. H.; Geary, N. H.

    1974-01-01

    The mutual impedance of nonplanar-skew sinusoidal dipoles is presented as a summation of several exponential integrals with complex arguments. Mathematical models are developed to show the near-zone field of the sinusoidal dipole. The mutual impedance of coupled dipoles is expressed as the sum of four monopole-mobopole impedances to simplify the analysis procedure. The subroutines for solving the parameters of the dipoles are discussed.

  15. Vascular Liver Disease and the Liver Sinusoidal Endothelial Cell

    Microsoft Academic Search

    Laurie D. DeLeve

    \\u000a The hepatic sinusoidal endothelial cell is highly differentiated, with unique morphology and function. It provides a porous\\u000a barrier that facilitates access of the hepatocyte to oxygen and small molecules in the microcirculation. Other specialized\\u000a functions include clearance of colloids and macromolecules, promotion of hepatic stellate cell quiescence, and induction of\\u000a immune tolerance. The hepatic sinusoidal endothelial cell may be injured

  16. Low-frequency noise reduction in vertical MOSFETs having tunable threshold voltage fabricated with 60 nm CMOS technology on 300 mm wafer process

    NASA Astrophysics Data System (ADS)

    Imamoto, Takuya; Ma, Yitao; Muraguchi, Masakazu; Endoh, Tetsuo

    2015-04-01

    In this paper, DC and low-frequency noise (LFN) characteristics have been investigated with actual measurement data in both n- and p-type vertical MOSFETs (V-MOSFETs) for the first time. The V-MOSFETs which was fabricated on 300 mm bulk silicon wafer process have realized excellent DC performance and a significant reduction of flicker (1/f) noise. The measurement results show that the fabricated V-MOSFETs with 60 nm silicon pillar and 100 nm gate length achieve excellent steep sub-threshold swing (69 mV/decade for n-type and 66 mV/decade for p-type), good on-current (281 µA/µm for n-type 149 µA/µm for p-type), low off-leakage current (28.1 pA/µm for n-type and 79.6 pA/µm for p-type), and excellent on–off ratio (1 × 107 for n-type and 2 × 106 for p-type). In addition, it is demonstrated that our fabricated V-MOSFETs can control the threshold voltage (Vth) by changing the channel doping condition, which is the useful and low-cost technique as it has been widely used in the conventional bulk planar MOSFET. This result indicates that V-MOSFETs can control Vth more finely and flexibly by the combined the use of the doping technique with other techniques such as work function engineering of metal-gate. Moreover, it is also shown that V-MOSFETs can suppress 1/f noise (L\\text{gate}WS\\text{Id}/I\\text{d}2 of 10?13–10?11 µm2/Hz for n-type and 10?12–10?10 µm2/Hz for p-type) to one or two order lower level than previously reported nanowire type MOSFET, FinFET, Tri-Gate, and planar MOSFETs. The results have also proved that both DC and 1/f noise performances are independent from the bias voltage which is applied to substrate or well layer. Therefore, it is verified that V-MOSFETs can eliminate the effects from substrate or well layer, which always adversely affects the circuit performances due to this serial connection.

  17. [Analysis of lorentzian line shape function broadened by non-sinusoidal wavelength modulation].

    PubMed

    Sun, You-Qun; Wang, Yun-Tao; Ruan, Chi; Xu, Song-Song

    2014-03-01

    In the present work, the Fourier analysis of Lorentzian line shape broadened by non-sinusoidal wavelength modulation was investigated, in which the third order and above harmonic items were ignored. The analytical expression of n-order Fourier coefficient was brought out, where a variable K named harmonic distortion to characterize the ratio of the second harmonic to the first harmonic was introduced. Numerical simulations based on the cases of K > 0.01 and K < 0.01 were carried out, and the result shows: non-sinusoidal modulation has little effect compared with the sinusoidal modulation when K value is less than 0.01, however, if K value is about 0.1 or higher, the center of the Fourier amplitude curve would deviate from the origin of coordinates. With the increase in the harmonic distortion, the deviation of the curve grows, and high order harmonics are more sensitive to the non-sinusoidal modulation compared with the low order harmonics. In addition, when harmonic distortion cannot be ignored, for example K > 0.01, the effect of different depths of modulation on the odd and even order harmonic amplitude curve is significant. And the numerical simulation shows there exists an optimum value of modulation depth which could minimize the impact of the harmonic distortion, and both large K value and small K value would cause a great error. The conclusion of this work could be applied in error analysis of wavelength modulation spectroscopy system And the results are helpful to deepening understanding of WMS and would be the important reference for some kind of frequency stabilization technology in laser instrument. PMID:25208372

  18. Voltage Drop

    NSDL National Science Digital Library

    The first site with information on voltage drop is provided by Power and System Innovations on their Frequently Asked Questions: Voltage Drop (1) page. Visitors can read what voltage drop is, what causes it, what happens as a result of it, and what the maximum recommended voltage drop is. The second site, Basics of Electricity (2), is part of General Electric's Lighting for Business Web site. Through descriptions and illustrations, the site explains what voltage drop is and gives examples of how it is calculated using Ohm's law. The next site is a lab worksheet that is part of a class from the Electrical and Computer Engineering Department of Montana State University called Voltage Drop in Cables (3). The objective of the lesson is to determine the internal resistance of an extension cord and choose the proper wire size for a particular application. Students are given an explanation of the procedure and a number of questions to answer related to the exercise. The Oregon Building Congress offers the Lesson Plans (4) Web site and the downloadable Voltage Drop educational activity. The lesson, which is suggested to be contained within a unit on formulas and solving literal equations, explores the concept of voltage drop that is encountered in basic wiring. The fifth site entitled Explanation of Voltage Drop in a Series Circuit (5) is offered by the Horizons Electronic Lesson Plan Resource. The page describes voltage drop as an electronic concept, gives a formula determining voltage drop, provides a schematic that helps illustrate the concept, and offers a quiz and answer sheet. Next, from electrician.com, is the online Voltage Drop Calculator (6). Users input the type and size of wire being used, the voltage and phase, circuit length, and amp load to calculate voltage drop and several other parameters. The seventh site, entitled The Hazards of Voltage Drop (7), is provided within the Electrical Construction Maintenance Web site. The page describes how electrical equipment can overheat or even power down if it operates below its voltage rating. It also provides a thorough explanation of how to determine the load's operating voltage. The last site, maintained by Williamson Labs (8), is a comprehensive learning site called Elementary Electricity. Visitors will find a wealth of information here, including fun descriptions, graphics, and animations on all aspects of electricity including voltage drop.

  19. New Direct High Frequency Soft-Switching Inverter-Fed AC-DC Converter with Voltage Doubler for Consumer Magnetron Drive

    Microsoft Academic Search

    H. Sugimura; B. Saha; Hidekazu Muraoka; Sang Pil Mun; T. Mishima; H. Omori; M. Nakaoka

    2007-01-01

    The oscillation voltage (Ebm) is an important parameter of the characteristic constant of a high power microwave generator. When Ebm could be made high, it serves so as to improve the power conversion efficiency of a magnetron. Thus, the newly developed magnetron with 7% higher oscillation cut-off voltage than the present conventional one is manufactured by Matsushita Electric Industrial Co.Ltd.

  20. Low voltage surface transverse wave oscillators for the next generation CMOS technology.

    PubMed

    Avramov, Ivan D

    2005-08-01

    The design and performance of voltage controlled surface transverse wave oscillators (VCSTWO) in the lower gigahertz frequency range, operating on supply and tuning voltages in the 1.2 to 3.3 V range, and suitable for direct interfacing with the next generation CMOS circuits are presented. By applying the "boost" principle, as used in direct current (DC)-DC converters, to the design of the sustaining amplifier, the VCSTWO outputs are switched between 0 V and a positive peak value, exceeding the supply voltage Us, to provide safe CMOS-circuit switching while keeping the radio frequency (RF)/DC efficiency to a maximum for low DC power consumption. The investigated 1.0 and 2.5 GHz VCSTWO are varactor tuned feedback-loop oscillators stabilized with two-port surface transverse wave (STW) resonators. Each VCSTWO has a DC-coupled, high-impedance switched output to drive the CMOS circuit directly, and an additional sinusoidal 50 ohmz high-power reference output available for other low-noise system applications. Phase noise levels in the -103 to -115 dBc/Hz range at 1 kHz carrier offset are achieved with 1.0 GHz VCSTWO at a RF/DC efficiency in the 21 to 29% range. The 2.5 GHz prototypes demonstrate phase noise levels in the -97 to -102 dBc/Hz range at 1 kHz carrier offset, and efficiencies range between 8 and 15%. PMID:16245594

  1. Loss measurements on amorphous alloys under sinusoidal and distorted induction waveform using a digital feedback technique

    NASA Astrophysics Data System (ADS)

    Bertotti, G.; Ferrara, E.; Fiorillo, F.; Pasquale, M.

    1993-05-01

    A newly developed digital feedback wattmeter, allowing power loss measurements in soft laminations under generic induction waveform is presented. The system is intrinsically free of auto-oscillations, typical drawback of analog feedback circuits, and can therefore be operated in a wide frequency range (0.5 Hz-100 kHz). Loss measurements performed by this setup under sinusoidal and distorted induction waveforms on Co based amorphous ribbons are reported. It is shown that the classical approximation to the prediction of power losses under distorted induction largely fails to account for the experimental results. A novel theoretical approach, based on the statistical theory of losses, is discussed and successfully applied to the experiments. In particular, it is shown that knowledge of the loss components under sinusoidal induction at a given magnetizing frequency permits one to make an accurate prediction of the effect of distortion at that frequency as well as other ones. Illustrative applications at 1 kHz and 100 kHz are reported.

  2. Detection of DNA hybridization and extension reactions by an extended-gate field-effect transistor: Characterizations of immobilized DNA–probes and role of applying a superimposed high-frequency voltage onto a reference electrode

    Microsoft Academic Search

    Masao Kamahori; Yu Ishige; Maki Shimoda

    2008-01-01

    As we have already shown in a previous publication [Kamahori, M., Ihige, Y., Shimoda, M., 2007. Anal. Sci. 23, 75–79], an extended-gate field-effect transistor (FET) sensor with a gold electrode, on which both DNA probes and 6-hydroxyl-1-hexanethiol (6-HHT) molecules are immobilized, can detect DNA hybridization and extension reactions by applying a superimposed high-frequency voltage to a reference electrode. However, kinetic

  3. Improvement of a large-amplitude sinusoidal pressure generator for dynamic calibration of pressure transducers

    NASA Technical Reports Server (NTRS)

    Robinson, R. E.

    1972-01-01

    Results of research on the improvement of a sinusoidal pressure generator are presented. The generator is an inlet-area-modulated, gas-flow-through device (siren type) which was developed to dynamically calibrate pressure transducers and pressure probes. Tests were performed over a frequency range of 100 Hz to 20 kHz at average chamber pressures (bias pressure) between 30 and 50 psia (21 and 35 N/sq cm abs) and between 150 and 300 psia (104 and 207 N/sq cm abs). Significant improvements in oscillation pressure waveform were obtained but with reduction in available generator oscillation pressure amplitude range. Oscillation pressure amplitude, waveform, and waveform spectral content are given as functions of frequency for the two bias pressure conditions. The generator and instrumentation for frequency, amplitude, and spectrum measurements are described.

  4. Existence of partial discharges in low-voltage induction machines supplied by PWM drives

    Microsoft Academic Search

    A. Mbaye; F. Grigorescu; T. Lebey; Bui Ai

    1996-01-01

    When standard low voltage induction motors are supplied by pulse-width modulated (PWM) adjustable speed drives, some of the traditional sinusoidal system concepts cannot be applied. This paper reports the results of an investigation of the effect of PWM drives on the insulation of the stator winding. The characteristics of the employed dielectric material and the magnitude of the applied voltages

  5. Medium voltage motor harmonic heating, torques and voltage stress when applied on VFDs

    Microsoft Academic Search

    Frank A. DeWinter; Bin Wu

    1996-01-01

    The increase in the application of medium voltage variable frequency drives to AC motors has raised concerns regarding the effects the drives have on the motors. Most of the published data available is for low voltage motors and drives, which are not necessarily accurate for the medium voltage applications. We address the harmonic heating, torques and voltage stress that are

  6. Half-Tone Video Images Of Drifting Sinusoidal Gratings

    NASA Technical Reports Server (NTRS)

    Mulligan, Jeffrey B.; Stone, Leland S.

    1991-01-01

    Digital technique for generation of slowly moving video image of sinusoidal grating avoids difficulty of transferring full image data from disk storage to image memory at conventional frame rates. Depends partly on trigonometric identity by which moving sinusoidal grating decomposed into two stationary patterns spatially and temporally modulated in quadrature. Makes motion appear smooth, even at speeds much less than one-tenth picture element per frame period. Applicable to digital video system in which image memory consists of at least 2 bits per picture element, and final brightness of picture element determined by contents of "lookup-table" memory programmed anew each frame period and indexed by coordinates of each picture element.

  7. Visual Evoked Cortical Potential (VECP) Elicited by Sinusoidal Gratings Controlled by Pseudo-Random Stimulation

    PubMed Central

    Araújo, Carolina S.; Souza, Givago S.; Gomes, Bruno D.; Silveira, Luiz Carlos L.

    2013-01-01

    The contributions of contrast detection mechanisms to the visual cortical evoked potential (VECP) have been investigated studying the contrast-response and spatial frequency-response functions. Previously, the use of m-sequences for stimulus control has been almost restricted to multifocal electrophysiology stimulation and, in some aspects, it substantially differs from conventional VECPs. Single stimulation with spatial contrast temporally controlled by m-sequences has not been extensively tested or compared to multifocal techniques. Our purpose was to evaluate the influence of spatial frequency and contrast of sinusoidal gratings on the VECP elicited by pseudo-random stimulation. Nine normal subjects were stimulated by achromatic sinusoidal gratings driven by pseudo random binary m-sequence at seven spatial frequencies (0.4–10 cpd) and three stimulus sizes (4°, 8°, and 16° of visual angle). At 8° subtence, six contrast levels were used (3.12–99%). The first order kernel (K1) did not provide a consistent measurable signal across spatial frequencies and contrasts that were tested–signal was very small or absent–while the second order kernel first (K2.1) and second (K2.2) slices exhibited reliable responses for the stimulus range. The main differences between results obtained with the K2.1 and K2.2 were in the contrast gain as measured in the amplitude versus contrast and amplitude versus spatial frequency functions. The results indicated that K2.1 was dominated by M-pathway, but for some stimulus condition some P-pathway contribution could be found, while the second slice reflected the P-pathway contribution. The present work extended previous findings of the visual pathways contribution to VECP elicited by pseudorandom stimulation for a wider range of spatial frequencies. PMID:23940546

  8. Frequency modulation television analysis: Threshold impulse analysis. [with computer program

    NASA Technical Reports Server (NTRS)

    Hodge, W. H.

    1973-01-01

    A computer program is developed to calculate the FM threshold impulse rates as a function of the carrier-to-noise ratio for a specified FM system. The system parameters and a vector of 1024 integers, representing the probability density of the modulating voltage, are required as input parameters. The computer program is utilized to calculate threshold impulse rates for twenty-four sets of measured probability data supplied by NASA and for sinusoidal and Gaussian modulating waveforms. As a result of the analysis several conclusions are drawn: (1) The use of preemphasis in an FM television system improves the threshold by reducing the impulse rate. (2) Sinusoidal modulation produces a total impulse rate which is a practical upper bound for the impulse rates of TV signals providing the same peak deviations. (3) As the moment of the FM spectrum about the center frequency of the predetection filter increases, the impulse rate tends to increase. (4) A spectrum having an expected frequency above (below) the center frequency of the predetection filter produces a higher negative (positive) than positive (negative) impulse rate.

  9. Voltage Controlled Voltage Source (VCVS)

    NSDL National Science Digital Library

    Dorf, Richard C.

    Hosted by Clarkson University, this applet demonstrates a circuit that contains a voltage controlled voltage source (VCVS). The gain may be modified using the scroll bar. Even though brief, this resource can be used in a variety of different technical education classrooms.

  10. Behavior of soft piezoelectric ceramics under high sinusoidal electric fields

    NASA Astrophysics Data System (ADS)

    Kugel, V. D.; Cross, L. E.

    1998-09-01

    The behavior of piezoelectric, dielectric, and elastic characteristics of soft piezoelectric lead zirconate titanate (PZT) ceramics was investigated under sinusoidal electric field E applied along the poling direction and under mechanical stress-free conditions for a frequency range 10 Hz-10 kHz. Electrical displacement D3 along the poling direction, mechanical strain S1 in the direction perpendicular to the poling direction, and the resonant frequency ?r of electromechanically uncoupled bending vibrations of polarized plates were measured. Commercial ceramics PZT5H, 3203HD, and PKI550 with chemical composition near the morphotropic phase boundary were used in the study. It was found that the amplitude and phase of the first harmonic of the relative strain S1(1)/Em and of the relative electrical displacement D3(1)/Em increase similarly with increasing amplitude Em of the electric field if the amplitude is less than coercive field. The corresponding increase in the square of the resonant frequency is more moderate. The dependencies are described well by linear functions except for low electric fields. The functions S1m(1)/Em and D3m(1)/Em demonstrate frequency dispersion as well. Relative amplitude of the second harmonic of the electrical displacement, D3m(2)/D3m(1), which is polar, also increases almost linearly with increasing Em. The relative third harmonic D3m(3)/D3m(1) demonstrates saturationlike behavior. By means of the electric pulse technique, it was found that irreversible changes in the remnant polarization take place even at electric fields much smaller that the coercive field. A mathematical model of a hysteretic transducer, describing the electric field dependence of electromechanical properties of soft piezoelectric PZT ceramics, was suggested. According to this approach, the response depends not only on the instantaneous magnitude of the input signal (e.g., electric field) but also on its past extreme values. It was shown that the experimental Rayleigh law is a particular case of the suggested approach. The model relates directly electric field dependencies of complex piezoelectric coefficient d31(Em) and S1(1)/Em, of complex dielectric permittivity ?33T(Em) and D3(1)/Em, and of the amplitude of elastic compliance s11E(Em) and ?r2. Application of the model to experimental data showed that the model describes well the first three complex harmonics of D3 and the irreversible change in the remnant polarization. Physical causes of the observed behavior were analyzed. As an alternative to the model based on the 90° polarization reorientation and tetragonal/rhombohedral phase boundary motion, a new approach was suggested. In this model, the observed hysteretic changes in the electromechanical properties are assumed to be caused by the electric field dependency of the mechanical stress acting at interdomain boundaries in the partly constrained crystallites of these ceramics.

  11. Vestibular integrator neurons have quadratic functions due to voltage dependent conductances.

    PubMed

    Magnani, Christophe; Eugène, Daniel; Idoux, Erwin; Moore, Lee E

    2013-12-01

    The nonlinear properties of the dendrites of the prepositus hypoglossi nucleus (PHN) neurons are essential for the operation of the vestibular neural integrator that converts a head velocity signal to one that controls eye position. A novel system of frequency probing, namely quadratic sinusoidal analysis (QSA), was used to decode the intrinsic nonlinear behavior of these neurons under voltage clamp conditions. Voltage clamp currents were measured at harmonic and interactive frequencies using specific nonoverlapping stimulation frequencies. Eigenanalysis of the QSA matrix reduces it to a remarkably compact processing unit, composed of just one or two dominant components (eigenvalues). The QSA matrix of rat PHN neurons provides signatures of the voltage dependent conductances for their particular dendritic and somatic distributions. An important part of the nonlinear response is due to the persistent sodium conductance (gNaP), which is likely to be essential for sustained effects needed for a neural integrator. It was found that responses in the range of 10 mV peak to peak could be well described by quadratic nonlinearities suggesting that effects of higher degree nonlinearities would add only marginal improvement. Therefore, the quadratic response is likely to sufficiently capture most of the nonlinear behavior of neuronal systems except for extremely large synaptic inputs. Thus, neurons have two distinct linear and quadratic functions, which shows that piecewise linear?+?quadratic analysis is much more complete than just piecewise linear analysis; in addition quadratic analysis can be done at a single holding potential. Furthermore, the nonlinear neuronal responses contain more frequencies over a wider frequency band than the input signal. As a consequence, they convert limited amplitude and bandwidth input signals to wider bandwidth and more complex output responses. Finally, simulations at subthreshold membrane potentials with realistic PHN neuron models suggest that the quadratic functions are fundamentally dominated by active dendritic structures and persistent sodium conductances. PMID:23519443

  12. PERCEPTUAL NORMALIZATION OF VOWELS PRODUCED BY SINUSOIDAL VOICES*

    E-print Network

    . The present study, employing sinusoidal signals, raised this issue by testing the identification of target Ib of their component tones. Vowel quality of target syllables was influenced by this acoustic correlate of vocal of a sentence, they perceive linguistic properties despite the absence of short-time acoustic components typical

  13. Parameter estimation of exponentially damped sinusoids using higher order statistics

    Microsoft Academic Search

    C. K. Papadopoulos; C. L. Nikias

    1990-01-01

    A new approach for the estimation of the parameters of exponentially damped sinusoids is introduced based on third- or fourth-order statistics of the observation signal. The method may be seen as an extension of the minimum norm principal eigenvectors method to higher order statistics domains. The strong points and limitations of the method are discussed as well as sufficient conditions

  14. Emotions and Voice Quality: Experiments with Sinusoidal Modeling

    Microsoft Academic Search

    Carlo Drioli; Graziano Tisato; Piero Cosi; Fabio Tesser

    Voice quality is recognized to play an important role for the rendering of emotions in verbal communication. In this paper we explore the effectiveness of a sinusoidal modeling process- ing framework for voice transformations finalized to the anal- ysis and synthesis of emotive speech. A set of acoustic cues is selected to compare the voice quality characteristics of the speech

  15. An automated system for measuring parameters of nematode sinusoidal movement

    Microsoft Academic Search

    Christopher J Cronin; Jane E Mendel; Saleem Mukhtar; Young-Mee Kim; Robert C Stirbl; Jehoshua Bruck; Paul W Sternberg

    2005-01-01

    BACKGROUND: Nematode sinusoidal movement has been used as a phenotype in many studies of C. elegans development, behavior and physiology. A thorough understanding of the ways in which genes control these aspects of biology depends, in part, on the accuracy of phenotypic analysis. While worms that move poorly are relatively easy to describe, description of hyperactive movement and movement modulation

  16. Sound Representation and Modification With Multiresolution Sinusoidal Models

    E-print Network

    Vetterli, Martin

    Sound Representation and Modification With Multiresolution Sinusoidal Models Michael Goodwin in a multiresolution framework based on adaptive time segmentation; the adaptation is guided by a metric the modehng into a multiresolution framework [3, 5, 6]. This paper is concerned with muftiresolution based

  17. An analysis of Rectifiier with Near Sinusoidal input current

    Microsoft Academic Search

    C. Filote; C. Ciufudean; A. M. Cozgarea

    2009-01-01

    The IEEE-519 and IEC 61000-3 standards limit the individual harmonics current as well as the total harmonic distortion (THD) for nonlinear power electronic loads. We present a comparative study of a classical three-phase rectifier diode (TPRD) and RNSIC rectifier (Rectifier with Near Sinusoidal Currents), with respect to harmonic current distortion. Simulation results are experimentally verified.

  18. Sound waves in two-dimensional ducts with sinusoidal walls

    NASA Technical Reports Server (NTRS)

    Nayfeh, A. H.

    1974-01-01

    The method of multiple scales is used to analyze the wave propagation in two-dimensional hard-walled ducts with sinusoidal walls. For traveling waves, resonance occurs whenever the wall wavenumber is equal to the difference of the wavenumbers of any two duct acoustic modes. The results show that neither of these resonating modes could occur without strongly generating the other.

  19. Variants of rectifiers with near sinusoidal input currents

    Microsoft Academic Search

    M. Pletea; N. R. Buzatu; A. Serediuc; C. Nedelcu; I. V. Pletea

    2011-01-01

    Based on the characteristics of the rectifiers with near sinusoidal input currents (RNSIC-1, with capacitors connected on the DC side and RNSIC-2, with capacitors connected on the AC side), the paper proposes a comparative analysis between the performances of the two variants of RNSIC converters with three- phase six pulse full-bridge diode rectifiers with passive filters. A comparative analysis between

  20. Sinusoidal reaction formulation for radiation and scattering from conducting surfaces

    NASA Technical Reports Server (NTRS)

    Richmond, J. H.; Wang, N.

    1974-01-01

    A piecewise-sinusoidal reaction technique is developed for scattering and radiation from perfectly conducting bodies of arbitrary shape. The theory and numerical results for scattering patterns of rectangular plates and radiation patterns of corner-reflector antennas are presented. Experimental measurements are included for comparison with the calculated data.

  1. A practical implementation of multi-frequency widefield frequency-domain FLIM

    PubMed Central

    Chen, Hongtao

    2013-01-01

    Widefield frequency-domain fluorescence lifetime imaging microscopy (FD-FLIM) is a fast and accurate method to measure the fluorescence lifetime, especially in kinetic studies in biomedical researches. However, the small range of modulation frequencies available in commercial instruments makes this technique limited in its applications. Here we describe a practical implementation of multi-frequency widefield FD-FLIM using a pulsed supercontinuum laser and a direct digital synthesizer. In this instrument we use a pulse to modulate the image intensifier rather than the more conventional sine wave modulation. This allows parallel multi-frequency FLIM measurement using the Fast Fourier Transform and the cross-correlation technique, which permits precise and simultaneous isolation of individual frequencies. In addition, the pulse modulation at the cathode of image intensifier restored the loss of optical resolution caused by the defocusing effect when the voltage at the cathode is sinusoidally modulated. Furthermore, in our implementation of this technique, data can be graphically analyzed by the phasor method while data are acquired, which allows easy fit-free lifetime analysis of FLIM images. Here our measurements of standard fluorescent samples and a Föster resonance energy transfer pair demonstrate that the widefield multi-frequency FLIM system is a valuable and simple tool in fluorescence imaging studies. PMID:23296945

  2. Spectral and temporal properties of optical signals with multiple sinusoidal phase modulations.

    PubMed

    Dorrer, C

    2014-02-10

    Optical signals generated by multiple sinusoidal temporal phase modulations (multi-FMs) applied to a monochromatic field are studied from the viewpoint of their optical spectrum and temporal modulations arising from spectral impairments. Statistical analysis based on the central limit theorem shows that the signals' optical spectrum converges to a normal distribution as the number of modulations increases, allowing one to predict the frequency range containing a given fraction of the total energy with the associated cumulative density function. The conversion of frequency modulation to amplitude modulation is analyzed and simulated for arbitrary multi-FM signals. These developments are of theoretical and practical importance for high-energy laser systems, where optical pulses are phase modulated in the front end to smooth out the on-target beam profile and prevent potentially catastrophic damage to optical components. PMID:24663283

  3. Accuracy assessment of the two-sample zero-crossing detection in a sinusoidal signal

    NASA Astrophysics Data System (ADS)

    Svitlov, S.; Rothleitner, Ch; Wang, L. J.

    2012-08-01

    The accuracy of a two-sample zero-crossing detection method is assessed by analytical uncertainty propagation and is verified in numerical simulations. Approximated expressions are given to evaluate uncertainty components due to linear interpolation, quantization, white noise and time jitter. The combined standard uncertainty of a detected zero phase is expressed as a function of the signal frequency, power of external noise and parameters of the digitizer used. The evaluation of the uncertainty of the measurand, derived from several detected zero-crossings, is illustrated with applications in frequency, displacement and free-fall acceleration measurements. The reported results can be used for uncertainty analysis and parameter optimization of a measurement system or a procedure, involving processing of sinusoidal signals.

  4. Non-visually induced smooth pursuit eye movements using sinusoidal target motion.

    PubMed

    Hashiba, M; Matsuoka, T; Baba, S; Watanabe, S

    1996-01-01

    Non-visually induced smooth pursuit eye movements (SPEM) were assessed in 8 healthy subjects. Targets were the subjects finger tip movements as somatosensory stimulus and a moving sound source as acoustic stimulus. Horizontal sinusoidal target movements were provided at an amplitude of 15 degrees and frequencies of 0.2, 0.4 and 0.8 Hz. In comparison with conventional visually-induced SPEM, low gain and phase lead were observed, particularly at higher frequency target movements. There was considerable inter-individual variability in the non-visual SPEM performance. A positive correlation between the gains of somatosensory and acoustic SPEM was observed in each subject. We suggest a common SPEM generator, including predictive control for the non-visual SPEM and to some extent for the visual SPEM. PMID:8908293

  5. Relative stability of dynamical states and stochastic resonance in a sinusoidal potential.

    PubMed

    Reenbohn, W L; Mahato, Mangal C

    2013-09-01

    Recently, stochastic resonance was shown to occur in underdamped periodic potentials at frequencies (of the drive field) close to the natural frequency at the minima of the potentials. In these systems the particle trajectories are not arbitrary at low temperatures but follow the drive field with two definite mean phase differences depending on the initial conditions. The trajectories are thus found to be in only two stable dynamical states. The occurrence of stochastic resonance in the periodic potentials was explained as a consequence of the transitions between these two dynamical states as the temperature was increased. In the present work, we find the range of amplitudes of the drive field over which the dynamical states could be observed in a sinusoidal potential. The variation of the relative stability of the dynamical states as a function of drive-field amplitude is clarified by analyzing the nature of curves characterizing the stochastic resonance as the amplitude is varied within the range. PMID:24125249

  6. The Use of Harmonic Distortion to Increase the Output Voltage of a Three-Phase PWM Inverter

    Microsoft Academic Search

    John A. Houldsworth; Duncan A. Grant

    1984-01-01

    By adding a measure of third harmonic to the output of each phase of a three-phase inverter, it is possible to obtain a line-to-line output voltage that is 15 percent greater than that obtainable when pure sinusoidal modulation is employed. The line-to-line voltage is undistorted. The method permits the inverter to deliver an output voltage approximately equal to the voltage

  7. A novel SVPWM strategy considering DC-link balancing for a multi-level voltage source inverter

    Microsoft Academic Search

    Yo-Han Lee; Rae-Young Kim; Dong-Seok Hyun

    1999-01-01

    This paper proposes a novel SVPWM (space vector pulse width modulation) strategy for a multi-level voltage source inverter. This strategy is easily implemented as SPWM (sinusoidal pulse width modulation) and has the same DC-link voltage utilization as the general SVPWM scheme. The method to keep the voltage balance of the DC-link is also proposed by the analysis of DC-link voltage

  8. Time-frequency analysis of very fast transient over voltages for effective shielding of control circuits in a 245kv gas Insulated Substation

    Microsoft Academic Search

    J. V. G. Rama Rao; J. Amarnath; S. Kamakshaiah

    2010-01-01

    Very fast transient over voltages (VFTO) and very fast transient over currents (VFTC) are generated during switching operation of disconnectors in Gas insulated substation (GIS). In this paper the accurate GIS model has been developed and VFTO'S and VFTC'S were estimated at bushing termination using EMTP program. The wavelet analysis of VFTO and VFTC signals have been carried out and

  9. Application of Matrix Converter to Low-Voltage and Large-Current DC Power Supply with High-Frequency AC Link

    E-print Network

    Fujimoto, Hiroshi

    TER-06-25 SPC-06-72 Application of Matrix Converter to Low-Voltage and Large-Current DC Power of Technology) This paper describes an application of a matrix converter to a 13-V and 2500-A DC power supply, using a 15-kHz transformer coupling. The matrix converter generates 15 kHz single-phase current

  10. Study of the generator/motor operation of induction machines in a high frequency link space power system

    NASA Technical Reports Server (NTRS)

    Lipo, Thomas A.; Sood, Pradeep K.

    1987-01-01

    Static power conversion systems have traditionally utilized dc current or voltage source links for converting power from one ac or dc form to another since it readily achieves the temporary energy storage required to decouple the input from the output. Such links, however, result in bulky dc capacitors and/or inductors and lead to relatively high losses in the converters due to stresses on the semiconductor switches. The feasibility of utilizing a high frequency sinusoidal voltage link to accomplish the energy storage and decoupling function is examined. In particular, a type of resonant six pulse bridge interface converter is proposed which utilizes zero voltage switching principles to minimize switching losses and uses an easy to implement technique for pulse density modulation to control the amplitude, frequency, and the waveshape of the synthesized low frequency voltage or current. Adaptation of the proposed topology for power conversion to single-phase ac and dc voltage or current outputs is shown to be straight forward. The feasibility of the proposed power circuit and control technique for both active and passive loads are verified by means of simulation and experiment.

  11. Prediction of spectral shifts proportional to source distances by time-varying frequency or wavelength selection

    Microsoft Academic Search

    V. Guruprasad

    2008-01-01

    Any frequency selective device with an ongoing drift will cause observed spectra to be variously and simultaneously scaled in proportion to their source distances. The reason is that detectors after the drifting selection will integrate instantaneous electric or magnetic field values from successive sinusoids, and these sinusoids would differ in both frequency and phase. Phase differences between frequencies are ordinarily

  12. Fourier Analysis of Sinusoidally Driven Thalamocortical Relay Neurons and a Minimal Integrate-and-Fire-or-Burst Model

    E-print Network

    Sherman, S. Murray

    Fourier Analysis of Sinusoidally Driven Thalamocortical Relay Neurons and a Minimal Integrate. Fourier analysis of sinusoidally driven thalamocortical relay neurons and a minimal integrate and burst firing modes to sinusoidal current injection and performed Fourier analysis on these responses

  13. Investigation of Calibrating Force Transducer Using Sinusoidal Force

    SciTech Connect

    Zhang Li [School of Instrumentation Science and Opto-electronics Engineering, Beihang University, Beijing (China); Key Laboratory for Metrology, Changcheng Institute of Metrology and Measurement (CIMM), Beijing 100095 (China); Wang Yu; Zhang Lizhe [Key Laboratory for Metrology, Changcheng Institute of Metrology and Measurement (CIMM), Beijing 100095 (China)

    2010-05-28

    Sinusoidal force calibration method was studied several years before at Physikalisch-Technische Bundesanstalt (PTB). A similar dynamic force calibration system is developed at Changcheng Institute of Metrology and Measurement (CIMM). It uses electro-dynamic shakers to generate dynamic force in the range from 1 N to 20 kN, and heterodyne laser interferometers are used for acceleration measurement. The force transducer to be calibrated is mounted on the shaker, and a mass block is screwed on the top of force transducer, the sinusoidal forces realized by accelerated load masses are traceable to acceleration and mass according to the force definition. The methods of determining Spatial-dependent acceleration on mass block and measuring the end mass of force transducer in dynamic force calibration are discussed in this paper.

  14. Sinusoidal input describing function for hysteresis followed by elementary backlash

    NASA Technical Reports Server (NTRS)

    Ringland, R. F.

    1976-01-01

    The author proposes a new sinusoidal input describing function which accounts for the serial combination of hysteresis followed by elementary backlash in a single nonlinear element. The output of the hysteresis element drives the elementary backlash element. Various analytical forms of the describing function are given, depending on the a/A ratio, where a is the half width of the hysteresis band or backlash gap, and A is the amplitude of the assumed input sinusoid, and on the value of the parameter representing the fraction of a attributed to the backlash characteristic. The negative inverse describing function is plotted on a gain-phase plot, and it is seen that a relatively small amount of backlash leads to domination of the backlash character in the describing function. The extent of the region of the gain-phase plane covered by the describing function is such as to guarantee some form of limit cycle behavior in most closed-loop systems.

  15. Estimating Transmissivity from the Water Level Fluctuations of a Sinusoidally Forced Well

    USGS Publications Warehouse

    Mehnert, E.; Valocchi, A.J.; Heidari, M.; Kapoor, S.G.; Kumar, P.

    1999-01-01

    The water levels in wells are known to fluctuate in response to earth tides and changes in atmospheric pressure. These water level fluctuations can be analyzed to estimate transmissivity (T). A new method to estimate transmissivity, which assumes that the atmospheric pressure varies in a sinusoidal fashion, is presented. Data analysis for this simplified method involves using a set of type curves and estimating the ratio of the amplitudes of the well response over the atmospheric pressure. Type curves for this new method were generated based on a model for ground water flow between the well and aquifer developed by Cooper et al. (1965). Data analysis with this method confirmed these published results: (1) the amplitude ratio is a function of transmissivity, the well radius, and the frequency of the sinusoidal oscillation; and (2) the amplitude ratio is a weak function of storativity. Compared to other methods, the developed method involves simpler, more intuitive data analysis and allows shorter data sets to be analyzed. The effect of noise on estimating the amplitude ratio was evaluated and found to be more significant at lower T. For aquifers with low T, noise was shown to mask the water level fluctuations induced by atmospheric pressure changes. In addition, reducing the length of the data series did not affect the estimate of T, but the variance of the estimate was higher for the shorter series of noisy data.

  16. Increased sinusoidal volume and solute extraction during retrograde liver perfusion

    SciTech Connect

    Bass, N.M.; Manning, J.A.; Weisiger, R.A.

    1989-06-01

    Retrograde isolated liver perfusion has been used to probe acinar functional heterogeneity, but the hemodynamic effects of backward flow have not been characterized. In this study, extraction of a long-chain fatty acid derivative, 12-N-methyl-7-nitrobenzo-2-oxa-1,3-diazol-amino stearate (12-NBDS), was greater during retrograde than during anterograde perfusion of isolated rat liver. To determine whether hemodynamic differences between anterograde and retrograde perfused livers could account for this finding, the hepatic extracellular space was measured for both directions of flow by means of (/sup 14/C)sucrose washout during perfusion as well as by direct measurement of (/sup 14/C)sucrose entrapped during perfusion. A three- to fourfold enlargement of the total hepatic extracellular space was found during retrograde perfusion by both approaches. Examination of perfusion-fixed livers by light microscopy and morphometry revealed that marked distension of the sinusoids occurred during retrograde perfusion and that this accounts for the observed increase in the (/sup 14/C)sucrose space. These findings support the hypothesis that maximum resistance to perfusate flow in the isolated perfused rat liver is located at the presinusoidal level. In addition, increased transit time of perfusate through the liver and greater sinusoidal surface area resulting from sinusoidal distension may account for the higher extraction of 12-NBDS and possibly other compounds by retrograde perfused liver.

  17. The sinusoidal probe: a new approach to improve electrode longevity.

    PubMed

    Sohal, Harbaljit S; Jackson, Andrew; Jackson, Richard; Clowry, Gavin J; Vassilevski, Konstantin; O'Neill, Anthony; Baker, Stuart N

    2014-01-01

    Micromotion between the brain and implanted electrodes is a major contributor to the failure of invasive brain-machine interfaces. Movements of the electrode tip cause recording instabilities while spike amplitudes decline over the weeks/months post-implantation due to glial cell activation caused by sustained mechanical trauma. We have designed a sinusoidal probe in order to reduce movement of the recording tip relative to the surrounding neural tissue. The probe was microfabricated from flexible materials and incorporated a sinusoidal shaft to minimize tethering forces and a 3D spheroid tip to anchor the recording site within the brain. Compared to standard microwire electrodes, the signal-to-noise ratio and local field potential power of sinusoidal probe recordings from rabbits was more stable across recording periods up to 678 days. Histological quantification of microglia and astrocytes showed reduced neuronal tissue damage especially for the tip region between 6 and 24 months post-implantation. We suggest that the micromotion-reducing measures incorporated into our design, at least partially, decreased the magnitude of gliosis, resulting in enhanced longevity of recording. PMID:24808859

  18. Detectability of Radio Frequency Interference due to Spread Spectrum Communication Signals using the

    E-print Network

    Ruf, Christopher

    Detectability of Radio Frequency Interference due to Spread Spectrum Communication Signals using-- Analysis of detectability of the kurtosis algorithm for pulsed-sinusoidal Radio Frequency Interference (RFI. Index terms ­ Microwave radiometry, radio frequency interference I. INTRODUCTION easurements made

  19. High bias voltage effect on spin-dependent conductivity and low frequency noise in epitaxial Fe\\/MgO\\/Fe magnetic tunnel junctions

    Microsoft Academic Search

    Farkhad Aliev; Ruben Guerrero; David Herranz; Raul Villar; Fanny Greullet; Coriolan Tiusan; Michel Hehn; Francois Montaigne

    2008-01-01

    Low temperature (10K) high voltage bias dynamic conductivity (up to 2.7V) and shot noise (up to 1V) were studied in epitaxial Fe(100)\\/Fe-C\\/MgO(100)\\/Fe(100) magnetic tunnel junctions, as a function of the magnetic state. The MTJs show large TMR (185% at 300K and 330% at 4K). Multiple sign inversion of the magnetoresistance is observed for bias polarity when the electrons scan the

  20. Zero-voltage-switching multi-resonant technique-a novel approach to improve performance of high frequency quasi-resonant converters

    Microsoft Academic Search

    W. A. Tabisz; Fred C. LEE

    1988-01-01

    The power transistor in zero-current-switched quasiresonant converters (ZCS-QRCs) suffers from excessive voltage stress, and the converter regulation characteristics and stability are adversely affected by parasitic oscillations caused by the junction capacitance of the rectifying diode. A novel, multiresonant switch concept is proposed to overcome these problems. A unique multiresonant network arrangement results in absorption of all parasitic components, including transistor

  1. Emissive Probe Measurements in a Dual-Frequency-Confined Capacitively-Coupled-Plasma System

    NASA Astrophysics Data System (ADS)

    Linnane, Shane; Ellingboe, Albert R.

    2002-10-01

    Dual frequency confined capacitively coupled plasmas (DFC-CCP) are increasingly used in semiconductor manufacturing for dielectric etching, allowing greater (and independent) control of ion energies and ion flux on the etched substrate. The powered electrode is driven with the summation of 27MHz and 2MHz sinusoidal voltages, while the other electrode is grounded. The electrode areas are similar in size, giving an electrode aspect ratio less than 2. Because of this low aspect ratio, there are large oscillations in the plasma potential. The expectation is for sinusoidal oscillations at the higher driving frequency, due to capacitive sheaths, while a rectified oscillation is expected at the lower driving frequency.(E. Kawamura, V. Vahedi, M. A. Lieberman and C. K. Birdsall, Plasma Sources Sci. Technology. 8 (1999) R45-R64 Work Supported by EURATOM.) Measurements of rf oscillation in the plasma potential taken with a floating emissive probe will be presented. The emissive probe and circuitry allows direct realtime measurement of plasma potential oscillation at both driving frequencies and the harmonics of each, thus allowing measurement of the actual potential on the driven electrode and ion energy incident on grounded electrode.

  2. Calculation and Compilation of the Unsteady-lift Functions for a Rigid Wing Subjected to Sinusoidal Gusts and to Sinusoidal Sinking Oscillations

    NASA Technical Reports Server (NTRS)

    Drischler, Joseph A

    1956-01-01

    The total lift responses to sinusoidal sinking oscillations and to sinusoidal gusts have been calculated, largely from existing information, for wings of various plan forms in subsonic and supersonic flow. For most of the cases considered, closed-form expressions are given and the final results are presented in the form of plots of the square of the modulus of the lift coefficient for wings in a sinusoidally oscillating gust field and in the form of the real and imaginary parts of the lift coefficient for wings undergoing sinusoidal sinking oscillations.

  3. Dual Duty Cycle Controlled Voltage Source Soft-Switching High Frequency Inverter with AC Load Side Reverse Blocking Switched Resonant Capacitor

    Microsoft Academic Search

    Khairy Fathy; Ju-Sung Kang; H. Ogiwara; B. Eiuo; H. Omori; Hyun Woo Lee; M. Nakaoka

    2006-01-01

    This paper presents a new ZVT-PWM high frequency inverter. The ZVT operation is achieved in the hole load range by using a simple auxiliary reverse blocking switch in parallel with series resonant capacitor dual duty cycle is used to provide a wide range of output power regulation which is important in many high frequency inverter applications. It is more suitable

  4. Response Linearity of Alert Monkey Non-Eye Movement Vestibular Nucleus Neurons During Sinusoidal Yaw Rotation

    PubMed Central

    Newlands, Shawn D.; Lin, Nan; Wei, Min

    2009-01-01

    Vestibular afferents display linear responses over a range of amplitudes and frequencies, but comparable data for central vestibular neurons are lacking. To examine the effect of stimulus frequency and magnitude on the response sensitivity and linearity of non-eye movement central vestibular neurons, we recorded from the vestibular nuclei in awake rhesus macaques during sinusoidal yaw rotation at frequencies between 0.1 and 2 Hz and between 7.5 and 210°/s peak velocity. The dynamics of the neurons' responses across frequencies, while holding peak velocity constant, was consistent with previous studies. However, as the peak velocity was varied, while holding the frequency constant, neurons demonstrated lower sensitivities with increasing peak velocity, even at the lowest peak velocities tested. With increasing peak velocity, the proportion of neurons that silenced during a portion of the response increased. However, the decrease in sensitivity of these neurons with higher peak velocities of rotation was not due to increased silencing during the inhibitory portion of the cycle. Rather the neurons displayed peak firing rates that did not increase in proportion to head velocity as the peak velocity of rotation increased. These data suggest that, unlike vestibular afferents, the central vestibular neurons without eye movement sensitivity examined in this study do not follow linear systems principles even at low velocities. PMID:19553479

  5. Using a quadratic parameter sinusoid model to characterize the structure of EEG sleep spindles

    PubMed Central

    Palliyali, Abdul J.; Ahmed, Mohammad N.; Ahmed, Beena

    2015-01-01

    Sleep spindles are essentially non-stationary signals that display time and frequency-varying characteristics within their envelope, which makes it difficult to accurately identify its instantaneous frequency and amplitude. To allow a better parameterization of the structure of spindle, we propose modeling spindles using a Quadratic Parameter Sinusoid (QPS). The QPS is well suited to model spindle activity as it utilizes a quadratic representation to capture the inherent duration and frequency variations within spindles. The effectiveness of our proposed model and estimation technique was quantitatively evaluated in parameter determination experiments using simulated spindle-like signals and real spindles in the presence of background EEG. We used the QPS parameters to predict the energy and frequency of spindles with a mean accuracy of 92.34 and 97.73% respectively. We also show that the QPS parameters provide a quantification of the amplitude and frequency variations occurring within sleep spindles that can be observed visually and related to their characteristic “waxing and waning” shape. We analyze the variations in the parameters values to present how they can be used to understand the inter- and intra-participant variations in spindle structure. Finally, we present a comparison of the QPS parameters of spindles and non-spindles, which shows a substantial difference in parameter values between the two classes. PMID:25999833

  6. Parameters of a Plunger Core Reactor with Parallel Winding Paths Obtained from Voltage Driven Finite Element Analyses

    Microsoft Academic Search

    Erich Schmidt; Peter Hamberger

    2006-01-01

    The steady-state operational parameters of a plunger core reactor with four parallel connected winding paths are calculated from voltage driven finite element analyses. Thereby, the 3D finite element model utilizes a direct circuit coupling to take into account for the applied sinusoidal voltage and the parallel windings paths. Consequently, the distribution of the coil currents is obtained with the full

  7. Comparison of high frequency, high temperature core loss and B-H loop characteristics of an 80 Ni-Fe crystalline alloy and two iron-based amorphous alloys

    NASA Astrophysics Data System (ADS)

    Wieserman, William R.; Schwarze, Gene E.; Niedra, Janis M.

    1991-01-01

    Limited experimental data exists for the specific core loss and dynamic B-H loops for soft magnetic materials for the combined conditions of high frequency and high temperature. This experimental study investigates the specific core loss and dynamic B-H characteristics of a nickel-iron crystalline magnetic alloy (Supermalloy) and two-iron-based amorphous magnetic materials (Metglas 2605S-3A and Metglas 2605SC) over the frequency range of 1-50 kHz and temperature range of 23-300 C under sinusoidal voltage excitation. The effects of maximum magnetic flux density, frequency, and temperature on the specific core loss and on the size and shape of the B-H loops are examined. The Supermalloy and Metglas 2605S-3A and 2605SC data are used to compare the core loss of transformers with identical kVA and voltage ratings.

  8. Comparison of high frequency, high temperature core loss and B-H loop characteristics of an 80 Ni-Fe crystalline alloy and two iron-based amorphous alloys. [Ni; Fe

    SciTech Connect

    Wieserman, W.R. (University of Pittsburgh at Johnstown, Johnstown, Pennsylvania (USA)); Schwarze, G.E. (NASA Lewis Research Center, Cleveland, Ohio (USA)); Niedra, J.M. (Sverdrup Technology, NASA/LeRC Group, Cleveland, Ohio (USA))

    1991-01-10

    Limited experimental data exists for the specific core loss and dynamic B-H loops for soft magnetic materials for the combined conditions of high frequency and high temperature. This experimental study investigates the specific core loss and dynamic B-H characteristics of a nickel-iron crystalline magnetic alloy (Supermalloy) and two-iron-based amorphous magnetic materials (Metglas 2605S-3A and Metglas 2605SC) over the frequency range of 1--50 kHz and temperature range of 23--300 C under sinusoidal voltage excitation. The effects of maximum magnetic flux density, frequency, and temperature on the specific core loss and on the size and shape of the B-H loops are examined. The Supermalloy and Metglas 2605S-3A and 2605SC data are used to compare the core loss of transformers with identical kVA and voltage ratings.

  9. Oscillation of the human ankle joint in response to applied sinusoidal torque on the foot

    PubMed Central

    Agarwal, Gyan C.; Gottlieb, Gerald L.

    1977-01-01

    1. Low-frequency (3-30 Hz) oscillatory rotation of the ankle joint in plantarflexion—dorsiflexion was generated with a torque motor. Torque, rotation about the ankle and electromyograms (e.m.g.s) for the gastrocnemius—soleus and the anterior tibial muscles were recorded. 2. Fourier coefficients at each drive frequency were used to calculate the effective compliance (ratio of rotation and torque). The compliance has a sharp resonance when tonic, voluntary muscle activity is present. 3. The resonant frequency of compliance is between 3 and 8 Hz. The location of the resonant frequency and the magnitude of the compliance at resonance depend upon both the degree of tonic muscle activity and the amplitude of the driving torque. The resonant frequency increases with increasing tonic activity. 4. With tonic muscle activity, the compliance in the frequency range below resonance increases with increasing amplitudes of driving torque. 5. The e.m.g., when evoked by the rhythmic stretch, lags the start of stretching by between 50 and 70 msec. 6. When tonic muscle activity is present, the resonant frequency of the stretch reflex is between 5 and 6·5 Hz. 7. Following the start of driven oscillation at frequencies near resonance, slowly increasing amplitudes of angular rotation (to a limit) are observed. 8. Distortion (from the sinusoidal wave shape) of angular rotation is frequently observed with drive frequencies between 8 and 12 Hz during which there sometimes occur spontaneous recurrences of oscillation at the drive frequency. For the angular rotation, a significant portion of the power may be in subharmonic frequency components of the drive frequency when that frequency is between 8 and 12 Hz. 9. Self-sustaining oscillation (clonus) near the resonant frequency of the compliance is sometimes observed after the modulation signal to the motor is turned off. This is most often seen when the gastrocnemius—soleus muscles are fatigued. Clonus may be evoked by driven oscillation at any frequency. 10. The hypothesis that physiological tremor, which occurs between 8 and 12 Hz, is a consequence of stretch reflex servo properties seems to be at odds with the observations of resonance in the compliance and of self-generated clonus both occurring in the 5-8 Hz region. PMID:874886

  10. The nonideality coefficient of current-voltage characteristics for p-n junctions in a high ultrahigh-frequency (microwave) field

    SciTech Connect

    Shamirzaev, S. H. [Academy of Sciences of Republic of Uzbekistan, Physicotechnical Institute (Uzbekistan)], E-mail: shamir@uzsci.net; Gulyamov, G. [Namangan Engineering-Pedagogical Institute (Uzbekistan); Dadamirzaev, M. G. [Academy of Sciences of Republic of Uzbekistan, Physicotechnical Institute (Uzbekistan); Gulyamov, A. G. [Namangan Engineering-Pedagogical Institute (Uzbekistan)

    2009-01-15

    The effect of heating of electrons and holes on the nonideality coefficient of the current-voltage characteristic for a p-n junction in a high microwave field is studied. It is established that the nonideality coefficient for a diode depends on the type of charge carriers that make the major contribution to the current in the p-n junction. It is shown that, in some cases in silicon samples, the nonideality coefficient for the diode is governed by the temperature for holes in spite of the fact that the temperature for electrons is higher than the temperature for holes.

  11. High-Efficient High Frequency Linked Zero Voltage Soft Switching PWM DC\\/DC Power Converter with ON\\/OFF-Assisted Synchronous Rectifier Scheme

    Microsoft Academic Search

    Shinji Sato; Serguei Moisseev; Manabu Ishitobi; Eiji Hiraki; Mutsuo Nakaoka

    2004-01-01

    Advanced development of the high frequency pulse modulated DC\\/DC power converters are indispensable in order to achieve smaller size, higher performances of the power supplies. In resent years the problems of the electromagnetic noise generation caused by the hard-switching pulse width modulation (PWM)---based high frequency operation of the switching power devices have been significant, including switching losses and switching surges.

  12. Investigation of mica based insulation for high voltage machines subjected to repetitive pulsed voltage

    Microsoft Academic Search

    Fredrik Sahlén; Li Ming; Kenneth Johansson; Eva Mårtensson; Osmo Koponen

    2010-01-01

    The interest in the prediction and qualification of insulation life performance in high voltage machines fed by converters has steadily grown, since the use of these machines is gradually increasing. The voltage stress on the insulation system is different for converter fed machines compared to machines fed online with power frequency voltage. The common interest in this subject has lead

  13. Measurement of n-type Dry Thermally Oxidized 6H-SiC Metal-oxide Semiconductor Diodes by Quasistatic and High-Frequency Capacitance Versus Voltage and Capacitance Transient Techniques

    NASA Technical Reports Server (NTRS)

    Neudeck, P.; Kang, S.; Petit, J.; Tabib-Azar, M.

    1994-01-01

    Dry-oxidized n-type 6H-SiC metal-oxide-semiconductor capacitors are investigated using quasistatic capacitance versus voltage (C-V), high-frequency C-V, and pulsed high-frequency capacitance transient (C-t) analysis over the temperature range from 297 to 573 K. The quasistatic C - V characteristics presented are the first reported for 6H-SiC MOS capacitors, and exhibit startling nonidealities due to nonequilibrium conditions that arise from the fact that the recombination/generation process in 6H-SiC is extraordinarily slow even at the highest measurement temperature employed. The high-frequency dark C-V characteristics all showed deep depletion with no observable hysteresis. The recovery of the high-frequency capacitance from deep depletion to inversion was used to characterize the minority-carrier generation process as a function of temperature. Zerbst analysis conducted on the resulting C-t transients, which were longer than 1000 s at 573 K, showed a generation lifetime thermal activation energy of 0.49 eV.

  14. Construction of a low-frequency high-power piezoelectric transformer with a specified step-up voltage transformation ratio using two identical bolt-clamped Langevin-type transducers

    NASA Astrophysics Data System (ADS)

    Adachi, Kazunari; Konno, Takuma; Kosugi, Satoshi

    2015-06-01

    We propose a low-frequency piezoelectric transformer comprising two identical bolt-clamped Langevin-type transducers (BLTs) and a stepped horn with a half-wavelength straight extension. The transformer can realize a specified step-up voltage transformation ratio as determined by the cross-sectional area ratio of the horn whose both ends the two BLTs are connected to, and the driving frequency at which the specified transformation ratio is realized can be set near its mechanical resonance. Thus, it can be mechanically held firmly at its vibratory node without affecting the mechanical vibration mode or resulting in a loss of energy. After relevant finite-element simulations, experiments were conducted for a trial-fabricated transformer of the above type. As a result, the experimental results predicted by the simulations were obtained in step-up operation. The influence of the load resistance on the deviation of the driving frequency from its total mechanical resonance of 53.1 kHz was found to be less than 130 Hz (0.24% of the resonance frequency) only. High-power performance of the piezoelectric transformer was also demonstrated.

  15. Cell shape-dependent rectification of surface receptor transport in a sinusoidal electric field.

    PubMed Central

    Lee, R C; Gowrishankar, T R; Basch, R M; Patel, P K; Golan, D E

    1993-01-01

    In the presence of an extracellular electric field, transport dynamics of cell surface receptors represent a balance between electromigration and mutual diffusion. Because mutual diffusion is highly dependent on surface geometry, certain asymmetrical cell shapes effectively create an anisotropic resistance to receptor electromigration. If the resistance to receptor transport along a single axis is anisotropic, then an applied sinusoidal electric field will drive a net time-average receptor displacement, effectively rectifying receptor transport. To quantify the importance of this effect, a finite difference mathematical model was formulated and used to describe charged receptor transport in the plane of a plasma membrane. Representative values for receptor electromigration mobility and diffusivity were used. Model responses were examined for low frequency (10(-4)-10 Hz) 10-V/cm fields and compared with experimental measurements of receptor back-diffusion in human fibroblasts. It was found that receptor transport rectification behaved as a low-pass filter; at the tapered ends of cells, sinusoidal electric fields in the 10(-3) Hz frequency range caused a time-averaged accumulation of receptors as great as 2.5 times the initial uniform concentration. The extent of effective rectification of receptor transport was dependent on the rate of geometrical taper. Model studies also demonstrated that receptor crowding could alter transmembrane potential by an order of magnitude more than the transmembrane potential directly induced by the field. These studies suggest that cell shape is important in governing interactions between alternating current (ac) electric fields and cell surface receptors. PMID:8381681

  16. The forces generated at the human elbow joint in response to imposed sinusoidal movements of the forearm

    PubMed Central

    Joyce, G. C.; Rack, Peter M. H.; Ross, H. F.

    1974-01-01

    1. The mechanical resistance of the human forearm has been measured during imposed sinusoidal flexion-extension movements of the elbow joint. 2. The force required to move the limb can be divided into components required to move the mass, and components required to overcome the resistance offered by elastic and frictional properties of the muscles and other soft tissues. 3. When during a vigorous flexing effort the limb was subjected to a small amplitude sinusoidal movement each extension was followed by a considerable reflex contraction of the flexor muscles. At low frequencies of movement this reflex provided an added resistance to extension, but at 8-12 Hz the delay in the reflex pathway was such that the reflex response to extension occurred after the extension phase of the movement was over and during the subsequent flexion movement. The reflex activity then assisted the movement whereas at other frequencies it impeded it. 4. The reflex response to movement increased as the subject exerted a greater flexing force. 5. Small movements generated a relatively larger reflex response than big ones. 6. Even with large amplitudes of movement when the reflex activity was relatively small, the limb resisted extension with a high level of stiffness; this was comparable with the short range stiffness of muscles in experimental animals. 7. The fact that at some frequencies the reflex response assisted the movement implies that with appropriate loading the limb could undergo a self-sustaining oscillation at those frequencies. PMID:4420490

  17. Integrated Optical Voltage Probe

    NASA Astrophysics Data System (ADS)

    Cordero-Iannarella, R. F.; Yao, S. K.; Thaniyavarn, S.; Findakly, T.; Hayward, G.; Chen, B.

    1983-11-01

    We have designed and tested a guided wave optical modulator for applications as an integrated optical voltage probe. This voltage probe consists of an injection laser diode (ILD) connected to a stress-induced polarization preserving fiber, an electro-optic coupled-channel waveguide modulator, a graded-index multimode fiber for the return optical signal, and an electronics box containing the necessary electronics for the driving of the ILD source and the detection of the return signal. The electronics box can be physically separated from the ILD source and the fiber-modulator assemblies for ease of installation in the field. The ILD and modulator assemblies are ruggedized and the fibers are cabled. This probe has been tested in the frequency range 10 kHz-200 MHz and at a dynamic range of 40 dB at 200 MHz bandwidth.

  18. Organization of flux line system and voltage oscillations in superconducting MgB2

    NASA Astrophysics Data System (ADS)

    Kiliç, A.; Oluta?, M.; Kiliç, K.; Altinkok, A.

    2011-12-01

    The influence of bidirectional square wave (BSW) current on the evolution of the V-t curves was studied in a polycrystalline sample of MgB2. Regular sinusoidal-like voltage oscillations were observed at well-defined values of the amplitude (IBSW) and period (PI) of the BSW current, temperature, and external magnetic field. The voltage oscillations were interpreted mainly in terms of short- and long-range spatial correlations in a flux line system, relaxation effects, and the dynamic competition between pinning and depinning. The oscillating mode was also discussed in terms of sliding charge density waves associated with density fluctuations. Alternatively, the coupling between conventional thermally activated flux creep theory and annealing of the disordered states was considered as another possible mechanism in describing the voltage oscillations. Due to the complex interplay of pinning and driving forces, the oscillating mode is correlated to the drifting of flux lines, which are in motion, and it is assumed that the majority of flux lines try to traverse the sample, but do not leave it entirely. The symmetry in voltage oscillations was attributed to the equality between flux exit and entry along the sample edges. In this process, the majority of flux lines leave the sample and the direction of motion of flux lines reverses. During the oscillatory motion, we suggest that the interaction between flux lines and pinning centers may be elastic coupling in nature, because of rigidity of the flux line lattice in MgB2. Non-oscillatory behavior of V-t curves measured for BSW drive with low PI was attributed pre-dominantly to the effect of pinning on the distribution of the flux lines. The vortex capacitor model could be applied to explain the voltage decays in these V-t curves. However, the voltage decays associated with switching of IBSW to dc current (Idc) were correlated to current-induced quenched disorder and to the glassy state relaxation. Further, angular dependence of voltage oscillations reveals that the anisotropic effects are nearly negligible on the evolution of V-t curves. It was shown that the voltage oscillations can be described well by an empirical expression V(t) ˜ sin(wt + ?), where w is the frequency and ? is the phase angle. Finally, at well-defined values of IBSW and PI of BSW current, H, and T, it was argued that the MgB2 sample behaves like a double-integrator.

  19. Pharmacokinetic modeling of the sinusoidal efflux of anionic ligands from the isolated perfused rat liver: The influence of albumin

    Microsoft Academic Search

    Johannes H. Proost; Henricus M. J. Nijssen; Cornelis B. Strating; Dirk K. F. Meijer; Geny M. M. Groothuis

    1993-01-01

    This study contains a pharmacokinetic analysis on the efflux of organic anions from the liver into the bloodstream (sinusoidal efflux) with specific reference to the influence of albumin. The net sinusoidal efflux rate of dibromosulfophthalein (DBSP) from preloaded livers, being the resultant of sinusoidal efflux and reuptake of ligand by hepatocytes downstream the sinusoid, can be strongly increased by the

  20. Resonant circuit which provides dual-frequency excitation for rapid cycling of an electromagnet

    DOEpatents

    Praeg, W.F.

    1982-03-09

    Disclosed is a novel ring-magnet control circuit that permits synchrotron repetition rates much higher than the frequency of the sinusoidal guide field of the ring magnet during particle acceleration. The control circuit generates sinusoidal excitation currents of different frequencies in the half waves. During radio-frequency acceleration of the synchrotron, the control circuit operates with a lower frequency sine wave and, thereafter, the electromagnets are reset with a higher-frequency half sine wave.

  1. Design and fabrication of nano-sinusoid LSPR devices.

    PubMed

    Mortazavi, Daryoush; Kouzani, Abbas; Kalani, Mahshid

    2014-08-11

    Applications of LSPR nano-particles in various areas of solar cells, LSPR biosensors, and SERS biosensors, based on interaction of light with noble metal nano-particles is increasing. Therefore, design and nano-fabrication of the LSPR devices is a key step in developing such applications. Design of nano-structures with desirable spectral properties using numerical techniques such as finite difference time domain (FDTD) is the first step in this work. A new structure called nano-sinusoid, satisfying the some desirable LSPR characteristics, is designed and simulated using the FDTD method. In the next stage, analytical method of electro static eigen mode method is used to validate the simulation results. The, nano-fabrications method of electron beam lithography (EBL) is implemented to fabricate the proposed profile with high precision. Finally, atomic force microscopy (AFM) is used to investigate the shape of the fabricated nano-particles, and the dark field microscopy is employed to demonstrate the particular spectral characteristics of the proposed nano-sinusoids. PMID:25320975

  2. A new type of STATCOM based on cascading voltage-source inverters with phase-shifted unipolar SPWM

    Microsoft Academic Search

    Yiqiao Liang; C. O. Nwankpa

    1999-01-01

    In this paper, a new type of static compensator (STATCOM) is proposed. This new STATCOM is constructed by cascading several identical full-bridge (H bridge) voltage-source inverters (VSIs). A so-called phase-shifted sinusoidal pulsewidth modulation (SPWM) unipolar voltage switching scheme is applied to control the switching devices of each VSI. The harmonics in STATCOM current caused by the DC voltage ripple is

  3. High-Speed Single-Photon Detection Using 2GHz Sinusoidally Gated InGaAs\\/InP Avalanche Photodiode

    Microsoft Academic Search

    Naoto Namekata; Shunsuke Adachi; Shuichiro Inoue

    2009-01-01

    We report a telecom-band single-photon detector for high-speed quantum key distribution systems. The single-photon detector\\u000a is based on a sinusoidally gated InGaAs\\/InP avalanche photodiode. The gate repetition frequency of the single-photon detector\\u000a reached 2 GHz. A quantum efficiency of 10.5 % at 1550 nm was obtained with a dark count probability per gate of 6.1×10??7 and an afterpulsing probability of

  4. Stream Segregation in the Perception of Sinusoidally Amplitude-Modulated Tones

    PubMed Central

    Dolležal, Lena-Vanessa; Beutelmann, Rainer; Klump, Georg M.

    2012-01-01

    Amplitude modulation can serve as a cue for segregating streams of sounds from different sources. Here we evaluate stream segregation in humans using ABA- sequences of sinusoidally amplitude modulated (SAM) tones. A and B represent SAM tones with the same carrier frequency (1000, 4000 Hz) and modulation depth (30, 100%). The modulation frequency of the A signals (fmodA) was 30, 100 or 300 Hz, respectively. The modulation frequency of the B signals was up to four octaves higher (?fmod). Three different ABA- tone patterns varying in tone duration and stimulus onset asynchrony were presented to evaluate the effect of forward suppression. Subjects indicated their 1- or 2-stream percept on a touch screen at the end of each ABA- sequence (presentation time 5 or 15 s). Tone pattern, fmodA, ?fmod, carrier frequency, modulation depth and presentation time significantly affected the percentage of a 2-stream percept. The human psychophysical results are compared to responses of avian forebrain neurons evoked by different ABA- SAM tone conditions [1] that were broadly overlapping those of the present study. The neurons also showed significant effects of tone pattern and ?fmod that were comparable to effects observed in the present psychophysical study. Depending on the carrier frequency, modulation frequency, modulation depth and the width of the auditory filters, SAM tones may provide mainly temporal cues (sidebands fall within the range of the filter), spectral cues (sidebands fall outside the range of the filter) or possibly both. A computational model based on excitation pattern differences was used to predict the 50% threshold of 2-stream responses. In conditions for which the model predicts a considerably larger 50% threshold of 2-stream responses (i.e., larger ?fmod at threshold) than was observed, it is unlikely that spectral cues can provide an explanation of stream segregation by SAM. PMID:22984436

  5. Method of barrier voltages in cyclic accelerators

    NASA Astrophysics Data System (ADS)

    Meshkov, I. N.

    2014-03-01

    Principle of operation of barrier RF voltage systems that are used for stacking and acceleration of charged particles in proton synchrotrons and storage rings is presented. The description is based on two sample models of such systems: with rectangular and quasi-sinusoidal barriers. Two different methods are used for description of particle dynamics in synchrotrons with barrier RF voltage. The first method is "stepwise" analysis of particle motion in the "momentum-phase" space. This method allows to give a clear and simple description of physical principles of the method and to obtain its main properties in analytical form. However, this method is not always efficient. Therefore, a method of analysis of phase motion of particles in barrier systems based on solution of differential equations of phase motion is presented in the paper and is widely used in practice. This method allows both analytical calculations and numeric simulation, which is illustrated with the aid of supplied examples.

  6. Analysis and Design of a Current-Fed Resonant Inverter for Sinusoidal Excitation of Magnetic Components in the Megahertz Range

    Microsoft Academic Search

    Georgios S. Dimitrakakis; Emmanuel C. Tatakis

    2011-01-01

    This paper deals with the theoretical analysis and construction of an inverter that is suitable as an excitation source for high-frequency measurements (up to 1.3 MHz) on magnetic components. Quantities as output current, operation frequency range, and harmonic content of the output voltage are discussed. The interaction between the power part and the control circuit is investigated by experimental verification

  7. A combined patch-clamp and electrorotation study of the voltage- and frequency-dependent membrane capacitance caused by structurally dissimilar lipophilic anions.

    PubMed

    Zimmermann, D; Kiesel, M; Terpitz, U; Zhou, A; Reuss, R; Kraus, J; Schenk, W A; Bamberg, E; Sukhorukov, V L

    2008-01-01

    Interactions of structurally dissimilar anionic compounds with the plasma membrane of HEK293 cells were analyzed by patch clamp and electrorotation. The combined approach provides complementary information on the lipophilicity, preferential affinity of the anions to the inner/outer membrane leaflet, adsorption depth and transmembrane mobility. The anionic species studied here included the well-known lipophilic anions dipicrylamine (DPA(-)), tetraphenylborate (TPB(-)) and [W(2)(CO)(10)(S(2)CH)](-), the putative lipophilic anion B(CF(3))(4)(-) and three new heterocyclic W(CO)(5) derivatives. All tested anions partitioned strongly into the cell membrane, as indicated by the capacitance increase in patch-clamped cells. The capacitance increment exhibited a bell-shaped dependence on membrane voltage. The midpoint potentials of the maximum capacitance increment were negative, indicating the exclusion of lipophilic anions from the outer membrane leaflet. The adsorption depth of the large organic anions DPA(-), TPB(-) and B(CF(3))(4)(-) increased and that of W(CO)(5) derivatives decreased with increasing concentration of mobile charges. In agreement with the patch-clamp data, electrorotation of cells treated with DPA(-) and W(CO)(5) derivatives revealed a large dispersion of membrane capacitance in the kilohertz to megahertz range due to the translocation of mobile charges. In contrast, in the presence of TPB(-) and B(CF(3))(4)(-) no mobile charges could be detected by electrorotation, despite their strong membrane adsorption. Our data suggest that the presence of oxygen atoms in the outer molecular shell is an important factor for the fast translocation ability of lipophilic anions. PMID:18197354

  8. Programable Driver for Voltage-Controlled Oscillators

    NASA Technical Reports Server (NTRS)

    Fowler, L. E.; Mcneil, J. A.

    1985-01-01

    Electronically programable read-only memory (EPROM) and digital-to-analog converter provide customized time-varying voltage for frequency modulation. Voltage used to modulate IMPATT oscillator that serves as microwave pump for solid-state maser in low-noise amplifier. EPROM simple to tailor voltage waveform to suit characteristics of given maser. Digital information for waveform programed into EPROM chip; digital-to-analog converter reads information and produces corresponding analog wave. Principle readily adapted to other applications.

  9. Predicting iron losses in soft magnetic materials with arbitrary voltage supply: an engineering approach

    Microsoft Academic Search

    Aldo Boglietti; Andrea Cavagnino; Mario Lazzari; Michele Pastorelli

    2003-01-01

    We propose a new approach for predicting iron losses in soft magnetic materials with any voltage supply, starting from the knowledge of the iron losses with a sinusoidal or pulsewidth modulation supply. The model is based on the separation of the loss contributions due to hysteresis, eddy currents, and excess losses with the two supplies. Since any contribution depends on

  10. Deadbeat controlled PWM inverter with parameter estimation using only voltage sensor

    Microsoft Academic Search

    A. Kawamura; T. Haneyoshi; R. G. Hoft

    1988-01-01

    A technique based on deadbeat control theory is proposed to obtain a nearly sinusoidal PWM (pulsewidth-modulated) inverter output voltage using only a voltage sensor. The closed loop sampled-data feedback scheme inherently results in very fast response to load disturbance and nonlinear load, producing low total harmonic distortion. Parameter estimation of the plant provides a type of self-tuning of the proposed

  11. The generalized discontinuous PWM scheme for three-phase voltage source inverters

    Microsoft Academic Search

    Olorunfemi Ojo

    2004-01-01

    This paper presents analytical techniques for the determination of the expressions for the modulation signals used in the carrier-based sinusoidal and generalized discontinuous pulse-width modulation schemes for two-level, three-phase voltage source inverters. The proposed modulation schemes are applicable to inverters generating balanced or unbalanced phase voltages. Some results presented in this paper analytically generalize the several expressions for the modulation

  12. Design and implementation of an FPGA-based control IC for AC-voltage regulation

    Microsoft Academic Search

    Shih-Liang Jung; Meng-Yueh Chang; Jin-Yi Jyang; Li-Chia Yeh; Ying-Yu Tzou

    1999-01-01

    This paper presents a field-programmable gate army (FPGA)-based control integrated circuit (IC) for controlling the pulsewidth modulation (PWM) inverters used in power conditioning systems for AC-voltage regulation. We also propose a multiple-loop control scheme for this PWM inverter control IC to achieve sinusoidal voltage regulation under large load variations. The control scheme is simple in architecture and thus facilitates realization

  13. Clustering-Based Simultaneous Task and Voltage Scheduling for NoC Systems 

    E-print Network

    Yang, Yu

    2011-08-08

    not only assigns voltage levels and starting time to each task (or Processing Element) but also naturally finds voltage-frequency clusters. Compared to a recent previous work, which performs task scheduling and voltage assignment sequentially, our method...

  14. Spontaneous voltage oscillations and response dynamics of a Hodgkin-Huxley type model of sensory hair cells

    PubMed Central

    2011-01-01

    We employ a Hodgkin-Huxley-type model of basolateral ionic currents in bullfrog saccular hair cells for studying the genesis of spontaneous voltage oscillations and their role in shaping the response of the hair cell to external mechanical stimuli. Consistent with recent experimental reports, we find that the spontaneous dynamics of the model can be categorized using conductance parameters of calcium-activated potassium, inward rectifier potassium, and mechano-electrical transduction (MET) ionic currents. The model is demonstrated for exhibiting a broad spectrum of autonomous rhythmic activity, including periodic and quasi-periodic oscillations with two independent frequencies as well as various regular and chaotic bursting patterns. Complex patterns of spontaneous oscillations in the model emerge at small values of the conductance of Ca2+-activated potassium currents. These patterns are significantly affected by thermal fluctuations of the MET current. We show that self-sustained regular voltage oscillations lead to enhanced and sharply tuned sensitivity of the hair cell to weak mechanical periodic stimuli. While regimes of chaotic oscillations are argued to result in poor tuning to sinusoidal driving, chaotically oscillating cells do provide a high sensitivity to low-frequency variations of external stimuli. PMID:22282726

  15. A Novel Flexible Sinusoidal Probe for Chronic Extracellular Brain Recording

    E-print Network

    Sohal, Harbaljit S; Jackson, Andrew; Baker, Stuart N; O'Neill, Anthony

    2015-01-01

    Current microelectrodes designed to record chronic neural activity suffer from recording instabilities due to the modulus mismatch between the electrode materials and the brain. We sought to address this by microfabricating a novel flexible neural probe. Our probe was fabricated from parylene-C with a WTi metal, using contact photolithography and reactive ion etching, with three design features to address this modulus mismatch: a sinusoidal shaft, a rounded tip and a polyimide anchoring ball. The anchor restricts movement of the electrode recording sites and the shaft accommodates the brain motion. We successfully patterned thick metal and parylene-C layers, with a reliable device release process leading to high functional yield and were able to sample stable neural activity for over 2 years with this probe. We have successfully optimized the fabrication process to produce a reliable probe with high functional yield. This novel reliably microfabricated probe can record stable neural activity for up to two yea...

  16. Reversible sinusoidal obstruction syndrome associated with tacrolimus following liver transplantation.

    PubMed

    Shen, Tian; Feng, Xiao-Wen; Geng, Lei; Zheng, Shu-Sen

    2015-05-28

    Sinusoidal obstruction syndrome (SOS), previously known as hepatic veno-occlusive disease, is a rare disorder in solid organ transplant patients, and is an uncommon complication after liver transplantation. Severe SOS with hepatic failure causes considerable mortality. Tacrolimus has been reported to be an offending agent, which potentially plays a role in the pathophysiological process of SOS. SOS due to tacrolimus has been reported in lung and pancreatic transplantations, but has never been described in a liver transplant recipient. Herein, we present a case of SOS after liver transplantation, which was possibly related to tacrolimus. A 27-year-old man developed typical symptoms of SOS with painful hepatomegaly, ascites and jaundice after liver transplantation, which regressed following withdrawal of tacrolimus. By excluding other possible predisposing factors, we concluded that tacrolimus was the most likely cause of SOS. PMID:26034381

  17. Reversible sinusoidal obstruction syndrome associated with tacrolimus following liver transplantation

    PubMed Central

    Shen, Tian; Feng, Xiao-Wen; Geng, Lei; Zheng, Shu-Sen

    2015-01-01

    Sinusoidal obstruction syndrome (SOS), previously known as hepatic veno-occlusive disease, is a rare disorder in solid organ transplant patients, and is an uncommon complication after liver transplantation. Severe SOS with hepatic failure causes considerable mortality. Tacrolimus has been reported to be an offending agent, which potentially plays a role in the pathophysiological process of SOS. SOS due to tacrolimus has been reported in lung and pancreatic transplantations, but has never been described in a liver transplant recipient. Herein, we present a case of SOS after liver transplantation, which was possibly related to tacrolimus. A 27-year-old man developed typical symptoms of SOS with painful hepatomegaly, ascites and jaundice after liver transplantation, which regressed following withdrawal of tacrolimus. By excluding other possible predisposing factors, we concluded that tacrolimus was the most likely cause of SOS. PMID:26034381

  18. Voltage Effects on a Commercial Plasma Globe

    NASA Astrophysics Data System (ADS)

    Simmons, G. G.; Saucedo, L.; Burin, M. J.; Nagy, A.; Zweben, S. J.

    2013-10-01

    Filamentary structures have been observed in both atmospheric and industrial dielectric barrier discharges, yet various physical aspects of filament formation remain unclear. An example of filament formation can be found in commercial plasma globes. These globes typically contain Neon/Xenon at a pressure near 740 Torr, and are supplied with high voltage (5-10kV) near 25 kHz. The reason why these conditions are optimal for filamentary structures is unknown. This work analyzes the effects of voltage amplitude and frequency on a plasma globe using a programmable high voltage supply. We find that increasing voltage amplitude generally increases the drawn current and the number of filaments, but does not significantly affect filament structure. Changing the AC voltage frequency on the other hand significantly affects filament structure, with higher frequencies generally resulting in more focused (smaller average diameter) filaments. These trends are discussed along with their physics and possible applications. Filamentary structures have been observed in both atmospheric and industrial dielectric barrier discharges, yet various physical aspects of filament formation remain unclear. An example of filament formation can be found in commercial plasma globes. These globes typically contain Neon/Xenon at a pressure near 740 Torr, and are supplied with high voltage (5-10kV) near 25 kHz. The reason why these conditions are optimal for filamentary structures is unknown. This work analyzes the effects of voltage amplitude and frequency on a plasma globe using a programmable high voltage supply. We find that increasing voltage amplitude generally increases the drawn current and the number of filaments, but does not significantly affect filament structure. Changing the AC voltage frequency on the other hand significantly affects filament structure, with higher frequencies generally resulting in more focused (smaller average diameter) filaments. These trends are discussed along with their physics and possible applications. Research supported by the U.S. DOE (DE-SC0006876) and the MARC grant (GM-08807).

  19. Predicting lateralization performance at high frequencies from auditory-nerve spike timing

    E-print Network

    Dreyer, Anna Alexandra

    2005-01-01

    Psychophysical sensitivity to interaural time differences (ITD) in the envelope of high- frequency sinusoidally amplitude-modulated (SAM) tones is generally poorer than that to low- frequency pure tones (PT). ITD sensitivity ...

  20. Sinusoidal obstruction syndrome (hepatic veno-occlusive disease).

    PubMed

    Fan, Cathy Q; Crawford, James M

    2014-12-01

    Hepatic sinusoidal obstruction syndrome (SOS) is an obliterative venulitis of the terminal hepatic venules, which in its more severe forms imparts a high risk of mortality. SOS, also known as veno-occlusive disease (VOD), occurs as a result of cytoreductive therapy prior to hematopoietic stem cell transplantation (HSCT), following oxaliplatin-containing adjuvant or neoadjuvant chemotherapy for colorectal carcinoma metastatic to the liver and treated by partial hepatectomy, in patients taking pyrrolizidine alkaloid-containing herbal remedies, and in other particular settings such as the autosomal recessive condition of veno-occlusive disease with immunodeficiency (VODI). A central pathogenic event is toxic destruction of hepatic sinusoidal endothelial cells (SEC), with sloughing and downstream occlusion of terminal hepatic venules. Contributing factors are SEC glutathione depletion, nitric oxide depletion, increased intrahepatic expression of matrix metalloproteinases and vascular endothelial growth factor (VEGF), and activation of clotting factors. The clinical presentation of SOS includes jaundice, development of right upper-quadrant pain and tender hepatomegaly, ascites, and unexplained weight gain. Owing to the potentially critical condition of these patients, transjugular biopsy may be the preferred route for liver biopsy to exclude other potential causes of liver dysfunction and to establish a diagnosis of SOS. Treatment includes rigorous fluid management so as to avoid excessive fluid overload while avoiding too rapid diuresis or pericentesis, potential use of pharmaceutics such as defibrotide, coagulolytic agents, or methylprednisolone, and liver transplantation. Proposed strategies for prevention and prophylaxis include reduced-intensity conditioning radiation for HSCT, treatment with ursodeoxycholic acid, and inclusion of bevacizumab with oxaliplatin-based chemotherapeutic regimes. While significant progress has been made in understanding the pathogenesis of SOS and in mitigating against its adverse outcomes, this condition remains a serious complication of a selective group of medical treatments. PMID:25755580

  1. High Voltage Lines: Hazard at a Distance.

    ERIC Educational Resources Information Center

    Marino, Andrew A.; Becker, Robert O.

    1978-01-01

    It appears that a variety of biological organisms, including man, are sensitive to both long and short-term exposure to the extra low frequency electric and magnetic fields produced by high voltage lines. (BB)

  2. Maximum group velocity in a one-dimensional model with a sinusoidally varying staggered potential

    NASA Astrophysics Data System (ADS)

    Nag, Tanay; Sen, Diptiman; Dutta, Amit

    2015-06-01

    We use Floquet theory to study the maximum value of the stroboscopic group velocity in a one-dimensional tight-binding model subjected to an on-site staggered potential varying sinusoidally in time. The results obtained by numerically diagonalizing the Floquet operator are analyzed using a variety of analytical schemes. In the low-frequency limit we use adiabatic theory, while in the high-frequency limit the Magnus expansion of the Floquet Hamiltonian turns out to be appropriate. When the magnitude of the staggered potential is much greater or much less than the hopping, we use degenerate Floquet perturbation theory; we find that dynamical localization occurs in the former case when the maximum group velocity vanishes. Finally, starting from an "engineered" initial state where the particles (taken to be hard-core bosons) are localized in one part of the chain, we demonstrate that the existence of a maximum stroboscopic group velocity manifests in a light-cone-like spreading of the particles in real space.

  3. Comparison of high temperature, high frequency core loss and dynamic B-H loops of a 2V-49Fe-49Co and a grain oriented 3Si-Fe alloy

    NASA Technical Reports Server (NTRS)

    Wieserman, W. R.; Schwarze, G. E.; Niedra, J. M.

    1992-01-01

    The design of power magnetic components such as transformers, inductors, motors, and generators, requires specific knowledge about the magnetic and electrical characteristics of the magnetic materials used in these components. Limited experimental data exists that characterizes the performance of soft magnetic materials for the combined conditions of high temperature and high frequency over a wide flux density range. An experimental investigation of a 2V-49-Fe-49Co (Supermendur) and a grain oriented 3 Si-Fe (Magnesil) alloy was conducted over the temperature range of 23 to 300 C and frequency range of 0.1 to 10 kHz. The effects of temperature, frequency, and maximum flux density on the core loss and dynamic B-H loops for sinusoidal voltage excitation conditions are examined for each of these materials. A comparison of the core loss of these two materials is also made over the temperature and frequency range investigated.

  4. Phase-shift estimation in sinusoidally illuminated images for lateral superresolution

    E-print Network

    Fienup, James R.

    Phase-shift estimation in sinusoidally illuminated images for lateral superresolution Sapna A illumination has been used to obtain lateral superresolution and axial sectioning in images. In both of these techniques multiple images are taken with the object illuminated by a sinusoidal pat- tern, the phase

  5. Independent control of reflex and volitional EMG modulation during sinusoidal pursuit tracking in humans

    Microsoft Academic Search

    M. T. V. Johnson; A. N. Kipnis; M. C. Lee; T. J. Ebner

    1993-01-01

    It is well known that during volitional sinusoidal tracking the long-latency reflex modulates in parallel with the volitional EMG activity. In this study, a series of experiments are reported demonstrating several conditions in which an uncoupling of reflex from volitional activity occurs. The paradigm consists of a visually guided task in which the subject tracked a sinusoid with the wrist.

  6. Sinusoidal pattern together with signs of moderate fetal hypoxia associated with a true knot of cord.

    PubMed

    Goldstein, I; Timor-Tritsch, I E; Zaidise, I; Divon, M; Paldi, E

    1981-02-01

    The fetal heart rate pattern of a dying fetus due to tightening of a true knot of cord is presented. Sinusoidal pattern was electronically recorded along wih bradycardia--tachycardia. The importance of the sinusoidal pattern is discussed. It seems to imply fetal compromise if observed together with other signs of moderate fetal distress. PMID:7194813

  7. A Self-Learning Solution for Torque Ripple Reduction for Non-Sinusoidal Permanent Magnet

    E-print Network

    Paris-Sud XI, Université de

    1 A Self-Learning Solution for Torque Ripple Reduction for Non-Sinusoidal Permanent Magnet Motor in a permanent-magnet non-sinusoidal synchronous motor. Solutions for calculating optimal currents are deduced are shown to confirm the validity of the proposed neural approach. Index Terms--Permanent Magnet Synchronous

  8. Physics 5B Winter 2009 Rate of Energy Transfer by Sinusoidal Waves on a String

    E-print Network

    California at Santa Cruz, University of

    Physics 5B Winter 2009 Rate of Energy Transfer by Sinusoidal Waves on a String Consider a sinusoidal wave traveling along the x­axis on a stretched string. Focus on the in­ finitesimal segment the kinetic energy and the potential energy of this string segment due to the passage of a traveling wave

  9. Physics 5B Winter 2009 Rate of Energy Transfer by Sinusoidal Waves on a String

    E-print Network

    California at Santa Cruz, University of

    Physics 5B Winter 2009 Rate of Energy Transfer by Sinusoidal Waves on a String Consider a sinusoidal wave traveling along the x-axis on a stretched string. Focus on the in- finitesimal segment the kinetic energy and the potential energy of this string segment due to the passage of a traveling wave

  10. Tomographic Characterization of Aquifer Heterogeneity with a Sinusoidal Signal

    NASA Astrophysics Data System (ADS)

    Lyle, S. A.; McElwee, C. D.

    2011-12-01

    We have been doing experimental field work using oscillatory pressure waves to investigate the hydraulic conductivity distribution between source and receiver wells. The Darcy's Law proportionality constant, hydraulic conductivity, describes the relative ease or rate at which water can move through a permeable medium and its fine-scale heterogeneity determines preferential flow rates and pathways. Traditional aquifer tests, such as slug and pumping tests, predict bulk hydraulic conductivity values without detailed information about aquifer heterogeneity. The multiple source and receiver signals of a hydraulic tomography aquifer test can estimate interwell heterogeneity, but it requires extensive time to collect and then invert large amounts of tomographic data. We have been using an innovative adaptation of a continuous oscillatory pressure signal to reduce the data collection and processing time associated with a tomography test. The amplitude and phase shift of the sinusoidal pressure signal are related to the hydraulic conductivity. Theory for a homogeneous aquifer predicts that the amplitude should decay exponentially with radial distance and the phase shift should increase linearly with radial distance. Both the exponential decay coefficient and the phase shift should vary inversely with the square root of the hydraulic conductivity. Extension of this simple theory to heterogeneous aquifer systems suggests the hydraulic conductivity should be replaced with a spatially averaged value. Multiple offset gathers (MOG) of ray paths were collected between tomographic well pairs for a given source location. Previous work used air pressure to oscillate the water column in the well. The present work introduces a sinusoidally pumped source regulated by a computer interface. Ray paths were modeled with a spatially weighted straight ray approximation method and analyzed with data processing programs that extend the 3D homogenous spherical radial equation to the heterogeneous case. A numerical model was used to check the heterogeneous extension for accuracy. High quality zero-offset profile ray paths (ZOP) were used to determine hydraulic conductivity, K, at a relatively fine scale and interpreted into representative aquifer models between different tomographic well pairs. The aquifer models were used with MOG data to evaluate the anisotropy ratio and lateral heterogeneity of the aquifer. Two different oscillatory periods, 3 and 30-sec, were evaluated and compared to previous work at the site. Analysis indicates that the 3-sec period data were more sensitive to the anisotropy ratio and both periods are capable of resolving K zones of about 3 feet or 1 meter. In summary, the use of oscillatory pressure waves for hydraulic tomographic reconstruction of hydraulic conductivity distributions looks promising. This work was funded in part by the Strategic Environmental Research and Development Program (SERDP) as project ER-1367.

  11. Experimental validation of a high voltage pulse measurement method.

    SciTech Connect

    Cular, Stefan; Patel, Nishant Bhupendra; Branch, Darren W.

    2013-09-01

    This report describes X-cut lithium niobate's (LiNbO3) utilization for voltage sensing by monitoring the acoustic wave propagation changes through LiNbO3 resulting from applied voltage. Direct current (DC), alternating current (AC) and pulsed voltage signals were applied to the crystal. Voltage induced shift in acoustic wave propagation time scaled quadratically for DC and AC voltages and linearly for pulsed voltages. The measured values ranged from 10 - 273 ps and 189 ps - 2 ns for DC and non-DC voltages, respectively. Data suggests LiNbO3 has a frequency sensitive response to voltage. If voltage source error is eliminated through physical modeling from the uncertainty budget, the sensor's U95 estimated combined uncertainty could decrease to ~0.025% for DC, AC, and pulsed voltage measurements.

  12. Enhanced CD34 expression of sinusoid-like vascular endothelial cells in hepatocellular carcinoma.

    PubMed

    Cui, S; Hano, H; Sakata, A; Harada, T; Liu, T; Takai, S; Ushigome, S

    1996-10-01

    The immunohistochemical expression of CD34 (human hematopoietic stem cell and endothelial cell marker) and laminin were studied in chronic liver diseases and hepatocellular carcinoma (HCC) to elucidate whether their expression reflected phenotypic differences between non-cancerous sinusoids and sinusoid-like tumor vessels. In normal liver, hepatic sinusoids were always negative for CD34 and laminin. In chronic hepatitis and cirrhosis, the two antigens were sparsely expressed in capillarized sinusoids at periportal and perinodular area. In advanced HCC, CD34 was strongly and diffusely expressed by the endothelial lining of sinusoid-like tumor vessels. However, early-stage HCC showed a wide spectrum of CD34 expression from negative to focal and diffuse, strongly positive staining in sinusoid-like vessels. Laminin was strongly expressed in advanced HCC but not in early-stage HCC. The results indicate that the enhanced expression of CD34 by sinusoidal endothelial cells may reflect the phenotypic change of endothelial cells in chronic liver diseases and HCC, and that the expression may correlate with the processes of angiogenesis induced by hepatocarcinogenesis. PMID:8916144

  13. Human smooth pursuit tracking eye movement analysis in the frequency domain 

    E-print Network

    Sa, Zhijun

    1995-01-01

    Human smooth pursuit tracking eye movements were analyzed in the frequency domain. The stimulus used was a sum of sinusoids, in lieu of white Gaussian noise. The feasibility of the nonlinear analysis by a sum of sinusoids consisting of only 6...

  14. Voluntary ocular tracking movements in response to a sinusoidally moving intermittently active sound source.

    PubMed

    Fiebig, E; Schaefer, K P; Süss, K J

    1982-01-01

    Voluntary eye movements in response to a sinusoidally moving, intermittently active sound source were investigated in 40 young healthy human subjects. Visual afferent input was prevented during the experiments. With increasing burst repetition rates of the sound source, different forms of eye movements were observed: a) so-called single and repetitive adversive movements consisting of saccades which occur with certain latencies in response to single bursts; b) so-called saccadic eye tracking movements which are characterized by numerous small saccades occurring in accordance with the target (sound source) movement but lacking a time correlation between the saccades and single bursts. It was found that saccadic eye tracking movements were performed instead of adversive movements when at least 4 to 10 bursts per movement period of the sound source was transmitted (with movement frequencies of the sound source from 0.1 to 0.5 Hz). Slight intersaccadic drifts, which could be regularly observed in all types of eye movements were interpreted as instability of fixation in darkness. PMID:7185788

  15. Use of a sinusoidal current of optimal frequency to stimulate skin wound healing

    Microsoft Academic Search

    A. V. Nikolaev; A. B. Shekhter; L. A. Mamedov; A. P. Novikov; N. K. Manucharov

    1984-01-01

    UDC 616.5-001.4-003.93-02:615.874 METHOD Experiments (10 series) were carried out on 120 noninbred male albino rats weighing about 200 g, under general anesthesia. The experimental model in series I-VIII consisted of linear incised skin wounds 5 cm long, inflicted on the dorsum of the rats and closed with three interrupted sutures, whereas in series IX-X, full~ thickness excised wounds 400 mm

  16. The corrosion of Cu-Ni alloy in a chloride solution subjected to periodic voltage modulation: Part II

    Microsoft Academic Search

    Shashi B. Lalvani; Jaw-Ching Kang; Nenand V. Mandich

    1998-01-01

    The corrosion of samples of CDA 706 copper-nickel alloy due to the superimposition of alternating voltages was found to occur via intergranular corrosion and cracking mechanisms, as evidenced by scanning electron microscopy. Experiments were conducted at three different DC potentials on which sinusoidal full-wave, positive half-wave rectified and negative half-wave voltages were superimposed under nitrogen or air purge. Evidence of

  17. Car-Parrinello Molecular Dynamics With A Sinusoidal Time-Dependent Potential Field

    E-print Network

    Alznauer, Tobias

    2012-01-01

    A sinusoidal external field is applied in Car-Parrinello molecular dynamics simulations. We present an implementation and discuss first test applications to electron and ion transfers in complex molecular systems.

  18. Smooth local sinusoidal bases on two-dimensional L-shaped regions

    Microsoft Academic Search

    Xiang-Gen Xia

    1998-01-01

    In this article, we construct two-dimensional continuous\\/smooth local sinusoidal bases (also called Malvar wavelets) defined\\u000a onL-shaped regions. With this construction, one is able to construct local sinusoidal bases and lapped orthogonal transforms\\u000a (LOT) on arbitrarily shaped regions. This work is motivated from and useful in object-based video coding, where a segmented\\u000a moving object may have arbitrary shape and block transform

  19. Design of error-compensating algorithms for sinusoidal phase shifting interferometry

    SciTech Connect

    Groot, Peter de

    2009-12-10

    An improved approach to interferometry using sinusoidal phase shifting balances several harmonic components in the interference signal against each other. The resulting computationally efficient phase-estimation algorithms have low sensitivity to errors such as spurious intensity noise, vibration, and errors in the phase shift pattern. Specific example algorithms employing 8 and 12 camera frames illustrate design principles that are extendable to algorithms of any length for applications that would benefit from a simplified, sinusoidal phase shift.

  20. Sinusoidal heart rate pattern and fetal distress secondary to severe anemia.

    PubMed

    Backes, C; Cordero, L; Warner, R; O'Shaughnessy, R

    1980-04-01

    A case of sinusoidal fetal heart rate (FHR) pattern with fetal anemia is described. The etiology of the pattern appears to have been fetal anemia from an umbilical cord knot, abruptio placentae and fetal asphyxia. The poor neonatal outcome in our case and a review of the literature suggest that a sinusoidal pattern is an ominous sign demanding complete evaluation of fetal well-being and often prompt obstetric intervention. The use of scalp capillary hematocrit is suggested. PMID:7373600

  1. Measurement of a cross-sectional profile of a thread gauge using a sinusoidally vibrating interference pattern

    SciTech Connect

    Li Jinhuan; Sasaki, Osami

    2011-07-10

    A sinusoidally vibrating interference pattern (SVIP) is used as an exact spatial scale in order to measure a cross-sectional profile of a thread gauge. The SVIP is projected on the thread gauge surface, and lights diffracted and reflected from the end points of the thread gauge surface are extracted by spatial frequency filtering in an imaging system to make an image of the end points whose positions are decided by the peak positions of amplitude distributions in the image. The coordinates of the end points or the cross-sectional profile of the thread gauge is obtained from the phases measured at the positions of the end points, phase distribution of the SVIP on a CCD image sensor, and the pixel positions of the CCD image sensor.

  2. The hepatic sinusoid 'classic and contemporary’: a report on the 17th international symposium on cells of the hepatic sinusoid (ISCHS)

    PubMed Central

    2014-01-01

    The 17th ISCHS took place in Osaka, Japan, on 23 to 25 September 2013. This symposium focuses on an exchange of views on the structure and function of hepatic sinusoidal cells in addition to their roles in clinical pathophysiology. PMID:24484528

  3. A new technique of frequency synthesis

    Microsoft Academic Search

    W. Zhou

    1993-01-01

    A novel method for the design of a frequency synthesizer is described. It is based on precision frequency measurement techniques. The frequency synthesis can be accomplished by measuring the synthesized frequency signal, comparing it with the desired frequency, and time (pulse width) - voltage transformation. In this synthesizer there are no frequency multipliers, mixers, or any other frequency transformation circuits

  4. Graded boosting of synaptic signals by low-threshold voltage-activated calcium conductance.

    PubMed

    Carbó Tano, Martín; Vilarchao, María Eugenia; Szczupak, Lidia

    2015-07-01

    Low-threshold voltage-activated calcium conductances (LT-VACCs) play a substantial role in shaping the electrophysiological attributes of neurites. We have investigated how these conductances affect synaptic integration in a premotor nonspiking (NS) neuron of the leech nervous system. These cells exhibit an extensive neuritic tree, do not fire Na(+)-dependent spikes, but express an LT-VACC that was sensitive to 250 ?M Ni(2+) and 100 ?M NNC 55-0396 (NNC). NS neurons responded to excitation of mechanosensory pressure neurons with depolarizing responses for which amplitude was a linear function of the presynaptic firing frequency. NNC decreased these synaptic responses and abolished the concomitant widespread Ca(2+) signals. Coherent with the interpretation that the LT-VACC amplified signals at the postsynaptic level, this conductance also amplified the responses of NS neurons to direct injection of sinusoidal current. Synaptic amplification thus is achieved via a positive feedback in which depolarizing signals activate an LT-VACC that, in turn, boosts these signals. The wide distribution of LT-VACC could support the active propagation of depolarizing signals, turning the complex NS neuritic tree into a relatively compact electrical compartment. PMID:25972583

  5. Mixed voltage VLSI design

    NASA Technical Reports Server (NTRS)

    Panwar, Ramesh; Rennels, David; Alkalaj, Leon

    1993-01-01

    A technique for minimizing the power dissipated in a Very Large Scale Integration (VLSI) chip by lowering the operating voltage without any significant penalty in the chip throughput even though low voltage operation results in slower circuits. Since the overall throughput of a VLSI chip depends on the speed of the critical path(s) in the chip, it may be possible to sustain the throughput rates attained at higher voltages by operating the circuits in the critical path(s) with a high voltage while operating the other circuits with a lower voltage to minimize the power dissipation. The interface between the gates which operate at different voltages is crucial for low power dissipation since the interface may possibly have high static current dissipation thus negating the gains of the low voltage operation. The design of a voltage level translator which does the interface between the low voltage and high voltage circuits without any significant static dissipation is presented. Then, the results of the mixed voltage design using a greedy algorithm on three chips for various operating voltages are presented.

  6. Nonlinear electrokinetics at large voltages

    NASA Astrophysics Data System (ADS)

    Bazant, Martin Z.; Sabri Kilic, Mustafa; Storey, Brian D.; Ajdari, Armand

    2009-07-01

    The classical theory of electrokinetic phenomena assumes a dilute solution of point-like ions in chemical equilibrium with a surface whose double-layer voltage is of order the thermal voltage, kBT/e=25 mV. In nonlinear 'induced-charge' electrokinetic phenomena, such as ac electro-osmosis, several volts ?100kBT/e are applied to the double layer, and the theory breaks down and cannot explain many observed features. We argue that, under such a large voltage, counterions 'condense' near the surface, even for dilute bulk solutions. Based on simple models, we predict that the double-layer capacitance decreases and the electro-osmotic mobility saturates at large voltages, due to steric repulsion and increased viscosity of the condensed layer, respectively. The former suffices to explain observed high-frequency flow reversal in ac electro-osmosis; the latter leads to a salt concentration dependence of induced-charge flows comparable to experiments, although a complete theory is still lacking.

  7. Estimating a sinusoid in low SNR coloured noise

    Microsoft Academic Search

    Barry G. Quinn

    2004-01-01

    We propose a procedure for locating a spectral line, when the signal to noise ratio is so small that the line is obscured in the periodogram (power spectrum) by the coloured background noise. The procedure can be totally automated, and most, if not all, of the computations can be done in the frequency domain.

  8. Microwave integrated circuit for Josephson voltage standards

    NASA Technical Reports Server (NTRS)

    Holdeman, L. B.; Toots, J.; Chang, C. C. (inventors)

    1980-01-01

    A microwave integrated circuit comprised of one or more Josephson junctions and short sections of microstrip or stripline transmission line is fabricated from thin layers of superconducting metal on a dielectric substrate. The short sections of transmission are combined to form the elements of the circuit and particularly, two microwave resonators. The Josephson junctions are located between the resonators and the impedance of the Josephson junctions forms part of the circuitry that couples the two resonators. The microwave integrated circuit has an application in Josephson voltage standards. In this application, the device is asymmetrically driven at a selected frequency (approximately equal to the resonance frequency of the resonators), and a d.c. bias is applied to the junction. By observing the current voltage characteristic of the junction, a precise voltage, proportional to the frequency of the microwave drive signal, is obtained.

  9. High-Frequency Resonant Transistor DC-DC Converters

    Microsoft Academic Search

    Robert L. Steigerwald

    1984-01-01

    Transistor dc-dc converters which employ a resonant circuit are described. A resonant circuit is driven with square waves of current or voltage, and by adjusting the frequency around the resonant point, the voltage on the resonant components can be adjusted to any practical voltage level. By rectifying the voltage across the resonant elements, a dc voltage is obtained which can

  10. Control Strategy of a Parallel System Using Both Matrix Converter and Voltage Type Inverter

    NASA Astrophysics Data System (ADS)

    Itoh, Jun-Ichi; Tamura, Hiroshi

    This paper proposes a control strategy for a matrix converter and voltage type inverter in a parallel system that does not require of interconnection reactors. The proposed control strategy is to divide the operation time between a matrix converter and a voltage type inverter. The operation time of each converter is divided in every carrier cycle. As a result, interconnection reactors are not required and the sinusoidal input current waveform of a matrix converter can be obtained. The total output voltage of the proposed system and the output power division ratio for a matrix converter and a voltage type inverter are controlled by the time division ratio of each converter. Furthermore, the voltage error resulting from the operation of time division control was analyzed and compensated. The availability of the proposed system and the validity of the proposed control method are confirmed by experimental results.

  11. Voltage sag detection based on rectified voltage processing

    Microsoft Academic Search

    Andrea Florio; Andrea Mariscotti; Maurizio Mazzucchelli

    2004-01-01

    An algorithm for voltage sag detection based on rectified voltage processing is presented and its performances are evaluated by means of simulated and real voltage waveforms (recorded at some low-voltage busbars and measured on a scaled prototype of a voltage support system). The algorithm is intended to detect voltage sag occurrence and to trigger the disconnection of the faulty supply

  12. 1.5 GHz single-photon detection at telecommunication wavelengths using sinusoidally gated InGaAs/InP avalanche photodiode.

    PubMed

    Namekata, Naoto; Adachi, Shunsuke; Inoue, Shuichiro

    2009-04-13

    We report a telecom-band single-photon detector for gigahertz clocked quantum key distribution systems. The single-photon detector is based on a sinusoidally gated InGaAs/InP avalanche photodiode. The gate repetition frequency of the single-photon detector reached 1.5 GHz. A quantum efficiency of 10.8 % at 1550 nm was obtained with a dark count probability per gate of 6.3 x 10(-7) and an afterpulsing probability of 2.8 %. Moreover, the maximum detection rate of the detector is 20 MHz. PMID:19365453

  13. A periodic voltage modulation effect on the corrosion oF Cu-Ni Alloy

    Microsoft Academic Search

    Wei Wei Qiu; M. Pagano; G. Zhang; S. B. Lalvani

    1995-01-01

    It is suggested in the literature that the application of A.C. fields results in enhanced corrosion rates of materials while the mechanism of corrosion is changed. In this study, corrosion caused by sinusoidal alternating voltage (A.V.) fields in Cu-10Ni alloy (CDA706) in simulated seawater is investigated by: (i) immersion tests and (ii) characterization of corrosion products. The experimental data show

  14. Capacitor Voltage Control in a Cascaded Multilevel Inverter as a Static Var Generator

    Microsoft Academic Search

    M. Li; J. N. Chiasson; L. M. Tolbert

    2006-01-01

    The widespread use of non-linear loads and power electronics converters has increased the generation of non-sinusoidal and non-periodic currents and voltages in power systems. Reactive power compensation or control is an important part of a power system to minimize power transmission losses. Given a modulation index, the switch times can be chosen to achieve the fundamental while eliminating specific harmonics.

  15. Electron heating in capacitively coupled plasmas revisited: single and multi-frequency discharges

    NASA Astrophysics Data System (ADS)

    Lafleur, Trevor

    2013-09-01

    Using particle-in-cell (PIC) simulations, we re-analyse the mechanism of electron heating in low pressure capacitively coupled plasmas (CCPs). After equilibrium has been reached in the simulations, spatio-temporal moments of the electron distribution function are taken within the rf cycle, and from this the density, current, pressure, and momentum loss due to collisions, of the electrons is found in the discharge. With these moments we then reconstruct each term in the electron fluid mechanical energy conservation equation, so as to explicitly analyse the power deposition process. We perform simulations for both single frequency sinusoidal discharges, and also for more recent multi-frequency, or ``tailored voltage waveform'' driven discharges. The single frequency (13.56 MHz) simulations are modelled on the original experiments in Argon performed by Godyak, showing the transition from a bi-Maxwellian distribution function at low pressure (below 200 mTorr) to a Druyvestyen-type distribution at high pressures (above 400 mTorr). The results of the PIC moment analysis shows that only two terms in the fluid conservation equation contribute a net power deposition: a term accounting for collisional power absorption, and a term accounting for pressure heating. The latter term is dominant at low pressures, while the former is dominant at higher pressures. We find however that the collisional heating is almost always significant, and even at the lowest pressure, accounts for about 40% of the total power absorption. By comparing the electron momentum loss due to collisions with that usually used in analytical sheath models, we find a significant difference at low pressures, which cannot be explained by conventional local kinetic theories based on the two-term expansion of the Boltzmann equation. The moment analysis is repeated for the multi-frequency discharges, where we obtain similar results: collisional power absorption is always observed to be significant, even at the lowest pressures simulated (20 mTorr). However the generation of a bias voltage due to the electrical asymmetry effect, and consequently the unequal division of the sheath voltages, causes high frequency oscillations to develop in the plasma at frequencies more than an order of magnitude higher than the applied rf frequencies. These so-called nonlinear plasma series resonance oscillations are found to enhance both the collisional and pressure heating, and for sufficiently large applied voltages, an additional heating mechanism is identified associated with the electron inertial terms in the conservation equation.

  16. Large endolymphatic potentials from low-frequency and infrasonic tones in the guinea pig.

    PubMed

    Salt, Alec N; Lichtenhan, Jeffery T; Gill, Ruth M; Hartsock, Jared J

    2013-03-01

    Responses of the ear to low-frequency and infrasonic sounds have not been extensively studied. Understanding how the ear responds to low frequencies is increasingly important as environmental infrasounds are becoming more pervasive from sources such as wind turbines. This study shows endolymphatic potentials in the third cochlear turn from acoustic infrasound (5?Hz) are larger than from tones in the audible range (e.g., 50 and 500?Hz), in some cases with peak-to-peak amplitude greater than 20?mV. These large potentials were suppressed by higher-frequency tones and were rapidly abolished by perilymphatic injection of KCl at the cochlear apex, demonstrating their third-turn origins. Endolymphatic iso-potentials from 5 to 500?Hz were enhanced relative to perilymphatic potentials as frequency was lowered. Probe and infrasonic bias tones were used to study the origin of the enhanced potentials. Potentials were best explained as a saturating response summed with a sinusoidal voltage (Vo), that was phase delayed by an average of 60° relative to the biasing effects of the infrasound. Vo is thought to arise indirectly from hair cell activity, such as from strial potential changes caused by sustained current changes through the hair cells in each half cycle of the infrasound. PMID:23464026

  17. The Integrity bare-metal stent made by continuous sinusoid technology.

    PubMed

    Turco, Mark A

    2011-05-01

    The Integrity Coronary Stent System (Medtronic Vascular, CA, USA) is a low-profile, open-cell, cobalt-chromium-alloy advanced bare-metal iteration of the well-known Driver/Micro-Driver Coronary Stent System (Medtronic Vascular). The Integrity stent is made with a process called continuous sinusoid technology. This process allows stent construction via wrapping a single thin strand of wire around a mandrel in a sinusoid configuration, with laser fusion of adjacent crowns. The wire-forming process and fusion pattern provide the stent with a continuous preferential bending plane, intended to allow easier access to, and smoother tracking within, distal and tortuous vessels while radial strength is maintained. Continuous sinusoid technology represents innovation in the design of stent platforms and will provide a future stent platform for newer technology, including drug-eluting stent platforms, drug-filled stents and core wire stents. PMID:21542702

  18. Frequency response of a photo-viscoelastic material

    Microsoft Academic Search

    G. W. Brown; D. R. Selway

    1964-01-01

    An electromagnetic shaker was used to apply sinusoidal axial displacements to one end of a column of Hysol 4364, an optically sensitive urethane rubber compound of low modulus. The nondriven end of the column was free. The column was excited at frequencies of 81, 244, 424, 603 and 783 cps, corresponding to the first five resonant frequencies of longitudinal vibration.

  19. Solution to the indexing problem of frequency domain simulation experiments

    Microsoft Academic Search

    Mousumi Mitra; Stephen K. Park

    1991-01-01

    A frequency domain simulation experiment is one in which selected system parameters are oscillated sinusoidally to induce oscillations in one or more system statistics of interest. A spectral (Fourier) analysis of these induced oscillations is then performed. To perform this spectral analysis, all oscillation frequencies must be referenced to a common, independent variable--an oscillation index. In a discrete-event simulation, the

  20. Voltage Converter TYPICAL APPLICATION

    E-print Network

    Berns, Hans-Gerd

    s Inverting and Doubling Modes s Minimum Open Circuit Voltage Conversion Efficiency: 99% s Typical Power Voltage RL = 1k Inverter, LV = Open q 3 5.5 V Inverter, LV = GND q 1.5 5.5 V Doubler, LV = VOUT q 2.5 5 % Voltage Conversion Efficiency No Load 99 99.96 % Oscillator Sink or Source Current Boost = Open ±1.1 µ

  1. Direct subnanosecond voltage monitors

    SciTech Connect

    Barth, J.E.; Sajeant, W.J.

    1981-01-01

    Advanced system development in the subnanosecond time frame increasingly demands high-resolution voltage measurements for both single-shot and repetitive operation. Voltage monitors having capabilities up to the hundred kilovolt level have been developed for direct measurements in discrete and transmission line geometries. Resolutions of 100 ps at 100 kV to 30 ps at 20 kV have been achieved. Detailed test data is presented and ultimate voltage scaling limits are discussed.

  2. High voltage RF feedthrough bushing

    DOEpatents

    Grotz, Glenn F. (Huntington Station, NY)

    1984-01-01

    Described is a multi-element, high voltage radio frequency bushing for trmitting RF energy to an antenna located in a vacuum container. The bushing includes a center conductor of complex geometrical shape, an outer coaxial shield conductor, and a thin-walled hollow truncated cone insulator disposed between central and outer conductors. The shape of the center conductor, which includes a reverse curvature portion formed of a radially inwardly directed shoulder and a convex portion, controls the uniformity of the axial surface gradient on the insulator cone. The outer shield has a first substantially cylindrical portion and a second radially inwardly extending truncated cone portion.

  3. F-TF.A, F-BF.A.3 Exploring Sinusoidal Functions

    NSDL National Science Digital Library

    This is a task from the Illustrative Mathematics website that is one part of a complete illustration of the standard to which it is aligned. Each task has at least one solution and some commentary that addresses important asects of the task and its potential use. Here are the first few lines of the commentary for this task: In this task we will explore the effect that changing the parameters in a sinusoidal function has on the graph of the function. A general sinusoidal fu...

  4. Changes in sinusoidal plasma membrane enzyme activities during the pre-replicative phase of liver regeneration.

    PubMed

    Enrich, C; Bachs, O; Soriano, M; Serratosa, J

    1986-10-01

    Changes in a range of plasma membrane enzyme activities during the early period of liver regeneration are thought to be related to the initiation of DNA synthesis and the triggering of cellular activation. The sinusoidal plasma membrane was isolated from control and partially hepatectomized animals at various intervals during the pre-replicative phase. The specific activities of 5'-nucleotidase, (Na+ + K+)-ATPase, Ca2+-ATPase, Mg2+-ATPase showed that after partial hepatectomy changes in the enzyme activities at the sinusoidal plasma membrane region occur. These changes are probably related to the remodeling of the cell-surface that occurs before the division of hepatocytes. PMID:3019405

  5. Basic study of transient breakdown voltage in solid dielectric cables

    SciTech Connect

    Not Available

    1982-02-01

    A comprehensive review of publications relating to cross linked polyethylene (XLPE) and ethylene propylene rubber (EPR) insulated cables revealed that there is very little known with respect to the life expectancy, the final factory voltage test background and the mechanism of voltage breakdown of these cables. In this study a new methodology was developed which depends on the investigation of breakdown voltages at various voltage transients such as unipolarity pulses and dual-polarity pulses, and ac voltage at power and high frequency. Also, a new approach to statistical testing was developed which allows one to establish a correlation among the breakdown voltages obtained with various voltage transients. Finally, a method for the determination of threshold voltage (true partial discharge inception voltage) regardless of the magnitude of apparent charge was developed. Extensive statistical testing of breakdown voltages was conducted using: impulses with front durations from approximately 1.5 to 1000 ..mu..s and times to half-values from 40 to 3000 ..mu..s; dual-polarity pulses consisting of dc voltage and standard impulse of opposite polarity; combined ac and dc voltages; and ac voltages at power and high frequencies. Based on the results of this testing, a model of breakdown and electrical aging of XLPE and EPR insulated cables was developed as well as life expectancy characteristics for high voltage stress XLPE insulated cables operated in a dry environment at room temperature and at 90/sup 0/C. Life expectancy characteristics for EPR insulated cables are approximated. A test procedure including requirements for full-reel factory voltage withstand and partial discharge testing of finished XLPE and EPR insulated cables is proposed. Cables that pass the proposed tests will exhibit a smaller rate of failure in service than cables tested in accordance with present practices.

  6. Dynamic voltage regulation and power export in a distribution system using distributed generation

    Microsoft Academic Search

    Aamir Hanif; Muhammad Ahmed Choudhry

    2009-01-01

    The major aim of power quality (PQ) enhancing techniques is to maintain a specified voltage magnitude at a desired frequency\\u000a for sensitive loads irrespective of faults on the power distribution network. The dynamic voltage restorer (DVR) is a device\\u000a used to mitigate voltage sags to regulate load voltage. This paper presents a mathematical model for leading series voltage\\u000a injection to

  7. Microprocessor-based true-RMS line voltage monitor

    SciTech Connect

    Silberberg, J.L.

    1981-08-01

    The Bureau of Radiological Health has developed a true-RMS line voltage monitor for use by Food and Drug Administration personnel in determining compliance with the performance standard for diagnostic x-ray equipment. The instrument measures ac voltage with less than +-0.1% error over a wide range of voltage and frequency. It is compact and lightweight and thus suitable for field use.

  8. Battery voltage regulation system

    Microsoft Academic Search

    N. Mayumi; H. Kato; H. Matsuhashi

    1986-01-01

    A battery voltage regulating system is described for an automotive vehicle having a battery, an alternator driven by an internal combustion engine mounted on the vehicle and generating an alternating current, and a full-wave rectifier for rectifying the alternating current to charge the battery. The system consists of: an operational amplifier connected to the battery for comparing a battery voltage

  9. Cascaded voltage collapse

    SciTech Connect

    Sekine, Y. (Tokyo Univ. (Japan)); Ohtsuki, H. (Kansai Electric Power Co., Inc., Osaka (Japan))

    1990-02-01

    The dynamic phenomena of voltage collapse are analyzed by the method of dynamic simulation using induction motor models. From the view point of dynamic phenomena, the voltage collapse starts locally at the weakest node and spreads out to the other weak nodes.

  10. Voltage verification unit

    DOEpatents

    Martin, Edward J. (Virginia Beach, VA)

    2008-01-15

    A voltage verification unit and method for determining the absence of potentially dangerous potentials within a power supply enclosure without Mode 2 work is disclosed. With this device and method, a qualified worker, following a relatively simple protocol that involves a function test (hot, cold, hot) of the voltage verification unit before Lock Out/Tag Out and, and once the Lock Out/Tag Out is completed, testing or "trying" by simply reading a display on the voltage verification unit can be accomplished without exposure of the operator to the interior of the voltage supply enclosure. According to a preferred embodiment, the voltage verification unit includes test leads to allow diagnostics with other meters, without the necessity of accessing potentially dangerous bus bars or the like.

  11. Hepatic sinusoidal cells in health and disease: update from the 14th International Symposium.

    PubMed

    Smedsrød, Bård; Le Couteur, David; Ikejima, Kenichi; Jaeschke, Hartmut; Kawada, Norifumi; Naito, Makoto; Knolle, Percy; Nagy, Laura; Senoo, Haruki; Vidal-Vanaclocha, Fernando; Yamaguchi, Noriko

    2009-04-01

    This review aims to give an update of the field of the hepatic sinusoid, supported by references to presentations given at the 14th International Symposium on Cells of the Hepatic Sinusoid (ISCHS2008), which was held in Tromsø, Norway, August 31-September 4, 2008. The subtitle of the symposium, 'Integrating basic and clinical hepatology', signified the inclusion of both basal and applied clinical results of importance in the field of liver sinusoidal physiology and pathophysiology. Of nearly 50 oral presentations, nine were invited tutorial lectures. The authors of the review have avoided writing a 'flat summary' of the presentations given at ISCHS2008, and instead focused on important novel information. The tutorial presentations have served as a particularly important basis in the preparation of this update. In this review, we have also included references to recent literature that may not have been covered by the ISCHS2008 programme. The sections of this review reflect the scientific programme of the symposium (http://www.ub.uit.no/munin/bitstream/10037/1654/1/book.pdf): 1. Liver sinusoidal endothelial cells. 2. Kupffer cells. 3. Hepatic stellate cells. 4. Immunology. 5. Tumor/metastasis. Symposium abstracts are referred to by a number preceded by the letter A. PMID:19210626

  12. Ultrafast 2D NMR Spectroscopy Using Sinusoidal Gradients: Principles and Ex Vivo Brain Investigations

    E-print Network

    Frydman, Lucio

    Ultrafast 2D NMR Spectroscopy Using Sinusoidal Gradients: Principles and Ex Vivo Brain ultrafast acquisitions of 2D NMR spectra with suitable spectral widths on a microimaging probe (for both Wiley-Liss, Inc. Key words: ultrafast 2D NMR; magnetic resonance spectros- copy; brain metabolites; 2D

  13. EFFECTS OF CONTINUOUS-WAVE, PULSED, AND SINUSOIDAL-AMPLITUDE-MODULATED MICROWAVES ON BRAIN ENERGY METABOLISM

    EPA Science Inventory

    A comparison of the effects of continuous wave, sinusoidal-amplitude modulated, and pulsed square-wave-modulated 591-MHz microwave exposures on brain energy metabolism was made in male Sprague Dawley rats (175-225g). Brain NADH fluorescence, adensine triphosphate (ATP) concentrat...

  14. OPTIMAL UNIFIED IIR ARCHITECTURES FOR TIME-RECURSIVE DISCRETE SINUSOIDAL TRANSFORMS

    E-print Network

    Liu, K. J. Ray

    . INTRODUCTION Discrete sinusoidal transforms play an important role in various digital signal processing applications, such as spectrum analysis, speech and image signal processing, computer tomography.1 Optimal Unified IIR Structures Input data arrive serially in most real-time signal processing applications

  15. Direct torque control of permanent magnet synchronous motors with non-sinusoidal back-EMF

    E-print Network

    Ozturk, Salih Baris

    2009-05-15

    torque control of permanent magnet synchronous motor (PMSM) with sinusoidal back-EMF is discussed in detail. Secondly, the proposed two-phase conduction mode for DTC of BLDC motors is introduced in the constant torque region. In this control scheme, only...

  16. Sinusoidal commutation of slotless permanent magnet synchronous machines using discrete Hall sensor feedback

    Microsoft Academic Search

    Todd D. Batzel; Kwang Y. Lee

    1999-01-01

    An implementation for sinusoidal current control of a slotless permanent magnet synchronous motor (PMSM) with discrete Hall sensor position feedback is presented. To estimate the rotor position of the slotless PMSM, a flux estimation technique is used that takes advantage of the slotless machine's characteristically low inductance to limit flux estimation error. The rotor position is estimated using a reference

  17. Some thoughts about the radiation of antennas excited by non-sinusoidal currents

    Microsoft Academic Search

    RAFAEL GÓMEZ MARTIN; JUAN A. MORENTE; BERNARDO G. OLMEDO

    1984-01-01

    In this paper, general expressions for the fields produced by an arbitrarily variable charge and current distribution are derived in the time domain. The results are compared with those obtained by Fourier analysis. Starting from these results, the non-sinusoidal fields produced by the basic large-current radiator when fed by different excitation currents, are analysed

  18. A Jitter-Robust High Data Rate Impulse Radio System with an Orthogonal Sinusoidal Correlation Receiver

    Microsoft Academic Search

    Han Huang; Huarui Yin; Guo Wei; Jinkang Zhu

    2005-01-01

    In this paper, the impulse radio (IR) system of pulse position amplitude modulation (PPAM) using an orthogonal sinusoidal correlation receiver (OSCR) is proposed. PPAM combines pulse position modulation (PPM) with pulse amplitude modulation (PAM) to provide higher data throughput with low computational complexity. But the performance of PPAM is considerably sensitive to timing jitter. OSCR has remarkable tolerance against timing

  19. Room-temperature multiwavelength erbium-doped fiber ring laser employing sinusoidal phase-modulation feedback

    Microsoft Academic Search

    Kejiang Zhou; Dongyun Zhou; Fengzhong Dong; Nam Quoc Ngo

    2003-01-01

    An effective method for achieving a room-temperature multiwavelength erbium-doped fiber ring laser is presented. Simultaneous multiwavelength lasing with 0.5-nm intervals is achieved both experimentally and theoretically by addition of sinusoidal phase modulation in the ring cavity to prevent single-wavelength oscillation.

  20. Jeremy McGibbon Page 1 Vertically Vibrated Ball-Chains in a Sinusoidal Potential

    E-print Network

    Morris, Stephen W.

    in their measurements (4mm to 10mm wavelength), while remaining within the constraint of a 14 inch diameter. Most/cm. Initially, the plate used was a square piece of plastic with sinusoidal ridges 4mm in wavelength and 1mm in depth, up to a 0.02 mm machining tolerance. Test runs were performed on this plate in order to determine

  1. Direct torque control of permanent magnet synchronous motors with non-sinusoidal back-EMF 

    E-print Network

    Ozturk, Salih Baris

    2009-05-15

    This work presents the direct torque control (DTC) techniques, implemented in four- and six-switch inverter, for brushless dc (BLDC) motors with non-sinusoidal back- EMF using two and three-phase conduction modes. First of all, the classical direct...

  2. Conducted RFI emission from an AC-DC converter with sinusoidal line current

    Microsoft Academic Search

    J. Mahdavi; J. Roudet; R. Scheich; J. P. Rognon

    1993-01-01

    The authors discuss the generation and modeling of conducted electromagnetic interference (EMI) in a single-phase AC\\/DC power converter with sinusoidal line current at unity power factor. The converter is composed of a diode rectifier and a conventional boost converter with pulsewidth modulation (PWM) control. Due to this control mode the input current has a very low content of harmonics (the

  3. Comparison of adaptive lattice filters to LMS transversal filters for sinusoidal cancellation

    Microsoft Academic Search

    Richard C. North; J. R. Zeidler; T. R. Albert; W. H. Ku

    1992-01-01

    The authors compare the performance of the recursive least squares lattice (RLSL) and the normalized step-size stochastic gradient lattice (SGL) algorithms to that of the least mean square (LMS) transversal algorithm for the cancellation of sinusoidal interference. It is found that adaptive lattice filters possess a number of advantages over the LMS transversal filter, making them the preferred adaptive noise

  4. Dynamic sorption and hygroexpansion of wood wafers exposed to sinusoidally varying humidity

    Microsoft Academic Search

    A. Chomcharn; C. Skaar

    1983-01-01

    Round wood wafers, 4 mm thick along the grain and 2 cm in cross-sectional diameter, of green basswood (Tilia americana L.), yellow birch (Betula alleghaniensis Britton), and black cherry (Prunus serotina Ehrh.), and initially dried to equilibrium in air of 77% relative humidity and 25°C, were exposed to sinusoidally varying relative humidity between 77 and 47% at 25°C for many

  5. Fan Drive Starting into Naturally Rotating Load by Sinusoidal Sensorless Permanent Magnet Motor Control

    Microsoft Academic Search

    A. Borisavljevic; E. Ho; T. Takahashi

    2006-01-01

    A permanent magnet (PM) motor is a primary motor of choice for small fan motor drive applications. A traditional fan drive based on a permanent magnet motor uses position feedback sensors such as Hall effect sensors. Recently PM motor drive with sinusoidal current and no position sensor has been demanded for many applications including air conditioner outdoor unit fan control.

  6. INTERACTION OF ELECTROMAGNETIC WAVE AND PLASMA SLAB WITH PARTIALLY LINEAR AND SINUSOIDAL ELECTRON DENSITY PROFILE

    Microsoft Academic Search

    S. Gurel; Emrah Oncu

    2009-01-01

    Interaction of an electromagnetic wave and an inhomoge- neous plasma slab with electron distribution in the form of partially linear and sinusoidal proflles is analysed to determine new re?ection, absorbtion and transmission characteristics. Broadband and tunable absorbtion performance of the plasma layer accompanied with narrow- band re?ection characteristic is presented as the function of electron density proflle parameters and external

  7. Sinusoidal oscillation of the ankle as a means of evaluating the spastic patient.

    PubMed Central

    Gottlieb, G L; Agarwal, G C; Penn, R

    1978-01-01

    Sinusoidally modulated torque was applied to rotate the ankle joint of normal subjects and clinically spastic patients. Measurements were made of the effective joint compliance and of the evoked EMG activity. These procedures provide a well-quantified and reliable measure of muscle tone and hyperreflexia which is well correlated with the patient's clinical status. PMID:621528

  8. An Ultra-Low Voltage Analog Front End for Strain Gauge Sensory System Application in 0.18µm CMOS

    NASA Astrophysics Data System (ADS)

    Edward, Alexander; Chan, Pak Kwong

    This paper presents analysis and design of a new ultra-low voltage analog front end (AFE) dedicated to strain sensor applications. The AFE, designed in 0.18µm CMOS process, features a chopper-stabilized instrumentation amplifier (IA), a balanced active MOSFET-C 2nd order low pass filter (LPF), a clock generator and a voltage booster which operate at supply voltage (Vdd) of 0.6V. The designed IA achieves 30dB of closed-loop gain, 101dB of common-mode rejection ratio (CMRR) at 50Hz, 80dB of power-supply rejection ratio (PSRR) at 50Hz, thermal noise floor of 53.4 nV/?Hz, current consumption of 14µA, and noise efficiency factor (NEF) of 9.7. The high CMRR and rail-to-rail output swing capability is attributed to a new low voltage realization of the active-bootstrapped technique using a pseudo-differential gain-boosting operational transconductance amplifier (OTA) and proposed current-driven bulk (CDB) biasing technique. An output capacitor-less low-dropout regulator (LDO), with a new fast start-up LPF technique, is used to regulate this 0.6V supply from a 0.8-1.0V energy harvesting power source. It achieves power supply rejection (PSR) of 42dB at frequency of 1MHz. A cascode compensated pseudo differential amplifier is used as the filter's building block for low power design. The filter's single-ended-to-balanced converter is implemented using a new low voltage amplifier with two-stage common-mode cancellation. The overall AFE was simulated to have 65.6dB of signal-to-noise ratio (SNR), total harmonic distortion (THD) of less than 0.9% for a 100Hz sinusoidal maximum input signal, bandwidth of 2kHz, and power consumption of 51.2µW. Spectre RF simulations were performed to validate the design using BSIM3V3 transistor models provided by GLOBALFOUNDRIES 0.18µm CMOS process.

  9. Breaking the power delivery wall using voltage stacking

    Microsoft Academic Search

    Kaushik Mazumdar; Mircea Stan

    2012-01-01

    We propose the use of voltage stacking for addressing some of the power delivery issues for many-core processors. To demonstrate the effectiveness of our method we first design a proxy for a many-core stacked processor in the form of a regular structure using multiple ring oscillators where we can control the voltage, frequency and switching activity for individual rings. For

  10. DCS1800/WCDMA ADAPTIVE VOLTAGE-CONTROLLED OSCILLATOR

    E-print Network

    Serdijn, Wouter A.

    DCS1800/WCDMA ADAPTIVE VOLTAGE-CONTROLLED OSCILLATOR Aleksandar Tasiü, Wouter A. Serdijn and John R, an adaptive 2G/3G voltage-controlled oscillator (VCO) is described in this paper. For the DCS1800 operation the systems requirements in both the 1.8GHz DCS1800 and the 2.2GHz WCDMA frequency band. The oscillator

  11. A Novel Zero-Voltage Switching Resonant Pole Inverter

    Microsoft Academic Search

    Sanbo Pan; Junmin Pan

    2006-01-01

    In order to realize a simple topology, high efficiency, high frequency, low voltage stress, easy to control soft switching three phase inverter, this paper introduces a novel resonant pole three phase inverter, which realized the zero-voltage switching of the main switches, zero-current switching of auxiliary switches and possesses the small power auxiliary circuit and full PWM capability. It avoids the

  12. Investigation on RFI effects in bandgap voltage references

    Microsoft Academic Search

    F. Fiori; P. S. Crovetti

    2004-01-01

    In this paper the susceptibility of integrated bandgap voltage references to Radio Frequency Interference (RFI) is investigated by on-chip measurements carried out on Kuijk and Tsividis bandgap circuits. These measurements highlight the offset in the reference voltage induced by continuous wave RFI and the complete failures which may be experienced by bandgap circuits. The role of the susceptibility of the

  13. Shrinking stability regions and voltage collapse in power systems

    Microsoft Academic Search

    Khoi T. Vu; Chen-Ching Liu

    1992-01-01

    The dynamic process of voltage collapse is analyzed based on three mechanisms: on-load tap-changing, load dynamics, and generator excitation limiting. The interaction among these mechanisms and how the voltage collapse takes place are thoroughly investigated in a general interconnected network model under the assumption that system frequency remains unchanged. It is found that, so long as an equilibrium exists, there

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

    SciTech Connect

    Peng, Fang Zheng [Tennessee Univ., Knoxville, TN (United States)]|[Oak Ridge National Lab., TN (United States); Lai, Jih-Sheng; McKeever, J.; VanCoevering, J. [Oak Ridge National Lab., TN (United States)

    1995-09-01

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

  15. Level dependent signal flow in the light pupil reflex. II. Phase velocity of responses to sinusoidal light stimuli.

    PubMed

    Myers, G A; Gannon, J A; Stark, L W

    1993-01-01

    Pupillary responses to sinusoidal light stimuli were measured over a range of light levels and frequencies. The phase lag and equivalent time delay of these responses were reduced in an approximately log-linear fashion with increasing mean light level (slope = -60 ms/log unit). The magnitude of this level dependence is reduced at higher frequencies, and at higher light levels. This nonlinear level dependent signal flow (LDSF) effect is shown to be essentially independent of target distance (accommodative stimulus) which influences pupil size, and of pupil size itself. Thus most of the level dependence probably resides in the afferent path of the light-pupil reflex arc, before the accommodation signal joins the light signal in the Edinger-West-phal nucleus. A systems model is presented to the LDSF effect described here and in the companion papers (Myers and Stark 1993a, b). When parameters of the model are adjusted to fit pupillary responses to transient light stimuli over a range of light levels, the model simulates reduced phase lag in response to increased mean light level, and the reduction in this LDSF effect with increased mean light level or increasing stimulus frequency without further changes in parameters. This latter reduction explains the relatively small level dependence seen in latency data (-34 ms/log unit). These data will be shown (Myers and Stark 1990b) to be commensurate with reduction in pupil cycle time (increased frequency of oscillation) observed in high gain oscillation experiments as mean brightness increases.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8452892

  16. Low Loss Snubber for Reducing Motor Terminal Surge Voltage

    NASA Astrophysics Data System (ADS)

    Kon, Hironobu

    The The development of advanced Insulated Gate Bipolar Transistor (IGBT) has enabled high-frequency switching operation and has improved the performance of PWM inverters for motor drive. However, the high rate of dv/dt of IGBT has adverse effects on motor insulation stress. In many motor drive applications, the inverter and motor are separated and it requires long motor feds. The long cable contributes high frequency ringing at the motor terminal and it results in high surge voltage which stresses the motor insulation. The inverter output filter and RDC snubber are conventional method which can reduce the surge voltage. In this paper, we propose the new low loss snubber to reduce the motor terminal surge voltage. The snubber consists of the series connection of charging/discharging capacitor and the voltage-clamped capacitor. At IGBT turn-off, the snubber starts to operate when the IGBT voltage reaches the voltage-clamped level. Since dv/dt is decreased by snubber operating, the peak level of the surge voltage can be reduced. Also the snubber operates at the IGBT voltage above the voltage-clamped level, the snubber loss is largely reduced comparing with RDC snubber. The proposed snubber enables to reduce the motor terminal surge voltage with low loss.

  17. Age and Individual Differences in Controlled Force Exertion Measured by a Computer-Generated Sinusoidal and Quasi-Random Display

    ERIC Educational Resources Information Center

    Nagasawa, Yoshinori; Demura, Shinichi

    2010-01-01

    This study examined age group and individual differences in controlled force exertion by emulating sinusoidal and quasi-random waveforms in 222 right-handed female adults aged 20 to 86 years. The subjects matched their submaximal grip strength by the dominant hand to changing demand values displayed as either a sinusoidal or a quasi-random…

  18. Prediction of spectral shifts proportional to source distances by time-varying frequency or wavelength selection

    E-print Network

    Guruprasad, V

    2008-01-01

    Any frequency selective device with an ongoing drift will cause observed spectra to be variously and simultaneously scaled in proportion to their source distances. The reason is that detectors after the drifting selection will integrate instantaneous electric or magnetic field values from successive sinusoids, and these sinusoids would differ in both frequency and phase. Phase differences between frequencies are ordinarily irrelevant, and recalibration procedures at most correct for frequency differences. With drifting selection, however, each integrated field value comes from *the sinusoid of the instantaneously selected frequency at its instantaneous received phase*, hence the waveform constructed by the integration will follow the drifting selection with a phase acceleration given by the drift rate times the slope of the received phase spectrum. A phase acceleration is literally a frequency shift, and the phase spectrum slope of a received waveform is an asymptotic measure of the source distance, as the pa...

  19. Analytical model for the radio-frequency sheath.

    PubMed

    Czarnetzki, Uwe

    2013-12-01

    A simple analytical model for the planar radio-frequency (rf) sheath in capacitive discharges is developed that is based on the assumptions of a step profile for the electron front, charge exchange collisions with constant cross sections, negligible ionization within the sheath, and negligible ion dynamics. The continuity, momentum conservation, and Poisson equations are combined in a single integro-differential equation for the square of the ion drift velocity, the so called sheath equation. Starting from the kinetic Boltzmann equation, special attention is paid to the derivation and the validity of the approximate fluid equation for momentum balance. The integrals in the sheath equation appear in the screening function which considers the relative contribution of the temporal mean of the electron density to the space charge in the sheath. It is shown that the screening function is quite insensitive to variations of the effective sheath parameters. The two parameters defining the solution are the ratios of the maximum sheath extension to the ion mean free path and the Debye length, respectively. A simple general analytic expression for the screening function is introduced. By means of this expression approximate analytical solutions are obtained for the collisionless as well as the highly collisional case that compare well with the exact numerical solution. A simple transition formula allows application to all degrees of collisionality. In addition, the solutions are used to calculate all static and dynamic quantities of the sheath, e.g., the ion density, fields, and currents. Further, the rf Child-Langmuir laws for the collisionless as well as the collisional case are derived. An essential part of the model is the a priori knowledge of the wave form of the sheath voltage. This wave form is derived on the basis of a cubic charge-voltage relation for individual sheaths, considering both sheaths and the self-consistent self-bias in a discharge with arbitrary symmetry. The externally applied rf voltage is assumed to be sinusoidal, although the model can be extended to arbitrary wave forms, e.g., for dual-frequency discharges. The model calculates explicitly the cubic correction parameter in the charge-voltage relation for the case of highly asymmetric discharges. It is shown that the cubic correction is generally moderate but more pronounced in the collisionless case. The analytical results are compared to experimental data from the literature obtained by laser electric field measurements of the mean and dynamic fields in the capacitive sheath for various gases and pressures. Very good agreement is found throughout. PMID:24483571

  20. Silicon-Germanium Voltage-Controlled Oscillator at 105 GHz

    NASA Technical Reports Server (NTRS)

    Wong, Alden; Larocca, Tim; Chang, M. Frank; Samoska, Lorene A.

    2011-01-01

    A group at UCLA, in collaboration with the Jet Propulsion Laboratory, has designed a voltage-controlled oscillator (VCO) created specifically for a compact, integrated, electronically tunable frequency generator useable for submillimeter- wave science instruments operating in extreme cold environments.

  1. Low voltage to high voltage level shifter and related methods

    NASA Technical Reports Server (NTRS)

    Mentze, Erik J. (Inventor); Hess, Herbert L. (Inventor); Buck, Kevin M. (Inventor); Cox, David F. (Inventor)

    2006-01-01

    A shifter circuit comprises a high and low voltage buffer stages and an output buffer stage. The high voltage buffer stage comprises multiple transistors arranged in a transistor stack having a plurality of intermediate nodes connecting individual transistors along the stack. The transistor stack is connected between a voltage level being shifted to and an input voltage. An inverter of this stage comprises multiple inputs and an output. Inverter inputs are connected to a respective intermediate node of the transistor stack. The low voltage buffer stage has an input connected to the input voltage and an output, and is operably connected to the high voltage buffer stage. The low voltage buffer stage is connected between a voltage level being shifted away from and a lower voltage. The output buffer stage is driven by the outputs of the high voltage buffer stage inverter and the low voltage buffer stage.

  2. Single Event Transients in Low Voltage Dropout (LVDO) Voltage Regulators

    NASA Technical Reports Server (NTRS)

    LaBel, K.; Karsh, J.; Pursley, S.; Kleyner, I.; Katz, R.; Poivey, C.; Kim, H.; Seidleck, C.

    2006-01-01

    This viewgraph presentation reviews the use of Low Voltage Dropout (LVDO) Voltage Regulators in environments where heavy ion induced Single Event Transients are a concern to the designers.Included in the presentation are results of tests of voltage regulators.

  3. Effects of increasing switching frequency in frequency modulated power converters

    Microsoft Academic Search

    Janis Jankovskis; Deniss Stepins; Dmitrijs Pikulins

    2010-01-01

    The paper considers the effect of increasing switching frequency on a frequency modulated (FM) buck converter parameters: efficiency, output voltage ripples and electromagnetic interference (EMI) attenuations. The converter operating in continuous and discontinuous conduction modes (CCM and DCM respectively) is analyzed analytically, by simulations in Simulink and experimentally. The results obtained show that increasing switching frequency can significantly reduce the

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

    SciTech Connect

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

    2009-01-01

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

  5. Growth mechanisms study of microcrystalline silicon deposited by SiH4/H2 plasma using tailored voltage waveforms

    NASA Astrophysics Data System (ADS)

    Bruneau, B.; Wang, J.; Dornstetter, J.-C.; Johnson, E. V.

    2014-02-01

    The use of Tailored Voltage Waveforms is a technique wherein one uses non-sinusoidal waveforms with a period equivalent to RF frequencies to excite a plasma. It has been shown to be an effective technique to decouple maximum Ion Bombardment Energy (IBE) from the ion flux at the surface of the electrodes. In this paper, we use it for the first time as a way to scan through the IBE in order to study the growth mechanism of hydrogenated microcrystalline silicon using a SiH4/H2 chemistry. We find that at critical energies, a stepwise increase in the amorphous to microcrystalline transition thickness is observed, as detected by Real Time Spectroscopic Ellipsometry. The same energy thresholds (30 eV and 70 eV) are found to be very influential on the final surface morphology of the samples, as observed by Atomic Force Microscopy. These thresholds correspond to SiHx+ bulk displacement (30 eV) and Hx+ (70 eV) surface displacement energies. A model is therefore proposed to account for the impact of these ions on the morphology of ?c-Si:H growth.

  6. Advanced High Power DC-DC Converter using A Novel Type Voltage Source Full-Bridge Soft-Switching PWM Inverter with High Frequency Transformer Link for Arc Welding Applications

    Microsoft Academic Search

    Keiki Morimoto; Toshimitsu Doi; Haruhiko Manabe; Tarek Ahmed; Eiji Hiraki; Hyun-Woo Lee; Mutsuo Nakaoka

    2006-01-01

    This paper presents a new circuit topology of full-bridge soft-switching PWM inverter linked DC-DC power converter composed of conventional full-bridge high frequency PWM inverter with high frequency transformer and an active quasi-resonant snubber consisting of an additional power switching device in series with DC busline and a lossless capacitor in parallel with DC busline. Under this proposed high frequency soft-switching

  7. Generating Electrical Voltage

    NSDL National Science Digital Library

    Teachers' Domain presents this interactive lesson designed to help students "learn how a generator converts mechanical energy into electrical energy. Investigate the principle of magnetic induction by moving a conductor through a magnetic field to see how voltage is generated." The lesson is divided into three major sections: How Do Generators Work?, What Factors Influence Voltage Strength?, and What Determines Voltage Polarity? There are plenty of animations to help students visualize the processes at work in electricity generation. On the site, visitors will also find a supplemental background essay, discussion questions, and standards alignment from Teachers' Domain.

  8. TIME-FREQUENCY-MODULATION REPRESENTATION OF STOCHASTIC SIGNALS Philip J.B. Jackson

    E-print Network

    Jackson, Philip JB

    TIME-FREQUENCY-MODULATION REPRESENTATION OF STOCHASTIC SIGNALS Philip J.B. Jackson Centre discrete signals with time- varying parameters, and extended to a 3D time-frequency- modulation modulation (AM) systems, the carrier signal is a sinusoid of much higher frequency than those

  9. Frequency-Space Decomposition and Acquisition of Light Transport under Spatially Varying

    E-print Network

    O'Brien, James F.

    Frequency-Space Decomposition and Acquisition of Light Transport under Spatially Varying are redundant either in the spatial or the frequency domain and can be separated using appropriate illumination- fer in their response to different frequencies of sinusoidal illumination patterns, #12;2 D. Reddy, R

  10. On the Variety of Spatial Frequency Selectivities Shown by Neurons in Area 17 of the Cat

    Microsoft Academic Search

    D. J. Tolhurst; I. D. Thompson

    1981-01-01

    The amplitudes of the responses of over 300 neurons in area 17 of the cat were examined as a function of the spatial frequency of moving sinusoidal gratings. The optimal spatial frequency and the bandwidth of the tuning curves were determined. The bandwidth varied considerably from neuron to neuron. Neurons optimally responsive to high spatial frequencies tended to have narrower

  11. Operating stability of a self-breakdown spark-gap frequency switch rated at a voltage of 300 kV and a switched power of up to 450 J

    NASA Astrophysics Data System (ADS)

    Koval'chuk, B. M.; Korolev, Yu. D.; Kumpyak, E. V.; Frants, O. B.; Shemyakin, I. A.

    2014-12-01

    A test bench for studying two-electrode spark gaps rated at a voltage of 300 kV and a pulse repetition rate of up to 10 Hz and operating in air at elevated pressure. The typical time of pulse charging of a capacitive storage in the bench equals about 100 ?s. The object of investigation is a spark gap the operating stability of which at a level of 10% of the rate voltage is achieved by initiating a corona discharge at the prebreakdown stage. It is shown that unstable operation is due to the accumulation of nitrogen oxides in the gap. To maintain the oxide content at an acceptable level, continuous gas purging is applied and necessary gas flow rates are estimated.

  12. Optimal condition of memristance enhancement circuit using external voltage source

    NASA Astrophysics Data System (ADS)

    Tanaka, Hiroya; Tadokoro, Yukihiro; Iizuka, Hideo

    2014-05-01

    Memristor provides nonlinear response in the current-voltage characteristic and the memristance is modulated using an external voltage source. We point out by solving nonlinear equations that an optimal condition of the external voltage source exists for maximizing the memristance in such modulation scheme. We introduce a linear function to describe the nonlinear time response and derive an important design guideline; a constant ratio of the frequency to the amplitude of the external voltage source maximizes the memristance. The analysis completely accounts for the memristance behavior.

  13. Threshold voltage extraction circuit 

    E-print Network

    Hoon, Siew Kuok

    2000-01-01

    A novel optimally self-biasing MOSFET threshold-voltage (V[]) extractor circuit is presented. It implements the most popular industrial extraction algorithm of biasing a saturated MOSFET to the linear portion of its [] versus [] characteristic...

  14. Improving membrane voltage measurements

    E-print Network

    Cai, Long

    as fluorescence resonance energy transfer (FRET) donor and acceptor to develop a voltage sensor, named Mermaid activities in cultured excitable cells. Notably, Mermaid has fast on-off kinetics at warm (B33 1C

  15. Threshold voltage extraction circuit

    E-print Network

    Hoon, Siew Kuok

    2000-01-01

    A novel optimally self-biasing MOSFET threshold-voltage (V[]) extractor circuit is presented. It implements the most popular industrial extraction algorithm of biasing a saturated MOSFET to the linear portion of its [] versus [] characteristic...

  16. A simple and self-adapting high-performance current control scheme for three phase voltage source inverters

    Microsoft Academic Search

    Ansgar Ackva; Harry Reinold; Reniigiusz Olesinski

    1992-01-01

    An adaptive optimized regulator (AOR) for three-phase voltage source inverters is presented. The zero-voltage vectors are used systematically to reduce the switching frequency and can be reached by switching only one inverter leg. In the steady stage the controller applies to the machine only those three voltage vectors which are directly adjacent to the machine voltage (similar to pulse width

  17. High-voltage engineering

    Microsoft Academic Search

    Khalifa

    1990-01-01

    The topics covered in this book include gas discharge, insulating materials, system earthing, overvoltage and insulation coordination, and high-voltage equipment and testing techniques. In two chapters, the principles of design of high-voltage busbars are discussed, together with their insulation and ampacity, whether they are of conventional air-insulated type or the metal-clad GIS types now widely used at the HV and

  18. High frequency alternating current power supply for automobile auxiliary electrical systems

    Microsoft Academic Search

    C. Antaloae; J. Marco; N. D. Vaughan

    2010-01-01

    This paper presents an HFAC power source concept for vehicle auxiliary electrical systems. The proposed power supply is based on a resonant DC to HFAC inverter, which constructs the output sinusoidal voltage and current. Mathematical modelling is employed to design the control strategy and Matlab Simulink is used to model and simulate the circuit operation under various load conditions. Simulation

  19. Accurate voltage phasor measurement in a series-compensated network

    SciTech Connect

    Lambert, J.; McNabb, D. (Hydro-Quebec, Montreal, Quebec (Canada)); Phadke, A.G. (Virginia Polytechnic Inst. and State Univ., Blacksburg, VA (United States))

    1994-01-01

    This paper describes the feasibility studies concerning an accurate voltage phasor measurement in series-compensated network undergoing large disturbances. The principal modes of distortions in such a network are described. Some of these modes are changing with the fundamental frequency. The phasor evaluation is based on a new digital filter approach in which the fundamental frequency is estimated using a least-square algorithm. The need to have special potential (voltage) transformers is also discussed. This approach would be used in a shunt reactor switching scheme for an overall voltage control of a transmission network.

  20. Low-voltage gyrotrons

    SciTech Connect

    Glyavin, M. Yu.; Zavolskiy, N. A.; Sedov, A. S. [Institute of Applied Physics RAS, N. Novgorod 603600 (Russian Federation); Nusinovich, G. S. [IREAP, University of Maryland, College Park, Maryland 20742-3511 (United States)

    2013-03-15

    For a long time, the gyrotrons were primarily developed for electron cyclotron heating and current drive of plasmas in controlled fusion reactors where a multi-megawatt, quasi-continuous millimeter-wave power is required. In addition to this important application, there are other applications (and their number increases with time) which do not require a very high power level, but such issues as the ability to operate at low voltages and have compact devices are very important. For example, gyrotrons are of interest for a dynamic nuclear polarization, which improves the sensitivity of the nuclear magnetic resonance spectroscopy. In this paper, some issues important for operation of gyrotrons driven by low-voltage electron beams are analyzed. An emphasis is made on the efficiency of low-voltage gyrotron operation at the fundamental and higher cyclotron harmonics. These efficiencies calculated with the account for ohmic losses were, first, determined in the framework of the generalized gyrotron theory based on the cold-cavity approximation. Then, more accurate, self-consistent calculations for the fundamental and second harmonic low-voltage sub-THz gyrotron designs were carried out. Results of these calculations are presented and discussed. It is shown that operation of the fundamental and second harmonic gyrotrons with noticeable efficiencies is possible even at voltages as low as 5-10 kV. Even the third harmonic gyrotrons can operate at voltages about 15 kV, albeit with rather low efficiency (1%-2% in the submillimeter wavelength region).

  1. Advanced High Power DC-DC Converter using A Novel Type Voltage Source Full-Bridge Soft-Switching PWM Inverter with High Frequency Transformer Link for Arc Welding Applications

    NASA Astrophysics Data System (ADS)

    Morimoto, Keiki; Doi, Toshimitsu; Manabe, Haruhiko; Ahmed, Tarek; Hiraki, Eiji; Lee, Hyun-Woo; Nakaoka, Mutsuo

    This paper presents a new circuit topology of full-bridge soft-switching PWM inverter linked DC-DC power converter composed of conventional full-bridge high frequency PWM inverter with high frequency transformer and an active quasi-resonant snubber consisting of an additional power switching device in series with DC busline and a lossless capacitor in parallel with DC busline. Under this proposed high frequency soft-switching PWM inverter linked DC-DC converter, four power switches in the full-bridge arms and DC busline series switch can achieve ZVS at turn-off commutation. By developing the advanced soft-switching PWM high frequency inverter type DC-DC converter, although the conduction power loss of DC busline series power switch increases a little, the total turn-off switching loss of full-bridge high frequency inverter power modules can be sufficiently lowered more and more in the higher frequency range of 60kHz. As a result, when the switching frequency of high frequency inverter power stage using IGBT power modules is designed so as to be more than about 10kHz, the more the switching frequency of inverter increases, the more this high frequency soft-switching DC-DC converter has remarkable advantage as for the power conversion efficiency as compared with the conventional hard-switching PWM inverter DC-DC converter. Its practical effectiveness of high power density and high performance is actually proved for TIG arc welding equipment in industry.

  2. Voltage collapse proximity index determination using voltage phasors approach

    Microsoft Academic Search

    F. Gubina; B. Strmcnik

    1995-01-01

    In the paper, a “phasor concept” of voltage collapse proximity determination is presented. An adequate voltage proximity index is calculated based on the voltage phasor values only. Furthermore, an algorithm is derived which automatically detects the network transmission paths to the load nodes which are prone to voltage collapse due to additional real or reactive loading. The algorithm is tested

  3. Precision photodetector with frequency output

    SciTech Connect

    Martynyuk, A.S.; Sachkov, A.V.

    1986-04-01

    This paper describes a photodetector whose sensitivity threshold is close to the theoretical limit governed by the thermal noise of the photodiode. successive conversion of photocurrent to voltage and voltage to frequency provides a sensitivity threshold of up to 2.10/sup -13/ W with a nonlinearity of conversion of light intensity to frequency of less than or equal to 0.02% over a dynamic range of 10/sup 7/.

  4. Nonpulsed sinusoidal electromagnetic fields as a noninvasive strategy in bone repair: the effect on human mesenchymal stem cell osteogenic differentiation.

    PubMed

    Ledda, Mario; D'Emilia, Enrico; Giuliani, Livio; Marchese, Rodolfo; Foletti, Alberto; Grimaldi, Settimio; Lisi, Antonella

    2015-02-01

    In vivo control of osteoblast differentiation is an important process needed to maintain the continuous supply of mature osteoblast cells for growth, repair, and remodeling of bones. The regulation of this process has also an important and significant impact on the clinical strategies and future applications of cell therapy. In this article, we studied the effect of nonpulsed sinusoidal electromagnetic field radiation tuned at calcium-ion cyclotron frequency of 50?Hz exposure treatment for bone differentiation of human mesenchymal stem cells (hMSCs) alone or in synergy with dexamethasone, their canonical chemical differentiation agent. Five days of continuous exposure to calcium-ion cyclotron resonance affect hMSC proliferation, morphology, and cytoskeletal actin reorganization. By quantitative real-time polymerase chain reaction, we also observed an increase of osteoblast differentiation marker expression such as Runx2, alkaline phosphatase (ALP), osteocalcin (OC), and osteopontin (OPN) together with the osteoprotegerin mRNA modulation. Moreover, in these cells, the increase of the protein expression of OPN and ALP was also demonstrated. These results demonstrate bone commitment of hMSCs through a noninvasive and biocompatible differentiating physical agent treatment and highlight possible applications in new regenerative medicine protocols. PMID:25087470

  5. Full-range Fourier domain polarization-sensitive optical coherence tomography using sinusoidal phase modulation

    NASA Astrophysics Data System (ADS)

    Chen, Yan; Wang, Xiangzhao; Li, Zhongliang; Nan, Nan; Guo, Xin

    2014-09-01

    We present a full-range Fourier domain polarization-sensitive optical coherence tomography technique which is able to obtain images of retardance, fast optical axis and intensity of sample. In this technique, the sinusoidal phase modulation is introduced into the spectral interferograms while the probe beam scans over the sample (B-scan). Then the complex horizontal and vertical signals are reconstructed by demodulation. By the Fourier transformation of the two interferograms, the full range images are obtained. Herein, the typical linear phase modulation is modified to sinusoidal phase modulation, which improves the system tolerance of sample movements and avoids sensitivity fall-off along the transverse scan. Furthermore, the images are obtained through the recombination of the horizontal and vertical polarization beam components acquired by a single camera, which avoids the problems of synchronous control and alignments in the situation of two cameras.

  6. Reconciling frequency selectivity and phase effects in masking

    Microsoft Academic Search

    Andrew J. Oxenham; Torsten Dau

    2001-01-01

    The effects of auditory frequency selectivity and phase response on masking were studied using harmonic tone complex maskers with a 100-Hz fundamental frequency. Positive and negative Schroeder-phase complexes ~m 1 and m 2 !, were used as maskers and the signal was a long-duration sinusoid. In the first experiment, thresholds for signal frequencies of 1 and 4 kHz were measured

  7. Highly enhanced avalanche probability using sinusoidally-gated silicon avalanche photodiode

    SciTech Connect

    Suzuki, Shingo; Namekata, Naoto, E-mail: nnao@phys.cst.nihon-u.ac.jp; Inoue, Shuichiro [Institute of Quantum Science, Nihon University, 1-8-14 Kanda-Surugadai, Chiyoda-ku, Tokyo 101-8308 (Japan); Tsujino, Kenji [Tokyo Women's Medical University, 8-1 Kawada-cho, Shinjuku-ku, Tokyo 162-8666 (Japan)

    2014-01-27

    We report on visible light single photon detection using a sinusoidally-gated silicon avalanche photodiode. Detection efficiency of 70.6% was achieved at a wavelength of 520?nm when an electrically cooled silicon avalanche photodiode with a quantum efficiency of 72.4% was used, which implies that a photo-excited single charge carrier in a silicon avalanche photodiode can trigger a detectable avalanche (charge) signal with a probability of 97.6%.

  8. Design considerations of sinusoidally excited permanent-magnet Machines for low-torque-ripple applications

    Microsoft Academic Search

    Mohammad S. Islam; Sayeed Mir; Tomy Sebastian; Samuel Underwood

    2005-01-01

    Several high-performance motor drive applications require the motor drive to produce smooth torque with very stringent torque-ripple requirement. This paper is focused on various machine design considerations that can be used in reducing the torque ripple of a sinusoidally excited permanent-magnet brushless dc motor. The paper quantifies the various sources of torque ripple, which may be minimized by appropriate design

  9. Receptor-mediated endocytosis of aldehyde-modified proteins by sinusoidal liver cells

    Microsoft Academic Search

    Seikoh Horiuchi; Kyoko Takata; Masaji Murakami; Yoshimasa Morino

    1987-01-01

    Formaldehyde-treated serum albumin (f-Alb) is known to be endocytosed by sinusoidal lever cells via a receptor-mediated mechanism. The receptor purified from rat livers exhibited a molecular weight of 125,000, consisting of two glycoprotein components with molecular weights of 53,000 and 30,000, respectively. Experiments using antireceptor antibody demonstrated that the f-Alb receptor is distinct from the receptor that mediates endocytotic uptake

  10. Pressure-time characterization of an internal combustion engine with sinusoidal piston travel

    Microsoft Academic Search

    J. Smith; R. Churchill; G. Woodrow

    1987-01-01

    A unique engine configuration called the Stiller-Smith Engine creates a nonconventional pressure versus time response due to the sinusoidal nature of the motion-conversion mechanism. The differences in response are due in part to the utilization of stock piston\\/cylinder assemblies for engineering prototypes, and the elimination of piston dwell. If all other engine considerations were equal, fuel conversion criteria would at

  11. Torque control of sinusoidal PMAC motors for direct-drive robots

    Microsoft Academic Search

    Dong Sun; James K. Mills

    2001-01-01

    A control approach for direct-drive robots with sinusoidal permanent magnet AC (PMAC) motors is developed. The conventional vector control for PMAC motors has been simplified by specifying the motor stator phase so that the rotating d-axis current is zero. This makes the motor work in maximum torque-per-amp operation. The proposed torque control, in the form of torque feedforward plus PI-type

  12. Least squares estimation of 2-D sinusoids in colored noise: Asymptotic analysis

    Microsoft Academic Search

    Guy Cohen; Joseph M. Francos

    2002-01-01

    This paper considers the problem of estimating the parameters of real-valued two-dimensional (2-D) sinusoidal sig- nals observed in colored noise. This problem is a special case of the general problem of estimating the parameters of a real-valued homogeneous random field with mixed spectral distribution from a single observed realization of it. The large sample properties of the least squares (LS)

  13. Improved sinusoidal gating with balanced InGaAs/InP Single Photon Avalanche Diodes.

    PubMed

    Lu, Zhiwen; Sun, Wenlu; Zhou, Qiugui; Campbell, Joe; Jiang, Xudong; Itzler, Mark A

    2013-07-15

    We report balanced InGaAs/InP single photon avalanche diodes (SPADs) operated in sinusoidal gating mode with a tunable phase shifter to reduce common mode noise. This technique enables detection of small avalanche pulses, which results in reduced afterpulsing. For laser repletion rate of 20 MHz at 240 K, the dark count rate for photon detection efficiency of 10% is 8.9 kHz. PMID:23938523

  14. Sensorless control of PMSM drives using a combination of voltage model and HF signal injection

    Microsoft Academic Search

    Antti Piippo; Marko Hinkkanen; Jorma Luomi

    2004-01-01

    This paper presents a method for the rotor speed and position estimation of permanent magnet synchronous motors in a wide speed range including standstill. The proposed method is based on a modified voltage model at high speeds, and combines the modified voltage model with a high-frequency signal injection technique at low speeds. The fast dynamic response of the voltage model

  15. Preliminary results of interfacial space charge formed in laminated dielectrics under AC voltage application

    Microsoft Academic Search

    T. Tanaka; T. Ito; Y. Tanaka; T. Takada

    2000-01-01

    A measurement system was developed to clarify interfacial space charge formation in the dielectric with an interface under ac voltage stress, the frequency of which could be varied from 50 to 0.00007 Hz. Measurement timing was set to eight points in each cycle of applied voltage. Such ac voltage with its peak value of 5, 10 and 15 kV was

  16. Investigation of breakdown voltage curves for pure helium and silane–helium mixtures

    Microsoft Academic Search

    V. Borg Dezani; J. L. Ginoux

    1994-01-01

    The breakdown voltage versus pressure for pure helium and several silane–helium mixtures between coaxial cylinders were measured during an alternative current corona silent discharge at low frequency (3000 Hz) from 104 to 1.5×105 Pa at constant temperature. The differences observed between pure helium breakdown voltages and silane–helium breakdown voltages were analyzed revealing a breakdown streamer mechanism.

  17. A new scheduling technique based on Dynamic Voltage Scaling for MPSoC

    Microsoft Academic Search

    Chang-Woo Park; Kyung-Woo Noh; Seok-Yoon Kim

    2008-01-01

    The DVS(Dynamic Voltage Scaling) technique is the method to reduce the dynamic energy consumption. Using slack times, it extends the execution time of big load operations by changing frequency and voltage of variable voltage processors. Many researches have been going on to control the energy consumption of the processors and the data transmission among processors by controlling the bandwidth to

  18. Parallel flow to analyze the impact of the voltage regulator model in nanoscale power distribution network

    Microsoft Academic Search

    Amirali Shayan Arani; Xiang Hu; He Peng; Wenjian Yu; Wanping Zhang; Chung-kuan Cheng; Mikhail Popovich; Xiaoming Chen; Lew Chua-eoan; Xiaohua Kong

    2009-01-01

    In this paper, an efficient parallel flow for the design of the full power distribution network (PDN) is proposed. The analysis demonstrates the impact of the voltage regulator model in both frequency and time domain response. Based on the experimental results, it is observed that including the voltage regulator model in the PDN model increases the transient voltage drop and

  19. Comparison between quasi-sinusoidal and quasi-triangular profiles for diffraction gratings printed on acetates

    NASA Astrophysics Data System (ADS)

    Mora-González, Miguel; Chiu-Zarate, Roger; Muñoz-Maciel, Jesús; Peña-Lecona, Francisco G.; Pérez Ladrón de Guevara, Héctor; Casillas, Francisco J.

    2011-10-01

    The aim of this work is to propose the use of printed acetate sheets as quasi-sinusoidal and quasi-triangular diffraction gratings, as low-cost alternative gratings for application in non-invasive optical tests. Gratings were generated with Matlab® software and made with various models of laser and inkjet printers. A study of the profile gratings that depend on the symmetry in the sample was included, gratings were placed in the entrance pupil of a positive lens (illuminated by a collimated plane wave) to observe their Fourier transforms. It was found that diffraction patterns of various types of quasi-sinusoidal and quasi-triangular profiles were very close to that of sinusoidal gratings. Gradual change in the size of printed ink spots was observed in more detail through a magnification of 40x. Additionally, an atomic force microscope was used to measure the average superficial roughness of the impressions as to observe the behavior of the ink on the acetate.

  20. Effect of Caloric Restriction on Hepatic Sinusoidal System and Stellate Cells in Mice

    PubMed Central

    Chen, Jian; King, Kara; Zhang, Jian X.

    2014-01-01

    Aging associated changes in liver include reduced hepatic blood flow, increased number of stellate cells, and collagen deposits in perisinusoidal space. We tested the possibility of mitigating these changes with caloric restriction. Two-month-old mice were subjected to 30 percent caloric restriction for 12 months and then examined for the effect of caloric restriction on the sinusoidal network, collagen deposition, and the number of stellate cells. Using intravital fluorescence microscopy, assessments were made on sinusoidal diameter, density, volumetric flow, perfusion index, and autofluorescence of vitamin A that was primarily stored with lipid droplets in stellate cells. A significant effect was observed in the vitamin A autofluorescence of stellate cells; stellate cell associated fluorescence was diminished in terms of number and size of fluorescent spots. Caloric restriction reduced collagen deposits in liver sections and lowered the gene expression of ?1-(I) collagen but not ?-smooth muscle actin. No differences were detected in sinusoidal dimension measurements. Our results showed that caloric restriction was effective in ameliorating the increase in stellate cells and the mild fibrosis in old mice. However, caloric restriction had no impact on stellate cell activity level as indicated by the unaffected ?-smooth muscle actin expression. PMID:24649364

  1. Basic study of transient breakdown voltage in solid dielectric cables

    NASA Astrophysics Data System (ADS)

    Bahder, G.; Sosnowski, M.; Katz, C.

    1980-09-01

    A comprehensive review of the technical and scientific publications relating to crosslinked polyethylene (XLPE) and ethylene propylene rubber (EPR) insulated cables revealed that there is very little known with respect to the life expectancy, the final factory voltage test background and the mechanism of voltage breakdown of these cables. A new methodology for the investigation of breakdown voltages of XLPE and EPR insulated cables was developed which is based on the investigation of breakdown voltages at various voltage transients such as unipolarity pulses and dual-polarity pulses, and a.c. voltage at power and high frequency. Also, a new approach to statistical testing was developed which allows one to establish a correlation among the breakdown voltages obtained with various voltage transients. Finally, a method for the determination of threshold voltage regardless of the magnitude of apparent charge was developed. A model of breakdown and electrical aging of XLPE and EPR insulated cables was developed as well as life expectancy characteristics for high voltage stress XLPE insulated cables operated in a dry environment at room temperature and at 900 C.

  2. High voltage variable diameter insulator

    DOEpatents

    Vanacek, D.L.; Pike, C.D.

    1982-07-13

    A high voltage feedthrough assembly having a tubular insulator extending between the ground plane ring and the high voltage ring. The insulator is made of Pyrex and decreases in diameter from the ground plane ring to the high voltage ring, producing equipotential lines almost perpendicular to the wall of the insulator to optimize the voltage-holding capability of the feedthrough assembly.

  3. Sinusoidal Graphs

    NSDL National Science Digital Library

    Kahl, Nathan

    Created by Nathan Kahl for the Connected Curriculum Project, the purpose of this module is to study properties of the graphs of the basic trigonometric functions, sine and cosine. This is one within a much larger set of learning modules hosted by Duke University.

  4. Electron launching voltage monitor

    DOEpatents

    Mendel, Clifford W. (Albuquerque, NM); Savage, Mark E. (Albuquerque, NM)

    1992-01-01

    An electron launching voltage monitor measures MITL voltage using a relationship between anode electric field and electron current launched from a cathode-mounted perturbation. An electron launching probe extends through and is spaced from the edge of an opening in a first MITL conductor, one end of the launching probe being in the gap between the MITL conductor, the other end being adjacent a first side of the first conductor away from the second conductor. A housing surrounds the launching probe and electrically connects the first side of the first conductor to the other end of the launching probe. A detector detects the current passing through the housing to the launching probe, the detected current being representative of the voltage between the conductors.

  5. Responses of non-eye movement central vestibular neurons to sinusoidal horizontal translation in compensated macaques after unilateral labyrinthectomy.

    PubMed

    Newlands, Shawn D; Lin, Nan; Wei, Min

    2014-07-01

    After vestibular labyrinth injury, behavioral deficits partially recover through the process of vestibular compensation. The present study was performed to improve our understanding of the physiology of the macaque vestibular system in the compensated state (>7 wk) after unilateral labyrinthectomy (UL). Three groups of vestibular nucleus neurons were included: pre-UL control neurons, neurons ipsilateral to the lesion, and neurons contralateral to the lesion. The firing responses of neurons sensitive to linear acceleration in the horizontal plane were recorded during sinusoidal horizontal translation directed along six different orientations (30° apart) at 0.5 Hz and 0.2 g peak acceleration (196 cm/s(2)). This data defined the vector of best response for each neuron in the horizontal plane, along which sensitivity, symmetry, detection threshold, and variability of firing were determined. Additionally, the responses of the same cells to translation over a series of frequencies (0.25-5.0 Hz) either in the interaural or naso-occipital orientation were obtained to define the frequency response characteristics in each group. We found a decrease in sensitivity, increase in threshold, and alteration in orientation of best responses in the vestibular nuclei after UL. Additionally, the phase relationship of the best neural response to translational stimulation changed with UL. The symmetry of individual neuron responses in the excitatory and inhibitory directions was unchanged by UL. Bilateral central utricular neurons still demonstrated two-dimension tuning after UL, consistent with spatio-temporal convergence from a single vestibular end-organ. These neuronal data correlate with known behavioral deficits after unilateral vestibular compromise. PMID:24717349

  6. PHONETIC PERCEPTION OF SINUSOIDAL SIGNALS: EFFECTS OF AMPLITUDE VARIATION* Robert E. Remez,+ Philip E. Rubin, and Thomas D. Carrell++

    E-print Network

    PHONETIC PERCEPTION OF SINUSOIDAL SIGNALS: EFFECTS OF AMPLITUDE VARIATION* Robert E. Remez,+ Philip, are capable of transcribing the phonetic message of acoustic signals consisting solely of time stimulus. Phonetic and syllabic intelligibility were compared in four conditions: (1) normal amplitude

  7. Characterization of Frequency Stability

    Microsoft Academic Search

    James A. Barnes; Andrew R. Chi; Leonard S. Cutler; Daniel J. Healey; David B. Leeson; Thomas E. McGunigal; James A. Mullen; Warren L. Smith; Richard L. Sydnor; Robert F. C. Vessot; Gernot M. R. Winkler

    1971-01-01

    Consider a signal generator whose instantaneous output voltage V(t) may be written as V(t) = [V0 + ??(t)] sin [2??v0t + s(t)] where V0 and v0 are the nominal amplitude and frequency, respectively, of the output. Provided that ??(t) and ??(t) = (d??\\/(dt) are sufficiently small for all time t, one may define the fractional instantaneous frequency deviation from nominal

  8. Accurate voltage phasor measurement in a series-compensated network

    Microsoft Academic Search

    J. Lambert; D. McNabb; A. G. Phadke

    1994-01-01

    This paper describes the feasibility studies concerning an accurate voltage phasor measurement in series-compensated network undergoing large disturbances. The principal modes of distortions in such a network are described. Some of these modes are changing with the fundamental frequency. The phasor evaluation is based on a new digital filter approach in which the fundamental frequency is estimated using a least-square

  9. Subthreshold voltage noise of rat neocortical pyramidal neurones

    PubMed Central

    Jacobson, Gilad A; Diba, Kamran; Yaron-Jakoubovitch, Anat; Oz, Yasmin; Koch, Christof; Segev, Idan; Yarom, Yosef

    2005-01-01

    Neurones are noisy elements. Noise arises from both intrinsic and extrinsic sources, and manifests itself as fluctuations in the membrane potential. These fluctuations limit the accuracy of a neurone's output but have also been suggested to play a computational role. We present a detailed study of the amplitude and spectrum of voltage noise recorded at the soma of layer IV–V pyramidal neurones in slices taken from rat neocortex. The dependence of the noise on holding potential, synaptic activity and Na+ conductance is systematically analysed. We demonstrate that voltage noise increases non-linearly as the cell depolarizes (from a standard deviation (s.d.) of 0.19 mV at ?75 mV to an s.d. of 0.54 mV at ?55 mV). The increase in voltage noise is accompanied by an increase in the cell impedance, due to voltage dependence of Na+ conductance. The impedance increase accounts for the majority (70%) of the voltage noise increase. The increase in voltage noise and impedance is restricted to the low-frequency range (0.2–2 Hz). At the high frequency range (5–100 Hz) the voltage noise is dominated by synaptic activity. In our slice preparation, synaptic noise has little effect on the cell impedance. A minimal model reproduces qualitatively these data. Our results imply that ion channel noise contributes significantly to membrane voltage fluctuations at the subthreshold voltage range, and that Na+ conductance plays a key role in determining the amplitude of this noise by acting as a voltage-dependent amplifier of low-frequency transients. PMID:15695244

  10. Full bridge ZCS PWM converter for high-voltage high-power applications

    Microsoft Academic Search

    CHRIS IANNELLO; SHIGUO LUO; ISSA BATARSEH

    2002-01-01

    This paper presents a comprehensive study of a full bridge (FB) zero-current switched (ZCS) PWM converter which is suitable for high-voltage and high-power DC application that achieves ZCS for all active switches, and zero-voltage-switched (ZVS) operation for all diodes on the high voltage side. The given converter utilizes component parasitic parameters, particularly for the high-voltage transformer, and employs fixed-frequency phase-shift

  11. Fourier Analysis of Sinusoidally Driven Thalamocortical Relay Neurons and a Minimal Integrate-and-Fire-or-Burst Model

    Microsoft Academic Search

    GREGORY D. SMITH; CHARLES L. COX; S. MURRAY SHERMAN; JOHN RINZEL

    2000-01-01

    John Rinzel. Fourier analysis of sinusoidally driven thalamocortical relay neurons and a minimal integrate-and-fire-or-burst model. J. Neurophysiol.83: 588 - 610, 2000. We performed intracellular record- ings of relay neurons from the lateral geniculate nucleus of a cat thalamic slice preparation. We measured responses during both tonic and burst firing modes to sinusoidal current injection and performed Fourier analysis on these

  12. High resolution Joint Time Delay and Frequency Estimation

    Microsoft Academic Search

    Shatnawi Heba; Gami Hiren; M. M. Qasaymeh; Tayem Nizar; M. E. Sawan; R. Pendse

    2009-01-01

    Joint Time Delay and Frequency Estimation (JTDFE) problem of complex sinusoidal signals received at two separated sensors is an attractive problem that has been studied for many engineering applications. In this paper, the Rank-Revealing QR factorization is applied to the real data matrix obtained via the unitary transformation of the square Toeplitz complex data matrix. Then the MUSIC spectrum estimation

  13. FREQUENCY RESPONSE OF A PHOTO-VISCOELASTIC MATERIAL

    Microsoft Academic Search

    G. W. Brown; D. R. Selway

    1963-01-01

    An electromagnetic shaker was used to apply sinusoidal axial ; displacements to one end of a column of Hysol 4364, an optically sensitive ; urethane rubber compound of low modulus. The nondriven end of the column was ; free. The column was excited at frequencies of 81, 244, 424, 603, and 783 cps, ; corresponding to the first five resonant

  14. Impairment of human proprioception by high-frequency cutaneous vibration

    PubMed Central

    Weerakkody, N S; Mahns, D A; Taylor, J L; Gandevia, S C

    2007-01-01

    These experiments assessed whether the impairment in proprioceptive acuity in the hand during ‘interfering’ cutaneous stimulation could be caused by inputs from Pacinian corpuscles. The ability to detect passive movements at the proximal interphalangeal joint of the index finger was measured when vibrotactile stimuli were applied to the adjacent middle finger and thenar eminence at frequencies and amplitudes that favour activation of rapidly adapting cutaneous afferents. Inputs from Pacinian corpuscles are favoured with high-frequency vibration (300 Hz), while those from Meissner corpuscles are favoured by lower frequencies (30 Hz). Detection of movement was significantly impaired when 300 Hz (20 ?m peak-to-peak amplitude) complex vibration or 300 Hz (50 ?m) sinusoidal vibration was applied to the middle finger and thenar eminence. In contrast, detection of movements was not altered by low-frequency sinusoidal vibration at 30 Hz with an amplitude of 50 ?m or with a larger amplitude matched in subjective intensity to the 300 Hz sinusoidal stimulus. Thus it is unlikely that the impairment in detection was due to attention being diverted by vibration of an adjacent digit. In addition, an increase in amplitude of 300 Hz vibration led to a greater impairment of movement detection, so that the impairment was graded with the input. The time taken to nominate the direction of applied movement also increased during 300 Hz but not during 30 Hz sinusoidal vibration. These findings suggest that stimuli which preferentially activate Pacinian, but not Meissner corpuscles, impair proprioceptive acuity in a movement detection task. PMID:17412774

  15. Development of an optical instrument transformer for DC voltage measurement

    SciTech Connect

    Kurosawa, K.; Yoshida, S. (Tokyo Electric Power Co. (Japan)); Mori, E.; Takahashi, G.; Saito, S. (Hitachi Ltd., Tokyo (Japan))

    1993-10-01

    This paper deals with the principles, design, assembly, testing results and practical application of a new type of optical voltage instrument transformer based on the Pockels effect, developed for the measurement of DC voltage, with a view to the protection and control of DC power transmission systems including frequency changer power equipment. In order to develop more accurate devices, the authors conceived a new scheme capable of overcoming the particular problems of DC voltage measurement which cause measurement errors. In this scheme, the DC voltage to be measured is chopped and applied to the Pockels crystal. An optical DC voltage instrument transformer was developed and tested using this scheme. The results of the factory tests showed that the characteristics of the new device conform with the required specifications of DC voltage instrument transformers for the protection and control of frequency changer power equipment. The results of field tests conducted for 1 year at an operating frequency conversion substation confirmed that the device is of adequate reliability. The new device has been practically applied in a frequency conversion power system of the Tokyo Electric Power Co., Inc since May 1992.

  16. A fast and accurate single frequency estimator

    Microsoft Academic Search

    STEVEN KAY

    1989-01-01

    A novel frequency estimator for a single complex sinusoid in complex white Gaussian noise is proposed. The estimator is more computationally efficient that the optimal maximum-likelihood estimator yet attains equally good performance at moderately high signal-to-noise ratios. The estimator is shown to be related to the linear prediction estimator. This relationship is used to reveal why the linear prediction estimator

  17. Encoding frequency contrast in primate auditory cortex

    PubMed Central

    Scott, Brian H.; Semple, Malcolm N.

    2014-01-01

    Changes in amplitude and frequency jointly determine much of the communicative significance of complex acoustic signals, including human speech. We have previously described responses of neurons in the core auditory cortex of awake rhesus macaques to sinusoidal amplitude modulation (SAM) signals. Here we report a complementary study of sinusoidal frequency modulation (SFM) in the same neurons. Responses to SFM were analogous to SAM responses in that changes in multiple parameters defining SFM stimuli (e.g., modulation frequency, modulation depth, carrier frequency) were robustly encoded in the temporal dynamics of the spike trains. For example, changes in the carrier frequency produced highly reproducible changes in shapes of the modulation period histogram, consistent with the notion that the instantaneous probability of discharge mirrors the moment-by-moment spectrum at low modulation rates. The upper limit for phase locking was similar across SAM and SFM within neurons, suggesting shared biophysical constraints on temporal processing. Using spike train classification methods, we found that neural thresholds for modulation depth discrimination are typically far lower than would be predicted from frequency tuning to static tones. This “dynamic hyperacuity” suggests a substantial central enhancement of the neural representation of frequency changes relative to the auditory periphery. Spike timing information was superior to average rate information when discriminating among SFM signals, and even when discriminating among static tones varying in frequency. This finding held even when differences in total spike count across stimuli were normalized, indicating both the primacy and generality of temporal response dynamics in cortical auditory processing. PMID:24598525

  18. Voltage-Controlled Oscillator

    NASA Technical Reports Server (NTRS)

    1995-01-01

    Integrated Component Systems, Inc. incorporated information from a NASA Tech Briefs article into a voltage-controlled oscillator it designed for a customer. The company then applied the technology to its series of phase-locked loop synthesizers, which offer superior phase noise performance.

  19. Characterization CurrentVoltage

    E-print Network

    Luryi, Serge

    Injection Charge of Characterization Current­Voltage Continuation Predictor­Corrector Using or transistor injection charge The 1 which device heterojunction three­terminal a is over field, lateral to ability the Further, heating. carrier for terms multivalued arbitrary, tracing for essential is conditions

  20. Transient Voltage Decoupling Elements

    Microsoft Academic Search

    J. E. Gruber

    1968-01-01

    Premature and inexact timing of thyratron generators may occur during parallel operation of capacitor discharge circuits. Voltage transients which enter the trigger circuits can be eliminated by decoupling spark gaps. A simple, two electrode, spark gap with corona illumination is described. The low jitter of this gap allows its insertion in the output line of a 15 kV thyratron generator

  1. Improved detection of electrical activity with a voltage probe based on a voltage-sensing phosphatase

    PubMed Central

    Tsutsui, Hidekazu; Jinno, Yuka; Tomita, Akiko; Niino, Yusuke; Yamada, Yoshiyuki; Mikoshiba, Katsuhiko; Miyawaki, Atsushi; Okamura, Yasushi

    2013-01-01

    One of the most awaited techniques in modern physiology is the sensitive detection of spatiotemporal electrical activity in a complex network of excitable cells. The use of genetically encoded voltage probes has been expected to enable such analysis. However, in spite of recent progress, existing probes still suffer from low signal amplitude and/or kinetics too slow to detect fast electrical activity. Here, we have developed an improved voltage probe named Mermaid2, which is based on the voltage-sensor domain of the voltage-sensing phosphatase from Ciona intestinalis and Förster energy transfer between a pair of fluorescent proteins. In mammalian cells, Mermaid2 permits ratiometric readouts of fractional changes of more than 50% over a physiologically relevant voltage range with fast kinetics, and it was used to follow a train of action potentials at frequencies of up to 150 Hz. Mermaid2 was also able to detect single action potentials and subthreshold voltage responses in hippocampal neurons in vitro, in addition to cortical electrical activity evoked by sound stimuli in single trials in living mice. PMID:23836686

  2. Development of Automatic Voltage Regulator for Low Voltage Distribution Systems

    NASA Astrophysics Data System (ADS)

    Matsuda, Katsuhiro; Horikoshi, Kazuhiro; Seto, Toshiyuki; Iyama, Osamu; Kobayashi, Hiromu

    This paper presents the development of a new type of voltage regulator that can adequately maintain the voltage supplied to customers, dealing with the problem of voltage control along with the widespread use of photovoltaic power generation systems. The developed equipment is a pole-mounted type voltage regulator consisting of a step-down transformer that converts voltage from high to low and a series transformer for voltage compensation. The demonstration test conducted at the CRIEPI Akagi Test Center confirmed that the voltage control function of the developed voltage regulator is satisfactory based on the proposed control algorism. Also, simulation analysis, on the assumption of the clustered installation of photovoltaic power generation systems, confirmed that the introduction of the developed voltage regulator enables the system voltage to be adequately maintained and full photovoltaic power generation is possible without suppressing the output. It is anticipated that the developed voltage regulator is very effective in adequately regulating the voltage for low voltage distribution systems and gives an effective way for even more widespread photovoltaic power generation.

  3. Voltage collapse proximity index determination using voltage phasors approach

    SciTech Connect

    Gubina, F.; Strmcnik, B. [Univ. of Ljubljana (Slovenia)] [Univ. of Ljubljana (Slovenia)

    1995-05-01

    In the paper, a phasor concept of voltage collapse proximity determination is presented. An adequate voltage proximity index is calculated based on the voltage phasor values only. Furthermore, an algorithm is derived which automatically detects the network transmission paths to the load nodes which are prone to voltage collapse due to additional real or reactive loading. The algorithm is tested on practical networks and exhibits comparable accuracy to the existing methods and low computing time consumption.

  4. BONE MARROW PROGENITOR CELLS REPAIR RAT HEPATIC SINUSOIDAL ENDOTHELIAL CELLS AFTER LIVER INJURY

    PubMed Central

    Harb, Rula; Xie, Guanhua; Lutzko, Carolyn; Guo, Yumei; Wang, Xiangdong; Hill, Colin K.; Kanel, Gary C.; DeLeve, Laurie D.

    2009-01-01

    Background and Aims Damage to hepatic sinusoidal endothelial cells (SEC) initiates sinusoidal obstruction syndrome (SOS), which is most commonly a consequence of myeloablative chemo-irradiation or ingestion of pyrrolizidine alkaloids such as monocrotaline (Mct). This study examines whether SEC are of bone marrow origin, whether bone marrow repair can be a determinant of severity of liver injury and whether treatment with progenitor cells is beneficial. Methods Mct-treated female rats received infusion of male whole bone marrow or CD133+ cells at the peak of sinusoidal injury. The y-chromosome was identified in isolated SEC by fluorescent in situ hybridization. Bone marrow suppression was induced by irradiation of both lower extremities with shielding of the abdomen. Results SEC in uninjured liver have both hematopoietic (CD45, CD33) and endothelial (CD31) markers. After Mct-induced SOS, infusion of bone marrow derived CD133+ progenitor cells replaces more than one-quarter of SEC. All CD133+ cells recovered from the SEC fraction after injury are CD45+. CD133+/45+ progenitors also repaired central vein endothelium. Mct suppresses CD133+/CD45+ progenitors in bone marrow by 50% and in the circulation by 97%. Irradiation-induced bone marrow suppression elicited SOS from a sub-toxic dose of Mct, whereas infusion of bone marrow during the necrotic phase of SOS nearly eradicates histological features of SOS. Conclusions SEC have both hematopoietic and endothelial markers. Bone marrow-derived CD133+/CD45+ progenitors replace SEC and central vein endothelial cells after injury. Toxicity to bone marrow progenitors impairs repair and contributes to the pathogenesis of SOS, whereas timely infusion of bone marrow has therapeutic benefit. PMID:19447108

  5. Pathogenesis of FOLFOX induced sinusoidal obstruction syndrome in a murine chemotherapy model

    PubMed Central

    Robinson, S.M.; Mann, J.; Vasilaki, A.; Mathers, J.; Burt, A.D.; Oakley, F.; White, S.A.; Mann, D.A.

    2013-01-01

    Background & Aims Sinusoidal obstruction syndrome (SOS) following oxaliplatin based chemotherapy can have a significant impact on post-operative outcome following resection of colorectal liver metastases. To date no relevant experimental models of oxaliplatin induced SOS have been described. The aim of this project was to establish a rodent model which could be utilised to investigate mechanisms underlying SOS to aid the development of therapeutic strategies. Methods C57Bl/6 mice, maintained on a purified diet, were treated with intra-peritoneal FOLFOX (n = 10), or vehicle (n = 10), weekly for five weeks and culled one week following final treatment. Sections of the liver and spleen were fixed in formalin and paraffin embedded for histological analysis. The role of oxidative stress on experimental-induced SOS was determined by dietary supplementation with butylated hydroxyanisole and N-acetylcysteine. Results FOLFOX treatment was associated with the development of sinusoidal dilatation and hepatocyte atrophy on H&E stained sections of the liver in keeping with SOS. Immunohistochemistry for p21 demonstrated the presence of replicative senescence within the sinusoidal endothelium. FOLFOX induced endothelial damage leads to a pro-thrombotic state within the liver associated with upregulation of PAI-1 (p <0.001), vWF (p <0.01) and Factor X (p <0.001), which may contribute to the propagation of liver injury. Dietary supplementation with the antioxidant BHA prevented the development of significant SOS. Conclusions We have developed the first reproducible model of chemotherapy induced SOS that reflects the pathogenesis of this disease in patients. It appears that the use of antioxidants alongside oxaliplatin based chemotherapy may be of value in preventing the development of SOS in patients with colorectal liver metastases. PMID:23624001

  6. 3D Hepatic Cultures Simultaneously Maintain Primary Hepatocyte and Liver Sinusoidal Endothelial Cell Phenotypes

    PubMed Central

    Kim, Yeonhee; Rajagopalan, Padmavathy

    2010-01-01

    Developing in vitro engineered hepatic tissues that exhibit stable phenotype is a major challenge in the field of hepatic tissue engineering. However, the rapid dedifferentiation of hepatic parenchymal (hepatocytes) and non-parenchymal (liver sinusoidal endothelial, LSEC) cell types when removed from their natural environment in vivo remains a major obstacle. The primary goal of this study was to demonstrate that hepatic cells cultured in layered architectures could preserve or potentially enhance liver-specific behavior of both cell types. Primary rat hepatocytes and rat LSECs (rLSECs) were cultured in a layered three-dimensional (3D) configuration. The cell layers were separated by a chitosan-hyaluronic acid polyelectrolyte multilayer (PEM), which served to mimic the Space of Disse. Hepatocytes and rLSECs exhibited several key phenotypic characteristics over a twelve day culture period. Immunostaining for the sinusoidal endothelial 1 antibody (SE-1) demonstrated that rLSECs cultured in the 3D hepatic model maintained this unique feature over twelve days. In contrast, rLSECs cultured in monolayers lost their phenotype within three days. The unique stratified structure of the 3D culture resulted in enhanced heterotypic cell-cell interactions, which led to improvements in hepatocyte functions. Albumin production increased three to six fold in the rLSEC-PEM-Hepatocyte cultures. Only rLSEC-PEM-Hepatocyte cultures exhibited increasing CYP1A1/2 and CYP3A activity. Well-defined bile canaliculi were observed only in the rLSEC-PEM-Hepatocyte cultures. Together, these data suggest that rLSEC-PEM-Hepatocyte cultures are highly suitable models to monitor the transformation of toxins in the liver and their transport out of this organ. In summary, these results indicate that the layered rLSEC-PEM-hepatocyte model, which recapitulates key features of hepatic sinusoids, is a potentially powerful medium for obtaining comprehensive knowledge on liver metabolism, detoxification and signaling pathways in vitro. PMID:21103392

  7. Investigation of phase error correction for digital sinusoidal phase-shifting fringe projection profilometry

    NASA Astrophysics Data System (ADS)

    Ma, S.; Quan, C.; Zhu, R.; Tay, C. J.

    2012-08-01

    Digital sinusoidal phase-shifting fringe projection profilometry (DSPFPP) is a powerful tool to reconstruct three-dimensional (3D) surface of diffuse objects. However, a highly accurate profile is often hindered by nonlinear response, color crosstalk and imbalance of a pair of digital projector and CCD/CMOS camera. In this paper, several phase error correction methods, such as Look-Up-Table (LUT) compensation, intensity correction, gamma correction, LUT-based hybrid method and blind phase error suppression for gray and color-encoded DSPFPP are described. Experimental results are also demonstrated to evaluate the effectiveness of each method.

  8. Frequency and Amplitude Tracking of Time-Varying Harmonics and Interharmonics in Power Systems

    Microsoft Academic Search

    Massimo D'Apuzzo; Mauro D'Arco

    2006-01-01

    The paper is focused on monitoring operations performed in power systems. The attention is paid to slow variations characterizing frequency and amplitude parameters of sinusoidal components. A suitable digital signal processing method aimed at estimating frequency and amplitude variations characterizing both the fundamental component as well as single harmonics and interharmonics contained in distorted waveforms is presented. To track time-varying

  9. Dual-frequency cholesteric liquid crystal reflective display

    Microsoft Academic Search

    Ming Xu; Deng Ke Yang

    1999-01-01

    We developed a bistable cholesteric reflective display using a dual frequency cholesteric liquid crystal. When a high frequency voltage is applied to the matrices, it exhibits a negative dielectric anisotropy and is switched to the planar texture which is Bragg reflecting. When a low frequency voltage is applied to the materials, it exhibits a positive dielectric anisotropy and is switched

  10. Electromechanical considerations in developing low-voltage RF MEMS switches

    Microsoft Academic Search

    Dimitrios Peroulis; Sergio P. Pacheco; Kamal Sarabandi; Linda P. B. Katehi

    2003-01-01

    This paper reports on the design, fabrication, and testing of a low-actuation voltage Microelectromechanical systems (MEMS) switch for high-frequency applications. The mechanical design of low spring-constant folded-suspension beams is presented first, and switches using these beams are demonstrated with measured actuation voltages of as low as 6 V. Furthermore, common nonidealities such as residual in-plane and gradient stress, as well

  11. Species differences in sinusoidal and canalicular efflux transport of mycophenolic acid 7-O-glucuronide in sandwich-cultured hepatocytes

    PubMed Central

    Tetsuka, Kazuhiro; Gerst, Nicolas; Tamura, Kouichi; Masters, Jeffrey N

    2014-01-01

    Metabolism and sinusoidal/canalicular efflux of mycophenolic acid (MPA) was investigated using sandwich-cultured hepatocytes (SCHs). After applying MPA to SCHs from humans, wild-type rats, and multidrug resistance-associated protein (Mrp) 2-deficient rats, the MPA metabolites 7-O-glucuronide (MPAG) and acyl glucuronide (AcMPAG) were detected in the intracellular compartment of the SCHs. Sinusoidal efflux of MPAG was detected in all SCH preparations including Mrp2-deficient rat SCHs, whereas canalicular efflux of MPAG was observed in wild-type rat and human SCHs but not in Mrp2-deficient rat SCHs. The ratio of canalicular efflux to net (canalicular plus sinusoidal) efflux was 37 ± 8% in wild-type rat SCHs, while the ratio in human SCHs was significantly lower (20 ± 2%, P < 0.05), indicating species differences in the direction of hepatic MPAG transport. This 20% ratio in human SCHs corresponds to a high sinusoidal MPAG efflux (80%) that can in part account for the urine-dominated recovery of MPAG in humans. Both sinusoidal and canalicular MPAG efflux in rat SCHs shows a good correspondence to urinary and biliary recovery of MPAG after MPA dosing. The sinusoidal efflux of AcMPAG in human SCHs was detected from one out of three donors, suggesting donor-to-donor variation. In conclusion, this study demonstrates the predictive value of SCHs for elucidating the interplay of metabolism and efflux transport, in addition to demonstrating a species difference between rat and human in sinusoidal and canalicular efflux of MPAG. PMID:25505584

  12. High Voltage Seismic Generator

    NASA Astrophysics Data System (ADS)

    Bogacz, Adrian; Pala, Damian; Knafel, Marcin

    2015-04-01

    This contribution describes the preliminary result of annual cooperation of three student research groups from AGH UST in Krakow, Poland. The aim of this cooperation was to develop and construct a high voltage seismic wave generator. Constructed device uses a high-energy electrical discharge to generate seismic wave in ground. This type of device can be applied in several different methods of seismic measurement, but because of its limited power it is mainly dedicated for engineering geophysics. The source operates on a basic physical principles. The energy is stored in capacitor bank, which is charged by two stage low to high voltage converter. Stored energy is then released in very short time through high voltage thyristor in spark gap. The whole appliance is powered from li-ion battery and controlled by ATmega microcontroller. It is possible to construct larger and more powerful device. In this contribution the structure of device with technical specifications is resented. As a part of the investigation the prototype was built and series of experiments conducted. System parameter was measured, on this basis specification of elements for the final device were chosen. First stage of the project was successful. It was possible to efficiently generate seismic waves with constructed device. Then the field test was conducted. Spark gap wasplaced in shallowborehole(0.5 m) filled with salt water. Geophones were placed on the ground in straight line. The comparison of signal registered with hammer source and sparker source was made. The results of the test measurements are presented and discussed. Analysis of the collected data shows that characteristic of generated seismic signal is very promising, thus confirms possibility of practical application of the new high voltage generator. The biggest advantage of presented device after signal characteristics is its size which is 0.5 x 0.25 x 0.2 m and weight approximately 7 kg. This features with small li-ion battery makes constructed device very mobile. The project is still developing.

  13. High voltage pulse conditioning

    DOEpatents

    Springfield, Ray M. (Sante Fe, NM); Wheat, Jr., Robert M. (Los Alamos, NM)

    1990-01-01

    Apparatus for conditioning high voltage pulses from particle accelerators in order to shorten the rise times of the pulses. Flashover switches in the cathode stalk of the transmission line hold off conduction for a determinable period of time, reflecting the early portion of the pulses. Diodes upstream of the switches divert energy into the magnetic and electrostatic storage of the capacitance and inductance inherent to the transmission line until the switches close.

  14. High voltage variable diameter insulator

    DOEpatents

    Vanecek, David L. (Martinez, CA); Pike, Chester D. (Pinole, CA)

    1984-01-01

    A high voltage feedthrough assembly (10) having a tubular insulator (15) extending between the ground plane ring (16) and the high voltage ring (30). The insulator (15) is made of Pyrex and decreases in diameter from the ground plane ring (16) to the high voltage ring (30), producing equipotential lines almost perpendicular to the wall (27) of the insulator (15) to optimize the voltage-holding capability of the feedthrough assembly (10).

  15. Charge-pump voltage converter

    DOEpatents

    Brainard, John P. (Albuquerque, NM); Christenson, Todd R. (Albuquerque, NM)

    2009-11-03

    A charge-pump voltage converter for converting a low voltage provided by a low-voltage source to a higher voltage. Charge is inductively generated on a transfer rotor electrode during its transit past an inductor stator electrode and subsequently transferred by the rotating rotor to a collector stator electrode for storage or use. Repetition of the charge transfer process leads to a build-up of voltage on a charge-receiving device. Connection of multiple charge-pump voltage converters in series can generate higher voltages, and connection of multiple charge-pump voltage converters in parallel can generate higher currents. Microelectromechanical (MEMS) embodiments of this invention provide a small and compact high-voltage (several hundred V) voltage source starting with a few-V initial voltage source. The microscale size of many embodiments of this invention make it ideally suited for MEMS- and other micro-applications where integration of the voltage or charge source in a small package is highly desirable.

  16. High-voltage virtual-cathode microwave simulations

    SciTech Connect

    Thode, L.; Snell, C.M.

    1991-01-01

    In contrast to a conventional microwave tube, a virtual-cathode device operates above the space-charge limit where the depth of the space-charge potential is sufficiently large to cause electron reflection. The region associated with electron reflection is referred to as a virtual cathode. Microwaves can be generated through oscillations in the position of the virtual cathode and by reflexing electrons trapped in the potential well formed between the real and virtual cathodes. A virtual-cathode device based on the first mechanism is a vircator while one based on latter mechanism is a reflex diode. A large number of low-voltage virtual-cathode microwave configurations have been investigated. Initial simulations of a high-voltage virtual-cathode device using a self-consistent particle-in-cell code indicated reasonable conversion efficiency with no frequency chirping. The nonchirping character of the high-voltage virtual-cathode device lead to the interesting possibility of locking four very-high-power microwave devices together using the four transmission lines available at Aurora. Subsequently, in support of two high-voltage experiments, simulations were used to investigate the effect of field-emission threshold and velvet position on the cathode; anode and cathode shape; anode-cathode gap spacing; output waveguide radius; diode voltage; a cathode-coaxial-cavity resonator; a high-frequency ac-voltage drive; anode foil scattering and energy loss; and ion emission on the microwave frequency and power. Microwave

  17. A Novel Modular Bioreactor to In Vitro Study the Hepatic Sinusoid

    PubMed Central

    Illa, Xavi; Vila, Sergi; Yeste, Jose; Peralta, Carmen; Gracia-Sancho, Jordi; Villa, Rosa

    2014-01-01

    We describe a unique, versatile bioreactor consisting of two plates and a modified commercial porous membrane suitable for in vitro analysis of the liver sinusoid. The modular bioreactor allows i) excellent control of the cell seeding process; ii) cell culture under controlled shear stress stimulus, and; iii) individual analysis of each cell type upon completion of the experiment. The advantages of the bioreactor detailed here are derived from the modification of a commercial porous membrane with an elastomeric wall specifically moulded in order to define the cell culture area, to act as a gasket that will fit into the bioreactor, and to provide improved mechanical robustness. The device presented herein has been designed to simulate the in vivo organization of a liver sinusoid and tested by co-culturing endothelial cells (EC) and hepatic stellate cells (HSC). The results show both an optimal morphology of the endothelial cells as well as an improvement in the phenotype of stellate cells, most probably due to paracrine factors released from endothelial cells. This device is proposed as a versatile, easy-to-use co-culture system that can be applied to biomedical research of vascular systems, including the liver. PMID:25375141

  18. The Design of In Vitro Liver Sinusoid Mimics Using Chitosan–Hyaluronic Acid Polyelectrolyte Multilayers

    PubMed Central

    Kim, Yeonhee; Larkin, Adam L.; Davis, Richey M.

    2010-01-01

    Interactions between hepatocytes and liver sinusoidal endothelial cells (LSECs) are essential for the development and maintenance of hepatic phenotypic functions. We report the assembly of three-dimensional liver sinusoidal mimics comprised of primary rat hepatocytes, LSECs, and an intermediate chitosan–hyaluronic acid polyelectrolyte multilayer (PEM). The height of the PEMs ranged from 30 to 55?nm and exhibited a shear modulus of ?100?kPa. Hepatocyte–PEM cellular constructs exhibited stable urea and albumin production over a 7-day period, and these values were either higher or similar to cells cultured in a collagen sandwich. This is of significance because the thickness of a collagen gel is ?1000-fold higher than the height of the chitosan–hyaluronic acid PEM. In the hepatocyte–PEM–LSEC liver-mimetic cellular constructs, LSEC phenotype was maintained, and these cultures exhibited stable urea and albumin production. CYP1A1/2 activity measured over a 7-day period was significantly higher in the hepatocyte–PEM–LSEC constructs than in collagen sandwich cultures. A 16-fold increase in CYP1A1/2 activity was observed for hepatocyte–PEM–10,000 LSEC samples, thereby suggesting that interactions between hepatocytes and LSECs are critical in enhancing the detoxification capability in hepatic cultures in vitro. PMID:20491586

  19. Calibration-free sinusoidal rectification and uniform retinal irradiance in scanning light ophthalmoscopy.

    PubMed

    Yang, Qiang; Yin, Lu; Nozato, Koji; Zhang, Jie; Saito, Kenichi; Merigan, William H; Williams, David R; Rossi, Ethan A

    2015-01-01

    Sinusoidal rectification (i.e., desinusoiding) is necessary for scanning imaging systems and is typically achieved by calculating a rectification transform from a calibration image such as a regular grid. This approach is susceptible to error due to electronic or mechanical instability that can alter the phase of the imaging window with respect to the calibration transform. Here, we show a calibration-free rectification method implemented from live video of a scanning light ophthalmoscope (SLO) with or without adaptive optics (AO). This approach, which capitalizes on positional differences in the images obtained in the forward and backward scan directions, dynamically keeps the imaging window in phase with the motion of the sinusoidal resonant scanner, preventing errors from signal drift over time. A benefit of this approach is that it allows the light power across the field-of-view (FOV) to be modulated inversely to achieve uniform irradiance on the retina, a feature desirable for functional imaging methods and light safety in SLOs. PMID:25531615

  20. Wetting of anisotropic sinusoidal surfaces—experimental and numerical study of directional spreading

    NASA Astrophysics Data System (ADS)

    Fischer, G.; Bigerelle, M.; Kubiak, K. J.; Mathia, T. G.; Khatir, Z.; Anselme, K.

    2014-10-01

    Directional wettability, i.e. the variation of wetting properties, depending on the surface orientation, can be achieved by anisotropic surface texturing. A new high-precision process can produce homogeneous sinusoidal surfaces (in particular, parallel grooves) at the microscale, with a nanoscale residual roughness five orders of magnitude smaller than the texture features. Static wetting experiments have shown that this pattern, even with a very small aspect ratio, can induce a strong variation of the contact angle, depending on the direction of the observation. A comparison with numerical simulations (using Surface Evolver software) shows good agreement and could be used to predict fluid–solid interaction and droplet behaviour on textured surfaces. Two primary mechanisms of directional spreading of water droplets on textured stainless steel surface have been identified. The first one is the mechanical barrier created by the textured surface peaks; this limits spreading in a perpendicular direction to the surface anisotropy. The second one is the capillary action inside of the sinusoidal grooves, which accelerates spreading along the grooves. Spreading has been shown to depend strongly on the history of wetting and internal drop dynamics.

  1. Observation of Recurring Phase-Inversions in Radiatively Heated Single-Mode Sinusoidal Perturbations

    NASA Astrophysics Data System (ADS)

    Lanier, N. E.; Workman, J.; Crockett, S. D.; Holmes, R. L.; Mulford, R. N.; Patterson, B.; Schmidt, D.; Swift, D.; Graham, P.; Moore, A.

    2007-11-01

    Experiments studying the hydrodynamic evolution of radiatively heated single-mode perturbations have been conducted at the OMEGA laser facility. An epoxy layer with a sinusoidal interface is embedded in foam and heated with tin L-shell radiation. As the epoxy expands, an optional shock, with independently controlled strength and timing, is introduced. The resulting hydrodynamic behavior is radiographically. Experimental data along with three-dimensional RAGE simulations are used to generate a more complete picture of this preheat-induced evolution. When preheated, the initial expansion of the sinusoidal perturbation forms a complex set of shocks and an interface that quickly becomes non-linear. The interaction of these preheat-induced shocks result in density gradients, whose phase, with respect to the initial perturbation, oscillates in time. In this experiment, when the shock propagates through the evolving layer, these density gradients are the dominant influence on post-shock hydrodynamic behavior. This work is sponsored by U. S. DOE under Contract No. DE-AC52-06NA25396.

  2. Spatial frequency doubling - Retinal or central. [visual illusion

    NASA Technical Reports Server (NTRS)

    Richards, W.; Felton, T. B.

    1973-01-01

    When a wide field is sinusoidally modulated both in space and in time, the spatial frequency of the pattern will appear doubled at high rates of modulation. Kelly (1966) proposed that this illusion is due to temporal integration of the nonlinear brightness response of the visual system. The anatomical locus of this temporal integrator is uncertain, and could be subcortical. Results indicate that spatial frequency doubling follows binocular disparity detection and is thus a cortical phenomenon.

  3. A voltage-controlled oscillator with an ultra-low supply voltage and its application to a fractional-N phase-locked loop

    Microsoft Academic Search

    Bo Zhao; Xiaojian Mao; Huazhong Yang; Hui Wang

    2009-01-01

    With feature size scaling, the supply voltage of digital circuits is becoming lower and lower. As a result, the supply voltage of analogue and RF circuits must also be reduced for system on chip (SoC) realisation. This article proposes an ultra-low-supply voltage-controlled oscillator (ULSVCO) and designs a sigma–delta fractional-N frequency synthesiser which adopts such ULSVCO. A mathematical phase-noise model is

  4. Excitation of voltage oscillations in an induction voltage adder

    NASA Astrophysics Data System (ADS)

    Bruner, Nichelle; Genoni, Thomas; Madrid, Elizabeth; Welch, Dale; Hahn, Kelly; Oliver, Bryan

    2009-07-01

    The induction voltage adder is an accelerator architecture used in recent designs of pulsed-power driven x-ray radiographic systems such as Sandia National Laboratories’ Radiographic Integrated Test Stand (RITS), the Atomic Weapons Establishment’s planned Hydrus Facility, and the Naval Research Laboratory’s Mercury. Each of these designs relies on magnetic insulation to prevent electron loss across the anode-cathode gap in the vicinity of the adder as well as in the coaxial transmission line. Particle-in-cell simulations of the RITS adder and transmission line show that, as magnetic insulation is being established during a pulse, some electron loss occurs across the gap. Sufficient delay in the cavity pulse timings provides an opportunity for high-momentum electrons to deeply penetrate the cavities of the adder cells where they can excite radio-frequency resonances. These oscillations may be amplified in subsequent gaps, resulting in oscillations in the output power. The specific modes supported by the RITS-6 accelerator and details of the mechanism by which they are excited are presented in this paper.

  5. Constant boost control of the Z-source inverter to minimize current ripple and voltage stress

    Microsoft Academic Search

    Miaosen Shen; Jin Wang; Alan Joseph; Fang Zheng Peng; Leon M. Tolbert; Donald J. Adams

    2006-01-01

    This paper proposes two constant boost-control methods for the Z-source inverter, which can obtain maximum voltage gain at any given modulation index without producing any low-frequency ripple that is related to the output frequency and minimize the voltage stress at the same time. Thus, the Z-network requirement will be independent of the output frequency and determined only by the switching

  6. Electronic voltage and current transformers testing device.

    PubMed

    Pan, Feng; Chen, Ruimin; Xiao, Yong; Sun, Weiming

    2012-01-01

    A method for testing electronic instrument transformers is described, including electronic voltage and current transformers (EVTs, ECTs) with both analog and digital outputs. A testing device prototype is developed. It is based on digital signal processing of the signals that are measured at the secondary outputs of the tested transformer and the reference transformer when the same excitation signal is fed to their primaries. The test that estimates the performance of the prototype has been carried out at the National Centre for High Voltage Measurement and the prototype is approved for testing transformers with precision class up to 0.2 at the industrial frequency (50 Hz or 60 Hz). The device is suitable for on-site testing due to its high accuracy, simple structure and low-cost hardware. PMID:22368510

  7. Voltage-dependent ferromagnetic resonance in epitaxial multiferroic nanocomposites

    NASA Astrophysics Data System (ADS)

    Benatmane, Nadjib; Crane, S. P.; Zavaliche, F.; Ramesh, R.; Clinton, T. W.

    2010-02-01

    We demonstrate electrical control of the ferromagnetic resonance (FMR) in multiferroic nanostructures. A series of heteroepitaxial BiFeO3-NiFe2O4 nanocomposites of varying thickness are characterized using a microwave probe with magnetic and electric sensitivity. We apply an electric field to a sample and observe voltage-driven shifts in the FMR frequency, reflecting a change in magnetic anisotropy. The voltage dependence of the FMR linewidths is even more pronounced, indicating the electric polarization can induce relatively large magnetic nonuniformity in the material. These characteristics may lead to a class of rf filters where both frequency and bandwidth are electrically tunable.

  8. Voltage induction of interfacial Dzyaloshinskii–Moriya interaction in Au/Fe/MgO artificial multilayer

    NASA Astrophysics Data System (ADS)

    Nawaoka, Kohei; Miwa, Shinji; Shiota, Yoichi; Mizuochi, Norikazu; Suzuki, Yoshishige

    2015-06-01

    The Dzyaloshinskii–Moriya interaction (DMI) is an antisymmetric exchange interaction that plays a decisive role in the formation of chiral magnetic structures and in the determination of magnetoelectric properties. This study investigated the impact of an external voltage on the magneto-static surface waves in a Au/Fe/MgO multilayer. Spin waves were excited and detected using two coplanar waveguides and controlled by an external DC voltage. The DC bias voltage dependence of the resonant frequency in the spin waves revealed that the voltage effect has both directionally symmetric and asymmetric components, signifying voltage control of both interfacial magnetic anisotropy and interface-DMI.

  9. Age-related loss of responsiveness to 2,5-dimethoxy-4-iodoamphetamine in liver sinusoidal endothelial cells.

    PubMed

    Cogger, Victoria C; Mitchell, Sarah J; Warren, Alessandra; de Cabo, Rafael; Le Couteur, David G

    2014-05-01

    Age-related pseudocapillarization of the liver sinusoidal endothelium is associated with impaired lipid and drug metabolism and the development of disease. 2,5-Dimethoxy-4-iodoamphetamine is a serotonin receptor 2 agonist that has been shown to have beneficial effects on the liver sinusoidal endothelium in the setting of partial hepatectomy. Here, we have assessed whether 2,5-dimethoxy-4-iodoamphetamine influences ultrastructure of the sinusoidal endothelium in normal 7- and 24-month-old C57Bl6 mice. Following 48 hours of 2,5-dimethoxy-4-iodoamphetamine administration, we found that the liver endothelium in the young, but not in the old, mice had increased porosity compared with controls. This effect appeared to be modulated by increased fenestration size rather than a change in fenestration number. 2,5-Dimethoxy-4-iodoamphetamine is a useful manipulator of fenestration size in the young liver and could be harnessed in the search for therapeutic interventions for pseudocapillarization. PMID:23974079

  10. A Self-Learning Solution for Torque Ripple Reduction for Non-Sinusoidal Permanent Magnet

    E-print Network

    of these currents via a voltage source inverter. Simulation and experimental results from a laboratory prototype and the stator teeth even if there is no current in the stator. Another source of torque pulsation results from

  11. A CMOS integrated linear voltage-to-pulse-delay-time converter for time based analog-to-digital converters

    Microsoft Academic Search

    Holly Pekau; A. Yousif; James W. Haslett

    2006-01-01

    A novel 0.13mum CMOS integrated linear voltage to pulse delay time converter (VTC) is proposed. The VTC architecture uses current starved inverters where the inverter delay versus input voltage characteristic is linearized by using several parallel current starving devices with different gate bias voltages and different amounts of source degeneration. The VTC operates at a clock frequency of up to

  12. Multilevel conversion: high voltage choppers and voltage-source inverters

    Microsoft Academic Search

    T. A. Meynard; H. Foch

    1992-01-01

    The authors discuss high-voltage power conversion. Conventional series connection and three-level voltage source inverter techniques are reviewed and compared. A novel versatile multilevel commutation cell is introduced: it is shown that this topology is safer and more simple to control, and delivers purer output waveforms. The authors show how this technique can be applied to either choppers or voltage-source inverters

  13. Note: Improving low-light-level image detection sensitivity with higher speed using auxiliary sinusoidal light signal

    NASA Astrophysics Data System (ADS)

    Tang, Hongying; Yu, Zhengtao

    2015-06-01

    An improved active imaging method, which upgraded the detection sensitivity by applying an auxiliary sawtooth wave light signal, was reported. Nevertheless, such method sacrificed the imaging speed. To speed up imaging, a sinusoidal light signal is used instead and superposed with the undetectable low-light-level signal on the image sensor. After acquiring a superimposed image set in one sine wave cycle, an unbiased low-light-level image estimation is obtained by using least-square optimization. Through probabilistic analysis and experimental study, we demonstrate that the sinusoidal signal could improve the detection sensitivity 1/3 faster than the sawtooth wave signal.

  14. Sinusoidal reaction formulation for radiation and scattering from conducting surfaces. [of rectangular plates and corner-reflector antennas

    NASA Technical Reports Server (NTRS)

    Wang, N. N.; Richmond, J. H.; Gilreath, M. C.

    1975-01-01

    A piecewise-sinusoidal reaction technique is proposed for the study of scattering and radiation from perfectly conducting bodies of arbitrary shape. The reaction technique described is a moment method based on the integral equation of an electric field. A theory of sinusoidal reaction formulation for radiation and scattering problems is outlined, in which the scattered field is obtained by integrating the surface currents. Numerical results are presented for the scattering patterns of rectangular plates and corner reflectors and the radiation patterns of corner-reflector antennas.

  15. Feasibility of breast cancer lesion detection using a multi-frequency trans-admittance scanner (TAS) with 10 Hz to 500 kHz bandwidth.

    PubMed

    Oh, Tong In; Lee, Jeehyun; Seo, Jin Keun; Kim, Sung Wan; Woo, Eung Je

    2007-07-01

    We describe a new multi-frequency technique for breast cancer detection. Applying a constant voltage with multiple sinusoidal frequencies between a reference electrode on a distal part of a patient and a scan probe placed on the breast, we measure exit currents from an array of electrodes inside the probe that are kept at the ground potential. The distribution of measured exit currents is called the trans-admittance map and the instrument is called the trans-admittance scanner (TAS). We assume a three-dimensional homogeneous domain including an internal lesion with a complex conductivity different from that of the background. Mathematically analyzing the multi-frequency trans-admittance map obtained on the surface of the domain, we found that both conductivity and permittivity ratios between the background and the lesion are crucial in extracting any useful information about the lesion from the map. Choosing two frequencies in the range of 10 Hz to 500 kHz with one significantly lower than the other and assuming that conductivity values of the background and the lesion do not change much from the low to high frequency, the lesion underneath the probe can be detected only when the conductivity ratio between the background and the lesion is different from the permittivity ratio between the background and the lesion at the chosen high frequency. Results of numerical simulations and saline phantom experiments using a developed TAS system are well matched with the mathematical analysis. The biggest advantage of this multi-frequency technique is that we do not need separately measured reference data in the absence of any lesion. We suggest future studies of a more sophisticated lesion detection algorithm based on the analysis and findings described in this paper. PMID:17664649

  16. Real-time detection of musical onsets with linear prediction and sinusoidal modeling

    NASA Astrophysics Data System (ADS)

    Glover, John; Lazzarini, Victor; Timoney, Joseph

    2011-12-01

    Real-time musical note onset detection plays a vital role in many audio analysis processes, such as score following, beat detection and various sound synthesis by analysis methods. This article provides a review of some of the most commonly used techniques for real-time onset detection. We suggest ways to improve these techniques by incorporating linear prediction as well as presenting a novel algorithm for real-time onset detection using sinusoidal modelling. We provide comprehensive results for both the detection accuracy and the computational performance of all of the described techniques, evaluated using Modal, our new open source library for musical onset detection, which comes with a free database of samples with hand-labelled note onsets.

  17. Mathieu function solutions for photoacoustic waves in sinusoidal one-dimensional structures

    NASA Astrophysics Data System (ADS)

    Wu, Binbin; Diebold, Gerald J.

    2012-07-01

    The photoacoustic effect for a one-dimensional structure, the sound speed of which varies sinusoidally in space, is shown to be governed by an inhomogeneous Mathieu equation with the forcing term dependent on the spatial and temporal properties of the exciting optical radiation. New orthogonality relations, traveling wave Mathieu functions, and solutions to the inhomogeneous Mathieu equation are found, which are used to determine the character of photoacoustic waves in infinite and finite length phononic structures. Floquet solutions to the Mathieu equation give the positions of the band gaps, the damping of the acoustic waves within the band gaps, and the dispersion relation for photoacoustic waves. The solutions to the Mathieu equation give the photoacoustic response of the structure, show the space equivalent of subharmonic generation and acoustic confinement when waves are excited within band gaps.

  18. Dynamical states, stochastic resonance, and ratchet effect in a biharmonically driven sinusoidal potential

    NASA Astrophysics Data System (ADS)

    Reenbohn, W. L.; Mahato, Mangal C.

    2015-05-01

    Two stable dynamical states of trajectories of an underdamped particle, under appropriate conditions, appear naturally in a sinusoidal potential when driven by a low-amplitude biharmonic external field. These states are quite stable at low temperatures but make transitions between them as the temperature is raised. The proper choice of the biharmonic drive makes it possible for the system to show, at the same time, both the phenomena of stochastic resonance and the ratchet effect. The ratchet effect, in this case a consequence of the biharmonic drive, is obtained over a large domain of parameter space. However, stochastic resonance can be obtained only over a restricted (sub)domain of parameter space, and it owes its existence largely to the existence of the two dynamical states.

  19. Optimal sliding mode control for linear time-delay systems with sinusoidal disturbances

    NASA Astrophysics Data System (ADS)

    Tang, Gong-You; Lu, Shan-Shan; Dong, Rui

    2007-07-01

    This paper develops a successive approximation approach (SAA) of optimal sliding mode control (SMC) for linear time-delay systems with sinusoidal disturbances. A sequence of two-point boundary value (TPBV) problems with both time-delay and time-advance terms is derived from the optimal sliding mode design. According to the SAA, the original TPBV problems are transformed into a sequence of linear TPBV problems without delay and advance terms. The obtained SMC ensures that the state trajectories reach the sliding surface in finite time and remain on it thereafter. The stability of the sliding mode is proved. A numerical simulation is employed to verify the effectiveness of the proposed approach.

  20. Identical phase oscillators with global sinusoidal coupling evolve by Mobius group action.

    PubMed

    Marvel, Seth A; Mirollo, Renato E; Strogatz, Steven H

    2009-12-01

    Systems of N identical phase oscillators with global sinusoidal coupling are known to display low-dimensional dynamics. Although this phenomenon was first observed about 20 years ago, its underlying cause has remained a puzzle. Here we expose the structure working behind the scenes of these systems by proving that the governing equations are generated by the action of the Mobius group, a three-parameter subgroup of fractional linear transformations that map the unit disk to itself. When there are no auxiliary state variables, the group action partitions the N-dimensional state space into three-dimensional invariant manifolds (the group orbits). The N-3 constants of motion associated with this foliation are the N-3 functionally independent cross ratios of the oscillator phases. No further reduction is possible, in general; numerical experiments on models of Josephson junction arrays suggest that the invariant manifolds often contain three-dimensional regions of neutrally stable chaos. PMID:20059200