Note: This page contains sample records for the topic frequency sinusoidal voltage from Science.gov.
While these samples are representative of the content of Science.gov,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of Science.gov
to obtain the most current and comprehensive results.
Last update: November 12, 2013.
1

A soft commutation constant high frequency link DC\\/AC converter operating with sinusoidal output voltage  

Microsoft Academic Search

The purpose of this paper is to introduce and analyze a high frequency link DC-AC converter for small power UPS applications, with the following properties: operation at constant frequency, soft commutation, isolation by a high frequency transformer, bi-directional power flow capability, absorption of the parasitic elements in the commutation process, simple control circuitry, no need to detect the semiconductor conduction

D. L. R. Vidor; A. J. Perin

1994-01-01

2

Experimental investigation of dielectric barrier discharge plasma actuators driven by repetitive high-voltage nanosecond pulses with dc or low frequency sinusoidal bias  

SciTech Connect

Experimental studies were conducted of a flow induced in an initially quiescent room air by a single asymmetric dielectric barrier discharge driven by voltage waveforms consisting of repetitive nanosecond high-voltage pulses superimposed on dc or alternating sinusoidal or square-wave bias voltage. To characterize the pulses and to optimize their matching to the plasma, a numerical code for short pulse calculations with an arbitrary impedance load was developed. A new approach for nonintrusive diagnostics of plasma actuator induced flows in quiescent gas was proposed, consisting of three elements coupled together: the schlieren technique, burst mode of plasma actuator operation, and two-dimensional numerical fluid modeling. The force and heating rate calculated by a plasma model was used as an input to two-dimensional viscous flow solver to predict the time-dependent dielectric barrier discharge induced flow field. This approach allowed us to restore the entire two-dimensional unsteady plasma induced flow pattern as well as characteristics of the plasma induced force. Both the experiments and computations showed the same vortex flow structures induced by the actuator. Parametric studies of the vortices at different bias voltages, pulse polarities, peak pulse voltages, and pulse repetition rates were conducted experimentally. The significance of charge buildup on the dielectric surface was demonstrated. The charge buildup decreases the effective electric field in the plasma and reduces the plasma actuator performance. The accumulated surface charge can be removed by switching the bias polarity, which leads to a newly proposed voltage waveform consisting of high-voltage nanosecond repetitive pulses superimposed on a high-voltage low frequency sinusoidal voltage. Advantages of the new voltage waveform were demonstrated experimentally.

Opaits, Dmitry F.; Likhanskii, Alexandre V.; Neretti, Gabriele; Zaidi, Sohail; Shneider, Mikhail N.; Miles, Richard B. [Mechanical and Aerospace Engineering, Princeton University, Princeton, New Jersey 08544 (United States); Macheret, Sergey O. [Lockheed Martin Aeronautics Company, Palmdale, California 93599 (United States)

2008-08-15

3

Event synchronous sinusoidal model based on frequency-to-instantaneous frequency mapping  

Microsoft Academic Search

We describe a glottal event synchronous sinusoidal model for speech analysis and synthesis. The sinusoidal components are event synchronously estimated using a mapping from linearly spaced filter center frequencies to the instantaneous frequencies of the filter outputs. Frequency domain fixed points of this mapping correspond to the constituent sinusoidal components of the input signal. A robust technique based on a

Parham Zolfaghari; Hideki Banno; Fumitada Itakura; Hideki Kawahara

2002-01-01

4

A light weight, four quadrant, high switching frequency modular, photovoltaic DC\\/AC inverter, with sinusoidal output and high efficiency  

Microsoft Academic Search

A DC\\/AC power inverter is described for use in stand-alone photovoltaic systems, based on the high-frequency sinusoidal pulse-width modulation principle. The switching frequency is 25 kHz, the nominal battery voltage is 48 V, the output voltage is purely sinusoidal 220 V (RMS) 50 Hz, and the rated power is 1.5 kW. The inverter is modular and has an efficiency of

S. A. Pressas; V. Makios

1988-01-01

5

A modified prony algorithm for estimating sinusoidal frequencies  

Microsoft Academic Search

We investigate the modified Prony algorithm of Osborne and Smyth (1991, 1993) applied to the estimation of the frequency of oscillation of a sinusoidal signal with added white noise, and compare it with the algorithms usually associated with the names of Prony and Pisarenko. We show that the Pisarenko algorithm returns O(N ) consistent estimates, and that the modified Prony

M. S. Mackisack; M. R. Osborne; G. K. Smyth

1994-01-01

6

Comparative analysis of fixed and sinusoidal band hysteresis current controllers for voltage source inverters  

Microsoft Academic Search

A hysteresis controller with a sinusoidal band for current regulation is described. The behavior of the conventional fixed-band controller and the proposed sinusoidal band controller has been thoroughly studied. Simulation results demonstrate that with no lockout (permitting a very high switching frequency) the current waveform can be confined within the desired hysteresis bands. At low lockout frequencies the current is

Ajay Tripathi; Paresh C. Sen

1992-01-01

7

Voltage-Doubler Rectifier with Sinusoidal Input Current Using Pump Circuits  

NASA Astrophysics Data System (ADS)

A single-phase voltage-doubler rectifier using pump circuits is presented. This can be operated in the switching states for pumping action to pump twice the peak supply voltage onto the output capacitor and for forcing the input current to follow its sinusoidal reference in the vicinity of a zero crossing of the supply. The arrangement tested, using two dual-switch power modules with IGBTs and a controller for output voltage regulation, is implemented to investigate the operation. The experimental results confirm that the input current can be waveshaped sinusoidally with a near-unity power factor under the output voltage duplication.

Kiyotake, Hirofumi; Okada, Hidehiko; Ishizaka, Kouichi; Itoh, Ryozo

8

Estimation Characteristics of Input Voltage Waveform of Single-Phase PFC Converter for Both Sinusoidal and Rectangular Input Voltages  

NASA Astrophysics Data System (ADS)

The distribution system with the rectangular voltage waveform is useful for the electrical equipment with the dc voltage source because the high input power factor is obtained by using the diode rectifier circuits. This paper presents a single-phase type AC/DC converter using a novel power factor correction (PFC) technique to realize the unity effective power factor and stable output dc voltage for both the distribution systems with sinusoidal or rectangular voltage waveform. Also, this paper presents the estimation and judgment of the input voltage waveform and its stability and the design of the estimation gains. The new control strategy has a notable advantage that it is flexible for both sinusoidal and rectangular waveforms to realize the good characteristics. The effectiveness of the proposed control scheme has been verified by experiments.

Fukuoka, Hiroatsu; Li, Quan; Kouno, Toshiyuki; Takeshita, Takaharu

9

Event synchronous sinusoidal model based on frequency-to-instantaneous frequency mapping  

NASA Astrophysics Data System (ADS)

We describe a glottal event synchronous sinusoidal model for speech analysis and synthesis. The sinusoidal components are event synchronously estimated using a mapping from linearly spaced filter center frequencies to the instantaneous frequencies of the filter outputs. Frequency domain fixed points of this mapping correspond to the constituent sinusoidal components of the input signal. A robust technique based on a wavelet representation of this fixed points model is used for fundamental frequency extraction as used in STRAIGHT [Kawahara et al., IEICE (1999)]. The method for event detection and characterization is based on group delay and similar fixed point analysis. This method enables the detection of precise timing and spread of speech events such as vocal fold closure. A trajectory continuation scheme is also applied to the extracted sinusoidal components. The proposed model is capable of high-quality speech synthesis using the overlap-add synthesis method and is also applicable to other sound sources. System evaluation results using spectral distortion measures and mean opinion scores will be reported. A comparison with the fixed frame-rate sinusoidal models will be given.

Zolfaghari, Parham; Banno, Hideki; Itakura, Fumitada; Kawahara, Hideki

2002-05-01

10

Joint time-frequency transform processing for linear and sinusoidal FM coherent ladars  

Microsoft Academic Search

We examine the signal processing of both linear and sinusoidal frequency modulation (FM) coherent ladar returns from resolved and unresolved targets, which are spread in Doppler. The Doppler spread may be due to target spin, tumbling, or vibration as well as to the applied linear or sinusoidal-FM on the transmitted E-field. Monte Carlo realizations of the target surface random phasor

Douglas G. Youmans

2003-01-01

11

High Performance Digitally Synthesized Source for Very Low-Frequency AC Voltage Calibrator  

Microsoft Academic Search

The paper describes a high-performance digitally synthesized source (DSS) designed for low-frequency AC voltage calibrator. The source generates very stable and accurate sinusoidal AC voltage from 1.2 to 12 V in frequency range from a few muHz to 100 kHz.

Marian Kampik

2007-01-01

12

Display Area of Sinusoidal Gratings and Low Spatial Frequency Channels.  

National Technical Information Service (NTIS)

The relation between stimulus size of sine gratings and low spatial frequency channels has been systematically investigated by television technique. Experimental data suggest that the human visual system contains low spatial frequency channels. Variation ...

W. Z. Yu

1985-01-01

13

Determination of Quartz Crystal Resonant Frequency by a Novel Multi-Sinusoidal-Signals Approach  

Microsoft Academic Search

Quartz Crystal Microbalance (QCM) is widely used in many fields such as environmental monitoring, biomedical engineering, etc. The methods now used to measure resonant frequency of a QCM have some limitation on accuracy. So a new method of a signal processing system was proposed here for detecting QCM resonant frequencies, based on a novel approach of multi-sinusoidal signals. The QCM

Kui Han; Yong J. Yuan

2011-01-01

14

Homodyne FMCW radar range resolution effects with sinusoidal nonlinearities in the frequency sweep  

Microsoft Academic Search

This paper presents analysis and simulation results describing the effects on the range resolution of linear frequency modulated continuous wave (FMCW) homodyne radar due to sinusoidal nonlinearities in the frequency sweep. Short range applications such as collision avoidance and missile seekers use homodyne FMCW radar. Good range resolution is important to target-to-clutter contrast and to support target discrimination. In FMCW

S. O. Piper

1995-01-01

15

1 MHz sinusoidal gate driver for Class DE inverter operating with variable load and frequency  

Microsoft Academic Search

The subject of this paper is the refinement of a sinusoidal gate driver (SGD). This driver is devoted to the Class DE inverter as the driver of MOSFETs. The load of the inverter has variable parameters. In order to ensure the optimum mode of operation of the Class DE inverter, its switching frequency and relevant commutation angle are automatically adjusted

Boguslaw Grzesik; Z. Kaczmarczyk; Marcin Kasprzak

2000-01-01

16

Transient Voltage Distribution in Stator Winding of Electrical Machine Fed from a Frequency Converter.  

National Technical Information Service (NTIS)

Standard induction motors are exposed to steep fronted, non-sinusoidal voltages when fed from frequency converters. These wave patterns can be destructive to the insulation. The aim of this work is to describe methods of predicting the magnitude and distr...

B. S. Oyegoke

1997-01-01

17

Joint time-frequency transform processing for linear and sinusoidal FM coherent ladars  

NASA Astrophysics Data System (ADS)

We examine the signal processing of both linear and sinusoidal frequency modulation (FM) coherent ladar returns from resolved and unresolved targets, which are spread in Doppler. The Doppler spread may be due to target spin, tumbling, or vibration as well as to the applied linear or sinusoidal-FM on the transmitted E-field. Monte Carlo realizations of the target surface random phasor reflector elements interact with the incident Efield producing laser speckle, and the speckled returns are analyzed in this study. The speckle signals are processed (1) using several spectrum (periodogram based) estimators, (2) the conventional "spectrogram" approach, and (3) ten joint time-frequency transforms (JTFT). We show that the Born-Jordan JTFT is superior to the other spectral estimators tested here in suppressing local oscillator laser noise and accurately estimating the target"s spectrum for signal processing under speckle target return conditions pertaining to coherent laser radar. A new algorithm which sums particular pixels of the JTFT image is introduced and is shown to be much more robust in low CNR conditions than the JTFT maxima or JTFT centroid processing when utilizing the applied linear or sinusoidal-FM modulation waveform.

Youmans, Douglas G.

2003-09-01

18

A Precision Audio-Frequency Voltage Regulator.  

National Technical Information Service (NTIS)

A source of precisely known alternating voltages is described. The output remains constant to within 0.1% for variation of plus or minus 40% in the input voltage (frequencies between 30 Hz and 4 kHz). The principle of operation is based on negative feedba...

D. Britz J. S. Jackson H. H. Bauer

1969-01-01

19

Masking effects of low-frequency sinusoidal gratings on the detection of contrast modulation in high-frequency carriers  

NASA Astrophysics Data System (ADS)

A modification and extension of Kortum and Geisler's model [Vision Res. 35, 1595 (1995)] of early visual nonlinearities that incorporates an expansive nonlinearity (consistent with neurophysiological findings [Vision Res. 35, 2725 (1995)], a normalization based on a local average retinal illumination, similar to Mach's proposal [F. Ratliff, Mach Bands: Quantitative Studies on Neural Networks in the Retina (Holden-Day, San Francisco, Calif., 1965)], and a subsequent compression suggested by Henning et al. [J. Opt. Soc. Am A 17, 1147 (2000)] captures a range of hitherto unexplained interactions between a sinusoidal grating of low spatial frequency and a contrast-modulated grating 2 octaves higher in spatial frequency.

Henning, G. Bruce

2004-04-01

20

Frequency Acquisition in a Signal with Few Sinusoids Using Effective Fourier Transform  

NASA Astrophysics Data System (ADS)

The evaluation of discrete Fourier transforms (DFT) in a real time is a common problem in various technical areas. Nowadays, research in technology offers more and more powerful tools not only for DFT evaluation, but for many signal processing algorithms as well. However, many applications still need either a faster or cheaper solution. In spite of signal processors, where multiplication is usually a one-cycl-operation, in VLSI design of signal processing algorithm, the number of multiplications is one of the important factors for the effective complexity limit of the algorithms. This paper describes a novel algorithm (Effective Fourier Transform, EFT) for an approximative computation of a DFT without multiplication. The algorithm is based on the generation of a discrete harmonic function. Considering some constraints for the frequency of the signal, an arithmetic shift can be used instead of the multiplication by cos(W). Columns of the DFT- matrix can be approximated by the reorganized samples of the harmonic generator. Considering addition and arithmetic shifts as basic operations, EFT is faster than the classical "butterfly" fast Fourier transform. An error analysis of the algorithm depends on the speed limitation. Several factors, such as the length of the DFT and number of sinusoids in an analyzed spectrum have an effect on the error analysis. Maximum error cca 2 % of the spectral magnitude is guarantied for the worst case. For well- separated sinusoids in the spectrum and for some "magic" lengths of EFT, a maximum error cca 0.1% can be achieved. For statistical evaluation of the spectrum EFT is even more suitable, as one part of the algorithm can be done only once for several EFT computations.

Rozinaj, Gregor

1996-04-01

21

Multi-Level DC Bus Inverter for Providing Sinusoidal and PWM Electrical Machine Voltages.  

National Technical Information Service (NTIS)

A circuit for controlling an ac machine comprises a full bridge network of commutation switches which are connected to supply current for a corresponding voltage phase to the stator windings, a plurality of diodes, each in parallel connection to a respect...

G. J. Su

2003-01-01

22

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

Microsoft Academic Search

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

Atif Iqbal; Emil Levi

2006-01-01

23

Procrastinating voltage scheduling with discrete frequency sets  

Microsoft Academic Search

This paper presents an efficient method to find the opti- mal intra-task voltage\\/frequency scheduling for single tasks in practical real-time systems using statistical workload in- formation. Our method is analytic in nature and proved to be optimal. Simulation results verify our theoretical analy- sis and show significant energy savings over previous meth- ods. In addition, in contrast to the previous

Zhijian Lu; Yan Zhang; Mircea R. Stan; John Lach; Kevin Skadron

2006-01-01

24

Procrastinating voltage scheduling with discrete frequency sets  

Microsoft Academic Search

This paper presents an efficient method to find the optimal intra-task voltage\\/frequency scheduling for single tasks in practical real-time systems using statistical workload information. Our method is analytic in nature and proved to be optimal. Simulation results verify our theoretical analysis and show significant energy savings over previous methods. In addition, in contrast to the previous techniques in which all

Zhijian Lu; Yan Zhang; Mircea Stan; K. Lach; Kevin Skadron

2006-01-01

25

Novel voltage fed high frequency inverter for induction heating with load voltage boost  

Microsoft Academic Search

A voltage-fed high-frequency inverter with load voltage boost for induction heating is analyzed. The inverter circuit works on the principle of natural commutation. The voltage across the load is boosted to about 15 to 20 times that of the input DC voltage. Necessary conditions for the reliable operation of the inverter circuit are derived, and the improvements of the scheme

V. N. Nandakumar; K. Yadukumar; S. Ragupathi; R. K. Hegde; M. Ramamoorty

1992-01-01

26

Necessary and sufficient conditions for frequency entrainment of quasi-sinusoidal injection-synchronized oscillators  

Microsoft Academic Search

A method is presented which permits the first-approximation exact analysis of the dynamical stability of fundamental-mode injectionsynchronized oscillators (FISO's) characterized by a quasi-sinusoidal quasi-static behavior. By combining small parameter and stroboscopic transformation techniques, the phase-lock stability investigation of an nth-order system is reduced to the simple Hurwitz test on an nth degree polynomial easily obtainable from steady state describing quantities.

ENRICO F. CALANDRA; ANTONINO M. SOMMARIVA

1986-01-01

27

Quartz crystal microbalance based on passive frequency to voltage converter  

SciTech Connect

In dynamics of evaporation or drying of microdrops from a solid surface, a faster and precise quartz crystal microbalance (QCM) is needed. The fast QCM based on frequency to voltage converter is an attractive and powerful tool in the investigation of the dynamic regime of evaporation to translate the frequency shift in terms of a continuous voltage change. The frequency shift monitoring in fast QCM applications is a real challenge for electronic processing interface. Originally developed as a frequency shift processing interface, this novel passive frequency to voltage converter can produce faster, stable, and accurate results in regard to the QCM sensor behavior. In this article, the concept and circuit of passive frequency to voltage converter will be explained followed by static and dynamic characterization. Experimental results of microdrops evaporation will be given.

Burda, Ioan; Tunyagi, Arthur [Department of Physics, Babes-Bolyai University, Cluj-Napoca, 400084 (Romania)

2012-02-15

28

Quartz crystal microbalance based on passive frequency to voltage converter  

NASA Astrophysics Data System (ADS)

In dynamics of evaporation or drying of microdrops from a solid surface, a faster and precise quartz crystal microbalance (QCM) is needed. The fast QCM based on frequency to voltage converter is an attractive and powerful tool in the investigation of the dynamic regime of evaporation to translate the frequency shift in terms of a continuous voltage change. The frequency shift monitoring in fast QCM applications is a real challenge for electronic processing interface. Originally developed as a frequency shift processing interface, this novel passive frequency to voltage converter can produce faster, stable, and accurate results in regard to the QCM sensor behavior. In this article, the concept and circuit of passive frequency to voltage converter will be explained followed by static and dynamic characterization. Experimental results of microdrops evaporation will be given.

Burda, Ioan; Tunyagi, Arthur

2012-02-01

29

The Extended Kalman Filter in the Frequency Domain for the Identification of Mechanical Structures Excited by Sinusoidal Multiple Inputs  

NASA Astrophysics Data System (ADS)

A modal parameter identification method applied to mechanical structures excited by correlated sinusoidal multiple inputs was developed. The algorithm is based on the same formulation of the extended Kalman filter, applied as a system parameter identifier in the frequency domain to mechanical structures subject to excitations characterised by an inherently high degree of correlation. The algorithm was validated by using simulated data on a multi-degree-of-freedom system. The tests demonstrate that the proposed technique is of practical application value. The method is devoted to the identification of the modal parameters of supporting structures of rotating machinery, using data obtained during the normal operation of the machines. Nonetheless, it can have an interest for more general applications in the field of the experimental modal analysis. This study was undertaken in the framework of the BRITE EURAM III project MODIAROT (MOdel based DIAgnosis of ROTors in power plants).

Provasi, Riccardo; Zanetta, Gian Antonio; Vania, Andrea

2000-05-01

30

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

NASA Astrophysics Data System (ADS)

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.

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

2009-04-01

31

Sinusoidal Waveform Following Method for Digital Control of PWM inverter  

NASA Astrophysics Data System (ADS)

Fast responses without any steady-state errors are required for control of a sinusoidal PWM inverter. Its reference voltage waveform is not constant but sinusoidal. The output voltage is controlled to coincide with a reference waveform. However the reference varies to be a further value when the output reaches the value. So there is always a deviation between the reference and the output voltages. It is necessary to design a compensator by considering these sinusoidal variations of the reference waveform to get a good steady-state and fast transient response. This paper proposes a sort of digital repetitive control systems for a sinusoidal PWM inverter control. It is based on the internal model principle to realize a response with no deviation for a periodic sinusoidal reference input. It has a simple numerator and a denominator z2-2z cos ?T + 1 of a transfer function which is equal to the z function of a sinusoidal waveform of the angular frequency ? and the sample time T. Compensator and feedback gains of the inverter are determined by the optimal control principle. The proposed method is investigated for actual performances and it is validated through theoretical and experimental results for linear and nonlinear loads by using a DSP system at the switching frequency of 20kHz.

Kato, Toshiji; Inoue, Kaoru; Kuroda, Shinsaku

32

High voltage high frequency power transformer for pulsed power application  

Microsoft Academic Search

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

Todor Filchev; Fabio Carastro; Pat Wheeler; Jon Clare

2010-01-01

33

Instantaneous Frequency Expressions of Sinusoid from Time-Differential Domain Samples  

NASA Astrophysics Data System (ADS)

In this paper, instantaneous frequency expressions are mathematically derived, where each of the expressions is a function of sine-wave samples in time-differential domain space. At first, we introduce differential operator, divided finite difference operator, shifting operator, and mean operator. Then, we derive a strict expression of instantaneous frequency by applying the operators to the governing equation, which generates sine-wave. It is shown that the derived expression is identical to the Prony's method. Next, the other five expressions of instantaneous frequency are derived by the operator-applying method. Numerical results show that precise instantaneous frequencies are calculated by using the expressions. All the expressions are not under constraint of the uncertainty principle, and one of them is not under constraint of the sampling theorem.

Kubo, Kazuyoshi

34

Simultaneous optimization of battery-aware voltage regulator scheduling with dynamic voltage and frequency scaling  

Microsoft Academic Search

Energy-aware task scheduling significantly reduces the total energy required by a system to perform a particular job, by dynamically changing the clock frequency and supply voltage at which the CPU operates. But this causes significant fluctuation of the current drawn from the power source, so that no single voltage regulator can achieve satisfactory efficiency over the entire range of operating

Youngjin Cho; Younghyun Kim; Yongsoo Joo; Kyungsoo Lee; Naehyuck Chang

2008-01-01

35

A Novel Single-Phase Rectifier Circuit to Generate High DC Voltage by LC Resonance in Commercial Frequency  

NASA Astrophysics Data System (ADS)

For small capacity rectifier circuits such as those for consumer electronics and appliances, capacitor input type rectifier circuits are generally used. Consequently, various harmonics generated within the power system become a serious problem. Various studies to improve these effects have been presented so far. However, most of these employ switching devices, such as FETs and the like. The absence of switching devices makes systems more tolerant to over-load, and brings low radio noise benefits. The authors had proposed a power factor correction scheme using a LC resonance in commercial frequency without switching devices. This method makes a sinusoidal wave by widening conduction period using the current resonance in commercial frequency. It is found that the output high voltage can be obtained easily by means of LC resonance in this PFC circuit, whose dc output voltage becomes even ten times ac input voltage and the like. In this paper, the results are reported and confirmed by the theoretical and experimental implementations.

Matsui, Keiju; Yamamoto, Isamu; Erdong, Guan; Hasegawa, Masaru; Ando, Kenji; Ueda, Fukashi; Mori, Hideki

36

BIOLOGICAL INFLUENCES OF LOW-FREQUENCY SINUSOIDAL ELECTROMAGNETIC SIGNALS ALONE AND SUPERIMPOSED ON RF CARRIER WAVES  

EPA Science Inventory

The report describes in a historical context the experiments that have been performed to examine the biological responses caused by exposure to low frequency electromagnetic radiation directly or as modulation of RF carrier waves. A detailed review is provided of the independentl...

37

Frequency, thermal and voltage supercapacitor characterization and modeling  

Microsoft Academic Search

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

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

2007-01-01

38

High-frequency characteristics of high-voltage power line  

Microsoft Academic Search

This paper presents a major high-frequency characteristic of high-voltage overhead power line: amplitude characteristics, group delay and noise characteristics. Since measurements of high-frequency power-line characteristics are rare due to permission of power utilities for access to power lines, computer simulations have a crucial role in design of communication systems via power lines. Simulated high-frequency and noise characteristics of 400 kV

N. Suljanovic; A. Mujcic; M. Zajc; J. F. Tasic

2003-01-01

39

Thermal Effects of High-Frequency Voltage on Medium Voltage Cable Terminations  

Microsoft Academic Search

Field experiences have shown that transmission systems using voltage sourced converters (VSCs) with IGBT's can produce high frequency harmonic resonances in the VSC station environment. Modern cable terminations using non-geometric stress grading can be susceptible to degradation under these harmonics. In this study a setup was designed to test cable terminations under conditions representative of high frequency harmonic resonance in

Sarajit Banerjee; Shesha H. Jayaram

2007-01-01

40

Low-frequency sinusoidal galvanic stimulation of the left and right vestibular nerves reveals two peaks of modulation in muscle sympathetic nerve activity  

Microsoft Academic Search

Studies previously performed in our laboratory have shown that sinusoidal galvanic vestibular stimulation (sGVS), a means\\u000a of selectively modulating vestibular input without affecting other inputs, can cause partial entrainment of muscle sympathetic\\u000a nerve activity (MSNA) at frequencies ranging from 0.2 to 2.0 Hz. Here we test the effect of sGVS on sympathetic outflow when\\u000a stimulating the vestibular system at lower frequencies.

Elie Hammam; Cheree James; Tye Dawood; Vaughan G. Macefield

41

Steady-state response of single-phase and three-phase circuits containing single-phase transformers to sinusoidal or nonsinusoidal voltages. Topical report, December 1982August 1984 (first draft)  

Microsoft Academic Search

A method for calculating the steady-state response of selected circuits which contain single-phase transformers or balanced three-phase banks of single-phase transformers is investigated. The method works for nonsinusoidal applied voltages as well as it does for sinusoidal voltages. The nonlinearity of the transformer iron if accounted for, but impedances external to the transformer are assumed to be linear and time

Fuchs

1985-01-01

42

MODELING HIGH FREQUENCY SIGNAL PROPAGATION OVER LOW VOLTAGE DISTRIBUTION LINES  

Microsoft Academic Search

This paper examines fundamentals of signal propagation over low-voltage (LV) bare conductor power lines. Overhead lines, service cables and loads are modelled using the electromagnetic power system transients program (EMTP) and LV systems are analysed with different load types and magnitudes. It is found that high loads significantly attenuate the high frequency signals on LV lines. A novel technique is

R. Keyhani; D. Birtwhistle

43

A frequency compensation scheme for LDO voltage regulators  

Microsoft Academic Search

A stable low dropout (LDO) voltage regulator topology for low equivalent series resistance (ESR) capacitive loads is presented. The proposed scheme generates a zero internally instead of relying on the zero generated by the load capacitor and its ESR combination for stability. It is demonstrated that this scheme realizes robust frequency compensation, facilitates the use of multilayer ceramic capacitors for

Chaitanya K. Chava; José Silva-Martínez

2004-01-01

44

A High Frequency Voltage-Controlled Phase Shifter.  

National Technical Information Service (NTIS)

A phase-shifter is described with an operating frequency range up to 10 MHz and a linear, voltage-controlled phase-shift range of 360 deg. The design has proved to be reliable, stable, and accurate in operation. (Author)

C. W. Sutton A. J. Farrell

1974-01-01

45

Effects of power frequency voltages on amputated human limb  

PubMed Central

Carter, A. O., and Morley, R. (1969).Brit. J. industr. Med.,26, 224-230. Effects of power frequency voltages on amputated human limb. Electric voltages of between 40 and 500 V at 50 Hz and 120 and 240 V direct were applied to freshly amputated mid-thigh legs connected to a heart-lung machine. Current and voltage were recorded against time. The direct currents showed a rise of current with time and caused little skin damage. The make and break of the current caused contractions of the muscles. The alternating currents produced by voltages between 30 and 80 V showed a steady rise with progressive skin damage. With alternating voltages of 250 and 500 V the current showed a rapid rise, with an equally rapid fall after a period of time. The current wave-form was nonsinusoidal and, after the fall, showed unidirectional impulses. Muscular contraction was tonic but later became clonic due to the impulses of current. This progression has been described in held-on electric shock accidents. Images

Carter, A. O.; Morley, R.

1969-01-01

46

Time dependent behaviors of ion-ion plasmas exposed to various voltage waveforms in the kilohertz to megahertz frequency range  

SciTech Connect

An ion-ion plasma, situated between two parallel electrodes, is studied with the use of a time dependent one-dimensional particle-in-cell Monte-Carlo collisions model. This plasma consists of only positively and negatively singly charged ions with the same order of mass and temperature (the electron density is zero). The right electrode is grounded, and the left electrode is biased with a voltage waveform varying from sinusoidal to square with the frequency in the kHz to MHz range. The sheath evolution and the particle flux towards the electrodes, as a function of both space and time, are investigated for the various waveforms and frequencies. The sheath evolution has a strong influence on the time averaged ion energy distribution function (IEDF). The IEDF is broad with a low energy tail for low frequency sinusoidal biases (25 kHz) while peaked at low energy for higher frequencies (2 MHz). For square waveforms, the IEDF is mono-energetic with some broadening when the rise time is faster than the typical time to establish the steady state sheath formation (<0.3 {mu}s).

Oudini, N.; Raimbault, J.-L.; Chabert, P.; Aanesland, A. [Laboratoire de Physique des Plasmas, CNRS, Ecole Polytechnique, 91128 Palaiseau Cedex (France); Garrigues, L. [LAPLACE (Laboratoire Plasma et Conversion d'Energie), Universite de Toulouse, UPS, INPT Toulouse, 118 route de Narbonne, F-31062 Toulouse cedex 9 (France); CNRS, LAPLACE, F-31062 Toulouse (France); Meige, A. [PRESANS/X-Technologies/Ecole Polytechnique, 91128 Palaiseau Cedex (France)

2012-10-15

47

Time dependent behaviors of ion-ion plasmas exposed to various voltage waveforms in the kilohertz to megahertz frequency range  

NASA Astrophysics Data System (ADS)

An ion-ion plasma, situated between two parallel electrodes, is studied with the use of a time dependent one-dimensional particle-in-cell Monte-Carlo collisions model. This plasma consists of only positively and negatively singly charged ions with the same order of mass and temperature (the electron density is zero). The right electrode is grounded, and the left electrode is biased with a voltage waveform varying from sinusoidal to square with the frequency in the kHz to MHz range. The sheath evolution and the particle flux towards the electrodes, as a function of both space and time, are investigated for the various waveforms and frequencies. The sheath evolution has a strong influence on the time averaged ion energy distribution function (IEDF). The IEDF is broad with a low energy tail for low frequency sinusoidal biases (25 kHz) while peaked at low energy for higher frequencies (2 MHz). For square waveforms, the IEDF is mono-energetic with some broadening when the rise time is faster than the typical time to establish the steady state sheath formation (<0.3 ?s).

Oudini, N.; Garrigues, L.; Meige, A.; Raimbault, J.-L.; Chabert, P.; Aanesland, A.

2012-10-01

48

Aggregation of voltage and frequency dependent electrical loads  

NASA Astrophysics Data System (ADS)

Electrical loads play a very important role in the behaviour of an electric power system. Since there is a tremendous number of different loads in the system, representing each load with its own model becomes impractical for system level studies. This thesis deals with the issue of aggregating loads to simplify system level studies. Six new and accurate aggregate static load models, a novel EMTP based load model, and four very accurate aggregate induction machine models have been developed. The proposed aggregate load models are voltage and frequency dependent and accommodate the different data formats of individual loads. By including the information of voltage and frequency dependence, the models can be used in larger ranges of studies than the conventional aggregate static load models, thus resulting in more accurate representations. The valid voltage range of the models is about 75% to 125% of rated voltage and, the valid range of frequency of the models is about 85% to 115% of rated frequency. The proposed EMTP load model represents a load with basic circuit elements. The model consists of two varied turns ratio transformers and two varied admittance RLC circuits. It represents the voltage dependence and the frequency dependence of a load separately, resulting in a much simpler load representation than a conventional load model. The model not only improves the accuracy of load representations, bus also broadens the EMTP application in studies other than the transient analyses, such as power flow studies. The proposed aggregate induction machine models have been developed based on the specifications and circuit parameters of individual machines. Since the specification of the machines are the most basic information of the devices, they provide a natural and accurate representation of the machines. The circuit parameters of the machines reflect the behaviour of the devices, they can be used to compose the machines under high and low frequencies, resulting in a simple and accurate machine representation. These two different aggregate models accommodate the data availability of individual machines. To verify the validity of the proposed load models, field tests from published literature are compared with computer simulations. The simulation results of some test systems obtained (i) by the proposed load models, (ii) by the conventional load models, and (iii) by solving the original systems without aggregating their circuit components are also compared. The results of these comparisons prove that the proposed load models can represent loads in power systems more accurately than the existing load models. The proposed load models have been developed into computer software packages with the high level computer programming language Ada 95.

Louie, Kwok-Wai

49

Novel Current Mode AC\\/AC Converters with High Frequency AC Link  

Microsoft Academic Search

A novel circuit topologies family of the current mode AC\\/AC converter with high frequency ac link, based on flyback converter, are proposed. These circuit topologies which can transfer one unregulated sinusoidal voltage with high THD into another regulated constant frequency sinusoidal voltage with low THD, are constituted of input cycloconverter, high frequency storage transformer and output cycloconverter. The circuit topologies

Daolian Chen; Lei Li; Jian Liu; Shengyang Lin; Chen Song

2005-01-01

50

Note: Measuring breakdown characteristics during the hot re-ignition of high intensity discharge lamps using high frequency alternating current voltage  

NASA Astrophysics Data System (ADS)

To investigate the cold and hot re-ignition properties of High Intensity Discharge (HID) lamps in more detail an automated setup was designed in such a way that HID lamps of various sizes and under different background pressures can be tested. The HID lamps are ignited with a ramped sinusoidal voltage signal with frequencies between 60 and 220 kHz and with amplitude up to 7.5 kV. Some initial results of voltage and current measurements on a commercially available HID lamp during hot and cold re-ignition are presented.

van den Bos, R. A. J. M.; Sobota, A.; Manders, F.; Kroesen, G. M. W.

2013-04-01

51

Analytical and computational investigations of airfoils undergoing high-frequency sinusoidal pitch and plunge motions at low Reynolds numbers  

NASA Astrophysics Data System (ADS)

Current interests in Micro Air Vehicle (MAV) technologies call for the development of aerodynamic-design tools that will aid in the design of more efficient platforms that will also have adequate stability and control for flight in gusty environments. Influenced largely by nature MAVs tend to be very small, have low flight speeds, and utilize flapping motions for propulsion. For these reasons the focus is, specifically, on high-frequency motions at low Reynolds numbers. Toward the goal of developing design tools, it is of interest to explore the use of elementary flow solutions for simple motions such as pitch and plunge oscillations to predict aerodynamic performance for more complex motions. In the early part of this research, a validation effort was undertaken. Computations from the current effort were compared with experiments conducted in a parallel, collaborative effort at the Air Force Research Laboratory (AFRL). A set of pure-pitch and pure-plunge sinusoidal oscillations of the SD7003 airfoil were examined. Phase-averaged measurements using particle image velocimetry in a water tunnel were compared with computations using two flow solvers: (i) an incompressible Navier-Stokes Immersed Boundary Method and (ii) an unsteady compressible Reynolds-Averaged Navier-Stokes (RANS) solver. The motions were at a reduced frequency of k = 3.93, and pitch-angle amplitudes were chosen such that a kinematic equivalence in amplitudes of effective angle of attack (from plunge) was obtained. Plunge cases showed good qualitative agreement between computation and experiment, but in the pitch cases, the wake vorticity in the experiment was substantially different from that predicted by both computations. Further, equivalence between the pure-pitch and pure-plunge motions was not attained through matching effective angle of attack. With the failure of pitch/plunge equivalence using equivalent amplitudes of effective angle of attack, the effort shifted to include pitch-rate and wake-effect terms through the use of analytical methods including quasi-steady thin-airfoil theory (QSTAT) and Theodorsen's theory. These theories were used to develop three analytical approaches for determining pitch motions equivalent to plunge motions. A study of variation in plunge height was then examined and followed by a study of the effect of rotation point using the RANS solver. For the range of plunge heights studied, it was observed that kinematic matching between plunge and pitch using QSTAT gave outstanding similarities in flow field, while the matching performed using Theodorsen's theory gave the best equivalence in lift coefficients for all cases. The variation of rotation point revealed that, for the given plunge height, with rotation point in front of the mid-chord location, all three schemes matched flow-field vorticity well, and with rotation point aft of the mid-chord no scheme matched vorticity fields. However, for all rotation points (except for the mid-chord location), CFD prediction of lift coefficients from the Theodorsen matching scheme matched the lift time histories closely to CFD predictions for pure-pitch. Combined pitch and plunge motions were then examined using kinematic parameters obtained from the three schemes. The results showed that QSTAT nearly cancels the vortices emanating from the trailing edge. Theodorsen's matching approach was successful in generating a lift that was close to constant over the entire cycle. Additionally this approach showed the presence of the reverse Karman vortex sheet through the wake. Combined pitch/plunge motions were then analyzed, computationally and experimentally, with a non-zero mean angle of attack. All computational results compared excellently with experiments, capturing vorticity production on the airfoil's surface and through the wake. Lift coefficient through a cycle was shown to tend toward a constant using Theodorsen's parameters, with the constant being dependent on the initial angle of attack. This result points to the possibility of designing an unsteady motion to match a given flig

McGowan, Gregory Z.

52

Dual signal frequencies and voltage levels for low power and temperature-gradient tolerant clock distribution  

Microsoft Academic Search

A methodology based on supply voltage and frequency scaling for lowering the power consumption and temperature fluctuations induced skew of clock distribution networks is proposed in this paper. The clock signal is distributed globally at a scaled supply voltage and frequency. The optimum supply voltage that minimizes clock skew is 44% less than the nominal supply voltage in a 0.18?m

Sherif A. Tawfik; Volkan Kursun

2007-01-01

53

A pulse width modulation technique for a multilevel converter in high voltage high frequency applications  

Microsoft Academic Search

In this paper, a new hysteresis voltage control technique based on optimized harmonic elimination method is presented for a single phase multilevel inverter with flying capacitor topology in high voltage high frequency applications such as high voltage plasma systems. A main objective of the proposed technique is to generate high voltage and control capacitors voltages in all operational conditions. For

Jafar Adabi; Hamid Soltani; Firuz Zare

2008-01-01

54

Photonic millimeter-wave generation from frequency-multiplied Erbium-doped fiber laser pulse-train using purely sinusoidal-wave modulated laser diode  

NASA Astrophysics Data System (ADS)

Photonic millimeter-wave generation from high-order frequencymultiplied optical pulse-train of Erbium-doped fiber laser (EDFL) harmonic mode-locked at repetition frequency of 1 GHz is demonstrated. A Fabry-Perot laser diode (FPLD) operated at below threshold condition is employed as an intra-cavity optical mode-locker, which is purely sinusoidal-wavemodulated at 1 GHz without any DC biased current in this experiment. The threshold modulating power of 18 dBm for the FPLD is observed for harmonic mode-locking the EDFL. The frequency-multiplication of EDFL pulse-train is implemented by detuning the modulating frequency of the FPLD. At highest repetition rate of 42 GHz, the peak power and pulseswidth of frequency-multiplied EDFL pulse-train are 140 mW and 2.7 ps, respectively.

Lin, Gong-Ru; Wu, Jung-Rung; Chang, Yung-Cheng

2004-08-01

55

Photonic millimeter-wave generation from frequency-multiplied Erbium-doped fiber laser pulse-train using purely sinusoidal-wave modulated laser diode.  

PubMed

Photonic millimeter-wave generation from high-order frequencymultiplied optical pulse-train of Erbium-doped fiber laser (EDFL) harmonic mode-locked at repetition frequency of 1 GHz is demonstrated. A Fabry-Perot laser diode (FPLD) operated at below threshold condition is employed as an intra-cavity optical mode-locker, which is purely sinusoidal-wavemodulated at 1 GHz without any DC biased current in this experiment. The threshold modulating power of 18 dBm for the FPLD is observed for harmonic mode-locking the EDFL. The frequency-multiplication of EDFL pulse-train is implemented by detuning the modulating frequency of the FPLD. At highest repetition rate of 42 GHz, the peak power and pulseswidth of frequency-multiplied EDFL pulse-train are 140 mW and 2.7 ps, respectively. PMID:19483960

Lin, Gong-Ru; Wu, Jung-Rung; Chang, Yung-Cheng

2004-08-23

56

Voltage and Frequency Control of Isolated Asynchronous Generator with Reduced Switch Integrated Voltage Source Converter in Isolated Wind Power Generation  

Microsoft Academic Search

This paper deals with the I.cosż algorithm for the voltage and frequency control (VFC) of an autonomous wind power generation using an isolated asynchronous generator (IAG) feeding three-phase four-wire loads. The reference source currents are estimated using the I.cosż algorithm to control the voltage and frequency of IAG system. Two-leg voltage source converter (VSC) with split capacitor and an isolated

Shailendra Sharma; Bhim Singh

2009-01-01

57

Voltage and frequency control with reduced switch integrated voltage source converter for IAG in wind energy conversion system  

Microsoft Academic Search

This paper deals with a voltage and frequency controller (VFC) of a stand-alone wind energy conversion system using an isolated asynchronous generator (IAG) feeding three-phase four-wire loads. The reference generator currents are estimated using the power balance theory to control the voltage and frequency of IAG system. Two-leg reduced switch integrated voltage source converter (VSC) with a battery energy storage

Bhim Singh; Shailendra Sharma; Ambrish Chandra; K. Al Haddad

2010-01-01

58

Comparison between Ramp Pulse Modulation (RPM) and constant frequency modulation for the beat frequency oscillation in voltage regulators  

Microsoft Academic Search

In the voltage regulator (VR) applications, the load frequency varies in a very wide range from several kHz to several MHz. When the load transient frequency approaches to the switching frequency of VR, there is a low frequency oscillation in the system, which is the beat frequency oscillation between the load transient frequency and the switching frequency of VR. When

Kisun Lee; Han Zou

2010-01-01

59

Testing of insulating materials at high frequencies and high voltage based on the tesla transformer principle  

Microsoft Academic Search

Insulation materials used in high-voltage switched-mode power supplies are exposed to high-frequent high voltages. Ageing tests performed with high DC voltages or low-frequency high voltages might not reveal the true ageing effects which take place during rated operation at high frequency. Studies on different voltage source principles have been carried out. Finally the tesla transformer principle turned out to be

N. Hardt; D. Koenig

1998-01-01

60

Power Balance Theory Based Voltage and Frequency Control for IAG in Wind Power Generation  

Microsoft Academic Search

This paper deals with an application of the power balance theory in a voltage and frequency controller (VFC) of an autonomous wind power generation using an isolated asynchronous generator (IAG) feeding three-phase four wire loads. The reference generator currents are estimated using the power balance theory to control the voltage and frequency of IAG system. Three-leg voltage source converter (VSC)

Bhim Singh; Shailendra Sharma

2009-01-01

61

A Survey of Frequency and Voltage Control Ancillary Services—Part I: Technical Features  

Microsoft Academic Search

This two-part paper surveys the frequency and voltage control ancillary services in power systems from various parts of the world. In this first part, the nomenclature used to describe active power reserves across 11 systems is first reviewed in order to facilitate the comparison of frequency control ancillary services. The essential technical features of frequency and voltage control ancillary services

Yann G. Rebours; Daniel S. Kirschen; Marc Trotignon; Sébastien Rossignol

2007-01-01

62

A software for simulation and controller development for high frequency high voltage power supplies  

Microsoft Academic Search

This paper describes software developed for the simulation of high voltage (up to 125 kV), high frequency power supply for radiology equipment. The main components of the power supply are an AC-DC conversion stage and a high frequency inverter feeding a resonant load. The resonant load is the impedance reflected to the inverter side of the high voltage, high frequency

H. Biilent Ertan; Tolga Camlikaya; Okan Demirel; Cosku Kasnakoglu

2000-01-01

63

About the PD-testing of insulation systems with high-frequency voltages  

Microsoft Academic Search

In the last decade, there has been an increasing interest in partial discharges (PD) at high frequency stress on insulation systems. At present, high-frequency working voltages exceeding 100 kHz are often used in low-voltage equipment and the frequencies are still increasing. Due to the switching in the power supplies, the voltage shapes are usually nonsinusoidal. The aspects of these nonsinusoidal

M. Paede; W. Pfeiffer

2002-01-01

64

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

DOEpatents

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.

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

2011-03-22

65

Clarification and measurements of high frequency harmonic resonance by a voltage sourced converter  

Microsoft Academic Search

This work presents the clarification and measurements of a high-order harmonic resonance phenomenon for voltage sourced converters. When a voltage sourced converter is connected to a power system through a cable, there is a possibility that small, high frequency, harmonic voltages due to the converter are magnified by series and parallel resonances. The cause of the high-order harmonic resonance is

Koji Temma; Fujio Ishiguro; Naohiro Toki; Isao Iyoda; John J. Paserba

2005-01-01

66

Clarification and Measurements of High Frequency Harmonic Resonance by a Voltage Sourced Converter  

Microsoft Academic Search

Summary form only given. This paper presents the clarification and measurements of a high-order harmonic resonance phenomenon for voltage sourced converters. When a voltage sourced converter is connected to a power system through a cable, there is a possibility that small, high frequency, harmonic voltages due to the converter are magnified by series and parallel resonances. The cause of the

K. Temma; F. Ishiguro; N. Toki; I. Iyoda; J. Paserba

2006-01-01

67

Voltage and Frequency Controllers for an Asynchronous Generator-Based Isolated Wind Energy Conversion System  

Microsoft Academic Search

This paper presents a state of art on voltage and fre- quency controllers (VFCs) for isolated asynchronous generators (IAGs) for standalone wind energy conversion systems. In wind turbine-driven IAG, magnitude and frequency of the generated voltage vary because of varying consumer loads and wide fluctua- tion in wind speeds. Therefore, new types of VF controllers based on a voltage source

Gaurav Kumar Kasal; Bhim Singh

2011-01-01

68

Lower operation voltage in dual-frequency cholesteric liquid crystals based on the thermodielectric effect.  

PubMed

Dual-frequency cholesteric liquid crystal (DFCLC) devices characteristically require high operation voltage, which hinders their further development in thin-film-transistor driving. Here we report on a lower-voltage switching method based on the thermodielectric effect. This technique entails applying a high-frequency voltage to occasion dielectric oscillation heating so to induce the increase in crossover frequency. The subsequent change in dielectric anisotropy of the DFCLC allows the switching, with a lower operation voltage, from the planar state to the focal conic or homeotropic state. The temperature rise incurred by the dielectric heating is described. PMID:24104303

Hsiao, Yu-Cheng; Lee, Wei

2013-10-01

69

Determining the Minimum Energy Consumption using Dynamic Voltage and Frequency Scaling  

Microsoft Academic Search

While improving raw performance is of primary interest to most users of high-performance computers, energy consumption also is a critical concern. Some microprocessors allow voltage and frequency scaling, which enables a system to reduce CPU power and performance when the CPU is not on the critical path. When properly directed, such dynamic voltage and frequency scaling can produce significant energy

Min Yeol Lim; Vincent W. Freeh

2007-01-01

70

Adaptive, Transparent Frequency and Voltage Scaling of Communication Phases in MPI Programs  

Microsoft Academic Search

Although users of high-performance computing are most interested in raw performance, both energy and power consumption have become critical concerns. Some microprocessors allow frequency and voltage scaling, which enables a system to reduce CPU performance and power when the CPU is not on the critical path. When properly directed, such dynamic frequency and voltage scaling can produce significant energy savings

Min Yeol Lim; Vincent W. Freeh; David K. Lowenthal

2006-01-01

71

MPI and communication - Adaptive, transparent frequency and voltage scaling of communication phases in MPI programs  

Microsoft Academic Search

Although users of high-performance computing are most interested in raw performance, both energy and power consumption have become critical concerns. Some microprocessors allow frequency and voltage scaling, which enables a system to reduce CPU performance and power when the CPU is not on the critical path. When properly directed, such dynamic frequency and voltage scaling can produce significant energy savings

Min Yeol Lim; Vincent W. Freeh; David K. Lowenthal

2006-01-01

72

A method for estimating the frequency and cost of voltage sags  

Microsoft Academic Search

The annual number and cost of voltage sags were determined for five Finnish distribution companies. The method of fault positions was applied for the calculation of voltage sag frequency. The economic consequences were assessed by multiplying the sag frequency and cost by the number of customers. The cost of a single sag was taken from a survey that had been

Pirjo Heine; Pasi Pohjanheimo; Matti Lehtonen; Erkki Lakervi

2002-01-01

73

Profile-based dynamic voltage and frequency scaling for a multiple clock domain microprocessor  

Microsoft Academic Search

A Multiple Clock Domain (MCD) processor addresses the challenges of clock distribution and power dissipation by dividing a chip into several (coarse-grained) clock domains, allowing frequency and voltage to be reduced in domains that are not currently on the application's critical path. Given a reconfiguration mechanism capable of choosing appropriate times and values for voltage\\/frequency scaling, an MCD processor has

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

2003-01-01

74

Position and Speed Estimation of Maglev Train Based on High-frequency Voltage Signal Injection Method  

Microsoft Academic Search

In this paper high-frequency voltage signal injection method was applied based on the machine-saliencies of linear synchronous motor used by maglev train. Three-phase symmetrical high-frequency voltage signals was added to the system before SVPWM regulator, which produced high-frequency current signals containing positive component and negative component. The negative current component included position and velocity signals of the mover of the

Guirong Wang; Hong Xu; Wei Wei

2007-01-01

75

Digital light-to-frequency converter with preset voltage  

SciTech Connect

A digital scene light detecting and integrating circuit is provided with an automatic preset by which the integrating circuit is presignaled to ramp upward to a preselected reference voltage value at which digital pulse counting can immediately begin, thereby subsequently enabling the precise detection and integration of illumination.

Hambly, W.E.

1983-05-24

76

Voltage-mode grid-connected solar inverter with high frequency isolated transformer  

Microsoft Academic Search

A voltage-mode grid-connected solar inverter with high frequency isolated transformer is proposed in this paper. Besides, the functions of MPPT (maximum power point tracking) and the islanding detection are incorporated into the controller of this voltage-mode grid-connected solar inverter. The experimental results show that the performance of this isolated voltage-mode grid-connected photovoltaic generation system is as expected.

Hurng-Liahng Jou; Wen-Jung Chiang; Jinn-Chang Wu

2009-01-01

77

46 CFR 111.01-17 - Voltage and frequency variations.  

Code of Federal Regulations, 2012 CFR

...DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ELECTRICAL ENGINEERING ELECTRIC SYSTEMS-GENERAL REQUIREMENTS General...frequency variations. Unless otherwise stated, electrical equipment must function at variations of at...

2012-10-01

78

A novel digital modulator for voltage source inverter with adaptive switching frequency selection  

Microsoft Academic Search

A novel optimized space vector modulation for voltage source inverter fed induction motor drives, based on an adaptive modulation frequency selection algorithm, is presented in the paper. It considerably reduces the drop voltage due to the dead time effect of the inverter power modules and allows to increase the overall drive performances. The proposed system has been manufactured on a

C. Attaianese; V. Nardi; G. Tomasso

2004-01-01

79

Canadian National Power Quality Survey: frequency of industrial and commercial voltage sags  

Microsoft Academic Search

In 1991, the Canadian Electrical Association (CEA) took a proactive approach to power quality problems and initiated a three-year “Canadian National Power Quality Survey” involving 22 utilities. This paper presents the survey results of the frequency of voltage sags at industrial and commercial sites, monitored at their utilization voltage levels (e.g., 120 V, 347 V) and on the utility primary

Don O. Koval; M. Brent Hughes

1997-01-01

80

Canadian national power quality survey: frequency and duration of voltage sags and surges at industrial sites  

Microsoft Academic Search

The occurrence of voltage sags and surges originating on the primary and secondary sides of industrial facilities can disrupt continuous and noncontinuous industrial computer processes, a costly issue for society. This paper attempts to answer several questions concerning the frequency and duration of voltage sags and surges posed by industrial customers. The answers to these questions are based on the

Don O. Koval; Romela A. Bocancea; Kai Yao; M. Brent Hughes

1998-01-01

81

[Design of a high-voltage insulation testing system of X-ray high frequency generators].  

PubMed

In this paper, we analyze the transformer of X-ray high-voltage high-frequency generators and, have designed and implemented a high-voltage insulation testing system for its oil tank using full-bridge series resonant soft switching PFM DC-DC converter. PMID:18161376

Huang, Yong; Mo, Guo-Ming; Wang, Yan; Wang, Hong-Zhi; Yu, Jie-Ying; Dai, Shu-Guang

2007-09-01

82

Voltage and frequency control of inverter based weak LV network microgrid  

Microsoft Academic Search

In this paper voltage and frequency control of islanded microgrid after intentional and unintentional switching events are investigated. The weak low voltage (LV) network based microgrid consists of two inverter based distributed generation (DG) units. One unit is a storage (battery) unit and the other is a photovoltaic (PV) cell. In this case the battery inverter with rapid response is

H. Laaksonen; P. Saari; R. Komulainen

2005-01-01

83

Features of the measurement of high-frequency ac voltage with electronic voltmeters  

Microsoft Academic Search

The features of the measurement of a high-frequency ac voltage with electronic voltmeters are considered for cases when the\\u000a measured ac voltage is normalized at the input of the electronic-voltmeter probe or at the input of a special connector to\\u000a which the voltmeter probe is connected.

V. V. Krestovskii; G. P. Telitchenko; V. I. Shevtsov

2011-01-01

84

AC power standard using a programmable Josephson voltage standard  

Microsoft Academic Search

This paper describes the implementation of a new quantum-based system for the generation of 120 V, 5 A, sinusoidal active and reactive power over the 50 Hz to 400 Hz frequency range. The system accurately relates the spectral amplitudes and phases of the voltage and current waveforms of the generated power to a programmable Josephson voltage standard (PJVS) using a

B. C. Waltrip; B. Gong; T. L. Nelson; Y. Wang; C. J. Burroughs; A. Rufenacht; S. P. Benz; P. D. Dresselhaus

2008-01-01

85

AC Power Standard Using a Programmable Josephson Voltage Standard  

Microsoft Academic Search

This paper describes the implementation of a new quantum-based system for the generation of 120 V RMS, 5 A RMS, sinusoidal, active, and reactive power over the 50 to 400 Hz frequency range. The system accurately relates the spectral amplitudes and phases of the voltage and current waveforms of the generated power to a programmable Josephson voltage standard (PJVS) by

Bryan C. Waltrip; Bo Gong; Thomas L. Nelson; Yicheng Wang; Alain Rüfenacht; Samuel P. Benz; Paul D. Dresselhaus

2009-01-01

86

Effect of supply voltage frequency on testing of insulation system  

Microsoft Academic Search

This paper deals with the effect of supply frequency on partial discharge phenomena. Results of measurements performed on artificial and practical test objects are compared with computer simulations based on physical models. This comparative analysis points out and explains the differences in partial discharge phenomena observed in tests performed at different frequencies (from 0.1 to 300 Hz). The consequences associated

Andrea Cavallini; Gian Carlo Montanari

2006-01-01

87

Sinusoidal Tracking Control of a PWM Inverter with Inverse System Feedforward Compensation  

NASA Astrophysics Data System (ADS)

Fast responses without any steady-state errors are required for control of a sinusoidal PWM inverter. There are two key points. One is that its reference voltage waveform is not constant but sinusoidal. It is necessary to design a compensator by considering these sinusoidal variations of the reference waveform to get a good steady-state and fast transient response. A sinusoidal tracking compensator which is based on the optimal control and the internal model principle has been proposed by the authors to realize a response with no deviation for a periodic sinusoidal reference input. The other is that compensator and feedback (FB) gains have a trade-off between responses and sensitivities to noises and they can not be too large. Feedforward(FF) compensation can improve responses without alternating system stabilities. This paper proposes a PWM control system which has a sinusoidal FB and an inverse system FF compensators. According to the inverse system FF compensation, appropriate nominal control input values are determined to give the reference steady-state response. Therefore the input values are computed by deconvolving a set of system response equations inversely. The proposed system is investigated and validated through theoretical and experimental results for a rated, an unbalanced, and a rectifier loads by using a simulator Matlab and a DSP system at the switching frequency of 20kHz. The proposed control showed better performances than the original FB and the preview controls.

Kato, Toshiji; Inoue, Kaoru; Watanabe, Fumio

88

Fast transient frequency control voltage regulator using push-pull dynamic leaker circuit  

Microsoft Academic Search

A novel technique of fast transient response for frequency control voltage regulator is presented in this paper. For an embedded switched capacitor based DC-DC converter, poor transient response of frequency control voltage regulator is improved with the help of a push-pull dynamic leaker circuit. Push-pull dynamic leaker paths have been used to reduce both peak and dip at the output

Biswajit Maity; Gaurav Bhagat; Pradip Mandal

2011-01-01

89

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

Microsoft Academic Search

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

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

2001-01-01

90

Novel Current-Mode AC\\/AC Converters With High-Frequency AC Link  

Microsoft Academic Search

A novel circuit-topology family of the current-mode AC\\/AC converter with high-frequency AC link, based on a Flyback converter, is proposed. These circuit topologies, which can transfer one unregulated sinusoidal voltage with high total harmonic distortion (THD) into another regulated constant-frequency sinusoidal voltage with low THD, are composed of input cycloconverter, high-frequency storage transformer, and output cycloconverter. The circuit-topology family includes

Daolian Chen

2008-01-01

91

High-frequency high-voltage high-power DC-to-DC converters  

NASA Astrophysics Data System (ADS)

A simple analysis of the current and voltage waveshapes associated with the power transistor and the power diode in an example current-or-voltage step-up (buck-boost) converter is presented. The purpose of the analysis is to provide an overview of the problems and design trade-offs which must be addressed as high-power high-voltage converters are operated at switching frequencies in the range of 100 kHz and beyond. Although the analysis focuses on the current-or-voltage step-up converter as the vehicle for discussion, the basic principles presented are applicable to other converter topologies as well.

Wilson, T. G.; Owen, H. A.; Wilson, P. M.

1982-09-01

92

Detection of voltage envelope using Prony analysis-Hilbert transform method  

Microsoft Academic Search

This letter presents an efficient method for the detection of the instantaneous flicker level. The technique is based on extracting the magnitudes, frequencies, and phase angles of all frequency components of the voltage envelope using Prony analysis. By reconstructing the voltage waveform as linear combination of sinusoids, Hilbert transform can be applied to the predicted signal to develop the envelope

E. A. Feilat

2006-01-01

93

Microcontroller Based Three-phase Voltage Source Inverter for Alternative Energy Source  

Microsoft Academic Search

This paper presents a high frequency transformer isolated, micro-controller based, three-phase, ac-to-dc voltage source inverter (VSI) for ac motor drives and uninterruptible power supply applications. The proposed converter produces a 3-phase sinusoidal ac output voltage from alternative energy sources (converted to a 12 V dc voltage source) while output voltage magnitude and frequency can both be controlled digitally using a

M. M. A. Rahman; Kurt Hammons; Phillip Beemer; Marcia Isserstedt; Matt Trommater

94

Variable speed constant frequency constant voltage alternator. Annual report  

SciTech Connect

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.

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

1980-07-01

95

Fixed-frequency sliding mode control of a single-phase voltage source inverter with input filter  

Microsoft Academic Search

This paper describes a sliding mode controller for a single-phase voltage source inverter. The work is motivated by power converter systems including two input filters with well separated corner frequencies. Since the inverter input current contains a low frequency component at twice the output voltage frequency, the high frequency input filter is designed to have low damping (no supplementary ohmic

B. Nicolas; M. Fadel; Y. Cheron

1996-01-01

96

Dependence of error sensitivity of frequency on bias voltage in force-balanced micro accelerometer  

NASA Astrophysics Data System (ADS)

To predict more precisely the frequency of force-balanced micro accelerometer with different bias voltages, the effects of bias voltages on error sensitivity of frequency is studied. The resonance frequency of accelerometer under closed loop control is derived according to its operation principle, and its error sensitivity is derived and analyzed under over etching structure according to the characteristics of Deep Reaction Ion Etching (DRIE). Based on the theoretical results, micro accelerometer is fabricated and tested to study the influences of AC bias voltage and DC bias voltage on sensitivity, respectively. Experimental results indicate that the relative errors between test data and theory data are less than 7%, and the fluctuating value of error sensitivity under the range of voltage adjustment is less than 0.01 ?m-1. It is concluded that the error sensitivity with designed parameters of structure, circuit and process error can be used to predict the frequency of accelerometer with no need to consider the influence of bias voltage.

Chen, Lili; Zhou, Wu

2013-05-01

97

Frequency Characteristics Measurement of Overhead High-Voltage Power-Line in Low Radio-Frequency Range  

Microsoft Academic Search

This paper presents measurement results of frequency characteristics of the high-voltage power line in low radio-frequency range: amplitude and phase characteristic, group delay, and input impedance. Measurement results for the 400-kV overhead power-line under operation are presented together with the developed measurement methodology. The methodology provides a method to measure amplitude and phase characteristics, group delay and the return loss

M. Zajc; N. Suljanovic; A. Mujcic; J. F. Tasic

2007-01-01

98

A FPGA-based sweep-frequency voltage source for EIT system  

Microsoft Academic Search

A FPGA-based sweep-frequency voltage source for EIT is designed in this paper. There are three methods for generating sine signal for EIT, including the special function generator, the general purpose chip, and the ordinary oscillator circuit. The special function generator has some inherent characteristics of wide-band frequency and stable output. But the range of frequency is so broad that it

Dechun Zhao; Chaoshi Ren; Hong Sha; Zhangyong Li; Wei Wang

2010-01-01

99

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

Microsoft Academic Search

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

Ion Radu; Ray Bartnikas; Michael R. Wertheimer

2003-01-01

100

Voltage sag mitigation for a high frequency multistage power conversion system  

Microsoft Academic Search

A multistage power conversion scheme, capable of providing a regulated power supply despite disturbances in the source voltage or changes in the output load, is proposed. The high frequency power conversion system also provides compensation for acute voltage sags\\/swells and a faster transient response by employing appropriately controlled power electronics converters. Through the utilization of a bidirectional buck-boost DC-DC converter

M. Peterson; B. N. Singh

2008-01-01

101

Voltage and Frequency Control of a Stand Alone Brushless Wind Electric Generation Using Generalized Impedance Controller  

Microsoft Academic Search

In this paper, a new strategy for the control of terminal voltage and frequency of a stand-alone self-excited induction generator-(SEIG) based wind generator, working with variable speed and load is proposed. With a generalized impedance controller (GIC) (voltage source pulsewidth-modulated inverter with a dc-link battery), a new strategy to maintain the active and reactive power balance at the SEIG terminals

B. Venkatesa Perumal; Jayanta K. Chatterjee

2008-01-01

102

A novel compact repetitive frequency voltage booster based on magnetic switches and Fitch generator.  

PubMed

In this paper, a novel repetitive frequency voltage booster (named repetitive Fitch booster by the authors) based on magnetic switches and Fitch generators is proposed. The principle of operation is to charge capacitors in parallel when magnetic switches (MSs) are unsaturated and reverse voltage polarity of every other capacitor when MSs saturate. With the principle, circuit topology of a 4-stage repetitive Fitch booster (RFB) is presented. Simulation as well as experiment shows its feasibility in boosting voltage and compressing rise-time. In simulation, the input voltage of 100 V is boosted to 372 V, while test stand yields output voltage with frequency of 1 kHz, amplitude of 19 kV with each capacitor charged to about 5.6 kV, and rise-time compression from 7.3 ?s to 700 ns. Meanwhile, calculations show that the 4-stage RFB effectively reduces core volume by about half, from 1093.5 cm(3) to 585.2 cm(3). Furthermore, design rules are proposed so that topologies of RFBs with stages other than four can be conveniently derived. As an example, an 8-stage RFB is proposed and verified with circuit simulation, which shows an output voltage of 759 V with the input voltage of 100 V. PMID:22852688

Ren, Hang; Ding, Weidong; Wu, Jiawei

2012-07-01

103

Experimental and numerical studies on voltage distribution in capacitively coupled very high-frequency plasmas  

NASA Astrophysics Data System (ADS)

A non-uniform voltage distribution across a driven electrode results in inhomogeneous film deposition in large-area, very high-frequency (VHF) plasma reactors. Here we perform experimental and numerical studies on the voltage distribution across the electrode. Two kinds of dedicated vacuum chambers are prepared for one- and two-dimensional observations of the voltage and the plasma distributions. A comparison between the measured voltage and the plasma distribution clearly shows a good agreement between the two. In principle the plasma distribution is governed by the standing wave of the voltage on the driven electrode for an at least one-dimensional electrode. A numerical model based on transmission-line modelling is presented for calculating the voltage distribution. The influence of plasma conditions such as the electron density and the sheath length included in the model on the voltage distribution is investigated through comparison of the model predictions with the experimental results. The correlation between the plasma conditions and the propagation constant of the model suggests that the sheath length dominates the wavelength; in contrast, the electron density dominates the decay of the wave propagation. Using the parameters of the plasma conditions estimated from the experimental results, the model can predict the voltage distribution across a ladder electrode of size 45 cm × 55 cm in a large-area VHF plasma reactor.

Satake, Koji; Yamakoshi, Hideo; Noda, Matsuhei

2004-08-01

104

Analog-to-digital conversion for low-frequency waveforms based on the Josephson voltage standard  

NASA Astrophysics Data System (ADS)

A waveform synthesizer adopting a superconductor-normal metal-superconductor junction array has been developed, which can generate arbitrary stepwise waveforms with a number of quantum-voltage steps up to 1 V level amplitude. As an application of the synthesizer, we have built a sampling voltmeter that measures the differential voltages between a sinusoidal waveform produced by a semiconductor-based ac source and the Josephson waveforms. We carried out extensive sampling measurements for a 50 Hz sine wave with 1 V amplitude, applying sampling apertures in the range of 55 µs <=ta <= 130 µs and using Josephson waveforms with 32, 60, 80 and 100 quantum steps. From the measurements, the amplitude of the ac waveform was determined with a type A uncertainty (k = 2) of 0.15 µV. Also, we elucidated how the phase jitter in the ac waveform is reflected in the overall uncertainty for the measurements. The type B uncertainty due to the jitter is at least one order of magnitude smaller than the type A uncertainty.

Kim, Mun-Seog; Kim, Kyu-Tae; Kim, Wan-Seop; Chong, Yonuk; Kwon, Sung-Won

2010-11-01

105

Frequency dependence of the onset voltage of electroconvection in the nematic liquid crystal N4  

NASA Astrophysics Data System (ADS)

Onset voltages Vc of electroconvection in a nematic liquid crystal (NLC) cell were measured as a function of the drive frequency ?/ 2 ?. The cell (from E.H.C Co, Ltd Japan) had a nominal spacing of 25 ?m and planar alignment. It was filled with the NLC Merck phase IV (N4). The NLC was doped with 0.1% by weight of tetra butylammonium bromide(TBAB) and the conductivity was near 1.0 × 10-6 (? m)-1 at 30^oC. At low frequencies (15 to 80Hz) the onset voltage dropped as the frequency increased. This is contrary to the usual interpretation of the standard model which yields Vc (1+?^2 ?^2)/[?^2-(1+?^2 ?^2)] (? is related to NLC material properities), with the charge relaxation time ?=?/ ( 4? ?) assumed to be independent of ?. Measurements at higher frequencies agreed reasonably with the standard model prediction. Further measurements using an AC bridge revealed that the dielectric constant ? is strongly frequency dependent at low frequencies, whereas the conductivity ? was roughly constant. Taking into account the frequency dependence of ? (and thus of ?), the onset-voltage measurements agreed fairly well with the standard-model prediction.

Xu, Xiaochao; Bowers, Steve; Bajaj, Kapil; Ahlers, Guenter

2003-03-01

106

Sinusoidal Current-Tracking Control for Utility Interactive Inverter with an LCL Filter  

NASA Astrophysics Data System (ADS)

A voltage source inverter with an LCL filter is often used for a utility interface to control its output current to a grid side because of its harmonic reduction advantages. The integral compensator is often used to reduce the steady-state errors. However, there is always a control delay due to sinusoidal variations. This paper proposes a digital sinusoidal compensator which is based on the internal model principle to realize a fast sinusoidal response with no delay. It is based on the internal model principle to realize a response with no deviation for a periodic sinusoidal reference input. It has a simple numerator and a denominator z2-2zcos?T +1 of a transfer function which is equal to the z function of a sinusoidal waveform of the angular frequency ? and the sample time T. Compensator and feedback gains of the inverter are determined by the dead-beat or the optimal control principle. The proposed method is investigated for performances and it is validated through simulation and experimental results by a DSP control system.

Kato, Toshiji; Inoue, Kaoru; Donomoto, Yoshihisa

107

Dead Beat Microprocessor Control of PWM Inverter for Sinusoidal Output Waveform Synthesis  

Microsoft Academic Search

A new control technique based on dead beat control theory to obtain a nearly sinusoidal PWM inverter output voltage is described. The closed-loop digital feedback system measures the output and controls the inverter switches to generate the required pulsewidth-modulated (PWM) pattern to produce low total harmonic distortion (THD) sinusoidal output voltage. This scheme inherently provides very good voltage regulation, phase

Kalyan P. Gokhale; Atsuo Kawamura; Richard G. Hoft

1987-01-01

108

Effect of frequency on two-phase flow regimes under high-voltage AC electric fields  

Microsoft Academic Search

The effect of high-voltage AC electric fields on two-phase flow regime redistribution for flowing refrigerant HFC-134a in a circular tube has been investigated. In particular, the effect of the frequency of an applied square wave between 0 and 8kV was studied for frequencies in the range 4Hz to 1kHz. The electric field was applied through a central electrode along the

H. Sadek; J. S. Cotton; C. Y. Ching; M. Shoukri

2008-01-01

109

A low-power high-sensitivity CMOS voltage-to-frequency converter  

Microsoft Academic Search

This paper presents a low-cost high-speed CMOS voltage-to-frequency converter (VFC) which targets front-end sensor interfacing in wireless sensor networks applications. The proposed VFC, designed in a 0.35 mum CMOS technology supplied at 3 V, is very simple, obtaining at the same time high performance characteristics: it operates with a power consumption below 1.03 mW at output frequencies ranging from 1.198

B. Calvo; N. Medrano; S. Celma; M. T. Sanz

2009-01-01

110

A low-voltage mobility-based frequency reference for crystal-less ULP radios  

Microsoft Academic Search

The design of a 100 kHz frequency reference based on the electron mobility in a MOS transistor is presented. The proposed low-voltage low-power circuit requires no off-chip components, making it suitable for Wireless Sensor Networks (WSN) applications. After one-point calibration the spread of its output frequency is less than 1.1% (3sigma) over the temperature range from -22degC to 85degC. Fabricated

Fabio Sebastiano; Lucien Breems; Kofi Makinwa; Salvatore Drago; Domine Leenaerts; Bram Nauta

2008-01-01

111

A Low-Voltage Mobility-Based Frequency Reference for Crystal-Less ULP Radios  

Microsoft Academic Search

The design of a 100 kHz frequency reference based on the electron mobility in a MOS transistor is presented. The proposed low-voltage low-power circuit requires no off-chip components, making it suitable for application in wireless sensor networks (WSN). After a single-point calibration, the spread of its output frequency is less than 1.1% (3sigma) over the temperature range from -22degC to

Fabio Sebastiano; Lucien J. Breems; Kofi A. A. Makinwa; Salvatore Dargo; Domine M. W. Leenaerts; Bram Nauta

2009-01-01

112

Light flicker evaluation of power systems based on frequency spectrum of voltage waveforms  

Microsoft Academic Search

In this paper, a frequency domain approach is proposed to measure the light flicker of the electricity transmission systems. Analytical expressions of the instantaneous light flicker sensation are obtained beginning from the voltage waveform and these expressions are used to obtain a flicker estimation method based on the IEC flickermeter. In the proposed method, the leakage effect of the FFT

N. Kose; O. Salor; I. Cadirci

2009-01-01

113

Evaluation of Dynamic Voltage and Frequency Scaling as a Differential Power Analysis Countermeasure  

Microsoft Academic Search

Differential power analysis (DPA) attack is a major concern for secure embedded devices (Ravi et al., 2004)-(Ors et al., 2004). Currently proposed countermeasures (Pramstaller, 2005)-(Tin and Verbauwhede, 2004) to prevent DPA imposes significant area, power and performance overheads. In addition they either require special standard cell library and design flows or algorithmic modifications. Recently, random dynamic voltage and frequency scaling

Karthik Baddam; Mark Zwolinski

2007-01-01

114

Effects of high frequency voltage stress on air insulation and solid insulation  

Microsoft Academic Search

Air insulation and solid insulation are the most common approaches to achieve adequate electrical insulation. However, with the increase in instances of high-frequency voltage stress, there are important differences in dimensioning these product safety approaches. This paper discusses the phenomenon of partial discharge, and its impact on the behavior of clearances, creepage distances, and solid insulation respectively. To shorten the

Flore Chiang

2010-01-01

115

Utilization of the voltage frequency converter or digital representation and documentation of transient reactor operation  

Microsoft Academic Search

The ease and speed of handling transient data is enhanced by the use of a voltage to frequency converter (VFC). This analogue to digital semiconductor device provides an inexpensive and portable alternative to electro-mechanical recorders and hand entry of data into computer codes. The VFC used at The University of Arizona is a Teledyne Philbrick 4705\\/01. A zero to positive

Doane; Harry J

1986-01-01

116

Voltage and frequency control with neutral current compensation in an isolated wind energy conversion system  

Microsoft Academic Search

This paper presents a voltage and frequency controller with neutral current compensation in an isolated wind energy conversion system employing a capacitor excited asynchronous generator (CEAG). In isolated applications, because of unavailability of the neutral point at the generator terminals, it is difficult to access the neutral wire from the source. In view of this, a transformer integrated with a

G. K. Kasal; B. Singh; A. Chandra; K. Al-Haddad

2008-01-01

117

New frequency/voltage converters for ac-electrogravimetric measurements based on fast quartz crystal microbalance  

SciTech Connect

A better understanding of the mechanisms located at the solid/electrolyte interface is becoming essential to the development of new applications in the electrochemical fields. The fast quartz crystal microbalance is an attractive and powerful gravimetric sensor which can be used in the dynamic regime to determine a mass/potential transfer function. The principle is equivalent to classical electrochemical impedance measurements; the only difference is the determination of mass changes given by the quartz crystal microbalance rather than current changes following sine wave modulations of the applied potential. This function appears very well adapted to characterize ionic exchanges at the electrochemical interface. Frequency/voltage converters are the key devices in translating the microbalance frequency response in terms of a continuous voltage change. The latter allows the transfer function to be obtained via a frequency response analyzer. Different converters were tested in this work in order to improve the performances of the experimental setup.

Gabrielli, C.; Perrot, H.; Rose, D.; Rubin, A.; Toque, J. P.; Pham, M. C.; Piro, B. [LISE--UPR 15 du CNRS, Universite Pierre et Marie Curie-Paris 6, 4, place Jussieu (case 133), 75252 Paris Cedex 05 (France); LISE-UPR 15 du CNRS, Universite Pierre et Marie Curie-Paris 6, 4, place Jussieu (case 133), 75252 Paris Cedex 05, France and ITODYS, Universite Denis Diderot-Paris 7, 1, rue Guy de la Brosse, 75005 Paris (France); LISE-UPR 15 du CNRS, Universite Pierre et Marie Curie-Paris 6, 4, place Jussieu (case 133), 75252 Paris Cedex 05 (France); ITODYS, Universite Denis Diderot-Paris 7, 1, rue Guy de la Brosse, 75005 Paris (France)

2007-07-15

118

New frequency/voltage converters for ac-electrogravimetric measurements based on fast quartz crystal microbalance  

NASA Astrophysics Data System (ADS)

A better understanding of the mechanisms located at the solid/electrolyte interface is becoming essential to the development of new applications in the electrochemical fields. The fast quartz crystal microbalance is an attractive and powerful gravimetric sensor which can be used in the dynamic regime to determine a mass/potential transfer function. The principle is equivalent to classical electrochemical impedance measurements; the only difference is the determination of mass changes given by the quartz crystal microbalance rather than current changes following sine wave modulations of the applied potential. This function appears very well adapted to characterize ionic exchanges at the electrochemical interface. Frequency/voltage converters are the key devices in translating the microbalance frequency response in terms of a continuous voltage change. The latter allows the transfer function to be obtained via a frequency response analyzer. Different converters were tested in this work in order to improve the performances of the experimental setup.

Gabrielli, C.; Perrot, H.; Rose, D.; Rubin, A.; Toqué, J. P.; Pham, M. C.; Piro, B.

2007-07-01

119

Sinusoids: Applications and Modeling  

NSDL National Science Digital Library

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.

Roberts, Lila F.; Hill, David R.

2004-07-21

120

Design and implementation of a high-voltage high-frequency pulse power generation system for plasma applications  

Microsoft Academic Search

This paper presents a high-voltage high-frequency inverter for atmosphere plasma applications. The proposed system is consisted of a PFC rectifier, a voltage-source full-bridge inverter with phase-shift control, a high-voltage high-frequency transformer, and a plasma reactor. The mathematical models including the inverter and the plasma reactor have been described. The PFC rectifier is achieved by UC3854 based controller, and UC 3895

M. T. Tsai; C. W. Ke

2009-01-01

121

Calcium channel dynamics limit synaptic release in response to prosthetic stimulation with sinusoidal waveforms  

PubMed Central

Extracellular electric stimulation with sinusoidal waveforms has been shown to allow preferential activation of individual types of retinal neurons by varying stimulus frequency. It is important to understand the mechanisms underlying this frequency dependence as a step towards improving methods of preferential activation. In order to elucidate these mechanisms, we implemented a morphologically realistic model of a retinal bipolar cell and measured the response to extracellular stimulation with sinusoidal waveforms. We compared the frequency response of a passive membrane model to the kinetics of voltage-gated calcium channels that mediate synaptic release. The passive electrical properties of the membrane exhibited lowpass filtering with a relatively high cutoff frequency (nominal value = 717 Hz). This cutoff frequency was dependent on intra-axonal resistance, with shorter and wider axons yielding higher cutoff frequencies. However, we found that the cutoff frequency of bipolar cell synaptic release was primarily limited by the relatively slow opening kinetics of Land T-type calcium channels. The cutoff frequency of calcium currents depended nonlinearly on stimulus amplitude, but remained lower than the cutoff frequency of the passive membrane model for a large range of membrane potential fluctuations. These results suggest that while it may be possible to modulate the membrane potential of bipolar cells over a wide range of stimulus frequencies, synaptic release will only be initiated at the lower end of this range.

Freeman, Daniel K.; Jeng, Jed S.; Kelly, Shawn K.; Hartveit, Espen; Fried, Shelley I.

2011-01-01

122

Calcium channel dynamics limit synaptic release in response to prosthetic stimulation with sinusoidal waveforms  

NASA Astrophysics Data System (ADS)

Extracellular electric stimulation with sinusoidal waveforms has been shown to allow preferential activation of individual types of retinal neurons by varying stimulus frequency. It is important to understand the mechanisms underlying this frequency dependence as a step toward improving methods of preferential activation. In order to elucidate these mechanisms, we implemented a morphologically realistic model of a retinal bipolar cell and measured the response to extracellular stimulation with sinusoidal waveforms. We compared the frequency response of a passive membrane model to the kinetics of voltage-gated calcium channels that mediate synaptic release. The passive electrical properties of the membrane exhibited lowpass filtering with a relatively high cutoff frequency (nominal value = 717 Hz). This cutoff frequency was dependent on intra-axonal resistance, with shorter and wider axons yielding higher cutoff frequencies. However, we found that the cutoff frequency of bipolar cell synaptic release was primarily limited by the relatively slow opening kinetics of L- and T-type calcium channels. The cutoff frequency of calcium currents depended nonlinearly on stimulus amplitude, but remained lower than the cutoff frequency of the passive membrane model for a large range of membrane potential fluctuations. These results suggest that while it may be possible to modulate the membrane potential of bipolar cells over a wide range of stimulus frequencies, synaptic release will only be initiated at the lower end of this range.

Freeman, Daniel K.; Jeng, Jed S.; Kelly, Shawn K.; Hartveit, Espen; Fried, Shelley I.

2011-08-01

123

Adaptive Scheme for Minimal Load Shedding Utilizing Synchrophasor Measurements to Ensure Frequency and Voltage Stability  

Microsoft Academic Search

This article presents a new scheme for load curtailment in the power system under critical contingencies that may pose a threat to the frequency and voltage stability of the system. The proposed scheme is based on a two-stage load-shedding strategy. In the first stage, disturbances have been classified based on the computed value of the disturbance power, and the load-shedding

K. Seethalekshmi; S. N. Singh; S. C. Srivastava

2010-01-01

124

A frequency-output fiber optic voltage sensor with temperature compensation for power systems  

Microsoft Academic Search

We present a frequency-output fiber optic voltage sensor for power systems with temperature compensated response. The sensor employs PZT-type ceramic tubes, which are interrogated by a length of single-mode fiber coiled onto the tubes and a Mach–Zehnder interferometer. The combination of piezoelectric tubes with properties exhibiting opposite behavior to temperature changes is successfully exploited to passively compensate the temperature sensitivity

Ll. Mart??nez-León; A. D??ez; J. L. Cruz; M. V. Andrés

2003-01-01

125

Zero-Voltage-Switching Bi-Frequency Push-Pull Driver for Liquid Crystal Displays  

NASA Astrophysics Data System (ADS)

In this paper, a bi-frequency control based zero-voltage-switching push-pull driver with a wide dimming range is proposed for the cold cathode fluorescent lamp (CCFL) based back lighting of the liquid crystal display (LCD). As a result, not only the design of the driver transformer can be simplified but also the efficiency of CCFL can be improved. Finally, a prototype is constructed for verifying the effectiveness of the proposed LCD driver.

Chern, Gwo-Tarng; Shieh, Jenn-Jong

126

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

Microsoft Academic Search

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

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

2006-01-01

127

Sensorless optimal sinusoidal brushless direct current for hard disk drives  

NASA Astrophysics Data System (ADS)

Initiated by the availability of digital signal processors and emergence of new applications, market demands for permanent magnet synchronous motors have been surging. As its back-emf is sinusoidal, the drive current should also be sinusoidal for reducing the torque ripple. However, in applications like hard disk drives, brushless direct current (BLDC) drive is adopted instead of sinusoidal drive for simplification. The adoption, however, comes at the expense of increased harmonics, losses, torque pulsations, and acoustics. In this paper, we propose a sensorless optimal sinusoidal BLDC drive. First and foremost, the derivation for an optimal sinusoidal drive is presented, and a power angle control scheme is proposed to achieve an optimal sinusoidal BLDC. The scheme maintains linear relationship between the motor speed and drive voltage. In an attempt to execute the sensorless drive, an innovative power angle measurement scheme is devised, which takes advantage of the freewheeling diodes and measures the power angle through the detection of diode voltage drops. The objectives as laid out will be presented and discussed in this paper, supported by derivations, simulations, and experimental results. The proposed scheme is straightforward, brings about the benefits of sensorless sinusoidal drive, negates the need for current sensors by utilizing the freewheeling diodes, and does not incur additional cost.

Soh, C. S.; Bi, C.

2009-04-01

128

Monitoring voltage-sensitive membrane impedance change using radio frequency interrogation.  

PubMed

Here we present a new technique to monitor dynamic conformational changes in voltage-sensitive membrane-bound proteins using radio frequency (RF) impedance measurements. Xenopus oocytes were transfected to express ShakerB-IR K(+) ion channels, and step changes in membrane potential were applied using two-electrode voltage clamp (TEVC). Simultaneously, bipolar extracellular electrodes were used to measure the RF electrical impedance across the cell (300 kHz - 1 MHz). RF current will either pass through the media, around the cell, or displace charge across the cell membrane. The change in displacement current in the cell membrane during voltage clamp resulted in measurable RF impedance change. RF impedance change during DC membrane depolarization was significantly greater in ShakerB-IR expressing oocytes than in endogenous controls at 300 kHz, 500 kHz and, to a lesser extent, 1 MHz. Since the RF were too high to modulate ShakerB-IR protein conformational state (e.g. open channel probability), impedance changes are interpreted as reflections of voltage-dependent protein conformation and associated biophysics such as ion-channel dipole interactions, fluctuations in bound water, or charged lipid head-group rotations. PMID:21097203

Dharia, Sameera; Rabbitt, Richard D

2010-01-01

129

Very-low-frequency high-voltage technique offers improved apparatus field-test results. [Insulation at high capacitance  

SciTech Connect

Very-low-frequency (vlf) high-voltage field tests detect insulation deterioration and warn of potential failure in situations where conventional equipment testing is not possible. The technique provides better information than direct-current testing, and achieves an alternating-current - voltage gradient. Applications of vlf diagnostic testing include installed polyethylene power cable and large rotating machines for measurements of partial dischage peaks plotted against voltage or phase, average partial discharge, and power factor angle. 5 figures. (DCK)

Reynolds, P.H.

1983-02-01

130

Spontaneous low-frequency voltage oscillations in frog saccular hair cells  

PubMed Central

Spontaneous membrane voltage oscillations were found in 27 of 130 isolated frog saccular hair cells. Voltage oscillations had a mean peak-to-peak amplitude of 23 mV and a mean oscillatory frequency of 4.6 Hz. When compared with non-oscillatory cells, oscillatory cells had significantly greater hyperpolarization-activated and lower depolarization-activated current densities. Two components, the hyperpolarization-activated cation current, Ih, and the K+-selective inward-rectifier current, IK1, contributed to the hyperpolarization-activated current, as assessed by the use of the IK1-selective inhibitor Ba2+ and the Ih-selective inhibitor ZD-7288. Five depolarization-activated currents were present in these cells (transient IBK, sustained IBK, IDRK, IA, and ICa), and all were found to have significantly lower densities in oscillatory cells than in non-oscillatory cells (revealed by using TEA to block IBK, 4-AP to block IDRK, and prepulses at different voltages to isolate IA). Bath application of either Ba2+ or ZD-7288 suppressed spontaneous voltage oscillations, indicating that Ih and IK1 are required for generating this activity. On the contrary, TEA or Cd2+ did not inhibit this activity, suggesting that IBK and ICa do not contribute. A mathematical model has been developed to test the interpretation derived from the pharmacological and biophysical data. This model indicates that spontaneous voltage oscillations can be generated when the electrophysiological features of oscillatory cells are used. The oscillatory behaviour is principally driven by the activity of IK1 and Ih, with IA playing a modulatory role. In addition, the model indicates that the high densities of depolarization-activated currents expressed by non-oscillatory cells help to stabilize the resting membrane potential, thus preventing the spontaneous oscillations.

Catacuzzeno, Luigi; Fioretti, Bernard; Perin, Paola; Franciolini, Fabio

2004-01-01

131

Study of Improving Stepping Motor Torque-Frequency Characteristic by Feedback Control of High and Low Voltage Driving Circuit  

Microsoft Academic Search

To improve the stepping motor torque-frequency characteristic, a kind of double voltage driving circuit with feedback control for stepping motor was designed and discussed. The paper describes the construction, principle and some parameters' calculation. The loading capacity of 3 kinds driving circuits has been compared with each other by experiments. Double voltage driving circuit with feedback control can improve driving

Jing Kang; Hong-ying Hu; Guang-yao Meng

2007-01-01

132

Quasi-Sinusoidal Geomagnetic Variations at Geomagnetic Midlatitude.  

National Technical Information Service (NTIS)

Three-component quasi-sinusoidal geomagnetic variations (micropulsations) at Concord, Massachusetts for a five month period have been reduced to hourly average amplitudes in six contiguous octave frequency bands covering the period range from 16 to 1024 s...

J. H. Frey W. L. Fischer

1972-01-01

133

Lifetime characteristics of magnet wires under high frequency pulsating voltage and high temperature  

NASA Astrophysics Data System (ADS)

Accelerated life tests have been conducted on samples of fine gauge magnet wires meeting NEMA MW-80C specifications. Air insulted twisted pairs of magnet wires, sizes AWG 43 and 41, were investigated. Likewise, twisted pairs of AWG 41 magnet wire vacuum-impregnated with epoxy resin have been examined. The life tests were conducted at high-frequency pulsating voltages and high temperatures in an attempt to study their lifetime characteristics and develop life models to evaluate the insulation lifetime under these conditions. The scatters of failure times of the electrical-thermal accelerated life tests are presented statistically by a Weibull probability distribution. The Weibull distribution was combined with the electrical-thermal life model. Different forms of electrical-thermal life models were investigated. The parameters of the applicable life models were estimated using maximum likelihood estimation. Moreover, electrical-thermal-frequency models based on multiple linear regression were also examined.

Abu-Al-Feilat, Eyad A.

134

Magnetic power inverter: AC voltage generation from DC magnetic fields  

NASA Astrophysics Data System (ADS)

We propose a method that allows power conversion from DC magnetic fields to AC electric voltages using domain wall (DW) motion in ferromagnetic nanowires. The device concept relies on spinmotive force, voltage generation due to magnetization dynamics. Sinusoidal modulation of the nanowire width introduces a periodic potential for a DW, the gradient of which exerts variable pressure on the traveling DW. This results in time variation of the DW precession frequency and the associated voltage. Using a one-dimensional model, we show that the frequency and amplitude of the AC outputs can be tuned by the DC magnetic fields and wire-design.

Ieda, Jun'ichi; Maekawa, Sadamichi

2012-12-01

135

Analysis of transistor and snubber turn-off dynamics in high-frequency high-voltage high-power converters  

NASA Astrophysics Data System (ADS)

Dc to dc converters which operate reliably and efficiently at switching frequencies high enough to effect substantial reductions in the size and weight of converter energy storage elements are studied. A two winding current or voltage stepup (buck boost) dc-to-dc converter power stage submodule designed to operate in the 2.5-kW range, with an input voltage range of 110 to 180 V dc, and an output voltage of 250 V dc is emphasized. In order to assess the limitations of present day component and circuit technologies, a design goal switching frequency of 10 kHz was maintained. The converter design requirements represent a unique combination of high frequency, high voltage, and high power operation. The turn off dynamics of the primary circuit power switching transistor and its associated turn off snubber circuitry are investigated.

Wilson, P. M.; Wilson, T. G.; Owen, H. A., Jr.

136

Direct Rotor-Position Estimation Method for Salient Pole PM Motor by Using High-Frequency Voltage  

NASA Astrophysics Data System (ADS)

Recently, a number of methods have been proposed for estimating the rotor position of a salient pole PM motor, and methods using a high-frequency voltage can estimate the rotor position accurately, even at low speeds. In the conventional method, the rotor position is estimated indirectly by minimizing the position error signal associated with the difference between the estimated position and the real one. This paper proposes a novel direct rotor-position estimation method for salient pole PM motors. In this method, a rotating high-frequency voltage is supplied to the motor, and the rotor position is estimated directly from the high-frequency current in the motor.

Ito, Masato; Kinpara, Yoshihiko

137

A high frequency active voltage doubler in standard CMOS using offset-controlled comparators for inductive power transmission.  

PubMed

In this paper, we present a fully integrated active voltage doubler in CMOS technology using offset-controlled high speed comparators for extending the range of inductive power transmission to implantable microelectronic devices (IMD) and radio-frequency identification (RFID) tags. This active voltage doubler provides considerably higher power conversion efficiency (PCE) and lower dropout voltage compared to its passive counterpart and requires lower input voltage than active rectifiers, leading to reliable and efficient operation with weakly coupled inductive links. The offset-controlled functions in the comparators compensate for turn-on and turn-off delays to not only maximize the forward charging current to the load but also minimize the back current, optimizing PCE in the high frequency (HF) band. We fabricated the active voltage doubler in a 0.5-?m 3M2P std . CMOS process, occupying 0.144 mm(2) of chip area. With 1.46 V peak AC input at 13.56 MHz, the active voltage doubler provides 2.4 V DC output across a 1 k? load, achieving the highest PCE = 79% ever reported at this frequency. In addition, the built-in start-up circuit ensures a reliable operation at lower voltages. PMID:23853321

Lee, Hyung-Min; Ghovanloo, Maysam

2013-06-01

138

Low-voltage operation of a CMOS image sensor based on pulse frequency modulation  

NASA Astrophysics Data System (ADS)

Inspired by biological information scheme, pulse frequency modulation (PFM) technique is robust for noise sources due to its digital encode of analog signals. In a viewpoint of image sensors, PFM is also useful for a wide dynamic range and has already been demonstrated over 60 dB. We have designed a pixel circuit of a CMOS image sensor using PFM for the next generation architecture of vision chips. The chip is fabricated using a standard 0.35 micrometers double poly, triple metal CMOS technology. The photodiode is a parasitic pn diode between p-well and n-diffusion with the size of 2 micrometers squares. The top of the photodiode is covered with third metal and 1 micrometers square hole is open for aperture. Feedback circuits consist of a Schmitt trigger and two inverters. We have demonstrated by introducing PFM the chip works well under the power supply voltage of 0.55V with 50 dB. Such a low voltage operation suggests deep sub-micron technologies, for example, 0.18 micrometers technologies could be applied to the sensor. The other important point in our chip is that the photodiode is very small in size of 2 micrometers by 2 micrometers with the aperture size of 1 micrometers by 1 micrometers . This enables us to realize an image sensor with a small fill factor, which is very useful for vision chips where functional circuits are integrated in each pixel.

Ohta, Jun; Sakata, Hirohiko; Tokuda, Takashi; Nunoshita, Masahiro

2001-05-01

139

Measurement of low frequency relative permittivity of room temperature molten salts by triangular waveform voltage  

NASA Astrophysics Data System (ADS)

We present a low-cost experimental method for measuring cell resistance and capacitance independently. In this technique a triangular waveform voltage excitation is adopted. Conductivity calibration is straightforward. However, it is demonstrated that a specific calibration procedure needs to be followed to obtain correct relative permittivity values for highly conductive liquids. It is also required to measure conductivity in order to measure relative permittivity for highly conductive liquids. Using this technique, the relative permittivities of room temperature molten salt 1-ethyl-3-methylimidazolium tetrafluoroborate (EMImBF4) and 1-butyl-3-methylimidazolium tetrafluoroborate (BMImBF4) were measured. To our knowledge, this is the first ever directly measured low frequency relative permittivity value of highly conducting EMImBF4 and BMImBF4.

Wu, Jianping; Stark, John P. W.

2006-04-01

140

Utilization of the voltage frequency converter or digital representation and documentation of transient reactor operation  

SciTech Connect

The ease and speed of handling transient data is enhanced by the use of a voltage to frequency converter (VFC). This analogue to digital semiconductor device provides an inexpensive and portable alternative to electro-mechanical recorders and hand entry of data into computer codes. The VFC used at The University of Arizona is a Teledyne Philbrick 4705/01. A zero to positive ten volt input signal provides a zero to one megahertz output signal which is TTL/DTL compatible. VFC is used at the University of Arizona to collect data for super prompt critical TRIGA excursions. The VFC provides a low cost, convenient method of transient data storage and retrieval for experimentation and laboratory demonstration.

Doane, Harry J. [Department of Nuclear and Energy Engineering, University of Arizona, Tucson, AZ (United States)

1986-07-01

141

Analog VLSI design of multi-phase voltage doublers with frequency regulation  

Microsoft Academic Search

This paper proposes a new organization of charge pump circuits based on a voltage doubler that takes a DC input and outputs a doubled DC voltage. By cascading n multi-phase voltage doublers (MPVD), the resulting charge pump has the voltage gain equal to 2n. It needs n clock pairs to control the pumping process, MPVD is a minimum capacitance realization

Fengjing Qiu; Janusz A. Starzyk; Ying-Wei Jan

1999-01-01

142

Precision Differential Sampling Measurements of Low-Frequency Synthesized Sine Waves With an AC Programmable Josephson Voltage Standard  

Microsoft Academic Search

We have developed a precision technique to measure sine-wave sources with the use of a quantum-accurate AC programmable Josephson voltage standard. This paper describes a differential method that uses an integrating sampling voltmeter to precisely determine the amplitude and phase of high-purity and low-frequency (a few hundred hertz or less) sine-wave voltages. We have performed a variety of measurements to

Alain Rüfenacht; Charles J. Burroughs; Samuel P. Benz; Paul D. Dresselhaus; Bryan C. Waltrip; Thomas L. Nelson

2009-01-01

143

Voltage and Frequency Controller for a Three-Phase Four-Wire Autonomous Wind Energy Conversion System  

Microsoft Academic Search

This paper deals with control of voltage and frequency of an autonomous wind energy conversion system (AWECS) based on capacitor-excited asynchronous generator and feeding three-phase four-wire loads. The proposed controller consists of three single-phase insulated gate bipolar junction transistor (IGBT)-based voltage source converters (VSCs) and a battery at dc link. These three single-phase VSCs are connected to each phase of

Bhim Singh; Gaurav Kumar Kasal

2008-01-01

144

Measurement of cylinder diameter by using sinusoidally vibrating sinusoidal gratings  

NASA Astrophysics Data System (ADS)

We propose a new method for measuring a position of an endpoint of a metal cylinder in which a sinusoidal intensity distribution vibrating sinusoidally is used. The position of the endpoint is measured as a phase of a sinusoidally phase- modulated signal which is generated from a light diffracted from the endpoint. In order to extend the measurement range and measure a diameter of a metal cylinder two sinusoidal intensity distributions with two different periods of P1equals100 micrometers and P2equals98 micrometers are used. Cylinder diameters are exactly determined from the measurements for two endpoints of a cylinder using the two periods. Experimental results make it clear that the measurement error is less than 0.3 micrometers for a cylinder metal of 3885.2 micrometers diameter.

Sasaki, Osami; Hashimoto, Kazunori; Fujimori, Yuuji; Suzuki, Takamasa

2001-05-01

145

Steering car-like systems with trailers using sinusoids  

Microsoft Academic Search

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

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

1992-01-01

146

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

SciTech Connect

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.

Cronin, M.J.

1984-07-31

147

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

SciTech Connect

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.

Cronin, M. J.

1985-10-15

148

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

Microsoft Academic Search

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,

Sidney Bell; Jason Sung

1997-01-01

149

Fine structure of hepatic sinusoids and sinusoidal cells in disease.  

PubMed

Liver sinusoids are special capillaries that are limited by fenestrated endothelial cells, without a genuine basement membrane, surrounded by perisinusoidal cells storing vitamin A, and harbouring Kupffer cells and pit cells, resident macrophages, and large granular lymphocytes, respectively. Each nonparenchymal cell and parenchymal cell of the liver interacts with all others and with the extracellular matrix. Therefore, the functional ability of each cell is constantly being modified by the metabolic activity of the others. Human liver biopsies (132), needle or surgical, perfusion-fixed with glutaraldehyde and processed for transmission electron microscopy (TEM), and occasionally for scanning electron microscopy (SEM), were examined. The study included liver diseases (such as alcoholic liver diseases, benign and malignant liver tumors, cholestasis of various origins, fulminant hepatitis, acute rejection after orthotopic liver transplantation, Budd-Chiari syndrome), as well as general or extrahepatic diseases (such as diabetes, hemochromatosis, hypervitaminosis A, various hematological disorders), and normal controls. Ultrastructural abnormalities are described and illustrated under two different headings: 1) elementary lesions of sinusoidal cells (endothelial, Kupffer, perisinusoidal and pit cells), nonsinusoidal cells (in the space of Disse and/or in the lumen), the extracellular matrix; and 2) the major pathological entities including perisinusoidal fibrosis, capillarization of sinusoids, sinusoidal dilatation, and peliosis. In the discussion, an overview of the major abnormalities reported in the literature is presented, and some specific questions regarding 1) perisinusoidal fibrosis in liver with normal histology, 2) the overload of perisinusoidal cells with lipids in non-hypervitaminosis A intoxication and 3) the etiological relationship of sinusoidal dilatation, peliosis, perisinusoidal fibrosis, or sinusoidal tumors with drugs and toxic compounds are discussed. In the event that lesions are not specific to any diagnosis, the knowledge of the ultrastructure of sinusoids is extremely useful from the perspective of the liver as an ecosystem. PMID:2338589

Le Bail, B; Bioulac-Sage, P; Senuita, R; Quinton, A; Saric, J; Balabaud, C

1990-03-01

150

Investigation on Capacitor Voltage Regulation in Cascaded H-Bridge Multilevel Converters With Fundamental Frequency Switching  

Microsoft Academic Search

Multilevel power electronic converters have gained popularity in high-power applications due to their lower switch voltage stress and modularity. Cascaded H-bridge converters are a promising breed of multilevel converters which generally require several separate dc voltage sources. By utilizing the redundant switching states, it is possible to replace the separate dc voltage sources with capacitors and keep only the one

Hossein Sepahvand; Jingsheng Liao; Mehdi Ferdowsi

2011-01-01

151

Robust feedforward compensation scheme with AC booster for high frequency low voltage buck DC–DC converters  

Microsoft Academic Search

Today and in the future, high frequency low voltage DC–DC converters are an effective power-management solution for fast transient\\u000a response and small profile in portable electronic systems. This paper presents a robust feedforward compensation scheme with\\u000a AC booster. An ac amplifier is added in parallel with the main path to compensate the high-frequency gain reduction, which\\u000a improves gain-bandwidth (GBW) product

Chunming Zhang; Zhibiao Shao

152

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

SciTech Connect

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.

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

153

Dust charge and ion drag forces in a high-voltage, capacitive radio frequency sheath  

SciTech Connect

The charge of an isolated dust grain and ion drag forces on the grain in a collisionless, high-voltage, capacitive rf sheath are studied theoretically. The studies are carried out assuming that the positive ions are monoenergetic, as well as in more realistic approximation, assuming that the time-averaged energy distribution of ions impinging on the dust grain has a double-peaked hollow profile. For the nonmonoenergetic case, an analytical expression for the ion flux to the dust grain is obtained. It is studied how the dust charge and ion drag forces depend on the rf frequency, electron density at plasma-sheath boundary, electron temperature and ratio of the effective oscillation amplitude of rf current to the electron Debye length. It is shown that the dust charge and ion drag forces obtained in the monoenergetic ion approximation may differ from those calculated assuming that the ions are nonmonoenergetic. The difference increases with increasing the width of the ion energy spread in the ion distribution.

Denysenko, I.; Azarenkov, N. A. [School of Physics and Technology, V. N. Karazin Kharkiv National University, 4 Svobody sq., 61077 Kharkiv (Ukraine); Ostrikov, K. [CSIRO Materials Science and Engineering, Lindfield, New South Wales 2070 (Australia) and Plasma Nanoscience, School of Physics, University of Sydney, Sydney, New South Wales 2006 (Australia)

2009-11-15

154

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

SciTech Connect

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.

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

155

BIDIRECTIONAL DC-AC CONVERTERS WITH HIGH FREQUENCY ISOLATION  

Microsoft Academic Search

For applications such as UPSs (uninterrupt- ible power supplies) and new energy systems, e.g photo- voltaic or fuel cell systems, it is essential to isolate the load or the photovoltaic cells from the grid. For these applications, the use of a converter that has high frequency isolation and also provides sinusoidal voltage would be very advantageous, since it would eliminate

R. L. Cardoso; I. Barbi

156

The operation of the electrooptical modulator of a magnetograph at low frequencies. I - Control voltage instability  

NASA Astrophysics Data System (ADS)

The topology of high-voltage pulse generator (HPG) circuits designed to control electrooptical modulators of polarized radiation in solar magnetographs is examined. A modified HPG circuit with multiple control which has been tested at the Sayan Observatory is described. The modification is based on the use of a high-voltage pulsed transistor.

Markov, V. S.; Osak, B. F.

157

Radio-frequency powered glow discharge device and method with high voltage interface  

SciTech Connect

A high voltage accelerating potential, which is supplied by a high voltage direct current power supply, is applied to the electrically conducting interior wall of an RF powered glow discharge cell. The RF power supply desirably is electrically grounded, and the conductor carrying the RF power to the sample held by the probe is desirably shielded completely excepting only the conductor's terminal point of contact with the sample. The high voltage DC accelerating potential is not supplied to the sample. A high voltage capacitance is electrically connected in series between the sample on the one hand and the RF power supply and an impedance matching network on the other hand. The high voltage capacitance isolates the high DC voltage from the RF electronics, while the RF potential is passed across the high voltage capacitance to the plasma. An inductor protects at least the RF power supply, and desirably the impedance matching network as well, from a short that might occur across the high voltage capacitance. The discharge cell and the probe which holds the sample are configured and disposed to prevent the probe's components, which are maintained at ground potential, from bridging between the relatively low vacuum region in communication with the glow discharge maintained within the cell on the one hand, and the relatively high vacuum region surrounding the probe and cell on the other hand. The probe and cell also are configured and disposed to prevent the probe's components from electrically shorting the cell's components.

Duckworth, Douglas C. (Knoxville, TN); Marcus, R. Kenneth (Clemson, SC); Donohue, David L. (Vienna, AT); Lewis, Trousdale A. (Oak Ridge, TN)

1994-01-01

158

Energy conversion and performance of switched-voltage control based on negative capacitance with arbitrary switching frequency  

NASA Astrophysics Data System (ADS)

In semi-active synchronized switch damping (SSD) approaches for structural vibration control, the damping effect is achieved by properly switching the voltage on the piezoelectric actuators. In this study, the energy conversion of a synchronized switch damping system based on negative capacitance (SSDNC) with an arbitrary switching frequency is investigated theoretically and validated numerically. First, the model of a general SSDNC system with an arbitrary switching frequency is presented. The general expression of the switched voltage on the piezoelectric actuator is derived. Next, the average converted energy per vibration cycle was derived for arbitrary switching frequency. The results show that the efficiency of energy conversion is reduced by about one half even if the switching frequency deviates slightly from the optimal frequency, which is similar to the SSDI control system. However, the control performance of SSDNC is better than that of SSDI for most non-optimal switching frequencies. Finally, the general expression of control performance of a SSDNC control system for a specific mode is derived and a numerical example is given to support the theoretical results.

Ji, Hongli; Qiu, Jinhao; Xia, Pinqi; Nie, Hong

2012-12-01

159

Radio frequency glow discharge source with integrated voltage and current probes used for evaluation of discharge parameters  

NASA Astrophysics Data System (ADS)

A radio frequency (rf) Grimm-type glow discharge source for the chemical analysis of solid samples, with integrated voltage and current probes, was developed. All elements of a plasma equivalent circuit are determined from the measured current-voltage characteristics. The procedure is based on the independent evaluation of the ion current and electron current region. The physical meaning of the parameters is investigated by comparisons with measurements from dc glow discharges. We found that the reduced rf current of the powered electrode is comparable to the reduced current in dc discharges. A formula is developed that corrects the reduced current due to gas heating. The sheath thickness at the powered rf electrode is evaluated and is between 75 and 1100 ?m. The voltage of the bulk plasma is in the range 2-15 V, and the resistance is between 30 and 400 ?. The bulk plasma consumes about 3% of the total power, and the reduced voltage is comparable to the reduced electrical field in the positive column of direct current discharges. The sheath voltage at the grounded electrode is in the range 25-100 V, the capacities are between 10 and 400 pF, and the resistances are in the range 100 ?-5000 ?. We also found invariants for the evaluated sheath parameters.

Wilken, L.; Hoffmann, V.; Wetzig, K.

2006-03-01

160

Radio-frequency powered glow discharge device and method with high voltage interface  

DOEpatents

A high voltage accelerating potential, which is supplied by a high voltage direct current power supply, is applied to the electrically conducting interior wall of an RF powered glow discharge cell. The RF power supply desirably is electrically grounded, and the conductor carrying the RF power to the sample held by the probe is desirably shielded completely excepting only the conductor's terminal point of contact with the sample. The high voltage DC accelerating potential is not supplied to the sample. A high voltage capacitance is electrically connected in series between the sample on the one hand and the RF power supply and an impedance matching network on the other hand. The high voltage capacitance isolates the high DC voltage from the RF electronics, while the RF potential is passed across the high voltage capacitance to the plasma. An inductor protects at least the RF power supply, and desirably the impedance matching network as well, from a short that might occur across the high voltage capacitance. The discharge cell and the probe which holds the sample are configured and disposed to prevent the probe's components, which are maintained at ground potential, from bridging between the relatively low vacuum region in communication with the glow discharge maintained within the cell on the one hand, and the relatively high vacuum region surrounding the probe and cell on the other hand. The probe and cell also are configured and disposed to prevent the probe's components from electrically shorting the cell's components.

Duckworth, Douglas C. (Knoxville, TN); Marcus, R. Kenneth (Clemson, SC); Donohue, David L. (Vienna, AT); Lewis, Trousdale A. (Oak Ridge, TN)

1994-01-01

161

Effect of voltage and cyclic AMP on frequency of slow-wave-type action potentials in canine colon smooth muscle.  

PubMed Central

1. A non-L-type calcium conductance is involved in the generation of the initial part of the slow-wave-type action potential in colonic smooth muscle. The present study addresses the question whether this conductance is voltage or metabolically activated. 2. Current-induced hyperpolarization increased frequency and amplitude of slow waves measured in Krebs solution. 3. The upstroke potential was 'isolated' from the slow wave by superfusion with 'glucamine-nitrendipine' Krebs solution (NaCl was replaced by glucamine, nitrendipine was added). 4. Hyperpolarization up to -100 mV did not affect the upstroke potential frequency and increased its amplitude. Only hyperpolarization further than -100 mV decreased the frequency less than or equal to 20%, and reduced the amplitude less than or equal to 20%. 5. Depolarization did not affect the upstroke potential frequency. 6. Forskolin, but not 1,9-dideoxyforskolin dramatically decreased the upstroke potential frequency, without affecting other parameters including the resting membrane potential. 7. The effect of forskolin was mimicked by dibutyryl cyclic AMP, 8-bromo-cyclic AMP and 3-isobutyl-1-methylxanthine (IBMX), but not extracellular cyclic AMP. 8. The upstroke potential could not be evoked by depolarizing pulses after inhibition of activity by forskolin. 9. The effect of forskolin could be reversed by the calcium ionophore A23187. 10. In summary, voltage changes up to -40 mV and down to -100 mV do not, but changes in intracellular cyclic AMP do affect the frequency of the upstroke potential. 11. It is likely that intracellular metabolic activity, which may include cyclic AMP but not a voltage change, activates the conductance responsible for the generation of the upstroke potential.

Huizinga, J D; Farraway, L; Den Hertog, A

1991-01-01

162

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

Microsoft Academic Search

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

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

2009-01-01

163

The application of frequency\\/voltage coordinating control strategy to 9-phase hybrid stepping motor driving system  

Microsoft Academic Search

A single phase equivalent circuit and its parameters for a 9-phase hybrid stepping motor are derived, which is based on the structural properties and the stepping motor mathematical model. The motor power\\/angle characteristics can be obtained from the circuit representation of the stepping motor and the synchronous machine theory. According to the requirements for the pull-out torque\\/speed characteristics, frequency\\/voltage coordinating

Dianguo Xu; Yan Wang; Wei Wang

1994-01-01

164

System for Stabilizing the Magnitude and Frequency of Voltages in a Micro Hydroelectric Power Plant with Asymmetric Ballast Regulation  

Microsoft Academic Search

Regulation of the electric power generated by an autonomous electric-supply system fed from a micro hydroelectric plant (microHEP) using an additional ballast load is an effective means of stabilizing the magnitude and frequency of its voltages.Power that can be diffused in ballast can be regulated using thyristor phase-regulating devices or thyristor keys that commutate a set of ballast resistances in

B. V. Lukutin; E. B. Shandarova

2001-01-01

165

DC-bus voltage control for hybrid 4-port high frequency parallel-connected sustainable energy conversion system  

Microsoft Academic Search

In this paper, a performance analysis of a dc-bus voltage control for hybrid parallel-connected sustainable energy conversion system is presented. The hybrid system is the combination of fuel cell (FC), wind turbine, and battery storage via a common dc-bus. These hybrid sources are interfaced to dc- bus through high frequency-based power converters. The main advantages of the proposed topologies are:

Mahmoud M. Amin; Osama A. Mohammed

2011-01-01

166

Improved frequency\\/voltage converters for fast quartz crystal microbalance applications  

Microsoft Academic Search

The monitoring of frequency changes in fast quartz crystal microbalance (QCM) applications is a real challenge in today's instrumentation. In these applications, such as ac electrogravimetry, small frequency shifts, in the order of tens of hertz, around the resonance of the sensor can occur up to a frequency modulation of 1 kHz. These frequency changes have to be monitored very

R. Torres; J. V. García; A. Arnau; H. Perrot; L. To Thi Kim; C. Gabrielli

2008-01-01

167

A medium frequency transformer with multiple secondary windings for medium voltage converter based wind turbine power generating systems  

NASA Astrophysics Data System (ADS)

Recent advances in magnetic materials have led to the development of compact and light weight, medium and high frequency transformers, which would be a possible solution to reducing the size and weight of wind turbine power generating systems. This paper presents the overall design and analysis of a Metglas amorphous alloy 2605SA1 based medium frequency transformer to generate the isolated balanced multiple DC supplies for medium voltage converter systems. A comprehensive electromagnetic analysis is conducted on the proposed design based on experimental results. The test stand, data analysis, and test results are discussed.

Islam, Md Rabiul; Guo, Youguang; Zhu, Jianguo

2013-05-01

168

Stimulated neutrino transformation with sinusoidal density profiles  

NASA Astrophysics Data System (ADS)

Large amplitude oscillations between the states of a quantum system can be stimulated by sinusoidal external potentials with frequencies that are similar to the energy level splitting of the states or a fraction thereof. Situations where the applied frequency is equal to an integer fraction of the energy level splittings are known as parametric resonances. We investigate this effect for neutrinos both analytically and numerically for the case of arbitrary numbers of neutrino flavors. We look for environments where the effect may be observed and find that supernovae are the one realistic possibility due to the necessity of both large densities and large amplitude fluctuations. The comparison of numerical and analytical results of neutrino propagation through a model supernova reveals that it is possible to predict the locations and strengths of the stimulated transitions that occur.

Kneller, J. P.; McLaughlin, G. C.; Patton, K. M.

2013-05-01

169

A Current-Mode Buck DC-DC Converter with Frequency Characteristics Independent of Input and Output Voltages Using a Quadratic Compensation Slope  

NASA Astrophysics Data System (ADS)

By using a quadratic compensation slope, a CMOS current-mode buck DC-DC converter with constant frequency characteristics over wide input and output voltage ranges has been developed. The use of a quadratic slope instead of a conventional linear slope makes both the damping factor in the transfer function and the frequency bandwidth of the current feedback loop independent of the converter's output voltage settings. When the coefficient of the quadratic slope is chosen to be dependent on the input voltage settings, the damping factor in the transfer function and the frequency bandwidth of the current feedback loop both become independent of the input voltage settings. Thus, both the input and output voltage dependences in the current feedback loop are eliminated, the frequency characteristics become constant, and the frequency bandwidth is maximized. To verify the effectiveness of a quadratic compensation slope with a coefficient that is dependent on the input voltage in a buck DC-DC converter, we fabricated a test chip using a 0.18µm high-voltage CMOS process. The evaluation results show that the frequency characteristics of both the total feedback loop and the current feedback loop are constant even when the input and output voltages are changed from 2.5V to 7V and from 0.5V to 5.6V, respectively, using a 3MHz clock.

Sai, Toru; Sugimoto, Yasuhiro

170

Improved Transient and Steady-State Performances of Series Resonant ZCS High-Frequency Inverter-Coupled Voltage Multiplier Converter with Dual Mode PFM Control Scheme  

NASA Astrophysics Data System (ADS)

The A variety of switched-mode high voltage DC power supplies using voltage-fed type or current-fed type high-frequency transformer resonant inverters using MOS gate bipolar power transistors; IGBTs have been recently developed so far for a medical-use X-ray high power generator. In general, the high voltage high power X-ray generator using voltage-fed high frequency inverter with a high voltage transformer link has to meet some performances such as (i) short rising period in start transient of X-ray tube voltage (ii) no overshoot transient response in tube voltage, (iii) minimized voltage ripple in periodic steady-state under extremely wide load variations and filament heater current fluctuation conditions of the X-ray tube. This paper presents two lossless inductor snubber-assisted series resonant zero current soft switching high-frequency inverter using a diode-capacitor ladder type voltage multiplier called Cockcroft-Walton circuit, which is effectively implemented for a high DC voltage X-ray power generator. This DC high voltage generator which incorporates pulse frequency modulated series resonant inverter using IGBT power module packages is based on the operation principle of zero current soft switching commutation scheme under discontinuous resonant current and continuous resonant current transition modes. This series capacitor compensated for transformer resonant power converter with a high frequency transformer linked voltage boost multiplier can efficiently work a novel selectively-changed dual mode PFM control scheme in order to improve the start transient and steady-state response characteristics and can completely achieve stable zero current soft switching commutation tube filament current dependent for wide load parameter setting values with the aid of two lossless inductor snubbers. It is proved on the basis of simulation and experimental results in which a simple and low cost control implementation based on selectively-changed dual-mode PFM for high-voltage X-ray DC-DC power converter with a voltage multiplier strategy has some specified voltage pattern tracking voltage response performances under rapid rising time and no overshoot in start transient tube voltage as well as the minimized steady-state voltage ripple in tube voltage.

Chu, Enhui; Gamage, Laknath; Ishitobi, Manabu; Hiraki, Eiji; Nakaoka, Mutsuo

171

Adaptive notch filtering for the retrieval of sinusoids in noise  

Microsoft Academic Search

In this paper, an adaptive notch filter is developed (employing a frequency domain and time domain analysis) for the enhancement and tracking of sinusoids in additive noise, colored or white. The notch filter is implemented as a constrained infinite impulse response filter with the constraint enforced by a single parameter termed the debiasing parameter. The resulting notch filter requires few

D. V. Bhaskar Rao; Sun-Yuan Kung

1984-01-01

172

Exploiting the Sparsity of the Sinusoidal Model Using Compressed Sensing for Audio Coding  

Microsoft Academic Search

Audio signals are represented via the sinusoidal model as a summation of a small number of sinusoids. This approach introduces sparsity to the audio signals in the frequency domain, which is exploited in this paper by applying Compressed Sensing (CS) to this sparse representation. CS allows sampling of signals at a much lower rate than the Nyquist rate if they

Anthony Griffin; Christos Tzagkarakis; Toni Hirvonen; Panagiotis Tsakalides

2009-01-01

173

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

PubMed

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

Zhang, Ming; Surles, James G

2008-05-28

174

30 Dorados & the Sinusoidal Potential  

NASA Astrophysics Data System (ADS)

The sinusoidal potential is an alternative to the Newtonian potential. In this alternative, the potential of a point mass is ?= -(GM/r) Cos[kor], where ko = 2?/ ?o and ?o is determined empirically to be Ro/20, Ro=8 kpc. A parallel modification to electromagnetism has also been suggested ?=-(Q/r) Exp -[kor] (Bartlett 2004). Recently an equivalent absolute value for ko has been posited: ko2= ?G (? 2 me) 4 c/ (h-bar)3. The sinusoidal potential has been developed in presentations at many recent meetings of the AAS & the DDA. Generally, short-range structure (galaxies and smaller) are dominated by gravitation; long-range (clusters of galaxies and larger) by electromagnetism. 30 Dorados is still a puzzle. Why should this region of intense star formation be between the Large Magellanic Cloud and the Milky Way, but much closer to the former than the latter. Why should its size be roughly 400 pc? What is its connection to the Magellanic Stream? The sinusoidal potential may help.

Bartlett, David F.; Cumalat, J. P.

2011-05-01

175

Impedances of large capacity batteries and cells to audio frequency ac signal voltage  

Microsoft Academic Search

The capacitative behavior of various batteries toward ac signals on connected lines was studied by forcing ac currents at selected frequencies from 10 Hz to 20 kHz through them with a power amplifier. The smaller batteries exhibited some capacitative behavior at low frequencies and changed to inductors as the frequencies were increased. A very large sealed lead-acid battery did not

R. L. Hodgson; H. Oman

1984-01-01

176

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

Microsoft Academic Search

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

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

1999-01-01

177

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

Microsoft Academic Search

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

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

2008-01-01

178

Current—voltage characteristics of lead zirconate titanate/nickel bilayered hollow cylindrical magnetoelectric composites  

NASA Astrophysics Data System (ADS)

Current-voltage measurements obtained from lead zirconate titanate/nickel bilayered hollow cylindrical magnetoelectric composite showed that a sinusoidal current applied to the copper coil wrapped around the hollow cylinder circumference induces voltage across the lead zirconate titanate layer thickness. The current-voltage coefficient and the maximum induced voltage in lead zirconate titanate at 1 kHz and resonance (60.1 kHz) frequencies increased linearly with the number of the coil turns and the applied current. The resonance frequency corresponds to the electromechanical resonance frequency. The current-voltage coefficient can be significantly improved by optimizing the magnetoelectric structure geometry and/or increasing the number of coil turns. Hollow cylindrical lead zirconate titanate/nickel structures can be potentially used as current sensors.

Pan, De-An; Zhang, Shen-Gen; Tian, Jian-Jun; Sun, Jun-Sai; Alex, Volinsky A.; Qiao, Li-Jie

2010-02-01

179

Phase Shift of a Coplanar Waveguide by Bias Voltage on Thick Lead Zirconate Titanate Film at Microwave Frequency  

NASA Astrophysics Data System (ADS)

A coplanar waveguide was fabricated by depositing a 1-?m-thick Au film on a multilayer dielectric, consisting of a 2-?m-thick lead zirconate titanate (PZT) film over an Al2O3 substrate, through etching. Following this, the reflection constant, transmission constant, and phase variation were measured for this transmission line as bias voltage was varied from 30 to 50 V. As a result, it was confirmed that the phase variation becomes about 15° at a 50 V bias at a frequency of 10 GHz. We then confirmed the basic input-output characteristics of this type of structure in the microwave band. Finally, the relative permittivity of a PZT thick film as a coplanar waveguide was estimated using the measurement results of relative permittivity according to the split cavity resonator method, and phase variation under the condition in which a bias voltage was applied.

Shibata, Kouji; Iijima, Takashi; Masuda, Yoichiro

2008-09-01

180

Monitoring Voltage-Dependent Charge Displacement of Shaker B-IR K+ Ion Channels Using Radio Frequency Interrogation  

PubMed Central

Here we introduce a new technique that probes voltage-dependent charge displacements of excitable membrane-bound proteins using extracellularly applied radio frequency (RF, 500 kHz) electric fields. Xenopus oocytes were used as a model cell for these experiments, and were injected with cRNA encoding Shaker B-IR (ShB-IR) K+ ion channels to express large densities of this protein in the oocyte membranes. Two-electrode voltage clamp (TEVC) was applied to command whole-cell membrane potential and to measure channel-dependent membrane currents. Simultaneously, RF electric fields were applied to perturb the membrane potential about the TEVC level and to measure voltage-dependent RF displacement currents. ShB-IR expressing oocytes showed significantly larger changes in RF displacement currents upon membrane depolarization than control oocytes. Voltage-dependent changes in RF displacement currents further increased in ShB-IR expressing oocytes after ?120 µM Cu2+ addition to the external bath. Cu2+ is known to bind to the ShB-IR ion channel and inhibit Shaker K+ conductance, indicating that changes in the RF displacement current reported here were associated with RF vibration of the Cu2+-linked mobile domain of the ShB-IR protein. Results demonstrate the use of extracellular RF electrodes to interrogate voltage-dependent movement of charged mobile protein domains — capabilities that might enable detection of small changes in charge distribution associated with integral membrane protein conformation and/or drug–protein interactions.

Dharia, Sameera; Rabbitt, Richard D.

2011-01-01

181

A low-cost approach for measuring electrical conductivity and relative permittivity of liquids by triangular waveform voltage at low frequencies  

Microsoft Academic Search

We present a novel low-cost experimental method for measuring the electrical conductivity and relative permittivity of liquids at low frequencies. Based on the different relationship between the resistive and capacitive currents with an applied voltage, the resistance and capacitance of fluid test cell can be obtained independently from different time regions of a triangular waveform voltage (TWV). The electrical conductivity

Jianping Wu; J. P. W. Stark

2005-01-01

182

Voltage and frequency stabilizer based on Fuzzy logic control for three-level NPC converters in stand-alone wind energy systems  

Microsoft Academic Search

The paper proposes a Fuzzy logic approach for controlling three-level NPC converters in stand alone wind energy systems. A key function of this controller is to maintain constant voltage and frequency for customers while maintaining smooth voltage waveform with less filtering requirements. The principle of the proposed Fuzzy controller is based on a modified PI approach in which the error

Ameen Gargoom; Abu Mohammad Osman Haruni; M. E. Haque; M. Negnevitsky

2010-01-01

183

Human exposure to power frequency electric and magnetic fields inside a very high voltage power station  

Microsoft Academic Search

The paper presents the electric and magnetic fields distribution at steady-state operation in a very recently rehabilitated 400\\/220 kV voltage power station, taking into account the on-site equipments arrangement. The experimental measurement values are compared with the public and professional electromagnetic field exposure limits imposed by the EU 2004\\/40\\/EC Directive and by the local legislation. Colour maps of the electric

Calin Munteanu; l. T. Pop; Ciprian Diaconu; M. Ilia

2007-01-01

184

Control of plasma process by use of harmonic frequency components of voltage and current  

DOEpatents

The present invention provides for a technique for taking advantage of the intrinsic electrical non-linearity of processing plasmas to add additional control variables that affect process performance. The technique provides for the adjustment of the electrical coupling circuitry, as well as the electrical excitation level, in response to measurements of the reactor voltage and current and to use that capability to modify the plasma characteristics to obtain the desired performance.

Miller, Paul A. (Albuquerque, NM); Kamon, Mattan (Cambridge, MA)

1994-01-01

185

Ciliary frequency and orientational responses to clamped voltage steps in Paramecium  

Microsoft Academic Search

Summary 1.Simultaneous voltage clamping and microcinematography were used to examine the behavior of cilia in response to prolonged hyperpolarizing and depolarizing steps in the membrane potential ofParamecium caudatum. In the absence of stimulation the cilia beat at less than 20 cycles per second with the power stroke directed toward the posterior and somewhat to the right (i.e. 4 o'clock) of

Hans Machemer; Roger Eckert

1975-01-01

186

Innovative electromagnetic induction eddy current-based dual packs heater using voltage-fed high-frequency PWM resonant inverter for continuous fluid processing in pipeline  

Microsoft Academic Search

This paper presents an innovative electromagnetic induction-heated fluid heating appliance using voltage-fed quasi-resonant zero voltage soft switching (ZVS)-PWM high frequency inverter, which operates under the variable power constant frequency (VPCF) regulation strategy. This appliance includes various features as compared with conventional gas contribution type and sheathed heater type fluid heating; rapid heating, clean heating, high efficiency and so on. This

M. Kaneda; S. Hishikawa; T. Tamaka; B. Guo; M. Nakaoka

1999-01-01

187

A novel non-fragile single-loop voltage and frequency controller for induction generator based isolated renewable energy conversion system  

Microsoft Academic Search

Poor voltage and frequency regulation under source and load perturbations limit the use of self excited induction generator (SEIG) in isolated and dispersed generation, which can exploit wind\\/microhydro type renewable energy sources. In the present work, a Generalized Impedance Controller (GIC), which is a pulse-width-modulated voltage-source-inverter with a dc-link battery, is used to regulate both, amplitude and frequency of the

J. K. Chatterjee; Priyesh J. Chauhan

2010-01-01

188

Modeling and mitigation of dynamic load beat-frequency oscillation in multiphase voltage regulators with high-gain peak current control scheme  

Microsoft Academic Search

High-frequency dynamic load may cause phase current oscillation in multiphase interleaved voltage regulators. A model is presented in this paper to investigate this phenomenon in the recently reported high-gain peak current control (HGPCC) voltage regulators. Based on the analysis, it is concluded that HGPCC scheme suffers from beat-frequency oscillation problems, similarly to conventional peak current control scheme. A modified HGPCC

Chen-Hua Chiu; Dan Chen; Ching-Jan Chen; Wei-Hsu Chang

2010-01-01

189

Measurement of Radiated Electromagnetic Field due to Low Voltage ESD with Spherical Electrode in 1-3GHz Frequency Bandwidth  

NASA Astrophysics Data System (ADS)

The micro-gap discharge as the low voltage ESD shows very fast transition-duration of about 32 ps or less. Furthermore, the breakdown field strength in the gap was very high of about 80 MV/m in low voltage discharging of below 400V. The relationship between the breakdown field strength in the gap and the amplitude of radiated electromagnetic field was examined in experimental study. The amplitude of radiated electromagnetic field was proportion to the breakdown field strength at the gap in the resonance experimental system using the discharge electrode with dipole configuration. In this time, we present an improved experimental system to measure the amplitude of radiated electromagnetic filed in more wideband region using spherical electrodes and a horn antenna. As a result, the amplitude of radiated electromagnetic field is proportion to the discharge voltage from 300V to 620V, and the amplitude of radiated electromagnetic field was according to the diameter of spherical electrode in 1-3GHz frequency bandwidth.

Kawamata, Ken; Minegishi, Shigeki; Fujiwara, Osamu

190

Voltage Control of the Resonance Frequency of Dielectric Electroactive Polymer (DEAP) Membranes  

Microsoft Academic Search

We report on the characterization, active tuning, and modeling of the first mode resonance frequency of dielectric electroactive polymer (DEAP) membranes. Unlike other resonance frequency tuning techniques, the tuning procedure presented here requires no external actuators or variable elements. Compliant electrodes were sputtered or implanted on both sides of 20-35-mum-thick and 2-4-mm-diameter polydimethylsiloxane membranes. The electrostatic force from an applied

Philippe Dubois; Samuel Rosset; Muhamed Niklaus; Massoud Dadras; Herbert Shea

2008-01-01

191

A fiber-optic current sensor with frequency-codified output for high-voltage systems  

Microsoft Academic Search

The authors present a frequency-output fiber-optic current sensor for high-power systems. The sensor exploits the magnetostriction of the ferromagnetic core of a standard current transformer, which is interrogated by a length of single-mode fiber coiled onto it and a Mach-Zehnder interferometer. The deformation of the core due to the magnetic field generated by the current produces a frequency-modulated output signal.

P. Perez-Millan; L. Martinez-Leon; A. Diez; J. L. Cruz; M. V. Andres

2002-01-01

192

Voltage dependence of subthreshold resonance frequency in layer II of medial entorhinal cortex  

PubMed Central

The resonance properties of individual neurons in entorhinal cortex 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 due to depolarizing input from neurons coding velocity. To test for potential changes in intrinsic frequency we measured the resonance properties of neurons at different membrane potentials in neurons in medial and lateral entorhinal cortex. In medial entorhinal neurons the resonant frequency of individual neurons decreased in a linear manner as the membrane potential was depolarized between ?70 and ?55 mV. At more hyperpolarized membrane potentials, cells asymptotically approached a maximum resonance frequency. Consistent with previous studies, near resting potential the cells of the medial EC possessed a decreasing gradient of resonance frequency along the dorsal to ventral axis, and cells of the lateral EC lacked resonant properties regardless of membrane potential or position along the medial to lateral axis within lateral EC. Application of 10 µM ZD7288, the H-channel blocker, abolished all resonant properties in MEC cells, and resulted in physiological properties very similar to lateral EC cells. These results on resonant properties show a clear change in frequency response with depolarization that could contribute to generation of grid cell firing properties in the medial entorhinal cortex.

Shay, Christopher F.; Boardman, Ian S.; James, Nicholas M.; Hasselmo, Michael E.

2012-01-01

193

Sinusoidal Response of a Thin Viscoplastic Plate with Severe Temperature Gradient.  

National Technical Information Service (NTIS)

A mathematical model for the sinusoidal vibratory response of a thin plate subjected to a through the thickness temperature gradient is developed. An 85% copper/15% niobium composite plate was modeled using a temperature and frequency dependent model of t...

K. J. Fischer

1990-01-01

194

High-voltage nanosecond pulses in a low-pressure radio-frequency discharge.  

PubMed

An influence of a high-voltage (3-17 kV) 20 ns pulse on a weakly-ionized low-pressure (0.1-10 Pa) capacitively coupled radiofrequency (RF) argon plasma is studied experimentally. The plasma evolution after pulse exhibits two characteristic regimes: a bright flash, occurring within 100 ns after the pulse (when the discharge emission increases by 2-3 orders of magnitude over the steady-state level), and a dark phase, lasting a few hundreds ?s (when the intensity of the discharge emission drops significantly below the steady-state level). The electron density increases during the flash and remains very large at the dark phase. 1D3V particle-in-cell simulations qualitatively reproduce both regimes and allow for detailed analysis of the underlying mechanisms. It is found that the high-voltage nanosecond pulse is capable of removing a significant fraction of plasma electrons out of the discharge gap, and that the flash is the result of the excitation of gas atoms, triggered by residual electrons accelerated in the electric field of immobile bulk ions. The secondary emission from the electrodes due to vacuum UV radiation plays an important role at this stage. High-density plasma generated during the flash provides efficient screening of the RF field (which sustains the steady-state plasma). This leads to the electron cooling and, hence, onset of the dark phase. PMID:23848787

Pustylnik, M Y; Hou, L; Ivlev, A V; Vasilyak, L M; Couëdel, L; Thomas, H M; Morfill, G E; Fortov, V E

2013-06-10

195

High-voltage nanosecond pulses in a low-pressure radio-frequency discharge  

NASA Astrophysics Data System (ADS)

An influence of a high-voltage (3-17 kV) 20 ns pulse on a weakly-ionized low-pressure (0.1-10 Pa) capacitively coupled radiofrequency (RF) argon plasma is studied experimentally. The plasma evolution after pulse exhibits two characteristic regimes: a bright flash, occurring within 100 ns after the pulse (when the discharge emission increases by 2-3 orders of magnitude over the steady-state level), and a dark phase, lasting a few hundreds ?s (when the intensity of the discharge emission drops significantly below the steady-state level). The electron density increases during the flash and remains very large at the dark phase. 1D3V particle-in-cell simulations qualitatively reproduce both regimes and allow for detailed analysis of the underlying mechanisms. It is found that the high-voltage nanosecond pulse is capable of removing a significant fraction of plasma electrons out of the discharge gap, and that the flash is the result of the excitation of gas atoms, triggered by residual electrons accelerated in the electric field of immobile bulk ions. The secondary emission from the electrodes due to vacuum UV radiation plays an important role at this stage. High-density plasma generated during the flash provides efficient screening of the RF field (which sustains the steady-state plasma). This leads to the electron cooling and, hence, onset of the dark phase.

Pustylnik, M. Y.; Hou, L.; Ivlev, A. V.; Vasilyak, L. M.; Couëdel, L.; Thomas, H. M.; Morfill, G. E.; Fortov, V. E.

2013-06-01

196

Improvement to speech-music discrimination using sinusoidal model based features  

Microsoft Academic Search

This paper addresses a model-based audio content analysis for classification of speech-music mixed audio signals into speech\\u000a and music. A set of new features is presented and evaluated based on sinusoidal modeling of audio signals. The new feature\\u000a set, including variance of the birth frequencies and duration of the longest frequency track in sinusoidal model, as a measure\\u000a of the

Jalil Shirazi; Shahrokh Ghaemmaghami

2010-01-01

197

Frequency-dependent reduction of voltage-gated sodium current modulates retinal ganglion cell response rate to electrical stimulation  

NASA Astrophysics Data System (ADS)

The ability to elicit visual percepts through electrical stimulation of the retina has prompted numerous investigations examining the feasibility of restoring sight to the blind with retinal implants. The therapeutic efficacy of these devices will be strongly influenced by their ability to elicit neural responses that approximate those of normal vision. Retinal ganglion cells (RGCs) can fire spikes at frequencies greater than 200 Hz when driven by light. However, several studies using isolated retinas have found a decline in RGC spiking response rate when these cells were stimulated at greater than 50 Hz. It is possible that the mechanism responsible for this decline also contributes to the frequency-dependent 'fading' of electrically evoked percepts recently reported in human patients. Using whole-cell patch clamp recordings of rabbit RGCs, we investigated the causes for the spiking response depression during direct subretinal stimulation of these cells at 50-200 Hz. The response depression was not caused by inhibition arising from the retinal network but, instead, by a stimulus-frequency-dependent decline of RGC voltage-gated sodium current. Under identical experimental conditions, however, RGCs were able to spike at high frequency when driven by light stimuli and intracellular depolarization. Based on these observations, we demonstrated a technique to prevent the spiking response depression.

Tsai, David; Morley, John W.; Suaning, Gregg J.; Lovell, Nigel H.

2011-10-01

198

Analysis of event-related potentials (ERP) by damped sinusoids.  

PubMed

Several researchers propose that event-related potentials (ERPs) can be explained by a superposition of transient oscillations at certain frequency bands in response to external or internal events. The transient nature of the ERP is more suitable to be modelled as a sum of damped sinusoids. These damped sinusoids can be completely characterized by four sets of parameters, namely the amplitude, the damping coefficient, the phase and the frequency. The Prony method is used to estimate these parameters. In this study, the long-latency auditory-evoked potentials (AEP) and the auditory oddball responses (P300) of 10 healthy subjects are analysed by this method. It is shown that the original waveforms can be reconstructed by summing a small number of damped sinusoids. This allows for a parsimonious representation of the ERPs. Furthermore, the method shows that the oddball target responses contain higher amplitude, slower delta and slower damped theta components than those of the AEPs. With this technique, we show that the differentiation of sensory and cognitive potentials are not inherent in their overall frequency content but in their frequency components at certain bands. PMID:9711822

Demiralp, T; Ademoglu, A; Istefanopulos, Y; Gülçür, H O

1998-06-01

199

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

Microsoft Academic Search

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)

Drazen Dujic; Gabriele Grandi; Martin Jones; Emil Levi

2008-01-01

200

Microcontroller-based full control of ultrasonic motor with frequency and voltage adjusting  

Microsoft Academic Search

In this study, PIC16F628 microcontroller-based control of a traveling-wave ultrasonic motor has been implemented. A drive system including power supply, power electronic drives, and interface electronic circuits have been designed. The microcontroller has been integrated with drive system to achieve overall control of ultrasonic motor. Microcontroller generates start\\/stop, direction, and speed\\/position control signals for the motor drive system. Driving frequency

Erdal Bekiroglu

2008-01-01

201

Frequency and temperature dependences of capacitance-voltage characteristics of InGaN/GaN light-emitting structures with multiple quantum wells  

SciTech Connect

A frequency dependence of capacitance-voltage (C-V) characteristics in multiple quantum well InGaN/GaN heterostructures in the range of 60 Hz-5 MHz is investigated at temperatures from 77 to 300 K. It is found that temperature lowering and test frequency increase lead to the similar changes in obtained apparent carrier distributions. It is shown that commonly used conditions for capacitance-voltage profiling of InGaN/GaN LEDs correspond to an intermediate case between low- and high-frequency capacitance approximations. At all temperatures investigated, the edge low-frequency capacitance-voltage profiles are experimentally reached and found to be identical. The process of attainment of equilibrium of the charges in the active region is most likely determined by tunneling of the carriers through the barriers.

Soltanovich, O. A. [Russian Academy of Sciences, Institute of Microelectronic Technology and High-Purity Materials (Russian Federation); Shmidt, N. M. [Russian Academy of Sciences, Ioffe Physical Technical Institute (Russian Federation); Yakimov, E. B., E-mail: yakimov@iptm.ru [Russian Academy of Sciences, Institute of Microelectronic Technology and High-Purity Materials (Russian Federation)

2011-02-15

202

All-polymer modulator for high frequency low drive voltage applications  

NASA Astrophysics Data System (ADS)

As EO phase modulators become more prevalent components in optical and RF applications, the demand increases for high bandwidth and low drive voltage modulators that can easily be integrated into developing photonic technologies. The proposed paper will discuss a device architecture for a phase modulator based on a recently developed organic EO material (OEOM), IKD-1-50 integrated into a PMMA polymer host, using a low-index, photo-curable resin as the cladding layers all on a Si platform. Designs for a TM waveguide and electrode configuration will be presented from theory and modeling, through fabrication to characterization. The EO material serving as the core of the waveguide is poled using a poling stage and monitoring apparatus with same electrodes designed for modulation. Poling procedures have been optimized for this material based on experimentation in simple slab-capacitor characterization devices, and produce in-device r33 values that are comparable with attenuated total internal reflection measurements. The challenges presented by the instability of OEOMs in common processing conditions have been addressed and a very simple fabrication process has been developed using standard photolithography and reactive ion etching to define an inverted ridge waveguide structure, pattern surrounding electrodes, and prepare usable end facets. Phase modulator characterization results for fabricated and poled devices have been quantified and will be presented. The simplicity of this device architecture on a Si handle allows for integration into various photonic applications.

Eng, David L. K.; Kozacik, Stephen; Olbricht, Benjamin C.; Shi, Shouyuan; Prather, Dennis W.

2013-03-01

203

Induction Motor Operation With Non-Sinusoidal Impressed Voltages  

Microsoft Academic Search

The usual procedure in considering the operation of induction motors has been to neglect the effect of harmonics. Although in most instances this gives results which are sufficiently accurate, the question of how much these effects are or how much is being neglected has yet to be answered in electrical engineering literature. In this paper an attempt is made to

L. A. Doggett; E. R. Queer

1929-01-01

204

AUTOMATIC CALIBRATION OF SINUSOIDAL ENCODER SIGNALS  

Microsoft Academic Search

Precision positioning and manipulation systems often rely on data from sensors delivering a sinusoidal signal pair. These signals can be interpolated to provide a high resolution measurement. The paper presents a novel method for removing signal difierences and drifts by automatic self-calibrating the sinusoidal signal pair. Then, manual calibration is avoided and slow varying efiects, like thermal drifts or imprecise

Silvano Balemi

2005-01-01

205

A New Initial-Rotor-Position Estimation Method for SPM Synchronous Motors Using Spatially Rotating High-Frequency Voltage  

NASA Astrophysics Data System (ADS)

First of all, this paper proposes a new dynamic mathematical model of surface-mounted permanent magnet synchronous motors (SPMSMs) with flux saturation phenomena, in stationary reference frame. Secondly, based on the dynamic model, this paper establishes new dynamic simulators taking flux saturation phenomena into account, which act as very powerful tools for developing initial-rotor-position estimation methods for SPMSMs. Thirdly, this paper proposes a new initial-rotor-position estimation method for SPMSMs. The proposed method is so simple that it inputs a spatially rotating high-frequency voltage to SPMSMs, measures current output and can estimate directly rotor position of N-pole through norm evaluation of the current. The method exploits flux saturation phenomena inherent to SPMSMs and is insensitive to all motor parameters. According to experiments, the maximum estimation error is about ±0.035(rad) (±2(degree)) in mechanical sense, which is comparable to sensor mounting error and is sufficient small for initial drive of SPMSMs.

Shinnaka, Shinji; Kumakura, Takeshi

206

High frequency eddy current-based far infrared rays radiant heater using zero voltage soft switching inverter with asymmetrical PWM implementation  

Microsoft Academic Search

This paper presents an innovative electromagnetic induction eddy current heated type far infrared rays radiant heater using the voltage-fed edge-resonant ZVS-PWM high frequency inverter for food cooking and processing. Its operating principle is described. Its operating performances such as the voltage and current peak stress. soft switching condition, and power regulation are illustrated on the based of duty cycle time

H. Iyomori; K. Ogura; H. Muraoka; A. Okuno; E. Hiraki; M. Nakaoka

2002-01-01

207

Propulsion by sinusoidal locomotion: A motion inspired by Caenorhabditis elegans  

NASA Astrophysics Data System (ADS)

Sinusoidal locomotion is commonly seen in snakes, fish, nematodes, or even the wings of some birds and insects. This doctoral thesis presents the study of sinusoidal locomotion of the nematode C. elegans in experiments and the application of the state-space airloads theory to the theoretical forces of sinusoidal motion. An original MATLAB program has been developed to analyze the video records of C. elegans' movement in different fluids, including Newtonian and non-Newtonian fluids. The experimental and numerical studies of swimming C. elegans has revealed three conclusions. First, though the amplitude and wavelength are varying with time, the motion of swimming C. elegans can still be viewed as sinusoidal locomotion with slips. The average normalized wavelength is a conserved character of the locomotion for both Newtonian and non-Newtonian fluids. Second, fluid viscosity affects the frequency but not the moving speed of C. elegans, while fluid elasticity affects the moving speed but not the frequency. Third, by the resistive force theory, for more elastic fluids the ratio of resistive coefficients becomes smaller. Inspired by the motion of C. elegans and other animals performing sinusoidal motion, we investigated the sinusoidal motion of a thin flexible wing in theory. Given the equation of the motion, we have derived the closed forms of propulsive force, lift and other generalized forces applying on the wing. We also calculated the power required to perform the motion, the power lost due to the shed vortices and the propulsive efficiency. These forces and powers are given as functions of reduced frequency k, dimensionless wavelength z, dimensionless amplitude A/b, and time. Our results show that a positive, time-averaged propulsive force is produced for all k>k0=pi/ z. At k=k0, which implies the moment when the moving speed of the wing is the same as the wave speed of its undulation, the motion reaches a steady state with all forces being zero. If there were no shed vorticity effects, the propulsive force would be zero at z = 0.569 and z = 1.3 for all k, and for a fixed k the wing would gain the optimal propulsive force when z = 0.82. With the effects of shed vorticity, the propulsive efficiency decreases from 1.0 to 0.5 as k goes to infinity, and the propulsive efficiency increases almost in a linear relationship with k0.

Ulrich, Xialing

208

A Voltage Controlled Oscillator for a Phase-Locked Loop Frequency Synthesizer in a Silicon-on-Sapphire Process  

SciTech Connect

Engineers from a government-owned engineering and manufacturing facility were contracted by government-owned research laboratory to design and build an S-band telemetry transmitter using Radio Frequency Integrated Circuit (RFIC) technology packaged in a Low-Temperature Co-fired Ceramic (LTCC) Multi-Chip Module. The integrated circuit technology chosen for the Phase-Locked Loop Frequency Synthesizer portion of the telemetry transmitter was a 0.25 um CMOS process that utilizes a sapphire substrate and is fabricated by Peregrine Semiconductor corporation. This thesis work details the design of the Voltage Controlled Oscillator (VCO) portion of the PLL frequency synthesizer and constitutes an fully integrated VCO core circuit and a high-isolation buffer amplifier. The high-isolation buffer amplifier was designed to provide 16 dB of gain for 2200-3495 MHz as well as 60 dB of isolation for the oscillator core to provide immunity to frequency pulling due to RF load mismatch. Actual measurements of the amplifier gain and isolation showed the gain was approximately 5 dB lower than the simulated gain when all bond-wire and test substrate parasitics were taken into account. The isolation measurements were shown to be 28 dB at the high end of the frequency band but the measurement was more than likely compromised due to the aforementioned bond-wire and test substrate parasitics. The S-band oscillator discussed in this work was designed to operate over a frequency range of 2200 to 2300 MHz with a minimum output power of 0 dBm with a phase-noise of -92 dBc/Hz at a 100 kHz offset from the carrier. The tuning range was measured to be from 2215 MHz to 2330 MHz with a minimum output power of -7 dBm over the measured frequency range. A phase-noise of -90 dBc was measured at a 100 kHz offset from the carrier.

Garrison, Sean

2009-05-21

209

Frequency-dependent reliability of spike propagation is function of axonal voltage-gated sodium channels in cerebellar purkinje cells.  

PubMed

The spike propagation on nerve axons, like synaptic transmission, is essential to ensure neuronal communication. The secure propagation of sequential spikes toward axonal terminals has been challenged in the neurons with a high firing rate, such as cerebellar Purkinje cells. The shortfall of spike propagation makes some digital spikes disappearing at axonal terminals, such that the elucidation of the mechanisms underlying spike propagation reliability is crucial to find the strategy of preventing loss of neuronal codes. As the spike propagation failure is influenced by the membrane potentials, this process is likely caused by altering the functional status of voltage-gated sodium channels (VGSC). We examined this hypothesis in Purkinje cells by using pair-recordings at their somata and axonal blebs in cerebellar slices. The reliability of spike propagation was deteriorated by elevating spike frequency. The frequency-dependent reliability of spike propagation was attenuated by inactivating VGSCs and improved by removing their inactivation. Thus, the functional status of axonal VGSCs influences the reliability of spike propagation. PMID:23775547

Yang, Zhilai; Wang, Jin-Hui

2013-12-01

210

On the frequency dispersion of the capacitance-voltage behavior of epitaxial Ge on Si p+-n junctions  

NASA Astrophysics Data System (ADS)

The electrically active defects in epitaxial germanium layers grown selectively on silicon-shallow trench isolation (STI) wafers have been investigated by means of p+-n junction characterization. The main focus is on the capacitance-voltage (C-V) analysis in reverse operation. A pronounced frequency dispersion in the C-V characteristics has been found for Ge Si-STI layers, while this is not the case for thick epitaxial Ge on Si layers, which contain a significantly lower density of threading dislocations. It is shown that the apparent free carrier density profile derived from the C-V plot at high frequency exhibits a pronounced overshoot in the vicinity of the Ge-Si heterointerface. However, this feature is not only determined by the band offset between the Ge and Si conduction band edges but also by the high density of extended defects and associated deep levels present near the interface. Finally, the impact of a postgrowth high-temperature annealing on the electrical properties of Ge Si-STI epitaxial layers will be discussed in view of the resulting change in extended defect density and profile.

Yang, R.; Eneman, G.; Wang, G.; Claeys, C.; Simoen, E.

2009-10-01

211

Sinusoidal and Delta Function Responses of Visual Cells of the Limulus Eye  

PubMed Central

Dynamic responses of visual cells of the Limulus eye to stimuli of sinusoids and narrow pulses of light superimposed on a nonzero mean level have been obtained. Amplitudes and phase angles of averaged sinusoidal generator potential are plotted with respect to frequency of intensity modulation for different mean levels of light adaptation. At frequencies above 10 CPS, generator potential amplitudes decrease sharply and phase lag angle increases. At frequencies below 1 CPS, amplitude decreases. A maximum of amplitude in the region of 1 to 2 CPS is apparent with increased mean intensity. The generator potential responses are compared with those of differential equation models. Variation of gain with mean intensity for incremental stimuli is consistent with logarithmic sensitivity of the photoreceptor. Frequency response of the photoreceptor derived from narrow pulses of light predicts the frequency response obtained with sinusoidal stimuli, and the photoreceptor is linear for small signals in the light-adapted state.

Pinter, R. B.

1966-01-01

212

A magnetic device current injection in a three-phase sinusoidal-current utility interface  

Microsoft Academic Search

A magnetic device for current injection in a three-phase, sinusoidal-current utility interface is presented. This class of sinusoidal rectification depends on the injection of a third-harmonic current into the AC side of a three-phase rectifier. The injection network should provide a low and equal impedance in each of the three branches to the modulation current at the third harmonic frequency,

R. Naik; M. Rastogi; N. Mohan; R. Nilssen; C. P. Henze

1993-01-01

213

Nonlinear systems analysis: comparison of white noise and sum of sinusoids in a biological system.  

PubMed Central

The Gaussian white noise and the sum-of-sinusoids methods of systems analysis provide equivalent descriptions of nearly linear and strongly nonlinear transductions in the cat retina. Smoothness in the frequency domain is a common characteristic of biological transductions. This permits a substantial improvement in the signal-to-noise ratio by using the sum-of-sinusoids method, as is demonstrated for the transductions of the cat retina.

Victor, J D

1979-01-01

214

Rem2-targeted shRNAs reduce frequency of miniature excitatory postsynaptic currents without altering voltage-gated Ca˛? currents.  

PubMed

Ca˛? influx through voltage-gated Ca˛? channels (VGCCs) plays important roles in neuronal cell development and function. Rem2 is a member of the RGK (Rad, Rem, Rem2, Gem/Kir) subfamily of small GTPases that confers potent inhibition upon VGCCs. The physiologic roles of RGK proteins, particularly in the brain, are poorly understood. Rem2 was implicated in synaptogenesis through an RNAi screen and proposed to regulate Ca˛? homeostasis in neurons. To test this hypothesis and uncover physiological roles for Rem2 in the brain, we investigated the molecular mechanisms by which Rem2 knockdown affected synaptogenesis and Ca˛? homeostasis in cultured rat hippocampal neurons. Expression of a cocktail of shRNAs targeting rat Rem2 (rRem2) reduced the frequency of miniature excitatory postsynaptic currents (mEPSCs) measured 10 d after transfection (14 d in vitro), but did not affect mEPSC amplitude. VGCC current amplitude after rRem2-targeted knockdown was not different from that in control cells, however, at either 4 or 10 d post transfection. Co-expression of a human Rem2 that was insensitive to the shRNAs targeting rRem2 was unable to prevent the reduction in mEPSC frequency after rRem2-targeted knockdown. Over-expression of rRem2 resulted in 50% reduction in VGCC current, but neither the mEPSC frequency nor amplitude was affected. Taken together, the observed effects upon synaptogenesis after shRNA treatment are more likely due to mechanisms other than modulation of VGCCs and Ca˛? homeostasis, and may be independent of Rem2. In addition, our results reveal a surprising lack of contribution of VGCCs to synaptogenesis during early development in cultured hippocampal neurons. PMID:21980534

Wang, Hong-Gang; Wang, Chuan; Pitt, Geoffrey S

2011-09-29

215

Frequency dependence of elastic wave speed  

NASA Astrophysics Data System (ADS)

Elastic wave speed is one of the essential rock properties, and it is important for locating earthquake sources and estimating Earth’s structure. Usual seismic records contain up to ~ 10 Hz, whereas elastic wave records from laboratory measurements with rock sample contain the frequency from ~ 100 kHz to ~ 2 MHz. It is unclear whether elastic wave speed is independent of frequency or not. It is important to measure the accurate elastic wave speed over a wide frequency range. In this study, we measure the transmitting wave through a rock sample from 100 kHz to a few MHz, and consider the method to estimate the frequency dependence of elastic wave speed. We prepared a cylindrical granite sample (50 mm in diameter, 100 mm long), and put P-wave type broadband transducers to the both sectional surfaces of sample. We applied one cycle of sinusoidal voltage signal of various frequencies to one of the transducers, and received the transmitting wave through the sample with the other transducer. The transducers were calibrated with a laser Doppler vibrometer (LDV) that can measure the absolute particle velocity of a vibrating plane with a flat sensitivity up to 6 MHz. The method to estimate frequency dependence of elastic wave speed has not been established. One of the reasons is that initial portion of a sinusoidal voltage signal rises gradually, so that it contains other frequency contents than a frequency of input sinusoidal wave. The other reason is that later phases than the initial phase contain scattering waves. To avoid these problems, we analyzed the frequency dependence of traveltime for the first peak or other phases in the first cycle.

Kawakata, H.; Doi, I.; Yoshimitsu, N.

2010-12-01

216

Spur-Reduced Digital Sinusoid Synthesis.  

National Technical Information Service (NTIS)

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...

M. J. Flanagan G. A. Zimmerman

1993-01-01

217

Radio frequency glow discharge source with integrated voltage and current probes used for sputtering rate and emission yield measurements at insulating samples.  

PubMed

Radio frequency glow discharge optical emission spectroscopy (RF-GD-OES) is routinely used for the chemical analysis of solid samples. Two independent electrical signals from the discharge are required for quantification. When sputtering insulating samples, the voltage over the discharge is not directly measurable. The coupling capacity of the sample is required in order to calculate the discharge voltage. A procedure is outlined where the coupling capacity is determined using an electrical measurement without discharge. The calculated time-dependent discharge voltage and current are evaluated using a plasma equivalent circuit. An insulating sample is sputtered at constant cathode voltage and current. The emission yield for an aluminium line is comparable to that of conducting reference material. PMID:15952004

Wilken, L; Hoffmann, V; Wetzig, K

2005-10-19

218

Readily implemented enhanced sinusoid detection in noise  

NASA Astrophysics Data System (ADS)

Significant efforts have been devoted, spanning many years, to the problem of sinusoid detection in noise. Many of these efforts have produced superb, yet complex, algorithms which may be difficult to use for a wide segment of the Digital Signal Processing (DSP) community. This paper presents a simple, easily implemented and highly effective method which solves this problem. This method severely degrades non-sinusoidal noise while leaving the embedded sinusoid(s) relatively undisturbed. The algorithm, simply put, exploits the difference between the net effect of integration and differentiation of sinusoids versus the effect of these operations on random noise and other signal sequences. The cross-correlation of sine wave with its differentiated (and/or integrated) self is quite high. Conversely, the cross-reduction of a noise sequence with its differentiated (and/or integrated) self is much lower. Therefore, it is reasonable to assume that for sequences consisting of a sinusoid in noise, significant signal-to-noise-ratios (SNRs) in the correlation results are achievable using a combination of differentiation (and/or integration) and cross-correlation operations on such sequences. This technique has been applied to actual Doppler radar data, as well as to synthesized data, with excellent improvement in signal detection capability.

Lindsay, K. V.

1992-03-01

219

Combined resonant tank capacitance and pulse frequency modulation control for ZCS-SR inverter-fed high voltage DC power supply  

NASA Astrophysics Data System (ADS)

Conventional pulse frequency modulated (PFM) zero current switching (ZCS) series resonant (SR) inverter fed high voltage dc power supplies have nearly zero switching loss. However, they have limitations of poor controllability at light loads and large output voltage ripple at low switching frequencies. To address these problems, this paper proposes a combined resonant tank capacitance and pulse frequency modulation based control approach. For the realization of the proposed control approach, the tank circuit of the resonant inverter is made up of several resonant capacitors that are switched into or out of the tank circuit by electromechanical switches. The output voltage of the converter is regulated by digitally modulating the resonant tank capacitance and narrowly varying the switching frequency. The proposed control scheme has several features, namely a wide range of controllability even at light loads, less output voltage ripple, and less current stress on the inverter's power switches at light loads. Therefore, the proposed control approach alleviates most of the problems associated with conventional PFM. Experimental results obtained from a scaled down laboratory prototype are presented to verify the effectiveness of the proposed system.

Lee, S. S.; Iqbal, S.; Kamarol, M.

2011-09-01

220

Low-output and high-input impedance frequency filters using universal voltage conveyor for High-Speed Data Communication Systems  

Microsoft Academic Search

Modern network technology puts all the time bigger demands on the properties of continuous-time filters. In particule, wide bandwidth applications are required. We can find new active elements which operate on higher frequencies compared with commonly used active elements in many new applications. These are, for example, current or voltage conveyors. In this paper a new building block of analog

Martin Minarcik; Kamil Vrba

2006-01-01

221

Drop-on-demand hybrid printing using a piezoelectric MEMS printhead at various waveforms, high voltages and jetting frequencies  

NASA Astrophysics Data System (ADS)

In this paper, electrohydrodynamic jetting is investigated in order to print ultra-fine dots and lines in drop-on-demand (DOD) mode, using micro-electromechanical system-based printhead with a piezoelectric actuator. In such hybrid system, jetting ultra-fine droplets in DOD mode, without applying an extremely high-voltage pulse, is possible as the meniscus is first disturbed by a piezoelectric actuator and the droplet is ejected by the applied electric field. As the amplitude of the drive waveform of the piezoelectric actuator is varied, droplets with volumes of 3.4 to 46.8 pL are realized. As the amplitude of the electric field is increased, the ejected droplets lengthen and at 8 kV, thin elliptical dots are printed. Although changing the jetting frequency from 0.1 to 2.0 kHz resulted in volume reduction from 9.4 pL down to 2.9 pL, the DOD characteristic is well maintained throughout. Such hybrid jetting characteristics enable the generation of diverse patterns in the printed electronics area.

Kim, Young-Jae; Kim, Sangjin; Hwang, Jungho; Kim, Yong-Jun

2013-06-01

222

A radio frequency/high voltage pulse generator for the operation of a planar multipole ion trap/time-of-flight mass spectrometer  

NASA Astrophysics Data System (ADS)

We present a radio frequency (RF)/high voltage pulse generator designed to provide suitable waveforms for the operation of a planar multipole ion trap/time-of-flight mass spectrometer. Our generator supplies a RF signal to two pairs of trapping electrodes, allowing ions to be stored in between them. Subsequently, the RF is rapidly switched off and high voltage extraction pulses are applied to the trap electrodes in order to obtain a time-of-flight spectrum of the stored ions. The quenching of the RF and the extraction pulses are synchronized to the RF phase, ensuring well-defined ejection conditions.

Marmillod, Philippe; Antonioni, Severino; Lorenz, Ulrich J.

2013-04-01

223

Lissajous figures of glow and filamentary dielectric barrier discharges under high frequency voltage at atmospheric pressure in helium  

Microsoft Academic Search

Dielectric barrier discharges (DBD) under 11.87 kHz voltages were carried out in helium or air at atmospheric pressure. Applied voltage and current pulses, Lissajous figures were measured, and discharge images were taken by ICCD in an exposure time of ns orders. Lissajous figures of glow and filamentary DBDs were investigated. The results show that the mode at the inception of

Yanpeng Hao; Jianyang Chen; Lin Yang; Xiaolei Wang

2009-01-01

224

PhET Teacher Ideas & Activities: Applications of Sinusoidal Functions  

NSDL National Science Digital Library

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.

Sokolowski, Andrzej

225

Fine-Grained Dynamic Voltage and Frequency Scaling for Precise Energy and Performance Trade-Off Based on the Ratio of Off-Chip Access to On-Chip Computation Times  

Microsoft Academic Search

This paper presents an intra-process dynamic voltage and frequency scaling (DVFS) technique targeted toward non real-time applications running on an embedded system platform. The key idea is to make use of runtime information about the external memory access statistics in order to perform CPU voltage and frequency scaling with the goal of minimizing the energy consumption while translucently controlling the

Kihwan Choi; Ramakrishna Soma; Massoud Pedram

2004-01-01

226

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  

NASA Astrophysics Data System (ADS)

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 kV/1 A pulses with 5 ?s width, 10 kHz repetition rate, with less than 1 ?s pulse rise time. Experimental results for resistive loads are presented and discussed.

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

2007-03-01

227

Measuring adaptation with a sinusoidal perturbation function  

PubMed Central

We examine the possibility that sensory and motor adaptation may be induced via a sinusoidally incremented perturbation. This sinewave adaptation method provides superior data for fitting a parametric model than when using the standard step-function method of perturbation, due to the relative difficulty of fitting a decaying exponential vs. a sinusoid. Using both experimental data and simulations, we demonstrate the difficulty of detecting the presence of motor adaptation using a step-function perturbation, compared to detecting motor adaptation using our sinewave perturbation method.

Hudson, Todd E.; Landy, Michael S.

2013-01-01

228

Digital camera resolution measurement using sinusoidal Siemens stars  

NASA Astrophysics Data System (ADS)

The resolution of a digital camera is defined as its ability to reproduce fine detail in an image. To test this ability methods like the Slanted Edge SFR measurement developed by Burns and Williams1 and standardized in ISO 122332 are used. Since this method is - in terms of resolution measurements - only applicable to unsharpened and uncompressed data an additional method described in this paper had to be developed. This method is based on a Sinusoidal Siemens Star which is evaluated on a radius by radius or frequency by frequency basis. For the evaluation a freely available runtime program developed in MATLAB is used which creates the MTF of a camera system as the contrast over the frequency.

Loebich, Christian; Wueller, Dietmar; Klingen, Bruno; Jaeger, Anke

2007-03-01

229

Flyback battery equalizer with voltage doubler rectifier  

Microsoft Academic Search

In this paper, a new flyback battery equalizer employing a voltage doubler rectifier is proposed. The proposed circuit transfers electric charges by utilizing the resonance between the transformer leakage inductor and secondary capacitor. Therefore, the proposed battery equalizer can reduce the switch turn off loss and snubber loss by a sinusoidal shaped current. Furthermore, the voltage stress on the rectifier

Hyoung-Suk Kim; Ki-Bum Park; Hyun-Wook Seong; Gun-Woo Moon; Myung-Joong Youn

2011-01-01

230

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

SciTech Connect

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.

None

2012-01-23

231

High Step-Up DC-DC Converters Using Zero-Voltage Switching Boost Integration Technique and Light-Load Frequency Modulation Control  

Microsoft Academic Search

This paper describes nonisolated high step-up DC-DC converters using zero voltage switching (ZVS) boost integration technique (BIT) and their light-load frequency modulation (LLFM) control. The proposed ZVS BIT integrates a bidirectional boost converter with a series output module as a parallel-input and series-output (PISO) configuration. It provides many advantages such as high device utilization, high step-up capability, power and thermal

Hyun-Wook Seong; Hyoung-Suk Kim; Ki-Bum Park; Gun-Woo Moon; Myung-Joong Youn

2012-01-01

232

A Generic Open-Loop Algorithm for Three-Phase Grid Voltage\\/Current Synchronization With Particular Reference to Phase, Frequency, and Amplitude Estimation  

Microsoft Academic Search

This paper presents a new open-loop architecture for three-phase grid synchronization based on moving average and predictive filters, where accurate measurements of phase, frequency, and amplitude are carried out in real time. Previous works establish that the fundamental positive sequence vector of a set of utility voltage\\/current vectors can be decoupled using Park's transformation and low-pass filters. However, the filtering

Francisco D. Freijedo; JesÚs Doval-Gandoy; Óscar LÓpez; Enrique Acha

2009-01-01

233

Riding the Ferris Wheel: A Sinusoidal Model  

ERIC Educational Resources Information Center

|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…

Mittag, Kathleen Cage; Taylor, Sharon E.

2011-01-01

234

Scattering by a Sinusoidally Stratified Half Space.  

National Technical Information Service (NTIS)

A detailed investigation of the scattering of a plane wave incident on a periodically-stratified medium is presented. The periodic medium occupies the x > 0 region, and the stratification occurs along the z direction and is produced by a sinusoidal modula...

T. Tamir H. C. Wang

1966-01-01

235

Spur-reduced digital sinusoid synthesis  

Microsoft Academic Search

This paper presents and analyzes a technique for reducing the spurious signal content in digital sinusoid synthesis. Spur reduction is accomplished through dithering amplitude and phase values prior to wordlength 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 wordlength reduction without introducing additional

Michael J. Flanagan; George A. Zimmerman

1995-01-01

236

SH Wave Scattering from a Sinusoidal Grating.  

National Technical Information Service (NTIS)

A good way to test discrete wave number modeling techniques is to model scattering from a sinusoidal free surface, while varying the maximum slope of the interface. Four discrete wavenumber methods, the Aki-Larner, the Waterman, the Waterman-Fourier, and ...

H. D. Axilrod J. F. Ferguson

1989-01-01

237

Outer Solar System and the Sinusoidal Potential  

Microsoft Academic Search

At recent meetings of the AAS I have presented posters defending a new, sinusoidal gravitational potential. Here the customary numerator in Newton's law is replaced by GM cos(2pi r\\/lambda o) where lambda o is a universal constant, 425 pc. Because there are 20 oscillations of the potential between the sun and the center of the Milky Way, galactic tidal forces

D. F. Bartlett

2003-01-01

238

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)

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.

Tunç, T.; Gökçen, M.; Uslu, ?.

2012-11-01

239

Voltage harmonic control of Z-source inverter for UPS applications  

Microsoft Academic Search

This paper presents a control method for obtaining sinusoidal output voltage regardless of the nonlinear and unbalanced loads. Control of the DC boost stage and capacitor voltage is presented. The resonant regulators are used for selective harmonic cancellation of the output AC voltage. The Z-source inverter is able to provide higher AC voltage related to the DC link voltage than

Arkadiusz Kulka; Tore Undeland

2008-01-01

240

Simultaneous Reactive-Power and Frequency Estimations Using Simple Recursive WLS Algorithm and Adaptive Filtering  

Microsoft Academic Search

A new simple approach to the design of digital algo- rithm for simultaneous reactive-power and frequency estimations of local system is presented. The algorithm is derived using the weighted-least-square method. During the algorithm derivation, a pure sinusoidal voltage model was assumed. Cascade finite- impulse-response (FIR) comb digital filters are used to minimize the noise effect and to eliminate the presence

Miodrag D. Kušljevi? Kusljevic; Predrag D. Poljak

2011-01-01

241

High-Frequency Loss Calculation in a Smooth Rotor Induction Motor Using FEM  

Microsoft Academic Search

In this paper, a new approach for the calculation of high-frequency losses in induction motors is presented. The input to the motors is assumed to be supplied from a sinusoidal voltage source. The method is based on the two-dimensional (2-D) field solutions of the magnetic circuit, obtained by using a nonlinear ldquoharmonicrdquo solution. Hence, the solution time is very short.

H. BÜlent Ertan; K. Leblebicioglu; B. Avenoglu; Murat Pirgaip

2007-01-01

242

AlGaN/GaN-HEMTs with a breakdown voltage higher than 100 V and maximum oscillation frequency f{sub max} as high as 100 GHz  

SciTech Connect

The N-Al{sub 0.27}Ga{sub 0.73}N/GaN High Electron Mobility Transistors (HEMTs) with different gate lengths L{sub g} (ranging from 170 nm to 0.5 {mu}m) and gate widths W{sub s} (ranging from 100 to 1200 {mu}m) have been studied. The S parameters have been measured; these parameters have been used to determine the current-gain cutoff frequency f{sub t}, the maximum oscillation frequency f{sub max}, and the power gain MSG/MAG and Mason's coefficients were investigated in the frequency range from 10 MHz to 67 GHz in relation to the gate length and gate width. It was found that the frequencies f{sub t} and f{sub max} attain their maximum values of f{sub t} = 48 GHz and f{sub max} = 100 GHz at L{sub g} = 170 nm and W{sub g} = 100 {mu}m. The optimum values of W{sub g} and output power P out of the basic transistors have been determined for different frequencies of operation. It has also been demonstrated that the 170 nm Al{sub 0.27}Ga{sub 0.73}N/GaN HEMT technology provides both good frequency characteristics and high breakdown voltages and is very promising for high-frequency applications (up to 40 GHz)

Mokerov, V. G., E-mail: vgmokerov@yandex.ru; Kuznetsov, A. L.; Fedorov, Yu. V.; Bugaev, A. S.; Pavlov, A. Yu.; Enyushkina, E. N.; Gnatyuk, D. L.; Zuev, A. V.; Galiev, R. R.; Ovcharenko, E. N. [Russian Academy of Sciences, Institute of UHF Semiconductor Electronics (Russian Federation); Sveshnikov, Yu. N. [Elma-Malahit-Concern Energomera (Russian Federation); Tsatsulnikov, A. F.; Ustinov, V. M. [Russian Academy of Sciences, St. Petersburg Physics and Technology Centre for Research and Education (Russian Federation)

2009-04-15

243

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)

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%.

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

2012-04-01

244

An intercomparison of AC voltage using a digitally synthesized source  

Microsoft Academic Search

An AC voltage intercomparison was conducted by the National Institute of Standards and Technology (NIST) to determine the consistency of AC voltage measurements made at various standards laboratories. The transport standard used for this purpose was an NIST-developed, digitally synthesized sinusoidal voltage source whose RMS (root mean square) value was calculated by measuring the DC level of each of the

N. M. Oldham; W. F. Bruce; C. M. Fu; A. Cohee; A. G. Smith

1990-01-01

245

Measurements of stray antenna capacitance in the STEREO/WAVES instrument: Comparison of the radio frequency voltage spectrum with models of the galactic nonthermal continuum spectrum  

NASA Astrophysics Data System (ADS)

The STEREO/WAVES instrument is designed to measure interplanetary radio emission and in situ plasma waves in the solar wind. The instrument uses three orthogonal monopole electric antennas as its sensor system in both a pseudodipole and monopole mode. At high radio frequencies, the capacitance of the antennas determines the system gain. Here we estimate the stray capacitance in the antenna system by comparing the measured voltage spectrum with a model of the galactic continuum spectrum, which is the instrument background at high frequencies. Together with the antenna free-space capacitance, these measurements provide an absolute calibration of the STEREO/WAVES experiment at radio frequencies, a prerequisite for quantitative studies of solar and astrophysical radio emission.

Eastwood, J. P.; Bale, S. D.; Maksimovic, M.; Zouganelis, I.; Goetz, K.; Kaiser, M. L.; Bougeret, J.-L.

2009-08-01

246

Detection of Binary Pulsars with GPU-Accelerated Sinusoidal Hough Transformations  

NASA Astrophysics Data System (ADS)

Analysis of relativistic binary pulsars is currently the best means by which to test theories of gravity in strong gravitational fields. Four-dimensional Hough Transformations can detect sinusoids in noisy images. Hough Transformations can be applied to Dynamic Power Spectra to detect the sinusoidal shift in observed spin frequency from binary pulsars in approximately circular orbits. We present four alternative GPU implementations of a Hough Transformation algorithm, which we apply to synthesized Dynamic Power Spectra data to determine the GPU kernel that provides the best acceleration.

Laidler, C.; Kuttel, M. M.

2013-10-01

247

Accurate frequency estimation at low signal-to-noise ratio  

Microsoft Academic Search

A frequency estimator for sinusoids in white noise is described. Convergence results are obtained for the single sinusoid case and a simulation described for the multiple sinusoid case. The estimator is shown to be capable of providing accurate frequency estimates at lower SNR's than currently existing techniques. Furthermore, the simplicity of the algorithm lends itself to a simple and efficient

S. Kay

1984-01-01

248

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

Microsoft Academic Search

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

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

2001-01-01

249

On some aspects of the high-frequency performance of operational amplifiers and current-to-voltage converters  

Microsoft Academic Search

The standard monolithic operational amplifier current-to-voltage converter will show underdamped second-order response to step inputs. This is not discussed in standard texts. It is shown that the transfer function of the amplifier must be treated as a complex variable in order to understand the response and to apply correct compensation. The response of commercial operational amplifiers is shown to fall

R. N. Caffin

1975-01-01

250

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.

2008-11-24

251

Fine-grained dynamic voltage and frequency scaling for precise energy and performance tradeoff based on the ratio of off-chip access to on-chip computation times  

Microsoft Academic Search

Abstract This paper ,presents ,an intra-process,dynamic ,voltage ,and frequency,scaling (DVFS) technique targeted toward,non real-time applications running on an embedded,system platform. The key idea isto make ,use of runtime ,information ,about the external memory access statistics in order ,to perform ,CPU voltage and ,frequency scaling with the goal of minimizing ,the energy ,consumption ,while translucently controlling the performance ,penalty. The proposed

Kihwan Choi; Ramakrishna Soma; Massoud Pedram

2005-01-01

252

Optical voltage reference  

DOEpatents

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.

Rankin, R.; Kotter, D.

1994-04-26

253

Optical voltage reference  

DOEpatents

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.

Rankin, R.; Kotter, D.

1992-12-31

254

Morphological mechanisms for regulating blood flow through hepatic sinusoids.  

PubMed

This review summarizes what is known about the various morphological sites that regulate the distribution of blood flow to and from the sinusoids in the hepatic microvascular system. These sites potentially include the various segments of the afferent portal venules and hepatic arterioles, the sinusoids themselves, and central and hepatic venules. Given the paucity of smooth muscle in the walls of these vessels, various sinusoidal lining cells have been suggested to play a role in regulating the diameters of sinusoids and influencing the distribution and velocity of blood flow in these vessels. While sinusoidal endothelial cells have been demonstrated to be contractile and to exhibit sphincter function, attention has recently focused on the perisinusoidal stellate cell as the cell responsible for controlling the sinusoidal diameter. A very recent study, however, suggested that the principal site of vasoconstriction elicited by ET-1 was the pre-terminal portal venule. This raised the question of whether or not the diameters of sinusoids might decrease due to passive recoil when inflow is reduced or eliminated and intra-sinusoidal pressure falls. In more recent in vivo microscopic studies, clamping of the portal vein dramatically reduced sinusoidal blood flow as well as the diameters of sinusoids. The sinusoidal lumens rapidly returned to their initial diameters upon restoration of portal blood flow suggesting that sinusoidal blood pressure normally distends the sinusoidal wall which can recoil when the pressure drops. Stellate cells may be responsible for this reaction given the nature of their attachment to parenchymal cells by obliquely oriented microprojections from the lateral edges of their subendothelial processes. This suggests that care must be exercised when interpreting the mechanism for the reduction of sinusoidal diameters following drug administration without knowledge of changes occurring to the portal venous and hepatic inflow. PMID:10726955

McCuskey, R S

2000-02-01

255

VIENNA rectifier II-a novel single-stage high-frequency isolated three-phase PWM rectifier system  

Microsoft Academic Search

Based on an analysis of basic realization possibilities, the structure of the power circuit of a new single-stage three-phase boost-type pulsewidth modulated (PWM) rectifier system (VIENNA Rectifier II) is developed. This system has continuous sinusoidal time behavior of the input currents and high-frequency isolation of the output voltage, which is controlled in a highly dynamic manner. As compared to a

Johann W. Kolar; Uwe Drofenik; Franz C. Zach

1999-01-01

256

Analysis of ladar range resolution enhancement by sinusoidal phase modulation  

NASA Astrophysics Data System (ADS)

The ability of a ladar system to resolve two or more separate returns from a combined echo is related to the effective correlation bandwidth of the pulse emitted by the ladar system. Phase modulation of an outgoing phase introduces additional frequency components, which increases the effective correlation bandwidth of the pulse and thus improves the range resolution of the system. In this paper, we discuss the general theoretical basis for achieving improved range resolution using a modulated waveform and a matched filter receiver. We then demonstrate these concepts by considering the particular case of improved range resolution for a sinusoidally phase modulated carrier with a rectangular amplitude function. We also perform computer simulations with a realistic pulsed ladar envelope possessing the same modulation function. Our calculations indicate that the resolution of a pulsed ladar system may be improved by a factor of 70 with a phase-modulated pulse and a matched-filter receiver.

Masters, Leonard T.; Mark, Martin B.; Duncan, Bradley D.

1995-11-01

257

A digital frequency synthesizer  

Microsoft Academic Search

A digital frequency synthesizer has been designed and constructed based on generating digital samples ofexp [j(2^{pi}nk\\/N)]at timenT. The real and imaginary parts of this exponential form samples of quadrature sinusoids where the frequency indexkis allowed to vary(-N\\/4) leq K < (N\\/4). The digital samples drive digital to analog converters followed by low-pass interpolating filters to produce analog sinusoids. The method

JOSEPH TIERNEY; CHARLES M. RADER; B. Gold

1971-01-01

258

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)

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.

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

259

Takayasu arteritis associated with hepatic sinusoidal dilatation.  

PubMed

Hepatic sinusoidal dilatation (HSD) is pathological entity that is characterized by peliosis hepatis (PH) like lesions, with vascular lesions that consist of multiple cyst-like, blood-filled cavities within the liver. To the best of our knowledge, neither PH nor HSD have been associated with systemic vasculitis. We describe herein two cases of idiopathic HSD associated with Takayasu arteritis (TA), diagnosed at an early stage of vasculitis. The same endothelial target in HSD and TA, and the favorable outcome of HSD with treatment of TA, suggest a pathogenic link between the two diseases. PMID:21911899

Durant, Cécile; Martin, Jérome; Hervier, Baptiste; Gournay, Jérome; Hamidou, Mohamed

260

Surface discharge plasma actuator driven by a pulsed 13.56 MHz-5 kHz voltage waveform  

NASA Astrophysics Data System (ADS)

The effect of incorporating pulses of radio-frequency (rf: 13.56 MHz) voltage into the driving waveform of a surface discharge plasma actuator is investigated. Rf voltage is applied to the actuator to increase the production of ions and thereby increase the thrust that is generated by the discharge. This waveform is coupled to the powered electrode in 5 µs pulses and combined with a relatively low-frequency (LF) 5 kHz sinusoid to form a pulsed 13.56 MHz-5 kHz (rf-LF) driving voltage. Measurements of the applied voltage, rf and LF currents, effective power, and velocity field of the surrounding air are undertaken at atmospheric pressure. The thrust that is generated using the rf-LF waveform is estimated from the velocity fields using a momentum balance and is found to increase for increasing rf voltage when the LF voltage remains constant. Maximum thrust is achieved when the rf pulses are positioned at the LF voltage minima and this suggests the importance of negative ions. The efficacy of rf-LF actuation is investigated by comparing the thrust that is generated per unit increase in peak voltage with that obtained using an LF-driven discharge.

Dedrick, J.; Im, S.; Cappelli, M. A.; Boswell, R. W.; Charles, C.

2013-10-01

261

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

SciTech Connect

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.

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

1996-07-01

262

Comparison of sinusoidal and pulsed-operated dielectric barrier discharges in an O2/N2 mixture at atmospheric pressure  

NASA Astrophysics Data System (ADS)

Experiments on the spatial and temporal structure of the breakdown process of sinusoidal- and pulsed-operated dielectric barrier microdischarges (MDs) are compared. Three different waveforms are considered: a sinusoidal waveform at 20 kHz and pulsed-bipolar and unipolar-voltage profiles at 10 kHz with varying duty cycles (asymmetric pulse). Electrical data and simultaneous streak and iCCD images of individual MDs in dielectric barrier discharges (DBDs) with 1 mm gap in a gas mixture of 0.1 vol% O2 in N2 at atmospheric pressure are recorded. For sinusoidal-operated DBDs there are no significant differences between the MDs at positive and negative half-periods. Sinusoidal operation corresponds to pulsed-bipolar operation with symmetrical pulses, but with lower streamer velocities and different spatio-temporal emission distribution. The development of pulsed-driven MDs is determined by the voltage between both electrodes and not by the polarity of the driven electrode, resulting in nearly the same behavior of bipolar- and unipolar-pulsed-driven MDs. DBDs operated with asymmetric pulses show a significant difference in the spatial structure and in the temporal behavior between the rising and falling slopes of the high voltage pulse.

Kettlitz, M.; Höft, H.; Hoder, T.; Weltmann, K.-D.; Brandenburg, R.

2013-04-01

263

High-speed measurement of free spectral range voltage of tunable filters.  

PubMed

A new technique to measure the frequency response of a fiber-optic tunable filter (TF) is proposed and demonstrated. This technique is based on the linearity of the sinusoidal function in the vicinity of mpi, where m is an integer. The free spectral range (FSR) voltage, V(FSR), is evaluated fast and accurately by measuring the time interval corresponding to the bandwidth of TF. The time interval is obtained by adjusting the dc offset of the driving signal to locate the transmission peak of TF at the maximum slope of the driving signal of <1V(p-p). The measured FSR voltages range from 500 mV to 100 V over the frequency up to 200 kHz. PMID:19109637

Yeh, Yunhae; Park, DoHyun; Park, Se Hoon

2009-01-01

264

A SINGLE PHASE SIX-SWITCH INVERTER WITH TWO FIX AND VARIABLE OUTPUT VOLTAGES  

Microsoft Academic Search

Recent years, a single phase six-switch inverter is introduced as a new DC-AC power conversion converter. To achieve an AC sinusoidal output voltage, a proper switching sequence is produced by voltage and current controllers in two differential and common modes. This paper presents optimal values for voltage and current controllers to achieve a desired AC output voltage with low THD.

Khalil Gorgani Firouzjah; Shokrollah Bahrami Samani; Mohammad Bagher Sharifian; Taraneh Herizchi

265

Development of a 60 Hz Power Standard Using SNS Programmable Josephson Voltage Standards  

Microsoft Academic Search

We are implementing a new standard for 60 Hz power measurements based on precision sinusoidal reference voltages from two independent programmable Josephson voltage standards (PJVS): one for voltage and one for current. The National Institute of Standards and Technology PJVS systems use series arrays of Josephson junctions to produce accurate quantum-based DC voltages. Using stepwise-approximation synthesis, the PJVS systems produce

Samuel P. Benz; Paul D. Dresselhaus; Bryan C. Waltrip; Thomas L. Nelson; Yonuk Chong; Jonathan M. Williams; Dale Henderson; Pravin Patel; Luis Palafox; Ralf Behr

2007-01-01

266

Spur-reduced digital sinusoid synthesis  

NASA Astrophysics Data System (ADS)

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.

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

1993-11-01

267

Probabilistic evaluation of voltage stability  

Microsoft Academic Search

This paper presents a contingency enumeration based approach to evaluate the voltage stability of a power system. The proposed approach, includes the selection and evaluation of contingencies, the classification of contingencies according to selected failure criteria and the accumulation of voltage stability indices. Voltage stability is quantified in the form of indices such as the probability and frequency of voltage

S. Aboreshaid; R. Billinton

1999-01-01

268

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

PubMed Central

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)

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

1983-01-01

269

Damped sinusoidal function to model acute irradiation in radiotherapy patients.  

PubMed

In the paper, we suggest a damped sinusoidal function be used to model a regenerative response of mucosa in time after the radiotherapy treatment. The medical history of 389 RT patients irradiated within the years 1994-2000 at the Radiotherapy Department, Cancer Center, Maria Sk?odowska-Curie Memorial Institute of Oncology, Gliwice, Poland, was taken into account. In the analyzed group of patients, the number of observations of a single patient ranged from 2 to 25 (mean = 8.3, median = 8) with severity determined by use of Dische's scores from 0 to 24 (mean = 7.4, median = 7). Statistical modeling of radiation-induced mucositis was performed for five groups of patients irradiated within the following radiotherapy schedules: CAIR, CB, Manchester, CHA-CHA, and Conventional. All of the regression parameters of the assumed model, i.e. amplitude, damping coefficient, angular frequency, phase of component, and offset, estimated in the analysis were statistically significant (p-value < 0.05) for the radiotherapy schedules. The model was validated using a non-oscillatory function. Following goodness-of-fit statistics, the damped sinusoidal function fits the data better than the non-oscillatory damped function. Model curves for harmonic characteristics with confidence intervals were plotted separately for each of the RT schedules and together in a combined design. The suggested model might be helpful in the numeric evaluation of the RT toxicity in the groups of patients under analysis as it allows for practical comparisons and treatment optimization. A statistical approach is also briefly described in the paper. PMID:23333064

Tukiendorf, Andrzej; Miszczyk, Leszek; Bojarski, Jacek

2013-01-15

270

Derivation of mathematical expressions to define resonant ejection from square and sinusoidal wave ion traps  

NASA Astrophysics Data System (ADS)

Resonant ejection for mass analysis with ion traps is widely used because it markedly improves the mass range and resolution of ion traps. Unfortunately, an easy-to-use analytical expression that defines the ejection mass as a function of the trapping and excitation frequencies is missing in the literature because the secular frequency of the ions in sinusoidal ion traps is not easily determined for all stable values of qz from the Mathieu equation. However, the ion secular frequency for all stable values of qz in digital ion traps can be readily determined from Hill's equation. We have taken this expression and solved it for qz to produce an analytical expression for the ejection mass as a function of trapping and excitation frequency. We also recognized that the expression for the ion mass during resonant ejection for a square wave driven trap can be converted to an expression for a sinusoidal wave trap merely by multiplication by a factor of 4/[pi]. These new expressions open up the possibility of rapid mass calibration for any method of resonant ejection from square or sinusoidal wave driven ion traps.

Koizumi, Hideya; Whitten, William B.; Reilly, Peter T. A.; Koizumi, Eiko

2009-09-01

271

Outer Solar System and the Sinusoidal Potential  

NASA Astrophysics Data System (ADS)

At recent meetings of the AAS I have presented posters defending a new, sinusoidal gravitational potential. Here the customary numerator in Newton's law is replaced by GM cos(2? r/? o) where ? o is a universal constant, 425 pc. Because there are 20 oscillations of the potential between the sun and the center of the Milky Way, galactic tidal forces should be about 120 times as strong as normally believed. Such a large tidal force is needed if the global galactic potential is to explain the surprisingly large modulation in the galactic longitude of the perihelia of comets teased from the Oort cloud. (A modulation with prominent peaks at longitudes of 45,135, Ĺ degrees was first observed by Matese and Whitmire (1996). They now feel that an impactor is the culprit, but it could instead be the sinusoidal potential (Bartlett, AAS-199)). Here I discuss how the same large tidal force might be responsible for two more observations in our solar system. Recently, Shaviv and Veizer (2003) have found a periodicity of about 140 Myrs in the observed isotopic fraction of heavy oxygen (O-18) in terrestrial calcite. They ascribe the period to variations in the cosmic ray rate caused by the revolution of the solar system through 4 rotating spiral arms. I find it rather to be the effect of variations in the strength of the galactic tidal force as the sun rotates in the nearly stationary quadrupole field of the central bar. There is increasing evidence that the Kuiper belt really ends at about 50 AU. (Donnes 1997; Allen, Bernstein, and Molhotra 2001). The cause for this cut-off is unknown, but galactic tidal forces are dismissed. I will show how the new, stronger forces can be effective.

Bartlett, D. F.

2003-12-01

272

Nonlinear dynamics in VCSELs driven by a sinusoidally modulated current and Rössler oscillator  

NASA Astrophysics Data System (ADS)

We firstly investigate the dynamics of vertical-cavity surface-emitting lasers (VCSELs) subject to sinusoidally modulated current using numerical simulations. For a few-hundred MHz frequency of injection current, the VCSELs emit a single pulse or a package of pulses when the injection current fluctuates around the threshold current. By varying the amplitude of the modulation, we show that the width of the bistability hysteresis loop can be suppressed and replaced by smooth single or multiple switching. For a few GHz frequency of injection current, the polarization modes of VCSELs exhibit a period-doubling transition to chaotic behavior. Then by modulating the VCSELs pump current by one of the outputs of a Rössler oscillator, we generate dynamical behaviors found in VCSELs subject to a sinusoidally modulated current. This new way of modulation of semiconductor lasers would bring a general benefit in the physical equipment, and reduce their cost.

Kingni, S. T.; Talla Mbé, J. H.; Woafo, P.

2012-05-01

273

Effects of sinusoidal whole-body vibration on the lumbar spine: the stress-strain relationship  

Microsoft Academic Search

The aim of this experimental study was to estimate the strain in the lumbar spine due to whole-body vibration (WBV). Four male subjects were exposed to vertical sinusoidal WBV with frequencies ranging from 1 to 15 Hz at two intensities (I1 = 1.5 ms-2 rms; I2 = 3.0 ms-2 rms). The compressive forces acting on the disc L3-4 during the

Helmut Seidel; Ralph Bluethner; Barbara Hinz

1986-01-01

274

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

Microsoft Academic Search

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

Ho-En Liao

2005-01-01

275

Application of sliding-mode control to the design of a buck-based sinusoidal generator  

Microsoft Academic Search

This paper is devoted to the design of a sliding-mode control scheme for a buck-based inverter, with programmable amplitude, frequency, and DC offset, with no external sinusoidal reference required. A general procedure for obtaining an autonomous (time independent) switching surface from a time-dependent one is presented. For this surface, the system exhibits a zeroth-order dynamics in sliding motion. On the

Domingo Biel; Enric Fossas; Francisco Guinjoan; Eduard Alarcón; Alberto Poveda

2001-01-01

276

Sinusoidal visuomotor tracking: intermittent servo-control or coupled oscillations?  

PubMed

In visuomotor tasks that involve accuracy demands, small directional changes in the trajectories have been taken as evidence of feedback-based error corrections. In the present study variability, or intermittency, in visuomanual tracking of sinusoidal targets was investigated. Two lines of analyses were pursued: First, the hypothesis that humans fundamentally act as intermittent servo-controllers was re-examined, probing the question of whether discontinuities in the movement trajectory directly imply intermittent control. Second, an alternative hypothesis was evaluated: that rhythmic tracking movements are generated by entrainment between the oscillations of the target and the actor, such that intermittency expresses the degree of stability. In 2 experiments, participants (N = 6 in each experiment) swung 1 of 2 different hand-held pendulums, tracking a rhythmic target that oscillated at different frequencies with a constant amplitude. In 1 line of analyses, the authors tested the intermittency hypothesis by using the typical kinematic error measures and spectral analysis. In a 2nd line, they examined relative phase and its variability, following analyses of rhythmic interlimb coordination. The results showed that visually guided corrective processes play a role, especially for slow movements. Intermittency, assessed as frequency and power components of the movement trajectory, was found to change as a function of both target frequency and the manipulandum's inertia. Support for entrainment was found in conditions in which task frequency was identical to or higher than the effector's eigenfrequency. The results suggest that it is the symmetry between task and effector that determines which behavioral regime is dominant. PMID:11734409

Russell, D M; Sternad, D

2001-12-01

277

Rem2-Targeted shRNAs Reduce Frequency of Miniature Excitatory Postsynaptic Currents without Altering Voltage-Gated Ca2+ Currents  

PubMed Central

Ca2+ influx through voltage-gated Ca2+ channels (VGCCs) plays important roles in neuronal cell development and function. Rem2 is a member of the RGK (Rad, Rem, Rem2, Gem/Kir) subfamily of small GTPases that confers potent inhibition upon VGCCs. The physiologic roles of RGK proteins, particularly in the brain, are poorly understood. Rem2 was implicated in synaptogenesis through an RNAi screen and proposed to regulate Ca2+ homeostasis in neurons. To test this hypothesis and uncover physiological roles for Rem2 in the brain, we investigated the molecular mechanisms by which Rem2 knockdown affected synaptogenesis and Ca2+ homeostasis in cultured rat hippocampal neurons. Expression of a cocktail of shRNAs targeting rat Rem2 (rRem2) reduced the frequency of miniature excitatory postsynaptic currents (mEPSCs) measured 10 d after transfection (14 d in vitro), but did not affect mEPSC amplitude. VGCC current amplitude after rRem2-targeted knockdown was not different from that in control cells, however, at either 4 or 10 d post transfection. Co-expression of a human Rem2 that was insensitive to the shRNAs targeting rRem2 was unable to prevent the reduction in mEPSC frequency after rRem2-targeted knockdown. Over-expression of rRem2 resulted in 50% reduction in VGCC current, but neither the mEPSC frequency nor amplitude was affected. Taken together, the observed effects upon synaptogenesis after shRNA treatment are more likely due to mechanisms other than modulation of VGCCs and Ca2+ homeostasis, and may be independent of Rem2. In addition, our results reveal a surprising lack of contribution of VGCCs to synaptogenesis during early development in cultured hippocampal neurons.

Wang, Hong-Gang; Wang, Chuan; Pitt, Geoffrey S.

2011-01-01

278

Linear fibroblast alignment on sinusoidal wave micropatterns.  

PubMed

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

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

2012-12-20

279

Novel frequency-domain-based technique to detect stator interturn faults in induction machines using stator-induced voltages after switch-off  

Microsoft Academic Search

Traditionally, for medium- and high-voltage motors and generators, condition-based monitoring of stator faults is performed by measuring partial discharge activities. For low-voltage machines, negative-sequence impedance or currents are measured for the same. Such diagnostic schemes should be carefully implemented as supply voltage unbalance, manufacturing-related asymmetry, etc., also produce negative-sequence voltages. A few approaches based on motor current signature analysis have

Subhasis Nandi; Hamid A. Toliyat

2002-01-01

280

The voltage—current relationship and equivalent circuit implementation of parallel flux-controlled memristive circuits  

NASA Astrophysics Data System (ADS)

A flux-controlled memristor characterized by smooth cubic nonlinearity is taken as an example, upon which the voltage—current relationships (VCRs) between two parallel memristive circuits — a parallel memristor and capacitor circuit (the parallel MC circuit), and a parallel memristor and inductor circuit (the parallel ML circuit) — are investigated. The results indicate that the VCR between these two parallel memristive circuits is closely related to the circuit parameters, and the frequency and amplitude of the sinusoidal voltage stimulus. An equivalent circuit model of the memristor is built, upon which the circuit simulations and experimental measurements of both the parallel MC circuit and the parallel ML circuit are performed, and the results verify the theoretical analysis results.

Bao, Bo-Cheng; Feng, Fei; Dong, Wei; Pan, Sai-Hu

2013-06-01

281

Semiconductor quantized voltage source.  

PubMed

We realize and investigate an all-semiconductor quantized voltage source which generates quantized output voltages V(out) = f(h/e) linked only to two fundamental constants, the electron's charge e and Planck's constant h, and to an applied excitation frequency f. The device is based on an integrated quantized circuit of a single-electron pump operated at pumping frequency f and a quantum Hall device monolithically integrated in series. Robust output voltages up to several ?V are generated, which are expected to be scalable by orders of magnitude using present technology. The device might open a new route towards the closure of the quantum metrology triangle. PMID:23006195

Hohls, F; Welker, A C; Leicht, Ch; Fricke, L; Kaestner, B; Mirovsky, P; Müller, A; Pierz, K; Siegner, U; Schumacher, H W

2012-07-31

282

[One hundred years of sinusoidal cells in the liver].  

PubMed

Kupffer (1898) reported that the stellate cells were phagocytic endothelial cells, retracting his earlier view that these cells were perivascular cells. His new concept stimulated studies on the vital staining and the RES theory, while it ensued several controversies in liver histology. The original stellate cells were rediscovered in 1971, and were proved to be identical with several perisinusoidal cells reported previously. For this cell the term hepatic stellate cell has recently been adopted as the standardized name. The space of Disse is newly defined as the space between the endothelial cell-stellate cell complex and the parenchymal cells. The stellate cells display vitamin A-storage, collagen synthesis and may contract to regulate the sinusoidal blood flow and the fluid-exchange between the sinusoidal lumen and the space of Disse. The sinusoidal endothelial cells uptake injected lithium carmine and macromolecules by coated vesicles. Kupffer cells clear endotoxin, bacteria and apoptotic neutrophils and release various cytokines. The pit cells are the liver-associated NK cells and are activated by the administration of biological response modifiers, preventing tumor metastasis. Extrathymic pathways of T cell differentiation exist in the hepatic sinusoid. The dendritic cells differentiate in the sinusoid and translocate to the Glisson's sheath. Intralobular heterogeneity of sinusoidal cells have been observed. The sinusoidal cells communicate each other with autocrine and paracrine mechanisms to regulate various functions of the liver. PMID:9396207

Wake, K

1997-10-01

283

[Pathology along the liver sinusoids: endothelial and perisinusoidal findings].  

PubMed

Sinusoidal alterations unrelated to primary hepatocellular damage present without characteristic clinical findings and in these cases the liver biopsy is particularly important. Capillarization of sinusoids is characterized by closing of fenestration, formation of a basal membrane and by the expression of CD34 and is typical for active cirrhosis. In nodular regeneratory hyperplasia, capillarization indicates a local or general disturbance of perfusion. In large regenerative nodules, focal nodular hyperplasia and liver cell adenoma CD34-positive capillaries reflect afferent parts and CD34-negative sinusoids the efferent parts of the parenchymal vascular bed. HCC generally have a completely capillarized CD34-positive vascular bed. Hepatic angiosarcomas and epithelioid hemangioendotheliomas can be easily overseen in liver biopsies, if they spread along the sinusoids without detoriation of the acinar architecture and without significant alteration of the surrounding liver cell plates. Toxic damage of endothelial cells, post-sinusoidal stasis and sinusoidal hyperperfusion are the underlying pathogenetic principles of sinusoidal injury. Rupture and loss of the perisinusoidal reticulin fibres lead to peliosis hepatis. In these cases liver biopsy might disclose occlusion of the terminal liver veins (VOD). Perisinusoidal fibrosis can be caused by intrasinusoidal accumulation of pathologic cells, advanced intrasinusoidal macrophagocytic storage diseases and by activation of the vitamin A-storing hepatic stellate cells. Perisinusoidal amyloidosis can be the first sign of an underlying B-cell neoplasia. PMID:18210108

Fischer, H-P; Flucke, U; Zhou, H

2008-02-01

284

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

PubMed Central

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.

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

2010-01-01

285

Fluid Modeling of a Nitrogen Atmospheric-Pressure Planar Dielectric Barrier Discharge Driven by a Realistic Distorted Sinusoidal Alternating Current Power Source  

NASA Astrophysics Data System (ADS)

One-dimensional self-consistent simulations of a parallel-plate atmospheric-pressure nitrogen dielectric barrier discharge (DBD) are presented. The DBD was driven by a realistic distorted-sinusoidal voltage power source with a frequency of 60 kHz. The simulated discharge currents are in quantitative agreement with experimental measurements. N4+ ions gain more of the input electric power than electrons, which is unlike most glow discharges. The densities of all charged and neutral species increase exponentially with increasing applied peak voltage in the range of 6.2--8.6 kV. The higher the permittivity of the dielectric material, the larger the discharge current and the longer the period of gas breakdown. In addition, the quantity of accumulated charges at each electrode increases with increasing permittivity of the dielectric material. Finally, the increase in dielectric thickness from 1.0 to 2.0 mm greatly reduces the densities of all species and also the plasma absorbed by the power.

Cheng, Kai-Wen; Hung, Chieh-Tsan; Lin, Kun-Mo; Chiu, Yuan-Ming; Wu, Jong-Shinn; Yu, Jen-Perng

2012-11-01

286

Low voltage circuit design techniques for voltage controlled oscillator  

Microsoft Academic Search

This paper discusses some high frequency circuit design techniques for low voltage operation and low power consumption voltage controlled oscillators. The target operating voltage is 2 V (power supplied by only two pieces of rechargeable NiCd battery). Various resonators and circuit configurations were studied for optimal performance. A major difficulty was found in achieving high spectral purity on such low

Chung Ming Yuen; Kim Fung Tsang

1997-01-01

287

Contrasting characteristics of pulsed and sinusoidal cold atmospheric plasma jets  

SciTech Connect

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.

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

288

Contrasting characteristics of pulsed and sinusoidal cold atmospheric plasma jets  

NASA Astrophysics Data System (ADS)

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.

Walsh, J. L.; Shi, J. J.; Kong, M. G.

2006-04-01

289

A polarimetric glucose sensor using a liquid-crystal polarization modulator driven by a sinusoidal signal  

NASA Astrophysics Data System (ADS)

Rather than using a conventional Faraday modulator, this study adopts a liquid-crystal based rotator to modulate the azimuth of the linear polarized light in a sinusoidal signal for the measurement of glucose concentrations. The tilt angle of the LC director would vary as a sinusoidal-like function; however the modulating frequency in the sensing system is the double of the driving signal. A new signal demodulation algorithm, therefore, is developed that enables the polarization rotation angle corresponding to the glucose concentration to be derived. The standard deviation in rotation angle level of 0.00551° has been obtained, with a 0.998773 correlation coefficient between the reference and the measured values. The proposed measurement method has a minimum resolvable concentration of 0.2 g/dl. Compared to its conventional counterparts, the developed polarimeter potentially has a simpler structure, fewer optical elements, and a cheaper modulator component.

Lo, Yu-Lung; Yu, Tsung-Chih

2006-03-01

290

An intercomparison of AC voltage using a digitally synthesized source  

Microsoft Academic Search

An AC voltage intercomparison was conducted to determine the consistency of AC voltage measurements made at various standards laboratories. The transport standard used for this purpose was a NIST-developed digitally synthesized sinusoidal voltage source whose RMS (root-mean-square) value was calculated by measuring the DC level of each of the steps used to synthesize the sine wave. The uncertainty of the

N. M. Oldham; W. F. Bruce; C. M. Fu; A. G. Smith

1989-01-01

291

Nuclear deviation in hepatic parenchymal cells on sinusoidal surfaces in Arctic animals.  

PubMed

In normal rat and human, most of the nuclei of hepatic parenchymal cells are centrally located in the cytoplasm. However, it is reported that the nuclei of hepatic parenchymal cells are situated at a deviated position on sinusoidal surfaces under pathological situations such as chronic hepatitis, hepatocellular carcinoma, adenomatous hyperplasia, or regeneration. During a study on the mechanism of extreme vitamin A-accumulation in hepatic stellate cells of arctic animals including polar bears, arctic foxes, bearded seals, and glaucous gulls, we noticed that these arctic animals displayed the nuclear deviation in hepatic parenchymal cells on sinusoidal surfaces. In this study, we assessed the frequency of hepatic parenchymal cells showing the nuclear deviation on the sinusoidal surfaces in arctic animals. A significantly higher frequency of the nuclear deviation in hepatic parenchymal cells was seen in polar bears (89.8+/-3.4%), arctic foxes (68.6+/-10.5%), bearded seals (63.6+/-8.4%), and glaucous gulls (24.2+/-5.8%), as compared to that of control rat liver (9.8+/-3.5%). However, no pathological abnormality such as fibrosis or necrosis was observed in hepatic parenchymal and nonparenchymal cells of arctic animals, and there were no differences in the intralobular distribution of parenchymal cells displaying the nuclear deviation in the livers from either arctic animals and control rats. The hepatic sinusoidal littoral cells such as stellate cells or extracellular matrix components in the perisinusoidal spaces may influence the nuclear positioning and hence the polarity and intrinsic physiological function of parenchymal cells. PMID:11482455

Sato, M; Miura, M; Kojima, N; Higashi, N; Imai, K; Sato, T; Wold, H L; Moskaug, J O; Blomhoff, R; Wake, K; Roos, N; Berg, T; Norum, K R; Senoo, H

2001-04-01

292

Respiratory variability in RR interval during sinusoidal exercise  

Microsoft Academic Search

The R-R interval varies with the cycles of respiration. The response of the variability in the R-R interval with respiration\\u000a was examined during sinusoidal cycle exercise in 12 healthy young male subjects. Work rate varied sinusoidally between 30\\u000a W and 60% maximal oxygen uptake for an 8-min period. The higher the heart rate (HR), the smaller was the magnitude of

Ryoko Sone; Fumio Yamazaki; Nobuharu Fujii; Yoshiyuki Fukuoka; Haruo Ikegami

1996-01-01

293

High frequency pressure oscillator for microcryocoolers  

NASA Astrophysics Data System (ADS)

Microminiature pulse tube cryocoolers should operate at a frequency of an order higher than the conventional macro ones because the pulse tube cryocooler operating frequency scales inversely with the square of the pulse tube diameter. In this paper, the design and experiments of a high frequency pressure oscillator is presented with the aim to power a micropulse tube cryocooler operating between 300 and 80 K, delivering a cooling power of 10 mW. Piezoelectric actuators operate efficiently at high frequencies and have high power density making them good candidates as drivers for high frequency pressure oscillator. The pressure oscillator described in this work consists of a membrane driven by a piezoelectric actuator. A pressure ratio of about 1.11 was achieved with a filling pressure of 2.5 MPa and compression volume of about 22.6 mm3 when operating the actuator with a peak-to-peak sinusoidal voltage of 100 V at a frequency of 1 kHz. The electrical power input was 2.73 W. The high pressure ratio and low electrical input power at high frequencies would herald development of microminiature cryocoolers.

Vanapalli, S.; Ter Brake, H. J. M.; Jansen, H. V.; Zhao, Y.; Holland, H. J.; Burger, J. F.; Elwenspoek, M. C.

2008-04-01

294

The relative evimunity of the skin and cardiovascular system to the direct effects of high voltage - high frequency component electrical pulses  

Microsoft Academic Search

This paper summarizes our testing to date of commercdy available battery powered hand held electric pulse generators, sometimes called TASER's, stun guns, or Less Than Lethal Weapons (LTLW). We present the generalized electronic properties of these devices along with physiologic effects on human and animal subjects. providing a differential voltage divider factor of 1ooO. Further voltage division was accomplished using

Robert A. Stratbucker; Matthew G. Marsh

1993-01-01

295

System analysis of Phycomyces light-growth response with sum-of-sinusoids test stimuli.  

PubMed Central

The light-growth response of Phycomyces has been studied with the sum-of-sinusoids method of nonlinear system identification (Victor, J.D., and R.M. Shapley, 1980, Biophys. J., 29:459). This transient response of the sporangiophore has been treated as a black-box system with one input (logarithm of the light intensity, I) and one output (elongation rate). The light intensity was modulated so that log I, as a function of time, was a sum of sinusoids. The log-mean intensity was 10(-4) W m-2 and the wavelength was 477 nm. The first- and second-order frequency kernels, which represent the linear and nonlinear behavior of the system, were obtained from the Fourier transform of the response at the appropriate component and combination frequencies. Although the first-order kernel accounts for most of the response, there remains a significant nonlinearity beyond the logarithmic transducer presumed to occur at the input of the sensory transduction chain. From the analysis of the frequency kernels, we have derived a dynamic nonlinear model of the light-growth response system. The model consists of a nonlinear subsystem followed by a linear subsystem. The model parameters were estimated from a combined nonlinear least-squares fit to the first- and second-order frequency kernels.

Pratap, P; Palit, A; Lipson, E D

1986-01-01

296

A Josephson Voltage Calibrator  

Microsoft Academic Search

An automatic voltage calibrator for voltages ranging from ?1 V to +1 V is described. The device is based on a Josephson array with Nb-AlOx-Al-AlOx-Nb junctions. Being illuminated by microwave radiation with a frequency of 65.2 GHz, the array, in which the operating supply currents of three junction sections are set by a multichannel digital source controlled by a personal

I. Ya. Krasnopolin; V. L. Ugolev

2005-01-01

297

Millimeter-Wave Antenna of a Travelling-Wave Long Sinusoidal Slot in the Narrow Face of a Rectangular Waveguide  

NASA Astrophysics Data System (ADS)

A travelling-wave long sinusoidal slot in the narrow face of a millimeter-wave (Ka-Band) rectangular waveguide is investigated. To the best of our knowledge, a slot of this shape is applied to the narrow face of a rectangular waveguide for the first time at this frequency range. The analytical study is based on the magnetic current model. Experimentally, far-field and S-parameters are measured and a good match is obtained between analytical and measured patterns. Frequency scan rates and velocity ratios of the structure are calculated. The effect of the sinusoidal slot's geometrical parameters (amplitude, period and number of periods) on the radiation patterns is also investigated. The drawback of the sinusoidal radiator is its cross-polarized beam that is not convenient for antenna applications. These co and cross-polarized beams scan in two different angle regions. To filter/suppress the cross-polarized beam, a grid polarizer is mounted to the sinusoidal slot and a 15 dB suppression level is reached. S-parameters measurement shows that the antenna efficiency increases remarkably after the application of the grid polarizer to the slot.

Salman, A. Oral

2010-12-01

298

Voltage-programmable liquid optical interface  

NASA Astrophysics Data System (ADS)

Recently, there has been intense interest in photonic devices based on microfluidics, including displays and refractive tunable microlenses and optical beamsteerers that work using the principle of electrowetting. Here, we report a novel approach to optical devices in which static wrinkles are produced at the surface of a thin film of oil as a result of dielectrophoretic forces. We have demonstrated this voltage-programmable surface wrinkling effect in periodic devices with pitch lengths of between 20 and 240 µm and with response times of less than 40 µs. By a careful choice of oils, it is possible to optimize either for high-amplitude sinusoidal wrinkles at micrometre-scale pitches or more complex non-sinusoidal profiles with higher Fourier components at longer pitches. This opens up the possibility of developing rapidly responsive voltage-programmable, polarization-insensitive transmission and reflection diffraction devices and arbitrary surface profile optical devices.

Brown, C. V.; Wells, G. G.; Newton, M. I.; McHale, G.

2009-07-01

299

Frequency selectivity of synaptic exocytosis in frog saccular hair cells  

PubMed Central

The ability to respond selectively to particular frequency components of sensory inputs is fundamental to signal processing in the ear. The frog (Rana pipiens) sacculus, which is used for social communication and escape behaviors, is an exquisitely sensitive detector of sounds and ground-borne vibrations in the 5- to 200-Hz range, with most afferent axons having best frequencies between 40 and 60 Hz. We monitored the synaptic output of saccular sensory receptors (hair cells) by measuring the increase in membrane capacitance (?Cm) that occurs when synaptic vesicles fuse with the plasmalemma. Strong stepwise depolarization evoked an exocytic burst that lasted 10 ms and corresponded to the predicted capacitance of all docked vesicles at synapses, followed by a 20-ms delay before additional vesicle fusion. Experiments using weak stimuli, within the normal physiological range for these cells, revealed a sensitivity to the temporal pattern of membrane potential changes. Interrupting a weak depolarization with a properly timed hyperpolarization increased ?Cm. Small sinusoidal voltage oscillations (±5 mV centered at ?60 mV) evoked a ?Cm that corresponded to 95 vesicles per s at each synapse at 50 Hz but only 26 vesicles per s at 5 Hz and 27 vesicles per s at 200 Hz (perforated patch recordings). This frequency selectivity was absent for larger sinusoidal oscillations (±10 mV centered at ?55 mV) and was largest for hair cells with the smallest sinusoidal-stimuli-evoked Ca2+ currents. We conclude that frog saccular hair cells possess an intrinsic synaptic frequency selectivity that is saturated by strong stimuli.

Rutherford, Mark A.; Roberts, William M.

2006-01-01

300

Time-of-flight radio-frequency mass separator for continuous low-energy ion beams  

NASA Astrophysics Data System (ADS)

A novel concept for a time-of-flight radio-frequency mass separator for low-energy beams is investigated. The concept is based on two sets of deflectors with sinusoidally-varying applied voltage and at least one Einzel lens. Results of analytical calculation and numerical simulation are presented and compared. Potential advantages of such a scheme include a resolving power similar to that of simple electromagnetic separators while at lower costs, as well as the possibility to incorporate the scheme relatively easily into existing electrostatic beam transport systems.

Keller, Andrew J.; Bollen, Georg

2008-02-01

301

SLM-based sinusoidal fringe projection under coherent illumination  

NASA Astrophysics Data System (ADS)

The paper is dedicated to SLM implementation of a sinusoidal phase grating for fringe projection profilometry with sinusoidal fringes. A low-contrast sinusoidal phase grating is capable of projecting focused sinusoidal fringes with satisfactory visibility in a large spatial region under coherent divergent illumination. The paper presents analysis of distortions in the projected fringes due to phase quantization when the phase grating is generated by a phase-only 8-bit SLM. We showed by simulation of propagation in the free space that the spread of intensity fluctuations of the projected fringes comprises 4–5 gray levels if an SLM with a 2? phase span is used and is much lower for an SLM with ?/2 phase span. In addition, we proved that distortion due to the phase encoding of the grating complex amplitude can be modeled as gamma distortion with an invariable behavior in time at small values of the modulation parameter and removed by a proper correction of fringes after polyspectral analysis. The experiments we made with an 8-bit SLM of ?/2 phase span confirmed the ability of this optical element to project sinusoidal fringes with a high spectral purity.

Berberova, Natalia; Stoykova, Elena; Kang, Hoonjong; Park, Joo Sup; Ivanov, Branimir

2013-09-01

302

Phase and amplitude retrieval of objects embedded in a sinusoidal background from its diffraction pattern  

SciTech Connect

Efforts of phase and amplitude retrieval from diffraction patterns have almost exclusively been applied for nonperiodic objects. We investigated the quality of retrieval of nonperiodic objects embedded in a sinusoidal background, using the approach of iterative hybrid input-output with oversampling. Two strategies were employed; one by filtering in the frequency domain prior to phase retrieval, and the other by filtering the phase or amplitude image after retrieval. Results obtained indicate better outcomes with the latter approach provided detector noise is not excessive.

Wu, Chu; Ng, Tuck Wah; Neild, Adrian

2010-04-01

303

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.

304

Measurement of diffusion parameters using a sinusoidal iontophoretic source in rat cortex.  

PubMed

A new method was developed to extract diffusion parameters in brain tissue using a sinusoidal iontophoretic point source of tetramethylammonium operated at different frequencies. The resulting steady state oscillating extracellular concentration of this probe molecule was continuously monitored using an ion-selective microelectrode located about 100 microm from the source. Because the probe molecules must diffuse through the extracellular space (ECS), the oscillating concentration at the recording location will develop a phase lag and an amplitude attenuation relative to the sinusoidal source. These two components of the signal can be analyzed to determine the tortuosity factor lambda and the ECS volume fraction alpha. The method also measures the nonspecific clearance rate constant kappa. In brain slices this reflects washout of diffusing molecules. Values of alpha (0.18+/-0.05) and lambda (1.67+/-0.08) obtained from this frequency method in rat cortical slices were similar to those obtained by the real-time iontophoretic method employing a square pulse source. The relative merits of the frequency method compared to the pulse method are discussed. PMID:12535769

Chen, Kevin C; Nicholson, Charles

2002-12-31

305

Full-spectrum nonlinear response of a sinusoidally modulated rotating disk electrode  

NASA Astrophysics Data System (ADS)

The nonlinear behavior of a sinusoidally modulated rotating disk electrode (RDE) is analyzed to identify the flow and concentration field interactions that lead to resonance and nullification conditions in the electrochemical response of the system. Steady periodic solutions to the von Kármán self-similar form of the Navier-Stokes equations and convective diffusion equation are examined using a combined Fourier transform/perturbation approach that yields a set of frequency dispersion equations solved using the finite element method. Experimental measurements using a RDE with sinusoidal angular velocity waveform ?=?0+?? cos(?0t) are compared to theory for modulation amplitudes ??/?0<1 and electrolyte Schmidt number of 1680. The modulation frequency ?0 is varied from the quasisteady to high-frequency limits to obtain the phase and amplitude of the mean, fundamental, and higher-harmonic limiting current. We show that distinct features (resonances and nullifications) in the nonlinear mean and higher harmonic components of limiting current result from constructive and destructive (in phase and 180° out of phase, respectively) interactions between cross terms of the oscillating components in the axial flow and concentration fields near the disk surface.

Wilson, Jamie R.; Adler, Stuart B.; Schwartz, Daniel T.

2005-06-01

306

Discretization of quasi-sinusoidal diffraction gratings printed on acetates  

NASA Astrophysics Data System (ADS)

The aim of this work is to propose the use of printed acetate sheets as quasi-sinusoidal 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 printers. A study of the discretization effects 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 semi-sinusoidal 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 roughness average of the impressions as to observe the behavior of the ink on the acetate.

Mora-González, Miguel; Pérez Ladrón de Guevara, Héctor; Muńoz-Maciel, Jesús; Chiu-Zarate, Roger; Casillas, Francisco J.; Gómez-Rosas, Gilberto; Peńa-Lecona, Francisco G.; Vázquez-Flores, Zuleima Montserrat

2009-09-01

307

Frequency analysis of DC tolerant current transformers  

NASA Astrophysics Data System (ADS)

This article deals with wide frequency range behaviour of DC tolerant current transformers that are usually used in modern static energy meters. In this application current transformers must comply with European and International Standards in their accuracy and DC tolerance. Therefore, the linear DC tolerant current transformers and double core current transformers are used in this field. More details about the problems of these particular types of transformers can be found in our previous works. Although these transformers are designed mainly for power distribution network frequency (50/60 Hz), it can be interesting to understand their behaviour in wider frequency range. Based on this knowledge the new generations of energy meters with measuring quality of electric energy will be produced. This solution brings better measurement of consumption of nonlinear loads or measurement of non-sinusoidal voltage and current sources such as solar cells or fuel cells. The determination of actual power consumption in such energy meters is done using particular harmonics component of current and voltage. We measured the phase and ratio errors that are the most important parameters of current transformers, to characterize several samples of current transformers of both types.

Mlejnek, P.; Kaspar, P.

2013-09-01

308

Sinusoidal galvanic vestibular stimulation (sGVS) induces a vasovagal response in the rat  

PubMed Central

Blood pressure (BP) and heart rate (HR) were studied in isoflurane-anesthetized Long-Evans rats during sinusoidal galvanic vestibular stimulation (sGVS) and sinusoidal oscillation in pitch to characterize vestibular influences on autonomic control of BP and HR. sGVS was delivered binaurally via Ag/AgCl needle electrodes inserted over the mastoids at stimulus frequencies 0.008–0.4 Hz. Two processes affecting BP and HR were induced by sGVS: 1) a transient drop in BP (?15–20 mmHg) and HR (?3 beat*s?1), followed by a slow recovery over 1–6 min; and 2) inhibitory modulations in BP (?4.5 mmHg/g) and HR (?0.15 beats*s?1/g) twice in each stimulus cycle. The BP and HR modulations were approximately in-phase with each other and were best evoked by low stimulus frequencies. A wavelet analysis indicated significant energies in BP and HR at scales related to twice and four times the stimulus frequency bands. BP and HR were also modulated by oscillation in pitch at frequencies 0.025–0.5 Hz. Sensitivities at 0.025 Hz were ?4.5 mmHg/g (BP) and ?0.17 beat*s?1/g (HR) for pitches of 20–90°. The tilt-induced BP and HR modulations were out-of-phase, but the frequencies at which responses were elicited by tilt and sGVS were the same. The results show that the sGVS-induced responses, which likely originate in the otolith organs, can exert a powerful inhibitory effect on both BP and HR at low frequencies. These responses have a striking resemblance to human vasovagal responses. Thus, sGVS-activated rats can potentially serve as a useful experimental model of the vasovagal response in humans.

Martinelli, Giorgio P.; Ogorodnikov, Dmitri; Xiang, Yongqing; Raphan, Theodore; Holstein, Gay R.; Yakushin, Sergei B.

2011-01-01

309

Generation of sinusoidal fringes with a holographic phase grating and a phase-only spatial light modulator  

NASA Astrophysics Data System (ADS)

A variety of pattern projection methods for the three-dimensional capture of objects is based on the generation of purely sinusoidal fringes. This is not an easy task, especially when a portable non-interferometric system for outdoor usage is required. The use of phase gratings with coherent illumination as a possible solution has the advantage of providing good stability and a large measurement volume. In this work, we analyze the quality of fringes projected with two sinusoidal phase gratings. The first grating is recorded on a silver-halide holographic plate by means of a Michelson interferometer. The spatial resolution of the silver-halide material used is greater than 6000 lines per millimeter, and the recorded grating is practically analogous to a smooth variation of the phase profile. The second grating is formed as a sinusoidal phase variation on a liquid crystal-on-silicon phase-only reflective display with a resolution of 1920×1080 pixels, a pixel pitch of 8??m and 256 phase levels. The frequency content of the fringes projected with both gratings is analyzed and compared on the basis of the calculated Fresnel diffraction pattern, taking into account that the sinusoidal phase distribution in the case of a spatial light modulator is both sampled and quantized. Experimental fringe patterns projected using both gratings are also provided.

Berberova, Natalia; Stoykova, Elena; Sainov, Ventseslav

2012-05-01

310

Capacitor Voltage Balancing Schemes in Flying Capacitor Multilevel Inverters  

Microsoft Academic Search

This paper focuses on the development of capacitor voltage balancing methods in a flying capacitor multilevel inverter (FCMLI). Three such strategies have been described and have been applied to a five-level CMLI. The sinusoidal pulse width modulation technique has been used while making the proposals. The first scheme works on the principle of selection of the most favorable switching state

Anshuman Shukla; A. Ghosh; A. Joshi

2007-01-01

311

Single-Switch Single-Phase Voltage-Quadrupler Rectifier  

NASA Astrophysics Data System (ADS)

A single-phase voltage-quadrupler rectifier using a single active power device is presented. This is based on the combination of a half-bridge rectifier and the circuits operated in the switching states for pumping action to pump twice the peak supply voltage onto each of the output capacitors. The experimental prototype employing an insulated-gate bipolar transistor and a controller for output voltage regulation is implemented to investigate the operation. The experimental results confirm that the input current can almost be waveshaped sinusoidally with a near-unity power factor under the output voltage quadruplication.

Itoh, Ryozo; Ishizaka, Kouichi; Neba, Yasuhiko; Hirata, Yuki

312

Vestibular and pulse-related modulation of skin sympathetic nerve activity during sinusoidal galvanic vestibular stimulation in human subjects  

Microsoft Academic Search

We have previously shown that sinusoidal galvanic vestibular stimulation (sGVS), a means of a selectively modulating vestibular\\u000a afferent input without affecting other inputs, can cause partial entrainment of muscle sympathetic nerve activity (MSNA).\\u000a Given that motion sickness causes sweating and pallor, we tested the hypothesis that sGVS also entrains skin sympathetic nerve\\u000a activity (SSNA), but that the optimal frequencies are

Cheree James; Alexandra Stathis; Vaughan G. Macefield

2010-01-01

313

Behavior of soft piezoelectric ceramics under high sinusoidal electric fields  

NASA Astrophysics Data System (ADS)

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.

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

1998-09-01

314

Using Antenna Arrays to Motivate the Study of Sinusoids  

ERIC Educational Resources Information Center

Educational activities involving antenna arrays to motivate the study of sinusoids are described. Specifically, using fundamental concepts related to phase and simple geometric arguments, students are asked to predict the location of interference nulls in the radiation pattern of two-element phased array antennas. The location of the radiation…

Becker, J. P.

2010-01-01

315

Sinusoidal phase grating created by a tunably buckled surface  

Microsoft Academic Search

We investigate a buckling instability by both small angle light scattering and atomic force microscopy, demonstrating that a tunable phase grating can be created with a mechanical instability. The instability is realized in a prestressed silicone sheet coated with a glassy polymer film. Compression of the sample results in a sinusoidally wrinkled surface where the amplitude is controlled by the

Christopher Harrison; Christopher M. Stafford; Wenhua Zhang; Alamgir Karim

2004-01-01

316

Optical propagation through horizontally stratified, quasi-sinusoidal, phase gratings  

Microsoft Academic Search

A general theory was developed for determining the reflection and transmission coefficients of holographically produced, horizontally stratified, quasi-sinusoidal, phase gratings as a function of incident angle, wavelength and polarization. Theorems are stated and proved about polarization effects and about the relationship between the spectral and angular characteristics of such gratings. Strong similarities are shown to exist between these gratings and

K. A. Winick

1981-01-01

317

Using Antenna Arrays to Motivate the Study of Sinusoids  

ERIC Educational Resources Information Center

|Educational activities involving antenna arrays to motivate the study of sinusoids are described. Specifically, using fundamental concepts related to phase and simple geometric arguments, students are asked to predict the location of interference nulls in the radiation pattern of two-element phased array antennas. The location of the radiation…

Becker, J. P.

2010-01-01

318

Sinusoidal variables from the Tycho Epoch Photometry Annex  

Microsoft Academic Search

The Tycho Epoch Photometry Annex A, a data base of photometry of more than 34 000 bright stars, has been searched for periodic variable stars with approximately sinusoidal light curves. Advantage was taken of special properties of the observing programme (photometry in two wavebands, availability of repeated measurements) to use simple but efficient variable selection criteria. Details of 70 strong

Chris Koen; Robert Schumann

1999-01-01

319

Single-Phase Voltage-Quadrupler Rectifier Reducing Input Current Distortion  

NASA Astrophysics Data System (ADS)

A single-phase voltage-quadrupler rectifier with reduced input current distortion is presented. This can be operated in the switching states for pumping action to pump twice the peak supply voltage onto each of the output capacitors and for forcing the input current to follow its sinusoidal reference in the vicinity of a zero crossing of the supply. The experimental prototype, using two dual-switch power modules with IGBTs and a controller for output voltage regulation, is implemented to investigate the operation. The experimental results confirm that the input current can be waveshaped sinusoidally with a near-unity power factor.

Itoh, Ryozo; Ishizaka, Kouichi; Neba, Yasuhiko; Hirata, Yuki

320

Voltage Controlled Voltage Source (VCVS)  

NSDL National Science Digital Library

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.

Dorf, Richard C.; Svoboda, James A.

2008-11-27

321

Channel estimation using time-frequency techniques  

Microsoft Academic Search

We propose the use of time-varying signals and time-frequency techniques to estimate fast fading channels with unknown state information. Specifically, we apply the reassigned spectrogram to estimate multiple sinusoids resulting from transmitting and processing two linear frequency-modulated (FM) chirp pilots. The estimation procedure is complicated by the need to pair sinusoids resulting from the same multipath. This problem is overcome

Hao Shen; Antonia Papandreou-Suppappola

2005-01-01

322

Inhibition of electromyographic activity in human triceps surae muscles during sinusoidal rotation of the foot.  

PubMed Central

Torque and electromyographic (EMG) responses to sinusoidal rotations of the foot were measured. The frequency range of the movements was 0.5 Hz to 15 Hz at amplitudes ranging between 1 and 10 degrees. At frequencies above 7 Hz, the EMG activity did not follow individual foot rotation cycles. The EMG activity was inhibited whenever the peak torque was large with respect to the first cycle peak torque. Dantrolene sodium reduced the torque developed in triceps surae, allowing the EMG activity to follow individual stretch cycles. As the drug was metabolized, the EMG activity returned to the character seen in the pre-drug control--that is, inhibition on alternate stretch cycles. It is concluded that the EMG inhibition phenomenon can be attributed in part to force receptors in muscle but that these receptors are not the sole contributors to the inhibition.

Freedman, W; Herman, R

1975-01-01

323

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

NASA Astrophysics Data System (ADS)

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.

Reenbohn, W. L.; Mahato, Mangal C.

2013-09-01

324

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

PubMed

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

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

2013-03-22

325

Improved sinusoidal phase plate to extend depth of field in incoherent hybrid imaging systems.  

PubMed

An improved sinusoidal phase plate is proposed by adding a new parameter to the conventional sinusoidal phase plate. A series of performance comparisons are made among various phase plates, including sinusoidal, cubic phase, and the modified logarithmic phase. The results demonstrate that the improved sinusoidal phase plate can further extend the depth of field in incoherent hybrid imaging systems, with lower surface relief phase structures fabricated in photoresist (AR-N 4340, ALL Resist, Germany). PMID:23114354

Wang, Jingang; Bu, Jing; Wang, Mingwei; Yang, Yong; Yuan, X-C

2012-11-01

326

A description for computed tomography based on sinusoidal curves.  

PubMed

A new description for computed tomography, parallel and equal to Radon transformation but based on sinusoidal functions rather than line integrals, is introduced. This representation contributes an effective algorithm to reduce metal artefacts in reconstruction. Using this method, the information included in the scan data corresponding to the metal implants can be separated from the original projection, an amending method rather than interpolation is therefore provided to reach higher accuracy for reconstruction. The method is with low complexity in computation, and can be combined online with filtered backprojection (FBP), which is the most widely used algorithm in practice, to improve the quality of the reconstructed image. Also, the method has the potential to deal with the artefacts caused by beam hardening and partial volume, and to be developed into a straight reconstruction algorithm based on the sinusoidal representation. Examples are presented for clearer description and demonstration. PMID:22388291

Liu, J J; Watt-Smith, S R; Smith, S M

2003-01-01

327

Investigation of Calibrating Force Transducer Using Sinusoidal Force  

SciTech Connect

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.

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

328

Pattern projection profilometry with sinusoidal gratings under coherent illumination  

NASA Astrophysics Data System (ADS)

The work considers the important issue of finding proper illumination geometry for pattern projection profilometric measurement with a sinusoidal grating under coherent divergent illumination. This is done by analysis of the Talbot carpets for gratings with phase or amplitude modulation at variable distance between the source and the grating at the assumption that the grating modulation depth ensures negligible contribution of the higher harmonics. The goal is to propose reliable procedure for choosing the most suitable elongation of the point source for a given grating and a given wavelength. The obtained dependences are verified by an experimental study of the quality of the projected fringes using a thin sinusoidal phase grating recorded on a silver-halide holographic plate. The result of the profilometric measurement with the recorded grating is also included. [Figure not available: see fulltext.

Stoykova, Elena; Berberova, Natalia; Park, Joo Sup; Kang, Hoonjong; Sainov, Ventseslav

2013-03-01

329

Structural and functional aspects of liver sinusoidal endothelial cell fenestrae: a review  

PubMed Central

This review provides a detailed overview of the current state of knowledge about the ultrastructure and dynamics of liver sinusoidal endothelial fenestrae. Various aspects of liver sinusoidal endothelial fenestrae regarding their structure, origin, species specificity, dynamics and formation will be explored. In addition, the role of liver sinusoidal endothelial fenestrae in relation to lipoprotein metabolism, fibrosis and cancer will be approached.

Braet, Filip; Wisse, Eddie

2002-01-01

330

Immunohistochemical patterns of human liver sinusoids under different conditions of pathologic perfusion  

Microsoft Academic Search

This study reports the effects of altered hepatic perfusion on the sinusoidal bed and the phenotypic characteristics of sinusoidal endothelial cells (SECs). Sinusoids were studied by the application of endothelial cell markers (CD31, CD34, CD105, and ATZ 11) in lesions with localized increased perfusion (liver cell adenoma, focal nodular hyperplasia, and macroregenerative nodule), in chronic congestion, in decreased portovenous inflow

Ingo Theuerkauf; Hui Zhou; Hans-Peter Fischer

2001-01-01

331

Sparse Sinusoidal Signal Representation for Speech and Music Signals  

Microsoft Academic Search

We present a sparse representation called Fixed Dimension Modified Sinusoid Model (FD-MSM) for parametric analysis of audible\\u000a signals including speech, music and mixtures. Compared with other analysis models, the proposed scheme is both pitch independent\\u000a and appropriate for sparse signal representation commonly found as a favorable choice for speech enhancement and sound separation.\\u000a Using the state-of-the-art Principle Component Analysis (PCA)

Pejman Mowlaee; Amirhossein Froghani; Abolghasem Sayadiyan

332

Transventricular defibrillation thresholds using quarter and half sinusoidal pulses  

Microsoft Academic Search

Transventricular peak current defibrillation thresholds using quarter (5 ms) and half (10 ms) sinusoidal pulses were determined\\u000a in dogs under conditions of normothermia. For 5 ms, the overall average was 59·6 mAg?1 of heart (s.d. 21·00) in a total of ten animals and 88 successful defibrillations. For 10 ms, the average over seven dogs\\u000a and 51 determinations was 52·5 mAg?1

J. E. Monzón; M. E. Valentinuzzi

1982-01-01

333

Oxaliplatin-related sinusoidal obstruction syndrome mimicking metastatic liver tumors.  

PubMed

A 40-year-old woman who had undergone a curative low anterior resection for advanced rectal cancer was admitted to our hospital. She had been administrated oxaliplatin-based chemotherapy as postoperative adjuvant chemotherapy. The contrast-enhanced computed tomography revealed three hypovascular tumors, 3.0, 1.5 and 1.0?cm in diameter, located in the right hepatic lobe. The hepatocyte phase of the gadoxetic acid-enhanced magnetic resonance imaging demonstrated these lesions as hypointense tumors relative to the surrounding hepatic parenchyma. All these findings of the preoperative imaging modalities were compatible to metastatic liver tumors from the rectal cancer, and right hepatic lobectomy was successfully performed. Histopathologically, the tumors revealed sinusoidal dilation and severe congestion outlined by atrophic hepatocyte trabeculae, which was known as peliosis hepatis. The perisinusoidal space of Disse was extensively dilated and contained many erythrocytes. Taking these findings into account, the hepatic tumors were considered to be the space-occupying lesions resulting from the sinusoidal obstruction syndrome. We herein report the first case of focal sinusoidal obstruction syndrome mimicking metastatic liver tumors. PMID:23730707

Arakawa, Yusuke; Shimada, Mitsuo; Utsunomya, Tohru; Imura, Satoru; Morine, Yuji; Ikemoto, Testuya; Hanaoka, Jun; Sugimoto, Koji; Bando, Yoshimi

2013-06-01

334

Retarding field analyzer for ion energy distribution measurements at a radio-frequency biased electrode  

SciTech Connect

A retarding field energy analyzer designed to measure ion energy distributions impacting a radio-frequency biased electrode in a plasma discharge is examined. The analyzer is compact so that the need for differential pumping is avoided. The analyzer is designed to sit on the electrode surface, in place of the substrate, and the signal cables are fed out through the reactor side port. This prevents the need for modifications to the rf electrode--as is normally the case for analyzers built into such electrodes. The capabilities of the analyzer are demonstrated through experiments with various electrode bias conditions in an inductively coupled plasma reactor. The electrode is initially grounded and the measured distributions are validated with the Langmuir probe measurements of the plasma potential. Ion energy distributions are then given for various rf bias voltage levels, discharge pressures, rf bias frequencies - 500 kHz to 30 MHz, and rf bias waveforms - sinusoidal, square, and dual frequency.

Gahan, D.; Hopkins, M. B. [National Centre for Plasma Science and Technology, Dublin City University, Glasnevin, Dublin 9 (Ireland); Dolinaj, B. [Impedans Ltd., Invent Centre, Dublin City University, Glasnevin, Dublin 9 (Ireland)

2008-03-15

335

Retarding field analyzer for ion energy distribution measurements at a radio-frequency biased electrode.  

PubMed

A retarding field energy analyzer designed to measure ion energy distributions impacting a radio-frequency biased electrode in a plasma discharge is examined. The analyzer is compact so that the need for differential pumping is avoided. The analyzer is designed to sit on the electrode surface, in place of the substrate, and the signal cables are fed out through the reactor side port. This prevents the need for modifications to the rf electrode--as is normally the case for analyzers built into such electrodes. The capabilities of the analyzer are demonstrated through experiments with various electrode bias conditions in an inductively coupled plasma reactor. The electrode is initially grounded and the measured distributions are validated with the Langmuir probe measurements of the plasma potential. Ion energy distributions are then given for various rf bias voltage levels, discharge pressures, rf bias frequencies--500 kHz to 30 MHz, and rf bias waveforms--sinusoidal, square, and dual frequency. PMID:18377005

Gahan, D; Dolinaj, B; Hopkins, M B

2008-03-01

336

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

SciTech Connect

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.

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

337

Instrument for Measuring True-RMS AC Voltage and AC Voltage Fluctuations.  

National Technical Information Service (NTIS)

This invention relates to devices for measuring fluctuations in alternating current voltage, and more particularly to instruments for measuring true-RMS line voltages, frequency and percent regulation in connection with measurements required in the testin...

J. L. Silbergerg

1980-01-01

338

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

Microsoft Academic Search

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

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

1999-01-01

339

Development of Multi-Functional Voltage Restore System  

NASA Astrophysics Data System (ADS)

Recently, with the dawn of the electric deregulation, the installation of distributed generation with power electronics device has grown. This current causes a greater concern of power quality, primarily voltage disturbance for power companies, and their interest in power quality is peaking. Utilities are also interested in keeping their customers satisfied, as well as keeping them on-line and creating more revenue for the utility. As a countermeasure against the above surroundings, a variety type of devices based on power electronics has been developed to protect customers' load from power line voltage disturbance. One of them is the series type voltage restore. The series device is an active device, designed to provide a pure sinusoidal load voltage at all times, correcting voltage disturbance. Series type device compensates for voltage anomalies by inserting the ‘missing’ voltage onto the line through insertion transformer and inverter. This paper shows the setting guideline of target level to compensate voltage disturbance, that is, voltage dip, voltage harmonics, voltage imbalance and voltage flicker, and the design approach of the prototype of series voltage restores to accomplish the required compensation level. The prototype system gives satisfactory compensation performance through evaluation tests, which confirm the validity and effectiveness of the system.

Suzuki, Satoshi; Ueda, Yoshinobu; Koganezawa, Takehisa; Ogihara, Yoshinori; Mori, Kenjiro; Fukazu, Naoaki

340

The influence of anatomical and physiological parameters on the interference voltage at the input of unipolar cardiac pacemakers in low frequency electric fields  

NASA Astrophysics Data System (ADS)

The problem of electromagnetic interference of electronic implants such as cardiac pacemakers has been well known for many years. An increasing number of field sources in everyday life and occupational environment leads unavoidably to an increased risk for patients with electronic implants. However, no obligatory national or international safety regulations exist for the protection of this patient group. The aim of this study is to find out the anatomical and physiological worst-case conditions for patients with an implanted pacemaker adjusted to unipolar sensing in external time-varying electric fields. The results of this study with 15 volunteers show that, in electric fields, variation of the interference voltage at the input of a cardiac pacemaker adds up to 200% only because of individual factors. These factors should be considered in human studies and in the setting of safety regulations.

Joosten, S.; Pammler, K.; Silny, J.

2009-02-01

341

Influence of Switching Frequency on Eddy-Current Losses in a Three-Phase, Three-Limb Transformer Core Subjected to PWM Voltage Excitation  

Microsoft Academic Search

Transformers are key elements in power generation, transmission and distribution systems. Transformers under PWM supply are essential elements in industrial applications such as active power line conditioning, electrified railway power systems, PWM DC-DC power converters. Assessing the performance of transformers under PWM supplies is relevant to these applications. In this paper, the variation of iron losses with switching frequency in

Xiao Guang Yao; Anthony J. Moses; Juan Sagarduy; Fatih J. Anayi

2007-01-01

342

A SiC JFET Driver for a 5 kW, 150 kHz Three-Phase Sinusoidal-Input, Sinusoidal-Output PWM Converter  

Microsoft Academic Search

Silicon carbide (SiC) power semiconductor devices are capable of being operated at higher voltages, frequencies and temperatures than silicon power devices. These SiC device capabilities will provide the power electronics designer with new possibilities to produce compact designs. Presently the JFET is the only controlled turn off\\/on SiC device that is close to commercialization and available as restricted samples. However

S. Round; M. Heldwein; J. Kolar; I. Hofsajer; Rand Afrikaans; P. Friedrichs

343

The Evaluation of Discomfort Produced by Multiple Frequency Whole-Body Vibration  

Microsoft Academic Search

The discomfort produced by multiple frequency whole-body vertical vibration has been studied in three expriments. Subjects were required to adjust the level of a 10 Hz sinusoidal vibration such that it produced a degree of discomfort equivalent to that caused by a variety of multiple frequency stimuli including motions containing predominant beats and up to four sinusoidal components. The levels

L. C. FOTHERGILL; M. J. GRIFFIN

1977-01-01

344

Propagation of sinusoidal pulse laser beam in a plasma channel  

SciTech Connect

The propagation of an intense sinusoidal pulse laser beam, in a preformed plasma channel having a parabolic density profile, is analyzed. Considering a nonparaxial, nonlinear wave equation and using a variational technique, simultaneous equations describing the evolution of laser spot and pulse length are obtained. Numerical methods are used to study the effect of pulse length variation on betatron oscillations of the laser spot size as it propagates in the plasma channel. Approximate conditions for propagation of the laser pulse with a constant spot size and pulse length (matched beam propagation) are obtained.

Upadhyay, Ajay K.; Raj, Gaurav; Mishra, Rohit K.; Jha, Pallavi [Department of Physics, University of Lucknow, Lucknow 226007 (India)

2007-11-15

345

Room-temperature atmospheric argon plasma jet sustained with submicrosecond high-voltage pulses  

NASA Astrophysics Data System (ADS)

In this letter, an experimental study is presented to characterize a room-temperature plasma jet in atmospheric argon generated with submicrosecond voltage pulses at 4 kHz. Distinct from sinusoidally produced argon discharges that are prone to thermal runaway instabilities, the pulsed atmospheric argon plasma jet is stable and cold with an electron density 3.9 times greater than that in a comparable sinusoidal jet. Its optical emission is also much stronger. Electrical measurement suggests that the discharge event is preceded with a prebreakdown phase and its plasma stability is facilitated by the short voltage pulses.

Walsh, J. L.; Kong, M. G.

2007-11-01

346

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

PubMed Central

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.

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

1974-01-01

347

Allosteric Voltage Gating of Potassium Channels II  

PubMed Central

Large-conductance Ca2+-activated K+ channels can be activated by membrane voltage in the absence of Ca2+ binding, indicating that these channels contain an intrinsic voltage sensor. The properties of this voltage sensor and its relationship to channel activation were examined by studying gating charge movement from mSlo Ca2+-activated K+ channels in the virtual absence of Ca2+ (<1 nM). Charge movement was measured in response to voltage steps or sinusoidal voltage commands. The charge–voltage relationship (Q–V) is shallower and shifted to more negative voltages than the voltage-dependent open probability (G–V). Both ON and OFF gating currents evoked by brief (0.5-ms) voltage pulses appear to decay rapidly (?ON = 60 ?s at +200 mV, ?OFF = 16 ?s at ?80 mV). However, QOFF increases slowly with pulse duration, indicating that a large fraction of ON charge develops with a time course comparable to that of IK activation. The slow onset of this gating charge prevents its detection as a component of IgON, although it represents ?40% of the total charge moved at +140 mV. The decay of IgOFF is slowed after depolarizations that open mSlo channels. Yet, the majority of open channel charge relaxation is too rapid to be limited by channel closing. These results can be understood in terms of the allosteric voltage-gating scheme developed in the preceding paper (Horrigan, F.T., J. Cui, and R.W. Aldrich. 1999. J. Gen. Physiol. 114:277–304). The model contains five open (O) and five closed (C) states arranged in parallel, and the kinetic and steady-state properties of mSlo gating currents exhibit multiple components associated with C–C, O–O, and C–O transitions.

Horrigan, Frank T.; Aldrich, Richard W.

1999-01-01

348

Three-dimensional imaging of hepatic sinusoids in mice using synchrotron radiation micro-computed tomography.  

PubMed

Hepatic sinusoid, the smallest vessel in the liver, plays important roles in hepatic microcirculation. Although the structure of the hepatic sinusoids affects diverse functions of the liver, little is known about morphological alterations in the sinusoids under pathological conditions. In this study, we show that the structure of hepatic sinusoids can be identified three-dimensionally in normal and carbon tetrachloride-injured mouse liver, using the absorption mode of synchrotron radiation micro-computed tomography. We observed that the hepatic sinusoidal structure on tomographic slice images was similar to that on histological images of normal and acutely injured mice. Moreover, centrilobular necrosis and structural alterations of the sinusoids in the necrotic region were detectable on tomographic slice and volume-rendered images of the acutely injured mice. Furthermore, quantitative analyses on 3D volume-rendered images of the injured sinusoid revealed decrease in the volume of the sinusoid and connectivity of the sinusoidal network. Our results suggest that the use of synchrotron radiation micro-computed tomography may improve our understanding of the pathogenesis of hepatic diseases by detecting the hepatic sinusoids and their alterations in three-dimensional structures of the damaged liver. PMID:23861925

Yoon, Yae Jin; Chang, Soeun; Kim, Oh Youn; Kang, Bo-Kyeong; Park, Jaesung; Lim, Jae-Hong; Yun Huang, Jung; Kim, Yoon-Keun; Byun, Jae Ho; Gho, Yong Song

2013-07-05

349

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

DOEpatents

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.

Praeg, W.F.

1982-03-09

350

The Millimeter Wave Radiation of a Traveling Wave Sinusoidal Wire Antenna  

NASA Astrophysics Data System (ADS)

In this paper, investigation of radiation properties of the traveling-wave sinusoidal wire antennas is extended to the millimeter-wave frequencies (Ka-band) for the antennas whose geometrical dimensions vary in a wide range. Far-field patterns and S-parameters of composed three antenna sets were measured. A mathematical model was constructed for the structure and a MATLAB code based on this theoretical approach was written to calculate patterns, phase and attenuation constants of all investigated antennas. Frequency characteristics and the relation of antenna dimensions with wave parameters were investigated. Measured and calculated patterns were also compared with the constructed far-field patterns obtained by MoM (method of moments) and the MoM current distributions were used to explain the loss mechanisms of antennas. A directive, undistorted and smooth radiation can be achieved only choosing small undulated antennas whose peak-to-peak amplitude to period ratio ? is smaller than 0.4 (? < 0.4). It is shown that wavelength of broadside radiation is not equal to antenna period for all antennas, except for very small undulated antennas (? < 0.2). This antenna type can be used as a frequency-scan antenna for millimeter wave radars.

Salman, A. O.; Dibekci, D.; Gavrilov, S.; Vertiy, A. Alexei

2008-05-01

351

Sinusoidal ELF magnetic fields affect acetylcholinesterase activity in cerebellum synaptosomal membranes.  

PubMed

The effects of extremely low frequency magnetic fields (ELF-MF) on acetylcholinesterase (AChE) activity of synaptosomal membranes were investigated. Sinusoidal fields with 50 Hz frequency and different amplitudes caused AChE activity to decrease about 27% with a threshold of about 0.74 mT. The decrease in enzymatic activity was independent of the time of permanence in the field and was completely reversible. Identical results were obtained with exposure to static MF of the same amplitudes. Moreover, the inhibitory effects on enzymatic activity are spread over frequency windows with different maximal values at 60, 200, 350, and 475 Hz. When synaptosomal membranes were solubilized with Triton, ELF-MF did not affect AChE activity, suggesting the crucial role of the membrane, as well as the lipid linkage of the enzyme, in determining the conditions for inactivation. The results are discussed in order to give an interpretation at molecular level of the macroscopic effects produced by ELF-MF on biological systems, in particular the alterations of embryo development in many organisms due to acetylcholine accumulation. PMID:20041436

Ravera, Silvia; Bianco, Bruno; Cugnoli, Carlo; Panfoli, Isabella; Calzia, Daniela; Morelli, Alessandro; Pepe, Isidoro M

2010-05-01

352

Stream Segregation in the Perception of Sinusoidally Amplitude-Modulated Tones  

PubMed Central

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.

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

2012-01-01

353

A globally convergent frequency estimator  

Microsoft Academic Search

Online estimation of the frequency of a sinusoidal signal is a classical problem in systems theory that has many practical applications. In this paper the authors provide a solution to the problem of ensuring a globally convergent estimation. More specifically, they propose a new adaptive notch filter whose dynamic equations exhibit the following remarkable features: 1) all signals are globally

Liu Hsu; Romeo Ortega; G. Damm

1999-01-01

354

Frequency-domain SQUID multiplexing of transition-edge sensors  

Microsoft Academic Search

We describe our frequency-domain readout multiplexer for transition-edge sensor (TES) bolometers and present measurements of an eight-channel multiplexer. Each sensor is biased with a sinusoidal bias at a distinct frequency. As the sensor absorbs power, it amplitude-modulates its sinusoidal bias. Sensor currents are summed and measured with a single superconducting quantum interference device (SQUID) array. The SQUID array consists of

T. M. Lanting; Hsiao-Mei Cho; J. Clarke; M. A. Dobbs; W. L. Holzapfel; A. T. Lee; M. Lueker; P. L. Richards; A. D. Smith; H. G. Spieler

2005-01-01

355

Richtmyer-Meshkov Instability of a Membraneless, Sinusoidal Gas Interface  

NASA Astrophysics Data System (ADS)

Results are presented from a series of shock tube experiments studying the Richtmyer-Meshkov instability (RMI) for the case of a 2-D single mode gas interface. The membraneless interface is formed by the head-on flow of nitrogen, seeded with acetone, and sulfur-hexafluoride which creates a stagnation surface. A sinusoidal interface is created by oscillating two rectangular pistons that are initially flush with the shock tube walls. The RMI is studied for varying incident shock strengths (1.3 <=M <= 4) by imaging the interface with planar laser-induced fluorescence, once immediately before shock arrival and at two different post-shock times. The experimental images and the growth rates of non-dimensionalized geometrical features are compared to numerical simulations using the Raptor code (LLNL) which takes advantage of the Piecewise Linear Method (PLM) with Adaptive Mesh Refinement (AMR) to solve the Navier-Stokes equations.

Motl, Bradley

2005-11-01

356

Sinusoidal Cox Regression--A Rare Cancer Example  

PubMed Central

Evidence of an association between survival time and date of birth would suggest an etiologic role for a seasonally variable environmental exposure occurring within a narrow perinatal time period. Risk factors that may exhibit seasonal epidemicity include diet, infectious agents, allergens, and antihistamine use. Typically data has been analyzed by simply categorizing births into months or seasons of the year and performing multiple pairwise comparisons. This paper presents a statistically robust alternative, based upon a trigonometric Cox regression model, to analyze the cyclic nature of birth dates related to patient survival. Disease birth-date results are presented using a sinusoidal plot with peak date(s) of relative risk and a single P value that indicates whether an overall statistically significant seasonal association is present. Advantages of this derivative-free method include ease of use, increased power to detect statistically significant associations, and the ability to avoid arbitrary, subjective demarcation of seasons.

Efird, Jimmy Thomas

2010-01-01

357

Effect of interfacial viscosities upon displacement in sinusoidal capillaries  

SciTech Connect

This quantitative analysis shows the relative effects of interfacial tension, interfacial viscosities, and wetting during displacement in a capillary whose radius is a sinusoidal function of axial position. The effect of the interfacial viscosities is to increase the resistance to displacement regardless of the wetting condition. The results are consistent with a previous qualitative analysis and with a previous quantitative analysis for displacement in capillaries whose radii are independent of axial position. In screening surfactant systems for potential use in tertiary oil recovery, it is recommended that the interfacial tension be minimized first, since it determines whether oil displacement will occur, and that the interfacial viscosities be minimized second, since they influence the rate of oil displacement.

Giordano, R.M.; Slattery, J.C.

1987-10-01

358

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

Microsoft Academic Search

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

Yiqiao Liang; C. O. Nwankpa

1999-01-01

359

Generalized Techniques of Harmonic Elimination and Voltage Control in Thyristor Inverters: Part II --- Voltage Control Techniques  

Microsoft Academic Search

Theoretical techniques of voltage control for the half-bridge and full-bridge inverters are derived based on the results in [1]. Detailed analytical results for the symmetrical pulsewidth modulation method of voltage control are also presented. Voltage control techniques are derived whereby harmonic elimination is possible in variable-frequency variable-voltage three-phase inverter circuits. The technique for the half-bridge inverter is optimized subject to

Hasmukh S. Patel; Richard G. Hoft

1974-01-01

360

Digital sinusoidal PWMs for a micro-controller based single-phase inverter, Part 1: Principles of digital sinusoidal PWM generation  

Microsoft Academic Search

Nowadays, Digital Sinusoidal Pulse Width Modulation (DSPWM) is playing a major role in the generation of pure sinusoidal waveforms using micro-controller based inverters (Kawabata, Miyashita and Yamamoto 1991; Herrmann, Langer and Broeck 1993; Ying-Yu 1995; PICREF-1 1997; Shih-Liang, Meng-Yueh, Jin-Yi, Li-Chia and Ying-Y 1999; The Electrical Engineering Handbook 2000; Koutroulis, Chatzakis, Kalaitzakis and Voulgaris 2001; Skvarenina 2002; Pop, Chindris and

Matthew C. Trigg; Hooman Dehbonei; Chem V. Nayar

2008-01-01

361

Uncertainties in Adaptive Maximum Entropy Frequency Estimators.  

National Technical Information Service (NTIS)

For a real sinusoid in white noise, the weight vector noise associated with an adaptive maximum entropy frequency estimator causes the peak of the spectrum estimator to shift away from the input frequency. For a long adaptive filter and a normalized frequ...

R. J. Keeler

1979-01-01

362

On the 1\\/f noise and non-integer harmonic decay of the interaction of a finger sliding on flat and sinusoidal surfaces  

Microsoft Academic Search

Fluctuations of the frictional force arising from the stroke of a finger against flat and sinusoidal surfaces are studied. A custommade high-resolution friction force sensor, able to resolve millinewton forces, was used to record those fluctuations as well as the net, low-frequency components of the interaction force. Measurements show that the fluctuations of the sliding force are highly non-stationary. Despite

Michael Wiertlewski; Charles Hudin; Vincent Hayward

2011-01-01

363

Studies of combined effects of sinusoidal whole body vibrations and noise of varying bandwidths and intensities on TTS 2 in men  

Microsoft Academic Search

This study analyses the data from three laboratory experiments concerning the separate and combined effects on temporary threshold shifts in hearing (TTS2) of sinusoidal low-frequency (5 Hz — 2.12 m\\/s2 and 10 Hz —2.65 m\\/s2), whole body vibration (along the Z-axis), and continuous (white) noise with eight different bandwidths and intensity levels of 85 dB(A), 90 dB(A) and 98 dB(A).

Olavi Manninen

1983-01-01

364

Discrimination of interaural phase differences in the envelopes of sinusoidally amplitude-modulated 4kHz tones as a function of modulation depth  

Microsoft Academic Search

Psychometric functions were measured for the discrimination of the interaural phase difference (IPD) of the envelope of a sinusoidally amplitude-modulated (SAM) 4-kHz pure tone for modulation frequencies of 128 and 300 Hz and modulation depths (m) of 0.2, 0.6, 0.9, and 1.0. Contrary to recent modeling assumptions, it was found that a constant change in normalized interaural envelope correlation, with

Mark A. Stellmack; Neal F. Viemeister; Andrew J. Byrne

2005-01-01

365

Spline-based high-accuracy piecewise-polynomial phase-to-sinusoid amplitude converters.  

PubMed

We propose a method for direct digital frequency synthesis (DDS) using a cubic spline piecewise-polynomial model for a phase-to-sinusoid amplitude converter (PSAC). This method offers maximum smoothness of the output signal. Closed-form expressions for the cubic polynomial coefficients are derived in the spectral domain and the performance analysis of the model is given in the time and frequency domains. We derive the closed-form performance bounds of such DDS using conventional metrics: rms and maximum absolute errors (MAE) and maximum spurious free dynamic range (SFDR) measured in the discrete time domain. The main advantages of the proposed PSAC are its simplicity, analytical tractability, and inherent numerical stability for high table resolutions. Detailed guidelines for a fixed-point implementation are given, based on the algebraic analysis of all quantization effects. The results are verified on 81 PSAC configurations with the output resolutions from 5 to 41 bits by using a bit-exact simulation. The VHDL implementation of a high-accuracy DDS based on the proposed PSAC with 28-bit input phase word and 32-bit output value achieves SFDR of its digital output signal between 180 and 207 dB, with a signal-to-noise ratio of 192 dB. Its implementation requires only one 18 kB block RAM and three 18-bit embedded multipliers in a typical field-programmable gate array (FPGA) device. PMID:21507749

Petrinovi?, Davor; Brezovi?, Marko

2011-04-01

366

Non-sinusoidal phase modulations for improved performance of high power lasers  

Microsoft Academic Search

Spectral broadening is required on high power lasers to avoid Stimulated Brillouin Scattering in the laser chains and to smooth the focal spot. Up to now, spectral broadening has been obtained by sinusoidal phase modulations. However, it leads to non-homogeneous spectra, which is not optimal. In this paper we show that, thanks to non-sinusoidal phase modulations, performance of high power

Denis Penninckx; Steve Hocquet; Jean-François Gleyze; Claude Gouédard; Yves Jaouën

2010-01-01

367

Rate-distortion optimal sinusoidal modeling of audio and speech using psychoacoustical matching pursuits  

Microsoft Academic Search

In this paper, we propose a rate-distortion optimal algorithm for sinusoidal modeling of audio and speech. The algorithm uses a variable-length analysis window where the total number of sinusoids needed to model the source signal is optimally distributed over the segments. To account for human auditory perception, we use a new perceptually relevant distortion measure which is combined with the

Richard Heusdens; Steven van de Par

2002-01-01

368

Towards Large Eddy Simulations of Turbulent Drag Reduction Using Sinusoidal Riblets  

Microsoft Academic Search

A new modification to the drag reduction method using riblets is proposed, which consists of adding a sinusoidal variation to the riblet shape in spanwise direction. It is anticipated that more significant drag reduction will be achieved with sinusoidal riblets due to an oscillatory spanwise component added to the mean flow. First, Large Eddy Simulations of conventional riblet geometry consisting

YULIA PEET; PIERRE SAGAUT; YVES CHARRON

2007-01-01

369

Sinusoidal Pulse Width Modulation using CORDIC algorithm for Single Phase Matrix Converter  

Microsoft Academic Search

This paper presents the implementation of Sinusoidal Pulse Width Modulation (SPWM) on FPGA using Coordinate Rotation Digital Computer (CORDIC) algorithm for the application of Single Phase Matrix Converter (SPMC). The CORDIC is used here to replace common technique i.e Look-Up Table (LUT) technique in generating the sinusoidal wave used in SPWM. The SPWM has been implemented on ALTERA's Cyclone II

M. A. Rongi; A. Saparon; M. K. Hamzah

2010-01-01

370

Design of the Rotary Magnetic Position Sensor with the Sinusoidally Magnetized Permanent Magnet  

Microsoft Academic Search

This paper proposes the rotary magnetic position sensor (RMPS) which has the sinusoidally magnetized permanent magnet (PM) with a small number of poles. To make the sinusoidal magnetic flux density distribution from the PM, the magnetizing fixture is designed. And the magnetization process is analyzed using Preisach model coupled with 2D finite element method (FEM). Also the simulation result of

Seung-ho Jeong; Se-hyun Phyu; Byung-il Kwon

2006-01-01

371

Design of the Rotary Magnetic Position Sensor With the Sinusoidally Magnetized Permanent Magnet  

Microsoft Academic Search

This paper proposes a rotary magnetic position sensor (RMPS) which has a sinusoidally magnetized permanent magnet (PM) with a small number of poles. To make the sinusoidal magnetic flux density distribution from the PM, a magnetizing fixture is designed by adjusting its pole shape. The magnetization process is analyzed using the Preisach model and two-dimensional finite-element method (FEM). The simulation

Seung-Ho Jeong; Se-Hyun Rhyu; Byung-Il Kwon; Byung-Taek Kim

2007-01-01

372

Sinusoidal fringe projection system based on compact and non-mechanical scanning low-coherence Michelson interferometer for three-dimensional shape measurement  

NASA Astrophysics Data System (ADS)

We report a sinusoidal fringe projection system based on superluminiscent diode (SLD) as a broad-band light source in conjunction with an acousto-optic tunable filter (AOTF) as frequency tuning device for three-dimensional shape measurement. The present system is based on a compact low-coherence Michelson interferometer system. The conventional interferometric system was modified in which one side of the beam splitter was coated with aluminum oxide which is used as reference mirror. With this modified version, interference fringes can easily be obtained by simply placing the external mirror in contact on the other side of beam splitter. Sinusoidal fringes with multiple spatial-carrier frequency can be generated in real-time using the present system by means of changing the radio-frequency signal to AOTF electronically without mechanically moving any component in the system. The present system was tested by projecting the sinusoidal fringes on a step-like object and 3D shape of the object was reconstructed using Fourier transform fringe analysis technique. The main advantages of the proposed system are completely non-mechanical scanning, easy to align, high stability because of its nearly common-path geometry and compactness.

Anna, Tulsi; Dubey, Satish Kumar; Shakher, Chandra; Roy, Amitava; Mehta, Dalip Singh

2009-04-01

373

Deadbeat controlled PWM inverter with parameter estimation using only voltage sensor  

Microsoft Academic Search

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

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

1988-01-01

374

Single-Phase Voltage-Quadrupler Rectifier Using Only One Dual-Switch Power Module  

NASA Astrophysics Data System (ADS)

A single-phase voltage-quadrupler rectifier using only one dual-switch power module is presented. This is based on the half-bridge converter and the higher output voltage can easily be obtained by introducing the pumping action. The prototype, employing a power module with two insulated-gate bipolar transistors, is implemented. The experimental results under the current-mode control confirm that the input current can be wave-shaped sinusoidally with a near-unity power factor.

Itoh, Ryozo; Ishizaka, Kouichi; Neba, Yasuhiko; Matsumoto, Hirokazu; Haraguchi, Takahiro

375

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

Microsoft Academic Search

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

Olorunfemi Ojo

2004-01-01

376

DC ripple current reduction on a single-phase PWM voltage-source rectifier  

Microsoft Academic Search

A novel topology of single-phase pulsewidth modulation (PWM) voltage-source rectifier capable of achieving not only a sinusoidal input current, but also a zero-ripple output current, is presented. The rectifier consists of a conventional single-phase PWM voltage-source rectifier, a pair of additional switches and an inductor. Hence, the proposed rectifier requires neither a large DC capacitor nor a passive L-C resonant

Toshihisa Shimizu; Yasuhiro Jin; Gunji Kimura

2000-01-01

377

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

Microsoft Academic Search

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

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

1999-01-01

378

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

PubMed Central

We employ a Hodgkin-Huxley type model of basolateral ionic currents in bullfrog saccular hair cells to study 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 ionic currents. The model is demonstrated to exhibit a broad spectrum of autonomous rhythmic activity, including periodic and quasiperiodic 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 mechano-electrical transduction 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.

Dierkes, Kai; Lindner, Benjamin; Han, Lijuan; Shilnikov, Andrey L.

2011-01-01

379

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

PubMed Central

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.

2011-01-01

380

Tomographic Characterization of Aquifer Heterogeneity with a Sinusoidal Signal  

NASA Astrophysics Data System (ADS)

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.

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

2011-12-01

381

Multilevel cascade voltage source inverter with seperate DC sources  

DOEpatents

A multilevel cascade voltage source inverter having separate DC sources is described herein. This inverter is applicable to high voltage, high power applications such as flexible AC transmission systems (FACTS) including static VAR generation (SVG), power line conditioning, series compensation, phase shifting and voltage balancing and fuel cell and photovoltaic utility interface systems. The M-level inverter consists of at least one phase wherein each phase has a plurality of full bridge inverters equipped with an independent DC source. This inverter develops a near sinusoidal approximation voltage waveform with only one switching per cycle as the number of levels, M, is increased. The inverter may have either single-phase or multi-phase embodiments connected in either wye or delta configurations.

Peng, Fang Zheng (Knoxville, TN); Lai, Jih-Sheng (Blacksburg, VA)

2002-01-01

382

Multilevel cascade voltage source inverter with seperate DC sources  

DOEpatents

A multilevel cascade voltage source inverter having separate DC sources is described herein. This inverter is applicable to high voltage, high power applications such as flexible AC transmission systems (FACTS) including static VAR generation (SVG), power line conditioning, series compensation, phase shifting and voltage balancing and fuel cell and photovoltaic utility interface systems. The M-level inverter consists of at least one phase wherein each phase has a plurality of full bridge inverters equipped with an independent DC source. This inverter develops a near sinusoidal approximation voltage waveform with only one switching per cycle as the number of levels, M, is increased. The inverter may have either single-phase or multi-phase embodiments connected in either wye or delta configurations.

Peng, Fang Zheng (Oak Ridge, TN); Lai, Jih-Sheng (Knoxville, TN)

1997-01-01

383

Multilevel cascade voltage source inverter with separate DC sources  

DOEpatents

A multilevel cascade voltage source inverter having separate DC sources is described herein. This inverter is applicable to high voltage, high power applications such as flexible AC transmission systems (FACTS) including static VAR generation (SVG), power line conditioning, series compensation, phase shifting and voltage balancing and fuel cell and photovoltaic utility interface systems. The M-level inverter consists of at least one phase wherein each phase has a plurality of full bridge inverters equipped with an independent DC source. This inverter develops a near sinusoidal approximation voltage waveform with only one switching per cycle as the number of levels, M, is increased. The inverter may have either single-phase or multi-phase embodiments connected in either wye or delta configurations. 15 figs.

Peng, F.Z.; Lai, J.S.

1997-06-24

384

Specific gene delivery to liver sinusoidal and artery endothelial cells.  

PubMed

Different types of endothelial cells (EC) fulfill distinct tasks depending on their microenvironment. ECs are therefore difficult to genetically manipulate ex vivo for functional studies or gene therapy. We assessed lentiviral vectors (LVs) targeted to the EC surface marker CD105 for in vivo gene delivery. The mouse CD105-specific vector, mCD105-LV, transduced only CD105-positive cells in primary liver cell cultures. Upon systemic injection, strong reporter gene expression was detected in liver where mCD105-LV specifically transduced liver sinusoidal ECs (LSECs) but not Kupffer cells, which were mainly transduced by nontargeted LVs. Tumor ECs were specifically targeted upon intratumoral vector injection. Delivery of the erythropoietin gene with mCD105-LV resulted in substantially increased erythropoietin and hematocrit levels. The human CD105-specific vector (huCD105-LV) transduced exclusively human LSECs in mice transplanted with human liver ECs. Interestingly, when applied at higher dose and in absence of target cells in the liver, huCD105-LV transduced ECs of a human artery transplanted into the descending mouse aorta. The data demonstrate for the first time targeted gene delivery to specialized ECs upon systemic vector administration. This strategy offers novel options to better understand the physiological functions of ECs and to treat genetic diseases such as those affecting blood factors. PMID:23884859

Abel, Tobias; El Filali, Ebtisam; Waern, Johan; Schneider, Irene C; Yuan, Qinggong; Münch, Robert C; Hick, Meike; Warnecke, Gregor; Madrahimov, Nodir; Kontermann, Roland E; Schüttrumpf, Jörg; Müller, Ulrike C; Seppen, Jurgen; Ott, Michael; Buchholz, Christian J

2013-07-24

385

A high-efficiency CMOS voltage doubler  

Microsoft Academic Search

A charge pump cell is used to make a voltage doubler using improved serial switches. A complete power efficiency theory is presented which fits the measurements. The importance of capacitors is shown with plots of power efficiency versus load and stray capacitors. Several problems arising at low voltage or high frequency are developed and some optimizations are presented. The substrate

Pierre Favrat; Philippe Deval; Michel J. Declercq

1998-01-01

386

High Voltage Lines: Hazard at a Distance.  

ERIC Educational Resources Information Center

|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)|

Marino, Andrew A.; Becker, Robert O.

1978-01-01

387

A frequency domain method for analysis of dynamic circuits with resistive nonlinearities  

Microsoft Academic Search

Consider a dynamic circuit containing nonlinear resistors, the other elements being linear. Each nonlinear resistor is replaced by a set of equivalent sources which are current or voltage dependent. The parameters of these sources are corrected iteratively. In order to find the new controlling voltages (currents) linear sinusoidal problems are solved for source harmonics. The convergence of this iterative procedure

I. F. Hantila; F. Constantinescu; A. G. Gheorghe; M. Nitescu

2008-01-01

388

Analysis of the sinusoidal endothelial cell organization during the developmental stage of the fetal rat liver using a sinusoidal endothelial cell specific antibody, SE-1.  

PubMed

The sinusoid organization during the development of fetal rat livers was studied using a SE-1 antibody, which we have previously established as a specific monoclonal antibody against rat sinusoidal endothelial cell (SEC). Expression and localization of the SE-1 antigen in the liver tissues of 13- to 21-day-old fetuses were immunofluorescently and immunoelectron microscopically examined. The first positive fluorescence was observed in the immature liver of 15-day-old fetuses. The initial positive staining was randomly distributed in the liver parenchyma and showed no direct relation to the large vessels which may be derived from the fetal vitelline veins. The positive linear staining increased in number and connected with each other during the course of development. The SE-1 staining pattern and the sinusoidal arrangement became similar to those of the adult liver after 20th day of gestation. Immunoelectron microscopically, the immature SEC showed a weak positive reaction for the SE-1 antigen at their membrane and was observed together with immature hepatocytes and hematopoietic cells in the 15-day-old fetal liver. Along with the liver development, SEC formed a sinusoid structure closely associated with hepatocytes and came to strongly express the SE-1 antigen. These results indicate that the organization of the hepatic sinusoid may start at around 15th day of the gestation and occurs randomly in the fetal liver parenchyma. It is also suggested that the expression of SE-1 antigen is possibly regulated by the intimate association with hepatocytes. PMID:10206736

Morita, M; Qun, W; Watanabe, H; Doi, Y; Mori, M; Enomoto, K

1998-12-01

389

30 CFR - Voltage Longwalls  

Code of Federal Regulations, 2010 CFR

...STANDARDS-UNDERGROUND COAL MINES Underground High-Voltage Distribution § 75.812-2 High-voltage power centers and transformers; record...in a book approved by the Secretary. High-Voltage Longwalls Source: 67 FR 11001,...

2010-07-01

390

Area Modulation Grating for Sinusoidal Structure Illumination on Phase-Measuring Profilometry  

NASA Astrophysics Data System (ADS)

Sinusoidal structured illumination is used widely in three-dimensional (3-D) sensing and machine vision. Phase algorithms, for example, in phase-measuring profilometry, are inherently free of errors only with perfect sinusoidal fringe projection. But it is difficult to produce a perfect sinusoidal grating. We propose a new concept, area modulation, to improve the sinusoidality of structured illumination. A binary-coded picture is made up of many micrometer units. An aperture is open in every micrometer unit, and its area is determined by the value of the sinusoidal function. When such a grating is projected onto an object surface, the image of the grating becomes sinusoidal because of the convolution function of an optical system. We have designed and manufactured an area modulation grating for sinusoidal structure illumination using a large-scale integration technique. The area modulation grating has been used in the high-precision phase-measuring profilometry system, and the phase errors caused by the area modulation grating are reduced to 0.1%. The grating guaranteed the entire measuring accuracy to a 1% equivalent wavelength. The experimental results proved that area modulation grating would be of significant help in improving the phase-measurement accuracy of the 3-D sensing system.

Xian, Tao; Su, Xianyu

2001-03-01

391

Frequency lowering processing for listeners with significant hearing loss  

Microsoft Academic Search

Many listeners with medium-severe hearing loss present audiograms with high frequency loss descending profiles. These patients can resolve spectral cues normally for lower frequency signals but they often show less ability to use high frequency information. We have presented in this paper a new processing algorithm based on a sinusoidal speech model which results is lowered and sharpened speech. Preliminary

C. M. Aguileru Mutioz; P. B. Nelson; J. C. Rutledge; A. Gago

1999-01-01

392

Investigation of voltage swell mitigation using STATCOM  

NASA Astrophysics Data System (ADS)

STATCOM is one of the best applications of a self commutated FACTS device to control power quality problems in the distribution system. This project proposed a STATCOM model with voltage control mechanism. DQ transformation was implemented in the controller system to achieve better estimation. Then, the model was used to investigate and analyse voltage swell problem in distribution system. The simulation results show that voltage swell could contaminate distribution network with unwanted harmonic frequencies. Negative sequence frequencies give harmful effects to the network. System connected with proposed STATCOM model illustrates that it could mitigate this problems efficiently.

Razak, N. A. Abdul; >S Jaafar, I. S.

2013-06-01

393

Procedure for Deconvolution of Time-Dependent Signals with Sinusoidal Shape  

SciTech Connect

The present paper deals with development of the deconvolution procedure of two time-dependent signals with sinusoidal shape in order to extract the genuine optogalvanic signal from the registered one in hollow cathode glow discharge.

Todorov, M. D. [Faculty of Applied Mathematics and Informatics, Technical University of Sofia, 1000 Sofia (Bulgaria); Djulgerova, R.; Mihailov, V. [Institute of Solid State Physics, Bulgarian Academy of Sciences, 1784 Sofia (Bulgaria); Koperski, J. [Institute of Physics, Jagellonian University, 30-059 Krakow (Poland)

2008-10-30

394

Fabrication and Metrology of Micro-Scale Sinusoidal Surfaces in Polymer Workpiece Materials  

SciTech Connect

This study investigates the fabrication of precision, micro-scale sinusoidal surfaces in polymer workpiece materials and discusses methods to quantitatively characterize these surfaces. These precision sinusoidal surfaces are an important feature in a mesoscale assembly that will be used as part of a physics experiment. The experiment will study the formation of Rayleigh Taylor instabilities and requires a sinusoidal surface with an amplitude of 2.5 {micro}m and a wavelength of 70.7 {micro}m in both the x- and y-directions. The sinusoids must have sub-{micro}m form accuracy with a surface finish on the order of 100 nm, and they must be produced in a workpiece consisting of adjacent pieces of polyimide and iodine-doped polystyrene, a portion of which is illustrated in Figure 1.

Bono, M J; Hibbard, R L

2004-08-02

395

Comparative Study of the Rayleigh Hypothesis and Analytic Continuation Methods as Applied to Sinusoidal Gratings.  

National Technical Information Service (NTIS)

Two methods are investigated for solving the problem of plane-wave diffraction by gratings with sinusoidal profiles. The first is based on an extension of the Rayleigh hypothesis, and the second employs an analytic continuation technique for computing the...

R. Mittra T. Itoh V. Jamnejad-Dailami

1971-01-01

396

Scintillations Associated with Bottomside Sinusoidal Irregularities in the Equatorial F Region.  

National Technical Information Service (NTIS)

A new category of equatorial F region plasma irregularities characterized by nearly sinusoidal wave forms in the ion number density N sub i was observed by the Atmosphere Explorer satellites. Multisatellite scintillation observations made at Huancayo, Per...

S. Basu S. Basu C. E. Valladares A. DasGupta H. E. Whitney

1986-01-01

397

Scintillations associated with bottomside sinusoidal irregularities in the equatorial F region  

SciTech Connect

A new category of equatorial F region plasma irregularities characterized by nearly sinusoidal wave forms in the ion number density N/sub i/ was observed by the Atmosphere Explorer satellites. Multisatellite scintillation observations made at Huancayo, Peru and spaced-receiver drive measurements made at Ancon, Peru are associated with such irregularities observed by AE-E on a few nights in December 1979. The scintillations continue for a period of almost 6 hours, at a level that varies from moderate to fairly intense (S4 = 0.1-0.8 at 250 MHz), and these S4 fluctuations are quite well correlated, even over a distance of 1000 km. The irregularities constituting the large patch are found to drift eastward at a velocity of approximately 140 m/s. This and other such events are accompanied by the frequency spread signatures on Huancayo ionograms, as previously reported. The unique feature of the Fourier spectra associated with such bottomside sinusiodal (BSS) irregularities is the presence of Fresnel oscillations, which allow a determination of the velocity of the diffraction pattern perpendicular to the direction of the ray from the satellite to the ground station. The velocity so determined agrees well with the results of simultaneously performed spaced-receiver drift measurements. The presence of Fresnel oscillations indicates that the BSS irregularities occur in a relatively thin layer. However, while the scintillation data indicate a high frequency, roll off with a spectral index of the order of -3 to -4, the in-situ data tend to indicate that the index is of the order -5 to -6. Modeling studies are necessary to resolve this difference.

Valladares, C.E.; DasGupta, A.; Whitney, H.E.

1986-01-01

398

The Detuning Characteristics of Rational Harmonic Mode-Locked Semiconductor Optical Amplifier Fiber-Ring Laser Using Backward Optical Sinusoidal-Wave Injection Modulation  

NASA Astrophysics Data System (ADS)

The modulation waveform, power, and frequency detuning dynamics of a semiconductor optical amplifier fiber-ring laser (SOAFL) harmonic and rational-harmonic mode-locked by using backward injection of a large-signal sinusoidal-wave modulated Fabry-Pérot laser diode (FPLD) are studied. The shortest pulsewidth of 53.3 ps at 1 GHz with spectral linewidth of 0.09 nm at modulation power of 17 dBm can be obtained, which corresponds to a time-bandwidth product of 2.8. The threshold modulation power and the maximum frequency detuning range for harmonic mode-locking of the SOAFL are 11.5 dBm and 180 kHz, respectively. The mode-locked SOAFL gradually recovers back to sinusoidal-wave modulation mode at the detuning frequency beyond +/- 400 kHz. The pulse broadening slopes for the positive-and negative-frequency detuning regions of 0.48 and 0.375 ps/kHz are determined, respectively. By enlarging the modulating power and detuning the modulation frequency of FPLD, the SOAFL can be rational-harmonic mode-locked up to 12 GHz with 33-ps pulsewidth.

Lin, Gong-Ru; Hsueh, Pai-Shen; Wu, Hsiao-Hua; Liao, Yu-Sheng

2005-03-01

399

Application of synergetic control theory to non-sinusoidal PMSMs via multiple reference frame theory  

Microsoft Academic Search

Park equations in a rotor reference frame are used for sinusoidal back-electromotive force (EMF) permanent magnet synchronous machines (PMSMs) to eliminate the rotor-position dependency and create time-invariant model. However, Park equations are not suitable for non-sinusoidal back EMF cases. Instead, multiple reference frames are considered individually for each harmonic, with their rotation speed defined as multiples of the rotor electrical

Ali Davoudi; Ali M. Bazzi; Patrick L. Chapman

2008-01-01

400

Strength evaluations of sinusoidal core for FRP sandwich bridge deck panels  

Microsoft Academic Search

Fiber-reinforced polymer (FRP) sandwich deck panels with sinusoidal core geometry have shown to be successful both in new construction and the rehabilitation of existing bridge decks. This paper is focused on an experimental study of the strength evaluations of a honeycomb sandwich core under out-of-plane compression and transverse shear. The sinusoidal core is made of E-glass Chopped Strand Mat (ChSM)

An Chen; Julio F. Davalos

2010-01-01

401

Effects of low-temperature ozone annealing on current-voltage and low-frequency noise characteristics of [100]-tilt YBa2Cu3O7-X grain-boundary Josephson junctions  

NASA Astrophysics Data System (ADS)

The dc and noise characteristics of YBa2Cu3O7-X [100]-tilt bicrystal Josephson junctions have been studied before and after annealing in ozone. Junctions with a misorientation angle 2×14° have been characterized in the temperature range from 7 K to 75 K, and their IcRn-product values were equal up to 5.4 mV at 7 K. Ozone annealing of the junctions at 140°C results in a two-fold decrease of the normal-state resistances Rn. The values of the IcRn-product have been increased not more than 7% after annealing. The spectral densities SV(f) of the voltage fluctuations measured at various currents were of 1/f? -type with ? = 0.8-1.0. The normalized spectral densities Sr(f) = Sr(f)/Rn2 and Si(f) = SIc(f)/Ic2 of normal-state resistance fluctuations ?Rn and critical current fluctuations ?Ic, respectively, plus a coefficient k of the correlation between ?Rn and ?Ic fluctuations have been derived from the measured spectra SV(f) before and after annealing. The modification of transport and noise characteristics were consistent with a junction model of the [100]-tilt junction, where the supercurrent and quasiparticle current flow through the same junction area, the annealing in ozone results in a decrease of the barrier thickness and the barrier is free from localized states. We suggest that the low-frequency noise arises at the interface between superconductor and the barrier.

Liatti, M. V.; Divin, Y. Y.; Poppe, U.; Gubankov, V. N.; Urban, K.

2006-06-01

402

Beam induced rf cavity transient voltage  

SciTech Connect

The authors calculate the transient voltage induced in a radio frequency cavity by the injection of a relativistic bunched beam into a circular accelerator. A simplified model of the beam induced voltage, using a single tone current signal, is generated and compared with the voltage induced by a more realistic model of a point-like bunched beam. The high Q limit of the bunched beam model is shown to be related simply to the simplified model. Both models are shown to induce voltages at the resonant frequency {omega}{sub r} of the cavity and at an integer multiple of the bunch revolution frequency (i.e. the accelerating frequency for powered cavity operation) h{omega}{sub {omicron}}. The presence of two nearby frequencies in the cavity leads to a modulation of the carrier wave exp(h{omega}{sub {omicron}}t). A special emphasis is placed in this paper on studying the modulation function. These models prove useful for computing the transient voltage induced in superconducting rf cavities, which was the motivation behind this research. The modulation of the transient cavity voltage discussed in this paper is the physical basis of the recently observed and explained new kinds of longitudinal rigid dipole mode which differs from the conventional Robinson mode.

Kramer, S.L.; Wang, J.M. [Brookhaven National Lab., Upton, NY (United States)

1998-10-01

403

BEAM INDUCED RF CAVITY TRANSIENT VOLTAGE  

SciTech Connect

The authors calculate the transient voltage induced in a radio frequency cavity by the injection of a relativistic bunched beam into a circular accelerator. A simplified model of the beam induced voltage, using a single tone current signal, is generated and compared with the voltage induced by a more realistic model of a point-like bunched beam. The high Q limit of the bunched beam model is shown to be related simply to the simplified model. Both models are shown to induce voltages at the resonant frequency w{sub r} of the cavity and at an integer multiple of the bunch revolution frequency (i.e. the accelerating frequency for powered cavity operation) hw{sub o}. The presence of two near-by frequencies in the cavity leads to a modulation of the carrier wave exp(jhw{sub o}t). A special emphasis is placed in this paper on studying the modulation function. These models prove useful for computing the transient voltage induced in superconducting rf cavities, which was the motivation behind this research. The modulation of the transient cavity voltage discussed in this paper is the physical basis of the recently observed and explained new kind of longitudinal rigid dipole mode which differs from the conventional Robinson mode.

KRAMER,S.L.; WANG,J.M.

1998-11-01

404

Effects of old age on vascular complexity and dispersion of the hepatic sinusoidal network  

PubMed Central

Objectives In old age, there are marked changes in both the structure of the liver sinusoidal endothelial cell and liver perfusion. The objective of this study was to determine whether there are also aging changes in the microvascular architecture and vascular dispersion of the liver that might influence liver function. Methods Vascular corrosion casts and light micrographs of young (4 mths) and old (24 mths) rat livers were compared. Fractal and Fourier analyses, and microcomputed tomography were used. Vascular dispersion was determined from the dispersion number for sucrose and 100 nm microspheres in impulse response experiments. Results Age did not affect sinusoidal dimensions, sinusoidal density or dispersion number. There were changes in the geometry and complexity of the sinusoidal network as determined by Fractal dimension and degree of anisotropy. Conclusions There are small age-related changes in the architecture of the liver sinusoidal network, which may influence hepatic function and reflect broader aging changes in the microcirculation. However sinusoidal dimensions and hepatic vascular dispersion are not markedly influenced by old age.

Warren, Alessandra; Chaberek, Slawomir; Ostrowski, Kazimierz; Cogger, Victoria C.; Hilmer, Sarah N.; McCuskey, Robert S.; Fraser, Robin; Le Couteur, David G.

2011-01-01

405

Application of the Josephson effect to voltage metrology  

Microsoft Academic Search

The unique ability of a Josephson junction to control the flow of magnetic flux quanta leads to a perfect relationship between frequency and voltage. Over the last 30 years, metrology laboratories have used this effect to greatly improve the accuracy of dc voltage standards. More recent research is focused on combining the ideas of digital signal processing with quantum voltage

SAMUEL P. BENZ; CLARK A. HAMILTON

2004-01-01

406

High-accuracy sinusoidal phase-modulating self-mixing interferometer using an electro-optic modulator: development and evaluation.  

PubMed

A sinusoidal phase-modulating He-Ne laser subject to weak optical feedback has been used to develop an interferometer that is capable of performing real-time displacement measurement with nanometer accuracy. The principle and the signal processing method are introduced. A commercial dual-frequency interferometer is included in the displacement measurement in both small and large ranges to evaluate the performance of the developed interferometer. Experimental results show that the average errors and standard deviations of the interferometer are in good agreement with data obtained from the commercial interferometer. The resolution and the multiple feedback effect of the interferometer are discussed in detail. These results show that the development of the interferometer is reasonable and feasible. PMID:23385942

Xia, Wei; Wang, Ming; Yang, Zhenyu; Guo, Wenhua; Hao, Hui; Guo, Dongmei

2013-02-01

407

Analytical study on the three-dimensional temperature field of KDP crystal irradiated by sinusoidal modulated laser  

NASA Astrophysics Data System (ADS)

A general analytical transient temperature field expression of KDP crystal irradiated by sinusoidal modulated laser is obtained by the integral transform method, based on the heat conduction equation of the orthotropic material. The influence of radius, power and frequency of the laser on the transient temperature field of KDP crystal is simulated by Matlab. The results show that the temperature of material has stepwise distribution with time, which shows periodical stable distribution after some time, and it increases with the decrease of the laser radius and the increase of the laser power. The above results provide a theoretical basis for the photothermal displacement technology used in the measurement of the opto-thermal parameters of the KDP crystal.

Zhang, Yingcong; Shen, Hua; Zhu, Rihong

2013-06-01

408

Booster synchrotron frequency below transition  

SciTech Connect

The dipole mode synchrotron frequency is a basic beam parameter; it and a few similarly basic quantities measured at small time intervals serve to characterize the longitudinal beam dynamics throughout the acceleration cycle. The effective accelerating voltage, in conjunction with the amount of rf voltage required for the acceleration, is important for the estimate of the beam energy loss per turn. The dipole mode frequency can be used to obtain the effective accelerating rf voltage, providing that it can be measured precisely. The synchrotron frequency measured from the synchrotron phase detector signal (SPD) generally agrees well with calculation, and it can be applied for such purposes as inferring the effective rf voltage.

Xi Yang et al.

2004-04-21

409

Ultra-High-Frequency Oscillography  

Microsoft Academic Search

Starting from the transit-time effects of the first and second kind, occurring in a cathode-ray tube, two methods are described for the oscillographic examination of ultra-high-frequency oscillations. First, we have the inversion spectrograph which supplies, by means of a white and spectrally dispersed electron beam, sinusoidal and complex inversion spectrograms. Second, we may use ultradynamic Lissajous figures which differ from

H. E. Hollmann

1940-01-01

410

Profile-based Optimization of Power Performance by using Dynamic Voltage Scaling on a PC cluster  

Microsoft Academic Search

Currently, several of the high performance processors used in a PC cluster have a DVFS (Dynamic Voltage and Frequency Scaling) architecture that can dynamically scale processor voltage and frequency. Adaptive scheduling of the voltage and frequency enables us to reduce power dis- sipation without a performance slowdown during commu- nication and memory access. In this paper, we propose a method

Yoshihiko Hottay; Mitsuhisa Sato; Hideaki Kimura; Satoshi Matsuoka; Taisuke Boku; Daisuke Takahashi

411

Current-Voltage Characteristics Of Atmospheric Pressure Plasma Jet  

NASA Astrophysics Data System (ADS)

We have constructed a plasma jet that can operate in the frequency range 25-150 kHz and within the range of 5-10 kV of applied peak-to-peak voltages. High voltage probes are used in order to obtain current and voltage waveforms. In this paper, we will show VRMS-IMRS plasma jet characteristics for the working frequency of 80 kHz. Current and voltage measurements were made both for the increase and decrease of the applied voltage in order to see if there is a hysteresis effect.

Puac, N.; Maletic, D.; Lazovic, S.; Malovic, G.; Dordevic, A.; Petrovic, Z. Lj.

2010-07-01

412

New types of transformer frequency dividers  

Microsoft Academic Search

Conclusions The dividers described above can be made for dividing high voltages (2–3.5 kV) over a wide frequency range (20 Hz–200 kHz). The divider with its variable input resistance provides a convenient and rapid reading of the input voltage for a known output voltage and, owing to this, it can be used in thermoelectric voltage comparators.

T. B. Rozhdestvenskaya; V. M. Baikov

1972-01-01

413

Measurement of space-charge distributions in solid insulators under rapidly varying voltage using the high-voltage, high-speed pulsed electro-acoustic (PEA) apparatus  

NASA Astrophysics Data System (ADS)

A new high-voltage, high-speed pulsed electro-acoustic (PEA) apparatus for real-time measurements of space-charge distribution in solid insulators subjected to rapidly varying voltages is described. Very high-rate PEA measurement is accomplished with the use of a high-speed real-time data acquisition module known as the `Eclipse' unit and a purpose-built high-voltage FET switch pulse generator. Real-time space-charge measurements with good phase resolving capability can be made under time varying applied stresses, e.g. voltage transients or ac conditions. The high-field PEA system has been used to investigate the space-charge dynamics in polyethylene samples stressed by 0.2 and 50 Hz sinusoidal ac voltages.

See, A.; Fothergill, J. C.; Dissado, L. A.; Alison, J. M.

2001-08-01

414

Adaptive voltage position design for voltage regulators  

Microsoft Academic Search

This paper proposes a general design guideline for the voltage regulator (VR) to achieve adaptive voltage position (AVP). All existing control methods are covered for different kinds of output filter capacitors. Based on the small-signal model analysis, the output impedance and system control bandwidth are discussed. Following the proposed design guidelines, simulation and experimental results demonstrate very good VR transient

Kaiwei Yao; Yuancheng Ren; Julu Sun; Kisun Lee; Ming Xu; Jinghai Zhou; Fred C. Lee

2004-01-01

415

30 CFR 75.832 - Frequency of examinations; recordkeeping.  

Code of Federal Regulations, 2013 CFR

...STANDARDS-UNDERGROUND COAL MINES Underground High-Voltage Distribution High-Voltage Longwalls § 75.832 Frequency of examinations...7 days, a qualified person must examine each high-voltage continuous mining machine to verify...

2013-07-01

416

Respiration and medullary blood flow during sinusoidal hypoxia in the peripherally chemodenervated cat.  

PubMed

The hypothesis that hypoxic respiratory depression is mediated by changes in medullary blood flow (MBF) was assessed in 18 anesthetized, paralyzed, vagotomized, peripherally chemodenervated, ventilated cats exposed to sinusoidal hypoxic hypoxia. In nine cats, the dynamic response of the central respiratory controller to hypoxia was studied by varying the cycle time of sinusoidal hypoxia (cycle time = 2.5, 4, 6, 10, and 15 min). Peak phrenic neurogram amplitude (PNA) followed sinusoidal oscillations in the hypoxic input [arterial O2 saturation (SaO2)] at all cycle times. The relationship between PNA and SaO2 was expressed as the transfer function of the system and was approximated as a first-order differential equation with a time constant of 78 +/- 1 s, a value consistent with a previous measurement of the time constant of the change in respiration following a change in brain blood flow. In a separate study, MBF was continuously measured during sinusoidal hypoxia (cycle time = 6 min; n = 9) with a laser-Doppler flow probe to directly assess the role of MBF in production of hypoxic respiratory depression. PNA and MBF followed SaO2 oscillations during sinusoidal hypoxia. Infusion of sodium nitroprusside (20 micrograms.kg-1.min-1 iv) increased MBF by 30-40% and abolished MBF oscillations during subsequent sinusoidal hypoxia but had no effect on PNA oscillations. We conclude that the increase in brain blood flow seen during sinusoidal hypoxia is not the primary cause of the accompanying central hypoxic respiratory depression. PMID:8760208

Yu, Q P; Melton, J E; Neubauer, J A; Edelman, N H

1996-07-01

417

Fire Patterns of HH Neuron under External Sinusoidal ELF Stimulus  

Microsoft Academic Search

Neuron as the main information carrier in neural systems is able to generate diverse fire trains in response to different stimuli. In this paper, the stimulus frequency is taken as the bifurcation parameter, and the ISI is considered to be one of the state variables. Via numerical simulation, we mainly concentrate on investigating the kinds of fire patterns that the

Han Chunxiao; Wang Jiang; Li Huiyan

2007-01-01

418

Multilevel inverter modulation schemes to eliminate common-mode voltages  

Microsoft Academic Search

It is well known that conventional two-level pulsewidth modulated (PWM) inverters generate high-frequency common-mode voltages with high dv\\/dt. Similarly, commonly used multilevel inverter modulation schemes generate common-mode voltages. Common-mode voltages may cause motor shaft voltages and bearing currents and conducted electromagnetic interference (EMI). Premature motor bearing failures and electronic equipment malfunctions have been reported to be directly related to bearing

Haoran Zhang; Annette von Jouanne; Shaoan Dai; Alan K. Wallace; Fei Wang

2000-01-01

419

Polyphase Induction Motor Performance and Losses on Nonsinusoidal Voltage Sources  

Microsoft Academic Search

Induction motors excited with static frequency converters almost invariably are subjected to nonsinusoidal voltage waveforms, and the presence of time harmonics in the applied voltage results in currents at the harmonic frequencies. These currents result in additional and sometimes rather large losses. A method for calculating these harmonic currents and losses is presented, and experimental data are included to substantiate

Eugene Klingshirn; Howard Jordan

1968-01-01

420

Liver Sinusoidal Endothelial Cells Are a Site of Murine Cytomegalovirus Latency and Reactivation?  

PubMed Central

Latent cytomegalovirus (CMV) is frequently transmitted by organ transplantation, and its reactivation under conditions of immunosuppressive prophylaxis against graft rejection by host-versus-graft disease bears a risk of graft failure due to viral pathogenesis. CMV is the most common cause of infection following liver transplantation. Although hematopoietic cells of the myeloid lineage are a recognized source of latent CMV, the cellular sites of latency in the liver are not comprehensively typed. Here we have used the BALB/c mouse model of murine CMV infection to identify latently infected hepatic cell types. We performed sex-mismatched bone marrow transplantation with male donors and female recipients to generate latently infected sex chromosome chimeras, allowing us to distinguish between Y-chromosome (gene sry or tdy)-positive donor-derived hematopoietic descendants and Y-chromosome-negative cells of recipients' tissues. The viral genome was found to localize primarily to sry-negative CD11b? CD11c? CD31+ CD146+ cells lacking major histocompatibility complex class II antigen (MHC-II) but expressing murine L-SIGN. This cell surface phenotype is typical of liver sinusoidal endothelial cells (LSECs). Notably, sry-positive CD146+ cells were distinguished by the expression of MHC-II and did not harbor latent viral DNA. In this model, the frequency of latently infected cells was found to be 1 to 2 per 104 LSECs, with an average copy number of 9 (range, 4 to 17) viral genomes. Ex vivo-isolated, latently infected LSECs expressed the viral genes m123/ie1 and M122/ie3 but not M112-M113/e1, M55/gB, or M86/MCP. Importantly, in an LSEC transfer model, infectious virus reactivated from recipients' tissue explants with an incidence of one reactivation per 1,000 viral-genome-carrying LSECs. These findings identified LSECs as the main cellular site of murine CMV latency and reactivation in the liver.

Seckert, Christof K.; Renzaho, Angelique; Tervo, Hanna-Mari; Krause, Claudia; Deegen, Petra; Kuhnapfel, Birgit; Reddehase, Matthias J.; Grzimek, Natascha K. A.

2009-01-01

421

Mixed Voltage VLSI Design.  

National Technical Information Service (NTIS)

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 ...

R. Panwar D. Rennels L. Alkalaj

1993-01-01

422

Automatic voltage imbalance detector  

DOEpatents

A device for indicating and preventing damage to voltage cells such as galvanic cells and fuel cells connected in series by detecting sequential voltages and comparing these voltages to adjacent voltage cells. The device is implemented by using operational amplifiers and switching circuitry is provided by transistors. The device can be utilized in battery powered electric vehicles to prevent galvanic cell damage and also in series connected fuel cells to prevent fuel cell damage.

Bobbett, Ronald E. (Los Alamos, NM); McCormick, J. Byron (Los Alamos, NM); Kerwin, William J. (Tucson, AZ)

1984-01-01

423

Adaptive modified Newton algorithm for multiple frequencies estimation  

Microsoft Academic Search

In this paper, we study the problem of adaptive retrieval of multiple sinusoids in white noise. It is shown that frequency estimation problem can be reformulated as an unconstrained optimization problem. Based on the proposed cost function, we derive a new adaptive quasi-Newton algorithm for tracking frequencies by approximating Hessian matrix appropriately, which not only significantly reduces the computation complexity,

Jian Yang; Hongsheng Xi; Feng Yang

2008-01-01

424

NDE for Metals, Composites and Semiconductors by Frequency Modulated Thermography  

Microsoft Academic Search

Active thermography is a relatively new NDE technique, in which either a pulse or sinusoidal thermal stimulus forms the basis for conventional Pulsed (PT) and Pulsed Phase (PPT), and Lock-in (LT) Thermography respectively. Recently a new approach to active thermography was proposed in which the thermal stimulus is frequency modulated. In Frequency Modulated Thermal Wave Imaging (FMTWI), a specimen is

S. Tuli; R. Mulaveesala

2006-01-01

425

IGBT high frequency operation  

Microsoft Academic Search

IGBT (insulated gate bipolar transistor) devices have been designed into low frequency (<20 kHz) power controls for many types of equipment. This equipment includes: high voltage applications such as 120 V to 440 V motor controls; AC power line conditioning; and automotive ignition systems. It can be quite disconcerting to have an IGBT power control design that generates radio frequency

R. J. Valentine

1996-01-01

426

Stereo channels with different temporal frequency tunings.  

PubMed

To investigate the spatial and temporal frequency tunings for stereopsis, we measured the contrast sensitivity for depth discrimination with variable spatiotemporal frequencies and disparities using drifting sinusoidal gratings. The results showed that the contrast sensitivity changed with the stimulus disparity and the disparity tuning function varied with the spatial frequency. The disparity in the peak sensitivity decreased proportionally with the spatial frequency (size-disparity correlation). Although the temporal frequency exhibited a limited influence on the peak disparity, the temporal frequency tuning varied with the spatial frequency. The shape of the temporal frequency tuning function was lowpass for higher spatial frequencies, whereas it was bandpass for low spatial frequencies. These results suggest that more than one channel with different temporal as well as spatial frequency tunings contribute to stereopsis. PMID:17184805

Lee, Seungbae; Shioiri, Satoshi; Yaguchi, Hirohisa

2006-12-20

427

Nonlinear electrokinetics at large voltages  

NASA Astrophysics Data System (ADS)

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.

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

2009-07-01

428

High-power-factor electronic ballast with constant DC-link voltage  

Microsoft Academic Search

This paper presents a high-power-factor (HPF) electronic ballast based on a single power processing stage with constant DC-link voltage. The switching frequency is controlled to maintain the DC-link voltage and the voltage across the switches constant, independently of changes in the AC-input voltage. This control method assures zero-voltage switching (ZVS) for the specified AC-input-voltage range. Besides, with an appropriate design

Ricardo de Oliveira Brioschi; J. L. F. Vieira

1998-01-01

429

Recent advances in liver sinusoidal endothelial ultrastructure and fine structure immunocytochemistry.  

PubMed

Ultrastructure reports have described that liver sinusoidal endothelial cell (LSEC)s contain a cytoskeletal framework of filamentous actin. Small G protein has emerged as an important regulator of the actin cytoskeleton, and consequently, of cell morphology and motility. We investigated actin filaments in relation to SEF in LSECs using a heavy meromyosin-decorated reaction and thereby elucidated the roles of small G protein and actin cytoskeleton in the morphological and functional alterations of SEF. Caveolin-1 expression has also been found in fenestrations with many characteristics of liver sinusoidal endothelial cells. Currently, fenestral studies and human disease are revealing ways to increase the liver sieve's porosity, which is reduced through pathological mechanisms. Hepatic sinusoidal endothelial dysfunction, which is known to impair endothelium-dependent relaxation in the liver microcirculation, contributes to increased intrahepatic vascular resistance. PMID:21906955

Yokomori, Hiroaki; Oda, Masaya; Yoshimura, Kazunori; Hibi, Toshifumu

2011-08-11

430

The Integrity bare-metal stent made by continuous sinusoid technology.  

PubMed

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

Turco, Mark A

2011-05-01

431

Dactinomycin-induced Hepatic Sinusoidal Obstruction Syndrome Responding to Treatment with N-acetylcysteine  

PubMed Central

Hepatic sinusoidal obstruction syndrome is commonly described in pediatric oncology as a complication of chemotherapy. It has also been occasionally reported in adult cancer patients. Treatment is largely supportive with fluid restriction. A 16-month-old girl with stage II Wilms tumor receiving post-nephrectomy chemotherapy with dactinomycin and vincristine developed hepatic sinusoidal obstruction syndrome with painful hepatomegaly, ascites with significant weight gain, grossly deranged liver function, severe thrombocytopenia, and reversal of blood flow in the portal vein on Doppler sonography. Treatment with N-acetylcysteine was followed by complete resolution of clinical signs and amelioration of laboratory abnormalities within 72 hours of treatment. N-acetylcysteine is a safe and probably an effective treatment for dactinomycin-induced hepatic sinusoidal obstructive syndrome.

Lee, Anselm Chi-wai; Goh, Peter Yu-tang

2011-01-01

432

Dielectric breakdown of low-density polyethylene under simulated inverter voltages  

Microsoft Academic Search

Breakdown characteristics have been investigated for low-density polyethylene immersed in silicone oil by applying power-frequency ac voltages with high-frequency components, which are simulated output voltages of a pulse-width-modulation inverter. It was found that the breakdown voltage decreases as the high-frequency component increases. However, the number of zero-crossings of the applied voltage, which is very influential in water-tree growth, does not

H. Suzuki; S. Mukai; Y. Ohki; Y. Nakamichi; K. Ajiki

1997-01-01

433

Zero-Voltage Soft-Switched PWM High-Frequency AC-Link DC-DC Converters Incorporating Saturable Reactor-Assisted Capacitive Lossless Snubber Topology for Distributed Power Supply Systems.  

National Technical Information Service (NTIS)

A new constant frequency soft switching phase shifted mode Pulse Width Modulated (PWM) DC-DC power converter topology suitable for high power applications, which incorporates two phase half bridge high frequency inverter and saturable reactor in series wi...

S. Nagai T. Yamamoto M. Nakaoka S. Hamada

1991-01-01

434

Generalised mc?×?nc-stage switched-capacitor-voltage-multiplier-based boost DC–AC inverter  

Microsoft Academic Search

A closed-loop scheme of a generalised -stage (multistage) switched-capacitor-voltage-multiplier inverter (SCVMI) is proposed by combining a two-phase interleaved phase generator and a sinusoidal-pulse-width-modulation (SPWM) control for low-power boost dc–ac conversion and regulation. In this SCVMI, the power unit contains two parts: SCVM booster (front) and H-bridge (rear). The SCVM booster is composed of two -stage SC cells and two -stage

Yuen-Haw Chang; Ming-Zong Wu

2012-01-01

435

Generalised mc?×?nc-stage switched-capacitor-voltage-multiplier-based boost DC–AC inverter  

Microsoft Academic Search

A closed-loop scheme of a generalised -stage (multistage) switched-capacitor-voltage-multiplier inverter (SCVMI) is proposed by combining a two-phase interleaved phase generator and a sinusoidal-pulse-width-modulation (SPWM) control for low-power boost dc–ac conversion and regulation. In this SCVMI, the power unit contains two parts: SCVM booster (front) and H-bridge (rear). The SCVM booster is composed of two -stage SC cells and two -stage

Yuen-Haw Chang; Ming-Zong Wu

2011-01-01

436

A New Voltage Stability Index Considering Voltage Limits  

Microsoft Academic Search

Recently, concerns over voltage instability phenomena have been increasing, because significant voltage drops are regarded crucial in stable operations. Thus, effective voltage control schemes using voltage stability indices have been brought to attention in a considerable number of studies. The conventional voltage stability indices are mainly based on evaluating voltage stability margins to a critical point. The operator usually determines

Y. Kataoka; M. Watanabe; S. Iwamoto

2006-01-01

437

Selective and localized radiofrequency heating of skin and fat by controlling surface distributions of the applied voltage: analytical study  

NASA Astrophysics Data System (ADS)

At low frequencies (hundreds of kHz to a few MHz), local energy absorption is proportional to the conductivity of tissue and the intensity of the internal electric field. At 1 MHz, the electric conductivity ratio between skin and fat is approximately 10; hence, skin would heat more provided the intensity of the electric field is similar in both tissues. It follows that selective and localized heat deposition is only feasible by varying electric fields locally. In this study, we vary local intensities of the internal electric field in skin, fat and muscle by altering its direction through modifying surface distributions of the applied voltage. In addition, we assess the long-term effects of these variations on tissue thermal transport. To this end, analytical solutions of the electric and bioheat equations were obtained using a regular perturbation method. For voltage distributions given by second- and eight-degree functions, the power absorption in fat is much greater than in skin by the electrode center while the opposite is true by the electrode edge. For a sinusoidal function, the absorption in fat varies laterally from greater to lower than in skin, and then this trend repeats from the center to the edge of the electrode. Consequently, zones of thermal confinement selectively develop in the fat layer. Generalizing these functions by parametrization, it is shown that radiofrequency (RF) heating of layered tissues can be selective and precisely localized by controlling the spatial decay, extent and repetition of the surface distribution of the applied voltage. The clinical relevance of our study is to provide a simple, non-invasive method to spatially control the heat deposition in layered tissues. By knowing and controlling the internal electric field, different therapeutic strategies can be developed and implemented.

Jiménez-Lozano, Joel; Vacas-Jacques, Paulino; Anderson, R. Rox; Franco, Walfre

2012-11-01

438

Boost Rectifier Power Factor Correction Circuits with Improved Harmonic and Load Voltage Regulation Responses  

Microsoft Academic Search

The time domain step response for rapid load changes can be improved in boost type power factor correction circuits by using a capacitor voltage model. In single phase PFC circuits, the dc bus voltage must have a significant voltage ripple at twice the mains frequency due to energy balance requirements. In traditional implementations, the presence of this ripple voltage causes

Peter Wolfs; Peter Thomas

2007-01-01

439

A novel method to achieve zero-voltage regulation in buck converter  

Microsoft Academic Search

The function control law for a buck converter is derived to achieve zero voltage regulation of the output voltage. A new method to retrieve the low frequency component of the inductor voltage is proposed and analyzed. The stability of the closed loop system using a proportional and differential controller is analyzed. The effect of the supply voltage and load current

Yan-Fei Liu; Paresh C. Sen

1995-01-01

440

Electrochemical production of ferrate(VI) using sinusoidal alternating current superimposed on direct current: grey and white cast iron electrodesThis paper is dedicated to the memory of Professor Ivo Roušar  

Microsoft Academic Search

The current yield during the electrochemical production of ferrate(VI) in a batch cell was measured using grey and white cast iron as working electrode materials. Sinusoidal alternating current superimposed on the direct current with a frequency varying in the range 0.1mHz to 5kHz was used. The amplitude (peak to peak) of the alternating current component varied from 39.8 to 91.1mAcm?2

K Bouzek; M Lipovská; M Schmidt; I RoušarDeceased; A. A Wragg

1998-01-01

441

The effects of acceleration on the mechanical impedance response of a primate model exposed to sinusoidal vibration.  

PubMed

Criteria for developing active and passive isolation mechanisms for reducing the effects of whole-body vibration exposure rely on a thorough understanding of the stiffness, damping, and resonance behaviors of the human or human surrogate body. Three Rhesus monkeys were exposed to seated whole-body sinusoidal vibration between 3 and 20 Hz at 0.69 and 3.47 msec-2 rms (0.1 and 0.5 g peak) accelerations. The mechanical impedance magnitude and phase were calculated as the ratio and phase relation between the transmitted force and input velocity, respectively, at the seat. The resultant profiles showed a significant decrease in the primary resonance frequency with increasing acceleration. At the lower acceleration level, a second lower impedance peak was observed at approximately 5 Hz. A three-mass, two degree-of-freedom model, which included upper torso and leg representation, was used to determine the mechanical parameters that best described the measured responses. The mean stiffness coefficients and the mean undamped natural frequencies associated with the upper torso and leg subsystems showed a significant decrease with increases in the acceleration level. The results of this study strongly suggested that nonlinear stiffness properties were responsible for the observed differences in the biodynamic response of the Rhesus monkey with acceleration level. PMID:8060029

Smith, S D; Kazarian, L E

442

Liver sinusoidal endothelial cell lectin inhibits CTL-dependent virus clearance in mouse models of viral hepatitis.  

PubMed

Liver sinusoidal endothelial cell lectin (LSECtin) was recently reported to suppress intrahepatic T cell immunity and to limit immune-mediated liver injury. However, its role in the outcome and pathogenesis of viral infection has not yet been elucidated. Using a mouse model infected with a hepatotropic adenovirus, we found that the absence of LSECtin led to a higher frequency of intrahepatic effector CTLs. These cells produced higher levels of antiviral cytokines and cytotoxic factors and exhibited an increased expression of the transcription factors T-bet and Runx3. This phenotype observed in the LSECtin-knockout cells mediated a more efficient virus-specific cytotoxicity compared with that of wild-type cells. As a consequence, LSECtin deficiency significantly accelerated liver adenovirus clearance. In contrast, LSECtin upregulation in the liver delayed viral clearance; this delayed clearance was accompanied by the downregulation of the antiviral activity of CTLs. We further constructed an immunocompetent mouse model of acute hepatitis B viral infection to demonstrate that LSECtin significantly delayed the clearance of hepatitis B virus from blood and infected hepatocytes by limiting the frequency of hepatitis B virus-specific IFN-?-producing cells. Consistent with this function, LSECtin was upregulated in the liver of mouse models of viral hepatitis. Taken together, our results suggest that LSECtin may facilitate the reduction of liver inflammation at the cost of delaying virus clearance and that this effect might be hijacked by the virus as an escape mechanism. PMID:23487419

Liu, Biao; Wang, Min; Wang, Xiaowen; Zhao, Dianyuan; Liu, Di; Liu, Jing; Chen, Pei-Jer; Yang, Dongliang; He, Fuchu; Tang, Li

2013-03-13

443

Profile-based optimization of power performance by using dynamic voltage scaling on a PC cluster  

Microsoft Academic Search

Currently, several of the high performance processors used in a PC cluster have a DVS (dynamic voltage scaling) architecture that can dynamically scale processor voltage and frequency. Adaptive scheduling of the voltage and frequency enables us to reduce power dissipation without a performance slowdown during communication and memory access. In this paper, we propose a method of profiled-based power-performance optimization

Yoshihiko Hotta; Mitsuhisa Sato; Hideaki Kimura; Satoshi Matsuoka; Taisuke Boku; Daisuke Takahashi

2006-01-01

444

Intensity Distribution from a Sinusoidal Grating and Application to Diffusion Measurements.  

National Technical Information Service (NTIS)

The general vector analysis of Stroke has been applied to the calculation of the intensity distribution among the real diffraction order of a sinusoidal grating at normal incidence. The results are presented for gratings of period 10 and 20 microns and fo...

J. M. Blakely D. L. Olson

1967-01-01

445

Extraction of Peak-to-Peak and RMS Sinusoidal Jitter Using an Analytic Signal Method  

Microsoft Academic Search

This paper proposes a new method based on analytic signal theory for extracting both instantaneous and RMS sinusoidal jitter from PLL output signals. The method relies on the extension of a real signal into an analytic signal by utilizing the Hilbert transform. Both the theoretical basis and fundamental concepts of the proposed method are explained. A review of conventional testing

Takahiro J. Yamaguchi; Masahiro Ishida; Mani Soma; Toshifumi Watanabe; Tadahiro Ohmi

2000-01-01

446

Estimation and analysis of iron losses in induction motors under sinusoidal and PWM excitation  

Microsoft Academic Search

In this paper the iron losses in induction motors are estimated and analysed using time-stepping Finite Element Method (FEM) both with sinusoidal and PWM supply. The iron losses calculation has been carried out by add up the iron losses produced by orthogonal components of the flux density, as if the iron losses produced by these components were independent phenomena. The

Zbigniew Gmyrek; Aldo Boglietti; A. Cavagnino

2008-01-01

447

A Novel Migration Pathway for Rat Dendritic Cells from the Blood: Hepatic Sinusoids-Lymph Translocation  

Microsoft Academic Search

Summary The migration pathways for dendritic cells (DC) from the blood are not yet completely re- solved. In our previous study, a selective recruitment of DC progenitors from the blood to the liver was suggested. To clarify the role of the hepatic sinusoids in the migration of blood DC, relatively immature DC and mature DC were isolated from hepatic and

Shunsuke Kudo; Kenjiro Matsuno; Taichi Ezaki; Michio Ogawa

448

Comparative analysis between active and passive current transducers in sinusoidal and distorted conditions  

Microsoft Academic Search

Current measurements are a critical item in the monitoring of modern electrical power plants, since the quantities to be measured often show high harmonic content. The current transducers should therefore guarantee a good accuracy even when they operate with distorted waveforms. In this paper, the behavior of some devices commonly used for current measurement is examined, considering either sinusoidal or

Nicola Locci; Carlo Muscas

2001-01-01

449

Comparative analysis between active and passive current transducers in sinusoidal and distorted conditions  

Microsoft Academic Search

In this paper the behaviour of some devices commonly used for current measurement is examined by means of a number of experimental tests, considering either sinusoidal or distorted conditions. Traditional current transformers, transducers based on the Hall effect and resistive shunts combined with isolation amplifiers have been considered. The comparison is performed by taking into account amplitude errors and time

N. Locci; C. Muscas

1999-01-01

450

Axial graded silicon carbide fibers with fluctuating carbon layer and sinusoidal electrical resistivity  

Microsoft Academic Search

Axial graded silicon carbide fibers with fluctuating carbon layer and sinusoidal electrical resistivity in the range of 100–102?·cm were prepared. The preparation of these axial graded fibers was simply realized by continuous pyrolysis using an elliptic rotating spool that makes the pyrolysis time of every axial part of the fiber in furnace varies periodically. The period of the electrical resistivity

Tian-jiao Hu; Xiao-dong Li; Yi-he Li; Hao Wang; Jun Wang

2011-01-01

451

Stress Singularities in a Model of a Wood Disk under Sinusoidal Pressure  

Microsoft Academic Search

A thin, solid, circular wood disk, cut from the transverse plane of a tree stem, can be modeled as a cylindrically orthotropic elastic material. It is known that a stress singularity can occur at the center of a cylindrically orthotropic disk subjected to uniform pressure. If a solid cylindrically orthotropic disk is subjected to sinusoidal pressure distributions, then other stress

Jay A. Johnson; John C. Hermanson; Steven M. Cramer

2005-01-01

452

Differential influence of sinusoidal and noisy inputs on synaptic connections in a network with STDP  

Microsoft Academic Search

We hypothesize that the type of cortical network activation influences synaptic connectivity in the network, eventually expressed in an altered responsiveness to external stimuli. Our predictions are based on a time discrete canonical model of spike-time–dependent plasticity. The results show that, at a given synaptic connection strength in the network, sinusoidal input to the network can decrease synaptic potentiation whereas

J. Mayer; H. G. Schuster; H.-V. V. Ngo; M. Mölle; J. Born

2012-01-01

453

A Fixed Dimension Modified Sinusoid Model (FD-MSM) for Single Microphone Sound Separation  

Microsoft Academic Search

The lack of a flexible analysis model has been introduced as an important issue in different applications like source separation. In this paper, a fixed dimension modified sinusoid model (FD-MSM) is proposed for analysis of all audible signals consisting of speech, music and their mixtures. Employing the peak picking in Meldomain gives rise to a fixed number of parameters in

P. M. B. Mahale; A. Sayadiyan; A. B. Tashk

2007-01-01

454

The dynamics of a bouncing ball with a sinusoidally vibrating table revisited  

Microsoft Academic Search

The dynamical behavior of a bouncing ball with a sinusoidally vibrating table is revisited in this paper. Based on the equation of motion of the ball, the mapping for period-1 motion is constructured and thereby allowing the stability and bifurcation conditions to be determined. Comparison with Holmes's solution [1] shows that our range of stable motion is wider, and through

Albert C. J. Luo; Ray P. S. Han

1996-01-01

455

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...

456

Exponential sinusoidal model for predicting temperature inside underground wine cellars from a Spanish region  

Microsoft Academic Search

This article develops a mathematical model for determining the annual cycle of air temperature inside traditional underground wine cellars in the Spanish region of “Ribera del Duero”, known because of the quality of its wines. It modifies the sinusoidal analytical model for soil temperature calculation. Results obtained when contrasting the proposed model with experimental data of three subterranean wine cellars

Fernando R. Mazarron; Ignacio Canas

2008-01-01

457

Hydromagnetic effect on mixed convection in a lid-driven cavity with sinusoidal corrugated bottom surface  

Microsoft Academic Search

The present numerical simulation is conducted to analyze the mixed convection flow and heat transfer in a lid-driven cavity with sinusoidal wavy bottom surface in presence of transverse magnetic field. The enclosure is saturated with electrically conducting fluid. The cavity vertical walls are insulated while the wavy bottom surface is maintained at a uniform temperature higher than the top lid.

Rehena Nasrin; Salma Parvin

2011-01-01

458

Lipopeliosis: fat induced sinusoidal dilatation in transplanted liver mimicking peliosis hepatis  

Microsoft Academic Search

A distinct peliosis-like lesion arose in the liver allograft of a 51 year old man. This lesion was caused by necrotic, fat-laden hepatocytes that released fat globules into the sinusoids. These then became strikingly distended with cysts, thus mimicking peliosis hepatitis. It is suggested that this lesion be called lipopeliosis.

L Ferrell; N Bass; J Roberts; N Ascher

1992-01-01

459

Immunohistochemical patterns of human liver sinusoids under different conditions of pathologic perfusion.  

PubMed

This study reports the effects of altered hepatic perfusion on the sinusoidal bed and the phenotypic characteristics of sinusoidal endothelial cells (SECs). Sinusoids were studied by the application of endothelial cell markers (CD31, CD34, CD105, and ATZ 11) in lesions with localized increased perfusion (liver cell adenoma, focal nodular hyperplasia, and macroregenerative nodule), in chronic congestion, in decreased portovenous inflow (portal vein thrombosis), and in decreased arteriohepatic perfusion (obliterative arteriopathy in chronic allograft rejection). SECs react in a sensitive and uniform way to all investigated conditions of different pathologic liver perfusion: expression of CD31, CD34, and ATZ 11 by SEC is found in inflow areas, CD105-positive SECs are found at the end of the sinusoidal blood stream. This blood flow-orientated phenotypic shift of SECs was accompanied by a perisinusoidal accumulation of activated hepatic stellate cells and collagen IV. These findings are helpful in liver biopsies and provide new insights into the angioarchitecture of benign nodular lesions. PMID:11407479

Theuerkauf, I; Zhou, H; Fischer, H P

2001-05-01

460

Treatment of Sinusoidal Obstruction Syndrome With Defibrotide: A Single-Center Experience  

Microsoft Academic Search

Sinusoidal obstruction syndrome (SOS) is a frequent, troubling, and potentially fatal complication of hematopoietic stem cell transplantation. Despite promising results with defibrotide (DF), no treatment has been established as standard. DF is a single-stranded polydeoxyribonucleotide, obtained from controlled depolymerization of porcine intestinal mucosal cells. It has antithrombotic, antiischemic, antiinflammatory, and thrombolytic properties without significant side effects. We retrospectively evaluated the

G. T. Sucak; Z. S. Aki; Z. N. Ozkurt; R. Haznedar

2007-01-01

461

Review article: updates in the pathogenesis and therapy of hepatic sinusoidal obstruction syndrome.  

PubMed

Hepatic sinusoidal obstruction syndrome is frequently linked to high-dose chemotherapy/total-body irradiation in recipients of haematopoietic stem cell transplantation, long-term use of azathioprine after organ transplantation and other chemotherapeutic agents. The incidence of hepatic sinusoidal obstruction syndrome varies from 0% to 70%, and is decreasing. Disease risk is higher in patients with malignancies, hepatitis C virus infection, those who present late, when norethisterone is used to prevent menstruation, and when broad-spectrum antibiotics and antifungals are used during and after the conditioning therapy. Hepatic sinusoidal obstruction syndrome presents with tender hepatomegaly, hyperbilirubinaemia and ascites, and diagnosis is mainly clinical (Seattle and Baltimore Criteria). Imaging excludes biliary obstruction and malignancy, but cannot establish accurate diagnosis. Hepatic sinusoidal obstruction syndrome may be prevented by avoiding the highest risk regimens, using non-myelo-ablative regimens, and reducing total-body irradiation dose. Treatment is largely symptomatic and supportive, because 70-80% of patients recover spontaneously. Tissue plasminogen activator plus heparin improves outcome in <30% of cases. Defibrotide, a polydeoxyribonucleotide, is showing encouraging results. Transjugular intrahepatic porto-systemic shunt relieves ascites, but does not improve outcome. Liver transplantation may be an option in the absence of malignancy. Prognosis is variable and depends on disease severity, aetiology and associated conditions. Death is most commonly caused by renal or cardiopulmonary failure. PMID:16393276

Helmy, A

2006-01-01

462

Room-temperature multiwavelength erbium-doped fiber ring laser employing sinusoidal phase-modulation feedback  

Microsoft Academic Search

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.

Kejiang Zhou; Dongyun Zhou; Fengzhong Dong; Nam Quoc Ngo

2003-01-01

463

Direct subnanosecond voltage monitors  

SciTech Connect

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.

Barth, J.E.; Sajeant, W.J.

1981-01-01

464

The strength of the reflex response to sinusoidal stretch of monkey jaw closing muscles during voluntary contraction.  

PubMed Central

1. Rhesus monkeys were trained to exert steady biting forces of 3--60 N for 1--2 sec. This behaviour was well maintained while sinusoidal or step opening and closing movements were imposed on the jaw. 2. The amplitude of the force modulation during sinusoidal stretching was divided by the amplitude of movement to obtain the magnitude of stiffness. This estimate was made at frequencies from 2 to 50 Hz at amplitudes of 100 and 500 micrometer (half the peak-to-peak movement at the incisors). 3. Peak magnitudes of stiffness were seen with frequencies of 8--15 Hz when the amplitude of movement was small; there was a great deal of variation between individual animals. This variation was most striking with mean forces of 25--35 N. The stiffness was greatest in animals that showed considerable spontaneous tremor, and the highest levels of stiffness were often recorded with frequencies near which tremor amplitude was large. A marked phase lag in the force response was often seen during small amplitude stretching at 8--30 Hz. 4. Estimates of stiffness for larger amplitude (500 micrometer) stretching showed less variation; the magnitude of stiffness showed maximum values below 10 Hz and a minimum at 15--30 Hz. Force always showed a phase lead on position although this lead became small in the frequency range where with smaller movement there had been phase lags. The magnitude of stiffness increased with increasing mean force. 5. Bilateral electrolytic lesions were made in the brain stems of three animals; they reduced by over 95% the expected number of cells in the mesencephalic nucleus of the fifth cranial nerve on either side. These lesions interrupted the afferent pathway for the stretch reflex and so abolished excitatory electromyogram (e.m.g.) responses to step stretches of the jaw closing muscles. 6. Such reflex responses as persisted after the lesions were small and inhibitory. E.m.g. silences followed both step stretch and release; the response to release was a 'load compensation' that could not be attribu