These are representative sample records from Science.gov related to your search topic.
For comprehensive and current results, perform a real-time search at Science.gov.
1

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

NASA Astrophysics Data System (ADS)

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.; Macheret, Sergey O.

2008-08-01

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

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

Microsoft Academic Search

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

Dmitry F. Opaits; Alexandre V. Likhanskii; Gabriele Neretti; Sohail Zaidi; Mikhail N. Shneider; Richard B. Miles; Sergey O. Macheret

2008-01-01

4

Ion acoustic soliton excitation using a modulated high-frequency sinusoidal wave  

Microsoft Academic Search

Experiments on the excitation of ion acoustic solitons using a fine mesh grid in a normal two component plasma are described. The excitation is novel in that a modulated high-frequency sinusoidal wave voltage signal is applied to the grid. The carrier frequency of the high-frequency sinusoidal wave is above the ion plasma frequency. An interpretation of the velocity modulation and

Seungjun Yi; Er-Wei Bai; Karl E. Lonngren

1997-01-01

5

Self-mixing vibration measurement using emission frequency sinusoidal modulation  

NASA Astrophysics Data System (ADS)

In this paper, a simplified phase demodulation scheme is applied to recover vibration trail on a laser self-mixing interferometer for noncontact vibration measurement. The emission of semiconductor laser diode is modulated by injecting sinusoidal wave, and corresponding interference signal is a quasi-sinusoid wave. The vibration mathematical model for semiconductor laser diode is theoretically educed from basic self-mixing theory, the variation of target is converted into phase information. The simulation of demodulation algorithm and standard deviation are presented and the reconstructed waveform displays a desirable consistence with various moving trails. Following the principle, a minimum experimental system is established and position variation of the target mirror driven by voltage signal is translated into phase shifts, feedback is controlled at weak level during experiment, Fourier transform is implemented to analyze phase information. The comparisons of both amplitude and velocity with a Germany Doppler vibrometer are performed to testify vibration model, the error of proposed demodulation method is less than 30 nm and achieve a high accuracy in vibration frequency. The experimental results indicate the traditional phase technology can be applied on complex optical power signal after adaption providing a feasible application prospects in industrial and scientific situation with an inexpensive semiconductor laser.

Tao, Yufeng; Wang, Ming; Guo, Dongmei; Hao, Hui; Liu, Qiang

2015-04-01

6

Applications of truncated QR methods to sinusoidal frequency estimation  

NASA Technical Reports Server (NTRS)

Three truncated QR methods are proposed for sinusoidal frequency estimation: (1) truncated QR without column pivoting (TQR), (2) truncated QR with preordered columns, and (3) truncated QR with column pivoting. It is demonstrated that the benefit of truncated SVD for high frequency resolution is achievable under the truncated QR approach with much lower computational cost. Other attractive features of the proposed methods include the ease of updating, which is difficult for the SVD method, and numerical stability. TQR methods thus offer efficient ways to identify sinusoidals closely clustered in frequencies under stationary and nonstationary conditions.

Hsieh, S. F.; Liu, K. J. R.; Yao, K.

1990-01-01

7

Frequency to Voltage Converter Analog Front-End Prototype  

NASA Technical Reports Server (NTRS)

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

Mata, Carlos; Raines, Matthew

2012-01-01

8

Multilevel-Dc-Bus Inverter For Providing Sinusoidal And Pwm Electrical Machine Voltages  

DOEpatents

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 respective one of the commutation switches, a plurality of dc source connections providing a multi-level dc bus for the full bridge network of commutation switches to produce sinusoidal voltages or PWM signals, and a controller connected for control of said dc source connections and said full bridge network of commutation switches to output substantially sinusoidal voltages to the stator windings. With the invention, the number of semiconductor switches is reduced to m+3 for a multi-level dc bus having m levels. A method of machine control is also disclosed.

Su, Gui-Jia [Knoxville, TN

2005-11-29

9

Physiologic bladder evacuation with selective sacral root stimulation: sinusoidal signal and organ-specific frequency.  

PubMed

In patients with spinal cord injury above S2, who characteristically have both detrusor hyperflexia and sphincteric spasm, sacral anterior root stimulation can evacuate the bladder, but sacral deafferentation is needed to eliminate the hyperreflexia for normal bladder filling. The common stimulation parameters for these patients activate the detrusor and the external urethral sphincter simultaneously (detrusor-sphincter dyssynergia), and the resultant post-stimulus voiding is not physiologic. We sought to determine organ-specific stimulation parameters. In 20 male dogs, the rectangular pulse and sinusoidal signal forms were evaluated with a variety of parameters for stimulation of S2 and S3 anterior roots extra- and intradurally (i.e., stimulation frequency and voltage, uni- versus bilateral electrode placement, and degree of bladder filling). New torpedo-shaped bipolar electrodes were used, adjusted to neural diameter. The best results were recorded with intradural bilateral sinusoidal signal. Sphincteric fatigue was produced by pre-stimulating S2 with 104+/-17 Hz and 0.8+/-0.1 V for 10 to 15 seconds before S3 stimulation. S3 stimulation with 16+/- 2.1 Hz and 0.4+/-0.1 V evoked a detrusor pressure of 28.7+/-3.0 cm H2O above the sphincteric pressure. Selective anterior root stimulation with organ-specific stimulation parameters can effect initial sphincteric fatigue to achieve physiologic voiding. PMID:11835428

Sievert, Karl-Dietrich; Gleason, Curtis A; Jünemann, Klaus-Peter; Alken, Peter; Tanagho, Emil A

2002-01-01

10

Multidimensional Sinusoidal Frequency Estimation Using Subspace and Projection  

E-print Network

in this dimension, a set of projection separation matrices is then constructed to separate all frequencies, has received extensive attention for its widespread applications in numerous fields such as MIMO magnetic resonance spectroscopy [4]. Many high-resolution subspace-based parameter estimation techniques

So, Hing-Cheung

11

Statistical analysis of MUSIC and subspace rotation estimates of sinusoidal frequencies  

Microsoft Academic Search

Consideration is given to the analysis of the large-sample second-order properties of multiple signal classification (MUSIC) and subspace rotation (SUR) methods, such as ESPRIT, for sinusoidal frequency estimation. Explicit expressions for the covariance elements of the estimation errors associated with either method are derived. These expressions of covariances are then used to analyze and compare the statistical performances of the

Petre Stoica; Torsten Soderstrom

1991-01-01

12

Effect of modulator asynchrony of sinusoidal and noise modulators on frequency and amplitude modulation detection interference.  

PubMed

The effect on modulation detection interference (MDI) of timing of gating of the modulation of target and interferer, with synchronously gated carriers, was investigated in three experiments. In a two-interval, two-alternative forced choice adaptive procedure, listeners had to detect 15 Hz sinusoidal amplitude modulation (AM) or frequency modulation (FM) imposed for 200 ms in the temporal center of a 600 ms target sinusoidal carrier. In the first experiment, 15 Hz sinusoidal FM was imposed in phase on both target and interferer carriers. Thresholds were lower for nonoverlapping than for synchronous modulation of target and interferer, but MDI still occurred for the former. Thresholds were significantly higher when the modulators were gated synchronously than when the interferer modulator was gated on before and off after that of the target. This contrasts with the findings of Oxenham and Dau [J. Acoust. Soc. Am. 110, 402-408 (2001)], who reported no effect of modulation asynchrony on AM detection thresholds, using a narrowband noise modulator. Using FM, experiment 2 showed that for temporally overlapping modulation of target and interferer, modulator asynchrony had no significant effect when the interferer was modulated by a narrowband noise. Experiment 3 showed that, for AM, synchronous gating of modulation of the target and interferer produced lower thresholds than asynchronous gating, especially for sinusoidal modulation of the interferer. Results are discussed in terms of specific cues available for periodic modulation, and differences between perceptual grouping on the basis of common AM and FM. PMID:12509019

Gockel, Hedwig; Carlyon, Robert P; Deeks, John M

2002-12-01

13

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

PubMed

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

Fisher, Karen M; Jillani, Ngalla E; Oluoch, George O; Baker, Stuart N

2015-03-01

14

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

PubMed Central

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

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

2014-01-01

15

A Sinusoidal Current Driver With an Extended Frequency Range and Multifrequency Operation for Bioimpedance Applications.  

PubMed

This paper describes an alternative sinusoidal current driver suitable for bioimpedance applications where high frequency operation is required. The circuit is based on a transconductor and provides current outputs with low phase error for frequencies around its pole frequency. This extends the upper frequency operational limit of the current driver. Multifrequency currents can be generated where each individual frequency is phase corrected. Analysis of the circuit is presented together with simulation and experimental results which demonstrate the proof of concept for both single and dual frequency current drivers. Measurements on a discrete test version of the circuit demonstrate a phase reduction from 25 (°) to 4 (°) at 3 MHz for 2 mAp-p output current. The output impedance of the current driver is essentially constant at about 1.1 M ? over a frequency range of 100 kHz to 5 MHz due to the introduction of the phase compensation. The compensation provides a bandwidth increase of a factor of about six for a residual phase delay of 4 (°) . PMID:25148669

Langlois, Peter J; Neshatvar, Nazanin; Demosthenous, Andreas

2014-08-19

16

Influence of sinusoidally modulated visual stimuli at extremely low frequency range on the human EEG activity.  

PubMed

The purpose of this study was to investigate whether sinusoidally modulated visual stimuli at extremely low frequencies (ELF) of 50, 16.66, 13, 10, 8.33 and 4Hz could influence the changes in EEG activity in 33 human subjects. An improved design of visual stimulator system has addressed an issue of electrical interference from electrical signals driven by LED arrays onto simultaneously recorded EEG. A comparison between 1 and 3-Way ANOVA was performed in order to evaluate whether visual stimuli at ELFs could influence the EEG in humans to compliment the currently active medical research in seasonal affective disorder (SAD) and photic driving. The results revealed that under evaluation of 1 and 3-Way repeated-measures ANOVA tests, the Theta, Alpha2 and Gamma EEG bands exhibited a common significant difference between ELF visual stimuli. PMID:17945633

Cvetkovic, D; Simpson, D; Cosic, I

2006-01-01

17

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

18

Broadband linear high-voltage amplifier for radio frequency ion traps.  

PubMed

We developed a linear high-voltage amplifier for small capacitive loads consisting of a high-voltage power supply and a transistor amplifier. With this cost-effective circuit including only standard parts sinusoidal signals with a few volts can be amplified to 1.7 kVpp over a usable frequency range at large-signal response spanning four orders of magnitude from 20 Hz to 100 kHz under a load of 10 pF. For smaller output voltages the maximum frequency shifts up to megahertz. We test different capacitive loads to probe the influence on the performance. The presented amplifier is sustained short-circuit proof on the output side, which is a significant advantage over other amplifier concepts. The amplifier can be used to drive radio frequency ion traps for single charged nano- and microparticles, which will be presented in brief. PMID:25430133

Kuhlicke, Alexander; Palis, Klaus; Benson, Oliver

2014-11-01

19

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

20

46 CFR 111.01-17 - Voltage and frequency variations.  

Code of Federal Regulations, 2014 CFR

...Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ELECTRICAL ENGINEERING ELECTRIC SYSTEMS-GENERAL REQUIREMENTS General § 111.01-17 Voltage and frequency variations. Unless otherwise stated,...

2014-10-01

21

46 CFR 111.01-17 - Voltage and frequency variations.  

Code of Federal Regulations, 2010 CFR

...Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ELECTRICAL ENGINEERING ELECTRIC SYSTEMS-GENERAL REQUIREMENTS General § 111.01-17 Voltage and frequency variations. Unless otherwise stated,...

2010-10-01

22

46 CFR 111.01-17 - Voltage and frequency variations.  

Code of Federal Regulations, 2011 CFR

...Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ELECTRICAL ENGINEERING ELECTRIC SYSTEMS-GENERAL REQUIREMENTS General § 111.01-17 Voltage and frequency variations. Unless otherwise stated,...

2011-10-01

23

46 CFR 111.01-17 - Voltage and frequency variations.  

Code of Federal Regulations, 2013 CFR

...Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ELECTRICAL ENGINEERING ELECTRIC SYSTEMS-GENERAL REQUIREMENTS General § 111.01-17 Voltage and frequency variations. Unless otherwise stated,...

2013-10-01

24

46 CFR 111.01-17 - Voltage and frequency variations.  

Code of Federal Regulations, 2012 CFR

...Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ELECTRICAL ENGINEERING ELECTRIC SYSTEMS-GENERAL REQUIREMENTS General § 111.01-17 Voltage and frequency variations. Unless otherwise stated,...

2012-10-01

25

Process and User Driven Dynamic Voltage and Frequency Scaling  

Microsoft Academic Search

We propose and evaluate two new and independently-applicable techniques, process- driven voltage scaling (PDVS) and user-driven frequency scaling (UDFS), for improved power management on processors that support Dynamic Voltage and Frequency Scaling (DVFS), e.g, those used in current laptop and desktop computers. In PDVS, a CPU- customized profile is derived offline that encodes the minimum voltage needed to achieve stability

Arindam Mallik; Bin Lin; Peter Dinda; Gokhan Memik; Robert Dick

26

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

27

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

28

Improving battery charging performance by using sinusoidal current charging with the minimum AC impedance frequency  

Microsoft Academic Search

This paper aims to explore the optimal charging frequency of the LiFePO4 battery by the analysis of the AC impedance. The experiments show that the optimal charging frequency is at the minimum AC impedance frequency fZmin. In such a condition, the LiFePO4 battery charging time and charging efficiency are improved about 5.6% and 6.8%, respectively. In addition, the increased temperature

Liang-Rui Chen; Shing-Lih Wu; Tsair-Rong Chen

2010-01-01

29

Enhanced coding of high-frequency tonal components in MPEG-D USAC through joint application of ESBR and sinusoidal modeling  

Microsoft Academic Search

The new eSBR tool of MPEG-D Universal Speech and Audio Coding offers a great advantage in compression of high frequency content, however it produces audible artifacts for sounds whose pitch frequencies are strongly variable or exceeding the split frequency of eSBR. We propose an extension of the forthcoming standard by adding a high frequency sinusoidal tool. This tool introduces additional

Tomasz Zernicki; Maciej Bartkowiak; Marek Domanski

2011-01-01

30

High frequency, high voltage MOSFET isolation amplifier  

Microsoft Academic Search

The present invention utilizes a high voltage isolation amplifier as the drive means for the inductor of a programmable microwave attenuator. A pair of power MOSFET devices are used to control the current flow through a magnetic yoke. The power MOSPET devices cooperate with floating operational amplifier drive circuits to act as a transconductance amplifiers and pass a load current

1986-01-01

31

High frequency AC power converter for low voltage circuits  

E-print Network

This thesis presents a novel AC power delivery architecture that is suitable for VHF frequency (50-100MHz) polyphase AC/DC power conversion in low voltage integrated circuits. A complete AC power delivery architecture was ...

Salazar, Nathaniel Jay Tobias

2012-01-01

32

User and process-driven dynamic voltage and frequency scaling  

Microsoft Academic Search

We describe and evaluate two new, independently-applicabl e power reduction techniques for power management on proces- sors that support dynamic voltage and frequency scaling (DV FS): user-driven frequency scaling (UDFS) and process-driven v olt- age scaling (PDVS). In PDVS, a CPU-customized profile is de- rived offline that encodes the minimum voltage needed to achi eve stability at each combination of

Bin Lin; Arindam Mallik; Peter A. Dinda; Gokhan Memik; Robert P. Dick

2009-01-01

33

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...

34

Induced voltage test of distribution transformers using static frequency inverters  

Microsoft Academic Search

In high voltage systems, conventional method of generating a wave with a frequency over 50 Hz that has high power is interconnecting a motor and a generator with nominal frequency over 50 Hz, like 100 Hz or 150 Hz; but for routine test of distribution transformers, it is not economical to construct a experimental setup with a motor and generator.

H. Mohseni; A. Shaygani Akmal; J. Jadidian; E. Hashemi; E. Agheb; A. Naieny; A. Ghorbandaeipour; K. Niayesh

2008-01-01

35

MEMS FILTER WITH VOLTAGE TUNABLE CENTER FREQUENCY AND BANDWIDTH  

E-print Network

This paper reports on the design of a reconfigurable ladder filter using RF MEMS resonators with voltage-tunable series and parallel resonance frequencies. The ladder filter consists of one shunt and two series enables channel agility and reconfigurability, substantially reducing the filter count in channel- select

Afshari, Ehsan

36

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.

37

Conventional-band and long-wavelength-band efficient wavelength conversion by difference-frequency generation in sinusoidally chirped optical superlattice waveguides  

NASA Astrophysics Data System (ADS)

We report difference-frequency generation (DFG)-based wavelength conversion with sinusoidally chirped optical superlattices (SCOSs) in lithium niobate waveguides. The SCOS shows much broader bandwidth, larger pump-wavelength tolerance and flatter response with some conversion efficiency penalty than the periodic grating with the same length. Especially, the conversion bandwidth of the SCOS is over the whole conventional band and long-wavelength band, which is very helpful to broadband optical communications. The main advantages of the DFG-based wavelength conversion with SCOS structures over the cascaded second-order effect-based wavelength conversion are higher conversion efficiency, broader bandwidth, better pump-wavelength tolerance and response flatness when the device is shorter. In order to ensure the conversion quality, analysis shows that the manufacture tolerance of the SCOS period should not more than 0.02 ?m.

Gao, Shiming; Yang, Changxi; Jin, Guofan

2004-09-01

38

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

39

Automatic frequency control of voltage-controlled oscillators  

NASA Technical Reports Server (NTRS)

Optical-capacitive coupling is used for isolation of control voltages, such as the high-voltage level of a klystron control electrode that is not referenced to ground, to serve as error voltages referenced to system ground so that the magnitude and sense of correction may be transferred.

Kolbly, R. B.

1969-01-01

40

Linear Characteristics of a Metal–Insulator Transition Voltage and Oscillation Frequency in Devices  

Microsoft Academic Search

In order to apply a VO2 metal-insulator transition (MIT) device to a temperature sensor with temperature and voltage, we measure the linear characteristic of the MIT voltage for a VO2-based device when a pulse voltage of 10 ?s is applied to the device to reduce Joule heat. Moreover, the MIT oscillation frequency and the infrared-induced MIT voltage also are linear

Bong-Jun Kim; Giwan Seo; Yong Wook Lee; Sungyoul Choi; Hyun-Tak Kim

2010-01-01

41

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

E-print Network

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

Qiu, Qinru

42

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

E-print Network

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

Lemmon, Michael

43

Voltage and frequency control of SG based wind farms with uncontrolled HVDC rectifier  

Microsoft Academic Search

The present paper introduces the study and validation of a voltage and frequency control technique of Synchronous Generator based off-shore wind farms connected with a line commutated HVDC link with an uncontrolled rectifier. The proposed control technique is based on the use of standard practice current control for the wind turbines and outer, slower loops for voltage and frequency control.

R. Blasco-Gimenez; S. Año?-Villalba; J. Rodri?guez-D'derle?e; F. Morant; S. Bernal

2010-01-01

44

Parallel Dynamic Voltage and Frequency Scaling for Stream Decoding using a Multicore Embedded System  

E-print Network

Scaling (DVFS) is a viable solution: it dynamically adjusts the system voltage or frequency during low slack and data loss with estimation error. We then combine parallel processing and buffer management for adjusting both the system voltage and frequency according to parameters received from the two mechanisms

Trajkovic, Ljiljana

45

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

Microsoft Academic Search

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

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

2003-01-01

46

All Silicon Marx-bank Topology for High-voltage, High-frequency Rectangular Pulses  

Microsoft Academic Search

This paper discusses the operation of a fully integrated solid-state Marx generator circuit, which has been developed for high-frequency (kHz), high-voltage (kV) applications needing rectangular pulses. The conventional Marx generator, used for high-voltage pulsed applications, uses inductors, or resistors, to supply the charging capacitors voltage, which has the disadvantages of size, power loss and frequency limitation. The proposed circuit takes

L. M. Redondo; J. F. Silva; P. Tavares; E. Margato

2005-01-01

47

Sinusoidal transform coding  

NASA Technical Reports Server (NTRS)

It has been shown that an analysis/synthesis system based on a sinusoidal representation of speech leads to synthetic speech that is essentially perceptually indistinguishable from the original. Strategies for coding the amplitudes, frequencies and phases of the sine waves have been developed that have led to a multirate coder operating at rates from 2400 to 9600 bps. The encoded speech is highly intelligible at all rates with a uniformly improving quality as the data rate is increased. A real-time fixed-point implementation has been developed using two ADSP2100 DSP chips. The methods used for coding and quantizing the sine-wave parameters for operation at the various frame rates are described.

Mcaulay, Robert J.; Quatieri, Thomas F.

1988-01-01

48

High frequency link DC-AC converter for UPS with a new voltage clamper  

Microsoft Academic Search

A power conversion system for a UPS (uninterruptible power supply) using a high-frequency link is described. The proposed UPS consists of a high-frequency inverter, a high-frequency transformer, and a cycloconverter with a new voltage clamper. The clamper effectively reduces the power loss of the conversion system. The voltage clamper gave an improved DC-AC conversion efficiency of about 10% more than

Ikuo Yamato; Norikazu Tokunaga; Y. Matsuda; Yutaka Suzuki; H. Amaro

1990-01-01

49

Very-high-frequency low-voltage power delivery  

E-print Network

Power conversion for the myriad low-voltage electronic circuits in use today, including portable electronic devices, digital electronics, sensors and communication circuits, is becoming increasingly challenging due to the ...

Li, Wei, Ph. D. Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science

2013-01-01

50

Digital light-to-frequency converter with preset voltage  

Microsoft Academic Search

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

1983-01-01

51

[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

52

Resonant circuit model and design for a high frequency high voltage switched-mode power supply  

Microsoft Academic Search

This paper presents a practical procedure for the determination of high voltage high frequency transformer parameters. Besides, the paper also presents the design of a resonant circuit for the high voltage switched-mode power supply. The non-idealities of the transformers are part of the resonant circuit, were the leakage inductance and winding capacitances of the transformers are associated with the external

Gleyson L. Piazza; Ricardo L. Alves; Ivo Barbi

2009-01-01

53

A voltage-independent active load for frequency control in microgrids with renewable energy sources  

Microsoft Academic Search

This paper presents a voltage-independent control method for an active load (AL), which is designed for integration in microgrids with the main purpose of frequency control. Ideally, the AL should behave like a controllable linear current sink whose active power is independent of the input voltage. The proposed AL approaches the aforementioned conditions by combining a robust hardware structure with

I. Serban; C. Marinescu; C. P. Ion

2011-01-01

54

CompilerDirected Dynamic Voltage/Frequency Scheduling for Energy Reduction in Microprocessors #  

E-print Network

#­line algorithms [23, 6, 5, 10, 16]. The basic idea is to recognize and eliminate CPU slacks. 1.2 Why of dynamic voltage/frequency adjustment can be significant, global program analyses are needed to detect

Kremer, Ulrich

55

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

56

Zero-voltage switching in high frequency power converters using pulse width modulation  

Microsoft Academic Search

A zero-voltage switching technique is described that utilizes a resonant transition during a short but finite switching interval. This zero-voltage resonant-transition (ZVRT) switching technique can be applied to conventional buck, boost, and buck-boost power converter topologies that operate with a constant switching frequency and use pulsewidth modulation for output control. Since frequency-dependent losses are greatly reduced in the power transistors,

C. P. Henze; H. C. Martin; D. W. Parsley

1988-01-01

57

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

PubMed

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

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

2015-04-01

58

Theory study on a photonic-assisted radio frequency phase shifter with direct current voltage control  

NASA Astrophysics Data System (ADS)

A photonic-assisted radio frequency phase shifter with direct current voltage control is proposed using a polymer-based integrated Mach—Zehnder modulator. A closed-form expression of radio frequency (RF) signal power and phase is given. Theoretical calculation reveals that by carefully setting the bias voltages, RF signal power variation lower than 1-dB and phase accuracy less than 3° can be achieved and are not degraded by perturbation of modulation index once the bias voltage drift is kept within ?3% ~ 3%.

Li, Jing; Ning, Ti-Gang; Pei, Li; Jian, Wei; You, Hai-Dong; Wen, Xiao-Dong; Chen, Hong-Yao; Zhang, Chan; Zheng, Jing-Jing

2014-10-01

59

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

60

Low-frequency switching voltage regulators for terrestrial photovoltaic systems  

NASA Technical Reports Server (NTRS)

The photovoltaic technology project and the stand alone applications project are discussed. Two types of low frequency switching type regulators were investigated. The design, operating characteristics and field application of these regulators is described. The regulators are small in size, low in cost, very low in power dissipation, reliable and allow considerable flexibility in system design.

Delombard, R.

1984-01-01

61

Parameter Estimation of Noise Corrupted Sinusoids  

E-print Network

Existing algorithms for fitting the parameters of a sinusoid to noisy discrete time observations are not always successful due to initial value sensitivity and other issues. This paper demonstrates the techniques of FIR filtering, Fast Fourier Transform, circular autocorreltion, and nonlinear least squares minimization as useful in the parameter estimation of amplitude, frequency and phase exemplified for a low-frequency time-delayed sinusoid describing simple harmonic motion. Alternative means are described for estimating frequency and phase angle. An autocorrelation function for harmonic motion is also derived.

Francis J. O'Brien, Jr.; Nathan Johnnie

2011-05-02

62

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

63

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

SciTech Connect

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

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

2014-08-18

64

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

PubMed Central

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

Hou, Yubin; Lu, Qingyou

2014-01-01

65

Particle Trajectory in Single Phase SF6\\/N2 Bus Duct for Power Frequency Voltage  

Microsoft Academic Search

Diluted SF6\\/N2 mixtures could be a substitute to pure SF6 as insulating medium for high voltage gas insulated systems. They promise to have a lower environmental impact than a system insulated with pure SF6 for the same rating. In this paper particle trajectories are obtained in single phase bus duct for power frequency voltage with SF6\\/N2 gas mixture as insulating

Poonam Upadhyay; J. Amernath; B. P. Singh; Pravin Upadhyay

2006-01-01

66

A UPS With 110-V\\/220-V Input Voltage and High-Frequency Transformer Isolation  

Microsoft Academic Search

This paper proposes an isolated double-conversion uninterruptible power system with power factor correction using a high-frequency transformer and with input voltages equal to 110 V\\/220 V. The arrangement is suitable to rack-type structures because it has a small size and a reduced weight. For both input voltages, the proposed converter has almost the same efficiency processing the same output power.

RenÉ P. Torrico-Bascope; Carlos G. C. Branco; Fernando L. M. Antunes

2008-01-01

67

Improved frequency/voltage converters for fast quartz crystal microbalance applications  

SciTech Connect

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 accurately both in magnitude and phase. Phase-locked loop techniques can be used for obtaining a high performance frequency/voltage converter which can provide reliable measurements. Sensitivity higher than 10 mV/Hz, for a frequency shift resolution of 0.1 Hz, with very low distortion in tracking both the magnitude and phase of the frequency variations around the resonance frequency of the sensor are required specifications. Moreover, the resonance frequency can vary in a broad frequency range from 5 to 10 MHz in typical QCM sensors, which introduces an additional difficulty. A new frequency-voltage conversion system based on a double tuning analog-digital phase-locked loop is proposed. The reported electronic characterization and experimental results obtained with conducting polymers prove its reliability for ac-electrogravimetry measurements and, in general, for fast QCM applications.

Torres, R.; Kim, L. To Thi [GIBEC-Escuela de Ingenieria de Antioquia, Universidad CES, Calle 25, Sur No. 42-73, Envigado (Colombia); Garcia, J. V.; Arnau, A. [Departamento Ingenieria Electronica. ETSI de Telecomunicacion, Universidad Politecnica de Valencia, Camino de Vera s/n, Valencia 46022 (Spain); Perrot, H.; Gabrielli, C. [Universite Pierre et Marie Curie-Paris 6, Laboratoire Interfaces et Systemes Electrochemiques, CNRS, UPR15-LISE, 4 place Jussieu, Paris 75252 (France)

2008-04-15

68

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

NASA Technical Reports Server (NTRS)

The current and voltage waveshapes associated with the power transitor and the power diode in an example current-or-voltage step-up (buck-boost) converter were analyzed to highlight the problems and possible tradeoffs involved in the design of high voltage high power converters operating at switching frequencies in the range of 100 Khz. Although the fast switching speeds of currently available power diodes and transistors permit converter operation at high switching frequencies, the resulting time rates of changes of current coupled with parasitic inductances in series with the semiconductor switches, produce large repetitive voltage transients across the semiconductor switches, potentially far in excess of the device voltage ratings. The need is established for semiconductor switch protection circuitry to control the peak voltages appearing across the semiconductor switches, as well as to provide the waveshaping action require for a given semiconductor device. The possible tradeoffs, as well as the factors affecting the tradeoffs that must be considered in order to maximize the efficiency of the converters are enumerated.

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

1981-01-01

69

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.

2004-07-21

70

A novel frequency compensation technique for low-voltage low-dropout regulator  

Microsoft Academic Search

A novel frequency compensation technique for low-voltage low-dropout regulator (LDR) is presented. The proposed technique, called pole-control frequency compensation (PCFC), provides faster loop response and does not require a large filtering capacitor. Both theoretical analysis and simulation show that the stability of the LDR using PCFC is independent of the load current, temperature and equivalent series resistance of the filtering

Ka Nang Leung; Philip K. T. Mok; Wing-hung Ki

1999-01-01

71

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

NASA Astrophysics Data System (ADS)

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

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

72

Low-frequency voltage mode sensing of magnetoelectric sensor in package  

E-print Network

Low-frequency voltage mode sensing of magnetoelectric sensor in package F. Li, F. Zhao, Q.M. Zhang with an active biasing circuit and a Metglas/Polyvinylidene fluoride (PVDF)-based magnetoelectric (ME) unimorph for bio-imaging applications. Introduction: The magnetoelectric (ME) effect [1] is defined

Yener, Aylin

73

Static current-voltage characteristics for radio-frequency induction discharge  

SciTech Connect

The aim of this work was to obtain experimentally such characteristic of Radio-Frequency Induction Discharge (RFID) that can play the role of its current-voltage characteristic (CVC) and to explain the nature of current and voltage jumps arising in RF coils at exciting of discharge. Experiments were made in quartz 5.5, 11, 20 cm diam tubes with outer RF coil at pressures 10--100 mTorr, at frequency 13.56 MHz and discharge power to 500 W. In case of outer coil as analogue of discharge voltage it`s convenient to use the value of the RF voltage U{sub R}, induced around outer perimeter of discharge tube. It is evident that current and voltage jumps arising at exciting of discharge are due to low output resistance of standard generators and negative slope of initial part of CVC. Three sets of such dependencies for different pressures were obtained for each diameter of tubes. The influence of different metal electrodes placed into discharge volume on CVC`s shape has been studied also. Experimental results can explain the behavior of HFI discharge as a load of RF generator and give data for calculation of RF circuit.

Budyansky, A.; Zykov, A. [Kharkov Univ. (Ukraine). Scientific Center of Physical Technologies

1995-12-31

74

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

75

Nonholonomic motion planning: steering using sinusoids  

Microsoft Academic Search

Methods for steering systems with nonholonomic c·onstraints between arbitrary configurations are investigated. Suboptimal trajectories are derived for systems that are not in canonical form. Systems in which it takes more than one level of bracketing to achieve controllability are considered. The trajectories use sinusoids at integrally related frequencies to achieve motion at a given bracketing level. A class of systems

Richard M. Murray; S. Shankar Sastry

1993-01-01

76

LM231A/LM231/LM331A/LM331 Precision Voltage-to-Frequency Converters  

E-print Network

be easily channeled through a simple photoisolator to provide isolation against high common mode levels-to-frequency conversion. And the output are capable of driving 3 TTL loads, or a high voltage output up to 40V, yetLM231A/LM231/LM331A/LM331 Precision Voltage-to-Frequency Converters General Description The LM231

Lanterman, Aaron

77

Low noise frequency synthesizer with self-calibrated voltage controlled oscillator and accurate AFC algorithm  

NASA Astrophysics Data System (ADS)

A low noise phase locked loop (PLL) frequency synthesizer implemented in 65 nm CMOS technology is introduced. A VCO noise reduction method suited for short channel design is proposed to minimize PLL output phase noise. A self-calibrated voltage controlled oscillator is proposed in cooperation with the automatic frequency calibration circuit, whose accurate binary search algorithm helps reduce the VCO tuning curve coverage, which reduces the VCO noise contribution at PLL output phase noise. A low noise, charge pump is also introduced to extend the tuning voltage range of the proposed VCO, which further reduces its phase noise contribution. The frequency synthesizer generates 9.75–11.5 GHz high frequency wide band local oscillator (LO) carriers. Tested 11.5 GHz LO bears a phase noise of?104 dBc/Hz at 1 MHz frequency offset. The total power dissipation of the proposed frequency synthesizer is 48 mW. The area of the proposed frequency synthesizer is 0.3 mm2, including bias circuits and buffers.

Peng, Qin; Jinbo, Li; Jian, Kang; Xiaoyong, Li; Jianjun, Zhou

2014-09-01

78

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

79

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

SciTech Connect

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

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

2006-06-19

80

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

81

A novel approach to high voltage substation surveillance using radio frequency interference measurement  

Microsoft Academic Search

The deployment of radio frequency interference (RFI) measurement has gained increasing acceptance as a front line, non-invasive technique to assess the condition of individual high-voltage (HV) electrical equipment items as part of a substation surveillance program. However, successful detection and discrimination of low-repetition rate discharges that typically accompany electrical deterioration is constrained by the capabilities and limitations of the field

A. Nesbitt; B. G. Stewart; S. G. McMeekin; S. Conner; J. C. Gamio; K. Liebech-Lien; H. O. Kristiansen; S. Krakenes

2009-01-01

82

Energy-Efficient Processor Design Using Multiple Clock Domains with Dynamic Voltage and Frequency Scaling  

Microsoft Academic Search

As clock frequency increases and feature size decreases, clock distribution and wire delays present a growing chal- lenge to the designers of singly-clocked, globally syn- chronous systems. We describe an alternative approach, which we call aMultiple Clock Domain (MCD) processor, in which the chip is divided into several (coarse-grained) clock domains, within which independent voltage and fre- quency scaling can

Greg Semeraro; Grigorios Magklis; Rajeev Balasubramonian; David H. Albonesi; Sandhya Dwarkadas; Michael L. Scott

2002-01-01

83

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

84

Plasma characteristics in non-sinusoidally excited CCP discharges  

NASA Astrophysics Data System (ADS)

Using particle-in-cell (PIC) simulations we perform a characterization of the plasma response to positive pulse-type voltage excitations (with a repetition frequency of 13.56 MHz) in a geometrically symmetric CCP reactor (with a gap length of 2 cm) operated with argon (for pressures between 20-500 mTorr). Use of these non-sinusoidal waveforms generates an electrical asymmetry effect in the system, which necessitates the formation of a DC bias. This DC bias, together with the shape of the voltage waveforms used, produces a number of new phenomena that are not present in typical sinusoidal discharges: (1) the plasma density and ion flux can be increased as the pulse width is reduced, (2) a significant asymmetry in the ion fluxes to the powered and grounded electrodes develops as the pressure increases, (3) the average ion energy striking the grounded electrode remains low and approximately constant as the pulse width decreases, and (4) the sheath at the grounded electrode never fully collapses; electrons are no longer lost in sharp pulses, but escape essentially throughout the rf cycle. Effects (1) and (3) above offer the possibility for a new form of control in these types of discharges, where the ion flux can be increased while the ion energy on the grounded electrode can be kept small and essentially constant. This effect has recently been exploited to control the crystallinity of silicon thin films [1], where the low ion bombarding energy was found to improve the quality of films grown. [4pt] [1] Johnson E V, Pouliquen S, Delattre P A, and Booth J P, J. Non-Cryst. Solids 2012, in press.

Lafleur, Trevor; Booth, Jean-Paul

2012-10-01

85

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

86

High voltage-power frequency electrical heating in-situ conversion technology of oil shale  

NASA Astrophysics Data System (ADS)

With the depletion of conventional energy sources,oil shale has got much attention as a new type of energy resource,which is rich and widespread in the world.The conventional utilization of oil shale is mainly focused on resorting to produce shale oil and fuel gas with low extraction efficiency about one in a million due to many shortcomings and limitations.And the in-situ conversion of oil shale,more environmentally friendly,is still in the experimental stage.High voltage-power frequency electrical heating in-situ conversion of oil shale is a new type of in-situ pyrolysis technology.The main equipment includes a high voltage-power frequency generator and interior reactor. The high voltage-power frequency generator can provide a voltage between 220-8000 V which can be adjusted in real time according to the actual situation.Firstly,high voltage is used to breakdown the oil shale to form a dendritic crack between two electrodes providing a conductive channel inside the oil shale rock.And then the power frequency(220V) is used to generate the electric current for heating the internal surface of conductive channel,so that the energy can be transmitted to the surrounding oil shale.When the temperature reaches 350 degree,the oil shale begins to pyrolysis.In addition,the temperature in the conductive channel can be extremely high with high voltage,which makes the internal surface of conductive channel graphitization and improves its heat conduction performance.This technology can successfully make the oil shale pyrolysis, based on a lot of lab experiments,and also produce the combustible shale oil and fuel gas.Compared to other in-situ conversion technology,this method has the following advantages: high speed of heating oil shale,the equipment underground is simple,and easy to operate;it can proceed without the limitation of shale thickness, and can be used especially in the thin oil shale reservoir;the heating channel is parallel to the oil shale layers,which has more effective area for heating and heat transmitting;it has very good adaptability to the formation,the location and depth of the electrodes which can be adjusted according to the specific stratigraphic depth case;A positive(negative) electrode can be connected to multiple negative(positive) electrodes,and the arrangement of the positive and negative electrodes can be evaluated for improving the extraction efficiency.High voltage-power frequency electrical heating in-situ conversion technology is a very promising in-situ pyrolysis method,which could provide a new way of mining oil shale resources.

Sun, Youhong; Yang, Yang; Lopatin, Vladimir; Guo, Wei; Liu, Baochang; Yu, Ping; Gao, Ke; Ma, Yinlong

2014-05-01

87

Abstract--This paper presents an intra-process dynamic voltage and frequency scaling (DVFS) technique targeted toward  

E-print Network

models that allow the CPU to calculate the expected workload and slack time for the next time slot, and thus, adjust its voltage and frequency in order to save energy while meeting soft timing constraints

Pedram, Massoud

88

All-Polymer modulator for high frequency low drive voltage applications  

NASA Astrophysics Data System (ADS)

Organic electro-optic material based optical modulators have been fervently pursued over the past two decades. The material properties of organic materials over crystalline electro-optic materials such as LiNbO3 have yielded devices with record low drive voltages and significant promise for high frequency operation that are ideal for implementation in many developing telecommunication technologies. This paper will discuss a TM electro-optic phase modulator based on a recently developed material IKD-1-50. A simple fabrication process that is compatible with wafer scale manufacturability using commercially available cladding materials, spin processing, standard photolithography, and dry etching will be presented. Non-centrosymmetric order is induced in the core material via a thermally enabled poling process that was developed based on work in simple slab waveguide material characterization devices, and optimized for polymer stack waveguide architectures. Basic phase modulators are characterized for half wave voltage and optical loss. In device r33 values are estimated from a combination of measured and simulated values. Additional work will be discussed including amplitude modulation and high frequency applications. The design for a Mach-Zehnder interferometer amplitude modulator that implements a multi mode interference cavity splitter will be presented along with plans for a microstrip transmission line traveling wave modulator.

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

2014-03-01

89

Comparison of Transient and Power Frequency-Induced Voltages on a Pipeline Parallel to an Overhead Transmission Line  

Microsoft Academic Search

An analysis of the voltages induced on a 1-km pipeline by a parallel overhead transmission line has been carried out when the transmission line is carrying power frequency (50 Hz) current and when it is subject to the propagation of a lightning or switching transient. A frequency-based circuit modeling technique coupled with forward and inverse Fourier transforms is used to

Ian Cotton; Konstantinos Kopsidas; Yang Zhang

2007-01-01

90

A High Frequency Active Voltage Doubler in Standard CMOS Using Offset-Controlled Comparators for Inductive Power Transmission  

PubMed Central

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 mm2 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

2014-01-01

91

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

92

A very low noise, high accuracy, programmable voltage source for low frequency noise measurements.  

PubMed

In this paper an approach for designing a programmable, very low noise, high accuracy voltage source for biasing devices under test in low frequency noise measurements is proposed. The core of the system is a supercapacitor based two pole low pass filter used for filtering out the noise produced by a standard DA converter down to 100 mHz with an attenuation in excess of 40 dB. The high leakage current of the supercapacitors, however, introduces large DC errors that need to be compensated in order to obtain high accuracy as well as very low output noise. To this end, a proper circuit topology has been developed that allows to considerably reduce the effect of the supercapacitor leakage current on the DC response of the system while maintaining a very low level of output noise. With a proper design an output noise as low as the equivalent input voltage noise of the OP27 operational amplifier, used as the output buffer of the system, can be obtained with DC accuracies better that 0.05% up to the maximum output of 8 V. The expected performances of the proposed voltage source have been confirmed both by means of SPICE simulations and by means of measurements on actual prototypes. Turn on and stabilization times for the system are of the order of a few hundred seconds. These times are fully compatible with noise measurements down to 100 mHz, since measurement times of the order of several tens of minutes are required in any case in order to reduce the statistical error in the measured spectra down to an acceptable level. PMID:24784633

Scandurra, Graziella; Giusi, Gino; Ciofi, Carmine

2014-04-01

93

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

Microsoft Academic Search

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

Hirofumi Akagi; Takafumi Doumoto

2004-01-01

94

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

E-print Network

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

Hava, Ahmet

95

Direct torque control of permanent magnet synchronous motors with non-sinusoidal back-EMF  

E-print Network

torque response due to the fact that the voltage space vectors are directly controlled.. Finally, the position sensorless direct torque and indirect flux control (DTIFC) of BLDC motor with non-sinusoidal back-EMF has been extensively investigated using...

Ozturk, Salih Baris

2009-05-15

96

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

97

Force Sensor Characterization Under Sinusoidal Excitations  

PubMed Central

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

Medina, Nieves; de Vicente, Jesús

2014-01-01

98

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

E-print Network

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

Catholic University of Chile (Universidad Católica de Chile)

99

Pressure sensitive paint: application to a sinusoidal pressure fluctuation  

Microsoft Academic Search

An experimental characterization of the frequency response of a Pressure Sensitive Paint (PSP) has been performed. The PSP response to a sinusoidal pressure field was investigated. A Fourier analysis was then used to extended the results to a general periodic pressure field. Amplitude response and phase shift as a function of frequency are presented. The techniques developed in this paper

Bruce F. Carroll; Andy Winslow; John Abbitt; Kirk Schanze; Marty Morris

1995-01-01

100

1D wind model: sinusoidal piston  

E-print Network

1D wind model: sinusoidal piston For comparison, we also show a wind model with a sinusoidally moving piston and a corre­ sponding velocity amplitude of 5 km/s. This amplitude is comparable to the non­sinusoidal wind model (but with smaller temporal vari­ ations). A sinusoidal model with a piston

Freytag, Bernd

101

Optimum design of high frequency transformer for compact and light weight switch mode power supplies (SMPS)  

Microsoft Academic Search

In this paper a new approach for optimization of high frequency transformer design is presented. The presented design method is based on a restatement of the traditional transformer design equations to include non-sinusoidal switching waveforms and high frequency skin and proximity effects. In this optimization procedure both electric and thermal effects in the transformer is considered. Wave form of voltage

H. R. Karampoorian; P. Gh; A. Vahedi; A. Zadehgol

2006-01-01

102

Sinusoidal phase modulating interferometry system for 3D profile measurement  

NASA Astrophysics Data System (ADS)

We describe a fiber-optic sinusoidal phase modulating (SPM) interferometer for three-dimensional (3D) profilometry, which is insensitive to external disturbances such as mechanical vibration and temperature fluctuation. Sinusoidal phase modulation is created by modulating the drive voltage of the piezoelectric transducer (PZT) with a sinusoidal wave. The external disturbances that cause phase drift in the interference signal and decrease measuring accuracy are effectively eliminated by building a closed-loop feedback system. The phase stability can be measured with a precision of 2.75 mrad, and the external disturbances can be reduced to 53.43 mrad for the phase of fringe patterns. By measuring the dynamic deformation of the rubber membrane, the RMSE is about 0.018 mm, and a single measurement takes less than 250 ms. The feasibility for real-time application has been verified.

En, Bo; Fa-jie, Duan; Chang-rong, Lv; Fu-kai, Zhang; Fan, Feng

2014-07-01

103

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

NASA Astrophysics Data System (ADS)

Variable Energy Cyclotron Centre has commissioned a K-500 superconducting cyclotron for various types of nuclear physics experiments. The 3-phase radio-frequency system of superconducting cyclotron has been developed in the frequency range 9-27 MHz with amplitude and phase stability of 100 ppm and ±0.20, respectively. The analysis of the RF cavity has been carried out using 3D Computer Simulation Technology (CST) Microwave Studio code and various RF parameters and accelerating voltages ("Dee" voltage) are calculated from simulation. During the RF system commissioning, measurement of different RF parameters has been done and absolute Dee voltage has been calibrated using a CdTe X-ray detector along with its accessories and known X-ray source. The present paper discusses about the measured data and the simulation result.

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

2013-02-01

104

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

PubMed

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

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

2013-02-01

105

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

SciTech Connect

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

Som, Sumit; Seth, Sudeshna; Mandal, Aditya; Paul, Saikat; Duttagupta, Anjan [Variable Energy Cyclotron Centre, Kolkata (India)

2013-02-15

106

Effects of driving voltage frequency on the discharge characteristics of atmospheric dielectric-barrier-discharge plasma jet  

NASA Astrophysics Data System (ADS)

We present here the analysis of the discharge characteristics of a He dielectric-barrier-discharge (DBD) plasma jet operated in the frequency range of 0.6 to 30 kHz under an open-air condition. Discharge strength is sensitive to driving voltage frequency, and an increasing driving frequency induces a weak pulse discharge with a small plume length. We also performed time-resolved optical emission measurements in a transient pulse discharge driven by various voltage frequencies. A strong optical emission from O atoms is observed near the quartz-tube outlet at a low driving voltage frequency of about 5 kHz, where more than 90% of the total O emission intensity is detected in the after-discharge period. The observations indicate that low-frequency discharge operation can generate a large number of reactive excited O atoms near the quartz-tube outlet, and this is ascribed to the chemical reactions in the after-discharge period.

Uchida, Giichiro; Takenaka, Kosuke; Kawabata, Kazufumi; Miyazaki, Atsushi; Setsuhara, Yuichi

2014-11-01

107

Distributed Voltage and Frequency Control of Offshore Wind Farms Connected With a Diode-Based HVdc Link  

Microsoft Academic Search

This paper introduces a new technique for the distributed voltage and frequency control of the local ac-grid in offshore wind farms based on synchronous generators. The proposed control technique allows the connection of the offshore wind farm using a diode based HVdc rectifier. The use of microgrid control techniques allowed the system comprising the wind farm and the diode HVdc

Ramon Blasco-Gimenez; S. Año?-Villalba; J. Rodri?guez-D'Derle?e; F. Morant; S. Bernal-Perez

2010-01-01

108

High-frequency level-up shifter based on 0.18 µm vertical metal–oxide–semiconductor field-effect transistors with 70% reduction of overshoot voltage above power supply voltage  

NASA Astrophysics Data System (ADS)

A high-frequency and high-voltage-tolerant level-up shifter is proposed. In the design, a voltage limiter with a preset and a dynamic biasing feedback circuit are introduced. In a typical simulation, our circuit based on 0.18 µm vertical metal–oxide–semiconductor field-effect transistors (MOSFETs) shows a 70% reduction of the overshoot voltage of the MOSFETs above the power supply voltage (1.8 V VDD) compared with a conventional circuit. It realizes a typical operation frequency of 164 MHz when the maximum voltage applied to all MOSFETs is limited to 1.8 V. The maximum achievable operation frequency is more than 1.6 times that of a conventional circuit. The variation of the maximum voltage applied to the MOSFETs in our circuit is also reduced by about 24% compared with that of the conventional circuit in a process-corner simulation with the variation of VDD and temperature.

Tanoi, Satoru; Endoh, Tetsuo

2015-04-01

109

Regenerator performance with sinusoidal flow  

NASA Technical Reports Server (NTRS)

The ineffectiveness of regenerators with sinusoidal laminar flow through parallel plate, screen, and packed sphere matrices is evaluated in the limit of infinite matrix heat capacity. Increases in ineffectiveness of up to 23 percent over the constant flow values result for parallel plate regenerators.

Daney, D. E.

1991-01-01

110

Zero-voltage-switching PWM inverter for high-frequency DC-AC power conversion  

Microsoft Academic Search

A zero-voltage-switching (ZVS) three-phase pulse width modulated (PWM) inverter which uses a parallel-resonant DC-link (PRDCL) circuit proposed by J. He and N. Mohan (1989) is examined. The PRDCL circuit is aimed at both providing zero-DC link voltage periods for PWM inverter switchings and imposing minimum DC bus voltage stress to PWM inverters. A simple circuit control scheme and the design

J. He; N. Mohan; B. Wold

1993-01-01

111

Zero-voltage-switching PWM inverter for high-frequency DC-AC power conversion  

Microsoft Academic Search

A zero voltage switching (ZVS) pulse-width modulation (PWM) inverter that uses a parallel-resonant DC link (PRDCL) circuit is examined. The PRDCL circuit provides zero-DC link voltage periods for the inverter switchings and imposes minimum DC bus voltage stress on the PWM inverter. A simple circuit control scheme and the design formulae are presented. To confirm the analytical and simulation results

Jin He; Ned Mohan; Bill Wold

1990-01-01

112

Zero-voltage-switching PWM inverter for high-frequency dc-ac power conversion  

Microsoft Academic Search

A zero-voltage-switching (ZVS) three-phase PWM inverter which uses a newly proposed Parallel-Resonant DC-Link (PRDCL) circuit is further examined in this paper. The proposed PRDCL circuit is aimed at both providing zero-dc-link voltage periods for PWM inverter switchings and imposing minimum dc bus voltage stress to PWM inverters. A simple circuit control scheme and the design formulas are offered. To confirm

Jin He; N. Mohan; B. Wold

2009-01-01

113

Volume and loss optimization of high frequency transformer for compact switch mode power supply considering corrected waveform factor  

Microsoft Academic Search

A new procedure for optimum design of high frequency transformers is presented. The presented design method is based on a restatement and correction of the traditional transformer design equations to include non-sinusoidal switching waveforms and high frequency skin and proximity effects. In this optimization procedure both electric and thermal effects in the transformer is considered. Wave form of voltage and

H. R. Karampoorian; Gh. Papi; A. Zadehgol

2006-01-01

114

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

Microsoft Academic Search

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

Douglas C. Duckworth; R. Kenneth Marcus; David L. Donohue; Trousdale A. Lewis

1994-01-01

115

Response of Mains Connected Induction Motors to Low Frequency Voltage Fluctuations from a Flicker Perspective  

Microsoft Academic Search

In radial power systems flicker transfer from a higher voltage level (upstream) to a lower voltage level (down- stream) is seen to be significantly affected by the down- stream load composition. Industrial load bases contain- ing mains connected induction motors are known to be effective in the flicker attenuation process compared to residential load bases containing passive loads. For better

Sankika Tennakoon; Sarath Perera; Duane Robinson

116

Effect of extremely low frequency electromagnetic field exposure on sleep quality in high voltage substations  

PubMed Central

This study aims to investigate the effect of extremely low frequency electromagnetic fields exposure on sleep quality in high voltage substations (132, 230 and 400 KV) in Kerman city and the suburbs. For this purpose, the electric field intensity and magnetic flux density were measured in different parts of substations, and then the occupational exposure was estimated by averaging electric field intensity and magnetic flux density in a shift work. The cases comprised 67 workers who had been exposed to electromagnetic fields in age range of 24–57 and the controls were 110 persons the age ranged 24–50 years. Sleep quality of both groups was evaluated by the Pittsburgh Sleep Quality Index questionnaire (PSQI). Finally, these data were subjected to statistical analysis. The results indicated that 90.5% of cases and 85.3% of controls had the poor quality sleep according to PSQI (P-value=0.615). Total sleep quality score mean for the case and control groups were 10.22?±?3.4 and 9.74?±?3.62 (P-value=0.415) ,respectively. Meantime to fall asleep for cases(35.68?±?26.25 min) was significantly higher than for controls (28.89?±?20.18 min) (P-value=0.002). Cases had average sleep duration of 5.49?±?1.31 hours, which was lower ascompared with control subjects (5.90?±?1.67hours). Although there was a higher percentage for the case group with poor sleep quality than the control group, but no statistically significant difference was observed. PMID:23369281

2012-01-01

117

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

PubMed Central

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

Asgarifar, Hajarossadat; Oloyede, Adekunle; Zare, Firuz

2014-01-01

118

The Digital Simulation of Synchronous Motors Fed by Voltage-Source Inverters Over Wide Speed and Frequency Ranges  

NASA Astrophysics Data System (ADS)

Both voltage-source and current-source inverters are widely used for supplying three-phase power to induction motor drives, each having their advantages and disadvantages. For high power drives and applications requiring accurate speed and tracking coordination, the synchronous motors are the optimum choice. For constant speed applications of synchronous motor drives, current-source inverters tend to be favored as the motor can usually be operated in the overexcited leading power factor region, thus providing the inverter with sufficient electro-motive force to allow natural commutation. Generally speaking low speed operation of synchronous motors is not satisfactory from naturally commutated current-source inverters. To provide a dynamic range of speed and frequency would require expensive control circuitry and complicates the performance of the drive. The advantage of the voltage-source inverter for the wide range of speed and frequency control herein envisaged is that forced commutation is employed throughout the range and the commutating circuits have been well developed and established. On balance, voltage-source inverters represent a viable compromise for variable-speed three -phase synchronous motor drives including start-up. To investigate the transient response of the voltage -source fed-synchronous motor drives, a digital computer program is developed. The program is based on two models --machine model and inverter model. The machine is represented by a detailed two-axis model which includes the effects due to saliency, damper windings, and machine resistances. The inverter model represents a forced-commutated voltage-source inverter assuming ideal switching devices (thyristors and diodes). To cope with the wide variations of power factor during start-up, a thyristor with a reverse connected parallel diode are integrated as a bidirectional switch. The digital program provides the machine variables of interest (phase currents, field current, damper winding currents, and electromagnetic torque). Two start-up techniques are investigated: fixed-frequency fixed-voltage start-up and variable-frequency start-up with constant voltage per Hertz ratio (v/f) control. The second technique has valuable consequences because it relieves the stresses imposed on the inverter and the motor due to inrush currents encountered when the first technique is employed. Simulation results are obtained for both start-up techniques. To check the validity of the inverter model, the results are compared with those obtained when the motor is started from a conventional three-phase supply. (Abstract shortened with permission of author.).

Rowihal, Said Soliman

119

Speech analysis\\/Synthesis based on a sinusoidal representation  

Microsoft Academic Search

A sinusoidal model for the speech waveform is used to develop a new analysis\\/synthesis technique that is characterized by the amplitudes, frequencies, and phases of the component sine waves. These parameters are estimated from the short-time Fourier transform using a simple peak-picking algorithm. Rapid changes in the highly resolved spectral components are tracked using the concept of \\

R. McAulay; T. Quatieri

1986-01-01

120

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

121

Tri-Mode Independent-Gate FinFETs for Dynamic Voltage\\/Frequency Scalable 6T SRAMs  

Microsoft Academic Search

In this paper, we present tri-mode independent-gate (IG) FinFETs for dynamic voltage\\/frequency scalable 6T SRAMs. The proposed design exploits the fact that the spacer patterning technology, used for FinFET fabrication, offers the same device footprint for two- and one-fin transistors. The access transistor is designed for operation in three ON-state modes achieving simulta- neous increase in the read stability and

Sumeet Kumar Gupta; Sang Phill Park; Kaushik Roy

2011-01-01

122

DC AND HIGH-FREQUENCY VOLTAGE AND POWER OUTPUT AND INTERACTION IN CESIUM, POTASSIUM AND SODIUM THERMIONIC CONVERTERS  

Microsoft Academic Search

A plasma diode with a Ta emitter and Mo collector and guardring was ; operated with Cs, K, and Na vapors. The emitter-collector-distance, vapor ; pressure, and emitter temperature were varied during the experiments. An ; inductance -capacitance network separated the d-c output from the high frequency ; r-f component and permitted study of interaction between d-c and r-f voltage,

1963-01-01

123

Distributed voltage and frequency control of off-shore wind farms connected with a diode based HVDC link  

Microsoft Academic Search

This paper introduces a new technique for the distributed voltage and frequency control of the local ac-grid in off-shore wind farms based on synchronous generators. The proposed control technique allows the connection of the off-shore wind farm using a diode based HVDC rectifier. The system comprising the wind farm and the diode HVDC rectifier can be operated in current or

R. Blasco-Gimenez; S. An?o?-Villalba; J. Rodri?guez-D?Derle?e; F. Morant; S. Bernal

2010-01-01

124

A PFC pre-regulator with 110 V\\/220 V input voltage and high frequency isolation for UPS applications  

Microsoft Academic Search

This work deals with the development of a PFC pre-regulator circuit with possibility of 110 V\\/220 V AC main input voltages, while maintaining the same efficiency for a wide load range. Other relevant features of this circuit topology are high frequency transformer isolation, soft commutation of the controlled switches, simple control strategy that can be implemented with well-known integrated circuits

René P. Torrico-Bascopé; Demercil S. Oliveira Jr; Carlos G. C. Branco; Fernando L. M. Antunes

2005-01-01

125

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

126

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

127

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

Microsoft Academic Search

The utility grid voltage of commercial AC power source in Japan and USA is 100V, but in other Asian and European countries, it is 220V. In recent years, in Japan 200V outputted single-phase three-wire system begins to be used for high power applications. In 100V utility AC power applications and systems, an active voltage clamped quasi-resonant inverter circuit topology sing

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

2004-01-01

128

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

NASA Astrophysics Data System (ADS)

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

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

2013-11-01

129

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

SciTech Connect

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

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

2013-11-21

130

High frequency capacitor-diode voltage multiplier dc-dc converter development  

NASA Technical Reports Server (NTRS)

A power conditioner was developed which used a capacitor diode voltage multiplier to provide a high voltage without the use of a step-up transformer. The power conditioner delivered 1200 Vdc at 100 watts and was operated from a 120 Vdc line. The efficiency was in excess of 90 percent. The component weight was 197 grams. A modified boost-add circuit was used for the regulation. A short circuit protection circuit was used which turns off the drive circuit upon a fault condition, and recovers within 5 ms after removal of the short. High energy density polysulfone capacitors and high speed diodes were used in the multiplier circuit.

Kisch, J. J.; Martinelli, R. M.

1977-01-01

131

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

NASA Technical Reports Server (NTRS)

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

Riaz, M.

1970-01-01

132

Adaptive Digital Controller and Design Considerations for a Variable Switching Frequency Voltage Regulator  

Microsoft Academic Search

An auto-tuning adaptive digital controller with maximum efficiency point tracking to optimize dc-dc converter switching frequency is presented in this paper. The adaptive-frequency-optimization (AFO) controller adjusts the dc-dc converter switching frequency while tracking the converter minimum input power (maximum efficiency) point under variable operation conditions of the power converter. The AFO digital controller continuously finds the optimum switching frequency that

Wisam Al-Hoor; Jaber A. Abu-Qahouq; Lilly Huang; Wasfy B. Mikhael; Issa Batarseh

2009-01-01

133

Low-voltage polyphasic circuits  

NASA Astrophysics Data System (ADS)

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

Baird, William H.; Jaynes, Michael L.

2010-05-01

134

Power quality issues with adjustable frequency drives -- Coping with power loss and voltage transient occurrences  

SciTech Connect

The power quality issue is not new to consumers of electrical power. From individual home owners to large industrial complexes, power quality problems can cause eyebrows to raise or bring industrial giants to their knees. Power quality comes in many forms. It can appear in the form of a voltage source which decreases to a small fraction of its normal strength or as a voltage transient, briefly far exceeding its normal value, ready to break down electrical insulation. It can appear as an oscillating voltage or a traveling voltage wave beating against barriers designed as added protection. Defining a single set of rules to control the characteristics of power quality is difficult, since its impact on electrical equipment changes as the characteristics of equipment change. A key to understanding how to cope with power quality issues begins with understanding the nature of electrical products. The nature of any product is defined by how its components are selected and how the designers apply those components. Reviewing design criteria, component selection and product characteristics can provide this basis of understanding.

Murphy, H.G. (Allen-Bradley Co., Mequon, WI (United States))

1993-07-01

135

Sinusoidal heating method to noninvasively measure tissue perfusion.  

PubMed

Noninvasively measuring the tissue blood perfusion has been an important however difficult problem in the biomedical engineering field. Based on the newly developed phase-shift principle, an improved sinusoidal heating method to estimate the perfusion was proposed in this paper to replace the original heating algorithm. The phase shift between the sinusoidal heat flux and the surface temperature response was both theoretically and experimentally revealed to be a time-dependent value which however will approach a constant value after a sufficiently long time. Only using this constant phase shift can the perfusion be properly estimated. Following the theory, an instrument consisting of low-frequency sinusoidal signal generator, power amplifier, heating plate, temperature and heat flux monitoring unit, as well as the data-acquisition system was carefully constructed. It allows generating a high-quality sinusoidal heat flux whose frequency and magnitude can be easily regulated. An auxiliary heat-conducting plate was introduced to simultaneously measure the surface temperature and the heat flux, which are hard to do otherwise. Experiments on human bodies were performed and the forearm perfusion was estimated and then validated through a constant surface heating experiment. Several issues related to the instrument integration and perfusion measurement were discussed. The instrument was also tested through experiments on nonperfused materials and good results were obtained. These efforts will help to build a compact device for noninvasively measuring the human perfusion, which may have significant applications in future clinics. PMID:12148826

Liu, Jing; Zhou, Yi-Xin; Deng, Zhong-shan

2002-08-01

136

Monitoring voltage-dependent charge displacement of Shaker B-IR K+ ion channels using radio frequency interrogation.  

PubMed

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 Cu(2+) addition to the external bath. Cu(2+) 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 Cu(2+)-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. PMID:21387000

Dharia, Sameera; Rabbitt, Richard D

2011-01-01

137

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. PMID:21387000

Dharia, Sameera; Rabbitt, Richard D.

2011-01-01

138

Impedance of the electrogenic Cl(-) pump inAcetabularia: Electrical frequency entrainements, voltage-sensitivity, and reaction kinetic interpretation.  

PubMed

Reaction kinetic analysis of the electrical properties of the electrogenic Cl(-) pump inAcetabularia has been extended from steady-state to nonsteady-state conditions: electrical frequency responses of theAcetabularia membrane have been measured over the range from 1 Hz to 10 kHz at transmembrane potential differences across the plasmalemma (V m ) between -70 and -240 mV using voltage-clamp techniques. The results are well described by an electrical equivalent circuit with three parallel limbs: a conventional membrane capacitancec m , a steadystate conductanceg o (predominantly of the pump pathway plus a minor passive ion conductance) and a conductanceg s in series with a capacitancec p which are peculiar to the temporal behavior of the pump. The absolute values and voltage sensitivities of these four elements have been determined:c m of about 8 mF m(-2) turned out to be voltage insensitive; it is considered to be normal.g o is voltage sensitive and displays a peak of about 80 S m(-2) around -180 mV. Voltage sensitivity ofg s could not be documented due to large scatter ofg s (around 80 S m(-2)).c p behaved voltage sensitive with a notch of about 20 mF m(-2) around -180 mV, a peak of about 40 mF m(-2) at -120 mV and vanishing at -70 mV. When these data are compared with the predictions of nonsteady-state electrical properties of charge transport systems (U.-P. Hansen, J. Tittor, D. Gradmann, 1983,J. Membrane Biol. in press), model "A" (redistribution of states within the reaction cycle) consistently provides magnitude and voltage sensitivity of the elementsg o ,g s andc p of the equivalent circuit, when known kinetic parameters of the pump are used for the calculations. This analysis results in a density of pump elements in theAcetabularia plasmalemma of about 50 nmol m(-2). The dominating rate constants for the redistribution of the individual states of the pump in the electric field turn out to be in the range of 500 sec(-1), under normal conditions. PMID:25691373

Tittor, J; Hansen, U P; Gradmann, D

1983-07-01

139

Frequency and gate voltage effects on the dielectric properties and electrical conductivity of Al/SiO2/p-Si metal-insulator-semiconductor Schottky diodes  

NASA Astrophysics Data System (ADS)

The dielectric properties and electrical conductivity of Al/SiO2/p-Si (MIS) Schottky diodes (SDs) in the frequency range of 10 kHz to 10 MHz and the gate voltage range of -2 to 6 V have been investigated in detail using experimental C-V and G/w-V measurements. Experimental results indicated that the voltage dependence of the real part of the dielectric constant (?') and loss tangent (tan ?) characteristics have a peak at each frequency. The values of ?' increase with decreasing frequency and tend to be frequency independent in the negative voltage region. However, the values of the dielectric loss (??) increase with decreasing frequency at each voltage. In contrast, ?' and ?? are almost found to decrease, and the ac electrical conductivity (?ac) and the real part of the electric modulus (M') increase, with increasing frequency. In addition, the imaginary part of the electric modulus (M?) showed a peak that shifts to a higher frequency with increasing applied voltage. It can be concluded that interfacial polarization can more easily occur at low frequencies, and consequently the majority of interface states at the Si-SiO2 interface contribute to the deviation of the dielectric properties of Al/SiO2/p-Si (MIS) SDs.

Y?ld?z, D. E.; Dökme, I.

2011-07-01

140

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

SciTech Connect

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

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

2014-02-12

141

Issues on the design and implementation of radio frequency CMOS LC tank voltage-controlled oscillators  

Microsoft Academic Search

This paper is a general tutorial on the design and implementation of integrated submicron CMOS voltage-controlled oscillators\\u000a based on LC resonator tanks. Although special reference to phase noise reduction is made, the discussion also includes issues\\u000a such as power consumption, oscillator reliability and adaptivity together with tuning range. Important guidelines on oscillator\\u000a and LC tank design are discussed, with emphasis

Owen Casha; Ivan Grech; Joseph Micallef

2009-01-01

142

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

E-print Network

of microwave oscillators, and adapted to the optical domain by Drever et al.2 In brief, the source to the optical implementation of Pound-Drever-Hall, but which uses RF electronics rather than optical equipment is commonly applied to stabilize lasers at optical frequencies. By using only radio- frequency equipment

Le Roy, Robert J.

143

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

144

Kerr-effect Studies of an Insulating Liquid under Varied High-Voltage Conditions  

Microsoft Academic Search

Refined Kerr electrooptical fringe-pattern methods are used to study time and space variations in the electric field between the electrodes of parallel-plate capacitors filled with liquid nitrobenzene. Photographs of fringe-pattern data recorded during application of high direct (both positive and negative) and sinusoidal voltages, ranging in frequency from 40 to 200 Hz, are compiled to enable computation of space-charge distortions

ESTHER CHRISTMASCASSIDY; Robert Hebner; Markus Zahn; Richard Sojka

1974-01-01

145

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

SciTech Connect

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

Wessendorf, K.O.

1996-08-01

146

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

147

Effect of Radio-Frequency and Low-Frequency Bias Voltage on the Formation of Amorphous Carbon Films Deposited by Plasma Enhanced Chemical Vapor Deposition  

NASA Astrophysics Data System (ADS)

The effect of radio-frequency (RF) or low-frequency (LF) bias voltage on the formation of amorphous hydrogenated carbon (a-C:H) films was studied on silicon substrates with a low methane (CH4) concentration (2–10 vol.%) in CH4+Ar mixtures. The bias substrate was applied either by RF (13.56 MHz) or by LF (150 kHz) power supply. The highest hardness values (~18–22 GPa) with lower hydrogen content in the films (~20 at.%) deposited at 10 vol.% CH4, was achieved by using the RF bias. However, the films deposited using the LF bias, under similar RF plasma generation power and CH4 concentration (50 W and 10 vol.%, respectively), displayed lower hardness (~6–12 GPa) with high hydrogen content (~40 at.%). The structures analyzed by Fourier Transform Infrared (FTIR) and Raman scattering measurements provide an indication of trans-polyacetylene structure formation. However, its excessive formation in the films deposited by the LF bias method is consistent with its higher bonded hydrogen concentration and low level of hardness, as compared to the film prepared by the RF bias method. It was found that the effect of RF bias on the film structure and properties is stronger than the effect of the low-frequency (LF) bias under identical radio-frequency (RF) powered electrode and identical PECVD (plasma enhanced chemical vapor deposition) system configuration.

Hadar, Manis-Levy; Tsachi, Livneh; Ido, Zukerman; Moshe, H. Mintz; Avi, Raveh

2014-10-01

148

Human Performance and Transmissibility under Sinusoidal and Mixed Vertical Vibration  

Microsoft Academic Search

Six subjects performed a four-limb coordination task on a shaker table driven by both single sinusoidal frequencies of 2.5 Hz and 5.0 Hz, as well as by an electronic mixture of 2.5 Hz and 5.0 Hz. Vibration acceleration was held constant at 0.09 ms (0,07 gz) rms, i.e., a level below the international standard ‘ fatigue-decresed proficiency ’ boundary for

H. HARVEY COHEN; DONALD E. WASSERMAN; RICHARD W. HORNUNG

1977-01-01

149

Sinusoidal voltage controlled oscillators using operational transconductance amplifiers  

E-print Network

limfters and the other kard l&'mitcrs. I'rom I'igure 4. 1 hard lirniters will have the slope n&2 equal to zero. The output signal will be choped at some value. The degree of softness oi' the limiter will depend on the value of m2. The bigger m2... Page I INTRODUCTION 1. 1 OTA Model 1. 2 OTA Building Block 1. 3 OTA lntegrators 1. 4 Biasing Techniques 1. 5 Summary and Thesis Overview 2 3 6 10 13 II OSCILLATORS 2. 1 Principal of Operation 2. 2 Quadrature Oscillators 2. 3 Bandpass...

Hoyle Passano, Javier Joaquin

1985-01-01

150

Voltage-Sensitive Dye Imaging of Neocortical Spatiotemporal Dynamics to Afferent Activation Frequency  

Microsoft Academic Search

The spatial and temporal patterns of neocortex activation are determined not only by the dynamic character of the input but also by the intrinsic dynamics of the cortical circuitry. To study the role of afferent input frequency on cortical activation dy- namics, the electrical activity of in vitro neocortex slices was imaged during white-matter electrical stimulation. High-speed optical imaging was

Diego Contreras; Rodolfo Llinas

2001-01-01

151

A nonlinear filter for estimating a sinusoidal signal and its parameters in white noise: on the case of a single sinusoid  

Microsoft Academic Search

A nonlinear filter is proposed for estimating a complex sinusoidal signal and its parameters (frequency, amplitude, and phase) from measurements corrupted by white noise. This filter is derived by applying an extended complex Kalman filter (ECKF) to a nonlinear stochastic system whose state variables are a function of its frequency and a sample of an original signal, and then, proof

Kiyoshi Nishiyama

1997-01-01

152

Performance evaluation of half-bridge cascaded multilevel converters operated with multicarrier sinusoidal PWM techniques  

Microsoft Academic Search

High-power high-voltage power electronics systems with fully-controlled semiconductors can benefit from the development of modular solutions based on voltage-sourced building blocks. This paper offers a performance comparison of various multicarrier sinusoidal pulse width modulation (PWM) techniques for the control of the modular multilevel converter (MMC) based on the half-bridge capacitor cell. It is found that the PWM method can significantly

Georgios S. Konstantinou; Vassilios G. Agelidis

2009-01-01

153

Galalctic Tides & the Sinusoidal Potential  

NASA Astrophysics Data System (ADS)

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

Bartlett, David F.

2011-05-01

154

Quantization noise spectrum of double-loop sigma-delta converter with sinusoidal input  

Microsoft Academic Search

An exact formula for the output noise spectrum of a double-loop sigma-delta modulator, under the no overloading assumption and with a sinusoidal input, is derived without the use of a white-noise model. In the case of a sinusoidal input with irrational input amplitude and digital frequency, the result agrees with the exact formula derived by ergodic theory for two-stage modulators.

S. Rangan; B. Leung

1994-01-01

155

Quantization noise spectrum of double-loop sigma-delta converter with sinusoidal input  

Microsoft Academic Search

An exact formula for the output noise spectrum of a double-loop sigma-delta modulator with a sinusoidal input is derived without the use of a white-noise model. In the case of a sinusoidal input with irrational input amplitude and digital frequency, the result agrees with the exact formula derived by ergodic theory for two-stage modulators. In addition, the present method also

Sundeep Rangan; Bosco Leung

1993-01-01

156

A 300 mV sub-threshold region 2.4 GHz voltage-controlled oscillator and frequency divider with transformer technique for ultralow power RF applications  

NASA Astrophysics Data System (ADS)

A new ultralow voltage 2.4 GHz voltage-controlled oscillator (VCO) and a divide-by-2 frequency divider circuits operating in a CMOS sub-threshold region using a transformer technique have been developed. In the sub-threshold region, the CMOS transistor high frequency performances are decreased to the point where oscillation and frequency division are challenging to achieve. The new proposed VCO uses the transformer feedback complementary VCO technique to improves VCO negative feedback gain. The circuits have been fabricated in a 65 nm standard CMOS process. The oscillation frequency is designed at 2.4 GHz under a 300 mV supply voltage. The total power consumption is 202 µW with noise performance of -96 dBc/Hz at 1 MHz offset. The new proposed frequency divider circuit consists of two stages master-slave D-type flip-flop (DFF). The DFF differential input is coupled to a transformer circuit instead of transistors to reduce the number of stacks. The minimum operating supply voltage is 300 mV with power consumption of 34 µW with a free-run frequency of 1.085 GHz.

Miyahara, Yasunori; Ishikawa, Keisuke; Kuroda, Tadahiro

2014-01-01

157

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

SciTech Connect

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

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

2008-09-15

158

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

159

One-dimensional plasma photonic crystals with sinusoidal densities  

SciTech Connect

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

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

2014-01-15

160

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

NASA Astrophysics Data System (ADS)

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

Shinnaka, Shinji

161

Dilatation of sinusoidal capillary and swelling of sinusoidal fenestration in obesity: an ultrastructural study.  

PubMed

Obesity, which is one of the causes of the lifestyle-related disease, is a hepatopathic exacerbation factor that causes a chronic hepatic disorder. In this study, we examined the pathological changes in the liver in mice with obesity induced by monosodium glutamate administration. Pathological analysis revealed the deposition of many lipid droplets in hepatocytes and sinusoidal dilatation in obese mice. Scanning electron microscopic analysis revealed the presence of sinusoidal dilatation, and the fenestrations of the sinusoid were significantly swollen in obese mice. These results suggest that a dysfunction of the sinusoidal endothelium occurs in chronic obesity. PMID:25192055

Nakadate, Kazuhiko; Motojima, Kento; Tanaka-Nakadate, Sawako

2015-02-01

162

Effects of Bias Voltage on the Structure and Mechanical Properties of Thick CrN Coatings Deposited by Mid-Frequency Magnetron Sputtering  

NASA Astrophysics Data System (ADS)

Thick CrN coatings were deposited on Si (111) substrates by electron source assisted mid-frequency magnetron sputtering working at 40 kHz. The deposition rate, structure, and microhardness of the coatings were strongly influenced by the negative bias voltage (Vb). The deposition rate reached 8.96 ?m/h at a Vb of -150 V. X-ray diffraction measurement revealed strong CrN (200) orientation for films prepared at low bias voltages. At a high bias voltage of Vb less than -25 V both CrN (200) and (111) were observed. Large and homogeneous grains were observed by both atomic force microscopy and scanning electron microscopy in samples prepared under optimal conditions. The samples exhibited a fibrous microstructure for a low bias voltage and a columnar structure for Vb less than -150 V.

Rong, Shuangquan; He, Jun; Wang, Hongjun; Tian, Canxin; Guo, Liping; Fu, Dejun

2009-02-01

163

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

NASA Astrophysics Data System (ADS)

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

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

164

An Adaptive Filter for the Removal of Drifting Sinusoidal Noise without a Reference.  

PubMed

This paper presents a method for filtering sinusoidal noise with a variable bandwidth filter that is capable of tracking a sinusoid's drifting frequency. The method, which is based on the adaptive noise canceling (ANC) technique, will be referred to here as the adaptive sinusoid canceler (ASC). The ASC eliminates sinusoidal contamination by tracking its frequency and achieving a narrower bandwidth than typical notch filters. The detected frequency is used to digitally generate an internal reference instead of relying on an external one as ANC filters typically do. The filter's bandwidth adjusts to achieve faster and more accurate convergence. In this paper the focus of the discussion and the data is physiological signals, specifically electrocorticographic (ECoG) neural data contaminated with power line noise, but the presented technique could be applicable to other recordings as well. On simulated data, the ASC was able to reliably track the noise's frequency, properly adjust its bandwidth, and outperform comparative methods including standard notch filters and an adaptive line enhancer (ALE). These results were reinforced by visual results obtained from real ECoG data. The ASC showed that it could be an effective method for increasing signal to noise ratio (SNR) in the presence of drifting sinusoidal noise, which is of significant interest for biomedical applications. PMID:25474814

Kelly, John; Siewiorek, Daniel; Smailagic, Asim; Wang, Wei

2014-12-01

165

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

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

166

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

NASA Astrophysics Data System (ADS)

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

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

2015-05-01

167

Power spectra of sinusoidal amplitude-modulated binary signals  

NASA Technical Reports Server (NTRS)

Power spectra for binary phase-shift keyed (PSK) and frequency-shift keyed (FSK) signals with combined sinusoidal amplitude modulation by the bit rate clock are presented. Such signal formats have application in 'burst' communication systems wherein reliable bit synchronization is provided with relative receiver simplicity. Effects of the clock amplitude modulation index and phase are considered, and corresponding power spectra are illustrated. Further, effects of the clock parameters on the rate of spectral rolloff are given and compared with those of conventional PSK and FSK spectra.

Gee, T. H.; Geist, J. M.

1976-01-01

168

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

169

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

This work presents an intraprocess dynamic voltage and frequency scaling (DVFS) technique targeted toward nonreal-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 performance

Kihwan Choi; Ramakrishna Soma; Massoud Pedram

2005-01-01

170

High voltage power supply  

NASA Technical Reports Server (NTRS)

A high voltage power supply is formed by three discrete circuits energized by a battery to provide a plurality of concurrent output signals floating at a high output voltage on the order of several tens of kilovolts. In the first two circuits, the regulator stages are pulse width modulated and include adjustable ressistances for varying the duty cycles of pulse trains provided to corresponding oscillator stages while the third regulator stage includes an adjustable resistance for varying the amplitude of a steady signal provided to a third oscillator stage. In the first circuit, the oscillator, formed by a constant current drive network and a tuned resonant network included a step up transformer, is coupled to a second step up transformer which, in turn, supplies an amplified sinusoidal signal to a parallel pair of complementary poled rectifying, voltage multiplier stages to generate the high output voltage.

Ruitberg, A. P.; Young, K. M. (inventors)

1985-01-01

171

Tunable OTA-based multiphase sinusoidal oscillators  

Microsoft Academic Search

Using a simple scheme, realisation of some novel multiphase sinusoidal oscillators (MPSOs) employing operational transconductance amplifiers (OTAs) as the active device are considered. These oscillators can provide n signals (n being odd) equal in amplitude as well as equally spaced in phase. Two practical OTA: RC three-phase oscillators have been realised and studied in detail. Their corresponding OTA-C realisations have

IQBAL A. KHAN; MUSLIM T. AHMED; NIGAR MINHAJ

1992-01-01

172

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

173

Generalized frequency modulation  

E-print Network

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

Torres, Wade Patrick

2001-01-01

174

Non-ideal characteristic analysis of GaN-based light-emitting diode using current-voltage (I–V) and low-frequency noise experiment  

Microsoft Academic Search

In order to investigate the reliability problem of the GaN-based light-emitting diode (LED), the non-ideal characteristics of the GaN-based LED were analyzed through current-voltage (I-V) and low-frequency noise experiment. Ideality factor, parasitic resistance and parasitic diode were considered to analyze the I-V characteristic. We could find that the parasitic diode makes the forward hump and divides the I-V curve into

Taewook Kang; Daeyoung Woo; Joong-Kon Son; Jong-Ho Lee; Byung-Gook Park; Hyungcheol Shin

2011-01-01

175

A novel control method for dual mode time-sharing cascaded sinusoidal inverter  

Microsoft Academic Search

Dual mode time-sharing cascaded sinusoidal inverter often has higher efficiency than other type DC\\/AC inverter. However, for this type inverter adopts a small DC-link chemical capacitor instead of a conventional electrolytic one, the control is easy to be disturbed by the ripple of input DC voltage. This paper proposes a new ldquoreal-timerdquo feed-forward control for the dual mode time-sharing cascaded

Weimin Wu; Pan Geng; Xiaoli Wang; Yingzhong Ye; Tianhao Tang

2008-01-01

176

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

177

Compensation of Moire Fringe Sinusoidal Deviation in Photoelectrical Encoder Based on Tunable Filter  

Microsoft Academic Search

In order to improve the precision of the absolute photoelectrical encoder, a compensating method is put forward, which restrains the harmonics in moiré fringe signal. After analyzing the relationship between the subdividing error and the sinusoidal index, a low-pass digital filter which can make the moiré signal satisfy the need of 1024 subdivision is designed. Considering with the fundamental frequency

Yan Wang; Yang Liu; Xiaojun Yan; Xinglin Chen; Hengyi Lv

2011-01-01

178

NON-LINEAR VIBRATION ABSORBER FOR A SYSTEM UNDER SINUSOIDAL AND RANDOM EXCITATION: EXPERIMENTS  

Microsoft Academic Search

A system consisting of a primary structure coupled with a passive tuned vibration absorber is experimentally studied. The primary structure consists of four flexible columns with a mass, while the absorber consists of a beam with a tip-mass. The system, which is a coupled non-linear oscillator, is subjected to sinusoidal and random excitation. The effects of the forcing frequency, forcing

O. Cuvalci; A. Ertas; S. Ekwaro-Osire; I. Cicek

2002-01-01

179

Human comfort in relation to sinusoidal vibration  

NASA Technical Reports Server (NTRS)

An investigation was made to assess the overall subjective comfort levels to sinusoidal excitations over the range 1 to 19 Hz using a two axis electrohydraulic vibration simulator. Exposure durations of 16 minutes, 25 minutes, 1 hour, and 2.5 hours have been considered. Subjects were not exposed over such durations, but were instructed to estimate the overall comfort levels preferred had they been constantly subjected to vibration over such durations.

Jones, B.; Rao, B. K. N.

1975-01-01

180

Dual-Mode TimeSharing Cascaded Sinusoidal Inverter  

Microsoft Academic Search

This paper presents a novel dual-mode time-sharing cascaded sinusoidal inverter. It is composed of a time-sharing buck-type current-fed converter and time-sharing sinusoidal pulse-modulated full-bridge inverter. Compared with the conventional time-sharing cascaded sinusoidal inverter, it has higher power density and better control character.

Weimin Wu; Tianhao Tang

2007-01-01

181

Attenuation of intense sinusoidal waves in air-saturated, bulk porous materials  

NASA Technical Reports Server (NTRS)

As intense, initially sinusoidal waves propagate in fluids, shocks form and excess attenuation of the wave occurs. Data are presented indicating that shock formation is not necessary for the occurrence of excess attenuation in nonlinear, lossy media, i.e., air-saturated, porous materials. An empirical equation is used to describe the excess attenuation of intense sinusoids in porous materials. The acoustic nonlinearity of and the excess attenuation in porous materials may be predicted directly from dc flow resistivity data. An empirical relationship is used to relate an acoustic nonlinearity parameter to the fundamental frequency and relative dc nonlinearity of two structurally different materials.

Kuntz, Herbert L.; Blackstock, David T.

1987-01-01

182

Reduction of low frequency magnetic noise by voltage-induced magnetic anisotropy modulation in tunneling magnetoresistance sensors  

NASA Astrophysics Data System (ADS)

We demonstrate the reduction and control of magnetic noise by voltage-induced perpendicular anisotropy modulation in CoFeB/MgO/CoFeB sensors. The noise decreases with the increase of the perpendicular anisotropy energy induced by the bias voltage polarity reversal. The bias reversal between -1 and +1 V results in a reduction of the normalized 1/f magnetic noise parameters by a factor of 7.3 and the thermal magnetic noise by a factor of 6.8. In the state of the highest field sensitivity, the lowest normalized 1/f magnetic noise parameter reaches 6.45 × 10-14 ?m3T. The results indicate that voltage-induced anisotropy modulation can be used to control and suppress magnetization fluctuations in the sensing layer and thus, significantly reduce the magnetic noise.

Wisniowski, P.; D?bek, M.; Skowronski, W.; Stobiecki, T.; Cardoso, S.; Freitas, P. P.

2014-08-01

183

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

184

Response of primate cones to sinusoidally flickering homochromatic stimuli.  

PubMed Central

1. The response of the primate cone photoreceptors to sinusoidally flickering stimuli has been obtained by monitoring the late receptor potential (LRP). 2. By comparing the response characteristics of the foveal local electroretinogram (LERG) before and after the intraocular infusion of sodium aspartate, it was found that the b-wave in the foveal LERG does not affect the monitoring of the LRP to steady-state flicker. 3. Functions describing the supra-threshold frequency response characteristics of the photoreceptors were obtained. 4. Linearity was found to hold for low amplitude responses, and temporal modulation transfer functions (MTFs) were obtained for the photoreceptors at various adaptation levels. 5. The cone photoreceptors were found to act approximately as passive low pass filters compounded with some low frequency attenuation. 6. The high frequency response of the photoreceptors at various adaptation levels tends toward a common high frequency asymptote, much like human psychophysical findings, and can be described by a diffusion model. 7. Non-linearities (convexity-upwards) suggest modest positive feedback at the level of the photoreceptors. 8. Mechanisms limiting the magnitude of the receptor response at low frequencies have little effect on the phase lag of the response. PMID:1142248

Baron, W S; Boynton, R M

1975-01-01

185

1072 JOURNAL OF MICROELECTROMECHANICAL SYSTEMS, VOL. 17, NO. 5, OCTOBER 2008 Voltage Control of the Resonance Frequency of  

E-print Network

on the characterization, active tuning, and modeling of the first mode resonance frequency of dielectric electroactive. A reduction in resonance frequency up to 77% (limited by dielectric breakdown) from the initial value of 1620 of the Resonance Frequency of Dielectric Electroactive Polymer (DEAP) Membranes Philippe Dubois, Samuel Rosset

Floreano, Dario

186

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

1994-01-01

187

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

188

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

E-print Network

REVIEW OF SCIENTIFIC INSTRUMENTS 82, 086113 (2011) Note: Piezoelectric strain voltage sensing tool for measurement of various quantities such as pressure, acceleration, strain, or force across many be interfaced with an external device that would typically have a finite input impedance. This, together

Moheimani, Reza

2011-01-01

189

Robust rejection of sinusoids in stable nonlinearly perturbed unmodelled linear systems: Theory and application to servo  

Microsoft Academic Search

? Abstract—Assuming no knowledge of closed-loop dynamics other than being that of a stable nonlinearly perturbed linear system and the forward path gain at the frequency of interest being known and non-zero, a control approach is proposed that rejects a sinusoidal disturbance of known frequency from the system output. The approach consists in partitioning the feedback path of a stable

Vivek Natarajan; Joseph Bentsman

2011-01-01

190

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  

E-print Network

-constructed regression models that allow the CPU to calculate the expected workload and slack time for the next time slot, and thus, adjust its voltage and frequency in order to save energy while meeting soft timing constraints

Pedram, Massoud

191

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.

Andrzej Sokolowski

192

Isothermal sinusoidal analysis of balanced compound Vuilleumier heat pumps  

NASA Astrophysics Data System (ADS)

A previously published more rigorous analysis of integrated Vuilleumier heat pumps with balanced compounding is simplified. The present procedure is based on previously demonstrated sinusoidal excursions of the reciprocators. It is of the same order of accuracy, but much simpler and more usable. It was found that there is only a negligible difference between the two approaches. The present treatment is also applicable to kinematic as well as to free-piston machines. For the latter design, an equation for the natural frequency is also derived. Ideal proportions and practical expressions for the energy streams are derived. Gas forces are plotted vs displacement, and it is shown that they are equivalent to a linear spring, which is of importance for the concept of a free-piston design.

Finkelstein, Theodor

193

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

194

Steady-state sinusoidal behavior of elastomeric dampers  

NASA Astrophysics Data System (ADS)

This paper presents an experimental and analytical investigation of an elastomeric damping material and assesses its potential application to stability augmentation of hingeless and bearingless helicopter rotors. Double lap shear specimens were tested on a servo-hydraulic testing machine. Single frequency sinusoidal tests were conducted over a strain amplitude range of 0 - 30% at three frequencies (lag/rev, 1/rev and a lower harmonic of the rotor). The frequencies were chosen such that the effect of the damper in mitigating instability phenomena, like ground and air resonance, could be analyzed. The effects of frequency, amplitude, pre-load and material self-heating were studied. A three-element mechanisms-based damper model was developed that accurately captures the energy dissipation and hysteresis behavior of the damper. The model incorporates a linear stiffness, viscous damping and a non-linear slip element that are placed in parallel to each other. The parameters of the model were identified using an LMS technique. The model was validated by reconstructing measured hysteresis cycles using these parameters.

Madhavan, Vijay; Wereley, Norman M.; Sieg, Thierry

1999-06-01

195

Interplay between low threshold voltage-gated K+ channels and synaptic inhibition in neurons of the chicken nucleus laminaris along its frequency axis  

PubMed Central

Central auditory neurons that localize sound in horizontal space have specialized intrinsic and synaptic cellular mechanisms to tightly control the threshold and timing for action potential generation. However, the critical interplay between intrinsic voltage-gated conductances and extrinsic synaptic conductances in determining neuronal output are not well understood. In chicken, neurons in the nucleus laminaris (NL) encode sound location using interaural time difference (ITD) as a cue. Along the tonotopic axis of NL, there exist robust differences among low, middle, and high frequency (LF, MF, and HF, respectively) neurons in a variety of neuronal properties such as low threshold voltage-gated K+ (LTK) channels and depolarizing inhibition. This establishes NL as an ideal model to examine the interactions between LTK currents and synaptic inhibition across the tonotopic axis. Using whole-cell patch clamp recordings prepared from chicken embryos (E17–E18), we found that LTK currents were larger in MF and HF neurons than in LF neurons. Kinetic analysis revealed that LTK currents in MF neurons activated at lower voltages than in LF and HF neurons, whereas the inactivation of the currents was similar across the tonotopic axis. Surprisingly, blockade of LTK currents using dendrotoxin-I (DTX) tended to broaden the duration and increase the amplitude of the depolarizing inhibitory postsynaptic potentials (IPSPs) in NL neurons without dependence on coding frequency regions. Analyses of the effects of DTX on inhibitory postsynaptic currents led us to interpret this unexpected observation as a result of primarily postsynaptic effects of LTK currents on MF and HF neurons, and combined presynaptic and postsynaptic effects in LF neurons. Furthermore, DTX transferred subthreshold IPSPs to spikes. Taken together, the results suggest a critical role for LTK currents in regulating inhibitory synaptic strength in ITD-coding neurons at various frequencies. PMID:24904297

Hamlet, William R.; Liu, Yu-Wei; Tang, Zheng-Quan; Lu, Yong

2014-01-01

196

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] [Memorial Univ. of Newfoundland, St. Johns, Newfoundland (Canada). Faculty of Engineering and Applied Science

1996-07-01

197

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

NASA Technical Reports Server (NTRS)

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

Gabriel, G. J.

1977-01-01

198

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

199

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

200

Modulation rate discrimination using half-wave rectified and sinusoidally amplitude modulated stimuli in cochlear-implant users  

PubMed Central

Detection and modulation rate discrimination were measured in cochlear-implant users for pulse-trains that were either sinusoidally amplitude modulated or were modulated with half-wave rectified sinusoids, which in acoustic hearing have been used to simulate the response to low-frequency temporal fine structure. In contrast to comparable results from acoustic hearing, modulation rate discrimination was not statistically different for the two stimulus types. The results suggest that, in contrast to binaural perception, pitch perception in cochlear-implant users does not benefit from using stimuli designed to more closely simulate the cochlear response to low-frequency pure tones. PMID:20136187

Kreft, Heather A.; Oxenham, Andrew J.; Nelson, David A.

2010-01-01

201

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

NASA Astrophysics Data System (ADS)

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

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

2015-06-01

202

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

NASA Technical Reports Server (NTRS)

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

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

1965-01-01

203

Simultaneous powerline interference and baseline wander removal from ECG and EMG signals by sinusoidal modeling.  

PubMed

We present a compact approach to joint modeling of powerline interference (PLI) and baseline wonder (BW) for denoising of biopotential signals. Both PLI and BW are modeled by a set of harmonically related sinusoids modulated by low-order time polynomials. The sinusoids account on the harmonicity and mean instantaneous frequency of the PLI in the analysis window, while the polynomials capture the frequency and amplitude deviations from their nominal values and characterize the BW at the same time. The resulting model is linear-in-parameters and the solution to the corresponding linear system is estimated in a simple and efficient way through linear least-squares. The proposed modeling method was evaluated on real electrocardiographic (ECG) and electromyographic (EMG) signals against three reference methods for different analysis scenarios. The comparative study suggests that the proposed method outperforms the reference methods in terms of residual interference energy in the denoised biopotential signals. PMID:23608299

Zivanovic, Miroslav; González-Izal, Miriam

2013-10-01

204

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

E-print Network

heating directly in the ice. In addition, skin effect causes current to flow only in a thin layer on the surface of the line, causing resistive losses and consequent heating. In this article, we describe. Achieving Uniform Heating Exciting a transmission line with high-frequency power will produce standing waves

205

Low Actuation Voltage RF MEMS SwitchesWith Signal Frequencies From 0.25GHz to 40GHz  

E-print Network

(b), the conductive pad is attracted upward. RF signals flow through the output port without much insertion loss characteristics over a wide frequency range make MEMS switches the most attractive devices for reconfigurable signal from one port will short to the ground and no RF signal will flow through the other port

Shen, Shyh-Chiang

206

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

E-print Network

applications, such as millimeter-wave mixer design, the nonlinear capacitance affects the mixing performance capacitance of a weakly nonlinear device at microwave and millimeter wave frequencies. Unlike other approaches. In microwave or millimeter-wave system design, nonlinear simulation and modeling forms a critically important

Haddadi, Hamed

207

Calculation of the mean path length of the Epstein frame under non-sinusoidal excitations using the double Epstein method  

NASA Astrophysics Data System (ADS)

This paper discusses the effect of non-sinusoidal excitation on the mean path length of the Epstein frame. Two different steels, a non-oriented (NO) steel and a high-permeability grain-oriented (HGO) electrical steel have been tested under pure sinusoidal and non-sinusoidal excitations and the mean path length of the Epstein frame has been re-calculated. Results indicate that the actual mean path of the Epstein frame depends not only on the material permeability and anisotropy but also on the peak flux density and magnetising frequency. The amount of distortion of the excitation frequency also has an effect on the value of the actual mean path length of the Epstein frame.

Marketos, Philip; Zurek, Stan; Moses, Anthony J.

208

Estimating the number of sinusoids in additive white noise  

Microsoft Academic Search

The test proposed uses the eigenvector decomposition of the estimated autocorrelation matrix and is based on matrix perturbation analysis. The estimator is shown to be able to resolve closely spaced sinusoids at lower signal-to-noise ratios than heuristic tests. Simulation results for two closely spaced sinusoids are detailed. Several unanswered questions are discussed

JEAN-JACQUES FUCHS

1988-01-01

209

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

NASA Astrophysics Data System (ADS)

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

Kalyanraj, D.; Lenin Prakash, S.

2014-01-01

210

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

NASA Astrophysics Data System (ADS)

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

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

2008-08-01

211

Extraction of the sub-bandgap density-of-states in polymer thin-film transistors with the multi-frequency capacitance-voltage spectroscopy  

NASA Astrophysics Data System (ADS)

The multi-frequency capacitance-voltage (C-V) spectroscopy is proposed for extracting the sub-bandgap density-of-states (DOS) of polymer semiconductors and demonstrated in three different thiophene-based organic thin-film transistors including poly(3-hexylthiophene), poly(3,3'''-didodecylquaterthiophene), and poly(didodecylquaterthiophene-alt-didodecylbithiazole). The density of exponential tail and exponential deep states are extracted to be in the range of 3.0 × 1018 ˜ 1.5 × 1019 cm-3 eV-1 and 3.0 × 1016 ˜ 3.0 × 1017 cm-3 eV-1, respectively. The extracted DOS correspond to the polymer semiconductor-dependence of the measured crystallinity and mobility. In addition, the extracted DOS values are verified by comparing the measured I-V characteristics with the simulated results through a technology computer-aided design tool.

Jang, Jaeman; Kim, Jaehyeong; Bae, Minkyung; Lee, Jaewook; Myong Kim, Dong; Hwan Kim, Dae; Lee, Jiyoul; Lee, Bang-Lin; Koo, Bonwon; Wan Jin, Yong

2012-03-01

212

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

SciTech Connect

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

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

2013-11-15

213

Coherent Voltage Oscillations in Superconducting Polycrystalline Y1Ba2Cu3O7-x  

NASA Astrophysics Data System (ADS)

We have investigated the voltage response of superconducting polycrystalline bulk Y1Ba2Cu3O7-x (YBCO) material to a bidirectional square wave current with long periods and dc current by means of the evolution of the voltage-time (V-t) curves near the critical temperature. In a well-defined range of amplitudes and periods of driving current, and temperatures, it was observed that a non-linear response to bidirectional square wave current rides on a time independent background voltage value and manifests itself as regular sinusoidal-like voltage oscillations. It was found that the non-linear response disappears when the bidirectional current was switched to dc current. The spectral content of the voltage oscillations analyzed by the Fast Fourier Transform of the corresponding V-t curves revealed that the fundamental harmonics is comparable to the frequency of bidirectional square wave current. The coherent voltage oscillations were discussed mainly in terms of the dynamic competition between pinning and depinning together with the disorder in the coupling strength between the superconducting grains (i.e Josephson coupling effects). The density fluctuations and semi-elastic coupling of the flux lines with the pinning centers were also considered as possible physical mechanisms in the interpretation of the experimental results.

Altinkok, A.; Yeti?, H.; Oluta?, M.; Kiliç, K.; Kiliç, A.; Çetin, O.

2006-06-01

214

LINEAR FIBROBLAST ALIGNMENT ON SINUSOIDAL WAVE MICROPATTERNS  

PubMed Central

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 hours after cell seeding. Attachment strength was studied via subjecting cells on substrates to centrifugal force following a 24-hour 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

2013-01-01

215

Frequency Domain Controller Design 9.2 Frequency Response Characteristics  

E-print Network

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

Gajic, Zoran

216

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

NASA Technical Reports Server (NTRS)

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

Richmond, J. H.

1974-01-01

217

780W narrow linewidth all fiber laser with sinusoidal phase modulation  

NASA Astrophysics Data System (ADS)

In high power fiber laser, the limiting factor of narrow linewidth output is analyzed. The influence of Stimulated Brillouin scattering effect and sinusoidal phase modulation suppressing method are studied. The linewidth of a single frequency laser is broadened from 1MHz to 2.9 GHz by sinusoidal phase modulation technology. The output power of single frequency laser is 50mW. And through three stage fiber amplified, the central wavelength of 1064.34nm, linewidth of 2.9 GHz and power of 780W are achieved respectively. The optical-optical efficiency is 79%. And the beam quality is [see manuscript] and [see manuscript]. The distributing characteristic of longitudinal mode, under every modulating coefficient, is measured. And the result is the same as theoretical result. The increasing of longitudinal mode number, controlling of longitudinal mode spacing and reducing power spectrum density by sinusoidal phase modulation are proved to be viable. Then Stimulated Brillouin Scattering threshold is increased. Finally, the output power is increased a lot. The output power of this laser is only limited by pump power. If the pump power is increased, the higher power of narrow linewidth fiber laser will be achieved.

Zhang, Liming; Zhou, Shouhuan; Zhao, Hong; Zhang, Kun; Hao, Jinping; Zhang, Dayong; Zhu, Chen; Li, Yao; Wang, Xiongfei; Chen, Nianjiang

2014-11-01

218

A nonlinear global model of a dual frequency capacitive discharge  

SciTech Connect

The behavior of dual frequency capacitively coupled plasmas is investigated. Assuming a realistic reactor configuration represented by effective geometry factors and taking into account two separate sinusoidal voltage sources operating at different frequencies, an ordinary differential equation is derived which describes the nonlinear dynamics of such discharges. An exact analytical solution of the equation is presented and employed for a parameter study of the discharge current characteristics. Simulation results for various gas pressures (=various electron-neutral collision rates), various amplitude ratios of the two independent rf sources, and various integer frequency ratios are shown. When the two frequencies are comparable, surprising nonlinear effects are observed. Particular under study is the heating at the plasma series resonance, either by direct excitation or via the nonlinear electron resonance heating mechanism.

Mussenbrock, Thomas; Ziegler, Dennis; Peter Brinkmann, Ralf [Ruhr University Bochum, Center for Plasma Science and Technology, Institute for Theoretical Electrical Engineering, D-44780 Bochum (Germany)

2006-08-15

219

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

NASA Technical Reports Server (NTRS)

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

Lipo, Thomas A.; Alan, Irfan

1991-01-01

220

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

NASA Astrophysics Data System (ADS)

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

Lipo, Thomas A.; Alan, Irfan

1991-06-01

221

Microenvironmental regulation of the sinusoidal endothelial cell phenotype in vitro  

E-print Network

Liver sinusoidal endothelial cells (LSECs) differ, both structurally and functionally, from endothelial cells (ECs) lining blood vessels of other tissues. For example, in contrast to other ECs, LSECs possess fenestrations, ...

March, Sandra

222

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

NASA Technical Reports Server (NTRS)

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

Balla, R. Jeffrey; Miller, Corey A.

2008-01-01

223

Lymphocyte traffic through sinusoidal endothelial cells is regulated by hepatocytes.  

PubMed

Crosstalk between hepatic sinusoidal ECs and closely juxtaposed hepatocytes via vascular endothelial growth factor is essential for the maintenance of sinusoidal endothelial growth and differentiation. We propose that paracrine interactions between endothelial cells and hepatocytes also may be responsible for the unique complement of adhesion receptors expressed on sinusoidal endothelium that regulate the recruitment of lymphocytes into the liver. To address this hypothesis, we developed an in vitro model of the hepatic sinusoid in which flowing lymphocytes could interact with hepatic endothelium conditioned by the presence of hepatocytes. Human hepatic sinusoidal endothelial cells cocultured with hepatocytes were activated so that they supported the adhesion of lymphocytes at levels equivalent to those seen on endothelium stimulated with the inflammatory cytokine tumour necrosis factor-beta. Lymphocyte adhesion was supported by intracellular adhesion molecule 1, vascular cell adhesion molecule 1, and E-selectin, with an additional contribution from the novel adhesion receptor VAP-1. In conclusion, we show that interactions between hepatocytes and endothelial cells amplify leukocyte recruitment through the sinusoids by regulating the expression and function of endothelial adhesion molecules. These paracrine interactions may be responsible for the induction of the adhesion molecules that support constitutive lymphocyte recruitment to the liver as well as contributing significantly to the patterns of leukocyte adhesion seen during episodes of hepatic inflammation. PMID:15723297

Edwards, Sarah; Lalor, Patricia F; Nash, Gerard B; Rainger, G Ed; Adams, David H

2005-03-01

224

High-Voltage, Asymmetric-Waveform Generator  

NASA Technical Reports Server (NTRS)

The shapes of waveforms generated by commercially available analytical separation devices, such as some types of mass spectrometers and differential mobility spectrometers are, in general, inadequate and result in resolution degradation in output spectra. A waveform generator was designed that would be able to circumvent these shortcomings. It is capable of generating an asymmetric waveform, having a peak amplitude as large as 2 kV and frequency of several megahertz, which can be applied to a capacitive load. In the original intended application, the capacitive load would consist of the drift plates in a differential-mobility spectrometer. The main advantage to be gained by developing the proposed generator is that the shape of the waveform is made nearly optimum for various analytical devices requiring asymmetric-waveform such as differential-mobility spectrometers. In addition, this waveform generator could easily be adjusted to modify the waveform in accordance with changed operational requirements for differential-mobility spectrometers. The capacitive nature of the load is an important consideration in the design of the proposed waveform generator. For example, the design provision for shaping the output waveform is based partly on the principle that (1) the potential (V) on a capacitor is given by V=q/C, where C is the capacitance and q is the charge stored in the capacitor; and, hence (2) the rate of increase or decrease of the potential is similarly proportional to the charging or discharging current. The proposed waveform generator would comprise four functional blocks: a sine-wave generator, a buffer, a voltage shifter, and a high-voltage switch (see Figure 1). The sine-wave generator would include a pair of operational amplifiers in a feedback configuration, the parameters of which would be chosen to obtain a sinusoidal timing signal of the desired frequency. The buffer would introduce a slight delay (approximately equal to 20 ns) but would otherwise leave the fundamental timing signal unchanged. The buffered timing signal would be fed as input to the level shifter. The output of the level shifter would serve as a timing and control signal for the high-voltage switch, causing the switch to alternately be (1) opened, allowing the capacitive load to be charged from a high-voltage DC power supply; then (2) closed to discharge the capacitive load to ground. Hence, the output waveform would closely approximate a series of exponential charging and discharging curves (see Figure 2).

Beegle, Luther W.; Duong, Tuan A.; Duong, Vu A.; Kanik, Isik

2008-01-01

225

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. PMID:3779003

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

1986-01-01

226

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

NASA Astrophysics Data System (ADS)

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

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

2015-04-01

227

A surface profile reconstruction system using sinusoidal phase-modulating interferometry and fiber-optic fringe projection  

NASA Astrophysics Data System (ADS)

A fiber-optic sinusoidal phase modulating (SPM) interferometer for surface profile reconstruction is presented. Sinusoidal phase modulation is created by modulating the drive voltage of the piezoelectric transducer. The surface profile is constructed basing on fringe projection. Fringe patterns are vulnerable to external disturbances such as temperature fluctuation and mechanical vibration, which cause phase drift and decrease measuring accuracy. We build a closed-loop feedback phase compensation system, the bias value of external disturbances superimposed on fringe patterns can be reduced to about 50 mrad, and the phase stability for interference fringes is less than 5.76 mrad. By measuring the surface profile of a paper plate for two times, the repeatability is estimated to be about 11 nm, and is equivalent to be about ?/69. For a plane with 100 × 100 points, a single measurement takes less than 140 ms, and the feasibility for real-time profile measurement with high accuracy has been verified.

En, Bo; Fa-jie, Duan; Chang-rong, Lv; Fan, Feng; Xiao, Fu

2014-06-01

228

Time-dependent perturbation of a two-state quantum system by a sinusoidal field  

NASA Technical Reports Server (NTRS)

Different methods for solving the 'two-level problem' are discussed, namely, the problem of what happens to a material system having only two nondegenerate energy levels when it is perturbed by an electromagnetic field that varies with time in a monochromatic sinusoidal fashion. The various methods discussed include: (1) the Sen Gupta technique using nondegenerate Rayleigh-Schroedinger perturbation theory, (2) the Salwen-Winter-Shirley partitioning perturbation technique, (3) the Shirley and series degenerate Rayleigh-Schroedinger expansion, (4) the degenerate Rayleigh-Schroedinger technique for considering high frequency fields, and (5) the singular perturbation expansion technique.

Dion, D. R.; Hirschfelder, J. O.

1976-01-01

229

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

230

Bottomside sinusoidal irregularities in the equatorial F region  

NASA Technical Reports Server (NTRS)

By using the Ogo 6 satellite, McClure and Hanson (1973) have discovered sinusoidal irregularities in the equatorial F region ion number density. In the present investigation, a description is provided of the properties of a distinct category of sinusoidal irregularities found in equatorial data from the AE-C and AE-E satellites. The observed scale sizes vary from about 300 m to 3 km in the direction perpendicular to B, overlapping with and extending the range observed by using Ogo 6. Attention is given to low and high resolution data, a comparison with Huancayo ionograms, the confinement of 'bottomside sinusoidal' (BSS) irregularities essentially to the bottomside of the F layer, spectral characteristics, and BSS, scintillation, and ionosonde observations.

Valladares, C. E.; Hanson, W. B.; Mcclure, J. P.; Cragin, B. L.

1983-01-01

231

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.

232

An automated system for measuring parameters of nematode sinusoidal movement  

PubMed Central

Background Nematode sinusoidal movement has been used as a phenotype in many studies of C. elegans development, behavior and physiology. A thorough understanding of the ways in which genes control these aspects of biology depends, in part, on the accuracy of phenotypic analysis. While worms that move poorly are relatively easy to describe, description of hyperactive movement and movement modulation presents more of a challenge. An enhanced capability to analyze all the complexities of nematode movement will thus help our understanding of how genes control behavior. Results We have developed a user-friendly system to analyze nematode movement in an automated and quantitative manner. In this system nematodes are automatically recognized and a computer-controlled microscope stage ensures that the nematode is kept within the camera field of view while video images from the camera are stored on videotape. In a second step, the images from the videotapes are processed to recognize the worm and to extract its changing position and posture over time. From this information, a variety of movement parameters are calculated. These parameters include the velocity of the worm's centroid, the velocity of the worm along its track, the extent and frequency of body bending, the amplitude and wavelength of the sinusoidal movement, and the propagation of the contraction wave along the body. The length of the worm is also determined and used to normalize the amplitude and wavelength measurements. To demonstrate the utility of this system, we report here a comparison of movement parameters for a small set of mutants affecting the Go/Gq mediated signaling network that controls acetylcholine release at the neuromuscular junction. The system allows comparison of distinct genotypes that affect movement similarly (activation of Gq-alpha versus loss of Go-alpha function), as well as of different mutant alleles at a single locus (null and dominant negative alleles of the goa-1 gene, which encodes Go-alpha). We also demonstrate the use of this system for analyzing the effects of toxic agents. Concentration-response curves for the toxicants arsenite and aldicarb, both of which affect motility, were determined for wild-type and several mutant strains, identifying P-glycoprotein mutants as not significantly more sensitive to either compound, while cat-4 mutants are more sensitive to arsenite but not aldicarb. Conclusions Automated analysis of nematode movement facilitates a broad spectrum of experiments. Detailed genetic analysis of multiple alleles and of distinct genes in a regulatory network is now possible. These studies will facilitate quantitative modeling of C. elegans movement, as well as a comparison of gene function. Concentration-response curves will allow rigorous analysis of toxic agents as well as of pharmacological agents. This type of system thus represents a powerful analytical tool that can be readily coupled with the molecular genetics of nematodes. PMID:15698479

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

2005-01-01

233

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

NASA Technical Reports Server (NTRS)

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

Robinson, R. E.

1972-01-01

234

Low Voltage Power Supply Incorporating Ceramic Transformer  

E-print Network

A low voltage power supply provides the regulated output voltage of 1 V from the supply voltage around 48 V. The low voltage power supply incorporates a ceramic transformer which utilizes piezoelectric effect to convert voltage. The ceramic transformer isolates the secondary from the primary, thus providing the ground isolation between the supply and the output voltages. The ceramic transformer takes the place of the conventional magnetic transformer. The ceramic transformer is constructed from a ceramic bar and does not include any magnetic material. So the low voltage power supply can operate under a magnetic field. The output voltage is stabilized by feedback. A feedback loop consists of an error amplifier, a voltage controlled oscillator and a driver circuit. The amplitude ratio of the transformer has dependence on the frequency, which is utilized to stabilize the output voltage. The low voltage power supply is investigated on the analogy of the high voltage power supply similarly incorporating the cerami...

Imori, M

2007-01-01

235

Frequency of collisions between ion and neutral particles from the cloning characteristics of filamentary currents in an atmospheric pressure helium plasma jet  

NASA Astrophysics Data System (ADS)

In this paper, a cold He atmospheric pressure plasma jet that is generated using a dielectric barrier discharge configuration device is presented. This device is equipped with double-grounded ring electrodes that are driven by a sinusoidal excitation voltage. The properties of the cloning of filamentous current are studied. The frequency of the collisions between the ion and the neutral particles is calculated by measuring the current phase difference between the filamentous current and its corresponding clone. The frequency of the collisions between the ion and the neutral particles is of the order of 108 Hz.

Qi, Bing; Zhang, Mengdie; Pan, Lizhu; Zhou, Qiujiao; Huang, Jianjun; Liu, Ying

2015-02-01

236

A performance-enhanced energy harvester for low frequency vibration utilizing a corrugated cantilevered beam  

NASA Astrophysics Data System (ADS)

This note proposes a performance-enhanced piezoelectric energy harvester by replacing a conventional flat cantilevered beam with a corrugated beam. It consists of a proof mass and a sinusoidally or trapezoidally corrugated cantilevered beam covered by a polyvinylidene fluoride (PVDF) film. Compared to the conventional energy harvester of the same size, it has a more flexible bending stiffness and a larger bonding area of the PVDF layer, so higher output voltage from the device can be expected. In order to investigate the characteristics of the proposed energy harvester, analytical developments and numerical simulations on its natural frequency and tip displacement are carried out. Shaking table tests are also conducted to verify the performance of the proposed device. It is clearly shown from the tests that the proposed energy harvester not only has a lower natural frequency than an equivalent sized standard energy harvester, but also generates much higher output voltage than the standard one.

Kim, In-Ho; Jin, SeungSeop; Jang, Seon-Jun; Jung, Hyung-Jo

2014-03-01

237

A robust sinusoidal signal processing method for interferometers  

NASA Astrophysics Data System (ADS)

Laser interferometers are widely used as a reference for length measurement. Reliable bidirectional optical fringe counting is normally obtained by using two orthogonally sinusoidal signals derived from the two outputs of an interferometer with path difference. These signals are subject to be disturbed by the geometrical errors of the moving target that causes the separation and shift of two interfering light spots on the detector. It results in typical Heydemann errors, including DC drift, amplitude variation and out-of-orthogonality of two sinusoidal signals that will seriously reduce the accuracy of fringe counting. This paper presents a robust sinusoidal signal processing method to correct the distorted waveforms by hardware. A corresponding circuit board has been designed. A linear stage equipped with a laser displacement interferometer and a height gauge equipped with a linear grating interferometer are used as the test beds. Experimental results show that, even with a seriously disturbed input waveform, the output Lissajous circle can always be stabilized after signal correction. This robust method increases the stability and reliability of the sinusoidal signals for data acquisition device to deal with pulse count and phase subdivision.

Wu, Xiang-long; Zhang, Hui; Tseng, Yang-Yu; Fan, Kuang-Chao

2013-10-01

238

Sound waves in two-dimensional ducts with sinusoidal walls  

NASA Technical Reports Server (NTRS)

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

Nayfeh, A. H.

1974-01-01

239

A model selection rule for sinusoids in white Gaussian noise  

Microsoft Academic Search

The model selection problem for sinusoidal signals has often been addressed by employing the Akaike (1974) information criterion (AIC) and the minimum description length principle (MDL). The popularity of these criteria partly stems from the intrinsically simple means by which they can be implemented. They can, however, produce misleading results if they are not carefully used. The AIC and MDL

Petar M. DjuriC

1996-01-01

240

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

241

Estimating Sinusoidal Pressure Waves In A Pump Volute  

NASA Technical Reports Server (NTRS)

Closed-form equation approximates principal traveling-wave sinusoidal components of fluctuations of pressure in volute of centrifugal pump. Equation incorporated into Blade Vane Interaction Code (BVIC) computer program, which produces estimates for various pump speeds and various locations in volute. Intended use of BVIC in analysis of undesired interactions between pressure field and pump structure.

Szabo, Roland J.; Chon, Juliet T.

1994-01-01

242

Speech enhancement using a constrained iterative sinusoidal model  

Microsoft Academic Search

This paper presents a sinusoidal model based algorithm for enhancement of speech degraded by additive broad-band noise. In order to ensure speech-like characteristics observed in clean speech, smoothness constraints are imposed on the model parameters using a spectral envelope surface (SES) smoothing procedure. Algorithm evaluation is performed using speech signals degraded by additive white Gaussian noise. Distortion as measured by

Jesper Jensen; John H. L. Hansen

2001-01-01

243

Detection of multiple sinusoids using a parallel ale  

SciTech Connect

This paper introduces an Adaptive Line Enhancer (ALE) whose parallel structure enables the detection and enhancement of multiple sinusoids. A function describing the performance surface is derived for the case where several line signals are buried in white noise. A steepest descent adaptive algorithm is derived, and simulations are used to demonstrate its performance.

David, R.A.

1984-01-01

244

Variants of rectifiers with near sinusoidal input currents  

Microsoft Academic Search

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

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

2011-01-01

245

G-seat system step input and sinusoidal response characteristics  

NASA Technical Reports Server (NTRS)

The step input and sinusoidal response characteristics of a pneumatically driven computer controlled G set are examined in this study. The response data show that this system can be modeled as a first order system with an 0.08 sec time lag and a 0.53 sec time constant.

Showalter, T. W.; Miller, R. J.

1978-01-01

246

New variable speed drive with proven motor friendly performance for medium voltage motors  

Microsoft Academic Search

A medium voltage VSD is described, where existing standard motors can be connected. The sinusoidal quality of its output voltage is proven by AC machine manufacturer tests. No additional motor losses exist compared to operation direct on line. For quadratic loads like pumps and fans, self-ventilated motors can be operated at variable speed without cooling problems. This paper describes a

Juergen K. Steinke; Risto Vuolle; Herbert Prenner; J. Jarvinen

1999-01-01

247

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.

248

Effect of Substrate Bias Voltage on the Physical Properties of Zirconium Nitride (ZrN) Films Deposited by Mid Frequency Reactive Magnetron Sputtering  

NASA Astrophysics Data System (ADS)

Present work involves the preparation of Zirconium Nitride thin films on stainless steel (SS) (304L grade) substrate by reactive cylindrical magnetron sputtering method. The X-ray diffraction (XRD) profile of the ZrN thin films prepared with different bias voltage conforms face centered cubic structure with preferred orientation along the (111) plane at lower bias voltage (100 V) and at higher bias voltage (300 V) the preferred orientation shifted to (220) plane. The influences of bias voltage on the thickness and microhardness ZrN thin films have been studied. ZrN thin film sputtered with 300 V bias voltage shows the maximum reflectance of 90% at a wavelength of 1000 nm. The coated substrates have been found to exhibit improved corrosion resistance compared to the SS plate. The root mean square surface roughness and surface morphology were investigated from 3D atomic force microscope (AFM) images and scanning electron microscope (SEM), which indicate smooth and uniform surface pattern without any pin holes.

Kavitha, A.; Kannan, R.; Loganathan, S.

2014-05-01

249

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

PubMed Central

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

Chen, Hongtao

2013-01-01

250

Chronic high-frequency repetitive transcranial magnetic stimulation improves age-related cognitive impairment in parallel with alterations in neuronal excitability and the voltage-dependent Ca(2+) current in female mice.  

PubMed

Chronic high-frequency repetitive transcranial magnetic stimulation (rTMS) is a noninvasive method to increase the excitability of neurons, and it induces long-term effects that can improve symptoms related to neurodegenerative diseases, including cognitive ability. The present study was undertaken to identify the mechanism by which rTMS improves cognitive impairments in mice. The novel object recognition test in vivo was used to evaluate the cognitive function of the mice. Whole-cell patch-clamp recordings were used to evaluate the neuronal excitability, including the resting membrane potential, the number of action potentials induced by depolarized current, after-hyperpolarization, and the voltage-dependent Ca(2+) current in hippocampal slices. We found that the aged mice showed impairments in cognitive function, and high-frequency (25Hz) rTMS for 14 consecutive-days ameliorated the impairments. Whole-cell patch-clamp recordings showed that, compared to matured mice, the hippocampal CA1 pyramidal neurons of aged mice showed significantly hyperpolarized resting membrane potential, significantly decreased numbers of action potentials after injection of depolarizing current, and significantly increased after-hyperpolarization after an action potential. The exposure to high-frequency rTMS significantly improved the above deficits in the neuronal excitability in the aged rTMS mice. Consistent with the above changes, the exposure to high-frequency rTMS also significantly decreased the voltage-dependent Ca(2+) current of the neurons compared with the aged sham mice. These data suggested that the rTMS could improve the age-related cognitive impairment in parallel with regulating the neuronal excitability and modifying the voltage-dependent Ca(2+) channels. PMID:25451310

Wang, Hua-Long; Xian, Xiao-Hui; Wang, Yan-Yong; Geng, Yuan; Han, Bing; Wang, Ming-Wei; Li, Wen-Bin

2015-02-01

251

Frequency of subthreshold oscillations at different membrane potential voltages in neurons at different anatomical positions on the dorsoventral axis in the rat medial entorhinal cortex.  

PubMed

Neurons from layer II of the medial entorhinal cortex show subthreshold membrane potential oscillations (SMPOs) which could contribute to theta-rhythm generation in the entorhinal cortex and to generation of grid cell firing patterns. However, it is unclear whether single neurons have a fixed unique oscillation frequency or whether their frequency varies depending on the mean membrane potential in a cell. We therefore examined the frequency of SMPOs at different membrane potentials in layer II stellate-like cells of the rat medial entorhinal cortex in vitro. Using whole-cell patch recordings, we found that the fluctuations in membrane potential show a broad band of low power frequencies near resting potential that transition to more narrowband oscillation frequencies with depolarization. The transition from broadband to narrowband frequencies depends on the location of the neuron along the dorsoventral axis in the entorhinal cortex, with dorsal neurons transitioning to higher-frequency oscillations relative to ventral neurons transitioning to lower-frequency oscillations. Once SMPOs showed a narrowband frequency, systematic frequency changes were not observed with further depolarization. Using a Hodgkin-Huxley-style model of membrane currents, we show that differences in the influence of depolarization on the frequency of SMPOs at different dorsal to ventral positions could arise from differences in the properties of the h current. The properties of frequency changes in this data are important for evaluating models of the generation of grid cell firing fields with different spacings along the dorsal-to-ventral axis of medial entorhinal cortex. PMID:21880929

Yoshida, Motoharu; Giocomo, Lisa M; Boardman, Ian; Hasselmo, Michael E

2011-08-31

252

Sinusoidal phase modulation as a gate for FROG N. K. Fontaine, R. P. Scott, J. P. Heritage, B. H. Kolner, and S. J. B. Yoo  

E-print Network

Sinusoidal phase modulation as a gate for FROG N. K. Fontaine, R. P. Scott, J. P. Heritage, B. H-correlation frequency-resolved optical gating (PM- FROG) is demonstrated. This low-loss, linear gating technique can be used without separate gate characteri- zation via a blind FROG algorithm with a simple intensity

Kolner, Brian H.

253

Normal seasonal variations for atmospheric radon concentration: a sinusoidal model.  

PubMed

Anomalous radon readings in air have been reported before an earthquake activity. However, careful measurements of atmospheric radon concentrations during a normal period are required to identify anomalous variations in a precursor period. In this study, we obtained radon concentration data for 5 years (2003-2007) that can be considered a normal period and compared it with data from the precursory period of 2008 until March 2011, when the 2011 Tohoku-Oki Earthquake occurred. Then, we established a model for seasonal variation by fitting a sinusoidal model to the radon concentration data during the normal period, considering that the seasonal variation was affected by atmospheric turbulence. By determining the amplitude in the sinusoidal model, the normal variation of the radon concentration can be estimated. Thus, the results of this method can be applied to identify anomalous radon variations before an earthquake. PMID:25464051

Hayashi, Koseki; Yasuoka, Yumi; Nagahama, Hiroyuki; Muto, Jun; Ishikawa, Tetsuo; Omori, Yasutaka; Suzuki, Toshiyuki; Homma, Yoshimi; Mukai, Takahiro

2015-01-01

254

Evolution of statistical properties for a nonlinearly propagating sinusoid.  

PubMed

The nonlinear propagation of a pure sinusoid is considered using time domain statistics. The probability density function, standard deviation, skewness, kurtosis, and crest factor are computed for both the amplitude and amplitude time derivatives as a function of distance. The amplitude statistics vary only in the postshock realm, while the amplitude derivative statistics vary rapidly in the preshock realm. The statistical analysis also suggests that the sawtooth onset distance can be considered to be earlier than previously realized. PMID:21786869

Shepherd, Micah R; Gee, Kent L; Hanford, Amanda D

2011-07-01

255

Adaptive enhancement of multiple sinusoids in uncorrelated noise  

Microsoft Academic Search

The steady-state behavior of the adaptive line enhancer (ALE), a new implementation of adaptive filtering that has application in detecting and tracking narrow-band signals in broad-band noise, is analyzed for a stationary input consisting of multiple sinusoids in white noise. It is shown that the steady-state performance of an L-weight ALE for this case can be modeled by the L

J. Zeidler; E. Satorius; D. Chabries; H. Wexler

1978-01-01

256

Natural convection heat transfer from sinusoidal wavy surfaces  

Microsoft Academic Search

This paper presents the results of an experimental study of the natural convection heat transfer characteristics of sinusoidal wavy surfaces on vertical plates maintained at a constant temperature. Local heat transfer coefficients were obtained with a Mach-Zehnder interferometer. The heat transfer from the wavy surfaces, compared to a plane plate of equal projected area, increased with increasing amplitude-to-wavelength ratio. The

S. H. Bhavnani; A. E. Bergles

1991-01-01

257

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

USGS Publications Warehouse

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

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

1999-01-01

258

Chapter Nine Frequency Domain Controller Design  

E-print Network

Chapter Nine Frequency Domain Controller Design 9.1 Introduction Frequency domain techniques physical system driven by a sinusoidal input with a broad range of frequencies. The controller design;382 FREQUENCY DOMAIN CONTROLLER DESIGN gain stability margins and steady state errors. It is also possible

Gajic, Zoran

259

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

260

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

Microsoft Academic Search

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

John A. Houldsworth; Duncan A. Grant

1984-01-01

261

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

NASA Technical Reports Server (NTRS)

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

Lipo, Thomas A.; Sood, Pradeep K.

1987-01-01

262

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

263

Generation of High-Voltage Subnanosecond Pulses with a Peak Power of 700 MW and Repetition Frequency of Up to 3.5 kHz  

Microsoft Academic Search

Test results of a combined subnanosecond modulator with an output impedance of 45 O, which incorporates an all-solid-state high-voltage nanosecond charging device (with an inductive energy storage and a semiconductor opening switch) and a pulse sharpener with gas-filled gaps, are presented. The sharpening and cutting spark gaps filled with hydrogen at a pressure of 100 atm ensured the formation of

S. K. Lyubutin; G. A. Mesyats; S. N. Rukin; B. G. Slovikovskii; M. R. Ul'maskulov; V. G. Shpak; S. A. Shunailov; M. I. Yalandin

2001-01-01

264

Capacitance-voltage spectroscopy of silicon nanodots  

NASA Astrophysics Data System (ADS)

Frequency-dependent capacitance-voltage spectroscopy was applied to investigate the carrier transport dynamics in a silicon nanodots resonant tunneling device structure. Two negative differential resistance (NDR) regions in the current-voltage characteristics were found in this investigated structure. Two anomalous regions were also found in the capacitance-voltage spectroscopy, which coincide with the NDR regions in the current-voltage characteristics. The origin of the anomalous phenomenon was attributed to the mesoscopic quantum capacitance due to the holes transport through the energy states associated with the Si nanodots. An equivalent circuit model was proposed to quantitatively evaluate the frequency dependence of the capacitance-voltage spectroscopy.

Su, Alex Yu-Kwen; Hwang, H. L.; Pilkuhn, M. H.; Pei, Z.

2005-02-01

265

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

PubMed Central

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

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

1993-01-01

266

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

Microsoft Academic Search

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

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

2004-01-01

267

Evaluation of DMD-based high-precision beam shaper using sinusoidal-flattop beam profile generation  

NASA Astrophysics Data System (ADS)

We evaluate system performance of a high-precision beam shaper using a digital micromirror device (DMD) followed by a telescope with an adjustable pinhole low-pass filter. Beam shaping quality was measured by comparing the intensity and wave-front conformity with respect to the target image, and by the energy conversion efficiency. We previously demonstrated various flattop beams with high-precision intensity and a nearly uniform wave-front by using both coherent and incoherent light sources at visible and infrared wavelengths. The diffraction efficiency analysis determined optimized operation wavelengths for different diffraction orders. This paper extends beam shaping experiments to target images of a series of 2-D sinusoidal functions. An iterative pattern refinement process, based on the point spread function (PSF) of a single DMD pixel, was used to improve the image quality and to seek the optimized DMD binary pattern. Sinusoidal-flattop profiles with different spatial carrier frequencies were chosen for the purpose of system evaluation. Experiments demonstrated RMS error ranging from 0.95% to 11.87% in the raw camera image as the sinusoidal period was decreased. The DMD-based beam shaper achieved 1% RMS error level at low system bandwidth (large sinusoid period) and maintained 5% RMS error performance for a wide bandwidth range. We analyzed the relationship between spatial intensity error and system bandwidth. The ultimate system performance had amplitude error of +/-1 to +/-1.5 PSFs. Iterative refinement made a significant improvement in error for low system bandwidth as compared to the simulation of a DMD pattern designed by the error diffusion algorithm.

Liang, Jinyang; Kohn, Rudolph N., Jr.; Becker, Michael F.; Heinzen, Daniel J.

2011-10-01

268

Vestibular modulation of muscle sympathetic nerve activity by the utricle during sub-perceptual sinusoidal linear acceleration in humans.  

PubMed

We assessed the capacity for the vestibular utricle to modulate muscle sympathetic nerve activity (MSNA) during sinusoidal linear acceleration at amplitudes extending from imperceptible to clearly perceptible. Subjects (n = 16) were seated in a sealed room, eliminating visual cues, mounted on a linear motor that could deliver peak sinusoidal accelerations of 30 mG in the antero-posterior direction. Subjects sat on a padded chair with their neck and head supported vertically, thereby minimizing somatosensory cues, facing the direction of motion in the anterior direction. Each block of sinusoidal motion was applied at a time unknown to subjects and in a random order of amplitudes (1.25, 2.5, 5, 10, 20 and 30 mG), at a constant frequency of 0.2 Hz. MSNA was recorded via tungsten microelectrodes inserted into muscle fascicles of the common peroneal nerve. Subjects used a linear potentiometer aligned to the axis of motion to indicate any perceived movement, which was compared with the accelerometer signal of actual room movement. On average, 67% correct detection of movement did not occur until 6.5 mG, with correct knowledge of the direction of movement at ~10 mG. Cross-correlation analysis revealed potent sinusoidal modulation of MSNA even at accelerations subjects could not perceive (1.25-5 mG). The modulation index showed a positive linear increase with acceleration amplitude, such that the modulation was significantly higher (25.3 ± 3.7%) at 30 mG than at 1.25 mG (15.5 ± 1.2%). We conclude that selective activation of the vestibular utricle causes a pronounced modulation of MSNA, even at levels well below perceptual threshold, and provides further evidence in support of the importance of vestibulosympathetic reflexes in human cardiovascular control. PMID:24504198

Hammam, Elie; Hau, Chui Luen Vera; Wong, Kwok-Shing; Kwok, Kenny; Macefield, Vaughan G

2014-04-01

269

Thixotropy and Rheopexy of Muscle Fibers Probed Using Sinusoidal Oscillations  

PubMed Central

Length changes of muscle fibers have previously been shown to result in a temporary reduction in fiber stiffness that is referred to as thixotropy. Understanding the mechanism of this thixotropy is important to our understanding of muscle function since there are many instances in which muscle is subjected to repeated patterns of lengthening and shortening. By applying sinusoidal length changes to one end of single permeabilized muscle fibers and measuring the force response at the opposite end, we studied the history-dependent stiffness of both relaxed and activated muscle fibers. For length change oscillations greater than 1 Hz, we observed thixotropic behavior of activated fibers. Treatment of these fibers with EDTA and blebbistatin, which inhibits myosin-actin interactions, quashed this effect, suggesting that the mechanism of muscle fiber thixotropy is cross-bridge dependent. We modeled a half-sarcomere experiencing sinusoidal length changes, and our simulations suggest that thixotropy could arise from force-dependent cross-bridge kinetics. Surprisingly, we also observed that, for length change oscillations less than 1 Hz, the muscle fiber exhibited rheopexy. In other words, the stiffness of the fiber increased in response to the length changes. Blebbistatin and EDTA did not disrupt the rheopectic behavior, suggesting that a non-cross-bridge mechanism contributes to this phenomenon. PMID:25880774

Altman, David; Minozzo, Fabio C.; Rassier, Dilson E.

2015-01-01

270

Method and apparatus for spur-reduced digital sinusoid synthesis  

NASA Technical Reports Server (NTRS)

A technique for reducing the spurious signal content in digital sinusoid synthesis is presented. 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 that produced by a pseudo-noise (PN) generator are analyzed. This phase dithering method provides a spur reduction of 6(M + 1) 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 look-up 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.

Zimmerman, George A. (inventor); Flanagan, Michael J. (inventor)

1995-01-01

271

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. PMID:22984436

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

2012-01-01

272

The Impact of Voltage Generation on Harmonic Spectra of Current and Flux Density in the Welding Transformer for a Middle Frequency Resistance Spot Welding System  

Microsoft Academic Search

This paper deals with a middle frequency direct current (MFDC) resistance spot welding system (RSWS). It consists of a semiconductor input converter, a single-phase welding transformer with one primary coil and two secondary coils, and a full-wave output rectifier connected to the transformer's secondary coils. The unwanted current spikes in the input converter, caused by interaction among the asymmetrical design

G. Stumberger; K. Dezelak; B. Polajzer; D. Dolinar; B. Klopcic

2008-01-01

273

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

274

Fully integrated CMOS and high voltage compatible RF MEMS technology  

Microsoft Academic Search

In this paper, a fully integrated CMOS and high voltage compatible RF MEMS (radio frequency microelectromechanical systems) technology is proposed and demonstrated for the first time. The high performance RF MEMS switch, high voltage MOSFET, and CMOS devices are all obtained using a simple process. The fabricated high voltage device has a breakdown voltage of over 35V. The MEMS capacitive

Lingpeng Guan; J. K. O. Sin; Haitao Liu; Zhibin Xiong

2004-01-01

275

No energy stored power conditioners for voltage sag compensation  

Microsoft Academic Search

Voltage sags can be compensated at low voltage level through using no-energy stored voltage conditioners based on power electronic components. Different compensation principles and power semiconductor devices (SCRs, GTOs, IGBTs) can be used, with different expected performances. This paper illustrates the advantages offered in voltage sag compensation by conditioners based on high switching frequency components and underlines the need for

A. Boscolo; S. Quaia; F. Tosato

1998-01-01

276

Loads and propulsive efficiency of a flexible airfoil performing sinusoidal deformations  

NASA Astrophysics Data System (ADS)

This paper presents the application of state-space airloads theory to a flexible airfoil performing sinusoidal deformations at high Reynolds numbers. Given the two-dimensional motion of a flexible airfoil, we derived the closed forms for the propulsive force, lift force, generalized forces of pitching and bending as functions of reduced frequency k, dimensionless wavelength z, and dimensionless amplitude A/(2b). We also calculate the power required to perform this sinusoidal deformation and the propulsive efficiency. Our results show a positive, time-averaged propulsive force for all k>k0=?/z, which is when the wave speed is greater than the moving speed. At k=k0, which is when the moving speed reaches the wave speed, the motion reaches a steady-state with all forces being zero. When k

Ulrich, Xialing; Peters, David

2014-02-01

277

Sinusoidal Obstruction Syndrome (Hepatic Veno-Occlusive Disease)  

PubMed Central

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

Fan, Cathy Q.; Crawford, James M.

2014-01-01

278

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

279

Experimental studies for determining human discomfort response to vertical sinusoidal vibration  

NASA Technical Reports Server (NTRS)

A study was conducted to investigate several problems related to methodology and design of experiments to obtain human comfort response to vertical sinusoidal vibration. Specifically, the studies were directed to the determination of (1) the adequacy of frequency averaging of vibration data to obtain discomfort predictors, (2) the effect of practice on subject ratings, (3) the effect of the demographic factors of age, sex, and weight, and (4) the relative importance of seat and floor vibrations in the determination of measurement and criteria specification location. Results indicate that accurate prediction of discomfort requires knowledge of both the acceleration level and frequency content of the vibration stimuli. More importantly, the prediction of discomfort was shown to be equally good based upon either floor accelerations or seat accelerations. Furthermore, it was demonstrated that the discomfort levels in different seats resulting from similar vibratory imputs were equal. Therefore, it was recommended that criteria specifications and acceleration measurements be made at the floor location. The results also indicated that practice did not systematically influence discomfort responses nor did the demographic factors of age, weight, and sex contribute to the discomfort response variation.

Dempsey, T. K.; Leatherwood, J. D.

1975-01-01

280

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

E-print Network

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

Dreyer, Anna Alexandra

2005-01-01

281

Synchronization in a pool of mutually coupled oscillators with random frequencies  

Microsoft Academic Search

An exact solution to a model of mutually interacting sinusoidal oscillators is found. Limits on the variation of the native frequencies are determined in order for synchronization to occur. These limits are computed for different distributions of native frequencies.

G. Bard Ermentrout

1985-01-01

282

Multiresolution sinusoidal model with dynamic segmentation for timescale modification of polyphonic audio signals  

Microsoft Academic Search

In this paper, we propose an efficient sinusoidal model of polyphonic audio signals especially good for the application of timescale modification. One of the critical problem of sinusoidal modeling is that the signal is smeared during the synthesis frame, which is a very undesirable effect for transient parts. We solve this problem by introducing multiresolution analysis-synthesis and dynamic segmentation methods.

Ho Keun Jang; Ju Sung Park

2005-01-01

283

Temperature distribution in an oscillatory flow with a sinusoidal wall temperature  

E-print Network

Temperature distribution in an oscillatory flow with a sinusoidal wall temperature Eduardo Ramos a­­UNAM, Ap. P. 34, Temixco Morelos 62580, Mexico Received 18 October 2002 Abstract The temperature field generated by an oscillatory boundary layer flow in the presence of a wall with a sinusoidal temperature

Texas at Austin. University of

284

Modulation of simple sinusoidal patterns by a coupled oscillator model for biped walking  

E-print Network

sinusoidal patterns. The aim of Fig. 1. (Left) Our human sized hydraulic humanoid robot developed by SARCOS and Christopher G. Atkeson The Robotics Institute, Carnegie Mellon University 5000 Forbes Ave., Pittsburgh, PA, 15213, USA Abstract-- We show that a humanoid robot can step and walk using simple sinusoidal desired

Atkeson, Christopher G.

285

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

286

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

287

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; Lai, Jih-Sheng

2001-04-03

288

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

289

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

290

Spontaneous immortalization of mouse liver sinusoidal endothelial cells  

PubMed Central

The spontaneous immortalization of cells in vitro is a rare event requiring genomic instability, such as alterations in chromosomes and mutations in genes. In the present study, we report a spontaneously immortalized liver sinusoidal endothelial cell (LSEC) line generated from mouse liver. These immortalized LSECs showed typical LSEC characteristics with the structure of transcellular fenestrations, the expression of von Willebrand factor (VWF) and the ability to uptake DiI-acetylated-low density lipoprotein (DiI-Ac-LDL). However, these immortalized LSECs lost the ability to form capillary-like structures, and showed clonal and multilayer growth without contact inhibition. Moreover, their proliferation rate increased with the increase in the number of passages. In addition, these cells obained the expression of CD31 and desmin, and showed an upregulation of p53 protein expression; however, their karyotype was normal, and they could not form colonies in soft agar or tumors in SCID mice. In conclusion, in the present study, we successfully established a spontaneously immortalized LSEC line. PMID:25585915

ZHAO, XIUHUA; ZHAO, QIAN; LUO, ZHEN; YU, YAN; XIAO, NA; SUN, XUAN; CHENG, LAMEI

2015-01-01

291

Molecular response of liver sinusoidal endothelial cells on hydrogels.  

PubMed

There is a high demand for the isolation of primary endothelial cells for biomaterial endotheliazation studies, tissue engineering, and artificial organ development. Further, biomarkers for monitoring the response of endothelial cells in biomaterials science are required. We systematically compared two strategies for isolating liver sinusoidal endothelial cells (LSEC) from mouse liver. We demonstrate that fluorescence-activated cell sorting results in a considerably higher purity (~97%) compared to magnetic-assisted cell sorting (~80%), but is associated with a lower yield and recovery rate. Cell repellent polyethylene glycol (PEG) substrates affected the morphology of primary LSEC in culture and significantly downregulated the intracellular adhesion molecule (ICAM) and upregulated the vascular cell adhesion molecule (VCAM). This molecular response could partially be reverted by further modification with arginylglycylaspartic acid (RGD). Thus, usage of PEGylated materials may reduce, while applying RGD may support endotheliazation of materials, and we could relate LSEC attachment to their expression of ICAM and VCAM mRNA, suggesting their usage as biomarkers for endothelialization. PMID:25842109

Bartneck, Matthias; Topuz, Fuat; Tag, Carmen Gabriele; Sauer-Lehnen, Sibille; Warzecha, Klaudia Theresa; Trautwein, Christian; Weiskirchen, Ralf; Tacke, Frank

2015-06-01

292

Interaction of a Shock with a Sinusoidally Perturbed Flame  

NASA Astrophysics Data System (ADS)

The interaction of a shock wave and a sinusoidally perturbed premixed flame was studied using reactive 2D and 3D Navier-Stokes simulations resolved down to the viscous microscale. The chemical model reproduced the combustion properties of a mixture of stoichiometric acetylene-air. The range of Mach numbers considered (1.25 - 3.0) is too low to cause direct detonation initiation. The basic interaction is a Richtmyer-Meshkov instability that creates vorticity, increases the surface area of the flame, and increases the energy-release rate. Vortices present long after the shock wave has passed through the flame maintain a high level of energy release. 3D perturbations (of given amplitude and wavelength) grow a factor of ~= 2 faster than comparable 2D perturbations, and the maximum energy-release rate is a factor of ~= 2 larger in 3D. The vorticity generated is too weak to stretch and extinguish the flame locally. The maximum increase in the energy generation rate due the interaction is at most a factor of 20 to 30. To greatly increase the burning rate, multiple shock-flame interactions are required.

Oran, Elaine; Khokhlov, Alexei

1997-11-01

293

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

NASA Technical Reports Server (NTRS)

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

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

1992-01-01

294

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

295

Pulsed high-voltage dc RF sputtering  

NASA Technical Reports Server (NTRS)

Sputtering technique uses pulsed high voltage direct current to the object to be plated and a radio frequency sputtered film source. Resultant film has excellent adhesion, and objects can be plated uniformly on all sides.

Przybyszewski, J. S., Jr.; Shaltens, R. K.

1969-01-01

296

Peliosis hepatis and sinusoidal dilation during infection by the human immunodeficiency virus (HIV). An ultrastructural study.  

PubMed Central

The description of hepatic sinusoidal lesions in a significant number of acquired immunodeficiency syndrome (AIDS) patients prompted the authors to undertake an ultrastructural study of the sinusoidal barrier abnormalities during human immunodeficiency virus (HIV) infection, in order to compare these lesions with those described in other conditions and to discuss their possible origin. In a series of 29 patients with serologic evidence of HIV infection and liver abnormalities, 8 (28%) had sinusoidal lesions. Peliosis hepatis was present in 2 cases, and sinusoidal dilatation in 6. These patients were classified as follows: 3 AIDS, 4 AIDS-related complex, 1 unclassifiable. Ultrastructural lesions of the sinusoidal barrier were observed in all the cases. They closely mimicked the changes previously reported in peliotic and peliotic-like changes of various origins. A striking particularity was, however, the presence of numerous and hyperplastic sinusoidal macrophages. This work suggests that an injury of the endothelial cells, directly or indirectly related to the presence of HIV, may be incriminated in the pathogenesis of sinusoidal lesions during HIV infection. Images Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 PMID:3354642

Scoazec, J. Y.; Marche, C.; Girard, P. M.; Houtmann, J.; Durand-Schneider, A. M.; Saimot, A. G.; Benhamou, J. P.; Feldmann, G.

1988-01-01

297

Frequency Response Measurement for Periodic Test Signals  

Microsoft Academic Search

\\u000a The frequency response measurement with periodic test signals allows the determination of the relevant frequency range for\\u000a linear systems for certain, discrete points in the frequency spectrum. Typically, one uses sinusoidal signals at fixed frequencies,\\u000a see Sect. 5.1. However, one can also use other periodic signals such as e.g. rectangular, trapezoidal, or triangular signals\\u000a as shown in Sect. 5.2. The

Rolf Isermann; Marco Münchhof

298

High-rate conditioning pulse trains in cochlear implants: dynamic range measures with sinusoidal stimuli.  

PubMed

The addition of a continuous, unmodulated, high-rate pulse train to the electrical signals of cochlear implant recipients results in statistically significant increases in psychophysical dynamic range (41 out of 46 electrode pairs tested). The observed increases in dynamic range are thought to result from nerve conditioning by appropriate levels of high-rate pulse train. Five dynamic range profiles are characterized, defining the different responses of dynamic range observed with increasing levels of the conditioner. Four of the five profiles demonstrate increases in dynamic range, with three showing behavior consistent with stochastic resonance. One profile depicts evidence of adaptation in response to higher levels of the conditioner, with a recovery period lasting throughout the duration (on the scale of tens of minutes) of experimentation. Dynamic range profiles are shown to be similar across sinusoidal frequencies (202, 515, and 1031 Hz) but potentially different across electrode pairs (electrodes 1-2, 7-8, and 15-16). Correlation analysis does not reveal any predictors of optimal conditioner level or amount of dynamic range increase with the conditioner. PMID:14714813

Hong, Robert S; Rubinstein, Jay T

2003-12-01

299

A new approach to active noise and vibration control-part I: the known frequency case  

Microsoft Academic Search

This paper presents a new approach to rejection of complex-valued sinusoidal disturbances acting at the output of a discrete-time stable linear plant with unknown dynamics. It is assumed that the frequency of the sinusoidal disturbance is known, and that the output signal is contaminated with wideband measurement noise. The disturbance rejection control rule is first derived and analyzed for a

Maciej Niedzwiecki; Michal Stanislaw Meller

2009-01-01

300

Experimental validation of a high voltage pulse measurement method.  

SciTech Connect

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

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

2013-09-01

301

Accurate frequency estimation using SVD method and Steiglitz-McBride algorithm  

Microsoft Academic Search

In many applications it is desired to estimate frequencies of sinusoids from a signal which is contaminated by a white noise. The Steiglitz-McBride algorithm (S-MA) works well for one sinusoid or when frequencies are seperated widely. However, when frequencies are close, the S-MA does not work. In the S-MA the initial estimate of the characteristic equation coefficients is based on

Sung-won Park; A. Kattinanon

1998-01-01

302

Effect of hepatic venous outflow obstruction on pores and fenestration in sinusoidal endothelium.  

PubMed Central

The ultrastructure of pores and fenestrations in hepatic sinusoidal endothelial cells was examined following partial surgical occlusion of the suprahepatic portion of the inferior vena cava. Within 12 h after partial obstruction of hepatic venous outflow, endothelial pores (less than 0-1 mum in diameter) and sieve plates in the distal halves of sinusoids were greatly reduced in number or were totally absent, and they were replaced by large fenestration (less than 1-0 mum in diameter). These results suggest that pores forming sieve plates may fuse to form large fenestrations. The findings also indicate that sinusoidal hypertension and hypoxia associated with obstruction of hepatic venous outflow alter the distribution of pores and fenestrations in sinusoidal endothelium Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6 Fig. 7 PMID:999794

Nopanitaya, W.; Lamb, J. C.; Grisham, J. W.; Carson, J. L.

1976-01-01

303

Precision voltage regulator  

NASA Technical Reports Server (NTRS)

Balanced positive and negative voltage output circuit, in which error voltage for control is developed from difference in absolute value of positive and negative voltages referenced to a common point, regulates voltage for use with inertial reference unit. Fast-acting, temperature-compensated, high-gain operational amplifier circuits maintain common point.

Hand, P. J.; Crawford, R. A.

1972-01-01

304

Right Ventricular Myocardial Sinusoidal–Coronary Artery Connections in Critical Pulmonary Valve Stenosis  

Microsoft Academic Search

.   Ventriculo-coronary arterial connections are frequently observed in pulmonary atresia with intact interventricular septum.\\u000a Sustained right ventricular hypertension during cardiac morphogenesis is thought to be responsible for persistence of myocardial\\u000a sinusoidal–coronary artery connections. Considering an unusual observation of ventriculo-coronary arterial connections in\\u000a a patient with critical pulmonary valve stenosis, we speculate that sinusoidal connections in pulmonary atresia with intact\\u000a ventricular

D. Bonnet; I. Gautier-Lhermitte; P. Bonhoeffer; D. Sidi

1998-01-01

305

An iterative filterbank approach for extracting sinusoidal parameters from quasi-harmonic sounds  

Microsoft Academic Search

We propose an iterative filterbank method for tracking the parameters of exponentially damped sinusoidal components of quasi-harmonic sounds. The quasi-harmonic criteria specialize our analysis to a wide variety of acoustic instrument recordings while allowing for inharmonicity. The filterbank splits the recorded signal into subbands, one per harmonic, in which time-varying parameters of multiple closely-spaced sinusoids are estimated using a Steiglitz-McBride\\/Kalman

Harvey D. Thornburg; Randal J. Leistikow

2003-01-01

306

A Low Total Harmonic Distortion Sinusoidal Oscillator Based on Digital Harmonic Cancellation Technique  

E-print Network

Page Fig. 2.14. Feedback-based sinusoidal oscillator with two-level-comparator .................... 32 Fig. 2.15. Root locus when oscillation amplitude increases ............................................. 34 Fig. 2.16. Spectrum response of BPF...-level comparator ................. 37 Fig. 2.19. Spectrum response of BPF input and output with multi-level comparator ...... 38 Fig. 2.20. Sinusoidal oscillator with direct-loop-based-architecture ................................ 39 Fig. 2.21. Block diagram...

Yan, Jun

2012-07-16

307

TRACKING INTERMITTENT TREMOR FREQUENCY WITH A PARTICLE FILTER Sunghan Kim  

E-print Network

TRACKING INTERMITTENT TREMOR FREQUENCY WITH A PARTICLE FILTER Sunghan Kim and James Mc) is a suitable method to track tremor frequencies embedded in spike trains, whose firing rate can be modeled as a sinusoid contaminated with noise. However, when tremor is intermittent, the EKF frequency tracker takes

308

Expression of DC-SIGN and DC-SIGNR on Human Sinusoidal Endothelium  

PubMed Central

Hepatic sinusoidal endothelial cells are unique among endothelial cells in their ability to internalize and process a diverse range of antigens. DC-SIGNR, a type 2 C-type lectin expressed on liver sinusoids, has been shown to bind with high affinity to hepatitis C virus (HCV) E2 glycoprotein. DC-SIGN is a closely related homologue reported to be expressed only on dendritic cells and a subset of macrophages and has similar binding affinity to HCV E2 glycoprotein. These receptors function as adhesion and antigen presentation molecules. We report distinct patterns of DC-SIGNR and DC-SIGN expression in human liver tissue and show for the first time that both C-type lectins are expressed on sinusoidal endothelial cells. We confirmed that these receptors are functional by demonstrating their ability to bind HCV E2 glycoproteins. Although these lectins on primary sinusoidal cells support HCV E2 binding, they are unable to support HCV entry. These data support a model where DC-SIGN and DC-SIGNR on sinusoidal endothelium provide a mechanism for high affinity binding of circulating HCV within the liver sinusoids allowing subsequent transfer of the virus to underlying hepatocytes, in a manner analogous to DC-SIGN presentation of human immunodeficiency virus on dendritic cells. PMID:16816373

Lai, Wai K.; Sun, Phoebe J.; Zhang, Jie; Jennings, Adam; Lalor, Patricia F.; Hubscher, Stefan; McKeating, Jane A.; Adams, David H.

2006-01-01

309

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. PMID:18386215

Warren, Alessandra; Chaberek, Slawomir; Ostrowski, Kazimierz; Cogger, Victoria C.; Hilmer, Sarah N.; McCuskey, Robert S.; Fraser, Robin; Le Couteur, David G.

2011-01-01

310

Characteristics of probe current harmonics based on various applied voltage waveforms in low temperature plasmas  

SciTech Connect

The characteristics of probe currents induced by applying various probe voltage waveforms, such as sinusoidal, sawtooth, square, and triangular, were investigated at a floating potential. It was found that the measured probe currents have many harmonics depending on the voltage waveforms. This was mainly due to the nonlinearity of the sheath in the plasma and was analyzed using the fast Fourier transform and a circuit model. By applying a triangular voltage waveform to a probe, plasma parameters such as electron temperature and plasma density could be obtained and compared to those of a single Langmuir probe and a floating harmonic method.

Kim, Young-Do; Kim, Yu-Sin; Lee, Hyo-Chang; Bang, Jin-Young; Chung, Chin-Wook [Department of Electrical Engineering, Hanyang University, 17 Heangdang-dong, Seongdong-gu, Seoul 133-791 (Korea, Republic of)

2011-03-15

311

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

PubMed Central

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

2014-01-01

312

Dynamics of the heart rate response to sinusoidal work in humans: influence of physical activity and age.  

PubMed

The purpose of the present study was to define the influence of age and exercise training on the heart rate (HR) dynamic response (i.e. kinetics) to sinusoidal work. A total of 63 healthy subjects (31 men and 32 women; age range 19-69 years) underwent a three-step incremental work test, during which peak oxygen uptake (.V(O)(2peak)) was estimated by the YMCA method. Sinusoidal work varying between 20% and 60% of HR(reserve) was employed for periods of 1, 3, 6, 9 and 12 min. HR was monitored in a beat-by-beat manner with a cardiotachometer. The kinetics of the HR response were analysed by frequency analysis and estimated by a first-order transfer function with time constant (tau) and time delay (TD). Physical training status was estimated as stepping frequency, as measured with a pedometer during the daytime, and averaged over seven consecutive days. The mean response time of HR kinetics (HR(MRT): tau pulse TD) tended to increase gradually with age (0.36 s.year(-1)), and linear regression analysis revealed that the correlation between HR(MRT) and age was significant (r=0.31, P<0.05), although not as highly significant as that between HR(MRT) and physical activity (r=-0.48, P<0.0001). HR(MRT) was not related to the S.D. of HR variation (an indicator of parasympathetic mediation) at rest. In addition, .V(O)(2peak) showed a significantly greater correlation with age (r=-0.60, P<0.0001) than with physical activity (r=-0.14, not significant). In conclusion, these findings suggest that HR dynamics, which may depend on sympathetic nervous activity, are more sensitive to physical activity than to age, but that .V(O)(2peak), as estimated by the age-associated decline in maximum HR, is unrelated to physical training status. PMID:11749658

Fukuoka, Yoshiyuki; Nakagawa, Yoko; Ogoh, Katsutoshi; Shiojiri, Tomoyuki; Fukuba, Yoshiyuki

2002-01-01

313

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. PMID:19535440

Seckert, Christof K.; Renzaho, Angélique; Tervo, Hanna-Mari; Krause, Claudia; Deegen, Petra; Kühnapfel, Birgit; Reddehase, Matthias J.; Grzimek, Natascha K. A.

2009-01-01

314

Responses of central vestibular neurons to sinusoidal yaw rotation in compensated macaques after unilateral labyrinthectomy  

PubMed Central

After vestibular labyrinth injury, behavioral measures of vestibular function partially recover through the process of vestibular compensation. The present study was performed to improve our understanding of the physiology of macaque vestibular nucleus neurons in the compensated state (>6 wk) after unilateral labyrinthectomy (UL). The responses of neurons to sinusoidal yaw rotation at a series of frequencies (0.1–2.0 Hz) and peak velocities (7.5–210°/s) were examined to determine how the behavior of these cells differed from those in animals with intact labyrinths. The sensitivity of neurons responding to ipsilateral rotation (type I) did not differ between the intact and injured sides after UL, although this sensitivity was lower bilaterally after lesion than before lesion. The sensitivity of neurons that increase firing with contralateral rotation (type II) was higher ipsilateral to the UL than before lesion or in the nucleus contralateral to the UL. UL did not increase asymmetry in the responses of individual type I or II neurons to ipsilateral vs. contralateral rotation, nor does it change the power law relationship between neuronal firing and level of stimulation. Increased sensitivities of contralesional type I neurons to the remaining vestibular nerve input and increased efficacy of inhibitory vestibular commissures projecting to the ipsilesional vestibular nucleus appear to be responsible for recovery of dynamic function of central vestibular neurons in compensated animals. The portion of type I neurons on the ipsilesional side is reduced in compensated animals, which likely accounts for the asymmetries in vestibular reflexes and perception that characterize vestibular function after UL. PMID:23864379

Wei, Min

2013-01-01

315

Streaming potentials maps are spatially resolvedind icators of amplitude, frequency and ionic strength dependant responses of articular cartilage to load  

Microsoft Academic Search

Streaming potential distributions were measured on the surface of articular cartilage in uniaxial unconfined compression using a linear array of microelectrodes. Potential profiles were obtained for sinusoidal and ramp\\/stress-relaxation displacements and exhibited dependencies on radial position, sinusoidal amplitude and frequency, time during stress relaxation, and on ionic strength. The measurements agreed with trends predicted by biphasic and related models. In

R. Guardo; P. Savard; M. D. Buschmann

316

Generating Electrical Voltage  

NSDL National Science Digital Library

This interactive resource adapted from the Wisconsin Online Resource Center illustrates how electrical voltage is generated through a process called magnetic induction and describes some of the factors that affect the magnitude of the voltage produced.

WGBH Educational Foundation

2009-12-24

317

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

318

Highly linear voltage-controlled CMOS transconductors  

Microsoft Academic Search

A circuit technique for realizing voltage-tunable linear high-frequency CMOS transconductor cells that use two cross-coupled MOS or CMOS transistor pairs operating at saturation is described. The tuning capabilities attained with an adjustable CMOS voltage source are examined. Design trade-offs between linearity and bandwidth are discussed, and a simple operational transconductance amplifier (OTA) example is simulated via SPICE. The simulation results

S. Szczepanski; A. Wyszynski; Rolf Schaumann

1993-01-01

319

Dynamic optical frequency domain reflectometry.  

PubMed

We describe a dynamic Optical Frequency Domain Reflectometry (OFDR) system which enables real time, long range, acoustic sensing at high sampling rate. The system is based on a fast scanning laser and coherent detection scheme. Distributed sensing is obtained by probing the Rayleigh backscattered light. The system was tested by interrogation of a 10 km communication type single mode fiber and successfully detected localized impulse and sinusoidal excitations. PMID:24787772

Arbel, Dror; Eyal, Avishay

2014-04-21

320

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

321

High-Frequency Resonant Transistor DC-DC Converters  

Microsoft Academic Search

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

Robert L. Steigerwald

1984-01-01

322

Microwave integrated circuit for Josephson voltage standards  

NASA Technical Reports Server (NTRS)

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

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

1980-01-01

323

High Voltage SPT Performance  

NASA Technical Reports Server (NTRS)

A 2.3 kW stationary plasma thruster designed to operate at high voltage was tested at discharge voltages between 300 and 1250 V. Discharge specific impulses between 1600 and 3700 sec were demonstrated with thrust between 40 and 145 mN. Test data indicated that discharge voltage can be optimized for maximum discharge efficiency. The optimum discharge voltage was between 500 and 700 V for the various anode mass flow rates considered. The effect of operating voltage on optimal magnet field strength was investigated. The effect of cathode flow rate on thruster efficiency was considered for an 800 V discharge.

Manzella, David; Jacobson, David; Jankovsky, Robert

2001-01-01

324

F-TF.A, F-BF.A.3 Exploring Sinusoidal Functions  

NSDL National Science Digital Library

This is a task from the Illustrative Mathematics website that is one part of a complete illustration of the standard to which it is aligned. Each task has at least one solution and some commentary that addresses important asects of the task and its potential use. Here are the first few lines of the commentary for this task: In this task we will explore the effect that changing the parameters in a sinusoidal function has on the graph of the function. A general sinusoidal fu...

325

Comparison between LCOS projector and DLP projector in generating digital sinusoidal fringe patterns  

NASA Astrophysics Data System (ADS)

Digital-light-processing (DLP) and liquid-crystal-on-silicon (LCOS) are two digital projection technologies which enjoy great popularity. This paper will demonstrate the performance of the two technologies in generating digital sinusoidal fringe patterns in the two following ways: focused-sinusoidal-patterns (FSP) method and defocused-binary-patterns (DBP) method. Experiment shows that for the FSP method, LCOS projector is a better choice since nonlinear gamma effect is less significant and there is no need for precise synchronization; While for the DBP method, DLP projector has the advantage over LCOS projector since the generated images have higher contrast ratio.

Li, Beiwen; Gibson, John; Middendorf, Jill; Wang, Yajun; Zhang, Song

2013-09-01

326

DVSST: A Dynamic Voltage Scaling Algorithm for Sporadic Tasks Ala Qadi Steve Goddard  

E-print Network

frequency and thus on a lower voltage. In CMOS circuits the power consumed by a CMOS gate is proportional to the square of the voltage applied to the circuit, as shown by Equation (1) where CL is the gate load capacitance (output capacitance),VDD is the supply voltage and f is the clock frequency [27]. The circuit

Goddard, Steve

327

A Design of High-precision High-Voltage Fiber-Optic Analog Signal Isolation Converter  

Microsoft Academic Search

This paper introduces a design of high-precision high-voltage fiber-optic analog signal isolation converter based on the technology of Voltage-to-Frequency (V\\/F) and Frequency-to-Voltage (F\\/V) conversion. It describes the principle, system configuration and hardware design.

Jian-wei Li; Liu-wei Xu; Xiao-ning Liu; Lei Yang

2002-01-01

328

The generalization of A. E. Kennelly theory of complex representation of the electrical quantities in sinusoidal periodic regime to the one and three-phase electric quantities in non-sinusoidal periodic regime  

E-print Network

In this paper, a new mathematical method of electrical circuits calculus is proposed based on the theory of the complex linear operators in matrix form. The newly proposed method generalizes the theory of complex representation of electrical quantities in sinusoidal periodic regime to the non-sinusoidal periodic regime.

Gheorghe Mihai

2010-02-12

329

ELEC 433: Building a Sinusoid Generator Evan Everett and Michael Wu  

E-print Network

into a Xilinx Platform Studio (XPS) project. 1. Before generating theHDL core, set the initial value value of the phaseInc. #12;4. Open the SystemGenerator block. It will reveal a whole set of optionsELEC 433: Building a Sinusoid Generator Evan Everett and Michael Wu February 2013 Buildingthe

330

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

331

Dynamic sorption and hygroexpansion of wood wafers exposed to sinusoidally varying humidity  

Microsoft Academic Search

Round wood wafers, 4 mm thick along the grain and 2 cm in cross-sectional diameter, of green basswood (Tilia americana L.), yellow birch (Betula alleghaniensis Britton), and black cherry (Prunus serotina Ehrh.), and initially dried to equilibrium in air of 77% relative humidity and 25°C, were exposed to sinusoidally varying relative humidity between 77 and 47% at 25°C for many

A. Chomcharn; C. Skaar

1983-01-01

332

Experimental study on drag-reduction effect due to sinusoidal riblets in turbulent channel flow  

NASA Astrophysics Data System (ADS)

The drag-reduction effect of a three-dimensional sinusoidal riblet surface is experimentally evaluated in a fully developed turbulent channel flow. The lateral spacing of the adjacent walls of the riblet is varied sinusoidally in the streamwise direction. The obtained maximum total drag-reduction rate is approximately 12 % at a bulk Reynolds number of 3,400. The flow structure over the sinusoidal riblet surface is also analyzed in the velocity field by using two-dimensional particle image velocimetry. The velocity field is compared with the corresponding flow over a flat surface. It is found through pathlines and Reynolds shear stress analyses that the drag-reduction mechanism is similar to those of two-dimensional riblets. A different point is that the present riblet respectively induces a downward and upward flows in the expanded and contracted regions, which prevent vortices from hitting the bottom wall with wider lateral spacing of the riblet. In consequence, the wetted area of the present sinusoidal riblet is smaller than those of two-dimensional riblets, resulting in the high drag-reduction effect.

Sasamori, M.; Mamori, H.; Iwamoto, K.; Murata, A.

2014-10-01

333

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...

334

Design considerations of sinusoidally excited permanent magnet machines for low torque ripple applications  

Microsoft Academic Search

Several high performance applications such as electric power steering require, the motor drive to produce smooth torque with very stringent torque ripple requirement. This paper is focused on various machine design considerations that can be used in reducing the torque ripple of a sinusoidally excited permanent magnet (PM) brushless DC (BLDC) motor. The paper quantifies the various sources of torque

Mohammad S. Islam; Sayeed Mir; Tomy Sebastian; Samuel Underwood

2004-01-01

335

Frequency Estimation Techniques For High Dynamic Trajectories  

NASA Technical Reports Server (NTRS)

Report presents comparative study of four techniques for estimating frequency of sinusoidal signal received in presence of noise when transmitter and/or receiver experiencing very high dynamics. Four techniques involve approximate-maximum-likelihood estimator, extended Kalman filter, cross-product automatic frequency control loop, and digital phase locked loop, respectively. In numerical simulations, each technique applied to signal from transmitter maneuvering along common trajectory; performance of each examined to determine its useful operating range, and performances compared.

Vilnrotter, V. A.; Hinedi, S. M.; Kumar, R.

1989-01-01

336

Voltage Converter TYPICAL APPLICATION  

E-print Network

s Inverting and Doubling Modes s Minimum Open Circuit Voltage Conversion Efficiency: 99% s Typical Power Voltage RL = 1k Inverter, LV = Open q 3 5.5 V Inverter, LV = GND q 1.5 5.5 V Doubler, LV = VOUT q 2.5 5 % Voltage Conversion Efficiency No Load 99 99.96 % Oscillator Sink or Source Current Boost = Open ±1.1 µ

Berns, Hans-Gerd

337

ON THE JOINT BAYESIAN MODEL SELECTION AND ESTIMATION OF SINUSOIDS VIA REVERSIBLE JUMP MCMC IN LOW SNR SITUATIONS  

E-print Network

of signals used in these applications. The problem of joint detection and estimation of sinusoids in low SNR is the white Gaussian noise of variance 2 . The unknown parameters are assumed to be the number of components kON THE JOINT BAYESIAN MODEL SELECTION AND ESTIMATION OF SINUSOIDS VIA REVERSIBLE JUMP MCMC IN LOW

Paris-Sud XI, Université de

338

Liver sinusoidal endothelial cells are a site of murine cytomegalovirus latency and reactivation.  

PubMed

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 10(4) 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. PMID:19535440

Seckert, Christof K; Renzaho, Angélique; Tervo, Hanna-Mari; Krause, Claudia; Deegen, Petra; Kühnapfel, Birgit; Reddehase, Matthias J; Grzimek, Natascha K A

2009-09-01

339

An Effective Control Technique for Medium-Voltage High-Power Induction Motor Fed by Cascaded Neutral-Point-Clamped Inverter  

Microsoft Academic Search

For a cascaded neutral-point-clamped (NPC) inverter applied to the medium-voltage high-power induction-motor (IM) drives, an effective control technique is proposed in this paper. The novel sinusoidal pulsewidth modulation (PWM) pulse-rotation-control approach, for a wide range of output voltage, provides a simple way to implement vector control for IM when the cascaded NPC inverter is employed. The proposed method presents great

Baoming Ge; Fang Zheng Peng; Aníbal T. de Almeida; Haitham Abu-Rub

2010-01-01

340

Voltage fed zero-voltage zero-current switching PWM DC-DC converter  

Microsoft Academic Search

A new zero-voltage zero-current switching full-bridge phase-shifted PWM converter with controlled output rectifier is presented in this paper. IGBT switches are used in the high-frequency inverter of the DC-DC converter. Zero-voltage turn-on and zero-current turn-off for all power switches of the inverter is achieved for full load range from no-load to short circuit by using new secondary energy recovery clamp

Jaroslav Dudrik; V. Ruscin

2008-01-01

341

Cascaded voltage collapse  

SciTech Connect

The dynamic phenomena of voltage collapse are analyzed by the method of dynamic simulation using induction motor models. From the view point of dynamic phenomena, the voltage collapse starts locally at the weakest node and spreads out to the other weak nodes.

Sekine, Y. (Tokyo Univ. (Japan)); Ohtsuki, H. (Kansai Electric Power Co., Inc., Osaka (Japan))

1990-02-01

342

Analytical model for the radio-frequency sheath.  

PubMed

A simple analytical model for the planar radio-frequency (rf) sheath in capacitive discharges is developed that is based on the assumptions of a step profile for the electron front, charge exchange collisions with constant cross sections, negligible ionization within the sheath, and negligible ion dynamics. The continuity, momentum conservation, and Poisson equations are combined in a single integro-differential equation for the square of the ion drift velocity, the so called sheath equation. Starting from the kinetic Boltzmann equation, special attention is paid to the derivation and the validity of the approximate fluid equation for momentum balance. The integrals in the sheath equation appear in the screening function which considers the relative contribution of the temporal mean of the electron density to the space charge in the sheath. It is shown that the screening function is quite insensitive to variations of the effective sheath parameters. The two parameters defining the solution are the ratios of the maximum sheath extension to the ion mean free path and the Debye length, respectively. A simple general analytic expression for the screening function is introduced. By means of this expression approximate analytical solutions are obtained for the collisionless as well as the highly collisional case that compare well with the exact numerical solution. A simple transition formula allows application to all degrees of collisionality. In addition, the solutions are used to calculate all static and dynamic quantities of the sheath, e.g., the ion density, fields, and currents. Further, the rf Child-Langmuir laws for the collisionless as well as the collisional case are derived. An essential part of the model is the a priori knowledge of the wave form of the sheath voltage. This wave form is derived on the basis of a cubic charge-voltage relation for individual sheaths, considering both sheaths and the self-consistent self-bias in a discharge with arbitrary symmetry. The externally applied rf voltage is assumed to be sinusoidal, although the model can be extended to arbitrary wave forms, e.g., for dual-frequency discharges. The model calculates explicitly the cubic correction parameter in the charge-voltage relation for the case of highly asymmetric discharges. It is shown that the cubic correction is generally moderate but more pronounced in the collisionless case. The analytical results are compared to experimental data from the literature obtained by laser electric field measurements of the mean and dynamic fields in the capacitive sheath for various gases and pressures. Very good agreement is found throughout. PMID:24483571

Czarnetzki, Uwe

2013-12-01

343

Analytical model for the radio-frequency sheath  

NASA Astrophysics Data System (ADS)

A simple analytical model for the planar radio-frequency (rf) sheath in capacitive discharges is developed that is based on the assumptions of a step profile for the electron front, charge exchange collisions with constant cross sections, negligible ionization within the sheath, and negligible ion dynamics. The continuity, momentum conservation, and Poisson equations are combined in a single integro-differential equation for the square of the ion drift velocity, the so called sheath equation. Starting from the kinetic Boltzmann equation, special attention is paid to the derivation and the validity of the approximate fluid equation for momentum balance. The integrals in the sheath equation appear in the screening function which considers the relative contribution of the temporal mean of the electron density to the space charge in the sheath. It is shown that the screening function is quite insensitive to variations of the effective sheath parameters. The two parameters defining the solution are the ratios of the maximum sheath extension to the ion mean free path and the Debye length, respectively. A simple general analytic expression for the screening function is introduced. By means of this expression approximate analytical solutions are obtained for the collisionless as well as the highly collisional case that compare well with the exact numerical solution. A simple transition formula allows application to all degrees of collisionality. In addition, the solutions are used to calculate all static and dynamic quantities of the sheath, e.g., the ion density, fields, and currents. Further, the rf Child-Langmuir laws for the collisionless as well as the collisional case are derived. An essential part of the model is the a priori knowledge of the wave form of the sheath voltage. This wave form is derived on the basis of a cubic charge-voltage relation for individual sheaths, considering both sheaths and the self-consistent self-bias in a discharge with arbitrary symmetry. The externally applied rf voltage is assumed to be sinusoidal, although the model can be extended to arbitrary wave forms, e.g., for dual-frequency discharges. The model calculates explicitly the cubic correction parameter in the charge-voltage relation for the case of highly asymmetric discharges. It is shown that the cubic correction is generally moderate but more pronounced in the collisionless case. The analytical results are compared to experimental data from the literature obtained by laser electric field measurements of the mean and dynamic fields in the capacitive sheath for various gases and pressures. Very good agreement is found throughout.

Czarnetzki, Uwe

2013-12-01

344

Voltage verification unit  

DOEpatents

A voltage verification unit and method for determining the absence of potentially dangerous potentials within a power supply enclosure without Mode 2 work is disclosed. With this device and method, a qualified worker, following a relatively simple protocol that involves a function test (hot, cold, hot) of the voltage verification unit before Lock Out/Tag Out and, and once the Lock Out/Tag Out is completed, testing or "trying" by simply reading a display on the voltage verification unit can be accomplished without exposure of the operator to the interior of the voltage supply enclosure. According to a preferred embodiment, the voltage verification unit includes test leads to allow diagnostics with other meters, without the necessity of accessing potentially dangerous bus bars or the like.

Martin, Edward J. (Virginia Beach, VA)

2008-01-15

345

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

SciTech Connect

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

Peng, Fang Zheng [Tennessee Univ., Knoxville, TN (United States)]|[Oak Ridge National Lab., TN (United States); Lai, Jih-Sheng; McKeever, J.; VanCoevering, J. [Oak Ridge National Lab., TN (United States)

1995-09-01

346

Josephson device for voltage measurement  

NASA Astrophysics Data System (ADS)

This paper describes a new Josephson device with microwave integrated circuit for voltage standard. The circuit is essentially made of a resonator (Nb), the Josephson junction (Nb, NbOx, Pb-In) and a capacitive microstrip section (Pb-In) which ends the rf part; the dc connections are through Cauer Filters (Nb or Pb-In). A niobium film is deposited on the opposite side of the fused quartz substrate as a ground plane. The circuit is enclosed in a special package with outside dc and rf connections. The technology ensures very good cyclability and lifetime with storage at room temperature. In liquid helium (4.2 K) with a very weak rf power less than 0.5 milliwatts at the frequency resonance (11.5 GHz), 100 ? A high current steps were obtained near a polarization of 4.5 mV. These devices allows a precision of 1 × 10 -7 on the volt standard when used with a series-parallel divider of fixed value (ratio 225). The precise adjustment of the voltages is made by a slight drift of the rf frequency of the source, allowed by the high rf coupling factor of the device and the band width of its resonance.

Régent, A.; Villegier, J. C.; Angénieux, G.; Monllor, C.; Delahaye, F.

347

Single stage high voltage gain boost converter with voltage Multiplier Cells for battery charging using photovoltaic panels  

Microsoft Academic Search

This paper presents a non-isolated high frequency DC-DC converter, which integrates a battery charger, photovoltaic panels, and a high voltage gain boost converter in a single conversion stage with soft-switching characteristic. The proposed topology uses voltage Multiplier Cells (MCs), leading do high voltage step-up. Also, the bidirectional behavior admits the DC bus to be generated via battery bank, or photovoltaic

Luiz H. S. C. Barreto; Paulo P. Praca; Gustavo A. L. Henn; Ranoyca N. A. L. Silva; Demercil S. Oliveira

2012-01-01

348

Calibration of the ISOLDE acceleration voltage using a high-precision voltage divider and applying collinear fast beam laser spectroscopy  

Microsoft Academic Search

A high-voltage divider with accuracy at the ppm level and collinear laser spectroscopy were used to calibrate the high-voltage installation at the radioactive ion beam facility ISOLDE at CERN. The accurate knowledge of this voltage is particularly important for collinear laser spectroscopy measurements. Beam velocity measurements using frequency-comb based collinear laser spectroscopy agree with the new calibration. Applying this, one

A. Krieger; Ch. Geppert; R. Catherall; F. Hochschulz; J. Krämer; R. Neugart; S. Rosendahl; J. Schipper; E. Siesling; Ch. Weinheimer; D. T. Yordanov; W. Nörtershäuser

2011-01-01

349

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

SciTech Connect

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

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

2009-01-01

350

Dynamic voltage scaling on a low-power microprocessor  

Microsoft Academic Search

Power consumption is the limiting factor for the functionality of future wearable devices. Since interactive applications like wireless information access generate bursts of activities, it is important to match the performance of the wearable device accordingly. This paper describes a system with a microprocessor whose speed can be varied (frequency scaling) as well as its supply voltage. Voltage scaling is

Johan A. Pouwelse; Koen Langendoen; Henk J. Sips

2001-01-01

351

A vector control technique for medium voltage multilevel inverters  

Microsoft Academic Search

This paper presents a switching strategy for multilevel cascade inverters, based on the space vector theory. The proposed switching strategy generates a voltage vector with very low harmonic distortion and reduced switching frequency. This new control method is an attractive alternative to the classic multilevel PWM techniques considering the following aspects: (i) voltage and current THD, (ii) range of linear

J. Rodriguez; P. Correa; L. Moran

2001-01-01

352

Voltage space vector based PWM control of forced commutated cycloconverters  

Microsoft Academic Search

A PWM (pulse-width modulation) control technique of forced commutated cycloconverters (FCCs), based on the space vector representation of the voltages in the complex plane, is considered. Output voltage and input current waveforms are analyzed in the time and frequency domains. The approach used in the analysis is valid for all practical cases of the digital implementation of the proposed FCC

L. Huber; D. Borojevic; N. Burany

1989-01-01

353

A vector control technique for medium-voltage multilevel inverters  

Microsoft Academic Search

This paper presents a switching strategy for multilevel cascade inverters, based on the space-vector theory. The proposed switching strategy generates a voltage vector with very low harmonic distortion and reduced switching frequency. This new control method is an attractive alternative to the classic multilevel pulsewidth modulation techniques considering the following aspects: (1) voltage and current total harmonic distortion; (2) range

José Rodríguez; Luis Morán; Pablo Correa; Cesar Silva

2002-01-01

354

High frequency inverter-cycloconverter system for dc to ac conversion  

Microsoft Academic Search

A high frequency inverter-cycloconverter system for dc to ac conversion was studied. The primary stage produces a high frequency square wave (500 Hz) which is reduced to a lower frequency (50 Hz) by a cycloconverter which applies a sinusoidally weighted phase controlled technique to produce a pwm-like output. The modulation strategy is presented and harmonic analysis of the positive, negative

M. R. D. Al-Mothafar

1987-01-01

355

Single Event Transients in Low Voltage Dropout (LVDO) Voltage Regulators  

NASA Technical Reports Server (NTRS)

This viewgraph presentation reviews the use of Low Voltage Dropout (LVDO) Voltage Regulators in environments where heavy ion induced Single Event Transients are a concern to the designers.Included in the presentation are results of tests of voltage regulators.

LaBel, K.; Karsh, J.; Pursley, S.; Kleyner, I.; Katz, R.; Poivey, C.; Kim, H.; Seidleck, C.

2006-01-01

356

Low voltage to high voltage level shifter and related methods  

NASA Technical Reports Server (NTRS)

A shifter circuit comprises a high and low voltage buffer stages and an output buffer stage. The high voltage buffer stage comprises multiple transistors arranged in a transistor stack having a plurality of intermediate nodes connecting individual transistors along the stack. The transistor stack is connected between a voltage level being shifted to and an input voltage. An inverter of this stage comprises multiple inputs and an output. Inverter inputs are connected to a respective intermediate node of the transistor stack. The low voltage buffer stage has an input connected to the input voltage and an output, and is operably connected to the high voltage buffer stage. The low voltage buffer stage is connected between a voltage level being shifted away from and a lower voltage. The output buffer stage is driven by the outputs of the high voltage buffer stage inverter and the low voltage buffer stage.

Mentze, Erik J. (Inventor); Hess, Herbert L. (Inventor); Buck, Kevin M. (Inventor); Cox, David F. (Inventor)

2006-01-01

357

Strongly nonlinear dynamics of electrolytes in large ac voltages  

E-print Network

We study the response of a model microelectrochemical cell to a large ac voltage of frequency comparable to the inverse cell relaxation time. To bring out the basic physics, we consider the simplest possible model of a ...

Hojgaard Olesen, Laurits

358

A Digital PFC Controller without Input Voltage Sensing  

E-print Network

to Fig. 1, in a PFC rectifier the current control objective can be written as: ig= VgIRe, where vg is the rectified line voltage, ig is the low-frequency (average) component of the inductor current, and Re

359

Silicon-Germanium Voltage-Controlled Oscillator at 105 GHz  

NASA Technical Reports Server (NTRS)

A group at UCLA, in collaboration with the Jet Propulsion Laboratory, has designed a voltage-controlled oscillator (VCO) created specifically for a compact, integrated, electronically tunable frequency generator useable for submillimeter- wave science instruments operating in extreme cold environments.

Wong, Alden; Larocca, Tim; Chang, M. Frank; Samoska, Lorene A.

2011-01-01

360

Pulse-shape effects on frequency chirping in single-frequency semiconductor lasers under current modulation  

Microsoft Academic Search

Directly modulated semiconductor lasers exhibit dynamic frequency shifts (chirping) due to gain-induced variations of the refractive index. Using the small-signal analysis of the single-mode rate equations, the effect of current-pulse shape on frequency chirping is analyzed, and the results are compared for the cases of sinusoidal and square-wave modulations. The chirp is generally larger for the square-wave case. However, its

T. Shen; G. Agrawal

1986-01-01

361

Array-projected aperiodic sinusoidal fringes for high-speed 3-D shape measurement  

NASA Astrophysics Data System (ADS)

In recent years, the demands on three-dimensional (3-D) measurement systems have been getting higher, es- pecially concerning their speed. The use of a 3-D array projector enables measurement frame rates of up to the 100-kHz range. Our contribution introduces a new purpose-built setup that projects aperiodic sinusoidal fringes. We explain the 3-D measurement principle and the basic design of a 3-D array projector and describe the method how the desired aperiodic sinusoidal fringes are generated. We verify the consistency between specified and projected patterns and point out the results of the setups's characterization, e.g., of its high-speed capability. Furthermore, first 3-D shape measurements at a projection frame rate of 3 kHz resulting in a 3-D frame rate of <330 Hz are presented and evaluated.

Heist, Stefan; Mann, Andreas; Kühmstedt, Peter; Schreiber, Peter; Notni, Gunther

2014-05-01

362

SNDR enhancement in noisy sinusoidal signals by non-linear processing elements  

NASA Astrophysics Data System (ADS)

We investigate the possibility of building linear amplifiers capable of enhancing the Signal-to-Noise and Distortion Ratio (SNDR) of sinusoidal input signals using simple non-linear elements. Other works have proven that it is possible to enhance the Signal-to-Noise Ratio (SNR) by using limiters. In this work we study a soft limiter non-linear element with and without hysteresis. We show that the SNDR of sinusoidal signals can be enhanced by 0.94 dB using a wideband soft limiter and up to 9.68 dB using a wideband soft limiter with hysteresis. These results indicate that linear amplifiers could be constructed using non-linear circuits with hysteresis. This paper presents mathematical descriptions for the non-linear elements using statistical parameters. Using these models, the input-output SNDR enhancement is obtained by optimizing the non-linear transfer function parameters to maximize the output SNDR.

Martorell, Ferran; McDonnell, Mark D.; Abbott, Derek; Rubio, Antonio

2007-06-01

363

Derivation of the sinusoidal sweep vibration test levels for the Cosmic Background Explorer (COBE)  

NASA Technical Reports Server (NTRS)

The Cosmic Background Explorer (COBE) Observatory was successfully launched on November 18, 1989 using a Delta l expendable launch vehicle. Prior to launch, COBE was subjected to sinusoidal sweep vibration testing in each of three axes in the 15 Hz to 40 Hz region. The tests were used to qualify COBE for the sustained periodic oscillation events that were expected to occur in flight for the Delta l launch vehicle. These events were called pre-MECO (Main Engine Cutoff) POGO and MECO-POGO. Pre-MECO POGO is also commonly called mini-POGO. This paper will describe the process used to derive the sinusoidal sweep test levels and will present a comparison of the actual COBE flight data versus the derived test levels. The results show that the derived test levels were sufficient to encompass the levels measured in flight for the COBE mission.

Coladonato, Robert J.

1991-01-01

364

Derivation of the sinusoidal sweep vibration test levels for the Cosmic Background Explorer (COBE)  

NASA Astrophysics Data System (ADS)

The Cosmic Background Explorer (COBE) Observatory was successfully launched on November 18, 1989 using a Delta l expendable launch vehicle. Prior to launch, COBE was subjected to sinusoidal sweep vibration testing in each of three axes in the 15 Hz to 40 Hz region. The tests were used to qualify COBE for the sustained periodic oscillation events that were expected to occur in flight for the Delta l launch vehicle. These events were called pre-MECO (Main Engine Cutoff) POGO and MECO-POGO. Pre-MECO POGO is also commonly called mini-POGO. This paper will describe the process used to derive the sinusoidal sweep test levels and will present a comparison of the actual COBE flight data versus the derived test levels. The results show that the derived test levels were sufficient to encompass the levels measured in flight for the COBE mission.

Coladonato, Robert J.

365

Bone marrow long label-retaining cells reside in the sinusoidal hypoxic niche  

SciTech Connect

In response to changing signals, quiescent hematopoietic stem cells (HSCs) can be induced to an activated cycling state and provide multi-lineage hematopoietic cells to the whole body via blood vessels. However, the precise localization of quiescent HSCs in bone marrow microenvironment is not fully characterized. Here, we performed whole-mount immunostaining of bone marrow and found that BrdU label-retaining cells (LRCs) definitively reside in the sinusoidal hypoxic zone distant from the 'vascular niche'. Although LRCs expressed very low level of a well-known HSC marker, c-kit in normal circumstances, myeloablation by 5-FU treatment caused LRCs to abundantly express c-kit and proliferate actively. These results demonstrate that bone marrow LRCs reside in the sinusoidal hypoxic niche, and function as a regenerative cell pool of HSCs.

Kubota, Yoshiaki; Takubo, Keiyo [Department of Cell Differentiation, Sakaguchi Laboratory, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582 (Japan); Suda, Toshio [Department of Cell Differentiation, The Sakaguchi Laboratory, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582 (Japan)], E-mail: sudato@sc.itc.keio.ac.jp

2008-02-08

366

[Auditory steady-state response to sinusoidally amplitude-modulated tones. Second report: investigation of response in the sleeping state].  

PubMed

The auditory steady state response (SSR) elicited by a sinusoidally amplitude-modulated (SAM) tone may be an important technique in objective audiometry, which provides frequency-specific information. This response is affected the state of arousal of the subject. An effect of sleep on the amplitude of this response has been observed by a number of previous investigators. Since young children must usually be sedated to carry out evoked potential testing, the effects of sleep on this response are a crucial factor limiting clinical applicability. The basic characteristics of SSR elicited by a 500 Hz SAM tone were studied in 21 adults with normal hearing during sleep. The responses while sleeping were compared with the responses in the awake state. The responses to 2048 stimuli were averaged with the analysis time set at 102.4 ms, and responses were judged by passing the waveforms through a 20-100 Hz digital filter. The same technique was performed in 25 infants (2 months-2 years 9 months) evaluated as having normal hearing. The results obtained are summarized as follows: The amplitude of the response while sleeping was approximately half the amplitude in the awake state. Responses with a modulation frequency of 70Hz, however, showed a persistent decrease in 71.0%, suggesting a trend different from that seen at a modulation frequency of less than 70Hz. The effect of modulation frequency on response amplitude was almost the same for the sleeping state and the awake state. Even during sleep, the response amplitude was maximal at modulation frequencies of 20, 30 and 40Hz, and there was no significant difference between the values at 20Hz -40Hz. The latency of the response was measured by the Diamond method, and the results showed that latency is significantly prolonged while sleeping (p < 0.01). The response threshold at the 500Hz SAM tone (modulation rate 40Hz, modulation depth 90%) was 8.5dBnHL when awake and 13.9dBnHL during sleep. The rise in threshold as a result of sleep was no more than about 5dB. In infants, the response amplitude at a modulation frequency of 20Hz was maximal, and amplitude at the 40Hz was significantly smaller (p < 0.01). Latency measured by the Diamond method in infants was 12.8ms. Thus, a difference from the response in adults was confirmed. Comparisons were made between the responses of infants under 1 year of age and infants over 1 year of age to confirm changes in response according to age. PMID:7738707

Umegaki, Y

1995-03-01

367

Voltage balanced multilevel voltage source converter system  

SciTech Connect

Disclosed is a voltage balanced multilevel converter for high power AC applications such as adjustable speed motor drives and back-to-back DC intertie of adjacent power systems. This converter provides a multilevel rectifier, a multilevel inverter, and a DC link between the rectifier and the inverter allowing voltage balancing between each of the voltage levels within the multilevel converter. The rectifier is equipped with at least one phase leg and a source input node for each of the phases. The rectifier is further equipped with a plurality of rectifier DC output nodes. The inverter is equipped with at least one phase leg and a load output node for each of the phases. The inverter is further equipped with a plurality of inverter DC input nodes. The DC link is equipped with a plurality of rectifier charging means and a plurality of inverter discharging means. The plurality of rectifier charging means are connected in series with one of the rectifier charging means disposed between and connected in an operable relationship with each adjacent pair of rectifier DC output nodes. The plurality of inverter discharging means are connected in series with one of the inverter discharging means disposed between and connected in an operable relationship with each adjacent pair of inverter DC input nodes. Each of said rectifier DC output nodes are individually electrically connected to the respective inverter DC input nodes. By this means, each of the rectifier DC output nodes and each of the inverter DC input nodes are voltage balanced by the respective charging and discharging of the rectifier charging means and the inverter discharging means. 15 figs.

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

1997-07-01

368

Voltage balanced multilevel voltage source converter system  

DOEpatents

A voltage balanced multilevel converter for high power AC applications such as adjustable speed motor drives and back-to-back DC intertie of adjacent power systems. This converter provides a multilevel rectifier, a multilevel inverter, and a DC link between the rectifier and the inverter allowing voltage balancing between each of the voltage levels within the multilevel converter. The rectifier is equipped with at least one phase leg and a source input node for each of the phases. The rectifier is further equipped with a plurality of rectifier DC output nodes. The inverter is equipped with at least one phase leg and a load output node for each of the phases. The inverter is further equipped with a plurality of inverter DC input nodes. The DC link is equipped with a plurality of rectifier charging means and a plurality of inverter discharging means. The plurality of rectifier charging means are connected in series with one of the rectifier charging means disposed between and connected in an operable relationship with each adjacent pair of rectifier DC output nodes. The plurality of inverter discharging means are connected in series with one of the inverter discharging means disposed between and connected in an operable relationship with each adjacent pair of inverter DC input nodes. Each of said rectifier DC output nodes are individually electrically connected to the respective inverter DC input nodes. By this means, each of the rectifier DC output nodes and each of the inverter DC input nodes are voltage balanced by the respective charging and discharging of the rectifier charging means and the inverter discharging means.

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

1997-01-01

369

Generating Electrical Voltage  

NSDL National Science Digital Library

Teachers' Domain presents this interactive lesson designed to help students "learn how a generator converts mechanical energy into electrical energy. Investigate the principle of magnetic induction by moving a conductor through a magnetic field to see how voltage is generated." The lesson is divided into three major sections: How Do Generators Work?, What Factors Influence Voltage Strength?, and What Determines Voltage Polarity? There are plenty of animations to help students visualize the processes at work in electricity generation. On the site, visitors will also find a supplemental background essay, discussion questions, and standards alignment from Teachers' Domain.

370

Nonpulsed sinusoidal electromagnetic fields as a noninvasive strategy in bone repair: the effect on human mesenchymal stem cell osteogenic differentiation.  

PubMed

In vivo control of osteoblast differentiation is an important process needed to maintain the continuous supply of mature osteoblast cells for growth, repair, and remodeling of bones. The regulation of this process has also an important and significant impact on the clinical strategies and future applications of cell therapy. In this article, we studied the effect of nonpulsed sinusoidal electromagnetic field radiation tuned at calcium-ion cyclotron frequency of 50?Hz exposure treatment for bone differentiation of human mesenchymal stem cells (hMSCs) alone or in synergy with dexamethasone, their canonical chemical differentiation agent. Five days of continuous exposure to calcium-ion cyclotron resonance affect hMSC proliferation, morphology, and cytoskeletal actin reorganization. By quantitative real-time polymerase chain reaction, we also observed an increase of osteoblast differentiation marker expression such as Runx2, alkaline phosphatase (ALP), osteocalcin (OC), and osteopontin (OPN) together with the osteoprotegerin mRNA modulation. Moreover, in these cells, the increase of the protein expression of OPN and ALP was also demonstrated. These results demonstrate bone commitment of hMSCs through a noninvasive and biocompatible differentiating physical agent treatment and highlight possible applications in new regenerative medicine protocols. PMID:25087470

Ledda, Mario; D'Emilia, Enrico; Giuliani, Livio; Marchese, Rodolfo; Foletti, Alberto; Grimaldi, Settimio; Lisi, Antonella

2015-02-01

371

Effects of 60?Hz sinusoidal magnetic field on in vitro establishment, multiplication, and acclimatization phases of Coffea arabica seedlings.  

PubMed

The influence of extremely low frequency electromagnetic fields on net photosynthesis, transpiration, photosynthetic pigment concentration, and gene expression of ribulose 1,5-bisphosphate carboxylase/oxygenase small subunit (RBCS1), during in vitro establishment, in vitro multiplication and acclimatization phases of coffee seedlings were investigated. Untreated coffee plants were considered as control, whereas treated plants were exposed to a 60?Hz sinusoidal magnetic field of 2?mT of magnetic induction during 3?min. This magnetic field was generated by an electromagnet, connected to a wave generator. The results revealed that magnetically treated plants showed a significant increase in net photosynthesis (85.4% and 117.9%, in multiplication and acclimatization phases, respectively), and in photosynthetic pigment concentration (66.6% for establishment phase, 79.9% for multiplication phase, and 43.8% for acclimatization phase). They also showed a differential RBCS1 gene expression (approximately twofold) and a decrease of transpiration rates in regard to their control plants. In conclusion, the findings suggest that the application of 60?Hz magnetic field to in vitro coffee plants may improve the seedlings quality by modifying some photosynthetic physiological and molecular processes, increasing their vigor, and ensuring better plant development in later stages. PMID:25043829

Isaac Alemán, Elizabeth; Oliveira Moreira, Rafael; Almeida Lima, Andre; Chaves Silva, Samuel; González-Olmedo, Justo Lorenzo; Chalfun-Junior, Antonio

2014-09-01

372

Indirect measurement of dynamic force transmitted by a nonlinear hydraulic mount under sinusoidal excitation with focus on super-harmonics  

NASA Astrophysics Data System (ADS)

Direct measurement of forces is not practical in many real-life applications since the interfacial conditions may change. Thus indirect force estimation methods must be developed though they pose special difficulty for nonlinear mounts or isolators. The hydraulic engine mount is examined as an illustrative example in this article since it exhibits spectrally varying and amplitude-sensitive parameters. First, we propose linear time-invariant, nonlinear and quasi-linear fluid and mechanical system models. Second, models are utilized to predict the transmitted force time history under sinusoidal excitation conditions given measured (or calculated) motion and/or internal pressure time histories. Experimental data from the non-resonant dynamic stiffness test is investigated in both time and frequency domains. In particular, the super-harmonic contents in fluid chamber pressure and force time histories are investigated using both measurements and mathematical models. This paper examines several alternate indirect schemes for estimating dynamic forces and highlights their strengths. The quasi-linear model with effective system parameters, say in terms of force to pressure or force to motion transfer functions, is found to correlate well with measured dynamic forces though linear and nonlinear models could be employed as well.

Yoon, Jong-Yun; Singh, Rajendra

2010-12-01

373

Mechanisms of Xenogeneic Baboon Platelet Aggregation and Phagocytosis by Porcine Liver Sinusoidal Endothelial Cells  

PubMed Central

Background Baboons receiving xenogeneic livers from wild type and transgenic pigs survive less than 10 days. One of the major issues is the early development of profound thrombocytopenia that results in fatal hemorrhage. Histological examination of xenotransplanted livers has shown baboon platelet activation, phagocytosis and sequestration within the sinusoids. In order to study the mechanisms of platelet consumption in liver xenotransplantation, we have developed an in vitro system to examine the interaction between pig endothelial cells with baboon platelets and to thereby identify molecular mechanisms and therapies. Methods Fresh pig hepatocytes, liver sinusoidal and aortic endothelial cells were isolated by collagenase digestion of livers and processing of aortae from GTKO and Gal+ MGH-miniature swine. These primary cell cultures were then tested for the differential ability to induce baboon or pig platelet aggregation. Phagocytosis was evaluated by direct observation of CFSE labeled-platelets, which are incubated with endothelial cells under confocal light microscopy. Aurintricarboxylic acid (GpIb antagonist blocking interactions with von Willebrand factor/vWF), eptifibatide (Gp IIb/IIIa antagonist), and anti-Mac-1 Ab (anti-?M?2 integrin Ab) were tested for the ability to inhibit phagocytosis. Results None of the pig cells induced aggregation or phagocytosis of porcine platelets. However, pig hepatocytes, liver sinusoidal and aortic endothelial cells (GTKO and Gal+) all induced moderate aggregation of baboon platelets. Importantly, pig liver sinusoidal endothelial cells efficiently phagocytosed baboon platelets, while pig aortic endothelial cells and hepatocytes had minimal effects on platelet numbers. Anti-MAC-1 Ab, aurintricarboxylic acid or eptifibatide, significantly decreased baboon platelet phagocytosis by pig liver endothelial cells (P<0.01). Conclusions Although pig hepatocytes and aortic endothelial cells directly caused aggregation of baboon platelets, only pig liver endothelial cells efficiently phagocytosed baboon platelets. Blocking vWF and integrin adhesion pathways prevented both aggregation and phagocytosis. PMID:23118867

Peng, Qiang; Yeh, Heidi; Wei, Lingling; Enjyoj, Keiichi; Machaidze, Zurab; Csizmad, Eva; Schuetz, Christian; Lee, Kang Mi; Deng, Shaoping; Robson, Simon C.; Markmann, James; Buhler, Leo

2012-01-01

374

Improved sinusoidal gating with balanced InGaAs/InP Single Photon Avalanche Diodes.  

PubMed

We report balanced InGaAs/InP single photon avalanche diodes (SPADs) operated in sinusoidal gating mode with a tunable phase shifter to reduce common mode noise. This technique enables detection of small avalanche pulses, which results in reduced afterpulsing. For laser repletion rate of 20 MHz at 240 K, the dark count rate for photon detection efficiency of 10% is 8.9 kHz. PMID:23938523

Lu, Zhiwen; Sun, Wenlu; Zhou, Qiugui; Campbell, Joe; Jiang, Xudong; Itzler, Mark A

2013-07-15

375

Highly enhanced avalanche probability using sinusoidally-gated silicon avalanche photodiode  

SciTech Connect

We report on visible light single photon detection using a sinusoidally-gated silicon avalanche photodiode. Detection efficiency of 70.6% was achieved at a wavelength of 520?nm when an electrically cooled silicon avalanche photodiode with a quantum efficiency of 72.4% was used, which implies that a photo-excited single charge carrier in a silicon avalanche photodiode can trigger a detectable avalanche (charge) signal with a probability of 97.6%.

Suzuki, Shingo; Namekata, Naoto, E-mail: nnao@phys.cst.nihon-u.ac.jp; Inoue, Shuichiro [Institute of Quantum Science, Nihon University, 1-8-14 Kanda-Surugadai, Chiyoda-ku, Tokyo 101-8308 (Japan); Tsujino, Kenji [Tokyo Women's Medical University, 8-1 Kawada-cho, Shinjuku-ku, Tokyo 162-8666 (Japan)

2014-01-27

376

Direct Torque Control of Brushless DC Motor with Non-sinusoidal Back-EMF  

Microsoft Academic Search

In this paper, a direct torque control (DTC) technique for brushless dc (BLDC) motors with non-sinusoidal back-EMF operating in the constant torque region is presented. This approach introduces a two-phase conduction mode as opposed to the conventional three-phase DTC drives. In this control scheme, only two phases conduct at any instant of time. Unlike conventional six-step PWM current control, by

Salih Baris Ozturk; H. A. Toliyat

2007-01-01

377

15th International Symposium on Cells of the Hepatic Sinusoid, 2010  

PubMed Central

This is a meeting report of the presentations given at the 15th International Symposium on Cells of the Hepatic Sinusoid, held in 2010. The areas covered include the contributions of the various liver cell populations to liver disease, molecular and cellular targets involved in steatohepatitis, hepatic fibrosis and cancer and regenerative medicine. In addition to a review of the science presented at the meeting, this report provides references to recent literature on the topics covered at the meeting. PMID:21645207

DeLeve, Laurie D.; Jaeschke, Hartmut; Kalra, Vijay K.; Asahina, Kinji; Brenner, David A.; Tsukamoto, Hidekazu

2015-01-01

378

LTI representations of adaptive systems with tap delay-line regressors under sinusoidal excitation  

Microsoft Academic Search

It is shown that an adaptive system whose regressor is formed by tap delay-line (TDL) filtering of a multitone sinusoidal signal is representable as a parallel connection of a linear time-invariant (LTI) block and a linear time-varying (LTV) block. The induced 2-norm of the LTV subsystem decreases as N-1 where N is the number of taps. Hence the adaptive system

David S. Bayard

1997-01-01

379

Design considerations of sinusoidally excited permanent-magnet Machines for low-torque-ripple applications  

Microsoft Academic Search

Several high-performance motor drive applications require the motor drive to produce smooth torque with very stringent torque-ripple requirement. This paper is focused on various machine design considerations that can be used in reducing the torque ripple of a sinusoidally excited permanent-magnet brushless dc motor. The paper quantifies the various sources of torque ripple, which may be minimized by appropriate design

Mohammad S. Islam; Sayeed Mir; Tomy Sebastian; Samuel Underwood

2005-01-01

380

Pitch estimation and voicing detection based on a sinusoidal speech model  

Microsoft Academic Search

A technique for estimating the pitch of a speech waveform is developed. It fits a harmonic set of sine waves to the input data using a mean-squared-error (MSE) criterion. By exploiting a sinusoidal model for the input speech waveform, a pitch estimation criterion is derived that is inherently unambiguous, uses pitch-adaptive resolution, uses small-signal suppression to provide enhanced discrimination, and

Robert J. McAulay; Thomas F. Quatieri

1990-01-01

381

Surface separation and contact resistance considering sinusoidal elastic–plastic multi-scale rough surface contact  

Microsoft Academic Search

The current work considers the multi-scale nature of surface roughness in a new model that predicts the real area of contact and surface separation as functions of load. This work is based upon a previous rough surface multi-scale contact model which used stacked elastic–plastic spheres to model the multiple scales of roughness. Instead, this work uses stacked 3D sinusoids to

W. Everett Wilson; Santosh V. Angadi; Robert L. Jackson

2010-01-01

382

Bright versus dark schlieren imaging: quantitative analysis of quasi-sinusoidal phase objects  

Microsoft Academic Search

We discuss the schlieren imaging of quasi-sinusoidal phase objects. We demonstrate that, when the zero-order (Fourier) spatial component of the input image is not blocked by the schlieren-knife at the Fourier plane, the intensity distribution on the reconstructed image is a linear function of the phase amplitude. In contrast, if the zero order is completely blocked (i.e., dark Schlieren processing),

Ismael Núñez; José A. Ferrari

2007-01-01

383

Effects of reactor type and voltage properties in methanol reforming with nonthermal plasma  

Microsoft Academic Search

Reactor type and voltage properties affected the reforming behavior of 1% methanol in N2 with nonthermal plasma. Methanol conversion increased with voltage frequency for both a ferroelectric packed-bed reactor (FPR) and a silent discharge reactor (SDR), but they showed different sensitivities to frequency change at fixed applied voltages. In the frequency range of 5 Hz-5 kHz, methanol conversion was expressed

Shigeru Futamura; Hajime Kabashima

2004-01-01

384

Multigigahertz voltage-controlled oscillators in advanced silicon bipolar technology  

Microsoft Academic Search

Relaxation-type monolithic silicon bipolar voltage-controlled oscillators (VCOs) with center frequencies ranging from 1.5 to 5 GHz are described. The maximum oscillating frequency achieved is 7.4 GHz. The VCOs dissipate about 70 mW from a 3.6-V supply, including the output buffer and voltage-to-current converter stages. Two types of on-chip timing capacitor structure and various configurations used in achieving these results are

Mehmet Soyuer; James D. Warnock

1992-01-01

385

High voltage DC power supply  

DOEpatents

A high voltage DC power supply having a first series resistor at the output for limiting current in the event of a short-circuited output, a second series resistor for sensing the magnitude of output current, and a voltage divider circuit for providing a source of feedback voltage for use in voltage regulation is disclosed. The voltage divider circuit is coupled to the second series resistor so as to compensate the feedback voltage for a voltage drop across the first series resistor. The power supply also includes a pulse-width modulated control circuit, having dual clock signals, which is responsive to both the feedback voltage and a command voltage, and also includes voltage and current measuring circuits responsive to the feedback voltage and the voltage developed across the second series resistor respectively. 7 figs.

Droege, T.F.

1989-12-19

386

High voltage DC power supply  

DOEpatents

A high voltage DC power supply having a first series resistor at the output for limiting current in the event of a short-circuited output, a second series resistor for sensing the magnitude of output current, and a voltage divider circuit for providing a source of feedback voltage for use in voltage regulation is disclosed. The voltage divider circuit is coupled to the second series resistor so as to compensate the feedback voltage for a voltage drop across the first series resistor. The power supply also includes a pulse-width modulated control circuit, having dual clock signals, which is responsive to both the feedback voltage and a command voltage, and also includes voltage and current measuring circuits responsive to the feedback voltage and the voltage developed across the second series resistor respectively.

Droege, Thomas F. (Batavia, IL)

1989-01-01

387

Array projection of aperiodic sinusoidal fringes for high-speed three-dimensional shape measurement  

NASA Astrophysics Data System (ADS)

Three-dimensional (3-D) measurement systems based on coded-light techniques are conventionally limited by the projection speed, which is typically in the range of a few 100 Hz, resulting in 3-D frame rates of 1 to 60 Hz. We propose to use an array projector for 3-D shape measurements, which enables much higher projection frame rates of up to the 100-kHz range. In contrast to previous setups, it does not project well-known phase-shifted sinusoidal fringes and Gray code patterns, but aperiodic sinusoidal fringes. This new technique, based on sine-shaped fringes with spatially and temporally varying offset, amplitude, period length, and phase shift, allows accurate 3-D measurement of objects, even with sharp edges, high slope, or varying surface properties, at high speed up to the kilohertz range. This paper explains the 3-D measurement principle and the basic design of an array projector that projects aperiodic sinusoidal fringes. It verifies the consistency between specified and projected patterns and points out the results of the setup's characterization, e.g., of its high-speed capability. Furthermore, first 3-D shape measurements at a projection frame rate of 3 kHz resulting in a 3-D frame rate of >330 Hz are presented and evaluated.

Heist, Stefan; Mann, Andreas; Kühmstedt, Peter; Schreiber, Peter; Notni, Gunther

2014-11-01

388

High Voltage Solar Array  

NASA Astrophysics Data System (ADS)

In order to manage gigantic power of SSPS (Space Solar Power System) efficiently, use of extreme high voltage is necessary unless we minimize the transmission distance by employing a sandwich type of generator/transmitter panel. For 1 GW-class SSPS, the power transmission/generation voltage of 10 kV is necessary to keep the cable mass below a few hundred tons. To realize high voltage photovoltaic power generation, arcing caused by environmental interaction must be overcome. Three issues are reviewed. The first is degradation of solar cell performance due to repetitive arcing resulted from surface charging in GEO. The second is sustained arc phenomenon that may lead to catastrophic loss of significant portion of the total power. The third is micrometeoroid or space debris impact and resulting sustained arc. A design of high voltage solar array is proposed to prevent solar cell degradation due to repeated trigger arcs and sustained arc.

Cho, Mengu

389

Improving membrane voltage measurements  

E-print Network

as fluorescence resonance energy transfer (FRET) donor and acceptor to develop a voltage sensor, named Mermaid activities in cultured excitable cells. Notably, Mermaid has fast on-off kinetics at warm (B33 1C

Cai, Long

390

High Voltage TAL Performance  

NASA Technical Reports Server (NTRS)

The performance of a two-stage, anode layer Hall thruster was evaluated. Experiments were conducted in single and two-stage configurations. In single-stage configuration, the thruster was operated with discharge voltages ranging from 300 to 1700 V. Discharge specific impulses ranged from 1630 to 4140 sec. Thruster investigations were conducted with input power ranging from 1 to 8.7 kW, corresponding to power throttling of nearly 9: 1. An extensive two-stage performance map was generated. Data taken with total voltage (sum of discharge and accelerating voltage) constant revealed a decrease in thruster efficiency as the discharge voltage was increased. Anode specific impulse values were comparable in the single and two-stage configurations showing no strong advantage for two-stage operation.

Jacobson, David T.; Jankovsky, Robert S.; Rawlin, Vincent K.; Manzella, David H.

2001-01-01

391

Josephson voltage standards  

Microsoft Academic Search

This paper reviews the present state of modern Josephson voltage standards. The presentation focuses on conventional dc standards based on underdamped superconductor-insulator-superconductor junctions and programmable standards based on overdamped superconductor-insulator-normal conductor-insulator-superconductor junctions. The current developments of ac standards on the basis of pulse-driven arrays and single flux quantum-based voltage multipliers are briefly summarized.

Johannes Kohlmann; Ralf Behr; Torsten Funck

2003-01-01

392

The effect of voltage waveform and tube diameter on transporting cold plasma strings through a flexible dielectric tube  

NASA Astrophysics Data System (ADS)

In this work, we developed transporting atmospheric pressure cold plasma using single electrode configuration through a sub-millimetre flexible dielectric tube beyond 100 cm. It was shown that the waveform of the applied high voltage is essential for controlling upstream and downstream plasma inside the tube. In this regard, sawtooth waveform enabled the transport of plasma with less applied high voltage compared to sinusoidal and pulsed form voltages. A cold plasma string as long as 130 cm was obtained by only 4 kV peak-to-peak sawtooth high voltage waveform. Optical emission spectroscopy revealed that reactive chemical species, such as atomic oxygen and hydroxyl, are generated at the tube exit. The effect of tube diameter on the transported plasma was also examined: the smaller the diameter, the higher the applied voltage. The device is likely to be used for sterilization, decontamination, and therapeutic endoscopy as already suggested by other groups in recent past years.

Sohbatzadeh, Farshad; Omran, Azadeh Valinataj

2014-11-01

393

Optimal condition of memristance enhancement circuit using external voltage source  

NASA Astrophysics Data System (ADS)

Memristor provides nonlinear response in the current-voltage characteristic and the memristance is modulated using an external voltage source. We point out by solving nonlinear equations that an optimal condition of the external voltage source exists for maximizing the memristance in such modulation scheme. We introduce a linear function to describe the nonlinear time response and derive an important design guideline; a constant ratio of the frequency to the amplitude of the external voltage source maximizes the memristance. The analysis completely accounts for the memristance behavior.

Tanaka, Hiroya; Tadokoro, Yukihiro; Iizuka, Hideo

2014-05-01

394

A frequency shift keying transmitter based on incoherent frequency-to-time mapping for free-space optical communications  

Microsoft Academic Search

A novel frequency shift keying (FSK) transmitter for free-space optical communications based on incoherent frequency-to-time mapping is proposed and demonstrated. In the proposed system, an incoherent broadband optical source is spectrally shaped by an optical filter that has a sinusoidal frequency response and a tunable free spectral range (FSR), and then modulated at a temporal gate. The temporally gated optical

Hongqian Mu; Haiyun Xia; Jianping Yao

2010-01-01

395

A simple and self-adapting high-performance current control scheme for three phase voltage source inverters  

Microsoft Academic Search

An adaptive optimized regulator (AOR) for three-phase voltage source inverters is presented. The zero-voltage vectors are used systematically to reduce the switching frequency and can be reached by switching only one inverter leg. In the steady stage the controller applies to the machine only those three voltage vectors which are directly adjacent to the machine voltage (similar to pulse width

Ansgar Ackva; Harry Reinold; Reniigiusz Olesinski

1992-01-01

396

PHONETIC PERCEPTION OF SINUSOIDAL SIGNALS: EFFECTS OF AMPLITUDE VARIATION* Robert E. Remez,+ Philip E. Rubin, and Thomas D. Carrell++  

E-print Network

PHONETIC PERCEPTION OF SINUSOIDAL SIGNALS: EFFECTS OF AMPLITUDE VARIATION* Robert E. Remez,+ Philip, are capable of transcribing the phonetic message of acoustic signals consisting solely of time stimulus. Phonetic and syllabic intelligibility were compared in four conditions: (1) normal amplitude

397

Device for monitoring cell voltage  

DOEpatents

A device for monitoring a rechargeable battery having a number of electrically connected cells includes at least one current interruption switch for interrupting current flowing through at least one associated cell and a plurality of monitoring units for detecting cell voltage. Each monitoring unit is associated with a single cell and includes a reference voltage unit for producing a defined reference threshold voltage and a voltage comparison unit for comparing the reference threshold voltage with a partial cell voltage of the associated cell. The reference voltage unit is electrically supplied from the cell voltage of the associated cell. The voltage comparison unit is coupled to the at least one current interruption switch for interrupting the current of at least the current flowing through the associated cell, with a defined minimum difference between the reference threshold voltage and the partial cell voltage.

Doepke, Matthias (Garbsen, DE); Eisermann, Henning (Edermissen, DE)

2012-08-21

398

On-machine measurement of a cylindrical surface with sinusoidal micro-structures by an optical slope sensor  

Microsoft Academic Search

This paper describes the measurement of a cylindrical surface with sinusoidal micro-structures over a large area on a diamond turning machine. The sinusoidal micro-structures, which are fabricated on the periphery surface of a cylinder by the fast tool servo-based diamond turning, are superposition of periodic sine-waves along the cylinder axis and the cylinder circumference with amplitudes of 100nm and wavelengths

Wei Gao; Makoto Tano; Shinji Sato; Satoshi Kiyono

2006-01-01

399

Surface profile measurement of a sinusoidal grid using an atomic force microscope on a diamond turning machine  

Microsoft Academic Search

This paper describes the surface profile measurement of a XY-grid workpiece with sinusoidal microstructures using an atomic force microscope (AFM) on a diamond turning machine. The sinusoidal micro-structures, which are fabricated on an aluminum plate by fast tool servo-assisted diamond turning, are a superposition of periodic sine-waves along the X- and Y-directions (wavelength (XY): 150?m, amplitude (Z): 0.25?m). A linear

Wei Gao; Jun Aoki; Bing-Feng Ju; Satoshi Kiyono

2007-01-01

400

Power quality assessment in electrical utilities including distributed generation unit & hybrid filters under non-ideal source voltage  

Microsoft Academic Search

This paper deals with a hybrid compensation system in electrical utility including a distributed generation (DG) unit under non-ideal source voltages condition. The DG unit consists of a Solid Oxide Fuel Cell (SOFC) as active power source and a three-phase full-bridge DC-AC inverter for power conversion. DG unit is controlled to deliver balanced and sinusoidal current in phase with fundamental

S. H. Hosseini; T. Nouri

2011-01-01

401

Multistage Estimation Of Frequency And Phase  

NASA Technical Reports Server (NTRS)

Conceptual two-stage software scheme serves as prototype of multistage scheme for digital estimation of phase, frequency, and rate of change of frequency ("Doppler rate") of possibly phase-modulated received sinusoidal signal in communication system in which transmitter and/or receiver traveling rapidly, accelerating, and/or jerking severely. Each additional stage of multistage scheme provides increasingly refined estimate of frequency and phase of signal. Conceived for use in estimating parameters of signals from spacecraft and high dynamic GPS signal parameters, also applicable, to terrestrial stationary/mobile (e.g., cellular radio) and land-mobile/satellite communication systems.

Kumar, Rajendra

1991-01-01

402

Current vs. Voltage Feedback Amplifiers  

E-print Network

is a voltage source that is controlled by the potential difference between the two input terminals voltage to zero, hence the term voltage feedback. Gain Bandwidth Product Refer to the non-inverting gainCurrent vs. Voltage Feedback Amplifiers One question continuously troubles the analog design engi

Lanterman, Aaron

403

High voltage variable diameter insulator  

DOEpatents

A high voltage feedthrough assembly having a tubular insulator extending between the ground plane ring and the high voltage ring. The insulator is made of Pyrex and decreases in diameter from the ground plane ring to the high voltage ring, producing equipotential lines almost perpendicular to the wall of the insulator to optimize the voltage-holding capability of the feedthrough assembly.

Vanacek, D.L.; Pike, C.D.

1982-07-13

404

Optimal Design of Repetitive Controller for Harmonic Elimination in PWM Voltage Source  

E-print Network

Optimal Design of Repetitive Controller for Harmonic Elimination in PWM Voltage Source Inverters voltage source inverter systems. A method of analyzing the repetitive control system from the frequency The pulse-width modulation (PWM) voltage source inverter (VSI) is extensively employed in AC power

Tse, Chi K. "Michael"

405

A fast and accurate single frequency estimator  

Microsoft Academic Search

A novel frequency estimator for a single complex sinusoid in complex white Gaussian noise is proposed. The estimator is more computationally efficient that the optimal maximum-likelihood estimator yet attains equally good performance at moderately high signal-to-noise ratios. The estimator is shown to be related to the linear prediction estimator. This relationship is used to reveal why the linear prediction estimator

STEVEN KAY

1989-01-01

406

Encoding frequency contrast in primate auditory cortex.  

PubMed

Changes in amplitude and frequency jointly determine much of the communicative significance of complex acoustic signals, including human speech. We have previously described responses of neurons in the core auditory cortex of awake rhesus macaques to sinusoidal amplitude modulation (SAM) signals. Here we report a complementary study of sinusoidal frequency modulation (SFM) in the same neurons. Responses to SFM were analogous to SAM responses in that changes in multiple parameters defining SFM stimuli (e.g., modulation frequency, modulation depth, carrier frequency) were robustly encoded in the temporal dynamics of the spike trains. For example, changes in the carrier frequency produced highly reproducible changes in shapes of the modulation period histogram, consistent with the notion that the instantaneous probability of discharge mirrors the moment-by-moment spectrum at low modulation rates. The upper limit for phase locking was similar across SAM and SFM within neurons, suggesting shared biophysical constraints on temporal processing. Using spike train classification methods, we found that neural thresholds for modulation depth discrimination are typically far lower than would be predicted from frequency tuning to static tones. This "dynamic hyperacuity" suggests a substantial central enhancement of the neural representation of frequency changes relative to the auditory periphery. Spike timing information was superior to average rate information when discriminating among SFM signals, and even when discriminating among static tones varying in frequency. This finding held even when differences in total spike count across stimuli were normalized, indicating both the primacy and generality of temporal response dynamics in cortical auditory processing. PMID:24598525

Malone, Brian J; Scott, Brian H; Semple, Malcolm N

2014-06-01

407

Electro-optic control of a PPLN-unpoled LiNbO3 boundary for low-voltage Q switching of an intracavity frequency-doubled Nd3+:YVO4 laser.  

PubMed

We present a simple technique to integrate an electro-optic Q switch in a periodically poled bulk lithium niobate crystal bounded by two unpoled (monodomain) regions. The technique exploits the high sensitivity to low applied electric fields of the total internal reflection condition in the periodic poled-unpoled boundary for the small grazing incidence angles associated with the diffraction of a focused Gaussian beam that propagates in the periodically poled region with its axis parallel to the boundary. When the arrangement is placed intracavity to a 1064 nm diode-pumped Nd(3+):YVO(4) laser, it performs simultaneously as a Q switch and as a second-harmonic generator, with Q switching starting at applied voltages as low as 1 V over a 500 microm thickness and with no additional optical elements. PMID:19649073

Torregrosa, A J; Maestre, H; Fernández-Pousa, C R; Pereda, J A; Capmany, J

2009-08-01

408

High voltage coaxial switch  

DOEpatents

A coaxial high voltage, high current switch having a solid cylindrical cold cathode coaxially surrounded by a thin hollow cylindrical inner electrode and a larger hollow cylindrical outer electrode. A high voltage trigger between the cathode and the inner electrode causes electrons to be emitted from the cathode and flow to the inner electrode preferably through a vacuum. Some of the electrons penetrate the inner electrode and cause a volumetric discharge in the gas (which may be merely air) between the inner and outer electrodes. The discharge provides a low impedance path between a high voltage charge placed on the outer electrode and a load (which may be a high power laser) coupled to the inner electrode. For high repetition rate the gas between the inner and outer electrodes may be continuously exchanged or refreshed under pressure.

Rink, John P. (Los Alamos, NM)

1983-07-19

409

High voltage coaxial switch  

DOEpatents

A coaxial high voltage, high current switch having a solid cylindrical cold cathode coaxially surrounded by a thin hollow cylindrical inner electrode and a larger hollow cylindrical outer electrode. A high voltage trigger between the cathode and the inner electrode causes electrons to be emitted from the cathode and flow to the inner electrode preferably through a vacuum. Some of the electrons penetrate the inner electrode and cause a volumetric discharge in the gas (which may be merely air) between the inner and outer electrodes. The discharge provides a low impedance path between a high voltage charge placed on the outer electrode and a load (which may be a high power laser) coupled to the inner electrode. For high repetition rate the gas between the inner and outer electrodes may be continuously exchanged or refreshed under pressure. 3 figs.

Rink, J.P.

1983-07-19

410

Electron launching voltage monitor  

DOEpatents

An electron launching voltage monitor measures MITL voltage using a relationship between anode electric field and electron current launched from a cathode-mounted perturbation. An electron launching probe extends through and is spaced from the edge of an opening in a first MITL conductor, one end of the launching probe being in the gap between the MITL conductor, the other end being adjacent a first side of the first conductor away from the second conductor. A housing surrounds the launching probe and electrically connects the first side of the first conductor to the other end of the launching probe. A detector detects the current passing through the housing to the launching probe, the detected current being representative of the voltage between the conductors. 5 figs.

Mendel, C.W.; Savage, M.E.

1992-03-17

411

Expression of MMP-9 in hepatic sinusoidal obstruction syndrome induced by Gynura segetum *  

PubMed Central

Background and objective: Hepatic sinusoidal obstruction syndrome (HSOS) is characterized by painful hepatomegaly, ascites, increased body weight, and jaundice. Gynura segetum (Compositae), a plant widely used in Chinese traditional medicine, often leads to the development of HSOS. However, the mechanism is unclear. The aim was to study the role of matrix metalloproteinase-9 (MMP-9) in the onset of HSOS induced by Gynura segetum. Methods: Twenty-five male Sprague-Dawley rats were randomly divided into two groups. Twenty were exposed to 600 mg/kg daily Gynura segetum extract solution for three weeks; five control rats were exposed to tap water alone. Liver sections were evaluated by light microscopy with a modified scoring system. Routine transmission electron microscopy (TEM) methods were used to evaluate the ultrastructual features of fixed liver tissue, and blood samples were collected to determine liver enzyme concentrations. MMP-9 expression was assessed by both immunohistochemical staining and enzyme-linked immunosorbent assay (ELISA) methods. Results: A stable and reproducible rat model of HSOS was achieved by long-term exposure to Gynura segetum extract. The treated rats presented clinical symptoms and the histopathological manifestation of HSOS, including abnormal liver enzyme concentrations (alanine aminotransferase (ALT): (84.8±13.62) vs. (167.0±72.63) U/L, P<0.05; aspartate aminotransferase (AST): (27.6±6.31) vs. (232.8±108.58) U/L, P<0.05). Hematoxylin and eosin (H&E) staining and TEM together revealed deposition of red blood cells, the damage and destruction of hepatic sinusoidal endothelial cells, collapse of hepatic sinusoids, hemorrhage of subendothelial cells, atrophy and destruction of hepatocytes, etc. Compared with controls, the expression of MMP-9 in the blood sample, the lung and liver tissues of HSOS rats was increased. Conclusions: MMP-9 may have an important role in early pathological changes of HSOS, and thus the onset of the disease. PMID:23303633

Yu, Xia-zhen; Ji, Tao; Bai, Xue-li; Liang, Liang; Wang, Lin-yan; Chen, Wei; Liang, Ting-bo

2013-01-01

412

Lightning induced voltages on power lines: experiment  

SciTech Connect

The authors present correlated measurements of the voltage induced on a power line by nearby lightning and the vertical electric field intensity from that lightning. Data are given for more than 100 first strokes and more than 200 subsequent strokes with the lightning ground strike point located by triangulation using a network of television cameras and by thunder ranging. Voltages were measured at one end of a 460 m unenergized distribution line which was open-circuited at both ends. A neutral wire was located beneath the line and was grounded at both ends. The time-domain voltage and vertical electric field waveforms were detected and recorded on a system having a frequency response from less than 1 Hz to over 1 MHz. Only about half of the voltage wave forms resemble the ''classical induced positive surges'' described in the literature. The magnitude and polarity of the peak induced voltage is a strong function of the location of the lightning ground strike point.

Master, M.J.; Beasley, W.; Darveniza, M.; Uman, M.A.

1984-09-01

413

A voltage-mode DC—DC buck converter with fast output voltage-tracking speed and wide output voltage range  

NASA Astrophysics Data System (ADS)

A high switching frequency voltage-mode buck converter with fast voltage-tracking speed and wide output voltage range has been proposed. A novel error amplifier (EA) is presented to achieve a high DC gain and get high phase margin, including a resistor and capacitor net, a unit gain block and a high gain block. The investigated converter has been fabricated with GF 0.35 ?m CMOS process and can operate at 6 MHz with the output voltage range from 0.6 to 3.4 V. The experimental results show that the voltage-tracking speed can achieve 8.8 ?s/V for up-tracking and 6 ?s/V for down-tracking. Besides, the recovery time is less than 8 ?s while the load current suddenly changes 400 mA.

Miao, Yang; Baixue, Zhang; Yun, Cao; Fengfeng, Sun; Weifeng, Sun

2014-05-01

414

Alterations in liver sinusoidal endothelium in a baboon model of type 1 diabetes  

Microsoft Academic Search

Aims\\/hypothesis  Diabetes mellitus is associated with extensive vascular pathology, yet little is known about its long-term effects on liver\\u000a sinusoidal endothelial cells (LSECs). Potential diabetic changes in LSECs are important because of the role played by fenestrations\\u000a in the LSECs in hepatic disposition of lipoproteins.\\u000a \\u000a \\u000a \\u000a Materials and methods  Surgical liver biopsies for electron microscopy and immunohistochemistry were obtained from baboons with long-standing

H. A. Jamieson; V. C. Cogger; S. M. Twigg; S. V. McLennan; A. Warren; R. Cheluvappa; S. N. Hilmer; R. Fraser; R. de Cabo; D. G. Le Couteur

2007-01-01

415

Natural convection in an inclined square enclosure subject to sinusoidal temperature profile  

NASA Astrophysics Data System (ADS)

A numerical study on natural convection in an inclined square enclosure with sinusoidal temperature profile on the left wall is considered, while the right wall is kept with constant temperature. The horizontal walls of the enclosure are adiabatic. The governing equations are solved by using the finite difference method for different Rayleigh numbers and inclination angles. The results are provided in the form of streamlines, isotherms and Nusselt numbers. The flow patterns are dependent on Rayleigh numbers and inclination angles. The heat transfer increases first and then decreases with increasing the inclination of the enclosure.

Cheong, H. T.; Siri, Z.; Sivasankaran, S.

2013-04-01

416

Efficacy of an AC sinusoidal electric field for apoptosis induction in lung carcinoma cells (A549)  

NASA Astrophysics Data System (ADS)

An AC sinusoidal electric field was applied to lung carcinoma cells for the induction of apoptosis. The occurrence of apoptosis was determined by analysis of Annexin V/PI and DNA fragmentation. Additional evidence of apoptosis was confirmed by caspase-3 cleavage and disruption of mitochondrial membrane potential. These results demonstrated that the expression of apoptosis can be controlled by varying the magnitude and the duration of the field, and that the application of an AC electric field can stimulate the apoptosis via mitochondria-mediated pathway.

Park, Hyoun-Hyang; Lee, Seung S.; Hoon Lee, Dae

2012-08-01

417

Simple method for the estimation of power losses in silicon iron sheets under alternating pulse voltage excitation  

NASA Astrophysics Data System (ADS)

The prediction of iron losses in magnetic steels submitted to alternating pulse voltages is studied and an efficient method is proposed. It is developed by coupling the pulse voltage form factor and the loss separation model. Prediction of iron losses becomes possible directly from the loss model corresponding to the sinusoidal flux density. This method is validated on silicon iron grain-oriented and non-oriented magnetic steels. The predetermined iron losses are coherent with those measured and this approach allows both simplicity and precision well appreciated by industry.

Amar, M.; Protat, F.

1994-03-01

418

Journal of ELECTRONIC MATERIALS, Vol. 33, No. 10, 2004 Regular Issue Paper Capacitance-Voltage Characterization of Pulsed Plasma  

E-print Network

-Voltage Characterization of Pulsed Plasma Polymerized Allylamine Dielectrics for Flexible Polymeric Field Effect frequency (RF) pulsed plasma polymerization (PPP), were employed as insulating layers of metal- insulator for flexible devices. #12;Capacitance-Voltage Characterization of Pulsed Plasma Polymerized Allylamine

419

Reproductive hazards among workers at high voltage substations  

Microsoft Academic Search

A retrospective study on reproductive hazards was performed among 542 employees at Swedish power plants. Questionnaires were answered by 89% of the employees. Data on pregnancies were checked by studying hospital case records. There was a statistically significant, decreased frequency of ''normal'' pregnancy outcome, almost exclusively due to an increased frequency of congenital malformations, when the father was a high-voltage

S. Nordstroem; E. Birke; L. Gustavsson

1983-01-01

420

A dynamic voltage scaled microprocessor system  

Microsoft Academic Search

Abstract—A microprocessor system is presented in which the supply voltage and clock frequency can be dynamically varied so that the system can deliver high throughput when required while significantly extending battery life during the low speed periods. The system consists of a dc-dc switching regulator, an ARM V4 microprocessor with a 16-kB cache, a bank of 64-kB SRAM ICs, and

Thomas D. Burd; Trevor A. Pering; Anthony J. Stratakos; Robert W. Brodersen

2000-01-01

421

An improved high-voltage waveform generator  

Microsoft Academic Search

An improved high-voltage low-frequency waveform generator is described. It is based on a design by Miller et al. (1975) with the addition of a feedback control loop. The device can supply up to 27 kV and 2 mA from 0-100 Hz, and up to 10 kV at 1 kHz. Total harmonic distortion is reduced from the earlier device to under

P. T. Krein; D. J. Kervin; J. M. Crowley

1983-01-01

422

Species differences in sinusoidal and canalicular efflux transport of mycophenolic acid 7-O-glucuronide in sandwich-cultured hepatocytes  

PubMed Central

Metabolism and sinusoidal/canalicular efflux of mycophenolic acid (MPA) was investigated using sandwich-cultured hepatocytes (SCHs). After applying MPA to SCHs from humans, wild-type rats, and multidrug resistance-associated protein (Mrp) 2-deficient rats, the MPA metabolites 7-O-glucuronide (MPAG) and acyl glucuronide (AcMPAG) were detected in the intracellular compartment of the SCHs. Sinusoidal efflux of MPAG was detected in all SCH preparations including Mrp2-deficient rat SCHs, whereas canalicular efflux of MPAG was observed in wild-type rat and human SCHs but not in Mrp2-deficient rat SCHs. The ratio of canalicular efflux to net (canalicular plus sinusoidal) efflux was 37 ± 8% in wild-type rat SCHs, while the ratio in human SCHs was significantly lower (20 ± 2%, P < 0.05), indicating species differences in the direction of hepatic MPAG transport. This 20% ratio in human SCHs corresponds to a high sinusoidal MPAG efflux (80%) that can in part account for the urine-dominated recovery of MPAG in humans. Both sinusoidal and canalicular MPAG efflux in rat SCHs shows a good correspondence to urinary and biliary recovery of MPAG after MPA dosing. The sinusoidal efflux of AcMPAG in human SCHs was detected from one out of three donors, suggesting donor-to-donor variation. In conclusion, this study demonstrates the predictive value of SCHs for elucidating the interplay of metabolism and efflux transport, in addition to demonstrating a species difference between rat and human in sinusoidal and canalicular efflux of MPAG. PMID:25505584

Tetsuka, Kazuhiro; Gerst, Nicolas; Tamura, Kouichi; Masters, Jeffrey N

2014-01-01

423

Voltage-Controlled Oscillator  

NASA Technical Reports Server (NTRS)

Integrated Component Systems, Inc. incorporated information from a NASA Tech Briefs article into a voltage-controlled oscillator it designed for a customer. The company then applied the technology to its series of phase-locked loop synthesizers, which offer superior phase noise performance.

1995-01-01

424

Insulators for high voltages  

Microsoft Academic Search

This book describes electrical insulators for high voltage applications. Topics considered include the insulating materials, the manufacture of wet process porcelain, the manufacture of tempered glass, the glass-fibre core, the polymeric housing, the common problem - terminating an insulator, mechanical constraints, the physics of pollution flashover, the physics of contamination, testing of insulators, conclusions from testing, remedies for flashover, insulators

Looms; J. S. T

1987-01-01

425

Geomagnetism and Induced Voltage  

ERIC Educational Resources Information Center

Introductory physics laboratories have seen an influx of "conceptual integrated science" over time in their classrooms with elements of other sciences such as chemistry, biology, Earth science, and astronomy. We describe a laboratory to introduce this development, as it attracts attention to the voltage induced in the human brain as it is…

Abdul-Razzaq, W.; Biller, R. D.

2010-01-01

426

Reduction of voltage stress in the full bridge BIBRED by duty ratio and phase shift control  

Microsoft Academic Search

A new control scheme is presented which provides simultaneous control of the output voltage and the energy storage capacitor voltage in the full-bridge boost integrated with buck rectifier\\/energy storage\\/DC-DC power converter (full-bridge BIBRED). The new control scheme solves the problem of wide voltage excursions for the energy storage capacitor voltage under variable load conditions. A low frequency, large signal AC

M. A. Johnston; R. W. Erickson

1994-01-01

427

Development of Automatic Voltage Regulator for Low Voltage Distribution Systems  

NASA Astrophysics Data System (ADS)

This paper presents the development of a new type of voltage regulator that can adequately maintain the voltage supplied to customers, dealing with the problem of voltage control along with the widespread use of photovoltaic power generation systems. The developed equipment is a pole-mounted type voltage regulator consisting of a step-down transformer that converts voltage from high to low and a series transformer for voltage compensation. The demonstration test conducted at the CRIEPI Akagi Test Center confirmed that the voltage control function of the developed voltage regulator is satisfactory based on the proposed control algorism. Also, simulation analysis, on the assumption of the clustered installation of photovoltaic power generation systems, confirmed that the introduction of the developed voltage regulator enables the system voltage to be adequately maintained and full photovoltaic power generation is possible without suppressing the output. It is anticipated that the developed voltage regulator is very effective in adequately regulating the voltage for low voltage distribution systems and gives an effective way for even more widespread photovoltaic power generation.

Matsuda, Katsuhiro; Horikoshi, Kazuhiro; Seto, Toshiyuki; Iyama, Osamu; Kobayashi, Hiromu

428

LIVER GRAFT EXPOSURE TO CARBON MONOXIDE DURING COLD STORAGE PROTECTS SINUSOIDAL ENDOTHELIAL CELLS AND AMELIORATES REPERFUSION INJURY IN RATS  

PubMed Central

Background Hepatic ischemia/reperfusion (I/R) injury significantly influences short and long-term outcomes after liver transplantation (LTx). The critical step initiating the injury is known to include sinusoidal endothelial cell (SEC) alteration during the cold preservation period. As carbon monoxide (CO) has potent cytoprotective functions on vascular endothelial cells, this study examines if CO treatment of excised liver grafts during cold storage could protect SEC and ameliorate hepatic I/R injury. Methods Rat liver grafts were preserved in UW solution containing 5% CO (CO-UW) for 18–24 hrs and transplanted into syngenic Lewis rats. Results After 18 hrs cold preservation, SEC damage was evident with Propidium Iodide (PI) nuclear stain on SEC, and the frequency of PI+ SEC was significantly lower in grafts stored in CO-UW than in control UW. SEC protection with CO associated with decreased ICAM translocation and less MMP release during cold preservation. After LTx with 18 hrs cold preservation, serum ALT levels and hepatic necrosis were significantly less in CO-UW than in control UW group. With 24 hrs cold storage, 35% (7/20) survived with control UW, while the survival with CO-UW improved to 80% (8/10). These beneficial effects of CO-UW associated with significant reduction of neutrophil extravasation, down-regulation of hepatic mRNA for TNF-? and ICAM-1, and less hepatic ERK activation. Liver grafts from Kupffer cell depleted donors or pseudogerm-free donors showed less SEC death during cold preservation, and CO-UW further reduced SEC death. Conclusion CO delivery to excised liver grafts during cold preservation efficiently ameliorates SEC damage and hepatic I/R injury. PMID:19877256

Ikeda, Atsushi; Ueki, Shinya; Nakao, Atsunori; Tomiyama, Koji; Ross, Mark A.; Stolz, Donna B.; Geller, David A.; Murase, Noriko

2010-01-01

429

Adaptive spectral analysis technique for unbiased frequency estimation in the presence of white noise  

Microsoft Academic Search

An adaptive spectral analysis technique is presented for estimating the frequencies of sinusoids corrupted by white noise. This new method is an on-line implementation of a harmonic-retrieval method proposed by Pisarenko involving the minimum eigenvalue and the associated eigenvector of the covariance matrix. This eigenvector, whose components translate into frequency estimates, is sought adaptively (without explicitly evaluating the covariance matrix)

P. A. Thompson

1979-01-01

430

Improved detection of electrical activity with a voltage probe based on a voltage-sensing phosphatase  

PubMed Central

One of the most awaited techniques in modern physiology is the sensitive detection of spatiotemporal electrical activity in a complex network of excitable cells. The use of genetically encoded voltage probes has been expected to enable such analysis. However, in spite of recent progress, existing probes still suffer from low signal amplitude and/or kinetics too slow to detect fast electrical activity. Here, we have developed an improved voltage probe named Mermaid2, which is based on the voltage-sensor domain of the voltage-sensing phosphatase from Ciona intestinalis and Förster energy transfer between a pair of fluorescent proteins. In mammalian cells, Mermaid2 permits ratiometric readouts of fractional changes of more than 50% over a physiologically relevant voltage range with fast kinetics, and it was used to follow a train of action potentials at frequencies of up to 150 Hz. Mermaid2 was also able to detect single action potentials and subthreshold voltage responses in hippocampal neurons in vitro, in addition to cortical electrical activity evoked by sound stimuli in single trials in living mice. PMID:23836686

Tsutsui, Hidekazu; Jinno, Yuka; Tomita, Akiko; Niino, Yusuke; Yamada, Yoshiyuki; Mikoshiba, Katsuhiko; Miyawaki, Atsushi; Okamura, Yasushi

2013-01-01

431

Sinusoidal wavy surfaces for curvature-guided migration of T lymphocytes.  

PubMed

Micro/nanofabricated surfaces have been widely used for the study of topography-guided migration of cells. While the current studies mostly utilized micro/nanostructures containing sharp edges, internal tissues guiding migration of cells such as blood and lymphatic vessels, bone cavities, perivascular tracks have smooth microscale topographical structures. To overcome these limitations, we fabricated sinusoidal wavy surfaces with various wavelengths by deep X-ray lithography enabling precise and simultaneous control of amplitudes and wavelengths. Using these surfaces, we systematically studied curvature-guided migration of T cells. The majority of T cells migrated along the concave surfaces of sinusoidal wavy structures and as wavelength increased (or curvature decreased), preference to concave surfaces decreased. Integrin-mediated adhesion augmented the tendency of T cells crawling along grooves of highly curved wavy surfaces. To understand mechanisms of curvature-guided migration of T cells, T cells were treated with small molecule drugs such as blebbistatin and CK636, inhibiting myosin II activity and lamellipodia formation, respectively. While lamellipodia-inhibited T cells frequently crossed ridges, myosin II-inhibited T cells were mostly confined within concave surfaces. These results suggest that lamellipodia regulate local actin polymerization in response to surface curvature to maintain T cells within concave surfaces while myosin II-mediated contractile forces push T cells out of concave surfaces to make T cells less sensitive to surface curvature. PMID:25771006

Song, Kwang Hoon; Park, Sung Jea; Kim, Dong Sung; Doh, Junsang

2015-05-01

432

Vibration insensitive interferometer using sinusoidal phase-modulation and feedback control  

NASA Astrophysics Data System (ADS)

It is easy to extract a signal proportional to a phase fluctuation from a sinusoidally phase-modulated interference signal. This fluctuation is caused by mechanical vibration or air turbulence. In a sinusoidal phase-modulating interferometer using a laser diode (LD) the phase fluctuation is reduced by changing the injection current of the LD with a feedback control system. This control is very useful to a Fizeau type interferometer for surface profile measurement of a large size object. IC wafers of 100 mm diameter are measured with an interferometer insensitive to mechanical vibration and air turbulence. The phase fluctuation with nearly constant amplitude which corresponds to 30nm in surface height is reduced by about 10%. However the reduction in the phase fluctuation is not performed well for an instantaneous and large phase fluctuation. In order to be insensitive to all kinds of phase fluctuations the feedback signal is always observed, so that the interference signal is captured when the amplitude of the feedback signal is less than a specified level during the capturing time of 0.53 s. Thus surface profiles of the IC wafers can be measured with a high repeatability of a few nm even when any kind of vibration exists.

Sasaki, Osami; Iwai, Hidetaka; Suzuki, Takamasa

2005-12-01

433

Calibration-free sinusoidal rectification and uniform retinal irradiance in scanning light ophthalmoscopy.  

PubMed

Sinusoidal rectification (i.e., desinusoiding) is necessary for scanning imaging systems and is typically achieved by calculating a rectification transform from a calibration image such as a regular grid. This approach is susceptible to error due to electronic or mechanical instability that can alter the phase of the imaging window with respect to the calibration transform. Here, we show a calibration-free rectification method implemented from live video of a scanning light ophthalmoscope (SLO) with or without adaptive optics (AO). This approach, which capitalizes on positional differences in the images obtained in the forward and backward scan directions, dynamically keeps the imaging window in phase with the motion of the sinusoidal resonant scanner, preventing errors from signal drift over time. A benefit of this approach is that it allows the light power across the field-of-view (FOV) to be modulated inversely to achieve uniform irradiance on the retina, a feature desirable for functional imaging methods and light safety in SLOs. PMID:25531615

Yang, Qiang; Yin, Lu; Nozato, Koji; Zhang, Jie; Saito, Kenichi; Merigan, William H; Williams, David R; Rossi, Ethan A

2015-01-01

434

Vestibular modulation of muscle sympathetic nerve activity during sinusoidal linear acceleration in supine humans  

PubMed Central

The utricle and saccular components of the vestibular apparatus preferentially detect linear displacements of the head in the horizontal and vertical planes, respectively. We previously showed that sinusoidal linear acceleration in the horizontal plane of seated humans causes a pronounced modulation of muscle sympathetic nerve activity (MSNA), supporting a significant role for the utricular component of the otolithic organs in the control of blood pressure. Here we tested the hypothesis that the saccule can also play a role in blood pressure regulation by modulating lower limb MSNA. Oligounitary MSNA was recorded via tungsten microelectrodes inserted into the common peroneal nerve in 12 subjects, laying supine on a motorized platform with the head aligned with the longitudinal axis of the body. Slow sinusoidal linear accelerations-decelerations (peak acceleration ±4 mG) were applied in the rostrocaudal axis (which predominantly stimulates the saccule) and in the mediolateral axis (which also engages the utricle) at 0.08 Hz. The modulation of MSNA in the rostrocaudal axis (29.4 ± 3.4%) was similar to that in the mediolateral axis (32.0 ± 3.9%), and comparable to that obtained by stimulation of the utricle alone in seated subjects with the head vertical. We conclude that both the saccular and utricular components of the otolithic organs play a role in the control of arterial pressure during postural challenges. PMID:25346657

Hammam, Elie; Bolton, Philip S.; Kwok, Kenny; Macefield, Vaughan G.

2014-01-01

435

A Novel Modular Bioreactor to In Vitro Study the Hepatic Sinusoid  

PubMed Central

We describe a unique, versatile bioreactor consisting of two plates and a modified commercial porous membrane suitable for in vitro analysis of the liver sinusoid. The modular bioreactor allows i) excellent control of the cell seeding process; ii) cell culture under controlled shear stress stimulus, and; iii) individual analysis of each cell type upon completion of the experiment. The advantages of the bioreactor detailed here are derived from the modification of a commercial porous membrane with an elastomeric wall specifically moulded in order to define the cell culture area, to act as a gasket that will fit into the bioreactor, and to provide improved mechanical robustness. The device presented herein has been designed to simulate the in vivo organization of a liver sinusoid and tested by co-culturing endothelial cells (EC) and hepatic stellate cells (HSC). The results show both an optimal morphology of the endothelial cells as well as an improvement in the phenotype of stellate cells, most probably due to paracrine factors released from endothelial cells. This device is proposed as a versatile, easy-to-use co-culture system that can be applied to biomedical research of vascular systems, including the liver. PMID:25375141

Illa, Xavi; Vila, Sergi; Yeste, Jose; Peralta, Carmen; Gracia-Sancho, Jordi; Villa, Rosa

2014-01-01

436

The Relationship between Fenestrations, Sieve Plates and Rafts in Liver Sinusoidal Endothelial Cells  

PubMed Central

Fenestrations are transcellular pores in endothelial cells that facilitate transfer of substrates between blood and the extravascular compartment. In order to understand the regulation and formation of fenestrations, the relationship between membrane rafts and fenestrations was investigated in liver sinusoidal endothelial cells where fenestrations are grouped into sieve plates. Three dimensional structured illumination microscopy, scanning electron microscopy, internal reflectance fluorescence microscopy and two-photon fluorescence microscopy were used to study liver sinusoidal endothelial cells isolated from mice. There was an inverse distribution between sieve plates and membrane rafts visualized by structured illumination microscopy and the fluorescent raft stain, Bodipy FL C5 ganglioside GM1. 7-ketocholesterol and/or cytochalasin D increased both fenestrations and lipid-disordered membrane, while Triton X-100 decreased both fenestrations and lipid-disordered membrane. The effects of cytochalasin D on fenestrations were abrogated by co-administration of Triton X-100, suggesting that actin disruption increases fenestrations by its effects on membrane rafts. Vascular endothelial growth factor (VEGF) depleted lipid-ordered membrane and increased fenestrations. The results are consistent with a sieve-raft interaction, where fenestrations form in non-raft lipid-disordered regions of endothelial cells once the membrane-stabilizing effects of actin cytoskeleton and membrane rafts are diminished. PMID:23029409

McNerney, Gregory P.; Owen, Dylan M.; Zencak, Dusan; Zykova, Svetlana N.; Crane, Harry; Huser, Thomas; Quinn, Ronald J.; Smedsrød, Bård; Le Couteur, David G.; Cogger, Victoria C.

2012-01-01

437

Vestibular modulation of muscle sympathetic nerve activity during sinusoidal linear acceleration in supine humans.  

PubMed

The utricle and saccular components of the vestibular apparatus preferentially detect linear displacements of the head in the horizontal and vertical planes, respectively. We previously showed that sinusoidal linear acceleration in the horizontal plane of seated humans causes a pronounced modulation of muscle sympathetic nerve activity (MSNA), supporting a significant role for the utricular component of the otolithic organs in the control of blood pressure. Here we tested the hypothesis that the saccule can also play a role in blood pressure regulation by modulating lower limb MSNA. Oligounitary MSNA was recorded via tungsten microelectrodes inserted into the common peroneal nerve in 12 subjects, laying supine on a motorized platform with the head aligned with the longitudinal axis of the body. Slow sinusoidal linear accelerations-decelerations (peak acceleration ±4 mG) were applied in the rostrocaudal axis (which predominantly stimulates the saccule) and in the mediolateral axis (which also engages the utricle) at 0.08 Hz. The modulation of MSNA in the rostrocaudal axis (29.4 ± 3.4%) was similar to that in the mediolateral axis (32.0 ± 3.9%), and comparable to that obtained by stimulation of the utricle alone in seated subjects with the head vertical. We conclude that both the saccular and utricular components of the otolithic organs play a role in the control of arterial pressure during postural challenges. PMID:25346657

Hammam, Elie; Bolton, Philip S; Kwok, Kenny; Macefield, Vaughan G

2014-01-01

438

Leakage current and common mode voltage issues in modern AC drive systems  

Microsoft Academic Search

Due to rapid developments of IGBT technology, switching time and frequency are dramatically increased. At higher carrier frequencies, IGBTs induce more capacitive coupled current into a rotor and a stator frame and lead to faster bearing damage. Common mode voltage enables motor to create shaft voltage through electrostatic couplings between the rotor and the stator windings and between the rotor

J. Adabi; F. Zare; G. Ledwich; A. Ghosh

2007-01-01

439

Voltage drop over a vacuum arc and the cathode-spot brightness  

SciTech Connect

A spectral investigation of low-current dc vacuum arc voltage is presented. High-speed steak photographs of cathode-spot light emission with high time resolution are obtained. Characteristic frequencies of cathode-spot instabilities are derived from averaged frequency spectra of arc voltage.

Nazarov, S.N.; Rakhovsky, V.I.; Zhurbenko, V.G. (All-Union Center for Surface and Vacuum Investigation, Andreevskaya Nab. 2, Moscow (SU))

1990-06-01

440

Effect of voltage waveform on partial discharge in ferroelectric pellet layer for gas cleaning  

Microsoft Academic Search

The effect of voltage waveform and frequency on a partial discharge in a ferroelectric pellet layer is experimentally studied. A description of the experimental apparatus is given. The capacitance of the pellet layer, the effect of frequency of the voltage on the partial discharge, and the effect of the dielectric constant (?s) value of the pellet on the partial discharge

Akira Mizuno; Yoshifumi Yamazaki; Sadami Obama; Eiki Suzuki; Ken Okazaki

1993-01-01

441

Spatial frequency dependence of accommodative responses in amblyopic eyes.  

PubMed

Monocular, steady-state accommodative responses were measured as a function of spatial frequency of simple sinusoidal gratings presented at high contrast and target vergence levels in amblyopes, as well as in strabismics without amblyopia and in visually-normal control subjects. In general, spatial frequency dependence of the accommodative response was the rule. However, the amblyopic eyes exhibited markedly reduced accommodative responses over most of the spatial frequency range tested, and this was attributed to reduced accommodative controller gain in the sensory pathways involved in the control of accommodation in the amblyopic eye. Due to the diversity of accommodative response spatial frequency profiles found across all groups, the results suggest that reflex, voluntary, and higher-level perceptual aspects of accommodation may interplay in a complex manner in the act of accommodation on a simple sinusoidal grating. PMID:6666060

Ciuffreda, K J; Hokoda, S C

1983-01-01

442

The membrane potential waveform of bursting pacemaker neurons is a predictor of their preferred frequency and the network cycle frequency  

PubMed Central

Many oscillatory networks involve neurons that exhibit intrinsic rhythmicity, but possess a large variety of voltage-gated currents which interact in a complex fashion making it difficult to determine which factors control frequency. Yet, these neurons often have preferred (resonance) frequencies that can be close to the network frequency. Because the preferred frequency results from the dynamics of ionic currents, it can be assumed to depend on parameters that determine the neuron’s oscillatory waveform shape. The pyloric network frequency in the crab Cancer borealis is correlated with the preferred frequency of its bursting pacemaker neurons AB and PD. We measure the preferred frequency of the PD neuron in voltage-clamp, which allows control of the oscillation voltage range and waveforms (sine waves and realistic oscillation waveforms), and showthat1) the preferred frequency depends on the voltage range of the oscillating voltage waveform; 2) the slope of the waveform near its peak has a strongly negative correlation with the preferred frequency; and 3) correlations between parameters of the PD neuron oscillation waveform and its preferred frequency can be used to predict shifts in the network frequency. As predicted by these results, dynamic clamp shifts of the upper or lower voltage limits of the PD neuron waveform during ongoing oscillations changed the network frequency, consistent with the predictions from the preferred frequency. These results show that the voltage waveform of oscillatory neurons can be predictive of their preferred frequency and thus the network oscillation frequency. PMID:20702710

Tseng, Hua-an; Nadim, Farzan

2010-01-01

443

HAPPE: Human and Application Driven Frequency Scaling for Processor Power  

E-print Network

and chip temperature, which affect performance, reliability, and lifetime. Processor power consumption, Robert P. Dick, Gokhan Memik, and Peter Dinda Abstract--Conventional dynamic voltage and frequency-and-application-aware dynamic CPU frequency scaling technique. HAPPE continuously adapts processor frequency and voltage

Dick, Robert

444

Zero-voltage switching technique in dc/dc converters  

NASA Astrophysics Data System (ADS)

A novel resonant switch operating under the principle of zero-voltage switching is presented. In contrast to the zero-current switching, this technique eliminates the switching loss and dv/dt noise due to the discharging of MOSFET junction capacitances and the reverse recovery of diodes, and enables the converters to operate at high frequencies. A dc analysis of the converter is carried out. The duality relationship between the zero-current switching technique and the zero-voltage switching technique is derived. The two techniques are compared using an example showing the duality between a current-mode quasi-resonant Buck converter and a voltage-mode quasi-resonant boost converter. A 5-MHz 50 V to 5 V flyback converter employing the zero-voltage switching technique has been implemented. The circuit contains the smallest number of components possible, and yet maintains high efficiency at high switching frequency.

Liu, Kwang-Hwa; Lee, Fred C. Y.

1990-07-01

445

A DC-AC Power Conversion Technique Using Twin Resonant High-Frequency Links  

Microsoft Academic Search

The advantages of load commUtated high-frequency (HF) sinusoidal inverters as link stiiges in power conversion are well-known. An inverter configuration that employs parallel connection of the load to the resonating capacitor can be employed to realize the high- frequency link. A technique of dc to low-frequency ac power conversion using two, such high-fre4uency links is presented. The frequencies of the

V. T. Ranganathan; Phoivos D. Ziogas

1983-01-01

446

SQUID voltage - controlled - oscillator  

SciTech Connect

The authors have investigated the SQUID as a voltage-controlled source of microwaves. The low impedance ''resistive'' SQUID can be a relatively high power (about nW), tunable, and monochromatic source for both on-chip and off-chip applications. Studies of the time-dependent junction phase and the available power spectra as they vary with such device parameters as loaded Q and the SQUID-BETA=2..pi..Li /SUB c/ //phi/ /SUB o/ establish design rules for a well-behaved oscillator. For a VCO BETA Q<2; for BETA Qgreater than or equal to2 degenerate parametric subharmonic oscillations and chaotic instabilities are observed. Power increase is suggested by the use of voltage-clamped dc SQUIDs and arrays.

Silver, A.; Sandell, R.; Wilcox, J.

1983-05-01

447

E-beam high voltage switching power supply  

DOEpatents

A high-power power supply produces a controllable, constant high voltage put under varying and arcing loads. The power supply includes a voltage regulator, an inductor, an inverter for producing a high frequency square wave current of alternating polarity, an improved inverter voltage clamping circuit, a step up transformer, an output rectifier for producing a dc voltage at the output of each module, and a current sensor for sensing output current. The power supply also provides dynamic response to varying loads by controlling the voltage regulator duty cycle and circuitry is provided for sensing incipient arc currents at the output of the power supply to simultaneously decouple the power supply circuitry from the arcing load. The power supply includes a plurality of discrete switching type dc--dc converter modules.

Shimer, Daniel W. (Danville, CA); Lange, Arnold C. (Livermore, CA)

1996-01-01

448

E-beam high voltage switching power supply  

DOEpatents

A high-power power supply produces a controllable, constant high voltage output under varying and arcing loads. The power supply includes a voltage regulator, an inductor, an inverter for producing a high frequency square wave current of alternating polarity, an improved inverter voltage clamping circuit, a step up transformer, an output rectifier for producing a dc voltage at the output of each module, and a current sensor for sensing output current. The power supply also provides dynamic response to varying loads by controlling the voltage regulator duty cycle and circuitry is provided for sensing incipient arc currents at the output of the power supply to simultaneously decouple the power supply circuitry from the arcing load. The power supply includes a plurality of discrete switching type dc--dc converter modules. 5 figs.

Shimer, D.W.; Lange, A.C.

1996-10-15

449

Growth mechanisms study of microcrystalline silicon deposited by SiH{sub 4}/H{sub 2} plasma using tailored voltage waveforms  

SciTech Connect

The use of Tailored Voltage Waveforms is a technique wherein one uses non-sinusoidal waveforms with a period equivalent to RF frequencies to excite a plasma. It has been shown to be an effective technique to decouple maximum Ion Bombardment Energy (IBE) from the ion flux at the surface of the electrodes. In this paper, we use it for the first time as a way to scan through the IBE in order to study the growth mechanism of hydrogenated microcrystalline silicon using a SiH{sub 4}/H{sub 2} chemistry. We find that at critical energies, a stepwise increase in the amorphous to microcrystalline transition thickness is observed, as detected by Real Time Spectroscopic Ellipsometry. The same energy thresholds (30?eV and 70?eV) are found to be very influential on the final surface morphology of the samples, as observed by Atomic Force Microscopy. These thresholds correspond to SiH{sub x}{sup +} bulk displacement (30?eV) and H{sub x}{sup +} (70?eV) surface displacement energies. A model is therefore proposed to account for the impact of these ions on the morphology of ?c-Si:H growth.

Bruneau, B., E-mail: bastien.bruneau@polytechnique.edu; Johnson, E. V. [LPICM-CNRS, Ecole Polytechnique, route de Saclay, 91128 Palaiseau (France); Wang, J. [LPICM-CNRS, Ecole Polytechnique, route de Saclay, 91128 Palaiseau (France); ICARE China-Europe Institute for Clean and Renewable Energy at Huazhong University of Science and Technology, 1037 Luoyu Road, 430074 Wuhan (China); Dornstetter, J.-C. [LPICM-CNRS, Ecole Polytechnique, route de Saclay, 91128 Palaiseau (France); TOTAL New Energies, 24 cours Michelet, 92069 Paris La Défense Cedex (France)

2014-02-28

450

Increased voltage photovoltaic cell  

NASA Technical Reports Server (NTRS)

A photovoltaic cell, such as a solar cell, is provided which has a higher output voltage than prior cells. The improved cell includes a substrate of doped silicon, a first layer of silicon disposed on the substrate and having opposite doping, and a second layer of silicon carbide disposed on the first layer. The silicon carbide preferably has the same type of doping as the first layer.

Ross, B.; Bickler, D. B.; Gallagher, B. D. (inventors)

1985-01-01

451

High voltage pulse conditioning  

DOEpatents

Apparatus for conditioning high voltage pulses from particle accelerators in order to shorten the rise times of the pulses. Flashover switches in the cathode stalk of the transmission line hold off conduction for a determinable period of time, reflecting the early portion of the pulses. Diodes upstream of the switches divert energy into the magnetic and electrostatic storage of the capacitance and inductance inherent to the transmission line until the switches close.

Springfield, Ray M. (Sante Fe, NM); Wheat, Jr., Robert M. (Los Alamos, NM)

1990-01-01

452

High voltage variable diameter insulator  

DOEpatents

A high voltage feedthrough assembly (10) having a tubular insulator (15) extending between the ground plane ring (16) and the high voltage ring (30). The insulator (15) is made of Pyrex and decreases in diameter from the ground plane ring (16) to the high voltage ring (30), producing equipotential lines almost perpendicular to the wall (27) of the insulator (15) to optimize the voltage-holding capability of the feedthrough assembly (10).

Vanecek, David L. (Martinez, CA); Pike, Chester D. (Pinole, CA)

1984-01-01

453

Age-related loss of responsiveness to 2,5-dimethoxy-4-iodoamphetamine in liver sinusoidal endothelial cells.  

PubMed

Age-related pseudocapillarization of the liver sinusoidal endothelium is associated with impaired lipid and drug metabolism and the development of disease. 2,5-Dimethoxy-4-iodoamphetamine is a serotonin receptor 2 agonist that has been shown to have beneficial effects on the liver sinusoidal endothelium in the setting of partial hepatectomy. Here, we have assessed whether 2,5-dimethoxy-4-iodoamphetamine influences ultrastructure of the sinusoidal endothelium in normal 7- and 24-month-old C57Bl6 mice. Following 48 hours of 2,5-dimethoxy-4-iodoamphetamine administration, we found that the liver endothelium in the young, but not in the old, mice had increased porosity compared with controls. This effect appeared to be modulated by increased fenestration size rather than a change in fenestration number. 2,5-Dimethoxy-4-iodoamphetamine is a useful manipulator of fenestration size in the young liver and could be harnessed in the search for therapeutic interventions for pseudocapillarization. PMID:23974079

Cogger, Victoria C; Mitchell, Sarah J; Warren, Alessandra; de Cabo, Rafael; Le Couteur, David G

2014-05-01

454

A programmable voltage reference optimized for power management applications  

Microsoft Academic Search

A 3-bits programmable, low drift, high PSRR and high precision voltage reference, optimized for Power Management (PM) applications,\\u000a is presented. The topology is based on a high-performance bandgap voltage reference that presents a PSRR of up to 80 dB, which\\u000a is required in PM applications, because they employ mixed-signal circuits, where high frequency switching noise is present.\\u000a The proposed approach was

Filipe Guimarães Russo Ramos; Luís Henrique Carvalho Ferreira; Tales Cleber Pimenta

2008-01-01

455

Intra-task scenario-aware voltage scheduling  

Microsoft Academic Search

Modern embedded applications usually have real-time constraints and they have requirements for low energy consumption. At system level, intra-task dynamic voltage scaling (DVS) is one of the most effective techniques for energy reduction. It changes the processor's supply voltage and clock frequency to the lowest level that still allows the real-time constraints to be met. In this paper, we present

Stefan Valentin Gheorghita; Twan Basten; Henk Corporaal

2005-01-01

456

MULTIFUNCTIONAL CAPABILITY OF A HIGH-VOLTAGE AC POWER CONDITIONER  

Microsoft Academic Search

Recent implementations of direct connected high-voltage ac power conditioners have focused on fundamental frequency power control, while other control objectives have not been exercised. This paper illustrates the multi-functional capability of a prototype high-voltage (11kV) conditioner and discusses the practicalities of building such a unit. Initial laboratory testing confirms that the unit can perform all four of the proposed functions,

Roger Brough; Shayne Crimp; Alister Gardiner

457

Fos Expression in Neurons of the Rat Vestibulo-Autonomic Pathway Activated by Sinusoidal Galvanic Vestibular Stimulation  

PubMed Central

The vestibular system sends projections to brainstem autonomic nuclei that modulate heart rate and blood pressure in response to changes in head and body position with regard to gravity. Consistent with this, binaural sinusoidally modulated galvanic vestibular stimulation (sGVS) in humans causes vasoconstriction in the legs, while low frequency (0.02–0.04?Hz) sGVS causes a rapid drop in heart rate and blood pressure in anesthetized rats. We have hypothesized that these responses occur through activation of vestibulo-sympathetic pathways. In the present study, c-Fos protein expression was examined in neurons of the vestibular nuclei and rostral ventrolateral medullary region (RVLM) that were activated by low frequency sGVS. We found c-Fos-labeled neurons in the spinal, medial, and superior vestibular nuclei (SpVN, MVN, and SVN, respectively) and the parasolitary nucleus. The highest density of c-Fos-positive vestibular nuclear neurons was observed in MVN, where immunolabeled cells were present throughout the rostro-caudal extent of the nucleus. c-Fos expression was concentrated in the parvocellular region and largely absent from magnocellular MVN. c-Fos-labeled cells were scattered throughout caudal SpVN, and the immunostained neurons in SVN were restricted to a discrete wedge-shaped area immediately lateral to the IVth ventricle. Immunofluorescence localization of c-Fos and glutamate revealed that approximately one third of the c-Fos-labeled vestibular neurons showed intense glutamate-like immunofluorescence, far in excess of the stain reflecting the metabolic pool of cytoplasmic glutamate. In the RVLM, which receives a direct projection from the vestibular nuclei and sends efferents to preganglionic sympathetic neurons in the spinal cord, we observed an approximately threefold increase in c-Fos labeling in the sGVS-activated rats. We conclude that localization of c-Fos protein following sGVS is a reliable marker for sGVS-activated neurons of the vestibulo-sympathetic pathway. PMID:22403566

Holstein, Gay R.; Friedrich Jr., Victor L.; Martinelli, Giorgio P.; Ogorodnikov, Dmitri; Yakushin, Sergei B.; Cohen, Bernard

2012-01-01

458

Charge-pump voltage converter  

DOEpatents

A charge-pump voltage converter for converting a low voltage provided by a low-voltage source to a higher voltage. Charge is inductively generated on a transfer rotor electrode during its transit past an inductor stator electrode and subsequently transferred by the rotating rotor to a collector stator electrode for storage or use. Repetition of the charge transfer process leads to a build-up of voltage on a charge-receiving device. Connection of multiple charge-pump voltage converters in series can generate higher voltages, and connection of multiple charge-pump voltage converters in parallel can generate higher currents. Microelectromechanical (MEMS) embodiments of this invention provide a small and compact high-voltage (several hundred V) voltage source starting with a few-V initial voltage source. The microscale size of many embodiments of this invention make it ideally suited for MEMS- and other micro-applications where integration of the voltage or charge source in a small package is highly desirable.

Brainard, John P. (Albuquerque, NM); Christenson, Todd R. (Albuquerque, NM)

2009-11-03

459

Voltage regulation and battery condition  

Microsoft Academic Search

Charging of automotive lead--acid batteries and the related aspects of voltage regulators are reviewed. Operation and proper setting of voltage regulators for different conditions are discussed. Factors affecting battery counter voltage (cemf) are examined: these include purity of battery materials, state of charge, strength of electrolyte, gassing, maintenance, and temperature--the latter is considered at some length. (RWR)

Wesley

1977-01-01

460

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

E-print Network

of these currents via a voltage source inverter. Simulation and experimental results from a laboratory prototype and the stator teeth even if there is no current in the stator. Another source of torque pulsation results from

461

W-band synthesized signal generator using fundamental voltage controlled oscillators  

Microsoft Academic Search

The architecture and implementation of a W-Band signal generator are described. The architecture presented highlights the developmental areas of: the signal source, frequency control, output control and modulation. Voltage controlled oscillators (VCOs) were developed to provide frequency agility, to enhance the viability of frequency modulation (FM) characteristics, and to improve weight and power management requirements. Frequency control and phase coherence

Joseph A. Molnar; R. Zhorofsky

1997-01-01

462

High voltage dc--dc converter with dynamic voltage regulation and decoupling during load-generated arcs  

DOEpatents

A high-power power supply produces a controllable, constant high voltage output under varying and arcing loads. The power supply includes a voltage regulator, an inductor, an inverter for producing a high frequency square wave current of alternating polarity, an improved inverter voltage clamping circuit, a step up transformer, an output rectifier for producing a dc voltage at the output of each module, and a current sensor for sensing output current. The power supply also provides dynamic response to varying loads by controlling the voltage regulator duty cycle and circuitry is provided for sensing incipient arc currents at the output of the power supply to simultaneously decouple the power supply circuitry from the arcing load. The power supply includes a plurality of discrete switching type dc--dc converter modules. 5 Figs.

Shimer, D.W.; Lange, A.C.

1995-05-23

463

High voltage dc-dc converter with dynamic voltage regulation and decoupling during load-generated arcs  

DOEpatents

A high-power power supply produces a controllable, constant high voltage output under varying and arcing loads. The power supply includes a voltage regulator, an inductor, an inverter for producing a high frequency square wave current of alternating polarity, an improved inverter voltage clamping circuit, a step up transformer, an output rectifier for producing a dc voltage at the output of each module, and a current sensor for sensing output current. The power supply also provides dynamic response to varying loads by controlling the voltage regulator duty cycle and circuitry is provided for sensing incipient arc currents at the output of the power supply to simultaneously decouple the power supply circuitry from the arcing load. The power supply includes a plurality of discrete switching type dc--dc converter modules.

Shimer, Daniel W. (Danville, CA); Lange, Arnold C. (Livermore, CA)

1995-01-01

464

Dynamics of fractional-order sinusoidally forced simplified Lorenz system and its synchronization  

NASA Astrophysics Data System (ADS)

In this paper, dynamical behaviors of the fractional-order sinusoidally forced simplified Lorenz are investigated by employing the time-domain solution algorithm of fractional-order calculus. The system parameters and the fractional derivative orders q are treated as bifurcation parameters. The range of the bifurcation parameters in which the system generates chaos is determined by bifurcation, phase portrait, and Poincaré section, and different bifurcation motions are visualized by virtue of a systematic numerical analysis. We find that the lowest order of this system to yield chaos is 3.903. Based on fractional-order stability theory, synchronization is achieved by using nonlinear feedback control method. Simulation results show the scheme is effective and a chaotic secure communication scheme is present based on this synchronization.

Wang, Yan; Sun, Kehui; He, Shaobo; Wang, Huihai

2014-06-01

465

Fiber-optic project-fringe interferometry with sinusoidal phase modulating system  

NASA Astrophysics Data System (ADS)

A fiber-optic sinusoidal phase-modulating (SPM) interferometer for fringe projection is presented. The system is based on the SPM technique and makes use of the Mach-Zehnder interferometer structure and Young's double pinhole interference principle to achieve interference fringe projection. A Michelson interferometer, which contains the detection of Fresnel reflection on its fiber end face and interference at one input port of a 3 dB coupler, is utilized to achieve feedback precise control of the fringe phase, which is sensitive to phase drifting produced by the nature of the fiber. The phase diversity for the closed-loop SPM system can be real-time measured with a precision of 3 mrad. External disturbances mainly caused by temperature fluctuations can be reduced to 57 mrad for the fringe map. The experimental results have shown the usefulness of the system.

Zhang, Fukai; Duan, Fajie; Lv, Changrong; Duan, Xiaojie; Bo, En; Feng, Fan

2013-06-01

466

El Perfil Sinusoidal del Jet HH 31 en la Protoestrella IRAS 042482612  

NASA Astrophysics Data System (ADS)

In this contribution we study the HH 31 jet; associated with the Class I proto-star; IRAS 042482612 (age 10 yrs); in the Taurus molecular cloud. We use mid-infrared images; taken by Spitzer and WISE; to analyze the sinusoidal or S-shape chain of knots (or EGOs) that delineate the jet. The binarity of the central source naturally explains the wiggling jet. The orbital period is 2.7 times the estimated dynamical time of the jet. The spatial difference between knots agrees with time elapse expected between quasi-periodic FU Orionis events; suggesting that central star might have experimented this type of events several times since its birth. FULL TEXT IN SPANISH

Ferrero, L. V.; Gómez, M. N.

467

P-selectin expression in a colon tumor model exposed by sinusoidal electromagnetic fields  

PubMed Central

P-selectin is mainly involved in the initial process of tumor cell adhesion to platelets. The aim of the present study was to determine the expression level of P-selectin in a colon tumor model affected by sinusoidal electromagnetic fields (SMF). Male Wistar albino rats aged 2-2.5 months were used. The animals were divided into the I [N-Methyl-N-Nitrosurea (MNU)], II (SMF-MNU), III (SMF) and IV (control) groups. The rats were housed five per polycarbonate cage. Sixty milligrams of MNU was dissolved in 6 ml sterile 0.9% NaCl. Prepared solutions were administered intra rectally (i.r.) to the 1st and 3rd groups as 0.2 ml/per animal. The same procedure was applied to the 2nd and 4th groups, although 0.2 ml/per animal sterile isotonic solution was administered instead. This procedure was repeated once a week for 10 weeks. Following the administration of MNU, the 2nd and 3rd groups were exposed to a sinusoidal magnetic field (SMF, 50 Hz, 5 mT) for 6 h/day for 8 months. P-selectin expression of the four groups of rat colon tissues was determined using immunohistochemistry on paraffin sections. The labeled streptavidin biotin method was performed. Fisher’s exact test was used for differences between proportions. Results showed that there was no statistically significant (P>0.05) change in the expression level of P-selectin. However, this result should be verified by both in vivo and in vitro experiments to determine the effects of the magnetic fields on P-selectin. PMID:24648955

TUNCEL, HANDAN; SHIMAMOTO, FUMIO; ÇIRAKO?LU, AY?E; KORPINAR, MEHMET ALI; KALKAN, TUNAYA

2013-01-01

468

Flow pattern and pressure drop of vertical upward gas-liquid flow in sinusoidal wavy channels  

SciTech Connect

Flow patterns and pressure drop of upward liquid single-phase flow and air-water two-phase flow in sinusoidal wavy channels are experimentally studied. The test section is formed by a sinusoidal wavy wall of 1.00 m length with a wave length of 67.20mm, an amplitude of 5.76mm. Different phase shifts between the side walls of the wavy channel of 0{sup o}, 90{sup o} and 180{sup o} are investigated. The flow phenomena, which are bubbly flow, slug flow, churn flow, and dispersed bubbly flow are observed and recorded by high-speed camera. When the phase shifts are increased, the onset of the transition from the bubbly flow to the churn flow shifts to a higher value of superficial air velocity, and the regions of the slug flow and the churn flow are smaller. In other words, the regions of the bubbly flow and the dispersed bubbly flow are larger as the phase shift increases. The slug flow pattern is only found in the test sections with phase shifts of 0{sup o} and 90{sup o}. Recirculating gas bubbles are always found in the troughs of the corrugations. The recirculating is higher when the phase shifts are larger. The relationship between the two-phase multipliers calculated from the measured pressure drops, and the Martinelli parameter is compared with the Lockhart-Martinelli correlation. The correlation in the case of turbulent-turbulent condition is shown to fit the data very well for the phase shift of 0{sup o} but shows greater deviation when the phase shifts are higher. (author)

Nilpueng, Kitti [Department of Mechanical Engineering, South East Asia University, Bangkok 10160 (Thailand); Wongwises, Somchai [Fluid Mechanics, Thermal Engineering and Multiphase Flow Research Lab (FUTURE), Department of Mechanical Engineering, King Mongkut's University of Technology Thonburi, Bangmod, Bangkok 10140 (Thailand)

2006-06-15

469

Stray voltage and milk quality: a review.  

PubMed

If animal contact voltage reaches sufficient levels, animals coming into contact with grounded devices may receive a mild electric shock that can cause a behavioral response. At voltage levels that are just perceptible to the animal, behaviors indicative of perception (eg, flinches) may result with little change in normal routines. At higher exposure levels, avoidance behaviors may result. The direct effect of animal contact with electrical current can range from: • Mild behavioral reactions indicative of sensation, to • Involuntary muscle contraction, or twitching, to • Intense behavioral responses indicative of pain. The indirect effects of these behaviors can vary considerably depending on the specifics of the contact location, level of current flow, body pathway, frequency of occurrence, and many other factors related to the daily activities of animals. There are several common situations of concern in animal environments: • Animals avoiding certain exposure locations, which may result in: X Reduced water intake if exposure is required for animals to access watering devices, X Reduced feed intake if exposure is required for animals to accesses feeding devices or locations. • Difficulty of moving or handling animals in areas of voltage/current exposure• The physiologic implications of the release of stress hormones produced by contact with painful stimuli. The severity of response will depend on the amount of electrical current (measured in milliamps) flowing through the animal’s body, the pathway it takes through the body, and the sensitivity of the individual animal. The results of the combined current dose-response experiments, voltage exposure response experiments, and measurements of body and contact resistances is consistent with the lowest (worst case) cow + contact resistance as low as 500 as estimated by Lefcourt that may occur in some unusual situations on farms (firm application of the muzzle to a wet metallic watering device and hoof contact on a clean, wet, contoured metallic plate on the floor). These studies on responses of dairy cows to electrical exposure agree well with each other and with predictions from neuroelectric theory and practice. There is a high degree of repeatability across studies in which exposures and responses have been appropriately quantified. For confirmation, a potential of 2 to 4 V (60 Hz, rms) must be measured between 2 points that an animal might contact (or animal contact measurement), and some animals should exhibit signs of avoidance behavior. The animal contact voltage measurement with an appropriate shunt resistor value provides the only reliable indication of exposure levels. Voltage readings at cow contact points should be made with a 500- or 1000- resistor across the 2 measuring leads to the cow contact points in addition to open circuit measurements. The only studies that have documented adverse effects of voltage and current on cows had both sufficient current applied to cause aversion and forced exposures (ie, animals could not eat or drink without being exposed to voltage and current) and all of the indirect responses (reduced water or intake and milk production) were behaviorally mediated. It is typical for voltage levels to vary considerably at different locations on a farm. Decreased water and/or feed intake or undesired behaviors result only if current levels are sufficient to produce aversion at locations that are critical to daily animal activity, such as feeders, waterers, and milking areas. If an aversive current occurs only a few times per day, it is not likely to have an adverse effect on cow behavior. The more often an aversive voltage occurs in areas critical to cows’ normal feeding, drinking, or resting, the more likely it is to affect cows. A number of studies have been done to investigate potential detrimental physiologic responses that may result from animals’ exposure to voltage and current. The literature review presented here summarizes 46 research trials on groups of cows exposed to know levels of voltage and/or current. Many o

Reinemann, Douglas J

2012-07-01

470

Influence of the plasma on ICRF antenna voltage limits  

NASA Astrophysics Data System (ADS)

An ion cyclotron range of frequencies (ICRF) probe [F.W. Baity, G.C. Barber, V. Bobkov, R.H. Goulding, J.-M. Noterdaeme, D.W. Swain, in: 14th Topical Conference on Radiofrequency Power in Plasmas, Oxnard 2001, AIP Conference Proceedings 595, AIP, Melville, NY, 2001, p. 510] has been implemented to study voltage stand-off of the ICRF antennas on ASDEX Upgrade (AUG). The probe was operated at first in a test stand where features of high RF voltage operation in vacuum and plasma created by an ion source of the Hall type [Plasma Sources Sci. Technol. 8 (1999) R1] were studied. Vacuum arcs as well as ignition of high voltage glow discharge are candidate processes to explain voltage limits of the ICRF antennas. The setup on AUG was used to expose high RF voltages in real conditions of the tokamak scrape-off layer which are faced by the ICRF antennas. It is found that high voltage breakdown on the ICRF antenna is often correlated with ELM activity. The maximal RF voltage increased from shot to shot, i.e. the conditioning effect is observed. For the good-conditioned ICRF probe it was shown experimentally that the voltage limit can be increased while the rectified current is suppressed at the same time.

Bobkov, V.; Noterdaeme, J.-M.; Wesner, F.; Wilhelm, R.; ASDEX Upgrade Team

2003-03-01

471

Threshold voltage extraction circuit  

E-print Network

NMOS transistor obtained via simulation. 27 Simulation P MOS 9. 6/2. 4 9 I I I I B to X 6g C 0 III ) "b 0 -'LfaS NI) Fig. 17. Graph of 4o and 8(V)n)/8(Vcs) versus Vcs of a PMOS transistor obtained via simulation. SIMULATION RESULTS...ltm/2. 4ltm). 33 Temperature ('C) E Cl Qt nt O 'D O ta I -820 -880 Postlayout Simulation TOt S Fig. 21. Temperature dependence of threshold-voltage of a PMOS transistor ( W/I ? 9. 6ltm/2. 4ltm). In the following subsection, chip...

Hoon, Siew Kuok

2000-01-01

472

Voltage-induced ferromagnetic resonance in magnetic tunnel junctions.  

PubMed

We demonstrate excitation of ferromagnetic resonance in CoFeB/MgO/CoFeB magnetic tunnel junctions (MTJs) by the combined action of voltage-controlled magnetic anisotropy (VCMA) and spin transfer torque (ST). Our measurements reveal that GHz-frequency VCMA torque and ST in low-resistance MTJs have similar magnitudes, and thus that both torques are equally important for understanding high-frequency voltage-driven magnetization dynamics in MTJs. As an example, we show that VCMA can increase the sensitivity of an MTJ-based microwave signal detector to the sensitivity level of semiconductor Schottky diodes. PMID:23003081

Zhu, Jian; Katine, J A; Rowlands, Graham E; Chen, Yu-Jin; Duan, Zheng; Alzate, Juan G; Upadhyaya, Pramey; Langer, Juergen; Amiri, Pedram Khalili; Wang, Kang L; Krivorotov, Ilya N

2012-05-11

473

Voltage-Induced Ferromagnetic Resonance in Magnetic Tunnel Junctions  

NASA Astrophysics Data System (ADS)

We demonstrate excitation of ferromagnetic resonance in CoFeB/MgO/CoFeB magnetic tunnel junctions (MTJs) by the combined action of voltage-controlled magnetic anisotropy (VCMA) and spin transfer torque (ST). Our measurements reveal that GHz-frequency VCMA torque and ST in low-resistance MTJs have similar magnitudes, and thus that both torques are equally important for understanding high-frequency voltage-driven magnetization dynamics in MTJs. As an example, we show that VCMA can increase the sensitivity of an MTJ-based microwave signal detector to the sensitivity level of semiconductor Schottky diodes.

Zhu, Jian; Katine, J. A.; Rowlands, Graham E.; Chen, Yu-Jin; Duan, Zheng; Alzate, Juan G.; Upadhyaya, Pramey; Langer, Juergen; Amiri, Pedram Khalili; Wang, Kang L.; Krivorotov, Ilya N.

2012-05-01

474

Voltage-Induced Ferromagnetic Resonance in Magnetic Tunnel Junctions  

NASA Astrophysics Data System (ADS)

We demonstrate excitation of ferromagnetic resonance in CoFeB/MgO/CoFeB magnetic tunnel junctions (MTJs) by the combined action of voltage-controlled magnetic anisotropy (VCMA) and spin transfer torque (ST). Our measurements reveal that GHz-frequency VCMA torque and ST in low-resistance MTJs have similar magnitudes, and thus that both torques are equally important for understanding high-frequency voltage-driven magnetization dynamics in MTJs. As an example, we show that VCMA can increase the sensitivity of an MTJ-based microwave signal detector to the sensitivity level of semiconductor Schottky diodes.

Zhu, Jian; Katine, Jordan; Rowlands, Graham; Chen, Yu-Jin; Duan, Zheng; Alzate, Juan; Upadhyaya, Pramey; Langer, Juergen; Khalili Amiri, Pedram; Wang, Kang; Krivorotov, Ilya

2012-02-01