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1

Low frequency sinusoidal pressure generator  

NASA Technical Reports Server (NTRS)

Low frequency pressure generator is built to provide sinusoidal driving function in frequency range from 0.05 to 50 Hz for frequency response testing of pressure transducers used in liquid-filled systems. Generator consists of piston-in-cylinder, scotch-yoke mechanism machined into piston, and adjustable eccentric.

Curreri, J. S.

1972-01-01

2

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

SciTech Connect

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

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

2008-08-15

3

LLC series resonant high-frequency sinusoidal power supplier  

Microsoft Academic Search

This paper presents an LLC series resonant high-frequency sinusoidal power supplier for contactless power transmission system utilizing the magnetizing inductance and the leakage inductance of contactless coupled transformer. The design of system's parameters is under 2mm air gap of contactless coupled transformer and utilizes microchip dsPIC30F4011 to track resonance tank voltage and current phase in order to maintain operation of

Liang-Rui Chen; Chung-Ming Young; Hai-Wen Chang; Wen-Ren Yang; Neng-Yi Chu

2010-01-01

4

Sinusoidal voltage controller for uninterruptible power supply by robust control  

Microsoft Academic Search

The output voltage of an uninterruptible power supply (UPS) is distorted by nonlinear loads. To obtain sinusoidal output voltage of a UPS, a new control method of a pulse width modulated (PWM) inverter is proposed applying sliding mode control. The feedback gains of conventional sliding mode control are determined by offline calculation; however this proposed control method calculates the feedback

Tomonobu Senjyu; Katsumi Uezato

1993-01-01

5

A series-parallel compensated uninterruptible power supply with sinusoidal input current and sinusoidal output voltage  

Microsoft Academic Search

In this paper a series-parallel compensated UPS is suggested, which has high input power factor and sinusoidal output voltage regulation capability. Compared to conventional cascaded UPS, the size can be reduced significantly with high quality input and output waveforms. In this paper, analysis and experimental results for a prototype are presented

Seong-Jeub Jeon; Gyu-Hyeong Cho

1997-01-01

6

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

7

Soft-Switched Voltage-Doubler Sinusoidal Rectifier with Balanced Output Capacitor Voltages  

NASA Astrophysics Data System (ADS)

A novel single-phase soft-switched voltage-doubler rectifier is presented. The resonant switch cell for this has a full-bridge DC-DC converter structure built of voltage-bidirectional two-quadrant switch and has a vital function to balance the output capacitor voltages. The switching transitions are mainly governed by a series resonance. The experimental prototype employing four insulated-gate bipolar transistors is implemented to investigate the pulse-width modulated operation. The experimental results confirm that the input current can be waveshaped sinusoidally with a near-unity power factor under the output voltage duplication.

Itoh, Ryozo; Ishizaka, Kouichi

8

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

9

High frequency breakdown voltage  

SciTech Connect

This report contains information about the effect of frequency on the breakdown voltage of an air gap at standard pressure and temperature, 76 mm Hg and O{degrees}C, respectively. The frequencies of interest are 47 MHz and 60 MHz. Additionally, the breakdown in vacuum is briefly considered. The breakdown mechanism is explained on the basis of collision and ionization. The presence of the positive ions produced by ionization enhances the field in the gap, and thus determines the breakdown. When a low-frequency voltage is applied across the gap, the breakdown mechanism is the same as that caused by the DC or static voltage. However, when the frequency exceeds the first critical value f{sub c}, the positive ions are trapped in the gap, increasing the field considerably. This makes the breakdown occur earlier; in other words, the breakdown voltage is lowered. As the frequency increases two decades or more, the second critical frequency, f{sub ce}, is reached. This time the electrons start being trapped in the gap. Those electrons that travel multiple times across the gap before reaching the positive electrode result in an enormous number of electrons and positive ions being present in the gap. The result is a further decrease of the breakdown voltage. However, increasing the frequency does not decrease the breakdown voltage correspondingly. In fact, the associated breakdown field intensity is almost constant (about 29 kV/cm).The reason is that the recombination rate increases and counterbalances the production rate, thus reducing the effect of the positive ions` concentration in the gap. The theory of collision and ionization does not apply to the breakdown in vacuum. It seems that the breakdown in vacuum is primarily determined by the irregularities on the surfaces of the electrodes. Therefore, the effect of frequency on the breakdown, if any, is of secondary importance.

Chu, Thanh Duy

1992-03-01

10

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

11

Advanced Energy Conversion System Using Sinusoidal Voltage Tracking Buck-Boost Converter Cascaded Polarity Changing Inverter  

NASA Astrophysics Data System (ADS)

This paper presents an advanced power converter employs a sinusoidal voltage absolute value tracking buck-boost DC-DC converter in the first power processing stage and a polarity changing full-bridge inverter in the second stage. The proposed power conversion system has the capability of delivering sinusoidal output and input current with unity power factor and good output voltage regulation. Consequently, the complete voltage regulator system, which is mainly suitable for new energy generation systems as well as energy storage systems, can be constructed compactly and inexpensively without DC link electrolytic capacitor. Also, the paper presents an auxiliary passive resonant circuit for soft switching operation. Simulation results using PSIM software are presented to verify the operation principles and feasibility of the proposed power conversion system.

Ahmed, Nabil A.

2011-06-01

12

A three-phase series-parallel compensated line-interactive UPS system with sinusoidal input current and sinusoidal output voltage  

Microsoft Academic Search

This paper deals with a three-phase line-interactive uninterruptible power supply system with active series-parallel power-line conditioning capability, which has sinusoidal output voltage regulation capability and unity power factor. In this system, two active power filter topologies are applied. The first one is a series active power filter which can compensate supply voltage harmonics and voltage unbalances as well. The other

S. A. O. Da Silva; Pedro F. Donoso-Garcia; Porfirio C. Cortizo

1999-01-01

13

Comparison of atmospheric air plasmas excited by high-voltage nanosecond pulsed discharge and sinusoidal alternating current discharge  

NASA Astrophysics Data System (ADS)

In this paper, atmospheric pressure air discharge plasma in quartz tube is excited by 15 ns high-voltage nanosecond pulsed discharge (HVNPD) and sinusoidal alternating current discharge (SACD), respectively, and a comparison study of these two kinds of discharges is made through visual imaging, electrical characterization, optical detection of active species, and plasma gas temperature. The peak voltage of the power supplies is kept at 16 kV while the pulse repetition rate of nanosecond pulse power supply is 100 Hz, and the frequency of sinusoidal power supply is 10 kHz. Results show that the HVNPD is uniform while the SACD presents filamentary mode. For exciting the same cycles of discharge, the average energy consumption in HVNPD is about 1/13 of the SACD. However, the chemical active species generated by the HVNPD is about 2-9 times than that excited by the SACD. Meanwhile, the rotational and vibrational temperatures have been obtained via fitting the simulated spectrum of N2 (C3?u ? B3?g, 0-2) with the measured one, and the results show that the plasma gas temperature in the HVNPD remains close to room temperature whereas the plasma gas temperature in the SACD is about 200 K higher than that in HVNPD in the initial phase and continually increases as discharge exposure time goes on.

Zhang, Shuai; Wang, Wen-chun; Jiang, Peng-chao; Yang, De-zheng; Jia, Li; Wang, Sen

2013-10-01

14

Simulation of high-frequency sinusoidal electrical block of mammalian myelinated axons  

Microsoft Academic Search

High frequency alternating current (HFAC) sinusoidal waveforms can block conduction in mammalian peripheral nerves. A mammalian\\u000a axon model was used to simulate the response of nerves to HFAC conduction block. Sinusoidal waveforms from 1  to 40 kHz were\\u000a delivered to eight simulated axon diameters ranging from 7.3  to 16 ?m. Conduction block was obtained between 3  to 40 kHz.\\u000a The minimum peak to

Niloy Bhadra; Emily A. Lahowetz; Stephen T. Foldes; Kevin L. Kilgore

2007-01-01

15

Sinusoidal voltage control of a single phase uninterruptible power supply by a high gain PI circuit  

Microsoft Academic Search

This paper presents analysis and design of a new control method of a single-phase voltage-source uninterruptible power supply (UPS) inverter with a high Q L-C low-pass filter. When a PWM inverter is used to feed the load, a L-C low-pass filter must be employed to eliminate the switching frequency component of output voltage harmonics. But, it may be observed that

Akira Moriyama; I. Ando; I. Takahashi

1998-01-01

16

Voltage regulation using dynamic voltage restorer for large frequency variations  

Microsoft Academic Search

The paper discusses the voltage regulation of a critical load bus using a dynamic voltage restorer (DVR) in a distribution system. The critical load cannot tolerate any power quality (PQ) disturbance including large frequency variations occurring in the system. The DVR is operated such that it holds the voltage across the critical load bus terminals constant at system nominal frequency

Amit Kumar Jindal; Arindam Ghosh; Avinash Joshi

2005-01-01

17

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. Modelling 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 anaesthetized 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 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 could therefore be a useful alternative to permanent tissue transection in some experimental paradigms. It could also 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

2014-12-01

18

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

19

Algebraic real-time algorithm for B-Spline sinusoidal pulse width modulation in three phase voltage source inverters  

Microsoft Academic Search

In this paper a novel algebraic real-time algorithm for implementation of sinusoidal pulse width modulation (SPWM) based on B-spline carriers is introduced and discussed. B-spline functions are used as carrier signals with the aim to to reduce harmonic content of the three phase inverter output voltage. This algorithm eliminates the problem of B-spline recursive evaluation with convolution integrals or convolution

F. Genduso; R. Miceli; C. Rando

2008-01-01

20

Subspace-based frequency estimation of sinusoidal signals in alpha-stable noise  

Microsoft Academic Search

In the frequency estimation of sinusoidal signals observed in impulsive noise environments, techniques based on Gaussian noise assumption are unsuccessful. One possible way to 6nd better estimates is to model the noise as an alpha-stable process and to use the fractional lower order statistics (FLOS) of the data to estimate the signal parameters. In this work, we propose a FLOS-based

Hakan Deli

21

Subspace-based frequency estimation of sinusoidal signals in alpha-stable noise  

Microsoft Academic Search

In the frequency estimation of sinusoidal signals observed in impulsive noise environments, techniques based on Gaussian noise assumption are unsuccessful. One possible way to 6nd better estimates is to model the noise as an alpha-stable process and to use the fractional lower order statistics (FLOS) of the data to estimate the signal parameters. In this work, we propose a FLOS-based

Mustafa A. Altinkaya; Hakan Deliç; Bülent Sankur; Emin Anarim

2002-01-01

22

Stabilizing optical feedback-induced chaos by sinusoidal modulation beyond the relaxation frequency in semiconductor lasers  

NASA Astrophysics Data System (ADS)

We report on stabilizing the chaotic dynamics of semiconductor lasers under optical feedback (OFB) by means of sinusoidal modulation at frequencies far beyond the relaxation frequency of the laser. The laser is assumed to be coupled to a short external cavity, which is characterized by a resonance frequency spacing higher than the relaxation frequency. The study is based on a time delay rate equation model of OFB, which is suitable for treating the regime of strong OFB and considering multiple reflections in the external cavity. We show that the intensity modulation response of the chaotic laser under strong OFB is enhanced over a narrow frequency band near the doubled relaxation frequency due to a photon-photon resonance. Within this high-frequency band, the sinusoidal modulation may convert the chaotic attractor to a limit cycle, and the small-signal modulation suppresses the relative intensity noise (RIN) to a level only 2 dB higher than the RIN level of the solitary laser.

Bakry, A. H.; Ahmed, M.

2014-10-01

23

Design and performance of a passive EMI filter for use with a voltage-source PWM inverter having sinusoidal output voltage and zero common-mode voltage  

Microsoft Academic Search

This paper deals with integrating a small-sized passive electromagnetic interference (EMI) filter with a voltage-source pulse-width modulated (PWM) inverter. The purpose of the filter is to eliminate both high-frequency common-mode and normal-mode voltages from the three-phase output voltages of the inverter. A laboratory system consisting of a 5-kVA inverter, a 3.7-kW induction motor, and a specially-designed passive EMI filter was

Hirofumi Akagi; Hiroshi Hasegawa; Takafumi Doumoto

2004-01-01

24

The Doppler frequency of reflected radio waves from a travelling ionospheric disturbance in the mode of a sinusoidal surface  

Microsoft Academic Search

In the geometrical optics approximation, the Doppler frequency of radio waves reflected from a traveling ionospheric disturbance (TID) in the mode of a sinusoidal perfectly reflecting surface is determined

O. L. Ivantyshyn; V. V. Koshevoj; O. E. Levitski

1997-01-01

25

A Series Voltage Regulator based on Quasi-Sinusoidal Waveform to Achieve Smart-Grid Requirements  

Microsoft Academic Search

Smart-Grid has emerged as an important requirement to achieve high quality voltage supplied to customers. Within the context of general power quality indicators, a common problem found in distribution systems is the unbalanced voltage. Usually, to solve this type of disturbance, a step voltage regulator can be used to obtain voltage amplitude compensation. However, for many applications, this device does

Igor Amariz Pires; B. de Jesus Cardoso Filho; J. C. de Oliveira

2010-01-01

26

DECOMPOSING SIGNALS INTO A SUM OF AMPLITUDE AND FREQUENCY MODULATED SINUSOIDS USING PROBABILISTIC INFERENCE  

E-print Network

to be decomposed into a sum of amplitude modulated and fre- quency modulated sinusoids (AM-FM sinusoids) [1, 2]. Per- haps the most popular decomposition of this type first filters the signal and then demodulates the subbands, for example using the Hilbert Transform. Despite its popularity, subband demodulation often

Sahani, Maneesh

27

50 MHz Voltage-to-Frequency Converter  

NASA Astrophysics Data System (ADS)

The Voltage-to-Frequency Converter (V2F) is an instrument commonly used in synchrotron beam line experiments for converting a slowly varying voltage signal representing x-ray flux to a high frequency pulse train, with each pulse representing a packet of x-ray energy. The pulses are commonly integrated with a digital counter to calculate total x-ray energy incident on a sample during an exposure. As x-ray experiment data is taken faster and faster and exposure times shrink, V2F frequencies must necessarily increase to preserve precision in measuring total x-ray energy. The APS Detector Group have designed and built two custom 50MHz V2F instruments for APS beam line experiments. The instruments are designed according to the Nuclear Instrument Module (NIM) standard and respectively reside at APS Sector 12-BM, and in the APS Detector Pool [1].

Madden, T.; Baldwin, J.

2014-03-01

28

Phasors and Sinusoids  

NSDL National Science Digital Library

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

Svoboda, James A.

2010-07-12

29

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

30

Electric current flow through human skin at power frequency voltages  

PubMed Central

Carter, A.O., and Morley R. (1969).Brit. J. industr. Med.,26, 217-223. Electric current flow through human skin at power frequency voltages. Alternating power voltages were applied to small pieces of living skin. Current and voltage were recorded continuously using voltages from 25 V to 250 V. At the lower voltages the skin appeared unaffected, but rapid destruction occurred at the higher voltages. It is concluded that skin impedance, whilst being extremely variable on account of many physical factors, is dependent on voltage and time of application in the range where dangerous electric shock occurs to human beings at power frequencies. PMID:5794946

Carter, A. O.; Morley, R.

1969-01-01

31

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

32

Detection of sinusoidal amplitude modulation in logarithmic frequency sweeps across wide regions of the spectrum  

PubMed Central

Many natural sounds such as speech contain concurrent amplitude and frequency modulation (AM and FM), with the FM components often in the form of directional frequency sweeps or glides. Most studies of modulation coding, however, have employed one modulation type in stationary carriers, and in cases where mixed-modulation sounds have been used, the FM component has typically been confined to an extremely narrow range within a critical band. The current study examined the ability to detect AM signals carried by broad logarithmic frequency sweeps using a 2-alternative forced-choice adaptive psychophysical design. AM detection thresholds were measured as a function of signal modulation rate and carrier sweep frequency region. Thresholds for detection of AM in a sweep carrier ranged from -8 dB for an AM rate of 8 Hz to -30 dB at 128 Hz. Compared to thresholds obtained for stationary carriers (pure tones and filtered Gaussian noise), detection of AM carried by frequency sweeps substantially declined at low (12 dB at 8 Hz) but not high modulation rates. Several trends in the data, including sweep- versus stationary-carrier threshold patterns and effects of frequency region were predicted from a modulation filterbank model with an envelope-correlation decision statistic. PMID:20144700

Hsieh, I-Hui; Saberi, Kourosh

2010-01-01

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

Discrimination of sinusoidally frequency-modulated sound signals mimicking species-specific communication calls in the FM-bat Phyllostomus discolor  

Microsoft Academic Search

In the lesser spear-nosed bat, Phyllostomus discolor, maternal directive calls are characterized by an individual type of sinusoidal frequency modulation (=?SFM) pattern. Beside\\u000a modulation frequency, modulation depth, carrier frequency, and number of modulation cycles per call contribute to the mother's\\u000a vocal signature. Since juvenile P. discolor learn to adapt their isolation calls to the corresponding call characteristics of the own

K.-H. Esser; B. Lud

1997-01-01

35

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

36

Double diffusion convection under sinusoidal modulations of low-frequency vibrations  

Microsoft Academic Search

Double diffusion convection features the coupling of diffusion fluxes driven by the temperature and concentration gradients and the simultaneous existence of the natural convection driven by the buoyancy force. This paper studies the double diffusion convection under different modulations of low-frequency g-jitters in order to evaluate the g-jitter effect on diffusion-dominated experiments in space laboratories. The numerical simulation for a

Yu Yan; Antonio Viviani; M. Ziad Saghir

2008-01-01

37

An optimal and flexible control strategy for active filtering and power factor correction under non-sinusoidal line voltages  

Microsoft Academic Search

This paper gives a new insight into the concept of load compensation under distorted voltages. Achieving both unity power factor (UPF) and perfect compensation of current harmonics are not possible where competition will arise between these two important factors. Through evaluating the present control strategies, a generalized, optimal, and flexible control strategy (OFC) for harmonic compensation of utility lines is

S. Mohammad-Reza Rafiei; Hamid A. Toliyat; Reza Ghazi; Tilak Gopalarathnam

2001-01-01

38

Ability of Electric Field Strength, Frequency, and Current Duration to Stun Farmed Atlantic Salmon and Pollock and Relations to Observed Injuries Using Sinusoidal and Square Wave Alternating Current  

Microsoft Academic Search

The effects of electricity as a stunning method in the slaughtering process of Atlantic salmon Salmo salar and pollock Pollachius virens were studied. About 330 slaughter-sized Atlantic salmon were exposed to sinusoidal alternating current (AC) in seawater. Electrical field strength ranged from 25 to 100 V\\/m and current duration from 1 to 10 s at frequencies between 30 and 2,000

Bjorn Roth; Dag Moeller; Erik Slinde

2004-01-01

39

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

E-print Network

role and the importance of the rotor angle stability as a key criterion in power system stability/reactive power balance and subsequently participation in frequency/voltage regulation is assigned to VSWTs [2 energy stored in spinning rotor proportional to grid frequency gradient for primary frequency control

Silva, Filipe Faria Da

40

Theory of a relativistic orotron with a sinusoidal distribution of the high-frequency field along the electron trajectories  

NASA Astrophysics Data System (ADS)

The interaction between a relativistic electron beam and an HF field with a sinusoidal distribution is studied theoretically. It is noted that the results obtained can be used to construct orotrons (diffraction-radiation generators) with a simple electrodynamic system, i.e., homogeneous along the electron trajectories.

Zaitsev, N. I.; Kovalev, N. F.

41

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

Microsoft Academic Search

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

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

2005-01-01

42

Frequency to Voltage Converter as a Phase Controller in Phase Shifting Interference Microscopy  

Microsoft Academic Search

A new system for the control of a piezoelectric device is introduced. It works as a phase shifter in an interference optical microscope. This circuit translates controllable constant frequency signals, generated with a standard sound card, to electrical signals with constant voltage through a frequency-to-voltage converter; this full analog conversion allows for producing voltage steps of 16 µv, which is a

Jesús González-Laprea; José Cappelletto; Rafael Escalona

2011-01-01

43

A multi-level buck converter based rectifier with sinusoidal inputs and unity power factor for medium voltage (4160-7200 V) applications  

Microsoft Academic Search

A novel rectifier topology for high power (0.5 to 10 MVA) current source based AC motor drives is proposed. This rectifier is composed of a multi-winding transformer, a multilevel diode rectifier and a multi-level buck converter. The rectifier produces near unity input power factor and sinusoidal input current under any operating conditions. In addition, the proposed rectifier has a few

M. L. Zhang; B. Wu; Y. Xiao; F. Dewinter; R. Sotudeh

1999-01-01

44

A multilevel buck converter based rectifier with sinusoidal inputs and unity power factor for medium voltage (4160-7200 V) applications  

Microsoft Academic Search

A novel rectifier topology for high power (0.5 to 10 MVA) current source based AC motor drives is proposed. This rectifier is composed of a multi-winding transformer, a multi-level diode rectifier and a modified multi-level buck converter. The rectifier produces near unity input power factor and sinusoidal input current under any operating conditions. In addition, the proposed rectifier features reliable

Michael Lan Zhang; Bin Wu; Yuan Xiao; F. A. Dewinter; R. Sotudeh

2002-01-01

45

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

46

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

47

High-resolution fiber-optic low-frequency voltage sensor based on the electrostrictive effect  

Microsoft Academic Search

A minimum detectable voltage of 40 nV\\/?Hz at 1 Hz is demonstrated in a fiber-optic interferometric low-frequency voltage sensor. The device maintains good resolution below 1 Hz, providing a minimum detectable voltage of 55 nV\\/?Hz at 0.1 Hz and 129 nV\\/?Hz at 0.03 Hz. High resolution at low frequencies is attainable due to the nonlinear strain response of the electrostrictive

L. Fabiny; S. T. Vohra; F. Bucholtz

1993-01-01

48

Estimation of the Frequency of Instantaneous Voltage Drops Dependent on Arrangement of Line Surge Arresters  

NASA Astrophysics Data System (ADS)

Lightning faults on transmission lines often cause instantaneous voltage drops in power systems. Influences of instantaneous voltage drops become increasingly serious in high technology industries etc. As countermeasures of instantaneous voltage drops, uninterruptible power supplies (UPS) are employed. On the other hand, line surge arresters are installed on transmission lines increasingly as one of the effective countermeasures of double-circuit faults caused by lightning strokes. Additionally, the arresters are effective as one of the reduction methods for the frequency of instantaneous voltage drops. In this paper, the frequency of instantaneous voltage drops reduced by installation of line surge arresters on transmission lines is estimated by employing EMTP analysis. Also, the accuracy of the method in estimating the frequency of instantaneous voltage drops in power systems is evaluated through comparison with experience.

Kawamura, Hironao; Kozuka, Masahiro; Itamoto, Naoki; Shinjo, Kazuo; Ishii, Masaru

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

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

Microsoft Academic Search

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

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

1999-01-01

51

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

Microsoft Academic Search

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

Daolian Chen

2008-01-01

52

55.2: Fast Switching Dual-Frequency Liquid Crystal Optical Retarder, Driven by an Amplitude and Frequency Modulated Voltage  

Microsoft Academic Search

We employed amplitude and frequency modulated voltage in fast switching optical retarder with a high pretilt angle dual-frequency nematic cell. We obtained the response times 150 - 500 µs for an optical retardation shift on 0.3 - 2.2 µm in optical retarder with 12 µm thick nematic cell. The results could be used in beam steering, adaptive optics and display

Andrii B. Golovin; Sergij V. Shiyanovskii; Oleg D. Lavrentovich

2006-01-01

53

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

E-print Network

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

Smith, Sterling Lane

1993-01-01

54

46 CFR 111.01-17 - Voltage and frequency variations.  

Code of Federal Regulations, 2012 CFR

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

2012-10-01

55

46 CFR 111.01-17 - Voltage and frequency variations.  

Code of Federal Regulations, 2010 CFR

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

2010-10-01

56

46 CFR 111.01-17 - Voltage and frequency variations.  

Code of Federal Regulations, 2013 CFR

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

2013-10-01

57

46 CFR 111.01-17 - Voltage and frequency variations.  

Code of Federal Regulations, 2011 CFR

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

2011-10-01

58

46 CFR 111.01-17 - Voltage and frequency variations.  

Code of Federal Regulations, 2014 CFR

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

2014-10-01

59

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

Microsoft Academic Search

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

Biswajit Maity; Gaurav Bhagat; Pradip Mandal

2011-01-01

60

Voltage and Frequency Control With Adaptive Reaction Time in Multiple-Clock-Domain Processors  

E-print Network

through cycle-accurate simula- tion over a wide set of MediaBench and SPEC2000 benchmarks. Compared Dynamic Voltage and Frequency Scaling (DVFS) schemes have been proposed in the literature to improve/frequency changes. Specifically, during the time interval, certain system metrics or statistics are monitored

Martonosi, Margaret

61

Using Automatic Frequency Shifting Techniques for LLC-SRC Output Voltage Regulation  

Microsoft Academic Search

In this paper, an automatic frequency shifting technique is developed for achieving output voltage regulation of LLC series resonant converter (LLC-SRC). Furthermore, the operating modes and dc characteristics are discussed for designing the steady state operating point. Finally, an LLC-SRC, rated about 90 W with operating frequency range from 92 KHz to 102 KHz is provided to verify the control

Kuo-Kai Shyu; Ching-Ming Lai; Ko-Wen Jwo; Ming-Ho Pan; Chung-Ping Ku

2006-01-01

62

Bipolarity phase-shifted controlled voltage mode AC\\/AC converters with high frequency AC link  

Microsoft Academic Search

A circuit topology family of the voltage mode AC\\/AC converters with high frequency AC link are proposed. The kind of circuit topologies are constituted of input cycloconverter, high frequency transformer, and output cycloconverter. The bipolarity phase-shifted control strategy and steady principles are deeply investigated. The output characteristics of the converters are given. By using commutation overlap of the output cycloconverter

Daolian Chen; Lei Li

2003-01-01

63

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

64

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

NASA Astrophysics Data System (ADS)

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

Chen, Lili; Zhou, Wu

2013-06-01

65

Theoretical Analyses of Cellular Transmembrane Voltage in Suspensions Induced by High-frequency Fields.  

PubMed

A change of the transmembrane voltage is considered to cause biophysical and biochemical responses in cells. The present study focuses on the cellular transmembrane voltage (??) induced by external fields. We detail analytical equations for the transmembrane voltage induced by external high-frequency (above the relaxation frequency of the cell membrane) fields on cells of a spherical shape in suspensions and layers. At direct current (DC) and low frequencies, the cell membrane was assumed to be non-conductive under physiologic conditions. However, with increasing frequency, the permittivity of the cytoplasm/extracellular medium and conductivity of the membrane must be accounted for. Our main work is to extend application of the analytical solution of ?? to the high-frequency range. We first introduce the transmembrane voltage generated by DC and low-frequency exposures on a single cell. Then, we focus on cell suspensions exposed to high-frequency fields. Using the effective medium theory and the reasonable assumption, the approximate analytical solution of ?? on cells in suspensions and layers can be derived. Phenomenological effective medium theory equations cannot be used to calculate the local electric field of cell suspensions, so we raised a possible solution based on the Bergman theory. PMID:25528063

Zou, Yong; Wang, Changzhen; Peng, Ruiyun; Wang, Lifeng; Hu, Xiangjun

2015-04-01

66

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

67

Active-R sinusoidal oscillators using the CFA pole  

Microsoft Academic Search

Three new sinusoidal oscillators using ihe curreni feedback amplifier (CFA) pole are presented. Two of the proposed sinusoidal oscillators consist of CFAs and resistors without external capacitances. Their oscillation condition and frequency can be independently controlled by two resistors. Experimental results were given lo demonstrate the feasibility of the proposed circuits. The proposed circuits will be suitable for high-frequency applications

SHEN-IUAN LIU; CHENG-CHIEH CHANG; DONG-SHIUH WU

1994-01-01

68

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

NASA Astrophysics Data System (ADS)

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; Frankowski, Marek; Wrona, Jerzy; Stobiecki, Tomasz; Ogrodnik, Piotr; Barna?, Józef

2014-08-01

69

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

70

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

Microsoft Academic Search

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

Ion Radu; Ray Bartnikas; Michael R. Wertheimer

2003-01-01

71

A study about partial discharge measurements performed applying to insulating systems square voltages with different rise times  

Microsoft Academic Search

Partial discharge (PD) measurements output, when non-sinusoidal voltages are applied to insulating systems, can have different meanings, depending on the voltage waveform frequency content and on the PD probe circuit. A PD detection circuit is designed for a low noise-to-signal ratio, thus for suppression of the residual high frequency (HF) voltage. Such a suppression varies with the applied voltage rise

F. Guastavino; G. Coletti; A. Ratto; E. Torello

2005-01-01

72

Synthesis of sheath voltage drops in asymmetric radio-frequency discharges  

NASA Astrophysics Data System (ADS)

A sheath voltage drop in asymmetric discharges is one of the most important parameters of radio-frequency capacitively coupled plasmas because it determines the kinetic energy of the ions incident on the target or substrate. In this study, we developed a numerical simulation code to estimate the sheath voltage drops and, consequently, the self-bias voltage. We roughly approximated general asymmetric rf discharges to one-dimensional spherical ones. The results obtained by using our simulation code are consistent with measurements and Lieberman's theory.

Yonemura, Shigeru; Nanbu, Kenichi; Iwata, Naoaki

2004-07-01

73

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

74

Sinusoids: Applications and Modeling  

NSDL National Science Digital Library

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

Roberts, Lila F.; Hill, David R.

2004-07-21

75

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

NASA Astrophysics Data System (ADS)

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

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

2003-03-01

76

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

77

Power-Frequency Voltage Withstand Characteristics of Insulations of Substation Secondary Systems  

Microsoft Academic Search

The insulation of secondary system in substation, including secondary cables and devices, have to endure the high ac power-frequency voltage during the short-circuit fault. The ac withstand characteristics of the secondary cables and devices are experimentally investigated and discussed in this paper. The insulation breakdown mechanism of relays can be classified into three modes: air gap breakdown, creeping discharge, and

Jinliang He; Zhanqing Yu; Rong Zeng; Bo Zhang; Shuiming Chen; Jun Hu

2010-01-01

78

Wave amplification by a relativistic electron beam in a planar electrostatic system with sinusoidal-ripple boundary  

SciTech Connect

Primary study is devoted to the amplification mechanism of electromagnetic fast wave by a relativistic electron beam in a planar electrostatic system, where the superplate of two parallel metallic plates is corrugated with sinusoidal ripples and connected to a negative voltage, while the subplate is smooth and grounded. In the system the electrostatic field governs the electrons to move along approximately sinusoidal trajectories and pumps the kinetic energy of electrons to the wave. Under exclusion of the space-charge wave effect and the Smith-Purcell effect, the fast wave gets relativistic Doppler upshift frequency and gain by extracting energy from a sheet electron beam, which is very similar to that in a free-electron laser pumped by a magnetostatic wiggler. Formulas derived and numerical analysis indicate that the amplification mechanism of wave pumped by the planar electrostatic system with sinusoidal ripples is favorable for a mildly relativistic electron beam to generate terahertz wave.

Zhang Shichang [Institute of Photoelectronics, Campus Mail Box 50, Southwest Jiaotong University, Chengdu SC610031 (China)

2009-09-15

79

Voltage calibration of dual-frequency liquid crystal devices for infrared beam steering applications  

NASA Astrophysics Data System (ADS)

This paper addresses the use of liquid crystal devices for electro-optic infrared laser beam steering, such as liquid crystal optical phased arrays (OPAs) and digital beam deflectors (DBDs). In these devices, voltages are synchronously applied to different liquid crystal pixels to steer light, either by diffraction and/or refraction using birefringent prisms. Dual frequency liquid crystals provide an order of magnitude higher speed as compared to conventional nematic liquid crystals, at the cost of more complex addressing algorithms and control circuits. In order to optimize the optical performance of a liquid crystal device, the control voltages must be calibrated. This procedure involves adjustment of the control voltages while monitoring the optical efficiency, and must be done for both steady-state phase levels as well as transitions between phase levels. Manual voltage calibration is unrealistically time consuming for multi-channel beam steering devices. Computer based calibration algorithms for dual frequency liquid crystal devices are discussed, and results are presented for both steady state and dynamic voltage calibration procedures.

Mahajan, Milind; Wen, Bing; Bhupathy, Vinay; Taber, Donald; Winker, Bruce

2005-08-01

80

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

81

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

82

Modeling and design of a novel voltage control system for three phase fixed frequency static power supplies  

SciTech Connect

Pulse width modulated voltage source inverters (PWM VSI) for uninterruptible power supply (UPS), parallel redundant system applications require fast acting inverter output current and voltage control. This paper describes a multivariable state feedback control technique for the design of the voltage regulator for a three phase current controlled PWM VSI. The control method provides a fast response and robust control (insensitive to plant parameter variations) of the load voltage in the presence of load/line disturbances. The voltage regulator is operated in the rotating d-q frame in synchronism with the fundamental frequency. The state space model of the plant of the voltage regulator is developed in the d-q frame. The description and analysis of the voltage control method is presented. A simple procedure to design the voltage regulator has been outlined and digital simulations are carried out which demonstrate the excellent dynamic performance of the voltage control system.

Tripathi, A.; Dewan, S.B. [Univ. of Toronto, Ontario (Canada). Dept. of Electrical and Computer Engineering

1995-12-31

83

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

84

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

85

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

NASA Astrophysics Data System (ADS)

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

2006-06-01

86

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

87

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

PubMed

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

Dharia, Sameera; Rabbitt, Richard D

2010-01-01

88

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

E-print Network

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

Aguglia, D

2014-01-01

89

Computationally Efficient Steady-State Solution of the Bloch Equations for Rapid Sinusoidal Scans Based on Fourier Expansion in Harmonics of the Scan Frequency  

PubMed Central

Rapid-scan EPR has been shown to improve the signal-to-noise ratio relative to conventional continuous wave spectroscopy. Equations are derived for the steady-state solution to the Bloch equations as a Fourier expansion in the harmonics of the scan frequency. This simulation method is about two orders of magnitude faster than time-domain numerical integration. PMID:24678142

Tseitlin, Mark; Eaton, Gareth R.; Eaton, Sandra S.

2014-01-01

90

Sinusoidal Potential and Cosmology  

NASA Astrophysics Data System (ADS)

The nature of dark matter (and dark energy) remains a mystery. An alternative is being explored by several scientists: changing Einstein's field equations. With the exception of cosmologists, astronomers generally have been content to test the older alternative, MOdified Newtonian Dynamics (Milgrom 1984) that challenges Newton but leaves relativistic gravity as an issue for the future. At recent meetings of the AAS, I have presented evidence for a new, non-Newtonian, potential, the sinusoidal potential, ? = (GM/r) cos(ko r), where 2 ? / ko = 425 pc is a proposed universal constant. Instead of Poisson's equation, this potential satisfies an equation similar to Helmholtz equation, ? 2?m +ko2?m = 4? G ? m. At AAS 200, I showed that a similar equation for electricity, the Proca equation, ? 2?e - ko 2?e = -4? rhoe (with the same ko as for gravity) could remove the need for dark matter to bind the Coma cluster. Conventional electrodynamics can readily be extended to include ko (Goldhaber & Nieto 1971). Recently I have found how to include ko in relativistic gravity. I will show how this inclusion affects the interpretation of the Cosmic Microwave Background and the expansion of the universe.

Bartlett, D. F.

2004-05-01

91

Second generation dc SQUID sensors: ROS with frequency readout and DROS with voltage readout  

SciTech Connect

Relaxation Oscillation SQUIDs (ROSs) based on 4x4 {mu}m{sup 2} Nb/AlO{sub x} Josephson tunnel junctions have been fabricated and characterized. A ROS consists of a hysteretic dc SQUIID shunted by an inductor L and a resistor R in series to induce the relaxation oscillations. The values of L range from 20 nH up to about 300 nH, whereas the time constant L/R are between 8 and 45 ns. Frequency-flux characteristics have been recorded with the help of a spectrum analyzer, directly connected to the ROS. The relaxation frequencies range from 5 to 180 MHz. The experimental characteristics can be explained very well with a simple model describing the oscillation cycle. The effect of the self-induced magnetic field due to a magnetic coupling between the dc SQUID and the shunt circuit has been studied in detail. The sensitivity of ROSs and DROSs (Double Relaxation Oscillation SQUIDs) improves with increasing relaxation frequency. In (D)ROSs based on unshunted, hysteretic tunnel junction dc SQUIDS, the maximum relaxation frequency and the sensitivity are limited by LC resonances due to the SQUID capacitance and the shunt inductance. It is shown that the relaxation frequency can be increased up to frequencies of the order of 1 GHz if an extra resistor is integrated to damp these resonances. The optimum value of the damping resistor can be obtained from the ROS parameters. For stable operation of a (D)ROS, the shunt resistance should not be too large. The optimum value of this resistance can be calculated from the effective McCumber parameter and the bias current. Theoretically, the sensitivity of a ROS with a SQUID capacitance of 1 pF, a SQUID inductance of 20 pH and a relaxation frequency of 1 GHz equals about 5, where h is Planck`s constant. In a DROS with voltage readout based on similar SQUIDS, the theoretical sensitivity at a relaxation frequency of 1 GHz is 17h, with an estimated flux-to-voltage transfer coefficient of 5 mV/{phi}{sub 0}.

Adelerhof, D.J.; Duuren, M. van; Flokstra, J.; Rogalla, H. [Univ. of Twente, Enschede (Netherlands)

1994-12-31

92

The influence of switching phase and frequency of voltage on the vibration damping effect in a piezoelectric actuator  

NASA Astrophysics Data System (ADS)

In a structural system with piezoelectric actuators, a damping effect can be achieved by properly switching the voltage on the actuators. Switched voltage methods based on piezoelectric actuators, including active bang-bang control and semi-active synchronized switch damping methods, have become an important category of vibration damping approach. Since the switching phase and switching frequency are critical factors to damping performance, their influence on converted energy in a piezoelectric actuator is investigated under the condition that the switched voltage is constant. The converted energy with randomly switched voltage is also investigated theoretically and numerically. Finally an example of beam vibration with synchronized switch damping on inductor (SSDI) control and synchronized switch damping on voltage source (SSDV) control is used to illustrate how the switching frequency can affect the control performance of different modes in a multiple-degree-of-freedom system.

Ji, Hongli; Qiu, Jinhao; Xia, Pinqi; Guyomar, Daniel

2011-01-01

93

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

94

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

E-print Network

be mounted in trucks that could be dispatched in an emergency to "rescue" a section of line from icing. A setBreaking the ice: de-icing power transmission lines with high-frequency, high-voltage excitation. High-frequency excitation at approximately 8-200 kHz has been proposed as a method to melt ice [1], [2

95

The application of a medium voltage (4160 VAC) variable frequency drive on an underground mine belt conveyor system  

Microsoft Academic Search

High performance underground mine conveyor belts require special starting and operating characteristics. This paper is a summary of how a medium voltage (4160 VAC) variable frequency drive (VFD) was used to meet these requirements. The belt drive system consists of a mandated primary switch gear, drive rated transformer with controlled inductance, variable frequency drive, output switchgear and operational requirements. Items

V. L. Kitts; W. K. Stees

2000-01-01

96

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

PubMed

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

Lee, Hyung-Min; Ghovanloo, Maysam

2013-06-01

97

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

NASA Astrophysics Data System (ADS)

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.

Scandurra, Graziella; Giusi, Gino; Ciofi, Carmine

2014-04-01

98

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

99

A single phase uninterruptible power supply system using a bidirectional sinusoidal PWM inverter  

Microsoft Academic Search

This paper presents an uninterruptible power supply system using a bidirectional sinusoidal PWM inverter. This system offers a smooth transition during grid failure, load voltage stabilisation under varying input grid voltage and lower line current harmonic distortion. The inverter maintains the load voltage and the power flow from the grid by controlling its magnitude and phase angle with respect to

C. V. Nayar; M. Ashari; W. W. L. Keerthipala

1998-01-01

100

Variable-frequency Pulse-Width-Modulation (PWM) for zero voltage switching in a boost dc-dc regulator  

NASA Astrophysics Data System (ADS)

A technique for operating a pulse width modulated (PWM) dc-dc regulator in the boost mode while switching the MOSFET when the drain-to-source potential is near zero volts was developed and is described. This is accomplished by using frequency-modulation in addition to pulse width modulation. Zero-voltage switching will provide power converter designers an alternative for designing high frequency converters with minimal transient turn-on losses, the predominant form of converter losses experienced in high frequency operation. High frequency operation will result in smaller reactive components, which produce higher power density converters, as well as increasing the transient response of the regulated converter. In addition to allowing for high frequency operation, the design exhibits many desirable power switch properties, such as limiting the peak voltage to the output voltage level and operating with the minimum possible current levels for a given power requirement. A circuit built and tested utilizing zero-voltage switching in a regulated boost converter verified the principles of operation for yielding a high efficiency, high frequency converters.

Hunter, Daniel S.

1990-03-01

101

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

102

Photoacoustic effect in a sinusoidally modulated structure  

NASA Astrophysics Data System (ADS)

We derive solutions to an inhomogeneous Mathieu equation that describes the photoacoustic effect in a one-dimensional phononic structure whose acoustic properties vary sinusoidally in space. Solutions show splitting of resonances, the space equivalent of subharmonic generation, and spatial confinement. Properties of the photoacoustic effect including the damping of waves inside the band gaps, the dispersion relation, the positions and widths of the gaps, the frequencies of resonances, and the space dependence of the acoustic waves can be found in closed form from known properties of Mathieu functions.

Wu, Binbin; Diebold, Gerald J.

2012-04-01

103

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

104

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

Microsoft Academic Search

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

Hossein Sepahvand; Jingsheng Liao; Mehdi Ferdowsi

2011-01-01

105

Design of a H{sub {infinity}}-optimal servo compensator for the frequency and voltage control of power plants  

SciTech Connect

This contribution investigates modern H{sub {infinity}} control concepts for frequency and voltage control of power plants. Based on a linearized model for a national grid H{sub {infinity}}-optimal servo compensators have been designed using a frequency domain approach recently published by the authors. As demonstrated in this paper, the multivariable H{sub {infinity}}-controller shows superior performance with respect to setting time and damping of oscillations compared to classical controllers of P/PID type.

Kiffmeier, U.; Unbehauen, H. [Ruhr-Univ. Bochum (Germany)

1994-12-31

106

The unipolarity phase-shifted controlled voltage mode AC-AC converters with high frequency AC link  

Microsoft Academic Search

A circuit configuration and circuit topological family of voltage mode ac-ac converters with high frequency ac links, which are based on forward converters, and a uni-polarity phase-shifted control strategy are proposed and deeply investigated. These kinds of converters consist of a input cycloconverter, a high frequency transformer, an output cycloconverter, input and output filters, and can transfer an unsteady ac

Daolian Chen; Jian Liu

2006-01-01

107

The unipolarity phase-shifted controlled voltage mode AC\\/AC converters with high frequency AC link  

Microsoft Academic Search

The uni-polarity phase-shifted controlled voltage mode AC\\/AC converters with high frequency ac link are firstly proposed and deeply investigated. The converters are constituted of input cycloconverter, high frequency transformer, output cycloconverter, input and output filters. It includes full bridge-full wave mode and full bridge-full bridge mode topologies. By using phase shifting control, the leakage inductance energy and the output filtering

Lei Li; Daolian Chen; Haitao Zhang; Hailang Pan

2003-01-01

108

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

109

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

110

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

111

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

112

Aging of magnetic wire in the presence of variable frequency, high rise time and high voltage pulses  

Microsoft Academic Search

A novel method for the aging of magnetic wire in the conditions that resemble the stresses to insulation caused by power inverters is described. The test system for the purposes of the described aging program is discussed. A model of aging of magnet wire is developed and confirmed with experimental results. It has been found that voltage, temperature and frequency

V. Divljakovic; J. Kline; D. Barta; D. Floryan

1994-01-01

113

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

SciTech Connect

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

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

2009-11-15

114

High frequency deadbeat control of three phase PWM inverter used for uninterruptible power supply  

Microsoft Academic Search

A digital control technique is proposed to obtain a sinusoidal three-phase pulsewidth-modulated (PWM) inverter output. By sensing two line-to-line voltages, the required pulse patterns for deadbeat response can be computed in real time using the predicted voltages at 9 kHz sampling frequency. This closed-loop voltage control inherently results in a very low total harmonic distortion and a very rapid transient

A. Kawamura; K. Ishihara

1988-01-01

115

Plasmas in saline solutions sustained using rectified ac voltages: polarity and frequency effects on the discharge behaviour  

NASA Astrophysics Data System (ADS)

In this work, three major problems, namely severe electrode damage, poor plasma stability and excess power consumption, arising in ac-driven plasmas in saline solutions are solved using a rectified power source. Diagnostic studies on the effects of power source polarity and frequency on the plasma behaviour are performed. Examination of I-V characteristics and temporally resolved light emission shows that the polarity significantly influences the current amplitude when the plasma exists, while the frequency alters the bubble dynamics, which in turn affects the plasma ignition voltage. When the plasma is driven by a rectified ac power source, the electrode erosion is reduced substantially. With a low frequency, moderate applied voltage and positively rectified ac power source (e.g. 100 Hz and 350 V), a stable plasma is ignited in nearly every power cycle.

Chang, Hung-wen; Hsu, Cheng-che

2012-06-01

116

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

DOEpatents

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

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

1994-01-01

117

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

DOEpatents

A high voltage accelerating potential, which is supplied by a high voltage direct current power supply, is applied to the electrically conducting interior wall of an RF powered glow discharge cell. The RF power supply desirably is electrically grounded, and the conductor carrying the RF power to the sample held by the probe is desirably shielded completely excepting only the conductor's terminal point of contact with the sample. The high voltage DC accelerating potential is not supplied to the sample. A high voltage capacitance is electrically connected in series between the sample on the one hand and the RF power supply and an impedance matching network on the other hand. The high voltage capacitance isolates the high DC voltage from the RF electronics, while the RF potential is passed across the high voltage capacitance to the plasma. An inductor protects at least the RF power supply, and desirably the impedance matching network as well, from a short that might occur across the high voltage capacitance. The discharge cell and the probe which holds the sample are configured and disposed to prevent the probe's components, which are maintained at ground potential, from bridging between the relatively low vacuum region in communication with the glow discharge maintained within the cell on the one hand, and the relatively high vacuum region surrounding the probe and cell on the other hand. The probe and cell also are configured and disposed to prevent the probe's components from electrically shorting the cell's components. 11 figures.

Duckworth, D.C.; Marcus, R.K.; Donohue, D.L.; Lewis, T.A.

1994-06-28

118

The optical response of liquid crystal cells to a low frequency driving voltage  

Microsoft Academic Search

voltage of 0.1Hz. It is found that there are predominately three physical phenomena that dominate the overall properties of the device. The first is the discharging effect whereby the effective voltage over the liquid crystal layer decreases as a function of time and occurs due to mobile ions being present within the liquid crystal material. That of the second is

Stephen Palmer

1998-01-01

119

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

120

Elastic wave propagation in sinusoidally corrugated waveguides.  

PubMed

The ultrasonic wave propagation in sinusoidally corrugated waveguides is studied in this paper. Periodically corrugated waveguides are gaining popularity in the field of vibration control and for designing structures with desired acoustic band gaps. Currently only numerical method (Boundary Element Method or Finite Element Method) based packages (e.g., PZFlex) are in principle capable of modeling ultrasonic fields in complex structures with rapid change of curvatures at the interfaces and boundaries but no analyses have been reported. However, the packages are very CPU intensive; it requires a huge amount of computation memory and time for its execution. In this paper a new semi-analytical technique called Distributed Point Source Method (DPSM) is used to model the ultrasonic field in sinusoidally corrugated waveguides immersed in water where the interface curvature changes rapidly. DPSM results are compared with analytical solutions. It is found that when a narrow ultrasonic beam hits the corrugation peaks at an angle, the wave propagates in the backward direction in waveguides with high corrugation depth. However, in waveguides with small corrugation the wave propagates in the forward direction. The forward and backward propagation phenomenon is found to be independent of the signal frequency and depends on the degree of corrugation. PMID:16642814

Banerjee, Sourav; Kundu, Tribikram

2006-04-01

121

The effect of high voltage, high frequency pulsed electric field on slain ovine cortical bone.  

PubMed

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

2014-04-01

122

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

E-print Network

requires highly linear sinusoidal-wave as the reference clock. Moreover, the generated sinusoidal signals should be tunable within the frequency range from 10kHz to 10MHz, and quadrature outputs are demanded for coherent demodulation within the system. A...

Yan, Jun

2012-07-16

123

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

Microsoft Academic Search

Rather than using a conventional Faraday modulator, this study adopts a liquid-crystal based rotator to modulate the azimuth of the linear polarized light in a sinusoidal signal for the measurement of glucose concentrations. The tilt angle of the LC director would vary as a sinusoidal-like function; however the modulating frequency in the sensing system is the double of the driving

Yu-Lung Lo; Tsung-Chih Yu

2006-01-01

124

Adaptive robust control of a class of uncertain nonlinear systems with unknown sinusoidal disturbances  

Microsoft Academic Search

In this paper, nonlinear observers are incorporated into the discontinuous projection based adaptive robust control (ARC) to synthesize performance oriented controllers for a class of uncertain nonlinear systems with unknown sinusoidal disturbances. In addition to magnitudes and phases, frequencies of the sinusoidal disturbances need not to be known as well, so long as the overall order is known. A nonlinear

Xiangbin Liu; Hongye Su; Bin Yao; Jian Chu

2008-01-01

125

Micromagnetic Simulation of Damped Oscillatory Behavior of Domain Wall Propagation in Sinusoidal Ferromagnetic Nanowire  

Microsoft Academic Search

We have investigated a damped oscillatory behavior of domain wall propagation in wavy nanowires under an external field higher than the Walker breakdown field using micromagnetic simulation. In nanowires having sinusoidal edge distortions with variation of wavelengths, domain wall has been observed to pseudomorphically follow the sinusoidal wires with keeping an intrinsic transformational frequency of inner wall spin structure. Oscillation

H.-G. Piao; J.-H. Shim; D. Djuhana; S.-H. Lee; S.-H. Jun; C.-M. Heo; S.-K. Oh; S.-C. Yu; D.-H. Kim

2010-01-01

126

A novel ISAR jamming method based on randomly sinusoidal phase modulation  

Microsoft Academic Search

In order to jamming ISAR imaging effectively, a novel jamming method based on randomly sinusoidal phase modulation is presented in this paper. This method changes randomly the frequency of the signal of sinusoidal phase modulation in the slow time. How the jamming signal affects the range alignment of ISAR is analyzed in detail. The research result shows that the jamming

Zhu Ben-yu; Xue Lei; Liu Yue-ping

2010-01-01

127

A General Model of the Laminated Steel Losses in Electric Motors with PWM Voltage Supply  

Microsoft Academic Search

A procedure is described for identifying a general mathematical model of core losses in ferromagnetic steel when the voltage supply is non-sinusoidal, i.e. PWM inverter-fed type. This model has a hysteresis loss multiplicative coefficient variable with frequency and induction and a combined coefficient for eddy-current and excess losses that is also variable with frequency and induction. The effect of the

Dan Ionel; Mircea Popescu; C. Cossar; M. I. McGilp; A. Boglietti; A. Cavagnino

2008-01-01

128

Dynamic power management of voltage-frequency island partitioned Networks-on-Chip using Intel's Single-chip Cloud Computer  

Microsoft Academic Search

Continuous technology scaling has enabled the integration of multiple cores on the same chip. To overcome the disadvantages of buses, the Network-on-Chip (NoC) architecture has been proposed as a new communication paradigm. To further mitigate the tradeoff between performance and power consumption, dynamic voltage and frequency scaling (DVFS) became the de facto approach in multi-core design. DVFS-based NoC communication was

Radu David; Paul Bogdan; Radu Marculescu; Umit Ogras

2011-01-01

129

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

130

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

131

High-Frequency Resonant SEPIC Converter With Wide Input and Output Voltage Ranges  

E-print Network

This paper presents a resonant single-ended-primary-inductor-converter (SEPIC) converter and control method suitable for high frequency (HF) and very high frequency (VHF) dc-dc power conversion. The proposed design provides ...

Hu, Jingying

132

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

133

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

E-print Network

TER-06-25 SPC-06-72 Application of Matrix Converter to Low-Voltage and Large-Current DC Power to excite the step down transformer from a three-phase utility power source. Computer simulation results. , KeywordsDC power supply, low-voltage and large-current, high-frequency transformer, leakage inductance

Fujimoto, Hiroshi

134

Development of Low-Voltage and Large-Current DC Power Supply with High-Frequency Transformer Coupling  

NASA Astrophysics Data System (ADS)

This paper describes low-voltage and large-current DC power supplies with a high-frequency transformer coupling. Two different power supplies were developed with different configurations and operation characteristics of the two were experimentally examined in this paper. Both power supplies are simply composed of a full-bridge inverter, an amorphous-core step down transformer and a schottky diode rectifier. One power supply operates on the magnetizing frequency of 15kHz, and generates 13-V and 5000-A output. The other generates 12-V and 4000-A output, but introduces only 1-kHz magnetizing frequency due to a long overlapping period in commutation caused by large leakage inductance of its transformer. The maximum total efficiency of the former and the latter is 89.9% and 85.7%, and the total input power factor of the two is 83.5% and 92.8%, respectively. Although the output voltages and currents of the two prototypes are considerably low and large, these experimental results demonstrate excellent performance.

Noguchi, Toshihiko; Nishiyama, Kosuke; Ishida, Keiichi; Asai, Yoshihisa; Matsubara, Toru

135

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

PubMed Central

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. PMID:21808425

Y?ld?z, D. E.; Dökme, ?.

2011-01-01

136

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

DOEpatents

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

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

1994-01-01

137

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

138

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

NASA Astrophysics Data System (ADS)

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

2014-02-01

139

Steady-state sinusoidal thermal characterization at chip level by internal infrared-laser deflection  

NASA Astrophysics Data System (ADS)

A new approach is reported for thermally characterizing microelectronic devices and integrated circuits under a steady-state sinusoidal regime by internal infrared-laser deflection (IIR-LD). It consists of extracting the amplitude and phase Bode plots of the temperature profile inside the chip (depth-resolved measurements in the frequency domain). As a consequence, not only are the IIR-LD performances significantly improved (accuracy, robustness to noise, control of boundary conditions and heat flux confinement) but also the direct temperature measurement is feasible when thin regions are inspected and thermal parameters can be easily extracted (thermal diffusivity). In order to show the efficiency of this technique, a thermal test chip (TTC) is used. The TTC is thermally excited by imposing a cosine-like voltage waveform. As a result, a vertical temperature profile inside the die is obtained depending on the heating frequency. Repeating this procedure at several frequencies, the frequency response of the chip internal temperature profile is derived. By comparing the experimental results with the model predictions, good agreement is achieved. This technique allows evaluation of the thermal behaviour at the chip level; also it could be useful for failure analysis.

Perpiñà, Xavier; Jordà, Xavier; Vellvehi, Miquel; Altet, Josep; Mestres, Narcís

2008-08-01

140

Induction Motor Operation With Non-Sinusoidal Impressed Voltages  

Microsoft Academic Search

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

L. A. Doggett; E. R. Queer

1929-01-01

141

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

142

Propulsion by sinusoidal locomotion: A motion inspired by Caenorhabditis elegans  

NASA Astrophysics Data System (ADS)

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

Ulrich, Xialing

143

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

144

IEEE International Conference on Power and Energy (PECon 08), December 1-3, 2008, Johor Baharu, Malaysia Variable High Frequency Voltage Source for an  

E-print Network

. The rate of ohmic heating critically depends on the Electrical Conductivity of the food during the process; Electrical Conductivity; Power Electronics; High Frequency; Electrolyze; Oxidation I. INTRODUCTION Heating, Malaysia Variable High Frequency Voltage Source for an Ohmic Heating Process A. Toudeshki, N. Mariun SMIEEE

Hammerton, James

145

Sinusoidal analysis of electroretinogram of squid and octopus.  

PubMed

1. An isolated eye or eye plus optic lobe preparation (in oxygenated chilled seawater) from Loligo opalescens, Octopus bimaculata, and O. bimaculoides was used to study the electroretinogram (ERG) for small signal intensity-modulated stationary spots of light. 2. If light intensity was modulated sinusoidally (modulation depth 0-50%) the ERG response is sinusoidal with less than 2% of the power present in the next five harmonics compared to the fundamental. Bode plots, amplitude and phase shift plotted against frequency, were constructed from these sinusoidal input-output experiments. 3. Linearity and time invariance were tested: a) an increase in amplitude of sinusoidal modulation by a constant factor caused an increase in response amplitude by the same factor but caused no change in shape of the Bode plot gain or phase curves; b) the transfer function represented by the Bode plot could be used to predict waveshape of the response to a brief flash (Green's or impulse-response function); c) the Fourier transformed square-wave response could be used to obtain a Bode plot which coincided with that obtained by sinusoidal input-output experiments. 4. The Bode plot can be fit by the transfer function of 5-12 (depending on conditions and on the preparations) series cascaded low-pass filters whose corner frequences are distributed between 0.2 and 40 Hz. Alternatively, 3-7 filters plus a delay of 25-130 ms fits the Bode plots equally well. The series filter model is compatible with a simply physical model consisting of cascaded chemical reactions whose forward rate constants are reciprocals of the filter time constants, whose reverse rate constants are negligible, and in which the concentration of an intermediate product controls membrane current. 5. As mean intensity is increased, the gain decreases. This effect is more pronounced at low frequencies than at high frequencies. Thus, the system is nonlinear for large intensity changes. The process of adaptation involves not only a change in gain, but a change in shape of the Bode plot, i.e., change in filter corner frequencies. In terms of the reaction chain model, this means that some rate constants change as the state of adaptation is changed. PMID:833626

Hartline, P H; Lange, G D

1977-01-01

146

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

E-print Network

the reflection of the modulated source from a cavity. If the source is slightly detuned from a resonance controlled oscillator to a cavity resonance at 800 MHz using the Pound-Drever-Hall method. This technique to optical cavity resonances. It was originally developed by Pound1 for the frequency stabiliza- tion

Le Roy, Robert J.

147

Radio-Frequency Interference (RFI) From Extra-High-Voltage (EHV) Transmission Lines  

E-print Network

Book (2008) recognizes the BPA method because The most complete empirical method for predicting EMI expanded so that EMI above 30 MHz can be calculated at any frequency, at any distance from the line, at any for EMI predictions between 30 and 1000 MHz" and "the most complete empirical method for predicting EMI

Ellingson, Steven W.

148

Low Switching Frequency Active Harmonic Elimination in Multilevel Converters with Unequal DC Voltages  

E-print Network

method for the cascaded H-bridges multilevel converter when supplied by unequal DC sources. FirstLow Switching Frequency Active Harmonic Elimination in Multilevel Converters with Unequal DC, the multilevel converter is decoupled into individual unipolar converters, and the low order harmonics (such

Tolbert, Leon M.

149

Skin profiles during sinusoidal vibration of the fingerpad.  

PubMed

Skin on the fingertips of humans and monkeys was stimulated by a probe vibrating with a sinusoidal displacement. The probe and the skin were illuminated stroboscopically and were viewed through a dissecting microscope. The stroboscope was triggered by the sinusoidal generator via a digital delay, so that the position of both the probe and the skin could be measured at regular intervals during the cycle. Six frequencies and 3 amplitudes of vibration were used. During a portion of the cycle the probe and the skin separated, so that the skin waveform was a clipped sinusoid. An increase in stimulus frequency increased the fraction of the cycle during which the probe and the skin were separated. Adding a static pre-indentation to the vibration reduced this fraction, and for this condition a decrease in vibratory amplitude also decreased the fraction. Thus the skin motion contained harmonics that were not present in the probe motion, and the harmonic content differed for different stimulus conditions. PMID:2792271

Goodwin, A W; John, K T; Darian-Smith, I

1989-01-01

150

Resistance and Venous Oxygen Dynamics during Sinusoidal Exercise of Dog Skeletal Muscle  

Microsoft Academic Search

We observed the response of vascular resistance and venous oxygen (O2) satu- ration to sinusoidally modulated continuous exercise of the isolated dog calf. Stimulus frequency was varied sinusoidally between 0.5 Hz and 1 Hz with modulation fre- quencies ranging from 0.005 Hz to 0.05 Hz. Venous O2 responses were corrected for dispersion due to vascular and catheter transit. As modulation

David E. Mohrman; Harvey V. Sparks

151

IEEE TRANSACTIONS ON SPEECH AND AUDIO PROCESSING, VOL. 11, NO. 5, SEPTEMBER 2003 413 Matching Pursuits Sinusoidal Speech Coding  

E-print Network

for each sinusoidal component are sequentially extracted by a closed-loop analysis. The sinusoidal modeling or bins, which in conjunction with the closed-loop analysis allow us to map the frequenciesIEEE TRANSACTIONS ON SPEECH AND AUDIO PROCESSING, VOL. 11, NO. 5, SEPTEMBER 2003 413 Matching

California at Santa Barbara, University of

152

Influence of High-Frequency Charge–Discharge Cycling Induced by Cell Voltage Equalizers on the Life Performance of Lithium-Ion Cells  

Microsoft Academic Search

Various types of cell voltage equalizers that exchange charges among cells have been proposed for series-connected lithium-ion cells. During equalization, cells are possibly cycled not only over a conventional period that ranges from seconds to hours but at a high frequency that is equal to the operating frequency of the equalizers as well. This paper investigates how the high-frequency cycling

Masatoshi Uno; Koji Tanaka

2011-01-01

153

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

Microsoft Academic Search

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

Jia Wei; Fred C. Lee

2003-01-01

154

All-polymer modulator for high frequency low drive voltage applications  

NASA Astrophysics Data System (ADS)

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

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

2013-03-01

155

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

SciTech Connect

A battery is commonly assumed to be a huge capacitor and behave as a capacitor toward AC signals on connected lines. The effect of such capacitance is important to designers of connected power electronics apparatus, so we decided to attempt to measure this effect by forcing alternating currents at selected frequencies from 10 Hz to 20 kHz through the battery with a power amplifier. The inducement to make the measurements was the result of an interest in possible internal impedances differences, between flooded electrolyte cells, and the emerging developments in immobilized electrolyte cell construction.

Hodgson, R.L.; Oman, H.

1984-08-01

156

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

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

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

PubMed

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

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

2008-09-01

159

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

NASA Astrophysics Data System (ADS)

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

2008-09-01

160

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

161

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

PubMed

Abstract 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 electrical stunning frequency and voltage combinations on the presence of engorged blood vessels in goose liver.  

PubMed

The purpose of this study was to investigate the influence of nine electrical stunning methods using various frequency and voltage combinations on the occurrence of engorged blood vessels in goose liver. Two hundred seventy Gourmaud geese (liver-type line SI 14) were slaughtered at 12 wk of age, in groups of 90 at three different times. Thirty birds each were subjected to one of the nine stunning methods. Neck cutting was performed immediately after stunning. The duration of exsanguination was 11 min. After completion of bleeding, the birds were scalded, defeathered manually, and kept refrigerated. At 1 d postmortem, the carcasses were eviscerated and cut up. From the slaughterhouse, the livers chilled in ice were transported to the cannery where they were weighed and graded at 2 d postmortem and were further processed. All of the veins and capillaries full of blood were removed from livers, because their presence was a hazard to product quality by causing discoloration of the canned liver, and the percentage of liver weight loss was then determined. The loss in liver weight due to removal of engorged blood vessels was reduced (P < 0.05) at 350 Hz, 70 to 90 V, and 80 to 85 mA when compared to the results obtained with any other stunning method tested. It was concluded that the use of high-frequency currents for electrical stunning of liver geese might have considerable commercial advantages. PMID:14653479

Turcsán, Zs; Varga, L; Szigeti, J; Turcsán, J; Csurák, I; Szalai, M

2003-11-01

163

High amplitude sinusoidal pressure generator  

NASA Technical Reports Server (NTRS)

Generator is an inlet-area-modulated, gas-flow-through device utilizing hydrogen gas and a rotating disk for operation. Design enables generator to produce pressure oscillations as high as 120, 18, and 12 percent of the mean chamber pressure at frequencies of 1, 10, and 15 kHz, respectively.

Robinson, R. E.

1970-01-01

164

A note on Bragg scattering of surface waves by sinusoidal bars James T. Kirby  

E-print Network

to the resonant frequency. For finite detuning away from the resonant frequency, two previous solutions are shown to the resonant condition, where the bar wave number is twice the wave-number component of the surface wave of perfectly sinusoidal bars. The resonant reflection solution of Mei proceeds by assuming that the waves

Kirby, James T.

165

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

NASA Astrophysics Data System (ADS)

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

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

2013-06-01

166

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

167

False Operation of Static Random Access Memory Cells under Alternating Current Power Supply Voltage Variation  

NASA Astrophysics Data System (ADS)

Static random access memory (SRAM) cores exhibit susceptibility against power supply voltage variation. False operation is investigated among SRAM cells under sinusoidal voltage variation on power lines introduced by direct RF power injection. A standard SRAM core of 16 kbyte in a 90 nm 1.5 V technology is diagnosed with built-in self test and on-die noise monitor techniques. The sensitivity of bit error rate is shown to be high against the frequency of injected voltage variation, while it is not greatly influenced by the difference in frequency and phase against SRAM clocking. It is also observed that the distribution of false bits is substantially random in a cell array.

Sawada, Takuya; Takata, Hidehiro; Nii, Koji; Nagata, Makoto

2013-04-01

168

Rectification of confined diffusion driven by a sinusoidal force  

NASA Astrophysics Data System (ADS)

A particle diffusing in an asymmetric periodic channel, driven by a sinusoidal force F(t )=F0cos?t (the rocking ratchet) is considered. The asymptotic solution of the generalized Fick-Jacobs equation describing the system is studied in the nonadiabatic regime. The leading term of the rectified current, appearing in the order ˜F02, is derived. The method presented enables us to solve the problem analytically for a sawtooth channel and also to look for approximative formulas applicable in a wide range of frequencies ?. Even the simplest approximation qualitatively reproduces the current reversal at higher frequencies as the result of growing phase lag of the rocking density behind the driving force.

Kalinay, Pavol

2014-04-01

169

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

170

A Generation Control of Arbitrary AC Waveforms for the Single-phase Voltage Source PWM Inverter Utilizing an Adaptive Frequency Loss-less Resonator  

NASA Astrophysics Data System (ADS)

Power supplies used on the electric power environment test process for electronic products and audio-amplifiers are required to generate arbitrary ac voltage waveforms in the wide frequency range. Traditionally, analogue amplifier technologies have been used for those application even though those have the disadvantages of low-efficiency, bulky in volume, and heavy in weight. Recently, however, research on the arbitrary waveform power generator becomes to be attractive among power electronics engineers, because the audio amplifiers utilizes the D-Mode switching technologies have been move into the market. This paper presents an arbitrary ac power generator utilizes a novel instantaneous waveform control method for a single-phase voltage source PWM inverter. A remarkable feature of this control method is that an adaptive frequency band-pass filter based on a rotation frame transformation and a command generator on the rotation frame is used. The proposed method can suppress the resonance caused by the LC filter at the output line, and hence it enables to generate a rectangular voltage waveform without overshoot. The command generator generates both an instantaneous frame angle and accurate voltage commands on the rotating frame from one an analogue signal. The effectiveness of this method is verified through 500W experimental set-up.

Hashino, Satoshi; Wada, Keiji; Shimizu, Toshihisa

171

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

172

Sinusoidal analysis of Space Shuttle Main Engine structures  

Microsoft Academic Search

Turbopumps in the Space Shuttle Main Engine (SSME) generate sinusoidal vibrations due to imbalance of the rotating components. Since the true forcing functions necessary for sinusoidal analysis are difficult to formulate, a combined experimental\\/analytical technique is developed. The technique predicts the peak sinusoidal stresses in SSME structures using excitations prescribed at base points. This paper presents the technique and procedures

L. K. Shen

1994-01-01

173

Analysis and realization of a pulsewidth modulator based on voltage space vectors  

Microsoft Academic Search

A space vector concept for deriving the switching times for pulsewidth-modulated voltage source inverters is compared with the conventional sinusoidal concept. The switching times are deducted from assumptions for minimum current distortion, the resulting mean voltage values are shown, and the differences between these and the established sinusoidal PWM (pulse-width modulator) are elaborated. Based on an analytical calculation the current

H. W. van der Broeck; H.-C. Skudelny; G. V. Stanke

1988-01-01

174

Evaluation of the otolith function using sinusoidal off-vertical axis rotation in patients with benign paroxysmal positional vertigo  

Microsoft Academic Search

The vestibulo-ocular reflex (VOR) was studied via sinusoidal off-vertical axis rotation (OVAR) to evaluate the otolith function in patients with benign paroxysmal positional vertigo (BPPV). Subjects were sinusoidally rotated with eyes open in complete darkness at frequencies of 0.4 and 0.8Hz with a maximum angular velocity of 60°s?1 in earth-vertical axis rotation (EVAR) and OVAR. Twenty-three controls and 24 BPPV

Akemi Sugita-Kitajima; Miki Azuma; Kosuke Hattori; Izumi Koizuka

2007-01-01

175

79 FR 11097 - Third-Party Provision of Reactive Supply and Voltage Control and Regulation and Frequency...  

Federal Register 2010, 2011, 2012, 2013, 2014

...9\\ Frequency response involves the autonomous, automatic, and rapid reaction of...Commission found that governor-based autonomous frequency response did not merit a...response is provided by the automatic and autonomous actions of turbine-generators...

2014-02-27

176

The application of all-pass filters in the design of multiphase sinusoidal systems  

Microsoft Academic Search

The design of even and odd phase sinusoidal systems using all-pass networks is presented. The all-pass network has the unique characteristic of unity gain at all frequencies and a frequency-dependent phase relationship between output and input. It produces up to 180° phase shift which allows the easy implementation of multiphase systems. The network is implemented using the widely available operational

S. J. G Gift

2000-01-01

177

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

178

Voltage Divider  

NSDL National Science Digital Library

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

179

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

180

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

181

Development of Low-Voltage and Large Current DC Power Supply with High-Frequency Transformer Coupling  

E-print Network

-5000A 1-40 #12;Table 2. Specifications of high-frequency step down transformer of 13V-5000A DC power. 4. Cross section diagram of high-frequency step down transformer of 13V-5000A DC power supplyINV To DC exitation surpression circuit #2 iINV D1 D2 Table 3. Specifications of high-frequency step down

Fujimoto, Hiroshi

182

Spur-reduced digital sinusoid synthesis  

NASA Technical Reports Server (NTRS)

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

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

1993-01-01

183

[Pathology along the liver sinusoids: intrasinusoidal findings].  

PubMed

Pathological findings in the liver sinusoids are mostly caused by extrahepatic or systemic diseases. Unclear fever, hepatosplenomegaly, portal hypertension or a mild elevation of liver enzymes are reasons for a liver biopsy leading to path-breaking diagnoses. Reactive intrasinusoidal lymphocytosis, especially with Epstein-Barr virus infections, has to be differentiated from predominantly intrasinusoidal lymphoproliferative malignancies. Intrasinusoidal megakaryocytes can be the first sign of a myeloproliferative or myelodestructive disease. Intrasinusoidal carcinosis and melanomatosis might present radiologically without tumor lesions and are easily overlooked histologically, in particular, if the critical cells have a similar size to hepatocytes. This also applies for intrasinusoidal storing macrophages. Gaucher's disease type I, and some other subtypes of inborn storage diseases might present for the first time in adulthood by hepatomegaly and Kupffer cell hypertrophy. Accompanying perisinusoidal fibrosis and immunohistochemical staining (CD68) can help to detect the large pale intrasinusoidal macrophages. In immunocompromized patients with fever, particular attention must be paid to intracellular agents, especially atypical mycobacteria and yeasts in non-granulomatous nested or dispersed Kupffer cells. Leishmaniasis with amastigotes in macrophages is accompanied by reactive sinusoidal plasmocytosis. PMID:18210115

Flucke, U; Fischer, H-P

2008-02-01

184

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

185

Experimental and analytical study of sinusoidal buckling in vertical wells  

SciTech Connect

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

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

1994-12-31

186

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

187

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

E-print Network

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 ...

Garrison, Sean Michael

2009-05-22

188

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

NASA Astrophysics Data System (ADS)

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

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

2009-09-01

189

Analytical analysis of the Pennes bioheat transfer equation with sinusoidal heat flux condition on skin surface.  

PubMed

This study focuses on the effect of the temperature response of a semi-infinite biological tissue due to a sinusoidal heat flux at the skin. The Pennes bioheat transfer equation such as rho(t)c(t)( partial differentialT/ partial differentialt)+W(b)c(b)(T-T(a))=k partial differential(2)T/ partial differentialx(2) with the oscillatory heat flux boundary condition such as q(0,t)=q(0)e(iomegat) was investigated. By using the Laplace transform, the analytical solution of the Pennes bioheat transfer equation with surface sinusoidal heating condition is found. This analytical expression is suitable for describing the transient temperature response of tissue for the whole time domain from the starting periodic oscillation to the final steady periodic oscillation. The results show that the temperature oscillation due to the sinusoidal heating on the skin surface is unstable in the initial period. Further, it is unavailable to predict the blood perfusion rate via the phase shifting between the surface heat flux and the surface temperature. Moreover, the lower frequency of sinusoidal heat flux on the skin surface induces a more sensitive phase shift response to the blood perfusion rate change, but extends the beginning time of sampling because of the avoidance of the unavailable first cyclic oscillation. PMID:17137825

Shih, Tzu-Ching; Yuan, Ping; Lin, Win-Li; Kou, Hong-Sen

2007-11-01

190

Maximum likelihood estimation of the parameters of multiple sinusoids from noisy measurements  

Microsoft Academic Search

The problem of estimating the frequencies, phases, and amplitudes of sinusoidal signals is considered. A simplified maximum-likelihood Gauss-Newton algorithm which provides asymptotically efficient estimates of these parameters is proposed. Initial estimates for this algorithm are obtained by a variation of the overdetermined Yule-Walker method and periodogram-based procedure. Use of the maximum-likelihood Gauss-Newton algorithm is not, however, limited to this particular

PETRE STOICA; RANDOLPH L. MOSES; BENJAMIN FRIEDLANDER; TORSTEN SODERSTROM

1989-01-01

191

Dead-Space Theory Predictions of Excess-Noise Factor, Breakdown Voltage, and Frequency Response for Thin Avalanche Photodiodes  

E-print Network

multiplication theory properly predicts the reduction in the excess noise factor in a number of APDs. The theoryP, InAlAs, GaAs, and A1GaAs APDs with multiplication- region widths ranging from 80 nm to 1600 nm breakdown down, frequency response. 1 Introduction It is well known that for avalanche photodiodes (APDs

Teich, Malvin C.

192

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

193

Electrical and mechanical properties of the crustacean stretch receptor during sinusoidal length changes.  

PubMed

Isolated slowly adapting stretch receptors of the crayfish (Astacus fluviatilis) were exposed to sinusoidal length changes. The mechanical force, the receptor current and the receptor potential were analysed in terms of frequency response (Bode plots) and input/output functions. Within the frequency range investigated (0.3 to 80 Hz) the mechanical force was found to be only slightly dependent on the frequency of the sinusoidal stimuli, the slope of the gain function in the Bode plot being close to zero. Dynamic length-force curves exhibited a characteristic hysteresis. In potential clamp experiments, the receptor current induced by sinusoidal length changes was dependent on the clamp potential attaining maximal amplitude at a membrane potential of about -20 to -30 mV for 80 Hz mechanical stimulation. The membrane potential at which the receptor current changed sign (the reversal potential) increased with increasing frequency. In Bode plots of the receptor current the gain was represented by a straight line, having a slope of about 1.2 dB/octave. The phase shift was positive at low frequencies. Bode plots of the receptor potential gain exhibited a characteristic peak in the region of 15 Hz. Below this peak the gain increased with about 1.2 dB/oct, above the peak the gain decreased with about 4.8 dB/oct. There was a small positive phase shift at low frequencies; at high frequencies the phase shift became negative. The impedance of the cell, as calculated from the receptor potentials and the current responses at resting membrane potential, gave Bode plots comparable to a simple resistive-capacitive filter compatible with the electrical properties of the receptor cell membrane. The cut-off frequency of this low pass filter decreased with decreasing stretch amplitude. One physiological significance of this finding, is that the performance of the receptor is improved at low levels of stimulation by reducing the bandwidth of the system. PMID:6869030

Johansson, B; Rydqvist, B

1983-02-01

194

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

NASA Technical Reports Server (NTRS)

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

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

1990-01-01

195

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

NASA Technical Reports Server (NTRS)

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

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

1990-01-01

196

Frequency-dependent potentiation of voltage-activated responses only in the intact neurohypophysis of the rat  

Microsoft Academic Search

The loose-patch-clamp technique was used with multiple-pulse protocols to study the frequency dependence of currents from the surface of the intact rat neurohypophysis (NH) and hypothalamus. In the NH, but not in the corresponding supraoptic nucleus of the hypothalamus, an initial, single pulse of 3–8 ms duration (long pulse) potentiated a secondary pulse response starting 20–50 ms after the initial pulse. Potentiation

Héctor G. Marrero; José R. Lemos

2005-01-01

197

Heart rate dynamics during sinusoidal exercise: comparison of the control system between children and adults.  

PubMed

The aim was to model the dynamics of heart rate (HR) response to sinusoidal work rate (WR) forcing in children and adults. Seven pre-pubertal boys (aged 10-13) and five adult males (aged 22-37) were studied. Continuous ECG recordings were obtained during the following physiological manoeuvres: five constant amplitude ergometer exercises with WR varying sinusoidally with periods of 0.75, 1, 2, 3.5, and 5 min duration, and one step exercise at a constant WR equal to the midpoint of the sinusoid amplitude. The amplitude ratio (AR; standardized by WR) of the fundamental harmonic of the HR response and the phase shift (phi) between the WR to HR were calculated by Fourier analysis. The HR dynamic parameters (gain and time constant (tau)) of a first order model with or without delay (Td) were also estimated. The AR in children was always higher than that in adults, in absolute terms, but not as a function of body weight. The phi was more delayed in the children than the adults only for the shortest period, i.e. 0.75 min. The tau for the first order model, either without or with Td, was found to be no difference between children and adults (44.7 vs. 45.9 s (without Td), 34.9 vs. 42.3 s (with Td)). Td, however, was longer in the children (6.6 vs. 2.3 s). The goodness of fit for the first order model with Td was better than that without Td in children, i.e. due to the difference of phi for 0.75 min period, whereas the HR dynamics in adults was appropriately described by first order model without Td. It is concluded that the fundamental control of HR to sinusoidal exercise between children and adults was not appreciably different, except for a small Td difference at high sinusoidal frequency. PMID:10430461

Fukuba, Y; Haouzi, P; Chalon, B

1999-07-01

198

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

NASA Astrophysics Data System (ADS)

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

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

2012-11-01

199

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

200

Sinusoidal polynomial parameter estimation using the distribution derivative  

Microsoft Academic Search

In this paper, we present a method to estimate the parameters of a generalized sinusoidal model. A generalized sinusoid x is defined as a polynomial in the log domain, with complex coefficients alphai : x(t)=exp(Sigmai alphai t i), where i=0...Q. The method is based on the distribution derivative of the signal and operates in the transform domain. The method is

Michaël Betser

2009-01-01

201

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

202

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

203

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

SciTech Connect

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

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

2010-04-01

204

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

205

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

206

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

PubMed Central

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

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

2013-01-01

207

Vertical eye position responses to steady-state sinusoidal fore-aft head translation in monkeys.  

PubMed

A major function of the otolith organ is to detect linear acceleration generated by two different head conditions, dynamic linear translation and static tilt relative to gravity. To investigate these sensory functions of the otolith organ, we analyzed vertical eye position in response to steady-state sinusoidal fore-aft translation over a range of frequencies (0.5-4 Hz) and amplitudes (0.10-0.33 g) in three monkeys. Vertical vestibuloocular reflexes elicited by linear acceleration (LVORs) during sinusoidal fore-aft translation were divided into translational LVOR component and tilt LVOR component taking vertical gaze-dependent properties into account. Based on geometrical considerations, the translational LVOR component, but not the tilt LVOR component, depended on vertical gaze eccentricity. To quantify these two components, we used a V-shaped function model, plotting vertical eye sensitivities (deg/cm) against vertical gaze eccentricities (deg). The slope (deg/cm per degree) and intercept (sensitivity at zero gaze eccentricity) of this function approximately reflected the translational and tilt LVOR components, respectively. Our data show that the tilt LVOR component is independent of the reciprocal of the fixation distance (MA), whereas the translational LVOR component is almost linearly related to MA. The gain of the tilt LVOR component, characterized by low-pass dynamics, was greatest (0.36) at 0.5 Hz. Visual information clearly reduced the gain of the tilt LVOR component, by approximately 50%. There was no difference between the effects of large-field and small-spot stimuli. These findings demonstrate that steady-state sinusoidal fore-aft translation at lower frequencies stimulates the otolith organs and produces a pseudo-pitch tilt in cooperation with the gravito-inertial force and as a result elicits an ocular response equivalent to the tilt LVOR. PMID:17912504

Wada, Yoshiro; Kodaka, Yasushi; Kawano, Kenji

2008-02-01

208

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

209

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

210

Sinusoidal Variation of Inductance in a Linear Series RLC Circuit  

Microsoft Academic Search

Sinusoidal variation of inductance in a series RLC circuit is considered in a manner which generalizes previous treatments by placing the variation inside the differentiation sign, and by inclusion of dissipation. A simple relationship is established with solutions for capacitance variation. Dissipation is shown to lead to time-variable damping in a specified manner. Typical differential analyzer solutions are presented.

E. I. Hawthorne

1951-01-01

211

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

212

Diffusion of Chiral Janus Particles in a Sinusoidal Channel  

E-print Network

We investigate the transport diffusivity of artificial microswimmers, a.k.a. Janus particles, moving in a sinusoidal channel in the absence of external biases. Their diffusion constant turns out to be quite sensitive to the self-propulsion mechanism and the geometry of the channel compartments. Our analysis thus suggests how to best control the diffusion of active Brownian motion in confined geometries.

Xue Ao; Pulak Kumar Ghosh; Yunyun Li; Gerhard Schmid; Peter Hänggi; Fabio Marchesoni

2014-12-18

213

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

214

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

215

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.

216

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

217

High frequency induction heating load resonant inverter with voltage-clamped quasi-resonant switched using newly-improved static induction transistors\\/thyristors and their phase shifted controlled scheme  

Microsoft Academic Search

The authors discuss a resonant capacitor voltage-clamped type half-bridge topology of a novel instantaneous resonant current vector-regulated high-frequency inverter with phase-shifting control, which efficiently operates at zero-current soft-switched quasi-resonant and load resonant tank circuit subresonant hybrid soft-switching schemes. This proposed multiresonant inverter version using static induction (SI) devices (SI transistors and SI thyristors) is more suitable for a modern induction-heating

H. Ogiwara; A. Okuno; M. Nakaoka

1992-01-01

218

What is new in the liver sinusoids? meeting report, 16th International Symposium on Cells of the Hepatic Sinusoid (ISCHS)  

PubMed Central

The 16th International Symposium on Cells of the Hepatic Sinusoid (ISCHS) took place in Florence, Italy on 22-24 September 2011. This symposium is a multidisciplinary meeting where new and important findings on the biology of liver cells are presented and discussed. PMID:22166123

2011-01-01

219

Quantized voltage plateaus in Josephson-junction arrays: A numerical study  

NASA Astrophysics Data System (ADS)

We study numerically the quantized voltage plateaus in an N×N array of resistively shunted Josephson junctions subjected to a combined dc and ac applied current Idc+Iacsin(2??t), and a transverse magnetic field equal to p/q==f flux quanta per plaquette (p and q relatively prime integers). With periodic transverse boundary conditions, we find plateaus at all voltages satisfying =nNh?/(2eq), where n is an integer, and the angular brackets <...> denote a time average. With free transverse boundary conditions, additional steps at =Nh?/(4eq) sometimes appear. For f=1/5 and 2/5, we study the motion of the vortex lattice on the steps. At both fields, on every step, the lattice moves an integer number of array lattice constants per cycle of the ac field. For both zero and finite applied transverse magnetic field, the width of the steps varies sinusoidally with Iac, in a manner reminiscent of that seen in single Josephson junctions. At a given field and current, the steps ``melt'' at a temperature no higher than the transition temperature of the underlying array at the same field and zero current. On the steps, the time-dependent voltage across the array has strong harmonics at multiples of the fundamental frequency. Off the steps, the power spectrum of the voltage has an apparently broad band with possible subharmonic structure.

Lee, K. H.; Stroud, D.

1991-03-01

220

Optical characterization of a dual-frequency hybrid aligned nematic liquid crystal cell  

NASA Astrophysics Data System (ADS)

The dielectric anisotropy of a highly dispersive dual-frequency nematic liquid crystal (MDA-00-3969 (Merck KGa)) has been determined using the optical fully-leaky guided-mode technique. A 4Vrms sinusoidal voltage was applied across a 5µm hybrid aligned nematic (HAN) cell at various frequencies in both the positive and negative dielectric anisotropy regime. Optical data was collected at each frequency enabling the director profile in each case to be determined using a multi-layer optics model in combination with a liquid crystal free-energy minimization routine. The thresholdless response of the HAN cell combined with the extreme sensitivity of the optical characterization technique has allowed subtle changes in dielectric permittivity with frequency to be observed. The resulting measured dispersion shows excellent agreement with a single Debye-type relaxation model.

Jewell, S. A.; Sambles, J. R.

2005-04-01

221

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

222

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

223

Sinusoidal input describing function for hysteresis followed by elementary backlash  

NASA Technical Reports Server (NTRS)

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

Ringland, R. F.

1976-01-01

224

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

225

Investigation of Calibrating Force Transducer Using Sinusoidal Force  

SciTech Connect

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

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

2010-05-28

226

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.

227

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

228

Diffusion of chiral Janus particles in a sinusoidal channel  

NASA Astrophysics Data System (ADS)

We investigated the transport diffusivity of artificial microswimmers, a.k.a. Janus particles, in the absence of external biases. We considered the case of chiral Janus particles moving either in the bulk or in sinusoidal channels with reflecting walls. Their self-diffusion constants turned out to depend on both the strength and the chirality of the self-propulsion mechanism. More importantly, in a periodic channel self-diffusion can be controlled by tailoring the compartment geometry.

Ao, Xue; Ghosh, P. K.; Li, Y.; Schmid, G.; Hänggi, P.; Marchesoni, F.

2015-01-01

229

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

230

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

PubMed

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

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

2014-01-01

231

Mold non-sinusoidal oscillating mode analyse and control of continuous casting machine  

Microsoft Academic Search

The way of mould oscillation and the parameter of oscillation have the great influence on the improving casting speed and the quality of the casting billet surface. The paper mainly introduced the regulation of non-sinusoidal oscillating, comparing with the sinusoidal regulation, analyzed the advantage of non-sinusoidal oscillating regulation. And the paper introduced the technology of mould oscillation and the characteristics

Wentao Li; Yuan Zhang; Lei Yu; Junsheng Xiao

2009-01-01

232

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

PubMed Central

This review provides a detailed overview of the current state of knowledge about the ultrastructure and dynamics of liver sinusoidal endothelial fenestrae. Various aspects of liver sinusoidal endothelial fenestrae regarding their structure, origin, species specificity, dynamics and formation will be explored. In addition, the role of liver sinusoidal endothelial fenestrae in relation to lipoprotein metabolism, fibrosis and cancer will be approached. PMID:12437787

Braet, Filip; Wisse, Eddie

2002-01-01

233

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.

234

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

NASA Technical Reports Server (NTRS)

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

Drischler, Joseph A

1956-01-01

235

Modelling of a hydraulic engine mount focusing on response to sinusoidal and composite excitations  

NASA Astrophysics Data System (ADS)

Frequency response characteristics of a hydraulic engine mount are investigated. The mount studied is highly non-linear due to an amplitude-limited floating piston (the "decoupler") which enables the response to large amplitude (typically road-induced) excitations to differ markedly from the response to small amplitude (typically engine-induced) excitations. The effect of the decoupler on frequency response as well as composite-input (sum of two sinusoids) response is considered. New experimental data for a production mount and several specially prepared mounts are presented and discussed. Two linear models, one for large amplitude excitations and one for small amplitude excitations, are developed and shown to be effective over a 5-200 Hz frequency range. The latter model explains a moderately high frequency (? 120 Hz) resonance which is often observed in the data, but which has not previously been described in physical terms. A piecewise linear simulation and an equivalent linearization technique are used to explain the amplitude-dependence of frequency response, as well as the composite-input response. The applicability of equivalent linearization is justified by demonstrating that high order harmonics contribute very little to the transmitted force. Moreover, this technique is found to be computationally efficient and to provide insight into decoupler dynamics.

Colgate, J. E.; Chang, C.-T.; Chiou, Y.-C.; Liu, W. K.; Keer, L. M.

1995-07-01

236

Analysis on voltage distribution performance of HVDC thyristor valves  

Microsoft Academic Search

Analysis and simulation on voltage distribution of HVDC thyristor valves under a variety of voltage stress are performed respectively. The summarized influencing factors on voltage distribution indicate that they are different with frequency. Due to the importance and difficulty in approaching even distribution in high frequency, the voltage distribution with different module structure and different power circuit parameters is also

H. Guo; G. F. Tang; J. L. Wen; K. P. Zha; X. G. Wei

2010-01-01

237

ERG voltage-gated K+ channels regulate excitability and discharge dynamics of the medial vestibular nucleus neurones  

PubMed Central

The discharge properties of the medial vestibular nucleus neurones (MVNn) critically depend on the activity of several ion channel types. In this study we show, immunohistochemically, that the voltage-gated K+ channels ERG1A, ERG1B, ERG2 and ERG3 are highly expressed within the vestibular nuclei of P10 and P60 mice. The role played by these channels in the spike-generating mechanisms of the MVNn and in temporal information processing was investigated electrophysiologically from mouse brain slices, in vitro, by analysing the spontaneous discharge and the response to square-, ramp- and sinusoid-like intracellular DC current injections in extracellular and whole-cell patch-clamp studies. We show that more than half of the recorded MVNn were responsive to ERG channel block (WAY-123,398, E4031), displaying an increase in spontaneous activity and discharge irregularity. The response to step and ramp current injection was also modified by ERG block showing a reduction of first spike latency, enhancement of discharge rate and reduction of the slow spike-frequency adaptation process. ERG channels influence the interspike slope without affecting the spike shape. Moreover, in response to sinusoid-like current, ERG channel block caused frequency-dependent gain enhancement and phase-lead shift. Taken together, the data demonstrate that ERG channels control the excitability of MVNn, their discharge regularity and probably their resonance properties. PMID:18718985

Pessia, Mauro; Servettini, Ilenio; Panichi, Roberto; Guasti, Leonardo; Grassi, Silvarosa; Arcangeli, Annarosa; Wanke, Enzo; Pettorossi, Vito Enrico

2008-01-01

238

User-and Process-Driven Dynamic Voltage and Frequency Scaling Bin Lin Arindam Mallik Peter Dinda Gokhan Memik Robert Dick  

E-print Network

): user-driven frequency scaling (UDFS) and process-driven volt- age scaling (PDVS). In PDVS, a CPU.9% UDFS), with a maxi- mum reduction of 83.4%. In a multitasking environment, the same UDFS+PDVS technique given by the processor manufacturer. A volt- age level for each frequency is set such that even

Dick, Robert

239

Three-Dimensional Imaging of Hepatic Sinusoids in Mice Using Synchrotron Radiation Micro-Computed Tomography  

PubMed Central

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

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

2013-01-01

240

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

241

Sinusoidal calibration technique for Large Binocular Telescope system  

NASA Astrophysics Data System (ADS)

Telescopes of 8 meter class, like Large Binocular Telescope (LBT), are based on the concept of Deformable Secondary Mirror (DSM); in order to calculate the best DSM shape that correct the measured aberrations we need to calibrate the AO system, so we need a correlation between the DSM and the wave front sensor (WFS), i.e. we need the Interaction Matrix (IM). Usually we obtain the IM in laboratory or at the telescope using as source a reference fiber that illuminates both the deformable mirror and wave front sensor. But in case of LBT and all large telescopes, this technique can be very difficult or sometimes impossible, and calibration may be required to be performed on sky. So we need new calibration techniques, and we investigate about sinusoidal modulation one for LBT case. In the Arcetri solar tower (inside Arcetri Observatory) we recreated a set up environment similar to the telescope, and thanks to that we can test the calibration system in the same condition of the LBT. In preparation for the test some simulations of this sinusoidal modulation technique were needed, in order to choose the best parameters that increased SNR and reduced integration time. The paper will detail the simulation results of the calibration LBT system made with this new technique, and these results will be used to drive our tests in the tower.

Pieralli, F.; Puglisi, A.; Quiros Pacheco, F.; Esposito, S.

2008-07-01

242

Liver Sinusoidal Endothelial Cells Link Hyperinsulinemia to Hepatic Insulin Resistance  

PubMed Central

Insulin signaling in vascular endothelial cells (ECs) is critical to maintain endothelial function but also to mediate insulin action on peripheral glucose disposal. However, gene knockout studies have reached disparate conclusions. Thus, insulin receptor inactivation in ECs does not impair insulin action, whereas inactivation of Irs2 does. Previously, we have shown that endothelial ablation of the three Foxo genes protects mice from atherosclerosis. Interestingly, here we show that mice lacking FoxO isoforms in ECs develop hepatic insulin resistance through excessive generation of nitric oxide (NO) that impairs insulin action in hepatocytes via tyrosine nitration of insulin receptors. Coculture experiments demonstrate that NO produced in liver sinusoidal ECs impairs insulin’s ability to suppress glucose production in hepatocytes. The effects of liver sinusoidal ECs can be mimicked by NO donors and can be reversed by NO inhibitors in vivo and ex vivo. The findings are consistent with a model in which excessive, rather than reduced, insulin signaling in ECs predisposes to systemic insulin resistance, prompting a reevaluation of current approaches to insulin sensitization. PMID:23349480

Tsuchiya, Kyoichiro; Accili, Domenico

2013-01-01

243

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

NASA Technical Reports Server (NTRS)

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

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

1991-01-01

244

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

NASA Technical Reports Server (NTRS)

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

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

1994-01-01

245

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

246

Contrast constancy revisited: The perceived contrast of sinusoidal gratings above threshold.  

PubMed

The contrast sensitivity function of the human visual system, measured with sinusoidal luminance gratings, has an inverted U shape with a peak around 2-4?c/deg. Above threshold, it is thought that luminance gratings of equal physical contrasts but of distinguishably different spatial frequencies are all perceived as having similar contrasts, a phenomenon that has been termed contrast constancy. However, when suprathreshold contrast matches were measured for pairs of luminance gratings whose spatial frequencies were indistinguishable, the matching curves were not flat and followed a similar inverted U shape form as the contrast sensitivity function at threshold. It was therefore suggested that contrast constancy may only be revealed when matching the contrasts of clearly distinguishable spatial frequencies. Here, observers matched the perceived contrasts of suprathreshold luminance gratings of similar but visibly different spatial frequencies between 0.25 and 16?c/deg. The results show that, much like the contrast sensitivity function at threshold, observers are more sensitive to intermediate spatial frequencies (1-6?c/deg) than they are to either higher or to lower spatial frequencies. This tuning is evident when matching reference contrasts of 30-80%, implying a significant role in everyday vision. To demonstrate that these results were not due to local adaptation, the experiment was repeated with shorter stimulus duration, producing the same results. The extent of departure from contrast constancy found in the present study is compared to previously reported suprathreshold measurements. The results are also discussed with consideration to limitations with display apparatus such as monitor blur. PMID:25026464

Smith, Wayne S

2015-02-01

247

Voltage-dependent capacitance of human embryonic kidney cells.  

PubMed

We determine membrane capacitance, C as a function of dc voltage for the human embryonic kidney (HEK) cell. C was calculated from the admittance, Y, obtained during a voltage ramp when the HEK cell was held in whole-cell patch-clamp configuration. Y was determined at frequencies of 390.625 and from the measured current, i obtained with a dual-sinusoidal stimulus. We find that the fractional increase in the capacitance, C is small ( < 1%) and grows with the square of the voltage, Psi. C can be described by: C=C(0)(1+alpha(Psi+psi(s))2)[where C(0): Capacitance at 0 volts, psi(s): Difference in surface potential between cytoplasmic and extracellular leaflets and alpha: Proportionality constant]. We find that alpha and psi(s) are 0.120 (+/- 0.01) V(-2) and -0.073 (+/-0.017 V in solutions that contain ion channel blockers and 0.108 (+/- 0.29) V(-2) and -0.023 (+/- 0.009) V when 10 mM sodium salicylate was added to the extracellular solution. This suggests that salicylate does not affect the rate at which C grows with Psi, but reduces the charge asymmetry of the membrane. We also observe an additional linear differential capacitance of about (-46 fFV(-1)) in about 60% of the cells, this additional component acts simultaneously with the quadratic component and was not observed when salicylate was added to the solution. We suggest that the voltage dependent capacitance originates from electromechanical coupling either by electrostriction and/or Maxwell stress effects and estimate that a small electromechanical force (approximately equal to 1 pN) acts at physiological potentials. These results are relevant to understand the electromechanical coupling in outer hair cells (OHCs) of the mammalian cochlea, where an asymmetric bell-shaped C versus Psi relationship is observed upon application of a similar field. Prestin, a membrane protein expressed in OHCs is required to observe this function. When we compare the total charge contributions from HEK cell membrane (7 x 10(4) electrons, 10 pF cell) with that determined for prestin transfected cells (up to 5 x 10(6) electrons) we conclude that the charge contributions from the collective motion of membrane proteins and lipids in the field is dwarfed relative to that when prestin is present. We suggest that the capacitance-voltage relationships should be similar to that observed for HEK cells for OHCs that do not express prestin in their membranes. PMID:16711859

Farrell, Brenda; Do Shope, Cythnia; Brownell, William E

2006-04-01

248

Allosteric Voltage Gating of Potassium Channels II  

PubMed Central

Large-conductance Ca2+-activated K+ channels can be activated by membrane voltage in the absence of Ca2+ binding, indicating that these channels contain an intrinsic voltage sensor. The properties of this voltage sensor and its relationship to channel activation were examined by studying gating charge movement from mSlo Ca2+-activated K+ channels in the virtual absence of Ca2+ (<1 nM). Charge movement was measured in response to voltage steps or sinusoidal voltage commands. The charge–voltage relationship (Q–V) is shallower and shifted to more negative voltages than the voltage-dependent open probability (G–V). Both ON and OFF gating currents evoked by brief (0.5-ms) voltage pulses appear to decay rapidly (?ON = 60 ?s at +200 mV, ?OFF = 16 ?s at ?80 mV). However, QOFF increases slowly with pulse duration, indicating that a large fraction of ON charge develops with a time course comparable to that of IK activation. The slow onset of this gating charge prevents its detection as a component of IgON, although it represents ?40% of the total charge moved at +140 mV. The decay of IgOFF is slowed after depolarizations that open mSlo channels. Yet, the majority of open channel charge relaxation is too rapid to be limited by channel closing. These results can be understood in terms of the allosteric voltage-gating scheme developed in the preceding paper (Horrigan, F.T., J. Cui, and R.W. Aldrich. 1999. J. Gen. Physiol. 114:277–304). The model contains five open (O) and five closed (C) states arranged in parallel, and the kinetic and steady-state properties of mSlo gating currents exhibit multiple components associated with C–C, O–O, and C–O transitions. PMID:10436004

Horrigan, Frank T.; Aldrich, Richard W.

1999-01-01

249

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

250

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

251

Development of nanocrystalline Mn-Zn ferrites for high frequency transformer applications  

NASA Astrophysics Data System (ADS)

Microwave-Hydrothermal (M-H) method has been successfully used for the synthesis of nanocrystalline Mn-Zn ferrites which are used for high-frequency applications. As synthesized powders were characterized using X-ray diffraction (XRD) and transmission electron microscopy (TEM). The nanopowders were annealed at 600 °C/20 min using the microwave sintering method. The frequency dependence of dielectric constant ( ?') was measured in the range of 10 Hz-1.3 GHz and initial permeability ( ?i) was measured in the range of 10 Hz-1 MHz. The total power loss ( Pt) was measured on the annealed samples at 100 kHz and 200 mT condition. Conductor-embedded-ferrite transformers were fabricated and output power ( Po), efficiency ( ?) and temperature rise (? T) were measured at sinusoidal voltage of 25 V at 1 MHz. The transformer efficiency ( ?) was found to be high and surface rise of temperature (? T) is very low.

Praveena, K.; Sadhana, K.; Bharadwaj, S.; Murthy, S. R.

2009-08-01

252

Mach-Zehnder interferometry with periodic voltage pulses  

NASA Astrophysics Data System (ADS)

We investigate theoretically a Mach-Zehnder interferometer driven by a time-dependent voltage. Motivated by recent experiments, we focus on a train of Lorentzian voltage pulses which we compare to a sinusoidal and a constant voltage. We discuss the visibilities of Aharonov-Bohm oscillations in the current and in the noise. For the current, we find a strikingly different behavior in the driven as compared to the static case for voltage pulses containing multiple charges. For pulses containing fractional charges, we find a universality at path-length differences equal to multiples of the spacing between the voltage pulses. These observations can be explained by the electronic energy distribution of the driven contact. In the noise oscillations, we find additional features which are characteristic to time-dependent transport. Finite electronic temperatures are found to have a qualitatively different influence on the current and the noise.

Hofer, Patrick P.; Flindt, Christian

2014-12-01

253

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

254

DISPLAY OF PIXEL LOSS AND REPLICATION IN REPROJECTING RASTER DATA FROM THE SINUSOIDAL PROJECTION  

EPA Science Inventory

Recent studies show the sinusoidal projection to be a superior planar projection for representing global raster datasets. This study uses the sinusoidal projection as a basis for evaluating pixel loss and replication in eight other planar map projections. The percent of pixels ...

255

Novel Sum-of-Sinusoids Simulation Models for Rayleigh and Rician Fading Channels  

Microsoft Academic Search

The statistical properties of Clarke's fading model with a finite number of sinusoids are analyzed, and an improved reference model is proposed for the simulation of Rayleigh fading channels. A novel statistical simulation model for Rician fading channels is examined. The new Rician fading simulation model employs a zero-mean stochastic sinusoid as the specular (line-of- sight) component, in contrast to

Chengshan Xiao; Yahong Rosa Zheng; Norman C. Beaulieu

2006-01-01

256

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

Microsoft Academic Search

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

Hasmukh S. Patel; Richard G. Hoft

1974-01-01

257

Method of barrier voltages in cyclic accelerators  

NASA Astrophysics Data System (ADS)

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

Meshkov, I. N.

2014-03-01

258

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

259

Postural adjustments upon arm movement during sinusoidal induced body oscillations.  

PubMed

Postural adjustments due to the fast forward right arm elevation, performed during sinusoidal induced body oscillations in the phase of platform-induced dorsal, as well as plantar flexion of the foot were studied. Start times of the changes in the cyclic way of the center-of-gravity position (SG) and right ankle goniogram (GG) as well as the EMG onsets of the right soleus (S), anterior tibial (AT) and femoral biceps (FB) muscles relative to the ipsilateral anterior deltoid muscle (AD) EMG onset were measured. The EMG onset of FB muscle was found to occur significantly before the EMG onset of the AD muscle during plantar flexion series, wherever during dorsal flexion series the EMG onset of the AT muscle was significantly before the AD muscle EMG onset. Only the FB muscle changed significantly its EMG onset with the change of platform direction and started later in the dorsal flexion series. The results showed that two different strategies of postural adjustments might be distinguished depending on the direction of the platform movement. PMID:1815468

Gatev, P; Tankov, N; Gantchev, G; Krizkova, M

1991-01-01

260

Spontaneous immortalization of mouse liver sinusoidal endothelial cells.  

PubMed

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

2015-03-01

261

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

262

Electro-Optical High-Voltage Sensors  

NASA Technical Reports Server (NTRS)

Electro-optical sensors for measuring high voltages developed for use in automatically controlled power-distribution systems. Sensors connected to optoelectronic interrogating equipment by optical fibers. Because sensitive material and optical fibers are all dielectric, no problem in electrically isolating interrogating circuitry from high voltage, and no need for voltage dividers. Sensor signals transmitted along fibers immune to electromagnetic noise at radio and lower frequencies.

Gottsche, Allan; Johnston, Alan R.

1992-01-01

263

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

264

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

265

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

266

[Walking efficiency of blind people on trapezoidal and sinusoidal section tactile leading indicators].  

PubMed

Gait of visually impaired subjects (VIS) is worse than that of sighted ones. VIS can use tactile ground surface indicators to optimize their walking efficiency. Aim of the study was to compare VIS walking efficiency on either trapezoidal and sinusoidal shape leading indicators. VIS walking on the sinusoidal leading indicators showed a worsening of the time-distance parameters (a longer stance phase, a shorter swing phase and shorter step and stride lengths), reduced lower limb joint excursions and increased center of mass oscillations. In conclusion sinusoidal tactile indicators induce a stiffening of joints and a loss of balance with an increased risk of fall. PMID:23393839

Ranavolo, A; Conte, C; Iavicoli, S; Silvetti, A; Serrao, M; Sandrini, G; Pierelli, F; Draicchio, F

2011-01-01

267

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

268

A Study in Vibration Control: the Unknown Plant { Known Frequency Case  

Microsoft Academic Search

The paper presents a new approach to rejection of sinusoidal disturbances acting at the output of a discrete-time complex-valued linear stable plant with unknown dynamics. It is assumed that frequency of the sinusoidal disturbance is known, and that the output signal is contaminated with wideband measure- ment noise. It is not assumed that a reference signal, correlated with the disturbance,

Maciej Niedzwiecki; Michal Meller

269

Lipids promote survival, proliferation, and maintenance of differentiation of rat liver sinusoidal endothelial cells in vitro  

E-print Network

Primary rat liver sinusoidal endothelial cells (LSEC) are difficult to maintain in a differentiated state in culture for scientific studies or technological applications. Relatively little is known about molecular regulatory ...

Hang, Ta-Chun

270

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

271

Use of equivalent Hermitian Hamiltonian for PT-symmetric sinusoidal optical lattices  

NASA Astrophysics Data System (ADS)

We show how the beam dynamics of non-Hermitian PT-symmetric sinusoidal optical lattices can be approached from the point of view of the equivalent Hermitian problem, obtained by an analytic continuation in the transverse spatial variable x. In this latter problem the eigenvalue equation reduces to the Mathieu equation, whose eigenfunctions and properties have been well studied. That being the case, the beam propagation, which parallels the time-development of the wave-function in quantum mechanics, can be calculated using the equivalent of the method of stationary states. We also discuss a model potential that interpolates between a sinusoidal and periodic square well potential, showing that some of the striking properties of the sinusoidal potential, in particular birefringence, become much less prominent as one goes away from the sinusoidal case.

Jones, H. F.

2011-08-01

272

Design of error-compensating algorithms for sinusoidal phase shifting interferometry  

SciTech Connect

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

Groot, Peter de

2009-12-10

273

Walking strategies of visually impaired people on trapezoidal- and sinusoidal-section tactile groundsurface indicators.  

PubMed

The visual system in walking serves to perceive feedback or feed-forward signals. Therefore, visually impaired persons (VIP) have biased motor control mechanisms. The use of leading indicators (LIs) and long canes helps to improve their walking efficiency. The aims of this study were to compare the walking efficiency of VIP on trapezoidal- and sinusoidal-section LIs using an optoelectronic motion analysis system. VIP displayed a significantly longer stance phase, a shorter swing phase and shorter step and stride lengths when they walked on the sinusoidal LI than when they walked on the trapezoidal LI. Compared with the trapezoidal LI, VIP walking on the sinusoidal LI displayed significantly lower joint ranges of motion. The centre of mass lateral displacement was wider for VIP walking on the sinusoidal LI than on the trapezoidal LI. Some significant differences were also found in sighted persons walking on both LIs. In conclusion, the trapezoidal shape enabled visually impaired subjects to walk more efficiently, whereas the sinusoidal shape caused dynamic balance problems. STATEMENT OF RELEVANCE: These findings suggest that VIP can walk more efficiently, with a lower risk of falls, on trapezoidal-section than on sinusoidal-section LIs. These results should be considered when choosing the most appropriate ground tactile surface indicators for widespread use. PMID:21390954

Ranavolo, A; Conte, C; Iavicoli, S; Serrao, M; Silvetti, A; Sandrini, G; Pierelli, F; Draicchio, F

2011-03-01

274

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

275

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

SciTech Connect

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

Li Jinhuan; Sasaki, Osami

2011-07-10

276

Accurate Estimation of Common Sinusoidal Parameters in Multiple Channels  

E-print Network

which are common among all channels. By exploiting linear prediction and weighted least squares. Among all channels, there are some cisoids whose damping factors and frequencies are common, which cor parameters are estimated. This problem is more challenging than that of [12] where all poles are common among

So, Hing-Cheung

277

Write E and B fields as sinusoidal functions of  

E-print Network

is a traveling wave of E and B fields All waves travel through free space with same speed #12;EM Waves Spectrum #12;AM radio 100-1000 meters FM radio 1-10 meters TV channels 0.1-10 meters EM Waves Spectrum #12 rods of antenna with angular frequency Changing E and B fields form EM wave that travels away from

Bertulani, Carlos A. - Department of Physics and Astronomy, Texas A&M University

278

Proton transport under external applied voltage.  

PubMed

Proton transport through an electrolyte layer between platinum electrodes under a range of applied voltages is explored using reactive molecular dynamics simulation. The proton transport process is decomposed into vehicular and Grotthuss hopping components, and the two mechanisms and their correlation are investigated as a function of applied voltage. At higher applied voltages, the effect of the hopping mechanism is much larger as compared with the vehicular mechanism. As the voltage is increased, the net correlation between the two mechanisms goes from negative to positive, and both the hopping frequency as well as the number of consecutive forward hops increases. This behavior results in a larger total diffusion constant at higher values of the voltage. The behavior of the hydrated excess proton is therefore substantially different under an applied external voltage than in the normal bulk water environment. PMID:24720738

Cao, Zhen; Kumar, Revati; Peng, Yuxing; Voth, Gregory A

2014-07-17

279

Automatic voltage regulator using an AC voltage-voltage converter  

Microsoft Academic Search

Voltage sags and extended undervoltages are one of the main concerns of industry today. These voltage sags could cause high negative impact on productivity, which is certainly an undesirable aspect in industrial and commercial applications. Current tap-changing transformers used in distribution systems have proven to be inadequate in solving these problems related to line regulation. A solution to these problems

Steven M. Hietpas; Mark Naden

2000-01-01

280

Automatic voltage regulator using an AC voltage-voltage converter  

Microsoft Academic Search

Voltage sags and extended undervoltages are one of the main concerns of industries today. These voltage sags could cause high negative impact on productivity, which is certainly an undesirable aspect in industrial and commercial applications. Current tap-changing transformers used in distribution systems have proven to be inadequate in solving these problems related to line regulation. A solution to these problems

Steven M. Hietpas; Mark Naden

1999-01-01

281

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

282

VEGFR1-Positive Macrophages Facilitate Liver Repair and Sinusoidal Reconstruction after Hepatic Ischemia/Reperfusion Injury  

PubMed Central

Liver repair after acute liver injury is characterized by hepatocyte proliferation, removal of necrotic tissue, and restoration of hepatocellular and hepatic microvascular architecture. Macrophage recruitment is essential for liver tissue repair and recovery from injury; however, the underlying mechanisms are unclear. Signaling through vascular endothelial growth factor receptor 1 (VEGFR1) is suggested to play a role in macrophage migration and angiogenesis. The aim of the present study was to examine the role of VEGFR1 in liver repair and sinusoidal reconstruction after hepatic ischemia/reperfusion (I/R). VEGFR1 tyrosine kinase knockout mice (VEGFR1 TK-/- mice) and wild-type (WT) mice were subjected to hepatic warm I/R, and the processes of liver repair and sinusoidal reconstruction were examined. Compared with WT mice, VEGFR1 TK-/- mice exhibited delayed liver repair after hepatic I/R. VEGFR1-expressing macrophages recruited to the injured liver showed reduced expression of epidermal growth factor (EGF). VEGFR1 TK-/- mice also showed evidence of sustained sinusoidal functional and structural damage, and reduced expression of pro-angiogenic factors. Treatment of VEGFR1 TK-/- mice with EGF attenuated hepatoceullar and sinusoidal injury during hepatic I/R. VEGFR1 TK-/- bone marrow (BM) chimeric mice showed impaired liver repair and sinusoidal reconstruction, and reduced recruitment of VEGFR1-expressing macrophages to the injured liver. VEGFR1-macrophages recruited to the liver during hepatic I/R contribute to liver repair and sinusoidal reconstruction. VEGFR1 activation is a potential therapeutic strategy for promoting liver repair and sinusoidal restoration after acute liver injury. PMID:25162491

Ohkubo, Hirotoki; Ito, Yoshiya; Minamino, Tsutomu; Eshima, Koji; Kojo, Ken; Okizaki, Shin-ichiro; Hirata, Mitsuhiro; Shibuya, Masabumi; Watanabe, Masahiko; Majima, Masataka

2014-01-01

283

Application of the Josephson effect to voltage metrology  

Microsoft Academic Search

The unique ability of a Josephson junction to control the flow of magnetic flux quanta leads to a perfect relationship between frequency and voltage. Over the last 30 years, metrology laboratories have used this effect to greatly improve the accuracy of dc voltage standards. More recent research is focused on combining the ideas of digital signal processing with quantum voltage

SAMUEL P. BENZ; CLARK A. HAMILTON

2004-01-01

284

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

285

A DSP based multi-frequency 3D electrical impedance tomography system.  

PubMed

This paper describes the design of a multi-frequency Electrical impedance tomography (EIT) system, which provides a flexible mechanism for addressing up to 48 electrodes for imaging conductivity and permittivity distributions. A waveform generator based on a digital signal processor is used to produce sinusoidal waveforms with the ability to select frequencies in the range of 0.1-125 kHz. A software based phase-sensitive demodulation technique is used to extract amplitudes and phases from the raw measurements. Signal averaging and automatic gain control are also implemented in voltage and phase measurements. System performance was validated using a Cardiff-Cole Phantom and a saline filled cylindrical tank. The signal-to-noise ratio (SNR) using saline tank was greater than 60 dB and the maximum reciprocity error less than 4% for most frequencies. The common-mode rejection ratio (CMRR) was nearly 60 dB at 50 kHz. Image reconstruction performance was assessed using data acquired through a range of frequencies. This EIT system offers image reconstruction of both conductivity and permittivity distributions in three dimensions. The imaging results are presented in time difference and frequency difference imaging. PMID:18629646

Goharian, Mehran; Soleimani, Manuchehr; Jegatheesan, Aravinthan; Chin, Kenrick; Moran, Gerald R

2008-09-01

286

Vortex structures for flow over a delta wing with sinusoidal leading edge  

NASA Astrophysics Data System (ADS)

The idea of using sinusoidal leading edge as a kind of passive flow control method was inspired by observing the flipper movement of the humpback whale. It was believed that the protuberances along the whale's pectoral fin could delay stall, thus would enhance the maneuverability of the whale. It has also been shown that when equipped with sinusoidal leading edges, the stall of a delta wing could be delayed. In this paper, stereoscopic particle image velocimetry was adopted to study the vortex structures for the flow over a 52° swept delta wing with sinusoidal leading edges. A direct comparison with the flow over a baseline delta wing was made to illustrate the different vortex structures of these two kinds of models. Results have shown that the flow over the baseline delta wing was dominated by dual leading-edge vortices (LEVs), a structure that only existed for flow over nonslender delta wing at certain Reynolds number. On the other hand, the flow over the one with sinusoidal leading edge showed a very different pattern. It has been found in this paper that there were several pairs of LEVs existed on the leeward side of the wing, which might explain the stall-delaying effect of the delta wing with sinusoidal leading edges.

Chen, Huang; Wang, Jin-Jun

2014-06-01

287

Resolution of liver fibrosis requires myeloid cell-driven sinusoidal angiogenesis.  

PubMed

Angiogenesis is a key feature of liver fibrosis. Although, sinusoidal remodeling is believed to contribute to fibrogenesis, the impact of sinusoidal angiogenesis on the resolution of liver fibrosis remains undefined. Myeloid cells, particularly macrophages constantly infiltrate the fibrotic liver and can profoundly contribute to remodeling of liver sinusoids. We observe that the development of fibrosis is associated with decreased hepatic Vascular Endothelial Growth Factor (VEGF) expression as well as sinusoidal rarefication of the fibrotic scar. In contrast, the resolution of fibrosis is characterized by a rise in hepatic VEGF levels and revascularization of the fibrotic tissue. Genetic ablation of VEGF in myeloid cells or pharmacological inhibition of VEGF receptor 2 signaling prevents this angiogenic response and the resolution of liver fibrosis. We observe increased expression of Matrix Metalloproteases as well as decreased expression of Tissue inhibitor of metalloproteases confined to sinusoidal endothelial cells in response to myeloid cell VEGF. Remarkably, reintroduction of myeloid cell-derived VEGF upon recovery restores collagenolytic acitivity and the resolution of fibrosis. We identify myeloid cell-derived VEGF as a critical regulator extracellular matrix degradation by liver endothelial cells, thereby unmasking an unanticipated link between angiogenesis and the resolution of fibrosis. This article is protected by copyright. All rights reserved. PMID:25475053

Kantari-Mimoun, Chahrazade; Castells, Magali; Klose, Ralph; Meinecke, Anna-Katharina; Lemberger, Ursula J; Rautou, Pierre-Emmanuel; Pinot-Roussel, Hélène; Badoual, Cécile; Schrödter, Katrin; Osterreicher, Christoph H; Fandrey, Joachim; Stockmann, Christian

2014-12-01

288

A projector-camera setup for geometry-invariant frequency demultiplexing  

E-print Network

Consider a projector-camera setup where a sinusoidal pattern is projected onto the scene, and an image of the objects imprinted with the pattern is captured by the camera. In this configuration, the local frequency of the ...

Raskar, Ramesh

289

30 CFR 75.832 - Frequency of examinations; recordkeeping.  

Code of Federal Regulations, 2010 CFR

...STANDARDS-UNDERGROUND COAL MINES Underground High-Voltage Distribution High-Voltage Longwalls § 75.832 Frequency of examinations...7 days, a qualified person must examine each high-voltage continuous mining machine to verify...

2010-07-01

290

Employing Symmetry Constraints for Improved Frequency Estimation  

E-print Network

useful results. Keywords: Prony's method; Pisarenko's harmonic decomposition; sinusoid sig- nals; complex between prescribed energy levels in atoms are discrete. The frequency decomposition of a tone produced by the human voice or a musical instrument is discrete because only finitely many "modes" of vibration

Smyth, Gordon K.

291

Output voltage regulation in matrix converter fed power electronic transformer for power systems application in electric ship  

Microsoft Academic Search

The system described in this paper uses three matrix converters and a high frequency transformer to achieve isolation and voltage transformation from primary to secondary side. Two matrix converters produce high frequency voltage across a transformer, with open ended primary. A third matrix converter converts the high frequency chopped voltage to line frequency. The non-idealities such as leakage inductance of

Shabari Nath; K. K. Mohapatra; Ned Mohan

2009-01-01

292

The control unit of a single phase voltage regulator  

Microsoft Academic Search

Supplying regulated voltage to critical loads is an important topic for several years. This paper presents a single-phase electronic voltage regulator based on high frequency switching of an isolated transformer where primary side voltage is controlled by two full-bridge converters sharing a common DC bus and operating at 50 Hz and 20 kHz switching frequencies. This allows 50 Hz induced

Ilknur Colak; Deniz Yildirim

2010-01-01

293

Ultra-precision machining of sinusoidal surfaces using the cylindrical coordinate method  

NASA Astrophysics Data System (ADS)

Micro- and ultra-precision machining is an effective approach to achieving a nanometric surface finish, which is important for the sinusoidal surface as the calibrator of multi-axis precision machines. A cylindrical coordinate micromachining method is studied for the ultra-precision cutting of sinusoidal surfaces in this paper. The three-axis (X, Z, C) turning machine is used, whose NC path is generated in a spiral curve considering the workpiece surface and tool geometry. The avoiding interference technique is proposed, including the optimal selection of tool geometry and simulation of the cutting process. The tool geometry is optimized by using a sectional curve method. The cutting simulation is implemented using a constrained B-spline path fitting and a pipe model of the cutting face. With the method developed, sinusoidal surfaces with a nanometric finish of 5.54 nm in Ra are achieved effectively.

Zhang, X. D.; Fang, F. Z.; Wang, H. B.; Wei, G. S.; Hu, X. T.

2009-05-01

294

Self-renewing osteoprogenitors in bone marrow sinusoids can organize a hematopoietic microenvironment.  

PubMed

The identity of cells that establish the hematopoietic microenvironment (HME) in human bone marrow (BM), and of clonogenic skeletal progenitors found in BM stroma, has long remained elusive. We show that MCAM/CD146-expressing, subendothelial cells in human BM stroma are capable of transferring, upon transplantation, the HME to heterotopic sites, coincident with the establishment of identical subendothelial cells within a miniature bone organ. Establishment of subendothelial stromal cells in developing heterotopic BM in vivo occurs via specific, dynamic interactions with developing sinusoids. Subendothelial stromal cells residing on the sinusoidal wall are major producers of Angiopoietin-1 (a pivotal molecule of the HSC "niche" involved in vascular remodeling). Our data reveal the functional relationships between establishment of the HME in vivo, establishment of skeletal progenitors in BM sinusoids, and angiogenesis. PMID:17956733

Sacchetti, Benedetto; Funari, Alessia; Michienzi, Stefano; Di Cesare, Silvia; Piersanti, Stefania; Saggio, Isabella; Tagliafico, Enrico; Ferrari, Stefano; Robey, Pamela Gehron; Riminucci, Mara; Bianco, Paolo

2007-10-19

295

Three-Phase Sinusoidal Rectifier Consisting of Three Thyristors and a Resonant Switch  

NASA Astrophysics Data System (ADS)

Three-phase sinusoidal rectifier consisting of three thyristors and a resonant switch is presented. The switching transition of resonant switch is mainly governed by a series resonance and this allows the thyristors to turn on and off under the zero-current switching condition. Also, the currents flowing through power devices are always limited to the dc current. The experimental prototype employing three inverter-grade thyristors and two insulated-gate bipolar transistors is implemented to investigate the operation. The results confirm that the sinusoidal input currents with a near-unity power factor can be obtained under the pulse-width modulation.

Itoh, Ryozo; Ishizaka, Kouichi

296

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...

297

Substation voltage upgrading  

SciTech Connect

This report addresses specific issues to support sound yet not unduly conservative uprating practices for substations. The main parts of the report cover the insulation withstand and overvoltage protection aspects, environmental measurements, reliability criteria, and industry experience. First the insulation design concerns are addressed. Substation stress by a backflashover of the line insulation due to lightning in the vicinity of the substation is recognized as a critical stress. A representative part of a 550 kV BIL substation was erected at the EPRI High Voltage Transmission Research Center, where also a special test circuit was assembled to produce a fast front, slow tail (0.2/200 {mu}s) wave. The substation as well as some special configurations were tested for line-to-ground and line-to-line withstand. Computer studies were performed to complement the test results. A number of important conclusions was reached. The most prominent result in that the high frequency oscillations, as caused by reflections within the substation, do not effect the Critical Flashover Voltage (CFO). The present practice, based on the highest peak is therefore very conservative. The slow tail of the wave appears to dictate the CFO. An arrester model for computer studies to represent very fast as well as slow phenomena was derived. It is based on full scale arrester test data, made available in this project. The computer program to calculate arrester model parameters is also a part of the report. The electric environmental measurements are reported for the tested substation at the HVTRC and for the uprated substation of Public Service Company of Colorado, both before and after the uprating. The performance is satisfactory when corona free hardware is used. Insulation design criteria are analyzed based on substation reliability, the system viewpoint and consequences of the failure. Utility experience with uprated substations is reviewed.

Panek, J.; Elahi, H.; Lux, A.; Imece, A.F. (General Electric Co., Schenectady, NY (United States). Power Systems Engineering Dept.); LaPanse, R.A.; Stewart, J.R. (Public Service Co. of Colorado, Denver, CO (United States))

1992-04-01

298

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.

2009-12-08

299

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

300

Multi-frequency EIT and TAS Hardware Development  

Microsoft Academic Search

We present the development of a multi-frequency EIT (electrical impedance tomography) and TAS (trans- admittance scanner) system. Both systems share a common main platform based on a DSP and wireless serial RF connection to a PC. A digital waveform generator is used in both EIT and TAS producing sinusoidal waveforms with a chosen set of frequencies in the range of

J. K. Seo

301

Effects of temporal frequency on speed discrimination and perceived speed  

Microsoft Academic Search

We examined the effects of temporal frequency of moving stimuli on speed discrimination and perceived speed in human vision, using psychophysical methods. A speed-comparing paradigm displaying two drifting sinusoidal luminance gratings simultaneously was adopted in our experiments. In experimental 1, human vision was found to be most sensitive to the speeds of moving gratings with temporal frequency of about 12

H. Shen; Y. Shimodaira; G. Ohashi

2003-01-01

302

Mixed voltage VLSI design  

NASA Technical Reports Server (NTRS)

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

Panwar, Ramesh; Rennels, David; Alkalaj, Leon

1993-01-01

303

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

304

Robustness Analysis of the Matched Filter Detector Through Utilizing Sinusoidal Wave Sampling  

E-print Network

. 2. We set our detector to a constant nominal theta ?0 based on prior knowledge. 3. We specify a value to the probability of false alarm constraint ?. 4. We obtain our samples from a sinusoidal signal with unknown amplitude A. 15 B. Sampling of a...

Stedehouder, Jeroen

2010-01-16

305

A gain scheduled controller for sinusoidal ripple elimination of AC PM motor systems  

Microsoft Academic Search

An adaptive control algorithm for the elimination of torque and velocity ripples in the alternating current (AC) permanent magnet (PM) motor control systems is presented in this paper. A model of AC PM motor system includes n sinusoidal disturbances is first developed. The internal model principle (IMP) is then applied to design a controller to eliminate the torque and velocity

J. Wang; L. Qiu

2007-01-01

306

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

E-print Network

This work presents the direct torque control (DTC) techniques, implemented in four- and six-switch inverter, for brushless dc (BLDC) motors with non-sinusoidal back- EMF using two and three-phase conduction modes. First of all, the classical direct...

Ozturk, Salih Baris

2009-05-15

307

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

308

The controlled formation of ordered, sinusoidal structures by plasma oxidation of an elastomeric polymer  

E-print Network

. This process involves: i heating the PDMS to cause it to expand; ii exposing it to an oxygen plasma to generateThe controlled formation of ordered, sinusoidal structures by plasma oxidation of an elastomeric polymer Ned Bowden, Wilhelm T. S. Huck, Kateri E. Paul, and George M. Whitesidesa) Department of Chemistry

Prentiss, Mara

309

Band structure and optical properties of sinusoidal superlattices: ZnSe1-xTex  

NASA Astrophysics Data System (ADS)

This paper examines the band structure and optical selection rules in superlattices with a sinusoidal potential profile. The analysis is motivated by the recent successful fabrication of high quality ZnSe1-xTex superlattices in which the composition x varies sinusoidally along the growth direction. Although the band alignment in the ZnSe1-xTex sinusoidal superlattices is staggered (type II), they exhibit unexpectedly strong photoluminescence, thus suggesting interesting optical behavior. The band structure of such sinusoidal superlattices is formulated in terms of the nearly-free-electron (NFE) approximation, in which the superlattice potential is treated as a perturbation. The resulting band structure is unique, characterized by a single minigap separating two wide, free-electron-like subbands for both electrons and holes. Interband selection rules are derived for optical transitions involving conduction and valence-band states at the superlattice Brillouin-zone center, and at the zone edge. A number of transitions are predicted due to wave-function mixing of different subband states. It should be noted that the zone-center and zone-edge transitions are especially easy to distinguish in these superlattices because of the large width of the respective subbands. The results of the NFE approximation are shown to hold surprisingly well over a wide range of parameters, particularly when the period of the superlattice is short.

Yang, G.; Lee, S.; Furdyna, J. K.

2000-04-01

310

Jeremy McGibbon Page 1 Vertically Vibrated Ball-Chains in a Sinusoidal Potential  

E-print Network

Jeremy McGibbon Page 1 Vertically Vibrated Ball-Chains in a Sinusoidal Potential Jeremy McGibbon Introduction Ordinary ball-chains are seen to exhibit interesting coupled motions when vibrated on a vertically of the chain were taken from directly above by a Nikon D70S camera at 2-3 second intervals. Python code

Morris, Stephen W.

311

Diffraction Theory of Sinusoidal Gratings and Application to In Situ Surface Self-Diffusion Measurements  

Microsoft Academic Search

Computer calculations of the diffracted intensities from a sinusoidal surface grating have been carried out using analytical methods developed independently by Brekhovskikh, Senior, Stroke, and Petit from the electromagnetic theory of diffraction. These calculations provide a theoretical foundation for the newly developed laser-diffraction technique for continuously monitoring surface self-diffusion of solids under ultrahigh vacuum conditions. The calculated patterns were characterized

H. P. Bonzel; N. A. Gjostein

1968-01-01

312

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...

313

[The use of sinusoidal modulated currents as a method of electrosleep].  

PubMed

The study in 100 patients with stage II essential hypertension showed the validity of introduction of sinusoidal modulated currents into the technique of electric sleep. The results obtained served the basis for creation of the optimal therapeutic regime associated with a 94% response marked in hypertensive patients subjected to correction of systemic and cerebral hemodynamics. PMID:2629233

Danilova, I N; Orekhova, E M

1989-01-01

314

Voltage monitoring system  

NASA Technical Reports Server (NTRS)

A description is given of a system for monitoring the voltage at a remote location and determining when the voltage exceeds upper and lower levels. The system includes transmission lines for transmitting the voltage back to a central station and applying such to an amplifier having a pair of outputs. One of the outputs of the amplifier is applied to an oscillograph. The other output is fed through an isolation transformer, a full wave rectifier, to a pair of unijunctional transistor circuits for producing pulses when the voltage exceeds or drops below a predetermined level. These pulses, in turn, energize a relay which turns on the oscillograph for recording the voltages being monitored.

Canicatti, C. L. (inventor)

1975-01-01

315

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

316

Age and Individual Differences in Controlled Force Exertion Measured by a Computer-Generated Sinusoidal and Quasi-Random Display  

ERIC Educational Resources Information Center

This study examined age group and individual differences in controlled force exertion by emulating sinusoidal and quasi-random waveforms in 222 right-handed female adults aged 20 to 86 years. The subjects matched their submaximal grip strength by the dominant hand to changing demand values displayed as either a sinusoidal or a quasi-random…

Nagasawa, Yoshinori; Demura, Shinichi

2010-01-01

317

Reliability study of micromechanical actuators for electrostatic RMS voltage measurements using bulk-silicon technology  

Microsoft Academic Search

Micro-electromechanical sensors have been developed for high-frequency voltage metrology applications. They should ultimately allow RF to DC voltage transfer. The conventional measurement principle is based on RF power dissipation by ohmic resistances allowing RMS voltage conversion by the square power law. The principle of electrostatic force, which has already been demonstrated to work from DC to gigahertz frequencies, is a

Jan Dittmer; Rolf Judaschke; Stephanus Büttgenbach

2009-01-01

318

Adaptive optimization of a lead compensator based upon input command frequency during operations of X-Y positioning table  

E-print Network

based on the specifications from the DSF. As a demonstration, a supervisory controller is developed for an X-Y positioning table which tracks a frequency varying sinusoid. The results show that this control scheme allows costs normally only considered...

Jordan, Eric Alan

2012-06-07

319

High voltage RF feedthrough bushing  

DOEpatents

Described is a multi-element, high voltage radio frequency bushing for trmitting RF energy to an antenna located in a vacuum container. The bushing includes a center conductor of complex geometrical shape, an outer coaxial shield conductor, and a thin-walled hollow truncated cone insulator disposed between central and outer conductors. The shape of the center conductor, which includes a reverse curvature portion formed of a radially inwardly directed shoulder and a convex portion, controls the uniformity of the axial surface gradient on the insulator cone. The outer shield has a first substantially cylindrical portion and a second radially inwardly extending truncated cone portion.

Grotz, Glenn F. (Huntington Station, NY)

1984-01-01

320

Soft-Switched Single-Phase Voltage-Doubler Rectifier Using Pump Circuits  

NASA Astrophysics Data System (ADS)

Soft-switched single-phase voltage-doubler rectifier using pump circuits is presented. The active power devices in the full-bridge resonant switch are allowed to turn on and off under zero-current switching (ZCS) and zero-voltage switching (ZVS) conditions, respectively. The switching transition is mainly governed by a series resonance. The experimental prototype employing two dual-switch power modules with insulated-gate bipolar transistors is implemented to investigate the operation under the pulse-width modulation. The experimental results confirm that the input current can be waveshaped sinusoidally with a near-unity power factor.

Itoh, Ryozo; Ishizaka, Kouichi

321

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

322

Neural network controlled voltage disturbance detector and output voltage regulator for Dynamic Voltage Restorer  

Microsoft Academic Search

This paper describes the high power DVR (Dynamic Voltage Restorer) with the neural network controlled voltage disturbance detector and output voltage regulator. Two essential parts of DVR control are how to detect the voltage disturbance such as voltage sag and how to compensate it as fast as possible respectively. The new voltage disturbance detector was implemented by using the delta

Y. H. Chung; H. J. Kim; G. H. Kwon; T. B. Park; S. H. Kim; K. S. Kim; J. W. Choe

2007-01-01

323

A low-noise bandgap voltage reference employing dynamic element matching  

E-print Network

Bandgap voltages references are widely used in IC design, but are sensitive to low-frequency noise and component mismatch. This thesis describes the design and testing of a new IC voltage reference that targets these issues ...

Herbst, Steven (Steven G.)

2011-01-01

324

Semaphorin 3E secreted by damaged hepatocytes regulates the sinusoidal regeneration and liver fibrosis during liver regeneration.  

PubMed

The liver has a remarkable capacity to regenerate after injury. Although the regulatory mechanisms of hepatocytic regeneration have been a subject of intense study, the dynamism of the sinusoids, specialized blood vessels in the liver, remains largely unknown. Transient activation of hepatic stellate cells and hepatic sinusoidal endothelial cells, which constitute the sinusoids, contributes to liver regeneration during acute injury, whereas their sustained activation causes liver fibrosis during chronic injury. We focused on understanding the association between damaged hepatocytes and sinusoidal regeneration or liver fibrogenesis using a carbon tetrachloride-induced liver injury mouse model. Damaged hepatocytes rapidly expressed semaphorin 3E (Sema3e), which induced contraction of sinusoidal endothelial cells and thereby contributed to activating hepatic stellate cells for wound healing. In addition, ectopic and consecutive expression of Sema3e in hepatocytes by the hydrodynamic tail-vein injection method resulted in disorganized regeneration of sinusoids and sustained activation of hepatic stellate cells. In contrast, liver fibrosis ameliorated in Sema3e-knockout mice compared with wild-type mice in a chronic liver injury model. Our results indicate that Sema3e, secreted by damaged hepatocytes, affects sinusoidal regeneration in a paracrine manner during liver regeneration, suggesting that Sema3e is a novel therapeutic target in liver fibrogenesis. PMID:24930441

Yagai, Tomoki; Miyajima, Atsushi; Tanaka, Minoru

2014-08-01

325

Sinusoidal and cycloidal F-type spin structures in multiferroic orthomanganites  

NASA Astrophysics Data System (ADS)

We performed resonant x-ray scattering on F-type (0 q 0) reflections of TbMnO3 and Eu0.75Y0.25MnO3 at Mn L-edge, where modulation q are near 0.28 and 0.25, respectively. By using circularly and linearly polarized light, we could confirm that F-type spin structure in TbMnO3 is c- axis sinusoid above ferroelectric TC and bc-plane cycloid below TC, while F-type spin structure in Eu0.75Y0.25MnO3 is not cycloid but c-axis sinusoid down to base temperature. F-type spin structures in multiferroic orthomanganites can be explained as canted spin moment developed by Dzyaloshinskii-Moriya interaction and are also consistent in symmetric analysis.

Jang, Hoyoung; Lee, J.-S.; Ko, K.-T.; Noh, W.-S.; Koo, T. Y.; Kim, J.-Y.; Lee, K.-B.; Park, J.-H.; Zhang, C. L.; Kim, Sung Baek; Cheong, S.-W.

2010-03-01

326

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

2014-10-01

327

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

328

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

329

Linear Optical Encoder System With Sinusoidal Signal Distortion Below - 60 dB  

Microsoft Academic Search

This paper describes a high-precision linear optical scanner, combining an averaged optical sensor array with appropriate 10-??m graduated scales on a measurement-fixed plate and a Vernier sliced parallel scale on a reading plate, where the total distortion of the generated quadrature sinusoidal signals below -60 dB was achieved by distributing and mismatching optical edges over a number of sine-wave periods

Jernej Rozman; Anton Pletersek

2010-01-01

330

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

331

Sinusoidal rotatory chair system by an auto-tuning fuzzy PID controller  

SciTech Connect

This paper presents DC servo motor speed control characteristics by fuzzy logic controller and considers position following control response with controller. A sinusoidal rotatory chair system using an auto tuning fuzzy PID control was designed to evaluate the vestibular function. Then the system is investigated for the effects of change by the fuzziness of fuzzy variable. If this system is supported by a channel, it is considered for application in industry of multi joint robot and precision parallel driving.

Park, H.A. [Kwangju Health Inst. of Science (Korea, Republic of). Dept. of Computer and Information Processing; Cha, I.S. [Dong Shin Univ., Chonnam (Korea, Republic of). Dept. of Electrical and Electronic Engineering; Baek, H.L. [Cho Sun Univ., Kwangju (Korea, Republic of). Dept. of Electrical Engineering

1995-12-31

332

Cervico-ocular responses (COR) during slow sinusoidal head movements in subjects with bilateral labyrinthine lesions  

Microsoft Academic Search

Eye movements in five patients with chronic bilateral labyrinthine loss were tested with sinusoidal movements during cervico-ocular stimulation and active head movements (0.05, 0.1 and 0.2 s-1; 20, 40, and 60°) and were compared with healthy subjects. Consideration was given to saccadic activity and slow phase velocity of nystagmus and overall gaze shift. The cervico-ocular response was not altered in

H. C. Leopold; M. Doerr; U. Thoden

1983-01-01

333

Building Sinusoids  

ERIC Educational Resources Information Center

In this article, the author describes the development and implementation of a measurement-based group activity designed to support students in understanding the connection between angle magnitude and the shape of the sine function. She explains that the benefit of this activity is that it allows students to build their trigonometric knowledge…

Landers, Mara G.

2013-01-01

334

Operating stability of a self-breakdown spark-gap frequency switch rated at a voltage of 300 kV and a switched power of up to 450 J  

NASA Astrophysics Data System (ADS)

A test bench for studying two-electrode spark gaps rated at a voltage of 300 kV and a pulse repetition rate of up to 10 Hz and operating in air at elevated pressure. The typical time of pulse charging of a capacitive storage in the bench equals about 100 ?s. The object of investigation is a spark gap the operating stability of which at a level of 10% of the rate voltage is achieved by initiating a corona discharge at the prebreakdown stage. It is shown that unstable operation is due to the accumulation of nitrogen oxides in the gap. To maintain the oxide content at an acceptable level, continuous gas purging is applied and necessary gas flow rates are estimated.

Koval'chuk, B. M.; Korolev, Yu. D.; Kumpyak, E. V.; Frants, O. B.; Shemyakin, I. A.

2014-12-01

335

Bidirectional power electronic transformer based compact dynamic voltage restorer  

Microsoft Academic Search

In this paper a dynamic voltage restorer (DVR) circuit with a bi-directional power electronic transformer (PET) structure is proposed to correct input utility voltage distortions on a sensitive load. This DVR-PET contains full-bridge DC-link inverter (FBDCI), high frequency isolating transformer (HFIT), cyclo-converter and output filter. A phase shift modulation (PSM) control scheme is used to regulate compensation voltage. The proper

S. H. Hosseini; M. B. B. Sharifian; M. Sabahi; A. Y. Goharrizi; G. B. Gharehpetian

2009-01-01

336

Voltage correction power flow  

SciTech Connect

A method for power flow solution of weakly meshed distribution and transmission networks is presented. It is based on oriented ordering of network elements. That allows an efficient construction of the loop impedance matrix and rational organization of the processes such as: power summation (backward sweep), current summation (backward sweep) and node voltage calculation (forward sweep). The first step of the algorithm is calculation of node voltages on the radial part of the network. The second step is calculation of the breakpoint currents. Then, the procedure continues with the first step, which is preceded by voltage correction. It is illustrated that using voltage correction approach, the iterative process of weakly meshed network voltage calculation is faster and more reliable.

Rajicic, D.; Ackovski, R.; Taleski, R. (Univ. Sv. Kiril i Metodij'', Skopje, Macedonia (Greece). Dept. of Electrical Engineering)

1994-04-01

337

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

338

Advanced High Power DC-DC Converter using A Novel Type Voltage Source Full-Bridge Soft-Switching PWM Inverter with High Frequency Transformer Link for Arc Welding Applications  

NASA Astrophysics Data System (ADS)

This paper presents a new circuit topology of full-bridge soft-switching PWM inverter linked DC-DC power converter composed of conventional full-bridge high frequency PWM inverter with high frequency transformer and an active quasi-resonant snubber consisting of an additional power switching device in series with DC busline and a lossless capacitor in parallel with DC busline. Under this proposed high frequency soft-switching PWM inverter linked DC-DC converter, four power switches in the full-bridge arms and DC busline series switch can achieve ZVS at turn-off commutation. By developing the advanced soft-switching PWM high frequency inverter type DC-DC converter, although the conduction power loss of DC busline series power switch increases a little, the total turn-off switching loss of full-bridge high frequency inverter power modules can be sufficiently lowered more and more in the higher frequency range of 60kHz. As a result, when the switching frequency of high frequency inverter power stage using IGBT power modules is designed so as to be more than about 10kHz, the more the switching frequency of inverter increases, the more this high frequency soft-switching DC-DC converter has remarkable advantage as for the power conversion efficiency as compared with the conventional hard-switching PWM inverter DC-DC converter. Its practical effectiveness of high power density and high performance is actually proved for TIG arc welding equipment in industry.

Morimoto, Keiki; Doi, Toshimitsu; Manabe, Haruhiko; Ahmed, Tarek; Hiraki, Eiji; Lee, Hyun-Woo; Nakaoka, Mutsuo

339

Chaotic dynamics of a frequency-modulated microwave oscillator with time-delayed feedback.  

PubMed

We present a chaotic frequency-modulated microwave source that is governed by a simple, first-order nonlinear delay differential equation. When a sinusoidal nonlinearity is incorporated, the dynamical behaviors range from fixed-point to periodic to chaotic, depending on the feedback strength. When the sinusoidal nonlinearity is replaced by a binary nonlinearity, the system exhibits a complex periodic attractor with no fixed-point solution. PMID:23556938

Dao, Hien; Rodgers, John C; Murphy, Thomas E

2013-03-01

340

SONIC — Self-optimizing narrowband interference canceler: Comparison of two frequency tracking strategies  

Microsoft Academic Search

This paper presents a new approach to rejection of complex-valued sinusoidal disturbances acting at the output of a discrete-time linear stable plant with unknown and possibly time-varying dynamics. It is assumed that both the instantaneous frequency of the sinusoidal disturbance and its amplitude may be slowly varying with time and that the output signal is contaminated with wideband measurement noise.

Maciej Niedzwiecki; Michal Meller

2010-01-01

341

Streamer inception in mineral oil under ac voltage  

Microsoft Academic Search

This paper describes an experimental study of streamer inception in mineral oil under ac voltage, with rod and point electrodes. Positive and negative streamer inception frequencies versus voltage are investigated in gaps up to 40 cm with different electrode shapes and different conditioning of the oil (filtered oil, addition of cellulose particles, water). Streamer inception probability increases exponentially versus field,

O. Lesaint; T. V. Top

2011-01-01

342

Low-Voltage Magnetron Application for Microwave Cooking  

Microsoft Academic Search

System requirements for domestic electronic ovens are outlined with emphasis on low cost and long life. A low-voltage magnetron permits operation from a voltage doubler supply, thus avoiding use of an expensive plate transformer. Magnetron design factors include frequency, power, and tolerance to a wide range of load impedance. A complete RF generator is described which meets the desired specifications.

James E. Staats

1968-01-01

343

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

344

Circuit engineering for transformerless converters of feed-voltage level  

Microsoft Academic Search

The design principle is presented for transformerless voltage converters with automatic setting of the optimal frequency of voltage conversion. It is noted that the proposed circuit-engineering technology is compatible with integrated-circuit fabrication techniques and provides for a high efficiency. The possible use of such devices in aircraft power supply systems is noted.

A. E. Goriunov

1985-01-01

345

An improved vaseline gap voltage clamp for skeletal muscle fibers  

Microsoft Academic Search

A Vaseline gap potentiometric recording and voltage clamp method is developed for frog skeletal muscle fibers. The method is based on the Franken- haeuser-Dodge voltage clamp for myelinated nerve with modifications to improve the frequency response, to compensate for external series resistance, and to com- pensate for the complex impedance of the current-passing pathway. Fragments of single muscle fibers are

BERTIL HILLE; DONALD T. CAMPBELL

1976-01-01

346

High resolution fiber-optic voltage sensors based on the electrostrictive effect  

Microsoft Academic Search

We demonstrate high resolution fiber-optic dc and ac voltage sensors based on the electrostrictive effect in PMN based relaxor ferroelectrics. The quadratic relationship between the applied voltage and the induced strain in electrostrictive ceramics allows mixing of a signal at frequency ? with a carrier at a much higher frequency ?, thereby upconverting the information of interest to a frequency

Larry Fabiny; Sandeep T. Vohra; Frank Bucholtz

1994-01-01

347

Stability issues in IC Low Drop Out voltage regulators  

E-print Network

Performance issues of IC Low Drop Out (LDO) voltage regulators, with specific reference to stability, are discussed in this thesis. Evaluation of existing frequency compensation schemes and their performances across operating loads is presented...

Chava, Krishna Chaitanya

2012-06-07

348

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

349

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

350

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

351

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

352

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

353

Voltage balanced multilevel voltage source converter system  

DOEpatents

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

354

High-frequency ac power distribution in Space Station  

NASA Technical Reports Server (NTRS)

A utility-type 20-kHz ac power distribution system for the Space Station, employing resonant power-conversion techniques, is presented. The system converts raw dc voltage from photovoltaic cells or three-phase LF ac voltage from a solar dynamic generator into a regulated 20-kHz ac voltage for distribution among various loads. The results of EASY5 computer simulations of the local and global performance show that the system has fast response and good transient behavior. The ac bus voltage is effectively regulated using the phase-control scheme, which is demonstrated with both line and load variations. The feasibility of paralleling the driver-module outputs is illustrated with the driver modules synchronized and sharing a common feedback loop. An HF sinusoidal ac voltage is generated in the three-phase ac input case, when the driver modules are phased 120 deg away from one another and their outputs are connected in series.

Tsai, Fu-Sheng; Lee, Fred C. Y.

1990-01-01

355

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.

356

Structural and functional aspects of the liver and liver sinusoidal cells in relation to colon carcinoma metastasis  

PubMed Central

Nowadays, liver metastasis remains difficult to cure. When tumor cells escape and arrive in the liver sinusoids, they encounter the local defense mechanism specific to the liver. The sinusoidal cells have been widely described in physiologic conditions and in relation to metastasis during the past 30 years. This paper provides an “overview” of how these cells function in health and in diseases such as liver metastasis. PMID:16127736

Vekemans, Katrien; Braet, Filip

2005-01-01

357

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

358

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

359

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

360

Imaging voltage in neurons  

PubMed Central

In the last decades, imaging membrane potential has become a fruitful approach to study neural circuits, especially in invertebrate preparations with large, resilient neurons. At the same time, particularly in mammalian preparations, voltage imaging methods suffer from poor signal to noise and secondary side effects, and they fall short of providing single-cell resolution when imaging of the activity of neuronal populations. As an introduction to these techniques, we briefly review different voltage imaging methods (including organic fluorophores, SHG chromophores, genetic indicators, hybrid, nanoparticles and intrinsic approaches), and illustrate some of their applications to neuronal biophysics and mammalian circuit analysis. We discuss their mechanisms of voltage sensitivity, from reorientation, electrochromic or electro-optical phenomena, to interaction among chromophores or membrane scattering, and highlight their advantages and shortcomings, commenting on the outlook for development of novel voltage imaging methods. PMID:21220095

Peterka, Darcy S.; Takahashi, Hiroto; Yuste, Rafael

2011-01-01

361

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

362

Phase controlled dc-ac converter with high frequency switching  

NASA Astrophysics Data System (ADS)

A sinusoidal dc-ac converter is presented in which a pair of switches is placed on each side of the primary and secondary of the isolation transformer. This converter is controlled by the phase difference between the two pairs of switches. The transformer is miniaturized by making the switching frequency high. This converter is especially suitable for small uninterruptible power supply systems.

Harada, Koosuke; Sakamoto, Hiroshi; Shoyama, Masahito

363

Unified constant-frequency integration control of active power filters  

Microsoft Academic Search

An active power filter (APF) is a device that is connected in parallel to and cancels the reactive and harmonic currents from a group of nonlinear loads so that the resulting total current drawn from the AC mains is sinusoidal. This paper presents a unified constant-frequency integration (UCI) APF control method based on one-cycle control. This method employs an integrator

Luowei Zhou; Keyue M. Smedley

2000-01-01

364

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

365

Low-voltage gyrotrons  

NASA Astrophysics Data System (ADS)

For a long time, the gyrotrons were primarily developed for electron cyclotron heating and current drive of plasmas in controlled fusion reactors where a multi-megawatt, quasi-continuous millimeter-wave power is required. In addition to this important application, there are other applications (and their number increases with time) which do not require a very high power level, but such issues as the ability to operate at low voltages and have compact devices are very important. For example, gyrotrons are of interest for a dynamic nuclear polarization, which improves the sensitivity of the nuclear magnetic resonance spectroscopy. In this paper, some issues important for operation of gyrotrons driven by low-voltage electron beams are analyzed. An emphasis is made on the efficiency of low-voltage gyrotron operation at the fundamental and higher cyclotron harmonics. These efficiencies calculated with the account for ohmic losses were, first, determined in the framework of the generalized gyrotron theory based on the cold-cavity approximation. Then, more accurate, self-consistent calculations for the fundamental and second harmonic low-voltage sub-THz gyrotron designs were carried out. Results of these calculations are presented and discussed. It is shown that operation of the fundamental and second harmonic gyrotrons with noticeable efficiencies is possible even at voltages as low as 5-10 kV. Even the third harmonic gyrotrons can operate at voltages about 15 kV, albeit with rather low efficiency (1%-2% in the submillimeter wavelength region).

Glyavin, M. Yu.; Zavolskiy, N. A.; Sedov, A. S.; Nusinovich, G. S.

2013-03-01

366

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

367

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

368

Pathogenesis of FOLFOX induced sinusoidal obstruction syndrome in a murine chemotherapy model  

PubMed Central

Background & Aims Sinusoidal obstruction syndrome (SOS) following oxaliplatin based chemotherapy can have a significant impact on post-operative outcome following resection of colorectal liver metastases. To date no relevant experimental models of oxaliplatin induced SOS have been described. The aim of this project was to establish a rodent model which could be utilised to investigate mechanisms underlying SOS to aid the development of therapeutic strategies. Methods C57Bl/6 mice, maintained on a purified diet, were treated with intra-peritoneal FOLFOX (n = 10), or vehicle (n = 10), weekly for five weeks and culled one week following final treatment. Sections of the liver and spleen were fixed in formalin and paraffin embedded for histological analysis. The role of oxidative stress on experimental-induced SOS was determined by dietary supplementation with butylated hydroxyanisole and N-acetylcysteine. Results FOLFOX treatment was associated with the development of sinusoidal dilatation and hepatocyte atrophy on H&E stained sections of the liver in keeping with SOS. Immunohistochemistry for p21 demonstrated the presence of replicative senescence within the sinusoidal endothelium. FOLFOX induced endothelial damage leads to a pro-thrombotic state within the liver associated with upregulation of PAI-1 (p <0.001), vWF (p <0.01) and Factor X (p <0.001), which may contribute to the propagation of liver injury. Dietary supplementation with the antioxidant BHA prevented the development of significant SOS. Conclusions We have developed the first reproducible model of chemotherapy induced SOS that reflects the pathogenesis of this disease in patients. It appears that the use of antioxidants alongside oxaliplatin based chemotherapy may be of value in preventing the development of SOS in patients with colorectal liver metastases. PMID:23624001

Robinson, S.M.; Mann, J.; Vasilaki, A.; Mathers, J.; Burt, A.D.; Oakley, F.; White, S.A.; Mann, D.A.

2013-01-01

369

3D Hepatic Cultures Simultaneously Maintain Primary Hepatocyte and Liver Sinusoidal Endothelial Cell Phenotypes  

PubMed Central

Developing in vitro engineered hepatic tissues that exhibit stable phenotype is a major challenge in the field of hepatic tissue engineering. However, the rapid dedifferentiation of hepatic parenchymal (hepatocytes) and non-parenchymal (liver sinusoidal endothelial, LSEC) cell types when removed from their natural environment in vivo remains a major obstacle. The primary goal of this study was to demonstrate that hepatic cells cultured in layered architectures could preserve or potentially enhance liver-specific behavior of both cell types. Primary rat hepatocytes and rat LSECs (rLSECs) were cultured in a layered three-dimensional (3D) configuration. The cell layers were separated by a chitosan-hyaluronic acid polyelectrolyte multilayer (PEM), which served to mimic the Space of Disse. Hepatocytes and rLSECs exhibited several key phenotypic characteristics over a twelve day culture period. Immunostaining for the sinusoidal endothelial 1 antibody (SE-1) demonstrated that rLSECs cultured in the 3D hepatic model maintained this unique feature over twelve days. In contrast, rLSECs cultured in monolayers lost their phenotype within three days. The unique stratified structure of the 3D culture resulted in enhanced heterotypic cell-cell interactions, which led to improvements in hepatocyte functions. Albumin production increased three to six fold in the rLSEC-PEM-Hepatocyte cultures. Only rLSEC-PEM-Hepatocyte cultures exhibited increasing CYP1A1/2 and CYP3A activity. Well-defined bile canaliculi were observed only in the rLSEC-PEM-Hepatocyte cultures. Together, these data suggest that rLSEC-PEM-Hepatocyte cultures are highly suitable models to monitor the transformation of toxins in the liver and their transport out of this organ. In summary, these results indicate that the layered rLSEC-PEM-hepatocyte model, which recapitulates key features of hepatic sinusoids, is a potentially powerful medium for obtaining comprehensive knowledge on liver metabolism, detoxification and signaling pathways in vitro. PMID:21103392

Kim, Yeonhee; Rajagopalan, Padmavathy

2010-01-01

370

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

371

Scintillations associated with bottomside sinusoidal irregularities in the equatorial F region  

NASA Technical Reports Server (NTRS)

Multisatellite scintillation observations and spaced receiver drift measurements are presented for a category of equatorial F region plasma irregularities characterized by nearly sinusoidal waveforms in the ion number density. The observations were made at Huancayo, Peru, and the measurements at Ancon, Peru, associated with irregularities observed by the Atmospheric-Explorer-E satellite on a few nights in December 1979. Utilizing ray paths to various geostationary satellites, it was found that the irregularities grow and decay almost simultaneously in long-lived patches extending at least 1000 km in the east-west direction.

Basu, S.; Basu, S.; Valladares, C. E.; Dasgupta, A.; Whitney, H. E.

1986-01-01

372

Departures from Sinusoidal Variation in the Occurrence of Lightning in Equatorial Africa  

NASA Astrophysics Data System (ADS)

Lightning in many African countries has a well defined pattern of occurrence which is well described by a sinusoidal curve that peaks close to the summer solstice.(Collier et al. 2006). Interesting departures from this pattern occur in countries bordering the Gulf of Guinea and these can be explained by the annual migration of the inter-tropical convergence which greatly influences weather in that region. Detailed curves for the occurrence of lightning are given for all African countries derived from the LIS instrument on the TRMM spacecraft for seven years of observation.

Hughes, A. R.

2008-12-01

373

Wide-band coronagraph with sinusoidal phase in the angular direction.  

PubMed

We suggest a new phase mask coronagraph that can work in a wide band of wavelengths. The phase mask has alternatively sinusoidal and uniform functions in the angular direction. We compare it with the four-quadrant phase mask coronagraph and vortex phase mask coronagraph. Through numerical tests, we find that the new mask gives a deep extinction of star light and has a small inner working angle. It is also shown that this mask has a better performance in chromatism than the others for a wide band of wavelengths. PMID:22565717

Ma, Ourui; Cao, Qing; Hou, Fanzhen

2012-05-01

374

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

375

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

376

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

377

A fast ac voltage regulator  

Microsoft Academic Search

The study and implementation of an AC voltage regulator is presented in this paper. Traditionally an AC voltage regulator is made with a transformer tap changer or with an AC-AC converter based on buck topologies, recently the developments in ac-ac converter makes feasible the implementation of voltage regulator with other topologies. In this paper is analyzed an ac voltage regulator

N. Vazquez; A. Velazquez; C. Hernandez; E. Rodriguez; R. Orosco

2008-01-01

378

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

379

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

380

Scavenger receptor-mediated endocytosis by sinusoidal cells in rat bone marrow  

SciTech Connect

Endocytosis of serum albumin by sinusoidal endothelial cells in rat bone marrow was investigated initially at the ultrastructural level with subsequent biochemical investigation of the specificity mediating this event. Bovine serum albumin adsorbed to 20nm colloidal gold particles (AuBSA) was chosen as the electron microscopic probe. Morphological data strongly suggested that a receptor was involved in uptake of AuBSA. Confirmation of receptor involvement in the uptake of AuBSA by marrow sinusoidal endothelial cells was achieved utilizing an in situ isolated hind limb perfusion protocol in conjunction with unlabeled, radiolabeled, and radio-/colloidal gold labeled probes. The major findings of competition and saturation experiments were: (1) endocytosis of AuBSA was mediated by a receptor for modified/treated serum albumin; (2) endocytosis of formaldehyde-treated serum albumin was mediated by a binding site which may be the same or closely related to the site responsible for the uptake of AuBSA; and (3) endocytosis of native untreated albumin was not mediated by receptor and probably represents fluid-phase pinocitosis.

Geoffroy, J.S.

1987-01-01

381

A novel modular bioreactor to in vitro study the hepatic sinusoid.  

PubMed

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

382

Sinusoidal Endothelial Cell Repopulation Following Ischemia/Reperfusion Injury in Rat Liver Transplantation  

PubMed Central

We evaluated the kinetics by which rat liver sinusoidal endothelial cells (LSECs) are repopulated in the reperfused transplanted liver after 18 hours of cold ischemic storage. We found that the majority of LSECs in livers cold-stored for 18 hours in University of Wisconsin solution are seriously compromised and often are retracted before transplantation. Sinusoids rapidly re-endothelialize within 48 hours of transplantation, and repopulation is coincident with up-regulation of hepatocyte vascular endothelial growth factor expression and vascular endothelial growth factor receptor-2 expression on large vessel endothelial cells and repopulating LSECs. Although re-endothelialization occurs rapidly, we show here, using several high-resolution imaging techniques and 2 different rat liver transplantation models, that engraftment of bone marrow–derived cells into functioning LSECs is routinely between 1% and 5%. Conclusion Bone marrow plays a measurable but surprisingly limited role in the rapid repopulation and functional engraftment of bone marrow–derived LSECs after cold ischemia and warm reperfusion. PMID:17929236

Stolz, Donna Beer; Ross, Mark A.; Ikeda, Atsushi; Tomiyama, Koji; Kaizu, Takashi; Geller, David A.; Murase, Noriko

2007-01-01

383

Wetting of anisotropic sinusoidal surfaces—experimental and numerical study of directional spreading  

NASA Astrophysics Data System (ADS)

Directional wettability, i.e. the variation of wetting properties, depending on the surface orientation, can be achieved by anisotropic surface texturing. A new high-precision process can produce homogeneous sinusoidal surfaces (in particular, parallel grooves) at the microscale, with a nanoscale residual roughness five orders of magnitude smaller than the texture features. Static wetting experiments have shown that this pattern, even with a very small aspect ratio, can induce a strong variation of the contact angle, depending on the direction of the observation. A comparison with numerical simulations (using Surface Evolver software) shows good agreement and could be used to predict fluid–solid interaction and droplet behaviour on textured surfaces. Two primary mechanisms of directional spreading of water droplets on textured stainless steel surface have been identified. The first one is the mechanical barrier created by the textured surface peaks; this limits spreading in a perpendicular direction to the surface anisotropy. The second one is the capillary action inside of the sinusoidal grooves, which accelerates spreading along the grooves. Spreading has been shown to depend strongly on the history of wetting and internal drop dynamics.

Fischer, G.; Bigerelle, M.; Kubiak, K. J.; Mathia, T. G.; Khatir, Z.; Anselme, K.

2014-10-01

384

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

385

Modulation frequency and orientation tuning of second-order texture mechanisms  

E-print Network

Modulation frequency and orientation tuning of second-order texture mechanisms A. Serge Arsenault October 15, 1998 Modulation frequency and orientation tuning of second-order mechanisms underlying was modulated about an aver- age value of 4.7 cycles per degree (cpd) according to a sinusoidal function

Kingdom, Frederick A. A.

386

Chronicles from the Frequency Domain: Benefits & Applications of AC Thermal Modeling, Simulation & Measurement  

E-print Network

applicable to components that are typically operated in pulsed mode, such as power electronics by a sinusoidal power dissipation (with angular frequency = f ). The thermal fields can be mathematically.e. the ratio of the temperature and power phasor in the junction. Thermal frequency domain analysis is directly

387

A Design Procedure for Optimizing the LLC Resonant Converter as a Wide Output Range Voltage Source  

Microsoft Academic Search

LLC resonant converter is one of the most suitable circuit topologies that have been introduced for designing constant output voltage switched-mode power supplies. In this paper, a design procedure is introduced for using this converter as a wide output range voltage source. Unlike constant output voltage applications which need small converter inductance ratio and narrow switching frequency variations, for wide

Reza Beiranvand; Bizhan Rashidian; Mohammad Reza Zolghadri; Seyed Mohammad Hossein Alavi

2012-01-01

388

Charge Collection and Capacitance-Voltage analysis in irradiated n-type magnetic Czochralski silicon detectors  

E-print Network

Charge Collection and Capacitance-Voltage analysis in irradiated n-type magnetic Czochralski capacitance and from the amount of collected charge. Capacitance-voltage (C-V) measurements at different frequencies and temperatures are being compared with the bias voltage dependence of the charge collection

California at Santa Cruz, University of

389

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.

Mendel, Clifford W. (Albuquerque, NM); Savage, Mark E. (Albuquerque, NM)

1992-01-01

390

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

391

Voltage controlled current source  

DOEpatents

A seven decade, voltage controlled current source is described for use in testing intermediate range nuclear instruments that covers the entire test current range of from 10 picoamperes to 100 microamperes. High accuracy is obtained throughout the entire seven decades of output current with circuitry that includes a coordinated switching scheme responsive to the input signal from a hybrid computer to control the input voltage to an antilog amplifier, and to selectively connect a resistance to the antilog amplifier output to provide a continuous output current source as a function of a preset range of input voltage. An operator controlled switch provides current adjustment for operation in either a real-time simulation test mode or a time response test mode.

Casne, Gregory M. (Pittsburgh, PA)

1992-01-01

392

Large-signal characterizations of DDR IMPATT devices based on group III-V semiconductors at millimeter-wave and terahertz frequencies  

NASA Astrophysics Data System (ADS)

Large-signal (L-S) characterizations of double-drift region (DDR) impact avalanche transit time (IMPATT) devices based on group III-V semiconductors such as wurtzite (Wz) GaN, GaAs and InP have been carried out at both millimeter-wave (mm-wave) and terahertz (THz) frequency bands. A L-S simulation technique based on a non-sinusoidal voltage excitation (NSVE) model developed by the authors has been used to obtain the high frequency properties of the above mentioned devices. The effect of band-to-band tunneling on the L-S properties of the device at different mm-wave and THz frequencies are also investigated. Similar studies are also carried out for DDR IMPATTs based on the most popular semiconductor material, i.e. Si, for the sake of comparison. A comparative study of the devices based on conventional semiconductor materials (i.e. GaAs, InP and Si) with those based on Wz-GaN shows significantly better performance capabilities of the latter at both mm-wave and THz frequencies.

Acharyya, Aritra; Mallik, Aliva; Banerjee, Debopriya; Ganguli, Suman; Das, Arindam; Dasgupta, Sudeepto; Banerjee, J. P.

2014-08-01

393

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

394

Detection of Arcing in Low Voltage Distribution Systems  

Microsoft Academic Search

The paper proposes algorithms based on both frequency and time-frequency analysis for characterization of arcing in low voltage (230 V) distribution systems. A filter bank based approach has been suggested to identify arcing. The protection system aims at preventing fire-hazards resulting from such sustained arcing currents. Experiments have been designed to simulate contact arcing in the laboratory. The algorithms are

Asit K Mishra; Aurobinda Routray; Ashok K. Pradhan

2008-01-01

395

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

396

Spatial frequency doubling - Retinal or central. [visual illusion  

NASA Technical Reports Server (NTRS)

When a wide field is sinusoidally modulated both in space and in time, the spatial frequency of the pattern will appear doubled at high rates of modulation. Kelly (1966) proposed that this illusion is due to temporal integration of the nonlinear brightness response of the visual system. The anatomical locus of this temporal integrator is uncertain, and could be subcortical. Results indicate that spatial frequency doubling follows binocular disparity detection and is thus a cortical phenomenon.

Richards, W.; Felton, T. B.

1973-01-01

397

A wideband frequency synthesizer for built-in self testing of analog integrated circuits  

E-print Network

detector, low pass filter and a voltage controlled oscillator (VCO) shown in Figure 4. The phase detector senses any phase error between the reference frequency and the output frequency from the feedback. The phase detector produces an output voltage... proportional to the phase error. The error translated voltage is sent to the VCO through a low pass filter. The filter cleans the VCO control voltage by filtering out high frequency noise spurs and unwanted higher harmonics. The VCO frequency increases...

Yan, Wenjian

2004-11-15

398

AC Voltage Conversion Problems  

NSDL National Science Digital Library

This learning object, created by Terry L.M. Bartelt and John Rosz of Wisconsin Online Resource Center, focuses on AC voltage conversion problems. Aside from just the presentation, this site also contains practice problems. Overall, this is a useful presentation for a brief introduction on this topic.

Bartelt, Terry L. M.

399

Measuring Breakdown Voltage.  

ERIC Educational Resources Information Center

The article discusses an aspect of conductivity, one of the electrical properties subdivisions, and describes a tester that can be shop-built. Breakdown voltage of an insulation material is specifically examined. Test procedures, parts lists, diagrams, and test data form are included. (MF)

Auer, Herbert J.

1978-01-01

400

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

401

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

402

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

403

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

404

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

405

How membrane proteins sense voltage.  

PubMed

The ionic gradients across cell membranes generate a transmembrane voltage that regulates the function of numerous membrane proteins such as ion channels, transporters, pumps and enzymes. The mechanisms by which proteins sense voltage is diverse: ion channels have a conserved, positively charged transmembrane region that moves in response to changes in membrane potential, some G-protein coupled receptors possess a specific voltage-sensing motif and some membrane pumps and transporters use the ions that they transport across membranes to sense membrane voltage. Characterizing the general features of voltage sensors might lead to the discovery of further membrane proteins that are voltage regulated. PMID:18354422

Bezanilla, Francisco

2008-04-01

406

First-order energy-integral model for thin Newtonian liquids falling along sinusoidal furrows.  

PubMed

An average modeling methodology under the lubrication approach is used to formulate a set of three coupled nonlinear partial differential equations based on the Nusselt scales. This system, known as the energy-integral method in literature, simplifies the Navier-Stokes equation at the first order and analyzes the dynamics of a thin sheet of fluid flowing over a topography with sinusoidally varying longitudinal furrows. Limiting cases of the linear stability results are mathematically discussed and the complete linear system is numerically handled by means of finite differences to approximate the eigenfunctions and their derivatives in a periodic domain. In a geometry which resembles a vertical shift of a topography, with the amplitude being equal to the shift length, it is found that such a geometry stabilizes the flow compared to its counterpart with no shift, such that the wave characteristics get affected. To confirm the stability results, a numerical investigation is performed. PMID:22587182

Sadiq, I Mohammed Rizwan

2012-03-01

407

Dynamical Diffraction of Light from 1D Photonic Crystals with Sinusoidal Profile of Permittivity  

NASA Astrophysics Data System (ADS)

Bragg reflection and transmission spectra of the 1D photonic crystals characterized by a spatially sinusoidal profile of permittivity are studied as a function of the crystal-plate thickness. Applicability of the dynamical theory of diffraction in describing such spectra is considered. In the framework of the dynamical theory, we (i) calculated and analysed the reflection and transmission spectra for oblique incidence of polarized light, (ii) computed the spectra making use of the transfer matrix technique, and (iii) compared quantitatively the results of the two approaches. As a result, the analytical dynamical theory of diffraction is found to be correct in calculating the Bragg spectra in the vicinity of single photonic band-gap when the plate thickness is equal to the integer number of the spatial periods, or the permittivity is symmetric about the middle plane of the structure.

Romanenko, K. O.; Sel'kin, A. V.

2014-12-01

408

Single-shot calibration of soft x-ray mirrors using a sinusoidal transmission grating.  

PubMed

Calibration of soft x-ray diagnostics is a challenge due to the lack of laboratory-size calibrated sources. An in situ calibration method for newly developed x-ray mirrors, is presented. The x-ray source is produced by laser-matter interaction, and twin transmission gratings which create two identical dispersion lines. The gratings have a sinusoidal transmission function, which produces a highly precise high-orders free spectrum. An x-ray mirror interacts with one of the dispersion lines, and the mirror efficiency curve as a function of wavelength is extracted. Mirror efficiency shows good agreement with the literature, and evidence of water layer may justify the need of in situ calibration. PMID:25430374

Shpilman, Z; Ehrlich, Y; Maman, S; Levy, I; Shussman, T; Oren, G; Zakosky Nueberger, I; Hurvitz, G

2014-11-01

409

Mathieu function solutions for photoacoustic waves in sinusoidal one-dimensional structures  

NASA Astrophysics Data System (ADS)

The photoacoustic effect for a one-dimensional structure, the sound speed of which varies sinusoidally in space, is shown to be governed by an inhomogeneous Mathieu equation with the forcing term dependent on the spatial and temporal properties of the exciting optical radiation. New orthogonality relations, traveling wave Mathieu functions, and solutions to the inhomogeneous Mathieu equation are found, which are used to determine the character of photoacoustic waves in infinite and finite length phononic structures. Floquet solutions to the Mathieu equation give the positions of the band gaps, the damping of the acoustic waves within the band gaps, and the dispersion relation for photoacoustic waves. The solutions to the Mathieu equation give the photoacoustic response of the structure, show the space equivalent of subharmonic generation and acoustic confinement when waves are excited within band gaps.

Wu, Binbin; Diebold, Gerald J.

2012-07-01

410

Mathieu function solutions for photoacoustic waves in sinusoidal one-dimensional structures.  

PubMed

The photoacoustic effect for a one-dimensional structure, the sound speed of which varies sinusoidally in space, is shown to be governed by an inhomogeneous Mathieu equation with the forcing term dependent on the spatial and temporal properties of the exciting optical radiation. New orthogonality relations, traveling wave Mathieu functions, and solutions to the inhomogeneous Mathieu equation are found, which are used to determine the character of photoacoustic waves in infinite and finite length phononic structures. Floquet solutions to the Mathieu equation give the positions of the band gaps, the damping of the acoustic waves within the band gaps, and the dispersion relation for photoacoustic waves. The solutions to the Mathieu equation give the photoacoustic response of the structure, show the space equivalent of subharmonic generation and acoustic confinement when waves are excited within band gaps. PMID:23005556

Wu, Binbin; Diebold, Gerald J

2012-07-01

411

Tacrine sinusoidal uptake and biliary excretion in sandwich-cultured primary rat hepatocytes.  

PubMed

PURPOSE. The knowledge of hepatic disposition kinetics of tacrine, a first cholinesterase inhibitor was approved by FDA for the treatment of Alzheimer's disease (AD), would help to understand its hepatotoxicity, its therapeutic effect, and improve the management of patients with AD. The current study aims to characterize tacrine hepatic transport kinetics and study the role of organic cation transporters (OCTs), P-glycoprotein (P-gp) and multidrug resistance-associated protein (MRP2) in tacrine sinusoidal uptake and biliary excretion. METHODS. Modulation of tacrine hepatic uptake and efflux, biliary excretion index (BEI%), were performed in sandwich-cultured primary rat hepatocytes (SCHs) using transporters inhibitors. Conformation of the integrity of SCHs model was established by capturing images with light-contrast and fluorescence microscopy. RESULTS. Tacrine uptake in SCHs was carrier-mediated process and saturable with apparent Km of 31.5±9.6 µM and Vmax of 908±72 pmol/min/mg protein. Tetraethyl ammonium (TEA), cimetidine and verapamil significantly reduced tacrine uptake with more pronounced effect observed with verapamil which caused 3-fold reduction in tacrine uptake, indicating role for OCTs. Tacrine has a biliary excretion in SCHs with maximum BEI% value of 22.9±1.9% at 10 min of incubation. Addition of MK571 and valspodar decreased the BEI% of tacrine by 40 and 60% suggesting roles for canalicular MRP2 and P-gp, respectively. CONCLUSIONS. Our results show that in addition to metabolism, tacrine hepatic disposition is carrier-mediated process mediated by sinusoidal OCTs, and canalicular MRP2 and P-gp. PMID:25224352

Mohamed, Loqman A; Kaddoumi, Amal

2014-01-01

412

Overview of semi-sinusoidal stellar variability with the CoRoT satellite  

NASA Astrophysics Data System (ADS)

Context. To date, the CoRoT space mission has produced more than 124 471 light curves. Classifying these curves in terms of unambiguous variability behavior is mandatory for obtaining an unbiased statistical view on their controlling root-causes. Aims: The present study provides an overview of semi-sinusoidal light curves observed by the CoRoT exo-field CCDs. Methods: We selected a sample of 4206 light curves presenting well-defined semi-sinusoidal signatures. The variability periods were computed based on Lomb-Scargle periodograms, harmonic fits, and visual inspection. Results: Color-period diagrams for the present sample show the trend of an increase of the variability periods as long as the stars evolve. This evolutionary behavior is also noticed when comparing the period distribution in the Galactic center and anti-center directions. These aspects indicate a compatibility with stellar rotation, although more information is needed to confirm their root-causes. Considering this possibility, we identified a subset of three Sun-like candidates by their photometric period. Finally, the variability period versus color diagram behavior was found to be highly dependent on the reddening correction. The CoRoT space mission was developed and is operated by the French space agency CNES, with the participation of ESA's RSSD and Science Programmes, Austria, Belgium, Brazil, Germany, and Spain.Table 2 is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/555/A63

De Medeiros, J. R.; Ferreira Lopes, C. E.; Leão, I. C.; Canto Martins, B. L.; Catelan, M.; Baglin, A.; Vieira, S.; Bravo, J. P.; Cortés, C.; de Freitas, D. B.; Janot-Pacheco, E.; Maciel, S. C.; Melo, C. H. F.; Osorio, Y.; Porto de Mello, G. F.; Valio, A.

2013-07-01

413

A secure communication scheme based on chaotic Duffing oscillators and frequency estimation for the transmission of binary-coded messages  

NASA Astrophysics Data System (ADS)

This work presents a new technique to securely transmit and retrieve a message signal via chaotic systems. The main contribution of this paper is two-fold: the way that the message signal is encrypted in the frequency of a sinusoidal term and a novel frequency estimator for retrieving the message. In our system, a two-valued message signal modulates the frequency of the Duffing oscillator sinusoidal term. Then, two chaotic signals generated by the oscillator are encrypted with a Delta modulator and sent through a noisy channel. A Lyapunov-based observer is used in the receiver side to retrieve the sinusoidal term that contains the message and a novel frequency estimator is then used to retrieve the confidential message signal. The system was implemented in Matlab/Simulink in order to analyze its performance.

Zapateiro, Mauricio; Vidal, Yolanda; Acho, Leonardo

2014-04-01

414

Lossless equalization of frequency combs.  

PubMed

Frequency combs obtained by sinusoidal phase modulation of narrowband cw lasers are widely used in the field of optical communications. However, the resulting spectral envelope of the comb is not flat. We propose a general and efficient approach to achieve flat frequency combs with tunable bandwidth. The idea is based on a two-step process. First, efficient generation of a train with a temporal flat-top-pulse profile is required. Second, we use large parabolic phase modulation in every train period to map the temporal intensity shape into the spectral domain. In this way the resulting spectral envelope is flat, and the size is tunable with the chirping rate. Two different schemes are proposed and verified through numerical simulations. PMID:18709099

Torres-Company, Víctor; Lancis, Jesús; Andrés, Pedro

2008-08-15

415

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

416

Stable voltage reference sources  

Microsoft Academic Search

A family of well-regulated voltage references are shown, which are readily integrable for use with emitter-coupled logic, threshold logic, or linear circuit arrays. By relying on the relatively well-matched characteristics and the temperature tracking of integrated transistors and resistor ratios, the circuit can provide a large range of output fractions of the power supply. The relationships of the circuit components

D. Hampel

1972-01-01

417

High frequency RF discharge laser  

SciTech Connect

This patent describes a high frequency high power stabilized RF discharge laser comprising in combination; a ground plane; a stripline waveguide electrode having first and second ends located in a plane substantially parallel to the ground plane; an RF source connected to the first end of the stripline waveguide electrode by a means for preventing a high voltage pulse from damaging the RF source; a discharge tube located between the ground plane and the stripline waveguide electrode; preionization pulse means including a high voltage source applying a high voltage pulse to the second end of the stripline waveguide electrode. It also includes a means placed between the high voltage pulse source and the stripline waveguide electrode for preventing the RF from damaging the high voltage source; and a waveguide region formed by the ground plane and the stripline waveguide electrode wherein the discharge tube lies within the waveguide region.

Christensen, C.P.

1986-12-23

418

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

419

Quantum tomography of current and voltage states in nanoelectric circuits  

NASA Astrophysics Data System (ADS)

Nanoelectric circuit with small variable capacitance C(t) and inductance L(t) considered as quantum parametric oscillator with varying frequency is studied. Current and voltage in quantum circuits play the role of conjugate "position" and "momentum" of the parametric oscillator with the wave function (density matrix) depending on current (voltage). The physical realization of electric circuits with varying capacitance and inductance by Josephson junctions used in superconducting devices is discussed in the context of possibilities to use an analog of nonstationary Casimir effect to create current (voltage) in the circuits by varying the Josephson junction parameters. The idea to observe the analog of nonstationary Casimir effect proposed in [1]-[5] is accompanied by the possibility to introduce the tomographic probability description of the current and voltage state. The equation for optical and symplectic quantum tomograms of evolving current (voltage) states in nanoelectric circuits is obtained in explicit form.

Man'ko, O. V.

2012-03-01

420

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

421

Development of a fast voltage control method for electrostatic accelerators  

NASA Astrophysics Data System (ADS)

The concept of a novel fast voltage control loop for tandem electrostatic accelerators is described. This control loop utilises high-frequency components of the ion beam current intercepted by the image slits to generate a correction voltage that is applied to the first few gaps of the low- and high-energy acceleration tubes adjoining the high voltage terminal. New techniques for the direct measurement of the transfer function of an ultra-high impedance structure, such as an electrostatic accelerator, have been developed. For the first time, the transfer function for the fast feedback loop has been measured directly. Slow voltage variations are stabilised with common corona control loop and the relationship between transfer functions for the slow and new fast control loops required for optimum operation is discussed. The main source of terminal voltage instabilities, which are due to variation of the charging current caused by mechanical oscillations of charging chains, has been analysed.

Lobanov, Nikolai R.; Linardakis, Peter; Tsifakis, Dimitrios

2014-12-01

422

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

423

Automatic voltage-imbalance detector  

SciTech Connect

A device is described 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, R.E.; McCormick, J.B.; Kerwin, W.J.

1981-05-20

424

Electromechanical considerations in developing low-voltage RF MEMS switches  

Microsoft Academic Search

This paper reports on the design, fabrication, and testing of a low-actuation voltage Microelectromechanical systems (MEMS) switch for high-frequency applications. The mechanical design of low spring-constant folded-suspension beams is presented first, and switches using these beams are demonstrated with measured actuation voltages of as low as 6 V. Furthermore, common nonidealities such as residual in-plane and gradient stress, as well

Dimitrios Peroulis; Sergio P. Pacheco; Kamal Sarabandi; Linda P. B. Katehi

2003-01-01

425

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

426

Voltage-gated ion channels  

Microsoft Academic Search

Voltage-dependent ion channels are membrane proteins that conduct ions at high rates regulated by the voltage across the membrane. They play a fundamental role in the generation and propagation of the nerve impulse and in cell homeostasis. The voltage sensor is a region of the protein bearing charged amino acids that relocate upon changes in the membrane electric field. The

Francisco Bezanilla

2005-01-01

427

Chaotic Dynamics of Red Blood Cells in a Sinusoidal Shear Flow Jules Dupire1,2,3  

E-print Network

PRL, 2009 Chaotic Dynamics of Red Blood Cells in a Sinusoidal Shear Flow Jules Dupire1,2,3 , Manouk, 2010) We show that the motion of individual red blood cells in an oscillating moderate shear flow that the movement of a red blood cell (RBC) in a steady shear flow is well described by two ordinary equa- tions

Paris-Sud XI, Université de

428

ENGR 202 Electrical Fundamentals II Catalog Description: Sinusoidal steady-state analysis and phasors. Application of circuit  

E-print Network

: · Fundamentals of Electric Circuits, 5th Edition, C. K. Alexander and M. N. O. Sadiku, McGraw-Hill, 2013ENGR 202 ­ Electrical Fundamentals II Catalog Description: Sinusoidal steady-state analysis and phasors. Application of circuit analysis techniques to solve single-phase and three-phase circuits

429

Analytical Study of Optimal Layout of Permanent Magnets in IPMSM for Generating Sinusoidal Flux-Density Distribution in Air Gap  

NASA Astrophysics Data System (ADS)

This paper analytically demonstrates the optimal layout of permanent magnets for generating a sinusoidal flux density distribution in the air gap of the interior permanent-magnet synchronous machines with multiple flux barriers. In addition, practical design methods for realizing the optimal layout are proposed, and the designs are verified by conducting finite element analysis.

Kondo, Minoru

430

A Biologically Inspired Biped Locomotion Strategy for Humanoid Robots: Modulation of Sinusoidal Patterns by a Coupled Oscillator Model  

Microsoft Academic Search

Biological systems seem to have a simpler but more robust locomotion strategy than that of the existing biped walking controllers for humanoid robots. We show that a humanoid robot can step and walk using simple sinusoidal desired joint trajectories with their phase adjusted by a coupled oscillator model. We use the center-of-pressure location and velocity to detect the phase of

Jun Morimoto; Gen Endo; Jun Nakanishi; Gordon Cheng

2008-01-01

431

Unidirectional heat flux through the horizontal fluid layer with sinusoidal wall temperature at the top or bottom boundaries  

Microsoft Academic Search

Infinite horizontal fluid layer is considered between the top and bottom walls. Either top or bottom wall temperature is sinusoidally oscillated in terms of the constant average temperature in an opposing horizontal wall. This is the system with no temperature difference between the top and bottom walls in time-averaged sense, as studied by Kalabin et al. for a square channel.

Qiu-Wang Wang; Gang Wang; Min Zeng; Hiroyuki Ozoe

2008-01-01

432

Upward Heat Flux Through the Horizontal Fluid Layer of Water with Sinusoidal Wall Temperature at the Top or Bottom Boundary  

Microsoft Academic Search

Either top or bottom wall temperature of an infinite horizontal fluid layer at Pr = 6 is sinusoidally oscillated with constant average temperature on the opposing horizontal wall. This is a system with no temperature difference between the top and bottom walls in a time-averaged sense, as studied by Kalabin et al. for a square channel. The fluid is water, and the

Qiu-Wang Wang; Gang Wang; Min Zeng; Hiroyuki Ozoe

2007-01-01

433

Expandable multiterminal DC systems based on voltage droop  

SciTech Connect

This paper introduces a decentralized control scheme for the parallel connection of multiple rectifiers feeding a dc network with numerous inverters. The coordination of multiple HV dc systems without explicit communication is accomplished by the use of dc-side voltages as a droop mechanism. The dc side voltage serves the role of frequency in an ordinary ac system. The approach is most suitable to superconducting dc systems and to dc systems that span small distances and where voltage is relatively uniform throughout the dc system. This paper presents the concept in the context of a high capacity superconducting 10 KV urban infeed.

Johnson, B.K. (Univ. of Idaho, Moscow, ID (United States)); Lasseter, R.H.; Alvarado, F.L. (Univ. of Wisconsin, Madison, WI (United States)); Adapa, R. (Electric Power Research Inst., Palo Alto, CA (United States))

1993-10-01

434

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

435

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

436

Excitation of voltage oscillations in an induction voltage adder  

NASA Astrophysics Data System (ADS)

The induction voltage adder is an accelerator architecture used in recent designs of pulsed-power driven x-ray radiographic systems such as Sandia National Laboratories’ Radiographic Integrated Test Stand (RITS), the Atomic Weapons Establishment’s planned Hydrus Facility, and the Naval Research Laboratory’s Mercury. Each of these designs relies on magnetic insulation to prevent electron loss across the anode-cathode gap in the vicinity of the adder as well as in the coaxial transmission line. Particle-in-cell simulations of the RITS adder and transmission line show that, as magnetic insulation is being established during a pulse, some electron loss occurs across the gap. Sufficient delay in the cavity pulse timings provides an opportunity for high-momentum electrons to deeply penetrate the cavities of the adder cells where they can excite radio-frequency resonances. These oscillations may be amplified in subsequent gaps, resulting in oscillations in the output power. The specific modes supported by the RITS-6 accelerator and details of the mechanism by which they are excited are presented in this paper.

Bruner, Nichelle; Genoni, Thomas; Madrid, Elizabeth; Welch, Dale; Hahn, Kelly; Oliver, Bryan

2009-07-01

437

Comprehensive analysis of Barkhausen emission spectra using pulse height analysis, frequency spectrum, and pulse wave form analysis  

Microsoft Academic Search

The dependence of magnetic Barkhausen emissions (MBE) upon both field excitation and detection frequencies and excitation wave form was studied in order to investigate two of several crucial factors which affect the emissions. Sinusoidal, triangular, and square wave forms were used to generate the MBE and the pulse height spectra, frequency spectra, and pulse wave forms of these signals were

L. B. Sipahi; D. C. Jiles; D. Chandler

1993-01-01

438

FPGA Implementation of a Switching Frequency Modulation Circuit for EMI Reduction in Resonant Inverters for Induction Heating Appliances  

Microsoft Academic Search

This paper presents the use of frequency modulation as a spread spectrum technique to reduce conducted electromagnetic interference (EMI) in the A frequency band (9-150 kHz) caused by resonant inverters used in induction heating home appliances. For sinusoidal, triangular, and sawtooth modulation profiles, the influence of peak period deviation in EMI reduction and in the power delivered to the load

Luis A. Barragan; Denis Navarro; JesÚs Acero; Isidro Urriza; JosÉ M. Burdio

2008-01-01

439

Mini-Scale Power Distribution Network Feeding Trapezoidal-Wave Voltages to Power Electronic Loads with Diode Rectifiers  

NASA Astrophysics Data System (ADS)

This paper proposes a novel three-phase power distribution system feeding trapezoidal voltages to various power electronic loads with diode rectifier front-ends. The network distributes trapezoidal voltages generated by synchronous superposition of wave-shaping voltages onto sinusoidal voltages available from a utility power grid. The power distribution by the trapezoidal voltages allows reducing harmonics of the line currents without electronic switching devices because of a spontaneously widened conduction period of the current waveforms. The reduction of the harmonic currents also contributes to improve total power factor at the load input terminals and efficiency of the power transmission cables. Since the diodes of the rectifiers successively commutate the trapezoidal waves during periods of their flat parts, not only total harmonic distortion of the currents is improved, but also voltage ripple across the dc-buses of the rectifiers can effectively be reduced with less filter capacitors. In addition, the system offers an uninterruptible power supply function by immediately changing its outputs from the wave-shaping voltages to the trapezoidal voltages when interruption occurs in the power grid. In this paper, a prototype of the system is experimentally examined from various angles of operating characteristics and test results are presented to prove feasibility of the proposed system.

Noguchi, Toshihiko; Imoto, Masaru; Sato, Yoshikazu

440

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

441

Electronic Voltage and Current Transformers Testing Device  

PubMed Central

A method for testing electronic instrument transformers is described, including electronic voltage and current transformers (EVTs, ECTs) with both analog and digital outputs. A testing device prototype is developed. It is based on digital signal processing of the signals that are measured at the secondary outputs of the tested transformer and the reference transformer when the same excitation signal is fed to their primaries. The test that estimates the performance of the prototype has been carried out at the National Centre for High Voltage Measurement and the prototype is approved for testing transformers with precision class up to 0.2 at the industrial frequency (50 Hz or 60 Hz). The device is suitable for on-site testing due to its high accuracy, simple structure and low-cost hardware. PMID:22368510

Pan, Feng; Chen, Ruimin; Xiao, Yong; Sun, Weiming

2012-01-01

442

Implementation and experimental validation of a real-time PWM algorithm based on B-Spline carriers for three phase voltage source inverters  

Microsoft Academic Search

This paper presents the implementation and experimental results of an algebraic real-time sinusoidal pulse width modulation algorithm (SPWM) based on B-Spline carriers. B-spline functions are used as carrier signals with the aim to to reduce harmonic content of the three phase inverter output voltage. The presented algorithm eliminates the problem of B-spline recursive evaluation with convolution integrals or convolution sums

F. Genduso; R. Miceli; C. Rando

2009-01-01

443

Very-High-Frequency Resonant Boost Converters  

E-print Network

This paper presents a resonant boost topology suitable for very-high-frequency (VHF, 30-300 MHz) DC-DC power conversion. The proposed design features low device voltage stress, high efficiency over a wide load range, and ...

Perreault, David J.

444

Electro-optic high voltage sensor  

DOEpatents

A small sized electro-optic voltage sensor capable of accurate measurement of high levels of voltages without contact with a conductor or voltage source is provided. When placed in the presence of an electric field, the sensor receives an input beam of electromagnetic radiation into the sensor. A polarization beam displacer serves as a filter to separate the input beam into two beams with orthogonal linear polarizations. The beam displacer is oriented in such a way as to rotate the linearly polarized beams such that they enter a Pockels crystal having at a preferred angle of 45 degrees. The beam displacer is therefore capable of causing a linearly polarized beam to impinge a crystal at a desired angle independent of temperature. The Pockels electro-optic effect induces a differential phase shift on the major and minor axes of the input beam as it travels through the Pockels crystal, which causes the input beam to be elliptically polarized. A reflecting prism redirects the beam back through the crystal and the beam displacer. On the return path, the polarization beam displacer separates the elliptically polarized beam into two output beams of orthogonal linear polarization representing the major and minor axes. The system may include a detector for converting the output beams into electrical signals, and a signal processor for determining the voltage based on an analysis of the output beams. The output beams are amplitude modulated by the frequency of the electric field and the amplitude of the output beams is proportional to the magnitude of the electric field, which is related to the voltage being measured.

Davidson, James R. (Idaho Falls, ID); Seifert, Gary D. (Idaho Falls, ID)

2002-01-01

445

Effects of sinusoidal electromagnetic field on structure and function of different kinds of cell lines.  

PubMed

This study investigated that whether a 2 mT, 60 Hz, sinusoidal electromagnetic field (EMF) alters the structure and function of cells. This research compared the effects of EMF on four kinds of cell lines: hFOB 1.19 (fetal osteoblast), T/G HA-VSMC (aortic vascular smooth muscle cell), RPMI 7666 (B lymphoblast), and HCN-2 (cortical neuronal cell). Over 14 days, cells were exposed to EMF for 1, 3, or 6 hours per day (hrs/d). The results pointed to a cell type-specific reaction to EMF exposure. In addition, the cellular responses were dependent on duration of EMF exposure. In the present study, cell proliferation was the trait most sensitive to EMF. EMF treatment promoted growth of hFOB 1.19 and HCN-2 compared with control cells at 7 and 14 days of incubation. When the exposure time was 3 hrs/d, EMF enhanced the proliferation of RPMI 7666 but inhibited that of T/G HA- VSMC. On the other hand, the effects of EMF on cell cycle distribution, cell differentiation, and actin distribution were unclear. Furthermore, we hardly found any correlation between EMF exposure and gap junctional intercellular communication in hFOB 1.19. This study revealed that EMF might serve as a potential tool for manipulating cell proliferation. PMID:17191316

Sul, Ah Ram; Park, Si-Nae; Suh, Hwal

2006-12-31

446

50 Hz sinusoidal magnetic fields do not affect human lymphocyte activation and proliferation in vitro  

NASA Astrophysics Data System (ADS)

In the last 30 years, an increasing public concern about the possible harmful effects of electromagnetic fields generated by power lines and domestic appliances has pushed the scientific community to search for a correct and comprehensive answer to this problem. In this work the effects of exposure to 50 Hz sinusoidal magnetic fields, with a magnetic flux density of 0.05 mT and 2.5 mT (peak values), were studied on human peripheral blood mononuclear cells (PBMCs) collected from healthy young and elderly donors. Cell activation and proliferation were investigated by using flow cytometry techniques and 3H-TdR incorporation assays, respectively. The results obtained indicated that exposure to the fields altered neither DNA synthesis nor the capacity of lymphocytes to enter the activation phase and progress into the cell cycle. Thus, the conclusions are that two important functional phases of human lymphocytes, such as activation and proliferation, are not affected by exposures to 50 Hz magnetic fields similar to those found under power lines.

Capri, Miriam; Mesirca, Pietro; Remondini, Daniel; Carosella, Simona; Pasi, Sara; Castellani, Gastone; Franceschi, Claudio; Bersani, Ferdinando

2004-12-01

447

Time-domain Bayesian detection and estimation of noisy damped sinusoidal signals applied to NMR spectroscopy  

NASA Astrophysics Data System (ADS)

The problem of model detection and parameter estimation for noisy signals arises in different areas of science and engineering including audio processing, seismology, electrical engineering, and NMR spectroscopy. We have adopted the Bayesian modeling framework to jointly detect and estimate signal resonances. This considers a model of the time-domain complex free induction decay (FID) signal as a sum of exponentially damped sinusoidal components. The number of model components and component parameters are considered unknown random variables to be estimated. A Reversible Jump Markov Chain Monte Carlo technique is used to draw samples from the joint posterior distribution on the subspaces of different dimensions. The proposed algorithm has been tested on synthetic data, the 1H NMR FID of a standard of L-glutamic acid and a blood plasma sample. The detection and estimation performance is compared with Akaike information criterion (AIC), minimum description length (MDL) and the matrix pencil method. The results show the Bayesian algorithm superior in performance especially in difficult cases of detecting low-amplitude and strongly overlapping resonances in noisy signals.

Rubtsov, Denis V.; Griffin, Julian L.

2007-10-01

448

Experimental and theoretical investigation of the angular dependence of the Casimir force between sinusoidally corrugated surfaces  

NASA Astrophysics Data System (ADS)

In the current work we present the complete results for the measurement of normal Casimir force between a shallow and smooth sinusoidally corrugated gold coated sphere and a plate at various angles between the corrugations using an atomic force microscope. All measured data were compared with the theoretical approach using the proximity force approximation and theory based on derivative expansion. In both cases real material properties of the surfaces and nonzero temperature were taken into account. Special attention is paid to the description of electrostatic interactions between corrugated surfaces at different angles between corrugations and samples preparation and characterization. The measured forces are found to be in good agreement with the theory including correlation effects of geometry and material properties and deviate significantly from the predictions of the proximity force approximation approach. This provides the quantitative confirmation for the observation of diffraction-type effects that are disregarded within the PFA approach. The obtained results open new opportunities for control of the Casimir effect in micromechanical systems.

Banishev, A. A.; Wagner, J.; Emig, T.; Zandi, R.; Mohideen, U.

2014-06-01

449

Hepatic nerve growth factor induced by iron overload triggers defenestration in liver sinusoidal endothelial cells.  

PubMed

The fenestrations of liver sinusoidal endothelial cells (LSECs) play important roles in the exchange of macromolecules, solutes, and fluid between blood and surrounding liver tissues in response to hepatotoxic drugs, toxins, and oxidative stress. As excess iron is a hepatotoxin, LSECs may be affected by excess iron. In this study, we found a novel link between LSEC defenestration and hepatic nerve growth factor (NGF) in iron-overloaded mice. By Western blotting, NGF was highly expressed, whereas VEGF and HGF were not, and hepatic NGF mRNA levels were increased according to digital PCR. Immunohistochemically, NGF staining was localized in hepatocytes, while TrkA, an NGF receptor, was localized in LSECs. Scanning electron microscopy revealed LSEC defenestration in mice overloaded with iron as well as mice treated with recombinant NGF. Treatment with conditioned medium from iron-overloaded primary hepatocytes reduced primary LSEC fenestrations, while treatment with an anti-NGF neutralizing antibody or TrkA inhibitor, K252a, reversed this effect. However, iron-loaded medium itself did not reduce fenestration. In conclusion, iron accumulation induces NGF expression in hepatocytes, which in turn leads to LSEC defenestration via TrkA. This novel link between iron and NGF may aid our understanding of the development of chronic liver disease. PMID:25460199

Addo, Lynda; Tanaka, Hiroki; Yamamoto, Masayo; Toki, Yasumichi; Ito, Satoshi; Ikuta, Katsuya; Sasaki, Katsunori; Ohtake, Takaaki; Torimoto, Yoshihiro; Fujiya, Mikihiro; Kohgo, Yutaka

2015-01-01

450

Hepatic Sinusoidal Obstruction Syndrome Caused by Herbal Medicine: CT and MRI Features  

PubMed Central

Objective To describe the CT and MRI features of hepatic sinusoidal obstruction syndrome (HSOS) caused by herbal medicine Gynura segetum. Materials and Methods The CT and MRI features of 16 consecutive Gynura segetum induced HSOS cases (12 men, 4 women) were analyzed. Eight patients had CT; three patients had MRI, and the remaining five patients had both CT and MRI examinations. Based on their clinical presentations and outcomes, the patients were classified into three categories: mild, moderate, and severe. The severity of the disease was also evaluated radiologically based on the abnormal hepatic patchy enhancement in post-contrast CT or MRI images. Results Ascites, patchy liver enhancement, and main right hepatic vein narrowing or occlusion were present in all 16 cases. Hepatomegaly and gallbladder wall thickening were present in 14 cases (87.5%, 14/16). Periportal high intensity on T2-weighted images was present in 6 cases (75%, 6/8). Normal liver parenchymal enhancement surrounding the main hepatic vein forming a clover-like sign was observed in 4 cases (25%, 4/16). The extent of patchy liver enhancement was statistically associated with clinical severity classification (kappa = 0.565). Conclusion Ascites, patchy liver enhancement, and the main hepatic veins narrowing were the most frequent signs of herbal medicine induced HSOS. The grade of abnormal patchy liver enhancement was associated with the clinical severity. PMID:24643319

Zhou, Hua; Wang, Yi-Xiang J.; Lou, Hai-yan; Xu, Xiao-jun

2014-01-01

451

Age-related changes in human vestibulo-ocular reflexes: Sinusoidal rotation and caloric tests  

NASA Technical Reports Server (NTRS)

The dynamic response properties of horizontal vestibulo-ocular reflex (VOR) were characterized in 216 human subjects ranging in age from 7 to 81 years. The object of this cross-sectional study was to determine the effects of aging on VOR dynamics, and to identify the distributions of parameters which describe VOR responses to caloric and to sinusoidal rotational stimuli in a putatively normal population. Caloric test parameters showed no consistent trend with age. Rotation test parameters showed declining response amplitude and slightly less compensatory response phase with increasing age. The magnitudes of these changes were not large relative to the variability within the population. The age-related trends in VOR were not consistent with the anatomic changes in the periphery reported by others which showed an increasing rate of peripheral hair cell and nerve fiber loss in subjects over 55 years. The poor correlation between physiological and anatomical data suggest that adaptive mechanisms in the central nervous system are important in maintaining the VOR.

Peterka, R. J.; Black, F. O.; Schoenhoff, M. B.

1989-01-01

452

Sparse-view computed laminography with a spherical sinusoidal scan for nondestructive testing.  

PubMed

X-ray computed laminography is widely used in nondestructive testing of relatively flat objects using an oblique scanning configuration for data acquisition. In this work, a new scanning scheme is proposed in conjunction with the compressive-sensing-based image reconstruction for reducing imaging radiation dose and scanning time. We performed a numerical study comparing image qualities acquired by various scanning configurations that are practically implementable: single-arc, double-arc, oblique, and spherical-sinusoidal trajectories. A compressive-sensing-inspired total-variation (TV) minimization algorithm was used to reconstruct the images from the data acquired at only 40 projection views in those trajectories. It was successfully demonstrated that the proposed scanning scheme outperforms the others in terms of image contrast and spatial resolution, although the oblique scanning scheme showed a comparable resolution property. We believe that the proposed scanning method may provide a solution to fast and low-dose nondestructive testing of radiation-sensitive and highly integrated devices such as multilayer microelectronic circuit boards. PMID:25089394

Abbas, Sajid; Park, Miran; Min, Jonghwan; Kim, Ho Kyung; Cho, Seungryong

2014-07-28

453

Geosat crossover analysis in the tropical Pacific. Part 1: Constrained sinusoidal crossover adjustment  

NASA Technical Reports Server (NTRS)

A new method (constrained sinusoidal crossover adjustment) for removing the orbit error in satellite altimetry is tested (using crossovers accumulated in the first 91 days of the Geosat non-repeat era in the tropical Pacific) and found to have excellent qualities. Two features distinguish the new method from the conventional bias-and-tilt crossover adjustment. First, a sine wave (with wavelength equaling the circumference of the Earth) is used to represent the orbit error for each satellite revolution, instead of the bias-and-tilt (and curvature, if necessary) approach for each segment of the satellite ground track. Secondly, the indeterminacy of the adjustment process is removed by a simple constraint minimizing the amplitudes of the sine waves, rather than by fixing selected tracks. Overall the new method is more accurate, more efficient, and much less cumbersome than the old. The idea of restricting the crossover adjustment to crossovers between tracks that are less than certain days apart in order to preserve the large-scale long-term oceanic variability is also tested with inconclusive results because the orbit error was unusually nonstationary in the initial 91 days of the GEOSAT mission.

Tai, Chang-Kou

1988-01-01

454

Series-stacked medium voltage electronic voltage regulator  

Microsoft Academic Search

This paper discusses the development of a series- stacked medium-voltage electronic voltage regulator for the pur- pose of regulating the voltage on a 22 kV three-phase transmission line. The three-phase regulator consists of three independent 12.75 kV regulator cells, connected in a star configuration. Each regulator cell consists of an autotransformer with one common and two series windings. An AC-to-AC

Males Tomlinson; Dewald Abrie; Toit Mouton

2011-01-01

455

Effects of broad frequency vibration on cultured osteoblasts  

NASA Technical Reports Server (NTRS)

Bone is subjected in vivo to both high amplitude, low frequency strain, incurred by locomotion, and to low amplitude, broad frequency strain. The biological effects of low amplitude, broad frequency strain are poorly understood. To evaluate the effects of low amplitude strains ranging in frequency from 0 to 50 Hz on osteoblastic function, we seeded MC3T3-E1 cells into collagen gels and applied the following loading protocols for 3 min per day for either 3 or 7 days: (1) sinusoidal strain at 3 Hz, with 0-3000 microstrain peak-to-peak followed by 0.33 s resting time, (2) "broad frequency vibration" of low amplitude strain (standard deviation of 300 microstrain) including frequency components from 0 to 50 Hz, and (3) sinusoidal strain combined with broad frequency vibration (S + V). The cells were harvested on day 4 or 8. We found that the S + V stimulation significantly repressed cell proliferation by day 8. Osteocalcin mRNA was up-regulated 2.6-fold after 7 days of S + V stimulation, and MMP-9 mRNA was elevated 1.3-fold after 3 days of vibration alone. Sinusoidal stimulation alone did not affect the cell responses. No differences due to loading were observed in alkaline phosphatase activity and in mRNA levels of type I collagen, osteopontin, connexin 43, MMPs-1A, -3, -13. These results suggest that osteoblasts are more sensitive to low amplitude, broad frequency strain, and this kind of strain could sensitize osteoblasts to high amplitude, low frequency strain. This suggestion implies a potential contribution of stochastic resonance to the mechanical sensitivity of osteoblasts. Copyright 2002 Elsevier Science Ltd.

Tanaka, Shigeo M.; Li, Jiliang; Duncan, Randall L.; Yokota, Hiroki; Burr, David B.; Turner, Charles H.

2003-01-01

456

High voltage feedthrough bushing  

DOEpatents

A feedthrough bushing for a high voltage diode provides for using compression sealing for all sealing surfaces. A diode assembly includes a central conductor extending through the bushing and a grading ring assembly circumferentially surrounding and coaxial with the central conductor. A flexible conductive plate extends between and compressively seals against the central conductor and the grading ring assembly, wherein the flexibility of the plate allows inner and outer portions of the plate to axially translate for compression sealing against the central conductor and the grading ring assembly, respectively. The inner portion of the plate is bolted to the central conductor for affecting sealing. A compression beam is also bolted to the central conductor and engages the outer portion of the plate to urge the outer portion toward the grading ring assembly to obtain compression sealing therebetween.

Brucker, John P. (Espanola, NM)

1993-01-01

457

A combined uninterruptible power supply and dynamic voltage compensator using a flywheel energy storage system  

NASA Astrophysics Data System (ADS)

Due to recent technological advances in materials, power electronics, magnetic bearings and controls, the flywheel energy storage system has become a viable alternative to electrochemical batteries. The advantages of the flywheel system are its higher power density, insensitivity to environmental conditions, lack of hazardous materials and ease of checking the charge. One potential use is in a power distribution system. The flywheel energy storage system may be used as both an uninterruptible power supply as well as a means of dynamic voltage compensation to protect critical loads on radial distribution feeders. To perform dynamic voltage compensation, a comparison was performed which shows that the series injection of power is preferable to the shunt injection of power in utilizing the available kVA of the flywheel system motor/generator. The system was designed and modeled using the Electromagnetic Transients Program to ensure a proper dynamic response of the flywheel energy storage system in either mode of operation. The design incorporates a boost converter on the dc link to enable the load voltage to be maintained as the flywheel spins down. The same boost converter also allows for extended operation in the series compensation mode, by implementing a novel control scheme where sinusoidal pulse width modulation control is used for to compensate for smaller supply voltage dips, while the boost converter is used to control the compensation for larger supply voltage dips.

Weissbach, Robert Stephen

458

A high-efficiency low-voltage CMOS rectifier for harvesting energy in implantable devices.  

PubMed

We present, in this paper, a new full-wave CMOS rectifier dedicated for wirelessly-powered low-voltage biomedical implants. It uses bootstrapped capacitors to reduce the effective threshold voltage of selected MOS switches. It achieves a significant increase in its overall power efficiency and low voltage-drop. Therefore, the rectifier is good for applications with low-voltage power supplies and large load current. The rectifier topology does not require complex circuit design. The highest voltages available in the circuit are used to drive the gates of selected transistors in order to reduce leakage current and to lower their channel on-resistance, while having high transconductance. The proposed rectifier was fabricated using the standard TSMC 0.18 ?m CMOS process. When connected to a sinusoidal source of 3.3 V peak amplitude, it allows improving the overall power efficiency by 11% compared to the best recently published results given by a gate cross-coupled-based structure. PMID:23853177

Hashemi, S Saeid; Sawan, Mohamad; Savaria, Yvon

2012-08-01

459

High-resolution frequency determination of discrete signal components  

NASA Technical Reports Server (NTRS)

An important problem in many applications involves the determination of the frequency of a limited set of sinusoidal components in a time domain signal. The Fourier transform is used as the fundamental tool for conversion to the frequency domain. In the present investigation, an analysis is conducted of the errors inherent in the use of the Fourier transform without time domain windowing, and an algorithm is developed which makes it possible to obtain the frequency of the component signals with high accuracy. This algorithm combines the advantages of the Gaussian window with the computational efficiency of the Fast Fourier Transform (FFT).

Walton, E. K.

1984-01-01

460

Intermodulation electrostatic force microscopy for imaging surface photo-voltage  

NASA Astrophysics Data System (ADS)

We demonstrate an alternative to Kelvin Probe Force Microscopy for imaging surface potential. The open-loop, single-pass technique applies a low-frequency AC voltage to the atomic force microscopy tip while driving the cantilever near its resonance frequency. Frequency mixing due to the nonlinear capacitance gives intermodulation products of the two drive frequencies near the cantilever resonance, where they are measured with high signal to noise ratio. Analysis of this intermodulation response allows for quantitative reconstruction of the contact potential difference. We derive the theory of the method, validate it with numerical simulation and a control experiment, and we demonstrate its utility for fast imaging of the surface photo-voltage on an organic photo-voltaic material.

Borgani, Riccardo; Forchheimer, Daniel; Bergqvist, Jonas; Thorén, Per-Anders; Inganäs, Olle; Haviland, David B.

2014-10-01

461

Voltage-gated ion channels.  

PubMed

Voltage-dependent ion channels are membrane proteins that conduct ions at high rates regulated by the voltage across the membrane. They play a fundamental role in the generation and propagation of the nerve impulse and in cell homeostasis. The voltage sensor is a region of the protein bearing charged amino acids that relocate upon changes in the membrane electric field. The movement of the sensor initiates a conformational change in the gate of the conducting pathway thus controlling the flow of ions. Major advances in molecular biology, spectroscopy, and structural techniques are delineating the main features and possible structural changes that account for the function of voltage-dependent channels. PMID:15816170

Bezanilla, Francisco

2005-03-01

462

Methods for rapid frequency-domain characterization of leakage currents in silicon nanowire-based field-effect transistors  

PubMed Central

Summary Silicon nanowire-based field-effect transistors (SiNW FETs) have demonstrated the ability of ultrasensitive detection of a wide range of biological and chemical targets. The detection is based on the variation of the conductance of a nanowire channel, which is caused by the target substance. This is seen in the voltage–current behavior between the drain and source. Some current, known as leakage current, flows between the gate and drain, and affects the current between the drain and source. Studies have shown that leakage current is frequency dependent. Measurements of such frequency characteristics can provide valuable tools in validating the functionality of the used transistor. The measurements can also be an advantage in developing new detection technologies utilizing SiNW FETs. The frequency-domain responses can be measured by using a commercial sine-sweep-based network analyzer. However, because the analyzer takes a long time, it effectively prevents the development of most practical applications. Another problem with the method is that in order to produce sinusoids the signal generator has to cope with a large number of signal levels. This may become challenging in developing low-cost applications. This paper presents fast, cost-effective frequency-domain methods with which to obtain the responses within seconds. The inverse-repeat binary sequence (IRS) is applied and the admittance spectroscopy between the drain and source is computed through Fourier methods. The methods is verified by experimental measurements from an n-type SiNW FET. PMID:25161832

Yu, Xiao; Verho, Jarmo; Li, Tie; Kallio, Pasi; Vilkko, Matti; Gao, Anran; Wang, Yuelin

2014-01-01

463

Unified constant-frequency integration control of active power filters-steady-state and dynamics  

Microsoft Academic Search

An active power filter (APF) is a device that is connected in parallel to and cancels the reactive and harmonic currents from a group of nonlinear loads so that the resulting total current drawn from the AC mains is sinusoidal. This paper presents a unified constant-frequency integration (UCI) APF control method based on one-cycle control. This method employs an integrator

Keyue M. Smedley; Luowei Zhou; Chongming Qiao

2001-01-01

464

An analytical frequency-domain modeling of a Modular Multilevel Converter  

Microsoft Academic Search

The Modular Multilevel Converter (MMC) is a new topology for multilevel converters with potential for medium voltage and high voltage applications. This paper focuses on the modeling technique in the frequency domain of an MMC. Using this frequency domain modeling it is possible to analyze and predict the harmonic content in the arm current and capacitor voltages. In MMC, a

Hamed Nademi; Anandarup Das; Lars Norum

2012-01-01

465

The effects of acceleration on the mechanical impedance response of a primate model exposed to sinusoidal vibration  

Microsoft Academic Search

Criteria for developing active and passive isolation mechanisms for reducing the effects of whole-body vibration exposure\\u000a rely on a thorough understanding of the stiffness, damping, and resonance behaviors of the human or human surrogate body.\\u000a Three Rhesus monkeys were exposed to seated whole-body sinusoidal vibration between 3 and 20 Hz at 0.69 and 3.47 msec?2 rms (0.1 and 0.5 g

Suzanne D. Smith; Leon E. Kazarian

1994-01-01

466

Sinusoidal phase-modulating Fizeau interferometer using a self-pumped phase conjugator for surface profile measurements  

Microsoft Academic Search

A sinusoidal phase-modulating Fizeau interferometer using a BaTiO3 self-pumped phase conjugator is constructed to measure surface profiles of objects with a high accuracy. An object field is formed on a surface of a glass plate where the object wave interferes with its phase conjugate wave. Because the size of the glass plate can be much smaller than that of the

Xiangzhao Wang; Osami Sasaki; Yuuichi Takebayashi; Takamasa Suzuki; Takeo Maruyama

1994-01-01

467

Formation of Fenestrae in Murine Liver Sinusoids Depends on Plasmalemma Vesicle-Associated Protein and Is Required for Lipoprotein Passage  

PubMed Central

Liver sinusoidal endothelial cells (LSEC) are characterized by the presence of fenestrations that are not bridged by a diaphragm. The molecular mechanisms that control the formation of the fenestrations are largely unclear. Here we report that mice, which are deficient in plasmalemma vesicle-associated protein (PLVAP), develop a distinct phenotype that is caused by the lack of sinusoidal fenestrations. Fenestrations with a diaphragm were not observed in mouse LSEC at three weeks of age, but were present during embryonic life starting from embryonic day 12.5. PLVAP was expressed in LSEC of wild-type mice, but not in that of Plvap-deficient littermates. Plvap-/- LSEC showed a pronounced and highly significant reduction in the number of fenestrations, a finding, which was seen both by transmission and scanning electron microscopy. The lack of fenestrations was associated with an impaired passage of macromolecules such as FITC-dextran and quantum dot nanoparticles from the sinusoidal lumen into Disse's space. Plvap-deficient mice suffered from a pronounced hyperlipoproteinemia as evidenced by milky plasma and the presence of lipid granules that occluded kidney and liver capillaries. By NMR spectroscopy of plasma, the nature of hyperlipoproteinemia was identified as massive accumulation of chylomicron remnants. Plasma levels of low density lipoproteins (LDL) were also significantly increased as were those of cholesterol and triglycerides. In contrast, plasma levels of high density lipoproteins (HDL), albumin and total protein were reduced. At around three weeks of life, Plvap-deficient livers developed extensive multivesicular steatosis, steatohepatitis, and fibrosis. PLVAP is critically required for the formation of fenestrations in LSEC. Lack of fenestrations caused by PLVAP deficiency substantially impairs the passage of chylomicron remnants between liver sinusoids and hepatocytes, and finally leads to liver damage. PMID:25541982

Herrnberger, Leonie; Hennig, Robert; Kremer, Werner; Hellerbrand, Claus; Goepferich, Achim; Kalbitzer, Hans Robert; Tamm, Ernst R.

2014-01-01

468

VizieR Online Data Catalog: Semi-sinusoidal variability with CoRoT (de Medeiros+, 2013)  

NASA Astrophysics Data System (ADS)

Variability periods, amplitudes, and signal-to-noise ratio for 4,206 CoRoT rotating candidates, which present well-defined semi-sinusoidal photometric variations. In addition to variability parameters, CoRoT ID and run, equatorial coordinates, spectral type, luminosity class, and B and V magnitudes from the CoRoTSky database, as well as J, H, and Ks magnitudes from the 2MASS database are given. (1 data file).

de Medeiros, J. R.; Ferreira Lopes, C. E.; Leao, I. C.; Canto Martins, B. L.; Catelan, M.; Baglin, A.; Vieira, S.; Bravo, J. P.; Cortes, C.; de Freitas, D. B.; Janot-Pacheco, E.; Maciel, S. C.; Melo, C. H. F.; Osorio, Y.; Porto de Mello, G. F.; Valio, A.

2013-06-01

469

Low frequency resistance fluctuations in films of high temperature superconductors  

Microsoft Academic Search

Low-frequency voltage fluctuations in thin films of YBa2Cu3O(7-x) at and above the superconducting transition temperature have a spectral density proportional to the ratio of the average voltage across the film to the frequency. The ratio of the spectral density to the average voltage decreases markedly as the microstructure of the films is improved. In contrast to classic superconductors, the noise

P. Rosenthal; R. H. Hammond; M. R. Beasley; R. Leoni; Ph. Lerch; J. Clarke

1989-01-01

470

A compact 100 kV high voltage glycol capacitor  

NASA Astrophysics Data System (ADS)

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

Wang, Langning; Liu, Jinliang; Feng, Jiahuai

2015-01-01

471

Voltage Regulator Chip: Power Supplies on a Chip  

SciTech Connect

ADEPT Project: CPES at Virginia Tech is finding ways to save real estate on a computer's motherboard that could be used for other critical functions. Every computer processor today contains a voltage regulator that automatically maintains a constant level of electricity entering the device. These regulators contain bulky components and take up about 30% of a computer's motherboard. CPES at Virginia Tech is developing a voltage regulator that uses semiconductors made of gallium nitride on silicon (GaN-on-Si) and high-frequency soft magnetic material. These materials are integrated on a small, 3D chip that can handle the same amount of power as traditional voltage regulators at 1/10 the size and with improved efficiency. The small size also frees up to 90% of the motherboard space occupied by current voltage regulators.

None

2010-09-01

472

Flow and axial dispersion in a sinusoidal-walled tube: Effects of inertial and unsteady flows  

SciTech Connect

Dispersion in porous media flows has been the subject of much experimental, theoretical and numerical study. Here we consider a wavy-walled tube (a three-dimensional tube with sinusoidally-varying diameter) as a simplified conceptualization of flow in porous media, where constrictions represent pore throats and expansions pore bodies. A theoretical model for effective (macroscopic) longitudinal dispersion in this system has been developed by volume averaging the microscale velocity field. Direct numerical simulation using computational fluid dynamics (CFD) methods was used to compute velocity fields by solving the Navier-Stokes equations, and also to numerically solve the volume averaging closure problem, for a range of Reynolds numbers (Re) spanning the low-Re to inertial flow regimes, including one simulation at Re = 449 for which unsteady flow was observed. Dispersion values were computed using both the volume averaging solution and a random walk particle tracking method, and results of the two methods were shown to be consistent. Our results are compared to experimental measurements of dispersion in porous media and to previous theoretical results for the low-Re, Stokes flow regime. In the steady inertial regime we observe an power-law increase in effective longitudinal dispersion (DL) with Re, consistent with previous results. This rapid rate of increase is caused by trapping of solute in expansions due to flow separation (eddies). For the unsteady case (Re = 449), the rate of increase of DL with Re was smaller than that observed at lower Re. Velocity fluctuations in this regime lead to increased rates of solute mass transfer between the core flow and separated flow regions, thus diminishing the amount of tailing caused by solute trapping in eddies and thereby reducing longitudinal dispersion.

Richmond, Marshall C.; Perkins, William A.; Scheibe, Timothy D.; Lambert, Adam; Wood, Brian D.

2013-12-01

473

Classical and alternative activation of rat hepatic sinusoidal endothelial cells by inflammatory stimuli.  

PubMed

The ability of rat hepatic sinusoidal endothelial cells (HSEC) to become activated in response to diverse inflammatory stimuli was analyzed. Whereas the classical macrophage activators, IFN? and/or LPS upregulated expression of iNOS in HSEC, the alternative macrophage activators, IL-10 or IL-4+IL-13 upregulated arginase-1 and mannose receptor. Similar upregulation of iNOS and arginase-1 was observed in classically and alternatively activated Kupffer cells, respectively. Removal of inducing stimuli from the cells had no effect on expression of these markers, demonstrating that activation is persistent. Washing and incubation of IFN? treated cells with IL-4+IL-13 resulted in decreased iNOS and increased arginase-1 expression, while washing and incubation of IL-4+IL-13 treated cells with IFN? resulted in decreased arginase-1 and increased iNOS, indicating that classical and alternative activation of the cells is reversible. HSEC were more sensitive to phenotypic switching than Kupffer cells, suggesting greater functional plasticity. Hepatocyte viability and expression of PCNA, ?-catenin and MMP-9 increased in the presence of alternatively activated HSEC. In contrast, the viability of hepatocytes pretreated for 2 h with 5 mM acetaminophen decreased in the presence of classically activated HSEC. These data demonstrate that activated HSEC can modulate hepatocyte responses following injury. The ability of hepatocytes to activate HSEC was also investigated. Co-culture of HSEC with acetaminophen-injured hepatocytes, but not control hepatocytes, increased the sensitivity of HSEC to classical and alternative activating stimuli. The capacity of HSEC to respond to phenotypic activators may represent an important mechanism by which they participate in inflammatory responses associated with hepatotoxicity. PMID:23103612

Liu, Yinglin; Gardner, Carol R; Laskin, Jeffrey D; Laskin, Debra L

2013-02-01

474

Visual evoked responses to sinusoidal gratings presented in central and right visual fields: I  

SciTech Connect

The present study applies neuromagnetic measurement techniques to probe the neurophysiological processing of spatial frequency (SF) by normal human observers. By exploiting the temporal and spatial resolution of neuromagnetic measurements, we hope to discriminate and characterize underlying neural functions and explore their correlation with perceptual or behavioral performance measures. Spatial frequency analysis has proven a useful paradigm for the study of visual perception and has been applied in psychophysical studies as well as invasive anatomical and physiological studies of experimental animals. These approaches have produced evidence of specialized neural activity and network structure for the analysis of spatial frequency information. Because the encoding of spatial frequency is a function of neuronal receptive-field size and since receptive-field size varies as a function of retinal location, we have also examined effects of visual field on responses to stimuli of defined spatial frequency content. 10 refs., 3 figs.

George, J.S.; Aine, C.J.; Flynn, E.R.

1987-01-01

475

Psychophysical tuning curves for frequencies below 100 Hz.  

PubMed

Psychophysical tuning curves (PTCs) were measured for sinusoidal signals with frequency f(s)?= 31.5, 40, 50, 63, and 80 Hz, using sinusoidal and narrowband-noise maskers. For the former, conditions were included where a pair of beating tones was added to reduce the use of cues related to beats. Estimates of each subject's middle-ear transfer function (METF) were obtained from equal-loudness contours measured from 20 to 160 Hz. With decreasing f(s), the PTCs became progressively broadened and markedly asymmetrical, with shallow upper skirts and steep lower skirts. For the sinusoidal maskers, the tips were more irregular than for narrowband-noise maskers or when beating tones were added. For f(s)?= 31.5 and 40 Hz, the tips of the PTCs always fell above f(s). Allowing for the METF so as to infer underlying filter shapes resulted in flatter lower skirts, especially below 40 Hz, and reduced the frequency at the tips for f(s) between 31.5 and 50 Hz; however, the tips did not fall below 40 to 50 Hz. The bandwidths of the PTCs increased with decreasing f(s) below 80 Hz. However, bandwidths remained roughly constant if the METF was included as part of auditory filtering for frequencies below 40 Hz. PMID:21568419

Jurado, Carlos; Pedersen, Christian S; Moore, Brian C J

2011-05-01

476

Stochastic prediction of voltage sags in a large transmission system  

Microsoft Academic Search

This paper discusses two stochastic prediction methods for voltage sags and applies them to a 97-bus model of the 400 kV National Grid of England and Wales. The method of fault positions is most suitable for implementation in a software tool. It has been used to get exposed areas and sag frequencies for each bus. The results are presented in

Mohammed R. Qader; Math H. J. Bollen; Ron N. Allan

1999-01-01

477

Load insensitive electrical device. [power converters for supplying direct current at one voltage from a source at another voltage  

NASA Technical Reports Server (NTRS)

A class of power converters is described for supplying direct current at one voltage from a source at another voltage. It includes a simple passive circuit arrangement of solid-state switches, inductors, and capacitors by which the output voltage of the converter tends to remain constant in spite of changes in load. The switches are sensitive to the current flowing in the circuit and are employed to permit the charging of capacitance devices in accordance with the load requirements. Because solid-state switches (such as SCR's) may be used with relatively high voltage and because of the inherent efficiency of the invention that permits relatively high switching frequencies, power supplies built in accordance with the invention, together with their associated cabling, can be substantially lighter in weight for a given output power level and efficiency of operation than systems of the prior art.

Schwarz, F. C. (inventor)

1974-01-01

478

Current vs. Voltage Feedback Amplifiers  

E-print Network

Current vs. Voltage Feedback Amplifiers One question continuously troubles the analog design engi- neer: 'Which amplifier topology is better for my application, current feedback or voltage feedback) are not apparent. Today's CFB and VFB amplifiers have comparable performance, but there are cer- tain unique

Lanterman, Aaron

479

Temperature controlled high voltage regulator  

DOEpatents

A temperature controlled high voltage regulator for automatically adjusting the high voltage applied to a radiation detector is described. The regulator is a solid state device that is independent of the attached radiation detector, enabling the regulator to be used by various models of radiation detectors, such as gas flow proportional radiation detectors.

Chiaro, Jr., Peter J. (Clinton, TN); Schulze, Gerald K. (Knoxville, TN)

2004-04-20

480

How membrane proteins sense voltage  

Microsoft Academic Search

The ionic gradients across cell membranes generate a transmembrane voltage that regulates the function of numerous membrane proteins such as ion channels, transporters, pumps and enzymes. The mechanisms by which proteins sense voltage is diverse: ion channels have a conserved, positively charged transmembrane region that moves in response to changes in membrane potential, some G-protein coupled receptors possess a specific

Francisco Bezanilla

2008-01-01