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Sample records for frequency sinusoidal voltage

  1. The chording effect on core losses of three-phase induction motor under sinusoidal and PWM voltage supplies

    NASA Astrophysics Data System (ADS)

    Deshmukh, Ram; Moses, A. J.; Anayi, F.

    The core losses and the lower-order voltage harmonics of four different chorded motors fed from sinusoidal supply and inverter voltage supply were invigilated at no-load condition. All the four motors were tested with 4, 8 and 16 kHz switching frequencies and 30, 40, 50 and 60 Hz modulation frequencies The motor with 120° coil pitch has the least core losses and the lower-order voltage harmonics under sinusoidal and pulse width modulation (PWM) voltage supplies at all switching and modulation frequencies. The drop in the core losses for this motor was 46% and 53% under sinusoidal and PWM voltage supplies, respectively. The motor with 120° coil pitch is recommended to be used under sinusoidal and PWM voltage supplies.

  2. Self-mixing vibration measurement using emission frequency sinusoidal modulation

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

    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.

  3. High frequency breakdown voltage

    SciTech Connect

    Chu, Thanh Duy

    1992-03-01

    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.

  4. Frequency to Voltage Converter Analog Front-End Prototype

    NASA Technical Reports Server (NTRS)

    Mata, Carlos; Raines, Matthew

    2012-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Ahmed, Nabil A.

    2011-06-01

    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.

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

    DOEpatents

    Su, Gui-Jia [Knoxville, TN

    2005-11-29

    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.

  7. Sinusoidal frequency modulation on laser diode for frequency stabilization and displacement measuring interferometry

    NASA Astrophysics Data System (ADS)

    Aketagawa, Masato; Vu, Thanh-Tung; Yamazaki, Ryo

    2015-09-01

    In this paper, we propose the sinusoidal frequency modulation on a laser diode (LD) to achieve both frequency stabilization of the LD and displacement measurement with a homodyne interferometer. The central frequency of the LD is stabilized to a Doppler broadened absorption line of an iodine (I2) molecule near the wavelength of 633 nm. The frequency of the LD is modulated across the absorption line and synchronous detection is utilized to detect the absorption signal. A simple and low-cost homodyne displacement-measuring interferometer can be constructed that can attain high measurement resolution.

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

    NASA Astrophysics Data System (ADS)

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

    2013-10-01

    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 (C3Πu → B3Πg, 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.

  9. Improvement of stability of sinusoidally driven atmospheric pressure plasma jet using auxiliary bias voltage

    NASA Astrophysics Data System (ADS)

    Kim, Hyun-Jin; Kim, Jae Young; Kim, Jae Hyun; Kim, Dong Ha; Lee, Duck-Sik; Park, Choon-Sang; Park, Hyung Dal; Shin, Bhum Jae; Tae, Heung-Sik

    2015-12-01

    In this study, we have proposed the auxiliary bias pulse scheme to improve the stability of atmospheric pressure plasma jets driven by an AC sinusoidal waveform excitation source. The stability of discharges can be significantly improved by the compensation of irregular variation in memory voltage due to the effect of auxiliary bias pulse. From the parametric study, such as the width, voltage, and onset time of auxiliary bias pulse, it has been demonstrated that the auxiliary bias pulse plays a significant role in suppressing the irregular discharges caused by the irregular variation in memory voltage and stable discharge can be initiated with the termination of the auxiliary bias pulse. As a result of further investigating the effects of the auxiliary pulse scheme on the jet stability under various process conditions such as the distance between the jet head and the counter electrode, and carrier gas flow, the jet stability can be improved by adjusting the amplitude and number of the bias pulse depending on the variations in the process conditions.

  10. Comparative study of SVPWM (space vector pulse width modulation) & SPWM (sinusoidal pulse width modulation) based three phase voltage source inverters for variable speed drive

    NASA Astrophysics Data System (ADS)

    Ahmed, Waheed; Usman Ali, Syed M.

    2013-12-01

    We have performed comparative studies of Space Vector Pulse Width Modulation (SVPWM) and Sinusoidal Pulse Width Modulation (SPWM) techniques utilizing MATLAB tools. During these investigations, we carried out intensive simulations, comprehensively analyzed the obtained results and compared the harmonic density, power factor (PF), & switching losses of SVPWM and SPWM. It has been observed during investigations that if the switching frequency is high then losses due to harmonics are negligible, thus based on obtained results we suggested that the SVPWM technique is a more reliable solution. Because SVPWM utilizes DC bus voltage more efficiently, generates less Total Harmonic Distortion (THD) and has higher output quality it provides flexible control of output voltage and output frequency for Variable Speed Drive (VSD).

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

    PubMed

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

    2015-03-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

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

  13. Sinusoidal Siemens star spatial frequency response measurement errors due to misidentified target centers

    NASA Astrophysics Data System (ADS)

    Birch, Gabriel C.; Griffin, John C.

    2015-07-01

    Numerous methods are available to measure the spatial frequency response (SFR) of an optical system. A recent change to the ISO 12233 photography resolution standard includes a sinusoidal Siemens star test target. We take the sinusoidal Siemens star proposed by the ISO 12233 standard, measure system SFR, and perform an analysis of errors induced by incorrectly identifying the center of a test target. We show a closed-form solution for the radial profile intensity measurement given an incorrectly determined center and describe how this error reduces the measured SFR of the system. Using the closed-form solution, we propose a two-step process by which test target centers are corrected and the measured SFR is restored to the nominal, correctly centered values.

  14. Sinusoidal Siemens star spatial frequency response measurement errors due to misidentified target centers

    DOE PAGESBeta

    Birch, Gabriel Carisle; Griffin, John Clark

    2015-07-23

    Numerous methods are available to measure the spatial frequency response (SFR) of an optical system. A recent change to the ISO 12233 photography resolution standard includes a sinusoidal Siemens star test target. We take the sinusoidal Siemens star proposed by the ISO 12233 standard, measure system SFR, and perform an analysis of errors induced by incorrectly identifying the center of a test target. We show a closed-form solution for the radial profile intensity measurement given an incorrectly determined center and describe how this error reduces the measured SFR of the system. As a result, using the closed-form solution, we proposemore » a two-step process by which test target centers are corrected and the measured SFR is restored to the nominal, correctly centered values.« less

  15. Sinusoidal Siemens star spatial frequency response measurement errors due to misidentified target centers

    SciTech Connect

    Birch, Gabriel Carisle; Griffin, John Clark

    2015-07-23

    Numerous methods are available to measure the spatial frequency response (SFR) of an optical system. A recent change to the ISO 12233 photography resolution standard includes a sinusoidal Siemens star test target. We take the sinusoidal Siemens star proposed by the ISO 12233 standard, measure system SFR, and perform an analysis of errors induced by incorrectly identifying the center of a test target. We show a closed-form solution for the radial profile intensity measurement given an incorrectly determined center and describe how this error reduces the measured SFR of the system. As a result, using the closed-form solution, we propose a two-step process by which test target centers are corrected and the measured SFR is restored to the nominal, correctly centered values.

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

    PubMed Central

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

    2014-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Henning, G. Bruce

    2004-04-01

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

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

    PubMed

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

    2015-06-01

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

  19. Action of vibration on the response of cat muscle spindle Ia afferents to low frequency sinusoidal stretching.

    PubMed Central

    Matthews, P B; Watson, J D

    1981-01-01

    1. A study has been made of the effect of continuous vibration, at 150 Hz, upon the response of muscle spindle afferents to low frequency sinusoidal stretching (1 and 8 Hz). Using the soleus muscle of the anaesthetized cat, with severed ventral roots, recordings were made of single Ia afferents and of the massed Ia afferent discharges in the main bulk of the cut L7 dorsal root. 2. When the amplitude of vibration was large (50 micrometers, short pulses) and that of the sinusoidal stretching was not too great (50-100 micrometers, peak-to-peak) the discharge of the afferents was largely locked 1:1 to the vibration and the response to the sinusoidal stretching was abolished. 3. When the amplitude of the vibration was reduced to below that eliciting continuous afferent driving, then the response to sinusoidal stretching of any amplitude was often markedly increased. This arose through the vibration having a much more powerful excitatory action during the rising phase of the sinusoidal stretch than it did during the falling phase. 4. Averaged over a full cycle, the phase of the response to the sinusoidal stretching tended to be delayed during the vibration in comparison with the normal. This was largely dependent upon the afferents continuing to respond maximally to the vibration around the peak of the sinusoidal stretch, at which stage their unvibrated response is declining, rather than to a phase lag of the whole pattern of response. 5. The results are discussed in relation to the effects of vibration on tremor and the human stretch reflex, and on the determination of the frequency-response of spindle afferents. PMID:6458696

  20. Characterization of Wet Air Plasma Jet Powered by Sinusoidal High Voltage and Nanosecond Pulses for Plasma Agricultural Application

    NASA Astrophysics Data System (ADS)

    Takashima, Keisuke; Shimada, Keisuke; Konishi, Hideaki; Kaneko, Toshiro

    2015-09-01

    Not only for the plasma sterilization but also for many of plasma life-science applications, atmospheric pressure plasma devices that allowed us to control its state and reactive species production are deserved to resolve the roles of the chemical species. Influence of the hydroxyl radical and ozone on germination of conidia of a strawberry pathogen is presented. Water addition to air plasma jet significantly improves germination suppression performance, while measured reactive oxygen species (ROS) are reduced. Although the results show a negative correlation between ROS and the germination suppression, this infers the importance of chemical composition generated by plasma. For further control of the plasma product, a plasma jet powered by sinusoidal high voltage and nanosecond pulses is developed and characterized with the voltage-charge Lissajous. Control of breakdown phase and discharge power by pulse-imposed phase is presented. This work is supported by JSPS KAKENHI Grant-in-Aid for Young Scientists (B) Grant Number 15K17480 and Exploratory Research Grant Number 23644199.

  1. High-frequency graphene voltage amplifier.

    PubMed

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

    2011-09-14

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

  2. 46 CFR 111.01-17 - Voltage and frequency variations.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 4 2014-10-01 2014-10-01 false Voltage and frequency variations. 111.01-17 Section 111... ELECTRIC SYSTEMS-GENERAL REQUIREMENTS General § 111.01-17 Voltage and frequency variations. Unless... and +6 percent to −10 percent of rated voltage. This limitation does not address transient conditions....

  3. 46 CFR 111.01-17 - Voltage and frequency variations.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 4 2011-10-01 2011-10-01 false Voltage and frequency variations. 111.01-17 Section 111... ELECTRIC SYSTEMS-GENERAL REQUIREMENTS General § 111.01-17 Voltage and frequency variations. Unless... and +6 percent to −10 percent of rated voltage. This limitation does not address transient conditions....

  4. 46 CFR 111.01-17 - Voltage and frequency variations.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Voltage and frequency variations. 111.01-17 Section 111.01-17 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ELECTRICAL ENGINEERING ELECTRIC SYSTEMS-GENERAL REQUIREMENTS General § 111.01-17 Voltage and frequency variations....

  5. 46 CFR 111.01-17 - Voltage and frequency variations.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 4 2013-10-01 2013-10-01 false Voltage and frequency variations. 111.01-17 Section 111.01-17 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ELECTRICAL ENGINEERING ELECTRIC SYSTEMS-GENERAL REQUIREMENTS General § 111.01-17 Voltage and frequency variations....

  6. 46 CFR 111.01-17 - Voltage and frequency variations.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 4 2012-10-01 2012-10-01 false Voltage and frequency variations. 111.01-17 Section 111.01-17 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ELECTRICAL ENGINEERING ELECTRIC SYSTEMS-GENERAL REQUIREMENTS General § 111.01-17 Voltage and frequency variations....

  7. Performance analysis of cascaded h-bridge multilevel inverter using mixed switching frequency with various dc-link voltages

    NASA Astrophysics Data System (ADS)

    Citarsa, I. B. F.; Satiawan, I. N. W.; Wiryajati, I. K.; Supriono

    2016-01-01

    Multilevel inverters have been widely used in many applications since the technology is advantageous to increase the converter capability as well as to improve the output voltage quality. According to the applied switching frequency, multilevel modulations can be subdivided into three classes, i.e: fundamental switching frequency, high switching frequency and mixed switching frequency. This paper investigates the performance of cascaded H-bridge (CHB) multilevel inverter that is modulated using mixed switching frequency (MSF) PWM with various dc-link voltage ratios. The simulation results show the nearly sinusoidal load output voltages are successfully achieved. It is revealed that there is improvement in output voltages quality in terms of THD and low-order harmonics content. The CHB inverter that is modulated using MSF PWM with equal dc-link voltage ratio (½ Vdc: ½ Vdc) produces output voltage with the lowest low-order harmonics (less than 1% of fundamental) while the CHB inverter that is modulated using MSF PWM with un-equal dc-link voltage ratio (2/3 Vdc: 1/3 Vdc) produces a 7-level output voltage with the lowest THD (16.31%) compared to the other PWM methods. Improvement of the output voltage quality here is also in line with improvement of the number of available levels provided in the output voltage. Here only 2 cells H-bridge inverter (contain 8 switches) are needed to produce a 7- level output voltage, while in the conventional CHB inverter at least 3 cells of H-bridge inverter (contain 12 switches) are needed to produce a 7-level output voltage. Hence it is valuable in term of saving number of component.

  8. 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...

  9. Recording and analysis of (high-frequency) sinusoidal vibrations using computerized TV-holography

    NASA Astrophysics Data System (ADS)

    Ellingsrud, Svein; Lokberg, Ole J.; Pedersen, Hans M.

    1991-03-01

    The RETRA 1000 TV-holography system has been further developed for analysis of high frequency vibrations, using automatic data acquisition. Special phase shift algorithms are executed by means of a PC-based image processing system. The phase shifts are effected by a built in electro-optic modulator, controlled by a two channel high-resolution digital frequency synthesizer. The optical (speckle) and electronic noise is reduced, using an automatic speckle averaging technique. Amplitude and phase distributions can be calculated and presented for frequencies up to 10 MHz. The lower limit for amplitude detection is below 1 nm (for HeNe laser), while the relative phase distribution is given with less than 3° accuracy under stable conditions. We show results where the technique has been used to analyze various vibrating test objects like a ceramic "crystal", a high frequency loudspeaker and finally an underwater acoustic transducer. The crystal had resonant modes from 3,8 to 7,8 MHz

  10. Voltage and frequency dependence of prestin-associated charge transfer

    PubMed Central

    Sun, Sean X.; Farrell, Brenda; Chana, Matthew S.; Oster, George; Brownell, William E.; Spector, Alexander A.

    2009-01-01

    Membrane protein prestin is a critical component of the motor complex that generates forces and dimensional changes in cells in response to changes in the cell membrane potential. In its native cochlear outer hair cell, prestin is crucial to the amplification and frequency selectivity of the mammalian ear up to frequencies of tens of kHz. Other cells transfected with prestin acquire voltage-dependent properties similar to those of the native cell. The protein performance is critically dependent on chloride ions, and intrinsic protein charges also play a role. We propose an electro-diffusion model to reveal the frequency and voltage dependence of electric charge transfer by prestin. The movement of the combined charge (i.e., anion and protein charges) across the membrane is described with a Fokker-Planck equation coupled to a kinetic equation that describes the binding of chloride ions to prestin. We found a voltage-and frequency-dependent phase shift between the transferred charge and the applied electric field that determines capacitive and resistive components of the transferred charge. The phase shift monotonically decreases from zero to -90 degree as a function of frequency. The capacitive component as a function of voltage is bell-shaped, and decreases with frequency. The resistive component is bell-shaped for both voltage and frequency. The capacitive and resistive components are similar to experimental measurements of charge transfer at high frequencies. The revealed nature of the transferred charge can help reconcile the high-frequency electrical and mechanical observations associated with prestin, and it is important for further analysis of the structure and function of this protein. PMID:19490917

  11. Total Ionizing Dose Effects on Voltage-to-Frequency Converters

    NASA Technical Reports Server (NTRS)

    Lee, C.; Johnston, A.; Rax, B.

    1998-01-01

    This paper discusses total dose effects on voltage-to-frequency converters which impose different requirements on internal circuitry, and are also very high-precision devices (for example, linearity is typically specified between 0.002 and 0.05%).

  12. A high voltage nanosecond pulser with independently adjustable output voltage, pulse width, and pulse repetition frequency

    NASA Astrophysics Data System (ADS)

    Prager, James; Ziemba, Timothy; Miller, Kenneth; Carscadden, John; Slobodov, Ilia

    2014-10-01

    Eagle Harbor Technologies (EHT) is developing a high voltage nanosecond pulser capable of generating microwaves and non-equilibrium plasmas for plasma medicine, material science, enhanced combustion, drag reduction, and other research applications. The EHT nanosecond pulser technology is capable of producing high voltage (up to 60 kV) pulses (width 20-500 ns) with fast rise times (<10 ns) at high pulse repetition frequency (adjustable up to 100 kHz) for CW operation. The pulser does not require the use of saturable core magnetics, which allows for the output voltage, pulse width, and pulse repetition frequency to be fully adjustable, enabling researchers to explore non-equilibrium plasmas over a wide range of parameters. A magnetic compression stage can be added to improve the rise time and drive lower impedance loads without sacrificing high pulse repetition frequency operation. Work supported in part by the US Navy under Contract Number N00014-14-P-1055 and the US Air Force under Contract Number FA9550-14-C-0006.

  13. High-frequency voltage oscillations in cultured astrocytes.

    PubMed

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

    2015-05-11

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

  14. High-frequency voltage oscillations in cultured astrocytes

    PubMed Central

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

    2015-01-01

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

  15. Energy Conservation Using Dynamic Voltage Frequency Scaling for Computational Cloud

    PubMed Central

    Florence, A. Paulin; Shanthi, V.; Simon, C. B. Sunil

    2016-01-01

    Cloud computing is a new technology which supports resource sharing on a “Pay as you go” basis around the world. It provides various services such as SaaS, IaaS, and PaaS. Computation is a part of IaaS and the entire computational requests are to be served efficiently with optimal power utilization in the cloud. Recently, various algorithms are developed to reduce power consumption and even Dynamic Voltage and Frequency Scaling (DVFS) scheme is also used in this perspective. In this paper we have devised methodology which analyzes the behavior of the given cloud request and identifies the associated type of algorithm. Once the type of algorithm is identified, using their asymptotic notations, its time complexity is calculated. Using best fit strategy the appropriate host is identified and the incoming job is allocated to the victimized host. Using the measured time complexity the required clock frequency of the host is measured. According to that CPU frequency is scaled up or down using DVFS scheme, enabling energy to be saved up to 55% of total Watts consumption.

  16. Automatic frequency control of voltage-controlled oscillators

    NASA Technical Reports Server (NTRS)

    Kolbly, R. B.

    1969-01-01

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

  17. Optical frequency domain reflectometry based fiber Bragg grating vibration sensor array using sinusoidal current modulation of laser diodes

    NASA Astrophysics Data System (ADS)

    Wada, Atsushi; Tanaka, Satoshi; Takahashi, Nobuaki

    2015-09-01

    We present multipoint vibration sensing using fiber Bragg gratings and optical frequency domain refrectometry (OFDR). In OFDR based method, the maximum number of arrayed sensor can be few thousands and the measurement time is determined by wavelength scanning rate of a light source. In our sensor system, a laser diode is used as a wavelength scanning light source. Lasing wavelength of a laser diode can be modulated by changing its injection current. The injection current can be precisely modulated at high frequency up to 1 MHz using a laser-diode controller and wavelength scanning can be then easily achieved with a laser diode.

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

    DOEpatents

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

    2011-03-22

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

  19. Assessment of low-frequency hearing with narrow-band chirp-evoked 40-Hz sinusoidal auditory steady-state response.

    PubMed

    Wilson, Uzma S; Kaf, Wafaa A; Danesh, Ali A; Lichtenhan, Jeffery T

    2016-04-01

    Objective To determine the clinical utility of narrow-band chirp-evoked 40-Hz sinusoidal auditory steady state responses (s-ASSR) in the assessment of low-frequency hearing in noisy participants. Design Tone bursts and narrow-band chirps were used to respectively evoke auditory brainstem responses (tb-ABR) and 40-Hz s-ASSR thresholds with the Kalman-weighted filtering technique and were compared to behavioral thresholds at 500, 2000, and 4000 Hz. A repeated measure ANOVA and post-hoc t-tests, and simple regression analyses were performed for each of the three stimulus frequencies. Study sample Thirty young adults aged 18-25 with normal hearing participated in this study. Results When 4000 equivalent response averages were used, the range of mean s-ASSR thresholds from 500, 2000, and 4000 Hz were 17-22 dB lower (better) than when 2000 averages were used. The range of mean tb-ABR thresholds were lower by 11-15 dB for 2000 and 4000 Hz when twice as many equivalent response averages were used, while mean tb-ABR thresholds for 500 Hz were indistinguishable regardless of additional response averaging. Conclusion Narrow-band chirp-evoked 40-Hz s-ASSR requires a ∼15 dB smaller correction factor than tb-ABR for estimating low-frequency auditory threshold in noisy participants when adequate response averaging is used. PMID:26795555

  20. Fringe projection with a sinusoidal phase grating.

    PubMed

    Stoykova, Elena; Minchev, Georgi; Sainov, Ventseslav

    2009-08-20

    Phase-shifting profilometry requires projection of sinusoidal fringes on a 3D object. We analyze the visibility and frequency content of fringes created by a sinusoidal phase grating at coherent illumination. We derive an expression for the intensity of fringes in the Fresnel zone and measure their visibility and frequency content for a grating that has been interferometrically recorded on a holographic plate. Both evaluation of the systematic errors due to the presence of higher harmonics by simulation of a profilometric measurement and measurement of 3D coordinates of test objects confirm the good performance of the sinusoidal phase grating as a projective element. In addition, we prove theoretically that in comparison with a sinusoidal amplitude grating this grating produces better quality of fringes in the near-infrared region. Sinusoidal phase gratings are fabricated easily, and their implementation in fringe projection profilometry facilitates construction of portable, small size, and low-cost devices. PMID:19696868

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

    SciTech Connect

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

    2007-05-14

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

  2. Electronic Frequency Converter Controls A. C. Voltage Using Fixed Power Factor Method

    NASA Astrophysics Data System (ADS)

    Kunomura, Ken; Onishi, Mitsuru; Kai, Masahiko; Iio, Naotaka; Otsuki, Midori; Ishizuka, Tomotsugu

    In Tokaido Shinkansen, the power of a feeding substation increases in a short time because the train schedule is of high density and the acceleration performance of the rolling stock has improved. If the load power of the feeding substation increases further, the feeder voltage cannot be maintained when the power converter supplies only the reactive power. Because such a case was assumed in the frequency conversion section, we developed the Electronic Frequency Converter controls the A. C. voltage using the fixed power factor method. The Electronic Frequency Converter is under construction in the Numazu frequency conversion substation. We describe the domination of A. C. voltage control using the fixed power factor method.

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

    NASA Technical Reports Server (NTRS)

    Honnell, M. A.

    1975-01-01

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

  4. Collisionless sheath heating in current-driven capacitively coupled plasma discharges via higher order sinusoidal signals

    NASA Astrophysics Data System (ADS)

    Sharma, S.; Mishra, S. K.; Kaw, P. K.; Das, A.; Sirse, N.; Turner, M. M.

    2015-04-01

    Collisionless heating of the electrons in the vicinity of the sheath region corresponding to higher order sinusoidal signals in a current-driven radio-frequency capacitively coupled plasma discharge has been investigated analytically and further verified by particle-in-cell simulation. The simulation results for collisionless sheath heating are found to be in good agreement with analytical predictions. In contrast to the voltage driven case, it is demonstrated that a pure sinusoidal waveform gives maximum electron sheath heating with a current-driven configuration and the ion energy can be controlled by varying the pulse width.

  5. Radio frequency current-voltage probe for impedance and power measurements in multi-frequency unmatched loads.

    PubMed

    Lafleur, T; Delattre, P A; Booth, J P; Johnson, E V; Dine, S

    2013-01-01

    A broad-band, inline current-voltage probe, with a characteristic impedance of 50 Ω, is presented for the measurement of voltage and current waveforms, impedance, and power in rf systems. The probe, which uses capacitive and inductive sensors to determine the voltage and current, respectively, can be used for the measurement of single or multi-frequency signals into both matched and unmatched loads, over a frequency range of about 1-100 MHz. The probe calibration and impedance/power measurement technique are described in detail, and the calibrated probe results are compared with those obtained from a vector network analyzer and other commercial power meters. Use of the probe is demonstrated with the measurement of power into an unmatched capacitively coupled plasma excited by multi-frequency tailored voltage waveforms. PMID:23387681

  6. Sinusoidally Modulated Graphene Leaky-Wave Antenna for Electronic Beamscanning at THz

    NASA Astrophysics Data System (ADS)

    Esquius-Morote, Marc; Gomez-Diaz, Juan Sebastian; Perruisseau-Carrier, Julien

    2014-01-01

    This paper proposes the concept, analysis and design of a sinusoidally-modulated graphene leaky-wave antenna with beam scanning capabilities at a fixed frequency. The antenna operates at terahertz frequencies and is composed of a graphene sheet transferred onto a back-metallized substrate and a set of polysilicon DC gating pads located beneath it. In order to create a leaky-mode, the graphene surface reactance is sinusoidally-modulated via graphene's field effect by applying adequate DC bias voltages to the different gating pads. The pointing angle and leakage rate can be dynamically controlled by adjusting the applied voltages, providing versatile beamscanning capabilities. The proposed concept and achieved performance, computed using realistic material parameters, are extremely promising for beamscanning at THz frequencies, and could pave the way to graphene-based reconfigurable transceivers and sensors.

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

    PubMed

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

    2015-04-01

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

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

    PubMed

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

    2007-09-01

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

  9. The role of the relative voltage and phase for frequency coupling in a dual-frequency capacitively coupled plasma

    SciTech Connect

    O'Connell, D.; Gans, T.; Semmler, E.; Awakowicz, P.

    2008-08-25

    Frequency coupling in multifrequency discharges is a complex nonlinear interaction of the different frequency components. An alpha-mode low pressure rf capacitively coupled plasma operated simultaneously with two frequencies is investigated and the coupling of the two frequencies is observed to greatly influence the excitation and ionization within the discharge. Through this, plasma production and sustainment are dictated by the corresponding electron dynamics and can be manipulated through the dual-frequency sheath. These mechanisms are influenced by the relative voltage and also the relative phase of the two frequencies.

  10. Stabilization of Gyrotron Frequency by PID Feedback Control on the Acceleration Voltage

    NASA Astrophysics Data System (ADS)

    Khutoryan, E. M.; Idehara, T.; Kuleshov, A. N.; Tatematsu, Y.; Yamaguchi, Y.; Matsuki, Y.; Fujiwara, T.

    2015-12-01

    The results of frequency stabilization by proportional-integral-derivative (PID) feedback control of acceleration voltage in the 460-GHz Gyrotron FU CW GVI (the official name in Osaka University is Gyrotron FU CW GOI) are presented. The experiment was organized on the basis of the frequency modulation by modulation of acceleration voltage of beam electrons. The frequency stabilization during 10 h experiment was better than 10-6, which is compared with the results of the frequency deviation in free-running gyrotron operation.

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

    NASA Technical Reports Server (NTRS)

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

    1982-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

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

  13. Low-frequency switching voltage regulators for terrestrial photovoltaic systems

    NASA Technical Reports Server (NTRS)

    Delombard, R.

    1984-01-01

    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.

  14. Frequency-dependent capacitance-voltage hysteresis in ferroelectric liquid crystals: An effect of the frequency dependence of dielectric biaxiality

    NASA Astrophysics Data System (ADS)

    Rahman, Muklesur; Kundu, S. K.; Chaudhuri, B. K.; Yoshizawa, A.

    2005-07-01

    Using the concept of the Preisach model for a ferroelectric capacitor, we have analyzed the behavior of frequency (f)-dependent polarization reversal in surface-stabilized ferroelectric liquid crystals (SSFLCs) under an external field. At a fixed temperature, the peak height of the capacitance-voltage hysteresis loop is found to be decreasing with an increasing number of polarization cycles up to a certain typical value of frequency (e.g., fc) being different for different ferroelectric liquid crystals (FLCs). We also observed an inversion (a well instead of a peak) in the hysteresis loops appearing above a typical higher frequency denoted fi. The values of capacitance of the FLC capacitors became almost independent of the voltage for the frequencies between fc and fi. The frequency dependence of dielectric biaxiality in the SSFLCs is directly attributed to the appearance of such behavior.

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

    SciTech Connect

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

    1980-07-01

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

  16. Effects of frequencies of AC modulation voltage on piezoelectric-induced images using atomic force microscopy

    SciTech Connect

    Xu, C.H. . E-mail: mmcjxu@polyu.edu.hk; Woo, C.H.; Shi, S.Q.; Wang, Y.

    2004-07-15

    Lead zirconate titanate (PZT) thin film is prepared by sol-gel method on Pt/Ti electrode/SiO{sub 2}/Si wafer. Local poling is performed on the PZT film using an atomic force microscope (AFM). The topography and piezoelectric-induced (PEI) images on the polarized PZT film are recorded using AFM at piezo-responsive mode, operated with an AC voltage at varying frequencies. The best PEI image was obtained at the frequency around 300 kHz. It is explained that the change of piezoelectric vibrations and input noise signals with the frequency of AC modulation voltage affects the intensity of PEI images.

  17. Modeling of a single-cycle current generator while forming a quasi-sinusoidal current

    NASA Astrophysics Data System (ADS)

    Grebennikov, V. V.; Yaroslavtsev, E. V.; Slobodenuk, A. B.; Evtushenko, T. G.

    2016-04-01

    The paper presents the results of investigation of the influence of the output voltage magnitude on the operating frequency of the switch in the single-cycle quasi-sinusoidal current generator circuit. Analytical expressions for calculating the time parameters for transients in the circuit under given assumptions have been obtained. The results presented in the paper can be used in the design of converters of this type.

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

    SciTech Connect

    Skowroński, Witold Frankowski, Marek; Stobiecki, Tomasz; Wrona, Jerzy; Ogrodnik, Piotr; Barnaś, Józef

    2014-08-18

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

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

    PubMed Central

    Hou, Yubin; Lu, Qingyou

    2014-01-01

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

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

    PubMed

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

    2015-05-01

    We present a novel radio-frequency (RF) power supply and impedance matching to drive technological plasmas with customized voltage waveforms. It is based on a system of phase-locked RF generators that output single frequency voltage waveforms corresponding to multiple consecutive harmonics of a fundamental frequency. These signals are matched individually and combined to drive a RF plasma. Electrical filters are used to prevent parasitic interactions between the matching branches. By adjusting the harmonics' phases and voltage amplitudes individually, any voltage waveform can be approximated as a customized finite Fourier series. This RF supply system is easily adaptable to any technological plasma for industrial applications and allows the commercial utilization of process optimization based on voltage waveform tailoring for the first time. Here, this system is tested on a capacitive discharge based on three consecutive harmonics of 13.56 MHz. According to the Electrical Asymmetry Effect, tuning the phases between the applied harmonics results in an electrical control of the DC self-bias and the mean ion energy at almost constant ion flux. A comparison with the reference case of an electrically asymmetric dual-frequency discharge reveals that the control range of the mean ion energy can be significantly enlarged by using more than two consecutive harmonics. PMID:26026522

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

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2010-11-01

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

  3. Improved frequency/voltage converters for fast quartz crystal microbalance applications

    SciTech Connect

    Torres, R.; Kim, L. To Thi; Garcia, J. V.; Arnau, A.

    2008-04-15

    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.

  4. Sinusoids and Phasors.

    ERIC Educational Resources Information Center

    Balabanian, Norman; Root, Augustin A.

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

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

    NASA Astrophysics Data System (ADS)

    Kato, Toshiji; Inoue, Kaoru; Donomoto, Yoshihisa

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

  6. Microvascular filling pattern in rat liver sinusoids during vagal stimulation.

    PubMed Central

    Koo, A; Liang, I Y

    1979-01-01

    1. The terminal microcirculation in the transilluminated ventral margin of the rat liver was observed and recorded by a video-microscope system. The volumetric flow rate in a liver sinusoid was calculated from the observed diameter of the sinusoid and the intra-sinusoid erythrocyte flow velocity. 2. The topographic distribution of liver sinusoids within an arbitrary boundary of a microscopic field of terminal liver microcirculation was observed and the total inflow and outflow in the field were determined. 3. Both vagus nerves at the lower end of the oesophagus were stimulated at supramaximal voltage. Vagal stimulation dilated the calibre of liver sinusoids and paradoxically diminished the erythrocyte flow velocity in each individual liver sinusoid, but the total volumetric flows in a microscopic field remained unchanged. 4. Vagal stimulation also increased the number of liver sinusoids in a microscopic field by opening previously closed liver sinusoids. This recruitment contributed two-thirds of the total increase of the sinusoidal capacity while the other one third was the result of distension of existing liver sinusoids. Images Plate 1 PMID:521923

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

    NASA Technical Reports Server (NTRS)

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

    1981-01-01

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

  8. On the profile of frequency and voltage dependent interface states and series resistance in MIS structures

    NASA Astrophysics Data System (ADS)

    Dökme, İlbilge; Altındal, Şemsettin

    2007-04-01

    The variation in the capacitance-voltage ( C- V) and conductance-voltage ( G/ ω- V) characteristics of Au/SiO 2/n-Si metal-insulator-semiconductor (MIS) structure have been systematically investigated as a function of frequencies in the frequency range 0.5 kHz-10 MHz at room temperature. In addition, the forward and reverse bias current-voltage ( I- V) characteristics of this structure were measured at room temperature. The high value of ideality factor was attributed to the high density of interface states localized at Si/SiO 2 interface and interfacial oxide layer. The density of interface states ( Nss) and the series resistance ( Rss) were calculated from I- V and C- V measurements using different methods and the effect of them on C- V and G/ω- V characteristics were deeply researched. At the same energy position near the top of valance band, the calculated Nss values, obtained without taking into account the series resistance of the devices almost one order of magnitude larger than Nss values obtained by taking into account Rss values. It is found that the C- V and G/ω- V curves exhibit a peak at low frequencies and the peak values of C and G/ ω decrease with increasing frequency. Also, the plots of Rs as a function of bias give two peaks in the certain voltage range at low frequencies. These observations indicate that at low frequencies, the charges at interface states can easily follow an AC signal and the number of them increases with decreasing frequency. The I- V, C- V and G/ ω- V characteristics of the MIS structure are affected not only with Rs but also Nss. Experimental results show that both the Rs and Co values should be taken into account in determining frequency-dependent electrical characteristics.

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

    NASA Astrophysics Data System (ADS)

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

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

  10. Static current-voltage characteristics for radio-frequency induction discharge

    SciTech Connect

    Budyansky, A.; Zykov, A.

    1995-12-31

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

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

  12. Fast Rise Time and High Voltage Nanosecond Pulses at High Pulse Repetition Frequency

    NASA Astrophysics Data System (ADS)

    Miller, Kenneth E.; Ziemba, Timothy; Prager, James; Picard, Julian; Hashim, Akel

    2015-09-01

    Eagle Harbor Technologies (EHT), Inc. is conducting research to decrease the rise time and increase the output voltage of the EHT Nanosecond Pulser product line, which allows for independently, user-adjustable output voltage (0 - 20 kV), pulse width (20 - 500 ns), and pulse repetition frequency (0 - 100 kHz). The goals are to develop higher voltage pulses (50 - 60 kV), decrease the rise time from 20 to below 10 ns, and maintain the high pulse repetition capabilities. These new capabilities have applications to pseudospark generation, corona production, liquid discharges, and nonlinear transmission line driving for microwave production. This work is supported in part by the US Navy SBIR program.

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

    NASA Astrophysics Data System (ADS)

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

    2010-07-01

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

  14. Tuning of liquid-crystal birefringence using a square ac variable frequency voltage

    NASA Astrophysics Data System (ADS)

    Hamdi, Rachid; Falih Bendimerad, Djalal; Benkelfat, Badr-Eddine; Vinouze, Bruno

    2015-10-01

    We demonstrate that the birefringence of the liquid-crystal cell (LCC) can be varied by applying different frequency values of a single applied ac square voltage. For the experimental evaluation of the birefringence, associated with a certain wavelength λ, as a function of the frequency F LCC of the electrical signal applied to the LCC, we use, for the first time to our knowledge, what we call here a frequency-dependent transmission technique. It consists in measuring the transmission responses between crossed and parallel polarizers as a function of the frequency F LCC. Experimental tests were carried out using a 7 μm-thick E63 nematic LCC and a laser source emitting at λ = 1.55 μm with a launch power of -3 dBm. The tuning voltage V LCC applied to the LCC is an alternative square wave electrical signal whose frequency ranges from 0.5 to 15 kHz. The peak to peak amplitude of the electrical signal is 5 V. The curve of the measured variations of the optical path difference of the LCC versus the frequency F LCC has a positive slope. Application to the tuning of the center wavelength of the transmission response of a one stage hybrid birefringent filter is shown as a proof-of-principle test.

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

    SciTech Connect

    Yamaura, Michiteru

    2006-06-19

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

  16. Compact high voltage, high peak power, high frequency transformer for converter type modulator applications

    NASA Astrophysics Data System (ADS)

    Reghu, T.; Mandloi, V.; Shrivastava, Purushottam

    2016-04-01

    The design and development of a compact high voltage, high peak power, high frequency transformer for a converter type modulator of klystron amplifiers is presented. The transformer has been designed to operate at a frequency of 20 kHz and at a flux swing of ±0.6 T. Iron (Fe) based nanocrystalline material has been selected as a core for the construction of the transformer. The transformer employs a specially designed solid Teflon bobbin having 120 kV insulation for winding the high voltage secondary windings. The flux swing of the core has been experimentally found by plotting the hysteresis loop at actual operating conditions. Based on the design, a prototype transformer has been built which is per se a unique combination of high voltage, high frequency, and peak power specifications. The transformer was able to provide 58 kV (pk-pk) at the secondary with a peak power handling capability of 700 kVA. The transformation ratio was 1:17. The performance of the transformer is also presented and discussed.

  17. Compact high voltage, high peak power, high frequency transformer for converter type modulator applications.

    PubMed

    Reghu, T; Mandloi, V; Shrivastava, Purushottam

    2016-04-01

    The design and development of a compact high voltage, high peak power, high frequency transformer for a converter type modulator of klystron amplifiers is presented. The transformer has been designed to operate at a frequency of 20 kHz and at a flux swing of ±0.6 T. Iron (Fe) based nanocrystalline material has been selected as a core for the construction of the transformer. The transformer employs a specially designed solid Teflon bobbin having 120 kV insulation for winding the high voltage secondary windings. The flux swing of the core has been experimentally found by plotting the hysteresis loop at actual operating conditions. Based on the design, a prototype transformer has been built which is per se a unique combination of high voltage, high frequency, and peak power specifications. The transformer was able to provide 58 kV (pk-pk) at the secondary with a peak power handling capability of 700 kVA. The transformation ratio was 1:17. The performance of the transformer is also presented and discussed. PMID:27131709

  18. Fast optical frequency sweeping using voltage controlled oscillator driven single sideband modulation combined with injection locking.

    PubMed

    Wang, Jian; Chen, Dijun; Cai, Haiwen; Wei, Fang; Qu, Ronghui

    2015-03-23

    An ultrafast optical frequency sweeping technique for narrow linewidth lasers is reported. This technique exploits the large frequency modulation bandwidth of a wideband voltage controlled oscillator (VCO) and a high speed electro-optic dual parallel Mach-Zehnder modulator (DPMZM) which works on the state of carrier suppressed single sideband modulation(CS-SSB). Optical frequency sweeping of a narrow linewidth fiber laser with 3.85 GHz sweeping range and 80 GHz/μs tuning speed is demonstrated, which is an extremely high tuning speed for frequency sweeping of narrow linewidth lasers. In addition, injection locking technique is adopted to improve the sweeper's low optical power output and small side-mode suppression ratio (SMSR). PMID:25837048

  19. Sensorless optimal sinusoidal brushless direct current for hard disk drives

    NASA Astrophysics Data System (ADS)

    Soh, C. S.; Bi, C.

    2009-04-01

    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.

  20. Investigation of the frequency response of constant voltage anemometers in turbulent flows

    NASA Astrophysics Data System (ADS)

    Sadeghi Hassanlouei, Atabak

    A commercially available anemometer system considered as a prototype, the constant voltage anemometer (CVA), is presented and its working principle is studied and analyzed. We detail the different procedures and corrections that have to be applied to voltage signals to deduce corresponding velocity signals, including the effect of the thermal inertia of the sensor. Results are compared to another anemometer system widely used in research and industry, the constant temperature anemometer (CTA), for validation requirements. Measurements are performed in the turbulent region of a subsonic axisymmetric jet and include mean velocities, root-mean-square (rms) values of velocity fluctuations and power spectral densities. In the same range of operation, we show that the two instruments give similar results. The CVA anemometer slightly underestimates the rms velocity values given by the CTA anemometer which is attributed to a non-linear effect. We show that the cut-off frequency of the CVA system is higher than the more commonly used CTA system, and that the electronic noise level is lower. The constant voltage anemometer is thus an excellent alternative to the constant temperature anemometer for low turbulent flows with rich frequency content, such as supersonic and hypersonic flows.

  1. High-frequency stimulation produces a transient blockade of voltage-gated currents in subthalamic neurons.

    PubMed

    Beurrier, C; Bioulac, B; Audin, J; Hammond, C

    2001-04-01

    The effect of high-frequency stimulation (HFS) of the subthalamic nucleus (STN) was analyzed with patch-clamp techniques (whole cell configuration, current- and voltage-clamp modes) in rat STN slices in vitro. A brief tetanus, consisting of 100-micros bipolar stimuli at a frequency of 100--250 Hz during 1 min, produced a full blockade of ongoing STN activity whether it was in the tonic or bursting mode. This HFS-induced silence lasted around 6 min after the end of stimulation, was frequency dependent, could be repeated without alteration, and was not synaptically induced as it was still observed in the presence of blockers of ionotropic GABA and glutamate receptors or in the presence of cobalt at a concentration (2 mM) that blocks voltage-gated Ca(2+) channels and synaptic transmission. During HFS-induced silence, the following alterations were observed: the persistent Na(+) current (I(NaP)) was totally blocked (by 99%), the Ca(2+)-mediated responses were strongly reduced including the posthyperpolarization rebound (-62% in amplitude) and the plateau potential (-76% in duration), suggesting that T- and L-type Ca(2+) currents are transiently depressed by HFS, whereas the Cs(+)-sensitive, hyperpolarization-activated cationic current (I(h)) was little affected. Thus a high-frequency tetanus produces a blockade of the spontaneous activities of STN neurons as a result of a strong depression of intrinsic voltage-gated currents underlying single-spike and bursting modes of discharge. These effects of HFS, which are completely independent of synaptic transmission, provide a mechanism for interrupting ongoing activities of STN neurons. PMID:11287459

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

  3. Sinusoidal Forcing of Interfacial Films

    NASA Astrophysics Data System (ADS)

    Rasheed, Fayaz; Raghunandan, Aditya; Hirsa, Amir; Lopez, Juan

    2015-11-01

    Fluid transport, in vivo, is accomplished via pumping mechanisms of the heart and lungs, which results in biological fluids being subjected to oscillatory shear. Flow is known to influence biological macromolecules, but predicting the effect of shear is incomplete without also accounting for the influence of complex interfaces ubiquitous throughout the body. Here, we investigated the oscillatory response of the structure of aqueous interfacial films using a cylindrical knife edge viscometer. Vitamin K1 was used as a model monolayer because its behaviour has been thoroughly quantified and it doesn't show any measurable hysteresis. The monolayer was subjected to sinusoidal forcing under varied conditions of surface concentrations, periodic frequencies, and knife edge amplitudes. Particle Image Velocimetry(PIV) data was collected using Brewster Angle Microscopy(BAM), revealing the influence of oscillatory interfacial shear stress on the monolayer. Insights were gained as to how the velocity profile dampens at specific distances from the knife edge contact depending on the amplitude, frequency, and concentration of Vitamin K1. Supported by NNX13AQ22G, National Aeronautics and Space Administration.

  4. 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

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

    2014-01-01

    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

  5. Plasma characteristics in non-sinusoidally excited CCP discharges

    NASA Astrophysics Data System (ADS)

    Lafleur, Trevor; Booth, Jean-Paul

    2012-10-01

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

  6. Radio-frequency sheath voltages and slow wave electric field spatial structure

    NASA Astrophysics Data System (ADS)

    Colas, Laurent; Lu, Ling-Feng; Křivská, Alena; Jacquot, Jonathan

    2015-12-01

    We investigate theoretically how sheath radio-frequency (RF) oscillations relate to the spatial structure of the RF parallel electric field emitted by Ion Cyclotron (IC) wave launchers, using a simple model of Slow Wave (SW) evanescence coupled with Direct Current (DC) plasma biasing via sheath boundary conditions in a plasma-filled 2-dimensional (parallel, radial) rectangle. Within a "wide sheaths" asymptotic regime, valid for large-amplitude near RF fields, our model becomes partly linear: the sheath oscillating voltage at open field line boundaries is a linear combination of elementary contributions by every source point of the radiated RF field map. These individual contributions are all the more intense as the SW emission point is toroidally nearer to the sheath walls. A limit formula is given for a source infinitely close to the sheaths. The decay of sheath RF voltages with the sheath/source parallel distance is quantified as a function of two characteristic SW evanescence lengths. Decay lengths are smaller than antenna parallel extensions. The sheath RF voltages at an IC antenna side limiter are therefore mainly sensitive to SW emission near this limiter, as recent observations suggest. Toroidal proximity effects could also explain why sheath oscillations persist with antisymmetric strap toroidal phasing, despite the parallel anti-symmetry of the radiated field map. They could also justify current attempts at reducing the RF fields induced near antenna boxes to attenuate sheath oscillations in their vicinity.

  7. Effect of driving voltages in dual capacitively coupled radio frequency plasma: A study by nonlinear global model

    NASA Astrophysics Data System (ADS)

    Bora, B.

    2015-10-01

    On the basis of nonlinear global model, a dual frequency capacitively coupled radio frequency plasma driven by 13.56 MHz and 27.12 MHz has been studied to investigate the influences of driving voltages on the generation of dc self-bias and plasma heating. Fluid equations for the ions inside the plasma sheath have been considered to determine the voltage-charge relations of the plasma sheath. Geometrically symmetric as well as asymmetric cases with finite geometrical asymmetry of 1.2 (ratio of electrodes area) have been considered to make the study more reasonable to experiment. The electrical asymmetry effect (EAE) and finite geometrical asymmetry is found to work differently in controlling the dc self-bias. The amount of EAE has been primarily controlled by the phase angle between the two consecutive harmonics waveforms. The incorporation of the finite geometrical asymmetry in the calculations shift the dc self-bias towards negative polarity direction while increasing the amount of EAE is found to increase the dc self-bias in either direction. For phase angle between the two waveforms ϕ = 0 and ϕ = π/2, the amount of EAE increases significantly with increasing the low frequency voltage, whereas no such increase in the amount of EAE is found with increasing high frequency voltage. In contrast to the geometrically symmetric case, where the variation of the dc self-bias with driving voltages for phase angle ϕ = 0 and π/2 are just opposite in polarity, the variation for the geometrically asymmetric case is different for ϕ = 0 and π/2. In asymmetric case, for ϕ = 0, the dc self-bias increases towards the negative direction with increasing both the low and high frequency voltages, but for the ϕ = π/2, the dc-self bias is increased towards positive direction with increasing low frequency voltage while dc self-bias increases towards negative direction with increasing high frequency voltage.

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

    NASA Technical Reports Server (NTRS)

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

    1982-01-01

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

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

    SciTech Connect

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

    2015-06-15

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

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

    PubMed Central

    Lee, Hyung-Min; Ghovanloo, Maysam

    2014-01-01

    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-μm 3M2P std. CMOS process, occupying 0.144 mm2 of chip area. With 1.46 V peak AC input at 13.56 MHz, the active voltage doubler provides 2.4 V DC output across a 1 kΩ 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

  11. Optimization of energy harvesting efficiency of an oscillating hydrofoil: Sinusoidal and Non-sinusoidal trajectories

    NASA Astrophysics Data System (ADS)

    Miller, Michael; Strom, Ben; Breuer, Kenneth; Mandre, Shreyas

    2014-11-01

    We determine the feasibility of applying optimization algorithms to an oscillating hydrofoil's motion trajectory to determine maximum efficiency of energy capture. Optimization is performed using the Nelder-Meade downhill simplex method. The objective function is the energy captured measured experimentally in run-time with an oscillating hydrofoil capable of measuring mechanical energy capture in a laboratory flume. For sinusoidal trajectories, optimization is performed over pitch and heave amplitudes as well as frequency; this system is shown to be capable of optimization in run-time. The optimum efficiency of 30% is found for a pitch amplitude of 70°, a heave amplitude of 0.8* chord and a dimensionless frequency of 0.13. To treat non-sinusoidal trajectories, we expand them in a truncated Fourier series and consider the coefficients of this series as variables for optimization. The sinusoidal case is simply an extreme case of such a truncated Fourier series, with only one term in the series retained. We present a systematic method for optimization over general non-sinusoidal trajectories by including more and more terms in the Fourier series.

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

    NASA Astrophysics Data System (ADS)

    Hunter, Daniel S.

    1990-03-01

    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.

  13. Force Sensor Characterization Under Sinusoidal Excitations

    PubMed Central

    Medina, Nieves; de Vicente, Jesús

    2014-01-01

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

  14. The Retinal Response to Sinusoidal Electrical Stimulation.

    PubMed

    Twyford, Perry; Fried, Shelley

    2016-04-01

    Rectangular electrical pulses are the primary stimulus waveform used in retinal prosthetics as well as many other neural stimulation applications. Unfortunately, the utility of pulsatile stimuli is limited by the inability to avoid the activation of passing axons, which can result in the distortion of the spatial patterns of elicited neural activity. Because avoiding axons would likely improve clinical outcomes, the examination of alternate stimulus waveforms is warranted. Here, we studied the response of rabbit retinal ganglion cells (RGCs) to sinusoidal electrical stimulation applied at frequencies of 5, 10, 25, and 100 Hz. Targeted RGCs were restricted to 4 common types: OFF-Brisk Transient, OFF-Sustained, ON-Brisk Transient, and ON-Sustained. Interestingly, response patterns varied between different types; the most notable difference was the relatively weak response of ON-Sustained cells to low frequencies. Calculation of total spike counts per trial revealed that lower frequencies are more charge efficient than high frequencies. Finally, experiments utilizing synaptic blockers revealed that 5 and 10 Hz activate photoreceptors while 25 and 100 Hz activate RGCs. Taken together, our results suggest that while sinusoidal electrical stimulation may provide a useful research tool, its clinical utility may be limited. PMID:25850091

  15. Lightning-induced voltages caused by lighting strike to tall objects considering the effect of frequency dependent soil

    NASA Astrophysics Data System (ADS)

    Zhang, Qilin; Chen, Yuan; Hou, Wenhao

    2015-10-01

    In this paper we have analyzed the effect of frequency dependent soil (FDS) on the lightning-induced voltages caused by lightning subsequent return stroke for strike to tall objects ranging from 100 m to 300 m. It is found that the effect of FDS on the induced voltages peak can be approximately ignored when the low frequency conductivity (LFC) is equal to or larger than 0.01 S/m, and with the decrease of LFC, the effect of FDS on the lightning induced voltages is more obvious. Compared with the constant LFC, the induced voltage peak becomes less for FDS. For example, for a constant LFC of 0.001 S/m, the ratio of the induced voltages peak value for FDS to that for LFC is 83.2% at the line center and 66.8% at the line end for strike to 300-m-tall object, respectively. By using the decomposition method, we divide the lightning induced voltages into two components named by the incident induced waves (Vi) related with the vertical field and scattered induced waves (Vs) related with horizontal field, and it is found that FDS results into a less initial peak of tangential horizontal field along the overhead line and further results into a less induced voltage. Also, compared FDS with LFC, the FDS reduces the disparity of lightning induced voltages caused by different tall objects. For example, for the constant LFC, the induced voltage peak for strike to 300-m-tall object is 1.69 times larger than that for strike to 50-m-tall object. However, for the case of FDS, the corresponding ratio is about 1.2.

  16. Effect of driving voltages in dual capacitively coupled radio frequency plasma: A study by nonlinear global model

    SciTech Connect

    Bora, B.

    2015-10-15

    On the basis of nonlinear global model, a dual frequency capacitively coupled radio frequency plasma driven by 13.56 MHz and 27.12 MHz has been studied to investigate the influences of driving voltages on the generation of dc self-bias and plasma heating. Fluid equations for the ions inside the plasma sheath have been considered to determine the voltage-charge relations of the plasma sheath. Geometrically symmetric as well as asymmetric cases with finite geometrical asymmetry of 1.2 (ratio of electrodes area) have been considered to make the study more reasonable to experiment. The electrical asymmetry effect (EAE) and finite geometrical asymmetry is found to work differently in controlling the dc self-bias. The amount of EAE has been primarily controlled by the phase angle between the two consecutive harmonics waveforms. The incorporation of the finite geometrical asymmetry in the calculations shift the dc self-bias towards negative polarity direction while increasing the amount of EAE is found to increase the dc self-bias in either direction. For phase angle between the two waveforms ϕ = 0 and ϕ = π/2, the amount of EAE increases significantly with increasing the low frequency voltage, whereas no such increase in the amount of EAE is found with increasing high frequency voltage. In contrast to the geometrically symmetric case, where the variation of the dc self-bias with driving voltages for phase angle ϕ = 0 and π/2 are just opposite in polarity, the variation for the geometrically asymmetric case is different for ϕ = 0 and π/2. In asymmetric case, for ϕ = 0, the dc self-bias increases towards the negative direction with increasing both the low and high frequency voltages, but for the ϕ = π/2, the dc-self bias is increased towards positive direction with increasing low frequency voltage while dc self-bias increases towards negative direction with increasing high frequency voltage.

  17. Cell property determination from the acoustic microscope generated voltage versus frequency curves.

    PubMed Central

    Kundu, T; Bereiter-Hahn, J; Karl, I

    2000-01-01

    Among the methods for the determination of mechanical properties of living cells acoustic microscopy provides some extraordinary advantages. It is relatively fast, of excellent spatial resolution and of minimal invasiveness. Sound velocity is a measure of the stiffness or Young's modulus of the cell. Attenuation of cytoplasm is a measure of supramolecular interactions. These parameters are of crucial interest for studies of cell motility, volume regulations and to establish the functional role of the various elements of the cytoskeleton. Using a phase and amplitude sensitive modulation of a scanning acoustic microscope (Hillman et al., 1994, J. Alloys Compounds. 211/212:625-627) longitudinal wave speed, attenuation and thickness profile of a biological cell are obtained from the voltage versus frequency or V(f) curves. A series of pictures, for instance in the frequency range 980-1100 MHz with an increment of 20 MHz, allows the experimental generation of V(f) curves for each pixel while keeping the lens-specimen distance unchanged. Both amplitude and phase values of the V(f) curves are used for obtaining the cell properties and the cell thickness profile. The theoretical analysis shows that the thin liquid layer, between the cell and the substrate, has a strong influence on the reflection coefficient and should not be ignored during the analysis. Cell properties, cell profile and the thickness of the thin liquid layer are obtained from the V(f) curves by the simplex inversion algorithm. The main advantages of this new method are that imaging can be done near the focal plane, therefore an optimal signal to noise ratio is achieved, no interference with Rayleigh waves occurs, and the method requires only an approximate estimate of the material properties of the solid substratum where the cells are growing on. PMID:10777725

  18. A MEMS Interface IC With Low-Power and Wide-Range Frequency-to-Voltage Converter for Biomedical Applications.

    PubMed

    Arefin, Md Shamsul; Redoute, Jean-Michel; Yuce, Mehmet Rasit

    2016-04-01

    This paper presents an interface circuit for capacitive and inductive MEMS biosensors using an oscillator and a charge pump based frequency-to-voltage converter. Frequency modulation using a differential crossed coupled oscillator is adopted to sense capacitive and inductive changes. The frequency-to-voltage converter is designed with a negative feedback system and external controlling parameters to adjust the sensitivity, dynamic range, and nominal point for the measurement. The sensitivity of the frequency-to-voltage converter is from 13.28 to 35.96 mV/MHz depending on external voltage and charging current. The sensitivity ranges of the capacitive and inductive interface circuit are 17.08 to 54.4 mV/pF and 32.11 to 82.88 mV/mH, respectively. A capacitive MEMS based pH sensor is also connected with the interface circuit to measure the high acidic gastric acid throughout the digestive tract. The sensitivity for pH from 1 to 3 is 191.4 mV/pH with 550 μ V pp noise. The readout circuit is designed and fabricated using the UMC 0.18 μm CMOS technology. It occupies an area of 0.18 mm (2) and consumes 11.8 mW. PMID:26954843

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

    NASA Astrophysics Data System (ADS)

    Chang, Hung-wen; Hsu, Cheng-che

    2012-06-01

    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.

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

    PubMed

    Bassi, Welson

    2014-01-01

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

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

    DOEpatents

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

    1994-06-28

    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.

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

    DOEpatents

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

    1994-01-01

    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.

  3. High frequency capacitance-voltage characteristics of thermally grown SiO2 films on beta-SiC

    NASA Technical Reports Server (NTRS)

    Tang, S. M.; Berry, W. B.; Kwor, R.; Zeller, M. V.; Matus, L. G.

    1990-01-01

    Silicon dioxide films grown under dry and wet oxidation environment on beta-SiC films have been studied. The beta-SiC films had been heteroepitaxially grown on both on-axis and 2-deg off-axis (001) Si substrates. Capacitance-voltage and conductance-voltage characteristics of metal-oxide-semiconductor structures were measured in a frequency range of 10 kHz to 1 MHz. From these measurements, the interface trap density and the effective fixed oxide charge density were observed to be generally lower for off-axis samples.

  4. Systematic Review of the Exposure Assessment and Epidemiology of High-Frequency Voltage Transients.

    PubMed

    de Vocht, Frank; Olsen, Robert G

    2016-01-01

    Conclusions of epidemiological studies describing adverse health effects as a result of exposure to electromagnetic fields are not unanimous and often contradictory. It has been proposed that an explanation could be that high-frequency voltage transients [dirty electricity (DE)] which are superimposed on 50/60-Hz fields, but are generally not measured, are the real causal agent. DE has been linked to many different health and wellbeing effects, and on the basis of this, an industry selling measurement and filtering equipment is growing. We reviewed the available peer-reviewed evidence for DE as a causal agent for adverse human health effects. A literature search was performed in the Cochrane Library, PubMed, Web of Science, Google Scholar, and additional publications were obtained from reference lists and from the gray literature. This search resulted in 25 publications; 16 included primary epidemiological and/or exposure data. All studies were reviewed by both authors independently, and including a re-review of studies included in a review of data available up to July 31, 2009 by one of the authors. DE has been measured differently in different studies and comparison data are not available. There is no evidence for 50 Graham/Stetzer (GS) units as a safety threshold being anything more than arbitrary. The epidemiological evidence on human health effects of DE is primarily based on, often re-used, case descriptions. Quantitative evidence relies on self-reporting in non-blinded interventions, ecological associations, and one cross-sectional cohort study of cancer risk, which does not point to DE as the causal agent. The available evidence for DE as an exposure affecting human health at present does not stand up to scientific scrutiny. PMID:27066469

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

    PubMed Central

    2012-01-01

    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

  6. Systematic Review of the Exposure Assessment and Epidemiology of High-Frequency Voltage Transients

    PubMed Central

    de Vocht, Frank; Olsen, Robert G.

    2016-01-01

    Conclusions of epidemiological studies describing adverse health effects as a result of exposure to electromagnetic fields are not unanimous and often contradictory. It has been proposed that an explanation could be that high-frequency voltage transients [dirty electricity (DE)] which are superimposed on 50/60-Hz fields, but are generally not measured, are the real causal agent. DE has been linked to many different health and wellbeing effects, and on the basis of this, an industry selling measurement and filtering equipment is growing. We reviewed the available peer-reviewed evidence for DE as a causal agent for adverse human health effects. A literature search was performed in the Cochrane Library, PubMed, Web of Science, Google Scholar, and additional publications were obtained from reference lists and from the gray literature. This search resulted in 25 publications; 16 included primary epidemiological and/or exposure data. All studies were reviewed by both authors independently, and including a re-review of studies included in a review of data available up to July 31, 2009 by one of the authors. DE has been measured differently in different studies and comparison data are not available. There is no evidence for 50 Graham/Stetzer (GS) units as a safety threshold being anything more than arbitrary. The epidemiological evidence on human health effects of DE is primarily based on, often re-used, case descriptions. Quantitative evidence relies on self-reporting in non-blinded interventions, ecological associations, and one cross-sectional cohort study of cancer risk, which does not point to DE as the causal agent. The available evidence for DE as an exposure affecting human health at present does not stand up to scientific scrutiny. PMID:27066469

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

    PubMed

    Asgarifar, Hajarossadat; Oloyede, Adekunle; Zare, Firuz

    2014-04-01

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

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

    PubMed Central

    Asgarifar, Hajarossadat; Oloyede, Adekunle; Zare, Firuz

    2014-01-01

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

  9. Complex heterodyne for undersampled chirped sinusoidal signals.

    PubMed

    Niebauer, T M; Schiel, A; van Westrum, D

    2006-11-10

    We describe a method for analyzing frequency-chirped sinusoidal signals using a complex heterodyne, sometimes also known as complex demodulation on the digitized waveform. This method allows one to use prior knowledge of the signal to reduce the effective bandwidth of the signal. The method can be used to extract a frequency-chirped signal even when it is sampled well below the Nyquist criterion. Accordingly, the method facilitates the use of less-expensive data acquisition and signal processing hardware than has traditionally been used for these applications. This technique is particularly useful for high-precision (parts in 10(9)) interferometer applications in which there exists a differential acceleration between the two arms (commonly found in absolute gravity meters or gradiometers). PMID:17068577

  10. Complex heterodyne for undersampled chirped sinusoidal signals

    NASA Astrophysics Data System (ADS)

    Niebauer, T. M.; Schiel, A.; van Westrum, D.

    2006-11-01

    We describe a method for analyzing frequency-chirped sinusoidal signals using a complex heterodyne, sometimes also known as complex demodulation on the digitized waveform. This method allows one to use prior knowledge of the signal to reduce the effective bandwidth of the signal. The method can be used to extract a frequency-chirped signal even when it is sampled well below the Nyquist criterion. Accordingly, the method facilitates the use of less-expensive data acquisition and signal processing hardware than has traditionally been used for these applications. This technique is particularly useful for high-precision (parts in 109) interferometer applications in which there exists a differential acceleration between the two arms (commonly found in absolute gravity meters or gradiometers).

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

    NASA Astrophysics Data System (ADS)

    Rowihal, Said Soliman

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

  12. Experimental studies on power frequency breakdown voltage of CF3I/N2 mixed gas under different electric fields

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaoxing; Xiao, Song; Han, Yefei; Cressault, Yann

    2016-02-01

    To verify the feasibility of replacing SF6 by CF3I/N2, we compared their power frequency breakdown performance with the influence of gas pressure, mixing ratio, and electric field utilization coefficient. Under different electric fields and mixing ratios, the power frequency breakdown voltage of CF3I/N2 increases linearly along with gas pressure. Besides, with the rise of the electric field utilization coefficient, the linear growth rate of breakdown voltage along with gas pressure gradually rises. The sensitivity of pure CF3I to electric field is particularly high and can be improved by the addition of N2. The mixture 30% CF3I/70% N2 at 0.3 MPa could replace pure SF6 in equipment requiring a low insulation, but the gas pressure or the content of CF3I need to be increased for higher insulation requirements.

  13. Extremely-low-frequency magnetic field exposure of children at schools near high voltage transmission lines.

    PubMed

    Li, Chung-Yi; Sung, Fung-Chang; Chen, Fu-Li; Lee, Pei-Chen; Silva, Michael; Mezei, Gabor

    2007-04-15

    Many epidemiological studies have investigated residential exposure to extremely-low-frequency magnetic field (ELF-MF) for children, but exposure at schools where children may stay up to 8 h every weekday was rarely considered. Between March and June 2004, we carried out a field study in Taipei City and County of northern Taiwan to explore ELF-MF exposure pattern among children at schools with high voltage transmission lines (HVTL) running through the campuses. One hundred and one children attending 14 schools with nearby HVTL (exposed group) and 123 children of 18 schools at least 100 m away from HVTL (unexposed group) were monitored for 24-hour personal ELF-MF exposure. Selected classrooms and playgrounds within the buffer regions (i.e., within 30 m of HVTL) and those away from the buffer regions were also assessed, using spot measurements, to determine the extent to which HVTL may contribute to the environmental exposure on campuses. Results show that the two groups didn't differ significantly for both mean exposure and proportion of exposure greater than 0.4 micro-Tesla (microT) estimated for 24 h. However, we noted that 17.8% of the exposed children had a personal mean exposure greater than 0.4 microT during school hours, significantly (p=0.011) higher than that (6.5%) estimated for the unexposed children. An even higher percentage (27.3%) was observed for 11 students with their classrooms intersecting the buffer regions. Playgrounds near buffer regions showed a significantly higher ELF-MF than the other areas of the exposed schools (0.70 vs 0.18 microT, p=0.043). The study demonstrates a wide range of exposures to ELF-MF among school children at campuses adjacent to HVTL. Children attending the exposed schools may have a higher chance of experiencing a mean exposure greater than 0.4 microT during school hours. PMID:17316772

  14. Current-voltage characteristics and low-frequency noise in carbon nanotube thin films with disordered networks

    NASA Astrophysics Data System (ADS)

    Avetisyan, Vardan; Makaryan, Taron; Chen, Gugang; Harutyunyan, Avetik; Makaryan, Armen

    2015-03-01

    Efficient exploitation of carbon nanotubes in electronics requires knowledge of their current-voltage (I-V) and noise parameters. We studied the dependence of these parameters for two single walled carbon nanotube (SWNT) thin films with different thicknesses in the voltage range of 0-130 V and frequency range of 0-160 kHz. Hidden nonlinear I-V dependence in the range of 10 to 120 V was detected by carrying out transient measurements with minimized heat-induced effect. The thinner film demonstrates enhanced non-linear characteristics, which suggests its potential application in pulse-pumped THz generation. We also distinct a 1/f and a shot type noise in the low-frequency range up to 20 kHz and in the frequency range up to 160 kHz, respectively. Based on the noise dispersion dependence on applied voltage and film thicknesses we attribute its origin to charge carrier tunneling through tube-tube contacts. These findings can be valuable for controlling the noise for efficient vertical downscaling of conventional electronics systems. Second Affiliation: Instutute of Radiophysics and Electronics, 0203 Ashtarak, Armenia.

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

    NASA Astrophysics Data System (ADS)

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

    2013-05-01

    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.

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

    NASA Technical Reports Server (NTRS)

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

    1977-01-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

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

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

    NASA Technical Reports Server (NTRS)

    Riaz, M.

    1970-01-01

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

  19. The piezoelectronic stress transduction switch for very large-scale integration, low voltage sensor computation, and radio frequency applications

    NASA Astrophysics Data System (ADS)

    Magdǎu, I.-B.; Liu, X.-H.; Kuroda, M. A.; Shaw, T. M.; Crain, J.; Solomon, P. M.; Newns, D. M.; Martyna, G. J.

    2015-08-01

    The piezoelectronic transduction switch is a device with potential as a post-CMOS transistor due to its predicted multi-GHz, low voltage performance on the VLSI-scale. However, the operating principle of the switch has wider applicability. We use theory and simulation to optimize the device across a wide range of length scales and application spaces and to understand the physics underlying its behavior. We show that the four-terminal VLSI-scale switch can operate at a line voltage of 115 mV while as a low voltage-large area device, ≈200 mV operation at clock speeds of ≈2 GHz can be achieved with a desirable 104 On/Off ratio—ideal for on-board computing in sensors. At yet larger scales, the device is predicted to operate as a fast (≈250 ps) radio frequency (RF) switch exhibiting high cyclability, low On resistance and low Off capacitance, resulting in a robust switch with a RF figure of merit of ≈4 fs. These performance benchmarks cannot be approached with CMOS which has reached fundamental limits. In detail, a combination of finite element modeling and ab initio calculations enables prediction of switching voltages for a given design. A multivariate search method then establishes a set of physics-based design rules, discovering the key factors for each application. The results demonstrate that the piezoelectronic transduction switch can offer fast, low power applications spanning several domains of the information technology infrastructure.

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

    NASA Astrophysics Data System (ADS)

    Yingping, Chen; Zhiqian, Li

    2015-05-01

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

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

    SciTech Connect

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

    2013-11-21

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

  2. Strong ionization asymmetry in a geometrically symmetric radio frequency capacitively coupled plasma induced by sawtooth voltage waveforms.

    PubMed

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

    2015-03-27

    The ionization dynamics in geometrically symmetric parallel plate capacitively coupled plasmas driven by radio frequency tailored voltage waveforms is investigated using phase resolved optical emission spectroscopy (PROES) and particle-in-cell (PIC) simulations. Temporally asymmetric waveforms induce spatial asymmetries and offer control of the spatiotemporal dynamics of electron heating and associated ionization structures. Sawtooth waveforms with different rise and fall rates are employed using truncated Fourier series approximations of an ideal sawtooth. Experimental PROES results obtained in argon plasmas are compared with PIC simulations, showing excellent agreement. With waveforms comprising a fast voltage drop followed by a slower rise, the faster sheath expansion in front of the powered electrode causes strongly enhanced ionization in this region. The complementary waveform causes an analogous effect in front of the grounded electrode. PMID:25860749

  3. Flexible low-voltage organic integrated circuits with megahertz switching frequencies (Presentation Recording)

    NASA Astrophysics Data System (ADS)

    Zschieschang, Ute; Takimiya, Kazuo; Zaki, Tarek; Letzkus, Florian; Richter, Harald; Burghartz, Joachim N.; Klauk, Hagen

    2015-09-01

    A process for the fabrication of integrated circuits based on bottom-gate, top-contact organic thin-film transistors (TFTs) with channel lengths as short as 1 µm on flexible plastic substrates has been developed. In this process, all TFT layers (gate electrodes, organic semiconductors, source/drain contacts) are patterned with the help of high-resolution silicon stencil masks, thus eliminating the need for subtractive patterning and avoiding the exposure of the organic semiconductors to potentially harmful organic solvents or resists. The TFTs employ a low-temperature-processed gate dielectric that is sufficiently thin to allow the TFTs and circuits to operate with voltages of about 3 V. Using the vacuum-deposited small-molecule organic semiconductor 2,9-didecyl-dinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene (C10 DNTT), TFTs with an effective field-effect mobility of 1.2 cm2/Vs, an on/off current ratio of 107, a width-normalized transconductance of 1.2 S/m (with a standard deviation of 6%), and a signal propagation delay (measured in 11-stage ring oscillators) of 420 nsec per stage at a supply voltage of 3 V have been obtained. To our knowledge, this is the first time that megahertz operation has been achieved in flexible organic transistors at supply voltages of less than 10 V. In addition to flexible ring oscillators, we have also demonstrated a 6-bit digital-to-analog converter (DAC) in a binary-weighted current-steering architecture, based on TFTs with a channel length of 4 µm and fabricated on a glass substrate. This DAC has a supply voltage of 3.3 V, a circuit area of 2.6 × 4.6 mm2, and a maximum sampling rate of 100 kS/s.

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

    DOEpatents

    Miller, Paul A.; Kamon, Mattan

    1994-01-01

    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.

  5. Cosmology and the Sinusoidal Potential

    NASA Astrophysics Data System (ADS)

    Bartlett, David F.

    2006-06-01

    The nature of dark matter (and dark energy) remains a mystery. An alternative is being explored by several scientists: changing Newton's (and Einstein's) field equations. The sinusoidal potential is the latest attempt[1]. Here the gravitational law is alternately attractive and repulsive:φ = -GM cos(kor)/r, where λo=2π/ko = 1/20 of the distance from the sun to the center of the Milky Way. The proposal accommodates several structural features of the Milky Way including, paradoxically, its spiral shape and flat rotation curve. The sinusoidal potential's unique feature is strong galactic tidal forces (dg/dr). These may explain why the new planetoid Sedna is securely between the Kuiper Belt and the Oort cloud and why distant comets are more influenced by galactic tides that are in the r, rather than the z-direction.At this meeting I discuss the consequences of the sinusoidal potential for cosmology. Here the alternation of attraction and repulsion gives (i) an open universe, and (ii) gravitational lensing which is usually weak, but occasionally very strong. An open universe is one that, asymptotically, has a size R which varies directly as time t. The open universe conflicts both with the old Einstein-deSitter model (R α t2/3} and the new accelerating one. The evidence for an accelerating universe decisively rejects the Einstein-deSitter model. The rejection of an open (or empty) universe is less secure. This rejection is influenced by the different ways the groups studying the brightness of supernovae use the HST. Surprising additional inputs include neutrino masses, the equivalence principle, LSB galaxies, and "over-luminous" Sn1a. I thank Mostafa Jon Dadras and Patrick Motl for early help and John Cumalat for continual support. [1] D.F. Bartlett, "Analogies between electricity and gravity", Metrologia 41, S115-S124 (2004).

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

    NASA Astrophysics Data System (ADS)

    Hur, Jin-Suk; Roh, Myung-Sub

    2014-02-01

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

  7. High frequency capacitance-voltage technique for the extraction of interface trap density of the heterojunction capacitor: Terman's method revised

    NASA Astrophysics Data System (ADS)

    Deen, David A.; Champlain, James G.

    2011-08-01

    In a multi-layer heterojunction system, the interface responsible for trap charging is spatially displaced from the two-dimensional charge gas, in contrast to the typical SiO2/Si capacitor. This displacement causes the effective trap capacitance to occur in a different configuration than that of the SiO2/Si system that Terman originally considered. The adaptation of Terman's high frequency capacitance-voltage method for interface trap density extraction is developed for the heterojunction multi-layer capacitor.

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

    SciTech Connect

    Hur, Jin-Suk; Roh, Myung- Sub

    2014-02-12

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

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

    SciTech Connect

    Wessendorf, K.O.

    1996-08-01

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

  10. Low-voltage polyphasic circuits

    NASA Astrophysics Data System (ADS)

    Baird, William H.; Jaynes, Michael L.

    2010-05-01

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

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

    PubMed Central

    Yıldız, D. E.; Dökme, İ.

    2011-01-01

    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 (ɛ′) and loss tangent (tan δ) characteristics have a peak at each frequency. The values of ɛ′ increase with decreasing frequency and tend to be frequency independent in the negative voltage region. However, the values of the dielectric loss (ɛ″) increase with decreasing frequency at each voltage. In contrast, ɛ′ and ɛ″ are almost found to decrease, and the ac electrical conductivity (σac) 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

  12. 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)

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

    2014-10-01

    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.

  13. Design of a pulsewidth-modulated resonant converter for a high-output-voltage power supply

    NASA Astrophysics Data System (ADS)

    Turnbull, Fred G.; Tompkins, Russell E.

    1987-12-01

    The design and fabrication of a parallel resonant converter circuit and a high-frequency step-up transformer used to supply an adjustable dc voltage to a load is described. The 500-W system is operated from 115/230 V single-phase 60Hz power, which is rectified and filtered to form a 310-V dc link. A two-transistor half-bridge circuit operating at a fixed frequency above the ciruits resonant frequency converts the dc voltage to an ac voltage at approximately 20 kHx. This high-frequency voltage is transformed with a low-capacitance oil-impregnated ferrite transformer. The output voltage is rectified to form a dc voltage with a maximum value of 90-kV peak. The output voltage is adjustable using pulsewidth modulation of the conduction time of the two transistors in the power circuit. The energy stored in the resonant circuit provides a sinusoidal transformer voltage at fixed frequency over a wide range of control. The system is provided with a closed-loop peak-voltage regulator and an on-off capability from the control electronics. The transformer is designed for a specific value of inductance and capacitance to operate at the desired resonant frequency and characteristic impedance.

  14. Electrolyte-Gated Graphene Ambipolar Frequency Multipliers for Biochemical Sensing.

    PubMed

    Fu, Wangyang; Feng, Lingyan; Mayer, Dirk; Panaitov, Gregory; Kireev, Dmitry; Offenhäusser, Andreas; Krause, Hans-Joachim

    2016-04-13

    In this Letter, the ambipolar properties of an electrolyte-gated graphene field-effect transistor (GFET) have been explored to fabricate frequency-doubling biochemical sensor devices. By biasing the ambipolar GFETs in a common-source configuration, an input sinusoidal voltage at frequency f applied to the electrolyte gate can be rectified to a sinusoidal wave at frequency 2f at the drain electrode. The extraordinary high carrier mobility of graphene and the strong electrolyte gate coupling provide the graphene ambipolar frequency doubler an unprecedented unity gain, as well as a detection limit of ∼4 pM for 11-mer single strand DNA molecules in 1 mM PBS buffer solution. Combined with an improved drift characteristics and an enhanced low-frequency 1/f noise performance by sampling at doubled frequency, this good detection limit suggests the graphene ambipolar frequency doubler a highly promising biochemical sensing platform. PMID:26928906

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

    PubMed

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

    2011-12-01

    The ability to elicit visual percepts through electrical stimulation of the retina has prompted numerous investigations examining the feasibility of restoring sight to the blind with retinal implants. The therapeutic efficacy of these devices will be strongly influenced by their ability to elicit neural responses that approximate those of normal vision. Retinal ganglion cells (RGCs) can fire spikes at frequencies greater than 200 Hz when driven by light. However, several studies using isolated retinas have found a decline in RGC spiking response rate when these cells were stimulated at greater than 50 Hz. It is possible that the mechanism responsible for this decline also contributes to the frequency-dependent 'fading' of electrically evoked percepts recently reported in human patients. Using whole-cell patch clamp recordings of rabbit RGCs, we investigated the causes for the spiking response depression during direct subretinal stimulation of these cells at 50-200 Hz. The response depression was not caused by inhibition arising from the retinal network but, instead, by a stimulus-frequency-dependent decline of RGC voltage-gated sodium current. Under identical experimental conditions, however, RGCs were able to spike at high frequency when driven by light stimuli and intracellular depolarization. Based on these observations, we demonstrated a technique to prevent the spiking response depression. PMID:22027396

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

    NASA Astrophysics Data System (ADS)

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

    2011-10-01

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

  17. High-frequency trigger generators for CuBr-laser high voltage pumping source

    NASA Astrophysics Data System (ADS)

    Torgaev, S.; Kozhemyak, O.; Yaroslavtsev, E.; Trigub, M.; Musorov, I.; Chertikhina, D.

    2016-04-01

    In this paper the circuits of high frequency trigger generators of pulses of the nanosecond duration are presented. A detailed study of a generator based on the avalanche transistor with the use of a coaxial cable instead of a capacitor is described. This circuit showed advanced characteristics of the output pulses. A circuit of a generator built on high-speed digital components is also considered. The basic advantages and disadvantages of both generators are presented in this paper.

  18. Propulsion by sinusoidal locomotion: A motion inspired by Caenorhabditis elegans

    NASA Astrophysics Data System (ADS)

    Ulrich, Xialing

    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.

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

    PubMed

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

    2008-09-01

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

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

    SciTech Connect

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

    2008-09-15

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

  1. Sinusoidal analysis of electroretinogram of squid and octopus.

    PubMed

    Hartline, P H; Lange, G D

    1977-01-01

    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

  2. Nonlinear dynamics control in single-phase inverter with sinusoidal pulse-width modulation

    NASA Astrophysics Data System (ADS)

    Andriyanov, A. I.; Mikhal'tsov, D. Yu

    2016-04-01

    A variant of technical implementation of the control system of a single-phase voltage inverter with sinusoidal pulse-width modulation, based on target-oriented control, which ensures the desired nonlinear dynamic properties of the system, is proposed. The control system under discussion solves the problem of providing a sinusoidal output voltage of the inverter when changing its parameters in a wide range, accompanied by bifurcations. This eliminates unwanted dynamic modes without parametric synthesis of the system. The target-oriented control for managing the dynamics of nonlinear systems with sinusoidal pulse-width modulation is used for the first time and gives a number of advantages compared to other known methods.

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

    SciTech Connect

    Garrison, Sean

    2009-05-21

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

  5. Self-mixing interferometer based on sinusoidal phase modulating technique

    NASA Astrophysics Data System (ADS)

    Guo, Dongmei; Wang, Ming; Tan, Suqing

    2005-03-01

    A new self-mixing interferometry based on sinusoidal phase modulating technique is presented. Self-mixing interference occurs in the laser cavity by reflecting the light from a mirror-like target in front of the laser. Sinusoidal phase modulation of the beam is obtained by an electro-optic modulator (EOM) in the external cavity. The phase of the interference signal is calculated by Fourier analysis method. The interferometer is applied to measure the displacement of a high-precision commercial PZT with an accuracy of <10nm. The measurement range of the system mainly depends on the maximum operating frequency of EOM and the maximum sampling rate of A/D converter.

  6. Self-mixing interferometer based on sinusoidal phase modulating technique.

    PubMed

    Guo, Dongmei; Wang, Ming; Tan, Suqing

    2005-03-01

    A new self-mixing interferometry based on sinusoidal phase modulating technique is presented. Self-mixing interference occurs in the laser cavity by reflecting the light from a mirror-like target in front of the laser. Sinusoidal phase modulation of the beam is obtained by an electro-optic modulator (EOM) in the external cavity. The phase of the interference signal is calculated by Fourier analysis method. The interferometer is applied to measure the displacement of a high-precision commercial PZT with an accuracy of <10nm. The measurement range of the system mainly depends on the maximum operating frequency of EOM and the maximum sampling rate of A/D converter. PMID:19495029

  7. Alternating frequency to increase the response to stimulation from medium voltage electrical stimulation and the effect on objective meat quality.

    PubMed

    Pearce, K L; Hopkins, D L; Williams, A; Jacob, R H; Pethick, D W; Phillips, J K

    2009-01-01

    The use of alternating frequencies during stimulation can increase stimulation response of a medium voltage electrical stimulation unit (MVS) by increasing the rate of pH decline. Various combinations of frequency modulation were tested in experiment 1 to determine the treatment resulting in the greatest stimulation response; the lowest initial pH, fastest rate of pH decline, highest temperature at pH 6 and the highest number of carcasses with a pH of 6 by 25(o)C and the treatment achieving the highest number of carcasses in the pH temp window (temperature at pH 6 between 18-25(o)C). The objective meat quality of these treatments compared to an unstimulated treatment was tested in experiment 2. Modulating the frequency (Hz) across the 6 segmented electrodes of the MVS by 10, 15, 25, 10, 15, 25Hz (Treatment 6, using a pulse width: 2.5ms, current: 1A) resulted in the greatest stimulation response. This treatment may be suitable for abattoirs that hot bone sheepmeat and require fast pH declines to ensure minimal cold shortening of meat. However, this treatment did not result in the tenderer meat despite the higher stimulation response. This treatment may have induced a greater number of contractions overall and therefore a greater pH decline response but resulted in less myofibrillar disruption compared to the other treatments due to a concomitant decreased force of contraction thus reducing potential tenderisation. Maintaining a constant frequency of 15Hz (Treatment 1; pulse width: 2.5ms, current: 1A) resulted in a higher number of carcasses in the pH temp window required (temperature at pH 6 between 18-25(o)C) in part A (P<0.05) and in addition to the higher tenderness levels this treatment may be more appropriate to satisfy the overall demands of abattoirs using these systems. This paper has also demonstrated electrical stimulation results in tenderer meat compared to unstimulated meat even after 30d of ageing (2.53±0.4 compared to 2.85±0.1 for the loin (M. longissimus thoracis et lumborum) (P<0.01) possibly due to a protective benefit of stimulation on meat tenderness. Overall, no detrimental effects of modulating frequency were observed on drip loss or retail colour display despite a greater rate of colour change observed with the modulated frequency treatment and the longer aged product. PMID:22063981

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

    NASA Astrophysics Data System (ADS)

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

    2009-10-01

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

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

    PubMed

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

    2003-11-01

    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

  10. Readily implemented enhanced sinusoid detection in noise

    SciTech Connect

    Lindsay, K.V.

    1992-03-05

    Significant efforts have been devoted, spanning many years, to the problem of sinusoid detection in noise. Many of these efforts have produced superb, yet complex, algorithms which may be difficult to use for a wide segment of the Digital Signal Processing (DSP) community. This paper presents a simple, easily implemented and high effective method which solves this problem. This method severely degrades non-sinusoidal noise while leaving the embedded sinusoid(s) relatively undisturbed. The algorithm, simply put, exploits the difference between the net effect of integration and differentiation of sinusoids versus the effect of these operations on random noise and other signal sequences. The cross-correlation of sine wave with its differentiated (and/or integrated) self is quite high. Conversely, the cross-reduction of a noise sequence with its differentiated (and/or integrated) self is much lower. Therefore, it is reasonable to assume that for sequences consisting of a sinusoid in noise, significant signal-to-noise-ratios (SNRs) in the correlation results are achievable using a combination of differentiation (and/or integration) and cross-correlation operations on such sequences. This technique has been applied to actual Doppler radar data, as well as to synthesized data, with excellent improvement in signal detection capability. 4 refs.

  11. One-dimensional plasma photonic crystals with sinusoidal densities

    SciTech Connect

    Qi, L. Shang, L.; Zhang, S.

    2014-01-15

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

  12. Simulation of temperature field for temperature-controlled radio frequency ablation using a hyperbolic bioheat equation and temperature-varied voltage calibration: a liver-mimicking phantom study

    NASA Astrophysics Data System (ADS)

    Zhang, Man; Zhou, Zhuhuang; Wu, Shuicai; Lin, Lan; Gao, Hongjian; Feng, Yusheng

    2015-12-01

    This study aims at improving the accuracy of temperature simulation for temperature-controlled radio frequency ablation (RFA). We proposed a new voltage-calibration method in the simulation and investigated the feasibility of a hyperbolic bioheat equation (HBE) in the RFA simulation with longer durations and higher power. A total of 40 RFA experiments was conducted in a liver-mimicking phantom. Four mathematical models with multipolar electrodes were developed by the finite element method in COMSOL software: HBE with/without voltage calibration, and the Pennes bioheat equation (PBE) with/without voltage calibration. The temperature-varied voltage calibration used in the simulation was calculated from an experimental power output and temperature-dependent resistance of liver tissue. We employed the HBE in simulation by considering the delay time ? of 16?s. First, for simulations by each kind of bioheat equation (PBE or HBE), we compared the differences between the temperature-varied voltage-calibration and the fixed-voltage values used in the simulations. Then, the comparisons were conducted between the PBE and the HBE in the simulations with temperature-varied voltage calibration. We verified the simulation results by experimental temperature measurements on nine specific points of the tissue phantom. The results showed that: (1) the proposed voltage-calibration method improved the simulation accuracy of temperature-controlled RFA for both the PBE and the HBE, and (2) for temperature-controlled RFA simulation with the temperature-varied voltage calibration, the HBE method was 0.55 C more accurate than the PBE method. The proposed temperature-varied voltage calibration may be useful in temperature field simulations of temperature-controlled RFA. Besides, the HBE may be used as an alternative in the simulation of long-duration high-power RFA.

  13. Dietary macronutrients and the aging liver sinusoidal endothelial cell.

    PubMed

    Cogger, Victoria Carroll; Mohamad, Mashani; Solon-Biet, Samantha Marie; Senior, Alistair M; Warren, Alessandra; O'Reilly, Jennifer Nicole; Tung, Bui Thanh; Svistounov, Dmitri; McMahon, Aisling Clare; Fraser, Robin; Raubenheimer, David; Holmes, Andrew J; Simpson, Stephen James; Le Couteur, David George

    2016-05-01

    Fenestrations are pores within the liver sinusoidal endothelial cells (LSECs) that line the sinusoids of the highly vascularized liver. Fenestrations facilitate the transfer of substrates between blood and hepatocytes. With pseudocapillarization of the hepatic sinusoid in old age, there is a loss of fenestrations. LSECs are uniquely exposed to gut-derived dietary and microbial substrates delivered by the portal circulation to the liver. Here we studied the effect of 25 diets varying in content of macronutrients and energy on LSEC fenestrations using the Geometric Framework method in a large cohort of mice aged 15 mo. Macronutrient distribution rather than total food or energy intake was associated with changes in fenestrations. Porosity and frequency were inversely associated with dietary fat intake, while fenestration diameter was inversely associated with protein or carbohydrate intake. Fenestrations were also linked to diet-induced changes in gut microbiome, with increased fenestrations associated with higher abundance of Firmicutes and reduced abundance of Bacteroidetes Diet-induced changes in levels of several fatty acids (C16:0, C19:0, and C20:4) were also significantly inversely associated with fenestrations, suggesting a link between dietary fat and modulation of lipid rafts in the LSECs. Diet influences fenestrations and these data reflect both the key role of the LSECs in clearing gut-derived molecules from the vascular circulation and the impact these molecules have on LSEC morphology. PMID:26921440

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

    PubMed

    Liu, Ying-Pei; Liang, Hai-Ping; Gao, Zhong-Ke

    2015-01-01

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

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

    PubMed Central

    Gao, Zhong-Ke

    2015-01-01

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

  16. Frequency and voltage dependent profile of dielectric properties, electric modulus and ac electrical conductivity in the PrBaCoO nanofiber capacitors

    NASA Astrophysics Data System (ADS)

    Demirezen, S.; Kaya, A.; Yerişkin, S. A.; Balbaşı, M.; Uslu, İ.

    In this study, praseodymium barium cobalt oxide nanofiber interfacial layer was sandwiched between Au and n-Si. Frequency and voltage dependence of ε‧, ε‧, tanδ, electric modulus (M‧ and M″) and σac of PrBaCoO nanofiber capacitor have been investigated by using impedance spectroscopy method. The obtained experimental results show that the values of ε‧, ε‧, tanδ, M‧, M″ and σac of the PrBaCoO nanofiber capacitor are strongly dependent on frequency of applied bias voltage. The values of ε‧, ε″ and tanδ show a steep decrease with increasing frequency for each forward bias voltage, whereas the values of σac and the electric modulus increase with increasing frequency. The high dispersion in ε‧ and ε″ values at low frequencies may be attributed to the Maxwell-Wagner and space charge polarization. The high values of ε‧ may be due to the interfacial effects within the material, PrBaCoO nanofibers interfacial layer and electron effect. The values of M‧ and M″ reach a maximum constant value corresponding to M∞ ≈ 1/ε∞ due to the relaxation process at high frequencies, but both the values of M‧ and M″ approach almost to zero at low frequencies. The changes in the dielectric and electrical properties with frequency can be also attributed to the existence of Nss and Rs of the capacitors. As a result, the change in the ε‧, ε″, tanδ, M‧, M″ and ac electric conductivity (σac) is a result of restructuring and reordering of charges at the PrBaCoO/n-Si interface under an external electric field or voltage and interface polarization.

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

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

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

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

    SciTech Connect

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

    2015-05-07

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

  19. Riding the Ferris Wheel: A Sinusoidal Model

    ERIC Educational Resources Information Center

    Mittag, Kathleen Cage; Taylor, Sharon E.

    2011-01-01

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

  20. Quantification of sinusoidal cell function in vivo.

    PubMed

    Shiratori, Y; Tananka, M; Kawase, T; Shiina, S; Komatsu, Y; Omata, M

    1993-02-01

    Although the clearance and distribution of ligand molecules in circulation represent the function of hepatic sinusoidal cells, these mechanisms revealed a network that is more intricate than would at first seem, since several receptors are common to not only one type of cell, but also to two or three types of cells in the liver. In the case of latex particles in which their uptake by a particular cell type seems to be determined by their size, sinusoidal endothelial cells are able to internalize particles up to 0.23 microns under physiologic conditions, in vivo, and larger particles are taken up by Kupffer cells. However, when the phagocytic function of Kupffer cells is impaired by frog virus 3 or alcohol, endothelial cells have been found to take up particles larger than 1 micron in diameter after the injection of an excess amount of latex particles. Endothelial cells would thus constitute a second line of defense in the liver in that they remove foreign materials from the blood when Kupffer cell phagocytic function is totally disturbed. This potential role may not, however, be fully expressed under physiologic conditions when Kupffer cells are active in clearing foreign substance from the circulation. The functions of liver sinusoidal cells are varied and complex and these cells can be regarded as "a sinusoidal cell unit." This cellular interaction must be taken into account for any quantitative analysis. PMID:8446907

  1. Riding the Ferris Wheel: A Sinusoidal Model

    ERIC Educational Resources Information Center

    Mittag, Kathleen Cage; Taylor, Sharon E.

    2011-01-01

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

  2. Frequency and voltage-dependent electrical and dielectric properties of Al/Co-doped PVA/p-Si structures at room temperature

    NASA Astrophysics Data System (ADS)

    Ibrahim, Yücedağ; Ahmet, Kaya; Şemsettin, Altındal; Ibrahim, Uslu

    2014-04-01

    In order to investigate of cobalt-doped interfacial polyvinyl alcohol (PVA) layer and interface trap (Dit) effects, Al/p-Si Schottky barrier diodes (SBDs) are fabricated, and their electrical and dielectric properties are investigated at room temperature. The forward and reverse admittance measurements are carried out in the frequency and voltage ranges of 30 kHz-300 kHz and -5 V-6 V, respectively. C-V or ɛ'-V plots exhibit two distinct peaks corresponding to inversion and accumulation regions. The first peak is attributed to the existence of Dit, the other to the series resistance (Rs), and interfacial layer. Both the real and imaginary parts of dielectric constant (ɛ' and ɛ″) and electric modulus (M' and M″), loss tangent (tan δ), and AC electrical conductivity (σac) are investigated, each as a function of frequency and applied bias voltage. Each of the M' versus V and M″ versus V plots shows a peak and the magnitude of peak increases with the increasing of frequency. Especially due to the Dit and interfacial PVA layer, both capacitance (C) and conductance (G/w) values are strongly affected, which consequently contributes to deviation from both the electrical and dielectric properties of Al/Co-doped PVA/p-Si (MPS) type SBD. In addition, the voltage-dependent profile of Dit is obtained from the low-high frequency capacitance (CLF-CHF) method.

  3. A plasma aerodynamic actuator supplied by a multilevel generator operating with different voltage waveforms

    NASA Astrophysics Data System (ADS)

    Borghi, Carlo A.; Cristofolini, Andrea; Grandi, Gabriele; Neretti, Gabriele; Seri, Paolo

    2015-08-01

    In this work a high voltage—high frequency generator for the power supply of a dielectric barrier discharge (DBD) plasma actuator for the aerodynamic control obtained by the electro-hydro-dynamic (EHD) interaction is described and tested. The generator can produce different voltage waveforms. The operating frequency is independent of the load characteristics and does not require impedance matching. The peak-to-peak voltage is 30 kV at a frequency up to 20 kHz and time variation rates up to 60 kV μs-1. The performance of the actuator when supplied by several voltage waveforms is investigated. The tests have been performed in still air at atmospheric pressure. Voltage and current time behaviors have been measured. The evaluation of the energy delivered to the actuator allowed the estimation of the periods in which the plasma was ignited. Vibrational and rotational temperatures of the plasma have been estimated through spectroscopic acquisitions. The flow field induced in the region above the surface of the DBD actuator has been studied and the EHD conversion efficiency has been evaluated for the voltage waveforms investigated. The nearly sinusoidal multilevel voltage of the proposed generator and the sinusoidal voltage waveform of a conventional ac generator obtain comparable plasma features, EHD effects, and efficiencies. Inverse saw tooth waveform presents the highest effects and efficiency. The rectangular waveform generates suitable EHD effects but with the lowest efficiency. The voltage waveforms that induce plasmas with higher rotational temperatures are less efficient for the conversion of the electric into kinetic energy.

  4. High voltage power supply

    NASA Technical Reports Server (NTRS)

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

    1985-01-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-07-01

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

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

    SciTech Connect

    2012-01-23

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

  7. Pulsating laminar pipe flows with sinusoidal mass flux variations

    NASA Astrophysics Data System (ADS)

    Ünsal, B.; Ray, S.; Durst, F.; Ertunç, Ö.

    2005-11-01

    Combined analytical and experimental investigation of sinusoidal mass flow-controlled, pulsating, laminar and fully developed pipe flow was carried out. The experimental investigation employed a mass flow control unit built at LSTM-Erlangen for the present investigation. For the analytical investigation, the equations describing such flows were normalized to allow for a general solution, depending only on the normalized amplitude mA* of the mass flow pulsation and the normalized frequency F. The analytical and experimental results are presented in this normalized way and it is shown that good agreement between the results of the authors is obtained. A diagram is presented for the condition of flow reversal in terms of the dimensionless frequency F and the mass flow rate amplitude mA*.

  8. Immunological functions of liver sinusoidal endothelial cells.

    PubMed

    Knolle, Percy A; Wohlleber, Dirk

    2016-05-01

    Liver sinusoidal endothelial cells (LSECs) line the liver sinusoids and separate passenger leukocytes in the sinusoidal lumen from hepatocytes. LSECs further act as a platform for adhesion of various liver-resident immune cell populations such as Kupffer cells, innate lymphoid cells or liver dendritic cells. In addition to having an extraordinary scavenger function, LSECs possess potent immune functions, serving as sentinel cells to detect microbial infection through pattern recognition receptor activation and as antigen (cross)-presenting cells. LSECs cross-prime naive CD8 T cells, causing their rapid differentiation into memory T cells that relocate to secondary lymphoid tissues and provide protection when they re-encounter the antigen during microbial infection. Cross-presentation of viral antigens by LSECs derived from infected hepatocytes triggers local activation of effector CD8 T cells and thereby assures hepatic immune surveillance. The immune function of LSECs complements conventional immune-activating mechanisms to accommodate optimal immune surveillance against infectious microorganisms while preserving the integrity of the liver as a metabolic organ. PMID:27041636

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

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

    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.

  10. Fundamental analysis and development of the current and voltage control method by changing the driving frequency for the transcutaneous energy transmission system.

    PubMed

    Miura, Hidekazu; Yamada, Akihiro; Shiraishi, Yasuyuki; Yambe, Tomoyuki

    2015-08-01

    We have been developing transcutaneous energy transmission system (TETS) for a ventricular assist device, shape memory alloy (SMA) fibered artificial organs and so on, the system has high efficiency and a compact size. In this paper, we summarize the development, design method and characteristics of the TETS. New control methods for stabilizing output voltage or current of the TETS are proposed. These methods are primary side, are outside of the body, not depending on a communication system from the inside the body. Basically, the TETS operates at the fixed frequency with a suitable compensation capacitor so that the internal impedance is minimalized and a flat load characteristic is obtained. However, when the coil shifted from the optimal position, the coupling factor changes and the output is fluctuated. TETS has a resonant property; its output can be controlled by changing the driving frequency. The continuous current to continuous voltage driving method was implemented by changing driving frequency and setting of limitation of low side frequency. This method is useful for battery charging system for electrically driven artificial hearts and also useful for SMA fibered artificial organs which need intermittent high peak power comsumption. In this system, the internal storage capacitor is charged slowly while the fibers are turned off and discharge the energy when the fibers are turned on. We examined the effect of the system. It was found that the size and maximum output of the TETS would able to be reduced. PMID:26736511

  11. Wideband bio-impedance spectroscopy using voltage source and tetra-polar electrode configuration

    NASA Astrophysics Data System (ADS)

    Yoo, Pil Joong; Lee, Dae Hyun; In Oh, Tong; Woo, Eung Je

    2010-04-01

    Most bio-impedance spectroscopy (BIS) systems inject sinusoidal current with a variable frequency into a sample with a known geometry through a pair of electrodes. Adopting the so-called tetra-polar configuration, it measures induced voltage data on a separate pair of electrodes. Impedance spectra are plotted in a certain range of frequency. We found that its accuracy decreases at high frequencies primarily due to the deteriorated performance of the constant current source at high frequencies. Using a previous BIS system we developed, we found that the overall performance can be kept high up to several hundred kHz. In this study, we propose a design of a wideband BIS system using a constant voltage source. It is based on the simple voltage division between an internal resistor and an external sample or load. We switch the value of the internal resistor (Rs) so that the source voltage is divided more or less equally. Two pairs of electrodes are attached to the sample. Two independent voltmeters are used to separately measure two voltages across the chosen internal resistor and the sample. The voltage measurement across the sample is done between the second electrode pair only. This enables us to adopt the tetra-polar configuration to avoid the problem related with contact impedances. We describe the design, construction and performance of the new BIS system with 468 Hz to 2.2 MHz bandwidth. We will compare the results with those using the impedance analyzer.

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

    SciTech Connect

    Mokerov, V. G. Kuznetsov, A. L.; Fedorov, Yu. V.; Bugaev, A. S.; Pavlov, A. Yu.; Enyushkina, E. N.; Gnatyuk, D. L.; Zuev, A. V.; Galiev, R. R.; Ovcharenko, E. N.; Sveshnikov, Yu. N.; Tsatsulnikov, A. F.; Ustinov, V. M.

    2009-04-15

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

  13. Optimal control based on a modified quadratic performance index for systems disturbed by sinusoidal signals

    NASA Astrophysics Data System (ADS)

    Sibielak, Marek; Raczka, Waldemar; Konieczny, Jarosław; Kowal, Janusz

    2015-12-01

    The problem of optimal control of systems disturbed by sinusoidal signals for infinite control time is considered. To evaluate the control laws, a modified mean-square performance index with an infinite control time was proposed. It is based on the proposed method for the decomposition of control signals on the interval from zero to infinity into the sum of sinusoidal components with selected frequencies and an additional auxiliary signal. The performance index was formulated in such a way that each sinusoidal component corresponds to a separate weight matrix. It was shown that there are infinitely many solutions for these optimization problems. Optimal control was selected in such a way that it should be independent of the state vector, and should depend only on the disturbance signal vector. The controller was synthesized for vibration reduction system. The paper presents results of numerical and laboratory studies of the designed vehicle active suspension system.

  14. Skin Sympathetic Nerve Activity is Modulated during Slow Sinusoidal Linear Displacements in Supine Humans

    PubMed Central

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

    2016-01-01

    Low-frequency sinusoidal linear acceleration (0.08 Hz, ±4 mG) modulates skin sympathetic nerve activity (SSNA) in seated subjects (head vertical), suggesting that activation of the utricle in the peripheral vestibular labyrinth modulates SSNA. The aim of the current study was to determine whether SSNA is also modulated by input from the saccule. Tungsten microelectrodes were inserted into the common peroneal nerve to record oligounitary SSNA in 8 subjects laying supine on a motorized platform with the head aligned with the longitudinal axis of the body. Slow sinusoidal (0.08 Hz, 100 cycles) linear acceleration-decelerations (peak ±4 mG) were applied rostrocaudally to predominately activate the saccules, or mediolaterally to predominately activate the utricles. Cross-correlation histograms were constructed between the negative-going sympathetic spikes and the positive peaks of the sinusoidal stimuli. Sinusoidal linear acceleration along the rostrocaudal axis or mediolateral axis both resulted in sinusoidal modulation of SSNA (Median, IQR 27.0, 22–33% and 24.8, 17–39%, respectively). This suggests that both otolith organs act on sympathetic outflow to skin and muscle in a similar manner during supine displacements. PMID:26909019

  15. Phonological awareness and sinusoidal amplitude modulation in phonological dislexia.

    PubMed

    Peñaloza-López, Yolanda; Herrera-Rangel, Aline; Pérez-Ruiz, Santiago J; Poblano, Adrián

    2016-04-01

    Objective Dyslexia is the difficulty of children in learning to read and write as results of neurological deficiencies. The objective was to test the Phonological awareness (PA) and Sinusoidal amplitude modulation (SAM) threshold in children with Phonological dyslexia (PD). Methods We performed a case-control, analytic, cross sectional study. We studied 14 children with PD and 14 control children from 7 to 11 years of age, by means of PA measurement and by SAM test. The mean age of dyslexic children was 8.39 years and in the control group was 8.15. Results Children with PD exhibited inadequate skills in PA, and SAM. We found significant correlations between PA and SAM at 4 Hertz frequency, and calculated regression equations that predicts between one-fourth and one-third of variance of measurements. Conclusion Alterations in PA and SAM found can help to explain basis of deficient language processing exhibited by children with PD. PMID:27097001

  16. Measuring of object vibration using sinusoidal-modulation laser-diode active interferometer

    NASA Astrophysics Data System (ADS)

    Ai, Yong; Cao, Qinfeng; Lu, Su

    1996-09-01

    Using the character that the emitting optical frequency of the laser diode is controlled by the injected current, the ability of eliminating environmental disturbance of the sinusoidal modulation laser diode active interferometer will be raised by more than one hundred times through putting the disturbed interference signal produced by the environment into the interferometer. When vibrating frequency of objects is different from that of the sinusoidol modulation, 'beat- frequency' will be produced in the interfere signal, which can be analyzed to get the vibrating frequency of objects. This paper described the operation principle and theoretical delusion of the 'beat-frequency' method.

  17. Cardiorespiratory dynamics during sinusoidal and impulse exercise in man.

    PubMed

    Miyamoto, Y; Nakazono, Y; Hiura, T; Abe, Y

    1983-01-01

    Dynamic characteristics of ventilation, cardiac output, and gas exchange during sinusoidally varying work rates for the periods from 1 to 12 min and impulse work rate with a duration of 10 sec were studied on five healthy men in an upright position. Changes in work rate were given by controlling externally the electromagnetic braking system of a bicycle ergometer. Stroke volume, heart rate, and cardiac output during exercise were determined continuously by using an automated impedance cardiograph. Breath by breath determination in minute ventilation, respiratory frequency, tidal volume, oxygen consumption, carbon dioxide output, end-tidal pressures of oxygen and carbon dioxide, and gas exchange ratio were conducted. From these and steady-state response data amplitude and phase relations between each variable and the input work loads were obtained utilizing the frequency analysis techniques. The response characteristics to sinusoidal stimuli were well represented by first-order models with time constants for VE, VCO2, VO2, and Q averaging 75, 67, 52, and 36 sec, respectively. The kinetics of HR closely resembled that of Q. There was a close link between both the dynamics of VE and VCO2. On the other hand, the responses to impulse stimuli were better described by second-order models in which fast and slow response components were connected in parallel. However, the contribution of the fast component to total response was small. Although this response may support in its form the neuro-humoral concept to explain exercise hyperpnea, a tight linkage was observed between VE and VCO2 responses to impulse stimuli. Thus, hyperpnea during the unsteady-state of exercise may be explained by the cardiodynamic hypothesis. PMID:6425544

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

    PubMed Central

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

    2014-01-01

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

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

    PubMed

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

    2014-01-01

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

  20. Response of a radial-bladed centrifugal pump to sinusoidal disturbances for noncavitating flow

    NASA Technical Reports Server (NTRS)

    Anderson, D. A.; Blade, R. J.; Stevans, W.

    1971-01-01

    A radial-bladed centrifugal pump was run in water with sinusoidal fluctuations of pressure and flow rate imposed at the pump inlet. Since the flow was noncavitating, zero gain was assumed in computing pump impedance. The inertive reactance became greater than the resistance at relatively low frequencies. An electric circuit model was developed in order to explain the trends of inertance and resistance with frequency.

  1. Steady-state sinusoidal behavior of elastomeric dampers

    NASA Astrophysics Data System (ADS)

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

    1999-06-01

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

  2. Optical voltage reference

    DOEpatents

    Rankin, Richard; Kotter, Dale

    1994-01-01

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

  3. Optical voltage reference

    DOEpatents

    Rankin, R.; Kotter, D.

    1994-04-26

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

  4. Frequency dispersion of dielectric permittivity-voltage hysteresis during field driven ferroelectric-antiferroelectric-ferroelectric transition in antiferroelectric liquid crystal (SmCA*)

    NASA Astrophysics Data System (ADS)

    Rahman, Muklesur; Mukherjee, A.; Chaudhuri, B. K.; Yoshizawa, A.

    2007-04-01

    Dielectric permittivity at different polarizing states during field driven ferroelectric-ferroelectric (F-F) transition and the dielectric relaxation spectra in the antiferroelectric liquid crystal (AFLC) phase have been studied to elucidate the interaction processes involved during the transition. The unwinding process of antiferroelectric helix has been found to be governed by the polar coupling between the applied field and the antiferroelectric polarization vector followed by nonpolar interaction with the dielectric anisotropy of the tilted molecules. Frequency dependence of the permittivity-voltage hysteresis behavior observed during the F-F transitions is concluded to be due to different relaxation processes involved in the AFLC phase.

  5. Gate-tunable zero-frequency current cross correlations of the quartet state in a voltage-biased three-terminal Josephson junction

    NASA Astrophysics Data System (ADS)

    Mélin, Régis; Sotto, Moïse; Feinberg, Denis; Caputo, Jean-Guy; Douçot, Benoît

    2016-03-01

    A three-terminal Josephson junction biased at opposite voltages can sustain a phase-sensitive dc current carrying three-body static phase coherence, known as the "quartet current." We calculate the zero-frequency current noise cross correlations and answer the question of whether this current is noisy (like a normal current in response to a voltage drop) or noiseless (like an equilibrium supercurrent in response to a phase drop). A quantum dot with a level at energy ɛ0 is connected to three superconductors Sa,Sb, and Sc with gap Δ , biased at Va=V ,Vb=-V , and Vc=0 , and with intermediate contact transparencies. At zero temperature, nonlocal quartets (in the sense of four-fermion correlations) are noiseless at subgap voltage in the nonresonant dot regime ɛ0/Δ ≫1 , which is demonstrated with a semianalytical perturbative expansion of the cross correlations. Noise reveals the absence of granularity of the superflow splitting from Sc towards (Sa,Sb) in the nonresonant dot regime, in spite of finite voltage. In the resonant dot regime ɛ0/Δ ≲1 , cross correlations measured in the (Va,Vb) plane should reveal an "anomaly" in the vicinity of the quartet line Va+Vb=0 , related to an additional contribution to the noise, manifesting the phase sensitivity of cross correlations under the appearance of a three-body phase variable. Phase-dependent effective Fano factors Fφ are introduced, defined as the ratio between the amplitudes of phase modulations of the noise and the currents. At low bias, the Fano factors Fφ are of order unity in the resonant dot regime ɛ0/Δ ≲1 , and they are vanishingly small in the nonresonant dot regime ɛ0/Δ ≫1 .

  6. Influence of Ambient Humidity on the Voltage Response of Ionic Polymer-Metal Composite Sensor.

    PubMed

    Zhu, Zicai; Horiuchi, Tetsuya; Kruusamäe, Karl; Chang, Longfei; Asaka, Kinji

    2016-03-31

    Electrical potential based on ion migration exists not only in natural systems but also in ionic polymer materials. In order to investigate the influence of ambient humidity on voltage response, classical Au-Nafion IPMC was chosen as the reference sample. Voltage response under a bending deformation was measured in two ways: first, continuous measurement of voltage response in the process of absorption and desorption of water to study the tendency of voltage variation at all water states; second, measurements at multiple fixed ambient humidity levels to characterize the process of voltage response quantitatively. Ambient humidity influences the voltage response mainly by varying water content in ionic polymer. Under a step bending, the amplitude of initial voltage peak first increases and then decreases as the ambient humidity and the inherent water content decrease. This tendency is explained semiquantitatively by mass storage capacity related to the stretchable state of the Nafion polymer network. Following the initial peak, the voltage shows a slow decay to a steady state, which is first characterized in this paper. The relative voltage decay during the steady state always decreases as the ambient humidity is lowered. It is ascribed to progressive increase of the ratio between the water molecules in the cation hydration shell to the free water. Under sinusoidal mechanical bending excitation in the range of 0.1-10 Hz, the voltage magnitude increases with frequency at high ambient humidity but decreases with frequency at low ambient humidity. The relationship is mainly controlled by the voltage decay effect and the response speed. PMID:26977537

  7. Uncertainty Estimation and Performance Evaluation of a Non-sinusoidal Power Measurement Standard

    NASA Astrophysics Data System (ADS)

    Yamada, Tatsuji; Kon, Saytaro; Sakamoto, Norihiko; Kato, Hiroaki

    This paper describes the evaluations of the non-sinusoidal power measurement standard, including a wideband inductive voltage divider (IVD), shunt and sampling measurement system which are important components in the standard, at the National Metrology Institute of Japan (NMIJ). The power measurement standard measures harmonic voltages and currents up to 50th harmonic for calibrating power generators. In order to achieve uncertainties of less than 60ppm and 80ppm (k=2) for the harmonic voltage and current measurements, the wideband IVD and sampling measurement system in the standard are focused on. Its active power measurement capability has been also evaluated by intercomparison between the Japan Electric Meter Inspection Corporation (JEMIC) and NMIJ.

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

    NASA Astrophysics Data System (ADS)

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

    2008-08-01

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

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

    NASA Technical Reports Server (NTRS)

    Gabriel, G. J.

    1977-01-01

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

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

    NASA Technical Reports Server (NTRS)

    Sul, Seung K.; Lipo, Thomas A.

    1988-01-01

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

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

    PubMed

    Zivanovic, Miroslav; González-Izal, Miriam

    2013-10-01

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

  12. High sensitivity measurement system for the direct-current, capacitance-voltage, and gate-drain low frequency noise characterization of field effect transistors

    NASA Astrophysics Data System (ADS)

    Giusi, G.; Giordano, O.; Scandurra, G.; Rapisarda, M.; Calvi, S.; Ciofi, C.

    2016-04-01

    Measurements of current fluctuations originating in electron devices have been largely used to understand the electrical properties of materials and ultimate device performances. In this work, we propose a high-sensitivity measurement setup topology suitable for the automatic and programmable Direct-Current (DC), Capacitance-Voltage (CV), and gate-drain low frequency noise characterization of field effect transistors at wafer level. Automatic and programmable operation is particularly useful when the device characteristics relax or degrade with time due to optical, bias, or temperature stress. The noise sensitivity of the proposed topology is in the order of fA/Hz1/2, while DC performances are limited only by the source and measurement units used to bias the device under test. DC, CV, and NOISE measurements, down to 1 pA of DC gate and drain bias currents, in organic thin film transistors are reported to demonstrate system operation and performances.

  13. High sensitivity measurement system for the direct-current, capacitance-voltage, and gate-drain low frequency noise characterization of field effect transistors.

    PubMed

    Giusi, G; Giordano, O; Scandurra, G; Rapisarda, M; Calvi, S; Ciofi, C

    2016-04-01

    Measurements of current fluctuations originating in electron devices have been largely used to understand the electrical properties of materials and ultimate device performances. In this work, we propose a high-sensitivity measurement setup topology suitable for the automatic and programmable Direct-Current (DC), Capacitance-Voltage (CV), and gate-drain low frequency noise characterization of field effect transistors at wafer level. Automatic and programmable operation is particularly useful when the device characteristics relax or degrade with time due to optical, bias, or temperature stress. The noise sensitivity of the proposed topology is in the order of fA/Hz(1/2), while DC performances are limited only by the source and measurement units used to bias the device under test. DC, CV, and NOISE measurements, down to 1 pA of DC gate and drain bias currents, in organic thin film transistors are reported to demonstrate system operation and performances. PMID:27131690

  14. Design and implementation of a new modified sliding mode controller for grid-connected inverter to controlling the voltage and frequency.

    PubMed

    Ghanbarian, Mohammad Mehdi; Nayeripour, Majid; Rajaei, Amirhossein; Mansouri, Mohammad Mahdi

    2016-03-01

    As the output power of a microgrid with renewable energy sources should be regulated based on the grid conditions, using robust controllers to share and balance the power in order to regulate the voltage and frequency of microgrid is critical. Therefore a proper control system is necessary for updating the reference signals and determining the proportion of each inverter in the microgrid control. This paper proposes a new adaptive method which is robust while the conditions are changing. This controller is based on a modified sliding mode controller which provides adapting conditions in linear and nonlinear loads. The performance of the proposed method is validated by representing the simulation results and experimental lab results. PMID:26704720

  15. A Statistical and Spectral Model for Representing Noisy Sounds with Short-Time Sinusoids

    NASA Astrophysics Data System (ADS)

    Hanna, Pierre; Desainte-Catherine, Myriam

    2005-12-01

    We propose an original model for noise analysis, transformation, and synthesis: the CNSS model. Noisy sounds are represented with short-time sinusoids whose frequencies and phases are random variables. This spectral and statistical model represents information about the spectral density of frequencies. This perceptually relevant property is modeled by three mathematical parameters that define the distribution of the frequencies. This model also represents the spectral envelope. The mathematical parameters are defined and the analysis algorithms to extract these parameters from sounds are introduced. Then algorithms for generating sounds from the parameters of the model are presented. Applications of this model include tools for composers, psychoacoustic experiments, and pedagogy.

  16. Multifunction Current Differencing Cascaded Transconductance Amplifier (MCDCTA) and Its Application to Current-Mode Multiphase Sinusoidal Oscillator

    NASA Astrophysics Data System (ADS)

    Wang, Chunhua; Lin, Hairong

    2015-09-01

    In this study, a new versatile active element, namely multifunction current differencing cascaded transconductance amplifier (MCDCTA), is proposed. This device which adopts a simple configuration enjoys the performances of low-voltage, low-input and high-output impedance, wide bandwidth etc. It simplifies the design of the current-mode analog signal processing circuit greatly, especially the design of high-order filter and oscillator circuits. Moreover, an example as a new current-mode multiphase sinusoidal oscillator (MSO) using MCDCTA is described in this paper. The proposed oscillator, which employs only one MCDCTA and minimum grounded passive elements, is easy to be realized. It can provide random n (n being odd or even) output current signals and these output currents are equally spaced in phase all at high output impedance terminals. Its oscillation condition and the oscillation frequency can be adjusted independently, linearly and electronically by controlling the bias currents of MCDCTA. The operation of the proposed oscillator has been testified through PSPICE simulation and experimental results.

  17. Three-dimensional shape measurement with sinusoidal phase-modulating fiber-optic interferometer fringe

    NASA Astrophysics Data System (ADS)

    Lv, Changrong; Duan, Fajie; Fu, Xiao; Huang, Tingting

    2016-05-01

    A three-dimensional (3-D) shape measurement system using a fiber-optic interferometer fringe projector is presented and demonstrated. The system utilizes sinusoidal phase shifting interferometry to detect the desired phase which is improved by introducing constant scaling factors from linear phase shift interferometry algorithm, and the relationship between the modulation voltage and the phase modulation coefficient is analyzed; the system also utilizes the reflection signal to realize measurement of the disturbance and feed back to the modulated signal. Practical experiments validate the feasibility of this method. The phase accuracy is nearly 37.6 mrad and the measurement error is about 10 nm.

  18. Sinusoidal nanotextures for light management in silicon thin-film solar cells

    NASA Astrophysics Data System (ADS)

    Köppel, G.; Rech, B.; Becker, C.

    2016-04-01

    Recent progresses in liquid phase crystallization enabled the fabrication of thin wafer quality crystalline silicon layers on low-cost glass substrates enabling conversion efficiencies up to 12.1%. Because of its indirect band gap, a thin silicon absorber layer demands for efficient measures for light management. However, the combination of high quality crystalline silicon and light trapping structures is still a critical issue. Here, we implement hexagonal 750 nm pitched sinusoidal and pillar shaped nanostructures at the sun-facing glass-silicon interface into 10 μm thin liquid phase crystallized silicon thin-film solar cell devices on glass. Both structures are experimentally studied regarding their optical and optoelectronic properties. Reflection losses are reduced over the entire wavelength range outperforming state of the art anti-reflective planar layer systems. In case of the smooth sinusoidal nanostructures these optical achievements are accompanied by an excellent electronic material quality of the silicon absorber layer enabling open circuit voltages above 600 mV and solar cell device performances comparable to the planar reference device. For wavelengths smaller than 400 nm and higher than 700 nm optical achievements are translated into an enhanced quantum efficiency of the solar cell devices. Therefore, sinusoidal nanotextures are a well-balanced compromise between optical enhancement and maintained high electronic silicon material quality which opens a promising route for future optimizations in solar cell designs for silicon thin-film solar cells on glass.

  19. Sinusoidal nanotextures for light management in silicon thin-film solar cells.

    PubMed

    Köppel, G; Rech, B; Becker, C

    2016-04-28

    Recent progresses in liquid phase crystallization enabled the fabrication of thin wafer quality crystalline silicon layers on low-cost glass substrates enabling conversion efficiencies up to 12.1%. Because of its indirect band gap, a thin silicon absorber layer demands for efficient measures for light management. However, the combination of high quality crystalline silicon and light trapping structures is still a critical issue. Here, we implement hexagonal 750 nm pitched sinusoidal and pillar shaped nanostructures at the sun-facing glass-silicon interface into 10 μm thin liquid phase crystallized silicon thin-film solar cell devices on glass. Both structures are experimentally studied regarding their optical and optoelectronic properties. Reflection losses are reduced over the entire wavelength range outperforming state of the art anti-reflective planar layer systems. In case of the smooth sinusoidal nanostructures these optical achievements are accompanied by an excellent electronic material quality of the silicon absorber layer enabling open circuit voltages above 600 mV and solar cell device performances comparable to the planar reference device. For wavelengths smaller than 400 nm and higher than 700 nm optical achievements are translated into an enhanced quantum efficiency of the solar cell devices. Therefore, sinusoidal nanotextures are a well-balanced compromise between optical enhancement and maintained high electronic silicon material quality which opens a promising route for future optimizations in solar cell designs for silicon thin-film solar cells on glass. PMID:27065440

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

    NASA Astrophysics Data System (ADS)

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

    2015-06-01

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

  1. Analysis-by-Synthesis Sinusoidal Model without an Overlapping Scheme

    NASA Astrophysics Data System (ADS)

    Kim, Jong-Hark; Jeong, Gyu-Hyeok; Lee, In-Sung

    A new sinusoidal modeling approach for the analysis-by-synthesis (AbS) of parameters that characterize a linear combination of damped sinusoids is proposed. In addition to the typical sinusoidal parameters, two different damping factors, which represent the time-varying nature of speech, were used to efficiently reduce the modeling error. Even though the proposed model does not employ the overlap-adding synthesis or smoothly interpolative synthesis scheme, it shows substantially better modeling performance in the synthesis of voiced and transient segments.

  2. Self-sustained oscillations of a sinusoidally-deformed plate

    NASA Astrophysics Data System (ADS)

    Muriel, Diego F.; Cowen, Edwin A.

    2015-11-01

    Motivated by energy harvesting, the oscillatory motion of a deformed elastic material with aspect ratio Length/Width=2, immerse in an incompressible flow is studied experimentally. To induce the wave-like deformation a polycarbonate sheet is placed under longitudinal compression with external forcing provided by equispaced tension lines anchored in a frame. No additional constrains are placed in the material. Based on quantitative image-based edge detection, ADV, and PIV measurements, we document the existence of three natural states of motion. Bellow a critical velocity, a stable state presents a sinusoidal-like deformation with weak small perturbations. Above a critical velocity, instability appears in the form of a traveling wave with predictable dominant frequency accompanied by higher-order harmonics. As the flow velocity increases the instability converges faster to its limit cycle in the phase plane (e.g., vertical velocity and position), until the stable oscillatory mode transitions to chaos showing a broad energy spectrum and unstable limit cycle. The underlying objective is to induce the onset of the instability at lower critical velocities for higher bending rigidities, promoting possible energy extraction and increasing the range at which stable oscillations appear.

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

    NASA Technical Reports Server (NTRS)

    Lipo, Thomas A.; Alan, Irfan

    1991-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Lipo, Thomas A.; Alan, Irfan

    1991-06-01

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

  5. 780W narrow linewidth all fiber laser with sinusoidal phase modulation

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1990-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1990-01-01

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

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

    SciTech Connect

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

    1994-09-01

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

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

    NASA Technical Reports Server (NTRS)

    Richmond, J. H.

    1974-01-01

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

  10. Josephson Voltage Standards

    NASA Astrophysics Data System (ADS)

    Hamilton, Clark

    2001-03-01

    A Josephson junction is a perfect frequency to voltage converter, that is, V=f/KJ where K_J=2e/h=483597.9 GHz/V. This unique property has been used to convert a narrow (1 Hz) band 75 GHz reference frequency to a dc voltage standard. Josephson standards use arrays of thousands of junctions to raise the voltage to 10 V. During the last 30 years they have reduced the uncertainty in dc voltage among national measurement institutes by 3 orders of magnitude to a level of about 1 part in 10^9. More recently, the broadband capability of Josephson devices is being exploited at NIST to create a new ac voltage standard. In this case, the Josephson junction is modeled as a pulse generator that can be triggered at frequencies from dc to 20 GHz, and that produces short (approx. 50 ps) voltage pulses with a time integral of exactly 1/K_J. A Delta/Sigma algorithm with a high oversampling ratio is used to define a digital pulse sequence for any desired output waveform. The sequence is programmed into a digital code generator that triggers the Josephson device. The result is a replication of the desired waveform with a time dependent amplitude that is exactly calculable from a knowledge of the pulse code, the sampling frequency, and the number of Josephson junctions in the array. The talk will summarize progress to date on this new ac voltage standard.

  11. Frequency and voltage dependence of electric and dielectric properties of Au/TiO2/n-4H-SiC (metal-insulator-semiconductor) type Schottky barrier diodes

    NASA Astrophysics Data System (ADS)

    Tanrıkulu, E. E.; Yıldız, D. E.; Günen, A.; Altındal, Ş.

    2015-09-01

    The main electrical and dielectric properties of Au/TiO2/n-4H-SiC (MIS) type Schottky barrier diodes (SBDs) have been investigated as functions of frequency and applied bias voltage. We believe that the use of high dielectric interfacial layer between metal and semiconductor can improve the performance of Schottky diodes. From the experimental data, both electrical and dielectric parameters were found as strong function of frequency and applied bias voltage. The Fermi energy level (EF), the concentration of doping donor atoms (P), barrier height (ΦB) and series resistance (Rs) values were obtained from reverse and forward bias C-V characteristics. The changes in EF and ND with frequency are considerably low. Therefore, their values were taken at about constant. The real and imaginary parts of dielectric constant (\\varepsilon \\prime , \\varepsilon \\prime\\prime ), tangent loss (tanδ), ac electrical conductivity (σac), and real and imaginary parts of electric modulus (M‧ and M″) values were also obtained from reverse and forward bias C-V and G/ω-V characteristics. In addition, the voltage dependent profiles of all these electrical and dielectric parameters were drawn for each frequency. These results confirmed that both electrical and dielectric properties of Au/TiO2/n-4H-SiC (MIS) type SBD are quite sensitive to both the frequency and applied bias voltage due to surface polarization, density distribution of interface traps (Dit), and interfacial layer.

  12. Eye movements during afterimage tracking under sinusoidal and random vestibular stimulation

    NASA Technical Reports Server (NTRS)

    Yasui, S.; Young, L. R.

    1976-01-01

    The smooth portion of the horizontal vestibulo-ocular reflex was analyzed in terms of the frequency response, relating slow-phase eye velocity to angular velocity of a rotating chair under four different cases: sinusoidal rotation about a vertical axis in total darkness, sinusoidal rotation during afterimage tracking, pseudorandom head rotation in total darkness, and pseudorandom head rotation during afterimage tracking. Eye movements were recorded using a photoelectric limbus tracking method. The observation that the presence of an afterimage during vestibular stimulation increases the velocity of slow-phase eye movements is in support of the theory that such slow-phase movements are generated, at least in part, by the perceived velocity of the target. Since the target is immobilized on the retina, this perceived velocity is clearly not generated by retinal slip, but rather by a mechanism related to the eye movement such as corollary discharge.

  13. Spoof plasmon radiation using sinusoidally modulated corrugated reactance surfaces.

    PubMed

    Panaretos, Anastasios H; Werner, Douglas H

    2016-02-01

    In this paper we theoretically investigate the feasibility of creating leaky wave antennas capable of converting spoof plasmons to radiating modes. Spoof plasmons are surface waves excited along metallic corrugated surfaces and they are considered the microwave and THz equivalent of optical surface plasmon polaritons. Given that a corrugated surface is essentially a reactance surface, the proposed design methodology relies on engineering a corrugated surface so that it exhibits a sinusoidally modulated reactance profile. Through such non-uniform periodic reactance surfaces, guided surface waves can efficiently couple into free-space radiating modes. This requires the development of a realistic methodology that effectively maps the necessary sinusoidal reactance variation to a sinusoidal variation corresponding to the depth of the grooves. Both planar and cylindrical corrugated surfaces are examined and it is numerically demonstrated that the corresponding sinusoidally modulated leaky wave structures can very efficiently convert guided spoof plasmons to radiating modes. PMID:26906820

  14. Coherent Voltage Oscillations in Superconducting Polycrystalline Y1Ba2Cu3O7-x

    NASA Astrophysics Data System (ADS)

    Altinkok, A.; Yetiş, H.; Olutaş, M.; Kiliç, K.; Kiliç, A.; Çetin, O.

    2006-06-01

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

  15. Digital state feedback control of a three phase sinusoidal PWM inverter

    SciTech Connect

    Matin, Md.A.; Divsalar, D.

    1994-12-31

    This paper proposes a method of three phase voltage control sinusoidal PWM (Pulse Width Modulation) inverter. The state equation of the inverter main circuit has been derived and transformed to the d-q frame. Afterwards, an algorithm of dead-beat control has been developed by considering only the load current as disturbing variable. The advantage of dead-beat control is that it can control very fast within short time (sampling period) comparing to other methods. The main objective of the controller design is to get the sinusoidal voltage at inverter`s output with low harmonic distortions. To compensate the calculation delay and to realize physically, a 3d order prediction method has been adopted. A new switching technique has been developed. This switching technique can reduce unnecessary switching so that switching loss can be minimized. Finally, simulations has been done under a typical load condition (rectifier with capacitor load) and harmonic analysis has also been done. Throughout all simulations, very good results have been found where total harmonic distortions (THD) is less than 5%.

  16. Role of sinusoidal heparan sulfate proteoglycan in liver metastasis formation.

    PubMed

    Tvri, J; Paku, S; Rs, E; Pogny, G; Kovalszky, I; Ladnyi, A; Lapis, K; Tmr, J

    1997-05-29

    Previous studies have indicated that the predominant sites of tumor cell extravasation in the liver are the sinusoidal vessels, where tumor cells contact the sinusoidal endothelium and the subendothelial extracellular matrix containing the basic components of the basement membrane. We studied the role of sinusoidal extracellular matrix in metastatsis formation by 3LL-HH murine tumor cells selected for their preferential liver colonization. 3LL-HH tumor cells did not efficiently adhere to cryosections of the liver, but they recognized the sinusoids and vessel walls. Pre-treatment of the mice with polyclonal anti-basement membrane antibodies [anti-laminin, anti-fibronectin and anti-heparan sulfate proteoglycan (HSPG)] significantly modulated the organ distribution of tumor cell colonies following intracardial injection: all 3 antibodies inhibited kidney colonization; anti-laminin and anti-fibronectin antibodies inhibited lung colonization; and only anti-HSPG antibody inhibited liver colonization. In several organs such as the heart, stomach, pancreas and bladder, anti-basement membrane antibody treatment did not alter the process of colonization. Immunofluorescence studies showed that anti-HSPG antibody recognized the basement membranes of sinusoids and blood vessels. Our data suggest a specific involvement of sinusoidal HSPG in the liver colonization of 3LL-HH cells. PMID:9180152

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

    SciTech Connect

    Zhou, Yong-Jie; Yuan, Qiang-Hua; Li, Fei; Wang, Xiao-Min; Yin, Gui-Qin; Dong, Chen-Zhong

    2013-11-15

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

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

    NASA Astrophysics Data System (ADS)

    Zhou, Yong-Jie; Yuan, Qiang-Hua; Li, Fei; Wang, Xiao-Min; Yin, Gui-Qin; Dong, Chen-Zhong

    2013-11-01

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

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

    NASA Technical Reports Server (NTRS)

    Balla, R. Jeffrey; Miller, Corey A.

    2008-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

  1. Speckle suppression in pattern projection profilometry with a thin sinusoidal phase grating by polychromatic illumination

    NASA Astrophysics Data System (ADS)

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

    2013-03-01

    Pattern projection profilometry is a powerful tool to reconstruct three-dimensional (3D) surface of diffuse objects. A variety of pattern projection methods for 3D capture of objects is based on the generation of sinusoidal fringes. A sinusoidal phase grating under divergent coherent illumination with a point source produces high visibility and high spectral purity sinusoidal fringes in a large longitudinal region. In the present work we study the speckle suppression in the fringes by using a polychromatic light source. Such an approach makes use of the fact that the lateral fringe spacing does not depend on the wavelength of the illuminating light. The wavelength has an impact on the locations and the number of the Talbot planes, where self-imaging of the grating occurs, and on variation of the contrast and the frequency content of fringes along the distance from the grating. We analyze the multi-wavelength illumination of the grating by solving the Fresnel diffraction integral for a point source illumination in paraxial approximation. We verified the obtained results by experiments with a thin holographic grating recorded on a silver-halide holographic plate under illumination with a laser diode operating in single mode and multimode regimes.

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

    PubMed Central

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

    1986-01-01

    The light-growth response of Phycomyces has been studied with the sum-of-sinusoids method of nonlinear system identification (Victor, J.D., and R.M. Shapley, 1980, Biophys. J., 29:459). This transient response of the sporangiophore has been treated as a black-box system with one input (logarithm of the light intensity, I) and one output (elongation rate). The light intensity was modulated so that log I, as a function of time, was a sum of sinusoids. The log-mean intensity was 10(-4) W m-2 and the wavelength was 477 nm. The first- and second-order frequency kernels, which represent the linear and nonlinear behavior of the system, were obtained from the Fourier transform of the response at the appropriate component and combination frequencies. Although the first-order kernel accounts for most of the response, there remains a significant nonlinearity beyond the logarithmic transducer presumed to occur at the input of the sensory transduction chain. From the analysis of the frequency kernels, we have derived a dynamic nonlinear model of the light-growth response system. The model consists of a nonlinear subsystem followed by a linear subsystem. The model parameters were estimated from a combined nonlinear least-squares fit to the first- and second-order frequency kernels. PMID:3779003

  3. High-Voltage, Asymmetric-Waveform Generator

    NASA Technical Reports Server (NTRS)

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

    2008-01-01

    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).

  4. Thresholds for the perception of whole-body linear sinusoidal motion in the horizontal plane

    NASA Technical Reports Server (NTRS)

    Mah, Robert W.; Young, Laurence R.; Steele, Charles R.; Schubert, Earl D.

    1989-01-01

    An improved linear sled has been developed to provide precise motion stimuli without generating perceptible extraneous motion cues (a noiseless environment). A modified adaptive forced-choice method was employed to determine perceptual thresholds to whole-body linear sinusoidal motion in 25 subjects. Thresholds for the detection of movement in the horizontal plane were found to be lower than those reported previously. At frequencies of 0.2 to 0.5 Hz, thresholds were shown to be independent of frequency, while at frequencies of 1.0 to 3.0 Hz, thresholds showed a decreasing sensitivity with increasing frequency, indicating that the perceptual process is not sensitive to the rate change of acceleration of the motion stimulus. The results suggest that the perception of motion behaves as an integrating accelerometer with a bandwidth of at least 3 Hz.

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

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

    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 λ/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.

  6. Calibrating angular transducer using sinusoidal and shock excitation

    NASA Astrophysics Data System (ADS)

    Zhang, Li; Peng, Jun

    2012-06-01

    Primary angular vibration calibration system and primary angular shock calibration system are developed by Changcheng Institute of Metrology and Measurement (CIMM). The both systems using laser interferometer and grating measure rotational angle, angular velocity and angular acceleration, which are traceable to the International System of Units (SI). This paper will study the dynamic performance of an angular accelerometer and a gyro under the excitation of sinusoidal and shock using the calibration systems. It shows that the angular transducers should be calibrated using both sinusoidal and shock excitation to obtain more detailed dynamic information.

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

    NASA Technical Reports Server (NTRS)

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

    1976-01-01

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

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

    SciTech Connect

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

    2010-04-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2005-06-01

    The nonlinear behavior of a sinusoidally modulated rotating disk electrode (RDE) is analyzed to identify the flow and concentration field interactions that lead to resonance and nullification conditions in the electrochemical response of the system. Steady periodic solutions to the von Kármán self-similar form of the Navier-Stokes equations and convective diffusion equation are examined using a combined Fourier transform/perturbation approach that yields a set of frequency dispersion equations solved using the finite element method. Experimental measurements using a RDE with sinusoidal angular velocity waveform Ω =Ω0+ΔΩcos(ω0t) are compared to theory for modulation amplitudes ΔΩ /Ω0<1 and electrolyte Schmidt number of 1680. The modulation frequency ω0 is varied from the quasisteady to high-frequency limits to obtain the phase and amplitude of the mean, fundamental, and higher-harmonic limiting current. We show that distinct features (resonances and nullifications) in the nonlinear mean and higher harmonic components of limiting current result from constructive and destructive (in phase and 180° out of phase, respectively) interactions between cross terms of the oscillating components in the axial flow and concentration fields near the disk surface.

  10. Sinusoidal Regge Oscillations from Short Lived Resonances

    NASA Astrophysics Data System (ADS)

    Sokolovski, D.; Felfli, Z.; Msezane, A. Z.

    2007-06-01

    It is well known that a resonance with a large angular life can produce sharp Breit-Wigner peaks in the energy dependence of integral cross sections [1,2]. Here we show that a short-lived resonance whose angular life is of order of one full rotation may produce a different kind of contribution to the integral cross section. This contribution has a sinousoidal form and its frequency is determined by the rotational constant of the complex. As one of the examples, we analyze the Regge oscillations observed in numerical simulations of the F+H2(v=0,j=0,φ=0) ->FH(v'=2,j'=0,φ'=0) + H reaction. In particular, we show that these oscillations are produced by two overlapping resonances located near the transition state and the van der Waals well, respectively [3]. [1] J. H. Macek, et al., Phys. Rev. Lett., 93, 183202, (2004). [2] Z. Felfli et al., J. Phys. B 39, L353 (2006) [3] D. Sokolovski, D. De Fazio, S. Cavalli and V. Aquilanti, J. Chem. Phys. (2007) (submitted).

  11. VOLTAGE REGULATOR

    DOEpatents

    Von Eschen, R.L.; Scheele, P.F.

    1962-04-24

    A transistorized voltage regulator which provides very close voitage regulation up to about 180 deg F is described. A diode in the positive line provides a constant voltage drop from the input to a regulating transistor emitter. An amplifier is coupled to the positive line through a resistor and is connected between a difference circuit and the regulating transistor base which is negative due to the difference in voltage drop across thc diode and the resistor so that a change in the regulator output causes the amplifier to increase or decrease the base voltage and current and incrcase or decrease the transistor impedance to return the regulator output to normal. (AEC)

  12. Measurement of micromovements with the help of a nonlinear sinusoidal oscillator and an inductive sensor

    SciTech Connect

    Bayard, J.

    2005-03-01

    Proximity magnetic sensors are based on an induction coil that creates a magnetic field. The presence of a metal target in the vicinity of this coil modifies the properties of the field created by the coil and consequently the value of its equivalent R/L circuit. The sensor is usually used as a coil to fix the frequency value of a sinusoidal oscillator. The types of oscillators used (and the suggested linear analysis) do not make it possible to determine the oscillation amplitude value. So, designers of such sensors have to connect the distance target/sensor only to the variation of the oscillation frequency value. We propose the development of a nonlinear oscillator that allows linking oscillation amplitude and parallel resistance of the sensor. One can thus connect the distance target/sensor to the amplitude and/or the frequency of the oscillation.

  13. Estimating Sinusoidal Pressure Waves In A Pump Volute

    NASA Technical Reports Server (NTRS)

    Szabo, Roland J.; Chon, Juliet T.

    1994-01-01

    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.

  14. Compressed Sensing Of Complex Sinusoids Off The Grid

    NASA Astrophysics Data System (ADS)

    Ping, Cheng; Liu, Shi; Jiaqun, Zhao

    2015-07-01

    To solve off-grid problem in compressed sensing, a new reconstruction algorithm for complex sinusoids is proposed. The compressed sensing reconstruction problem is transformed into a joint optimized problem. Based on coordinate descent approach and linear estimator, a new iteration algorithm is proposed. The results of experiments verify the effectiveness of the proposed method.

  15. Using Antenna Arrays to Motivate the Study of Sinusoids

    ERIC Educational Resources Information Center

    Becker, J. P.

    2010-01-01

    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…

  16. G-seat system step input and sinusoidal response characteristics

    NASA Technical Reports Server (NTRS)

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

    1978-01-01

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

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

    NASA Technical Reports Server (NTRS)

    Nayfeh, A. H.

    1974-01-01

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

  18. Using Antenna Arrays to Motivate the Study of Sinusoids

    ERIC Educational Resources Information Center

    Becker, J. P.

    2010-01-01

    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

  19. Highly stretchable gold nanobelts with sinusoidal structures for recording electrocorticograms.

    PubMed

    Qi, Dianpeng; Liu, Zhiyuan; Yu, Mei; Liu, Yan; Tang, Yuxin; Lv, Junhui; Li, Yuchun; Wei, Jun; Liedberg, Bo; Yu, Zhe; Chen, Xiaodong

    2015-05-27

    Rationally designed sinusoidal gold nanobelts are fabricated as stretchable electrodes, and they do not show obvious change of resistance under large deformation after 10,000 cyclic stretching/relaxing processes. As a proof of concept, they are successfully used to record intracranial electroencephalogram or electrocorticogram signals from rats. PMID:25865755

  20. 3D reconstruction for sinusoidal motion based on different feature detection algorithms

    NASA Astrophysics Data System (ADS)

    Zhang, Peng; Zhang, Jin; Deng, Huaxia; Yu, Liandong

    2015-02-01

    The dynamic testing of structures and components is an important area of research. Extensive researches on the methods of using sensors for vibration parameters have been studied for years. With the rapid development of industrial high-speed camera and computer hardware, the method of using stereo vision for dynamic testing has been the focus of the research since the advantages of non-contact, full-field, high resolution and high accuracy. But in the country there is not much research about the dynamic testing based on stereo vision, and yet few people publish articles about the three-dimensional (3D) reconstruction of feature points in the case of dynamic. It is essential to the following analysis whether it can obtain accurate movement of target objects. In this paper, an object with sinusoidal motion is detected by stereo vision and the accuracy with different feature detection algorithms is investigated. Three different marks including dot, square and circle are stuck on the object and the object is doing sinusoidal motion by vibration table. Then use feature detection algorithm speed-up robust feature (SURF) to detect point, detect square corners by Harris and position the center by Hough transform. After obtaining the pixel coordinate values of the feature point, the stereo calibration parameters are used to achieve three-dimensional reconstruction through triangulation principle. The trajectories of the specific direction according to the vibration frequency and the frequency camera acquisition are obtained. At last, the reconstruction accuracy of different feature detection algorithms is compared.

  1. Thermal conductivity measurements using 1ω and 3ω methods revisited for voltage-driven setups

    NASA Astrophysics Data System (ADS)

    Kimling, J.; Martens, S.; Nielsch, K.

    2011-07-01

    1ω and 3ω methods are widely established transient measurement techniques for the characterization of thermal transport in bulk-materials, thin films, and 1D nano-objects. These methods are based on resistance oscillations of a heater caused by Joule-heating from a sinusoidal current at frequency 1ω which lead to changes in the 1ω voltage and produce a voltage component at 3ω. Although the usual formalism for analyzing the measurement data assumes an ideal current source, voltage-driven measurement setups are employed in many cases. In this context, we find that there has been lack of clarity if a correction generally has to be considered when analyzing the measurement data from voltage driven setups. In this work, Fourier-analysis is employed to show that a correction is not required for 1ω methods and for 3ω measurements that use common-mode-subtraction. Experimental results are presented for a line heater on a fused silica substrate with known thermal properties, and for an individual nickel wire with diameter of 150 nm.

  2. Frequency analysis of DC tolerant current transformers

    NASA Astrophysics Data System (ADS)

    Mlejnek, P.; Kaspar, P.

    2013-09-01

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

  3. Investigation of Calibrating Force Transducer Using Sinusoidal Force

    SciTech Connect

    Zhang Li; Wang Yu; Zhang Lizhe

    2010-05-28

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

  4. Detection of noise-corrupted sinusoidal signals with Josephson junctions

    NASA Astrophysics Data System (ADS)

    Filatrella, Giovanni; Pierro, Vincenzo

    2010-10-01

    We investigate the possibility of exploiting the speed and low noise features of Josephson junctions for detecting sinusoidal signals masked by Gaussian noise. We show that the escape time from the static locked state of a Josephson junction is very sensitive to a small periodic signal embedded in the noise, and therefore the analysis of the escape times can be employed to reveal the presence of the sinusoidal component. We propose and characterize two detection strategies: in the first, the initial phase is supposedly unknown (incoherent strategy), while in the second, the signal phase remains unknown but is fixed (coherent strategy). Our proposals are both suboptimal, with the linear filter being the optimal detection strategy, but they present some remarkable features, such as resonant activation, that make detection through Josephson junctions appealing in some special cases.

  5. fiber optic interferometer fringe projector using sinusoidal phase-modulating

    NASA Astrophysics Data System (ADS)

    Lv, Changrong; Duan, Fajie; Zhang, Fukai; Duan, Xiaojie; Bo, En; Feng, Fan

    2013-10-01

    A novel fiber-optic interferometer fringe projector with the sinusoidal phase-modulating method is presented. The system utilizes the integrating bucket method to detect the desired phase or the displacement and a CMOS image sensor to detect four frames obtained by integration of the time-varying intensity in an interference image during the four quarters of the modulation period. Since this technique with the method modulating the injection current of the piezoelectric transducer (PZT), measurement accuracy is not affected by an intensity modulation that usually appears in the current modulation. The system also utilizes the Fresnel reflection signal to adjust the phase-modulation coefficient z to eliminate the disturbance of initial phase ψ0 . The experimental results for surface profiles of a convex hull show that the sinusoidal phase modulating interferometer proposed here confirms its applicability to practical application.

  6. Sinusoidal modulation control method in a chaotic neural network

    NASA Astrophysics Data System (ADS)

    Zhang, Qihanyue; Xie, Xiaoping; Zhu, Ping; Chen, Hongping; He, Guoguang

    2014-08-01

    Chaotic neural networks (CNNs) have chaotic dynamic associative memory properties: The memory states appear non-periodically, and cannot be converged to a stored pattern. Thus, it is necessary to control chaos in a CNN in order to recognize associative memory. In this paper, a novel control method, the sinusoidal modulation control method, has been proposed to control chaos in a CNN. In this method, a sinusoidal wave simplified from brain waves is used as a control signal to modulate a parameter of the CNN. The simulation results demonstrate the effectiveness of this control method. The controlled CNN can be applied to information processing. Moreover, the method provides a way to associate brain waves by controlling CNNs.

  7. The physical basis of perceived roughness in virtual sinusoidal textures.

    PubMed

    Unger, Bertram; Klatzky, Roberta; Hollis, Ralph

    2013-01-01

    Using a high-fidelity haptic interface based on magnetic levitation, subjects explored virtual sinusoidal textures with a frictionless probe and reported the subjective magnitude of perceived roughness. A psychophysical function was obtained spanning 33 levels of spatial periods from 0.025 to 6.00 mm. Kinematic and dynamic variables were recorded at 1,000 Hz and used to derive a set of variables to correlate with the psychophysical outcome. These included position, velocity, kinetic energy, instantaneous force (based on acceleration), mean force, and variability of the z-axis force signal from the power spectral density. The analysis implicates power of the force signal as the physical correlate of perceived roughness of sinusoidal textures. The relationship between power and roughness held across the range of spatial periods examined. PMID:24808401

  8. 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)

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

    2015-02-01

    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.

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

    PubMed

    Avramov, Ivan D

    2005-08-01

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

  10. Nonlinear frequency chirp measurement of frequency sweeping lasers for FD-OCT applications

    NASA Astrophysics Data System (ADS)

    Ahn, Tae-Jung; Kim, Dug Young

    2006-02-01

    A noble measurement method by using a homodyne interferometer and Hilbert transform has been proposed for characterizing frequency sweeping light sources used in traditional optical frequency domain reflectometer (OFDR) and optical frequency domain imaging (OFDI). A Michelson interferometer with a tunable laser generates a sinusoidal beating signal. A phase of measured beating signal as a function of time is approximately proportional to optical frequency of the swept light source during frequency tuning and can be obtained by the Hilbert transformation. Thus, optical frequency chirp can be determined by a simple equation related with the phase of the beating signal from the interferometer. We have demonstrated the effectiveness and the simplicity of our proposed method by testing a temperature-tuned frequency sweeping DFB-LD and a commercial external cavity tunable laser source as practical examples. In the case of DFB-LD, the frequency sweep becomes more linear while the amount of frequency sweep saturates as the amplitude of the control voltage applied to a TEC driver increases, and the frequency-tuning rate increases as the repetition rate decreases. We also found that a commercial frequency-sweeping laser has a feed back control to adjust its frequency-sweeping rate such that the tuning rate oscillates around an intended value as a function of time. We have demonstrated the possibility of using a self-homodyne interferometer as a powerful tool for characterizing frequency sweeping laser sources. We expect this method will be useful for improving the performance of many optical frequency domain measurement techniques such as OFDR, FD-OCT or OFDI.

  11. Nonlinear propagation of sinusoidal pulse laser beam in homogeneous plasma

    SciTech Connect

    Upadhyay, Ajay K.; Raj, Gaurav; Mishra, Rohit K.; Malviya, Amita; Jha, Pallavi

    2007-09-15

    The propagation of an intense laser beam, having a sinusoidal pulse profile, in underdense plasma, is analyzed. Applying variational technique and using a standard trial function for the laser pulse amplitude, simultaneous equations describing the evolution of pulse length and spot size are obtained. Relativistic nonlinearity, finite pulse length, and group velocity dispersion effects have been taken into account. Using numerical methods, a graphical analysis of simultaneous evolution of laser spot size and pulse length is presented.

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

    NASA Technical Reports Server (NTRS)

    Hodge, W. H.

    1973-01-01

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

  13. Phase extraction based on sinusoidal extreme strip phase shifting method

    NASA Astrophysics Data System (ADS)

    Hui, Mei; Liu, Ming; Dong, Liquan; Liu, Xiaohua; Zhao, Yuejin

    2015-08-01

    Multiple synthetic aperture imaging can enlarge pupil diameter of optical systems, and increase system resolution. Multiple synthetic aperture imaging is a cutting-edge topic and research focus in recent years, which is prospectively widely applied in fields like astronomical observations and aerospace remote sensing. In order to achieve good imaging quality, synthetic aperture imaging system requires phase extraction of each sub-aperture and co-phasing of whole aperture. In the project, an in-depth study about basic principles and methods of segments phase extraction was done. The study includes: application of sinusoidal extreme strip light irradiation phase shift method to extract the central dividing line to get segment phase extraction information, and the use of interference measurement to get the aperture phase extraction calibration coefficients of spherical surface. Study about influence of sinusoidal extreme strip phase shift on phase extraction, and based on sinusoidal stripe phase shift from multiple linear light sources of the illumination reflected image, to carry out the phase shift error for inhibiting the effect in the phase extracted frame.

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

    PubMed Central

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

    2014-01-01

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

  15. Aperiodic sinusoidal fringes in comparison to phase-shifted sinusoidal fringes for high-speed three-dimensional shape measurement

    NASA Astrophysics Data System (ADS)

    Heist, Stefan; Lutzke, Peter; Kühmstedt, Peter; Notni, Gunther

    2015-09-01

    In order to optically reconstruct the three-dimensional (3-D) surface shape of moving objects or deformation processes, aside from high-speed cameras, high-speed projectors and/or short projection sequences are necessary. One approach is to project a series of aperiodic sinusoidal fringes, e.g., by using an array projector that can achieve frame rates of several 10 kHz. So far, we have demonstrated the fundamental functionality of a 3-D sensor based on this projection technique. Now the measurement principle itself is to be compared with phase-shifting fringe projection as probably the most widely used technique. Theoretical considerations as well as experimental investigations are conducted to derive criteria for the design of optimal sequences of aperiodic sinusoidal fringes and to compare the number of patterns of both approaches necessary for comparable accuracies.

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

    USGS Publications Warehouse

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

    1999-01-01

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

  17. Resonant fiber optic gyro based on a sinusoidal wave modulation and square wave demodulation technique.

    PubMed

    Wang, Linglan; Yan, Yuchao; Ma, Huilian; Jin, Zhonghe

    2016-04-20

    New developments are made in the resonant fiber optic gyro (RFOG), which is an optical sensor for the measurement of rotation rate. The digital signal processing system based on the phase modulation technique is capable of detecting the weak frequency difference induced by the Sagnac effect and suppressing the reciprocal noise in the circuit, which determines the detection sensitivity of the RFOG. A new technique based on the sinusoidal wave modulation and square wave demodulation is implemented, and the demodulation curve of the system is simulated and measured. Compared with the past technique using sinusoidal modulation and demodulation, it increases the slope of the demodulation curve by a factor of 1.56, improves the spectrum efficiency of the modulated signal, and reduces the occupancy of the field-programmable gate array resource. On the basis of this new phase modulation technique, the loop is successfully locked and achieves a short-term bias stability of 1.08°/h, which is improved by a factor of 1.47. PMID:27140098

  18. Measuring the 3D shape of high temperature objects using blue sinusoidal structured light

    NASA Astrophysics Data System (ADS)

    Zhao, Xianling; Liu, Jiansheng; Zhang, Huayu; Wu, Yingchun

    2015-12-01

    The visible light radiated by some high temperature objects (less than 1200 °C) almost lies in the red and infrared waves. It will interfere with structured light projected on a forging surface if phase measurement profilometry (PMP) is used to measure the shapes of objects. In order to obtain a clear deformed pattern image, a 3D measurement method based on blue sinusoidal structured light is proposed in this present work. Moreover, a method for filtering deformed pattern images is presented for correction of the unwrapping phase. Blue sinusoidal phase-shifting fringe pattern images are projected on the surface by a digital light processing (DLP) projector, and then the deformed patterns are captured by a 3-CCD camera. The deformed pattern images are separated into R, G and B color components by the software. The B color images filtered by a low-pass filter are used to calculate the fringe order. Consequently, the 3D shape of a high temperature object is obtained by the unwrapping phase and the calibration parameter matrixes of the DLP projector and 3-CCD camera. The experimental results show that the unwrapping phase is completely corrected with the filtering method by removing the high frequency noise from the first harmonic of the B color images. The measurement system can complete the measurement in a few seconds with a relative error of less than 1 : 1000.

  19. Development of a sinusoidal phase-shifting self-mixing interferometer for real-time displacement measurement with nanometer accuracy

    NASA Astrophysics Data System (ADS)

    Xia, Wei; Yang, Zhenyu; Liu, Qiang; Wang, Ming; Hao, Hui; Guo, Dongmei

    2013-05-01

    By combining the principles of sinusoidal phase-shifting technique and self-mixing interferometry, a novel instrument has been developed for real-time displacement measurement with nanometer accuracy. The sinusoidal phase shifting is introduced by an electro-optic modulator and the displacement of the object is measured by analyzing the harmonic components in the interference signal during each phase-shifting period. Theoretical analysis and simulation results are presented and some error sources are discussed in detail. The displacement measurement experiments by using a high precision nano-positioning stage and a long-range linear stage are performed to verify the performance of the interferometer. The measurement results of the interferometer are in good agreement with the data from a commercial dual-frequency interferometer, showing that the development of the interferometer is feasible for implementation in a real-time displacement sensor with high accuracy.

  20. Constant-amplitude, frequency- independent phase shifter

    NASA Technical Reports Server (NTRS)

    Deboo, G. J.

    1971-01-01

    Electronic circuit using operational amplifiers provides output with constant phase shift amplitude, with respect to sinusoidal input, over wide range of frequencies. New circuit includes field effect transistor, Q, operational amplifiers, A1 and A2, and phase detector.

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

    PubMed Central

    Chen, Hongtao

    2013-01-01

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

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

    PubMed Central

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

    2015-01-01

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

  3. Determination of the magnetic losses in laminated cores under pulse width modulation voltage supply

    NASA Astrophysics Data System (ADS)

    Vidal, N.; Gandarias, K.; Almandoz, G.; Poza, J.

    2015-08-01

    In the laminated ferromagnetic cores employed in transformers and electrical machines energy losses occur resulting in a warming effect and efficiency decrease. Normally, manufacturers only provide iron losses data when a sinusoidal voltage supply is applied, but the actual operating characteristics of electrical machines include non-sinusoidal supplies, in particular pulse-width modulation (PWM). This information can be experimentally obtained, but only measuring systems that have function generators with arbitrarily programmable waveforms allow measurements in the presence of higher harmonics. Therefore, having an analytical tool to obtain the most accurate estimation of the magnetic losses is of great interest in addressing the design of electric machines. This paper validates an analytical-expression-based procedure, which delivers results with acceptable accuracy under all operating conditions for the estimation of losses in laminated cores. In addition, it investigates the influence of the modulation amplitude and the switching frequency of the PWM signals in the magnetic losses of soft magnetic materials. For this purpose, non-oriented fully processed electrical steel strips have been measured in a commercial AC permeameter using a single strip tester.

  4. High-Speed Frequency Modulation of a 460-GHz Gyrotron for Enhancement of 700-MHz DNP-NMR Spectroscopy

    NASA Astrophysics Data System (ADS)

    Idehara, T.; Khutoryan, E. M.; Tatematsu, Y.; Yamaguchi, Y.; Kuleshov, A. N.; Dumbrajs, O.; Matsuki, Y.; Fujiwara, T.

    2015-09-01

    The high-speed frequency modulation of a 460-GHz Gyrotron FU CW GVI (the official name in Osaka University is Gyrotron FU CW GOI) was achieved by modulation of acceleration voltage of beam electrons. The modulation speed f m can be increased up to 10 kHz without decreasing the modulation amplitude δ f of frequency. The amplitude δ f was increased almost linearly with the modulation amplitude of acceleration voltage Δ V a. At the Δ V a = 1 kV, frequency spectrum width df was 50 MHz in the case of f m < 10 kHz. The frequency modulation was observed as both the variation of the IF frequency in the heterodyne detection system measured by a high-speed oscilloscope and the widths of frequency spectra df measured on a frequency spectrum analyzer. Both results well agree reasonably. When f m exceeds 10 kHz, the amplitude δ f is decreased gradually with increasing f m because of the degradation of the used amplifier in response for high-speed modulation. The experiment was performed successfully for both a sinusoidal wave and triangle wave modulations. We can use the high-speed frequency modulation for increasing the enhancement factor of the dynamic nuclear polarization (DNP)-enhanced nuclear magnetic resonance (NMR) spectroscopy, which is one of effective and attractive methods for the high-frequency DNP-NMR spectroscopy, for example, at 700 MHz. Because the sensitivity of NMR is inversely proportional to the frequency, high-speed frequency modulation can compensate the decreasing the enhancement factor in the high-frequency DNP-NMR spectroscopy and keep the factor at high value. In addition, the high-speed frequency modulation is useful for frequency stabilization by a PID control of an acceleration voltage by feeding back of the fluctuation of frequency. The frequency stabilization in long time is also useful for application of a DNP-NMR spectroscopy to the analysis of complicated protein molecules.

  5. Thixotropy and Rheopexy of Muscle Fibers Probed Using Sinusoidal Oscillations

    PubMed Central

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

    2015-01-01

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

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

    PubMed

    Mortazavi, Daryoush; Kouzani, Abbas; Kalani, Mahshid

    2014-08-11

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

  7. Sinusoidal calibration technique for Large Binocular Telescope system

    NASA Astrophysics Data System (ADS)

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

    2008-07-01

    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.

  8. Method and apparatus for spur-reduced digital sinusoid synthesis

    NASA Technical Reports Server (NTRS)

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

    1995-01-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2009-02-01

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

  10. Estimation of the sinusoidal oscillation parameters in the adaptive optics system based on the example of the photovoltaic system

    NASA Astrophysics Data System (ADS)

    Kania, Dariusz

    2015-05-01

    In adaptive optics systems, there is a problem of a sinusoidal oscillations rejection. This paper presents the estimation method that can be used to reject these oscillations on the example of the photovoltaic system. In such a system, photovoltaic panels generate the DC signal converted by the inverter to the AC signal with specified parameters. This paper focuses on the fast and accurate estimation of these parameters taking into account the presence of harmonics in the sinusoidal signal. The estimation method is based on using maximum decay sidelobes windows and the Fast Fourier Transform procedure. In reality, the AC signal is not a pure sinusoid and it is often distorted in a deterministic manner by harmonics, and in a random manner by white, "colored" or quantization noise. The estimation error depends on the systematic error, i.e. the error caused by the quantization noise and the error caused by harmonic components. Several parameters determine which error component is dominant in the estimation results. The value of the error caused by harmonic components depends mainly on the distance between the harmonic component and the fundamental component in a frequency domain and the THD (Total Harmonic Distortion) ratio of the signal. The level of this maximum relative error is approximately 10-3 for the tested signal with THD=50%. It is important to use a filter that reduces unwanted harmonics before the data processing. The information provided in this paper can be used to determine the approximate level of estimation error before starting the estimation process.

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

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Adachi, Kazunari; Konno, Takuma; Kosugi, Satoshi

    2015-06-01

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

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

    NASA Technical Reports Server (NTRS)

    Lipo, Thomas A.; Sood, Pradeep K.

    1987-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2011-10-01

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

  15. Electronic Shore Power Station Based on Matrix-style Frequency Algorithm

    NASA Astrophysics Data System (ADS)

    Jia-sheng, Li; Lian-jun, Jiang; Biao, Qiu; Wu-mei, Yang

    The current port power supply to foreign ships, there are two ways power-type for owned diesel-powered and frequency conversion unit,In this paper,Proposed electronic shore power station, put forward electronic shore power station's concepts, and gives a whole building program of electronic shore power station based on matrix conversion algorithm, It will change 10 kV/50 Hz (35Kv/50 Hz) input voltage into 440 V/60 Hz low-voltage, not only eliminating intermediate links, but also simplify the hardware circuit and reduce the production cost and improve the competitiveness of enterprises. Simulation and experimental results show that this program has a built shore power station of high power factor, sinusoidal effective, low distortion, environmental pollution and the advantages,It will be very definite practical significance.

  16. Voltage-dependent capacitance of human embryonic kidney cells

    PubMed Central

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

    2009-01-01

    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 781.25 Hz 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, Ψ. C can be described by: C = C(0) (1+α(Ψ+ ψs)2) [where C(0): Capacitance at 0 volts, ψs: Difference in surface potential between cytoplasmic and extracellular leaflets and α: Proportionality constant]. We find that α and ψs 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 Ψ, 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 (≈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 Ψ 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 (7×104 electrons, 10 pF cell) with that determined for prestin transfected cells (up to 5×106 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

  17. Voltage-dependent capacitance of human embryonic kidney cells

    NASA Astrophysics Data System (ADS)

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

    2006-04-01

    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 781.25Hz 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, Ψ . C can be described by: C=C(0)(1+α(Ψ+ψs)2) [where C(0) : Capacitance at 0volts , ψs : Difference in surface potential between cytoplasmic and extracellular leaflets and α : Proportionality constant]. We find that α and ψs 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 10mM sodium salicylate was added to the extracellular solution. This suggests that salicylate does not affect the rate at which C grows with Ψ , but reduces the charge asymmetry of the membrane. We also observe an additional linear differential capacitance of about (-46fFV-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 (≈1pN) 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 Ψ 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 ( 7×104 electrons, 10pF cell) with that determined for prestin transfected cells (up to 5×106 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.

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

    SciTech Connect

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

    2007-11-26

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

  19. The dynamics of repeated impacts with a sinusoidally vibrating table

    NASA Astrophysics Data System (ADS)

    Holmes, P. J.

    1982-09-01

    A deceptively simple difference equation is derived which approximately describes the motion of a small ball bouncing vertically on a massive sinusoidally vibrating plate. In the case of perfect elastic impacts, the equation reduces to the "standard mapping" which has been extensively studied by physicists in connection with the motions of particles constrained in potential wells. It is shown that, for sufficiently large excitation velocities and a coefficient of restitution close to one, this deterministic dynamical system exhibits large families of irregular non-periodic solutions in addition to the expected harmonic and subharmonic motions. The physical significance of these and other chaotic motions which appear to occur frequently in non-linear oscillations is discussed.

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

    PubMed

    Fan, Cathy Q; Crawford, James M

    2014-12-01

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

  1. Representative Sinusoids for Hepatic Four-Scale Pharmacokinetics Simulations

    PubMed Central

    Schwen, Lars Ole; Schenk, Arne; Kreutz, Clemens; Timmer, Jens; Bartolomé Rodríguez, María Matilde; Kuepfer, Lars; Preusser, Tobias

    2015-01-01

    The mammalian liver plays a key role for metabolism and detoxification of xenobiotics in the body. The corresponding biochemical processes are typically subject to spatial variations at different length scales. Zonal enzyme expression along sinusoids leads to zonated metabolization already in the healthy state. Pathological states of the liver may involve liver cells affected in a zonated manner or heterogeneously across the whole organ. This spatial heterogeneity, however, cannot be described by most computational models which usually consider the liver as a homogeneous, well-stirred organ. The goal of this article is to present a methodology to extend whole-body pharmacokinetics models by a detailed liver model, combining different modeling approaches from the literature. This approach results in an integrated four-scale model, from single cells via sinusoids and the organ to the whole organism, capable of mechanistically representing metabolization inhomogeneity in livers at different spatial scales. Moreover, the model shows circulatory mixing effects due to a delayed recirculation through the surrounding organism. To show that this approach is generally applicable for different physiological processes, we show three applications as proofs of concept, covering a range of species, compounds, and diseased states: clearance of midazolam in steatotic human livers, clearance of caffeine in mouse livers regenerating from necrosis, and a parameter study on the impact of different cell entities on insulin uptake in mouse livers. The examples illustrate how variations only discernible at the local scale influence substance distribution in the plasma at the whole-body level. In particular, our results show that simultaneously considering variations at all relevant spatial scales may be necessary to understand their impact on observations at the organism scale. PMID:26222615

  2. Representative Sinusoids for Hepatic Four-Scale Pharmacokinetics Simulations.

    PubMed

    Schwen, Lars Ole; Schenk, Arne; Kreutz, Clemens; Timmer, Jens; Bartolomé Rodríguez, María Matilde; Kuepfer, Lars; Preusser, Tobias

    2015-01-01

    The mammalian liver plays a key role for metabolism and detoxification of xenobiotics in the body. The corresponding biochemical processes are typically subject to spatial variations at different length scales. Zonal enzyme expression along sinusoids leads to zonated metabolization already in the healthy state. Pathological states of the liver may involve liver cells affected in a zonated manner or heterogeneously across the whole organ. This spatial heterogeneity, however, cannot be described by most computational models which usually consider the liver as a homogeneous, well-stirred organ. The goal of this article is to present a methodology to extend whole-body pharmacokinetics models by a detailed liver model, combining different modeling approaches from the literature. This approach results in an integrated four-scale model, from single cells via sinusoids and the organ to the whole organism, capable of mechanistically representing metabolization inhomogeneity in livers at different spatial scales. Moreover, the model shows circulatory mixing effects due to a delayed recirculation through the surrounding organism. To show that this approach is generally applicable for different physiological processes, we show three applications as proofs of concept, covering a range of species, compounds, and diseased states: clearance of midazolam in steatotic human livers, clearance of caffeine in mouse livers regenerating from necrosis, and a parameter study on the impact of different cell entities on insulin uptake in mouse livers. The examples illustrate how variations only discernible at the local scale influence substance distribution in the plasma at the whole-body level. In particular, our results show that simultaneously considering variations at all relevant spatial scales may be necessary to understand their impact on observations at the organism scale. PMID:26222615

  3. Sinusoidal Obstruction Syndrome (Hepatic Veno-Occlusive Disease)

    PubMed Central

    Fan, Cathy Q.; Crawford, James M.

    2014-01-01

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

  4. Ultradian rhythmicity of tyrosine aminotransferase activity in Euglena gracillis: Analysis by cosine and non-sinusoidal fitting procedures

    NASA Astrophysics Data System (ADS)

    Neuhaus-Steinmetz, Ulrich; Balzer, Ivonne; Hardeland, Rüdiger

    1990-03-01

    Although the geophysical periodicity of the earth's rotation corresponds to a biological cyclicity of ca. 24 h, cellular temporal organization comprises a multifrequency time structure, in which ultradian rhythms may be regarded as subelements of the circadian oscillator. In Euglena gracilis kept under conditons in which various cellular functions oscillate with a circadian period, tyrosine aminotransferase activity exhibited predominantly an ultradian cycle, whereas its circadian frequency was only weakly expressed. Ultradian period lengths were in the range of 4 5 h, as demonstrated by least squares fitting of cosines and of a non-sinusoidal regression function.

  5. Pupillary responses to single and sinusoidal light stimuli in diabetic patients

    PubMed Central

    Zangemeister, Wolfgang H.; Gronow, Thilo; Grzyska, Ulrich

    2009-01-01

    We examined effects of diabetes mellitus (DM) on the pupillary light reflex (PLR). Phasic pupillary response to a single light stimulus (200 ms) (pPLR) and to continuous sinusoidal stimuli with four different frequencies (0.1, 0.3, 0.7, 1.3Hz) (cPLR) were examined in 52 DM patients and 21 control subjects. We asked: does recording and frequency analysis of cPLR together with short time fourier [STFT] analysis of pPLR differentiate better between DM patients and normal subjects than pPLR only? Initial pupil diameter was significantly decreased in the DM group. For pPLR. maximal contraction velocity (Vmax), Vmax of redilation 1, reflex-amplitude and pPLR latency were significantly reduced in those patients who also showed signs of diabetic autonomic neuropathy (DNP). Tests of dynamic pupillary light reflex (cPLR) revealed that all DM patients had a significantly reduced gain at lower frequencies. Pupil phase lag was greater at 0.1 and 0.3Hz and smaller at 0.7 and 1.3 Hz in the DNP group (p<0.001). Comparison of single pPLR recordings of 5 DNP patients with 5 subjects using short time fast fourier (STFT) analysis revealed a characteristic change from low frequency content in healthy subjects to high frequency content in DNP patients. Significant changes in the PLR in DM can be found only when symptoms of autonomic neuropathy have been shown. Both sympathetic and the parasympathetic nervous systems are affected by diabetic autonomic neuropathy. Only recording of cPLR, together with STFT of pPLR can identify significant pathological deficits of pupillary control in single cases. PMID:21577356

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

    SciTech Connect

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

    1991-01-10

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

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

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

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

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

    PubMed

    Petrinović, Davor; Brezović, Marko

    2011-04-01

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

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

    NASA Astrophysics Data System (ADS)

    Nag, Tanay; Sen, Diptiman; Dutta, Amit

    2015-06-01

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

  10. Experimental studies for determining human discomfort response to vertical sinusoidal vibration

    NASA Technical Reports Server (NTRS)

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

    1975-01-01

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

  11. Experimental Investigation of Dynamic Stall on a NACA0012 Airfoil Undergoing Sinusoidal Pitching

    NASA Astrophysics Data System (ADS)

    Bohl, Douglas; Green, Melissa

    2015-11-01

    In this work, the flow field around a NACA0012 Airfoil undergoing large amplitude sinusoidal pitching is investigated using Particle Image Velocimetry (PIV). The airfoil is pitched symmetrically about the quarter chord point with a peak angle of 20 deg, at reduced frequencies of k =0.2-0.6 and Rec = 12000. Sixteen different Fields of View are phase averaged and combined to quantify the flow field from 0.75c upstream of the leading edge to 1c downstream of the trailing edge. This provides spatially and temporally resolved data sets that include the downstream evolution of the flow fields. The velocity and vorticity fields, both around the airfoil and downstream of the trailing edge, will be investigated as a function of the reduced frequency to better understand the dynamics (i.e. formation, separation and development) of the leading edge vortex and the resulting downstream flow evolution. This work was supported by the Office of Naval Research under ONR Award No. N00014-14-1-0418.

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

    DOEpatents

    Praeg, W.F.

    1982-03-09

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

  13. 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 ...

  14. Sinusoidal Wave Estimation Using Photogrammetry and Short Video Sequences

    PubMed Central

    Rupnik, Ewelina; Jansa, Josef; Pfeifer, Norbert

    2015-01-01

    The objective of the work is to model the shape of the sinusoidal shape of regular water waves generated in a laboratory flume. The waves are traveling in time and render a smooth surface, with no white caps or foam. Two methods are proposed, treating the water as a diffuse and specular surface, respectively. In either case, the water is presumed to take the shape of a traveling sine wave, reducing the task of the 3D reconstruction to resolve the wave parameters. The first conceived method performs the modeling part purely in 3D space. Having triangulated the points in a separate phase via bundle adjustment, a sine wave is fitted into the data in a least squares manner. The second method presents a more complete approach for the entire calculation workflow beginning in the image space. The water is perceived as a specular surface, and the traveling specularities are the only observations visible to the cameras, observations that are notably single image. The depth ambiguity is removed given additional constraints encoded within the law of reflection and the modeled parametric surface. The observation and constraint equations compose a single system of equations that is solved with the method of least squares adjustment. The devised approaches are validated against the data coming from a capacitive level sensor and on physical targets floating on the surface. The outcomes agree to a high degree. PMID:26690171

  15. Sinusoidal Wave Estimation Using Photogrammetry and Short Video Sequences.

    PubMed

    Rupnik, Ewelina; Jansa, Josef; Pfeifer, Norbert

    2015-01-01

    The objective of the work is to model the shape of the sinusoidal shape of regular water waves generated in a laboratory flume. The waves are traveling in time and render a smooth surface, with no white caps or foam. Two methods are proposed, treating the water as a diffuse and specular surface, respectively. In either case, the water is presumed to take the shape of a traveling sine wave, reducing the task of the 3D reconstruction to resolve the wave parameters. The first conceived method performs the modeling part purely in 3D space. Having triangulated the points in a separate phase via bundle adjustment, a sine wave is fitted into the data in a least squares manner. The second method presents a more complete approach for the entire calculation workflow beginning in the image space. The water is perceived as a specular surface, and the traveling specularities are the only observations visible to the  cameras, observations that are notably single image. The depth ambiguity is removed given additional constraints encoded within the law of reflection and the modeled parametric surface. The observation and constraint equations compose a single system of equations that is solved with the method of least squares adjustment. The devised approaches are validated against the data coming from a capacitive level sensor and on physical targets floating on the surface. The outcomes agree to a high degree. PMID:26690171

  16. Exact laminar solutions for flows in channels with sinusoidal walls

    NASA Astrophysics Data System (ADS)

    Vadarevu, Sabarish; Sharma, Ati; Ganapathisubramani, Bharathram

    2015-11-01

    We compute exact solutions for steady, incompressible, laminar flows in sinusoidal channels using Newton's method, employing domain transformation with spectral resolution in all spatial directions. Aligning the walls to be in phase has made computations considerably cheap (runtime/case ~ 10 minutes on 1 core); Newton's method has allowed tracing solutions into high Reynolds number ranges, where solutions are temporally unstable. We identify four parameters: the amplitude, maximum slope, and streamwise inclination of the grooves/furrows in the surfaces, as well as the mean pressure gradient that drives the flow. Results are presented for amplitudes ranging from 0.1% to 10% of channel half-height, and maximum slopes ranging from 0.3 to 3.0, for a set of inclinations and Reynolds numbers. We look at the onset and sizes of steady recirculation zones, their effect on the volume flux, and relative contributions of pressure and wall-shear to total drag. The strengths of shear layers and the wall-normal gradients of circulation are considered as indicators for Kelvin-Helmholtz and centrifugal instabilities respectively. Future work will focus on computing other classes of exact solutions and understanding their significance to transition and turbulence.

  17. Molecular response of liver sinusoidal endothelial cells on hydrogels.

    PubMed

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

    2015-06-01

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

  18. Low-frequency noise in serial arrays of MgO-based magnetic tunnel junctions

    NASA Astrophysics Data System (ADS)

    Zhang, Wenzhe; Hao, Qiang; Xiao, Gang

    2011-09-01

    We have studied the low-frequency noise in MgO-based magnetic tunnel junctions (MTJs) in serial configurations. Two types of junctions were compared: MTJ Wheatstone bridges and MTJ discrete resistors closely packed on a wafer die. We have characterized each individual junction to ensure that they have uniform parameters such as linear field sensitivity and noise level. In the array of bridges, the low-frequency noise decreases with an increasing number (N) of bridges, but does not scale with 1/N, as expected from noise theory. The deviation is likely due to the statistical dispersions in MTJ bridge resistance and normalized voltage noise. The total noise of the discrete resistor series does not scale with 1/N either, but rather exhibits a sinusoidal-like variation with N. We attribute it to the possible enhancement of noise from magnetic coupling among the tightly spaced MTJ elements.

  19. Analysis and Control of Pulse-Width Modulated AC to DC Voltage Source Converters.

    NASA Astrophysics Data System (ADS)

    Wu, Rusong

    The pulse width modulated AC to DC voltage source converter is comprehensively analyzed in the thesis. A general mathematical model of the converter is first established, which is discontinuous, time-variant and non-linear. The following three techniques are used to obtain closed form solutions: Fourier analysis, transformation of reference frame and small signal linearization. Three models, namely, a steady-state DC model, a low frequency small signal AC model and a high frequency model, are consequently developed. Finally, three solution sets, namely, the steady-state solution, various dynamic transfer functions and the high frequency harmonic components, are obtained from the three models. Two control strategies, the Phase and Amplitude Control (PAC) and a new proposed strategy, Predicted Current Control with a Fixed Switching Frequency (PCFF), are investigated. Based on the transfer functions derived from the above mentioned analysis, regulators for a closed-loop control are designed. A prototype circuit is built to experimentally verify the theoretical predictions. The analysis and experimental results show that both strategies produce nearly sinusoidal line current with unity power factor on the utility side in both rectifying and regenerating operations and concurrently provide a regulated DC output voltage on the load side. However the proposed PCFF control has a faster and improved dynamic response over the PAC control. Moreover it is also easier to be implemented. Therefore, the PCFF control is preferable to the PAC control. As an example of application, a configuration of variable DC supply under PCFF control is proposed. The quasi-optimal dynamic response obtained shows that the PWM AC to DC converter lays the foundation for building a four-quadrant, fast-dynamic system, and the PCFF control is an effective strategy for improving dynamic performances not only as applied to the AC to DC converter, but also as applied to the DC to DC chopper or other circuits.

  20. Characterization of combined power plasma jet using AC high voltage and nanosecond pulse for reactive species composition control

    NASA Astrophysics Data System (ADS)

    Takashima, Keisuke; Konishi, Hideaki; Kato, Toshiaki; Kaneko, Toshiro

    2014-10-01

    In the application studies for both bio-medical and agricultural applications, the roles of the reactive oxide and/or nitride species generated in the plasma has been reported as a key to control the effects and ill-effects on the living organism. The correlation between total OH radical exposure from an air atmospheric pressure plasma jet and the sterilization threshold on Botrytis cinerea is presented. With the increase of the OH radical exposure to the Botrytis cinerea, the probability of sterilization is increased. In this study, to resolve the roles of reactive species including OH radicals, a combined power plasma jet using nanosecond pulses and low-frequency sinusoidal AC high voltage (a few kHz) is studied for controlling the composition of the reactive species. The nanosecond pulses are superimposed on the AC voltage which is in synchronization with the AC phase. The undergoing work to characterize the combined power discharge with electric charge and voltage cycle on the plasma jet will also be presented to discuss the discharge characteristics to control the composition of the reactive species.

  1. The analysis of indexed astronomical time series - XII. The statistics of oversampled Fourier spectra of noise plus a single sinusoid

    NASA Astrophysics Data System (ADS)

    Koen, Chris

    2015-10-01

    With few exceptions, theoretical studies of periodogram properties focus on pure noise time series. This paper considers the case in which the time series consists of noise together with a single sinusoid, observed at regularly spaced time points. The distribution of the periodogram ordinates in this case is shown to be of exponentially modified Gaussian form. Simulations are used to demonstrate that if the periodogram is substantially oversampled (i.e. calculated in a dense grid of frequencies), then the distribution of the periodogram maxima can be accurately approximated by a simple form (at least at moderate signal-to-noise ratios). This result can be used to derive a calculation formula for the probability of correct signal frequency identification at given values of the time series length and (true) signal-to-noise ratio. A set of curves is presented which can be used to apply the theory to, for example, asteroseismic data. An illustrative application to Kepler data is given.

  2. Tusanqi-Related Sinusoidal Obstruction Syndrome in China

    PubMed Central

    Wang, Xiaoxi; Qi, Xingshun; Guo, Xiaozhong

    2015-01-01

    Abstract In West, sinusoidal obstruction syndrome (SOS) is often complicated with hemopoietic stem cell transplantation. By comparison, in China, SOS is frequently caused by Tusanqi-containing pyrrolizidine alkaloids. A systematic review aimed to evaluate the clinical profiles, diagnostic workup, treatment, and outcomes of Tusanqi-related SOS in China. All relevant articles were searched via PubMed, China Knowledge Resource Integrated, VIP, and Wanfang databases. Case reports were defined, as the data were available in every individual patient. Otherwise, case series were defined. Overall, 106 articles were eligible. Fifty-six case reports included 84 individual patients with SOS secondary to Tusanqi alone. All of them presented with ascites, but only 1 patient presented with upper gastrointestinal bleeding. The 1-, 3-, and 6-month cumulative survival rate was 98%, 87%, and 76%, respectively. Increased bilirubin and aspartate transaminase levels were significantly associated with poor outcome. Thirty-one case series included 402 patients with SOS secondary to Tusanqi alone. Ascites was observed in 94% of patients, but upper gastrointestinal bleeding was observed in 40% of patients. Recovery, stabilization, progression, and death were observed in 41%, 30%, 14%, and 16% of patients, respectively. Nineteen case series included 281 patients with SOS secondary to mixed etiologies. The pooled proportion of Tusanqi-related SOS was 66% (95% confidence interval: 56%–75%). Tusanqi is a major cause of SOS in China. Ascites is the most common clinical presentation of Tusanqi-related SOS. Despite a relatively good short-term outcome, further studies should be necessary to explore the long-term outcome and refine the treatment strategy. PMID:26061322

  3. Electro-Optical High-Voltage Sensors

    NASA Technical Reports Server (NTRS)

    Gottsche, Allan; Johnston, Alan R.

    1992-01-01

    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.

  4. Multilevel cascade voltage source inverter with separate DC sources

    DOEpatents

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

    1997-06-24

    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.

  5. Multilevel cascade voltage source inverter with seperate DC sources

    DOEpatents

    Peng, Fang Zheng; Lai, Jih-Sheng

    2001-04-03

    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.

  6. Multilevel cascade voltage source inverter with seperate DC sources

    DOEpatents

    Peng, Fang Zheng; Lai, Jih-Sheng

    2002-01-01

    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.

  7. Multilevel cascade voltage source inverter with seperate DC sources

    DOEpatents

    Peng, Fang Zheng; Lai, Jih-Sheng

    1997-01-01

    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.

  8. Genetic ablation of placental sinusoidal trophoblast giant cells causes fetal growth restriction and embryonic lethality.

    PubMed

    Outhwaite, J E; McGuire, V; Simmons, D G

    2015-08-01

    A specialized subtype of trophoblast giant cells (TGCs) line the torturous sinusoids of the murine placental labyrinth, and can be distinguished from most other TGCs by the expression of Ctsq. We generated a transgenic mouse line expressing Cre recombinase from the Ctsq promoter. Crosses with Cre-inducible tdTomato reporter mice indicated Cre activity was restricted to the sinusoidal TGCs of the labyrinth, as well as the recently characterized channel TGCs. When crossed with Cre-inducible DTA transgenic mice, ablation of sinusoidal TGCs was achieved in double transgenic embryos, resulting in fetal growth restriction by E16.5, and embryonic lethality by term. PMID:26091829

  9. Green's functions of the scalar model of electromagnetic fields in sinusoidal superlattices

    NASA Astrophysics Data System (ADS)

    Ignatchenko, V. A.; Tsikalov, D. S.

    2016-03-01

    Problems of obtaining Green's function and using it for studying the structure of scalar electromagnetic fields in a sinusoidal superlattice are considered. An analytical solution of equation in the k-space for Green's function is found. Green's function in the r-space is obtained by both the numerical and the approximate analytical Fourier transformation of that solution. It is shown, that from the experimental study of Green's function in the k-space the position of the plane radiation source relative to the extremes of the dielectric permittivity ε(z) can be determined. The relief map of Green's function in the r-space shows that the structure of the field takes the form of chains of islets in the plane ωz, the number of which increases with increasing the distance from a radiation source. This effect leads to different frequency dependences of Green's function at different distances from the radiation source and can be used to measure the distance to the internal source. The real component of Green's function and its spatial decay in the forbidden zones in the near field is investigated. The local density of states, depending on the position of the source in the superlattice, is calculated.

  10. Liver sinusoidal endothelial cells and acute non-oxidative hepatic injury induced by Pseudomonas aeruginosa pyocyanin

    PubMed Central

    Cheluvappa, Rajkumar; Cogger, Victoria C; Kwun, Sun Young; O’Reilly, Jennifer N; Le Couteur, David G; Hilmer, Sarah N

    2008-01-01

    The liver sinusoidal endothelial cell (LSEC) is damaged by many toxins, including oxidants and bacterial toxins. Any effect on LSECs of the Pseudomonas aeruginosa virulence factor, pyocyanin, may be relevant for systemic pseudomonal infections and liver transplantation. In this study, the effects of pyocyanin on in vivo rat livers and isolated LSECs were assessed using electron microscopy, immunohistochemistry and biochemistry. In particular, the effect on fenestrations, a crucial morphological aspect of LSECs was assessed. Pyocyanin treatment induced a dose-dependent reduction in fenestrations in isolated LSECs. In the intact liver, intraportal injection of pyocyanin (11.9 μM in blood) was associated with a reduction in endothelial porosity from 3.4 ± 0.2% (n = 5) to 1.3 ± 0.1% (n = 7) within 30 min. There were decreases in both diameter and frequency of fenestrations in the intact endothelium. There was also a decrease in endothelial thickness from 175.8 ± 5.8 to 156.5 ± 4.0 nm, an endothelial pathology finding previously unreported. Hepatocyte ultrastructure, liver function tests and immunohistochemical markers of oxidative stress (3-nitrotyrosine and malondialdehyde) were not affected. Pyocyanin induces significant ultrastructural changes in the LSEC in the absence of immunohistochemical evidence of oxidative stress or hepatocyte injury pointing to a novel mechanism for pyocyanin pathogenesis. PMID:19134050

  11. Differential Sampling For Fast Acquisition Of Frequency

    NASA Technical Reports Server (NTRS)

    Kumar, Rajendra

    1990-01-01

    Algorithm rapidly estimates frequency of sinusoidal signal corrupted by zero-mean, additive, white Gaussian noise. Incorporates differential mathematical model of signal, cyclic sampling of signal, and least-squares best-estimate criterion. Adapts to changing signal frequency. Amount of computation required to obtain estimate increases only linearly with number of successive measurements processed.

  12. High Voltage Lines: Hazard at a Distance.

    ERIC Educational Resources Information Center

    Marino, Andrew A.; Becker, Robert O.

    1978-01-01

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

  13. Theoretical considerations on aperiodic sinusoidal fringes in comparison to phase-shifted sinusoidal fringes for high-speed three-dimensional shape measurement.

    PubMed

    Heist, Stefan; Kühmstedt, Peter; Tünnermann, Andreas; Notni, Gunther

    2015-12-10

    The demand for optically reconstructing the three-dimensional (3D) surface shape of moving objects or deformation processes makes the development of high-speed projectors necessary. Our 3D sensor containing an array projector can achieve frame rates of several tens of kilohertz and is based on the projection of aperiodic sinusoidal fringes. This approach is compared with phase-shifting fringe projection as probably the most widely used technique. Theoretical considerations as well as extensive simulations are conducted to derive criteria for the design of optimal sequences of aperiodic sinusoidal fringes and to compare the number of patterns of both approaches necessary for comparable accuracies. PMID:26836883

  14. An experimental distribution of analog and digital information in a hybrid wireless visible light communication system based on acousto-optic modulation and sinusoidal gratings

    NASA Astrophysics Data System (ADS)

    Gómez Colín, R.; García Juárez, A.; Zaldívar Huerta, I. E.; Marquina, A. Vera; García Delgado, L. A.; Leal Cruz, A. L.; Gómez Fuentes, R.

    2016-03-01

    In this paper we propose a photonic architecture as an alternative tool to distribute point to multipoint analog and digital information over a hybrid wireless visible optical communication system. The experimental set-up is composed of a red laser pointer, an acousto-optic modulator, a sinusoidal grating and a photo-detector array. By using a simple and variable interferometric system, diffraction gratings with different spatial frequencies are generated and recorded on a photoemulsion which is composed of vanilla with dichromate gelatin. Analog video and digital information are first transmitted and recovered over a wireless communication system using a microwave carrier at 4.52 GHz which is generated by distributed feedback lasers operating in the low laser threshold current region. Separately, the recovered video information and digital data are combined with a radio frequency signal of 80 MHz, obtaining a subcarrier of information that is imposed on the optical carrier of the pointer laser using an acousto-optic modulator which is operated with an angle of incident light that satisfies the Bragg condition. The modulated optical carrier is sent to a sinusoidal grating, the diffraction pattern is photo-detected using an array of PIN photo-detectors. The use of sinusoidal gratings with acousto-optic modulators allows that number of channels to be increased when both components are placed in cascade.

  15. Procedure for Deconvolution of Time-Dependent Signals with Sinusoidal Shape

    SciTech Connect

    Todorov, M. D.; Djulgerova, R.; Mihailov, V.; Koperski, J.

    2008-10-30

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

  16. Ultrastructural study of the endothelial cells in teleost liver sinusoids under normal and experimental conditions.

    PubMed

    Ferri, S; Sesso, A

    1981-01-01

    The ultrastructure of the endothelial cells of liver sinusoids was studied in the teleost, Pimelodus maculatus. These cells have the ability to form pinocytotic vacuoles, starting with the formation of marginal folds. The latter occur in many cells after stimulation by India ink injections and ink particles are ingested by pinocytosis and by micropinocytosis. Desmosomes, structures rarely described between liver sinusoidal endothelial cells, are present in this species. PMID:7273119

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

    SciTech Connect

    Groot, Peter de

    2009-12-10

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

  18. Controlling the shape of the ion energy distribution at constant ion flux and constant mean ion energy with tailored voltage waveforms

    NASA Astrophysics Data System (ADS)

    Bruneau, Bastien; Lafleur, Trevor; Booth, Jean-Paul; Johnson, Erik

    2016-04-01

    In this paper, we investigate the excitation of a capacitively coupled plasma using a non-sinusoidal voltage waveform whose amplitude- and slope-asymmetry varies continuously with a period which is a multiple of the fundamental RF period. We call this period the ‘beating’ period. Through particle-in-cell (PIC) simulations, we show that such waveforms cause oscillation of the self-bias at this beating frequency, corresponding to the charging and discharging of the external capacitor. The amplitude of this self-bias oscillation depends on the beating period, the value of the external capacitor, and the ion flux to the electrodes. This self-bias oscillation causes temporal modulation of the ion flux distribution function (IFDF), albeit at a constant ion flux and constant mean ion energy, and allows the energy width of the IFDF (averaged over the beating period) to be varied in a controlled fashion.

  19. Precision voltage regulator

    NASA Technical Reports Server (NTRS)

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

    1972-01-01

    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.

  20. Association of idiopathic hepatic sinusoidal dilatation with the immunological features of the antiphospholipid syndrome

    PubMed Central

    Saadoun, D; Cazals-Hatem, D; Denninger, M-H; Boudaoud, L; Pham, B-N; Mallet, V; Condat, B; Brière, J; Valla, D

    2004-01-01

    Background: Isolated sinusoidal dilatation is an uncommon hepatic lesion and the cause is largely unknown. Objective: To investigate whether prothrombotic disorders or perisinusoidal cell changes could be involved in pure idiopathic hepatic sinusoidal dilatation (HSD). Methods: Evaluation for associated conditions, prothrombotic disorders, and studies of hepatic perisinusoidal cell activation in consecutive patients, seen between 1993 and 2002, with isolated sinusoidal dilatation unrelated to outflow block, sinusoidal infiltration, or hepatic granulomas. Results: Among 11 patients, associated conditions were prothrombotic disorders (n = 5) and oral contraceptive use (n = 3). Prothrombotic disorders were polycythemia vera (n = 1) and anticardiolipin antibodies combined with lupus anticoagulant (n = 4). No genetic thrombophilia factor was found. Of four patients with lupus anticoagulant, three had antinuclear factors and high serum levels of anticardiolipin antibodies at repeated testing. There was no evidence of intrahepatic or extrahepatic thrombosis in any of the patients. Sinusoidal dilatation was marked in six of 11 patients (54%), including two patients with antiphospholipid antibodies. Activated perisinusoidal cells were only found around markedly dilated sinusoids. Conclusion: Idiopathic pure HSD is frequently associated with the immunological features of the antiphospholipid syndrome. Therefore, finding pure HSD in a liver biopsy specimen should prompt the search for antiphospholipid antibodies. PMID:15361506

  1. Investigation of voltage swell mitigation using STATCOM

    NASA Astrophysics Data System (ADS)

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

    2013-06-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

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

  3. Electromagnetic environment and interference transmission characteristics of a TEM waveguide for transient signals by the use of a damped sinusoidal

    NASA Astrophysics Data System (ADS)

    Briest, N.; Garbe, H.; Potthast, S.

    2015-11-01

    This article broaches the issue of the propagation of transient signals in gigahertz transverse electromagnetic (GTEM) cells. As a representative for transient signals a damped sinusoidal (DS) is used with three different mid-band frequencies. The signal transmission of the DS in the GTEM1250 is qualified and discussed on the basis of the Pearson correlation coefficient (Pcc). The Pcc gives an overview of the signal transmission quality for all measuring points within the testvolume and signal distortions can be identified. A 100 MHz DS is weakly distorted in several measuring points. The Pcc at those points decreases and a signal shape variance can be assumed. Furthermore inhomogeneities of the GTEM1250 caused by the cell door can be identified.

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

    SciTech Connect

    Li Jinhuan; Sasaki, Osami

    2011-07-10

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

  5. Three dimensional dynamic study of a metal halide thallium iodine discharge plasma powered by a sinusoidal and square signal

    NASA Astrophysics Data System (ADS)

    Bechir Ben Hamida, Mohamed; Charrada, Kamel

    2016-01-01

    The purpose of this paper is to study the dynamic of a metal halide thallium iodine discharge lamp fed by a sinusoidal and square power supply. For this, a chemical model under Local Thermodynamic Equilibrium conditions has been developed to compute the plasma composition and transport coefficients such as thermal conductivity, viscosity and electric conductivity. This is then coupled with a three-dimensional time-dependent code that solves the system of the mass, energy and momentum equations, as well as the Laplace equation for the plasma using Comsol Multiphysics with Matlab. After validation with the experimental results, this model was applied to analyze the influence of the key parameters on the discharge behavior such as frequency for an AC arc current and the atomic ratio for square arc-current wave form on the convective process.

  6. Characteristics and performance of offset phase locked single frequency heterodyned laser systems

    NASA Astrophysics Data System (ADS)

    Tulchinsky, David A.; Hastings, Alexander S.; Williams, Keith J.

    2016-05-01

    We demonstrate and characterize the performance of two heterodyned optical phase locked loop (PLL) laser systems for use in characterizing photodetector RF frequency response and nonlinearities. Descriptions of PLL circuit parameters for Nd:YAG non-planar ring oscillator lasers at 1064 nm and 1319 nm, and Er ion fiber lasers from 1530 nm to 1565 nm are presented. Both laser systems have piezoelectric transducer wavelength control over the PLL voltage controlled oscillator circuit. Offset frequency phase locking from 1.5 kHz to 51+ GHz is demonstrated. Frequency stability at 10 MHz is measured to be ±50 μHz, limited by the stability of the Rb stabilized crystal oscillator. Phase noise of the phase-locked 1319 nm laser system is discussed where we find that the phase noise is dominated by the input source noise at frequency offsets below 100 Hz and by the laser's RIN noise at frequency offsets > 100 Hz. Comparing nonlinearity data from an InGaAs p-i-n photodiode using both 1319 nm and 1550 nm PLL nonlinearity measurement systems, we find two new separate photodetector nonlinearity mechanisms. Measurements of the harmonic components of a 11 MHz sinusoidal heterodyned optical beat note signal are found to be at or below 1 nW/mW for the second harmonic (at 22 MHz) and at or below 0.25 nW/mW for the 3rd harmonic (at 33 MHz), confirming the nearly pure sinusoidal nature of the optically generated microwave beat note.

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

    SciTech Connect

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

    2013-09-01

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

  8. HIGH VOLTAGE GENERATOR

    DOEpatents

    Zito, G.V.

    1959-04-21

    This patent relates to high voltage supply circuits adapted for providing operating voltages for GeigerMueller counter tubes, and is especially directed to an arrangement for maintaining uniform voltage under changing conditions of operation. In the usual power supply arrangement for counter tubes the counter voltage is taken from across the power supply output capacitor. If the count rate exceeds the current delivering capaciiy of the capacitor, the capacitor voltage will drop, decreasing the counter voltage. The present invention provides a multivibrator which has its output voltage controlled by a signal proportional to the counting rate. As the counting rate increases beyond the current delivering capacity of the capacitor, the rectified voltage output from the multivibrator is increased to maintain uniform counter voltage.

  9. Transient Voltage Recorder

    NASA Astrophysics Data System (ADS)

    Medelius, Pedro J.; Simpson, Howard J.

    2002-09-01

    A voltage transient recorder can detect lightning induced transient voltages. The recorder detects a lightning induced transient voltage and adjusts input amplifiers to accurately record transient voltage magnitudes. The recorder stores voltage data from numerous monitored channels, or devices. The data is time stamped and can be output in real time, or stored for later retrieval. The transient recorder, in one embodiment, includes an analog-to-digital converter and a voltage threshold detector. When an input voltage exceeds a pre-determined voltage threshold, the recorder stores the incoming voltage magnitude and time of arrival. The recorder also determines if its input amplifier circuits clip the incoming signal or if the incoming signal is too low. If the input data is clipped or too low, the recorder adjusts the gain of the amplifier circuits to accurately acquire subsequent components of the lightning induced transients.

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

    PubMed Central

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

    2014-01-01

    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

  11. High voltage power Schottky diodes

    NASA Technical Reports Server (NTRS)

    Cordes, L. F.; Garfinkel, M.

    1974-01-01

    Calculations of the low frequency rectification efficiency of power Schottky diodes show that silicon Schottky rectifiers have lower losses than silicon p-n junctions for all voltage applications up to approximately 150 volts. These calculations are presented. Large area Schottky diodes have been fabricated which exhibit near ideal reverse leakage at 100 C out to approximately 100 volts and which have current capability of 100 A. Fabrication details and performance data are presented.

  12. Analytical Investigation of an Adaptive Flight-Control System Using a Sinusoidal Test Signal

    NASA Technical Reports Server (NTRS)

    Harris, Jack E.

    1961-01-01

    An analytical study was made of an adaptive flight-control system which measures vehicle response to small-amplitude control-surface deflections produced by a sinusoidal test signal. Changes in the response to this signal are related to environmental changes,, and the system is continuously altered to maintain this response equal to a preselected value. The system is suitable for use in high-performance aircraft and missiles and requires only the addition of a signal generator and a logic circuit consisting of a filter-rectifier network and a comparator-integrator network to a basic command-control system. Thus, it presents a relatively simple approach to the problem. The effects on system performance of variation in flight condition, system-gain level, test-signal frequency, and sensor location are included in the analysis. Longitudinal control of a high-performance research aircraft over flight conditions ranging from landing approach to a Mach number of 5.8 at an altitude of 150,000 feet, and longitudinal control of a four-stage solid-fuel missile including the first bending mode over the atmospheric portion of a launch trajectory constituted the basis for the analytical study. Results of an analog-computer study using time-varying coefficients are presented to compare the control obtained with the adaptive system with-that obtained with a fixed-gain system during the atmospheric portion of a missile launch trajectory. The system has demonstrated an ability to maintain satisfactory vehicle control-system stability over wide ranges of environmental change.

  13. VOLTAGE-CONTROLLED TRANSISTOR OSCILLATOR

    DOEpatents

    Scheele, P.F.

    1958-09-16

    This patent relates to transistor oscillators and in particular to those transistor oscillators whose frequencies vary according to controlling voltages. A principal feature of the disclosed transistor oscillator circuit resides in the temperature compensation of the frequency modulating stage by the use of a resistorthermistor network. The resistor-thermistor network components are selected to have the network resistance, which is in series with the modulator transistor emitter circuit, vary with temperature to compensate for variation in the parameters of the transistor due to temperature change.

  14. Dynamical Coulomb blockade of tunnel junctions driven by alternating voltages

    NASA Astrophysics Data System (ADS)

    Grabert, Hermann

    2015-12-01

    The theory of the dynamical Coulomb blockade is extended to tunneling elements driven by a time-dependent voltage. It is shown that, for standard setups where an external voltage is applied to a tunnel junction via an impedance, time-dependent driving entails an excitation of the modes of the electromagnetic environment by the applied voltage. Previous approaches for ac driven circuits need to be extended to account for the driven bath modes. A unitary transformation involving also the variables of the electromagnetic environment is introduced which allows us to split off the time dependence from the Hamiltonian in the absence of tunneling. This greatly simplifies perturbation-theoretical calculations based on treating the tunneling Hamiltonian as a perturbation. In particular, the average current flowing in the leads of the tunnel junction is studied. Explicit results are given for the case of an applied voltage with a constant dc part and a sinusoidal ac part. The connection with standard dynamical Coulomb blockade theory for constant applied voltage is established. It is shown that an alternating voltage source reveals significant additional effects caused by the electromagnetic environment. The hallmark of the dynamical Coulomb blockade in ac driven devices is a suppression of higher harmonics of the current by the electromagnetic environment. The theory presented basically applies to all tunneling devices driven by alternating voltages.

  15. Characterization of surface dielectric barrier discharge influenced by intermediate frequency for ozone production

    NASA Astrophysics Data System (ADS)

    Abdelaziz, Ayman A.; Ishijima, Tatsuo; Seto, Takafumi; Osawa, Naoki; Wedaa, Hassan; Otani, Yoshio

    2016-06-01

    The aim of this study is to investigate the effect of the intermediate frequency (1–10 kHz) of the sinusoidal driving voltage on the characteristics of a developed surface dielectric barrier discharge (SDBD)-based reactor having spikes on its discharge electrode. Moreover, its influence on the production of ozone and nitrogen oxide byproducts is evaluated. The results show that SDBD is operated in the filamentary mode at all the frequencies. Nevertheless, the pulses of the discharge current at high frequencies are much denser and have higher amplitudes than those at low frequencies. The analysis of the power consumed in the reactor shows that a small portion of the input power is dissipated in the dielectric material of SDBD source, whereas the major part of the power is consumed in the plasma discharge. The results of the ozone production show that higher frequencies have a slightly adverse effect on the ozone production at relatively high energy density values, where the ozone concentration is slightly decreased when the frequency is increased at the same energy density. The temperature of the discharge channels and gas is not a crucial factor for the decomposition of ozone in this reactor, while the results of the measurements of nitrogen oxides characteristics indicate that the formation of NO and NO2 has a significant adverse effect on the production efficiency of ozone due to their oxidation to another nitrogen oxides and their catalytic effect.

  16. Hepatic sinusoids in liver injury, inflammation, and fibrosis: new pathophysiological insights.

    PubMed

    Greuter, Thomas; Shah, Vijay H

    2016-06-01

    Changes of hepatic sinusoids are crucial in the pathogenesis of liver cirrhosis and portal hypertension. Liver injury leads to distinct morphological abnormalities such as loss of sinusoidal fenestration, vasoconstriction, and angiogenesis as well as molecular changes. Communication between the two key cells in this hepatic microenvironment-hepatic stellate cells (HSC) and sinusoidal endothelial cells (SEC)-has been studied for many years and several canonical pathways have been elucidated, such as decreased eNOS activity or increased PDGF and TGF-β production leading to activation and migration of HSC. In recent studies, alternative pathways of intercellular communication in liver diseases have been described such as cell-derived extracellular vesicles called exosomes, which deliver cell compounds to their target cells. Moreover, such extracellular vesicles may link injury to inflammation in alcoholic hepatitis. While inflammation leading to liver fibrosis has been studied in detail, in some circumstances pathways other than the known canonical inflammatory pathways may contribute to hepatic fibrogenesis. For example, in congestive hepatopathy, sinusoidal dilatation and fibrosis have been shown to be mediated by non-inflammatory mechanisms and associated with sinusoidal thrombi. A recently developed murine model further enables experimental studies of this disease entity. Increasing knowledge about these alternative disease pathways in liver injury, inflammation, and fibrosis may reveal possible target molecules for future therapies. This article builds upon a seminar given at the recent 3rd JSGE International Topic Conference in Sendai, Japan, and reviews the areas outlined above. PMID:26939970

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

    NASA Astrophysics Data System (ADS)

    Chen, Huang; Wang, Jin-Jun

    2014-06-01

    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.

  18. Automatic voltage imbalance detector

    DOEpatents

    Bobbett, Ronald E.; McCormick, J. Byron; Kerwin, William J.

    1984-01-01

    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.

  19. Experimental comparison of aperiodic sinusoidal fringes and phase-shifted sinusoidal fringes for high-speed three-dimensional shape measurement

    NASA Astrophysics Data System (ADS)

    Heist, Stefan; Kühmstedt, Peter; Tünnermann, Andreas; Notni, Gunther

    2016-02-01

    Stereo vision-based triangulation systems are commonly used to reconstruct the three-dimensional surface shape of objects. In order to increase accuracy, they typically contain a projector which projects a sequence of patterns onto the object's surface. However, in spite of a considerable demand to measure dynamic processes, such systems are often limited to static objects. In order to enhance their speed, apart from fast cameras and projection systems, it is useful to use pattern sequences as short as possible. In this contribution, we experimentally compare two different illumination approaches, aperiodic sinusoidal fringes and phase-shifted sinusoidal fringes, with regard to the achievable point cloud completeness and accuracy depending on the pattern parameters and sequence length.

  20. Mixed voltage VLSI design

    NASA Technical Reports Server (NTRS)

    Panwar, Ramesh; Rennels, David; Alkalaj, Leon

    1993-01-01

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

  1. Low distortion automatic phase control circuit. [voltage controlled phase shifter

    NASA Technical Reports Server (NTRS)

    Hauge, G.; Pederson, C. W. (Inventor)

    1974-01-01

    A voltage controlled phase shifter is rendered substantially harmonic distortion free over a large dynamic input range by employing two oppositely poled, equally biased varactor diodes as the voltage controlled elements which adjust the phase shift. Control voltages which affect the bias of both diodes equally are used to adjust the phase shift without increasing distortion. A feedback stabilized phase shifter is rendered substantially frequency independent by employing a phase detector to control the phase shift of the voltage controlled phase shifter.

  2. In situ analysis of texture development from sinusoidal stress at high pressure and temperature

    SciTech Connect

    Li, Li; Weidner, Donald J.

    2015-12-15

    Here, we present a new experimental protocol to investigate the relationship between texture, plastic strain, and the mechanisms of plastic deformation at high pressure and temperature. The method utilizes synchrotron X-ray radiation as the probing tool, coupled with a large-volume high pressure deformation device (D-DIA). The intensity of X-ray diffraction peaks within the spectrum of the sample is used for sampling texture development in situ. The unique feature of this study is given by the sinusoidal variation of the intensity when a sinusoidal strain is applied to the sample. For a sample of magnesium oxide at elevated pressure and temperature, we demonstrate observations that are consistent with elasto-plastic models for texture development and for diffraction-peak measurements of apparent stress. The sinusoidal strain magnitude was 3%.

  3. The Integrity bare-metal stent made by continuous sinusoid technology.

    PubMed

    Turco, Mark A

    2011-05-01

    The Integrity Coronary Stent System (Medtronic Vascular, CA, USA) is a low-profile, open-cell, cobalt-chromium-alloy advanced bare-metal iteration of the well-known Driver/Micro-Driver Coronary Stent System (Medtronic Vascular). The Integrity stent is made with a process called continuous sinusoid technology. This process allows stent construction via wrapping a single thin strand of wire around a mandrel in a sinusoid configuration, with laser fusion of adjacent crowns. The wire-forming process and fusion pattern provide the stent with a continuous preferential bending plane, intended to allow easier access to, and smoother tracking within, distal and tortuous vessels while radial strength is maintained. Continuous sinusoid technology represents innovation in the design of stent platforms and will provide a future stent platform for newer technology, including drug-eluting stent platforms, drug-filled stents and core wire stents. PMID:21542702

  4. In situ analysis of texture development from sinusoidal stress at high pressure and temperature.

    PubMed

    Li, Li; Weidner, Donald J

    2015-12-01

    Here, we present a new experimental protocol to investigate the relationship between texture, plastic strain, and the mechanisms of plastic deformation at high pressure and temperature. The method utilizes synchrotron X-ray radiation as the probing tool, coupled with a large-volume high pressure deformation device (D-DIA). The intensity of X-ray diffraction peaks within the spectrum of the sample is used for sampling texture development in situ. The unique feature of this study is given by the sinusoidal variation of the intensity when a sinusoidal strain is applied to the sample. For a sample of magnesium oxide at elevated pressure and temperature, we demonstrate observations that are consistent with elasto-plastic models for texture development and for diffraction-peak measurements of apparent stress. The sinusoidal strain magnitude was 3%. PMID:26724072

  5. Sinusoidal response of composite-material plates with material damping.

    NASA Technical Reports Server (NTRS)

    Siu, C. C.; Bert, C. W.

    1973-01-01

    A general forced-vibration analysis is presented for laminated anisotropic rectangular plates including material damping. The theory used is the laminated version of the Mindlin plate theory and includes thickness-shear flexibility and rotatory and coupling inertia. A solution is obtained by the Rayleigh-Ritz method, extended to include the energy dissipated and the work done by the excitation. The analysis is applied to prediction of the resonant frequencies and associated nodal patterns and damping ratios of the first five modes for a series of rectangular plates with free edges. The plates considered consist of unidirectional boron-fiber/epoxy composite material with respective fiber orientations of 0, 10, 30, 45, 60, and 90 deg.

  6. Effects of digital filtering on the parameters of sinusoidal tracking eye movements.

    PubMed

    Juhola, M

    1995-08-01

    In the present study linear nonrecursive (FIR) filters designed with the Hamming window and hybrid median filters were examined in connection with computer analysis of sinusoidal tracking eye movements. It is important that digital filters which do not distort sensitive properties of eye movement signals are employed in order to prevent changes caused by too strict filtering in average parameter values of eye movement signals, indicators of some otoneurological disorders. It turned out that within reasonable limits these filters are valid in filtering of sinusoidal tracking eye movement signals. PMID:8549120

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

    NASA Astrophysics Data System (ADS)

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

    2013-09-01

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

  8. Primary Liver Sinusoidal Non-Hodgkin's Lymphoma Presenting as Acute Liver Failure.

    PubMed

    Nagral, Aabha; Jhaveri, Ajay; Kalthoonical, Vilesh; Bhat, Ganapathi; Mahajan, Pravin; Borges, Anita

    2015-12-01

    We describe a case of a middle-aged woman, who presented to us with fever, anorexia, abdominal distension from a massive hepatomegaly, low hemoglobin, and acute liver failure. A liver biopsy revealed B cell non-Hodgkin's lymphoma predominantly in the sinusoids with CD10, CD20, and Bcl-2 positive on immunohistochemistry. She initially responded well to chemotherapy but succumbed 6 months later to the recurrence of disease. Sinusoidal non-Hodgkin's lymphoma of the liver should be considered in the differential diagnosis of a patient with large hepatomegaly presenting with acute liver failure. PMID:26900276

  9. Dynamic optical frequency domain reflectometry.

    PubMed

    Arbel, Dror; Eyal, Avishay

    2014-04-21

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

  10. Performance improvement of plasma actuators using asymmetric high voltage waveforms

    NASA Astrophysics Data System (ADS)

    Kotsonis, M.; Ghaemi, S.

    2012-02-01

    An experimental study is conducted on high voltage waveforms used to power plasma actuators. Shapes that present an asymmetry between the two half cycles are investigated by means of induced thrust and velocity measurements. A parametric study is performed based on thrust measurements in order to find the optimum shape within the tested range. An asymmetric waveform which is made as a combination of sinusoidal and square shapes is found to increase produced thrust by almost 30% compared with the conventional sinusoidal waveform. The asymmetric waveform is further analysed using time-resolved particle image velocimetry in order to reveal the forcing mechanism governed by the shape differences. It is shown that the shape of the waveform has a significant effect on the performance of the actuator. Push and pull events occur within the actuation period and their respective strength and duration closely correlates with the shape of the waveform. It is found that the pull event is significantly weakened for the case of the optimized asymmetric waveform in comparison with the sinusoidal shape. This effectively increases the net momentum transfer and an improvement of approximately 40% in maximum induced velocity is achieved compared with sine waveform. Power consumption due to the asymmetric waveform is marginally increased which provides a significant increase in the actuator's relative efficiency.

  11. External laser frequency stabilizer

    SciTech Connect

    Hall, J.L.; Hansch, T.W.

    1987-10-13

    A frequency transducer for controlling or modulating the frequency of a light radiation system is described comprising: a source of radiation having a predetermined frequency; an electro-optic phase modulator for receiving the radiation and for changing the phase of the radiation in proportion to an applied error voltage; an acousto-optic modulator coupled to the electro-optic modulator for shifting the frequency of the output signal of the electro-optic modulator; a signal source for providing an error voltage representing undesirable fluctuations in the frequency of the light radiation; a first channel including a fast integrator coupled between the signal source and the input circuit of the electro-optic modulator; a second channel including a voltage controlled oscillator coupled between the signal source and the acousto-optic modulator; and a network including an electronic delay circuit coupled between the first and second channels for matching the delay of the acousto-optic modulator.

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

    PubMed

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

    2015-07-01

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

  13. Time-frequency signature sparse reconstruction using chirp dictionary

    NASA Astrophysics Data System (ADS)

    Nguyen, Yen T. H.; Amin, Moeness G.; Ghogho, Mounir; McLernon, Des

    2015-05-01

    This paper considers local sparse reconstruction of time-frequency signatures of windowed non-stationary radar returns. These signals can be considered instantaneously narrow-band, thus the local time-frequency behavior can be recovered accurately with incomplete observations. The typically employed sinusoidal dictionary induces competing requirements on window length. It confronts converse requests on the number of measurements for exact recovery, and sparsity. In this paper, we use chirp dictionary for each window position to determine the signal instantaneous frequency laws. This approach can considerably mitigate the problems of sinusoidal dictionary, and enable the utilization of longer windows for accurate time-frequency representations. It also reduces the picket fence by introducing a new factor, the chirp rate α. Simulation examples are provided, demonstrating the superior performance of local chirp dictionary over its sinusoidal counterpart.

  14. Time-resolved spectroscopy of a homogeneous dielectric barrier discharge for soft ionization driven by square wave high voltage.

    PubMed

    Horvatic, Vlasta; Michels, Antje; Ahlmann, Norman; Jestel, Günter; Veza, Damir; Vadla, Cedomil; Franzke, Joachim

    2015-10-01

    Helium capillary dielectric barrier discharge driven by the square wave-shaped high voltage was investigated spatially and temporally by means of optical emission spectroscopy. The finding of the previous investigation conducted with the sinusoidal-like high voltage was confirmed, i.e., the plasma in the jet and the plasma in the capillary constitute two temporally separated events. The plasma in the jet occurs prior to the discharge in the capillary and exists only during the positive half period of the applied high voltage. The time delay of the capillary discharge with respect to the discharge in the jet depended on the high voltage, and it was between 2.4 and 8.4 μs for the voltage amplitude change in the range from 1.96 to 2.31 kV, respectively. It was found that, compared to sinusoidal-like voltage, application of the square wave high voltage results with stronger (~6 times) He line emission in the jet, which makes the latter more favorable for efficient soft ionization. The use of the square wave high voltage enabled comparison of the currents (~1 mA) flowing in the capillary during the positive and negative high voltage periods, which yielded the estimation for the charge dissipated in the atmosphere ((4 ± 20 %) × 10(-11) C) through the plasma jet. PMID:26297466

  15. Microwave integrated circuit for Josephson voltage standards

    NASA Technical Reports Server (NTRS)

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

    1980-01-01

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

  16. Utilization of HPASubC for the Identification of Sinusoid-Specific Proteins in the Liver.

    PubMed

    Anene, Divine-Favour; Rosenberg, Avi Z; Kleiner, David E; Cornish, Toby C; Halushka, Marc K

    2016-05-01

    Mass spectrometry-based proteomes of human organs and tissues are powerful tools but fail to capture protein localization and expression at the cellular level. For example, the proteome signal in liver represents the combined protein expression across diverse cellular constituents that include hepatocytes, Kupffer cells, endothelial cells, and others. We utilized HPASubC and the Human Protein Atlas (HPA) to identify the sinusoidal component of protein liver expression to further subset and organize this homogeneous signal. We evaluated 51 109 liver images covering 13 197 proteins from the HPA and discovered 1054 proteins that were exclusive to sinusoidal cells. Sinusoidal staining patterns were identified in a Kupffer cell (n = 247), endothelial cell (n = 358), or lymphocyte (n = 86) specific pattern. Two-hundred and thirty-nine of these proteins were not present in the NextProt or Human Proteome Map liver data sets, potentially expanding our knowledge of the liver proteome. We additionally demonstrate unique endothelial cell expression patterns that distinguish between portal vein, hepatic artery, capillary sinusoids, and central vein regions. These findings significantly improve our understanding of the liver proteome with insight into the endothelial complexity across the hepatic vascular network. PMID:27005832

  17. 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...

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

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

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

  19. Oxaliplatin-induced sinusoidal obstruction syndrome mimicking metastatic colon cancer in the liver

    PubMed Central

    CHOI, JUNG-HYE; WON, YOUNG-WOONG; KIM, HYUN SUNG; OH, YOUNG-HA; LIM, SANGHYEOK; KIM, HAN-JOON

    2016-01-01

    Oxaliplatin is an effective chemotherapeutic agent for the treatment of colorectal cancer; however, it may cause liver injury, particularly sinusoidal obstruction syndrome (SOS). Although SOS does not usually present with focal lesions on radiological images, the present study describes the case of a 22-year-old woman with oxaliplatin-induced SOS mimicking metastatic colon cancer in the liver. An abdominal computed tomography revealed a novel 1 cm, low-density lesion in segment 1 of the liver following the administration of the fourth round of oxaliplatin-based adjuvant chemotherapy for stage III colon cancer. Since the lesion was indistinguishable from metastasis, even with detailed imaging studies, including magnetic resonance imaging and positron emission tomography-computed tomography, an isolated caudate lobectomy was planned. The cut surface of the resected liver showed a localized reddish congested lesion measuring 1.4 cm in diameter. The adjacent hepatic parenchyma also demonstrated diffuse sinusoidal congestion with a nutmeg-like appearance. Histologically, the lesion exhibited severe sinusoidal congestion with peliosis hepatis-like features. The widened sinusoidal space was outlined by markedly attenuated hepatic cords and filled with erythrocytes. The final diagnosis was oxaliplatin-induced SOS. The patient recovered completely and was relapse-free at the time of writing. PMID:27073565

  20. The influence of large deformations on mechanical properties of sinusoidal ligament structures

    NASA Astrophysics Data System (ADS)

    Strek, Tomasz; Jopek, Hubert; Wojciechowski, Krzysztof W.

    2016-05-01

    Studies of mechanical properties of materials, both theoretical and experimental, usually deal with linear characteristics assuming a small range of deformations. In particular, not much research has been published devoted to large deformations of auxetic structures – i.e. structures exhibiting negative Poisson’s ratio. This paper is focused on mechanical properties of selected structures that are subject to large deformations. Four examples of structure built of sinusoidal ligaments are studied and for each geometry the impact of deformation size and geometrical parameters on the effective mechanical properties of these structures are investigated. It is shown that some of them are auxetic when compressed and non-auxetic when stretched. Geometrical parameters describing sinusoidal shape of ligaments strongly affect effective mechanical properties of the structure. In some cases of deformation, the increase of the value of amplitude of the sinusoidal shape decreases the effective Poisson’s ratio by 0.7. Therefore the influence of geometry, as well as the arrangement of ligaments allows for smart control of mechanical properties of the sinusoidal ligament structure being considered. Given the large deformation of the structure, both a linear elastic material model, and a hyperelastic Neo-Hookean material model are used.

  1. A closed-loop system for frequency tracking of piezoresistive cantilever sensors

    NASA Astrophysics Data System (ADS)

    Wasisto, Hutomo Suryo; Zhang, Qing; Merzsch, Stephan; Waag, Andreas; Peiner, Erwin

    2013-05-01

    A closed loop circuit capable of tracking resonant frequencies for MEMS-based piezoresistive cantilever resonators is developed in this work. The proposed closed-loop system is mainly based on a phase locked loop (PLL) circuit. In order to lock onto the resonant frequency of the resonator, an actuation signal generated from a voltage-controlled oscillator (VCO) is locked to the phase of the input reference signal of the cantilever sensor. In addition to the PLL component, an instrumentation amplifier and an active low pass filter (LPF) are connected to the system for gaining the amplitude and reducing the noise of the cantilever output signals. The LPF can transform a rectangular signal into a sinusoidal signal with voltage amplitudes ranging from 5 to 10 V which are sufficient for a piezoactuator input (i.e., maintaining a large output signal of the cantilever sensor). To demonstrate the functionality of the system, a self-sensing silicon cantilever resonator with a built-in piezoresistive Wheatstone bridge is fabricated and integrated with the circuit. A piezoactuator is utilized for actuating the cantilever into resonance. Implementation of this closed loop system is used to track the resonant frequency of a silicon cantilever-based sensor resonating at 9.4 kHz under a cross-sensitivity test of ambient temperature. The changes of the resonant frequency are interpreted using a frequency counter connected to the system. From the experimental results, the temperature sensitivity and coefficient of the employed sensor are 0.3 Hz/°C and 32.8 ppm/°C, respectively. The frequency stability of the system can reach up to 0.08 Hz. The development of this system will enable real-time nanoparticle monitoring systems and provide a miniaturization of the instrumentation modules for cantilever-based nanoparticle detectors.

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

    ERIC Educational Resources Information Center

    Nagasawa, Yoshinori; Demura, Shinichi

    2010-01-01

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

  3. The strength of the reflex response to sinusoidal stretch of monkey jaw closing muscles during voluntary contraction.

    PubMed

    Goodwin, G M; Hoffman, D; Luschei, E S

    1978-06-01

    1. Rhesus monkeys were trained to exert steady biting forces of 3--60 N for 1--2 sec. This behaviour was well maintained while sinusoidal or step opening and closing movements were imposed on the jaw. 2. The amplitude of the force modulation during sinusoidal stretching was divided by the amplitude of movement to obtain the magnitude of stiffness. This estimate was made at frequencies from 2 to 50 Hz at amplitudes of 100 and 500 micrometer (half the peak-to-peak movement at the incisors). 3. Peak magnitudes of stiffness were seen with frequencies of 8--15 Hz when the amplitude of movement was small; there was a great deal of variation between individual animals. This variation was most striking with mean forces of 25--35 N. The stiffness was greatest in animals that showed considerable spontaneous tremor, and the highest levels of stiffness were often recorded with frequencies near which tremor amplitude was large. A marked phase lag in the force response was often seen during small amplitude stretching at 8--30 Hz. 4. Estimates of stiffness for larger amplitude (500 micrometer) stretching showed less variation; the magnitude of stiffness showed maximum values below 10 Hz and a minimum at 15--30 Hz. Force always showed a phase lead on position although this lead became small in the frequency range where with smaller movement there had been phase lags. The magnitude of stiffness increased with increasing mean force. 5. Bilateral electrolytic lesions were made in the brain stems of three animals; they reduced by over 95% the expected number of cells in the mesencephalic nucleus of the fifth cranial nerve on either side. These lesions interrupted the afferent pathway for the stretch reflex and so abolished excitatory electromyogram (e.m.g.) responses to step stretches of the jaw closing muscles. 6. Such reflex responses as persisted after the lesions were small and inhibitory. E.m.g. silences followed both step stretch and release; the response to release was a 'load compensation' that could not be attributed to spindle afferents. 7. After the lesions the responses to movements of 100 micrometer showed neither negative values for the phase nor marked peaks in the stiffness magnitude at low frequencies; these features therefore take origin in the action of the stretch reflex. The stiffness that was measured after the lesions may be attributed to the non-reflex components resisting stretch, particularly to the properties of the contracting muscles. Thus, the phase of the force response was markedly advanced at all frequencies and the stiffness seen for 100 micrometer was similar to that for 500 micrometer. Stiffness increased with increasing mean force, as before surgery. 8. Vector subtraction of the stiffness seen at each frequency after interrupting the stretch reflex from that seen before doing so gave a quantitative estimate of the strength of the stretch reflex. The reflex activity calculated in this way showed attenuation and progressive phase lag as the frequency increased above 10 Hz... PMID:97378

  4. Linear theory of frequency pulling in gyrotrons

    NASA Astrophysics Data System (ADS)

    Nusinovich, Gregory S.; Luo, Li; Liu, Pu-kun

    2016-05-01

    The effect of the electron beam on the gyrotron operating frequency (the frequency pulling) is studied analytically in the framework of the linear (or small-signal) theory. The theory is applicable for gyrotrons operating at any cyclotron harmonics and in modes with arbitrary axial structures. The present consideration is limited to cases of operation at the fundamental cyclotron resonance and the second harmonic; also two specific axial profiles of the resonator modes are analyzed: the constant and the sinusoidal distributions. In the case of the sinusoidal distribution, we considered the operation in modes with one, two, and three axial variations. It is shown how to use the theory developed for analyzing the frequency tunability due to the frequency pulling effect in a gyrotron with specified parameters of the electron beam.

  5. High voltage RF feedthrough bushing

    DOEpatents

    Grotz, Glenn F.

    1984-01-01

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

  6. Induction motor control system with voltage controlled oscillator circuit

    NASA Technical Reports Server (NTRS)

    Nola, F. J.; Currie, J. R.; Reid, H., Jr. (Inventor)

    1973-01-01

    A voltage controlled oscillator circuit is reported in which there are employed first and second differential amplifiers. The first differential amplifier, being employed as an integrator, develops equal and opposite slopes proportional to an input voltage, and the second differential amplifier functions as a comparator to detect equal amplitude positive and negative selected limits and provides switching signals which gate a transistor switch. The integrating differential amplifier is switched between charging and discharging modes to provide an output of the first differential amplifier which upon the application of wave shaping provides a substantially sinusoidal output signal. A two phased version with a second integrator provides a second 90 deg phase shifted output for induction motor control.

  7. Moderately nonlinear diffuse-charge dynamics under an ac voltage

    NASA Astrophysics Data System (ADS)

    Stout, Robert F.; Khair, Aditya S.

    2015-09-01

    The response of a symmetric binary electrolyte between two parallel, blocking electrodes to a moderate amplitude ac voltage is quantified. The diffuse charge dynamics are modeled via the Poisson-Nernst-Planck equations for a dilute solution of point-like ions. The solution to these equations is expressed as a Fourier series with a voltage perturbation expansion for arbitrary Debye layer thickness and ac frequency. Here, the perturbation expansion in voltage proceeds in powers of Vo/(kBT /e ) , where Vo is the amplitude of the driving voltage and kBT /e is the thermal voltage with kB as Boltzmann's constant, T as the temperature, and e as the fundamental charge. We show that the response of the electrolyte remains essentially linear in voltage amplitude at frequencies greater than the RC frequency of Debye layer charging, D /λDL , where D is the ion diffusivity, λD is the Debye layer thickness, and L is half the cell width. In contrast, nonlinear response is predicted at frequencies below the RC frequency. We find that the ion densities exhibit symmetric deviations from the (uniform) equilibrium density at even orders of the voltage amplitude. This leads to the voltage dependence of the current in the external circuit arising from the odd orders of voltage. For instance, the first nonlinear contribution to the current is O (Vo3) which contains the expected third harmonic but also a component oscillating at the applied frequency. We use this to compute a generalized impedance for moderate voltages, the first nonlinear contribution to which is quadratic in Vo. This contribution predicts a decrease in the imaginary part of the impedance at low frequency, which is due to the increase in Debye layer capacitance with increasing Vo. In contrast, the real part of the impedance increases at low frequency, due to adsorption of neutral salt from the bulk to the Debye layer.

  8. Large endolymphatic potentials from low-frequency and infrasonic tones in the guinea pig.

    PubMed

    Salt, Alec N; Lichtenhan, Jeffery T; Gill, Ruth M; Hartsock, Jared J

    2013-03-01

    Responses of the ear to low-frequency and infrasonic sounds have not been extensively studied. Understanding how the ear responds to low frequencies is increasingly important as environmental infrasounds are becoming more pervasive from sources such as wind turbines. This study shows endolymphatic potentials in the third cochlear turn from acoustic infrasound (5 Hz) are larger than from tones in the audible range (e.g., 50 and 500 Hz), in some cases with peak-to-peak amplitude greater than 20 mV. These large potentials were suppressed by higher-frequency tones and were rapidly abolished by perilymphatic injection of KCl at the cochlear apex, demonstrating their third-turn origins. Endolymphatic iso-potentials from 5 to 500 Hz were enhanced relative to perilymphatic potentials as frequency was lowered. Probe and infrasonic bias tones were used to study the origin of the enhanced potentials. Potentials were best explained as a saturating response summed with a sinusoidal voltage (Vo), that was phase delayed by an average of 60° relative to the biasing effects of the infrasound. Vo is thought to arise indirectly from hair cell activity, such as from strial potential changes caused by sustained current changes through the hair cells in each half cycle of the infrasound. PMID:23464026

  9. Voltage verification unit

    DOEpatents

    Martin, Edward J.

    2008-01-15

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

  10. Electron heating in capacitively coupled plasmas revisited: single and multi-frequency discharges

    NASA Astrophysics Data System (ADS)

    Lafleur, Trevor

    2013-09-01

    Using particle-in-cell (PIC) simulations, we re-analyse the mechanism of electron heating in low pressure capacitively coupled plasmas (CCPs). After equilibrium has been reached in the simulations, spatio-temporal moments of the electron distribution function are taken within the rf cycle, and from this the density, current, pressure, and momentum loss due to collisions, of the electrons is found in the discharge. With these moments we then reconstruct each term in the electron fluid mechanical energy conservation equation, so as to explicitly analyse the power deposition process. We perform simulations for both single frequency sinusoidal discharges, and also for more recent multi-frequency, or ``tailored voltage waveform'' driven discharges. The single frequency (13.56 MHz) simulations are modelled on the original experiments in Argon performed by Godyak, showing the transition from a bi-Maxwellian distribution function at low pressure (below 200 mTorr) to a Druyvestyen-type distribution at high pressures (above 400 mTorr). The results of the PIC moment analysis shows that only two terms in the fluid conservation equation contribute a net power deposition: a term accounting for collisional power absorption, and a term accounting for pressure heating. The latter term is dominant at low pressures, while the former is dominant at higher pressures. We find however that the collisional heating is almost always significant, and even at the lowest pressure, accounts for about 40% of the total power absorption. By comparing the electron momentum loss due to collisions with that usually used in analytical sheath models, we find a significant difference at low pressures, which cannot be explained by conventional local kinetic theories based on the two-term expansion of the Boltzmann equation. The moment analysis is repeated for the multi-frequency discharges, where we obtain similar results: collisional power absorption is always observed to be significant, even at the lowest pressures simulated (20 mTorr). However the generation of a bias voltage due to the electrical asymmetry effect, and consequently the unequal division of the sheath voltages, causes high frequency oscillations to develop in the plasma at frequencies more than an order of magnitude higher than the applied rf frequencies. These so-called nonlinear plasma series resonance oscillations are found to enhance both the collisional and pressure heating, and for sufficiently large applied voltages, an additional heating mechanism is identified associated with the electron inertial terms in the conservation equation.

  11. Voltage Effects on a Commercial Plasma Globe

    NASA Astrophysics Data System (ADS)

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

    2013-10-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    A test bench for studying two-electrode spark gaps rated at a voltage of 300 kV and a pulse repetition rate of up to 10 Hz and operating in air at elevated pressure. The typical time of pulse charging of a capacitive storage in the bench equals about 100 μs. 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.

  13. Investigating the dependence of the temperature of high-intensity discharge (HID) lamp electrodes on the operating frequency by pyrometric measurements

    NASA Astrophysics Data System (ADS)

    Reinelt, J.; Westermeier, M.; Ruhrmann, C.; Bergner, A.; Awakowicz, P.; Mentel, J.

    2011-03-01

    Phase-resolved temperature distributions are determined along a rod-shaped tungsten electrode, by which an ac arc is operated within a model lamp filled with argon. Switched dc and sinusoidal currents are applied with amplitudes of several amperes and operating frequencies being varied between 10 Hz and 10 kHz. The temperature is deduced from the grey body radiation of the electrode being recorded with a spectroscopic measuring system. Phase-resolved values of the electrode tip temperature Ttip and of the power input Pin are determined comparing the measured temperature distributions with the integral of the one-dimensional heat balance with these parameters as integration constants. They are supplemented by phase-resolved measurements of the sum of cathode and anode fall called the electrode sheath voltage. If a switched dc current is applied it is found that both quantities are within the cathodic phase only marginally higher than for a cathode being operated with a dc current. Ttip and Pin start to decrease for low currents and to increase for high currents at the beginning of the anodic phase. But with increasing operating frequency the deviations from the cathodic phase are reduced until they cannot be resolved for frequencies of several kHz. A more pronounced modulation, but the same tendencies, is observed with a sinusoidal current waveform. For 10 kHz a diffuse arc attachment with an almost phase-independent electrode tip temperature, which deviates only marginally from that of a dc cathode, and an electrode sheath voltage proportional to the arc current is established with both current waveforms.

  14. Voltage balanced multilevel voltage source converter system

    DOEpatents

    Peng, Fang Zheng; Lai, Jih-Sheng

    1997-01-01

    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. Voltage balanced multilevel voltage source converter system

    DOEpatents

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

    1997-07-01

    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.

  16. Building Sinusoids

    ERIC Educational Resources Information Center

    Landers, Mara G.

    2013-01-01

    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…

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

    NASA Astrophysics Data System (ADS)

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

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

  18. Full-range Fourier domain polarization-sensitive optical coherence tomography using sinusoidal phase modulation

    NASA Astrophysics Data System (ADS)

    Chen, Yan; Wang, Xiangzhao; Li, Zhongliang; Nan, Nan; Guo, Xin

    2014-09-01

    We present a full-range Fourier domain polarization-sensitive optical coherence tomography technique which is able to obtain images of retardance, fast optical axis and intensity of sample. In this technique, the sinusoidal phase modulation is introduced into the spectral interferograms while the probe beam scans over the sample (B-scan). Then the complex horizontal and vertical signals are reconstructed by demodulation. By the Fourier transformation of the two interferograms, the full range images are obtained. Herein, the typical linear phase modulation is modified to sinusoidal phase modulation, which improves the system tolerance of sample movements and avoids sensitivity fall-off along the transverse scan. Furthermore, the images are obtained through the recombination of the horizontal and vertical polarization beam components acquired by a single camera, which avoids the problems of synchronous control and alignments in the situation of two cameras.

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

    SciTech Connect

    Kubota, Yoshiaki; Takubo, Keiyo; Suda, Toshio

    2008-02-08

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

  20. Femtosecond strong-field quantum control with sinusoidally phase-modulated pulses

    SciTech Connect

    Wollenhaupt, M.; Praekelt, A.; Sarpe-Tudoran, C.; Liese, D.; Bayer, T.; Baumert, T.

    2006-06-15

    The quantum control of the ionization of potassium atoms using shaped intense femtosecond laser pulses is investigated. We use sinusoidal phase modulation as a prototype for complex shaped pulses to investigate the physical mechanism of the strong-field quantum control by shaped femtosecond light fields. The influence of all parameters characterizing the sinusoidal phase modulation on strong-field-induced dynamics is studied systematically in experiment and theory. Our results are interpreted in terms of the selective population of dressed states (SPODS) which gives a natural physical picture of the dynamics in intense laser fields. We show that modulated femtosecond pulses in combination with photoelectron spectroscopy are a versatile tool to prepare and to probe SPODS. The decomposition of the excitation and ionization process induced by shaped pulses into elementary physically transparent steps is discussed.

  1. 15th International Symposium on Cells of the Hepatic Sinusoid, 2010

    PubMed Central

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

    2015-01-01

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

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

    PubMed

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

    2013-07-15

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

  3. Bouncing ball dynamics: Simple model of motion of the table and sinusoidal motion

    NASA Astrophysics Data System (ADS)

    Okniński, Andrzej; Radziszewski, Bogusław

    2014-10-01

    Nonlinear dynamics of a bouncing ball moving vertically in a gravitational field and colliding with a moving limiter is considered and the Poincar\\'e map, describing evolution from an impact to the next impact, is described. Displacement of the table is approximated in one period by four cubic polynomials. Results obtained for this model are used to elucidate dynamics of the standard model of bouncing ball with sinusoidal motion of the limiter.

  4. Simple, fast and accurate eight points amplitude estimation method of sinusoidal signals for DSP based instrumentation

    NASA Astrophysics Data System (ADS)

    Vizireanu, D. N.; Halunga, S. V.

    2012-04-01

    A simple, fast and accurate amplitude estimation algorithm of sinusoidal signals for DSP based instrumentation is proposed. It is shown that eight samples, used in two steps, are sufficient. A practical analytical formula for amplitude estimation is obtained. Numerical results are presented. Simulations have been performed when the sampled signal is affected by white Gaussian noise and when the samples are quantized on a given number of bits.

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

    NASA Technical Reports Server (NTRS)

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

    2006-01-01

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

  6. Low voltage to high voltage level shifter and related methods

    NASA Technical Reports Server (NTRS)

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

    2006-01-01

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

  7. Motion stability analysis of non-sinusoidal oscillation of mold driven by servomotor

    NASA Astrophysics Data System (ADS)

    Yao, Yunfeng; Li, Junxia; Fang, Yiming

    2015-11-01

    The investments of the electro-hydraulic servo system of the mold non-sinusoidal oscillator are great, the modification ratio of the mechanical type is unable to be adjusted online, and some continuous casters suffer from server resonance during the casting. A mold non-sinusoidal oscillation mechanism driven by servomotor is proposed and the prototype is produced in the lab, the investment is low and the modification ratio is can be adjusted online, and the stability problem is studied. At first the dynamics model of the servomotor non-sinusoidal oscillation is established, and the kinematics differential function is deduced. Furthermore, based on the harmonic balance method, the eigenvalues of the system are solved; the criterion of the stability of the system is put forward. In addition, the eigenvalues and harmonic with different oscillating parameters are analyzed. Analytical results show that the real parts of the eigenvalues are positive, the system will be unstable, and the resonance will occur when the positive real parts of the eigenvalues are extremum. A foundation is established for solving the running smooth problem and next application of this mechanism.

  8. Robust audio watermark method using sinusoid patterns based on pseudo-random sequences

    NASA Astrophysics Data System (ADS)

    Liu, Zheng; Kobayashi, Yoshiyuki; Sawato, Shusaku; Inoue, Akira

    2003-06-01

    In recent years, the spread spectrum watermarking technology has become the most promising technique that not only widely used for still image and video watermarking, but also used for audio watermarking. However, some technique problems such as requiring psycho-acoustic shaping used for reducing audible noise have greatly limited the utility of spread spectrum watermarking technology in audio watermarking. In this paper, we propose a novel audio watermarking method using spread spectrum watermarking technology by which we can embed watermark audio signals inaudibly with a robust to a wide range of unintended and intended attacks. In proposed method, the watermark is represented by sinusoidal patterns consisting of sinusoids with the phase-modulated by the elements of pseudo-random sequence. We theoretically and experimentally confirmed that the sinusoidal patterns based on pseudo-random sequences keep the same correlation property of pseudo-random sequences and have the characteristics of high robustness with less noise, being easy to manipulate, and without requirement of psycho-acoustic shaping. The watermark detection is done by blind detection and the effectiveness of proposed method have been certificated by the test of STEP2001.

  9. Sensor-less pseudo-sinusoidal drive for a permanent-magnet brushless ac motor

    NASA Astrophysics Data System (ADS)

    Liu, Li-Hsiang; Chern, Tzuen-Lih; Pan, Ping-Lung; Huang, Tsung-Mou; Tsay, Der-Min; Kuang, Jao-Hwa

    2012-04-01

    The precise rotor-position information is required for a permanent-magnet brushless ac motor (BLACM) drive. In the conventional sinusoidal drive method, either an encoder or a resolver is usually employed. For position sensor-less vector control schemes, the rotor flux estimation and torque components are obtained by complicated coordinate transformations. These computational intensive methods are susceptible to current distortions and parameter variations. To simplify the method complexity, this work presents a sensor-less pseudo-sinusoidal drive scheme with speed control for a three-phase BLACM. Based on the sinusoidal drive scheme, a floating period of each phase current is inserted for back electromotive force detection. The zero-crossing point is determined directly by the proposed scheme, and the rotor magnetic position and rotor speed can be estimated simultaneously. Several experiments for various active angle periods are undertaken. Furthermore, a current feedback control is included to minimize and compensate the torque fluctuation. The experimental results show that the proposed method has a competitive performance compared with the conventional drive manners for BLACM. The proposed scheme is straightforward, bringing the benefits of sensor-less drive and negating the need for coordinate transformations in the operating process.

  10. Discrimination of real and virtual surfaces with sinusoidal and triangular gratings using the fingertip and stylus.

    PubMed

    Kocsis, M B; Cholewiak, S A; Traylor, R M; Adelstein, B D; Hirleman, E Daniel; Tan, H Z

    2013-01-01

    Two-interval two-alternative forced-choice discrimination experiments were conducted separately for sinusoidal and triangular textured surface gratings from which amplitude (i.e., height) discrimination thresholds were estimated. Participants (group sizes: n = 4 to 7) explored one of these texture types either by fingertip on real gratings (Finger real), by stylus on real gratings (Stylus real), or by stylus on virtual gratings (Stylus virtual). The real gratings were fabricated from stainless steel by an electrical discharge machining process while the virtual gratings were rendered via a programmable force-feedback device. All gratings had a 2.5-mm spatial period. On each trial, participants compared test gratings with 55, 60, 65, or 70 μm amplitudes against a 50-μm reference. The results indicate that discrimination thresholds did not differ significantly between sinusoidal and triangular gratings. With sinusoidal and triangular data combined, the average (mean + standard error) for the Stylus-real threshold (2.5 ± 0.2 μm) was significantly smaller (p <; 0.01) than that for the Stylus-virtual condition (4.9 ± 0.2 μm). Differences between the Finger-real threshold (3.8 ± 0.2 μm) and those from the other two conditions were not statistically significant. Further studies are needed to better understand the differences in perceptual cues resulting from interactions with real and virtual gratings. PMID:24808302

  11. High Voltage TAL Performance

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

    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.

  12. Automatic ac/dc thermal voltage converter and ac voltage calibration system

    NASA Astrophysics Data System (ADS)

    Lentner, K. J.; Flach, D. R.; Bell, B. A.

    1984-11-01

    An automatic ac/dc difference calibration system is described which uses direct measurement of thermoelement emfs. In addition to ac/dc difference testing, the system can be used to measure some important characteristics of thermoelements, as well as to calibrate ac voltage calibrators and precision voltmeters. The system operates over a frequency range from 20 Hz to 100 kHz, covering the voltage range from 0.5 V to 1 kv. For all voltages the total measurement uncertainties expected (including the uncertainty of the specific reference thermal converters used) were 50 parts per million (ppm) at frequencies from 20 Hz to 20 kHz, inclusive, and 100 ppm at higher frequencies up to 100 kHz.

  13. Analytical model for the radio-frequency sheath

    NASA Astrophysics Data System (ADS)

    Czarnetzki, Uwe

    2013-12-01

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

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

    SciTech Connect

    Peng, Fang Zheng |; Lai, Jih-Sheng; McKeever, J.; VanCoevering, J.

    1995-09-01

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

  15. High voltage DC power supply

    DOEpatents

    Droege, T.F.

    1989-12-19

    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.

  16. High voltage DC power supply

    DOEpatents

    Droege, Thomas F.

    1989-01-01

    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.

  17. Low-voltage gyrotrons

    SciTech Connect

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

    2013-03-15

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

  18. Circuit engineering for transformerless converters of feed-voltage level

    NASA Astrophysics Data System (ADS)

    Goriunov, A. E.

    1985-08-01

    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.

  19. An Ultra-Low Voltage Analog Front End for Strain Gauge Sensory System Application in 0.18µm CMOS

    NASA Astrophysics Data System (ADS)

    Edward, Alexander; Chan, Pak Kwong

    This paper presents analysis and design of a new ultra-low voltage analog front end (AFE) dedicated to strain sensor applications. The AFE, designed in 0.18µm CMOS process, features a chopper-stabilized instrumentation amplifier (IA), a balanced active MOSFET-C 2nd order low pass filter (LPF), a clock generator and a voltage booster which operate at supply voltage (Vdd) of 0.6V. The designed IA achieves 30dB of closed-loop gain, 101dB of common-mode rejection ratio (CMRR) at 50Hz, 80dB of power-supply rejection ratio (PSRR) at 50Hz, thermal noise floor of 53.4 nV/√Hz, current consumption of 14µA, and noise efficiency factor (NEF) of 9.7. The high CMRR and rail-to-rail output swing capability is attributed to a new low voltage realization of the active-bootstrapped technique using a pseudo-differential gain-boosting operational transconductance amplifier (OTA) and proposed current-driven bulk (CDB) biasing technique. An output capacitor-less low-dropout regulator (LDO), with a new fast start-up LPF technique, is used to regulate this 0.6V supply from a 0.8-1.0V energy harvesting power source. It achieves power supply rejection (PSR) of 42dB at frequency of 1MHz. A cascode compensated pseudo differential amplifier is used as the filter's building block for low power design. The filter's single-ended-to-balanced converter is implemented using a new low voltage amplifier with two-stage common-mode cancellation. The overall AFE was simulated to have 65.6dB of signal-to-noise ratio (SNR), total harmonic distortion (THD) of less than 0.9% for a 100Hz sinusoidal maximum input signal, bandwidth of 2kHz, and power consumption of 51.2µW. Spectre RF simulations were performed to validate the design using BSIM3V3 transistor models provided by GLOBALFOUNDRIES 0.18µm CMOS process.

  20. Silicon-Germanium Voltage-Controlled Oscillator at 105 GHz

    NASA Technical Reports Server (NTRS)

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

    2011-01-01

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

  1. Dynamical response of the sinusoidally perturbed electrodissolution/passivation of iron in sulfuric acid solutions: Entrainment, spike generation, and quasiperiodicity.

    PubMed

    Karantonis, Antonis; Pagitsas, Michael; Sazou, Dimitra

    1993-04-01

    The iron/sulfuric acid (Fe/2 M H(2)SO(4)) system exhibits periodic current oscillations of relaxation type within the potential transition region formed between the active and passive states of the iron electrode when it is polarized in the 2 M sulfuric acid solution. In the present work the dynamical response of the Fe/2 M H(2)SO(4) electrochemical oscillator is investigated when the applied potential at the iron electrode is sinusoidally perturbed. The behavior of the periodically perturbed Fe/2 M H(2)SO(4) oscillator differs significantly from the response of other forced oscillators, as the potential amplitude E(p) and the frequency ratio omega(p)/omega(0) vary. The omega(p) and omega(0) are the angular frequencies of the perturbed applied potential and the unperturbed oscillator, respectively. A special feature of its response is the appearance of a number of spikes, generated within the passive section of a periodic oscillatory cycle for omega(p)/omega(0)<2.9, for periods of the autonomous oscillator T(0) greater, similar 3 s. The number of the generated spikes depends on the amplitude and frequency of the perturbed applied potential as well as on the period of the autonomous oscillator. Spikes are not generated for omega(p)/omega(0)=1 and the system is harmonically entrained by the forcing frequency. However, when the system is subharmonically entrained for omega(p)/omega(0) close to 2, spike generation does occur. By increasing the perturbation frequency for omega(p)/omega(0) greater, similar 2.9 and T(0) greater, similar 3 s, or by decreasing the autonomous period for T(0)<3 s and all the omega(p)/omega(0)<2.9 ratios, the spike generation pattern, is replaced by a quasiperiodic pattern. The dynamical response of the perturbed Fe/2 M H(2)SO(4) electrochemical oscillator is characterized by using time-delay reconstructions of the attractors, Poincare maps, and Fourier power spectra. PMID:12780033

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

    SciTech Connect

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

    2009-01-01

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

  3. High voltage pulse generator

    DOEpatents

    Fasching, George E.

    1977-03-08

    An improved high-voltage pulse generator has been provided which is especially useful in ultrasonic testing of rock core samples. An N number of capacitors are charged in parallel to V volts and at the proper instance are coupled in series to produce a high-voltage pulse of N times V volts. Rapid switching of the capacitors from the paralleled charging configuration to the series discharging configuration is accomplished by using silicon-controlled rectifiers which are chain self-triggered following the initial triggering of a first one of the rectifiers connected between the first and second of the plurality of charging capacitors. A timing and triggering circuit is provided to properly synchronize triggering pulses to the first SCR at a time when the charging voltage is not being applied to the parallel-connected charging capacitors. Alternate circuits are provided for controlling the application of the charging voltage from a charging circuit to be applied to the parallel capacitors which provides a selection of at least two different intervals in which the charging voltage is turned "off" to allow the SCR's connecting the capacitors in series to turn "off" before recharging begins. The high-voltage pulse-generating circuit including the N capacitors and corresponding SCR's which connect the capacitors in series when triggered "on" further includes diodes and series-connected inductors between the parallel-connected charging capacitors which allow sufficiently fast charging of the capacitors for a high pulse repetition rate and yet allow considerable control of the decay time of the high-voltage pulses from the pulse-generating circuit.

  4. Responses of non-eye movement central vestibular neurons to sinusoidal horizontal translation in compensated macaques after unilateral labyrinthectomy.

    PubMed

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

    2014-07-01

    After vestibular labyrinth injury, behavioral deficits partially recover through the process of vestibular compensation. The present study was performed to improve our understanding of the physiology of the macaque vestibular system in the compensated state (>7 wk) after unilateral labyrinthectomy (UL). Three groups of vestibular nucleus neurons were included: pre-UL control neurons, neurons ipsilateral to the lesion, and neurons contralateral to the lesion. The firing responses of neurons sensitive to linear acceleration in the horizontal plane were recorded during sinusoidal horizontal translation directed along six different orientations (30° apart) at 0.5 Hz and 0.2 g peak acceleration (196 cm/s(2)). This data defined the vector of best response for each neuron in the horizontal plane, along which sensitivity, symmetry, detection threshold, and variability of firing were determined. Additionally, the responses of the same cells to translation over a series of frequencies (0.25-5.0 Hz) either in the interaural or naso-occipital orientation were obtained to define the frequency response characteristics in each group. We found a decrease in sensitivity, increase in threshold, and alteration in orientation of best responses in the vestibular nuclei after UL. Additionally, the phase relationship of the best neural response to translational stimulation changed with UL. The symmetry of individual neuron responses in the excitatory and inhibitory directions was unchanged by UL. Bilateral central utricular neurons still demonstrated two-dimension tuning after UL, consistent with spatio-temporal convergence from a single vestibular end-organ. These neuronal data correlate with known behavioral deficits after unilateral vestibular compromise. PMID:24717349

  5. Device for monitoring cell voltage

    DOEpatents

    Doepke, Matthias; Eisermann, Henning

    2012-08-21

    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.

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

    PubMed

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

    2009-08-01

    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

  7. High field phenomena in polymer films and high frequency attenuation in shielded power cable

    NASA Astrophysics Data System (ADS)

    Xu, Chunchuan

    Polymer films are too thin to be characterized by guarded needle experiments and must be studied in a quasi-uniform field configuration. In such a configuration if the field is held above about 60% of the short term breakdown field, high field aging will cause the film to break down before dielectric relaxation is complete. Thus to study such films to near the short term breakdown field, film properties must be studied using a ramp voltage (˜300 V/s) up to breakdown, as is employed to characterize the statistical breakdown characteristics. An electronic system with active feedback has been developed for measuring resistive currents in polymer films up to breakdown to study the nonlinear electrical conductivity as reflected in the relaxation time as a function of electric field. Experimental results are presented and a theoretical context has been developed for the experimental results. To investigate the nonlinearity in film polarizability, a system has been designed for measuring high field capacitance up to breakdown. The system measures the capacitance by reading the capacitive current caused by a small sinusoidal signal superimposed on the high voltage DC applied to the test sample and survives high voltage breakdowns. An automatic breakdown tester has been developed to facilitate the large numbers of breakdown on a polymer film required to characterize statistical breakdown properties at the low probabilities relevant to capacitor design. Using this system, a large number of breakdown data can be acquired easily resulting in a better understanding of the polymer film dielectric strength, especially at low breakdown probability. Shielded power cables are employed widely in electric power systems. A good understanding of high frequency dielectric properties of shielded power cable is important for diagnostic testing of such cables using partial discharge measurement and other techniques which depend on propagation of nanosecond pulses along the cable. Experiments and theoretical computations have been conducted to extend and improve understanding of high frequency propagation characteristics of shielded power cable.

  8. Voltage clamp simulation.

    PubMed

    Kootsey, J M

    1975-04-01

    The voltage clamp experiment on the squid giant axon is successful because of the special characteristics of the preparation: cylindrical shape, large diameter, and so on. The method is much more difficult to apply to small cells and to networks of cells because voltage gradients and unwanted stray impedances are not readily eliminated. Simulation of the voltage clamp experiment is proposed as a method for determining when these factors and the characteristics of the clamp electronics affect the experimental results, for evaluating experimental techniques for improving the quality of the clamp, and as a possible method of learning something about the membrane when no experimental improvement is feasible. The numerical methods for including one spatial variable in the analysis are reviewed briefly. Several examples of voltage clamp simulations are discussed: double sucrose gap clamp of axons, clamp of the giant synapse, single sucrose gap clamp of cardiac muscle bundles, point clamp of the end of a fiber bundle, and the steady-state three-microelectrode clamp of a cable with nonlinear membrane. The results indicate that the quality of a clamp cannot be evaluated from the voltage and current records as commonly measured. PMID:1123090

  9. An experimental investigation on the airside performance of fin-and-tube heat exchangers having sinusoidal wave fins

    NASA Astrophysics Data System (ADS)

    Youn, B.; Kim, N. H.

    2007-10-01

    The heat transfer and friction characteristics of the heat exchangers having sinusoidal wave fins were experimentally investigated. Twenty-nine samples having different waffle heights (1.5 and 2.0 mm), fin pitches (1.3 1.7 mm) and tube rows (1 3) were tested. Focus was given to the effect of waffle configuration (herringbone or sinusoidal) on the heat transfer and friction characteristics. Results show that the sinusoidal wave geometry provides higher heat transfer coefficients and friction factors than the herringbone wave geometry, and the difference increases as the number of row increases. The j/ f ratios of the herringbone wave geometry, however, are larger than those of the sinusoidal wave geometry. Compared with the herringbone wave geometry, the sinusoidal wave geometry yielded a weak row effect, which suggests a superior heat transfer performance at the fully developed flow region for the sinusoidal wave geometry. Possible reasoning is provided considering the flow characteristics in wavy channels. Within the present geometric variations, the effect of waffle height on the heat transfer coefficient was not prominent. The effect of fin pitch was also negligible. Existing correlations highly overpredicted both the heat transfer coefficients and friction factors. A new correlation was developed based on the present data.

  10. Electron launching voltage monitor

    DOEpatents

    Mendel, Clifford W.; Savage, Mark E.

    1992-01-01

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

  11. Electron launching voltage monitor

    DOEpatents

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

    1992-03-17

    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.

  12. High voltage coaxial switch

    DOEpatents

    Rink, J.P.

    1983-07-19

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

  13. High voltage coaxial switch

    DOEpatents

    Rink, John P.

    1983-07-19

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

  14. Voltage controlled current source

    DOEpatents

    Casne, Gregory M.

    1992-01-01

    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.

  15. High-voltage engineering

    SciTech Connect

    Khalifa, M. )

    1990-01-01

    The topics covered in this book include gas discharge, insulating materials, system earthing, overvoltage and insulation coordination, and high-voltage equipment and testing techniques. In two chapters, the principles of design of high-voltage busbars are discussed, together with their insulation and ampacity, whether they are of conventional air-insulated type or the metal-clad GIS types now widely used at the HV and EHV levels. The various types of circuit breakers and cables are discussed including mention of solid-state breakers and superconducting cables. The authors present a treatment of power system grounding, external and internal overvoltages imposed on system insulation, and techniques adopted for insulation coordination. The last three chapters focus on the area of insulation testing, covering the topics of high-voltage generation, measurements, and standard specifications.

  16. High-frequency ac power distribution in Space Station

    NASA Technical Reports Server (NTRS)

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

    1990-01-01

    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.

  17. High-Voltage Digital-To-Analog Converter

    NASA Technical Reports Server (NTRS)

    Huston, Steven W.

    1990-01-01

    High-voltage 10-bit digital-to-analog converter operates under computer control to put out voltages up to 500 V at currents up to 35 mA. Circuit includes high-voltage power supply used to generate high-voltage square wave at frequency set by computer at value between 0.2 Hz and 10 Hz. Used to drive 0.02-microfarad, 1-kV capacitor at slewing rate of 1 V/microsecond to provide signal for robotic imaging system.

  18. Unique cell type-specific junctional complexes in vascular endothelium of human and rat liver sinusoids.

    PubMed

    Géraud, Cyrill; Evdokimov, Konstantin; Straub, Beate K; Peitsch, Wiebke K; Demory, Alexandra; Dörflinger, Yvette; Schledzewski, Kai; Schmieder, Astrid; Schemmer, Peter; Augustin, Hellmut G; Schirmacher, Peter; Goerdt, Sergij

    2012-01-01

    Liver sinusoidal endothelium is strategically positioned to control access of fluids, macromolecules and cells to the liver parenchyma and to serve clearance functions upstream of the hepatocytes. While clearance of macromolecular debris from the peripheral blood is performed by liver sinusoidal endothelial cells (LSECs) using a delicate endocytic receptor system featuring stabilin-1 and -2, the mannose receptor and CD32b, vascular permeability and cell trafficking are controlled by transcellular pores, i.e. the fenestrae, and by intercellular junctional complexes. In contrast to blood vascular and lymphatic endothelial cells in other organs, the junctional complexes of LSECs have not yet been consistently characterized in molecular terms. In a comprehensive analysis, we here show that LSECs express the typical proteins found in endothelial adherens junctions (AJ), i.e. VE-cadherin as well as α-, β-, p120-catenin and plakoglobin. Tight junction (TJ) transmembrane proteins typical of endothelial cells, i.e. claudin-5 and occludin, were not expressed by rat LSECs while heterogenous immunreactivity for claudin-5 was detected in human LSECs. In contrast, junctional molecules preferentially associating with TJ such as JAM-A, B and C and zonula occludens proteins ZO-1 and ZO-2 were readily detected in LSECs. Remarkably, among the JAMs JAM-C was considerably over-expressed in LSECs as compared to lung microvascular endothelial cells. In conclusion, we show here that LSECs form a special kind of mixed-type intercellular junctions characterized by co-occurrence of endothelial AJ proteins, and of ZO-1 and -2, and JAMs. The distinct molecular architecture of the intercellular junctional complexes of LSECs corroborates previous ultrastructural findings and provides the molecular basis for further analyses of the endothelial barrier function of liver sinusoids under pathologic conditions ranging from hepatic inflammation to formation of liver metastasis. PMID:22509281

  19. 3D Hepatic Cultures Simultaneously Maintain Primary Hepatocyte and Liver Sinusoidal Endothelial Cell Phenotypes

    PubMed Central

    Kim, Yeonhee; Rajagopalan, Padmavathy

    2010-01-01

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

  20. Impact Testing and Simulation of a Sinusoid Foam Sandwich Energy Absorber

    NASA Technical Reports Server (NTRS)

    Jackson, Karen E.; Fasanella, Edwin L; Littell, Justin D.

    2015-01-01

    A sinusoidal-shaped foam sandwich energy absorber was developed and evaluated at NASA Langley Research Center through multi-level testing and simulation performed under the Transport Rotorcraft Airframe Crash Testbed (TRACT) research project. The energy absorber, designated the "sinusoid," consisted of hybrid carbon- Kevlar® plain weave fabric face sheets, two layers for each face sheet oriented at +/-45deg with respect to the vertical or crush direction, and a closed-cell ELFOAM(TradeMark) P200 polyisocyanurate (2.0-lb/ft3) foam core. The design goal for the energy absorber was to achieve an average floor-level acceleration of between 25- and 40-g during the full-scale crash test of a retrofitted CH-46E helicopter airframe, designated TRACT 2. Variations in the design were assessed through quasi-static and dynamic crush testing of component specimens. Once the design was finalized, a 5-ft-long subfloor beam was fabricated and retrofitted into a barrel section of a CH-46E helicopter. A vertical drop test of the barrel section was conducted onto concrete to evaluate the performance of the energy absorber prior to retrofit into TRACT 2. Finite element models were developed of all test articles and simulations were performed using LSDYNA ®, a commercial nonlinear explicit transient dynamic finite element code. Test analysis results are presented for the sinusoid foam sandwich energy absorber as comparisons of load-displacement and acceleration-time-history responses, as well as predicted and experimental structural deformations and progressive damage for each evaluation level (component testing through barrel section drop testing).

  1. Geomagnetism and induced voltage

    NASA Astrophysics Data System (ADS)

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

    2010-07-01

    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 initiated by the change in the magnetic flux due to the Earth's magnetic field and movement. This simple and enjoyable experiment will demonstrate how basic concepts in physics and geology can help us think about possible health effects due to the induced voltage.

  2. High voltage variable diameter insulator

    DOEpatents

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

    1982-07-13

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

  3. Low-voltage thin-film electroluminescent devices with low-resistivity stacked insulators

    NASA Astrophysics Data System (ADS)

    Zhang, Jia-Yu; Gu, Pei-Fu; Liu, Xu; Tang, Jin-Fa

    1997-01-01

    The characteristics and mechanism of low-voltage-driven thin-film electroluminescent (TFEL) devices with low-resistivity (10 6 10 7 - cm) SiO 2 Ta 2 O 5 and Al 2 O 3 Ta 2 O 5 stacked insulating films have been studied. At 50-Hz sinusoidal wave voltage excitation, the threshold voltage of devices with a ZnS:Mn emitting layer is below 40 V, and the brightness and luminous efficiency are above 1000 cd m 2 and 4 lm W, respectively, with 60 V voltage. The characteristics of brightness versus voltage ( B V ) curves, integrated charge versus voltage ( Q V ) figures, and luminous efficiency versus voltage ( V ) characteristics are different from conventional devices. The study of a special semiconductor layer a thin probe-doped layer located at a different part of the pure ZnS layer-has proved that the excitation efficiency is not homogeneous across the emitting layer in this kind of device, and its value decreases from the anode toward the cathode, which is opposite of that made with TFEL devices with high-resistivity insulators. By offering a model of space-charge-limited current, the mechanism of low-voltage-driven thin-film electroluminescence, its optoelectronic characteristics, and the distribution characteristics of excitation efficiency across the emitting layer can be thoroughly explained.

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

    SciTech Connect

    Sohbatzadeh, Farshad; Omran, Azadeh Valinataj

    2014-11-15

    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.

  5. Electromagnetic characterization of current transformer with toroidal core under sinusoidal conditions

    NASA Astrophysics Data System (ADS)

    Koprivica, Branko; Milovanovic, Alenka

    2016-04-01

    The aim of this paper is to present a new procedure for the electromagnetic analysis of a measuring current transformer under sinusoidal conditions in its electrical and magnetic circuit. The influence of the magnetic hysteresis has been taken into account using the measured inverse magnetization curve and phase lag between the time waveforms of the magnetic field and the magnetic induction. Using the proposed analysis, ratio and phase errors of the current transformer have been calculated. The results of the calculation have been compared with experimental results and a good agreement has been found.

  6. Investigation of phase error correction for digital sinusoidal phase-shifting fringe projection profilometry

    NASA Astrophysics Data System (ADS)

    Ma, S.; Quan, C.; Zhu, R.; Tay, C. J.

    2012-08-01

    Digital sinusoidal phase-shifting fringe projection profilometry (DSPFPP) is a powerful tool to reconstruct three-dimensional (3D) surface of diffuse objects. However, a highly accurate profile is often hindered by nonlinear response, color crosstalk and imbalance of a pair of digital projector and CCD/CMOS camera. In this paper, several phase error correction methods, such as Look-Up-Table (LUT) compensation, intensity correction, gamma correction, LUT-based hybrid method and blind phase error suppression for gray and color-encoded DSPFPP are described. Experimental results are also demonstrated to evaluate the effectiveness of each method.

  7. Simulation of residual oil displacement in a sinusoidal channel with the lattice Boltzmann method

    NASA Astrophysics Data System (ADS)

    Otomo, Hiroshi; Fan, Hongli; Hazlett, Randy; Li, Yong; Staroselsky, Ilya; Zhang, Raoyang; Chen, Hudong

    2015-10-01

    We simulate oil slug displacement in a sinusoidal channel in order to validate computational models and algorithms for multi-component flow. This case fits in the gap between fully realistic cases characterized by complicated geometry and academic cases with simplistic geometry. Our computational model is based on the lattice Boltzmann method and allows for variation of physical parameters such as wettability and viscosity. The effect of variation of model parameters is analyzed, in particular via comparison with analytical solutions. We discuss the requirements for accurate solution of the oil slug displacement problem.

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

    NASA Astrophysics Data System (ADS)

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

    2012-08-01

    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.

  9. Self-mixing interferometry based on sinusoidal phase modulation and integrating-bucket method

    NASA Astrophysics Data System (ADS)

    Guo, Dongmei; Wang, Ming

    2010-05-01

    In order to realize real-time displacement measurement with high resolution, sinusoidal phase modulation and integrating-bucket method are introduced in the self-mixing interference (SMI) system firstly. The phase of the laser beam is modulated by an electro-optic modulator (EOM) in the external cavity. Theoretical analysis, simulation results and error evaluation are presented. Experimentally, the micro-displacement of a high-precision commercial PZT is reconstructed and the reconstruction accuracy is on the order of nanometers for displacements of a few micrometers.

  10. An automatic AC/DC thermal voltage converter and AC voltage calibration system

    NASA Astrophysics Data System (ADS)

    Lentner, K. J.; Flach, D. R.; Bell, B. A.

    1985-10-01

    An automatic ac/dc difference calibration system is described which uses direct measurement of thermoelement emfs. In addition to ac/dc difference testing, the system can be used to measure some important characteristics of thermoelements, as well as to calibrate ac voltage calibrators and precision voltmeters. The system operates over a frquency range from 20 Hz to 100 kHz, covering the voltage range from 0.5 V to 1 kv. For all voltages the total measurement uncertainties expected (including the uncertainty of the specific reference thermal converters used) were 50 parts per million (ppm) at frequencies from 20 Hz to 20 kHz, inclusive, and 100 ppm at higher frequencies up to 100 kHz.

  11. Geomagnetism and Induced Voltage

    ERIC Educational Resources Information Center

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

    2010-01-01

    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

  12. Measuring Breakdown Voltage.

    ERIC Educational Resources Information Center

    Auer, Herbert J.

    1978-01-01

    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)

  13. Voltage-Controlled Oscillator

    NASA Technical Reports Server (NTRS)

    1995-01-01

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

  14. Geomagnetism and Induced Voltage

    ERIC Educational Resources Information Center

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

    2010-01-01

    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…

  15. Design and applications of a flicker voltage generator

    SciTech Connect

    Chang, W.N.; Wu, C.J.

    1995-12-31

    In this paper, a 200W flicker voltage generator is made by using microcomputers and linear amplification circuits. The modulation amplitudes and frequencies based on the UIE {Delta}V{sub 10} evaluation can be arbitrarily assigned by software with high accuracy. The flicker voltage signals measured at the customer side also can be re-generated. Some applications, such as evaluating the effects of flicker voltage on incandescent and compact fluorescent lamps (CFLs), are also made. From experimental tests by use of the flicker voltage generator, the properties of some compact fluorescent lamps and incandescent lamps are compared. Those properties describe the relation between input voltage variation and output flux of lamps, such that there is direct description of influences of flicker voltages on lamps.

  16. Age-Related Changes in Scavenger ReceptorMediated Endocytosis in Rat Liver Sinusoidal Endothelial Cells

    PubMed Central

    Simon-Santamaria, Jaione; Malovic, Ivana; Warren, Alessandra; Oteiza, Ana; Le Couteur, David; Smedsrd, Brd; McCourt, Peter

    2010-01-01

    Liver sinusoidal endothelial cells (LSECs) play an essential role in systemic waste clearance by effective endocytosis of blood-borne waste macromolecules. We aimed to study LSECs scavenger function during aging, and whether age-related morphological changes (eg, defenestration) affect this function, in F344/BN F1 rats. Endocytosis of the scavenger receptor ligand formaldehyde-treated serum albumin was significantly reduced in LSECs from old rats. Ligand degradation, LSEC protein expression of the major scavenger receptors for formaldehyde-treated serum albumin endocytosis, stabilin-1 and stabilin-2, and their staining patterns along liver sinusoids, was similar at young and old age, suggesting that other parts of the endocytic machinery are affected by aging. Formaldehyde-treated serum albumin uptake per cell, and cell porosity evaluated by electron microscopy, was not correlated, indicating that LSEC defenestration is not linked to impaired endocytosis. We report a significantly reduced LSEC endocytic capacity at old age, which may be especially important in situations with increased circulatory waste loads. PMID:20576648

  17. Long-term maintenance of a microfluidic 3D human liver sinusoid.

    PubMed

    Prodanov, Ljupcho; Jindal, Rohit; Bale, Shyam Sundhar; Hegde, Manjunath; McCarty, William J; Golberg, Inna; Bhushan, Abhinav; Yarmush, Martin L; Usta, Osman Berk

    2016-01-01

    The development of long-term human organotypic liver-on-a-chip models for successful prediction of toxic response is one of the most important and urgent goals of the NIH/DARPA's initiative to replicate and replace chronic and acute drug testing in animals. For this purpose, we developed a microfluidic chip that consists of two microfluidic chambers separated by a porous membrane. The aim of this communication is to demonstrate the recapitulation of a liver sinusoid-on-a-chip, using human cells only for a period of 28 days. Using a step-by-step method for building a 3D microtissue on-a-chip, we demonstrate that an organotypic in vitro model that reassembles the liver sinusoid microarchitecture can be maintained successfully for a period of 28 days. In addition, higher albumin synthesis (synthetic) and urea excretion (detoxification) were observed under flow compared to static cultures. This human liver-on-a-chip should be further evaluated in drug-related studies. PMID:26152452

  18. A Novel Modular Bioreactor to In Vitro Study the Hepatic Sinusoid

    PubMed Central

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

    2014-01-01

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

  19. Non-sinusoidal current-phase relations in SFS pi-Josephson junctions

    NASA Astrophysics Data System (ADS)

    van Harlingen, Dale J.

    2010-03-01

    We report the direct observation of a sin(2φ) component in the current-phase relation (CPR) of Superconductor-Ferromagnet-Superconductor (SFS) Josephson junctions. The deviation from a sinusoidal CPR is most evident near the crossover between the 0-junction to π-junction states reached by tuning the thickness of the ferromagnet barrier and the temperature. We measure the CPR in Nb-CuNi-Nb junctions using a phase-sensitive Josephson interferometer technique in which the junctions are incorporated into a superconducting loop coupled to a dc SQUID. We correlate the CPR data with measurements of subharmonic Shapiro steps and anomalous critical current diffraction patterns that have previously been cited as evidence for higher-order Josephson tunneling components. We will discuss possible origins and implications for the non-sinusoidal component. In collaboration with M.J.A. Stoutimore (University of Illinois at Urbana-Champaign) and A.Yu. Rusanov, V.A. Oboznov, V.V. Bolginov, A.N. Rossolenko, and V.V. Ryazanov (Institute of Solid State Physics, Russian Academy of Sciences, Chernogolovka, Russia).

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

    SciTech Connect

    Geoffroy, J.S.

    1987-01-01

    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.

  1. The Design of In Vitro Liver Sinusoid Mimics Using Chitosan–Hyaluronic Acid Polyelectrolyte Multilayers

    PubMed Central

    Kim, Yeonhee; Larkin, Adam L.; Davis, Richey M.

    2010-01-01

    Interactions between hepatocytes and liver sinusoidal endothelial cells (LSECs) are essential for the development and maintenance of hepatic phenotypic functions. We report the assembly of three-dimensional liver sinusoidal mimics comprised of primary rat hepatocytes, LSECs, and an intermediate chitosan–hyaluronic acid polyelectrolyte multilayer (PEM). The height of the PEMs ranged from 30 to 55 nm and exhibited a shear modulus of ∼100 kPa. Hepatocyte–PEM cellular constructs exhibited stable urea and albumin production over a 7-day period, and these values were either higher or similar to cells cultured in a collagen sandwich. This is of significance because the thickness of a collagen gel is ∼1000-fold higher than the height of the chitosan–hyaluronic acid PEM. In the hepatocyte–PEM–LSEC liver-mimetic cellular constructs, LSEC phenotype was maintained, and these cultures exhibited stable urea and albumin production. CYP1A1/2 activity measured over a 7-day period was significantly higher in the hepatocyte–PEM–LSEC constructs than in collagen sandwich cultures. A 16-fold increase in CYP1A1/2 activity was observed for hepatocyte–PEM–10,000 LSEC samples, thereby suggesting that interactions between hepatocytes and LSECs are critical in enhancing the detoxification capability in hepatic cultures in vitro. PMID:20491586

  2. Controlled generation of nonlinear resonances through sinusoidal lattice modes in Bose-Einstein condensate

    NASA Astrophysics Data System (ADS)

    Das, Priyam; Panigrahi, Prasanta K.

    2015-12-01

    We study Bose-Einstein condensate in the combined presence of time modulated optical lattice and harmonic trap in the mean-field approach. Through the self-similar method, we show the existence of sinusoidal lattice modes in this inhomogeneous system, commensurate with the lattice potential. A significant advantage of this system is wide tunability of the parameters through chirp management. The combined effect of the interaction, harmonic trap and lattice potential leads to the generation of nonlinear resonances, exactly where the matter wave changes its direction. When the harmonic trap is switched off, the BEC undergoes a nonlinear compression for the static optical lattice potential. For better understanding of chirp management and the nature of the sinusoidal excitation, we investigate the energy spectrum of the condensate, which clearly reveals the generation of nonlinear resonances in the appropriate regime. We have also identified a classical dynamical phase transition occurring in the system, where loss of superfluidity takes the superfluid phase to an insulating state.

  3. Chronic Passive Venous Congestion drives Hepatic Fibrogenesis via Sinusoidal Thrombosis and Mechanical Forces

    PubMed Central

    Simonetto, Douglas A; Yang, Hui-yin; Yin, Meng; de Assuncao, Thiago M; Kwon, Jung Hee; Hilsher, Moira; Pan, Shuchong; Yang, Liu; Bi, Yan; Beyder, Arthur; Cao, Sheng; Simari, Robert D; Ehman, Richard; Kamath, Patrick S; Shah, Vijay H

    2014-01-01

    Chronic passive hepatic congestion (congestive hepatopathy) leads to hepatic fibrosis; however the mechanisms involved in this process are not well understood. We developed a murine experimental model of congestive hepatopathy through partial ligation of the inferior vena cava (pIVCL). C57BL/6 and transgenic mice overexpressing tissue factor pathway inhibitor (SM22α -TFPI) were subjected to pIVCL or SHAM. Liver and blood samples were collected and analyzed in immunohistochemical, morphometric, real-time polymerase chain reaction and western blot assays. Hepatic fibrosis and portal pressure were significantly increased after pIVCL concurrent with hepatic stellate cell (HSC) activation. Liver stiffness, as assessed by magnetic resonance elastography, correlated with portal pressure and preceded fibrosis in our model. Hepatic sinusoidal thrombosis as evidenced by fibrin deposition was demonstrated both in mice after pIVCL as well as in humans with congestive hepatopathy. Warfarin treatment and TFPI overexpression both had a protective effect on fibrosis development and HSC activation after pIVCL. In vitro studies show that congestion stimulates HSC fibronectin (FN) fibril assembly through direct effects of thrombi as well as by virtue of mechanical strain. Pretreatment with either Mab13 or Cytochalasin-D, to inhibit β-integrin or actin polymerization, respectively, significantly reduced fibrin and stretch induced FN fibril assembly. Conclusion Chronic hepatic congestion leads to sinusoidal thrombosis and strain, which in turn promote hepatic fibrosis. These studies mechanistically link congestive hepatopathy to hepatic fibrosis. PMID:25142214

  4. Three dimensional analyses of scattering by pressure-release sinusoidal surfaces.

    PubMed

    Welton, P J

    2012-01-01

    Scattering by pressure-release sinusoidal surfaces in three dimensions is analyzed using the Fresnel phase approximation and realistic source and receiver directivity approximations. Geometrical shadowing and second-order scattering are explicitly included to explore the validity of the Kirchhoff approximation. No restrictions on the surface heights and slopes are made. The "goodness" of the resulting expressions is verified by requiring the pressure scattered by a sinusoidal surface to reduce to the image solution as the surface amplitude goes to zero. The first-order scattered pressure achieves a very good approximation to the image solution, and the second-order scattered pressure goes to zero, as expected, under this requirement. The theory is compared with available experimental scattering measurements, and the agreement is good. Because the slopes on the experimental surface are very steep, shadowing corrections are indispensible to achieving accurate first and second order scattering results. Shadowing has a greater impact on the scattering prediction than the second-order scattering contribution. This suggests that the Kirchhoff approximation may be more robust when incorporated into a theory including a detailed shadowing treatment as well as the Fresnel phase approximation and a good directivity approximation. PMID:22280571

  5. On shock driven jetting of liquid from non-sinusoidal surfaces into a vacuum

    NASA Astrophysics Data System (ADS)

    Cherne, F. J.; Hammerberg, J. E.; Andrews, M. J.; Karkhanis, V.; Ramaprabhu, P.

    2015-11-01

    Previous work employed Richtmyer-Meshkov theory to describe the development of spikes and bubbles from shocked sinusoidal surfaces. Here, we discuss the effects of machining different two-dimensional shaped grooves in copper and examine the resulting flow of the material after being shocked into liquid on release. For these simulations, a high performance molecular dynamics code, SPaSM, was used with machined grooves of kh0 = 1 and kh0 = 1/8, where 2h0 is the peak-to-valley height of the perturbation with wavelength λ, and k = 2π/λ. The surface morphologies studied include a Chevron, a Fly-Cut, a Square-Wave, and a Gaussian. We describe extensions to an existing ejecta source model that better captures the mass ejected from these surfaces. We also investigate the same profiles at length scales of order 1 cm for an idealized fluid equation of state using the FLASH continuum hydrodynamics code. Our findings indicate that the resulting mass can be scaled by the missing area of a sinusoidal curve with an effective wavelength, λeff, that has the same missing area. Our extended ejecta mass formula works well for all the shapes considered and captures the corresponding time evolution and total mass.

  6. Vibration control and sinusoidal external force estimation of a flexible shaft using piezoelectric actuators

    NASA Astrophysics Data System (ADS)

    Suzuki, Y.; Kagawa, Y.

    2012-12-01

    In the balancing of a flexible rotor, insufficient damping for a rotor-bearing system may cause excessive vibrations in trial runs. In addition, conventional modal balancing methods are generally time-consuming because they try to balance the rotor one mode at a time. To overcome these issues, we developed a control system using multilayer piezoelectric actuators in order to suppress the vibration of a flexible rotor and to estimate its modal unbalances simultaneously. The H-infinity controller was designed to achieve robust performance for an uncertainty of the system, and its damping ability was examined in free and forced vibration tests. Large reductions were observed in the response near resonance. Then, steady-state responses of the system excited by sinusoidal forces were measured to investigate the estimation accuracy of sinusoidal external forces, and good agreement was observed between the estimated and the experimental results. Furthermore, it was demonstrated that feedforward plus feedback control using the estimated modal force significantly improved the performance of suppression of flexible shaft vibrations compared with simple feedback control.

  7. Liver Sinusoidal Endothelial Cells Escape Senescence by Loss of p19ARF

    PubMed Central

    Koudelkova, Petra; Weber, Gerhard; Mikulits, Wolfgang

    2015-01-01

    Liver sinusoidal endothelial cells (LSECs) represent a highly differentiated cell type that lines hepatic sinusoids. LSECs form a discontinuous endothelium due to fenestrations under physiological conditions, which are reduced upon chronic liver injury. Cultivation of rodent LSECs associates with a rapid onset of stress-induced senescence a few days post isolation, which limits genetic and biochemical studies ex vivo. Here we show the establishment of LSECs isolated from p19ARF-/- mice which undergo more than 50 cell doublings in the absence of senescence. Isolated p19ARF-/- LSECs display a cobblestone-like morphology and show the ability of tube formation. Analysis of DNA content revealed a stable diploid phenotype after long-term passaging without a gain of aneuploidy. Notably, p19ARF-/- LSECs express the endothelial markers CD31, vascular endothelial growth factor receptor (VEGFR)-2, VE-cadherin, von Willebrand factor, stabilin-2 and CD146 suggesting that these cells harbor and maintain an endothelial phenotype. In line, treatment with small molecule inhibitors against VEGFR-2 caused cell death, demonstrating the sustained ability of p19ARF-/- LSECs to respond to anti-angiogenic therapeutics. From these data we conclude that loss of p19ARF overcomes senescence of LSECs, allowing immortalization of cells without losing endothelial characteristics. Thus, p19ARF-/- LSECs provide a novel cellular model to study endothelial cell biology. PMID:26528722

  8. Biliary obstruction dissipates bioelectric sinusoidal-canalicular barrier without altering taurocholate uptake

    SciTech Connect

    Cotting, J.; Zysset, T.; Reichen, J.

    1989-02-01

    To study immediate events during extrahepatic cholestasis, we investigated the effect of short-term biliary obstruction on the bioelectrical sinusoidal-canalicular barrier in the rat using molecular weight-matched uncharged and negatively charged inert solute pairs. The bioelectrical barrier averaged -22 +/- 5 and -18 +/- 4 mV (NS) using the pair carboxy-/methoxyinulin and ferrocyanide/sucrose, respectively. After a 20-min biliary obstruction both decreased by 61 and 11%, respectively, but only the large molecular weight pair (the inulins) returned to base line after release of the obstruction. Inert solute clearances were increased after short biliary obstruction depending on molecular size and negative charge (ferrocyanide greater than sucrose greater than carboxyinulin greater than inulin), suggesting that both permeability and bioelectrical barriers were affected by obstruction. The hepatic extraction in vivo of a passively transported drug not excreted into bile (D-propranolol) was not affected by obstruction, whereas that of an actively transported drug (glycocholate) decreased from 66 +/- 8 to 41 +/- 20% during biliary obstruction (P less than 0.01). Unidirectional transfer of glycocholate was not affected by short-term biliary obstruction in the situ perfused rat liver; however, 2 min after (14C)glycocholate administration, increased return was observed in hepatic venous effluent in obstructed animals. Our findings demonstrate a loss of the bioelectrical barrier immediately after short-term biliary obstruction. Decreased hepatic extraction in the view of unaltered sinusoidal uptake demonstrates regurgitation of bile into blood during short-term biliary obstruction.

  9. On shock driven jetting of liquid from non-sinusoidal surfaces into a vacuum

    SciTech Connect

    Cherne, F. J.; Hammerberg, J. E.; Andrews, M. J.; Karkhanis, V.; Ramaprabhu, P.

    2015-11-09

    Other work employed Richtmyer-Meshkov theory to describe the development of spikes and bubblesfrom shocked sinusoidal surfaces. Here, we discuss the effects of machining different two-dimensional shaped grooves in copper and examine the resulting flow of the material after being shocked into liquid on release. For these simulations, a high performance molecular dynamics code, SPaSM, was used with machined grooves of kh 0 = 1 and kh 0 = 1/8, where 2h 0 is the peak-to-valley height of the perturbation with wavelength λ, and k = 2π/λ. The surface morphologies studied include a Chevron, a Fly-Cut, a Square-Wave, and a Gaussian. Furthermore, we describe extensions to an existing ejecta source model that better captures the mass ejected from these surfaces. We also investigate the same profiles at length scales of order 1 cm for an idealized fluid equation of state using the FLASH continuum hydrodynamics code. Our findings indicate that the resulting mass can be scaled by the missing area of a sinusoidal curve with an effective wavelength, λeff , that has the same missing area. Finally, our extended ejecta mass formula works well for all the shapes considered and captures the corresponding time evolution and total mass.

  10. On shock driven jetting of liquid from non-sinusoidal surfaces into a vacuum

    DOE PAGESBeta

    Cherne, F. J.; Hammerberg, J. E.; Andrews, M. J.; Karkhanis, V.; Ramaprabhu, P.

    2015-11-09

    Other work employed Richtmyer-Meshkov theory to describe the development of spikes and bubblesfrom shocked sinusoidal surfaces. Here, we discuss the effects of machining different two-dimensional shaped grooves in copper and examine the resulting flow of the material after being shocked into liquid on release. For these simulations, a high performance molecular dynamics code, SPaSM, was used with machined grooves of kh 0 = 1 and kh 0 = 1/8, where 2h 0 is the peak-to-valley height of the perturbation with wavelength λ, and k = 2π/λ. The surface morphologies studied include a Chevron, a Fly-Cut, a Square-Wave, and a Gaussian.more » Furthermore, we describe extensions to an existing ejecta source model that better captures the mass ejected from these surfaces. We also investigate the same profiles at length scales of order 1 cm for an idealized fluid equation of state using the FLASH continuum hydrodynamics code. Our findings indicate that the resulting mass can be scaled by the missing area of a sinusoidal curve with an effective wavelength, λeff , that has the same missing area. Finally, our extended ejecta mass formula works well for all the shapes considered and captures the corresponding time evolution and total mass.« less

  11. Measurement and mathematical modelling of elastic and resistive lung mechanical properties studied at sinusoidal expiratory flow.

    PubMed

    Bitzén, Ulrika; Niklason, Lisbet; Göransson, Ingegerd; Jonson, Björn

    2010-11-01

    Elastic pressure/volume (P(el) /V) and elastic pressure/resistance (P(el) /R) diagrams reflect parenchymal and bronchial properties, respectively. The objective was to develop a method for determination and mathematical characterization of P(el) /V and P(el) /R relationships, simultaneously studied at sinusoidal flow-modulated vital capacity expirations in a body plethysmograph. Analysis was carried out by iterative parameter estimation based on a composite mathematical model describing a three-segment P(el) /V curve and a hyperbolic P(el) /R curve. The hypothesis was tested that the sigmoid P(el) /V curve is non-symmetric. Thirty healthy subjects were studied. The hypothesis of a non-symmetric P(el) /V curve was verified. Its upper volume asymptote was nearly equal to total lung capacity (TLC), indicating lung stiffness increasing at high lung volume as the main factor limiting TLC at health. The asymptotic minimal resistance of the hyperbolic P(el) /R relationship reflected lung size. A detailed description of both P(el) /V and P(el) /R relationships was simultaneously derived from sinusoidal flow-modulated vital capacity expirations. The nature of the P(el) /V curve merits the use of a non-symmetric P(el) /V model. PMID:20726995

  12. Tailored Voltage Waveform Capacitively-Coupled Plasmas

    NASA Astrophysics Data System (ADS)

    Booth, Jean-Paul; Lafleur, Trevor; Delattre, Pierre-Alexandre; Johnson, Erik

    2012-10-01

    A major limitation of large-area capacitively-coupled plasmas for materials processing is the inability to increase plasma density without increasing ion bombardment energy. Heil et al. (J. Phys. D 41. 165202, (2008)) demonstrated that for a driving voltage comprising one frequency, f, and it's harmonic 2f, the symmetry of the sheaths can be broken (the Electrical Asymmetry Effect, EAE). We have investigated large-area plasmas (50cm dia) in Ar driven by arbitrary voltage waveforms. Specifically we studied waveforms comprising sharp positive pulses (10-20ns wide, 15MHz repetition frequency). The voltage waveform was measured by an HV probe close to the powered electrode edge, the electron density was measured with a microwave hairpin resonator, the ion flux was measured by an array of planar ion flux probes in the grounded counter-electrode, and the power absorbed was determined from the current and voltage waveforms measured by a derivative probe. As well as the expected EAE observed in the electrode self-bias, we were able to demonstrate a dramatic increase in electron density (and concomitant increased power absorption) with reduced pulse-width at constant amplitude, in qualitative agreement with recent PIC simulations (Lafleur et al, APL 100, 194101(2012)).

  13. Development of Automatic Voltage Regulator for Low Voltage Distribution Systems

    NASA Astrophysics Data System (ADS)

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

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

  14. Adaptive filtering for clutter suppression in high frequency radar

    NASA Astrophysics Data System (ADS)

    Khan, Rafaat H.

    High frequency (HF) radar has the unique potential for over the horizon detection of ocean surface targets. However, ocean waves are also strong reflectors for HF radar and this high clutter level has limited its application for target detection. New results from the time domain analysis of ocean clutter show that it can be modelled as two angle modulated signals. This may be used to selectively suppress the clutter component and enhance the target detection performance. The practical implementation of clutter suppression, based upon this model, involves tracking of multiple time-varying sinusoids. An adaptive filtering technique to track time-varying sinusoids is discussed and initial results are presented.

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    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 μm 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 μs/V for up-tracking and 6 μs/V for down-tracking. Besides, the recovery time is less than 8 μs while the load current suddenly changes 400 mA.

  16. The Continuity of Right and Left Ventricular Myocardial Sinusoidal Spaces and its Relation to Right Ventricular Implants

    PubMed Central

    Vineberg, Arthur; Syed, A. Kadir

    1970-01-01

    Evidence is presented which indicates that blood leaving side branches of an internal mammary artery implanted into the anterior wall of the right ventricle flows from the tunnel in which it lies through myocardial sinusoidal spaces of the anterior right ventricular wall across the midline to fill corresponding spaces in the anterior wall of the left ventricle and thence is carried to the left coronary sinus. The myocardial sinusoidal spaces of right and left ventricles have been well outlined, using injections of polyvinyl acetate and the technique of digestion casts. We have been able to show that there is no barrier between the myocardial sinusoids of the right circulation and those related to the anterior descending branch of the left coronary artery. In structure, these myocardial sinusoidal spaces are quite different from the intramyocardial coronary arteriolar zones which, in 93% of human hearts, are separated from one another without collateral communication. The continuity of the right and left ventricular myocardial sinusoids explains why implantation of a right internal mammary artery into the anterior wall of the right ventricle combined with a corresponding left implant, epicardiectomy and free omental graft, has been so effective in our hands in the treatment of far-advanced human coronary artery insufficiency. ImagesFIG. 2FIG. 3FIG. 4FIG. 6FIG. 7FIG. 8FIG. 9 PMID:5445044

  17. A low voltage ``railgun''

    NASA Astrophysics Data System (ADS)

    Starr, Stanley O.; Youngquist, Robert C.; Cox, Robert B.

    2013-01-01

    Due to recent advances in solid-state switches and ultra-capacitors, it is now possible to construct a "railgun" that can operate at voltages below 20 V. Railguns typically operate above a thousand volts, generating huge currents for a few milliseconds to provide thousands of g's of acceleration to a small projectile. The low voltage railgun described herein operates for much longer time periods (tenths of seconds to seconds), has far smaller acceleration and speed, but can potentially propel a much larger object. The impetus for this development is to lay the groundwork for a possible ground-based supersonic launch track, but the resulting system may also have applications as a simple linear motor. The system would also be a useful teaching tool, requiring concepts from electrodynamics, mechanics, and electronics for its understanding, and is relatively straightforward to construct.

  18. Seizure entrainment with polarizing low-frequency electric fields in a chronic animal epilepsy model

    NASA Astrophysics Data System (ADS)

    Sunderam, Sridhar; Chernyy, Nick; Peixoto, Nathalia; Mason, Jonathan P.; Weinstein, Steven L.; Schiff, Steven J.; Gluckman, Bruce J.

    2009-08-01

    Neural activity can be modulated by applying a polarizing low-frequency (Lt100 Hz) electric field (PLEF). Unlike conventional pulsed stimulation, PLEF stimulation has a graded, modulatory effect on neuronal excitability, and permits the simultaneous recording of neuronal activity during stimulation suitable for continuous feedback control. We tested a prototype system that allows for simultaneous PLEF stimulation with minimal recording artifact in a chronic tetanus toxin animal model (rat) of hippocampal epilepsy with spontaneous seizures. Depth electrode local field potentials recorded during seizures revealed a characteristic pattern of field postsynaptic potentials (fPSPs). Sinusoidal voltage-controlled PLEF stimulation (0.5-25 Hz) was applied in open-loop cycles radially across the CA3 of ventral hippocampus. For stimulated seizures, fPSPs were transiently entrained with the PLEF waveform. Statistical significance of entrainment was assessed with Thomson's harmonic F-test, with 45/132 stimulated seizures in four animals individually demonstrating significant entrainment (p < 0.04). Significant entrainment for multiple presentations at the same frequency (p < 0.01) was observed in three of four animals in 42/64 stimulated seizures. This is the first demonstration in chronically implanted freely behaving animals of PLEF modulation of neural activity with simultaneous recording.

  19. Seizure entrainment with polarizing low frequency electric fields in a chronic animal epilepsy model

    PubMed Central

    Sunderam, Sridhar; Chernyy, Nick; Peixoto, Nathalia; Mason, Jonathan P.; Weinstein, Steven L.; Schiff, Steven J.; Gluckman, Bruce J.

    2009-01-01

    Neural activity can be modulated by applying a polarizing low frequency (≪ 100 Hz) electric field (PLEF). Unlike conventional pulsed stimulation, PLEF stimulation has a graded, modulatory effect on neuronal excitability, and permits the simultaneous recording of neuronal activity during stimulation suitable for continuous feedback control. We tested a prototype system that allows for simultaneous PLEF stimulation with minimal recording artifact in a chronic tetanus toxin animal model (rat) of hippocampal epilepsy with spontaneous seizures. Depth electrode local field potentials recorded during seizures revealed a characteristic pattern of field postsynaptic potentials (fPSPs). Sinusoidal voltage-controlled PLEF stimulation (0.5–25 Hz) was applied in open-loop cycles radially across the CA3 of ventral hippocampus. For stimulated seizures, fPSPs were transiently entrained with the PLEF waveform. Statistical significance of entrainment was assessed with Thomson’s harmonic F-test, with 45/132 stimulated seizures in 4 animals individually demonstrating significant entrainment (p < 0.04). Significant entrainment for multiple presentations at the same frequency (p < 0.01) was observed in 3 of 4 animals in 42/64 stimulated seizures. This is the first demonstration in chronically implanted freely behaving animals of PLEF modulation of neural activity with simultaneous recording. PMID:19602730

  20. Low voltage driven dielectric electro active polymer actuator with integrated piezoelectric transformer based driver

    NASA Astrophysics Data System (ADS)

    Andersen, T.; Rødgaard, M. S.; Thomsen, O. C.; Andersen, M. A. E.

    2011-04-01

    Today's Dielectric Electro Active Polymer (DEAP) actuators utilize high voltage (HV) in the range of kilo volts to fully stress the actuator. The requirement of HV is a drawback for the general use in the industry due to safety concerns and HV regulations. In order to avoid the HV interface to DEAP actuators, a low voltage solution is developed by integrating the driver electronic into a 110 mm tall cylindrical coreless Push InLastor actuator. To decrease the size of the driver, a piezoelectric transformer (PT) based solution is utilized. The PT is essentially an improved Rosen type PT with interleaved sections. Furthermore, the PT is optimized for an input voltage of 24 V with a gain high enough to achieve a DEAP voltage of 2.5 kV. The PT is simulated and verified through measurements on a working prototype. With the adapted hysteretic based control system; output voltage wave forms of both impulse response and sinusoidal shapes up to 2.5 kV are demonstrated. The control system, together with a carefully designed HV output stage, contributes to low power consumption at a static DEAP force. The HV stage consists of a HV measurement circuit and a triple diode voltage doubler optimized for low leakage current drawn from the DEAP. As a result, a 95 mm x 13 mm x 7 mm driver is integrated in a 110 mm x 32 mm actuator, forming a low voltage interfaced DEAP actuator.

  1. HIGH VOLTAGE GENERATOR

    DOEpatents

    Schwemin, A.J.

    1959-03-17

    A generator is presented for producing relatively large currents at high voltages. In general, the invention comprises a plurality of capacitors connected in series by a plurality of switches alternately disposed with the capacitors. The circuit is mounted for movement with respect to contact members and switch closure means so that a load device and power supply are connected across successive numbers of capacitors, while the other capacitors are successively charged with the same power supply.

  2. Increased voltage photovoltaic cell

    NASA Technical Reports Server (NTRS)

    Ross, B.; Bickler, D. B.; Gallagher, B. D. (Inventor)

    1985-01-01

    A photovoltaic cell, such as a solar cell, is provided which has a higher output voltage than prior cells. The improved cell includes a substrate of doped silicon, a first layer of silicon disposed on the substrate and having opposite doping, and a second layer of silicon carbide disposed on the first layer. The silicon carbide preferably has the same type of doping as the first layer.

  3. High Voltage Seismic Generator

    NASA Astrophysics Data System (ADS)

    Bogacz, Adrian; Pala, Damian; Knafel, Marcin

    2015-04-01

    This contribution describes the preliminary result of annual cooperation of three student research groups from AGH UST in Krakow, Poland. The aim of this cooperation was to develop and construct a high voltage seismic wave generator. Constructed device uses a high-energy electrical discharge to generate seismic wave in ground. This type of device can be applied in several different methods of seismic measurement, but because of its limited power it is mainly dedicated for engineering geophysics. The source operates on a basic physical principles. The energy is stored in capacitor bank, which is charged by two stage low to high voltage converter. Stored energy is then released in very short time through high voltage thyristor in spark gap. The whole appliance is powered from li-ion battery and controlled by ATmega microcontroller. It is possible to construct larger and more powerful device. In this contribution the structure of device with technical specifications is resented. As a part of the investigation the prototype was built and series of experiments conducted. System parameter was measured, on this basis specification of elements for the final device were chosen. First stage of the project was successful. It was possible to efficiently generate seismic waves with constructed device. Then the field test was conducted. Spark gap wasplaced in shallowborehole(0.5 m) filled with salt water. Geophones were placed on the ground in straight line. The comparison of signal registered with hammer source and sparker source was made. The results of the test measurements are presented and discussed. Analysis of the collected data shows that characteristic of generated seismic signal is very promising, thus confirms possibility of practical application of the new high voltage generator. The biggest advantage of presented device after signal characteristics is its size which is 0.5 x 0.25 x 0.2 m and weight approximately 7 kg. This features with small li-ion battery makes constructed device very mobile. The project is still developing.

  4. High voltage pulse conditioning

    DOEpatents

    Springfield, Ray M.; Wheat, Jr., Robert M.

    1990-01-01

    Apparatus for conditioning high voltage pulses from particle accelerators in order to shorten the rise times of the pulses. Flashover switches in the cathode stalk of the transmission line hold off conduction for a determinable period of time, reflecting the early portion of the pulses. Diodes upstream of the switches divert energy into the magnetic and electrostatic storage of the capacitance and inductance inherent to the transmission line until the switches close.

  5. Insulators for high voltages

    SciTech Connect

    Looms, J.S.T.

    1987-01-01

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

  6. APPARATUS FOR REGULATING HIGH VOLTAGE

    DOEpatents

    Morrison, K.G.

    1951-03-20

    This patent describes a high-voltage regulator of the r-f type wherein the modulation of the r-f voltage is accomplished at a high level, resulting in good stabilization over a large range of load conditions.

  7. Moderately nonlinear diffuse-charge dynamics under an ac voltage.

    PubMed

    Stout, Robert F; Khair, Aditya S

    2015-09-01

    The response of a symmetric binary electrolyte between two parallel, blocking electrodes to a moderate amplitude ac voltage is quantified. The diffuse charge dynamics are modeled via the Poisson-Nernst-Planck equations for a dilute solution of point-like ions. The solution to these equations is expressed as a Fourier series with a voltage perturbation expansion for arbitrary Debye layer thickness and ac frequency. Here, the perturbation expansion in voltage proceeds in powers of V_{o}/(k_{B}T/e), where V_{o} is the amplitude of the driving voltage and k_{B}T/e is the thermal voltage with k_{B} as Boltzmann's constant, T as the temperature, and e as the fundamental charge. We show that the response of the electrolyte remains essentially linear in voltage amplitude at frequencies greater than the RC frequency of Debye layer charging, D/λ_{D}L, where D is the ion diffusivity, λ_{D} is the Debye layer thickness, and L is half the cell width. In contrast, nonlinear response is predicted at frequencies below the RC frequency. We find that the ion densities exhibit symmetric deviations from the (uniform) equilibrium density at even orders of the voltage amplitude. This leads to the voltage dependence of the current in the external circuit arising from the odd orders of voltage. For instance, the first nonlinear contribution to the current is O(V_{o}^{3}) which contains the expected third harmonic but also a component oscillating at the applied frequency. We use this to compute a generalized impedance for moderate voltages, the first nonlinear contribution to which is quadratic in V_{o}. This contribution predicts a decrease in the imaginary part of the impedance at low frequency, which is due to the increase in Debye layer capacitance with increasing V_{o}. In contrast, the real part of the impedance increases at low frequency, due to adsorption of neutral salt from the bulk to the Debye layer. PMID:26465471

  8. Automatic voltage-imbalance detector

    SciTech Connect

    Bobbett, R.E.; McCormick, J.B.; Kerwin, W.J.

    1981-05-20

    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.

  9. High voltage variable diameter insulator

    DOEpatents

    Vanecek, David L.; Pike, Chester D.

    1984-01-01

    A high voltage feedthrough assembly (10) having a tubular insulator (15) extending between the ground plane ring (16) and the high voltage ring (30). The insulator (15) is made of Pyrex and decreases in diameter from the ground plane ring (16) to the high voltage ring (30), producing equipotential lines almost perpendicular to the wall (27) of the insulator (15) to optimize the voltage-holding capability of the feedthrough assembly (10).

  10. Laminar heat transfer characteristics of internally finned tube with sinusoidal wavy fin

    NASA Astrophysics Data System (ADS)

    Lin, M.; Tian, L.; Wang, Q. W.

    2011-06-01

    Comparative numerical study of laminar heat transfer characteristics of annular tubes with sinusoidal wavy fins has been conducted both experimentally and numerically with Re = 299-1,475. The uniform heat flux is imposed on the tube outside wall surface. Two tube materials (copper and stainless steel) are considered. It is found that the fluid temperature profile is not linear but convex along the flow direction due to the axial heat conduction in tube wall, and the effects of axial heat conduction on the heat transfer decreases with an increase in Reynolds number or decrease in tube wall thermal conductivity. The axial distributions of local Nusselt number could reach periodically fully developed after 3-5 cycles. The convectional data reduction method based on the traditional method should be improved for tube with high thermal conductivity or low Reynolds numbers, Otherwise, the heat transfer performance of internally finned tube may be underestimated.

  11. Sinusoidal electromagnetic field of 50 hz helps in retaining calcium in tibias of aged rats.

    PubMed

    Khanduja, K L; Syal, N

    2003-03-01

    Effect of 50Hz sinusoidal electromagnetic field (SEMF) on normal bone physiology was evaluated in young and old female and male Wistar rats. Exposure to SEMF resulted in increased 45Ca retention in tibias of aged animals only. Levels of serum calcium in young female and male rats were significantly less than in respective aged rats. These were further decreased after 4 weeks of SEMF exposure. SEMF exposure did not change the serum calcium levels in aged rats, and inorganic phosphates in young and aged animals. Similarly, the levels of tartrate resistant acid and alkaline phosphatase were significantly decreased in young rats, whereas the levels remained unchanged in aged rats of either sex. The results revealed that SEMF of 1mT can prevent bone calcium loss due to aging in animals. PMID:15267147

  12. El Perfil Sinusoidal del Jet HH 31 en la Protoestrella IRAS 042482612

    NASA Astrophysics Data System (ADS)

    Ferrero, L. V.; Gómez, M. N.

    In this contribution we study the HH 31 jet; associated with the Class I proto-star; IRAS 042482612 (age 10 yrs); in the Taurus molecular cloud. We use mid-infrared images; taken by Spitzer and WISE; to analyze the sinusoidal or S-shape chain of knots (or EGOs) that delineate the jet. The binarity of the central source naturally explains the wiggling jet. The orbital period is 2.7 times the estimated dynamical time of the jet. The spatial difference between knots agrees with time elapse expected between quasi-periodic FU Orionis events; suggesting that central star might have experimented this type of events several times since its birth. FULL TEXT IN SPANISH

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

    NASA Astrophysics Data System (ADS)

    Rizwan Sadiq, I. Mohammed

    2012-03-01

    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.

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

    PubMed

    Sadiq, I Mohammed Rizwan

    2012-03-01

    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

  15. Effect of sinusoidal density modulations on stimulated Raman and Brillouin scattering instabilities

    NASA Astrophysics Data System (ADS)

    Depierreux, Sylvie; Bandulet, Heidi; Lewis, Kevin; Labaune, Christine; Baldis, Hector; Michard, Alain

    2003-10-01

    Stimulated Raman (SRS) and Brillouin (SBS) scattering are expected to reach significant levels in the long and homogeneous plasmas that will be produced with the NIF and LMJ. We have performed an experiment as to measure modifications of SRS and SBS of a 1.053 μ m interaction beam when a small scale ( ˜6μ m) sinusoidal modulation of the density is imposed along the laser propagation axis. These density perturbations can affect the SRS and SBS development as they break the plasma homogeneity and can couple to the stimulated electron plasma waves (EPW) and ion acoustic waves (IAW). Diagnostics of the SRS and SBS activities include time, space and spectrally resolved analysis of the light Thomson scattered off stimulated EPW and IAW as well as backscattering measurements.

  16. Real-time detection of musical onsets with linear prediction and sinusoidal modeling

    NASA Astrophysics Data System (ADS)

    Glover, John; Lazzarini, Victor; Timoney, Joseph

    2011-12-01

    Real-time musical note onset detection plays a vital role in many audio analysis processes, such as score following, beat detection and various sound synthesis by analysis methods. This article provides a review of some of the most commonly used techniques for real-time onset detection. We suggest ways to improve these techniques by incorporating linear prediction as well as presenting a novel algorithm for real-time onset detection using sinusoidal modelling. We provide comprehensive results for both the detection accuracy and the computational performance of all of the described techniques, evaluated using Modal, our new open source library for musical onset detection, which comes with a free database of samples with hand-labelled note onsets.

  17. Propagation of sinusoidal electrical waves along the spinal cord during a fictive motor task.

    PubMed

    Cuellar, Carlos A; Tapia, Jesus A; Juárez, Victoria; Quevedo, Jorge; Linares, Pablo; Martínez, Lourdes; Manjarrez, Elias

    2009-01-21

    We present for the first time direct electrophysiological evidence of the phenomenon of traveling electrical waves produced by populations of interneurons within the spinal cord. We show that, during a fictive rhythmic motor task, scratching, an electrical field potential of spinal interneurons takes the shape of a sinuous wave, "sweeping" the lumbosacral spinal cord rostrocaudally with a mean speed of approximately 0.3 m/s. We observed that traveling waves and scratching have the same cycle duration and that duration of the flexor phase, but not of the extensor phase, is highly correlated with the cycle duration of the traveling waves. Furthermore, we found that the interneurons from the deep dorsal horn and the intermediate nucleus can generate the spinal traveling waves, even in the absence of motoneuronal activity. These findings show that the sinusoidal field potentials generated during fictive scratching could be a powerful tool to disclose the organization of central pattern generator networks. PMID:19158305

  18. Charge-pump voltage converter

    DOEpatents

    Brainard, John P.; Christenson, Todd R.

    2009-11-03

    A charge-pump voltage converter for converting a low voltage provided by a low-voltage source to a higher voltage. Charge is inductively generated on a transfer rotor electrode during its transit past an inductor stator electrode and subsequently transferred by the rotating rotor to a collector stator electrode for storage or use. Repetition of the charge transfer process leads to a build-up of voltage on a charge-receiving device. Connection of multiple charge-pump voltage converters in series can generate higher voltages, and connection of multiple charge-pump voltage converters in parallel can generate higher currents. Microelectromechanical (MEMS) embodiments of this invention provide a small and compact high-voltage (several hundred V) voltage source starting with a few-V initial voltage source. The microscale size of many embodiments of this invention make it ideally suited for MEMS- and other micro-applications where integration of the voltage or charge source in a small package is highly desirable.

  19. Energy stored and dissipated in skeletal muscle basement membranes during sinusoidal oscillations.

    PubMed Central

    Tidball, J G

    1986-01-01

    We subjected single skeletal muscle cells from frog semitendinosus to sinusoidal oscillations that simulated the strain experienced as the cells near the end of passive extension and begin active contraction in slow swimming. Other cells from which the basement membrane was removed by enzymatic and mechanical procedures were tested identically. Effectiveness of the basement membrane removal technique was evaluated by electron microscopy, by an electrophoretic and lectin-binding assay for depletion of cell surface glycoproteins, and by confirmation by means of electrophoretic and immunologic analyses that major intracellular, cytoskeletal proteins were not disrupted. Measurements of maximum stress, maximum strain, and phase lag between these maxima enabled the complex modulus (dynamic stiffness) and loss tangent (relative viscous losses to elastic energy storage) to be calculated for each mechanically tested preparation. We also calculated the amounts of energy stored and dissipated in each preparation. These calculations indicate that cells with intact basement membranes have complex moduli significantly greater than those of cells without basement membranes, and that cells with basement membrane store significantly more elastic energy than basement membrane depleted cells. However, when subjected to identical sinusoidal strains, energy dissipation in cells with intact basement membranes is over three times greater than dissipation in cells without basement membrane. The relative magnitudes of energy losses to energy storage, called the specific loss, is nearly three times greater for intact cells than for basement membrane depleted cells. Basement membranes may thereby serve as a brake for slowing passive extension of muscle before contraction begins. Images FIGURE 2 FIGURE 3 FIGURE 4 FIGURE 5 PMID:3801573

  20. Flow pattern and pressure drop of vertical upward gas-liquid flow in sinusoidal wavy channels

    SciTech Connect

    Nilpueng, Kitti; Wongwises, Somchai

    2006-06-15

    Flow patterns and pressure drop of upward liquid single-phase flow and air-water two-phase flow in sinusoidal wavy channels are experimentally studied. The test section is formed by a sinusoidal wavy wall of 1.00 m length with a wave length of 67.20mm, an amplitude of 5.76mm. Different phase shifts between the side walls of the wavy channel of 0{sup o}, 90{sup o} and 180{sup o} are investigated. The flow phenomena, which are bubbly flow, slug flow, churn flow, and dispersed bubbly flow are observed and recorded by high-speed camera. When the phase shifts are increased, the onset of the transition from the bubbly flow to the churn flow shifts to a higher value of superficial air velocity, and the regions of the slug flow and the churn flow are smaller. In other words, the regions of the bubbly flow and the dispersed bubbly flow are larger as the phase shift increases. The slug flow pattern is only found in the test sections with phase shifts of 0{sup o} and 90{sup o}. Recirculating gas bubbles are always found in the troughs of the corrugations. The recirculating is higher when the phase shifts are larger. The relationship between the two-phase multipliers calculated from the measured pressure drops, and the Martinelli parameter is compared with the Lockhart-Martinelli correlation. The correlation in the case of turbulent-turbulent condition is shown to fit the data very well for the phase shift of 0{sup o} but shows greater deviation when the phase shifts are higher. (author)

  1. P-selectin expression in a colon tumor model exposed by sinusoidal electromagnetic fields

    PubMed Central

    TUNCEL, HANDAN; SHIMAMOTO, FUMIO; ÇIRAKOĞLU, AYŞE; KORPINAR, MEHMET ALI; KALKAN, TUNAYA

    2013-01-01

    P-selectin is mainly involved in the initial process of tumor cell adhesion to platelets. The aim of the present study was to determine the expression level of P-selectin in a colon tumor model affected by sinusoidal electromagnetic fields (SMF). Male Wistar albino rats aged 2-2.5 months were used. The animals were divided into the I [N-Methyl-N-Nitrosurea (MNU)], II (SMF-MNU), III (SMF) and IV (control) groups. The rats were housed five per polycarbonate cage. Sixty milligrams of MNU was dissolved in 6 ml sterile 0.9% NaCl. Prepared solutions were administered intra rectally (i.r.) to the 1st and 3rd groups as 0.2 ml/per animal. The same procedure was applied to the 2nd and 4th groups, although 0.2 ml/per animal sterile isotonic solution was administered instead. This procedure was repeated once a week for 10 weeks. Following the administration of MNU, the 2nd and 3rd groups were exposed to a sinusoidal magnetic field (SMF, 50 Hz, 5 mT) for 6 h/day for 8 months. P-selectin expression of the four groups of rat colon tissues was determined using immunohistochemistry on paraffin sections. The labeled streptavidin biotin method was performed. Fisher’s exact test was used for differences between proportions. Results showed that there was no statistically significant (P>0.05) change in the expression level of P-selectin. However, this result should be verified by both in vivo and in vitro experiments to determine the effects of the magnetic fields on P-selectin. PMID:24648955

  2. Note: Improving low-light-level image detection sensitivity with higher speed using auxiliary sinusoidal light signal

    NASA Astrophysics Data System (ADS)

    Tang, Hongying; Yu, Zhengtao

    2015-06-01

    An improved active imaging method, which upgraded the detection sensitivity by applying an auxiliary sawtooth wave light signal, was reported. Nevertheless, such method sacrificed the imaging speed. To speed up imaging, a sinusoidal light signal is used instead and superposed with the undetectable low-light-level signal on the image sensor. After acquiring a superimposed image set in one sine wave cycle, an unbiased low-light-level image estimation is obtained by using least-square optimization. Through probabilistic analysis and experimental study, we demonstrate that the sinusoidal signal could improve the detection sensitivity 1/3 faster than the sawtooth wave signal.

  3. Spatial frequency doubling - Retinal or central. [visual illusion

    NASA Technical Reports Server (NTRS)

    Richards, W.; Felton, T. B.

    1973-01-01

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

  4. Instantaneous frequency based newborn EEG seizure characterisation

    NASA Astrophysics Data System (ADS)

    Mesbah, Mostefa; O'Toole, John M.; Colditz, Paul B.; Boashash, Boualem

    2012-12-01

    The electroencephalogram (EEG), used to noninvasively monitor brain activity, remains the most reliable tool in the diagnosis of neonatal seizures. Due to their nonstationary and multi-component nature, newborn EEG seizures are better represented in the joint time-frequency domain than in either the time domain or the frequency domain. Characterising newborn EEG seizure nonstationarities helps to better understand their time-varying nature and, therefore, allow developing efficient signal processing methods for both modelling and seizure detection and classification. In this article, we used the instantaneous frequency (IF) extracted from a time-frequency distribution to characterise newborn EEG seizures. We fitted four frequency modulated (FM) models to the extracted IFs, namely a linear FM, a piecewise-linear FM, a sinusoidal FM, and a hyperbolic FM. Using a database of 30-s EEG seizure epochs acquired from 35 newborns, we were able to show that, depending on EEG channel, the sinusoidal and piecewise-linear FM models best fitted 80-98% of seizure epochs. To further characterise the EEG seizures, we calculated the mean frequency and frequency span of the extracted IFs. We showed that in the majority of the cases (>95%), the mean frequency resides in the 0.6-3 Hz band with a frequency span of 0.2-1 Hz. In terms of the frequency of occurrence of the four seizure models, the statistical analysis showed that there is no significant difference( p = 0.332) between the two hemispheres. The results also indicate that there is no significant differences between the two hemispheres in terms of the mean frequency ( p = 0.186) and the frequency span ( p = 0.302).

  5. Excitation of voltage oscillations in an induction voltage adder

    NASA Astrophysics Data System (ADS)

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

    2009-07-01

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

  6. E-beam high voltage switching power supply

    DOEpatents

    Shimer, Daniel W.; Lange, Arnold C.

    1996-01-01

    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.

  7. E-beam high voltage switching power supply

    DOEpatents

    Shimer, D.W.; Lange, A.C.

    1996-10-15

    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.

  8. Development of a fast voltage control method for electrostatic accelerators

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    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.

  9. Separating inverse spin Hall voltage and spin rectification voltage by inverting spin injection direction

    NASA Astrophysics Data System (ADS)

    Zhang, Wenxu; Peng, Bin; Han, Fangbin; Wang, Qiuru; Soh, Wee Tee; Ong, Chong Kim; Zhang, Wanli

    2016-03-01

    We develop a method for universally resolving the important issue of separating the inverse spin Hall effect (ISHE) from the spin rectification effect (SRE) signal. This method is based on the consideration that the two effects depend on the spin injection direction: The ISHE is an odd function of the spin injection direction while the SRE is independent on it. Thus, the inversion of the spin injection direction changes the ISHE voltage signal, while the SRE voltage remains. It applies generally to analyzing the different voltage contributions without fitting them to special line shapes. This fast and simple method can be used in a wide frequency range and has the flexibility of sample preparation.

  10. An expert system to analyze high frequency dependent data for the space shuttle main engine turbopumps

    NASA Technical Reports Server (NTRS)

    Garcia, Raul C., Jr.

    1987-01-01

    The prototype expert system ADDAMX identifies selected sinusoid frequencies from spectral data graphs as speed frequencies and harmonics from each turbopump, frequency feed through from one turbopump to another, frequencies generated by turbopump bearings, pseudo 3N for the phase 2 high pressure fuel turbopump, and electrical noise. ADDAMX does the analysis in an interactive or batch mode and the results can be displayed on the screen or hardcopy.

  11. Experimental Study on DBD Plasma Actuator with Combination of AC and Nanosecond Pulse Voltage

    NASA Astrophysics Data System (ADS)

    Kimura, Taichi; Udagawa(Takashima, Keisuke; Yamasaki, Hiroyuki

    In the last decade, a Dielectric Barrier Discharge (DBD) plasma actuator driven by combination voltage of AC and nanosecond pulse has been studied. The combined-voltage-driven plasma actuator increased the body force effect, which induces wall jet and flow suction, by overlapping nanosecond pulse voltage while DBD plasma actuator driven by nanosecond pulses is a flow control actuator generating compression waves due to pulse heating, which allows us to do active flow control in high speed flow reported up to Mach number 0.7. In this study, DBD plasma actuator driven by combination voltage of sinusoidal AC and nanosecond pulse has been experimentally studied. Time-averaged net thrust and cycle-averaged power consumption of actuator were characterized by electrical weight balance and charge-voltage cycle of DBD plasma actuator, respectively. The plasma actuator thrust driven with the combination voltage enhanced its thrust with pulse repetition rate increase. Energy consumption in the actuator was controlled by varying AC phase when the nanosecond pulse is applied. Therefore, the thrust and power consumption in the actuator was almost independently controlled by pulse repetition rate and pulse imposed phase.

  12. Growth mechanisms study of microcrystalline silicon deposited by SiH{sub 4}/H{sub 2} plasma using tailored voltage waveforms

    SciTech Connect

    Bruneau, B. Johnson, E. V.; Wang, J.; Dornstetter, J.-C.

    2014-02-28

    The use of Tailored Voltage Waveforms is a technique wherein one uses non-sinusoidal waveforms with a period equivalent to RF frequencies to excite a plasma. It has been shown to be an effective technique to decouple maximum Ion Bombardment Energy (IBE) from the ion flux at the surface of the electrodes. In this paper, we use it for the first time as a way to scan through the IBE in order to study the growth mechanism of hydrogenated microcrystalline silicon using a SiH{sub 4}/H{sub 2} chemistry. We find that at critical energies, a stepwise increase in the amorphous to microcrystalline transition thickness is observed, as detected by Real Time Spectroscopic Ellipsometry. The same energy thresholds (30 eV and 70 eV) are found to be very influential on the final surface morphology of the samples, as observed by Atomic Force Microscopy. These thresholds correspond to SiH{sub x}{sup +} bulk displacement (30 eV) and H{sub x}{sup +} (70 eV) surface displacement energies. A model is therefore proposed to account for the impact of these ions on the morphology of μc-Si:H growth.

  13. High voltage dc--dc converter with dynamic voltage regulation and decoupling during load-generated arcs

    DOEpatents

    Shimer, D.W.; Lange, A.C.

    1995-05-23

    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.

  14. High voltage dc-dc converter with dynamic voltage regulation and decoupling during load-generated arcs

    DOEpatents

    Shimer, Daniel W.; Lange, Arnold C.

    1995-01-01

    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.

  15. Electronic Voltage and Current Transformers Testing Device

    PubMed Central

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

    2012-01-01

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

  16. Electronic voltage and current transformers testing device.

    PubMed

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

    2012-01-01

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

  17. High voltage feedthrough bushing

    DOEpatents

    Brucker, John P.

    1993-01-01

    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.

  18. High voltage isolation transformer

    NASA Technical Reports Server (NTRS)

    Clatterbuck, C. H.; Ruitberg, A. P. (Inventor)

    1985-01-01

    A high voltage isolation transformer is provided with primary and secondary coils separated by discrete electrostatic shields from the surfaces of insulating spools on which the coils are wound. The electrostatic shields are formed by coatings of a compound with a low electrical conductivity which completely encase the coils and adhere to the surfaces of the insulating spools adjacent to the coils. Coatings of the compound also line axial bores of the spools, thereby forming electrostatic shields separating the spools from legs of a ferromagnetic core extending through the bores. The transformer is able to isolate a high constant potential applied to one of its coils, without the occurrence of sparking or corona, by coupling the coatings, lining the axial bores to the ferromagnetic core and by coupling one terminal of each coil to the respective coating encasing the coil.

  19. Basement membrane of mouse bone marrow sinusoids shows distinctive structure and proteoglycan composition: a high resolution ultrastructural study.

    PubMed

    Inoue, S; Osmond, D G

    2001-11-01

    Venous sinusoids in bone marrow are the site of a large-scale traffic of cells between the extravascular hemopoietic compartment and the blood stream. The wall of the sinusoids consists solely of a basement membrane interposed between a layer of endothelial cells and an incomplete covering of adventitial cells. To examine its possible structural specialization, the basement membrane of bone marrow sinusoids has now been examined by high resolution electron microscopy of perfusion-fixed mouse bone marrow. The basement membrane layer was discontinuous, consisting of irregular masses of amorphous material within a uniform 60-nm-wide space between apposing endothelial cells and adventitial cell processes. At maximal magnifications, the material was resolved as a random arrangement of components lacking the "cord network" formation seen in basement membranes elsewhere. Individual components exhibited distinctive ultrastructural features whose molecular identity has previously been established. By these morphological criteria, the basement membrane contained unusually abundant chondroitin sulfate proteoglycan (CSPG) revealed by 3-nm-wide "double tracks," and moderate amounts of both laminin as dense irregular coils and type IV collagen as 1-1.5-nm-wide filaments, together with less conspicuous amounts of amyloid P forming pentagonal frames. In contrast, 4.5-5-nm-wide "double tracks" characteristic of heparan sulfate proteoglycan (HSPG) were absent. The findings demonstrate that, in comparison with "typical" basement membranes in other tissues, the bone marrow sinusoidal basement membrane is uniquely specialized in several respects. Its discontinuous nature, lack of network organization, and absence of HSPG, a molecule that normally helps to maintain membrane integrity, may facilitate disassembly and reassembly of basement membrane material in concert with movements of adventitial cell processes as maturing hemopoietic cells pass through the sinusoidal wall: the exceptionally large quantity of CSPG may represent a reservoir of CD44 receptor for use in hemopoiesis. PMID:11596011

  20. Expression of cell-cell and cell-matrix adhesion proteins by sinusoidal endothelial cells in the normal and cirrhotic human liver.

    PubMed Central

    Couvelard, A.; Scoazec, J. Y.; Feldmann, G.

    1993-01-01

    We compared the expression of cell-cell and cell-matrix adhesion proteins by sinusoidal endothelial cells in normal human liver, in which the endothelial lining of hepatic sinusoids is discontinuous and devoid of basement membrane, and in cirrhosis, during which sinusoids might undergo a process of capillarization and acquire a continuous lining and a typical basement membrane. In normal liver, sinusoidal endothelial cells displayed a very restricted repertory of cell-adhesion molecules: the intercellular adhesion molecules PECAM-1 and CD34 were undetectable and only two integrins, alpha 1 beta 1 and alpha 5 beta 1, were present, whereas the laminin receptors alpha 6 beta 1 and alpha 2 beta 1 were undetectable and the beta 3 integrins were faintly expressed. In capillarized sinusoids, sinusoidal endothelial cells displayed striking changes in their repertory of cell-adhesion molecules, including the expression of PECAM-1 protein and messenger RNAs and the induction of the laminin receptors alpha 6 beta 1 and alpha 2 beta 1. Such changes co-localized with subendothelial laminin deposits. In conclusion, normal sinusoidal endothelial cells express a distinctive set of cell-adhesion molecules, adapted to their structural and microenvironmental characteristics, and this repertory is dramatically modified during sinusoidal capillarization, possibly as a consequence of the concomitant matrix changes. Images Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 PMID:8362973