WorldWideScience

Sample records for oscillation electronic resource

  1. Oscillator clustering in a resource distribution chain

    DEFF Research Database (Denmark)

    Postnov, D.; Sosnovtseva, Olga; Mosekilde, Erik

    2005-01-01

    separate the inherent dynamics of the individual oscillator from the properties of the coupling network. Illustrated by examples from microbiological population dynamics, renal physiology, and electronic oscillator theory, we show how competition for primary resources in a resource distribution chain leads...

  2. Non-linear phenomena in electronic systems consisting of coupled single-electron oscillators

    International Nuclear Information System (INIS)

    Kikombo, Andrew Kilinga; Hirose, Tetsuya; Asai, Tetsuya; Amemiya, Yoshihito

    2008-01-01

    This paper describes non-linear dynamics of electronic systems consisting of single-electron oscillators. A single-electron oscillator is a circuit made up of a tunneling junction and a resistor, and produces simple relaxation oscillation. Coupled with another, single electron oscillators exhibit complex behavior described by a combination of continuous differential equations and discrete difference equations. Computer simulation shows that a double-oscillator system consisting of two coupled oscillators produces multi-periodic oscillation with a single attractor, and that a quadruple-oscillator system consisting of four oscillators also produces multi-periodic oscillation but has a number of possible attractors and takes one of them determined by initial conditions

  3. Downshift of electron plasma oscillations in the electron foreshock region

    International Nuclear Information System (INIS)

    Fuselier, S.A.

    1984-01-01

    Electron plasma oscillations in the Earth's electron foreshock region are observed to shift above and below the local electron plasma frequency. As plasma oscillations shift from the plasma frequency, their bandwidth increases and their wavelength decreases. Observations of plasma oscillations well below the plasma frequency are correlated with times when ISEE-I is far downstream of the electron foreshock boundary. Although wavelengths of plasma oscillations below the plasma frequency satisfy klambda/sub De/ approx. = 1, the Doppler shift due to the motion of the solar wind is not sufficient to produce the observed frequency shifts. A beam-plasma interaction with beam velocities on the order of the electron thermal velocity is suggested as an explanation for plasma oscillations above and below the plasma frequency. Frequency, bandwidth, and wavelength changes predicted from the beam-plasma interaction are in good agreement with the observed characteristics of plasma oscillations in the foreshock region

  4. Downshift of electron plasma oscillations in the electron foreshock region

    International Nuclear Information System (INIS)

    Fuselier, S.A.; Gurnett, D.A.; Fitzenreiter, R.J.; NASA, Goddard Space Flight Center, Greenbelt, MD)

    1985-01-01

    Electron plasma oscillations in the earth's electron foreshock region are observed to shift above and below the local electron plasma frequency. As plasma oscillations shift downward from the plasma frequency, their bandwidth increases and their wavelength decreases. Observations of plasma oscillations well below the plasma frequency are correlated with times when ISEE 1 is far downstream of the electron foreshock boundary. Although wavelengths of plasma oscillations below the plasma frequency satisfy k x lambda-De approximately 1 the Doppler shift due to the motion of the solar wind is not sufficient to produce the observed frequency shifts. A beam-plasma interaction with beam velocities on the order of the electron thermal velocity is suggested as an explanation for plasma oscillations above and below the plasma frequency. Frequency, bandwidth, and wavelength changes predicted from the beam-plasma interaction are in good agreement with the observed characteristics of plasma oscillations in the foreshock region. 28 references

  5. Quantum electronics maser amplifiers and oscillators

    CERN Document Server

    Fain, V M; Sanders, J H

    2013-01-01

    Quantum Electronics, Volume 2: Maser Amplifiers and Oscillators deals with the experimental and theoretical aspects of maser amplifiers and oscillators which are based on the principles of quantum electronics. It shows how the concepts and equations used in quantum electronics follow from the basic principles of theoretical physics.Comprised of three chapters, this volume begins with a discussion on the elements of the theory of quantum oscillators and amplifiers working in the microwave region, along with the practical achievements in this field. Attention is paid to two-level paramagnetic ma

  6. The Two-Beam Free Electron Laser Oscillator

    CERN Document Server

    Thompson, Neil R

    2004-01-01

    A one-dimensional model of a free-electron laser operating simultaneously with two electron beams of different energies [1] is extended to an oscillator configuration. The electron beam energies are chosen so that an harmonic of the lower energy beam is at the fundamental radiation wavelength of the higher energy beam. Potential benefits over a single-beam free-electron laser oscillator are discussed.

  7. Electromagnetic Radiation Originating from Unstable Electron Oscillations

    DEFF Research Database (Denmark)

    Juul Rasmussen, Jens; Pécseli, Hans

    1975-01-01

    Electromagnetic oscillations in the range 300 – 700 MHz were observed from an unmagnetized argon discharge with an unstable electron velocity distribution function.......Electromagnetic oscillations in the range 300 – 700 MHz were observed from an unmagnetized argon discharge with an unstable electron velocity distribution function....

  8. The Downshift of Electron Plasma Oscillations in the Electron Foreshock Region.

    Science.gov (United States)

    1984-10-10

    Ii D-Ai50 52 THE DOWNSHIFT OF ELECTRON PLASMA OSCILLATIONS IN THE i/1. ELECTRON FORESHOCK R.. (U) I0MM UNIV 10MM CITY DEPT OF PHYSICS AND ASTRONOMY 5...OSCILLATIONS 0 IN THE ELECTRON FORESHOCK REGION In by S. A. Fuselierl, D. A. Gurnett 1 , Ace NTI 0. and R. J. Fitzenreiter 2 DTI I ,3WERSflY o. 06UNDED ISAI...geleasel Ditibto Unlimited 02 1 16 U. of Iowa 84-21 THE DOWNSHIFT OF ELECTRON PLASMA OSCILLATIONSJ / IN THE ELECTRON FORESHOCK REGION t - by Z I S. A

  9. Neutrino oscillations and neutrino-electron scattering

    International Nuclear Information System (INIS)

    Kayser, B.; Rosen, S.P.

    1980-10-01

    Neutrino flavor oscillations can significantly alter the cross section for neutrino-electron scattering. As a result, such oscillations can affect the comparison between existing reactor data and theories of neutral-current processes. They may also lead to strikingly large effects in high-energy accelerator experiments

  10. Awakened Oscillations in Coupled Consumer-Resource Pairs

    Directory of Open Access Journals (Sweden)

    Almaz Mustafin

    2014-01-01

    Full Text Available The paper concerns two interacting consumer-resource pairs based on chemostat-like equations under the assumption that the dynamics of the resource is considerably slower than that of the consumer. The presence of two different time scales enables to carry out a fairly complete analysis of the problem. This is done by treating consumers and resources in the coupled system as fast-scale and slow-scale variables, respectively, and subsequently considering developments in phase planes of these variables, fast and slow, as if they are independent. When uncoupled, each pair has unique asymptotically stable steady state and no self-sustained oscillatory behavior (although damped oscillations about the equilibrium are admitted. When the consumer-resource pairs are weakly coupled through direct reciprocal inhibition of consumers, the whole system exhibits self-sustained relaxation oscillations with a period that can be significantly longer than intrinsic relaxation time of either pair. It is shown that the model equations adequately describe locally linked consumer-resource systems of quite different nature: living populations under interspecific interference competition and lasers coupled via their cavity losses.

  11. Two-electron Rabi oscillations in real-time time-dependent density-functional theory

    International Nuclear Information System (INIS)

    Habenicht, Bradley F.; Tani, Noriyuki P.; Provorse, Makenzie R.; Isborn, Christine M.

    2014-01-01

    We investigate the Rabi oscillations of electrons excited by an applied electric field in several simple molecular systems using time-dependent configuration interaction (TDCI) and real-time time-dependent density-functional theory (RT-TDDFT) dynamics. While the TDCI simulations exhibit the expected single-electron Rabi oscillations at a single resonant electric field frequency, Rabi oscillations in the RT-TDDFT simulations are a two-electron process. The existence of two-electron Rabi oscillations is determined both by full population inversion between field-free molecular orbitals and the behavior of the instantaneous dipole moment during the simulations. Furthermore, the Rabi oscillations in RT-TDDFT are subject to an intensity threshold of the electric field, below which Rabi oscillations do not occur and above which the two-electron Rabi oscillations occur at a broad range of frequencies. It is also shown that at field intensities near the threshold intensity, the field frequency predicted to induce Rabi oscillations by linear response TDDFT only produces detuned Rabi oscillations. Instead, the field frequency that yields the full two-electron population inversion and Rabi oscillation behavior is shown to be the average of single-electron transition frequencies from the ground S 0 state and the doubly-excited S 2 state. The behavior of the two-electron Rabi oscillations is rationalized via two possible models. The first model is a multi-photon process that results from the electric field interacting with the three level system such that three level Rabi oscillations may occur. The second model suggests that the mean-field nature of RT-TDDFT induces paired electron propagation

  12. Electronically tunable RC sinusoidal oscillators

    International Nuclear Information System (INIS)

    Florescu, Valeriu

    2008-01-01

    This paper presents two types of active configurations for realizing electronically tunable RC sinusoidal oscillators. The type-1 network employs two grounded scaled resistances KR 1 and KR 2 , where K is scaling factor. The frequency of oscillation W 0 is controlled conveniently by adjusting K, since W 0 appears in the form W 0 =1/K √ R 1 C 1 R 2 C 2 . For realizing the scaled resistances, an active configuration is proposed, which realizes KR 1 =R 1 /(1+f(V B )), where f(V B ) denotes a function of a controlling voltage V B . Thus the frequency tuning can be effected by controlling a voltage V B . The type-2 oscillator uses two periodically switched conductances. It is shown that the tuning of oscillation frequency can be done by varying the pulse width-to-period ratio (t/T) of the periodically switched conductances. (author)

  13. Reactor oscillator - I - III, Part III - Electronic device

    International Nuclear Information System (INIS)

    Lolic, B.; Jovanovic, S.

    1961-12-01

    This report describes functioning of the reactor oscillator electronic system. Two methods of oscillator operation were discussed. The first method is so called method of amplitude modulation of the reactor power, and the second newer method is phase method. Both methods are planned for the present reactor oscillator

  14. Electron diode oscillators for high-power RF generation

    International Nuclear Information System (INIS)

    Humphries, S.

    1989-01-01

    Feedback oscillators have been used since the invention of the vacuum tube. This paper describes the extension of these familiar circuits to the regime of relativistic electron beam diodes. Such devices have potential application for the generation of high power RF radiation in the range 50-250 MHz, 1-10 GW with 20-60% conversion efficiency. This paper reviews the theory of the oscillator and the results of a design study. Calculations for the four-electrode diode with EGUN and EBQ show that good modulations of 30 kA electron beam at 600 kV can be achieved with moderate field stress on the electrodes. Conditions for oscillation have been studied with an in-house transmission line code. A design for a 7.5 GW oscillator at 200 MHz with 25% conversion efficiency is presented

  15. An electronically tunable current-mode quadrature oscillator using PCAs

    OpenAIRE

    Herencsár, Norbert; Lahiri, Abhirup; Vrba, Kamil; Koton, Jaroslav

    2012-01-01

    The paper presents a new realization of active RC sinusoidal oscillator with electronically tunable condition and frequency of oscillation. As compared to the class of three resistors, two capacitors (3R-2C) based canonic oscillators, the proposed circuit here uses only two resistors and two capacitors as the passive components and still provides non-interactive tuning laws for the condition of oscillation (CO) and the frequency of oscillation (FO). The proposed circuit employs new bipolar pr...

  16. Reactor oscillator - I - III, Part III - Electronic device; Reaktorski oscilator - I-III, III Deo - Elektronski uredjaj

    Energy Technology Data Exchange (ETDEWEB)

    Lolic, B; Jovanovic, S [Institute of Nuclear Sciences Boris Kidric, Laboratorija za fiziku reaktora, Vinca, Beograd (Serbia and Montenegro)

    1961-12-15

    This report describes functioning of the reactor oscillator electronic system. Two methods of oscillator operation were discussed. The first method is so called method of amplitude modulation of the reactor power, and the second newer method is phase method. Both methods are planned for the present reactor oscillator.

  17. Damping of electron center-of-mass oscillation in ultracold plasmas

    International Nuclear Information System (INIS)

    Chen, Wei-Ting; Witte, Craig; Roberts, Jacob L.

    2016-01-01

    Applying a short electric field pulse to an ultracold plasma induces an electron plasma oscillation. This manifests itself as an oscillation of the electron center of mass around the ion center of mass in the ultracold plasma. In general, the oscillation can damp due to either collisionless or collisional mechanisms, or a combination of the both. To investigate the nature of oscillation damping in ultracold plasmas, we developed a molecular dynamics model of the ultracold plasma electrons. Through this model, we found that depending on the neutrality of the ultracold plasma and the size of an applied DC electric field, there are some parameter ranges where the damping is primarily collisional and some primarily collisionless. We conducted experiments to compare the measured damping rate with theory predictions and found them to be in good agreement. Extension of our measurements to different parameter ranges should enable studies for strong-coupling influence on electron-ion collision rates.

  18. A search for oscillations of muon-neutrinos to electron-neutrinos

    CERN Document Server

    Procario, Michael

    1986-01-01

    The author has searched in the heavy liquid bubble chamber BEBC for electron neutrino charge current events which could arise from oscillation of the muon neutrinos (average energy ∼1.5 GeV) obtained with a low energy proton beam at the CERN PS targeted 825 m upstream from BEBC. The appearance of electron neutrino CC interactions provides a sensitive indication of nu/sub μ/ → nu/sub e/ oscillation. The author observed 460 muon neutrino CC events and 4 electron neutrino CC events with an estimated background of 3.5 electron neutrino CC events. Using the likelihood ratio method to test the oscillation hypothesis, the author finds no evidence for nu/sub μ/ → nu/sub e/ oscillation and set the limits δm2 ≤ 0.13 eV2 (maximal mixing) and sin22theta ≤ 0.018 for δm2 = 3 eV2 at 90% confidence level

  19. Electronic oscillations in a hot plasma due the non-Maxwellian velocity distributions

    International Nuclear Information System (INIS)

    Dias, L.A.V.; Nakamura, Y.

    1977-01-01

    In a completely ionized hot plasma, with a non-Maxwellian electron velocity distribution, it is shown that, depending on the electron temperature, oscillations may occur at the elctron plasma and gyro frequencies. For three different electron velocity distributions, it is shown the oscillations dependency on the temperature. This situation occurs in the ionospheric plasma when artificially heated by HF radio waves. If the distribution is Maxwellian, the oscillation only occur near the electron plasma frequency [pt

  20. Conductance oscillation in graphene-nanoribbon-based electronic Fabry-Perot resonators

    International Nuclear Information System (INIS)

    Zhang Yong; Han Mei; Shen Linjiang

    2010-01-01

    By using the tight-binding approximation and the Green's function method, the quantum conductance of the Fabry-Perot-like electronic resonators composed of zigzag and metallic armchair edge graphene nanoribbons (GNRs) was studied numerically. Obtained results show that due to Fabry-Perot-like electronic interference, the conductance of the GNR resonators oscillates periodically with the Fermi energy. The effects of disorders and coupling between the electrodes and the GNR on conductance oscillations were explored. It is found that the conductance oscillations appear at the strong coupling and become resonant peaks as the coupling is very weak. It is also found that the strong disorders in the GNR can smear the conductance oscillation periods. In other words, the weak coupling and the strong disorders all can blur the conductance oscillations, making them unclearly distinguished.

  1. particle simulation for electrostatic oscillation of virtual cathode in relativistic electron beams

    International Nuclear Information System (INIS)

    Chen Deming; Wang Min

    1990-01-01

    The virtual cathode oscillation in relativistic electron beams is studied by a 1-D electrostatic particle simulation code with finite-size-particle model. When injection current is less than the space charge limiting current, electron beam propagates stably and transsmits completely. When injection current exceeds the space charge limit, its propagation is unstable, a part of electrons reflect and the other electrons transsmit. The position and potential of the virtual cathode caused by space charge effects oscillate periodically. When the beam current increases, the virtual cathode position closer to the injection plane and its oscillating region gets narrower, the virtual cathode potential decreases and its amplitude increases, the oscillation frequency increases above the beam plasma frequency

  2. Sinusoidal oscillators and waveform generators using modern electronic circuit building blocks

    CERN Document Server

    Senani, Raj; Singh, V K; Sharma, R K

    2016-01-01

    This book serves as a single-source reference to sinusoidal oscillators and waveform generators, using classical as well as a variety of modern electronic circuit building blocks. It provides a state-of-the-art review of a large variety of sinusoidal oscillators and waveform generators and includes a catalogue of over 600 configurations of oscillators and waveform generators, describing their relevant design details and salient performance features/limitations. The authors discuss a number of interesting, open research problems and include a comprehensive collection of over 1500 references on oscillators and non-sinusoidal waveform generators/relaxation oscillators. Offers readers a single-source reference to everything connected to sinusoidal oscillators and waveform generators, using classical as well as modern electronic circuit building blocks; Provides a state-of-the-art review of a large variety of sinusoidal oscillators and waveform generators; Includes a catalog of over 600 configurations of oscillato...

  3. Electronically Tunable Current-Mode Quadrature Oscillator Using Single MCDTA

    Directory of Open Access Journals (Sweden)

    Y. Li

    2010-12-01

    Full Text Available This paper presents a modified current differencing transconductance amlpifier (MCDTA and the MCDTA based quadrature oscillator. The oscillator is current-mode and provides current output from high output impedance terminals. The circuit uses only one MCDTA and two grounded capacitors, and is easy to be integrated. Its oscillation frequency can be tuned electronically by tuning bias currents of MCDTA. Finally, frequency error is analyzed. The results of circuit simulations are in agreement with theory.

  4. The electronic system for mechanical oscillation parameters registration

    Directory of Open Access Journals (Sweden)

    Bulavin L. A.

    2008-08-01

    Full Text Available On the basis of the 8-bit microcontroller Microchip PIC16F630 the digital electronic device for harmonic oscillation parameters registration was developed. The device features are simple electric circuit and high operating speed (response time is less than 10 microseconds. The relevant software for the computer-controlled recording of harmonic oscillation parameters was designed. The device can be used as a part of the experimental setup for consistent fluids rheological parameters measurements.

  5. Control electron beam oscillation regimes in Pierce diode with overcritical current

    International Nuclear Information System (INIS)

    Rempen, I.S.; Khramov, A.E.

    2001-01-01

    The effect of the delayed feedback on the complex oscillation regimes in the electron flux with the overcritical current in the Pierce diode is studied. The possibility of controlling the oscillation regimes through changing the feedback parameters is shown. The finite-dimensional model, describing the behavior of the electron flux in the Pierce diode hydrodynamic model, is constructed. Its behavior under the effect of the delayed feedback is studied [ru

  6. Relaxation oscillations induced by amplitude-dependent frequency in dissipative trapped electron mode turbulence

    International Nuclear Information System (INIS)

    Terry, P.W.; Ware, A.S.; Newman, D.E.

    1994-01-01

    A nonlinear frequency shift in dissipative trapped electron mode turbulence is shown to give rise to a relaxation oscillation in the saturated power density spectrum. A simple non-Markovian closure for the coupled evolution of ion momentum and electron density response is developed to describe the oscillations. From solutions of a nonlinear oscillator model based on the closure, it is found that the oscillation is driven by the growth rate, as modified by the amplitude-dependent frequency shift, with inertia provided by the memory of the growth rate of prior amplitudes. This memory arises from time-history integrals common to statistical closures. The memory associated with a finite time of energy transfer between coupled spectrum components does not sustain the oscillation in the simple model. Solutions of the model agree qualitatively with the time-dependent numerical solutions of the original dissipative trapped electron model, yielding oscillations with the proper phase relationship between the fluctuation energy and the frequency shift, the proper evolution of the wave number spectrum shape and particle flux, and a realistic period

  7. Runaway relativistic electron scattering on the plazma oscillations in tokamak

    International Nuclear Information System (INIS)

    Krasovitskij, V.B.; Razdorski, V.G.

    1980-01-01

    The dynamics of fast electrons in a tolamak plasma with the presence of the constant external electric field have been inveatigated. It is shown that the occurrence of the relativistic electrons ''tail'' of the distribution function is followed by an intensive plasma oscillation swinging under conditions of the anomalous Doppler effect and their large angle scattering in the momentum space. A part of scattered electrons is captured by tokamak inhomogeneous magnetic field and causes the occurrence of a new low frequency alfven instability under conditions of magnetic drift resonance followed by quasilinear diffusion of relativistic electrons along the small radius of the torus. The flux of runaway electrons scattered on plasma oscillations has been found. A nonlinear diffusion equation has been derived for the flux of captured electrons. The equation defines the carrying out of fast particles from the plasma filament center to its periphery depending on the external magnetic field and plasma parameters

  8. Weiss oscillations in the electronic structure of modulated graphene

    International Nuclear Information System (INIS)

    Tahir, M; Sabeeh, K; MacKinnon, A

    2007-01-01

    We present a theoretical study of the electronic structure of modulated graphene in the presence of a perpendicular magnetic field. The density of states and the bandwidth for the Dirac electrons in this system are determined. The appearance of unusual Weiss oscillations in the bandwidth and density of states is the main focus of this work

  9. Self-excitation of microwave oscillations in plasma-assisted slow-wave oscillators by an electron beam with a movable focus

    Science.gov (United States)

    Bliokh, Yu. P.; Nusinovich, G. S.; Shkvarunets, A. G.; Carmel, Y.

    2004-10-01

    Plasma-assisted slow-wave oscillators (pasotrons) operate without external magnetic fields, which makes these devices quite compact and lightweight. Beam focusing in pasotrons is provided by ions, which appear in the device due to the impact ionization of a neutral gas by beam electrons. Typically, the ionization time is on the order of the rise time of the beam current. This means that, during the rise of the current, beam focusing by ions becomes stronger. Correspondingly, a beam of electrons, which was initially diverging radially due to the self-electric field, starts to be focused by ions, and this focus moves towards the gun as the ion density increases. This feature makes the self-excitation of electromagnetic (em) oscillations in pasotrons quite different from practically all other microwave sources where em oscillations are excited by a stationary electron beam. The process of self-excitation of em oscillations has been studied both theoretically and experimentally. It is shown that in pasotrons, during the beam current rise the amount of current entering the interaction space and the beam coupling to the em field vary. As a result, the self-excitation can proceed faster than in conventional microwave sources with similar operating parameters such as the operating frequency, cavity quality-factor and the beam current and voltage.

  10. Electron beam modification of vanadium dioxide oscillators

    Energy Technology Data Exchange (ETDEWEB)

    Belyaev, Maksim; Velichko, Andrey; Putrolaynen, Vadim; Perminov, Valentin; Pergament, Alexander [Petrozavodsk State University, Petrozavodsk (Russian Federation)

    2017-03-15

    The paper presents the results of a study of electron-beam modification (EBM) of VO{sub 2}-switch I-V curve threshold parameters and the self-oscillation frequency of a circuit containing such a switching device. EBM in vacuum is reversible and the parameters are restored when exposed to air at pressure of 150 Pa. At EBM with a dose of 3 C cm{sup -2}, the voltages of switching-on (V{sub th}) and off (V{sub h}), as well as the OFF-state resistance R{sub off}, decrease down to 50% of the initial values, and the oscillation frequency increases by 30% at a dose of 0.7 C cm{sup -2}. Features of physics of EBM of an oscillator are outlined considering the contribution of the metal and semiconductor phases of the switching channel. Controlled modification allows EBM forming of switches with preset parameters. Also, it might be used in artificial oscillatory neural networks for pattern recognition based on frequency shift keying. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  11. Oscillating molecular dipoles require strongly correlated electronic and nuclear motion

    International Nuclear Information System (INIS)

    Chang, Bo Y; Shin, Seokmin; Palacios, Alicia; Martín, Fernando; Sola, Ignacio R

    2015-01-01

    To create an oscillating electric dipole in an homonuclear diatomic cation without an oscillating driver one needs (i) to break the symmetry of the system and (ii) to sustain highly correlated electronic and nuclear motion. Based on numerical simulations in H 2 + we present results for two schemes. In the first one (i) is achieved by creating a superposition of symmetric and antisymmetric electronic states freely evolving, while (ii) fails. In a second scheme, by preparing the system in a dressed state of a strong static field, both conditions hold. We then analyze the robustness of this scheme with respect to features of the nuclear wave function and its intrinsic sources of decoherence. (tutorial)

  12. Adiabatic and non-adiabatic electron oscillations in a static electric field

    International Nuclear Information System (INIS)

    Wahlberg, C.

    1977-03-01

    The influence of a static electric field on the oscillations of a one-dimensional stream of electrons is investigated. In the weak field limit the oscillations are adiabatic and mode coupling negligible, but becomes significant if the field is tronger. The latter effect is believed to be of importance for the stability of e.g. potential double layers

  13. Electronically Tunable Quadrature Sinusoidal Oscillator with Equal Output Amplitudes during Frequency Tuning Process

    Directory of Open Access Journals (Sweden)

    Den Satipar

    2017-01-01

    Full Text Available A new configuration of voltage-mode quadrature sinusoidal oscillator is proposed. The proposed oscillator employs two voltage differencing current conveyors (VDCCs, two resistors, and two grounded capacitors. In this design, the use of multiple/dual output terminal active building block is not required. The tuning of frequency of oscillation (FO can be done electronically by adjusting the bias current of active device without affecting condition of oscillation (CO. The electronic tuning can be done by controlling the bias current using a digital circuit. The amplitude of two sinusoidal outputs is equal when the frequency of oscillation is tuned. This makes the sinusoidal output voltages meet good total harmonic distortions (THD. Moreover, the proposed circuit can provide the sinusoidal output current with high impedance which is connected to external load or to another circuit without the use of buffer device. To confirm that the oscillator can generate the quadrature sinusoidal output signal, the experimental results using VDCC constructed from commercially available ICs are also included. The experimental results agree well with theoretical anticipation.

  14. Deep saturated Free Electron Laser oscillators and frozen spikes

    Energy Technology Data Exchange (ETDEWEB)

    Ottaviani, P.L. [ENEA - Centro Ricerche Bologna, via Martiri di Monte Sole, 4, IT 40129, Bologna (Italy); Pagnutti, S., E-mail: simonetta.pagnutti@enea.it [ENEA - Centro Ricerche Bologna, via Martiri di Monte Sole, 4, IT 40129, Bologna (Italy); Dattoli, G., E-mail: giuseppe.dattoli@enea.it [ENEA - Centro Ricerche Frascati, via E. Fermi, 45, IT 00044, Frascati, Roma (Italy); Sabia, E., E-mail: elio.sabia@enea.it [ENEA - Centro Ricerche Frascati, via E. Fermi, 45, IT 00044, Frascati, Roma (Italy); Petrillo, V., E-mail: vittoria.petrillo@mi.infn.it [Universita' degli Studi di Milano, via Celoria 16, IT 20133, Milano (Italy); INFN - Mi, via Celoria 16, IT 20133, Milano (Italy); Slot, P.J.M. van der, E-mail: p.j.m.vanderslot@utwente.nl [Mesa+ Institute for Nanotechnology, University of Twente, P.O.Box 217, 7500 AE, Enschede (Netherlands); Biedron, S., E-mail: sandra.biedron@colostate.edu [Department of Electrical and Computer Engineering Colorado State University (United States); Milton, S., E-mail: milton@engr.colostate.edu [Department of Electrical and Computer Engineering Colorado State University (United States)

    2016-10-21

    We analyze the behavior of Free Electron Laser (FEL) oscillators operating in the deep saturated regime and point out the formation of sub-peaks of the optical pulse. These are very stable configurations and the sub-peaks are found to have a duration corresponding to the coherence length. We speculate on the physical mechanisms underlying their growth and attempt an identification with natural mode-locked structures in FEL oscillators. Their impact on the intra-cavity nonlinear harmonic generation is also discussed along with the possibility of exploiting them as cavity out-coupler.

  15. Charged particle emission effects on the characteristics of glow discharges with oscillating electrons

    CERN Document Server

    Nikulin, S P

    2001-01-01

    One discusses the effect of selection of charged particles on conditions to maintain and the characteristics of a glow discharge with oscillating electrons. It is shown that there is a pressure dependent optimal level of ion selection when the energy efficiency of ion source reaches its maximum value. It is determined that departure of fast ionizing electrons affects negatively the discharge maintenance wile emission of slow plasma electrons may promote maintenance of a discharge high current shape. It is shown that high efficient electron emission without violation of a discharge stability may take place in a magnetic field due to different nature of spatial distributions of fast and slow particles in discharges with electron oscillation

  16. Electron plasma oscillations in the Venus foreshock

    Science.gov (United States)

    Crawford, G. K.; Strangeway, R. J.; Russell, C. T.

    1990-01-01

    Plasma waves are observed in the solar wind upstream of the Venus bow shock by the Pioneer Venus Orbiter. These wave signatures occur during periods when the interplanetary magnetic field through the spacecraft position intersects the bow shock, thereby placing the spacecraft in the foreshock region. The electron foreshock boundary is clearly evident in the data as a sharp onset in wave activity and a peak in intensity. Wave intensity is seen to drop rapidly with increasing penetration into the foreshock. The peak wave electric field strength at the electron foreshock boundary is found to be similar to terrestrial observations. A normalized wave spectrum was constructed using measurements of the electron plasma frequency and the spectrum was found to be centered about this value. These results, along with polarization studies showing the wave electric field to be field aligned, are consistent with the interpretation of the waves as electron plasma oscillations.

  17. Electron plasma oscillations in the Venus foreshock

    International Nuclear Information System (INIS)

    Crawford, G.K.; Strangeway, R.J.; Russell, C.T.

    1990-01-01

    Plasma waves are observed in the solar wind upstream of the Venus bow shock by the Pioneer Venus Orbiter. These wave signatures occur during periods when the interplanetary magnetic field through the spacecraft position intersects the bow shock, thereby placing the spacecraft in the foreshock region. The electron foreshock boundary is clearly evident in the data as a sharp onset in wave activity and a peak in intensity. Wave intensity is seen to drop rapidly with increasing penetration into the foreshock. The peak wave electric field strength at the electron foreshock boundary is found to be similar to terrestrial observations. A normalized wave spectrum was constructed using measurements of the electron plasma frequency and the spectrum was found to be centered about this value. These results, along with polarization studies showing the wave electric field to be field aligned, are consistent with the interpretation of the waves as electron plasma oscillations

  18. Numerical simulation of electron beam welding with beam oscillations

    Science.gov (United States)

    Trushnikov, D. N.; Permyakov, G. L.

    2017-02-01

    This research examines the process of electron-beam welding in a keyhole mode with the use of beam oscillations. We study the impact of various beam oscillations and their parameters on the shape of the keyhole, the flow of heat and mass transfer processes and weld parameters to develop methodological recommendations. A numerical three-dimensional mathematical model of electron beam welding is presented. The model was developed on the basis of a heat conduction equation and a Navier-Stokes equation taking into account phase transitions at the interface of a solid and liquid phase and thermocapillary convection (Marangoni effect). The shape of the keyhole is determined based on experimental data on the parameters of the secondary signal by using the method of a synchronous accumulation. Calculations of thermal and hydrodynamic processes were carried out based on a computer cluster, using a simulation package COMSOL Multiphysics.

  19. Collective oscillations of electrons when simulating first principles and nature of anomalous drift along the power axis

    International Nuclear Information System (INIS)

    Majorov, S.A.; Tkachev, A.N.; Yakovlenko, S.I.

    1996-01-01

    A hypothesis is proposed that a metastable supercooled state of a classic Coulomb particle system can be conditioned by a quasiresonance interaction of bound electrons with the collective oscillations of plasma electrons. This interaction is especially important when the Kepler frequency is of the order of Langmuir oscillation frequency (which takes place when the electron orbit radius is of the order of average distance between the charges). Based on the simulation it is shown that the typical time of the Coulomb particle system dipole moment oscillations appears to be of the order of the Langmuir oscillation frequency. 10 refs.; 3 figs

  20. Modeling paraxial wave propagation in free-electron laser oscillators

    NARCIS (Netherlands)

    Karssenberg, J.G.; van der Slot, Petrus J.M.; Volokhine, I.; Verschuur, Jeroen W.J.; Boller, Klaus J.

    2006-01-01

    Modeling free-electron laser (FEL) oscillators requires calculation of both the light-beam interaction within the undulator and the light propagation outside the undulator. We have developed a paraxial optical propagation code that can be combined with various existing models of gain media, for

  1. Electronic Resource Management and Design

    Science.gov (United States)

    Abrams, Kimberly R.

    2015-01-01

    We have now reached a tipping point at which electronic resources comprise more than half of academic library budgets. Because of the increasing work associated with the ever-increasing number of e-resources, there is a trend to distribute work throughout the library even in the presence of an electronic resources department. In 2013, the author…

  2. Period doubling of azimuthal oscillations on a non-neutral magnetized electron column

    International Nuclear Information System (INIS)

    Boswell, R.W.

    1985-01-01

    The low-frequency azimuthal oscillations on a non-neutral magnetized electron column of very low density are investigated. A perturbation analysis of the slow mode of the rigid rotator equilibrium is developed to illustrate the nature of large-amplitude fundamental-mode oscillations. The results of this theoretical analysis show two important characteristics: firstly, as the perturbation amplitude is increased the wave form ceases to be purely sinusoidal and shows period doubling. Secondly, above a certain threshold, all harmonics of the wave grow and the wave breaks. The results of the former are compared with a simple electron beam experiment and are found to be in good qualitative agreement. (author)

  3. Numerical study of chaotic oscillations in the electron beam with virtual cathode in the external non-uniform magnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    Hramov, Alexander E., E-mail: aeh@nonlin.sgu.r [Faculty of Nonlinear Processes, Saratov State University, 83, Astrakhanskaya, Saratov, 410012 (Russian Federation); Koronovskii, Alexey A., E-mail: alkor@nonlin.sgu.r [Faculty of Nonlinear Processes, Saratov State University, 83, Astrakhanskaya, Saratov, 410012 (Russian Federation); Kurkin, Semen, E-mail: KurkinSA@nonlin.sgu.r [Faculty of Nonlinear Processes, Saratov State University, 83, Astrakhanskaya, Saratov, 410012 (Russian Federation)

    2010-07-05

    In this Letter the results of theoretical investigations of the chaotic microwave oscillator based on the electron beam with a virtual cathode are presented. Nonlinear non-stationary processes in these electron systems are studied by means of numerical analysis of 2.5D model. It was discovered that the non-uniform external magnetic field value controls the dynamical regime of oscillations in the virtual cathode oscillator. The processes of the chaotization of output microwave radiation are described and interpreted from the point of view of the formation and interaction of electron structures (bunches) in the electron beams. The numerical results have shown that the investigated electron system with virtual cathode could be considered as a promising controlled source of wideband chaotic oscillations in the microwave range.

  4. Phase-mixing of Langmuir oscillations in cold electron-positron-ion plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Maity, Chandan [Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700 064 (India)

    2014-07-15

    Space-time evolution of Langmuir oscillations in a cold homogeneous electron-positron-ion plasma has been analyzed by employing a straightforward perturbation expansion method, showing phase-mixing and, thus, wave-breaking of excited oscillations at arbitrary amplitudes. Within an assumption of infinitely massive ions, an approximate phase-mixing time is found to scale as ω{sub pe}t{sub mix}∼[(6/δ{sup 2})((2−α){sup 5/2}/(1−α))]{sup 1/3}, where “δ” and “α” (= n{sub 0i}/n{sub 0e}) are the amplitude of perturbation and the ratio of equilibrium ion density to equilibrium electron density, respectively, and ω{sub pe}∼√(4πn{sub 0e}e{sup 2}/m) is the electron plasma frequency. The results presented on phase-mixing of Langmuir modes in multispecies plasmas are expected to be relevant to laboratory and astrophysical environments.

  5. Electron screening and kinetic-energy oscillations in a strongly coupled plasma

    International Nuclear Information System (INIS)

    Chen, Y.C.; Simien, C.E.; Laha, S.; Gupta, P.; Martinez, Y.N.; Mickelson, P.G.; Nagel, S.B.; Killian, T.C.

    2004-01-01

    We study equilibration of strongly coupled ions in an ultracold neutral plasma produced by photoionizing laser-cooled and trapped atoms. By varying the electron temperature, we show that electron screening modifies the equilibrium ion temperature. Even with few electrons in a Debye sphere, the screening is well described by a model using a Yukawa ion-ion potential. We also observe damped oscillations of the ion kinetic energy that are a unique feature of equilibration of a strongly coupled plasma

  6. Observation of a new plasma regime with stationary electron temperature oscillations on Tore Supra

    International Nuclear Information System (INIS)

    Artaud, J.F.; Giruzzi, G.; Imbeaux, F.; Segui, J.L.; Garbet, X.

    2003-01-01

    This document is a copy of the slides presented on the 9. joint US-European Transport Task Force meeting. The first part is devoted to the experimental observations of a new tokamak plasma regime with stationary electron temperature oscillations. The oscillations appear on ECE spontaneously, sometimes associated with a transition to the LHEP regime. The second part presents an interpretation of these oscillations by analogy with a predator-prey system. (A.L.B.)

  7. Model-independent quantitative measurement of nanomechanical oscillator vibrations using electron-microscope linescans

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Huan; Fenton, J. C.; Chiatti, O. [London Centre for Nanotechnology, University College London, 17–19 Gordon Street, London WC1H 0AH (United Kingdom); Warburton, P. A. [London Centre for Nanotechnology, University College London, 17–19 Gordon Street, London WC1H 0AH (United Kingdom); Department of Electronic and Electrical Engineering, University College London, Torrington Place, London WC1E 7JE (United Kingdom)

    2013-07-15

    Nanoscale mechanical resonators are highly sensitive devices and, therefore, for application as highly sensitive mass balances, they are potentially superior to micromachined cantilevers. The absolute measurement of nanoscale displacements of such resonators remains a challenge, however, since the optical signal reflected from a cantilever whose dimensions are sub-wavelength is at best very weak. We describe a technique for quantitative analysis and fitting of scanning-electron microscope (SEM) linescans across a cantilever resonator, involving deconvolution from the vibrating resonator profile using the stationary resonator profile. This enables determination of the absolute amplitude of nanomechanical cantilever oscillations even when the oscillation amplitude is much smaller than the cantilever width. This technique is independent of any model of secondary-electron emission from the resonator and is, therefore, applicable to resonators with arbitrary geometry and material inhomogeneity. We demonstrate the technique using focussed-ion-beam–deposited tungsten cantilevers of radius ∼60–170 nm inside a field-emission SEM, with excitation of the cantilever by a piezoelectric actuator allowing measurement of the full frequency response. Oscillation amplitudes approaching the size of the primary electron-beam can be resolved. We further show that the optimum electron-beam scan speed is determined by a compromise between deflection of the cantilever at low scan speeds and limited spatial resolution at high scan speeds. Our technique will be an important tool for use in precise characterization of nanomechanical resonator devices.

  8. Electronically induced nuclear transitions - temperature dependence and Rabi oscillations

    International Nuclear Information System (INIS)

    Niez, J.J.

    2002-01-01

    This paper deals with a nucleus electromagnetically coupled with the bound states of its electronic surroundings. It describes the temperature dependence of its dynamics and the onset of potential Rabi oscillations by means of a Master Equation. The latter is generalized in order to account for possible strong resonances. Throughout the paper the approximation schemes are discussed and tested. (authors)

  9. Oscillators - a simple introduction

    DEFF Research Database (Denmark)

    Lindberg, Erik

    2013-01-01

    Oscillators are kernel components of electrical and electronic circuits. Discussion of history, mechanisms and design based on Barkhausens observation. Discussion of a Wien Bridge oscillator based on the question: Why does this circuit oscillate ?......Oscillators are kernel components of electrical and electronic circuits. Discussion of history, mechanisms and design based on Barkhausens observation. Discussion of a Wien Bridge oscillator based on the question: Why does this circuit oscillate ?...

  10. Probing collective oscillation of d-orbital electrons at the nanoscale

    Science.gov (United States)

    Dhall, Rohan; Vigil-Fowler, Derek; Houston Dycus, J.; Kirste, Ronny; Mita, Seiji; Sitar, Zlatko; Collazo, Ramon; LeBeau, James M.

    2018-02-01

    Here, we demonstrate that high energy electrons can be used to explore the collective oscillation of s, p, and d orbital electrons at the nanometer length scale. Using epitaxial AlGaN/AlN quantum wells as a test system, we observe the emergence of additional features in the loss spectrum with the increasing Ga content. A comparison of the observed spectra with ab-initio theory reveals that the origin of these spectral features lies in excitations of 3d-electrons contributed by Ga. We find that these modes differ in energy from the valence electron plasmons in Al1-xGaxN due to the different polarizabilities of the d electrons. Finally, we study the dependence of observed spectral features on the Ga content, lending insights into the origin of these spectral features, and their coupling with electron-hole excitations.

  11. Spin–orbit coupling induced magnetoresistance oscillation in a dc biased two-dimensional electron system

    International Nuclear Information System (INIS)

    Wang, C M; Lei, X L

    2014-01-01

    We study dc-current effects on the magnetoresistance oscillation in a two-dimensional electron gas with Rashba spin-orbit coupling, using the balance-equation approach to nonlinear magnetotransport. In the weak current limit the magnetoresistance exhibits periodical Shubnikov-de Haas oscillation with changing Rashba coupling strength for a fixed magnetic field. At finite dc bias, the period of the oscillation halves when the interbranch contribution to resistivity dominates. With further increasing current density, the oscillatory resistivity exhibits phase inversion, i.e., magnetoresistivity minima (maxima) invert to maxima (minima) at certain values of the dc bias, which is due to the current-induced magnetoresistance oscillation. (paper)

  12. Response of a core coherent density oscillation on electron cyclotron resonance heating in Heliotron J plasma

    Science.gov (United States)

    Kobayashi, T.; Kobayashi, S.; Lu, X. X.; Kenmochi, N.; Ida, K.; Ohshima, S.; Yamamoto, S.; Kado, S.; Kokubu, D.; Nagasaki, K.; Okada, H.; Minami, T.; Otani, Y.; Mizuuchi, T.

    2018-01-01

    We report properties of a coherent density oscillation observed in the core region and its response to electron cyclotron resonance heating (ECH) in Heliotron J plasma. The measurement was performed using a multi-channel beam emission spectroscopy system. The density oscillation is observed in a radial region between the core and the half radius. The poloidal mode number is found to be 1 (or 2). By modulating the ECH power with 100 Hz, repetition of formation and deformation of a strong electron temperature gradient, which is likely ascribed to be an electron internal transport barrier, is realized. Amplitude and rotation frequency of the coherent density oscillation sitting at the strong electron temperature gradient location are modulated by the ECH, while the poloidal mode structure remains almost unchanged. The change in the rotation velocity in the laboratory frame is derived. Assuming that the change of the rotation velocity is given by the background E × B velocity, a possible time evolution of the radial electric field was deduced.

  13. Electron-beam driven relaxation oscillations in ferroelectric nanodisks

    Energy Technology Data Exchange (ETDEWEB)

    Ng, Nathaniel; Ahluwalia, Rajeev [Institute of High Performance Computing, Singapore 138632 (Singapore); Kumar, Ashok [CSIR-National Physical Laboratory, Delhi 110012 (India); Srolovitz, David J. [Department of Materials Science and Engineering and Department of Mechanical Engineering and Applied Mechanics, University of Pennsylvania, Philadelphia, Pennsylvania 19104 (United States); Chandra, Premala [Department of Physics and Astronomy, Center for Materials Theory, Rutgers University, Piscataway, New Jersey 08854 (United States); Scott, James F. [Department of Physics, Cavendish Laboratory, J. J. Thompson Avenue, Cambridge CB3 0HE (United Kingdom); Department of Chemistry and Department of Physics, University of St. Andrews, St. Andrews YX16 9ST (United Kingdom)

    2015-10-12

    Using a combination of computational simulations, atomic-scale resolution imaging and phenomenological modelling, we examine the underlying mechanism for nanodomain restructuring in lead zirconate titanate nanodisks driven by electron beams. The observed subhertz nanodomain dynamics are identified with relaxation oscillations where the charging/discharging cycle time is determined by saturation of charge traps and nanodomain wall creep. These results are unusual in that they indicate very slow athermal dynamics in nanoscale systems, and possible applications of gated versions are discussed.

  14. Oscillation mode transformation of edge magnetoplasmons in two-dimensional electron system on liquid-helium surface

    International Nuclear Information System (INIS)

    Yamanaka, Shuji; Yayama, Hideki; Arai, Toshikazau; Anju Sawada, Anju; Fukuda, Akira

    2013-01-01

    We measured the resonance spectra of edge magnetoplasmon (EMP) oscillations in a two-dimensional (2D) electron system located on a liquid-helium surface below 1.1 K. Systematic measurements of the resonance frequency and the damping rate as a function of the lateral confinement electric field strength shows clear evidence of the oscillation mode transformation. A pronounced change corresponding to the mode transformation was observed in the damping rate. When 2D electrons are confined in a strong lateral electric field, the damping is weak. As the lateral confinement electric field is reduced below a certain threshold value, an abrupt enhancement of the damping rate is observed. We hypothesize that the weak damping mode in the strong lateral confinement electric field is the compressive density oscillation of the electrons near the edge (conventional EMP) and the strong damping mode in the weak confinement field is the coupled mode of conventional EMP and the boundary displacement wave (BDW). The observation of the strong damping in the BDW-EMP coupled mode is a manifestation of the nearly incompressible feature of strongly interacting classical electrons, which agrees with earlier theoretical predictions.

  15. Electronic Resource Management Systems

    Directory of Open Access Journals (Sweden)

    Mark Ellingsen

    2004-10-01

    Full Text Available Computer applications which deal with electronic resource management (ERM are quite a recent development. They have grown out of the need to manage the burgeoning number of electronic resources particularly electronic journals. Typically, in the early years of e-journal acquisition, library staff provided an easy means of accessing these journals by providing an alphabetical list on a web page. Some went as far as categorising the e-journals by subject and then grouping the journals either on a single web page or by using multiple pages. It didn't take long before it was recognised that it would be more efficient to dynamically generate the pages from a database rather than to continually edit the pages manually. Of course, once the descriptive metadata for an electronic journal was held within a database the next logical step was to provide administrative forms whereby that metadata could be manipulated. This in turn led to demands for incorporating more information and more functionality into the developing application.

  16. A tapered multi-gap multi-aperture pseudospark-sourced electron gun based X-band slow wave oscillator

    Science.gov (United States)

    Kumar, N.; Lamba, R. P.; Hossain, A. M.; Pal, U. N.; Phelps, A. D. R.; Prakash, R.

    2017-11-01

    The experimental study of a tapered, multi-gap, multi-aperture pseudospark-sourced electron gun based X-band plasma assisted slow wave oscillator is presented. The designed electron gun is based on the pseudospark discharge concept and has been used to generate a high current density and high energy electron beam simultaneously. The distribution of apertures has been arranged such that the field penetration potency inside the backspace of the hollow-cathode is different while passing through the tapered gap region. This leads to non-concurrent ignition of the discharge through all the channels which is, in general, quite challenging in the case of multi-aperture plasma cathode electron gun geometries. Multiple and successive hollow cathode phases are reported from this electron gun geometry, which have been confirmed using simulations. This geometry also has led to the achievement of ˜71% fill factor inside the slow wave oscillator for an electron beam of energy of 20 keV and a beam current density in the range of 115-190 A/cm2 at a working argon gas pressure of 18 Pa. The oscillator has generated broadband microwave output in the frequency range of 10-11.7 GHz with a peak power of ˜10 kW for ˜50 ns.

  17. Third harmonic generation by Bloch-oscillating electrons in a quasioptical array

    International Nuclear Information System (INIS)

    Ghosh, A.W.; Wanke, M.C.; Allen, S.J.; Wilkins, J.W.

    1999-01-01

    We compute the third harmonic field generated by Bloch-oscillating electrons in a quasioptical array of superlattices under THz irradiation. The third harmonic power transmitted oscillates with the internal electric field, with nodes associated with Bessel functions in eEd/ℎω. The nonlinear response of the array causes the output power to be a multivalued function of the incident laser power. The output can be optimized by adjusting the frequency of the incident pulse to match one of the Fabry-Pacute erot resonances in the substrate. Within the transmission-line model of the array, the maximum conversion efficiency is 0.1%. copyright 1999 American Institute of Physics

  18. Electronic Resources Management Project Presentation 2012

    KAUST Repository

    Ramli, Rindra M.

    2012-11-05

    This presentation describes the electronic resources management project undertaken by the KAUST library. The objectives of this project is to migrate information from MS Sharepoint to Millennium ERM module. One of the advantages of this migration is to consolidate all electronic resources into a single and centralized location. This would allow for better information sharing among library staff.

  19. Oscillator, neutron modulator

    International Nuclear Information System (INIS)

    Agaisse, R.; Leguen, R.; Ombredane, D.

    1960-01-01

    The authors present a mechanical device and an electronic control circuit which have been designed to sinusoidally modulate the reactivity of the Proserpine atomic pile. The mechanical device comprises an oscillator and a mechanism assembly. The oscillator is made of cadmium blades which generate the reactivity oscillation. The mechanism assembly comprises a pulse generator for cycle splitting, a gearbox and an engine. The electronic device comprises or performs pulse detection, an on-off device, cycle pulse shaping, phase separation, a dephasing amplifier, electronic switches, counting scales, and control devices. All these elements are briefly presented

  20. Origin of fine oscillations in the photoluminescence spectrum of 2-dimensional electron gas formed in AlGaN/GaN high electron mobility transistor structures

    Energy Technology Data Exchange (ETDEWEB)

    Jana, Dipankar, E-mail: dip2602@gmail.com; Porwal, S.; Oak, S. M.; Sharma, T. K., E-mail: tarun@rrcat.gov.in [Semiconductor Physics and Devices Laboratory, Raja Ramanna Centre for Advanced Technology, Indore 452013, Madhya Pradesh (India); Jain, Anubha [Solid State Physics Laboratory, Lucknow Road, New Delhi 110054 (India)

    2015-10-28

    An unambiguous identification of the fine oscillations observed in the low temperature photoluminescence (PL) spectra of AlGaN/GaN based high electron mobility transistor (HEMT) structures is carried out. In literature, such oscillations have been erroneously identified as the sub-levels of 2-dimensional electron gas (2DEG) formed at AlGaN/GaN heterointerface. Here, the origin of these oscillations is probed by performing the angle dependent PL and reflectivity measurements under identical conditions. Contrary to the reports available in literature, we find that the fine oscillations are not related to 2DEG sub-levels. The optical characteristics of these oscillations are mainly governed by an interference phenomenon. In particular, peculiar temperature dependent redshift and excitation intensity dependent blueshift, which have been interpreted as the characteristics of 2DEG sub-levels in HEMT structures by other researchers, are understood by invoking the wavelength and temperature dependence of the refractive index of GaN within the framework of interference phenomenon. The results of other researchers are also consistently explained by considering the fine oscillatory features as the interference oscillations.

  1. PRINCIPLES OF CONTENT FORMATION EDUCATIONAL ELECTRONIC RESOURCE

    Directory of Open Access Journals (Sweden)

    О Ю Заславская

    2017-12-01

    Full Text Available The article considers modern possibilities of information and communication technologies for the design of electronic educational resources. The conceptual basis of the open educational multimedia system is based on the modular architecture of the electronic educational resource. The content of the electronic training module can be implemented in several versions of the modules: obtaining information, practical exercises, control. The regularities in the teaching process in modern pedagogical theory are considered: general and specific, and the principles for the formation of the content of instruction at different levels are defined, based on the formulated regularities. On the basis of the analysis, the principles of the formation of the electronic educational resource are determined, taking into account the general and didactic patterns of teaching.As principles of the formation of educational material for obtaining information for the electronic educational resource, the article considers: the principle of methodological orientation, the principle of general scientific orientation, the principle of systemic nature, the principle of fundamentalization, the principle of accounting intersubject communications, the principle of minimization. The principles of the formation of the electronic training module of practical studies in the article include: the principle of systematic and dose based consistency, the principle of rational use of study time, the principle of accessibility. The principles of the formation of the module for monitoring the electronic educational resource can be: the principle of the operationalization of goals, the principle of unified identification diagnosis.

  2. Implementing CORAL: An Electronic Resource Management System

    Science.gov (United States)

    Whitfield, Sharon

    2011-01-01

    A 2010 electronic resource management survey conducted by Maria Collins of North Carolina State University and Jill E. Grogg of University of Alabama Libraries found that the top six electronic resources management priorities included workflow management, communications management, license management, statistics management, administrative…

  3. Reactor oscillator - I - III, Part I; Reaktorski oscilator - I-III, I Deo

    Energy Technology Data Exchange (ETDEWEB)

    Lolic, B [Institute of Nuclear Sciences Boris Kidric, Laboratorija za fiziku reaktora, Vinca, Beograd (Serbia and Montenegro)

    1961-12-15

    Project 'Reactor oscillator' covers the following activities: designing reactor oscillators for reactors RA and RB with detailed engineering drawings; constructing and mounting of the oscillator; designing and constructing the appropriate electronic equipment for the oscillator; measurements at the RA and RB reactors needed for completing the oscillator construction.

  4. Managing electronic resources a LITA guide

    CERN Document Server

    Weir, Ryan O

    2012-01-01

    Informative, useful, current, Managing Electronic Resources: A LITA Guide shows how to successfully manage time, resources, and relationships with vendors and staff to ensure personal, professional, and institutional success.

  5. J-PARC Press Release: Electron neutrino oscillation detected at T2K

    CERN Multimedia

    T2K Press Office

    2011-01-01

    Tsukuba, Japan, June 15, 2011. The T2K experiment, whose primary purpose is to study neutrino interactions at a large distance from their source, has detected 6 electron neutrino candidate events based on the data collected before March 11, 2011. For the first time, it was possible to observe an indication that muon neutrinos are able to transform into electron neutrinos over a distance of 295 km through the quantum mechanical phenomena of neutrino flavor oscillations.   The Super-Kamiokande detector, in Japan. © 2011, High Energy Accelerator Research Organization, KEK. The T2K experiment is searching for the neutrino oscillation phenomena, where particular types of neutrinos transform into other types of neutrinos. These observations help determine neutrino masses, as well elucidating the uncharted nature of neutrinos, such as the relationship among three neutrino generations (types). T2K aims at the world’s best sensitivity by detecting neutrinos with the Super-Kamiokande d...

  6. Global plasma oscillations in electron internal transport barriers in TCV

    Energy Technology Data Exchange (ETDEWEB)

    Udintsev, V S; Sauter, O; Asp, E; Fable, E; Goodman, T P; Turri, G; Graves, J P; Zucca, C [Association Euratom-Confederation Suisse, EPFL/SB/CRPP, Station 13, CH-1015, Lausanne (Switzerland); Scarabosio, A [Max-Planck Institut fuer Plasmaphysik, IPP-EURATOM Association, Garching (Germany); Zhuang, G [Huazhong University of Science and Technology, Wuhan, Hubei (China)

    2008-12-15

    In the Tokamak a Configuration Variable (TCV) (Hofmann F et al1994 Plasma Phys. Control. Fusion 36 B277), global plasma oscillations have been discovered in fully non-inductively driven plasmas featuring electron internal transport barriers (ITB) with strong ECRH/ECCD. These oscillations are linked to the destabilization and stabilization of MHD modes near the foot of the ITB and can lead to large oscillations of the total plasma current and line-averaged density, among others. They are intrinsically related to the fact that ITBs have large pressure gradients in a region of low magnetic shear. Therefore, the ideal MHD limit is relatively low and infernal modes can be unstable. Depending on the proximity to the ideal limit, small crashes or resistive modes can appear which affect the time evolution of the discharge. Being near marginal stability, the modes can self-stabilize due to the modification of the pressure gradient and local q-profile. The plasma recovers good confinement, reverses shear and the ITB builds up, until a new MHD mode is destabilized. TCV results show that this cycling behaviour can be controlled by modifying the current density or the pressure profiles, either with Ohmic current density perturbation or by modifying the ECH/ECCD power. It is demonstrated that many observations such as q {>=} 2 sawteeth, beta collapses, minor disruptions and oscillation regimes in ITBs can be assigned to the same physics origin: the proximity to the infernal mode stability limit.

  7. Global plasma oscillations in electron internal transport barriers in TCV

    Science.gov (United States)

    Udintsev, V. S.; Sauter, O.; Asp, E.; Fable, E.; Goodman, T. P.; Turri, G.; Graves, J. P.; Scarabosio, A.; Zhuang, G.; Zucca, C.; TCV Team

    2008-12-01

    In the Tokamak à Configuration Variable (TCV) (Hofmann F et al1994 Plasma Phys. Control. Fusion 36 B277), global plasma oscillations have been discovered in fully non-inductively driven plasmas featuring electron internal transport barriers (ITB) with strong ECRH/ECCD. These oscillations are linked to the destabilization and stabilization of MHD modes near the foot of the ITB and can lead to large oscillations of the total plasma current and line-averaged density, among others. They are intrinsically related to the fact that ITBs have large pressure gradients in a region of low magnetic shear. Therefore, the ideal MHD limit is relatively low and infernal modes can be unstable. Depending on the proximity to the ideal limit, small crashes or resistive modes can appear which affect the time evolution of the discharge. Being near marginal stability, the modes can self-stabilize due to the modification of the pressure gradient and local q-profile. The plasma recovers good confinement, reverses shear and the ITB builds up, until a new MHD mode is destabilized. TCV results show that this cycling behaviour can be controlled by modifying the current density or the pressure profiles, either with Ohmic current density perturbation or by modifying the ECH/ECCD power. It is demonstrated that many observations such as q >= 2 sawteeth, beta collapses, minor disruptions and oscillation regimes in ITBs can be assigned to the same physics origin: the proximity to the infernal mode stability limit.

  8. On some practical consideration of the electron beam breakup transit time oscillator

    International Nuclear Information System (INIS)

    Kwan, T.J.T.

    1992-01-01

    The electron beam breakup transit time oscillator (BTO) makes use of the interaction between an electron beam and the azimuthally azimuthally asymmetric transverse magnetic mode (TM 110 ) of a cavity to facilitate the exchange of energy between them. Linear theory has shown a large growth rate in the regime where space-charge effects can be ignored. In this study, we have investigated the non-ideal elements in the BTO and evaluated their effects accordingly. The practical issues under consideration are electron beam quality, energy, and space-charge potential. Our calculations indicate only a modest unfavorable scalings with respect to these parameters

  9. Neutrino oscillation study in the muon neutrino → electron neutrino channel at the Brookhaven accelerator

    International Nuclear Information System (INIS)

    Astier, P.

    1987-09-01

    The E816 experiment described in this thesis is devoted to a neutrino oscillation search at the Brookhaven AGS. The method used here is to look with a fine grained calorimeter for the appearence of electron neutrino in a muon neutrino beam. After recalling the theoretical treatment of the neutrino mass problem, the experimental phenomenology of massive neutrinos and more specifically neutrino oscillations is reviewed. The experiment itself is then extensively described, both on the technical side (detector, beam, simulation) and on the analysis side. In particular the statistical separation of the electromagnetic showers from electrons - our signal - and from photons - our background - treated in detail. The present analysis is based on 2/3 of the final statistics and it leads to the - preliminary - observation of an electron excess in the neutrino interactions yielding 19 ± 15.6 (stat) ± 7 (syst) [fr

  10. Mesoscopic chaos mediated by Drude electron-hole plasma in silicon optomechanical oscillators

    Science.gov (United States)

    Wu, Jiagui; Huang, Shu-Wei; Huang, Yongjun; Zhou, Hao; Yang, Jinghui; Liu, Jia-Ming; Yu, Mingbin; Lo, Guoqiang; Kwong, Dim-Lee; Duan, Shukai; Wei Wong, Chee

    2017-01-01

    Chaos has revolutionized the field of nonlinear science and stimulated foundational studies from neural networks, extreme event statistics, to physics of electron transport. Recent studies in cavity optomechanics provide a new platform to uncover quintessential architectures of chaos generation and the underlying physics. Here, we report the generation of dynamical chaos in silicon-based monolithic optomechanical oscillators, enabled by the strong and coupled nonlinearities of two-photon absorption induced Drude electron–hole plasma. Deterministic chaotic oscillation is achieved, and statistical and entropic characterization quantifies the chaos complexity at 60 fJ intracavity energies. The correlation dimension D2 is determined at 1.67 for the chaotic attractor, along with a maximal Lyapunov exponent rate of about 2.94 times the fundamental optomechanical oscillation for fast adjacent trajectory divergence. Nonlinear dynamical maps demonstrate the subharmonics, bifurcations and stable regimes, along with distinct transitional routes into chaos. This provides a CMOS-compatible and scalable architecture for understanding complex dynamics on the mesoscopic scale. PMID:28598426

  11. Low-pressure glow discharges with oscillating electrons in different electrode systems

    International Nuclear Information System (INIS)

    Bersenev, V.V.; Gavriolv, N.V.; Nikulin, S.P.

    1995-01-01

    One of the main applications of low - pressure glow discharges is the development on their basis of charged - particle beam sources. The use of glow discharges with oscillating electrons, which can operate stably in the voltage and pressure range to the left of the left branch of Pashen's curve, shows promise, because the decrease in critical pressure p 0 , below which the discharge operation becomes impossible, in the discharge system of a source promotes an increase in the electrical strength of its accelerating system. This, in its turn, makes possible the expansion of the operation range of accelerating voltages. This experimental investigation of glow discharges in such well - known systems with oscillating electrons, as Hollow Cathode (HC), Penning's System (PS) and Inverse Magnetron (IM), is aimed at revealing the system operating at the lowest pressure. Besides, both common features and peculiarities of discharge operation in these systems are discussed. Though there is an extensive amount of published information covering all the specified discharges, the carrying out of such investigation is justified, since a comparative analysis of results obtained by different authors is hampered by various conditions of their experiments

  12. The Oscillator Principle of Nature

    DEFF Research Database (Denmark)

    Lindberg, Erik

    2012-01-01

    Oscillators are found on all levels in Nature. The general oscillator concept is defined and investigated. Oscillators may synchronize into fractal patterns. Apparently oscillators are the basic principle in Nature. The concepts of zero and infinite are discussed. Electronic manmade oscillators...

  13. Observing Muon Neutrino to Electron Neutrino Oscillations in the NOνA Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Xin, Tian [Iowa State U.

    2016-01-01

    Neutrino oscillations offers an insight on new physics beyond the Standard Model. The three mixing angles (θ12, θ13 and θ23) and the two mass splittings (Δm2 and Αm2 ) have been measured by different neutrino oscillation experiments. Some other parameters including the mass ordering of different neutrino mass eigenstates and the CP violation phase are still unknown. NOνA is a long-baseline accelerator neutrino experiment, using neutrinos from the NuMI beam at Fermilab. The experiment is equipped with two functionally identical detectors about 810 kilometers apart and 14 mrad off the beam axis. In this configuration, the muon neutrinos from the NuMI beam reach the disappearance maximum in the far detector and a small fraction of that oscillates into electron neutrinos. The sensitivity to the mass ordering and CP viola- tion phase determination is greately enhanced. This thesis presents the νeappearance analysis using the neutrino data collected with the NOνA experiment between February 2014 and May 2015, which corresponds to 3.45 ×1020 protons-on-target (POT). The νe appearance analysis is performed by comparing the observed νe CC-like events to the estimated background at the far detector. The total background is predicted to be 0.95 events with 0.89 originated from beam events and 0.06 from cosmic ray events. The beam background is obtained by extrapolating near detector data through different oscillation channels, while the cosmic ray background is calculated based on out-of-time NuMI trigger data. A total of 6 electron neutrino candidates are observed in the end at the far detector which represents 3.3 σ excess over the predicted background. The NOνA result disfavors inverted mass hierarchy for δcp ϵ [0, 0.6π] at 90% C.L.

  14. Probing collective oscillation of d -orbital electrons at the nanoscale

    Energy Technology Data Exchange (ETDEWEB)

    Dhall, Rohan [Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695, USA; Vigil-Fowler, Derek [National Renewable Energy Laboratory, Golden, Colorado 80401, USA; Houston Dycus, J. [Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695, USA; Kirste, Ronny [Adroit Materials, Inc., Cary, North Carolina 27518, USA; Mita, Seiji [Adroit Materials, Inc., Cary, North Carolina 27518, USA; Sitar, Zlatko [Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695, USA; Collazo, Ramon [Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695, USA; LeBeau, James M. [Adroit Materials, Inc., Cary, North Carolina 27518, USA

    2018-02-05

    Here, we demonstrate that high energy electrons can be used to explore the collective oscillation of s, p, and d orbital electrons at the nanometer length scale. Using epitaxial AlGaN/AlN quantum wells as a test system, we observe the emergence of additional features in the loss spectrum with the increasing Ga content. A comparison of the observed spectra with ab-initio theory reveals that the origin of these spectral features lies in excitations of 3d-electrons contributed by Ga. We find that these modes differ in energy from the valence electron plasmons in Al1-xGaxN due to the different polarizabilities of the d electrons. Finally, we study the dependence of observed spectral features on the Ga content, lending insights into the origin of these spectral features, and their coupling with electron-hole excitations.

  15. Effect of external magnetic field on critical current for the onset of virtual cathode oscillations in relativistic electron beams

    International Nuclear Information System (INIS)

    Hramov, Alexander; Koronovskii, Alexey; Morozov, Mikhail; Mushtakov, Alexander

    2008-01-01

    In this Letter we research the space charge limiting current value at which the oscillating virtual cathode is formed in the relativistic electron beam as a function of the external magnetic field guiding the beam electrons. It is shown that the space charge limiting (critical) current decreases with growth of the external magnetic field, and that there is an optimal induction value of the magnetic field at which the critical current for the onset of virtual cathode oscillations in the electron beam is minimum. For the strong external magnetic field the space charge limiting current corresponds to the analytical relation derived under the assumption that the motion of the electron beam is one-dimensional [D.J. Sullivan, J.E. Walsh, E. Coutsias, in: V.L. Granatstein, I. Alexeff (Eds.), Virtual Cathode Oscillator (Vircator) Theory, in: High Power Microwave Sources, vol. 13, Artech House Microwave Library, 1987, Chapter 13]. Such behavior is explained by the characteristic features of the dynamics of electron space charge in the longitudinal and radial directions in the drift space at the different external magnetic fields

  16. Electronic motion in the pre-oscillation phase of a smooth bore magnetron

    International Nuclear Information System (INIS)

    Garelis, E.; Hickman, R.B.

    1979-01-01

    The calculation of the electronic motion in the pre-oscillation phase of a smooth bore magnetron is the problem of calculating the electronic motion in the region between two concentric cylinders with an applied radial electric field and a constant axial B/sub z/ magnetic field. The inner cylinder represents the electron emitting cathode and the outer cylinder represents the anode. The emission is assumed to be space charge limited. This results in an electronic cloud surrounding the cathode. The radial velocity of the electrons is limited by the space charge and in addition the axial magnetic field tends to curve the path of the electrons so that they return to the cathode. Consequently, the electronic orbit extends to some distance r 0 from the cathode and for values of the radius r > r 0 exists a charge free region. The model assumes relativistic electronic motion with self-consistent magnetic fields. The magnetic flux is assumed to be conserved; i.e., conducting cylindrical walls

  17. Quantum-mechanical analysis of low-gain free-electron laser oscillators

    Science.gov (United States)

    Fares, H.; Yamada, M.; Chiadroni, E.; Ferrario, M.

    2018-05-01

    In the previous classical theory of the low-gain free-electron laser (FEL) oscillators, the electron is described as a point-like particle, a delta function in the spatial space. On the other hand, in the previous quantum treatments, the electron is described as a plane wave with a single momentum state, a delta function in the momentum space. In reality, an electron must have statistical uncertainties in the position and momentum domains. Then, the electron is neither a point-like charge nor a plane wave of a single momentum. In this paper, we rephrase the theory of the low-gain FEL where the interacting electron is represented quantum mechanically by a plane wave with a finite spreading length (i.e., a wave packet). Using the concepts of the transformation of reference frames and the statistical quantum mechanics, an expression for the single-pass radiation gain is derived. The spectral broadening of the radiation is expressed in terms of the spreading length of an electron, the relaxation time characterizing the energy spread of electrons, and the interaction time. We introduce a comparison between our results and those obtained in the already known classical analyses where a good agreement between both results is shown. While the correspondence between our results and the classical results are shown, novel insights into the electron dynamics and the interaction mechanism are presented.

  18. Optimization of power output and study of electron beam energy spread in a Free Electron Laser oscillator

    CERN Document Server

    Abramovich, A; Efimov, S; Gover, A; Pinhasi, Y; Yahalom, A

    2001-01-01

    Design of a multi-stage depressed collector for efficient operation of a Free Electron Laser (FEL) oscillator requires knowledge of the electron beam energy distribution. This knowledge is necessary to determine the voltages of the depressed collector electrodes that optimize the collection efficiency and overall energy conversion efficiency of the FEL. The energy spread in the electron beam is due to interaction in the wiggler region, as electrons enter the interaction region at different phases relative to the EM wave. This interaction can be simulated well by a three-dimensional simulation code such as FEL3D. The main adjustable parameters that determine the electron beam energy spread after interaction are the e-beam current, the initial beam energy, and the quality factor of the resonator out-coupling coefficient. Using FEL3D, we study the influence of these parameters on the available radiation power and on the electron beam energy distribution at the undulator exit. Simulations performed for I=1.5 A, E...

  19. Effect of beam oscillation on borated stainless steel electron beam welds

    Energy Technology Data Exchange (ETDEWEB)

    RajaKumar, Guttikonda [Tagore Engineering College, Chennai (India). Dept. of Mechanical Engineering; Ram, G.D. Janaki [Indian Institute of Technology (IIT), Chennai (India). Dept. of Metallurgical and Materials Engineering; Rao, S.R. Koteswara [SSN College of Engineering, Chennai (India). Mechanical Engineering

    2015-07-01

    Borated stainless steels are used in nuclear power plants to control neutron criticality in reactors as control rods, shielding material, spent fuel storage racks and transportation casks. In this study, bead on plate welds were made using gas tungsten arc welding (GTAW) and electron beam welding (EBW) processes. Electron beam welds made using beam oscillation technique exhibited higher tensile strength values compared to that of GTA welds. Electron beam welds were found to show fine dendritic microstructure while GTA welds exhibited larger dendrites. While both processes produced defect free welds, GTA welds are marked by partially melted zone (PMZ) where the hardness is low. EBW obviate the PMZ failure due to low heat input and in case of high heat input GTA welding process failure occurs in the PMZ.

  20. Effect of beam oscillation on borated stainless steel electron beam welds

    International Nuclear Information System (INIS)

    RajaKumar, Guttikonda; Ram, G.D. Janaki; Rao, S.R. Koteswara

    2015-01-01

    Borated stainless steels are used in nuclear power plants to control neutron criticality in reactors as control rods, shielding material, spent fuel storage racks and transportation casks. In this study, bead on plate welds were made using gas tungsten arc welding (GTAW) and electron beam welding (EBW) processes. Electron beam welds made using beam oscillation technique exhibited higher tensile strength values compared to that of GTA welds. Electron beam welds were found to show fine dendritic microstructure while GTA welds exhibited larger dendrites. While both processes produced defect free welds, GTA welds are marked by partially melted zone (PMZ) where the hardness is low. EBW obviate the PMZ failure due to low heat input and in case of high heat input GTA welding process failure occurs in the PMZ.

  1. Gender Analysis Of Electronic Information Resource Use: The Case ...

    African Journals Online (AJOL)

    Based on the findings the study concluded that access and use of electronic information resources creates a “social digital divide” along gender lines. The study ... Finally, the library needs to change its marketing strategies on the availability of electronic information resources to increase awareness of these resources.

  2. Users satisfaction with electronic information resources and services ...

    African Journals Online (AJOL)

    This study investigated users satisfaction on the use of electronic information resources and services in MTN Net libraries in ABU & UNIBEN. Two objectives and one null hypotheses were formulated and tested with respect to the users' satisfaction on electronic information resources and services in MTN Net libraries in ...

  3. Nonlinear dynamics and chaotization of oscillations of a virtual cathode in an annular electron beam in a uniform external magnetic field

    International Nuclear Information System (INIS)

    Kurkin, S. A.; Koronovski, A. A.; Hramov, A. E.

    2009-01-01

    Results are presented from a numerical study of the effect of an external magnetic field on the conditions and mechanisms for the formation of a virtual cathode in a relativistic electron beam. Characteristic features of the nonlinear dynamics of an electron beam with a virtual cathode are considered when the external magnetic field is varied. Various mechanisms are investigated by which the virtual cathode oscillations become chaotic and their spectrum becomes a multifrequency spectrum, thereby complicating the dynamics of the vircator system. A general mechanism for chaotization of the oscillations of a virtual cathode in a vircator system is revealed: the electron structures that form in an electron beam interact by means of a common space charge field to give rise to additional internal feedback. That the oscillations of a virtual cathode change from the chaotic to the periodic regime is due to the suppression of the mechanism for forming secondary electron structures.

  4. Dipole term and first derivative at K=0 of the generalized oscillator strength of He by keV electron impact

    International Nuclear Information System (INIS)

    Backx, C.; Tol, R.R.; Wight, G.R.; Wiel, M.J. van der

    1975-01-01

    An approximate method is described for obtaining the derivative to K 2 of the generalized oscillator strength for keV electron scattering at zero momentum transfer, over a large range of energy losses. The measured data enable the reduction of the systematical uncertainty in the derivation of optical oscillator strengths to below 1%. Results are presented for He over the spectral range of 19 to 65 eV. The data for the derivation are in satisfactory agreement with earlier electron scattering results at lower impact energy and extend over a sufficient range to allow the application of a sum rule for this term of the generalized oscillator strength. (Auth.)

  5. Oscillating heat pipes

    CERN Document Server

    Ma, Hongbin

    2015-01-01

    This book presents the fundamental fluid flow and heat transfer principles occurring in oscillating heat pipes and also provides updated developments and recent innovations in research and applications of heat pipes. Starting with fundamental presentation of heat pipes, the focus is on oscillating motions and its heat transfer enhancement in a two-phase heat transfer system. The book covers thermodynamic analysis, interfacial phenomenon, thin film evaporation,  theoretical models of oscillating motion and heat transfer of single phase and two-phase flows, primary  factors affecting oscillating motions and heat transfer,  neutron imaging study of oscillating motions in an oscillating heat pipes, and nanofluid’s effect on the heat transfer performance in oscillating heat pipes.  The importance of thermally-excited oscillating motion combined with phase change heat transfer to a wide variety of applications is emphasized. This book is an essential resource and learning tool for senior undergraduate, gradua...

  6. Nonlinear theory for axisymmetric self-similar two-dimensional oscillations of electrons in cold plasma with constant proton background

    Science.gov (United States)

    Osherovich, V. A.; Fainberg, J.

    2018-01-01

    We consider simultaneous oscillations of electrons moving both along the axis of symmetry and also in the direction perpendicular to the axis. We derive a system of three nonlinear ordinary differential equations which describe self-similar oscillations of cold electrons in a constant proton density background (np = n0 = constant). These three equations represent an exact class of solutions. For weak nonlinear conditions, the frequency spectra of electric field oscillations exhibit split frequency behavior at the Langmuir frequency ωp0 and its harmonics, as well as presence of difference frequencies at low spectral values. For strong nonlinear conditions, the spectra contain peaks at frequencies with values ωp0(n +m √{2 }) , where n and m are integer numbers (positive and negative). We predict that both spectral types (weak and strong) should be observed in plasmas where axial symmetry may exist. To illustrate possible applications of our theory, we present a spectrum of electric field oscillations observed in situ in the solar wind by the WAVES experiment on the Wind spacecraft during the passage of a type III solar radio burst.

  7. Two-dimensional collective electron magnetotransport, oscillations, and chaos in a semiconductor superlattice.

    Science.gov (United States)

    Bonilla, L L; Carretero, M; Segura, A

    2017-12-01

    When quantized, traces of classically chaotic single-particle systems include eigenvalue statistics and scars in eigenfuntions. Since 2001, many theoretical and experimental works have argued that classically chaotic single-electron dynamics influences and controls collective electron transport. For transport in semiconductor superlattices under tilted magnetic and electric fields, these theories rely on a reduction to a one-dimensional self-consistent drift model. A two-dimensional theory based on self-consistent Boltzmann transport does not support that single-electron chaos influences collective transport. This theory agrees with existing experimental evidence of current self-oscillations, predicts spontaneous collective chaos via a period doubling scenario, and could be tested unambiguously by measuring the electric potential inside the superlattice under a tilted magnetic field.

  8. Two-dimensional collective electron magnetotransport, oscillations, and chaos in a semiconductor superlattice

    Science.gov (United States)

    Bonilla, L. L.; Carretero, M.; Segura, A.

    2017-12-01

    When quantized, traces of classically chaotic single-particle systems include eigenvalue statistics and scars in eigenfuntions. Since 2001, many theoretical and experimental works have argued that classically chaotic single-electron dynamics influences and controls collective electron transport. For transport in semiconductor superlattices under tilted magnetic and electric fields, these theories rely on a reduction to a one-dimensional self-consistent drift model. A two-dimensional theory based on self-consistent Boltzmann transport does not support that single-electron chaos influences collective transport. This theory agrees with existing experimental evidence of current self-oscillations, predicts spontaneous collective chaos via a period doubling scenario, and could be tested unambiguously by measuring the electric potential inside the superlattice under a tilted magnetic field.

  9. Organizational matters of competition in electronic educational resources

    Directory of Open Access Journals (Sweden)

    Ирина Карловна Войтович

    2015-12-01

    Full Text Available The article examines the experience of the Udmurt State University in conducting competitions of educational publications and electronic resources. The purpose of such competitions is to provide methodological support to educational process. The main focus is on competition of electronic educational resources. The technology of such contests is discussed through detailed analysis of the main stages of the contest. It is noted that the main task of the preparatory stage of the competition is related to the development of regulations on competition and the definition of criteria for selection of the submitted works. The paper also proposes a system of evaluation criteria of electronic educational resources developed by members of the contest organizing committee and jury members. The article emphasizes the importance of not only the preparatory stages of the competition, but also measures for its completion, aimed at training teachers create quality e-learning resources.

  10. Digital power and performance analysis of inkjet printed ring oscillators based on electrolyte-gated oxide electronics

    Science.gov (United States)

    Cadilha Marques, Gabriel; Garlapati, Suresh Kumar; Dehm, Simone; Dasgupta, Subho; Hahn, Horst; Tahoori, Mehdi; Aghassi-Hagmann, Jasmin

    2017-09-01

    Printed electronic components offer certain technological advantages over their silicon based counterparts, like mechanical flexibility, low process temperatures, maskless and additive manufacturing possibilities. However, to be compatible to the fields of smart sensors, Internet of Things, and wearables, it is essential that devices operate at small supply voltages. In printed electronics, mostly silicon dioxide or organic dielectrics with low dielectric constants have been used as gate isolators, which in turn have resulted in high power transistors operable only at tens of volts. Here, we present inkjet printed circuits which are able to operate at supply voltages as low as ≤2 V. Our transistor technology is based on lithographically patterned drive electrodes, the dimensions of which are carefully kept well within the printing resolutions; the oxide semiconductor, the electrolytic insulator and the top-gate electrodes have been inkjet printed. Our inverters show a gain of ˜4 and 2.3 ms propagation delay time at 1 V supply voltage. Subsequently built 3-stage ring oscillators start to oscillate at a supply voltage of only 0.6 V with a frequency of ˜255 Hz and can reach frequencies up to ˜350 Hz at 2 V supply voltage. Furthermore, we have introduced a systematic methodology for characterizing ring oscillators in the printed electronics domain, which has been largely missing. Benefiting from this procedure, we are now able to predict the switching capacitance and driver capability at each stage, as well as the power consumption of our inkjet printed ring oscillators. These achievements will be essential for analyzing the performance and power characteristics of future inkjet printed digital circuits.

  11. Reactor oscillator - I - III, Part I

    International Nuclear Information System (INIS)

    Lolic, B.

    1961-12-01

    Project 'Reactor oscillator' covers the following activities: designing reactor oscillators for reactors RA and RB with detailed engineering drawings; constructing and mounting of the oscillator; designing and constructing the appropriate electronic equipment for the oscillator; measurements at the RA and RB reactors needed for completing the oscillator construction

  12. CHALLENGES OF ELECTRONIC INFORMATION RESOURCES IN ...

    African Journals Online (AJOL)

    This paper discusses the role of policy for proper and efficient library services in the electronic era. It points out some of the possible dangers of embarking in electronic resources without a proper focus at hand. Thus, it calls for today's librarians and policy makers to brainstorm and come up with working policies suitable to ...

  13. Observation of Quasichanneling Oscillations

    International Nuclear Information System (INIS)

    Wistisen, T. N.; Mikkelsen, R. E.; Uggerhoj, University I.; Wienands, University; Markiewicz, T. W.

    2017-01-01

    Here, we report on the first experimental observations of quasichanneling oscillations, recently seen in simulations and described theoretically. Although above-barrier particles penetrating a single crystal are generally seen as behaving almost as in an amorphous substance, distinct oscillation peaks nevertheless appear for particles in that category. The quasichanneling oscillations were observed at SLAC National Accelerator Laboratory by aiming 20.35 GeV positrons and electrons at a thin silicon crystal bent to a radius of R = 0.15 m, exploiting the quasimosaic effect. For electrons, two relatively faint quasichanneling peaks were observed, while for positrons, seven quasichanneling peaks were clearly identified.

  14. Phase mixing of transverse oscillations in the linear and nonlinear regimes for IFR relativistic electron beam propagation

    International Nuclear Information System (INIS)

    Shokair, I.R.

    1991-01-01

    Phase mixing of transverse oscillations changes the nature of the ion hose instability from an absolute to a convective instability. The stronger the phase mixing, the faster an electron beam reaches equilibrium with the guiding ion channel. This is important for long distance propagation of relativistic electron beams where it is desired that transverse oscillations phase mix within a few betatron wavelengths of injection and subsequently an equilibrium is reached with no further beam emittance growth. In the linear regime phase mixing is well understood and results in asymptotic decay of transverse oscillations as 1/Z 2 for a Gaussian beam and channel system, Z being the axial distance measured in betatron wavelengths. In the nonlinear regime (which is likely mode of propagation for long pulse beams) results of the spread mass model indicate that phase mixing is considerably weaker than in the regime. In this paper we consider this problem of phase mixing in the nonlinear regime. Results of the spread mass model will be shown along with a simple analysis of phase mixing for multiple oscillator models. Particle simulations also indicate that phase mixing is weaker in nonlinear regime than in the linear regime. These results will also be shown. 3 refs., 4 figs

  15. Coupled opto electronic oscillator with a passively mode locked extended cavity diode laser

    International Nuclear Information System (INIS)

    Lee, Jeongmin; Jang, Gwang Hoon; Yoon, Duseong; Song, Minsoo; Yoon, Tai Hyun

    2008-01-01

    An opto electronic oscillator(OEO)has very unique properties compared to the conventional quartz based microwave oscillators in that its oscillation frequency is determined by the beat note frequency of a phase coherent optical frequency comb generated as a side bands to an optical single mode carrier by using an electro optic modulator (EOM)or a direct current modulation of a semiconductor laser. Recently, a different type of OEO called a COEO has been demonstrated, where the optical carrier in the OEO system has been replaced by a mode locked laser so that an EOM or a direct current modulation are no longer necessary, but has potentially a much lower phase noise thanks to the high Q value of the optical frequency comb due to the mode locking mechanism. In this paper, we propose and demonstrate a COEO based on a passively mode locked ECDL at 852nm in which the fourth harmonic of the repetition frequency of the ECDL matched exactly the ground state hyperfine splitting frequency of the Cs atoms

  16. Coupled opto electronic oscillator with a passively mode locked extended cavity diode laser

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jeongmin; Jang, Gwang Hoon; Yoon, Duseong; Song, Minsoo; Yoon, Tai Hyun [Korea Univ., Seoul (Korea, Republic of)

    2008-11-15

    An opto electronic oscillator(OEO)has very unique properties compared to the conventional quartz based microwave oscillators in that its oscillation frequency is determined by the beat note frequency of a phase coherent optical frequency comb generated as a side bands to an optical single mode carrier by using an electro optic modulator (EOM)or a direct current modulation of a semiconductor laser. Recently, a different type of OEO called a COEO has been demonstrated, where the optical carrier in the OEO system has been replaced by a mode locked laser so that an EOM or a direct current modulation are no longer necessary, but has potentially a much lower phase noise thanks to the high Q value of the optical frequency comb due to the mode locking mechanism. In this paper, we propose and demonstrate a COEO based on a passively mode locked ECDL at 852nm in which the fourth harmonic of the repetition frequency of the ECDL matched exactly the ground state hyperfine splitting frequency of the Cs atoms.

  17. Use of Electronic Resources in a Private University in Nigeria ...

    African Journals Online (AJOL)

    The study examined awareness and constraints in the use of electronic resources by lecturers and students of Ajayi Crowther University, Oyo, Nigeria. It aimed at justifying the resources expended in the provision of electronic resources in terms of awareness, patronage and factors that may be affecting awareness and use ...

  18. Optimization of power output and study of electron beam energy spread in a Free Electron Laser oscillator

    International Nuclear Information System (INIS)

    Abramovich, A.; Pinhasi, Y.; Yahalom, A.; Bar-Lev, D.; Efimov, S.; Gover, A.

    2001-01-01

    Design of a multi-stage depressed collector for efficient operation of a Free Electron Laser (FEL) oscillator requires knowledge of the electron beam energy distribution. This knowledge is necessary to determine the voltages of the depressed collector electrodes that optimize the collection efficiency and overall energy conversion efficiency of the FEL. The energy spread in the electron beam is due to interaction in the wiggler region, as electrons enter the interaction region at different phases relative to the EM wave. This interaction can be simulated well by a three-dimensional simulation code such as FEL3D. The main adjustable parameters that determine the electron beam energy spread after interaction are the e-beam current, the initial beam energy, and the quality factor of the resonator out-coupling coefficient. Using FEL3D, we study the influence of these parameters on the available radiation power and on the electron beam energy distribution at the undulator exit. Simulations performed for I=1.5 A, E=1.4 MeV, L=20% (Internal loss factor) showed that the highest radiated output power and smallest energy spread are attained for an output coupler transmission coefficient T m congruent with 30%

  19. Electronic Resources Management System: Recommendation Report 2017

    KAUST Repository

    Ramli, Rindra M.

    2017-05-01

    This recommendation report provides an overview of the selection process for the new Electronic Resources Management System. The library has decided to move away from Innovative Interfaces Millennium ERM module. The library reviewed 3 system as potential replacements namely: Proquest 360 Resource Manager, Ex Libris Alma and Open Source CORAL ERMS. After comparing and trialling the systems, it was decided to go for Proquest 360 Resource Manager.

  20. use of electronic resources by graduate students of the department

    African Journals Online (AJOL)

    respondent's access electronic resources from the internet via Cybercafé .There is a high ... KEY WORDS: Use, Electronic Resources, Graduate Students, Cybercafé. INTRODUCTION ... Faculty of Education, University of Uyo, Uyo. Olu Olat ...

  1. Anisotropic Friedel oscillations in a two-dimensional electron gas with a Rashba-Dresselhaus spin-orbit interaction

    Science.gov (United States)

    Kozlov, I. V.; Kolesnichenko, Yu. A.

    2017-07-01

    We present a theoretical study of the spatial distribution of the local density of states (LDOS) and the local magnetization density (LMD) in the vicinity of a magnetic point-defect in a degenerate two-dimensional electron gas with a mixed Rashba-Dresselhaus spin-orbit coupling interaction (SOI). The dependence of the Friedel oscillations, which arise under these conditions, on the ratio of the SOI constants is investigated. We obtain asymptotic expressions for the oscillatory parts of the LDOS and the LMD, that are accurate for large distances from the defect. It is shown, that the Friedel oscillations are significantly anisotropic and contain several harmonics for certain ratios of the SOI constants. Period of the oscillations for directions along the symmetry axes of the Fermi contours are determined. Finally, we introduce a method for determining the values of the two SOI constants by measuring the period of the Friedel oscillations of the LDOS and the LMD for different harmonics.

  2. Search for νμ → νe oscillations

    International Nuclear Information System (INIS)

    Godley, A.R.

    1998-01-01

    Full text: Neutrino oscillations, the changing of neutrino flavour state from one of τ, μ or e, to another, are proof of massive neutrinos, in turn pointing to Physics beyond the Standard Model, and so are of great current interest. Solar and atmospheric neutrino results suggested evidence for neutrino oscillations. Further, a tau neutrino mass of ∼ 10 eV could supply the missing mass needed to close the Universe. To satisfy the increasing interest, CERN's Neutrino Physics Program commissioned two concurrent experiments to investigate the possibility of neutrino oscillations, one of which is NOMAD, Neutrino Oscillation Magnetic Detector. NOMAD was designed to verify or deny the earlier positive neutrino oscillations results by searching for muon to tauon neutrino oscillations in accelerator neutrinos. The LSND experiment later provided evidence for muon to electron neutrino oscillations, but due to the multi-purpose design of NOMAD, it was also possible to investigate this channel. Moreover, the area of phase space being uncovered, (related to neutrino energy and oscillation length), overlaps considerably with that of LSND. An electron neutrino oscillation search involves looking for electron neutrinos in what is primarily a muon neutrino beam, with just a small contamination of electron neutrinos. It is surmised that the excess of electron neutrinos come from oscillated muon neutrinos. This type of search is called an appearance search. The principles of such a search will be detailed herein. These include a breakdown of the CERN Neutrino Beam and a method for detecting and collating different neutrino flavours at NOMAD

  3. Microwave oscillator with 'whispering gallery' resonator

    International Nuclear Information System (INIS)

    Kirichenko, A.Ya.; Prokopenko, Yu.V.; Filippov, Yu.F.; Lonin, Yu.F.; Papkovich, V.G.; Ponomarev, A.G.; Prokopenko, Yu.V.; Uvarov, V.T.

    2010-01-01

    It was presented researches of a generation of microwave radiation into system with azimuthally periodical relativistic electron beam current that excites a high-Q quasi-optical dielectric resonator. The Eigen parameters of cylindrical Teflon resonator were determined by numerical computation. Registration of the microwave radiation realizes by a crystal set of 8-mm wavelength range. Research projects of microwave oscillators with high-Q resonators, in which 'whispering gallery' oscillations are excited by an electron flow, are presented. Multiresonator oscillators ideology is based on principles of microwave generation in klystrons with both subcritical and supercritical electron beams currents.

  4. Effects of electron scattering on the oscillations of an X-ray source

    International Nuclear Information System (INIS)

    Kylafis, N.D.; Klimis, G.S.

    1987-01-01

    The time variability observed at infinity due to a variable point source at the center of a spherical cloud of radius R and optical depth to electron scattering tau is analytically determined. The emissin pattern of the source and its time variability are assumed to be of the following three forms: (1) isotropic emission with intensity varying sinusoidally in time with angular frequency Omega(L), (2) emission in the form of a delta-function beam rotating with angular frequency Omega(R) about a fixed axis and with intensity constant in time, and (3) emission in the form of a delta-function beam rotating with angular frequency Omega(R) about a fixed axis and with intensity varying sinusoidally in time with angular frequency Omega(L). More complicated source emissions and variabilities are studied by superposing the above forms. The results of our calculations reveal the conditions under which quasi-periodic oscillations can be observed from X-ray sources, while periodic oscillations are completely smeared out. Furthermore, these results can be used to study the X-ray oscillations of such sources as Her X-1, Cyg X-3, and the Vela pulsar, which are believed to be embedded in scattering clouds. 35 references

  5. Measuring $\\theta_{13}$ via Muon Neutrino to Electron Neutrino Oscillations in the MINOS Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Toner, Ruth B. [Univ. of Cambridge (United Kingdom). Pembroke College

    2011-01-01

    One of the primary goals in neutrino physics at the present moment is to make a measurement of the neutrino oscillation parameter $\\theta_{13}$. This parameter, in addition to being unknown, could potentially allow for the introduction of CP violation into the lepton sector. The MINOS long-baseline neutrino oscillation experiment has the ability to make a measurement of this parameter, by looking for the oscillation of muon neutrinos to electron neutrinos between a Near and Far Detector over a distance of 735 km. This thesis discusses the development of an analysis framework to search for this oscillation mode. Two major improvements to pre-existing analysis techniques have been implemented by the author. First, a novel particle ID technique based on strip topology, known as the Library Event Matching (LEM) method, is optimized for use in MINOS. Second, a multiple bin likelihood method is developed to fit the data. These two improvements, when combined, increase MINOS' sensitivity to $\\sin^2(2\\theta_{13})$ by 27\\% over previous analyses. This thesis sees a small excess over background in the Far Detector. A Frequentist interpretation of the data rules out $\\theta_{13}=0$ at 91\\%. A Bayesian interpretation of the data is also presented, placing the most stringent upper boundary on the oscillation parameter to date, at $\\sin^2(2\\theta_{13})<0.09(0.015)$ for the Normal (Inverted) Hierarchy and $\\delta_{CP}=0$.

  6. Electronic resource management practical perspectives in a new technical services model

    CERN Document Server

    Elguindi, Anne

    2012-01-01

    A significant shift is taking place in libraries, with the purchase of e-resources accounting for the bulk of materials spending. Electronic Resource Management makes the case that technical services workflows need to make a corresponding shift toward e-centric models and highlights the increasing variety of e-formats that are forcing new developments in the field.Six chapters cover key topics, including: technical services models, both past and emerging; staffing and workflow in electronic resource management; implementation and transformation of electronic resource management systems; the ro

  7. Quantum oscillations and the electronic transport properties in multichain nanorings

    International Nuclear Information System (INIS)

    Racolta, D.

    2009-01-01

    We consider a system of multichain nanorings in static electric and magnetic field. The magnetic field induces characteristic phase changes. These phase shifts produce interference phenomena in the case of nanosystems for which the coherence length is larger than the sample dimension. We obtain energy solutions that are dependent on the number of sites N α characterizing a chain, of phase on the phase φ α and on the applied voltage. We found rich oscillations structures exhibited by the magnetic flux and we established the transmission probability. This proceeds by applying Landauer conductance formulae which opens the way to study electronic transport properties. (authors)

  8. Utilization of electronic information resources by academic staff at ...

    African Journals Online (AJOL)

    The study investigated the utilization of Electronic Information resources by the academic staff of Makerere University in Uganda. It examined the academic staff awareness of the resources available, the types of resources provided by the Makerere University Library, the factors affecting resource utilization. The study was ...

  9. Impact of neutrino flavor oscillations on the neutrino-driven wind nucleosynthesis of an electron-capture supernova

    NARCIS (Netherlands)

    Pllumbi, E.; Tamborra, I.; Wanajo, S.; Janka, H.-T.; Hüdepohl, L.

    2015-01-01

    Neutrino oscillations, especially to light sterile states, can affect nucleosynthesis yields because of their possible feedback effect on the electron fraction (Ye). For the first time, we perform nucleosynthesis calculations for neutrino-driven wind trajectories from the neutrino-cooling phase of

  10. Electronic Resources Management Project Presentation 2012

    KAUST Repository

    Ramli, Rindra M.

    2012-01-01

    This presentation describes the electronic resources management project undertaken by the KAUST library. The objectives of this project is to migrate information from MS Sharepoint to Millennium ERM module. One of the advantages of this migration

  11. Theory of Correlated Pairs of Electrons Oscillating in Resonant Quantum States to Reach the Critical Temperature in a Metal

    OpenAIRE

    Aroche, Raúl Riera; Rosas-Cabrera, Rodrigo Arturo; Burgos, Rodrigo Arturo Rosas; Betancourt-Riera, René; Betancourt-Riera, Ricardo

    2017-01-01

    The formation of Correlated Electron Pairs Oscillating around the Fermi level in Resonant Quantum States (CEPO-RQS), when a metal is cooled to its critical temperature T=Tc, is studied. The necessary conditions for the existence of CEPO-RQS are analyzed. The participation of electron-electron interaction screened by an electron dielectric constant of the form proposed by Thomas Fermi is considered and a physical meaning for the electron-phonon-electron interaction in the formation of the CEPO...

  12. Electron plasma oscillations at arbitrary Debye lengths

    International Nuclear Information System (INIS)

    Lehnert, B.

    1990-12-01

    A solution is presented for electron plasma oscillation in a thermalized homogeneous plasma, at arbitrary ratios between the Debye length λ D and the perturbation wave length λ. The limit λ D D >> λ corresponds to the free-streaming limit of strong kinetic phase-mixing due to large particle excursions. A strong large Debye distance (LDD) effect already appears when λ D > approx λ. The initial amplitude of the fluid-like contribution to the macroscopic density perturbation then becomes small as compared to the contribution from the free-streaming part. As a consequence, only a small fraction of the density perturbation remains after a limited number of kinetic damping times of the free-streaming part. The analysis further shows that a representation in terms of normal model of the form exp(-iωt) leads to amplitude factors of these modes which are related to each other and which depend on the combined free-streaming and fluid behaviour of the plasma. Consequently, these modes are coupled and cannot be treated as being independent of each other. (au)

  13. Subharmonic buncher for the Los Alamos free-electron laser oscillator experiment

    International Nuclear Information System (INIS)

    Fraser, J.S.

    1983-01-01

    A high efficiency free-electron laser oscillator experiment is being constructed at Los Alamos National Laboratory. A buncher system has been designed to deliver 30-ps, 5-nC electron bunches to a 20-MeV standing-wave linac at the 60th subharmonic of the 1300-MHz accelerator frequency. The first 108.3-MHz buncher cavity accepts a 5-ns, 5-A peak current pulse from a triode gun. Following a 120-cm drift space, a second 108.3-MHz cavity is used, primarily to enhance the bunching of the trailing half of the bunch. A 1300-MHz cavity with 20-cm drift spaces at the each end completes the beamline components. The bunching process continues into the linac's first three accelerating cells. Two thin iron-shielded lenses and several large-diameter solenoids provide axial magnetic fields for radial focusing

  14. A search for muon neutrino to electron neutrino oscillations in the MINOS Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Ochoa Ricoux, Juan Pedro [California Inst. of Technology (CalTech), Pasadena, CA (United States)

    2009-01-01

    We perform a search for vμ → ve oscillations, a process which would manifest a nonzero value of the θ13 mixing angle, in the MINOS long-baseline neutrino oscillation experiment. The analysis consists of searching for an excess of ve charged-current candidate events over the predicted backgrounds, made mostly of neutral-current events with high electromagnetic content. A novel technique to select electron neutrino events is developed, which achieves an improved separation between the signal and the backgrounds, and which consequently yields a better reach in θ13. The backgrounds are predicted in the Far Detector from Near Detector measurements. An excess is observed in the Far Detector data over the predicted backgrounds, which is consistent with the background-only hypothesis at 1.2 standard deviations.

  15. Practical guide to electronic resources in the humanities

    CERN Document Server

    Dubnjakovic, Ana

    2010-01-01

    From full-text article databases to digitized collections of primary source materials, newly emerging electronic resources have radically impacted how research in the humanities is conducted and discovered. This book, covering high-quality, up-to-date electronic resources for the humanities, is an easy-to-use annotated guide for the librarian, student, and scholar alike. It covers online databases, indexes, archives, and many other critical tools in key humanities disciplines including philosophy, religion, languages and literature, and performing and visual arts. Succinct overviews of key eme

  16. Utilisation of Electronic Information Resources By Lecturers in ...

    African Journals Online (AJOL)

    This study assesses the use of information resources, specifically, electronic databases by lecturers/teachers in Universities and Colleges of Education in South Western Nigeria. Information resources are central to teachers' education. It provides lecturers/teachers access to information that enhances research and ...

  17. Simulation studies of plasma waves in the electron foreshock: The generation of downshifted oscillations

    International Nuclear Information System (INIS)

    Dum, C.T.

    1990-01-01

    The generation of waves with frequencies downshifted from the plasma frequency, as observed in the electron foreshock, is analyzed by particle simulation. Wave excitation differs fundamentally from the familiar excitation of the plasma eigenmodes by a gentle bump-on-tail electron distribution. Beam modes are destabilized by resonant interaction with bulk electrons, provided the beamvelocity spread is very small. These modes are stabilized, starting with the higher frequencies, as the beam is broadened and slowed down by the interaction with the wave spectrum. Initially, a very cold beam is also capable of exciting frequencies considerably above the plasma frequency, but such oscillations are quickly stabilized. Low-frequency modes persist for a long time, until the bump in the electron distribution is completely ironed out. This diffusion process also is quite different from the familiar case of well-separated beam and bulk electrons. A quantitative analysis of these processes is carried out

  18. Discipline, availability of electronic resources and the use of Finnish National Electronic Library - FinELib

    Directory of Open Access Journals (Sweden)

    Sanna Torma

    2004-01-01

    Full Text Available This study elaborated relations between digital library use by university faculty, users' discipline and the availability of key resources in the Finnish National Electronic Library (FinELib, Finnish national digital library, by using nationwide representative survey data. The results show that the perceived availability of key electronic resources by researchers in FinELib was a stronger predictor of the frequency and purpose of use of its services than users' discipline. Regardless of discipline a good perceived provision of central resources led to a more frequent use of FinELib. The satisfaction with the services did not vary with the discipline, but with the perceived availability of resources.

  19. The Role of the Acquisitions Librarian in Electronic Resources Management

    Science.gov (United States)

    Pomerantz, Sarah B.

    2010-01-01

    With the ongoing shift to electronic formats for library resources, acquisitions librarians, like the rest of the profession, must adapt to the rapidly changing landscape of electronic resources by keeping up with trends and mastering new skills related to digital publishing, technology, and licensing. The author sought to know what roles…

  20. Investigation of a free electron laser oscillator in the X-ray wavelength regime for the European XFEL

    International Nuclear Information System (INIS)

    Zemella, Johann Christian Uwe

    2013-09-01

    In this thesis an X-ray free electron laser oscillator for the European XFEL is described. Such an oscillator consists of at least two Bragg deflecting crystals, in this content two or four Diamond crystals, focussing mirrors and an undulator. The advantage of Diamond is caused by the high reflectivity and the high thermal conductivity, which is necessary for dissipate the absorbed energy out of the center of the crystal. In context of this thesis the principle layout of an XFELO for the European XFEL and the FEL process is presented. Effects on the FEL process due to the disturbances of the electron beam or the XFELO cavity are discussed. As second aspect the thermal evolution in the crystal under absorbed XFELO-pulses is investigated. An experiment for the investigation of the thermal evolution of crystals under simulated XFELO conditions is presented.

  1. Formation of low time-bandwidth product, single-sided exponential optical pulses in free-electron laser oscillators

    NARCIS (Netherlands)

    MacLeod, A. M.; Yan, X.; Gillespie, W. A.; Knippels, G.M.H.; Oepts, D.; van der Meer, A. F. G.; Rella, C. W.; Smith, T. J.; Schwettman, H. A.

    2000-01-01

    The detailed shape of picosecond optical pulses from a free-electron laser (FEL) oscillator has been studied for various cavity detunings. For large values of the cavity detuning the optical pulse develops an exponential leading edge, with a time constant proportional to the applied cavity detuning

  2. Analysis of Pedagogic Potential of Electronic Educational Resources with Elements of Autodidactics

    Directory of Open Access Journals (Sweden)

    Igor A.

    2018-03-01

    Full Text Available Introduction: in recent years didactic properties of electronic educational resources undergo considerable changes, nevertheless, the question of studying of such complete phenomenon as “an electronic educational resource with autodidactics elements” remains open, despite sufficient scientific base of researches of the terms making this concept. Article purpose – determination of essence of electronic educational resources with autodidactics elements. Materials and Methods: the main method of research was the theoretical analysis of the pedagogical and psychological literature on the problem under study. We used the theoretical (analysis, synthesis, comparison and generalization methods, the method of interpretation, pedagogical modeling, and empirical methods (observation, testing, conversation, interview, analysis of students’ performance, pedagogical experiment, peer review. Results: we detected the advantages of electronic educational resources in comparison with traditional ones. The concept of autodidactics as applied to the subject of research is considered. Properties of electronic educational resources with a linear and nonlinear principle of construction are studied.The influence of the principle of construction on the development of the learners’ qualities is shown. We formulated an integral definition of electronic educational resources with elements of autodidactics, namely, the variability, adaptivity and cyclicity of training. A model of the teaching-learning process with electronic educational resources is developed. Discussion and Conclusions: further development of a problem will allow to define whether electronic educational resources with autodidactics elements pedagogical potential for realization of educational and self-educational activity of teachers have, to modify technological procedures taking into account age features of students, their specialties and features of the organization of process of training of

  3. Preservation and conservation of electronic information resources of ...

    African Journals Online (AJOL)

    The major holdings of the broadcast libraries of the Nigerian Television Authority (NTA) are electronic information resources; therefore, providing safe places for general management of these resources have aroused interest in the industry in Nigeria for sometimes. The need to study the preservation and conservation of ...

  4. Building an electronic resource collection a practical guide

    CERN Document Server

    Lee, Stuart D

    2004-01-01

    This practical book guides information professionals step-by-step through building and managing an electronic resource collection. It outlines the range of electronic products currently available in abstracting and indexing, bibliographic, and other services and then describes how to effectively select, evaluate and purchase them.

  5. Analysis of Human Resources Management Strategy in China Electronic Commerce Enterprises

    Science.gov (United States)

    Shao, Fang

    The paper discussed electronic-commerce's influence on enterprise human resources management, proposed and proved the human resources management strategy which electronic commerce enterprise should adopt from recruitment strategy to training strategy, keeping talent strategy and other ways.

  6. Impact of Neutrino Flavor Oscillations on the Neutrino-driven Wind Nucleosynthesis of an Electron-capture Supernova

    Science.gov (United States)

    Pllumbi, Else; Tamborra, Irene; Wanajo, Shinya; Janka, Hans-Thomas; Hüdepohl, Lorenz

    2015-08-01

    Neutrino oscillations, especially to light sterile states, can affect nucleosynthesis yields because of their possible feedback effect on the electron fraction (Ye). For the first time, we perform nucleosynthesis calculations for neutrino-driven wind trajectories from the neutrino-cooling phase of an 8.8 {M}⊙ electron-capture supernova (SN), whose hydrodynamic evolution was computed in spherical symmetry with sophisticated neutrino transport and whose Ye evolution was post-processed by including neutrino oscillations between both active and active-sterile flavors. We also take into account the α-effect as well as weak magnetism and recoil corrections in the neutrino absorption and emission processes. We observe effects on the Ye evolution that depend in a subtle way on the relative radial positions of the sterile Mikheyev-Smirnov-Wolfenstein resonances, on collective flavor transformations, and on the formation of α particles. For the adopted SN progenitor, we find that neutrino oscillations, also to a sterile state with eV mass, do not significantly affect the element formation and in particular cannot make the post-explosion wind outflow neutron-rich enough to activate a strong r-process. Our conclusions become even more robust when, in order to mimic equation-of-state-dependent corrections due to nucleon potential effects in the dense-medium neutrino opacities, six cases with reduced Ye in the wind are considered. In these cases, despite the conversion of active neutrinos to sterile neutrinos, Ye increases or is not significantly lowered compared to the values obtained without oscillations and active flavor transformations. This is a consequence of a complicated interplay between sterile-neutrino production, neutrino-neutrino interactions, and α-effect.

  7. Rabi oscillation and electron-spin-echo envelope modulation of the photoexcited triplet spin system in silicon

    Science.gov (United States)

    Akhtar, Waseem; Sekiguchi, Takeharu; Itahashi, Tatsumasa; Filidou, Vasileia; Morton, John J. L.; Vlasenko, Leonid; Itoh, Kohei M.

    2012-09-01

    We report on a pulsed electron paramagnetic resonance (EPR) study of the photoexcited triplet state (S=1) of oxygen-vacancy centers in silicon. Rabi oscillations between the triplet sublevels are observed using coherent manipulation with a resonant microwave pulse. The Hahn echo and stimulated echo decay profiles are superimposed with strong modulations known as electron-spin-echo envelope modulation (ESEEM). The ESEEM spectra reveal a weak but anisotropic hyperfine coupling between the triplet electron spin and a 29Si nuclear spin (I=1/2) residing at a nearby lattice site, that cannot be resolved in conventional field-swept EPR spectra.

  8. Using XML Technologies to Organize Electronic Reference Resources

    OpenAIRE

    Huser, Vojtech; Del Fiol, Guilherme; Rocha, Roberto A.

    2005-01-01

    Provision of access to reference electronic resources to clinicians is becoming increasingly important. We have created a framework for librarians to manage access to these resources at an enterprise level, rather than at the individual hospital libraries. We describe initial project requirements, implementation details, and some preliminary results.

  9. Simulation studies of plasma waves in the electron foreshock - The generation of downshifted oscillations

    Science.gov (United States)

    Dum, C. T.

    1990-01-01

    The generation of waves with frequencies downshifted from the plasma frequency, as observed in the electron foreshock, is analyzed by particle simulation. Wave excitation differs fundamentally from the familiar excitation of the plasma eigenmodes by a gentle bump-on-tail electron distribution. Beam modes are destabilized by resonant interaction with bulk electrons, provided the beam velocity spread is very small. These modes are stabilized, starting with the higher frequencies, as the beam is broadened and slowed down by the interaction with the wave spectrum. Initially a very cold beam is also capable of exciting frequencies considerably above the plasma frequency, but such oscillations are quickly stabilized. Low-frequency modes persist for a long time, until the bump in the electron distribution is completely 'ironed' out. This diffusion process also is quite different from the familiar case of well-separated beam and bulk electrons. A quantitative analysis of these processes is carried out.

  10. Electronic Resources and Mission Creep: Reorganizing the Library for the Twenty-First Century

    Science.gov (United States)

    Stachokas, George

    2009-01-01

    The position of electronic resources librarian was created to serve as a specialist in the negotiation of license agreements for electronic resources, but mission creep has added more functions to the routine work of electronic resources such as cataloging, gathering information for collection development, and technical support. As electronic…

  11. Synchronization of hyperchaotic oscillators

    DEFF Research Database (Denmark)

    Tamasevicius, A.; Cenys, A.; Mykolaitis, G.

    1997-01-01

    Synchronization of chaotic oscillators is believed to have promising applications in secure communications. Hyperchaotic systems with multiple positive Lyapunov exponents (LEs) have an advantage over common chaotic systems with only one positive LE. Three different types of hyperchaotic electronic...... oscillators are investigated demonstrating synchronization by means of only one properly selected variable....

  12. A theory of generalized Bloch oscillations

    DEFF Research Database (Denmark)

    Duggen, Lars; Lew Yan Voon, L. C.; Lassen, Benny

    2016-01-01

    Bloch oscillations of electrons are shown to occur for cases when the energy spectrum does not consist of the traditional evenly-spaced ladders and the potential gradient does not result from an external electric field. A theory of such generalized Bloch oscillations is presented and an exact...... oscillations. We stipulate that the presented theory of generalized Bloch oscillations can be extended to other systems such as acoustics and photonics....

  13. Neutrino oscillations in the early universe

    International Nuclear Information System (INIS)

    Enqvist, K.

    1990-01-01

    The oscillations of electron neutrinos into inert neutrinos may have resonant behaviour in the heat bath of the early Universe. It is shown that any initial neutrino asymmetry will be washed away by the oscillations. Neutrino oscillations would affect also primordial helium production, which implies stringent limits on the neutrino mixing parameters. (orig.)

  14. Magnetically insulated transmission line oscillator

    Science.gov (United States)

    Bacon, L.D.; Ballard, W.P.; Clark, M.C.; Marder, B.M.

    1987-05-19

    A magnetically insulated transmission line oscillator employs self-generated magnetic fields to generate microwave energy. An anode of the oscillator includes slow-wave structures which are formed of a plurality of thin conductive vanes defining cavities therebetween, and a gap is formed between the anode and a cathode of the oscillator. In response to a pulsed voltage applied to the anode and cathode, self-generated magnetic fields are produced in a cross-field orientation with respect to the orientation of the electric field between the anode and the cathode. The cross-field magnetic fields insulate the flow of electrons in the gap and confine the flow of electrons within the gap. 11 figs.

  15. Hall field-induced magnetoresistance oscillations of a two-dimensional electron system

    International Nuclear Information System (INIS)

    Kunold, A.; Torres, M.

    2008-01-01

    We develop a model of the nonlinear response to a dc electrical current of a two-dimensional electron system (2DES) placed on a magnetic field. Based on the exact solution to the Schroedinger equation in arbitrarily strong electric and magnetic fields, and separating the relative and guiding center coordinates, a Kubo-like formula for the current is worked out as a response to the impurity scattering. Self-consistent expressions determine the longitudinal and Hall components of the electric field in terms of the dc current. The differential resistivity displays strong Hall field-induced oscillations, in agreement with the main features of the phenomenon observed in recent experiments

  16. Assessment of oscillator strengths with multiconfigurational short-range density functional theory for electronic excitations in organic molecules

    DEFF Research Database (Denmark)

    Hedegård, Erik Donovan

    2017-01-01

    considered the large collection of organic molecules whose excited states were investigated with a range of electronic structure methods by Thiel et al. As a by-product of our calculations of oscillator strengths, we also obtain electronic excitation energies, which enable us to compare the performance......We have in a series of recent papers investigated electronic excited states with a hybrid between a complete active space self-consistent field (CASSCF) wave function and density functional theory (DFT). This method has been dubbed the CAS short-range DFT method (CAS–srDFT). The previous papers...

  17. Simulation Studies of the X-Ray Free-Electron Laser Oscillator

    International Nuclear Information System (INIS)

    Lindberg, R.R.; Shyd'ko, Y.; Kim, K.-J; Fawley, W.M.

    2009-01-01

    Simulations of the x-ray free-electron laser (FEL) oscillator are presented that include transverse effects and realistic Bragg crystal properties with the two-dimensional code GINGER. In the present cases considered the radiation divergence is much narrower than the crystal acceptance, and the numerical algorithm can be simplified by ignoring the finite angular bandwidth of the crystal. In this regime GINGER shows that the saturated x-ray pulses have 109 photons and are nearly Fourier-limited with peak powers in excess of 1 MW. Wealso include preliminary results for a four-mirror cavity that can be tuned in wavelength over a few percent, with future plans to incorporate the full transverse response of the Bragg crystals into GINGER to more accurately model this tunable source.

  18. Experimental demonstration of revival of oscillations from death in coupled nonlinear oscillators

    Energy Technology Data Exchange (ETDEWEB)

    Senthilkumar, D. V., E-mail: skumarusnld@gmail.com [School of Physics, Indian Institute of Science Education and Research, Thiruvananthapuram 695016 (India); Centre for Nonlinear Science and Engineering, School of Electrical and Electronics Engineering, SASTRA University, Thanjavur 613 401 (India); Suresh, K. [Department of Physics, Anjalai Ammal-Engineering College, Kovilvenni 614 403, Tamilnadu (India); Centre for Nonlinear Dynamics, Bharathidasan University, Trichy 620024, Tamilnadu (India); Chandrasekar, V. K. [Centre for Nonlinear Science and Engineering, School of Electrical and Electronics Engineering, SASTRA University, Thanjavur 613 401 (India); Zou, Wei [School of Mathematics and Statistics, Huazhong University of Science and Technology, Wuhan 430074 (China); Centre for Mathematical Sciences, Huazhong University of Science and Technology, Wuhan 430074 (China); Dana, Syamal K. [CSIR-Indian Institute of Chemical Biology, Kolkata 700032 (India); Kathamuthu, Thamilmaran [Centre for Nonlinear Dynamics, Bharathidasan University, Trichy 620024, Tamilnadu (India); Kurths, Jürgen [Potsdam Institute for Climate Impact Research, Telegrafenberg, Potsdam D-14415 (Germany); Institute of Physics, Humboldt University Berlin, Berlin D-12489 (Germany); Institute for Complex Systems and Mathematical Biology, University of Aberdeen, Aberdeen AB24 3FX (United Kingdom); Department of Control Theory, Nizhny Novgorod State University, Gagarin Avenue 23, 606950 Nizhny Novgorod (Russian Federation)

    2016-04-15

    We experimentally demonstrate that a processing delay, a finite response time, in the coupling can revoke the stability of the stable steady states, thereby facilitating the revival of oscillations in the same parameter space where the coupled oscillators suffered the quenching of oscillation. This phenomenon of reviving of oscillations is demonstrated using two different prototype electronic circuits. Further, the analytical critical curves corroborate that the spread of the parameter space with stable steady state is diminished continuously by increasing the processing delay. Finally, the death state is completely wiped off above a threshold value by switching the stability of the stable steady state to retrieve sustained oscillations in the same parameter space. The underlying dynamical mechanism responsible for the decrease in the spread of the stable steady states and the eventual reviving of oscillation as a function of the processing delay is explained using analytical results.

  19. Rabi oscillation between states of a coupled harmonic oscillator

    International Nuclear Information System (INIS)

    Park, Tae Jun

    2003-01-01

    Rabi oscillation between bound states of a single potential is well known. However the corresponding formula between the states of two different potentials has not been obtained yet. In this work, we derive Rabi formula between the states of a coupled harmonic oscillator which may be used as a simple model for the electron transfer. The expression is similar to typical Rabi formula for a single potential. This result may be used to describe transitions between coupled diabatic potential curves

  20. Spatial distribution of electron plasma oscillations in the Earth`s foreshock at ISEE 3

    Energy Technology Data Exchange (ETDEWEB)

    Greenstadt, E.W.; Moses, S.L.; Coroniti, F.V. [TRW, Redondo Beach, CA (United States)] [and others

    1995-10-01

    Electric field oscillations recorded by the 10-56 kHz channels of TRW`s plasma wave detector during parts of two of the ISEE 3 circumterrestrial orbits in 1983 have been used to make the first mapping of Earth`s electron plasma wave foreshock. By combining data from the two trajectory segments, each of which provided relatively meager spatial sampling outside the bow shock, but high variation of interplanetary magnetic field (IMF) direction, a first-order pattern of occurrence of electron plasma waves, hence also backstreaming electrons, has been determined. The authors depict the pattern with an adaptation of the mapping program previously used for the Venus electron foreshock. As at Venus, plasma wave activity was concentrated most densely along the IMF line tangent to the bow shock. Their mappings with three additional ISEE 3 channels surrounding the local electron plasma frequency indicate a richer distribution of waves in the foreshock than the single electron frequency channel of Pioneer Venus Orbiter could detect around Venus. 14 refs., 4 figs.

  1. A theory of generalized Bloch oscillations

    International Nuclear Information System (INIS)

    Duggen, Lars; Lassen, Benny; Lew Yan Voon, L C; Willatzen, Morten

    2016-01-01

    Bloch oscillations of electrons are shown to occur for cases when the energy spectrum does not consist of the traditional evenly-spaced ladders and the potential gradient does not result from an external electric field. A theory of such generalized Bloch oscillations is presented and an exact calculation is given to confirm this phenomenon. Our results allow for a greater freedom of design for experimentally observing Bloch oscillations. For strongly coupled oscillator systems displaying Bloch oscillations, it is further demonstrated that reordering of oscillators leads to destruction of Bloch oscillations. We stipulate that the presented theory of generalized Bloch oscillations can be extended to other systems such as acoustics and photonics. (paper)

  2. Electronic Resources Management System: Recommendation Report 2017

    KAUST Repository

    Ramli, Rindra M.

    2017-01-01

    This recommendation report provides an overview of the selection process for the new Electronic Resources Management System. The library has decided to move away from Innovative Interfaces Millennium ERM module. The library reviewed 3 system

  3. Nonstationary oscillation of gyrotron backward wave oscillators with cylindrical interaction structure

    International Nuclear Information System (INIS)

    Chen, Shih-Hung; Chen, Liu

    2013-01-01

    The nonstationary oscillation of the gyrotron backward wave oscillator (gyro-BWO) with cylindrical interaction structure was studied utilizing both steady-state analyses and time-dependent simulations. Comparisons of the numerical results reveal that the gyro-BWO becomes nonstationary when the trailing field structure completely forms due to the dephasing energetic electrons. The backward propagation of radiated waves with a lower resonant frequency from the trailing field structure interferes with the main internal feedback loop, thereby inducing the nonstationary oscillation of the gyro-BWO. The nonstationary gyro-BWO exhibits the same spectral pattern of modulated oscillations with a constant frequency separation between the central frequency and sidebands throughout the whole system. The frequency separation is found to be scaled with the square root of the maximum field amplitude, thus further demonstrating that the nonstationary oscillation of the gyro-BWO is associated with the beam-wave resonance detuning

  4. Microwave-Induced Magneto-Oscillations and Signatures of Zero-Resistance States in Phonon-Drag Voltage in Two-Dimensional Electron Systems.

    Science.gov (United States)

    Levin, A D; Momtaz, Z S; Gusev, G M; Raichev, O E; Bakarov, A K

    2015-11-13

    We observe the phonon-drag voltage oscillations correlating with the resistance oscillations under microwave irradiation in a two-dimensional electron gas in perpendicular magnetic field. This phenomenon is explained by the influence of dissipative resistivity modified by microwaves on the phonon-drag voltage perpendicular to the phonon flux. When the lowest-order resistance minima evolve into zero-resistance states, the phonon-drag voltage demonstrates sharp features suggesting that current domains associated with these states can exist in the absence of external dc driving.

  5. Phase inversion and frequency doubling of reflection high-energy electron diffraction intensity oscillations in the layer-by-layer growth of complex oxides

    Science.gov (United States)

    Mao, Zhangwen; Guo, Wei; Ji, Dianxiang; Zhang, Tianwei; Gu, Chenyi; Tang, Chao; Gu, Zhengbin; Nie*, Yuefeng; Pan, Xiaoqing

    In situ reflection high-energy electron diffraction (RHEED) and its intensity oscillations are extremely important for the growth of epitaxial thin films with atomic precision. The RHEED intensity oscillations of complex oxides are, however, rather complicated and a general model is still lacking. Here, we report the unusual phase inversion and frequency doubling of RHEED intensity oscillations observed in the layer-by-layer growth of SrTiO3 using oxide molecular beam epitaxy. In contacts to the common understanding that the maximum(minimum) intensity occurs at SrO(TiO2) termination, respectively, we found that both maximum or minimum intensities can occur at SrO, TiO2, or even incomplete terminations depending on the incident angle of the electron beam, which raises a fundamental question if one can rely on the RHEED intensity oscillations to precisely control the growth of thin films. A general model including surface roughness and termination dependent mean inner potential qualitatively explains the observed phenomena, and provides the answer to the question how to prepare atomically and chemically precise surface/interfaces using RHEED oscillations for complex oxides. We thank National Basic Research Program of China (No. 11574135, 2015CB654901) and the National Thousand-Young-Talents Program.

  6. Suppression and revival of oscillation in indirectly coupled limit cycle oscillators

    International Nuclear Information System (INIS)

    Sharma, P.R.; Kamal, N.K.; Verma, U.K.; Suresh, K.; Thamilmaran, K.; Shrimali, M.D.

    2016-01-01

    Highlights: • The phenomena of suppression and revival of oscillations are studied in indirectly coupled nonlinear oscillators. • The decay parameter and a feedback factor play a crucial role in emergent dynamical behavior of oscillators. • The critical curves for different dynamical regions are obtained analytically using linear stability analysis. • Electronic circuit experiments demonstrate these emergent dynamical states. - Abstract: We study the phenomena of suppression and revival of oscillations in a system of limit cycle oscillators coupled indirectly via a dynamic local environment. The dynamics of the environment is assumed to decay exponentially with time. We show that for appropriate coupling strength, the decay parameter of the environment plays a crucial role in the emergent dynamics such as amplitude death (AD) and oscillation death (OD). We also show that introducing a feedback factor in the diffusion term revives the oscillations in this system. The critical curves for the regions of different emergent states as a function of coupling strength, decay parameter of the environment and feedback factor in the coupling are obtained analytically using linear stability analysis. These results are found to be consistent with the numerics and are also observed experimentally.

  7. The Internet School of Medicine: use of electronic resources by medical trainees and the reliability of those resources.

    Science.gov (United States)

    Egle, Jonathan P; Smeenge, David M; Kassem, Kamal M; Mittal, Vijay K

    2015-01-01

    Electronic sources of medical information are plentiful, and numerous studies have demonstrated the use of the Internet by patients and the variable reliability of these sources. Studies have investigated neither the use of web-based resources by residents, nor the reliability of the information available on these websites. A web-based survey was distributed to surgical residents in Michigan and third- and fourth-year medical students at an American allopathic and osteopathic medical school and a Caribbean allopathic school regarding their preferred sources of medical information in various situations. A set of 254 queries simulating those faced by medical trainees on rounds, on a written examination, or during patient care was developed. The top 5 electronic resources cited by the trainees were evaluated for their ability to answer these questions accurately, using standard textbooks as the point of reference. The respondents reported a wide variety of overall preferred resources. Most of the 73 responding medical trainees favored textbooks or board review books for prolonged studying, but electronic resources are frequently used for quick studying, clinical decision-making questions, and medication queries. The most commonly used electronic resources were UpToDate, Google, Medscape, Wikipedia, and Epocrates. UpToDate and Epocrates had the highest percentage of correct answers (47%) and Wikipedia had the lowest (26%). Epocrates also had the highest percentage of wrong answers (30%), whereas Google had the lowest percentage (18%). All resources had a significant number of questions that they were unable to answer. Though hardcopy books have not been completely replaced by electronic resources, more than half of medical students and nearly half of residents prefer web-based sources of information. For quick questions and studying, both groups prefer Internet sources. However, the most commonly used electronic resources fail to answer clinical queries more than half

  8. Solid state Ka-band pulse oscillator with frequency electronic switching

    Directory of Open Access Journals (Sweden)

    Dvornichenko V. P.

    2015-08-01

    Full Text Available Transmitting devices for small radars in the millimeter wavelength range with high resolution on range and noise immunity. The work presents the results of research and development of compact pulse oscillators with digital frequency switching from pulse to pulse. The oscillator consists of a frequency synthesizer and a synchronized amplifier on the IMPATT diode. Reference oscillator of synthesizer is synchronized by crystal oscillator with digital PLL system and contains a frequency multiplier and an amplifier operating in pulse mode. Small-sized frequency synthesizer of 8 mm wave lengths provides an output power of ~1.2 W per pulse with a frequency stability of no worse than 2•10–6. Radiation frequency is controlled by three-digit binary code in OOL levels. Synchronized amplifier made on IMPATT diodes provides microwave power up to 20 W in oscillator output with microwave pulse duration of 100—300 ns in an operating band. The oscillator can be used as a driving source for the synchronization of semiconductor and electro-vacuum devices of pulsed mode, and also as a transmitting device for small-sized radar of millimeter wave range.

  9. Influence of flavor oscillations on neutrino beam instabilities

    Energy Technology Data Exchange (ETDEWEB)

    Mendonça, J. T., E-mail: titomend@ist.utl.pt [Instituto de Física, Universidade de São Paulo, 05508-090 São Paulo SP (Brazil); Haas, F. [Instituto de Física, Universidade Federal do Rio Grande do Sul, 91501-970 Porto Alegre RS (Brazil); Bret, A. [ETSI Industriales, Universidad de Castilla-La Mancha, 13071 Ciudad Real, Spain and Instituto de Investigaciones Energeticas y Aplicaciones Industriales, Campus Universitario de Ciudad Real, 13071 Ciudad Real (Spain)

    2014-09-15

    We consider the collective neutrino plasma interactions and study the electron plasma instabilities produced by a nearly mono-energetic neutrino beam in a plasma. We describe the mutual interaction between neutrino flavor oscillations and electron plasma waves. We show that the neutrino flavor oscillations are not only perturbed by electron plasmas waves but also contribute to the dispersion relation and the growth rates of neutrino beam instabilities.

  10. Analysis of parasitic oscillations in 42 GHz gyrotron beam tunnel

    Science.gov (United States)

    Kumar, N.; Singh, U.; Singh, T. P.; Sinha, A. K.

    2011-02-01

    Parasitic oscillation excitation analysis has been carried out for the 42 GHz gyrotron beam tunnel. This article presents a systematic approach for the analysis of parasitic oscillation excitation. The electron trajectory code EGUN has been used for the estimation of the electron beam parameters in the beam tunnel. The electromagnetic simulation code CST-MS has been used for the eigenmode and Q value analysis. The analysis of the parasitic oscillations has been performed for the symmetric TE modes and the first three cavity side copper rings. Four different approaches- the Q value study, the mode maxima-electron beam radius mismatching, the electron cyclotron frequency-mode excitation frequency mismatching and the backward wave interaction analysis- have been used for the parasitic oscillation analysis.

  11. ANALYTICAL REVIEW OF ELECTRONIC RESOURCES FOR THE STUDY OF LATIN

    Directory of Open Access Journals (Sweden)

    Olena Yu. Balalaieva

    2014-04-01

    Full Text Available The article investigates the current state of development of e-learning content in the Latin language. It is noted that the introduction of ICT in the educational space has expanded the possibility of studying Latin, opened access to digital libraries resources, made it possible to use scientific and educational potential and teaching Latin best practices of world's leading universities. A review of foreign and Ukrainian information resources and electronic editions for the study of Latin is given. Much attention was paid to the didactic potential of local and online multimedia courses of Latin, electronic textbooks, workbooks of interactive tests and exercises, various dictionaries and software translators, databases and digital libraries. Based on analysis of the world market of educational services and products the main trends in the development of information resources and electronic books are examined. It was found that multimedia courses with interactive exercises or workbooks with interactive tests, online dictionaries and translators are the most widely represented and demanded. The noticeable lagging of Ukrainian education and computer linguistics in quantitative and qualitative measures in this industry is established. The obvious drawback of existing Ukrainian resources and electronic editions for the study of Latin is their noninteractive nature. The prospects of e-learning content in Latin in Ukraine are outlined.

  12. Elektronik Bilgi Kaynaklarının Seçimi / Selection of Electronic Information Resources

    Directory of Open Access Journals (Sweden)

    Pınar Al

    2003-04-01

    Full Text Available For many years, library users have used only from the printed media in order to get the information that they have needed. Today with the widespread use of the Web and the addition of electronic information resources to library collections, the use of information in the electronic environment as well as in printed media is started to be used. In time, such types of information resources as, electronic journals, electronic books, electronic encyclopedias, electronic dictionaries and electronic theses have been added to library collections. In this study, selection criteria that can be used for electronic information resources are discussed and suggestions are provided for libraries that try to select electronic information resources for their collections.

  13. Neutrino oscillations and antiνsub(e)-e scattering

    International Nuclear Information System (INIS)

    Halls, B.; McKellar, B.H.J.

    1980-01-01

    Electron antineutrino-electron scattering is modified in the presence of neutrino mixing and neutrino oscillation. In the Weinberg-Salam model the results for reactor antineutrinos are insensitive to the degree of mixing, to the extent that the experiment of Reines, Gurr and Sobel cannot differentiate between no oscillation and complete disappearance of the electron antineutrinos from the beam

  14. Power system stabilizers based on distributed energy resources for damping of inter-area oscillations

    Directory of Open Access Journals (Sweden)

    Stefanov Predrag Č.

    2014-01-01

    Full Text Available This paper deals with inter-area power oscillations damping enhancement by distributed energy resources contained in typical micro grid. Main idea behind this work is to use distributed generation and distributed storage, such as battery energy storage to mimic conventional power system stabilizer, but with regulating active power output, rather than reactive power, as in standard power system stabilizer realization. The analysis of the small signal stability is established for four-machine, two-area system, with inverter based micro grids in each area. Dynamic simulation results are included in this work and they show that proposed controller provides additional damping effect to this test system.

  15. Access to electronic resources by visually impaired people

    Directory of Open Access Journals (Sweden)

    Jenny Craven

    2003-01-01

    Full Text Available Research into access to electronic resources by visually impaired people undertaken by the Centre for Research in Library and Information Management has not only explored the accessibility of websites and levels of awareness in providing websites that adhere to design for all principles, but has sought to enhance understanding of information seeking behaviour of blind and visually impaired people when using digital resources.

  16. Ion Acoustic Waves in the Presence of Langmuir Oscillations

    DEFF Research Database (Denmark)

    Pécseli, Hans

    1976-01-01

    The dielectric function for long-wavelength, low-frequency ion acoustic waves in the presence of short-wavelength, high-frequency electron oscillations is presented, where the ions are described by the collision-free Vlasov equation. The effect of the electron oscillations can be appropriately...

  17. Oscillators - an approach for a better understanding

    DEFF Research Database (Denmark)

    Lindberg, Erik

    2003-01-01

    The aim of this tutorial is to provide an electronic engineer knowledge and insight for a better understanding of the mechanisms behind the behaviour of electronic oscillators. A linear oscillator is a mathematical fiction which can only be used as a starting point for the design of a real...... oscillator based on the Barkhausen criteria. Statements in textbooks and papers saying that the nonlinearities are bringing back the poles to the imaginary axis are wrong. The concept of "frozen eigenvalues" is introduced by means of piece-wise-linear modelling of the nonlinear components which are necessary...

  18. Library training to promote electronic resource usage

    DEFF Research Database (Denmark)

    Frandsen, Tove Faber; Tibyampansha, Dativa; Ibrahim, Glory

    2017-01-01

    Purpose: Increasing the usage of electronic resources is an issue of concern for many libraries all over the world. Several studies stress the importance of information literacy and instruction in order to increase the usage. Design/methodology/approach: The present article presents the results...

  19. Why and How to Measure the Use of Electronic Resources

    Directory of Open Access Journals (Sweden)

    Jean Bernon

    2008-11-01

    Full Text Available A complete overview of library activity implies a complete and reliable measurement of the use of both electronic resources and printed materials. This measurement is based on three sets of definitions: document types, use types and user types. There is a common model of definitions for printed materials, but a lot of questions and technical issues remain for electronic resources. In 2006 a French national working group studied these questions. It relied on the COUNTER standard, but found it insufficient and pointed out the need for local tools such as web markers and deep analysis of proxy logs. Within the French national consortium COUPERIN, a new working group is testing ERMS, SUSHI standards, Shibboleth authentication, along with COUNTER standards, to improve the counting of the electronic resources use. At this stage this counting is insufficient and its improvement will be a European challenge for the future.

  20. MIMIC-compatible GaAs and InP field effect controlled transferred electron (FECTED) oscillators

    Science.gov (United States)

    Scheiber, Helmut; Luebke, Kurt; Diskus, Christian G.; Thim, Hartwig W.; Gruetzmacher, D.

    1989-12-01

    A MIMIC-(millimeter and microwave integrated circuit) compatible transferred electron oscillator is investigated which utilizes the frequency-independent negative resistance of the stationary charge dipole domain that forms in the channel of a MESFET. The device structure, analysis, and simulation are described. Devices fabricated from GaAs and InP exhibit very high power levels of 56 mW at 29 GHz and 55 mW at 34 GHz, respectively. Continuous wave power levels are somewhat lower (30 mW).

  1. Discontinuous Spirals of Stable Periodic Oscillations

    DEFF Research Database (Denmark)

    Sack, Achim; Freire, Joana G.; Lindberg, Erik

    2013-01-01

    We report the experimental discovery of a remarkable organization of the set of self-generated periodic oscillations in the parameter space of a nonlinear electronic circuit. When control parameters are suitably tuned, the wave pattern complexity of the periodic oscillations is found to increase...

  2. Search for muon to electron neutrino oscillations

    International Nuclear Information System (INIS)

    Vilain, P.; Wilquet, G.; Beyer, R.; Flegel, W.; Mouthuy, T.; Oeveraas, H.; Panman, J.; Rozanov, A.; Winter, K.; Zacek, G.; Zacek, V.; Buesser, F.W.; Foos, C.; Gerland, L.; Layda, T.; Niebergall, F.; Raedel, G.; Staehelin, P.; Voss, T.; Favart, D.; Gregoire, G.; Knoops, E.; Lemaitre, V.; Gorbunov, P.; Grigoriev, E.; Khovansky, V.; Maslennikov, A.; Lippich, W.; Nathaniel, A.; Staude, A.; Vogt, J.; Cocco, A.G.; Ereditato, A.; Fiorillo, G.; Marchetti-Stasi, F.; Palladino, V.; Strolin, P.; Capone, A.; De Pedis, D.; Dore, U.; Frenkel-Rambaldi, A.; Loverre, P.F.; Macina, D.; Piredda, G.; Santacesaria, R.; Di Capua, E.; Ricciardi, S.; Saitta, B.; Akkus, B.; Arik, E.; Serin-Zeyrek, M.; Sever, R.; Tolun, P.; Zeyrek, M.T.; Hiller, K.; Nahnhauer, R.; Roloff, H.E.

    1994-01-01

    A search for ν μ → ν e and anti ν μ → anti ν e oscillations has been carried out with the CHARM II detector exposed to the CERN wide band neutrino beam. The data were collected over five years, alternating beams mainly composed of muon-neutrinos and muon-antineutrinos. The number of interactions of ν e and anti ν e observed is comparable with the number of events expected from flux calculations. For large squared mass differences the upper limits obtained on the mixing angle are sin 2 2θ -3 for ν μ oscillating to ν e and sin 2 2θ -3 for anti ν μ to anti ν e , at the 90% confidence level. Combining neutrino and antineutrino data the upper limit is 5.6 . 10 -3 . (orig.)

  3. Red Shift and Broadening of Backward Harmonic Radiation from Electron Oscillations Driven by Femtosecond Laser Pulse

    International Nuclear Information System (INIS)

    Tian Youwei; Yu Wei; Lu Peixiang; Senecha, Vinod K; Han, Xu; Deng Degang; Li Ruxin; Xu Zhizhan

    2006-01-01

    The characteristics of backward harmonic radiation due to electron oscillations driven by a linearly polarized fs laser pulse are analysed considering a single electron model. The spectral distributions of the electron's backward harmonic radiation are investigated in detail for different parameters of the driver laser pulse. Higher order harmonic radiations are possible for a sufficiently intense driving laser pulse. We have shown that for a realistic pulsed photon beam, the spectrum of the radiation is red shifted as well as broadened because of changes in the longitudinal velocity of the electrons during the laser pulse. These effects are more pronounced at higher laser intensities giving rise to higher order harmonics that eventually leads to a continuous spectrum. Numerical simulations have further shown that by increasing the laser pulse width the broadening of the high harmonic radiations can be controlled

  4. Euler European Libraries and Electronic Resources in Mathematical Sciences

    CERN Document Server

    The Euler Project. Karlsruhe

    The European Libraries and Electronic Resources (EULER) Project in Mathematical Sciences provides the EulerService site for searching out "mathematical resources such as books, pre-prints, web-pages, abstracts, proceedings, serials, technical reports preprints) and NetLab (for Internet resources), this outstanding engine is capable of simple, full, and refined searches. It also offers a browse option, which responds to entries in the author, keyword, and title fields. Further information about the Project is provided at the EULER homepage.

  5. Investigation of a CDDW Hamiltonian to Explore Possibility of Magneto-Quantum Oscillations in Electronic Specific Heat of Hole-Doped Cuprates

    Directory of Open Access Journals (Sweden)

    Partha Goswami

    2010-01-01

    Full Text Available We investigate a chiral d-density wave (CDDW mean field model Hamiltonian in the momentum space suitable for the hole-doped cuprates, such as YBCO, in the pseudogap phase to obtain the Fermi surface (FS topologies, including the anisotropy parameter(́ and the elastic scattering by disorder potential (|0|. For ́=0, with the chemical potential =−0.27 eV for 10% doping level and |0|≥|| (where ||=0.25 eV is the first neighbor hopping, at zero/non-zero magnetic field (, the FS on the first Brillouin zone is found to correspond to electron pockets around antinodal regions and barely visible patches around nodal regions. For ́≠0, we find Pomeranchuk distortion of FS. We next relate our findings regarding FS to the magneto-quantum oscillations in the electronic specific heat. Since the nodal quasiparticle energy values for =0 are found to be greater than for |0|≥||, the origin of the oscillations for nonzero corresponds to the Fermi pockets around antinodal regions. The oscillations are shown to take place in the weak disorder regime (|0|=0.25eV only.

  6. Oscillating plasma bubbles. IV. Grids, geometry, and gradients

    Energy Technology Data Exchange (ETDEWEB)

    Stenzel, R. L. [Department of Physics and Astronomy, University of California, Los Angeles, California 90095-1547 (United States); Urrutia, J. M. [Urrutia Scientific, Van Nuys, California 91406 (United States)

    2012-08-15

    Plasma bubbles are created in an ambient plasma. The bubble is formed inside a cavity bounded by a negatively biased grid. Ions are injected through the grid and neutralized by electrons from either the background plasma or an internal electron emitter. The external electron supply is controlled by the grid bias relative to the external plasma potential. When the electron flux is restricted to the ion flux, the sheath of the bubble becomes unstable and causes the plasma potential to oscillate near the ion plasma frequency. The exact frequency depends on the net space charge density in the bubble sheath. The frequency increases with density and grid voltage, provided the grid forms a parallel equipotential surface. The present investigation shows that when the Debye length becomes smaller than the grid openings the electron flux cannot be controlled by the grid voltage. The frequency dependence on grid voltage and density is modified creating frequency and amplitude jumps. Low frequency sheath oscillations modulate the high frequency normal oscillations. Harmonics and subharmonics are excited by electrons in an ion-rich sheath. When the plasma parameters vary over the bubble surface, the sheath may oscillate at different frequencies. A cavity with two isolated grids has been used to investigate anisotropies of the energetic electron flux in a discharge plasma. The frequency dependence on grid voltage is entirely different when the grid controls the energetic electrons or the bulk electrons. These observations are important to several fields of basic plasma physics, such as sheaths, sheath instabilities, diagnostic probes, current, and space charge neutralization of ion beams.

  7. Neutrino wave function and oscillation suppression

    International Nuclear Information System (INIS)

    Dolgov, A.D.; Lychkovskiy, O.V.; Mamonov, A.A.; Okun, L.B.; Schepkin, M.G.

    2005-01-01

    We consider a thought experiment, in which a neutrino is produced by an electron on a nucleus in a crystal. The wave function of the oscillating neutrino is calculated assuming that the electron is described by a wave packet. If the electron is relativistic and the spatial size of its wave packet is much larger than the size of the crystal cell, then the wave packet of the produced neutrino has essentially the same size as the wave packet of the electron. We investigate the suppression of neutrino oscillations at large distances caused by two mechanisms: (1) spatial separation of wave packets corresponding to different neutrino masses; (2) neutrino energy dispersion for given neutrino mass eigenstates. We resolve the contributions of these two mechanisms. (orig.)

  8. SOLAR NEUTRINO PHYSICS OSCILLATIONS: SENSITIVITY TO THE ELECTRONIC DENSITY IN THE SUN'S CORE

    Energy Technology Data Exchange (ETDEWEB)

    Lopes, Ilidio [Centro Multidisciplinar de Astrofisica, Instituto Superior Tecnico, Universidade Tecnica de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); Turck-Chieze, Sylvaine, E-mail: ilidio.lopes@ist.utl.pt, E-mail: ilopes@uevora.pt, E-mail: sylvaine.turck-chieze@cea.fr [CEA/IRFU/Service d' Astrophysique, CE Saclay, F-91191 Gif sur Yvette (France)

    2013-03-01

    Solar neutrinos coming from different nuclear reactions are now detected with high statistics. Consequently, an accurate spectroscopic analysis of the neutrino fluxes arriving on Earth's detectors becomes available, in the context of neutrino oscillations. In this work, we explore the possibility of using this information to infer the radial profile of the electronic density in the solar core. So, we discuss the constraints on the Sun's density and chemical composition that can be determined from solar neutrino observations. This approach constitutes an independent and alternative diagnostic to the helioseismic investigations already done. The direct inversion method, which we propose to obtain the radial solar electronic density profile, is almost independent of the solar model.

  9. AN OSCILLATOR CONFIGURATION FOR FULL REALIZATION OF HARD X-RAY FREE ELECTRON LASER*

    Energy Technology Data Exchange (ETDEWEB)

    Kim, K.-J.; Kolodziej, T.; Lindberg, R. R.; Shu, D.; Shvyd' ko, Y.; Stoupin, S.; Maxwell, T.J.; Ding, Y.; Fawley, W. M.; Hastings, J.; Huang, Z; Krzywinski, J.; Marcus, G.; Qin, Weilun; Medvedev, N.; Zemella, J.; Blank, V.; Terentyev, S.

    2017-06-01

    An x-ray free electron laser oscillator (XFELO) is feasible by employing an X-ray cavity with Bragg mirrors such as diamond crystals. An XFELO at the 5th harmonic frequency may be implemented at the LCLS II using its 4 GeV superconducting linac, producing stable, fully coherent, high-spectral-purity hard x-rays. In addition, its output can be a coherent seed to the LCLS amplifier for stable, high-power, femto-second x-ray pulses. We summarize the recent progress in various R&D efforts addressing critical issues for realizing an XFELO at LCLS II.

  10. Effects of Electronic Information Resources Skills Training for Lecturers on Pedagogical Practices and Research Productivity

    Science.gov (United States)

    Bhukuvhani, Crispen; Chiparausha, Blessing; Zuvalinyenga, Dorcas

    2012-01-01

    Lecturers use various electronic resources at different frequencies. The university library's information literacy skills workshops and seminars are the main sources of knowledge of accessing electronic resources. The use of electronic resources can be said to have positively affected lecturers' pedagogical practices and their work in general. The…

  11. Oscillating between Conservation and Investment: A Grounded Theory of Students’ Strategies for Optimizing Personal Resources

    Directory of Open Access Journals (Sweden)

    Katja Hakel

    2015-06-01

    Full Text Available Students’ use of time and effort during their studies has been discussed exhaustively in mass media and educational research. In most cases, researchers try to give advice to teachers on how to get their students to become more active and engaged. The grounded theory presented in this article, however, challenges this approach by focusing on the students’ point of view. When interviewing students for this study, I soon realized that students only have a limited amount of time and effort at their disposal. Optimizing these personal resources emerged as their main concern. For the students, investing resources into one study activity always means having to reduce the amount of time and effort they can spend on other activities. They resolve their main concern by oscillating between conservation and investment strategies. Their decision regarding which type of strategy to use depends strongly on the students’ evaluation of their current situation.

  12. Quantum oscillations of conductivity in bismuth wires

    International Nuclear Information System (INIS)

    Condrea, Elena

    2011-01-01

    Measurements of the resistance of bismuth nanowires with several diameters and different quality reveal oscillations on the dependence of resistance under uniaxial strain at T = 4.2 K. Amplitude of oscillations is significant (38 %) at helium temperature and becomes smearing at T = 77 K. Observed oscillations originate from quantum size effect. A simple evaluation of period of oscillations allows us to identify the groups of carriers involved in transport. Calculated periods of 42.2 and 25.9 nm satisfy approximately the ratio 2:1 for two experimentally observed sets of oscillations from light and heavy electrons.

  13. Effects Of Local Oscillator Errors On Digital Beamforming

    Science.gov (United States)

    2016-03-01

    processor EF element factor EW electronic warfare FFM flicker frequency modulation FOV field-of-view FPGA field-programmable gate array FPM flicker...frequencies and also more difficult to measure [15]. 2. Flicker frequency modulation The source for flicker frequency modulation ( FFM ) is attributed to...a physical resonance mechanism of an oscillator or issues controlling electronic components. Some oscillators might not show FFM noise, which might

  14. MgH Rydberg series: Transition energies from electron propagator theory and oscillator strengths from the molecular quantum defect orbital method

    Science.gov (United States)

    Corzo, H. H.; Velasco, A. M.; Lavín, C.; Ortiz, J. V.

    2018-02-01

    Vertical excitation energies belonging to several Rydberg series of MgH have been inferred from 3+ electron-propagator calculations of the electron affinities of MgH+ and are in close agreement with experiment. Many electronically excited states with n > 3 are reported for the first time and new insight is given on the assignment of several Rydberg series. Valence and Rydberg excited states of MgH are distinguished respectively by high and low pole strengths corresponding to Dyson orbitals of electron attachment to the cation. By applying the Molecular Quantum Defect Orbital method, oscillator strengths for electronic transitions involving Rydberg states also have been determined.

  15. Electronic Commerce Resource Centers. An Industry--University Partnership.

    Science.gov (United States)

    Gulledge, Thomas R.; Sommer, Rainer; Tarimcilar, M. Murat

    1999-01-01

    Electronic Commerce Resource Centers focus on transferring emerging technologies to small businesses through university/industry partnerships. Successful implementation hinges on a strategic operating plan, creation of measurable value for customers, investment in customer-targeted training, and measurement of performance outputs. (SK)

  16. Quantized impedance dealing with the damping behavior of the one-dimensional oscillator

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Jinghao; Zhang, Jing; Li, Yuan; Zhang, Yong; Fang, Zhengji; Zhao, Peide, E-mail: pdzhao@eyou.com, E-mail: pdzhao@hebut.edu.cn [School of Science, Hebei University of Technology, Beichen Campus, Tianjin 300401 (China); Li, Erping, E-mail: liep@zju.edu.cn [Institute of High Performance Computing, Fusionopolis, 1 Fusionopolis Way, No. 16-16 Connexis, Singapore 138632 (Singapore)

    2015-11-15

    A quantized impedance is proposed to theoretically establish the relationship between the atomic eigenfrequency and the intrinsic frequency of the one-dimensional oscillator in this paper. The classical oscillator is modified by the idea that the electron transition is treated as a charge-discharge process of a suggested capacitor with the capacitive energy equal to the energy level difference of the jumping electron. The quantized capacitance of the impedance interacting with the jumping electron can lead the resonant frequency of the oscillator to the same as the atomic eigenfrequency. The quantized resistance reflects that the damping coefficient of the oscillator is the mean collision frequency of the transition electron. In addition, the first and third order electric susceptibilities based on the oscillator are accordingly quantized. Our simulation of the hydrogen atom emission spectrum based on the proposed method agrees well with the experimental one. Our results exhibits that the one-dimensional oscillator with the quantized impedance may become useful in the estimations of the refractive index and one- or multi-photon absorption coefficients of some nonmagnetic media composed of hydrogen-like atoms.

  17. Electron-beam generation, transport, and transverse oscillation experiments using the REX injector

    International Nuclear Information System (INIS)

    Carlson, R.L.; Allison, P.W.; Kauppila, T.J.; Moir, D.C.; Ridlon, R.N.

    1991-01-01

    The REX machine at LANL is being used as a prototype to generate a 4-MV, 4.5-kA, 55-ns flat-top electron beam as a source for injection into a linear induction accelerator of the 16-MeV Dual Axis Radiographic Hydrotest facility. The pulsed-power source drives a planar velvet cathode producing a beam that is accelerated through a foilless anode aperture and transported by an air core magnetic lens for injection into the first 48 linear induction cells. Extensive measurements of the time-resolved (<1-ns) properties of the beam using a streak camera and high-speed electronic diagnostics have been made. These parameters include beam current, voltage, current density, emittance, and transverse beam motion. The effective cathode temperature is 117 eV, corresponding to a Lapostolle emittance of 0.96 mm-rad. Transverse oscillations of the transported beam have been observed via a differenced B-dot technique to be about ±100 μ at 245 MHz. This beam motion has been correlated via detailed rf measurements of asymmetric transverse cavity modes in the A-K gap

  18. Realization of Electronically Tunable Current- Mode Multiphase Sinusoidal Oscillators Using CFTAs

    OpenAIRE

    Prungsak Uttaphut

    2012-01-01

    An implementation of current-mode multiphase sinusoidal oscillators is presented. Using CFTA-based lossy integrators, odd and odd/even phase systems can be realized with following advantages. The condition of oscillation and frequency of oscillation can be orthogonally tuned. The high output impedances facilitate easy driving an external load without additional current buffers. The proposed MSOs provide odd or even phase signals that are equally spaced in phase and equal amplitude. The circui...

  19. Study of the appearance of oscillating electron neutrinos issued from muon neutrino beam in the K2K experiment

    International Nuclear Information System (INIS)

    Argyriades, J.

    2006-05-01

    The work presented in this thesis has been done in the K2K experiment. His principle consists in the use of a beam of muon neutrinos, which flux has been measured at short and long distances. Those data enable us to study the effects of neutrino oscillation, particularly by measuring ν μ disappearance. Although this is not an appearance experiment, electronic neutrinos oscillation has been searched. In spite of no signal of appearance, this study enables to constrain oscillation parameters (Δm 23 2 , sin 2 2θ 13 ). With one event for 1,07 expected event from background, the exclusion area edges are close to the best actual limits, provided by Chooz experiment. By setting Δm 23 2 .= 2,8.10 -3 eV 2 , a limit at 90% confident level is reached: sin 2 2θ 13 < 0,2. (author)

  20. Electronically Tuned Local Oscillators for the NOEMA Interferometer

    Science.gov (United States)

    Mattiocco, Francois; Garnier, Olivier; Maier, Doris; Navarrini, Alessandro; Serres, Patrice

    2016-03-01

    We present an overview of the electronically tuned local oscillator (LO) system developed at the Institut de RadioAstronomie millimetrique (IRAM) for the superconductor-insulator-superconductor (SIS) receivers of the NOrthern Extended Millimeter Array interferometer (NOEMA). We modified the frequency bands and extended the bandwidths of the LO designs developed by the National Radio Astronomy Observatory (NRAO) for the Atacama Large Millimeter Array (ALMA) project to cover the four NOEMA LO frequency ranges 82-108.3 GHz (Band 1), 138.6-171.3 GHz (Band 2), 207.7-264.4 GHz (Band 3), and 283-365 GHz (Band 4). The NOEMA LO system employs commercially available MMICs and GaAs millimeter MMICs from NRAO which are micro-assembled into active multiplied chain (AMC) and power amplifier (PA) modules. We discuss the problem of the LO spurious harmonics and of the LO signal directly multiplied by the SIS mixers that add extra noise and lead to detections of unwanted spectral lines from higher order sidebands. A waveguide filter in the LO path is used to reduce the higher order harmonics level of the LO at the output of the final frequency multiplier, thus mitigating the undesired effects and improving the system noise temperature.

  1. Voltage-driven quantum oscillations in graphene

    International Nuclear Information System (INIS)

    Yampol'skii, V A; Savel'ev, S; Nori, Franco

    2008-01-01

    We predict unusual (for non-relativistic quantum mechanics) electron states in graphene, which are localized within a finite-width potential barrier. The density of localized states in the sufficiently high and/or wide graphene barrier exhibits a number of singularities at certain values of the energy. Such singularities provide quantum oscillations of both the transport (e.g. conductivity) and thermodynamic properties of graphene-when increasing the barrier height and/or width, similarly to the well-known Shubnikov-de-Haas (SdH) oscillations of conductivity in pure metals. However, here the SdH-like oscillations are driven by an electric field instead of the usual magnetically driven SdH-oscillations

  2. Passive mode locking and formation of dissipative solitons in electron oscillators with a bleaching absorber in the feedback loop

    Energy Technology Data Exchange (ETDEWEB)

    Ginzburg, N. S., E-mail: ginzburg@appl.sci-nnov.ru; Kocharovskaya, E. R.; Vilkov, M. N.; Sergeev, A. S. [Russian Academy of Sciences, Institute of Applied Physics (Russian Federation)

    2017-01-15

    The mechanisms of passive mode locking and formation of ultrashort pulses in microwave electron oscillators with a bleaching absorber in the feedback loop have been analyzed. It is shown that in the group synchronism regime in which the translational velocity of particles coincides with the group velocity of the electromagnetic wave, the pulse formation can be described by the equations known in the theory of dissipative solitons. At the same time, the regimes in which the translational velocity of electrons differs from the group velocity and the soliton being formed and moving along the electron beam consecutively (cumulatively) receives energy from various electron fractions are optimal for generating pulses with the maximal peak amplitudes.

  3. ON ESTIMATING INTERSTELLAR POLYCYCLIC AROMATIC HYDROCARBON ABUNDANCES WITH CALCULATED OSCILLATOR STRENGTHS

    International Nuclear Information System (INIS)

    Tan Xiaofeng; Bernstein, Lawrence; Cami, Jan; Salama, Farid

    2011-01-01

    Vibronic bands of polycyclic aromatic hydrocarbons (PAHs) in the UV/visible range are often used to estimate the abundances of PAHs in the interstellar medium by comparing laboratory-measured spectra with astronomical observations. We investigate the errors introduced by associating theoretical electronic oscillator strengths with individual vibronic bands when estimating the abundances of interstellar PAHs. The vibronic oscillator strengths of the 0-0 bands of nine PAHs with two to seven benzene rings, spanning in the 2800-6700 A spectral range, have been calculated using the Franck-Condon approximation and compared to their electronic oscillator strengths. It is found that the use of calculated electronic oscillator strengths rather than the more physically relevant vibronic oscillator strengths underestimates interstellar abundances of the nine PAHs under study, on average by a factor of about 2.4. It is recommended that vibronic oscillator strengths should be systematically used to analyze the vibronic spectra of specific PAHs and to estimate their abundances in the interstellar medium. An empirical correcting factor is suggested for the cases where the vibronic oscillator strengths are unknown for more realistic estimation of interstellar PAH abundances.

  4. Quantized impedance dealing with the damping behavior of the one-dimensional oscillator

    Directory of Open Access Journals (Sweden)

    Jinghao Zhu

    2015-11-01

    Full Text Available A quantized impedance is proposed to theoretically establish the relationship between the atomic eigenfrequency and the intrinsic frequency of the one-dimensional oscillator in this paper. The classical oscillator is modified by the idea that the electron transition is treated as a charge-discharge process of a suggested capacitor with the capacitive energy equal to the energy level difference of the jumping electron. The quantized capacitance of the impedance interacting with the jumping electron can lead the resonant frequency of the oscillator to the same as the atomic eigenfrequency. The quantized resistance reflects that the damping coefficient of the oscillator is the mean collision frequency of the transition electron. In addition, the first and third order electric susceptibilities based on the oscillator are accordingly quantized. Our simulation of the hydrogen atom emission spectrum based on the proposed method agrees well with the experimental one. Our results exhibits that the one-dimensional oscillator with the quantized impedance may become useful in the estimations of the refractive index and one- or multi-photon absorption coefficients of some nonmagnetic media composed of hydrogen-like atoms.

  5. Friedel oscillations in graphene

    DEFF Research Database (Denmark)

    Lawlor, J. A.; Power, S. R.; Ferreira, M.S.

    2013-01-01

    Symmetry breaking perturbations in an electronically conducting medium are known to produce Friedel oscillations in various physical quantities of an otherwise pristine material. Here we show in a mathematically transparent fashion that Friedel oscillations in graphene have a strong sublattice...... asymmetry. As a result, the presence of impurities and/or defects may impact the distinct graphene sublattices very differently. Furthermore, such an asymmetry can be used to explain the recent observations that nitrogen atoms and dimers are not randomly distributed in graphene but prefer to occupy one...

  6. Excitation of RF oscillations in a discharge with negative differential conductivity

    International Nuclear Information System (INIS)

    Antonov, A.N.; Kovpik, O.F.; Kornilov, E.A.

    2001-01-01

    The excitation of oscillations in a discharge with negative differential conductivity is studied experimentally. The possibility is demonstrated of amplifying oscillations in the cathode dark space at frequencies close to the electron plasma frequency of the positive-column plasma. The phase velocities of waves at these frequencies are determined. When the waves pass from the cathode dark space to the discharge positive column, their phase velocities decrease; the closer the frequency is to the electron plasma frequency, the more pronounced the decrease in the phase velocity. As the intensity of oscillations increases, the discharge becomes non-steady-state. This is confirmed by the time evolution of the current-voltage characteristic. The shape of the current-voltage characteristic, its splitting, and the rate at which it varies depend on the input RF power. The decrease in the cathode dark space indicates that the ionization processes in the discharge are strongly influenced by electron plasma oscillations excited due to the collective interaction of the electron beam formed at the cathode with the discharge plasma. It is these processes that determine the maximum values of both the frequency of the excited oscillations and the power that can be withdrawn from the discharge

  7. Preliminary design and optimization of a G-band extended interaction oscillator based on a pseudospark-sourced electron beam

    Energy Technology Data Exchange (ETDEWEB)

    Yin, Y., E-mail: yong.yin@strath.ac.uk, E-mail: yinyong@uestc.edu.cn [School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054 (China); Department of Physics, Scottish Universities Physics Alliance, University of Strathclyde, Glasgow G4 0NG (United Kingdom); He, W.; Zhang, L.; Yin, H.; Cross, A. W. [Department of Physics, Scottish Universities Physics Alliance, University of Strathclyde, Glasgow G4 0NG (United Kingdom)

    2015-07-15

    The design and simulation of a G-band extended interaction oscillator (EIO) driven by a pseudospark-sourced electron beam is presented. The characteristic of the EIO and the pseudospark-based electron beam were studied to enhance the performance of the newly proposed device. The beam-wave interaction of the EIO can be optimized by choosing a suitable pseudospark discharging voltage and by widening the operating voltage region of the EIO circuit. Simulation results show that a peak power of over 240 W can be achieved at G-band using a pseudospark discharge voltage of 41 kV.

  8. Temperature oscillating regimes in Tore Supra diagnosed by MHD activity

    International Nuclear Information System (INIS)

    Maget, P.; Imbeaux, F.; Giruzzi, G.; Udintsev, V.S.; Huysmans, G.T.A.; Segui, J.-L.; Goniche, M.; Moreau, Ph.; Sabot, R.; Garbet, X.

    2006-01-01

    This paper describes what we can learn on the regimes of spontaneous electron temperature oscillations discovered in Tore Supra from the analysis of MHD activity. Since the first observations of this oscillating behaviour of plasma equilibrium, and its interpretation as a predator-prey system involving lower hybrid waves power deposition and electron confinement, analysis of MHD modes has confirmed the reality of safety factor profile oscillations. This points towards the importance of rational values of the safety factor in the transition to transport barriers in reversed magnetic shear plasmas

  9. Exploring new features of neutrino oscillations with very low energy monoenergetic neutrinos

    CERN Document Server

    Vergados, J D

    2010-01-01

    In the present work we propose to study neutrino oscillations employing sources of monoenergetic neutrinos following electron capture by the nucleus. Since the neutrino energy is very low the smaller of the two oscillation lengths, L23, appearing in this electronic neutrino disappearance experiment can be so small that the full oscillation can take place inside the detector and one may determine very accurately the neutrino oscillation parameters. Since in this case the oscillation probability is proportional to theta13, one can measure or set a better limit on the unknown parameter theta13. This is quite important, since, if this mixing angle vanishes, there is not going to be CP violation in the leptonic sector. The best way to detect it is by measuring electron recoils in neutrino-electron scattering. One, however, has to pay the price that the expected counting rates are very small. Thus one needs a very intensive neutrino source and a large detector with as low as possible energy threshold and high energ...

  10. Electron-beam generation, transport, and transverse oscillation experiments using the REX injector

    International Nuclear Information System (INIS)

    Carlson, R.L.; Allison, P.W.; Kauppila, T.J.; Moir, D.C.; Ridlon, R.N.

    1991-01-01

    The REX machine at LANL is being used as a prototype to generate a 4-MV, 4.5-kA, 55-ns flat-top electron beam as a source for injection into a linear induction accelerator of the 16-MeV Dual-Axis Radiographic Hydrotest facility. The pulsed-power sources drives a planar velvet cathode producing a beam that is accelerated through a foilless anode aperture and transported by an air core magnetic lens for injection into the first of 48 linear induction cells. Extensive measurements of the time-resolved (<1-ns) properties of the beam using a streak camera and high-speed electronic diagnostics have been made. These parameters include beam current, voltage, current density, emittance, and transverse beam motion. The effective cathode temperature is 117 eV, corresponding to a Lapostolle emittance of 0.96 mm-rad. Transverse oscillations of the transported beam have been observed via a differenced B technique to be about ±100 μm at 245 MHz. This beam motion has been correlated via detailed rf measurements of asymmetric transverse cavity modes in the A-K gap. 7 refs., 6 figs

  11. David Shoenberg and the beauty of quantum oscillations

    Science.gov (United States)

    Pudalov, V. M.

    2011-01-01

    The quantum oscillation effect was discovered in Leiden in 1930, by W. J. de Haas and P. M. van Alphen when measuring magnetization, and by L. W. Shubnikov and de Haas when measuring magnetoresistance. Studying single crystals of bismuth, they observed oscillatory variations in the magnetization and magnetoresistance with magnetic field. Shoenberg, whose first research in Cambridge had been on bismuth, found that much stronger oscillations are observed when a bismuth sample is cooled to liquid helium temperature rather than liquid hydrogen, which had been used by de Haas. In 1938 Shoenberg went from Cambridge to Moscow to study these oscillations at Kapitza's Institute where liquid helium was available at that time. In 1947, J. Marcus observed similar oscillations in zinc and that persuaded Schoenberg to return to this research. After that, the dHvA effect became one of his main research topics. In particular, he developed techniques for quantitative measurement of this effect in many metals. A theoretical explanation of quantum oscillations was given by L. Onsager in 1952, and an analytical quantitative theory by I. M. Lifshitz and A. M. Kosevich in 1955. These theoretical advances seemed to provide a comprehensive description of the effect. Since then, quantum oscillations have been widely used as a tool for measuring Fermi surface extremal cross-sections and all-angle electron scattering times. In his pioneering experiments of the 1960's, Shoenberg revealed the richness and deep essence of the quantum oscillation effect and showed how the beauty of the effect is disclosed under nonlinear conditions imposed by interactions in the system under study. It was quite surprising that "magnetic interaction" conditions could cause the apparently weak quantum oscillation effect to have such strong consequences as breaking the sample into magnetic (now called "Shoenberg") domains and forming an inhomogeneous magnetic state. With his contributions to the field of quantum

  12. David Schoenberg and the beauty of quantum oscillations

    International Nuclear Information System (INIS)

    Pudalov, V.M.

    2012-01-01

    The quantum oscillation effect was discovered in Leiden, in 1930, by W.J. de Haas and P.M. van Alphen in magnetization measurement, and by L.W. Shubnikov and de Haas - in magnetoresistance. Studying single crystals of bismuth, they observed oscillatory variations of magnetization and magnetoresistance with magnetic field. Shoenberg, whose first research in Cambridge had been on bismuth, found that much stronger oscillations are observed when a bismuth sample is cooled to liquid helium rather than to liquid hydrogen, which had been used by de Haas. In 1938 Shoenberg came from Cambridge to Moscow to study these oscillations at Kapitza Institute where liquid helium was available at that time. In 1947, J. Marcus observed similar oscillations in zinc, that persuaded Shoenberg to return to this research, and, since then, the dHvA effect had been one of his main research topic. In particular, he developed techniques for quantitative measurements of the effect in many metals. Theoretical explanation of quantum oscillations was given by L. Onsager in 1952, and the analytical quantitative theory by I.M. Lifshitz and A.M. Kosevich in 1955. These theoretical advancements seemed to provide a comprehensive description of the effect. Since then, quantum oscillations were commonly considered as a tool for measuring Fermi surface extremal cross-sections and all-angle electron scattering times. However, in his pioneering experiments in 1960s, Shoenberg revealed the richness and deep essence of the quantum oscillation effect and showed how the beauty of the effect is disclosed under nonlinear conditions imposed by interactions in the system under study. It was quite unexpected, that under 'magnetic interaction' conditions, the apparently weak effect of quantum oscillations may lead to such strong consequences as breaking the sample into magnetic (now called 'Shoenberg') domains and the formation of an inhomogeneous magnetic state. Owing to his contribution to the field of quantum

  13. USE OF ELECTRONIC EDUCATIONAL RESOURCES WHEN TRAINING IN WORK WITH SPREADSHEETS

    Directory of Open Access Journals (Sweden)

    Х А Гербеков

    2017-12-01

    Full Text Available Today the tools for maintaining training courses based on opportunities of information and communication technologies are developed. Practically in all directions of preparation and on all subject matters electronic textbook and self-instruction manuals are created. Nevertheless the industry of computer educational and methodical materials actively develops and gets more and more areas of development and introduction. In this regard more and more urgent is a problem of development of the electronic educational resources adequate to modern educational requirements. Creation and the organization of training courses with use of electronic educational resources in particular on the basis of Internet technologies remains a difficult methodical task.In article the questions connected with development of electronic educational resources for use when studying the substantial line “Information technologies” of a school course of informatics in particular for studying of spreadsheets are considered. Also the analysis of maintenance of a school course and the unified state examination from the point of view of representation of task in him corresponding to the substantial line of studying “Information technologies” on mastering technology of information processing in spreadsheets and the methods of visualization given by means of charts and schedules is carried out.

  14. Study of the parasitic oscillations in a gyrotron; Etudes des oscillations parasites dans un gyrotron

    Energy Technology Data Exchange (ETDEWEB)

    Pedrozzi, M. [Ecole Polytechnique Federale, Lausanne (Switzerland). Centre de Recherche en Physique des Plasma (CRPP)

    1997-01-01

    This work is dedicated to the study of parasitic instabilities in a gyrotron, and to the influence of such instabilities on the interaction efficiency. The gyrotron is a high-power millimeter wave radiation source, based on the resonant interaction between a weakly relativistic electron beam immersed in a guiding magnetic field, and an electromagnetic wave. The gyrotron investigated here operates at a frequency close to 100 GHz: its main feature is that it is quasi optical. In this configuration, the electron beam interacts with a high order TEM eigenmode of a Fabry-Perot resonator, the axis of which is perpendicular to the electron beam path. During the development of this source, the highest efficiency that was achieved is approximately 30% lower than the theoretical predictions. At the same time, parasitic oscillations at frequencies close to the maximum relativistic cyclotronic frequency are detected. The power associated with these oscillations ranges from a few watts to a few kilowatts, with threshold currents of the order of 100 mA. It is suspected that the excitation of parasitic oscillations in the beam duct section before the interaction region might have a dramatic effect on the electron beam distribution function inducing, in particular, an energy spread. The cyclotron maser instability responsible for the energy exchange between particles and fields in a gyrotron, is very sensitive to energy spreads. It is thus necessary to identify the origin of the parasitic radiation. A few physical mechanisms suspected to lead to a degradation of the electron beam properties were investigated: the cyclotron maser process itself, the Bernstein electrostatic instability and the Langmuir instability. The experimental work concentrated on the study of the beam ducts between the electron gun and the resonant cavity. (author) figs., tabs., 90 refs.

  15. Report on first masing and single mode locking in a prebunched beam FEM oscillator

    Energy Technology Data Exchange (ETDEWEB)

    Cohen, M.; Eichenbaum, A.; Kleinman, H. [Tel-Aviv Univ., Ramat-Aviv (Israel)] [and others

    1995-12-31

    Radiation characteristics of a table-top free electron maser (FEM) are described in this paper. The FEM employs a prebunched electron beam and is operated as an oscillator in the low-gain collective (Raman) regime. Using electron beam prebunching single mode locking at any one of the possible oscillation modes was obtained. The electron beam is prebunched by a microwave tube section before it is injected into the wiggler. By tuning the electron beam bunching frequency, the FEM oscillation frequency can be locked to any eigen frequency of the resonant waveguide cavity which is within the frequency band of net gain of the FEM. The oscillation build up process is sped up, when the FEM operates with a prebunched electron beam, and the build-up time of radiation is shortened significantly. First measurements of masing with and without prebunching and characterization of the emitted radiation are reported.

  16. The influence of core-valence electron correlations on the convergence of energy levels and oscillator strengths of ions with an open 3d shell using Fe VIII as an example

    International Nuclear Information System (INIS)

    Zeng Jiaolong; Jin Fengtao; Zhao Gang; Yuan Jianmin

    2003-01-01

    Accurate atomic data, such as fine structure energy levels and oscillator strengths of different ionization stages of iron ions, are important for astrophysical and laboratory plasmas. However, some important existing oscillator strengths for ions with an open 3d shell found in the literature might not be accurate enough for practical applications. As an example, the present paper checks the convergence behaviour of the energy levels and oscillator strengths of Fe VIII by systematically increasing the 3p n -3d n (n = 1, 2, 3 and 6) core-valence electron correlations using the multiconfiguration Hartree-Fock method. The results show that one should at least include up to 3p 3 -3d 3 core-valence electron correlations to obtain converged results. Large differences are found between the present oscillator strengths and other theoretical results in the literature for some strong transitions

  17. Plasma and oscillations with contributions in memoriam including a complete bibliography of his works

    CERN Document Server

    Suits, C Guy

    1961-01-01

    The Collected Works of Irving Langmuir, Volume 5: Plasma and Oscillations is an 11-chapter text covers the extensive research study of Langmuir in the field of gas discharges. This book specifically tackles oscillations in ionized gases. The opening chapters describe the plasma-boundary phenomena and the use of a probe to separate the primary electron beam from the scattered electrons. The succeeding chapters deal with the collisions between electrons and gas molecules, oscillations in ionized gases, and the interaction of electron and positive ion space charges in cathode sheaths. These t

  18. Recovery of the Aharonov-Bohm oscillations in asymmetrical quantum rings

    Energy Technology Data Exchange (ETDEWEB)

    Voskoboynikov, O., E-mail: vam@faculty.nctu.edu.tw [Department of Electronics Engineering, National Chiao Tung University, Hsinchu, Taiwan (China)

    2016-07-15

    We theoretically investigate suppression and recovery of the Aharonov-Bohm oscillations of the diamagnetic response of electrons (holes) confined in self-assembled In{sub c}Ga{sub 1−c}As/GaAs semiconductor reflection asymmetrical quantum rings. Based on the mapping method and gauge-origin-independent definition for the magnetic vector potential we simulate the energies and wave functions of the electron (hole) under external magnetic and electric fields. We examine the transformation of the ground state wave function of the electron (hole) in reflection asymmetrical rings from localized in one of the potential valleys (dotlike shape of the wave function) to distributed over all volume of the ring (ringlike shape) under an appropriate lateral electric field. This transformation greatly recovers the electron (hole) diamagnetic coefficient and Aharonov-Bohm oscillations of the diamagnetic response of the ring. However, the recovering electric field for the first Aharonov-Bohm diamagnetic oscillation of the electron is a suppressing one for the hole (and vice versa). This can block the recovery of the optical Aharonow-Bohm effect in In{sub c}Ga{sub 1−c}As/GaAs asymmetrically wobbled rings. However, the recovery of the Aharonov-Bohm oscillations for the independent electron (hole) by the external electric field remains interesting and feasible objective for the asymmetric rings.

  19. Graphene surface plasmon polaritons with opposite in-plane electron oscillations along its two surfaces

    International Nuclear Information System (INIS)

    Liang, Huawei; Ruan, Shuangchen; Zhang, Min; Su, Hong; Li, Irene Ling

    2015-01-01

    We predict the existence of a surface plasmon polariton (SPP) mode that can be guided by a graphene monolayer, regardless of the sign of the imaginary part of its conductivity. In this mode, in-plane electron oscillations along two surfaces of graphene are of opposite directions, which is very different from conventional SPPs on graphene. Significantly, coating graphene with dielectric films yields a way to guide the SPPs with both sub-wavelength mode widths and ultra-long propagation distances. In particular, the mode characteristics are very sensitive to the chemical potential of graphene, so the graphene-based waveguide can find applications in many optoelectronic devices

  20. Graphene surface plasmon polaritons with opposite in-plane electron oscillations along its two surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Liang, Huawei; Ruan, Shuangchen, E-mail: scruan@szu.edu.cn; Zhang, Min; Su, Hong; Li, Irene Ling [Shenzhen Key Laboratory of Laser Engineering, College of Optoelectronic Engineering, Shenzhen University, Shenzhen 518060 (China); Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, Shenzhen University, Shenzhen 518060 (China)

    2015-08-31

    We predict the existence of a surface plasmon polariton (SPP) mode that can be guided by a graphene monolayer, regardless of the sign of the imaginary part of its conductivity. In this mode, in-plane electron oscillations along two surfaces of graphene are of opposite directions, which is very different from conventional SPPs on graphene. Significantly, coating graphene with dielectric films yields a way to guide the SPPs with both sub-wavelength mode widths and ultra-long propagation distances. In particular, the mode characteristics are very sensitive to the chemical potential of graphene, so the graphene-based waveguide can find applications in many optoelectronic devices.

  1. Smith-Purcell oscillator in an exponential gain regime

    International Nuclear Information System (INIS)

    Schachter, L.; Ron, A.

    1988-01-01

    A Smith-Purcell oscillator with a thick electron beam is analyzed in its exponential gain regime. A threshold current less than 1[A] is found for a 1 mm wavelength; this threshold is much lower than that of a similar oscillator operating in a linear gain regime

  2. New neutrino oscillation results from NOVA

    CERN Multimedia

    CERN. Geneva

    2018-01-01

    Neutrinos oscillate among flavors as they travel because a neutrino of a particular flavor is also a superposition of multiple neutrinos with slightly different masses.  The interferometric nature of oscillations allows these tiny mass differences to be measured, along with the parameters of the PMNS matrix which governs the mixing. However, since neutrinos only interact weakly, a powerful neutrino source and massive detectors are required to measure them. In this talk I will show recently updated results from NOvA, a long-baseline neutrino oscillation experiment at Fermilab with two functionally identical scintillator detectors. I will present measurements of muon neutrino disappearance and electron neutrino appearance, and what constraints those measurements put on the remaining open questions in neutrino oscillations: Is the neutrino mass hierarchy "normal" or "inverted?" Do neutrino oscillations violate CP symmetry? Is the mixing in the atmospheric sector maximal? The recent update includes 50%...

  3. X-ray comb generation from nuclear-resonance-stabilized x-ray free-electron laser oscillator for fundamental physics and precision metrology

    Directory of Open Access Journals (Sweden)

    B. W. Adams

    2015-03-01

    Full Text Available An x-ray free-electron laser oscillator (XFELO is a next-generation x-ray source, similar to free-electron laser oscillators at VUV and longer wavelengths but using crystals as high-reflectivity x-ray mirrors. Each output pulse from an XFELO is fully coherent with high spectral purity. The temporal coherence length can further be increased drastically, from picoseconds to microseconds or even longer, by phase-locking successive XFELO output pulses, using the narrow nuclear resonance lines of nuclei such as ^{57}Fe as a reference. We show that the phase fluctuation due to the seismic activities is controllable and that due to spontaneous emission is small. The fluctuation of electron-bunch spacing contributes mainly to the envelope fluctuation but not to the phase fluctuation. By counting the number of standing-wave maxima formed by the output of the nuclear-resonance-stabilized (NRS XFELO over an optically known length, the wavelength of the nuclear resonance can be accurately measured, possibly leading to a new length or frequency standard at x-ray wavelengths. A NRS-XFELO will be an ideal source for experimental x-ray quantum optics as well as other fundamental physics. The technique can be refined for other, narrower resonances such as ^{181}Ta or ^{45}Sc.

  4. Analytical Study of Usage of Electronic Information Resources at Pharmacopoeial Libraries in India

    Directory of Open Access Journals (Sweden)

    Sunil Tyagi

    2014-02-01

    Full Text Available The objective of this study is to know the rate and purpose of the use of e-resource by the scientists at pharmacopoeial libraries in India. Among other things, this study examined the preferences of the scientists toward printed books and journals, electronic information resources, and pattern of using e-resources. Non-probability sampling specially accidental and purposive technique was applied in the collection of primary data through administration of user questionnaire. The sample respondents chosen for the study consists of principle scientific officer, senior scientific officer, scientific officer, and scientific assistant of different division of the laboratories, namely, research and development, pharmaceutical chemistry, pharmacovigilance, pharmacology, pharmacogonosy, and microbiology. The findings of the study reveal the personal experiences and perceptions they have had on practice and research activity using e-resource. The major findings indicate that of the total anticipated participants, 78% indicated that they perceived the ability to use computer for electronic information resources. The data analysis shows that all the scientists belonging to the pharmacopoeial libraries used electronic information resources to address issues relating to drug indexes and compendia, monographs, drugs obtained through online databases, e-journals, and the Internet sources—especially polices by regulatory agencies, contacts, drug promotional literature, and standards.

  5. Limited and time-delayed internal resource allocation generates oscillations and chaos in the dynamics of citrus crops

    International Nuclear Information System (INIS)

    Ye, Xujun; Sakai, Kenshi

    2013-01-01

    Alternate bearing or masting is a yield variability phenomenon in perennial crops. The complex dynamics in this phenomenon have stimulated much ecological research. Motivated by data from an eight-year experiment with forty-eight individual trees, we explored the mechanism inherent to these dynamics in Satsuma mandarin (Citrus unshiu Marc.). By integrating high-resolution imaging technology, we found that the canopy structure and reproduction output of individual citrus crops are mutually dependent on each other. Furthermore, it was revealed that the mature leaves in early season contribute their energy to the fruiting of the current growing season, whereas the younger leaves show a delayed contribution to the next growing season. We thus hypothesized that the annual yield variability might be caused by the limited and time-delayed resource allocation in individual plants. A novel lattice model based on this hypothesis demonstrates that this pattern of resource allocation will generate oscillations and chaos in citrus yield

  6. Limited and time-delayed internal resource allocation generates oscillations and chaos in the dynamics of citrus crops

    Energy Technology Data Exchange (ETDEWEB)

    Ye, Xujun, E-mail: yexujun@cc.hirosaki-u.ac.jp [College of Biosystems Engineering and Food Science, Zhejiang University, Hangzhou 310058 (China); Faculty of Agriculture and Life Sciences, Hirosaki University, Aomori 036-8561 (Japan); Sakai, Kenshi, E-mail: ken@cc.tuat.ac.jp [Environmental and Agricultural Engineering Department, Tokyo University of Agriculture and Technology, Tokyo 183-8509 (Japan)

    2013-12-15

    Alternate bearing or masting is a yield variability phenomenon in perennial crops. The complex dynamics in this phenomenon have stimulated much ecological research. Motivated by data from an eight-year experiment with forty-eight individual trees, we explored the mechanism inherent to these dynamics in Satsuma mandarin (Citrus unshiu Marc.). By integrating high-resolution imaging technology, we found that the canopy structure and reproduction output of individual citrus crops are mutually dependent on each other. Furthermore, it was revealed that the mature leaves in early season contribute their energy to the fruiting of the current growing season, whereas the younger leaves show a delayed contribution to the next growing season. We thus hypothesized that the annual yield variability might be caused by the limited and time-delayed resource allocation in individual plants. A novel lattice model based on this hypothesis demonstrates that this pattern of resource allocation will generate oscillations and chaos in citrus yield.

  7. Page 170 Use of Electronic Resources by Undergraduates in Two ...

    African Journals Online (AJOL)

    undergraduate students use electronic resources such as NUC virtual library, HINARI, ... web pages articles from magazines, encyclopedias, pamphlets and other .... of Nigerian university libraries have Internet connectivity, some of the system.

  8. Magnetron with smooth anode. Statistical theory and ordered oscillations; Magnetron a anode lisse. Theorie statistique et oscillations ordonnees

    Energy Technology Data Exchange (ETDEWEB)

    Coste, J.

    1961-03-15

    We have to investigate the equilibrium regime that appears between a hot cathode and the electronic cloud that is confined around the cathode by a magnetic field parallel to its axis. The densities being high enough to involve the effect of space charge. The challenge of the magnetron theory is to face 2 issues: first the structure of the electronic cloud in a diode submitted to a magnetic field and secondly the oscillations that are likely to appear in this cloud. In this work we have made 2 attempts to clarify the situation, we have extended the classical theory of the static charge of space through a study of its oscillation modes on one hand and on the other hand we have tackled the issue of the structure of the electronic cloud with the tool of statistics. This document is divided into 2 chapters. In the first chapter we present a static study of the magnetron in which we take a statistical approach deliberately. We give answers to the issue of the thermodynamical equilibrium of the electronic cloud and we have found a mode very close to the Brillouin mode. The statistical approach has made us discuss the boundary conditions on the cathode, it means the coupling between the cathode and the electronic cloud. In the second chapter we present the theoretical study of the oscillations in a magnetron operating in the Brillouin mode. The resonances that appear in experimental data stay difficult to explain.

  9. El Niño-Southern Oscillation and water resources in the headwaters region of the Yellow River: links and potential for forecasting

    Directory of Open Access Journals (Sweden)

    A. Lü

    2011-04-01

    Full Text Available This research explores the rainfall-El Niño-Southern Oscillation (ENSO and runoff-ENSO relationships and examines the potential for water resource forecasting using these relationships. The Southern Oscillation Index (SOI, Niño1.2, Niño3, Niño4, and Niño3.4 were selected as ENSO indicators for cross-correlation analyses of precipitation and runoff. There was a significant correlation (95% confidence level between precipitation and ENSO indicators during three periods: January, March, and from September to November. In addition, monthly streamflow and monthly ENSO indictors were significantly correlated during three periods: from January to March, June, and from October to December (OND, with lag periods between one and twelve months. Because ENSO events can be accurately predicted one to two years in advance using physical modeling of the coupled ocean-atmosphere system, the lead time for forecasting runoff using ENSO indicators in the Headwaters Region of the Yellow River could extend from one to 36 months. Therefore, ENSO may have potential as a powerful forecasting tool for water resources in the headwater regions of Yellow River.

  10. All-Pass Filter Based Linear Voltage Controlled Quadrature Oscillator

    Directory of Open Access Journals (Sweden)

    Koushick Mathur

    2017-01-01

    Full Text Available A linear voltage controlled quadrature oscillator implemented from a first-order electronically tunable all-pass filter (ETAF is presented. The active element is commercially available current feedback amplifier (AD844 in conjunction with the relatively new Multiplication Mode Current Conveyor (MMCC device. Electronic tunability is obtained by the control node voltage (V of the MMCC. Effects of the device nonidealities, namely, the parasitic capacitors and the roll-off poles of the port-transfer ratios of the device, are shown to be negligible, even though the usable high-frequency ranges are constrained by these imperfections. Subsequently the filter is looped with an electronically tunable integrator (ETI to implement the quadrature oscillator (QO. Experimental responses on the voltage tunable phase of the filter and the linear-tuning law of the quadrature oscillator up to 9.9 MHz at low THD are verified by simulation and hardware tests.

  11. Model of e-learning with electronic educational resources of new generation

    Directory of Open Access Journals (Sweden)

    A. V. Loban

    2017-01-01

    Full Text Available Purpose of the article: improving of scientific and methodical base of the theory of the е-learning of variability. Methods used: conceptual and logical modeling of the е-learning of variability process with electronic educational resource of new generation and system analysis of the interconnection of the studied subject area, methods, didactics approaches and information and communication technologies means. Results: the formalization complex model of the е-learning of variability with electronic educational resource of new generation is developed, conditionally decomposed into three basic components: the formalization model of the course in the form of the thesaurusclassifier (“Author of e-resource”, the model of learning as management (“Coordination. Consultation. Control”, the learning model with the thesaurus-classifier (“Student”. Model “Author of e-resource” allows the student to achieve completeness, high degree of didactic elaboration and structuring of the studied material in triples of variants: modules of education information, practical task and control tasks; the result of the student’s (author’s of e-resource activity is the thesaurus-classifier. Model of learning as management is based on the principle of personal orientation of learning in computer environment and determines the logic of interaction between the lecturer and the student when determining the triple of variants individually for each student; organization of a dialogue between the lecturer and the student for consulting purposes; personal control of the student’s success (report generation and iterative search for the concept of the class assignment in the thesaurus-classifier before acquiring the required level of training. Model “Student” makes it possible to concretize the learning tasks in relation to the personality of the student and to the training level achieved; the assumption of the lecturer about the level of training of a

  12. Weiss oscillations and particle-hole symmetry at the half-filled Landau level

    Science.gov (United States)

    Cheung, Alfred K. C.; Raghu, S.; Mulligan, Michael

    2017-06-01

    Particle-hole symmetry in the lowest Landau level of the two-dimensional electron gas requires the electrical Hall conductivity to equal ±e2/2 h at half filling. We study the consequences of weakly broken particle-hole symmetry for magnetoresistance oscillations about half filling in the presence of an applied periodic one-dimensional electrostatic potential using the Dirac composite fermion theory proposed by Son [Son, Phys. Rev. X 5, 031027 (2015), 10.1103/PhysRevX.5.031027]. At fixed electron density, the oscillation minima are asymmetrically biased towards higher magnetic fields, while at fixed magnetic field the oscillations occur symmetrically as the electron density is varied about half filling. We find an approximate "sum rule" obeyed for all pairs of oscillation minima that can be tested in experiment. The locations of the magnetoresistance oscillation minima for the composite fermion theory of Halperin, Lee, and Read (HLR) and its particle-hole conjugate agree exactly. Within the current experimental resolution, the locations of the oscillation minima produced by the Dirac composite fermion coincide with those of HLR. These results may indicate that all three composite fermion theories describe the same long-wavelength physics.

  13. A survey of the use of electronic scientific information resources among medical and dental students

    Directory of Open Access Journals (Sweden)

    Aarnio Matti

    2006-05-01

    Full Text Available Abstract Background To evaluate medical and dental students' utilization of electronic information resources. Methods A web survey sent to 837 students (49.9% responded. Results Twenty-four per cent of medical students and ninteen per cent of dental students searched MEDLINE 2+ times/month for study purposes, and thiry-two per cent and twenty-four per cent respectively for research. Full-text articles were used 2+ times/month by thirty-three per cent of medical and ten per cent of dental students. Twelve per cent of respondents never utilized either MEDLINE or full-text articles. In multivariate models, the information-searching skills among students were significantly associated with use of MEDLINE and full-text articles. Conclusion Use of electronic resources differs among students. Forty percent were non-users of full-text articles. Information-searching skills are correlated with the use of electronic resources, but the level of basic PC skills plays not a major role in using these resources. The student data shows that adequate training in information-searching skills will increase the use of electronic information resources.

  14. Access to electronic information resources by students of federal ...

    African Journals Online (AJOL)

    The paper discusses access to electronic information resources by students of Federal Colleges of Education in Eha-Amufu and Umunze. Descriptive survey design was used to investigate sample of 526 students. Sampling technique used was a Multi sampling technique. Data for the study were generated using ...

  15. Adoption and use of electronic information resources by medical ...

    African Journals Online (AJOL)

    This study investigated the adoption and use of electronic information resources by medical science students of the University of Benin. The descriptive survey research design was adopted for the study and 390 students provided the data. Data collected were analysed with descriptive Statistics(Simple percentage and ...

  16. Activity patterns in networks stabilized by background oscillations.

    Science.gov (United States)

    Hoppensteadt, Frank

    2009-07-01

    The brain operates in a highly oscillatory environment. We investigate here how such an oscillating background can create stable organized behavior in an array of neuro-oscillators that is not observable in the absence of oscillation, much like oscillating the support point of an inverted pendulum can stabilize its up position, which is unstable without the oscillation. We test this idea in an array of electronic circuits coming from neuroengineering: we show how the frequencies of the background oscillation create a partition of the state space into distinct basins of attraction. Thus, background signals can stabilize persistent activity that is otherwise not observable. This suggests that an image, represented as a stable firing pattern which is triggered by a voltage pulse and is sustained in synchrony or resonance with the background oscillation, can persist as a stable behavior long after the initial stimulus is removed. The background oscillations provide energy for organized behavior in the array, and these behaviors are categorized by the basins of attraction determined by the oscillation frequencies.

  17. Magnetoresistance oscillations of two-dimensional electron systems in lateral superlattices with structured unit cells

    Science.gov (United States)

    Gerhardts, Rolf R.

    2015-11-01

    Model calculations for commensurability oscillations of the low-field magnetoresistance of two-dimensional electron systems (2DES) in lateral superlattices, consisting of unit cells with an internal structure, are compared with recent experiments. The relevant harmonics of the effective modulation potential depend not only on the geometrical structure of the modulated unit cell, but also strongly on the nature of the modulation. While higher harmonics of an electrostatically generated surface modulation are exponentially damped at the position of the 2DES about 90 nm below the surface, no such damping appears for strain-induced modulation generated, e.g., by the deposition of stripes of calixarene resist on the surface before cooling down the sample.

  18. First operation of the Los Alamos free-electron laser oscillator

    International Nuclear Information System (INIS)

    Warren, R.W.; Newnam, B.E.; Stein, W.E.

    1983-01-01

    An FEL oscillator has been operated at wavelengths between 9 and 11 μm with a peak intracavity power of about 20 MW and an average output power of 1 kW in 70- μs pulses. We present the design parameters and operating characteristics. We report measurements of spontaneous emission, start-up of oscillations, and signal growth through approx. 9 orders of magnitude to saturation. The dependence of gain and saturation on cavity length, alignment, beam parameters, and other critical variables are discussed and compared with theory. 7 references

  19. Oscillations of the Outer Boundary of the Outer Radiation Belt During Sawtooth Oscillations

    Directory of Open Access Journals (Sweden)

    Jae-Hun Kim

    2006-09-01

    Full Text Available We report three sawtooth oscillation events observed at geosynchronous orbit where we find quasi-periodic (every 2-3 hours sudden flux increases followed by slow flux decreases at the energy levels of ˜50-400 keV. For these three sawtooth events, we have examined variations of the outer boundary of the outer radiation belt. In order to determine L values of the outer boundary, we have used data of relativistic electron flux observed by the SAMPEX satellite. We find that the outer boundary of the outer radiation belt oscillates periodically being consistent with sawtooth oscillation phases. Specifically, the outer boundary of the outer radiation belt expands (namely, the boundary L value increases following the sawtooth particle flux enhancement of each tooth, and then contracts (namely, the boundary L value decreases while the sawtooth flux decreases gradually until the next flux enhancement. On the other hand, it is repeatedly seen that the asymmetry of the magnetic field intensity between dayside and nightside decreases (increases due to the dipolarization (the stretching on the nightside as the sawtooth flux increases (decreases. This implies that the periodic magnetic field variations during the sawtooth oscillations are likely responsible for the expansion-contraction oscillations of the outer boundary of the outer radiation belt.

  20. Entanglement in neutrino oscillations

    Energy Technology Data Exchange (ETDEWEB)

    Blasone, M.; Dell' Anno, F.; De Siena, S.; Illuminati, F. [Universita degli Studi di Salerno Via Ponte don Melillon, Dipt. di Matematica e Informatica, Fisciano SA (Italy); INFN Sezione di Napoli, Gruppo collegato di Salerno - Baronissi SA (Italy); Dell' Anno, F.; De Siena, S.; Illuminati, F. [CNR-INFM Coherentia - Napoli (Italy); Blasone, M. [ISI Foundation for Scientific Interchange, Torino (Italy)

    2009-03-15

    Flavor oscillations in elementary particle physics are related to multimode entanglement of single-particle states. We show that mode entanglement can be expressed in terms of flavor transition probabilities, and therefore that single-particle entangled states acquire a precise operational characterization in the context of particle mixing. We treat in detail the physically relevant cases of two- and three-flavor neutrino oscillations, including the effective measure of CP violation. We discuss experimental schemes for the transfer of the quantum information encoded in single-neutrino states to spatially delocalized two-flavor charged-lepton states, thus showing, at least in principle, that single-particle entangled states of neutrino mixing are legitimate physical resources for quantum information tasks. (authors)

  1. Entanglement in neutrino oscillations

    International Nuclear Information System (INIS)

    Blasone, M.; Dell'Anno, F.; De Siena, S.; Illuminati, F.; Dell'Anno, F.; De Siena, S.; Illuminati, F.; Blasone, M.

    2009-01-01

    Flavor oscillations in elementary particle physics are related to multimode entanglement of single-particle states. We show that mode entanglement can be expressed in terms of flavor transition probabilities, and therefore that single-particle entangled states acquire a precise operational characterization in the context of particle mixing. We treat in detail the physically relevant cases of two- and three-flavor neutrino oscillations, including the effective measure of CP violation. We discuss experimental schemes for the transfer of the quantum information encoded in single-neutrino states to spatially delocalized two-flavor charged-lepton states, thus showing, at least in principle, that single-particle entangled states of neutrino mixing are legitimate physical resources for quantum information tasks. (authors)

  2. Where Do Electronic Books Fit in the College Research Arsenal of Resources?

    Science.gov (United States)

    Barbier, Patricia

    2007-01-01

    Student use of electronic books has become an accepted supplement to traditional resources. Student use and satisfaction was monitored through an online course discussion board. Increased use of electronic books indicate this service is an accepted supplement to the print book collection.

  3. A study of muon neutrino to electron neutrino oscillations in the MINOS experiment

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Tingjun [Stanford Univ., CA (United States)

    2009-03-01

    The observation of neutrino oscillations (neutrino changing from one flavor to another) has provided compelling evidence that the neutrinos have non-zero masses and that leptons mix, which is not part of the original Standard Model of particle physics. The theoretical framework that describes neutrino oscillation involves two mass scales (Δmatm2 and Δmsol2), three mixing angles (θ12, θ23, and θ13) and one CP violating phase (δCP). Both mass scales and two of the mixing angles (θ12 and θ23) have been measured by many neutrino experiments. The mixing angle θ13, which is believed to be very small, remains unknown. The current best limit on θ13 comes from the CHOOZ experiment: θ13 < 11° at 90% C.L. at the atmospheric mass scale. δCP is also unknown today. MINOS, the Main Injector Neutrino Oscillation Search, is a long baseline neutrino experiment based at Fermi National Accelerator Laboratory. The experiment uses a muon neutrino beam, which is measured 1 km downstream from its origin in the Near Detector at Fermilab and then 735 km later in the Far Detector at the Soudan mine. By comparing these two measurements, MINOS can obtain parameters in the atmospheric sector of neutrino oscillations. MINOS has published results on the precise measurement of Δmatm2 and θ23 through the disappearance of muon neutrinos in the Far Detector and on a search for sterile neutrinos by looking for a deficit in the number of neutral current interactions seen in the Far Detector. MINOS also has the potential to improve the limit on the neutrino mixing angle θ13 or make the first measurement of its value by searching for an electron neutrino appearance signal in the Far Detector. This is the focus of the study presented in this thesis. We developed a neural network based algorithm to

  4. Electronically tunable femtosecond all-fiber optical parametric oscillator for multi-photon microscopy

    Science.gov (United States)

    Hellwig, Tim; Brinkmann, Maximilian; Fallnich, Carsten

    2018-02-01

    We present a femtosecond fiber-based optical parametric oscillator (FOPO) for multiphoton microscopy with wavelength tuning by electronic repetition rate tuning in combination with a dispersive filter in the FOPO cavity. The all-spliced, all-fiber FOPO cavity is based on polarization-maintaining fibers and a broadband output coupler, allowing to get access to the resonant signal pulses as well as the idler pulses simultaneously. The system was pumped by a gain-switched fiber-coupled laser diode emitting pulses at a central wavelength of 1030 nm and an electronically tunable repetition frequency of about 2 MHz. The pump pulses were amplified in an Ytterbium fiber amplifier system with a pulse duration after amplification of 13 ps. Tuning of the idler (1140 nm - 1300 nm) and signal wavelengths (850 nm - 940 nm) was achieved by changing the repetition frequency of the pump laser by about 4 kHz. The generated signal pulses reached a pulse energy of up to 9.2 nJ at 920 nm and were spectrally broadened to about 6 nm in the FOPO by a combination of self-phase and cross-phase modulation. We showed external compression of the idler pulses at 920 nm to about 430 fs and appleid them to two-photon excitation microscopy with green fluorescent dyes. The presented system constitutes an important step towards a fully fiber-integrated all-electronically tunable and, thereby, programmable light source and already embodies a versatile and flexible light source for applications, e.g., for smart microscopy.

  5. Heliocentric radial variation of plasma oscillations associated with type III radio bursts

    International Nuclear Information System (INIS)

    Gurnett, D.A.; Anderson, R.R.; Scarf, F.L.; Kurth, W.S.

    1978-01-01

    A survey is presented of all of the electron plasma oscillation events found to date in association with low-frequency type III solar radio bursts using approximately 9 years of observations from the Imp 6 and 8, Helios 1 and 2, and Voyager 1 and 2 spacecraft. Plasma oscillation events associated with type III radio bursts show a pronounced increase in both the intensity and the frequency of occurrence with decreasing heliocentric radial distance. This radial dependence explains why intense electron plasma oscillations are seldom observed in association with type III radio bursts at the orbit of the earth. Possible interpretations of the observed radial variation in the plasma oscillation intensity are considered

  6. Destructive impact of molecular noise on nanoscale electrochemical oscillators

    Science.gov (United States)

    Cosi, Filippo G.; Krischer, Katharina

    2017-06-01

    We study the loss of coherence of electrochemical oscillations on meso- and nanosized electrodes with numeric simulations of the electrochemical master equation for a prototypical electrochemical oscillator, the hydrogen peroxide reduction on Pt electrodes in the presence of halides. On nanoelectrodes, the electrode potential changes whenever a stochastic electron-transfer event takes place. Electrochemical reaction rate coefficients depend exponentially on the electrode potential and become thus fluctuating quantities as well. Therefore, also the transition rates between system states become time-dependent which constitutes a fundamental difference to purely chemical nanoscale oscillators. Three implications are demonstrated: (a) oscillations and steady states shift in phase space with decreasing system size, thereby also decreasing considerably the oscillating parameter regions; (b) the minimal number of molecules necessary to support correlated oscillations is more than 10 times as large as for nanoscale chemical oscillators; (c) the relation between correlation time and variance of the period of the oscillations predicted for chemical oscillators in the weak noise limit is only fulfilled in a very restricted parameter range for the electrochemical nano-oscillator.

  7. Strategic Planning for Electronic Resources Management: A Case Study at Gustavus Adolphus College

    Science.gov (United States)

    Hulseberg, Anna; Monson, Sarah

    2009-01-01

    Electronic resources, the tools we use to manage them, and the needs and expectations of our users are constantly evolving; at the same time, the roles, responsibilities, and workflow of the library staff who manage e-resources are also in flux. Recognizing a need to be more intentional and proactive about how we manage e-resources, the…

  8. REVIEW OF MOODLE PLUGINS FOR DESIGNING MULTIMEDIA ELECTRONIC EDUCATIONAL RESOURCES FROM LANGUAGE DISCIPLINES

    Directory of Open Access Journals (Sweden)

    Anton M. Avramchuk

    2015-09-01

    Full Text Available Today the problem of designing multimedia electronic educational resources from language disciplines in Moodle is very important. This system has a lot of different, powerful resources, plugins to facilitate the learning of students with language disciplines. This article presents an overview and comparative analysis of the five Moodle plugins for designing multimedia electronic educational resources from language disciplines. There have been considered their key features and functionality in order to choose the best for studying language disciplines in the Moodle. Plugins are compared by a group of experts according to the criteria: efficiency, functionality and easy use. For a comparative analysis of the plugins it is used the analytic hierarchy process.

  9. Results and analysis of free-electron-laser oscillation in a high-energy storage ring

    International Nuclear Information System (INIS)

    Couprie, M.E.; Velghe, M.; Prazeres, R.; Jaroszynski, D.; Billardon, M.

    1991-01-01

    A storage-ring free-electron laser at Orsay has been operating since 1989 in the visible wavelength range. In contrast with previous experiments, it operates with positrons and at higher energies (600--800 MeV), with the storage ring Super-ACO (ACO denotes Anneau de Collisions d'Orsay). The optical gain, the laser power, the transverse profile, and the macrotemporal structure of the laser are analyzed. In particular, we show that the gain matrix possesses many off-diagonal elements, which results in lasing on a combination of noncylindrical Gaussian modes. The eigenmode of the laser oscillation is a combination of one or two main Gaussian modes and several higher-order modes, which results in most of the power being extracted in these modes

  10. Climate variability and El Niño Southern Oscillation: implications for natural coastal resources and management

    Science.gov (United States)

    Thatje, Sven; Heilmayer, Olaf; Laudien, Jürgen

    2008-03-01

    The El Niño Southern Oscillation (ENSO) significantly influences marine ecosystems and the sustained exploitation of marine resources in the coastal zone of the Humboldt Current upwelling system. Both its warm (El Niño: EN) and cold (La Niña: LN) phase have drastic implications for the ecology, socio-economy and infrastructure along most of Pacific South America. Local artisanal fisheries, which especially suffer from the effects of EN, represent a major part for the domestic economy of Chile and Peru and in consequence a huge amount of published and unpublished studies exists aiming at identifying effects of EN and LN. However, most processes and underlying mechanisms fostering the ecology of organisms along Pacific South America have not been analyzed yet and for the marine realm most knowledge is traditionally based on rather descriptive approaches. We herein advocate that small-scale comparative and interdisciplinary process studies work as one possible solution to understand better the variability observed in EN/LN effects at local scale. We propose that differences in small-scale impacts of ENSO along the coast rather than the macro-ecological and oceanographic view are essential for the sustainable management of costal ecosystems and the livelihood of the people depending on it. Based on this, we summarize the conceptual approach from the EU-funded International Science and Technology Cooperation (INCO) project “Climate variability and El Niño Southern Oscillation: Implications for Natural Coastal Resources and Management (CENSOR)” that aims at enhancing the detection, compilation, and understanding of EN and LN effects on the coastal zone and its natural resources. We promote a multidisciplinary avenue within present international funding schemes, with the intention to bridge the traditional gap between basic and applied coastal research. The long-term aim is an increased mitigation of harm caused by EN as well as a better use of beneficial effects

  11. Modern ICT Tools: Online Electronic Resources Sharing Using Web ...

    African Journals Online (AJOL)

    Modern ICT Tools: Online Electronic Resources Sharing Using Web 2.0 and Its Implications For Library And Information Practice In Nigeria. ... The PDF file you selected should load here if your Web browser has a PDF reader plug-in installed (for example, a recent version of Adobe Acrobat Reader). If you would like more ...

  12. Neutral current induced neutrino oscillations in a supernova

    CERN Document Server

    Kusenko, A; Kusenko, Alexander; Segre, Gino

    1997-01-01

    Neutral currents induced matter oscillations of electroweak-active (anti-)neutrinos to sterile neutrinos can explain the observed motion of pulsars. In contrast to a recently proposed explanation of the pulsar birth velocities based on the electron to tau (muon) neutrino oscillations [hep-ph/9606428], the heaviest neutrino (either active or sterile) would have to have mass of order several keV.

  13. Coupled Langmuir oscillations in 2-dimensional quantum plasmas

    International Nuclear Information System (INIS)

    Akbari-Moghanjoughi, M.

    2014-01-01

    In this work, we present a hydrodynamic model to study the coupled quantum electron plasma oscillations (QEPO) for two dimensional (2D) degenerate plasmas, which incorporates all the essential quantum ingredients such as the statistical degeneracy pressure, electron-exchange, and electron quantum diffraction effect. Effects of diverse physical aspects like the electronic band-dispersion effect, the electron exchange-correlations and the quantum Bohm-potential as well as other important plasma parameters such as the coupling parameter (plasma separation) and the plasma electron number-densities on the linear response of the coupled system are investigated. By studying three different 2D plasma coupling types, namely, graphene-graphene, graphene-metalfilm, and metalfilm-metalfilm coupling configurations, it is remarked that the collective quantum effects can influence the coupled modes quite differently, depending on the type of the plasma configuration. It is also found that the slow and fast QEPO frequency modes respond very differently to the change in plasma parameters. Current findings can help in understanding of the coupled density oscillations in multilayer graphene, graphene-based heterojunctions, or nanofabricated integrated circuits

  14. Status and oscillation results of the OPERA experiment

    International Nuclear Information System (INIS)

    Brunet, F.

    2014-01-01

    The OPERA experiment, placed 730 km downstream the CERN neutrino beam to Gran Sasso (CNGS) in the LNGS underground laboratory, is designed to measure muon-neutrino to tau-neutrino oscillations in a direct appearance mode. The hybrid apparatus consists of an emulsion/lead target complemented by electronic detectors. Due to the target structure made of thin lead plates, OPERA is able to detect electromagnetic showers, allowing searches for tau electronic decays and for oscillations from muon-neutrino to electron-neutrino. The experimental set-up and associated facilities used to extract data recorded in the emulsion will be described, with the special procedures aimed at locating interaction vertices and detect short decay topologies. OPERA is taking data since 2008. A first nu-tau interaction candidate was already published in 2010. New results with increased statistics will be presented. In particular, an overview of the studies related to electrons will be shown. (author)

  15. Membrane oscillations in the channel of a stationary plasma motor

    International Nuclear Information System (INIS)

    Bugrova, A.I.; Lipatov, A.S.; Morozov, A.I.; Kharchevnikov, V.K.

    1999-01-01

    Results of measuring the ion flux density in the channel of the stationary plasma drive are presented. Two plane easters move both along and transverse to the plasma flux. During the experiment, the strong low-frequency oscillations (∼ 35 kHz) are observed in the channel of the stationary plasma drive. It is found that membrane oscillations are accompanied by oscillations of the electron temperature. These membrane oscillations affect the divergence of the output plasma jet and the erosion of the output part of the channel of the stationary plasma drive [ru

  16. Nonstationary oscillations in gyrotrons revisited

    International Nuclear Information System (INIS)

    Dumbrajs, O.; Kalis, H.

    2015-01-01

    Development of gyrotrons requires careful understanding of different regimes of gyrotron oscillations. It is known that in the planes of the generalized gyrotron variables: cyclotron resonance mismatch and dimensionless current or cyclotron resonance mismatch and dimensionless interaction length complicated alternating sequences of regions of stationary, periodic, automodulation, and chaotic oscillations exist. In the past, these regions were investigated on the supposition that the transit time of electrons through the interaction space is much shorter than the cavity decay time. This assumption is valid for short and/or high diffraction quality resonators. However, in the case of long and/or low diffraction quality resonators, which are often utilized, this assumption is no longer valid. In such a case, a different mathematical formalism has to be used for studying nonstationary oscillations. One example of such a formalism is described in the present paper

  17. THE MODEL OF LINGUISTIC TEACHERS’ COMPETENCY DEVELOPMENT ON DESIGNING MULTIMEDIA ELECTRONIC EDUCATIONAL RESOURCES IN THE MOODLE SYSTEM

    Directory of Open Access Journals (Sweden)

    Anton M. Avramchuk

    2017-10-01

    Full Text Available The article is devoted to the problem of developing the competency of teachers of language disciplines on designing multimedia electronic educational resources in the Moodle system. The concept of "the competence of teachers of language disciplines on designing multimedia electronic educational resources in the Moodle system" is justified and defined. Identified and characterized the components by which the levels of the competency development of teachers of language disciplines on designing multimedia electronic educational resources in the Moodle system should be assessed. Developed a model for the development of the competency of teachers of language disciplines on designing multimedia electronic educational resources in the Moodle system, which is based on the main scientific approaches, used in adult education, and consists of five blocks: target, informative, technological, diagnostic and effective.

  18. Developing Humanities Collections in the Digital Age: Exploring Humanities Faculty Engagement with Electronic and Print Resources

    Science.gov (United States)

    Kachaluba, Sarah Buck; Brady, Jessica Evans; Critten, Jessica

    2014-01-01

    This article is based on quantitative and qualitative research examining humanities scholars' understandings of the advantages and disadvantages of print versus electronic information resources. It explores how humanities' faculty members at Florida State University (FSU) use print and electronic resources, as well as how they perceive these…

  19. Generalized oscillator strengths for the valence-shell excitations of argon

    International Nuclear Information System (INIS)

    Zhu Linfan; Cheng Huadong; Yuan Zhensheng; Liu Xiaojing; Sun Jianmin; Xu Kezun

    2006-01-01

    The generalized oscillator strengths for the valence-shell excitations to 3p 5 (4s,4s ' ) and 3p 5 (4p,4p ' ) of argon were measured by an angle-resolved fast-electron energy-loss spectrometer at an incident electron energy of 2500 eV. The transition multipolarities for these excitations were elucidated with the help of the calculated intermediate coupling coefficients using the COWAN code. The generalized oscillator strength profiles for the electric dipole excitations to 3p 5 (4s,4s ' ), the electric quadrupole and monopole excitations to 3p 5 (4p,4p ' ) were analyzed and their positions of the extrema were determined. Furthermore, the generalized oscillator strength of the electric quadrupole excitation in 3p→4p was determined and its profile is in general agreement with the theoretical calculations. However, the generalized oscillator strength profile of the electric monopole excitation in 3p→4p is different from the theoretical calculations

  20. Asymmetry in Signal Oscillations Contributes to Efficiency of Periodic Systems.

    Science.gov (United States)

    Bae, Seul-A; Acevedo, Alison; Androulakis, Ioannis P

    2016-01-01

    Oscillations are an important feature of cellular signaling that result from complex combinations of positive- and negative-feedback loops. The encoding and decoding mechanisms of oscillations based on amplitude and frequency have been extensively discussed in the literature in the context of intercellular and intracellular signaling. However, the fundamental questions of whether and how oscillatory signals offer any competitive advantages-and, if so, what-have not been fully answered. We investigated established oscillatory mechanisms and designed a study to analyze the oscillatory characteristics of signaling molecules and system output in an effort to answer these questions. Two classic oscillators, Goodwin and PER, were selected as the model systems, and corresponding no-feedback models were created for each oscillator to discover the advantage of oscillating signals. Through simulating the original oscillators and the matching no-feedback models, we show that oscillating systems have the capability to achieve better resource-to-output efficiency, and we identify oscillatory characteristics that lead to improved efficiency.

  1. Optics-free x-ray FEL oscillator

    International Nuclear Information System (INIS)

    Litvinenko, V.N.; Hao, Y.; Kayran, D.; Trbojevic, D.

    2011-01-01

    There is a need for an Optics-Free FEL Oscillators (OFFELO) to further the advantages of free-electron lasers and turning them in fully coherent light sources. While SASE (Self-Amplified Spontaneous Emission) FELs demonstrated the capability of providing very high gain and short pulses of radiation and scalability to the X-ray range, the spectra of SASE FELs remains rather wide (∼0.5%-1%) compared with typical short wavelengths FEL-oscillators (0.01%-0.0003% in OK-4 FEL). Absence of good optics in VUV and X-ray ranges makes traditional oscillator schemes with very high average and peak spectral brightness either very complex or, strictly speaking, impossible. In this paper, we discuss lattice of the X-ray optics-free FEL oscillator and present results of initial computer simulations of the feedback process and the evolution of FEL spectrum in X-ray OFFELO. We also discuss main limiting factors and feasibility of X-ray OFFELO.

  2. Optics-free x-ray FEL oscillator

    Energy Technology Data Exchange (ETDEWEB)

    Litvinenko, V.N.; Hao, Y.; Kayran, D.; Trbojevic, D.

    2011-03-28

    There is a need for an Optics-Free FEL Oscillators (OFFELO) to further the advantages of free-electron lasers and turning them in fully coherent light sources. While SASE (Self-Amplified Spontaneous Emission) FELs demonstrated the capability of providing very high gain and short pulses of radiation and scalability to the X-ray range, the spectra of SASE FELs remains rather wide ({approx}0.5%-1%) compared with typical short wavelengths FEL-oscillators (0.01%-0.0003% in OK-4 FEL). Absence of good optics in VUV and X-ray ranges makes traditional oscillator schemes with very high average and peak spectral brightness either very complex or, strictly speaking, impossible. In this paper, we discuss lattice of the X-ray optics-free FEL oscillator and present results of initial computer simulations of the feedback process and the evolution of FEL spectrum in X-ray OFFELO. We also discuss main limiting factors and feasibility of X-ray OFFELO.

  3. Intrinsic current oscillations in an asymmetric triple-barrier resonant tunnelling diode

    International Nuclear Information System (INIS)

    Wójcik, P; Spisak, B J; Wołoszyn, M; Adamowski, J

    2010-01-01

    The electronic transport characteristics of an asymmetric triple-barrier resonant tunnelling diode are calculated by the time-dependent Wigner–Poisson method. The intrinsic current oscillations are found in two separate bias voltage ranges. The first one is located below the resonant current peak, and the second lies in the negative differential resistance region. We provide the explanation of the current density oscillations in these two separate bias voltage ranges based on the analysis of the self-consistent potential profiles and changes of electron density. We have shown that two different formation mechanisms are responsible for the current density oscillations in these two bias voltage ranges. In the bias voltage range below the resonant current peak in the current–voltage characteristics, the current density oscillations are caused by the coupling between quasi-bound states in the left and right quantum wells. On the other hand, the current density oscillations in the negative differential resistance region result from the coupling between quasi-bound states in the left quantum well and the quantum well formed in the region of the left contact

  4. Simply Adjustable Sinusoidal Oscillator Based on Negative Three-Port Current Conveyors

    Directory of Open Access Journals (Sweden)

    R. Sotner

    2010-09-01

    Full Text Available The paper deals with sinusoidal oscillator employing two controlled second-generation negative-current conveyors and two capacitors. The proposed oscillator has a simple circuit configuration. Electronic (voltage adjusting of the oscillation frequency and condition of oscillation are possible. The presented circuit is verified in PSpice utilizing macro models of commercially available negative current conveyors. The circuit is also verified by experimental measurements. Important characteristics and drawbacks of the proposed circuit and influences of real active elements in the designed circuit are discussed in detail.

  5. Electronic resource management systems a workflow approach

    CERN Document Server

    Anderson, Elsa K

    2014-01-01

    To get to the bottom of a successful approach to Electronic Resource Management (ERM), Anderson interviewed staff at 11 institutions about their ERM implementations. Among her conclusions, presented in this issue of Library Technology Reports, is that grasping the intricacies of your workflow-analyzing each step to reveal the gaps and problems-at the beginning is crucial to selecting and implementing an ERM. Whether the system will be used to fill a gap, aggregate critical data, or replace a tedious manual process, the best solution for your library depends on factors such as your current soft

  6. Effect of temperature oscillation on thermal characteristics of an aluminum thin film

    Science.gov (United States)

    Ali, H.; Yilbas, B. S.

    2014-12-01

    Energy transport in aluminum thin film is examined due to temperature disturbance at the film edge. Thermal separation of electron and lattice systems is considered in the analysis, and temperature variation in each sub-system is formulated. The transient analysis of frequency-dependent and frequency-independent phonon radiative transport incorporating electron-phonon coupling is carried out in the thin film. The dispersion relations of aluminum are used in the frequency-dependent analysis. Temperature at one edge of the film is oscillated at various frequencies, and temporal response of phonon intensity distribution in the film is predicted numerically using the discrete ordinate method. To assess the phonon transport characteristics, equivalent equilibrium temperature is introduced. It is found that equivalent equilibrium temperature in the electron and lattice sub-systems oscillates due to temperature oscillation at the film edge. The amplitude of temperature oscillation reduces as the distance along the film thickness increases toward the low-temperature edge of the film. Equivalent equilibrium temperature attains lower values for the frequency-dependent solution of the phonon transport equation than that corresponding to frequency-independent solution.

  7. Electronic Resource Management System. Vernetzung von Lizenzinformationen

    Directory of Open Access Journals (Sweden)

    Michaela Selbach

    2014-12-01

    Full Text Available In den letzten zehn Jahren spielen elektronische Ressourcen im Bereich der Erwerbung eine zunehmend wichtige Rolle: Eindeutig lässt sich hier ein Wandel in den Bibliotheken (fort vom reinen Printbestand zu immer größeren E-Only-Beständen feststellen. Die stetig wachsende Menge an E-Ressourcen und deren Heterogenität stellt Bibliotheken vor die Herausforderung, die E-Ressourcen effizient zu verwalten. Nicht nur Bibliotheken, sondern auch verhandlungsführende Institutionen von Konsortial- und Allianzlizenzen benötigen ein geeignetes Instrument zur Verwaltung von Lizenzinformationen, welches den komplexen Anforderungen moderner E-Ressourcen gerecht wird. Die Deutsche Forschungsgemeinschaft (DFG unterstützt ein Projekt des Hochschulbibliothekszentrums des Landes Nordrhein-Westfalen (hbz, der Universitätsbibliothek Freiburg, der Verbundzentrale des Gemeinsamen Bibliotheksverbundes (GBV und der Universitätsbibliothek Frankfurt, in dem ein bundesweit verfügbares Electronic Ressource Managementsystem (ERMS aufgebaut werden soll. Ein solches ERMS soll auf Basis einer zentralen Knowledge Base eine einheitliche Nutzung von Daten zur Lizenzverwaltung elektronischer Ressourcen auf lokaler, regionaler und nationaler Ebene ermöglichen. Statistische Auswertungen, Rechteverwaltung für alle angeschlossenen Bibliotheken, kooperative Datenpflege sowie ein über standardisierte Schnittstellen geführter Datenaustausch stehen bei der Erarbeitung der Anforderungen ebenso im Fokus wie die Entwicklung eines Daten- und Funktionsmodells. In the last few years the importance of electronic resources in library acquisitions has increased significantly. There has been a shift from mere print holdings to both e- and print combinations and even e-only subscriptions. This shift poses a double challenge for libraries: On the one hand they have to provide their e-resource collections to library users in an appealing way, on the other hand they have to manage these

  8. Two Kinds of Self-Oscillating Circuits Mechanically Demonstrated

    OpenAIRE

    Shiang-Hwua Yu; Po-Hsun Wu

    2015-01-01

    This study introduces two types of self-oscillating circuits that are frequently found in power electronics applications. Special effort is made to relate the circuits to the analogous mechanical systems of some important scientific inventions: Galileo’s pendulum clock and Coulomb’s friction model. A little touch of related history and philosophy of science will hopefully encourage curiosity, advance the understanding of self-oscillating systems and satisfy the aspiration ...

  9. The Electron Microscopy Outreach Program: A Web-based resource for research and education.

    Science.gov (United States)

    Sosinsky, G E; Baker, T S; Hand, G; Ellisman, M H

    1999-01-01

    We have developed a centralized World Wide Web (WWW)-based environment that serves as a resource of software tools and expertise for biological electron microscopy. A major focus is molecular electron microscopy, but the site also includes information and links on structural biology at all levels of resolution. This site serves to help integrate or link structural biology techniques in accordance with user needs. The WWW site, called the Electron Microscopy (EM) Outreach Program (URL: http://emoutreach.sdsc.edu), provides scientists with computational and educational tools for their research and edification. In particular, we have set up a centralized resource containing course notes, references, and links to image analysis and three-dimensional reconstruction software for investigators wanting to learn about EM techniques either within or outside of their fields of expertise. Copyright 1999 Academic Press.

  10. Technical Communicator: A New Model for the Electronic Resources Librarian?

    Science.gov (United States)

    Hulseberg, Anna

    2016-01-01

    This article explores whether technical communicator is a useful model for electronic resources (ER) librarians. The fields of ER librarianship and technical communication (TC) originated and continue to develop in relation to evolving technologies. A review of the literature reveals four common themes for ER librarianship and TC. While the…

  11. Reflector development for XUV free-electron laser oscillators

    International Nuclear Information System (INIS)

    Newnam, B.E.

    1992-01-01

    The potential for extending FEL oscillators into the extreme ultraviolet below 100 nm has stimulated new resonator mirror concepts and experimental studies of promising reflective materials. Degradation of mirror reflectance by oxide and carbonaceous contaminants can be controlled by proper vacuum environment plus in situ cleaning, and periodic surface renewal. Multifacet mirrors within ring resonators will provide the desired broad-band reflectance and limit beam-induced thermal distortion to a tolerable level. 27 refs

  12. Anomalous normal mode oscillations in semiconductor microcavities

    Energy Technology Data Exchange (ETDEWEB)

    Wang, H. [Univ. of Oregon, Eugene, OR (United States). Dept. of Physics; Hou, H.Q.; Hammons, B.E. [Sandia National Labs., Albuquerque, NM (United States)

    1997-04-01

    Semiconductor microcavities as a composite exciton-cavity system can be characterized by two normal modes. Under an impulsive excitation by a short laser pulse, optical polarizations associated with the two normal modes have a {pi} phase difference. The total induced optical polarization is then expected to exhibit a sin{sup 2}({Omega}t)-like oscillation where 2{Omega} is the normal mode splitting, reflecting a coherent energy exchange between the exciton and cavity. In this paper the authors present experimental studies of normal mode oscillations using three-pulse transient four wave mixing (FWM). The result reveals surprisingly that when the cavity is tuned far below the exciton resonance, normal mode oscillation in the polarization is cos{sup 2}({Omega}t)-like, in contrast to what is expected form the simple normal mode model. This anomalous normal mode oscillation reflects the important role of virtual excitation of electronic states in semiconductor microcavities.

  13. A memristor-based third-order oscillator: beyond oscillation

    KAUST Repository

    Talukdar, Abdul Hafiz Ibne

    2012-10-06

    This paper demonstrates the first third-order autonomous linear time variant circuit realization that enhances parametric oscillation through the usage of memristor in conventional oscillators. Although the output has sustained oscillation, the linear features of the conventional oscillators become time dependent. The poles oscillate in nonlinear behavior due to the oscillation of memristor resistance. The mathematical formulas as well as SPICE simulations are introduced for the memristor-based phase shift oscillator showing a great matching.

  14. A memristor-based third-order oscillator: beyond oscillation

    KAUST Repository

    Talukdar, Abdul Hafiz Ibne; Radwan, Ahmed G.; Salama, Khaled N.

    2012-01-01

    This paper demonstrates the first third-order autonomous linear time variant circuit realization that enhances parametric oscillation through the usage of memristor in conventional oscillators. Although the output has sustained oscillation, the linear features of the conventional oscillators become time dependent. The poles oscillate in nonlinear behavior due to the oscillation of memristor resistance. The mathematical formulas as well as SPICE simulations are introduced for the memristor-based phase shift oscillator showing a great matching.

  15. Potential and electron density calculated for freely expanding plasma by an electron beam

    International Nuclear Information System (INIS)

    Ho, C. Y.; Tsai, Y. H.; Ma, C.; Wen, M. Y.

    2011-01-01

    This paper investigates the radial distributions of potential and electron density in free expansion plasma induced by an electron beam irradiating on the plate. The region of plasma production is assumed to be cylindrical, and the plasma expansion is assumed to be from a cylindrical source. Therefore, the one-dimensional model in cylindrical coordinates is employed in order to analyze the radial distributions of the potential and electron density. The Runge-Kutta method and the perturbation method are utilized in order to obtain the numerical and approximate solutions, respectively. The results reveal that the decrease in the initial ion energy makes most of the ions gather near the plasma production region and reduces the distribution of the average positive potential, electron, and ion density along the radial direction. The oscillation of steady-state plasma along the radial direction is also presented in this paper. The ions induce a larger amplitude of oscillation along the radial direction than do electrons because the electrons oscillate around slowly moving ions due to a far smaller electron mass than ion mass. The radial distributions of the positive potential and electron density predicted from this study are compared with the available experimental data.

  16. Periodic Forcing of a 555-IC Based Electronic Oscillator in the Strong Coupling Limit

    Science.gov (United States)

    Santillán, Moisés

    We designed and developed a master-slave electronic oscillatory system (based on the 555-timer IC working in the astable mode), and investigated its dynamic behavior regarding synchronization. For that purpose, we measured the rotation numbers corresponding to the phase-locking rhythms achieved in a large set of values of the normalized forcing frequency (NFF) and of the coupling strength between the master and the slave oscillators. In particular, we were interested in the system behavior in the strong-coupling limit, because such problem has not been extensively studied from an experimental perspective. Our results indicate that, in such a limit, a degenerate codimension-2 bifurcation point at NFF = 2 exists, in which all the phase-locking regions converge. These findings were corroborated by means of a mathematical model developed to that end, as well as by ad hoc further experiments.

  17. Parametric excitation of nonlinear longitudinal oscillations in a magnetoactive plasma

    International Nuclear Information System (INIS)

    Demchenko, V.V.

    1977-01-01

    Parametric excitation by HF field of nonlinear longitudinal electron oscillations in the region of hybrid resonances of a cold nonrelativistic plasma has been investigated. It is shown that the inhomogeneity of a pumping field and that of the equilibrium plasma density result in the parametric instability. Expressions are derived for the increments of instable oscillations and the widths of the instability regions are determined. The increments of instable oscillations in the order of magnitude due to the inhomogeneities of the pumping field (γsub(E)) or of the plasma density (γsub(N)) are egual to γsub(E) approximately k(zetasub(0)) ωsub(pe), γsub(N) approximately (zetasub(0))/Lωsub(pe), where (zetasub(0))=(e)Esub(0)/msub(e)ωsub(0)sup(2) is the amplitude of displacement of an electron from the equilibrium state, k, ω 0 , E 0 are the wave number, frequency and amplitude of the pumping field, L is the characteristic size of the inhomogeneity of the plasma density, ωsub(pe) is the electron plasma frequency

  18. A WORK-NOTE on OSCILLATORS - LEARNING by DOING

    DEFF Research Database (Denmark)

    Lindberg, Erik

    2005-01-01

    The aim of this work-note is to give insight in computer aided design of electronic oscillators by means of a study of a number of circuits given as figures - equivalent schemes - or as net-list files for electronic circuit analysis programs - "SPICE FILES". For each figure or net-list a number...

  19. MODEL OF AN ELECTRONIC EDUCATIONAL RESOURCE OF NEW GENERATION

    Directory of Open Access Journals (Sweden)

    Anatoliy V. Loban

    2016-01-01

    Full Text Available The mathematical structure of the modular architecture of an electronic educational resource (EER of new generation, which allows to decompose the process of studying the subjects of the course at a hierarchically ordered set of data (knowledge and procedures for manipulating them, to determine the roles of participants of process of training of and technology the development and use of EOR in the study procrate.

  20. Soft Dielectric Elastomer Oscillators Driving Bioinspired Robots.

    Science.gov (United States)

    Henke, E-F Markus; Schlatter, Samuel; Anderson, Iain A

    2017-12-01

    Entirely soft robots with animal-like behavior and integrated artificial nervous systems will open up totally new perspectives and applications. To produce them, we must integrate control and actuation in the same soft structure. Soft actuators (e.g., pneumatic and hydraulic) exist but electronics are hard and stiff and remotely located. We present novel soft, electronics-free dielectric elastomer oscillators, which are able to drive bioinspired robots. As a demonstrator, we present a robot that mimics the crawling motion of the caterpillar, with an integrated artificial nervous system, soft actuators and without any conventional stiff electronic parts. Supplied with an external DC voltage, the robot autonomously generates all signals that are necessary to drive its dielectric elastomer actuators, and it translates an in-plane electromechanical oscillation into a crawling locomotion movement. Therefore, all functional and supporting parts are made of polymer materials and carbon. Besides the basic design of this first electronic-free, biomimetic robot, we present prospects to control the general behavior of such robots. The absence of conventional stiff electronics and the exclusive use of polymeric materials will provide a large step toward real animal-like robots, compliant human machine interfaces, and a new class of distributed, neuron-like internal control for robotic systems.

  1. Terahertz quantum cascade laser as local oscillator in a heterodyne receiver.

    Science.gov (United States)

    Hübers, Heinz-Wilhelm; Pavlov, S; Semenov, A; Köhler, R; Mahler, L; Tredicucci, A; Beere, H; Ritchie, D; Linfield, E

    2005-07-25

    Terahertz quantum cascade lasers have been investigated with respect to their performance as a local oscillator in a heterodyne receiver. The beam profile has been measured and transformed in to a close to Gaussian profile resulting in a good matching between the field patterns of the quantum cascade laser and the antenna of a superconducting hot electron bolometric mixer. Noise temperature measurements with the hot electron bolometer and a 2.5 THz quantum cascade laser yielded the same result as with a gas laser as local oscillator.

  2. Absolute generalized oscillator strength for the Lyman--Birge--Hopfield band of N2 as determined by high energy electron impact spectroscopy

    International Nuclear Information System (INIS)

    Wong, T.C.; Lee, J.S.; Wellenstein, H.F.; Bonham, R.A.

    1975-01-01

    The absolute generalized oscillator strength for the dipole forbidden quadrupole allowed Lyman--Birge--Hopfield band a 1 Pi/subg/ reverse arrow X 1 Σ + /subg/ in molecular nitrogen at an energy loss of 9.35 eV is observed by electron impact spectroscopy using 25 keV electrons over the momentum transfer range 0.04less than or equal toK 2 less than or equal to10 a.u. The results agree in the zero angle (zero momentum transfer) limit with the previous observations of Skerbele and Lassettre, but are in disagreement with previous theoretical and experimental results for K 2 >0.5. (auth)

  3. Oscillations of the static meson fields at finite baryon density

    International Nuclear Information System (INIS)

    Florkowski, W.; Friman, B.; Technische Hochschule Darmstadt

    1996-04-01

    The spatial dependence of static meson correlation functions at finite baryon density is studied in the Nambu-Jona-Lasinio model. In contrast to the finite temperature case, we find that the correlation functions at finite density are not screened but exhibit long-range oscillations. The observed phenomenon is analogous to the Friedel oscillations in a degenerate electron gas. (orig.)

  4. Investigation of 0.38 THz backward-wave oscillator based on slotted sine waveguide and pencil electron beam

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Luqi; Wei, Yanyu; Wang, Bing; Shen, Wenan; Xu, Jin; Gong, Yubin [National Key Laboratory of Science and Technology on Vacuum Electronics, School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054 (China); Park, Gun-Sik [The Department of Physics and Astronomy, Seoul National University, Seoul 151-747 (Korea, Republic of)

    2016-03-15

    A novel backward wave oscillator (BWO) is presented by utilizing a slotted sine waveguide with a pencil electron beam to produce the high power terahertz wave. The high frequency characteristics including dispersion properties, interaction impedances, and transmission characteristics of the slotted sine waveguide are analyzed in detail. The high frequency system including the output coupler, slow wave structure (SWS), and reflector are designed properly. A 3-D particle-in-cell mode is applied to predict the device performance of the BWO based on the novel SWS. The investigation results demonstrate that this device can generate over 8.05 W output power in the frequency range of 363.4–383.8 GHz by using a 30 mA pencil electron beam and adjusting the beam voltage from 20 kV to 32 kV.

  5. Emission of SNF-oscillations by the plasma - periodic decelerating structure system

    International Nuclear Information System (INIS)

    Antonov, A.N.; Gestrina, G.N.; Kovpik, O.F.; Kornilov, E.A.; Moiseev, S.S.

    1983-01-01

    Emission of SHF-oscillations by a magnetoactive plasma inside a decelerating structure (annular waveguide), which is excited by an electron beam, has been studied. The electron beam is formed by a diode electron gun. Pulse duration was 400 μs, beam energy = 10 keV, current - up to 5 A. The beam 1.8 cm in diameter is injected into a glass interaction chamber. The chamber diameter is 20 cm, the length is 1 m. The interaction chamber and electron gun chamber were placed in a homogeneous magnetic field with intensity up to 2.5x10 5 axm -1 . The periodic deceleration structure was located in the interaction chamber coaxially with the electron beam. The structure total length was 40 cm. The working gas, argon, was fed into the structure through a needle injector. It is shown that the three-dimensional waves appearing in the plasma can be transformed by the structure to those emited without plasma density gradients and magnetic field. Conditions of effective separation of the energy of SHF-oscillations from the system: plasm-beam-narrow-slit decelerating structure are found. The above system can be used for amplification and generation of monochromatic oscillations in the millimeter waves range. Results of experimental studies are compared with theoretical calculations

  6. Observation of superradiance in a short-pulse FEL oscillator

    NARCIS (Netherlands)

    Jaroszynski, D. A.; Chaix, P.; Piovella, N.; Oepts, D.; Knippels, G.M.H.; van der Meer, A. F. G.; Weits, H. H.

    1997-01-01

    Superradiance has been experimentally studied, in a short-pulse free-electron laser (FEL) oscillator. Superradiance is the optimal way of extracting optical radiation from an FEL and can be characterised by the following scale laws: peak optical power P, scales as the square of electron charge, Q,

  7. Behaviour of Bichromatic Microwave Induced Magnetoresistance Oscillations in the High Mobility GaAs/AlGaAs 2D electron System

    International Nuclear Information System (INIS)

    Gunawardana, Binuka; Liu, Han-Chun; Samaraweera, Rasanga L.; Mani, R.G.; Reichl, C.; Wegscheider, W

    2017-01-01

    Microwave radiation-induced magneto-resistance oscillations are examined under bichromatic excitation for various frequency combinations in order to obtain a better understanding of the lineshape observed in the dual excitation experiment of the high mobility GaAs/AlGaAs 2D electron system. Here, we examine superposition- or lack thereof- in the lineshape observed in the bichromatic experiment, and report a trend observed between the monochromatic and bichromatic responses of the oscillatory diagonal resistance. (paper)

  8. Improvement of the low frequency oscillation model for Hall thrusters

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Chunsheng, E-mail: wangcs@hit.edu.cn; Wang, Huashan [Yanshan University, College of Vehicles and Energy, Qinhuangdao 066004, Hebei (China)

    2016-08-15

    The low frequency oscillation of the discharge current in Hall thrusters is a major aspect of these devices that requires further study. While the existing model captures the ionization mechanism of the low frequency oscillation, it unfortunately fails to express the dynamic characteristics of the ion acceleration. The analysis in this paper shows this is because of the simplification of the electron equation, which affects both the electric field distribution and the ion acceleration process. Additionally, the electron density equation is revised and a new model that is based on the physical properties of ion movement is proposed.

  9. Density Profiles, Energy, and Oscillation Strength of a Quantum Dot in Two Dimensions with a Harmonic Oscillator External Potential using an Orbital-free Energy Functional Based on Thomas–Fermi Theory

    Directory of Open Access Journals (Sweden)

    Suhufa Alfarisa

    2016-03-01

    Full Text Available This research aims i to determine the density profile and calculate the ground state energy of a quantum dot in two dimensions (2D with a harmonic oscillator potential using orbital-free density functional theory, and ii to understand the effect of the harmonic oscillator potential strength on the electron density profiles in the quantum dot. This study determines the total energy functional of the quantum dot that is a functional of the density that depends only on spatial variables. The total energy functional consists of three terms. The first term is the kinetic energy functional, which is the Thomas–Fermi approximation in this case. The second term is the external potential. The harmonic oscillator potential is used in this study. The last term is the electron–electron interactions described by the Coulomb interaction. The functional is formally solved to obtain the electron density as a function of spatial variables. This equation cannot be solved analytically, and thus a numerical method is used to determine the profile of the electron density. Using the electron density profiles, the ground state energy of the quantum dot in 2D can be calculated. The ground state energies obtained are 2.464, 22.26, 90.1957, 252.437, and 496.658 au for 2, 6, 12, 20, and 56 electrons, respectively. The highest electron density is localized close to the middle of the quantum dot. The density profiles decrease with the increasing distance, and the lowest density is at the edge of the quantum dot. Generally, increasing the harmonic oscillator potential strength reduces the density profiles around the center of the quantum dot.

  10. XUV/VUV free-electron laser oscillator

    International Nuclear Information System (INIS)

    Goldstein, J.C.; Newnam, B.E.; Cooper, R.K.; Comly, J.C. Jr.

    1984-04-01

    It is shown, from computations based on a detailed theoretical model, that modest improvements in electron beam and optical mirror technologies will enable a free-electron laser, driven by an rf linear accelerator, to operate in the 50 to 200-nm range of optical wavelengths. 10 references

  11. Oscillations of the static meson fields at finite baryon density

    International Nuclear Information System (INIS)

    Florkowski, W.; Friman, B.; Technische Hochschule Darmstadt

    1996-04-01

    The spatial dependence of static meson correlation functions at finite baryon density is studied in the Nambu-Jona-Lasinio model. In contrast to the finite temperature case, we find that the correlation functions at finite density are not screened but exhibit long-range oscillations. The observed phenomenon is analogous to the Friedel oscillations in a degenerate electron gas. (author). 19 refs, 6 figs

  12. Measurement of atmospheric neutrino oscillations and matter effects with PINGU

    Energy Technology Data Exchange (ETDEWEB)

    Coenders, Stefan; Euler, Sebastian; Krings, Kai; Vehring, Markus; Wallraff, Marius; Wiebusch, Christopher [RWTH Aachen Univ. (Germany). III. Physikalisches Inst.; Collaboration: IceCube-Collaboration

    2013-07-01

    With IceCube's low-energy extension DeepCore the first significant effects of atmospheric neutrino oscillations have been observed. The planned ''Precision Icecube Next Generation Upgrade'' (PINGU) inside DeepCore will lower the energy threshold to a few GeV, where matter effects of neutrino oscillations have to be taken into account. The Mikheyev-Smirnov-Wolfenstein (MSW) effect modifies the mixing between flavor and mass eigenstates of the neutrinos, resulting in stronger oscillations. Furthermore, neutrinos when passing through the Earth core experience parametric enhancement due to multiple discontinuities in the electron density. In this talk the effects of matter oscillations and the capabilities to measure these effects with PINGU are investigated.

  13. Bunching phase evolution of short-pulse FEL oscillator system

    CERN Document Server

    Song, S B; Choi, D I

    2000-01-01

    We studied numerically the short-pulse FEL oscillator system using properly defined bunching phase theta sub B and PSI sub B. In stable operation, we have found that the optical field 'locks' the phase to pi/2 at the trailing edge, which gives the maximum gain. Moreover, electrons can be detrapped from ponderomotive bucket due to the spatial variation of the optical field, and this detrapping effect is a major cause of the limit cycle oscillation of the system. The 'bump' of the output power during the amplification usually exists at the near-perfect cavity synchronism regime, which can be explained as the change of the matching condition between electron micropulse and optical pulse.

  14. Multidecadal oscillations in rainfall and hydrological extremes

    Science.gov (United States)

    Willems, Patrick

    2013-04-01

    Many studies have anticipated a worldwide increase in the frequency and intensity of precipitation extremes and floods since the last decade(s). Natural variability by climate oscillations partly determines the observed evolution of precipitation extremes. Based on a technique for the identification and analysis of changes in extreme quantiles, it is shown that hydrological extremes have oscillatory behaviour at multidecadal time scales. Results are based on nearly independent extremes extracted from long-term historical time series of precipitation intensities and river flows. Study regions include Belgium - The Netherlands (Meuse basin), Ethiopia (Blue Nile basin) and Ecuador (Paute basin). For Belgium - The Netherlands, the past 100 years showed larger and more hydrological extremes around the 1910s, 1950-1960s, and more recently during the 1990-2000s. Interestingly, the oscillations for southwestern Europe are anti-correlated with these of northwestern Europe, thus with oscillation highs in the 1930-1940s and 1970s. The precipitation oscillation peaks are explained by persistence in atmospheric circulation patterns over the North Atlantic during periods of 10 to 15 years. References: Ntegeka V., Willems P. (2008), 'Trends and multidecadal oscillations in rainfall extremes, based on a more than 100 years time series of 10 minutes rainfall intensities at Uccle, Belgium', Water Resources Research, 44, W07402, doi:10.1029/2007WR006471 Mora, D., Willems, P. (2012), 'Decadal oscillations in rainfall and air temperature in the Paute River Basin - Southern Andes of Ecuador', Theoretical and Applied Climatology, 108(1), 267-282, doi:0.1007/s00704-011-0527-4 Taye, M.T., Willems, P. (2011). 'Influence of climate variability on representative QDF predictions of the upper Blue Nile Basin', Journal of Hydrology, 411, 355-365, doi:10.1016/j.jhydrol.2011.10.019 Taye, M.T., Willems, P. (2012). 'Temporal variability of hydro-climatic extremes in the Blue Nile basin', Water

  15. Generation of “gigantic” ultra-short microwave pulses based on passive mode-locking effect in electron oscillators with saturable absorber in the feedback loop

    International Nuclear Information System (INIS)

    Ginzburg, N. S.; Denisov, G. G.; Vilkov, M. N.; Zotova, I. V.; Sergeev, A. S.

    2016-01-01

    A periodic train of powerful ultrashort microwave pulses can be generated in electron oscillators with a non-linear saturable absorber installed in the feedback loop. This method of pulse formation resembles the passive mode-locking widely used in laser physics. Nevertheless, there is a specific feature in the mechanism of pulse amplification when consecutive energy extraction from different fractions of a stationary electron beam takes place due to pulse slippage over the beam caused by the difference between the wave group velocity and the electron axial velocity. As a result, the peak power of generated “gigantic” pulses can exceed not only the level of steady-state generation but also, in the optimal case, the power of the driving electron beam.

  16. Classical plasma dynamics of Mie-oscillations in atomic clusters

    Science.gov (United States)

    Kull, H.-J.; El-Khawaldeh, A.

    2018-04-01

    Mie plasmons are of basic importance for the absorption of laser light by atomic clusters. In this work we first review the classical Rayleigh-theory of a dielectric sphere in an external electric field and Thomson’s plum-pudding model applied to atomic clusters. Both approaches allow for elementary discussions of Mie oscillations, however, they also indicate deficiencies in describing the damping mechanisms by electrons crossing the cluster surface. Nonlinear oscillator models have been widely studied to gain an understanding of damping and absorption by outer ionization of the cluster. In the present work, we attempt to address the issue of plasmon relaxation in atomic clusters in more detail based on classical particle simulations. In particular, we wish to study the role of thermal motion on plasmon relaxation, thereby extending nonlinear models of collective single-electron motion. Our simulations are particularly adopted to the regime of classical kinetics in weakly coupled plasmas and to cluster sizes extending the Debye-screening length. It will be illustrated how surface scattering leads to the relaxation of Mie oscillations in the presence of thermal motion and of electron spill-out at the cluster surface. This work is intended to give, from a classical perspective, further insight into recent work on plasmon relaxation in quantum plasmas [1].

  17. Generalized oscillator strengths for some higher valence-shell excitations of argon

    International Nuclear Information System (INIS)

    Zhu, Lin-Fan; Yuan, Hui; Jiang, Wei-Chun; Zhang, Fang-Xin; Yuan, Zhen-Sheng; Cheng, Hua-Dong; Xu, Ke-Zun

    2007-01-01

    The valence shell excitations of argon were investigated by an angle-resolved fast-electron energy-loss spectrometer at an incident electron energy of 2500 eV, and the transition multipolarities for the excitations of 3p→3d, 4d, 5s, and 5p were elucidated with the help of the calculated intermediate coupling coefficients using the COWAN code. The generalized oscillator strengths for the excitations to 3p 5 (3d,3d ' ), 3p 5 (5p,5p ' ), and 3p 5 (5s,4d) were measured, and the profiles of these generalized oscillator strength were analyzed. Furthermore, although the present experimental positions of the maxima for the electric-monopole and electric-quadrupole excitations in 3p→5p are in agreement with the theoretical calculations [Amusia et al., Phys. Rev. A 67, 022703 (2003)], the generalized oscillator strength profiles show obvious differences. In addition, the experimental generalized oscillator strength ratios for the electric-octupole transitions in 3p→3d are different from the theoretical prediction calculated by the COWAN code

  18. Self-sustained oscillations in nanoelectromechanical systems induced by Kondo resonance

    International Nuclear Information System (INIS)

    Song, Taegeun; Kiselev, Mikhail N; Kikoin, Konstantin; Shekhter, Robert I; Gorelik, Leonid Y

    2014-01-01

    We investigate the instability and dynamical properties of nanoelectromechanical systems represented by a single-electron device containing movable quantum dots attached to a vibrating cantilever via asymmetric tunnel contacts. The Kondo resonance in electron tunneling between the source and shuttle facilitates self-sustained oscillations originating from the strong coupling of mechanical and electronic/spin degrees of freedom. We analyze a stability diagram for the two-channel Kondo shuttling regime due to limitations given by the electromotive force acting on a moving shuttle, and find that the saturation oscillation amplitude is associated with the retardation effect of the Kondo cloud. The results shed light on possible ways to experimentally realize the Kondo-cloud dynamical probe by using high mechanical dissipation tunability as well as supersensitive detection of mechanical displacement

  19. Self-sustained oscillations in nanoelectromechanical systems induced by Kondo resonance

    Science.gov (United States)

    Song, Taegeun; Kiselev, Mikhail N.; Kikoin, Konstantin; Shekhter, Robert I.; Gorelik, Leonid Y.

    2014-03-01

    We investigate the instability and dynamical properties of nanoelectromechanical systems represented by a single-electron device containing movable quantum dots attached to a vibrating cantilever via asymmetric tunnel contacts. The Kondo resonance in electron tunneling between the source and shuttle facilitates self-sustained oscillations originating from the strong coupling of mechanical and electronic/spin degrees of freedom. We analyze a stability diagram for the two-channel Kondo shuttling regime due to limitations given by the electromotive force acting on a moving shuttle, and find that the saturation oscillation amplitude is associated with the retardation effect of the Kondo cloud. The results shed light on possible ways to experimentally realize the Kondo-cloud dynamical probe by using high mechanical dissipation tunability as well as supersensitive detection of mechanical displacement.

  20. Multi-photon Rabi oscillations in high spin paramagnetic impurity

    International Nuclear Information System (INIS)

    Bertaina, S; Groll, N; Chen, L; Chiorescu, I

    2011-01-01

    We report on multiple photon monochromatic quantum oscillations (Rabi oscillations) observed by pulsed EPR (Electron Paramagnetic Resonance) of Mn 2+ (S = 5/2) impurities in MgO. We find that when the microwave magnetic field is similar or large than the anisotropy splitting, the Rabi oscillations have a spectrum made of many frequencies not predicted by the S = l/2 Rabi model. We show that these new frequencies come from multiple photon coherent manipulation of the multi-level spin impurity. We develop a model based on the crystal field theory and the rotating frame approximation, describing the observed phenomenon with a very good agreement.

  1. Oscillator phenomena in the solar atmosphere and radiation modulation in microwaves

    International Nuclear Information System (INIS)

    Vaz, A.M.Z.

    1983-05-01

    An overview of the principal known descriptions of oscillations in the solar atmosphere at different ranges of periods was developed. Particular attention was given to oscillations with time scale of seconds, associated to active regions or bursts. 1.5 quasi-periodic oscillations were detected by the first time at more than one microwave frequency simultaneously (22 GHz and 44 GHz), with high sensitivity and high time resolution, superimposed on a burst on Dec. 15, 1980. An advance phase of 0,3s between the oscillations in the frequencies of 22 GHz and 44 GHz was discovered. The proposed mechanism to explain such oscillations is based on oscillations of the magnetic field at the source. These oscillations modulate the gyro-synchrotron emission from high energy electrons trapped in the magnetic structure. The phase difference is attributed to the influence of the optical thickness of the gyro-synchrotron emission at 22 GHz. (Author) [pt

  2. Time-Dependent Simulation of Free-Electron Laser Amplifiers and Oscillators

    CERN Document Server

    Freund, H

    2005-01-01

    Time-dependent FEL simulations use a variety of techniques. Most simulations use a slowly varying envelope approximation (SVEA). One such technique assumes that the envelope varies only in z combined with a field representation as an ensemble of discrete harmonics, which is equivalent to a time-dependent simulation [1] but is computationally prohibitive. A second technique uses an SVEA in both in z and t [2]. The particles and fields are advanced in z using the same process as in steady-state simulations and then the time derivative describing slippage is applied. This is used in wiggler-averaged codes such as GINGER [3] and GENESIS [4]. We describe the inclusion of this technique in the non-wiggler-averaged code MEDUSA [5], which is applied to amplifiers and oscillators. MEDUSA differs from GINGER and GENESIS also in the way the field is treated. GINGER and GENESIS use a field solver and must explicitly propagate the field outside the wiggler oscillators. This is computationally intensive. MEDUSA uses a Gaus...

  3. Three-dimensional analysis of nonlinear plasma oscillation

    International Nuclear Information System (INIS)

    Miano, G.

    1990-01-01

    In an underdense plasma a large-amplitude plasma oscillation may be produced by the beating of two external and colinear electromagnetic waves with a frequency difference approximately equal to the plasma frequency - plasma beat wave (PBW) resonant mechanism. The plasma oscillations are driven by the ponderomotive force arising from the beating of the two imposed electromagnetic waves. In this paper two pump electromagnetic waves with arbitrary transverse profiles have been considered. The plasma is described by using the three dimensinal weakly relativistic fluid equations. The nonlinear plasma oscillation dynamics is studied by using the eulerian description, the averaging and the multiple time scale methods. Unlike the linear theory a strong cross field coupling between longitudinal ans transverse electric field components of the plasma oscillation comes out, resulting in a nonlinear phase change and energy transfer between the two components. Unlike the one-dimensional nonlinear theory, the nonlinear frequency shift is caused by relativistic effects as well as by convective effects and electromagnetic field generated from the three dimensional plasma oscillation. The large amplitude plasma oscillation dynamics produced by a bunched relativistic electron beam with arbitrary transverse profile - plasma wave field (PWF) - or by a high power single frequency short electromagnetic pulse with arbitrary transverse profile - electromagnetic plasma wake field (EPWF) - may be described by means of the present theory. (orig.)

  4. Electronic excitation of Na atom by electron impact

    International Nuclear Information System (INIS)

    Bielschowsky, C.E.; Souza, G.G.B. de; Lucas, C.A.; Nogueira, J.C.

    1988-01-01

    Electronic excitation of the 3s-3p transition in the Na atom was studied by intermediate energy electron impact spectroscopy. Differential Cross Sections (DCS) and Generalized Oscillator Strenghts (GOS) were determined experimentally for 1 KeV electrons. Theoretical results within the First Born Approximation as well as Glauber theory, were also performed. (A.C.A.S.) [pt

  5. FEL-Oscillator simulations with Genesis 1.3

    NARCIS (Netherlands)

    Karssenberg, J.G.; van der Slot, Petrus J.M.; Verschuur, Jeroen W.J.; Volokhine, I.; Boller, Klaus J.

    2006-01-01

    Modeling free-electron laser (FEL) oscillators requires calculation of both the light-beam interaction within the undulator and the propagation of the light outside the undulator. We present a paraxial Optical Propagation Code (OPC) based on the Spectral Method and Fresnel Diffraction Integral,

  6. Enhancement of the output power of terahertz folded waveguide oscillator by two parallel electron beams

    International Nuclear Information System (INIS)

    Li, Ke; Cao, Miaomiao; Liu, Wenxin; Wang, Yong; Liao, Suying

    2015-01-01

    A novel two-beam folded waveguide (FW) oscillator is presented for the purpose of gaining higher power with a small-size circuit compared with the normal FW oscillator. The high-frequency characteristics of the two-beam FW, including dispersion and interaction impedance, were investigated by the numerical simulation and compared with the one-beam FW. The radio-frequency loss of the two-beam FW was also analyzed. A 3-D particle-in-cell code CHIPIC was applied to analyze and optimize the performance of a G-band two-beam FW oscillator. The influences of the distance between the two beam tunnels, beam voltage, the number of periods, magnetic field, radius of beam tunnel, and the packing ratio on the circuit performance are investigated in detail. Compared with a one-beam circuit, a larger output power of the two-beam circuit with the same beam power was observed by the simulation. Moreover, the start-oscillation current of two-beam circuit is much lower than the one-beam circuit with better performance. It will favor the miniaturized design of the high-power terahertz oscillator

  7. Enhancement of the output power of terahertz folded waveguide oscillator by two parallel electron beams

    Energy Technology Data Exchange (ETDEWEB)

    Li, Ke, E-mail: like.3714@163.com; Cao, Miaomiao, E-mail: mona486@yeah.net [Key Laboratory of High Power Microwave Sources and Technologies, Institute of Electronics, Chinese Academy of Sciences, Beijing 100190 (China); University of Chinese Academy of Sciences, Beijing 100190 (China); Liu, Wenxin, E-mail: lwenxin@mail.ie.ac.cn; Wang, Yong, E-mail: wangyong3845@sina.com [Key Laboratory of High Power Microwave Sources and Technologies, Institute of Electronics, Chinese Academy of Sciences, Beijing 100190 (China); Liao, Suying, E-mail: suying-liao@163.com [Air Force Airborne Academy, Guilin, Guangxi 541003 (China)

    2015-11-15

    A novel two-beam folded waveguide (FW) oscillator is presented for the purpose of gaining higher power with a small-size circuit compared with the normal FW oscillator. The high-frequency characteristics of the two-beam FW, including dispersion and interaction impedance, were investigated by the numerical simulation and compared with the one-beam FW. The radio-frequency loss of the two-beam FW was also analyzed. A 3-D particle-in-cell code CHIPIC was applied to analyze and optimize the performance of a G-band two-beam FW oscillator. The influences of the distance between the two beam tunnels, beam voltage, the number of periods, magnetic field, radius of beam tunnel, and the packing ratio on the circuit performance are investigated in detail. Compared with a one-beam circuit, a larger output power of the two-beam circuit with the same beam power was observed by the simulation. Moreover, the start-oscillation current of two-beam circuit is much lower than the one-beam circuit with better performance. It will favor the miniaturized design of the high-power terahertz oscillator.

  8. GUIDELINES FOR EVALUATION OF PSYCHOLOGICAL AND PEDAGOGICAL QUALITY CHARACTERISTICS OF ELECTRONIC EDUCATIONAL RESOURCES

    Directory of Open Access Journals (Sweden)

    Galina P. Lavrentieva

    2014-05-01

    Full Text Available The article highlights the causes of insufficient effective use of electronic learning resources and sets out the guidelines on ways to solve the aforementioned problems. The set of didactic, methodical, psychological, pedagogical, design and ergonomic quality requirements is considered for evaluation, selection and application of information and communication technologies in the educational process. The most appropriate mechanisms for the ICT introduction into the learning process are disclosed as it should meet the specific learning needs of the student and the objectives of the educational process. The guidance for psycho-educational assessment of quality of electronic educational resources is provided. It is argued that the effectiveness of the ICT use is to be improved by means of quality evaluation mechanisms involved into the educational process.

  9. Self-excited nonlinear plasma series resonance oscillations in geometrically symmetric capacitively coupled radio frequency discharges

    International Nuclear Information System (INIS)

    Donko, Z.; Schulze, J.; Czarnetzki, U.; Luggenhoelscher, D.

    2009-01-01

    At low pressures, nonlinear self-excited plasma series resonance (PSR) oscillations are known to drastically enhance electron heating in geometrically asymmetric capacitively coupled radio frequency discharges by nonlinear electron resonance heating (NERH). Here we demonstrate via particle-in-cell simulations that high-frequency PSR oscillations can also be excited in geometrically symmetric discharges if the driving voltage waveform makes the discharge electrically asymmetric. This can be achieved by a dual-frequency (f+2f) excitation, when PSR oscillations and NERH are turned on and off depending on the electrical discharge asymmetry, controlled by the phase difference of the driving frequencies

  10. Availability, Use and Constraints to Use of Electronic Information Resources by Postgraduates Students at the University of Ibadan

    Directory of Open Access Journals (Sweden)

    Dare Samuel Adeleke

    2017-12-01

    Full Text Available Availability, awareness and use of electronic resources provide access to authoritative, reliable, accurate and timely access to information. The use of electronic information resources (EIRs can enable innovation in teaching and increase timeliness in research of postgraduate students which will eventual result into encouragement of the expected research-led enquiry in this digital age. The study adopted a descriptive survey design. Samples of 300 of postgraduate students within seven out 13 Faculties were randomly selected. Data were collected using questionnaire designed to elicit response from respondents and data were analyzed using descriptive statistics methods percentages, mean, and standard deviation. Results indicated that internet was ranked most available and used in the university. Low level of usage of electronic resources, in particular, full texts data bases is linked to a number of constraints: Interrupted power supply was ranked highest among other factors as speed and capacity of computers, retrieval of records with high recall and low precision, retrieving records relevant to information need, lack of knowledge of search techniques to retrieve information effectively, non possession of requisite IT skills and problems accessing the internet. The study recommended that usage of electronic resources be made compulsory, intensifying awareness campaigns concerning the availability, training on use of electronic resources and the problem of power outage be addressed.

  11. Tunable Soft X-Ray Oscillators

    International Nuclear Information System (INIS)

    Wurtele, Jonathan; Gandhi, Punut; Gu, X.-W.; Fawley, William M.; Reinsch, Matthia; Penn, Gregory; Kim, K.-J.; Lindberg, Ryan; Zholents, Alexander

    2010-01-01

    A concept for a tunable soft x-ray free electron laser (FEL) photon source is presented and studied numerically. The concept is based on echo-enabled harmonic generation (EEHG), wherein two modulator-chicane sections impose high harmonic structure with much greater efficacy as compared to conventional high harmonic FELs that use only one modulator-chicane section. The idea proposed here is to replace the external laser power sources in the EEHG modulators with FEL oscillators, and to combine the bunching of the beam with the production of radiation. Tunability is accomplished by adjusting the magnetic chicanes while the two oscillators remain at a fixed frequency. This scheme eliminates the need to develop coherent sources with the requisite power, pulse length, and stability requirements by exploiting the MHz bunch repetition rates of FEL continuous wave (CW) sources driven by superconducting (SC) linacs. We present time-dependent GINGER simulation results for an EEHG scheme with an oscillator modulator at 43 nm employing 50percent reflective dielectric mirrors and a second modulator employing an external, 215-nm drive laser. Peak output of order 300 MW is obtained at 2.7 nm, corresponding to the 80th harmonic of 215 nm. An alternative single-cavity echo-oscillator scheme based on a 13.4 nm oscillator is investigated with time-independent simulations that a 180-MW peak power at final wavelength of 1.12 nm. Three alternate configurations that use separate bunches to produce the radiation for EEHG microbunching are also presented. Our results show that oscillator-based soft x-ray FELs driven by CWSC linacs are extremely attractive because of their potential to produce tunable radiation at high average power together with excellent longitudinal coherence and narrow spectral bandwidth.

  12. Tunable Soft X-Ray Oscillators

    Energy Technology Data Exchange (ETDEWEB)

    Wurtele, Jonathan; Gandhi, Punut; Gu, X-W; Fawley, William M; Reinsch, Matthia; Penn, Gregory; Kim, K-J; Lindberg, Ryan; Zholents, Alexander

    2010-09-17

    A concept for a tunable soft x-ray free electron laser (FEL) photon source is presented and studied numerically. The concept is based on echo-enabled harmonic generation (EEHG), wherein two modulator-chicane sections impose high harmonic structure with much greater efficacy as compared to conventional high harmonic FELs that use only one modulator-chicane section. The idea proposed here is to replace the external laser power sources in the EEHG modulators with FEL oscillators, and to combine the bunching of the beam with the production of radiation. Tunability is accomplished by adjusting the magnetic chicanes while the two oscillators remain at a fixed frequency. This scheme eliminates the need to develop coherent sources with the requisite power, pulse length, and stability requirements by exploiting the MHz bunch repetition rates of FEL continuous wave (CW) sources driven by superconducting (SC) linacs. We present time-dependent GINGER simulation results for an EEHG scheme with an oscillator modulator at 43 nm employing 50percent reflective dielectric mirrors and a second modulator employing an external, 215-nm drive laser. Peak output of order 300 MW is obtained at 2.7 nm, corresponding to the 80th harmonic of 215 nm. An alternative single-cavity echo-oscillator scheme based on a 13.4 nm oscillator is investigated with time-independent simulations that a 180-MW peak power at final wavelength of 1.12 nm. Three alternate configurations that use separate bunches to produce the radiation for EEHG microbunching are also presented. Our results show that oscillator-based soft x-ray FELs driven by CWSC linacs are extremely attractive because of their potential to produce tunable radiation at high average power together with excellent longitudinal coherence and narrow spectral bandwidth.

  13. Robust signatures of solar neutrino oscillation solutions

    CERN Document Server

    Bahcall, J N; Peña-Garay, C; Bahcall, John N.; Peña-Garay, Carlos

    2002-01-01

    With the goal of identifying signatures that select specific neutrino oscillation parameters, we test the robustness of global oscillation solutions that fit all the available solar and reactor experimental data. We use three global analysis strategies previously applied by different authors and also determine the sensitivity of the oscillation solutions to the critical nuclear fusion cross section, S_{17}(0), for the production of 8B. The neutral current to charged current ratio for SNO is predicted to be 3.5 +- 0.6 (1 sigma) for the favored LMA, LOW, and VAC solutions, which is separated from the no-oscillation value of 1.0 by much more than the expected experimental error. The predicted range of the day-night difference in charged current rates is between 0% and 21% (3 sigma) and is to be strongly correlated with the day-night effect for neutrino-electron scattering. A measurement by SNO of either a NC to CC ratio > 3.3 or a day-night difference > 10%, would favor a small region of the currently allowed LM...

  14. Large quantum dots with small oscillator strength

    DEFF Research Database (Denmark)

    Stobbe, Søren; Schlereth, T.W.; Höfling, S.

    2010-01-01

    We have measured the oscillator strength and quantum efficiency of excitons confined in large InGaAs quantum dots by recording the spontaneous emission decay rate while systematically varying the distance between the quantum dots and a semiconductor-air interface. The size of the quantum dots...... is measured by in-plane transmission electron microscopy and we find average in-plane diameters of 40 nm. We have calculated the oscillator strength of excitons of that size assuming a quantum-dot confinement given by a parabolic in-plane potential and a hard-wall vertical potential and predict a very large...... intermixing inside the quantum dots....

  15. Nonadiabatic three-neutrino oscillations in matter

    International Nuclear Information System (INIS)

    DOlivo, J.C.; Oteo, J.A.

    1996-01-01

    Oscillations of three neutrinos in matter are analyzed by using the Magnus expansion for the time-evolution operator. We derive a simple expression for the electron-neutrino survival probability which is applied to the examination of the effect of a third neutrino on the nonadiabatic flavor transformations. copyright 1996 The American Physical Society

  16. A Study on Developing Evaluation Criteria for Electronic Resources in Evaluation Indicators of Libraries

    Science.gov (United States)

    Noh, Younghee

    2010-01-01

    This study aimed to improve the current state of electronic resource evaluation in libraries. While the use of Web DB, e-book, e-journal, and other e-resources such as CD-ROM, DVD, and micro materials is increasing in libraries, their use is not comprehensively factored into the general evaluation of libraries and may diminish the reliability of…

  17. Topological and trivial magnetic oscillations in nodal loop semimetals

    Science.gov (United States)

    Oroszlány, László; Dóra, Balázs; Cserti, József; Cortijo, Alberto

    2018-05-01

    Nodal loop semimetals are close descendants of Weyl semimetals and possess a topologically dressed band structure. We argue by combining the conventional theory of magnetic oscillation with topological arguments that nodal loop semimetals host coexisting topological and trivial magnetic oscillations. These originate from mapping the topological properties of the extremal Fermi surface cross sections onto the physics of two dimensional semi-Dirac systems, stemming from merging two massless Dirac cones. By tuning the chemical potential and the direction of magnetic field, a sharp transition is identified from purely trivial oscillations, arising from the Landau levels of a normal two dimensional (2D) electron gas, to a phase where oscillations of topological and trivial origin coexist, originating from 2D massless Dirac and semi-Dirac points, respectively. These could in principle be directly identified in current experiments.

  18. Discrete oscillator design linear, nonlinear, transient, and noise domains

    CERN Document Server

    Rhea, Randall W

    2014-01-01

    Oscillators are an essential part of all spread spectrum, RF, and wireless systems, and today's engineers in the field need to have a firm grasp on how they are designed. Presenting an easy-to-understand, unified view of the subject, this authoritative resource covers the practical design of high-frequency oscillators with lumped, distributed, dielectric and piezoelectric resonators. Including numerous examples, the book details important linear, nonlinear harmonic balance, transient and noise analysis techniques. Moreover, the book shows you how to apply these techniques to a wide range of os

  19. Regulation of glycolytic oscillations by mitochondrial and plasma membrane H+-ATPases

    DEFF Research Database (Denmark)

    Olsen, Lars Folke; Andersen, Ann Zahle; Lunding, Anita

    2009-01-01

    ,3'-diethyloxacarbocyanine iodide. The responses of glycolytic and membrane potential oscillations to a number of inhibitors of glycolysis, mitochondrial electron flow, and mitochondrial and plasma membrane H(+)-ATPase were investigated. Furthermore, the glycolytic flux was determined as the rate of production of ethanol....../ATP antiporter and the mitochondrial F(0)F(1)-ATPase. The results further suggest that ATP hydrolysis, through the action of the mitochondrial F(0)F(1)-ATPase and plasma membrane H(+)-ATPase, are important in regulating these oscillations. We conclude that it is glycolysis that drives the oscillations...

  20. A combined muon-neutrino and electron-neutrino oscillation search at MiniBooNE

    Energy Technology Data Exchange (ETDEWEB)

    Monroe, Jocelyn Rebecca [Columbia Univ., New York, NY (United States)

    2006-01-01

    MiniBooNE seeks to corroborate or refute the unconfirmed oscillation result from the LSND experiment. If correct, the result implies that a new kind of massive neutrino, with no weak interactions, participates in neutrino oscillations. MiniBooNE searches for vμ → ve oscillations with the Fermi National Accelerator Laboratory 8 GeV beam line, which produces a vμ beam with an average energy of ~ 0.8 GeV and an intrinsic ve content of 0.4%. The neutrino detector is a 6.1 m radius sphere filled with CH2, viewed by 1540 photo-multiplier tubes, and located 541 m downstream from the source. This work focuses on the estimation of systematic errors associated with the neutrino flux and neutrino interaction cross section predictions, and in particular, on constraining these uncertainties using in-situ MiniBooNE vμ charged current quasielastic (CCQE) scattering data. A data set with ~ 100,000 events is identified, with 91% CCQE purity. This data set is used to measure several parameters of the CCQE cross section: the axial mass, the Fermi momentum, the binding energy, and the functional dependence of the axial form factor on four-momentum transfer squared. Constraints on the vμ and ve fluxes are derived using the vμ CCQE data set. A Monte Carlo study of a combined vμ disappearance and ve appearance oscillation fit is presented, which improves the vμ → ve oscillation sensitivity of MiniBooNE with respect to a ve appearance-only fit by 1.2-1.5σ, depending on the value of Δm2.

  1. An experimental study of the regulation of glycolytic oscillations in yeast

    DEFF Research Database (Denmark)

    Schrøder, Tine Daa; Özalp, Veli Cengiz; Lunding, Anita

    2013-01-01

    We have studied oscillating glycolysis in the strain BY4743 and isogenic strains with deletions of genes encoding enzymes in glycolysis, mitochondrial electron transport and ATP synthesis. We found that deletion of the gene encoding the hexokinase 1 isoform does not affect the oscillations while...... to processes within glycolysis also processes outside this pathway contribute to the control of the oscillatory behaviour....

  2. Neutrino mixing, oscillations and decoherence in astrophysics and cosmology

    Science.gov (United States)

    Ho, Chiu Man

    2007-08-01

    This thesis focuses on a finite-temperature field-theoretical treatment of neutrino oscillations in hot and dense media. By implementing the methods of real-time non-equilibrium field theory, we study the dynamics of neutrino mixing, oscillations, decoherence and relaxation in astrophysical and cosmological environments. We first study neutrino oscillations in the early universe in the temperature regime prior to the epoch of Big Bang Nucleosynthesis (BBN). The dispersion relations and mixing angles in the medium are found to be helicity-dependent, and a resonance like the Mikheyev-Smirnov- Wolfenstein (MSW) effect is realized. The oscillation time scales are found to be longer near a resonance and shorter for off-resonance high-energy neutrinos. We then investigate the space-time propagation of neutrino wave-packets just before BBN. A phenomenon of " frozen coherence " is found to occur if the longitudinal dispersion catches up with the progressive separation between the mass eigenstates, before the coherence time limit has been reached. However, the transverse dispersion occurs at a much shorter scale than all other possible time scales in the medium, resulting in a large suppression in the transition probabilities from electron-neutrino to muon-neutrino. We also explore the possibility of charged lepton mixing as a consequence of neutrino mixing in the early Universe. We find that charged leptons, like electrons and muons, can mix and oscillate resonantly if there is a large lepton asymmetry in the neutrino sector. We study sterile neutrino production in the early Universe via active-sterile oscillations. We provide a quantum field theoretical reassessment of the quantum Zeno suppression on the active-to-sterile transition probability and its time average. We determine the complete conditions for quantum Zeno suppression. Finally, we examine the interplay between neutrino mixing, oscillations and equilibration in a thermal medium, and the corresponding non

  3. Characterization of the Vectron PX-570 Crystal Oscillator for Use in Harsh Environments

    Science.gov (United States)

    Li, Jacob; Patterson, Richard L.; Hammoud, Ahmad

    2012-01-01

    Computing hardware, data-acquisition systems, communications systems, and many electronic control systems require well-controlled timing signals for proper and accurate operation. These signals are, in most cases, provided by circuits that employ crystal oscillators due to availability, cost, ease of operation, and accuracy. In some cases, the electronic systems are expected to survive and operate under harsh conditions that include exposure to extreme temperatures. These applications exist in terrestrial systems as well as in aerospace products. Well-logging, geothermal systems, and industrial process control are examples of ground-based applications, while distributed jet engine control in aircraft, space-based observatories (such as the James Webb Space Telescope), satellites, and lunar and planetary landers are typical environments where electronics are exposed to harsh operating conditions. To ensure these devices produce reliable results, the digital heartbeat from the oscillator must deliver a stable signal that is not affected by external temperature or other conditions. One such solution is a recently introduced commercial-off-the-shelf (COTS) oscillator, the PX-570 series from Vectron International. The oscillator was designed for high-temperature applications and as proof, the crystal oscillator was subjected to a wide suite of tests to determine its ruggedness for operation in harsh environments. The tests performed by Vectron included electrical characterization under wide range of temperature, accelerated life test/aging, shock and vibration, internal moisture analysis, ESD threshold, and latch-up testing. The parametric evaluation was performed on the oscillator's frequency, output signal rise and fall times, duty cycle, and supply current over the temperature range of -125 C to +230 C. The evaluations also determined the effects of thermal cycling and the oscillator's re-start capability at extreme hot and cold temperatures. These thermal cycling

  4. THE MODEL OF LINGUISTIC TEACHERS’ COMPETENCY DEVELOPMENT ON DESIGNING MULTIMEDIA ELECTRONIC EDUCATIONAL RESOURCES IN THE MOODLE SYSTEM

    OpenAIRE

    Anton M. Avramchuk

    2017-01-01

    The article is devoted to the problem of developing the competency of teachers of language disciplines on designing multimedia electronic educational resources in the Moodle system. The concept of "the competence of teachers of language disciplines on designing multimedia electronic educational resources in the Moodle system" is justified and defined. Identified and characterized the components by which the levels of the competency development of teachers of language disciplines on designing ...

  5. Study of the appearance of oscillating electron neutrinos issued from muon neutrino beam in the K2K experiment; Etude de l'apparition de neutrinos electroniques oscillant a partir de neutrinos muoniques du faisceau de l'experience K2K

    Energy Technology Data Exchange (ETDEWEB)

    Argyriades, J

    2006-05-15

    The work presented in this thesis has been done in the K2K experiment. His principle consists in the use of a beam of muon neutrinos, which flux has been measured at short and long distances. Those data enable us to study the effects of neutrino oscillation, particularly by measuring {nu}{sub {mu}} disappearance. Although this is not an appearance experiment, electronic neutrinos oscillation has been searched. In spite of no signal of appearance, this study enables to constrain oscillation parameters ({delta}m{sub 23}{sup 2}, sin{sup 2}2{theta}{sub 13}). With one event for 1,07 expected event from background, the exclusion area edges are close to the best actual limits, provided by Chooz experiment. By setting {delta}m{sub 23}{sup 2}.= 2,8.10{sup -3} eV{sup 2}, a limit at 90% confident level is reached: sin{sup 2}2{theta}{sub 13} < 0,2. (author)

  6. Determining the level of awareness of the physicians in using the variety of electronic information resources and the effecting factors.

    Science.gov (United States)

    Papi, Ahmad; Ghazavi, Roghayeh; Moradi, Salimeh

    2015-01-01

    Understanding of the medical society's from the types of information resources for quick and easy access to information is an imperative task in medical researches and management of the treatment. The present study was aimed to determine the level of awareness of the physicians in using various electronic information resources and the factors affecting it. This study was a descriptive survey. The data collection tool was a researcher-made questionnaire. The study population included all the physicians and specialty physicians of the teaching hospitals affiliated to Isfahan University of Medical Sciences and numbered 350. The sample size based on Morgan's formula was set at 180. The content validity of the tool was confirmed by the library and information professionals and the reliability was 95%. Descriptive statistics were used including the SPSS software version 19. On reviewing the need of the physicians to obtain the information on several occasions, the need for information in conducting the researches was reported by the maximum number of physicians (91.9%) and the usage of information resources, especially the electronic resources, formed 65.4% as the highest rate with regard to meeting the information needs of the physicians. Among the electronic information databases, the maximum awareness was related to Medline with 86.5%. Among the various electronic information resources, the highest awareness (43.3%) was related to the E-journals. The highest usage (36%) was also from the same source. The studied physicians considered the most effective deterrent in the use of electronic information resources as being too busy and lack of time. Despite the importance of electronic information resources for the physician's community, there was no comprehensive knowledge of these resources. This can lead to less usage of these resources. Therefore, careful planning is necessary in the hospital libraries in order to introduce the facilities and full capabilities of the

  7. Electron eigen-oscillations and ballistic modes of a stable plasma

    International Nuclear Information System (INIS)

    Jungwirth, K.

    1976-01-01

    The relation between plasma responses to singular and regular initial perturbations is established. Time scaling is introduced to separate time intervals for which eigen-oscillations (Landau solution) are dominant from such where ballistic modes prevail. The enhanced role is demonstrated of the ballistic modes for an initially perturbed field-free plasma including the phenomenon of plasma wave echoes. (author)

  8. Search on neutrino oscillation νμ→νe in the NOMAD experiment

    International Nuclear Information System (INIS)

    Valuev, Viatcheslav

    1998-01-01

    The NOMAD experiment is a search for neutrino oscillations using the large band neutrino beams of SPS at CERN. It is dealing with the two oscillation modes: ν μ →ν τ and ν μ →ν e . This thesis presents the results obtained in the search of oscillations ν μ →ν e with the data produced by NOMAD in 1995 and 1996. The first two chapters deal with the short presentation of the neutrino oscillation phenomenology and a summary of the experimental situation. The third chapter describes the experimental setup of the NOMAD detector at CERN, designed to identify the interactions of ν e by means of the charged current. This is done with the transition radiation detector (TRD) designed to separate the electrons from pions with a rejection factor higher then 1000 at an electron efficiency of 90%, in the 1 - 50 GeV region. Details about the TRD operation are given in chapter four. The fifth chapter gives the algorithms of electron-pion separation as well as their performances. The last two chapters present the analysis of the ν μ →ν e data obtained in 1995 and 1996 and the final results. The conclusion is that the available data give no evidence for the neutrino oscillations. The upper limit obtained for the mixing angle is sin 2 (2θ) -3 (90% C.L.). This result eliminates completely the oscillation region of LSND experiment (Liquid Scintillator Neutrino Detector) at LAMPF for Δm 2 > 15 eV 2 and gives the most constraining world limit on sin 2 (2θ) for Δm 2 > 20 eV 2

  9. Managing Selection for Electronic Resources: Kent State University Develops a New System to Automate Selection

    Science.gov (United States)

    Downey, Kay

    2012-01-01

    Kent State University has developed a centralized system that manages the communication and work related to the review and selection of commercially available electronic resources. It is an automated system that tracks the review process, provides selectors with price and trial information, and compiles reviewers' feedback about the resource. It…

  10. Lagrangian approach in spin-oscillations problem

    Directory of Open Access Journals (Sweden)

    P.V. Pyshkin

    2014-12-01

    Full Text Available Lagrangian of electronic liquid in magneto-inhomogeneous micro-conductor has been constructed. A corresponding Euler-Lagrange equation has been solved. It was shown that the described system has eigenmodes of spin polarization and total electric current oscillations. The suggested approach permits to study the spin dynamics in an open-circuit which contains capacitance and/or inductivity.

  11. Experiment on a large-diameter plasma-filled backward-wave oscillator

    International Nuclear Information System (INIS)

    Ogura, K.; Minami, K.; Kurashina, K.I.; Kim, W.; Watanabe, T.; Ishii, K.; Sugito, S.

    1995-01-01

    A large-diameter plasma-filled backward-wave oscillator (BWO) is investigated experimentally. The parameters of slow wave structure are chosen so that the oscillation frequency is about 20GHz at 60keV beam energy. Plasma is produced by the beam and has favorable effects for beam propagation and Cerenkov oscillations. The output power of the BWO with plasma is observed to be three to six times that of vacuum BWO. The power level is several kilowatts and the efficiency is about 0.01%. For Cerenkov oscillations of a large-diameter BWO, the beam energy mainly determines the starting conditions for oscillation. The output power is strongly enhanced when the guiding magnetic field approaches the fundamental electron cyclotron resonance. This mechanism is closely related to the anomalous Doppler cyclotron resonance. The maximum power of 480kW with an efficiency of 5% is achieved even for a relatively low beam energy of 60keV. ((orig.))

  12. Tuning the electronic structure of bulk FeSe with chemical pressure using quantum oscillations and angle resolved photoemission spectroscopy (ARPES)

    Science.gov (United States)

    Coldea, Amalia

    FeSe is a unique and intriguing superconductor which can be tuned into a high temperature superconducting state using applied pressure, chemical intercalation and surface doping. In the absence of magnetism, the structural transition in FeSe is believed to be electronically driven, with the orbital degrees of freedom playing an important part. This scenario supports the stabilization of a nematic state in FeSe, which manifests as a Fermi surface deformation in the presence of strong interactions, as detected by ARPES. Another manifestation of the nematicity is the enhanced nematic susceptibility determined from elastoresistance measurements under applied strain. Isovalent Sulphur substitution onto the Selenium site constitutes a chemical pressure, which subtly modifies the electronic structure of FeSe, suppressing the structural transition without inducing high temperature superconductivity. I will present the evolution of the electronic structure with chemical pressure in FeSe, as determined from quantum oscillations and ARPES studies and I will discuss the suppression of the nematic electronic state and the role of electronic correlations. Experiments were performed at high magnetic field facilities in Tallahassee, Nijmegen and Toulouse and Diamond Light Source, UK. This work is mainly supported by EPSRC, UK (EP/I004475/1, EP/I017836/1) and I acknowledge my collaborators from Refs. .

  13. Phase locking in backward-wave oscillators with strong end reflections

    International Nuclear Information System (INIS)

    Nusinovich, G. S.; Sinitsyn, O. V.; Rodgers, J.; Shkvarunets, A. G.; Carmel, Y.

    2007-01-01

    The theory of phase-locked oscillations in a backward-wave oscillator with strong end reflections is developed. Numerical results demonstrate that the locking bandwidth of such a device phase-locked by a prebunched electron beam can be twice the bandwidth of a resonator formed by a waveguide with strong end reflections. It is also shown that the device can operate with the efficiency exceeding 50% and that, in some cases, it can exhibit a hysteresis in the process of tuning the signal frequency. The applicability of the results obtained to the experiments with the plasma-assisted backward-wave oscillator currently underway at the University of Maryland is discussed

  14. End-of-life resource recovery from emerging electronic products

    DEFF Research Database (Denmark)

    Parajuly, Keshav; Habib, Komal; Cimpan, Ciprian

    2016-01-01

    Integrating product design with appropriate end-of-life (EoL) processing is widely recognized to have huge potentials in improving resource recovery from electronic products. In this study, we investigate both the product characteristics and EoL processing of robotic vacuum cleaner (RVC), as a case...... of emerging electronic product, in order to understand the recovery fate of different materials and its linkage to product design. Ten different brands of RVC were dismantled and their material composition and design profiles were studied. Another 125 RVCs (349 kg) were used for an experimental trial...... at a conventional ‘shred-and-separate’ type preprocessing plant in Denmark. A detailed material flow analysis was performed throughout the recycling chain. The results show a mismatch between product design and EoL processing, and the lack of practical implementation of ‘Design for EoL’ thinking. In the best...

  15. Oscillating two-stream instability of laser wakefield-driven plasma ...

    Indian Academy of Sciences (India)

    on electrons, driving the low-frequency mode, i.e., causing local density depression n (ω, k). This density perturbation in conjunction with the oscillating electron velocity v0 at (ω0, k0) produces nonlinear density perturbations nNL. 1,2 at (ω1,2, k1,2) that drive the sidebands. In §2, the local theory of OTSI of laser ...

  16. Use of electronic sales data to tailor nutrition education resources for an ethnically diverse population.

    Science.gov (United States)

    Eyles, H; Rodgers, A; Ni Mhurchu, C

    2010-02-01

    Nutrition education may be most effective when personally tailored. Individualised electronic supermarket sales data offer opportunities to tailor nutrition education using shopper's usual food purchases. The present study aimed to use individualised electronic supermarket sales data to tailor nutrition resources for an ethnically diverse population in a large supermarket intervention trial in New Zealand. Culturally appropriate nutrition education resources (i.e. messages and shopping lists) were developed with the target population (through two sets of focus groups) and ethnic researchers. A nutrient database of supermarket products was developed using retrospective sales data and linked to participant sales to allow tailoring by usual food purchases. Modified Heart Foundation Tick criteria were used to identify 'healthier' products in the database suitable for promotion in the resources. Rules were developed to create a monthly report listing the tailored and culturally targeted messages to be sent to each participant, and to produce automated, tailored shopping lists. Culturally targeted nutrition messages (n = 864) and shopping lists (n = 3 formats) were developed. The food and nutrient database (n = 3000 top-selling products) was created using 12 months of retrospective sales data, and comprised 60%'healthier' products. Three months of baseline sales data were used to determine usual food purchases. Tailored resources were successfully mailed to 123 Māori, 52 Pacific and 346 non-Māori non-Pacific participants over the 6-month trial intervention period. Electronic supermarket sales data can be used to tailor nutrition education resources for a large number of ethnically diverse supermarket shoppers.

  17. Quenching oscillating behaviors in fractional coupled Stuart-Landau oscillators

    Science.gov (United States)

    Sun, Zhongkui; Xiao, Rui; Yang, Xiaoli; Xu, Wei

    2018-03-01

    Oscillation quenching has been widely studied during the past several decades in fields ranging from natural sciences to engineering, but investigations have so far been restricted to oscillators with an integer-order derivative. Here, we report the first study of amplitude death (AD) in fractional coupled Stuart-Landau oscillators with partial and/or complete conjugate couplings to explore oscillation quenching patterns and dynamics. It has been found that the fractional-order derivative impacts the AD state crucially. The area of the AD state increases along with the decrease of the fractional-order derivative. Furthermore, by introducing and adjusting a limiting feedback factor in coupling links, the AD state can be well tamed in fractional coupled oscillators. Hence, it provides one an effective approach to analyze and control the oscillating behaviors in fractional coupled oscillators.

  18. Oscillations and Stability of Plasma in an External High-Frequency Electric Field

    International Nuclear Information System (INIS)

    Aliev, Ju.M.; Gorbunov, L.M.; Silin, V.P.; Uotson, H.

    1966-01-01

    A theory is developed for the oscillations and stability of plasma in a strong external HF electric field. The kinetic equation with self-congruent reciprocity is linearized for weak deviations from the ground state. Since the latter depends on an external HF field, the linearized equation obtained has coefficients with a periodic time dependence. From this equation and also from Maxwell's equations there is derived a dispersion equation for plasma oscillations that represents the zero value of the infinite order determinant, and that is solved both for external field frequencies considerably exceeding the electron Langmuir frequency and for frequencies that are less. The external HF field changes the oscillation branches in a plasma without an external field, and also leads to a new low-frequency oscillation branch. Movement of particles in the HF field gives spatial dispersion. If the frequency of the field exceeds the election Langmuir frequency, the plasma oscillations are stable. At frequencies less than this level there occurs a build-up of low-frequency oscillations. Here the maximum of the build-up occurs when the external field frequencies approach the electron Langmuir frequency and is equal to the product of the Langmuir frequency and the one-third power of the electron-ion mass ratio. Away from the resonance, -the increment of build-up has the same order of magnitude as the ion Langmuir frequency. An external magnetic field increases the number of possible natural plasma oscillations and thereby increases the possibility of resonance with the external HF field. Allowance for the thermal motion of the particles enables one to determine the attenuation of the oscillations in question. Expressions for the decrements are derived. The effect of the external HF field on a plasma in which there are beams is also discussed. An HF field has a destabilizing effect on a system of this kind, since on the one hand there can be a build-up of fresh, low

  19. Pure odd-order oscillators with constant excitation

    Science.gov (United States)

    Cveticanin, L.

    2011-02-01

    In this paper the excited vibrations of a truly nonlinear oscillator are analyzed. The excitation is assumed to be constant and the nonlinearity is pure (without a linear term). The mathematical model is a second-order nonhomogeneous differential equation with strong nonlinear term. Using the first integral, the exact value of period of vibration i.e., angular frequency of oscillator described with a pure nonlinear differential equation with constant excitation is analytically obtained. The closed form solution has the form of gamma function. The period of vibration depends on the value of excitation and of the order and coefficient of the nonlinear term. For the case of pure odd-order-oscillators the approximate solution of differential equation is obtained in the form of trigonometric function. The solution is based on the exact value of period of vibration. For the case when additional small perturbation of the pure oscillator acts, the so called 'Cveticanin's averaging method' for a truly nonlinear oscillator is applied. Two special cases are considered: one, when the additional term is a function of distance, and the second, when damping acts. To prove the correctness of the method the obtained results are compared with those for the linear oscillator. Example of pure cubic oscillator with constant excitation and linear damping is widely discussed. Comparing the analytically obtained results with exact numerical ones it is concluded that they are in a good agreement. The investigations reported in the paper are of special interest for those who are dealing with the problem of vibration reduction in the oscillator with constant excitation and pure nonlinear restoring force the examples of which can be found in various scientific and engineering systems. For example, such mechanical systems are seats in vehicles, supports for machines, cutting machines with periodical motion of the cutting tools, presses, etc. The examples can be find in electronics

  20. Availability, Level of Use and Constraints to Use of Electronic Resources by Law Lecturers in Public Universities in Nigeria

    Science.gov (United States)

    Amusa, Oyintola Isiaka; Atinmo, Morayo

    2016-01-01

    (Purpose) This study surveyed the level of availability, use and constraints to use of electronic resources among law lecturers in Nigeria. (Methodology) Five hundred and fifty-two law lecturers were surveyed and four hundred and forty-two responded. (Results) Data analysis revealed that the level of availability of electronic resources for the…

  1. Oscillation control system for electric motor drive

    Science.gov (United States)

    Slicker, J.M.; Sereshteh, A.

    1988-08-30

    A feedback system for controlling mechanical oscillations in the torsionally complaint drive train of an electric or other vehicle. Motor speed is converted in a processor to estimate state signals in which a plant model which are used to electronically modify the torque commands applied to the motor. 5 figs.

  2. Effect of structural disorder on quantum oscillations in graphite

    Energy Technology Data Exchange (ETDEWEB)

    Camargo, B. C., E-mail: b.c-camargo@yahoo.com.br; Kopelevich, Y. [Instituto de Fisica Gleb Wataghin, Universidade Estadual de Campinas, Unicamp 13083-970, Campinas, São Paulo (Brazil); Usher, A.; Hubbard, S. B. [School of Physics, University of Exeter, Stocker Road, Exeter EX4 4QL (United Kingdom)

    2016-01-18

    We have studied the effect of structural disorder on the de Haas van Alphen and Shubnikov de Haas quantum oscillations measured in natural, Kish, and highly oriented pyrolytic graphite samples at temperatures down to 30 mK and at magnetic fields up to 14 T. The measurements were performed on different samples characterized by means of x-ray diffractometry, transmission electron microscopy, and atomic-force microscopy techniques. Our results reveal a correlation between the amplitude of quantum oscillations and the sample surface roughness.

  3. Rabi oscillations in the dissociative continuum: Rotation and alignment effects

    Science.gov (United States)

    Granucci, Giovanni; Magnier, Sylvie; Persico, Maurizio

    2002-01-01

    We have simulated a set of experiments in which Rabi oscillations are induced in bound-free and free-free transitions of a diatomic molecule. Dissociative vibrational states belonging to different electronic terms are involved. We show analytically and confirm computationally that a simple relationship exists between the one-dimensional dynamics of a molecule with fixed orientation with respect to the polarization of the radiation field and the three-dimensional dynamics of a rotating system. It is demonstrated that sufficiently short laser pulses can induce oscillations in the probabilities of two coupled electronic states, and in the yields of the respective dissociation products, as functions of the radiation intensity. As a result of molecular rotation the oscillations are damped but not washed out. The initial thermal distribution on several rotational levels has a negligible effect on the photodissociation yields and other experimentally relevant quantities. Since the molecule undergoes a strong alignment along the polarization axis of the laser field, the ejection of atoms and ions is anisotropic. We have chosen the well known diatomic ion Na2+ as a convenient example.

  4. Metal-nonmetal oscillations in doped blue phosphorene: a first-principles study

    Science.gov (United States)

    Li, Hui; Zhang, Liwei; Cai, Xiaolin; Li, Xiaohua; Wang, Baoji; Yu, Weiyang; Zhao, Ruiqi

    2018-05-01

    Based on density functional theory (DFT), we have systematically investigated the geometry structure and electronic properties of group IIIA, IVA, VA, and VIA atoms doped blue phosphorene, such as B‑, C‑, N‑, O‑, Al‑, Si- and S-doped blue phosphorene systems. We find that the electronic properties of blue phosphorene are drastically modified by the number of valence electrons in dopant atoms. An intriguing general rule of metal-nonmetal oscillations have been obtained that the dopant atoms from even group, such as IVA and VIA, lead to metal properties, while dopant atoms from odd group, such as IIIA and VA, give rise to semiconductor properties, which is different from traditional n or p doping effect in bulk case. This even–odd oscillating behavior is attributed to the peculiar bonding characteristics of blue phosphorene and the strong hybridization of sp orbitals between dopants and blue phosphorene. Then the underlying mechanism has been investigated with the electronic filling analysis. These results pave an intriguing way to tune the transport properties of electronic and photoelectronic devices based on blue phosphorene.

  5. Quantum oscillations in nodal line systems

    Science.gov (United States)

    Yang, Hui; Moessner, Roderich; Lim, Lih-King

    2018-04-01

    We study signatures of magnetic quantum oscillations in three-dimensional nodal line semimetals at zero temperature. The extended nature of the degenerate bands can result in a Fermi surface geometry with topological genus one, as well as a Fermi surface of electron and hole pockets encapsulating the nodal line. Moreover, the underlying two-band model to describe a nodal line is not unique, in that there are two classes of Hamiltonian with distinct band topology giving rise to the same Fermi-surface geometry. After identifying the extremal cyclotron orbits in various magnetic field directions, we study their concomitant Landau levels and resulting quantum oscillation signatures. By Landau-fan-diagram analyses, we extract the nontrivial π Berry phase signature for extremal orbits linking the nodal line.

  6. Extremely large magnetoresistance and electronic structure of TmSb

    Science.gov (United States)

    Wang, Yi-Yan; Zhang, Hongyun; Lu, Xiao-Qin; Sun, Lin-Lin; Xu, Sheng; Lu, Zhong-Yi; Liu, Kai; Zhou, Shuyun; Xia, Tian-Long

    2018-02-01

    We report the magnetotransport properties and the electronic structure of TmSb. TmSb exhibits extremely large transverse magnetoresistance and Shubnikov-de Haas (SdH) oscillation at low temperature and high magnetic field. Interestingly, the split of Fermi surfaces induced by the nonsymmetric spin-orbit interaction has been observed from SdH oscillation. The analysis of the angle-dependent SdH oscillation illustrates the contribution of each Fermi surface to the conductivity. The electronic structure revealed by angle-resolved photoemission spectroscopy (ARPES) and first-principles calculations demonstrates a gap at the X point and the absence of band inversion. Combined with the trivial Berry phase extracted from SdH oscillation and the nearly equal concentrations of electron and hole from Hall measurements, it is suggested that TmSb is a topologically trivial semimetal and the observed XMR originates from the electron-hole compensation and high mobility.

  7. A systematic review of portable electronic technology for health education in resource-limited settings.

    Science.gov (United States)

    McHenry, Megan S; Fischer, Lydia J; Chun, Yeona; Vreeman, Rachel C

    2017-08-01

    The objective of this study is to conduct a systematic review of the literature of how portable electronic technologies with offline functionality are perceived and used to provide health education in resource-limited settings. Three reviewers evaluated articles and performed a bibliography search to identify studies describing health education delivered by portable electronic device with offline functionality in low- or middle-income countries. Data extracted included: study population; study design and type of analysis; type of technology used; method of use; setting of technology use; impact on caregivers, patients, or overall health outcomes; and reported limitations. Searches yielded 5514 unique titles. Out of 75 critically reviewed full-text articles, 10 met inclusion criteria. Study locations included Botswana, Peru, Kenya, Thailand, Nigeria, India, Ghana, and Tanzania. Topics addressed included: development of healthcare worker training modules, clinical decision support tools, patient education tools, perceptions and usability of portable electronic technology, and comparisons of technologies and/or mobile applications. Studies primarily looked at the assessment of developed educational modules on trainee health knowledge, perceptions and usability of technology, and comparisons of technologies. Overall, studies reported positive results for portable electronic device-based health education, frequently reporting increased provider/patient knowledge, improved patient outcomes in both quality of care and management, increased provider comfort level with technology, and an environment characterized by increased levels of technology-based, informal learning situations. Negative assessments included high investment costs, lack of technical support, and fear of device theft. While the research is limited, portable electronic educational resources present promising avenues to increase access to effective health education in resource-limited settings, contingent

  8. Biological conditions for oscillations and chaos generated by multispecies competition

    NARCIS (Netherlands)

    Huisman, J; Weissing, FJ

    2001-01-01

    We investigate biological mechanisms that generate oscillations and chaos in multispecies competition models. For this purpose, we use a competition model concerned with competition for abiotic essential resources. Because phytoplankton and plants consume quite a number of abiotic essential

  9. Oscillators and Eigenvalues

    DEFF Research Database (Denmark)

    Lindberg, Erik

    1997-01-01

    In order to obtain insight in the nature of nonlinear oscillators the eigenvalues of the linearized Jacobian of the differential equations describing the oscillator are found and displayed as functions of time. A number of oscillators are studied including Dewey's oscillator (piecewise linear wit...... with negative resistance), Kennedy's Colpitts-oscillator (with and without chaos) and a new 4'th order oscillator with hyper-chaos....

  10. SAGES: a suite of freely-available software tools for electronic disease surveillance in resource-limited settings.

    Directory of Open Access Journals (Sweden)

    Sheri L Lewis

    Full Text Available Public health surveillance is undergoing a revolution driven by advances in the field of information technology. Many countries have experienced vast improvements in the collection, ingestion, analysis, visualization, and dissemination of public health data. Resource-limited countries have lagged behind due to challenges in information technology infrastructure, public health resources, and the costs of proprietary software. The Suite for Automated Global Electronic bioSurveillance (SAGES is a collection of modular, flexible, freely-available software tools for electronic disease surveillance in resource-limited settings. One or more SAGES tools may be used in concert with existing surveillance applications or the SAGES tools may be used en masse for an end-to-end biosurveillance capability. This flexibility allows for the development of an inexpensive, customized, and sustainable disease surveillance system. The ability to rapidly assess anomalous disease activity may lead to more efficient use of limited resources and better compliance with World Health Organization International Health Regulations.

  11. Use and Cost of Electronic Resources in Central Library of Ferdowsi University Based on E-metrics

    Directory of Open Access Journals (Sweden)

    Mohammad Reza Davarpanah

    2012-07-01

    Full Text Available The purpose of this study was to investigate the usage of electronic journals in Ferdowsi University, Iran based on e-metrics. The paper also aimed to emphasize the analysis of cost-benefit and the correlation between the journal impact factors and the usage data. In this study experiences of Ferdowsi University library on licensing and usage of electronic resources was evaluated by providing a cost-benefit analysis based on the cost and usage statistics of electronic resources. Vendor-provided data were also compared with local usage data. The usage data were collected by tracking web-based access locally, and by collecting vender-provided usage data. The data sources were one-year of vendor-supplied e-resource usage data such as Ebsco, Elsevier, Proquest, Emerald, Oxford and Springer and local usage data collected from the Ferdowsi university web server. The study found that actual usage values differ for vendor-provided data and local usage data. Elsevier has got the highest usage degree in searches, sessions and downloads. Statistics also showed that a small number of journals satisfy significant amount of use while the majority of journals were used less frequent and some were never used at all. The users preferred the PDF rather than HTML format. The data in subject profile suggested that the provided e-resources were best suited to certain subjects. There was no correlation between IF and electronic journal use. Monitoring the usage of e-resources gained increasing importance for acquisition policy and budget decisions. The article provided information about local metrics for the six surveyed vendors/publishers, e.g. usage trends, requests per package, cost per use as related to the scientific specialty of the university.

  12. Destabilization of the electron Bernstein modes by runaway electrons

    International Nuclear Information System (INIS)

    Hitchcock, D.A.; Mahajan, S.M.

    1982-01-01

    It is shown that the electromagnetic finite k/sub parallel/ electron Bernstein mode can be destabilized by the runaway electron distribution which results from the quasilinear action of the magnetized plasma oscillation. This mechanism is shown to yield growth rates of the order of 10 8 sec -1 and is suggested as a mechanism for the enchanced cyclotron harmonic emission in the presence of runaway electrons

  13. Search on neutrino oscillation {nu}{sub {mu}}{yields}{nu}{sub e} in the NOMAD experiment; Recherches des oscillations de neutrinos {nu}{sub {mu}}{yields}{nu}{sub e} dans l`experience NOMAD

    Energy Technology Data Exchange (ETDEWEB)

    Valuev, Viatcheslav [Paris-7 Univ., 75 (France)

    1998-07-07

    The NOMAD experiment is a search for neutrino oscillations using the large band neutrino beams of SPS at CERN. It is dealing with the two oscillation modes: {nu}{sub {mu}}{yields}{nu}{sub {tau}} and {nu}{sub {mu}}{yields}{nu}{sub e}. This thesis presents the results obtained in the search of oscillations {nu}{sub {mu}}{yields}{nu}{sub e} with the data produced by NOMAD in 1995 and 1996. The first two chapters deal with the short presentation of the neutrino oscillation phenomenology and a summary of the experimental situation. The third chapter describes the experimental setup of the NOMAD detector at CERN, designed to identify the interactions of {nu}{sub e} by means of the charged current. This is done with the transition radiation detector (TRD) designed to separate the electrons from pions with a rejection factor higher then 1000 at an electron efficiency of 90%, in the 1 - 50 GeV region. Details about the TRD operation are given in chapter four. The fifth chapter gives the algorithms of electron-pion separation as well as their performances. The last two chapters present the analysis of the {nu}{sub {mu}}{yields}{nu}{sub e} data obtained in 1995 and 1996 and the final results. The conclusion is that the available data give no evidence for the neutrino oscillations. The upper limit obtained for the mixing angle is sin{sup 2}(2{theta}) < 1.3 {center_dot} 10{sup -3} (90% C.L.). This result eliminates completely the oscillation region of LSND experiment (Liquid Scintillator Neutrino Detector) at LAMPF for {Delta}m{sup 2} > 15 eV{sup 2} and gives the most constraining world limit on sin{sup 2}(2{theta}) for {Delta}m{sup 2} > 20 eV{sup 2} 123 refs., 82 figs., 37 tabs.

  14. Spherical ion oscillations in a positive polarity gridded inertial-electrostatic confinement device

    Energy Technology Data Exchange (ETDEWEB)

    Bandara, R.; Khachan, J. [Plasma Physics, School of Physics, University of Sydney, Camperdown, New South Wales 2006 (Australia)

    2013-07-15

    A pulsed, positive polarity gridded inertial electrostatic confinement device has been investigated experimentally, using a differential emissive probe and potential traces as primary diagnostics. Large amplitude oscillations in the plasma current and plasma potential were observed within a microsecond of the discharge onset, which are indicative of coherent ion oscillations about a temporarily confined excess of recirculating electron space charge. The magnitude of the depth of the potential well in the established virtual cathode was determined using a differential emissive Langmuir probe, which correlated well to the potential well inferred from the ion oscillation frequency for both hydrogen and argon experiments. It was found that the timescale for ion oscillation dispersion is strongly dependent on the neutral gas density, and weakly dependent on the peak anode voltage. The cessation of the oscillations was found to be due to charge exchange processes converting ions to high velocity neutrals, causing the abrupt de-coherence of the oscillations through an avalanche dispersion in phase space.

  15. Spherical ion oscillations in a positive polarity gridded inertial-electrostatic confinement device

    Science.gov (United States)

    Bandara, R.; Khachan, J.

    2013-07-01

    A pulsed, positive polarity gridded inertial electrostatic confinement device has been investigated experimentally, using a differential emissive probe and potential traces as primary diagnostics. Large amplitude oscillations in the plasma current and plasma potential were observed within a microsecond of the discharge onset, which are indicative of coherent ion oscillations about a temporarily confined excess of recirculating electron space charge. The magnitude of the depth of the potential well in the established virtual cathode was determined using a differential emissive Langmuir probe, which correlated well to the potential well inferred from the ion oscillation frequency for both hydrogen and argon experiments. It was found that the timescale for ion oscillation dispersion is strongly dependent on the neutral gas density, and weakly dependent on the peak anode voltage. The cessation of the oscillations was found to be due to charge exchange processes converting ions to high velocity neutrals, causing the abrupt de-coherence of the oscillations through an avalanche dispersion in phase space.

  16. Excitation of voltage oscillations in an induction voltage adder

    Directory of Open Access Journals (Sweden)

    Nichelle Bruner

    2009-07-01

    Full Text Available 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.

  17. Building and Managing Electronic Resources in Digital Era in India with Special Reference to IUCAA and NIV, Pune: A Comparative Case Study

    Science.gov (United States)

    Sahu, H. K.; Singh, S. N.

    2015-04-01

    This paper discusses and presents a comparative case study of two libraries in Pune, India, Inter-University Centre for Astronomy and Astrophysics and Information Centre and Library of National Institute of Virology (Indian Council of Medical Research). It compares how both libraries have managed their e-resource collections, including acquisitions, subscriptions, and consortia arrangements, while also developing a collection of their own resources, including pre-prints and publications, video lectures, and other materials in an institutional repository. This study illustrates how difficult it is to manage electronic resources in a developing country like India, even though electronic resources are used more than print resources. Electronic resource management can be daunting, but with a systematic approach, various problems can be solved, and use of the materials will be enhanced.

  18. Generalized oscillator strengths for some higher valence-shell excitations of krypton atom

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The valence-shell excitations of krypton atom have been investigated by fast electron impact with an angle-resolved electron-energy-loss spectrometer. The generalized oscillator strengths for some higher mixed valence-shell excitations in 4d, 4f, 5p, 5d, 6s, 6p, 7s ← 4p of krypton atom have been determined. Their profiles are discussed, and the generalized oscillator strengths for the electric monopole and quadrupole excitations in 5p ← 4p are compared with the calculations of Amusia et al. (Phys. Rev. A 67 022703 (2003)). The differences between the experimental results and theoretical calculations show that more studies are needed.

  19. Recent progress in the performances of ultrastable quartz resonators and oscillators

    Directory of Open Access Journals (Sweden)

    Salzenstein Patrice

    2016-01-01

    Full Text Available Stressed compensated (SC cut led recently to the best frequency stability ever obtained with a quartz oscillator, 2.5 × 10−14 for the flicker frequency modulation (FFM floor. This result is confirmed in this paper with a 3.2 × 10−14 ± 1.1 × 10−14. The quartz resonator is integrated in a 5 MHz enhanced aging box double oven controlled oscillator. After reminding a bit of history, this paper describes how the first significant development in terms of ultra-stable quartz state-of-the-art oscillators was performed in the last 20 years, how the resonators were chosen, and main information about the development of adequate electronics and how to mechanically and thermally stabilized such an ultra-stable oscillator. We also present how to characterize the expected performances, and hot topics in quartz based oscillators.

  20. Magnetic field mediated conductance oscillation in graphene p–n junctions

    Science.gov (United States)

    Cheng, Shu-Guang

    2018-04-01

    The electronic transport of graphene p–n junctions under perpendicular magnetic field is investigated in theory. Under low magnetic field, the transport is determined by the resonant tunneling of Landau levels and conductance versus magnetic field shows a Shubnikov–de Haas oscillation. At higher magnetic field, the p–n junction subjected to the quasi-classical regime and the formation of snake states results in periodical backscattering and transmission as magnetic field varies. The conductance oscillation pattern is mediated both by magnetic field and the carrier concentration on bipolar regions. For medium magnetic field between above two regimes, the combined contributions of resonant tunneling, snake states oscillation and Aharanov–Bohm interference induce irregular oscillation of conductance. At very high magnetic field, the system is subjected to quantum Hall regime. Under disorder, the quantum tunneling at low magnetic field is slightly affected and the oscillation of snake states at higher magnetic field is suppressed. In the quantum Hall regime, the conductance is a constant as predicted by the mixture rule.

  1. Cyclotron resonance for electrons over helium in resonator

    CERN Document Server

    Shikin, V B

    2002-01-01

    The problem on the cyclotron resonance (CR) for electrons on the helium film, positioned in the resonator lower part, is solved. It is shown, that it relates to one of the examples of the known problem on the oscillations of the coupled oscillators system. The coupling constant between these oscillators constituting the variable function of the problem parameters. It is minimal in the zero magnetic field and reaches its maximum under the resonance conditions, when the cyclotron frequency coincides with one of the resonator modes. The CR details of the Uhf CR-energy absorption coupled by the electrons + resonator system, are calculated. The applications of the obtained results to the available CR experiments for electrons over helium

  2. Solar opacities constrained by solar neutrinos and solar oscillations

    International Nuclear Information System (INIS)

    Cox, A.N.

    1989-01-01

    This review discusses the current situation for opacities at the solar center, the solar surface, and for the few million kelvin temperatures that occur below the convection zone. The solar center conditions are important because they are crucial for the neutrino production, which continues to be predicted about 4 times that observed. The main extinction effects there are free-free photon absorption in the electric fields of the hydrogen, helium and the CNO atoms, free electron scattering of photons, and the bound-free and bound-bound absorption of photons by iron atoms with two electrons in the 1s bound level. An assumption that the iron is condensed-out below the convection zone, and the opacity in the central regions is thereby reduced, results in about a 25 percent reduction in the central opacity but only a 5 percent reduction at the base of the convection zone. Furthermore, the p-mode solar oscillations are changed with this assumption, and do not fit the observed ones as well as for standard models. A discussion of the large effective opacity reduction by weakly interacting massive particles also results in poor agreement with observed p-mode oscillation frequencies. The much larger opacities for the solar surface layers from the Los Alamos Astrophysical Opacity Library instead of the widely used Cox and Tabor values show small improvements in oscillation frequency predictions, but the largest effect is in the discussion of p-mode stability. Solar oscillation frequencies can serve as an opacity experiment for the temperatures and densities, respectively, of a few million kelvin and between 0.1 and 10 g/cm 3 . Current oscillation frequency calculations indicate that possibly the Opacity Library values need an increase of typically 15 percent just at the bottom of the convection zone at 3 x 10 6 K. 41 refs., 15 figs., 1 tab

  3. Comparative analysis of gyrotron backward-wave oscillators operating at different cyclotron harmonics

    International Nuclear Information System (INIS)

    Yeh, Y.S.; Chang, T.H.; Wu, T.S.

    2004-01-01

    A comparative analysis between the fundamental and second cyclotron harmonics of gyrotron backward-wave oscillators (gyro-BWOs) is presented. The simulation results reveal that nonlinear field contraction is a common feature for both harmonic interactions. Besides, the electron transit angle, used to characterize the axial modes of the fundamental harmonic TE 11 mode at the start-oscillation conditions, is found to be applicable even for the second harmonic TE 21 mode. Each axial mode of either the fundamental harmonic TE 11 or the second harmonic TE 21 modes is maintained at a constant value of the electron transit angle while changing the operating parameters, such as magnetic field and beam voltage. Extensive numerical calculations are conducted for the start-oscillation currents and tuning properties. Moreover, single-mode operating regimes are suggested where the second harmonic TE 21 gyro-BWO could generate a considerable output power, comparing with the fundamental harmonic TE 11 gyro-BWO

  4. Investigation of a free electron laser oscillator in the X-ray wavelength regime for the European XFEL; Untersuchungen zu einem Freie-Elektronen-Laser-Oszillator im Roentgen-Wellenlaengenbereich fuer den European XFEL

    Energy Technology Data Exchange (ETDEWEB)

    Zemella, Johann Christian Uwe

    2013-09-15

    In this thesis an X-ray free electron laser oscillator for the European XFEL is described. Such an oscillator consists of at least two Bragg deflecting crystals, in this content two or four Diamond crystals, focussing mirrors and an undulator. The advantage of Diamond is caused by the high reflectivity and the high thermal conductivity, which is necessary for dissipate the absorbed energy out of the center of the crystal. In context of this thesis the principle layout of an XFELO for the European XFEL and the FEL process is presented. Effects on the FEL process due to the disturbances of the electron beam or the XFELO cavity are discussed. As second aspect the thermal evolution in the crystal under absorbed XFELO-pulses is investigated. An experiment for the investigation of the thermal evolution of crystals under simulated XFELO conditions is presented.

  5. Quantum Transport in Solids: Bloch Dynamics and Role of Oscillating Fields

    National Research Council Canada - National Science Library

    Kim, Ki

    1997-01-01

    .... The specific areas of research are those of Bloch electron dynamics, quantum transport in oscillating electric fields or in periodic potentials, and the capacitive nature of atomic size structures...

  6. Bipolaron assisted Bloch-like oscillations in organic lattices

    International Nuclear Information System (INIS)

    Ribeiro, Luiz Antonio; Ferreira da Cunha, Wiliam; Magela e Silva, Geraldo

    2017-01-01

    The transport of a dissociated bipolaron in organic one-dimensional lattices is theoretically investigated in the scope of a tight-binding model that includes electron-lattice interactions and an external electric field. Remarkably, the results point to a physical picture in which the dissociated bipolaron propagates as a combined state of two free-like electrons that coherently perform spatial Bloch oscillations (BO) above a critical field strength. It was also obtained that the BO's trajectory presents a net forward motion in the direction of the applied electric field. The impact of dynamical disorder in the formation of electronic BOs is determined.

  7. Bipolaron assisted Bloch-like oscillations in organic lattices

    Science.gov (United States)

    Ribeiro, Luiz Antonio; Ferreira da Cunha, Wiliam; Magela e Silva, Geraldo

    2017-06-01

    The transport of a dissociated bipolaron in organic one-dimensional lattices is theoretically investigated in the scope of a tight-binding model that includes electron-lattice interactions and an external electric field. Remarkably, the results point to a physical picture in which the dissociated bipolaron propagates as a combined state of two free-like electrons that coherently perform spatial Bloch oscillations (BO) above a critical field strength. It was also obtained that the BO's trajectory presents a net forward motion in the direction of the applied electric field. The impact of dynamical disorder in the formation of electronic BOs is determined.

  8. Bipolaron assisted Bloch-like oscillations in organic lattices

    Energy Technology Data Exchange (ETDEWEB)

    Ribeiro, Luiz Antonio, E-mail: ribeirojr@unb.br [International Center for Condensed Matter Physics, University of Brasília, P.O. Box 04531, 70.919-970, Brasília, DF (Brazil); University of Brasília, UnB Faculty of Planaltina, 73.345-010, Planaltina, DF (Brazil); Ferreira da Cunha, Wiliam; Magela e Silva, Geraldo [Institute of Physics, University of Brasília, 70.919-970, Brasília (Brazil)

    2017-06-15

    The transport of a dissociated bipolaron in organic one-dimensional lattices is theoretically investigated in the scope of a tight-binding model that includes electron-lattice interactions and an external electric field. Remarkably, the results point to a physical picture in which the dissociated bipolaron propagates as a combined state of two free-like electrons that coherently perform spatial Bloch oscillations (BO) above a critical field strength. It was also obtained that the BO's trajectory presents a net forward motion in the direction of the applied electric field. The impact of dynamical disorder in the formation of electronic BOs is determined.

  9. Start-Up of FEL Oscillator from Shot Noise

    International Nuclear Information System (INIS)

    Kumar, V.; Krishnagopal, S.; Fawley, W.M.

    2007-01-01

    In free-electron laser (FEL) oscillators, as in self-amplified spontaneous emission (SASE) FELs, the buildup of cavity power starts from shot noise resulting from the discreteness of electronic charge. It is important to do the start-up analysis for the build-up of cavity power in order to fix the macropulse width from the electron accelerator such that the system reaches saturation. In this paper, we use the time-dependent simulation code GINGER [1]to perform this analysis. We present results of this analysis for the parameters of the Compact Ultrafast TErahertz FEL (CUTE-FEL) [2] being built at RRCAT

  10. Present and future oscillation experiments at reactors

    International Nuclear Information System (INIS)

    Mikaehlyan, L.A.

    2001-01-01

    A report is presented on recent progress and developments (since the NANP'99 Conference) in the current and future long baseline (∼100 - 800 km) oscillation experiments at reactors. These experiments, under certain assumptions, can fully reconstruct the internal mass structure of the electron neutrino and provide a laboratory test of solar and atmospheric neutrino problems

  11. Time domain oscillating poles: Stability redefined in Memristor based Wien-oscillators

    KAUST Repository

    Talukdar, Abdul Hafiz Ibne

    2012-07-28

    Traditionally, the necessary and sufficient condition for any system to be oscillating is that its poles are located on the imaginary (jω) axis. In this paper, for the first time, we have shown that systems can oscillate with time-domain oscillating poles. The idea is verified using a Memristor based Wien oscillator. Sustained oscillations are observed without having the poles of the system fixed on the imaginary axis and the oscillating behavior of the system poles is reported. The oscillating resistance and triangular shape of FFT are also demonstrated with mathematical reasoning and simulation results to support the unusual and surprising characteristics. © 2009 IEEE.

  12. Nature's Autonomous Oscillators

    Science.gov (United States)

    Mayr, H. G.; Yee, J.-H.; Mayr, M.; Schnetzler, R.

    2012-01-01

    Nonlinearity is required to produce autonomous oscillations without external time dependent source, and an example is the pendulum clock. The escapement mechanism of the clock imparts an impulse for each swing direction, which keeps the pendulum oscillating at the resonance frequency. Among nature's observed autonomous oscillators, examples are the quasi-biennial oscillation and bimonthly oscillation of the Earth atmosphere, and the 22-year solar oscillation. The oscillations have been simulated in numerical models without external time dependent source, and in Section 2 we summarize the results. Specifically, we shall discuss the nonlinearities that are involved in generating the oscillations, and the processes that produce the periodicities. In biology, insects have flight muscles, which function autonomously with wing frequencies that far exceed the animals' neural capacity; Stretch-activation of muscle contraction is the mechanism that produces the high frequency oscillation of insect flight, discussed in Section 3. The same mechanism is also invoked to explain the functioning of the cardiac muscle. In Section 4, we present a tutorial review of the cardio-vascular system, heart anatomy, and muscle cell physiology, leading up to Starling's Law of the Heart, which supports our notion that the human heart is also a nonlinear oscillator. In Section 5, we offer a broad perspective of the tenuous links between the fluid dynamical oscillators and the human heart physiology.

  13. Electron temperature fluctuation in the HT-7 tokamak plasma observed by electron cyclotron emission imaging

    International Nuclear Information System (INIS)

    Xiao-Yuan, Xu; Jun, Wang; Yi, Yu; Yi-Zhi, Wen; Chang-Xuan, Yu; Wan-Dong, Liu; Bao-Nian, Wan; Xiang, Gao; Luhmann, N. C.; Domier, C. W.; Wang, Jian; Xia, Z. G.; Shen, Zuowei

    2009-01-01

    The fluctuation of the electron temperature has been measured by using the electron cyclotron emission imaging in the Hefei Tokamak-7 (HT-7) plasma. The electron temperature fluctuation with a broadband spectrum shows that it propagates in the electron diamagnetic drift direction, and the mean poloidal wave-number k-bar θ is calculated to be about 1.58 cm −1 , or k-bar θρ s thickapprox 0.34. It indicates that the fluctuation should come from the electron drift wave turbulence. The linear global scaling of the electron temperature fluctuation with the gradient of electron temperature is consistent with the mixing length scale qualitatively. Evolution of spectrum of the fluctuation during the sawtooth oscillation phases is investigated, and the fluctuation is found to increase with the gradient of electron temperature increasing during most phases of the sawtooth oscillation. The results indicate that the electron temperature gradient is probably the driver of the fluctuation enhancement. The steady heat flux driven by electron temperature fluctuation is estimated and compared with the results from power balance estimation. (fluids, plasmas and electric discharges)

  14. Early Oscillation Detection for DC/DC Converter Fault Diagnosis

    Science.gov (United States)

    Wang, Bright L.

    2011-01-01

    The electrical power system of a spacecraft plays a very critical role for space mission success. Such a modern power system may contain numerous hybrid DC/DC converters both inside the power system electronics (PSE) units and onboard most of the flight electronics modules. One of the faulty conditions for DC/DC converter that poses serious threats to mission safety is the random occurrence of oscillation related to inherent instability characteristics of the DC/DC converters and design deficiency of the power systems. To ensure the highest reliability of the power system, oscillations in any form shall be promptly detected during part level testing, system integration tests, flight health monitoring, and on-board fault diagnosis. The popular gain/phase margin analysis method is capable of predicting stability levels of DC/DC converters, but it is limited only to verification of designs and to part-level testing on some of the models. This method has to inject noise signals into the control loop circuitry as required, thus, interrupts the DC/DC converter's normal operation and increases risks of degrading and damaging the flight unit. A novel technique to detect oscillations at early stage for flight hybrid DC/DC converters was developed.

  15. High Temperature Capacitive Pressure Sensor Employing a SiC Based Ring Oscillator

    Science.gov (United States)

    Meredith, Roger D.; Neudeck, Philip G.; Ponchak, George E.; Beheim, Glenn M.; Scardelletti, Maximilian; Jordan, Jennifer L.; Chen, Liang-Yu; Spry, David J.; Krawowski, Michael J.; Hunter, Gary W.

    2011-01-01

    In an effort to develop harsh environment electronic and sensor technologies for aircraft engine safety and monitoring, we have used capacitive-based pressure sensors to shift the frequency of a SiC-electronics-based oscillator to produce a pressure-indicating signal that can be readily transmitted, e.g. wirelessly, to a receiver located in a more benign environment. Our efforts target 500 C, a temperature well above normal operating conditions of commercial circuits but within areas of interest in aerospace engines, deep mining applications and for future missions to the Venus atmosphere. This paper reports for the first time a ring oscillator circuit integrated with a capacitive pressure sensor, both operating at 500 C. This demonstration represents a significant step towards a wireless pressure sensor that can operate at 500 C and confirms the viability of 500 C electronic sensor systems.

  16. Oscillations in the spectrum of nonlinear Thomson-backscattered radiation

    Directory of Open Access Journals (Sweden)

    C. A. Brau

    2004-02-01

    Full Text Available When an electron beam collides with a high-intensity laser beam, the spectrum of the nonlinear Thomson scattering in the backward direction shows strong oscillations like those in the spectrum of an optical klystron. Laser gain on the backward Thomson scattering is estimated using the Madey theorem, and the results suggest that Thomson-backscatter free-electron lasers are possible at wavelengths extending to the far uv using a terawatt laser beam from a chirped-pulse amplifier and a high-brightness electron beam from a needle cathode.

  17. [Use of internet and electronic resources among Spanish intensivist physicians. First national survey].

    Science.gov (United States)

    Gómez-Tello, V; Latour-Pérez, J; Añón Elizalde, J M; Palencia-Herrejón, E; Díaz-Alersi, R; De Lucas-García, N

    2006-01-01

    Estimate knowledge and use habits of different electronic resources in a sample of Spanish intensivists: Internet, E-mail, distribution lists, and use of portable electronic devices. Self-applied questionnaire. A 50-question questionnaire was distributed among Spanish intensivists through the hospital marketing delegates of a pharmaceutical company and of electronic forums. A total of 682 questionnaires were analyzed (participation: 74%). Ninety six percent of those surveyed used Internet individually: 67% admitted training gap. Internet was the second source of clinical consultations most used (61%), slightly behind consultation to colleagues (65%). The pages consulted most were bibliographic databases (65%) and electronic professional journals (63%), with limited use of Evidence Based Medicine pages (19%). Ninety percent of those surveyed used e-mail regularly in the practice of their profession, although 25% admitted that were not aware of its possibilities. The use of E-mail decreased significantly with increase in age. A total of 62% of the intensivists used distribution lists. Of the rest, 42% were not aware of its existence and 32% admitted they had insufficient training to handle them. Twenty percent of those surveyed had portable electronic devices and 64% considered it useful, basically due to its rapid consultation at bedside. Female gender was a negative predictive factor of its use (OR 0.35; 95% CI 0.2-0.63; p=0.0002). A large majority of the Spanish intensivists use Internet and E-mail. E-mail lists and use of portable devices are still underused resources. There are important gaps in training and infrequent use of essential pages. There are specific groups that require directed educational policies.

  18. Time domain oscillating poles: Stability redefined in Memristor based Wien-oscillators

    KAUST Repository

    Talukdar, Abdul Hafiz Ibne; Radwan, Ahmed G.; Salama, Khaled N.

    2012-01-01

    poles. The idea is verified using a Memristor based Wien oscillator. Sustained oscillations are observed without having the poles of the system fixed on the imaginary axis and the oscillating behavior of the system poles is reported. The oscillating

  19. Model of e-learning with electronic educational resources of new generation

    OpenAIRE

    A. V. Loban; D. A. Lovtsov

    2017-01-01

    Purpose of the article: improving of scientific and methodical base of the theory of the е-learning of variability. Methods used: conceptual and logical modeling of the е-learning of variability process with electronic educational resource of new generation and system analysis of the interconnection of the studied subject area, methods, didactics approaches and information and communication technologies means. Results: the formalization complex model of the е-learning of variability with elec...

  20. Photoinduced High-Frequency Charge Oscillations in Dimerized Systems

    Science.gov (United States)

    Yonemitsu, Kenji

    2018-04-01

    Photoinduced charge dynamics in dimerized systems is studied on the basis of the exact diagonalization method and the time-dependent Schrödinger equation for a one-dimensional spinless-fermion model at half filling and a two-dimensional model for κ-(bis[ethylenedithio]tetrathiafulvalene)2X [κ-(BEDT-TTF)2X] at three-quarter filling. After the application of a one-cycle pulse of a specifically polarized electric field, the charge densities at half of the sites of the system oscillate in the same phase and those at the other half oscillate in the opposite phase. For weak fields, the Fourier transform of the time profile of the charge density at any site after photoexcitation has peaks for finite-sized systems that correspond to those of the steady-state optical conductivity spectrum. For strong fields, these peaks are suppressed and a new peak appears on the high-energy side, that is, the charge densities mainly oscillate with a single frequency, although the oscillation is eventually damped. In the two-dimensional case without intersite repulsion and in the one-dimensional case, this frequency corresponds to charge-transfer processes by which all the bonds connecting the two classes of sites are exploited. Thus, this oscillation behaves as an electronic breathing mode. The relevance of the new peak to a recently found reflectivity peak in κ-(BEDT-TTF)2X after photoexcitation is discussed.

  1. How do the multiple large-scale climate oscillations trigger extreme precipitation?

    Science.gov (United States)

    Shi, Pengfei; Yang, Tao; Xu, Chong-Yu; Yong, Bin; Shao, Quanxi; Li, Zhenya; Wang, Xiaoyan; Zhou, Xudong; Li, Shu

    2017-10-01

    Identifying the links between variations in large-scale climate patterns and precipitation is of tremendous assistance in characterizing surplus or deficit of precipitation, which is especially important for evaluation of local water resources and ecosystems in semi-humid and semi-arid regions. Restricted by current limited knowledge on underlying mechanisms, statistical correlation methods are often used rather than physical based model to characterize the connections. Nevertheless, available correlation methods are generally unable to reveal the interactions among a wide range of climate oscillations and associated effects on precipitation, especially on extreme precipitation. In this work, a probabilistic analysis approach by means of a state-of-the-art Copula-based joint probability distribution is developed to characterize the aggregated behaviors for large-scale climate patterns and their connections to precipitation. This method is employed to identify the complex connections between climate patterns (Atlantic Multidecadal Oscillation (AMO), El Niño-Southern Oscillation (ENSO) and Pacific Decadal Oscillation (PDO)) and seasonal precipitation over a typical semi-humid and semi-arid region, the Haihe River Basin in China. Results show that the interactions among multiple climate oscillations are non-uniform in most seasons and phases. Certain joint extreme phases can significantly trigger extreme precipitation (flood and drought) owing to the amplification effect among climate oscillations.

  2. Impact of Knowledge Resources Linked to an Electronic Health Record on Frequency of Unnecessary Tests and Treatments

    Science.gov (United States)

    Goodman, Kenneth; Grad, Roland; Pluye, Pierre; Nowacki, Amy; Hickner, John

    2012-01-01

    Introduction: Electronic knowledge resources have the potential to rapidly provide answers to clinicians' questions. We sought to determine clinicians' reasons for searching these resources, the rate of finding relevant information, and the perceived clinical impact of the information they retrieved. Methods: We asked general internists, family…

  3. Periodic auroral forms and geomagnetic field oscillations in the 1400 MLT region

    International Nuclear Information System (INIS)

    Potemra, T.A.; Vo, H.; Venkatesan, D.; Cogger, L.L.; Erlandson, R.E.; Zanetti, L.J.; Bythrow, P.F.; Anderson, B.J.

    1990-01-01

    The UV images obtained with the Viking satellite often show bright features which resemble beads or pearls aligned in the east-west direction between noon and 1800 MLT. Viking acquired a series of 25 UV images during a 28-min period on July 29, 1986, which showed a distinct series of periodic bright features in this region. Magnetic field and hot plasma measurements obtained by Viking confirm that the UV emissions are colocated with the field line projection of an upward-flowing region 1 Birkeland current and precipitating energetic (∼200 eV) electrons. The magnetic field and electric field measurements show transverse oscillations with a nearly constant period of about 3.5 min from 67 degree invariant latitude equatorward up to the location of the large-scale Birkeland current system near 76 degree invariant latitude. The electric field oscillations lead the magnetic field oscillations by about a quarter-period. The authors interpret the observed oscillations as standing Alfven waves driven at a frequency near the local resonance frequency by a large-scale wave in the boundary layer. They propose that the energy flux of the precipitating low-energy electrons in this afternoon region is modulated by this boundary wave and produces the periodic UV emission features. The results of this study support the view that large-scale oscillations of magnetospheric boundaries, possibly associated with the Kelvin-Helmholtz instability, can modulate currents, particles, and auroral forms

  4. Starting electronics all you need to get a grounding in practical electronics

    CERN Document Server

    Brindley, Keith

    2013-01-01

    Starting Electronics is a nine-chapter introductory text to electronics based on feature articles previously published as magazine articles. The opening chapter provides an overview of the fundamentals of electronics. The succeeding chapters present details of some easy-to-do experiments and the current and voltage measurement. The remaining chapters cover some basic components of electronics, including capacitor, integrated circuit, oscillator, filter, diodes, and transistors. This book will prove useful to electronic constructors and students.

  5. Electronic Document Management: A Human Resource Management Case Study

    Directory of Open Access Journals (Sweden)

    Thomas Groenewald

    2004-11-01

    Full Text Available This case study serve as exemplar regarding what can go wrong with the implementation of an electronic document management system. Knowledge agility and knowledge as capital, is outlined against the backdrop of the information society and knowledge economy. The importance of electronic document management and control is sketched thereafter. The literature review is concluded with the impact of human resource management on knowledge agility, which includes references to the learning organisation and complexity theory. The intervention methodology, comprising three phases, follows next. The results of the three phases are presented thereafter. Partial success has been achieved with improving the human efficacy of electronic document management, however the client opted to discontinue the system in use. Opsomming Die gevalle studie dien as voorbeeld van wat kan verkeerd loop met die implementering van ’n elektroniese dokumentbestuur sisteem. Teen die agtergrond van die inligtingsgemeenskap en kennishuishouding word kennissoepelheid en kennis as kapitaal bespreek. Die literatuurstudie word afgesluit met die inpak van menslikehulpbronbestuur op kennissoepelheid, wat ook die verwysings na die leerorganisasie en kompleksietydsteorie insluit. Die metodologie van die intervensie, wat uit drie fases bestaan, volg daarna. Die resultate van die drie fases word vervolgens aangebied. Slegs gedeelte welslae is behaal met die verbetering van die menslike doeltreffendheid ten opsigte van elektroniese dokumentbestuur. Die klient besluit egter om nie voort te gaan om die huidige sisteem te gebruik nie.

  6. Saturation and oscillation of current in semiconductors subjected to uniaxial deformation

    International Nuclear Information System (INIS)

    Zdebskii, A.P.; Olikh, Yu.A.; Savchuk, A.U.

    1985-01-01

    The influence of an external uniaxial deformation on the saturation and oscillations of current in photosensitive CdS monocrystals is investigated. The specimens were subjected to uniaxial pressure up to 6 x 10 7 N/m 2 , the pressure being either parallel or perpendicular to the c axis in CdS. With application of external pressure, the shape of current oscillations and their amplitude changed. In the case where the pressure was perpendicular to the direction of current I, the amplitude of oscillations and the saturation depth of the volt-ampere characteristic, VAC, were increased. With pressure being parallel to the current direction, the reverse phenomenon was observed, i.e. the efficiency of the acousto-electronic interaction was reduced

  7. One dimension harmonic oscillator

    International Nuclear Information System (INIS)

    Cohen-Tannoudji, Claude; Diu, Bernard; Laloe, Franck.

    1977-01-01

    The importance of harmonic oscillator in classical and quantum physics, eigenvalues and eigenstates of hamiltonian operator are discussed. In complement are presented: study of some physical examples of harmonic oscillators; study of stationnary states in the /x> representation; Hermite polynomials; resolution of eigenvalue equation of harmonic oscillator by polynomial method; isotope harmonic oscillator with three dimensions; charged harmonic oscillator in uniform electric field; quasi classical coherent states of harmonic oscillator; eigenmodes of vibration of two coupled harmonic oscillators; vibration modus of a continuous physical system (application to radiation: photons); vibration modus of indefinite linear chain of coupled harmonic oscillators (phonons); one-dimensional harmonic oscillator in thermodynamic equilibrium at temperature T [fr

  8. Energy measurements from betatron oscillations

    International Nuclear Information System (INIS)

    Himel, T.; Thompson, K.

    1989-03-01

    In the Stanford Linear Collider the electron beam is accelerated from 1--50 GeV in a distance of 3 km. The energy is measured and corrected at the end with an energy feedback loop. There are no bends within the linear accelerator itself, so no intermediate energy measurements are made. Errors in the energy profile due to mis-phasing of the rf, or due to calibration errors in the klystrons' rf outputs are difficult to detect. As the total betatron phase advance down the accelerator is about 30 /times/ 2π, an energy error of a few percent can cause a large error in the total phase advance. This in turn degrades the performance of auto-steering programs. We have developed a diagnostic program which generates and measures several betatron oscillations in the accelerator. It then analyzes this oscillation, looking for frequency changes which indicate energy errors. One can then compensate for or correct these energy errors. 6 refs., 1 fig

  9. Synchronizing a single-electron shuttle to an external drive

    Science.gov (United States)

    Moeckel, Michael J.; Southworth, Darren R.; Weig, Eva M.; Marquardt, Florian

    2014-04-01

    The nanomechanical single-electron shuttle is a resonant system in which a suspended metallic island oscillates between and impacts at two electrodes. This setup holds promise for one-by-one electron transport and the establishment of an absolute current standard. While the charge transported per oscillation by the nanoscale island will be quantized in the Coulomb blockade regime, the frequency of such a shuttle depends sensitively on many parameters, leading to drift and noise. Instead of considering the nonlinearities introduced by the impact events as a nuisance, here we propose to exploit the resulting nonlinear dynamics to realize a highly precise oscillation frequency via synchronization of the shuttle self-oscillations to an external signal. We link the established phenomenological description of synchronization based on the Adler equation to the microscopic nonlinear dynamics of the electron shuttle by calculating the effective Adler constant analytically in terms of the microscopic parameters.

  10. Synchronizing a single-electron shuttle to an external drive

    International Nuclear Information System (INIS)

    Moeckel, Michael J; Southworth, Darren R; Weig, Eva M; Marquardt, Florian

    2014-01-01

    The nanomechanical single-electron shuttle is a resonant system in which a suspended metallic island oscillates between and impacts at two electrodes. This setup holds promise for one-by-one electron transport and the establishment of an absolute current standard. While the charge transported per oscillation by the nanoscale island will be quantized in the Coulomb blockade regime, the frequency of such a shuttle depends sensitively on many parameters, leading to drift and noise. Instead of considering the nonlinearities introduced by the impact events as a nuisance, here we propose to exploit the resulting nonlinear dynamics to realize a highly precise oscillation frequency via synchronization of the shuttle self-oscillations to an external signal. We link the established phenomenological description of synchronization based on the Adler equation to the microscopic nonlinear dynamics of the electron shuttle by calculating the effective Adler constant analytically in terms of the microscopic parameters

  11. The role of inelastic processes in the temperature dependence of hall induced resistance oscillations

    International Nuclear Information System (INIS)

    Kunold, Alejandro; Torres, Manuel

    2013-01-01

    We develop a model of magnetoresistance oscillations induced by the Hall field in order to study the temperature dependence observed in recent experiments in two dimensional electron systems. The model is based on the solution of the von Neumann equation incorporating the exact dynamics of two-dimensional damped electrons in the presence of arbitrarily strong magnetic and dc electric fields, while the effects of randomly distributed neutral and charged impurities are perturbatively added. Both the effects of elastic impurity scattering as well as those related to inelastic processes play an important role. The theoretical predictions correctly reproduce the experimentally observed oscillations amplitude, provided that the quantum inelastic scattering rate obeys a T 2 temperature dependence, consistent with electron–electron interaction effects

  12. New results from the T2K neutrino oscillation experiment

    Energy Technology Data Exchange (ETDEWEB)

    Oser, Scott M., E-mail: oser@phas.ubc.ca [University of British Columbia, Department of Physics and Astronomy (Canada); Collaboration: T2K Collaboration

    2013-03-15

    The T2K experiment searches for the appearance of electron neutrinos in a muon neutrino beam. The rate of this process is sensitive to the neutrino mixing parameter {theta}{sub 13}. Recent measurements that {theta}{sub 13} {ne} 0 imply that {nu}{sub {mu}} {yields} {nu}{sub e} oscillations should be observable. Using all data through May 15, 2012 the T2K experiment has detected 10 candidate {nu}{sub e} events, with an expected background for {theta}{sub 13} = 0 of 2.73{+-}0.37 events. This 3.2{sigma} excess of {nu}{sub e} events is the strongest indication to date for appearance of electron neutrinos in a neutrino oscillation experiment, and for normal mass hierarchy and {delta}{sub CP} = 0 yields 0.059 < sin{sup 2} 2{theta}{sub 13} < 0.164 at the 68 % C.L.

  13. Linear theory of plasma filled backward wave oscillator

    Indian Academy of Sciences (India)

    An analytical and numerical study of backward wave oscillator (BWO) in linear regime is presented to get an insight into the excitation of electromagnetic waves as a result of the interaction of the relativistic electron beam with a slow wave structure. The effect of background plasma on the BWO instability is also presented.

  14. Challenges in the implementation of an electronic surveillance system in a resource-limited setting: Alerta, in Peru

    Directory of Open Access Journals (Sweden)

    Soto Giselle

    2008-11-01

    Full Text Available Abstract Background Infectious disease surveillance is a primary public health function in resource-limited settings. In 2003, an electronic disease surveillance system (Alerta was established in the Peruvian Navy with support from the U.S. Naval Medical Research Center Detachment (NMRCD. Many challenges arose during the implementation process, and a variety of solutions were applied. The purpose of this paper is to identify and discuss these issues. Methods This is a retrospective description of the Alerta implementation. After a thoughtful evaluation according to the Centers for Disease Control and Prevention (CDC guidelines, the main challenges to implementation were identified and solutions were devised in the context of a resource-limited setting, Peru. Results After four years of operation, we have identified a number of challenges in implementing and operating this electronic disease surveillance system. These can be divided into the following categories: (1 issues with personnel and stakeholders; (2 issues with resources in a developing setting; (3 issues with processes involved in the collection of data and operation of the system; and (4 issues with organization at the central hub. Some of the challenges are unique to resource-limited settings, but many are applicable for any surveillance system. For each of these challenges, we developed feasible solutions that are discussed. Conclusion There are many challenges to overcome when implementing an electronic disease surveillance system, not only related to technology issues. A comprehensive approach is required for success, including: technical support, personnel management, effective training, and cultural sensitivity in order to assure the effective deployment of an electronic disease surveillance system.

  15. Transfer of non-Gaussian quantum states of mechanical oscillator to light

    Science.gov (United States)

    Filip, Radim; Rakhubovsky, Andrey A.

    2015-11-01

    Non-Gaussian quantum states are key resources for quantum optics with continuous-variable oscillators. The non-Gaussian states can be deterministically prepared by a continuous evolution of the mechanical oscillator isolated in a nonlinear potential. We propose feasible and deterministic transfer of non-Gaussian quantum states of mechanical oscillators to a traveling light beam, using purely all-optical methods. The method relies on only basic feasible and high-quality elements of quantum optics: squeezed states of light, linear optics, homodyne detection, and electro-optical feedforward control of light. By this method, a wide range of novel non-Gaussian states of light can be produced in the future from the mechanical states of levitating particles in optical tweezers, including states necessary for the implementation of an important cubic phase gate.

  16. Thermionics basic principles of electronics

    CERN Document Server

    Jenkins, J; Ashhurst, W

    2013-01-01

    Basic Principles of Electronics, Volume I : Thermionics serves as a textbook for students in physics. It focuses on thermionic devices. The book covers topics on electron dynamics, electron emission, and the themionic vacuum diode and triode. Power amplifiers, oscillators, and electronic measuring equipment are studied as well. The text will be of great use to physics and electronics students, and inventors.

  17. Semiconductor lasers driven by self-sustained chaotic electronic oscillators and applications to optical chaos cryptography.

    Science.gov (United States)

    Kingni, Sifeu Takougang; Mbé, Jimmi Hervé Talla; Woafo, Paul

    2012-09-01

    In this work, we numerically study the dynamics of vertical cavity surface emitting laser (VCSEL) firstly when it is driven by Chua's oscillator, secondly in case where it is driven by a broad frequency spectral bandwidth chaotic oscillator developed by Nana et al. [Commun. Nonlinear Sci. Numer. Simul. 14, 2266 (2009)]. We demonstrated that the VCSEL generated robust chaotic dynamics compared to the ones found in VCSEL subject to a sinusoidally modulated current and therefore it is more suitable for chaos encryption techniques. The synchronization characteristics and the communication performances of unidirectional coupled VCSEL driven by the broad frequency spectral bandwidth chaotic oscillators are investigated numerically. The results show that high-quality synchronization and transmission of messages can be realized for suitable system parameters. Chaos shift keying method is successfully applied to encrypt a message at a high bitrate.

  18. Absence of quantum oscillations in electronic excitation transfer in the Fenna-Matthews-Olson complex

    Science.gov (United States)

    Eisfeld, Alexander; Ritschel, Gerhard; Roden, Jan; Strunz, Walter; Aspuru-Guzik, Alan

    2012-02-01

    Energy transfer in the photosynthetic Fenna-Matthews-Olson (FMO) complex of the Green Sulfur Bacteria is studied theoretically taking all three subunits (monomers) of the FMO trimer and the recently found eighth bacteriochlorophyll (BChl) molecule into account. For the calculations we use the efficient Non-Markovian Quantum State diffusion approach. Since it is believed that the eighth BChl is located near the main light harvesting antenna we look at the differences in transfer between the situation when BChl 8 is initially excited and the usually considered case when BChl 1 or 6 is initially excited. We find strong differences in the transfer dynamics, both qualitatively and quantitatively. When the excited state dynamics is initialized at site eight of the FMO complex, we see a slow exponential-like decay of the excitation. This is in contrast to the oscillations and a relatively fast transfer that occurs when only seven sites or initialization at sites 1 and 6 is considered. Additionally we show that differences in the values of the electronic transition energies found in the literature lead to a large difference in the transfer dynamics.

  19. Oscillator monitor

    International Nuclear Information System (INIS)

    McNeill, G.A.

    1981-01-01

    Present high-speed data acquisition systems in nuclear diagnostics use high-frequency oscillators to provide timing references for signals recorded on fast, traveling-wave oscilloscopes. An oscillator's sinusoidal wave shape is superimposed on the recorded signal with each cycle representing a fixed time increment. During data analysis the sinusoid is stripped from the signal, leaving a clean signal shape with known timing. Since all signal/time relationships are totally dependant upon working oscillators, these critical devices must have remote verification of proper operation. This manual presents the newly-developed oscillator monitor which will provide the required verification

  20. Low-power crystal and MEMS oscillators the experience of watch developments

    CERN Document Server

    Eric Vittoz

    2010-01-01

    Electronic oscillators using an electromechanical device as a frequency reference are irreplaceable components of systems-on-chip for time-keeping, carrier frequency generation and digital clock generation. With their excellent frequency stability and very large quality factor Q, quartz crystal resonators have been the dominant solution for more than 70 years. But new possibilities are now offered by micro-electro-mechanical (MEM) resonators, that have a qualitatively identical equivalent electrical circuit. Low-Power Crystal and MEMS Oscillators concentrates on the analysis and design of the most important schemes of integrated oscillator circuits. It explains how these circuits can be optimized by best exploiting the very high Q of the resonator to achieve the minimum power consumption compatible with the requirements on frequency stability and phase noise. The author has 40 years of experience in designing very low-power, high-performance quartz oscillators for watches and other battery operated systems an...

  1. Scattering of electromagnetic waves into plasma oscillations via plasma particles

    International Nuclear Information System (INIS)

    Lin, A.T.; Dawson, J.M.

    1975-01-01

    A plasma subjected to an intense electromagnetic wave can exhibit a large number of parametric instabilities. An interesting example which has received little attention is the decay of the electromagnetic wave into a plasma oscillation with the excess energy and momentum being carried off by electrons. This process has been simulated on a one-and-two-halves dimensional electromagnetic code. The incident electromagnetic wave had a frequency near the plasma frequency so that decay into a plasma oscillation and a backscattered electromagnetic wave was excluded. As expected, the threshold for this instability was very large , so it is unlikely that this instability is competitive in most laser plasmas. Nevertheless, the physical mechanism involved provides a means for absorption of laser light and acceleration of particles in a plasma containing large amplitude plasma oscillations

  2. Effects of electron beam parameters and velocity spread on radio frequency output of a photonic band gap cavity gyrotron oscillator

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Ashutosh, E-mail: asingh.rs.ece@iitbhu.ac.in [Faculty of Physical Sciences, Institute of Natural Sciences and Humanities, Shri Ramswaroop Memorial University, Lucknow-Deva Road, Uttar Pradesh 225003 (India); Center of Research in Microwave Tubes, Department of Electronics Engineering, Indian Institute of Technology (Banaras Hindu University), Varanasi 221005 (India); Jain, P. K. [Center of Research in Microwave Tubes, Department of Electronics Engineering, Indian Institute of Technology (Banaras Hindu University), Varanasi 221005 (India)

    2015-09-15

    In this paper, the effects of electron beam parameters and velocity spread on the RF behavior of a metallic photonic band gap (PBG) cavity gyrotron operating at 35 GHz with TE{sub 041}–like mode have been theoretically demonstrated. PBG cavity is used here to achieve a single mode operation of the overmoded cavity. The nonlinear time-dependent multimode analysis has been used to observe the beam-wave interaction behavior of the PBG cavity gyrotron, and a commercially available PIC code “CST Particle Studio” has been reconfigured to obtain 3D simulation results in order to validate the analytical values. The output power for this typical PBG gyrotron has been obtained ∼108 kW with ∼15.5% efficiency in a well confined TE{sub 041}–like mode, while all other competing modes have significantly low values of power output. The output power and efficiency of a gyrotron depend highly on the electron beam parameters and velocity spread. The influence of several electron beam parameters, e.g., beam voltage, beam current, beam velocity pitch factor, and DC magnetic field, on the PBG gyrotron operations has been investigated. This study would be helpful in optimising the electron beam parameters and estimating accurate RF output power of the high frequency PBG cavity based gyrotron oscillators.

  3. High electron mobility and quantum oscillations in non-encapsulated ultrathin semiconducting Bi2O2Se

    Science.gov (United States)

    Wu, Jinxiong; Yuan, Hongtao; Meng, Mengmeng; Chen, Cheng; Sun, Yan; Chen, Zhuoyu; Dang, Wenhui; Tan, Congwei; Liu, Yujing; Yin, Jianbo; Zhou, Yubing; Huang, Shaoyun; Xu, H. Q.; Cui, Yi; Hwang, Harold Y.; Liu, Zhongfan; Chen, Yulin; Yan, Binghai; Peng, Hailin

    2017-07-01

    High-mobility semiconducting ultrathin films form the basis of modern electronics, and may lead to the scalable fabrication of highly performing devices. Because the ultrathin limit cannot be reached for traditional semiconductors, identifying new two-dimensional materials with both high carrier mobility and a large electronic bandgap is a pivotal goal of fundamental research. However, air-stable ultrathin semiconducting materials with superior performances remain elusive at present. Here, we report ultrathin films of non-encapsulated layered Bi2O2Se, grown by chemical vapour deposition, which demonstrate excellent air stability and high-mobility semiconducting behaviour. We observe bandgap values of ˜0.8 eV, which are strongly dependent on the film thickness due to quantum-confinement effects. An ultrahigh Hall mobility value of >20,000 cm2 V-1 s-1 is measured in as-grown Bi2O2Se nanoflakes at low temperatures. This value is comparable to what is observed in graphene grown by chemical vapour deposition and at the LaAlO3-SrTiO3 interface, making the detection of Shubnikov-de Haas quantum oscillations possible. Top-gated field-effect transistors based on Bi2O2Se crystals down to the bilayer limit exhibit high Hall mobility values (up to 450 cm2 V-1 s-1), large current on/off ratios (>106) and near-ideal subthreshold swing values (˜65 mV dec-1) at room temperature. Our results make Bi2O2Se a promising candidate for future high-speed and low-power electronic applications.

  4. Practical microwave electron devices

    CERN Document Server

    Meurant, Gerard

    2013-01-01

    Practical Microwave Electron Devices provides an understanding of microwave electron devices and their applications. All areas of microwave electron devices are covered. These include microwave solid-state devices, including popular microwave transistors and both passive and active diodes; quantum electron devices; thermionic devices (including relativistic thermionic devices); and ferrimagnetic electron devices. The design of each of these devices is discussed as well as their applications, including oscillation, amplification, switching, modulation, demodulation, and parametric interactions.

  5. Neutrinos in the Electron

    International Nuclear Information System (INIS)

    Koschmieder, E. L.

    2007-01-01

    I will show that one half of the rest mass of the electron consists of electron neutrinos and that the other half of the rest mass of the electron consists of the mass in the energy of electric oscillations. With this composition we can explain the rest mass of the electron, its charge, its spin and its magnetic moment We have also determined the rest masses of the muon neutrino and the electron neutrino

  6. Power oscillation damping controller

    DEFF Research Database (Denmark)

    2012-01-01

    A power oscillation damping controller is provided for a power generation device such as a wind turbine device. The power oscillation damping controller receives an oscillation indicating signal indicative of a power oscillation in an electricity network and provides an oscillation damping control...

  7. Quantum oscillations in vortex-liquids

    Science.gov (United States)

    Banerjee, Sumilan; Zhang, Shizhong; Randeria, Mohit

    2012-02-01

    Motivated by observations of quantum oscillations in underdoped cuprates [1], we examine the electronic density of states (DOS) in a vortex-liquid state, where long-range phase coherence is destroyed by an external magnetic field H but the local pairing amplitude survives. We note that this regime is distinct from that studied in most of the recent theories, which have focused on either a Fermi liquid with a competing order parameter or on a d-wave vortex lattice. The cuprate experiments are very likely in a resistive vortex-liquid state. We generalize the s-wave analysis of Maki and Stephen [2] to d-wave pairing and examine various regimes of the chemical potential, gap and field. We find that the (1/H) oscillations of the DOS at the chemical potential in a d-wave vortex-liquid are much more robust, i.e., have a reduced damping, compared to the s-wave case. We critically investigate the conventional wisdom relating the observed frequency to the area of an underlying Fermi surface. We also show that the oscillations in the DOS cross over to a √H behavior in the low field limit, in agreement with the recent specific heat measurements. [1] L. Taillefer, J. Phys. Cond. Mat. 21, 164212 (2009). [2] M. J. Stephen, Phys. Rev. B 45, 5481 (1992).

  8. Electron-electron interaction in p-SiGe/Ge quantum wells

    International Nuclear Information System (INIS)

    Roessner, Benjamin; Kaenel, Hans von; Chrastina, Daniel; Isella, Giovanni; Batlogg, Bertram

    2005-01-01

    The temperature dependent magnetoresistance of high mobility p-SiGe/Ge quantum wells is studied with hole densities ranging from 1.7 to 5.9 x 10 11 cm -2 . At magnetic fields below the onset of quantum oscillations that reflect the high mobility values (up to 75000 cm 2 /Vs), we observe the clear signatures of electron-electron interaction. We compare our experiment with the theory of electron-electron interaction including the Zeeman band splitting. The observed magnetoresistance is well explained as a superposition of band structure induced positive magnetoresistance and the negative magntoresistance due to the electron-electron interaction effect

  9. An XUV/VUV free-electron laser oscillator

    Science.gov (United States)

    Goldstein, J. C.; Newnam, B. E.; Cooper, R. K.; Comly, J. C., Jr.

    Problems regarding the extension of free-electron laser technology from the visible and near infrared region, where such devices are currently operating, to the ultraviolet have recently been extensively discussed. It was found that significant technical problems must be overcome before free-electron lasers (FELs) can be operated in the VUV (100-200 nm) and the XUV (50-100). However, the present lack of other intense and tunable sources of coherent radiation at these wavelengths together with the intrinsic properties of FELs make the development of such devices potentially very rewarding. The properties of FELs include continuous tunability in wavelength and output in the form of a train of picosecond pulses. An investigation is conducted regarding the feasibility of an operation of a FEL in the XUV/VUV regions, taking into account a theoretical model. It is found that modest improvements in electron beam and optical mirror technologies will make the design of a FEL for operation in the 50-200-nm range of optical wavelength possible.

  10. Design of power oscillator for 500 keV/20 mA Cockroft-Walton high voltage supply

    International Nuclear Information System (INIS)

    Djasiman; Sudjatmoko; Suprapto

    1999-01-01

    A design of power oscillator for Cockroft-Walton high voltage supply was carried out. This high voltage supply would be used as the acceleration voltage supply of an electron beam machine designed to have 500 keV/20 mA capacity. The power oscillator design consisted of output specification, circuit diagram, power supply and oscillator main components determinations. The power oscillator output wave power, voltage and frequency designed according to voltage multiplier input requirements. The design results showed that the circuit was class-c tickler oscillator having an output specification of 12.1 kW, 15 kV and 40 kHz sinus wave. The main component was a ITK 15-2 triode tube. (author)

  11. Considering Point-of-Care Electronic Medical Resources in Lieu of Traditional Textbooks for Medical Education.

    Science.gov (United States)

    Hale, LaDonna S; Wallace, Michelle M; Adams, Courtney R; Kaufman, Michelle L; Snyder, Courtney L

    2015-09-01

    Selecting resources to support didactic courses is a critical decision, and the advantages and disadvantages must be carefully considered. During clinical rotations, students not only need to possess strong background knowledge but also are expected to be proficient with the same evidence-based POC resources used by clinicians. Students place high value on “real world” learning and therefore may place more value on POC resources that they know practicing clinicians use as compared with medical textbooks. The condensed nature of PA education requires students to develop background knowledge and information literacy skills over a short period. One way to build that knowledge and those skills simultaneously is to use POC resources in lieu of traditional medical textbooks during didactic training. Electronic POC resources offer several advantages over traditional textbooks and should be considered as viable options in PA education.

  12. Linac technology for free-electron lasers

    International Nuclear Information System (INIS)

    Cooper, R.K.; Morton, P.L.; Wilson, P.B.; Keefe, D.; Faltens, A.

    1983-01-01

    The purpose of this paper is to concentrate on the properties of high-energy electron linear accelerators for use in free-electron lasers operating principally in the Compton regime. To fix our focus somewhat, we shall consider electron energies in the 20- to 200-MeV range and consider requirements for high-power free-electron lasers operating in the 0.5- to 10-μm range. Preliminary remarks are made on high-power free-electron laser amplifiers and oscillators and some desirable characteristics of the linacs that deliver electron beams for these devices. Both the high peak-current requirements of the amplifier and the high pulse-repetition frequency requirements of the oscillator can be met by present-day linac technology, although not necessarily by the same machine. In this papers second and third section, the technology of two rather different types of linear accelerators, the rf linac and the induction linac, is reviewed. In conclusion, applications to the Free Electron Lasers are stated

  13. Investigations of sawtooth oscillations with the Greifswald EBIT

    Science.gov (United States)

    Schabinger, B.; Biedermann, C.; Gierke, S.; Marx, G.; Radtke, R.; Schweikhard, L.

    2013-03-01

    The former Berlin electron-beam ion-trap was moved to Greifswald. One of the first aims after the reinstallation was the continuation of experiments using mixed ensembles of low- and high-Z ions for further studies of the previously reported sawtooth-like oscillations of the trap plasma. First results of these studies for xenon/argon mixtures are presented.

  14. Electronics pocket book

    CERN Document Server

    Parr, E A

    1981-01-01

    Electronics Pocket Book, Fourth Edition is a nonmathematical presentation of the many varied topics covered by electronics. The book tackles electron physics, electronic components (i.e. resistors, capacitors, and conductors), integrated circuits, and the principles of a.c. and d.c. amplifiers. The text also discusses oscillators, digital circuits, digital computers, and optoelectronics (i.e., sensors, emitters, and devices that utilize light). Communications (such as line and radio communications, transmitters, receivers, and digital techniques); the principles and examples of servosystems; a

  15. Resource conservation approached with an appropriate collection and upgrade-remanufacturing for used electronic products.

    Science.gov (United States)

    Zlamparet, Gabriel I; Tan, Quanyin; Stevels, A B; Li, Jinhui

    2018-03-01

    This comparative research represents an example for a better conservation of resources by reducing the amount of waste (kg) and providing it more value under the umbrella of remanufacturing. The three discussed cases will expose three issues already addressed separately in the literature. The generation of waste electrical and electronic equipment (WEEE) interacts with the environmental depletion. In this article, we gave the examples of addressed issues under the concept of remanufacturing. Online collection opportunity eliminating classical collection, a business to business (B2B) implementation for remanufactured servers and medical devices. The material reuse (recycling), component sustainability, reuse (part harvesting), product reuse (after repair/remanufacturing) indicates the recovery potential using remanufacturing tool for a better conservation of resources adding more value to the products. Our findings can provide an overview of new system organization for the general collection, market potential and the technological advantages using remanufacturing instead of recycling of WEEE or used electrical and electronic equipment. Copyright © 2017. Published by Elsevier Ltd.

  16. Restoration of oscillation in network of oscillators in presence of direct and indirect interactions

    Energy Technology Data Exchange (ETDEWEB)

    Majhi, Soumen; Bera, Bidesh K. [Physics and Applied Mathematics Unit, Indian Statistical Institute, Kolkata-700108 (India); Bhowmick, Sourav K. [Department of Electronics, Asutosh College, Kolkata-700026 (India); Ghosh, Dibakar, E-mail: diba.ghosh@gmail.com [Physics and Applied Mathematics Unit, Indian Statistical Institute, Kolkata-700108 (India)

    2016-10-23

    The suppression of oscillations in coupled systems may lead to several unwanted situations, which requires a suitable treatment to overcome the suppression. In this paper, we show that the environmental coupling in the presence of direct interaction, which can suppress oscillation even in a network of identical oscillators, can be modified by introducing a feedback factor in the coupling scheme in order to restore the oscillation. We inspect how the introduction of the feedback factor helps to resurrect oscillation from various kinds of death states. We numerically verify the resurrection of oscillations for two paradigmatic limit cycle systems, namely Landau–Stuart and Van der Pol oscillators and also in generic chaotic Lorenz oscillator. We also study the effect of parameter mismatch in the process of restoring oscillation for coupled oscillators. - Highlights: • Amplitude death is observed using direct and indirect coupling. • Revival of oscillation using feedback parameter is discussed. • Restoration of oscillation is observed in limit cycle and chaotic systems.

  17. A 250-GHz CARM [Cyclotron Auto Resonance Maser] oscillator experiment driven by an induction linac

    International Nuclear Information System (INIS)

    Caplan, M.; Kulke, B.; Bubp, D.G.; McDermott, D.; Luhmann, N.

    1990-01-01

    A 250-GHz Cyclotron Auto Resonance Maser (CARM) oscillator has been designed and constructed and will be tested using a 1-kA, 2-MeV electron beam produced by the induction linac at the Accelerator Research Center (ARC) facility of Lawrence Livermore National Laboratory (LLNL). The oscillator circuit was made to operate in the TE 11 mode at ten times cutoff using waveguide Bragg reflectors to create an external cavity Q of 8000. Theory predicts cavity fill times of less than 30 ns (pulse length) and efficiencies approaching 20% is sufficiently low transverse electron velocity spreads are maintained (2%)

  18. Effects of the Use of Electronic Human Resource Management (EHRM Within Human Resource Management (HRM Functions at Universities

    Directory of Open Access Journals (Sweden)

    Chux Gervase Iwu

    2016-09-01

    Full Text Available This study set out to examine the effect of e-hrm systems in assisting human resource practitioners to execute their duties and responsibilities. In comparison to developed economies of the world, information technology adoption in sub-Saharan Africa has not been without certain glitches. Some of the factors that are responsible for these include poor need identification, sustainable funding, and insufficient skills. Besides these factors, there is also the issue of change management and users sticking to what they already know. Although, the above factors seem negative, there is strong evidence that information systems such as electronic human resource management present benefits to an organization. To achieve this, a dual research approach was utilized. Literature assisted immensely in both the development of the conceptual framework upon which the study hinged as well as in the development of the questionnaire items. The study also made use of an interview checklist to guide the participants. The findings reveal a mix of responses that indicate that while there are gains in adopting e-hrm systems, it is wiser to consider supporting resources as well as articulate the needs of the university better before any investment is made.

  19. Electronic human resource management: Enhancing or entrancing?

    Directory of Open Access Journals (Sweden)

    Paul Poisat

    2017-07-01

    Full Text Available Orientation: This article provides an investigation into the current level of development of the body of knowledge related to electronic human resource management (e-HRM by means of a qualitative content analysis. Several aspects of e-HRM, namely definitions of e-HRM, the theoretical perspectives around e-HRM, the role of e-HRM, the various types of e-HRM and the requirements for successful e-HRM, are examined. Research purpose: The purpose of the article was to determine the status of e-HRM and examine the studies that report on the link between e-HRM and organisational productivity. Motivation for the study: e-HRM has the capacity to improve organisational efficiency and leverage the role of human resources (HR as a strategic business partner. Main findings: The notion that the implementation of e-HRM will lead to improved organisational productivity is commonly assumed; however, empirical evidence in this regard was found to be limited. Practical/managerial implications: From the results of this investigation it is evident that more research is required to gain a greater understanding of the influence of e-HRM on organisational productivity, as well as to develop measures for assessing this influence. Contribution: This article proposes additional areas to research and measure when investigating the effectiveness of e-HRM. It provides a different lens from which to view e-HRM assessment whilst keeping it within recognised HR measurement parameters (the HR value chain. In addition, it not only provides areas for measuring e-HRM’s influence but also provides important clues as to how the measurements may be approached.

  20. Real-time combustion control and diagnostics sensor-pressure oscillation monitor

    Science.gov (United States)

    Chorpening, Benjamin T [Morgantown, WV; Thornton, Jimmy [Morgantown, WV; Huckaby, E David [Morgantown, WV; Richards, George A [Morgantown, WV

    2009-07-14

    An apparatus and method for monitoring and controlling the combustion process in a combustion system to determine the amplitude and/or frequencies of dynamic pressure oscillations during combustion. An electrode in communication with the combustion system senses hydrocarbon ions and/or electrons produced by the combustion process and calibration apparatus calibrates the relationship between the standard deviation of the current in the electrode and the amplitudes of the dynamic pressure oscillations by applying a substantially constant voltage between the electrode and ground resulting in a current in the electrode and by varying one or more of (1) the flow rate of the fuel, (2) the flow rate of the oxidant, (3) the equivalence ratio, (4) the acoustic tuning of the combustion system, and (5) the fuel distribution in the combustion chamber such that the amplitudes of the dynamic pressure oscillations in the combustion chamber are calculated as a function of the standard deviation of the electrode current. Thereafter, the supply of fuel and/or oxidant is varied to modify the dynamic pressure oscillations.

  1. Plasma-filled rippled wall rectangular backward wave oscillator

    Indian Academy of Sciences (India)

    Performance of the backward wave oscillator (BWO) is greatly enhanced with the introduction of plasma. Linear theory of the dispersion relation and the growth rate have been derived and analysed numerically for plasma-filled rippled wall rectangular waveguide driven by sheet electron beam. To see the effect of plasma ...

  2. Improvements of the ruby laser oscillator system for laser scattering

    International Nuclear Information System (INIS)

    Yamauchi, Toshihiko; Kumagai, Katsuaki; Kawakami, Tomohide; Matoba, Tohru; Funahashi, Akimasa

    1978-10-01

    A ruby laser oscillator system is used to measure electron temperatures of the Tokamak plasmas(JFT-2 and JFT-2a). Improvements have been made of the laser oscillator to obtain the correct values. Described are the improvements and the damages of a ruby rod and a KD*P crystal for Q-switching by laser beam. Improvement are the linear Xe lamp replaced by a helical Xe lamp and in the electrical circuit for Q-switching. The damage of an optical component by a laser beam should be clarified from the damage data; the cause is not found yet. (author)

  3. Breathing oscillations in enlarged cylindrical-anode-layer Hall plasma accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Geng, S. F.; Wang, C. X. [Southwestern Institute of Physics, Chengdu 610041 (China); Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China); Tang, D. L.; Qiu, X. M. [Southwestern Institute of Physics, Chengdu 610041 (China); Fu, R. K. Y. [Plasma Technology Limited, Festival Walk Tower, Tat Chee Avenue, Kowloon, Hong Kong (China); Chu, Paul K. [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China)

    2013-05-28

    Breathing oscillations in the discharge of an enlarged cylindrical-anode-layer Hall plasma accelerator are investigated by three-dimensional particle-in-cell (PIC) simulation. Different from the traditional breathing mode in a circular Hall plasma accelerator, the bulk plasma oscillation here is trigged by the potential barrier generated by the concentrated ion beam and substantial enough to compete with the anode voltage. The electric field near the anode is suppressed by the potential barrier thereby decreasing the electron density by {approx}36%. The discharge is restored to the normal level after the concentrated beam explodes and then it completes one cycle of electro-driven breathing oscillation. The breathing mode identified by the PIC simulation has a frequency range of {approx}156 kHz-{approx}250 kHz and does not vary monotonically with the discharge voltage.

  4. Terahertz emission of Bloch oscillators excited by electromagnetic field in lateral semiconductor superlattices

    International Nuclear Information System (INIS)

    Dodin, E.P.; Zharov, A.A.

    2003-01-01

    The effect of the strong high-frequency electromagnetic field on the lateral semiconductor superlattice is considered on the basis of the quasi-classical theory on the electron transport in the self-consistent wave arrangement. It is theoretically identified, that the lateral superlattice in the strong feed-up wave field may emit the terahertz radiation wave trains, which are associated with the periodical excitation of the Bloch oscillations in the superlattice. The conditions, required for the Bloch oscillators radiation observation, are determined. The spectral composition of the radiation, passing through the superlattice, and energy efficiency of multiplying the frequency, related to the Bloch oscillator excitation, are calculated [ru

  5. Multimode dynamics in a network with resource mediated coupling

    DEFF Research Database (Denmark)

    Postnov, D.E.; Sosnovtseva, Olga; Scherbakov, P.

    2008-01-01

    state of the individual unit. With this coupling, a spatially inhomogenous state with mixed high and lowamplitude oscillations in the individual units can arise. To examine generic phenomena associated with this type of interaction we consider a chain of resistively coupled electronic oscillators...... connected to a common power supply. The two- oscillator system displays antiphase synchronization, and it is interesting to note that two- mode oscillations continue to exist outside of the parameter range in which oscillations occur for the individual unit. At low coupling strengths, the multioscillator...... system shows high dimensional quasiperiodicity with little tendency for synchronization. At higher coupling strengths, one typically observes spatial clustering involving a few oscillating units. We describe three different scenarios according to which the cluster can slide along the chain as the bias...

  6. Oscillations of void lattices

    International Nuclear Information System (INIS)

    Akhiezer, A.I.; Davydov, L.N.; Spol'nik, Z.A.

    1976-01-01

    Oscillations of a nonideal crystal are studied, in which macroscopic defects (pores) form a hyperlattice. It is shown that alongside with acoustic and optical phonons (relative to the hyperlattice), in such a crystal oscillations of the third type are possible which are a hydridization of sound oscillations of atoms and surface oscillations of a pore. Oscillation spectra of all three types were obtained

  7. Nonlinear Analysis of Ring Oscillator and Cross-Coupled Oscillator Circuits

    KAUST Repository

    Ge, Xiaoqing

    2010-12-01

    Hassan Khalil’s research results and beautifully written textbook on nonlinear systems have influenced generations of researchers, including the authors of this paper. Using nonlinear systems techniques, this paper analyzes ring oscillator and cross-coupled oscillator circuits, which are essential building blocks in digital systems. The paper first investigates local and global stability properties of an n-stage ring oscillator by making use of its cyclic structure. It next studies global stability properties of a class of cross-coupled oscillators which admit the representation of a dynamic system in feedback with a static nonlinearity, and presents su cient conditions for almost global convergence of the solutions to a limit cycle when the feedback gain is in the vicinity of a bifurcation point. The result are also extended to the synchronization of interconnected identical oscillator circuits.

  8. Nonlinear Analysis of Ring Oscillator and Cross-Coupled Oscillator Circuits

    KAUST Repository

    Ge, Xiaoqing; Arcak, Murat; Salama, Khaled N.

    2010-01-01

    Hassan Khalil’s research results and beautifully written textbook on nonlinear systems have influenced generations of researchers, including the authors of this paper. Using nonlinear systems techniques, this paper analyzes ring oscillator and cross-coupled oscillator circuits, which are essential building blocks in digital systems. The paper first investigates local and global stability properties of an n-stage ring oscillator by making use of its cyclic structure. It next studies global stability properties of a class of cross-coupled oscillators which admit the representation of a dynamic system in feedback with a static nonlinearity, and presents su cient conditions for almost global convergence of the solutions to a limit cycle when the feedback gain is in the vicinity of a bifurcation point. The result are also extended to the synchronization of interconnected identical oscillator circuits.

  9. Beta Beams for Precision Measurements of Neutrino Oscillation Parameters

    CERN Document Server

    Wildner, E; Hansen, C; De Melo Mendonca, T; Stora, T; Damjanovic, S; Payet, J; Chancé, A; Zorin, V; Izotov, I; Rasin, S; Sidorov, A; Skalyga, V; De Angelis, G; Prete, G; Cinausero, M; Kravchuk, V; Gramegna, F; Marchi, T; Collazuol, G; Mezzetto, M; Delbar, T; Loiselet, M; Keutgen, T; Mitrofanov, S; Burt, G; Dexter, A; Lamy, T; Latrasse, L; Marie-Jeanne, M; Sortais, P; Thuillier, T; Debray, F; Trophime, C; Hass, M; Hirsh, T; Berkovits, D; Stahl, A; Vardaci, E; Di Nitto, A; Brondi, A; La Rana, G; Moro, R; De Rosa, G; Palladino, V

    2012-01-01

    Neutrino oscillations have implications for the Standard Model of particle physics. The CERN Beta Beam has outstanding capabilities to contribute to precision measurements of the parameters governing neutrino oscillations. The FP7 collaboration EUROnu (2008-2012) is a design study that will review three facilities (Super-Beams, Beta Beams and Neutrino Factories) and perform a cost assessment that, coupled with the physics performance, will give means to the European research authorities to make decisions on future European neutrino oscillation facilities. ”Beta Beams” produce collimated pure electron (anti)neutrinos by accelerating beta active ions to high energies and having them decay in a storage ring. Using existing machines and infrastructure is an advantage for the cost evaluation; however, this choice is also constraining the Beta Beams. Recent work to make the Beta Beam facility a solid option will be described: production of Beta Beam isotopes, the 60 GHz pulsed ECR source development, integratio...

  10. Identifying and evaluating electronic learning resources for use in adult-gerontology nurse practitioner education.

    Science.gov (United States)

    Thompson, Hilaire J; Belza, Basia; Baker, Margaret; Christianson, Phyllis; Doorenbos, Ardith; Nguyen, Huong

    2014-01-01

    Enhancing existing curricula to meet newly published adult-gerontology advanced practice registered nurse (APRN) competencies in an efficient manner presents a challenge to nurse educators. Incorporating shared, published electronic learning resources (ELRs) in existing or new courses may be appropriate in order to assist students in achieving competencies. The purposes of this project were to (a) identify relevant available ELR for use in enhancing geriatric APRN education and (b) to evaluate the educational utility of identified ELRs based on established criteria. A multilevel search strategy was used. Two independent team members reviewed identified ELR against established criteria to ensure utility. Only resources meeting all criteria were retained. Resources were found for each of the competency areas and included formats such as podcasts, Web casts, case studies, and teaching videos. In many cases, resources were identified using supplemental strategies and not through traditional search or search of existing geriatric repositories. Resources identified have been useful to advanced practice educators in improving lecture and seminar content in a particular topic area and providing students and preceptors with additional self-learning resources. Addressing sustainability within geriatric APRN education is critical for sharing of best practices among educators and for sustainability of teaching and related resources. © 2014.

  11. Systematic review of electronic surveillance of infectious diseases with emphasis on antimicrobial resistance surveillance in resource-limited settings.

    Science.gov (United States)

    Rattanaumpawan, Pinyo; Boonyasiri, Adhiratha; Vong, Sirenda; Thamlikitkul, Visanu

    2018-02-01

    Electronic surveillance of infectious diseases involves rapidly collecting, collating, and analyzing vast amounts of data from interrelated multiple databases. Although many developed countries have invested in electronic surveillance for infectious diseases, the system still presents a challenge for resource-limited health care settings. We conducted a systematic review by performing a comprehensive literature search on MEDLINE (January 2000-December 2015) to identify studies relevant to electronic surveillance of infectious diseases. Study characteristics and results were extracted and systematically reviewed by 3 infectious disease physicians. A total of 110 studies were included. Most surveillance systems were developed and implemented in high-income countries; less than one-quarter were conducted in low-or middle-income countries. Information technologies can be used to facilitate the process of obtaining laboratory, clinical, and pharmacologic data for the surveillance of infectious diseases, including antimicrobial resistance (AMR) infections. These novel systems require greater resources; however, we found that using electronic surveillance systems could result in shorter times to detect targeted infectious diseases and improvement of data collection. This study highlights a lack of resources in areas where an effective, rapid surveillance system is most needed. The availability of information technology for the electronic surveillance of infectious diseases, including AMR infections, will facilitate the prevention and containment of such emerging infectious diseases. Copyright © 2018 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved.

  12. Oscillations of disks

    CERN Document Server

    Kato, Shoji

    2016-01-01

    This book presents the current state of research on disk oscillation theory, focusing on relativistic disks and tidally deformed disks. Since the launch of the Rossi X-ray Timing Explorer (RXTE) in 1996, many high-frequency quasiperiodic oscillations (HFQPOs) have been observed in X-ray binaries. Subsequently, similar quasi-periodic oscillations have been found in such relativistic objects as microquasars, ultra-luminous X-ray sources, and galactic nuclei. One of the most promising explanations of their origin is based on oscillations in relativistic disks, and a new field called discoseismology is currently developing. After reviewing observational aspects, the book presents the basic characteristics of disk oscillations, especially focusing on those in relativistic disks. Relativistic disks are essentially different from Newtonian disks in terms of several basic characteristics of their disk oscillations, including the radial distributions of epicyclic frequencies. In order to understand the basic processes...

  13. Trapped Ion Oscillation Frequencies as Sensors for Spectroscopy

    Directory of Open Access Journals (Sweden)

    Wilfried Nörtershäuser

    2010-03-01

    Full Text Available The oscillation frequencies of charged particles in a Penning trap can serve as sensors for spectroscopy when additional field components are introduced to the magnetic and electric fields used for confinement. The presence of so-called “magnetic bottles” and specific electric anharmonicities creates calculable energy-dependences of the oscillation frequencies in the radiofrequency domain which may be used to detect the absorption or emission of photons both in the microwave and optical frequency domains. The precise electronic measurement of these oscillation frequencies therefore represents an optical sensor for spectroscopy. We discuss possible applications for precision laser and microwave spectroscopy and their role in the determination of magnetic moments and excited state lifetimes. Also, the trap-assisted measurement of radiative nuclear de-excitations in the X-ray domain is discussed. This way, the different applications range over more than 12 orders of magnitude in the detectable photon energies, from below μeV in the microwave domain to beyond MeV in the X-ray domain.

  14. Self-oscillation in spin torque oscillator stabilized by field-like torque

    International Nuclear Information System (INIS)

    Taniguchi, Tomohiro; Tsunegi, Sumito; Kubota, Hitoshi; Imamura, Hiroshi

    2014-01-01

    The effect of the field-like torque on the self-oscillation of the magnetization in spin torque oscillator with a perpendicularly magnetized free layer was studied theoretically. A stable self-oscillation at zero field is excited for negative β while the magnetization dynamics stops for β = 0 or β > 0, where β is the ratio between the spin torque and the field-like torque. The reason why only the negative β induces the self-oscillation was explained from the view point of the energy balance between the spin torque and the damping. The oscillation power and frequency for various β were also studied by numerical simulation

  15. Surface plasmon quantum cascade lasers as terahertz local oscillators

    NARCIS (Netherlands)

    Hajenius, M.; Khosropanah, P.; Hovenier, J. N.; Gao, J. R.; Klapwijk, T. M.; Barbieri, S.; Dhillon, S.; Filloux, P.; Sirtori, C.; Ritchie, D. A.; Beere, H. E.

    2008-01-01

    We characterize a heterodyne receiver based on a surface-plasmon waveguide quantum cascade laser (QCL) emitting at 2.84 THz as a local oscillator, and an NbN hot electron bolometer as a mixer. We find that the envelope of the far-field pattern of the QCL is diffraction-limited and superimposed onto

  16. A review of oscillating water columns.

    Science.gov (United States)

    Heath, T V

    2012-01-28

    This paper considers the history of oscillating water column (OWC) systems from whistling buoys to grid-connected power generation systems. The power conversion from the wave resource through to electricity via pneumatic and shaft power is discussed in general terms and with specific reference to Voith Hydro Wavegen's land installed marine energy transformer (LIMPET) plant on the Scottish island of Islay and OWC breakwater systems. A report on the progress of other OWC systems and power take-off units under commercial development is given, and the particular challenges faced by OWC developers reviewed.

  17. Design of an electronically tunable millimeter wave Gyrotron Backward Wave Oscillator

    International Nuclear Information System (INIS)

    Caplan, M.

    1987-01-01

    A non-linear self-consistent computer simulation code is used to analyze the saturated output of the Gyrotron Backward Wave Oscillator (Gyro BWO) which can be used as a tunable driver for a 250 GHz FEL amplifier. Simulations show that the Gyrotron BWO using a Pierce/Wiggler gun configuration can produce at least 10 kW of microwave power over the range 249 GHz to 265 GHz by varying beam voltage alone

  18. Magnetic-breakdown oscillations of the thermoelectric field in layered conductors

    Energy Technology Data Exchange (ETDEWEB)

    Peschanskii, V. G., E-mail: vpeschansky@ilt.kharkov.ua [Karazin Kharkov National University (Ukraine); Galbova, O. [St. Cyril and Methodium University (Macedonia, The Former Yugoslav Republic of); Hasan, R. [Karazin Kharkov National University (Ukraine)

    2016-12-15

    The response of an electron system to nonuniform heating of layered conductors with an arbitrary quasi-two-dimensional electron energy spectrum in a strong magnetic field B is investigated theoretically in the case when cyclotron frequency ω{sub c} is much higher than the frequency 1/τ of collisions between charge carriers. In the case of a multisheet Fermi surface (FS), we calculate the dependence of the thermoelectric coefficients on the magnitude and orientation of the magnetic field in the vicinity of the Lifshitz topological transition when the FS connectivity changes under the action of an external force (e.g., pressure) on the conductor. Upon a decrease in the spacing between individual pockets (sheets) of the FS, conduction electrons can tunnel as a result of the magnetic breakdown from one FS sheet to another; their motion over magneticbreakdown trajectories becomes complicated and entangled. The thermoelectric field exhibits a peculiar dependence on the magnetic field: for a noticeable deviation of vector B from the normal through angle ϑ to the layers, the thermoelectric field oscillates as a function of tanϑ. The period of these oscillations contains important information on the distance between individual FS sheets and their corrugation.

  19. Constraints on decay plus oscillation solutions of the solar neutrino problem

    Science.gov (United States)

    Joshipura, Anjan S.; Massó, Eduard; Mohanty, Subhendra

    2002-12-01

    We examine the constraints on the nonradiative decay of neutrinos from the observations of solar neutrino experiments. The standard oscillation hypothesis among three neutrinos solves the solar and atmospheric neutrino problems. The decay of a massive neutrino mixed with the electron neutrino results in the depletion of the solar neutrino flux. We introduce neutrino decay in the oscillation hypothesis and demand that decay does not spoil the successful explanation of solar and atmospheric observations. We obtain a lower bound on the ratio of the lifetime over the mass of ν2, τ2/m2>22.7 s/MeV for the Mikheyev-Smirnov-Wolfenstein solution of the solar neutrino problem and τ2/m2>27.8 s/MeV for the vacuum oscillation solution (at 99% C.L.).

  20. From Millennium ERM to Proquest 360 Resource Manager: Implementing a new Electronic Resources Management System ERMS in an International Graduate Research University in Saudi Arabia

    KAUST Repository

    Ramli, Rindra M.

    2017-01-01

    An overview of the Recommendation Study and the subsequent Implementation of a new Electronic Resources Management system ERMS in an international graduate research university in the Kingdom of Saudi Arabia. It covers the timeline, deliverables

  1. Pulsed hydrogen fluoride laser oscillator-amplifier experiments

    International Nuclear Information System (INIS)

    Schott, G.L.

    1975-01-01

    Pulsed HF chemical laser oscillator energies were scaled from millijoules to several kilojoules over the period 1970-1974, reaching approximately 10 J with SF 6 and transverse discharges, and using electron-beam initiation and elemental F 2 above 1000J. This demonstrated scalability to large energy with acceptable electrical efficiency is only one prerequisite for application of this gas laser in fusion; equally important matters are achievement of focusable, approximately 1 ns pulses, couplable to light-element targets, all from an affordable system. Exploratory MOPA experiments are reported which address control of HF laser beam focusability and pulse duration, using SF 6 -based experimental oscillator--amplifier sequences and Pockels' cell switching. Simultaneous multiline lasing with 2.6 less than or equal to lambda less than or equal to 3.1 μm and high specific gain and energy density are particularly important factors encountered with HF, where amplifier pumping and lasing occur in a substantially cw temporal relationship, even in less than 100 ns bursts. Time-resolved SF 6 --HI oscillator spectra contain 27 simultaneous lines from six vibrational bands. An apertured, SF 6 -hydrocarbon pin-discharge oscillator generates approximately 10 mJ of TEM 00 radiation, which is amplified to approximately 1 J in approximately 150 ns by a TEA amplifier and p []opagated tens of meters. A three-stage system coupling these elements through an approximately 1 ns electrooptic gate to a greater than 10 J, e-beam energized amplifier is under development. (auth)

  2. What works in auditory working memory? A neural oscillations perspective.

    Science.gov (United States)

    Wilsch, Anna; Obleser, Jonas

    2016-06-01

    Working memory is a limited resource: brains can only maintain small amounts of sensory input (memory load) over a brief period of time (memory decay). The dynamics of slow neural oscillations as recorded using magneto- and electroencephalography (M/EEG) provide a window into the neural mechanics of these limitations. Especially oscillations in the alpha range (8-13Hz) are a sensitive marker for memory load. Moreover, according to current models, the resultant working memory load is determined by the relative noise in the neural representation of maintained information. The auditory domain allows memory researchers to apply and test the concept of noise quite literally: Employing degraded stimulus acoustics increases memory load and, at the same time, allows assessing the cognitive resources required to process speech in noise in an ecologically valid and clinically relevant way. The present review first summarizes recent findings on neural oscillations, especially alpha power, and how they reflect memory load and memory decay in auditory working memory. The focus is specifically on memory load resulting from acoustic degradation. These findings are then contrasted with contextual factors that benefit neural as well as behavioral markers of memory performance, by reducing representational noise. We end on discussing the functional role of alpha power in auditory working memory and suggest extensions of the current methodological toolkit. This article is part of a Special Issue entitled SI: Auditory working memory. Published by Elsevier B.V.

  3. Observation of vacuum-enhanced electron spin resonance of optically levitated nanodiamonds

    Science.gov (United States)

    Li, Tongcang; Hoang, Thai; Ahn, Jonghoon; Bang, Jaehoon

    Electron spins of diamond nitrogen-vacancy (NV) centers are important quantum resources for nanoscale sensing and quantum information. Combining such NV spin systems with levitated optomechanical resonators will provide a hybrid quantum system for many novel applications. Here we optically levitate a nanodiamond and demonstrate electron spin control of its built-in NV centers in low vacuum. We observe that the strength of electron spin resonance (ESR) is enhanced when the air pressure is reduced. To better understand this novel system, we also investigate the effects of trap power and measure the absolute internal temperature of levitated nanodiamonds with ESR after calibration of the strain effect. Our results show that optical levitation of nanodiamonds in vacuum not only can improve the mechanical quality of its oscillation, but also enhance the ESR contrast, which pave the way towards a novel levitated spin-optomechanical system for studying macroscopic quantum mechanics. The results also indicate potential applications of NV centers in gas sensing.

  4. Light emission by an oscillator moving through a refracting plate

    International Nuclear Information System (INIS)

    Baryshevskij, V.G.

    1982-01-01

    Optical-frequency light emitted by a fast electron passing through a crystalline plate of a finite thickness is treated. Formulas are presented for the spectral distribution and intensity of the emission at a given frequency and amplitude of the electron oscillations. The formulas correspond to both normal and abnormal Doppler effects. The calculations are carried out for the light observed in the vacuum, with the reflection and refraction at the edges of the plate taken into account

  5. High-frequency plasma oscillations

    Energy Technology Data Exchange (ETDEWEB)

    Akhiezer, A I; Fainberg, Y B; Sitenko, A G; Stepanov, K; Kurilko, V; Gorbatenko, M; Kirochkin, U [Academy of Sciences of the Ukrainian SSR (USSR)

    1958-07-01

    It is well known that the electrical conductivity of a plasma, the ion-electron equilibration time, and the time required to heat the electron component of the plasma all increase greatly with increasing temperature. Consequently, the usual method of Joule heating a plasma may be difficult to apply in the region of high temperatures (> 10{sup 6}K), especially if the plasma current alone, without any additional measures, is used to generate magnetic fields for the confinement of the plasma. Therefore, it is of interest to study methods of plasma heating that do not directly use Joule heat, especially methods by which energy is directly supplied to the ion component during the time between collisions. Some of these methods make use of ionic resonance as well as other resonance phenomena which can occur in plasma in an external magnetic field. This paper deals with certain aspects of the theory of high-frequency plasma oscillations.

  6. Feasibility study of applying reactor oscillator phase method at the RB reactor; Razmatranje mogucnosti primene fazne metode reaktorskog oscilatora na reaktoru RB

    Energy Technology Data Exchange (ETDEWEB)

    Petrovic, M; Kocic, A; Markovic, V [Institute of Nuclear Sciences Boris Kidric, Vinca, Beograd (Yugoslavia)

    1965-11-15

    This paper decsribes the principles of amplitude and phase methods for applying reactor oscillator; experimental procedure and choice of optimum parameters for usractor oscillator at the RB reactor, dependent on the values of absorption properties of moderator and construction materials. Short description of the oscillator and the electronic equipment is included.

  7. The role of stochasticity in sawtooth oscillation

    International Nuclear Information System (INIS)

    Lichtenberg, A.J.; Itoh, Kimitaka; Itoh, Sanae; Fukuyama, Atsushi.

    1991-08-01

    In this paper we have demonstrated that stochastization of field lines, resulting from the interaction of the fundamental m/n=1/1 helical mode with other periodicities, plays an important role in sawtooth oscillations. The time scale for the stochastic temperature diffusion has been determined. It was shown to be sufficiently fast to account for the fast sawtooth crash, and is generally shorter than the time scales for the redistribution of current. The enhancement of the electron and ion viscosity, arising from the stochastic field lines, has been calculated. The enhanced electron viscosity always leads to an initial increase in the growth rate of the mode; the enhanced ion viscosity can ultimately lead to mode stabilization before a complete temperature redistribution or flux reconnection has occurred. A dynamical model has been introduced to calculate the path of the sawtooth oscillation through a parameter space of shear and amplitude of the helical perturbation. The stochastic trigger to the enhanced growth rate and the stabilization by the ion viscosity are also included in the mode. A reasonable prescription for the flux reconnection at the end of the growth phase allows us to determine the initial q-value for the successive sawtooth ramps. (J.P.N.)

  8. Experimental study of the stability of a neutralized electron beam

    International Nuclear Information System (INIS)

    Kudelainen, V.I.; Parkhomchuk, V.V.; Pestrikov, D.V.

    1983-01-01

    Results are reported from measurements of the spectral properties of a long neutralized electron beam in the NAP-M proton storage ring. It is shown that when the number of secondary electrons is small, both the longitudinal and the transverse oscillations are strongly damped, so that beam instability is suppressed. The current density of the neutralized electron beam produced in the experiments was approx.10 2 times greater than the theoretical value determined from the instability threshold for nonaxisymmetric oscillations

  9. High-power electronics

    CERN Document Server

    Kapitsa, Petr Leonidovich

    1966-01-01

    High-Power Electronics, Volume 2 presents the electronic processes in devices of the magnetron type and electromagnetic oscillations in different systems. This book explores the problems of electronic energetics.Organized into 11 chapters, this volume begins with an overview of the motion of electrons in a flat model of the magnetron, taking into account the in-phase wave and the reverse wave. This text then examines the processes of transmission of electromagnetic waves of various polarization and the wave reflection from grids made of periodically distributed infinite metal conductors. Other

  10. High-brightness electron injectors

    International Nuclear Information System (INIS)

    Sheffield, R.L.

    1987-01-01

    Free-electron laser (FEL) oscillators and synchrotron light sources require pulse trains of high peak brightness and, in some applications, high-average power. Recent developments in the technology of photoemissive and thermionic electron sources in rf cavities for electron-linac injector applications offer promising advances over conventional electron injectors. Reduced emittance growth in high peak-current electron injectors may be achieved by using high field strengths and by linearizing the radial component of the cavity electric field at the expense of lower shunt impedance

  11. RF Spectrum Sensing Based on an Overdamped Nonlinear Oscillator Ring for Cognitive Radios

    Directory of Open Access Journals (Sweden)

    Zhi-Ling Tang

    2016-06-01

    Full Text Available Existing spectrum-sensing techniques for cognitive radios require an analog-to-digital converter (ADC to work at high dynamic range and a high sampling rate, resulting in high cost. Therefore, in this paper, a spectrum-sensing method based on a unidirectionally coupled, overdamped nonlinear oscillator ring is proposed. First, the numerical model of such a system is established based on the circuit of the nonlinear oscillator. Through numerical analysis of the model, the critical condition of the system’s starting oscillation is determined, and the simulation results of the system’s response to Gaussian white noise and periodic signal are presented. The results show that once the radio signal is input into the system, it starts oscillating when in the critical region, and the oscillating frequency of each element is fo/N, where fo is the frequency of the radio signal and N is the number of elements in the ring. The oscillation indicates that the spectrum resources at fo are occupied. At the same time, the sampling rate required for an ADC is reduced to the original value, 1/N. A prototypical circuit to verify the functionality of the system is designed, and the sensing bandwidth of the system is measured.

  12. GLOBAL SAUSAGE OSCILLATION OF SOLAR FLARE LOOPS DETECTED BY THE INTERFACE REGION IMAGING SPECTROGRAPH

    International Nuclear Information System (INIS)

    Tian, Hui; He, Jiansen; Young, Peter R.; Reeves, Katharine K.; Wang, Tongjiang; Antolin, Patrick; Chen, Bin

    2016-01-01

    An observation from the Interface Region Imaging Spectrograph reveals coherent oscillations in the loops of an M1.6 flare on 2015 March 12. Both the intensity and Doppler shift of Fe xxi 1354.08 Å show clear oscillations with a period of ∼25 s. Remarkably similar oscillations were also detected in the soft X-ray flux recorded by the Geostationary Operational Environmental Satellites ( GOES ). With an estimated phase speed of ∼2420 km s −1 and a derived electron density of at least 5.4 × 10 10 cm −3 , the observed short-period oscillation is most likely the global fast sausage mode of a hot flare loop. We find a phase shift of ∼ π /2 (1/4 period) between the Doppler shift oscillation and the intensity/ GOES oscillations, which is consistent with a recent forward modeling study of the sausage mode. The observed oscillation requires a density contrast between the flare loop and coronal background of a factor ≥42. The estimated phase speed of the global mode provides a lower limit of the Alfvén speed outside the flare loop. We also find an increase of the oscillation period, which might be caused by the separation of the loop footpoints with time.

  13. Open-Source Electronic Health Record Systems for Low-Resource Settings: Systematic Review.

    Science.gov (United States)

    Syzdykova, Assel; Malta, André; Zolfo, Maria; Diro, Ermias; Oliveira, José Luis

    2017-11-13

    Despite the great impact of information and communication technologies on clinical practice and on the quality of health services, this trend has been almost exclusive to developed countries, whereas countries with poor resources suffer from many economic and social issues that have hindered the real benefits of electronic health (eHealth) tools. As a component of eHealth systems, electronic health records (EHRs) play a fundamental role in patient management and effective medical care services. Thus, the adoption of EHRs in regions with a lack of infrastructure, untrained staff, and ill-equipped health care providers is an important task. However, the main barrier to adopting EHR software in low- and middle-income countries is the cost of its purchase and maintenance, which highlights the open-source approach as a good solution for these underserved areas. The aim of this study was to conduct a systematic review of open-source EHR systems based on the requirements and limitations of low-resource settings. First, we reviewed existing literature on the comparison of available open-source solutions. In close collaboration with the University of Gondar Hospital, Ethiopia, we identified common limitations in poor resource environments and also the main requirements that EHRs should support. Then, we extensively evaluated the current open-source EHR solutions, discussing their strengths and weaknesses, and their appropriateness to fulfill a predefined set of features relevant for low-resource settings. The evaluation methodology allowed assessment of several key aspects of available solutions that are as follows: (1) integrated applications, (2) configurable reports, (3) custom reports, (4) custom forms, (5) interoperability, (6) coding systems, (7) authentication methods, (8) patient portal, (9) access control model, (10) cryptographic features, (11) flexible data model, (12) offline support, (13) native client, (14) Web client,(15) other clients, (16) code

  14. Demonstration of a Submillimeter-Wave HEMT Oscillator Module at 330 GHz

    Science.gov (United States)

    Radisic, Vesna; Deal, W. R.; Mei, X. B.; Yoshida, Wayne; Liu, P. H.; Uyeda, Jansen; Lai, Richard; Samoska, Lorene; Fung, King Man; Gaier, Todd; hide

    2010-01-01

    In this work, radial transitions have been successfully mated with a HEMT-based MMIC (high-electron-mobility-transistor-based monolithic microwave integrated circuit) oscillator circuit. The chip has been assembled into a WR2.2 waveguide module for the basic implementation with radial E-plane probe transitions to convert the waveguide mode to the MMIC coplanar waveguide mode. The E-plane transitions have been directly integrated onto the InP substrate to couple the submillimeter-wave energy directly to the waveguides, thus avoiding wire-bonds in the RF path. The oscillator demonstrates a measured 1.7 percent DC-RF efficiency at the module level. The oscillator chip uses 35-nm-gate-length HEMT devices, which enable the high frequency of oscillation, creating the first demonstration of a packaged waveguide oscillator that operates over 300 GHz and is based on InP HEMT technology. The oscillator chip is extremely compact, with dimensions of only 1.085 x 320 sq mm for a total die size of 0.35 sq mm. This fully integrated, waveguide oscillator module, with an output power of 0.27 mW at 330 GHz, can provide low-mass, low DC-power-consumption alternatives to existing local oscillator schemes, which require high DC power consumption and large mass. This oscillator module can be easily integrated with mixers, multipliers, and amplifiers for building high-frequency transmit and receive systems at submillimeter wave frequencies. Because it requires only a DC bias to enable submillimeter wave output power, it is a simple and reliable technique for generating power at these frequencies. Future work will be directed to further improving the applicability of HEMT transistors to submillimeter wave and terahertz applications. Commercial applications include submillimeter-wave imaging systems for hidden weapons detection, airport security, homeland security, and portable low-mass, low-power imaging systems

  15. Nanoporous metal film: An energy-dependent transmission device for electron waves

    International Nuclear Information System (INIS)

    Grech, S.; Degiovanni, A.; Lapena, L.; Morin, R.

    2011-01-01

    We measure electron transmission through free-standing ultrathin nanoporous gold films, using the coherent electron beam emitted by sharp field emission tips in a low energy electron projection microscope setup. Transmission coefficient versus electron wavelength plots show periodic oscillations between 75 and 850 eV. These oscillations result from the energy dependence of interference between paths through the gold and paths through the nanometer-sized pores of the film. We reveal that these films constitute high transmittance quantum devices acting on electron waves through a wavelength-dependent complex transmittance defined by the porosity and the thickness of the film.

  16. Electron characterization in OPERA Experiment; Caracterisation des electrons dans l'experience OPERA

    Energy Technology Data Exchange (ETDEWEB)

    Caffari, Yvan [Institut de Physique Nucleaire de Lyon, 4, Rue Enrico Fermi, 69622 Villeurbanne Cedex (France); Universite Claude Bernard Lyon-I, 43 boulevard du 11 Novembre 1918, 69622 Villeurbanne cedex (France)

    2006-09-15

    In 1998 by making use of a water Cherenkov detector the Super-Kamiokande Experiment in Japan has measured a deficit of {nu}{sub {tau}} atmospheric neutrinos without observing a corresponding rise in the {nu}{sub e} flux. This phenomenon is understood as neutrino oscillations, a mechanism implying a non vanishing neutrino mass. In 1999 the CHOOZ Experiment has definitely excluded the oscillations {nu}{sub {mu}} {yields} {nu}{sub e} within atmosphere. The OPERA Experiment aims at evidencing the {nu}{sub {mu}} {yields} {nu}{sub {tau}}oscillations through occurrence of {nu}{sub {tau}} and of {nu}{sub {mu}} {yields} {nu}{sub e} oscillations by occurrence of {nu}{sub e} starting from a muon neutrino beam almost totally clean. Such a beam is actually produced at CERN (CNGS beam) in Switzerland and then directed upon the OPERA detector located 732 km southward under Gran Sasso mountains in Italy. The detector consists of more than 200,000 bricks (what amounts to a total mass of 1,800 tons made up of a nuclear emulsion foils / lead foils sandwich. This module structure allows reconstructing with a high spatial resolution ({delta}{sub {theta}} {approx_equal} 1 mrad and {delta}{sub r} {approx_equal} 1 {mu}m) the kink topology created by the {tau} lepton (issued from charged current interaction of a {nu}{sub {tau}} lepton with a lead nucleus) and its decay products. The work reported in this thesis consists in characterization of the electrons needed in the study of {nu}{sub {mu}} {yields} {nu}{sub {tau}}oscillations, with {tau} {yields} e, and the {nu}{sub {mu}} {yields} {nu}{sub e} oscillations, the {nu}{sub e} interacting through charged currents with a lead nucleus and producing an electron. A reconstruction algorithm of the electromagnetic cascades in nuclear emulsion was developed. This algorithm allows reproducing the longitudinal and transverse profiles used in evaluating the electron energies and their identification as well ({pi}/e separation by mean of a neuron

  17. Electronic properties of asymmetrical quantum dots dressed by laser field

    Energy Technology Data Exchange (ETDEWEB)

    Kibis, O.V. [Department of Applied and Theoretical Physics, Novosibirsk State Technical University, Karl Marx Avenue 20, 630092 Novosibirsk (Russian Federation); Slepyan, G.Ya.; Maksimenko, S.A. [Institute for Nuclear Problems, Belarus State University, Bobruyskaya St. 11, 220050 Minsk (Belarus); Hoffmann, A. [Institut fuer Festkoerperphysik, Technische Universitaet Berlin, Hardenbergstrasse 36, 10623 Berlin (Germany)

    2012-05-15

    In the present paper, we demonstrate theoretically that the strong non-resonant interaction between asymmetrical quantum dots (QDs) and a laser field results in harmonic oscillations of their band gap. It is shown that such oscillations change the spectrum of elementary electron excitations in QDs: in the absence of the laser pumping there is only one resonant electron frequency, but QDs dressed by the laser field have a set of electron resonant frequencies. One expects that this modification of elementary electron excitations in QDs can be observable in optical experiments. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  18. Development of a 2 MW relativistic backward wave oscillator

    Indian Academy of Sciences (India)

    In this paper, a high power relativistic backward wave oscillator (BWO) experiment is reported. A 230 keV, 2 kA, 150 ns relativistic electron beam is generated using a Marx generator. The beam is then injected into a hollow rippled wall metallic cylindrical tube that forms a slow wave structure. The beam is guided using an ...

  19. Latitudinal oscillations of plasma within the Io torus

    Science.gov (United States)

    Cummings, W. D.; Dessler, A. J.; Hill, T. W.

    1980-01-01

    The equilibrium latitude and the period of oscillations about this equilibrium latitude are calculated for a plasma in a centrifugally dominated tilted dipole magnetic field representing Jupiter's inner magnetosphere. It is found that for a hot plasma the equilibrium latitude in the magnetic equator, for a cold plasma it is the centrifugal equator, and for a warm plasma it is somewhere in between. An illustrative model is adopted in which atoms are sputtered from the Jupiter-facing hemisphere of Io and escape Io's gravity to be subsequently ionized some distance from Io. Finally, it is shown that ionization generally does not occur at the equilibrium altitude, and that the resulting latitudinal oscillations provide an explanation for the irregularities in electron concentration within the torus, as reported by the radioastronomy experiment aboard Voyager I.

  20. Theoretical Investigation of Current Instabilities and Terahertz Oscillations in a Two-Dimensional Electron Fluid

    National Research Council Canada - National Science Library

    Dyakonov, M

    1997-01-01

    The purpose of this work is to develop further the theory of novel mechanisms for generation and detection of electromagnetic radiation in the terahertz range using the plasma oscillations of the two...

  1. Electrons in a Magnetic Field: Special Spin in de Haas-van Alphen effect

    International Nuclear Information System (INIS)

    Shrivastava, Keshav N

    2012-01-01

    When the magnetic field is applied in a metal, the electrons behave like a harmonic oscillator. When the field is increased these harmonic oscillator type levels cross the Fermi energy at a particular point resulting into the discontinuities in the population of any particular level at that point. For a large orbital magnetic moment, different from L = 0 and both signs of spin in the total magnetic momentum quantum number, j = l ± s, the discontinuities in the population of the electrons in a particular level become double valued resulting into doubling of oscillations in the magnetization. There is a double valued change in the energy of the electrons when they transfer from the harmonic oscillator type level to the Fermi level. The magnetization depends on the value of j = l ± s so that there is a double valued period in the oscillations. The de Haas-van Alphen effect is usually described for the L = 0 electrons. Hence, we see that the de Haas-van Alphen effect is considerably modified in going from L = 0 to j = l ± s, with both signs in the spin.

  2. Efficient Low-Voltage Operation of a CW Gyrotron Oscillator at 233 GHz.

    Science.gov (United States)

    Hornstein, Melissa K; Bajaj, Vikram S; Griffin, Robert G; Temkin, Richard J

    2007-02-01

    The gyrotron oscillator is a source of high average power millimeter-wave through terahertz radiation. In this paper, we report low beam power and high-efficiency operation of a tunable gyrotron oscillator at 233 GHz. The low-voltage operating mode provides a path to further miniaturization of the gyrotron through reduction in the size of the electron gun, power supply, collector, and cooling system, which will benefit industrial and scientific applications requiring portability. Detailed studies of low-voltage operation in the TE(2) (,) (3) (,) (1) mode reveal that the mode can be excited with less than 7 W of beam power at 3.5 kV. During CW operation with 3.5-kV beam voltage and 50-mA beam current, the gyrotron generates 12 W of RF power at 233.2 GHz. The EGUN electron optics code describes the low-voltage operation of the electron gun. Using gun-operating parameters derived from EGUN simulations, we show that a linear theory adequately predicts the low experimental starting currents.

  3. Oscillation effects on high-energy neutrino fluxes from astrophysical hidden sources

    International Nuclear Information System (INIS)

    Mena, Olga; Mocioiu, Irina; Razzaque, Soebur

    2007-01-01

    High-energy neutrinos are expected to be produced in a variety of astrophysical sources as well as in optically thick hidden sources. We explore the matter-induced oscillation effects on emitted neutrino fluxes of three different flavors from the latter class. We use the ratio of electron and tau induced showers to muon tracks, in upcoming neutrino telescopes, as the principal observable in our analysis. This ratio depends on the neutrino energy, density profile of the sources, and on the oscillation parameters. The largely unknown flux normalization drops out of our calculation and only affects the statistics. For the current knowledge of the oscillation parameters we find that the matter-induced effects are non-negligible and the enhancement of the ratio from its vacuum value takes place in an energy range where the neutrino telescopes are the most sensitive. Quantifying the effect would be useful to learn about the astrophysics of the sources as well as the oscillation parameters. If the neutrino telescopes mostly detect diffuse neutrinos without identifying their sources, then any deviation of the measured flux ratios from the vacuum expectation values would be most naturally explained by a large population of hidden sources for which matter-induced neutrino oscillation effects are important

  4. Are the North Atlantic oscillation and the southern oscillation related in any time-scale?

    Energy Technology Data Exchange (ETDEWEB)

    Garcia, R.; Ribera, P.; Hernandez, E. [Universidad Complutense de Madrid (Spain). Facultad de Ciencias Fisicas; Gimenoo, L. [Fac. Ciencias, Univ. Vigo, Ourense (Spain)

    2000-02-01

    The north Atlantic oscillation (NAO) and the southern oscillation (SO) are compared from the standpoint of a possible common temporal scale of oscillation. To do this a cross-spectrum of the temporal series of NAO and SO indices was determined, finding a significant common oscillation of 6-8 years. To assure this finding, both series were decomposed in their main oscillations using singular spectrum analysis (SSA). Resulting reconstructed series of 6-8 years' oscillation were then cross-correlated without and with pre-whitened, the latter being significant. The main conclusion is a possible relationship between a common oscillation of 6-8 years that represents about 20% of the SO variance and about 25% of the NAO variance. (orig.)

  5. Automatic Oscillating Turret.

    Science.gov (United States)

    1981-03-01

    Final Report: February 1978 ZAUTOMATIC OSCILLATING TURRET SYSTEM September 1980 * 6. PERFORMING 01G. REPORT NUMBER .J7. AUTHOR(S) S. CONTRACT OR GRANT...o....e.... *24 APPENDIX P-4 OSCILLATING BUMPER TURRET ...................... 25 A. DESCRIPTION 1. Turret Controls ...Other criteria requirements were: 1. Turret controls inside cab. 2. Automatic oscillation with fixed elevation to range from 20* below the horizontal to

  6. Inverted oscillator

    Energy Technology Data Exchange (ETDEWEB)

    Yuce, C [Physics Department, Anadolu University, Eskisehir (Turkey); Kilic, A [Physics Department, Anadolu University, Eskisehir (Turkey); Coruh, A [Physics Department, Sakarya University, Sakarya (Turkey)

    2006-07-15

    The inverted harmonic oscillator problem is investigated quantum mechanically. The exact wavefunction for the confined inverted oscillator is obtained and it is shown that the associated energy eigenvalues are discrete, and the energy is given as a linear function of the quantum number n.

  7. Reply to “Comment on ‘Axion induced oscillating electric dipole moments’”

    Energy Technology Data Exchange (ETDEWEB)

    Hill, Christopher T.

    2017-03-28

    A recent paper of Flambaum, Roberts and Stadnik, [1], claims there is no induced oscillating electric dipole moment (OEDM), eg, for the electron, arising from the oscillating cosmic axion background via the anomaly. This claim is based upon the assumption that electric dipoles always be defined by their coupling to static (constant in time) electric fields. The relevant Feynman diagram, as computed by [1], then becomes a total divergence, and vanishes in momentum space. However, an OEDM does arise from the anomaly, coupled to time dependent electric fields. It shares the decoupling properties with the anomaly. The full action, in an arbitrary gauge, was computed in [2], [3]. It is nonvanishing with a time dependent outgoing photon, and yields physics, eg, electric dipole radiation of an electron immersed in a cosmic axion field.

  8. Reactor oscillator - Proposal of the organisation for oscillator operation; Reaktorski oscilator - Predlog organizacije rada na oscilatoru

    Energy Technology Data Exchange (ETDEWEB)

    Lolic, B; Loloc, B [Institute of Nuclear Sciences Boris Kidric, Laboratorija za fiziku reaktora, Vinca, Beograd (Serbia and Montenegro)

    1961-12-15

    The organizational structure for operating the reactor with the reactor oscillator describes the duties of the reactor operators; staff responsible for operating the oscillator who are responsible for measurements, preparation of the samples and further treatment of the obtained results.

  9. Study of optical and electronic properties of nickel from reflection electron energy loss spectra

    Science.gov (United States)

    Xu, H.; Yang, L. H.; Da, B.; Tóth, J.; Tőkési, K.; Ding, Z. J.

    2017-09-01

    We use the classical Monte Carlo transport model of electrons moving near the surface and inside solids to reproduce the measured reflection electron energy-loss spectroscopy (REELS) spectra. With the combination of the classical transport model and the Markov chain Monte Carlo (MCMC) sampling of oscillator parameters the so-called reverse Monte Carlo (RMC) method was developed, and used to obtain optical constants of Ni in this work. A systematic study of the electronic and optical properties of Ni has been performed in an energy loss range of 0-200 eV from the measured REELS spectra at primary energies of 1000 eV, 2000 eV and 3000 eV. The reliability of our method was tested by comparing our results with the previous data. Moreover, the accuracy of our optical data has been confirmed by applying oscillator strength-sum rule and perfect-screening-sum rule.

  10. Nonadiabatic anharmonic electron transfer

    Energy Technology Data Exchange (ETDEWEB)

    Schmidt, P. P. [Molecular Physics Research, 6547 Kristina Ursula Court, Falls Church, Virginia 22044 (United States)

    2013-03-28

    The effect of an inner sphere, local mode vibration on an electron transfer is modeled using the nonadiabatic transition probability (rate) expression together with both the anharmonic Morse and the harmonic oscillator potential. For an anharmonic inner sphere mode, a variational analysis uses harmonic oscillator basis functions to overcome the difficulties evaluating Morse-model Franck-Condon overlap factors. Individual matrix elements are computed with the use of new, fast, robust, and flexible recurrence relations. The analysis therefore readily addresses changes in frequency and/or displacement of oscillator minimums in the different electron transfer states. Direct summation of the individual Boltzmann weighted Franck-Condon contributions avoids the limitations inherent in the use of the familiar high-temperature, Gaussian form of the rate constant. The effect of harmonic versus anharmonic inner sphere modes on the electron transfer is readily seen, especially in the exoergic, inverted region. The behavior of the transition probability can also be displayed as a surface for all temperatures and values of the driving force/exoergicity {Delta}=-{Delta}G. The temperature insensitivity of the transfer rate is clearly seen when the exoergicity equals the collective reorganization energy ({Delta}={Lambda}{sub s}) along a maximum ln (w) vs. {Delta} ridge of the surface. The surface also reveals additional regions for {Delta} where ln (w) appears to be insensitive to temperature, or effectively activationless, for some kinds of inner sphere contributions.

  11. Evaluation of three electronic report processing systems for preparing hydrologic reports of the U.S Geological Survey, Water Resources Division

    Science.gov (United States)

    Stiltner, G.J.

    1990-01-01

    In 1987, the Water Resources Division of the U.S. Geological Survey undertook three pilot projects to evaluate electronic report processing systems as a means to improve the quality and timeliness of reports pertaining to water resources investigations. The three projects selected for study included the use of the following configuration of software and hardware: Ventura Publisher software on an IBM model AT personal computer, PageMaker software on a Macintosh computer, and FrameMaker software on a Sun Microsystems workstation. The following assessment criteria were to be addressed in the pilot studies: The combined use of text, tables, and graphics; analysis of time; ease of learning; compatibility with the existing minicomputer system; and technical limitations. It was considered essential that the camera-ready copy produced be in a format suitable for publication. Visual improvement alone was not a consideration. This report consolidates and summarizes the findings of the electronic report processing pilot projects. Text and table files originating on the existing minicomputer system were successfully transformed to the electronic report processing systems in American Standard Code for Information Interchange (ASCII) format. Graphics prepared using a proprietary graphics software package were transferred to all the electronic report processing software through the use of Computer Graphic Metafiles. Graphics from other sources were entered into the systems by scanning paper images. Comparative analysis of time needed to process text and tables by the electronic report processing systems and by conventional methods indicated that, although more time is invested in creating the original page composition for an electronically processed report , substantial time is saved in producing subsequent reports because the format can be stored and re-used by electronic means as a template. Because of the more compact page layouts, costs of printing the reports were 15% to 25

  12. Electron Acoustic Waves in Pure Ion Plasmas

    Science.gov (United States)

    Anderegg, F.; Driscoll, C. F.; Dubin, D. H. E.; O'Neil, T. M.

    2009-11-01

    Electron Acoustic Waves (EAW) are the low frequency branch of electrostatic plasma waves. These waves exist in neutralized plasmas, pure electron plasmas and in pure ion plasmasfootnotetextF. Anderegg et al., PRL 102, 095001 (2009) and PoP 16, 055705 (2009). (where the name is deceptive). Here, we observe standing mθ= 0 mz= 1 EAWs in a pure ion plasma column. At small amplitude, the EAWs have a phase velocity vph ˜1.4 v, and the frequencies are in close agreement with theory. At moderate amplitudes, waves can be excited over a broad range of frequencies, with observed phase velocities in the range of 1.4 v vph diagnostic shows that particles slower than vph oscillate in phase with the wave, while particles moving faster than vph oscillate 180^o out of phase with the wave. From a fluid perspective, this gives an unusual negative dynamical compressibility. That is, the wave pressure oscillations are 180^o out of phase from the density oscillations, almost fully canceling the electrostatic restoring force, giving the low and malleable frequency.

  13. Electronic circuits fundamentals & applications

    CERN Document Server

    Tooley, Mike

    2015-01-01

    Electronics explained in one volume, using both theoretical and practical applications.New chapter on Raspberry PiCompanion website contains free electronic tools to aid learning for students and a question bank for lecturersPractical investigations and questions within each chapter help reinforce learning Mike Tooley provides all the information required to get to grips with the fundamentals of electronics, detailing the underpinning knowledge necessary to appreciate the operation of a wide range of electronic circuits, including amplifiers, logic circuits, power supplies and oscillators. The

  14. Coherence limits and chirp control in long pulse free electron laser oscillator

    Directory of Open Access Journals (Sweden)

    Y. Socol

    2005-08-01

    Full Text Available We report experimental studies of the spectral linewidth and chirp characteristics of the mm-wave rf radiation of the Israeli Electrostatic-Accelerator free electron laser (EA-FEL, along with theory and numerical simulations. The simulations, matching the experimental data, were carried out using a space-frequency-domain model. EA-FELs have the capacity to generate long pulses of tens microseconds and more, that in principle can be elongated indefinitely (cw operation. Since a cold beam FEL is by nature a “homogeneously broadened laser,” EA-FEL can operate, unlike other kinds of FELs, at a single longitudinal mode (single frequency. This allows the generation of very coherent radiation. The current status of the Israeli Tandem Electrostatic-Accelerator FEL, which is based on an electrostatic Van de Graaff accelerator, allows the generation of pulses of tens microseconds duration. It has been operated recently past saturation, and produced single-mode coherent radiation of record narrow inherent relative linewidth ∼Δf/f=10^{-6} at frequencies near 100 GHz. A frequency chirp was observed during the pulses of tens of microseconds (0.3–0.5  MHz/ms. This is essentially a drifting “frequency-pulling effect,” associated with the accelerator voltage drop during the pulse. Additionally, damped relaxation of the FEL oscillator was experimentally measured at the beginning and the end of the lasing pulse, in good correspondence to our theory and numerical simulations. We propose using the chirped signal of the pulsed EA-FEL for single pulse sweep spectroscopy of very fine resolution. The characteristics of this application are analyzed based on the experimental data.

  15. Free electron laser

    International Nuclear Information System (INIS)

    Ortega, J.M.; Billardon, M.

    1986-01-01

    Operation principle of a laser and an oscillator are recalled together with the klystron one. In the free electron laser, electrons go through an undulator or an optical klystron. Principles of the last one are given. The two distinct ways of producing coherent radiation with an undulator and an optical klystron are presented. The first one is the use of the free electron laser, the second is to make use of the spontaneous emission generation (harmonics generation). The different current types of free electron lasers are presented (Stanford, Los Alamos, Aco at Orsay). Prospects and applications are given in conclusion [fr

  16. Recharge beneath low-impact design rain gardens and the influence of El Niño Southern Oscillation on urban, coastal groundwater resources

    Science.gov (United States)

    Newcomer, M. E.; Gurdak, J. J.

    2011-12-01

    Groundwater resources in urban, coastal environments are highly vulnerable to increased human pressures and climate variability. Impervious surfaces, such as buildings, roads, and parking lots prevent infiltration, reduce recharge to underlying aquifers, and increase contaminants in surface runoff that often overflow sewage systems. To mitigate these effects, cities worldwide are adopting low impact design (LID) approaches that direct runoff into natural vegetated systems, such as rain gardens that reduce, filter, and slow stormwater runoff, and are hypothesized to increase infiltration and recharge rates to aquifers. The effects of LID on recharge rates and quality is unknown, particularly during intense precipitation events for cities along the Pacific coast in response to interannual variability of the El Niño Southern Oscillation (ENSO). Using vadose zone monitoring sensors and instruments, I collected and monitored soil, hydraulic, and geochemical data to quantify the rates and quality of infiltration and recharge to the California Coastal aquifer system beneath a LID rain garden and traditional turf-lawn setting in San Francisco, CA. The data were used to calibrate a HYDRUS-3D model to simulate recharge rates under historical and future variability of ENSO. Understanding these processes has important implications for managing groundwater resources in urban, coastal environments.

  17. Investigation on multi-frequency oscillations in InGaAs planar Gunn diode with multiple anode-cathode spacings

    Science.gov (United States)

    Li, B.; Alimi, Y.; Ma, G. L.

    2016-12-01

    Current oscillations in an AlGaAs/InGaAs/AlGaAs-based two-dimensional electron gas (2DEG)-based hetero-structure have been investigated by means of semiconductor device simulation software SILVACO, with an interest on the charge domain formation at large biases. Single-frequency oscillations are generated in planar Gunn diodes with uniform anode and cathode contacts. The oscillation frequency reduces as the applied bias voltage increases. We show that it is possible to create multiple, independent charge domains in a novel Gunn diode structure with designed multiple anode-cathode spacings. This enables simultaneous generation of multiple frequency oscillations in a single planar device, in contrast to traditional vertical Gunn diodes where only single-frequency oscillations can be achieved. More interestingly, frequency mixing in multiple-channel configured Gunn diodes appeared. This proof-of-concept opens up the possibility for realizing compact self-oscillating mixer at millimeter-wave applications.

  18. Optically detected SdH oscillations in CdTe/(CdMg)Te and CdTe/(CdMnMg)Te modulation doped quantum wells

    International Nuclear Information System (INIS)

    Shen, J.X.; Ossau, W.; Fischer, F.; Waag, A.; Landwehr, G.

    1995-01-01

    Oscillations of photoluminescence properties in external magnetic fields are investigated in CdTe modulation doped quantum wells. The oscillatory behaviour of the luminescence intensity, the line width and the g factor is due to many-body effects in the 2-dimensional electron gas. The oscillation of photoluminescence intensity can be easily used as optically detected Shubnikov de Haas effect to determine the electron concentration in quantum wells without contacts. (author)

  19. Use and User Perception of Electronic Information Resources: A Case Study of Siva Institute of Frontier Technology, India

    Directory of Open Access Journals (Sweden)

    Velmurugan Chandran

    2013-12-01

    Full Text Available The present study aims to explore the use and user perception of electronic resources in Siva Institute of Frontier Technology, India. A total number of 123 users were taken into account for the study through a questionnaire-based survey method. A well-structured questionnaire was designed and distributed to the selected 200 students and staff members. 123 copies of the questionnaires were returned dully filled in and the overall response rate was 61.50 percent. The questionnaire contained both open- and close-ended questions. The collected data were classified, analyzed, and tabulated by using simple statistical methods. This study covers the impact of electronic resources on students and faculty in their academic pursuit.

  20. A preliminary categorization of end-of-life electrical and electronic equipment as secondary metal resources

    International Nuclear Information System (INIS)

    Oguchi, Masahiro; Murakami, Shinsuke; Sakanakura, Hirofumi; Kida, Akiko; Kameya, Takashi

    2011-01-01

    Highlights: → End-of-life electrical and electronic equipment (EEE) as secondary metal resources. → The content and the total amount of metals in specific equipment are both important. → We categorized 21 EEE types from contents and total amounts of various metals. → Important equipment types as secondary resources were listed for each metal kind. → Collectability and possible collection systems of various EEE types were discussed. - Abstract: End-of-life electrical and electronic equipment (EEE) has recently received attention as a secondary source of metals. This study examined characteristics of end-of-life EEE as secondary metal resources to consider efficient collection and metal recovery systems according to the specific metals and types of EEE. We constructed an analogy between natural resource development and metal recovery from end-of-life EEE and found that metal content and total annual amount of metal contained in each type of end-of-life EEE should be considered in secondary resource development, as well as the collectability of the end-of-life products. We then categorized 21 EEE types into five groups and discussed their potential as secondary metal resources. Refrigerators, washing machines, air conditioners, and CRT TVs were evaluated as the most important sources of common metals, and personal computers, mobile phones, and video games were evaluated as the most important sources of precious metals. Several types of small digital equipment were also identified as important sources of precious metals; however, mid-size information and communication technology (ICT) equipment (e.g., printers and fax machines) and audio/video equipment were shown to be more important as a source of a variety of less common metals. The physical collectability of each type of EEE was roughly characterized by unit size and number of end-of-life products generated annually. Current collection systems in Japan were examined and potentially appropriate collection

  1. Electron heating via self-excited plasma series resonance in geometrically symmetric multi-frequency capacitive plasmas

    International Nuclear Information System (INIS)

    Schüngel, E; Brandt, S; Schulze, J; Donkó, Z; Korolov, I; Derzsi, A

    2015-01-01

    The self-excitation of plasma series resonance (PSR) oscillations plays an important role in the electron heating dynamics in capacitively coupled radio-frequency (CCRF) plasmas. In a combined approach of PIC/MCC simulations and a theoretical model based on an equivalent circuit, we investigate the self-excitation of PSR oscillations and their effect on the electron heating in geometrically symmetric CCRF plasmas driven by multiple consecutive harmonics. The discharge symmetry is controlled via the electrical asymmetry effect (EAE), i.e. by varying the total number of harmonics and tuning the phase shifts between them. It is demonstrated that PSR oscillations will be self-excited under both symmetric and asymmetric conditions, if (i) the charge–voltage relation of the plasma sheaths deviates from a simple quadratic behavior and (ii) the inductance of the plasma bulk exhibits a temporal modulation. These two effects have been neglected up to now, but we show that they must be included in the model in order to properly describe the nonlinear series resonance circuit and reproduce the self-excitation of PSR oscillations, which are observed in the electron current density resulting from simulations of geometrically symmetric CCRF plasmas. Furthermore, the effect of PSR self-excitation on the discharge current and the plasma properties, such as the potential profile, is illustrated by applying Fourier analysis. High-frequency oscillations in the entire spectrum between the applied frequencies and the local electron plasma frequency are observed. As a consequence, the electron heating is strongly enhanced by the presence of PSR oscillations. A complex electron heating dynamics is found during the expansion phase of the sheath, which is fully collapsed, when the PSR is initially self-excited. The nonlinear electron resonance heating (NERH) associated with the PSR oscillations causes a spatial asymmetry in the electron heating. By discussing the resulting ionization

  2. Chromospheric oscillations

    NARCIS (Netherlands)

    Lites, B.W.; Rutten, R.J.; Thomas, J.H.

    1995-01-01

    We show results from SO/Sacramento Peak data to discuss three issues: (i)--the spatial occurrence of chromospheric 3--min oscillations; (ii)--the validity of Ca II H&K line-center Doppler Shift measurements; (iii)--the signi ?cance of oscillation power and phase at frequencies above 10 mHz.

  3. Electron transport through monovalent atomic wires

    DEFF Research Database (Denmark)

    Lee, Y. J.; Brandbyge, Mads; Puska, M. J.

    2004-01-01

    at the chain determine the conductance. As a result, the conductance for noble-metal chains is close to one quantum of conductance, and it oscillates moderately so that an even number of chain atoms yields a higher value than an odd number. The conductance oscillations are large for alkali-metal chains......Using a first-principles density-functional method we model electron transport through linear chains of monovalent atoms between two bulk electrodes. For noble-metal chains the transport resembles that for free electrons over a potential barrier whereas for alkali-metal chains resonance states...... and their phase is opposite to that of noble-metal chains....

  4. Cross sections for inelastic scattering of electrons by atoms: selected topics related to electron microscopy

    International Nuclear Information System (INIS)

    Inokuti, M.; Manson, S.T.

    1982-01-01

    We begin with a resume of the Bethe theory, which provides a general framework for discussing the inelastic scattering of fast electrons and leads to powerful criteria for judging the reliability of cross-section data. The central notion of the theory is the generalized oscillator strength as a function of both the energy transfer and the momentum transfer, and is the only non-trivial factor in the inelastic-scattering cross section. Although the Bethe theory was initially conceived for free atoms, its basic ideas apply to solids, with suitable generalizations; in this respect, the notion of the dielectric response function is the most fundamental. Topics selected for discussion include the generalized oscillator strengths for the K-shell and L-shell ionization for all atoms with Z less than or equal to 30, evaluated by use of the Hartree-Slater potential. As a function of the energy transfer, the generalized oscillator strength most often shows a non-monotonic structure near the K-shell and L-shell thresholds, which has been interpreted as manifestations of electron-wave propagation through atomic fields. For molecules and solids, there are additional structures due to the scattering of ejected electrons by the fields of other atoms

  5. Neutrino oscillations in dense neutrino gases

    International Nuclear Information System (INIS)

    Samuel, S.

    1993-01-01

    We consider oscillations of neutrinos under conditions in which the neutrino density is sufficiently large that neutrino-neutrino interactions cannot be neglected. A formalism is developed to treat this highly nonlinear system. Numerical analysis reveals a rich array of phenomena. In certain gases, a self-induced Mikheyev-Smirnov-Wolfenstein effect occurs in which electron neutrinos are resonantly converted into muon neutrinos. In another relatively low-density gas, an unexpected parametric resonant conversion takes place. Finally, neutrino-neutrino interactions maintain coherence in one system for which a priori one expected decoherence

  6. Conductance oscillations of core-shell nanowires in transversal magnetic fields

    Science.gov (United States)

    Manolescu, Andrei; Nemnes, George Alexandru; Sitek, Anna; Rosdahl, Tomas Orn; Erlingsson, Sigurdur Ingi; Gudmundsson, Vidar

    2016-05-01

    We analyze theoretically electronic transport through a core-shell nanowire in the presence of a transversal magnetic field. We calculate the conductance for a variable coupling between the nanowire and the attached leads and show how the snaking states, which are low-energy states localized along the lines of the vanishing radial component of the magnetic field, manifest their existence. In the strong-coupling regime they induce flux periodic, Aharonov-Bohm-like, conductance oscillations, which, by decreasing the coupling to the leads, evolve into well-resolved peaks. The flux periodic oscillations arise due to interference of the snaking states, which is a consequence of backscattering at either the contacts with leads or magnetic or potential barriers in the wire.

  7. Double electron transfer in H- + H+ collisions

    International Nuclear Information System (INIS)

    Braeuning, H; Helm, H; Briggs, J S; Salzborn, E

    2007-01-01

    Absolute cross sections for double electron transfer in H - + H + collisions have been measured for center-of-mass energies from 0.5 keV to 12 keV. Clear oscillations in the cross section are observed which are in excellent agreement with earlier measurements at lower energies by Brouillard et al (1979) as well as Peart and Dolder (1979). After an oscillation maximum at 3 keV center-of-mass energy the cross section decreases for increasing energy with no indication of further oscillations

  8. A ferroelectric electron gun in a free-electron maser experiment

    International Nuclear Information System (INIS)

    Einat, M.; Jerby, E.; Rosenman, G.

    2002-01-01

    An electron-gun based on a ferroelectric cathode is studied in a free-electron maser (FEM) experiment. In this gun, the electrons are separated from the cathode surface plasma, and are accelerated in two stages. The electron energy-spread is reduced sufficiently for an FEM operation in the microwave regime. A 14 keV, 1-2 A e-beam is obtained in a 0.1-2.1 μs pulse width. The pulse repetition frequency attains 3.1 MHz in ∼50% duty-cycle. This gun is implemented in an FEM oscillator experiment operating around 3 GHz. The paper presents experimental results and discusses the applicability of ferroelectric guns in free-electron laser devices

  9. A ferroelectric electron gun in a free-electron maser experiment

    CERN Document Server

    Einat, M; Rosenman, G

    2002-01-01

    An electron-gun based on a ferroelectric cathode is studied in a free-electron maser (FEM) experiment. In this gun, the electrons are separated from the cathode surface plasma, and are accelerated in two stages. The electron energy-spread is reduced sufficiently for an FEM operation in the microwave regime. A 14 keV, 1-2 A e-beam is obtained in a 0.1-2.1 mu s pulse width. The pulse repetition frequency attains 3.1 MHz in approx 50% duty-cycle. This gun is implemented in an FEM oscillator experiment operating around 3 GHz. The paper presents experimental results and discusses the applicability of ferroelectric guns in free-electron laser devices.

  10. Principles of formation of the content of an educational electronic resource on the basis of general and didactic patterns of learning

    Directory of Open Access Journals (Sweden)

    Ольга Юрьевна Заславская

    2018-12-01

    Full Text Available The article considers the influence of the development of technical means of teaching on the effectiveness of educational and methodical resources. Modern opportunities of information and communication technologies allow creating electronic educational resources that represent educational information that automates the learning process, provide information assistance, if necessary, collect and process statistical information on the degree of development of the content of the school material by schoolchildren, set an individual trajectory of learning, and so on. The main principle of data organization is the division of the training course into separate sections on the thematic elements and components of the learning process. General regularities include laws that encompass the entire didactic system, and in specific (particular cases, those whose actions extend to a separate component (aspect of the system. From the standpoint of the existence of three types of electronic training modules in the aggregate content of the electronic learning resource - information, control and module of practical classes - the principles of the formation of the electronic learning resource, in our opinion, should regulate all these components. Each of the certain principles is considered in the groups: scientific orientation, methodological orientation, systemic nature, accounting of interdisciplinary connections, fundamentalization, systematic and dosage sequence, rational use of study time, accessibility, minimization, operationalization of goals, unified identification diagnosis.

  11. Oscillation Baselining and Analysis Tool

    Energy Technology Data Exchange (ETDEWEB)

    2017-03-27

    PNNL developed a new tool for oscillation analysis and baselining. This tool has been developed under a new DOE Grid Modernization Laboratory Consortium (GMLC) Project (GM0072 - “Suite of open-source applications and models for advanced synchrophasor analysis”) and it is based on the open platform for PMU analysis. The Oscillation Baselining and Analysis Tool (OBAT) performs the oscillation analysis and identifies modes of oscillations (frequency, damping, energy, and shape). The tool also does oscillation event baselining (fining correlation between oscillations characteristics and system operating conditions).

  12. Measurements of fluctuations in the flux of runaway electrons to the PLT limiter

    International Nuclear Information System (INIS)

    Barnes, C.W.; Strachan, J.D.

    1982-07-01

    Fluctuations in the flux of runaway electrons to the limiter have been measured during many PLT discharges. Oscillations at 60, 120, and 720 Hz are driven by variations in the vertical magnetic field which moves the plasma major radius. Fluctuations are seen in the range of 2 → 20 kHz due to MHD magnetic islands which extend to the plasma surface. A continuous spectrum of fluctuations is observed up to 200 kHz which correlates with drift-wave turbulence. The magnitude of the driven fluctuations can be used to measure transport properties of the runaway electrons. The amplitude of electron motion due to the MHD and drift-wave oscillations, and hence a measure of the radial size of the instability, can be determined as a function of frequency. The slope of the frequency power spectrum of the drift-wave-induced fluctuations steepens with increasing runaway electron drift orbit displacement during the current drop at the end of the discharge, and as the power in the MHD oscillations increases. A magnetic probe was used to confirm the presence of oscillating magnetic fields capable of perturbing the electron orbits

  13. The art of linear electronics

    CERN Document Server

    Hood, John Linsley

    2013-01-01

    The Art of Linear Electronics presents the principal aspects of linear electronics and techniques in linear electronic circuit design. The book provides a wide range of information on the elucidation of the methods and techniques in the design of linear electronic circuits. The text discusses such topics as electronic component symbols and circuit drawing; passive and active semiconductor components; DC and low frequency amplifiers; and the basic effects of feedback. Subjects on frequency response modifying circuits and filters; audio amplifiers; low frequency oscillators and waveform generato

  14. Quantum oscillations in quasi-two-dimensional conductors

    CERN Document Server

    Galbova, O

    2002-01-01

    The electronic absorption of sound waves in quasi-two-dimensional conductors in strong magnetic fields, is investigated theoretically. A longitudinal acoustic wave, propagating along the normal n-> to the layer of quasi-two-dimensional conductor (k-> = left brace 0,0,k right brace; u-> = left brace 0,0,u right brace) in magnetic field (B-> = left brace 0, 0, B right brace), is considered. The quasiclassical approach for this geometry is of no interest, due to the absence of interaction between electromagnetic and acoustic waves. The problem is of interest in strong magnetic field when quantization of the charge carriers energy levels takes place. The quantum oscillations in the sound absorption coefficient, as a function of the magnetic field, are theoretically observed. The experimental study of the quantum oscillations in quasi-two-dimensional conductors makes it possible to solve the inverse problem of determining from experimental data the extrema closed sections of the Fermi surface by a plane p sub z = ...

  15. From Millennium ERM to Proquest 360 Resource Manager: Implementing a new Electronic Resources Management System ERMS in an International Graduate Research University in Saudi Arabia

    KAUST Repository

    Ramli, Rindra M.

    2017-05-17

    An overview of the Recommendation Study and the subsequent Implementation of a new Electronic Resources Management system ERMS in an international graduate research university in the Kingdom of Saudi Arabia. It covers the timeline, deliverables and challenges as well as lessons learnt by the Project Team.

  16. Matter oscillations and solar neutrinos: A review of the MSW [Mikheyev-Smirnov-Wolfenstein] effect

    International Nuclear Information System (INIS)

    Rosen, S.P.; Gelb, J.M.

    1986-01-01

    We review the theory of the Mikheyev-Smirnov-Wolfenstein effect, in which matter oscillations can greatly enhance ''in vacuo'' neutrino oscillations, and we examine its consequences for the solar neutrino problem. Using a two-flavor model, we discuss the solutions in the Δm 2 -sin 2 2Θ parameter space for the 37 Cl experiment, and describe their predictions for the 71 Ga experiment and for the spectrum of electron-neutrinos arriving at earth. We also comment on the three-flavor case

  17. Neutrino oscillations in matter

    International Nuclear Information System (INIS)

    Mikheyev, S.P.; Smirnov, A.Yu.

    1986-01-01

    In this paper we describe united formalism of ν-oscillations for different regimes, which is immediate generalization of vacuum oscillations theory. Adequate graphical representation of this formalism is given. We summarize main properties of ν-oscillations for different density distributions. (orig./BBOE)

  18. Fast-electron-impact study on excitations of 4p, 4s, and 3d electrons of krypton

    International Nuclear Information System (INIS)

    Yuan Zhensheng; Zhu Linfan; Liu Xiaojing; Li Wenbin; Cheng Huadong; Xu Kezun; Zhong Zhiping

    2002-01-01

    Absolute optical oscillator strength densities for the excitations of the electrons 4p, 4s, and 3d have been measured. Their absolute optical oscillator strengths have also been obtained. An enhancement above the 4p ionization threshold in the photoabsorption spectrum was assigned as a delayed maximum which arises from the photoionization process of 4p→εd according to present Dirac-Slater calculation. In the energy region of 4s autoionization, we have observed several features that are absent in previous fast-electron-impact work, but exist in optical measurements. We clarify this discrepancy here. Two Rydberg series of optically forbidden transitions, i.e., 4s -1 ns( 1 S) (n=5,6,7) and 4s -1 nd( 1 D) (n=4,5,6,7) have been observed when the spectrometer worked at conditions with larger momentum transfers, namely, K 2 =0.23 a.u. and 0.67 a.u. Furthermore, the absolute optical oscillator strengths for the 3d excitation have been obtained

  19. The Synthesis of the Hierarchical Structure of Information Resources for Management of Electronic Commerce Entities

    Directory of Open Access Journals (Sweden)

    Krutova Anzhelika S.

    2017-06-01

    Full Text Available The aim of the article is to develop the theoretical bases for the classification and coding of economic information and the scientific justification of the content of information resources of an electronic commerce enterprise. The essence of information resources for management of electronic business entities is investigated. It is proved that the organization of accounting in e-commerce systems is advisable to be built on the basis of two circuits: accounting for financial flows and accounting associated with transformation of business factors in products and services as a result of production activities. There presented a sequence of accounting organization that allows to combine the both circuits in a single information system, which provides a possibility for the integrated replenishment and distributed simultaneous use of the e-commerce system by all groups of users. It is proved that the guarantee of efficient activity of the information management system of electronic commerce entities is a proper systematization of the aggregate of information resources on economic facts and operations of an enterprise in accordance with the management tasks by building the hierarchy of accounting nomenclatures. It is suggested to understand nomenclature as an objective, primary information aggregate concerning a certain fact of the economic activity of an enterprise, which is characterized by minimum requisites, is entered into the database of the information system and is to be reflected in the accounting system. It is proposed to build a database of e-commerce systems as a part of directories (constants, personnel, goods / products, suppliers, buyers and the hierarchy of accounting nomenclatures. The package of documents regulating the organization of accounting at an enterprise should include: the provision on the accounting services, the order on the accounting policy, the job descriptions, the schedules of information exchange, the report card and

  20. The colpitts oscillator family

    DEFF Research Database (Denmark)

    Lindberg, Erik; Murali, K.; Tamasevicius, A.

    A tutorial study of the Colpitts oscillator family defined as all oscillators based on a nonlinear amplifier and a three- terminal linear resonance circuit with one coil and two capacitors. The original patents are investigated. The eigenvalues of the linearized Jacobian for oscillators based...

  1. Bounded-oscillation Pushdown Automata

    Directory of Open Access Journals (Sweden)

    Pierre Ganty

    2016-09-01

    Full Text Available We present an underapproximation for context-free languages by filtering out runs of the underlying pushdown automaton depending on how the stack height evolves over time. In particular, we assign to each run a number quantifying the oscillating behavior of the stack along the run. We study languages accepted by pushdown automata restricted to k-oscillating runs. We relate oscillation on pushdown automata with a counterpart restriction on context-free grammars. We also provide a way to filter all but the k-oscillating runs from a given PDA by annotating stack symbols with information about the oscillation. Finally, we study closure properties of the defined class of languages and the complexity of the k-emptiness problem asking, given a pushdown automaton P and k >= 0, whether P has a k-oscillating run. We show that, when k is not part of the input, the k-emptiness problem is NLOGSPACE-complete.

  2. Terahertz Plasma Waves in Two Dimensional Quantum Electron Gas with Electron Scattering

    International Nuclear Information System (INIS)

    Zhang Liping

    2015-01-01

    We investigate the Terahertz (THz) plasma waves in a two-dimensional (2D) electron gas in a nanometer field effect transistor (FET) with quantum effects, the electron scattering, the thermal motion of electrons and electron exchange-correlation. We find that, while the electron scattering, the wave number along y direction and the electron exchange-correlation suppress the radiation power, but the thermal motion of electrons and the quantum effects can amplify the radiation power. The radiation frequency decreases with electron exchange-correlation contributions, but increases with quantum effects, the wave number along y direction and thermal motion of electrons. It is worth mentioning that the electron scattering has scarce influence on the radiation frequency. These properties could be of great help to the realization of practical THz plasma oscillations in nanometer FET. (paper)

  3. Ion Acoustic Waves in the Presence of Electron Plasma Waves

    DEFF Research Database (Denmark)

    Michelsen, Poul; Pécseli, Hans; Juul Rasmussen, Jens

    1977-01-01

    Long-wavelength ion acoustic waves in the presence of propagating short-wavelength electron plasma waves are examined. The influence of the high frequency oscillations is to decrease the phase velocity and the damping distance of the ion wave.......Long-wavelength ion acoustic waves in the presence of propagating short-wavelength electron plasma waves are examined. The influence of the high frequency oscillations is to decrease the phase velocity and the damping distance of the ion wave....

  4. Temperature and magnetic field effect on oscillations observed in GaInNAs/GaAs multiple quantum wells structures

    International Nuclear Information System (INIS)

    Khalil, H.M.; Mazzucato, S.; Ardali, S.; Celik, O.; Mutlu, S.; Royall, B.; Tiras, E.; Balkan, N.; Puustinen, J.; Korpijärvi, V.-M.; Guina, M.

    2012-01-01

    Highlights: ► We studied p-i-n GaInNAs MQW devices as function of temperature and magnetic field. ► Observed oscillations in the sample current–voltage curves at low temperature. ► Shift in oscillation position with magnetic field described by Landau level split. ► Resonant tunnelling and thermionic emission used to describe oscillations. - Abstract: The photoconductivity of p-i-n GaInNAs/GaAs multiple quantum well (MQW) mesa structures is investigated. When illuminated with photons at energy greater than the GaAs bandgap, a number of oscillations are observed in the current–voltage I–V characteristics. The amplitude and position of the oscillations is shown to depend upon the temperature, as well as upon the exciting wavelength and intensity. Due to the absence of the oscillations in the dark I–V and at temperatures above T = 200 K, we explain them in terms of photogenerated electrons escaping from quantum wells via tunnelling or thermionic emission. Magnetic fields up to B = 11 T were applied parallel to the planes of the QWs. A small voltage shift in the position of the oscillations was observed, proportional to the magnetic field intensity and dependent upon the temperature. Calculation of the Landau level energy separation (16 meV) agrees with the observed experimental data. Magneto-tunnelling spectroscopy probes in detail the nature of band- or impurity-like states responsible for resonances in first and second subbands, observing the I–V plot in dark condition and under illumination. The field-dependence of the amplitude of the oscillation peaks in I–V has the characteristic form of a quantum mechanical admixing effect. This enhancement is also probably due to the hole recombination with majority electrons tunnelling in the N-related states of the quantum wells.

  5. Temperature and magnetic field effect on oscillations observed in GaInNAs/GaAs multiple quantum wells structures

    Energy Technology Data Exchange (ETDEWEB)

    Khalil, H.M., E-mail: hkhalia@essex.ac.uk [School of Computer Science and Electronic Engineering, University of Essex, CO4 3SQ, Colchester (United Kingdom); Mazzucato, S. [School of Computer Science and Electronic Engineering, University of Essex, CO4 3SQ, Colchester (United Kingdom); Ardali, S.; Celik, O.; Mutlu, S. [Anadolu University, Faculty of Science, Department of Physics, Yunus Emre Campus 26470, Eskisehir (Turkey); Royall, B. [School of Computer Science and Electronic Engineering, University of Essex, CO4 3SQ, Colchester (United Kingdom); Tiras, E. [Anadolu University, Faculty of Science, Department of Physics, Yunus Emre Campus 26470, Eskisehir (Turkey); Balkan, N. [School of Computer Science and Electronic Engineering, University of Essex, CO4 3SQ, Colchester (United Kingdom); Puustinen, J.; Korpijaervi, V.-M.; Guina, M. [Optoelectronics Research Centre, Tampere University of Technology, Korkeakoulunkatu 10, FI-33720 Tampere (Finland)

    2012-06-05

    Highlights: Black-Right-Pointing-Pointer We studied p-i-n GaInNAs MQW devices as function of temperature and magnetic field. Black-Right-Pointing-Pointer Observed oscillations in the sample current-voltage curves at low temperature. Black-Right-Pointing-Pointer Shift in oscillation position with magnetic field described by Landau level split. Black-Right-Pointing-Pointer Resonant tunnelling and thermionic emission used to describe oscillations. - Abstract: The photoconductivity of p-i-n GaInNAs/GaAs multiple quantum well (MQW) mesa structures is investigated. When illuminated with photons at energy greater than the GaAs bandgap, a number of oscillations are observed in the current-voltage I-V characteristics. The amplitude and position of the oscillations is shown to depend upon the temperature, as well as upon the exciting wavelength and intensity. Due to the absence of the oscillations in the dark I-V and at temperatures above T = 200 K, we explain them in terms of photogenerated electrons escaping from quantum wells via tunnelling or thermionic emission. Magnetic fields up to B = 11 T were applied parallel to the planes of the QWs. A small voltage shift in the position of the oscillations was observed, proportional to the magnetic field intensity and dependent upon the temperature. Calculation of the Landau level energy separation (16 meV) agrees with the observed experimental data. Magneto-tunnelling spectroscopy probes in detail the nature of band- or impurity-like states responsible for resonances in first and second subbands, observing the I-V plot in dark condition and under illumination. The field-dependence of the amplitude of the oscillation peaks in I-V has the characteristic form of a quantum mechanical admixing effect. This enhancement is also probably due to the hole recombination with majority electrons tunnelling in the N-related states of the quantum wells.

  6. Controlling user access to electronic resources without password

    Science.gov (United States)

    Smith, Fred Hewitt

    2015-06-16

    Described herein are devices and techniques for remotely controlling user access to a restricted computer resource. The process includes pre-determining an association of the restricted computer resource and computer-resource-proximal environmental information. Indicia of user-proximal environmental information are received from a user requesting access to the restricted computer resource. Received indicia of user-proximal environmental information are compared to associated computer-resource-proximal environmental information. User access to the restricted computer resource is selectively granted responsive to a favorable comparison in which the user-proximal environmental information is sufficiently similar to the computer-resource proximal environmental information. In at least some embodiments, the process further includes comparing user-supplied biometric measure and comparing it with a predetermined association of at least one biometric measure of an authorized user. Access to the restricted computer resource is granted in response to a favorable comparison.

  7. Resolving the mystery of milliwatt-threshold opto-mechanical self-oscillation in dual-nanoweb fiber

    Directory of Open Access Journals (Sweden)

    J. R. Koehler

    2016-08-01

    Full Text Available It is interesting to pose the question: How best to design an optomechanical device, with no electronics, optical cavity, or laser gain, that will self-oscillate when pumped in a single pass with only a few mW of single-frequency laser power? One might begin with a mechanically resonant and highly compliant system offering very high optomechanical gain. Such a system, when pumped by single-frequency light, might self-oscillate at its resonant frequency. It is well-known, however, that this will occur only if the group velocity dispersion of the light is high enough so that phonons causing pump-to-Stokes conversion are sufficiently dissimilar to those causing pump-to-anti-Stokes conversion. Recently it was reported that two light-guiding membranes 20 μm wide, ∼500 nm thick and spaced by ∼500 nm, suspended inside a glass fiber capillary, oscillated spontaneously at its mechanical resonant frequency (∼6 MHz when pumped with only a few mW of single-frequency light. This was surprising, since perfect Raman gain suppression would be expected. In detailed measurements, using an interferometric side-probing technique capable of resolving nanoweb movements as small as 10 pm, we map out the vibrations along the fiber and show that stimulated intermodal scattering to a higher-order optical mode frustrates gain suppression, permitting the structure to self-oscillate. A detailed theoretical analysis confirms this picture. This novel mechanism makes possible the design of single-pass optomechanical oscillators that require only a few mW of optical power, no electronics nor any optical resonator. The design could also be implemented in silicon or any other suitable material.

  8. Beta Beams: an accelerator based facility to explore Neutrino oscillation physics

    CERN Document Server

    Wildner, E; Hansen, C; De Melo Mendonca, T; Stora, T; Payet, J; Chance, A; Zorin, V; Izotov, I; Rasin, S; Sidorov, A; Skalyga, V; De Angelis, G; Prete, G; Cinausero, M; Kravchuk, VL; Gramegna, F; Marchi, T; Collazuol, G; De Rosa, G; Delbar, T; Loiselet, M; Keutgen, T; Mitrofanov, S; Lamy, T; Latrasse, L; Marie-Jeanne, M; Sortais, P; Thuillier, T; Debray, F; Trophime, C; Hass, M; Hirsh, T; Berkovits, D; Stahl, A

    2011-01-01

    The discovery that the neutrino changes flavor as it travels through space has implications for the Standard Model of particle physics (SM)[1]. To know the contribution of neutrinos to the SM, needs precise measurements of the parameters governing the neutrino oscillations. This will require a high intensity beam-based neutrino oscillation facility. The EURONu Design Study will review three currently accepted methods of realizing this facility (the so-called Super-Beams, Beta Beams and Neutrino Factories) and perform a cost assessment that, coupled with the physics performance, will give means to the European research authorities to make a decision on the layout and construction of the future European neutrino oscillation facility. ”Beta Beams” produce collimated pure electron neutrino and antineutrino beams by accelerating beta active ions to high energies and letting them decay in a race-track shaped storage ring. EURONu Beta Beams are based on CERNs infrastructure and the fact that some of the already ...

  9. Magnetically Coupled Magnet-Spring Oscillators

    Science.gov (United States)

    Donoso, G.; Ladera, C. L.; Martin, P.

    2010-01-01

    A system of two magnets hung from two vertical springs and oscillating in the hollows of a pair of coils connected in series is a new, interesting and useful example of coupled oscillators. The electromagnetically coupled oscillations of these oscillators are experimentally and theoretically studied. Its coupling is electromagnetic instead of…

  10. Terahertz radiation induced chaotic electron transport in semiconductor superlattices with a tilted magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Wang, C., E-mail: cwang@mail.sim.ac.cn; Wang, F.; Cao, J. C., E-mail: jccao@mail.sim.ac.cn [Key Laboratory of Terahertz Solid-State Technology, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, 865 Changning Road, Shanghai 200050 (China)

    2014-09-01

    Chaotic electron transport in semiconductor superlattice induced by terahertz electric field that is superimposed on a dc electric field along the superlattice axis are studied using the semiclassical motion equations including the effect of dissipation. A magnetic field that is tilted relative to the superlattice axis is also applied to the system. Numerical simulation shows that electrons in superlattice miniband exhibit complicate nonlinear oscillating modes with the influence of terahertz radiation. Transitions between frequency-locking and chaos via pattern forming bifurcations are observed with the varying of terahertz amplitude. It is found that the chaotic regions gradually contract as the dissipation increases. We attribute the appearance of complicate nonlinear oscillation in superlattice to the interaction between terahertz radiation and internal cooperative oscillating mode relative to Bloch oscillation and cyclotron oscillation.

  11. Terahertz radiation induced chaotic electron transport in semiconductor superlattices with a tilted magnetic field

    International Nuclear Information System (INIS)

    Wang, C.; Wang, F.; Cao, J. C.

    2014-01-01

    Chaotic electron transport in semiconductor superlattice induced by terahertz electric field that is superimposed on a dc electric field along the superlattice axis are studied using the semiclassical motion equations including the effect of dissipation. A magnetic field that is tilted relative to the superlattice axis is also applied to the system. Numerical simulation shows that electrons in superlattice miniband exhibit complicate nonlinear oscillating modes with the influence of terahertz radiation. Transitions between frequency-locking and chaos via pattern forming bifurcations are observed with the varying of terahertz amplitude. It is found that the chaotic regions gradually contract as the dissipation increases. We attribute the appearance of complicate nonlinear oscillation in superlattice to the interaction between terahertz radiation and internal cooperative oscillating mode relative to Bloch oscillation and cyclotron oscillation

  12. Terahertz radiation induced chaotic electron transport in semiconductor superlattices with a tilted magnetic field.

    Science.gov (United States)

    Wang, C; Wang, F; Cao, J C

    2014-09-01

    Chaotic electron transport in semiconductor superlattice induced by terahertz electric field that is superimposed on a dc electric field along the superlattice axis are studied using the semiclassical motion equations including the effect of dissipation. A magnetic field that is tilted relative to the superlattice axis is also applied to the system. Numerical simulation shows that electrons in superlattice miniband exhibit complicate nonlinear oscillating modes with the influence of terahertz radiation. Transitions between frequency-locking and chaos via pattern forming bifurcations are observed with the varying of terahertz amplitude. It is found that the chaotic regions gradually contract as the dissipation increases. We attribute the appearance of complicate nonlinear oscillation in superlattice to the interaction between terahertz radiation and internal cooperative oscillating mode relative to Bloch oscillation and cyclotron oscillation.

  13. Entanglement in a QFT Model of Neutrino Oscillations

    International Nuclear Information System (INIS)

    Illuminati, F.; Blasone, M.; Dell’Anno, F.; De Siena, S.

    2014-01-01

    Tools of quantum information theory can be exploited to provide a convenient description of the phenomena of particle mixing and flavor oscillations in terms of entanglement, a fundamental quantum resource. We extend such a picture to the domain of quantum field theory where, due to the nontrivial nature of flavor neutrino states, the presence of antiparticles provides additional contributions to flavor entanglement. We use a suitable entanglement measure, the concurrence, that allows extracting the two-mode (flavor) entanglement from the full multimode, multiparticle flavor neutrino states

  14. Rapidly tunable continuous-wave optical parametric oscillator pumped by a fiber laser

    NARCIS (Netherlands)

    Klein, M.E.; Gross, P.; Boller, Klaus J.; Auerbach, M.; Wessels, P.; Fallnich, C.

    2003-01-01

    We report on rapid, all-electronically controlled wavelength tuning of a continuous-wave (cw) optical parametric oscillator (OPO) pumped by an ytterbium fiber laser. The OPO is singly resonant for the signal wave and consists of a 40-mm-long periodically poled lithium niobate crystal in a

  15. Optically detected SdH oscillations in CdTe/(CdMg)Te and CdTe/(CdMnMg)Te modulation doped quantum wells

    Energy Technology Data Exchange (ETDEWEB)

    Shen, J.X.; Ossau, W.; Fischer, F.; Waag, A.; Landwehr, G. [Physikalisches Institut der Uniwersitaet Wuerzburg, Wuerzburg (Germany)

    1995-12-31

    Oscillations of photoluminescence properties in external magnetic fields are investigated in CdTe modulation doped quantum wells. The oscillatory behaviour of the luminescence intensity, the line width and the g factor is due to many-body effects in the 2-dimensional electron gas. The oscillation of photoluminescence intensity can be easily used as optically detected Shubnikov de Haas effect to determine the electron concentration in quantum wells without contacts. (author). 5 refs, 3 figs, 1 tab.

  16. First Detection of Low Energy Electron Neutrinos in Liquid Argon Time Projection Chambers

    Energy Technology Data Exchange (ETDEWEB)

    Adams, Corey James [Yale U.

    2016-01-01

    Electron neutrino appearance is the signature channel to address the most pressing questions in neutrino oscillations physics, at both long and short baselines. This includes the search for CP violation in the neutrino sector, which the U.S. flagship neutrino experiment DUNE will address. In addition, the Short Baseline Neutrino Program at Fermilab (MicroBooNE, SBND, ICARUS-T600) searches for new physics, such as sterile neutrinos, through electron neutrino appearance. Liquid argon time projection chambers are the forefront of neutrino detection technology, and the detector of choice for both short and long baseline neutrino oscillation experiments. This work presents the first experimental observation and study of electron neutrinos in the 1-10 GeV range, the essential oscillation energy regime for the above experiments. The systematic uncertainties for an electron neutrino appearance search for the Fermilab Short Baseline Neutrino Program are carefully quantified, and the characterization of separation between electrons and high energy photons is examined.

  17. Electronic theses and dissertations: a review of this valuable resource for nurse scholars worldwide.

    Science.gov (United States)

    Goodfellow, L M

    2009-06-01

    A worldwide repository of electronic theses and dissertations (ETDs) could provide worldwide access to the most up-to-date research generated by masters and doctoral students. Until that international repository is established, it is possible to access some of these valuable knowledge resources. ETDs provide a technologically advanced medium with endless multimedia capabilities that far exceed the print and bound copies of theses and dissertations housed traditionally in individual university libraries. CURRENT USE: A growing trend exists for universities worldwide to require graduate students to submit theses or dissertations as electronic documents. However, nurse scholars underutilize ETDs, as evidenced by perusing bibliographic citation lists in many of the research journals. ETDs can be searched for and retrieved through several digital resources such as the Networked Digital Library of Theses and Dissertations (http://www.ndltd.org), ProQuest Dissertations and Theses (http://www.umi.com), the Australasian Digital Theses Program (http://adt.caul.edu.au/) and through individual university web sites and online catalogues. An international repository of ETDs benefits the community of nurse scholars in many ways. The ability to access recent graduate students' research electronically from anywhere in the world is advantageous. For scholars residing in developing countries, access to these ETDs may prove to be even more valuable. In some cases, ETDs are not available for worldwide access and can only be accessed through the university library from which the student graduated. Public access to university library ETD collections is not always permitted. Nurse scholars from both developing and developed countries could benefit from ETDs.

  18. High-efficiency free-electron laser results

    International Nuclear Information System (INIS)

    Boyer, K.; Baru, C.A.; Newnam, B.E.; Stein, W.E.; Warren, R.W.; Winston, J.G.; Young, L.M.

    1983-01-01

    Results obtained with a tapered-wiggler free-electron laser demonstrate the concepts proposed by Morton for enhanced efficiency and show deceleration of electrons by as much as 7%, and extraction of more than 3% of the total electron-beam energy as laser energy when the laser is operated as an amplifier. The experiment is presently being reconfigured to examine its performance as a laser oscillator

  19. Experimental search for muon-neutrino oscillations and analysis of the simultaneous mixing of three neutrino flavors

    International Nuclear Information System (INIS)

    Bluemer, J.

    1985-01-01

    In the present thesis the experiment of the CDHS collaboration on the search for inclusive muon-neutrino oscillations is described. The event rates of ν μ reactions via charged currents was simultaneously measured in two detectors which were 130 m and 885 m away from the beam origin. The data contain no hints for oscillation effects. At maximal mixing mass differences of the contributing eigenstates are excluded in a range 0.26 ≤ Δm 2 ≤ 90 eV 2 with 90% confidence. The best sensitivity was reached for Δm 2 =2.5 eV 2 and allows there a maximal mixing parameter sin 2 2 ≤ 0.053. From the CDHS data the hitherto best limits on oscillation parameters resulted. From a common analysis of different oscillation experiments the allowed parameters for the case of simultaneous transitions between electron, muon, and tau neutrinos could be obtained. Regarding systematic uncertainties also here no evidence for oscillations exists. (orig./HSI) [de

  20. The g-u interference oscillations observed in the emission cross sections and the optical polarizations in He+-He collisions

    International Nuclear Information System (INIS)

    Tani, M.; Hishikawa, A.; Okasaka, R.

    1991-01-01

    We have observed emission radiation from helium atoms excited in He + -He collisions by the direct and electron capture processes over the energy range 0.5-20 keV. The relative emission cross sections for transitions 2 1,3 P-3 1,3 S, 2 1,3 S-3 1,3 P and 2 1,3 P-2 1,3 D have been determined. Degrees of optical polarization have also been determined for the P- and D-state excitations. The emission cross section of the direct excitation and that of the electron capture excitation show oscillations against impact energy, which are in antiphase with each other. The polarization degrees for both processes are nearly the same magnitude and show weak oscillations in antiphase with each other. The oscillations of the cross section and those of the polarization degree are in phase in some cases and in antiphase in other cases. These oscillations are interpreted as due to the interference between the gerade and ungerade states of the helium quasimolecular ion. From the amplitude ratio and the phase correlation between the oscillations of the cross section and those of the polarization degree we find that the predominant g-u interference pair is Π g -Π u . (author)