### 25677 results for qubit oscillator frequency

Contributors: Weixiong Chen, Quanbin Zhao, Yingchun Wang, Palash Kumar Sen, Daotong Chong, Junjie Yan

Date: 2016-09-01

Schematic diagram of steam jet [1–4].
...Submerged steam jet condensation is widely applied in various fields because of its high heat transfer efficiency. Condensation **oscillation** is a major character of submerged steam turbulent jet, and it significantly affects the design and safe operation of industrial equipment. This study is designed to reveal the mechanism of the low-**frequency** pressure **oscillation** of steam turbulent jet condensation and determine its affected region. First, pressure **oscillation** signals with low **frequency** are discovered in the downstream flow field through **oscillation** **frequency** spectrogram and power analysis. The **oscillation** **frequency** is even lower than the first dominant **frequency**. Moreover, the critical positions, where the low-**frequency** pressure **oscillation** signals appear, move downstream gradually with radial distance and water temperature. However, these signals are little affected by the steam mass flux. Then, the regions with low-**frequency** pressure **oscillation** occurring are identified experimentally. The affected width of the low-**frequency** pressure **oscillation** is similar to the turbulent jet width. Turbulent jet theory and the experiment results collectively indicate that the low-**frequency** pressure **oscillation** is generated by turbulent jet vortexes in the jet wake region. Finally, the angular coefficients of the low-**frequency** affected width are obtained under different water temperatures. Angular coefficients, ranging from 0.2268 to 0.2887, decrease with water temperature under test conditions....**Frequency** spectrograms distribution along the axial direction (R/D=2).
...**Frequency** spectrograms under radial position of R/D=3.0 and R/D=4.0.
...Half affected width of pressure **oscillation**.
...Submerged steam jet condensation is widely applied in various fields because of its high heat transfer efficiency. Condensation oscillation is a major character of submerged steam turbulent jet, and it significantly affects the design and safe operation of industrial equipment. This study is designed to reveal the mechanism of the low-**frequency** pressure oscillation of steam turbulent jet condensation and determine its affected region. First, pressure oscillation signals with low **frequency** are discovered in the downstream flow field through oscillation **frequency** spectrogram and power analysis. The oscillation **frequency** is even lower than the first dominant **frequency**. Moreover, the critical positions, where the low-**frequency** pressure oscillation signals appear, move downstream gradually with radial distance and water temperature. However, these signals are little affected by the steam mass flux. Then, the regions with low-**frequency** pressure oscillation occurring are identified experimentally. The affected width of the low-**frequency** pressure oscillation is similar to the turbulent jet width. Turbulent jet theory and the experiment results collectively indicate that the low-**frequency** pressure oscillation is generated by turbulent jet vortexes in the jet wake region. Finally, the angular coefficients of the low-**frequency** affected width are obtained under different water temperatures. Angular coefficients, ranging from 0.2268 to 0.2887, decrease with water temperature under test conditions....Frequency spectrograms under radial position of R/D=3.0 and R/D=4.0.
...Schematic diagram of experimental system [21].
...**Frequency** spectrograms of condensation **oscillation** [21].
...Oscillation power axial distribution for low frequency region.
...Half affected width of pressure oscillation.
...Pressure **oscillation**...**Oscillation** power axial distribution for low **frequency** region.
... Submerged steam jet condensation is widely applied in various fields because of its high heat transfer efficiency. Condensation **oscillation** is a major character of submerged steam turbulent jet, and it significantly affects the design and safe operation of industrial equipment. This study is designed to reveal the mechanism of the low-**frequency** pressure **oscillation** of steam turbulent jet condensation and determine its affected region. First, pressure **oscillation** signals with low **frequency** are discovered in the downstream flow field through **oscillation** **frequency** spectrogram and power analysis. The **oscillation** **frequency** is even lower than the first dominant **frequency**. Moreover, the critical positions, where the low-**frequency** pressure **oscillation** signals appear, move downstream gradually with radial distance and water temperature. However, these signals are little affected by the steam mass flux. Then, the regions with low-**frequency** pressure **oscillation** occurring are identified experimentally. The affected width of the low-**frequency** pressure **oscillation** is similar to the turbulent jet width. Turbulent jet theory and the experiment results collectively indicate that the low-**frequency** pressure **oscillation** is generated by turbulent jet vortexes in the jet wake region. Finally, the angular coefficients of the low-**frequency** affected width are obtained under different water temperatures. Angular coefficients, ranging from 0.2268 to 0.2887, decrease with water temperature under test conditions.

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Contributors: E. Il’ichev

Date: 2007-10-01

Dependence of the phase shift α on the two parameters ng and Φe. The **qubit** is irradiated by microwaves with a **frequency** of 8.0GHz. The periodic circular structure is due to the variation of the total interferometer-tank impedance caused by transitions from the lower to the upper energy band. The “crater ridges” (solid-line ellipse) correspond to all combinations of the parameters ng and Φe that give the same energy gap (8.0GHz) between the respective states [14].
...We present here recently obtained results with the theoretical and experimental investigations of charge-flux **qubits**. A charge-flux **qubit** consists of a single-Cooper-pair transistor closed by a superconducting loop. In this arrangement a **qubit** is effectively a tuneable two-level system. The **qubit** inductance was probed by a superconducting high-quality tank circuit. Under resonance irradiation, with a **frequency** of the order of the **qubit** energy level separation, change of the **qubit** inductance was observed. We have demonstrated that this effect is caused by the redistribution of the **qubit** level population. We have extracted from the measured data the energy gap of a **qubit** as a function of the quasicharge in the transistor island as well as the total Josephson phase difference across both junctions. The excitation of the **qubit** by one-, two-, and three-photon processes was detected. Quantitative agreement between theoretical predictions and experimental data was found. Relaxation as well as dephasing rates were reconstructed from the fitting procedure....Tank phase shift α dependence on gate parameter ng for different magnetic flux applied to the **qubit** loop . The data correspond to the flux Φ/Φ0=0.5, 0.53, 0.54, 0.56, 0.57. 0.61, 0.62, 0.65 (from bottom to top). For clarity, the upper curves are shifted.
...Experimentally observed dependence of the tank voltage phase shift α on the phase difference δ. The curves correspond to the fixed **frequency** Ω/2π=7.05GHz with the different power of the excitation (from bottom to top: -80, -60, -57(dB)). For clarity, the upper curves are shifted.
...Superconducting **qubits**...Experimental investigation of an interferometer type charge-flux **qubit**...Integrated design: Al **qubit** fabricated in the middle of the Nb coil (left-hand side), and single-Cooper-pair transistor (right-hand side).
...Left-hand side: tank phase shift α dependence on gate parameter ng without microwave power (lowest curve) and with microwave power at different excitation **frequencies**. The data correspond to the **frequency** of the microwave ΩMW/2π=8.9, 7.5, 6.0GHz (from top to bottom) [14]. Here the applied external magnetic flux was fixed Φdc=Φ0/2. For clarity, the upper curves are shifted. Right-hand side: energy gap Δ between the ground and upper states of the **qubit** determined from the experimental data for the case δ=π (Φdc=Φ0/2) [14]. The dots represent the experimental data, the solid line corresponds to the fit (cf. text).
...Calculated dependence of the tank voltage phase shift α on the phase difference δ. The curves correspond to the fixed **frequency** Ω/2π=7.05GHz with the different amplitude of the excitation (from bottom to top n˜g is: 0.1, 0.2, 0.4) [11]. For clarity, the upper curves are shifted.
... We present here recently obtained results with the theoretical and experimental investigations of charge-flux **qubits**. A charge-flux **qubit** consists of a single-Cooper-pair transistor closed by a superconducting loop. In this arrangement a **qubit** is effectively a tuneable two-level system. The **qubit** inductance was probed by a superconducting high-quality tank circuit. Under resonance irradiation, with a **frequency** of the order of the **qubit** energy level separation, change of the **qubit** inductance was observed. We have demonstrated that this effect is caused by the redistribution of the **qubit** level population. We have extracted from the measured data the energy gap of a **qubit** as a function of the quasicharge in the transistor island as well as the total Josephson phase difference across both junctions. The excitation of the **qubit** by one-, two-, and three-photon processes was detected. Quantitative agreement between theoretical predictions and experimental data was found. Relaxation as well as dephasing rates were reconstructed from the fitting procedure.

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Contributors: Václav Tesař

Date: 2014-01-01

Geometry of the diverter valve of the discussed oscillator in its initial design. Very similar – but not identical – to the design in the preliminary model, shown in Fig. 8.
...Depend...Measured **oscillation** **frequency** with different feedback tube lengths of the **oscillator** shown in Fig. 7, plotted as a function of the supplied flow rate. Surprisingly, the **frequency** is neither proportional to the flow rate (as is usual in the constant Strouhal-number **oscillators**, e.g., Tesař et al., 2006) – nor constant (as in the **oscillators** with resonator channel (Tesař et al., 2013)).
...Photograph of internal cavities of the integrated oscillator/aerator as used in the final experiments aimed at achieving high oscillation frequency. Note the absence of the “island” components as they are discussed in association with Figs. 5 and 11.
...Fluidic **oscillator**...Comparison of the oscillation in Fig. 17 and the basic frequency component L in Fig. 23. The replacement of the feedback channel loops by open areas for vortical flow made the feedback paths slightly shorter (and therefore the frequency higher).
...Results of measured dependence of **oscillation** **frequency** on the supplied flow rate in the layout shown in Figs. 20 and 12. Apart from basic **frequency** L, the output spectrum exhibited a much higher **frequency** component H.
...**Frequency** of generated **oscillation** plotted as a function of the air flow rate. Similarly as in Fig. 9 this dependence does not the fit the usual (constant Strouhal number) proportionality between **frequency** and flow rate.
...Measured oscillation frequency with different feedback tube lengths of the oscillator shown in Fig. 7, plotted as a function of the supplied flow rate. Surprisingly, the frequency is neither proportional to the flow **rate (as is** usual in the constant Strouhal-number oscillators, e.g., Tesař et al., 2006) – nor constant (as in the oscillators with resonator channel (Tesař et al., 2013)).
...Comparison of the oscillation in Fig. 17 and the basic **frequency** component L in Fig. 23. The replacement of the feedback channel loops by open areas for vortical flow made the feedback paths slightly shorter (and therefore the **frequency** higher)....Basic data on the geometry of the **oscillator** used in the high-**frequency** experiments.
...Microbubble generator excited by fluidic **oscillator's** third harmonic **frequency**...Comparison of the **oscillation** in Fig. 17 and the basic **frequency** component L in Fig. 23. The replacement of the feedback channel loops by open areas for vortical flow made the feedback paths slightly shorter (and therefore the **frequency** higher)....Efficient generation of sub-millimetre microbubbles was recently made possible by pulsating the flow of gas supplied into a parallel-exits aerator, using a fluidic **oscillator** for the purpose. Without moving parts, it can generate **oscillation** at high **frequency**, an important factor due to bubble natural **frequency** rapidly increasing with the desirable decrease of their size. This paper discusses development of an unusual **oscillator** – a part of an integral **oscillator**/aerator unit – capable of generating a particularly high driving **frequency**, in the kilohertz range, in a layout that promotes a strong third harmonic **frequency** of the basic **oscillation**....Detail photograph of the feedback channel entrances with the added sharp-edged “noses”.
...Efficient generation of sub-millimetre microbubbles was recently made possible by pulsating the flow of gas supplied into a parallel-exits aerator, using a fluidic **oscillator** for the purpose. Without moving parts, it can generate oscillation at high **frequency**, an important factor due to bubble natural **frequency** rapidly increasing with the desirable decrease of their size. This paper discusses development of an unusual **oscillator** – a part of an integral **oscillator**/aerator unit – capable of generating a particularly high driving **frequency**, in the kilohertz range, in a layout that promotes a strong third harmonic **frequency** of the basic oscillation....Dependence of bubble natural **oscillation** **frequency** on the size – based on the measurements in Tesař (2013b). The line is fitted for constant value of **oscillation** Weber number We0.
... Efficient generation of sub-millimetre microbubbles was recently made possible by pulsating the flow of gas supplied into a parallel-exits aerator, using a fluidic **oscillator** for the purpose. Without moving parts, it can generate **oscillation** at high **frequency**, an important factor due to bubble natural **frequency** rapidly increasing with the desirable decrease of their size. This paper discusses development of an unusual **oscillator** – a part of an integral **oscillator**/aerator unit – capable of generating a particularly high driving **frequency**, in the kilohertz range, in a layout that promotes a strong third harmonic **frequency** of the basic **oscillation**.

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Contributors: M.R. Qader

Date: 2013-01-01

ORIGINAL ARTICLE - Detuning effects in Haar wavelet spectrum of pulsed-driven **qubit**...Driven **qubit**...The transient scattered radiation due to interaction of a short laser pulse (of rectangular shape) with a **qubit** is studied through the Haar wavelet window spectrum. Asymmetrical structure in the spectrum is shown due to **frequency** miss-match of the laser and **qubit** **frequencies** and the shift window parameter. ... The transient scattered radiation due to interaction of a short laser pulse (of rectangular shape) with a **qubit** is studied through the Haar wavelet window spectrum. Asymmetrical structure in the spectrum is shown due to **frequency** miss-match of the laser and **qubit** **frequencies** and the shift window parameter.

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Contributors: Sven P. Heinrich, Michael Bach

Date: 2004-10-07

High-**frequency** oscillations in human visual cortex do not mirror retinal **frequencies**...High-**frequency** **oscillations**...Flash stimulation elicits oscillatory responses above 100 Hz in human visual cortex. It has been proposed that these are the result of retinal oscillations being directly relayed through the visual pathway to area V1. Experimental evidence, however, is scarce and contradictory. To address this issue, we performed a time–**frequency** analysis of simultaneously recorded retinal and cortical potentials. Matching **frequencies** would support the assumption of a direct relationship between retinal and cortical activities. In 4 of 7 subjects the **frequency** was significantly lower in the cortex than in the retina and in one subject it was significantly higher. The differences were in the range of 10–34 Hz and suggest that the cortical oscillations are not a simple echo of their retinal counterparts....Time–**frequency** distributions. On the left side, the full 20–1000 Hz range is displayed for three exemplary subjects. The two graphs per subject show the ERG and VEP activity, respectively. The high-**frequency** **oscillations** appear as a distinct area which in most cases is around or above 100 Hz. The flash was given at t=0. Those parts of the time–**frequency** diagram which would be contaminated by edge effects are displayed in white. Their spread is due to the inevitable **frequency**-dependent finite time resolution, which also causes the spurious pre-stimulus activity at low **frequencies**. The white rectangles in the diagrams mark the regions of interest, which are shown enlarged on the right side for all 7 subjects. The arrows link the high-**frequency** maxima of ERG and VEP. Most subjects produced activity around or above 100 Hz in both VEP and ERG. However, only in one subject (S1) the **frequencies** matched. Asterisks indicate the significance levels of **frequency** differences in standard notation, based on a sequential Bonferroni adjustment. No significance value could be obtained for subject S3.
...Time–**frequency** distributions. On the left side, the full 20–1000 Hz range is displayed for three exemplary subjects. The two graphs per subject show the ERG and VEP activity, respectively. The high-**frequency** oscillations appear as a distinct area which in most cases is around or above 100 Hz. The flash was given at t=0. Those parts of the time–**frequency** diagram which would be contaminated by edge effects are displayed in white. Their spread is due to the inevitable **frequency**-dependent finite time resolution, which also causes the spurious pre-stimulus activity at low **frequencies**. The white rectangles in the diagrams mark the regions of interest, which are shown enlarged on the right side for all 7 subjects. The arrows link the high-**frequency** maxima of ERG and VEP. Most subjects produced activity around or above 100 Hz in both VEP and ERG. However, only in one subject (S1) the **frequencies** matched. Asterisks indicate the significance levels of **frequency** differences in standard notation, based on a sequential Bonferroni adjustment. No significance value could be obtained for subject S3.
...High-**frequency** oscillations...Flash stimulation elicits oscillatory responses above 100 Hz in human visual cortex. It has been proposed that these are the result of retinal **oscillations** being directly relayed through the visual pathway to area V1. Experimental evidence, however, is scarce and contradictory. To address this issue, we performed a time–**frequency** analysis of simultaneously recorded retinal and cortical potentials. Matching **frequencies** would support the assumption of a direct relationship between retinal and cortical activities. In 4 of 7 subjects the **frequency** was significantly lower in the cortex than in the retina and in one subject it was significantly higher. The differences were in the range of 10–34 Hz and suggest that the cortical **oscillations** are not a simple echo of their retinal counterparts. ... Flash stimulation elicits oscillatory responses above 100 Hz in human visual cortex. It has been proposed that these are the result of retinal **oscillations** being directly relayed through the visual pathway to area V1. Experimental evidence, however, is scarce and contradictory. To address this issue, we performed a time–**frequency** analysis of simultaneously recorded retinal and cortical potentials. Matching **frequencies** would support the assumption of a direct relationship between retinal and cortical activities. In 4 of 7 subjects the **frequency** was significantly lower in the cortex than in the retina and in one subject it was significantly higher. The differences were in the range of 10–34 Hz and suggest that the cortical **oscillations** are not a simple echo of their retinal counterparts.

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Contributors: Hung-Chun Chien, Chih-Yen Chen

Date: 2014-02-01

Circuit diagram of the proposed DVCCTA-based variable** frequency** dual-mode sinusoidal oscillator.
...Simulation results of the current output Io for the variable** frequency** dual-mode sinusoidal oscillator (Fig. 4): (a) output waveform in the steady state** and (b) **the corresponding** frequency** spectrum.
...Simulation results of the current output Io for the single-resistance-controlled dual-mode sinusoidal oscillator (Fig. 3): (a) output waveform in the steady state** and (b) **corresponding** frequency** spectrum.
...**Oscillation** **frequency** against the bias current IB of the circuit shown in Fig. 4.
...CMOS realization of single-resistance-controlled and variable **frequency** dual-mode sinusoidal **oscillators** employing a single DVCCTA with all-grounded passive components...Sinusoidal **oscillator**...In this paper, two new designs are proposed for sinusoidal **oscillators** based on a single differential voltage current conveyor transconductance amplifier (DVCCTA). Each of the proposed circuits comprises a DVCCTA combined with passive components that simultaneously provides both voltage and current outputs. The first circuit is a DVCCTA-based single-resistance-controlled **oscillator** (SRCO) that provides independent control of the **oscillation** condition and **oscillation** **frequency** by using distinct circuit parameters. The second circuit is a DVCCTA-based variable **frequency** **oscillator** (VFO) that can provide independent control of the **oscillation** **frequency** by adjusting the bias current of the DVCCTA. In this paper, the DVCCTA and relevant formulations of the proposed **oscillator** circuits are first introduced, followed by the non-ideal effects, sensitivity analyses, **frequency** stability discussions, and design considerations. After using the 0.35-μm CMOS technology of the Taiwan Semiconductor Manufacturing Company (TSMC), the HSPICE simulation results confirmed the feasibility of the proposed **oscillator** circuits....Simulation results of the start-up **oscillations** of the variable **frequency** dual-mode sinusoidal **oscillator** (Fig. 4).
...In this paper, two new designs are proposed for sinusoidal **oscillators** based on a single differential voltage current conveyor transconductance amplifier (DVCCTA). Each of the proposed circuits comprises a DVCCTA combined with passive components that simultaneously provides both voltage and current outputs. The first circuit is a DVCCTA-based single-resistance-controlled **oscillator** (SRCO) that provides independent control of the oscillation condition and oscillation **frequency** by using distinct circuit parameters. The second circuit is a DVCCTA-based variable **frequency** **oscillator** (VFO) that can provide independent control of the oscillation **frequency** by adjusting the bias current of the DVCCTA. In this paper, the DVCCTA and relevant formulations of the proposed **oscillator** circuits are first introduced, followed by the non-ideal effects, sensitivity analyses, **frequency** stability discussions, and design considerations. After using the 0.35-μm CMOS technology of the Taiwan Semiconductor Manufacturing Company (TSMC), the HSPICE simulation results confirmed the feasibility of the proposed **oscillator** circuits....Circuit diagram of the proposed DVCCTA-based variable **frequency** dual-mode sinusoidal **oscillator**.
...Simulation results of the voltage **output Vo** for the variable** frequency** dual-mode sinusoidal oscillator (Fig. 4): (a) output waveform in the steady state** and (b) **the corresponding** frequency** spectrum.
...Variation of the **oscillation** **frequency** against R2 for the circuit (Fig. 3).
...Simulation results of the start-up oscillations of the variable** frequency** dual-mode sinusoidal oscillator (Fig. 4).
...Simulation results of the highest applicable **oscillations** of the variable **frequency** dual-mode sinusoidal **oscillator** (Fig. 4): (a) output waveform in the steady state; and (b) the start-up of the **oscillations**.
... In this paper, two new designs are proposed for sinusoidal **oscillators** based on a single differential voltage current conveyor transconductance amplifier (DVCCTA). Each of the proposed circuits comprises a DVCCTA combined with passive components that simultaneously provides both voltage and current outputs. The first circuit is a DVCCTA-based single-resistance-controlled **oscillator** (SRCO) that provides independent control of the **oscillation** condition and **oscillation** **frequency** by using distinct circuit parameters. The second circuit is a DVCCTA-based variable **frequency** **oscillator** (VFO) that can provide independent control of the **oscillation** **frequency** by adjusting the bias current of the DVCCTA. In this paper, the DVCCTA and relevant formulations of the proposed **oscillator** circuits are first introduced, followed by the non-ideal effects, sensitivity analyses, **frequency** stability discussions, and design considerations. After using the 0.35-μm CMOS technology of the Taiwan Semiconductor Manufacturing Company (TSMC), the HSPICE simulation results confirmed the feasibility of the proposed **oscillator** circuits.

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Contributors: Niko Bako, Adrijan Baric

Date: 2013-12-01

...**Oscillator**...Block scheme of the **oscillator**.
...Reference current and the oscillator frequency variations as a function of supply voltage and temperature obtained by simulations. (a) Reference current variation for typical (TT), slow (SS) and fast (FF) process corners with respect to the reference current at room temperature. (b) Frequency variation for typical, slow and fast corners with a supply voltage as a parameter with respect to frequency at room temperature.
...Miller compensated operational amplifier.
...Block scheme of the oscillator.
...Simulated open-loop AC characteristic of the amplifier.
...A low-power, temperature and supply voltage compensated current starved ring **oscillator**...Reference current and the **oscillator** **frequency** variations as a function of supply voltage and temperature obtained by simulations. (a) Reference current variation for typical (TT), slow (SS) and fast (FF) process corners with respect to the reference current at room temperature. (b) **Frequency** variation for typical, slow and fast corners with a supply voltage as a parameter with respect to **frequency** at room temperature.
...Si...A low-power, 3.82MHz **oscillator** based on a feedback loop is presented. The **oscillator** does not need a stable current reference to obtain a stable **frequency** independent of voltage and temperature variations because of the usage of negative feedback. The **frequency** variation, in the temperature range from −20°C to 80°C, is±0.6% and it depends only on the temperature coefficient of the resistor R, while the reference current variations are −11%/+25% in the same temperature range. The **oscillator** power consumption is 5.1μW and the active area is 0.09mm2. The proposed **oscillator** is implemented in a 0.18μm CMOS process and the simulation results are shown....The **oscillator** layout.
...Supply voltage compensated **frequency**...Simulated **oscillator** output.
...Temperature compensated **frequency** ... A low-power, 3.82MHz **oscillator** based on a feedback loop is presented. The **oscillator** does not need a stable current reference to obtain a stable **frequency** independent of voltage and temperature variations because of the usage of negative feedback. The **frequency** variation, in the temperature range from −20°C to 80°C, is±0.6% and it depends only on the temperature coefficient of the resistor R, while the reference current variations are −11%/+25% in the same temperature range. The **oscillator** power consumption is 5.1μW and the active area is 0.09mm2. The proposed **oscillator** is implemented in a 0.18μm CMOS process and the simulation results are shown.

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Contributors: György Buzsáki, Fernando Lopes da Silva

Date: 2012-09-01

Spontaneously occurring fast ‘ripple’ **oscillations** (400–500Hz) in the neocortex of the rat during high-voltage spindles. (A) Averaged high-voltage spindles and associated unit firing histograms from layers IV–VI. (B) Wide-band (a and a′; 1Hz–5kHz), filtered field (b and b′; 200–800Hz), and filtered unit (c and c′; 0.5–5kHz) traces from layers IV and V, respectively. (C) Averaged fast waves and corresponding unit histograms. The field ripples are filtered (200–800Hz) derivatives of the wide-band signals recorded from 16 sites. Note the sudden phase-reversal of the **oscillating** waves (arrows) but locking of unit discharges (dashed lines). These phase reversed dipoles likely reflect synchronous discharge of layer 5 neurons in the vicinity of the recording electrode.
...High **frequency** oscillations in the intact brain...Self-organized burst of activity in the CA3 region of the hippocampus produces a sharp wave sink in the apical dendrites of CA1 pyramidal neurons and also discharge interneurons. The interactions between the discharging pyramidal cells and interneurons give rise to a short-lived fast **oscillation** (‘ripple’; 140–200Hz), which can be detected as a field potential in the somatic layer. The strong CA1 population burst brings about strongly synchronized activity in the target populations of parahippocampal structures as well. These parahippocampal ripples are slower and less synchronous, compared to CA1 ripples.
...High **frequency** **oscillations** (HFOs) constitute a novel trend in neurophysiology that is fascinating neuroscientists in general, and epileptologists in particular. But what are HFOs? What is the **frequency** range of HFOs? Are there different types of HFOs, physiological and pathological? How are HFOs generated? Can HFOs represent temporal codes for cognitive processes? These questions are pressing and this symposium volume attempts to give constructive answers. As a prelude to this exciting discussion, we summarize the physiological high **frequency** patterns in the intact brain, concentrating mainly on hippocampal patterns, where the mechanisms of high **frequency** **oscillations** are perhaps best understood....High **frequency** oscillations (HFOs) constitute a novel trend in neurophysiology that is fascinating neuroscientists in general, and epileptologists in particular. But what are HFOs? What is the **frequency** range of HFOs? Are there different types of HFOs, physiological and pathological? How are HFOs generated? Can HFOs represent temporal codes for cognitive processes? These questions are pressing and this symposium volume attempts to give constructive answers. As a prelude to this exciting discussion, we summarize the physiological high **frequency** patterns in the intact brain, concentrating mainly on hippocampal patterns, where the mechanisms of high **frequency** oscillations are perhaps best understood. ... High **frequency** **oscillations** (HFOs) constitute a novel trend in neurophysiology that is fascinating neuroscientists in general, and epileptologists in particular. But what are HFOs? What is the **frequency** range of HFOs? Are there different types of HFOs, physiological and pathological? How are HFOs generated? Can HFOs represent temporal codes for cognitive processes? These questions are pressing and this symposium volume attempts to give constructive answers. As a prelude to this exciting discussion, we summarize the physiological high **frequency** patterns in the intact brain, concentrating mainly on hippocampal patterns, where the mechanisms of high **frequency** **oscillations** are perhaps best understood.

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Contributors: Yu.P. Emelianova, A.P. Kuznetsov, I.R. Sataev, L.V. Turukina

Date: 2013-02-01

Rotation numbers ν1–2 and ν2–3 versus the **frequency** detuning Δ1 for the system (11). Values of the parameters are λ1=1.3,λ2=1.9,λ3=1.8,Δ2=1.5 and μ=0.32.
...Schematic representation of a system of three coupled self-**oscillators**.
...The problem of growing complexity of the dynamics of the coupled phase **oscillators** as the number of **oscillators** in the chain increases is considered. The organization of the parameter space (parameter of the **frequency** detuning between the second and the first **oscillators** versus parameter of dissipative coupling) is discussed. The regions of complete synchronization, quasi-periodic regimes of different dimensions and chaos are identified. We discuss transformation of the domains of different dynamics as the number of **oscillators** grows. We use the method of charts of Lyapunov exponents and modification of the method of the chart of dynamical regimes to visualize two-**frequency** regimes of different type. Limits of applicability of the quasi-harmonic approximation and the features of the dynamics of the original system which are not described by the approximate phase equations are discussed for the case of three coupled **oscillators**....Subdivision of the chain of four oscillators by clusters for the three types of the phase locked pair of oscillators. Parameters are chosen in such a way that the system of oscillators is near the point of the saddle–node bifurcation.
...Trajectories on the phase torus. (a) resonant two-**frequency** regime with winding number w=1:2, (b) three-**frequency** regime.
...Trajectories on the phase torus. (a) resonant two-frequency regime with winding number w=1:2, (b) three-frequency regime.
...Synchronization and multi-**frequency** oscillations in the low-dimensional chain of the self-oscillators...(Color online). Chart of the Lyapunov’s exponents for the system of three coupled phase **oscillators** (5) for Δ2=1. The color palette is given and decrypted under the picture. The numbers indicate the tongues of the main resonant two-**frequency** regimes. These regimes are explained in the description of Fig. 5.
...(Color online). Chart of the Lyapunov’s exponents for the system of three coupled phase oscillators (5) for Δ2=1. The color palette is given and decrypted under the picture. The numbers indicate the tongues of the main resonant two-frequency regimes. These regimes are explained in the description of Fig. 5.
...Subdivision of the chain of four **oscillators** by clusters for the three types of the phase locked pair of **oscillators**. Parameters are chosen in such a way that the system of **oscillators** is near the point of the saddle–node bifurcation.
...(Color online). Charts of the Lyapunov’s exponents for the system of three coupled van der Pol oscillators (1). (a) λ=0.1,Δ2=0.05, (b) λ=0**.2,Δ2=0.15**. OD is a region of “oscillator death”. PBS is a region of partial broadband synchronization.
...Phase **oscillators**...Rotation numbers ν1–2 and ν2–3 versus the frequency detuning Δ1 for the system (11). Values of the parameters are λ1=1.3,λ2=1.9,λ3=1.8,Δ2=1.5 and μ=0.32.
... The problem of growing complexity of the dynamics of the coupled phase **oscillators** as the number of **oscillators** in the chain increases is considered. The organization of the parameter space (parameter of the **frequency** detuning between the second and the first **oscillators** versus parameter of dissipative coupling) is discussed. The regions of complete synchronization, quasi-periodic regimes of different dimensions and chaos are identified. We discuss transformation of the domains of different dynamics as the number of **oscillators** grows. We use the method of charts of Lyapunov exponents and modification of the method of the chart of dynamical regimes to visualize two-**frequency** regimes of different type. Limits of applicability of the quasi-harmonic approximation and the features of the dynamics of the original system which are not described by the approximate phase equations are discussed for the case of three coupled **oscillators**.

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Contributors: Uwe Starossek

Date: 2015-01-01

Free **oscillation** response of pendulum mechanism.
...Free **oscillation** response...Low **frequency**...A low-**frequency** pendulum mechanism...A pendulum mechanism is presented whose natural **frequency** of **oscillation** is distinctly lower than that of a conventional pendulum of comparable size. Furthermore, its natural **frequency** is approximately proportional to its amplitude of **oscillation**. The mechanism can thus be tuned to extremely low **frequencies** by using small amplitudes. The undamped free **oscillation** response of the mechanism is studied. The derivation of the equation of motion is outlined for both large and, after neglecting higher order terms, small displacements. In both cases, a second-order nonlinear differential equation results. When higher order terms are neglected, the equation of motion is of simple form and can be solved symbolically in terms of a Jacobi elliptic function. Based on this solution, a closed-form expression for the natural **frequency** is derived and the characteristics of the free **oscillation** response are discussed....A pendulum mechanism is presented whose natural **frequency** of oscillation is distinctly lower than that of a conventional pendulum of comparable size. Furthermore, its natural **frequency** is approximately proportional to its amplitude of oscillation. The mechanism can thus be tuned to extremely low **frequencies** by using small amplitudes. The undamped free oscillation response of the mechanism is studied. The derivation of the equation of motion is outlined for both large and, after neglecting higher order terms, small displacements. In both cases, a second-order nonlinear differential equation results. When higher order terms are neglected, the equation of motion is of simple form and can be solved symbolically in terms of a Jacobi elliptic function. Based on this solution, a closed-form expression for the natural **frequency** is derived and the characteristics of the free oscillation response are discussed. ... A pendulum mechanism is presented whose natural **frequency** of **oscillation** is distinctly lower than that of a conventional pendulum of comparable size. Furthermore, its natural **frequency** is approximately proportional to its amplitude of **oscillation**. The mechanism can thus be tuned to extremely low **frequencies** by using small amplitudes. The undamped free **oscillation** response of the mechanism is studied. The derivation of the equation of motion is outlined for both large and, after neglecting higher order terms, small displacements. In both cases, a second-order nonlinear differential equation results. When higher order terms are neglected, the equation of motion is of simple form and can be solved symbolically in terms of a Jacobi elliptic function. Based on this solution, a closed-form expression for the natural **frequency** is derived and the characteristics of the free **oscillation** response are discussed.

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