Filter Results
757 results
Classically, the tendency towards spontaneous synchronization is strongest if the natural frequencies of the self-oscillators are as close as possible. We show that this wisdom fails in the deep quantum regime, where the uncertainty of amplitude narrows down to the level of single quanta. Under these circumstances identical self-oscillators cannot synchronize and detuning their frequencies can actually help synchronization. The effect can be understood in a simple picture: Interaction requires an exchange of energy. In the quantum regime, the possible quanta of energy are discrete. If the extractable energy of one oscillator does not exactly match the amount the second oscillator may absorb, interaction, and thereby synchronization, is blocked. We demonstrate this effect, which we coin quantum synchronization blockade, in the minimal example of two Kerr-type self-oscillators and predict consequences for small oscillator networks, where synchronization between blocked oscillators can be mediated via a detuned oscillator. We also propose concrete implementations with superconducting circuits and trapped ions. This paves the way for investigations of new quantum synchronization phenomena in oscillator networks both theoretically and experimentally.
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Quadrature Oscillator
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This paper describes a novel method for composing andimprovisation with real-time chaotic oscillators. Recentlydiscovered algebraically simple nonlinear third-order differential equations are solved and acoustical descriptors relating to their frequency spectrums are determined accordingto the MPEG-7 specification. A second nonlinearity is thenadded to these equations: a real-time audio signal. Descriptive properties of the complex behaviour of these equationsare then determined as a function of difference tones derived from a Just Intonation scale and the amplitude ofthe audio signal. By using only the real-time audio signalfrom live performer/s as an input the causal relationshipbetween acoustic performance gestures and computer output, including any visual or performer-instruction output,is deterministic even if the chaotic behaviours are not.
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spike frequency adaptation... oscillations
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CMOS LC-based oscillator
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A new low-cost test approach is proposed for testing embedded RF passive filters (ERPFs) by one-port measurement. By this method, ERPFs testing is possible without a vector network analyzer. This method also enables testing of ERPFs without external test stimulus. In the proposed test approach, a shift in the oscillation frequency of the test-setup is used to detect faults in the filters, but this test approach does not require reconfiguration or conversion of filters into an oscillator as it is done in conventional oscillation-based methods. The core principle of the method is to include an ERPF through a one-port substrate surface probe into an external RF oscillator circuitry, located on the probe card. Such one-port probing causes a change in the oscillation frequency of the oscillator because of the loading from the RF filter, thus enabling low-cost testing of RF filters.
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This paper describes a 2.4 GHz passive switch mixer and a 5/2.5 GHz voltage-controlled negative Gm oscillator (VCO) with an inversion-mode MOS varactor. Both circuits are implemented using a 1P8M 0.13 μm process. The switch mixer has an input referred 1 dB compression point of -3.89 dBm and a conversion gain of -0.96 dB when the local oscillator power is +2.5 dBm. The VCO consumes only 1.75 mW, while drawing 1.45 mA from a 1.2 V supply voltage. In order to reduce the passives size, the VCO natural oscillation frequency is 5 GHz. A clocked CMOS divideby- two circuit is used for frequency division and quadrature phase generation. The VCO has a -109 dBc/Hz phase noise at 1 MHz frequency offset and a 2.35-2.5 GHz tuning range (after the frequency division), thus complying with ZigBee requirements.
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After the publication of this work [1], we became aware of the fact that the frequency of the ultrasound transmitter that we used for determining the elastic moduli of the trabecular bone specimens was not correctly specified. The oscillation frequency of the ultrasound transmitter was 2 MHz (and not 100 MHz as stated in our work) while we used a sampling rate of 100 MHz. In our publication, the oscillation frequency and sampling rate were confounded. Therefore also the statement in the discussion that we might have determined elastic moduli of trabecular bone tissue rather than the elastic properties of whole specimens because we used an ultrasound frequency > 2 MHz is wrong and has to be omitted.
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Since January 2004 the High Resolution Stereo Camera (HRSC) is mapping planet Mars. The multi-line sensor on board the ESA Mission Mars Express images the Martian surface with a resolution of up to 1 2 m per pixel in three dimensions and in color. As part of the Photogrammetric/Cartographic Working Group of the HRSC Science Team the Institute of Photogrammetry and GeoInformation (IPI) of the Leibniz Universitat Hannover is involved in photogrammetrically processing the HRSC image data. To derive high quality 3D surface models, color orthoimages or other products, the accuracy of the observed position and attitude information in many cases should be improved. This is carried out via a bundle adjustment. In a considerable number of orbits the results of the bundle adjustment are disturbed by high frequency oscillations. This paper describes the impact of the high frequency angular spacecraft movement to the processing results of the last seven years of image acquisition and how the quality of the HRSC data products is significantly improved by modeling these oscillations.
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Oscillations are present both in natural speech and in the brain. This may be more than a mere coincidence. Re-instating information in the theta-frequency band has been shown to remarkably improve intelligibility. Moreover, a recent theory has proposed the existence of an internal tracking mechanism that parses and decodes incoming speech at a theta rhythm. This study sought to clarify the importance of theta-frequency band oscillations for speech comprehension as well as to establish their significance as a speech processing mechanism in the human auditory cortex. Here, it is shown that exposure to information in the theta-frequency range can restore intelligibility to a degraded, previously unintelligible stimulus, producing an auditory pop-out effect. This effect was observed regardless of whether participants were exposed to the intact sentence in the auditory or the visual domain. Compressing or extending the presentation speed of the intact sentence reduced the size of the effect, except for an extension rate of 1.5 times the original speed. At a neural level, it was previously unknown whether theta oscillations in auditory regions are internally generated or merely reflect stimulus driven evoked responses. Electrocorticographical recordings from one clinical patient provide evidence for the existence of theta-frequency oscillations in auditory regions, specifically the superior temporal gyrus, which are internally generated and effectively track incoming speech.
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