Showing papers on "Sine wave published in 2010"

Accuracy of Sine Wave Frequency Estimation by Multipoint Interpolated DFT Approach

Abstract: This paper focuses on the frequency-domain estimation of the normalized frequency of a sine wave corrupted by a stationary white noise. The weighted multipoint interpolated discrete Fourier transform method is considered, and its effect on both the spectral interference due to the image component and the additive wideband noise is taken into account. In particular, the expression of the combined standard uncertainty of the estimator is derived in the case when the H-term maximum sidelobe decay window (H ≥ 2) is used, and the number of interpolation points is 2J + 1 (J ≥ 1). Based on this expression, the number of interpolation points that minimize the estimator-combined uncertainty can be determined. The derived results are validated by means of computer simulations and applied to experimental data.

Sampling Piecewise Sinusoidal Signals With Finite Rate of Innovation Methods

Abstract: We consider the problem of sampling piecewise sinusoidal signals. Classical sampling theory does not enable perfect reconstruction of such signals since they are not band-limited. However, they can be characterized by a finite number of parameters, namely, the frequency, amplitude, and phase of the sinusoids and the location of the discontinuities. In this paper, we show that under certain hypotheses on the sampling kernel, it is possible to perfectly recover the parameters that define the piecewise sinusoidal signal from its sampled version. In particular, we show that, at least theoretically, it is possible to recover piecewise sine waves with arbitrarily high frequencies and arbitrarily close switching points. Extensions of the method are also presented such as the recovery of combinations of piecewise sine waves and polynomials. Finally, we study the effect of noise and present a robust reconstruction algorithm that is stable down to SNR levels of 7 [dB].

Spike morphology in blast-wave-driven instability experiments

Abstract: The laboratory experiments described in the present paper observe the blast-wave-driven Rayleigh–Taylor instability with three-dimensional (3D) initial conditions. About 5 kJ of energy from the Omega laser creates conditions similar to those of the He–H interface during the explosion phase of a supernova. The experimental target is a 150 μm thick plastic disk followed by a low-density foam. The plastic piece has an embedded, 3D perturbation. The basic structure of the pattern is two orthogonal sine waves where each sine wave has an amplitude of 2.5 μm and a wavelength of 71 μm. In some experiments, an additional wavelength is added to explore the interaction of modes. In experiments with 3D initial conditions the spike morphology differs from what has been observed in other Rayleigh–Taylor experiments and simulations. Under certain conditions, experimental radiographs show some mass extending from the interface to the shock front. Current simulations show neither the spike morphology nor the spike penetra...

Three-Dimensional Flux Vector Modulation of Four-Leg Sine-Wave Output Inverters

Abstract: The time integral of the output voltage vector of a three-phase inverter is often termed the inverter flux vector. This paper addresses the control of a three-phase four-leg sine-wave output inverter having an LC filter at its output, by controlling the flux vector in three dimensions. Flux vector control has the property that an output filter resonance is actively damped by an output voltage control loop alone. Furthermore, an inverter switching action inherently regulates the output voltage rapidly against dc-bus voltage variations. The flux vector control of sine-wave output inverters finds several applications in three-phase four-wire systems. This paper presents a flux modulation method for three-phase four-leg inverters feeding unbalanced and nonlinear loads. All the necessary steps for the digital implementation of the flux modulator are presented. The switching behavior of the modulator has been evaluated, which is useful for the variable fundamental frequency applications of the inverters. To provide experimental validation, the modulator is implemented as a part of the control system for a stand-alone three-phase four-leg inverter with an LC filter at its output. Control system details are also provided. Experimental results indicate the effectiveness of the modulator and control system in providing balanced voltages at the output of the LC filter even under highly unbalanced conditions with nonlinear loads. The resonance damping and voltage regulation properties of the modulator are also apparent from the experimental results.

The Membrane Potential Waveform of Bursting Pacemaker Neurons Is a Predictor of Their Preferred Frequency and the Network Cycle Frequency

Abstract: Many oscillatory networks involve neurons that exhibit intrinsic rhythmicity but possess a large variety of voltage-gated currents that interact in a complex fashion, making it difficult to determine which factors control frequency. Yet these neurons often have preferred (resonance) frequencies that can be close to the network frequency. Because the preferred frequency results from the dynamics of ionic currents, it can be assumed to depend on parameters that determine the neuron's oscillatory waveform shape. The pyloric network frequency in the crab Cancer borealis is correlated with the preferred frequency of its bursting pacemaker neurons anterior burster and pyloric dilator (PD). We measured the preferred frequency of the PD neuron in voltage clamp, which allows control of the oscillation voltage range and waveforms (sine waves and realistic oscillation waveforms), and showed that (1) the preferred frequency depends on the voltage range of the oscillating voltage waveform; (2) the slope of the waveform near its peak has a strongly negative correlation with the preferred frequency; and (3) correlations between parameters of the PD neuron oscillation waveform and its preferred frequency can be used to predict shifts in the network frequency. As predicted by these results, dynamic clamp shifts of the upper or lower voltage limits of the PD neuron waveform during ongoing oscillations changed the network frequency, consistent with the predictions from the preferred frequency. These results show that the voltage waveform of oscillatory neurons can be predictive of their preferred frequency and thus the network oscillation frequency.

Modulation of ultrasound to produce multifrequency radiation force

Abstract: Dynamic radiation force has been used in several types of applications, and is performed by modulating ultrasound with different methods By modulating ultrasound, energy can be transmitted to tissue, in this case a dynamic force to elicit a low frequency cyclic displacement to inspect the material properties of the tissue In this paper, different types of modulation are explored including amplitude modulation (AM), double sideband suppressed carrier amplitude modulation AM, linear frequency modulation, and frequency-shift keying Generalized theory is presented for computing the radiation force through the short-term time average of the energy density for these various types of modulation Examples of modulation with different types of signals including sine waves, square waves, and triangle waves are shown Using different modulating signals, multifrequency radiation force with different numbers of frequency components can be created, and can be used to characterize tissue mimicking materials and soft tissue Results for characterization of gelatin phantoms using a method of vibrating an embedded sphere are presented Different degrees of accuracy were achieved using different modulation techniques and modulating signals Modulating ultrasound is a very flexible technique to produce radiation force with multiple frequency components that can be used for various applications

Rotation angle sensor

Abstract: A rotation angle sensor comprises: a resolver stator including an excitation coil for receiving an excitation signal and a detection coil (a sine wave coil and a cosine wave coil) for outputting a detection signal; and a resolver rotor rotatably placed to face the stator. The resolver stator is formed on a stator flat plate. The resolver rotor is made of a flat-shaped rotor flat plate. The stator flat plate and the rotor flat plate are placed in parallel to face each other. The rotor flat plate is formed with a cutout.

Scalar PWM algorithms for four-switch three-phase inverters

Abstract: Four-switch three-phase inverters (FSTPIs) have been proposed to be used in low-cost applications because of the reduced number of semiconductor devices, and space vector pulse width modulation (SVPWM) techniques have also been introduced to control FSTPIs. However, high-performance controllers are needed to implement complicated SVPWM algorithms, which limits their low-cost applications. To simplify algorithms and reduce the cost of implementation, an equivalent scalar method for SVPWM of FSTPIs is proposed. SVPWM for FSTPIs is actually a sine PWM by modulating two sine waves of 60° phase difference with a triangle wave, so such a special sine PWM can be used to control FSTPIs. The simulation and experimental results demonstrate the validity of the proposed method.

Estimating Parameters of a Sine Wave by Separable Nonlinear Least Squares Fitting

Abstract: The four-parameter sine wave (FPSW) is commonly used to characterize noise, signal to noise, and the effective number of bits in analog-to-digital converters. An algorithm based on separable nonlinear least squares fitting is presented. In this algorithm, the frequency is the sole iterative variable. Numerical tests show that if the cycle in the record (CiR) is greater than 1, then the convergence is faster and is less dependent on the CiR and SNR. When the CiR is less than one, the convergence is significantly more sensitive to the CiR, the SNR, and the initial phase. Additionally, the lower the frequency, the more difficult the convergence.

Ground adaptive and optimized locomotion of snake robot moving with a novel gait

Abstract: In this paper, we present a novel gait, forward head serpentine (FHS), for a two dimensional snake robot. The advantage of this new gait is that the head link remains in the forward direction during motion. This feature significantly improves snake robot potential applications. Genetic Algorithm (GA) is used to find FHS gait parameters. Relationship between FHS gait parameters and friction coefficients of the ground are developed. Next, robot speed is considered in the optimization. A fitness function covering robot speed and head link angular changes is defined. A general sinusoidal wave form is applied for each joint. GA is used to find gait parameters resulting in maximum speed while head link angular changes remain in an acceptable range. Optimal gait parameters are also calculated for different friction coefficients and relationships between them are developed. Experiments are also performed using a 5-link snake robot. It is shown that experimental and theoretical results closely agree.

Influence of cancellous bone microstructure on two ultrasonic wave propagations in bovine femur: An in vitro study

Abstract: The influence of cancellous bone microstructure on the ultrasonic wave propagation of fast and slow waves was experimentally investigated. Four spherical cancellous bone specimens extracted from two bovine femora were prepared for the estimation of acoustical and structural anisotropies of cancellous bone. In vitro measurements were performed using a PVDF transducer (excited by a single sinusoidal wave at 1 MHz) by rotating the spherical specimens. In addition, the mean intercept length (MIL) and bone volume fraction (BV/TV) were estimated by X-ray micro-computed tomography. Separation of the fast and slow waves was clearly observed in two specimens. The fast wave speed was strongly dependent on the wave propagation direction, with the maximum speed along the main trabecular direction. The fast wave speed increased with the MIL. The slow wave speed, however, was almost constant. The fast wave speeds were statistically higher, and their amplitudes were statistically lower in the case of wave separation than in that of wave overlap.

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

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

Accurate Amplitude Estimation of Harmonic Components of Incoherently Sampled Signals in the Frequency Domain

Abstract: This paper focuses on estimating the amplitude of harmonic components of a harmonically distorted sine wave by the interpolated discrete Fourier transform (IpDFT) method with maximum sidelobe decay windows. The expression of the maximum of the interference error caused by the fundamental sine-wave component on the amplitude estimation of harmonic components is derived. In addition, for a signal corrupted by stationary white noise, the statistical efficiency of the IpDFT method is investigated with respect to the single-tone unbiased Crame?r-Rao lower bound (CRLB). Based on the derived expressions, a constraint is derived ensuring that interference from the fundamental component could practically be neglected. Finally, the performance of the IpDFT method is compared with that of the energy-based method on the basis of theoretical, simulation, and experimental results and with that of a state-of-the-art method according to simulation and experimental results.

Measurements of wind velocity and direction with coherent Doppler lidar in conditions of a weak echo signal

Abstract: The possibility of measuring the wind velocity and direction with 2-μm pulsed coherent Doppler lidar in conditions of a weak echo signal is investigated. It is shown that the use of the filtered sine wave fitting of the lidar-measured radial wind velocities allows for the estimation of the wind velocity vector components with an acceptable accuracy at a low signal-to-noise ratio up to values of −20 dB.

ADC linearity test signal generation algorithm

Abstract: This paper describes an algorithm for generating test signals to efficiently test the linearity of ADCs. Linearity is an important testing item for ADCs, and it takes a long time (hence is costly) to test low-sampling-rate, high-resolution ADCs. We here propose to generate a test signal consisting of multiple sine waves, to precisely test the linearity for specific important codes (such as around the center of the output codes), using an arbitrary waveform generator (AWG) and an analog filter. We have performed MATLAB simulation to validate our algorithm, and the results show that in some cases the testing time can be reduced to half that for conventional sine wave histogram testing.

Electric field statistics and modulation characteristics of bursty Langmuir waves observed in the cusp

Abstract: [1] HF wave receivers on the Twin Rockets to Investigate Cusp Electrodynamics (TRICE) detect numerous 20–250 ms duration Langmuir wave bursts. Investigation of 41 bursts at 967–984 km, where the gyrofrequency exceeds the plasma frequency, reveals a characteristic signature whereby the Langmuir wave bandwidth and highest frequency maximize at the center of the bursts, suggesting that bursts coincide with density enhancements. The Langmuir waveforms are modulated at frequencies up to 50 kHz, with significant modulation at frequencies <1 kHz about 10% of the time. Where amplitudes of the modulated waves pass through zero, the phase of the carrier wave shifts by 180°, consistent with a superposition of interfering waves. The corresponding wave spectrum has multiple <1 kHz bandwidth peaks separated by <1–50 kHz. For no averaging, the wave E field statistics, dominated by the carrier Langmuir wave, show an E+1 dependence at small E fields as expected for rectified sine waves. For moderate averaging, the statistics, dominated by the envelope field, show a spectral index of ≈ +2 at small E fields, consistent with numerical simulations of independent stochastically driven waves. The wave statistics, absence of VLF waves, lack of transition in the modulation occurrence as a function of frequency, and tendency of the spread spectrum to cut off at the ambient plasma frequency outside the density enhancement associated with the wave burst suggest that linear growth and mixing of Langmuir modes provides a more natural explanation of modulated Langmuir waves than do wave-wave processes previously proposed, at least for cusp waves encountered by TRICE.

Three phase power generation from a plurality of direct current sources

Abstract: A direct current to pulse amplitude modulated (“PAM”) current converter, denominated a “PAMCC”, is connected to an individual source of direct current The PAMCC receives direct current and provides pulse amplitude modulated current at its three output terminals, wherein the current of each terminal is one hundred twenty degrees out of phase with the other two terminals The pulses are produced at a high frequency relative to the signal modulated on a sequence of pulses The signal modulated onto a sequence of pulses may represent portions of a lower frequency sine wave or other lower frequency waveform, including DC When each phased output is connected in parallel with the outputs of similar PAMCCs an array of PAMCCs is formed, wherein each voltage phased output pulse is out of phase with respect to a corresponding current output pulse of the other PAMCCs An array of PAMCCs constructed in accordance with the present invention form a distributed three-phase multiphase inverter whose combined output is the demodulated sum of the current pulse amplitude modulated by each PAMCC on each phase

Three-Dimensionally Nonorthogonal Alternating-Direction Implicit Finite-Difference Time-Domain Algorithm for the Full-Wave Analysis of Microwave Monolithic Circuit Devices

Abstract: An alternating-direction implicit finite-difference time-domain (FDTD) algorithm is applied to the full wave analysis of microwave integrated circuit devices. A 3-D multidomain method is developed in nonorthogonal coordinates. Nonorthogonal grids are only used for the anomalistic regions of a complex structure, whereas the standard FDTD lattice is used for the other regions. By using the Jacobian coordinate transformation, curvilinear coordinates can be converted into conventional FDTD format expediently. The perfectly matched layer is used to truncate the boundary. Accurate griddings using the new scheme are obtained, and the complexity of the algorithm is minimal. To illustrate the theory, a sinusoidal plane wave and a Gaussian pulse that propagate through a localized nonorthogonal grid space is used, and the stability of our code is examined. A newly developed compact microstrip bandpass filter is analyzed using the proposed method. The simulated results agree very well with measurements. As compared to other nonorthogonal FDTD (NFDTD) method, the proposed algorithm is much more efficient than other NFDTD counterpart when complex structures are analyzed.

Resolver signal conversion device and method

Abstract: In a resolver signal conversion device and method, a sinusoidal output from a resolver is amplified and analog-digital converted, then the result is passed through a bandpass filter whereby a frequency component of a given frequency band having the frequency of the excitation signal as a center frequency is picked up, sampling is performed in synchronization with a reference signal based on said excitation signal, and a sine value of the detection angular signal is created on the basis of this sampled signal. Similarly, a cosine value of the detection angular signal is created on the basis of a cosine wave output from the resolver and a detection angle is calculated on the basis of the sine value and the cosine value of the detection angular signal. Thus, the inputted resolver signal is prevented from being affected by disturbance noise such as a magnetic field generated by a motor, switching noise due to PWM drive and the like, frequency dependency in processing is eliminated, thereby reducing errors in the detection angle.

Gaussian Jitter-Induced Bias of Sine Wave Amplitude Estimation Using Three-Parameter Sine Fitting

Abstract: In this paper, the bias on the estimated amplitude, which is caused by Gaussian jitter, is studied in case of the IEEE 1057 standard three-parameter sine-fitting method. Because no analytical study exists, this source of uncertainty is usually not considered. Nowadays, it is becoming more and more important due to the ever increasing sampling rates available in analog-to-digital converters (ADCs), which are used in innumerable application like high-speed digital oscilloscopes. The effect of additive noise is also taken into account.

Prediction and Modeling of Thin Gate Oxide Breakdown Subject to Arbitrary Transient Stresses

Abstract: A reliable dielectric breakdown model under transient stresses via an extension of the power law is demonstrated. The model, which is based on the percolation model and the assumption of no significant detrapping, is successfully used in ramped voltage stress breakdown analysis. A demonstration of the model's validity consists of applying repetitive time-variant voltage waveforms-pulses, sine waves, ramps, and noise-until breakdown and, consequently, comparing prediction to reality. The breakdown distribution is initially derived from DC measurements, with the model predicting both the center and the shape of the distribution.

Power conditioner and solar photovoltaic power generation system

Abstract: A first circuit generates a first sequence of square wave voltages having a voltage level that changes to a positive side relative to a first reference potential, which is a potential on a negative-electrode side of a direct current power source, from a direct current voltage. A second circuit generates a second sequence of square wave voltages having a voltage level lower than the voltage level of the first sequence of square wave voltages on the positive side that changes to a negative side relative to a second reference potential. The second chopper circuit further generates a third sequence of square wave voltages having a voltage level that changes to the positive and negative side in turns in the manner of sinusoidal wave relative to the first reference potential by summing the first sequence of square wave voltages and the second sequence of square wave voltages. A third circuit outputs the third sequence of square wave voltages as a charge/discharge output. The third circuit further PWM-controls the charge/discharge output so that a difference of the third sequence of square wave voltages to a sinusoidal wave voltage is corrected and thereby generates a sinusoidal wave voltage that continuously changes to the positive and negative sides relative to the first reference potential from the third sequence of square wave voltages and the PWM-controlled output, and outputs the generated sinusoidal wave voltage to a load.

Use of square waves incident on magnetic nanoparticles to induce magnetic hyperthermia for therapeutic cancer treatment

Abstract: Magnetic hyperthermia for treatment of tumors would benefit greatly from increased heating of the magnetic particles relative to the incident electromagnetic wave power. Micromagnetic simulations including thermal fluctuations show that the use of an incident square wave, as opposed to the usual sine wave, increases the normalized heat by at least 50%, with the possibility of much greater improvement for the usual case of particle ensembles that have a distribution of magnetic anisotropies, volumes, and angles to the incident radiation. It is shown that even replacement of the square wave by a limited number of harmonics is highly beneficial.

Maximum likelihood estimation of ADC Parameters

Abstract: Dynamic testing of analog-digital converters (ADC) is a complex task. A possible approach is using a sine wave because it can be generated with high precision. However, in the sine wave fitting method for the test of ADC's, all the available information is extracted from the measured data. Therefore, the estimated ADC parameters (ENOB, linearity errors) are not always accurate enough, and not detailed information is gained about the nonlinearity of the AD

Output-less transistor UPS

Abstract: This invention discloses a UPS without any output transformer including an input circuit, a rectification circuit composed of switches and inputting industrial frequency AC power and finishing boosting and rectification function by the input circuit, a DC bus, an inverse circuit connected to the rectification circuit by the DC bus and inverting stable sine waves, an output circuit outputting the sine wave to the load, in which, it has no exterior input and output midline, the input terminal of the input circuit is composed of two or three phase line voltage input voltages and the output of the output circuit is also composed of two or three-phase line voltage terminals.