Showing papers on "Sine wave published in 2018"

A better way to define and describe Morlet wavelets for time-frequency analysis

Abstract: Morlet wavelets are frequently used for time-frequency analysis of non-stationary time series data, such as neuroelectrical signals recorded from the brain. The crucial parameter of Morlet wavelets is the width of the Gaussian that tapers the sine wave. This width parameter controls the trade-off between temporal precision and frequency precision. It is typically defined as the "number of cycles," but this parameter is opaque, and often leads to uncertainty and suboptimal analysis choices, as well as being difficult to interpret and evaluate. The purpose of this paper is to present alternative formulations of Morlet wavelets in time and in frequency that allow parameterizing the wavelets directly in terms of the desired temporal and spectral smoothing (as full-width at half-maximum). This formulation provides clarity on an important data analysis parameter, and should facilitate proper analyses, reporting, and interpretation of results. MATLAB code is provided.

Power System Frequency Estimation of Sine-Wave Corrupted With Noise by Windowed Three-Point Interpolated DFT

Abstract: This paper presents a symmetric three points IpDFT (S3IpDFT) method which can be associated with all combined cosine windows. The influence of spectral interference from image component and noise on the power system frequency estimation provided by the S3IpDFT is investigated. The expression for the absolute error of the normalized frequency caused by the spectral interference from image component is presented. Also, the analytical expression of the frequency estimation variance has been derived. The derived results are validated by means of computer simulations and experiments.

Power Quality Enhancement Using Current Injection Technique in a Zigzag Configured Autotransformer-Based 12-Pulse Rectifier

Abstract: This paper proposes a DC-side circuit configuration that improves the harmonic suppression ability of a 12-pulse diode bridge rectifier (DBR) using a zigzag configured autotransformer. The DC-side circuit uses a single-phase DBR along with interphase transformer which generates the required circulating current thereby modifies the DC currents at the DBR output, in turn shapes the input line current near to a sine wave. The proposed single-phase DBR is connected in parallel with the load which enables to reuse the harmonic energy thus improving the energy conversion efficiency. The zigzag configured autotransformer used for 12-pulse DBR possesses the inbuilt ability to hinder the zero-sequence components, which expel the need of zero sequence blocking transformer. The proposed configuration is analyzed, simulated in MATLAB Simulink and the simulation results are presented, which confirm the reduction of total harmonic distortion (THD) in the input line current thereby improving the power quality under large load variations. Furthermore, the viability of the proposed configuration is verified by experimental results, which confirm the suitability of the proposed configuration in industrial applications.

Basic Emission Waveform Theory: A Novel Interpretation and Source Identification Method for Electromagnetic Emission of Complex Systems

Abstract: Variable numerous types of equipment/subsystems may exist in complex systems, which makes it difficult to analyze and identify electromagnetic emission sources. A theory named “basic emission waveform theory” is presented in this paper to solve this problem. This innovation theory characterizes emission with four basic waveforms, including square wave, sine wave, damped oscillation, and spike wave. Then, the effectiveness of the theory is discussed in both theoretical and engineering ways. In particular, the basic waveforms reflect the physical characteristics of the equipment. Furthermore, the basic waveforms generally do not vary with the locations or loading conditions. Therefore, the identification and analysis of an emission source can be realized by analyzing the basic waveforms from the emission of a complex system. Finally, the applications of damped oscillation and square wave in emission source identification field are used as validations of the proposed theory. Moreover, an example of emission source identification for an electric vehicle is also presented. The examples show that the proposed theory can be used to simply and accurately identify and analyze the emission sources of complex systems.

Lagrangian Cosmological Perturbation Theory at Shell Crossing

Abstract: We consider the growth of primordial dark matter halos seeded by three crossed initial sine waves of various amplitudes. Using a Lagrangian treatment of cosmological gravitational dynamics, we examine the convergence properties of a high-order perturbative expansion in the vicinity of shell crossing by comparing the analytical results with state-of-the-art high resolution Vlasov-Poisson simulations. Based on a quantitative exploration of parameter space, we study explicitly for the first time the convergence speed of the perturbative series and find, in agreement with intuition, that it slows down when going from quasi-one-dimensional initial conditions (one sine wave dominating) to quasitriaxial symmetry (three sine waves with same amplitude). In most cases, the system structure at collapse time is, as expected, very similar to what is obtained with simple one-dimensional dynamics, except in the quasitriaxial regime, where the phase-space sheet presents a velocity spike. In all cases, the perturbative series exhibits a generic convergence behavior as fast as an exponential of a power law of the order of the expansion, allowing one to numerically extrapolate it to infinite order. The results of such an extrapolation agree remarkably well with the simulations, even at shell crossing.

Absolute and Precise Terahertz-Wave Radar Based on an Amplitude-Modulated Resonant-Tunneling-Diode Oscillator

Abstract: We present the principle of a terahertz-wave radar and its proof-of-concept experimental verification. The radar is based on a 522 GHz resonant-tunneling-diode oscillator, whose terahertz output power can be easily modulated by superimposing the modulation signal on its bias voltage. By using one modulation frequency and measuring the time delay of the returning signal, a relative measurement of the propagation distance is possible; adding a second modulation frequency removes the ambiguity stemming from the periodicity of the modulation sine wave and allows an absolute distance measurement. We verified this measurement method experimentally and obtained a submillimeter precision, as predicted by theory.

Study on W-band sheet-beam traveling-wave tube based on flat-roofed sine waveguide

Abstract: A W-band sheet electron beam (SEB) traveling-wave tube (TWT) based on flat-roofed sine waveguide slow-wave structure (FRSWG-SWS) is proposed. The sine wave of the metal grating is replaced by a flat-roofed sine wave around the electron beam tunnel. The slow-wave characteristics including the dispersion properties and interaction impedance have been investigated by using the eigenmode solver in the 3-D electromagnetic simulation software Ansoft HFSS. Through calculations, the FRSWG SWS possesses the larger average interaction impedance than the conventional sine waveguide (SWG) SWS in the frequency range of 86-110 GHz. The beam-wave interaction was studied and particle-in-cell simulation results show that the SEB TWT can produce output power over 120 W within the bandwidth ranging from 90 to 100 GHz, and the maximum output power is 226 W at typical frequency 94 GHz, corresponding electron efficiency of 5.89%.

Depth-integrated nonhydrostatic free-surface flow modeling using weighted-averaged equations

Abstract: Summary In this study, a depth-integrated nonhydrostatic flow model is developed using the method of weighted residuals. Using a unit weighting function, depth-integrated Reynolds-averaged Navier-Stokes equations are obtained. Prescribing polynomial variations for the field variables in the vertical direction, a set of perturbation parameters remains undetermined. The model is closed generating a set of weighted-averaged equations using a suitable weighting function. The resulting depth-integrated nonhydrostatic model is solved with a semi-implicit finite-volume finite-difference scheme. The explicit part of the model is a Godunov-type finite-volume scheme that uses the Harten-Lax-van Leer-contact wave approximate Riemann solver to determine the nonhydrostatic depth-averaged velocity field. The implicit part of the model is solved using a Newton-Raphson algorithm to incorporate the effects of the pressure field in the solution. The model is applied with good results to a set of problems of coastal and river engineering, including steady flow over fixed bedforms, solitary wave propagation, solitary wave run-up, linear frequency dispersion, propagation of sinusoidal waves over a submerged bar, and dam-break flood waves.

High-Purity Sine Wave Generation Using Nonlinear DAC With Predistortion Based on Low-Cost Accurate DAC–ADC Co-Testing

Abstract: Data converters are among the most widely used components in modern integrated devices and systems. A major challenge is to characterize their performances accurately and cost effectively. The analog-to-digital converter (ADC) standard test requires the input sinusoidal signal to be 3–4 b better than that of the ADC under test. Such high-quality sine waves are extremely difficult to generate and challenging to implement cost effectively. This paper presents a novel method that is capable of generating a high-purity sine wave using a nonlinear digital-to-analog converter (DAC), whose purity is significantly better than the original DAC output. In addition, with the aid of the low-cost DAC–ADC co-testing method, both DAC and ADC linearity information are accurately obtained with only 1 hit per code. Therefore, it is possible to add DAC linearity information to the DAC input codes, which cancels the nonlinearity of the DAC at output to achieve high purity. The proposed method has been validated by extensive simulation and measurement results, which demonstrated its accuracy and robustness against different resolutions, structures, or performance of the ADCs/DACs. With its low cost and easy test setup, such high-purity sine wave can be widely used for various applications where precision testing is required. In addition, the ADC and DAC linearity information is accurately obtained at the same time without any precision instrumentation, which is suitable for accurate DAC–ADC co-testing.

Amplitude and Phase Estimation of Real-Valued Sine Wave via Frequency-Domain Linear Least-Squares Algorithms

Abstract: This paper investigates the real-valued sine-wave amplitude and phase estimates returned by two frequency-domain linear least-squares (FLLSs) algorithms. Both algorithms are based on discrete-time Fourier transform samples evaluated at the sine-wave frequency in order to maximize the immunity to wideband noise. One of the analyzed procedures, called FLLS algorithm, is affected by the contribution of the spectral image component to the estimated parameters. The other one, called the enhanced-FLLS algorithm, compensates for this detrimental contribution, which is particularly significant when a small number of sine-wave cycles is observed. The image component interference compensation is obtained at the cost of a slightly higher computational effort and noise immunity. Closed-form relationships for both the analyzed estimators and their variances are provided. Analytical expressions for the estimators which avoid matrix operations are also derived under conditions of practical interest. Finally, the accuracies of the analyzed algorithms are compared with that of a state-of-the-art estimator based on the classical three-parameter sine-fit algorithm, through both theoretical and simulation results.

Critical Response of Single-Degree-of-Freedom Damped Bilinear Hysteretic System under Double Impulse As Substitute for Near-Fault Ground Motion

Abstract: A double impulse input is used as a substitute for near-fault earthquake ground motions. A closed-form expression is derived in the maximum elastic-plastic response of a single-degree-of-freedom (SDOF) damped structure with bilinear hysteresis under the ‘critical double impulse input’ which causes the maximum response for variable impulse interval with the input level kept constant. Since only the free-vibration exists under the double impulse, the energy balance approach for the kinetic energy, hysteretic and strain energies, and damping energy plays a key role in the derivation of the closed-form expression of a complicated damped bilinear hysteretic response. It is shown that the critical elastic-plastic deformation and the corresponding critical impulse timing can be derived depending on the input level. The accuracy of the proposed simplified but smart methodology is confirmed through the comparison with the response analysis to the critical double impulse and the corresponding one-cycle sine wave as a representative for the near-fault earthquake ground motion.

Systematic Reduction of Peak and Average Emissions of Power Electronic Converters by the Application of Spread Spectrum

Abstract: This paper deals with the application of spread spectrum techniques on power electronic converters to reduce electromagnetic disturbances. These techniques aim for a spreading of the harmonics in a frequency domain in order to distribute the power over a wider frequency range. By doing so, the levels of the harmonics drop. In this paper, both peak and average detector measurements are considered. It is shown that different parameters are required to minimize either peak or average emissions. The reduction of peak and/or average emissions is mathematically described for a sine wave as a harmonic of pulse width modulation signals. These spread harmonics overlap for high orders and/or high-frequency variations. It is shown that this effect is a limiting factor for spread spectrum in practical applications. The resulting maximum achievable reduction is analyzed. From these results, parametrization strategies are derived to fulfill specific requirements. In test setups, the precision of the proposed parametrization strategies is demonstrated. Additionally, it is shown that the results for peak measurements can also be applied to quasi-peak measurements.

Symmetrical Multilevel Cascaded H-Bridge Inverter Using Multicarrier SPWM Technique

Abstract: An efficient multicarrier SPWM for cascaded H-Bridge symmetrical multilevel inverter is discussed here. The performance output levels of the CHB MLI is depends on number of DC input voltage sources. If two DC sources are applied then it gives five levels at output and three DC sources gives seven levels of output. In this papermulticarrierSPWM switching is provided to the multilevel inverter switches. In this switching method two signals are used, one is reference and another is carrier signal. For SPWM technique reference signal is sine wave and triangular wave is carrier signal. This type of inverters have thecapability to produce waveforms with better harmonic spectrum and realistic output results. The results of the model shows that the THD is reduced with the modulation of sinusoidal pulse width. The simulation results shows that quality of output voltagewaveform gets improved with less loss as well as lower THD.

Design and real-time implementation of SPWM based inverter

Abstract: This paper presents the design and implementation of 1kW SPWM based inverter to convert the applied DC voltage from photovoltaic array in to pure sinusoidal AC voltage according to the voltage and frequency of standard grid output i-e 220V and 50Hz. The crux of this research work is the use of an economical and advanced 16-bit PIC microcontroller to generate the popular SPWM with very high carrier frequency (in order of kHz) to control the inverter circuit. The high frequency pulses of SPWM results in smoothed filtration of inverter output into pure sine wave by using small sized capacitors and inductors as a filter. In this paper, the simulations of inverter are presented by first developing code of SPWM in MPLAB and then simulating it on Proteus software. Finally, it is real-time implemented and tested for resistive load and the output voltage and current are displayed on LCD.

A 36-Pulse AC-DC Converter With DC Side Tapped Interphase Bridge Rectifier for Power Quality Improvement

Abstract: This paper presents a circuit configuration to reduce the harmonic contents at the AC mains of a 12-pulse zigzag configured autotransformer based DBR. The proposed circuit configuration employs a tapped interphase bridge rectifier at the DC side of 12-pulse DBR that results in higher pulses in the supply current. Thus, reducing the harmonic content and thereby improving the power quality of the system. Since the autotransformer employed is zigzag configured, the need for ZSBT is eliminated. Moreover, the proposed circuit configuration at the DC side shapes the supply current near to a sine wave. Further, the proposed configuration is analyzed, simulated in MATLAB Simulink and the simulation results are presented, which confirms the improvement in power quality parameters in the input AC line current. Further, the viability of the proposed configuration is verified by experimental results which confirm the suitability of the proposed configuration in AC-DC applications.

Comparison of sine-wave frequency estimation methods in respect of speed and accuracy for a few observed cycles distorted by noise and harmonics

Abstract: The paper deals with frequency estimation methods of sine-wave signals for a few signal cycles and consists of two parts. The first part contains a short overview where analytical error formulae for a signal distorted by noise and harmonics are presented. These formulae are compared with other accurate equations presented previously by the authors which are even more accurate below one cycle in the measurement window. The second part contains a comparison of eight estimation methods (ESPRIT, TLS, Prony LS, a newly developed IpDFT method and four other 3-point IpDFT methods) in respect of calculation time and accuracy for an ideal sine-wave signal, signal distorted by AWGN noise and a signal distorted by harmonics. The number of signal cycles is limited from 0.1 to 3 or 5. The results enable to select the most accurate/ fastest estimation method in various measurement conditions. Parametric methods are more accurate but also much slower than IpDFT methods (up to 3000 times for the number of samples equal to 5000). The presented method is more accurate than other IpDFT methods and much faster than parametric methods, which makes it possible to use it as an alternative, especially in real-time applications.

Highly Efficient Waveform Acquisition Condition in Equivalent-Time Sampling System

Abstract: This paper describes the optimal waveform acquisition condition between the measured waveform repetitive frequency (fsig) and the sampling clock frequency (fCLK) in an equivalent-time sampling system, when the measured waveform is periodic. We have obtained that in the case of fCLK / fsig = 1.6180.. or the golden ratio, a waveform missing phenomenon for the equivalent-time sampling can be avoided and highly efficient waveform acquisition sampling can be realized. We consider that this can be explained using the relationship to the golden section search algorithm. This paper presents its theoretical consideration and simulation results, and we consider that these results can be utilized in several LSI testing applications such as an ADC histogram testing method using a sine wave input and a timing measurement circuit design besides the equivalent-time sampling system.

Experimental and Computational Studies on the Basic Transmission Properties of Electromagnetic Waves in Softmaterial Waveguides

Abstract: Conventional waveguides are usually made of metallic materials, and they are effective pathways for the transmission of electromagnetic waves. A “Softmaterial waveguide”, by contrast, is supposed to be made of dielectric material and ionic fluids. In this work, by means of both experiment and computational simulation we examined one kind of softmaterial waveguide, which has the configuration of ionic fluids filled in and out of a dielectric tube. We investigated configurations with varied parameters, i.e., tube thickness from 0.2 mm to 5.0 mm, tube length of 2.0–12.0 cm, ionic concentration covering 4 orders of magnitude from 0.0002–2.0 mol/L, frequency of 10 Hz to 100 MHz for sine wave excitations, pulse duration of 5 ns to 100 ms for excitation pulses. We also mimicked the myelin sheath structure in myelinated axons in simulation. Both experimental and simulation results consistently showed a clear confinement effect for the energy flux of transmitting electromagnetic waves inside the dielectric tube, strongly supporting the model of softmaterail waveguide. The results revealed that the softmaterial waveguide had a low-pass nature, where the intensity of transmitted signals saturated at a duration of 10–100 μs for pulses, or cut off at frequency of 10–100 kHz for sine waves. And, the transmission efficiency increased with the thickness of the dielectric layer, as well as ion concentration of the solution. The results may help for a better understanding various electrical communication behaviors observed in biosystems, where a natural lipid membrane with bilateral fluids was suggested as the efficient pathway for pulsed neural impulses in a way similar to soliton-like electromagnetic pulses transmitting in a softmaterial waveguide.

Performance of Inductive Wireless Power Transfer Between Using Pure Sine Wave and Square Wave Inverters

Abstract: Convenient inductive wireless power transfer (WPT) transmits the electric power via a magnetic wave in a resonance condition. Generally, not only high frequency square wave (SQW) inverter but also modified sine wave and pure sine wave (PSW) inverters are used in the WPT systems. However, using the SQW inverter for the WPT system could be a simpler method, with lower switching loss, and an inverter with fewer components. This article presents the comparison between using the PSW and the SQW inverters via the same H-bridge inverter kits in an inductive WPT system. The results show that the SQW inverter efficiency was higher than the PSW inverter. Also, the input current, including the output voltage and current of the WPT system of the two inverters were not significantly different. In addition, the inverters losses were lower than the WPT system losses. Moreover, the efficiency of the WPT system using the SQW inverter was not significantly different from the use of the PSW inverter.

Space Vector Modulation Topology for Two Level Three Phase Voltage Source Inverter

Abstract: Modulation topology of space vector is a modern vector look towards pulse width modulation for two level inverter. It is advanced method for obtaining sine wave with reduced total harmonic distortion (THD). This method is increasing rapidly in recent year because it is easier to implement this method and it requires less computational time for calculation. In this paper, general purpose three phase two level space vector voltage source inverter (VSI) has been analyzed which is widely used for medium voltage application. The outcome of three phase two level VSI has been demonstrated by using MATLAB / SIMULINK result and total harmonic distortion is evaluated through FFT analysis.

Partial sine wave tracking dual mode control topology for a single-phase transformerless photovoltaic system

Abstract: A unique high efficiency photovoltaic (PV) system is presented. It uses partial sine wave tracking for a pulse-width modulation (PWM) boost converter as well as a full-bridge inverter. The boost converter and full-bridge inverter are connected via a compact intermediate film capacitor (i.e. non-smoothing DC link stage). PWM switching is activated by a dual mode control technique. In the proposed topology, simultaneous switching of both power conversion stages is avoided and therefore this increases the power conversion efficiency. The distinctive operating principles of these two power processing stages are discussed and analyzed with the experimental results for single-phase loading of the PV system.

PGC demodulation real-time normalization correction device and method in sinusoidal phase modulation interferometer

Abstract: The invention discloses a PGC demodulation real-time normalization correction device and method in a sinusoidal phase modulation interferometer. An optical path structure containing a measurement interferometer and a monitoring interferometer is constructed, an electro-optic phase modulator is placed in a public reference arm of the two interferometers, and high-frequency sine wave modulation andlow-frequency triangular wave modulation are applied at the same time; sinusoidal modulation is used to generate phase carriers, and PGC demodulation is carried out to obtain orthogonal signals containing to-be-measured phase information; the triangular wave modulation enables the orthogonal signals to change periodically, a Lissajous figure corresponding to the orthogonal signals is subjected toellipse fitting, and real-time normalization correction on the PGC demodulation orthogonal signals is realized; and measured displacement is calculated through calculating the phase difference variation between the two paths of interference signals, and nanoscale displacement measurement is realized. Nonlinear errors caused by changes of a phase modulation depth, phase delay, multiplier and filtergains and the like in PGC demodulation are eliminated, sub-nanometer measurement precision can be achieved, and the device and the method disclosed in the invention are applicable to precision displacement measurement in the high-end equipment manufacturing and processing field.

Probability of the Pure Sine Wave in the Power Quality Issues

Abstract: The paper pinpoints that the pure sine wave in the power distribution animates in the text book of the power system. On the examination, contaminated sine wave is found ubiquitously in the power devices of the industrial, commercial and domestic consumers load touched by the pitiable power quality and uncertainty of the distribution. The generating and distribution agencies vend the electricity to consumers to care for power quality issues besides on the root of the norms imposed by the electricity act. Addressing the significant needs, the challenges and issues are to be adopted in the power grids as global standards in the green environment.