Showing papers on "Sine wave published in 2020"
10 Jul 2020
Abstract: In this article, a nonlocal thermoelastic model that illustrates the vibrations of nanobeams is introduced. Based on the nonlocal elasticity theory proposed by Eringen and generalized thermoelasticity, the equations that govern the nonlocal nanobeams are derived. The structure of the nanobeam is under a harmonic external force and temperature change in the form of rectified sine wave heating. The nonlocal model includes the nonlocal parameter (length-scale) that can have the effect of the small-scale. Utilizing the technique of Laplace transform, the analytical expressions for the studied fields are reached. The effects of angular frequency and nonlocal parameters, as well as the external excitation on the response of the nanobeam are carefully examined. It is found that length-scale and external force have significant effects on the variation of the distributions of the physical variables. Some of the obtained numerical results are compared with the known literature, in which they are well proven. It is hoped that the obtained results will be valuable in micro/nano electro-mechanical systems, especially in the manufacture and design of actuators and electro-elastic sensors.
82 citations
TL;DR: In this article, the deformation ratio and critical field strength of the square, sinusoidal, and triangular waveforms were compared for electrocoalescence in water-in-oil emulsions.
28 citations
TL;DR: An induction hysteresigraph using 50 Hz sine wave fields of 7 kOe maximum amplitude, generated by a solenoid-type multilayer coil, suitable for small amounts (down to tens of milligram) of magnetic materials is proposed.
Abstract: An induction hysteresigraph using 50 Hz sine wave fields of 7 kOe maximum amplitude, generated by a solenoid-type multilayer coil, suitable for small amounts (down to tens of milligram) of magnetic materials is proposed. The changes in field and magnetization are detected by a field sensing coil and a compensated pick-up coil system , respectively, the as-induced signals being processed by two analog measuring channels ( channel H and channel M ), whose output signals reproduce the time evolution H(t) and M(t) of the two quantities. These signals are recorded via PC-assisted analog-to-digital conversion and then subjected to final numerical correction and calibration; apart from the demagnetizing field correction, the possible errors caused by the stray flux generated by the magnetized sample itself are also taken into account. In addition, instead of weak signals denoising via standard filtering or smoothing algorithms, reconstruction based on flexible combinations of transition-type fitting functions of time periodic argument is proposed. To prevent signal waveform distortions that can be caused by the frequency-dependent response of channel M , a thorough analysis is carried out in the time domain, by simulating the run of a 100 kHz bandwidth severe test signal, across the stages of this channel. This signal consists of sharp ac pulses, built as a digital replica of the electromotive force induced in a pick-up coil containing the sample, during its evolution along a steep-sided hysteresis loop; an original method, using a small number of parameters, is proposed to build the spectral expansion of the test signal.
27 citations
TL;DR: The use of sine wave burst represents a feasible option for the treatment of cancer by ECT and the dependence of the frequency of the applied sine waves on the treatment efficacy is studied.
Abstract: Objective: The purpose of this work is to assess the ability of sine waves to perform electrochemotherapy (ECT) and to study the dependence of the frequency of the applied sine wave on the treatment efficacy. Methods: A subcutaneous tumor model in mice was used, and the electric field was delivered in combination with bleomycin. Sinusoidal electric fields of different frequencies, amplitudes, and durations were compared to square waves. Computer simulations were additionally performed. Results: The results confirmed the ability of a sinusoidal electric field to obtain successful ECT responses. A strong dependence on frequency was obtained. The efficacy of the treatment decreased when the frequency of the sine waves was increased. At low sinusoidal frequency, the efficacy of the treatment is very similar to that obtained with a square wave. The collateral effects such as skin burns and muscle contractions decreased for the highest frequency assayed. Conclusion: The use of sine wave burst represents a feasible option for the treatment of cancer by ECT. Significance: These results could have important implications for the treatment of cancer in the clinical world where ECT is performed with dc square pulses.
23 citations
TL;DR: In this article, an undamped method with variable delay time is proposed to solve the electrical resonance issue caused by the LC filter and stator inductor, which is suitable for resonance suppression at a variable switching frequency.
Abstract: Applying high-frequency power devices, such as gallium nitride (GaN) semiconductor devices, to the motor drive can significantly reduce system volume, losses, audible noise, and increase system power density. In this article, an LC filter designed as a sine wave filter is introduced into the servo drive system based on the GaN power device. An undamped method with variable delay time is proposed to solve the electrical resonance issue caused by the LC filter and stator inductor. Detailed stability analysis is conducted, and rules on parameter tuning are provided. With additional proper time delay, the system can be stable without any extra sensors or power losses. Besides, this method is suitable for resonance suppression at a variable switching frequency. Moreover, a wait-free and phase-continuous spread spectrum frequency modulation is applied to solve the issue of electromagnetic interference (EMI). The field-programmable gate array is used to achieve high control bandwidth when implementing the control algorithm. Finally, the ideal sinusoidal drive and low conducted EMI of a permanent magnet synchronous motor is realized. Experiments on a 100 kHz GaN inverter with the LC filter verify the validity of the proposed design and method.
23 citations
TL;DR: A modular design approach based on DSP Builder was employed to develop a quadrature vector type lock-in amplifier with automatic frequency tracking and the proposed DLIA has higher precision and efficient noise immunity.
Abstract: Aiming to overcome the problem of the frequency error between the reference signal and the measured signal in an analog lock-in amplifier, this paper presented a digital lock-in amplifier (DLIA) with accurate frequency automatic tracking to improve its performance. In this paper, a modular design approach based on DSP Builder was employed to develop a quadrature vector type lock-in amplifier with automatic frequency tracking. A reference signal generator with high-frequency resolution and a digital filter with good performance were implemented. The performance of the design was tested by determining the linearity, the Q value, and the noise immunity of the DLIA. The experimental results showed that the proposed DLIA has good linearity and the Q value can reach up to 82. The relative errors of the signals with amplitudes greater than 10 mV were less than 1% when the equivalent input was a sine wave signal with a frequency of 1 kHz and an amplitude of 500 mV. When the superimposed noise was less than or equal to 400 mV, the relative error was less than 2% in the same condition. The proposed DLIA has higher precision and efficient noise immunity.
20 citations
TL;DR: A silicon electron pump operating at the temperature of liquid helium has demonstrated repeatable operation with sub-ppm accuracy as mentioned in this paper, and the pump current, approximately 168 pA, is measured by three laboratories, and the measurements agree with the expected current ef within the uncertainties which range from 0.2 ppm to 1.3 ppm.
Abstract: A silicon electron pump operating at the temperature of liquid helium has demonstrated repeatable operation with sub-ppm accuracy. The pump current, approximately 168 pA, is measured by three laboratories, and the measurements agree with the expected current ef within the uncertainties which range from 0.2 ppm to 1.3 ppm. All the measurements are carried out in zero applied magnetic field, and the pump drive signal is a sine wave. The combination of simple operating conditions with high accuracy demonstrates the possibility that an electron pump can operate as a current standard in a National Measurement Institute. We also discuss other practical aspects of using the electron pump as a current standard, such as testing its robustness to changes in the control parameters, and using a rapid tuning procedure to locate the optimal operation point.
20 citations
19 Jul 2020
TL;DR: The potential of neuromorphic nanowire networks as a physical reservoir is demonstrated by performing benchmark reservoir computing tasks that include sine wave nonlinear transformation, sineWave auto– generation and forecasting the Mackey–Glass chaotic time series.
Abstract: We present simulations based on a model of self– assembled nanowire networks with memristive junctions and neural network–like topology. We analyze the dynamical voltage distribution in response to an applied bias and explain the network conductance fluctuations observed in our previous experimental studies. We then demonstrate the potential of neuromorphic nanowire networks as a physical reservoir by performing benchmark reservoir computing tasks. The tasks include sine wave nonlinear transformation, sine wave auto– generation and forecasting the Mackey–Glass chaotic time series.
18 citations
TL;DR: A new technique for generation of ultra-wide and flattened optical frequency comb (OFC) based on serial cascading of a phase modulator and dual-driven Lithium-Niobate Mach Zehnder modulator (DD-LiNbO3-MZM) is proposed.
Abstract: In this paper, a new technique for generation of ultra-wide and flattened optical frequency comb (OFC) based on serial cascading of a phase modulator and dual-driven Lithium-Niobate Mach Zehnder modulator (DD-LiNbO3-MZM) is proposed. Over 60 carriers were generated by carefully adjusting the RF switching voltage (RFSV) of the DD-LiNbO3-MZM and the signal frequency of the sinusoidal wave (RF) source. A low power amplified RF source with a signal driving power of 16.9dBm is applied, and the power of CW laser is kept at 3dBm. The frequency spacing (FS) is kept at 20GHz for generating the maximum number of carriers. Nonetheless, the scheme is also tested for the FSs of 64GHz, and 32GHz. Each scenario is examined in simulation environment and the main outcomes are highlighted. The proposed scheme is comparatively simple and the FS varies with the applied RF source on the modulators. The achieved OFC lines have a tone-to-noise ratio (TNR) of over 45dB with an undesired side mode suppression ratio of approximately 20dB. The comb lines are almost flat with a varying power deviation of around 0dB-6dB which is optimized to nearly 0.12dB. Furthermore, the impact of the RFSV on the generated number of carriers is studied in detail. The scheme is analyzed in terms of cost efficiency, power deviations, TNR, optical signal to noise ratio, and number of achieved comb lines.
17 citations
TL;DR: In this article, a model for absorber effective properties is developed and compared with experimental data, which is used to derive simple formulae for low frequency airborne sound absorption in linear and nonlinear regimes.
16 citations
TL;DR: Experimental results show that the proposed method can extract detail- Preserved pulse waves from facial videos under realistic situations and outperforms state-of-the-art methods in terms of detail-preserving and real time heart rate estimation.
Abstract: With the popularity of smart phones, non-contact video-based vital sign monitoring using a camera has gained increased attention over recent years. Especially, imaging photoplethysmography (IPPG), a technique for extracting pulse waves from videos, conduces to monitor physiological information on a daily basis, including heart rate, respiration rate, blood oxygen saturation, and so on. The main challenge for accurate pulse wave extraction from facial videos is that the facial color intensity change due to cardiovascular activities is subtle and is often badly disturbed by noise, such as illumination variation, facial expression changes, and head movements. Even a tiny interference could bring a big obstacle for pulse wave extraction and reduce the accuracy of the calculated vital signs. In recent years, many novel approaches have been proposed to eliminate noise such as filter banks, adaptive filters, Distance-PPG, and machine learning, but these methods mainly focus on heart rate detection and neglect the retention of useful details of pulse wave. For example, the pulse wave extracted by the filter bank method has no dicrotic wave and approaching sine wave, but dicrotic waves are essential for calculating vital signs like blood viscosity and blood pressure. Therefore, a new framework is proposed to achieve accurate pulse wave extraction that contains mainly two steps: 1) preprocessing procedure to remove baseline offset and high frequency random noise; and 2) a self-adaptive singular spectrum analysis algorithm to obtain cyclical components and remove aperiodic irregular noise. Experimental results show that the proposed method can extract detail-preserved pulse waves from facial videos under realistic situations and outperforms state-of-the-art methods in terms of detail-preserving and real time heart rate estimation. Furthermore, the pulse wave extracted by our approach enabled the non-contact estimation of atrial fibrillation, heart rate variability, blood pressure, as well as other physiological indices that require standard pulse wave.
TL;DR: In this article, a sequential conjugate gradient method is presented to reconstruct the undetermined surface heat flux for nonlinear inverse heat conduction problem (IHCP), which combines the merits of sequential function specification method (SFSM) and convolutional gradient method (CGM).
TL;DR: In this article, a method for the accurate experimental characterization and fully automated extraction of compact nonlinear models for field effect transistors (FETs) is proposed, which leads to a charge-conservative description, based on a single large-signal measurement under a two-tone sinusoidal wave excitation.
Abstract: A new method is proposed for the accurate experimental characterization and fully automated extraction of compact nonlinear models for field-effect transistors (FETs). The approach, which leads to a charge-conservative description, is based on a single large-signal measurement under a two-tone sinusoidal wave excitation. A suitable choice of tone frequencies, amplitudes, and bias allows to adequately characterize the transistor over the whole safe operating region. The voltage-controlled nonlinear functions describing the two-port FET model can be computed over an arbitrarily dense voltage domain by solving an overdetermined system of linear equations. These equations are expressed in terms of a new nonlinear function sampling operator based on a biperiodic Fourier series description of the acquired frequency spectra. The experimental validation is carried out on a 0.25- $\mu \text{m}$ gallium nitride (GaN) on silicon carbide (SiC) high-electron-mobility transistor (HEMT) under continuous-wave (CW) and two-tone excitation (intermodulation distortion test).
TL;DR: In this article, a joint experimental and theoretical study is made of instability mechanisms of locally confined internal gravity wave beams in a stratified fluid. And experimental evidence is presented that transverse beam variations induce a horizontal mean flow of the streaming type and greatly subdue the instability.
Abstract: A joint experimental and theoretical study is made of instability mechanisms of locally confined internal gravity wave beams in a stratified fluid. Using as forcing a horizontal cylinder that is oscillated harmonically in the direction of beam propagation makes it possible to generate coherent finite-amplitude internal wave beams whose spatial profile comprises no more than a single wavelength. For forcing amplitude above a certain threshold depending on the driving frequency, such thin wave beams are observed to undergo an instability that involves two subharmonic perturbations with wavepacket-like spatial structure. Although it bears resemblance to the triadic resonant instability (TRI) of small-amplitude sinusoidal waves, the present instability cannot be predicted by TRI theory as the primary wave is not nearly monochromatic, but instead contains broadband wavenumber spectrum. In contrast, the experimental observations are in good agreement with the predictions of a formal linear stability analysis based on Floquet theory. Finally, experimental evidence is presented that transverse beam variations induce a horizontal mean flow of the streaming type and greatly subdue the instability.
TL;DR: In this article, the performance of a submerged cylindrical point absorbing wave energy converter was explored under the addition of different nonlinear stiffness (bistable) conditions, and a three-degree-of-freedom submerged point absorber with bistability subjected to regular and irregular waves.
TL;DR: A new smoothness indicator on four-point stencil is constructed which will reduce to the underlying linear scheme for monochromatic waves, and behaves the same as the underlyinglinear scheme for approximate dispersion relation (ADR).
TL;DR: In this article, the wave localization in continuous elastic bodies and a regular lattice is studied, and the wave amplitudes and the energy fluxes in the wave amplitude and energy flux are analyzed.
Abstract: We consider a body, homogeneous or periodic, equipped with a structure composed of dynamic inhomogeneities uniformly distributed along a line, and study free and forced sinusoidal waves (Floquet - Bloch waves for the discrete system) in such a system. With no assumption concerning the wave nature, we show that if the structure reduces the phase velocity, the wave localizes exponentially at the structure line, and the latter can expand the transmission range in the region of long waves. Based on a general solution presented in terms of non-specified Green’s functions, we consider the wave localization in some continuous elastic bodies and a regular lattice. We determine the localization-related frequency ranges and the localization degree in dependence on the frequency. While 2D-models are considered throughout the text, the axisymmetric localization phenomenon in the 3D-space is also mentioned. The dynamic field created in such a structured system by an external harmonic force is obtained consisting of three different parts: the localized wave, a diverging wave, and non-spreading oscillations. Expressions for the wave amplitudes and the energy fluxes in the waves are presented.
TL;DR: An Improved Sinusoidal Pulse Width Modulation (ISPWM) technique carried out to obtain pure sine waves for voltage and current signals in Quasi Z-Sourc Inverters (QZSIs) in the load side is given in this study.
Abstract: An Improved Sinusoidal Pulse Width Modulation (ISPWM) technique carried out to obtain pure sine waves for voltage and current signals in Quasi Z-Sourc Inverters (QZSIs) in the load side is given in this study. This switching method can be examined to two and multi-phase approaches simply through the addition of the same controller structure to per phase. This is the main advantage of the proposed converter to obtain higher voltage gains at the output ends of this inverter. The idea is to generate a positive rectified voltage at the output point of the QZSI and positive and negative rectified voltages at the output terminals of the QZSI in two-phase approaches to improve the quality of the output voltage of the F-Bridge Inverter (FBI). These rectified voltages are applied to the Full-Bridge Inverter (FBI) block and pure sine waves to obtain the load current and voltages. 1.34% of the Total Harmonic Distortion (THD) for the output voltage has been reported in the one-phase system while 0.88% of THD has been obtained in the two-phase approach. Besides, the reliability of the QZSI was tested through the Mean Time to Failure (MTTF) analysis with the values of the proposed components. The calculations show a very good result for the long-life of the converter. All experimental and simulations steps have been obtained for the same values of the components to support and confirm the accuracy and correctness of the proposed IMSPW. For the states of single-phase and two-phase converters, a 50 Hz sine-wave with 220 V and 440 V peak to peak amplitude has been acquired. Evaluations of the quality of the voltage and current waveforms related to different active (Resistive, P) and reactive (combination of Resistance and Inductance, QL) loads have been carried out. Experimental results show confirmation for all simulation and mathematical results.
TL;DR: In this paper, the authors analyzed the mechanism of cavitation jet occurrence by combining the jet shape, the striking force, and the cavity pressure, and showed that a long enough peak bandwidth has an essential effect on the striking work operation.
Abstract: Periodical dynamic characteristics induced by geometric parameters and operational variables of the self-excited pulsed cavitation jet under the optimum experimental condition is analyzed in the present study. The mechanism of cavitation jet occurrence is interpreted by combining the jet shape, the striking force, and the cavity pressure. With the increase of the inlet pressure, the pulsed frequency increases, and the amplitude decreases. Besides, the pulsed frequency decreases, and the amplitude increases as the oscillation chamber length gets much longer. It reflects that the shape and trend of the waveform are different under different structural parameters and the same operating pressure, while the waveform is the same with the same nozzle structure parameters and the various operating pressures. The peak bandwidth of the waveform is reduced with the increase of the pressure. A long enough peak bandwidth has an essential effect on the striking work operation. Only the peak value of the strike force is kept for an extended period so that it can get an effective strike. The waveform of all dynamic characteristics in the pulsed jet is harmonic. These harmonic waves can be seen as the superposition of several sine waves or cosine waves. It is required that the dominant frequency of pressure oscillation waves is single to avoid the negative influence of noise waves, and then a better effect of striking force is obtained.
TL;DR: Based on idealized sine waves, this technique modifies peak-to-peak results to find arrival times using the output frequency of the received signal, which significantly reduces subjectivity and produces improved reliability in estimating specific arrival times without the need of any frequency sweeps as mentioned in this paper.
Abstract: Determining the small strain stiffness Gmax of soils in a laboratory is generally achieved using bender elements. Shear wave propagation is affected by the soil medium and boundary conditions causing distortion in output signals, which introduces error in travel time estimates. This study proposes a novel technique for determining first arrival time in a systematic manner. Based on idealized sine waves, this technique modifies peak-to-peak results to find arrival times using the output frequency of the received signal. By incorporating the initial half wavelength of received signals, five methods depending on the length of the signal chosen for calculating the output frequency are proposed in this article. The applicability of the proposed technique is evaluated based on signals reported in published literature and obtained for Singapore marine clay (uncemented and lightly cemented). For most soil types and testing conditions, it was demonstrated that the proposed technique produces close estimates with reported original arrival times. On the contrary, other techniques, such as peak-to-peak, cross-correlation, and cross spectrum, often underestimated the shear wave velocities when the output signals contained relatively low frequency contents. Consequently, the proposed technique significantly reduces subjectivity and produces improved reliability in estimating specific arrival times without the need of any frequency sweeps. Moreover, by incorporating the quality and shape of signals into the analysis, better estimates of first arrival can be established, especially for noisy signals or signals affected by near-field effects.
TL;DR: In this paper, a flat-bottomed hole (FBH) defect is modeled by finite element method in a polymethylmethacrylate (PMMA) structure and the desired information from this defect is retrieved by its local defect resonance (LDR) frequency which is estimated through a Principal Component Analysis (PCA).
19 Mar 2020
TL;DR: The paper aims at designing the advanced simulation model that is able to generate samples similar to human respiration signals typically acquired by a Doppler or Continuous-wave step frequency short-range radar system based on the continuous non-linear transformation of a sine wave with amplitude and frequency modulation and a colored Gaussian noise.
Abstract: The paper aims at designing the advanced simulation model that is able to generate samples similar to human respiration signals typically acquired by a Doppler or Continuous-wave step frequency short-range radar system. The model is based on the continuous non-linear transformation of the mixture of a sine wave with amplitude and frequency modulation and a colored Gaussian noise. Despite not being based on a detailed physiological description of the respiration process, the proposed model can produce samples of respiration signals resembling the signals acquired by a radar with high accuracy. In contrast to the widely-used monoharmonic model, the model does not exhibit strict periodicity that allows researchers to consider it to be an appropriate sample generator for thorough testing procedures performed over existing algorithms of respiration signal detection as well as newly-created ones.
TL;DR: In this paper, a low-frequency piezoelectric motor driven by a 50 Hz sine wave was proposed to simplify the driving power of the inertia drive PPI.
Abstract: The inertia drive piezoelectric motor generally employs an asymmetric waveform driving signal, and the power supply for generating such type of driving signal is complicated and costly. In order to simplify the driving power of the inertia drive piezoelectric motor, a low-frequency piezoelectric motor driven by a 50 Hz sine wave is proposed in this paper. We first analyze the working principle: the pressure between the rotor and the stator changes asymmetrically in one working cycle, driving the rotor’s one-way rotation. Then we establish the dynamic model of the system and study the influence of the pre-stress between the stator and the rotor on the output performance of the low-frequency piezoelectric motor. Finally, the prototype is made and tested for performance. Experiments show that the low-frequency piezoelectric motor resonates at a driving frequency of 50 Hz, where the amplitudes of the stator in the vertical direction and the rotational direction are 21 μm and 136 μm respectively. When the pre-stress between the stator and the rotor is 5 N, the motor speed reaches a maximum value of 4.3 r/min; when the pre-stress is 11 N, the torque of the motor reaches a maximum value of 0.29 Nm.
TL;DR: A method for signal processing that covers two main steps related to R/D decomposition and including signal segmentation to neglect AM/FM modulations, iterative sine wave fitting using the least square method, signal filtering technique by subtraction fitted sine from the raw signal, and impulse segmentation and description are proposed.
Abstract: Condition monitoring is a well-established field of research; however, for industrial applications, one may find some challenges. They are mostly related to complex design, a specific process performed by the machine, time-varying load/speed conditions, and the presence of non-Gaussian noise. A procedure for vibration analysis from the sieving screen used in the raw material industry is proposed in the paper. It is more for pre-processing than the damage detection procedure. The idea presented here is related to identification and extraction of two main types of components: (i) deterministic (D)—related to the unbalanced shaft(s) and (ii) high amplitude, impulsive component randomly (R) appeared in the vibration due to pieces of ore falling down of moving along the deck. If we could identify these components, then we will be able to perform classical diagnostic procedures for local damage detection in rolling element bearing. As deterministic component may be AM/FM modulated and each impulse may appear with different amplitude and damping, there is a need for an automatic procedure. We propose a method for signal processing that covers two main steps: (a) related to R/D decomposition and including signal segmentation to neglect AM/FM modulations, iterative sine wave fitting using the least square method (for each segment), signal filtering technique by subtraction fitted sine from the raw signal, the definition of the criterion to stop iteration by residuals analysis, (b) impulse segmentation and description (beginning, end, max amplitude) that contains: detection of the number of impulses in a decomposed random part of the raw signal, detection of the max value of each impulse, statistical analysis (probability density function) of max value to find regime-switching), modeling of the envelope of each impulse for samples that protrude from the signal, extrapolation (forecasting) envelope shape for samples hidden in the signal. The procedure is explained using simulated and real data. Each step is very easy to implement and interpret thus the method may be used in practice in a commercial system.
TL;DR: Although reducing fAC reduces the computation time, thermal oscillations appear at points near the electrode, which suggests that a minimum value of fAC should be used.
TL;DR: In this article, a GaN-based matrix converter for variable frequency drive (VFD) is discussed, where a sine wave filter is adopted to cope with the terminal voltage quality irrespective of cable length.
Abstract: Gallium nitride (GaN) devices have been widely adopted to achieve high efficiency and high power density as alternative solutions to silicon devices. When the GaN power devices are used for variable frequency drive (VFD) systems, the high dv/dt pulses at the motor terminal, which induce shaft voltage and common mode current, should be carefully considered to ensure system reliability. Although the high dv/dt issues can be mitigated with a dv/dt filter method, it leads to performance degradation depending on cable length. Meanwhile, a matrix converter also becomes a next-generation power converter for the VFDs which has a regeneration capability and unity power factor. Thus, this paper discusses the GaN-based matrix converter for the VFD as a study case considering the motor terminal voltage quality and the common mode current. Also, a sine wave filter is adopted to cope with the terminal voltage quality irrespective of cable length. The optimized design procedure of the sine filter considers practical issues. Experimental results are presented to suggest a suitable solution for the GaN-based VFDs in accordance with the cable length.
TL;DR: In this article, a 1/70-scale pile-soil-cable-stayed bridge model with a main span of 1400m was fabricated and a finite element model was developed in OpenSees that could capture the seismic response changes caused by the traveling wave effects of specific sine waves and proximately reproduce the experimental results.
TL;DR: A novel single-supply four-switch five-level inverter topology based on the H4 two-level full bridge inverter, one coupling inductor and two diodes are added to constitute the proposed topology by means of the LPS-PWM modulation strategy with frequency doubling ability.
Abstract: This paper focuses on the problems of a large number of components and complex structure for traditional five-level inverters. In order to solve the problem, a novel single-supply four-switch five-level inverter topology is proposed. Based on the H4 two-level full bridge inverter, one coupling inductor and two diodes are added to constitute the proposed topology. By means of the LPS-PWM modulation strategy with frequency doubling ability, one pair of complementary power switches operate at power frequency, and the other pair of high-frequency switches operate at the half of the output sine wave modulation frequency, which effectively reduces the switching loss and electromagnetic interference resulting from high switching frequency. In addition, three kinds of extended circuits of four-switch five-levels are proposed. A comprehensive comparison against the state-of-the-art topologies in terms of the required number of components is performed to attest the outperforming merits of the proposed topology. Finally, various experimental results are presented to validate the feasibility and operability of the proposed topology.
16 Nov 2020
TL;DR: In this article, the effect of the square wave waveform on the magnetic abrasive finishing process was investigated, and it was shown that the magnetic cluster fluctuates faster with the size of the magnetic particles.
Abstract: The magnetic abrasive finishing (MAF) process is an ultra-precision surface finishing process. In order to further improve the finishing efficiency and surface quality, the MAF process using an alternating magnetic field was proposed in the previous research, and it was proven that the alternating magnetic field has advantages compared with the static magnetic field. In order to further develop the process, this study investigated the effect on finishing characteristics when the alternating current waveform is a square wave. The difference between the fluctuation behavior of the magnetic cluster in two alternating magnetic fields (sine wave and square wave) is observed and analyzed. Through analysis, it can be concluded that the use of a square wave can make the magnetic cluster fluctuate faster, and as the size of the magnetic particles decreases, the difference between the magnetic cluster fluctuation speed of the two waveforms is greater. The experimental results show that the surface roughness of SUS304 stainless steel plate improves from 328 nm Ra to 14 nm Ra within 40 min.
05 Nov 2020
TL;DR: In this article, a design of photovoltaic based multilevel inverter using level shift pulse width modulation strategy is presented, where two signals are used; one as a reference signal and the other carrier signal.
Abstract: In this paper, a design of photovoltaic based multilevel inverter using level shift pulse width modulation strategy is presented. Both the fundamental frequency and higher frequency switching are usedin multilevel inverter. Here, two signals are used; one as a reference signal and the other carrier signal. For the pulse width modulation method, the sinusoidal wave is used as a reference signal while the triangular wave is used as a carrier signal in multilevel level inverters (MLI. This paper will primarily discuss the effect of change in level shift of carrier signals on the hybrid PV based MLI and to count harmonics in multilevel PV based inverters, which in turn improves the voltage and minimize the losses significantly. The simulation is carried out on a multilevel cascaded hybrid PV based inverter with level shift strategy to check the voltage and current harmonics using Matlab/Simulink.