Frequency Sine Wave Research Articles

Control of high-voltage pump motor using a frequency sine-wave filter converter

The method of control of a pump motor using a frequency converter as the most promising for saving energy in pumping units is described in the article. The installation of a two-transformer circuit with a low-voltage frequency converter at a pumping station in Krasnoyarsk with three network pumps equipped with DASO4-450X high-voltage asynchronous electric motors with a power of 630 kW and a voltage of 6 kV was also tested. The introduction of a two-transformer circuit and a low-voltage frequency converter with the inclusion of a sinus filter reduces the energy costs by 37%, reduces the temperature of the entire pump unit to 44 ° C and reduces the number of stops by 10%. In addition, the use of a frequency converter allows to increase the reliability of the entire system, as well as to reduce the risk of a breakthrough of the pipeline network, which is achieved by automatically maintaining pressure within the specified limits.

Single-Phase Sine Wave Frequency Inverter Power Supply

Single-phase sine wave frequency inverter power supply can be used to convert Direct Current (DC) into Alternating Current (AC) in order to power up some ac device when people only have dc power. Our design is to create a device that we can change its frequency and output voltage. So we use inverter circuit to produce ac current and use Microcontroller to change its frequency. Eventually this circuit can generate 40-50Hz sin waves which can be used to replace ac power in some situation.

Accuracy of DTFT-based Sine-wave Amplitude Estimators

In this paper the accuracies of the sine-wave amplitude estimators provided by three state-of-the-art Discrete Time Fourier Transform (DTFT)-based algorithms are compared each other when a small number of cycles is acquired and the input signal is affected by wide-band noise. These algorithms allow to reduce the detrimental contribution of the spectral image component by processing specific Discrete Fourier Transform (DFT) samples using frequency-domain interpolation and the least-squares method. Two algorithms are based on two- and three-point Interpolated DFT (IpDFT) procedure, respectively. The third algorithm applies the least-squares approach to three DTFT samples in order to reduce also the contribution of wide-band noise. The robustness of the related amplitude estimators to sine-wave frequency uncertainty and wide-band noise is also investigated.

Vortex-Driven Rotation for Three-Dimensional Imaging Under Microscopy

The noninvasive rotary motion of bio-objects for three-dimensional (3-D) observation and posture adjustment has been a great challenge in microrobotics. This letter reports a harmless noncontact 360° rotation method with a controllable velocity, which applied the vortex induced by vibrating the micropipette in an open fluidic environment. The micropipette was driven by a piezo actuator, which was mounted on a copper pillar. By generating a resonance between the copper pillar and the piezo actuator fed with sine wave of a specific frequency, we controlled the micropipette to vibrate circularly. The vibration-induced vortex around the micropipette could trap micro objects close to it, and then drive the trapped objects to rotate with the uneven drag force acting on their surface. Experiments of 360° rotation of the microbeads were carried out to demonstrate this method and analyze the rotation velocity. An application in 3-D imaging under optical inverted microscopy was achieved. The spheroids assembled by single cells were rotated, which enabled us to observe the different aspects of the cell spheroids and reconstruct its 3-D view.

Use of Sine Shaped High-Frequency Rhythmic Visual Stimuli Patterns for SSVEP Response Analysis and Fatigue Rate Evaluation in Normal Subjects.

Background: Recent EEG-SSVEP signal based BCI studies have used high frequency square pulse visual stimuli to reduce subjective fatigue. However, the effect of total harmonic distortion (THD) has not been considered. Compared to CRT and LCD monitors, LED screen displays high-frequency wave with better refresh rate. In this study, we present high frequency sine wave simple and rhythmic patterns with low THD rate by LED to analyze SSVEP responses and evaluate subjective fatigue in normal subjects.Materials and Methods: We used patterns of 3-sequence high-frequency sine waves (25, 30, and 35 Hz) to design our visual stimuli. Nine stimuli patterns, 3 simple (repetition of each of above 3 frequencies e.g., P25-25-25) and 6 rhythmic (all of the frequencies in 6 different sequences e.g., P25-30-35) were chosen. A hardware setup with low THD rate (<0.1%) was designed to present these patterns on LED. Twenty two normal subjects (aged 23–30 (25 ± 2.1) yrs) were enrolled. Visual analog scale (VAS) was used for subjective fatigue evaluation after presentation of each stimulus pattern. PSD, CCA, and LASSO methods were employed to analyze SSVEP responses. The data including SSVEP features and fatigue rate for different visual stimuli patterns were statistically evaluated.Results: All 9 visual stimuli patterns elicited SSVEP responses. Overall, obtained accuracy rates were 88.35% for PSD and > 90% for CCA and LASSO (for TWs > 1 s). High frequency rhythmic patterns group with low THD rate showed higher accuracy rate (99.24%) than simple patterns group (98.48%). Repeated measure ANOVA showed significant difference between rhythmic pattern features (P < 0.0005). Overall, there was no significant difference between the VAS of rhythmic [3.85 ± 2.13] compared to the simple patterns group [3.96 ± 2.21], (P = 0.63). Rhythmic group had lower within group VAS variation (min = P25-30-35 [2.90 ± 2.45], max = P35-25-30 [4.81 ± 2.65]) as well as least individual pattern VAS (P25-30-35).Discussion and Conclusion: Overall, rhythmic and simple pattern groups had higher and similar accuracy rates. Rhythmic stimuli patterns showed insignificantly lower fatigue rate than simple patterns. We conclude that both rhythmic and simple visual high frequency sine wave stimuli require further research for human subject SSVEP-BCI studies.

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

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.

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

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

Accurate frequency estimation of a noisy sine-wave by means of an interpolated discrete-time Fourier transform algorithm

This paper investigates the accuracy of a recently proposed sine-wave frequency estimator based on the interpolation of Discrete-Time Fourier Transform (DTFT) spectrum samples located one frequency bin apart. Specifically, an analytical expression for the variance of the Interpolated DTFT (IpDTFT) frequency estimator due to additive wide-band noise is derived in the case when the acquired sine-wave samples are weighted by a Maximum Sidelobe Decay (MSD) window. The derived expression enables the identification of an iterative algorithm, called IpDTFT-NR procedure, that ensures the maximum Noise Rejection on the IpDTFT frequency estimator. Moreover, the accuracy of the IpDTFT-NR procedure is compared with that of another algorithm, called IpDTFT-IR procedure, which ensures the maximum Image component interference Rejection on the IpDTFT frequency estimator. To this aim, accurate expressions for the Mean Square Errors (MSEs) of the two frequency estimators are derived. Also, the value of the Signal-to-Noise Ratio (SNR) up to which the IpDTFT-NR procedure outperforms the IpDTFT-IR one is determined as a function of the number of analysed sine-wave cycles. Once the SNR and the number of observed cycles of the analysed signal are known or estimated, the knowledge of this threshold enables the definition of an algorithm, called IpDTFT-IR/NR procedure, that estimates the sine-wave frequency by using the most accurate of the two procedures above. The accuracies of the IpDTFT-IR/NR procedure and of other state-of-the-art interpolated Fourier algorithms are compared with each other using both simulation and experimental data.

PID controller design to generate pulsatile flow rate for in vitro experimental studies of physiological flows.

Producing accurate pulsatile flow rates is essential for many in vitro experimental studies in biofluid dynamics research. A controller system was developed to control a flow loop to produce easily adjustable pulsatile flow rates with sufficient accuracy. An Arduino board is used as a micro-controller to control a pump to produce various pulsatile flow rates, and an open-source proportional-integral-derivative (PID) control algorithm is developed for this purpose. Four non-trivial pulsatile waveforms were produced by the PID controller, as well as an iterative controller, and the performance of both controllers was evaluated. Both the PID and iterative controllers were able to successfully produce slowly-varying signals (single and multi-harmonic low frequency sine waves), but for high frequency signals where the flow has strong acceleration/deceleration (e.g. for physiological waveforms) the iterative controller exhibited significant undershoot. The comparison of PID and iterative controllers suggests that if the desired flow rate is a low frequency, simple waveform then the iterative controller is preferred due to simplicity of implementation. However, if the desired signal is rapidly changing and more complicated then the PID controller achieves better results. This system can be implemented in many flow loops due to its simplicity and low cost, and does not require a mathematical model of the system.

On the propagation of a low frequency excitation in a perturbed FitzHugh–Nagumo system: Simulation and experiments

In this paper, we first report the response of an elementary FitzHugh–Nagumo electronic circuit excited by a low frequency sine wave and perturbed by an additive high frequency deterministic perturbation. This preliminary study constitutes a reference to analyze the collective behavior of a chain of 45 coupled elementary cells. In particular, we focus on the propagation of a low frequency sine wave which is only applied on the first fifteen cells of the lattice. It is shown that a high frequency sine wave which perturbs the whole network can enable or disable the propagation of this low frequency signal. By reducing the strength of the intercellular coupling below a critical value, we also establish that the propagation fails whatever the amplitude of the perturbation. Finally, by adding a stochastic perturbation to the high frequency deterministic perturbation, we numerically and experimentally investigate their combined effects on the propagation of the low frequency component. Numerical and experimental results reveal that, under certain conditions, noise can assist the propagation of the low frequency excitation.

Effect of noise and harmonics on sine-wave frequency estimation by interpolated DFT algorithms based on few observed cycles

In this paper the performances of two state-of-the-art Interpolated Discrete Fourier Transform (IpDFT) algorithms are analyzed when sine-wave frequency must be estimated over short observation intervals. The first estimator, called enhanced IpDFT (e-IpDFT) algorithm, exploits a two-point interpolation and compensates the detrimental contribution of the fundamental image component on the estimated frequency by using an iterative procedure. The second estimator, called IpDFT-EIF algorithm, eliminates that contribution by using a three-point interpolation. Both algorithms reduce the spectral leakage due to time-domain truncation by weighting the acquired signal by a Maximum Sidelobe Decay (MSD) window. The analysis is performed in the case of ideal, noisy, and noisy and harmonically distorted sine-waves. Theoretical expressions for the estimation Mean Square Errors (MSEs) due to noise and harmonics are derived and verified through simulations and experiments. The performed analysis allows the selection of the best frequency estimator for given signal-to-noise-ratio, harmonic content, and number of acquired cycles.

Modulation-format-free and automatic bias control for optical IQ modulators based on dither-correlation detection.

A novel automatic bias control (ABC) method for optical in-phase and quadrature (IQ) modulator is proposed and experimentally demonstrated. In the proposed method, two different low frequency sine wave dither signals are generated and added on to the I/Q bias signal respectively. Instead of power monitoring of the harmonics of the dither signal, dither-correlation detection is proposed and used to adjust the bias voltages of the optical IQ modulator. By this way, not only frequency spectral analysis isn't required but also the directional bias adjustment could be realized, resulting in the decrease of algorithm complexity and the growth of convergence rate of ABC algorithm. The results show that the sensitivity of the proposed ABC method outperforms that of the traditional dither frequency monitoring method. Moreover, the proposed ABC method is proved to be modulation-format-free, and the transmission penalty caused by this method for both 10 Gb/s optical QPSK and 17.9 Gb/s optical 16QAM-OFDM signal transmission are negligible in our experiment.

A Novel Sensorless Initial Rotor Position Estimation Method for Permanent Magnet Synchronous Motors

&lt;span style="color: black; font-family: 'Times New Roman','serif'; font-size: 9pt; mso-fareast-font-family: 新細明體; mso-fareast-theme-font: minor-fareast; mso-ansi-language: EN-US; mso-fareast-language: EN-US; mso-bidi-language: AR-SA; mso-bidi-font-style: italic;" lang="EN-US"&gt;This paper presents a high efficiency initial rotor position estimation method for Permanent Magnet Synchronous Motors (PMSM). The approach uses the viable inductance model to analyze the optimal motor injection sine wave frequency as the motor’s test signal. Unlike other high-frequency injection methods, this approach does not require trial and error experiments. The injection frequency is identified by programmable simulations using Matlab. Experimental evaluation of 3-phase PMSM showed that this injection frequency optimization method works successfully. The proposed method can find the optimal injection frequency without experimentation, and outperforms other test signals in terms of accuracy, vibration quantity and noise. This microprocessor-developed 3-phase PMSM control driver can be applied to electrical appliances, machine tools and automation.&lt;/span&gt;

An Experimental Investigation of Cutting Temperature and Tool Wear in 2 Dimensional Ultrasonic Vibrations Assisted Micro-Milling

Two dimensional Ultrasonic vibration assisted milling (2D UVAM) well knows process that involved in high tech system to generate ultra range of frequency applied to the milling process. More industries nowadays become aware taking this opportunity to improve their productivity without decreasing their product accuracies. This paper investigate a comparative machining between UVAM and conventional machining (CM) in tool wear and cutting temperature in milling process. Micro amplitude and sine wave frequency will be generate into the workpiece jig by piezo-actuator. Thus, creating a micro gap that allow heat remove effectively with the chip produces. A more complex tool trajectory mechanics of 2D UVAM has been found during this research. The approaching the tool tip into the workpiece surfaces is affected by the amplitude displacement along the frequency applied. It is found that the tool wear was reduce and surface roughness improvement by applying the 2D UVAM compared to the CM when choosing the optimum amplitude and appropriate frequency.

The Effect of Distributed Parameters on Conducted EMI from DC-Fed Motor Drive Systems in Electric Vehicles

The large dv/dt and di/dt outputs of power devices in DC-fed motor drive systems in electric vehicles (EVs) always introduce conducted electromagnetic interference (EMI) emissions and may lead to motor drive system energy transmission losses. The effect of distributed parameters on conducted EMI from the DC-fed high voltage motor drive systems in EVs is studied. A complete test for conducted EMI from the direct current fed(DC-fed) alternating current (AC) motor drive system in an electric vehicle (EV) under load conditions is set up to measure the conducted EMI of high voltage DC cables and the EMI noise peaks due to resonances in a frequency range of 150 kHz–108 MHz. The distributed parameters of the motor can induce bearing currents under low frequency sine wave operation. However the impedance of the distributed parameters of the motor is very high at resonance frequencies of 500 kHz and 30 MHz, and the effect of the bearing current can be ignored, so the research mainly focuses on the distributed parameters in inverters and cables at 500 kHz and 30 MHz, not the effect of distributed parameters of the motor on resonances. The corresponding equivalent circuits for differential mode (DM) and common mode (CM) EMI at resonance frequencies of 500 kHz and 30 MHz are established to determine the EMI propagation paths and analyze the effect of distributed parameters on conducted EMI. The dominant distributed parameters of elements responsible for the appearing resonances at 500 kHz and 30 MHz are determined. The effect of the dominant distributed parameters on conducted EMI are presented and verified by simulation and experiment. The conduced voltage at frequencies from 150 kHz to 108 MHz can be mitigated to below the limit level-3 of CISPR25 by changing the dominant distributed parameters.

Determination of nanosecond pulse parameters on transfer function measurement for power transformer winding deformation

Transfer function method is now a widely acceptable tool to diagnose transformer winding deformations. A sweep frequency sine wave generator is often used to excite the different modes of resonance and anti-resonances. However, it is time consuming. Nanosecond square wave pulse signal offers an alternative that can serve the same objective. However, as so far, there is no certain criterion for selecting pulse parameters. This paper provides a comprehensive method for the determination of nanosecond square wave pulse parameters for transfer function evaluation of power transformer for winding deformation studies.

AC electrothermal actuation mechanism for on-chip mixing of high ionic strength fluids

The ability to maintain a relative low temperature rise, portability and also achieve fast mixing process is major advantage for high ionic strength processing, where high conductive fluids handled by AC electrothermal (ACET) effects. In this study we examine the frequency dependency of AC electroosmotic (ACEO) and ACET effects, to generate high efficient temperature gradients and corresponding conductivity/permittivity gradients with relatively low temperature rise. We drive the electrodes by amplitude-modulated (AM) sine-wave and it generates non-uniform electric field with small temperature rise, in comparison with the simple sine-wave. The excitation parameters such as voltage amplitude A, sine-wave frequency fc, and also modulation frequency fm, were optimized to achieving both high mixing efficiency and low temperature rise. Technological details of proposed silicon/PDMS fabrication method has been discussed in details for the AC Electrothermally-driven micromixer and a set of numerical simulations were done for the microactuator. An effective ACET flow along with the low temperature rise is observed in optimal frequency range of 0.1 MHz < fc < 9 MHz. A full mixing efficiency achieved by using only three pairs of the electrodes and with the maximum temperature rise of 5.5 K. The reduction in temperature rise is very important for extending ACET mixing applications and device portability. As a proof of chaotic regime, two particles released inside the channel and particle tracing accomplished, the results showed that the particles were stretched and folded. The technological details of fabrication process and thermal effects handling has been discussed in details.

Importance of Contrast Sensitivity to High and Low Spatial Frequency and Artificial Neural Networks for Visual Impairment in Multiple Sclerosis

This research compared contrast sensitivity (CS) to high and low spatial frequency of angular frequency stimuli and sine-wave gratings, respectively, to assess adults diagnosed with multiple sclerosis (MS), MS with optic neuritis (ON) (MSON) and control. We also investigated whether the involved cognitive impairments affect CS, and whether the technique of artificial neural network (ANN), coupled with the CS to only two spatial frequencies, correctly predict MS. The present cross-sectional study measured CS of adults MS, MSON and control, 22-50 years-old, that used a psychophysical procedure designed with the forced-choice method. The t test for independent samples showed that the CS was better in the control, followed by MS and MSON. The MSON group had lower CS values at all tested angular frequency stimuli and low sine-wave gratings as well (p<0.0001). The frequency 24 cycles/360° and 4.0 cpd were the ones that best differentiated the groups surveyed. The neuropsychological test stroop was the only one to yield a difference between groups (p<0.0001). There was no correlation between the psychophysical measures and the protocols of optical coherence tomography. These data suggest that visual impairments found in MS and MSON are related to CS. The ANN 44221 architecture was successful in separating people with MS from controls, by using the spatial frequencies of 24 cycles/360o and 4.0 cpd that showed good correlation performance (0.71) in the test phase. Research employing this perspective will proceed with the main purpose of verifying the extent to which the use of CS for sine-wave gratings and angular frequency stimuli are relevant in the early assessment of MS.

풀 디지털 High Frequency 정현파 전원장치 개발

본 논문은 의료기기용 고주파 수술기 및 RF 통신장치 등에 사용되는 high frequency 정현파 전원장치의 디지털화에 관한 연구로 고주파 수술기의 경우 절개의 깊이를 사용자가 임의로 설정할 수 있고, 동작 모드에 따라 절개와 응고를 한 장치로 시술하는 것이 가능하여 그 사용이 증가 추세에 있으나 기존의 고주파 수술기의 경우 핵심 부품이 전량 수입에 의존해야 하는 진공관으로 구성되어 있어 회로의 구성과 유지보수의 측면에서 어려움이 있으며 핵심 부품을 전량 수입하여야 함에 따라 단가의 상승을 피할 수 없어 디지털화 한 대체 기술의 개발 필요성이 매우 크다 할 수 있다. 따라서 본 연구에서는 기존의 고주파 수술기에 사용되는 high frequency 정현파 전원장치를 디지털화한 전원장치를 제안하고 실험을 통해 그 성능을 입증 하였다. In this paper, we deals with the digitization of high frequency sine wave power supply using power source of high frequency surgical equipment and RF device. High frequency surgical equipment has been using commonly on medical surgery because of its merits such as programmable depth of incision, availability of incision and coagulation in the same device, increasing the usability on surgical side. However, the core part of the device is consists of vacuum tubes which are expensive, not ease to use and must be imported, therefore it is inevitable of high prices, forces to develop the fully digitized alternative technology. The fully digitized high frequency sine wave power supply for surgical device is proposed and verified by experimental results.

Experimental Study on Influence of Hardening of Isolator in Multiple Isolation Building

An innovative multiple isolation building system is proposed and the influence of hardening in seismic isolators on the response of a multiple isolation building is investigated by shaking table vibration tests for a scaled structural model. From the observation in recent earthquake disasters in far-fault ground motions, e.g. the 2011 off the Pacific coast of Tohoku earthquake, a significant concern is reminded that the long-period and long-duration ground excitation may cause severe damages to the existing base-isolated buildings. In order to enhance the seismic vibration suppression performance of those buildings, the multiple isolation structure has been developed recently as one of the innovative solutions. The multiple isolation structure is defined as a seismic isolated building which has multiple isolation stories by inserting supplemental isolators in the middle story in addition to the base. In this paper, the advantages of the proposed multiple isolation system subjected to an extremely strong far-field earthquake ground motion as the worst scenario are studied by the vibration test for a scaled model. In the scaled model, a non-linear restoring-force characteristic (hardening) is provided by the geometrical non-linearity which can be realized by inserting linear springs in the direction perpendicular to the vibration direction. The influence of this hardening property on the structural responses is studied by comparing with the responses of the same model without hardening effect. In the comparison with the base-isolated building, the fundamental seismic vibration suppression performances are evaluated in terms of the transfer functions of both a multiple isolation system and a base isolation system to the base input by sweeping frequencies of stationary sine waves using a controllable compact shaking table. In the numerical simulations, the effect of the friction in the isolation layers is also investigated.