Showing papers on "Sine wave published in 2015"

Performance of Sinusoidal Scanning With MPC in AFM Imaging

Abstract: An atomic force microscope (AFM) is an extremely versatile investigative tool in the field of nanotechnology, the performance of which is significantly influenced by its conventional zig-zag raster pattern scanning method. In this paper, in order to increase its imaging speed, we consider the use of a sinusoidal scanning method, i.e., a spiral scanning method with an improved model predictive control (MPC) scheme. In this approach, spirals are generated by applying waves, each with a single frequency and slowly varying amplitude, in the X-piezo (sine wave) and Y-piezo (cosine wave) of the piezoelectric tube scanner (PTS) of the AFM. As these input signals are single frequencies, the scanning can proceed faster than traditional raster scanning, without exciting the resonant mode of the PTS. The proposed MPC controller reduces the phase error between the reference position input and measured output sinusoids and provides better tracking of the reference signal. Also, a notch filter is designed and included in the feedback loop to suppress vibrations of the PTS at the resonant frequency. The experimental results show that, using the proposed method, the AFM is able to scan a 6 μm radius image within 2.04 s with a quality better than that obtained using the conventional raster pattern scanning method.

High-Quality Sine Wave Generation Using a Differential Boost Inverter at Higher Operating Frequency

Abstract: Buck-converter-based topologies are used to generate high-frequency sinusoidal outputs. Buck-based inversion circuits such as voltage source inverters or class-D amplifiers have inherent control-to-output linearity in large-signal sense. However, in these topologies, the instantaneous output is always smaller than the dc-input during linear modulation. A differential boost inverter (DBI) is a boost-based topology that is used to generate a sinusoidal output. In DBI, the instantaneous output can be higher or lower than the dc-input voltage. DBI exhibits nonlinear control-to-output behavior in large-signal dynamic sense. Therefore, generating a high-frequency sinusoidal output using this topology is a challenge. The issues associated with a DBI for high-frequency sine wave generation are characterized in this paper. Conventional linear and nonlinear control techniques fail to produce a high-quality sine wave output at higher operating frequency. A nonlinear feedback linearization technique is proposed, which forces the output to be linear with respect to the reference even at higher operating frequency. This leads to a high-frequency high-quality sine wave generation using a DBI. The proposed modulator is verified using a laboratory prototype to generate a sine wave up to 2 kHz. A triangular wave of 100-Hz frequency is also generated by the proposed technique. Superior dynamic responses of a dynamic linearizing modulator controlled DBI for a step change in frequency, load current, input voltage, and reference are also experimentally verified.

One-Volt Josephson Arbitrary Waveform Synthesizer

Abstract: A quantum-accurate waveform with an rms output amplitude of 1 V has been synthesized for the first time. This fourfold increase in voltage over previous systems was achieved through developments and improvements in bias electronics, pulse-bias techniques, Josephson junction array circuit fabrication, and packaging. A recently described ac-coupled bipolar pulse-bias technique was used to bias a superconducting integrated circuit with 25 600 junctions, which are equally divided into four series-connected arrays, into the second quantum state. We describe these advancements and present the measured 1 V spectra for 2 Hz and 10 Hz sine waves that remained quantized over a 0.4 mA current range. We also demonstrate a 2 kHz sine wave produced with another bias technique that requires no compensation current and remains quantized at an rms voltage of 128 mV over a 1 mA current range. Increasing the clock frequency to 19 GHz also allowed us to achieve a maximum rms output voltage for a single array of 330 mV.

Linear Flux Pump Device Applied to High Temperature Superconducting (HTS) Magnets

Abstract: This paper presents a novel linear flux pump which could be used to magnetize 2G HTS tapes and coils. The design is based on an iron magnetic circuit together with copper solenoids and is powered by a current source driver circuit. Several applied waveforms were tested including a symmetric sine wave and an asymmetric trapezoidal wave. Both standing and travelling waves were applied. The measurements focused on the effects of frequency and magnitude of the applied field and their effect on the system pumping efficiency. It was found that a trapezoidal wave was more effective than a sine wave, producing a greater final current at the same applied frequency and field strength. The maximum induced current in the superconducting coil was 19 A which was achieved using an applied field of 50 mT, applied as a travelling trapezoidal wave. The driving current to the copper coils was 5 A in amplitude with a frequency of 10 Hz. It was found that when the applied field magnitude was less than 16 mT pumping did not occur. It proved possible to pump the system with a standing wave as well as a travelling wave. This effect needs to be investigated further as it is possible that the standing wave had travelling components.

Modeling the visibility of the stroboscopic effect occurring in temporally modulated light systems

Abstract: Three perception experiments were conducted to develop a measure for predicting the visibility of the stroboscopic effect occurring in temporally modulated light systems. In the first experiment, different methodologies were evaluated for their measurement error. In the second experiment, the visibilities of the stroboscopic effect for square wave and sine wave light modulations were measured and the results were found to be consistent with previous findings for flicker perception. In the third experiment, specifically crafted, complex waveforms were used to test the theory of frequency summation. Based on the results of these three experiments, a new measure for the visibility of the stroboscopic effect was developed, consisting of a summation of the energy in all frequency components, normalized for human sensitivity.

Discrimination of internal fault from magnetising inrush current in power transformers based on sine-wave least-squares curve fitting method

Abstract: This study deals with a method for discrimination between magnetising inrush and internal fault currents in three-phase transformers based on sine-wave curve fitting. A sine wave is fitted to the normalised differential current by using the least-squares technique for each phase. The difference between the normalised differential currents and the fitted signals are calculated, which are hereafter named residual signals (RSs). Maximum range of the RSs variations is utilised for the definition of a simple criterion. Based on this criterion, the discrimination is realised within less than a half cycle of power frequency. In order to eliminate the impact of the current transformer (CT) saturation on the performance of the proposed technique, the currents are compensated by a CT saturation compensation algorithm in the first step. The proposed method is evaluated and compared with some well-known methods by a large number of simulation and experimental data. Furthermore, the proposed algorithm is evaluated in the case of a transformer, which is fed through a feeder with series capacitors. The results confirm that reliability, accuracy and speed response of the proposed technique is more than the other methods.

150–850 MHz High-Linearity Sine-wave Synthesizer Architecture Based on FIR Filter Approach and SFDR Optimization

Abstract: A low distortion sinusoidal waveform synthesizer architecture is proposed. The synthesizer utilizes 50% duty cycle and differential-mode circuitry to eliminate the even order harmonics, and it also implements a 5-phase 3-amplitude harmonic cancellation technique to suppress the 3rd, 5th, 7th, and 9th order harmonics. The compact system architecture consists of a 12-phase ring oscillator, a weighted resistor summing network, and an RC output filter. Phase shifters are adopted in the ring oscillator to enable the control of an external harmonic cancellation optimization algorithm. The proposed application of the optimization algorithm compensates the errors in the circuit and further improves the linearity of the output waveforms. This synthesizer is fabricated in 180 nm standard CMOS technology, occupies a 0.08 ${\rm mm}^{2}$ silicon area and achieves the spur-free dynamic range (SFDR) of 59 to 70 dBc from 150 to 850 MHz after the optimization procedure. It can operate from a 1 to 1.8 V supply voltage and achieve a power consumption from 9.11 to 57 mW.

An Experimental and Numerical Study of Long Wave Run-Up on a Plane Beach

Abstract: This research is to facilitate the current understanding of long wave dynamics at coasts and during on-land propagation; experimental and numerical approaches are compared against existing analytical expressions for the long wave run-up. Leading depression sinusoidal waves are chosen to model these dynamics. The experimental study was conducted using a new pump-driven wave generator and the numerical experiments were carried out with a one-dimensional discontinuous Galerkin non-linear shallow water model. The numerical model is able to accurately reproduce the run-up elevation and velocities predicted by the theoretical expressions. Depending on the surf similarity of the generated waves and due to imperfections of the experimental wave generation, riding waves are observed in the experimental results. These artifacts can also be confirmed in the numerical study when the data from the physical experiments is assimilated. Qualitatively, scale effects associated with the experimental setting are discussed. Finally, shoreline velocities, run-up and run-down are determined and shown to largely agree with analytical predictions.

Sinusoidal drive system and method for phototherapy

Abstract: The LEDs in a phototherapy LED pad are controlled so that the intensity of the light varies in accordance with a sinusoidal function, thereby eliminating the harmonics that are generated when the LEDs are pulsed digitally, in accordance with a square-wave function. This is accomplished analogically by using a sinusoidal wave to control the gate of a MOSFET connected in series with the LEDs or by using a digiltal-to-analog converter to control the gate of the MOSFET with a stair step function representative of the values of a sinusoidal function at predetermined intervals. Alternatively, pulse-width modulation is used to control the gate of the MOSFET in such a way that the average current through the LEDs simulates a sinusoidal function. In additional to using a simple sine wave function, the LED current may also be controlled in accordance with "chords" containing multiple sine waves of different frequencies.

Embedded Control of n -Level DC–DC–AC Inverter

Abstract: A generalized multilevel inverter (MLI) with frontend dc-dc conversion stage followed by a synchronized H-bridge is presented. By using this configuration along with the proposed embedded control, any desired number of levels (n) in the output voltage can be produced. The dc-dc conversion stage employs an asynchronous buck converter. The duty cycle of dc-dc converter is varied in the form of m-level piecewise constant (PWC) unidirectional sine wave to produce a similar output voltage across the dc-link capacitor. The unidirectional PWC voltage is made into n-level ac voltage, where n = (2m - 1), by the synchronized H-bridge. Hence, it is named as dc-dc-ac MLI. An 8-bit Xilinx SPARTAN 3AN field programmable gate array (FPGA)-based digital controller is utilized for the simultaneous generation of high-frequency switching pulses for dc-dc converter and synchronized fundamental frequency switching pulses for H-bridge. The desired number of levels in ac output voltage and its frequency are the essential inputs to the pulse generation algorithm implemented in FPGA. The proposed MLI is simulated in MATLAB/Simulink environment; its functioning is verified with resistive (R) and resistive-inductive (R-L) loads. The hardware prototype of MLI is built in the laboratory and its performance is validated with R, R-L loads, and few home appliances.

Performance Improvements for the NIST 1 V Josephson Arbitrary Waveform Synthesizer

Abstract: The performance of the NIST Josephson arbitrary waveform synthesizer has been improved such that it generates a root-mean-square (rms) output voltage of 1 V with an operating current range greater than 2 mA. Our previous 1 V JAWS circuit achieved this same maximum voltage over a current range of 0.4 mA by operating every Josephson junction in its second quantum state. The newest circuit synthesizes 1 V waveforms with the junctions operating in the first quantum state. The voltage per array is doubled because the number of junctions in each array was doubled through the use of improved microwave circuit designs that increased the bias uniformity to the junctions. We describe the circuit improvements and device operation, and we demonstrate the system capabilities by showing measured spectra of a 1 Hz sine wave and a dual-tone waveform. With only two arrays of the new circuit, we also synthesized a 128 mV sine wave without a compensation bias signal, which is one of the bias signals required for achieving 1 V. This is the same rms output voltage achieved with the previous circuit using four arrays.

Design, Operation, and Control of S3 Inverter for Single-Phase Microgrid Applications

Abstract: A single-phase voltage source inverter with a front-end dc–dc conversion stage followed by a synchronized push–pull configuration operating at a desired fundamental frequency (FF) is presented. The duty cycle of the dc–dc conversion stage is varied in the form of a unidirectional sine wave to produce a similar output voltage across the dc-link capacitor. The unidirectional voltage is made into an alternating voltage by the synchronized push–pull configuration. This inverter employs three semiconductor switches, in which one is operating at a high frequency and the rest are operating at an FF. Hence, it is named as the S3 inverter. Furthermore, simple and cost-effective analog circuits are presented for the generation of switching pulses and the control of the amount of power fed to the grid. The hardware prototype of the S3 inverter has been built in a laboratory, and its performance during the stand-alone and grid-connected modes of operation is validated.

Stable closed-loop fiber-optic delay of arbitrary radio-frequency waveforms.

Abstract: Thermal drifts in long fiber-optic delay lines are compensated based on chromatic dispersion. An arbitrary input radio-frequency (RF) waveform and a control RF sine wave modulate two different tunable laser sources and are coupled into the fiber delay line. The RF phase of the control tone at the output of the delay line is monitored and used to adjust the wavelengths of both sources, so that the effects of thermal drifts and dispersion cancel out. The input and control waveforms are separated in the optical domain, and no restrictions are imposed on their RF spectra. A figure of merit is proposed, in terms of the fiber delay, range of temperature changes that may be compensated for, and residual delay variations. An upper bound on performance is established in terms of the specifications of the tunable lasers. The principle is used in the stable distribution of sine waves and of broadband linear frequency-modulated (LFM) waveforms, which are commonly employed in radar systems. Lastly, the method is incorporated in stable interrogation of a localized hot-spot within a high-resolution, distributed Brillouin fiber sensing setup. The results demonstrate the applicability of the proposed protocol in the processing of arbitrary waveforms, as part of larger, more complex systems.

Time-Domain Filtering of Metasurfaces.

Abstract: In general electromagnetic response of each material to a continuous wave does not vary in time domain if the frequency component remains the same. Recently, it turned out that integrating several circuit elements including schottky diodes with periodically metallised surfaces, or the so-called metasurfaces, leads to selectively absorbing specific types of waveforms or pulse widths even at the same frequency. These waveform-selective metasurfaces effectively showed different absorbing performances for different widths of pulsed sine waves by gradually varying their electromagnetic responses in time domain. Here we study time-filtering effects of such circuit-based metasurfaces illuminated by continuous sine waves. Moreover, we introduce extra circuit elements to these structures to enhance the time-domain control capability. These time-varying properties are expected to give us another degree of freedom to control electromagnetic waves and thus contribute to developing new kinds of electromagnetic applications and technologies, e.g. time-windowing wireless communications and waveform conversion.

Moving Window Filter Based Frequency-Locked Loop for Capacitance Measurement

Abstract: The proposed frequency-locked loop (FLL) utilizes the flat frequency response characteristics of the moving window filter (MWF) in closed-loop and adaptive sampling pulse adjustment for capacitance measurement An operational amplifier (op-amp) based relaxation oscillator generates a square wave whose fundamental sine wave is extracted by MWF Then, the fundamental sine wave is tracked by the FLL to estimate its frequency which is inversely proportional to the unknown capacitance The FLL employs another MWF to track the center frequency and its variation due to capacitance The MWF offers an almost flat frequency response around the center frequency in closed-loop However, the small magnitude and phase errors observed in the flat frequency response had been corrected by adjusting the sampling pulses adaptively Experimental investigation demonstrates the capabilities of the scheme for wider and accurate capacitance measurement

A Sinusoidally Driven Lorenz System and Circuit Implementation

Abstract: Another approach is developed for generating two-wing hyperchaotic attractor, four-wing chaotic attractor, and high periodic orbits such as period-14 from a sinusoidally driven based canonical Lorenz system A sinusoidal function controller is introduced into a 3D autonomous Lorenz system, so that the abovementioned various hyperchaotic attractors, chaotic attractors, and high periodic orbits can be obtained, respectively, by adjusting the frequency of the sine function In addition, an analog circuit and a digital circuit are also designed and implemented, with experimental results demonstrated Both numerical simulations and circuit implementation together show the effectiveness of the proposed systematic methodology

Sinusoidal Wave Estimation Using Photogrammetry and Short Video Sequences

Abstract: The objective of the work is to model the shape of the sinusoidal shape of regular water waves generated in a laboratory flume. The waves are traveling in time and render a smooth surface, with no white caps or foam. Two methods are proposed, treating the water as a diffuse and specular surface, respectively. In either case, the water is presumed to take the shape of a traveling sine wave, reducing the task of the 3D reconstruction to resolve the wave parameters. The first conceived method performs the modeling part purely in 3D space. Having triangulated the points in a separate phase via bundle adjustment, a sine wave is fitted into the data in a least squares manner. The second method presents a more complete approach for the entire calculation workflow beginning in the image space. The water is perceived as a specular surface, and the traveling specularities are the only observations visible to the cameras, observations that are notably single image. The depth ambiguity is removed given additional constraints encoded within the law of reflection and the modeled parametric surface. The observation and constraint equations compose a single system of equations that is solved with the method of least squares adjustment. The devised approaches are validated against the data coming from a capacitive level sensor and on physical targets floating on the surface. The outcomes agree to a high degree.

Circumpapillary course of retinal pigment epithelium can be fit to sine wave and amplitude of sine wave is significantly correlated with ovality ratio of optic disc.

Abstract: The purpose of this study was to develop a method of quantifying the degree of optic disc tilt in normal eyes. This was a prospective, observational cross sectional study of 126 right eyes of 126 healthy volunteers. The optic disc tilt was determined from the circular peripapillary optical coherence tomographic (OCT) scan images. The course of the retinal pigment epithelium (RPE) layer in the peripapillary cross sectional scan images was fit to a sine wave curve, and the amplitude of the sine curve was used to reflect the degree of the optic disc tilt in the optical axis. The repeatability of the amplitude determinations was calculated. The correlation between the amplitude and the ovality ratio of the optic disc was determined. The correlation between the amplitude and the body height was also calculated. The mean amplitudewas 36.6 ± 17.5 pixels, which was significantly and inversely correlated with the ovality ratio of the optic disc (R = -0.59, P<0.001). The intra-rater and inter-rater correlation coefficients of the amplitude were significant high (P<0.001, both). The amplitude was significantly and inversely correlated with the body height (R = -0.38, P<0.001), but not with the axial length. In conclusion, a sine wave function can be used to describe the course of the RPE in the circumpapillary OCT images. The results indicate that the amplitude of the sine wave can be used to represent the degree of optic disc tilt. Thus, the sine wave analyses can be used as a quantifiable and repeatable method to determine the optic disc tilt.

Comparative study of the sinusoidal-wave and square-wave circulating current injection methods for low-frequency operation of the modular multilevel converters

Abstract: The modular multilevel converter (MMC), eliminating the expensive and bulky multi-winding phase-shifting transformer compared with the cascaded H-bridge converter, is shown to be of great potential in the field of medium-voltage motor drive applications. However, special care needs to be taken for MMC driving motor at low speeds, since the voltage fluctuation of the submodule capacitors increases with sinking the output frequency. And this large voltage fluctuation will cause significant voltage unbalance between the submodules and distort the output waveforms. The objective of this paper is to present a comparative study of two existing voltage fluctuation suppression methods: the sinusoidal-wave injection and the square-wave injection. Specifically, comparisons are made in terms of current stress, control limitations, and dc current harmonics. Finally, a downscaled three-phase MMC prototype has been built and the two injection methods are contrasted and evaluated by experiments.

Energy extraction from a slider-crank wave energy converter under irregular wave conditions

Abstract: A slider-crank wave energy converter (WEC) is a novel energy conversion device. It converts wave energy into electricity at a relatively high efficiency, and it features a simple structure. Past analysis on this particular WEC has been done under regular sinusoidal wave conditions, and suboptimal energy could be achieved. This paper presents the analysis of the system under irregular wave conditions; a time-domain hydrodynamics model is adopted and a rule-based control methodology is introduced to better serve the irregular wave conditions. Results from the simulations show that the performance of the system under irregular wave conditions is different from that under regular sinusoidal wave conditions, but a reasonable amount of energy can still be extracted.

Critical double impulse input and bound of earthquake input energy to building structure

Abstract: A theory of earthquake input energy to building structures under single impulse is useful for disclosing the property of energy transfer function. This property shows that the area of the energy transfer function is constant irrespective of natural period and damping of building structures. However single impulse may be unrealistic from a certain viewpoint because the frequency characteristic of input cannot be expressed by this input. In order to resolve such issue, a double impulse is introduced in this paper. The frequency characteristic of the Fourier amplitude of the double impulse is found in an explicit manner and a critical excitation problem is formulated with an interval of two impulses as a variable. The solution to that critical excitation problem is derived. An upper bound of the earthquake input energy is then derived by taking full advantage of the property of the energy transfer function that the area of the energy transfer function is constant. The relation of the double impulse to the corresponding one-cycle sinusoidal wave as a representative of near-fault pulse-type waves is also investigated.

High-frequency chopper sine wave output circuit

Abstract: The utility model discloses a high-frequency chopper sine wave output circuit. The high-frequency chopper sine wave output circuit comprises two reverse blocking IGBTs arranged in parallel between a power live wire and a load; an inductor arranged between the reverse blocking IGBTs and the load; two freewheeling tubes arranged in parallel, wherein one end of each freewheeling tube is connected between a power zero wire and the load, and the other end of each freewheeling tube is connected between the reverse blocking IGBTs and the inductor; and a filtering capacitor in parallel arrangement with the freewheeling tubes, wherein one end of the filtering capacitor is connected between the power zero wire and the load, and the other end of the filtering capacitor is connected between the inductor and the load. According to the utility model, high-frequency PWM can be output, harmonic waves are reduced, the inductor volume is decreased, and the weight is reduced; and output sine waves can be well adaptive to an illumination electric appliance and has no influences on the life of the illumination electric appliance.

Chaotic Behavior in a Dynamic Love Model with Different External Forces

Abstract: In this paper, we propose a dynamic mathematical model of love involving various external forces, in order to analyze the chaotic phenomena in a love model based on Romeo and Juliet. In addition, we investigate the nonlinear phenomena in a love model with external forces using time series and phase portraits. In order to describe nonlinear phenomena precisely using time series and phase portraits, we vary the type of external force, using models such as a sine wave, chopping wave, and square wave. We also apply various different parameters in the Romeo and Juliet model to acquire chaotic dynamics.

Inverter-based stand-alone microgrid control system using pmu

Abstract: An inverter-based stand-alone microgrid control system using a PMU, in which a converter controller configured to control a converter that determines a voltage and a phase of a point where a plurality of distributed power supply devices is interconnected. The system includes a time correction unit configured to provide a time corrected on the basis of time information received from a GPS; a signal comparison/generation unit configured to compare a sine wave generated according to a voltage magnitude and a phase reference signal with a harmonic carrier signal on the basis of the time provided by the time correction unit, and generate a PWM signal; and a switch operation control unit configured to apply the PWM signal from the signal comparison/generation unit to the converter, and operate a switch.

Mass Load Distribution Dependence of Mass Sensitivity of Magnetoelastic Sensors under Different Resonance Modes.

Abstract: Magnetoelastic sensors as an important type of acoustic wave sensors have shown great promise for a variety of applications. Mass sensitivity is a key parameter to characterize its performance. In this work, the effects of mass load distribution on the mass sensitivity of a magnetoelastic sensor under different resonance modes were theoretically investigated using the modal analysis method. The results show that the mass sensitivity and “nodal point” positions are related to the point displacement, which is determined by the motion patterns. The motion patterns are affected by resonance modes and mass load distribution. Asymmetrical mass load distribution causes the motion patterns lose symmetry and leads to the shift of “nodal point”. The mass sensitivity changing with mass load distribution behaves like a sine wave with decaying amplitude and the minimum mass sensitivity appears at the first valley. This study provides certain theoretical guidance for optimizing the mass sensitivity of a magnetoelastic sensor or other acoustic wave based sensors.

Characterization and reduction of the amplitude-to-phase conversion effects in telemetry

Abstract: We are developing a telemeter based on the measurement of the phase accumulated by an RF sine wave during its propagation in air. This wave is carried by a laser beam by an intensity modulation. The main limitation of this technique lies in amplitude-to-phase conversion occurring in the detection of this modulation. Therefore, we characterize this phenomenon for a given telemetric system and discuss how to reduce its effects on the resolution and the accuracy of the distance measurement. Finally, a solution is implemented and tested outdoors in real conditions of use.