Showing papers on "Sine wave published in 2007"

System and method for generating radio frequency energy

Abstract: An electrosurgical generator is disclosed. The electrosurgical generator includes a power supply for generating a DC voltage. The electrosurgical generator also includes a first parallel inductor-capacitor circuit being driven by a first signal at a first predetermined frequency and a second parallel inductor-capacitor inductor-capacitor circuit driven by a second signal at the first predetermined frequency phase shifted 180°. The electrosurgical generator further includes a series inductor-capacitor resonant circuit operably connected in series with a primary winding of a transformer. The first and second parallel inductor-capacitor circuits are operably connected to the transformer, such that the first inductor-capacitor circuit generates a positive half sine wave and the second inductor-capacitor circuit generates a 180° phase-shifted positive half sine wave to generate a full sine wave in a secondary winding of the transformer.

Modulation-Based Harmonic Elimination

Abstract: A modulation-based method for generating pulse waveforms with selective harmonic elimination is proposed. Harmonic elimination, traditionally digital, is shown to be achievable by comparison of a sine wave with modified triangle carrier. The method can be used to calculate easily and quickly the desired waveform without solution of coupled transcendental equations

Effects of discharge area and surface conductivity on partial discharge behavior in voids under square voltages

Abstract: The transitions of partial discharge (PD) behavior with aging in a void under ac voltages with sine wave and square wave were observed. The transition of the PD magnitude with aging under square wave showed the same tendency as that under sine wave. Moreover, the experimental results also showed some distinctive characteristics of PDs under square voltage (e.g. more than two pulses after the voltage rise time and their transition with aging). These phenomena were explained in terms of the effect of discharge area and the change in surface condition due to PD degradation

Neural Network Based Method for Predicting Nonlinear Load Harmonics

Abstract: Generation of harmonics and the existence of waveform pollution in power system networks are important problems facing the power utilities. The increased use of nonlinear devices in industry has resulted in direct increase of harmonic distortion in the industrial power system in recent years. Interaction between loads and sources in a power distribution network is a complex process and often not possible to explain analytically without making assumptions. The determination of true harmonic current distortion of a load is further complicated by the fact that the supply voltage waveform at the point of common coupling (PCC) is rarely a pure sinusoid. This paper proposes a neural network based method to find a way of distinguishing between load contributed harmonics and supply harmonics, without disconnecting any load from the network. A neural network structure with memory is used to model the admittance of the nonlinear load. Once training is achieved, the neural network predicts the true harmonic current of the load if it could be supplied with a clean sine wave. The main advantage of this method is that only waveforms of voltages and currents have to be measured and is applicable for single phase as well as multiphase loads. This could be integrated into a commercially available power quality instrument or be fabricated as a standalone instrument that could be installed in substations of large customer loads, or used as a hand-held clip on instrument

Power factor correction boost converter with continuous, discontinuous, or critical mode selection

Abstract: In a method and apparatus for controlling power factor correction in mixed operation modes, a frequency of the input voltage is obtained by detecting the zero crossing points of the input voltage. A peak of the input voltage is obtained by detecting input voltage with 90 degree phase. Thus, the present invention predicts the input voltage by its frequency and peak and the characteristic of the sine wave. A digital signal processor computes the duty and frequency of a boost switch, switching the operation mode of the boost converter among continuous mode, critical mode and discontinuous mode according to input voltage or the load. According to another aspect, the operation is switched to critical mode from the average current mode when a zero current is detected before the charging and recharging cycle of the boost switch is finished. Overcurrent protection may be achieved by controlling current in response to detected voltage to provide a substantially constant power level. The overcurrent protection may be adaptive in nature.

A 12-Pulse AC–DC Rectifier With High-Quality Input/Output Waveforms

Abstract: This paper describes an ac-dc rectifier, which draws sinusoidal current waveforms from the utility. Also, it can supply either a ripple-free current or voltage to the dc load by using a dc filter. The technology involves an accurate shaping of the dc current by using two forced-commutated switches (IGBTs). The shaping of the dc current is reflected back into the shaping of the input currents, which become pure sine waves. The resulting system is reliable and able to handle rapid load variations with a simple and robust control system. It also operates under rectification and inversion. Detailed analysis and a complete set of experimental results from a 380-V 20-kVA rectifier system are provided.

Precision Measurements Using a 300 mV Josephson Arbitrary Waveform Synthesizer

Abstract: We have developed a Josephson digital-to-analog converter, otherwise know as a Josephson arbitrary waveform synthesizer, with 300 mV peak output voltage. This is the first system of its kind with demonstrated quantum accuracy. We show precision synthesized waveforms from dc to 100 kHz with measured distortion and harmonic content below 115 dBc (dB below the carrier or fundamental). The heart of the system is a superconducting microwave integrated circuit with two Josephson junction arrays biased in parallel for the microwave drive and connected in series to double the voltage for the audio frequency output waveforms. New superconducting integrated circuits with twice as many stacked junctions and improved microwave circuits have allowed us to more than double the output voltage of our recent system. We also demonstrate that quantum-based synthesized arbitrary waveforms (not just sine waves) can be used for precision measurements of a high-performance commercial analog-to-digital converter.

Liquid and moisture sensing by ultra-wideband pseudo-noise sequence signals

Abstract: The use of ultra-wideband signals for moisture sensing by electromagnetic wave interaction provides more information on the material under test compared to single tone or narrowband approaches, regarding spatial and frequency dependent phenomena. Current activities to regulate the emission of electromagnetic waves in the spectral band up to 10 GHz for sensor applications open new perspectives for microwave moisture sensing. Therefore, improved and cost effective ultra-wideband measurement principles will become more and more interesting. The use of short pulses or swept sine waves are classic approaches to cover a large spectral band. However, this paper deals with some variants of an alternative method, which applies pseudo-random codes, namely M-sequences, to stimulate the test objects. The method permits monolithic integration of the RF-electronics in SiGe technology. The signal generation and data capturing are referred to a common stable single tone clock and they are controlled by steep trigger signals. This provides for very stable operation, which allows for measurements in both time and frequency domain. Two versions of an M-sequence approach will be considered and their functioning will be demonstrated by means of simple measurement examples.

Dynamic Phasor Measurement Unit Test System

Abstract: This paper presents the plans and progress towards the development of a dynamic phasor measurement unit (PMU) performance test system at NIST. We describe an algorithm for taking time-synchronized samples of single-phase voltage and current power signals and calculating their dynamic parameters, in particular the signal magnitude, phase, frequency, and rate of change of frequency that a PMU reports. PMUs must time stamp their values at periodic Coordinated Universal Time (UTC) markers called the update times. Thus, to provide a reference for PMU testing the sampled data can be fit to a model to define the value of a dynamic parameter at a specific time. The analysis model proposed in this paper assumes that the dynamic magnitude and frequency parameters of the signals are constant over the sampling interval analyzed. This analysis interval is usually the same as the update period or an integer multiple of that period. In the proposed analysis model the dynamic magnitude and frequency parameters are considered a polynomial in time about the update times. The order of the polynomial can be adjusted in a way that meets the needs of the signal being analyzed, yet minimizes the computational effort and sensitivity to noise. We show that when the dynamic variations are analyzed in this way, a single matrix can be used to iteratively converge on a good estimate of the dynamic frequency and magnitude parameters. The polynomial model can be used to generate and analyze test signals. Several test patterns are proposed, which include linearly changing magnitudes or frequencies. As expected, during low voltage tests of the system, the analysis does very well when the generation model matches the analysis model. Several other generation models are also proposed, such as sine waves or damped sine waves. The proposed analysis model is shown to be very accurate in these cases as well.

Time-Interleaved Digital-to-Analog Converters for UWB Signal Generation

Abstract: In this paper, a differentially encoded time-interleaved digital-to-analog converter (TIDAC) structure for ultra-wideband (UWB) signal generation is presented. We show that the output spectrum of the TIDAC is identical to the output of a DAC running at a higher sampling rate. To support the mathematical derivations, the UWB signal generator has been implemented on FPGA hardware and measurements have been taken for a sinusoidal wave, a Gaussian UWB pulse shape and for a UWB OFDM signal. The measurements show that, compared to the single-channel DAC, the mirror images around the sampling frequency can be reduced by about 30 dB and the analog interpolation filter design is simplified.

Nonlinear motor control techniques

Abstract: The present invention provides a torque loop control method for servomotors utilizing discontinuous pulse width modulation that incorporates measuring the power factor in real time. Also included is a sine wave generator for software-based spectrum analysis.

Numerical Study of Interrupted Impinging Jets for Cooling of Electronics

Abstract: The objective of this paper is to present the results of a numerical investigation of the effect of flow pulsations on local, time-averaged Nusselt number of an impinging air jet. The problem was considered to provide inputs to augmenting heat transfer from electronic components. The solution is sought through the FLUENT (Version 6.0) platform. The standard k-epsiv model for turbulence equations and two-layer zonal model in wall function are used in the problem. Pressure-velocity coupling is handled using the SIMPLEC algorithm. The model is first validated against some experimental results available in the literature. A parametric study is carried out to quantify the effect of the pulsating jets. The parameters considered are (1) average jet Reynolds number (5130 < Re < 8560), (2) sine and square wave pulsations, (3) frequencies of pulsations (25 < / <400 Hz), and (4) height of impingement to jet diameter ratios (5 < H/d < 9). In the case of sine wave pulsations, the ratio of root mean square value of the amplitude to the average value (AN) was varied from 18% to 53%. The studies are restricted to a constant wall heat flux condition. Parametric conditions for which enhancement in the time-averaged heat transfer from the surface can be expected are identified.

Least Squares Multiharmonic Fitting: Convergence Improvements

Abstract: The robustness of least squares (LS) algorithms combined with the increased processing capabilities of DSPs will enable the development of a new brand of low-cost flexible instrumentation based on LS methods. Sine-fitting algorithms estimate the sine wave parameters of a digitized signal by minimizing the LS error. They can be used in a large number of important applications such as characterization of analog-to-digital converters, measurement of impedances, and test of the frequency response of linear systems. For signals with harmonics, multiharmonic fitting algorithms estimate the harmonic amplitudes and phases. In this paper, the convergence of the LS multiharmonic fitting algorithm is analyzed. Improvements are presented to increase convergence and minimize the number of iterations.

Uniform Asymptotics Applied to Ultrawideband Pulse Propagation

Abstract: A canonical problem of central importance in the theory of ultrawideband pulse propagation through temporally dispersive, absorptive materials is the propagation of a Heaviside step-function signal through a medium that exhibits anomalous dispersion. This problem is rich in the use of asymptotic theory. Sommerfeld and Brillouin provided the first (qualitatively accurate but quantitatively inaccurate) closed-form approximations of the dynamic evolution of this waveform through a single-resonance Lorentz model dielectric based upon Debye's method of steepest descent. An improved approximation has since been provided by Oughstun and Sherman using modern, uniform asymptotic methods that rely upon the saddle-point method. An accurate, uniform asymptotic approximation describing the dynamical evolution of the unit step-function modulated sine wave signal through a single-resonance Lorentz model dielectric is presented here based upon their work. This refined asymptotic description results in a continuous evolution of the propagated field for all space-time points.

Strip theory for underwater vehicles in water of finite depth

Abstract: This paper addresses the need to know the unsteady forces and moments on an underwater vehicle in finite-depth water, at small enough submergences for it to be influenced by sea waves. The forces are those due to the waves themselves, as well as the radiation forces due to unsteady vehicle motions. Knowledge of these forces and the mass distribution of the vehicle allow solution of the equations of motion at a single-frequency. Since the theory is linear, any incident wave field can be decomposed into the sum of many individual single-frequency sinusoidal waves. The motions due to each frequency component can then be added together to obtain the total predicted vehicle motions. The wave forces are due to the undisturbed sea wave plus those due to the diffracted wave necessary to satisfy boundary conditions on the vehicle. The long-used strip theory for ships, with the inviscid-flow approximation, is modified for finite depth and inclusion of lift forces on the vehicle fins. The two-dimensional solutions for the forces on each strip are found by a different method than is commonly used for strip theory. This form of the theory is easier to deal with and requires much less computing time than a fully three-dimensional approach. Experiments are conducted and their results are compared with the theory. Excellent agreement is found between the theoretical and experimental wave forces, including the diffracted wave. It is shown that inclusion of the forces on the fins not only improves the theoretical wave forces, but also brings the results of theory for the radiation forces and moments due to vehicle motions much closer to the experimental values that the theory without inclusion of fin lift forces.

Dromion soliton waves and the their evolution in the background of Jacobi sine waves

Abstract: By an improved mapping approach, Bcklund transformation approach and a variable separation approach, a series of excitations of the (2+1)-dimensional generalized Breor-Kaup (GBK) system is derived. Based on the derived excitations, we find some complex waves of GBK equation. Then we discussed the evolution of dromion solitions in the background of the Jacobi sine waves.

Method for driving alternate current of light emitting diode and operating voltage thereof

Abstract: A method for driving AC of light emitting diodes includes an AC obtaining measure for obtaining an AC sine wave signal having positive and negative half-cycle waveforms; a power modulation measure for modulating the AC sine wave signal and an impedance of first and second LED groups according to at least two opposite conducting directions connected in parallel to change the positive half-cycle waveform to comply with an operation range of the positive half-cycle driving signal of the first LED group and modulate the negative half-cycle waveform to comply with an operation range of the negative half-cycle driving signal of the second LED group; and a power driving measure for driving the first and second LED groups by the positive and negative half-cycle driving signals, and the first and second LED groups are driven sequentially according to the operating cycles of the positive and negative half-cycle driving signals respectively.

Closed-Loop Control of a Complementary Clamp Piezoworm Actuator

Abstract: The concept of the complementary clamp piezoworm actuator with a diode-shunted delay circuit was experimentally verified through prototype testing. One clamp uses high voltage to grip and low voltage to release while the other clamp operates in reverse fashion. The resulting piezoworm actuator can be driven by a two-channel controller with the two clamps sharing the first channel and the extender piezoelectric stack using the second channel. The piezoworm achieved a speed of 440 mum/s and had a force capacity of 12.5 N when driven in open loop with trapezoidal waveforms. A delay circuit improved the force capacity from 12.5 to 14.7 N using a resistance of 1000 Omega. A closed-loop tracking controller was developed for the prototype. It is shown that the prototype closed-loop system has a repeatability less than plusmn20 nm for a 100 mum step input and can track a 100 mum, 0.05 Hz sine wave with a 1% peak error and less than a 200 nm average error.

Radar signal design using chaotic signals

Abstract: The use of chaotic signals in radar imaging applications present particular advantages as they behave like pseudo noise, have a wide band, and are easy to generate. A chaotic frequency modulated (FM) sine wave is an example of a chaotic signal that can yield higher transmitted mean power when peak-power limited transmitters are used. Unlike the random FM signal, the behavior of chaotic FM signals is not fully understood. In this paper, two approaches for analyzing the spectrum of chaotic FM signals are discussed. The first approach approximates the chaotic signal with noise and the second one, deals with the condition for the chaotic signal to remain chaotic after frequency modulation and consequently have a wide band spectrum.

High precise control method for a new type of piezoelectric electro-hydraulic servo valve

Abstract: A new type of piezoelectric electro-hydraulic servo valve system was proposed. And then multilayer piezoelectric actuator based on new piezoelectric ceramic material was used as the electricity-machine converter of the proposed piezoelectric electro-hydraulic servo valve. The proposed piezoelectric electro-hydraulic servo valve has ascendant performance compared with conventional ones. But the system is of high nonlinearity and uncertainty, it cannot achieve favorable control performance by conventional control method. To develop an efficient way to control piezoelectric electro-hydraulic servo valve system, a high-precise fuzzy control method with hysteresis nonlinear model in feedforward loop was proposed. The control method is separated into two parts: a feedforward loop with Preisach hysteresis nonlinear model and a feedback loop with high-precise fuzzy control. Experimental results show that the hysteresis loop and the maximum output hysteresis by the PID control method are 4.22% and 2.11 μm, respectively; the hysteresis loop and the maximum output hysteresis by the proposed control method respectively are 0.74% and 0.37 μm, respectively; the maximum tracking error by the PID control method for sine wave reference signal is about 5.02%, the maximum tracking error by the proposed control method for sine wave reference signal is about 0.85%.

High-speed single-photon detector in telecommunication wavelength band

Abstract: In order to operate a single photon detector in communication wavelength band at a high speed, a DC bias voltage 2 lower than the breakdown voltage is applied to an InGaAs/InP avalanche photodiode (APD) 1. A 500 MHz sine wave gating signal 3 is superimposed with the DC bias voltage 2 and applied to the APD so as to exceed the breakdown voltage by about 4V in a fractional time of each period. The sine wave gating signal 3 passed through the APD 1 is substantially completely removed by a filter 4, thereby improving S/N and enabling to detect a single photon even if the avalanche multiplication time is shortened to reduce the after pulse and the detection period. As a result, it achieves to detect a single photon in the 1550 nm communication band at a high speed.

A 0.6GHz to 2GHz Digital PLL with Wide Tracking Range

Abstract: A digital PLL employing an adaptive tracking technique and a novel frequency acquisition scheme achieves a wide tracking range and fast frequency acquisition. The test chip fabricated in a 0.13 mum CMOS process operates from 0.6 GHz to 2 GHz and achieves better than plusmn3200 ppm frequency tracking range when the reference clock is modulated with a 1 MHz sine wave.

Grid sensor for the two-dimensional measurement of different components in the cross section of a multiphase flow

Abstract: Disclosed is an arrangement for quickly measuring the phase distribution or the component distribution in a flow cross section for substance mixtures also of a non-conducting type by measuring the complex electrical admittance. Said arrangement essentially features the following: at least one sine wave generator (5) which is mounted upstream from the transmitter electrodes (3a) of the excitation level and applies an alternating voltage to the transmitter electrodes (3a); current-to-voltage converters (7) which are mounted downstream from the receiver electrodes (3b), amplify the alternating current that flows from at least one excitation electrode (3a) through the medium to the receiver electrodes (3b), and convert said alternating current into a voltage signal; filter groups (10, 11, 16) and vector voltmeters (8) which are mounted downstream from the current-to-voltage converters (7) and allow the complex signal ratio Ua/Ue to be metrologically detected.

Detection of signals containing sine-wave components through measurement of the power spectral density (PSD) and cyclic spectrum

Abstract: A Wireless Regional Area Network (WRAN) receiver comprises a transceiver for communicating with a wireless network over one of a number of channels, and a signal detector for use in forming a supported channel list comprising those ones of the number of channels upon which an Advanced Television Systems Committee (ATSC) DTV (digital television) broadcast signal was not detected. The signal detector performs spectrum sensing as a function of power spectral density (PSD) and cyclic spectrum.

Optical communication wavelength band high speed single photon detector

Abstract: In order to operate a single photon detector in communication wavelength band at a high speed, a DC bias voltage 2 lower than the breakdown voltage is applied to an InGaAs/InP avalanche photodiode (APD) 1. A 500MHz sine wave gating signal 3 is superimposed with the DC bias voltage 2 and applied to the APD 1 so as to exceed the breakdown voltage by about 4V in a fractional time of each period. The sine wave gating signal 3 passed through the APD 1 is substantially completely removed by a filter 4, thereby improving S/N and enabling to detect a single photon even if the avalanche multiplication time is shortened to reduce the after pulse and the detection period. As a result, it achieves to detect a single photon in the 1550nm communication band at a high speed.

Efficient Pulse Shaping and Robust Data Transmission Using Wavelets

Abstract: Recent work has shown that the use of wavelets in a data transmission chain brings several advantages. Thus, the wavelet mothers and the associated scale functions can generate orthogonal basis that obey Nyquist's first criterion and these basis can be used as pulse shaping waveforms instead of raised cosine filters. Furthermore, robust multicarrier data transmission can be performed using wavelet carriers instead of the classical sine waves proposed by OFDM. By associating these benefits, the road towards new powerful transmission techniques in data transmission systems is widely opened.

Signals in bioimpedance measurement: different waveforms for different tasks

Abstract: Alternatives to the traditional sine wave excitation are studied in the paper. Impedance measurements can be performed much faster by using a broad bandwidth signal for excitation. Using of square wave pulses, Gaussian function and its derivative, also modifications of sinc and chirp signals, is analysed. Carefully designed pulse wave excitation can become to an alternative to established excitation waveforms, especially, when fast measurements with exact timing are required, and when the energy consumption is important.

New frequency/voltage converters for ac-electrogravimetric measurements based on fast quartz crystal microbalance

Abstract: A better understanding of the mechanisms located at the solid/electrolyte interface is becoming essential to the development of new applications in the electrochemical fields. The fast quartz crystal microbalance is an attractive and powerful gravimetric sensor which can be used in the dynamic regime to determine a mass/potential transfer function. The principle is equivalent to classical electrochemical impedance measurements; the only difference is the determination of mass changes given by the quartz crystal microbalance rather than current changes following sine wave modulations of the applied potential. This function appears very well adapted to characterize ionic exchanges at the electrochemical interface. Frequency/voltage converters are the key devices in translating the microbalance frequency response in terms of a continuous voltage change. The latter allows the transfer function to be obtained via a frequency response analyzer. Different converters were tested in this work in order to improve the performances of the experimental setup.