Method for eliminating second harmonic distortion based on modulation phase difference in TDLAS technology

2020 ◽  
Author(s):  
Xu Chong ◽  
Wang Songceng ◽  
Chen Hao ◽  
Wei Bin ◽  
Ju Yu ◽  
...  
Keyword(s):  
Phase Difference ◽  
Second Harmonic ◽  
Harmonic Distortion ◽  
Modulation Phase

scholarly journals Second-harmonic generation in focused beam fields of phased-array transducers in a nonlinear solid with a stress-free boundary

2019 ◽  
Vol 1 (2) ◽  
pp. 117-125
Author(s):  
Hyunjo Jeong ◽  
Shu-zeng Zhang ◽  
Xiong-bing Li
Keyword(s):  
Second Harmonic Generation ◽  
Harmonic Generation ◽  
Phase Difference ◽  
Phased Array ◽  
Second Harmonic ◽  
Free Boundaries ◽  
Harmonic Components ◽  
Focused Beams ◽  
Pulse Echo ◽  
Focused Beam

Abstract In nonlinear acoustic harmonic generation in solids with stress-free boundaries, such a boundary is known to destructively change the second harmonic generation, and the pulse-echo method is not practically applicable. Focused beams have often been used for fluid nonlinearity and biomechanical imaging in pulse-echo test setups. This paper considers the focused beam fields of linear phased-array transducers to ensure that pulse-echo harmonic generation can be applied to solids with stress-free boundaries. The fundamental and second-harmonic beam fields that are focused and reflected at the stress-free and rigid boundaries are calculated and their properties are investigated in terms of the received average fields. The phase difference between the two second-harmonic components after reflection from the boundary—that is, the reflected and the newly generated second harmonic—is emphasized. The phase difference is used to explain the improved and accumulated second harmonic observed in the simulation results.

Broadband Reduction of the Second Harmonic Distortion During Nonlinear Ultrasound Wave Propagation

2010 ◽  
Vol 36 (10) ◽  
pp. 1568-1580 ◽  
Author(s):  
Mirza Pasovic ◽  
Mike Danilouchkine ◽  
Guillaume Matte ◽  
Antonius F.W. van der Steen ◽  
Olivier Basset ◽  
...  
Keyword(s):  
Wave Propagation ◽  
Second Harmonic ◽  
Harmonic Distortion ◽  
Ultrasound Wave ◽  
Nonlinear Ultrasound

Effect of Modulation Source Properties upon Signal-To-Noise Ratios of Inelastic Electron Tunneling Spectra

1986 ◽  
Vol 40 (8) ◽  
pp. 1180-1183 ◽  
Author(s):  
F. A. Dethomas ◽  
Cecil Dybowski ◽  
Harvey S. Gold
Keyword(s):  
Electron Tunneling ◽  
Second Harmonic ◽  
Signal To Noise Ratio ◽  
Harmonic Distortion ◽  
Inelastic Electron ◽  
Signal To Noise ◽  
Noise Ratio ◽  
Inelastic Electron Tunneling ◽  
Electron Tunneling Spectroscopy ◽  
Lock In

Lock-in amplification using ac modulation and second-harmonic detection is routinely employed in such techniques as ac polarography, ac voltammetry, and inelastic electron tunneling spectroscopy (IETS). Properties of the modulation source are shown in the present IET studies to limit the obtainable signal-to-noise ratio of a spectrum. A single inelastic electron tunneling junction is used to demonstrate the effect of various commercial modulation sources on the IET spectrum of benzoic acid on alumina. With all other parameters being held constant, the signal-to-noise ratio of the IET spectrum is found to be inversely correlated with the total harmonic distortion of the modulation source.

scholarly journals ANALYSIS OF RL-CIRCUIT SUPPLIED BY VOLTAGE WITH SINUS OR SQUARE WAVEFORM

2019 ◽  
Vol 34 (3) ◽  
pp. 607-612
Author(s):  
Goce Stefanov ◽  
Vasilija Sharac
Keyword(s):  
Phase Difference ◽  
Power Factor ◽  
Electronic Circuit ◽  
Harmonic Distortion ◽  
Power Source ◽  
Point Of View ◽  
Voltage Regulators ◽  
Serial Connection ◽  
Effective Voltage ◽  
Power Point

The serial connection of resistor R and inductance L is a basic electronic circuit. It's the same is main circuit in industrial power consumers: electric motors, induction furnaces, welding devices and other electrical consumers. The ratio of the values on resistor and inductance in the serial circuit determines the amount of active energy that the power source delivers to the consumer. From the power point of view, the amount of this energy should be as high as possible, ie the circuit should work with a good power factor and a good efficiency.When the RL-circuit is supplied by sinusoidal-prostoperiodic voltage the amount of active energy is determined by the values on effective voltage and current in the circuit, and the power factor determined by the phase difference between the voltage and current. In the literature there is detail information for the work of the serial RL-circuit supplied by sinusoidal voltage.The situation is quite different when the RL-circuit is supplied by voltage with square waveform. The amount of delivered energy then depends not only on the phase difference between the voltage and the current, but also and from the harmonic distortion of the magnitudes of the voltage and current.Such RL-circuits, supply by voltage with square waveform are found in all power converters: speed regulators in directional and alternating motor, induction heating devices, voltage regulators for different RL-consumers. In the literature which deals with this matter, there is room for clarification of nature of the behavior on RL-circuit supply by voltage with square waveform.In this paper first is made a mathematical calculation of power when the serial RL-circuit is supplied by voltage with sinus waveform and when it is supplied by voltage with square waveform. Also are give the results obtained with simulations in the PowerSim software package. In finally are given the experimental results of this circuit. An analysis of the obtained results and a comparison of the performance of the RL-circuit supply by the two analyzed waveforms, sinusoidal and quadratic are made.

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