Journal articles: 'Higher order harmonics'

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Vijayalakshmi, V. J., C. S. Ravichandran, and A. Amudha. "Predetermination of Higher Order Harmonics by Dual Phase Analysis." Applied Mechanics and Materials 573 (June 2014): 13–18. http://dx.doi.org/10.4028/www.scientific.net/amm.573.13.

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Previous research was mainly concentrated on eliminating the selected lower order harmonics depending on the level of inverter which was assumed to be high. The harmonics may be present even in the higher order also. The analysis of harmonic spectrum by Finite Fourier Transform yields a very accurate result for lower order harmonics. For obtaining accurate Total Harmonic Distortion (THD) value and the harmonic spectrum, inclusion of higher order harmonics is essential. The method for accurate estimation is proposed in this paper. In normal practice, the higher order harmonics present in the output of the inverter are suppressed by using filters. In order to obtain more optimized higher order harmonics, it is necessary to obtain an accurate assessment of the higher order spectrum. The higher order spectrum is predetermined by proposed technique termed as Dual Phase Analysis (DPA) so as to obtain more optimized switching angles with the application of any Optimization Technique. This is an effective tool to analyze the various higher order components of the harmonic spectrum.

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Ozaki, T., L. Elouga Bom, and R. A. Ganeev. "Extending the capabilities of ablation harmonics to shorter wavelengths and higher intensity." Laser and Particle Beams 26, no. 2 (June 2008): 235–40. http://dx.doi.org/10.1017/s026303460800027x.

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AbstractWe study the generation of high-order harmonics from plasma plume, by using the 20 TW, 10 Hz laser of the Advanced Laser Light Source (ALLS). We perform detailed studies on enhancement of single high-order harmonics generated in laser plasma using the fundamental and second harmonic of the ALLS beam line. Quasi-monochromatic harmonics are observed for Mn, Cr, Sb, Sn, and In plasmas. We identify most of the ionic/neutral transitions responsible for the enhancement, which all have strong oscillator strengths. Intensity enhancements of the 13th, 17th, 21st, 29th, and 33rd harmonics from these targets are demonstrated using the 800 nm pump laser and varying its chirp. We also observed harmonic enhancement from some targets for 400 nm pump laser. Using Mn plume, we demonstrated the highest harmonic photon energy (52.9 eV) at which enhancement has been observed (17th order, λ = 23.5 nm).

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Yeganeh, Mohammad, and Saifollah Rasouli. "Moiré fringes of higher-order harmonics versus higher-order moiré patterns." Applied Optics 57, no. 33 (November 16, 2018): 9777. http://dx.doi.org/10.1364/ao.57.009777.

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Kuchuk, Kfir, and Uri Sivan. "Accurate, explicit formulae for higher harmonic force spectroscopy by frequency modulation-AFM." Beilstein Journal of Nanotechnology 6 (January 13, 2015): 149–56. http://dx.doi.org/10.3762/bjnano.6.14.

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The nonlinear interaction between an AFM tip and a sample gives rise to oscillations of the cantilever at integral multiples (harmonics) of the fundamental resonance frequency. The higher order harmonics have long been recognized to hold invaluable information on short range interactions but their utilization has thus far been relatively limited due to theoretical and experimental complexities. In particular, existing approximations of the interaction force in terms of higher harmonic amplitudes generally require simultaneous measurements of multiple harmonics to achieve satisfactory accuracy. In the present letter we address the mathematical challenge and derive accurate, explicit formulae for both conservative and dissipative forces in terms of an arbitrary single harmonic. Additionally, we show that in frequency modulation-AFM (FM-AFM) each harmonic carries complete information on the force, obviating the need for multi-harmonic analysis. Finally, we show that higher harmonics may indeed be used to reconstruct short range forces more accurately than the fundamental harmonic when the oscillation amplitude is small compared with the interaction range.

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Sei, Norihiro, Hiroshi Ogawa, Kawakatsu Yamada, Masaki Koike, and Hideaki Ohgaki. "Spectral modulation of higher harmonic spontaneous emission from an optical klystron." Journal of Synchrotron Radiation 21, no. 4 (May 10, 2014): 654–61. http://dx.doi.org/10.1107/s160057751400678x.

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Higher harmonics of spontaneous emission from an optical klystron have been observed. The modulation factor of the spontaneous emission spectrum for the higher harmonics can be described by considering the observation system. When the dispersive gap of the optical klystron was fixed, the microstructure interval of the spontaneous emission spectrum at a certain resonant wavelength became narrower as the order of the higher harmonic became larger. Some unique characteristics of the higher harmonics have been clarified, and these studies are likely to contribute to the development of free-electron lasers using higher harmonics of an optical klystron in the shorter-wavelengths region.

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Giesecke, A. L., C. Peth, T. Toncian, O. Willi, and M. Cerchez. "UV harmonics generated on modulated targets irradiated by high-intensity laser pulses." Laser and Particle Beams 37, no. 01 (February 18, 2019): 12–17. http://dx.doi.org/10.1017/s0263034619000090.

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AbstractThe generation of high-order harmonics in ultraviolet spectral range by targets of periodic modulation interacting with relativistic, high contrast laser pulse (Iλ2= 1020W/cm2· μm2) was investigated experimentally and numerically. The spectral intensity of the 2nd- and 3rd-order harmonic emission from grating of different periodicities (250, 410, and 480 nm) is presented. The enhancement of the 3rd harmonic order compared with 2nd was observed for a grating of 480 nm periodicity. The experimental results indicate the role of the grating periodicity on the emission efficiency of different higher order harmonics in the UV spectral range. The higher order harmonics are emitted at the grating surface separated from the specular reflection of the laser pulse, due of the interference effects. In addition, 2D numerical PIC simulations demonstrate a complex angular distribution of the higher harmonics (HH) spectral intensity and confirm the strong dependence of the HH efficiency of a specific order on the grating periodicity, as observed experimentally. These special features of the high harmonic emission by periodically modulated targets open the route toward the control of HH spectral composition and of the emission efficiency of the lower order harmonics.

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González-López, Antonio. "Using higher order harmonics in MTF calculations." Biomedical Physics & Engineering Express 3, no. 2 (April 12, 2017): 025019. http://dx.doi.org/10.1088/2057-1976/aa6702.

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Khan, Muhammad Imran, Ahmed S. Alshammari, Badr M. Alshammari, and Ahmed A. Alzamil. "Estimation and Analysis of Higher-Order Harmonics in Advanced Integrated Circuits to Implement Noise-Free Future-Generation Micro- and Nanoelectromechanical Systems." Micromachines 12, no. 5 (May 10, 2021): 541. http://dx.doi.org/10.3390/mi12050541.

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This work deals with the analysis of spectrum generation from advanced integrated circuits in order to better understand how to suppress the generation of high harmonics, especially in a given frequency band, to design and implement noise-free systems. At higher frequencies, the spectral components of signals with sharp edges contain more energy. However, current closed-form expressions have become increasingly unwieldy to compute higher-order harmonics. The study of spectrum generation provides an insight into suppressing higher-order harmonics (10th order and above), especially in a given frequency band. In this work, we discussed the influence of transistor model quality and input signal on estimates of the harmonic contents of switching waveforms. Accurate estimates of harmonic contents are essential in the design of highly integrated micro- and nanoelectromechanical systems. This paper provides a comparative analysis of various flip-flop/latch topologies on different process technologies, i.e., 130 and 65 nm. An FFT plot of the simulated results signifies that the steeper the spectrum roll-off, the lesser the content of higher-order harmonics. Furthermore, the results of the comparison illustrate the improvement in the rise time, fall time, clock-Q delay and spectrum roll-off on the better selection of slow-changing input signals and more accurate transistor models.

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Huang, Yubo, Jundong Zhang, Dong Chen, and Zhiwei Jia. "Simulation Research on Phase Locking Technology Based on Modified DSOGI-PLL." Journal of Physics: Conference Series 2219, no. 1 (April 1, 2022): 012004. http://dx.doi.org/10.1088/1742-6596/2219/1/012004.

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Abstract For complex working conditions in power grid, it is easy to produce a large number of harmonics, and the double second-order generalized integrator phase-locked loop (DSOGI-PLL) cannot effectively suppress low-order harmonics, a new DSOGI-PLL based on modified sequential cascaded harmonic cancellation module is proposed in this paper. By designing a harmonic cancellation module that eliminates specific frequency harmonics, different frequency harmonic cancellation modules are cascaded in order from small to large to eliminate low frequency harmonics near the basic frequency. By building the simulation model, the comparison analysis verifies that the modified DSOGI-PLL has higher accuracy in tracking the frequency and phase of the voltage signal, and is more suitable for the power grid.

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Omer, Mohammad, and Farasat Munir. "Interference cancellation for higher harmonics of supply-modulated efficient RF power amplifier systems." International Journal of Microwave and Wireless Technologies 9, no. 4 (August 18, 2016): 729–39. http://dx.doi.org/10.1017/s1759078716000933.

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In building highly efficient transmitters of today, one is forced to sacrifice linearity for efficiency. Some of the highest power amplifier efficiency figures are reported by envelope tracking (ET) amplifiers. These amplifiers can generate strong higher-order harmonics, which can lead to interference with receivers operating at the harmonic frequencies. Using non-linear interference cancellation, we can help to remove the interference being caused in those receivers. This paper looks at the problem of modeling the third and second-order harmonic emission from an ET amplifier. It derives the non-linear kernel for estimating such interference. This kernel has been rigorously expanded to show its correlation with the various harmonics and its effectiveness in predicting the harmonic content. We then set up an envelope amplifier test-bench to capture harmonic signal content and cancel it using the derived kernel model. The experiment yields excellent agreement with theory and provides a validation of the system and concept.

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Ding, Desheng, and Jian-yu Lu. "Higher-order harmonics of limited diffraction Bessel beams." Journal of the Acoustical Society of America 107, no. 3 (March 2000): 1212–14. http://dx.doi.org/10.1121/1.428410.

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Hautesserres, Denis, and Martin Lara. "Intermediary LEO propagation including higher order zonal harmonics." Celestial Mechanics and Dynamical Astronomy 127, no. 4 (October 15, 2016): 505–26. http://dx.doi.org/10.1007/s10569-016-9736-6.

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Bányász, I. "Higher-order harmonics in bleached silver halide holograms." Optics and Lasers in Engineering 44, no. 9 (September 2006): 926–42. http://dx.doi.org/10.1016/j.optlaseng.2005.06.012.

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Liu, Hang, and Liqiang Feng. "Electron-Nuclear Dynamics on Amplitude and Frequency Modulation of Molecular High-Order Harmonic Generation from H2+ and its Isotopes." Zeitschrift für Naturforschung A 72, no. 10 (September 26, 2017): 941–53. http://dx.doi.org/10.1515/zna-2017-0237.

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AbstractElectron-nuclear dynamics of molecular high-order harmonic generation from H2+ and its isotopes has been theoretically investigated beyond the Born-Oppenheimer approximations. The results show that (i) due to the different ionisation probabilities and the harmonic emission times, the intensities of the harmonics from H2+ and its isotopes are very sensitive to the initial vibrational state, the pulse duration, and the pulse intensity. (ii) Due to the nonadiabatic effects in molecular high-order harmonic generation, the red-shifts of the harmonics can be found in the lower pulse intensity. With the increase of the pulse intensity, the harmonics are from the red-shifts to the blue-shifts. Moreover, as the pulse duration increases, the blue-shifts of the harmonics can be enhanced. As the initial vibrational state increases, the red-shifts of the harmonics can be decreased, whereas the blue-shifts of the harmonics can be enhanced. However, the shifts of the harmonics are decreased as the nuclear mass increases. (iii) Due to the coupled electron-nuclear dynamics in molecules, the spatial symmetry of the system is broken. As a result, non-odd harmonics can be generated at the larger internuclear distance. With the increase of the initial vibrational state or the nuclear mass, the generation of the non-odd harmonics can be enhanced and reduced, respectively. As the pulse duration or the pulse intensity increase, the generation of the non-odd harmonics can be enhanced. However, the intensities of the non-odd harmonics are decreased when using the longer pulse duration with the much higher laser intensity.

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Jia, Maoshen, Wenbei Wang, and Ziyu Yang. "2.5D Sound Field Reproduction Using Higher Order Loudspeakers." Cybernetics and Information Technologies 15, no. 6 (December 1, 2015): 5–15. http://dx.doi.org/10.1515/cait-2015-0063.

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Abstract Using 3-Dimensional (3D) sound sources as secondary sources to 2-Dimensional (2D) sound field reproduction, it is termed 2.5-Dimensional (2.5D) sound field reproduction which is currently drawing broad interest in acoustic signal processing. In this paper we propose a method to reproduce a 2D sound field, using a circular array of 3D High Order (HO) loudspeakers, which provides a mode matching solution based on 3D wave field translation. Using the spherical addition theorem, we first obtain a spherical harmonics representation of a 2D sound field reproduced by an array of HO loudspeakers. Then, the corresponding relationship between the reproduced sound field and the desired sound field is established by spherical/cylindrical harmonic expansions. Finally, the modal weights of HO loudspeakers are designed by using a least squares method. Simulation results show that the proposed method extends the reproduction region and significantly reduces the required minimum number of loudspeakers over the other referenced methods.

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Shahverdi, Amin, and Amir Borji. "The effect of higher order harmonics on second order nonlinear phenomena." Optics Communications 343 (May 2015): 124–30. http://dx.doi.org/10.1016/j.optcom.2015.01.026.

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Chen, Yanzuo, Xuxu Shen, Wendi Lan, Suyu Li, Fuming Guo, and Yujun Yang. "The High-Order Harmonic Generation from Atom Driven by Co-Rotating Laser Pulses Composed of Fundamental Frequency and High Frequency." Symmetry 14, no. 3 (March 3, 2022): 519. http://dx.doi.org/10.3390/sym14030519.

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By numerically solving the time-dependent Schrödinger equation (TDSE), the harmonic generation process of atoms irradiated by corotating laser pulses composed of a fundamental-frequency and high-frequency field is systematically studied. Compared with the harmonic generated from atoms irradiated by counter-rotating two-color circularly polarized laser pulses, the harmonic efficiency of atoms irradiated by co-rotating two-color circularly polarized (CRTCCP) laser pulses with the same laser parameters is higher. The harmonics are generated by the multiphoton radiation transition after the bound electrons undergo a multiphoton absorption transition to a higher energy level. In addition, the variation of the harmonic efficiency with the field strength of different frequency components in the driving laser pulse is also studied. The circularly polarized harmonics with higher intensity can be obtained by optimizing the field strength of the driving laser field.

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Dambrauskas, Karolis, Jonas Vanagas, Saulius Bugenis, Tomas Zimnickas, and Artūras Kalvaitis. "Methodology for Asynchronous Motor Impedance Measurement by Using Higher Order Harmonics." Energies 13, no. 10 (May 17, 2020): 2541. http://dx.doi.org/10.3390/en13102541.

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The control methods of asynchronous motors have changed during past decades. In the past, asynchronous motors were connected to grid directly. Later, thyristors as switching element-based frequency converters for asynchronous motors have appeared. Today, asynchronous motors are controlled with variable speed drives that are frequency converters consisting of IGBT power modules as switching elements that form the output voltage for asynchronous motors. Because of IGBT’s high switching speed of around few kilohertz, higher order harmonics appear in the output voltage. Their influence was not analyzed in the past as the methodology of asynchronous motor winding resistance measurement was under development. In this article, a new methodology of motor resistance measurement for mass production is introduced. The resistance—compared to higher order harmonics values between the windings of benchmark and tested motors—gives an ability to faster and more accurately determine a motor’s characteristics and losses induced by higher order harmonics that appear when a motor is powered by a variable speed drive. Motor winding’s inductance dependency on the current of magnetic biasing and the higher frequency of voltage is analyzed in this article. In addition, the simulation model of resistance to higher order harmonics of motor measurement is introduced and analyzed in this article.

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Hollinger, Richard, Paul Herrmann, Viacheslav Korolev, Maximilian Zapf, Valentina Shumakova, Robert Röder, Ingo Uschmann, et al. "Polarization Dependent Excitation and High Harmonic Generation from Intense Mid-IR Laser Pulses in ZnO." Nanomaterials 11, no. 1 (December 22, 2020): 4. http://dx.doi.org/10.3390/nano11010004.

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The generation of high order harmonics from femtosecond mid-IR laser pulses in ZnO has shown great potential to reveal new insight into the ultrafast electron dynamics on a few femtosecond timescale. In this work we report on the experimental investigation of photoluminescence and high-order harmonic generation (HHG) in a ZnO single crystal and polycrystalline thin film irradiated with intense femtosecond mid-IR laser pulses. The ellipticity dependence of the HHG process is experimentally studied up to the 17th harmonic order for various driving laser wavelengths in the spectral range 3–4 µm. Interband Zener tunneling is found to exhibit a significant excitation efficiency drop for circularly polarized strong-field pump pulses. For higher harmonics with energies larger than the bandgap, the measured ellipticity dependence can be quantitatively described by numerical simulations based on the density matrix equations. The ellipticity dependence of the below and above ZnO band gap harmonics as a function of the laser wavelength provides an efficient method for distinguishing the dominant HHG mechanism for different harmonic orders.

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Lee, An Sung, and Itzhak Green. "Higher Harmonic Oscillations in a Noncontacting FMR Mechanical Face Seal Test Rig." Journal of Vibration and Acoustics 116, no. 2 (April 1, 1994): 161–67. http://dx.doi.org/10.1115/1.2930407.

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In order to investigate experimentally the dynamic behavior of a noncontacting flexibly mounted rotor (FMR) mechanical face seal a test rig was designed and built. Test results showed that the FMR seal was vulnerable to higher harmonic oscillations with frequencies that are integer multiples of the shaft speed. Because system nonlinearities can cause higher harmonic oscillations, the dynamic moments acting on the rotor are derived to include the effects of imbalance and axial offset of the rotor. The analysis reveals that the nonlinear terms involved are of second order and generally can be neglected. Investigation is then directed to analyze the possibility of rubbing contact between the rotor and the stator. Rubbing contact can occur as a result of a high relative angular misalignment between the rotor and the stator. A contact kinematics model is proposed and a Fourier series analysis is performed on the resulting rotor response. The analysis shows that the proposed response contains higher harmonics. Fourier series expansion and numerical filtering of a sampled rotor response from the test rig yield resembling signals which contain higher harmonics. This suggests that rubbing contact is the source of higher harmonic oscillations. Design modification to the rotor flexible support system resulted in a virtual elimination of higher harmonic oscillations.

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YU WEI and XU ZHI-ZHAN. "HIGHER-ORDER HARMONICS EMISSION IN CO2-LASER IRRADIATED TARGETS." Acta Physica Sinica 36, no. 2 (1987): 224. http://dx.doi.org/10.7498/aps.36.224.

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Ding, De-Sheng, and Jin-Huang Huang. "Higher-order harmonics of general limited diffraction Bessel beams." Chinese Physics B 25, no. 12 (November 29, 2016): 124307. http://dx.doi.org/10.1088/1674-1056/25/12/124307.

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Barlett, Martin L., G. Douglas Meegan, and Gary R. Wilson. "Detection of narrowband harmonics using higher‐order spectral methods." Journal of the Acoustical Society of America 100, no. 4 (October 1996): 2575. http://dx.doi.org/10.1121/1.417495.

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Zhou, Hongjun, Jinjin Zheng, Tonglin Huo, Guobin Zhang, Zeming Qi, and Pengfei Zhong. "Quantitative research on higher order harmonics in metrology beamline." Frontiers of Electrical and Electronic Engineering in China 3, no. 1 (January 2008): 105–9. http://dx.doi.org/10.1007/s11460-008-0021-7.

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Huang, Y., and K. L. Chan. "Texture Decomposition by Harmonics Extraction From Higher Order Statistics." IEEE Transactions on Image Processing 13, no. 1 (January 2004): 1–14. http://dx.doi.org/10.1109/tip.2003.819432.

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Jegathesan, V. "GENETIC ALGORITHM BASED SOLUTION IN PWM CONVERTER SWITCHING FOR VOLTAGE SOURCE INVERTER FEEDING AN INDUCTION MOTOR DRIVE." ASEAN Journal on Science and Technology for Development 27, no. 2 (November 21, 2017): 45–60. http://dx.doi.org/10.29037/ajstd.251.

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This paper presents an efficient and reliable Genetic Algorithm based solution for Selective Harmonic Elimination (SHE) switching pattern. This method eliminates considerable amount of lower order line voltage harmonics in Pulse Width Modulation (PWM) inverter. Determination of pulse pattern for the elimination of some lower order harmonics of a PWM inverter necessitates solving a system of nonlinear transcendental equations. Genetic Algorithm is used to solve nonlinear transcendental equations for PWM-SHE. Many methods are available to eliminate the higher order harmonics and it can be easily removed. But the greatest challenge is to eliminate the lower order harmonics and this is successfully achieved using Genetic Algorithm without using Dual transformer. Simulations using MATLABTM and Powersim with experimental results are carried out to validate the solution. The experimental results show that the harmonics up to 13th were totally eliminated.

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Jegathesan, V. "Genetic algorithm based solution in pwm converter switching for voltage source inverter feeding an induction motor drive." ASEAN Journal on Science and Technology for Development 26, no. 2 (November 27, 2017): 45–60. http://dx.doi.org/10.29037/ajstd.321.

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This paper presents an efficient and reliable Genetic Algorithm based solution for Selective Harmonic Elimination (SHE) switching pattern. This method eliminates considerable amount of lower order line voltage harmonics in Pulse Width Modulation (PWM) inverter. Determination of pulse pattern for the elimination of some lower order harmonics of a PWM inverter necessitates solving a system of nonlinear transcendental equations. Genetic Algorithm is used to solve nonlinear transcendental equations for PWM-SHE. Many methods are available to eliminate the higher order harmonics and it can be easily removed. But the greatest challenge is to eliminate the lower order harmonics and this is successfully achieved using Genetic Algorithm without using Dual transformer. Simulations using MATLABTM and Powersim with experimental results are carried out to validate the solution. The experimental results show that the harmonics up to 13th were totally eliminated.

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Penoyre, Zephyr, and Emily Sandford. "Higher order harmonics in the light curves of eccentric planetary systems." Monthly Notices of the Royal Astronomical Society 488, no. 3 (July 25, 2019): 4181–94. http://dx.doi.org/10.1093/mnras/stz1941.

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ABSTRACTAs a planet orbits, it causes periodic modulations in the light curve of its host star. Due to the combined effects of the planet raising tides on the host star, relativistic beaming of the starlight, and reflection of light off the planet’s surface, these modulations occur at the planet’s orbital frequency, as well as integer multiples of this frequency. In particular, planets on eccentric orbits induce third and higher order harmonics in the stellar light curve which cannot be explained by circular-orbit models. Even at moderate eccentricities, such as those typical of Solar system planets, these harmonics are detectable in current and future photometric data. We present an analysis of the harmonics caused by tides, beaming, and reflection in eccentric planetary systems. We explore the dependence of these signals on the parameters of the system, and we discuss prospects for current and future observations of these signals, particularly by the NASA TESS mission. Finally, we present publicly available code for computation of light curves with tidal, beaming, and reflection signals, oot.

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Korolova, Olga, Juan Torre Cubillo, and Bernd Ponick. "TRANSIENT MODELING OF AC MACHINES CONSIDERING SECOND ORDER EFFECTS." Informatyka Automatyka Pomiary w Gospodarce i Ochronie Środowiska 8, no. 2 (May 30, 2018): 4–8. http://dx.doi.org/10.5604/01.3001.0012.0695.

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In this paper, the transient simulation of AC machines considering spatial field harmonics and current displacement in rotor bars is examined. The first point of discussion is the sufficient order of the equivalent circuit of the current displacement model for its accurate co-simulation with the higher spatial field harmonics. In the second place, the problem of inversion of the inductance matrix considering the flux linkage through higher spatial harmonics is studied.

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Zhao, Xiaofan, Hongye Li, Binyu Rao, Meng Wang, Baiyi Wu, and Zefeng Wang. "Spectral Characteristics of Square-Wave-Modulated Type II Long-Period Fiber Gratings Inscribed by a Femtosecond Laser." Sensors 21, no. 9 (May 10, 2021): 3278. http://dx.doi.org/10.3390/s21093278.

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We study here the spectral characteristics of square-wave-modulated type II long-period fiber gratings (LPFGs) inscribed by a femtosecond laser. Both theoretical and experimental results indicate that higher-order harmonics refractive index (RI) modulation commonly exists together with the fundamental harmonic RI modulation in such LPFGs, and the duty cycle of a square wave has a great influence on the number and amplitudes of higher-order harmonics. A linear increase in the duty cycle in a series of square wave pulses will induce another LPFG with a minor difference in periods, which is useful for expanding the bandwidth of LPFGs. We also propose a method to reduce insertion loss by fabricating type II LPFGs without higher-order harmonic resonances. This work intensifies our comprehension of type II fiber gratings with which novel optical fiber sensors can be fabricated.

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Lange, Andrzej Grzegorz, and Grzegorz Redlarski. "Selection of C-Type Filters for Reactive Power Compensation and Filtration of Higher Harmonics Injected into the Transmission System by Arc Furnaces." Energies 13, no. 9 (May 7, 2020): 2330. http://dx.doi.org/10.3390/en13092330.

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This article presents a method for selecting the elements of a C-type filter working with a conventional LC-type filter for compensating reactive power and filtering out higher harmonics generated by arc furnaces and ladle furnaces. The study was conducted in a steel mill supplied by a 110 kV transmission system, where higher harmonic currents and nonlinear loads were measured. A series of computer simulations were performed under various operating conditions, and an algorithm for selecting the parameters of a third-order C-type filter (for suppressing the second harmonic) and two second-order LC-type filters (for suppressing the third harmonic) was proposed. The filtering system was tested in an arc furnace with the highest rated power, and harmonics in the current spectrum were evaluated. The results of the measurements were used to analyze the effectiveness of the compensation system comprising two passive C-type and LC-type filters at different system configurations. C-type filters significantly influenced current harmonics. The influence of the changes in the number of arc furnace transformers on the true Root Mean Square (RMS) of the currents injected into the 110 kV transmission system and on the voltages of the 110 kV busbars was discussed.

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Ganeev, Rashid A., Vyacheslav V. Kim, Konda Srinivasa Rao, and Chunlei Guo. "Probing Laser Plasma Dynamics Using High-Order Harmonics Generation in Carbon-Containing Nanomaterials." Applied Sciences 11, no. 5 (February 28, 2021): 2143. http://dx.doi.org/10.3390/app11052143.

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We study high-order harmonics generation from plasmas generated from graphite, fullerenes, carbon nanotubes, carbon nanofibers, diamond nanoparticles, and graphene. Our approach utilizes a heating nanosecond laser pulse to produce plasmas that serve as the media for high harmonic generation from a subsequent driven femtosecond laser pulse. High harmonics are generated at different time delays following the plasma formation, which allows us to analyze the spreading of species with different masses. We analyze the harmonic yields from species of single carbon atom, 60 atoms (fullerene), 106 atoms (diamond nanoparticles), 109 atoms (CNTs and CNFs), and even much larger species of graphene sheets. The harmonic yields are analyzed in the range of 100 ns–1 ms delays. The harmonic yields were significantly higher within the 200 ns–0.5 µs range, but no harmonic is observed between 10 µs–1 ms. Our observations show that, at the optimal ablation of atoms and clusters, the laser-induced plasmas produced on the surfaces of different carbon-contained species spread out from targets with the comparable velocities.

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Wang, Xiangrong, and Guangtian Shi. "Analysis of harmonic influence of improved PFC circuit on SS4G electric locomotive." Journal of Physics: Conference Series 2260, no. 1 (April 1, 2022): 012032. http://dx.doi.org/10.1088/1742-6596/2260/1/012032.

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Abstract Compared with active filter, PFC circuit has simple structure and convenient operation. Introducing it into SS4G electric locomotive can greatly reduce system harmonics. Therefore, firstly, the corresponding PFC circuit is built, and the suppression measures of peak section and discontinuous section are proposed. By improving the discontinuous section, the waveform conduction angle is expanded from 129.564° to 162.882°. Accordingly, the current harmonic at the input side is reduced from 27.38% to 16.19%. After the voltage multiplier is further introduced, the harmonic is reduced to 15.77%. Then, the circuit is designed to absorb the high-order harmonic power in the peak section, and the harmonic is further reduced by about 0.33% to 15.44%. Two small order smoothing capacitors are connected in parallel in the load section to further absorb higher harmonics, which can reduce harmonics to 9.95%. Because the discontinuous section will also produce some spikes in the improvement process, improving the spikes can reduce the harmonics by 4.42% to 5.53%. Then the final improved circuit is introduced into SS4G circuit, and the current harmonic content of the circuit is reduced from 30.02% to 15.59%. The improved PFC circuit has achieved good results in SS4G.

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Hussein, A. M. "Generation and radiation of third harmonics by an electrostatic wave in a narrow inhomogeneous layer of a warm plasma." Journal of Plasma Physics 45, no. 2 (April 1991): 153–57. http://dx.doi.org/10.1017/s0022377800015609.

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An investigation is made of wave generation and the radiation of third harmonics by an electrostatic wave in a narrow inhomogeneous layer of a warm plasma. The amplitudes of the third-harmonic wave are calculated. It is found that they depend both on the nonlinear interaction of the initial waves and on the interaction of second harmonics with the initial wave. The generation of third harmonics by interaction of the initial waves is a four-wave process, i.e. a higher-order nonlinearity.

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35

Lare, Pakedam, Byamakesh Nayak, Srikanta Dash, and Jiban Ballav Sahu. "Adaptive Phase-Shifted PWM based on Particle Swarm Optimization for Cascaded H-Bridge Inverter with Unequal Dc-link Voltages." International Journal of Engineering & Technology 7, no. 4.15 (October 7, 2018): 469. http://dx.doi.org/10.14419/ijet.v7i4.15.25756.

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The cascaded H-Bridge Multilevel Inverter has been found a promising technology in industrial applications because of its higher voltage with less distortion production. Various PWMs techniques have been proposed to push the harmonics frequencies higher than the switching frequency and thus reduces the THD as compared to non-carrier control technique based upon grid frequency. The Phase-Shifted PWM technique has an advantage over others PWM techniques because its harmonics orders are multiples of switching frequency and also depend on the number of levels of the inverter. The phase shifting angle is uniform when the equal voltage sources are adopted. However, in applications where sets of different voltage source levels feed the H-Bridge cells, the Phase Shifted PWM suffers its high order harmonics elimination capability. As a solution to alleviate this problem, an adaptive variable angle approach is proposed in this paper using Particle Swarm Optimization (PSO) algorithm to eliminate desired higher order harmonics. The algorithm is used to minimize the cost function based on high order sideband harmonics elimination equations. The results through MATLAB/Simulink environment shown in this paper confirm the reduction of sideband harmonics of higher orders, and the overall THD.

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Zhou Hong-jun, 周洪军, 王冠军 Wang Guan-jun, 郑津津 Zheng Jin-jin, and 霍同林 Huo Tong-lin. "Triple reflector polarizer integrated with suppression of higher order harmonics." Optics and Precision Engineering 19, no. 10 (2011): 2314–18. http://dx.doi.org/10.3788/ope.20111910.2314.

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Guotong Zhou and G. Giannakis. "On estimating random amplitude-modulated harmonics using higher order spectra." IEEE Journal of Oceanic Engineering 19, no. 4 (1994): 529–39. http://dx.doi.org/10.1109/48.338389.

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Giannessi, L., H. P. Freund, P. Musumeci, and S. Reiche. "Higher-order harmonics coupling in different free-electron laser codes." Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 593, no. 1-2 (August 2008): 143–47. http://dx.doi.org/10.1016/j.nima.2008.04.075.

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Svoboda, P., T. Reif, M. Loewenhaupt, M. Rotter, E. Gratz, and G. McIntyre. "Observation of higher-order harmonics in AF2 phase of NdCu2." Physica B: Condensed Matter 234-236 (June 1997): 642–43. http://dx.doi.org/10.1016/s0921-4526(96)01070-8.

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Ning, D., X. Zhuo, L. Chen, and B. Teng. "Nonlinear Numerical Investigation on Higher Harmonics at Lee Side of a Submerged Bar." Abstract and Applied Analysis 2012 (2012): 1–12. http://dx.doi.org/10.1155/2012/214897.

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The decomposition of a monochromatic wave over a submerged object is investigated numerically in a flume, based on a fully nonlinear HOBEM (higher-order boundary element method) model. Bound and free higher-harmonic waves propagating downstream the structure are discriminated by means of a two-point method. The developed numerical model is verified very well by comparison with the available data. Further numerical experiments are carried out to study the relations between free higher harmonics and wave nonlinearity. It is found that thenth-harmonic wave amplitude is growing proportional to thenth power of the incoming wave amplitude for weakly nonlinear wave condition, but higher-harmonic free wave amplitudes tend to a constant value for strong nonlinear wave condition.

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Vojnovic, Nebojsa, Lorenzo Crocco, and Marija Nikolic Stevanovic. "A Three-Dimensional Microwave Sparse Imaging Approach Using Higher-Order Basis Functions." International Journal of Antennas and Propagation 2022 (March 23, 2022): 1–20. http://dx.doi.org/10.1155/2022/1839842.

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This paper presents a novel method for three-dimensional microwave imaging based on sparse processing. To enforce the sparsity of the unknown function, we take advantage of the fact that arbitrary three-dimensional electromagnetic fields can be decomposed into two components with respect to the radial direction: one with transverse-magnetic polarization and the other with transverse-electric polarization. Each component can be further expressed as a sum of spherical harmonics, which provide the dictionary exploited by the sparse processing algorithm. Our measurement model relates the data and the parameters of the spherical harmonics’ sources, which are uniformly distributed on a grid sampling the imaging domain. By relying on the theory of degrees of freedom of electromagnetic fields, it can be shown that only a few harmonics are sufficient to accurately represent the measured scattered field from objects whose diameter is of the order of the wavelength, thus allowing reducing the dimension of the adopted dictionary. We analyze several imaging scenarios to assess the algorithm’s performance, including different object shapes, sensor orientations, and signal-to-noise ratios. Moreover, we compare the obtained results with other state-of-the-art linear imaging techniques. Notably, thanks to the adopted dictionary, the proposed algorithm can yield accurate images of both convex and concave objects.

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Taleb, Rachid, M’hamed Helaimi, Djilali Benyoucef, and Zinelaabidine Boudjema. "Genetic Algorithm Application in Asymmetrical 9-Level Inverter." International Journal of Power Electronics and Drive Systems (IJPEDS) 7, no. 2 (June 1, 2016): 521. http://dx.doi.org/10.11591/ijpeds.v7.i2.pp521-530.

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Selective harmonic elimination (SHE) has been a widely researched alternative to traditional PWM techniques. This paper presents the selective harmonic elimination of a uniform step asymmetrical multilevel inverter (USAMI) using genetic algorithm (GA) which eliminates specified higher order harmonics while maintaining the required fundamental voltage. This technique can be applied to USAMI with any number of levels. As an example, in this paper a 9-level USAMI is considered and the optimum switching angles are calculated to eliminate the 5th, 7th and 11th harmonics.

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MIDORIKAWA, KATSUMI, SHOICHI KUBODERA, HIDEO TASHIRO, and KOICHI TOYODA. "RECENT PROGRESS ON HIGH-ORDER HARMONIC GENERATION USING LASER-PRODUCED IONS." Modern Physics Letters B 07, no. 24n25 (October 30, 1993): 1533–46. http://dx.doi.org/10.1142/s0217984993001570.

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The recent progress of the high-order harmonic generation in laser-produced ions is presented. The experimental results obtained at RIKEN using a 500-fs KrF laser (248 nm) are summarized. Rare gas-like ions produced much higher-order harmonics than rare gases did when the laser intensity was increased to 1017 W/cm 2. In addition to rare gas-like ions, various metal ions were used as nonlinear media. The maximum harmonic orders are found to be simply proportional to the ionization potentials of the nonlinear media, including neutral rare gases. The maximum harmonic order observed was the 21st (11.8 nm) in Pb 2+. The advantages of using ions in laser-produced plasmas as nonlinear media for the high-order harmonic generation are discussed.

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Akay, Ali, and Paul Lefley. "Torque Ripple Reduction Method in a Multiphase PM Machine for No-Fault and Open-Circuit Fault-Tolerant Conditions." Energies 14, no. 9 (May 2, 2021): 2615. http://dx.doi.org/10.3390/en14092615.

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This paper presents a method that has been developed to reduce the torque ripples under healthy and open-circuit fault-tolerant (OCFT) conditions for a multiphase permanent magnet (PM) machine. For smooth torque, both the phase current and the back electromotive force (back-EMF) should be purely sinusoidal. To improve the torque in a multiphase machine, higher-order current harmonics are injected, which are related to the harmonics in the back-EMF. For this reason, generally, multiphase machines are designed with higher-order back-EMF harmonics. However, these harmonics produce ripples in the torque. In light of this, a torque ripple cancellation method has been developed that first determines an additional current component from the harmonic content of the back-EMF and then injects these additional components to cancel the torque ripple. It has been found that this new torque ripple cancellation method works for both faultless and faulty conditions in a five-phase PM machine. The method has been validated using Finite Element Analysis, and the results are presented in this paper.

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Prasath, V., S. Vijayalakshmi, and R. Jain Anush. "PMSG Based WECS with PR Control Strategy for Grid Control." Applied Mechanics and Materials 573 (June 2014): 267–72. http://dx.doi.org/10.4028/www.scientific.net/amm.573.267.

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In this paper, a current feedback control scheme is proposed using Proportional Resonant (PR) for a grid-connected converter with an LCL Filter; PR controller with harmonic compensators has high gain at the desired frequencies for decrease harmonic distortion in the alternative voltage or current. Harmonic compensators of PR controller are limited to several low-order harmonics due to the system instability when the compensated frequency is out of system control loop’s bandwidth. The average value of current flow through inductors of LCL filter is feedback to the PR current regulator. Zero D-axis Control (ZDC) is to control the generator side converter to reduce the DC-link ripples, multi-loop harmonic current controllers are applied to regulate the higher-order harmonics by PR regulators. Consequently control strategy with LCL filter is to reduce third-order function to first-order function. By this way large control loop gain can be chosen to obtain control loop for the required harmonic components of the PR controller. The simulation and experimental results have been illustrated to validate the effectiveness of the proposed method in MATLAB Simulink.

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Rens, Jan, Lode Vandenbossche, and Ophélie Dorez. "Iron Loss Modelling of Electrical Traction Motors for Improved Prediction of Higher Harmonic Losses." World Electric Vehicle Journal 11, no. 1 (March 11, 2020): 24. http://dx.doi.org/10.3390/wevj11010024.

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A Finite Element (FE) modelling approach is presented to account for the core losses in electrical machines that are generated by higher harmonic frequencies, for example those caused by Pulse Width Modulation (PWM) switching or by space harmonics due to the machine geometry. The model builds further on a post-processing calculation tool that was recently developed to take into account the magnetic skin effect in electrical steel laminations at high frequencies, and extends this by a more detailed loss analysis of the minor hysteresis loops that are caused by the higher harmonics. Further, these tools for high-frequency loss analysis are integrated into a complete electrical machine model with separate consideration of the major and minor loops. The modelling approach relies strongly on extensive magnetic measurement data of the electrical steel, in order to accurately predict the different loss components for minor hysteresis loops as a function of the DC bias field, frequency and amplitude of the minor loop. Results from the model are shown for an automotive traction motor, illustrating the losses caused by PWM harmonics and demonstrating the relevance of including the skin effect in these calculations.

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Venkatesh, S. "Design and Implementation of Grid Connected Solar Inverter using Adaptive Harmonic Elimination Technique." International Journal for Research in Applied Science and Engineering Technology 9, no. VI (June 30, 2021): 5123–29. http://dx.doi.org/10.22214/ijraset.2021.36082.

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Our project mainly focuses work a lot being carried out in the ﬁeld of distributed generation. For the electric grid, so Many distributed generation systems are being made. At this time when the non-renewable sources of energy such as oil, coal, etc are very fast disappearing, a study of distributed generation systems (DGs) and Establishing of such systems using renewable sources of energy becomes very important. we have seen several major problems will happen, when harmonic content of the current is flows into the grid, like this issue several issues are going to meet. When a Distribution Generation source is being linked to the grid. “The current being injected should have harmonic content conforming to standards such as IEEE 512-1992”[1].To limit the harmonic current injected into the grid. The hardware is tailor-made to be used for a solar PV panels based distributed generation system. This project deals mainly with Establishing the hardware for a grid connected inverter. This means that a proper plan of action should be present in the required system, special type of filters are made to abolish higher order harmonics, this is only the reason why filters would be less bulky and cheap. only the higher order harmonics are decreased by specially made filters, Lower order harmonics are attenuated by a technique called “an adaptive harmonic elimination technique (AHE). In our project we need to develop several blocks called the inverter hardware, design and implementation of closed loop control, transformer, the filters along with adaptive selective harmonic elimination scheme

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Pagano, P., D. J. Pascoe, and I. De Moortel. "Contribution of phase-mixing of Alfvén waves to coronal heating in multi-harmonic loop oscillations." Astronomy & Astrophysics 616 (August 2018): A125. http://dx.doi.org/10.1051/0004-6361/201732251.

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Context. Kink oscillations of a coronal loop are observed and studied in detail because they provide a unique probe into the structure of coronal loops through magnetohydrodynamics (MHD) seismology and a potential test of coronal heating through the phase mixing of Alfvén waves. In particular, recent observations show that standing oscillations of loops often involve higher harmonics in addition to the fundamental mode. The damping of these kink oscillations is explained by mode coupling with Alfvén waves. Aims. We investigate the consequences for wave-based coronal heating of higher harmonics and which coronal heating observational signatures we may use to infer the presence of higher harmonic kink oscillations. Methods. We performed a set of non-ideal MHD simulations in which we modelled the damping of the kink oscillation of a flux tube via mode coupling. We based our MHD simulation parameters on the seismological inversion of an observation for which the first three harmonics are detected. We studied the phase mixing of Alfvén waves, which leads to the deposition of heat in the system, and we applied seismological inversion techniques to the MHD simulation output. Results. We find that the heating due to phase mixing of Alfvén waves triggered by the damping of kink oscillation is relatively small. We can however illustrate how the heating location drifts from subsequent damping of lower order harmonics. We also address the role of higher order harmonics and the width of the boundary shell in the energy deposition. Conclusions. We conclude that the coronal heating due to phase mixing does not seem to provide enough energy to maintain the thermal structure of the solar corona even when multi-harmonic oscillations are included; these oscillations play an inhibiting role in the development of smaller scale structures.

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Pei, Li, Guo, Yang, and Du. "A Novel Rotor Eddy Current Loss Estimation Method for Permanent Magnet Synchronous Machines with Small Inductance and a Conductive Rotor Sleeve." Energies 12, no. 19 (September 30, 2019): 3760. http://dx.doi.org/10.3390/en12193760.

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Typically, permanent magnet synchronous machines (PMSMs) with small inductance can achieve a higher power density and higher power factor. Thus, in many industrial applications, more and more PMSMs are being designed with small inductance. Compared with traditional PMSMs, current harmonics in small inductance PMSMs are much more abundant, and the amplitudes are usually high. These current harmonics will cause large eddy current losses (ECLs) on the rotor, making the estimation of ECLs necessary in the design stage. Currently, ECL estimation methods are usually based on frequency order information, which cannot tell the travelling direction of the harmonic magneto-wave, resulting in the inaccuracy of the estimation. This article proposes a novel estimation method based on the mechanism of the formation of space-vector pulse width modulation (PWM), which considers both the frequency order and travelling direction of the harmonic wave, resulting in the improvement of the accuracy. Besides this, by using double Fourier analysis (DFA) instead of traditional fast Fourier analysis (FFA), the predicted frequencies of the current harmonics are more accurate and free of the troubles caused by traditional FFA-based methods. Simulation study and experiments are conducted to show the effectiveness of the proposed method.

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Feng, Liqiang, and John Mccain. "Control of high-order harmonics from H2+ and D2+ for producing intense single attosecond pulse." Modern Physics Letters B 34, no. 17 (March 31, 2020): 2050192. http://dx.doi.org/10.1142/s0217984920501924.

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Generally, the intensities of molecular high-order harmonic spectra from [Formula: see text] and its isotope molecules are quite different due to the effect of nuclear signals. Thus, in this paper, we investigate the change law of harmonic spectra from [Formula: see text] and [Formula: see text] driven by different laser fields and try to find the optimal harmonic spectra for producing intense single attosecond pulses (SAPs). The results show that in lower laser intensity case, the harmonic yield follows as [Formula: see text]; while, in higher laser intensity case, the harmonic yield meets the condition of [Formula: see text]. Further, by using this change law of harmonic yield and choosing the optimal harmonic emission peak (HEP), we can obtain the intense spectral continuum with the assistance of the half-cycle pulse (HCP). Next, with the superposition of some harmonics on the spectral continuum, the intense SAPs shorter than 37 as can be obtained from [Formula: see text] and [Formula: see text] harmonic spectra. Finally, the results show that the stronger attosecond signals can be obtained when the light nucleus or heavy nucleus molecules are driven by lower or higher laser intensities, respectively.

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Journal articles on the topic 'Higher order harmonics'

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