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[IEEE 2019 IEEE Workshop on Power Electronics and Power Quality Applications (PEPQA) - Manizales, Colombia (2019.5.30-2019.5.31)] 2019 IEEE Workshop on Power Electronics and Power Quality Applications (PEPQA) - Integration of Photovoltaic System in Low Voltage Electrical Network of the Electrical Engineering Building
摘要： The quantification of the impacts of photovoltaic system (PV) integration in the low voltage (LV) power grid is necessary for the historical evaluation of the electrical network with and without PV penetration. This paper presents the study case of the LV electrical network of a university building (Colombia), which has a 9.1 kW PV system. Specifically, the electrical variables monitored were voltages (V), frequency (f), active power (W), voltage distortion (THDv), and harmonics at the Point of Common Coupling (PCC), to determine impairments according to Std. IEEE 1547-2018. PV systems could change the RMS value of voltage at the PCC, therefore, this variable was analysed. Likewise, the frequency was analysed to corroborate the no affectation of the interconnection of the PV system to the electrical network; it is due to the absence of rotational inertia. The solar irradiation information was measured by a pyranometer and the electrical variables by an smart meter, recording the information every 10 minutes for 32 days. The above is an initial step for a comprehensive evaluation of electrical variables with PV generation and future integration of parameters for the resilience evaluation of the electric network.
关键词： harmonics,frequency,photovoltaic systems,resilience,voltage,irradiation solar,Distributed generation
更新于2025-09-11 14:15:04
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Role of quantum orbits in odd-even high harmonic generation from atoms in bichromatic laser fields
摘要： We study high-order harmonic generation from atoms in bichromatic laser fields numerically and analytically. With the weak increase of the second harmonic field, the calculated odd and even HHG spectra differ remarkably from each other in some energy regions. Our analyses reveal that the interference of two neighboring quantum orbits plays an important role in this phenomenon. In particular, we show that with a trajectory-resolved approach, the emission of odd or even harmonics can be effectively controlled in a wide HHG energy region. Our results suggest a potential approach for generating even-harmonic-dominating attosecond pulse.
关键词： odd-even harmonics,bichromatic laser fields,attosecond pulse,quantum orbits,high-order harmonic generation
更新于2025-09-11 14:15:04
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Resonance Enhancement in Laser-Produced Plasmas (Concepts and Applications) || Resonance Enhancement of Harmonics in Metal-Ablated Plasmas: Early Studies
摘要： In this subsection, the first observation of an exceptionally strong resonance enhancement of a single harmonic in a plateau region is described. This phenomenon was observed during investigations of harmonic generation from femtosecond pulse interacting with indium plasma. A very strong 13th harmonic generation (λ = 61.2 nm), almost 2 orders of magnitude, exceeding the intensities of neighboring harmonics in the plateau range was observed in those studies [1].
关键词： harmonics,femtosecond pulse,extreme ultraviolet,indium plasma,resonance enhancement
更新于2025-09-11 14:15:04
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Grid Connected-Photovoltaic System (GC-PVS): Issues and Challenges
摘要： Smart grid is the key technology for an effective utilization of the Renewable Energy Sources (RES). The utilization of RES for the generation of electricity is increasingly gaining interest of researchers during the last decades. The main reason behind this is global incentivization, the increasing price of petroleum products, climate issues and deregulations in the energy market. As the Government of India, (MNRE i.e. Ministry of New & Renewable Energy) is targeting to generate 20000 MW power through grid-connected solar PVS by the year 2022 therefore, the main focus in this paper has been presented on power generation through grid-connected PVS. The emerging smart grid technology has enabled the grid-connected PVS as an evolving process in today’s world for electrical power generation. However, apart from so many advantages, there are several issues and challenges associated with the integration of PVS to the electric utility grid hence, the investigation to find out available possible solutions to overcome these issues becomes essential in order to enhance the performance of grid-connected PVS. The most severe constraint associated with this emerging technology is it high penetration level. If during low load conditions there is some mismatch found between the real power output and the load profile characteristics of PVS then it may result into large reverse power flow, high power losses or severe voltage violation. In this paper, several issues and challenges associated with the integration of solar PVS with the electric utility grid are presented.
关键词： Renewable Energy Sources,Grid Connected-Photovoltaic System,harmonics,voltage stability,RES,frequency stability,smart grid,GC-PVS
更新于2025-09-11 14:15:04
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[IEEE 2019 54th International Universities Power Engineering Conference (UPEC) - Bucharest, Romania (2019.9.3-2019.9.6)] 2019 54th International Universities Power Engineering Conference (UPEC) - Harmonic Behaviour of RGB WLED
摘要： For the last few years, there has been a decrease in electricity consumption for lighting purposes. The reason for this decrease is the widespread use of energy saving lighting elements that have high efficacy factor. LEDs are one of these lighting elements and have a very important role on energy saving lighting. On the other hand, power quality problems have started to be experienced more frequently and seriously, so it has become an important issue nowadays. Light emitting diodes are a closely related in both subjects. In this study, the harmonic behavior of RGB WLEDs, which has gained importance recently and has become increasingly widespread, has been investigated. RGB WLEDs, which are quite different from monochrome LEDs in terms of package contents and driver circuit, are expected to behave differently in terms of harmonics. In order to observe that, an appropriate test setup has been established and the power quality measurements of an RBG WLED sample have been performed for different operating cases. In the conclusion of the study, the enlightening results about the harmonic behavior of RGB WLEDs were obtained.
关键词： RGB WLED,Light emitting diodes,Distortion measurement,Relative spectral power,Power conversion harmonics
更新于2025-09-11 14:15:04
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[IEEE 2019 IEEE Photonics Conference (IPC) - San Antonio, TX, USA (2019.9.29-2019.10.3)] 2019 IEEE Photonics Conference (IPC) - Effects of the Pump Wavelength on Laser-Induced Ultrafast Demagnetization
摘要： A high harmonics source is used to perform x-ray resonant magnetic scattering on a magnetic sample. The dynamics of laser-induced ultrafast demagnetization are probed with respect to the wavelength of the pump beam. Longer pump wavelengths are found to increase the initial quenching levels.
关键词： high harmonics generation,magnetic dynamics,ultrafast demagnetization
更新于2025-09-11 14:15:04
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Intense vortex high-order harmonics generated from laser-ablated plume
摘要： In this study, we demonstrate intense extreme-ultraviolet optical vortices generated using laser-ablation plume as the nonlinear medium. We used two types of plumes that are known to generate intense high-order harmonics for driving lasers with Gaussian beam profiles, but through different mechanisms, namely, carbon (diatomic carbon molecules) and tin (resonance with the autoionizing state). We find that the harmonic fluxes for diatomic carbon molecules are similar for Gaussian and vortex driving fields. However, for harmonics from the autoionizing state of tin (~26.3 eV), the enhancement factor of the resonant harmonic intensity decreases by ~50% when using the vortex driving field. The intense extreme-ultraviolet optical vortices demonstrated in this study will be useful for many applications including a material characterization technique known as optical angular momentum dichroism as well as the spectroscopy of spin-forbidden electronic transitions.
关键词： optical angular momentum dichroism,laser-ablation plume,spin-forbidden electronic transitions,extreme-ultraviolet optical vortices,high-order harmonics,diatomic carbon molecules,autoionizing state
更新于2025-09-11 14:15:04
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Terahertz Nonlinear Optics of Graphene: From Saturable Absorption to High‐Harmonics Generation
摘要： Graphene has long been predicted to show exceptional nonlinear optical properties, especially in the technologically important terahertz (THz) frequency range. Recent experiments have shown that this atomically thin material indeed exhibits possibly the largest nonlinear coefficients of any material known to date, paving the way for practical graphene-based applications in ultrafast (opto-)electronics operating at THz rates. Here the advances in the booming field of nonlinear THz optics of graphene are reported, and the state-of-the-art understanding of the nature of the nonlinear interaction of graphene with the THz fields based on the thermodynamic model of electron transport in graphene is described. A comparison between different mechanisms of nonlinear interaction of graphene with light fields in THz, infrared, and visible frequency ranges is also provided. Finally, the perspectives for the expected technological applications of graphene based on its extraordinary THz nonlinear properties are summarized. This report covers the evolution of the field of THz nonlinear optics of graphene from the very pioneering to the state-of-the-art works. It also serves as a concise overview of the current understanding of THz nonlinear optics of graphene and as a compact reference for researchers entering the field, as well as for the technology developers.
关键词： terahertz,high-harmonics generation,nonlinear optics,thermodynamic model,graphene
更新于2025-09-11 14:15:04
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Two-dimensional projection Monte Carlo estimators for the study of angular characteristics of polarized radiation
摘要： The paper presents a Monte Carlo algorithm for the study of bidirectional angular characteristics of a scattered polarized radiation based on projection expansion of the density of the corresponding angular distribution over hemispherical harmonics. The results of numerical estimation of two-dimensional angular distributions of the intensity and the polarization degree of the radiation passed through and reflected from optically thick layers of scattering and absorbing substance are presented.
关键词： statistical modelling,radiation transfer,Monte Carlo methods,orthogonal expansion,hemispherical harmonics
更新于2025-09-11 14:15:04
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[IEEE 2018 43rd International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz2018) - Nagoya, Japan (2018.9.9-2018.9.14)] 2018 43rd International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Ultrafast Control of Even-Order Harmonic Generation from Solids by an Intense Terahertz Field
摘要： Nonperturbative even-order harmonics, physically forbidden in centrosymmetric crystals, are observed from both insulator (diamond) and semiconductor (silicon) samples driven by IR pulses, when in addition an intense THz electric field is applied to the solid. The time-resolved study of the high-harmonic spectra with the temporal profile of the THz electric field suggests a transient THz-field-induced symmetry reduction. We also investigate the harmonics’ yields depending on the angles of the linear IR and THz polarizations with respect to the crystal axes. This work might pave the way for THz-based symmetry control in solids with important ramifications for petahertz electronics.
关键词： symmetry reduction,petahertz electronics,Nonperturbative even-order harmonics,THz electric field,centrosymmetric crystals
更新于2025-09-10 09:29:36