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- 摘要
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- 实验方案
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[IEEE 2018 IEEE 15th International Symposium on Biomedical Imaging (ISBI 2018) - Washington, DC (2018.4.4-2018.4.7)] 2018 IEEE 15th International Symposium on Biomedical Imaging (ISBI 2018) - An analytical fiber ODF reconstruction in 3D polarized light imaging
摘要： Three dimensional polarized light imaging (3D-PLI) utilizes the birefringence in postmortem tissue to map its spatial fiber structure at a submillimeter resolution. We propose an analytical method to compute the fiber orientation distribution function (ODF) from high-resolution vector data provided by 3D-PLI. This strategy enables the bridging of high resolution 3D-PLI to diffusion magnetic resonance imaging with relatively low spatial resolution. First, the fiber ODF is modeled as a sum of K orientations on the unit sphere and expanded with a high order spherical harmonics series. Then, the coefficients of the spherical harmonics are derived directly with the spherical Fourier transform. We quantitatively validate the accuracy of the reconstruction against synthetic data and show that we can recover complex fiber configurations in the human heart at different scales.
关键词： spherical harmonics,3D-PLI,spherical Fourier transform,fiber orientation distribution function ODF,polarized light imaging
更新于2025-09-10 09:29:36
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[IEEE 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Paris, France (2018.7.8-2018.7.13)] 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Bilateral Comparison LF Power Up to 100 kHz
摘要： Nowadays there is more need for traceability for distorted power waveforms. Therefore a power calibration system was developed at the European Standards Laboratory of Yokogawa Europe Solutions B.V. This system has the capability to calibrate electrical power meters from DC, 10 Hz up to 100 kHz. To evaluate the calibration system traceability, a bilateral comparison was carried out between the Yokogawa European Standards Laboratory and the National Standards Institute of Sweden (RISE).
关键词： Power system harmonics,Calibration,Uncertainty,Measurement,Power measurement
更新于2025-09-10 09:29:36
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[IEEE 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Paris, France (2018.7.8-2018.7.13)] 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Establishment of Reference Power Standard at SASO NMCC and GULFMET Bilateral Comparison
摘要： A well-known 3458A based digital sampling wattmeter was for power and harmonics measurements at SASO NMCC. Its compact design and synchronized to the power source makes the standard unique for the calibrations needed by nationwide laboratories and industry. 40 ppm and 200 ppm are the first estimations in measurement uncertainties for power and harmonics, respectively. And, the first power comparison was organized under GULFMET.EM-S2 in order to evaluate the performance of the standard.
关键词： bilateral comparison,Active power,harmonics,measurement uncertainty,calibration standard
更新于2025-09-10 09:29:36
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[IEEE 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Paris (2018.7.8-2018.7.13)] 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - ANIST Testbed for Examining the Accuracy of Smart Meters Under High Harmonic Waveform Loads
摘要： Household and industrial electrical energy measurements are advancing into a Smart Grid stage, using solid-state watt-hour meters, called smart meters. As electrical products are also becoming more based on solid-state designs, such as LED lighting and dimmers, electrical loads are not purely resistive, but contain voltage and current spikes. This paper describes a testbed laboratory that will attempt to model LED household lighting loads, and correlate the energy measurements for changes in accuracy by various kinds of smart meters under unusual loads.
关键词： power quality,smart watthour meters,power system harmonics,watthour meters,smart grid,power system measurements
更新于2025-09-10 09:29:36
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[IEEE 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Paris, France (2018.7.8-2018.7.13)] 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Step-Up Calibration of Resistive Voltage Dividers Using Two Sampling Digital Multimeters up to 50 kHz
摘要： A set of resistive voltage dividers was designed to be used in a measuring system of electric power up to 100 kHz. The calibration of the dividers based on the step-up method and a comparison system based on two Keysight-3458 digital multimeters working up to 50 kHz are described. This activity is part of a joint project of the National Metrology Institutes of Uruguay, Brazil and Argentina.
关键词： electric power,harmonics,wattmeter,measuring system,Voltage ratio
更新于2025-09-10 09:29:36
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[IEEE 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Paris, France (2018.7.8-2018.7.13)] 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Construction of New Shunts for a Wideband Sampling Wattmeter
摘要： This paper presents the status of the construction of current shunts from 20 mA to 100 A. They will be used as signal conditioners of a new standard for power measurements in the frequency range from 50 Hz to 100 kHz. The calibration in ratio is performed using ac-dc transfer difference while the phase calibration will be performed using a high-resolution, dual-channel digital sampling system.
关键词： electric power,Current shunts,harmonics,transducer,ac-dc transfer,phase displacement
更新于2025-09-10 09:29:36
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Evidence of depolarization and ellipticity of high harmonics driven by ultrashort bichromatic circularly?polarized fields
摘要： High harmonics generated by counter-rotating laser fields at the fundamental and second harmonic frequencies have raised important interest as a table-top source of circularly polarized ultrashort extreme-ultraviolet light. However, this emission has not yet been fully characterized: in particular it was assumed to be fully polarized, leading to an uncertainty on the effective harmonic ellipticity. Here we show, through simulations, that ultrashort driving fields and ultrafast medium ionization lead to a breaking of the dynamical symmetry of the interaction, and consequently to deviations from perfectly circular and fully polarized harmonics, already at the single-atom level. We perform the complete experimental characterization of the polarization state of high harmonics generated along that scheme, giving direct access to the ellipticity absolute value and sign, as well as the degree of polarization of individual harmonic orders. This study allows defining optimal generation conditions of fully circularly polarized harmonics for advanced studies of ultrafast dichroisms.
关键词： circularly polarized fields,high harmonics,ultrafast dichroisms,ultrashort pulses,polarization state
更新于2025-09-10 09:29:36
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Electron Cyclotron interaction in the early stage of EC-assisted plasma breakdown
摘要： Electron Cyclotron (EC) wave interaction with very low temperature electrons in conditions like those occurring for EC-assisted plasma breakdown is investigated via the Hamiltonian adiabatic formalism. Estimates of interest for applications to present tokamak experiments are derived. The analysis allows ultimately to derive analytically the particle energy gain per single beam crossing and to characterize the dependency of the maximum possible energy variation as a function of the wave frequency, harmonics and polarization and EC power and beam width. The investigation confirms that electrons can easily gain energies well above the ionization energy in most conditions, as observed in experiments.
关键词： tokamak experiments,beam width,Hamiltonian adiabatic formalism,harmonics,polarization,Electron Cyclotron,wave frequency,EC power,plasma breakdown
更新于2025-09-10 09:29:36
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Extremely low-profile second-order bandpass frequency selective surface using third harmonics of resonant elements
摘要： In high-order (N > 1) frequency selective surfaces (FSSs), the surfaces are usually cascaded vertically and separated by a dielectric substrate to achieve desired responses. The dielectric substrate thickness is a critical parameter in designing such structures. It is usually high for most traditional designs. In this article, we present a novel approach for designing extremely low-profile high-order bandpass FSSs. The structure is built by using the coupling of the third harmonics instead of the fundamentals of the resonators to achieve a bandpass response. By using the proposed design method, the coupling between the third harmonics can be very weak with a very thin substrate, and a flat response can be achieved. The thickness of the structure is reduced to one third in term of wavelength when compared with the structure using the fundamental mode. The overall thickness of a second-order FSS can be reduced to λ/75, where λ is the free space wavelength. A prototype of the proposed bandpass FSS is designed, fabricated, and experimentally characterized. The measurement results of this device show a very good and stable frequency response with respect to the angle of incidence up to (cid:1)45(cid:3) as predicted.
关键词： third harmonics,low profile,frequency selective surface,second order,Bandpass FSS
更新于2025-09-09 09:28:46
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POWER PERFORMANCE AND SPURIOUS FREQUENCIES ANALYSIS OF COMPOSITE RIGHT-/LEFT-HANDED (CRLH) DISTRIBUTED OSCILLATORS
摘要： This paper concerns the analysis of the performance of a Composite Right-/Left-Handed (CRLH) distributed oscillator. In order to increase its output power, a modification of the standard configuration is proposed. The basic idea is to combine the signals from the two output ports of the structure by means of a Wilkinson combiner, so obtaining a single output generator. The power performance of the conventional two output oscillator and the power performance of the new configuration are numerically compared by changing the number of employed transistors. The same procedure is adopted to analyze the amplitude of the higher order harmonics in the generated signals as a function of the number of active elements. On the basis of simulated data an increase of the output power, together with a second harmonic reduction, is expected for the single output oscillator with respect to the standard CRLH topology. Experimental results fully confirm these numerical predictions.
关键词： output power,Composite Right-/Left-Handed (CRLH),Wilkinson combiner,harmonics,distributed oscillator
更新于2025-09-09 09:28:46