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- 2018
- spectral irradiance
- correlated color temperature
- double monochromator
- color rendering index
- Uncertainty of measurement
- Measurement and Control Technology and Instruments
- Brno University of Technology
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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) - 10 TΩ and 100 TΩ Resistance Comparison Between NIST and AIST
摘要： We report the results of a comparison of 10 T? and 100 T? high resistance standards between the National Institute of Standards and Technology (NIST) and the National Institute for Advanced Industrial Science and Technology (AIST). Three standard resistors were hand carried between both laboratories, a 100 T? from NIST and a 10 T? and 100 T? from AIST. The two laboratories agreed to within 100 x 10-6 at 10 T? and 500 x 10-6 at 100 T?. The comparison results have given both laboratories an external check of their measurement systems and scaling processes to 100 T?.
关键词： dual source bridge,high resistance,uncertainty,voltage injection,standard resistor
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) - Null Technique for Precision RF Phase Shift Measurements
摘要： A dual channel IF substitution null system is developed for precision phase shift measurements and standards in frequency ranges of 1 MHz to 1 GHz. A particular programmable IF phase shifter equipped with a calibrated phase monitor is used as a phase reference standard. High sensitivity nature of the null technique provides accurate measurements to the DUT even with large attenuation. Measurement resolutions of 0.002 deg., 0.006 deg., and 0.023 deg. were obtained for DUT with attenuation of 20 dB, 40 dB, and 60 dB, respectively, at 1 GHz.
关键词： Phase measurement,uncertainty,radio frequency,precision measurements,attenuation measurement,phase shifters
更新于2025-09-10 09:29:36
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Finite Element Modellingand Simulations of Piezoelectric Actuators Responses with Uncertainty Quantification
摘要： Piezoelectric structures are widely used in engineering designs including sensors, actuators, and energy-harvesting devices. In this paper, we present the development of a three-dimensional finite element model for simulations of piezoelectric actuators and quantification of their responses under uncertain parameter inputs. The implementation of the finite element model is based on standard nodal approach extended for piezoelectric materials using three-dimensional tetrahedral and hexahedral elements. To account for electrical-mechanical coupling in piezoelectric materials, an additional degree of freedom for electrical potential is added to each node in those elements together with their usual mechanical displacement unknowns. The development was validated with analytical and experimental data for a range of problems from a single-layer piezoelectric beam to multiple layer beams in unimorph and bimorph arrangement. A more detailed analysis is conducted for a unimorph composite plate actuator with different design parameters. Uncertainty quantification was also performed to evaluate the sensitivity of the responses of the piezoelectric composite plate with an uncertain input of material properties. This sheds light on understanding the variations in reported responses of the device; at the same time, providing extra confidence to the numerical model.
关键词： finite element method,uncertainty quantification,piezoelectric materials,unimorph actuator,energy harvesting,PZT
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) - Calibration of AC Shunts at Frequencies Up to 10 kHz Using Digital Sampling
摘要： This paper describes a calibration system for AC shunts using digital sampling. It provides both ratio errors and phase displacements of a shunt under test with respect to a reference shunt. In its basic configuration, the calibration system operates at currents of up to 10 A and frequencies of up to 10 kHz. The expanded uncertainties (k = 2) of the described calibration system are estimated to be better than 30 μA/A for magnitude and 30 μrad for phase at 10 kHz, and lower than these at lower frequencies.
关键词： calibration,calculable resistor,current comparator,current measurement,measurement uncertainty,AC shunt,measurement standards
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) - Current Divider Based Impedance Comparator
摘要： The paper describes an ac impedance measurement comparator system which uses a current divider (or splitter). The divider makes use of a current comparator whose windings are connected in a way such as to allow the splitting of a single current signal in two components with very accurate ratio to be attained. Each current component flows through impedances to be compared. Preliminary investigations indicate that such an arrangement is able to provide very accurate impedance measurements with errors of parts in 106 or even smaller. Resolutions of parts in 109 were also experimentally achieved. Since the system uses a single ac current source, inherent current instabilities of the source cause negligible effects on differential voltage measurements, what alleviates requirements on the ac source. Digital sampling can easily be implemented with the system for speeded-up and automated impedance comparisons.
关键词： Circuit and systems,current measurement,Hall effect devices,measurement uncertainty,measurement techniques,impedance measurement,electronic circuits,electrical resistance
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) - Progress on the New NMIA Calculable Cross-Capacitor
摘要： A new calculable cross-capacitor and associated impedance measurement chain is being built at the National Measurement Institute Australia (NMIA). The new system is intended to reduce the uncertainty of the farad as realised by a calculable capacitor to a few parts in 109, an order of magnitude improvement on existing calculable capacitor systems. We report here on recent progress on the assembly of the calculable capacitor, specifically the measurement of the frequency dependent correction, and the final alignment of the electrodes.
关键词： precision measurements,measurement uncertainty,measurement standards,Capacitance
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) - Electron Paramagnetic Resonance Study on a 28Si Single Crystal for the Future Realization of the Kilogram
摘要： In the future realization of the kilogram using the x-ray crystal density method, isotopically enriched silicon crystals grown by the floating zone method are employed. In this paper, we present the electron paramagnetic resonance study on 28Si single crystal AVO28. We revealed that the concentrations of various kinds of vacancy defects in the crystal are less than 1 × 1012 cm–3. Consequently, the necessary mass deficit correction due to these vacancy defects is estimated to be less than 0.4 μg for 1 kg AVO28 spheres.
关键词： electron paramagnetic resonance,silicon crystal,measurement uncertainty,kilogram,vacancy defects
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) - Optical Frequency Measurements at 1×10?18 Uncertainty with Ytterbium Optical Lattice Clocks
摘要： We describe ytterbium optical lattice clocks under development at NIST. This includes the characterization of optical frequency stability and uncertainty, as well as measurements between two independent clocks, at the 10-18 level. We also report on optical frequency ratio measurements with other optical clocks at NIST.
关键词： precision frequency,optical lattice,optical standard,ytterbium,frequency measurement,uncertainty,optical ratio,optical clock
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) - A Synchronized Current-Comparator-Based Power Bridge for Calibrating Analog Merging Units
摘要： A synchronized current-comparator-based power bridge for calibrating analog merging units at power frequencies of 60 Hz and 50 Hz is described. Analog merging units take analog signals from instrument transformers, convert them into digital form, pack the sampled values into Ethernet frames conforming to the IEC 61850-9-2 LE specification and stream the frames to other equipment in a digital substation for further processing. Since the sampled values are used for protection and metering, the merging units need to be calibrated. The expanded uncertainties (k=2) of the described calibration system are estimated to be better than 30 μA/A for magnitude and 60 μrad for phase.
关键词： calibration,current comparator,measurement uncertainty,Instrument transformers,power bridge,merging unit
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) - Calibration Factor Measurement up to 50 GHz at TüB?TAK UME
摘要： TüB?TAK UME has established a new power sensor calibration setup incorporating a monitor power sensor utilizing the direct comparison transfer method for frequencies up to 50 GHz. The system adds to TüB?TAK UME’s existing capability to measure power sensors with type N and 3.5 mm connectors. The new measurement setup was validated using certificate values of power sensors for each working frequency range. Good agreement was found between previous calibration results and those obtained with the new system.
关键词： power sensor,microwave power,uncertainty,microwave measurements,Calibration factor
更新于2025-09-10 09:29:36