We present a resonant Rydberg electric field s ensor o perating i n t he UHF band using a dual-optical-dual-microwave spectroscopy scheme. We measure Sirius XM satellite radio, and compare the sensitivity to other contemporary implementations of the technology.
We describe our progress toward a system to calibrate electrometers that measure currents from ionization chambers. The calibration system uses a 1 GΩ standard resistor in series with a stable voltage source to generate calibration currents from 1 pA to 20 nA, traceable to quantum voltage and resistance standards through an 8-1/2 digit digital multimeter and the standard resistor. Expanded uncertainties ( k=2) of 100×10 -6 or better for the calibration of the electrometer are needed for the ionization chamber measurements. We show our preliminary results including our initial calibration correction.
A novel four-terminal pair impedance bridge combined with a quantum Hall resistor will be presented. The impedance bridge is based on pulse-driven Josephson arrays. A very simple setup is possible due to the triple-series connection of the quantum Hall resistor that renders combining networks superfluous. This combination of the two well-known macroscopic quantum effects presents a unique possibility for the realization of electrical units. Moreover, the Josephson bridge can be used to precisely investigate the plateau shape of quantum Hall devices in the AC regime.
Magnetic flux leakage (MFL) testing is a commonly used technique for detecting and estimating the defect in ferromagnetic materials. The lift-off value has a great influence on the detected MFL signal which need more attention to study its impact. In this paper, the relationship between the MFL signal and the lift-off value has been analyzed based on the property of MFL signal. A simplified calculation model of MFL signal of defect has also been established here. To verify the proposed calculation model, a MFL testing of defect in a ferromagnetic pipeline has been conducted and the experiment result shows the well performance for the proposed model.
Defect edge detection (DED) is a fundamental issue in magnetic flux leakage (MFL) testing, while the traditional DED methods are not precise enough. The paper analyzes the errors of traditional DED methods. Furthermore, the approximation characteristic of the MFL signal is proposed and the paper develops a characteristic approximation approach (CAA) to detect the defect edge. Compared with traditional DED methods, CAA improves the edge recognition accuracy from 6 % to 0.99 %, which can facilitate the defect sizing in MFL testing.
In this paper, a portable standard is proposed for allowing online PMU calibrations without service interruption. This system is connected in parallel with the under test PMU, using current and voltage sensors that do not need any disconnection of the PMU.
We have measured the temperature dependent Fresnel reflection loss and Rayleigh backscatter of SMF-28 fibre, polarisation maintaining (PM) single-mode fibre and solid core high index PM photonic crystal fibre (PCF). We show that the effective refractive index N-eff of these fibres reduces by 0.11 %, 0.15 % and 0.30 % respectively from room temperature to 5 K. This relates to an increase in fibre output power of 0.02 %, 0.03 % and 0.06 %. The Rayleigh backscatter is shown to increase 15x for the standard single mode fibre, and 4x for the photonic crystal fibre at low temperature. We have quantified these changes in order to apply a correction to our fibre-coupled primary standard cryogenic radiometer for optical fibre power measurements. We use an in-situ beam-splitter measurement technique to measure the Fresnel reflection at 1310 nm and 1550 nm and we confirm the results at 1550 nm with an optical frequency domain reflectometer measurement.
This paper summarizes the various improvements to and measurements carried out with the BIPM Kibble balance for realizing the definition of the mass unit in terms of the Planck constant. Measurement uncertainty has been significantly reduced by a factor of four. Mass measurement of a 1 kg Pt/Ir artefact was carried out during three periods in 2019. The mass of the artefact was measured in vacuum with a standard uncertainty of about 50 μg. Efforts are underway to further reduce measurement uncertainty which is dominated by the misalignment and the electrical measurements.
The article presents a root mean square (RMS) to direct current (dc) converter based on an externally linear-internally nonlinear (ELIN) filter. The converter contains an averaging filter and two nonlinear blocks. The principle of operation of an ELIN circuit using an example of the ELIN integrator was presented. Three converters were developed and simulated each using four multiplier/divider integrated circuits. Preliminary tests of the input dynamic range of the three circuits were made by SPICE simulations. The prototype of the RMS-todc converter with a third-degree ELIN filter shows an improved dynamic range in comparison to classic "implicit square-rooting" converters as its error is reduced at lower amplitudes of the input voltage. The measured bandwidth of the ELIN converter prototype is wider in comparison to the "implicit square-rooting" converter prototype, built from nominally the same nonlinear components. The converter based on the presented circuit can be used in applications, where a wide voltage range and wide bandwidth are needed.
This paper describes an automation software platform for determining the bandwidth of keysight 3458A digital multimeter up to 200 kHz. Two 3458As can be tested simultaneously for different ranges from 0.1 V to 1000 V. The platform is implemented using a commercial function generator for frequency-amplitude characteristics measurement. Results show that the bandwidths between 3458As are slightly instrument dependent when operating in the DCV mode. A large deviation from the specification of the manual is observed for the 10 V range. The amplitude-frequency characteristic is approximated using 1(st) and 2(nd)-order least mean-square fitting algorithm. The result is proved to give rise to large uncertainties at the frequency band up 10 kHz.
This paper firstly briefly presents the JAWS system established in TÜBİTAK UME and the Sampling System already used in previous comparisons. Then sampling conditions used for sampling the JAWS output and algorithm used for estimating the measurement results are described. Measurement results show that the sampling system is able to measure AC voltages up to 500 Hz more accurately than the established AC voltage metrology at small AC Voltages.
The paper describes a digital low-frequency ac voltage source with amplitude stability better than 10 -6 V/V per hour. It was developed to be used as a transfer standard for calibrations with ac Josephson systems and fast synchronous ac-dc transfer measurements. Its low-distortion and superb phase adjustment resolution makes it suitable for impedance measurements as well.
Capacitance and AC resistance comparisons at audio frequencies are being performed by using a four-terminal pair transformer-based coaxial AC bridge at TÜBİTAK UME. A four-terminal pair digitally assisted (DA) coaxial AC bridge has been developed in order to reduce the complexity of coaxial transformer AC bridges. This paper describes realization of four-terminal pair DA coaxial AC bridge using commercial DAQ modules and performance test measurements by using the transformer-based bridge. According to preliminary results, the bridge can be balanced automatically in less than 5 minutes. R-R and C-C comparisons at 1 kHz and 10 kΩ magnitude level give ratio errors of a few 10 -6 . Further improvements for ratio errors and bridge balancing time will be performed.
The measurement of inner local thinning wall is necessary for the ferromagnetic structures. This paper proposed a novel method to estimate the reduced thickness based on the reluctance of the simplified magnetic circuit model. The simulation results agree well with the mathematical model, which means we can evaluate the reduced thickness accurately under the premise of knowing the size of the thinned section. The simple principle allows the sensor to be miniaturized. All results show that this method has great promise in practical practice.
This paper describes a current-controlled voltage source for simulation of Josephson junction arrays. The I-V characteristics of different Josephson junction arrays are simulated using a micro-controller, which can then calculate and generate an expected voltage according to input parameters including the number of junctions, microwave frequency and power, etc. This simulator can serve as an educational tool; it can also help reduce development costs of various PJVS applications.
So far, an accurate and applicable harmonic phasor estimator for power system monitoring is still missing. To address this problem, this paper proposes a harmonic phasor estimator based on the frequency-domain sampling theorem. Dynamic harmonic phasors are modeled by complex exponential functions. Simulation tests show that the proposed method is more accurate and more applicable than the sinc interpolation functions-based algorithm. A theoretical analysis is also presented to discuss the harmonic phasor estimation errors under ideal conditions.
As a kind of nondestructive testing (NDT) method, shear-horizontal (SH)-guided wave detection technology is widely used on an electromagnetic acoustic transducer (EMAT). Although ultrasonic-guided waves perform well in defect location, it is difficult to obtain detailed information about defects, and the low efficiency of EMAT energy conversion still reduces the EMAT’s performance. Therefore, in this work, the defect detection method of different shapes and sizes by point-focusing shear-horizontal (PFSH)-guided wave EMAT with the use of periodic permanent magnet (PPM) is investigated through simulation and experiment. For the purpose of defect classification and quantification, the extraction principles of defect features are obtained through simulation based on the circumferential scatter diagrams, and the neural network (NN) is used to process the features extracted from the experimental data. The results show that by extracting effective defect features from the scatter diagram, high-accuracy classification and high-precision quantification of defects under the influence of the focusing transducer can be achieved.
A preliminary study suggests that the one-mode one measurement phase (OMOP) scheme may be feasible in the joule balance because of its quasi-static measurement feature. Combined with the recent research conclusion on the magnetization effect in the joule balance with compensation coil, two necessary hardware improvements to enable the OMOP joule balance are analyzed in this paper. Furthermore, a key parameter that can affect the statistical uncertainty of the final mass measurement result is experimentally determined.
An AC-current-ratio comparison was performed in order to compare the measurement capabilities of NMI's in the Inter-American Metrology System (SIM), in the field of calibration of instrument current transformers, and link it with the European round of EURAMET through PTB. This paper shows preliminary results.
