A5085012128- Scientific Measurement and Uncertainty Evaluation
- Sensor Technology and Measurement Systems
- Advanced Electrical Measurement Techniques
- Advanced Sensor Technologies Research
- Radioactive Decay and Measurement Techniques
- Magnetic Field Sensors Techniques
- Advanced Measurement and Metrology Techniques
- Quantum and electron transport phenomena
- Advanced Frequency and Time Standards
- Non-Destructive Testing Techniques
- Advancements in Semiconductor Devices and Circuit Design
- Physics of Superconductivity and Magnetism
- Atomic and Subatomic Physics Research
- Analytical Chemistry and Sensors
- Magneto-Optical Properties and Applications
- Particle accelerators and beam dynamics
- Electromagnetic Launch and Propulsion Technology
- Power Transformer Diagnostics and Insulation
- Power Quality and Harmonics
- Surface and Thin Film Phenomena
- Advanced MEMS and NEMS Technologies
- Seismic Waves and Analysis
- Experimental and Theoretical Physics Studies
- Flow Measurement and Analysis
- Superconducting and THz Device Technology
National Institute of Metrology
2014-2025
Beijing Academy of Quantum Information Sciences
2016-2024
Beijing University of Chemical Technology
2023
General Administration of Quality Supervision, Inspection and Quarantine
2016-2019
Northridge Hospital Medical Center
2018
Harbin Institute of Technology
2012-2016
The traditional polyolefin separators used in lithium-ion batteries (LIBs) are plagued by limitations such as poor wetting of electrolytes and insufficient thermal stability, hindering the progress LIBs. To overcome these limitations, we have developed a modified phase inversion technique to efficiently durably coat with poly(ether ether ketone) (PEEK). resulting PEEK-coated exhibit mechanical properties similar those unmodified separators, comparable tensile strength modulus. Furthermore,...
Permanent magnet synchronous motor (PMSM) has been widely employed in the continuous-wave pulse generator and exhibits advanced performance. However, its applications are constrained to some extent, because of alternating load shocks measurement resolution, etc. To cope with these issues, a double degree-of-freedom (DOF) control strategy that combines extended Kalman filter (EKF) adaptive linear active disturbance rejection (LADRC) is proposed realize fast dynamic response strong...
The National Institute of Metrology (NIM, China) proposed a joule balance method to measure the Planck constant in 2006, and built first prototype NIM-1 verify its principle with relative uncertainty 8.9 × 10–6 by 2013. Since 2013, new NIM-2 has been designed, series improvements reduce measurement uncertainty. By April 2017, constructed can be employed vacuum. A on yields determination is 6.626 069 2(16) 10–34 Js 2.4 10–7. differs terms −1.27 10–7 from CODATA 2014 value. Further improvement...
The joule balance experiment has been carried out at the National Institute of Metrology, China (NIM) since 2007. By end 2013 first generation (NIM-1) achieved a measurement uncertainty 7.2 × 10−6 (k = 1). To reduce further, next apparatus (NIM-2) system is under construction. A new coil using ferromagnetic material being adopted in NIM-2 to self-heating coils. However, effects on mutual inductance from nonlinearity and hysteresis will bring considerable uncertainty. Inspired by watt...
Main text This report describes the second CCM key comparison of realizations kilogram definition based on fixed numerical value Planck constant, which came into force 20 May 2019. The objectives were to determine level agreement between using Kibble and joule balances x-ray crystal density (XRCD) method provide input for calculation "consensus value" kilogram. consensus serves as basis an internationally coordinated dissemination is updated after each new comparison. Its use will continue...
A self-calibration method is proposed for determining the current ratio DC devices. To demonstrate feasibility of proposal, an experimental test with nominal ratios 10:1 100:1 and 1000:1 performed, a three-step calibration procedure used: Firstly, eleven magnetic modulator-based transducers (DCCTs) are used to realize through reference method; secondly, DCCTs series-parallel achieve build-up from 100:1; finally, another DCCT auxiliary calibration, combining two steps before. The merit that...
A precision resistance measurement method based on synchronous sampling is proposed to enable accurate under low-current testing conditions. This utilizes a single current source input, connecting the standard resistor and test in series. The setup simple, easy operate, allows for convenient rapid comparison of voltage across resistors. value determined through calculation, achieving high accuracy. An experimental two resistors low 1 μA demonstrated that data dispersion reached 10−6 level,...
The precise measurement of Planck constant <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$h$</tex></formula> to establish a kind quantum mass standard is an important but very difficult work. Joule Balance method, for the same purpose different from Watt has been going on at National Institute Metrology three years. All measurements were carried out in atmosphere air-conditioned room. uncertainty...
A capacitive sensor is proposed to measure the departure from vertical movement. It has a special structure consisting of long silica filament static plate and cylindrical-surface moving plate. Now it adopted horizontal displacement movable coil along direction in joule balance. For consideration avoiding error caused by transfer process reference, designed have direct reference. The measurement errors imperfection plates are discussed. In addition, characteristics sensor, such as...
A quasi-digital dc current sensor with rated of ±600 while overload about ±750 is proposed in this paper. The new based on the open-loop self-oscillating fluxgate technology, but its originality using a microcontroller unit to detect duty cycle exciting voltage fluxgate. Compared published similar method, whole signal chain and without low-pass filter analog-to-digital converter required when connected digital systems. precisely theoretical equation respect linear dependence between be...
Precision measurement of dc high current is usually realized by second harmonic fluxgate transducers, but the complicated modulation and demodulation circuits with cost have been limiting their applications. This paper presents a low-cost transducer that can substitute traditional ones for precision current. The new transducer, based on principle zero-flux, combination an improved self-oscillating sensor magnetic integrator in common feedback loop. transfer function zero-flux control...
This report describes the first CCM key comparison of realizations kilogram definition based on fixed numerical value Planck constant, which came into force 20 May 2019. The objectives were to determine level agreement between using Kibble and joule balances X-ray crystal density (XRCD) method provide input for calculation "consensus value" kilogram. consensus will serve as basis an internationally coordinated dissemination continue until sufficient realization experiments has been achieved....
In the joule balance developed at National Institute of Metrology, dynamic phase a watt is replaced by mutual inductance measurement in an attempt to provide alternative method for kilogram redefinition. However, this rather large current exciting coil, needed offer necessary magnetic field force weighing phase, and coil heating becomes important uncertainty source. To reduce heating, new system, which ferromagnetic material used increase was designed recently. adopting brings difficulty...
A system based on laser heterodyne interferometer is proposed in this paper to measure and control the movable coil position of a joule balance. damping used suppress movement horizontal direction while piezoelectric ceramic unit with PID controller inhibit vibration long term drift vertical direction. The effectiveness method measuring controlling balance proved through experiments. Experimental results indicate that displacement can be reduced from 400 50 nm its successfully inhibited.
A simple differential capacitive sensor is provided in this paper to measure the absolute positions of length measuring systems. By utilizing a shield window inside capacitor, measurement range and linearity can reach several millimeters. What more interesting that only sensitive one translational degree freedom (DOF) movement, immune vibration along other two DOFs. In experiment, we used novel circuit based on an AC capacitance bridge directly value. The experimental result shows has...
A six-axis heterodyne interferometer system has been designed for the joule balance to measure relative displacement between suspended coil and exciting coil. The essential optical components in this are three dual-axis interferometers. Each can simultaneously displacements of one retro-reflector (RR) on RR Because common path structure, is susceptible periodic nonlinearity caused by double-frequency mixing. However, a method be used eliminate errors. measured strictly locked integral...
Since beginning the construction early in 2005, considerable progress has been made on watt balance of Bureau International des Poids et Mesures (BIPM). We have continued development a room-temperature version to test feasibility simultaneous force and velocity measurements. Preliminary measurements voltage-velocity ratio carried out with reproducibility order 1 part 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sup> . The coil...
The precise dc-based measurement of the mutual inductance is one key issues in Joule Balance method used to determine Planck's constant <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">h</i> . Here, a new compensation with standard square wave provided. dc value obtained by measuring integral area induced voltage. To increase accuracy this method, we just accurately measure residual observed between voltage inductor and synchronously generated...
A new type of calculable capacitor was initially built at the National Institute Metrology, China, in cooperation with Measurement Institute, Australia. The realized SI unit capacitance 1 pF, an uncertainty 20 parts <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$10^{9}$ </tex-math></inline-formula> . simplified operational approach used that avoids complex substitution measuring process small-value...
The International Bureau of Weights and Measures (BIPM) is developing a watt balance for the forthcoming redefinition kilogram. An improved version apparatus, based on new closed magnetic circuit now being assembled. apparatus will significantly reduce type B uncertainty due to misalignment as this work demonstrates. We present two techniques recently developed accurately align field perpendicular direction defined by local acceleration gravity. Uncertainty below 30 μrad was achieved both...
As an important part of the joule balance system, two-axis elliptical notch flexure hinge (TENFH) which typically consists two single-axis hinges was studied. First, a 6 degrees freedom (6-DOF) compliance model established based on coordinate transformation method. In addition, maximum stress TENFH derived. The and verified using finite element analysis simulation. To decouple attitude suspended coil system reduce offset between centroid mechanism mass comparator in new mechanical structure...
The development of the joule balance method to measure Planck constant, in support redefinition kilogram, has been going on at National Institute Metrology China (NIM) since 2007. first prototype built check feasibility principle. In 2011, relative uncertainty constant measurement NIM is 7.7 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-5</sup> . Self-heating and swing coils are main contributions. Since 2012, some improvements have made...