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Search Publications by: Weston L. Tew (Fed)

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Displaying 1 - 25 of 74

Harmonic dependence of thermal magnetic particle imaging

September 22, 2023
Author(s)
Thinh Bui, Mark-Alexander Henn, Weston L. Tew, Megan Catterton, Solomon I. Woods
Advances in instrumentation and tracer materials are still required to enable sensitive and accurate 3D temperature monitoring by magnetic particle imaging. We have developed a magnetic particle imaging instrument to observe temperature variations using

ITS10 Conference Digest

April 18, 2023
Author(s)
Christopher W. Meyer, Kathryn Miller, Weston L. Tew, Howard W. Yoon
The 10th International Temperature Symposium (ITS10) was held in Anaheim California on April 3rd to 7th, 2023. More than 180 abstracts were received and accepted and 159 of those were presented at the symposium. This document is a record of the symposium

Parallel MPI image reconstructions in GPU using CUDA

March 19, 2023
Author(s)
Klaus Natorf Quelhas, Mark-Alexander Henn, Ricardo Cordeiro de Farias, Weston L. Tew, Solomon I. Woods
This work shows that it is possible to obtain faster MPI image reconstructions by implementing the algorithms in parallel in Graphics Processing Units (GPUs) using NVIDIA's CUDA (Compute Unified Device Architecture). While the parallel Kaczmarz's algorithm

2022 Update for the Differences Between Thermodynamic Temperature and ITS 90 Below 335 K

December 27, 2022
Author(s)
Christof Gaiser, Bernd Fellmuth, Roberto Maria Gavioso, Murat Kalemci, Vladimir Kytin, Tohru Nakano, Laurent Pitre, Anatoli Pokhodun, Patrick Rourke, Richard Rusby, Peter P.M. Steur, Weston L. Tew, Robin James Underwood, Rod White, Inseok Yang, Jintao Zhang
In 2011, a working group of the Consultative Committee for Thermometry published best estimates of the differences between thermodynamic temperature (T) and the International Temperature Scale ITS 90 (T90). But for temperatures below 335 K, it was stated

Flexible Software for Rigorous Simulations of Magnetic Particle Imaging Systems

March 21, 2022
Author(s)
Klaus Natorf Quelhas, Mark-Alexander Henn, Thinh Bui, Hunter Wages, Weston L. Tew, Solomon I. Woods
Modeling of Magnetic Particle Imaging (MPI) systems allows for developing and testing novel methods for image reconstruction and simulating various setups without the need of real-life measurement data. Here we describe the the initial development of a C++

Guide on Secondary Thermometry: Industrial Platinum Resistance Thermometers

January 18, 2022
Author(s)
Jonathan Pearce, Richard Rusby, Kazuaki Yamazawa, Stefan Rudtsch, L Iacomini, Giuseppina Lopardo, D Rodney White, Weston L. Tew
This document is a part of guidelines, prepared by the Consultative Committee for Thermometry, on the techniques for approximating the International Temperature Scale of 1990. It collates information on industrial platinum resistance thermometry. The

Advanced characterization of magnetization dynamics in iron oxide magnetic nanoparticle tracers

January 5, 2022
Author(s)
Thinh Bui, Adam Biacchi, Brianna Bosch Correa, Cindi L. Dennis, Weston L. Tew, Angela R. Hight Walker, Solomon I. Woods
Characterization of the magnetization dynamics of single-domain magnetic nanoparticles (MNPs) is important for magnetic particle imaging (MPI), magnetic resonance imaging (MRI), and emerging medical diagnostic/therapeutic technologies. Depending on

Johnson Noise Thermometry

September 3, 2019
Author(s)
Weston L. Tew, Jifeng Qu, K L. Zhou, Samuel P. Benz, Horst Rogalla, David R. White
Johnson noise thermometers infer thermodynamic temperature from measurements of the thermally-induced current fluctuations that occur in all electrical conductors. This paper reviews the status of Johnson noise thermometry and its prospects for both

The NIST Johnson noise thermometry system for the determination of the Boltzmann constant

December 29, 2017
Author(s)
Nathan Flowers-Jacobs, Alessio Pollarolo, Kevin Coakley, Adam C. Weis, Anna Fox, Horst Rogalla, Weston L. Tew, Samuel Benz
In preparation for the redefinition of the International System of Units (SI), five different electronic measurements of the Boltzmann constant have been performed using different Johnson noise thermometry (JNT) systems over the past seven years. In this

A Boltzmann Constant Determination Based on Johnson Noise Thermometry

August 10, 2017
Author(s)
Nathan E. Flowers-Jacobs, Alessio Pollarolo, Kevin J. Coakley, Anna E. Fox, Horst Rogalla, Weston L. Tew, Samuel P. Benz
A value for the Boltzmann constant was measured electronically using an improved version of the Johnson Noise Thermometry (JNT) system at the National Institute of Standards and Technology (NIST), USA. This system is different from prior ones, including

An improved electronic measurement of the Boltzmann constant by Johnson noise thermometry

July 18, 2017
Author(s)
Jifeng Qu, Samuel Benz, Kevin Coakley, Horst Rogalla, Weston L. Tew, David R. White, Kunli Zhou, Zhenyu Zhou
Recent measurements using acoustic gas thermometry have determined the value of the Boltzmann constant, k, with a relative uncertainty less than 110-6. These results have been supported by a measurement with a relative uncertainty of 1.910-6 made with

Improved spectra aberration in the Johnson Noise Thermometry

July 9, 2016
Author(s)
Alessio Pollarolo, Horst Rogalla, Anna Fox, Kevin J. Coakley, Weston L. Tew, Samuel P. Benz
SPECTRAL ABERRATION HAS BEEN FOR A LONG TIME THE MAIN SOURCE OF UNCERTAINTY IN THE JOHNSON NOISE THERMOMETRY APPROACH TO MEASURING THE BOLTZMANN CONSTANT. RECENTLY, WITH NEWLY DEVELOPED HARDWARE AND THE INTRODUCTION OF A NOVEL FITTING ALGORITHM FOR

SRM 1967a: High-Purity Platinum Thermoelement

March 9, 2016
Author(s)
Karen M. Garrity, Weston L. Tew, Dean C. Ripple
Consisting of a 1 m long piece of 0.5 mm diameter platinum wire, SRM 1967a meets the requirements for a thermoelectric reference material for temperatures from 196 °C up to approximately 1700 °C. We have tested the thermoelectric emf of four SRM 1967a

Advances in Thermometry

January 1, 2016
Author(s)
Michael R. Moldover, Weston L. Tew, Howard W. Yoon
The last 25 years have seen tremendous progress in thermometry in the moderate temperature range (1 K to 1235 K). Various primary thermometers — based on different physics —have uncovered errors in the International Temperature Scale of 1990 and set the

Improved electronic measurement of the Boltzmann constant by Johnson noise Thermometry

August 19, 2015
Author(s)
Weston L. Tew, Samuel P. Benz, Horst Rogalla, Alessio Pollarolo, David R. White, Jifeng Qu, Kunli Zhou
The unit of thermodynamic temperature, the kelvin, will be redefined in 2018 by fixing the value of the Boltzmann constant, k. The present CODATA recommended value of k is determined predominantly by acoustic gas-thermometry results. To provide a value of

Calibration of thin-film platinum sensors for use in the JILA Sr II Clock

March 29, 2015
Author(s)
Weston L. Tew, Travis L. Nicholson, Ross B. Hutson
A set two pairs of thin-film platinum resistance thermometers (TFPRTs) have been calibrated on the International Temperature Scale of 1990 (ITS-90) for the purposes of determining temperatures inside the JILA Sr II Optical Lattice Clock vacuum chamber. The

Systematic Error Resolved in NIST Johnson Noise Thermometer

August 24, 2014
Author(s)
Alessio Pollarolo, Weston L. Tew, Horst Rogalla, Samuel P. Benz
In the Johnson Noise Thermometry approach, Boltzmann’s constant k is obtained as the ratio of the noise power measured across a sense resistor at the triple point of water and the noise power measured for a synthesized reference waveform. The reference

Improvements to the Johnson Noise Thermometry System for Measurements at 505 – 800 K

September 12, 2013
Author(s)
Weston L. Tew, Kazuaki Yamazawa, Samuel P. Benz, Alessio Pollarolo, Horst Rogalla, Paul D. Dresselhaus
The National Institute of Standards and Technology (NIST) is currently using Johnson noise thermometry (JNT) to determine the deviations of the International Temperature Scale of 1990 (ITS-90) from the thermodynamic temperature in the range of 505–933 K