scholarly journals Improving fixed-point cell realization by modifying furnace heater shape

2019 ◽  
Author(s):  
Dave Lowe ◽  
Louise Wright ◽  
Chris Liller
Keyword(s):  
Fixed Point ◽  
High Temperature ◽  
Fixed Points ◽  
Temperature Scale ◽  
Melting Range ◽  
Furnace Temperature ◽  
Run Off ◽  
Cell Position ◽  
High Temperature Fixed Points ◽  
Set Up

Recent changes to the SI make it possible to set up a primary temperature scale using established values for certain high-temperature fixed points. As the furnace used with the fixed points can itself have a significant impact on measurements, improving furnace temperature uniformity can help to reduce uncertainties. A thermal model was used to redesign heaters to reduce temperature gradients where the fixed-point cell is positioned in the furnace. A heater optimised for 1325 °C was compared to the standard one with a cobalt carbon high-temperature fixed-point cells, where the cell was installed in the middle, and also moved 10 mm to each end. The modified heater showed reduced melting range, improved plateau run-off and less sensitivity to fixed-point cell position. The improvements will reduce the uncertainties associated with this type of furnace.

New fixed point of on-orbit calibration scale based on the In-Bi eutectic alloy for application in novel high-stable space-borne standard sources

2021 ◽  
pp. 32-37
Author(s):  
Andrei A. Burdakin ◽  
Valerii R. Gavrilov ◽  
Ekaterina A. Us ◽  
Vitalii S. Bormashov
Keyword(s):  
Phase Transition ◽  
Fixed Point ◽  
Fixed Points ◽  
Eutectic Alloy ◽  
Earth Observation ◽  
Melt Temperature ◽  
Phase Transition Temperatures ◽  
Set Up ◽  
The Stability ◽  
Observation Space

The problem of ensuring stability of Earth observation space-borne instruments undertaking long-term temperature measurements within thermal IR spectral range is described. For in-flight reliable control of the space-borne IR instruments characteristics the stability of onboard reference sources should be improved. The function of these high-stable sources will be executed by novel onboard blackbodies, incorporating the melt↔freeze phase transition phenomenon, currently being developed. As a part of these works the task of realizing an on-orbit calibration scale within the dynamic temperature range of Earth observation systems 210−350 K based on fixed-point phase transition temperatures of a number of potentially suitable substances is advanced. The corresponding series of the onboard reference blackbodies will be set up on the basis of the on-orbit calibration scale fixed points. It is shown that the achievement of the target lies in carrying out a number of in-flight experiments with the selected fixed points and the prospective onboard fixed-point blackbodies prototypes. The new In-Bi eutectic alloy melt temperature fixed point (~345 K) is proposed as the significant fixed points of the future on-orbit calibration scale. The results of the new fixed point preliminary laboratory studies have been analyzed. The results allowed to start preparation of the in-flight experiments investigating the In-Bi alloy for the purpose of its application in the novel onboard reference sources.

T 90 Measurement of Co-C, Pt-C, and Re-C High-Temperature Fixed Points at the NIM

2011 ◽  
Vol 32 (7-8) ◽  
pp. 1744-1752 ◽  
Author(s):  
Z. Yuan ◽  
T. Wang ◽  
X. Lu ◽  
W. Dong ◽  
C. Bai ◽  
...  
Keyword(s):  
High Temperature ◽  
Fixed Points ◽  
Temperature Fixed Points ◽  
High Temperature Fixed Points

Stability of cobalt–carbon high temperature fixed points doped with iron and platinum

Metrologia ◽  
2015 ◽  
Vol 52 (2) ◽  
pp. 353-359 ◽  
Author(s):  
L Kňazovická ◽  
D Lowe ◽  
G Machin ◽  
H Davies ◽  
A Rani
Keyword(s):  
High Temperature ◽  
Fixed Points ◽  
Temperature Fixed Points ◽  
High Temperature Fixed Points

scholarly journals LONG-TERM STABILITY OF Co-C AND Pd-C EUTECTIC FIXED POINTS FOR THERMOCOUPLES CALIBRATION

2021 ◽  
Vol 82 (1) ◽  
pp. 26-29
Author(s):  
Yasser A. Abdelaziz ◽  
◽  
F.M. Megahed ◽  
M. M. Abdel-Aal ◽  
◽  
...  
Keyword(s):  
Fixed Point ◽  
Fixed Points ◽  
Temperature Scale ◽  
Term Stability ◽  
Long Term Stability ◽  
International Temperature Scale ◽  
Definition Of The Kelvin ◽  
Definition Of ◽  
Eutectic Fixed Points

Eutectic fixed points are close to becoming a reference for high temperatures calibration, especially as the new International Temperature Scale (ITS) approach to issue after the re-definition of the Kelvin unit. In this work the long-term stability of Co-C and Pd-C eutectic fixed points were investigated using NIS-Egypt facilities. The eutectic points were measured using Pt/Pd thermocouple. The total exposure to the Co-C and Pd-C melting temperature was about 200 h for the fixed-point cell and 150 h for the Pt/Pd thermocouple. The emfs of the thermocouple at the melting point were observed to drift by about 0.25 °C. Realization uncertainties were estimated to be ~ 0.446 ◦C for Co-C and ~0.742 for Pd-C (k = 2). Results show that Co-C and Pd-C eutectic cells can exhibit long term stability.

scholarly journals Asymptotically Safe Gravity-Fermion Systems on Curved Backgrounds

Universe ◽  
2021 ◽  
Vol 7 (8) ◽  
pp. 306
Author(s):  
Jesse Daas ◽  
Wouter Oosters ◽  
Frank Saueressig ◽  
Jian Wang
Keyword(s):  
Fixed Point ◽  
Fixed Points ◽  
Chiral Symmetry ◽  
Chiral Symmetry Breaking ◽  
Background Field ◽  
High Energy ◽  
Dirac Fermions ◽  
Dynamical Mechanism ◽  
Asymptotic Safety ◽  
Set Up

We set up a consistent background field formalism for studying the renormalization group (RG) flow of gravity coupled to Nf Dirac fermions on maximally symmetric backgrounds. Based on Wetterich’s equation, we perform a detailed study of the resulting fixed point structure in a projection including the Einstein–Hilbert action, the fermion anomalous dimension, and a specific coupling of the fermion bilinears to the spacetime curvature. The latter constitutes a mass-type term that breaks chiral symmetry explicitly. Our analysis identified two infinite families of interacting RG fixed points, which are viable candidates to provide a high-energy completion through the asymptotic safety mechanism. The fixed points exist for all values of Nf outside of a small window situated at low values Nf and become weakly coupled in the large Nf-limit. Symmetry-wise, they correspond to “quasi-chiral” and “non-chiral” fixed points. The former come with enhanced predictive power, fixing one of the couplings via the asymptotic safety condition. Moreover, the interplay of the fixed points allows for cross-overs from the non-chiral to the chiral fixed point, giving a dynamical mechanism for restoring the symmetry approximately at intermediate scales. Our discussion of chiral symmetry breaking effects provides strong indications that the topology of spacetime plays a crucial role when analyzing whether quantum gravity admits light chiral fermions.

Measurement of thermodynamic temperature of high temperature fixed points

2013 ◽  
Author(s):  
V. R. Gavrilov ◽  
B. B. Khlevnoy ◽  
D. A. Otryaskin ◽  
I. A. Grigorieva ◽  
M. L. Samoylov ◽  
...  
Keyword(s):  
High Temperature ◽  
Fixed Points ◽  
Thermodynamic Temperature ◽  
Temperature Fixed Points ◽  
High Temperature Fixed Points
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