Quantification of free convection effects on 1 kg mass standards. - In: Metrologia, ISSN 1681-7575, Bd. 52 (2015), 6, S. 835-841
We determine the free-convection effects and the resulting mass differences in a high-precision mass comparator for cylindrical and spherical 1 kg mass standards at different air pressures. The temperature differences are chosen in the millikelvin range and lead to microgram updrafts. Our studies reveal a good agreement between the measurements and direct numerical simulations of the Boussinesq equations of free thermal convection. A higher sensitivity to the free convection effects is found for the spherical case compared to the cylindrical one. We also translate our results on the free convection effects into a form which is used in fluid mechanics: a dimensionless updraft coefficient as a function of the dimensionless Grashof number Gr that quantifies the thermal driving due to temperature differences. This relation displays a unique scaling behavior over nearly four decades in Gr and levels off into geometry-specific constants for the very small Grashof numbers. The obtained results provide a rational framework for estimating systematic errors in mass metrology due to the effects of free convection.
https://doi.org/10.1088/0026-1394/52/6/835
Hygrostat based on adsorption processes controlled by a high precision chilled dew point mirror :
Feuchtluftgenerator auf Basis eines Sorptionshygrostaten mit einem Hochpräzisionstauspiegel. - In: Technisches Messen, ISSN 2196-7113, Bd. 82 (2015), 10, S. 477-484
https://doi.org/10.1515/teme-2015-0022
Towards metering tap water by Lorentz force velocimetry. - In: Measurement science and technology, ISSN 1361-6501, Bd. 26 (2015), 11, S. 115302, insges. 11 S.
https://doi.org/10.1088/0957-0233/26/11/115302
White-light interferometers with polarizing optics for length measurements with an applicable zero-point detection. - In: Measurement science and technology, ISSN 1361-6501, Bd. 26 (2015), 8, S. 084010, insges. 15 S.
https://doi.org/10.1088/0957-0233/26/8/084010
Concentric run-out error determination of rotary tables with an interferometric probe head :
Interferometrische Rundlauffehlerbestimmung von Drehtischen für die optische Rundheitsmessung. - In: Technisches Messen, ISSN 2196-7113, Bd. 82 (2015), 6, S. 299-308
http://dx.doi.org/10.1515/teme-2015-0021
PCM-shielding of precision measuring equipment by means of latent heat. - In: Precision engineering, Bd. 42 (2015), S. 80-84
https://doi.org/10.1016/j.precisioneng.2015.04.002
Stan ta perspektivi rozvitku kompьjuterizovanich sistem kontrolju topologii poverchni :
State and prospects of computerized systems monitoring the topology of surfaces, based on white light interferometry. - In: Computational problems of electrical engineering, ISSN 2309-4834, Bd. 4 (2014), 1, S. 75-80
This paper describes a computerized system for object topology control based on a white light interferometer. The theoretical fundamentals of white light interferometry and mathematical model of an interferogram are presented. An overview and comparative analysis of methods for the reconstruction of the topology of surfaces based on a white light interferogram are performed, their main advantages and disadvantages are defined, and the objectives for the development of computerized systems are formulated.
http://ena.lp.edu.ua:8080/xmlui/handle/ntb/26620
Direct Lorentz force compensation flowmeter for electrolytes. - In: Applied physics letters, ISSN 1077-3118, Bd. 105 (2014), 22, S. 223510, insges. 4 S.
http://dx.doi.org/10.1063/1.4903235
A new approach to test torque transducers under dynamic reference regimes. - In: Measurement, Bd. 58 (2014), S. 354-362
A system is proposed to test torque transducers under reference dynamic regimes, where the reference torque is provided by the application of angular acceleration to a coupled mass moment of inertia. The dynamic regimes include different angular velocity intervals, angular velocity steps and high torque rates. A basic general assembly is proposed and theoretical and practical analyses are performed to determine the primary parameters and depict components. The results show that the angular velocity and torque curves are repeatable and also that the simultaneous responses of torque and acceleration are linear. The mass moments of inertia involved in the measurement process are evaluated. The results provide a positive direction for future tests with transducers and the objective to fill the gap in the metrological traceability chain for torque measurement with dynamic tests and sensor verification.
http://dx.doi.org/10.1016/j.measurement.2014.09.020
PCMs for improving measurement and manufacturing precision. - In: Mikroniek, ISSN 0026-3699, Bd. 54 (2014), 3, S. 15-19