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Wyszukujesz frazę "thermal fluctuations" wg kryterium: Temat


Wyświetlanie 1-3 z 3
Tytuł:
Machine tool distortion estimation due to environmental thermal fluctuations – a focus on heat transfer coefficient
Autorzy:
Da Silva, P.
Pena-Gonzalez, L. E.
Tanabe, I.
Takahashi, S.
Powiązania:
https://bibliotekanauki.pl/articles/99879.pdf
Data publikacji:
2018
Wydawca:
Wrocławska Rada Federacji Stowarzyszeń Naukowo-Technicznych
Tematy:
environmental thermal fluctuations
thermal deformation
machine tool
heat transfer coefficient
Opis:
Thermally induced errors have been approached in multiple ways due to the influence these have over the positional accuracy of a machine tool. Here, approaches regarding environmental thermal fluctuations surrounding a machine tool remain to be explored in detail. These fluctuations have been explored in terms of the heat transfer coefficient and thermal radiation of the machine shop walls, as well as in terms of seasonality and varying thermal gradients. This paper presents additional considerations regarding environmental temperature perturbations, as heat transfer coefficient fluctuations in the machine shop were thought to play a significant role in machine tool thermal deformation a broader term for these phenomena, environmental thermal fluctuations, was defined and evaluated. Specifically, an environmental thermal data survey of a machine shop was explored. This data was then applied to a NC milling machine and a CNC jig borer FEM analyses and compared to experimental data. FEM simulations were then used to demonstrate that convection regimes and heat transfer coefficient values at a machine shop have a significant influence over machining precision. Here, under maximum and minimum heat transfer coefficient values, the NC milling machine and CNC jig borer simulations results showed an error of cut difference up to 36.5 μm and 18.17 μm, respectively. In addition, as the importance of the heat transfer coefficient was highlighted, considerations regarding machine tool surface color were deemed relevant and were described.
Źródło:
Journal of Machine Engineering; 2018, 18, 2; 17-30
1895-7595
2391-8071
Pojawia się w:
Journal of Machine Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spatial and seasonal variability of sub-daily water temperature dynamics in the lowland agricultural catchment of the Wkra River
Autorzy:
Skorupa, Weronika
Łaszewski, Maksym A.
Powiązania:
https://bibliotekanauki.pl/articles/28411638.pdf
Data publikacji:
2023
Wydawca:
Instytut Technologiczno-Przyrodniczy
Tematy:
river water temperature
thermal fluctuations
Mazovia
Central Poland
hourly variations
thermal conditions
Opis:
The paper concentrates on seasonal and spatial variations of sub-daily water temperature dynamics in lowland agricultural streams. Temperature monitoring was carried out in 24 sampling sites distributed along the tributaries of the Wkra River during the hydrological year 2021. Statistical analysis of the obtained data documented the highest water temperature dynamics in the morning, from 5:00 to 9:00 CEST, while the lowest - from 14:00 to 18:00 CEST. Seasonally, greater water dynamics were noted in the winter, expressed by a coefficient of variation reaching up to 100%. Spatially, the highest dynamics occurred in sites with the lowest proportion of riparian vegetation, while the lowest dynamics was related to higher catchment area. In the winter, the minimum daily values were recorded most frequently in the morning hours, while maximum values in the afternoon. A similar pattern was observed in the summer, but with much lower dispersion of the relative frequencies. It was found that in the winter, the dominant influence on temperature dynamics was exerted in the upstream catchment area, while in the summer, a negative relationship with riparian shade was marked. The findings suggest that the presence of riparian vegetation reduces diurnal dynamics of water temperature and is simultaneously extremely important in prolonging the duration of optimum fluctuation, responsible for the proper development of poikilothermic organisms.
Źródło:
Journal of Water and Land Development; 2023, 59; 153--163
1429-7426
2083-4535
Pojawia się w:
Journal of Water and Land Development
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An analysis of the thermal capacity in Gravitons
Autorzy:
Malaver, Manuel
Powiązania:
https://bibliotekanauki.pl/articles/1179635.pdf
Data publikacji:
2017
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
Fluctuations
Gravitons
Microscopic model
Statistical mechanics
Thermal capacity
Opis:
In this paper, we have considered a microscopic model based in the statistical mechanics for gravitons proposed for Viaggiu (2017). We obtain an analytical expression for the thermal capacity CV in gravitons. It is predicted in this research the behavior of the thermal capacity in the limit of high and low temperature. We have also obtained the fluctuations of energy for gravitons with the equation for CV . We found that the value of the fluctuation is the same that would be obtained in a gas with internal energy U=2NKBT when T→∞.
Źródło:
World Scientific News; 2017, 72; 34-40
2392-2192
Pojawia się w:
World Scientific News
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-3 z 3

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