scholarly journals Analysis of Sunshine Temperature Field of Steel Box Girder Based on Monitoring Data

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Hailin Lu ◽  
Jing Hao ◽  
Jiwei Zhong ◽  
Yafei Wang ◽  
Hongyin Yang
Keyword(s):  
Temperature Field ◽  
Temperature Distribution ◽  
Temperature Gradient ◽  
Maximum Temperature ◽  
Temperature Model ◽  
Bridge Site ◽  
Vertical Temperature Gradient ◽  
Vertical Temperature ◽  
Box Girder ◽  
Steel Box Girder

In this study, based on the recorded meteorological data of the bridge site, a spatial-temporal temperature model of a 3-span steel box girder is developed through applying the thermal analysis software TAITHERM. Firstly, the rationality and dependability of the proposed spatial-temporal temperature model are adequately verified by means of implementing the comparison with the measurement data. Then the temperature distribution of the steel box girder is analyzed and discussed in detail. The analytical results show that the time of the bottom of pavement reaching the daily maximum temperature lags behind the top of pavement by 2 or 3 hours due to the thermal insulation effect of pavement, and the maximum vertical temperature gradient of the structure exceeds the existing standards. Moreover, with the help of the analytical model, a parametric study of comprehensively meteorological factors is also performed. The results of the sensitivity analysis indicate that solar radiation is the most significant factor affecting the maximum vertical temperature gradient of the steel box girder, followed by air temperature and wind speed. After that, with the representative values of the extreme meteorological parameters during 100-year return period in Wuhan City in China being considered as the thermal boundary conditions, the temperature distribution of the steel box girder is further studied for investigation purpose. The results demonstrate that the heat conduction process of the steel box girder has distinct “box-room effect,” and it is of great necessity to consider both the actual weather conditions at the bridge site and the “box-room effect” of steel box girder when calculating thermal behaviors of bridge structures. Finally, it is related that the particular method proposed in this paper possesses a satisfactory application prospect for temperature field analysis upon various types of bridges in different regions.

Motion of a drop in a vertical temperature gradient at small Marangoni number – the critical role of inertia

2001 ◽  
Vol 448 ◽  
pp. 197-211 ◽  
Author(s):  
LU ZHANG ◽  
R. SHANKAR SUBRAMANIAN ◽  
R. BALASUBRAMANIAM
Keyword(s):  
Temperature Field ◽  
Temperature Gradient ◽  
Small Parameter ◽  
Asymptotic Expansions ◽  
Peclet Number ◽  
Marangoni Number ◽  
Matched Asymptotic Expansions ◽  
Vertical Temperature Gradient ◽  
Vertical Temperature ◽  
Singular Behaviour

When a drop moves in a uniform vertical temperature gradient under the combined action of gravity and thermocapillarity at small values of the thermal Péclet number, it is shown that inclusion of inertia is crucial in the development of an asymptotic solution for the temperature field. If inertia is completely ignored, use of the method of matched asymptotic expansions, employing the Péclet number (known as the Marangoni number) as the small parameter, leads to singular behaviour of the outer temperature field. The origin of this behaviour can be traced to the interaction of the slowly decaying Stokeslet, arising from the gravitational contribution to the motion of the drop, with the temperature gradient field far from the drop. When inertia is included, and the method of matched asymptotic expansions is used, employing the Reynolds number as a small parameter, the singular behaviour of the temperature field is eliminated. A result is obtained for the migration velocity of the drop that is correct to O(Re2 log Re).

Effects of M.S. 222 Anesthetization on Temperature Selection in Lake Trout, Salvelinus namaycush

1974 ◽  
Vol 31 (1) ◽  
pp. 100-103 ◽  
Author(s):  
C. I. Goddard ◽  
J. W. Lilley ◽  
J. S. Tait
Keyword(s):  
Temperature Distribution ◽  
Temperature Gradient ◽  
Lake Trout ◽  
Salvelinus Namaycush ◽  
Control Fish ◽  
Vertical Temperature Gradient ◽  
Vertical Temperature ◽  
Temperature Selection

Yearling lake trout (Salvelinus namaycush) were anesthetized with a 150 ppm solution of M.S. 222 for 2 min at 10 C. When tested in a vertical temperature gradient, their behavior was abnormal for 5 days following anesthetization. Initially, they remained at the bottom of the gradient tank, as much as 63% of the time, and when they did swim up into the gradient, their temperature selection was much less precise than that of control fish. The percentage of fish on the bottom declined daily, and on the 6th day their temperature distribution did not differ from that of controls.

scholarly journals Analysis of the occurrence of natural convection in a bed of bars in vertical temperature gradient conditions

2013 ◽  
Vol 34 (1) ◽  
pp. 71-83
Author(s):  
Rafał Wyczółkowski ◽  
Dorota Musiał
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Heat Treatment ◽  
Natural Convection ◽  
Temperature Distribution ◽  
Temperature Gradient ◽  
Free Convection ◽  
Vertical Temperature Gradient ◽  
Vertical Temperature ◽  
Rayleigh Criterion

Abstract The reason for undertaking this study was to determine the possible involvement of natural convection in the global heat transfer, that occurs in the heated steel rods bed. This problem is related to the setting of the effective thermal conductivity of the bars bed. This value is one of the boundary conditions for heating modeling of steel rods bundles during heat treatment. The aim of this study was to determine for which geometry of the bed bars, there will be no free convection. To analyze the problem the Rayleigh criterion was used. It was assumed that for the value of the number Ra < 1700 convection in the bed bars does not occur. For analysis, the results of measurements of the temperature distribution in the unidirectionally heated beds of bars were used. It has been shown, that for obtained, during the test, differences of temperature between the surfaces of adjacent rods, convection can occur only when the diameter of the rod exceeds 18 mm.

scholarly journals Experimental Study of the Temperature Distribution in CRTS-II Ballastless Tracks on a High-Speed Railway Bridge

2020 ◽  
Vol 10 (6) ◽  
pp. 1980 ◽  
Author(s):  
Lei Zhao ◽  
Ling-Yu Zhou ◽  
Guang-Chao Zhang ◽  
Tian-Yu Wei ◽  
Akim D. Mahunon ◽  
...  
Keyword(s):  
High Temperature ◽  
Temperature Distribution ◽  
Temperature Gradient ◽  
High Speed ◽  
Railway Track ◽  
Vertical Temperature ◽  
High Speed Railway ◽  
Extreme High Temperature ◽  
Transverse Temperature ◽  
Temperature Test

To study the temperature distribution in the China Railway Track System Type II ballastless slab track on a high-speed railway (HSR) bridge, a 1:4 scaled specimen of a simply-supported concrete box girder bridge with a ballastless track was constructed in laboratory. Through a rapid, extreme high temperature test in winter and a conventional high temperature test in summer, the temperature distribution laws in the track on the HSR bridge were studied, and the vertical and transverse temperature distribution trend was suggested for the track. Firstly, the extreme high temperature test results showed that the vertical temperature and the vertical temperature difference distribution in the track on HSR bridge were all nonlinear with three stages. Secondly, the extreme high temperature test showed that the transverse temperature distribution in the track was of quadratic parabolic nonlinear form, and the transverse temperature gradient in the bottom base was significantly higher than that of the other layers of the track. Thirdly, the three-dimensional temperature distribution in the track on HSR bridge was a nonlinear, three-stage surface. Furthermore, similar regularities were also obtained in the conventional high temperature test, in which the temperature span ranges were different from those of the extreme high temperature test. In addition, the conventional high temperature test also showed that under the natural environment conditions, the internal temperature gradient in the track layers changed periodically (over a period of 24 h).

Effects of Age and Overhead Illumination on Temperatures Preferred by Underyearling Rainbow Trout, Salmo gairdneri, in a Vertical Temperature Gradient

1978 ◽  
Vol 35 (11) ◽  
pp. 1430-1433 ◽  
Author(s):  
Wen-Hwa Kwain ◽  
Robert W. McCauley
Keyword(s):  
Rainbow Trout ◽  
Temperature Gradient ◽  
Temperature Gradients ◽  
Salmo Gairdneri ◽  
Vertical Temperature Gradient ◽  
Temperature Preference ◽  
Vertical Temperature ◽  
Preferred Temperature ◽  
Distribution Of Fish ◽  
Vertical Gradients

During their first 12 mo of life rainbow trout, Salmo gairdneri, preferred progressively cooler temperatures as they grew older; 19 °C was selected during the 1st mo and the selected temperature declined by intervals of 0.5 °C for each of the following months up to the 3rd mo. Fish swam higher in temperature gradients exposed to overhead illumination than in those in total darkness. This trend was reversed during the following 9 mo. These findings demonstrate the important role that age plays in the temperature preference of this species and the influence that overhead light may have on the distribution of fish in vertical gradients. Key words: preferred temperature, age, Salmo gairdneri, light gradients

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