The limiting behavior of the gradient function for an isolated paraboloid growing in a positive temperature gradient

1998 ◽  
Vol 191 (1-2) ◽  
pp. 298-302
Author(s):  
V Laxmanan
Keyword(s):  
Temperature Gradient ◽  
Positive Temperature ◽  
Limiting Behavior ◽  
Gradient Function ◽  
Positive Temperature Gradient

Investigation of concrete box girder positive temperature gradient patterns considering different climatic regions

Structures ◽  
2022 ◽  
Vol 35 ◽  
pp. 591-607
Author(s):  
Chenzhi Cai ◽  
Shiji Huang ◽  
Xuhui He ◽  
Tieming Zhou ◽  
Yunfeng Zou
Keyword(s):  
Temperature Gradient ◽  
Positive Temperature ◽  
Box Girder ◽  
Climatic Regions ◽  
Concrete Box Girder ◽  
Positive Temperature Gradient

Analytical Solutions and Derivation of Relative Permeabilities for Water-Heavy Oil Displacement and Gas-Heavy Oil Gravity Drainage Under Non-Isothermal Conditions

2016 ◽  
Vol 19 (01) ◽  
pp. 181-191 ◽  
Author(s):  
F. J. Argüelles-Vivas ◽  
T.. Babadagli
Keyword(s):  
Temperature Gradient ◽  
Relative Permeability ◽  
Heavy Oil ◽  
Variable Temperature ◽  
Spontaneous Imbibition ◽  
Analytical Models ◽  
Gravity Drainage ◽  
Positive Temperature ◽  
Relative Permeability Curves ◽  
Isothermal Gas

Summary Analytical models were developed for non-isothermal gas/heavy-oil gravity drainage and water-heavy oil displacements in round capillary tubes including the effects of a temperature gradient throughout the system. By use of the model solution for a bundle of capillaries, relative permeability curves were generated at different temperature conditions. The results showed that water/gas-heavy oil interface location, oil-drainage velocity, and production rate depend on the change of oil properties with temperature. The displacement of heavy oil by water or gas was accelerated under a positive temperature gradient, including the spontaneous imbibition of water. Relative permeability curves were greatly affected by temperature gradient and showed significant changes compared with the curves at constant temperature. Clarifications were made as to the effect of variable temperature compared with the constant (but high) temperatures throughout the bundle of capillaries.

scholarly journals Temperature drives diversification in a model adaptive radiation

2018 ◽  
Vol 285 (1886) ◽  
pp. 20181515 ◽  
Author(s):  
Quan-Guo Zhang ◽  
Han-Shu Lu ◽  
Angus Buckling
Keyword(s):  
Genetic Variation ◽  
Temperature Gradient ◽  
Temperature Dependence ◽  
Adaptive Radiation ◽  
Low Temperatures ◽  
Energy Availability ◽  
Positive Temperature ◽  
Direct Effects ◽  
Diversifying Selection ◽  
Ancestral Type

The warmer regions harbour more species, attributable to accelerated speciation and increased ecological opportunities for coexistence. While correlations between temperature and energy availability and habitat area have been suggested as major drivers of these biodiversity patterns, temperature can theoretically also have direct effects on the evolution of diversity. Here, we experimentally studied the evolution of diversity in a model adaptive radiation of the bacterium Pseudomonas fluorescens across a temperature gradient. Diversification increased at higher temperatures, driven by both faster generation of genetic variation and stronger diversifying selection. Specifically, low temperatures could limit the generation of diversity, suggested by the observation that supply of genetic variation through immigration increased diversity at low, but not high temperatures. The two major determinants of mutation supply, population size and mutation rate, both showed a positive temperature dependence. Stronger diversifying selection in warmer environments was suggested by promoted coexistence, and further explicitly inferred by the ability of evolved phenotypes to invade the ancestral type from rare. We discuss possible physiological and environmental mechanisms underlying the findings, most of which are likely to be general.

Foundation Modeling for Jointed Concrete Pavements

2000 ◽  
Vol 1730 (1) ◽  
pp. 34-42 ◽  
Author(s):  
William G. Davids
Keyword(s):  
Finite Element ◽  
Temperature Gradient ◽  
Load Transfer ◽  
Plain Concrete ◽  
Positive Temperature ◽  
Concrete Pavements ◽  
Finite Element Program ◽  
Joint Load ◽  
Foundation Type ◽  
Dense Liquid

Issues related to the finite element modeling of base and subgrade materials under jointed plain concrete pavements are examined. The threedimensional finite element program EverFE, developed in conjunction with the Washington State Department of Transportation, was employed for the analyses. The relevant modeling capabilities of EverFE are detailed, including the ability to model multiple foundation layers, the incorporation of loss of contact between slab and base, and the efficient iterative solution strategies that make large three-dimensional finite element analyses possible on desktop computers. The results of parametric studies examining the effects of foundation type (layered elastic and dense liquid) and properties on the response of jointed plain concrete pavements subjected to axle and thermal loads are presented. Special attention is paid to the interactions between joint load transfer effectiveness and foundation type, and joint load transfer is shown to change significantly with different foundation models and properties. A consideration of simultaneous thermal and axle loadings indicates that the effect of foundation type and properties on critical slab stresses caused by edge loading and a positive temperature gradient is relatively small. However, the slab response is quite sensitive to foundation type for a combined negative temperature gradient and corner loading. On the basis of these results, use of an equivalent dense liquid foundation modulus in mechanistic rigid pavement analysis or design is not recommended when stiff base layers are present.

Effect of FWD Testing Position on Modulus of Subgrade Reaction

2014 ◽  
Vol 518 ◽  
pp. 53-59 ◽  
Author(s):  
S.N. Shoukry ◽  
G.W. William ◽  
M.Y. Riad ◽  
J.C. Prucz
Keyword(s):  
Temperature Gradient ◽  
Early Morning ◽  
Slab Thickness ◽  
Positive Temperature ◽  
Falling Weight Deflectometer ◽  
Subgrade Reaction ◽  
K Value ◽  
Modulus Of Subgrade Reaction ◽  
Late Evening ◽  
Falling Weight

This paper discusses the variation of the Modulus of subgrade reaction (k) backcalculated from slab deflection basins, interactive with the location of the Falling Weight Deflectometer (FWD) load pulse, and curling of slabs due to daily temperature variations. The k-value was calculated following the AASHTO design guides procedures, while deflection basins were recorded at an interval of 3 to 4 hours along the day on an instrumented concrete pavement test section in West Virginia. The state of deformation of the slabs are continuously monitored, through dowel bar bending measurements and records of the temperature gradient profiles through the slab thickness, as well as joint openings every 20 minutes. The results indicated that the backcalculated k-values are greatly affected by the positive temperature gradient, and the least variation in (k) was found in the slab center. In order to minimize errors in back-calculations of k-values, it is recommended to perform the FWD test for recording deflection basins in the interior of the slab during late evening or in the early morning.

scholarly journals Thermal Gradients in the Outer Lunar Layers

1972 ◽  
Vol 47 ◽  
pp. 372-376
Author(s):  
J. A. Bastin ◽  
S. J. Pandya ◽  
D. A. Upson
Keyword(s):  
Heat Flux ◽  
Temperature Gradient ◽  
Lunar Surface ◽  
Thermal Flux ◽  
Temperature Measurements ◽  
Thermal Gradients ◽  
Positive Temperature ◽  
Temperature Differential ◽  
Lunar Interior ◽  
Apollo Mission

During the next Apollo mission Apollo 15, it is planned to fix thermocouples at various depths up to 3 m below the lunar surface. It seems likely that the resulting temperature measurements will show a positive temperature differential with depth resulting from a net outward heat flux. It is the purpose of this paper to examine experiments already carried out which indicate a temperature gradient. Since the thermal flux is of direct importance in fundamental problems of lunar origin and the nature of the lunar interior, the relation between this quantity and the temperature gradient will be examined.

scholarly journals Results of Measurements in the 309 Meter Bore Hole at Byrd Station, Antarctica

1963 ◽  
Vol 4 (36) ◽  
pp. 771-784 ◽  
Author(s):  
Anthony J. Gow
Keyword(s):  
Negative Temperature ◽  
Drill Hole ◽  
Climatic Changes ◽  
Positive Temperature ◽  
Closure Rate ◽  
Time Of Application ◽  
Differential Motion ◽  
Constant Gradient ◽  
Positive Temperature Gradient ◽  
Hole Closure

AbstractTemperature, inclination, and closure have been measured in a 309 m. deep drill hole at Byrd Station, Antarctica. The results of five series of measurements taken yearly since February 1958 show that temperatures below 70 m. have remained constant since December 1958, that the closure rate has accelerated, and that the hole has undergone negligible inclination from the vertical. Anomalous temperatures in the upper levels of the drill hole are attributed to the steel casing that was permanently emplaced to a depth of 36 m. during drilling in 1957–58. A positive temperature gradient was observed in the casing, but negative gradients exist below the casing and a constant gradient profile is developed below 170 m. Both ice motion and climatic changes at Byrd Station are thought to have contributed to the formation of the observed negative temperature gradients. Insignificant bending of the drill hole would imply negligible differential motion in the upper 300 m. of the 2,400 m. thick ice sheet at Byrd Station. The rate of hole closure has accelerated throughout the 4 yr. period of observations, except at the bottom of the drill hole, where the most recent measurements (February 1962) show that some constraint is now developing. Deformation rates throughout the drill hole are not proportional to some constant power of the stress; instead the value of the power has been found to increase with both increasing stress and time of application of stress. This behavior is attributed to some process of continuous deformational recrystallization of ice in the walls of the drill hole. A recoring of the deformed drill hole to investigate such effects is advocated.

scholarly journals Results of Measurements in the 309 Meter Bore Hole at Byrd Station, Antarctica

1963 ◽  
Vol 4 (36) ◽  
pp. 771-784 ◽  
Author(s):  
Anthony J. Gow
Keyword(s):  
Negative Temperature ◽  
Drill Hole ◽  
Climatic Changes ◽  
Positive Temperature ◽  
Closure Rate ◽  
Time Of Application ◽  
Differential Motion ◽  
Constant Gradient ◽  
Positive Temperature Gradient ◽  
Hole Closure

AbstractTemperature, inclination, and closure have been measured in a 309 m. deep drill hole at Byrd Station, Antarctica. The results of five series of measurements taken yearly since February 1958 show that temperatures below 70 m. have remained constant since December 1958, that the closure rate has accelerated, and that the hole has undergone negligible inclination from the vertical. Anomalous temperatures in the upper levels of the drill hole are attributed to the steel casing that was permanently emplaced to a depth of 36 m. during drilling in 1957–58. A positive temperature gradient was observed in the casing, but negative gradients exist below the casing and a constant gradient profile is developed below 170 m. Both ice motion and climatic changes at Byrd Station are thought to have contributed to the formation of the observed negative temperature gradients. Insignificant bending of the drill hole would imply negligible differential motion in the upper 300 m. of the 2,400 m. thick ice sheet at Byrd Station. The rate of hole closure has accelerated throughout the 4 yr. period of observations, except at the bottom of the drill hole, where the most recent measurements (February 1962) show that some constraint is now developing. Deformation rates throughout the drill hole are not proportional to some constant power of the stress; instead the value of the power has been found to increase with both increasing stress and time of application of stress. This behavior is attributed to some process of continuous deformational recrystallization of ice in the walls of the drill hole. A recoring of the deformed drill hole to investigate such effects is advocated.

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