A mechanistic theory of ice lens formation in fine-grained soils

1980 ◽  
Vol 17 (4) ◽  
pp. 473-486 ◽  
Author(s):  
Jean-Marie Konrad ◽  
Norbert R. Morgenstern
Keyword(s):  
Steady State ◽  
Heat Flow ◽  
Freezing Temperature ◽  
Cold Side ◽  
Freezing Soil ◽  
Fine Grained ◽  
Mechanistic Theory ◽  
Two Parameters ◽  
Lens Formation

This study reveals that a freezing soil can be characterized by two parameters, the segregation-freezing temperature Ts and the overall permeability of the frozen fringe [Formula: see text]. During unsteady heat flow, the variation of these parameters with temperature produces rhythmic ice banding in fine-grained soils. At the onset of steady-state conditions, freezing tests conducted at a fixed warm end temperature showed that Ts was independent of the cold side step temperature. In addition, a model is presented that indicates how the overall permeability of the frozen fringe can be calculated without detailed measurements at the scale of the frozen fringe. It is also constant in the tests reported here.

Prediction of frost heave in the laboratory during transient freezing

1982 ◽  
Vol 19 (3) ◽  
pp. 250-259 ◽  
Author(s):  
J.-M. Konrad ◽  
N. R. Morgenstern
Keyword(s):  
Mass Transfer ◽  
Steady State ◽  
Temperature Gradient ◽  
Water Intake ◽  
Applied Load ◽  
Frost Heave ◽  
Freezing Soil ◽  
Fine Grained ◽  
Segregation Potential ◽  
Rate Of Cooling

Previous studies have demonstrated that, close to steady-state conditions, the ratio of the water intake velocity to the temperature gradient across the frozen fringe, called the segregation potential, is an important property characterizing a freezing soil. Under the more general conditions of transient freezing it is shown that the freezing characteristics of a given soil under zero applied load are defined by the segregation potential, the suction at the frozen–unfrozen interface, and the rate of cooling of the frozen fringe. These parameters form a relationship called the characteristic frost heave surface that can be used to predict mass transfer during the freezing of fine-grained soils. Examples of freezing tests conducted under various conditions are reproduced numerically to illustrate the fundamental character of this surface.

Steady-State Parametric Optimization and Transient Characterization of Heat Flow Regulation With Binary Diffusion

2020 ◽  
Vol 10 (12) ◽  
pp. 1996-2007
Author(s):  
Tanya Liu ◽  
James W. Palko ◽  
Joseph S. Katz ◽  
Feng Zhou ◽  
Ercan M. Dede ◽  
...  
Keyword(s):  
Steady State ◽  
Heat Flow ◽  
Parametric Optimization ◽  
Flow Regulation ◽  
Binary Diffusion

scholarly journals Reconstructing bottom water temperatures from measurements of temperature and thermal diffusivity in marine sediments

2014 ◽  
Vol 11 (5) ◽  
pp. 2391-2422
Author(s):  
F. Miesner ◽  
A. Lechleiter ◽  
C. Müller
Keyword(s):  
Steady State ◽  
Heat Flow ◽  
Water Temperature ◽  
Marine Sediments ◽  
Bottom Water ◽  
Measured Data ◽  
Temperature History ◽  
Artificial Data ◽  
Bottom Water Temperature ◽  
Steady State Heat

Abstract. Temperature fields in marine sediments are studied for various purposes. Often, the target of research is the steady state heat flow as a (possible) source of energy but there are also studies attempting to reconstruct bottom water temperature variations to understand more about climate history. The bottom water temperature propagates into the sediment to different depths, depending on the amplitude and period of the deviation. The steady state heat flow can only be determined when the bottom water temperature is constant while the bottom water temperature history can only be reconstructed when the deviation has an amplitude large enough or the measurements are taken in great depths. In this work, the aim is to reconstruct recent bottom water temperature history such as the last two years. To this end, measurements to depths of up to 6 m shall be adequate and amplitudes smaller than 1 K should be reconstructable. First, a commonly used forward model is introduced and analyzed: knowing the bottom water temperature deviation in the last years and the thermal properties of the sediments, the forward model gives the sediment temperature field. Next, an inversion operator and two common inversion schemes are introduced. The analysis of the inversion operator and both algorithms is kept short, but sources for further reading are given. The algorithms are then tested for artificial data with different noise levels and for two example data sets, one from the German North Sea and one from the Davis Strait. Both algorithms show good and stable results for artificial data. The achieved results for measured data have low variances and match to the observed oceanographic settings. Lastly, the desired and obtained accuracy are discussed. For artificial data, the presented method yields satisfying results. However, for measured data the interpretation of the results is more difficult as the exact form of the bottom water deviation is not known. Nevertheless, the presented inversion method seems rather promising due to its accuracy and stability for artificial data. Continuing to work on the development of more sophisticated models for the bottom water temperature, we hope to cover more different oceanographic settings in the future.

scholarly journals Numerical Simulation of Thermal Conductivity of Foam Glass Based on the Steady-State Method

Materials ◽  
2018 ◽  
Vol 12 (1) ◽  
pp. 54 ◽  
Author(s):  
Zipeng Qin ◽  
Gang Li ◽  
Yan Tian ◽  
Yuwei Ma ◽  
Pengfei Shen
Keyword(s):  
Thermal Conductivity ◽  
Steady State ◽  
Heat Flow ◽  
Thermal Resistance ◽  
Thermal Insulation ◽  
Foam Glass ◽  
Orthogonal Experimental Design ◽  
Carbonate Content ◽  
Steady State Method ◽  
State Method

The effects of fly ash, sodium carbonate content, foaming temperature and foaming time on foam glass aperture sizes and their distribution were analyzed by the orthogonal experimental design. Results from the steady-state method showed a normal distribution of the number of apertures with change in average aperture, which ranges from 0.1 to 2.0 mm for more than 93% of apertures. For a given porosity, the thermal conductivity decreases with the increase of the aperture size. The apertures in the sample have obvious effects in blocking the heat flow transmission: heat flow is quickly diverted to both sides when encountered with the aperture. When the thickness of the sample is constant, the thermal resistance of the foam glass sample increases with increasing porosity, leading to better thermal insulation. Furthermore, our results suggest that the more evenly distributed and orderly arranged the apertures are in the foam glass material, the larger the thermal resistance of the material and hence, the better the thermal insulation.

cAMP, myosin dephosphorylation, and isometric relaxation of airway smooth muscle

1988 ◽  
Vol 64 (2) ◽  
pp. 705-709 ◽  
Author(s):  
P. de Lanerolle
Keyword(s):  
Smooth Muscle ◽  
Steady State ◽  
Muscle Relaxation ◽  
Fold Increase ◽  
Treatment Results ◽  
Myosin Phosphorylation ◽  
Temporal Relationships ◽  
Steady State Levels ◽  
Two Parameters ◽  
Camp Levels

The temporal relationships among increases in adenosine 3',5'-cyclic monophosphate (cAMP) levels, myosin dephosphorylation, and relaxation were investigated to clarify the mechanisms of airway muscle relaxation. Canine tracheal muscles isometrically contracted (82% of maximum force) with 10(-6) M methacholine were relaxed by adding either 4 x 10(-7) M atropine or 4 x 10(-5) M forskolin. Atropine had no effect on cAMP levels; myosin phosphorylation and force, however, decayed at the same rates and these two parameters returned to their basal pre-methacholine levels within 5 min. Forskolin treatment results in about a 10-fold increase in cAMP levels; myosin phosphorylation and force decayed simultaneously to their respective steady-state levels by 10 min but neither parameter returned to its pre-methacholine level. The addition of forskolin to muscles maximally contracted with 10(-4) M methacholine leads to about a 30-fold increase in cAMP levels. However, there are minimal decreases in myosin phosphorylation and force in these muscles. Thus myosin dephosphorylation appears to be essential for airway muscle relaxation, whereas an increase in cAMP in the absence of myosin dephosphorylation is insufficient to cause relaxation. Moreover, myosin dephosphorylation appears to be a common step in the cAMP-independent and cAMP-dependent mechanisms for airway muscle relaxation.

Thermotransport of Noble Metal Impurities in Lead

1972 ◽  
Vol 27 (1) ◽  
pp. 138-140 ◽  
Author(s):  
George A. Sullivan ◽  
Sune Larsson ◽  
Per T. Thernquist
Keyword(s):  
Steady State ◽  
Temperature Dependence ◽  
Noble Metal ◽  
Temperature Gradients ◽  
Electronic Contribution ◽  
Kcal Mole ◽  
Cold Side ◽  
Heat Of Transport ◽  
Metal Impurities ◽  
Significant Temperature

Abstract Steady-state distributions of Au, Ag and Cu tracers in Pb wafers subjected to temperature gradients have been determined. The effective heats of transport were + 5.8 ± 1.1 for Ag, - 0.5 ± 0.3 for Au, and of the order of + 35 for Cu (all in kcal/mole, positive values denoting the impurity migrating to the cold side of the Pb wafer). No significant temperature dependence of the heats of transport could be detected. The results are difficult to reconcile with existing theories of the intrinsic and electronic contribution to the heat of transport.

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