Mechanism of Ion Transport in Cooled and Supercooled Water at High Pressure

1983 ◽  
Vol 22 ◽  
Author(s):  
M. Nakahara ◽  
N. Takisawa ◽  
J. Osugi
Keyword(s):  
Room Temperature ◽  
Pressure Coefficient ◽  
Water Structure ◽  
Continuum Theory ◽  
Supercooled Water ◽  
Ionic Mobility ◽  
Dielectric Friction ◽  
Friction Theory ◽  
The Difference ◽  
The Continuum

ABSTRACTAs predicted by the Hubbard-Onsager continuum dielectric friction theory for ionic mobility in solution, the observed pressure coefficient of the difference ζ between the observed ionic drag coefficient and the Stokes law friction (4πηR), is negative for the small ion Li+ even at low temperatures where the water structure is highly developed. For the large ion Cs+, however, it is positive at any temperature in contrast to the theoretical prediction, its magnitude being larger at lower temperatures and pressures. The anomaly is shown also by the medium-sized ion K+ below room temperature. The passing-through-cavities (PTC) mechanism has been proposed to explain the limitations of the continuum theory.

scholarly journals Prediction of initial shape of functionally graded ceramic pre-forms for near-net-shape sintering

2003 ◽  
Vol 35 (1) ◽  
pp. 5-12 ◽  
Author(s):  
A.L. Maximenko ◽  
Der Biest ◽  
E.A. Olevsky
Keyword(s):  
Numerical Procedure ◽  
Continuum Theory ◽  
Functionally Graded ◽  
Theoretical Determination ◽  
Initial Shape ◽  
Ceramic Components ◽  
Near Net Shape ◽  
The Difference ◽  
The Continuum

Sintering of macroscopically inhomogeneous ceramic components is always accompanied by shape distortions due to the difference in shrinkage rates of powder elements. The objective of the present investigation is the theoretical determination of initially distorted shapes of the green bodies needed to provide near-net-shape sintered components. Calculations are based on a finite element implementation of the continuum theory of sintering. In this theory, sintering is considered as a creep under the influence of the compressive ?sintering stress?. To predict the initial shapes of the components the ?inverse? numerical procedure is used when the component is assumed to swell from the final shape to the initial one under the influence of the pressure equal (with the exception of sign) to the sintering stress.

scholarly journals Plastic failure zone characteristics and stability control technology of roadway in the fault area under non-uniformly high geostress: A case study from Yuandian Coal Mine in Northern Anhui Province, China

2020 ◽  
Vol 12 (1) ◽  
pp. 406-424 ◽  
Author(s):  
Yaoguang Huang ◽  
Aining Zhao ◽  
Tianjun Zhang ◽  
Weibin Guo
Keyword(s):  
Numerical Methods ◽  
Numerical Solutions ◽  
Stress Test ◽  
Pressure Coefficient ◽  
Stability Control ◽  
Failure Zone ◽  
Plastic Failure ◽  
Comparison Results ◽  
High Geostress ◽  
The Difference

AbstractIn order to explore the effective support method for deep broken roadway, based on the in situ stress test results, the analytical and numerical solutions of the stress and the range of plastic failure zone (PFZ) in a circular roadway subjected to non-uniform loads were obtained using analytical and finite difference numerical methods based on the elastoplastic theory, respectively. Their comparison results show that the analytical and numerical methods are correct and reasonable. Furthermore, the high geostress causes the stress and range of PFZ in roadway roof and floor to increase sharply while those in roadway ribs decrease. Moreover, the greater the difference of horizontal geostress in different horizontal directions is, the larger the range of PFZ in roadway roof and floor is. The shape of PFZ in roadway varies with the ratio of horizontal lateral pressure coefficient in x-direction and y-direction. Finally, according to the distribution characteristics of PFZ and range of PFZ under the non-uniformly high geostress, this paper has proposed a combined support scheme, and refined and optimized supporting parameters. The field monitoring results prove that the roadway deformation and fracture have been effectively controlled. The research results of this paper can provide theoretical foundation as well as technical reference for the stability control of deep broken roadway under non-uniformly high geostress.

Confirming the continuum theory of dynamic brittle fracture for fast cracks

Nature ◽  
10.1038/16891 ◽  
1999 ◽  
Vol 397 (6717) ◽  
pp. 333-335 ◽  
Author(s):  
Eran Sharon ◽  
Jay Fineberg
Keyword(s):  
Brittle Fracture ◽  
Continuum Theory ◽  
Dynamic Brittle Fracture ◽  
The Continuum

scholarly journals Matrix integrals & finite holography

2021 ◽  
Vol 2021 (6) ◽  
Author(s):  
Dionysios Anninos ◽  
Beatrix Mühlmann
Keyword(s):  
Critical Exponents ◽  
Continuum Theory ◽  
Point Of View ◽  
Leading Order ◽  
Minimal Models ◽  
Point Evaluation ◽  
Brst Cohomology ◽  
Matrix Integrals ◽  
The Matrix ◽  
The Continuum

Abstract We explore the conjectured duality between a class of large N matrix integrals, known as multicritical matrix integrals (MMI), and the series (2m − 1, 2) of non-unitary minimal models on a fluctuating background. We match the critical exponents of the leading order planar expansion of MMI, to those of the continuum theory on an S2 topology. From the MMI perspective this is done both through a multi-vertex diagrammatic expansion, thereby revealing novel combinatorial expressions, as well as through a systematic saddle point evaluation of the matrix integral as a function of its parameters. From the continuum point of view the corresponding critical exponents are obtained upon computing the partition function in the presence of a given conformal primary. Further to this, we elaborate on a Hilbert space of the continuum theory, and the putative finiteness thereof, on both an S2 and a T2 topology using BRST cohomology considerations. Matrix integrals support this finiteness.

Effect of titanium alloys elasticity modulus on warping of stamped blanks during cooling

2021 ◽  
pp. 221-227
Author(s):  
M.O. Smirnov ◽  
A.M. Zolotov ◽  
A.M. Tyukhtyaev
Keyword(s):  
Mathematical Modeling ◽  
Titanium Alloys ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Elasticity Modulus ◽  
Preliminary Deformation ◽  
Wide Spread ◽  
Temperature Dependences ◽  
Cumulative Deformation ◽  
The Difference

Wide spread in the values of the elasticity modulus of the titanium VT6 alloy and its analogs Ti—6Al—4V, Ti—6Al—4V ELI at room temperature and at elevated temperatures is revealed аs result of the literature sources analysis. The data are ambiguous, the available temperature dependences of the elasticity modulus have very different values starting from the temperature T l 500 °C. Mathematical modeling of the warping process is carried out on the example of figurine-shaped stamped blank of turbine blade using various dependences of the elasticity modulus on temperature. Cases of warping during cooling of stamped blank after cooling-down in stamp with and without cumulative deformation are considered. The difference in the course of thermal deformations during the cooling of the workpiece is obtained using different temperature dependences of the elasticity modulus. The presence of preliminary deformation increases the warping of the workpieces.

Study on Simulation Experiment with Universal Pass Rolling Deformation for Heavy Rail

2012 ◽  
Vol 430-432 ◽  
pp. 525-529 ◽  
Author(s):  
Lin Chen ◽  
Ke Xin Bi
Keyword(s):  
Finite Element ◽  
Pressure Coefficient ◽  
Small Deformation ◽  
Dimensional Accuracy ◽  
Research Unit ◽  
Finite Element Software ◽  
Universal Mill ◽  
The Difference ◽  
Rolling Deformation ◽  
Heavy Rail

Using the finite element software ANSYS/LS-DYNA for the universal rolling machine to simulate,research unit of the universal rolling deformation etc, and the use of universal mill for heavy rail rolling to simulate of lead samples, study of both. By comparing experimental results, the results show rolling simulation of laboratory lead samples and finite element simulations of computer are basically the same, use the universal pass, the difference of pressure coefficient for the rail head and rail base and rail back that work on the workpiece at the universal pass is small, deformation of workpiece is uniformity, it ensure the dimensional accuracy of the finished rail on the rail section.

Determination of Incompressible Flow Friction in Smooth Circular and Noncircular Passages: A Generalized Approach Including Validation of the Nearly Century Old Hydraulic Diameter Concept

1988 ◽  
Vol 110 (4) ◽  
pp. 431-440 ◽  
Author(s):  
N. T. Obot
Keyword(s):  
Reynolds Number ◽  
Friction Factor ◽  
Critical Reynolds Number ◽  
Pressure Coefficient ◽  
Hydraulic Diameter ◽  
Length Scale ◽  
The Difference ◽  
Friction Method ◽  
Reduced Data

It has been demonstrated conclusively that the widely observed differences in data for frictional pressure coefficient between circular and noncircular passages derive from the inseparably connected effects of transition and the choice of a length scale. A relatively simple approach, the critical friction method (CFM), has been developed and when applied to triangular, rectangular, and concentric annular passages, the reduced data lie with remarkable consistency on the circular tube relations. In accordance with the theory of dynamical similarity, it has also been shown that noncircular duct data can be reduced using the hydraulic diameter or any arbitrarily defined length scale. The proposed method is what is needed to reconcile such data with those for circular tubes. With the hydraulic diameter, the critical friction factor almost converges to a universal value for all passages and the correction is simply that required to account for the difference in critical Reynolds number. By contrast, with any other linear parameter, two corrections are needed to compensate for variations in critical friction factor and Reynolds number. Application of the method to roughened passages is discussed.

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