Symmetry breaking of Worthington jets by gradients in liquid pool depth

Vacuum arc remelting (VAR) is an industrial metallurgical process widely used throughout the specialty metals industry to cast large alloy ingots. A reduced-order model of the growing and solidifying ingot was developed specifically for dynamic control and estimation of the depth of molten liquid pool atop the ingot in a VAR process. This model accounts only for the thermal aspects of the system ignoring high-fidelity physics such as fluid flow and electromagnetic effects. Spectral methods were used to obtain a set of nonlinear dynamic equations which capture the transient characteristics of liquid pool shape variations around a quasi-steady operating condition. These nonlinear equations are then linearized about this operating condition and further simplified by suppressing fast modes. The resulting system can be described by only six state variables. The reduced order model compares favorably to pool depth changes predicted by an accurate finite-volume model. A first approach to use this model in the design of a dynamic VAR pool depth estimator and controller is also proposed.

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Controlling Liquid Pool Depth in VAR of a 21.6 cm Diameter Ingot of Alloy 718

Proceedings of the 2013 International Symposium on Liquid Metal Processing and Casting ◽

10.1002/9781118830857.ch36 ◽

2013 ◽

pp. 245-252

Author(s):

Felipe Lopez ◽

Joseph Beaman ◽

Rodney Williamson ◽

Eric Taleff ◽

Trevor Watt

Keyword(s):

Liquid Pool ◽

Alloy 718 ◽

Pool Depth ◽

Diameter Ingot

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Investigation on the Steady Thermal Resistance of Axial Grooved Heat Pipe (AGHP)

ASME 2008 First International Conference on Micro/Nanoscale Heat Transfer, Parts A and B ◽

10.1115/mnht2008-52021 ◽

2008 ◽

Author(s):

Hanzhong Tao ◽

Hong Zhang ◽

Jun Zhuang

Keyword(s):

Thermal Resistance ◽

Heat Pipe ◽

Contact Point ◽

Liquid Pool ◽

Force Balance ◽

Working Fluid ◽

Radius Of Curvature ◽

Two Dimensional ◽

Pool Depth ◽

Contact Type

According to the classic thermal resistance network model of the heat pipe, a quasi-two-dimensional theoretical thermal resistance model for the horizontal axial grooved heat pipe (AGHP) under normal conditions is presented. The contact type between liquid working fluid and groove wall at various axial positions are considered. The two-dimensional mass balance equation and momentum equation are adopted to predict the contact type between liquid working fluid and groove wall, contact point position and the radius of curvature of liquid pool. For the condensate thickness and liquid pool depth, three cases are discussed. The liquid pool depth and circumference radius of curvature of each element along the axial direction can be obtained based on the force balance. The elemental thermal resistance is obtained by superposing the compound layer thermal resistance of liquid working fluid and wick, and conductivity thermal resistance of container wall. Paralleling connection the element thermal resistance at the evaporator and the condenser of the AGHP respectively, the thermal resistance of evaporator and condenser are obtained respectively. The overall thermal resistance of the AGHP can be gotten by adding the two parts thermal resistance. The filling amount of working fluid is the sum of vapor and liquid inner the AGHP. The amount of liquid working fluid is the sum of each element in all the grooves. The results from the model are matched the testing results and the traditional semi-empirical correlation.

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Symmetry breaking in convergent-beam diffraction

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100154378 ◽

1989 ◽

Vol 47 ◽

pp. 480-481

Author(s):

D.J. Eaglesham

Keyword(s):

Symmetry Breaking ◽

Point Group ◽

X Ray Diffraction ◽

Multiple Diffraction ◽

Space Groups ◽

Atomic Displacements ◽

Small Probe ◽

Phase Sensitive ◽

Convergent Beam

Convergent Beam Electron Diffraction is now almost routinely used in the determination of the point- and space-groups of crystalline samples. In addition to its small-probe capability, CBED is also postulated to be more sensitive than X-ray diffraction in determining crystal symmetries. Multiple diffraction is phase-sensitive, so that the distinction between centro- and non-centro-symmetric space groups should be trivial in CBED: in addition, the stronger scattering of electrons may give a general increase in sensitivity to small atomic displacements. However, the sensitivity of CBED symmetry to the crystal point group has rarely been quantified, and CBED is also subject to symmetry-breaking due to local strains and inhomogeneities. The purpose of this paper is to classify the various types of symmetry-breaking, present calculations of the sensitivity, and illustrate symmetry-breaking by surface strains.CBED symmetry determinations usually proceed by determining the diffraction group along various zone axes, and hence finding the point group. The diffraction group can be found using either the intensity distribution in the discs

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Centrosome Aurora A gradient ensures single polarity axis in C. elegans embryos

Biochemical Society Transactions ◽

10.1042/bst20200298 ◽

2020 ◽

Vol 48 (3) ◽

pp. 1243-1253 ◽

Cited By ~ 1

Author(s):

Sukriti Kapoor ◽

Sachin Kotak

Keyword(s):

Symmetry Breaking ◽

Cell Fate ◽

Cell Cortex ◽

Axis Formation ◽

Aurora A Kinase ◽

Aurora A ◽

C Elegans ◽

Cell Embryo ◽

Polarity Establishment

Cellular asymmetries are vital for generating cell fate diversity during development and in stem cells. In the newly fertilized Caenorhabditis elegans embryo, centrosomes are responsible for polarity establishment, i.e. anterior–posterior body axis formation. The signal for polarity originates from the centrosomes and is transmitted to the cell cortex, where it disassembles the actomyosin network. This event leads to symmetry breaking and the establishment of distinct domains of evolutionarily conserved PAR proteins. However, the identity of an essential component that localizes to the centrosomes and promotes symmetry breaking was unknown. Recent work has uncovered that the loss of Aurora A kinase (AIR-1 in C. elegans and hereafter referred to as Aurora A) in the one-cell embryo disrupts stereotypical actomyosin-based cortical flows that occur at the time of polarity establishment. This misregulation of actomyosin flow dynamics results in the occurrence of two polarity axes. Notably, the role of Aurora A in ensuring a single polarity axis is independent of its well-established function in centrosome maturation. The mechanism by which Aurora A directs symmetry breaking is likely through direct regulation of Rho-dependent contractility. In this mini-review, we will discuss the unconventional role of Aurora A kinase in polarity establishment in C. elegans embryos and propose a refined model of centrosome-dependent symmetry breaking.

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