SIMULATION OF TRANSIENT TWO-DIMENSIONAL RADIATIVE AND CONDUCTIVE HEAT EXCHANGES IN HIGH-TEMPERATURE GLASS

2008 ◽  
Author(s):  
Fatmir Asllanaj ◽  
Laetitia Soudre ◽  
Yves Meshaka
Keyword(s):  
High Temperature ◽  
Conductive Heat ◽  
Two Dimensional ◽  
Heat Exchanges

scholarly journals Investigation of the Heteroepitaxial Process Optimization of Ge Layers on Si (001) by RPCVD

Nanomaterials ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 928
Author(s):  
Yong Du ◽  
Zhenzhen Kong ◽  
Muhammet Toprak ◽  
Guilei Wang ◽  
Yuanhao Miao ◽  
...  
Keyword(s):  
High Temperature ◽  
Buffer Layer ◽  
Layer Thickness ◽  
Growth Temperature ◽  
Crystalline Quality ◽  
Initial Growth ◽  
Two Dimensional ◽  
High Quality ◽  
Reduced Pressure

This work presents the growth of high-quality Ge epilayers on Si (001) substrates using a reduced pressure chemical vapor deposition (RPCVD) chamber. Based on the initial nucleation, a low temperature high temperature (LT-HT) two-step approach, we systematically investigate the nucleation time and surface topography, influence of a LT-Ge buffer layer thickness, a HT-Ge growth temperature, layer thickness, and high temperature thermal treatment on the morphological and crystalline quality of the Ge epilayers. It is also a unique study in the initial growth of Ge epitaxy; the start point of the experiments includes Stranski–Krastanov mode in which the Ge wet layer is initially formed and later the growth is developed to form nuclides. Afterwards, a two-dimensional Ge layer is formed from the coalescing of the nuclides. The evolution of the strain from the beginning stage of the growth up to the full Ge layer has been investigated. Material characterization results show that Ge epilayer with 400 nm LT-Ge buffer layer features at least the root mean square (RMS) value and it’s threading dislocation density (TDD) decreases by a factor of 2. In view of the 400 nm LT-Ge buffer layer, the 1000 nm Ge epilayer with HT-Ge growth temperature of 650 °C showed the best material quality, which is conducive to the merging of the crystals into a connected structure eventually forming a continuous and two-dimensional film. After increasing the thickness of Ge layer from 900 nm to 2000 nm, Ge surface roughness decreased first and then increased slowly (the RMS value for 1400 nm Ge layer was 0.81 nm). Finally, a high-temperature annealing process was carried out and high-quality Ge layer was obtained (TDD=2.78 × 107 cm−2). In addition, room temperature strong photoluminescence (PL) peak intensity and narrow full width at half maximum (11 meV) spectra further confirm the high crystalline quality of the Ge layer manufactured by this optimized process. This work highlights the inducing, increasing, and relaxing of the strain in the Ge buffer and the signature of the defect formation.

Two-Dimensional Transient Heat Transfer Model for High-Temperature Laser-Scanning Confocal Microscopy

2021 ◽  
Author(s):  
Dasith Liyanage ◽  
Suk-Chun Moon ◽  
Ajith S. Jayasekare ◽  
Abheek Basu ◽  
Madeleine Du Toit ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Phase Transformation ◽  
High Temperature ◽  
Laser Scanning ◽  
Laser Scanning Confocal Microscopy ◽  
Transfer Model ◽  
Two Dimensional ◽  
Scanning Confocal Microscopy ◽  
Solid Liquid Interface ◽  
Solid Liquid

Abstract High-temperature laser-scanning confocal microscopy (HT-LSCM) has proven to be an excellent experimental technique through in-situ observations of high temperature phase transformation to study kinetics and morphology using thin disk steel specimens. A 1.0 kW halogen lamp, within the elliptical cavity of the HT-LSCM furnace radiates heat and imposes a non-linear temperature profile across the radius of the steel sample. This local temperature profile when exposed at the solid/liquid interface determines the kinetics of solidification and phase transformation morphology. A two-dimensional numerical heat transfer model for both isothermal and transient conditions is developed for a concentrically solidifying sample. The model can accommodate solid/liquid interface velocity as an input parameter under concentric solidification with cooling rates up to 100 K/min. The model is validated against a commercial finite element analysis software package, Strand7, and optimized with experimental data obtained under near-to equilibrium conditions. The validated model can then be used to define the temperature landscape under transient heat transfer conditions.

Coupled Radiative and Conductive Heat Transfer in a Two-Dimensional Rectangular Enclosure With Gray Participating Media Using Finite Elements

1984 ◽  
Vol 106 (3) ◽  
pp. 613-619 ◽  
Author(s):  
M. M. Razzaque ◽  
J. R. Howell ◽  
D. E. Klein
Keyword(s):  
Heat Transfer ◽  
Flux Distribution ◽  
Conductive Heat Transfer ◽  
Conductive Heat ◽  
Two Dimensional ◽  
The Finite Element Method ◽  
Heat Flux Distribution ◽  
Distributed Energy ◽  
Participating Media ◽  
Rectangular Enclosure

A numerical solution of the exact equations of coupled radiative/conductive heat transfer and temperature distribution inside a medium, and of the heat flux distribution at all the gray walls of a two-dimensional rectangular enclosure with the medium having uniform absorbing/emitting properties, using the finite element method, is presented. The medium can also have distributed energy sources. Comparison is made to the results of the P-3 approximation method.

scholarly journals Variance of Voltages in a Lattice Coulomb Gas

2021 ◽  
Vol 186 (1) ◽  
Author(s):  
Diana Conache ◽  
Markus Heydenreich ◽  
Franz Merkl ◽  
Silke W. W. Rolles
Keyword(s):  
High Temperature ◽  
Symmetry Breaking ◽  
Spontaneous Symmetry Breaking ◽  
Temperature Regime ◽  
Gaussian Model ◽  
Coulomb Gas ◽  
Two Dimensional ◽  
Discrete Gaussian Model ◽  
Dimensional Lattice ◽  
The Difference

AbstractWe study the behavior of the variance of the difference of energies for putting an additional electric unit charge at two different locations in the two-dimensional lattice Coulomb gas in the high-temperature regime. For this, we exploit the duality between this model and a discrete Gaussian model. Our estimates follow from a spontaneous symmetry breaking in the latter model.

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