scholarly journals Role of anharmonic phonon scattering in the spectrally decomposed thermal conductance at planar interfaces

2014 ◽  
Vol 90 (13) ◽  
Author(s):  
K. Sääskilahti ◽  
J. Oksanen ◽  
J. Tulkki ◽  
S. Volz
Keyword(s):  
Phonon Scattering ◽  
Thermal Conductance

Lattice Thermal Conductivity Modelling of a Diatomic Nanoscale Material

2020 ◽  
Vol 10 (5) ◽  
pp. 602-609
Author(s):  
Adil H. Awad
Keyword(s):  
Thermal Conductivity ◽  
Lattice Thermal Conductivity ◽  
Phonon Scattering ◽  
Correction Term ◽  
Nanoscale Material ◽  
New Approach ◽  
Two Samples ◽  
Conductivity Modelling ◽  
Callaway Model

Introduction: A new approach for expressing the lattice thermal conductivity of diatomic nanoscale materials is developed. Methods: The lattice thermal conductivity of two samples of GaAs nanobeam at 4-100K is calculated on the basis of monatomic dispersion relation. Phonons are scattered by nanobeam boundaries, point defects and other phonons via normal and Umklapp processes. Methods: A comparative study of the results of the present analysis and those obtained using Callaway formula is performed. We clearly demonstrate the importance of the utilised scattering mechanisms in lattice thermal conductivity by addressing the separate role of the phonon scattering relaxation rate. The formulas derived from the correction term are also presented, and their difference from Callaway model is evident. Furthermore their percentage contribution is sufficiently small to be neglected in calculating lattice thermal conductivity. Conclusion: Our model is successfully used to correlate the predicted lattice thermal conductivity with that of the experimental observation.

Role of hydrogen bonds in thermal conductance at the graphene oxide-H2O interface

2022 ◽  
Vol 183 ◽  
pp. 122125
Author(s):  
Shanchen Li ◽  
Yang Chen ◽  
Zhihui Li ◽  
Junhua Zhao ◽  
Ning Wei
Keyword(s):  
Graphene Oxide ◽  
Hydrogen Bonds ◽  
Thermal Conductance

Thermoregulation, growth, and reproduction in Alaskan collared lemmings: role of short day and cold

1991 ◽  
Vol 261 (3) ◽  
pp. R522-R530 ◽  
Author(s):  
H. A. Maier ◽  
D. D. Feist
Keyword(s):  
Food Intake ◽  
Thermal Conductance ◽  
Reproductive Condition ◽  
Reproductive Morphology ◽  
Short Day ◽  
Long Day ◽  
Dicrostonyx Groenlandicus ◽  
Before And After ◽  
Growth And Reproduction

To assess factors controlling seasonal thermoregulatory and reproductive changes, collared lemmings (Dicrostonyx groenlandicus) were exposed for 16 wk to long day (LD, 22 h light: 2 h dark) and warm (15 +/- 3 degrees C), LD and cold (1 +/- 0.5 degrees C), short day (SD, 4 h light: 20 h dark) and warm, SD and cold or acclimatized to outdoor winter conditions (OUT). Hair length and color, body mass, and food intake were monitored weekly. Resting metabolic rates (RMR) and nonshivering thermogenesis (NST) were estimated several times by measuring oxygen consumption before and after norepinephrine injections. Body composition and reproductive condition were determined at the end of the experiment. SD and OUT groups had a 15.8% lower (P less than 0.01) RMR at 7 degrees C than the LD groups. Lower thermal conductance in SD and OUT animals appears due to molt to white winter pelage, which occurred by week 3 in SD but not in LD groups. Neither SD, cold, nor OUT altered NST or reproductive morphology. SD-exposed lemmings showed 19.2% greater growth than those in LD, resulting primarily from a 29.2 and 15.0% increase in lean and ash components, respectively. Cold exposure increased food intake by 34.7%. Results suggest that the pineal gland, which mediates SD effects, may influence molt and growth but not NST or reproductive morphology.

scholarly journals Energy Balance Approach to Study the Role of Perspiration in Heat Distribution of Human Skin

2020 ◽  
Vol 2020 ◽  
pp. 1-5
Author(s):  
Aijaz Mir ◽  
Ibrahim M. Almanjahie ◽  
Javid Gani Dar
Keyword(s):  
Energy Balance ◽  
Human Skin ◽  
Subcutaneous Tissue ◽  
Thermal Conductance ◽  
Energy Balance Equation ◽  
Heat Radiation ◽  
Fourier Law ◽  
Bioheat Equation ◽  
Energy Balance Approach

This paper develops a model to identify the role of perspiration in temperature distribution of human skin. The model has been solved by using the energy balance equation on the surface of human skin. The role played by thermal conductance, convection, and heat radiation during heat transfer in human skin has been considered, and the relevant laws such as Fourier law for conduction, Newton’s Law for convection, and Stefan–Boltzmann’s law for radiation have been used in the model. Pennes’ bioheat equation has been employed to estimate the heat flow in the dermal region of skin including subcutaneous tissue.

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