Time-dependent numerical modelling of hydroxyl masers

2017 ◽  
Vol 13 (S336) ◽  
pp. 59-60
Author(s):  
J. P. Maswanganye ◽  
D. J. van der Walt ◽  
S. Goedhart
Keyword(s):  
Numerical Modelling ◽  
Temperature Variation ◽  
Time Dependent ◽  
Rate Equations ◽  
Temperature Variations ◽  
Dust Temperature ◽  
One To One ◽  
Hydroxyl Masers

AbstractThe statistical rate equations are used to model the OH masers to see if they will always have a one-to-one correspondence with the variation of dust temperature. It is concluded that one has to be careful to argue that the masers will always follow the dust temperature variation profile, and it is possible that different maser transitions from the same molecule respond differently to the same dust temperature variations.

Relaxation times obtained from the rate equations using path probability method for the spin-1 Ising model

2019 ◽  
Vol 33 (22) ◽  
pp. 1950258 ◽  
Author(s):  
Rıza Erdem ◽  
Songül Özüm
Keyword(s):  
Ising Model ◽  
Relaxation Times ◽  
Phenomenological Theory ◽  
Equilibrium States ◽  
Time Dependent ◽  
Rate Equations ◽  
Probability Method ◽  
Temperature Variations ◽  
Path Probability Method ◽  
Good Agreement

We have presented the time-dependent behaviors of a spin-1 Ising model (with both bilinear and biquadratic interactions) in the neighborhood of the equilibrium states via the path probability method. The rate equations as introduced by Keskin and co-workers (1989) have been linearized to obtain the characteristic relaxation times. The temperature variations of these times were produced in accordance with the Tanaka and Mannari’s work (1976) on the equilibrium properties. Results are compared to one using Onsager’s phenomenological theory and a good agreement is achieved.

On the effects of thermal properties structure and water bottom temperature variation on temperature gradients in lake sediments

1986 ◽  
Vol 23 (9) ◽  
pp. 1257-1264 ◽  
Author(s):  
K. Wang ◽  
P. Y. Shen ◽  
A. E. Beck
Keyword(s):  
Heat Flow ◽  
Temperature Variation ◽  
Stratified Medium ◽  
Depth Interval ◽  
Flow Density ◽  
Detailed Knowledge ◽  
Bottom Temperature ◽  
Temperature Variations ◽  
Density Values ◽  
Finite Sum

In heat flow determinations, it is customary to treat the surface temperature variation as a finite sum of Fourier components. The medium is assumed to be homogeneous or horizontally stratified with each layer having a constant conductivity and diffusivity. This allows the effect of each periodic component to be calculated analytically. We extend this formulation to include cases where thermal conductivities in some layers of a stratified medium may vary linearly with depth as have been found in the sediments of some continental lakes. The application of this formalism to temperature measurements in Lake Greifensee and Lac Leman shows that even with excellent records of bottom temperature variations over several years, failure to take into account the conductivity variation leads to errors as high as 20% in heat flow density values, depending on the depth interval used. The combined effects of lack of detailed knowledge of conductivity structure and the use of too short and (or) inaccurate records of bottom temperature variations, leading to very significant errors, are also discussed, with particular reference to the problems arising from a lack of recognition of the existence of nonannual terms in the bottom temperature variation and the use of probes that do not penetrate the sediments deeply enough.

scholarly journals On Spatial Evolution of the Solution of a Nonstandard Problem in Linear Thermo-Microstretch Elasticity

2011 ◽  
Vol 2011 ◽  
pp. 1-16
Author(s):  
Emilian Bulgariu
Keyword(s):  
Boundary Conditions ◽  
Temperature Variation ◽  
Exponential Growth ◽  
Heat Supply ◽  
Elastic Cylinder ◽  
Time Dependent ◽  
Infinite Cylinder ◽  
Spatial Evolution ◽  
Alternative Behavior ◽  
Nonstandard Problem

An anisotropic and nonhomogeneous compressible linear thermo-microstretch elastic cylinder is subject to zero body loads and heat supply and zero lateral specific boundary conditions. The motion is induced by a time-dependent displacement, microrotation, microstretch, and temperature variation specified pointwise over the base. Further, the motion is constrained such that the displacement, microrotation, microstretch and temperature variation and their derivatives with respect to time at points in the cylinder and at a prescribed time are given in proportion to, but not identical with, their respective initial values. Two different cases for these proportional constants are treated. It is shown that certain integrals of the solution spatially evolve with respect to the axial variable. Conditions are derived that show that the integrals exhibit alternative behavior and in particular for the semi-infinite cylinder that there is either at least exponential growth or at most exponential decay.

Using time-dependent rate equations to describe chirped pulse excitation in condensed phases

1999 ◽  
Vol 302 (5-6) ◽  
pp. 405-410 ◽  
Author(s):  
Christopher J. Bardeen ◽  
Jianshu Cao ◽  
Frank L.H. Brown ◽  
Kent R. Wilson
Keyword(s):  
Time Dependent ◽  
Rate Equations ◽  
Pulse Excitation ◽  
Condensed Phases ◽  
Chirped Pulse ◽  
Dependent Rate

scholarly journals Effect of Pressure Fluctuations on the Temperature During Braking

2020 ◽  
Vol 14 (2) ◽  
pp. 103-107
Author(s):  
Katarzyna Topczewska ◽  
Przemysław Zamojski
Keyword(s):  
Frictional Heating ◽  
Pressure Fluctuations ◽  
Time Dependent ◽  
Maximum Temperature ◽  
Thermal Problem ◽  
Temperature Variations ◽  
One Dimensional ◽  
Metal Ceramic ◽  
The One ◽  
Calculate Temperature Distribution

AbstractThe aim of this study is to develop the numerical–analytical model of frictional heating in a pad/disc system during braking including the pressure fluctuations, engendered by the pump in an anti-skid braking operation. For this purpose, the problem of motion and the one-dimensional thermal problem of friction for a semi-space/semi-space tribosystem were formulated and solved. Obtained solutions allow to calculate temperature distribution on the contact surface and inside the friction elements. Thermal analysis was performed for a metal–ceramic pad and a cast iron disc during one-time braking including the time-dependent, oscillating pressure. The influence of amplitude of pressure fluctuations on the temperature variations was investigated, especially on the value of maximum temperature achieved during braking.

scholarly journals PENGARUH VARIASI SUHU PENCAMPURAN DAN PEMADATAN AGREGAT BATU PECAH MADURA (DESA ASEM JARAN KECAMATAN BANYUATES KABUPATEN SAMPANG) PADA CAMPURAN ASPAL PANAS (HOTMIX) ASPHALT CONCRETE WEARING COURSE (ACWC), TERHADAP KARAKTERISTIK MARSHALL

2019 ◽  
Vol 4 (1) ◽  
Author(s):  
Taurina Jemmy Irwanto
Keyword(s):  
Temperature Variation ◽  
Asphalt Concrete ◽  
Asphalt Mixture ◽  
Test Method ◽  
Smelting Process ◽  
Density Level ◽  
Compaction Process ◽  
Temperature Variations ◽  
Marshall Test ◽  
Asphalt Content

 AbstractThe mixing temperature has a role in the asphalt smelting process against aggregate, while the compaction temperature has a depth in the density level of the hot asphalt mixture. The better the mixing and compaction process, the better the mixing and compaction process, the better the performance of the asphalt mixture, the better the performance of the asphalt mixture, the better the paved mixture is planned according to the general specifications of Bina Marga 2010. The mixture of mixtures used is Concrete Wearing Course (ACWC). In this study aims to determine the effect of variations in mixing temperature and compaction on the mixture ACWC hot asphalt using broken stone Asem Jaran Distric Banyuates Sampang. Temperature variations used are 160/1460C, 170/1560C, 180/1660C ,  190/1760C  and  200/1860C  with asphalt content 5,2%, 5,7% dan 6,2%. The test uses the Marshall test method by looking for the charcteristic values of Marshall. Based on the results of testing in the laboratory, it was found an increase in the value of Marshall characteristics from variations in temperature 160/1460C to 170/1560C temperature variations and to decrease the test result of Marshall characteristics values at a temperature variation of 180/1660C ,  190/1760C and 200/1860C so that it was concluded that the use of mixing temperature and optimum compaction at a temperature variation of 170/1560C. Keywords: Temperature, Temperature Variation, Marshall Test, Asphalt concrete Wearing Course (ACWC).  

KINETICS OF HYDROGEN ABSORPTION IN Ti600 ALLOY

2009 ◽  
Vol 23 (06n07) ◽  
pp. 863-868 ◽  
Author(s):  
XIAOLI WANG ◽  
YONGQING ZHAO ◽  
WEIDONG ZENG ◽  
HONGLIANG HOU ◽  
YAOQI WANG
Keyword(s):  
Chemical Reaction ◽  
Hydrogen Absorption ◽  
Exothermic Reaction ◽  
Three Dimensional ◽  
Time Dependent ◽  
Reaction Process ◽  
Rate Equations ◽  
Absorption Process ◽  
Reaction Rate Constants ◽  
Hydriding Reaction

The kinetics and mechanism of hydrogen absorption in Ti 600 alloy were investigated at various temperatures (873 K ≤ T ≤ 1123 K ). The rate of hydrogen absorption and equilibrium hydrogen pressure increased with the increase of temperature. Because hydriding reaction is an exothermic reaction, solubility of hydrogen decreased with increasing temperature. The experiment results were interpreted from the time dependent hydrogen absorption curves using various rate equations to reveal the mechanism of the hydrogen absorption processes. The hydriding reaction rate constants were extracted from the time-dependent hydrogen absorption curves. The mechanism of hydriding reaction in different stages has been analyzed. It was found that the chemical reaction process dominated the hydrogen absorption process at 923K. The chemical reaction process and the three-dimensional diffusion process dominated the hydrogen absorption process at 973K or higher.

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