scholarly journals Temperature oscillation in one-dimensional superlattice induced by phonon localization

2021 ◽  
Author(s):  
Longkai Lu ◽  
Dengke Ma ◽  
Ming Zhong ◽  
Lifa Zhang
Keyword(s):  
Temperature Gradient ◽  
High Frequency ◽  
Temperature Oscillation ◽  
Thermodynamic Quantities ◽  
Localized Modes ◽  
One Dimensional ◽  
Oscillation Phenomenon ◽  
Low Dimensional ◽  
Phonon Localization ◽  
Good Agreement

Abstract Thermal transport properties and thermodynamic quantities often present anomalous behaviors in low-dimensional systems. In this paper, we find that temperature oscillates spatially in one dimensional harmonic and weakly anharmonic superlattice. With the increase of anharmonicity, the temperature oscillation gradually disappears and a normal temperature gradient forms. Further analysis reveals that the formation of temperature oscillation is due to the localization of high frequency phonons which cannot be thermalized. Moreover, the localized modes interact weakly with heat reservoirs, thus, their contributions to local temperature remain negligible while varying the temperatures of heat reservoirs. The oscillated temperature profile is in a good agreement with Visscher's formula. These discoveries of temperature oscillation phenomenon have great potential in applications of phononic devices for heat manipulation.

High-frequency, "quantum" and electromechanical effects in quasi-one-dimensional charge density wave conductors

2013 ◽  
Vol 183 (1) ◽  
pp. 33-54 ◽  
Author(s):  
Vadim Ya. Pokrovskii ◽  
Sergey G. Zybtsev ◽  
Maksim V. Nikitin ◽  
Irina G. Gorlova ◽  
Venera F. Nasretdinova ◽  
...  
Keyword(s):  
Charge Density ◽  
High Frequency ◽  
Charge Density Wave ◽  
Density Wave ◽  
One Dimensional ◽  
Electromechanical Effects

Effect of leakage and blockage on the acoustic behavior of particle filters

2019 ◽  
Vol 67 (6) ◽  
pp. 483-492
Author(s):  
Seonghyeon Baek ◽  
Iljae Lee
Keyword(s):  
Transfer Matrix ◽  
Particle Filters ◽  
Acoustic Analysis ◽  
Transmission Loss ◽  
One Dimensional ◽  
Filter System ◽  
The Difference ◽  
The One ◽  
Analytical Approaches ◽  
Good Agreement

The effects of leakage and blockage on the acoustic performance of particle filters have been examined by using one-dimensional acoustic analysis and experimental methods. First, the transfer matrix of a filter system connected to inlet and outlet pipes with conical sections is measured using a two-load method. Then, the transfer matrix of a particle filter only is extracted from the experiments by applying inverse matrices of the conical sections. In the analytical approaches, the one-dimensional acoustic model for the leakage between the filter and the housing is developed. The predicted transmission loss shows a good agreement with the experimental results. Compared to the baseline, the leakage between the filter and housing increases transmission loss at a certain frequency and its harmonics. In addition, the transmission loss for the system with a partially blocked filter is measured. The blockage of the filter also increases the transmission loss at higher frequencies. For the simplicity of experiments to identify the leakage and blockage, the reflection coefficients at the inlet of the filter system have been measured using two different downstream conditions: open pipe and highly absorptive terminations. The experiments show that with highly absorptive terminations, it is easier to see the difference between the baseline and the defects.

PHOTOINDUCED NONLINEAR OCTUPOLAR POLARIZATION: TRANSIENT AND PERMANENT REGIMES

1996 ◽  
Vol 05 (04) ◽  
pp. 653-670 ◽  
Author(s):  
CÉLINE FIORINI ◽  
JEAN-MICHEL NUNZI ◽  
FABRICE CHARRA ◽  
IFOR D.W. SAMUEL ◽  
JOSEPH ZYSS
Keyword(s):  
Theoretical Analysis ◽  
Second Harmonic ◽  
Experimental Results ◽  
Polar Field ◽  
Rotational Spectrum ◽  
Dual Frequency ◽  
One Dimensional ◽  
Ethyl Violet ◽  
Disperse Red 1 ◽  
Good Agreement

An original poling method using purely optical means and based on a dual-frequency interference process is presented. We show that the coherent superposition of two beams at fundamental and second-harmonic frequencies results in a polar field with an irreducible rotational spectrum containing both a vector and an octupolar component. This enables the method to be applied even to molecules without a permanent dipole such as octupolar molecules. After a theoretical analysis of the process, we describe different experiments aiming at light-induced noncentrosymmetry performed respectively on one-dimensional Disperse Red 1 and octupolar Ethyl Violet molecules. Macroscopic octupolar patterning of the induced order is demonstrated in both transient and permanent regimes. Experimental results show good agreement with theory.

scholarly journals Efficient Numerical Evaluation of Thermodynamic Quantities on Infinite (Semi-)classical Chains

2021 ◽  
Vol 182 (3) ◽  
Author(s):  
Christian B. Mendl ◽  
Folkmar Bornemann
Keyword(s):  
Transfer Operator ◽  
Classical System ◽  
Free Energy Density ◽  
Classical Particle ◽  
Thermodynamic Quantities ◽  
Nls Equation ◽  
Classical Systems ◽  
Particle Chain ◽  
Dynamics Simulations ◽  
Good Agreement

AbstractThis work presents an efficient numerical method to evaluate the free energy density and associated thermodynamic quantities of (quasi) one-dimensional classical systems, by combining the transfer operator approach with a numerical discretization of integral kernels using quadrature rules. For analytic kernels, the technique exhibits exponential convergence in the number of quadrature points. As demonstration, we apply the method to a classical particle chain, to the semiclassical nonlinear Schrödinger (NLS) equation and to a classical system on a cylindrical lattice. A comparison with molecular dynamics simulations performed for the NLS model shows very good agreement.

A Model for Predicting Temperature of Electrofusion Joints for Polyethylene Pipes

2009 ◽  
Vol 131 (6) ◽  
Author(s):  
Jianfeng Shi ◽  
Jinyang Zheng ◽  
Weican Guo ◽  
Ping Xu ◽  
Yongquan Qin ◽  
...  
Keyword(s):  
Thermal Contact ◽  
Power Input ◽  
Ultrasonic Test ◽  
Thermal Contact Conductance ◽  
Transfer Model ◽  
Contact Conductance ◽  
One Dimensional ◽  
Polyethylene Pipes ◽  
Heating Wire ◽  
Good Agreement

With the increasing application of electrofusion (EF) welding in connecting polyethylene (PE) pipes for gas distribution, more effort has been invested to ensure the safety of the pipeline systems. The objective of this paper is to investigate and understand the temperature distribution during EF welding. A one-dimensional transient heat-transfer model was proposed, taking the variation in the rate of power input, the phase transition of PE, and the thermal contact conductance between heating wire and PE into consideration. Then, experiments were designed to verify the power input and the temperature. The measured values of the power input were shown to be in good agreement with the analytical results. Based on ultrasonic test (UT), a new “Eigen-line” method was presented, which overcomes the difficulties found in the thermocouples’ temperature measurements. The results demonstrate good agreements between prediction and experiment. Finally, based on the presented model, a detailed parametric study was carried out to investigate the influences of the variation in the power input, the physical properties of PE, and the thermal contact conductance between heating wire and surrounding PE.

Quantum Criticality and Collective Effects in Low-Dimensional Magnet CuGeO3:Fe Probed by High Frequency EPR

2006 ◽  
Vol 20 (2) ◽  
pp. 105-108 ◽  
Author(s):  
S. V. Demishev ◽  
A. V. Semeno ◽  
A. A. Pronin ◽  
N. E. Sluchanko ◽  
N. A. Samarin ◽  
...  
Keyword(s):  
High Frequency ◽  
Quantum Criticality ◽  
Collective Effects ◽  
Low Dimensional

Global Stability Analysis of the Wake behind a Circular Cylinder Based on the POD-Chiba Method

2011 ◽  
Vol 137 ◽  
pp. 72-76
Author(s):  
Wei Zhang ◽  
Xian Wen ◽  
Yan Qun Jiang
Keyword(s):  
Stability Analysis ◽  
Circular Cylinder ◽  
Global Stability ◽  
Dimensional Model ◽  
Global Stability Analysis ◽  
The Stability ◽  
Low Dimensional ◽  
Proper Orthogonal ◽  
Calculated Amount ◽  
Good Agreement

A proper orthogonal decomposition (POD) method is applied to study the global stability analysis for flow past a stationary circular cylinder. The flow database at Re=100 is obtained by CFD software, i.e. FLUENT, with which POD bases are constructed by a snapshot method. Based on the POD bases, a low-dimensional model is established for solving the two-dimensional incompressible NS equations. The stability of the flow solution is evaluated by a POD-Chiba method in the way of the eigensystem analysis for the velocity disturbance. The linear stability analysis shows that the first Hopf bifurcation takes place at Re=46.9, which is in good agreement with available results by other high-order accurate stability analysis methods. However, the calculated amount of POD is little, which shows the availability and advantage of the POD method.

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