scholarly journals Frequency Variation of the AC Order Parameter Susceptibility of the Metamagnetic Ising Model

2018 ◽  
Vol 2018 ◽  
pp. 1-12
Author(s):  
Gul Gulpinar
Keyword(s):  
Order Parameter ◽  
Relaxation Times ◽  
Rate Coefficients ◽  
Irreversible Processes ◽  
Frequency Variation ◽  
Iron Group ◽  
Extensive Investigation ◽  
Field Frequency ◽  
Step Process ◽  
Onsager Theory

The extensive investigation of the absorptive and reactive parts of the AC order parameter susceptibility spectra of iron group dihalides, which is obtained on the basis of Onsager theory of irreversible processes, revealed the fact that the diagonal phenomenological rate coefficients γs and γm have an important impact on the nature of the order parameter relaxation process. The number of the relaxation peaks appearing in the double logarithmic plots of χs′′ versus field frequency ω and the number of plateau regions in χs′ spectrum depends on the values of γs and γm. Only for γs≫γm does the relaxation evolve from a simple Debye exponential at high temperatures to a two-step process at lower temperatures in which there exist two long relaxation times characterizing the relaxation of staggered magnetization. In parallel with these characteristics of the order parameter relaxation, Cole-Cole plots (χs′′-χs′) are shown to consist of two arcs in the metamagnetic phase and of a semicircle in the paramagnetic phase.

Reaktionskinetik des Energietransportes zwischen Rekombinationszentren von Elektroluminophoren

1965 ◽  
Vol 20 (12) ◽  
pp. 1648-1654 ◽  
Author(s):  
I. Broser ◽  
H.-E. Gumlich ◽  
R. Moser
Keyword(s):  
Valence Band ◽  
Luminescence Quenching ◽  
Iron Group ◽  
Field Frequency ◽  
Kinetics Of ◽  
Good Agreement

The kinetics of holes in electroluminescence has been calculated by means of simple two- and three-level-models. As a result an equation is given which describes the ratio of intensity of different emission bands and the degree of luminescence quenching by iron group elements as a function of field frequency and temperature. The calculated curves are in good agreement with the values observed in ZnS containing Cu, Mn, Fe, Co, Ni respectively. The kinetics has been used to calculate the energetic separation of acceptor levels from the valence band and other constants.

scholarly journals The calculation of TV, VT, VV, VV' − rate coefficients for the collisions of the main atmospheric components

1998 ◽  
Vol 16 (7) ◽  
pp. 838-846 ◽  
Author(s):  
A. S. Kirillov
Keyword(s):  
Experimental Data ◽  
Energy Transfer ◽  
Vibrational Energy ◽  
Relaxation Times ◽  
Atmospheric Composition ◽  
Rate Coefficients ◽  
Frequency Change ◽  
Vibrational Energy Transfer ◽  
Ion Chemistry ◽  
Vibrationally Excited

Abstract. The first-order perturbation approximation is applied to calculate the rate coefficients of vibrational energy transfer in collisions involving vibrationally excited molecules in the absence of non-adiabatic transitions. The factors of molecular attraction, oscillator frequency change, anharmonicity, 3-dimensionality and quasiclassical motion have been taken into account in the approximation. The analytical expressions presented have been normalized on experimental data of VT-relaxation times in N2 and O2 to obtain the steric factors and the extent of repulsive exchange potentials in collisions N2-N2 and O2-O2. The approach was applied to calculate the rate coefficients of vibrational-vibrational energy transfer in the collisions N2-N2, O2-O2 and N2-O2. It is shown that there is good agreement between our calculations and experimental data for all cases of energy transfer considered.Key words. Ionosphere (Auroral ionosphere; ion chemistry and composition). Atmospheric composition and structure (Aciglow and aurora).

Dielectric Studies of 4-w-Hexyloxy-4’-Cyanobiphenyl (60CB) at Elevated Pressure

1999 ◽  
Vol 54 (6-7) ◽  
pp. 365-369 ◽  
Author(s):  
S. Urban ◽  
M. Smoluchowski
Keyword(s):  
Dielectric Permittivity ◽  
Order Parameter ◽  
Nematic Phase ◽  
Activation Volume ◽  
Activation Enthalpy ◽  
Ambient Pressure ◽  
Relaxation Times ◽  
Elevated Pressure ◽  
Dielectric Anisotropy ◽  
Dielectric Studies

Abstract The principal dielectric permittivity components in the nematic phase of 4-rc-hexyloxy-4’-cyanobiph-enyl (60CB) were measured as functions of temperature at ambient pressure and as functions of pres-sure up to 100 MPa at several constant temperatures. The dielectric anisotropy is analized in the frame of the Maier-Meier equations. The pressure dependence of the order parameter is deduced. Preliminary results for the activation volume and activation enthalpy from the pressure and temperature dependenc-es of the longitudinal relaxation times are obtained.

A Dissipative Particle Dynamics Study of Liquid Crystals Under Electric Field

2013 ◽  
Author(s):  
Man Prakash Gupta ◽  
Satish Kumar
Keyword(s):  
Liquid Crystals ◽  
Electric Field ◽  
Response Time ◽  
Dynamic Behavior ◽  
Order Parameter ◽  
Dissipative Particle Dynamics ◽  
Critical Value ◽  
Particle Dynamics ◽  
Field Frequency ◽  
Ac Field

We study the equilibrium and dynamic behavior of liquid crystals (LCs) under dc and ac electric field using a mesoscopic simulation technique, Dissipative Particle Dynamics (DPD). We quantify the reorientation of LC molecules and the change in their anisotropic character under external perturbation by an order parameter. We find that the electric field magnitude has to be above a critical value to initiate the reorientation of the director of the LC system along the applied electric field, which is consistent with the experimental observations. The response time of the reorientation process decreases as the magnitude of the electric increases for the dc fields. The effect of ac field frequency on the order parameter is correlated with the field amplitude. The cyclic variation in the order parameter follows the ac field when the oscillation period is greater than the response time of the system and the amplitude is greater than the critical value. Results suggest that the DPD technique can provide important insights in to the dynamic behavior of LC system under both dc and ac electric fields. This technique can further be applied to examine the properties of colloidal LCs which can be very useful for many practical applications.

ENTANGLEMENT CONTROLLING OF A THREE-LEVEL CASCADE ATOM INTERACTING WITH A TIME-DEPENDENT COHERENT FIELD

2009 ◽  
Vol 07 (04) ◽  
pp. 771-794 ◽  
Author(s):  
SHUANGYUAN XIE ◽  
FEI JIA ◽  
YAPING YANG
Keyword(s):  
Frequency Modulation ◽  
Great Influence ◽  
Atomic Level ◽  
Time Dependent ◽  
Frequency Variation ◽  
Time Varying ◽  
Field Frequency ◽  
Coherent Field ◽  
Time Varying Frequency ◽  
Degree Of Entanglement

The interaction between a three-level cascade atom and an initial coherent field with a time-varying frequency has been investigated, including the dynamic behavior of the atomic level occupation probabilities and the entanglement between the atom and the field. The frequency of the field is modulated in the forms of sine and rectangle. It is found that the field-frequency variation has a great influence on the properties of the generalized Jaynes-Cummings model. Appropriate frequency modulation can enhance and stabilize the degree of entanglement between the atom and the field.

Calculation of the order-parameter relaxation times in superconducting aluminum

1978 ◽  
Vol 18 (3) ◽  
pp. 1154-1161 ◽  
Author(s):  
W. E. Lawrence ◽  
A. B. Meador
Keyword(s):  
Order Parameter ◽  
Relaxation Times

Recovery of the resonance frequency of buildings following strong seismic deformation as a proxy for structural health

2019 ◽  
Vol 18 (5-6) ◽  
pp. 1966-1981 ◽  
Author(s):  
Ariana Lucia Astorga ◽  
Philippe Guéguen ◽  
Jacques Rivière ◽  
Toshihide Kashima ◽  
Paul Allan Johnson
Keyword(s):  
Structural State ◽  
Relaxation Times ◽  
Mechanical Damage ◽  
Recovery Process ◽  
Frequency Variation ◽  
Slow Recovery ◽  
Engineering Structures ◽  
Structural Health ◽  
Real Earthquake ◽  
Seismic Deformation

Elastic properties of civil engineering structures change when subjected to a dynamic excitation. The modal frequencies show a rapid decrease followed by a relaxation, or slow recovery, that is dependent on the level of damage. In this article, we analyze the slow recovery process applying three relaxation models to fit real earthquake data recorded in a Japanese building that shows variant structural state over 20 years. Despite the differences in conditions, the different scales and the complexity of a real-scale problem, the models originally developed for laboratory experiments are well adapted to real building data. The relaxation parameters (i.e. frequency variation, recovery slope, characteristic times and their amplitudes, and range of relaxation times) are able to characterize the structural state, given their clear connection to the degree of fracturing and mechanical damage to the building. The recovery process following strong seismic deformation, could, therefore, be a suitable proxy to monitor structural health.

On the derivation of the nematic order parameter from the dielectric relaxation times

1999 ◽  
Vol 1 (11) ◽  
pp. 2787-2791 ◽  
Author(s):  
Stanisław Urban ◽  
Albert Würflinger ◽  
Bo Gestblom
Keyword(s):  
Dielectric Relaxation ◽  
Order Parameter ◽  
Relaxation Times ◽  
Nematic Order

Evolution of the Field Entropy and Preparation of Quantum States in the Control of Atomic Motion and Fieldfrequency Variation

2011 ◽  
Vol 40 (3) ◽  
pp. 458-465
Author(s):  
刘小娟 LIU Xiaojuan ◽  
刘一曼 LIU Yiman ◽  
刘敏 LIU Min
Keyword(s):  
Quantum States ◽  
Atomic Motion ◽  
Frequency Variation ◽  
Field Frequency

Oxygen vibrational and dissociation relaxation behind regular reflected shocks

1976 ◽  
Vol 74 (3) ◽  
pp. 477-495 ◽  
Author(s):  
H. Oertel
Keyword(s):  
Theoretical Model ◽  
Vibrational Relaxation ◽  
Relaxation Times ◽  
Dissociation Rate ◽  
Numerical Calculations ◽  
Rate Coefficients ◽  
Double Exposure ◽  
Experimental Conditions ◽  
Density Profiles ◽  
Best Fit

The oxygen vibrational and dissociation relaxation behind regular reflected shocks has been calculated and measured. Numerical calculations using published rate coefficients supplied the relaxation-zone data needed to estimate the range of most useful experimental conditions. Then photographs of the shock reflexion were taken using a complementary double-exposure interferometer. The density profiles in the relaxation zones behind the reflected shocks were measured by means of a multibeam laser-differential interferometer. The results of these experiments confirmed the theoretical model adopted for the calculations within a certain range of experimental conditions, but clearly revealed the need for revising the rate coefficients. New calculations with different vibrational relaxation times and dissociation rate coefficients then had the result that the best fit of calculated to measured profiles was obtained when the following values were inserted.Vibration\begin{eqnarray*} & p\tau_v = A_v\exp(B_vT^{-\frac{1}{3}}),\\ & A_v = (2.1\pm 0.2)\times 10^{-5}\,{\rm kg/ms},\quad B_v = 129\,{}^{\circ}{\rm K}^{\frac{1}{3}}. \end{eqnarray*}Dissociation: O2+ O_2[rlarr ] 2O + O_2\begin{eqnarray*} & {\mathop {k_1}\limits^{\rightharpoonup}} = A_1T^{-2.5}\exp (-\theta_D/T),\\ & A_1 = (6.2 \pm 0.5)\times 10^{18}\,{\rm m}^3\,{}^{\circ}{\rm K}^{2.5}/{\rm mol}\,{\rm s},\quad\theta_D = 59\,136\,{}^{\circ}{\rm K}. \end{eqnarray*}Dissociation: O2+ O[rlarr ]3O\begin{eqnarray*} & {\mathop {k_1}\limits^{\rightharpoonup}} = A_2T^{-1.0}\exp (-\theta_D/T),\\ & A_2 = (4.0 \mp 0.5)\times 10^{-13}\,{\rm m}^3\,{}^{\circ}{\rm K}/{\rm mol}\,{\rm s}. \end{eqnarray*}

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