scholarly journals Experimental and Theoretical Analysis of Non-linear Vibrational Relaxation of Polyatomic Molecules Strongly Excited by Resonant Laser Radiation

1988 ◽  
Vol 8 (2-4) ◽  
pp. 315-334
Author(s):  
L. Carlomusto ◽  
A. Cartelli ◽  
S. Solimeno ◽  
R. Velotta ◽  
R. Bruzzese
Keyword(s):  
Vibrational Relaxation ◽  
Polyatomic Molecules ◽  
Relaxation Processes ◽  
Molecular Dissociation ◽  
Molecular Gases ◽  
Simple Theoretical Model ◽  
Rough Approximation ◽  
Resonant Laser ◽  
Non Linear ◽  
Made In

We present a very simple theoretical model aimed at the analysis of non-linear relaxation processes in molecular gases in the presence of partial molecular dissociation induced by vibrational–vibrational exchange between highly excited molecules. The model has a phenomenological character, since it analyzes the behavior of a system of anharmonic diatomic molecules, which is a very rough approximation of a polyatomic molecule such as SF6. Nonetheless, it provides an interesting key for the interpretation of a number of peculiar features characterizing our experimental observation, with which a comparison is made. In particular, the model takes realistic account of the influence of dissociation processes on the relaxation time.

Imprecision of Laboratory Determinations and Diagnostic Accuracy: Theoretical Considerations

1974 ◽  
Vol 13 (03) ◽  
pp. 151-158 ◽  
Author(s):  
D. A. B. Lindbebo ◽  
Fr. R. Watson
Keyword(s):  
Mathematical Model ◽  
Diagnostic Accuracy ◽  
Diagnostic Process ◽  
Clinical Laboratories ◽  
Non Linear ◽  
Theoretical Considerations ◽  
Made In

Recent studies suggest the determinations of clinical laboratories must be made more precise than at present. This paper presents a means of examining benefits of improvement in precision. To do this we use a mathematical model of the effect upon the diagnostic process of imprecision in measurements and the influence upon these two of Importance of Diagnosis and Prevalence of Disease. The interaction of these effects is grossly non-linear. There is therefore no proper intuitive answer to questions involving these matters. The effects can always, however, be calculated.Including a great many assumptions the modeling suggests that improvements in precision of any determination ought probably to be made in hospital rather than screening laboratories, unless Importance of Diagnosis is extremely high.

scholarly journals Non-linear dielectric spectroscopy for detecting and evaluating structure-property relations in a P(VDF-TrFE-CFE) relaxor-ferroelectric terpolymer

2021 ◽  
Vol 127 (10) ◽  
Author(s):  
Thulasinath Raman Venkatesan ◽  
David Smykalla ◽  
Bernd Ploss ◽  
Michael Wübbenhorst ◽  
Reimund Gerhard
Keyword(s):  
Dielectric Spectroscopy ◽  
Vinylidene Fluoride ◽  
Paraelectric Phase ◽  
Space Charge Polarization ◽  
Relaxor Ferroelectric ◽  
Relaxation Processes ◽  
Structure Property ◽  
Property Relations ◽  
Non Linear ◽  
Thermally Stimulated Depolarization

AbstractNon-linear dielectric spectroscopy (NLDS) is employed as an effective tool to study relaxation processes and phase transitions of a poly(vinylidenefluoride-trifluoroethylene-chlorofluoroethylene) (P(VDF-TrFE-CFE)) relaxor-ferroelectric (R-F) terpolymer in detail. Measurements of the non-linear dielectric permittivity $${\varepsilon _{2}^{'}}$$ ε 2 ′ reveal peaks at 30 and 80$$\,^\circ$$ ∘ C that cannot be identified in conventional dielectric spectroscopy. By combining the results from NLDS experiments with those from other techniques such as thermally stimulated depolarization and dielectric-hysteresis studies, it is possible to explain the processes behind the additional peaks. The former peak, which is associated with the mid-temperature transition, is found in all other vinylidene fluoride-based polymers and may help to understand the non-zero $$\varepsilon _\mathrm {2}^{'}$$ ε 2 ′ values that are detected on the paraelectric phase of the terpolymer. The latter peak can also be observed during cooling of P(VDF-TrFE) copolymer samples at 100$$\,^\circ$$ ∘ C and is due to conduction and space-charge polarization as a result of the accumulation of real charges at the electrode–sample interface.

Vibrational relaxation in polyatomic molecules: SF6

1973 ◽  
Vol 59 (11) ◽  
pp. 5824-5827 ◽  
Author(s):  
W. D. Breshears ◽  
L. S. Blair
Keyword(s):  
Vibrational Relaxation ◽  
Polyatomic Molecules

On the Non-Linear Dynamics of a Traveling Cable With Small Sag

1995 ◽  
Author(s):  
Christoph G. Reuter ◽  
Peter Hagedorn
Keyword(s):  
Equations Of Motion ◽  
Steady State Solution ◽  
Extended Model ◽  
Transport Velocity ◽  
Non Linear ◽  
Mechanical Models ◽  
Linear Vibrations ◽  
Technical Systems ◽  
Inertia Forces ◽  
Made In

Abstract Traveling cables or threadlines appear in a number of technical applications such as textile machinery, V-belts, ski lifts, funiculars and also in simple models of traveling webs in paper machinery. The mechanical models used so far, most often neglect the effect of sag due to the weight of the cable, although it is well known that in some cases it may be quite important. In this paper, the authors develop a particularly simple model for translating cables using the assumption that the longitudinal inertia forces are negligible in comparison to the transversal inertia forces if the sag of the cable is sufficiently small. This assumption has already been made in a study of linear vibrations of stationary cables in 1970 by Irvine & Caughey. This lead to surprising results which have also been verified experimentally in the laboratory. The extended model presented in this paper includes gyroscopic and nonlinear terms in the equations of motion, related to the cable transport velocity and geometric nonlinearities. As a particular case (zero longitudinal speed and linear theory) the model of Irvine & Caughey is again contained in the present analysis. The linear and non-linear vibrations about a steady state solution are studied. The results show some interesting features which may also be relevant to technical systems if the transport speed is sufficiently high.

Sign in / Sign up

Export Citation Format

Share Document