Search results for "Damped"
showing 10 items of 19 documents
Acute effects of cold pack on mechanical properties of the quadriceps muscle in healthy subjects.
2012
Purpose: To examine the effects of local cooling on mechanical properties of the quadriceps muscle in healthy subjects. Subjects: Thirty-nine healthy subjects (27 women, 12 men, mean age 39, range 20e62) volunteered. Methods: A cold gel pack was applied to the quadriceps muscle for 20 min. Properties were quantified by analyzing the frequency (tension), decrement (elasticity) and stiffness of damped oscillations and the compliance of the muscle before, immediately after and after 15-min after cooling. Results: The largest responses immediately after cooling were seen in the oscillation decrement parameter, 7.9 (3.7e12.1) %, and in the compliance parameter, � 7.5 (� 9.8 to � 5.3) %. Response…
Solving fully randomized higher-order linear control differential equations: Application to study the dynamics of an oscillator
2021
[EN] In this work, we consider control problems represented by a linear differential equation assuming that all the coefficients are random variables and with an additive control that is a stochastic process. Specifically, we will work with controllable problems in which the initial condition and the final target are random variables. The probability density function of the solution and the control has been calculated. The theoretical results have been applied to study, from a probabilistic standpoint, a damped oscillator.
Generalization of the Den Hartog model and rule-of-thumb formulas for optimal tuned mass dampers
2022
In recent years, the need of improving safety standards for both existing and new buildings against earthquake and wind loads has created a growing interest in the use of the so-called tuned mass dampers, exploited to control, in active or passive way, the dynamic response of structures. To design and optimize tuned mass damper systems, the effective analytical procedure proposed by Den Hartog in his seminal work (Den Hartog, 1985) has been widely adopted over the years, without including damping of the main structure. However, in many cases of engineering interest, the damping of the primary system plays a key role in the overall mechanical response, with the result of an increase in compl…
Numerical investigation of optical heartbeats with external driving forces
2010
The role of harmonic and random external forces in a phenomenological nonlinear model of optical heartbeats is investigated. External forces trigger damped oscillations at the natural frequency of the system and higher harmonics. The numerical results are compared with experimental ones.
Gaussian models for the distribution of Brownian particles in tilted periodic potentials
2011
We present two Gaussian approximations for the time-dependent probability density function (PDF) of an overdamped Brownian particle moving in a tilted periodic potential. We assume high potential barriers in comparison with the noise intensity. The accuracy of the proposed approximated expressions for the time-dependent PDF is checked with numerical simulations of the Langevin dynamics. We found a quite good agreement between theoretical and numerical results at all times.
Transportation-cost inequality on path spaces with uniform distance
2008
Abstract Let M be a complete Riemannian manifold and μ the distribution of the diffusion process generated by 1 2 ( Δ + Z ) where Z is a C 1 -vector field. When Ric − ∇ Z is bounded below and Z has, for instance, linear growth, the transportation-cost inequality with respect to the uniform distance is established for μ on the path space over M . A simple example is given to show the optimality of the condition.
Some remarks on few recent results on the damped quantum harmonic oscillator
2020
Abstract In a recent paper, Deguchi et al. (2019), the authors proposed an analysis of the damped quantum harmonic oscillator in terms of ladder operators. This approach was shown to be partly incorrect in Bagarello et al. (2019), via a simple no-go theorem. More recently, (Deguchi and Fujiwara, 2019), Deguchi and Fujiwara claimed that our results in Bagarello et al. (2019) are wrong, and compute what they claim is the square integrable vacuum of their annihilation operators. In this brief note, we show that their vacuum is indeed not a vacuum, and we try to explain what is behind their mistakes in Deguchi et al. (2019) and Deguchi and Fujiwara (2019). We also propose a very simple example …
Misbeliefs and misunderstandings about the non-Markovian dynamics of a damped harmonic oscillator
2003
We use the exact solution for the damped harmonic oscillator to discuss some relevant aspects of its open dynamics often mislead or misunderstood. We compare two different approximations both referred to as Rotating Wave Approximation. Using a specific example, we clarify some issues related to non--Markovian dynamics, non--Lindblad type dynamics, and positivity of the density matrix.
Effects of neutron richness on the behavior of nuclear systems at intermediate energies
2012
We discuss results concerning the behavior of hot nuclear sources formed in 40 ,48Ca+40 ,48Ca reactions at 25 MeV/nucleon. A correlation between the neutron-to-proton ratio of the total systems and heavy residue production is found. This correlation underlines the strong role played by the neutron-to-proton ratio degree of freedom on the behavior of hot nuclei at intermediate energies. Comparisons of our data with Constrained Molecular Dynamics calculations confirm that a moderately stiff behavior of the symmetry potential must be used to reproduce experimental data. These findings open the way for future investigations with exotic beams at radioactive ion beam facilities. © 2012 American P…
Large Time Behavior for Inhomogeneous Damped Wave Equations with Nonlinear Memory
2020
We investigate the large time behavior for the inhomogeneous damped wave equation with nonlinear memory ϕtt(t,&omega