Search results for "DAMP"

Analysis of Torque Developed in Axial Flux, Single-Phase Brushless DC Motor With Salient-Pole Stator

2004

An analysis of the torque developed by a single-phase disc brushless permanent magnet motor with salient-pole stator is presented. The machine represents a new family of brushless disc motors with the starting torque issue appearing to be most challenging. To produce a starting torque, the permanent magnets on one of the rotor discs are distributed nonuniformly. However, this significantly distorts a shape of the cogging torque versus rotational angle characteristic which, in turn, affects a waveform of the overall torque. A three-dimensional (3-D) finite-element model is used for the purpose of determining of angular variations of the torque developed by the motor. To find how the torque v…

Innovative modeling of Tuned Liquid Column Damper motion

2015

Abstract In this paper a new model for the liquid motion within a Tuned Liquid Column Damper (TLCD) device is developed, based on the mathematical tool of fractional calculus. Although the increasing use of these devices for structural vibration control, it is shown that existing model does not always lead to accurate prediction of the liquid motion. A better model is then needed for accurate simulation of the behavior of TLCD systems. As regards, it has been demonstrated how correctly including the first linear liquid sloshing mode, through the equivalent mechanical analogy well established in literature, produces numerical results that highly match the corresponding experimental ones. Sin…

Non-local stiffness and damping models for shear-deformable beams

2013

This paper presents the dynamics of a non-local Timoshenko beam. The key assumption involves modeling non-local effects as long-range volume forces and moments mutually exerted by non-adjacent beam segments, that contribute to the equilibrium of any beam segment along with the classical local stress resultants. Elastic and viscous long-range volume forces/moments are endowed in the model. They are built as linearly depending on the product of the volumes of the interacting beam segments and on generalized measures of their relative motion, based on the pure deformation modes of the beam. Attenuation functions governing the space decay of the non-local effects are introduced. Numerical resul…

Theoretical and experimental behaviour of the muscle viscosity coefficient during maximal concentric actions

1994

The aim of this study was to calculate the theoretical variation of the nonlinear damping factor (B) as a function of the muscle shortening velocity, and then to compare the theoretical values with the experimental data obtained on both the elbow flexor and the ankle extensor muscles. The theoretical variation of the B factor was determined from a muscle model consisting of a contractile component in parallel with a viscous damper both in series with an elastic component, and by using, the characteristic equation of the force velocity curve. In this muscle model, the viscous element modelled the inability of the muscle to generate as big a contracting force (while shortening) as possible un…

Stochastic seismic analysis of structures with nonlinear viscous dampers

2007

Fluid damper devices inserted in buildings or bridges are commonly used as energy sinks for seismic protection. In the response analysis of structures with filled damper devices the main problem exists in the strong nonlinear behavior of such equipment, as a consequence the differential equation of motion remains nonlinear and the response spectrum analysis still cannot be applied. In this note, by using the concept of power spectral density function coherent with the elastic response spectrum and by using the statistical linearization technique, expressions for finding the equivalent linear damping have been found. Comparisons with results obtained by Monte Carlo simulations confirm that f…

An investigation of the influence of the macroscopic heterogeneity on the thermoelstic response of fibre reinforced plastics

2005

In this work the influence of the inherent heterogeneity in fibre reinforced plastic composites on the qualitative and quantitative evaluation of the thermoelastic signal is discussed. The role of two different levels of heterogeneity is identified, distinguishing between a micro-geometric scale characterized by the presence of different constituent materials, and a macro-geometric scale characterized by a non-uniform distribution of these constituents. Attention has been focused on the macro-scale level, presenting results of experiments performed on glass fibre - polyester resin samples, intended to highlight the influence on the thermoelastic signal of the fabric texture pattern and the …

A no-go result for the quantum damped harmonic oscillator

2019

Abstract In this letter we show that it is not possible to set up a canonical quantization for the damped harmonic oscillator using the Bateman Lagrangian. In particular, we prove that no square integrable vacuum exists for the natural ladder operators of the system, and that the only vacua can be found as distributions. This implies that the procedure proposed by some authors is only formally correct, and requires a much deeper analysis to be made rigorous.

Entanglement Theory with Continuous Variables

2016

Quantum fluctuations and coherence in high-precision single-electron capture.

2012

The phase of a single quantum state is undefined unless the history of its creation provides a reference point. Thus quantum interference may seem hardly relevant for the design of deterministic single-electron sources which strive to isolate individual charge carriers quickly and completely. We provide a counterexample by analyzing the non-adiabatic separation of a localized quantum state from a Fermi sea due to a closing tunnel barrier. We identify the relevant energy scales and suggest ways to separate the contributions of quantum non-adiabatic excitation and backtunneling to the rare non-capture events. In the optimal regime of balanced decay and non-adiabaticity, our simple electron tr…

Experimental determination of viscous damper parameters in low velocity ranges

2017

In the last decades many strategies for seismic vulnerability mitigation of structures have been developed through analytical studies and experimental tests. Among these, energy dissipation by external devices assumes a great relevance for the relative design simplicity, even if applied to complex structures, and the effectiveness in reducing seismic demand. In particular, the use of fluid viscous dampers represents a very attractive solution because of their velocity-dependent behaviour and relatively low costs. The application on structures requires specific study under seismic excitation and a particular care of structural details. In this context the use of proper constitutive models fo…