Sharif Digital Repository

The effects of the entanglement of the inflaton field which initially entangled with those of another field on observables like power spectrum are known in the context of the Schrödinger field theory. To clarify this effect in the Heisenberg picture, there were some attempts to construct the initial entangled state by making use of an entangled transformation (like Bogoliubov transformation) between the Bunch-Davies vacuums and squeezed states. We study the role of the time-dependent entangled transformation in the Schrödinger field theory. We derive the relation between two vacuum states which their mode functions are transformed by the entangled transformation in Schrödinger picture. We... 

In this paper, a novel analytical approximation to the nonlinear Duffing-harmonic oscillator is presented. The variational iteration method (VIM) is used to obtain some accurate analytical results for frequency. The accuracy of the results is excellent in the whole range of oscillation amplitude variations. © 2009 Elsevier Ltd. All rights reserved  

In the presence of interactions the frequency of a simple harmonic oscillator deviates from the noninteracting one. Various methods can be used to compute the changes to the frequency perturbatively. Some of them resemble the methods used in quantum field theory (QFT) where the bare values of the parameters of the theory run when an interaction is added. In this paper, we review some of these techniques and introduce some new ones in line with QFT methods. Moreover, we investigate the case of more than one oscillator to see how the frequencies of small oscillations change when non-linear terms are added to a linear system and observe an interesting beat phenomenon in degenerate coupled... 

We examine the olfactory discrimination of left- and right-handed enantiomers of chiral odorants based on the odorant-mediated electron transport from a donor to an acceptor of the olfactory receptors embodied in a biological environment. The chiral odorant is effectively described by an asymmetric double-well potential whose minima are associated to the left- and right-handed enantiomers. The introduced asymmetry is considered an overall measure of chiral interactions. The biological environment is conveniently modeled as a bath of harmonic oscillators. The resulting spin-boson model is adapted by a polaron transformation to derive the corresponding Born-Markov master equation with which we... 

In this paper, a new technique based on nonlinear resonance of microbubbles is investigated in order to estimate the amplitude of an ultrasound wave pressure field. First, the existing theoretical model is reviewed. Then, an experimental setup consisting of a bubble generator and transmitting/receiving ultrasound transducers operating in the 1 MHz frequency range is described. The effect of background noise is also taken into account. Results show that the second harmonic oscillations are detectable, paving the way to develop a quantitative method for in vivo calibration of ultrasound waves  

Multiple co-axial heave plates of uniform geometry are attached to offshore platforms for inducing damping and added mass. These effects generally decrease the magnitude of the dynamic response of the platform under applied environmental excitation forces. When spacing between heave plates is decreased the damping and added mass performance are altered due to their strong vortex interaction. A new non-uniform plate configuration is proposed that may create different hydrodynamic characteristics. The modes of vortex shedding around plate edges in a non-uniform arrangement under forced harmonic oscillation are investigated via the CFD method. Furthermore, a new simplified formula for the total... 

Multiple co-axial heave plates of uniform geometry are attached to offshore platforms for inducing damping and added mass. These effects generally decrease the magnitude of the dynamic response of the platform under applied environmental excitation forces. When spacing between heave plates is decreased the damping and added mass performance are altered due to their strong vortex interaction. A new non-uniform plate configuration is proposed that may create different hydrodynamic characteristics. The modes of vortex shedding around plate edges in a non-uniform arrangement under forced harmonic oscillation are investigated via the CFD method. Furthermore, a new simplified formula for the total... 

Multiple co-axial heave plates of uniform geometry are attached to offshore platforms for inducing damping and added mass. These effects generally decrease the magnitude of the dynamic response of the platform under applied environmental excitation forces. When spacing between heave plates is decreased the damping and added mass performance are altered due to their strong vortex interaction. A new non-uniform plate configuration is proposed that may create different hydrodynamic characteristics. The modes of vortex shedding around plate edges in a non-uniform arrangement under forced harmonic oscillation are investigated via the CFD method. Furthermore, a new simplified formula for the total... 

Sloshing, or liquid free surface oscillation, in containers has many important applications in a variety of engineering fields. The modal method can be used to solve linear sloshing problems and is the most efficient reduced order method that has been used during the previous decade. In the present article, the modal method is used to solve a nonlinear sloshing problem. The method is based on a potential flow solution that implements a two-phase analysis on sloshing in a rectangular container. According to this method, the solution to the mass conservation equation, with a nonpenetration condition at the tank walls, results in velocity potential expansion; this is similar to the mode shapes...