Quantum gravity effect in torsion driven inflation and CP violation

Journal of High Energy Physics - In this paper we study the production of a heavy charged Higgs boson in association with heavy quarks at the LHC in the two-Higgs-doublet model. We present for the...     

Vibration control of a transversely excited cantilever beam with tip mass

The problem of controlling the vibration of a transversely excited cantilever beam with tip mass is analyzed within the framework of the Euler–Bernoulli beam theory. A sinusoidally varying transverse excitation is applied at the left end of the cantilever beam, while a payload is attached to the free end of the beam. An active control of the transverse vibration based on cubic velocity is studied. Here, cubic velocity feedback law is proposed as a devise to suppress the vibration of the system subjected to primary and subharmonic resonance conditions. Method of multiple scales as one of the perturbation technique is used to reduce the second-order temporal equation into a set of two first-order differential equations that govern the time variation of the amplitude and phase of the response. Then the stability and bifurcation of the system is investigated. Frequency–response curves are obtained numerically for primary and subharmonic resonance conditions for different values of controller gain. The numerical results portrayed that a significant amount of vibration reduction can be obtained actively by using a suitable value of controller gain. The response obtained using method of multiple scales is compared with those obtained by numerically solving the temporal equation of motion and are found to be in good agreement. Numerical simulation for amplitude is also obtained by integrating the equation of motion in the frequency range between 1 and 3. The developed results can be extensively used to suppress the vibration of a transversely excited cantilever beam with tip mass or similar systems actively.     

Non-linear response of a magneto-elastic translating beam with prismatic joint for higher resonance conditions

The non-linear response of a magneto-elastic translating beam having prismatic joint for higher resonance conditions is studied. A periodically varying transverse magnetic field is applied to the system. Two frequencies of prismatic motion and oscillating transverse magnetic field are implemented to the system. The method of multiple scales as one of the perturbation techniques is used to derive two first order ordinary differential equations that govern the time variation of the amplitude and phase of the response. Then a stability analysis is conducted for subharmonic resonance and simultaneous resonance conditions. A parametric study is performed to investigate the effect of magnetic field strength, amplitude of prismatic motion, damping and payload mass on the frequency response curves for both the resonance conditions. The catastrophic failure of the system may occur due to the presence of saddle-node and pitchfork bifurcations. The results obtained by method of multiple scales are compared with those obtained by numerically integrating the reduced equations and are found to be in good agreement. The developed results can be applied to control the vibration of a beam with prismatic joint subjected to magnetic field for third order subharmonic resonance and simultaneous resonance conditions.     

Light and thermal fields in multilayer skin tissue exposed to laser irradiation

A simple model for calculating the light fields created by a laser beam in a multilayer biological tissue is proposed. On the basis of this model, the coefficient of diffuse reflection of skin and the penetration depth of light are found for the wavelength range 400–850 nm and for a wide range of variation in the structural and optical characteristics of the medium. The effect of localized light absorption by blood vessels is taken into account. The results obtained are shown to agree reasonably with published theoretical and experimental data. Using the found depth distributions of the absorbed energy as source functions for the thermal problem, the analytical solution for the spatiotemporal structure of the temperature field in the cutaneous covering irradiated by a laser beam was obtained. The thermal fields determined in terms of single-and two-layer models are compared, and the corresponding differences are discussed. Examples of the temperature depth profiles obtained at different instants after the beginning of irradiation are presented. The results obtained in terms of the analytical method proposed are demonstrated to agree satisfactorily with those yielded by the numerical finite difference scheme of the solution of the system of heat conduction equations.     

Study of the topology of metal-containing granular films by light scattering and atomic force microscopy

The correlation properties of films consisting of granular structures with granules smaller than 6 nm prepared by the laser electrodispersion method are investigated. The correlation functions of the nanoparticle distribution on a transparent substrate are calculated from the angular structure of scattered radiation using the single-scattering approximation, as well as from the data of atomic force microscopy for copper, nickel, and palladium structures with different packing density. The size of coarse particles in nanostructures is estimated.