Performance study on newly developed AC magnetic suspension system using magnetic resonance coupling

A newly developed AC magnetic suspension system is designed and fabricated to investigate the performances. A new concept of design is revealed for operating the apparatus differentially where the floator is kept at a constant position despite changing the parameters of the upper stator electromagnets. An extensive finite element analysis is conducted to estimate the basic characteristics of the system. A permanent magnet is incorporated in this system to reduce the required supply energy to the stator electromagnets. Magnetic suspension with a maximum gap of 2.0 mm without any control with the upper electromagnet in cumulative coupling mode and with a gap of 3.0 mm with indirect damping in the differentially operated mode is achieved. The indirect damping is achieved by applying PD control to the stator. The individual force, current and phase for variable frequency and gap between primary and secondary electromagnet are measured to examine the basic characteristics and performances.

Theoretical model of infrared spectra of hydrogen bonds in molecular crystals of 2-thiopheneacetic acid: Fermi resonance and Davdov coupling effects.

<p>A quantum theoretical approach, within the adiabatic approximation and taking into account a strong non-adiabatic correction via the resonant exchange between the fast mode excited states of the two moieties of the dimer. The intrinsic anharmonicity of the low-frequency mode through a Morse potential, direct and indirect damping, and a selection rule breaking mechanism for forbidden transitions, is applied to reproduce the υ_X-HIR line shape of cyclic dimers of moderately H-bonded species in the crystalline phase. The results are used to gain an insight into the experimental spectral line shapes obtained by the transmission method. This approach fits satisfactorily the experimental line shape of 2-thiopheneacetic acid and predicts their evolution with isotopic substitution. Numerical calculations show that mixing of all these effects allows one to reproduce the main features of the experimental IR line shapes. </p>

Blow-Up of Solutions for a System of Petrovsky Equations with an Indirect Linear Damping

In this paper, we consider a coupled system of Petrovsky equations in a bounded domain with clamped boundary conditions. Due to several physical considerations, a linear damping which is distributed everywhere in the domain under consideration appears only in the first equation whereas no damping term is applied to the second one (this is indirect damping). Many studies show that the solution of this kind of system has a polynomial rate of decay as time tends to infinity, but does not have exponential decay. For four different ranges of initial energy, we show here the blow-up of solutions and give the lifespan estimates by improving the method of Wu (Electron. J. Diff. Equ. 105, 1 (2009)) and Li et al. (Nonlin. Anal. 74, 1523 (2011)). From the applications point of view, our results may provide some qualitative analysis and intuition for the researchers in other fields such as engineering and mechanics when they study the concrete models of Petrovsky type.