Efficiency Of Surface Wave Excitation Research Articles

Uniform large­sized lumber drying system using mw radiation and basing on a single­wire E00 wave energy transmission line

In order to generalize the possibilities of using MW radiation in industrial processes, the given paper considers and analyzes various methods of wood drying. Technological and economic advantages of wood drying in an ultra-high frequency electromagnetic field are well justified. Wood drying in the ultra-high frequency range is considered as the most optimal in contrast to traditional methods. This method is based on the penetration of electromagnetic energy into the material and converting it into heat. The paper reveals the possibility of more effective use of MW radiation. It proposes a method for drying wood and large-sized lumber basing on a single-wire transmission line of electromagnetic energy of the surface wave. The paper also describes the advantages of the proposed method: the use of a single wire covered with a thin layer of dielectric material, the use of a vibratory system for surface wave excitation, and the use of a flat reflector. Special attention is paid to the contact area of the wire with a flat reflector since the perfection of this contact largely determines the efficiency of surface wave excitation. The conducted research estimated the influence of the parameters of the vibratory surface wave excitation system in a single waveguide on the efficiency of its excitation. The proposed vibratory excitation device allows quite a simple step-by-step adjustment of the thermal power in the irradiated object. The design of the dissipation load for surface wave lines has been successfully tested during the laboratory works where certain ways of unclaimed electromagnetic energy utilization were suggested. Following the results of the conducted research, we proposed a physical model of a system for microwave drying of wood and large-sized lumber

Bounded inhomogeneous wave profiles for increased surface wave excitation efficiency at fluid-solid interfaces.

Though the ultrasonic excitation of surface waves in solids is generally realized through the use of a contact transducer, remote excitation would enable standoff testing in applications such as the nondestructive evaluation of structures. With respect to the optimal incident wave profile, bounded inhomogeneous waves, which include an exponentially decaying term, have been shown to improve the surface wave excitation efficiency as compared to Gaussian and square waves. The purpose of this work is to investigate the effect of varying the incident wave spatial decay rate, as applied to both lossless fluid-solid interfaces and to solids with viscoelastic losses included. The Fourier method is used to decompose the incident profile and subsequently compute the reflected wave profile. It is shown that inhomogeneous plane wave theory predicts, to a close approximation, the location of the minimum in the local reflection coefficient with respect to the decay rate for bounded incident waves. Moreover, plane wave theory gives a reasonable indication of the decay rate that maximizes the surface wave excitation efficiency.

Bandgap modes in a coupled waveguide array

This work examines a waveguide array that consists of ten Nb2O5/SiO2 double layers and supports a 0.63-μm surface wave. The deposition of a Nb2O5 capping layer on top of the waveguide array enables a marked increase in the wave field intensity on its surface. The efficiency of surface-wave excitation in the Kretschmann configuration can be optimised by adjusting the number of double layers. We analyse the behaviour of the Bragg mode in relation to the thickness of the layer exposed to air and the transition of this mode from the second allowed band to the first through the bandgap of the system. In addition, the conventional leaky mode converts to a surface mode and then to a guided mode.

Leaky photorefractive surface waves in Bi 12TiO 20 and Bi 12SiO 20 crystals

Consistent experimental and numerical simulation studies of photorefractive surface wave propagation in Bi 12TiO 20 and Bi 12SiO 20 crystals are presented. We induce the photorefractive surface wave with a Gaussian beam of small diameter and show that light leakage from the surface wave takes the form of multiple beam reflection from the crystal surface. The efficiency of surface wave excitation is proved to be much higher for the divergent Gaussian beam than for the convergent one.

Excitation of Love Waves in a Thin Film Layer by a Line Source

The excitation of a Love surface wave guided by a thin film layer deposited on a semiinfinite substrate is studied in this paper. Both the thin film and the substrate are considered to be elastically isotropic. Amplitudes of the surface wave in the thin film region and the substrate are found in terms of the strength of a line source vibrating in a direction transverse to the propagating wave. In addition to the surface wave, the bulk shear wave excited by the source is also studied. Analytical expressions for the bulk wave amplitude as a function of the direction of propagation, the acoustic powers transported by the surface and bulk waves, and the efficiency of surface wave excitation are obtained. A numerical example is given to show how the bulk wave radiation pattern depends upon the source frequency, the film thickness and other important parameters of the problem. The efficiency of surface wave excitation is also calculated for various parameter values.

Excitation of a grounded dielectric slab by a horizontal dipole

The structure consisting of a horizontal electric dipole above a grounded dielectric slab is examined, primarily from the standpoint of power distribution among the two power-carrying wave components, i.e., surface and space waves. It is shown that surface wave propagation is always in the form of two distinct modes characterized by the same cutoff properties. Also, surface wave excitation efficiency curves are given for a range of parameter variation.