In this paper, Propagation of an electromagnetic beam wrapped around the axis of a thin axisymmetric Wave guide embedded in a square law medium, depending on a b2 parameter small enough to make the b2n terms negligible for n  ³ 2 has been analyzed. To solve Maxwell's equations in this Wave guide, a paraxial approximation of the Wave equations, satisfied by the electric and magnetic components of the electromagnetic field, has been used. The solutions of the corresponding paraxial Wave equations describe beam Propagation by a series expansion of Gaussian modes.

The flow field which results from an expansion Wave entering a cavity from an upstream tube, and the focusing effect which occurs, is investigated. Different cavity geometries, different expansion Wave pressure ratios and different expansion Wave widths are explored. As the expansion Wave propagates into the cavity it induces flow in the opposite direction and back down the walls. The flow experiences compression as it flows out back into the tube because of the concave surface of the cavity it encounters. This can result in the formation of shock Waves which can propagate back up into the cavity. Very low pressure and temperature regions can develop because of the focusing action of the expansion. A convenient way of generating an expansion Wave numerically and/or experimentally is in a shock tube. This consists of a tube divided into two compartments, one at high pressure and one at low pressure separated by a frangible diaphragm. On bursting the diaphragm, a shock Wave travels in one direction and an expansion in the other towards the cavity. Whilst ideal boundary conditions can be imposed in numerical simulation laboratory experiments are complicated by the diaphragm being curved and having a finite opening time. The effect of an initially curved diaphragm is briefly considered. The expansion Wave pressure ratio was altered by changing the initial pressure ratio across the diaphragm. For an initially high pressure ratio, supersonic flow can occur behind the trailing edge of the expansion Wave which has a marked influence on the flow. The width of the Wave is dependent on the distance of the diaphragm from the cavity and also has a significant influence on the flow. As the width of the Wave increases and the density gradient decreases, focusing effects becomes significantly weaker. Correspondence between experiment and simulation is examined.

In this article, the dispersion of Propagation Waves in an arbitrary direction in laminated composite plates is studied in the framework of elasticity. Three-dimensional field equations of elasticity are considered, and the characteristic equation is obtained on employing the continuity of displacements and stresses at the layers' interfaces. Obtained characteristic equation is further simplified by making use of the properties of the block matrices. Some important particular cases such as of free Waves on reducing plates to single layer and the surface Waves when thickness tends to infinity are also discussed. Numerical results are also obtained and represented graphically.

The present investigation is concerned with the reflection of plane Waves from a free surface of a micropolar thermoelastic diffusion half space in the context of coupled theory of thermoelastic diffusion. The amplitude ratios of various reflected Waves are obtained in a closed form. The dependence of these amplitude ratios with an angle of Propagation as well as other material parameter are shown graphically. Effects of micropolarity and diffusion are observed on these amplitude ratios. Some special cases of interest are also deduced from the present investigation.

An approximation technique is considered for computing transmission and reflection coefficients for Propagation of an elastic pulse through a planar slab of finite width. The Propagation of elastic pulse through a planar slab is derived from first principles using straightforward time-dependent method. The paper ends with calculations of enhancement factor for the elastic plane Wave and it is shown that it depends on the velocity ratio of the Wave in two different media but not the incident Wave form. The result, valid for quite arbitrary incident pulses and quite arbitrary slab inhomogeneities, agrees with that obtained by time-independent methods, but uses more elementary methods.

An approximation technique is considered for computing transmission and reflection coefficients for plane Waves propagating through stratified slabs. The Propagation of elastic pulse through a planar slab is derived from first principles using straightforward time-dependent method. The paper ends with calculations of enhancement factor for the elastic plane Wave and it is shown that it depends on the velocity ratio of the Wave in two different media but not the incident Wave form. The result, valid for quite arbitrary incident pulses and quite arbitrary slab in homogeneities, agrees with that obtained by time-independent methods, but uses more elementary methods.