1.

     A regular parameter perturbation analysis is presented to study the effect of uniform transverse magnetic field in the presence of both viscous dissipation and pressure stress in micropolar fluids on natural convection flows. Four different vertical flows have been analyzed, those adjacent to an isothermal surface and uniform heat flux surface, a plane plume and flow generated from a horizontal line energy source on a vertical adiabatic surface, or wall plume. The pressure term enhances heat transfer from the surface for lower Lykoudis numbers. It is observed that the effect of the Lykoudis numbers on the viscous dissipation is inverse to the pressure stress.

2.

     Over a range of flow rate from 0.6 x 10^-4 to 5 x 10^-4 m³/s, and polymer concentration from 100 to 500 wppm, circumferential temperatures for aqueous solutions of polymer (viscoelastic) flowing over a horizontal cylinder were measured experimentally. The 2.5 cm diameter and 7.5 cm length cylinder was placed in a plexi-glass chamber of inside dimensions 5 cm x 7.5 cm. The cylinder was heated by passing direct electric current through it. The peripherally averaged heat transfer coefficient for viscoelastic polymer solutions decreases, at any fixed flow rate, with increasing polymer concentration.

3.

     The motivation is to optimise mechanical properties, principally to make refractory concretes more resistant to abrasive wear process in such industrial applications as cementry, brick-field, petrochemistry and petroleum refining, industrial incinerators, iron and steel industry and all metals metallurgy. For a better understanding of abrasion resistance it was necessary to develop a new experimental and analytical approach in order to predict its optimum conditions. A new technique based on a fully computerised sclero-topometer has been adapted and applied to this type of heterogeneous composites. A strategy of appropirate experimental measurements has been worked out. The data obtained from experimental techniques on refractory concretes composed of materials as, AL₂O₃, SiC, Chamotte and Bauxite have been interpreted, explored and presented. This paper summarizes the influence of fundamental parameters for abrasive process applied to alumina castables only, for different temperatures of firing.

4.

     A boundary layer analysis is presented for the natural convection flow of a micropolar fluid on a heated vertical plate immersed in a thermally stratified ambient. The governing equations are solved based upon similarity principles. Numerical solutions for the flow velocity, angular velocity and temperature fields are presented for a range of values of material parameters and the Prandtl number of the micropolar fluid.

5.

     A method for studying plane steady flows of an incompressible fluid of variable viscosity is discussed. Basic equations are recast in a new curvilinear coordinate system, by employing some results from differential geometry, and the partial differential equations are derived for the coefficients E, F and G of the first fundamental form of the metric, which are taken as unknown functions. By placing certain conditions on these coefficients, a priori, vortex, radial and parallel flows are determined which have such a property. Some examples are considered to show the applicability of the results to the physically possible situations. It is also indicated that a large number of relations between the temperature T and the viscosity m can be generated due to arbitrariness of streamfunction y.

6.

     Some exact solutions for equations of motion of an incompressible second grade fluid are obtained by employing complex variables and complex functions.

7.

     A generalized equation of motion encountered in many practical vibration problems is treated. The quadratic and cubic nonlinearities are inserted into the equation in the form of arbitrary operators so that general ideas can be drawn about the behavior of such systems. The forced vibrations with linear damping are considered. The primary, subharmonic, superharmonic and combined resonance cases are investigated by directly attacking the partial differential equation using the method of multiple scales (a perturbation technique). The analysis may help to cast this direct method into an algorithmic structure. Finally, the solution procedure is applied to the specific problem of a beam resting on a nonlinear elastic foundation.

8.

     Seven water-blown rigid polyurethane foam with or without biomass materials were prepared and their apparent thermal conductivities were determined by the probe method and ASTM C 518-91 heat flow meter method. The apparent thermal conductivities obtained from the probe method were lower than those obtained from the ASTM method. A theoretical model based on Maxwell's equation (taking into account conduction in the solid and gas phases) and Rosseland's diffusion equation (taking into account radiation across the cell-gas spaces, but excluding convection) was established to predict the apparent thermal conductivity of water-blown rigid polyurethane foam. This model is in agreement with the experimental data obtained from the ASTM C 518-91 method for polyurethane foams without biomass materials, but slightly underpredicts those foams with biomass materials.