1.

     The effect of chemical reaction on unsteady forced and free-convection flow past an infinite vertical plate has been analysed. Analytical expressions for the velocity field, leading edge effects, and skin-friction have been obtained by using the Laplace transform technique. The effects of K (chemical reaction parameter), Sc (Schmidt number) and t (time parameter) on the velocity field, leading edge, and skin-friction have been extensively discussed.

2.

     A nonsimilar boundary layer analysis is presented for the problem of combined convection from a vertical wedge in a porous medium saturated with a power-law type non-Newtonian fluid. The transformed conservation laws are solved numerically for the case of variable surface heat flux conditions. Results for the details of the velocity and temperature fields as well as the Nusselt number have been presented. The viscosity index ranged from 0.5 to 1.5 and the wedge angle parameter ranged from 0 to 1.

3.

     Based on a mutiple-entanglement model, a new relation of linear viscoelastic functions (the zero rate shear viscosity 'eta'₀, the zero extensional rate viscosity 'eta'_ext⁰, the first normal stress coefficient 'psi'₁₀⁰ , and the terminal relaxation time 'tau') to the molecular weight and its distribution for flexible chain polymer were formulated. The dependence of scaling of exponent of entanglement networks in the long entanglement spacing |'ypsilon' or ||'ypsilon' for testing flexible chain polymers on the primary molecular weight and the number of testing polymers was derived from the two types relaxation mechanisms. A new method for determining the |'ypsilon' and ||'ypsilon' for mono and polydipersed polymer was proposed. It shows that when M_n = 3M_e to 6M_e, the values of |'ypsilon' can range from 3.77 down to 3.33, their values are in a good agreement with the experimental results for different molecular weight of mono-and polydispersed polymers and different polymer species. The dependence of 'eta'₀, 'psi'₁₀⁰, 'eta'_ext⁰ and 'tau'_T on the weight average molecular weight and its distribution was derived from the constrained multidimensional number of entanglements per polymer chain and the primary molecular weight distribution function with the statistical method.

4.

     An experimental investigation has been conducted on the influence of helical-coiled wires in turbulent pipe flows in the Reynolds number range of 30000 =< Re =< 90000. Helical coiled wires of varying diameter d, length L, pitch p, number of coils n and helix angle a were used in the study. The dimensionless insert parameters covered the ranges 13.33 =< D/d =< 26.66, 5 =< p/d =< 21.3, 50 =< L/d =< 300, 4.7 =< n =< 30 with helix angles 66.6^o =< 'alpha' =< 79^o. The influence of inserts was determined through the measurements of mean axial, tangential velocity profiles and static pressure profiles in the flow field. Hydrodynamic performance of inserts were expressed in terms of correlations between flow friction factor, f and non-dimensional insert parameters.

5.

     The fully developed two-phase turbulent isothermal Fanning friction factors for air-powerlaw fluid flows through a horizontal tube were measured experimentally. The test fluids were aqueous solutions of Carbopol. Over the range of the generalized Reynolds number (Re') from 10.000 to 100.000, the homogeneous model was found to be accurate enough for engineering prediction of turbulent friction factor for air and power-law fluid flows through horizontal tubes.

6.

     The subatomistic treatment of the theory of radiation allows the intrinsic oscillation of the electron to be interpreted as the crucial mechanism underlying the emission and absorption of heat. Considering the three-dimensional Maxwell-Boltzmann energy-distribution, the ordinary method of statistics yields the mean energy per particle in the form ____ that is compatible with the Planck radiation law. The theory defines the conditions for space quantization of the orbital and intrinsic angular momenta of elementary particles, transposing the probabilistic views of classical thermodynamics into quantum mechanics of a single atom.

7.

     A theoretical analysis is presented investigating the stability of a symmetrical, rigid rotor on a flexibly supported journal bearing. Oil-film flow in the bearing is assumed to be turbulent and the dynamics of the system is studied by calculating the components of fluid film force by solving the generalized Reynolds equation modified to include the effect of turbulence and using these in the non-linear equation of motion of the journal and the bearing. The modified Reynolds equation is solved for pressure distribution by using finite difference method with S.O.R. scheme. The equations of motion are solved by state space technique using the fourth order Runge-Kutta method as the tool for solving the non-linear equations. This gives the transient response of the journal-bearing system. The locus of the journal centre indicates whether the system is stable, marginally stable or unstable. The results indicate that other parameters e.g. aspect ratio, eccentricity ratio, mass parameter, stiffness and damping parameters of the support system remaining fixed an increase in turbulence results towards more stable orbit.

8.

     In the paper, equations of the motion of media completed by constitutive relations rendering properties of materials have been presented. The physical-mathematical model described in this paper contains a description of elastic/visco-plastic properties of materials, considers their strength characteristics and possibility of crack formation. Equations of the problem as a result of their complexity, non-linearity, multidimensionality are solved numerically. In this case, the method of free particles has been applied in numerical analysis. The results of exemplary 2D and 3D numerical solutions illustrating processes of explosive formation of projectiles have been presented. High degree of accuracy of the results of the computer simulations makes the applied theoretical methods an important tool for the design of explosive formation of projectiles (EFP).

9. Brief note

     The concept of improving the tooth cavity's fill in forging of bevel gears is based on the relationship between the initial height and impression's depth of the preform. Through their optimal relation the bulge of the preform can be limited and thereby the metal displacement to the die corners intensified. Through an analytical determination of the bulging free surface at constant friction and then its minimizing, it is shown that an optimal relation of the preform's dimensions can be predicted. This concept is experimentally proved and can be applied instead of using more complicated computing methods.