Dynamics and morphology of hole growth in a film of power hardening viscoplastic solid [ yield stress approximately (strain-rate)(n)] is investigated. At short times the growth is exponential and depends on the initial hole size. At long times, for n>1 / 3, the growth is again exponential but with a different exponent. However, for n<1 / 3 the hole growth slows and the hole radius approaches an...

Miniaturization of electronics to the nanoscale brings new challenges. Because of their small size and immense information and power processing capacity, large temperature gradients exist across nanoelectronics and power electronics solder joints. In this paper, a fully coupled thermomechanical-diffusion model is introduced to study the thermomigration induced strength degradation. A nonlinear ...

as the turbine industries need to manufacture turbine blades made of martensitic stainless steel aisi 420 with high toughness and wear resistance, local laser hardening has become more and more important. in this research, surface of the samples was initially hardened by high-power pulsed laser beam; then, optimum parameters of hardening were calculated and wear resistance of surface hardened s...

The process of laser beam transformation hardening is principally controlled by two independent parameters, the absorbed laser power on a given area and the interaction time. These parameters can be transformed into two functional parameters: the maximum surface temperature and the hardening depth. It has been proved that with a constant hardening depth the results (hardness. residual stress. e...

A system of four coupled rate equations for the development of the densities of mobile and redundant dislocations and of mobile and immobile disclinations with time or strain is proposed to describe the microstructure evolution up to large strains. The densities of redundant dislocations and of immobile disclinations are connected to ow stress contributions with the help of Mughrabi's composite...

in the present study, the production of dextran from date extract and sucrose as carbon sources by the bacterium leuconostoc mesenteroides nrrl b512 (f) was investigated. in comparison to blue dextran (mw≈2000 da), dextran molecular weight was reduced (mw2000 kda). flow behavior indices of dextran solutions from date extracts were investigated and rheological parameters were evaluated at concen...

Indentation hardness has been used extensively for material characterization and many recent computational studies have established quantitative relationships between elasto-plastic mechanical properties and the response in instrumented indentation. In contrast, very few studies have systematically quantified the effect of the plastic deformation characteristics on the frictional sliding respon...

We present the results of the analysis of the broad-band spectrum of Cygnus X-1 from 3.0 to 200keV, using data from a 10ksec observation by the Rossi X-ray Timing Explorer. The spectrum can be well described phenomenologically by an exponentially cut-off power law with a photon index Γ = 1.45 −0.02 (a value considerably harder than typically found), e-folding energy Ef = 162 +9 −8 keV, plus a d...

There are many assumptions that have been considered when describing black liquor droplet combustion. These include assuming an isothermal particle, a constant diameter particle, inert inorganic species, and one-film diffusion model. This paper shows the effects of systematically relaxing these factors for a 1-D spherical model for black liquor combustion. The flame is described using boundary ...