The accuracy of simulations of the plastic deformation of sheet metal depend to a large extend on the description of the yield surface, the hardening and the friction. In this paper simulations of deep drawing of an AlMg alloy with a shell model are presented. The yield surface is described by a Von Mises, a Hill ’48 and a Vegter yield function. The parameters for the model are based on biaxial...

The Hill coefficient is commonly used to estimate the number of ligand molecules that are required to bind to a receptor to produce a functional effect. However, for a receptor with more than one ligand binding site, the Hill equation does not reflect a physically possible reaction scheme; only under the very specific condition of marked positive cooperativity does the Hill coefficient accurate...

Stribeck’s publications ‘Kugellager für beliebige Belastungen’ and ‘Die wesentlichen Eigenschaften der Gleitund Rollenlager’ were remarkable for their time. Many of the findings were revolutionary and are still considered quite modern. The method used by Stribeck to calculate load distribution between the balls within a ball bearing is still used today, otherwise, a full finite element analysis...

A quad inserted into a turbulent boundary layer of a flat plate and its effect on average heat transfer and the friction coefficient is studied. To optimize this effect, the edge sizes and distance of the quad from the flat plate are continually modified. In each case, simultaneously the heat transfer enhancement and reduction in skin friction are analyzed. For optimization, the genetic algorit...

Ca2+-activated K+ channels from rat muscle transverse tubule membranes were inserted into planar phospholipid bilayers, and the activation of these channels by Ca2+ was studied. On the cytoplasmic side of the channel, calcium ions (in the range 10-100 mumol l-1) increase the opening probability of the channel in a graded way. This 'activation curve' is sigmoid, with an average Hill coefficient ...

The presence of dry friction in mechanical systems induces the existence of an equilibrium set, consisting of infinitely many equilibrium points. The local dynamics of the trajectories near an equilibrium set is investigated for systems with one frictional interface. In this case, the equilibrium set will be an interval of a curve in phase space. It is shown in this paper that local bifurcation...

This paper presents correlations for heat transfer and friction coefficients for combined entry region airflow in 3D rectangular channel as functions of channel depth, Reynolds number, hydraulic diameter, and channel aspect ratio. The correlations were designed to approach known physical limits as the channel aspect ratio and channel depth approach zero, and as the flow becomes fully developed....

The luminance-response function of the brief flash full-field photopic electroretinogram (ERG) rises to a peak before falling to a sub-maximal plateau -- the 'photopic hill'. The combination of on- and off-responses inherent in the brief flash photopic ERG suggests that this luminance-response function could be modelled by the sum of a Gaussian function and a logistic growth function. Photopic ...

We studied gamma-aminobutyric acid (GABA)-mediated currents in short-term cultured dorsal unpaired median (DUM) neurons of cockroach Periplaneta americana using the whole cell patch-clamp technique in symmetrical chloride solutions. All DUM neurons voltage-clamped at -50 mV displayed inward currents (I(GABA)) when 10(-4) M of GABA was applied by pneumatic pressure-ejection pulses. The semi-loga...