Divergence instabilities of nonuniformly prestressed travelling webs

The phenomenon of edge-buckling in an axially moving stretched thin elastic web is described as a nonstandard singularly perturbed bifurcation problem, which is then explored through the application of matched asymptotic techniques. Previous numerical work recently reported in the literature is re-evaluated in this context by approaching it through the lens of asymptotic simplifications. This allows us to identify two distinct regimes characterised by qualitative differences in the corresponding eigen-deformations; some simple approximate formulae for the critical eigenvalues are also proposed. The obtained analytical results capture the intricate relationship between the critical speeds, the background tension, and other relevant physical and geometric parameters that feature in the mathematical model

Wrinkling structures at the rim of an initially stratched circular thin plate subjected to transverse pressure

Short-wavelength wrinkles that appear on an initially stretched thin elastic plate under transverse loading are examined. As the degree of loading is increased so wrinkles appear and their structure at the onset of buckling takes on one of three distinct forms depending on the size of the imposed stretching. With relatively little stretching, the wrinkles sit off the rim of the plate at a location which is not known a priori, but which is determined via a set of consistency conditions. These take the form of constraints on the solutions of certain coupled nonlinear differential equations that are solved numerically. As the degree of stretching grows, so an asymptotic solution of the consistency conditions is possible which heralds the structure that governs a second regime. Now the wrinkle sits next to the rim where its detailed structure can be described by the solution of suitably scaled Airy equations. In each of these first two regimes the Föppl–von Kármán bifurcation equations remain coupled, but as the initial stretching becomes yet stronger the governing equations separate. Further use of singular-perturbation arguments allows us to identify the wavelength wrinkle which is likely to be preferred in practice

A STOCHASTIC MODELING FOR THE UNSTABLE FINANCIAL MARKETS

Considering the present economic context, the measurement of performances has become a permanent preoccupation for organizations, since the whole process is based on it, offering the necessary feedback to identify both the positive actions which have led to favorable results for the organization, and the negative ones, in order to correct them in the future. To do this, we have to measure what is most importantly to measure. Starting from these considerations, the present paper approaches from a theoretical and practical point of view the economic rate of return as the indicator which synthesizes best an organization’s financial-economic performance. We have calculated and analyzed the economic rate of return for a group of Ten Romanian Firms in the food industry, through different calculation relations, pointing out the advantages/disadvantages of each calculation method.belated integral, forward-backward stochastic equations, pathwise uniqueness, financial modeling.

State control can result in good performance for firms

State firms are now hybrid organisations, say Ciprian Stan, David Ahlstrom, Mike W. Peng, Kehan Xu and Garry D. Bruto

Planary Symmetric Static Worlds with Massless Scalar Sources

Motivated by the recent wave of investigations on plane domain wall spacetimes with nontrivial topologies, the present paper deals with (probably) the most simple source field configuration which can generate a spatially planary symmetric static spacetime, namely a minimally coupled massless scalar field that depends only upon a spacelike coordinate, $z$. It is shown that the corresponding exact solutions $({\cal M}, {\bf{\rm g}}_{\pm})$ are algebraically special, type $D - [S - 3T]_{(11)}$, and represent globally pathologic spacetimes with a $G_{4}$ - group of motion acting on ${\bf{\rm R}}^{2} \times {\bf{\rm R}}$ orbits. In spite of the model simplicity, these $\phi$ - generated worlds possess naked timelike singularities (reached within a finite universal time by normal non-spacelike geodesics), are completely free of Cauchy surfaces and contain into the $t$ - leveled sections points which can not be jointed by ${\rm C}^{1}$ - trajectories images of oblique non-spacelike geodesics. Finally, we comment on the possibility of deriving from $({\cal M}, {\bf{\rm g}}_{\pm})$ two other physically interesting ^^ ^^ $\phi$ - generated'' spacetimes, by appropiate jonction conditions in the $(z = 0)$ - plane.Comment: 14 pages, LaTeX format, figures not include