14,623 research outputs found
Modeling the behavior of elastic materials with stochastic microstructure
Even in the simple linear elastic range, the material behavior is not deterministic, but fluctuates randomly around some expectation values. The knowledge about this characteristic is obviously trivial from an experimentalist’s point of view. However, it is not considered in the vast majority of material models in which “only” deterministic behavior is taken into account. One very promising approach to the inclusion of stochastic effects in modeling of materials is provided by the Karhunen-Lo`eve expansion. It has been used, for example, in the stochastic finite element method, where it yields results of the desired kind, but unfortunately at drastically increased numerical costs. This contribution aims to propose a new ansatz that is based on a stochastic series expansion, but at the Gauß point level. Appropriate energy relaxation allows to derive the distribution of a synthesized stress measure, together with explicit formulas for the expectation and variance. The total procedure only needs negligibly more computation effort than a simple elastic calculation. We also present an outlook on how the original approach in [7] can be applied to inelastic material
The Weak and Strong Lefschetz Properties for Artinian K-Algebras
Let A = bigoplus_{i >= 0} A_i be a standard graded Artinian K-algebra, where
char K = 0. Then A has the Weak Lefschetz property if there is an element ell
of degree 1 such that the multiplication times ell : A_i --> A_{i+1} has
maximal rank, for every i, and A has the Strong Lefschetz property if times
ell^d : A_i --> A_{i+d} has maximal rank for every i and d.
The main results obtained in this paper are the following.
1) EVERY height three complete intersection has the Weak Lefschetz property.
(Our method, surprisingly, uses rank two vector bundles on P^2 and the
Grauert-Mulich theorem.)
2) We give a complete characterization (including a concrete construction) of
the Hilbert functions that can occur for K-algebras with the Weak or Strong
Lefschetz property (and the characterization is the same one).
3) We give a sharp bound on the graded Betti numbers (achieved by our
construction) of Artinian K-algebras with the Weak or Strong Lefschetz property
and fixed Hilbert function. This bound is again the same for both properties.
Some Hilbert functions in fact FORCE the algebra to have the maximal Betti
numbers.
4) EVERY Artinian ideal in K[x,y] possesses the Strong Lefschetz property.
This is false in higher codimension.Comment: To appear in J. Algebr
Deterministic Models for Traffic Jams
We study several deterministic one-dimensional traffic models. For integer
positions and velocities we find the typical high and low density phases
separated by a simple transition. If positions and velocities are continuous
variables the model shows self-organized criticality driven by the slowest car.Comment: 11 pages, latex, HLRZ preprint 46/93, UKAM-WP 93.13
An experimental study of adaptive behavior in an oligopolistic market game
We consider an oligopolistic market game, in which the players are competing firm in the same market of a homogeneous consumption good. The consumer side is represented by a fixed demand function. The firms decide how much to produce of a perishable consumption good, and they decide upon a number of information signals to be sent into the population in order to attract customers. Due to the minimal information provided, the players do not have a well--specified model of their environment. Our main objective is to characterize the adaptive behavior of the players in such a situation.Market game, oligopoly, adaptive behavior, learning, Leex
Experiences with a simplified microsimulation for the Dallas/Fort Worth area
We describe a simple framework for micro simulation of city traffic. A medium
sized excerpt of Dallas was used to examine different levels of simulation
fidelity of a cellular automaton method for the traffic flow simulation and a
simple intersection model. We point out problems arising with the granular
structure of the underlying rules of motion.Comment: accepted by Int.J.Mod.Phys.C, 20 pages, 14 figure
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