Search results for "Mathematica"
showing 10 items of 7971 documents
A Modified Tabu Thresholding Approach for the Generalised Restricted Vertex Colouring Problem
1996
We present a modification of the Tabu Thresholding (TT) approach and apply it to the solution of the generalised restricted vertex colouring problem. Both the bounded and unbounded cases are treated. In our algorithms, the basic TT elements are supplemented with an evaluation function that depends on the best solution obtained so far, together with a mechanism which reinforces the aggressive search in the improving phase, and new diversification strategies which depend on the state of the search. The procedure is illustrated through the solution of the problem of minimising the number of workers in a heterogeneous workforce.
A graph colouring model for assigning a heterogeneous workforce to a given schedule
1996
Abstract We analyze a heterogeneous workforce assignment problem in which the minimum number of workers required to carry out a machine load plan is calculated. The problem is formulated as a restricted vertex colouring problem and a branch and bound algorithm is presented. The special characteristics of the graph to be coloured allow an efficient implementation of the branch and bound. Computational results show that the algorithm can solve problems of 50 activities, 5, 10 and 15 machines and between 2 to 15 different types of workers in just a few seconds.
Non-Abelian Ball-Chiu vertex for arbitrary Euclidean momenta
2017
We determine the non-Abelian version of the four longitudinal form factors of the quark-gluon vertex, using exact expressions derived from the Slavnov-Taylor identity that this vertex satisfies. In addition to the quark and ghost propagators, a key ingredient of the present approach is the quark-ghost scattering kernel, which is computed within the one-loop dressed approximation. The vertex form factors obtained from this procedure are evaluated for arbitrary Euclidean momenta, and display features not captured by the well-known Ball-Chiu vertex, deduced from the Abelian (ghost-free) Ward identity. The potential phenomenological impact of these results is evaluated through the study of spec…
A gauge-technique Ansatz for the three gluon vertex of the background field method
2011
The vertex connecting one background gluon with two quantum ones constitutes a central ingredient in the gauge-invariant Schwinger-Dyson equation that determines the non-perturbative dynamics of the gluon propagator. This vertex satisfies a Ward identity with respect to the background gluon, and a Slavnov-Taylor identity with respect to the two quantum gluons. We present a complete Ansatz for this vertex, which satisfies both aforementioned identities. This entire construction depends crucially on a set of constraints relating the various form-factors of the ghost Green's functions appearing in the Slavnov-Taylor identity satisfied by the vertex. The validity of these constraints is demonst…
QSPR Modeling of Hydrocarbon Dipole Moments by Means of Correlation Weighting of Local Graph Invariants
2003
Hydrocarbon dipole moments are calculated by means of correlation weighting of local graph invariants within the context of QSPR theory. This sort of flexible topological descriptor is used for several parameters: local invariants of k th vertex in the labeled hydrogen filled graph extended connectivity of zero-, first- and second-orders, number of paths of length 2 at k th vertex and valence shell of the k th vertex. The models predict hydrocarbon dipole moments in a quite sensible way. The best model is that one based upon numbers of path length 2 correlation weighting.
An equivalent single-layer model for magnetoelectroelastic multilayered plate dynamics
2012
Abstract An equivalent single-layer model for the dynamic analysis of magnetoelectroelastic laminated plates is presented. The electric and magnetic fields are assumed to be quasi-static and the first-order shear deformation theory is used. The formulation of the model provides for a preliminary fulfillment of the electro-magnetic governing equations, which allows to determine the electric and magnetic potential as functions of the mechanical variables. Then, by using this result, the equations of motion are written leading to the problem governing equations. They involve the same terms of the elastic dynamic problem weighted by effective stiffness coefficients, which take the magneto-elect…
On Bifurcation Analysis of Implicitly Given Functionals in the Theory of Elastic Stability
2015
In this paper, we analyze the stability and bifurcation of elastic systems using a general scheme developed for problems with implicitly given functionals. An asymptotic property for the behaviour of the natural frequency curves in the small vicinity of each bifurcation point is obtained for the considered class of systems. Two examples are given. First is the stability analysis of an axially moving elastic panel, with no external applied tension, performing transverse vibrations. The second is the free vibration problem of a stationary compressed panel. The approach is applicable to a class of problems in mechanics, for example in elasticity, aeroelasticity and axially moving materials (su…
Neural network-based models for a vibration suppression system equipped with MR brake
2012
This paper is devoted to the modeling and simulation of a full-scale commercially available magnetorheological (MR) brake installed in a semi-active suspension (SAS) system. The analysis of the Bouc-Wen and Dahl mathematical models of MR damper is presented. Influence of their parameters on the response is explored. Subsequently, by using the neural networks, the parameters characterizing each model are estimated. This makes it possible to perform the comparative analysis of the suggested damper models responses with the measured experimental results. The novelty of the presented methodology is the application of artificial intelligence methods to estimate model parameters of a MR brake uti…
On the 2485 keV γ-ray line in208Pb
1995
The 2485 keV γ-ray line, which in a GSI experiment originally was suggested to decay from the 6+ state of the double octupole vibration in 208Pb, was in a later experiment in Berlin proposed to belong to 207Pb, populated in one-neutron transfer. It has been searched for in the present experiment using Coulomb excitation.
Augstākā algebra: lekcijas, lasītas Latvijas Universitātes matemātikas un dabaszinātņu fakultātē
1936
Lekcijas sakārtojis Fogels, Ernests ; rediģējis Lūsis, Arvīds.