Computational steering of a multi-objective genetic algorithm using a PDA

The execution process of a genetic algorithm typically involves some trial-and-error. This is due to the difficulty in setting the initial parameters of the algorithm – especially when little is known about the problem domain. The problem is magnified when applied to multi-objective optimisation, as care is needed to ensure that the final population of candidate solutions is representative of the trade-off surface. We propose a computational steering system that allows the engineer to interact with the optimisation routine during execution. This interaction can be as simple as monitoring the values of some parameters during the execution process, or could involve altering those parameters to influence the quality of the solutions produce by the optimisation process

Passage of a Bessel beam through a classically forbidden region

The motion of an electromagnetic wave, through a classically-forbidden region, has recently attracted renewed interest because of its implication with regard to the theoretical and experimental problems of superluminality. From an experimental point of view, many papers provide an evidence of superluminality in different physical systems. Theoretically, the problem of a passage through a forbidden gap has been treated by considering plane waves at oblique incidence into a plane parallel layer of a medium with a refractive index smaller than the index of the surrounding medium, and also confined (Gaussian) beams, still at oblique incidence. In the present paper the case of a Bessel beam is examined, at normal incidence into the layer (Secs. II and III), in the scalar approximation (Sec. IV) and by developing also a vectorial treatment (Sec. V). Conclusions are reported in Sic. VI

Quasi-static stationary-periodic model of percussive deep drilling

Copyright @ 2005 Patron EditoreIn the percussively deep drilling, the rock is modeled by an infinite elastic medium with a semi-infinite cylindrical bore-hole having a curvilinear bottom. First, the stationary indentation is formulated as a non-classical non-linear free-boundary contact problem with unknown rupturing and non-rupturing parts of the bore-hole boundary. Then the stationary-periodic per- cussive drilling problem is reduced to the stationary one on the rupture progression stage of the cycle and to the classical contact problem on the reverse and progression-before-rupture stages of the cycle. This provides a nonlinear progression - force diagram for the bit dynamics prediction.This work is supported by the research grant GR/R85556/01 "Nonlinear Dynamics and Rock Contact Fracture Mechanics in Modelling of Vibration Enhanced Drilling" of the Engineering and Physical Sciences Research Council, UK

Automated Generation of Geometric Theorems from Images of Diagrams

We propose an approach to generate geometric theorems from electronic images of diagrams automatically. The approach makes use of techniques of Hough transform to recognize geometric objects and their labels and of numeric verification to mine basic geometric relations. Candidate propositions are generated from the retrieved information by using six strategies and geometric theorems are obtained from the candidates via algebraic computation. Experiments with a preliminary implementation illustrate the effectiveness and efficiency of the proposed approach for generating nontrivial theorems from images of diagrams. This work demonstrates the feasibility of automated discovery of profound geometric knowledge from simple image data and has potential applications in geometric knowledge management and education.Comment: 31 pages. Submitted to Annals of Mathematics and Artificial Intelligence (special issue on Geometric Reasoning

Application of damage mechanics in percussive drilling modelling

A stationary-periodic quasi-static model of rock percussive deep drilling is introduced. First, an auxiliary problem of stationary indentation of a rigid indentor is considered. The rock is modelled by an in¯nite elastic medium with damage-induced material softening. The stationarity of the problem allows to reduce the damage history in a material point to the damage distribution down in space. The bore-hole is a semi-in¯nite cylinder with a curvilinear bottom. It is assumed the indentation is produced by a stationary motion of the rupture front at which an appropriate rock strength condition is violated. The bore-hole boundary is not known in advance and consists of four parts: a free of traction non-rupturing part, a contact non-rupturing part, a free of traction part of the rupture front, and a contact part of the rupture front. Thus the problem is formulated as a non-local non-linear free-boundary contact problem and algorithms of its numerical solution are discussed. The problem solution provides axial force necessary for the drill bit progression through the rock. Then the stationary-periodic percussive drilling problem is reduced to the stationary problem on the rupture progression stage of the cycle and to the classical contact problem on the reverse and progression-before-rupture stages of the cycle. As a result, this provides a nonlinear progression-force diagram

Fast and easy blind deblurring using an inverse filter and PROBE

PROBE (Progressive Removal of Blur Residual) is a recursive framework for blind deblurring. Using the elementary modified inverse filter at its core, PROBE's experimental performance meets or exceeds the state of the art, both visually and quantitatively. Remarkably, PROBE lends itself to analysis that reveals its convergence properties. PROBE is motivated by recent ideas on progressive blind deblurring, but breaks away from previous research by its simplicity, speed, performance and potential for analysis. PROBE is neither a functional minimization approach, nor an open-loop sequential method (blur kernel estimation followed by non-blind deblurring). PROBE is a feedback scheme, deriving its unique strength from the closed-loop architecture rather than from the accuracy of its algorithmic components