Branch and bound based coordinate search filter algorithm for nonsmooth nonconvex mixed-integer nonlinear programming problems

Publicado em "Computational science and its applications – ICCSA 2014...", ISBN 978-3-319-09128-0. Series "Lecture notes in computer science", ISSN 0302-9743, vol. 8580.A mixed-integer nonlinear programming problem (MINLP) is a problem with continuous and integer variables and at least, one nonlinear function. This kind of problem appears in a wide range of real applications and is very difficult to solve. The difficulties are due to the nonlinearities of the functions in the problem and the integrality restrictions on some variables. When they are nonconvex then they are the most difficult to solve above all. We present a methodology to solve nonsmooth nonconvex MINLP problems based on a branch and bound paradigm and a stochastic strategy. To solve the relaxed subproblems at each node of the branch and bound tree search, an algorithm based on a multistart strategy with a coordinate search filter methodology is implemented. The produced numerical results show the robustness of the proposed methodology.This work has been supported by FCT (Fundação para a Ciência e aTecnologia) in the scope of the projects: PEst-OE/MAT/UI0013/2014 and PEst-OE/EEI/UI0319/2014

Detection of bilateral symmetry using spatial filters

When bilaterally symmetric images are spatially filtered and thresholded, a subset of the resultant 'blobs' cluster around the axis of symmetry. Consequently, a quantitative measure of blob alignment can be used to code the degree of symmetry and to locate the axis of symmetry. Four alternative models were tested to examine which components of this scheme might be involved in human detection of symmetry. Two used a blob-alignment measure, operating on the output of either isotropic or oriented filters. The other two used similar filtering schemes, but measured symmetry by calculating the correlation of one half of the pattern with a reflection of the other. Simulations compared the effect of spatial jitter, proportion of matched to unmatched dots and width or location of embedded symmetrical regions, on models' detection of symmetry. Only the performance of the oriented filter + blob-alignment model was consistent with human performance in all conditions. It is concluded that the degree of feature co-alignment in the output of oriented filters is the cue used by human vision to perform these tasks. The broader computational role that feature alignment detection could play in early vision is discussed, particularly for object detection and image segmentation. In this framework, symmetry is a consequence of a more general-purpose grouping scheme

Novel multi-pass E-M system for locating buried optical cables using Faraday rotation of the transmitted light

We present a novel high-sensitivity location technology for buried dielectric optical cables. A downwardtraveling RF EM wave modulates the state of polarization of the light guided by the buried fibre cable. The cable is located by observing the peak Faraday polarization modulation as the field generator is traversed laterally above the buried cable. We show we can enhance the sensor sensitivity firstly by employing a dual-pass method, giving 6dB SNR improvement, and then a more sophisticated multiple pass system, capable of achieving further SNR improvements. We show our systems demonstrate SNR improvements close to the theoretical limit

A novel method for location of buried optical cables where an incident EM-wave modulates the polarization of guided light using the Faraday effect

This paper presents results and detailed theoretical analysis of a novel method to locate the position of buried optical cables. A travelling EM wave (RF), generated from above ground, modulates the state of polarization of the light propagating in the single-mode fibre to be located. The magnitude and phase of this modulation are detected at the end of the fibre route and the results are relayed to the operator of the locator. By observing the amplitude of this modulation, the lateral position of the buried service can be determined. We have demonstrated an 18 dB signal-to-noise ratio, at a buried depth of 1.5 m, in wet clay soil, using a radiated RF power of 38 W at 144 MHz

Location of buried optical service cables using a remote EM-wave to modulate the polarisation state of guided light via the Faraday effect

This paper presents the first results and theoretical examination of a method to locate the position of buried optical cables. A traveling EM-wave (RF), generated from above ground, modulates the state of polarization of the light guided by the fiber to be located. The magnitude and phase of this modulation are detected at the end of the fiber route and the results relayed to the operator. By observing the amplitude of this modulation the lateral position of the buried service can be determined. We have demonstrated 18dB signal/noise ratio, at a buried depth of 1.5m, in wet clay soil, using a radiated RF power of 38W at 144MHz