On the combination of kernels for support vector classifiers

The problem of combining different sources of information arises in several situations, for instance, the classification of data with asymmetric similarity matrices or the construction of an optimal classifier from a collection of kernels. Often, each source of information can be expressed as a kernel (similarity) matrix and, therefore, a collection of kernels is available. In this paper we propose a new class of methods in order to produce, for classification purposes, an unique and optimal kernel. Then, the constructed kernel is used to train a Support Vector Machine (SVM). The key ideas within the kernel construction are two: the quantification, relative to the classification labels, of the difference of information among the kernels; and the extension of the concept of linear combination of kernels to the concept of functional (matrix) combination of kernels. The proposed methods have been successfully evaluated and compared with other powerful classifiers and kernel combination techniques on a variety of artificial and real classification problems

ON THE COMBINATION OF KERNELS FOR SUPPORT VECTOR CLASSIFIERS

The problem of combining different sources of information arises in several situations, for instance, the classification of data with asymmetric similarity matrices or the construction of an optimal classifier from a collection of kernels. Often, each source of information can be expressed as a kernel (similarity) matrix and, therefore, a collection of kernels is available. In this paper we propose a new class of methods in order to produce, for classification purposes, an unique and optimal kernel. Then, the constructed kernel is used to train a Support Vector Machine (SVM). The key ideas within the kernel construction are two: the quantification, relative to the classification labels, of the difference of information among the kernels; and the extension of the concept of linear combination of kernels to the concept of functional (matrix) combination of kernels. The proposed methods have been successfully evaluated and compared with other powerful classifiers and kernel combination techniques on a variety of artificial and real classification problems.

Evaluating a human-robot interface for exploration missions

The research reported in this paper concerns the design, implementation, and experimental evaluation of a Human-Robot Interface for stationary remote operators, implemented for a PC computer. The GUI design and functionality is described. An Autonomy Management Model has been implemented and explained. We have conducted user evaluation, making two set of experiments, that will be described and the resulting data analyzed. The conclusions give an insight on the most important usability concerns, regarding the operator situational awareness. The scalability of the interface is also experimentally studied

Use of portable devices and confocal Raman spectrometers at different wavelength to obtain the spectral information of the main organic components in tomatoes (Solanum Lycopersicum) fruits

Tomato (Solanum lycopersicum) fruit samples, in two ripening stages, ripe (red) and unripe (green), collected from a cultivar in the North of Spain (Barrika, Basque Country), were analyzed directly, without any sample pretreatment, with two different Raman instruments (portable spectrometer coupled to a micro-videocamera and a confocal Raman microscope), using two different laser excitation wavelengths (514 and 785 nm, only for the confocal microscope). The combined use of these laser excitation wavelengths allows obtaining, in a short period of time, the maximum spectral information about the main organic compounds present in this fruit. The major identified components of unripe tomatoes were cutin and cuticular waxes. On the other hand, the main components on ripe tomatoes were carotenes, polyphenoles and polysaccharides. Among the carotenes, it was possible to distinguish the presence of lycopene from b-carotene with the help of both excitation wavelengths, but specially using the 514 nm one, which revealed specific overtones and combination tones of this type of carotene.This work has been financially supported by Research Project S-PE11-UN128 of the Basque Country government. Technical and support provided by SGIker (UPV/EHU, MICINN, GV/EJ, ESF) is gratefully acknowledged

Computation of the optimal relative pose between overlapping grid maps through discrepancy minimization

Grid maps are a common environment representation in mobile robotics. Many Simultaneous Localization and Mapping (SLAM) solutions divide the global map into submaps, forming some kind of graph or tree to represent the structure of the environment, while the metric details are captured in the submaps. This work presents a novel algorithm that is able to compute a physically feasible relative pose between two overlapping grid maps. Our algorithm can be used for correspondence search (data association), but also for integrating negative information in a unified way. This paper proposes a discrepancy measure between two overlapping grid maps and its application in a quasi Newton optimization algorithm, with the hypothesis that minimizing such discrepancy could provide useful information for SLAM. Experimental evidence is provided showing the high potential of the algorithm

INFLUENCE OF WHEELED TYPES OF A Skidder ON PRODUCTIVITY AND COST OF THE FOREST HARVESTING

AbstractThe objective of this study was to evaluate the influence of different wheel types of a skidder on productivity and cost of Pinus taeda L. wood extraction. The study was conducted in a forestry company located in the municipality of Mandirituba, Paraná state, Brazil. The technical and cost analyses included a time and motion study of the wood extraction activity. The productivity, operative efficiency, energy consumption and the production and operational costs were determined for the machines with different wheel types: SDP - skidder with rubber tires; SD2 – skidder with tracks on the two front tires; and SD4 – skidder with tracks on the four tires. Results showed that the activity that demanded most time in the operational cycle was the maneuvering of the machines to pick up more than one tree, resulting in lost of productivity and need of improvement in the operational planning. The skidder equipped only with rubber tires showed higher productivity and lower production cost in the longest extraction distances, caused by the higher operating speed of the machine.Keywords: Timber extraction; wheel types; operating efficiency. ResumoInfluência dos rodados de um skidder na produtividade e no custo da extração florestal. Este trabalho objetivou avaliar a influência de diferentes tipos de rodados de um skidder na produtividade e no custo da extração de madeira de Pinus taeda L. O estudo foi conduzido em uma empresa florestal localizada no município de Mandirituba, estado do Paraná, Brasil. As análises técnica e de custo englobaram um estudo de tempos e movimentos da operação de extração florestal. Foi determinado a produtividade, eficiência operacional, rendimento energético e custos operacionais e de produção das máquinas equipadas com diferentes tipos de rodados: SDP – skidder com rodados de pneus; SD2 – skidder com pneus dianteiros recobertos com semiesteiras e SD4 – skidder com os quatro pneus recobertos com semiesteiras. Os resultados mostraram que a atividade que demandou o maior tempo do ciclo operacional foram as manobras realizadas pelas máquinas para apanhar mais de uma árvore, ocasionando perda de produtividade e necessidade de melhoria no planejamento operacional. O skidder equipado somente com rodados de pneus apresentou maior produtividade e menor custo de produção nas maiores distâncias de extração, ocasionado pela maior velocidade operacional da máquina.Palavras-chave: Extração florestal; tipos de rodados; eficiência operacional.AbstractThe objective of this study was to evaluate the influence of different wheel types of a skidder on productivity and cost of Pinus taeda L. wood extraction. The study was conducted in a forestry company located in the municipality of Mandirituba, Paraná state, Brazil. The technical and cost analyses included a time and motion study of the wood extraction activity. The productivity, operative efficiency, energy consumption and the production and operational costs were determined for the machines with different wheel types: SDP - skidder with rubber tires; SD2 – skidder with tracks on the two front tires; and SD4 – skidder with tracks on the four tires. Results showed that the activity that demanded most time in the operational cycle was the maneuvering of the machines to pick up more than one tree, resulting in lost of productivity and need of improvement in the operational planning. The skidder equipped only with rubber tires showed higher productivity and lower production cost in the longest extraction distances, caused by the higher operating speed of the machine.Keywords: Timber extraction; wheel types; operating efficiency

Fast processing of grid maps using graphical multiprocessors

Grid mapping is a very common technique used in mobile robotics to build a continuous 2D representation of the environment useful for navigation purposes. Although its computation is quite simple and fast, this algorithm uses the hypothesis of a known robot pose. In practice, this can require the re-computation of the map when the estimated robot poses change, as when a loop closure is detected. This paper presents a parallelization of a reference implementation of the grid mapping algorithm, which is suitable to be fully run on a graphics card showing huge processing speedups (up to 50×) while fully releasing the main processor, which can be very useful for many Simultaneous Localization and Mapping algorithms

Multi-wavelength observations of the transitional millisecond pulsar binary XSSJ12270-4859

We present an analysis of X-ray, Ultraviolet and optical/near-IR photometric data of the transitional millisecond pulsar binary XSSJ12270-4859, obtained at different epochs after the transition to a rotation-powered radio pulsar state. The observations, while confirming the large-amplitude orbital modulation found in previous studies after the state change, also reveal an energy dependence of the amplitudes as well as variations on time scale of months. The amplitude variations are anti-correlated in the X-ray and the UV/optical bands. The average X-ray spectrum is described by a power law with \Gamma index of 1.07(8) without requiring an additional thermal component. The power law index \Gamma varies from 1.2 to 1.0 between superior and inferior conjunction of the neutron star. We interpret the observed X-ray behaviour in terms of synchrotron radiation emitted in an extended intrabinary shock, located between the pulsar and the donor star, which is eclipsed due to the companion orbital motion. The G5 type donor dominates the UV/optical and near-IR emission and is similarly found to be heated up to ? 6500K as in the disc state. The analysis of optical light curves gives a binary inclination 46 < i < 65deg and a mass ratio 0.11 < q <0.26. The donor mass is found to be 0.15 < M2 < 0.36Msun for a neutron star mass of 1.4Msun. The variations in the amplitude of the orbital modulation are interpreted in terms of small changes in the mass flow rate from the donor star. The spectral energy distribution from radio to gamma-rays is composed by multiple contributions that are different from those observed during the accretion-powered state.Comment: 10 pages, 8 figures, 1 table Accepted for publication in Monthly Notices Royal Astronomical Society, Main Journa