13,317 research outputs found
Exploiting log files in video retrieval
While research into user-centered text retrieval is based on mature evaluation methodologies, user evaluation in multimedia retrieval is still in its infancy. User evaluations can be expensive and are also often non-repeatable. An alternative way of evaluating such systems is the use of simulations. In this poster, we present an evaluation methodology which is based on exploiting log files recorded from a user-study we conducted
Analysis and correction of the magnetic field effects in the Hybrid Photo-Detectors of the RICH2 Ring Imaging Cherenkov detector of LHCb
The Ring Imaging Cherenkov detectors of the LHCb experiment at the Large
Hadron Collider at CERN are equipped with Hybrid Photo-Detectors. These vacuum
photo-detectors are affected by the stray magnetic field of the LHCb magnet,
which degrades their imaging properties. This effect increases the error on the
Cherenkov angle measurement and would reduce the particle identification
capabilities of LHCb. A system has been developed for the RICH2 Ring Imaging
Cherenkov detector to perform a detailed characterisation of the magnetic
distortion effects. It is described, along with the methods implemented to
correct for these effects, restoring the optimal resolution.Comment: 16 pages, 11 figure
Methodology of Construction of an Algorithm for the Systemic Learning of First Semester Students of the TICs Subject
Algorithms have become the primary source to start programming. Particularly, making an algorithm from a given problem and converting it into a program is of great importance for analysts, technologists, and computer engineers, that is why this article aims to give a clear idea of how to develop an algorithm for any given problem. The objective of this work was to develop a methodology that is not so complex and that allows our students to perform the algorithm, pseudo-code, flow diagram and finally be able to carry out the program. The tests carried out show that the methodology used gives good results, achieving a significant improvement in the learning of students in the first semester of industrial engineering.
Keywords: algorithms, flow diagrams, program, programming, software engineerin
CCSD(T) study of the far-infrared spectrum of ethyl methyl ether
10 pages, 5 figures, 9 tables.Band positions and intensities for the far-infrared bands of ethyl methyl ether are variationally determined from a three-dimensional (3D) potential energy surface calculated with CCSD(T)/cc-pVTZ theory. For this purpose, the energies of 181 selected geometries computed optimizing 3n−9 parameters are fitted to a 3D Fourier series depending on three torsional coordinates. The zero point vibrational energy correction and the search of a correct definition of the methyl torsional coordinate are taken into consideration for obtaining very accurate frequencies. In addition, second order perturbation theory is applied on the two molecular conformers, trans and cis-gauche, in order to test the validity of the 3D model. Consequently, a new assignment of previous experimental bands, congruent with the new ab initio results, is proposed. For the most stable trans-conformer, the 30, 29, and 28 fundamental transitions, computed at 115.3, 206.5, and 255.2 cm−1, are correlated with the observed bands at 115.4, 202, and 248 cm−1. For the cis-gauche the three band positions are computed at 91.0, 192.5, and 243.8 cm−1. Calculations on the −d3 isotopomer confirm our assignment. Intensities are determined at room temperature and at 10 K. Structural parameters, potential energy barriers, anharmonic frequencies for the 3n−9 neglected modes, and rotational parameters (rotational and centrifugal distortion constants), are also provided.This work has also been supported by the Ministerio de
Educación of Spain, Grant No. AYA2005-00702 Plan Nacional
I+D+I 2004–2007 , CONACYT of Mexico, Grant
No. 58728 CoNaCYT, and Computing resources of CESGA.Peer reviewe
Experiment Investigating the Connection between Weak Values and Contextuality
Weak value measurements have recently given rise to a large interest for both
the possibility of measurement amplification and the chance of further quantum
mechanics foundations investigation. In particular, a question emerged about
weak values being proof of the incompatibility between Quantum Mechanics and
Non-Contextual Hidden Variables Theories (NCHVT). A test to provide a
conclusive answer to this question was given in [M. Pusey, Phys. Rev. Lett.
113, 200401 (2014)], where a theorem was derived showing the NCHVT
incompatibility with the observation of anomalous weak values under specific
conditions. In this paper we realize this proposal, clearly pointing out the
strict connection between weak values and the contextual nature of Quantum
Mechanics.Comment: 5 pages, 4 figure
Planck Low Frequency Instrument: Beam Patterns
The Low Frequency Instrument on board the ESA Planck satellite is coupled to
the Planck 1.5 meter off-axis dual reflector telescope by an array of 27
corrugated feed horns operating at 30, 44, 70, and 100 GHz. We briefly present
here a detailed study of the optical interface devoted to optimize the angular
resolution (10 arcmin at 100 GHz as a goal) and at the same time to minimize
all the systematics coming from the sidelobes of the radiation pattern. Through
optical simulations, we provide shapes, locations on the sky, angular
resolutions, and polarization properties of each beam.Comment: On behalf of the Planck collaboration. 3 pages, 1 figure. Article
published in the Proceedings of the 2K1BC Experimental Cosmology at
millimetre wavelength
Efficiently Clustering Very Large Attributed Graphs
Attributed graphs model real networks by enriching their nodes with
attributes accounting for properties. Several techniques have been proposed for
partitioning these graphs into clusters that are homogeneous with respect to
both semantic attributes and to the structure of the graph. However, time and
space complexities of state of the art algorithms limit their scalability to
medium-sized graphs. We propose SToC (for Semantic-Topological Clustering), a
fast and scalable algorithm for partitioning large attributed graphs. The
approach is robust, being compatible both with categorical and with
quantitative attributes, and it is tailorable, allowing the user to weight the
semantic and topological components. Further, the approach does not require the
user to guess in advance the number of clusters. SToC relies on well known
approximation techniques such as bottom-k sketches, traditional graph-theoretic
concepts, and a new perspective on the composition of heterogeneous distance
measures. Experimental results demonstrate its ability to efficiently compute
high-quality partitions of large scale attributed graphs.Comment: This work has been published in ASONAM 2017. This version includes an
appendix with validation of our attribute model and distance function,
omitted in the converence version for lack of space. Please refer to the
published versio
The Planck Low Frequency Instrument
The Low Frequency Instrument (LFI) of the "Planck Surveyor" ESA mission will
perform high-resolution imaging of the Cosmic Microwave Background anisotropies
at four frequencies in the 30-100 GHz range. We review the LFI main scientific
objectives, the current status of the instrument design and the on-going effort
to develop software simulations of the LFI observations. In particular we
discuss the design status of the PLANCK telescope, which is critical for
reaching adequate effective angular resolution.Comment: 10 pages, Latex (use epsfig.sty); 4 Postscript figures; Astrophys.
Lett & Comm, in press. Proc. of the Conference: "The Cosmic Microwave
Background and the Planck Mission", Santander, Spain, 22-25 June 199
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