1,721,174 research outputs found
Moore–Penrose approach in the Hough transform framework
No full textLet F(x, a) be a real polynomial in two sets of variables, x and a, that is linear with respect to one of the variable sets, say a. In this paper, we deal with two of the main steps of the Hough transform framework for the pattern recognition technique to detect loci in images. More precisely, we present an algorithmic process, based on the Moore–Penrose pseudo-inverse, to provide a region of analysis in the parameter space. In addition, we state an upper bound for the sampling distance of the discretization of the parameter space region
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Distance bounds of ε-points on hypersurfaces
Full text linkAbstractε-Points were introduced by the authors (see [S. Pérez-Díaz, J.R. Sendra, J. Sendra, Parametrization of approximate algebraic curves by lines, Theoret. Comput. Sci. 315(2–3) (2004) 627–650 (Special issue); S. Pérez-Díaz, J.R. Sendra, J. Sendra, Parametrization of approximate algebraic surfaces by lines, Comput. Aided Geom. Design 22(2) (2005) 147–181; S. Pérez-Díaz, J.R. Sendra, J. Sendra, Distance properties of ε-points on algebraic curves, in: Series Mathematics and Visualization, Computational Methods for Algebraic Spline Surfaces, Springer, Berlin, 2005, pp. 45–61]) as a generalization of the notion of approximate root of a univariate polynomial. The notion of ε-point of an algebraic hypersurface is quite intuitive. It essentially consists in a point such that when substituted in the implicit equation of the hypersurface gives values of small module. Intuition says that an ε-point of a hypersurface is a point close to it. In this paper, we formally analyze this assertion giving bounds of the distance of the ε-point to the hypersurface. For this purpose, we introduce the notions of height, depth and weight of an ε-point. The height and the depth control when the distance bounds are valid, while the weight is involved in the bounds
r-norm bounds and metric properties for zero loci of real analytic functions
No full textWe consider the problem of deciding whether or not a zero locus, X, of multivariate real analytic functions crosses a given r-norm ball in the real n-dimensional affine space. We perform a local study of the problem, and we provide both necessary and sufficient conditions to answer the question. Our conditions derive from the analysis of differential geometric properties of X at the center of the ball. An algorithm to evaluate r-norms distances is proposed
Addressing the potential for improvement of urban building stock: A protocol applied to a Mediterranean Spanish case
Full text linkCurrent plans to combat the environmental global impact of the building sector have encouraged research on sustainable actions for increasing the renovation rate of many buildings whose performance is far from meeting current energy standards. This paper presents a protocol for analysing the existing residential stock towards planning building upgrading actions. A Geographic Information System with building-related data is used to assess the housing stock following a bottom-up approach. The urban study sample is established using several criteria at building level. The potential for improvement of buildings is ascertained using DOE 2.2 energy models which incorporate standard passive strategies to reduce the current primary energy demand and the associated CO2 emissions. The protocol is applied to the existing public housing developments built in the southern Spanish city of Córdoba, under Mediterranean conditions, during the urban expansion period which spanned 1951–1980. The extrapolation of results to the urban study sample shows a 25 % reduction in CO2 emissions and a 40 % decrease in annual energy demand. Furthermore, the impact of typology and position on the energy behaviour of a given building is acknowledged. The benefits achieved aim to help stakeholders in the implementation of energy retrofitting urban plans
New Pliocene Rhinocerotidae findings from the Iberian Peninsula and the revision of the Spanish Pliocene records
No full textA fragmentary mandible from the early Pliocene of the Vera Basin is here investigated to clarify its taxonomic position. The studied specimen is here assigned to Pliorhinus megarhinus, documented in Europe from the latest Miocene to the mid-Pliocene. The morphometrical comparison reveals that this taxon is larger than Stephanorhinus etruscus and S. jeanvireti but overlaps with Dihoplus schleiermacheri. P. megarhinus and D. schleiermacheri differ in some characters of the lower molars, such as the length of the metalophid and the shape of the trigonid in occlusal view, thus allowing new considerations on the Pliocene Spanish rhinocerotine record. According to the results here obtained, three species are at least documented in Span during the Pliocene: P. megarhinus, P. miguelcrusafonti, and S. etruscus. The presence of S. jeanvireti has to be verified and confirmed by further evidence. The presence of Dihoplus schleiermacheri as a relict taxon in the Pliocene of Spain is here discarded
Perturbation of polynomials and applications to the Hough transform
No full textLet and be complex polynomials of the same degree. We provide a new lower bound on the Euclidean distance of points belonging to their zero-loci in terms of Bombieri's norm. We also present a minimization of the Bombieri's norm of the difference , for \lambda\in \C^{^*}. In the real case, we apply the results above in the setting of the Hough transform, a standard technique to detect curves in images, suggesting a Bombieri's norm based recognition algorithm
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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