1,721,062 research outputs found
Sistemi di propulsione ibridi per mezzi subacquei: una applicazione della macchina di Stirling
No full textReal-time dense stereo on a personal computer
No full textThis paper presents a stereo algorithm that enables real time dense disparity measurements on standard personal computers. Unlike many other dense stereo algorithms, which are based on two matching phases, the proposed algorithm relies on a single matching phase and allows for rejecting unreliable matches by exploiting violations of the uniqueness constraint and analysing the behaviour of the correlation scores. The overall algorithm has been carefully optimised using very efficient calculation schemes and deploying massively the SIMD parallel processing capabilities available nowadays in state-of-the-art general purpose microprocessors. The paper describes the algorithm and the optimisation strategies, and provides experimental results obtained on stereo pairs with ground-truth as well as execution times measurements
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Variations on the Author
Get PDF“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
Get PDFWe 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
Dense stereo based on the uniqueness constraint
No full textThe paper presents the matching core of a stereo algorithm suitable to real-time applications. Unlike most area-based algorithms, the proposed approach relies on a single matching phase (i.e. do not include the check for left-right consistency). Unreliable disparity measuremnts are primarly detected on the basis of the violation of the uniqueness constraint. In order to further improve the reliability of the matches we enforce additional contraints based on the behaviour of the error function that can be veryfied at a very small computational cost. Experimental results show that the proposed approach provides reliable disparity measurements and that it is significantly fast. © 2002 IEEE
Quantitative evaluation of area-based stereo matching
No full textThis paper presents a quantitative evaluation of two area-based stereo matching approaches aimed at real-time applications. The former approach follows a standard scheme based on a double matching phase (DMP) and aimed at rejecting unreliable disparities by enforcing the left-right consistency constraint. This approach is representative of several implementations known in literature. The latter approach, proposed recently, relies on a single matching phase (SMP) and rejects unreliable matches by detecting violations of the uniqueness constraints. We review first the two approaches and analyse their differences. Successively, we provide quantitative results, using standard stereo pairs with ground truth, aimed at evaluating and comparing the two approaches in terms of matching reliability and speed
Numerical modelling and performance maps of a printed circuit heat exchanger for use as recuperator in supercritical CO2 power cycles
Get PDFIn heat to power systems with CO2 as working fluid in the supercritical state (sCO2), heat exchangers account for nearly 80% of the capital expenditure. Therefore, improved design, materials and manufacturing methodologies are required to enable the economic feasibility of the sCO2 technology. In this study, a comparison of different modelling methodologies for Printed Circuit Heat Exchangers (PCHE) is proposed to identify strengths and weaknesses of both the approaches. The elementary heat transfer unit of a PCHE recuperator for sCO2 applications is firstly modelled using 1D and 3D CFD methodologies respectively; implemented in GT-SUITE and ANSYS FLUENT software. After the comparison in terms of heat transfer performance and pressure drops, the 1D approach is used to model a 630kW PCHE recuperator. The PCHE model calibration on the design point, followed by its validation against off-design operating points provided by the manufacturer, eventually enabled to broaden the simulation spectrum and retrieve performance maps of the device. The CFD models comparison shows a good agreement between temperature profiles. However, the local heat transfer coefficient, modelled in the 1D approach through the Dittus-Boelter correlation, experiences a +10% offset on the hot side and a -20% on the cold one with respect to the 3D CFD calculations. Besides, the performance maps of the full scale PCHE recuperator show that the maximum temperature of the hot stream impose a greater influence than the maximum pressure of the cold one in terms of overall heat transfer coefficient. Nonetheless, both these operating parameters contribute to affect the heat exchanger effectiveness.The Engineering and Physical Sciences Research Council (EPSRC) of the UK and the European Union’s Horizon 2020 research and innovation programme
The influence of real gas thermodynamics on simulations of freely propagating flames in methane/oxygen/inert mixtures
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