322,917 research outputs found
Generalized Hough transform: A useful algorithm for signal path detection
No full textIn early 1998, the Italian SETI program [S. Montebugnoli, et al., SETItalia, A new era in bioastronomy, ASP Conference Series, vol. 213, 2000, pp. 501–504.] started in Medicina with the installation of the Serendip IV 24Million Channel digital spectrometer. This system daily acquires a huge quantity of data to be processed off line, in order to detect possible ETI signals. The programs devoted to this topic are collectively called SALVE 2. Here a natural evolution of a previous effort is presented, which was based on a simple Hough transform and was limited to the detection of short linear tracks in the join time frequency matrix (JTFM) stored by SIV. The new generalized Hough algorithm allows us to detect the sinusoidal tracks by the transformation of the JTF bidimensional Cartesian space (x,y), in the generalized Hough quadridimensional space, where the main vectors are the sine parameters amplitude, frequency, phase and offset. At the end of the paper some results, obtained with the computation of real and simulated JTFM, are shown
Energy consumption comparison of parallel linear systems solver algorithms on HPC infrastructure
No full textOrbit determination of space debris using a bi-static radar configuration with a multiple-beam receiver
No full textIn this work the use of a multi-beaming radar system is analyzed and a possible setup of a closed loop system (i.e. from measurement and data acquisition to orbit determination) is described. The Orbit Determination (OD) algorithms are specialized for a bistatic radar configuration where the Medicina Northern Cross radio-telescope (owned by the University of Bologna-Italy) is considered as a receiver. The Northern Cross is composed of two perpendicular arms: the E/W arm is 564 m long and consists in a single cylindrical antenna with a width of 29.4 m, whereas the N/S arm is made of 64 parallel antennas with a length of 22.6 m and a width of 7.5 m. The collecting area reaches 27,400 sqm and, by considering a complete upgrade of the radar with the installation of new receivers on the focal lines, up to 22,880 possible theoretical independent beams could cover the field-of-view of 55.47 (E/W) deg x 1.8 (N/S) deg. By looking at the sequence of beams that are illuminated, it is thus possible to estimate, with an higher level of detail with respect to the single-beam system, the ground track of the transiting object. Given this peculiar system, tailored orbit determination algorithms have to be developed. The orbit determination algorithm receives as input the data processed by the acquisition system, that digitally assembles measured radar echoes, using Fast Fourier Transform, to provide the signal for each beam. These inputs are the measured Doppler shift, time delay, the illumination time and measured power intensity associated to each beam. By combining these information with the knowledge of beam distribution and pointing it is possible to refine the orbital parameters of known objects or to perform a preliminary OD. A few LEO objects are considered to generate simulated data that are then used to feed the developed OD algorithms. In this way the performances of the algorithms can be tested and the effectiveness of this innovative configuration for space debris measurements, that couples a bistatic radar and a multi-beaming receiver, can be assessed
Diffusive author(s), cohesive author: Analysis of S/N (1994)
No full textThis study indicates the ways in which various aspects of the author(s) are brought forth in Dumb type’s performance art, the S/N production. Previous research has suggested a non-hierarchical organization of Dumb type and the absence of a “privileged author” in Dumb type’s collaborative work, S/N. However, the results that I have investigated from member’s interviews on the creative process of S/N along with my analysis of the recorded images of S/N, indicate a different aspect of the author(s). First, S/N was created through, so to speak, the collective ideas of the members of Dumb type. Further, S/N has at least nine quotations from previous performances, installations, and printed writings, besides the work-in-progress technique. Explicating one of the “author functions” as given by Michel Foucault, each text has plural subjects of the author. However, it has been revealed from members’ interviews that Teiji Furuhashi had a decision-making role in selecting the members’ ideas within the performance. Since then, S/N has had plural subjects of creation; however, Furuhashi is one of the subjects of creation along with the “privileged author.” S/N has plural authors (diffusive authors) yet at the same time, it has a “privileged author,” Teiji Furuhashi (cohesive author)
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe 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
A between-patient disinfection method to control water line contamination and biofilm inside dental units
No full textSEM evaluation of canal wall dentine following use of Mtwo and ProTaper NiTi rotary instruments.
No full textAim To compare using scanning electron microscopy (SEM) root canal walls following instrumentation in vitro with two different rotary NiTi instruments. The hypothesis was that no difference should be observable between the experimental groups in terms of debris on canal walls and surface morphology. Methodology Twenty-four single-rooted human teeth were selected. Two types of NiTi instruments were used, Mtwo (Sweden & Martina, Padova, Italy) and ProTaper (Dentsply Maillefer, Ballaigues, Switzerland). Irrigation for both groups was performed after each instrument change with 5% NaOCl, 3% H2O2 and 17% EDTA solutions. Three different areas (coronal, middle and apical thirds) of the root canal were evaluated using SEM. The canal wall of each sample was assessed and compared using a predefined scale of four parameters, namely, smear layer, pulpal debris, inorganic dentine debris, surface profile. Data were analysed statistically using the Kruskal-Wallis test (ANOVA). Results A statistically significant difference (P<0.01) was found between the apical third and the middle and coronal thirds for both groups. No difference was observable between instrumentation groups. In the apical third canal walls were often contaminated by inorganic debris and by smear layer. In the apical third, the surface profile was affected by uninstrumented regions, comprising dentine depressions and grooves in which predentine was still visible. Conclusion Both instruments produced a clean and debris-free dentine surfaces in the coronal and middle thirds, but were unable to produce a dentine surfaces free from smear layer and debris in the apical third. The presence of deep grooves and depression on dentine walls in the apical third may well explain the presence of less-instrumented areas
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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