1,721,043 research outputs found
Template RR Lyrae Hα, Hβ, and Hγ Velocity Curves
Get PDFWe present template radial velocity curves of ab-type RR Lyrae stars constructed from high-precision measurements of Hα, Hβ, and Hγ lines. Amplitude correlations between the Balmer line velocity curves, Johnson V band, and Sloan Digital Sky Survey (SDSS) g- and r-band light curves are also derived. Compared to previous methods, these templates and derived correlations reduce the uncertainty in measured systemic (center-of-mass) velocities of RR Lyrae stars by up to 15 km s^(–1), and will be of particular interest to wide-area spectroscopic surveys such as the SDSS and LAMOST Experiment for Galactic Understanding and Exploration
Open Space Searching with a Mobile Robot for the Purpose of Finding Known Objects
No full textOvaj rad daje opis različitih algoritama za pretraživanje prostora i odabir najpovoljnijeg sa stajališta pokrivenosti prostora i brzine pronalaženja objekata. Ovi algoritmi ispitani su u simulacijama za zadani prostor 100x70m. Efikasnost algoritama je također ispitana za druge tipove prostora (drugačija dimenzija i broj objekata). U svrhu samog pretraživanja koristi se mobilni robot Husky kojim se upravlja po globalnom pozicijskom sustavu (GPS). Također je implementiran sustav za zaobilaženje i detekciju objekata u prostoru.This thesis gives a description of the various search algorithms and selection of the most convenient from the point of space coverage and the speed of finding objects. These algorithms were tested in simulations for the given space of 100x70m. Efficiency algorithms have also been tested for other types of space (different dimensions and number of objects). For the purpose of the search itself, a mobile robot Husky is used which is controlled by using the Global Positioning System (GPS). Also, a system for object detection and avoidance is implemented
Performance Analysis of Multi-robot System based on Private Zones
No full textZa razvijeni decentralizirani algoritam upravljanja višerobotskim sustavom koji koristi koncept privatnih zona obavljen je niz eksperimenata u ROS simulacijskom okruženju uz korištenje RVIZ alata za vizualizaciju. Mijenjajući broj vozila i izgled prostora u kojem se roboti gibaju na sustavan način provodimo analizu učinkovitosti ovog upravljanja na način da mjerimo: ukupan broj obavljenih misija u zadanom vremenu , broj misija pojedinih vozila , prosječno trajanje misija , ujednačenost iskorištavanja vozila, broj sklanjanja s puta drugim vozilima i ostalih pokazatelja učinkovitosti upravljačkog algoritma.For a developed decentralized multi-robot management algorithm which uses the concept of private zones, a series of experiments were performed in the ROS simulation environment using the RVIZ visualization tool. Changing the number of vehicles and the layout of the space in which robots are being deployed in a systematic way, we conduct an analysis of the effectiveness of this management in such a way as to measure: total number of missions performed within a given time, number of individual vehicle missions, average duration of missions, uniformity of utilization of the vehicle and other performance algorithm performance indicators
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
Exploring The Variable Sky With Linear. II. Halo Structure And Substructure Traced By RR Lyrae Stars To 30 kpc
Get PDFWe present a sample of ∼5000 RR Lyrae stars selected from the recalibrated LINEAR data set and detected at heliocentric distances between 5 kpc and 30 kpc over ∼8000 deg2 of sky. The coordinates and light curve properties, such as period and Oosterhoff type, are made publicly available. We analyze in detail the light curve properties and Galactic distribution of the subset of ∼4000 type ab RR Lyrae (RRab) stars, including a search for new halo substructures and the number density distribution as a function of Oosterhoff type. We find evidence for the Oosterhoff dichotomy among field RR Lyrae stars, with the ratio of the type II and I subsamples of about 1:4, but with a weaker separation than for globular cluster stars. The wide sky coverage and depth of this sample allow unique constraints for the number density distribution of halo RRab stars as a function of galactocentric distance: it can be described as an oblate ellipsoid with an axis ratio q = 0.63 and with either a single or a double power law with a power-law index in the range−2 to−3. Consistent with previous studies, we find that the Oosterhoff type II subsample has a steeper number density profile than the Oosterhoff type I subsample. Using the group-finding algorithm EnLink, we detected seven candidate halo groups, only one of which is statistically spurious. Three of these groups are near globular clusters (M53/NGC 5053, M3, M13), and one is near a known halo substructure (Virgo Stellar Stream); the remaining three groups do not seem to be near any known halo substructures or globular clusters and seem to have a higher ratio of Oosterhoff type II to Oosterhoff type I RRab stars than what is found in the halo. The extended morphology and the position (outside the tidal radius) of some of the groups near globular clusters are suggestive of tidal streams possibly originating from globular clusters. Spectroscopic follow-up of detected halo groups is encouraged
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe 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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