102,773 research outputs found
Security Framework for Children’s Safety Watches
No full textGeorgia Castignani, Narayan Shanmuganathan, Nooragha Sharifi, Matthew Sorell and Richard Matthew
A Method for Vibration and Harshness Analysis Based on Indoor Testing of Automotive Suspension Systems
No full textThe paper presents a method for the indoor testing of road vehicle suspension systems. A suspension is positioned on a rotating drum which is located in the Laboratory for the Safety of Transport at Politecnico di Milano. Special six-axis load cells have been designed and used for measuring the forces/moments acting at each suspension-chassis joints. The forces/moments, wheel accelerations, displacements are measured up to 100 Hz. Two different types of test can be performed. The tire/wheel unbalance effect on the suspension system behavior (Vibration and Harshness, VH) has been analyzed by testing the suspension system from zero to the vehicle maximum speed on a flat surface and by monitoring the forces transmitted to the chassis. In the second kind of test, the suspension system has been excited as the wheel passes over different cleats fixed on the drum.
By analyzing the forces and the acceleration measured on the suspension system, a set of performance indexes has been derived from the analysis of the data both in time and frequency domain. A simple mathematical model of the tire/suspension system has been derived and validated to analyze the relative effect of the road irregularity and of the tire/wheel unbalance on an actual suspension dynamic behavior. It has been shown, that the direct measurement of the forces and moments at the suspension-chassis joints is an effective way for understanding the vibration and harshness suspension performances
Black-hole mass estimates for a homogeneous sample of bright flat-spectrum radio quasars
No full textWe have selected a complete sample of flat-spectrum radio quasars (FSRQs) from the WMAP 7-yr catalog within the SDSS area, all with measured redshift, and have compared the black hole mass estimates based on fitting a standard accretion disk model to the `blue bump' with those obtained from the commonly used single epoch virial method. The sample comprises 79 objects with a flux density limit of 1 Jy at 23 GHz, 54 of which (68%) have a clearly detected `blue bump'. Thirty-four of the latter have, in the literature, black hole mass estimates obtained with the virial method. The mass estimates obtained from the two methods are well correlated. If the calibration factor of the virial relation is set to , well within the range of recent estimates, the mean logarithmic ratio of the two mass estimates is equal to zero with a dispersion close to the estimated uncertainty of the virial method. The fact that the two independent methods agree so closely in spite of the potentially large uncertainties associated with each lends strong support to both of them. The distribution of black-hole masses for the 54 FSRQs in our sample with a well detected blue bump has a median value of . It declines at the low mass end, consistent with other indications that radio loud AGNs are generally associated with the most massive black holes, although the decline may be, at least partly, due to the source selection. The distribution drops above , implying that ultra-massive black holes associated with FSRQs must be rare. © ESO, 2013
Le Fortificazioni di Butrinto: nuove acquisizioni topografiche e stratigrafiche.
No full textLa comunicazione che si presenta ha l’obiettivo di illustrare i più recenti dati emersi dalle ricerche archeologiche italo-albanesi all’interno del Parco Nazionale di Butrinto in Albania, ad opera dell’Università di Bologna e dell’Istituto di Archeologia di Tirana. Lo studio muove dalla volontà di raccogliere dati significativi circa le fasi originarie e di sviluppo delle fortificazioni della città antica. La ricerca si è articolata nel riesame della documentazione di scavo edita a partire dalla prima metà del secolo scorso, al fine di avere una raccolta sistematica di tutti gli eventi caratterizzanti la storia degli scavi pertinenti alla cinta muraria. Verrà esposta in particolar modo l’analisi degli elevati condotta nel tratto di mura compreso tra Porta Scea e Porta del Leone, essendo attualmente la porzione meglio conservata e che mostra il maggior numero di interventi costruttivi. Ai dati bibliografici e di archivio, ai risultati emersi dal rilievo topografico e dall’analisi delle fasi edilizie, si affiancano infine quelli provenienti da sondaggi di scavo stratigrafico effettuati nella Campagna 2018. Nel tratto compreso tra il Foro e la Tower Gate sono stati condotti due approfondimenti che hanno interessato in particolar modo l’emplekton delle fortificazioni permettendo di ottenere dati stratigraficamente circostanziati per quanto riguarda diverse fasi di vita e utilizzo della struttura.The aim of this communication is to share the most recent aquisitions of the italo-albanian mission in Butrint national park led by University of Bologna and the Institute of Archaeology of Tirana. The study intended to collect data from the early phase of the fortification of the city, through all their life. The research began with a critical review of all the published data from the first half of the past century in order to have a tidy collection of all the excavation involving the city’s walls. The work focused then on the study of the different building phases that, with the analisys on the wall’s mortar, led to a first chronological reconstruction. The attention will be focused on the wall section between the Lion and Scea Gates, the most preserved and rich in recognizable building actions. The topographical survey of this section, carried out with 3D Laser scanning technology has resulted in the production of ortophoto and front elevation usefull to the study of vertical stratigraphy and the alteration and degradation phenomena. In addition to this data will be shown the one coming from the stratigraphical dig led during the last research campaign (2018). In the section between the Forum and Tower Gate were led two digs that interested the emplekton of the ellenistic walls that added stratigraphical data to the research
AMICO-COSMOS galaxy cluster and group catalogue up to
No full textAims. We present the results of a new galaxy cluster search in the COSMOS field obtained using the Adaptive Matched Identifier of Clustered Objects (AMICO). Our aim was to produce a new cluster and group catalogue up to z = 2 by performing an innovative application of AMICO with respect to previous successful applications to wide-field surveys in terms of depth (down to r < 26.7), small area covered (∼1.69 deg2 of unmasked effective area), and redshift extent. This sample and the comparative analysis we performed with the X-rays, allowed for the calibration of mass-proxy scaling relations up to z = 2 and down to less than 1013 M⊙, and constitutes the basis for the refinement of the cluster model for future applications of AMICO, such as the analysis of upcoming Euclid data.
Methods. The AMICO algorithm is based on an optimal linear matched filter and detects clusters in photometric galaxy catalogues using galaxy location, photometric redshift and, in the simplest case, one galaxy property. We chose to use a single magnitude as the galaxy property, avoiding the explicit use of galaxy colour for the selection of clusters. We used three different magnitudes by performing three independent runs in the r-, Y-, and H-bands using both COSMOS2020 and COSMOS2015 galaxy catalogues. We created a composite visibility mask and cluster models for the signal to detect, and we estimated the noise directly from the data.
Results. We performed a matching of the catalogues resulting from the three runs and merged them to produce a final catalogue that contains 1269 and 666 candidate clusters and groups with S/N > 3.0 and > 3.5, respectively. A total of 490 candidates are detected in all three runs. Most of the detections unmatched between runs have S/N < 3.5, which can be set as a threshold for selecting a more robust sample. We assigned X-ray properties to our detections by matching the catalogue with a public X-ray selected group sample and by estimating, for unmatched detections, the X-ray properties at the location of AMICO candidates using Chandra+XMM-Newton data. There are in total 622 candidate clusters and groups with an X-ray flux estimate. This large sample of candidates with X-ray properties allowed the calibration of the scaling relations between two AMICO mass-proxies (richness and cluster amplitude) and X-ray mass and the study of their redshift dependence for the selection of the most stable photometric bands
A New Method to Search for High-redshift Clusters Using Photometric Redshifts
No full textWe describe a new method (Poisson probability method, PPM) to search for high-redshift galaxy clusters and groups by using photometric redshift information and galaxy number counts. The method relies on Poisson statistics and is primarily introduced to search for megaparsec-scale environments around a specific beacon. The PPM is tailored to both the properties of the FR I radio galaxies in the Chiaberge et al. sample, which are selected within the COSMOS survey, and to the specific data set used. We test the efficiency of our method of searching for cluster candidates against simulations. Two different approaches are adopted. (1) We use two z ~ 1 X-ray detected cluster candidates found in the COSMOS survey and we shift them to higher redshift up to z = 2. We find that the PPM detects the cluster candidates up to z = 1.5, and it correctly estimates both the redshift and size of the two clusters. (2) We simulate spherically symmetric clusters of different size and richness, and we locate them at different redshifts (i.e., z = 1.0, 1.5, and 2.0) in the COSMOS field. We find that the PPM detects the simulated clusters within the considered redshift range with a statistical 1σ redshift accuracy of ~0.05. The PPM is an efficient alternative method for high-redshift cluster searches that may also be applied to both present and future wide field surveys such as SDSS Stripe 82, LSST, and Euclid. Accurate photometric redshifts and a survey depth similar or better than that of COSMOS (e.g., I < 25) are required
Bibliographie Hilarion G. Petzold 1958 – 2009 mit Anhang als Einführung
No full textDieses Archiv enthält die Gesamtbibliographie der Werke des Autors nebst einiger Texte „Über H. G. Petzold“ im Schlussteil der Bibliographie sowie einen Anhang mit einer Einführung in die Architektur des Werkes in seinem wissenslogischen Aufbau als Ausarbeitung seines „Tree of Science Modells“ (2007).This archive contains the complete bibliography of the author and some texts about H. G. Petzold, moreover an epilogue with an introduction to the architecture of the works in its epistemological structure and composition and as an elaborations of Petzold’s „Tree of Science Modell (2007).https://www.fpi-publikation.de/polyloge/01-2009-petzold-h-g-gesamtbibliographie-h-g-petzold-1958-2009-updating-november2009/peerReviewedpublishedVersio
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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