1,721,021 research outputs found
Identification of materials hidden inside a container by using the 14 MeV tagged neutron beam
No full textThe results of the experiments aiming to confirm the presence of explosive inside the container by using the 14 MeV tagged neutron beam are presented. Measurements were performed with paper, sugar, flour, fertilizer, tobacco and explosive (Semtexla) as target material placed in the center of an empty container. Additional measurements were done with paper and explosive placed in the center of the container filled with the iron matrix of 0.2 gcm(-3) density and with the paper target shielded by the 5.1 cm thick iron shield. The results of time of flight measurements and gamma ray spectra obtained by 14 MeV tagged neutron beam have showed that investigated materials could be well distinguished in the triangle plot with coordinates being the number of counts in the carbon peak, the number of counts in oxygen peak and the number of counts in transmitted neutron peak. By using such presentation we have been able to separate paper from Semtexla, both hidden inside the 0.2 gcm-3 iron matrix. We have also been able to confirm the presence of 64.4 kg of paper behind the 5.1 cm thick iron shield corresponding to the range of 300 keV X-rays
Sistema prototipale per la scansione automatica ad ultrasuoni della mammella
No full textL’esame ad ultrasuoni riveste un ruolo importante nello screening della mammella, in particolare nel caso di pazienti con seno denso. È stato realizzato un sistema che permette di effettuare una scansione 3D automatica del seno utilizzando un qualsiasi tipo di sonda 2D lineare convenzionale ad ultrasuoni comunemente presente nei centri di diagnostica senologica. La localizzazione della sonda permette di ricostruire in modo preciso il volume del seno scansionato. L’idea del sistema proposto nasce dall’interesse di confrontare in modo quantitativo le informazioni morfologiche ottenute dall’esame di Tomosintesi con l’informazione ecografica mediante una registrazione elastica multimodale delle immagini tridimensionali
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
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
Monte Carlo analysis of tagged neutron beams for cargo container inspection
No full textFast neutrons produced via D + T reactions and tagged by the associated particle technique have been recently proposed to inspect cargo containers. The general characteristics of this technique are studied with Monte Carlo simulations by determining the properties of the tagged neutron beams as a function of the relevant design parameters (energy and size of the deuteron beam, geometry of the charged particle detector). Results from simulations, validated by experiments, show that the broadening of the correlation between the a-particle and the neutron, induced by kinematical as well as geometrical (beam and detector size) effects, is important and limits the dimension of the minimum voxel to be inspected. Moreover, the effect of the container filling is explored. The material filling produces a sizeable loss of correlation between a-particles and neutrons due to scattering and absorption. Conditions in inspecting cargo containers are discussed
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
Detection of hidden explosives by using tagged neutron beams: Status and perspectives
No full textNon-destructive inspections have been simulated in laboratory conditions by using our tagged neutron inspection system (TNIS), using YAP:Ce scintillators to tag the neutron beam and an array of BaF2 crystals to detect the gamma-rays. The system has been operated up to 2 x 10(8) neutron/s. Further developments of the TNIS concept are discussed in the light of our current projects for cargo container inspections
Detection of hidden explosives by using tagged neutron beams with sub-nanosecond time resolution
No full textNon-destructive inspection of luggage has been simulated in laboratory conditions by using a 14 MeV tagged neutron beam and BaF2 scintillation detectors (Tagged Neutron Inspection System, TNIS). The tagged, neutron beam is produced by detecting the associated alpha particle emitted in the D+T reaction by means of a YARCe scintillator. The TNIS intrinsic time resolution has been measured to be delta t = 0.9 ns [FWHM], which allows inspection of a minimum voxel of 5 cm depth along the neutron flight path. This characteristic is demonstrated by identifying graphite and water samples hidden inside a hard plastic suitcase filled with background material. Finally, explosive devices such as small anti-personnel or anti-tank landmines have been inspected when, placed inside the suitcase. In the case of relatively large explosive objects such as an anti-tank landmine, the system is capable of testing directly the TNT charge inside the device, separating this material from the external plastic case-Further developments of the TNIS concept are discussed
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