1,720,982 research outputs found
Memory requirements and computation times for implementing the reduced consensus algorithm
No full textNew Prospects of Optical Wireless Communication Systems Exploiting VCSEL-Based Transmitters
Full text linkIn the last decades, Vertical Cavity Surface Emitting Lasers (VCSELs) emerged as a dominant technology for shortreach high-data rate networks thanks to several advantageous features. These include low power consumption, high modulation speeds, low costs, and compact size. More recently, these inherent characteristics of the VCSELs have also made them exceptionally suited for a variety of Optical Wireless Communication (OWC) applications, particularly for short-distance links, up to a few meters. This paper reviews a range of new and promising applications for VCSELs within emerging OWC domains: Data Centers (DCs), space, and harsh environment. We present and discuss different VCSEL-based OWC systems that were designed, implemented, and tested in these emerging scenarios. For the DCs scenario, we present a novel approach to establish OWC links able to reach data rates up to 40 Gbit/s with a single VCSEL. In the space environment, innovative OWC systems can support data communication among electronic elements placed in line-of-sight outside the spacecraft or inside a small satellite. VCSELs can be also exploited for data transmission in the very harsh environment of high-energy physics experiments. Here, a 10 Gbit/s OWC system was designed for the Board-to-Board (B2B) link in High Energy Physics (HEP) experiments. Since space and HEP applications exhibit extreme conditions, the OWC systems and, particularly, the VCSELs were tested to assess their behavior under strong mechanical, thermal, and radiation stress
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
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
Transporting MIL-STD-1553 Signals by Means of Optical Wireless Interfaces
No full textToday, the on-board Spacecraft (SC) communication requires an impressive network of massive wires, both in flight and in the Assembly Integration and Test (AIT) phase. Here, we present the design and the experimental characterization of novel Optical Wireless Communication (OWC) transceivers compatible with MIL-STD-1553B, which is the shared bus predominantly deployed in SCs. Each transceiver works as an interface that transports the bipolar Manchester-coded signal by converting it to/from the optical domain. These OWC interfaces can effectively reduce the overall weight and cost of the SC and can also largely decrease the AIT time. Since they are fully analog and do not need any microprocessors or Digital Signal Processing, they have a small footprint and a very low power consumption. We initially characterize the transceivers using a non-return-to-zero (NRZ) signal, then we used them to replace a cable and connect a pair of test units, transmitting MIL-STD-1553B signals: the measurements show that our solution has a good power budget (+65dB), which will allow the interoperability with MIL-STD-1553B boards in a wide range of scenarios. Furthermore, it is realized by means of commercially available components; it could also be implemented by using proven space-graded devices
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