1,721,547 research outputs found
Communications and Multimedia Security: Proceedings of the 13th IFIP TC 6/TC 11 international conference on Communications and Multimedia Security
No full textCatalytic production of petrochemical products from bio-alcohols
Full text linkLarge-scale petrochemicals are typically produced using petroleum olefins as
a feedstock. The desire to move toward a sustainable and environmentally
friendly chemical industry has lead to interest in the use of bio-derived
feedstocks such as alcohols which are currently being produced on an
increasingly large scale by fermentation or from synthesis gas.
The research investigated the direct catalytic production of ethylene,
acetaldehyde, ethylene dichloride (EDC), and ethylene oxide (EO) from
ethanol. Two approaches were considered: a) the use of a bi-functional
catalyst that combines the dehydration capability with ethylene conversion
and b) the use of a double catalytic bed system where ethanol was dehydrated
over the 1st bed and the product ethylene was converted over the 2nd bed to
yield the desired petrochemical product.
The dehydration of ethanol was carried out over several zeolites at different
operating temperatures, producing mainly ethylene and diethyl ether.
The catalytic selective oxidation of ethanol was tested over silver and/or
copper compounds supported on several zeolites. The effects of operating
conditions, metal loading, and zeolite acidity were determined. High
selectivity to acetaldehyde was achieved. Unfortunately, the direct production
of EO from ethanol could not be achieved.
The catalytic oxychlorination of ethanol was investigated using CuCl2 as the
active compound and zeolites were used as either a support or as a pre-bed.
EDC was produced via ethylene oxychlorination as well as the
oxychlorination and disproportionation of ethyl chloride. The effects of
operating conditions and CuCl2 loading were determined. Higher EDC yield
was achieved over the dual-bed system compared to the bi-functional catalyst
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
Secure Role-based Messaging
Full text linkThis paper describes a secure role based messaging system design based on the use of X.509 Attribute Certificates for holding user roles. Access to the mes-sages is authorised by the PERMIS Privilege Management Infrastructure, a pol-icy driven role based access control (RBAC) infrastructure, which allows the assignment of roles to be distributed between trusted issuing authorities, and allows a change of access control policy at runtime. Messages can be sent by roles and users, and can be sent to roles and users. Messages are secure in their exchange between senders and recipients. Details of the security and messaging design are presented
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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe 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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