1,720,956 research outputs found
Playfair crib validation as a constraint satisfaction problem
Full text linkThis paper shows how a crib1 for a Playfair enciphered message can be seen as a constraint satisfaction problem. This problem can then be solved with standard constraint programming tools. The solution will tell whether the crib is possible, and if so, can list all possible Playfair keys that would result in the given crib
The TICOM DF-114 Cryptanalytic Device - A Theory of Operation and Computer Simulation
No full textThe M-209 cipher machine was used extensively by the U.S.A. during WorldWar II. It is known that German cryptanalysts under certain circumstances were able to decipher M-209 enciphered messages using pen-and-paper techniques. A German wartime document found by the allies’ Target Intelligence Committee (TICOM) in 1947 describes a electromechanical machine that supposedly could be used as an aid when breaking M-209 enciphered messages. The document, designated DF-114 by TICOM, is quite technical but does not describe how the device would work. This paper suggests a theory of how the device could have been used, and by creating a computer simulation of the device described in DF-114 explores the viability of the theory
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
A WW2 device for breaking the M-209 encryption machine
Full text linkAccording to an eyewitness report by German engineer Reinold Weber published in 2004, a German cryptanalysis unit broke the U.S. cipher machine M-209 in the Second World War. For this purpose, the specialists involved built an electromechanical machine (“Weber machine”), which included binary logic and bore some resemblance with the Turing Bombe. In previously unpublished documents contained in the TICOM reports, information can be found about a cryptanalysis device that is probably identical with the Weber machine. Based on the said sources, this paper describes what is known about this deciphering technology
Analysis of the US Navy Cryptanalytic Bombe Schematics and Simulation of Selected Circuits
Full text linkThis paper analyses several sheets of schematic circuit diagrams and drawings of the US Navy Cryptanalytic Bombe which was used as part of the process of deciphering German Enigma encrypted messages. The functionality of selected circuits is verified through simulation and some circuits are analysed in-depth
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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