1,721,308 research outputs found
A low cost solution to cloning and authentication based on a lightweight primitive
No full textThis paper proposes a solution to address the issue of authentication to prevent counterfeiting in a low cost RFID based system based on using a lightweight primitive, Physically Unclonable Functions. © 2008 Springer-Verlag Berlin Heidelberg.Damith C. Ranasinghe, Srinivas Devadas, and Peter H. Col
Oblivious Routing in On-Chip Bandwidth-Adaptive Networks
Full text linkOblivious routing can be implemented on simple router hardware, but network performance suffers when routes become congested. Adaptive routing attempts to avoid hot spots by re-routing flows, but requires more complex hardware to determine and configure new routing paths. We propose on-chip bandwidth-adaptive networks to mitigate the performance problems of oblivious routing and the complexity issues of adaptive routing.In a bandwidth-adaptive network, the bisection bandwidth of a network can adapt to changing network conditions. We describe one implementation of a bandwidth-adaptive network in the form of a two-dimensional mesh with adaptive bidirectional links, where the bandwidth of the link in one direction can be increased at the expense of the other direction. Efficient local intelligence is used to reconfigure each link, and this reconfiguration can be done very rapidly in response to changing traffic demands. We compare the hardware designs of a unidirectional and bidirectional link and evaluate the performance gains provided by a bandwidth-adaptive network in comparison to a conventional network under uniform and bursty traffic when oblivious routing is used
An integrable low cost hardware random number generator
No full textA hardware random number generator is different from a pseudo-random number generator; a pseudo-random number generator approximates the assumed behavior of a real hardware random number generator. Simple pseudo random number generators suffices for most applications, however for demanding situations such as the generation of cryptographic keys, requires an efficient and a cost effective source of random numbers. Arbiter-based Physical Unclonable Functions (PUFs) proposed for physical authentication of ICs exploits statistical delay variation of wires and transistors across integrated circuits, as a result of process variations, to build a secret key unique to each IC. Experimental results and theoretical studies show that a sufficient amount of variation exits across IC"s. This variation enables each IC to be identified securely.It is possible to exploit the unreliability of these PUF responses to build a physical random number generator.Damith C. Ranasinghe, Daihyun Lim, Srinivas Devadas, Behnam Jamali, Zheng Zhu and Peter H. Col
Exploiting metastability and thermal noise to build a re-configurable hardware random number generator
No full text©2005 COPYRIGHT SPIE--The International Society for Optical Engineering.While pseudo random number generators based on computational complexity are widely used for most of cryptographic applications and probabilistic simulations, the generation of true random numbers based on physical randomness is required to guarantee the advanced security of cryptographic systems. In this paper we present a method to exploit manufacturing variations, metastablity, and thermal noise in integrated circuits to generate random numbers. This metastability based physical random number generator provides a compact and low-power solution which can be fabricated using standard IC manufacturing processes. Test-chips were fabricated in TSMC 0.18um process and experimental results show that the generated random bits pass standard randomness tests successfully. The operation ofthe proposed scheme is robust against environmental changes since it can be re-calibrated to new environmental conditions such as temperature and power supply voltage.Daihyun Lim, Damith C. Ranasinghe, Srinivas Devadas, Behnam Jamali, Derek Abbott, and Peter H. Col
Mathematics for Computer Science (SMA 5512)
No full textThis is an introductory course in Discrete Mathematics oriented toward Computer Science and Engineering. The course divides roughly into thirds: Fundamental concepts of Mathematics: definitions, proofs, sets, functions, relations. Discrete structures: modular arithmetic, graphs, state machines, counting. Discrete probability theory. This course was also taught as part of the Singapore-MIT Alliance (SMA) programme as course number SMA 5512 (Mathematics for Computer Science). Contributors Srinivas Devadas Lars Engebretsen David Karger Eric Lehman Thomson Leighton Charles Leiserson Nancy Lynch Santosh Vempal
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
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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