1,721,167 research outputs found
Transputer implementation of systolic arrays for model reduction
No full textIn control theory the dynamics representing a physical system to be controlled is analyzed in terms of a model built up from a mathematical description of the system components. Unfortunately the resulting model can have high or infinite dimensional state equations, so it is often necessary from a practical and computational viewpoint to find a reduced model of the system which mimics closely the behaviour of the high order system. The technique for producing these simplified descriptions is termed model reduction and a number of methods are known. The author is interested in applying computational parallelism to the generation of reduced models to provide an acceleration mechanism for use in a CAD environment. In the paper the author develops systolic algorithms for simple single input-output control problems and implements them on a network of transputers. The performance of this network is then evaluated with respect to a sequential algorithm for the same problems. Finally, the author points out that systolic arrays are normally considered as special purpose methods geared towards exploiting VLSI techniques
Mapping a class of run-time dependencies onto regular arrays
No full textThe production of regular computations using algorithmic engineering techniques is beginning to play an important role in the synthesis of massively parallel and VLSI processor arrays. The author widens the class of algorithms that can be formally synthesized by introducing a mapping theorem for a class of algorithms with run-time dependencies. The technique is illustrated by deriving uniform recurrences for the so-called knapsack problem, the resulting systolic array is known to be optimal
Transputer implementation of systolic arrays for model reduction
No full textThe author develops a unified bidirectional linear systolic array for performing model reduction of a feedback control system using continued fractions. The array is capable of computing the 1st, 2nd and 3rd Cauer forms of the fraction and their associated inverses as well as the Routh stability criterion. Timing graphs are presented to indicate the speed-up obtained on five transputers for common problem ranges
Sorting without exchanges on a bit-serial systolic array
No full textThe author considers, a number of bit-serial systolic designs for ordering a list of n elements without 'on-the-fly' exchanges are considered. The algorithms require 4n+p+k bit steps where p=log2 n and k is the number of bits required to encode all the possible elements. The arrays require O(n(p+k)) bit cells with a complexity roughly the same as that of a full adder and between max (p,k) and p+k input/output pins. The input to the array is the list to be sorted and an auxiliary vector whose elements have bit length p. The output is the list itself and the auxiliary vector, which is updated to produce pointers to the correct position of each element in the ordered list
CAD tools for the automatic synthesis of parallel algorithms in control
No full textThe paper is to promotes the concept that the design of parallel control algorithms can be pursued by employing algorithm engineering. It is demonstrated that a particular class of algorithms, control laws based on systems of recurrence equations with time as an independent variable, can be engineered at an algorithmic level to exploit parallelism. The problem of engineering an algorithm so that it models certain design objectives such as minimum latency, pipelined data flow etc. is considered. The author considers control system design as a 2-stage process. The levels are distinct and separated into conventional control system and parallel algorithm design respectively. The whole design process embraces a fusion between control theory and the theory of algorithms requiring skills in both mathematics and computer science. A number of seemingly different methods of synthesis are considered. They have considerable overlap and can in fact be combined to provide a unified and viable methodology for the systematic and reasoned mapping of control algorithms onto parallel architectures. It is well known that control elements can be implemented via physical devices or through software. Furthermore control systems are inherently parallel in nature
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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