1,720,989 research outputs found
Run-time compilation techniques for wireless sensor networks
No full textWireless sensor networks research in the past decade has seen substantial initiative, support and potential. The true adoption and deployment of such technology is highly dependent on the workforce available to implement such solutions. However, embedded systems programming for severely resource constrained devices, such as those used in typical wireless sensor networks (with tens of kilobytes of program space and around ten kilobytes of memory), is a daunting task which is usually left for experienced embedded developers.Recent initiative to support higher level programming abstractions for wireless sensor networks by utilizing a Java programming paradigm for resource constrained devices demonstrates the development benefits achieved. However, results have shown that an interpreter approach greatly suffers from execution overheads. Run-time compilation techniques are often used in traditional computing to make up for such execution overheads. However, the general consensus in the field is that run-time compilation techniques are either impractical, impossible, complex, or resource hungry for such resource limited devices.In this thesis, I propose techniques to enable run-time compilation for such severely resource constrained devices. More so, I show not only that run-time compilation is in fact both practical and possible by using simple techniques which do not require any more resources than that of interpreters, but also that run-time compilation substantially increases execution efficiency when compared to an interpreter
Demo Abstract: Run-time Compilation of Bytecode in Wireless Sensor Networks
No full textRecent work on virtual machines for wireless sensor networks has demonstrated the benefits of using a Java programming paradigm for resource constrained sensor networks. Results have shown that a virtual machine approach greatly suffers from interpretation overheads. We present run-time compilation of bytecode which leverages from a compact platform independent bytecode application encoding as well as an efficient program execution platform by converting bytecode to native code in situ
DPICache: A Distributed Program Image Cache for Wireless Sensor Networks
No full textWireless sensor networks, like other computing platforms, require software updates from time to time due to software bugs, new functionality, better understanding of the surrounding environment or new applications. Physically connecting to and reprogramming each node is usually not feasible and often impossible. A number of wireless code distribution and reprogramming techniques have been presented in recent years. In this paper we present a novel technique to efficiently update any nodes that were lost during programming periods. Our experiments demonstrate a 57% decrease of bytes sent over the air when updating nodes that previously missed updates
Run-time Compilation of Bytecode in Sensor Networks
No full textRecent work on virtual machines for wireless sensor networks has demonstrated the benefits of using a Java programming paradigm for resource constrained sensor networks. Results have shown that a virtual machine approach greatly suffers from interpretation overheads. In this paper, we present run-time compilation of bytecode in wireless sensor networks which leverages from both a compact platform independent bytecode program representation as well as a native execution platform for efficient execution of code. Our results show that run-time compilation provides a substantial decrease in execution overheads when compared with an interpreter
A Dynamic Size Distributed Program Image Cache for Wireless Sensor Networks
No full textReprogramming node software over-the-air is an essential requirement in many wireless sensor network applications due to the inaccessibility of the deployed sensor nodes. Transmitting whole software images consumes a high amount of energy in proportion to updates, especially when they are small in size. Incremental updates have addressed this; however introduce the potential of a sensor node becoming out of sync when it misses an update. In this paper we present a dynamic size distributed program image cache that provides increased efficiency in reprogramming out of sync nodes and multi-purpose wireless sensor networks
Field deployment of low power high performance nodes
Full text linkWhen deploying a sensor network into a harsh environment the need for high levels of fault tolerance and maximising the usage of available resources become extremely important. This has been achieved by implementing a highly fault tolerant system based on our Gumsense boards. These combine an ARM-based Linux system with an MSP430 for sensing and power-control. It also allows for dynamic schedule modifications based on the available power and can be synchronised with other systems without relying on direct communication, autonomous behaviour in case of total communications failure is also supported. A deployment on Vatnajökull, the largest ice-cap in Europe, has provided a longterm test for the systems and revealed strengths and weaknesses in the design decisions
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
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