1,720,993 research outputs found
Delay tolerance for constrained IPv6 networks
No full textLow power sensor networks have traditionally been regarded as not having the capabilities required to connect them to the internet. New research into the Internet of Things has challenged this concept and is opening up new possibilities for sensor network capabilities. Environmental sensor networks are just one of the areas which will greatly benefit from this connectivity improvement. However, there are many challenges to be solved in order to make full and efficient use of these advancements.One of the major challenges which has been identified is the lack of connectivity when sensors are in low power sleep states. Previous solutions for low power devices have relied on application layer gateways to proxy communications to the sensors, but this restricts the flexibility of the network as it is limited to the capabilities of the proxy. Delay Tolerant Networking (DTN) offers a solution to this problem by allowing sensors to respond and handle communications at their convenience.This thesis presents and evaluates a novel method and implementation of Delay Tolerant Networking using IPv6 extension headers. The proposed DTN extension header is found to have a significantly lower packet size overhead than other DTN protocols. In addition, the protocol and systems to support it are entirely backwards and forwards compatible with the existing internet infrastructure allowing for it to be incorporated into existing deployments. The developed protocol forms a new state of the art for DTN on constrained sensor networks using end to end IP connectivity. Using this, a new range of low power IoT devices can be developed, featuring long battery lives and reliable connectivity
Adding support for delay tolerance to IPv6 networks
No full textAs we continue to connect ever lower power and more power constrained devices to the Internet of Things the problem of maintaining constant end to end connectivity becomes harder. Accepting that continuous end to end connectivity cannot be maintained, we are forced to seek solutions to allow good operating function. Delay Tolerant Networking, an evolution of existing store and forward systems is a candidate for resolving this issue, however, current implementations are not ideal for use in constrained Internet of Things environments. We propose a solution to this by integrating the capabilities of Delay Tolerant Networking into the IP layer, in such a way as to maintain compatibility with existing and future systems and minimising additional overhead. This has been achieved by developing a new IPv6 Hop by Hop option header which contains the information required for messages to be delayed. This solution is then demonstrated to be implementable within the limitations of current Internet of Things hardware
Simulated analysis of connectivity issues for sleeping sensor nodes in the internet of things
No full textThe growth in wireless sensor network deployments requires a move towards more standardised systems to improve compatibility and to reduce development times. The technologies being developed as part of the Internet of Things, such as 6LoWPAN (IPv6 over Low power Wireless Personal Area Networks), can greatly assist with this aim.Connecting low power wireless sensor network devices to the Internet of Things presents certain challenges. One of these challenges is the lack of constant connectivity to sensor nodes with sleep states. Current internet technologies expect that devices are always contactable which is not the case in sensor networks.We simulate and evaluate several solutions to this problem in a multitude of different scenarios. We conclude that delay tolerant networking is an effective solution to the challenges created when dealing with sleep states while minimising overheads. However, current standardised delay tolerant technologies are not easily applicable for use with sensor networks, so a new standard needs to be created to meet the requirements described in the paper
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
Smart textile with integrated functional electrical stimulation and movement sensor for hand exercise
No full textStroke is the leading cause of adult movement disability, affecting 1.3 million people in the UK and 101 million people worldwide. Two thirds of stroke survivors have a weak upper limb affecting their independence and quali-ty of life. This work presents the user needs in stroke rehabilitation identified through focus group studies and 1:1 interviews. To address the usability issue of Functional Electrical Stimulation (FES) products used in stroke rehabilitation, we have developed a smart textile based electrode sleeve that allows users to use the FES device independently. Different textile materials (cotton, wool, Lycra) have been used in knitting a textile to achieve user comfort and the elasticity required to hold the electrodes in place. A sleeve assembly method has been developed to allow one-hand donning/doffing. Hand extension has been achieved by using a two-electrode FES system. The wrist bending angle was measured using two inertial measurement units (IMU). The bending angle and the user comfort achieved by the smart fabric electrodes and hydrogel electrodes are compared confirming that the fabric electrodes can be used to replace the hydrogel electrodes currently used in FES applications
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