1,721,074 research outputs found
Effects of Emission from Different UWB Short-Range Communication Devices
No full textUltra-wideband (UWB) technology is a new concept in wireless short-range communication. It has numerous advantages that are resulted in producing different new products in various applications. This technology uses very short duration pulses hence occupies very large transmission bandwidth. This phenomenon may cause harmful interference in the existing wireless devices. The main objective of this study is to evaluate the effective parameters in ultra-wideband communication for indoor short-range devices. In this regard, two commercial UWB devices are utilized and effects of these devices in different experimental configurations are investigated. Three configurations including the effects of distance, narrowband spectrum, and another UWB device on bit error rate performance are evaluated. The results of the performed experiments showed the stability and amenability of the UWB technology to be used in multiple UWB devices
Effects of Emission from Different UWB Short-Range Communication Devices
Get PDFUltra-wideband (UWB) technology is a new concept in wireless short-range communication. It has numerous advantages that are resulted in producing different new products in various applications. This technology uses very short duration pulses hence occupies very large transmission bandwidth. This phenomenon may cause harmful interference in the existing wireless devices. The main objective of this study is to evaluate the effective parameters in ultra-wideband communication for indoor short-range devices. In this regard, two commercial UWB devices are utilized and effects of these devices in different experimental configurations are investigated. Three configurations including the effects of distance, narrowband spectrum, and another UWB device on bit error rate performance are evaluated. The results of the performed experiments showed the stability and amenability of the UWB technology to be used in multiple UWB devices
An Improved Active Network Concept and Architecture for Distributed and Dynamic Streaming Multimedia Environments with Heterogeneous Bandwidths
No full textA problem in todays Internet infrastructure may occur when a streaming multimedia application is to take place. The information content of video and audio signals that contain moving or changing scenes may simply be too great for Internet clients with low bandwidth capacity if no adaptation is performed. In order to satisfactorily reach clients with various bandwidth capacities some works such as receiver-driven multicast and resilient overlay networks (RON) have been developed. However these efforts mainly call for modification on router level management or place additional layer to the Internet structure, which is not recommended in the nearest future due to the highly acceptance level and widely utilization of the current Internet structure, and the lengthy and tiring standardization process for a new structure or modification to be accepted. We have developed an improved active network approach for distributed and dynamic streaming multimedia environment with heterogeneous bandwidth, such as the case of the Internet. Friendly active network system (FANS) is a sample of our approach. Adopting application level active network (ALAN) mechanism, FANS participants and available media are referred through its universal resource locator (url). The system intercepts traffic flowing from source to destination and performs media post-processing at an intermediate peer. The process is performed at the application level instead of at the router level, which was the original approach of active networks. FANS requires no changes in router level management and puts no additional requirement to the current Internet architecture and, hence, instantly applicable. In comparison with ALAN, FANS possesses two significant differences. From the system overview, ALAN requires three minimum elements: clients, servers, and dynamic proxy servers. FANS, on the other hand, unifies the functionalities of those three elements. Each of peers in FANS is a client, an intermediate peer, and a media server as well. Secondly, FANS members tracking system dynamically detects the existence of a newly joined computers or mobile device, given its url is available and announced. In ALAN, the servers and the middle nodes are priori known and, hence, static. The application level approach and better performance characteristics distinguished also our work with another similar work in this field, which uses router level approach. The approach offers, in general, the following improvements: FANS promotes QoS fairness, in which clients with lower bandwidth are accommodated and receive better quality of service FANS introduces a new algorithm to determine whether or not the involvement of intermediate peer(s) to perform media post-processing enhancement services is necessary. This mechanism is important and advantageous due to the fact that intermediate post-processing increases the delay and, therefore, should only be employed selectively. FANS considers the size of media data and the capacity of clients bandwidth as network parameters that determine the level of quality of service offered. By employing the above techniques, our experiments with the Internet emulator show that our approach improves the reliability of streaming media applications in such environment
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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
Automated eye blink detection and tracking using template matching
No full textEye blink detection is considered to be one of the most reliable sources of communication in modern human computer interaction (HCI) systems. This paper proposes a new method for eye blink detection using template matching and similarity measure. In order to minimize the false detection due to changing background in the video frame, face detection is applied before extraction of the eye template. Golden ratio concept is introduced for robust eye detection and is followed by eye template creation for tracking. Eye tracking is performed by template matching between template image and surrounding region. The normalized correlation coefficient is computed for successful eye tracking. Eye blink detection is performed based upon the correlation score as the score changes significantly whenever a blink occurs. The proposed system provides an overall precision of 92.8% and overall accuracy of 99.6% with 0.1% false positive rate in different experimental conditions.</p
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