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Analysis and Implementation of New Techniques for the Enhancement of the Reliability and Delay of Haptic Communications
No full textHaptic communication is a science that recreates the feeling of touch or tactile sensation, which can be controlled by computer applications allowing interaction. The users receive feedback through different vibrations or forces in form of felt sensations in specific parts of the human body, such as hands. Typically used for games, haptic communications take advantage of vibrating joysticks or controllers to enhance on-screen activity, allowing the user to feel the outcome of having depressed a button. However, it can be also used in many other fields.
The most sophisticated touch technology is found in industrial, military and medical applications, where training people for tasks that require hand-eye coordination is needed. For instance, in surgery, medical students are able to master delicate surgical techniques using a computer, whilst feeling the real sensation of dealing with muscles, suturing blood vessels or injecting Botox into a virtual face or body. Besides, it is widely used in teleoperation, where a human controls the movement of a device or a robot and, at the same time, a homologous unit is recreating the motion in real time. Once these techniques have been mastered in a near future, the medical industry will benefit from virtual surgeries that provide a revolutionary concept for medical care. Furthermore, haptic technology shall establish emergent industries that had not been feasible for the time being.
In order to achieve the transmission of data in haptic communications, we need a master/slave model where a device had control over one or several devices. Also known as primary/secondary model, both parts have to be connected via network, and in this communication, we have to deal with different challenges such as delay, jitter or packet loss, which cause troublesome effects on the system. Additionally, we have to consider that the error rate of the packet shall be increased by fading in wireless communications. In order to overcome these harsh effects, error correcting technologies are used, and, specifically in this thesis, some Forward Error Correction (FEC) techniques have been applied, such as BCH or LDPC codes. Moreover, multipath diversity methods will be used for the purpose of the enhancement of delay and reliability. In terms of delay, some techniques will have to be dismissed since they make impossible a real-time communication despite they exhibit good behavior against errors.
This thesis mainly focuses on studying, proposing and implementing new approaches of transmittin
Effects of handoff algorithms on the performance of multimedia wireless networks
Get PDFAbstractHandoff is the procedure providing the connection to the backbone network while a mobile terminal is moving across the boundaries of coverage of two wireless points of connection. The complexity of the handoff decision process has led to the examination of a number of traditional and pattern recognition handoff decision algorithms for wireless networks. Traditional algorithms use a received signal strength measurement and an optional threshold, hysteresis, or a dwell timer to determine the handoff decision. Degradation of the signal level, however, is a random process, and simple decision mechanisms result in a ping–pong effect whereby several consecutive handoffs degrade the service provided by the network. Consequently, more complex pattern recognition algorithms are needed to decide on the optimal time for handoff. In these algorithms, the handoff decision receives off line training to create a reference database of possible handoff locations in an environment with an associated handoff "fingerprint" at those locations. This dissertation introduces newly designed neural network and adaptive network based fuzzy inference system (ANFIS) pattern recognition algorithms. To select appropriate algorithms for a specific wireless network, we need to create an analytical framework for performance evaluation. The design of a framework for comparative performance evaluation of different handoff algorithms is a complex problem as different networks have different performance evaluation criteria.This dissertation divides wireless networks into three categories according to their topology and wireless service application: traditional cellular phone networks, heterogeneous wireless data networks, and rate adaptive wireless data networks. For each category of wireless networks we define a performance evaluation scenario and using Monte Carlo simulations, Monte Carlo calculations, and direct mathematical analysis we analyze the effects of different handoff decision algorithms. The Manhattan micro-cellular scenario is used for traditional cellular phone networks. Using Monte Carlo simulations on this scenario, the performance of traditional and our neural network and ANFIS handoff decision algorithms are compared. A moving-in moving-out performance evaluation scenario for heterogeneous wireless data networks is defined to characterize intertechnology roaming between two networks with substantially different data rates. We use Monte Carlo calculations to define the optimum handoff location for a mobile terminal in this scenario. Using Monte Carlo simulations and the optimal handoff location, we perform comparative performance evaluation of newly introduced asymmetric traditional and pattern recognition algorithms designed for intertechnology handoff. Finally, we introduce two performance evaluation scenarios for rate adaptive wireless networks to characterize user mobility in rate adaptive networks with random and grid deployments. For the first scenario we provide mathematical analysis for the effects of handoff using relative power to calculate the average throughput observed by the mobile terminal for different distances between the two wireless points of connection. For the second scenario designed for grid deployment we present a comparative performance analysis using Monte Carlo calculations for four handoff decision algorithms.Academic dissertation to be presented, with the assent of the Faculty of Technology of the University of Oulu, for public defence in Raahensali (Auditorium L10), Linnanmaa, on June 26th, 2008, at 12 noonAbstract
Handoff is the procedure providing the connection to the backbone network while a mobile terminal is moving across the boundaries of coverage of two wireless points of connection. The complexity of the handoff decision process has led to the examination of a number of traditional and pattern recognition handoff decision algorithms for wireless networks. Traditional algorithms use a received signal strength measurement and an optional threshold, hysteresis, or a dwell timer to determine the handoff decision. Degradation of the signal level, however, is a random process, and simple decision mechanisms result in a ping–pong effect whereby several consecutive handoffs degrade the service provided by the network. Consequently, more complex pattern recognition algorithms are needed to decide on the optimal time for handoff. In these algorithms, the handoff decision receives off line training to create a reference database of possible handoff locations in an environment with an associated handoff "fingerprint" at those locations. This dissertation introduces newly designed neural network and adaptive network based fuzzy inference system (ANFIS) pattern recognition algorithms. To select appropriate algorithms for a specific wireless network, we need to create an analytical framework for performance evaluation. The design of a framework for comparative performance evaluation of different handoff algorithms is a complex problem as different networks have different performance evaluation criteria.
This dissertation divides wireless networks into three categories according to their topology and wireless service application: traditional cellular phone networks, heterogeneous wireless data networks, and rate adaptive wireless data networks. For each category of wireless networks we define a performance evaluation scenario and using Monte Carlo simulations, Monte Carlo calculations, and direct mathematical analysis we analyze the effects of different handoff decision algorithms. The Manhattan micro-cellular scenario is used for traditional cellular phone networks. Using Monte Carlo simulations on this scenario, the performance of traditional and our neural network and ANFIS handoff decision algorithms are compared. A moving-in moving-out performance evaluation scenario for heterogeneous wireless data networks is defined to characterize intertechnology roaming between two networks with substantially different data rates. We use Monte Carlo calculations to define the optimum handoff location for a mobile terminal in this scenario. Using Monte Carlo simulations and the optimal handoff location, we perform comparative performance evaluation of newly introduced asymmetric traditional and pattern recognition algorithms designed for intertechnology handoff. Finally, we introduce two performance evaluation scenarios for rate adaptive wireless networks to characterize user mobility in rate adaptive networks with random and grid deployments. For the first scenario we provide mathematical analysis for the effects of handoff using relative power to calculate the average throughput observed by the mobile terminal for different distances between the two wireless points of connection. For the second scenario designed for grid deployment we present a comparative performance analysis using Monte Carlo calculations for four handoff decision algorithms
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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