Real-time WiFi localization of heterogeneous robot teams using an online random forest

In this paper we present a WiFi-based solution to the localization and mapping problem for teams of heterogeneous robots operating in unknown environments. By exploiting wireless signal strengths broadcast from access points, a robot with a large sensor payload creates a WiFi signal map that can then be shared and utilized for localization by sensor-deprived robots. In our approach, WiFi localization is cast as a classification problem. An online clustering algorithm processes incoming WiFi signals that are then incorporated into an online random forest (ORF). The algorithm’s robustness is increased by a Monte Carlo localization algorithm whose sensor model exploits the results of the ORF classification. The proposed algorithm is shown to run in real-time, allowing the robots to operate in completely unknown environments, where a priori information such as a blue-print or the access points’ location is unavailable. A comprehensive set of experiments not only compares our approach with other algorithms, but also validates the results across different scenarios covering both indoor and outdoor environments

IPv6 Multicast Forwarding in RPL-Based Wireless Sensor Networks

This article was published in the journal, Wireless Personal Communications [© Springer Science+Business Media] and the definitive version is available at: http://dx.doi.org/10.1007/s11277-013-1250-5In wireless sensor deployments, network layer multicast can be used to improve the bandwidth and energy efficiency for a variety of applications, such as service discovery or network management. However, despite efforts to adopt IPv6 in networks of constrained devices, multicast has been somewhat overlooked. The Multicast Forwarding Using Trickle (Trickle Multicast) internet draft is one of the most noteworthy efforts. The specification of the IPv6 routing protocol for low power and lossy networks (RPL) also attempts to address the area but leaves many questions unanswered. In this paper we highlight our concerns about both these approaches. Subsequently, we present our alternative mechanism, called stateless multicast RPL forwarding algorithm (SMRF), which addresses the aforementioned drawbacks. Having extended the TCP/IP engine of the Contiki embedded operating system to support both trickle multicast (TM) and SMRF, we present an in-depth comparison, backed by simulated evaluation as well as by experiments conducted on a multi-hop hardware testbed. Results demonstrate that SMRF achieves significant delay and energy efficiency improvements at the cost of a small increase in packet loss. The outcome of our hardware experiments show that simulation results were realistic. Lastly, we evaluate both algorithms in terms of code size and memory requirements, highlighting SMRF's low implementation complexity. Both implementations have been made available to the community for adoption

Evaluation of young smokers and non-smokers with Electrogustometry and Contact Endoscopy

<p>Abstract</p> <p>Background</p> <p>Smoking is the cause of inducing changes in taste functionality under conditions of chronic exposure. The objective of this study was to evaluate taste sensitivity in young smokers and non-smokers and identify any differences in the shape, density and vascularisation of the fungiform papillae (fPap) of their tongue.</p> <p>Methods</p> <p>Sixty-two male subjects who served in the Greek military forces were randomly chosen for this study. Thirty-four were non-smokers and 28 smokers. Smokers were chosen on the basis of their habit to hold the cigarette at the centre of their lips. Taste thresholds were measured with Electrogustometry (EGM). The morphology and density of the fungiform papillae (fPap) at the tip of the tongue were examined with Contact Endoscopy (CE).</p> <p>Results</p> <p>There was found statistically important difference (<it>p </it>< 0.05) between the taste thresholds of the two groups although not all smokers presented with elevated taste thresholds: Six of them (21%) had taste thresholds similar to those of non-smokers. Differences concerning the shape and the vessels of the fungiform papillae between the groups were also detected. Fewer and flatter fPap were found in 22 smokers (79%).</p> <p>Conclusion</p> <p>The majority of smokers shown elevated taste thresholds in comparison to non-smokers. Smoking is an important factor which can lead to decreased taste sensitivity. The combination of methods, such as EGM and CE, can provide useful information about the vascularisation of taste buds and their functional ability.</p

Efficient online WiFi delivery of layered-coding media using inter-layer network coding

A primary challenge in multicasting video in a wireless LAN to multiple clients is to deal with the client diversity - clients may have different channel characteristics and hence receive different numbers of transmissions from the AP. A promising approach to overcome this problem is to combine multi-resolution (layered) video coding with interlayer network coding. The fundamental challenge in such an approach is to determine the strategy of coding the packets across different layers that maximizes the number of decoded layers at all clients. This paper makes three contributions. (1) We first show that even for one client, the previously proposed canonical triangular scheme for inter-layer network coding can perform poorly. We show how to enhance the triangular scheme by incorporating the estimated target number of layers which significantly improves its effectiveness. (2) We show that such an enhanced triangular scheme still performs poorly for multiple clients with diverse channel characteristics, which motivates the need for searching for the optimal coding strategy. The naive way of searching for the optimal strategy is computationally prohibitive. We present several optimizations that drastically reduce the complexity of exhaustively searching for the optimal strategy, making it feasible in real time. (3) Finally, we design and evaluate an online video delivery scheme, Percy, to be deployed at a proxy behind the AP of a wireless LAN. Our simulation results show that Percy outperforms the previous inter-layer coding heuristic by up to 22-80% with varying numbers of clients. 2011 IEEE.Qatar National Research FundScopu

Altersbedingte elektrogustometrische Schwellenwerte sowie Gestalt und Gefäßversorgung der Papillae fungiformis

Einleitung: Auch für das Schmeckvermögen zeigt sich analog zu den übrigen Sinnessystemen ein altersabhängiger Funktionsverlust. Materialien und Methoden: Die Studie wurde an gesunden Nichtrauchern im Alter von 10 bis 70 Jahren durchgeführt(n=156, 74 m/82 w). Die Probanden wurden in 8 Altergruppen unterteilt (10-14, 15-19, 20-29, 30-39, 40-49, 50-59, 60-69 und >=69 Jahre). Es erfolgte eine elektrogustometrische Schwellenbestimmung sowie die Erfassung der Morphologie und Dichte der fungiformen Papillen (fPap) an der Zungenspitze mittels Kontaktendoskopie (KE).Ergebnisse: Die Schwellenwerte erhöhten sich ab einem Alter von 60 Jahren signifikant. Im Geschlechtervergleich konnten lediglich für weibliche Probanden zwischen 10-15 (p=0,043) und 20-29 Jahren (p=0,048) niedrigere Schwellenwerte bestimmt werden. In der der Chorda tympani zugeordneten Region lagen die Schwellenwerte bei den Probanden über 60 Jahren signifikant höher. Am Weichgaumen zeigten sich die Schwellwerte bei Männern mit 20-29 Jahren und über 60 Jahren erhöht gegenüber den jungeren (<19 Jahre) und Männern mit 30-59 Jahren. Bei Frauen über als 50 J. zeigten sich deutlich höhere Schwellenwerte als bei jüngeren Frauen.Dichteveränderungen anhand der KE konnten nur bei Männern über 50 bzw. und bei Frauen über 60 Jahren beobachtet werden. Die Gestalt und Gefäßverteilung der FP verschlechterte sich bei Leuten erhöhten Alters verschlechtern. Schlussfolgerung: Die vorliegende Arbeit stellt erstmals Alters-bedingte Veränderungen der elektrogustometrischen Schwellenwerte in einer europäischen (griechischen) Bevölkerung dar.Die kombinierte Verwendung von Elektrogustometrie und KE kann wertvolle Daten zur Untersuchung der Geschmacksfunktion liefern