Nicolas D. Georganas
University of Ottawa
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Featured researches published by Nicolas D. Georganas.
IEEE Communications Surveys and Tutorials | 2007
Mojtaba Hosseini; Dewan Tanvir Ahmed; Shervin Shirmohammadi; Nicolas D. Georganas
In light of the slow deployment of IP Multicast technology on the global Internet and the explosive popularity of peer-to-peer (P2P) file-sharing applications, there has been a flurry of research activities investigating the feasibility of implementing multicasting capability at the application layer, referred to as Application Layer Multicasting (ALM), and numerous algorithms and protocols have been proposed. This article aims to provide researchers in the field with an understanding of ALM protocols by identifying significant characteristics, from both application requirements and networking points of view, and by using those characteristics as a basis for organizing the protocols into an integrated and well-structured format. Current trends and directions for further research are also presented. This article surveys the literature over the period 1995¿2005 on different application layer multicasting approaches.
Wireless Communications and Mobile Computing | 2003
Di Tian; Nicolas D. Georganas
In wireless sensor networks that consist of a large number of low-power, short-lived, unreliable sensors, one of the main design challenges is to obtain long system lifetime without sacrificing system original performances (sensing coverage and sensing reliability). In this paper, we propose a node-scheduling scheme, which can reduce system overall energy consumption, therefore increasing system lifetime, by identifying redundant nodes in respect of sensing coverage and then assigning them an off-duty operation mode that has lower energy consumption than the normal on-duty one. Our scheme aims to completely preserve original sensing coverage theoretically. Practically, sensing coverage degradation caused by location error, packet loss and node failure is very limited, not more than 1% as shown by our experimental results. In addition, the experimental results illustrate that certain redundancy is still guaranteed after node-scheduling, which we believe can provide enough sensing reliability in many applications. We implement the proposed scheme in NS-2 as an extension of the LEACH protocol and compare its energy consumption with the original LEACH. Simulation results exhibit noticeably longer system lifetime after introducing our scheme than before. Copyright
instrumentation and measurement technology conference | 2007
Qing Chen; Nicolas D. Georganas; Emil M. Petriu
This paper proposes a two level approach to solve the problem of real-time vision-based hand gesture classification. The lower level of the approach implements the posture recognition with Haar-like features and the AdaBoost learning algorithm. With this algorithm, real-time performance and high recognition accuracy can be obtained. The higher level implements the linguistic hand gesture recognition using a context-free grammar-based syntactic analysis. Given an input gesture, based on the extracted postures, the composite gestures can be parsed and recognized with a set of primitives and production rules.
IEEE Transactions on Instrumentation and Measurement | 2011
Nasser H. Dardas; Nicolas D. Georganas
This paper presents a novel and real-time system for interaction with an application or video game via hand gestures. Our system includes detecting and tracking bare hand in cluttered background using skin detection and hand posture contour comparison algorithm after face subtraction, recognizing hand gestures via bag-of-features and multiclass support vector machine (SVM) and building a grammar that generates gesture commands to control an application. In the training stage, after extracting the keypoints for every training image using the scale invariance feature transform (SIFT), a vector quantization technique will map keypoints from every training image into a unified dimensional histogram vector (bag-of-words) after K-means clustering. This histogram is treated as an input vector for a multiclass SVM to build the training classifier. In the testing stage, for every frame captured from a webcam, the hand is detected using our algorithm, then, the keypoints are extracted for every small image that contains the detected hand gesture only and fed into the cluster model to map them into a bag-of-words vector, which is finally fed into the multiclass SVM training classifier to recognize the hand gesture.
IEEE Instrumentation & Measurement Magazine | 2000
Emil M. Petriu; Nicolas D. Georganas; Dorina C. Petriu; Dimitrios Makrakis; Voicu Groza
Using the existing home infrastructure based on open industry standards, we will be able to integrate the home network with external networks to easily manage home devices, both locally and remotely. The advent of pervasive computing marks an urgent need for a new generation of intelligent sensing agents and information appliances. It will also demand environments for resource management of broad applications involving loosely coupled, event-driven, diverse information appliances. It is suggested that the development of intelligent sensing agents and sensor-based information appliances will spread pervasive technology to a multitude of human activities such as mining and manufacturing, security, transportation, sports, and health care. The topics discussed also include management of heterogeneous functions and networking technologies.
Journal of Lightwave Technology | 1991
Ganti N. M. Sudhakar; Nicolas D. Georganas; Mohsen Kavehrad
A number of cases of slotted Aloha protocols for high-speed optical fiber local area networks (LANs) are presented and analyzed. The results are compared to the cases of Slotted Aloha/Aloha schemes presented by I.M.I. Habab et al., (1987) and N. Mehravori (1990). The proposed schemes were found to offer better throughput and delay characteristics. These cases are also compared with Aloha/N-server and CSMA/N-server protocols presented by Habab and Mehravori. Some of the considered protocols offer better throughput when the data packet lengths are small. Two cases of reservation Aloha protocols are presented and analyzed. >
IEEE Transactions on Information Theory | 1998
Boris Tsybakov; Nicolas D. Georganas
This paper reviews and discusses the known definitions and properties of second-order self-similar discrete-time processes and supplements them with some more general conditions of self-similarity. A model for ATM cell traffic is presented and self-similarity conditions of this model are found. This study is motivated by observations that traffic in many real communication networks is self-similar in nature.
IEEE Transactions on Instrumentation and Measurement | 2008
Qing Chen; Nicolas D. Georganas; Emil M. Petriu
This paper proposes a new approach to solve the problem of real-time vision-based hand gesture recognition with the combination of statistical and syntactic analyses. The fundamental idea is to divide the recognition problem into two levels according to the hierarchical property of hand gestures. The lower level of the approach implements the posture detection with a statistical method based on Haar-like features and the AdaBoost learning algorithm. With this method, a group of hand postures can be detected in real time with high recognition accuracy. The higher level of the approach implements the hand gesture recognition using the syntactic analysis based on a stochastic context-free grammar. The postures that are detected by the lower level are converted into a sequence of terminal strings according to the grammar. Based on the probability that is associated with each production rule, given an input string, the corresponding gesture can be identified by looking for the production rule that has the highest probability of generating the input string.
wireless communications and networking conference | 2003
Di Tian; Nicolas D. Georganas
High delivery ratio with low energy consumption is one of design challenges for wireless sensor network routing protocols. In this paper, we identify the drawbacks of pure single path routing scheme and multipath routing scheme, in terms of guaranteed delivery with low energy consumption. Accordingly, we describe a scheme, in which data is forwarded along a pre-established single path to save energy, and a high delivery ratio is achieved by path repair whenever a break is detected. We propose a simple, quick, local path repairing approach, whereby a pivot node can skip over path break by only using the already existing routing information in its neighborhood. We implement this scheme and compare its performance with those of pure single path without repair and two multipath routing schemes. Simulation results show that in the same network topology with the same failed nodes, our single-path with repair routing scheme (SWR) has the highest delivery ratio among all the compared schemes in almost all the test cases. The energy consumed by SWR for one data delivery test is relatively low compared with the other schemes.
Computer Networks | 2001
Shervin Shirmohammadi; Nicolas D. Georganas
Abstract Synchronous collaboration in virtual reality spaces has specific requirements that differ from those of other application data, leading to a different communication approach. Update messages corresponding to the change in the state of a shared object must be communicated both reliably and in a timely manner among users. While a lot of research has been done in terms of transmission of update messages representing the motion of avatars and objects, very few works focus on collaboration itself. Here, we present an architecture that supports tightly coupled collaborative tasks to be performed efficiently in virtual environments. The architecture consists of an application-general layer which is mapped into a communication protocol. An implementation is also presented as proof of concept.