Papers by Vassilios Kountouriotis
An RFID-based luggage and passenger tracking system for airport security control applications
Market analysis studies of recent years have shown a steady and significant increase in the usage... more Market analysis studies of recent years have shown a steady and significant increase in the usage of RFID technology. Key factors for this growth were the decreased costs of passive RFIDs and their improved performance compared to the other identification technologies. Besides the benefits of RFID technologies into the supply chains, warehousing, traditional inventory and asset management applications, RFID has proven itself worth exploiting on experimental, as well as on commercial level in other sectors, such as healthcare, transport and security. In security sector, airport security is one of the biggest challenges. Airports are extremely busy public places and thus prime targets for terrorism, with aircraft, passengers, crew and airport infrastructure all subject to terrorist attacks. Inside this labyrinth of security challenges, the long range detection capability of the UHF passive RFID technology can be turned into a very important tracking tool that may outperform all the limitations of the barcode tracking inside the current airport security control chain. The Integrated Systems Lab of NCSR Demokritos has developed an RFID based Luggage and Passenger tracking system within the TASS (FP7-SEC-2010-241905) EU research project. This paper describes application scenarios of the system categorized according to the structured nature of the environment, the system architecture and presents evaluation results extracted from measurements with a group of different massive production GEN2 UHF RFID tags that are widely available in the world market.
Boolean grammars extend context-free grammars by allowing conjunction and negation in rule bodies... more Boolean grammars extend context-free grammars by allowing conjunction and negation in rule bodies. This new formalism appears to be quite expressive and still efficient from a parsing point of view. Therefore, it seems reasonable to hope that boolean grammars can lead to more expressive tools that can facilitate the compilation process of modern programming languages. One important aspect concerning the theory of boolean grammars is their semantics. More specifically, the existence of negation makes it difficult to define a simple derivation-style semantics (such as for example in the case of context-free grammars). There have already been proposed a number of different semantic approaches in the literature. The purpose of this paper is to present the basic ideas behind each method and identify certain interesting problems that can be the object of further study in this area.
An agent-based crowd behaviour model for real time crowd behaviour simulation
Pattern Recognition Letters, 2014
ABSTRACT Crowd behaviour models are divided into agent-based, flow-based and particle-based in te... more ABSTRACT Crowd behaviour models are divided into agent-based, flow-based and particle-based in terms of whether the behaviour emerges from simulating all people (agents) individually (Koh and Zhou, 2011; Braun et al., 2005; Luo et al., 2008; Pan et al., 2007; Shendarkar et al., 2006; Narain et al., 2009), is programmatically defined a priori using fluid dynamics models (Hughes, 2002, 2003; He et al., 2011), or employ a particle system governed by physical laws (Helbing et al., 2000; Bouvier et al., 1997; Treuille et al., 2006; Cucker and Smale, 2007). In agent-based models, computationally intense problems, such as global navigation, hinder the efficient real-time modelling of thousands of agents. In this paper we present a novel approach to crowd behaviour modelling which couples the agent-based paradigm of allowing high level of individual parametrization (group behaviour between friends, leader/follower individuals) with an efficient approach to computationally intensive problems encountered in very large number of agents thus enabling the simulation of thousands of agents in real time using a simple desktop PC.
We deflne a higher-order extension of Datalog based on the Horn fragment of higher-order logic in... more We deflne a higher-order extension of Datalog based on the Horn fragment of higher-order logic introduced in (Wad91). Programs of Higher-Order Datalog can be understood declaratively as formulas in extensional higher-order logic, in which (for example) a unary predicate of unary predicates is a set of sets of data objects. The language retains all the basic principles of flrst-order logic programming. In particular, programs in this extended Datalog always have a minimum Herbrand model which can be computed in a bottom-up way. We present the syntax and semantics of our extended Datalog, state the main result cited above, and describe an implementation of this new language.
Theoretical Computer Science, 2011
We obtain a simple, purely game-theoretic characterization of Boolean grammars [A. Okhotin, Boole... more We obtain a simple, purely game-theoretic characterization of Boolean grammars [A. Okhotin, Boolean grammars, Information and Computation, 194 ]. In particular, we propose a two-player infinite game of perfect information for Boolean grammars, which is equivalent to their well-founded semantics. The game is directly applicable to the simpler classes of conjunctive and context-free grammars, and offers a promising new connection between game theory and formal languages.
Information and Computation, 2009
Boolean grammars [A. Okhotin, Information and Computation 194 (2004) are a promising extension of... more Boolean grammars [A. Okhotin, Information and Computation 194 (2004) are a promising extension of context-free grammars that supports conjunction and negation. In this paper we give a novel semantics for boolean grammars which applies to all such grammars, independently of their syntax. The key idea of our proposal comes from the area of negation in logic programming, and in particular from the so-called well-founded semantics which is widely accepted in this area to be the "correct" approach to negation. We show that for every boolean grammar there exists a distinguished (three-valued) language which is a model of the grammar and at the same time the least fixed point of an operator associated with the grammar. Every boolean grammar can be transformed into an equivalent (under the new semantics) grammar in normal form. Based on this normal form, we propose an O(n 3 ) algorithm for parsing that applies to any such normalized boolean grammar. In summary, the main contribution of this paper is to provide a semantics which applies to all boolean grammars while at the same time retaining the complexity of parsing associated with this type of grammars.
An RFID-based luggage and passenger tracking system for airport security control applications
Signal Processing, Sensor/Information Fusion, and Target Recognition XXIII, 2014
ABSTRACT Market analysis studies of recent years have shown a steady and significant increase in ... more ABSTRACT Market analysis studies of recent years have shown a steady and significant increase in the usage of RFID technology. Key factors for this growth were the decreased costs of passive RFIDs and their improved performance compared to the other identification technologies. Besides the benefits of RFID technologies into the supply chains, warehousing, traditional inventory and asset management applications, RFID has proven itself worth exploiting on experimental, as well as on commercial level in other sectors, such as healthcare, transport and security. In security sector, airport security is one of the biggest challenges. Airports are extremely busy public places and thus prime targets for terrorism, with aircraft, passengers, crew and airport infrastructure all subject to terrorist attacks. Inside this labyrinth of security challenges, the long range detection capability of the UHF passive RFID technology can be turned into a very important tracking tool that may outperform all the limitations of the barcode tracking inside the current airport security control chain. The Integrated Systems Lab of NCSR Demokritos has developed an RFID based Luggage and Passenger tracking system within the TASS (FP7-SEC-2010-241905) EU research project. This paper describes application scenarios of the system categorized according to the structured nature of the environment, the system architecture and presents evaluation results extracted from measurements with a group of different massive production GEN2 UHF RFID tags that are widely available in the world market.
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Papers by Vassilios Kountouriotis