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Petri Nets have proven useful as a language for expressing distributed control logic. This paper presents a tool that integrates the formalism with virtual reality technology in order to model functioning mechatronic systems in 3D. A virtual environment generates sensor telemetry and reflects the state of actuators by computing the geometric and physical properties of a system and the surrounding environment. Petri Nets, combined with the Python programming language, model control systems in terms of virtual sensors and actuators. This methodology simulates the interactions between the structure and logic of mechatronic systems, allowing for an early verification of designs. [ABSTRACT FROM AUTHOR]

In this paper, we present an overall architecture to integrate SIP-based session management with scalable QoS features and AAA functionality. The QoS features include a bandwidth reservation in the access network based on the Next Steps in Signaling (NSIS) architecture. Furthermore, we employ the DiffServ compliant Priority Promotion Scheme (PPS) which is a packet probing scheme to verify end-to-end premium bandwidth availability. To avoid misuse of the QoS features AAA functionality is added that binds the QoS usage with the specific SIP sessions. The AAA functionality is achieved by applying a combination of the widespread RADIUS protocol with the Common Open Policy Service (COPS). As a proof of concept our architecture has been implemented and performance tested. The strength of our approach is that it keeps away complexity from the carrier networks while providing QoS with access control in a scalable fashion. Keywords: SIP, QoS, AAA, real-time interactive services, bandwidth probing. [ABSTRACT FROM AUTHOR]

We present a short geometric proof for the price of anarchy results that have recently been established in a series of papers on selfish routing in multicommodity flow networks. This novel proof also facilitates two new types of results: On the one hand, we give pseudo-approximation results that depend on the class of allowable cost functions. On the other hand, we derive improved bounds on the inefficiency of Nash equilibria for situations in which the equilibrium travel times are within reasonable limits of the free-flow travel times. These tighter bounds help to explain empirical observations in vehicular traffic networks. Our analysis holds in the more general context of congestion games, which provides the framework in which we describe this work. [ABSTRACT FROM AUTHOR]