Abstract
The extraction of relevant objects (foreground) from a background is an important first step in many applications. We propose a technique that tackles this problem using a cascade of change detection tests, including noise-induced, illumination variation and structural changes. An objective comparison of pixel-wise modelling methods is first presented. Given its best relation performance/complexity, the mixture of Gaussians was chosen to be used in the proposed method to detect structural changes. Experimental results show that the cascade technique consistently outperforms the commonly used mixture of Gaussians, without additional post-processing and without the expense of processing overheads. ©2007 IEEE.

Abstract
In this paper, we study the performance of the optimum receiver for nonlinear distorted OFDM signals in RoF applications, which is composed by a demodulator followed by an ML detector. The demodulator observes the various intermodulation products to compute a set of sufficient statistics, while the detector observes the sufficient statistics to compute an estimate of the original data. Particularly, we concentrate on the uplink of intensity modulation/direct detection RoF system where the OFDM signal suffers from linear distortion (fading), nonlinear distortion and noise. We demonstrate that the optimum receiver outperforms the conventional OFDM receiver by several orders of magnitude.

Abstract
This paper presents the design of a low-pass microwave filter based on the EBG (Electromagnetic Bandgap) concept. The structure is composed of a microstrip line in one of the layers and two different periodic superimposed EBG structures in the ground plane. The first structure defines the characteristics of the filter in the pass-band whereas the second periodic structure is used to reduce the second harmonic spurious response. The filter exhibits a flat pass-band response and a cut-off rate better than 380 dB/octave. © 2007 IEEE.

Abstract
Originally defined by the Third Generation Partnership Project (3GPP) as part of its standardization work for 3G mobile phone systems, the IMS model has been adopted as a baseline technology for network and service convergence by network (wireless, wireline and cable), service and content operators. Dealing with the same business actors, the ENTHRONE project (FP6-IP-507637) builds an MPEG-21-based service management system that enables distribution of audio-visual content with dynamic end-to-end QoS guarantees over heterogeneous networks to various types of terminal devices. This system controls the access of users to the content and supervises the delivery of the content to ensure the level of QoS. The paper examines how the IMS model could be extended to include service management features offered by the ENTHRONE management system. These features could constitute a potential vehicle for the IMS entrance to the audio-visual market chain. Copyright © 2007 John Wiley & Sons, Ltd.

Abstract
This paper proposes a framework for a virtual classroom application based on a Virtual Collaboration System (VCS), which is being developed under the VISNET II Network of Excellence (NoE)1, and discusses adaptation technologies that enable seamless access to classroom sessions while intellectual property and digital rights are managed. The proposed virtual classroom framework enables academic institutions to conduct their collaborative lecture series, to which registered students will be able to attend remotely and interactively over the Internet. Furthermore, the general public may also follow the classroom sessions under certain restrictions imposed by the participating institutions. In order to facilitate seamless access to a heterogeneous audience that is composed of users with various preferences and privileges accessing the classroom sessions over different network infrastructures and using terminal devices with diverse capabilities, context-aware content adaptation is required to meet constraints imposed by the usage context and enhance the quality of the user experience. Thus, this paper describes the concepts and functionalities of a context-aware content adaptation platform that suits the requirements of such multimedia application scenarios. This platform is able to consume low-level contextual information to infer higher-level contexts, and thus decide the need for and type of adaptation operations to be performed upon the content. In this way, it is aimed to meet usage constraints while also satisfying restrictions imposed by the Digital Rights Management (DRM) to govern the use of protected content.

Abstract
MPEG-21 enables content consumers to access and interoperate with a large variety of multimedia resources and their descriptions in a flexible manner. Considering the great heterogeneity that presently exists across the entire multimedia content chain and the growing importance of open standards to facilitate the interoperations across environments, applications and formats, an MPEG-21 Peer was developed to process and present complex multimedia content, represented as MPEG-21 Digital Items. The novelty of the work essentially relies on the adoption of a Web Services architecture, based on a single Digital Items processing core available for all types of terminal devices.