Abstract
In the context of the versatile link project, a set of semiconductor lasers were studied and modelled aiming at the optimization of the laser driver circuit. High frequency measurements of the laser diode devices in terms of reflected and transmission characteristics were made and used to support the development of a model that can be applied to study their input impedance characteristics and light modulation properties. Furthermore the interaction between the laser driver, interconnect network and the laser device itself can be studied using this model. Simulation results will be compared to measured data to validate the model and methodology.

Abstract
First generation of overlay P2P networks had scalability problems although offering useful keyword-base searching functionality. The new generation of structured networks, based on Distributed Hash Tables (DHT), solved the scalability problem but at the same time eliminated the possibility of performing searches by proximity. This can be considered as an effective limitation as users of P2P networks will most often not have the complete information about the data they are looking for. Accordingly they tend to submit general queries to the network, hoping to receive back a list of results that match their needs. In this paper we describe a solution that is able to profit from the best of the two approaches. It relies on a two-layer architecture, offering on the top layer a set of Web Services to upload, search and retrieve content and on the bottom layer a fully structured P2P network (DHT-based) for distribution and downloading efficiency. Central to our solution, is the use of distributed databases, implemented at the top layer, holding descriptive metadata of the uploaded digital objects. The developed system also makes use of the JXTA project at the top layer and the Bit Torrent suite of protocols at the bottom layer. © 2009 IADIS.

Abstract
Context-aware applications are fast becoming popular as a means of enriching users' experiences in various multimedia content access and delivery scenarios. Nevertheless, the definition, identification, and representation of contextual information are still open issues that need to be addressed. In this paper, we briefly present our work developed within the VISNET II Network of Excellence (NoE) project on context-based content adaptation in Virtual Collaboration Systems (VCSs). Based on the conducted research, we conclude that MPEG-21 Digital Item Adaptation (DIA) is the most complete standardization initiative to represent context for content adaptation. However, tools defined in MPEG-21 DIA Usage Environment Descriptors (UEDs) are not adequate for Virtual Collaboration application scenarios, and thus, we propose potential extensions to the available UEDs.

Abstract
The use of context is already a reality in different application fields. One such example is the Robotics field, where sensors are used to capture information about the surrounding environment, allowing the system to react to changes. But also in the multimedia cornmunications field, some work has recently emerged to allow combining sensed context and use that combined information to decide how to adapt the content. This paper describes the MULTICAO ontology, which lies at the core of an Adaptation Decision Engine, providing it with a formal description of the surrounding environment in a similar way as humans would describe it. This way the system has higher chances to take adaptation decisions that best meet users' expectations.

Abstract
Non-rectangular cores of standard-cell-based reconfigurable logic can be used to fill space left on System-on-Chips, thereby providing the system with hardware reconfigurability. The proposed architecture for a non-rectangular reconfigurable core is based on a fixed set of blocks that implement logic functions, interconnections and configurable switching. The basic blocks connect by abutment to form clusters and clusters abut to form a complete reconfigurable core. A software tool was created to generate a gate-level netlist and the floorplan data of the reconfigurable logic core together with a basic testbench. Cores with non-rectangular shapes were created using 90 nm and 45 nm standard-cell technologies and validated by simulation. The results demonstrate the feasibility of a flexible, technology-independent architecture for non-rectangular reconfigurable logic cores that can be physically implemented using a standard digital design flow.

Abstract
Human recognition of isolated vowels is quite robust considering intra and inter-speaker variability. Automatic recognition techniques typically exhibit poor performances, notably in the case of female or child speech because a higher fundamental frequency (F0) generates a sparser sampling of the magnitude spectrum. In this paper we extend previous results on a perceptually motivated concept of vowel recognition that is based on Perceptual Spectral Clusters (PSC) of harmonic partials. We study the effect of normalizing relevant PSC features by F0 taking as a reference the recognition performance of static features derived from either Linear Prediction (LP) analysis or Mel-Frequency Cepstral Coefficients (MFCC), and using the Mahalanobis distance on a data base of five natural Portuguese vowel sounds uttered by 44 speakers. Test results reveal that the recognition performance of F0-normalized PSC features increases approaching that of MFCC coefficients. These results are significant as PSC related features are amenable to concurrent vowel identification while LP or MFCC-related features are not.