Unidade de Investigação - CIIC - Computer Science and Communication Research Centre
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- High dynamic range - a gateway for predictive ancient lightingPublication . Gonçalves, Alexandrino José Marques; Magalhães, Luís; Moura, João; Chalmers, AlanIn the last few years, the number of projects involving historical reconstruction has increased significantly. Recent technologies have proven a powerful tool for a better understanding of our cultural heritage through which to attain a glimpse of the environments in which our ancestors lived. However, to accomplish such a purpose, these reconstructions should be presented to us as they may really have been perceived by a local inhabitant, according to the illumination and materials used back then and, equally important, the characteristics of the human visual system. The human visual system has a remarkable ability to adjust itself to almost all everyday scenarios. This is particularly evident in extreme lighting conditions, such as bright light or dark environments. However, a major portion of the visible spectra captured by our visual system cannot be represented in most display devices. High dynamic range imagery is a field of research which is developing techniques to correct such inaccuracies. This new viewing paradigm is perfectly suited for archaeological interpretation, since its high contrast and chromaticity can present us with an enhanced viewing experience, closer to what an inhabitant of that era may have seen. In this article we present a case study of the reconstruction of a Roman site. We generate high dynamic range images of mosaics and frescoes from one of the most impressive monuments in the ruins of Conimbriga, Portugal, an ancient city of the Roman Empire. To achieve the requisite level of precision, in addition to having a precise geometric 3D model, it is crucial to integrate in the virtual simulation authentic physical data of the light used in the period under consideration. Therefore, in order to create a realistic physical-based environment, we use in our lighting simulations real data obtained from simulated Roman luminaries of that time.
- IntelligentCart: Architecture of an Innovative System for the Acquisition of Products in Grocery StoresPublication . Santos, Diana S.S.; Pereira, António; Gonçalves, RamiroLarge grocery stores are nowadays used by millions of people for the acquisition of an enlarging number of products. Product acquisition represents a complex process that comprises time spent in corridors, product location and checkout queues. On the other hand, it is becoming increasingly difficult for retailers to keep their clients loyal and to predict their needs due to the influence of competition and the lack of tools that discriminate consumption patterns. In this article it is presented the proposal of an architecture and solution of an innovative system for the acquisition of products in grocery stores (IntelligentCart). The IntelligentCart explores emerging mobile technologies and automatic identification technologies (such as RFID) as a way to improve the quality of services provided by retailers and to augment the consumer value thus allowing to save time and money.
- Elder Care Modular SolutionPublication . Marcelino, Isabel; Pereira, António Manuel de JesusThe Elder Care solution has two primary goals: monitoring vital signs, sending alerts to family and specialized help and provide a social network in order to wrap all older population to avoid social isolation [1][2]. In this paper we will show the methodology used to obtain Elder Care's architecture and point some guidelines to our present work: Elder Care's implementation.
- Wireless Networks Interoperability - Wifi Wimax HandoverPublication . Silva, Hugues Mickael Carreira da; Figueiredo, Luís Filipe Calado Carvalho de; Rabadão, Carlos; Pereira, AntónioThe mobility with quality of service in wireless networks is a reality ever closer. The need for mobility while communicating becomes more and more necessary. Technologies for wireless networks with interoperability develops the concept of "communications anytime anywhere". Interoperability uses the handover to ensure the mobility of a mobile terminal through various communication infrastructures, supported by different technologies of wireless networks. Maintain the connection between base stations and mobile terminal is the key of the customer's satisfaction, with the guarantee of continuity of services and applications running, moving between different cells, using the technology of wireless communications to provide better coverage in the position where is. The aim of this study is to examine how the mobility between different access technologies in wireless networks can be optimized and what their behavior in scenarios of interoperability. To examine the quality of the service of mobility, we analyze the time required for the handover and the existing loss of packages, the latter being a very important factor to satisfy the user.
- 802.21-MPA-IMS ArchitecturePublication . Rodrigues, Carlos Miguel de Jesus; Rabadão, Carlos; Pereira, AntónioMobility has become a keyword nowadays with the evolution of mobile devices market and proliferation of realtime services. IP Multimedia Subsystem (IMS) is a single, standardized service framework that supports voice, video, data and messaging services, but does not provide seamless mobility for packet based sessions. This paper purposes an IMS architecture with IEEE 802.21 and media-independent pre-authentication (MPA) integrated. IEEE 802.21 can enable this seamless mobility in IMS and, additionally, MPA provides a secure handover optimization scheme, reducing, as a consequence, handover latency. The main goal of this architecture is to provide seamless and secure handovers between different access technologies in an IMS-based environment.
- Solving the weighted ring edge-loading problem without demand splitting using a Hybrid Differential Evolution AlgorithmPublication . Bernardino, Anabela; Bernardino, Eugénia; Sanchez-Perez, Juan Manuel; Gomez-Pulido, Juan Antonio; Vega-Rodriguez, Miguel AngelIn the last few years we have seen a significant growth in Synchronous Optical Network (SONET) deployments in telecommunication service providers. With growth of data traffic, network operators seek network-engineering tools to extract the maximum benefits out of the existing infrastructure. This has suggested a number of new optimization problems, most of them in the field of combinatorial optimization. We address here the Weighted Ring Edge-Loading Problem (WRELP). The WRELP is an important optimization problem arising in a popular ring topology for communication networks - given a set of nodes connected along a bi-directional SONET ring, the objective is to minimize the maximum load on the edges (pairwise) of a ring. Our procedure includes some original features, including the application of Hybrid Differential Evolution. We also perform comparisons with standard Differential Evolution, Genetic Algorithm and Tabu Search.
- A Practical Solution for Automatic Service Discovery and Usage over Resource Poor Ad-hoc Sensor NetworksPublication . Costa, Nuno; Pereira, António; Serôdio, CarlosAd-hoc networks present new challenges due to its mobility, lack of infrastructure and resource limited devices. This means that service discovery (and usage) protocols targeted for traditional networks are not suitable for ad-hoc networks because they usually rely on the fixed and high availability characteristics of nodes to run important services. Ad-hoc networks need service discovery protocols compliant with its mobility and changing topology. In this paper we present a practical solution capable of provide automatic service discovery and usage over ad-hoc networks of resource poor sensor nodes. The solution was not developed from the ground-up. Instead, it was based on a (successfully) solution for traditional networks but then modified to address ad-hoc networks while keeping it original semantics.
- Integration of Resource Poor Wireless Sensor Networks into Smart SpacesPublication . Costa, Nuno; Pereira, António; Serôdio, CarlosWireless Sensor networks (WSNs) have been referred to as one part of the background infrastructure required to achieve ubiquitous computing, where smart spaces are included. For instance, WSNs could be especially useful to compute the user context or even 'context' of mobile resources in general. To serve this purpose, wireless sensor network must expose some sort of service discovery and usage capability and be compatible with the nowadays ubiquitous technologies. In this paper we present a practical approach to bring WSNs, specially the ones built from resource poor sensor nodes, to participate into smart environments as ubiquitous devices. The approach addresses device heterogeneity, uses the state of the art and ubiquitous TCP/IP communication stack, is service driven and do not rely in any external resource rich device. As a result, we successfully created a Java based service discovery and usage protocol that is compliant with ad-hoc networks and resource constrained devices and a framework capable of produce the source and binary code ready to run on both resource constrained sensor nodes and PCs.
- Solving a Realistic Location Area Problem Using SUMATRA Networks with the Scatter Search AlgorithmPublication . Luz, Sónia Maria Almeida da; Vega-Rodríguez, Miguel A.; Gómez-Pulido, Juan A.; Sánchez-Pérez, Juan M.This paper presents a new approach based on the Scatter Search (SS) algorithm applied to the Location Management problem using the Location Area (LA) scheme. The LA scheme is used to achieve the best configuration of the network partitioning, into groups of cells (location areas), that minimizes the costs involved. In this work we execute five distinct experiments with the aim of setting the best values for the Scatter Search parameters, using test networks generated with realistic data [1]. We also want to compare the results obtained by this new approach with those achieved through classical strategies, other algorithms from our previous work and also by other authors. The simulation results show that this SS based approach is very encouraging.
- A Java Software Stack for Resource Poor Sensor Nodes: Towards Peer-to-Peer JiniPublication . Costa, Nuno; Pereira, António; Serôdio, CarlosSensor networks have been referred to as part of the background infrastructure required to achieve ubiquitous computing. This has recently promoted a considerable amount of attention from the research community that concluded that existing protocols and techniques for service discovery, such as JINI or UPnP are not suitable for the case of resource poor, battery-powered sensor nodes. We do not really agree with this approach. We think that those protocols could be a good starting point to "power-up" sensor nodes with poor resources for ubiquitous computing support. Starting from this principle and recognizing that existing sensor node system software is not suitable for our purpose, we decided to build a new sensor node software stack. The result was a stand-alone Java Virtual Machine, suitable for sensor nodes with poor resources, an implementation of the ubiquitous TCP/IP communication stack and Jini based middleware to achieve automatic service discover and usage. This software stack was tailored to perfectly fit in the state-of-the-art Mica2 class of sensor nodes.