ESTG - Comunicações em conferências e congressos internacionais
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Percorrer ESTG - Comunicações em conferências e congressos internacionais por Objetivos de Desenvolvimento Sustentável (ODS) "09:Indústria, Inovação e Infraestruturas"
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- 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.
- Accuracy versus complexity of MARG-based filters for remote control pointing devicesPublication . Rasteiro, Miguel ; Costelha, Hugo; Conde Bento, Luis; Assunção, PedroAlthough most current pointing devices rely on relative rotation increments, absolute orientation allows for a more intuitive interaction. However, this is difficult to implement in low-energy consumption devices since accurate fusion filters are computationally intensive. This work presents a comparative study of low-complexity filters and state-of-the-art orientation tracking systems, enabling to access complexity versus portability. A relevant set of different MARG units currently available on the market were studied under systematic tests and human subjective user analysis. Experimental results show that it is possible to obtain similar accuracy using low-complexity filters to the ones observed with state-of-the-art orientation tracking systems. © 2015 IEEE.
- Adjustment parameters of an internal combustion engine working with methanePublication . Dimitrov, R.; Bogdanov, K.; Wrobel, R.; Mihaylov, V.; Serrano, Luis; Institute of Physics PublishingThe paper presents a study of the variation of ignition advance when the engine works with methane and a comparison with values when the engine runs on gasoline. It is known that methane has a lower burning velocity than gasoline, and therefore, to obtain a maximal efficiency from the working process (the maximum value of cylinder pressure pz should be 7-15 degrees after TDC), ignition advance should be increased, as for different operating regimes this angle should be increased with different values. A gasoline engine has been studied and were measured and analysed the ignition advance at work with gasoline and methane, with optimal air-fuel ratio (α) for both fuels. Three-dimensional graphics of ignition advance variation across the rpm and load range were made. In conclusion, on the basis of the experiments, a table is produced, which presents the values of coefficients for change of base parameters of ignition advance for all engine operating modes, in dependence on rpm and load of the engine.
- Advances in thermoplastic pultruded compositesPublication . Novo, P.J.; Silva, J.F.; Marques, A.T.Pultrusion is a versatile continuous high speed production technology allowing the production of fibre reinforced complex profiles. Thermosetting resins are normally used as matrices in the production of structural constant cross section profiles. Although only recently thermoplastic matrices have been used in long and continuous fibre reinforced composites replacing with success thermosetting matrices, the number of their applications is increasing due to their better ecological and mechanical performance. Composites with thermoplastic matrices offers increased fracture toughness, higher impact tolerance, short processing cycle time and excellent environmental stability. They are recyclable, post-formable and can be joined by welding. The use of long/continuous fibre reinforced thermoplastic matrix composites involves, however, great technological and scientific challenges since thermoplastics present much higher viscosity than thermosettings, which makes much difficult and complex the impregnation of reinforcements and consolidation tasks. [1] In this work continuous fibres reinforced thermoplastic matrix towpregs were produced using equipment developed by the Institute for Polymers and Composites (IPC). The processing of the towpregs was made by pultrusion, in a developed prototype equipment existing in the Engineering School of the Polytechnic Institute of Porto (ISEP). Different thermoplastic matrices and fibres raw-materials were used in this study to manufacture pultruded composites for commercial applications (glass and carbon fibre/ polypropylene) and for advanced markets (carbon fibre/Primospire®). To improve the temperature distribution profile in heating die, different modifications were performed. In order to optimize both processes, towpregs production and pultruded composites profiles were analysed to determine the influence of the most relevant processing parameters in the final properties. The final pultruded composite profiles were submitted to mechanical tests to obtain the relevant properties
- Agile Accessibility Assessment: Development and Evaluation of Native SoftwarePublication . de Sousa e Silva, João; Pereira, António; Ferreira, Rui Bragança; Gonçalves, RamiroThe information and communication technologies (ICT) have the potential to improve the quality of life of individual with functional particularities, potentiating their activity in society, as well supplying the conditions for a prolonged active life, counter acting the natural age related lost of faculties. As such, the software component – of ICT – is lacking a good and attentive construction to these functioning details which, often, are of difficult assessment. Adding to these constrains, the existing information is, not exclusively but especially, focused on Web contents. Attending to these matters, a checklist of proposals has been elaborated, and presented in this paper, that tries to cover these flaws, allowing for an evaluation of the accessibility of Integrated Development Environments (IDE), their capacity of generating accessible software – native software and not Web contents -, and even the accessibility of the final product – the native software. Conceived through the reutilization and inspired on the general knowledge created by the Web Accessibility Initiative (WAI), the drafts of this checklist are easily understandable and applicable. With the objective of facilitating the work of information systems technician who may already have concerns regarding these topics, it further has the important potential of encouraging agents to initiate themselves into the cares that this are requires.
- Assessing the influence of uncertainty in land cover mapping and digital elevation models on flood risk mappingPublication . Gonçalves, Luísa M.S.; Fonte, Cidália C.; Gomes, RicardoThis paper proposes an approach to assess the influence of the uncertainty present in the parameters dependent on the land cover and elevation data over the peak flow values and the subsequent delineation of flooded areas. The proposed approach was applied to produce vulnerability and risk maps that integrate uncertainty for the urban area of Leiria, Portugal. A SPOT-4 satellite image and DEMs of the region were used. The peak flow was computed using the Soil Conservation Service method and HECHMS, HEC-RAS, Matlab and ArcGIS software programs were used. The analysis of the results obtained for the presented case study enables the identification of the order of magnitude of uncertainty associated to the watershed peak flow value and the identification of the areas which are more susceptible to flood risk to be identified.
- Automatic network configuration in virtualized environment using GNS3Publication . Emiliano, Rodrigo; Antunes, MárioComputer networking is a central topic in computer science courses curricula offered by higher education institutions. Network virtualization and simulation tools, like GNS3, allows students and practitioners to test real world networking configuration scenarios and to configure complex network scenarios by configuring virtualized equipments, such as routers and switches, through each one's virtual console. The configuration of advanced network topics in GNS3 requires that students have to apply basic and very repetitive IP configuration tasks in all network equipments. As the network topology grows, so does the amount of network equipments to be configured, which may lead to logical configuration errors. In this paper we propose an extension for GNS3 network virtualizer, to automatically generate a valid configuration of all the network equipments in a GNS3 scenario. Our implementation is able to automatically produce an initial IP and routing configuration of all the Cisco virtual equipments by using the GNS3 specification files. We tested this extension against a set of networked scenarios which proved the robustness, readiness and speedup of the overall configuration tasks. In a learning environment, this feature may save time for all networking practitioners, both beginners or advanced, who aim to configure and test network topologies, since it automatically produces a valid and operational configuration for all the equipments designed in a GNS3 environment.
- Children's reading aloud performance: a database and automatic detection of disfluenciesPublication . Proença, Jorge; Celorico, Dirce; Candeias, Sara; Lopes, Carla; Perdigão, FernandoThe automatic evaluation of children's reading performance by detecting and analyzing errors and disfluencies in speech is an important tool to build automatic reading tutors and to complement the current method of manual evaluations of overall reading ability in schools. A large amount of speech from children reading aloud plentiful in errors and disfluencies is needed to train acoustic, disfluency and pronunciation models for an automatic reading assessment system. This paper describes the acquisition and analysis of a read-aloud speech database of European Portuguese from children aged 6-10 from the first to fourth school grades. Towards the goal of detecting all reading errors and disfluencies, we apply a decoding process to the utterances using flexible word level lattices that allow syllable based false starts and repetitions of two or more word sequences. The proposed method proved promising in detecting corrections and repetitions in sentences, and provides an improved alignment of the data, helpful for future annotation tasks. The analysis of the database also shows agreement to government defined curricular goals for reading.
- Collaborative Vehicle Self-Localization Using Multi-GNSS Receivers and V2V/V2I CommunicationsPublication . Conde Bento, Luis; Chelim, Rafael; Nunes, UrbanoThis paper presents a collaborative self-localization approach using a multi-GNSS receiver setup and V2V/V2I communications. The purpose is to develop a low-cost alternative (equipment and installation), without compromising the process of localization estimation. The proposed method uses two GPS-receivers installed on the vehicle, disposed longitudinally on the cover (to maximize the distance among receivers) in order to estimate the Yaw and Pitch angles. To estimate the Roll angle, the proposed approach uses information from a receiver on the road infrastructure or on a nearby vehicle using V2V and/or V2I communication (compliant with 802.11p standard). Experimental results revealed that the performance on both absolute positioning and Pitch angle estimation is very high. The method is accurate in Yaw angle estimation enabling acceptable results in heading computation. Therefore the use of this algorithm in risk assessment on crossroads approaching scenarios, is achievable with an affordable setup. The Roll angle estimation can reach satisfactory results if there is a third receiver in the vicinity and in a non-collinear position with respect to the installed onboard receivers.
- Comparison by computer fluid dynamics of the drag force acting upon two helmets for wheelchair racersPublication . Forte, P; Marinho, D. A.; Morouço, P; Pascoal-Faria, P.; Barbosa, T. M.The aim of this study was to compare the drag force created by two helmets (time trial and road)used by a wheelchair racer. The head and helmet of the racer were scanned to obtain the3D models. Numerical simulation was run on Fluent, having as output the drag force for both helmets (road and time trial) in two different positions (0º and 90º) and increasing velocities (from 2.0 to 6.5 m/s). The greatest aerodynamic drag was noted wearing a time trial helmet in 90º ranging from 0.1025N to 0.8475N; this was also the position with the highest drag. The velocity with higher drag for booth helmets was at 6.5 m/s. The time trial helmet at 0º had the lower aerodynamic drag, compared with the same position of road helmet. The drag force seems to be lower wearing the time trial helmet and keeping the 0º position and, thus, should be considered for sprinting events.