ESTG - Comunicações em conferências e congressos internacionais
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- Discrete Compound Tests and Dorfman’s Methodology in the Presence of MisclassificationPublication . Santos, Rui; Martins, João Paulo; Felgueiras, MiguelCompound tests can be used to save resources for classification or estimation purposes in clinical trials and quality control. Nevertheless, the methodologies that are usually applied are restricted to qualitative group tests. Moreover, when quantitative compound tests are applied the problem is to ascertain whether the amount of some substance of any individual in the group is greater or lower than a prefixed threshold. An overview of the applications of the discrete compound tests highlights the advantages (to save resources) and disadvantages (higher probability of misclassification), and suggests criteria to assess the suitability of applying Dorfman’s methodology.
- Evaluation of seismic vulnerability assessment parameters for Portuguese vernacular constructions with nonlinear numerical analysisPublication . Ortega, Javier; Vasconcelos, Graça; Correia, Mariana; Rodrigues, Hugo; Lourenço, Paulo B.; Varum, HumbertoConsidering that vernacular architecture may bear important lessons on hazard mitigation and that well-constructed examples showing traditional seismic resistant features can present far less vulnerability than expected, this study aims at understanding the resisting mechanisms and seismic behavior of vernacular buildings through detailed finite element modeling and nonlinear static (pushover) analysis. This paper focuses specifically on a type of vernacular rammed earth constructions found in the Portuguese region of Alentejo. Several rammed earth constructions found in the region were selected and studied in terms of dimensions, architectural layout, structural solutions, construction materials and detailing and, as a result, a reference model was built, which intends to be a simplified representative example of these constructions, gathering the most common characteristics. Different parameters that may affect the seismic response of this type of vernacular constructions have been identified and a numerical parametric study was defined aiming at evaluating and quantifying their influence in the seismic behavior of this type of vernacular buildings. This paper is part of an ongoing research which includes the development of a simplified methodology for assessing the seismic vulnerability of vernacular buildings, based on vulnerability index evaluation methods.
- Hybrid channel-object approach for cinema post-production using particle systemsPublication . Fonseca, Nuno; Fonseca, NunoParticle systems are a new sound design approach that is receiving some attention from the cinema community due to the ability to handle thousands of sound sources simultaneously. Unfortunately, current immersive object-based audio formats are not prepared for such scale, forcing sound designers to use traditional channel-based audio approaches. This paper presents a hybrid approach that tries to merge the advantages of both object-based audio and channel-based audio. By using audio-objects with static positions, a high number of virtual "speaker channels" can be created, adding more space resolution than traditional channel-based formats, and allowing the mix of thousands of sounds. The proposed method can be used not only with particle systems software, but also on object-based audio down-mixing processes or even in high-demanding audio post-production workflows.
- Quality model for monitoring QoE in VoIP servicesPublication . Neves, Filipe; Cardeal, Simão; Soares, Salviano; Assunção, Pedro; Tavares, FilipeThis paper presents a no-reference model for monitoring the voice quality experienced by users in VoIP services. The proposed model is based on the E-Model, which is adapted from Recommendation ITU-T G.107 for this purpose. A calibration function was determined for relevant codecs under different packet loss conditions. Extensive field testing was carried out to validate the proposed model at PT Inovação Labs (Portugal). The results show that the mean opinion score (MOS) obtained from the proposed model match class C2 of conformance tests defined in ITU-T Recommendation P.564. The QoE model described in this paper was implemented in a VoIP QoE probe and is currently fully operational at Portugal Telecom.
- Enhanced H.264/AVC video streaming using network-adaptive multiple description codingPublication . Correia, P.; Assunção, P.; Silva, V.This paper presents a network-adaptive multiple description coding (MDC) method for enhanced video streaming over multipath channels. The novel feature of the proposed MDC network adaptation scheme is the generation of a controlled amount of side information to compensate for drift distortion due to packet loss. This yields higher robustness of multiple description (MD) H.264/AVC streams than single description (SD) ones. Multiple Description Scalar Quantisation (MDSQ) is used to split an SD video stream in two complementary streams (two descriptions) for transmission over a multipath channel. The simulation results show that significantly better quality is achieved by using the proposed scheme instead of either SDC streams or classic SDC-MDSQ network adaptation without side information.
- Modelling and measurements of the directional spectra of scatter signals inside a formation of tree trunksPublication . Leonor, N.; Caldeirinha, R.; Fernandes, T.; Ferreira, D.This article proposes a method to predict the scattered signal inside and around a tree trunk formation. The method presented here is based on an empirical model that characterises the re-radiation patterns of both dielectric and metallic cylinders for three spot frequencies, 9.4, 18.8 and 37.6 GHz and, resorting to dRET (discrete Radiative Energy Transfer) model to gather all the interaction between trunks within a formation, the received signal can be predicted. Presented empirical model was developed based on both dielectric and metallic re-radiation pattern measurements in an anechoic chamber and it is used as an input parameter of dRET model, characterising the trunk cells. This paper also contemplates measurements within a tree trunk formation in order to assess the values extracted from dRET model.
- Experimental Measurement of the Ne+ and Ne+2 Mobilities in Ne and the Reaction Rate Coefficient for Ne++2Ne→Ne+2+NePublication . Neves, P.N.B.; Garcia, A. N. C.; Trindade, A. M. F.; Barata, J. A. S.; Távora, L. M. N.; Conde, C. A. N.We measured the reduced mobilities of the atomic, Ne+, and dimer, Ne2+, ions in Ne, under different pressures and reduced electric fields, at 300 K. Extrapolation to zero field yields values of 4.4 cm2 V-1 s-1 for Ne+ and 6.2 cm2 V-1 s-1 for Ne2+, which are in relative good agreement with other published data. The Ne+ ions are converted to Ne2+ by a three-body reaction with a rate constant that was also measured. Its average value for reduced electric fields in the 8 to 12 Td range was (5.6 ± 0.1) × 10-32 cm6 s-1 at 300 K, also agreeing with the results from other authors using other techniques.
- @Sensor - Mobile application to monitor a WSNPublication . Moreira, Nuno; Venda, Marco; Silva, Catarina; Marcelino, Luis; Pereira, AntónioDue to the growth of potential of Wireless Sensor Networks (WSN), now becomes possible to use this technology in various new generation services such as monitor environment characteristics like temperature, humidity, among others. WSNs are emerging as a new paradigm, gathering information in a collaborative way, where independent sensor nodes collect and share information. In the last few years ubiquitous computing popularity has grown considerably, ambient intelligence and home automation systems are having a good public acceptance. In this context, we developed a mobile application to remotely monitor one WSN, installed at a customer's home. The application's main goal is to interact with a WSN, allowing a user to consult sensor states and receive sensor alerts. Sensor alerts will be received, in case a sensor's threshold value, exceeds the limit. Therefore the user will be notified whenever there are changes in the WSN. Apart the WSN, a base station is also needed for keeping the state of the WSN, store sensor's information and enable communication between the WSN and the developed mobile application via Web Services. This way and having a network connection, the user can check the state of any WSN component, anytime, anywhere. The Android platform was chosen to implement our application, since it is having a great acceptance and continued growth in the mobile market.
- Augmented reality system for inventoryingPublication . Real, João; Marcelino, LuísThis article presents and describes the implementation of an augmented reality system to assist in the task of warehouse inventory. The proposed system integrates an augmented reality engine (NyARToolkitCS) with a QR Code library. This integration enables users to capture product codes add the product's information to the view of the product itself. This article also presents the challenges for developing this system, the adopted architecture and the tested threshold algorithms. These algorithms were evaluated under real environment conditions.
- Next Generation Smart Home Systems Using Hardware Acceleration TechniquesPublication . Fuschelberger, David; Pyrounakis, Ioannis; Dagiuklas, Tasos; Voros, Nikolaos S.; Ribeiro, Carlos; Ribeiro, CarlosThis paper presents a proof-of-concept for home automation allowing capture, process and transmission of voice commands over Ethernet. The described approach relies on reconfigurable hardware and a software application for controlling distributed devices via vocal commands. An initial overall system evaluation was carried out to assess the system's performance. The solution has been deployed in a noisy environment simulating a typical scenario for the support of people with moving difficulties (e.g. Hospital room, retirement home living room). The attained results validate the worthiness of the concept. It is expected that this concept will evolve to a SoC (System-on-a-Chip) solution that could be easily deployed in real scenarios.