ESTG - Comunicações em conferências e congressos internacionais
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- Silent television: S_TVPublication . Silva, Emanuel; Maximiano, Filipa; Silva, Mateus; Ferreira, Rui; Rodrigues, NunoThis paper presents a solution that allows the users of a certain place to hear the sound of a TV, even if they are in a noisy environment. This gives the users a more efficient way to hear the sound of televisions in places where the volume of noise is high. The solution, named "s_TV" comprises two modules: the transmitter and the receiver. The transmitter module is composed by equipment to capture and transmit sound from the TV to smartphones/tablets Android. This equipment is connected to the TV and a router and transmits the sound through a network to Android devices. It can also transmit other types of information, such as the TV settings. An application was also developed to allow the configuration and handling of the servers that emit the sound of televisions. The receiver module resulted in a mobile application that allows the user to choose in a very simple and intuitive way, a particular TV channel and, subsequently, receive and play the sound on the mobile device, in real time. In addition, other features are available such as recording the sound played and sharing it on social networks. The tests conducted indicate that the solution may also be used in real-world scenarios with a scalable number of users, without compromising the services available on existing Wi-Fi networks.
- Thermal analysis of an extrusion system of a 3-D bioprinterPublication . Ribeiro G.S.; Silva J.V.L.; Freitas D.; Bartolo P.; Almeida, Henrique de Amorim; Silveira Z.C.This work presents a finite element thermal analysis of a 3-D bioprinter desktop based on Fused Deposition Modeling (FDM) with applications on tissue engineering, designed by the Centre for Rapid and Sustainable Product Development - Leiria, Portugal. The purpose of this work it is compare three possibilities of temperature control of the machine during the extrusion process, considering the use of a biodegradable polyester (Polycaprolactone - PCL) as raw material. The first two configurations simulate approaches typically adopted in an attempt to keep the polymer as close as possible to 80 °C and prevent its premature solidification at a critical point. The third configuration considers a hypothetical material substitution to enhance thermal conductivity. The results indicate that the first two configurations are not sufficient to achieve total control of the polymer temperature. However, the third configuration show a significant potential to improve the thermal control of the extrusion process.
- Development of a distributed electronic system for low-cost heavy-duty engine test benchPublication . Rodrigues Gouveia, Olivier; Borges, Alexandre; Costa, Diogo; Coelho, Diogo; Lopes, Paulo; Perpétua, Hugo; Serrano, Luis; Ferreira, CarlosTest benches are important tools for the optimization and diagnosis of internal combustion engines. This paper presents the work done to develop a low-cost tech bench for heavy-duty engines, which uses an electromagnetic brake, to apply load to the engine, and a distributed electronic system for control and data acquisition. Signal noise contamination in test benches represents a problematic aspect of the engine testing. Moreover, a distributed control and monitoring electronic systems, allied with a Controller Area Network (CAN) communication bus for signal transmission, was used to mitigate and ultimately immunize signals from noise sources such as electric or electromagnetic fields. Overall, a heavy-duty test bench aiming the engines diagnostics was obtained, where all control and data acquisition is performed via an USB serial port, interfacing with two CAN bus networks, in a complete distributed control system.
- A feasibility study on the extension of the point scatterer formulation to include wind induced dynamicsPublication . Leonor, N; Caldeirinha, Rafael; Sanchez, M; Fernandes, Telmo; Morgadinho, S.This paper presents a feasibility study on the extension of the point scatterer formulation to include time-varying effects caused by wind induced channel dynamics. This modeling approach, which is based on a ray-tracing algorithm, employs various point scatterers with specific radiation characteristics, distributed within a computational volume, to characterize the electromagnetic behavior in the presence of trees and vegetation volumes. This propagation model has now been extended to include the time-varying received signal level, caused by the swaying motion of branches, twigs and leafs. To this extent, a statistical model is used to characterize the time-varying attenuation of each multipath component. The performance of the proposed model is assessed against measurements intended to record the dynamic re-radiation pattern of a tree in various windy conditions, which included four wind directions and two wind speeds.
- Automatic Evaluation of Children Reading Aloud on Sentences and PseudowordsPublication . Proença, Jorge; Lopes, Carla; Tjalve, Michael; Stolcke, Andreas; Candeias, Sara; Perdigão, FernandoReading aloud performance in children is typically assessed by teachers on an individual basis, manually marking reading time and incorrectly read words. A computational tool that assists with recording reading tasks, automatically analyzing them and providing performance metrics could be a significant help. Towards that goal, this work presents an approach to automatically predicting the overall reading aloud ability of primary school children (6-10 years old), based on the reading of sentences and pseudowords. The opinions of primary school teachers were gathered as ground truth of performance, who provided 0-5 scores closely related to the expectations at the end of each grade. To predict these scores automatically, features based on reading speed and number of disfluencies were extracted, after an automatic disfluency detection. Various regression models were trained, with Gaussian process regression giving best results for automatic features. Feature selection from both sentence and pseudoword reading tasks gave the closest predictions, with a correlation of 0.944. Compared to the use of manual annotation with the best correlation being 0.952, automatic annotation was only 0.8% worse. Furthermore, the error rate of predicted scores relative to ground truth was found to be smaller than the deviation of evaluators’ opinion per child.
- Comparative Study of Computational Electromagnetics Applied to Radiowave Propagation in WildfiresPublication . Faria, Stefânia; Vala, Mário; Coimbra, Pedro; Felício, João; Leonor, Nuno; Fernandes, Carlos; Salema, Carlos; Caldeirinha, RafaelIn this paper, a comparative study of four computational electromagnetic techniques to model the 2-dimensional radiowave propagation phenomena in wildfires, is proposed. The fire dynamics for a small tree specimen is studied, in which gases released from the combustion process are used to investigate the generation of an ionised plasma and, thus, to evaluate the gradient of the medium refractive index using the cold plasma model. Consequently, the presence of fire has been demonstrated to introduce additional losses in the radio path that may be critical to radio communication systems that are widely used in mission critical applications. The gradient of the refractive index across the vegetation volume yielded by the cold plasma model is used as input parameter to different numerical methods and electromagnetic solvers at 385 MHz (i.e. TETRA frequency band in Portugal) and, subsequently, their applicability to wildfires is assessed.
- 3D Indoor Radio Coverage for 5G Planning: a Framework of Combining BIM with Ray-tracingPublication . Louro, João; Fernandes, Telmo Rui; Rodrigues, Hugo; Caldeirinha, Rafael F. S.This paper presents a framework to predict indoor radio wave coverage in buildings. Such method includes the capability to import BIM (Building Information Modelling) files that contain structured physical geometry and dimension data, including the material types that are of uttermost importance in evaluating their dielectric properties. Appropriated extraction of physical and dielectric attributes of the building elements was used as input to a 3D radio wave propagation ray-tracing developed in MatLab that allows the prediction of the received radio signal level at any location within the computational volume. Results are presented for line-of-sight contributions and first and second order reflections. Despite the generic nature of the proposed framework, prediction results are presented at 3.6 GHz, envisaging emerging 5G indoor radio coverage.
- Estimation of prevalence in rare disease using pooled samplesPublication . Martins, J. P.; Santos, R.; Felgueiras, M.The use of pooled samples for screening infected individuals is a known procedure to reduce costs. In an estimation problem, the aim is only to determine how many individuals are infected instead of determining who is infected (classification problem). In that setting, our goal was to compare the performance of using one or two-dimensional arrays. The best performance was established according to one of the following criteria: minimizing the number of individuals or the number of tests required to attain a certain estimate accuracy. It is observed that when we want to minimize the number of individuals used, the two-dimensional procedures have a little advantage over the one-dimensional procedures. However, when the major concern is the cost, the one-dimensional procedures clearly outperform the two-dimensional procedures.
- Optimized fast Walsh-Hadamard transform on OpenCL-GPU and OpenCL-CPUPublication . Pereira, Pedro M. M.; Domingues, Patrício; M. M. Rodrigues, Nuno; Faria, Sergio M. M. de; Falcao, GabrielThe Walsh-Hadamard transform plays a major role in many image and video coding algorithms. In one hand, its intensive use in these algorithms makes its acceleration a challenge, in order to speed-up the algorithm execution. On the other hand, the available fast implementations are not efficient across different platforms. In this work, a parallel-based implementation of the WHT is proposed for CPU and GPU platforms using the OpenCL standard. OpenCL achieves portability at code level, but its performance suffers when the same code is used for CPUs and GPUs. To achieve top performance, we propose two WHT versions: OpenCL-GPU for GPUs and OpenCL-CPU for CPUs. Broadly, OpenCL-GPU executed on a GPU runs faster than OpenCL-CPU executed on a multicore CPU, with speedups that range from 120.87 to 1016.35. However, OpenCL-GPU performance drops substantially when ran on a multicore CPU machine, where OpenCL-CPU achieves higher performance, as it exploits the OpenCL support for SIMD instructions.
- STDCC radar at 24 GHz: first measurement trialsPublication . Ferreira Sardo, Andre; Reis, João R.; Duarte, Luis; Leonor, Nuno; Ribeiro, Carlos; Caldeirinha, Rafael F. S.This paper presents the first measurement trials for performance assessment of a real-time and high resolution monostatic radar operating at 24 GHz. The proposed real-time radar, which operates based on the sliding correlation of pseudo-noise (PN) sequences, provides a high time resolution better than 4 ns, useful for moving target identification (MTI) in the presence of highly dense clutter, under harsh environments and severe weather conditions (fog, snow and fire smoke or plume). The STDCC radar target detection capability is demonstrated in this paper, by measuring and identifying the radar data for 4 distinct scenarios, composed of multiple targets (up to 8), inside an anechoic chamber, demonstrating the potential of the proposed radar architecture.