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Publications

2018

Low-cost interrogation system for long period fiber gratings as sensing devices

Authors
Dos Santos P.S.S.; Jorge P.A.S.; De Almeida J.M.M.M.; Coelho L.;

Publication
Optics InfoBase Conference Papers

Abstract
A system with fiber laser diodes and photodetector replaces the usual bulky and expensive systems for characterization of long period fiber gratings and high correlation is achieved when measuring refractive index, temperature and curvature.

2018

Mitigation of Output Fluctuations due to Residual State of Input Polarization in a Compact Current Sensor

Authors
Florida, C; Rosolem, JB; Celaschi, S;

Publication
26th International Conference on Optical Fiber Sensors

Abstract

2018

EyeLSD a Robust Approach for Eye Localization and State Detection

Authors
Eddine, BD; dos Santos, FN; Boulebtateche, B; Bensaoula, S;

Publication
JOURNAL OF SIGNAL PROCESSING SYSTEMS FOR SIGNAL IMAGE AND VIDEO TECHNOLOGY

Abstract
Improving the safety of public roads and industrial factories requires more reliable and robust computer vision-based approaches for monitoring the eye state (open or closed) of human operators. Getting this information in real time when humans are driving cars or using hazardous machinery will help to prevent accidents and deaths. This paper proposes a new framework called EyeLSD to localize the eyes and detect their states without face detection step. For EyeLSD aims, two novel descriptors are proposed: enhanced Pyramidal Local Binary Pattern Histogram (ePLBPH) and Multi-Three-Patch LBP histogram (Multi-TPLBP). The performance of EyeLSD with ePLBPH and Multi-TPLBP is evaluated and compared against other approaches. For this evaluation three independent and public datasets were used: BioID, CAS-PEAL-R1 and ZJU datasets. The set EyeLSD, ePLBPH and Multi-TPLBP have a greater performance when compared against the state-of-the-art algorithms. The proposed approach is very stable under large range of eye appearances caused by expression, rotation, lighting, head pose, and occlusion.

2018

Personalised Dynamic Viewer Profiling for Streamed Data

Authors
Veloso, B; Malheiro, B; Burguillo, JC; Foss, JD; Gama, J;

Publication
WorldCIST (2)

Abstract
Nowadays, not only the number of multimedia resources available is increasing exponentially, but also the crowd-sourced feedback volunteered by viewers generates huge volumes of ratings, likes, shares and posts/reviews. Since the data size involved surpasses human filtering and searching capabilities, there is the need to create and maintain the profiles of viewers and resources to develop recommendation systems to match viewers with resources. In this paper, we propose a personalised viewer profiling technique which creates individual viewer models dynamically. This technique is based on a novel incremental learning algorithm designed for stream data. The results show that our approach outperforms previous approaches, reducing substantially the prediction errors and, thus, increasing the accuracy of the recommendations.

2018

A Parallel-Pipelined OFDM Baseband Modulator with Dynamic Frequency Scaling for 5G Systems

Authors
Ferreira, ML; Ferreira, JC; Hübner, M;

Publication
ARC

Abstract
5G heterogeneity will cover a huge diversity of use cases, ranging from enhanced-broadband to low-throughput and low-power communications. To address such requirements variety, this paper proposes a parallel-pipelined architecture for an OFDM baseband modulator with clock frequency run-time adaptation through dynamic frequency scaling (DFS). It supports a set of OFDM numerologies recently proposed for 5G communication systems. The parallel-pipelined architecture can achieve high throughputs at low clock frequencies (up to 520.3 MSamples/s at 160 MHz) and DFS allows for the adjustment of baseband processing clock frequency according to immediate throughput demands. The application of DFS increases the system’s power efficiency by allowing power savings up to 62.5%; the resource and latency overhead is negligible.

2018

A Generalized Approach to Verification Condition Generation

Authors
Lourenço, CB; Frade, MJ; Nakajima, S; Pinto, JS;

Publication
COMPSAC (1)

Abstract
In a world where many human lives depend on the correct behavior of software systems, program verification assumes a crucial role. Many verification tools rely on an algorithm that generates verification conditions (VCs) from code annotated with properties to be checked. In this paper, we revisit two major methods that are widely used to produce VCs: predicate transformers (used mostly by deductive verification tools) and the conditional normal form transformation (used in bounded model checking of software). We identify three different aspects in which the methods differ (logical encoding of control flow, use of contexts, and semantics of asserts), and show that, since they are orthogonal, they can be freely combined. This results in six new hybrid verification condition generators (VCGens), which together with the fundamental methods constitute what we call the VCGen cube. We consider two optimizations implemented in major program verification tools and show that each of them can in fact be applied to an entire face of the cube, resulting in optimized versions of the six hybrid VCGens. Finally, we compare all VCGens empirically using a number of benchmarks. Although the results do not indicate absolute superiority of any given method, they do allow us to identify interesting patterns.

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