YOLOv3: Traffic signs & lights detection and recognition for autonomous driving

Advanced Driver Assistance Systems (ADAS) relates to various in-vehicle systems intended to improve road traffic safety by assisting drivers with improved road awareness, inherent dangers and other drivers nearby. Traffic sign detection and recognition is an integral part of ADAS since these provide information about traffic rules, road conditions, route directions and assistance for safe driving. In addition, traffic sign detection and recognition are essential research topics for safe and efficient driving when considering intelligent transportation systems. An approach to traffic sign/light detection and recognition using YOLOv3 and YOLOv3_tiny is presented in this paper in two different environments. The first is on a simulated and real autonomous driving robot for RoboCup Portuguese Open Autonomous Driving Competition. The robot must detect both traffic signs and lights in real-time and behave accordingly. The second environment is on public roads. A computer vision system inside the car points to the road, detecting and classifying traffic signs/lights (T S/L) in different weather and lighting conditions. YOLOv3 and YOLOv3_tiny were tested on both environments with an extensive hyperparameters search. The final result showcases videos of the two algorithms on the two environments.This work has been supported by FCT-Fundacao para a Ciencia e Tecnologia within the R&D Units Project Scope: UIDB/00319/2020. In addition, this work has also been funded through a doctoral scholarship from the Portuguese Foundation for Science and Technology (Fundacao para a Ciencia e a Tecnologia) [grant number SFRH/BD/06944/2020], with funds from the Portuguese Ministry of Science, Technology and Higher Education and the European Social Fund through the Programa Operacional do Capital Humano (POCH)

In situ degradation of YSZ and YSZ + Al2O3 electrolytes of sensors used in glass melting furnaces

This work reports on the degradation of pure YSZ and YSZ +10 wt% alumina composite electrolytes by exposure to the atmosphere of a heat recovery chamber of an industrial glass furnace, at a temperature around 1300 °C. Microstructural observations and impedance spectroscopy measurements were used to evaluate the corrosion effects. YSZ samples directly placed in the sidewalls and intimately exposed to the dusts and volatiles in the atmosphere show strong corrosion effects after short periods. These samples present large amounts of a glassy phase in the intergranular region, containing the same elements as the common batch with inclusion of volatile species from the fuel. At the same time, the average composition of YSZ grains remains almost unchanged. Effects on the electrical properties are obviously stronger in the intergranular response, as confirmed by changes in the typical relaxation frequency. The protection of samples and/or their careful placement in the furnace strongly inhibit the corrosion process. The effectiveness of alumina addition to the YSZ electrolyte in increasing its corrosion resistance was only tested in protected samples, where the corrosion is less severe. For this reason, the expected benefits of this incorporation were found almost irrelevant

Innovative improvement of sintered ceramic electrolytes by salt infiltration

Previously sintered (1500 °C, 4 h) dense pellets of Ce0.9Gd0.1O1.95 (GDC) were covered and heat treated with eutectic mixtures of Na2CO3 and Li2CO3 (NLC), and their electrical performance was assessed against pure GDC and chemically synthesized GDC + NLC. Microstructural analysis of NLC impregnated samples confirmed slight migration of the molten phase to the interior of the GDC pellets via grain boundaries, resulting in a significant improvement of the grain boundary conductivity, increasing with duration of heat treatment (0.5–2 h) and temperature (600–800 °C range). The observed total conductivity exceeded in almost 20% the corresponding values obtained for standard GDC samples. Cells tested before and after direct current polarization (0.5 V, 500 °C) showed the same electrical performance, discarding the possibility of parallel contributions of salt ions to the total conductivity. Grain boundary engineering using salt infiltration is an effective tool to improve the electrical performance of ceramic electrolytes.publishe

Accuracy of generalized gradient approximation functionals for density functional perturbation theory calculations

We assess the validity of various exchange-correlation functionals for computing the structural, vibrational, dielectric, and thermodynamical properties of materials in the framework of density-functional perturbation theory (DFPT). We consider five generalized-gradient approximation (GGA) functionals (PBE, PBEsol, WC, AM05, and HTBS) as well as the local density approximation (LDA) functional. We investigate a wide variety of materials including a semiconductor (silicon), a metal (copper), and various insulators (SiO$_2$ $\alpha$-quartz and stishovite, ZrSiO$_4$ zircon, and MgO periclase). For the structural properties, we find that PBEsol and WC are the closest to the experiments and AM05 performs only slightly worse. All three functionals actually improve over LDA and PBE in contrast with HTBS, which is shown to fail dramatically for $\alpha$-quartz. For the vibrational and thermodynamical properties, LDA performs surprisingly very good. In the majority of the test cases, it outperforms PBE significantly and also the WC, PBEsol and AM05 functionals though by a smaller margin (and to the detriment of structural parameters). On the other hand, HTBS performs also poorly for vibrational quantities. For the dielectric properties, none of the functionals can be put forward. They all (i) fail to reproduce the electronic dielectric constant due to the well-known band gap problem and (ii) tend to overestimate the oscillator strengths (and hence the static dielectric constant)

Model Predictive Control with Safety Constraint Embedded in Hazard and Operability Study

Industrial accidents represent a critical issue in the chemical processes, which keep happening although all efforts to avoid them. There are many tools and methodologies employed in the industry to improve the safety of a chemical system, but they might still fail because accidents do not have a single or linear cause. Recently a new approach to process safety, based on a control-inspired view has gained attention, such as embedding model predictive control (MPC) with safety constraints developed from qualitative safety principles, for instance, HAZOP (Hazard and Operability study). MPC is a control technique formulated as an optimization problem, and consequently, it is possible to include mathematical constraints. In this context, this work proposes to investigate the use of an MPC with safety constraints for potential hazards, integrated with a dynamic simulation-based HAZOP methodology. We evaluated the effect of safety constraints as a recommendation to increase the safeguard of a styrene polymerization reactor, as a case study. To simulate potential hazards from a chemical process failure we used HAZOP deviations, and then evaluated the same disturbance to an MPC with a safety constraint, as a consequence of the HAZOP recommendation to avoid an accident. The simulation results present the effect of the safety constraint in the MPC as a recommendation to safeguard and the importance of the safety approach based on the control-inspired view, enhancing a safety system in a chemical process