2020
Autores
Pereira, A; Carvalho, P; Coelho, G; Corte Real, L;
Publicação
IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS FOR VIDEO TECHNOLOGY
Abstract
Color and color differences are critical aspects in many image processing and computer vision applications. A paradigmatic example is object segmentation, where color distances can greatly influence the performance of the algorithms. Metrics for color difference have been proposed in the literature, including the definition of standards such as CIEDE2000, which quantifies the change in visual perception of two given colors. This standard has been recommended for industrial computer vision applications, but the benefits of its application have been impaired by the complexity of the formula. This paper proposes a new strategy that improves the usability of the CIEDE2000 metric when a maximum acceptable distance can be imposed. We argue that, for applications where a maximum value, above which colors are considered to be different, can be established, then it is possible to reduce the amount of calculations of the metric, by preemptively analyzing the color features. This methodology encompasses the benefits of the metric while overcoming its computational limitations, thus broadening the range of applications of CIEDE2000 in both the computer vision algorithms and computational resource requirements.
2020
Autores
Neves Moreira, F; Amorim Lopes, M; Amorim, P;
Publicação
TRANSPORTATION RESEARCH PART E-LOGISTICS AND TRANSPORTATION REVIEW
Abstract
Most vehicle routing approaches disregard the need to refuel fleets. However, planners search for opportunities to refuel at lower prices even if, counter-intuitively, distant fuel stations need to be visited. We propose a novel mathematical formulation and develop branch-and-cut and matheuristic algorithms to efficiently tackle this problem. Results indicate that, to minimize costs, detour distances may increase up to 6 percentage points when fuel stations with lower prices are farther away from the depot. For practice, these insights imply that current policies disregarding station location and/or fuel prices along with "myopic" planning horizons may lead to sub-optimal decisions.
2020
Autores
Nascimento, M; Inacio, P; Paixao, T; Camacho, E; Novais, S; Santos, TG; Braz Fernandes, FMB; Pinto, JL;
Publicação
SENSORS
Abstract
This paper focuses on three main issues regarding Material Extrusion (MEX) Additive Manufacturing (AM) of thermoplastic composites reinforced by pre-functionalized continuous Nickel-Titanium (NiTi) wires: (i) Evaluation of the effect of the MEX process on the properties of the pre-functionalized NiTi, (ii) evaluation of the mechanical and thermal behavior of the composite material during usage, (iii) the inspection of the parts by Non-Destructive Testing (NDT). For this purpose, an optical fiber sensing network, based on fiber Bragg grating and a cascaded optical fiber sensor, was successfully embedded during the 3D printing of a polylactic acid (PLA) matrix reinforced by NiTi wires. Thermal and mechanical perturbations were successfully registered as a consequence of thermal and mechanical stimuli. During a heating/cooling cycle, a maximum contraction of approximate to 100 mu m was detected by the cascaded sensor in the PLA material at the end of the heating step (induced by Joule effect) of NiTi wires and a thermal perturbation associated with the structural transformation of austenite to R-phase was observed during the natural cooling step, near 33.0 degrees C. Regarding tensile cycling tests, higher increases in temperature arose when the applied force ranged between 0.7 and 1.1 kN, reaching a maximum temperature variation of 9.5 +/- 0.1 degrees C. During the unload step, a slope change in the temperature behavior was detected, which is associated with the material transformation of the NiTi wire (martensite to austenite). The embedded optical sensing methodology presented here proved to be an effective and precise tool to identify structural transformations regarding the specific application as a Non-Destructive Testing for AM.
2020
Autores
Au Yong Oliveira, M; Garcia, J; Correia, C;
Publicação
Advances in Intelligent Systems and Computing
Abstract
We live in an age of constant technological evolution where we witness an increasing need for adaptation, in view of market challenges. These transformations create interactions between human beings and machines. This article is a case study based on qualitative and quantitative research, which approaches the implementation of a robotized system in a retail convenience shop, at a petrol station. The main objective was to focus on understanding the applicability of this type of system in a shop, as well as to ascertain its future in the short, medium and long term. Field research performed involved a personal interview with an executive at the Portuguese firm PRIO Energy – the Director of Research, Development and Innovation. The essence of the interview was to enquire about the robot experiment and to understand how innovation occurs, and where the ideas come from. Two other firm employees were also contacted for their testimonials on the project – the convenience store manager and the project innovation manager. Light was shed on which phases the innovation project went through. Finally, the authors has access to the results of a consumer survey involving 210 customers, who interacted with the robot station during its test phase. While not all feedback was good, namely some consumers are concerned that robots will be replacing humans in the workplace, leading to unemployment; the vast majority of the 210 survey respondents saw the experience as positive and one which they would repeat in the future. © The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Switzerland AG 2020.
2020
Autores
Neves, R; Ramos, T; Simionesei, L; Oliveira, A; Grosso, N; Santos, F; Moura, P; Stefan, V; Escorihuela, MJ; Gao, Q; Pérez-Pastor, A; Riquelme, J; Forcén, M; Biddoccu, M; Rabino, D; Bagagiolo, G; Karakaya, N;
Publicação
Abstract
2020
Autores
Pinto A.A.; Zubelli J.P.;
Publicação
Mathematical Biosciences and Engineering
Abstract
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