2019
Autores
Viana, V; Almeida, P; Guardiano, M; Silva, D; Oliveira, B; Guerra, A;
Publicação
The Psychologist: Practice & Research Journal
Abstract
2019
Autores
Ferreira, MC; Universidade do Porto – Faculdade de Engenharia, Porto, Portugal,; Dias, TG; Cunha, JFe;
Publicação
Journal of Traffic and Logistics Engineering
Abstract
2019
Autores
Paiva, LT; Fontes, FACC;
Publicação
DISCRETE AND CONTINUOUS DYNAMICAL SYSTEMS-SERIES B
Abstract
This article addresses the problem of controlling a constrained, continuous-time, nonlinear system through Model Predictive Control (MPC). In particular, we focus on methods to efficiently and accurately solve the underlying optimal control problem (OCP). In the numerical solution of a nonlinear OCP, some form of discretization must be used at some stage. There are, however, benefits in postponing the discretization process and maintain a continuous-time model until a later stage. This is because that way we can exploit additional freedom to select the number and the location of the discretization node points. We propose an adaptive time-mesh refinement (AMR) algorithm that iteratively finds an adequate time-mesh satisfying a pre-defined bound on the local error estimate of the obtained trajectories. The algorithm provides a time-dependent stopping criterion, enabling us to impose higher accuracy in the initial parts of the receding horizon, which are more relevant to MPC. Additionally, we analyze the conditions to guarantee closed-loop stability of the MPC framework using the AMR algorithm. The numerical results show that the proposed AMR strategy can obtain solutions as fast as methods using a coarse equidistant-spaced mesh and, on the other hand, as accurate as methods using a fine equidistant-spaced mesh. Therefore, the OCP can be solved, and the MPC law obtained, faster and/or more accurately than with discrete-time MPC schemes using equidistant-spaced meshes.
2019
Autores
Serra, CR; Almeida, EM; Guerreiro, I; Santos, R; Merrifield, DL; Tavares, F; Oliva Teles, A; Enes, P;
Publicação
SCIENTIFIC REPORTS
Abstract
The gastrointestinal microbiota plays a critical role on host health and metabolism. This is particularly important in teleost nutrition, because fish do not possess some of the necessary enzymes to cope with the dietary challenges of aquaculture production. A main difficulty within fish nutrition is its dependence on fish meal, an unsustainable commodity and a source of organic pollutants. The most obvious sustainable alternatives to fish meal are plant feedstuffs, but their nutritive value is limited by the presence of high levels of non-starch polysaccharides (NSP), which are not metabolized by fish. The composition offish-gut microbial communities have been demonstrated to adapt when the host is fed different ingredients. Thus, we hypothesized that a selective pressure of plant-based diets on fish gut microbiota, could be a beneficial strategy for an enrichment of bacteria with a secretome able to mobilize dietary NSP. By targeting bacterial sporulating isolates with diverse carbohydrase activities from the gut of European sea bass, we have obtained isolates with high probiotic potential. By inferring the adaptive fitness to the fish gut and the amenability to industrial processing, we identified the best two candidates to become industrially valuable probiotics. This potential was confirmed in vivo, since one of the select isolates lead to a better growth and feed utilization efficiency in fish fed probiotic-supplemented plant-based diets, thus contributing for sustainable and more cost-effective aquaculture practices.
2019
Autores
Pinho, LM;
Publicação
Ada User Journal
Abstract
2019
Autores
Matos, T; Faria, CL; Martins, M; Henriques, R; Gonçalves, L;
Publicação
OCEANS 2019 - MARSEILLE
Abstract
A cost-effective (less than 20€) and low-power device is present for in situ continuous monitoring of suspended sediments (SPM) concentration in estuarine and coastal areas. The sensor uses nephelometric technique for SPM values less than 20g/L and backscatter technique for higher ones. A transmitted infrared (IR) and ultraviolet (UV) channels are used to perform the distinguish of inorganic from organic matter in the suspended particles. It is explained the design and built of the sensor as its calibration and preparation for in field tests. The sensor was deployed for one week in a small dock in the estuarine zone of Cavado river (Esposende, Portugal) where is analyzed the SPM and organic/inorganic matter change with the tidal cycles.
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