Detecting and transporting objects by pushing-only approach

Due to laser scanners’ quality of information, there is a wide spectrum of applica- tions for these sensors in indoor and outdoor, both structured and unstructured environments. Most works present their own case-specific modelling strategies, which are often similar, although presenting no unity or consensus among them. In light of this lack of formalism this dissertation presents an analytical approach for identification and localization of objects using laser sensors. Firstly, the contribution lies in formally defining a laser sensor measurements and their representation, the identification of objects, their main properties and their location in a scene. Sec- ondly, this work presents handling box-shape objects combining mapping, searching, and path planning techniques. Laser scanner data are used to build up a 2D map, which aids the objects’ identification in the scene. Thirdly and most important, the dissertation aims a robust algorithm for pushing objects, from random positions to a final destination. Our main contribution is the route recovery strategy, which reacts whenever the box transportation starts going out of the planned one. It provides robustness to objects rotation and slipping during their displacements, thus guarantees all of them are correctly delivered. Besides, a topological map is created by Voronoi Graph in order to avoid collisions and Dijkstra’s algorithm finds the optimal route. Then, Bézier curves provides suitable paths taking into account the position of the robot, objects and final destination. Finally, simulations are run in V-REP + Matlab, and real experiments validate the proposal, which demonstrates quite efficient for environments without occlusion of the objects to be transported. Keywords: Reactive Object’s Control. Voronoi Graph. Bezier curves. Dijkstra’s algorithm.CAPES (Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

Development of a time and temperature integrator with alkaline phosphatase to investigate the thermal impact of liquid food pasteurization processes.

O processamento térmico de alimentos líquidos consiste na inativação de microrganismos patogênicos, deterioradores e/ou enzimas indesejáveis a altas temperaturas. A avaliação desse processamento pode ser feita utilizando um integrador de tempo e temperatura (TTI). O TTI é um componente termicamente sensível que, intrínseco ou extrínseco ao alimento, permite a determinação do impacto de um processo térmico para obter um alimento seguro. O objetivo deste trabalho foi utilizar a enzima fosfatase alcalina (ALP), em tampão carbonato (força iônica 88 mM) sem sacarose e com sacarose no valor de 10 °Brix, como TTI, para avaliar processos de pasteurização de alimentos líquidos de baixa viscosidade (sucos, leites, néctares e cervejas). A inativação térmica ocorreu entre 55 e 70 °C (sem sacarose) e entre 50 a 95 °C (com sacarose). O tratamento térmico foi realizado utilizando minirreator com micro-ondas focalizadas, a 2450 MHz, em tempos de retenção entre 5 s e 10 min. Para avaliar a atividade enzimática, o método 979.13 da AOAC foi adaptado. A partir da curva de calibração de indofenol com concentrações até 12,0 µg de indofenol/mL da solução enzimática, foi determinada a redução da atividade das soluções dos indicadores enzimáticos com ALP na concentração de 4,0 mg/L. As amostras processadas no minirreator tiveram suas atividades determinadas, conforme o método, utilizando espectrofotômetro UV-Vis a 650 nm e a regressão linear da curva padrão. O modelo cinético D-z (primeira ordem com dois componentes) apresentou bom ajuste, confirmado pelos coeficientes de determinação (0,97, sem sacarose; 0,99, com sacarose) e pelos gráficos de paridades. O indicador sem sacarose apresentou valores de z iguais a 14,0 °C (resistente) e 4,1 °C (lábil) e o indicador com sacarose apresentou valores iguais a 10,0 °C para ambas as frações - este último com resistência adequada para ser utilizado como TTI em processos térmicos de alimentos líquidos. O indicador sem sacarose pode ser usado para avaliação de sub e sobreprocessamento de processos de pasteurização HTST devido às suas frações termorresistente e termolábil, desde que seja usado em temperaturas até 70 °C. O indicador com sacarose apresentou potencial para ser usado como TTI em processos de pasteurização HTST de alimentos líquidos de baixa viscosidade, como sucos, leites, cervejas e néctares, devido à sua maior resistência térmica. Mas está restrito a temperaturas próximas a 70 °C.The thermal processing of liquid foods consists of inactivating pathogenic microorganisms, spoilers and undesirable enzymes at high temperatures. The evaluation of this processing can be done using a time and temperature integrator (TTI). TTI is a thermally sensitive component that, intrinsic or extrinsic to the food, allows the determination of the impact of a thermal process to obtain a safe food. The objective of this work was to use the enzyme alkaline phosphatase (ALP), in carbonate buffer (ionic strength 88 mM) without sucrose and with sucrose in the value of 10 ° Brix, as TTI, to evaluate pasteurization processes of low viscosity liquid foods (juices, milks, nectars and beers). Thermal inactivation occurred between 55 and 70 ° C (without sucrose) and between 50 and 95 ° C (with sucrose). The thermal treatment ocurred using a mini-reactor with focused microwaves, at 2450 MHz, in holding times between 5 s and 10 min. To assess enzyme activity, AOAC method 979.13 was adapted. From the indophenol calibration curve with concentrations up to 12.0 µg of indophenol/mL of the enzyme solution, it was determined a reduction in the activity of the solutions of the enzymatic indicators with ALP at a concentration of 4.0 mg/L. The samples processed in the minireactor had their activities determined, according to the method, using UV-Vis spectrophotometer at 650 nm and linear regression of the standard curve. The D-z kinetic model (first order with two components) showed a good fit, confirmed by the correlation coefficients (0.97, without sucrose; 0.99, with sucrose) and by the parity charts. The sucrose-free indicator showed z values equal to 14.0 ° C (resistant) and 4.1 ° C (labile) and the sucrose indicator showed values equal to 10.0 ° C for both fractions - suitable resistance for use as TTI in liquid food thermal processes. The sucrose-free indicator can be used to evaluate the under and over-processing of HTST pasteurization processes due to its thermoresistant and thermolabile fractions, as long as it is used at temperatures up to 70 ° C. The sucrose indicator has the potential to be used as TTI in HTST pasteurization processes of low viscosity liquid foods, such as juices, milks, beers and nectars, due to its greater thermal resistance. But it is restricted to temperatures close to 70 ° C