Identificação em tempo real de modelo dinâmico de robô móvel com acionamento diferencial e zona morta

Several mobile robots show non-linear behavior, mainly due friction phenomena between the mechanical parts of the robot or between the robot and the ground. Linear models are efficient in some cases, but it is necessary take the robot non-linearity in consideration when precise displacement and positioning are desired. In this work a parametric model identification procedure for a mobile robot with differential drive that considers the dead-zone in the robot actuators is proposed. The method consists in dividing the system into Hammerstein systems and then uses the key-term separation principle to present the input-output relations which shows the parameters from both linear and non-linear blocks. The parameters are then simultaneously estimated through a recursive least squares algorithm. The results shows that is possible to identify the dead-zone thresholds together with the linear parameters

Escalabilidade Paralela de um Algoritmo de Migração Reversa no Tempo (RTM) Pré-empilhamento

The seismic method is of extreme importance in geophysics. Mainly associated with oil exploration, this line of research focuses most of all investment in this area. The acquisition, processing and interpretation of seismic data are the parts that instantiate a seismic study. Seismic processing in particular is focused on the imaging that represents the geological structures in subsurface. Seismic processing has evolved significantly in recent decades due to the demands of the oil industry, and also due to the technological advances of hardware that achieved higher storage and digital information processing capabilities, which enabled the development of more sophisticated processing algorithms such as the ones that use of parallel architectures. One of the most important steps in seismic processing is imaging. Migration of seismic data is one of the techniques used for imaging, with the goal of obtaining a seismic section image that represents the geological structures the most accurately and faithfully as possible. The result of migration is a 2D or 3D image which it is possible to identify faults and salt domes among other structures of interest, such as potential hydrocarbon reservoirs. However, a migration fulfilled with quality and accuracy may be a long time consuming process, due to the mathematical algorithm heuristics and the extensive amount of data inputs and outputs involved in this process, which may take days, weeks and even months of uninterrupted execution on the supercomputers, representing large computational and financial costs, that could derail the implementation of these methods. Aiming at performance improvement, this work conducted the core parallelization of a Reverse Time Migration (RTM) algorithm, using the parallel programming model Open Multi-Processing (OpenMP), due to the large computational effort required by this migration technique. Furthermore, analyzes such as speedup, efficiency were performed, and ultimately, the identification of the algorithmic scalability degree with respect to the technological advancement expected by future processors

Construção e análise de desempenho de um fogão solar à concentração utilizando dois focos para cozimento direto

A model of a solar oven with a reflective surface composed of two mirror segments is presented, constituting a two semi-parabolic surfaces made of fiberglass, applied on a ceramic mold, intended to be used in residential and commercial cooking. The reflective surface of the semi-parable is obtained with the use of multiple plain segments of 2 mm wide mirrors. The semi-parabolic structure has visible movements that are comparable to that of the sun. The technical details of the manufacturing and assembling processes will be presented with an analysis of the viability of thermal, economic, and materials of such prototype. This prototype has important social implications and primordial aspects, which combats the ecological damages caused by the wide-scale use of firewood during cooking. It has been demonstrated that the solar oven has the capacity to cook simultaneous two meals distinct for a family of four

Análise do efeito do tempo da moagem de alta energia no tamanho de cristalito e microdeformação da rede cristalina do WC-Co

Hard metals are the composite developed in 1923 by Karl Schröter, with wide application because high hardness, wear resistance and toughness. It is compound by a brittle phase WC and a ductile phase Co. Mechanical properties of hardmetals are strongly dependent on the microstructure of the WC Co, and additionally affected by the microstructure of WC powders before sintering. An important feature is that the toughness and the hardness increase simultaneously with the refining of WC. Therefore, development of nanostructured WC Co hardmetal has been extensively studied. There are many methods to manufacture WC-Co hard metals, including spraying conversion process, co-precipitation, displacement reaction process, mechanochemical synthesis and high energy ball milling. High energy ball milling is a simple and efficient way of manufacturing the fine powder with nanostructure. In this process, the continuous impacts on the powders promote pronounced changes and the brittle phase is refined until nanometric scale, bring into ductile matrix, and this ductile phase is deformed, re-welded and hardened. The goal of this work was investigate the effects of highenergy milling time in the micro structural changes in the WC-Co particulate composite, particularly in the refinement of the crystallite size and lattice strain. The starting powders were WC (average particle size D50 0.87 μm) supplied by Wolfram, Berglau-u. Hutten - GMBH and Co (average particle size D50 0.93 μm) supplied by H.C.Starck. Mixing 90% WC and 10% Co in planetary ball milling at 2, 10, 20, 50, 70, 100 and 150 hours, BPR 15:1, 400 rpm. The starting powders and the milled particulate composite samples were characterized by X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) to identify phases and morphology. The crystallite size and lattice strain were measured by Rietveld s method. This procedure allowed obtaining more precise information about the influence of each one in the microstructure. The results show that high energy milling is efficient manufacturing process of WC-Co composite, and the milling time have great influence in the microstructure of the final particles, crushing and dispersing the finely WC nanometric order in the Co particles

Análise de desempenho de um fogão solar construído a partir de sucatas de antena de tv

Given the growing environmental crisis caused by degradation, mainly due to the use of polluting energy sources, increasing the growing use of renewable energies worldwide, with emphasis on solar energy, an abundant supply and available to everyone, which can be harnessed in several ways: electricity generation; dehydration of food; heating, disinfection and distillation and cooking. The latter has as its primary feature the viability of clean, renewable energy for society, combating ecological damage caused by large-scale use of firewood for cooking foods, use in tropical countries with high solar radiation, and has funding NGOs throughout the world with the goal of achieving low-income population. The proposed project consists of a solar cooker for concentration, working from the reflection of sunlight by a hub that they converge to a focal point at the bottom of the pot, getting lots of heat. The solar cooker under study consists of two elliptical reflecting parabolas made from the recycling of scrap TV antenna, having 0.29 m² of surface area for each antenna, which were covered by multiple mirrors of 2 mm thick and mounted on a metal structure, with correction for the mobility of the apparent movement of the sun. This structure was built with the recycling of scrap metal, possessing a relatively low cost compared with other solar cookers, around US$ 50.00. This cost becomes negligible, since that will involve a great benefit to not have fuel costs for each meal, unlike the use of gas or firewood for cooking food. The tests show that the cooker has reached the maximum temperature of 740 ° C, for boiling water in an average time of 28 minutes, cooking various types of foods such as potatoes, rice and pasta in an average time of 45 minutes and still going as a solar oven, making pizza baking and meat. These cooking times do not differ much from the cooking times on a gas stove, it becomes the solar cooker as a good consumer acceptance, and furthermore not to deliver the same gases that can poison the food as with the wood stove. Proves the viability of using the stove to cook or bake in two daily meals for a family, still presenting a position to improve his performance with the addition of new materials, equipment and techniques

Influência da corrente de pulso, do tempo de pulso e diâmetro de gota sobre a estabilidade da transferência metálica no processo MIG-P

To obtain a process stability and a quality weld bead it is necessary an adequate parameters set: base current and time, pulse current and pulse time, because these influence the mode of metal transfer and the weld quality in the MIG-P, sometimes requiring special sources with synergistic modes with external control for this stability. This work aims to analyze and compare the effects of pulse parameters and droplet size in arc stability in MIG-P, four packets of pulse parameters were analysed: Ip = 160 A, tp = 5.7 ms; Ip = 300 A and tp = 2 ms, Ip = 350 A, tp = 1.2 ms and Ip = 350 A, tp = 0.8 ms. Each was analyzed with three different drop diameters: drop with the same diameter of the wire electrode; droplet diameter larger drop smaller than the diameter of the wire electrode. For purposes of comparison the same was determined relation between the average current and welding speed was determined generating a constant (Im / Vs = K) for all parameters. Welding in flat plate by simple deposition for the MIG-P with a distance beak contact number (DBCP) constant was perfomed subsequently making up welding in flat plate by simple deposition with an inclination of 10 degrees to vary the DBCP, where by assessment on how the MIG-P behaved in such a situation was possible, in addition to evaluating the MIG-P with adaptive control, in order to maintain a constant arc stability. Also high speed recording synchronized with acquiring current x voltage (oscillogram) was executed for better interpretation of the transfer mechanism and better evaluation in regard to the study of the stability of the process. It is concluded that parameters 3 and 4 exhibited greater versatility; diameters drop equal to or slightly less than the diameter of the wire exhibited better stability due to their higher frequency of detachment, and the detachment of the drop base does not harm the maintenance the height of the arc

Efeito de variáveis de processo no tempo de fermentação e na concentração das dicetonas vicinais totais

Among the main challenges in the beer industrial production is the market supply at the lowest cost and high quality, in order to ensure the expectations of customers and. consumers The beer fermentation stage represents approximately 70% of the whole time necessary to its production, having a obligatoriness of strict process controls to avoid becoming bottleneck in beer production. This stage is responsible for the formation of a series of subproducts, which are responsible for the composition of aroma/bouquet existing in beer and some of these subproducts, if produced in larger quantities, they will confer unpleasant taste and odor to the final product. Among the subproducts formed during the fermentation stage, total vicinal diketones is the main component, since it is limiting for product transfusion to the subsequent steps, besides having a low perception threshold by the consumer and giving undesirable taste and odor. Due to the instability of main raw materials quality and also process controls during fermentation, the development of alternative forms of beer production without impacting on total fermentation time and final product quality is a great challenge to breweries. In this work, a prior acidification of the pasty yeast was carried out, utilizing for that phosphoric acid, food grade, reducing yeast pH of about 5.30 to 2.20 and altering its characteristic from flocculent to pulverulent during beer fermentation. An increase of six times was observed in amount of yeast cells in suspension in the second fermentation stage regarding to fermentations by yeast with no prior acidification. With alteration on two input variables, temperature curve and cell multiplication, which goal was to minimize the maximum values for diketones detected in the fermenter tank, a reduction was obtained from peak of formed diacetyl and consequently contributed to reduction in fermentation time and total process time. Several experiments were performed with those process changes in order to verify the influence on the total fermentation time and total vicinal diketones concentration at the end of fermentation. This experiment reached as the best production result a total fermentation time of 151 hours and total vicinal diketone concentration of 0.08 ppm. The mass of yeast in suspension in the second phase of fermentation increased from 2.45 x 106 to 16.38 x 106 cells/mL of yeast, which fact is key to a greater efficiency in reducing total vicinal diketones existing in the medium, confirming that the prior yeast acidification, as well as the control of temperature and yeast cell multiplication in fermentative process enhances the performance of diketones reduction and consequently reduce the total fermentation time with diketones concentration below the expected value (Max: 0.10 ppm)

Monitoramento em tempo real de processos fermentativos por espectroscopia no infravermelho próximo (NIRS)

A chemical process optimization and control is strongly correlated with the quantity of information can be obtained from the system. In biotechnological processes, where the transforming agent is a cell, many variables can interfere in the process, leading to changes in the microorganism metabolism and affecting the quantity and quality of final product. Therefore, the continuously monitoring of the variables that interfere in the bioprocess, is crucial to be able to act on certain variables of the system, keeping it under desirable operational conditions and control. In general, during a fermentation process, the analysis of important parameters such as substrate, product and cells concentration, is done off-line, requiring sampling, pretreatment and analytical procedures. Therefore, this steps require a significant run time and the use of high purity chemical reagents to be done. In order to implement a real time monitoring system for a benchtop bioreactor, these study was conducted in two steps: (i) The development of a software that presents a communication interface between bioreactor and computer based on data acquisition and process variables data recording, that are pH, temperature, dissolved oxygen, level, foam level, agitation frequency and the input setpoints of the operational parameters of the bioreactor control unit; (ii) The development of an analytical method using near-infrared spectroscopy (NIRS) in order to enable substrate, products and cells concentration monitoring during a fermentation process for ethanol production using the yeast Saccharomyces cerevisiae. Three fermentation runs were conducted (F1, F2 and F3) that were monitored by NIRS and subsequent sampling for analytical characterization. The data obtained were used for calibration and validation, where pre-treatments combined or not with smoothing filters were applied to spectrum data. The most satisfactory results were obtained when the calibration models were constructed from real samples of culture medium removed from the fermentation assays F1, F2 and F3, showing that the analytical method based on NIRS can be used as a fast and effective method to quantify cells, substrate and products concentration what enables the implementation of insitu real time monitoring of fermentation processes

Otimização do tempo e temperatura no processamento da gipsita oriunda dos cristalizadores da produção de sal para obter gesso de uso na construção civil

During the process of the salt production, the first the salt crystals formed are disposed of as industrial waste. This waste is formed basically by gypsum, composed of calcium sulfate dihydrate (CaSO4.2H2O), known as carago cru or malacacheta . After be submitted the process of calcination to produce gypsum (CaSO4.0,5H2O), can be made possible its application in cement industry. This work aims to optimize the time and temperature for the process of calcination of the gypsum (carago) for get beta plaster according to the specifications of the norms of civil construction. The experiments involved the chemical and mineralogical characterization of the gypsum (carago) from the crystallizers, and of the plaster that is produced in the salt industry located in Mossoró, through the following techniques: x-ray diffraction (XRD), x-ray fluorescence (FRX), thermogravimetric analysis (TG/DTG) and scanning electron microscopy (SEM) with EDS. For optimization of time and temperature of the process of calcination was used the planning three factorial with levels with response surfaces of compressive mechanical tests and setting time, according norms NBR-13207: Plasters for civil construction and x-ray diffraction of plasters (carago) beta obtained in calcination. The STATISTICA software 7.0 was used for the calculations to relate the experimental data for a statistical model. The process for optimization of calcination of gypsum (carago) occurred in the temperature range from 120° C to 160° C and the time in the range of 90 to 210 minutes in the oven at atmospheric pressure, it was found that with the increase of values of temperature of 160° C and time calcination of 210 minutes to get the results of tests of resistance to compression with values above 10 MPa which conform to the standard required (> 8.40) and that the X-ray diffractograms the predominance of the phase of hemidrato beta, getting a beta plaster of good quality and which is in accordance with the norms in force, giving a by-product of the salt industry employability in civil construction

Assimilação do IWV-GPS no Brasil: otimização das estimativas do atraso zenital troposférico em tempo real

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Avaliação das previsões do atraso zenital troposférico para a América do Sul, obtidas usando modelo de previsão numérica de tempo com alta resolução espacial

A Center for Weather Forecast and Climatic Studies of National Institute for Space Research (CPTEC/INPE) has provided to the Brazilian Geodetic community, since 2004, an alternative to correct the GNSS observables from the tropospheric refraction. Numerical Weather Prediction (NWP) Model is used to generate Zenital Tropospheric Delay (ZTD). For the version 1, it was developed a model with horizontal resolution of 100 km, which was updated with Eta model, with resolution of 20 km. This paper provides the most significative details of the current version, as well an evaluation of its quality, using for such ZTD estimates from GPS data collect at RBMC. Comparing to the old version, considerable improvement could be observed from the new model, mainly in Brasilia and Curitiba, reaching up to 55% improvement. When all stations were used in the quality control, almost null bias and RMS of about 4 to 5 cm could be observed.

Análise tempo-intensidade dos estímulos doce e amargo de extrato de folhas de estévia [Stevia rebaudiana (Bert.) Bertoni] em doçura equivalente a sacarose

O extrato de folhas de estévia (Stevia rebaudiana Bertoni) é o único edulcorante utilizado na substituição da sacarose, que pode ser produzido totalmente no Brasil. O objetivo deste estudo foi determinar os comportamentos de características temporais dos estímulos doce e amargo da estevia em doçuras equivalentes a soluções de sacarose (DESS) a 3 e 10%. As curvas tempo-intensidade (T-I) para cada substância foram coletadas utilizando-se o programa Sistema de Coleta de Dados Tempo-Intensidade - SCDTI para Windows, onde os provadores registravam com auxílio do mouse a percepção de cada estímulo solicitado em função do tempo, para cada amostra. Os parâmetros das curvas T-I coletados foram: tempo de intensidade máxima (TImax), intensidade máxima (Imax), tempo onde a intensidade máxima começa a declinar (Td), tempo de platô (Platô), área sob a curva (Área) e tempo total de duração do estímulo (Ttot). Os parâmetros Td, Ttot, Área e Platô das curvas T-I para o estímulo doce nos dois níveis de doçura foram significativamente superiores para estévia, enquanto TImax e Imax foram significativamente menores (p£0,05), sendo que as diferenças entre os valores para as duas substâncias foram muito maiores a DESS a 10%. A sacarose não apresentou nenhum registro para o estímulo amargo tanto a 3 como a 10%, enquanto a estévia apresentou curvas T-I características, com intensidade e o tempo total de duração dependente da concentração.

Análise tempo-intensidade dos gostos doce e amargo de extrato de folhas de estévia (Stévia rebaudiana Bertoni) em doçura equivalente a sacarose

O extrato de folhas de estévia (Stévia rebaudiana Bertoni) é o único edulcorante utilizado na substituição da sacarose, que pode ser produzido totalmente no Brasil. Este trabalho objetivou determinar o comportamento de características temporais dos estímulos doce e amargo do extrato de estévia em doçuras equivalentes a soluções de sacarose (DESS) a 3 e 10%. As curvas tempo-intensidade (T-I) para cada substância foram coletadas utilizando-se o programa Sistema de Coleta de Dados Tempo-Intensidade - SCDTI para Windows, onde os provadores registravam com auxílio do mouse a percepção de cada estímulo solicitado em função do tempo, para cada amostra. Os parâmetros das curvas T-I determinados foram: tempo de intensidade máxima (TImax), intensidade máxima (Imax), tempo onde a intensidade máxima começa a declinar (Td), tempo de platô (Platô), área sob a curva (Área) e tempo total de duração do estímulo (Ttot). Os parâmetros Td, Ttot, Área e Platô das curvas T-I para o estímulo doce nos dois níveis de doçura significativamente foram superiores para o extrato de estévia, enquanto TImax e Imax foram significativamente menores (p£ 0,05). As diferenças entre os valores de sacarose e extrato de estévia foram muito maiores a DESS a 10%. A sacarose não apresentou nenhum registro para o estímulo amargo tanto a 3 como a 10%, enquanto a estévia apresentou curvas T-I características, com intensidade e o tempo total de duração dependente da concentração.

Relações entre mídia e lazer:o capitalismo, os meios e a apropriação do tempo livre nas sociedades industrial e pós-industrial

This research aims to understand the relationship between media, capitalism and ownership of free time for leisure practices in industrial societies and postindustrial. Searching is thus a conceptual framework that takes into account the kind of ideology that naturalizes the relationship of leisure with the foundations of contemporary media, and the media only with leisure, forgetting their insertion in the labor and industrial relations in society. We intend to demonstrate that every mode of production, in the capitalist system, entails a mode of reproduction. Methodologically, this is a first approximation, from theoretical concerns already performed, constituting a theoretical research, bibliographic and descriptive character. The results of the text drives us to the conclusion that the work and leisure spheres tend to be less and less differentiated, since both remain as activities of product management with the same intellective protocols, based on information and communication technology, and that accordingly, the media favors an expansion of productive activity even during leisure time

Pressupostos ontológicos para se pensar a nova tecnologia: técnica, informação e ser e tempo

La recherche presentée, realisée sur le domaine de la méthaphysique, s´agit de rassembler des pressupositions pour une fondamentation ontologique de la technologie de l´Information, basé sur la philophie de Martin Heidegger; foncièrement, sur l´analytique existentiel du Dasein dans l´ouvrage Être et Temps. À partir de la pensée sur ce qui est aujourd´hui , il s´agit d´investiguer sur quels fondaments la Nouvelle Tecnologie se fut érigée de façon a que nous sommes engajés au projet de numérisation des étants que en même temps que destine l´homme a l´oubli de l´Être, l´offre la possibilité de transformation. Le rapport entre la question de l´Être et la question de la technique est analysé comme des chemins croisés et dans ce carrefour il devient possible penser ce qui est technique, ce qui est information pour Heidegger et de quel façon les modes existentiels du Dasein sont prêtes pour caractériser l ´homme au sein de la tecnologie de l´information. Par cette appropriation, il reste penser comment c´est possible l´ouverture d´une perspective de reconduction de l´homme à la vérité de l´Être. Finalement, la structuration des fondements rends possible la réflexion discursive général: avec qui nous nous ocuppons, comme nous sommes, dans quelle direction nous nous acheminons, les thèmes générales, respectivement, des trois chapitres. Les points d´investigation du premier chapitre son: a) La caractérisation précise du Dasein, appuyé sur des considerations de Benedito Nunes, Hans-Georg Gadamer, Jacques Derrida et Rüdiger Safränski; b) Le concept de technique et son essence chez Heidegger; c) la distinction entre technique et technologie, appuyé sur le pensée de J. Ellul, Michel Séris, Otto Pöggeler, Michel Haar, Dominique Janicaud; c) Le concept de cibernetique chez Heidegger et chez Norbert Wiener; d) La caractérisation preliminaire d´information, l´analyse étimologique e philosophique, l´avis de Heidegger te les théories de Rafael Capurro; f) L´Analyse du phénomène de la numérisation des étants, des considérations de Virilio, et l´analyse d´un concept de virtuel avec Henri Bergson et Gilles Deleuze. Dans le deuxième chapitre, l´analyse des existentiels du Dasein vers le sommaire des fondements de base pour la caractérisation de la technologie de l´information comme un problème philosophique. Finalement, aprés avoir presenté les concepts introdutoires que délimitent le questionement, suivi par les indications et pressupositions ontologiques trouvés sur Être et Temps, le troisième chapitre disserte sur le péril, ce qui sauve et la sérénité, les trois mots-clés de la pensée heideggerienne sur la technique que permettent l´approche conclusif de la question