Experimental validation of a 3-D vision-based measurement system applied to robot calibration

One of the problems that slows the development of off-line programming is the low static and dynamic positioning accuracy of robots. Robot calibration improves the positioning accuracy and can also be used as a diagnostic tool in robot production and maintenance. A large number of robot measurement systems are now available commercially. Yet, there is a dearth of systems that are portable, accurate and low cost. In this work a measurement system that can fill this gap in local calibration is presented. The measurement system consists of a single CCD camera mounted on the robot tool flange with a wide angle lens, and uses space resection models to measure the end-effector pose relative to a world coordinate system, considering radial distortions. Scale factors and image center are obtained with innovative techniques, making use of a multiview approach. The target plate consists of a grid of white dots impressed on a black photographic paper, and mounted on the sides of a 90-degree angle plate. Results show that the achieved average accuracy varies from 0.2mm to 0.4mm, at distances from the target from 600mm to 1000mm respectively, with different camera orientations.

O GPS usado na Batimetria de grandes lagos Amazônicos

É descrita uma metodologia empregando o Global Positioning System, o GPS, no traçado de transectos durante os levantamentos batimétricos realizados em grande lagos amazônicos.

Spatial distribution of schistosomiasis foci on Itamaracá Island, Pernambuco, Brazil

Acute cases of schistosomiasis have been found on the coastal area of Pernambuco, Brazil, due to environmental disturbances and disorderly occupation of the urban areas. This study identifies and spatially marks the main foci of the snail host species, Biomphalaria glabrata on Itamaracá Island. The chaotic occupation of the beach resorts has favoured the emergence of transmission foci, thus exposing residents and tourists to the risk of infection. A database covering five years of epidemiological investigation on snails infected by Schistosoma mansoni in the island was produced with information from the geographic positioning of the foci, number of snails collected, number of snails tested positive, and their infection rate. The spatial position of the foci were recorded through the Global Positioning System (GPS), and the geographical coordinates were imported by AutoCad. The software packages ArcView and Spring were used for data processing and spatial analysis. AutoCad 2000 was used to plot the pairs of coordinates obtained from GPS. Between 1998 and 2002 5009 snails, of which 12.2% were positive for S. mansoni, were collected in Forte Beach. A total of 27 foci and areas of environmental risk were identified and spatially analyzed allowing the identification of the areas exposed to varying degrees of risk.

Variação espacial da resposta do milho à adubação nitrogenada de cobertura em lavoura no cerrado

O objetivo deste trabalho foi avaliar, numa perspectiva espacial, a resposta do milho (Zea mays) à adubação de cobertura com nitrogênio (N) e relacionar a produtividade de grãos com variáveis indicadoras do suprimento desse nutriente. Quatro doses de N foram testadas em 12 parcelas experimentais de 12,6x1.200 m. Em cada parcela foram georreferenciados 11 locais onde foram feitas as avaliações. Nesses locais, foi monitorado o estado nutricional do milho com o clorofilômetro e foram determinados os teores de N mineral do solo e os teores de N na folha e nos grãos. A produtividade de grãos foi mapeada com sensor de produtividade e "Global Positioning System" (GPS) acoplados à colhedora. Os dados foram analisados por estatística clássica e espacial. O cultivo sem aplicação de N em cobertura proporcionou, em média, 77% da máxima produtividade de milho (9,21 Mg ha-1) obtida com a adubação de cobertura. Altas correlações entre leitura do clorofilômetro, teor foliar de N e produtividade do milho, verificadas na análise de médias, não se confirmaram nos mapas que representam a variabilidade espacial dessas variáveis. A interpretação conjunta dos mapas de leitura do clorofilômetro e de produtividade do milho permitiu identificar áreas com diferentes capacidades de suprimento de N pelo solo e subsidiar a delimitação de zonas para o manejo diferenciado do nitrogênio.

Geoambientes do Parque Estadual do Ibitipoca, município de Lima Duarte-MG

Foram identificados, mapeados e caracterizados os geoambientes do Parque Estadual do Ibitipoca (PEI), Minas Gerais, com o objetivo de subsidiar o manejo ecológico da área. Para este fim, realizaram-se coletas de solos, em pontos georreferenciados por GPS (Global Positioning System), fotointerpretações a partir de ortofotos e uso de mapas planialtimétricos, além de intenso reconhecimento de solos no campo. Oito geoambientes foram identificados e caracterizados: (1) Patamares com Espodossolos, 2) Cristas Ravinadas, 3) Escarpas, 4) Grotas, 5) Mata Baixa com Candeia, 6) Mata Alta sobre Xisto, 7) Topos Aplainados e 8) Rampas com Vegetação Aberta. Em cada ambiente a vegetação associada é fortemente condicionada pela profundidade do solo e pelo tempo de permanência de água no sistema. Os ambientes de mata, tanto sobre xistos quanto sobre quartzitos, sofrem menor estresse hídrico, seja por melhores condições físicas do solo e maior retenção de água, seja pela presença de ambiente mais ombrófilo e úmido, como nas Grotas. Os geoambientes florestados possuem concentrações de P e K mais elevadas do que nos ambientes campestres abertos. No geoambiente de Mata Baixa com Candeia, a pobreza química do substrato parece ser o impedimento à ocorrência de uma floresta mais densa. Os Campos de Altitude ocorrem nas altitudes mais elevadas no PEI, sendo desenvolvidos sobre solos mais profundos do que sob campos rupestres, onde há freqüente exposição da rocha ou solos muito rasos.

Metodologia para avaliação do desempenho de receptor de GPS de uso agrícola em condição cinemática

São inúmeras as aplicações das tecnologias de Global Navigation Satellite System (GNSS), e o sistema mais utilizado é o Global Positioning System (GPS), desenvolvido pelos Estados Unidos. Em aplicações agrícolas, há a necessidade de posicionamento estático e cinemático, com demandas de distintos níveis de acurácia. No entanto, os usuários carecem de informação quanto ao desempenho cinemático de receptores GNSS, sendo disponibilizados apenas dados de desempenho estático, e por essa razão desenvolveu-se um veículo instrumentado para testar metodologia de avaliação do desempenho de receptores GNSS sob condição cinemática, visando a representar operações agrícolas. Foi utilizada instrumentação para coletar os dados sob variação de velocidade e sentido de percurso circular. A partir de ensaio experimental, verificou-se que a metodologia possibilita o cálculo da acurácia e da precisão, necessitando apenas de melhorias nos equipamentos de aquisição de dados em ensaios de longa duração.

Análise de detecção de cluster na caracterização espaço-temporal da tuberculose bovina no estado da Bahia

A tuberculose bovina (BTB) é uma enfermidade causada pela infecção pelo Mycobacterium bovis que acomete o homem e diversas espécies de mamíferos. A BTB tem grande importância por causar prejuízos econômicos nas regiões infectadas e por seu impacto na saúde pública. Foi realizado inquérito epidemiológico no Estado da Bahia, entre 2008 e 2010, com o objetivo de estimar a prevalência e conhecer a distribuição espaço temporal da enfermidade. O Estado foi estratificado em quatro regiões, cada uma com características epidemiológicas e demográficas homogêneas representativas de formas de produção pecuária. Um total de 18.810 cabeças com idade superior a 2 anos foi amostrado em 1350 propriedades. O teste cervical comparativo foi aplicado em cada animal selecionado, sendo considerados positivos os animais reagentes positivos ou duas vezes inconclusivos. Latitude e Longitude foram tomadas para cada propriedade amostrada com o auxilio do aparelho de Global Positioning System (GPS). O teste de Cuzick-and-Edwards e a análise de rastreio espacial (spatial scan statistic) foram utilizados para identificar qualquer agrupamento espacial de BTB. A prevalência de rebanho na Bahia, indicando a proporção de propriedades foco, foi de 1,6% (IC 95%: 1,0% - 2,69% por região). Nenhuma evidência significativa (P<0.05) de aglomeração espacial ou clustering foi detectada, possivelmente devido à baixa prevalência da doença. Estes resultados sugerem que a BTB tem baixa prevalência no estado da Bahia e que, nestas condições epidemiológicas, os focos encontrados não podem ser explicados por fatores espacialmente estruturados.

A Test Bed Applied Mobile Robot Navigation

It is presented a test bed applied to studies on dynamics, control, and navigation of mobile robots. A cargo ship scale model was chosen, which can be radio-controlled or operated autonomously through an embedded control system. A control program, which manages on board mission execution, is implemented on a microcontroller. Navigation is based on an electronic compass, which includes automatic compensation for pitch and roll motions. Heading control loop is based on this sensor, and on a rudder positioning system. A propulsion control system is also implemented. Typical manoeuvres as the turning test and "zig-zag", were implemented and tested. They are included on a manoeuvre library, and can be accessed independently or in combined modes. The embedded system is also in charge of signal acquisition and storing during the missions. It is possible to analyse experiments on identification of ship dynamics, control, and navigation, through the data transferred to a PC by serial communication. Navigation is going to be improved by including inertial sensors on board, and a DGPS. Preliminary tests are aimed to ship identification, and manoeuvrability, using free model tests. Future steps include extending this system for developing other mobile robots as, ROVs, AUVs, and aerial vehicles.

Floristic and structural variation of weeds in eucalyptus plantations as influenced by relief and time of year

The objective of this work was to analyze the floristic variation and phytosociological structure of weeds as influenced by relief and time of year in eucalyptus plantations in Santana do Paraíso and Guanhães - MG. The total area sampled for each locality was approximately 10 ± 3 hectares, comprising three types of relief: lowland, slope, and upper area. In each type of relief, 10 plots of 1 m² were sampled, corresponding to 30 plots per locality, where they were randomly allocated in a zigzag. The taxonomic identification was performed in four assessments, corresponding to the months of November and March, comprising two ratings each season, always at the same points, and geo-referenced using the Global Positioning System (GPS). A total of 3,893 individuals, 18 families and 61 species, were identified in Santana do Paraiso and a total of 1,166 individuals, 13 families and 58 species, in Guanhães. In both localities, the most representative families in terms of wealth were: Poaceae, Asteraceae, and Fabaceae. Galinsoga parviflora was the most abundant species. The Vernonia polyantes was identified only in the lowlands, while Arrabida florida was identified in the slope and upper area. On the other hand, Emilia coccinea, Sida rhombifolia, S. paniculatum and Spermacoce latifolia were common to all three environments. Commelina benghalensis was present only in the month of March, while G. parviflora was present only in the month of November. It was concluded that the floristic and phytosociological variation of weeds in eucalyptus plantations is influenced by the type of relief and time of year, which should guide the management practices used in the culture.

The generation and re-generation of social capital and enterprises in multi-stakeholders social cooperative enterprises: a system dynamic approach

Theories on social capital and on social entrepreneurship have mainly highlighted the attitude of social capital to generate enterprises and to foster good relations between third sector organizations and the public sector. This paper considers the social capital in a specific third sector enterprise; here, multi-stakeholder social cooperatives are seen, at the same time, as social capital results, creators and incubators. In the particular enterprises that identify themselves as community social enterprises, social capital, both as organizational and relational capital, is fundamental: SCEs arise from but also produce and disseminate social capital. This paper aims to improve the building of relational social capital and the refining of helpful relations drawn from other arenas, where they were created and from where they are sometimes transferred to other realities, where their role is carried on further (often working in non-profit, horizontally and vertically arranged groups, where they share resources and relations). To represent this perspective, we use a qualitative system dynamic approach in which social capital is measured using proxies. Cooperation of volunteers, customers, community leaders and third sector local organizations is fundamental to establish trust relations between public local authorities and cooperatives. These relations help the latter to maintain long-term contracts with local authorities as providers of social services and enable them to add innovation to their services, by developing experiences and management models and maintaining an interchange with civil servants regarding these matters. The long-term relations and the organizational relations linking SCEs and public organizations help to create and to renovate social capital. Thus, multi-stakeholder cooperatives originated via social capital developed in third sector organizations produce new social capital within the cooperatives themselves and between different cooperatives (entrepreneurial components of the third sector) and the public sector. In their entrepreneurial life, cooperatives have to contrast the "working drift," as a result of which only workers remain as members of the cooperative, while other stakeholders leave the organization. Those who are not workers in the cooperative are (stake)holders with "weak ties," who are nevertheless fundamental in making a worker's cooperative an authentic social multi-stakeholders cooperative. To maintain multi-stakeholder governance and the relations with third sector and civil society, social cooperatives have to reinforce participation and dialogue with civil society through ongoing efforts to include people that provide social proposals. We try to represent these processes in a system dynamic model applied to local cooperatives, measuring the social capital created by the social cooperative through proxies, such as number of volunteers and strong cooperation with public institutions. Using a reverse-engineering approach, we can individuate the determinants of the creation of social capital and thereby give support to governance that creates social capital.

Carbon balance and crop residue management in dynamic equilibrium under a no-till system in Campos Gerais

The adoption of no-tillage systems (NT) and the maintenance of crop residues on the soil surface result in the long-term increase of carbon (C) in the system, promoting C sequestration and reducing C-CO2 emissions to the atmosphere. The purpose of this study was to evaluate the C sequestration rate and the minimum amount of crop residues required to maintain the dynamic C equilibrium (dC/dt = 0) of two soils (Typic Hapludox) with different textural classes. The experiment was arranged in a 2 x 2 x 2 randomized block factorial design. The following factors were analyzed: (a) two soil types: Typic Hapludox (Oxisol) with medium texture (LVTM) and Oxisol with clay texture (LVTA), (b) two sampling layers (0-5 and 5-20 cm), and (c) two sampling periods (P1 - October 2007; P2 - September 2008). Samples were collected from fields under a long-term (20 years) NT system with the following crop rotations: wheat/soybean/black oat + vetch/maize (LVTM) and wheat/maize/black oat + vetch/soybean (LVTA). The annual C sequestration rates were 0.83 and 0.76 Mg ha-1 for LVTM and LVTA, respectively. The estimates of the minimum amount of crop residues required to maintain a dynamic equilibrium (dC/dt = 0) were 7.13 and 6.53 Mg ha-1 year-1 for LVTM and LVTA, respectively. The C conversion rate in both studied soils was lower than that reported in other studies in the region, resulting in a greater amount of crop residues left on the soil surface.

A clinical gamma camera-based pinhole collimated system for high resolution small animal SPECT imaging

The main objective of the present study was to upgrade a clinical gamma camera to obtain high resolution tomographic images of small animal organs. The system is based on a clinical gamma camera to which we have adapted a special-purpose pinhole collimator and a device for positioning and rotating the target based on a computer-controlled step motor. We developed a software tool to reconstruct the target’s three-dimensional distribution of emission from a set of planar projections, based on the maximum likelihood algorithm. We present details on the hardware and software implementation. We imaged phantoms and heart and kidneys of rats. When using pinhole collimators, the spatial resolution and sensitivity of the imaging system depend on parameters such as the detector-to-collimator and detector-to-target distances and pinhole diameter. In this study, we reached an object voxel size of 0.6 mm and spatial resolution better than 2.4 and 1.7 mm full width at half maximum when 1.5- and 1.0-mm diameter pinholes were used, respectively. Appropriate sensitivity to study the target of interest was attained in both cases. Additionally, we show that as few as 12 projections are sufficient to attain good quality reconstructions, a result that implies a significant reduction of acquisition time and opens the possibility for radiotracer dynamic studies. In conclusion, a high resolution single photon emission computed tomography (SPECT) system was developed using a commercial clinical gamma camera, allowing the acquisition of detailed volumetric images of small animal organs. This type of system has important implications for research areas such as Cardiology, Neurology or Oncology.

Periodic dynamic systems for infected hosts and mosquitoes

A mathematical model for the purpose of analysing the dynamic of the populations of infected hosts anf infected mosquitoes when the populations of mosquitoes are periodic in time is here presented. By the computation of a parameter lambda (the spectral radius of a certain monodromy matrix) one can state that either the infection peters out naturally) (lambda <= 1) or if lambda > 1 the infection becomes endemic. The model generalizes previous models for malaria by considering the case of periodic coefficients; it is also a variation of that for gonorrhea. The main motivation for the consideration of this present model was the recent studies on mosquitoes at an experimental rice irrigation system, in the South-Eastern region of Brazil.

Dynamic network data envelopment analysis for university hospitals evaluation

ABSTRACT OBJECTIVE To develop an assessment tool to evaluate the efficiency of federal university general hospitals. METHODS Data envelopment analysis, a linear programming technique, creates a best practice frontier by comparing observed production given the amount of resources used. The model is output-oriented and considers variable returns to scale. Network data envelopment analysis considers link variables belonging to more than one dimension (in the model, medical residents, adjusted admissions, and research projects). Dynamic network data envelopment analysis uses carry-over variables (in the model, financing budget) to analyze frontier shift in subsequent years. Data were gathered from the information system of the Brazilian Ministry of Education (MEC), 2010-2013. RESULTS The mean scores for health care, teaching and research over the period were 58.0%, 86.0%, and 61.0%, respectively. In 2012, the best performance year, for all units to reach the frontier it would be necessary to have a mean increase of 65.0% in outpatient visits; 34.0% in admissions; 12.0% in undergraduate students; 13.0% in multi-professional residents; 48.0% in graduate students; 7.0% in research projects; besides a decrease of 9.0% in medical residents. In the same year, an increase of 0.9% in financing budget would be necessary to improve the care output frontier. In the dynamic evaluation, there was progress in teaching efficiency, oscillation in medical care and no variation in research. CONCLUSIONS The proposed model generates public health planning and programming parameters by estimating efficiency scores and making projections to reach the best practice frontier.

Environmental and agricultural benefits of a management system designed for sandy loam soils of the humid tropics

A sustainable management of soils with low natural fertility on family farms in the humid tropics is a great challenge and overcoming it would be an enormous benefit for the environment and the farmers. The objective of this study was to assess the environmental and agronomic benefits of alley cropping, based on the evaluation of C sequestration, soil quality indicators, and corn yields. Combinations of four legumes were used in alley cropping systems in the following treatments: Clitoria fairchildiana + Cajanus cajan; Acacia mangium + Cajanus cajan; Leucaena leucocephala + Cajanus cajan; Clitoria fairchildiana + Leucaena leucocephala; Leucaena leucocephala + Acacia mangium and a control. Corn was used as a cash crop. The C content was determined in the different compartments of soil organic matter, CEC, available P, base saturation, percentage of water saturation, the period of the root hospitality factor below the critical level and corn yield. It was concluded that alley cropping could substitute the slash and burn system in the humid tropics. The main environmental benefit of alley cropping is the maintenance of a dynamic equilibrium between C input and output that could sustain up to 10 Mg ha-1 of C in the litter layer, decreasing atmospheric CO2 levels. Alley cropping is also beneficial from the agricultural point of view, because it increases base saturation and decreases physical resistance to root penetration in the soil layer 0 - 10 cm, which ensures the increase and sustainability of corn yield.