157 research outputs found

    Adaptive sampling in autonomous marine sensor networks

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    Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution June 2006In this thesis, an innovative architecture for real-time adaptive and cooperative control of autonomous sensor platforms in a marine sensor network is described in the context of the autonomous oceanographic network scenario. This architecture has three major components, an intelligent, logical sensor that provides high-level environmental state information to a behavior-based autonomous vehicle control system, a new approach to behavior-based control of autonomous vehicles using multiple objective functions that allows reactive control in complex environments with multiple constraints, and an approach to cooperative robotics that is a hybrid between the swarm cooperation and intentional cooperation approaches. The mobility of the sensor platforms is a key advantage of this strategy, allowing dynamic optimization of the sensor locations with respect to the classification or localization of a process of interest including processes which can be time varying, not spatially isotropic and for which action is required in real-time. Experimental results are presented for a 2-D target tracking application in which fully autonomous surface craft using simulated bearing sensors acquire and track a moving target in open water. In the first example, a single sensor vehicle adaptively tracks a target while simultaneously relaying the estimated track to a second vehicle acting as a classification platform. In the second example, two spatially distributed sensor vehicles adaptively track a moving target by fusing their sensor information to form a single target track estimate. In both cases the goal is to adapt the platform motion to minimize the uncertainty of the target track parameter estimates. The link between the sensor platform motion and the target track estimate uncertainty is fully derived and this information is used to develop the behaviors for the sensor platform control system. The experimental results clearly illustrate the significant processing gain that spatially distributed sensors can achieve over a single sensor when observing a dynamic phenomenon as well as the viability of behavior-based control for dealing with uncertainty in complex situations in marine sensor networks.Supported by the Office of Naval Research, with a 3-year National Defense Science and Engineering Grant Fellowship and research assistantships through the Generic Ocean Array Technology Sonar (GOATS) project, contract N00014-97-1-0202 and contract N00014-05-G-0106 Delivery Order 008, PLUSNET: Persistent Littoral Undersea Surveillance Network

    Electronic Health Records (EHR) and the patient’s empowerment : healthcare management

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    Healthcare systems will face obstacles in the near future to serve patients demands due to a mismatch in the supply of healthcare services. In order to tackle this problem, it will be important to connect the various sources of health information. The introduction of the Electronic Health Record (EHR) is one step towards a more automated healthcare management system. It enables the physicians to easily store, access, analyse and share information. By granting patients online access to their medical records, a new system evolved. Patient Portals offer secure, web-based patient-provider communication services. Since the Patient Portal is a recent technological innovation, little research has been done until now. This dissertation would like to address the problem, whether the healthcare market is ready for the enrolment of Patient Portals. In order to solve the problem statement, the major success and risk attributes are identified and discussed. A primary and secondary research was conducted to identify these attributes. The primary research involved a survey, which asked healthcare professionals to rate preselected success and risk attributes, according to their perceived importance. The findings of the secondary research result from already existing literature. After comparing the results from each source, it is noticeable that a clear answer is hard to provide, since physicians and patients prefer different features and see different obstacles. Referring to the success attributes, scheduling appointments is a major aspect for physicians and patients. Referring to the risk attributes, the loss of personal interaction will be a key obstacle to overcome.Os sistemas de saĂșde enfrentarĂŁo, num futuro prĂłximo, obstĂĄculos Ă  prestação de cuidados mĂ©dicos fruto de faltas na oferta dos serviços de saĂșde. Visando abordar este problema, serĂĄ importante ligar as vĂĄrias fontes de informação de saĂșde. A introdução de Electronic Health Record (EHR) constitui um passo para uma maior automatização dos sistemas de gestĂŁo de saĂșde, permitindo aos mĂ©dicos uma mais fĂĄcil armazenagem, acesso, anĂĄlise e partilha de informação. Ao possibilitar aos pacientes o acesso online aos seus registos mĂ©dicos, um novo sistema evoluiu. Com base na web, os portais oferecem serviços de comunicação seguros entre pacientes e prestadores. Uma vez que o Patient Portal (Portal do Paciente) Ă© uma recente inovação tecnolĂłgica, existe pouca pesquisa sobre a mesma. Este trabalho pretende abordar o problema da preparação do sector da saĂșde para a introdução dos Patient Portals. Assim, os mais importantes atributos de sucesso e de risco sĂŁo identificados e discutidos. A pesquisa primĂĄria envolveu um questionĂĄrio no qual se pedia a profissionais de saĂșde que avaliassem atributos de sucesso e de risco, previamente selecionados, de acordo com o grau de importĂąncia atribuĂ­do. Os resultados da pesquisa secundĂĄria decorrem da literatura existente. ApĂłs comparação dos resultados, Ă© de salientar que Ă© difĂ­cil facultar uma resposta clara, dado que mĂ©dicos e pacientes tĂȘm distintas preferĂȘncias por caracterĂ­sticas e veem diferentes obstĂĄculos. Relativamente aos atributos de sucesso, o agendamento de momentos constitui um aspeto fundamental. Relativamente aos atributos de risco, a perda de interação pessoal serĂĄ um obstĂĄculo central a ultrapassar

    Semeadura de cereais de inverno em diferentes coberturas do solo/ Performance seeder under different cover crops, sowing depth and speed

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    A semeadura sob o sistema plantio direto requer um manejo consciente do solo visando a manutenção de suas caracterĂ­sticas quĂ­micas, fĂ­sicas e biolĂłgicas. Para tanto, a correta utilização da semeadora e a cobertura do solo sĂŁo importantes fatores que interferem na qualidade da semeadura. O objetivo do presente trabalho foi avaliar o desempenho de uma semeadora-adubadora sob sistema plantio direto em diferentes coberturas de solo, profundidades de semeadura e velocidades de deslocamento. Os sistemas de coberturas utilizadas foram: solo em pousio, campo nativo e palha de milho em duas profundidades de semeadura (2 e4 cm) e duas velocidades de deslocamento (7 e11 km/h). O estudo foi realizado na ĂĄrea didĂĄtica e experimental do Instituto Federal do Rio Grande do Sul, CĂąmpus IbirubĂĄ. Foram avaliados o corte de palha, a manutenção da cobertura do solo, as sementes expostas, a profundidade de semeadura e a distĂąncia entre sementes. Nas condiçÔes do experimento a palha de milho apresentou maior resistĂȘncia ao corte. Verificou-se redução da cobertura do solo na ĂĄrea em pousio na maior velocidade. Na ĂĄrea de campo nativo as sementes permaneceram mais superficialmente. A velocidade de semeadura afeta a distĂąncia das sementes na linha, Ă© necessĂĄrio efetuar a regulagem da semeadora de acordo com as condiçÔes da cobertura do solo para se e obter melhor qualidade de semeadura

    The structure of mercantile communities in the Roman world : how open were Roman trade networks?

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    Lista das espécies de aranhas (Arachnida, Araneae) do estado do Rio Grande do Sul, Brasil

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