614 research outputs found

    Use of control umbilicals as a deployment mode for free flying telerobotic work systems

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    Work to date on telerobotic work systems for use in space generally consider two deployment modes, free flying, or fixed within a limited work envelope. Control tethers may be employed to obtain a number of operational advantages and added flexibility in the basing and deployment of telerobotic work systems. Use of a tether allows the work system to be separated into two major modules, the remote work package and the control module. The Remote Work Package (RWP) comprises the free flying portion of the work system while the Control Module (CM) remains at the work system base. The chief advantage of this configuration is that only the components required for completion of the work task must be located at the work site. Reaction mass used in free flight is stored at the Control module and supplied to the RWP through the tether, eliminating the need for the RWP to carry it. The RWP can be made less massive than a self contained free flying work system. As a result, reaction mass required for free flight is lower than for a self contained free flyer

    Procedimento prático para elaboração de uma tabela de produção.

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    Modeling and Real-Time Simulation of a Vascularized Liver Tissue

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    International audienceIn Europe only, about 100,000 deaths per year are related to cirrhosis or liver cancer. While surgery remains the option that offers the foremost success rate against such pathologies, several limitations still hinder its widespread development. Among the limiting factors is the lack of accurate planning systems, which has been a motivation for several recent works, aiming at better resection planning and training systems, relying on pre-operative imaging, anatomical and biomechanical modelling. While the vascular network in the liver plays a key role in defining the operative strategy, its influence at a biomechanical level has not been taken into account. In the paper we propose a real-time model of vascularized organs such as the liver. The model takes into account separate constitutive laws for the parenchyma and vessels, and defines a coupling mechanism between these two entities. In the evaluation section, we present results of in vitro porcine liver experiments that indicate a significant influence of vascular structures on the mechanical behaviour of tissue. We confirm the val- ues obtained in the experiments by computer simulation using standard FEM. Finally, we show that the conventional modelling approach can be efficiently approximated with the proposed composite model capable of real-time calculations

    Índices de sítios para Hovenia dulcis Thunberg na região central do estado do Rio Grande do Sul, Brasil.

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    Este trabalho teve como objetivo construir curvas índice de sítios florestais, a partir da altura dominante e idade, de populações localizadas na região central do Estado do Rio Grande do Sul. Para tanto, foram utilizadas informações de três povoamentos (sítios) com idades de 25 anos, localizados na Fundação de Pesquisa Agropecuária (FEPAGRO). Para classificar os sítios florestais, coletaram-se informações de 18 árvores dominantes nos locais, observando a metodologia para análise de tronco. Na construção das curvas de índice de sítio, foi o selecionado o modelo de Backman, ficando constatada a necessidade da construção de dois conjuntos de curvas, com intervalo de 2 m, da idade de 5 a 25 anos, com idade índice de 25 anos. Para o Sítio I-A, foram geradas 3 curvas índices, de 22 a 24 m e, para os Sítios I-B+II+III, 6 curvas índices de 8 a 18 m

    Parallelized Incomplete Poisson Preconditioner in Cloth Simulation

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    Efficient cloth simulation is an important problem for interactive applications that involve virtual humans, such as computer games. A common aspect of many methods that have been developed to simulate cloth is a linear system of equations, which is commonly solved using conjugate gradient or multi-grid approaches. In this paper, we introduce to the computer gaming community a recently proposed preconditioner, the incomplete Poisson preconditioner, for conjugate gradient solvers. We show that the parallelized incomplete Poisson preconditioner (PIPP) performs as well as the current state-of-the-art preconditioners, while being much more amenable to standard thread-level parallelism. We demonstrate our results on an 8-core Apple* Mac* Pro and a 32-core code name Emerald Ridge system

    Como classificar sítios florestais através da altura dominante do povoamento.

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    bitstream/CNPF-2009-09/44070/1/Doc166.pd

    Identificação das sub-tipologias de um compartimento de floresta tropical no Estado do Acre com fins de manejo.

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    As florestas naturais tropicais são extremamente heterogêneas e requerem ferramentas ágeis para análise, principalmente quando sua finalidade é o manejo. Atualmente existem metodologias ligadas a análise multivariada, pesquisa operacional e SIG pouco utilizadas quando o objetivo específico é o de manejar uma floresta. O programa TWINSPAN (Two-way Indicator Species Analyis) utiliza um processo multivariado, que é um método hierárquico, divisivo e politético, ou seja, utiliza técnicas que empregam uma função de semelhança ou função objetiva baseada num conjunto de características. O programa TWINSPAN constrói uma tabela bidimensional pela identificação de espécies preferenciais. As parcelas são classificadas primeiro por dicotimização sucessiva e, posteriormente, as espécies pelo mesmo processo. Em cada divisão é calculado um autovalor (eigenvalue) que indica o percentual de variação dos dados da comunidade, explicada no eixo de ordenação. Nesse sentido, este trabalho foi realizado com o objetivo de identificar a possibilidade de sub-compartimetalização baseado nas possíveis sub-tipologias, determinando agrupamentos florísticos distintos, em um compartimento florestal no estado do Acre, região Norte do Brasil e, assim, fornecer subsídios básicos para fins de manejar a floresta

    Synthetic biology to access and expand nature's chemical diversity

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    Bacterial genomes encode the biosynthetic potential to produce hundreds of thousands of complex molecules with diverse applications, from medicine to agriculture and materials. Accessing these natural products promises to reinvigorate drug discovery pipelines and provide novel routes to synthesize complex chemicals. The pathways leading to the production of these molecules often comprise dozens of genes spanning large areas of the genome and are controlled by complex regulatory networks with some of the most interesting molecules being produced by non-model organisms. In this Review, we discuss how advances in synthetic biology — including novel DNA construction technologies, the use of genetic parts for the precise control of expression and for synthetic regulatory circuits — and multiplexed genome engineering can be used to optimize the design and synthesis of pathways that produce natural products
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