The International Commission on Radiological Protection (ICRP) has created a task group on dose calculations, which, among other objectives, should replace the currently used mathematical MIRD phantoms by voxel phantoms. Voxel phantoms are based on digital images recorded from scanning of real persons by computed tomography or magnetic resonance imaging (MRI). Compared to the mathematical MIRD phantoms, voxel phantoms are true to the natural representations of a human body. Connected to a radiation transport code, voxel phantoms serve as virtual humans for which equivalent dose to organs and tissues from exposure to ionizing radiation can be calculated. The principal database for the construction of the FAX (Female Adult voXel) phantom consisted of 151 CT images recorded from scanning of trunk and head of a female patient, whose body weight and height were close to the corresponding data recommended by the ICRP in Publication 89. All 22 organs and tissues at risk, except for the red bone marrow and the osteogenic cells on the endosteal surface of bone ('bone surface'), have been segmented manually with a technique recently developed at the Departamento de Energia Nuclear of the UFPE in Recife, Brazil. After segmentation the volumes of the organs and tissues have been adjusted to agree with the organ and tissue masses recommended by ICRP for the Reference Adult Female in Publication 89. Comparisons have been made with the organ and tissue masses of the mathematical EVA phantom, as well as with the corresponding data for other female voxel phantoms. The three-dimensional matrix of the segmented images has eventually been connected to the EGS4 Monte Carlo code. Effective dose conversion coefficients have been calculated for exposures to photons, and compared to data determined for the mathematical MIRD-type phantoms, as well as for other voxel phantoms.
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Resumo A utilização da conversão de biomassa é uma solução interessante tanto para a geração energética quanto para a eliminação dos resíduos, de forma menos agressiva ao ambiente. A pirólise é uma reação de decomposição que ocorre pela ação de altas temperaturas. Ocorre a ruptura da estrutura molecular original de um composto pela ação do calor em um ambiente com pouco ou nenhum oxigênio. O processo é autossustentável, pois a decomposição química pelo calor na ausência de oxigênio, produz mais energia do que consome. O processo de pirólise produz biocombustíveis líquidos e gasosos, como bio-óleo e gás de síntese. O principal objetivo na atualidade é o desenvolvimento em escala industrial de plantas para a produção de bio-óleo visando sua aplicação como combustível. Nesta pesquisa pretende-se desenvolver um pirolisador multicombustível capaz de operar com diversos tipos de combustíveis como alternativa tecnológica ao uso de gás natural em UTE (Usinas Termelétricas).Abstract The use of biomass conversion is an interesting solution for both energy generation and for the disposal of waste,in a form less aggressive to the environment. Pyrolysis is a decomposition reaction that occurs by the act of high temperatures. Occurs the rupture of the original molecular structure of a compound by the action of heat in an environment with little or none oxygen. The process is self-sustaining because the chemical decomposition by heat in the absence of oxygen, produces more energy than it consumes. The pyrolysis produces liquid and gas biofuels such as bio-oil and synthesis gas. The main objective nowadays is the development of industrial-scale plant for the production of bio-oil as fuel for their application. This research aims to develop a flex pyrolyzer able to operate with different types of fuels such as technological alternative to the use of natural gas in TPP (Thermal Power Plants).
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