54 research outputs found

    Wavelet Based Fractal Analysis of Airborne Pollen

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    The most abundant biological particles in the atmosphere are pollen grains and spores. Self protection of pollen allergy is possible through the information of future pollen contents in the air. In spite of the importance of airborne pol len concentration forecasting, it has not been possible to predict the pollen concentrations with great accuracy, and about 25% of the daily pollen forecasts have resulted in failures. Previous analysis of the dynamic characteristics of atmospheric pollen time series indicate that the system can be described by a low dimensional chaotic map. We apply the wavelet transform to study the multifractal characteristics of an a irborne pollen time series. We find the persistence behaviour associated to low pollen concentration values and to the most rare events of highest pollen co ncentration values. The information and the correlation dimensions correspond to a chaotic system showing loss of information with time evolution.Comment: 11 pages, 7 figure

    The DEMO magnet system – Status and future challenges

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    We present the pre-concept design of the European DEMO Magnet System, which has successfully passed the DEMO plant-level gate review in 2020. The main design input parameters originate from the so-called DEMO 2018 baseline, which was produced using the PROCESS systems code. It defines a major and minor radius of 9.1 m and 2.9 m, respectively, an on-axis magnetic field of 5.3 T resulting in a peak field on the toroidal field (TF) conductor of 12.0 T. Four variants, all based on low-temperature superconductors (LTS), have been designed for the 16 TF coils. Two of these concepts were selected to be further pursued during the Concept Design Phase (CDP): the first having many similarities to the ITER TF coil concept and the second being the most innovative one, based on react-and-wind (RW) Nb3Sn technology and winding the coils in layers. Two variants for the five Central Solenoid (CS) modules have been investigated: an LTS-only concept resembling to the ITER CS and a hybrid configuration, in which the innermost layers are made of high-temperature superconductors (HTS), which allows either to increase the magnetic flux or to reduce the outer radius of the CS coil. Issues related to fatigue lifetime which emerged in mechanical analyses will be addressed further in the CDP. Both variants proposed for the six poloidal field coils present a lower level of risk for future development. All magnet and conductor design studies included thermal-hydraulic and mechanical analyses, and were accompanied by experimental tests on both LTS and HTS prototype samples (i.e. DC and AC measurements, stability tests, quench evolution etc.). In addition, magnet structures and auxiliary systems, e.g. cryogenics and feeders, were designed at pre-concept level. Important lessons learnt during this first phase of the project were fed into the planning of the CDP. Key aspects to be addressed concern the demonstration and validation of critical technologies (e.g. industrial manufacturing of RW Nb3Sn and HTS long conductors, insulation of penetrations and joints), as well as the detailed design of the overall Magnet System and mechanical structures

    Plasma physics and control studies planned in JT-60SA for ITER and DEMO operations and risk mitigation

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    | openaire: EC/H2020/633053/EU//EUROfusionA large superconducting machine, JT-60SA has been constructed to provide major contributions to the ITER program and DEMO design. For the success of the ITER project and fusion reactor, understanding and development of plasma controllability in ITER and DEMO relevant higher beta regimes are essential. JT-60SA has focused the program on the plasma controllability for scenario development and risk mitigation in ITER as well as on investigating DEMO relevant regimes. This paper summarizes the high research priorities and strategy for the JT-60SA project. Recent works on simulation studies to prepare the plasma physics and control experiments are presented, such as plasma breakdown and equilibrium controls, hybrid and steady-state scenario development, and risk mitigation techniques. Contributions of JT-60SA to ITER and DEMO have been clarified through those studies.Peer reviewe

    Operating a full tungsten actively cooled tokamak: overview of WEST first phase of operation

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    WEST is an MA class superconducting, actively cooled, full tungsten (W) tokamak, designed to operate in long pulses up to 1000 s. In support of ITER operation and DEMO conceptual activities, key missions of WEST are: (i) qualification of high heat flux plasma-facing components in integrating both technological and physics aspects in relevant heat and particle exhaust conditions, particularly for the tungsten monoblocks foreseen in ITER divertor; (ii) integrated steady-state operation at high confinement, with a focus on power exhaust issues. During the phase 1 of operation (2017–2020), a set of actively cooled ITER-grade plasma facing unit prototypes was integrated into the inertially cooled W coated startup lower divertor. Up to 8.8 MW of RF power has been coupled to the plasma and divertor heat flux of up to 6 MW m−2 were reached. Long pulse operation was started, using the upper actively cooled divertor, with a discharge of about 1 min achieved. This paper gives an overview of the results achieved in phase 1. Perspectives for phase 2, operating with the full capability of the device with the complete ITER-grade actively cooled lower divertor, are also described

    Ensaios de inovação no ensino médio

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    O objetivo deste trabalho é examinar alguns ensaios de inovação que vêm ocorrendo no ensino de nível médio e destacar elementos que possam contribuir para sua interpretação bem como para a formulação de políticas de apoio e de orientação às escolas. Em um primeiro momento, examinam-se a centralidade do ensino médio no conjunto das reformas educativas, o direcionamento destas reformas no contexto da mudança do papel do Estado e as questões relativas à formação geral e à formação profissional. A segunda parte deste ensaio é dedicada ao exame de alguns conceitos de reforma e de inovação e à descrição e análise de relatos de experiências e ensaios de inovação realizados por escolas de nível médio. São relatos apresentados por escolas públicas estaduais que participaram da primeira fase do Programa de Expansão e Melhoria do Ensino Médio da Secretaria de Estado da Educação de São Paulo¹, entre os anos 2000 e 2001. Os relatos apresentados, com exceção daqueles referentes à gestão da aplicação dos recursos financeiros distribuídos pelo programa, referem-se a ensaios de inovação realizados pelas escolas antes de sua vinculação a ele.<br>This article aims to examine some of the experiences implemented at the mid level and to highlight elements that can contribute to their interpretation as well as the formulation of policies to support and guide the schools. First, the centrality of mid level education to the body of educational reforms is examined, the nature of these reforms in the context of the changing role of the State and issues referring to training in general and of professionals. The second part is dedicated to an examination of some concepts of reform and of innovation and a description and analysis of reports of experiences and trails of innovations realized by mid level schools. These are reports presented by state public schools which participated in the first phase of the Program to Improve and Expand Mid level Teaching of the São Paulo State Department of Education in 2000 and 2001. The reports presented, with the exception of those that refer to managing the application of financial resources distributed by the program, refer to trials of innovations realized by schools prior to their connection to the program
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