4,010 research outputs found
Three-dimensional inverse design of axial compressor stator blade using neural-networks and direct Navier-Stokes solver
No full textCHEMILUMINESCENCE MEASUREMENTS IN A MESO-SCALE COMBUSTOR FUELED WITH CH4/AIR AT 0.3 MPa
No full textIn this work chemiluminescence emission from the main radical species are measured in a meso-scale combustor. Global and two-dimensional analysis is performed in order to gain information on the combustion processes occurring in the non-premixed swirled combustor fuelled with CH4/air and working at 0.3 MPa. The investigation is carried out by changing the equivalence ratio in the range of the stability limits, keeping constant the total mass flow rate. The behavior of OH*, CH* and CH*/CH* chemiluminescence as a function of the equivalence ratio are discussed both for global and spatially-resolved measurements. The two-dimensional results evidence the significant role of mixing and turbulence with respect to the chemical kinetic mechanisms
Wave energy farm design in real wave climates: the Italian offshore
No full textThe work focuses on hydrodynamic interactions between heaving wave energy converters (WEC). Wave parks of four devices are simulated in the time domain by a hydrodynamic-electromagnetic model, coupled with a boundary element code for the estimation of hydrodynamic parameters. Different layouts (linear, square and rhombus), WEC separation distances (5, 10, 20 and 30 buoy diameters) and incident wave directions (30° apart) are considered to assess the effect of design parameters on array power production. Then, a site-specific design optimization is carried out for different Italian locations and some key insights on wave farm design in real wave climates are provided. The results show that the effect of wave interactions on energy absorption is not expected to be a main issue, as long as the devices are separated by at least 10 buoy diameters and that the layouts are oriented to achieve the maximum energy absorption for the prevailing wave direction
Efficiency and stability of a meso-scale combustor at 3 atm
No full textThe performances of a cylindrical meso-scale swirl combustor having a volume of about 254 mm3 and working at 3 atm have been experimentally investigated. The analysis has been carried out for different equivalence ratios. In these experimental conditions, information about stability and efficiency of the meso-combustor were derived. To this purpose Fourier Transform Infrared Spectroscopy measurements have been carried out at the exhaust of the combustor. The gas concentration results obtained with this analysis are then compared with measurements carried out with commercial gas analyzer
Spatial interactions among oscillating wave energy converters: Electricity production and power quality issues
No full textPoint absorbers, i.e. wave energy converters (WECs) whose characteristic dimensions are small with respect to the typical wavelength, are designed to be installed in arrays, in order to get a cost-effective power generation. Starting from a coupled hydrodynamic electromagnetic model of a heaving point absorber, this paper presents an in-depth analysis of the hydrodynamic interactions among devices in array. The final goal is to find out the configurations of a four WEC array, which maximize the energy absorption and the quality of the power output. At this aim, different topological layouts, distances among converters and incident wave directions are investigated. The results highlight that a proper design of the wave farms allows to significantly reduce power fluctuations without negative side effects on electricity production.</p
IMPROVEMENTS ON THE TEST MASS SUSPENSIONS OF THE VIRGO LASER INTERFEROMETER GRAVITATIONAL-WAVE DETECTOR
No full textA new approach for the test mass suspensions of the VIRGO interferometric antenna has been proposed to increase the sensitivity at low frequencies by the reduction of the effects of vertical noises on the test mass. The experimental results are presented and discussed
TEST OF AN INTERFEROMETRIC SAPPHIRE TRANSDUCER WITH THE SUPER ATTENUATOR OF THE VIRGO GRAVITATIONAL-WAVE ANTENNA
No full textAn interferometric sapphire transducer has been used to test the super attenuator of the VIRGO laser interferometer gravitational wave antenna project. A test was carried out to characterise the horizontal displacement of the attenuator. The test showed the performance of the super attenuator to the transducer noise floor of 5 x 10(-15) m/square-root Hz at 60 Hz
Dynamic model, parameter extraction, and analysis of two topologies of a tubular linear generator for seawave energy production
No full texthis paper presents a comparison among two types of linear generators for wave energy conversion: an inner-permanent-magnet-slotted-tubular-linear- generator (IPM-STLG) and an outer-permanent-magnet-slotless-tubular-linear- generator (OPM-STLG). The magnetic and electric quantities are extracted and evaluated using Finite Element Method Magnetics (FEMM) software and Matlab. These quantities include magnetic flux, cogging forces and end effects, inductances, currents, e.m.f., and power. In addition, a comparison of the two topologies and the different parameters has been performed. The aim of this work is to show a methodology to design Tubular linear generators for Sea Wave energy production, together with a comparison among different architectures
A contextualização no ensino de biologia: um estudo com professores de escolas da rede pública estadual do município de Criciúma-SC
No full textTese (doutorado) - Universidade Federal de Santa Catarina. Programa de Pós-Graduação em Educação Científica e Tecnológica.Este trabalho tem como objetivo geral "Investigar as contribuições do ensino de biologia na construção de um conhecimento que possibilite ao aluno e ao professor compreender e explorar a realidade em que vivem capacitando-os a transitar entre o conhecimento científico e as peculiaridades do mundo que os cerca". Procura analisar como os professores de Biologia de Criciúma - SC lidam com a contextualização do Ensino e discute como essa forma de Ensino é compreendida por eles. Para isso usamos uma metodologia de cunho qualitativo que acontece em três momentos: o primeiro se caracteriza por um levantamento de trabalhos sobre ensino de Biologia contextualizado apresentados em encontros científicos da área. No segundo momento, é aplicado um questionário a todos os professores de Biologia da Rede Estadual de Ensino de Criciúma - SC que estavam na ativa. A partir dele, foi selecionado um grupo de 10 professores que passam a configurar o terceiro momento caracterizado pela realização de uma entrevista semi-estruturada com esses professores. As analises apontam que os professores procuram trabalhar de modo contextualizado, contudo percebe-se uma preocupação maior com o aprendizado dos conteúdos escolares dos alunos em detrimento da realidade de seu contexto de vida. Os professores indicam que existem fatores como o tempo para preparar as aulas, o número reduzido de aulas, a falta de recursos nas escolas, desinteresse e a desmotivação dos alunos, que dificultam a realização de um ensino contextualizado. Os resultados deste estudo sugerem que, um dos fatores que contribui para as dificuldades encontradas pelos professores é o atual paradigma educacional, pois esse dificulta a percepção das relações que existem entre os elementos que compõe o nosso mundo e conseqüentemente a identificação e a compreensão do contexto. Como uma possibilidade para se enfrentar essa situação esta pesquisa indica a Abordagem Relacional como uma estratégia educacional, tanto na formação inicial, como continuada dos professores. The present study has as its general objective to investigate the contributions provided by the teaching of biology in construction of knowledge, which allows both the teacher and the student to understand and explore their reality. This process also enables the teacher and the student to shift between the scientific knowledge and the peculiarities of the world that surrounds them. Furthermore, this study analyses how Biology teachers in Criciúma - SC approach the contextualization of teaching and discusses the teachers' views regarding this issue. In order to conduct this investigation, a qualitative analysis was carried out in three distinct phases. Firstly, data were gathered from articles and studies on the teaching of contextualized biology, which were presented in scientific conferences. Secondly, a questionnaire was applied to all biology teachers who were working in public schools in Criciúma. Thirdly, a semi-structured interview was conducted with a group ten teachers that participated in the second phase of the study. The analyses show that despite the fact that teachers attempt to apply the contextualized teaching, there exists a greater concern with students learning the syllabus as opposed to contextualizing students' real life. Teachers indicate that factors such as time to plan classes, the limited number of classes, scarce resources at schools, and students' lack of motivation and interest might create difficulties to the application of contextualized teaching. The results of this study demonstrate that one of the factors that contribute to the difficulties encountered by teachers it is the present educational paradigm, which restrains the understanding of the relationships that exist between the elements that make our world, and consequently the identification and comprehension of its context. As a possibility to face this situation, this study suggests the relational approach as an educational strategy to be taught in biology undergraduate courses as well as in continuing education courses
Performance of a prototype of the microstrip gas chambers for the CMS experiment at LHC
No full textA set of microstrip gas chamber (MSGC) prototypes, developed for the barrel Tracking Detector of the CMS experiment at LHC, has been tested in a beam. The chambers were 10 cm long, with Pestov or diamond coated glass substrate. The results on the performance of the chambers are reported. The spatial uniformity of the chambers is also illustrated
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