3,870 research outputs found
Electron beam transfer line design for plasma driven Free Electron Lasers
Plasma driven particle accelerators represent the future of compact
accelerating machines and Free Electron Lasers are going to benefit from these
new technologies. One of the main issue of this new approach to FEL machines is
the design of the transfer line needed to match of the electron-beam with the
magnetic undulators. Despite the reduction of the chromaticity of plasma beams
is one of the main goals, the target of this line is to be effective even in
cases of beams with a considerable value of chromaticity. The method here
explained is based on the code GIOTTO [1] that works using a homemade genetic
algorithm and that is capable of finding optimal matching line layouts directly
using a full 3D tracking code.Comment: 9 Pages, 4 Figures. A related poster was presented at EAAC 201
Behuria lumiarensis (Melastomataceae), a new species on a mountaintop of the brazilian Atlantic Forest
We describe and illustrate Behuria lumiarensis, a new species from the state of Rio de Janeiro, Brazil. It has been collected only once in montane vegetation in the Municipality of Nova Friburgo. The new species can be recognized by the combination of leaf blades with adaxial surface covered with sessile glands and abaxial surface moderately covered with stalked glands only on the veins, hypanthium sparsely covered with stalked glands, a large calyx tube with narrow sepals that are not apiculate in the apex, small petals, and glabrous ovary apex.3052111117CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQCOORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPES457510/2014-5; 306852/2013-6Sem informaçã
Following glaziou’s footsteps: rediscovery and updated description of three species of behuria cham. (melastomataceae) from the Atlantic forest (Brazil)
This study was carried out in the state of Rio de Janeiro and led to the rediscovery of three endemic and threatened species of Behuria (Melastomataceae). The type specimens for these species were collected by the French botanist A.F.M. Glaziou. Behuria corymbosa and Behuria glazioviana were collected for the last time 127 years ago by him, in 1889. Behuria mourae was collected twice after the type; the last collection dates from about 72 years ago. In order to find the exact localities where Glaziou collected these three species we studied the labels of the type specimens, Glaziou’s notebooks and letters, looking for tracks that would lead us to places that he visited. We also consulted documents from a local library and gathered information from local people. Here we present updated descriptions, comments, photos and conservation assessments for each species.3023229240CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQCOORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPES306852/2013-6Sem informaçã
Three New Species Of Bertolonia (melastomataceae) From Espírito Santo, Brazil
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)We describe and illustrate three new species of Bertolonia, all endemic to the state of Espírito Santo, Brazil. Bertolonia duasbocaensis and B. macrocalyx occur close to each other, in the municipalities of Cariacica and Viana. Bertolonia ruschiana has a wider distribution, occurring in the municipalities of Santa Leopoldina, Santa Maria de Jetibá and Santa Teresa. The first two species are classified as critically endangered (CR), and the latter as endangered (EN). We also present an identification key for the species of Bertolonia that occur in Espírito Santo. © 2016 Bacci et al.201612CAPES, Coordenação de Aperfeiçoamento de Pessoal de Nível Superior306852/2013-6, CNPq, Conselho Nacional de Desenvolvimento Científico e Tecnológico310717/2015-9, CNPq, Conselho Nacional de Desenvolvimento Científico e TecnológicoDEB-1343612, NSF, National Science FoundationDEB-818399, NSF, National Science FoundationCoordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq
Study of RPC gas mixtures for the ARGO-YBJ experiment
The ARGO-YBJ experiment consists of a RPC carpet to be operated at the
Yangbajing laboratory (Tibet, P.R. China), 4300 m a.s.l., and devoted to the
detection of showers initiated by photon primaries in the energy range 100 GeV
- 20 TeV. The measurement technique, namely the timing on the shower front with
a few tens of particles, requires RPC operation with 1 ns time resolution, low
strip multiplicity, high efficiency and low single counting rate. We have
tested RPCs with many gas mixtures, at sea level, in order to optimize these
parameters. The results of this study are reported.Comment: 6 pages, 3 figures. To be published in Nucl. Instr. Meth. A, talk
given at the "5th International Workshop on RPCs and Related Detectors", Bari
(Italy) 199
Robustness evaluation of different controllers in the presence of flow rate variations
This paper proposes a direct approach to evaluate achievable robustness to flow rate variations of different controllers (PID and advanced algorithms), for typical process dynamics (First Order Plus Time Delay with different time delay/lag ratio), able to represent very common heat exchange equipment. Starting from comparable nominal performance, the effect of flow rate variations on process parameters and consequently on achievable performance is analyzed in simulation up to the onset of marginal stability conditions. Flow rate variations act as “structured” uncertainty on parameters and the proposed procedure is able to indicate maximum allowable variations in a more realistic and efficient way, avoiding the conservatism implicit in most of analytical design techniques available in the literature. The proposed technique evaluates in a straightforward way the Maximum Allowed Changes (MAC) in flow rate. As inverse proportionality between flow rate and process parameters is present, also the efficacy of adopting equal percentage (EP) valves, which allow a local compensation of process gain nonlinearity, is investigated
EuPRAXIA@SPARC_LAB: the high-brightness RF photo-injector layout proposal
At EuPRAXIA@SPARC_LAB, the unique combination of an advanced high-brightness
RF injector and a plasma-based accelerator will drive a new multi-disciplinary
user-facility. The facility, that is currently under study at INFN-LNF
Laboratories (Frascati, Italy) in synergy with the EuPRAXIA collaboration, will
operate the plasma-based accelerator in the external injection configuration.
Since in this configuration the stability and reproducibility of the
acceleration process in the plasma stage is strongly influenced by the
RF-generated electron beam, the main challenge for the RF injector design is
related to generating and handling high quality electron beams. In the last
decades of R&D activity, the crucial role of high-brightness RF photo-injectors
in the fields of radiation generation and advanced acceleration schemes has
been largely established, making them effective candidates to drive
plasma-based accelerators as pilots for user facilities. An RF injector
consisting in a high-brightness S-band photo-injector followed by an advanced
X-band linac has been proposed for the EuPRAXIA@SPARC_LAB project. The electron
beam dynamics in the photo-injector has been explored by means of simulations,
resulting in high-brightness, ultra-short bunches with up to 3 kA peak current
at the entrance of the advanced X-band linac booster. The EuPRAXIA@SPARC_LAB
high-brightness photo-injector is described here together with performance
optimisation and sensitivity studies aiming to actual check the robustness and
reliability of the desired working point.Comment: 5 pages,5 figures, EAAC201
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