Página 6 dos resultados de 1996 itens digitais encontrados em 0.007 segundos

Interpreting variability in global SST data using independent component analysis and principal component analysis

Westra, S.; Brown, C.; Lall, U.; Koch, I.; Sharma, A.
Fonte: John Wiley & Sons Ltd Publicador: John Wiley & Sons Ltd
Tipo: Artigo de Revista Científica
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Component extraction techniques are used widely in the analysis and interpretation of high-dimensional climate datasets such as global sea surface temperatures (SSTs). Principal component analysis (PCA), a frequently used component extraction technique, provides an orthogonal representation of the multivariate dataset and maximizes the variance explained by successive components. A disadvantage of PCA, however, is that the interpretability of the second and higher components may be limited. For this reason, a Varimax rotation is often applied to the PCA solution to enhance the interpretability of the components by maximizing a simple structure. An alternative rotational approach is known as independent component analysis (ICA), which finds a set of underlying ‘source signals’ which drive the multivariate ‘mixed’ dataset. Here we compare the capacity of PCA, the Varimax rotation and ICA in explaining climate variability present in globally distributed SST anomaly (SSTA) data. We find that phenomena which are global in extent, such as the global warming trend and the El Niño-Southern Oscillation (ENSO), are well represented using PCA. In contrast, the Varimax rotation provides distinct advantages in interpreting more localized phenomena such as variability in the tropical Atlantic. Finally...

Not Just a Matter of Time: Field Differences and the Shaping of Electronic Media

Kling, Rob; McKim, Geoffrey
Fonte: Rob Kling Center for Social Informatics Publicador: Rob Kling Center for Social Informatics
Tipo: Trabalho em Andamento Formato: 10176 bytes; 95696 bytes; image/jpeg; text/html
EN_US
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The shift towards the use of electronic media in scholarly communication appears to be an inescapable imperative. However, these shifts are uneven, both with respect to field and with respect to the form of communication. Different scientific fields have developed and use distinctly different communicative forums, both in the paper and electronic arenas, and these forums play different communicative roles within the field. One common claim is that we are in the early stages of an electronic revolution, that it is only a matter of time before other fields catch up with the early adopters, and that all fields converge on a stable set of electronic forums. A social shaping of technology (SST) perspective helps us to identify important social forces – centered around disciplinary constructions of trust and of legitimate communication – that pull against convergence. This analysis concludes that communicative plurality and communicative heterogeneity are durable features of the scholarly landscape, and that we are likely to see field differences in the use of and meaning ascribed to communications forums persist, even as overall use of electronic communications technologies both in science and in society as a whole increases.; Indiana University

Aplicación del sistema de gestión de la seguridad y salud en el trabajo (sg-sst) en la empresa Materiales Art S.A.S

Tipo: Bachelor Thesis; Pasantía Formato: PDF
SPA
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El presente proyecto tiene como fin otogarle a la empresa MATERIALES ART S.A.S, el desarrollo de unas actividades especificas,que le ayudarán a realizar la aplicación de un sistema de seguridad y salud en el trabajo SG-SST, por medio de la elaboracion de los subprogramas de higiene y seguridad industrial y medicina preventiva, lo cual ayudara a minimizar y controlar los riesgos en la empresa. El proyecto consistió especialmente en tomar cada una de las actividades del subprograma de higiene y seguriad industrial , verificar si se está cumpliendo o que hacer para cumplirlo, tambien se realizó el mismo procedimiento para el subprograma de medicina preventiva. El proyecto finaliza con la socializacion del sistema de seguriad y salud en el trabajo, en donde se les explica a los trabajadores las nuevas medidas que se tomaran para su propio bienestar

Diagnóstico de la aplicación de procesos estandarizados de Gestión en Salud Ocupacional en las Instituciones de educación superior y propuesta de modelo para la construcción del SG - SST

Quintero Sastre, Angélica
Tipo: bachelorThesis; Trabajo de grado Formato: pdf; 132 p.; Electrónico
SPA
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The role of the SST-thermocline relationship in Indian Ocean Dipole skewness and its response to global warming

Ng, Benjamin; Cai, Wenju; Walsh, Kevin
Fonte: Nature Publishing Group Publicador: Nature Publishing Group
Tipo: Artigo de Revista Científica
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A positive Indian Ocean Dipole (IOD) tends to have stronger cold sea surface temperature anomalies (SSTAs) over the eastern Indian Ocean with greater impacts than warm SSTAs that occur during its negative phase. Two feedbacks have been suggested as the cause of positive IOD skewness, a positive Bjerknes feedback and a negative SST-cloud-radiation (SCR) feedback, but their relative importance is debated. Using inter-model statistics, we show that the most important process for IOD skewness is an asymmetry in the thermocline feedback, whereby SSTAs respond to thermocline depth anomalies more strongly during the positive phase than negative phase. This asymmetric thermocline feedback drives IOD skewness despite positive IODs receiving greater damping from the SCR feedback. In response to global warming, although the thermocline feedback strengthens, its asymmetry between positive and negative IODs weakens. This behaviour change explains the reduction in IOD skewness that many models display under global warming.

Extremos de temperaturas en Argentina: cambios observados en la variabilidad espacio-temporal y su relación con otras características del sistema climático; Temperature extremes in Argentina: observed changes in the spatial and temporal variability and the relationship with other characteristics of the climatic system

Barrucand, Mariana Graciela
Tipo: info:eu-repo/semantics/doctoralThesis; tesis doctoral; info:eu-repo/semantics/publishedVersion Formato: application/pdf
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El presente trabajo de tesis estudia la variabilidad en la frecuencia de temperaturas extremas en la Argentina durante el período 1959-2003 Se analizan tres aspectos específicos: la homogeneidad espacial que tienen los extremos de temperatura en Argentina, la variabilidad temporal de los mismos y la relación con otras características del sistema climático. El análisis de homogeneidad espacial mostró algunas diferencias respecto al tipo de extremo analizado y permitió la selección de estaciones de referencia para estudios ulteriores. El análisis de variabilidad temporal mostró tendencias significativas negativas (positivas) en la frecuencia de noches frías (cálidas) entre los meses de octubre y marzo, siendo estos últimos los de mayores cambios. Esto indica una extensión de las condiciones cálidas desde los comienzos de la primavera hasta el comienzo del otoño. En los meses de época fría (abril a septiembre) se destaca un aumento en la frecuencia de noches cálidas, excepto en julio que presenta una tendencia negativa en el centro-este del país. En términos generales, se observa una disminución en la frecuencia de días cálidos en gran parte del año. Las excepciones están dadas para los meses de agosto y octubre. Los resultados encontrados son congruentes con una disminución en la amplitud térmica observada en todo el país durante todo el año...

South Tasman Sea alkenone palaeothermometry over the last four glacial/interglacial cycles

Pelejero, Carles; Calvo, Eva; Barrows, Timothy; Logan, Graham A; De Deckker, Patrick
Tipo: Artigo de Revista Científica
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Alkenone palaeothermometry has demonstrated a wide spatial and temporal applicability for the reconstruction of sea-surface temperatures (SST). Some oceanic realms, however, remain poorly studied. We document U37K' index data for two sediment cores retrie

Using muon rings for the optical throughput calibration of the SST-1M prototype for the Cherenkov Telescope Array

Toscano, S.; Prandini, E.; Bilnik, W.; Błocki, J.; Bogacz, L.; Bulik, T.; Cadoux, F.; Christov, A.; Curyło, M.; della Volpe, D.; Dyrda, M.; Favre, Y.; Frankowski, A.; Grudnik, Ł.; Grudzińska, M.; Heller, M.; Idźkowski, B.; Jamrozy, M.; Janiak, M.; Ka
Tipo: Artigo de Revista Científica
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Imaging Atmospheric Cherenkov Telescopes (IACTs) are ground-based instruments devoted to the study of very high energy gamma-rays coming from space. The detection technique consists of observing images created by the Cherenkov light emitted when gamma rays, or more generally cosmic rays, propagate through the atmosphere. While in the case of protons or gamma-rays the images present a filled and more or less elongated shape, energetic muons penetrating the atmosphere are visualised as characteristic circular rings or arcs. A relatively simple analysis of the ring images allows the reconstruction of all the relevant parameters of the detected muons, such as the energy, the impact parameter, and the incoming direction, with the final aim to use them to calibrate the total optical throughput of the given IACT telescope. We present the results of preliminary studies on the use of images created by muons as optical throughput calibrators of the single mirror small size telescope prototype SST-1M proposed for the Cherenkov Telescope Array.; Comment: In Proceedings of the 34th International Cosmic Ray Conference (ICRC2015), The Hague, The Netherlands. All CTA contributions at arXiv:1508.05894

First simultaneous SST/CRISP and IRIS observations of a small-scale quiet Sun vortex

Park, S. -H.; Tsiropoula, G.; Kontogiannis, I.; Tziotziou, K.; Scullion, E.; Doyle, J. G.
Tipo: Artigo de Revista Científica
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Ubiquitous small-scale vortices have recently been found in the lower atmosphere of the quiet Sun in state-of-the-art solar observations and in numerical simulations. We investigate the characteristics and temporal evolution of a granular-scale vortex and its associated upflows through the photosphere and chromosphere of a quiet Sun internetwork region. We analyzed high spatial and temporal resolution ground- and spaced-based observations of a quiet Sun region. The observations consist of high-cadence time series of wideband and narrowband images of both H-alpha 6563 A and Ca II 8542 A lines obtained with the CRisp Imaging SpectroPolarimeter (CRISP) instrument at the Swedish 1-m Solar Telescope (SST), as well as ultraviolet imaging and spectral data simultaneously obtained by the Interface Region Imaging Spectrograph (IRIS). A small-scale vortex is observed for the first time simultaneously in H-alpha, Ca II 8542 A, and Mg II k lines. During the evolution of the vortex, H-alpha narrowband images at -0.77 A and Ca II 8542 A narrowband images at -0.5 A, and their corresponding Doppler Signal maps, clearly show consecutive high-speed upflow events in the vortex region. These high-speed upflows with a size of 0.5-1 Mm appear in the shape of spiral arms and exhibit two distinctive apparent motions in the plane of sky for a few minutes: (1) a swirling motion with an average speed of 13 km/s and (2) an expanding motion at a rate of 4-6 km/s. Furthermore...

The ASTRI SST-2M Prototype: Structure and Mirror

Canestrari, Rodolfo; Catalano, Osvaldo; Fiorini, Mauro; Giro, Enrico; La Palombara, Nicola; Pareschi, Giovanni; Stringhetti, Luca; Tosti, Gino; Vercellone, Stefano; Collaboration, for the ASTRI; Martelli, Francesco; Parodi, Giancarlo; Rossettini, Pierfran
Tipo: Artigo de Revista Científica
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The next generation of IACT (Imaging Atmospheric Cherenkov Telescope) will explore the uppermost end of the VHE (Very High Energy) domain up to about few hundreds of TeV with unprecedented sensibility, angular resolution and imaging quality. To this end, INAF (Italian National Institute of Astrophysics) is currently developing a scientific and technological telescope prototype for the implementation of the CTA (Cherenkov Telescope Array) observatory. ASTRI (Astrofisica con Specchi a Tecnologia Replicante Italiana) foresees the full design, development, installation and calibration of a Small Size 4 meter class Telescope. The telescope, named SST-2M, is based on an aplanatic, wide field, double reflection optical layout in a Schwarzschild-Couder configuration. In this paper we report about the technological solutions adopted for the telescope and for the mirrors. In particular the structural and electro-mechanical design of the telescope and the results on the optical performance derived after the development of a prototype of the segments that will be assembled to form the primary mirror.; Comment: In Proceedings of the 33rd International Cosmic Ray Conference (ICRC2013), Rio de Janeiro (Brazil). All ASTRI contributions at arXiv:1307.4639

Expected performance of the ASTRI-SST-2M telescope prototype

Bigongiari, C.; Di Pierro, F.; Morello, C.; Stamerra, A.; Vallania, P.; Agnetta, G.; Antonelli, L. A.; Bastieri, D.; Bellassai, G.; Belluso, M.; Billotta, S.; Biondo, B.; Bonanno, G.; Bonnoli, G.; Bruno, P.; Bulgarelli, A.; Canestrari, R.; Capalbi, M.; Ca
Tipo: Artigo de Revista Científica
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ASTRI (Astrofisica con Specchi a Tecnologia Replicante Italiana) is an Italian flagship project pursued by INAF (Istituto Nazionale di Astrofisica) strictly linked to the development of the Cherenkov Telescope Array, CTA. Primary goal of the ASTRI program is the design and production of an end-to-end prototype of a Small Size Telescope for the CTA sub-array devoted to the highest gamma-ray energy region. The prototype, named ASTRI SST-2M, will be tested on field in Italy during 2014. This telescope will be the first Cherenkov telescope adopting the double reflection layout in a Schwarzschild-Couder configuration with a tessellated primary mirror and a monolithic secondary mirror. The collected light will be focused on a compact and light-weight camera based on silicon photo-multipliers covering a 9.6 deg full field of view. Detailed Monte Carlo simulations have been performed to estimate the performance of the planned telescope. The results regarding its energy threshold, sensitivity and angular resolution are shown and discussed.; Comment: In Proceedings of the 33rd International Cosmic Ray Conference (ICRC2013), Rio de Janeiro (Brazil). All CTA contributions at arXiv:1307.2232

Calibration of the ASTRI SST-2M Prototype using Muon Ring Images

Strazzeri, Elisabetta; Bonnoli, Giacomo; Lombardi, Saverio; Maccarone, Maria Concetta; Mineo, Teresa; Collaboration, for the ASTRI
Tipo: Artigo de Revista Científica
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The study of ring images generated from high-energy muons is a very useful tool for the performance monitoring and calibration of any Imaging Atmosphere Cherenkov Telescope. Isolated muons travelling towards the telescope light collector system produce characteristic Cherenkov ring images in the focal plane camera. Since the geometry and the distribution of light deployed onto the camera can be easily reconstructed analytically for a muon of given energy and direction, muon rings are a powerful tool for monitoring the behaviour of crucial properties of an imaging telescope such as the point-spread-function and the overall light collection efficiency. In this contribution we present the possibility of using the analysis of muon ring images as calibrator for the ASTRI SST-2M prototype point spread function.; Comment: In Proceedings of the 33rd International Cosmic Ray Conference (ICRC2013), Rio de Janeiro (Brazil). All ASTRI contributions at arXiv:1307.4639

Ellerman bombs at high resolution III. Simultaneous observations with IRIS and SST

Vissers, Gregal J. M.; van der Voort, Luc H. M. Rouppe; Rutten, Robert J.; Carlsson, Mats; De Pontieu, Bart
Tipo: Artigo de Revista Científica
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Ellerman bombs are transient brightenings of the extended wings of the solar Balmer lines in emerging active regions. We describe their properties in the ultraviolet lines sampled by the Interface Region Imaging Spectrograph (IRIS), using simultaneous imaging spectroscopy in H$\alpha$ with the Swedish 1-m Solar Telescope (SST) and ultraviolet images from the Solar Dynamics Observatory for Ellerman bomb detection and identification. We select multiple co-observed Ellerman bombs for detailed analysis. The IRIS spectra strengthen the view that Ellerman bombs mark reconnection between bipolar kilogauss fluxtubes with the reconnection and the resulting bi-directional jet located within the solar photosphere and shielded by overlying chromospheric fibrils in the cores of strong lines. The spectra suggest that the reconnecting photospheric gas underneath is heated sufficiently to momentarily reach stages of ionization normally assigned to the transition region and the corona. We also analyze similar outburst phenomena that we classify as small flaring arch filaments and ascribe to higher-located reconnection. They have different morphology and produce hot arches in million-Kelvin diagnostics.; Comment: Accepted for publication in the Astrophysical Journal. 19 pages...

Performance of the Mechanical Structure of the SST-2M GCT Proposed for the Cherenkov Telescope Array

Dournaux, Jean-Laurent; Huet, Jean-Michel; Dumas, Delphine; Amans, Jean-Philippe; Fasola, Gilles; Laporte, Philippe; Bousquet, Jean-Jacques; Sol, Hélène
Tipo: Artigo de Revista Científica
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The Cherenkov Telescope Array (CTA) consortium aims to create the next generation Very High Energy gamma-ray observatory. It will be devoted to the observation of gamma rays over a wide band of energy, from 20 GeV to 300 TeV. Three different classes, Large, Medium and Small Size Telescopes, are foreseen to cover the low, intermediate and high energy regions, respectively. The energy range of the Small Size Telescopes (SSTs) extends from 1 TeV to 300 TeV. Among them, the Gamma-ray Cherenkov Telescope (GCT), a telescope based on a Schwarzschild-Couder dual-mirror optical design, is one of the prototypes under construction proposed for the SST sub-array of CTA. This contribution focuses on the mechanical structure of GCT. It reports on last progress on the mechanical design and discusses this in the context of CTA specifications. Recent advances in the assembly and installation of the opto-mechanical prototype of GCT on the French site of the Paris Observatory are also described.; Comment: In Proceedings of the 34th International Cosmic Ray Conference (ICRC2015), The Hague, The Netherlands. All CTA contributions at arXiv:1508.05894

The SST-1M camera for the Cherenkov Telescope Array

Schioppa, E. J.; Cadoux, F.; Christov, A.; della Volpe, D.; Favre, Y.; Heller, M.; Montaruli, T.; Porcelli, A.; Rameez, M.; Pujadas, I. Troyano; Bilnik, W.; Blocki, J.; Bogacz, L.; Bulik, T.; Curylo, M.; Dyrda, M.; Frankowski, A.; Grudniki, L.; Grudzinska
Tipo: Artigo de Revista Científica
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The prototype camera of the single-mirror Small Size Telescopes (SST-1M) proposed for the Cherenkov Telescope Array (CTA) project has been designed to be very compact and to deliver high performance over thirty years of operation. The camera is composed of an hexagonal photo-detection plane made of custom designed large area hexagonal silicon photomultipliers and a high throughput, highly configurable, fully digital readout and trigger system (DigiCam). The camera will be installed on the telescope structure at the H. Niewodnicza{\'n}ski institute of Nuclear Physics in Krakow in fall 2015. In this contribution, we review the steps that led to the development of the innovative photo-detection plane and readout electronics, and we describe the test and calibration strategy adopted.; Comment: In Proceedings of the 34th International Cosmic Ray Conference (ICRC2015), The Hague, The Netherlands. All CTA contributions at arXiv:1508.05894; Full consortium author list at http://cta-observatory.org

Development of the optical system for the SST-1M telescope of the Cherenkov Telescope Array observatory

Seweryn, K.; Bilnik, W.; Błocki, J.; Bogacz, L.; Bulik, T.; Cadoux, F.; Christov, A.; Chruślińska, M.; Curyło, M.; della Volpe, D.; Dyrda, M.; Favre, Y.; Frankowski, A.; Grudnik, Ł.; Grudzińska, M.; Heller, M.; Idźkowski, B.; Jamrozy, M.; Janiak, M
Tipo: Artigo de Revista Científica
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The prototype of a Davies-Cotton small size telescope (SST-1M) has been designed and developed by a consortium of Polish and Swiss institutions and proposed for the Cherenkov Telescope Array (CTA) observatory. The main purpose of the optical system is to focus the Cherenkov light emitted by extensive air showers in the atmosphere onto the focal plane detectors. The main component of the system is a dish consisting of 18 hexagonal mirrors with a total effective collection area of 6.47 m2 (including the shadowing and estimated mirror reflectivity). Such a solution was chosen taking into account the analysis of the Cherenkov light propagation and based on optical simulations. The proper curvature and stability of the dish is ensured by the mirror alignment system and the isostatic interface to the telescope structure. Here we present the design of the optical subsystem together with the performance measurements of its components.; Comment: In Proceedings of the 34th International Cosmic Ray Conference (ICRC2015), The Hague, The Netherlands. All CTA contributions at arXiv:1508.05894

Multivariate forecast of winter monsoon rainfall in India using SST anomaly as a predictor: Neurocomputing and statistical approaches

Tipo: Artigo de Revista Científica
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In this paper, the complexities in the relationship between rainfall and sea surface temperature (SST) anomalies during the winter monsoon (November-January) over India were evaluated statistically using scatter plot matrices and autocorrelation functions.Linear as well as polynomial trend equations were obtained and it was observed that the coefficient of determination for the linear trend was very low and it remained low even when polynomial trend of degree six was used. An exponential regression equation and an artificial neural network with extensive variable selection were generated to forecast the average winter monsoon rainfall of a given year using the rainfall amounts and the sea surface temperature anomalies in the winter monsoon months of the previous year as predictors. The regression coefficients for the multiple exponential regression equation were generated using Levenberg-Marquardt algorithm. The artificial neural network was generated in the form of a multiplayer perceptron with sigmoid non-linearity and genetic-algorithm based variable selection. Both of the predictive models were judged statistically using the Willmott index, percentage error of prediction, and prediction yields. The statistical assessment revealed the potential of artificial neural network over exponential regression.; Comment: 18 pages

Prototype of the SST-1M Telescope Structure for the Cherenkov Telescope Array

Niemiec, J.; Bilnik, W.; Błocki, J.; Bogacz, L.; Borkowski, J.; Bulik, T .; Cadoux, F.; Christov, A.; Curyło, M.; della Volpe, D.; Dyrda, M.; Favre, Y.; Frankowski, A.; Grudnik, Ł.; Grudzińska, M.; Heller, M.; Idźkowski, B.; Jamrozy, M.; Janiak, M.;
Tipo: Artigo de Revista Científica
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A single-mirror small-size (SST-1M) Davies-Cotton telescope with a dish diameter of 4 m has been built by a consortium of Polish and Swiss institutions as a prototype for one of the proposed small-size telescopes for the southern observatory of the Cherenkov Telescope Array (CTA). The design represents a very simple, reliable, and cheap solution. The mechanical structure prototype with its drive system is now being tested at the Institute of Nuclear Physics PAS in Krakow. Here we present the design of the prototype and results of the performance tests of the structure and the drive and control system.; Comment: In Proceedings of the 34th International Cosmic Ray Conference (ICRC2015), The Hague, The Netherlands. All CTA contributions at arXiv:1508.05894

The SST Multi-G-Sample/s Switched Capacitor Array Waveform Recorder with Flexible Trigger and Picosecond-Level Timing Accuracy

Kleinfelder, Stuart A.; Chiem, Edwin; Prakash, Tarun
Tipo: Artigo de Revista Científica