1,080 research outputs found
Robust Lagrange multiplier test with forward search simulation envelopes
No full textThe Lagrange multiplier test, often adopted to detect heteroscedasticity, suffers from severe size distortion and has low power. An existing robust test based on a forward search algorithm has shown better performance than many existing robust methods. Nevertheless, such a forward robust test
relies on con ̄dence bands based on the Student's-t distribution which hold only approximately. The robust forward weighted Lagrange multiplier test can be improved through extensive simulation of forward search con ̄dence bands, which are set up under the hypothesis of no outlier in the data
High-Level Synthesis Developments in the Context of European Space Technology Research (Invited Talk)
No full textEuropean efforts to boost competitiveness in the space services sector promote the research and development of advanced software and hardware solutions. The EU-funded HERMES project contributes to the effort by qualifying radiation-hardened, high-performance programmable microprocessors and developing a software ecosystem that facilitates the deployment of complex applications on such platforms. The main objectives of the project include reaching a technology readiness level of 6 (i.e., validated and demonstrated in relevant environment) for the rad-hard NG-ULTRA FPGA with its ceramic hermetic package CGA 1752, developed within projects of the European Space Agency, French National Centre for Space Studies and the European Union. An equally important share of the project is dedicated to the development and validation of tools that support multicore software programming and FPGA acceleration. The HERMES project selected the Bambu High-Level Synthesis tool to integrate capabilities to translate C/C++ code into Verilog/VHDL in its development ecosystem. In HERMES, Bambu has been and will be extended to support new FPGA targets, architectural models, model-based design, and input applications. The increased performance offered by FPGAs is thus made available also to software developers who do not have hardware design expertise
Contabilità macroeconomica e dimensione di impresa nell'industria tessile del distretto di Prato}
No full textIl lavoro concerne l'analisi dell'industria tessile di Prato per mezzo di indicatori economici e strumenti statistici quali il modello Mover Staye
High-Level Synthesis of the OpenMP runtime to improve the generation of parallel accelerators
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Large-signal device simulation in time- and frequency-domain: a comparison
No full textThe aim of this paper is to compare the most common time- and frequency-domain numerical techniques for the determination of the steady-state solution in the physics-based simulation of a semiconductor device driven by a time-periodic generator. The shooting and harmonic balance (HB) techniques are applied to the solution of the discretized drift-diffusion device model coupled to the external circuit embedding the semiconductor device, thus providing a fully nonlinear mixed mode simulation. The comparison highlights the strong and weak points of the two approaches, basically showing that the time-domain solution is more robust with respect to the initial condition, while the HB solution provides a more rapid convergence once the initial datum is close enough to the solution itsel
Calcite-Bearing Foiditic Lavas Of Colli Albani Volcanic District (Central Italy): New Petrographic And Geochemical Data.
No full text8. The Colli Albani volcanic district, near the city of Rome, represents one of the most peculiar volcanic districts on the Earth because of its liquid line of descent characterized by differentiated K-foiditic magmas. Field, geochemical and experimental studies have demonstrated that such a differentiation trend is mainly due to magma-carbonate interaction. One impressive evidence of this process is the occurrence of magmatic calcite in the lava flows groundmass. Despite many studies have investigated petrological and geochemical features of the Colli Albani magmas, several questions remain unanswered. One of these concerns the 87Sr/86Sr and 143Nd/144Nd ratio trends observed in products representative of the whole Colli Albani eruptive history. Another open question concerns the role of fluorine in the magmatic system and its effects on phase relationships. Starting from these questions we have started a petrographic and geochemical study on lava flows emplaced during the whole Colli Albani activity with the aim to better understand the processes of genesis and evolution of magmas. Here we present preliminary petrographic and geochemical data on those lava flows. In particular, the oldest lava flow studied (≥560 ka) is a lithic fragment in the Trigoria Tor de’ Cenci pyroclastic flow that has the highest 87Sr/86Sr ratio (0.711196) among all those studied. Young lava flows present low 87Sr/86Sr (0.709879) and high 143Nd/144Nd ratios and some of these are characterized by the occurrence of strontian fluoro-magnesiohastingsite in the groundmass and lack of calcite, probably linked to changes in fluorine and CO2 activity. We interpret the variations in fluorine activity and isotope values as due to changes in the metasomatic component (i.e. phlogopite) of the mantle source
A note on the author citation and typification of Cineraria aurantiaca Hoppe (Tephroseris integrifolia subsp. aurantiaca; Asteraceae)
No full textBartolucci, Fabrizio, Villani, Mariacristina, Galasso, Gabriele (2021): A note on the author citation and typification of Cineraria aurantiaca Hoppe (Tephroseris integrifolia subsp. aurantiaca; Asteraceae). Phytotaxa 512 (4): 297-299, DOI: 10.11646/phytotaxa.512.4.6, URL: http://dx.doi.org/10.11646/phytotaxa.512.4.
White Pumice vs. Black-Grey Scoria in the Tufo Giallo della Via Tiberina (Sabatini Volcanic District, Roman Province): Evidence of Temperature- and H2O-Zoning in Phonolitic Magma Chambers
No full textChanges in colour and texture of the juvenile component are often observed in the deposits of explosive eruptions. The transition from white aphyric juvenile clasts (white pumice) towards highly crystalline ones (black-grey scoria) is usually explained by means of compositional layering of the magma chamber or by syn-eruptive magma mixing. However, these textural variations may even occur without accompanying compositional changes, as is the case of the Tufo Giallo della Via Tiberina (Roman Province, central Italy). This pyroclastic succession comprises two eruptive units, emplaced at ca. 561 and 548 ka, during the early explosive activity of the Sabatini Volcanic District. White pumice and black-grey scoria, occurring respectively in the lower and intermediate-upper portions of each eruptive unit, are characterized by remarkably different textures, in spite of common phonolitic bulk compositions: white pumice is subaphiric (P.I.60%, with dominant leucite phenocrysts) and poorly vesicular. Phase relationships (MELTS simulations) and cpx-liquid geothermometry yield temperature estimates at 890-920°C and 920-940°C, respectively for white pumice and black-grey scoria feeder-magmas, and P=150-200 MPa. The diffuse occurrence of leucite phenocrysts in black-grey scoria records crystallization at initially H2O-undersaturated conditions, while the vitrophyric texture of white pumice indicates H2O-saturated conditions. In our model, the pre-eruptive H2O over-saturation was achieved by water diffusion from the cooler and highly crystallized, peripheral portions (black-grey scoria) toward the inner, subaphyric, portions (white pumice) of the magma chambers, as a consequence of radial H2O concentration gradients. The withdrawal of the white pumice feeder-magma in the early eruptive stages caused decompression and extensive crystallization in the peripheral magma portions, triggering fragmentation and eruption of the black-grey scoria magma in the late eruptive stages
Time-dependent geochemistry of volcanic products from Colli Albani (Central Italy): clues to source and evolution of ultrapotassic magmas
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