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Search Results: 1 - 10 of 462069 matches for " Secchi A. "
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On the Structure of the Solar Photosphere
Secchi A.
Progress in Physics , 2011,
Abstract: Mary Posani (Department of French and Italian, The Ohio State University, Columbus, Ohio, 43221) and Eileen Reeves (Department of Comparative Literature, Princeton University, Princeton, New Jersey, 08544) provide a translation of Father Pietro Angelo Secchi’s classic work “Sulla Struttura della Fotosfera Solare” as it appeared in Bullettino Meteorologico dell’ Osservatorio del Collegio Romano, 30 November 1864, v.3(11), 1–3. Secchi’s paper was immediately translated into French by l’Abbe Franc ois ′ Moigno appearing on December 22nd, 1864 (Sur la structure de la photosph`ere du soleil. Les Mondes, 1864, v.6, 703–707). Moigno’s translation prompted signi cant interest in the nature of the Sun throughout Europe, with rapid claims of simultaneous discovery by Harve Faye (Faye H. ′ Sur la constitution physique du soleil — premiereparti. Les Mondes, v.7, 293–306) and others. In this article, Secchi reiterated that the photosphere was composed of solid corpuscles oating on the transparent atmosphere of the Sun. Secchi concluded that the body of the Sun was gaseous based on his visualization of solar granules or “willow leaves” described by Nasmyth (Nasmyth J. Onthe Structure of the Luminous Envelope of the Sun — In a letter to Joseph Sidebotham. Memoirs of the Literary and Philosophical Society of Manchester, 1862, 3rd Series, v.I, 407– 411). Secchi also referred to Magnus’ work on solid particles in the gaseous ame (Magnus G. Notiz ¨uber die Beschaenheit der Sonne. Poggendor’s Annalen der Physik und Chemie, 1864, v.121, 510–512; also in French Notice sur la constitution du soleil. Archives des science physique et naturelles (Gen`eve), 1864, v.20, 171–175). The works by Sechhi, Nasmyth, Magnus, and Faye would dominate astrophysical thought for the next 50 years.
On the Theory of Sunspots Proposed by Signor Kirchoff
Secchi A.
Progress in Physics , 2011,
Abstract: Eileen Reeves (Department of Comparative Literature, Princeton University, Princeton, New Jersey, 08544) and Mary Posani (Department of French and Italian, The Ohio State University, Columbus, Ohio, 43221) provide a translation of Father Pietro Angelo Secchi’s classic work “Secchi A. Sulla Teoria Delle Macchie Solari: Proposta dal sig. Kircho ” as it appeared in Bullettino Meteorologico dell’ Osservatorio del Collegio Romano, 31 January 1864, v.3(4), 1– 4. This was the rst treatise to propose a particulate photosphere oating on the gaseous body of the Sun. The idea would dominateastrophysical thought for the next 50 years. Secchi appears to have drafted the article, as a response to Gustav Kirchho’s proposal, echoing early Galilean ideas, that sunspots represented clouds which oated above the photosphere. Other than presenting a newsolar model, noteworthy aspects of this work include Secchi’s appropriate insistence that materials do not emit the same light at the same temperature and his gentle rebuke of Kirchho relative to commenting on questions of astronomy.
A note on coupled nonlinear Schr?dinger systems under the effect of general nonlinearities
A. Pomponio,S. Secchi
Mathematics , 2009,
Abstract: We prove the existence of non-trivial solutions to a system of coupled, nonlinear, Schroedinger equations with general nonlinearity.
Global bifurcation of homoclinic solutions of hamiltonian systems
S. Secchi,C. A. Stuart
Mathematics , 2002,
Abstract: We provide global bifurcation results for a class of nonlinear hamiltonian systems
Multiplicity results for some nonlinear Schroedinger equations with potentials
A. Ambrosetti,A. Malchiodi,S. Secchi
Mathematics , 2000, DOI: 10.1007/s002050100152
Abstract: We prove some multiplicity results for a nonlinear equation of Schroedinger type with potential functions
Dynamic optimization of a FCC converter unit: numerical analysis
Almeida Nt, E.;Secchi, A. R.;
Brazilian Journal of Chemical Engineering , 2011, DOI: 10.1590/S0104-66322011000100014
Abstract: fluidized-bed catalytic cracking (fcc) is a process subject to frequent variations in the operating conditions (including feed quality and feed rate). the production objectives usually are the maximization of lpg and gasoline production. this fact makes the fcc converter unit an excellent opportunity for real-time optimization. the present work aims to apply a dynamic optimization in an industrial fcc converter unit, using a mechanistic dynamic model, and to carry out a numerical analysis of the solution procedure. a simultaneous approach was used to discretize the system of differential-algebraic equations and the resulting large-scale nlp problem was solved using the ipopt solver. this study also does a short comparison between the results obtained by a potential dynamic real-time optimization (drto) against a possible steady-state real-time optimization (rto) application. the results demonstrate that the application of dynamic real-time optimization of a fcc converter unit can bring significant benefits in production.
High-order finite volume method for solving viscoelastic fluid lows
Muniz, A. R.;Secchi, A. R.;Cardozo, N. S. M.;
Brazilian Journal of Chemical Engineering , 2008, DOI: 10.1590/S0104-66322008000100016
Abstract: computational fluid dynamics (cfd) is widely used by polymer processing industries in order to evaluate polymeric fluid flows. a successful computational code must provide reliable predictions (modeling) in a fast and efficient way (simulation). in this work, a new approach to solve the governing equations of viscoelastic fluid flows is proposed. it is based on the finite-volume method with collocated arrangement of the variables, using high-order approximations for the linear and nonlinear average fluxes in the interfaces and for the nonlinear terms obtained from the discretization of the constitutive equations. the approximations are coupled to the weighted essentially non-oscillatory (weno) scheme to avoid oscillations in the solution. the oldroyd-b model is used to describe the rheological behavior of the viscoelastic fluid. the average values of the variables in the volumes are used during the resolution, and the point values are recovered in the post-processing step by deconvolution of the average values. the nonlinear system, resulting from the discretization of the equations, is solved simultaneously using a newton-like method. the obtained solutions are oscillation-free and accurate, demonstrated by the application on a classic problem in computational fluid dynamics, the slip-stick flow.
Simulation of styrene polymerization reactors: kinetic and thermodynamic modeling
Almeida, A. S.;Wada, K.;Secchi, A. R.;
Brazilian Journal of Chemical Engineering , 2008, DOI: 10.1590/S0104-66322008000200012
Abstract: a mathematical model for the free radical polymerization of styrene is developed to predict the steady-state and dynamic behavior of a continuous process. special emphasis is given for the kinetic and thermodynamic models, where the most sensitive parameters were estimated using data from an industrial plant. the thermodynamic model is based on a cubic equation of state and a mixing rule applied to the low-pressure vapor-liquid equilibrium of polymeric solutions, suitable for modeling the auto-refrigerated polymerization reactors, which use the vaporization rate to remove the reaction heat from the exothermic reactions. the simulation results show the high predictive capability of the proposed model when compared with plant data for conversion, average molecular weights, polydispersity, melt flow index, and thermal properties for different polymer grades.
Scaling behavior for ionic transport and its fluctuations in individual carbon nanotubes
E. Secchi,A. Nigues,L. Jubin,A. Siria,L. Bocquet
Physics , 2015,
Abstract: In this letter we perform an experimental study of ionic transport and current fluctuations inside individual Carbon Nanotubes (CNT). The conductance exhibits a power law behavior at low salinity, with an exponent close to 1/3 versus the salt concentration. This scaling behavior is rationalized in terms of a model accounting for hydroxide adsorption at the (hydrophobic) carbon surface, leading to a density dependent surface charge. This is in contrast to boron nitride nanotubes which exhibit a constant surface conductance. Further we measure the low frequency noise of the ionic current in CNT and show that the amplitude of the noise scales with the surface charge, with data collapsing on a master curve for the various studied CNT at a given pH.
Development of a high-order finite volume method with multiblock partition techniques
Lemos, E. M.;Secchi, A. R.;Biscaia Jr, E. C.;
Brazilian Journal of Chemical Engineering , 2012, DOI: 10.1590/S0104-66322012000100019
Abstract: this work deals with a new numerical methodology to solve the navier-stokes equations based on a finite volume method applied to structured meshes with co-located grids. high-order schemes used to approximate advective, diffusive and non-linear terms, connected with multiblock partition techniques, are the main contributions of this paper. combination of these two techniques resulted in a computer code that involves high accuracy due the high-order schemes and great flexibility to generate locally refined meshes based on the multiblock approach. this computer code has been able to obtain results with higher or equal accuracy in comparison with results obtained using classical procedures, with considerably less computational effort.
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