995 resultados para BINARY-SYSTEMS


Relevância:

60.00% 60.00%

Publicador:

Resumo:

The objective of this work is the development of a methodology for electric load forecasting based on a neural network. Here, it is used Backpropagation algorithm with an adaptive process based on fuzzy logic. This methodology results in fast training, when compared to the conventional formulation of Backpropagation algorithm. Results are presented using data from a Brazilian Electric Company and the performance is very good for the proposal objective.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

In this work we studied the changes of the optical constants of films in the binary system Sb2O3-Sb2S3 induced by light in the VIS-UV. The measurements were performed before and after homogeneous irradiation of the films to a Hg lamp and in real time during the holographic exposure of the samples (at 458nm). Changes of the absorption coefficient (amplitude grating) and refractive index (phase grating) were measured simultaneously using the self-diffraction using the holographic setup. Besides the films presented a strong photodarkening effect under homogeneous irradiation, the samples holographically exposed presented only refractive index modulations. None amplitude modulation was measured in real time for spatial frequencies of about 1000 l/mm. © 2009 SPIE.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

Pós-graduação em Ciências Farmacêuticas - FCFAR

Relevância:

60.00% 60.00%

Publicador:

Resumo:

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Relevância:

60.00% 60.00%

Publicador:

Resumo:

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Relevância:

60.00% 60.00%

Publicador:

Resumo:

Pós-graduação em Química - IQ

Relevância:

60.00% 60.00%

Publicador:

Resumo:

This paper raises questions about the ways in which corporeality and processes desiring were built within binary systems, universalistic and subjected to imprisonment restricted to heteronormativity and phallocentrism, and most often, the only references that guide the schools, their curricula and assessment systems. Critically and expanded the questions between the schools, and their agents and their expressions of dissent corporeality, gender, sexuality, gender and other markers of social stigmas. Presents readings that show that even still conservative schools already produce programs that facilitate discussions on diversity and human and allow you to create pedagogies and educational policies that may be secular, democratic and inclusive

Relevância:

60.00% 60.00%

Publicador:

Resumo:

The existence of millisecond pulsars with planet-mass companions in close orbits is challenging from the stellar evolution point of view. We calculate in detail the evolution of binary systems self-consistently, including mass transfer, evaporation, and irradiation of the donor by X-ray feedback, demonstrating the existence of a new evolutionary path leading to short periods and compact donors as required by the observations of PSR J1719-1438. We also point out the alternative of an exotic nature of the companion planet-mass star.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

This Thesis is devoted to the study of the optical companions of Millisecond Pulsars in Galactic Globular Clusters (GCs) as a part of a large project started at the Department of Astronomy of the Bologna University, in collaboration with other institutions (Astronomical Observatory of Cagliari and Bologna, University of Virginia), specifically dedicated to the study of the environmental effects on passive stellar evolution in galactic GCs. Globular Clusters are very efficient “Kilns” for generating exotic object, such as Millisecond Pulsars (MSP), low mass X-ray binaries(LMXB) or Blue Straggler Stars (BSS). In particular MSPs are formed in binary systems containing a Neutron Star which is spun up through mass accretion from the evolving companion (e.g. Bhattacharia & van den Heuvel 1991). The final stage of this recycling process is either the core of a peeled star (generally an Helium white dwarf) or a very light almos exhausted star, orbiting a very fast rotating Neutron Star (a MSP). Despite the large difference in total mass between the disk of the Galaxy and the Galactic GC system (up a factor 103), the percentage of fast rotating pulsar in binary systems found in the latter is very higher. MSPs in GCs show spin periods in the range 1.3 ÷ 30ms, slowdown rates ˙P 1019 s/s and a lower magnetic field, respect to ”normal” radio pulsars, B 108 gauss . The high probability of disruption of a binary systems after a supernova explosion, explain why we expect only a low percentage of recycled millisecond pulsars respect to the whole pulsar population. In fact only the 10% of the known 1800 radio pulsars are radio MSPs. Is not surprising, that MSP are overabundant in GCs respect to Galactic field, since in the Galactic Disk, MSPs can only form through the evolution of primordial binaries, and only if the binary survives to the supernova explosion which lead to the neutron star formation. On the other hand, the extremely high stellar density in the core of GCs, relative to most of the rest of the Galaxy, favors the formation of several different binary systems, suitable for the recycling of NSs (Davies at al. 1998). In this thesis we will present the properties two millisecond pulsars companions discovered in two globular clusters, the Helium white dwarf orbiting the MSP PSR 1911-5958A in NGC 6752 and the second case of a tidally deformed star orbiting an eclipsing millisecond pulsar, PSR J1701-3006B in NGC6266

Relevância:

60.00% 60.00%

Publicador:

Resumo:

[EN]A thermodynamic study is carried out on binary systems composed of propyl ethanoate with six alkanes, from pentane to decane. Vapor pressures of the ester and the isobaric vapor−liquid equilibria of these six mixtures were measured at 101.32 kPa in a small-capacity ebulliometer and also the mixing properties yE = vE,hE over a range of temperatures and at atmospheric pressure. Adequate correlations are drawn for the surfaces yE = yE(x,T) with an interpretation on the behavior of the mixtures and also using cp E data from literature.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

[EN]This paper presents the experimental measurements of isobaric vapor−liquid equilibria (iso-p VLE) and excess volumes (vE) at several temperatures in the interval (288.15 to 328.15) K for six binary systems composed of two alkyl (methyl, ethyl) propanoates and three odd carbon alkanes (C5 to C9). The mixing processes were expansive, vE > 0, with (δvE/δT)p > 0, and endothermic. The installation used to measure the iso-p VLE was improved by controlling three of the variables involved in the experimentation with a PC.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

[EN]This work studies the volumetric (VE m) and energetic (HE m) properties resulting from the mixing processes of binary systems and the corresponding ternary of two methyl esters (methanoate and pentanoate) with methanol. The three binaries produce net endothermic mixing effects, with important energetic interactions, with maximum values of HE m ffi 400 J mol 1 , for the (ester + ester) system. This produces expansive effects VE m > 0, but the binaries of the (methyl esters + methanol) give rise to contractions VE m < 0, due to the formation of molecular aggregates.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

Im Rahmen dieser Arbeit wurden experimentelle und theoretische Untersuchungen zum Phasen- und Grenzflächenverhalten von ternären Systemen des Typs Lösungsmittel/Fällungsmittel/Polymer durchgeführt. Diese Art der Mischungen ist vor allem für die Planung und Durchführung der Membranherstellung von Bedeutung, bei der die genaue Kenntnis des Phasendiagramms und der Grenzflächenspannung unabdingbar ist. Als Polymere dienten Polystyrol sowie Polydimethylsiloxan. Im Fall des Polystyrols kam Butanon-2 als Lösungsmittel zum Einsatz, wobei drei niedrigmolekulare lineare Alkohole als Fällungsmittel verwendet wurden. Für Polydimethylsiloxan eignen sich Toluol als Lösungsmittel und Ethanol als Fällungsmittel. Durch Lichtstreumessungen, Dampfdruckbestimmungen mittels Headspace-Gaschromatographie (VLE-Gleichgewichte) sowie Quellungsgleichgewichten lassen sich die thermodynamischen Eigenschaften der binären Subsysteme charakterisieren. Auf Grundlage der Flory-Huggins-Theorie kann das experimentell bestimmte Phasenverhalten (LLE-Gleichgewichte) in guter Übereinstimmung nach der Methode der Direktminimierung der Gibbs'schen Energie modelliert werden. Zieht man die Ergebnisse der Aktivitätsbestimmung von Dreikomponenten-Mischungen mit in Betracht, so ergeben sich systematische Abweichungen zwischen Experiment und Theorie. Sie können auf die Notwendigkeit ternärer Wechselwirkungsparameter zurückgeführt werden, die ebenfalls durch Modellierung zugänglich sind.Durch die aus den VLE- und LLE-Untersuchungen gewonnenen Ergebnissen kann die sog. Hump-Energie berechnet werden, die ein Maß für die Entmischungstendenz darstellt. Diese Größe eignet sich gut zur Beschreibung von Grenzflächenphänomenen mittels Skalengesetzen. Die für binäre Systeme gefundenen theoretisch fundierten Skalenparameter gelten jedoch nur teilweise. Ein neues Skalengesetz lässt erstmals eine Beschreibung über die gesamte Mischungslücke zu, wobei ein Parameter durch eine gemessene Grenzflächenspannung (zwischen Fällungsmittel/Polymer) ersetzt werden kann.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

Blue straggler stars (BSSs) are brighter and bluer (hotter) than the main-sequence (MS) turnoff and they are known to be more massive than MS stars.Two main scenarios for their formation have been proposed:collision-induced stellar mergers (COL-BSSs),or mass-transfer in binary systems (MT-BSSs).Depleted surface abundances of C and O are expected for MT-BSSs,whereas no chemical anomalies are predicted for COL-BSSs.Both MT- and COL-BSSs should rotate fast, but braking mechanisms may intervene with efficiencies and time-scales not well known yet,thus preventing a clear prediction of the expected rotational velocities.Within this context,an extensive survey is ongoing by using the multi-object spectrograph FLAMES@VLT,with the aim to obtain abundance patterns and rotational velocities for representative samples of BSSs in several Galactic GCs.A sub-population of CO-depleted BSSs has been identified in 47 Tuc,with only one fast rotating star detected.For this PhD Thesis work I analyzed FLAMES spectra of more than 130 BSSs in four GCs:M4,NGC 6397,M30 and ω Centauri.This is the largest sample of BSSs spectroscopically investigated so far.Hints of CO depletion have been observed in only 4-5 cases (in M30 and ω Centauri),suggesting either that the majority of BSSs have a collisional origin,or that the CO-depletion is a transient phenomenon.Unfortunately,no conclusions in terms of formation mechanism could be drawn in a large number of cases,because of the effects of radiative levitation. Remarkably,however,this is the first time that evidence of radiative levitation is found in BSSs hotter than 8200 K.Finally, we also discovered the largest fractions of fast rotating BSSs ever observed in any GCs:40% in M4 and 30% in ω Centauri.While not solving the problem of BSS formation,these results provide invaluable information about the BSS physical properties,which is crucial to build realistic models of their evolution.