232 research outputs found
Multifractal analysis of vertical total electron content (VTEC) at equatorial region and low latitude, during low solar activity
This paper analyses the multifractal aspects of the GPS data (measured
during a period of low solar activity) obtained from two Brazilian stations:
Belém (01.3° S, 48.3° W) and São José dos Campos (SJC)
(23.2° S, 45.9° W). The results show that the respective
geographic sites show important scaling differences as well as similarities
when their multifractal signatures for vertical total electron content (VTEC) are compared. The
<I>f</I>(α) spectra have a narrow shape for great scales, which
indicates the predominance of deterministic phenomena, such as solar
rotation (27 days) over intermittent phenomena. Furthermore, the <I>f</I>(α) spectra for both sites have a strong multifractality
degree at small scales. This strong multifractality degree observed at small
scales (1 to 12 h) at both sites is because the ionosphere over Brazil
is a non-equilibrium system. The differences found were that Belém
presented a stronger multifractality at small scales (1 h to 12 h)
compared with SJC, particularly in 2006. The reason for this behaviour
may be associated with the location of Belém, near the geomagnetic
equator, where at this location the actions of X-rays, ultraviolet, and
another wavelength from the Sun are more direct, strong, and constant
throughout the whole year. Although the SJC site is near ionospheric
equatorial anomaly (IEA) peaks, this interpretation could explain the higher
values found for the intermittent parameter μ for Belém compared
with SJC. Belém also showed the presence of one or two flattening
regions for <I>f</I>(α) spectra at the same scales mentioned before. These
differences and similarities also were interpreted in terms of the IEA
content, where this phenomenon is an important source of intermittence due
the presence of the VTEC peaks at ±20°
geomagnetic latitudes
Electrical conductance of hydrogen chloride in dimethylsulphoxide at 25°C
The electrical conductance of hydrogen chloride solutions in DMSO at 25°C has been studied. The limiting molar conductance is 38·7 int mho cm2 int mho cm2/mol. Conductivity data were interpreted with the Fuoss' theory for associated 1-1 type electrolytes. The association constant related to pair formation is 115·7 l/mol. The mechanism of electricl conduction of HCl in DMSO at infinite dilution resembles that of other 1-1 type electrolytes in the same solvent, in which charges are transported by simple entities in a viscous continuum.On a étudié la conductivité électrique des solutions de chlorure d'hydrogéne dans le DMSO à 25°C. La conductivité limite molare est de 38,7 mho int cm2/mol. Les données expŕimentalles de la conductivité furent interprétées d'aprés la théorie de Fuoss pour des électrolytes associé du type 1-1. La constante d'association liée à la formation de paires ioniques simple est 115,7 l/mol. Le mechanisme de la conduction électrique du HCl dans le DMSO à dilution infinie ressemble celui des autres électrolytes du type 1-1 dans le même dissulvant, puisque les charges sont transportées par des entités simples dans un milieu visqueux continu.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicada
Effect of temperature on the electrical conductance of hydrogen chloride in dimethylsulphoxide
The electrical conductance of solutions of hydrogen chloride in dimethylsulphoxide at temperature from 25 to 45°C has been studied. Results have been interpreted with the Fouss theory for associated 1-1 type electrolytes. Values of the association constant KA and the J parameter have been computed at each temperature. The temperature dependence of the molar conductance is inferred from the theoretical equation and related to the temperature dependence of viscosity.La conductance électrique des solutions de chlorure d'hydrogène dans le diméthylsulfoxyde à des températures de 25 a 45°C a été étudiée. Les résultats ont et́é inteprétés par la théorie de Fuoss pour de electrolytes associées du type 1-1. Les valeurs de la constante d'association KA et du paramètre J ont été calculées à chaque température. La dépendance de la conductivité molare avec la température est déduite de l'équation théorique et référée a la dépendance de la viscosité avec la température.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicada
Influence of the Location of the Internal Temperature Control Loop on the Performance of the Dual Temperature Control for Feed Temperature Disturbance
A control strategy with distributed corrective action for distillation has been proposed and consists of a conventional dual temperature control combined with an additional column tray. In this work, we evaluated the influence of the location of this internal loop as part of the new proposal, compared to a conventional system. Tests were
carried out in a 13-column tray distillation equipment and feed temperature was disturbed. Two different column trays from the stripping section were used (11 and 12) for internal decentralized temperature control, each one separately, plus the dual control of
top and bottom temperatures. The results demonstrated that this proposed control approach with distributed corrective action is faster than the conventional one, regardless of the column tray in use. It was also determined that the internal loop close to the feed
(disturbance) is more interesting as a way to minimize transients
Comparison of <i>H</i> component geomagnetic field time series obtained at different sites over South America
The
geomagnetic field in the Brazilian sector is influenced by the South American
Magnetic Anomaly (SAMA) that causes a decrease in the magnitude of the local
geomagnetic field when compared to other regions in the world. Thus, the
magnetometer network and data set of space weather over Brazil led by Embrace
are important tools for promoting the understanding of geomagnetic fields
over Brazil. In this sense, in this work we used the H component of
geomagnetic fields obtained at different sites in South America in order to
compare results from the phase coherence obtained from wavelet transform
(WT). Results from comparison between Cachoeira Paulista (CXP) and
Eusébio (EUS), and Cachoeira Paulista and São Luis (SLZ), indicated
that there exist some phenomena that occur simultaneously in both locations,
putting them in the same phase coherence. However, there are other phenomena
putting both locations in a strong phase difference as observed between CXP
and Rio Grande, Argentina (RGA). This study was done for a specific moderate
geomagnetic storm that occurred in March 2003. The results are explained in
terms of nonlinear interaction between physical phenomena acting in distinct
geographic locations and at different times and scales
A Description of the Transport Critical Current Behavior of Polycrystalline Superconductors Under the Applied Magnetic Field
- …