422 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
Efeito de hospedeiros e temperaturas na biologia de Anastrepha grandis (Macquart, 1846) (Diptera: Tephritidae) e comprovação em campo, do modelo de exigências térmicas obtido em laboratório.
Dissertação (Mestrado). Mestre em Entomologia, Programa de Pós-Graduação em Entomologia, Instituto de Biologia, Universidade Federal de Pelotas, 2014. Orientador Dori Edison Nava (CPACT); co-orientador Flávio Roberto Mello Garcia
Ocupação de manchas florestais no Pantanal por duas espécies de roedores: Clyomys laticeps e Thrichomys pachyurus.
A fragmentação e a perda de habitat afetam de diferentes maneiras as comunidades biológicas. os efeitos variam muito de espécie para espécie, com algumas sendo extintas enquanto outras são beneficiadas. Tendo em vista o mosaico vegetacional que caracteriza a paisagem no Pantanal, o presente estudo relacionou o tamanho e o isolamento médio das manchas florestais à probabilidade de ocupação por duas espécies de roedores: Clyomys laticeps (Thomas, 1841) e Thrichomys pachyurus (Wagner, 1845)
Biologia de Anastrepha grandis (Macquart, 1846) (Diptera: Tephritidae) sob diferentes temperaturas.
O trabalho teve como objetivo estudar o efeito de temperaturas constantes sobre a biologia de adultos de A. grandis
Development of Anastrepha grandis (Diptera: Tephritidae) under constant temperatures and field validation of a laboratory model for temperature requirements.
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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
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