394 research outputs found
Cataclysmic Variables from USNO-B1.0 Catalog: Stars with Outbursts on Infrared Palomar Plates
The search was performed for cataclysmic variable stars with outlying
infrared magnitudes in USNO-B1.0 catalog. The selection was limited to objects
in the Northern hemisphere with (B1-R1) 3.5. The search method
is described, and the details on individual stars are given. In total 27
variable objects were found with 20 being the previously known ones and 7 - new
discoveries. 4 of newly found variables are dwarf novae, while the remaining 3
- pulsating red variables of Mira or semi-regular types, including a heavily
reddened one in Pelican nebula. The correct pulsation period is determined for
two stars discovered by other researchers, and the dwarf nova nature is
confirmed for another object previously suspected as such. The perspectives of
the proposed search technique in the framework of Virtual Observatory are also
discussed.Comment: 8 pages, 10 figures, submitted to Astronomy Letter
Identification of new cataclysmic variables in the 1RXS and USNO-B1.0 catalogs
As a result of applying the original optical variability search method on
publicly available data, we have found eight new cataclysmic variables and two
possible Optically Violent Variable quasars among the previously unidentified
X-ray sources in the ROSAT catalog. We describe the search method and present
the characteristics of the newly identified variable stars. The obtained
results demonstrate the large potential of the concept of Virtual Observatory
for identifying new objects of astrophysical interest.Comment: 16 pages, 11 figures, 2 tables; submitted to Astronomy Letter
New Cataclysmic Variable 1RXS J073346.0+261933 in Gemini
In course of the search for the optical identifications associated with ROSAT
X-ray sources we have found a highly variable object with the very unusual
long-term behavior, color indices and high X-ray-to-optical flux ratio. We
report the archival photometric light curve from the Catalina Sky Survey,
optical spectroscopy from RTT150 and time-resolved photometry from
Astrotel-Caucasus telescope. The object appears to be the magnetic cataclysmic
variable (polar) with orbital period of P=3.20 hr.Comment: 8 pages, 5 figures. Submitted to Astronomy Letter
LC nanocomposites: induced optical singularities, managed nano/micro structure, and electrical conductivity
Microstructure, phase transitions, electrical conductivity, and optical and
electrooptical properties of multiwalled carbon nanotubes (NTs), dispersed in
the cholesteric liquid crystal (cholesteryl oleyl carbonate, COC), nematic 5CB
and their mixtures, were studied in the temperature range between 255 K and 363
K. The relative concentration X=COC/(COC+5CB)was varied within 0.0-1.0. The
concentration of NTs was varied within 0.01-5% wt. The value of X
affected agglomeration and stability of NTs inside COC+5CB. High-quality
dispersion, exfoliation, and stabilization of the NTs were observed in COC
solvent ("good" solvent). From the other side, the aggregation of NTs was very
pronounced in nematic 5CB solvent ("bad" solvent). The dispersing quality of
solvent influenced the percolation concentration , corresponding to
transition between the low conductive and high conductive states: e.g.,
percolation was observed at and for pure COC and 5CB,
respectively. The effects of thermal pre-history on the heating-cooling
hysteretic behavior of electrical conductivity were studied. The mechanism of
dispersion of NTs in COC+5CB mixtures is discussed. Utilization of the mixtures
of "good" and "bad" solvents allowed fine regulation of the dispersion,
stability and electrical conductivity of LC+NTs composites. The mixtures of COC
and 5CB were found to be promising for application as functional media with
controllable useful chiral and electrophysical properties.Comment: 10 pages, 9 figure
Research of the rotor end winding ventilation ducts effect on the thermal state of enclosed synchronous generator
В данной статье рассматривается влияние вентиляционных каналов в торцевых частях обмотки возбуждения генератора на общий среднеобъемный перегрев обмотки возбуждения относительно поступающего в межполюсное пространство воздуха с помощью численного моделирования в пакете ANSYS.In this paper the number and size effect of the end rotor winding ventilation ducts in synchronous generator SG-60 on volume average winding temperature rise over the inflow air using numerical modeling approach in ANSYS is considered
Calculation of the spatial equivalent scheme of the magnetic circuit of the asynchronous motor with an asymmetric magnetic core
Картина магнитного поля в асинхронном двигателе с асимметричным магнитопроводом претерпевает значительные изменения. С увеличением пазового рассеяния возникает осевая составляющая магнитного потока. В данном докладе рассчитывается магнитная цепь с целью оценки величины осевой составляющей по отношению к основному магнитному полю и меры борьбы с ним.The picture of the magnetic field in the induction motor with an asymmetric magnetic core is undergoing significant changes. With increasing scattering occurs grooved axial component of the magnetic flux. The report calculated the magnetic circuit in order to assess the magnitude of the axial component relative to the main magnetic field and measures to combat it
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