100 research outputs found
The termal deformation reducing in sheet metal at manufacturing parts by CNC cutting machines
In various industries for the manufacturing of parts (workpieces) from sheet metal the CNC machines for thermal cutting (laser/plasma/gas cutting) are used. During process of thermal cutting, various deformations of the metal can occur, that cause the distortion of the geometric forms and sizes of the cut parts. These distortions are caused both by the uneven distribution of temperature in the sheet, and by certain geometric characteristics of the cutting process. Geometric characteristics are determined by the set sequence (order) of cutting of figured parts, as well as by selecting the piercing points of sheet material, i.e. the places of inserting the tool into the material. Previously, the authors formulated heuristic geometric rules, that allow reducing the value of geometric deformations of parts produced by the CNC cutting machines. To comply with these rules, users of Computer-Aided Design (CAM) systems that are used to generate NC programs, have to use interactive design methods. One of these rules (so-called "Part Hardness Rule") refers to the selecting the location of points for inserting (piercing) a CNC machine tool into the material. The paper describes a model based on the use of the heat conduction equation, which makes it possible to calculate the temperature of the sheet material at each moment of cutting process. The computational experiments showed that the points, which according to the "Part Hardness Rule" can't be used for piercing, have a higher material temperature than the points that satisfy this rule. In the paper the results of the computational experiments are given. Another rule (socalled "Sheet Hardness Rule"), which also reduces the deformation of the material during thermal cutting, refers to the order of parts cutting from the sheet. A heuristic algorithm that automatically generates the order of cutting parts that satisfy the rules of "Part Hardness" and of "Sheet Hardness" is developed. Developed software allows us to abandon the interactive methods of the NC programs generation for the thermal cutting of figured parts on CNC machines. © 2019 IOP Publishing Ltd. All rights reserved.Russian Foundation for Basic Research, RFBRThe work was supported by the Russian Foundation for Basic Research (grant 19-01-00573)
V2324Cyg - an F-type star with fast wind
For the first time high-resolution optical spectroscopy of the variable star
V2324Cyg associated with the IR-source IRAS20572+4919 is made. More than 200
absorption features (mostly FeII, TiII, CrII, YII, BaII, and YII) are
identified within the wavelength interval 4549-7880AA. The spectral type and
rotation velocity of the star are found to be F0III and Vsini=69km/s,
respectively. HI and NaID lines have complex PCyg-type profiles with an
emission component. Neither systematic trend of radial velocity Vr with line
depth Ro nor temporal variability of Vr have been found. We determined the
average heliocentric radial velocity Vr=-16.8\pm 0.6km/s. The radial velocities
inferred from the cores of the absorption components of the H and NaI
wind lines vary from -140 to -225km/s (and the expansion velocities of the
corresponding layers, from about 120 to 210km/s). The maximum expansion
velocity is found for the blue component of the split H absorption:
450km/s for December 12, 1995. The model atmospheres method is used to
determine the star's parameters: Teff=7500K, log g=2.0, =6.0km/s, and
metallicity, which is equal to the solar value. The main peculiarity of the
chemical abundances pattern is the overabundance of lithium and sodium. The
results cast some doubt on the classification of V2324Cyg as a post-AGB star.Comment: 28 pages, 6 figure
Two New LBV Candidates in the M33 Galaxy
We present two new luminous blue variable (LBV) candidate stars discovered in
the M33 galaxy. We identified these stars (Valeev et al. 2010) as massive star
candidates at the final stages of evolution, presumably with a notable
interstellar extinction. The candidates were selected from the Massey et al.
(2006) catalog based on the following criteria: emission in Halpha, V<18.5 and
0.35<(B-V)<1.2. The spectra of both stars reveal a broad and strong Halpha
emission with extended wings (770 and 1000 km/s). Based on the spectra we
estimated the main parameters of the stars. Object N45901 has a bolometric
luminosity log(L/Lsun)=6.0-6.2 with the value of interstellar extinction
Av=2.3+-0.1. The temperature of the star's photosphere is estimated as
Tstar~13000-15000K its probable mass on the Zero Age Main Sequence is
M~60-80Msun. The infrared excess in N45901 corresponds to the emission of warm
dust with the temperature Twarm~1000K, and amounts to 0.1% of the bolometric
luminosity. A comparison of stellar magnitude estimates from different catalogs
points to the probable variability of the object N45901. Bolometric luminosity
of the second object, N125093, is log(L/Lsun)=6.3-6.6, the value of
interstellar extinction is Av=2.75+-0.15. We estimate its photosphere's
temperature as Tstar~13000-16000K, the initial mass as M~90-120Msun. The
infrared excess in N125093 amounts to 5-6% of the bolometric luminosity. Its
spectral energy distribution reveals two thermal components with the
temperatures Twarm~1000K and Tcold~480K. The [CaII] lines (7291A and 7323A),
observed in LBV-like stars VarA and N93351 in M33, are also present in the
spectrum of N125093. These lines indicate relatively recent gas eruptions and
dust activity linked with them. High bolometric luminosity of these stars and
broad Halpha emissions allow classifying the studied objects as LBV candidates.Comment: 14 pages, 4 figure
Evolutionary stage of the spectral variable BD+48 1220=IRAS 05040+4820
Based on high-resolution observations (R=60000 and 75000), we have studied
the optical spectral variability of the star BD+48 1220 (IRAS05040+4820). We
have measured the equivalent widths of numerous absorption lines of neutral
atoms and ions at wavelengths from 4500 to 6760 AA, as well as the
corresponding radial velocities. We use model atmospheres to determine
Teff=7900K, log g=0.0, microturbulence velocity xi_t=6.0, and the abundances
for 16 elements. The star's metallicity differs little from the solar value:
[Fe/H]=-0.10 dex. The main peculiarity of the chemical composition of the star
is a large He-excess, derived from the HeI 5876 A absorption, [He/H]=+1.04, and
the equally large O-excess, [O/Fe]=+0.72 dex. The C-excess is small,
[C/Fe]=+0.09 dex, and the ratio [C/O] 1. We obtained a revised relation
for the light-metal abundances: [Na/Fe]=+0.87 with [Mg/Fe]=-0.31. The barium
abundance is low, [Ba/Fe]=-0.84. The radial velocity of the star measured from
photospheric absorption lines over three years of observations varies in the
interval V_sun = -(7 - 15) km/s. Time variable differential line shifts have
been revealed. The entire set of available data (the luminosity Mv~-5m,
velocity V_lsr~-20 km/s, metallicity [Fe/H]=-0.10, and peculiarities of the
optical spectrum and chemical composition) confirms the status of BD+48 1220 as
a post-AGB star with He- and O-excesses belonging to the Galactic disk.Comment: 42 pages, 7 figures, 6 tables, accepted by Astronomy Report
Optical spectrum of the post-AGB star HD56126 in the region 4010-8790 AA
We studied in detail the optical spectrum of the post-AGB star HD56126
(IRAS07134+1005). We use high resolution spectra (R=25000 and 60000) obtained
with the echelle spectrographs of the 6-m telescope. About one and a half
thousand absorptions of neutral atoms and ions, absorption bands of C_2, CN,
and CH molecules, and interstellar bands (DIBs) are identified in the 4010 to
8790 AA wavelength region, and the depths and radial velocities of these
spectral features are measured. Differences are revealed between the variations
of the radial velocities measured from spectral features of different
excitation. In addition to the well-known variability of the Halpha profile, we
found variations in the profiles of a number of FeII, YII, and BaII lines. We
also produce an atlas of the spectrum of HD56126 and its comparison staralpha
Per. The full version of the atlas is available in electronic form from
Web-address: http://www.sao.ru/hq/ssl/Atlas/Atlas.htmlComment: 42 pages, 6 figure
Detection of the spectral binary (SB2) nature of BD-6^o1178
BD-6^o1178 identified with the infrared source IRAS05238-0626 is shown for
the first time to be a spectroscopic binary (SB2) by analyzing the
high-resolution spectra taken with the NES echelle spectrograph of the 6-m
telescope. The components of the binary have close spectral types and
luminosity classes: F5IV-III and F3V. The heliocentric radial velocities are
measured for both components at four observing moments in 2004-2005. Both stars
have close rotation velocities, which are equal to 24 and 19km/s. We do not
confirm the classification of BD-6^o1178 as a supergiant in the transition
stage of becoming a planetary nebula. BD-6^o1178 probably is a young pre-MS
stars. It is possibly a member of the 1c subgroup of the OriOB1 association.Comment: 13 pages, 1 table, 4 figure
INTERFACIAL INTERACTION IN Ti -Al -(Nb, Ta, V) SYSTEM
Physical and chemical properties of Ti-Al - (Nb, Ta, V) alloys obtained by joint aluminothermal reduction of metals from oxides are studied. The influence of melting point and concentration of Nb, Ta, V on density and surface tension of alloys was studied
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