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Profiles of the Fe IX line at a wavelength of λ = 17.1 nm in the radiation spectrum of slow magneto-acoustic waves, propagating in coronal loops, are calculated under conditions of an optically ...thin layer and a constant density. The parameter values used in calculations of the line profiles are as follows: the amplitude of the velocity of particles’ displacements in a wave
v
0
= 10 km/s, the width of the coronal loop is 2000 and 5000 km, the wavelength Λ = 20 000 km and 50 000 km, and the value of the Doppler width Δλ
d
= 1 pm; the values for the angle of view and the wave phases were varied. The true value of the energy flux density is 622 erg/cm
2
s. The values of the energy flux density obtained in calculations strongly depend on the angle of view θ and the wave phase: they range from 0 and, when the values of θ are large, to 2000 erg/cm
2
s. The values of the Doppler velocities
v
d
and the velocities of nonthermal motions
v
nt
take maximal values of ~12 km/s at small angles θ and almost vanish at large angles θ. When the angle of view is small (θ < 30°), a weak blue asymmetry is noticeable. When the angle of view is large (θ > 30°), the asymmetry is almost invisible.
In this work, for planetary nebulae İC 1295, İC 4191, Zanstra temperatures were calculated using the Hβ line of the central stars. Respectively, the temperatures 64252 K and 47663 K were determined. ...The flux in the Hβ radiative line used in the calculations, has been determined from the spectra retrieved from the archive of the European Southern Observatory. Our results have been compared with results of the other authors.
The results of spectral observations of the Algol-type binary star δ Lib are presented. The behavior of Hα and Hβ lines in the star’s spectrum during the orbital period phase is described. Based on ...our measurements of the radial velocities of the Hα and Hβ lines and using published data, the radial velocity curves of both components of the δ Lib system were constructed. In some phases of the orbital period, an absorption component was detected in the blue, or red, part of the Hα and Hβ line profiles. The observed Hα and Hβ absorption lines are attributed to the main component of the binary system δ Lib. It is assumed that the appearance of absorption components at these lines is associated either with suspicion of a third component in the system, or at these phases of the Hα and Hβ lines, the primary and secondary components of the δ Lib system are observed simultaneously.
This paper deals with the problem of global practical tracking for a class of high-order nonlinear systems with time delay. The peculiarity of the system under study is that the degree of restriction ...on the upper limit of nonlinearity can be obtained in a continuous interval. By introducing a sign (signum) function and adding a generalized method for enabling the power integrator, as well as selecting the corresponding Lyapunov function, we create an adjustable and time-independent tracking controller that will dominate the time-delayed nonlinearity. All the closed system states obtained as a result of the developed controller are widely limited and ensure that the tracking error after the set time is sufficiently small. A numerical example is given to demonstrate the effectiveness and validity of the proposed design.
In this paper, we study the problem of global practical tracking of a class of high-order nonlinear systems with feedback. A feature of the system under consideration is that the degree of limitation ...of the upper boundary of the nonlinearity is taken on a continuous interval. We develop a tunable and delayindependent tracking controller that dominates the effect of delay time non-linearity by generating a Lyapunov function, respectively, using a generalized method of adding a signum function and a power integrator. The resulting controller ensures global boundedness of all states of the studied closed system and a sufficiently small control error over a finite time. In addition, in this work, priority was given to computer simulation of previously achieved results.
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