V606 Cen: A Newly Formed Massive Contact Binary in a Hierarchical Triple System

V606 Centauri (V606 Cen) is an early B-type close binary with an orbital period of 1.4950935 days, and its complete light curves are very difficult to observe on the ground. By analyzing the continuous light curve obtained by TESS, we found that it is a marginal contact binary with a very low fill-out factor of about 2%. The O − C diagram of V606 Cen is constructed for the first time based on 118.8 yr of eclipse times. The O − C diagram has been found to show a downward parabolic change together with a cyclic oscillation with a semiamplitude of 0.0545 days and a period of 88.3 yr. The downward parabolic variation reveals a linear period decrease at a rate of dP/dt = −2.08 × 10−7 days yr−1 that can be explained by the mass transfer from the more massive component to the less massive one. Both the marginal contact configuration and the continuous period decrease suggest that V606 Cen is a newly formed contact binary via Case A mass transfer. The cyclic change in the O − C diagram can be explained by the light-travel time effect via the presence of a third body. The lowest mass of the tertiary companion is determined to be M 3 = 4.51 (±0.43) M ⊙ and the tertiary is orbiting around the central eclipsing binary in a nearly circular orbit (e = 0.33). All of the results indicate that V606 Cen is a newly formed massive contact binary in a hierarchical triple system.

Structural analysis of seasonal dynamics of daily growth of annual shoots of woolly-stemmed willow

Given the complex characteristics of woolly–stemmed willow. The necessity of studying the regularities of seasonal dynamics of daily growth of annual shoots is substantiated. The study used material from the model inbred-clone population. Empirical data were processed using structural–harmonic analysis methods. It was found that the seasonal dynamics of the daily growth of shoots is cyclic quasi–periodic. Empirical series of dynamics at the highest level of significance are approximated by sums of elementary harmonics with a period of oscillation of 9.2 to 92.0 days. Revealed high-amplitude harmonic with the oscillation period of 23.0 to 92.0 day and low amplitude with a period of oscillation of 9.2 to 18.4 days. On all the studied shoots only the fourth harmonics coincide with the oscillation period of 23.0 days. The main contribution to the seasonal dynamics of shoot growth is made by three high-amplitude harmonics, which form two main signals with oscillation periods of 23 and 36 days. Other harmonics have a modulating effect on the seasonal dynamics of shoot growth. The first harmonics with a period of oscillation 92.0 days determine the nonlinearity of the seasonal trend of growth of shoots. Higher harmonics with a period of oscillation of 9.2 to 15.3 days form the resulting quasi–cyclic oscillation. Significant interclonal and intraclonal differences in the rhythm of daily growth of annual shoots were not revealed. On this basis, the proposed recommendations for agroforestry–technical events in the plantings of woolly–stemmed willow.

New Photometric Investigation of the Solar-Type Shallow-Contact Binary HH Bootis

The short-period solar-type contact binary HH Boo was monitored photometrically for about 8 years. It is found that the CCD light curves in the B, V, R, and I bands obtained in 2010 are symmetric, while the multicolor light curves observed in 2011 and 2012 by several investigators showed a positive O’Connell effect where the maxima following the primary minima are higher than the other ones. This indicates that the light curve of the solar-type contact binary is variable. By analyzing our multicolor light curves with the Wilson-Devinney code (W-D code), it is confirmed that HH Boo is a W-type shallow-contact binary system with a mass ratio of q = 1.703(31) and a degree of contact factor of f = 12.86%(0.73%). By including 109 new determined times of light minimum together with those compiled from the literature, it is detected that the O-C diagram shows a cyclic oscillation with a period of T3 = 6.58(11) yr and an amplitude of A3 = 0.0018(1) d. The cyclic change may reveal the presence of an extremely cool third body orbiting the central binary.

MATHEMATICAL PHASE MODEL OF NEURAL POPULATIONS INTERACTION IN MODULATION OF REM/NREM SLEEP

Aim of the present study is to compare the synchronization of the classical Kuramoto system and the reaction - diffusion space time Landau - Ginzburg model, in order to describe the alternation of REM (rapid eye movement) and NREM (non-rapid eye movement) sleep across the night. These types of sleep are considered as produced by the cyclic oscillation of two neuronal populations that, alternatively, promote and inhibit the REM sleep. Even if experimental data will be necessary, a possible interpretation of the results has been proposed.

Investigation of Numerical Stability of Pipe-Flow Simulation under Strong Oscillation of Inlet Velocity

Pressure distribution inside a fluid-conveying pipe is significant information for reasonable pipe design or mitigation of pipe vibration caused by fluid impact. Generally, a steady solution of pressure information can be obtained based on traditional CFD simulation if the inlet velocity of pipe is time independent. Unfortunately, strong oscillation of inlet velocity often happens in real engineering operations such as fuel injection or pumping process. This paper focuses on the simulation of the transient phenomenon of fluid flow inside a pipe based on the time-dependant inlet velocity. A 2D numerical pipe with an elbow is built based on Eulerian scheme and structured mesh. It is found that numerical instability occurs and convergence becomes difficult if inlet velocity presents obvious cyclic oscillation with big amplitude. Numerical oscillation increases especially when inlet velocity decreases from a big value to zero. Traditional finite volume method and cavitation model are tried and numerical results show that the convergence can be improved evidently based on cavitation model although numerical instability can not be overcome completely.

Complex Period Variations of the Neglected W UMa-type Binary System NY Lyrae

Orbital-period variations of the neglected W UMa-type binary star, NY Lyr, were analyzed based on two newly determined eclipse times together with the others compiled from the literature. A cyclic oscillation with a period of 82.1 yr and an amplitude of 0.0247 d was discovered to be superimposed on a continuous period increase (dP/dt = +1.33 × 10−7 d yr−1). After the long-term period increase and the large-amplitude cyclic oscillation were removed from the O–C diagram, the residuals suggest that there is another small-amplitude period oscillation (A4 = 0.0053 d, P4 = 19.4 years) in the orbital period changes. As in the cases of AH Cnc and AD Cnc, both the continuous period increase and the two cyclic period oscillations make NY Lyr an interesting system to study in the future. In order to understand the evolutionary state of the binary system, new photometric and spectroscopic observations and a careful investigation on those data are needed.