Impact of Distance Determinations on Galactic Structure. II. Old Tracers

Here we review the efforts of a number of recent results that use old tracers to understand the build up of the Galaxy. Details that lead directly to using these old tracers to measure distances are discussed. We concentrate on the following: (1) the structure and evolution of the Galactic bulge and inner Galaxy constrained from the dynamics of individual stars residing therein; (2) the spatial structure of the old Galactic bulge through photometric observations of RR Lyrae-type stars; (3) the three-dimensional structure, stellar density, mass, chemical composition, and age of the Milky Way bulge as traced by its old stellar populations; (4) an overview of RR Lyrae stars known in the ultra-faint dwarfs and their relation to the Galactic halo; and (5) different approaches for estimating absolute and relative cluster ages.     

To simulation of fan blade out for a high bypass ratio engine

The results of simulating the dynamic characteristics of turbofan engines (TFE) during and after fan blade-out are presented. To solve the tasks, we constructed a nonlinear unsteady engine model that includes the low pressure rotor, high pressure rotor, cases, nacelle with reverse, engine hanger to the pylon, pylon itself, and aircraft hanger of the pylon to the wing. The rotor system model also includes the rolling bearings (stiffness of which is calculated for engine operation in different operating regimes), nonlinear hydrodynamic dampers, and elastic bushes (“squirrel cages”).     

Evaluation of the spectrometric and dose characteristics of neutron fields inside the Russian segment of the ISS by fission detectors

The results of measuring the dose and the energy spectrum of neutrons inside the Russian segment of the International Space Station (ISS) from March 21 until November 10, 2002 are presented. Statistically reliable results of measurement are obtained by using thorium- and uranium-based fission detectors with cadmium and boron filters. The kits of the detectors with filters have been arranged in three compartments within assembled passive detectors in the BRADOS space experiment. The ambient dose rate H* = 139 μSv day and an energy spectrum of neutrons in the range of 10^–2–10⁴ MeV is obtained as average for the ISS compartments and is compared with the measurements carried out inside the compartments of the MIR space station. Recommendations on how to improve the procedure for using the fission detectors to measure the characteristics of neutron fields inside the compartments of space stations are formulated.     

An integrated system of operation mode synchronization for the helicopter powerplant engines

We consider the problem of synthesizing the control system of the helicopter power plant that consists of two turboshaft engines with free turbines, which through an overall mechanical transmission rotate the helicopter uniaxial rotors. We discuss the problem of coordinating the dynamic characteristics of the individual control loops, when the modes of operation are changed with the aim of balancing the load of each of the two engines.     

On the Non-coplanar Transfer of Type II between Two Circular Orbits

The paper regards two-impulse transfer from a low parking orbit into a circular orbit with the altitude less than 36 000 km, while the inclination correction is carried out with each maneuver. An approximate formula is proposed capable of evaluating analytically the optimal value of the first correction of inclination; the corresponding accuracy data are given. Examples are provided to show the operational efficiency of an optimal non-coplanar transfer of the type II with injections of satellites into various target orbits from Russian launch sites with due account of the available launch azimuths.     

Collapse of a spheroidal cavitation bubble near a solid wall

Dynamics of a gas bubble in a liquid near a solid wall is studied. The influence of the initial spheroidal disturbances of the bubble shape and the distance to the wall on the dynamics of the bubble–liquid system is analyzed. The pressure in the bubble is initially greater than that of the surrounding liquid. An algorithm based on the Euler scheme and the boundary element method is applied in the calculations.     

Influence of an oil supply process on the characteristics of plain journal bearings

In this paper, we present some experimental data on characteristics of plain journal bearings at different variants of oil supply inlet pipe arrangement and relative values of the shaft rotation speed and inlet pipe pressure. Also established is the significant growth of oil consumption when the inclination angle of the inlet throttling element axis is increased.     

Problems in formation and control of a required microacceleration level at spacecraft design,tests, and operation

In this paper, we consider the main aspects of a problem in formation and control of a required microacceleration level as the most important characteristic of the space laboratory intended for realizing the gravitational and sensitive technological processes. The estimation model and methodology to control and estimate the microaccelerations are presented that are necessary for the well-founded choice of the spacecraft parameters and carrying out their flight and space tests, when the new special-purpose space laboratories are designed and constructed.     

Influence of the gas-distributing grid structural features on the flow parameters in the liquid-propellent rocket engine with producer gas afterburning

The analysis of structural features of the gas-distributing grid was carried out by modern facilities of computational gas dynamics to equalize flow parameters upstream of a mixing head in LPRE with producer gas afterburning. For the given simulation conditions we defined the optimal geometrical dimensions of the facets on the gas-distributing grid openings, providing the maximal discharge coefficient and the minimal pressure differential. We also examined the grid design variants with the various distribution of facets of different geometry, which allows the outflow parameters to be varied according to the grid area. It is obtained, that a flat grid with various openings geometry in the sectors makes it possible to provide the best equalization of the pressure and velocity fields upstream of the mixing head and the minimal pressure losses.     

Nonlinear dynamics of antennas in space communication facilities

A mathematical model of complex vibrations for the cantilever Bernoulli-Euler beam in the XOZ plane constructed by the finite difference and finite element methods and the fourth-order Runge-Kutta method is presented. We determined the critical value of the damping coefficient ɛ = 0.28, at which the system changes from the dissipative state to conservative one, using the Morlet wavelet. The results of analyzing the frequency characteristics of the system are presented.