Generalization of experimental data on two-phase critical efflux through axisymmetric channels

The results of studying the characteristics of a two-phase flow being formed during adiabatic water efflux through axisymmetric cylindrical and Laval nozzle channels are presented. Experiments were carried out with saturated water in the range of initial pressures 0.6–4.0 MPa. The fluid efflux was performed into the air with atmospheric pressure. The generalizing relations for calculating thrust pulse and critical flowrate were obtained.     

Numerical simulation of a boiling up fluid flow in the variable cross-section channels

A physical and mathematical model of a boiling-up fluid flow in the variable crosssection channels is proposed. The numerical model is based on the solution of the Navier-Stokes nonstationary equations for compressible fluid by the implicit finite-difference method. We present the results of the numerical modeling for two-phase flow characteristics at the initial stage of the evaporation process and the steady-state quasistationary flow of a two-phase medium.     

Studying the positioning accuracy for dynamic (moving) objects with the use of multifrequency oblique-incidence sounding of ionospheric radio channels by chirp signals

The paper presents the methods and algorithms for positioning the dynamic (moving) objects using the oblique-incidence ionospheric sounding by chirp signals. Full-scale experiments have been performed to determine a distance to an object and its location.     

Remnant magnetic fields of Mars and their interaction with the solar wind

This work presents a review of studies of the Martian magnetic fields during the early Soviet missions to Mars in 1971–1974, which never approached Mars by closer than 1000 km before the experiment with the Magnetometer/Electronic Reflectometer (MAG/ER) on board the Mars Global Surveyor spacecraft, which could descend to altitudes of 80–100 km. At present, the experiment with the magnetometer (MAG) onboard the American MAVEN spacecraft adds new data, but the map of distribution of remnant magnetic fields of Mars and the picture of their interaction with the solar wind are already formed and, at its core, obviously, will not be revised. Thus, it would be very instructive to consider the following in detail: (a) what is already known regarding the features and distribution of remnant magnetic fields on Mars; (b) how they control the interaction of solar wind with a weakly magnetized planet (Mars); and (c) what is its distinction from another nonmagnetized planet (Venus).     

Hard X-Ray/Soft Gamma-Ray Experiments and Missions: Overview and Prospects

Starting from 1960s, a great number of missions and experiments have been performed for the study of the high-energy sky. This review gives a wide vision of the most important space missions and balloon experiments that have operated in the 10–600 keV band, a crucial window for the study of the most energetic and violent phenomena in the Universe. Thus it is important to take the stock of the achievements to better establish what we have still to do with future missions in order to progress in this field, to establish which are the technologies required to solve the still open issues and to extend our knowledge of the Universe.     

The Noise Model of the SEIS Seismometer of the InSight Mission to Mars

The SEIS (Seismic Experiment for Interior Structures) instrument on board the InSight mission to Mars is the critical instrument for determining the interior structure of Mars, the current level of tectonic activity and the meteorite flux. Meeting the performance requirements of the SEIS instrument is vital to successfully achieve these mission objectives. The InSight noise model is a key tool for the InSight mission and SEIS instrument requirement setup. It will also be used for future operation planning. This paper presents the analyses made to build a model of the Martian seismic noise as measured by the SEIS seismometer, around the seismic bandwidth of the instrument (from 0.01 Hz to 1 Hz). It includes the instrument self-noise, but also the environment parameters that impact the measurements. We present the general approach for the model determination, the environment assumptions, and we analyze the major and minor contributors to the noise model.     

Methods for investigating the unmanned aerial vehicle electric actuator performance in aeroelasticity tasks

Theoretical and experimental methods of investigating the performance of an electric actuator of maneuverable unmanned aerial vehicle (UAV) is considered in order to solve the aeroelasticity tasks. Models of the stability analysis for the rudder–actuator system as well as the examples of numerical and experimental studies of this system performance are given.