Plasmaspheric electron content derived from GPS TEC and FORMOSAT-3/COSMIC measurements: Solar minimum condition

The plasmaspheric electron content (PEC) was estimated by comparison of GPS TEC observations and FORMOSAT-3/COSMIC radio occultation measurements at the extended solar minimum of cycle 23/24. Results are retrieved for different seasons (equinoxes and solstices) of the year 2009. COSMIC-derived electron density profiles were integrated up to the height of 700 km in order to retrieve estimates of ionospheric electron content (IEC). Global maps of monthly median values of COSMIC IEC were constructed by use of spherical harmonics expansion. The comparison between two independent measurements was performed by analysis of the global distribution of electron content estimates, as well as by selection specific points corresponded to mid-latitudes of Northern America, Europe, Asia and the Southern Hemisphere. The analysis found that both kinds of observations show rather similar diurnal behavior during all seasons, certainly with GPS TEC estimates larger than corresponded COSMIC IEC values. It was shown that during daytime both GPS TEC and COSMIC IEC values were generally lower at winter than in summer solstice practically over all specific points. The estimates of PEC (h > 700 km) were obtained as a difference between GPS TEC and COSMIC IEC values. Results of comparative study revealed that for mid-latitudinal points PEC estimates varied weakly with the time of a day and reached the value of several TECU for the condition of solar minimum. Percentage contribution of PEC to GPS TEC indicated the clear dependence from the time with maximal values (more than 50–60%) during night-time and lesser values (25–45%) during day-time.     

Concepts of Gas Turbine Engine Improvement Through the Use of Choked-Flow Turbines

The new conceptual design of simple gas turbine engines for different purposes is presented. A choked-flow low-pressure turbine is used that allows reducing the number of stages and gas temperature in the relative motion ahead of blades. Application of such turbines with uncooled blades to reduce the cost of power-limited engines is considered.     

Multicriteria choice of a carrier aircraft and main design parameters of an air launcher decoy

The multicriteria optimization problem on joint choice of a carrier aircraft and main design parameters of an air launcher decoy are considered. The estimation of the design parameter values for the aerial decoy is based on the statistical data processing with the use of the methods for constructing nonlinear regression. The result of solving this problem is a set of Pareto-optimal geometry characteristics of the carrier aircraft and aerial decoy. A person who is responsible for decision-making should choose the most reasonable variant from these characteristics. An example of solving the problem is presented.     

The effect of gyroscopic couples on disk-wing aircraft stability

We present the results of studying the dynamic stability of an aircraft with a rotating disk wing (disk-wing aircraft), from which the helicopter-type blades are extended at takeoff and landing. The aircraft trajectory, when entering a descending airflow, is studied.     

Computer-aided tests in the quality control system of aircraft engines

The quality control system for an aircraft engine that is continuously developed in the life cycle stages is considered. Main quality indicators and their control methodology are analyzed. The computer-aided tests are substantiated as part of the quality control system and their generalized technological process structure and its construction methodology are proposed.     

Digisonde observations of TIDs with frequency and angular sounding technique

A technique for studying ionospheric wavelike phenomena, primarily AGW/TID events, is developed based on the solution of the problem of radio wave propagation in ionospheric plasma disturbed by wavelike processes. A perfectly reflecting surface model is used for representing TIDs propagating at ionospheric heights. This technique is a generalization of the Frequency-and-Angular Sounding (FAS) method developed earlier for oblique TID diagnostics using transmitters of opportunity. Trial measurements were made in November 2003 with two DPS-4 systems at Millstone Hill Observatory, providing experimental validation of the developed method by comparing the results of disturbance diagnostics to those simultaneously obtained with the original (oblique) FAS method. The TID parameters recovered during the November 2003 campaign suggest that the observed disturbances predominately propagated equatorward which likely indicates their sources to be in the auroral region. The equatorward propagating AGW/TIDs are typical for disturbed geomagnetic conditions which were observed during the campaign. Implementation of the generalized FAS technique in the DPS sounder allowed development of a dedicated data acquisition system for ionospheric disturbance diagnostics. Routine measurements with the developed technique using the existing world-wide network of Digisondes (GIRO) will make it possible to conduct large-scale studies of the AGW/TID phenomena.     

Thermoelastic problem for a physically orthotropic cylindrical shell at localized temperature

Numerical results obtained based on the equations for the general theory of physically orthotropic shells are presented. These results illustrate the influence of anisotropy for mechanical and physical characteristics of material on stressed state.     

A study of Z-crimp structural parameters impact on strength under transverse compression and longitudinal shear

Results of exerimental studies for composite Z-crimp core geometry impact on strength under transverse compression and longitudinal shear are presented. Recommendations are given concerning selection of core structural parameters to increase its strength for the specified types of loading at the same volumetric density. Mechanical properties of panels with different composite cores are compared.