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.     

Assimilation of endmember variability in spectral mixture analysis for urban land cover extraction

Variable Endmember Constrained Least Square (VECLS) technique is proposed to account endmember variability in the linear mixture model by incorporating the variance for each class, the signals of which varies from pixel to pixel due to change in urban land cover (LC) structures. VECLS is first tested with a computer simulated three class endmember considering four bands having small, medium and large variability with three different spatial resolutions. The technique is next validated with real datasets of IKONOS, Landsat ETM+ and MODIS. The results show that correlation between actual and estimated proportion is higher by an average of 0.25 for the artificial datasets compared to a situation where variability is not considered. With IKONOS, Landsat ETM+ and MODIS data, the average correlation increased by 0.15 for 2 and 3 classes and by 0.19 for 4 classes, when compared to single endmember per class.     

Comparison of model and experimental ionospheric parameters at high latitudes

Modern use and study of the auroral region needs to attract a wider class of models for describing conditions of radio wave propagation in the ionosphere. In this paper the possibilities of the International Reference Ionosphere model, well-proven and widespread in the mid-latitudes, are investigated in the high latitude zone. Model and measured values of the critical frequency foF2 for two mid-latitude stations (Juliusruh and Goosebay) and four high-latitude ones (Loparskaya, Sodankyla, Sondrestrom, Thule) are compared. Deviations of medians, variations from day to day and solar activity trends seemed to be similar for both areas. This similarity is irrespective of the RZ12 index. Special attention is paid to the TEC parameter and its determination using 6 versions of models, a new version of the model IRI2010 (IRI-Plas) among them. It is shown that the IRI-Plas model significantly improves the definition of TEC in contrast to the versions of IRI2007 and the new model NeQuick. The use of the median of the experimental equivalent slab thickness, together with the current values of the TEC, increases by a factor of two the agreement between calculated and measured foF2 values as compared with the variations from day to day. This allows foF2 to be defined in near-real time.     

Theoretical prediction of thermal diffusion coefficients for ternary hydrocarbon mixtures based on the irreversible thermodynamics theory

An accurate thermodiffusion model is of paramount importance to the petroleum industry for the prediction of the compositional variation in hydrocarbon reservoirs. Several theoretical models have been developed. Kempers and Firoozabadi models are the latest two models, which are not only applicable for binary mixtures but also for multi-component mixtures. In this paper, we applied the Firoozabadi model to a ternary hydrocarbon mixture of n-Dodecane, n-Butane and Methane with different mass fraction. It reveals that the accuracy of the thermal diffusion coefficients for a specific mixture of interest relies on the accuracy of the thermodynamic properties from equations of state, corresponding Fick's diffusion coefficients, and the thermal diffusion modeling.     

Variation of rain drop size distribution with rain rate at a few coastal and high altitude stations in southern peninsular India

Rain drop size distribution (DSD) was measured at four places in Southern India {Thiruvananthapuram, Kochi, Munnar and Sriharikota (SHAR)} using a Joss–Waldvogel (JW) impact type disdrometer. The data for each minute were corrected for dead time errors and rain rate was computed from the corrected data. The data for a whole month were then sorted according to rain rate (R) into several classes ranging from 0.1 to >100 mm/h. The average DSD in each class was computed, and the lognormal distribution function was fitted to the average. In all the cases, the function fitted the data very well. The fit parameters were found to have dependence on rain rate. The total number of drops (N_T), the geometric mean diameter (D_g) and the standard geometric deviation (σ) were also computed from the fit parameters. The standard geometric deviation (σ) was found to be more or less constant with rain rate at all the sites and in all months. The other two parameters (N_T and D_g) were found to vary exponentially with rain rate except in Munnar, a high altitude station. At Thiruvananthapuram, in most of the months, N_T increased exponentially with rain rate up to some value of R, which was different in different months, and then remained more or less constant or decrease slightly. In all cases, the variation of N_T and D_g was such that N_TD_g³ increased linearly with rain rate.