Statistical properties of the most powerful solar and heliospheric disturbances

We present and discuss here the first version of a data base of extreme solar and heliospheric events. The data base contains now 87 extreme events mostly since 1940. An event is classified as extreme if one of the three critical parameters passed a lower limit. The critical parameters were the X-ray flux (parameter R), solar proton flux (parameter S) and geomagnetic disturbance level (parameter G). We find that the five strongest extreme events based on four variables (X-rays SEP, Dst, Ap) are completely separate except for the October 2003 event which is one the five most extreme events according to SEP, Dst and Ap. This underlines the special character of the October 2003 event, making it unique within 35 years. We also find that the events based on R and G are rather separate, indicating that the location of even extreme flares on the solar disk is important for geomagnetic effects. We also find that S = 3 events are not extreme in the same sense as R > 3 and G > 3 events, while S = 5 events are missing so far. This suggests that it might be useful to rescale the classification of SEP fluxes.     

Estimation of the determination accuracy of orbit parameters of the apophis asteroid from measurement results

An analysis of the existing astrometric and radar observations of the Apophis asteroid is performed. On the basis of this analysis, characteristics of future measurements of the asteroid orbit and limitation on their conduction are accepted. A proposed launching of a spacecraft to the asteroid in order to obtain high-accuracy measurements of its distance and radial velocity is also considered. Trajectories of the flight to the asteroid in 2012–2022 are studied. Estimates of the accuracy of the Apophis position determination at various sets of both available and planned measurements at various numbers of determined parameters are obtained. The method of estimating accuracy is similar to that used in [1] for the Vega project.     

Time variations of cosmic-ray helium isotopes with BESS-Polar I

The Balloon-borne Experiment with a Superconducting Spectrometer (BESS) is configured with a solenoidal superconducting magnet and a suite of precision particle detectors, including time-of-flight hodoscopes based on plastic scintillators, a silica-aerogel Cherenkov detector, and a high resolution tracking system with a central jet-type drift chamber. The charges of incident particles are determined from energy losses in the scintillators. Their magnetic rigidities (momentum/charge) are measured by reconstructing each particle trajectory in the magnetic field, and their velocities are obtained by using the time-of-flight system. Together, these measurements can accurately identify helium isotopes among the incoming cosmic-ray helium nuclei up to energies in the GeV per nucleon region. The BESS-Polar I instrument flew for 8.5 days over Antarctica from December 13th to December 21st, 2004. Its long-duration flight and large geometric acceptance allow the time variations of isotopic fluxes to be studied for the first time. The time variations of helium isotope fluxes are presented here for rigidities from 1.2 to 2.5 GV and results are compared to previously reported proton data and neutron monitor data.     

Difficulties in the study of cosmic radio noise absorption at 30 MHz using riometer at low latitude station,Kolhapur (Lat-16.8°N,Long-74.25°E)

A dual dipole antenna has been installed at low latitude station Kolhapur (Geographic 16.8°N, 74.25°E), Maharashtra, India for the study of cosmic radio noise absorption using Solid State Riometer (which operates at 30 MHz) during pre phase of 24th solar maxima. The aim for this type of study over Kolhapur was to know the response of lower (D region) ionosphere over low latitude by cosmic radio noise absorption using riometer technique during quite period as well as sudden ionospheric disturbances (SID). The observations are being taken for 3 years. Two different sites (∼40 km away from each other) were used for the installation of riometer equipment assuming minimum local noise. It is found that solar noise to cosmic radio noise hence resulting in signal saturation. The night time signal is relatively free of interference but sometimes local noise is responsible for spike-like signatures. Hence it is concluded that Kolhapur (a low latitude station) is not suitable for the study of cosmic radio noise absorption on 30 MHz with riometer and dual dipole antenna. Proper choice for operating frequency of riometer and antenna gain is suggested for low latitude use of this technique for ionospheric deviative and nondeviative absorption studies.     

Monthly mean foF2 model for an African low-latitude station and comparison with IRI

We have employed the hourly values of the ionospheric F-region critical frequency (foF2) obtained from Ouagadougou ionosonde, Burkina Faso (geographic coordinates 12° N, 1.8° W) during the interval of 1985–1995 (solar cycle 22) and solar radio flux of 10 cm wavelength (F10.7) to develop a local model (LM) for the African low-latitude station. The model was developed from regression analysis method, using the two-segmented regression analysis. We validated LM with foF2 data from Korhogo observatory, Cote d’Ivorie (geographical coordinates 9.3° N, 5.4° W). LM as well as the International Reference Ionosphere (IRI) agrees well with observations. LM gave some improvement on the IRI-predicted foF2 values at the sunrise (06 LT) at all solar flux levels and in all seasons except June solstice. The performance of the models at the representing the salient features of the equatorial foF2 was presented. Considering daytime and nighttime performances, LM and IRI are comparable in low solar activity (LSA), LM performed better than IRI in moderate solar activity (MSA), while IRI performed better than LM in high solar activity (HSA). CCIR has a root mean square error (r.m.s.e), which is only 0.10 MHz lower than that of LM while LM has r.m.s.e, which is about 0.05 MHz lower than that of URSI. In general, our result shows that performance of IRI, especially the CCIR option of the IRI, is quite comparable with the LM. The improved performance of IRI is a reflection of the numerous contributions of ionospheric physicists in the African region, larger volume of data for the IRI and the diversity of data sources, as well as the successes of the IRI task force activities.     

Aero-thermo-elastic Numerical Calculation and Analysis of Spinning Rocket

The application of computational fluid dynamics/computational solid method （CFD/CSM） on solving the aero-thermo-elastic problem of spinning rocket is introduced. Firstly, the aerodynamic coefficients of a rocket are calculated, and the results are compared with the available experimental data, which verified the accuracy of the CFD output. Then, analysis is carried using ANSYS Workbench multi-physics coupling platform, which includes fluid, thermal, and structural solvers. The results show that spinning causes a significant effect on the de formations and stresses. Furthermore, thermal stresses due to high temperature at the rocket warhead and tail edges have a dominated effect, even more than those produced by aerodynamic forces. Consequently, this important outcome should be taken into consideration during the rocket design stages.     

Extreme deviations of landing parameters for heavy aircraft

We estimate the statistic characteristics and extreme deviations of the state vector components for the Ilyushin Il 96–300 systems at automatic landing.     

Conductance of the channels and the knudsen paradox

In this paper, a physical model of gas flows through the channels is refined. The influence of gas absorbed by the walls of a channel on its conductance is shown. The experimentally obtained minimum on the channel conductance-pressure dependence (as the Knudsen paradox) is interpreted.     

On the hypothesis of adhesion

In this paper, the hypothesis of adhesion in fluid dynamics is analyzed and the field of its application is discussed.     

A synthetic aviation hydraulic fluid of new generation

The results of investigating a domestic synthetic hydraulic fluid of new generation are presented. By comparing with the existing domestic and foreign analogues, we specify the main advantages and disadvantages of this hydraulic fluid.