Integral-projection method and singularities of its application in mating shells with inconsistent parameters of approximation

We describe a numerical integral-projection method used by the authors for the approximate solution of systems of interrelated two-dimensional linear boundary-value problems in mechanics of composite shell systems. The method is based on discretization in each shell substructure of a two-dimensional problem along one of coordinates using a projection-grid variant of the Galerkin-Petrov method and its subsequent transformation to a system of ordinary differential equations; by integration and introduction of sought functions as unknown derivatives, the system is reduced to a system of integral equations being solved by the method of mechanical quadratures. The method is characterized by the fact that its application requires no additional conditions of conformity with discretization parameters of substructures being mated.     

Soft X-ray emission from radio Loops I and III compared

We examine X-ray maps of the whole sky covering energies from 0.1 to 6 keV. We model Loop I X-ray emission as being caused by an old supernova that exploded into an already warm interstellar medium. After comparison with Loop III we deduce that there may be a general temperature gradient in the gas as we move away from the plane in the northern galactic hemisphere.     

Mean winds of the mesosphere and lower thermosphere (60–110 km): A global distribution from radar systems (MF,Meteor, VHF)

During the last decade a large number of radars (～12) have been developed, which have produced substantial quantities of tidally-corrected mean winds data. The distribution of the radars is not global, but many areas are well covered: the Americas with Poker Flat (65°N), Saskatoon (52°N), Durham (43°N), Atlanta (34°N), Puerto Rico (18°N); Europe with Kiruna (68°), Garchy (47°N) and Monpazier (44°N); and Oceania with Christchurch (44°S), Adelaide (35°S), Townsville (20°S), and Kyoto (35°N). Zonal and meridional wind height-time cross-sections from $\text{60}\text{80}$ km (MF/Meteor Radar) to ～110 km have been prepared for the last 5–6 years. They are compared with cross-sections from CIRA-72 for zonal winds, and Groves (1969) for meridional winds.It is shown that while CIRA-72 is still a useful model for many purposes, significant differences exist between it and the new radar data. The latter demonstrate important seasonal, latitudinal, longitudinal and hemispheric variations. The new meridional cross-sections are of great value. The common features with Groves (1969) are the equatorward cells in summer near 85 km; however their strength (～10 ms^?1) and size are less. Systematic and somewhat different variations emerge at higher (?52°N) and middle (35–44°) latitudes.     

The contributions of the incoherent scatter radar technique to the development of thermospheric models

The contributions of the incoherent scatter radar technique to the development of thermospheric models is traced from the development of the radar technique in 1958. Emphasis is given to the qualitative information regarding thermospheric processes and behavior provided by the radar studies and the role that these results have played in the structural development of thermospheric models. The complementary nature of radar and satellite data in the development of recent models is stressed. In addition, a summary of pertinent radar developments over the past two years is presented. Primary among these are measurements made by high-latitude radars, multi-radar coordinated observations, the establishment of an incoherent scatter radar data base, and publication of a number of studies concerning high-latitude measurements, solar-cyle maximum results, long-term data sets, and lower thermosphere tides.     

Synthetic Environments for Simulated Missions

Synthetic environments offer Space Flight projects an opportunity to perform rapid, comprehensive, and rigorous modeling of the critical elements of a mission in order to compute quantitative measures of design performance, associated risk, and actual mission utility value. Significantly, these studies can be performed early in the mission cycle. These synthetic terrains are generated on parallel, high-performance computers and served to remote simulations at near-interactive speeds. The terrain creation uses a realistic sequence of physical phenomena such as cratering and dusting with parametric control of features such as surface roughness and rock density. Terrain resolution may be arbitrary but typically ranges from 0.01 to 10 meters. The terrain server has been used for two rover simulations, one using the actual Sojourner autonomy flight code, and the other a more general algorithm. Monte Carlo studies of rover designs interacting with synthetic environments were executed in parallel to quickly compute performance statistics and risk estimates.     

An investigation of small GOES flares with intense hard X-ray bursts

Most solar flare observations show that intense hard X-ray bursts come from large flares that have a large GOES classification (large peak 1 – 8 Å flux). This correlation, known as the “Big Flare Syndrome”, suggests that more intense flares tend to have harder spectra. We have observed 7 flares that are exceptions to this. These flares have small GOES classifications ranging from B1.4 to C5.5 and peak hard X-ray count rates similar to those often observed from M class flares. This paper examines the cause of this anomoly using the Yohkoh Soft X-Ray Telescope, Hard X-Ray Telescope, and Bragg Crystal Spectrometer. Two hypotheses are proposed for the exceptions: (1) flares with multiple magnetic loops and common footpoints, producing multiple hard X-ray emission regions and low density thermal plasma distributed over a large volume, and (2) high densities in the magnetic loops restricting the propagation of the non-thermal electrons in the loop after magnetic reconnection has occurred and suppressing chromospheric evaporation. Two of the flares support the first hypothesis. The other flares either have data missing or are too small to be properly analysed by the Yohkoh instruments.     

Tide-associated biological rhythms of some White Sea littoral invertebrates.

We report the results from two years of laboratory observations of the tide-associated rhythms of activity of White Sea intertidal invertebrates, Mya arenaria (Bivalvia) and Gammarus finmarchicus (Amphipoda). The tidal associated activity of these invertebrates could not be estimate as a clear circatidal clock. Gammarus activity could be phase shifted by a 0.5 h exposure to turbulent water twice a day for 2-3 days. Mya's rhythm could be changed by a single drainage of aquariums lasting about 15 min. This kind of timing system may be a relatively primitive evolution feature.     

Study of the radiation environment on MIR space station with SILEYE-2 experiment.

In this work we present preliminary results of nuclear composition measurements on board space station MIR obtained with SILEYE-2 particle telescope. SILEYE-2 was placed on MIR in 1997 and has been working since then. It consists of an array of 6 active silicon strip detectors which allow nuclear and energetic identification of cosmic rays in the energy range between approximately 30 and 200 MeV/n. The device is attached to an helmet and connected to an eye mask which shields the cosmonaut eyes from light and allow studies of the Light Flashes (LF) phenomenon. In addition to the study of the causes of LF, the device is used to perform real time long term radiation environment monitoring inside the MIR, performing measurements in solar quiet and active days.     

A low cost steerable radio-telescope

We present the technical characteristics of a low-cost radio telescope for solar/non solar observations at decimetric (1200–1700 MHz) and centimetric (2700 and 5000 MHz) wavelengths known as Brazilian Decimetric Array (BDA). The technical specifications of the antenna, tracking system, log-periodic feed, preamplifier and the frequency-synthesised receiver with a Single Side Band (SSB) video output of 2.5 MHz are given.