A Comparison of Two Approaches to Pure-Inertial and Doppler-Inertial Error Analysis

Error equations for inertial navigation systems are derived using a perturbation (or true frame) approach and a psi angle (or computer frame) approach in a manner which shows the underlying as sumptions and allows direct comparison of the two methods. The comparison is general since the analysis is not associated with any particular mechanization. Different definitions of velocity errors and misalignment angles result from the two methods of error analysis, and, consequently, have significance in testing and analysis of pure-inertial systems, Doppler-inertial systems, and inertially aided weapon delivery systems. Examples and numerical results are presented for a local-level north-pointing mechanization.     

DNA fragmentation in mammalian cells exposed to various light ions.

Elucidation of how effects of densely ionizing radiation at cellular level are linked to DNA damage is fundamental for a better understanding of the mechanisms leading to genomic damage (especially chromosome aberrations) and developing biophysical models to predict space radiation effects. We have investigated the DNA fragmentation patterns induced in Chinese hamster V79 cells by 31 keV/micrometer protons, 123 keV/micrometer helium-4 ions and gamma rays in the size range 0.023-5.7 Mbp, using calibrated Pulsed Field Gel Electrophoresis (PFGE). The frequency distributions of fragments induced by the charged particles were shifted towards smaller sizes with respect to that induced by comparable doses of gamma rays. The DSB yields, evaluated from the fragments induced in the size range studied, were higher for protons and helium ions than for gamma rays by a factor of about 1.9 and 1.2, respectively. However, these ratios do not adequately reflect the RBE observed on the same cells for inactivation and mutation induced by these beams. This is a further indication for the lack of correlation between the effects exerted at cellular level and the initial yield of DSB. The dependence on radiation quality of the fragmentation pattern suggests that it may have a role in damage repairability. We have analyzed these patterns with a "random breakage" model generalized in order to consider the initial non-random distribution of the DNA molecules. Our results suggest that a random breakage mechanism can describe with a reasonable approximation the DNA fragmentation induced by gamma rays, while the approximation is not so good for light ions, likely due to the interplay between ion tracks and chromatin organization at the loop level.     

Remote monitoring of aerosols from space

Using the four-channel teleradiometer “Micron” aboard the Orbital Stations “Salyut-4” and “Salyut-6” the brightness profiles were determined in the near-infrared spectral region up to the height of 60 km (in case of noctilucent clouds up to 80–85 km). Proceeding from the data above we obtained information on the global and vertical distributions of atmospheric aerosol, water vapour concentration and the optical properties of the noctilucent clouds.     

Remote sensing of natural formations from measurements of radiance coefficients

This paper is devoted to the consideration of some problems of remote sensing of natural formations using radiance coefficients in the narrow spectral invervals. The techniques for the determination of the most informative spectral intervals, as developed by the authors of the paper, are given and the results obtained are presented. The technique for obtaining the training sample of spectral radiance coefficients, with the help of a four-objective camera applied by the authors, is described. Some problems regarding the construction of a “universal” alphabet for classes of natural formations are discussed.     

Simulation and control of a 20-kHz spacecraft power system

A detailed computer representation of four Mapham inverters connected in a series-parallel arrangement has been implemented. System performance is illustrated by computer traces for the four Mapham inverters connected to a Litz cable with parallel resistance and DC receiver loads at the receiving end of the transmission cable. Methods of voltage control and load sharing between the inverters are demonstrated. The computer representation is used to design and demonstrate the advantages of a feedforward voltage-control strategy. It is shown that with a computer simulation of this type, the performance and control of spacecraft power systems can be investigated with relative ease and facility     

Remote sensing of the atmospheric from scientific stations “Salyut”

A review of the four-channel teleradiometer “Micron” calibration and data processing techniques has been presented. The sensor validation of the space-borne teleradiometer “Micron” was based on the following: the preflight absolute calibration with the state certificated standard, the secondary onboard standard (miniature filament lamp), the inflight measurements of the Moon's brightness. The procedure of the extinction coefficient determination from the daytime horizon profiles has been developed. The validity of the used techniques was estimated by carring out model calculations. An optimal measuring procedure has been recommended. The proposed simple techniques are used for processing the space measured horizon brightness data. The results have been compared with the earlier published ones.     

Supersonic expansion on non-equilibrium plasmas

In the supersonic expansion of an ionized gas, the dominant factor in describing the atomic processes is the recombination rate constant K_R. Several models describing the recombination process have been reviewed in some detail. It has been found that, depending on the adopted definition, different models will yield different values of K_R for the same electron temperature and number density. A comparison of experimentally and theoretically derived values for K_R has to be done with great care, as in the majority of the experiments K_R is determined from the measured rate of disappearance of free electrons. These measurements give the correct “decay coefficient”, but only in certain circumstances will it reduce to the correct recombination rate. In the light of the important role that K_R plays in any numerical solution of nonequilibrium expansion flow of plasmas, details of experiments on a 15-degree corner expansion flow of ionized argon are given. In these experiments the plasma flow which was generated by driving strong normal shock waves into quiescent argon was studied mainly by optical diagnostics. Using a dual-frequency laser interferometer, the plasma properties around a corner expansion were recorded. The analysis of the interferograms has yielded values for the recombination rate constant as a function of the plasma macroscopic properties. The range of shock Mach number, electron number density, temperature and initial channel pressure and temperature were as follows:

$\text{13 < M, < 19; 10}{}^{16}\text{< n, < 1.5 × 10}{}^{17}\text{cm}{}^{\mathrm{?3}}\text{; 9000°}\text{K}\text{< T < 13,000°}\text{K}\text{; 2.2 < p}{}_1\text{< 10}\text{torr}\text{; T}{}_1\text{? 300°}\text{K}\text{.}$

It was found that the theoretically predicted values for the three-body, electron-ion-electron collisional recombination rate are in good agreement with those measured gasdynamically in a well-defined flow. The measured flow quantities substantiate a previous analysis based on the method of characteristics.     

Dynamic systems as factors determining the structure,transformations and evolution of planets exemplified by the terrestrial planets

A more precise definition of planet is proposed based on the existence of dynamic planetary systems on it. Four basic planetary systems: the intraplanetary, the atmospheric, the magnetospheric and the biospheric one are discussed taking into account interactions of internal and external (cosmic) factors. The formation of distinct phases inside dynamic planetary systems is handled and the dissipative character of these phases is emphasized. The great importance of the formation and role of boundary layers between various phases is shown. Finally the exceptional significance of the action of some boundary layers as barriers is treated in some detail.     

Crystallization of germanium-silicon solid solution from the vapour phase in microgravity conditions

Mass transport has been investigated in the closed system Ge-Si-Br used for preparing germanium-silicon solid solution crystals by chemical transport reaction method in space. It has been shown that the experimental rate of mass transport may be analytically described in proposing a pure diffusion mechanism. In space, growth of needles and whiskers occured without practically formation of a polycrystalline layer characteristic of on-earth experiments.