Organic chemistry in Titan's atmosphere: new data from laboratory simulations at low temperature.

Many experiments have already been carried out to simulate organic chemistry on Titan, the largest satellite of Saturn. They can provide fruitful information on the nature of minor organic constituents likely to be present in Titan's atmosphere, both in gas and aerosol phases. Indeed, all the organic compounds but one already detected in Titan's atmosphere have been identified in simulation experiments. The exception, C4N2, as well as other compounds expected in Titan from theoretical modeling, such as other N-organics, and polyynes, first of all C6H2, have never been detected in experimental simulation thus far. All these compounds are thermally unstable, and the temperature conditions used during the simulation experiments were not appropriate. We have recently started a new program of simulation experiments with temperature conditions close to that of Titan's environment. It also uses dedicated analytical techniques and procedures compatible with the analysis of organics only stable at low temperatures, as well solid products of low stability in the presence of O2 and H2O. Spark discharge of N2-CH4 gas mixtures was carried out at low temperature in the range 100-150 K. Products were analysed by FTIR, GC and GC-MS techniques. GC-peaks were identified by their mass spectrum, and, in most cases, by comparison of the retention time and mass spectrum with standard ones. We report here the first detection in Titan simulation experiments of C6H2 and HC5N. Their abundance is a few percent relative to C4H2 and HC3N, respectively. Preliminary data on the solid products indicate an elemental composition corresponding to (H11C11N)n. These results open new prospects in the modeling of Titan's haze making.     

An application of embedology to spatio-temporal pattern recognition

The theory of embedded time series is shown applicable for determining a reasonable lower bound on the length of test sequence required for accurate classification of moving objects. Sequentially recorded feature vectors of a moving object form a training trajectory in feature space. Each of the sequences of feature vector components is a time series, and under certain conditions, each of these time series has approximately the same fractal dimension. The embedding theorem may be applied to this fractal dimension to establish a sufficient number of observations to determine the feature space trajectory of the object. It is argued that this number is a reasonable lower bound on test sequence length for use in object classification. Experiments with data corresponding to five military vehicles (observed following a projected Lorenz trajectory on a viewing sphere) show that this bound is indeed adequate     

Space radiation quality factor investigations with “NAUSICAA”-device on board the “MIR” space station

The estimation of radiation quality factor in space flights is a serious problem of space dosimetry. The solution of this problem is based on LET-spectra measurements. The “NAUSICAA”-device installed on the “MIR” station has a detector with a large geometric factor, that gives the possibility of measuring LET-spectra with sufficient statistic in relatively short time interval and hence the corresponding Q. LET-spectra are accumulated through 24 hour periods and equivalent dose (H), absorbed dose (D), quality factor and flux (F) are measured every 10 minutes. The obtained data permit the estimate of the diurnal Q and Q in South Atlantic Anomaly. These values vary in the range of 1.4 – 2.2. The analysis of these values including their comparison with the calculated results is given in this paper.     

Temperature structure and dynamics of the middle atmosphere of Venus

The definitive data set for the mean thermal structure of the Venusian middle atmosphere is published for the first time. Some recent interim results on a modelling study to interpret the measured thermal field in terms of the global dynamics are also presented. These indicate that (a) the zonal winds on Venus fall to very low values above about 90 km, (b) there is a strong mid-latitude jet which circles the planet approximately every two days, (c) the observed solar tides are dominated by the semi-diurnal component, in agreement with theory.     

Computational intelligence and soft computing for spaceapplications

Systems using computational intelligence and soft computing have been successfully developed for many industrial and space applications. These systems seek to emulate the type of reasoning that humans perform when solving complex tasks. The field of soft computing, as defined by Zadeh-the inventor of fuzzy logic-encompasses fuzzy logic as well as other methodologies such as neural networks, genetic algorithms, and uncertainty management. It is expected that soft-computing techniques will eventually become as common and prevalent as traditional methods of computer science. This paper presents an overview of applications of fuzzy logic and soft computing to space projects. The role of fuzzy systems that can learn from experience to improve their performance is discussed. We present a report on applications of these adaptive systems to NASA space projects such as the orbital operations of the Space Shuttle, which include attitude control and rendezvous/docking operations. We also provide insights on the future of computational intelligence and soft computing and of their vast potential in industrial applications     

Batteries vs. alternatives for storing energy

Electric utilities need quickly-available sources of power for supplying expected and unexpected peak loads. Among useful sources have been the energy stored in water by pumping it to elevated storage reservoirs, in air compressed into underground chambers, and in batteries. A new power source, tBase-load nuclear and coal-fired steam plants generate off-peak energy for recharging the depleted storage facility. The aero-derived gas turbine, challenges the economics of these traditional energy-storage means. These turbines have been designed for aircraft where quick startup, rapid change in output power, and high reliability are essential. With a 1426°C (2600°F) turbine inlet temperature the available efficiencies are 42% in simple-cycle operation and 60% in a combined-cycle power plant. A recent 84-MW natural-gas-burning peak-power plant cost $204 per kW. Pacific Gas and Electric's Helmes River pumped-hydro plant had cost $656 per kW. The combined-cycle gas turbine plants, with their low manpower requirements, are producing power that costs less than power from nuclear power plants. We examine the performance and economics available from these new power sources     

Delta-electron emission in fast heavy ion atom collisions.

Biological damages such as mutations, chromosomal aberrations etc. are a consequence of biochemical changes mostly in the DNA. With ionizing radiation, these chemical changes are due to primary ionization events and secondary ionization effects caused by the primarily produced electrons. Differences in the biological response of densely ionizing radiation, like heavy charged particles, in comparison to sparsely ionizing radiation, such as X- or gamma-rays, are mainly due to the differences in the production of the so called delta-electrons. Therefore, the emission process of electrons i.e. the cross section for the primary ionization event as well as the energy and angular distribution of the emitted electrons should be understood in detail. The delta-electron emission processes occuring in fast heavy ion atom collisions are explained qualitatively. The different spectral structures of electron emission arising from either the target or the projectile are explained in terms of simple models of the kinetics of momentum transfer induced by the COULOMB forces. In collisions of very heavy ions with matter, high nuclear COULOMB forces are created. These forces lead to a strong polarization of the electronic states of the participated electrons. The effects of this polarization are discussed.     

Extreme starburst or central activity in X-ray luminous IRAS galaxies

ROSAT All Sky Survey observations of IRAS galaxies have revealed up to now a number of 10 optically non-Seyfert galaxies with X-ray (0.1–2.4) luminosities up to a few 10⁴³erg · s⁻¹ (Boller et al. 1992). The sources are brighter than previous detection limits of a few 10⁴¹erg · s⁻¹ as found by Stocke et al. (1991) or Green, Anderson and Ward (1992) for Einstein sources. The optical classification is based on follow-up observations which indicate clearly the non-Seyfert (LINER and HII region-like galaxies) nature. Our investigations reveal that galaxies classified as non-Seyferts on the basis of optical spectroscopy may reach exceptionally high X-ray luminosities which are similar to that of Seyfert galaxies. On the basis of the present observational material we suppose a hidden low luminosity AGN in the centre of these objects as the source of energy production. The objects are of interest when evaluating starburst versus central activity.     

A potentialgradient-conductivity-scanner for the investigation of effects leading to buoyancy-driven convection on continuous-flow-electrophoresis.

Continuous flow electrophoresis (CFE) is a mild and high-resolving method for the separation of sensitive biomolecules like peptides and proteins. The resolution is decreased by several effects, of which density gradients are important since they lead to buoyancy-driven convection. A tool for the measurement of physical quantities that cause the separation process, a potentialgradient/conductivity-scanner has been developed. With this PC-scanner consecutive potential- and concentration profiles can be measured inside the CFE-chamber. Local current densities and local joule heat yielding density gradients are calculated from the measurement data. With the PC-scanner the influence of gravity on separations by CFE can be evaluated more easily by the knowledge of the thermal and electrical conditions inside the separation slit.