Synthetic vision for enhancing poor visibility flight operations

Visibility is important for the pilot controlling an aircraft in flight conditions close to the ground, particularly when landing. Therefore, poor visibility yields a great restriction for aircraft operations. Restrictions exist for landing sites which are equipped with facilities providing a landing approach aid like ILS since a minimum is required for visibility. For landing sites providing no approach aids, restrictions are much more severe. This holds even if aircraft are equipped with modern instrumentation and navigation devices. The natural view of the pilot is dependent on various meteorological conditions like darkness, dust, fog, rain etc. The degradation in view caused by these conditions can be compensated for partially or even completely by technical means providing artificial vision cues. Such technical means may be based on radar or optical sensor information. Concepts which employ these techniques are known as “Synthetic Visual Systems” or “Enhanced Visual Systems,” . The present paper is concerned with computer generated vision as a further technique providing visual cues for the pilot. Computer generated vision may be used in combination with the aforementioned sensor based techniques. Thus, it is possible to compensate for limitations which sensor based visual systems have in providing sufficient visibility range or in generating a normal looking image. In addition, computer generated imagery has the potential providing additional information to the pilot for controlling the flight path or for warning purposes. This potential can yield improved and/or more information as compared with the natural view when looking out of the cockpit window     

Fuel cell technology status

Several major fuel cell projects and their status are described. The fuel cell types discussed are phosphoric acid, molten carbonate, solid oxide, and polymer. One of the technologies is very close to commercialization. Two others offer the possibility for higher efficiency and large capacity electric generation using coal. Still another may be the answer to the key issues facing the transportation sector     

Formation of bioorganic compounds in simulated planetary atmospheres by high energy particles or photons.

Various types of organic compounds have been detected in Jupiter, Titan, and cometary coma. It is probable that organic compounds were formed in primitive Earth and Mars atmospheres. Cosmic rays and solar UV are believed to be two major energy sources for organic formation in space. We examined energetics of organic formation in simulated planetary atmospheres. Gas mixtures including a C-source (carbon monoxide or methane) and a N-source (nitrogen or ammonia) was irradiated with the followings: High energy protons or electrons from accelerators, gamma-rays from 60Co, UV light from a deuterium lamp, and soft X-rays or UV light from an electron synchrotron. Amino acids were detected in the products of particles, gamma-rays and soft X-rays irradiation from each gas mixture examined. UV light gave, however, no amino acid precursors in the gas mixture of carbon monoxide, nitrogen and nitrogen. It gave only a trace of them in the gas mixture of carbon monoxide, ammonia and water or that of methane, nitrogen and water. Yield of amino acid precursors by photons greatly depended on their wavelength. These results suggest that nitrogen-containing organic compounds like amino acid precursors were formed chiefly with high energy particles, not UV photons, in Titan or primitive Earth/Mars atmospheres where ammonia is not available as a predominant N-source.     

Target detection and tracking with HF radar using reciprocal SARtechniques

Sustained research and development at Memorial University of Newfoundland has led to an operational High Frequency Ground Wave Radar (HF-GWR) system for coastal surveillance. This radar system has demonstrated over-the-horizon detection of targets such as vessels, ice hazards and low-flying aircraft, and performed ocean parameter measurements over a large area. The industrial developers of offshore hydrocarbon reserves in ice infested regions have an urgent requirement for the long range detection and tracking of icebergs from their production platforms. However, due to space restrictions, a rig- or ship-based system can only accommodate a compact antenna array. The uniform trajectory and low velocity of icebergs is ideal for Reciprocal Synthetic Aperture Radar (RSAR) processing with long target dwell times. The proven ice detection capability of HF-GWR systems, coupled with the compact antennas suggested by the RSAR technique, can be used to develop a rig- or ship-based all-weather surveillance device for ice hazards. It is also anticipated that the results of this research will allow the use of shorter antenna arrays for many other applications. Preliminary results using real data from the operational HF-GWR system are presented     

Infrared spectrometer PFS for the Mars 94 orbiter

Thin films containing a mixture of aliphatic (glycine) and aromatic (tryptophan or tyrosine) amino acids were exposed to a vacuum ultraviolet radiation (VUV) with wavelenghts 100–200 nm. Dipeptides (glycyl-tryptophan and glycyl-tyrosine) were synthesized in these conditions. We compared the actions of VUV and γ-radiation. Polymerization is an essential step in prebiological evolution and we have shown that this stage probably occured over an early Solar system history.     

Heavy-ion induced genetic changes and evolution processes.

On Moon and Mars, there will be more galactic cosmic rays and higher radiation doses than on earth. Our experimental studies showed that heavy ion radiation can effectively cause mutation and chromosome aberrations and that high-LET heavy-ion induced mutants can be irreversible. Chromosome translocations and deletions are common in cells irradiated by heavy particles, and ionizing radiations are effective in causing hyperploidy. The importance of the genetic changes in the evolution of life is an interesting question. Through evolution, there is an increase of DNA content in cells from lower forms of life to higher organisms. The DNA content, however, reached a plateau in vertebrates. By increasing DNA content, there can be an increase of information in the cell. For a given DNA content, the quality of information can be changed by rearranging the DNA. Because radiation can cause hyperploidy, an increase of DNA content in cells, and can induce DNA rearrangement, it is likely that the evolution of life on Mars will be effected by its radiation environment. A simple analysis shows that the radiation level on Mars may cause a mutation frequency comparable to that of the spontaneous mutation rate on Earth. To the extent that mutation plays a role in adaptation, radiation alone on Mars may thus provide sufficient mutation for the evolution of life.     

Evolution of the Martian water cycle.

The current Martian water cycle is extremely asymmetric, with large amounts of vapor subliming off a permanent north polar water ice cap in northern summer, but with no apparent major source of water vapor in the southern hemisphere. Detailed simulations of this process with a three-dimensional circulation model indicate that the summertime interhemispheric exchange (Hadley cell) is very much stronger than transport by eddies in other seasons. As a result, water ice would be distributed globally were it not for the buffering action of regolith soil adsorption which limits the net flux of water vapor off the north polar cap to amounts that are insignificant even on the scale of thousands of years. It has been suggested that the polar layered deposits are the result of exchange on these long time scales, driven by changes in Martian orbital parameters. We therefore are conducting simulations to test the effect of varied orbital parameters on the Martian water cycle. We find that when the perihelion summer pole is charged with a polar water ice cap, large quantities of water are quickly transfered to the aphelion summer pole, setting up an annual cycle that resembles the present one. Thus, the adsorptivity of the Martian regolith may be in the narrow range where it can limit net transport from the aphelion but not the perihelion pole.     

Monte Carlo track structure studies of energy deposition and calculation of initial DSB and RBE.

Estimation of exposure due to environmental and other sources of radiations of high-LET and low-LET is of interest in radiobiology and radiation protection for risk assessment. To account for the differences in effectiveness of different types of radiations various parameters have been used. However, the relative inadequacy of the commonly used parameters, including dose, fluence, linear energy transfer, lineal energy, specific energy and quality factor, has been made manifest by the biological importance of the microscopic track structure and primary modes of interaction. Monte Carlo track structure simulations have been used to calculate the frequency of energy deposition by radiations of high- and low-LET in target sizes similar to DNA and higher order genomic structure. Tracks of monoenergetic heavy ions and electrons were constructed by following the molecular interaction-by-interaction histories of the particles down to 10 eV. Subsequently, geometrical models of these assumed biological targets were randomly exposed to the radiation tracks and the frequency of energy depositions obtained were normalized to unit dose in unit density liquid water (l0(3) kg m-3). From these data and a more sophisticated model of the DNA, absolute yields of both single- and double-strand breaks expressed in number of breaks per dalton per Gray were obtained and compared with the measured yields. The relative biological effectiveness (RBE) for energy depositions in cylindrical targets has been calculated using 100 keV electrons as the reference radiation assuming the electron track-ends contribution is similar to that in 250 kV X-ray or Co60 gamma-ray irradiations.     

Fuel cell status, 1994

The high efficiency environmental benefits and other attributes of fuel cells have attracted world-wide attention to the technology. Approximately 250 phosphoric acid fuel cell (PAFC) power units, 35 molten carbonate fuel cell (MCFC) stacks, and 12 solid oxide fuel cell (SOFC) modules have been or are being operated. Total capacity installed or operating is close to 45 MW. Fuel cell development has progressed to where complete power plants have reached nearly 16,000 operating hours and this continues to increase. Developers in the U.S. and Japan have embarked on extensive government and private programs to commercialize the technology in those countries and abroad. By mid-1994, the U.S. sold and shipped to other countries at least 33 PAFC 200 kW plants, 20 675 kW PAFC stacks, two SOFC 25 kW modules, and one MCFC system. Additional units have been produced for the domestic market. There is intense interest in Japan where there are very stringent environmental regulations and fuel prices are high. The fuel cell can respond with its combined attributes of low emissions and relative high efficiency. In Europe, the environmental cleanliness of fuel cell power units holds the promise of preserving the quality of life, motivating support and development of the technology. Canada and Australia have spawned important development programs. Interest continues to increase in other parts of the world. The author reviews the 1994 status and outlines the future development trends in this area     

On small active region filaments,fibrils and surges

High resolution Hα images and magnetograms (0.2 arc s) of an active region were obtained in alternating time series at 42 s cadences using the Swedish 1-m Solar Telescope on 2004 August 21. The Hα filtergrams reveal an active region filament and surges consisting of thread-like structures which have widths similar to the widths of chromospheric fibrils, both recorded down to the resolution limit in the best images. All observed structures in the active region appear highly dynamic. Fibrils show counterstreaming strongly resembling the counterstreaming threads in filaments.