Optimum Windows for Image Registration

Two-dimensional cross-correlation techniques are applied to the problem of image registration under the assumption of small geometric distortion. Optimum window functions are derived for two performance measures of interest: peak-to-sidelobe ratio and mean-square registration error. The latter is examined in terms of the contribution caused by noise and the contribution caused by geometric distortion. A generalized Lagrange multiplier approach is used to derive approximate solutions assuming random images. The case of Gaussian autocorrelation functions is examined in detail. Results of applying the theoretically derived window functions to real data are presented, showing significant improvement in correlator performance.     

The telemedicine frontier: going the extra mile

Telemedicine has the potential to have a greater impact on the future of medicine than any other modality and will profoundly alter the medical landscape of the twenty-first century. In the most remote areas, it can bring high-quality health care where none is now available. In global health care, it can enhance and standardize the quality of medical care, including developing countries. In the realm of space flight, it can provide a lifeline to medical expertise and monitoring. Through its mobility, it can provide urgently needed health care in instances of natural disaster. However, a number of challenges exist in its coordination and implementation on a global scale, specifically in the international and remote disaster scenarios. In the area of spaceflight, telemedicine capability will remain a consultation/information ‘lifeline’, but additional onboard medical capability and expertise will become crucial complements as missions become more advanced and remote from Earth.     

Representations of solar EUV fluxes for aeronomical applications

The development of significantly improved representations of solar EUV inputs for computer-aided investigations of the terrestrial thermosphere and ionosphere has become attractive particularly for the present solar cycle which has been covered by reasonably complete and continuous EUV observations from the AE-E Satellite. These representations try to satisfy some rather incongruous $\text{requirements of spectral detail}$, regarding (a) the strong wavelength-dependence in the $\text{terrestrial}$ atmospheric cross sections of the various types of EUV photon interactions, (b) the great differences in the relative amplitudes of the various types of variations in the full-disk fluxes of $\text{solar}$ emissions at different wavelengths, and (c) the persisting desire to use only a $\text{small number of daily indices}$ as actual input variables for computational models supposed to cover the entire EUV wavelength range (remembering the great success of empirical thermospheric models using only two indices). These general physical and specific aeronomical demands indeed outline a very difficult task. The present study, based mainly on AE-E satellite observations during 1976–1979, represents an exploratory step, only clarifying some important developmental aspects, without recommending any specific formulations for immediately practicable adoption in aeronomical modelling at this time.     

Direct observation of charge state abundances of energetic He,C, O,and Fe emitted in solar flares

The ionic charge states of helium, carbon, oxygen, and iron have been determined for three solar particle enhancements by an electrostatic deflection analyzer, which is combined with a thin window proportional counter dE/dX vs. E system. The observations are obtained during the periods September 23 to 29, 1978, June 6 to 8, 1979, and September 15 to 26, 1979, with an instrument onboard the ISEE-3 spacecraft. The mean ionic charge states for He, C, and oxygen exhibit a high degree of ionization with values of Q = 2, 6, and 7.2, respectively. The charge state of iron is near 13 charge units. Variations from flare to flare and within the September 23, 1978 flare are small. The most surprising feature of the charge state measurement is the observation of a small (～10%) but finite contribution of singly ionized helium.     

Solar maximum mission experiment: Early results from the soft X-ray polychromator experiment

The X-Ray Polychromator experiment has been in operation on the SMM satellite for over three months. It is observing flares and active regions in the wavelength range 1Å to 23Å using a number of different modes. These include polychromatic imaging, high resolution line profiles, high dispersion spectra, and light curves with high time-resolution. Data are described together with some of the preliminary analysis and interpretation.     

Jikiken(EXOS-B) observation of siple transmissions

A Japanese magnetospheric satellite Jikiken (EXOS-B) was used to observe Siple transmissions and VLF emissions triggered by the Siple signals. Energetic particle fluxes were also observed at the same time. The first experiments were made during July, August and September in 1979 and the second experiments were made during December in 1979 and January in 1980. The Siple triggered emissions were observed in August. This report reviews the preliminary results.     

Fuel cell status: 1996

The technology of fuel cells is heating up. A world that, ten years ago, was unaware of the concept can now witness approximately 200 fuel cell units operating in 15 countries. Energy planners and decision makers are becoming aware that, in addition to a continual increase in installations, the reliability of early commercial units is outstanding and the cost is dropping. They have begun to ask whether fuel cells might fit into their future. While the fuel cell concept is simple, determining which type of fuel cell to consider may prove taxing. The multiplicity of fuel cells and their development programs, coupled with the amount of subject material and claims-versus-reality, may seem overwhelming. Fuel cell commercialization activities in North America are the focus of five manufacturers that are developing four types [fuel cells are typed by electrolyte: the 200°C phosphoric acid (PAFC); the 80°C proton exchange membrane (PEM); the 650°C molten carbonate (MCFC); and the 1,000°C solid oxide (SOFC) fuel cells]. Each fuel cell promises the attractive combination of fairly high efficiency and superior environmental performance compared to the presently available fossil-fueled electric generation technologies. As a result, fuel cells are particularly easy to site. There are additional advantages such as: excellent availability; electrical VAR control; quick ramp rate; remote/unattended operation; and redundancy when multiple units are installed. After earlier success in space, fuel cells are being applied to the commercial sector as on-site cogeneration units mostly fueled by natural gas. They are being considered for larger distributed generators (natural gas) and for vehicular power plants (methanol)