An analytic method to determine future close approaches between satellites   总被引：6，自引：0，他引：6  

Felix R. Hoots  Linda L. Crawford  Ronald L. Roehrich 《Celestial Mechanics and Dynamical Astronomy》1984,33(2):143-158

The calculation of the times of future close approaches between pairs of satellites has been formulated using analytical techniques. The resulting analytical equations are solved using numerical iterative techniques similar to solving Kepler's equation. A solution is obtained in a very efficient manner by use of a series of prefilters which eliminate many cases from further consideration. The method is valid for all values of eccentricities less than one and all relative geometries between the two orbits. This approach produces results in a very efficient and reliable manner.  相似文献   

Thirteenth Annual Geomorphology Symposium     

Ronald R. Dilamarter 《The Professional geographer》1983,35(1):102-102

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Some observations on the effect of ozone treatment on suspended particulate matter in seawater     

Hasong Pak  James Kitchen  Percy Donaghay  J. Ronald  V. Zaneveld 《Estuarine, Coastal and Shelf Science》1981,13(3):327-336

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Radioactive waste: A right to a decent burial     

Ronald W. Tank 《Environmental Geology》1983,5(4):167-168

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Mechanisms for trace metal enrichment at the surface microlayer in an estuarine salt marsh     

Leonard W Lion  Ronald W Harvey  James O Leckie 《Marine Chemistry》1982,11(3):235-244

The relative contributions of adsorption to particulate surfaces, complexation with surface-active organic ligands and uptake by micro-organisms were evaluated with respect to their importance in the surface microlayer enrichment (‘partitioning’) of Cd, Pb and Cu. The contributions of each process were inferred from field data in which partitioning of the dissolved and particulate forms of Cd, Pb and Cu, total and dissolved organic carbon, particles and total bacteria were observed. In the South San Francisco Bay estuary, particle enrichment appears to control trace metal partitioning. Trace metal association with the particulate phase and the levels of partitioning observed were in the order Pb > Cu > Cd and reflect the calculated equilibrium chemical speciation of these metals in computer-simulated seawater matrices.  相似文献   

Observed form and action of the magnetic field in flares     

Ronald L. Moore 《Solar physics》1982,113(1-2):121-124

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THE IMPACT OF FEDERAL LOCAL PUBLIC TRANSPORTATION ASSISTANCE UPON TRAVEL BEHAVIOR     

Ronald Briggs 《The Professional geographer》1980,32(3):316-325

Despite substantial amounts of federal assistance to local public transportation, ridership has declined considerably in the country as a whole since 1964, suggesting an ineffective government program. A city-by-city comparison of assistance received with changes in transit ridership shows that declines in transit usage were least in cities receiving the most federal aid, and greatest in cities receiving the least aid. This demonstrates that federal aid has had an impact upon travel behavior. Indeed, it is the single most important factor explaining differences between cities in travel behavior changes in the 1970's.  相似文献   

TALEMZANE: ALGERIAN IMPACT CRATER DETECTED ON SIR-A ORBITAL IMAGING RADAR     

John F. McHone  Ronald Greeley 《Meteoritics & planetary science》1987,22(3):253-264

In November, 1981, NASA's first Shuttle Imaging Radar mission (SIR-A) began producing maplike photographic strips of Earth scenes from orbital altitude. A Saharan radar image acquired over Algeria clearly delineates two sedimentary basins, Erg Occidental and Erg Oriental, separated by an elongated zone of exposed bedrock, the M'Zab Chebka. At the NE margin of the Chebka, rimrocks, slopes, and ejecta deposits of Talemzane meteorite impact crater appear as a distinct two km wide radar-bright ring. This unique circle of strong radar backscatter distinguishes the solitary impact structure from numerous dayas (similarly appearing karstic depressions) which characterize the region. The crater is prominant on radar, but is obscure on optically obtained satellite and aircraft images, as are partly buried fluvial drainage systems and fault-block traces developed in bedrocks of the Chebka. Radar detection of an annular drainage system indicates possible presence of a ring graben at the crater. Brightest radar signals on the image are cultural features at recently developed gas fields near Hassi er R'Mel.  相似文献   

An ion-exchange technique for concentrating ammonia from small volumes of seawater     

Ronald T. Riley  Michael C. Mix 《Marine Chemistry》1981,10(2):159-164

An ion-exchange technique was used to concentrate ammonia from seawater. Precipitation of bivalent cations, prior to concentration, reduced the variability of ammonia recovery from the ion-exchange column and lengthened column life. Analysis of the eluate was by the phenolhypochlorite reaction. The method was designed for use with small seawater samples (>10ml) and has the advantage that it can be adapted for use with small volumes of seawater with no loss in sensitivity. In a 10 ml seawater example NH₃-N concentrations of 10–150 μg l^?1 were accurately determined.  相似文献   

Beta-dispersion of low-frequency Rossby waves     

Paul S. Schopf  David L.T. Anderson  Ronald Smith 《Dynamics of Atmospheres and Oceans》1981,5(3):187-214

An investigation is made into the dispersion of oceanic internal Rossby waves at annual and semi-annual frequencies. Turning of the group velocity vector due to latitudinal variations in the radius of deformation cannot be neglected, particularly in basins as large as the Pacific. This turning allows disturbances to propagate from high lattitudes into the equatorial zone and distorts the solutions in the western part of the basin. For no mean flow, and a coastline aligned north-south, an almost exact focus of wave energy is found very close to the equator at a distance of just under $\text{πc/4ω}$ from the eastern boundary, where $\text{c}$ is the eigenspeed of a high-frequency internal wave mode, and ω is the angular frequency of the low-frequency wave being studied. The focus depends on a long meridional wavelength excited at the coast, and a frequency small compared with $\text{c/a}$, where $\text{a}$ is the radius of the Earth. For the lowest baroclinic mode and waves of annual period, this distance is about 12 000 km. Equivalence of the ray theory and the theory of equatorial meridional modes is demonstrated for the simple cases where the latter applies.The effects of mean currents and irregular coastlines are examined. Barotropic mean currents may change the turning latitude and ray shapes, inducing critical layers and enhancing reflection. Baroclinic mean currents are seen to affect the rays by simply changing the speed in proportion to the depth of the thermocline. As long as the mean currents are geostrophically balanced, no “effective beta” term from variations in the thermocline depth appears, in contrast to the topographic Rossby wave problem.  相似文献