Numerical determination of Lissajous trajectories in the restricted three-body problem

In previous studies, Lissajous trajectories associated with the collinear libration points in the restricted three-body problem have been successfully computed analytically to at least third-order. Those approximations are utilized to determine such trajectories numerically for an arbitrary, predetermined number of revolutions in the rotating frame, for the case of circular primary motion. The numerical approach first identifies target positions at specified intervals along the trajectory and locates a continuous path through those points with velocity discontinuities. Then the v are simultaneously reduced in an iterative process. Such trajectories have been constructed in various primary systems, for a wide range of orbit sizes and a large number of revolutions.     

Raman and SEM analysis of a biocolonised hot spring travertine terrace in Svalbard,Norway

Background  

A profile across 8 layers from a fossil travertine terrace from a low temperature geothermal spring located in Svalbard, Norway has been studied using both Raman spectroscopy and SEM (Scanning Electron Microscopy) techniques to identify minerals and organic life signals.     

Calibration of soil heat flux transducers

Summary Soil heat flux transducer calibration, according to theory, is influenced by the thermal conductivity difference between the transducer and the calibration medium and the geometry of the transducer. This study was conducted to compare the influence of these parameters on the calibration factors of two types of commercial soil heat flux transducers with different material thermal conductivities and different geometries. A theoretical calibration equation was developed and evaluated. Calibrations of 14 transducers representing two commercial types were conducted in the laboratory using steady-state conductive methods over a range of heat fluxes from 40 W/m² to 200 W/m². The calibration medium was dry and saturated sand with a thermal conductivity varying from 0.3 to 3 W m^–1°C^–1. The mean calibration factor for one type of transducer was 12% lower than the mean manufacturer's calibration factor instead of the 26 to 36% lower value predicted by theory. The other type of transducer had a mean calibration factor 7% greater than the mean manufacturer's calibration factor in contrast to the 1 to 11% larger value predicted from theory. The computed geometric factors were 1.07 and 0.89 for the circular and square transducers, respectively. These factors were less than the theoretical value of 1.70 for each shape of transducer but similar to experimental values of 1.02 to 1.31 from previous studies reported in the literature. The thermal conductivity of the calibration medium and the geometry of the transducer affects the calibration factors of soil heat flux transducers, basically according to theory.Contribution from USDA-Agricultural Research Service, Southern Plains Area.With 4 Figures