Tools and Algorithms for Sampling in Extreme Terrains

Extreme-terrain robots such as JPL’s Axel rover are enabling access to new and exciting science opportunities. The goal of this mini-program was to develop a compact sampling instrument for Axel. Over the summer of 2012, a small group of students designed, built, and tested prototype sampling devices. Nikola Georgiev created a versatile four-degree-of-freedom scoop, which can acquire up to 4 different samples in clean self-sealing containers. Hima Hassenruck-Gudipati studied percussive scooping, and prototyped a percussive scoop that takes advantage Axel’s independent body rotation to acquire samples. Kristen Holtz and Yifei Huang collaborated on a pneumatic sampling system, which uses a puff of air to propel loose grains into flexible tubing, and separates the grains into an interchangeable sample container. Each of these sampling systems has been demonstrated, and each proved useful for different conditions. In turn, the students gained valuable design experience and the opportunity to work alongside a number of experts in various fields

Optical and electron-energy-loss studies of the monomeric and dimeric phases of decamethylferrocenium tetracyanoquinodimethanide, (DMeFc)(TCNQ)

Journal ArticleThe optical properties of the two crystallographic phases of 1:l decaniethylferrocenium tetracyanoauinodimethanide, (DMeFc)(TCNQ), have been measured from 0.1 to 10 eV. One phase consists of isolated paramagnetic TCNQ anion monomers while the other contains isolated diamagnetic dimers. The spectrum of the monomeric phase exhibits a strong localized monomer exciton which is not normally observed in solid TCNQ salts, while the dimeric phase shows a charge-transfer excitation as well as a shifted local exciton. From the frequency- dependent conductivity of the dimeric phase the effective on-site Coulomb interaction and the transfer matrix element are measured to be 1.0 and 0.27 eV, respectively. The infrared absorption spectrum of the dimeric phase shows an unusual activity of the symmetric phonon modes due to the interaction of these modes with the radical electron, whereas in the monomeric phase only normally infrared active phonons are observed. In electron-energy-loss measurements an anomalous momentum dependence of the line shape of the monomeric exciton was observed. This result is attributed to a dielectric effect caused by the decrease in strength of local excitons with increasing momentum

Simulating the outer layers of rapidly rotating stars

This paper presents the results of a set of radiative hydrodynamic (RHD) simulations of convection in the near-surface regions of a rapidly rotating star. The simulations use microphysics consistent with stellar models, and include the effects of realistic convection and radiative transfer. We find that the overall effect of rotation is to reduce the strength of turbulence. The combination of rotation and radiative cooling creates a zonal velocity profile in which the motion of fluid parcels near the surface is independent of rotation. Their motion is controlled by the strong up and down flows generated by radiative cooling. The fluid parcels in the deeper layers, on the other hand, are controlled by rotation.Comment: 9 pages, 9 Figues and one tabl

Simulating the Outer Layers of Rapidly Rotating Stars

This paper presents the results of a set of radiative hydrodynamic (RHD) simulations of convection in the near-surface regions of a rapidly rotating star. The simulations use microphysics consistent with stellar models, and include the effects of realistic convection and radiative transfer. We find that the overall effect of rotation is to reduce the strength of turbulence. The combination of rotation and radiative cooling creates a zonal velocity profile in which the motion of fluid parcels near the surface is independent of rotation. Their motion is controlled by the strong up and down flows generated by radiative cooling. The fluid parcels in the deeper layers, on the other hand, are controlled by rotation

Tools and Algorithms for Sampling in Extreme Terrains

Extreme-terrain robots such as JPL’s Axel rover are enabling access to new and exciting science opportunities. The goal of this mini-program was to develop a compact sampling instrument for Axel. Over the summer of 2012, a small group of students designed, built, and tested prototype sampling devices. Nikola Georgiev created a versatile four-degree-of-freedom scoop, which can acquire up to 4 different samples in clean self-sealing containers. Hima Hassenruck-Gudipati studied percussive scooping, and prototyped a percussive scoop that takes advantage Axel’s independent body rotation to acquire samples. Kristen Holtz and Yifei Huang collaborated on a pneumatic sampling system, which uses a puff of air to propel loose grains into flexible tubing, and separates the grains into an interchangeable sample container. Each of these sampling systems has been demonstrated, and each proved useful for different conditions. In turn, the students gained valuable design experience and the opportunity to work alongside a number of experts in various fields