PLANR.: Planar Learning Autonomous Navigation Robot

PLANR is a self-contained robot capable of mapping a space and generating 2D floor plans of a building while identifying objects of interest. It runs Robot Operating System (ROS) and houses four main hardware components. An Arduino Mega board handles the navigation, while an NVIDIA Jetson TX2, holds most of the processing power and runs ROS. An Orbbec Astra Pro stereoscopic camera is used for recognition of doors, windows and outlets and the RPLiDAR A3 laser scanner is able to give depth for wall detection and dimension measurements. The robot is intended to operate autonomously and without constant human monitoring or intervention. The user is responsible for booting up the robot and extracting the map via SSH before shutting down

Direct simulation of ion beam induced stressing and amorphization of silicon

Using molecular dynamics (MD) simulation, we investigate the mechanical response of silicon to high dose ion-irradiation. We employ a realistic and efficient model to directly simulate ion beam induced amorphization. Structural properties of the amorphized sample are compared with experimental data and results of other simulation studies. We find the behavior of the irradiated material is related to the rate at which it can relax. Depending upon the ability to deform, we observe either the generation of a high compressive stress and subsequent expansion of the material, or generation of tensile stress and densification. We note that statistical material properties, such as radial distribution functions are not sufficient to differentiate between different densities of amorphous samples. For any reasonable deformation rate, we observe an expansion of the target upon amorphization in agreement with experimental observations. This is in contrast to simulations of quenching which usually result in denser structures relative to crystalline Si. We conclude that although there is substantial agreement between experimental measurements and most simulation results, the amorphous structures being investigated may have fundamental differences; the difference in density can be attributed to local defects within the amorphous network. Finally we show that annealing simulations of our amorphized samples can lead to a reduction of high energy local defects without a large scale rearrangement of the amorphous network. This supports the proposal that defects in amorphous silicon are analogous to those in crystalline silicon.Comment: 13 pages, 12 figure

Interstitial water patterns: A factor influencing the distributions of some lotic aquatic vascular macrophytes

The distributions of 9 species of aquatic vascular macrophytes were examined in relation to interstitial water patterns (based on temperature) in the beds of three northern Michigan (U.S.A.) streams. Ranunculus septentrionalis Poir., Caltha palustris L. and Nasturtium officinale R.Br. were associated with areas of groundwater discharge. Sparganium chlorocarpum Rydb., Veronica catenata Penn., Potamogeton filiformis Pers. and P. richardsonii (Benn.) Rydb. occurred most often at the downstream end of a hyporheic zone (corresponding to the foot of a riffle) where interstitial water was of surface origin. Sagittaria latifolia Willd. occurred where interstitial temperatures were cool; the water origin was not determined. Potamogeton gramineus L. occurred most often where interstitial temperatures were warm, primarily at the upstream ends and middles of hyporheic zones (heads of riffles) in areas of surface-water infiltration. Complex patterns of interstitial water movement and related physicochemical complexity combined with differences in plant requirements, in part, may determine observed local distributions.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/27221/1/0000225.pd

Formation of Organic Color Centers in Air-Suspended Carbon Nanotubes Using Vapor-Phase Reaction

Organic color centers in single-walled carbon nanotubes have demonstrated exceptional ability to generate single photons at room temperature in the telecom range. Combining the color centers with pristine air-suspended tubes would be desirable for improved performance, but all current synthetic methods occur in solution which makes them incompatible. Here we demonstrate formation of color centers in air-suspended nanotubes using vapor-phase reaction. Functionalization is directly verified on the same nanotubes by photoluminescence spectroscopy, with unambiguous statistics from more than a few thousand individual nanotubes. The color centers show a strong diameter-dependent emission intensity, which can be explained with a theoretical model for chemical reactivity taking into account strain along the tube curvature. We are also able to estimate the defect density by comparing the experiments with simulations based on a one-dimensional diffusion equation, whereas the analysis of diameter dependent peak energies gives insight to the nature of the dopant states. Time-resolved measurements show a longer lifetime for color center emission compared to E$_{11}$ exciton states. Our results highlight the influence of the tube structure on vapor-phase reactivity and emission properties, providing guidelines for development of high-performance near-infrared quantum light sources.Comment: 8 pages, 6 figure