Non-equilibrium breakdown of quantum Hall state in graphene

In this report we experimentally probe the non-equilibrium breakdown of the quantum Hall state in monolayer graphene by injecting a high current density ($\sim$1A/m). The measured critical currents for dissipationless transport in the vicinity of integer filling factors show a dependence on filling factor. The breakdown can be understood in terms of inter Landau level (LL) scattering resulting from mixing of wavefunctions of different LLs. To further study the effect of transverse electric field, we measured the transverse resistance between the $\nu=2$ to $\nu=6$ plateau transition for different bias currents and observed an invariant point.Comment: to appear in PRB Rapi

Fabrication of Asymmetric Electrode Pairs with Nanometer Separation Made of Two Distinct Metals

We report a simple and reproducible method to fabricate two metallic electrodes made of different metals with a nanometer-sized gap. These electrodes are fabricated by defining a pair of gold electrodes lithographically and electrodepositing a second metal onto one of them. The method enables the fabrication of pairs of metallic electrodes that exhibit distinct magnetic properties or work functions. The utility of this technique is demonstrated by making single-electron tunneling devices incorporating 2-nm gold nanocrystals.Comment: 3 figures, 1 colo

Automated building footprint extraction from high resolution LIDAR DEM imagery

The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file.Title from title screen of research.pdf file viewed on (July 13, 2006)Includes bibliographical references.Thesis (M.S.) University of Missouri-Columbia 2005.Dissertations, Academic -- University of Missouri--Columbia -- Electrical engineering.Geographic Information Systems (GIS) are used in the fields of urban planning, environmental management, agriculture, transportation, utilities etc. because of their ability to provide geospatial information organized in multiple layers such as digital image basemap, land use zoning, political boundaries, parcel maps, land cover, road network, building footprints, utility networks (e.g. water, sewage and electricity), topography, and green space. Some urban features like roads and buildings change with the time and it is therefore necessary to update this information. The goal of this research is to provide a robust automated method to extract commercial buildings from the high resolution DEM data with high quality, accuracy, and detection rates. This processing strategy uses three different detectors which are fused to obtain a final output. Though multi-detector fusion has been used previously for satellite imagery, it is completely new for the DEM data. All three algorithms are developed using a fuzzy logic approach. The results of our algorithm show that we have obtained 82% correctness, 73% completeness and 65% quality pixel wise and 82% correctness, 97% completeness and 65% quality object wise for the tuning images and similar results for the test images. This approach can be expanded for the extraction of residential buildings which is left for future work