Classical analogs for Rabi-oscillations, Ramsey-fringes, and spin-echo in Josephson junctions

We investigate the results of recently published experiments on the quantum behavior of Josephson circuits in terms of the classical modelling based on the resistively and capacitively-shunted (RCSJ) junction model. Our analysis shows evidence for a close analogy between the nonlinear behavior of a pulsed microwave-driven Josephson junction at low temperature and low dissipation and the experimental observations reported for the Josephson circuits. Specifically, we demonstrate that Rabi-oscillations, Ramsey-fringes, and spin-echo observations are not phenomena with a unique quantum interpretation. In fact, they are natural consequences of transients to phase-locking in classical nonlinear dynamics and can be observed in a purely classical model of a Josephson junction when the experimental recipe for the application of microwaves is followed and the experimental detection scheme followed. We therefore conclude that classical nonlinear dynamics can contribute to the understanding of relevant experimental observations of Josephson response to various microwave perturbations at very low temperature and low dissipation.Comment: 16 pages, 7 figure

RiverLand 2.0: Blending of Multiple User-defined Slopes in a Procedurally Modeled Terrain

This writing project attempts to improve on and add features to the current program called RiverLand originally designed and implemented by Dr. Soon Tee Teoh. I discuss the original methods used by RiverLand to create procedurally generated terrain. I then explore the weaknesses of the original RiverLand which include having only linear ridges and undesirable medial axis cells. I then tackle the problem of recurring patterns when texturizing a surface with very few textures. I propose how to solve these problems and explain the methods used to accomplish this. I discuss the user interfaces that were designed to accommodate the added features to RiverLand. I also discuss the open problems with the updated RiverLand

Worldsheet Instanton Corrections to the Kaluza-Klein Monopole

The Kaluza-Klein monopole is a well known object in both gravity and string theory, related by T-duality to a "smeared" NS5-brane which retains the isometry around the duality circle. As the true NS5-brane solution is localized at a point on the circle, duality implies that the Kaluza-Klein monopole should show some corresponding behavior. In this paper, we express the Kaluza-Klein monopole as a gauged linear sigma model in two dimensions and show that worldsheet instantons give corrections to its geometry. These corrections can be understood as a localization in "winding space" which could be probed by strings with winding charge around the circle.Comment: 20 pages, REVTeX, v2: minor equation correctio

Identifying and illustrating urban traffic congestion, mobility, and accessibility using a Gis

Urban congestion, accessibility, and mobility are important concerns affecting the quality of life in metropolitan areas. It is important that accessibility and mobility should not be compromised while developing strategies to alleviate congestion. The effects of traffic congestion include not only increase travel delays, which result in the increase of travel times, but also impacts energy consumption and air quality. All of these have detrimental effects on the quality of life. In order to develop strategies to alleviate urban congestion, it is necessary to first identify where and when congestion occurs--i.e., the spatial and temporal distribution of congestion. The objective of this research is to demonstrate the application of a geographic information system (GIS) to help identify and illustrate urban congestion, accessibility, and mobility. Definitions of mobility, accessibility, and congestion are presented as well as the advantages of using a GIS. A list of performance measures which are typically used to quantify these transportation functions are discussed. Data required to quantify the performance measures, their sources and integration within a GIS are discussed. Lastly GIS analyses used to quantify the performance measure are discussed. The performance measures used are: (1) non-recurring delay, (2) average vehicle occupancy, (3) business and employee accessibility to transit routes, (4) residential accessibility to transit routes, (5) Transit accessibility to areas of low automobile ownership, and finally (6) travel time. Specific example are presented to illustrate the application of GIS to evaluate the performance measures identified. In turn, these can be used to develop policies and operational strategies to address congestion (and potential congestion), mobility, and accessibility issues in urban areas. Conclusions are the GIS is a viable tool to assist planners and engineers to identify problem areas using already existing data sources