Economic Sustainability of Inner City Streets: A Collaborative Sustainable Asset Management Transportation System Model

The research team developed and created a sustainable asset management transportation system model, focusing on inner-city road conditions related to municipal asset allocation within three St. Louis, Missouri wards. To facilitate the research objectives, the team collaborated with Missouri constituents including the Missouri Department of Transportation (MoDOT), the City of St. Louis Street Department, local government officials, universities, and stakeholders. Selection criteria for roadways included roads, traffic, location, safety, utility, and demographics. A 45-block area was divided into six sections and roads were surveyed, photographed, and evaluated using The Transportation Engineers Association of Missouri’s Pavement Surface Evaluation and Rating (PASER). Necessary street repairs and costs of each repair were calculated using global mapping technology and historical cost data. Since aldermen decide street asset allocations, costs were allocated to each city ward district. These assessments, which were based on a technology-driven model, should assist in the construction of future financial models based on a need projection to dollars spent ratio per fiscal year. It is expected that this economic model will be implemented in the St. Louis Metropolitan Region and replicated by similar municipalities

Influence of copper on the electronic properties of amorphous chalcogenides

We have studied the influence of alloying copper with amorphous arsenic sulfide on the electronic properties of this material. In our computer-generated models, copper is found in two-fold near-linear and four-fold square-planar configurations, which apparently correspond to Cu(I) and Cu(II) oxidation states. The number of overcoordinated atoms, both arsenic and sulfur, grows with increasing concentration of copper. Overcoordinated sulfur is found in trigonal planar configuration, and overcoordinated (four-fold) arsenic is in tetrahedral configuration. Addition of copper suppresses the localization of lone-pair electrons on chalcogen atoms, and localized states at the top of the valence band are due to Cu 3d orbitals. Evidently, these additional Cu states, which are positioned at the same energies as the states due to ([As4]-)-([S_3]+) pairs, are responsible for masking photodarkening in Cu chalcogenides

Low-loss waveguides in ultrafast laser-deposited As(2)S(3) chalcogenide films

This paper was published in Journal of the Optical Society of America B and is made available as an electronic reprint with the permission of OSA. The paper can be found at the following URL on the OSA website: http://www.opticsinfobase.org/abstract.cfm?URI=josab-20-9-1844. Systematic or multiple reproduction or distribution to multiple locations via electronic or other means is prohibited and is subject to penalties under law.A. Zakery, Y. Ruan, A. V. Rode, M. Samoc, and B. Luther-Davie

High-performance Bragg gratings in chalcogenide rib waveguides written with a modified Sagnac interferometer

This paper was published in Journal of the Optical Society of America B-Optical Physics and is made available as an electronic reprint with the permission of OSA. The paper can be found at the following URL on the OSA website: http://www.opticsinfobase.org/abstract.cfm?URI=josab-23-7-1323. Systematic or multiple reproduction or distribution to multiple locations via electronic or other means is prohibited and is subject to penalties under law.Mehrdad Shokooh-Saremi, Vahid G. Ta'eed, Neil J. Baker, Ian C. M. Littler, David J. Moss, Benjamin J. Eggleton, Yinlan Ruan, and Barry Luther-Davie

Nonlinear Self-Confined Plasmonic Beams: Experimental Proof

International audienceControlling low power light beam self-confinement with ultrafast response time opens up opportunities for the development of signal processing in microdevices. The combination of a highly nonlinear medium with the tight confinement of plasmonic waves offers a viable but challenging configuration to reach this goal. In the present work, a beam propagating in a plasmonic structure that undergoes a strongly enhanced self-focusing effect is reported for the first time. The structure consists of a chalcogenide-based four-layer planar geometry engineered to limit plasmon propagation losses while exhibiting efficient Kerr self-focusing at moderate power. As expected from theory, only TM-polarized waves exhibit such a behavior. Different experimental arrangements are tested at telecom wavelengths and compared with simulations obtained from a dedicated model. The observed efficient beam reshaping takes place over a distance as low as 100 μm, which unlocks new perspectives for the development of integrated photonic devices