Real-time Travel Time Estimation Using Macroscopic Traffic Flow Models

This paper presents the estimation of travel time on highways based on macroscopic modelling. The focus is on real-time values as compared to average or static values. The macroscopic models are used for distributed and time/space lumped settings and corresponding travel time estimation functions and algorithms are developed. The implications of these algorithms for the implementation of various incident management and traffic control strategies are also discussed

Flexible Low-cost Automated Scaled Highway (FLASH) Laboratory for Studies on Automated Highway Systems

This paper addresses the development of a flexible low-cost automated scale highway (FLASH) laboratory which is intended to serve as a catalyst for accelerating the development of many intelligent vehicle highway system (IVHS) concepts. It also highlights the significance of the laboratory for the research, evaluation, and testing of automated highway system (AHS) configurations, architectures, designs and technologies. This laboratory, using small scale standardized vehicles will serve as a test bed for the economical development and evaluation of various hardware, software, and management systems before full scale testing and deployment. The laboratory will provide the capability to test day and night, and will be immune to adverse weather conditions. It will be able to evaluate and test situations from various points of view including control, communication, routing, sensing, etc., which otherwise would be very expensive and dangerous-if human operators are involved-to test on test sites like Smart Road, a proposed testbed for ITS (IVHS) technology in Virginia. The development of this laboratory complements the development and utilization of the Smart Road, and is in harmony with the mission of the Center for Transportation Research

Experimental realization of a high-contrast grating based broadband quarter-wave plate

Cataloged from PDF version of article.Fabrication and experimental characterization of a broadband quarter-wave plate, which is based on two-dimensional and binary silicon high-contrast gratings, are reported. The quarter-wave plate feature is achieved by the utilization of a regime, in which the proposed grating structure exhibits nearly total and approximately equal transmission of transverse electric and transverse magnetic waves with a phase difference of approximately pi/2. The numerical and experimental results suggest a percent bandwidth of 42% and 33%, respectively, if the operation regime is defined as the range for which the conversion efficiency is higher than 0.9. A compact circular polarizer can be implemented by combining the grating with a linear polarizer. (C) 2012 Optical Society of Americ

Optimized Dipole Antennas on Photonic Band gap crystals

Cataloged from PDF version of article.Photonic band gap crystals have been used as a perfectly reflecting substrate for planar dipole antennas in the 12–15 GHz regime. The position, orientation, and driving frequency of the dipole antenna on the photonic band gap crystal surface, have been optimized for antenna performance and directionality. Virtually no radiated power is lost to the photonic crystal resulting in gains and radiation efficiencies larger than antennas on other conventional dielectric substrates. © 1995 American Institute of Physic

Resonant cavity enhanced detectors embedded in photonic crystals

Cataloged from PDF version of article.We report a resonant cavity enhanced (RCE) detector built around a three-dimensional photonic band gap crystal. The RCE detector was built by placing a monopole antenna within the localized modes of planar and boxlike defectstructures. The enhanced electric field around these defectstructures were then measured by a microwave detector and a network analyzer. We measured a power enhancement factor of 3450 for planar cavity structures. A Fabry–Perot cavity model was used to understand and predict resonant cavity enhancement in this structure. The tuning bandwidth of the RCE detector extends from 10.5 to 12.8 GHz, which corresponds to the full photonic band gap by the crystal. These RCE detectors have increased sensitivity and efficiency when compared to conventional detectors, and can be used for various applications. © 1998 American Institute of Physic

Quasimetallic silicon micromachined photonic crystals

Cataloged from PDF version of article.We report on fabrication of a layer-by-layer photonic crystal using highly doped silicon wafers processed by semiconductor micromachining techniques. The crystals, built using (100) silicon wafers, resulted in an upper stop band edge at 100 GHz. The transmission and defect characteristics of these structures were found to be analogous to metallic photonic crystals. We also investigated the effect of doping concentration on the defect characteristics. The experimental results agree well with predictions of the transfer matrix method simulations. (C) 2001 American Institute of Physics

High-speed GaAs-based resonant-cavity-enhanced 1.3 μm photodetector

Cataloged from PDF version of article.We report GaAs-based high-speed, resonant-cavity-enhanced, Schottky barrier internal photoemissionphotodiodes operating at 1.3 μm. The devices were fabricated by using a microwave-compatible fabrication process. Resonance of the cavity was tuned to 1.3 μm and a nine-fold enhancement was achieved in quantum efficiency. The photodiode had an experimental setup limited temporal response of 16 ps, corresponding to a 3 dB bandwidth of 20 GHz. © 2000 American Institute of Physic

Laser-micromachined Millimeter-wave Photonic band gap cavity structures

Cataloged from PDF version of article.We have used laser-micromachined alumina substrates to build a three-dimensional photonic band-gap crystal. The rod-based structure has a three-dimensional full photonic band gap between 90 and 100 GHz. The high resistivity of alumina results in a typical attenuation rate of 15 dB per unit cell within the band gap. By removing material, we have built defects which can be used as millimeter-wave cavity structures. The resulting quality ~Q! factors of the millimeter-wave cavity structures were as high as 1000 with a peak transmission of 10 dB below the incident signal. © 1995 American Institute of Physics

Photonic crystal-based resonant antenna with a very high directivity

Cataloged from PDF version of article.We investigate the radiation properties of an antenna that was formed by a hybrid combination of a monopole radiation source and a cavity built around a dielectric layer-by-layer three-dimensional photonic crystal. We measured a maximum directivity of 310, and a power enhancement of 180 at the resonant frequency of the cavity. We observed that the antenna has a narrow bandwidth determined by the cavity, where the resonant frequency can be tuned within the band gap of the photonic crystal. The measured radiation patterns agree well with our theoretical results. (C) 2000 American Institute of Physic

High-Speed High Effiency Large Area Resonant Cavity Enhanced p-I-n Photodiodes for Multimode Fiber Communications

Cataloged from PDF version of article.In this letter, we report AlGaAs–GaAs p-i-n photodiodes with a 3-dB bandwidth in excess of 10 GHz for devices as large as 60- m diameter. Resonant cavity enhanced photodetection is employed to improve quantum efficiency, resulting in more than 90% peak quantum efficiency at 850 nm