We have fabricated 6.5 in. flexible full-color top-emission active matrix organic light-emitting diode display on a polyimide (PI) substrate driven amorphous indium gallium zinc oxide thin-film transistors (a-IGZO TFTs). The a-IGZO TFTs exhibited field-effect mobility (μFE) of 15.1 cm2/V s, subthreshold slope of 0.25 V/dec, threshold voltage (VTH) of 0.9 V. The electrical characteristics of TFTs on PI substrate, including a bias-stress instability after 1 h long gate bias at 15 V, were indistinguishable from those on glass substrate and showed high degree of spatial uniformity. TFT samples on 10 μm thick PI substrate withstood bending down to R=3 mm under tension and compression without any performance degradation.

The world largest flexible full color 6.5-inch active matrix organic light emitting diode (AMOLED) display with top emission mode on plastic film is demonstrated. The active matrix backplanes were fabricated using metal oxide thin film transistors (TFTs). The n-channel metal oxide TFTs on plastic film exhibited field-effect mobility of 17.8 cm 2 /Vs, threshold voltage of 0.4 V, on/off ratio of 1.1x 10 8 , and subthreshold slope of 0.34 V/dec. These TFT performance characteristics made it possible to integrate scan driver circuit, demux switching and compensation circuit on the panel. Bending tests were performed with TFT backplane samples to determine critical curvature radius to which the panel can be bent without TFT performance degradation. The results were compared with the calculations that took into account thicknesses and mechanical constants of flexible substrate and of thin-film layers in AMOLED device.

This study investigates the impacts of traffic signal timing optimization on vehicular fuel consumption and emissions at an urban corridor. The traffic signal optimization approach proposed integrates a TRANSIMS microscopic traffic simulator, the VT-Micro model (a microscopic emission and fuel consumption estimation model), and a genetic algorithm (GA)-based optimizer. An urban corridor consisting of four signalized intersections in Charlottesville, VA, USA, is used for a case study. The result of the case study is then compared with the best traffic signal timing plan generated by Synchro using the TRANSIMS microscopic traffic simulator. The proposed approach achieves much better performance than that of the best Synchro solution in terms of air quality, energy and mobility measures: 20% less network-wide fuel consumption, 8Á20% less vehicle emissions, and nearly 27% less vehicle-hours-traveled (VHT).

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This paper presents a detailed measurement study of short range communications between vehicles and between vehicles and roadside stations in a realistic highway scenario. We show the expected wireless communication characteristics in a driving environment and identify factors that significantly affect communication performance. We also illustrate the benefits of multi-hop communication in improving communication performance.

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A retrodirective antenna (RDA) array for wireless power transmission (WPT) is presented. Applications include the wireless charging of mobile phones and other handheld devices. The reported RDA defines an active high-power transmitter module which retrodirects a received beacon tone back to a mobile unit by circularly polarized (CP) free-space radiation. In addition, this RDA architecture uses a network of 4 sub-arrays, defined by a total of 16 radiating patch elements, in an effort to boost the transmit gain while also reducing the supporting RF hardware requirements when compared to a more conventional RDA. Measurements and simulations in the reactive near-field of the system are in agreement in terms of the tracking capabilities of the high-power CP-RDA. Power levels in excess of 27 dBm were measured at 2.4 GHz at a receiver module, and when this RF power was rectified, more than 350 mW at DC was observed. To the best knowledge of the authors, this is the first demonstration of a WPT system using a mixer-based analog-RDA. Previous low power demonstrations were more complex computer-controlled systems which did not offer any real-time tracking ability. Other applications for the proposed RDA include target tracking, sensor charging, and other WPT systems.