A standing wave Fourier transform spectrometer is realized. The spectrometer consists of an ultra thin and partially transparent photodetector and a tunable mirror. The incident light forms a standing wave in front of the mirror, which is sampled by the ultra thin optical detector. The thickness of the photodetector is significantly smaller than the wavelength of the incident light. The spectral information of the incident light is determined by the Fourier transform of the detector signal. The linear arrangement of the optical detector and the mirror enables the realization of spectrometer arrays and optical cameras with high spectral resolution. For the first time a complete optical model of the standing wave spectrometer is presented and compared with experimental results. The influence of the design of the optical detector on the performance of the spectrometer is discussed.
The introduction of Autonomous Vehicles (AVs) will have far-reaching effects on road traffic in cities and on highways.The implementation of Automated Highway Systems (AHS), possibly with a dedicated lane only for AVs, is believed to be a requirement to maximise the benefit from the advantages of AVs. We study the ramifications of an increasing percentage of AVs on the traffic system with and without the introduction of a dedicated AV lane on highways. We conduct an analytical evaluation of a simplified scenario and a macroscopic simulation of the city of Singapore under user equilibrium conditions with a realistic traffic demand. We present findings regarding average travel time, fuel consumption, throughput and road usage. Instead of only considering the highways, we also focus on the effects on the remaining road network. Our results show a reduction of average travel time and fuel consumption as a result of increasing the portion of AVs in the system. We show that the introduction of an AV lane is not beneficial in terms of average commute time. Examining the effects of the AV population only, however, the AV lane provides a considerable reduction of travel time (≈ 25%) at the price of delaying conventional vehicles (≈ 7%). Furthermore a notable shift of travel demand away from the highways towards major and small roads is noticed in early stages of AV penetration of the system. Finally, our findings show that after a certain threshold percentage of AVs the differences between AV and no AV lane scenarios become negligible.
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