Abstract-Recent development in wireless technology enables communication between vehicles. The concept of Co-operative Adaptive Cruise Control (CACC) -which uses wireless communication between vehicles -aims at string stable behaviour in a platoon of vehicles. "String stability" means any non-zero position, speed, and acceleration errors of an individual vehicle in a string do not amplify when they propagate upstream. In this paper, we will discuss the string stability of CACC and evaluate its performance with various packet loss ratios, beacon sending frequencies and time headway in simulations. The simulation framework is built up with a controller prototype, a traffic simulator, and a network simulator.

Recent development in wireless technology enables communication between vehicles. The concept of cooperative adaptive cruise control (CACC)-which uses wireless communication between vehicles-aims at string stable behavior in a platoon of vehicles. "String stability" means any non-zero position, speed, and acceleration errors of an individual vehicle in a string do not amplify when they propagate upstream. In this article, we will discuss the string stability of CACC and evaluate its performance under varying packet loss ratios, beacon sending frequencies, and time headway settings in simulation experiments. The simulation framework is built up with a controller prototype, a traffic simulator, and a network simulator.

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Nano/ultrafine-grained (Nano/UFG) structure was obtained in Fe-17Cr-6Ni austenitic steel using a combination of severe cold deformation and reverse-transformation annealing. The microstructural evolution during severe cold reduction and annealing was studied to elucidate the effect of grain size on mechanical properties and strain hardening behavior. Austenitic steel with the smallest average grain size of ~220 nm was obtained and exhibited a good combination of high strength and high ductility when the cold reduction was ~75% and annealing was carried out at 700 ℃ for 20 s. The relationship between grain size and yield strength was in good agreement with Hall-Petch relationship until ~200 nm grain size. For coarse-grained steel, the strain hardening rate (SHR) plots comprised of 4 stages and the increase of SHR was attributed to deformation-induced martensite transformation (DIMT). While for Nano/UFG ASS, the SHR plots contained only 3 stages and the increase of SHR was attributed to the comprehensive effect of DIMT and twining.