摘要: With nonlinear optimal control method, the integrated control problem of ramp and route guidance for freeway network was studied, and an integrated optimal control model was put forward. In the model, the control objective is to minimize the total time spent (TTS) of freeway network, METANET model was taken as the process model of traffic flow, the minimum updating cycles of control variables were considered, and the numerical solution of the model was achieved by using particle swarm optimization (PSO) method. Simulation result shows that TTS is 3 376 veh·h under uncontrol, TTS is 3 005 veh·h under only ramp control, TTS is 2 768 veh·h under only route guidance, and TTS is 2 464 veh·h under integrated control. Obviously, the control effect of integrated control is optimal. 3 figs, 14 refs.更多>
摘要: X-ray computed tomography(CT) technology was adopted to scan the internal structures of AC-16, SMA-16 and OGFC-16 mixture specimens compacted using Marshall and Superpave gyratory compactor(SGC) methods. Digital image processing technology was adopted to analyze the spatial distribution of their internal air voids. The result shows that the distributions of air voids are not uniform in mixture specimens, and they vary greatly with the compacting styles and gradations of asphalt mixtures. Throughout the specimen height, air void percents are bigger on the top and at the bottom, and are smaller in the middles of the specimens compacted by SGC method, whereas the distribution variances are not marked for the specimens compacted by Marshall method. Throughout the cross sections of the specimens, air voids distribute more in the outside parts than in the middle parts for AC-16 and SMA-16 mixtures. 3 tAbs, 11 figs, 10 refs.更多>
