Showing papers by "Yiu-Yin Lee published in 2020"
15 Aug 2020
TL;DR: The model application is extended to handle the difficult residual queue scenario and it is found that the proposed model can optimize the traffic signal settings in cases where there are short initial residual queues.
Abstract: In the lane-based signal optimization model, permitted turn directions in the form of lane markings that guide road users to turn at an intersection are optimized with traffic signal settings. The spatial queue requirements of approach lanes should be considered to avoid the overdesigning of the cycle, effective red, and effective green durations. The point-queue system employed in the conventional modeling approach is unrealistic in many practical situations. Overflow conditions cannot be modeled accurately, while vehicle queues are accumulated that block back upstream intersections. In a previous study, a method was developed to manually refine the traffic signal settings by using the results of lane-based optimization. However, the method was inefficient. In the present study, new design constraint sets are proposed to control the effective red and effective green durations, such that traffic enters the road lanes without overflow. The reduced cycle times discharge the accumulated vehicles more frequently. Moreover, queue spillback and residual queues can be avoided. One of the most complicated four-arm intersections in Hong Kong is considered as a case study for demonstration. The existing traffic signal settings are ineffective for controlling the observed traffic demand, and overflow occurs in short lanes. The optimized traffic signal settings applied to the proposed optimization algorithm effectively avoided traffic overflow. The resultant queuing dynamics are simulated using TRANSYT 15 Cell Transmission Model (CTM) to verify the proposed model. The model application is extended to handle the difficult residual queue scenario. It is found that the proposed model can optimize the traffic signal settings in cases where there are short initial residual queues.
5 citations
02 Dec 2020
TL;DR: In this article, the free vibration analysis of a nonlinear structural-acoustic system with non-rigid boundaries is addressed, and the effect of cavity boundary on the resonant frequencies of the nonlinear system is examined.
Abstract: This study addresses the free vibration analysis of nonlinear structural-acoustic system with non-rigid boundaries. In practice, the boundaries of a panel–cavity system are usually imperfectly rigid. Therefore, this study examines the effect of cavity boundary on the resonant frequencies of the nonlinear system. It is the first work of employing the elliptic integral approach for solving this problem, which is involved with the nonlinear multi-mode governing equations of a large amplitude panel coupled with a cavity. The main advantage of this approach is that less nonlinear algebraic equations are generated in the solution steps. The present elliptic integral solution agrees reasonably well with the results obtained from a finite element harmonic balance method. The effects of other parameters such as vibration amplitude, cavity depth, aspect ratio, etc., are also investigated.
1 citations
TL;DR: It was found that the stop time and traffic flow are factors that also affect the sound level properties, and the first on-site measurement study about the effect of a traffic signal on the noise level of moving vehicles is conducted.
Abstract: Traffic noise is a major pollution problem in Hong Kong and many large cities throughout the world Indeed, traffic noise and traffic flow patterns interact, however, there is a very little research effort studying it To the best knowledge of the authors, the present research is the first on-site measurement study about the effect of a traffic signal on the noise level of moving vehicles Various cases of “stop and go” and “non-stop” were considered in the traffic noise measurements, where the terms “stop and go” and “non-stop” represent a traffic road with and without traffic signals, respectively The L10 and Leq noise levels were recorded and compared in the present study From the results, it was found that the stop time and traffic flow are factors that also affect the sound level properties
1 citations
TL;DR: In this article, the elliptic integral solution form is adopted to obtain the higher mode natural frequencies of the large amplitude rectangular plate backed by a cavity, which do not require heavy computation effort.
Abstract: In this article, the elliptic integral solution form is adopted to obtain the higher mode natural frequencies of the large amplitude rectangular plate backed by a cavity. The main advantage of the proposed method is the concise acoustic structural modal formulation which do not require heavy computation effort. A set of numerical results are presented for studying the higher mode natural frequencies.