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681.
为分析悬架控制对汽车道路友好性的影响,基于简化的二自由度1/4车辆模型,设计了主动悬架LQG最优控制器,并在MATALB/Simulink环境下建立了主动悬架道路友好性仿真模型.基于改善汽车道路友好性的需要,采用层次分析法确定各性能指标权重,并利用Simulink/SRO模块对悬架控制参数进行优化.仿真结果表明,相对于被动悬架,主动悬架能有效降低汽车轮胎动载荷,从而提高道路友好性,且优化后的主动悬架道路友好性能更优. 相似文献
682.
Active tamper detection using watermarking technique can localize the tampered area and recover the lost information. In this paper, we propose an approach that the watermark is robust to legitimate lossy compression, fragile to malicious tampering and capable of recovery. We embed the watermark bits in the direct current value of energy concentration transform domain coefficients. Let the original watermark bits be content dependent and apply error correction coding to them before embedded to the image. While indicating the tampered area, the extracted bits from a suspicious image can be further decoded and then used to roughly recover the corresponding area. We also theoretically study the image quality and bit error rate. Experimental results demonstrate the effectiveness of the proposed scheme. 相似文献
683.
设计了8种不同控制思路下的决策方案,并在每种决策方案下,综合考虑社会车流绿波带和公交车流绿波带,分析上游交叉口到达下游交叉口的时刻对绿波带的影响情况,建立了基于绿波带宽度的优化目标。以社会车流和公交车流能够获得的绿波带宽度之和最优为原则,确定出8种决策中的最佳决策,并对控制算法进行了验证。提出的信号配时优化方法不仅可以同时满足社会车流和公交车流需求,还可以实现绿波带最大化。 相似文献
684.
基于主动控制思想,应用数理统计方法,分析广州大学城交通信号灯灯色转换时刻的变化情况,研究信号灯灯色转换时刻变化的规律,建立灯色转换时刻与时问之间的逻辑关系模型,并建立查询信号灯周期状态的预测模型。通过主动控制的手段,使得驾驶员掌握行驶路段中信号灯的状态,提高交通行车效率。 相似文献
685.
686.
为了研究高水位地区地下结构抗浮问题,提出在地下结构基础底板下方设置具有专利技术的S型排水DM(drainage mat)地下结构主动抗浮措施,采用数值分析深入研究地下结构主动抗浮工作机制,制定了地下结构主动抗浮措施的设计原则和计算方法,并应用于厦门和昌中心地下结构抗浮工程中。研究表明,地下结构主动抗浮措施消减了基础底板下方土体孔隙水压力,达到地下结构抗浮目标,节省了工期和造价,工程应用前景广阔。 相似文献
687.
Freeway merging sections are critical segments that can recurrently activate peak-hour traffic congestion. This article proposes a novel vehicular gap control method as a new Active Traffic Management (ATM) strategy to be added to the existing Intelligent Transportation System (ITS) toolboxes for freeway merge control. The proposed strategy, “Gap Metering,” can be considered a non-stopping mainline version of ramp metering. It utilizes signals advising mainline through vehicles to yield sufficient gaps for merging vehicles. Detailed system design and control methods are proposed and implemented in VISSIM (please spell out the abbreviation of VISSIM for this first instance), a microsimulation software package. Different driver behavior sets with different standstill headway values are created to allow switching between gap-metered vehicles and regular vehicles. We evaluate the proposed system through two VISSIM models built and calibrated, respectively, for both the I-894 corridor in Milwaukee, WI, and the Riverside Drive segment on I-35 northbound in Austin, TX. Both corridors experience severe morning peak-hour congestion. We use the I-894 corridor for testing the system design parameters and use the I-35 corridor to conduct a comparison with the ramp metering strategies. The I-894 results indicate an average of 10–20% network delay reduction among all scenarios. We then tested the scenario on the I-35 corridor and compared with the ALINEAR ramp metering. Gap metering strategies alone or combined with ramp metering can, respectively, reduce 17% and 27% more total delay than ramp metering only control at 20% compliance rate. 相似文献
688.
689.
Zhilin Jin Lei Zhang Jiale Zhang Amir Khajepour 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2016,54(10):1405-1427
Vehicle rollover is a serious traffic accident. In order to accurately evaluate the possibility of untripped and some special tripped vehicle rollovers, and to prevent vehicle rollover under unpredictable variations of parameters and harsh driving conditions, a new rollover index and an anti-roll control strategy are proposed in this paper. Taking deflections of steering and suspension induced by the roll at the axles into consideration, a six degrees of freedom dynamic model is established, including lateral, yaw, roll, and vertical motions of sprung and unsprung masses. From the vehicle dynamics theory, a new rollover index is developed to predict vehicle rollover risk under both untripped and special tripped situations. This new rollover index is validated by Carsim simulations. In addition, an H-infinity controller with electro hydraulic brake system is optimised by genetic algorithm to improve the anti-rollover performance of the vehicle. The stability and robustness of the active rollover prevention control system are analysed by some numerical simulations. The results show that the control system can improve the critical speed of vehicle rollover obviously, and has a good robustness for variations in the number of passengers and longitude position of the centre of gravity. 相似文献
690.