In Changchun, China, roundabouts are fairly common. They are often designed to connect the main roads because of their ability to reduce conflict points, making them safer than other intersections. They can also beaut...In Changchun, China, roundabouts are fairly common. They are often designed to connect the main roads because of their ability to reduce conflict points, making them safer than other intersections. They can also beautify the city when the central islands are landscaped. However, with increasing traffic, they may not function well and may even paralyze the road network. This means that it is important to evaluate the performance of roundabouts promptly, and to make necessary improvements if required. Using several roundabouts in Changchun as case studies, this article uses V/C ratio and delay to evaluate roundabout performance. Based on the result of evaluation, the micro-simulation model of the poorly-performing roundabout is built and enhancement is proposed.展开更多
文摘In Changchun, China, roundabouts are fairly common. They are often designed to connect the main roads because of their ability to reduce conflict points, making them safer than other intersections. They can also beautify the city when the central islands are landscaped. However, with increasing traffic, they may not function well and may even paralyze the road network. This means that it is important to evaluate the performance of roundabouts promptly, and to make necessary improvements if required. Using several roundabouts in Changchun as case studies, this article uses V/C ratio and delay to evaluate roundabout performance. Based on the result of evaluation, the micro-simulation model of the poorly-performing roundabout is built and enhancement is proposed.
文摘为了进一步提高电学层析成像(ECT)采集系统的测量精度,分析研究了ECT信号的完整性对测量结果的影响。针对测量电容信号微弱、值在p F级别的特点,设计出一种考虑信号完整性的ECT采集系统,其传感器占空比为81%。利用上述系统来分析信号完整性对测量结果的影响。实验结果表明:当正弦激励信号的峰峰值为18.7 V时,采集到的最大信号经过电流/电压(C/V)转换后的电压峰峰值为921 m V,与理论计算结果基本吻合;运用灵敏度矩阵系数算法,在PC上得出了清晰的ECT图像。表明该测量系统满足精度要求。
