The relationship between fracture toughness VGC and critical void growth RC/RO was studied for ten kinds of Steel. The macroscopic fracture toughness VGC was determined by using notched tensile specimens. and the micr...The relationship between fracture toughness VGC and critical void growth RC/RO was studied for ten kinds of Steel. The macroscopic fracture toughness VGC was determined by using notched tensile specimens. and the microscopic parameters of critical void growth ratio RC/RO were quantitatively measured under SEM. Then, the coefhcient C in the relation VGC = C In(RC/RO) proposed in author's past work was specifically explored. The correlation of C with tensile proderty parameter φ=σyδ/(Eφn) was presented for the Steel investigated, and the effects of low temperature on C were also discussed. Results show that the coefficient C is linearly related to the parameter and insensitive to low temperature.展开更多
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
为了解决我国城市道路信号配时过程中遇到的车流离散性较大、难以用简单模型来描述车流运动规律的问题,借助波动系数理论,以15 m in交通量统计数据为基础,分析了信号交叉口交通量的波动特性,指出信号交叉口交通量在纵向上具有一致性,在...为了解决我国城市道路信号配时过程中遇到的车流离散性较大、难以用简单模型来描述车流运动规律的问题,借助波动系数理论,以15 m in交通量统计数据为基础,分析了信号交叉口交通量的波动特性,指出信号交叉口交通量在纵向上具有一致性,在横向上具有差异性,而且随着V/C比的增大,车流到达的波动性逐渐降低.基于信号交叉口交通量的波动特性,结合自适应控制与感应控制的思想,形成了一种新的信号控制参数优化算法,实践应用证明,该算法针对交叉口车流到达的随机性具有较强的适应性.展开更多
文摘The relationship between fracture toughness VGC and critical void growth RC/RO was studied for ten kinds of Steel. The macroscopic fracture toughness VGC was determined by using notched tensile specimens. and the microscopic parameters of critical void growth ratio RC/RO were quantitatively measured under SEM. Then, the coefhcient C in the relation VGC = C In(RC/RO) proposed in author's past work was specifically explored. The correlation of C with tensile proderty parameter φ=σyδ/(Eφn) was presented for the Steel investigated, and the effects of low temperature on C were also discussed. Results show that the coefficient C is linearly related to the parameter and insensitive to low temperature.
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。
文摘为了解决我国城市道路信号配时过程中遇到的车流离散性较大、难以用简单模型来描述车流运动规律的问题,借助波动系数理论,以15 m in交通量统计数据为基础,分析了信号交叉口交通量的波动特性,指出信号交叉口交通量在纵向上具有一致性,在横向上具有差异性,而且随着V/C比的增大,车流到达的波动性逐渐降低.基于信号交叉口交通量的波动特性,结合自适应控制与感应控制的思想,形成了一种新的信号控制参数优化算法,实践应用证明,该算法针对交叉口车流到达的随机性具有较强的适应性.
