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为研究中国城市交通的混合交通特性,通过视频采集、视频处理、运动轨迹提取和坐标转化等一系列处理手段,提出了获取混合交通流中各类运动实体的轨迹线的基本方法.通过对轨迹数据的数据挖掘和回归分析,研究混合交通流中各类运动实体的空间位置和速度分布,分析了混合交通流中机动车和非机动车相互影响的成因和表现. 相似文献
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为研究宏观道路网络交通特性,以二流理论为基础,建立道路网络宏观交通特性的评价模型。该模型引入图论的分析方法,考虑可达性的评价指标和街道的实际交通情况,全面而抽象地描述城市道路网络路段与交叉口之间的关系,并给出道路网络宏观交通特性的评价指标,最后以一简单实例说明利用该模型评价城市道路网络宏观交通特性的过程。 相似文献
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Autonomous functions including mapping and path planning are very important to ensure efficient exploration and safe navigation
of unmanned rover. Conventional navigation schemes based on equipments such as GPS and magnetic sensors have been proven to
be ineffective on lunar surface, while sophisticated dead reckoning approach lacks accuracy in loose soil due to slippage.
In this paper, we propose a hybrid vision system (HVS) which consists of one stereo and one omnidirectional vision sensor,
attempting to integrate the advantages of diverse vision systems. The hierarchical mapping reconstructs environment through
HVS in different resolutions and structures, named qualitative, rough and detailed map. These maps are employed for path planning
which navigates the rover towards specified destinations autonomously, avoiding obstacles in its way. The HVS aims at providing
more efficient and safe navigation. Simulations and experiments demonstrate the functionality and advantage of our approach. 相似文献
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在华南地区循环湿热多雨气候的影响下,花岗岩残积土遇水极易崩解,诱发崩岗等地质灾害,对道路、桥梁等工程造成极大影响,因此常利用水泥、石灰和高岭土等固化剂对花岗岩残积土进行改良。为了进一步研究干湿循环条件下改良花岗岩残积土的崩解特性,采用自行设计的干湿循环崩解测试仪,开展华南地区干湿循环环境下改良花岗岩残积土的崩解试验,结合X射线衍射试验以及扫描电镜试验,研究固化剂对花岗岩残积土抗崩解性的改良效果,分析改良花岗岩残积土崩解机理。结果表明:干湿循环条件下,改良花岗岩残积土土样崩解过程可以分为4个阶段,即表层吸水剥落阶段、饱水软化阶段、饱和稳定阶段和完全解体阶段;干湿循环作用显著增大改良土崩解速率,部分试样崩解速率可达到原来的2~3倍,添加固化剂能有效增强花岗岩残积土的抗崩解性,完全崩解时长增加到素土的2~6倍;基于绿化角度,掺入高岭土对花岗岩残积土进行改良较为合适;素土以及改良土崩解过程中,土样黏土矿物(例如高岭石)含量减少,显著降低土样胶结作用,促进土样崩解的发生;花岗岩残积土内部孔隙大小分布不均匀的结构特征,使土样在崩解过程中产生吸力不平衡现象,较小的孔隙先被水填入,压缩土样孔隙内的空气... 相似文献
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在分析目前城市快速路实际使用的入口控制模型的基础上,引入时空资源效用参数作为控制变量,将并行多路任务负载均衡模型与传统ALINEA策略相结合,提出了以主辅路资源效用均衡化为主导思想的城市快速路入口均衡控制模型(TBM). 为提高模型的实用性,本文提出“非对称性改进”和“局部出入口弱互扰情况下的资源折减”这两项改进措施,并将改进的NEMA排队感应模型作为回溢的控制手段. 以合肥金寨路高架桥为背景,进行实地测试,结果表明主路平均行程时间减少了9.09%~9.44%,局部拥挤现象明显减少. 最后讨论了控制模型在不同交通条件下的适用性,均衡控制模型在高峰时段,特别是在主辅路局部拥挤程度不同的条件下,局部拥挤的改善效果比较显著. 相似文献
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Near infrared (NIR) hyperspectral imaging measurement of sugar content in peach was introduced. NIR spectral images (650~1 000 nm, resolution: 2 nm) of peach samples were captured with developed hyperspectral imaging setup. Partial least square (PLS) regression prediction model was developed to estimate the sugar content in peach; step-wise backward method was utilized to determine optimal wavelength subsets. Experimental results show that the calibration model with optimal wavelength subsets has a correlation coefficient of prediction of 0.97 and a standard error of prediction of 0.19, the prediction accuracy is higher than the calibration model applied over the whole wavelength, which proves that variable selection plays an important role in improving the prediction accuracy of PLS regression model. 相似文献
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An optical inspection method of the Ball Grid Array package (BGA) was proposed by using a machine vision system. The developed machine vision system could get main critical factors for BGA quality evaluation, such as the height of solder ball, diameter, pitch and coplanarity. The experiment has proved that this system is available for BGA failure detection. 相似文献