新冠肺炎交通防控政策对长沙市人口流动的影响

为探究新冠肺炎疫情下交通防控政策对长沙市人口流动的影响，本文根据长沙市在新冠 肺炎疫情期间颁布的交通防控政策和疫情实时防控情况划分防控阶段，基于百度迁徙大数据，利 用双重差分模型，识别长沙市不同阶段的交通防控政策以及量化防控效果，分析交通防控政策对 长沙市人口流动的影响。结果显示，长沙市在交通管制阶段，平均人口迁出强度、平均人口迁入 强度及城市内部出行强度分别下降了83.68%、69.24%及59.74%，有效地控制了人口流动，降低了 疫情扩散危险。在交通恢复阶段，长沙市人口流动强度逐渐反弹，城市内部出行强度基本恢复到 2019年同期水平。本文研究结果显示了交通管制对疫情扩散限制的有效性，为常态化疫情防控 下精准防控政策和复工复产政策制定提供参考。     

通孔玻璃材料的研制

研究了利用废旧玻璃用松装烧结和模压烧结方法生产通孔材料的可能性，以及原始粉末尺寸、烧结工艺和造孔剂添加量对通孔材料的密度和孔隙度的影响。实验结果表明，用废旧玻璃经松装烧结或模压烧结后可制得通孔材料；松装烧结时，随烧结温度提高，烧结保温时间延长，原始粉末粒度变细，烧结后通孔材料的密度增大，而孔隙度降低；模压烧结时造孔剂的最佳百分含量为５％～５０％，且通孔材料随造孔剂的百分含量增加，密度降低，孔隙度增大。     

杭州城市交通拥挤现状及对策

在分析杭州市交通供需现状的基础上,提出了规划多中心结构和混合功能区,以减少不必要的出行以及合理配置交通源,并对改善中心区交通提出切实可行的对策。     

一种改进的基于密度和网格的高维聚类算法

提出了一种改进的基于密度和网格的高维聚类算法,并对算法有效性进行了验证.该算法通过减少样本点数量的方法达到减少稠密子空间数量.在发现高维稠密子空间时,对样本库进行精简.这些样本点的求得能有效减少求解最小聚类的时间复杂度.     

沥青混合料最大理论密度的计算

通过对矿质集料的物理状态及其在混合料中存在方式进行分析,探讨了沥青混合料最大理论密度计算中矿料密度的引用及其影响.     

沥青路面破损程度分级与破损换算系数取值的探讨

本文分析现行规范中对沥青路面破损程度、密度分级以及破损换算系数取值中存在问题,通过分析沥青路面破损程度与路面使用状况关系,结合沥青路面养护措施,提出沥青路面裂缝破损密度分级的方法,并对车辙破损严重程度分级标准、裂缝和车辙破损换算系数的修正值提出建议。     

The identification and empirical characterization of vehicular (Lagrangian) fundamental diagrams in multilane traffic flow

Traditional macroscopic traffic flow modeling framework adopts the spatial–temporal coordinate system to analyze traffic flow dynamics. With such modeling and analysis paradigm, complications arise for traffic flow data collected from mobile sensors such as probe vehicles equipped with mobile phones, Bluetooth, and Global Positioning System devices. The vehicle‐based measurement technologies call for new modeling thoughts that address the unique features of moving measurements and explore their full potential. In this paper, we look into the concept of vehicular fundamental diagram (VFD) and discuss its engineering implications. VFD corresponds to a conventional fundamental diagram (FD) in the kinematic wave (KW) theory that adopts space–time coordinates. Similar to the regular FD in the KW theory, VFD encapsulates all traffic flow dynamics. In this paper, to demonstrate the full potential of VFD in interpreting multilane traffic flow dynamics, we generalize the classical Edie's formula and propose a direct approach of reconstructing VFD from traffic measurements in the vehicular coordinates. A smoothing algorithm is proposed to effectively reduce the nonphysical fluctuation of traffic states calculated from multilane vehicle trajectories. As an example, we apply the proposed methodology to explore the next‐generation simulation datasets and identify the existence and forms of shock waves in different coordinate systems. Our findings provide empirical justifications and further insight for the Lagrangian traffic flow theory and models when applied in practice. Copyright © 2015 John Wiley & Sons, Ltd.     

A new model for temporal–spatial stochastic analysis of vehicle–track coupled systems

The vehicle–track coupled system has a random nature in the time–space domain. This paper proposes a computational model to analyse the temporal–spatial stochastic vibrations of vehicle–track systems, where the vehicle–track system is divided into a vehicle subsystem, track subsystem, and interfacial subsystem between the wheel and rail. In this model, the time-varying randomicity of dynamical parameters of the vehicle system, correlation, and randomness of the track structural parameters in the time–space joint dimensions, and randomness of the track random irregularities are considered. A probability dimension-reduction method was used to randomly combine different random variables. Furthermore, the probability density evolution method was applied to solve the delivery problem of probabilities between excitation inputs and response outputs. The temporal–spatial stochastic vibrations of the vehicle–track system with different coefficients of variation were studied, in which we assumed that the dynamic parameters obeyed the normal distribution, and the stochastic simulation method of the track random irregularities is probed into. The calculated results from this model are consistent with the actual measured results and physical conceptions. Thus, the temporal–spatial stochastic evolutionary mechanism can be explored, and the limits of dynamic indices can be formulated by using this developed model.     

内蒙古达斡尔族群体9个X-STR位点的遗传多态性及法医学应用价值评估

目的研究内蒙古达斡尔族群体9个X-STR位点(DXS6789、DXS101、DXS8378、DXS7132、DXS7133、DXS7423、DXS6804、DXS6799、HPRTB)的多态性分布及法医学应用价值。方法抽取内蒙古达斡尔族87名健康无关个体静脉血,提取DNA,经PCR扩增、变性聚丙烯酰胺凝胶电泳及银染显色技术进行等位基因分型;采用SPSS13.0软件计算各位点基因型频率和等位基因频率,并检验等位基因分布差异有无统计学意义;Genepop软件进行Hardy-Weinberg平衡检验;Fstat软件计算基因多态性、固定指数并检验固定指数偏离平衡的程度;Powerstats软件计算各种法医学应用指标。结果获得内蒙古达斡尔族群体9个X-STR位点等位基因频率分布的数据;进一步检验获得9个X-STR位点中DXS7133位点的多态性和分化程度较低;DXS7423和DXS7132位点在不同民族中基因分布差异无统计学意义。结论9个X-STR位点中,DXS6789、DXS101、DXS8378、DXS7132、DXS7423、DXS6804、DXS6799、HPRTB 8个位点有较高的遗传多态性和个体识别率,在个体识别和女孩的亲权鉴定中有较高应用价值,对疾病相关研究有实际意义。     

Effect of ABCA1-V771M polymorphism on plasma lipid levels and its relationship with coronary atherosclerotic heart disease

Objective To explore the risk association of ABCA1-V771M polymorphism with coronary heart disease (CHD) in Hart nationality in Northwest of China. Methods With case-control study, ABCA1-V771M polymorphism was detected in 204 unrelated Hart nationality people in Northwest of China, and all the subjects by coronary angiography were grouped into 106 cases and 98 controls. The genotypes and alleles frequency distribution of ABCA1-V771M polymorphisms were analyzed by PCR-RFLP analysis, and the clinical statistics of serum lipids were compared and its effects of ABCA1-V771M polymorphism on the plasma lipid levels and coronary atherosclerotic heart disease were analyzed. Results The genotypic frequencies of ABCA1-V771M polymorphism matched well under Hardy-Weinberg equilibrium (P>0.05), V and M allelic frequencies were 33.3% and 66.7%. In comparison with VV VM genotype carriers, MM genotypes carriers had much lower plasma levels of HDL-C (P<0. 001) and much higher plasma levels of TG (P<0. 05). M allelic frequency in CHD group was significantly higher than V allelic frequency (P<0. 05). M allele was related with more severity of atherosclerosis in the coronary artery than V allele (P<0.05). However, there was no obvious difference in the incidence of AMI among carriers with three genotypes of ABCA1-V771M polymorphism (P>0.05). Conclusion ABCA1-V771M polymorphism was not only associated with the plasma levels of HDL-C and TG, but also related to the susceptibility and severity of coronary atheroselerotic heart disease. Moreover, M771 allele appeared to be atherogenie among Han population in Northwest of China.