对土工标准击实试验中几个问题的探讨

压实度检测是路基强度检测的常用方法之一,室内标准击实试验结果的准确性至关重要,其影响因素也较多。用大量数据阐述了含水率、土的类别、塑性指数、湿法与干法、土样的重复使用、余土高度等影响因素。还对试验数据的处理和实际工程中经常出现的压实度大于1的现象以及碾压含水率范围都做了较深入的研究,以期与同行探讨。通过对上述因素和问题的分析,提出合理化的试验方法,更有利于指导现场施工。     

道路不平程度的评价方法及相互关系研究

通过回归分析的方法对标准分级道路功率谱密度与相应国际平整度指数之间的关系进行了研究.根据标准道路谱再现出随机路面,以此作为输入去激励标准1/4车辆模型,从而获得与标准道路谱相应的国际平整度指数,然后利用回归分析获得了标准道路谱与国际平整度指数之间的关系.     

CNG/LPG的能量密度及用于摩托车的可行性研究

如今多种代用燃料正逐渐被应用到内燃机上,在诸多代用燃料中,天然气和液化石油气以来源广泛、可靠、经济性好、技术可行、燃烧排放低而被作为"清洁燃料"受到世界各国的重视和推广.本文提出能量密度和能量密度系数的概念,将LPG、CNG和汽油加以比较,以探讨LPG、CNG作为摩托车代用燃料的可行性.     

密度测定方法对橡胶颗粒沥青混合料空隙率的影响

空隙率是影响路面使用性能的一个重要指标,它的变化直接影响道路使用性能,而空隙率又受密度测定方法影响。文章采用不同密度测定方法,对废旧橡胶颗粒沥青混合料密度进行检测,并分别计算其空隙率。通过与普通沥青混合料作对比,得出掺入橡胶颗粒后沥青混合料空隙率的变化规律,并对不同密度测定方法下得出的空隙率进行比较分析,得出密度测定方法对空隙率影响的变化规律。     

沥青混合料空隙率影响因素研究

通过对不同级配细粒式沥青混合料的研究，分析了集料密度和混合料空隙率的不同测试方法和计算方法对于确定沥青混合料空隙率的影响，对其间的异同及相互关系进行了探讨，提出了确定沥青混合料空隙率时应尽量避免的人为影响，同时对今后测定和计算方法的规范化进行了展望。     

高速铁路接触线不平顺线谱研究

功率谱密度函数可以从波长和幅值两方面反应接触线不平顺的特征和规律,是研究接触线不平顺状态的重要工具。本文以我国多条高速铁路线路的接触线垂向不平顺实测数据为基础,采用最大熵谱估计得到接触线不平顺实测功率谱,并提出一种普适性强、结构简单的不平顺线谱模型。研究结果表明:我国高速铁路线路的PSD最值均小于0.01m2/m-1,接触线整体不平顺状态较好;随机不平顺中含有的周期性简谐波成分,波长主要为单倍跨距和单倍吊弦距;文中建立的接触线不平顺线谱新模型参数少、普适性强、拟合效果优,并给出该模型参数的非线性最小二乘估算结果。     

广州地铁运营客流分布特征研究与应用

针对目前广州地铁运营过程中列车车厢及车站站台过度拥挤的问题,通过对广州地铁实际运营客流分布特征的调查与分析,在时间维度上提出客流分布在年内、月内及周内的不均衡规律,分析节假日对车站客流的影响,在空间维度上分析车厢内客流密度在不同区间、不同编组、不同车厢区域的分布规律和客流在车站站台上的分布规律。通过对现状特征的重新审视,提出设计阶段客流预测数据的选用原则、车厢站立密度对站台乘客上下车时间的影响及车站布局形式与站台客流分布的关系。为广州后续轨道交通线路精细化设计提供依据,为国内类似城市地铁设计、运营组织提供参考。     

低密度聚乙烯（LDPE）对沥青粘弹性能影响

对低密度聚乙烯（LDPE）作为沥青改性剂的性能进行了试验研究,采用了动态流变试验和布氏粘度试验对改性沥青的流变性及粘弹剪切性能进行了分析,并分析了不同的LDPE掺量对两种沥青性能的影响。试验结果表明随着LDPE的掺量的增多复数模量呈现降低趋势、相位角为增长趋势,同时抗车辙因子增大,表明LDPE的加入提高了沥青的弹性性能和高温抗变形能力;同时随着LDPE用量的增加,沥青的粘度也逐渐增加,沥青的剪切指数逐渐减小,沥青的非牛顿体特征更加明显。     

Does urbanization lead to less energy use on road transport? Evidence from municipalities in Norway

The relationship between urbanization, energy use, and CO₂ emissions has been extensively studied in recent years, however little attention paid to the differences in urban forms. Previous studies implicitly assume that the urban form is homogenous across different urban areas. Such an assumption is questionable as urban form can have many different facets. This paper investigates the effects of urbanization on the road transport energy use by considering different urban forms from a dataset of 386 Norwegian municipalities from 2006 to 2009. Using the Stochastic Impacts by Regression on Population, Affluence, and Technology (STIRPAT) model with an energy use identity equation, the main findings (1) confirm the well-established result that urban density has a negative and significant influence on road transport energy use, and (2) demonstrate that the effect of urbanization partly depends on the level of urban density. These results imply that additional increases in urbanization in dense areas yield greater decreases in road transport energy use per capita. Additional findings posit that (3) there is a non-linear (quadratic) relationship between road energy use per capita and urban population. This implies that an increase in total municipality population over a specific turning point can result in a decrease in road energy use per capita. However, (4) the ratio of urban residential buildings with private gardens has a negative and significant influence on road transport energy use. This implies that there may be a trade-off between compact and sprawl city development strategies, highlighting that sustainable energy use requires further investigation.     

Robust transit network design with stochastic demand considering development density

This paper analyzes the influence of urban development density on transit network design with stochastic demand by considering two types of services, rapid transit services, such as rail, and flexible services, such as dial-a-ride shuttles. Rapid transit services operate on fixed routes and dedicated lanes, and with fixed schedules, whereas dial-a-ride services can make use of the existing road network, hence are much more economical to implement. It is obvious that the urban development densities to financially sustain these two service types are different. This study integrates these two service networks into one multi-modal network and then determines the optimal combination of these two service types under user equilibrium (UE) flows for a given urban density. Then we investigate the minimum or critical urban density required to financially sustain the rapid transit line(s). The approach of robust optimization is used to address the stochastic demands as captured in a polyhedral uncertainty set, which is then reformulated by its dual problem and incorporated accordingly. The UE principle is represented by a set of variational inequality (VI) constraints. Eventually, the whole problem is linearized and formulated as a mixed-integer linear program. A cutting constraint algorithm is adopted to address the computational difficulty arising from the VI constraints. The paper studies the implications of three different population distribution patterns, two CBD locations, and produces the resultant sequences of adding more rapid transit services as the population density increases.