半刚性基层材料动态特性研究

在交通荷载的作用下,路面材料的性质都与现行的静态力学体系有着较大的差距。本文对影响动态模量的各种试验因素进行了分析、整理,初步确定了室内动态参数试验的试验力学参数、试样制备要求、数据采集和分析等试验方法和分析程序。针对目前国内最常见的路面基层材料———水泥稳定碎石,进行了不同级配、不同剂量条件下大量的室内试验,在此基础上建立了半刚性路面材料动态参数与抗压强度、荷载水平的关系式,探索了动静态参数之间的关系。     

城市交通生成预测实用分析模型及其应用

以城市土地利用特性为基本变量,采用回归分析和系统聚类分析方法建立了交通生成预测实用分析模型。模型应用于浙江湖州市城市综合交通规划实践,结果表明模型能够反映规划年城市土地利用特征变化所带来的各组团交通需求特性的差异,并且具有简捷、实用、可操作性强的特点。     

呼和浩特市客运出租汽车数量预测模型研究

一个城市的客运出租市场是否需要投放出租汽车和投放数量的多少,不仅影响服务质量,也影响每位出租汽车经营者的自身利益,从而影响整个．出租汽车行业的稳定与健康发展。本文对出租汽车影响较大的因素进行了统计和相关性分析,确定了自变量,采用回归模型和曲线拟合的方法建立了未来年份的出租汽车数量预测模型,预测结果和往年历史数据对比表明,时间变量的一元线性模型和实际值较接近;幂函数曲线的预测值增加较快,就呼和浩特市的具体情况,幂函数曲线的预测效果较好。本文给出了适合呼和浩特市区的出租汽车发展趋势和合理的数量预测。     

Paying for harbor maintenance in the US: Options for moving past the Harbor Maintenance Tax

The Harbor Maintenance Tax is a fundamentally flawed maintenance funding mechanism for the critical US port system. Three alternatives were analyzed. User fee rates were estimated for either a national or regional tonnage based fee. Our results indicate that maintenance cost recovering regional fees could vary widely from about 10 cents per tonne to nearly 80 cents per tonne. A national rate would be about 30 cents per tonne. The large regional differences and affects on bulk shippers are likely to make implementing and maintaining cost recovering tonnage based fees infeasible. Two other mechanisms are considered. One possibility is to abolish the HMT without a replacement mechanism. The obvious strength of this approach is its simplicity, the weaknesses is that it is not budget neutral. Another possibility is to increase the federal diesel tax rate. One strength of the approach is the reasonable rate increase required to recover port maintenance costs (estimated between 0.278 and 0.315 cents per liter). An additional strength is that relatively inefficient fuel users will either make the largest share of the additional payments or the freight will shift modes to one that is more efficient. One weakness is that the rate has been unchanged since 1997, this points to the political difficulty involved in passing such a rate increase.     

北京驾驶员培训行业需求预测和发展研究

机动车驾驶员的素质能够对城市交通运行产生重大影响,良好的技术水平和高尚道德素质的驾驶员,对于保证城市交通安全运行和人民生命财产的安全至关重要。通过开展驾驶员培训市场需求总量的预测研究,能够有效引导培训市场的合理竞争,提升驾驶员培训行业的高质量发展。本文系统分析了驾驶员培训市场需求预测的方法,以北京驾培市场为实例,基于城市新总规,综合考虑经济社会发展、城市人口变化、城市机动车调控和驾驶证饱和率等多种因素,预测未来培训市场需求情况。根据预测结果和市场培训能力对比,提出了针对行业总量发展的对策建议,也能为国内城市进行驾培需求预测研究和行业发展提供参考。     

Is awareness of public charging associated with consumer interest in plug-in electric vehicles?

Policymakers often seek to increase the visibility of plug-in electric vehicle (PEV) chargers in public locations in effort to build familiarity and interest in PEVs. However, it is not clear if the visibility of public charging stations actually has an impact on PEV demand. The purposes of the present study are to (1) assess the current levels of visibility for public PEV charging infrastructure within Canada and (2) identify whether or not a statistically significant relationship exists between consumer awareness of public charging infrastructure and interest in purchasing a PEV. We use data collected from a sample of 1739 Canadian new-vehicle buyers in 2013. About 18% of Canadian respondents have seen at least one public charger, while the proportion is highest in British Columbia (31%). We find a significant bivariate relationship between public charger awareness and PEV interest. However, when controlling for multiple explanatory variables in regression analyses, the relationship is weak or non-existent. While perceived existence of at least one charger exhibits no significant relationship with PEV interest, perceived existence of multiple chargers can have a weak but significant relationship. Thus, public charger awareness is not a strong predictor of PEV interest; other variables are more important, such as the availability of level 1 (110/120-volt) charging at home.     

潜航器轨迹跟踪与航向预测算法

海况条件较差时,基于水下单点GPS定位系统的潜航器实时定位有较大测量误差,不利于潜航器的轨迹跟踪与航向预测。针对误差服从高斯分布的水下单点GPS定位系统,提出基于改进型扩展卡尔曼滤波算法的GPS跟踪方法和基于回归分析算法的航向预测方法。通过测试与仿真,对定位设备采集到的数据进行对比分析,试验结果表明,上述算法显著提高了轨迹测量精度与航向跟踪能力,准确绘制出了潜航器的实时航行轨迹与航向预测线,可应用于潜航器的轨迹跟踪项目中。     

Characterization and prediction of air traffic delays

This paper presents a new class of models for predicting air traffic delays. The proposed models consider both temporal and spatial (that is, network) delay states as explanatory variables, and use Random Forest algorithms to predict departure delays 2–24 h in the future. In addition to local delay variables that describe the arrival or departure delay states of the most influential airports and links (origin–destination pairs) in the network, new network delay variables that characterize the global delay state of the entire National Airspace System at the time of prediction are proposed. The paper analyzes the performance of the proposed prediction models in both classifying delays as above or below a certain threshold, as well as predicting delay values. The models are trained and validated on operational data from 2007 and 2008, and are evaluated using the 100 most-delayed links in the system. The results show that for a 2-h forecast horizon, the average test error over these 100 links is 19% when classifying delays as above or below 60 min. Similarly, the average over these 100 links of the median test error is found to be 21 min when predicting departure delays for a 2-h forecast horizon. The effects of changes in the classification threshold and forecast horizon on prediction performance are studied.     

LNG运输船船型浅析

简述了LNG船的沿革、液货舱的类型及典型结构、总布置特征、船舶要素特征以及具体防火要求，并根据大量的实船资料，通过回归统计分析的方法得出船舶主尺度与总吨位间的系列关系曲线。     

公路路基黄土湿陷性的室内实验研究

本文总结了目前关于湿陷性黄土湿陷机理的诸观点,对典型的湿陷性黄土地区的公路路基黄土进行了大量野外取样并进行了室内湿陷性试验,通过对试验结果的回归分析揭示了湿陷性与含水量、孔隙比、塑性指数的定量关系;并通过对切取的sem电镜照片进行分析,从微观角度对黄土微观结构特征与湿陷性之间的关系进行了有益的探讨。