城市群轨道交通方式划分非集计logit模型

以城市群轨道交通方式划分为研究对象,根据城市群轨道交通特点,提出将城市群客流分为城区客流和城际客流,分别预测其轨道交通分担率.利用非集计模型的基础理论,选取时间、费用与个人收入的比值作为效用函数的特性变量,以交通行为调查的RP和SP联合数据为基础,建立了应用于城市群交通方式划分的非集计模型.并以长株潭城际轨道交通方式划分为例,进行了参数估计和轨道交通分担率的预测.     

Reducing average comprehensive travel cost by rationally allocating trips to different travel modes

To study the effect of different transport policies on reducing the average comprehensive travel cost (CTC) of all travel modes, by increasing public transport modal share and decreasing car trips, an optimization model is developed based on travel cost utility. A nested logit model is applied to analyze trip modal split. A Genetic Algorithm is then used to determine the implementation of optimal solutions in which various transport policies are applied in order to reduce average CTC. The central urban region of Beijing is selected as the study area in this research. Different policies are analyzed for comparison, focusing on their optimal impacts on minimizing the average CTC utility of all travel modes by rationally allocating trips to different travel modes in the study area. It is found that the proposed optimization model provides a reasonable indication of the effect of policies applied.     

浅析输送带撕裂原因及应对措施

叙述了皮带输送机输送带撕裂的形式及原因,又介绍了国内外如何防止输送带撕裂及对输送带撕裂进行检测的措施,最后从技术角度提了几点建议,强调要进行新技术的开发与应用。     

沥青路面中结构参数的均值对路面可靠指标的影响

对沥青路面各项结构参数均值的变化给路面各项可靠指标造成的影响进行了较深刻的探讨     

单翼分解下的纯度函数失效分析

为了清晰地说明纯度函数失效的原因,首先拓展了纯度函数的定义,得到一种能方便运用数学方法表示的新纯度函数形式,并在其基础上,分析了有些纯度函数在有些情况下会失效,而另外的一些却不会．说明了这种“预测性能”实际上与纯度函数某种特殊的“凹凸性”有关,这种凹凸性只在特定的方向才呈现出来．通过若干定理,阐明了如何通过赫斯矩阵寻找这些特定的方向,而纯度函数的“预测性能”本质上就是该方向性严格凸性质．最后通过若干实验数据,验证了结论．     

Analysis of planetary gear hybrid powertrain system part 2: Output split system

In recent studies, various types of multi-mode electric variable transmissions for hybrid electric vehicles have been proposed. A multi-mode electric variable transmission consists of two or more different types of a planetary gear hybrid powertrain system (PGHP), which can change power flow type using clutches to improve transmission efficiency. Input split systems are generally used for the single-mode powertrain because of their overall superiority, but other power split systems such as output split and compound split systems can be used in the dual-mode powertrain. In this study, we analyze the power transmission characteristics of output split systems, and evaluate their fuel economies in the FTP72 cycle, acceleration performance, and constant vehicle speeds. These results enable the selection of appropriate systems for a dual-mode powertrain.     

Expansion of a Controlled Parking Zone (CPZ) and its Influence on Modal Split: The Case of Edinburgh

Abstract

This article considers the inter-relationship between on-street parking and choice of mode for journeys to work in the Scottish city of Edinburgh. This city is typical of many in that its centre has significant on-street parking controls but, beyond a radius of 1 to 1 1/2 miles (1.5 to 2.5?km) from the centre, there are no controls and commuter parking on-street is commonplace. The article reviews the relevant literature, and then considers the results of a survey undertaken of Edinburgh city centre employees in order to ascertain their parking habits and likely response to the extension of existing on-street parking controls. The article concludes that the results are transferable to other cities but that the scale of the impacts in each will be related to site specific factors, particularly the demand for residential parking space on-street in areas close to the city centre.     

基于巢式Logit模型的航空港集疏运方式选择研究

为研究航空旅客出行方式选择行为,在航空港集疏运系统需求描述的基础上,介绍并运用巢式Logit模型原理,以广州白云国际机场为实例,建立适用于白云机场集疏运系统的方式选择模型(NL模型),分析确定各相关影响因素项的影响机理,运用最大似然估计法对虚拟选择枝的共性和相异部分的参数进行修正和标定,从而获取各种集疏运方式的选择概率.结合调查选取的20份样本数据,运用模型编程计算得出私人小汽车、出租车、机场巴士、城际巴士和城市轨道共5种集疏运方式的方式选择概率分布结果,结果显示私人小汽车和出租车二者占比大于45%,机场巴士和城际巴士占比约40%,城市轨道仅占比15%.因此,为大力发展城市的公共交通,需要对白云机场提出具有参考性集疏运系统改进方案,为今后航空港集疏运系统的发展和航空旅客交通方式选择行为研究提供一定的借鉴.     

纳米碳纤维混凝土力学性能的试验研究

纳米碳纤维作为一种新型材料,具有高强度,高弹性模量等力学上的优异特性.通过单轴抗压试验和劈裂试验,测试了掺加3种类型纳米碳纤维的普通混凝土和自密实混凝土的基本力学性能,并讨论其最优掺量.实验结果表明:适当掺量且纤维分散良好的纳米碳纤维混凝土28 d抗压强度和劈裂强度均有不同程度的提高,表明纳米碳纤维对于混凝土材料力学性...     

混合动力汽车功率分配装置的功率传动分析

针对混合动力汽车功率分配装置这一关键部件,分析了以行星齿轮机构为核心的功率分配装置的动力学特性,得出了动力学方程,详细讨论了在各种驱动模式下的功率分配传动过程和效率,其结果可作为下一步混合电动汽车整车能量优化控制研究的基础.