新冠疫情对居民休闲出行影响研究

为了就新冠疫情对疫情结束后居民休闲出行的影响展开调查研究,把握疫情后居民休闲出行偏好的变化,分析休闲出行意愿的影响因素和影响机制,并量化分析各因素的影响,基于计划行为理论和收益-风险分析构建结构方程模型,量化感知风险、感知正效用、出行态度、主观规范、感知行为控制等影响因素与疫情后休闲出行意愿的相互影响机制,并利用单因素...     

考虑心理潜变量的城市电动自行车用户出行决策行为

为探究电动自行车用户对不同城市电动自行车规范管理政策的行为响应机理,采用问卷调查方法收集用户的社会人口特征、出行特征、心理特征以及在不同政策下的决策,基于心理接受度等潜变量构建了多指标多因素模型, 得出了潜变量的拟合值,将潜变量作为解释变量引入到行为决策模型中,构成了混合选择模型来分析社会人口变量、出行特征变量和心理潜变量对电动自行车用户出行决策的影响。结果表明:①电动自行车用户的心理特征显著影响其出行决策行为,对政策接受度更高的用户会表现出更强的正面行为倾向;②经济因素是导致出行者继续使用超标违规电动自行车或违反政策的主要原因;③提供报废补贴能中和收入对决策的影响,促进低收入家庭购买符合标准的电动自行车;④政策的实施会促进电动自行车交通向小汽车交通的转移。      

Commuting travel behavior focusing on the role of shared transportation in the wake of the COVID-19 pandemic and the Tokyo Olympics

To maintain life in the face of the COVID-19, people's lifestyles and travel behaviors must change. Accordingly, such changes have also occurred in the travel behavior for commuting purposes, especially during periods of severe congestion. The most typical example is the decrease in commuting travel due to telecommunication and other factors. Additionally, with the development of the sharing economy in recent years, the introduction of shared transportation has been rapidly expanding in the transportation sector, which may contribute to alleviating traffic congestion and other problems in the COVID-19 situation. In this study, we focused on the changes in travel behavior for commuting purposes during the COVID-19 period, including the time of the Tokyo Olympics, when traffic congestion was expected. The survey was conducted using a web-based questionnaire. In addition, to further promote changes in the travel behavior during the COVID-19 period, we analyzed the possibility of changes in the use of shared transportation arising from nudge effects of information provision and incentives. The results showed that the changes in commuting travel behavior were related to the awareness of COVID-19. Certain issues, such as a lack of ports and the widespread use of shared transportation need to be identified and resolved. Meanwhile, it was shown that the role of shared transportation for commuting purposes could be further improved by incentives and real-time information presentation about shared transportation.     

基于扩展TAM的车路协同系统驾驶人接受度研究

车路协同系统（Cooperative Vehicle Infrastructure System，CVIS）已成为智能交通领域的前沿技术和研究热点。世界各国都在致力于CVIS的研发、试验、示范应用和效用评估。然而CVIS的服务对象是驾驶人，在其正式投入使用之前研究驾驶人对CVIS的主观接受度及其影响因素非常重要。基于此，以基础的技术接受模型（Technology Acceptance Model，TAM）为理论框架，在基础变量（感知有用性、感知易用性、态度和使用意图）的基础上，引入预警服务质量、分心感知、个人创新和信任度4个扩展变量，建立扩展TAM，分析驾驶人对CVIS的主观接受度及其影响因素。首先，通过在线调查收集392名驾驶人对CVIS的技术接受问卷；然后，使用Cronbach's α和验证性因子分析检验问卷的信效度；最后，采用路径分析探究驾驶人对CVIS的接受度及其影响因素。研究结果表明：基础TAM变量之间的关系与基础模型假设一致；CVIS的预警服务质量通过感知有用性、感知易用性和态度间接影响使用意图；驾驶人对CVIS的分心感知对其态度和使用意图没有负向影响；驾驶人的个人创新不仅直接影响使用意图，而且通过态度间接影响使用意图；驾驶人对CVIS的信任度是使用意图的直接影响因素，也通过其他变量间接影响使用意图。研究结果有助于了解驾驶人对CVIS的接受度及其影响因素，并为CVIS的设计提供理论依据。     

On the wobble mode of a bicycle

Wheel shimmy and wobble are well-known dynamic phenomena at automobiles, aeroplanes and motorcycles. In particular, wobble at the motorcycle is an (unstable) eigenmode with oscillations of the wheel about the steering axis, and it is no surprise that unstable bicycle wobble is perceived unpleasant or may be dangerous, if not controlled by the rider in time. Basic research on wobble at motorcycles within the last decades has revealed a better understanding of the sudden onset of wobble, and the complex relations between parameters affecting wobble have been identified. These fundamental findings have been transferred to bicycles. As mass distribution and inertial properties, rider influence and lateral compliances of tyre and frame differ at bicycle and motorcycle, models to represent wobble at motorcycles have to prove themselves, when applied to bicycles. For that purpose numerical results are compared with measurements from test runs, and parametric influences on the stability of the wobble mode at bicycles have been evolved. All numerical analysis and measurements are based on a specific test bicycle equipped with steering angle sensor, wheel-speed sensor, global positioning system (GPS) 3-axis accelerometer, and 3-axis angular velocity gyroscopic sensor.     

Les systèmes de vélos en libre-service expliquent-ils le retour du vélo en ville ?

Many French and European cities have developed a bike sharing system since 2005. This policy may be explained in a great part by the success of the Velo??v in Lyon, which contributed to improve the image of cycling in the city. If bicycles, however, appear to find a new place in the city, one can wonder whether this is really due to bike sharing systems? What are the real uses of bicycles in contemporary cities, with or without such a system? To answer these questions, the paper starts with a literature review on bicycle in the city, to draw lessons from recent experiences of bike sharing systems. It then discusses the two cases of Lyon and Lille, which never had a bike sharing system on its own. The evolution of bicycle use is measured with a comparison of household transportation surveys in Lyon (1995 and 1998) and Lille (1998 and 2006). In both cities, the analysis reveals a rise in the proportion of healthiest citizens among urban bikers, as well as a return of bikes in dense areas. Bike sharing systems are part of such tendencies. They support them, but should not become a panacea for policies supporting bike use in the city.     

基于蚁群算法的公共自行车站间调度优化

公共自行车系统在实际运行中存在借车难、还车难等问题,站间自行车调度不合理、不及时是主要原因。根据自行车调度的实际情况,考虑公共自行车系统特殊的调度车容量约束和下一站点补给约束,建立公共自行车站间调度的数学模型。通过改进常规旅行商问题求解的蚁群算法,以满足自行车调度的约束条件。在Matlab中编程实现改进的蚁群算法,并以武汉市关山光谷片区的24个自行车站点为例,用改进的蚁群算法求解调度回路,结果表明该算法可以求解得到最优调度回路。     

电动自行车太阳能充电系统设计

太阳能取之不尽、用之不竭,利用太阳能不会对环境造成任何不利影响,是可以替代石油、煤炭的经济环保的绿色能源。将太阳能应用于电动自行车等交通工具有很高的实用价值。本课题研究国内外太阳能电动自行车发展现状,结合自制电动自行车太阳能充电系统,分析、验证太阳能充电系统在电动自行车上应用的可行性与实用性。     

Development of an experimental methodology to evaluate the influence of a bamboo frame on the bicycle ride comfort

In the current environment of increased emphasis on sustainable transport, there is manifold increase in the use of bicycles for urban transport. One concern which might restrict the use is the ride comfort and fatigue. There has been limited research in addressing the difficulty in bicycle ride comfort quantification. The current study aims to develop a methodology to quantify bicycle discomfort so that performance of bicycles constructed from bamboo and aluminium alloy can be compared. Experimentally obtained frequency response functions are used to establish a relation between the road input and the seat and rider response. A bicycle track input profile based on standard road profiles is created so as to estimate the acceleration responses. The whole-body-vibration frequency weighting is applied to quantify the perception of vibration intensity so that eventual discomfort ranking can be obtained. The measured frequency response functions provide an insight into the effect of frame dynamics on the overall resonant behaviour of the bicycles. The beneficial effect of frame compliance and damping on lower modes of vibration is very clear in the case of bamboo frame, in turn affecting seat and rider response. In the bamboo frame, because of multiple resonances, the frequency response of the handlebar is smaller at higher frequencies suggesting effective isolation. Further improvements may have come from the joints made from natural composites. Overall, based on the comparative analysis and the methodology developed, bamboo frame shows significant improvement in ride comfort performance compared with the aluminium frame.     

考虑时空分布特征的混合自行车流元胞自动机模型仿真方法

针对非机动车交通流中传统元胞自动机模型主观定义时空参数,粗略划分自行车虚拟车道,导致仿真精度偏差的问题,构建了精细元胞自动机模型.基于NaSch模型的更新规则,考虑二维空间内异质自行车间的错位冲突及动态换道行为特征,细化了模型网格密度及模拟时间步长.产生换道需求的自行车可以换至满足安全侧向换道条件及前行需求条件的横向位...     

交通暴露与土地利用模式对社区COVID-19传播风险的影响

为揭示交通暴露和土地利用层面各因素对新型冠状病毒肺炎（COVID-19）疫情在社区尺度传播风险的影响，以A市315个小区的1 947例COVID-19确诊数据为研究样本，利用ArcGIS平台的地理编码、核密度分析、空间统计和网络分析等方法，基于道路网络、公交网络、城市POI和中国GDP/人口空间分布的公里网格数据，获取有病例小区500 m缓冲区范围内表征交通暴露和土地利用的14项具体指标。在此基础上，采用小区的COVID-19确诊人数作为解释变量，同时考虑交通暴露层面变量（路网密度、设施邻近度）和土地利用层面变量（混合度、使用强度），运用经典全局泊松回归和变系数地理加权泊松回归（GWPR）2种方法建立模型并进行实证对比分析。研究结果表明：考虑空间异质性的GWPR模型具有更高拟合优度和解释度；道路密度、公交线网密度、CBD邻近度、建筑密度、人口密度和土地价值与小区COVID-19传播风险呈显著正相关；出入口邻近度、绿地公园邻近度和土地利用混合度变量则在GWR模型中表现出随空间位置的改变呈现显著正负2种影响效果；人口密度、土地价值、绿地公园邻近度和土地利用混合度对小区COVID-19传播风险的影响程度要高于其他变量。因此，城市空间要素不仅会影响非传染性的病发风险，同时也与传染性疾病的传播风险显著相关，所得结果可为通过土地利用、城市交通规划等手段降低流行病发生的潜在风险提供参考。     

基于细节层次模型的公共自行车调度方法

公共自行车系统作为城市公共交通的重要组成部分，对于缓解城市交通拥堵和建设低碳、环保的出行体系起到了积极的作用。然而，由于公共自行车系统的借还车需求在时间和空间分布上存在不均衡性，在使用公共自行车时，经常遇到“借车难”或者“还车难”的问题，使得出行者不得不放弃使用公共自行车出行。为了有效地提升出行者借还公共自行车的成功率，研究了1种基于细节层次模型的自行车调度方法。基于公共自行车站点之间的相似度，采用谱聚类算法对站点进行层次划分，形成基于空间范围（即公共自行车站点所占据的地理空间区域）的站点簇；在每个划分层级上统计不同簇之间的自行车借/还需求，结合遗传算法对调度车辆的运输路径进行求解；将不同层级上的调度方案叠加，形成1种调度粒度由粗到细的自行车调度方案。通过对比实验证明:基于细节层次模型的公共自行车调度方法较传统方法减少了42.70%的调度路径，进而减少了相应的调度时间。      

Cycling in sub-Saharan African cities: Differences and similarities with developed world cities

Cycling is a vital transport mode for many of the Sub-Saharan African (SSA) cities given the limited transport options that exist. Despite its enormous commuting importance in SSA cities, little scientific research has attempted to identify key factors influencing cycling adoption, and most existing cycling promotional initiatives are often not contextualised to the African cities. To underpin appropriate incentives to promote bicycle commuting, this study conducts a literature review to identify key determinants of bicycle use in SSA cities. Moreover, it identifies key differences and similarities with cycling studies from the developed world cities (DWC). A survey of relevant literature was conducted through the Web of Science, Scopus, PubMed and Google scholar. This allowed gathering 61 relevant empirical study materials that helped to identify main factors influencing cycling in both SSA and DWC urban contexts, based on the socio-economic, built-environment, weather conditions and environmental and attitudinal factors. The results found that the vast list of factors influencing cycling, such as gender, education level, income, street signage, road encroachment, weather change, travel distance, the opportunity for flexible jobs and image prestige present a deep difference between studies in the two urban contexts. Street lighting, rain and tree cover present more consensual understanding among researchers in both urban contexts. This study reinforces that knowledge on cycling and its promotional initiatives should not be generalized, but rather be focused on the contextual setting of a particular city. In review of the past studies the limitation observed is that some specific characteristics of cycling in SSA cities such as the use of bicycle for commercial purpose is not covered in most cycling literature from the DWC. Given the observed contextual differences between cities from SSA and DWC, the study suggests the need for further research in quantifying and comparing the strength of the similarities and differences in cycling behaviour influences.     

Identification of the mechanical properties of bicycle tyres for modelling of bicycle dynamics

Advanced simulation of the stability and handling properties of bicycles requires detailed road–tyre contact models. In order to develop these models, in this study, four bicycle tyres are tested by means of a rotating disc machine with the aim of measuring the components of tyre forces and torques that influence the safety and handling of bicycles. The effect of inflation pressure and tyre load is analysed. The measured properties of bicycle tyres are compared with those of motorcycle tyres.     

城市居民使用共享单车意向研究——以合肥为例

为了探究共享单车使用意向的影响因素和因素间的作用关系,基于计划行为理论(TPB)构建了关于态度、主观规范、感知愉悦、灵活便捷和行为意向等潜变量的计划行为理论扩展模型.通过对问卷调查数据的信度和效度的分析,构建了共享单车使用意向的结构方程模型(SEM),得到各影响因素间的关系路径.结果表明,TPB理论可以很好地解释居民使用共享单车的行为意向,在共享单车的使用意向影响因素中,主观规范的影响最为显著,态度居其次,再次是感知愉悦,而灵活便捷对行为意向的影响作用相对较弱.      

On the influence of tyre and structural properties on the stability of bicycles

In recent years the Whipple Carvallo Bicycle Model has been extended to analyse high speed stability of bicycles. Various researchers have developed models taking into account the effects of front frame compliance and tyre properties, nonetheless, a systematic analysis has not been yet carried out. This paper aims at analysing parametrically the influence of front frame compliance and tyre properties on the open loop stability of bicycles. Some indexes based on the eigenvalues of the dynamic system are defined to evaluate quantitatively bicycle stability. The parametric analysis is carried out with a factorial design approach to determine the most influential parameters. A commuting and a racing bicycle are considered and numerical results show different effects of the various parameters on each bicycle. In the commuting bicycle, the tyre properties have greater influence than front frame compliance, and the weave mode has the main effect on stability. Conversely, in the racing bicycle, the front frame compliance parameters have greater influence than tyre properties, and the wobble mode has the main effect on stability.     

共享单车用户骑行起讫点时空特征分析

针对共享单车的供需失衡、分布不均问题，研究了共享单车用户骑行起讫点的聚集区分布以及不同区域的骑行时间特征，为共享单车的调度运营提供理论支撑。基于用户的骑行订单数据，采用均值漂移算法对骑行起讫点进行聚类学习，得到共享单车的骑行聚集区分布；随后采用spearman相关系数来衡量骑行时间特征的相似度，对不同骑行聚集区的借车与还车量的累计差值的时间序列曲线进行聚类处理，划分出6类典型的骑行特征，并对不同骑行特征所在地的兴趣点（POI）进行因子分析，结果表明:在空间上，共享单车的骑行聚集区的空间分布与所在区域的城市路网的布局形式存在较大关联，不同时间段的骑行聚集区的分布大致相同，仅在出行量上存在差异。骑行聚集区的骑行特征与土地利用性质之间存在相关性，例如，对于骑行特征为1天内借车量小于还车量的骑行聚集区，其主导因子为商业用地，占比为0.4；对于1天内用户的借车量大于还车量的骑行聚集区，其主导因子为住宅用地，占比为0.57。多种用地性质混合的区域，借还车的差值较小且易产生波动。此外，同一类型的骑行时间特征的主导因子占比在工作日与非工作日会产生变化，同一区域的骑行时间特征在工作日与非工作日存在差异。      

Large motion mountain biking dynamics

A bond graph model of a mountain bike and rider is created to develop baseline predictions for the performance of mountain bikes during large excursion maneuvers such as drops, jumps, crashes and rough terrain riding. The model assumes planar dynamics, a hard-tail (front suspension only) bicycle and a rider fixed to the bicycle. An algorithm is developed to allow tracking of a virtual tire-ground contact point for events that separate the wheels from the ground. This model would be most applicable to novice mountain bikers who maintain a nearly rigid relationship between their body and the bicycle as opposed to experienced riders who are versed in controlling the bicycle independent of the body. Simulations of a steep drop are performed for various initial conditions to qualitatively validate the predictions of the model. Results from this model are to be compared to experimental data and more complex models in later research, particularly models including a separate rider. The overarching goals of the research are to examine and understand the dynamics and control of interactions between a cyclist and mountain bike. Specific goals are to understand the improvement in performance afforded by an experienced rider, to hypothesize human control algorithms that allow riders to perform manoeuvres well and safely, to predict structural bike and body forces from these maneuvers and to quantify performance differences between hard-tail and full suspension bicycles.     

A mechanism to enhance bicycle conspicuity and visibility and increase detection distances: New insights into bicycle safety

Poor sensory conspicuity and poor visibility of bicycles are key factors that correlate strongly with bicycle-vehicle accidents. Although researchers have explored how to improve detection distances, i.e., the distances from which bicycles can be recognized by other road users, there is a dearth of research on ways to signal bicyclists' presence on the road. This study investigates how to enhance, at minimum cost, the level of visibility and sensory conspicuity of bicycles; it also considers ways to signal their presence to other road users, without necessitating any active behavior by bicyclists themselves. In the first study, the level of visibility of 6 rear-end components of bicycles was analyzed according to Adrian's model; the sensory conspicuity of these same components was analyzed via respondent perceptions in conditions of sunlight, twilight with no car headlights, twilight with car headlights, and night with car headlights. The level of visibility and sensory conspicuity of the 6 rear-end components were compared with considering angular size of the components under 4 lighting conditions. The level of visibility of the rear fender was good under sunlight and night-time conditions; in other conditions, the level of visibility was directly affected by painting the fender a silver color with reflectivity and also by the fender's angular size. However, the rear tire, among the 6 components tested, had a higher visible area when used with a short fender; it also produced rotational effects during riding conditions with no extra effort by the cyclists. In the second study, adhesive tape with specific patterns and 6 different color combinations were applied to the rear tire of a bicycle under the same lighting conditions, with the aim of creating a strong signal of the bicycle's presence for other road users. Among the 6 combinations, white stripes overlaid on the color red provide an optimal combination in terms of detection distance. The mean detection distance of white stripes on red in sunlight was 138.67 m, 94.67 m in twilight without car headlights, 94 m in twilight with car headlights, and 53.67 m at night with car headlights. In addition, this combination strongly signals the presence of the bicycle to other road users with no extra effort by the cyclists, thereby reducing the likelihood of drivers looking but failing to see bicycles. In sum, the study recommends that bicyclists install white stripes overlaid on red, in order to increase visibility and conspicuity and signal the presence of their bicycles, thereby reducing the likelihood of cyclist-vehicle collisions.     

Large motion mountain biking dynamics

A bond graph model of a mountain bike and rider is created to develop baseline predictions for the performance of mountain bikes during large excursion maneuvers such as drops, jumps, crashes and rough terrain riding. The model assumes planar dynamics, a hard-tail (front suspension only) bicycle and a rider fixed to the bicycle. An algorithm is developed to allow tracking of a virtual tire-ground contact point for events that separate the wheels from the ground. This model would be most applicable to novice mountain bikers who maintain a nearly rigid relationship between their body and the bicycle as opposed to experienced riders who are versed in controlling the bicycle independent of the body. Simulations of a steep drop are performed for various initial conditions to qualitatively validate the predictions of the model. Results from this model are to be compared to experimental data and more complex models in later research, particularly models including a separate rider. The overarching goals of the research are to examine and understand the dynamics and control of interactions between a cyclist and mountain bike. Specific goals are to understand the improvement in performance afforded by an experienced rider, to hypothesize human control algorithms that allow riders to perform manoeuvres well and safely, to predict structural bike and body forces from these maneuvers and to quantify performance differences between hard-tail and full suspension bicycles.