Reaction characteristics of the diesel oxidation catalyst of particulate matters from the diffusion flame of a oiler burner

The objective of this experimental study is to investigate the characteristics of the size distribution and the number concentration of PM (particulate matters) emitted from the diffusion flame of a boiler burner, which has the same type of combustion as a diesel engine. This study is performed to investigate the emission characteristics of nanoparticles generated from diffusion combustion in diesel fuel, and it considered fuel factors and the reaction characteristics of the nanoparticles on the DOC (Diesel oxidation catalyst). The factors examined in this experiment included the sulfur content in the fuel, the blend of the diesel fuel containing biodiesel and bio-ethanol, and the concentration of engine oil (0.1% and 1.0%) blended with diesel fuel. The particle size distribution of the nanoparticles exhausted from the boiler burner was measured by an SMPS (scanning mobility particle sizer). The number concentration of PM that were smaller than 70 nm in diameter greatly increased in the rear of the DOC when fuel containing 250 ppm of sulfur was used. The experiment also suggested that the particle number concentration in both the front and rear of the DOC was lower when ULSD (ultra low sulfur diesel) fuel blended with biodiesel and bio-ethanol, which are oxygenated fuels, was used than when only ULSD fuel was used. The higher the content of engine oil in the fuel, the higher the particle number concentration was in the front and rear of the catalyst. When the first dilution air temperature is increased from 30°C to 180°C, the nanoparticle number concentration dramatically dropped in the rear of the catalyst when fuel containing 250 ppm of sulfur was used, while the particle size distribution remained almost the same when the fuel with engine oil was used.     

沉模薄壁管桩加固软土地基技术

振动沉模现浇混凝土薄壁管桩技术,可快速加固软土地基,具有承载力高、施工工艺简单、质量可靠、工效高和工程造价低等优点,具有良好的推广应用价值。     

Existence of urban-scale macroscopic fundamental diagrams: Some experimental findings

A field experiment in Yokohama (Japan) reveals that a macroscopic fundamental diagram (MFD) linking space-mean flow, density and speed exists on a large urban area. The experiment used a combination of fixed detectors and floating vehicle probes as sensors. It was observed that when the somewhat chaotic scatter-plots of speed vs. density from individual fixed detectors were aggregated the scatter nearly disappeared and points grouped neatly along a smoothly declining curve. This evidence suggests, but does not prove, that an MFD exists for the complete network because the fixed detectors only measure conditions in their proximity, which may not represent the whole network. Therefore, the analysis was enriched with data from GPS-equipped taxis, which covered the entire network. The new data were filtered to ensure that only full-taxi trips (i.e., representative of automobile trips) were retained in the sample. The space-mean speeds and densities at different times-of-day were then estimated for the whole study area using relevant parts of the detector and taxi data sets. These estimates were still found to lie close to a smoothly declining curve with deviations smaller than those of individual links – and entirely explained by experimental error. The analysis also revealed a fixed relation between the space-mean flows on the whole network, which are easy to estimate given the existence of an MFD, and the trip completion rates, which dynamically measure accessibility.     

公路超载的影响分析

目前,公路超载、超重车辆运输现象有所减少,但仍很普遍,本文从理论上综合分析了超载的问题现状与危害,提出了减少路面早期损坏的有效措施,供同行们参考。     

热管散热器在新型变流装置中的应用

针对传统的实体铝、铜散热器已经远不能满足大容量元件散热容量要求的现状,提出采用热管散热器的新思路,并阐述了热管的结构和特点。简要介绍了我国已利用热管开发的机车用新产品,预测热管散热器将有广泛的应用前景。     

开架式ROV动力匹配稳态与动态设计方法

本文针对开架式ROV的设计,提出一种将稳态匹配与动态匹配相结合的动力匹配研究方法。首先根据所设计的ROV,运用Fluent软件对其进行水阻力仿真,得出ROV在不同航速下的阻力,其次对螺旋桨进行特性分析,进而对比螺旋桨不同参数对推力和阻力匹配的影响,同时考虑螺旋桨功率与电机功率匹配,完成ROV的稳态匹配。最后加入动态分析得到最终的动力匹配,并证明其具有较好的运动稳定性以及机动性。     

Leisure mobility styles in Swiss conurbations: construction and empirical analysis

Leisure travel is the most difficult travel purpose to analyse due to the lack of fixed spatial and temporal referents and the consequent flexibility in patterns. This paper addresses lifestyles, social influence, and the travellers’ social networks, issues that have proved valuable for travel behaviour research in confronting the complexity of leisure travel. An approach for constructing leisure mobility styles, based on orientations towards leisure and mobility, will be presented first and then the hypotheses that transport behaviour can be better explained through analysis of leisure mobility styles will be tested. Multivariate analysis reveals that the leisure mobility style group makes a significant contribution towards clarifying variance for the activities ‘Visiting friends and relatives’, ‘Travel participation’, ‘Mode choice’, and ‘Travel distance for leisure’. The use of leisure mobility styles is most useful for developing practical intervention pointers where the in-group homogeneity of lifestyle should be addressed in greater detail.     

The bending vibration response and approximate calculation of elastic cylindrical shell

Useful structure characteristics of elastic cylindrical shells have led them to being widely applied in virtual projects, so it is important to conduct vibration research on the shells and find it＇s a simpler corresponding compact calculation method. Utilising the input and transfer point mobility of a thin plate structure, a theoretical expression of the cylindrical shell＇s bending vibration responsewas deduced and numerical simulations were done to simplify the theoretical expression within an acceptable error margin, greatly reducing the amount of computations. Furthermore, whole vibration response distributions of the cylindrical shell were analyzed. It was found thathe vibration energy propagates in helical form under mono-frequency excitation, while under bandwidth frequency excitation, it attenuates around in term of fluctuation. The axial attenuation rate of the vibration energy is larger than the circumferential attenuation rate.     

基于MAST的智慧公交优化调度研究

对客运需求较小且时空分布不均衡的城郊和乡村开设公交线路所面临问题分析的基础上,设计了一个利用移动互联网技术的城郊乡村智慧公交调度系统.简述了包括乘客信息交互模块、数据库、预测模块、调度决策支持模块等组成的系统结构及原理.在此基础上,分别建立发车计划模型和实时调度在线调整模型,采用遗传算法优化求解.最后,基于调度系统的历史信息及预约信息的实验结果表明,本运营方式能够提升服务水平,增加公交企业效益,且随预约乘客比例增加,该方式的优势愈加明显.     

Transport and equity in Latin America: a critical review of socially oriented accessibility assessments*

ABSTRACT

A growing concern for mobility-related social inclusion and equity is evident from both academic research and planning best practices. Scholarly research promotes accessibility as the main aim of transport planning, assuming it as the evaluative approach that better conveys how mobility contributes to individuals' well-being and participation in social life. Accessibility can be crucial to address the socio-spatial inequalities that characterise manifold settings across the world. Amongst them, Latin American countries have been keen in tackling such imbalances through mobility-related interventions, as the renowned cases of Curitiba, Medellin and Bogotá show. The widespread interest in mobility as both a cause and effect of social disparities has generated an increasing stream of work that examines Latin American settings through the lenses of accessibility. This paper aims at critically reviewing the growing scholarly works that, providing accessibility-based evaluations, has examined issues of transport and equity in Latin America. Proposing a novel conceptual framework that considers the underlying ethical stance, components of accessibility and implications for planning and policy, this work examines what approaches, features and indicators are present in the current literature, as well as what settings have been taken into consideration by scholarly research. Moreover, the review has an explicit operational interest, to define what indicators are relevant or missing to assess accessibility in the light of social concerns, as well as to consider the current and potential implications that such research findings have on transport planning and policy. The review highlights how a growing but still limited body of work has examined transport and equity in Latin America, suggesting academic, technical and operational avenues to enhance theoretical and practical approaches to the issue.