某型复杂变速器壳体的模态研究

首先分析了工作模态法的优点及其所用的随机子空间法理论;然后应用工作模态法对某型变速器复杂壳体的模态进行实验辨识,得到了壳体各阶的模态频率和振型。并利用有限元软件MSC.Patran和MSC.Nastran对壳体模态进行数值计算,通过实验模态和数值计算模态的对比,发现在低频段实验结果与数值计算结果较吻合,说明采用工作模态法能较精确地识别出壳体的低阶模态。     

学术语篇中情态模糊限制语及其评价意义研究

学术语篇常被认为以客观方式传递信息和表达观点．但其撰写者若要达到这种目标,并使语篇中的信息和观点能充分地被读者所认可或接受,需借用一定的语言表达手段．情态模糊限制语便是其中的表达手段之一．基于此,试从系统功能语言学中的评价理论出发,对学术语篇中情态模糊限制语及其评价意义进行研究．     

Policy implementation of multi-modal (shared) mobility: review of a supply-demand value proposition canvas

ABSTRACT

Urban mobility options have increased in recent years, assisted by the widespread availability of smart device software apps, geo-positioning technology, and convenient electronic financial transactions. Multi-modal shared mobility consists of public transit systems and shared mobilities that support first/last mile travel, denoting the capability of Mobility as a Service (MaaS), and to stimulate additional non-private car travel demand. This paper reviews the supply and demand sides of implementation of multi-modal shared mobility. It found that an abundance of shared modes of car, bike, and e-scooter that are linked to public transport, can improve transport accessibility to meet specific public preferences, reduce social inequality, and minimise dilemmas from the demand side. This study introduces government policy innovations and other supporting system to improve the implementation of multi-modal shared mobility. Government policies play a key role in supporting shared mobility and technology development. However, governments do not have much information about new products such as shared mobility, which creates difficulties in subsidising multi-modal shared mobility services and potentially leads to policy failures around shared mobility schemes. This study suggests that policy entrepreneurship in collaboration with other partners, policy innovation, and the notions of merit goods and second-best policymaking can enable policy initiatives towards multi-modal shared mobility and provide supporting arguments if policies encounter failures. Implementing multi-modal shared mobility requires a collaborative partnership for a paradigm shift: service providers and government must jointly set a merit-based business model, with the support of organisations to achieve improved infrastructure provision, and smart technology applications. The findings will assist the community, business providers and government policymakers to promote multi-modal shared mobility as a pathway towards more efficient, environmentally sustainable, and socially responsive mobility solutions.     

分体式台车在城际铁路明挖隧道中的应用

先简单叙述了分体式模板台车的安装、使用及校核过程,通过台车操作平台控制千斤顶油压调节模板形状,人工测量校核达到设计要求位置。随后阐述了分体式台车施工方法及施工控制要点,分别就侧墙施工与拱顶施工做了描述,重点描述了施工过程中防水施工采取的措施,总结了明挖隧道施工过程中分体式台车的使用经验,证明了分体式台车在安全、质量、进度和费用方面的可行性与可操作性,对类似工程提供借鉴。     

Optimization-based study of the location of park-and-ride facilities

Park-and-ride facilities are parking lots located on the periphery of cities to intercept car trips coming from the suburbs and diverting them to a transit system, thus playing a potentially important role in reducing traffic congestion and air pollution in urban areas. In this paper, we present a study carried out to shed light on where to install park-and-ride facilities in the city of Coimbra, central Portugal. Its main component is an optimization model which aims to determine the best possible locations for a given number of park-and-ride facilities under the objective of minimizing car use in the urban areas. The main result of the study is that the introduction of only three park-and-ride facilities could reduce car use in Coimbra's urban areas by 19%, an impact that would be very difficult to achieve through measures such as decreasing bus fares, increasing parking fees and/or increasing bus services.     

Modal split in offshore supply network under the objective of emissions minimization

We study modal split under the objective of emissions minimization in the transportation of cargo from centralized vendors in the oil and gas industry to decentralized supply bases on the Norwegian coast. The supply network includes direct road transport and a sea route along the coast. To gain insight into modal split decisions between road and sea transport from the shipper’s perspective multi-period mixed integer optimization models are formulated. Particularly the models give possibilities to examine how weekly demand patterns at supply bases, cargo commitments to sea transport, storage possibilities at supply bases, and shipper’s responsibility for a certain share of vessel capacity may effect the emissions and the modal split. Experiments on real data from an oil and gas company operating offshore show that the size of the share of vessel capacity and the possibility for storage at supply bases are the major determinants for a larger shift to environmentally friendly sea transport. The models can be used as means for making decisions regarding how a shipper can commit to sea transport to achieve less emissions.     

Short Sea Shipping in Supply Chains. A Strategic Assessment

The feasibility of implementing short sea shipping (SSS) between two specific ports has been typically approached on the operative level, in terms of time and cost for a specific origin–destination pair. This paper focuses on the strategic level. Particularly, its goal is to study the potential of SSS in different industrial sectors by analysing their freight-distribution strategies. To achieve the objective, some standard freight-distribution strategies are defined based on the requirements of the industry, the demand and the product being transported. The information is complemented with a survey of more than 100 Spanish companies distributing internationally. As a result it is concluded that there are economies of scale related to the size of the carrier (the ship) and its capacity to absorb the variability in demand. This potential increases with the cargo value. Additionally, a framework of supply/distribution chains is provided which can help to identify potential customers/sectors and the feasibility of new potential shipping lines. The value of this paper resides in its approach (strategic, instead of operational/tactical), and the solid groundwork point provided for future researchers.     

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.     

考虑交叉口影响的城市路网信号优化设计问题研究

基于城市路网交通间断流特性,本文将微观层面的信号交叉口延误计算方法引入宏观层面的平衡网络信号优化设计问题,构建了一个中观层面的城市路网交叉口信号优化设计双层规划模型,设计了基于遗传操作的优化算法。通过路网算例对模型及算法进行测试,并通过与微观、宏观层面的两种信号优化配时方法进行比较,验证所提出模型的优越性。     

基于动刚度和模态应变能的某车NVH性能改善研究

本文通过创建某车的白车身模型和带内饰车身模型,进行车身噪声传递函数分析,并结合车身的模态应变能分布情况和动刚度分析结果,查找并确定导致车内噪音较大的原因,并提出了几种优化方案,采用CAE方法选择最佳方案,经试验验证,最终改善车身的NVH性能。