输运流体海洋立管的动力特性

从流体的动量方程出发,考虑流体和管道的耦合,推导出输运流体海洋立管的偏微分运动方程。用Hermite插值函数和Galerkin法离散运动方程建立海洋立管动力运动的有限元模型。然后,利用该模型研究管内气柱流对固有频率的影响。计算结果表明:立管内出现气柱流时,固有频率随气柱位置的不同而明显变化。     

往复压缩机管道振动的消减

针对一台往复压缩机管系振动十分强烈的情况,进行了振动测试,并用ANSYS软件计算管系的结构固有频率、气柱固有频率、压力脉动和振动幅值,分析确定了管系振动的原因是共振,提出了采取增加支撑改变管系结构固有频率的减振措施。模拟计算结果表明减振效果明显。     

基于流固耦合的气液两相流管道振动特性分析

气液两相流管道容易发生振动问题,为确保其安全运行,有必要对其进行振动特性分析。根据考虑流固耦合作用的管道前两阶固有频率表达式,运用Matlab软件编程计算管道结构参数和流体参数对管道结构固有频率的影响。结果表明,考虑流固耦合作用时管道结构的固有频率下降明显,固有频率随壁厚和截面含气率的增加而增加,固有频率随管道长度、流体密度以及天然气流速的增加而降低。在实际气液两相流混输管道工程中应重视流固耦合作用对结构固有频率的影响。     

压缩机进口管路球阀旁通细管的振动分析

为了研究某天然气压气站内压缩机进口管路球阀旁通细管的异常振动原因,使用振动测试仪器,确认旁通细管振动对应的工况,并测试振动幅值和频率特征。使用ANSYS和Fluent软件结合的方式,分析细管产生振动的原因,并对比分析理论计算结果与实际测试结果,验证分析的准确性。最后提出旁通细管的减振措施。研究表明:管路的压力脉动频率、管路内气柱的固有频率、管道的固有频率重合时,易产生振动。建设新天然气线路时,需仔细校核新管道输送线路对已有管道输送线路的影响,避免出现振动现象。     

旋转波纹管的固有频率计算

提出用有限单元法计算波纹管的固有频率，将波纹管离散为环锥壳单元，单元之间以结点圆相连结，推导出波纹管固有频率计算的特征方程，分析和算例表明，该法能方便有效地计算波纹管的固有频频率，可为工程中波纹管的设计提供理论依据。     

天然气站场管道应力分析

文中以西气东输二线库米什压气站为例,运用CAESARⅡ有限元分析软件对压气站管道进行静态分析及动态分析。其中,静态分析校核了管道模型在持续工况及膨胀工况下的节点应力,并计算出压缩机进出口管道在操作工况下的位移和约束力。由校核结果可知,管道系统应力均在许用范围内,最大应力节点为压缩机出口管线的放空阀处。动态分析求解了管道的前5阶固有频率,并针对固有频率较低的位置,提出了相应的措施,最终将管道的固有频率提高到11.277 Hz,使管道的振动控制在合理范围内。     

干线石油管道振动的ANSYS分析

针对常见的管道振动情况,通过分析得出其主要原因是管系结构固有频率与激发主频率相近而造成共振.管道系统振动的原因主要有两方面:介质对管道系统产生的振动力,即激发信号,如分支节点部位产生的振动力;对激发信号的响应,其响应除了和激发信号的波形有关外,还和管道系统本身的特征,即系统的刚度、质量及其配置等情况有关.通过理论计算得...     

基于ANSYS/Workbench的空调配管流固耦合分析

空调配管振动是引起整机振动的主要原因之一。为了减小配管振动,需要合理设计配管结构,以避免因配管结构固有频率与激发频率接近而发生机械共振。空调配管内通有高温高压气体,对配管固有频率的影响不可忽略。文中利用ANSYS/Workbench计算了配管在流固耦合情况下的固有频率,并与空管固有频率进行对比,显示了二者的差异性,为空调配管前期设计提供了参考。     

混输管路压降计算方法在工程上的应用

混输管路在油田的地面集输系统中应用日益广泛,而混输管路压降计算对于管路经济管径选取起决定作用.文中对气液两相混输管路压降计算简单总结,对均相流模型、分相流模型、流型模型的代表性计算方法进行了介绍,并通过具体工程实例对工程设计中常用的混输压降计算方法进行了对比.采用常用的多相流模拟软件进行校核,得出Beggs - Bri...     

管道试压过程稳压时间的理论研究

文中把管道的泄漏点理想化为泄漏孔,运用流体力学原理,建立了管道试压稳压时间的计算模型,并以西气东输管线为例,利用该模型进行了计算.结果表明:水压试验稳压时间与管容、管内含气量关系较大.气试压稳压时间随内压、管容而不同.根据计算结果,确定了试压稳压时间的建议值.     

An assessment of UK drivers’ attitudes regarding the forthcoming ban on the sale of petrol and diesel vehicles

The purpose of the study was to predict how drivers of petrol or diesel cars might vote in a ‘Yes/No’ referendum concerning the UK government’s decision to ban from 2040 onwards the sale of all new non-electric vehicles. Five main factors were hypothesised to influence voting intention: a person’s (i) level of environmental concern, (ii) attitude towards electric cars (measured via an Implicit Association Test), (iii) belief about the importance of air pollution, (iv) driving requirements, and (v) reaction to the cost of the ban to the individual (assessed using a contingency valuation approach). The study also examined possible determinants of attitudes to electric vehicles, e.g., whether an individual was a ‘technology enthusiast’, had prior knowledge of and searched for knowledge about electric vehicles, and whether a person had played an online game where the player assumed the identity of an electric car driver. A structural equation model was developed and tested on a sample of 675 UK drivers, none of whom had ever owned or driven an electric car. The results suggested a good fit of the model to the data, except that neither environmental concern nor belief in the importance of clean air affected attitude to electric cars. Also, high levels of environmental concern did not motivate people to search for knowledge about electric vehicles. Social marketing campaigns that will be needed to precede the ban should focus on its health benefits, and not target particular age groups, gender, or whether a participant had children.     

Spontaneous emergence versus technology management in sustainable mobility transitions: Electric bicycles in China

This paper describes and seeks to understand the scale of the electric bicycle (electric two-wheeler) market in China, and to begin to explain its emergence with a view to outlining the prospects for learning from this case for applications in other countries around the world. Drawing on secondary data from Chinese government sources, electric bicycle industry websites, Chinese media sites and other sources, this exploratory paper positions the development of the electric bicycle market as occurring largely in the absence of positive policy intervention – in stark contrast to the nurturing afforded the electric car sector world-wide. The paper develops a multi-scalar perspective of transitions theory in an institutional setting, with examples drawn from Beijing and Fuzhou, to explain the processes of change outside of the traditional reference context of technology policy and management. It is concluded that transitions theory has a greater flexibility and adaptability as an explanatory framework than previously shown, but empirically the electric two-wheeler is a weakly-embedded alternative to mainstream automobility.     

Adoption intentions for micro-mobility – Insights from electric scooter sharing in Taiwan

Micro-mobility may alleviate a number of challenges facing big cities today, and offer a pathway toward more sustainable urban transportation. This research investigates what factors influence university students’ intention to use an electric scooter sharing service. A theoretical framework adapting the theory of planned behaviour was used. Survey responses from 471 university students in Taiwan were collected. Data were analysed using factor analysis and structural equation modelling. Respondents with different levels of usage intention and in different stages of behavioural change display distinct reasoning patterns. Lack of perceived compatibility with personal values, mobility needs and life-style particularly drives students with low usage intention and pre-contemplators, who show signs of “green hypocrisy”. Awareness-knowledge about the sharing system and environmental values influence the formation of usage intention in indirect ways. This study is intended to be a reference for subsequent conceptual and empirical work on e-scooter sharing in particular, and shared mobility with other types of powered two-wheelers.     

杂散电流排流设施有效性评价研究

随着交直流电气化铁路、高压输电线路的大量兴建,管道不可避免受到临近电气化设施的干扰。排除或者减缓杂散电流的主要途径是选择合适的杂散电流排流设施。国内目前应用的排流设施主要有极性排流器、钳位式排流器以及固态去耦合器。通过对这几种排流设施进行的现场测试与评价,总结出了每种排流方式的优点与局限性,可为今后不同干扰情况下选择合理的排流减缓方式提供依据。同时,结合现场实践,提出了杂散电流减缓的研究方向。     

Positive and negative spillover effects from electric car purchase to car use

This study reports the results of two online surveys conducted on buyers of conventional combustion engine cars compared to those of electric vehicles in Norway. The results show that electric cars are generally purchased as additional cars, do not contribute to a decrease in annual mileage if the old car is not substituted, and that electric car buyers use the car more often for their everyday mobility. Psychological determinants derived from the theory of planned behavior and the norm-activation theory show a high correlation between the purchase and use stages. Electric car buyers, have lower scores on many determinants of car use, especially awareness of consequences and close determinants of car use.     

An alternative model in traffic flow equations

The kinetic theory for traffic flow equations can be approached using the Grad’s method. This method, which is derived from the kinetic gas theory, was developed for the Paveri-Fontana equation when a special desired velocity model is assumed. A closure relation for the set of macroscopic equations is found when the density, the average velocity and the velocity variance are the relevant variables chosen to describe the system. Simulation results are also shown and a qualitative comparison with other models in the literature is presented.     

考虑科氏力影响的旋转Timoshenko梁的变结构控制分析

文章基于Hamilton变分原理,采用Timoshenko梁理论,给出了考虑科氏力影响的中心刚体一柔性梁系统的动力学方程,并应用弹性波与振动模态理论,确定了受科氏力影响的Timoshenko梁的振动模态。同时,结合变结构控制器设计原理,对比分析了考虑科氏力与不考虑科氏力时对旋转Timoshenko梁振动的影响。     

格拉管道顺序输送运行优化研究

不同油品依次沿一条管道顺序输送,是长距离输油管道的基本营运业务之一,其工况的运行优化具有重要的理论和工程意义。给出了表述油品“界面”处于管道某特殊点时全线压能平衡方程和各校核点动压的通用计算公式。根据格拉管道改造方案,以寻求最大输量为目标,对其进行了工况运行优化研究。在寻求最优调节方案时,采用了上游调节优先,先停运泵机组、后分配节流压力的方法。     

碳达峰背景下雄安电动货车减碳量测评研究

随着核电、风电等清洁能源的发展,纯电动车辆将成为绿色交通的主要发展方向。本文基于油耗法的方法原理构建雄安新区电动货车减碳测算模型,通过减碳测算模型估算雄安新区电动货车的减碳量,并对其产生的经济效益进行估算和社会效益进行分析。研究结果表明,雄安新区电动货车的年减碳量可观,减排效益明显。积极推进雄安新区物流运输工具能源消费结构的转型升级,不仅符合雄安新区建设的发展要求,而且对于加快区域碳达峰目标的实现具有至关重要的作用。     

使役条件下二轮电动车电池单次耐用性研究

本文通过理论和实验相结合的方法对使役条件下,在不同坡度、路面道路条件,不同充放电时间、制动次数、轮胎胎压、载重量等使用情况对二轮电动车电池的单次耐用性进行试验研究。结果发现,造成电机输出功率增加,放电电流增大的外部条件均会造成蓄电池容量减少,研究结果可指导二轮电动车车主合理科学使用二轮电动车。