基于ADAMS的管道内检测器里程轮碰撞分析及模拟

进行管道内检测时,里程轮经常与管壁上的焊缝发生碰撞,形成测量误差。通过数学建模和ADAMS仿真分析,判断里程轮的平动速度与几何参数、焊缝尺寸、弹簧力对测量结果的影响。结果表明:增大里程轮平动速度、半径、宽度以及焊缝的尺寸,都会增大测量误差;里程轮初始速度小时,测量距离大于实际距离,里程轮初始速度大时,测量距离小于实际距离;弹簧力在一定的范围内,随着力值的增加,测量误差会减小,当超过这个范围继续增大力值时,测量误差会增大。     

管道地理坐标在内检测缺陷定位中的应用

文中阐述了管道地理坐标在内检测缺陷定位中的应用方法。首先建立基于APDM的内检测数据库,通过特征点的匹配,利用线性拉伸算法实现管道地理坐标与内检测里程的对齐与校准,精确计算内检测缺陷点的三维坐标,实现管道地理坐标与内检测里程统一,并通过内检测维护系统进行可视化展示。校准成果有助于缺陷点的开挖修复,保障管道的安全运营。以实际应用案例为例,详细说明管道地理坐标在内检测缺陷精确定位中的作用及应用方法,通过开挖验证说明缺陷定位精度控制在0.5 m以内。     

长输管道缺陷定位方法研究与应用

文中介绍了常见的2种缺陷定位方法,并详细对比分析了2种方法的实现过程及应用效果。通过内检测一维里程定位的方法简单快捷,成本低廉,但精度较低,受限较多;通过管道地理坐标与内检测一维里程相互校准、对齐与拉伸的方法周期较长、成本较高,但适用更广,精度可达到0.1 m。     

管道内检测器里程轮信号优选算法的设计与实现

阐述了管道内检测器里程计量模块的工作原理,提出了一种新的里程轮信号优选算法,设计了单片机控制系统,编制该算法程序,并用实验验证了该里程脉冲优选算法,给出实验数据。结果表明,该系统可以高效、准确地选择最佳里程轮脉冲信号。     

基于FPGA的里程轮信号优选算法设计

文中通过对里程信号产生机理进行分析,提出了一种基于FPGA架构的里程优选算法,给出了实现算法的硬件架构图,并设计相应硬件电路和模拟实验。结果表明:该算法可以对3个里程轮脉冲信号进行优选采集,当里程轮处于超速或者停转状态时也能输出正确的脉冲信号。     

衡量出租车供求的三大指标——里程利用率、车辆满载率、万人拥有量

里程利用率;指营业里程与行驶里程之比,一般以一辆车为单位,公式为:里程利用率=营业里程(公里)/行驶里程(公里)×100％这一指标反映车辆载客效率,如果比例高,说明车辆行驶中载客比例高,空驶比较低,对于要车的乘客来说可供租用的车辆不多,乘客等待时间增加,说明供求关系比例紧张。如果比例低,则车辆空驶比例高,乘客租用比较方便,但经营者的经济效益下降。作为以扬手招车为主要租车方式的出租汽车来说,以里程利用率作为衡量供求状况的主要指标,是     

数字

正2017年全国收费公路里程比上年净减少7356公里8月24日,交通运输部发布《2017年全国收费公路统计公报》,公布2017年全国收费公路里程构成、建设投资、收入支出等情况。截至2017年年末,全国收费公路里程16.37万公里,占公路总里程的3.4%,比上年下降0.2%;累计建设投资总额82343.9亿元,债务余额52843.5亿元,通行费收支缺口4026.5亿元。2017年,全国收费公路里程比上年年末净减少7356公里。     

中国和山东公路发展轨迹探求

主要阐述求解山东公路网发展轨迹所来用的理论、模型和方法，分别计算公路网总里程、高速公路里程、二级及二级以上公路里程以及各时期的相应值，以反映未来中国、山东省公路网的合理规模和结构。     

油气管道多轮内检测数据对齐算法研究及应用

由于多轮内检测外部不确定因素和误差的共同作用,多轮间里程数据存在一定差异,难以实现管道缺陷的对齐,人工开展内检测数据对齐的工作量巨大。文中针对管道多轮内检测数据对齐算法展开研究,建立相关模型以提高数据对齐工作效率,分析了解管道动态,保障管道安全运行。将算法应用于在役天然气管道的三轮内检测数据,实现了球阀、管件、弯头、环焊缝、缺陷等特征向基线的对齐,对齐结果与基线偏差精确至0.01 m。     

油田小口径管道内壁腐蚀检测技术

油田集输系统管道因内腐蚀穿孔造成停产事故和环境污染等,是油田安全生产的重大隐患,及早发现和判断管道内腐蚀情况越来越重要,为此研究开发了一种油田小口径管道内壁腐蚀检测技术.该技术采用长距离小口径管道内部视频检测车,通过视频观察和录像、里程记忆等系统的精密集成,实现了小口径管道长距离内壁表面状况检测.通过试验,获得令人满意...     

等里程间隔GM(1,1)模型在关角隧道6号斜井涌水量预测中的应用

在原始灰色GM(1,1)模型的基础上,通过运用等间距里程序列的分析方法建立模型,并对关角隧道6号斜井的涌水量进行了模拟预测。经检验,预测结果精度较高,对隧道工程涌水量的短期预测具有较大的实用价值。     

Relationships between highway capacity and induced vehicle travel

The theory of induced travel demand asserts that increases in highway capacity will induce additional growth in traffic. This can occur through a variety of behavioral mechanisms including mode shifts, route shifts, redistribution of trips, generation of new trips, and long run land use changes that create new trips and longer trips. The objective of this paper is to statistically test whether this effect exists and to empirically derive elasticity relationships between lane miles of road capacity and vehicle miles of travel (VMT). An analysis of US data on lane mileage and VMT by state is conducted. The data are disaggregated by road type (interstates, arterials, and collectors) as well as by urban and rural classifications. Various econometric specifications are tested using a fixed effect cross-sectional time series model and a set of equations by road type (using Zellner’s seemingly unrelated regression). Lane miles are found to generally have a statistically significant relationship with VMT of about 0.3–0.6 in the short run and between 0.7 and 1.0 in the long run. Elasticities are larger for models with more specific road types. A distributed lag model suggests a reasonable long-term lag structure. About 25% of VMT growth is estimated to be due to lane mile additions assuming historical rates of growth in road capacity. The results strongly support the hypothesis that added lane mileage can induce significant additional travel.     

Techniques for the inference of mileage rates from MOT data

Abstract

Mathematical and computational techniques are developed for the processing and analysis of annual Ministry of Transport roadworthiness (MOT) test data that the UK Department for Transport has placed in the public domain. First, techniques are given that clean erroneous records and a linking procedure is provided that permits the inference of an individual vehicle's mileage between consecutive tests. Methods are then developed that analyse aggregate mileage totals, as a function of vehicle age, class and geography. The inference of aggregate mileage rates as a function of time is then considered.     

A choice experiment on alternative fuel vehicle preferences of private car owners in the Netherlands

This paper presents results of an online stated choice experiment on preferences of Dutch private car owners for alternative fuel vehicles (AFVs) and their characteristics. Results show that negative preferences for alternative fuel vehicles are large, especially for the electric and fuel cell car, mostly as a result of their limited driving range and considerable refueling times. Preference for AFVs increases considerably with improvements on driving range, refueling time and fuel availability. Negative AFV preferences remain, however, also with substantial improvements in AFV characteristics; the remaining willingness to accept is on average € 10,000–€ 20,000 per AFV. Results from a mixed logit model show that consumer preferences for AFVs and AFV characteristics are heterogeneous to a large extent, in particular for the electric car, additional detour time and fuel time for the electric and fuel cell car. An interaction model reveals that annual mileage is by far the most important factor that determines heterogeneity in preferences for the electric and fuel cell car. When annual mileage increases, the preference for electric and fuel cell cars decreases substantially, whilst the willingness to pay for driving range increases substantially. Other variables such as using the car for holidays abroad and the daily commute also appear to be relevant for car choice.     

The Contribution of Benefit-in-Kind Taxation Policy in Britain to the ‘Peak Car’ Phenomenon

Car use per person has historically grown year-on-year in Great Britain since the 1950s, with minor exceptions during fuel crises and times of economic recession. The ‘Peak Car’ hypothesis proposes that this historical trend no longer applies. The British National Travel Survey provides evidence of such an aggregate levelling off in car mileage per person since the mid-1990s, but further analysis shows that this is the result of counter trends netting out: in particular, a reduction in per capita male driving mileage being offset by a corresponding increase in female car driving mileage. A major contributory factor to the decline in male car use has been a sharp reduction in average company car mileage per person. This paper investigates this aspect in more detail. Use of company cars fell sharply in Britain from the 1990s up to the 2008 recession. Over the same period, taxation policy towards company cars became more onerous, with increasing levels of taxation on the benefit-in-kind value of the ownership of a company car and on the provision of free fuel for private use. The paper sets out the changes in taxation policy affecting company cars in the UK, and looks at the associated reductions in company car ownership (including free fuel) and patterns of use. It goes on to look in more detail at which groups of the population have kept company cars and in which parts of the country they have been most used, and how these patterns have changed over time. A preliminary investigation is also made of possible substitution effects between company car and personal car driving and between company car use and rail travel. Clearly, the role of the company car is only one of many factors that are contributing to aggregate changes in levels of car use in Great Britain, alongside demographic changes and a wide range of policy initiatives. But, company car use cannot fall below zero, so the effect of declining year-on-year company car mileage suppressing overall car traffic levels cannot continue indefinitely.     

Transportation of hazardous materials on Arizona's low volume roads

This paper attempts to address the issue of transporting hazardous materials and the question whether this activity constitutes a significant problem on Arizona's low volume roads. Problems related to lack of data required for most of existing risk assessment models are discussed. A preliminary risk assessment, conducted by the use of a screening model, attested that of the total state low volume road mileage, only 30% may need further, and more detailed, hazardous materials transportation risk analysis. The remaining 70% is currently free of any significant risk.     

Unbalanced development of inter-provincial high-grade highway in China: Decomposing the Gini coefficient

This study discusses the unbalanced development of Chinese inter-provincial high-grade highway from 1997 to 2013. It does so from the viewpoint of the inter-provincial Gini coefficient based on per capita mileage of high-grade highway, which is decomposed according to such dimensions as the increment of the Gini coefficient, the Gini coefficient of different types of high-grade highway, and the Gini coefficient between and within inland and coastal areas. The Gini coefficient of China’s per capita mileage of inter-provincial high-grade highway shows a declining trend year by year. According to the results from the decomposition of the contribution rate of different types of high-grade highway, the unbalanced development of inter-provincial high-grade highway is caused mainly by that of first- and second-grade highway. According to the results from the decomposition related to the increment of the Gini coefficient of China’s per capita mileage of inter-provincial high-grade highway, the decrease of the Gini coefficient from 1997 to 2013 was mainly the result of balanced distribution of high-grade highway among regions in China. According to the results from the decomposition of the Gini coefficient between and within inland and coastal areas, the unbalanced development of inter-provincial high-grade highway in China from 1997 to 2013 was caused mainly by the unbalanced development of inter-provincial high-grade highway in inland areas. Therefore, the authors argue that the government should pay more attention to protecting the environment and providing a suitable scale of highway network, which could promote long-term sustainable development.     

Assessing the cost-optimal mileage of medium-duty electric vehicles with a numeric simulation approach

Electric freight vehicles have the potential to mitigate local urban road freight transport emissions, but their numbers are still insignificant. Logistics companies often consider electric vehicles as too costly compared to vehicles powered by combustion engines. Research within the body of the current literature suggests that increasing the driven mileage can enhance the competitiveness of electric freight vehicles. In this paper we develop a numeric simulation approach to analyze the cost-optimal balance between a high utilization of medium-duty electric vehicles – which often have low operational costs – and the common requirement that their batteries will need expensive replacements. Our work relies on empirical findings of the real-world energy consumption from a large German field test with medium-duty electric vehicles. Our results suggest that increasing the range to the technical maximum by intermediate (quick) charging and multi-shift usage is not the most cost-efficient strategy in every case. A low daily mileage is more cost-efficient at high energy prices or consumptions, relative to diesel prices or consumptions, or if the battery is not safeguarded by a long warranty. In practical applications our model may help companies to choose the most suitable electric vehicle for the application purpose or the optimal trip length from a given set of options. For policymakers, our analysis provides insights on the relevant parameters that may either reduce the cost gap at lower daily mileages, or increase the utilization of medium-duty electric vehicles, in order to abate the negative impact of urban road freight transport on the environment.     

Improvement in the estimation and back-extrapolation of CO2 emissions from the Irish road transport sector using a bottom-up data modelling approach

Road transport is a major source of CO₂ emissions in Ireland and accounts for almost 96% of the total CO₂ emissions from the transport sector. Following the recent adopted UNFCCC reporting guidelines on annual inventories [24/CP.19], this study applied the 2006 IPCC Guidelines for National Greenhouse Gas Inventories (2006 IPCC GLs) tier 3 approach to estimate CO₂ emissions from road transport at the vehicle category level, for the first time in Ireland. For this, disaggregated datasets were prepared based on year of vehicle registration and mileage since registration of the vehicle. Such an approach provided a more realistic national scenario in comparison to the use of average mileage degradation in emission calculations. This investigation comprised a recalculation of previous emissions estimates (1990–2012) and an estimation of CO₂ emissions in 2013 using a previously unavailable level of data disaggregation for vehicle mileage as well as using vehicle class specific data and an improved bottom-up estimation methodology in COPERT. Historic vehicle fleet data were restructured, annual mileage data were estimated in relation to the fleet data and back extrapolated using a regression approach.The results showed that the mileage degradation was not only subject to fuel technology, engine size, and age but also the emissions class and vehicle category. It was also observed that the disaggregated level of data provided a different CO₂ emissions split among the vehicle categories than that of previous estimations which were based on an aggregated level of data. Previous emissions inventories (1990–2012) were shown to have underestimated the share from diesel fuelled passenger cars by more than 56% in 2012. Diesel fuelled passenger cars were also found to account for the majority of CO₂ emissions from road transport activities in Ireland in 2013. The level and trend assessment showed that emissions from Euro-II and Euro-III classed vehicles especially for passenger cars, which have a significant contribution to the total emission in 2013 have caused an increase in fleet level emissions in Ireland. In addition, the results also showed that the emissions share from Light Duty Vehicles and Heavy Duty Vehicles were overestimated by previous investigations. This paper highlights the importance of the resolution of data used in emissions inventory preparation which may impact upon future projections and policy formulation. The findings of this investigation are also discussed in relation their implications for road transport policy, including carbon taxation and future policy options aimed at achieving EU emissions target in 2020.