用DM2计算路基填挖方量

本文介绍了实用的路基断面填挖方量计算软件DM2的特点、原理和使用方法。软件适合于铁路、公路施工现场的路基横断面测量和方量计算，并对二维断面测量和全站仪三维断面测量都有良好的支持。软件小巧，设置、操作方便。     

城市道路横断面设计方法研究

城市道路横断面设计的优劣决定着道路通行的安全和畅通。因此,从城市道路横断面的构成入手,分析了横断面的布置原则,并提出了城市道路横断面的设计方法,具有一定的理论和实际意义。     

HFETR二次水超声波流量偏小原因分析

在设备运行中发现HFETR二次冷却水超声波流量计测量值比文丘里式流量计偏低。为了满足冗余性、多样性的设计原则,对HFETR二次冷却水设计了两套不同原理的流量测量装置。从超声波流量计的原理分析出由于HFETR二次水含沙量高,造成声波传播速度比理想情况下水中的传播速度高,使超声波流量计测量的流量偏低。通过引入修正因子可以消除偏差。     

基于移动式X射线检测系统的管道壁厚测量方法

为解决移动式X射线管道检测系统中管道中心偏移引起的壁厚测量偏差问题,提出了一种管道壁厚测量方法.首先,在移动式X射线检测系统中获取投影图像;然后,使用U-Net神经网络处理投影图像以抑制噪声和伪影引起的干扰,从而准确提取管道内外径边缘等关键点的位置信息;最后,根据提出的基于偏心校正的管道壁厚计算方法得到管壁厚度.仿真和...     

GPS·RTK技术在省道316线高唐至聊城段工程中的应用

通过工作实践,结合其在省道316线高唐至聊城段工程测量中的应用,介绍了用GPS·RTK技术进行中线测量的方法,可以有效的提高作业效率和测量质量,介绍了RTK测量作业工程中的一些注意问题、RTK的技术优点、测量方面的局限性及今后发展方向.     

由测点坐标推算隧道断面开挖控制值的方法探讨

针对传统的采用极坐标放样已知坐标点的测量放样方法的不足,文章提出应用免棱镜全站仪测出任一点坐标,并采用通用的路线坐标计算公式和坐标变换算法,推算隧道断面开挖控制值的方法,可有效提高施工测量作业效率。     

小口径长距离钢顶管全自动测量技术研究

自动测量技术因其简单、省力省时、高精度等优势在顶管施工中得到了广泛应用。结合绍兴城北供水顶管工程,介绍了自动测量方案及其所用仪器,并通过顶进效率、顶进效果、顶进精度和进洞过程分析了自动测量技术对顶管施工的影响。现场施工数据和顶进效果表明,自动测量技术可以加快顶进效率、提升顶进效果、确保顶进精度以及保证精准进洞。     

市政道路旧路改造横断面设计分析

为解决市政道路旧路改造过程中的横断面设计问题,本文对市政道路旧路改造的横断面设计的重要性进行了分析,提出了基于安全性和功能性的横断面设计要点,以期为城市规划师、工程师等提供实用的参考。     

精密跨海三角高程测量代替二等水准测量的可行性尝试

鉴于用传统几何水准测量的方法进行高程传递存在效率低、受环境和地形因素影响大的问题,通过比较三角高程与普通水准测量的优劣之处,以及三角高程测量过程中利用数据自动采集软件自动采集数据的优势,研究了三角高程的量的误差来源及精度;同时以港珠澳大桥为背景,分析了TS30全站仪三角高程测量代替二等水准测量的可靠性与可行性,给出了提高三角高程测量的精度以及减弱误差方法的措施等。     

内河航运建设工程中工程造价控制的偏差及纠偏措施

文章利用文献研究法等方法,以内河航运建设工程平陆运河项目为例,从控制因素、检查因素两方面对内河航运建设工程中工程造价控制偏差因素进行分析,随后以偏差因素为导向提出纠偏措施。     

枝状天然气管网流动方程

过去使用的关联矩阵方法在描述枝状天然气管网流动方程时,没有考虑压气站的自耗气,这在一些需要准确描述这部分气量的模型中会产生不可避免的偏差.文中通过增加自耗气源向量的方法对此进行了改进,使得该方法可以完整地描述这部分天然气,能更加准确地对管网的结构和流动方程进行描述.     

The changing accuracy of traffic forecasts

Researchers have improved travel demand forecasting methods in recent decades but invested relatively little to understand their accuracy. A major barrier has been the lack of necessary data. We compiled the largest known database of traffic forecast accuracy, composed of forecast traffic, post-opening counts and project attributes for 1291 road projects in the United States and Europe. We compared measured versus forecast traffic and identified the factors associated with accuracy. We found measured traffic is on average 6% lower than forecast volumes, with a mean absolute deviation of 17% from the forecast. Higher volume roads, higher functional classes, shorter time spans, and the use of travel models all improved accuracy. Unemployment rates also affected accuracy—traffic would be 1% greater than forecast on average, rather than 6% lower, if we adjust for higher unemployment during the post-recession years (2008 to 2014). Forecast accuracy was not consistent over time: more recent forecasts were more accurate, and the mean deviation changed direction. Traffic on projects that opened from the 1980s through early 2000s was higher on average than forecast, while traffic on more recent projects was lower on average than forecast. This research provides insight into the degree of confidence that planners and policy makers can expect from traffic forecasts and suggests that we should view forecasts as a range of possible outcomes rather than a single expected outcome.

     

浅析清单报价中的偏差单价及修正

分析了错误的清单单价产生的影响,阐述偏差单价修正的必要性,通过两个案例探讨了偏差单价的修正方法。     

基于SVM的隧道衬砌空洞填充物雷达图像识别研究北大核心CSCD

衬砌背后空洞及其填充物对隧道结构安全具有重要影响,开展空洞探测识别对于结构安全评估和病害处置具有重要意义。首先采用室内试验和FDTD正演模拟相结合的方法,获得了空洞内填充空气、水、干砂、湿砂条件下的雷达图谱数据,并对不同填充物波形规律进行对比分析;然后,基于支持向量机算法对波形特征进行提取和分类识别,建立了一种空洞填充物的人工智能辨识方法。研究结果表明,采用傅里叶变换前的平均值、方差、平均绝对离差和傅里叶变换后的最大幅度值max(fft(X))四个统计量作为支持向量机的识别特征,可以有效区分出衬砌背后填充物的六种类型;当采取单一倾向数据时,识别准确率较好,六种物质二分类问题准确率均可以达到90%以上。     

探地雷达在隧道检测中里程偏差修正方法探讨

文章针对探地雷达在隧道质量检测中由于天线行走速度不一或检测人员打标记不及时产生的里程偏差,建立了检测里程与实际里程之间关系的数学模型,利用该模型对检测里程进行修正,可使检测结果回归到真实的里程.     

Second-order models and traffic data from mobile sensors

Mobile sensing enabled by GPS or smart phones has become an increasingly important source of traffic data. For sufficient coverage of the traffic stream, it is important to maintain a reasonable penetration rate of probe vehicles. From the standpoint of capturing higher-order traffic quantities such as acceleration/deceleration, emission and fuel consumption rates, it is desirable to examine the impact on the estimation accuracy of sampling frequency on vehicle position. Of the two issues raised above, the latter is rarely studied in the literature. This paper addresses the impact of both sampling frequency and penetration rate on mobile sensing of highway traffic. To capture inhomogeneous driving conditions and deviation of traffic from the equilibrium state, we employ the second-order phase transition model (PTM). Several data fusion schemes that incorporate vehicle trajectory data into the PTM are proposed. And, a case study of the NGSIM dataset is presented which shows the estimation results of various Eulerian and Lagrangian traffic quantities. The findings show that while first-order traffic quantities can be accurately estimated even with a low sampling frequency, higher-order traffic quantities, such as acceleration, deviation, and emission rate, tend to be misinterpreted due to insufficiently sampled vehicle locations. We also show that a correction factor approach has the potential to reduce the sensing error arising from low sampling frequency and penetration rate, making the estimation of higher-order quantities more robust against insufficient data coverage of the highway traffic.     

浅析鹿山大桥深水承台双壁钢围堰施工技术

文章以鹿山大桥深水承台双壁钢围堰施工技术为例,阐述大型桥梁深水承台双壁钢围堰的拼装方法、起吊下放方式、以及吸泥下沉、纠偏、精定位等施工工艺及施工关键技术,提出了深水承台双壁钢围堰施工中应注意的相关问题。     

统计方法在沥青路面施工管理中的应用

文章介绍了统计方法在沥青路面施工质量动态管理中的应用,提出了用平均值-标准差控制图、平均值-极差控制图,对沥青路面施工过程中的检测数据进行动态分析,及时检查出施工中的变异性环节,使沥青路面的施工质量处于较为理想的受控状态。     

基于有限元的金属波纹管柱失稳分析和试验研究

金属波纹管的稳定性在宇航、航空、精密仪表以及大型工程结构等领域属于关键技术指标,而且是研究难点。为了解决这类问题,文中应用MSC.Marc软件,针对典型的U型波纹管进行柱失稳研究,研究其极限失稳压力以及变形规律等。通过试验验证,有限元法的分析精度优于工程方法。将有限元法、工程设计和试验结合应用,共同进行金属波纹管柱失稳研究,能够显著提高设计精度,加快研制进程,减少研制成本,进而提高产品的综合性能与市场竞争力。     

Finding the most reliable path with and without link travel time correlation: A Lagrangian substitution based approach

Path travel time reliability is an essential measure of the quality of service for transportation systems and an important attribute in travelers’ route and departure time scheduling. This paper investigates a fundamental problem of finding the most reliable path under different spatial correlation assumptions, where the path travel time variability is represented by its standard deviation. To handle the non-linear and non-additive cost functions introduced by the quadratic forms of the standard deviation term, a Lagrangian substitution approach is adopted to estimate the lower bound of the most reliable path solution through solving a sequence of standard shortest path problems. A subgradient algorithm is used to iteratively improve the solution quality by reducing the optimality gap. To characterize the link travel time correlation structure associated with the end-to-end trip time reliability measure, this research develops a sampling-based method to dynamically construct a proxy objective function in terms of travel time observations from multiple days. The proposed algorithms are evaluated under a large-scale Bay Area, California network with real-world measurements.