Experimental Investigation of TARMAX Model for Modeling of Hydrodynamic Forces on Cylinder-like Structures

A new approach that models lift and drag hydrodynamic force signals operating over cylindrical structures was developed and validated. This approach is based on stochastic auto regressive moving average with exogenous (ARMAX) input and its time-varying form, TARMAX. Model structure selection and parameter estimation were discussed while considering the validation stage. In this paper, the cylindrical structure was considered as a dynamic system with an incoming water wave and resulting forces as the input a...     

西安市公交客运量的回归分析预测研究

公交客运量的预测研究是非常重要的工作,根据西安市公交运量的相关数据,应用多元回归方法对西安市公交客运量进行预测分析,来确定未来某一时段的客运量,为西安公交网络规划提供决策依据。     

平面信号控制交叉口行人过街的时间模型

平面信号控制交叉口行人过街时间是道路交通安全和交通信号设置的重要参数.通过对成都市6个无左转专用信号的平面信号控制交叉口的24条人行横道上行人过街时间的调查与分析,利用统计学得到平面信号控制交叉口行人过街平均时间模型、85%位时间模型和90%位时间模型,最后根据最小二乘法对所选的主要影响因素与各个多元线性回归模型进行相...     

Financial and environmental impacts of hypothetical Finnish dry port structure

One main theme of European Union’s in transport policy statements has been the increased role of railways in the reducing environmental impacts and costs of transport activity. One option to increase the modal share of rail transport is to utilize the dry port concept, particularly applicable to general cargo. At the Port of Gothenburg (Sweden) use of this concept in combination with rail transport has led to a reduction of CO₂ emissions, and lower transport energy costs. The main objective and motivation of this research work are to examine through analytical models, how this same dry port concept could be implemented in the Finnish transportation network, with estimates of the benefits being gained.The research method of this study is macro gravitational models of distribution. Main input data for the models are distances and population in the area. The approach aims to research, how relative transport costs behave by increasing the number of dry port distribution locations. For the actual computation work the authors apply linear integer programming. Based on the results, the authors argue that relative transport costs can decrease considerably by increasing the number of dry ports, up to the level of six locations. This is considerably less than what is the current situation in Sweden. The found solution also differs from Sweden as the fragmented Finnish seaport system enables using numerous seaports instead of one, which further decreases inland transportation distances and volumes considerably. At the same time forthcoming sulphur emission reduction regulation (for sea transports) might impact the transportation network structure by decreasing sea transport and the number of seaports used. This might lead to a further increase in land-based hinterland transport.     

Changing accessibility, dwelling price and the spatial distribution of socio-economic activities

In this paper we present an activities-location choice model with endogenous price which simulates, based on Expected Random Utility principle, the behaviour of several agents of the urban system (e.g. the workers distinguished by income, the firms by economic sector) to estimate the spatial distribution of socio-economic activities within the study area as well as the impact of differential changes in accessibility on the dwelling price. The study area for this research is the metropolitan area of Napoli (South Italy), for which we show the results of the model estimation and the results of a “backcasting” analysis.     

交通事件持续时间预测贝叶斯网方法研究

交通事件持续时间的预测是事件管理系统的重要组成部分,根据I-880实测数据集,利用逐步回归分析的方法确定事件持续时间的主要影响因素,分别建立了应用于事件持续时间预测的朴素贝叶斯(NB)模型、加树朴素贝叶斯(TAN)模型以及一般贝叶斯网(BN)模型,在分析数据特点的基础上确定了贝叶斯网的推理算法、参数学习以及结构学习方法.在不同数据缺失的程度和不同训练样本规模下,分别对三种模型的预测准确率进行了评价,结果表明贝叶斯网预测模型在数据缺失30%的情况下30min准确率高于80%.     

含水率对砖砌体抗剪强度的影响

通过含水率对砖砌体抗剪强度影响规律的试验,分别测出不同砖砌体试件整体含水率、砖的含水率和砂浆缝砂浆的含水率与抗剪强度之间的关系,得到砖砌体试件随浸泡时间含水率的变化规律,给出了考虑含水率的砖砌体抗剪强度计算公式.通过试验可以看出,含水率对砖砌体抗剪强度有着重要影响,有关规范中应予以考虑.     

河北北部山区通村公路土基回弹模量对路面设计的影响研究

通过对河北北部山区通村公路进行现场试验,由回归分析得到土基回弹模量与弯沉的关系式,并根据不同土基强度与不同标准轴载对路面厚度设计的影响,对土基强度进行分级,可作为路面设计的依据。     

Lights,camera, legal action! The effectiveness of red light cameras on collisions in Los Angeles

This study estimates the effect of red light cameras (henceforth cameras) on collisions under the Los Angeles Automated Photo Enforcement Program that ran from 2006 to 2011. To control for selection bias and unobservables, a data set is constructed such that intersections with cameras are compared to control groups of nearby intersections without cameras, matched on observable characteristics. To capture potential spillover effects of cameras, control groups at various distances from the intersections with cameras are considered. A Poisson panel data model with random coefficients is applied to these data and estimated using Bayesian methods. The program suffered from weaknesses in enforcement. The city’s courts did not uphold citations and this dampened the effect cameras had on drivers. These problems are accounted for in modeling. Controlling for these concerns, results indicate that the cameras decreased red light running related collisions, but increased right-angle and injury collisions, as well as collisions overall.     

Findings from subjective evaluations and driver ratings of vehicle dynamics: steering and handling

This paper investigates subjective assessments (SA) of vehicle handling and steering feel tests, both numerical and verbal, to understand drivers’ use of judgement scales, rating tendencies and spread. Two different test methods are compared: a short multi-vehicle first-impression test with predefined-driving vs the standard extensive single-vehicle free-driving tests, both offering very similar results but with the former saving substantial testing time. Rating repeatability is evaluated by means of a blind test. Key SA questions are identified by numerical subjective assessment autocorrelations and by generating word clouds from the most used terms in verbal assessments, with both methods leading to similar key parameters. The results exposed in this paper enable better understanding of SA, allowing improving the overall subjective testing and evaluation process, and improving the data collection and analysis process needed before identifying correlations between SA and objective metrics.