Evaluation of energy consumption of vehicles in EU Trans-European Transport Network

The paper presents the results of field tests evaluating energy consumption in the vehicles of Trans-European Transport Network (TEN-T) of selected EU countries: Poland, Germany and France. The energy consumption of vehicles in a highway system was assessed based on the telemetry analysis systems for traction parameters, tachograph record of digital speed waveform and their statistical analysis. The empirical cumulative distribution functions of speed transitions (acceleration, deceleration) were used to determine the kinetic energy losses of the vehicle (fuel consumption). To assess the statistical significance of differences between cumulative distribution functions the Smirnov–Kolmogorov test was used.     

基于细长体公式的Truss SPAR在波流中的运动响应预报方法

利用细长体公式和刚体非线性运动方程建立Truss SPAR在波浪与流中运动响应预报方法。通过波浪自由表面和SPAR中心线方程构造辅助函数,迭代计算Truss SPAR瞬时湿长度。根据SPAR主体形状特点和流场中水质点运动规律,分段高效积分Truss SPAR上的水动力载荷。通过Runge-Kutta-Fehlberg方法求解运动方程,得Truss SPAR在波浪与流中的运动响应。对一座Truss SPAR在不同波流工况中的运动响应进行了预报,结果显示波浪和流使Truss SPAR产生了明显漂移运动和振荡运动,漂移运动的大小与流的方向有关,而振荡运动的幅值与波浪的方向有关。     

Ship resistance when operating in floating ice floes: Derivation,validation, and application of an empirical equation

With the effects of global warming, the Arctic is presenting a new environment where numerous ice floes are floating on the open sea surface. Whilst this has improved Arctic shipping navigability in an unprecedented way, the interaction of such floes with ships is yet to be understood to aid the designing of ships and route planning for this region. To further explore this topic, the present work develops a procedure to derive an empirical equation that can predict the effects of such floes on ship resistance. Based on a validated computational approach, extensive data are extracted from simulations of three different ships with varying operational and environmental conditions. The ice-floe resistance is shown to strongly correlate with ship beam, ship buttock angle, ship waterline angle, ship speed, ice concentration, ice thickness and floe diameter, and the regression powers of each of the parameters on resistance are ascertained. This leads to a generic empirical equation that can swiftly predict ice-floe resistance for a given ship in a given condition. Subsequently, demonstrations are given on the incorporation of the derived equation into a set of real-time Arctic ship performance model and voyage planning tool, which can predict a ship's fuel consumption in ice-infested seas and dynamically suggest a route with the least safety concern and fuel consumption. Moreover, the equation is validated by providing ice resistance prediction for experimental and full-scale conditions from multiple sources, showing high accuracy. In conclusion, the empirical equation is shown to give valid and rapid estimates for ice-floe resistance, providing valuable insights into ship designs for the region, as well as facilitating practical applications for polar navigation.     

Prediction of slamming pressure considering fluid-structure interaction. Part II: Derivation of empirical formulations

This is Part II in a series of papers. Part I [1] investigated the slamming responses of flexible flat stiffened steel and aluminum plates using the nonlinear explicit finite element code LS-Dyna with the Multi-Material Arbitrary Lagrangian-Eulerian (MMALE) solver. Subsequently, a simplified finite element FSI model of water hitting structures that is realistically close to the slamming phenomenon occurring on the bottom part of offshore structures was proposed. The proposed FSI methodology presented in Part I was verified by comparison with the relevant test data. It was evident that the use of the proposed numerical method presented in Part I was very effective for a benchmarking investigation of slamming load considering the hydroelastic effect. However, the method required much effort in terms of computation time and power analysis resources. The present study, Part II, aimed, as an alternative to the FSI analysis approach, to develop empirical formulae for prediction of slamming loads acting on deformable flat stiffened plates used in marine applications. This paper begins by describing the limitations of the existing approaches based on theoretical, experimental and even numerical studies conducted in the past for estimation of slamming loads. Next, it presents, based on the simulation methodology developed in Part I, rigorous parametric studies that had been performed on actual scantlings of marine-seagoing structures. The effects of structural geometry and water impact velocity on slamming pressure are then investigated in detail. Subsequently, the parametric results are analyzed and utilized to derive empirical formulations for the prediction of slamming loads acting on flat stiffened plates of marine structures. The accuracy and reliability of the proposed formulations are established by comparison with the results of the test and other existing formulations. The proposed formulations are expected to be used for the purposes of the design without any time-consuming FSI analysis of advanced and optimal structures that are robust to slamming.     

Collecting ambient vehicle trajectories from an instrumented probe vehicle: High quality data for microscopic traffic flow studies

This paper presents the methodology and results from a study to extract empirical microscopic vehicular interactions from a probe vehicle instrumented with sensors to monitor the ambient vehicles as it traverses a 28 mi long freeway corridor. The contributions of this paper are two fold: first, the general method and approach to seek a cost-effective balance between automation and manual data reduction that transcends the specific application. Second, the resulting empirical data set is intended to help advance traffic flow theory in general and car following models in particular. Generally the collection of empirical microscopic vehicle interaction data is either too computationally intensive or labor intensive. Historically automatic data extraction does not provide the precision necessary to advance traffic flow theory, while the labor demands of manual data extraction have limited past efforts to small scales. Key to the present study is striking the right balance between automatic and manual processing. Recognizing that any empirical microscopic data for traffic flow theory has to be manually validated anyway, the present study uses a “pretty good” automated processing algorithm followed by detailed manual cleanup using an efficient user interface to rapidly process the data. The study spans roughly two hours of data collected on a freeway during the afternoon peak of a typical weekday that includes recurring congestion. The corresponding data are being made available to the research community to help advance traffic flow theory in general and car following models in particular.     

轿车空调车室内温度场分布特性的经验公式

针对轿车空调车室内的温度场分布特性，在理论分析并结合实验测量和数值模拟的基础上，提出简捷而较可靠的动态经验公式。该经验公式考虑环境温度，太阳辐射，空调送风参数和人体等诸多影响因素后，可以计算在任意时刻下的轿车空调车室内的任意空间点处的温度值。     

Deconstructing delay: A non-parametric approach to analyzing delay changes in single server queuing systems

This paper introduces an empirically driven, non-parametric method to isolate and estimate the effects that changes in demand and changes in throughput have on delay – in particular, arrival and departure flight delay at airport runways. Classic queuing concepts were used to develop a method by which an intermediate, or counterfactual, queuing scenario could be constructed, to isolate the delay effects due to shifts in demand and throughput. This method includes the development of a stochastic throughput function that is based entirely on data and has three key features. Firstly, the function relies on non-parametric, empirically-based probability distributions of throughput counts. Secondly, facility capacity needs not be explicitly defined, as it is implicitly included in the probability distributions of throughput. Thirdly, the throughput performance function preserves the effect of factors that cause capacity (and, therefore, throughput) to fluctuate over a given period. Temporal sequences of high, moderate, and low capacity are maintained between the observed and counterfactual scenarios. The method was applied to a case study of the three major New York area airports of LaGuardia (LGA), Newark Liberty (EWR), and John F. Kennedy (JFK), using operational data extracted from the Federal Aviation Administration’s (FAA’s) Aviation System Performance Metrics (ASPM) database. The focus was on the peak summer travel seasons of 2006 and 2007, as these airports experienced record levels of delay in 2007. The results indicate that decreases in both demand and throughput were experienced at LGA and EWR, although the decreases in throughput had more significant effects on operational delays as they increased overall at these airports. At JFK, the increase in departure throughput was not sufficient to offset the increase in departure demands. For arrivals, demand increased and throughput decreased. These trends caused a significant growth in delay at JFK between 2006 and 2007.     

城市轨道交通线网规模匡算研究

针对传统轨道交通线网匡算模型指标取值难度大、主观性强、灵敏度差的缺点,从可量化角度,以减少指标参数主观取值为目标,首先在远景城市全方式出行距离与全方式出行量之间分段方程的基础上,运用Logit模型,构建了理想交通结构测算模型,其次在规模经济与规模不经济的理论基础上,构建基于收支平衡点的理想负荷强度平衡方程,最后通过构建的综合模型对成都市远景轨道交通线网规模进行匡算实证分析。测算结果表明:该模型的测算灵敏度明显优于线网服务覆盖面法且能有效避免传统算法中因指标取值不当带来误差放大的影响。     

层状结构受电弓滑板材料配方的试验研究

为确定层状结构受电弓滑板基体的最佳物料配比,采用均匀设计法设计配方试验方案,并根据试验结果回归分析碳纤维、石墨、硅灰石纤维、铜粉和铜纤维的比例对受电弓滑板性能的影响。结果表明:当碳纤维、石墨、硅灰石、铜粉和铜纤维的质量百分比分别为16%,11.2%,11.2%,2.4%和8%时,受电弓滑板具有较好的综合性能,且符合TB/T 1842.2—2002标准,其电阻率和冲击强度分别为6.28μΩ.m和16.04 kJ.m-2,比标准规定的限值分别降低了47%和提高了541%。     

标准贯入试验在中泰铁路中的应用与研究

中泰铁路作为国外重点项目,具有地质勘察时间紧、任务重、成本高的特点。标准贯入试验(SPT)作为一种操作简单,指标可靠易用的方法可有效解决上述问题。如何将国外操作工艺所获得的指标合理地运用到我国设计理念中,显得极为重要。从SPT的原理入手,通过对有国内成熟经验地区的SPT数据与地层主要物理力学指标的对比分析,而后结合该项目国内外的SPT对比试验数据进行数据拟合,得出SPT与常用物理力学指标之间的经验公式并将其应用于设计中。同时发现随着深度的增加,N_泰相对N_中来说数据偏大的现象愈加明显,并从钻探方法及SPT方法两个方面进行综合分析,最终得出SPT方法的优越性及日后应用中的注意事项和进一步的研究方向。