基桩荷载传递的非线性计算方法研究

大量试桩资料表明,桩身荷载传递函数曲线多符合双曲线模型,故有必要对基桩荷载传递性状进行非线性分析。为此,文章首先讨论了桩侧摩阻力的主要影响因素和计算方法,然后引入双曲线模型,以荷载传递法建立桩身荷载传递基本微分方程。在此基础上,导得了考虑桩土相互作用及土体分层性质的幂级数解答,并将其用于实测试桩资料的数据分析。对比分析结果表明,基于双曲线模型的非线性计算方法能更准确的描述桩身荷载传递性状,且参数易于获取,是一种可行的计算方法。     

On altruists and egoists in activity participation and travel: who are they and do they live together?

Formulation and specification of activity analysis models require better understanding of time allocation behavior that goes beyond the more recent within household analyses to understand selfish and altruistic behavior and how this relates to travel behavior. Using data from 1,471 persons in a recent 2-day time use/activity diary and latent class cluster analysis we identify 11 distinct daily behaviors that span from the intensely self-serving to intensely altruistic. Predicted cluster membership is then used to study within household interactions. The analysis shows strong correlation exists between social role and patterns of altruistic behavior. However, a substantial amount of heterogeneity is also found within social roles. In addition, travel behavior is also very different among altruistic and self-serving time allocation groups. At the household level, a substantial number of households contain persons with similar behavior. Another group of households contains a mix of self-serving and altruistic persons that follow specialized household roles within their households. The majority of households, however, are populated by altruistic persons. Single person households are more likely to be in the self-serving groups but not in their entirety. Altruism at home is directed most often toward the immediate family members. This is less pronounced when we examine altruistic acts outside the home. Konstadinos G. Goulias is a professor of Geography at the University of California Santa Barbara, has been a professor of Civil Engineering at the Pennsylvania State University from 1991 to 2004, and he is the founder and chair of the TRB task force on moving activity-based approaches to practice. Kriste M. Henson is a technical staff member at Los Alamos National Laboratory in the Decision Applications Division and is currently pursing a Ph.D. in Geography at the University of California—Santa Barbara.     

SH波激励下上覆粘弹性场地土的振动分析

采用工程波动理论,考虑简谐SH波诱发的水平振动和场地土的材料阻尼,假定场地土体系处于反平面应变状态,研究半空间上SH波激励下上覆粘弹性场地土的自由场动力反应。利用正交函数法求解基岩运动输入下上覆土层的振动解,以此解来分析SH波激励下粘弹性场地土的放大效应,并将探讨其影响因素。本文结果为进一步研究土—结构物动力相互作用打下坚实的基础,对建筑抗震设计和震害分析具有理论和工程实际意义。     

嵌入式信息无线交互城市公交报站控制系统的设计与实现

嵌入式信息无线交互城市公交报站控制系统涉及无线信息编、解码通讯，数据融合与信息处理，单片机嵌入式控制，语音生成与处理，车载电源变换等技术支持。实现车辆上、下行运程相关信息的人性化报读，站点与车载装置无线信息交互。     

“桥头跳车”对连续梁桥动力响应的影响分析

“桥头跳车”是由路基与桥台连续处的高差而引起的车辆跳跃现象。本文参照简化的车辆模型和桥梁模型建立了车—桥相互作用的数学模型,提出了一种车—桥振动简化计算方法。利用该方法考虑“桥头跳车”对连续梁桥各特征截面动力响应的影响,通过数值分析可定性地确定“桥头跳车”现象对汽车荷载冲击系数取值的影响,为将来冲击系数的进一步修改提供参考。     

OSCAR statement of methods

OSCAR (Outil de Simulation du CAptage pour la Reconnaissance des défauts) is the pantograph–catenary dynamic software developed by Société Nationale des Chemins de fer Français (SNCF) since 2004. A three-dimensional finite element (FE) mesh allows the modelling of any catenary type: alternating current (AC) or direct current (DC) designs, and conventional or high-speed lines. It is a representative of the real overhead line geometry, with contact wire (CW) irregularities, staggered alignment of the CW, dropper spacing, wire tension, etc. Nonlinearities, such as slackening of droppers and unilateral contact between the pantograph and the CW, are taken into account. Several pantograph models can be used, with a complexity level growing from the three-lumped-mass model to the multibody model. In the second case, a cosimulation between the FE method catenary and the multibody pantograph models has been developed. Industrial features for pre- and post-treatments were developed to increase robustness of results and optimise computation time. Recent developments include volume meshing of the CW for stress computation or statistical analysis and lead to new fields of studies such as fatigue failure or design optimisation. OSCAR was fully validated against in-line measurements for its different AC and DC catenary models as well as its different pantograph models (with independent strips for instance) and has continuously been certified against EN50318 since 2008.     

Simplified and advanced modelling of traction control systems of heavy-haul locomotives

Improving tractive effort is a very complex task in locomotive design. It requires the development of not only mechanical systems but also power systems, traction machines and traction algorithms. At the initial design stage, traction algorithms can be verified by means of a simulation approach. A simple single wheelset simulation approach is not sufficient because all locomotive dynamics are not fully taken into consideration. Given that many traction control strategies exist, the best solution is to use more advanced approaches for such studies. This paper describes the modelling of a locomotive with a bogie traction control strategy based on a co-simulation approach in order to deliver more accurate results. The simplified and advanced modelling approaches of a locomotive electric power system are compared in this paper in order to answer a fundamental question. What level of modelling complexity is necessary for the investigation of the dynamic behaviours of a heavy-haul locomotive running under traction? The simulation results obtained provide some recommendations on simulation processes and the further implementation of advanced and simplified modelling approaches.     

车路协同系统的视景仿真模型

在车路协同系统仿真的基础上,以局部交通网络的实时交通仿真为例,建立了车路协同系统视景仿真模型库,确立了视景仿真系统的框架体系结构。将视景仿真集成为整个仿真系统的一个联邦成员,建立了车车信息交互、车路信息交互的典型视景仿真功能模型。使用LOD模型简化技术对视景仿真功能模型进行分解,生成了5个不同精细程度的LOD模型。采用DOF、LOD、Switch功能化节点,从节点结构上优化了典型应用场景中的交叉口信号灯、车辆运动等相关模型,建立了一套类似模型几何形状的层级节点结构。构建了车路协同系统可视化视景仿真平台,包括HLA/RTI信息交互与控制模块、车路协同数据处理模块、信息交互模块、模型引导控制模块、视角动态切换模块与模型状态参数动态显示模块。采用建模优化相关技术,对典型交通场景进行了视景仿真。仿真结果表明:通过LOD模型简化技术,模型简化率最高可达95.5%,内存占用减少86.3%;通过视景仿真方法的使用,提高了渲染效率与系统仿真效率,车路协同典型交通场景验证了仿真方法的可行性。     

浅水条件下船舶通过船闸时的水动力性能数值研究

文章通过应用CFD方法数值模拟在浅水条件下通过船闸的船舶粘性绕流,对船舶通过船闸时的水动力性能进行了数值预报研究。通过UDF编程定义船舶的运动,使用动网格方法和滑移交界面技术进行船舶运动过程中的网格更新,计算作用在船体上的水动力,并由计算得到的水动力求得船体下沉和纵倾。为了验证所采用的数值方法,以一艘通过比利时泽布吕赫Pierre Vandamme船闸的船舶为例,在模型尺度下进行了计算,并将计算结果和佛兰德水利研究所的模型试验基准数据进行了比较。通过分析不同船速、偏心距和水深条件下的数值结果,给出了这些因素对船舶通过船闸时的水动力性能的影响。该文研究结果可为浅水条件下船舶通过船闸时的安全操纵和控制提供一定的指导。     

基于ALE的矿粉货物液化晃荡问题并行数值模拟

含水量较高的矿粉货物在海上运输过程中易出现液化,形成自由表面并使晃荡现象加剧,严重威胁船舶运输安全。针对船载液化矿粉晃动和舱壁冲击问题,采用ALE有限元方法对其进行了细致建模和计算模拟,从三维角度考察了在船舱一定装载率和运动状态下液化矿粉的晃荡现象和特性;同时,借助不同仿真软件,对计算结果的合理性和准确性进行了相互比对和分析。模型求解借助了高性能计算资源,以解决问题求解时间长和多组计算工况带来的大规模计算需求;结合所建计算模型特点和流固耦合特性,研究了多核环境下两种不同区域分解策略和实现方式,通过并行计算性能数据比较分析,以探求更为合理的并行加速策略。