弹性接触问题的位移-力法有限元解法研究

本文根据接触状态下的有限元基本方程,通过对定解条件、约束条件的分析应用,得出了仅与接触点有关的定解方程。 运用所编制的电算程序对某柴油机副连杆销及孔在最大载荷下的失圆变形进行了计算。通过采用空心及实心销两种简化模型计算得出了实际副连杆销的失圆变形范围。     

温度和麻醉对神经几种兴奋性指标的影响——兼论何者可以正确反映兴奋性

在蟾蜍坐骨神经-腓神经观察了温度和麻醉对几种兴奋性指标的影响。结果表明,标准电量(a)随兴奋性的变化而有规律地变化。兴奋性愈高。a值愈小。而Weiss式中的b、基强度(Rh)、时值(Chr)及强度—时间曲线均不能正确反映兴奋性。细胞膜时间常数(RC)与兴奋性的变化无规律性联系。结论,a是兴奋性的可靠定量指标。     

新型无线感应技术在模拟载波通信中的应用

与传统的感应无线技术相比,新型无线感应技术具有更好的抗干扰能力且减少了一根传输线,应用于机车,特别是磁浮列车的自动驾驶中,可以满足列车自动化驾驶中通信定位测速的需求。为此对新型无线感应技术在模拟通信中的应用进行分析。以单频模拟信号为调制信号,对连续正(余)弦载波进行调幅、调相和调频等调制,得到AM,DSB,SSB,窄带调频,窄带调相等已调信号通过新型无线感应系统时的不同解调新方法,并对新型无线感应系统的AM,DSB,SSB,窄带调频,窄带调相等调制解调进行仿真。结果表明:新型无线感应技术可以应用于模拟载波通信中恢复原始信号。     

Evaluation of expected maximum values of forces acting on containers and lashing rods on a container ship

The appearance of a number of large container ships in the 8000 TEU range raises the importance of a plan for container lashing arrangements on deck in relation to the design of the ship. Therefore, it is expected that a new method for evaluating the lashing arrangements on deck will be introduced which is applicable regardless of the ship's size and the lashing pattern, instead of using the standards of several different societies, as happens at present. To evaluate the lashing arrangements on deck, the expected maximum values of the forces acting on the containers and lashing rods should be evaluated. This paper presents a new method of evaluating the container lashing arrangements on a container ship using an "acceleration ellipsoid." The applicability of the acceleration ellipsoid to an evaluation of the expected maximum values of the forces was examined by comparing the expected maximum values of the forces calculated by the long-term distribution calculation known as the "Fukuda method," to those calculated using the acceleration ellipsoid. By comparing these results, it was confirmed that the expected maximum values of the forces calculated using the acceleration ellipsoid were not less than those calculated through by the long-term distribution calculation. It is concluded that the acceleration ellipsoid can be used to evaluate the expected maximum values of the forces acting on containers and lashing rods. Received: December 14, 2000 / Accepted: March 22, 2001     

电气化公路技术研究

交通是能源消纳的重要领域，其对社会能源结构的调整和节能减排具有重要的影响和带动作用。在陆路交通方面，轨道交通和小型客运车辆的电气化发展方向相对清晰，而公路货运尚无明确的技术路线。为充分利用清洁能源，减少化石能源在交通领域中的使用，发展并推广电气化公路技术，对重载卡车的蓄电池、燃料电池、混合动力3种电气化方案进行对比分析，结合卡车负载的特点，对不同电气化方案进行评估。研究融合新能源发电及并网、混合动力技术、智能驾驶技术的电气化公路技术，从车辆动力技术、供电线路、受电弓与计费、新能源并网、编组智能驾驶运行5个方面对电气化公路方案进行介绍，可以实现公路货运系统的绿色、安全、高效运行。以10公里线路电气化为例，进行规划和成本估算，构建单车和区域（或路段）电气化的运营成本计算模型，基于燃油消耗和阻力分析2种方法进行计算。对车辆购置及改装、基础设施建设、可再生能源发电、系统环保效益等4个方面进行技术分析与成本测算。从供能技术变革、商业模式和推广路线3个角度对电气化公路技术的未来推广进行论证展望。研究结果表明：电气化公路技术的应用与规模化能够带来巨大的经济与环境收益，其中的混合动力方案与架空线输电方案为面对未来可能的储能技术变革与无线输电普及打下重要的基础，提供了拓展空间，也是重载货车实现智能驾驶的重要步骤；与燃油驱动相比，电驱动百公里成本减少96元，单一重卡年运营成本减少18.8万元，百公里污染物（如：碳氧化物、氮氧化物等）均减少50%以上。     

减摇鳍与舭龙骨组合体定常升力数值计算

运用涡格法（ＶＬＭ）建立了前后两对鳍与中间舭龙骨构成组合的定常升力的数值计算模型,其中考虑了梢涡和尾涡的分离与卷起、计算结果与文献［１］的试验结果吻合良好。     

船闸引航道异重流淤积分析计算

根据异重流运动的特点,从水体重率沿程变化的机理出发,运用能量原理,推导出异重流淤积计算公式,并用于大源渡船闸引航道淤积计算。所得成果与已有3种公式计算结果的平均值相当,通过类比分析,所得淤积量分布与实测资料一致。     

牵引定数不统一的港口后方腹地车流组织优化

线路区段牵引定数不统一是影响列车编组计划制定的重要因素,导致了列车在部分区段欠轴运行,在换重站或技术站进行补减轴作业.本文重点论述了减重方向列车编组方案的优化问题,提出了按充分条件将各种方案归类的方法,从而减少方案成本的对比次数,能快速获得最优的运送方案.在方案成本构成的分析过程中,充分考虑了各影响因素,将牵引机车费用看作与里程相关的可变成本,将欠轴列车浪费的机车和线路能力转化为惩罚费用,并考虑列车开行频率对方案费用的影响,最后从全网络的角度建立减重方向减轴列车编组优化模型.该模型既可获得合理的减重站,又能依据车流量关系选择优化的减轴编组方式,实例验证了模型的有效性.     

Multi-step prediction of experienced travel times using agent-based modeling

This paper develops an agent-based modeling approach to predict multi-step ahead experienced travel times using real-time and historical spatiotemporal traffic data. At the microscopic level, each agent represents an expert in a decision-making system. Each expert predicts the travel time for each time interval according to experiences from a historical dataset. A set of agent interactions is developed to preserve agents that correspond to traffic patterns similar to the real-time measurements and replace invalid agents or agents associated with negligible weights with new agents. Consequently, the aggregation of each agent’s recommendation (predicted travel time with associated weight) provides a macroscopic level of output, namely the predicted travel time distribution. Probe vehicle data from a 95-mile freeway stretch along I-64 and I-264 are used to test different predictors. The results show that the agent-based modeling approach produces the least prediction error compared to other state-of-the-practice and state-of-the-art methods (instantaneous travel time, historical average and k-nearest neighbor), and maintains less than a 9% prediction error for trip departures up to 60 min into the future for a two-hour trip. Moreover, the confidence boundaries of the predicted travel times demonstrate that the proposed approach also provides high accuracy in predicting travel time confidence intervals. Finally, the proposed approach does not require offline training thus making it easily transferable to other locations and the fast algorithm computation allows the proposed approach to be implemented in real-time applications in Traffic Management Centers.