Simplified analysis for estimation of the behavior of a submerged floating tunnel in waves and experimental verification

To achieve rational design in waves for a submerged floating tunnel which has emerged as a new offshore transportation infrastructure, it's necessary to understand its hydrodynamic behavior. For simple but accurate estimation of hydrodynamic forces, a theoretical method is proposed and the tests with physical models in a wave flume were carried out for verification. Morison's equation was used to estimate wave loads composed of inertia force and drag force. Forces calculated by applying the linear wave theory to Morison's equation coincided well with those measured by the tests. The test results showed that mooring systems played a significant role in the movement of the submerged floating tunnel in waves. A pendulum model could be used to describe the motion of the submerged floating tunnel with a single vertical mooring. Based on the verified relations, a simple slack condition which causes the submerged floating tunnel to be unstable was also proposed. The simplified approach proposed by this study proved to be useful in designing the submerged floating tunnel in the initial stage.     

对铁路站场到发线曲线地段建筑限界加宽方法的探讨

现行规范对铁路站场到发线曲线地段建筑限界加宽方法有相关规定,实际应用中因动车组列车与普速列车基本参数的差异导致曲线地段建筑限界加宽与实际有差距。通过阐述铁路站场设计现行曲线限界加宽的相关规范规定,结合铁路总公司对客站曲线地段建筑限界加宽的最新要求,分析铁路到发线曲线地段建筑限界加宽的理论计算公式,指出现行曲线地段建筑限界加宽规定存在的主要问题,从而修正现行曲线地段建筑限界加宽的相关规定,以满足实际曲线地段建筑限界加宽要求,杜绝运营中发生车体剐蹭建筑物的事故。     

Review and Outlook of Roundabout Capacity

Capacity is an important part of the operation efficiency at roundabouts. Through analyzing existing capacity models of roundabout, this paper focuses on the problem research principles and methods such as empirical regression model, gap acceptance model and model based on simulation software. The key technologies of modeling are also analyzed. Then the general approaches of modeling roundabout capacity are proposed, combined with some problems easily overlooked in previous study. Determining the interaction mechanism among each traffic flow and considering the significant impact factors, the capacity model is established on the whole. Finally, combing with the control objectives of roundabouts, an outlook is proposed for future studies on roundabout capacity.     

关联理论视角下的语篇连贯研究

以Sperber＆amp;Wilson提出的关联理论为研究视角，通过对关联理论提出的关联原则、认知语境观、明示－推理交际观等主要观点的分析和理解，结合具体的例句，进一步探索该理论对命题内容连贯和语境效果连贯两大语篇连贯类型的解释力，并得出结论：正确判断某个语篇是否连贯不在于形式上的衔接，主要体现在“言而有其义”，语义上的关联才是贯穿整个语篇的主线。     

Brake light cellular automaton model with advanced randomization for traffic breakdown

Traffic breakdown is one of the most important empirical phenomena in traffic flow theory. Unfortunately, it cannot be simulated by many traffic flow models. In order to clarify its mechanism, the new brake light cellular automaton model has been proposed. Comparing with previous brake light models, three different aspects have been considered: (i) drivers tend to take large decelerations if the time gap is smaller than the safe time gap and the leading vehicle’s brake light is on; (ii) the brake light rule is set according to the reality; (iii) the randomization rule is put forward before the acceleration rule to weaken the impact of brake light on driving behaviors. Analyses show that the new model can explain the mechanism of traffic breakdown and the failures of other brake light models. Simulations confirm that all empirical features of traffic breakdown are successfully reproduced. At last, brake light models are calibrated and validated by the I-80 empirical data provided by NGSIM. Results show that the performance of the new model is the best and models in the three-phase theory are not necessarily better than models in the fundamental diagram approach and vice versa, at least for the brake light models.     

考虑车道荷载差异的多车道桥梁横向折减系数

为考虑车道荷载差异对多车道桥梁横向折减系数的影响，提出横向折减系数的多系数表达模式，并改进基于独立重复试验的相遇车道荷载方法以进行系数校核。首先，引入反映车道荷载差异性的车道修正系数和体现多车道荷载相遇概率的车道组合系数，形成横向折减系数的多系数表达模式。其次，改进目前常用的基于独立重复试验的相遇车道荷载方法，将车道交通流量及荷载分布的差异性涵盖进来。随后，参数化研究横向折减系数的关键影响参量，包括货车通过控制断面的平均时间、荷载重现期、车道交通量和车道荷载分布等。最后，基于某高速公路实测动态称重数据，给出采用该方法校核横向折减系数的详细过程，并与传统方法及JTG D60-2015规范方法所得结果进行对比。研究表明：所提出的改进相遇车道荷载方法，摈弃了传统方法中车重正态分布、车道荷载同分布、最大观测车重与均值3.5倍偏差关系等备受质疑的假设，是更一般性的解答。参数化分析表明：货车通过控制断面的平均时间和荷载重现期对结果影响很小，货车荷载模型及其在车道间差异性则影响很显著，说明对车道荷载分布规律进行准确建模的重要性。实测车道货车荷载数据统计发现：货车的交通量和荷载分布在车道之间具有明显的差异，传统方法和规范方法给出的横向折减系数均高估了实际情况，最大达19%，可能造成设计与管养资源的浪费；而基于该方法校核的横向折减系数，更能深入揭示各车道荷载的贡献规律，准确反映不同车道组合作用下的荷载横向折减规律，具有显著的工程应用价值。     

U型车箱载荷计算方法的应用研究

为了寻求一种较为科学的U型车箱面板载荷计算方法,先采用多种土压力理论对车箱各面板进行载荷的计算,而后利用载荷计算结果在A NSYS下对U型车箱进行应力分析并与试验结果进行对比,最后通过分析,找到一种较为合理的U型车箱面板的计算方法。     

半潜式钻井支持平台在不规则波中的时域耦合分析

基于三维势流理论和莫里森方程,运用水动力软件AQWA,计算半潜式钻井支持平台的水动力特性。同时运用时域耦合方法,计算了风、浪、流共同作用下,半潜式钻井支持平台在三种工况(迎浪、斜浪和横浪)下的运动响应及系泊系统动力响应。时域耦合分析结果验证了该钻井支持平台满足规范要求。     

基于AHP的指挥控制系统效能评估改进方法

针对指挥控制系统的组成结构特点,建立效能评估指标模型,给出运用层次分析法进行效能评估的数学模型及实现方法,引入灰色理论解决评估过程中指标权重的调优问题,提高评估结果的客观性及合理性,通过实例说明方法的可行性。     

面元法中偶极子影响系数计算分析*

分析了不同方法应用于偶极子影响系数的计算,并详细介绍了Gauss‐Bonnet定理在偶极子影响系数计算中的应用。探讨了这些计算方法的近似处理及由此造成的误差,进而以Gauss‐Bonnet定理为基础提出了计算偶极子影响系数的修改办法。将此种修改办法应用于面元法的计算中,以×××桨及×××桨为计算对象,分析修改前后的偶极子计算方法对计算结果精度的影响。从理论上探讨了面元法中,有关偶极子影响系数计算环节的误差及减小此部分误差的办法。