变速移动荷载作用下刚性路面的动力响应研究

分析了行驶车辆加速、减速及飞机起降过程中变速移动荷载所引起的刚性路面的动力响应。结果表明,荷载的行进速度对刚性路面动态挠度的最大值有很大影响,而加速度主要影响挠度最大值出现的位置。     

基于LS-SVM船舶动力定位有限时间控制器设计

为了解决船舶模型存在任意不确定性的船舶动力定位问题,基于有限时间Lyapunov理论提出了一种非奇异快速终端滑模控制策略,提高了系统收敛速度及抗干扰能力。针对模型不确定性问题,利用最小二乘支持向量机(LS-SVM)的非线性函数逼近技术进行补偿控制,引入“最小参数”技术,将在线学习参数减少到一个,解决了“维数灾难”问题。最后的仿真对比结果验证了提出的控制策略的优越性。     

西安至宝鸡客运专线引入宝鸡枢纽方案研究

宝鸡枢纽衔接陇海、宝成、宝中3条铁路干线,西宝客运专线拟建车站位于渭河南侧城市新区,结合既有宝鸡枢纽功能和现状论述客运专线引入枢纽方案,从近远期工程的差异性、线路技术条件、与城市规划的协调、工程投资4个方面进行分析比较,确定新建南环客运专线及新宝鸡客站为西宝客运专线引入枢纽推荐方案。     

Which terminals should expand investment: a perspective of internal non-cooperative competition in a port?

ABSTRACT

With the increasing container cargo throughput and the arising of port congestion, container ports start to choose the investment expansion strategy to increase the port efficiency and then to figure out the problem of port congestion. To analyze this strategy, we formulate a non-cooperative game model for a two-terminals-one-port system, and derive the optimal equilibrium outcomes of the investment expansion strategy and investment constant strategy. In the game, we find that when the investment parameter of expansion strategy and impact of handling efficiency on demand changes, both pure-strategy Nash equilibrium and mixed-strategy Nash equilibrium exist, and two terminals are more likely to choose the investment expansion strategy in most cases. Numerical simulation is applied to explore the equilibrium strategy under different circumstance.     

速效胃宁片的抗胃溃疡作用

对速效胃宁片进行了大白鼠、小白鼠三种溃疡模型的药效学研究。结果表明此药对三种胃溃疡模型（幽门结扎型、慢性乙酸型、利血平型）具有预防、保护和促进愈合作用；能明显降低大鼠胃液分泌和抑制胃蛋白酶活性；定量给药能增加小鼠体重。     

Terminal investment timing decisions in a competitive setting with uncertainty using a real option approach

This paper uses a real option approach to analyze terminal investment timing decisions for situations in which a port faces competition from its rivals in an uncertain market. We propose a network model to describe carriers’ cargo routing decisions and competition among rival ports. We then transform this model into a multicommodity flow problem and use the column generation algorithm to solve it. After obtaining a port’s possible future annual revenues and the potential net present value (NPV) for its terminal construction project through the network model, we adopt the expanded NPV rule and transform the investment timing decision into an optimal stopping problem. A least squares Monte Carlo simulation algorithm is proposed to find the investing probabilities for future years. The proposed models are applied to a steel cargo terminal investment case in the Port of Bengbu in Anhui province of China. The impacts on the investing probability and the expanded NPV of changes in the demand volatility, the initial investment and the port discharging rate are analyzed to provide managerial insights for port managers.     

An updated fast continuous contact detection algorithm and its implementation in case study of ice-structure interaction by peridynamics

Peridynamics is a mesh-free particle method that has been proposed in the last two decades. Contact between bodies in Peridynamics is a challenging and critical phenomenon that not only affects the computational efficiency of the algorithm, but is also closely related to the accuracy of the calculations. Therefore, it is important to develop a contact detection algorithm that is efficient, accurate, easy to extend to coupled numerical methods, and conducive to parallel computation. This study proposes a fast and continuous contact detection algorithm (FCCDA) that consists of two main parts. The first involves establishing a regular box bounding the entire target of collision to avoid the unnecessary calculation of material points that are not in contact with it, where this critically reduces the number of time-consuming calculations. The second part is a graphics-based algorithm to identify specific particles that penetrate the target. Both the numerical strategies and the mathematical methodologies of the FCCDA are discussed here. It was embedded into a Peridynamics system and examined in the context of a benchmark case for verification. Ship–ice interaction and propeller–ice interaction are also demonstrated using the proposed algorithm as examples of its applications to engineering.     

基于DEA法的大城市快速路网综合评价研究

文章从定量和定性两个角度,建立了快速路网运行效率的综合评价指标体系,并利用DEA方法建立快速路网综合评价模型,通过实例对城市快速路网的运行效率进行有效性评价分析。结果表明,该方法具有较强的可操作性和实用性。     

基于型面模板的覆盖件拉延模型面快速设计研究

基于型面模板概念，针对构成型面模板工艺要素之间的相互关系建立了型面模板的装配关系模型，研究了型面模板参数化造型系统的实现技术?介绍了基于型面模板的覆盖件拉延模型面快速设计过程。从冲压方向的确定、边界识别和关键点的创建、压料面的设计、工艺补允面的没计及拉延筋设计等方面，对所开发的汽车覆盖件拉延模型面设计系统进行了介绍。     

FFT算法截断不确定度评估

截断不确定度是快速傅里叶算法(Fast Fourier Transform,FFT)不确定度评估中的一个重要来源。将截断不确定度分解为：频谱泄露不确定度、加窗和栅栏效应不确定度进行分析。将采样周期个数分解为整部部分和小数部分,确定小数部分引起的频谱泄露误差区间,以此为基础给出频谱泄露不确定度的评估方法;将加窗和栅栏效应引入的不确定度作为一个整体分析, 避开分量之间的相关性,以三角窗为例给出了一个通用的评估方法。之后利用GUM(Guide to the Expression of Uncertainty in Measurement)中的B类方法对其进行评定,评定时假设舍入测量不确定度为反正弦分布,并通过对频谱泄露不确定度、加窗和栅栏效应不确定度进行合成,得到最终的截断不确定度,在此基础上建立了FFT截断不确定度的通用评估方法。