Mathematical model of steel lazy-wave riser abandonment and recovery in deepwater

To meet the increasing applications of the deepwater steel lazy-wave riser (SLWR), the riser abandonment and recovery (A&R) is a great challenge for SLWR installation and its mechanical analysis is necessary and significant. This paper is focused on the abandonment and recovery process which is of great importance to the installation feasibility and analysis. A comprehensive mechanical model based on the nonlinear large deformation beam theory for simulating the deepwater SLWR is proposed. And a simple and suitable model for analyzing the A&R cable is developed. The presented model with detailed boundary conditions is able to deal with three different A&R methods. Numerical analysis is conducted by the finite difference method to investigate the riser configurations and somev important mechanical parameters of the pipeline and cable which exert influences on the riser's performance and the A&R cable's requirement. Parametric comparison study is conducted to analyze the advantage of different method. The proposed model can help on development of deepwater SLWR A&R design and analysis.     

一种基于拓展支持向量机的无人船路径规划方法

为有效解决无人船实现智能航行面临的路径规划问题，提出一种基于拓展支持向量机（SVM）的路径规划方法。该方法在传统SVM路径规划方法的基础上，考虑任务途中障碍物的规避风险，将工作任务的起止点作为约束条件对传统方法进行拓展，并针对不同的应用情景给出线性路径规划和非线性路径规划的求解方法。同时，为提高路径规划的效率，从SVM的原理出发，提出一种训练集裁剪的方法，大幅度减少利用SVM求解路径时所需的训练样本个数。此外，通过仿真验证该方法的可行性和有效性。     

基于弹塑性理论的隧洞围岩稳定可靠度分析

在隧洞围岩稳定性分析中,运用可靠度理论比传统的安全系数法更符合实际。以圆形隧洞围岩的弹塑性分析的解析解为基础,建立圆形隧洞围岩稳定性分析的可靠度分析模型。考虑到功能函数的高度非线性,采用Fortran语言编制可靠指标的计算程序,并结合实例对可靠指标的影响因素进行分析。     

Time control point strategy coupled with transfer coordination in bus schedule design

A schedule consisting of an appropriate arrival time at each time control point can ensure reliable transport services. This paper develops a novel time control point strategy coupled with transfer coordination for solving a multi‐objective schedule design problem to improve schedule adherence and reduce intermodal transfer disutility. The problem is formulated using a robust mixed‐integer nonlinear programming model. The mixed‐integer nonlinear programming model is equivalently transformed into a robust mixed‐integer linear programming model, which is then approximated by a deterministic mixed‐integer linear programming model through Monte Carlo simulation. Thus, the optimal scheduled arrival time at each time control point can be precisely obtained using cplex . Numerical experiments based on three bus lines and the mass rapid transit system in Singapore are presented, and the results show that the schedule determined using the developed model is able to provide not only reliable bus service but also a smooth transfer experience for passengers. Copyright © 2016 John Wiley & Sons, Ltd.     

On the existence of stationary states in general road networks

Our daily driving experience and empirical observations suggest that traffic patterns in a road network are relatively stationary during peak periods. In numerous transportation network studies, there has been an implicit conjecture that stationary states exist in a network when origin demands, route choice proportions, and destination supplies are constant. In this study, we first rigorously formulate the conjecture within the framework of a network kinematic wave theory with an invariant junction model. After defining stationary states, we derive a system of algebraic equations in 3-tuples of stationary link flow-rates, demands, and supplies. We then introduce a new definition of junction critical demand levels based on effective demands and supplies. With a map in critical demand levels, we show that its fixed points and, therefore, stationary states exist with the help of Brouwer’s fixed point theorem. For two simple road networks, we show that the map is well-defined and can be used to solve stationary states with a brute-force method. Finally we summarize the study and present some future extensions and applications.     

基于蚁群算法的维修保障资源应急调度研究

在保障资源损毁后,将现有保障资源整合成机动保障小组,按照一定的机动路线巡回实施支援保障,可以最大限度的节省现存保障资源,提高保障效能。实施机动巡回的资源调度,需要确定机动保障小组的数量以及机动的路线,这类问题可归结为带约束条件的组合优化问题。应用蚁群算法建立了机动巡回保障优化数学模型,给出了算法的实现步骤。案例结果表明,该算法可以快速、有效求得巡回保障的优化解,得到巡回保障过程中的较优方案。     

Statistical and machine learning approach for planning dial-a-ride systems

Door-to-door transportation service for elderly and persons with disabilities is often called dial-a-ride (DAR), and is usually provided by transit agencies through private contractors. Growth in DAR ridership is reported across the United States and this tendency will likely continue due to aging population. Such trends encourage development of models that can provide decision support in planning new DAR systems or expanding existing ones. Several statistical models were previously developed to predict the required DAR system capacity, given various characteristics of the service region, level-of-service requirements and operator constraints. Our work contributes to this line of research by proposing statistical and machine learning approaches that provide more accurate predictions over a wider range of scenarios. This is accomplished through transformation of variables and application of generalized linear model and support vector regression. Proposed models are built into an online tool that can help transit planners and policy makers: (a) estimate the capacity and operating cost of a DAR system needed to provide the desired level of service, (b) explore tradeoffs between system costs and levels of service, and (c) compare the cost of providing DAR service with other transportation alternatives (e.g., taxi, conventional transit).     

D值法反弯点高度EXCEL表的研制

文中推导补充了倒三角形荷载下的标准反弯点公式。对顶点集中荷载、均布荷载、倒三角形荷载下的标准反弯点公式及上、下层梁线刚度改变,上、下层柱高度改变时反弯点高度比的修正公式进行了验算,编制了EXCEL表格,以及通过算例验证了计算表格的正确性。     

某型不平衡式发射装置泄放提前对出管速度的影响

通过简化气动不平衡发射原理,建立数学模型通过仿真计算得出不同发射深度及不同提前泄放距离对武器出管速度的影响程度,为空气发射系统阀件的陆上或艇上联调试验时的安全对水深状态调整仪的调整提供判断依据。     

集装箱轮胎式场桥节能减排的探讨

为建设绿色港口,天津港太平洋国际集装箱码头有限公司对集装箱轮胎式场桥采用多项措施,进行节能减排改造。分别介绍采用辅助措施对该场桥进行节能减排的做法和用岸电取代柴油机驱动的做法。着重探讨了低架直流滑触线的应用。最后提出了需要解决的问题。