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.     

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.     

大跨径拱桥缆索施工支架非线性受力特性分析

随着钢管混凝土拱桥跨径的增大,缆索吊装施工过程中,塔架的受力安全性问题备受关注,但主索的计算为简化的理论计算,不考虑主索滑移及塔架偏位对主索受力的影响,导致塔架受力计算不够精确。以某430 m大跨度钢管混凝土拱桥为例,建立索塔一体化并考虑主索非线性及滑移的有限元模型,考虑塔架偏位对主索及塔架变形与受力的影响,将得到的有限元受力分析结果与现有解析方法的求解结果对比分析,结果表明:有限元方法计算结果偏大,与解析法差距在10%以内,说明考虑主索滑移及塔架偏位时结构受力更不利,此种模拟方式能够较精确地计算主索及塔架的变形及受力特性,为钢管混凝土拱桥的施工提供指导。     

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。     

邢衡高速公路邢台段互通式立交设计技术要点

通过某互通式立交设计实践,阐述采用的设计原则和技术要点。结果证明,所提出的设计方案是成功之举,值得同行借鉴。     

沪通长江大桥主塔2700 t·m附壁塔吊设计与施工

沪通长江大桥主航道桥为公铁两用双主塔钢桁梁斜拉桥,主塔总高度为330 m,采用C60钢筋混凝土结构,塔柱横梁以上为倒Y形。为满足斜拉索索盘上桥、上塔柱区域重型钢锚梁高精度吊装等需求,在中塔柱处采用2700 t·m自升式塔吊+托架+附墙结构的附壁式设计,托架结构由钢靴、压杆、压杆附墙、压杆联结系、支撑框组成。采用MIDAS/Civil软件分析了塔吊与主塔的共振影响;通过张拉精轧螺纹筋、槽口灌浆保证钢靴处有效传力,灌注微膨胀混凝土保证压杆处刚度及稳定性;通过空载、静载和动载试验以及信息化监控确保施工期间整体结构安全。附壁塔吊相比于传统落地式塔吊,既可充分发挥吊重能力,又能显著减少标准节用量及安装工期。     

融合智能匹配与信息化管理的船舶主推进设备

从船舶主推进设备的发展现状出发,分析船舶主推进设备的智能控制和信息化管理需求及当前存在的问题。在此基础上,提出融合智能匹配与信息化管理的船舶主推进设备发展思路和措施,详细阐述相关措施在提升船舶主推进设备性能方面的应用前景和良好效果。