Investigation on optimization design of equivalent water depth truncated mooring system

The oil industry is now increasingly concentrating their efforts and activities in connection with developing fields in deeper waters, ranging typically from 500 m to 3000 m worldwide. However, the modeling of a full-depth system has become difficult presently; no tank facility is sufficiently large to perform the testing of a complete FPS with compliant mooring in 1000 m to 3000 m depth, within reasonable limits of model scale. Until recently, the most feasible procedure to meet this challenge seems to be the so-called “hybrid model testing technique”. To implement this technique, the first and important step is to design the equivalent water depth truncated mooring system. In this work, the optimization design of the equivalent water depth truncated mooring system in hybrid model testing for deep sea platforms is investigated. During the research, the similarity of static characteristics between the truncated and full depth system is mainly considered. The optimization mathematical model for the equivalent water depth truncated system design is set up by using the similarity in numerical value of the static characteristics between the truncated system and the full depth one as the objective function. The dynamic characteristic difference between the truncated and full depth mooring system can be minished by selecting proper design rule. To calculate the static characteristics of the mooring system, the fourth order Runge-Kutta method is used to solve the static equilibrium equation of the single mooring line. After the static characteristic of the single mooring line is calculated, the static characteristic of the whole mooring system is calculated with Lagrange numerical interpolation method. The mooring line material database is established and the standard material name and the diameter of the mooring line are selected as the primary key. The improved simulated annealing algorithm for continual & discrete variables and the improved complex algorithm for discrete variables are employed to perform the optimization calculation. The C++ programming language is used to develop the computer program according to the object-oriented programming idea. To perform the optimization calculation with the two algorithms mentioned above respectively and the better result is selected as the final one. To examine the developed program, an example of equivalent water depth truncated mooring system optimum design calculation on a 100,000-t, turret mooring FPSO in water depth of 320 m are performed to obtain the conformation parameters of the truncated mooring system, in which the truncated water depth is 160 m. The model test under some typical environment conditions are performed for both the truncated and the full depth system with model scale factor λ=80. After comparing the corresponding results from the test of the truncated system with those from the full depth system test, it’s found that the truncated mooring system design in this work is successful. Supported by the National Natural Science Foundation of China (Grant Nos. 10602055 and 40776007) and the Natural Science Foundation of China Jiliang University (Grant No. XZ0501)     

A primitive-variable Riemann method for solution of the shallow water equations with wetting and drying

A Riemann flux that uses primitive variables rather than conserved variables is developed for the shallow water equations with nonuniform bathymetry. This primitive-variable flux is both conservative and well behaved at zero depth. The unstructured finite-volume discretization used is suitable for highly nonuniform grids that provide resolution of complex geometries and localized flow structures. A source-term discretization is derived for nonuniform bottom that balances the discrete flux integral both for still water and in dry regions. This primitive-variable formulation is uniformly valid in wet and dry regions with embedded wetting and drying fronts. A fully nonlinear implicit scheme and both nonlinear and time-linearized explicit schemes are developed for the time integration. The implicit scheme is solved by a parallel Newton-iterative algorithm with numerically computed flux Jacobians. A concise treatment of characteristic-variable boundary conditions with source terms is also given. Computed results obtained for the one-dimensional dam break on wet and dry beds and for normal-mode oscillations in a circular parabolic basin are in very close agreement with the analytical solutions. Other results for a forced breaking wave with friction interacting with a sloped bottom demonstrate a complex wave motion with wetting, drying and multiple interacting wave fronts. Finally, a highly nonuniform, coastline-conforming unstructured grid is used to demonstrate an unsteady simulation that models an artificial coastal flooding due to a forced wave entering the Gulf of Mexico.     

Genetic alloy design based on thermodynamics and kinetics

A theory-guided computational approach for alloy design is presented. Aimed at optimising the desired properties, the microstructure is designed and an alloy composition optimised accordingly, combining criteria based on thermodynamic, thermokinetic and mechanical principles. A genetic algorithm is employed as the optimisation scheme. The approach is applied to the design of ultra-high strength stainless steels. Three composition scenarios, utilising different strengthening precipitates (carbides, Cu and NiAl/Ni₃Ti), are followed. The results are compared to a variety of existing commercial high-end engineering steels, showing that the design strategy presented here may lead to significant improvements in strength beyond current levels.     

一种基于高斯混合模型的改进EM算法研究

针对传统EM算法存在估计参数不具有最优性,以及在参数估计中需要人工参与等问题,提出一种基于高斯混合模型的改进EM算法。采用无人工参与的无监督思想,获取高斯混合模型对直方图拟合的最优参数组合。实验表明,该算法不仅能够快速地估计模型参量,而且能够给出最优参数,并在图像增强中使细节更明显,对比度更适中。     

基于视场拼接的全视差三维显示系统

提出了一种新的基于视场拼接的全视差三维显示方法及图像生成方案.系统核心部分由一个微投影机阵列、一个反射光路和一个散射屏组构成,图像生成方案采用基于OpenGL的算法实现.为了验证所提出的基于视场拼接理论的正确性,利用液晶显示器、菲涅耳镜组、定向散射屏和背投式反射光路搭建了实验样机.该装置可以在更紧凑的系统结构下显示包括横向视差和纵向视差在内的三维图像,并且通过图像生成算法的配合实现了动态三维显示效果.     

一种裕量最大的高速载波比特功率分配算法

在国家电网公司Q/GDW 1379.4-2013技术规范对智能电能表载波通信单元功率消耗的限定要求下,为保障低压远程电力集抄台区本地通信链路的传输速率稳定可靠,给智能用电实时交互平台提供带宽支持,提出了一种裕量最大的高速载波比特功率分配算法。该算法以兼并窄带载波和宽带载波优势的G3-PLC技术为应用对象,使用约束注水法限定各子载波的传输比特数,根据时变的电力信道增益自适应调整比特功率分配方案,并响应通信服务质量QoS对系统误码率和目标传输速率的要求,结合信噪比门限算法对约束注水法进行界定和优化,得到了功率裕量最大化的表达式。仿真结果表明：提出的算法优于低反馈开销算法,能够适应低压电力线信道。在系统目标传输速率为200kbps时,达到了最大裕量值20,极大程度地降低了通信单元调制解调芯片实际的功率消耗。     

一种新型的RS-422总线数据处理算法研究与实现

为了满足某型机试飞数据中新型RS-422总线参数的实时监控和事后数据处理需求,提出了针对该新型RS-422总线参数的算法设计和实现方案。通过分析该新型RS-422总线参数的通信协议及数据包格式,决定采用调整机载格栅中数据的帧结构排放以及重置带头中参数采样率的方式,实现了参数的解析及还原算法,并设计了相应的实时监控以及事后处理软件。该软件已经成功应用于该型机的飞行试验中,为飞机飞行安全监控以及事后数据处理分析提供了有力保障。     

面向绿色智能制造的高维多目标动态作业车间调度优化

在当前环境问题日益严峻情况下,绿色智能制造受到广泛关注。在动态柔性作业车间基础上考虑不同机器状态下的能耗情况、机器使用节能方法,构建以极小化总能耗、最大完工时间、机器总负荷和产品质量稳定性为目标的高维多目标绿色动态柔性作业车间调度模型,并设计改进的灰狼优化IMOGWO算法求解该问题。首先,采用反向学习初始化种群策略,以扩大种群多样性;然后,依据多目标问题和标准GWO算法的特点提出多级官员领导机制,并引入POX交叉和逆序变异算子;最后,改进精英保留策略用于多目标优化算法。为证明算法的有效性,设计两组仿真实验分别对三种算法进行比较。实验结果表明,运用本文改进的IMOGWO算法求解多目标问题有更好的收敛性和分布性。     

Optimal Control for Multiscale Elliptic Equations with Rough Coefficients

This paper concerns the convex optimal control problem governed by multiscale elliptic equations with arbitrarily rough $L^\infty$ coefficients, which has not only complex coupling between nonseparable scales and nonlinearity, but also important applications in composite materials and geophysics. We use one of the recently developed numerical homogenization techniques, the so-called Rough Polyharmonic Splines (RPS) and its generalization (GRPS) for the efficient resolution of the elliptic operator on the coarse scale. Those methods have optimal convergence rate which do not rely on the regularity of the coefficients nor the concepts of scale-separation or periodicity. As the iterative solution of the nonlinearly coupled OCP-OPT formulation for the optimal control problem requires solving the corresponding (state and co-state) multiscale elliptic equations many times with different right hand sides, numerical homogenization approach only requires one-time pre-computation on the fine scale and the following iterations can be done with computational cost proportional to coarse degrees of freedom. Numerical experiments are presented to validate the theoretical analysis.     

一种新的求解拟单调变分不等式的压缩投影算法

2020年Liu和Yang提出了求解Hilbert空间中拟单调且Lipschitz连续的变分不等式问题的投影算法,简称LYA。本文在欧氏空间中提出了一种新的求解拟单调变分不等式的压缩投影算法,简称NPCA。新算法削弱了LYA中映射的Lipschitz连续性。在映射连续、拟单调且对偶变分不等式解集非空的条件下得到了NPCA所生成点列的聚点是解的结论。当变分不等式的解集还满足一定条件时,得到了NPCA的全局收敛性。数值实验结果表明NPCA所需的迭代步数少于LYA的迭代步数,NPCA在高维拟单调例子中所需的计算机耗时也更少。