Optimizing natural gas pipeline transmission with nonuniform elevation: A new initialization approach

In this paper, we develop an iterative piecewise linear approximation approach with a novel initialization method to solve natural gas pipeline transmission problems with the nonuniform network elevation. Previous approaches, such as energy minimization methods, cannot be applied to solve problems with the nonuniform network elevation because they exclude pressure range constraints, and thus provide solutions far from optimum. We propose a new initialization model that considers pressure range constraints and improves the optimality of the solutions and the computational efficiency. Furthermore, we extend the energy minimization methods and provide the necessary conditions under which the extended methods operate in networks with the nonuniform elevation. We test the performances of the methods with previously reported pipeline networks from the literature, with the open data set GasLib, and with our industrial collaborator. The initialization approach is shown to be more efficient than the method with fixed initial breakpoints. The newly proposed initialization approach generates solutions with a higher accuracy than the extended energy minimization methods, especially in large‐size networks. The proposed method has been applied to natural gas transmission planning by the China National Petroleum Corporation and has brought a direct profit increase of 330 million U.S. dollars in 2015‐2017.     

马汉海权论的形成及其影响

19世纪末,美国海军上校马汉提出了系统的海权论观点,主要内容是:海洋对濒海国家的生存与发展有决定性的意义,而要拥有海权就必须发展强大的海军并在海外取得补给基地.这一理论不仅准确地反映了当时欧关列强争夺海外殖民地的趋势,更为这种争夺提供了理论依据,故一旦出现立即风靡全球,对世界各国产生了广泛而深远的影响.     

浅论工程装备试生产过程中的工艺评审及工艺鉴定

本文通过分析现行相关标准中工艺评审和工艺鉴定的内涵,说明了工程装备首批产品试生产过程中实施工艺评审做法的不合理之处,探讨了实施工艺鉴定的可行性以及要求、内容和方法,对完善工程装备首批产品质量评审工作,保证后续批量生产质量具有借鉴意义,以期共同探讨。     

三维视觉运动建模中碰撞检测算法研究

三维视觉建模是建立虚似现实 (VR)系统的基础 ,运动建模是三维视觉建模的重要组成部分。研究了运动建模中碰撞检测算法     

虚拟现实系统的建模方法

采用先进的建模方法 ,开发组织和管理复杂的虚拟环境 ,不仅能够提高开发效率 ,甚至关系到项目开发的成败。研究了面向对象和面向智能体两种虚拟现实 (VR)系统设计的基本方法。