Mapped infinite elements for three-dimensional multi-region boundary element analysis

A formulation for an infinite boundary element (BE) is presented, which allows the modelling of infinite surfaces. The concept is that the finite surface is mapped to an infinite surface using special mapping functions. Using such mapping functions together with linear and quadratic interpolation for the displacements and the tractions, respectively, the desired decay behaviour can be modelled. The implementation of the proposed infinite elements becomes straightforward, since the Cauchy principal value, as well as the free term, are evaluated for the finite and infinite BEs with exactly the same techniques. The element developed can be used in a multi-region BE analysis of piecewise homogeneous domains, or for domains with joints and faults. The accuracy of the element is tested on some benchmark problems. Finally, a practical application in tunnelling is shown. Copyright © 2004 John Wiley & Sons, Ltd.     

多区域输电阻塞管理的拉格朗日松驰分解算法

提出一种新的基于增广拉格朗日松驰的区域分解最优潮流算法,将一个大的最优潮流问题分解成多个区域子问题,并用此算法求解多区域电力市场输电阻塞管理问题,与现有的其他方法相比,该算法的主要优点在于无需在原始网络模型的基础上增加任何虚拟发电机或负荷,通过将该算法与电力市场实时平衡机制相结合,多区域有力阻塞管理问题可以分解为单区域二次规划子问题。这些子问题可以顺序求解也可以并行求解。采用这一方法,所有的区域市场独立调度员在得到不到其他区域网络信息的情况下仍然可以相互协作消除网络阻塞,在这一过程中,惟一需要进行区域间交换的信息是与区域间“耦合”约束相对应的拉格朗日乘子,最后,通过分析3区域的IEEE RTS－96标准测试系统说明了该方法的有效性。     

Numerical Solutions of Diffusion Equations in Multi-Dimensional Slab Geometry by Fourier Expansions

Solutions of multi-dimensional neutron diffusion equations in Cartesian coordinates are obtained in the form of regionwise multi-dimensional Fourier series. Equations for two- and three-dimensional problems are derived. A critical and a source problem in two dimensions, and a one-regional source problem in three dimensions are numerically studied.

Two kinds of Fourier series are numerically examined from the viewpoint of rapidity of convergence of the series.

To obtain the value of the flux more accurately, a method is presented which contributes to improvement of the flux profile.     

基于多角度多区域特征融合的苹果分类方法

日常生活中人们分拣辨别不同种类的苹果需要消耗大量的人力物力,为解决这一问题,提出了一种基于多角度多区域特征融合的苹果图像分类方法。首先,收集五类总共329个苹果,使用手机摄像头从上面、下面和3个不同侧面共五个角度采集每个苹果的图像,每个图像裁剪若干个（1~9）区域块;其次,每个区域块用颜色直方图向量来表示,多个区域块的直方图向量通过首尾相连进行融合,以此生成一个图像的表示;最后,将得到的329个样本数据用12种分类器进行分类比较。实验结果表明,当多角度多区域图像特征融合时,分类效果总是好于单角度单区域,而且越多越好;当使用5个角度的图像,每个图像裁剪9个区域时,偏最小二乘（PLS）分类器的分类精度达到97.87%,好于深度学习。所提方法操作简单、精度较高,算法复杂度为4n,n为图像裁剪区域块总数,可以推广成手机应用,并应用到更多水果和植物图像分类上。     

考虑跨区能流交互计划的多区域电-气综合能源系统分散调度方法

针对多区域电-气互联系统优化调度问题,提出考虑联络线、联络管道能流交互计划的分散式调度方法。首先,利用二阶锥松弛方法将气网潮流方程线性化;在区域间,通过优化联络线与联络管道能流交互计划,对机组出力进行优化配置以促进互联区域的风电消纳,并以单个区域为决策主体建立满足联络线与联络管道约束的集中式优化模型。然后,分析了多区域电-气互联系统能量流解耦机制,并基于标准交替方向乘子法,得到分散式优化算法,即同步交替方向乘子法(synchronous-alternating direction method of multipliers,S-ADMM),再利用上述算法对集中式模型进行重构,建立一种完全分散式的调度模型。最后,在不同规模的多区域电-气互联系统中开展算例分析,其结果表明:所提算法有较优的收敛性;通过联络线与联络管道的互联方式使系统运行最优;多区域电-气互联系统可改变联络线峰谷差率,使各区域发电资源达到配置最优,并减少了区域弃风量,降低了运行成本,可为多区域能源系统优化运行提供参考。     

一种预测TP347H钢长时持久强度的方法

基于多区LMP法,利用TP347H钢的高温（700℃、750℃）短时（≤5×10^3h）试验数据预测其长时持久强度（600～750℃,5×10^3～2×10^5h）．结果表明：在应力-时间图中根据口／dT。的特定比值对应力分区,用低应力-长时区LMP参数中的C值计算长时持久强度,其预测值与真实值吻合良好;与传统的单区LMP法相比,多区LMP法的应用不仅显著降低了持久强度的过估倾向而且大大缩短了试验时间,为这类钢的长时持久强度评估提供了准确而有效的方法．     

基于多区非平衡模型的稳压器动态仿真与验证

采用FORTRAN程序设计语言,基于稳压器多区非平衡模型和吉尔数值求解方法,开发了稳压器动态仿真程序NEP MR。计算结果与美国希平港核电站稳压器74MW和105MW甩负荷的试验结果进行对比,总体趋势符合良好。NEP MR程序可较好地反映瞬态甩负荷过程中稳压器内部控制体的温度分层现象。在稳压器喷淋器开启和关闭瞬间,汽相和液相控制体之间的界面流量出现突跳现象。计算结果证明了多区非平衡模型建模和NEP MR程序仿真的合理性。     

机载AIS监视性能仿真研究

针对机载AIS由于时隙冲突导致的监视性能下降的问题,提出通过分区域接收提高检测概率的方法.通过分析AIS系统的接入过程,深入研究影响系统监视性能的因素,利用MATLAB,基于SOTDMA协议构建全新结构下的机载AIS系统的仿真模型.仿真结果确定了时隙冲突、系统容量和负载之间的关系,表明分区域接收能有效提高检测概率,从而为工程应用提供了有益的参考.     

线性序约束关系的无损连接分解*

对线性序约束数据库中的数据依赖和无损连接分解进行了研究.介绍了线性序约束数据库的一些基本概念,提出了线性序约束关系中多区域存在依赖和分组多区域存在依赖的概念,证明了变量集满足变量独立和多区域存在依赖是进行模式无损连接分解的充要条件.探讨了变量集在坐标线性变换下保持良性分解的情形.     

Radially and azimuthally dependent resonance self-shielding treatment for general multi-region geometry based on a unified theory

A unified resonance self-shielding method, which can treat general sub-divided fuel regions, is developed for lattice physics calculations in reactor physics field. In a past study, a hybrid resonance treatment has been developed by theoretically integrating equivalence theory and ultra-fine-group slowing-down calculation. It can be applied to a wide range of neutron spectrum conditions including low moderator density ranges in severe accident states, as long as each fuel region is not sub-divided. In order to extend the method for radially and azimuthally sub-divided multi-region geometry, a new resonance treatment is established by incorporating the essence of sub-group method. The present method is composed of two-step flux calculation, i.e. ‘coarse geometry + fine energy’ (first step) and ‘fine geometry + coarse energy’ (second step) calculations. The first step corresponds to a hybrid model of the equivalence theory and the ultra-fine-group calculation, and the second step corresponds to the sub-group method. From the verification results, effective cross-sections by the new method show good agreement with the continuous energy Monte-Carlo results for various multi-region geometries including non-uniform fuel compositions and temperature distributions. The present method can accurately generate effective cross-sections with short computation time in general lattice physics calculations.