一种基于多源数据的网络实体推断方法

网络空间中的实体推断是网络空间测绘研究的重要内容之一,主要通过综合多源数据实现对网络空间中各类实体的分类与识别。本文首先提出了网络空间的实体分类模型,基于此模型提出了一种低开销的网络实体探测分类方法。首先对于探测发现的IP地址,采用别名解析技术将属于一个设备的多个IP映射为一个网络实体;然后采用决策树对网络实体分类进行粗粒度分类;最后,再基于贝叶斯网络进行详细分类。为验证分类效果,以江苏省某市为例进行了探测分析并与备案数据进行了对比,试验结果表明该方法可以有效地对网络空间中的各类实体进行判别,从而为网络空间地图构建、态势分析等应用提供技术支撑。     

网络最大流与最小割集的矩阵算法

本文给出了解决运输问题为中心的一类特殊的线性规划问题的新的、简便的算法.网络最大流与最小割集的矩阵算法,不仅能解决许多这类问题,而且能使最小费用流、分配问题和运输问题容易通过计算机来实现.     

面向生产过程的智能车间数字孪生建模及应用

数字孪生技术具有虚实融合的特性,智能车间数字孪生可以使生产过程透明化,利用实时数据可以有效指导车间生产。为实现基于数字孪生的生产过程可视化管控,提出了面向生产过程的智能车间数字孪生建模及应用。首先,建立了智能车间数字孪生系统体系架构。然后对系统实现的3项关键技术——基于点云拟合的三维几何模型构建方法、面向数据交互的对象链接与嵌入的过程控制统一架构（Object linking and embedding for process control unified architecture,OPC UA）信息建模方法、以及多源异构数据集成及虚实映射数据快速匹配方法进行了详细阐述;最后,对某发动机制造车间进行了数字孪生的实现,验证了所提方法的正确性和有效性。     

A new grid deformation technology with high quality and robustness based on quaternion

Quality and robustness of grid deformation is of the most importance in the field of aircraft design, and grid in high quality is essential for improving the precision of numerical simulation. In order to maintain the orthogonality of deformed grid, the displacement of grid points is divided into rotational and translational parts in this paper, and inverse distance weighted interpolation is used to transfer the changing location from boundary grid to the spatial grid. Moreover, the deformation of rotational part is implemented in combination with the exponential space mapping that improves the certainty and stability of quaternion interpolation. Furthermore, the new grid deformation technique named ‘‘layering blend deformation' is built based on the basic quaternion technique, which combines the layering arithmetic with transfinite interpolation(TFI) technique. Then the proposed technique is applied in the movement of airfoil, parametric modeling, and the deformation of complex configuration, in which the robustness of grid quality is tested. The results show that the new method has the capacity to deal with the problems with large deformation, and the ‘‘layering blend deformation' improves the efficiency and quality of the basic quaternion deformation method significantly.     

基于高拟真度模型的高超声速飞行器静气动弹性优化

为解决基于计算流体动力学(CFD)和计算结构动力学(CSD)高拟真度模型的静气动弹性优化过程中模型更新自动化困难、求解速度慢的难点,提出了基于几何主模型技术的CFD/CSD一体化参数化建模方法和基于网格单元修正的常体积四面体(CVT)数据交换技术,并引入响应面模型来降低气动弹性优化求解难度.通过AGARD 445.6机翼静气动弹性分析对上述方法的可行性和有效性进行了验证;并以某高超声速飞行器为例,采用基于二次响应面的多目标优化算法进行了CFD/CSD气动弹性分析与优化,优化后飞行器升阻比增加16%,结构质量减少9%,且响应面模型精度拟合误差不超过1.5%.计算结果表明:所发展的CFD/CSD一体化参数化建模与优化方法能够有效地解决高拟真度模型的静气动弹性优化问题.      

面向视觉SLAM的快速均匀特征点提取方法CSCD

针对现有特征点提取方法中特征点提取结果冗余且均匀性差,导致SLAM定位精度及计算效率低的问题,提出了一种面向视觉SLAM的快速均匀特征点提取方法。在该算法的特征点提取部分,创新性地根据目标特征点提取数量对图像进行网格划分,使得特征点均匀分布在整幅图像中。同时,提出了一种兼顾全局和局部信息的均匀性评价标准,更符合视觉SLAM对特征点分布的要求。在NVIDIA Jetson TX2嵌入式平台上进行了实验验证,实验结果表明,新提出的特征点提取方法降低了特征信息冗余及特征信息缺失的概率,提升了SLAM定位精度,在计算资源有限的平台上具有实际应用价值。     

考虑承载面最大位移约束的结构拓扑优化方法

在实际工程问题中,存在着一类承受分布力载荷作用的工程结构。为了实现此类结构的刚度设计要求,提出限制承载面变形的拓扑优化设计新模型。模型采用KS包络函数对承载面节点位移进行凝聚化处理,并推导了相应的伴随方程和敏度表达式。遵循独立连续映射法建模方式,采用一阶和二阶泰勒展开分别得到约束函数和目标函数的显式表达式。由此将优化问题转换为一系列标准二次规划子问题,采用序列二次规划算法进行高效、稳健求解。通过二维、三维数值算例验证了提出模型的可行性和有效性。结果表明,所提出的列式和相应的优化求解算法能有效控制结构局部区域的最大变形量。     

Anti-plane problem of four edge cracks emanating from a square hole in piezoelectric solids

By constructing a new numerical conformal mapping and using the Stroh-type for-mulism, an anti-plane problem of four edge cracks emanating from a square hole in piezoelectric solids is investigated. The explicit expressions of the complex potential function, field intensity fac-tors, energy release rates and mechanical strain energy release rate near the crack tip are obtained under the assumptions that the surfaces of the cracks and hole are electrically permeable and elec-trically impermeable. Numerical examples are presented to show the influences of the geometrical parameters of defects and applied mechanical/electrical loads on the energy release rate and mechanical strain energy release rate under two electrical boundary conditions.     

基于序列-图像映射的航天器智能故障诊断方法

卫星组网是未来航天的发展大趋势,要保证众星在轨安全可靠稳定运行,要求单星具备高精度的在轨自主故障诊断能力。本文针对航天器控制系统故障闭环传播和数据维数高的特点,结合某航天器的地面测试数据,首先对高维耦合序列数据进行处理,实现序列到灰度图像的映射,然后采用卷积神经网络完成高精度同一故障部件的故障诊断。通过将所提方法与K邻近算法、基于主成分分析的K邻近算法等非图像化机器学习算法进行对比验证,说明了本文所提方法的有效性。     

Comparison of Landsat OLI,ASTER, and Sentinel 2A data in lithological mapping : A Case study of Rich area (Central High Atlas,Morocco)

The eastern part of the Rich area consists of the massive Paleozoic and Meso-Cenozoic cover formations that present the geodynamic development of the study area, where is characterized by various carbonate facies of Jurassic age. The geographical characteristic of the study area leaves the zone difficult to map by conventional methods. The objective of this work focuses on the mapping of the constituent lithological units of the study area using multispectral data of Landsat OLI, ASTER, and Sentinel 2A MSI. The processing of these data is based on a precise methodology that distinguishs and highlights the limits of the different lithological units that have an approximate similarity of spectral signature. Three techniques were used to enhance the image including Principal Component Analysis (PCA), Minimum Noise Fraction (MNF), and Independent Component Analysis (ICA). Lithological mapping was performed using two types of supervised classification : Maximum likelihood classifier (MLC) and Support Vector Machine (SVM).The results of processing data show the effectiveness of Sentinel 2A data in mapping of lithological units than the ASTER and Landsat OLI data. The classification evaluation of two methods of the Sentinel 2A MSI image showed that the SVM method give a better classification with an overall accuracy of 93,93% and a Kappa coefficient of 0.93, while the MLC method present an overall accuracy of 82,86% and a Kappa coefficient of 0.80. The results of mapping obtained show a good correlation with the geological map of the study area as well as the efficiency of remote sensing in identification of different lithological units in the Central High Atlas.