多尺度形态滤波及弹性匹配技术在类星体谱线识别中的应用

本文提出了一种类星体谱线证认方法。首先针对特征为极值点的信号，研究了多尺度膨胀（腐蚀）关于极值点数的两种重要特性及其应用。其一是单调率特性，根据它自动选择滤波器尺度，有效地滤除脉冲噪声；另一种是单调性，它是＂从粗到精＂策略来重新恢复极值特征位置的理论基础。根据这些性质，对光谱进行多尺度膨胀（腐蚀）和特征恢复，以滤除脉冲噪声而不影响谱线特征。然后研究弹性匹配技术应用于谱线证认，并指出了匹配方法中参量的物理意义。该方法对其他一些应用领域也行之有效     

三维散乱数据三角形网格逼近的一种算法

以激光－机器视觉测量方式得到的曲面数据云为基础，对曲面密集３维散乱数据用线性逼近进行三角形网格拟合。根据激光测量方式和３维点群分布的特点，应用八叉树空间分割原理，对密集散乱点群采用空间分区存储，建立八叉树拓扑关系，加快几何建模速度。     

基于EMST的平面点集Delaunay三角剖分

提出一种基于欧几里德最小支撑树(EMST)的平面点集Delaunay三角剖分算法.该算法使用线性时间的随机算法求出平面点集的EMST,逐次加入一边构成三角网络,按照最小角最大化的三角化准则,通过局部变换得到平面点集的Delaunay三角剖分.采用的随机化算法有效节省了寻找EMST的计算时间,提高了整个算法的效率.     

Generating subdivision surfaces from profile curves

The construction of freeform models has always been a challenging task. A popular approach is to edit a primitive object such that its projections conform to a set of given planar curves. This process is tedious and relies very much on the skill and experience of the designer in editing 3D shapes. This paper describes an intuitive approach for the modeling of freeform objects based on planar profile curves. A freeform surface defined by a set of orthogonal planar curves is created by blending a corresponding set of sweep surfaces. Each of the sweep surfaces is obtained by sweeping a planar curve about a computed axis. A Catmull-Clark subdivision surface interpolating a set of data points on the object surface is then constructed. Since the curve points lying on the computed axis of the sweep will become extraordinary vertices of the subdivision surface, a mesh refinement process is applied to adjust the mesh topology of the surface around the axis points. In order to maintain characteristic features of the surface defined with the planar curves, sharp features on the surface are located and are retained in the mesh refinement process. This provides an intuitive approach for constructing freeform objects with regular mesh topology using planar profile curves.     

模糊概率SDG模型及故障推理方法

基于符号有向图(SDG)的故障诊断方法具有良好的完备性和易于解释性,但其存在分辨率差的缺陷,为此提出基于模糊概率SDG模型和贝叶斯推理的半定量故障诊断方法.用模糊变量表示节点变量,用条件概率表(CPT)表达节点间的定性因果关系,利用贝叶斯推理和回溯搜索找出故障源候选解的集合,并对候选解进行排序.最后建立了某卫星一次电源系统的诊断模型.仿真结果表明,该方法有效地提高了诊断的分辨率,适用于航天器在轨故障诊断.     

Duplex fitting of zero-level and offset surfaces

Offset surfaces play an important role in various CAD/CAM applications. Given a set of oriented points, we propose a hierarchical method in this paper to fit both the zero-level surface and its offset surface with a single implicit function. The implicit function is formed by compactly supported radial basis functions (CSRBFs). Different from other existing methods in literature, our approach reconstructs an implicit function which interpolates or approximates both the zero-level surface and the offset surface of a given point set, simultaneously. Employing locally supported functions leads to an efficient computational procedure, while the coarse-to-fine hierarchy makes our approach insensitive to the density of scattered data and allows us to reconstruct large parts of missing data. The performance of our method is demonstrated by a number of examples and the application of adaptive slicing hollowed models in rapid prototyping.     

概率SDG 模型及故障分析推理方法

符号有向图（SDG）是用来表示大规模复杂系统中变量之间因果影响关系的一种重要工具,但其存在一些不易克服的缺点.为此,首先提出一种新的模型--概率SDG模型,用条件概率描述故障之间的传递关系;然后在概率SDG模型的框架下,提出一种故障分析诊断的推理方法,即利用图消去算法和连接树算法进行贝叶斯推理,并计算出故障概率.最后以65 t/h锅炉系统为例,研究建立其概率SDG模型,并在此基础上验证了上述模型和推理方法的有效性.     

基于符号模型检测的SDG故障诊断解形式化验证

由于定量信息和非线性因果关系的丢失,SDG的故障诊断解需要进一步的进行校核与验证。创新地将SDG故障诊断解的验证置于符号模型检测框架中进行研究,提出了基于符号模型检测的SDG故障诊断形式化验证方法。首先扩展、转换了SDG模型的有限状态变迁系统形式化描述,建立了SMV模型;其次引入故障传播时间建立了模型观测变量的动态验证信息,并基于步进式监控分析了动态验证策略,将SDG正向推理扩展建模为动态推理验证;然后面向符号模型检测扩展了动态推理验证过程的SMV模型,提出了验证算法SSDGFD_ SMC;最后,通过一个实例验证了算法的有效性。     

利用角度签名进行3维表面配准

3维表面的配准在3维物体重建、场景检测和物体识别过程中起着重要的作用。为此提出了一种新的3维表面表示方法——角度签名(angle signature),并将其用于3维表面配准。该表示方法将表面的局部几何信息表示成为1维的向量,具有对刚体变换的不变性。由于其简洁的表示方式,可以实现表面的快速配准。此外,该方法较其他3维表面的表示方法具有更强的鲁棒性。在实际应用中,为了提高表面配准的速度,首先筛选出特征点,然后利用特征点寻找表面之间的对应关系,从而将刚体变换的参数求出,实现表面的配准。实验结果表明,采用角度签名实现物体表面配准具有较快的速度和较高的精度。     

Tetrahedra Based Adaptive Polygonization of Implicit Surface Patches

This paper presents a tetrahedra based adaptive polygonization technique for tessellating implicit surface patches. An implicit surface patch is defined as an implicit surface bounded by its intersections with a set of clipping surfaces and which lies within an enclosing tetrahedron. To obtain the polygonization of an implicit surface patch, the tetrahedron containing the patch is adaptively subdivided into smaller tetrahedra according to the criteria introduced in the paper. The result is a set of tetrahedra each containing a facet approximating the surface. The intersections between the facets and the clipping surfaces are used to locate the surface patch boundary. Ambiguous results in generating the facets for highly curved surfaces or surfaces with singular points are also addressed. The result of the polygonization is a set of triangular facets that can be used for visualization and numerical analysis. The proposed method is also suitable for locating the intersection of two implicit surfaces.