基于ConvMixer架构的高效点云分类方法

近年来,视觉Transformer模型在点云分类等三维计算机视觉任务中显现出潜在的优越性,但其有效性来源仍然模糊不清。研究它们在视觉任务中的性能是完全归功于Transformer结构本身的优越性,还是至少部分得益于使用局部块作为输入表示,是非常必要的。受此启发,本文提出了一种简单但仍然有效的点云分类和分割模型PointConvMixer,用ConvMixer架构取代了Point-BERT中的标准Transformer。PointConvMixer在ModelNet40数据集上的整体分类准确率达到92.3%,在ShapeNet Parts数据集上进行点云部分分割时mIOUI和mIOUC分别为85.4%和83.9%,均优于基于Transformer的对比模型。此外,本文还进一步提出PPFConvMixer,其利用高效的局部特征描述符PPF增强了PointConvMixer,从而优化了点云分类性能。在查询半径为0.25m时,PPFConvMixer的总体分类准确率达到了93.8%。

Near Crack Line Elastic-Plastic Analysis for an Infinite Plate Loaded by a Pair of Point Shear Forces

The near crack line analysis method was used to investigate a crack loaded by a pair of point shear forces in an infinite plate in an elastic-perfectly plastic solid. The analytical solution was obtained, that is the elastic-plastic fields near crack line and law that the length of the plastic zone along the crack line is varied with external loads. The results are sufficiently precise near the crack line and are not confined by small scale yielding conditions.

ELASTIC-PLASTIC ANALYTICAL SOLUTIONS FOR AN ECCENTRIC CRACK LOADED BY TWO PAIRS OF ANTI-PLANE POINT FORCES

The improved near crack line analysis method was used to investigate an eccentric cracked plate loaded by two pairs of anti_plane point forces at the crack surface in an elastic_perfectly plastic solid. The analytical solutions of the elastic_plastic stress fields and displacements near the crack line have been found without the assumptions of the small scale yielding. The law that the length of the plastic zone along the crack line is varied with an external loads and the bearing capacity of an eccentric cracked plate are obtained.

POINT PATTERN MATCHING ALGORITHM BASED ON POINT PAIR TOPOLOGICAL CHARACTERISTICS AND SPECTRAL MATCHING

Most of the Point Pattern Matching (PPM) algorithm performs poorly when the noise of the point's position and outliers exist. This paper presents a novel and robust PPM algorithm which combined Point Pair Topological Characteristics (PPTC) and Spectral Matching (SM) together to solve the afore mentioned issues. In which PPTC, a new shape descriptor, is firstly proposed. A new comparability measurement based on PPTC is defined as the matching probability. Finally, the correct matching results are achieved by the spectral matching method. The synthetic data experiments show its robustness by comparing with the other state-of-art algorithms and the real world data experiments show its effectiveness.

NEAR CRACK LINE ELASTIC-PLASTIC ANALYSIS FOR A FINITE PLATE LOADED BY TWO PAIRS OF ANTIPLANE POINT FORCES

In this paper, the improved near crack line analysis method proposed in Refs. [1] and [2] is used to investigate a center crack loaded by two pairs of antiplane point forces in a finite plate in an elastic-perfectly plastic solid. And the analytical solutions are obtained, that is elastic-plastic stress fields near the crack line and the law that the length of the plastic zone along the crack line is varied with an external loads tr,ld the bearing capacity of a finite plate with a center crack. The results of this paper are sufficiently precise near the crack line, because the assumptions of the small scale yielding theory have not been used and no other assumptions have been taken.

Effect of acupuncture on acupoint "Yingxiang-Hegu" on Th1, Th2 cytokines and T-bet/GATA-3 of allergic rhinitis rats

Objective:To explore the effect of"Yingxiang-Hegu"on Th1,Th2-related cytokines and[2]transcription factors T-bet and GATA-3 in rats with allergic rhinitis.Methods:Rats were randomly divided into three groups:blank group,model group and acupoint group.The rat model of ovalbumin(OVA)AR was established,and the general condition of the rats was observed and scored.Acupuncture intervention was performed on the acupoint group on the second day after successful modeling,once per day for 20 min for 10 d.After intervention,the general behavior,behavioral score and histomorphological changes of nasal mucosa were observed.Eosinophils(EOS)were counted under microscope after nasal lavage smear staining,and the contents of total IgE,IFN-γ,IL-12,IL-4 and IL-5 in serum were detected by ELISA.Westernblot and IHC were used to detect the protein level and positive protein expression of specific transcription factors T-bet and GATA-3 in rat nasal mucosa.Results:After the establishment of the model,except for the blank group,the behavioral observation scores of rats in the model group and acupoint group were more than 5 points,indicating that the model was successful.After acupuncture intervention on acupoint"Yingxiang-Hegu",the behavioral score of rats in the acupoint group and western medicine group was significantly lower than that in the model group(P<0.05).Microscopic examination showed that the structure of nasal mucosa in the model group was obviously damaged,cilia were arranged discontinuously,uneven,local congestion and swelling,a large number of epithelial cells exfoliated and necrotic,goblet cell proliferation,obvious inflammatory cell infiltration.The pathological degree of nasal mucosa in the pair point group was significantly less than that in the model group.Compared with the model group,the levels of IFN-γ,IL-2 and IL-12 in serum were significantly increased,while IgE,IL-4,IL-5 and IL-6 were significantly decreased,GATA-3 protein and positive expression in nasal mucosa were significantly decreased and T-bet was significantly increased after acupuncture.Conclusion:Acupuncture at"Yingxiang-Hegu"can effectively improve the nasal sensitive symptoms and control nasal inflammation in AR rats.The mechanism may be that acupuncture at Yingxiang-Hegu can up-regulate the expression of T-bet,decrease the level of GATA-3,promote the production of Th1 cytokines and inhibit the synthesis and secretion of Th2 cells,thus restoring the immune balance of Th1 and Th2.

6DOF pose estimation of a 3D rigid object based on edge-enhanced point pair features

The point pair feature(PPF)is widely used for 6D pose estimation.In this paper,we propose an efficient 6D pose estimation method based on the PPF framework.We introduce a well-targeted down-sampling strategy that focuses on edge areas for efficient feature extraction for complex geometry.A pose hypothesis validation approach is proposed to resolve ambiguity due to symmetry by calculating the edge matching degree.We perform evaluations on two challenging datasets and one real-world collected dataset,demonstrating the superiority of our method for pose estimation for geometrically complex,occluded,symmetrical objects.We further validate our method by applying it to simulated punctures.

An Improved Algorithm for Finding the Closest Pair of Points

As early as in 1975, Shamos and Hoey first gave an O（n lg n）-time divide-and-conquer algorithm （Stt algorithm in short） for the problem of finding the closest pair of points. In one process of combination, the Euclidean distances between 3n pairs of points need to be computed, so the overall complexity of computing distance is then 3n lgn. Since the computation of distance is more costly compared with other basic operation, how to improve SH algorithm from the aspect of complexity of computing distance is considered. In 1998, Zhou, Xiong and Zhu improved SH algorithm by reducing this complexity to 2n lg n. In this paper, we make further improvement. The overall complexity of computing distances is reduced to （3n lg n）/2, which is only half that of SH algorithm.

Points of Coincidence for Weakly Compatible Pair of Mappings in Cone Metric Spaces

In this paper, some new existence and uniqueness of points of coincidence of weakly compatible pair of mappings is obtained, which does not satisfy continuity and commutativity. The conditions are weaker than the usual conditions in cone metric spaces.

3D视觉表面匹配技术在曲轴毛坯无序抓取中的应用

本文主要研究对无序排列曲轴毛坯的自动抓取,通过3D视觉技术实现空间位置搜索,并转换为机器人抓取坐标,在实际运行过程中,为解决3D算法在速度、可靠性、稳定性等方面的不足,视觉识别成功率低,机器人抓取发生碰撞的问题,利用全局模型局部匹配的算法优化基于PPF特征的投票原理,最终实现高效稳定的3D物体匹配识别,并实现了无序排列曲轴毛坯稳定、可靠、快速的抓取,满足了现实生产过程的需求。