基于虚拟三面体的摄像机与二维激光测距仪外参数最小解标定新算法

摄像机与激光测距仪(Camera and laser rangefinder,LRF)被广泛应用于机器人、移动道路测量车、无人驾驶等领域.其中,外参数标定是实现图像与LIDAR数据融合的第一步,也是至关重要的一步.本文提出一种新的基于最小解(Minimal solution)外参数标定算法,即摄像机与激光仅需对标定棋盘格采集三次数据.本文首次提出虚拟三面体概念,并以之构造透视三点问题(Perspective-three-point,P3P)用以计算激光与摄像机之间的坐标转换关系.相对于文献在对偶三维空间(Dual 3D space)中构造的P3P问题,本文直接在原始三维空间中构造P3P问题,具有更直观的几何意义,更利于对P3P问题进行求解与分析.针对P3P问题多达八组解的问题,本文还首次提出一种平面物成像区域约束方法从多解中获取真解,使得最小解标定法具有更大的实用性与灵活性.实验中分别利用模拟数据与真实数据对算法进行测试.算法结果表明,在同等输入的条件下,本文算法性能超过文献中的算法.本文所提的平面物成像区域约束方法能从多解中计算出真解,大大提高了最小解算法的实用性与灵活性.

基于回转车削的三面体加工运动学及误差分析

对回转车削三面体的过程进行了运动学分析,建立了刀尖相对于工件的运动方程,计算了用该方法加工三面体零件时的各个参数。在此基础上讨论了回转车削三面体时,工件存在着一定的加工误差,并且得出了加工误差的大小与刀具长度成反比,与工件直径成正比。提出了减小加工误差的方法。

双曲镜面的三面体反射器的特性分析

目的 研究角度测量中反射体的特性 .方法 几何光学方法 .结果 得到了图象坐标的表达式 .结论 在角度测量中 ,具有双曲镜面的三面体反射器的特性优于其他三面体反射器 .

GTT NO.96货舱围护系统殷瓦三面体手工焊接工艺研究与质量控制

GTTNO.96型LNG液货舱的横向环区域殷瓦(INVAR)预制件装焊是整王个货舱围护系统(Cargo Containment System)生产中重要一环,它也是围护系统生产的技术难点和瓶颈之一。横向环区域中殷瓦三面体及带材的装焊工作很复杂也很重要,焊接质量的好坏直接影响到后续工作的开展。由于整个区域生产过程复杂,上下道工序交接多,生产总周期长,因此有必要对三面体及带材与锚固扁钢焊接工艺进行研究以提高施工效率和质量。本文介绍了对殷瓦三面体及带材的焊接工艺的研究,阐述了三面体及带材与锚固扁钢焊接中存在的焊接难点及解决方法,完善、固化有关焊接工艺,从而大幅减少焊接缺陷、提高货舱围护系统的建造质量,并提高该型LNG船货舱建造效率。

浅谈独立柱三面体广告牌设计和施工要点

本文探讨了独立柱三面体钢结构广告牌设计和施工的一些特点,对进一步改进和完善这一新型建筑物具有一定的参考价值。

提高殷瓦三面体的焊接质量

为提高LNG首制船液货舱系统殷瓦预制件——三面体产品的焊接质量，特种管车间殷瓦电焊班QC小组就该课题开展QC活动，并成功使产品一次提交合格率达100％。本文对此作了简要介绍。

三维激光雷达-相机间外参的高效标定方法

在自动驾驶、移动机器人等领域,激光雷达与相机是常用的传感器,融合这两者的信息首先应该标定两者间的外参。本文在考虑平面移动机器人运动特点的基础上提出两阶段外参标定方法,在尽可能少的人为干预下实现快速标定。第一阶段,在机器人运动过程中同时估算激光里程计和视觉里程计,提取平移、旋转两种运动信息以修改的Kabsch算法初步估计外参中的旋转矩阵;第二阶段,以箱体三面相交组成的三面体作为标识物,优化点云中三面体边的投影点和图像中对应三面体边的距离,从而得到精确的外参。此两阶段方法效率高、无需专业设备,在少量人工干预下即可实现外参标定。最后,实验结果表明,在3个坐标轴上的平均误差仅为3.67、1.11、0.78 mm,在典型移动计算平台上相应的平均标定时间仅需约635 ms。

超高速摄影中铍转镜静力学与动力学性能分析

基于弹性力学空间问题基本方程、线性振动系统运动方程及有限元法,提出转镜力学特性的数值分析方法.运用该方法得出转镜镜面变形量、内部应力分布和振动模态参量的定量数值:在边缘线速度600m/s下,三面体铍转镜的最大变形量为约0.3346μm;最大应力0.204GPa,位于轴孔附近并与镜面距离最短处;两个在互相垂直平面内的一阶弯曲振动模态发生在3.4×105r/min附近,一阶扭振点位于5.13×105r/min附近,两个二阶弯曲振动点位于6.6×105r/min附近.结果表明,如制造无缺陷,由体力产生的静载荷不足以破坏镜体,对转镜产生较大破坏作用的是共振导致的疲劳破坏.

斜角坐标系组合图型的研究（二）

斜角坐标系组合图型的研究（二）谷宝庆，胡文亮，张军海，韩宪生（河北师范大学０５００１６）（河北省科学院０５００５１）本文是“斜角坐标系组合图型的研究（一）”（《地图》１９９４第４期）的续篇，主要包括斜角坐标系的三面组合与反转组合等，即斜角坐标系重组合...

例题巧合引起的正负面效应及其反思

从微分几何教材中一道例题的巧合解法引起多数初学者模仿做题时产生的负面效应,剖析了产生这种负迁移和思维定势副作用的根源,并提出避免产生此类副作用的措施,同时给出了一种更易操作的程序化解法.另一方面,从探讨数学学习的本质和学习的正负迁移角度,肯定了这类例题的巧妙构思以及给学习者带来的积极正面影响.

光的折射与反射

TH703 2002020839双曲镜面的三面体反射器的特性分析=Characteristicanalysis of trihedron reflectors with a hyperbo -loidal mirror[刊,中]/张记龙(华北工学院电子信息工程系.山西,太原(030051)),黄京生(太原市邮政局计算中心.山西,太原(030001))

Facial pain induces the alteration of transient receptor potential vanilloid receptor 1 expression in rat trigeminal ganglion

Objective To investigate the involvement of transient receptor potential vanilloid receptor 1 （TRPV1） in the facial inflammatory pain in relation to thermal hyperalgesia and cold pain sensation. Methods Facial inflammatory pain model was developed by subcutaneous injection of turpentine oil （TO） into rat facial area. Head withdrawal thermal latency （HWTL） and head withdrawal cold latency （HWCL） were measured once a day for 21 d after TO treatment using thermal and cold measurement apparatus. The immunohistochemical staining, cell-size frequency analysis and the survey of average optical density （OD） value were used to observe the changes of TRPV1 expression in the neurons of the trigeminal ganglion （TG）, peripheral nerve fibers in the vibrissal pad, and central projection processes in the trigeminal sensory nuclei caudalis （Vc） on day 3, 5, 7, 14, and 21 after TO injection. Results HWTL and HWCL decreased significantly from day 1 to day 14 after TO injection with the lowest value on day 5 and day 3, respectively, and both recovered on day 21. The number of TRPV1-labeled neurons increased remarkably from day 1 to day 14 with a peak on day 7, and returned back to the normal level on day 21. In control rats, only small and medium-sized TG neurons were immunoreactive （IR） to TRPV1, and the TRPV1-IR terminals were abundant in both the vibrissal pad and the Vc. Within 2 weeks of inflammation, the expression of TRPV1 in small and medium-sized TG neurons increased obviously. Also the TRPV1 stained terminals and fibers appeared more frequent and denser in both the vibrissal pad skin and throughout laminae Ⅰ and the outer zone of laminae Ⅱ （Ⅱo） of Vc. Conclusion Facial inflammatory pain could induce hyperalgesia to noxious heat and cold stimuli, and result in increase of the numbers of TRPV1 positive TG neurons and the peripheral and central terminals of TG. These results suggest that the phenotypic changes of TRPV1 expression in small and medium-sized TG neurons and terminals might play an important role in the development and maintenance of TO-induced inflammatory thermal hyperalgesia and cold pain sensation.

Multipartite Entanglement of a Tetrahedron Lattice

Three-dimensional Heisenberg model in the form of a tetrahedron lattice is investigated. The concurrence and multipartite entanglement are calculated through 2-concurrence C and 4-concurrence C4. The concurrence C and multipartite entanglement G4 depend on different coupling strengths Ji and are decreased when the temperature T is increased. For a symmetric tetrahedron lattice, the concurrence C is symmetric about J1 when J~ is negative while the multipartite entanglement G4 is symmetric about J1 when J2 〈 2. For a regular tetrahedron lattice, the concurrence G of ground state is 1/3 for ferromagnetic case while G = 0 for antiferromagnetic ca.se. However, there is no multipartitc entanglement since C4=0 in a regular tetrahedron lattice. The external magnetic field 13 can increase the maximum value of the concurrence GB and induce two or three peaks in Cn. There is a peak in the multipartite entanglement G4 B when G4B is varied as a function of the temperature T. This peak is mainly induced by the magnetic field B.

Effect of Gd_(0.2)Ce_(0.8)O_(1.9) nanoparticles on the oxygen evolution reaction of La_(0.6)Sr_(0.4)Co_(0.2)Fe_(0.8)O_(3-δ) anode in solid oxide electrolysis cell

La（0.6）Sr（0.4）Co（0.2）Fe（0.8）O（3-δ）（LSCF） anodes were infiltrated by Gd（0.2）Ce（0.8）O（1.9）GDC） nanoparticles to improve the oxygen evolution reaction（OER） performance of solid oxide electrolysis cells（SOECs） in CO2 electroreduction. The effect of GDC loading was investigated, and 10 wt% GDC nanoparticle infiltration of the LSCF（10 GDC/LSCF） anode results in the highest OER performance. Electrochemical impedance spectra measurements indicate that the infiltration by GDC nanoparticles greatly decreases the polarization resistance of the SOECs with the 10 GDC/LSCF anodes. The following distribution of relaxation time analysis suggests that four individual electrode processes are involved in the OER and that all of them are accelerated on the 10 GDC/LSCF anode. Three phase boundaries, surface oxygen vacancies, and bulk oxygen mobility increased, based on scanning electron microscopy and temperature-programmed desorption of O2 characterizations, and contributed to the enhancement of the four electrode processes of the OER and electrochemical performance of SOECs.

Three-dimensional Reconstruction of Geological Solids Based on Section Topology Reasoning

In order to solve the dynamic reconstruction and local updating problem of three-dimensional geological solids, topology reasoning is used for three-dimensional geological modeling. This can advance the level of the corresponding section automation in implementing the 3D geological solid dynamical reconstruction by the construction of and reasoning on topology on the 3D curved surface. This method has been successfully used in the Nanjing city geological modeling and the Zijin gold mine modeling. The results prove that this method adapts to coplanar section and noncoplanar section data, and improves the efficiency of 3D geological modeling.

Pt supported on octahedral Fe_3O_4 microcrystals as a catalyst for removal of formaldehyde under ambient conditions

Several catalysts comprising Pt supported on octahedral Fe3O4（Pt/Fe3O4） were prepared by a facile method involving co-precipitation followed by thermal treatment at different temperatures. A variety of characterization results revealed that this preparation process afforded highly crystalline octahedral Fe3O4 with a uniform distribution of Pt nanoparticles on its surface. The thermal-treatment temperature significantly influenced the redox properties of the Pt/Fe3O4 catalysts. All the Pt/Fe3O4 catalysts were found to be catalytically active and stable for the oxidation of low-concentration formaldehyde（HCHO） with oxygen. The catalyst prepared by thermal treatment at 80 °C（labelled Pt/Fe3O4-80） exhibited the highest catalytic activity, efficiently converting HCHO to CO2 and H2 O under ambient temperature and moisture conditions. The excellent performance of Pt/Fe3O4-80 was mainly attributed to beneficial interactions between the Pt and Fe species that result in the formation a higher density of active interface sites（e.g., Pt-O-FeO x and Pt-OH-FeO x）. The introduction of water vapor improves the catalytic activity of the Pt/Fe3O4 catalysts as it participates in a water-assisted dissociation process.

Numerical Simulation of Interaction Between Laminar Flow and Elastic Sheet

A numerical simulation of the interaction between laminar flow with low Reynolds number and a highly flexible elastic sheet is presented. The mathematical model for the simulation includes a three-dimensional finitevolume based fluid solver for incompressible viscous flow and a combined finite-discrete element method for the three-dimensional deformation of solid. An immersed boundary method is used to couple the simulation of fluid and solid. It is implemented through a set of immersed boundary points scattered on the solid surface. These points provide a deformable solid wall boundary for the fluid by adding body force to Navier-Stokes equations. The force from the fluid is also obtained for each point and then applied on the boundary nodes of the solid. The vortex-induced vibration of the highly flexible elastic sheet is simulated with the established mathematical model. The simulated results for both swing pattern and oscillation frequency of the elastic sheet in low Reynolds number flow agree well with experimental data.

Mechanical properties of 3D carbon/carbon composites by nanoindentation technique

Nanoindentation tests were conducted to investigate the near-surface mechanical properties of the individual components(fiber and matrix) for three-dimensional reinforced carbon/carbon composites(3D C/C).Optical microscope and polarizing light microscope were used to characterize the microstructure of 3D C/C.The microscopy results show that large number of pores and cracks exist at both bundle/matrix interface and pitch carbon matrix.These defects have important effect on the mechanical behavior of 3D C/C.The in situ properties for components of 3D C/C were acquired by nanoindentation technique.Relative to the matrix sample,the fiber samples have more larger values for modulus,stiffness and hardness.However,there is no significant difference of modulus and stiffness among fiber samples with different directions.

Microscopic Three-Body Force Effect on Nucleon-Nucleon Cross Sections in Symmetric Nuclear Matter

We provide a microscopic calculation of neutron-proton and proton-proton cross sections in symmetric nuclear matter at various densities, using the Brueckner Hartree-Fock approximation scheme with the Argonne Va4 potential including the contribution of microscopic three-body force. We investigate separately the effects of three-body force on the effective mass and on the scattering amplitude. In the present calculation, the rearrangement contribution of three-body force is considered, which will reduce the neutron and proton effective mass, and depress the amplitude of cross section. The effect of three body force is shown to be repulsive, especially in high densities and large momenta, which will suppress the cross section markedly.