利用梯度方向的Hausdorff 距离配准红外和可见光图像

基于Hausdorff距离的算法已经被广泛应用于异源图像配准,但是现有的Hausdorff距离配准算法是在整幅图像上找最相近的点对,不仅容易出现错误匹配的情况,而且计算量很大。为了减少计算冗余和消除误配情况,提高配准的准确度,提出了一种利用梯度方向的Hausdorff距离配准算法。在进行配准时,将提取到的角点集合按照每个角点的不同梯度方向角分解为8个子集合。然后计算两幅图像中同一方向区间所对应的两个子集合间的Hausdorff距离。由于只在对应的子集合内找最相近的配准点对,减少了干扰点的数目和计算的次数,提高了计算的有效性和异源图像配准的准确度。实验结果表明,利用梯度方向的Hausdorff距离算法能够较好地运用于红外图像和可见光图像的配准,并且表现出较好的准确度和稳健性。     

Elliptic equations with low regularity boundary data via the unified method

We use novel integral representations developed by the second author to prove certain rigorous results concerning elliptic boundary value problems in convex polygons. Central to this approach is the so-called global relation, which is a non-local equation in the Fourier space that relates the known boundary data to the unknown boundary values. Assuming that the global relation is satisfied in the weakest possible sense, i.e. in a distributional sense, we prove there exist solutions to Dirichlet, Neumann and Robin boundary value problems with distributional boundary data. We show that the analysis of the global relation characterises in a straightforward manner the possible existence of both integrable and non-integrable corner singularities.     

Error Estimates for Finite-Element Navier-Stokes Solvers without Standard Inf-Sup Conditions

The authors establish error estimates for recently developed finite-element methods for incompressible viscous flow in domains with no-slip boundary conditions. The methods arise by discretization of a well-posed extended Navier-Stokes dynamics for which pressure is determined from current velocity and force fields. The methods use C^1 elements for velocity and C^0 elements for pressure. A stability estimate is proved for a related finite-element projection method close to classical time-splitting methods of Orszag, Israeli, DeVille and Karniadakis.     

角反射器在不同条件下光学性能变化实验研究

介绍了卫星激光角反射器在激光测距中须引入直角误差来克服速差效应带来的影响,并对角反射器的远场衍射能量分布进行了实验研究。另外,分析了空气抖动和机械应力等外界因素对远场能量分布的影响。     

A novel method for generating a rectangular convex corner compensation structure in an anisotropic etching process

given to prove this new method's validity and applicability.     

3D tangentially injected swirling recirculating flow in a nozzle with a slotted‐tube—Effects of groove parameters

A numerical prediction for 3D swirling recirculating flow in an air‐jet spinning nozzle with a slotted‐tube is carried out with the realizable k–ε turbulence model. The effects of the groove parameters on the flow and yarn properties are investigated. The simulation results show that some factors, such as reverse flow upstream of the injector, vortex breakdown downstream of the injector, corner recirculation zone (CRZ) behind the step and vortex ring in the groove caused by the groove geometric variation, are significantly related to fluid flow, and consequently to yarn properties. With increasing groove height, the length of the CRZ increases, while the initial vortex ring in the groove decreases and a same direction rotating vortex forms in the bottom of the groove. Similarly, as the groove width increases, the extent of both vortex breakdown in downstream of the injectors and the vortex ring in the groove increases slightly, whereas the CRZ lengths in stream‐wise direction decrease. Some factors, such as the negative tangential velocities, the size of the vortex rings in the grooves and the CRZ, are constant for nozzles with different groove lengths. Copyright © 2009 John Wiley & Sons, Ltd.     

Multigrid methods for the computation of singular solutions and stress intensity factors I: Corner singularities

We consider the Poisson equation with homogeneous Dirichlet boundary condition on a two-dimensional polygonal domain with re-entrant angles. A multigrid method for the computation of singular solutions and stress intensity factors using piecewise linear functions is analyzed. When , the rate of convergence to the singular solution in the energy norm is shown to be , and the rate of convergence to the stress intensity factors is shown to be , where is the largest re-entrant angle of the domain and can be arbitrarily small. The cost of the algorithm is . When , the algorithm can be modified so that the convergence rate to the stress intensity factors is . In this case the maximum error of the multigrid solution over the vertices of the triangulation is shown to be .

     

微型立方反射传感器的设计与应用

介绍了采用两种技术制作的微型立方反射传感器的结构,比较它们在自由空间通信应用中的工作性能,并介绍了新型传感器的最新应用。     

The derivation of exact static conditions at the corner points for the bending of thick rectangular plates

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基于波长移相剪切干涉的准直波前重构技术

为了实现干涉仪出射准直波前的重构,提出了基于波长调谐移相的横向剪切干涉技术。干涉仪出射波前分别经楔板的前后表面反射,通过角锥棱镜返回后在干涉仪CCD上形成剪切干涉条纹。采用波长移相方法提取剪切干涉条纹的相位信息从而实现准直波前重构。分析相对剪切比对波面重构精度的影响,推导相对剪切比和其影响因素间的关系公式,给出波长移相中光程差常数分量的估算方法。测量干涉仪的三组出射波前,波前的峰谷值分别为3.22λ、2.10λ、0.83λ。该方法简化了传统测量干涉仪准直波前的横向剪切干涉装置,提高了测量精度,特别适合于测量波长移相干涉仪的出射波前。