针对海上低纹理、大视差图像拼接过程中由于误对齐产生的伪影问题,提出一种基于点线特征配准和最佳接缝线融合的几何结构保视差图像拼接算法。在传统的基于点特征求解单应变换的基础上引入线段特征,并将潜在的共面局部线段合并为全局线...针对海上低纹理、大视差图像拼接过程中由于误对齐产生的伪影问题,提出一种基于点线特征配准和最佳接缝线融合的几何结构保视差图像拼接算法。在传统的基于点特征求解单应变换的基础上引入线段特征,并将潜在的共面局部线段合并为全局线段,为接缝线融合提供精准对齐的条件;在图像融合过程中,利用tanh度量的颜色差异和梯度差异以及引入显著性检测权重来设计接缝切割方法的能量函数,引导最佳接缝线避开图像中显著海上结构,从而确保结构边缘的连续性;使用SIFT flow方法校正拼接缝上的错位像素,实现几何结构准确的海上图像拼接。在20对不同场景数据上的拼接实验表明,与基准方法相比,所提算法的基于SSIM的接缝质量误差平均降低了44.6%,最多降低66.7%,基于ZNCC(zero mean normalized cross-correlation)的接缝质量误差平均降低了24.7%,最多降低了51.6%,能够有效地避免伪影,从而得到观感自然的拼接结果,满足无人船航行过程中对宽视场的需求。展开更多
The flatwise tension(FWT) and single leg bending(SLB) tests were used to investigate the fracture behavior of honeycomb sandwich specimens.In the FWT test,only the interlaminar delamination was observed.The test resul...The flatwise tension(FWT) and single leg bending(SLB) tests were used to investigate the fracture behavior of honeycomb sandwich specimens.In the FWT test,only the interlaminar delamination was observed.The test results show that the interfacial peel strength is higher than the interlaminar peel strength.In terms of SLB experiment,a new fracture mode was found,namely IKP(initiation of interlaminar delamination,kinking into facesheet and propagation of interlaminar delamination).The virtual crack closure technique was applied to separate the values of Mode I and Mode II components of the strain energy release rate in SLB experiment.The finite element analysis result shows that the Mode I strain energy release rate is higher than the Mode II strain energy release rate.To simulate the failure of SLB test of honeycomb sandwich specimens,a new computational model based on the Tsai-Hill failure criterion and the cohesive zone model is proposed.In comparison with experimental results,it can be concluded that the computational model can validly simulate the IKP of a honeycomb sandwich structures with reasonable accuracy.展开更多
Pressure is one of the important measures to control the surface accuracy of the reflector of inflatable antenna. Experiments and numerical analysis were carried out to highlight the effect of pressure on accuracy. Th...Pressure is one of the important measures to control the surface accuracy of the reflector of inflatable antenna. Experiments and numerical analysis were carried out to highlight the effect of pressure on accuracy. The rapid, contactless and low-cost digital photogrammetry system （DIES） was employed to investigate the effect according to its lightweight and flexible characteristics. Measurement data show that the best pressure and the best area in this pressure can be obtained. Numerical analysis was conducted to check the measurement result. It is indicated that there is a little difference between them attributed to wrinkle. Results of analysis and experiments show that surface accuracy of the reflector can be adjusted by controlling pressure.展开更多
The tilting-train is very attractive to the railroad users in the world due to the advantage of high speed in curved track using pre-existing infrastructure of railway.Tilting-train has a unique allowable speed and me...The tilting-train is very attractive to the railroad users in the world due to the advantage of high speed in curved track using pre-existing infrastructure of railway.Tilting-train has a unique allowable speed and mechanism especially in curved track.In this work,when tilting-train is operated with the allowable speed,the behavior of roadbed is evaluated by examining its settlement and bearing capacity.Additionally,the stability of roadbed is estimated as the roadbed is in the condition of soft soil influenced by the weather effects and cyclic train loading.Numerical results show that the roadbed settlement satisfies the allowable settlement when the elastic moduli of upper roadbed and in-situ soil are greater than 3800 and 4600 kN/m2 for rail joint and 2300 and 3300 kN/m2 for continuous welded rail(CWR).展开更多
文摘针对海上低纹理、大视差图像拼接过程中由于误对齐产生的伪影问题,提出一种基于点线特征配准和最佳接缝线融合的几何结构保视差图像拼接算法。在传统的基于点特征求解单应变换的基础上引入线段特征,并将潜在的共面局部线段合并为全局线段,为接缝线融合提供精准对齐的条件;在图像融合过程中,利用tanh度量的颜色差异和梯度差异以及引入显著性检测权重来设计接缝切割方法的能量函数,引导最佳接缝线避开图像中显著海上结构,从而确保结构边缘的连续性;使用SIFT flow方法校正拼接缝上的错位像素,实现几何结构准确的海上图像拼接。在20对不同场景数据上的拼接实验表明,与基准方法相比,所提算法的基于SSIM的接缝质量误差平均降低了44.6%,最多降低66.7%,基于ZNCC(zero mean normalized cross-correlation)的接缝质量误差平均降低了24.7%,最多降低了51.6%,能够有效地避免伪影,从而得到观感自然的拼接结果,满足无人船航行过程中对宽视场的需求。
基金Sponsored by the Heilongjiang Postdoctoral Grant and the National Science Foundation for Post-doctoral Scientists of China (Grant No.20080440887)
文摘The flatwise tension(FWT) and single leg bending(SLB) tests were used to investigate the fracture behavior of honeycomb sandwich specimens.In the FWT test,only the interlaminar delamination was observed.The test results show that the interfacial peel strength is higher than the interlaminar peel strength.In terms of SLB experiment,a new fracture mode was found,namely IKP(initiation of interlaminar delamination,kinking into facesheet and propagation of interlaminar delamination).The virtual crack closure technique was applied to separate the values of Mode I and Mode II components of the strain energy release rate in SLB experiment.The finite element analysis result shows that the Mode I strain energy release rate is higher than the Mode II strain energy release rate.To simulate the failure of SLB test of honeycomb sandwich specimens,a new computational model based on the Tsai-Hill failure criterion and the cohesive zone model is proposed.In comparison with experimental results,it can be concluded that the computational model can validly simulate the IKP of a honeycomb sandwich structures with reasonable accuracy.
文摘Pressure is one of the important measures to control the surface accuracy of the reflector of inflatable antenna. Experiments and numerical analysis were carried out to highlight the effect of pressure on accuracy. The rapid, contactless and low-cost digital photogrammetry system （DIES） was employed to investigate the effect according to its lightweight and flexible characteristics. Measurement data show that the best pressure and the best area in this pressure can be obtained. Numerical analysis was conducted to check the measurement result. It is indicated that there is a little difference between them attributed to wrinkle. Results of analysis and experiments show that surface accuracy of the reflector can be adjusted by controlling pressure.
基金supported by the 2014 Inje University research grant
文摘The tilting-train is very attractive to the railroad users in the world due to the advantage of high speed in curved track using pre-existing infrastructure of railway.Tilting-train has a unique allowable speed and mechanism especially in curved track.In this work,when tilting-train is operated with the allowable speed,the behavior of roadbed is evaluated by examining its settlement and bearing capacity.Additionally,the stability of roadbed is estimated as the roadbed is in the condition of soft soil influenced by the weather effects and cyclic train loading.Numerical results show that the roadbed settlement satisfies the allowable settlement when the elastic moduli of upper roadbed and in-situ soil are greater than 3800 and 4600 kN/m2 for rail joint and 2300 and 3300 kN/m2 for continuous welded rail(CWR).
