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531.
Polarization pattern provides additional information besides spectral signatures. It can be used in many applications, such as navigation, defect detection and object identification. A novel polarization camera composed of four synchronized cameras is proposed, and it can realize real-time polarization measurement. This study particularly concentrates on the geometric calibration of the system. The projection model is analyzed and the multi-camera calibration algorithm is proposed. Firstly, each camera is calibrated separately using planar patterns, and then the geometric calibration algorithms are performed. Due to the geometrical constraint, a global optimization method results in smaller estimation uncertainties. A mean rotation error of 0.025° and a mean translation error of 0.26mm are achieved after geometric calibration. The images are rectified to establish a correspondence among cameras and are combined to acquire the polarization measurement. The polarization pattern of the skylight is measured by the system and the results are consistent with the previous studies. 相似文献
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运用车桥耦合动力理论并结合基于间接边界元法的噪声分析方法,对高速铁路32m简支槽形梁桥结构噪声的声辐射特性进行研究。结果表明:简支槽形梁的抗扭刚度小,抗扭性能弱;6.3 Hz以下频率的振动噪声主要由梁体的整体振动产生,6.3Hz以上频率的振动噪声主要由梁体构件的局部振动产生,振动噪声受构件的局部振动影响显著,声压级峰值频率为25 Hz;横桥向,随着距桥梁中线距离的增大,场点声压级逐渐变小,距离每增大5m声压级平均降低1.2~2.5dB;梁下区域距桥梁中线15m范围内,行车侧声场声压级大于非行车侧,10m处行车侧场点声压级平均大1.87dB,距桥梁中线25m范围以外,行车侧声场声压级小于非行车侧,30m处行车侧场点声压级平均小1.46dB;底板的声压贡献系数要比腹板和翼板大的多,远场声压主要受底板的影响;地面附近的噪声基本由底板产生;应当有针对性的采取措施改善结构的振动噪声性能。 相似文献
534.
Numerical analysis of the hydroelastic behavior of a vertical plate due to solitary waves 总被引:1,自引:0,他引:1
Interactions of a vertical elastic plate with fully nonlinear water waves were simulated. Utilizing the mixed Eulerian Lagrangian method for the free-surface flow and the finite element method for the deflection of an elastic plate, a fully coupled scheme for accurately determining fluid–plate motions was developed. Using this scheme, some modifications to the solvers for both fluid and plate were made. A hybrid wave-absorbing beach was installed to prevent wave reflection from the end of the wave tank. A fourth-order Runge–Kutta time-marching scheme with a uniform time step was applied to achieve numerical stability. The method was validated by simulating the wave generated by the initial deformation of a vertical plate and comparing the result with the corresponding analytical solution. For further validation, the hydroelastic behavior of a vertical plate induced by a pulse-type wave (where the initial pulse-type elevation of the free surface is specified) was computed, and the result was compared with another numerical result from a mode-expansion method. The interaction of a surface-piercing plate with nonzero initial free surface was then simulated, and the result was compared with the corresponding linear analytical solution. Finally, the hydroelastic response of a surface-piercing vertical plate due to a solitary wave (generated by actuating the vertical plate at the right end of the tank only at the beginning) was computed and investigated systematically. 相似文献
535.
何磊 《铁道标准设计通讯》2007,(4):65-66
结合石太客运专线南梁隧道出口段施工,介绍双隧并行通风技术,利用双隧并行的有利条件,一条隧道做进风口,相邻一条隧道做出风口,缩短通风长度,加快洞内污浊空气的排出,大大改善洞内施工条件,加快工程进度。 相似文献
536.
在高铁开通后虹吸效应的演变作用机理分析基础上,通过引力模型和空间计量模型,运用“有无对比法”测算江西省11个地级市与邻省主要城市之间的空间相互作用及虹吸效应强度,再将可达性与其进行空间计量分析.研究表明:高铁压缩了城市时空距离,加强了江西与邻省主要城市尤其是上海、长沙和武汉的空间相互作用;高铁使得虹吸效应作用强度的空间... 相似文献
537.
何玲 《辽宁省交通高等专科学校学报》2006,8(4):69-70
完善的内部会计控制制度能提高会计资料的正确性和可靠性;能够保护财产物资的安全完整;能够保证国家对企业的宏观控制;能够保证企业高效率经营。而企业内部会计控制原则以及相应的控制制度,能从源头和制度上治理腐败、防范风险、遏制和打击经济犯罪行为,促进市场经济的健康发展。 相似文献
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