To investigate the robustness of face recognition algorithms under the complicated variations of illumination, facial expression and posture, the advantages and disadvantages of seven typical algorithms on extracting ...To investigate the robustness of face recognition algorithms under the complicated variations of illumination, facial expression and posture, the advantages and disadvantages of seven typical algorithms on extracting global and local features are studied through the experiments respectively on the Olivetti Research Laboratory database and the other three databases （the three subsets of illumination, expression and posture that are constructed by selecting images from several existing face databases）. By taking the above experimental results into consideration, two schemes of face recognition which are based on the decision fusion of the twodimensional linear discriminant analysis （2DLDA） and local binary pattern （LBP） are proposed in this paper to heighten the recognition rates. In addition, partitioning a face nonuniformly for its LBP histograms is conducted to improve the performance. Our experimental results have shown the complementarities of the two kinds of features, the 2DLDA and LBP, and have verified the effectiveness of the proposed fusion algorithms.展开更多
Segmental lining structures constructed by shields/tunnel boring machines are often subjected to uneven longitudinal cross-section torsion as a result of eccentric external loads,which is extremely adverse to tunnel s...Segmental lining structures constructed by shields/tunnel boring machines are often subjected to uneven longitudinal cross-section torsion as a result of eccentric external loads,which is extremely adverse to tunnel safety but has not received sufficient attention for a long time.To figure out the torsional performance of segmental tunnels,it is essential to assess the longitudinal torsional stiffness and active-torsion-rejection capability of a segmented tunnel.The aim of the paper is to derive an analytical solution to the longitudinal torsional stiffness of a segmental tunnel with existing elliptical deformation.The longitudinal torsional stiffness under different internal force combinations is deduced considering the longitudinal axial force and bending moment based on the equivalent continuous model and force balance equation.The validity of the analytical solution is verified by comparing it with finite element method results.Then,a parametric analysis,using the new analytical solution,is included to investigate the effect of the key parameters on torsional behaviors,including the segment size,the bolt size and the transverse bending stiffness,etc.It is found that:(1)the longitudinal torsional stiffness efficiency(LTSE)of the segmental tunnel decreases with the rise of segment thickness to diameter ratio but increases with the ring width to diameter ratio;(2)the LTSE reduces with the increase of the effective shear length but rises with the diameter of bolts;(3)the LTSE increases rapidly with the ratio of compression-torsion or bending-torsion.Furthermore,the envelope curve of the critical load(N0,M0)for a tunnel to actively resist a certain internal torque is given.The proposed solution can be easily utilized to determine the longitudinal torsional stiffness of segmental tunnels and is an effective tool for tunnel design and maintenance.展开更多
文摘To investigate the robustness of face recognition algorithms under the complicated variations of illumination, facial expression and posture, the advantages and disadvantages of seven typical algorithms on extracting global and local features are studied through the experiments respectively on the Olivetti Research Laboratory database and the other three databases （the three subsets of illumination, expression and posture that are constructed by selecting images from several existing face databases）. By taking the above experimental results into consideration, two schemes of face recognition which are based on the decision fusion of the twodimensional linear discriminant analysis （2DLDA） and local binary pattern （LBP） are proposed in this paper to heighten the recognition rates. In addition, partitioning a face nonuniformly for its LBP histograms is conducted to improve the performance. Our experimental results have shown the complementarities of the two kinds of features, the 2DLDA and LBP, and have verified the effectiveness of the proposed fusion algorithms.
基金support of the National Natural Science Foundation of China(Grant No.52090082)the Fundamental Research Funds for the Central Universities of China(Grant No.22120210428).
文摘Segmental lining structures constructed by shields/tunnel boring machines are often subjected to uneven longitudinal cross-section torsion as a result of eccentric external loads,which is extremely adverse to tunnel safety but has not received sufficient attention for a long time.To figure out the torsional performance of segmental tunnels,it is essential to assess the longitudinal torsional stiffness and active-torsion-rejection capability of a segmented tunnel.The aim of the paper is to derive an analytical solution to the longitudinal torsional stiffness of a segmental tunnel with existing elliptical deformation.The longitudinal torsional stiffness under different internal force combinations is deduced considering the longitudinal axial force and bending moment based on the equivalent continuous model and force balance equation.The validity of the analytical solution is verified by comparing it with finite element method results.Then,a parametric analysis,using the new analytical solution,is included to investigate the effect of the key parameters on torsional behaviors,including the segment size,the bolt size and the transverse bending stiffness,etc.It is found that:(1)the longitudinal torsional stiffness efficiency(LTSE)of the segmental tunnel decreases with the rise of segment thickness to diameter ratio but increases with the ring width to diameter ratio;(2)the LTSE reduces with the increase of the effective shear length but rises with the diameter of bolts;(3)the LTSE increases rapidly with the ratio of compression-torsion or bending-torsion.Furthermore,the envelope curve of the critical load(N0,M0)for a tunnel to actively resist a certain internal torque is given.The proposed solution can be easily utilized to determine the longitudinal torsional stiffness of segmental tunnels and is an effective tool for tunnel design and maintenance.
