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Since deformation estimation may lead to errors occurring when the camera vibrates, it is necessary to remove the image global motion before computing real bridge deformation. In this study, a combination of image motion correction algorithm and 2D image-based deformation measurement technique was utilized to address the issue of camera motion during the image data acquisition for bridge deformation measurement. Based on the proposed methodology, the image motion parameters were estimated by defining an effective sub-image in the image and using Iterative Affine Motion Estimator. Then the estimated parameters were applied to all pixels of each captured image to remove the motion effect. Finally, the corrected images were used to analyze by a 2D image-based deformation measurement technique in order to extract and measure real bridge deformation by tracking artificial or natural targets. The proposed methodology was validated by two experiments in the lab and field environments. Achieved results show the accuracy and reliability of the proposed methodology. [ABSTRACT FROM AUTHOR]

Open graded friction course (OGFC) is effective in improving the surface function of asphalt pavements. However, it is prone to clogging including deformation-related and particle-related clogging. The aim of the research reported in this paper is to investigate the permeability loss or reduction due to deformation-related clogging and explore the critical size of solid particles attributed to OGFC particlerelated clogging. A special falling head permeameter was developed with consideration of both rainwater flowing procedure and the pavement transversal slope. Eight types of OGFC mixtures with different air void contents, gradations, and nominal maximum aggregate sizes were prepared for deformation-related clogging evaluation. Wheel rutting tests were conducted on the OGFC samples with different loading times under two load levels [(1) 700 kPa, and (2) 900 kPa] at 45 and 60°C, and next were permeability tests using the developed permeameter. Permeability loss after different wheel loading times were calculated to explore the effects of the initial air void content, nominal maximum aggregate size, temperature, and loading pressure on deformation-related clogging. Furthermore, seven types of suspension liquids were prepared for particle-related clogging evaluation. For each suspension liquid, the proportions of solids trapped in OGFC air void, passing OGFC sample, and retained on the sample surface were calculated after permeability tests to determine the critical sizes of particle attributed to particle-related clogging. Results show that with the increase in wheel loading times, the permeability of OGFC mixture shows a steady decrease after a sharp initial decline. Permeability loss due to deformation-related clogging can be reduced effectively by using larger nominal maximum aggregate size and larger air voids. Values of 0.15-0.3 and 1.18-2.36 mm are the critical sizes of trapped particles in OGFC mixtures. [ABSTRACT FROM AUTHOR]

During the machining of aerospace thin-walled components, a large amount material is removed, and machining-induced residual stress is induced in the boundary layer of the work piece, which results in deformation of the components. In this study, the effects of material initial residual stress and machining-induced residual stress on the deformation of aluminium alloy plate are studied. A theoretical model of the plate is analysed first, and the experiments of the milling deformation under different initial residual stress conditions are performed. The results show that the machining-induced residual stress is the primary factor of distortion. The coupling action of compressive initial residual stress and machining-induced residual stress increase the plate deformation, and the coupling action of tensile initial residual stress and machining-induced residual stress decrease the plate deformation. The finite element simulation results are compared with experimental results and found to be in good agreement. [ABSTRACT FROM AUTHOR]