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Electrical and mechanical properties of high-strength strain-hardening cementitious composites containing silvered polyethylene fibers
No full textTo develop multifunctional fibers for high-strength strain-hardening cementitious composites (HS-SHCC), a silver-plating technique that incorporated fibers with various pre-treatment methods using dopamine and plasma was adopted for polyethylene (PE) fibers. The effect of this plating technique on the mechanical and electrical properties of HS-SHCC was evaluated. For this, the HS-SHCC mixture with a high compressive strength of 84.1 MPa and tensile strength and strain capacity of 12.7 MPa and 8.27% was first developed. Dopamine-activated, silvered PE fiber was most effective on electroless silver plating and decreased bulk resistance of HS-SHCC by approximately 15%, potentially applicable to pavement deicing, self-sensing, electromagnetic interference shielding, etc. The PE fiber was not directly coated by the silver plating without pretreatment, and the plasma-treated fiber provided an intermediate silver coating efficiency. The silver nanoparticles deposited on the surface of the PE fibers minimally affected the compressive strength of HS-SHCC in the range of -9% to +3% but deteriorated the tensile performance in general. The mixtures with plasma or hybrid treated silvered PE fibers provided similar tensile strengths of approximately 12 MPa to the control mixture. The silvered PE fiber with dopamine pre-treatment resulted in approximately 12% and 24% lower tensile strength and strain capacity (approximately 11.2 MPa and 6.28%, respectively) compared with the plain PE fiber; however, these tensile properties are still sufficiently outstanding, relative to other HS-SHCC types available
Robust and Efficient Estimation of Relative Pose for Cameras on Selfie Sticks
No full textTaking selfies has become one of the major photographic trends of our time. In this study, we focus on the selfie stick, on which a camera is mounted to take selfies. We observe that a camera on a selfie stick typically travels through a particular type of trajectory around a sphere. Based on this finding, we propose a robust, efficient, and optimal estimation method for relative camera pose between two images captured by a camera mounted on a selfie stick. We exploit the special geometric structure of camera motion constrained by a selfie stick and define this motion as spherical joint motion. Utilizing a novel parametrization and calibration scheme, we demonstrate that the pose estimation problem can be reduced to a 3-degrees of freedom (DoF) search problem, instead of a generic 6-DoF problem. This facilitates the derivation of an efficient branch-and-bound optimization method that guarantees a global optimal solution, even in the presence of outliers. Furthermore, as a simplified case of spherical joint motion, we introduce selfie motion, which has a fewer number of DoF than spherical joint motion. We validate the performance and optimality of our method on both synthetic and real-world data. Additionally, we demonstrate the applicability of the proposed method for two applications: refocusing and stylization