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Gavin M King - One of the best experts on this subject based on the ideXlab platform.
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three dimensional atomic Force microscopy interaction Force Vector by direct observation of tip trajectory
Biophysical Journal, 2014Co-Authors: Krishna P Sigdel, Justin S Grayer, Gavin M KingAbstract:The prospect of a robust three dimensional atomic Force microscope (AFM) holds significant promise in nanoscience. Yet, in conventional AFM, the tip-sample interaction Force Vector is not directly accessible. We scatter a focused laser directly off an AFM tip apex to rapidly and precisely measure the tapping tip trajectory in three dimensional space. This data also yields three dimensional cantilever spring constants, effective masses, and hence, the tip-sample interaction Force components via Newton's second law. Significant lateral Forces representing 49% and 13% of the normal Force (Fz = 152 +/- 17 pN) were observed in common tapping mode conditions as a silicon tip intermittently contacted a glass substrate in aqueous solution; as a consequence, the direction of the Force Vector tilted considerably more than expected. When addressing the surface of a lipid bilayer, the behavior of the Force components differed significantly from that observed on glass. This is attributed to the lateral mobility of the lipid membrane coupled with its elastic properties. Direct access to interaction components Fx, Fy, and Fz provides a more complete view of tip dynamics that underlie Force microscope operation and can form the foundation of a three-dimensional AFM in a plurality of conditions.
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three dimensional atomic Force microscopy interaction Force Vector by direct observation of tip trajectory
Nano Letters, 2013Co-Authors: Krishna P Sigdel, Justin S Grayer, Gavin M KingAbstract:The prospect of a robust three-dimensional atomic Force microscope (AFM) holds significant promise in nanoscience. Yet, in conventional AFM, the tip–sample interaction Force Vector is not directly accessible. We scatter a focused laser directly off an AFM tip apex to rapidly and precisely measure the tapping tip trajectory in three-dimensional space. This data also yields three-dimensional cantilever spring constants, effective masses, and hence, the tip–sample interaction Force components via Newton’s second law. Significant lateral Forces representing 49 and 13% of the normal Force (Fz = 152 ± 17 pN) were observed in common tapping mode conditions as a silicon tip intermittently contacted a glass substrate in aqueous solution; as a consequence, the direction of the Force Vector tilted considerably more than expected. When addressing the surface of a lipid bilayer, the behavior of the Force components differed significantly from that observed on glass. This is attributed to the lateral mobility of the li...
Krishna P Sigdel - One of the best experts on this subject based on the ideXlab platform.
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three dimensional atomic Force microscopy interaction Force Vector by direct observation of tip trajectory
Biophysical Journal, 2014Co-Authors: Krishna P Sigdel, Justin S Grayer, Gavin M KingAbstract:The prospect of a robust three dimensional atomic Force microscope (AFM) holds significant promise in nanoscience. Yet, in conventional AFM, the tip-sample interaction Force Vector is not directly accessible. We scatter a focused laser directly off an AFM tip apex to rapidly and precisely measure the tapping tip trajectory in three dimensional space. This data also yields three dimensional cantilever spring constants, effective masses, and hence, the tip-sample interaction Force components via Newton's second law. Significant lateral Forces representing 49% and 13% of the normal Force (Fz = 152 +/- 17 pN) were observed in common tapping mode conditions as a silicon tip intermittently contacted a glass substrate in aqueous solution; as a consequence, the direction of the Force Vector tilted considerably more than expected. When addressing the surface of a lipid bilayer, the behavior of the Force components differed significantly from that observed on glass. This is attributed to the lateral mobility of the lipid membrane coupled with its elastic properties. Direct access to interaction components Fx, Fy, and Fz provides a more complete view of tip dynamics that underlie Force microscope operation and can form the foundation of a three-dimensional AFM in a plurality of conditions.
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three dimensional atomic Force microscopy interaction Force Vector by direct observation of tip trajectory
Nano Letters, 2013Co-Authors: Krishna P Sigdel, Justin S Grayer, Gavin M KingAbstract:The prospect of a robust three-dimensional atomic Force microscope (AFM) holds significant promise in nanoscience. Yet, in conventional AFM, the tip–sample interaction Force Vector is not directly accessible. We scatter a focused laser directly off an AFM tip apex to rapidly and precisely measure the tapping tip trajectory in three-dimensional space. This data also yields three-dimensional cantilever spring constants, effective masses, and hence, the tip–sample interaction Force components via Newton’s second law. Significant lateral Forces representing 49 and 13% of the normal Force (Fz = 152 ± 17 pN) were observed in common tapping mode conditions as a silicon tip intermittently contacted a glass substrate in aqueous solution; as a consequence, the direction of the Force Vector tilted considerably more than expected. When addressing the surface of a lipid bilayer, the behavior of the Force components differed significantly from that observed on glass. This is attributed to the lateral mobility of the li...
Justin S Grayer - One of the best experts on this subject based on the ideXlab platform.
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three dimensional atomic Force microscopy interaction Force Vector by direct observation of tip trajectory
Biophysical Journal, 2014Co-Authors: Krishna P Sigdel, Justin S Grayer, Gavin M KingAbstract:The prospect of a robust three dimensional atomic Force microscope (AFM) holds significant promise in nanoscience. Yet, in conventional AFM, the tip-sample interaction Force Vector is not directly accessible. We scatter a focused laser directly off an AFM tip apex to rapidly and precisely measure the tapping tip trajectory in three dimensional space. This data also yields three dimensional cantilever spring constants, effective masses, and hence, the tip-sample interaction Force components via Newton's second law. Significant lateral Forces representing 49% and 13% of the normal Force (Fz = 152 +/- 17 pN) were observed in common tapping mode conditions as a silicon tip intermittently contacted a glass substrate in aqueous solution; as a consequence, the direction of the Force Vector tilted considerably more than expected. When addressing the surface of a lipid bilayer, the behavior of the Force components differed significantly from that observed on glass. This is attributed to the lateral mobility of the lipid membrane coupled with its elastic properties. Direct access to interaction components Fx, Fy, and Fz provides a more complete view of tip dynamics that underlie Force microscope operation and can form the foundation of a three-dimensional AFM in a plurality of conditions.
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three dimensional atomic Force microscopy interaction Force Vector by direct observation of tip trajectory
Nano Letters, 2013Co-Authors: Krishna P Sigdel, Justin S Grayer, Gavin M KingAbstract:The prospect of a robust three-dimensional atomic Force microscope (AFM) holds significant promise in nanoscience. Yet, in conventional AFM, the tip–sample interaction Force Vector is not directly accessible. We scatter a focused laser directly off an AFM tip apex to rapidly and precisely measure the tapping tip trajectory in three-dimensional space. This data also yields three-dimensional cantilever spring constants, effective masses, and hence, the tip–sample interaction Force components via Newton’s second law. Significant lateral Forces representing 49 and 13% of the normal Force (Fz = 152 ± 17 pN) were observed in common tapping mode conditions as a silicon tip intermittently contacted a glass substrate in aqueous solution; as a consequence, the direction of the Force Vector tilted considerably more than expected. When addressing the surface of a lipid bilayer, the behavior of the Force components differed significantly from that observed on glass. This is attributed to the lateral mobility of the li...
Ta-kang Yeh - One of the best experts on this subject based on the ideXlab platform.
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analytical solution of a satellite orbit disturbed by lunar and solar gravitation
Monthly Notices of the Royal Astronomical Society, 2011Co-Authors: Ta-kang Yeh, Wu ChenAbstract:In this paper, we derive to the second order (5 x 10- 6 ) the analytical solution of a satellite orbit disturbed by the lunar gravitational Force. The Force Vector is first expanded to omit terms smaller than the third order (10 -9 ). Then, four terms of potential functions are derived from the expanded Force Vector and set into the Lagrangian equations of satellite motion to obtain the theoretical solutions. For the first term of the potential functions, the solutions are derived directly. For the second term, mathematical expansions and transformations are used to separate disturbances into three parts: short-periodic terms with triangular functions of M, long-periodic terms with triangular functions of (ω, i, Ω) and secular terms with non-periodic functions of (a, e). The integrations are then carried out with respect to M, (ω, i, Ω) and t, to obtain the analytical solutions of satellite orbits with a program using mathematical symbolic operation software. The third potential function differs from the second by a factor and the fourth is simpler than the second. Therefore, the solutions are derived similarly using slightly modified programs, respectively. The results show that only two Keplerian elements (ω, M) are linearly perturbed by lunar gravitation; that is, the lunar attracting Force will cause a linear regression (delay) of the perigee (orientation of the ellipse) and a linear delay of the position (mean anomaly) on an Earth satellite. The Keplerian element a (semimajor axis of the ellipse) is not perturbed long periodically as the others. The derived solutions are also valid for solar and planetary gravitational disturbances. Because of the distance differences between the Moon, the Sun and the planets to the Earth or an Earth satellite, the solutions are of third and fourth orders for solar and planetary gravitational disturbances on an Earth satellite, respectively.
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Analytical solution of a satellite orbit disturbed by atmospheric drag
Monthly Notices of the Royal Astronomical Society, 2010Co-Authors: Xu Tianhe, Wu Chen, Ta-kang YehAbstract:In this paper, we derive the analytical solution of a satellite orbit disturbed by atmospheric drag. The disturbance Force Vector is first transformed and rotated to the orbital frame so that it can be used in the simplified Gaussian equations of satellite motion. Then, the Force Vector is expanded to triangular functions of the Keplerian angular elements and the disturbances are separated into three parts: short-periodic terms with triangular functions of M, long-periodic terms with triangular functions of (ω, i) and secular terms [non-periodic functions of (a, e)] with a program using mathematical symbolic operation software. The integrations are then carried out with respect to M, (ω, i) and t, respectively, to obtain the analytical solutions of satellite orbits disturbed by atmospheric drag. Some interesting conclusions are obtained theoretically. The atmospheric disturbance Force is not a function of Ω. The semimajor axis a of the orbital ellipse is reduced in a constant and strong manner by the air disturbance; the shape of the ellipse (eccentricity e) changes towards a more circular orbit in a linear and weak manner. The right ascension of the ascending node Ω and the mean anomaly M are influenced by the disturbance only short periodically.
Jike Liu - One of the best experts on this subject based on the ideXlab platform.
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structural damage identification based on residual Force Vector and response sensitivity analysis
Journal of Vibration and Control, 2016Co-Authors: Jike LiuAbstract:A two-stage approach based on residual Force Vector and response sensitivity analysis is proposed for structural damage identification in this study. Local damage is represented by a perturbation in the elemental stiffness parameter of the structural finite element model. Primarily, the difference between the virtual residual Force Vector of an intact and damaged structure is used to localize the damage. Then, a response sensitivity-based method is adopted to identify the perturbation of the stiffness parameter (i.e., the extent of the local damage) from the measured dynamic responses. Numerical simulations are conducted to identify both single and multiple structural damages under sinusoidal or impulsive excitation. The proposed approach gives satisfactory results with artificial measurement noise.