The Experts below are selected from a list of 51609 Experts worldwide ranked by ideXlab platform
Joseph L Demer - One of the best experts on this subject based on the ideXlab platform.
-
the globe s eccentric Rotational axis why medial rectus surgery is more potent than lateral rectus surgery
Ophthalmology, 2018Co-Authors: Robert A Clark, Joseph L DemerAbstract:Purpose Tables typically recommend greater lateral rectus (LR) than medial rectus (MR) surgical doses for horizontal strabismus of any given magnitude, a difference unexplained by mechanical models that assume globe rotation about its center. We tested this assumption during horizontal ductions. Design Prospective observational study. Participants Eighteen adult subjects with normal binocular vision. Methods Surface coil magnetic resonance imaging at 390 or 430 μm resolution was obtained using 2-mm–thick contiguous axial planes while subjects fixated targets in central, right, and left gaze. Angular displacements of lines connecting the corneal apex through the minor lens axis to the retina were measured to approximate clinical ductions. Globe centers were calculated from their area centroids. Apparent lens and globe-optic nerve (ON) junction rotations around the globe center were then compared with clinical ductions. Main Outcome Measures Apparent angular rotations of lenses and globe-ON junctions during horizontal ductions. Results Globe-ON junctions appeared to rotate significantly less around globe centers than did lenses for abduction (20.6°±4.7° vs. 27.4°±7.4°, ± standard deviation (SD), P 0.001) and adduction (25.3°±6.7° vs. 31.9°±8.3°, P 0.001). Both rotations differed significantly from clinical adduction (27.9°±8.3°, P 0.007), but only in abduction was globe-ON junction rotation significantly less than clinical abduction (28.6°±9.4°, P 0.001). The true geometric globe Rotational center was 2.2±0.5 mm medial and 0.8±1.0 mm posterior to the geometric globe center and was displaced farther medially and posteriorly during adduction. This eccentricity imbues each millimeter of MR recession with approximately 30% more trigonometric Rotational Effect than equivalent LR recession. Conclusions The medial and posterior eccentricities of the normal ocular Rotational axis profoundly influence horizontal rectus action. The proximity of the globe's Rotational axis to the MR shortens its lever arm relative to the LR, explaining why mechanical Effects of smaller MR recessions are equivalent to larger LR recessions.
Robert A Clark - One of the best experts on this subject based on the ideXlab platform.
-
the globe s eccentric Rotational axis why medial rectus surgery is more potent than lateral rectus surgery
Ophthalmology, 2018Co-Authors: Robert A Clark, Joseph L DemerAbstract:Purpose Tables typically recommend greater lateral rectus (LR) than medial rectus (MR) surgical doses for horizontal strabismus of any given magnitude, a difference unexplained by mechanical models that assume globe rotation about its center. We tested this assumption during horizontal ductions. Design Prospective observational study. Participants Eighteen adult subjects with normal binocular vision. Methods Surface coil magnetic resonance imaging at 390 or 430 μm resolution was obtained using 2-mm–thick contiguous axial planes while subjects fixated targets in central, right, and left gaze. Angular displacements of lines connecting the corneal apex through the minor lens axis to the retina were measured to approximate clinical ductions. Globe centers were calculated from their area centroids. Apparent lens and globe-optic nerve (ON) junction rotations around the globe center were then compared with clinical ductions. Main Outcome Measures Apparent angular rotations of lenses and globe-ON junctions during horizontal ductions. Results Globe-ON junctions appeared to rotate significantly less around globe centers than did lenses for abduction (20.6°±4.7° vs. 27.4°±7.4°, ± standard deviation (SD), P 0.001) and adduction (25.3°±6.7° vs. 31.9°±8.3°, P 0.001). Both rotations differed significantly from clinical adduction (27.9°±8.3°, P 0.007), but only in abduction was globe-ON junction rotation significantly less than clinical abduction (28.6°±9.4°, P 0.001). The true geometric globe Rotational center was 2.2±0.5 mm medial and 0.8±1.0 mm posterior to the geometric globe center and was displaced farther medially and posteriorly during adduction. This eccentricity imbues each millimeter of MR recession with approximately 30% more trigonometric Rotational Effect than equivalent LR recession. Conclusions The medial and posterior eccentricities of the normal ocular Rotational axis profoundly influence horizontal rectus action. The proximity of the globe's Rotational axis to the MR shortens its lever arm relative to the LR, explaining why mechanical Effects of smaller MR recessions are equivalent to larger LR recessions.
Salem Ostaoma - One of the best experts on this subject based on the ideXlab platform.
-
new vortex lift and tangential force models for hawt aerodynamic load prediction
Wind Energy, 2020Co-Authors: Moutaz Elgammi, G Schepers, Salem OstaomaAbstract:Horizontal axis wind turbines (HAWTs) experience three-dimensional Rotational and unsteady aerodynamic phenomena at the rotor blades sections. These highly unsteady three-dimensional Effects have a dramatic impact on the aerodynamic load distributions on the blades, in particular, when they occur at high angles of attack due to stall delay and dynamic stall. Unfortunately, there is no complete understanding of the flow physics yet at these unsteady 3D flow conditions, and hence, the existing published theoretical models are often incapable of modelling the impact on the turbine response realistically. The purpose of this paper is to provide an insight on the combined influence of the stall delay and dynamic stall on the blade load history of wind turbines in controlled and uncontrolled conditions. New dynamic stall vortex and nonlinear tangential force coefficient modules, which integrally take into account the three dimensional Rotational Effect, are also proposed in this paper. This module along with the unsteady influence of turbulent wind speed and tower shadow is implemented in a blade element momentum (BEM) model to estimate the aerodynamic loads on a rotating blade more accurately. This work presents an important step to help modelling the combined influence of the stall delay and dynamic stall on the load history of the rotating wind turbine blades which is vital to have lighter turbine blades and improved wind turbine design systems.
Preston Guynn - One of the best experts on this subject based on the ideXlab platform.
-
Thomas Precession is the Basis for the Structure of Matter and Space
2018Co-Authors: Preston GuynnAbstract:Einstein's theory of special relativity was incomplete as originally formulated since it did not include the Rotational Effect described twenty years later by Thomas, now referred to as Thomas precession. Though Thomas precession has been accepted for decades, its relationship to particle structure is a recent discovery, first described in an article titled "Electromagnetic Effects and structure of particles due to special relativity". Thomas precession acts as a velocity dependent counter-rotation, so that at a rotation velocity of SQRT(3)/2 c, the magnitude of precession is equal to the magnitude of rotation, resulting in an inertial frame of reference. During the last year and a half significant progress was made in determining further details of the role of Thomas precession in particle structure, fundamental constants, and the galactic rotation velocity. In this article, these discoveries are described and proofs are provided, with results matching experimentally determined values to between eight and thirteen significant digits. Among the discoveries described and proven herein are 1) the observed galactic rotation velocity and elementary particle spin interact due to Thomas precession, 2) the basis for Planck's constant and quantized energy levels is Thomas precession, 3) the fine structure constant is a function of galactic rotation velocity and the maximum value of rotation velocity minus precession velocity. Also discovered and proven is that, due to the inertial frame of reference resulting from Thomas precession, distance and time, with units meters and seconds, within three dimensional space are sufficient to describe the structure of particles and their interactions. Einstein showed that energy is dependent on frame of reference with his equation E =γ mc^2 , and he formulated E = mc^2 as rest energy. Proven herein is that particle mass and rest energy are functions of Rotational velocity due to Thomas precession. These far reaching discoveries are all interrelated, and based in Thomas precession. The theory, models, and equations give results that match experimental data to very high precision.
-
Thomas Precession is the Basis for the Structure of Matter and Space
viXra, 2018Co-Authors: Preston GuynnAbstract:Einstein's theory of special relativity was incomplete as originally formulated since it did not include the Rotational Effect described twenty years later by Thomas, now referred to as Thomas precession. Though Thomas precession has been accepted for decades, its relationship to particle structure is a recent discovery, first described in an article titled "Electromagnetic Effects and structure of particles due to special relativity". Thomas precession acts as a velocity dependent counter-rotation, so that at a rotation velocity of (Sqr(3)/2) c, precession is equal to rotation, resulting in an inertial frame of reference. During the last year and a half significant progress was made in determining further details of the role of Thomas precession in particle structure, fundamental constants, and the galactic rotation velocity. In this article, these discoveries are described and proofs are provided, with results matching experimentally determined values to between eight and thirteen significant digits. Among the discoveries described and proven herein are 1) the observed galactic rotation velocity and elementary particle spin interact due to Thomas precession, 2) the basis for Planck's constant and quantized energy levels is Thomas precession, 3) the fine structure constant is a function of galactic rotation velocity and the maximum value of rotation velocity minus precession velocity. Also discovered and proven is that, due to the inertial frame of reference resulting from Thomas precession, distance and time, with units meters and seconds, within three dimensional space are sufficient to describe the structure of particles and their interactions. Einstein showed that energy is dependent on frame of reference with his equation E =g mc2, and he formulated E = mc2 as rest energy. Proven herein is that particle mass and rest energy are functions of Rotational velocity due to Thomas precession. These far reaching discoveries are all interrelated, and based in Thomas precession. The theory, models, and equations give results that match experimental data to very high precision.
J F Cao - One of the best experts on this subject based on the ideXlab platform.
-
unsteady aerodynamic analysis for offshore floating wind turbines under different wind conditions
Philosophical Transactions of the Royal Society A, 2015Co-Authors: Tongguang Wang, Yue Yuan, J F CaoAbstract:A free-vortex wake (FVW) model is developed in this paper to analyse the unsteady aerodynamic performance of offshore floating wind turbines. A time-marching algorithm of third-order accuracy is applied in the FVW model. Owing to the complex floating platform motions, the blade inflow conditions and the positions of initial points of vortex filaments, which are different from the fixed wind turbine, are modified in the implemented model. A three-dimensional Rotational Effect model and a dynamic stall model are coupled into the FVW model to improve the aerodynamic performance prediction in the unsteady conditions. The Effects of floating platform motions in the simulation model are validated by comparison between calculation and experiment for a small-scale rigid test wind turbine coupled with a floating tension leg platform (TLP). The dynamic inflow Effect carried by the FVW method itself is confirmed and the results agree well with the experimental data of a pitching transient on another test turbine. Also, the flapping moment at the blade root in yaw on the same test turbine is calculated and compares well with the experimental data. Then, the aerodynamic performance is simulated in a yawed condition of steady wind and in an unyawed condition of turbulent wind, respectively, for a large-scale wind turbine coupled with the floating TLP motions, demonstrating obvious differences in rotor performance and blade loading from the fixed wind turbine. The non-dimensional magnitudes of loading changes due to the floating platform motions decrease from the blade root to the blade tip.
