Journal articles: 'Rotation motion – Dynamics'

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Misslisch, H., and D. Tweed. "Torsional dynamics and cross-coupling in the human vestibulo-ocular reflex during active head rotation." Journal of Vestibular Research 10, no. 2 (April 1, 2000): 119–25. http://dx.doi.org/10.3233/ves-2000-10207.

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Six subjects fixated an imagined space-fixed target in darkness, or a visible target against a structured visual background, while rotating their heads actively in yaw, pitch and roll at four different frequencies, from 0.3 to 2.4 Hz. We used search coils to measure the 3-dimensional rotations of the head and eye, and described the relation between them – the input-output function of the rotational vestibulo-ocular reflex (VOR) – using gain matrices. We found consistent cross-coupling in which torsional head rotation evoked horizontal eye rotation. The reason may be that the eyes are above the axis of torsional head rotation, and therefore may translate horizontally during the head motion, so the VOR rotates them horizontally to compensate. Torsional gain was lower than horizontal or vertical, more variable from subject to subject and decreased at low frequencies. One reason for the low gain may be that torsional head rotation produces little retinal slip near the fovea; hence little compensatory eye motion is needed, and so the VOR reduces its torsional gain to save energy or to approximate Listing's law by keeping ocular torsion near zero. In addition, the human VOR has little experience with purely torsional head rotations and so its adaptive networks may be poorly trained for such stimuli. The drop in torsional gain at low frequencies can be explained based on the leak in the neural integrator that helps convert torsional eye-velocity commands into eye-position commands.

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Banerjee, A. K., and M. E. Lemak. "Multi-Flexible Body Dynamics Capturing Motion-Induced Stiffness." Journal of Applied Mechanics 58, no. 3 (September 1, 1991): 766–75. http://dx.doi.org/10.1115/1.2897262.

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This paper presents a multi-flexible-body dynamics formulation incorporating a recently developed theory for capturing motion-induced stiffness for an arbitrary structure undergoing large rotation and translation accompanied by small vibrations. In essence, the method consists of correcting dynamical equations for an arbitrary flexible body, unavoidably linearized prematurely in modal coordinates, with generalized active forces due to geometric stiffness corresponding to a system of 12 inertia forces and 9 inertia couples distributed over the body. Computation of geometric stiffness in this way does not require any iterative update. Equations of motion are derived by means of Kane’s method. A treatment is given for handling prescribed motions and calculating interaction forces. Results of simulations of motions of three flexible spacecraft, involving stiffening during spinup motion, dynamic buckling, and a slewing maneuver, demonstrate the validity and generality of the theory.

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Bubenchikov, M. A., A. M. Bubenchikov, and D. V. Mamontov. "ROTATIONS AND VIBRATIONS OF FULLERENES IN THE MOLECULAR COMPLEX C20@C80." Vestnik Tomskogo gosudarstvennogo universiteta. Matematika i mekhanika, no. 71 (2021): 35–48. http://dx.doi.org/10.17223/19988621/71/4.

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The aim of this work is to apply classical mechanics to a description of the dynamic state of C20@C80 diamond complex. Endohedral rotations of fullerenes are of great interest due to the ability of the materials created on the basis of onion complexes to accumulate energy at rotational degrees of freedom. For such systems, a concept of temperature is not specified. In this paper, a closed description of the rotation of large molecules arranged in diamond shells is obtained in the framework of the classical approach. This description is used for C20@C80 diamond complex. Two different problems of molecular dynamics, distinguished by a fixing method for an outer shell of the considered bimolecular complex, are solved. In all the cases, the fullerene rotation frequency is calculated. Since a class of possible motions for a single carbon body (molecule) consists of rotations and translational displacements, the paper presents the equations determining each of these groups of motions. Dynamic equations for rotational motions of molecules are obtained employing the moment of momentum theorem for relative motions of the system near the fullerenes’ centers of mass. These equations specify the operation of the complex as a molecular pendulum. The equations of motion of the fullerenes’ centers of mass determine vibrations in the system, i.e. the operation of the complex as a molecular oscillator.

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McPhee, J. J., and R. N. Dubey. "Dynamics of Multibody Systems With Known Configuration Changes." Journal of Applied Mechanics 58, no. 1 (March 1, 1991): 215–21. http://dx.doi.org/10.1115/1.2897153.

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The equations of motion are derived for a system with inertial properties that are varying in time as a result of known relative motions between the rigid bodies comprising the system. This vector-dyadic formulation has been encoded into a computer program, making use of the conformal rotation vector for the representation of rotations. The numerical simulation of two different physical systems is presented in order to illustrate the dynamic effects of the changing inertial properties, and the usefulness of the encoded formulation for modeling these effects.

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Dais, Photis, and George Fainos. "Motional behavior of "asperlin" in solution. A 13C spin-lattice relaxation study." Canadian Journal of Chemistry 64, no. 3 (March 1, 1986): 560–65. http://dx.doi.org/10.1139/v86-090.

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l3C nuclear magnetic resonance spin-lattice relaxation times (T1) have been used to probe the motional behavior of 5-acetoxy-5,6-dihydro-6-(1,2-epoxypropyl)-2-pyrone ("asperlin") in dimethyl sulfoxide solution. This molecule offers structural features suited to a study of internal motions, i.e., epoxypropyl and methyl internal motions superimposed on an anisotropic overall reorientation. The rigidity of the pyrone ring and its semiplanar conformation result in an overall ellipsoidal shape, and hence the rotational dynamics of asperlin are adequately approximated by the diffusion of a prolate ellipsoid with the major axis passing through the C(2)—H(2) bond. The description of the internal motion of the epoxypropyl ring is strongly model dependent. Furthermore, the relaxation data for the oxirane ring carbons do not uniquely define a dynamic model. Due to similarities in the activation energies of the overall and internal motions, based on temperature-dependent measurements, it has not been feasible to interpret the relaxation data by a single type of motion. Internal rotation of the epoxymethyl substituent is rationalized by applying the stochastic diffusion model of multiple internal rotations

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EISENGA, A. H. M., R. VERZICCO, and G. J. F. VAN HEIJST. "Dynamics of a vortex ring moving perpendicularly to the axis of a rotating fluid." Journal of Fluid Mechanics 354 (January 10, 1998): 69–100. http://dx.doi.org/10.1017/s0022112097007702.

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The dynamics of a vortex ring moving orthogonally to the rotation vector of a uniformly rotating fluid is analysed by laboratory experiments and numerical simulations. In the rotating system the vortex ring describes a curved trajectory, turning in the opposite sense to the system's anti-clockwise rotation. This behaviour has been explained by using the analogy with the motion of a sphere in a rotating fluid for which Proudman (1916) computed the forces acting on the body surface. Measurements have revealed that the angular velocity of the vortex ring in its curved trajectory is opposite to the background rotation rate, so that the vortex has a fixed orientation in an inertial frame of reference and that the curvature increases proportionally to the rotation rate.The dynamics of the vorticity of the vortex ring is affected by the background rotation in such a way that the part of the vortex core in clockwise rotation shrinks while the anti-clockwise-rotating core part widens. By this opposite forcing on either side of the vortex core Kelvin waves are excited, travelling along the toroidal axis of the vortex ring, with a net mass flow which is responsible for the accumulation of passive scalars on the anti-clockwise-rotating core part. In addition, the curved motion of the vortex ring modifies its self-induced strain field, resulting in stripping of vorticity filaments at the front of the vortex ring from the anti-clockwise-rotating core part and at the rear from the core part in clockwise rotation. Vortex lines, being deflected by the main vortex ring due to induction of relative vorticity, are stretched by the local straining field and form a horizontally extending vortex pair behind the vortex ring. This vortex pair propagates by its self-induced motion towards the clockwise-rotating side of the vortex ring and thus contributes to the deformation of the ring core. The deflection of vortex lines from the main vortex ring persists during the whole motion and is responsible for the gradual erosion of the coherent toroidal structure of the initial vortex ring.

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Dong, Ruo-Yu, and Bing-Yang Cao. "Superhigh-speed unidirectional rotation of a carbon nanotube in a sheared fluid and its decoupled dynamics." RSC Advances 5, no. 108 (2015): 88719–24. http://dx.doi.org/10.1039/c5ra18901b.

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O’Reilly, O. M. "On the Computation of Relative Rotations and Geometric Phases in the Motions of Rigid Bodies." Journal of Applied Mechanics 64, no. 4 (December 1, 1997): 969–74. http://dx.doi.org/10.1115/1.2789008.

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In this paper, expressions are established for certain relative rotations which arise in motions of rigid bodies. A comparison of these results with existing relations for geometric phases in the motions of rigid bodies provides alternative expressions of, and computational methods for, the relative rotation. The computational aspects are illustrated using several examples from rigid-body dynamics: namely, the moment-free motion of a rigid body, rolling disks, and sliding disks.

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Banerjee, A. K., and T. R. Kane. "Dynamics of a Plate in Large Overall Motion." Journal of Applied Mechanics 56, no. 4 (December 1, 1989): 887–92. http://dx.doi.org/10.1115/1.3176187.

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Equations of motion are formulated for a thin elastic plate that is executing small motions relative to a reference frame undergoing large rigid body motions (three-dimensional rotation and translation) in a Newtonian reference frame. As an illustrative example, a spin-up maneuver for a simply-supported rectangular plate is examined, and the vibration modes of such a plate are used to show that the present theory captures the phenomenon of dynamic stiffening.

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Gozdźiewski, Krzysztof. "Rotational Dynamics of Janus and Epimetheus." International Astronomical Union Colloquium 165 (1997): 269–74. http://dx.doi.org/10.1017/s0252921100046662.

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AbstractWe investigate simplified models of flat rotational motion of the coorbital satellites of Saturn, Janus and Epimetheus. We try to verify the hypothesis of chaotic rotation of the moons, caused by gravitational interaction between them. The possibility of parametric resonance in the librations of Janus is also investigated.

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Pashkevich, V., and G. Eroshkin. "Application of the Spectral Analysis for Modeling the Rotations of the Moon." Artificial Satellites 45, no. 4 (January 1, 2010): 153–62. http://dx.doi.org/10.2478/v10018-011-0004-4.

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Application of the Spectral Analysis for Modeling the Rotations of the Moon The main purposes of this research are the development of the optimal spectral analysis schemes for the investigation of the rotational motion of the Moon and then the comparison between the result of the optimal spectral analysis of the rotational motions of the Earth and the Moon. Dynamics of the rotational motion of the Moon is studied numerically by using Rodrigues-Hamilton parameters over 418.9 year time interval. The results of the numerical solution of the problem are compared with the composite semi-analytical theory of the Moon rotation (SMR) represented by Cassini relations and the semi-analytical solutions of the lunar physical libration problem (Eckhardt, 1981), (Moons, 1982), (Moons, 1984), (Pešek, 1982). The initial conditions of the numerical integration are taken from SMR. The investigation of the discrepancies is carried out by the optimal spectral analysis methods for the Newtonian case. All the periodic terms representing the behavior of the residuals are interpreted as corrections to SMR semi-analytical theory. As a result, the Moon Rotation Series (MRS2010) is constructed, which is dynamically adequate to the DE200/LE200 ephemeris over 418.9 year time interval. A numerical solution for the Moon rotation is obtained anew with the new initial conditions calculated by means of MRS2010. The discrepancies between the new numerical solution and MRS2010 do not surpass 20 mas over 418.9 year time interval. The result of the comparison demonstrates that MRS2010 series represent more accurately the Moon rotation than SMR series.

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Céolin, Denis, Ji-Cai Liu, Vinícius Vaz da Cruz, Hans Ågren, Loïc Journel, Renaud Guillemin, Tatiana Marchenko, et al. "Recoil-induced ultrafast molecular rotation probed by dynamical rotational Doppler effect." Proceedings of the National Academy of Sciences 116, no. 11 (February 7, 2019): 4877–82. http://dx.doi.org/10.1073/pnas.1807812116.

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Observing and controlling molecular motion and in particular rotation are fundamental topics in physics and chemistry. To initiate ultrafast rotation, one needs a way to transfer a large angular momentum to the molecule. As a showcase, this was performed by hard X-ray C1s ionization of carbon monoxide accompanied by spinning up the molecule via the recoil “kick” of the emitted fast photoelectron. To visualize this molecular motion, we use the dynamical rotational Doppler effect and an X-ray “pump-probe” device offered by nature itself: the recoil-induced ultrafast rotation is probed by subsequent Auger electron emission. The time information in our experiment originates from the natural delay between the C1s photoionization initiating the rotation and the ejection of the Auger electron. From a more general point of view, time-resolved measurements can be performed in two ways: either to vary the “delay” time as in conventional time-resolved pump-probe spectroscopy and use the dynamics given by the system, or to keep constant delay time and manipulate the dynamics. Since in our experiment we cannot change the delay time given by the core-hole lifetime τ, we use the second option and control the rotational speed by changing the kinetic energy of the photoelectron. The recoil-induced rotational dynamics controlled in such a way is observed as a photon energy-dependent asymmetry of the Auger line shape, in full agreement with theory. This asymmetry is explained by a significant change of the molecular orientation during the core-hole lifetime, which is comparable with the rotational period.

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Ershkov, Sergey V., Dmytro Leshchenko, and Ayrat R. Giniyatullin. "A New Solving Procedure for the Kelvin–Kirchhoff Equations in Case of a Falling Rotating Torus." International Journal of Bifurcation and Chaos 31, no. 01 (January 2021): 2150010. http://dx.doi.org/10.1142/s0218127421500103.

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We present a new solving procedure in this paper for Kelvin–Kirchhoff equations, considering the dynamics of a falling rigid rotating torus in an ideal incompressible fluid, assuming additionally the dynamical symmetry of rotation for the rotating body, [Formula: see text]. The fundamental law of angular momentum conservation is used for the aforementioned solving procedure. The system of Euler equations for the dynamics of torus rotation is explored for an analytic way of presentation of the approximated solution (where we consider the case of laminar flow at slow regime of torus rotation). The second finding is that the Stokes boundary layer phenomenon on the boundaries of the torus also assumed additionally at the formulation of basic Kelvin–Kirchhoff equations (for which the analytical expressions for the components of fluid’s torque vector [Formula: see text] were obtained earlier). The results for calculating the components of angular velocity [Formula: see text] should then be used for full solving the momentum equation of Kelvin–Kirchhoff system. The trajectories of motion can be divided into, preferably, three classes: zigzagging, helical spiral motion, and the chaotic regime of oscillations.

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GUPTA, SHUCHI, KEYA DHARAMVIR, and V. K. JINDAL. "STRUCTURE AND DYNAMICS OF CARBON NANOTUBES IN CONTACT WITH GRAPHITE SURFACE AND OTHER CONCENTRIC NANOTUBES." International Journal of Modern Physics B 18, no. 07 (March 20, 2004): 1021–41. http://dx.doi.org/10.1142/s0217979204024513.

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Rigid carbon nanotubes in single and double walled formations, placed on a graphite surface, are bounced, rotated, slid and rolled. Various features associated with these motions are studied by assuming a 6-exp form of interaction (Van der Waal's attraction and Born–Mayer repulsion) among the C-atoms. Calculations reported here are for tubes of diameter around 14 Å, for which rigid tube approximation is known to work well. The oscillatory motion corresponding to rolling has the softest mode, whereas the one with highest frequency corresponds to bouncing. The energy barriers corresponding to these motions are also reported in this paper. The rotational and translational energy barriers for the movement of one nanotube with respect to the other one, in a double walled nanotube, have also been studied and it turns out that these tubes rotate and slide freely at room temperature. The translational energy barrier, in case of zigzag tubes, is interestingly, an order of magnitude higher than that of armchair tubes. In case of rotation, the case is reverse. Furthermore, it turns out that any drag of a concentric nanotube along the long axis direction is coupled with rotation, indicating easy screw motion instead of a simple drag. We also describe the dynamics of translational telescopic motion of a multiwalled nanotube assembly where a core oscillates within an open ended outer shell assembly.

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Hirashima, Masaya, Kazutoshi Kudo, Koji Watarai, and Tatsuyuki Ohtsuki. "Control of 3D Limb Dynamics in Unconstrained Overarm Throws of Different Speeds Performed by Skilled Baseball Players." Journal of Neurophysiology 97, no. 1 (January 2007): 680–91. http://dx.doi.org/10.1152/jn.00348.2006.

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This study investigated how the human CNS organizes complex three-dimensional (3D) ball-throwing movements that require both speed and accuracy. Skilled baseball players threw a baseball to a target at three different speeds. Kinematic analysis revealed that the fingertip speed at ball release was mainly produced by trunk leftward rotation, shoulder internal rotation, elbow extension, and wrist flexion in all speed conditions. The study participants adjusted the angular velocities of these four motions to throw the balls at three different speeds. We also analyzed the dynamics of the 3D multijoint movements using a recently developed method called “nonorthogonal torque decomposition” that can clarify how angular acceleration about a joint coordinate axis (e.g., shoulder internal rotation) is generated by the muscle, gravity, and interaction torques. We found that the study participants utilized the interaction torque to generate larger angular velocities of the shoulder internal rotation, elbow extension, and wrist flexion. To increase the interaction torque acting at these joints, the ball throwers increased muscle torque at the shoulder and trunk but not at the elbow and wrist. These results indicates that skilled ball throwers adopted a hierarchical control in which the proximal muscle torques created a dynamic foundation for the entire limb motion and beneficial interaction torques for distal joint rotations.

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WHITNEY, J. P., and R. J. WOOD. "Aeromechanics of passive rotation in flapping flight." Journal of Fluid Mechanics 660 (July 27, 2010): 197–220. http://dx.doi.org/10.1017/s002211201000265x.

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Flying insects and robots that mimic them flap and rotate (or ‘pitch’) their wings with large angular amplitudes. The reciprocating nature of flapping requires rotation of the wing at the end of each stroke. Insects or flapping-wing robots could achieve this by directly exerting moments about the axis of rotation using auxiliary muscles or actuators. However, completely passive rotational dynamics might be preferred for efficiency purposes, or, in the case of a robot, decreased mechanical complexity and reduced system mass. Herein, the detailed equations of motion are derived for wing rotational dynamics, and a blade-element model is used to supply aerodynamic force and moment estimates. Passive-rotation flapping experiments with insect-scale mechanically driven artificial wings are conducted to simultaneously measure aerodynamic forces and three-degree-of-freedom kinematics (flapping, rotation and out-of-plane deviation), allowing a detailed evaluation of the blade-element model and the derived equations of motion. Variations in flapping kinematics, wing-beat frequency, stroke amplitude and torsional compliance are made to test the generality of the model. All experiments showed strong agreement with predicted forces and kinematics, without variation or fitting of model parameters.

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Shaikh, Aasef G., Fatema F. Ghasia, J. David Dickman, and Dora E. Angelaki. "Properties of Cerebellar Fastigial Neurons During Translation, Rotation, and Eye Movements." Journal of Neurophysiology 93, no. 2 (February 2005): 853–63. http://dx.doi.org/10.1152/jn.00879.2004.

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The most medial of the deep cerebellar nuclei, the fastigial nucleus (FN), receives sensory vestibular information and direct inhibition from the cerebellar vermis. We investigated the signal processing in the primate FN by recording single-unit activities during translational motion, rotational motion, and eye movements. Firing rate modulation during horizontal plane translation in the absence of eye movements was observed in all non-eye-movement-sensitive cells and 26% of the pursuit eye-movement-sensitive neurons in the caudal FN. Many non-eye-movement-sensitive cells recorded in the rostral FN of three fascicularis monkeys exhibited convergence of signals from both the otolith organs and the semicircular canals. At low frequencies of translation, the majority of these rostral FN cells changed their firing rates in phase with head velocity rather than linear acceleration. As frequency increased, FN vestibular neurons exhibited a wide range of response dynamics with most cells being characterized by increasing phase leads as a function of frequency. Unlike cells in the vestibular nuclei, none of the rostral FN cells responded to rotational motion alone, without simultaneously exhibiting sensitivity to translational motion. Modulation during earth-horizontal axis rotation was observed in more than half (77%) of the neurons, although with smaller gains than during translation. In contrast, only 47% of the cells changed their firing rates during earth-vertical axis rotations in the absence of a dynamic linear acceleration stimulus. These response properties suggest that the rostral FN represents a main processing center of otolith-driven information for inertial motion detection and spatial orientation.

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Попиков, Petr Popikov, Клубничкин, and Vladislav Klubnichkin. "Mathematical model of energy saving hydraulic turning mechanism forestry manipulator." Forestry Engineering Journal 5, no. 4 (December 8, 2015): 223–34. http://dx.doi.org/10.12737/17426.

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Presented simulation mathematical model of the mechanism of rotation of the column manipulator with energy-saving hydraulic drive. The model takes into account three mechanical process: the rotational movement of the column arm around a vertical axis load sway relative attachment points on the boom arm and the piston motion of fluid accumulator. To describe the rotation of the column using the basic equation of dynamics of rotational motion. The load represented either as a mass point, when the dimen-sions are small and the proportionality, or a rod if the simulated moving manipulator logs or pipes.

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Laaksonen, Aatto, and Helena Kovacs. "Silver nitrate in aqueous solution and as molten salt: A molecular dynamics simulation and NMR relaxation study." Canadian Journal of Chemistry 72, no. 11 (November 1, 1994): 2278–85. http://dx.doi.org/10.1139/v94-290.

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Using molecular dynamics simulations, the motion and intermolecular interactions of the ions of silver nitrate are studied in aqueous solution and compared to the results obtained from simulations of molten AgNO3. The particularly interesting and experimentally frequently studied modes of reorientational motion (in-plane and end-over-end) of the planar nitrate ion have been determined from the simulation results. In accordance with earlier experimental results, the correlation times for the end-over-end rotation in aqueous solution are longer than those for the in-plane rotation, while the opposite is found to hold in the melt. In addition, the rotational motion of the nitrate ion in aqueous solution is experimentally studied using 14N relaxation measurements. Good agreement is found between the reorientational correlation times obtained from MD simulations and from NMR relaxation measurements.

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Awrejcewicz, Jan, Roman Starosta, and Grażyna Sypniewska-Kamińska. "Decomposition of the Equations of Motion in the Analysis of Dynamics of a 3-DOF Nonideal System." Mathematical Problems in Engineering 2014 (2014): 1–8. http://dx.doi.org/10.1155/2014/816840.

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The dynamic response of a nonlinear system with three degrees of freedom, which is excited by nonideal excitation, is investigated. In the considered system the role of a nonideal source is played by a direct current motor, where the central axis of the rotor is not coincident with the axis of rotation. This translation generates a torque whose magnitude depends on the angular velocity. During the system operation a general coordinate assigned to the nonideal source grows rapidly as a result of rotation. We propose the decomposition of the equations of motion in such a way to extract the solution which is directly related to the rotation of an unbalanced rotor. The remaining part of the solution describes pure oscillation depending on the dynamical behaviour of the whole system. The decomposed equations are solved numerically. The influence of selected system parameters on the rotor vibration is examined. The presented approach can be applied to separate vibration and rotation of motions in many other engineering systems.

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Wang, Joan Jing, and Hsiang-Kuang Chang. "Orbital motion and quasi-quantized disk around rotating neutron stars." International Journal of Modern Physics D 23, no. 06 (May 2014): 1450053. http://dx.doi.org/10.1142/s0218271814500539.

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In accreting neutron star (NS) low-mass X-ray binary (LMXB) systems, NS accretes material from its low-mass companion via a Keplerian disk. In a viscous accretion disk, inflows orbit the NS and spiral in due to dissipative processes, such as the viscous process and collisions of elements. The dynamics of accretion flows in the inner region of an accretion disk is significantly affected by the rotation of NS. The rotation makes NS, thus the spacetime metric, deviate from the originally spherical symmetry, and leads to gravitational quadrupole, on one hand. On the other hand, a rotating NS drags the local inertial frame in its vicinity, which is known as the rotational frame-dragging effect. In this paper, we investigate the orbital motion of accretion flows of accreting NS/LMXBs and demonstrate that the rotational effects of NS result in a band of quasi-quantized structure in the inner region of the accretion disk, which is different, in nature, from the scenario in the strong gravity of black hole arising from the resonance for frequencies related to epicyclic and orbital motions. We also demonstrate that such a disk structure may account for frequencies seen in X-ray variability, such as quasi-periodic oscillations (QPOs), and can be a potential promising tool for the investigation of photon polarization.

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Woźniak, Marek, Tomasz Szydłowski, and Krzysztof Siczek. "The effect of dynamics of the swash plate–slippers–piston assembly on friction torques in bearings in compressor of cooling aggregate." Mechanics and Mechanical Engineering 24, no. 1 (September 6, 2020): 42–55. http://dx.doi.org/10.2478/mme-2020-0006.

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AbstractThe swash plate type compressor utilized in car air conditioning devices and cooling system was analyzed in this study. Proper dynamic behavior of the components in such a compressor affected the correct functioning of the whole system. The aim of the study was to identify the characteristics of the main motion components in the swash plate–slippers–piston assembly of the compressor and to estimate the friction torques in its bearings. Some models of this assembly are elaborated and presented in the paper. The main components of slipper complex motion were identified, such as reciprocal motion along the axis of piston, rotation around piston axis, and short-time rotation around its own axis. Friction torque in axial bearing was higher than in journal bearing and varied with the rotational angle. Friction torques in journal bearings varied with the rotational angle and had different courses for two bearings of the compressor.

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Goc, Roman. "Simulation of the NMR Second Moment as a Function of Temperature in the Presence of Molecular Motion. Application to (CH3)3NBH3." Zeitschrift für Naturforschung A 57, no. 1-2 (February 1, 2002): 29–35. http://dx.doi.org/10.1515/zna-2002-1-202.

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The method for simulating the second moment of the NMR absorption spectrum as a function of temperature is presented. The second moment is first calculated as a function of the number of jumps of rotating molecules or their parts (like methyl groups). This number of jumps is rescaled into the frequency of internal rotation and these frequencies are recalculated into equivalent temperatures. The relation between frequency of rotation, and temperature is established on the basis of the Arrhenius relation υc= υo exp (-Ea/RT). The described method is then applied to the analysis of molecular motion in trimethylamine borane (CH3)3NBH3. The proposed method is especially useful in the case of complex structures, where combined motions are possible, because the NMR second moment is much more sensitive to the geometry of motion than the magnetic relaxation times T1 or T1p usualy used in studies of the internal dynamics of solids.

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Clow, Patricia A., and James G. McNally. "In Vivo Observations of Myosin II Dynamics Support a Role in Rear Retraction." Molecular Biology of the Cell 10, no. 5 (May 1999): 1309–23. http://dx.doi.org/10.1091/mbc.10.5.1309.

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To investigate myosin II function in cell movement within a cell mass, we imaged green fluorescent protein-myosin heavy chain (GFP-MHC) cells moving within the tight mound of Dictyostelium discoideum. In the posterior cortex of cells undergoing rotational motion around the center of the mound, GFP-MHC cyclically formed a “C,” which converted to a spot as the cell retracted its rear. Consistent with an important role for myosin in rotation, cells failed to rotate when they lacked the myosin II heavy chain (MHC−) or when they contained predominantly monomeric myosin II (3xAsp). In cells lacking the myosin II regulatory light chain (RLC−), rotation was impaired and eventually ceased. These rotational defects reflect a mechanical problem in the 3xAsp and RLC− cells, because these mutants exhibited proper rotational guidance cues. MHC− cells exhibited disorganized and erratic rotational guidance cues, suggesting a requirement for the MHC in organizing these signals. However, the MHC− cells also exhibited mechanical defects in rotation, because they still moved aberrantly when seeded into wild-type mounds with proper rotational guidance cues. The mechanical defects in rotation may be mediated by the C-to-spot, because RLC− cells exhibited a defective C-to-spot, including a slower C-to-spot transition, consistent with this mutant’s slower rotational velocity.

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Kim, Chang Boo, Chong Du Cho, and Hyeon Gyu Beom. "Dynamics of a Vibrating Micro Three-Axis Ring Gyroscope." Key Engineering Materials 306-308 (March 2006): 1241–46. http://dx.doi.org/10.4028/www.scientific.net/kem.306-308.1241.

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This paper presents electro-mechanical characteristics of a micro-machined vibrating silicon ring gyroscope which can measure angular velocity components about three orthogonal axes. The ring gyroscope has a ring connected to the gyroscope main body by support ligaments that are arranged with cyclic symmetry. The natural modes of its vibration can be distinguished into the in-plane motion and the out-of-motion that are coupled by the gyro-effect due to the rotation of the gyroscope main body. The motions of the ring are electro-statically driven, sensed and balanced by electrodes. The equations of motion are formulated with considering the electrostatic effects of electrodes. The measuring method of angular velocities of the gyroscope main body by force-torebalance is proposed. The dynamic characteristics of the ring gyroscope are discussed.

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Cordasco, Daniel, and Prosenjit Bagchi. "Intermittency and synchronized motion of red blood cell dynamics in shear flow." Journal of Fluid Mechanics 759 (October 24, 2014): 472–88. http://dx.doi.org/10.1017/jfm.2014.587.

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AbstractWe present the first full-scale computational evidence of intermittent and synchronized dynamics of red blood cells in shear flow. These dynamics are characterized by the coexistence of a tumbling motion in which the cell behaves like a rigid body and a tank-treading motion in which the cell behaves like a liquid drop. In the intermittent dynamics, we observe sequences of tumbling interrupted by swinging, as well as sequences of swinging interrupted by tumbling. In the synchronized dynamics, the tumbling and membrane rotation are observed to occur simultaneously with integer ratios of the rotational frequencies. These dynamics are shown to be dependent on the stress-free state of the cytoskeleton, and are explained based on the cell membrane energy landscape.

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Anderson, Daniel M., Maria Corsaro, Jonathan Horton, Tim Reid, and Padmanabhan Seshaiyer. "Tear film dynamics with blinking and contact lens motion." Mathematical Medicine and Biology: A Journal of the IMA 38, no. 3 (July 19, 2021): 355–95. http://dx.doi.org/10.1093/imammb/dqab010.

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Abstract We develop a lubrication theory-based mathematical model that describes the dynamics of a tear film during blinking and contact lens (CL) wear. The model extends previous work on pre-corneal tear film dynamics during blinking by coupling the partial differential equation for tear film thickness to a dynamic model for CL motion. We explore different models for eyelid motion and also account for possible voluntary and involuntary globe (eyeball) rotation that may accompany blinking. Boundary conditions for mass flux at the eyelids are also adapted to account for the presence and motion of the CL. Our predictions for CL motion compare reasonably with existing data. Away from the eyelids the pre-lens tear film (PrLTF) is shifted, relative to its pre-corneal counterpart, in the direction of CL motion. Near the eyelids, the inflow/outflow of fluid under the eyelids also influences the PrLTF profile. We also compare our PrLTF dynamics to existing in vivo tear film thickness measurements.

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Prsa, Mario, Danilo Jimenez-Rezende, and Olaf Blanke. "Inference of perceptual priors from path dynamics of passive self-motion." Journal of Neurophysiology 113, no. 5 (March 1, 2015): 1400–1413. http://dx.doi.org/10.1152/jn.00755.2014.

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The monitoring of one's own spatial orientation depends on the ability to estimate successive self-motion cues accurately. This process has become to be known as path integration. A feature of sequential cue estimation, in general, is that the history of previously experienced stimuli, or priors, biases perception. Here, we investigate how during angular path integration, the prior imparted by the displacement path dynamics affects the translation of vestibular sensations into perceptual estimates. Subjects received successive whole-body yaw rotations and were instructed to report their position within a virtual scene after each rotation. The overall movement trajectory either followed a parabolic path or was devoid of explicit dynamics. In the latter case, estimates were biased toward the average stimulus prior and were well captured by an optimal Bayesian estimator model fit to the data. However, the use of parabolic paths reduced perceptual uncertainty, and a decrease of the average size of bias and thus the weight of the average stimulus prior were observed over time. The produced estimates were, in fact, better accounted for by a model where a prediction of rotation magnitude is inferred from the underlying path dynamics on each trial. Therefore, when passively displaced, we seem to be able to build, over time, from sequential vestibular measurements an internal model of the vehicle's movement dynamics. Our findings suggest that in ecological conditions, vestibular afference can be internally predicted, even when self-motion is not actively generated by the observer, thereby augmenting both the accuracy and precision of displacement perception.

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Arkhipova, Inga. "Dynamics of a rigid rotor in the elastic bearings." Theoretical and Applied Mechanics 31, no. 1 (2004): 73–83. http://dx.doi.org/10.2298/tam0401073a.

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As a rule in the studies of a rigid rotor in the elastic bearings the authors consider the linear system corresponding to the plane-parallel motion and the effect of self-centring under unlimited growth of the rotation frequency. In the present paper rotor is considered as a mechanical system with four degrees of freedom. Different motions of a statically and dynamically unbalanced vertical rotor supported in the non-linear bearings are studied.

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Ahmed, Bushra A. "Newtonian and modified newtonian gravitational simulation of spiral galaxies." Iraqi Journal of Physics (IJP) 11, no. 21 (February 24, 2019): 20–27. http://dx.doi.org/10.30723/ijp.v11i21.363.

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One of the most powerful tools for any stellar dynamics is the N-body simulation. In an N-body simulation the motion of N particles is followed under their mutual gravitational attraction. In this paper the gravitational N-body simulation is described to investigate Newtonian and non- Newtonian (modified Newtonian dynamics) interaction between the stars of spiral galaxies. It is shown that standard Newtonian interaction requires dark matter to produce the flat rotational curves of the systems under consideration, while modified Newtonian dynamics (MOND) theorem provides a flat rotational curve and gives a good agreement with the observed rotation curve; MOND was tested as an alternative to the dark matter hypothesis. So that MOND hypothesis has generated better rotation curves than Newtonian theorem.

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Coates, Robert J. "The Crustal Dynamics Project." Symposium - International Astronomical Union 129 (1988): 337–38. http://dx.doi.org/10.1017/s0074180900134928.

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The Crustal Dynamics Project has been developing, deploying, and operating very-long-baseline interferometry (VLBI) systems and satellite laser ranging (SLR) systems for highly accurate geodetic measurements of global plate motion, plate stability, regional crustal deformation, and earth rotation/polar motion. Over the past 10 years, the measurement accuracies of these systems have been improved by a factor of 10 to the cm level. Plans are to continue these developments to reach mm level accuracies. The present deployment of the VLBI systems is primarily in the Northern Hemisphere. This network has produced measurements of the relative plate motion between the North American, Eurasian, and Pacific plates; the stability of the same plates; and the regional deformation at the North American/Pacific plate boundary in California and Alaska.

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Naito, Kozo, Tokio Takagi, Hideaki Kubota, and Takeo Maruyama. "The effect of multiple segment interaction dynamics on elbow valgus load during baseball pitching." Proceedings of the Institution of Mechanical Engineers, Part P: Journal of Sports Engineering and Technology 232, no. 4 (December 11, 2017): 285–94. http://dx.doi.org/10.1177/1754337117745239.

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Elbow valgus load generated in baseball pitching is a risk factor for throwing-related injuries. However, an induced acceleration analysis establishing the cause–effect relationship between elbow valgus load and causal joint kinematics is lacking. The purpose of this study was to identify the underlying mechanism of how the elbow valgus load is generated by muscular and non-muscular interactive torque effects. The throwing motions of five fastball pitches from 16 male collegiate baseball pitchers were measured by a three-dimensional motion capture system. The induced acceleration analysis developed in this study was used to separate the elbow valgus stress of the throwers into causal muscular and interactive torque components. The results showed that the shoulder internal rotation torque-induced component was greatest, accounting for 73.0% of the valgus-related contribution, while the other joint components in the muscular and interactive torque components were relatively smaller. This implied that the elbow valgus stress was highly influenced by the internal rotation torque effect, while the motion-dependent effect due to the trunk and shoulder kinematics was not influential. In conclusion, to reduce the risk of injury, pitchers should acquire proper coordination without excessive shoulder internal rotation action.

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Park, Youngwook, Hani Kang, Robert W. Field, and Heon Kang. "The frequency-domain infrared spectrum of ammonia encodes changes in molecular dynamics caused by a DC electric field." Proceedings of the National Academy of Sciences 116, no. 47 (November 5, 2019): 23444–47. http://dx.doi.org/10.1073/pnas.1914432116.

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Ammonia is special. It is nonplanar, yet in v = 1 of the umbrella mode (ν2) its inversion motion is faster than J = 0↔1 rotation. Does the simplicity of the Chemist's concept of an electric dipole moment survive the competition between rotation, inversion, and a strong external electric field? NH3 is a favorite pedagogical example of tunneling in a symmetric double-minimum potential. Tunneling is a dynamical concept, yet the quantitative characteristics of tunneling are expressed in a static, eigenstate-resolved spectrum. The inverting-umbrella tunneling motion in ammonia is both large amplitude and profoundly affected by an external electric field. We report how a uniquely strong (up to 108 V/m) direct current (DC) electric field causes a richly detailed sequence of reversible changes in the frequency-domain infrared spectrum (the v = 0→1 transition in the ν2 umbrella mode) of ammonia, freely rotating in a 10 K Ar matrix. Although the spectrum is static, encoded in it is the complete inter- and intramolecular picture of tunneling dynamics.

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Maeda, Takao, Takeshi Ozaki, Susumu Hara, and Shintaro Matsui. "Touchdown Dynamics of Planetary Lander with Translation–Rotation Motion Conversion Mechanism." Journal of Spacecraft and Rockets 54, no. 4 (July 2017): 973–80. http://dx.doi.org/10.2514/1.a33630.

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Watari, Nobuhiko, Masato Makino, Norio Kikuchi, Ronald G. Larson, and Masao Doi. "Simulation of DNA motion in a microchannel using stochastic rotation dynamics." Journal of Chemical Physics 126, no. 9 (March 7, 2007): 094902. http://dx.doi.org/10.1063/1.2538831.

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van der Marel, Roeland P., and Johannes Sahlmann. "FIRST GAIA LOCAL GROUP DYNAMICS: MAGELLANIC CLOUDS PROPER MOTION AND ROTATION." Astrophysical Journal 832, no. 2 (November 23, 2016): L23. http://dx.doi.org/10.3847/2041-8205/832/2/l23.

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Zheng, Z. C., and W. Li. "Dependence of radiated sound frequency on vortex core dynamics in multiple vortex interactions." Aeronautical Journal 113, no. 1142 (April 2009): 233–42. http://dx.doi.org/10.1017/s0001924000002906.

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Abstract With both theoretical analysis and measurement data, it has been identified previously that there exists a robust sound emission from a pair of counter-rotating aircraft wake vortices at the frequency of unsteady vortex core rotation. In a vortex system with multiple vortices, the sound emission frequency can be subjected to change because of interactions among the vortices. The behaviour of the influence, indicated by the ratio between the core size and the distance of the vortices and the underlining vortex core dynamic mechanisms, is investigated in this study. A vortex particle method is used to simulate the vortex core dynamics in two-dimensional, inviscid and incompressible flow. The flow field, in the form of vorticity, is employed as the source in the far-field acoustic calculation using a vortex sound formula. Cases of co-rotating vortices and a multiple-vortex system composed of two counter-rotating vortex pairs are studied for applications to aircraft wake vortex sound. The study shows, without vortex merging, individual frequencies can be clearly identified that are due each to core rotation (self induction) and co-rotating motion of a vortex centre around the other (mutual induction). The ratio of the core size and the distance between vortices does not seem to significantly influence the frequency of vortex core rotation. With vortex merging, a single frequency due to the merged vortex core is generated.

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Robinson, James D., and M. John D. Hayes. "THE DYNAMICS OF A SINGLE ALGEBRAIC SCREW PAIR." Transactions of the Canadian Society for Mechanical Engineering 35, no. 4 (December 2011): 491–503. http://dx.doi.org/10.1139/tcsme-2011-0029.

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The algebraic screw pair, or A-pair, represents a new class of kinematic constraint that exploits the self-motions inherent to a specific configuration of Griffis-Duffy platform. Using the A-pair as a joint in a hybrid parallel-serial kinematic chain results in a sinusoidal coupling of rotation and translation between adjacent links. The resulting linkage is termed an A-chain. This paper reveals the dynamic equations of motion of a single A-pair and examines the impact of the inertial properties of the legs of the A-pair on the dynamics. A numerical example illustrates the impact of the leg effects from different perspectives and shows that while the gravity effects of the legs are significant, it may be possible to neglect the leg kinetic energy from the dynamics model.

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WALSH, JAMES A. "ROTATION VECTORS FOR TORAL MAPS AND FLOWS: A TUTORIAL." International Journal of Bifurcation and Chaos 05, no. 02 (April 1995): 321–48. http://dx.doi.org/10.1142/s0218127495000284.

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This paper is an introduction to the concept of rotation vector defined for maps and flows on the m-torus. The rotation vector plays an important role in understanding mode locking and chaos in dissipative dynamical systems, and in understanding the transition from quasiperiodic motion on attracting invariant tori in phase space to chaotic behavior on strange attractors. Throughout this article the connection between the rotation vector and the dynamics of the map or flow is emphasized. We begin with a brief introduction to the dimension one setting, in which case the rotation vector reduces to the well known rotation number of H. Poincaré. A survey of the main results concerning the rotation number and bifurcations of circle maps is presented. The various definitions of rotation vector in the higher dimensional setting are then introduced with emphasis again placed on how certain properties of the rotation set relate to the dynamics of the map or flow. The dramatic differences between results in dimension two and results in higher dimensions are also presented. The tutorial concludes with a brief introduction to extensions of the concept of rotation vector to the setting of dynamical systems defined on surfaces of higher genus.

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Xu, Y., M. J. Reid, L. Moscadelli, K. M. Menten, X. W. Zheng, A. Brunthaler, B. Zhang, K. L. J. Rygl, J. J. Li, and A. Sanna. "Methanol Maser Parallaxes and Proper Motions." Proceedings of the International Astronomical Union 8, S287 (January 2012): 368–76. http://dx.doi.org/10.1017/s1743921312007326.

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AbstractDue to their compactness, persistence and slow motion, Class II CH3OH masers are excellent targets for parallax and proper motion measurements for massive star-forming regions in the Galactic Disk. These measurements can be used to improve our understanding of the spiral structure and dynamics of the Milky Way. At the same time, Class II CH3OH masers can also be used to study gas kinematics close to the exciting star, tracing rotation, infall and/or outflow motions.

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Zhao, Yongjie, and Feng Gao. "Inverse dynamics of the 6-dof out-parallel manipulator by means of the principle of virtual work." Robotica 27, no. 2 (March 2009): 259–68. http://dx.doi.org/10.1017/s0263574708004657.

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SUMMARYIn this paper, the inverse dynamics of the 6-dof out-parallel manipulator is formulated by means of the principle of virtual work and the concept of link Jacobian matrices. The dynamical equations of motion include the rotation inertia of motor–coupler–screw and the term caused by the external force and moment exerted at the moving platform. The approach described here leads to efficient algorithms since the constraint forces and moments of the robot system have been eliminated from the equations of motion and there is no differential equation for the whole procedure. Numerical simulation for the inverse dynamics of a 6-dof out-parallel manipulator is illustrated. The whole actuating torques and the torques caused by gravity, velocity, acceleration, moving platform, strut, carriage, and the rotation inertia of the lead screw, motor rotor and coupler have been computed.

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Chen, Wei, Yuelin Shen, Rongbing Chen, Zhengxin Zhang, and Sheldon Andre Rawlins. "Simulating Drillstring Dynamics Motion and Post-Buckling State with Advanced Transient Dynamics Model." SPE Drilling & Completion 36, no. 03 (February 22, 2021): 613–27. http://dx.doi.org/10.2118/199557-pa.

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Summary As drilling sections become deeper and longer, transferring more weight downhole to improve rate of penetration is the primary concern for the operator. Drillstring dynamics and buckling are some primary limiters for drilling efficiency. Aggressive drilling parameters may lead to severe downhole dynamics, which leads to cutter breakage and tool damage. When axial compression exceeds a certain threshold, the drillstring buckles sinusoidally inside the wellbore first, followed by helical buckling. Buckling leads to accelerated joint wear, tool fatigue failures, and lower drilling efficiency. To better manage drillstring dynamics and buckling, we propose a method of simulating drillstring dynamics motion and postbuckling state using an advanced transient dynamics model. An analysis methodology was developed on the basis of the finite element transient dynamics model. The model captures the enriched physics of drillstring dynamics and loading: the large deformation of buckled drillstring, the strong nonlinearity of contact and friction forces, and the dynamically triggered instability caused by drilling rotation. Transient dynamics simulations are conducted for drillstring with the actual well trajectory and rotation speed. The weight on bit (WOB) is ramped up gradually, and the drillstring deformation is monitored to detect the onset of buckling or dynamics instability. To conduct the model validation, the buckling inception loads predicted by the model are compared against the analytical equation of critical buckling loads. A field extended reach drilling (ERD) job was simulated by the model. The downhole weight and torque data from the measurement-while-drilling (MWD) tool was used to validate the weight transfer prediction by the model. Most existing buckling theories use the analytical equations of critical buckling load, which were normally derived on the basis of the idealized assumptions, such as perfect wellbore shape and uniform tubular geometry. The proposed method simulates the drillstring behaviors in the field drilling conditions and aims to capture effects of wellbore friction and string rotation. The transient dynamics model is capable of simulating drillstring dynamics movement (whirling and snaking) and weight lockup under severe helical buckling. An automatic method is proposed to interpret the drillstring behaviors from the simulation results. Using the transient dynamics model, the procedure presented in this article can simulate the dynamics and buckling behaviors of drillstring and help mitigate associated risks in well-planning and execution phases.

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Khater, T. T., J. F. Baker, and B. W. Peterson. "Dynamics of Adaptive Change in Human Vestibulo-Ocular Reflex Direction." Journal of Vestibular Research 1, no. 1 (July 1, 1990): 23–29. http://dx.doi.org/10.3233/ves-1990-1103.

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Adaptive modification of vestibulo-ocular reflex (VOR) direction was characterized in humans by recording vertical and horizontal VOR eye movements during horizontal rotations in darkness at frequencies of 0.05 to 1 Hz before and after exposure to a VOR direction adaptation procedure. This procedure paired yaw horizontal vestibular rotation at 0.25 Hz with synchronous pitch vertical optokinetic motion. Saccades were removed from eye position records and VOR gain and phase were recorded. With an onset time constant of 36 min, the VOR measured during horizontal rotation in complete darkness acquired a vertical component in phase with the optokinetic stimulus presented during adaptation. The amplitude of this newly acquired vertical VOR component was maximal during rotation at the frequency of adaptation; at other frequencies, the amplitude was lower, but still significant. Unlike VOR direction adaptation in cats, the phase of the adaptive VOR component in humans did not show significant leads or lags at test frequencies below or above the adaptation frequency. These data suggest that, like the cat, the human VOR can be directionally adapted, and the pathways involving the adaptive component of the VOR are frequency specific.

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Ishimaru, Shin’ichi, and Ryuichi Ikeda. "NMR Studies on Dynamics of Water Intercalated in Clay Minerals." Zeitschrift für Naturforschung A 54, no. 6-7 (July 1, 1999): 431–36. http://dx.doi.org/10.1515/zna-1999-6-714.

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Abstract The dynamics of water molecules intercalated in D2O saturated synthetic and natural smectites, and a synthetic Na-fluormica were studied by measurements of solid state 2H NMR spectra and spin-lattice relaxation times at 150 - 370 K. The obtained results could be explained by the 2-site flip, the C2 rotation and the isotropic rotation of the D2O molecules in smectites. In fluormica, the isotropic motion was undetectable, but the axial rotation of the hydration sphere as a whole was observed. The activation energies and correlation times of the C2 rotation were almost independent of the interlayer cations but depended on the character of clay-layers.

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Kozlowski, Ryan, Hu Zheng, Karen E. Daniels, and Joshua E. S. Socolar. "Particle dynamics in two-dimensional point-loaded granular media composed of circular or pentagonal grains." EPJ Web of Conferences 249 (2021): 06010. http://dx.doi.org/10.1051/epjconf/202124906010.

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Granular packings exhibit significant changes in rheological and structural properties when the rotational symmetry of spherical or circular particles is broken. Here, we report on experiments exploring the differences in dynamics of a grain-scale intruder driven through a packing of either disks or pentagons, where the presence of edges and vertices on grains introduces the possibility of rotational constraints at edge-edge contacts. We observe that the intruder’s stick-slip dynamics are comparable between the disk packing near the frictional jamming fraction and the pentagonal packing at significantly lower packing fractions. We connect this stark contrast in packing fraction with the average speed and rotation fields of grains during slip events, finding that rotation of pentagons is limited and the flow of pentagonal grains is largely confined in front of the intruder, whereas disks rotate more on average and circulate around the intruder to fill the open channel behind it. Our results indicate that grain-scale rotation constraints significantly modify collective motion of grains on mesoscopic scales and correspondingly enhance resistance to penetration of a local intruder.

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Fiori, Simone. "Model Formulation Over Lie Groups and Numerical Methods to Simulate the Motion of Gyrostats and Quadrotors." Mathematics 7, no. 10 (October 10, 2019): 935. http://dx.doi.org/10.3390/math7100935.

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The present paper recalls a formulation of non-conservative system dynamics through the Lagrange–d’Alembert principle expressed through a generalized Euler–Poincaré form of the system equation on a Lie group. The paper illustrates applications of the generalized Euler–Poincaré equations on the rotation groups to a gyrostat satellite and a quadcopter drone. The numerical solution of the dynamical equations on the rotation groups is tackled via a generalized forward Euler method and an explicit Runge–Kutta integration method tailored to Lie groups.

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Lee, Hyungu, Jung Yeon Hwang, Dong In Kim, Shincheol Lee, Sung-Hoon Lee, and Ji Sun Shin. "Understanding Keystroke Dynamics for Smartphone Users Authentication and Keystroke Dynamics on Smartphones Built-In Motion Sensors." Security and Communication Networks 2018 (2018): 1–10. http://dx.doi.org/10.1155/2018/2567463.

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Personal Identification Numbers (PINs) and pattern drawing have been used as common authentication methods especially on smartphones. Such methods, however, are very vulnerable to the shoulder surfing attack. Thus, keystroke dynamics that authenticate legitimate users based on their typing manner have been studied for years. However, many of the studies have focused on PC keyboard keystrokes. More studies on mobile and smartphones keystroke dynamics are warranted; as smartphones make progress in both hardware and software, features from smartphones have been diversified. In this paper, using various features including keystroke data such as time interval and motion data such as accelerometers and rotation values, we evaluate features with motion data and without motion data. We also compare 5 formulas for motion data, respectively. We also demonstrate that opposite gender match between a legitimate user and impostors has influence on authenticating by our experiment results.

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Roukala, Juho, Michal Straka, Stefan Taubert, Juha Vaara, and Perttu Lantto. "Ratcheting rotation or speedy spinning: EPR and dynamics of Sc3C2@C80." Chemical Communications 53, no. 64 (2017): 8992–95. http://dx.doi.org/10.1039/c7cc04695b.

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Doi, Masahiro, Yasuhisa Hasegawa, and Toshio Fukuda. "Control of Smooth Biped Walking by Means of Heel-Off Motion." Journal of Robotics and Mechatronics 19, no. 3 (June 20, 2007): 353–60. http://dx.doi.org/10.20965/jrm.2007.p0353.

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We propose the control method of biped walking controlled by heel liftoff that eliminates impact when the foot contacts the walking surface that makes walking unstable. In presenting sagittal motion with heel liftoff, we use an approximate 1-mass model and derive dynamics based on this model. Sagittal motion involves two centers of rotation: the ankle joint (phase 1) and the toe (phase 2). In phase 2, heel leftoff lowers the impact when the foot contacts the walking surface. 1D autonomous dynamics (phase) around the contact point is derived by applying Passive Dynamic Autonomous Control, which we proposed previously [15, 16] to dynamics in both phases. Based on this dynamics, we propose simple stabilizing control by varying the Center of Gravity (COG) trajectory in heel-off phase is proposed, and the motion period of the sagittal motion that is employed in order to synchronize the lateral and sagittal motion is calculated. Numerical simulation confirmed that walking dynamics converges at a certain state, and that heel liftoff reduced impact when the foot contacted the walking surface. We studied the energy efficiency of heel-off walking and proposed the mechanics to improve energy efficiency.

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Yu, Jianghong, Ran Zhang, Wen Yang, and Qishui Yao. "Dynamic Contact Characteristics of Elastic Composite Cylindrical Roller Bearing." Open Mechanical Engineering Journal 9, no. 1 (September 17, 2015): 703–8. http://dx.doi.org/10.2174/1874155x01509010703.

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Elastic composite cylindrical roller bearing is a kind of new bearing. In view of its structural particularity, explicit dynamics finite element model of elastic composite cylindrical roller bearing is established by utilizing ABAQUS/EXPLICIT. Dynamic responses of elastic composite cylindrical roller bearing are analyzed and response analysis is compared under different radial loads and rotation speeds. Dynamic responses of elastic composite cylindrical roller bearing are analyzed and response analysis is compared under different radial loads and rotation speeds. Results show that rolling and holder lag in rotation is as being compared to inner ring. The motion processes of all the holder, inner ring and roller have certain periodicity. Fluctuation amplitude of inner ring displacement increases with load. Response increases with rotation speed when amplification decreases. Analysis results can offer beneficial reference for further research on dynamic characteristics of elastic composite cylindrical roller bearing.

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Journal articles on the topic 'Rotation motion – Dynamics'

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