Aging curve of neuromotor function by pronation and supination of forearms using three-dimensional wireless acceleration and angular velocity sensors

2012 ◽  
Author(s):  
M. Kaneko ◽  
H. Okui ◽  
G. Hirakawa ◽  
H. Ishinishi ◽  
Y. Katayama ◽  
...  
Keyword(s):  
Angular Velocity ◽  
Three Dimensional ◽  
Aging Curve ◽  
Neuromotor Function

Effect of Finite Rotations on Gyroscopic Sensing Devices

1958 ◽  
Vol 25 (2) ◽  
pp. 210-213
Author(s):  
L. E. Goodman ◽  
A. R. Robinson
Keyword(s):  
Angular Velocity ◽  
Three Dimensional ◽  
Time History ◽  
Simple Method ◽  
Finite Rotations ◽  
Actual Solution ◽  
History Of ◽  
Body Components ◽  
Guidance Systems ◽  
Three Body

Abstract The well-known noncommutativity of three-dimensional finite rotations has long been a curiosity in mechanics since, in actual solution of dynamical problems, the angular velocity, which is conveniently representable as a vector, plays a more natural role. In modern inertial guidance systems, however, the orientation of a body in space, i.e., a rotation, is of primary engineering interest. In this paper a simple method of determining orientation from the time history of three body components of angular velocity is developed by means of a new theorem in kinematics. As a special case of this theorem it is shown that a gyro subjected to a regime of rotations which returns it to the original space orientation will, in general, produce a residual signal. It will have experienced a nonzero and easily calculated mean angular velocity about its input axis. Some implications of the theorem for the design of inertial guidance systems and for the testing of gyros are discussed.

scholarly journals The magnetorotational instability prefers three dimensions

2020 ◽  
Vol 476 (2233) ◽  
pp. 20190622
Author(s):  
Jeffrey S. Oishi ◽  
Geoffrey M. Vasil ◽  
Morgan Baxter ◽  
Andrew Swan ◽  
Keaton J. Burns ◽  
...  
Keyword(s):  
Shear Rate ◽  
Angular Velocity ◽  
Laboratory Experiments ◽  
Three Dimensional ◽  
Linear Instability ◽  
Three Dimensions ◽  
Two Dimensional ◽  
Magnetorotational Instability ◽  
Dynamo Action ◽  
Wide Range

The magnetorotational instability (MRI) occurs when a weak magnetic field destabilizes a rotating, electrically conducting fluid with inwardly increasing angular velocity. The MRI is essential to astrophysical disc theory where the shear is typically Keplerian. Internal shear layers in stars may also be MRI-unstable, and they take a wide range of profiles, including near-critical. We show that the fastest growing modes of an ideal magnetofluid are three-dimensional provided the shear rate, S , is near the two-dimensional onset value, S c . For a Keplerian shear, three-dimensional modes are unstable above S  ≈ 0.10 S c , and dominate the two-dimensional modes until S  ≈ 2.05 S c . These three-dimensional modes dominate for shear profiles relevant to stars and at magnetic Prandtl numbers relevant to liquid-metal laboratory experiments. Significant numbers of rapidly growing three-dimensional modes remainy well past 2.05 S c . These finding are significant in three ways. First, weakly nonlinear theory suggests that the MRI saturates by pushing the shear rate to its critical value. This can happen for systems, such as stars and laboratory experiments, that can rearrange their angular velocity profiles. Second, the non-normal character and large transient growth of MRI modes should be important whenever three-dimensionality exists. Finally, three-dimensional growth suggests direct dynamo action driven from the linear instability.

Influence of Training on Maintenance of Equilibrium on a Tilting Platform

2003 ◽  
Vol 96 (1) ◽  
pp. 127-136 ◽  
Author(s):  
Chiarella Sforza ◽  
Gian Piero Grassi ◽  
Michela Turci ◽  
Nicola Fragnito ◽  
Giuliano Pizzini ◽  
...  
Keyword(s):  
Angular Velocity ◽  
Three Dimensional ◽  
Healthy Male ◽  
Specific Training ◽  
Male Athletes ◽  
Before And After ◽  
And Control ◽  
Experimental Group

To assess the influence of training on the maintenance of equilibrium on a tilting platform, 13 young healthy male athletes aged 19 to 33 years were randomly divided into experimental ( n = 7) and control ( n = 6) groups. Two experimental sessions were performed before and after a specific 4-wk. training by the experimental group. Subjects stood upright on a tilting platform. The athletes were asked to maintain the platform as horizontal as possible during a 30-sec. test. The three-dimensional movements of the platform versus the ground were recorded by using a computerized optoelectronic digitiser. The platform plane was calculated and its directrix computed. The area of oscillation and instantaneous angular velocity of the directrix at standardized height were calculated. In both groups the area of oscillation and the angular velocity were reduced in Session 2, but the reduction was significant only in the experimental group. Specific training can significantly improve skill at maintaining equilibrium in young healthy sport performers.

Biomechanical Comparison of a New Dynamic Ankle Orthosis to a Standard Ankle-Foot Orthosis During Walking

2020 ◽  
Vol 142 (5) ◽  
Author(s):  
Chloe L. Chung ◽  
Denis J. DiAngelo ◽  
Douglas W. Powell ◽  
Max R. Paquette
Keyword(s):  
Angular Velocity ◽  
Cartilage Damage ◽  
Three Dimensional ◽  
Frontal Plane ◽  
Ankle Injuries ◽  
Ankle Motion ◽  
Ankle Foot Orthosis ◽  
Plantar Pressures ◽  
Biomechanical Comparison ◽  
Foot Orthosis

Abstract Patients who sustain irreversible cartilage damage or joint instability from ankle injuries are likely to develop ankle osteoarthritis (OA). A dynamic ankle orthosis (DAO) was recently designed with the intent to offload the foot and ankle using a distractive force, allowing more natural sagittal and frontal plane ankle motion during gait. To evaluate its efficacy, this study compared ankle joint kinematics and plantar pressures among the DAO, standard double upright ankle-foot orthosis (DUAFO), and a nonorthosis control (CON) condition in healthy adults during walking. Ten healthy subjects (26 ± 3.8 yr; 69.6 ± 12.7 kg; and 1.69 ± 0.07 m) walked on a treadmill at 1.4 m/s in three orthosis conditions: CON, DAO, and DUAFO. Ankle kinematics were assessed using a three-dimensional (3D) motion capture system and in-shoe plantar pressures were measured for seven areas of the foot. DAO reduced hallux peak plantar pressures (PPs) compared to CON and DUAFO. PPs under toes 2–5 were smaller in DAO than DUAFO, but greater in DUAFO compared to CON. Early stance peak plantarflexion (PF) angular velocity was smaller in DAO compared to CON and DUAFO. Eversion (EV) ROM was much smaller in DUAFO compared to CON and DAO. Early stance peak eversion angular velocity was smaller in DAO and much smaller in DUAFO compared to CON. This study demonstrates the capacity of the DAO to provide offloading during ambulation without greatly affecting kinematic parameters including frontal plane ankle motion compared to CON. Future work will assess the effectiveness of the DAO in a clinical osteoarthritic population.

Simulation on Temperature Field of Gap Oil Film in Constant Flow Hydrostatic Center Frame

2011 ◽  
Vol 121-126 ◽  
pp. 4706-4710
Author(s):  
Yong Hai Li ◽  
Xiu Li Meng ◽  
Xiao Dong Yu ◽  
Bo Wu ◽  
Chun Li Gao ◽  
...  
Keyword(s):  
Temperature Field ◽  
Angular Velocity ◽  
Thermal Deformation ◽  
Three Dimensional ◽  
Constant Flow ◽  
Distribution Law ◽  
Simulation Research ◽  
Oil Film ◽  
Temperature Performance ◽  
Volume Method

In order to solve the thermal deformation of the hydrostatic center frame in the heavy type horizontal lathe, a simulation research concerning temperature field of hydrostatic center frame is described. The Finite Volume Method of CFX has been used to compute three-dimensional temperature field of gap fluid between workpiece and bearing pillow. This research theoretically analyzes the influence of angular velocity on the bearing temperature performance according to lubricating theory and computational fluid dynamics, and it has revealed its temperature distribution law of gap oil film. Results indicate that an improved characteristic will be affected by angular velocity easily, and oil cavity temperature increases by gradually with angular velocity enhancing. Through this method, the safety of a hydrostatic center frame can be forecasted, and the optimal design of such products can be achieved, so it can provide reasonable data for design, lubrication, experience and thermal deformation computation for hydrostatic center frame in the heavy type horizontal lathe.

Solution to Euler’s Gyrodynamics—I

1964 ◽  
Vol 31 (2) ◽  
pp. 325-328 ◽  
Author(s):  
C. F. Harding
Keyword(s):  
Differential Equation ◽  
Angular Velocity ◽  
Formal Solution ◽  
Three Dimensional ◽  
Rotation Group ◽  
Axially Symmetric ◽  
Free Case ◽  
Thrust Vector ◽  
Linear Differential ◽  
Constant Moment

A little used parameterization of the three-dimensional rotation group is taken as basis in deriving an easily integrable kinematic relation (a 4-vector linear differential equation) for the attitude rate, in terms of the present attitude and angular velocity of one reference frame relative to another. If the angular velocity is known and well behaved one obtains the exact solution from an iteration procedure explained in detail. The formal solution to a large class of rigid-body problems is thus implied; a particular one being that of an axially symmetric rocket with variable thrust vector and constant moment-of-inertia tensor which as such generalizes Jacobi’s torque-free case.

Changes in postural control strategy during quiet standing in individuals with knee osteoarthritis

2021 ◽  
pp. 1-8
Author(s):  
Kento Sabashi ◽  
Satoshi Kasahara ◽  
Harukazu Tohyama ◽  
Takeshi Chiba ◽  
Yuta Koshino ◽  
...  
Keyword(s):  
Standard Deviation ◽  
Angular Velocity ◽  
Postural Control ◽  
Knee Osteoarthritis ◽  
Lower Limb ◽  
Center Of Mass ◽  
Three Dimensional ◽  
Quiet Standing ◽  
Control Group ◽  
Knee Oa

BACKGROUND: Knee osteoarthritis (OA) impairs postural control and may be affected by how the lower limb joints are used. OBJECTIVE: To investigate how individuals with knee OA use lower limb joints for static postural control. METHODS: Ten patients with knee OA and thirteen healthy controls performed quiet standing for 30 s. The standard deviation of the center of mass (COM) and lower limb joint motions in the anterior-posterior (AP) and medial-lateral (ML) planes were calculated from three-dimensional marker trajectories. Pearson’s correlation analysis and independent t-tests were conducted to investigate the relationship between COM and lower limb joint motion and to compare group difference, respectively. RESULTS: The AP hip angular velocity alone in the knee OA group and the AP hip and knee angular velocity in the control group were significantly correlated with the AP COM velocity. The ML hip angular velocity was significantly correlated with the ML COM velocity in both groups. The knee OA group exhibited a significantly larger standard deviation of AP COM velocity than the control group. CONCLUSIONS: Individuals with knee OA depended solely on the contribution of the hip to the AP COM velocity, which could not be successfully controlled by the knee.

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