Rotation In Horizontal Plane Research Articles

Characterization of ballast particle’s movement associated with loading cycle, magnitude and frequency using SmartRock sensors

SmartRock has recently been adopted in obtaining the particle-scale characteristics of ballast track and gives microscopic explanation of track performance under cyclic loads, such as degradation and reinforcement. We notice that the contact state of individual ballast particles changes with loading cycles, which in reverse gives rise to different particle movements. The changes of contact state and particle movements may accumulate as loading cycle increases and could be considerable. This makes the response of individual particles uncertain and thus brings practical difficulties in evaluating the performance of ballast track via particle-scale characteristics, especially for long-term loading. In order to learn more about the response uncertainty of individual particles, this study conducts a full size model test to investigate the variation of particle movement and inter-particle normal contact force with loading cycle, amplitude as well as frequency by using SmartRocks. The equivalent axle load ranges from 14 to 36 t, the frequency of the cyclic loading varies from 1 to 18 Hz. Two smart rocks were placed below the sleeper end and the shoulder region respectively. It is found that the long-term variation of particle’s movements and contact force with loading cycle show obvious fluctuation due to the continuous accumulated changes of particle’s contact state. While particle’s movements are generally stable during short-term loading. The movements of SmartRock beneath sleeper end are positively correlated with loading magnitude and frequency, nevertheless also shows a characteristic independent on loading cycles, magnitude as well as frequency: particles’ rotation in horizontal plane is mainly permanent rotation (accumulated rotation), while particle’s rotation in planes perpendicular to the lateral and longitudinal directions is mainly recoverable rotation. The influences of loading magnitude and frequency on ballast particle movements are found different. The results provide effective particle-scale indicators for investigations related to ballast track.

Biomechanical Performance of Habitually Barefoot and Shod Runners during Barefoot Jogging and Running

The purpose of this study was to evaluate the biomechanical performances, running stability of habitually barefoot (BR) and shod runners (SR) during barefoot jogging and running. Ten healthy male subjects, 5 habitually shod runners and 5 habitually barefoot runners, from two different ethnics participated in this study. Subjects performed jogging (2m/s) and running (4m/s) along a 10-m runway. Three-dimensional lower-limb kinematics, ground reaction force, center of pressure (COP) and contact time (CT), were collected during testing. During jogging and running, all participants adopted rear-foot strike pattern, SR had larger VALR. SR showed significantly larger lower-limb range of motion (ROM) in sagittal plane, significantly larger hip abduction and opposite knee ROM in frontal plane, as well as significantly larger ankle internal rotation in horizontal plane. All participants’ CT showed decreased trend with running speed up; and SR was significantly longer than BR; BR and SR in COP showed different trajectories, especially forefoot and rearfoot areas. Habitually barefoot and shod runner from different ethnics still exist significant differences in lower-extremity ROM; and different foot morphological of participants is an important influential factor for these variations.

The effect of passive rotation in horizontal plane on perception of moving sound images

During the standard step examination in the rotary chair Nydiag 200 the authors, alongside with the rotary nystagmus, registered the evaluation of acoustic images motion direction. During the initial 20 seconds of the patient rotation, the patient, reliably more frequently than at rest, evaluated the acoustic images moving to the right as those moving to the left. The changes of localization were made in the direction opposite to that of rotation. No reliable changes have been found during the reverse movement. During the initial 20 seconds after patient rotation to the left the direction of the change of localization coincided with the movement direction. The revealed asymmetry of localization of the moving acoustic images during the rotation in a horizontal plane supports observations of Lewald and Karnath (2001) about asymmetrical effect of rotation to the right and to the left on localization of immobile acoustic images and brings up a question about the role of otolith asymmetry in the interactions of vestibular and auditory sensory systems.

Efficacy of En Bloc Direct Vertebral Body Derotation (Dvbd) in Idiopathic Scoliosis Treatment

Introduction Vertebral axial rotation in horizontal plane is a component of spinal deformity in scoliosis. Greater axial rotation is related with inclination to curve progression, contributes to rib hump development. Therefore the correction of axial deformity appears as an obvious component of scoliosis correction. However clinical efficiency and complication risk of derotation maneuvers is still not established. The object of the study was to assess horizontal correction obtained with en bloc direct vertebral body derotation (DVBD) and the influence of the maneuver on coronal and sagittal correction of the spine in patients undergoing surgical scoliosis correction. Material and Methods 36 patients after surgical correction of idiopathic scoliosis were included into study. Authors analyzed two groups; adolescents and adults. All patients underwent posterior fusion with pedicle screws only instrumentation. 15 (20 curves) patients were corrected by rod derotation only and 21 (26 curves) underwent rod derotation and direct en bloc vertebral derotation (DVBD). Measurements according to Cobb method were performed on X-rays obtained before and post surgery - coronal plane curves, sagittal profile (T2-T12, T5-T12, L1-S1). Spine flexibility was assessed of prone bending X-rays. Axial rotation was determined on CT scans obtained intraoperatively (O-Arm, Medtronic) and postoperative CT scan. Rotation assessment was done according to the method described by Aaro and Dahlborn. Results The comparison of axial rotation prior to correction and post correction revealed decrease of axial apical vertebral rotation in both DVBD and non DVBD groups. However in DVBD group vertebral derotation was greater than in non DVBD group and it was confirmed in statistic analysis. Amount of axial derotation was similar in both adults and adolescents. Analysis of coronal curves showed statistically significant better correction in (DVBD) group and obviously better correction was possible in flexible than stiff curves. DVBD did not improve but also did not decrease kyphosis comparing to pre op measurements and results from non DVBD group. This statement concerned both T2-T12, T5-T12 measurements. Neither flexibility nor stiffness of the curves influenced kyphosis results. Conclusion Direct vertebral body derotation is a relevant maneuver to improve correction in idiopathic scoliosis, either in coronal or sagittal plane. It may be useful technique in adolescent as well as adult patients.

Design and Fabrication of a Ball Projecting Machine

To make a ball projecting machine which pitches various kinds of balls either soft, leather, baseball or tennis ball at desired line and length as required. It can throw the ball at predetermined speed with required spin/swing effect. Problem with the existing machines is that they are very expensive and because of very low competition they ask for extremely huge price. The project began from the research phase with the identification of basic components used in the making of bowling machine. A thorough review of the theory and operations involved in a bowling machine were studied. A basic design was plotted and after review final design was made. Fabrication was done which involved operations on lathe, milling, grinding, welding machines etc. First 2 motors were coupled with the wheels, and then it was installed on a cylindrical bar which was installed on a base plate. A drive is used which is connected with the motors. The first worm and worm wheel set is installed on the rotating shaft on top of the base plate. Second similar set is installed at bottom. A power screw is welded at bottom which allows which fits inside a circular disc which carries corresponding threads. Its rotation about those threads would provide vertical lift and fall, also rotation in horizontal plane providing height adjustment and line change respectively. Finally three hollow cylindrical bars are welded at periphery of the circular plate holding power screw to form a tripod stand. The result is an efficient working bowling machine which is relatively much cheap in manufacturing. It could project the ball at various speeds with desired spin/swing effect. It also provides the facility to project various kinds of balls.

Experimental occlusal interferences. Part IV. Mandibular rotations induced by a pliable interference

In 12 subjects, a pliable, yet unbreakable, intercuspal interference (aluminum shim onlay splint; uniform height of 0.25 mm) was placed between either the right or left maxillary and mandibular second premolars and first molars. During brief and forceful biting (dynamic chewing stroke of about 20 kg force) the interference emulated a semisoft food bolus, and at the end of biting (subsequent static clenching stroke of about 20 kg force) it emulated a rigid metal interference. During dynamic/static biting, rotational electrognathography measured maximum frontal and horizontal plane torque of the right and left mandibular condyles. Eleven subjects (92%) showed frontal plane upward rotation (mean of 1.0 degree) of the condyle contralateral to the interference, and one subject (8%) showed frontal plane upward rotation (0.4 degree) of the condyle ipsilateral to the interference. Two subjects (17%) showed no horizontal plane rotation; seven subjects (58%) showed backward rotation (mean of 0.4 degree) of the condyle contralateral to the interference; and three subjects (25%) showed backward rotation (mean of 0.3 degree) of the condyle ipsilateral to the interference. It is suggested that, in the presence of an occlusal interference, mastication may have both short- and long-term detrimental effects.