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1
He, Zhang-Ming, Deng-Long Wang, Yan-Chao She, Jian-Wen Ding und Xiao-Hong Yan. „Nonperiodic Oscillation of Bright Solitons in Condensates with a Periodically Oscillating Harmonic Potential 10.5560/ZNA.2012-0085“. Zeitschrift für Naturforschung A 67, Nr. 12 (01.12.2012): 723–28. http://dx.doi.org/10.5560/zna.2012-0085.
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Considering a periodically oscillating harmonic potential, we explored the dynamic properties of bright solitons in a Bose-Einstein condensate by using Darboux transformation. It is found that the soliton movement exhibits a nonperiodic oscillation under a slow oscillating potential, while it is hardly affected under a fast oscillating potential. Furthermore, the head-on and/or ‘chase’ collisions of two solitons have been obtained, which could be controlled by the oscillation frequency of the potential.
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Ortega-Jimenez, Victor Manuel, und Robert Dudley. „Aerial shaking performance of wet Anna's hummingbirds“. Journal of The Royal Society Interface 9, Nr. 70 (09.11.2011): 1093–99. http://dx.doi.org/10.1098/rsif.2011.0608.
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External wetting poses problems of immediate heat loss and long-term pathogen growth for vertebrates. Beyond these risks, the locomotor ability of smaller animals, and particularly of fliers, may be impaired by water adhering to the body. Here, we report on the remarkable ability of hummingbirds to perform rapid shakes in order to expel water from their plumage even while in flight. Kinematic performance of aerial versus non-aerial shakes (i.e. those performed while perching) was compared. Oscillation frequencies of the head, body and tail were lower in aerial shakes. Tangential speeds and accelerations of the trunk and tail were roughly similar in aerial and non-aerial shakes, but values for head motions in air were twice as high when compared with shakes while perching. Azimuthal angular amplitudes for both aerial and non-aerial shakes reached values greater than 180° for the head, greater than 45° for the body trunk and slightly greater than 90° for the tail and wings. Using a feather on an oscillating disc to mimic shaking motions, we found that bending increased average speeds by up to 36 per cent and accelerations of the feather tip up to fourfold relative to a hypothetical rigid feather. Feather flexibility may help to enhance shedding of water and reduce body oscillations during shaking.
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Zhang, Kai, Bo Song und Delan Zhu. „The Development of a Calculation Model for the Instantaneous Pressure Head of Oscillating Water Flow in a Pipeline“. Water 11, Nr. 8 (31.07.2019): 1583. http://dx.doi.org/10.3390/w11081583.
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Sinusoidal oscillating water flow at low pressure can improve the anti-clogging ability of an emitter in drip irrigation or the water distribution of a nozzle in sprinkler irrigation and reduce the cost and energy consumption of the irrigation system. In this study, the characteristics of instantaneous pressure head attenuation of oscillating water flow along a pipeline have been investigated. By using a complex function to solve the continuity equation and the momentum equation of a pipeline with water hammer motion and using the Darcy–Weisbach formula to estimate the head loss, a calculation model for the instantaneous pressure head of oscillating water flow along a pipeline was developed. The measured value of the amplitude of the pressure head and the average instantaneous pressure head in the experiments have been used to verify the corresponding pressure head calculated by the model. The results show that the amplitude of the pressure head and the average instantaneous pressure head decrease linearly along the pipeline. The calculated value of the amplitude of the pressure head and the average instantaneous pressure head are basically close to the corresponding measured pressure head. From the results of all the tests, the maximum relative error of the calculated and measured value of the amplitude of the pressure head along the pipeline was 9.44%. The maximum relative error of the calculated and measured value of the average instantaneous pressure head along the pipeline was 8.37%. Hence, the model can accurately predict the instantaneous pressure head of oscillating water flow along a pipe and provide a theoretical basis for the application of oscillating water flow in irrigation systems and the design of irrigation pipe networks.
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Li, Yan-Hom, und Shao-Chun Chen. „Propulsion Mechanism of Flexible Microbead Swimmers in the Low Reynolds Number Regime“. Micromachines 11, Nr. 12 (15.12.2020): 1107. http://dx.doi.org/10.3390/mi11121107.
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A propulsion mechanism for a flexible microswimmer constructed from superparamagnetic microbeads with different diameters and subjected to an oscillating field was studied experimentally and theoretically herein. Various types of artificial swimmers with different bending patterns were fabricated to determine the flexibility and an effective waveform for a planar beating flagellum. Waveform evolutions for various swimmer configurations were studied to determine the flexible mechanism of the swimmers. A one-armed microswimmer can propel itself only if the friction of its wavelike body is anisotropic. A swimmer with a larger head and a stronger magnetic dipole moment with a flexible tail allows the bending wave to propagate from the head toward the tail to generate forward thrust. The oscillating head and tail do not simultaneously generate positive thrust all the time within a period of oscillation. To increase the propulsion for a bending swimmer, this study proposes a novel configuration for a microbead swimmer that ensures better swimming efficiency. The ratio of the oscillation amplitude of the head to the length of the swimmer (from 0.26 to 0.28) produces a faster swimmer. On the other hand, the swimmer is propelled more effectively if the ratio of the oscillation amplitude of the tail to the length of the swimmer is from 0.29 to 0.33. This study determined the optimal configuration for a flexible microbead swimmer that generates the greatest propulsion in a low Reynolds number environment.
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Samokhin, Alexey. „On Monotonic Pattern in Periodic Boundary Solutions of Cylindrical and Spherical Kortweg–De Vries–Burgers Equations“. Symmetry 13, Nr. 2 (29.01.2021): 220. http://dx.doi.org/10.3390/sym13020220.
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We studied, for the Kortweg–de Vries–Burgers equations on cylindrical and spherical waves, the development of a regular profile starting from an equilibrium under a periodic perturbation at the boundary. The regular profile at the vicinity of perturbation looks like a periodical chain of shock fronts with decreasing amplitudes. Further on, shock fronts become decaying smooth quasi-periodic oscillations. After the oscillations cease, the wave develops as a monotonic convex wave, terminated by a head shock of a constant height and equal velocity. This velocity depends on integral characteristics of a boundary condition and on spatial dimensions. In this paper the explicit asymptotic formulas for the monotonic part, the head shock and a median of the oscillating part are found.
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IOALE', PAOLO, und DANTE GUIDARINI. „Methods for Producing Disturbances in Pigeon Homing Behaviour by Oscillating Magnetic Fields“. Journal of Experimental Biology 116, Nr. 1 (01.05.1985): 109–20. http://dx.doi.org/10.1242/jeb.116.1.109.
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Experiments were performed with homing pigeons treated before release with oscillating magnetic fields produced by small Helmholtz coils placed around the neck and on the head of the pigeon or by larger Helmholtz coils surrounding the cage of the birds. In both types of treatment, which both used a single frequency of about 0.14 Hz, the pigeons' initial orientation was strongly affected when the oscillation of the artificial magnetic field was square-shaped, whereas a triangular or sine-shaped variation had no effect.
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Zhang, Kai, Baoxu Zhang und Delan Zhu. „Development and Sensitivity Analysis of an Empirical Equation for Calculating the Amplitude of Pressure Head Loss of Oscillating Water Flow in Different Types of Pipe“. Water 12, Nr. 9 (28.08.2020): 2421. http://dx.doi.org/10.3390/w12092421.
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Low pressure oscillating water flow can reduce the investment and energy consumption of irrigation. It is also effective in reducing the clogging of an emitter and improving the spraying quality of sprinklers. In order to overcome the problem of the complex process in calculating the amplitude of the pressure head loss of oscillating water flow in different types of pipes, in this study, an empirical equation for the amplitude of the pressure head loss of oscillating water flow in different types of pipe has been developed. Further, validation experiments have been conducted to verify the accuracy of the calculated amplitudes of the pressure head loss by the empirical equation. The results show that average relative error between the measured and the calculated amplitudes of the pressure head loss by the empirical equation is 10.77%. Since the relative errors are small, it is an indication that the amplitudes of the pressure head loss calculated by the empirical equation are accurate. For the empirical equation developed in this study, the sensitivity of the model parameters has been analyzed. The results show that the amplitude of velocity, the internal pipe diameter, and the length of pipe are classified as highly sensitive. The average velocity, the period of oscillating water flow, and the modulus of elasticity of the pipe material are classified as sensitive. The thickness of the pipe wall is classified as medium sensitive. Compared with the calculation models of the existing researches, the empirical equation reduces the number of parameters required to be calculated, by which many complicated calculations are avoided, which greatly improves the computing efficiency. This is conducive to the efficient operation and management of oscillating water flow in irrigation pipe networks and also provides help for the optimal design of irrigation pipe networks.
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Yufeng Li, A. K. Menon und M. Sullivan. „An oscillating tester for head/disk interface durability study“. IEEE Transactions on Magnetics 31, Nr. 6 (1995): 3000–3002. http://dx.doi.org/10.1109/20.490250.
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Bulgakov, V., V. Adamchuk, І. Holovach und Ye Ihnatiev. „Mathematical model of the movement of a towed machine for cleaning beet tops residues from root crop heads“. Agricultural Science and Practice 4, Nr. 1 (15.04.2017): 3–10. http://dx.doi.org/10.15407/agrisp4.01.003.
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The work of a tractor-towed machine for cleaning beet top residues from root crop heads, when used with supporting pneumatic wheels, is accompanied with its oscillations in the vertical plane, which has consider- able impact on the quality of implementing the technological process. Therefore, the determination of opti- mal parameters for the cleaning machine, ensuring more stable movement of its cleaning working tool, in the longitudinal-vertical plane fi rst and foremost, is an important task of the mechanization of sugar beet grow- ing industry. Aim. To enhance the effi ciency of cleaning sugar beet top residues from root crop heads via the elaboration of the mathematical model of the oscillating movement of the towed machine for cleaning beet top residues from root crop heads in the longitudinal-vertical plane. Methods. The methods of building computational mathematical models for the functioning of agricultural machines and equipment, based on theoretical mechanics and advanced mathematics, were used. Results. The elaborated equivalent scheme of the movement of the towed cleaning machine was used to obtain the system of two non-linear differential equations for detailed study of the oscillations of the root crop head cleaner in the longitudinal-vertical plane while its supporting pneumatic wheels are moving along uneven soil surface. The mathematical model for the movement of the cleaner with horizontal cleaning roller, elaborated on the basis of initial dynamics equa- tions in the Lagrangian form of the second kind, allowed determining the connection between constructive and kinematic parameters of the vehicle and its oscillating characteristics. The established dependencies formed the prerequisites for further mathematical digital modelling of the parameters of the towed machine for cleaning of root crop heads with a horizontal cleaning roller. Conclusions. The established computation- al model allows optimizing the values of several parameters, characterizing the oscillations of the machine in the longitudinal-vertical plane.
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Ohorodnyk, N., K. Smolianinov und M. Ratsky. „Cellular and humoral immunity of carp at the action of biologically active additives“. Agricultural Science and Practice 4, Nr. 1 (15.04.2017): 70–73. http://dx.doi.org/10.15407/agrisp4.01.070.
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The work of a tractor-towed machine for cleaning beet top residues from root crop heads, when used with supporting pneumatic wheels, is accompanied with its oscillations in the vertical plane, which has consider- able impact on the quality of implementing the technological process. Therefore, the determination of opti- mal parameters for the cleaning machine, ensuring more stable movement of its cleaning working tool, in the longitudinal-vertical plane fi rst and foremost, is an important task of the mechanization of sugar beet grow- ing industry. Aim. To enhance the effi ciency of cleaning sugar beet top residues from root crop heads via the elaboration of the mathematical model of the oscillating movement of the towed machine for cleaning beet top residues from root crop heads in the longitudinal-vertical plane. Methods. The methods of building computational mathematical models for the functioning of agricultural machines and equipment, based on theoretical mechanics and advanced mathematics, were used. Results. The elaborated equivalent scheme of the movement of the towed cleaning machine was used to obtain the system of two non-linear differential equations for detailed study of the oscillations of the root crop head cleaner in the longitudinal-vertical plane while its supporting pneumatic wheels are moving along uneven soil surface. The mathematical model for the movement of the cleaner with horizontal cleaning roller, elaborated on the basis of initial dynamics equa- tions in the Lagrangian form of the second kind, allowed determining the connection between constructive and kinematic parameters of the vehicle and its oscillating characteristics. The established dependencies formed the prerequisites for further mathematical digital modelling of the parameters of the towed machine for cleaning of root crop heads with a horizontal cleaning roller. Conclusions. The established computation- al model allows optimizing the values of several parameters, characterizing the oscillations of the machine in the longitudinal-vertical plane.
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Teixeira, Luis Augusto, Joane de Figueiredo Serpa Coutinho und Daniel Boari Coelho. „Regulation of dynamic postural control to attend manual steadiness constraints“. Journal of Neurophysiology 120, Nr. 2 (01.08.2018): 693–702. http://dx.doi.org/10.1152/jn.00941.2017.
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In daily living activities, performance of spatially accurate manual movements in upright stance depends on postural stability. In the present investigation, we aimed to evaluate the effect of the required manual steadiness (task constraint) on the regulation of dynamic postural control. A single group of young participants ( n = 20) were evaluated in the performance of a dual posturo-manual task of balancing on a platform oscillating in sinusoidal translations at 0.4-Hz (low) or 1-Hz (high) frequencies while stabilizing a cylinder on a handheld tray. Manual task constraint was manipulated by comparing the conditions of keeping the cylinder stationary on its flat or round side, corresponding to low and high manual task constraints, respectively. Results showed that in the low oscillation frequency the high manual task constraint led to lower oscillation amplitudes of the head, center of mass, and tray, in addition to higher relative phase values between ankle/hip-shoulder oscillatory rotations and between center of mass/center of pressure-feet oscillations as compared with values observed in the low manual task constraint. Further analyses showed that the high manual task constraint also affected variables related to both postural (increased amplitudes of center of pressure oscillation) and manual (increased amplitude of shoulder rotations) task components in the high oscillation frequency. These results suggest that control of a dynamic posturo-manual task is modulated in distinct parameters to attend the required manual steadiness in a complex and flexible way. NEW & NOTEWORTHY We evaluated dynamic postural control on a platform oscillating in sinusoidal translations at different frequencies while performing a manual task with low or high steadiness constraints. Results showed that high manual task constraint led to modulation of metric and coordination variables associated with greater postural stability. Our findings suggest that motor control is regulated in an integrative mode at the posturo-manual task level, with reciprocal interplay between the postural and manual components.
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Honami, S., T. Shizawa, A. Sato und H. Ogata. „Flow Behavior With an Oscillating Motion of the Impinging Jet in a Dump Diffuser Combustor“. Journal of Engineering for Gas Turbines and Power 118, Nr. 1 (01.01.1996): 65–71. http://dx.doi.org/10.1115/1.2816551.
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This paper presents flow behavior with an oscillating motion of an impinging jet upon a flame dome head and its reattachment to the casing wall, when a distorted flow is provided at the inlet of the dump diffuser combustor. A Laser-Doppler Velocimeter was used for the measurements of the time-averaged flow within a sudden expansion region. A surface pressure fluctuation survey on the flame dome head and flow visualization by a smoke wire technique with a high-speed video camera were conducted from the viewpoint of the unsteady flow features of the impinging jet. There exists a high-vorticity region at the jet boundary, resulting in the production of turbulence kinetic energy. In particular, higher vorticity is observed in the higher velocity side of the jet. The jet near the dome head has favorable characteristics about the flow rate distribution into the branched channel. Reynolds shear stress and turbulence energy are produced near the reattachment region. The jet has an oscillating motion near the dome head with asymmetric vortex formation at the jet boundary.
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Boeddeker, Norbert, und Jan M. Hemmi. „Visual gaze control during peering flight manoeuvres in honeybees“. Proceedings of the Royal Society B: Biological Sciences 277, Nr. 1685 (09.12.2009): 1209–17. http://dx.doi.org/10.1098/rspb.2009.1928.
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As animals travel through the environment, powerful reflexes help stabilize their gaze by actively maintaining head and eyes in a level orientation. Gaze stabilization reduces motion blur and prevents image rotations. It also assists in depth perception based on translational optic flow. Here we describe side-to-side flight manoeuvres in honeybees and investigate how the bees’ gaze is stabilized against rotations during these movements. We used high-speed video equipment to record flight paths and head movements in honeybees visiting a feeder. We show that during their approach, bees generate lateral movements with a median amplitude of about 20 mm. These movements occur with a frequency of up to 7 Hz and are generated by periodic roll movements of the thorax with amplitudes of up to ±60°. During such thorax roll oscillations, the head is held close to horizontal, thereby minimizing rotational optic flow. By having bees fly through an oscillating, patterned drum, we show that head stabilization is based mainly on visual motion cues. Bees exposed to a continuously rotating drum, however, hold their head fixed at an oblique angle. This result shows that although gaze stabilization is driven by visual motion cues, it is limited by other mechanisms, such as the dorsal light response or gravity reception.
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Gioanni, Henri, Annie Sansonetti und Mohamed Bennis. „Characteristics of cervico-ocular responses in the chameleon“. Visual Neuroscience 14, Nr. 6 (November 1997): 1175–84. http://dx.doi.org/10.1017/s095252380001186x.
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AbstractThe cervico-ocular reflex (COR) was investigated in the chameleon. Two kinds of responses were observed by oscillating the body (sine-wave stimuli) in the fixed-head animal: a "smooth response" of very low gain (around 0.08) and a saccadic response composed of 1–12 saccades per cycle of stimulation (depending on the stimulation frequency). Both responses were elicited in the compensatory direction (same direction as the stimulation) and exhibited a frequency dependence with low-pass properties. The saccadic response was especially developed and displayed a higher gain (up to 0.4) than the smooth response. In darkness, the saccades were triggered near the zero point (head-body alignment), whereas in the presence of a fixed visual surround they were elicited more regularly throughout the stimulation cycle. The amplitude of saccades was increased in the light. Consequently, the gain and the phase lag of the saccadic reponse were enhanced by the visual input. No visuo-cervical interaction was observed for the smooth response. Oscillating the body at a constant velocity (seesaw or ramp stimuli) revealed a frequency effect on the number of saccades (during a cycle of stimulation), but not on the gain of the response. Increasing the amplitude of oscillations augmented only very slightly the amplitude of saccades and consequently decreased the gain. Hence, the best working range of the saccadic response corresponds to body or head movements of low amplitude (up to ±20 deg) and low frequency (up to 0.25 Hz), and is improved by a visual input. These properties are discussed on a comparative point of view. It is proposed that, in chameleons, the saccadic response could contribute to gaze stabilization and add to the vestibulo-ocular and the optokinetic responses.
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Convertino, V. A., F. H. Previc, D. A. Ludwig und E. J. Engelken. „Effects of vestibular and oculomotor stimulation on responsiveness of the carotid-cardiac baroreflex“. American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 273, Nr. 2 (01.08.1997): R615—R622. http://dx.doi.org/10.1152/ajpregu.1997.273.2.r615.
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Twelve healthy men underwent measurement of their carotid-cardiac baroreflex response during varying conditions of vestibulo-oculomotor stimulation to test the hypothesis that vestibular and/or oculomotor stimulation associated with head movements in the yaw plane inhibit baroreflex control of heart rate. We assessed the carotid-cardiac baroreflex response by plotting R-R intervals (in milliseconds) at each of eight neck pressure steps with their respective carotid distending pressures (in millimeters mercury). Baroreflex sensitivity was measured under four experimental conditions: 1) sinusoidal whole body yaw rotation of the subject in the dark without visual fixation (combined vestibular-oculomotor stimulation); 2) yaw oscillation of the subject while tracking a small head-fixed light moving with the subject (vestibular stimulation without eye movements); 3) subject stationary while fixating on a small light oscillating in yaw at the same frequency, peak acceleration, and velocity as the chair (eye movements without vestibular stimulation); and 4) subject stationary in the dark (no eye or head motion). Head motion alone reduced baseline baroreflex responsiveness by 30% from 3.8 +/- 0.5 to 2.6 +/- 0.5 ms/mmHg. Eye motion alone also reduced the baroreflex response by 13% (0.5 ms/mmHg) to 3.3 +/- 0.5 ms/mmHg. During head motion, the effect of eye motion was negligible (2.7 +/- 0.4 ms/mmHg). These results suggest that vestibular stimulation associated with head movements in yaw inhibits vagally mediated baroreflex control of heart rate, whereas oculomotor stimulation is less of a factor and only in the absence of vestibular stimulation.
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Aoki, Reiko, Manabu Enoki und Ryo Yoshida. „Measurement of Elastic Properties of Self-Oscillating Gel“. Key Engineering Materials 321-323 (Oktober 2006): 1036–39. http://dx.doi.org/10.4028/www.scientific.net/kem.321-323.1036.
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Self-oscillating gel is designed by copolymerizing the catalyst for the Belousov- Zhabotinsky (BZ) reaction with thermosensitive polymer. The cylindrical-shaped specimens of NIPAAm-co-(Ru(bpy)3 gel were prepared by copolymerizing (Ru(bpy)3) monomer as catalyst with NIPAAm as thermosensitive polymer. Tensile tests were performed with cross-head speed of 10 )m/s in pure water at 20°C. Stress-strain curves were plotted using tensile load measured by semiconductor gauge and strains calculated from observation of the gel. Fracture strain and Young’s modulus were obtained from these curves. Also Poisson’s ratio was estimated from the ratio of strains in longitudinal and radial directions.
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Mark, Erwin P., Michael A. O. Lewis, Filippo Graziani, Boris Atlas und Joern Utsch. „Droplet Sizes Emitted from Demonstration Electric Toothbrushes“. International Journal of Environmental Research and Public Health 18, Nr. 5 (26.02.2021): 2320. http://dx.doi.org/10.3390/ijerph18052320.
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The COVID-19 pandemic has drawn attention to microbial transmission risk via aerosols in dental practice. Demonstration electric toothbrushes are used intra-orally for education. The aim of this investigation was to measure the size of droplets emitted by the brush head of two demonstration oscillating-rotating electric toothbrushes. Measurement of droplet production and size was recorded in vitro using three methods: (1) Malvern Spraytec (LASER particle size measurement device with detectable particle size of 0.1–2500 µm) and brushes mounted on a 3D-printed, two-shell form-fit fixture with a supply of tap water; (2) a DustTrak aerosol measurement device and toothpaste slurry, with brushing simulated in the oral cavity of a phantom head; (3) high-speed visualization in a simulated-use situation in the oral cavity of a phantom head, with individual evaluation of tap water, water with detergent, 70% ethanol, glycerin and toothpaste slurry. Both brushes showed the size of emitted droplets was consistently between 200 and 1200 µm, categorized as splatter (dental aerosols are <50 µm diameter). No significant incremental aerosol-sized matter was detected during toothbrush operation. The high-speed video visualization confirmed only splatter-sized droplets during operation. These findings indicate that oscillating-rotating toothbrushes do not produce aerosol-sized particles during simulated use.
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Cosson-Coche, Quentin, Olivier Cahuc, Philippe Darnis, Raynald Laheurte, Denis Teissandier und Didier Chabirand. „Experimental study on cutting flexible sheet materials using an oscillating knife“. International Journal of Clothing Science and Technology 29, Nr. 3 (05.06.2017): 349–65. http://dx.doi.org/10.1108/ijcst-05-2016-0058.
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Purpose The purpose of this paper is to understand the impact of the cutting forces on the quality of pieces in industrial cutting of multi-ply textile material. It also tries to establish a cutting model that can simulate the cutting forces in order to understand the behaviour of the blade. Design/methodology/approach Working on an industrial machine, a cutting head with an oscillating knife is instrumented with different sensors. Using this equipment, cutting forces can be analysed experimentally while the fabric is being cut along a straight line. Findings A model of the physical phenomena of the cutting forces is proposed, taking different parameters into account such as the geometry of the blade, the properties of the material being cut and the parameters of the cut. The simulated forces and the monitored forces are compared and parameters for minimising the cutting forces of fabrics are deduced. Research limitations/implications Due to the wide diversity of fabrics, all with different mechanical characteristics, this research only began with the study of denim in a straight cut. Originality/value This paper describes an instrumentation of automatic cutting head for textile. It manages to simulate the action of the fabrics on the blade through effort monitoring and help in the understanding of the multi-ply cutting process.
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Erbe, Christina, Collin Jacobs, Malgorzata Klukowska, Hans Timm, Julie Grender und Heinrich Wehrbein. „A randomized clinical trial to evaluate the plaque removal efficacy of an oscillating-rotating toothbrush versus a sonic toothbrush in orthodontic patients using digital imaging analysis of the anterior dentition“. Angle Orthodontist 89, Nr. 3 (05.12.2018): 385–90. http://dx.doi.org/10.2319/080317-520.1.
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ABSTRACT Objective: To compare the plaque removal efficacy of an oscillating-rotating electric toothbrush with an orthodontic brush head versus a sonic toothbrush in adolescent patients with fixed orthodontic appliances. Materials and Methods: This was a randomized, examiner-blind, replicate single-use, two-treatment, four-period, crossover study with a washout period between visits of approximately 24 hours. Forty-four adolescent patients with fixed orthodontic appliances in both arches were randomized based on a computer-generated randomization schedule to one of four toothbrush treatment sequences. The primary outcome was plaque score change from baseline, measured using digital plaque imaging analysis. Results: Baseline plaque levels for both brush treatments were high, covering more than 50% of the tooth area. Effective plaque removal was observed with both brush treatments (P < .001); however, the reduction in plaque with the oscillating-rotating toothbrush was statistically significantly greater (P = .017) compared with the sonic toothbrush. Conclusions: The study provides evidence for more effective plaque-removing efficacy of the oscillating-rotating toothbrush versus the sonic toothbrush among orthodontic patients.
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Fujiwara, T., Shinya Tsukamoto und M. Miyagawa. „Analysis of the Grinding Mechanism with Wheel Head Oscillating Type CNC Crankshaft Pin Grinder“. Key Engineering Materials 291-292 (August 2005): 163–70. http://dx.doi.org/10.4028/www.scientific.net/kem.291-292.163.
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In this study, the crankshaft pin grinding mechanism, which is carried out with wheel head oscillating type CNC crankshaft pin grinder, is theoretically analyzed. In order to maintain grinding process, the pin rotates and also rocks along wheel working surface, because the wheel head oscillates with journal rotation. Then, it is made clear that cylindrical plunge grinding process progresses in the pin grinding process for the first time. Therefore, grinding speed ratio, which is defined as ratio of substantial pin surface speed to wheel surface speed, is firstly formulated. Secondly, undeformed chip size generated by a grain is estimated with the grinding velocity ratio. Finally, the grinding performance is predicted with experimental equations, which obtained previous study. By this simulation, it is made clear that dimensional accuracy and also surface roughness vary on whole of the pin surface with constant journal rotation grinding method. On the contrary, deviations of both the dimensional accuracy and the surface roughness are reduced with controlled speed ratio grinding method, in which journal rotation speed is adequately controlled.
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Porter, Marianne E., Braden T. Ruddy und Stephen M. Kajiura. „Volitional Swimming Kinematics of Blacktip Sharks, Carcharhinus limbatus, in the Wild“. Drones 4, Nr. 4 (18.12.2020): 78. http://dx.doi.org/10.3390/drones4040078.
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Recent work showed that two species of hammerhead sharks operated as a double oscillating system, where frequency and amplitude differed in the anterior and posterior parts of the body. We hypothesized that a double oscillating system would be present in a large, volitionally swimming, conventionally shaped carcharhinid shark. Swimming kinematics analyses provide quantification to mechanistically examine swimming within and among species. Here, we quantify blacktip shark (Carcharhinus limbatus) volitional swimming kinematics under natural conditions to assess variation between anterior and posterior body regions and demonstrate the presence of a double oscillating system. We captured footage of 80 individual blacktips swimming in the wild using a DJI Phantom 4 Pro aerial drone. The widespread accessibility of aerial drone technology has allowed for greater observation of wild marine megafauna. We used Loggerpro motion tracking software to track five anatomical landmarks frame by frame to calculate tailbeat frequency, tailbeat amplitude, speed, and anterior/posterior variables: amplitude and frequency of the head and tail, and the body curvature measured as anterior and posterior flexion. We found significant increases in tailbeat frequency and amplitude with increasing swimming speed. Tailbeat frequency decreased and tailbeat amplitude increased as posterior flexion amplitude increased. We found significant differences between anterior and posterior amplitudes and frequencies, suggesting a double oscillating modality of wave propagation. These data support previous work that hypothesized the importance of a double oscillating system for increased sensory perception. These methods demonstrate the utility of quantifying swimming kinematics of wild animals through direct observation, with the potential to apply a biomechanical perspective to movement ecology paradigms.
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IMAI, Koki, Shintaro ITOH, Kenji FUKUZAWA, Yuya HAMAMOTO und Hedong ZHANG. „HDI-05 HIGH-SPEED TRIBOLOGICAL MEASUREMENT BY USING OSCILLATING OPTICAL FIBER PROBE(Head/Disk Interface and Tribology II,Technical Program of Oral Presentations)“. Proceedings of JSME-IIP/ASME-ISPS Joint Conference on Micromechatronics for Information and Precision Equipment : IIP/ISPS joint MIPE 2009 (2009): 109–10. http://dx.doi.org/10.1299/jsmemipe.2009.109.
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Zhu, Renchuan, Guoping Miao und Zhaowei Lin. „Numerical Research on FPSOs With Green Water Occurrence“. Journal of Ship Research 53, Nr. 01 (01.03.2009): 7–18. http://dx.doi.org/10.5957/jsr.2009.53.1.7.
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Green water loads on sailing ships or floating structures occur when an incoming wave significantly exceeds freeboard and water runs onto the deck. In this paper, numerical programs developed based on the platform of the commercial software Fluent were used to numerically model green water occurrence on floating structures exposed to waves. The phenomena of the fixed floating production, storage, and offloading unit (FPSO) model and oscillating vessels in head waves have been simulated and analyzed. For the oscillating floating body case, a combination idea is presented in which the motions of the FPSO are calculated by the potential theory in advance and computional fluid dynamics (CFD) tools are used to investigate the details of green water. A technique of dynamic mesh is introduced in a numerical wave tank to simulate the green water occurrence on the oscillating vessels in waves. Numerical results agree well with the corresponding experimental results regarding the wave heights on deck and green water impact loads; the two-dimensional fixed FPSO model case conducted by Greco (2001), and the three-dimensional oscillating vessel cases by Buchner (2002), respectively. The research presented here indicates that the present numerical scheme and method can be used to actually simulate the phenomenon of green water on deck, and to predict and analyze the impact forces on floating structures due to green water. This can be of great significance in further guiding ship design and optimization, especially in the strength design of ship bows.
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Dotlic, Milan, Boris Pokorni, Milenko Pusic und Milan Dimkic. „Non-linear multi-point flux approximation in the near-well region“. Filomat 32, Nr. 20 (2018): 6857–67. http://dx.doi.org/10.2298/fil1820857d.
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We consider non-linear multi-point flux approximations (MPFA) scheme for flow simulations in a model of anisotropic porous medium that includes wells. The hydraulic head varies logarithmically and its gradient changes rapidly in the well vicinity. Due to this strong non-linearity of the near-well flow, use of the MPFA scheme in the near well region results in a completely wrong total well flux and an inaccurate hydraulic head distribution. In this article we propose correction of the MPFA scheme. The outcome is a scheme that is second-order accurate even in the well vicinity for anisotropic medium. Solution obtained with this scheme respects minimum and maximum principle, and also, it is non-oscillating.
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Soutar, Anne, Monika Watt, John W. Cherrie und Anthony Seaton. „Comparison between a personal PM10 sampling head and the tapered element oscillating microbalance (TEOM) system“. Atmospheric Environment 33, Nr. 27 (November 1999): 4373–77. http://dx.doi.org/10.1016/s1352-2310(99)00227-7.
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Ishijima, Sumio. „Dynamics of flagellar force generated by a hyperactivated spermatozoon“. REPRODUCTION 142, Nr. 3 (September 2011): 409–15. http://dx.doi.org/10.1530/rep-10-0445.
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The flagellar force generated by a hyperactivated monkey spermatozoon was evaluated using the resistive force theory applied to the activated (nonhyperactivated) and hyperactivated flagellar waves that were obtained using high-speed video microscopy and digital image processing in order to clarify the mechanism of sperm penetration through the zona pellucida. No difference in the maximum propulsive force, which was parallel to the longitudinal sperm head axis, was found between the activated and hyperactivated spermatozoa. The maximum transverse force (45 pN), which was perpendicular to the longitudinal sperm head axis, of the hyperactivated spermatozoon was ∼2.5 times its propulsive force. As the beat frequency of the flagellar beating remarkably decreased during the hyperactivation, the slowly oscillating transverse force (5 Hz) by the hyperactivated spermatozoon seems to be most effective for sperm penetration through the zona pellucida.
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Ostermann, Florian, Rene Woszidlo, C. Navid Nayeri und C. Oliver Paschereit. „Properties of a sweeping jet emitted from a fluidic oscillator“. Journal of Fluid Mechanics 857 (22.10.2018): 216–38. http://dx.doi.org/10.1017/jfm.2018.739.
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This experimental study investigates the flow field and properties of a sweeping jet emitted from a fluidic oscillator into a quiescent environment. The aspect ratio of the outlet throat is 1. Stereoscopic particle image velocimetry is employed to measure the velocity field plane-by-plane. Simultaneously acquired pressure measurements provide a reference for phase correlating the individual planes yielding three-dimensional, time-resolved velocity information. Lagrangian and Eulerian visualization techniques illustrate the phase-averaged flow field. Circular head vortices, similar to the starting vortex of a steady jet, are formed repetitively when the jet is at its maximum deflection. The quantitative jet properties are determined from instantaneous velocity data using a cylindrical coordinate system that takes into account the changing deflection angle of the jet. The jet properties vary throughout the oscillation cycle. The maximum jet velocity decays much faster than that of a comparable steady jet indicating a higher momentum transfer to the environment. The entrainment rate of the spatially oscillating jet is larger than for a steady jet by a factor of 4. Most of the mass flow is entrained from the direction normal to the oscillation plane, which is accompanied by a significant increase in jet depth compared to a steady jet. The high entrainment rate results from the enlarged contact area between jet and ambient fluid due to the spatial oscillation. The jet’s total force exceeds that of an idealized steady jet by up to 30 %. The results are independent of the investigated oscillation frequencies in the range from 5 to 20 Hz.
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TOUCH, Narong, Shogo FUKUI, Shinya NAKASHITA, Shoji FUKUOKA und Tadashi HIBINO. „PERMEABILITY CHANGE OF SAND BEDS DUE TO SEDIMENT MIGRATION UNDER SEEPAGE FLOW WITH OSCILLATING WATER HEAD CONDITION“. Journal of Japan Society of Civil Engineers, Ser. B1 (Hydraulic Engineering) 69, Nr. 4 (2013): I_559—I_564. http://dx.doi.org/10.2208/jscejhe.69.i_559.
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De Nunzio, Alessandro M., Antonio Nardone und Marco Schieppati. „Head stabilization on a continuously oscillating platform: the effect of a proprioceptive disturbance on the balancing strategy“. Experimental Brain Research 165, Nr. 2 (26.04.2005): 261–72. http://dx.doi.org/10.1007/s00221-005-2297-7.
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Chapuis, Robert P. „The Physical Reasons to Have Underdamped or Oscillating Variable-Head (Slug) Tests: A Review and a Clarification“. Geotechnical Testing Journal 45, Nr. 1 (14.09.2021): 20210065. http://dx.doi.org/10.1520/gtj20210065.
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Pothier, David D., Cian Hughes, Wanda Dillon, Paul J. Ranalli und John A. Rutka. „The Use of Real-Time Image Stabilization and Augmented Reality Eyewear in the Treatment of Oscillopsia“. Otolaryngology–Head and Neck Surgery 146, Nr. 6 (18.01.2012): 966–71. http://dx.doi.org/10.1177/0194599811434708.
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Objectives/Hypothesis. The symptom of oscillopsia in patients with bilateral vestibular loss (BVL) can be reduced as dynamic visual acuity (DVA), the reduction in visual acuity during head movement, is improved by using real-time image stabilization, delivered by augmented reality eyewear. Setting. Tertiary multidisciplinary neurotology clinic. Study Design. Prospective experimental study. Methods. Immersive virtual reality glasses used in combination with a compact digital video camera were used. A software algorithm was developed that used a center-weighted Lucas-Kanade optical flow method to stabilize video in real time. Six patients with BVL were tested for changes in DVA using the eyewear. The ability to read a Snellen chart during a 2-Hz oscillating head rotation DVA test was measured. Results. For combined scores of vertical and horizontal head rotations, the mean number of lines readable at rest was 7.86, which dropped to 2.77 with head movement (a combination of vertical and horizontal perturbations). This increased to a mean of 6.14 lines with the image stabilization software being activated. This difference was statistically significant ( P < .001). Conclusion. This is the first successful attempt to improve dynamic visual acuity in patients with bilateral vestibular loss. Recent hardware upgrades are promising in improving these results even further.
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Zheng, L., J. L. Plawsky, P. C. Wayner, und S. DasGupta. „Stability and Oscillations in an Evaporating Corner Meniscus“. Journal of Heat Transfer 126, Nr. 2 (01.04.2004): 169–78. http://dx.doi.org/10.1115/1.1652046.
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A Constrained Vapor Bubble Loop Thermosyphon, CVBLT, made of quartz was used to study the stability and oscillations of an evaporating curved wetting film of pentane in a corner. The film thickness profile was measured as a function of heat input, time, and axial position using image analyzing interferometry. The curvatures and apparent contact angles for the evaporating film under various operating conditions were obtained from the measured film thickness profiles. Instability (oscillation) of the liquid film was observed at relatively higher values of the heat input. The behavior of the curvature and the apparent contact angle of an oscillating film with changes in heat input was evaluated. Moving velocities of the oscillating film were calculated from the measured values of the liquid-wall wetted lengths and were found to be directly proportional to the difference between the instantaneous force acting on the curved film and the reference force. Using an augmented Young-Laplace pressure jump model, the effect of the excess free energy at the contact line on the oscillations was demonstrated.
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Halisch, Christoph, Christof Gaßmann und Thomas Seefeld. „Investigating the Reproducibility of the Wire Arc Additive Manufacturing Process“. Advanced Materials Research 1161 (März 2021): 95–104. http://dx.doi.org/10.4028/www.scientific.net/amr.1161.95.
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Wire arc additive manufacturing (WAAM) of titanium parts shows promising potential for aerospace application due to its high deposition rates allowing a fast and economical production of large integral parts. However, due to the demands of aerospace industry an extensive qualification procedure is necessary to enable the parts as ready to fly. Nowadays, qualification for additive manufactured parts is a time-consuming process, so the advantages in additive manufacturing cannot be fully utilized. For this reason, a complete process qualification for WAAM would reduce the costs drastically in contrast to qualifying manufactured parts individually. As a first step the robustness and reproducibility of the energy reduced WAAM process was investigated. Thick-walled samples are manufactured layer by layer with an oscillating welding head motion. The mechanical properties of the samples are compared on an adequate statistical basis. Microstructural-and computer tomography analysis are conducted to comprehend shown interactions. The reproducibility is investigated in dependence of different heat treatment states, different directions of mechanical testing and two manufacturing systems of the same type.
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Tian, Xing, Jian Yang, Zhigang Guo und Qiuwang Wang. „Numerical Investigation of Gravity-Driven Granular Flow around the Vertical Plate: Effect of Pin-Fin and Oscillation on the Heat Transfer“. Energies 14, Nr. 8 (14.04.2021): 2187. http://dx.doi.org/10.3390/en14082187.
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In this paper, the heat transfer of pin-fin plate unit (PFPU) under static and oscillating conditions are numerically studied using the discrete element method (DEM). The flow and heat transfer characteristics of the PFPU with sinusoidal oscillation are investigated under the conditions of oscillating frequency of 0–10 Hz, amplitude of 0–5 mm and oscillating direction of Y and Z. The contact number, contact time, porosity and heat transfer coefficient under the above conditions are analyzed and compared with the smooth plate. The results show that the particle far away from the plate can transfer heat with the pin-fin of PFPU, and the oscillating PFPU can significantly increase the contact number and enhance the temperature diffusion and heat transfer. The heat transfer coefficient of PFPU increases with the increase of oscillating frequency and amplitude. When the PFPU oscillates along the Y direction with the amplitude of 1 mm and the frequency of 10 Hz, the heat transfer coefficient of PFPU is increased by 28% compared with that of the smooth plate. Compared with the oscillation along the Z direction, the oscillation along the Y direction has a significant enhancement on the heat transfer of PFPU.
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Van Gelder, Russell N., Helen Bae, Michael J. Palazzolo und Mark A. Krasnow. „Extent and character of circadian gene expression in Drosophila melanogaster: identification of twenty oscillating mRNAs in the fly head“. Current Biology 5, Nr. 12 (Dezember 1995): 1424–36. http://dx.doi.org/10.1016/s0960-9822(95)00280-6.
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Tan, Ek T., Robert Y. Shih, Jhimli Mitra, Tim Sprenger, Yihe Hua, Chitresh Bhushan, Matt A. Bernstein et al. „Oscillating diffusion‐encoding with a high gradient‐amplitude and high slew‐rate head‐only gradient for human brain imaging“. Magnetic Resonance in Medicine 84, Nr. 2 (03.02.2020): 950–65. http://dx.doi.org/10.1002/mrm.28180.
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Melkikh, A. V., und Yu E. Dolgirev. „Self-oscillations in oscillating heat pipes“. High Temperature 44, Nr. 4 (Juli 2006): 542–47. http://dx.doi.org/10.1007/s10740-006-0067-2.
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Jagtap, Harshal, und Uday Wankhede. „Experimental investigations of effect of sound waves on oscillation and startup characteristics of oscillating heat pipe at different orientations“. Thermal Science 21, Nr. 6 Part A (2017): 2587–97. http://dx.doi.org/10.2298/tsci150804142j.
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This research deals with the effects of working fluid and use of sound waves on the startup and heat transfer characteristics in terms of thermal resistance of a closed loop oscillating heat pipe. The performance of the oscillating heat pipe is checked for different orientations as 90? (vertical position), 60?, and 30?. Initially water is used as working fluid and performance of the oscillating heat pipe is checked with and without sound waves. Then 0.1 wt.% Al2O3-water nanofluid is utilized as working fluid in oscillating heat pipe and its performance is analyzed with and without sound waves. In this work, sound waves of 1 kHz frequency are passed through the evaporator section of closed-loop oscillation heat pipe. Application of sound waves improved the oscillation characteristics of the CLOHP with reduced startup time and enhanced thermal performance at all orientations. In comparison between working fluids, 0.1 wt.% Al2O3-water nanofluid showed better oscillation characteristics at all orientations of CLOHP except at 90? where use of sound waves leads to dry-out condition.
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Grau, Jan, Pavel Souček und Matěj Sulitka. „The Influence of Servo Drive Control on the NC Vertical Milling Machine Dynamic Compliance“. Journal of Manufacturing and Materials Processing 4, Nr. 4 (26.11.2020): 111. http://dx.doi.org/10.3390/jmmp4040111.
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A model Numerical Control (NC) machine tool dynamic compliance is analyzed, including the influence of its mechanical structure and position control feed drive algorithms. The dynamic model of the machine tool is divided into two main parts, which are closest to the machining process. First, the milling head assembly group is presented as a system of one mass oscillating in a 2D plane and 3D space. Second, the motion axes assembly group, XY cross table with linear feed drive, is presented. A square 2×2 dimension matrix of the total dynamic compliance is evaluated within the feed drive control system included. Partial elements of the mechanical structure dynamic compliance matrix of the general N×N dimension are contained in the total dynamic compliance matrix.
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EL BAROUDI, ADIL, und FULGENCE RAZAFIMAHERY. „THEORETICAL AND NUMERICAL INVESTIGATIONS OF FREQUENCY ANALYSIS OF TWO CIRCULAR CYLINDERS OSCILLATING IN A INCOMPRESSIBLE VISCOUS FLUID“. International Journal of Applied Mechanics 06, Nr. 05 (Oktober 2014): 1450049. http://dx.doi.org/10.1142/s1758825114500495.
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A potential flow is presented in this paper for the analysis of the fluid-structure interaction systems including, but not limited to, the idealized human head. The model considers a cerebro-spinal fluid (CSF) medium interacting with two solid domain. The fluid field is governed by the linearized Navier–Stokes equation. A potential technique is used to obtain a general solution for a problem. The method consists in solving analytically partial differential equations obtained from the linearized Navier–Stokes equation. From the solution, modal shapes and stokes cells are shown. In the analysis, the elastic skull model and the rigid skull model are presented. A finite element analysis is also used to check the validity of the present method. The results from the proposed method are in good agreement with numerical solutions. The effects of the fluid thickness is also investigated.
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Zalewski-Zaragoza, Robert Aureo, und Erik Scott Viirre. „Quantitative measurement of vertigo frequency: Preliminary results“. Journal of Vestibular Research 13, Nr. 1 (01.09.2003): 53–56. http://dx.doi.org/10.3233/ves-2003-13106.
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Persons who experience vertigo often describe their symptoms as a sensation of oscillations. Based on such a description, a pilot study was performed to determine if the frequency of the vertigo sensation could be quantified in a manner analogous to tone matching in tinnitus treatment. Fifteen subjects were tested using a virtual image system that consisted of a head mounted display showing a scene that oscillated horizontally or vertically at an adjustable frequency. Subjects were asked to adjust the direction and frequency to match their typical vertigo sensation. Results show that most persons with chronic vertigo had symptoms that could be realistically simulated by vection induced by the oscillating scene and that matched to a consistent specific frequency. They reported an average frequency of 1.09 Hz (range 0.27 to 3.3 Hz, SD 0.25). The large majority (13 out of 15) matched to a horizontal stimulus. Subjects that gave particularly high subjective ratings of the similarity of the motion sensation (7–8 out of 10) from the vection to their vertigo had lower frequency matches (average 0.61 +/- 0.25). Repeated measurements in 4 subjects 8 to 27 days later showed consistent results. This vertigo measurement technique may be used in the future to assess the ability of vestibular rehabilitation to reduce chronic vertigo. Identification of a specific frequency of chronic vertigo may be important in the specification of rehabilitation exercises.
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Van Dyke, Rufus O., Sejul A. Chaudhary, Gregory Gould, Roman Trimba und Richard T. Laughlin. „Biomechanical Head-to-Head Comparison of 2 Sutures and the Giftbox Versus Bunnell Techniques for Midsubstance Achilles Tendon Ruptures“. Orthopaedic Journal of Sports Medicine 5, Nr. 5 (01.05.2017): 232596711770747. http://dx.doi.org/10.1177/2325967117707477.
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Background: Acute midsubstance Achilles tendon ruptures are a common orthopaedic problem for which the optimal repair technique and suture type remain controversial. Head-to-head comparisons of current fixation constructs are needed to establish which stitch/suture combination is most biomechanically favorable. Hypothesis: Of the tested fixation constructs, Giftbox repairs with Fiberwire will exhibit superior stiffness and strength during biomechanical testing. Study Design: Controlled laboratory study. Methods: Two biomechanical trials were performed, isolating stitch technique and suture type, respectively. In trial 1, 12 transected fresh-frozen cadaveric Achilles tendon pairs were randomized to receive either the Giftbox-modified Krackow or the Bunnell stitch with No. 2 Fiberwire suture. Each repair underwent cyclic loading, oscillating between 10 and 100 N at 2 Hz for 1000 cycles, with repair gapping measured at 500 and 1000 cycles. Load-to-failure testing was then performed, and clinical and catastrophic failure values were recorded. In trial 2, 10 additional paired cadaveric Achilles tendons were randomized to receive a Giftbox repair with either No. 2 Fiberwire or No. 2 Ultrabraid. Testing and data collections protocols in trial 2 replicated those used in trial 1. Results: In trial 1, the Bunnell group had 2 failures during cyclic loading while the Giftbox had no failures. The mean tendon gapping after cyclic loading was significantly lower in the Giftbox repairs (0.13 vs 2.29 mm, P = .02). Giftbox repairs were significantly stiffer than Bunnell (47.5 vs 38.7 N/mm, P = .019) and showed more tendon elongation (5.9 ± 0.8 vs 4.5 ± 1.0 mm, P = .012) after 1000 cycles. Mean clinical load to failure was significantly higher for Giftbox repairs (373 vs 285 N, P = .02), while no significant difference in catastrophic load to failure was observed (mean, 379 vs 336 N; P = .61). In trial 2, there were no failures during cyclic loading. The Giftbox + Fiberwire repairs recorded higher clinical load-to-failure values compared with Giftbox + Ultrabraid (mean, 361 vs 239 N; P = .005). No other biomechanical differences were observed in trial 2. Conclusion: Simulated early rehabilitation biomechanical testing showed that Giftbox-modified Krackow Achilles repair technique with Fiberwire suture was stronger and more resistant to gap formation at the repair site than combinations that incorporated the Bunnell stitch or Ultrabraid suture. Clinical Relevance: A more in-depth understanding of the biomechanical properties of the Giftbox repair will help inform surgical decision making because stronger repairs are less likely to fail during accelerated postoperative rehabilitation.
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Atrushkevitch, V. G., V. N. Tsarev, L. U. Orekhova, L. A. Elizova und E. S. Loboda. „Comparative evaluation of the effectiveness in plaque removal from the tooth surface by electric toothbrushes with different types of bristle movement“. Stomatologist. Minsk, Nr. 4(31) (Dezember 2018): 58–63. http://dx.doi.org/10.32993/stomatologist.2018.4(31).11.
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Supportive periodontal therapy (SPT) is an important factor in maintaining the results of active treatment of periodontal disease. Selection of effective personal hygienic tools is very important in addition to the formation of sustainable hygienic skills in patients. The aim of the study is a comparative assessment of the quality of mechanical removal of a native microbial biofilm with toothbrushes with different types of head rotation and a manual toothbrush. Objects and methods. The extracted teeth were fixed in plaster models, and the vestibular surface of the three teeth was processed for 10 seconds without the use of toothpaste. Tooth № 1 was a control (biofilm was not removed), tooth № 2 was cleaned with a manual toothbrush with an imitation of the Brass method, tooth № 3 was cleaned with a brush with oscillating-rotating movements of bristles. Tooth №4 was brushed with a toothbrush with vibrating types of bristles motion. The enamel-cementum junction of the tooth was taken strictly from the vestibular surface along the central axis of the tooth for studying in a scanning electron microscope. Conclusions. A complete cleaning of the tooth enamel surface from microbial biofilms is not achieved after using a manual toothbrush. Toothbrushes with oscillating-rotating movements of bristles create the phenomenon of “sweeping” of the biofilm fragments into the area of the cementum-enamel junction. The vibrating types of bristles motion maximally clean the cervical area of the tooth.
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Ivanov, Ilya, Ivan Pleshcheev und Andrey Larkin. „Vibratory drilling with digital adaptive control“. MATEC Web of Conferences 224 (2018): 01047. http://dx.doi.org/10.1051/matecconf/201822401047.
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High standards and efficiency of deep hole drilling used for hard-to-machine metals and alloys could not be achieved if chips are not segmented in the cutting zone. Chip control could be achieved through transmission of harmonic vibrations to the drill in direction of its rotating axis. One way to maintain these vibrations is to replace a drill chuck with a special self-vibratory drilling head, which includes an elastic element that allows axial movement of the tool. The right stiffness value of an elastic element and appropriate machining conditions could lead to oscillation self-excitation of a drill due to the regenerative mechanism. It is advisable to support this mechanism with a control action defined within the feedback loop, which provides process quality necessary for chip control in the broad range of process parameters. This work analyzes adaptive control algorithm for vibratory drilling process dynamics where control action over an oscillating system is proportional to drill axial vibrational velocity, and a feedback gain is determined in the adaptation loop. Dynamics modeling of a closed-loop nonlinear system “elastic system-machining process-control system” is carried out for cases with or without control proving effectiveness of control algorithm. The model was used to analyze how control system analog-to-digital conversion parameters influence vibratory process quality. Requirements, which ensure control system achieves a control aim, were approximately stated for capacity and response limit for analog-to-digital conversion.
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Mair, Josef, Robert Canti, Roland Golle, Wolfram Volk und Hartmut Hoffmann. „Dynamic Strength Behaviour of Punch Connections in Shear Cutting Processes“. Key Engineering Materials 549 (April 2013): 262–69. http://dx.doi.org/10.4028/www.scientific.net/kem.549.262.
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Two basic types of load for the tool active elements can be distinguished for the shear cutting process of sheet metal. For high strength, brittle materials, the stamping punch will be exposed to distinctive oscillating axial dynamic loads as a result of abrupt released potential energy, from the tool active elements, the blanking tool and the stamping press, caused by a sudden cracking of the sheet. In contrast, when shear cutting ductile materials, sheet metal will be drawn into the die clearance and the resulting friction between the punch and the cut surface can cause high forces when pulling the punch out of the hole. When using punches featuring a complex cutting peripheral form, - not available as a standard part - it is necessary to decide between head and shank of the punch manufactured out of one part or a shaft without head, which is usually cheaper and can be manufactured by electro-erosive wire-cutting. In the second case, a linking element must be accepted, transferring the load transmission between shaft and tool. This linking element, realized by a form lock or traction, can be the reason for premature failure of the punch. The two described cases of load, in combination with lacking knowledge of the real load on the link as well as eligibility of different punch linking types for each case of loading, cause unnecessary cost in tool manufacturing by oversizing or punch fracture. For this, solid punches as well as joined punches with dowelled or screwed heads have been compared in systematic tests. Brazed and bonded punch heads have been involved in the test series as cost-efficient alternatives to custom punches. Collaterally, characteristic values have been determined for each type of punch in static and dynamic measurements. Especially impact absorption and stiffness of the connection represent non-destructive measureable values allowing a comparison of stamping punches in terms of their dynamic fatigue limit.
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Kunin, Mikhail, Yasuhiro Osaki, Bernard Cohen und Theodore Raphan. „Rotation Axes of the Head During Positioning, Head Shaking, and Locomotion“. Journal of Neurophysiology 98, Nr. 5 (November 2007): 3095–108. http://dx.doi.org/10.1152/jn.00764.2007.
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Static head orientations obey Donders’ law and are postulated to be rotations constrained by a Fick gimbal. Head oscillations can be voluntary or generated during natural locomotion. Whether the rotation axes of the voluntary oscillations or during locomotion are constrained by the same gimbal is unknown and is the subject of this study. Head orientation was monitored with an Optotrak (Northern Digital). Human subjects viewed visual targets wearing pin-hole goggles to achieve static head positions with the eyes centered in the orbit. Incremental rotation axes were determined for pitch and yaw by computing the velocity vectors during head oscillation and during locomotion at 1.5 m/s on a treadmill. Static head orientation could be described by a generalization of the Fick gimbal by having the axis of the second rotation rotate by a fraction, k, of the angle of the first rotation without a third rotation. We have designated this as a k-gimbal system. Incremental rotation axes for both pitch and yaw oscillations were functions of the pitch but not the yaw head positions. The pivot point for head oscillations was close to the midpoint of the interaural line. During locomotion, however, the pivot point was considerably lower. These findings are well explained by an implementation of the k-gimbal model, which has a rotation axis superimposed on a Fick-gimbal system. This could be realized physiologically by the head interface with the dens and occipital condyles during head oscillation with a contribution of the lower spine to pitch during locomotion.
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Xizhi, Ma, und Wang Gang. „Study on temperature rise in the screw pair under high frequent oscillation“. Industrial Lubrication and Tribology 68, Nr. 2 (14.03.2016): 197–205. http://dx.doi.org/10.1108/ilt-07-2015-0102.
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Purpose – This paper aims to study the mechanism of heat generation in a screw, and investigates the heat flux in the connection screw pair under high frequent oscillation along the axial direction. Heat generated in the screw under high frequent oscillation could be observed in a lot of situations and was significant, and it could cause damage of screw joining and transmission. Design/methodology/approach – A heat flux model in a screw pair under high frequent oscillation along the axial direction is established. Bulk temperature field in the connected parts is calculated by means of finite element methods. A testing device aimed to temperature rise measurement in a thread pair under high frequent oscillation is built. Temperature rises under different operation conditions are measured. Findings – The heat flux generated in the screw pair because of friction between the contact surfaces of the screw thread is obtained. The effects of oscillating amplitude and frequency on heat flux are obtained. It is found that amplitude and frequency have a significant influence on the heat generated under high frequent oscillation. The numerical results show good agreement with the numerical results. Research limitations/implications – This study has some limitations; for example, the friction coefficient and the relative sliding displacement between the thread surfaces need further accurate research. Practical implications – Heat generated in a screw under high frequent oscillation is very rarely mentioned in previous research papers. The methods used in this paper could be used to evaluate the heat flux and temperature under high frequent oscillations. The temperature could be used to calculate the thermal stress and expansion in the screw thread under high frequent oscillation. The screw connections need to be protected from the damage because of heat stress and from getting loose because of heat expansion of the connected parts. Originality/value – The mechanisms of heat generation in the screw pair under high frequent oscillation are studied. The model of heat flux in the screw under high frequency oscillation is established, and it could be used to calculate the heat flux under different operating conditions. The transient temperature field of the connected parts is given. A test facility was built and the experiment to measure the temperatures of the bolt and nut was carried out. The results had good agreement.
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Kondrachuk, A. V., S. P. Sirenko und R. Boyle. „Effect of difference of cupula and endolymph densities on the dynamics of semicircular canal“. Journal of Vestibular Research 18, Nr. 2-3 (26.12.2008): 69–88. http://dx.doi.org/10.3233/ves-2008-182-301.
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The effect of different densities of a cupula and endolymph on the dynamics of the semicircular canals is considered within the framework of a simplified one-dimensional mathematical model where the canal is approximated by a torus. If the densities are equal, the model is represented by Steinhausen's phenomenological equation. The difference of densities results in the complex dynamics of the cupulo-endolymphatic system, and leads to a dependence on the orientation of both the gravity vector relative to the canal plane and the axis of rotation, as well as on the distance between the axis of rotation and the center of the semicircular canal. Our analysis focused on two cases of canal stimulation: rotation with a constant velocity and a time-dependent (harmonically oscillating) angular velocity. Two types of spatial orientation of the axis of rotation, the axis of canal symmetry, and the vector of gravity were considered: i) the gravity vector and axis of rotation lie in the canal plane, and ii) the axis of rotation and gravity vector are normal to the canal plane. The difference of the cupula and endolymph densities reveals new features of cupula dynamics, for instance – a shift of the cupula to a new position of equilibrium that depends on the gravity vector and the parameters of head rotation, and the onset of cupula oscillations with multiple frequencies that results in the distortion of cupula dynamics relative to harmonic stimulation. Factors that might influence the density difference effects and the conditions under which these effects occur are discussed.
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de la Rubia, Ernesto, und Antonio Diaz-Estrella. „Natural Locomotion Based on Foot-Mounted Inertial Sensors in a Wireless Virtual Reality System“. Presence: Teleoperators and Virtual Environments 24, Nr. 4 (01.11.2015): 298–321. http://dx.doi.org/10.1162/pres_a_00236.
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Virtual reality has become a promising field in recent decades, and its potential now seems clearer than ever. With the development of handheld devices and wireless technologies, interest in virtual reality is also increasing. Therefore, there is an accompanying interest in inertial sensors, which can provide such advantages as small size and low cost. Such sensors can also operate wirelessly and be used in an increasing number of interactive applications. An example related to virtual reality is the ability to move naturally through virtual environments. This is the objective of the real-walking navigation technique, for which a number of advantages have previously been reported in terms of presence, object searching, and collision, among other concerns. In this article, we address the use of foot-mounted inertial sensors to achieve real-walking navigation in a wireless virtual reality system. First, an overall description of the problem is presented. Then, specific difficulties are identified, and a corresponding technique is proposed to overcome each: tracking of foot movements; determination of the user’s position; percentage estimation of the gait cycle, including oscillating movements of the head; stabilization of the velocity of the point of view; and synchronization of head and body yaw angles. Finally, a preliminary evaluation of the system is conducted in which data and comments from participants were collected.
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Jacob, Francois Dominique, Vijay Ramaswamy und Helly R. Goez. „Acquired Monocular Nystagmus as the Initial Presenting Sign of a Chiasmal Glioma“. Canadian Journal of Neurological Sciences / Journal Canadien des Sciences Neurologiques 37, Nr. 1 (Januar 2010): 96–97. http://dx.doi.org/10.1017/s0317167100009719.
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A 15-month-old male presented with a one-day history of acute onset, continuous oscillating movement of his right eye. He had received his one-year immunizations four days prior and had a four-day history of a febrile viral respiratory tract infection. Pregnancy was unremarkable. He had severe iron deficiency anemia (MCV 66, Hb 65) and was developmentally delayed, as he was unable to stand independently and was non-verbal. His head circumference was 49 cm (95th percentile) and his weight was at the 25th percentile. On physical examination, continuous horizontal large amplitude pendular nystagmus of the right eye at a frequency of 3-4 Hz was observed. No nystagmus was observed in the left eye, even on funduscopic examination. The child could fixate targets in all four quadrants with both eyes independently, and could fixate and track small objects with both eyes independently suggesting no significant visual field defect or visual loss. Dilated funduscopic examination was normal, extra ocular movements were full, pupils were equal and reactive and there was no relative afferent pupillary defect. The remainder of the neurological examination was normal. There was no head bobbing or anomalous head position and no stigmata of neurofibromatosis type 1. Magnetic resonance imaging of the brain (Figure) demonstrated a 2 cm x 1.6 cm x 1.2 cm suprasellar enhancing mass involving the optic chiasm, hypothalamus, mamillary bodies and superior pituitary stalk. There was no extension into the pituitary fossa or the optic nerves and no ventricular enlargement. A biopsy of the mass was obtained and revealed histology consistent with a low-grade pilocystic astrocytoma (World Health Organization (WHO) grade 1), consistent with a diagnosis of chiasmal glioma.