Effect Of High-frequency Vibration Research Articles

Effect of a Non-pharmacological Intervention on Vaccine-related Pain: Randomized Clinical Trial

BackgroundAcute pain during vaccine administration is an expected event; however, some strategies, such as the use of high frequency vibration devices associated with cryotherapy, may minimize it. AimEvaluate the effect of high frequency vibration associated with cryotherapy on the level of pain related to the administration of influenza vaccine by intramuscular route in adults. MethodA randomized clinical trial was conducted with 350 adults who received the influenza vaccine. Participants allocated to the intervention group used a high-frequency vibration device associated with cryotherapy during vaccination, and those in the control group administered the vaccine according to the service routine. ResultsMean self-reported pain after vaccination of participants who used the device was lower (1.5 ±1.7) when compared to those who did not use it (1.9 ±1.9) (p = .041). There was an association of higher levels of pain after vaccination with participants in the control group (p = .011), females (p = .042), with higher level of pain expected with vaccination (p < .001) and higher level of anxiety before (p < .001) and after vaccination (p = .001). ConclusionsThe use of high frequency vibration associated with cryotherapy has been shown to be a viable non-pharmacological intervention for the reduction of pain associated with influenza vaccination in adults.

Three-dimensional effect of high frequency vibration on convection in silicon melt

The effect of high-frequency vibrations with different orientations on the convective flow in a liquid metal inside a cubic cell heated from the side is investigated using the collocation spectral method. The vibration is in three dimensions with a vibration vector contained in one of the three principal planes of the cavity ($x\phantom{\rule{0}{0ex}}z$, $x\phantom{\rule{0}{0ex}}y$, and $y\phantom{\rule{0}{0ex}}z$ planes). In either weightlessness or gravity conditions, the influence of the vibrations on the flow is found to strongly depend on their direction: each vibration orientation has its own features and affects the flow intensity and pattern differently.

The Onset of Double-Diffusive Convection in a Two-Layer System With a Viscoelastic Fluid-Saturated Porous Medium Under High-Frequency Vibration

Abstract The effect of high frequency vibration in the gravity field on the double-diffusive convection in a two-layer system with a viscoelastic fluid-saturated porous layer is studied. The averaging method is employed to split the unknown functions into a periodic rapidly varying part and a slower mean part. Then, the governing equation of perturbations is numerically solved by the Chebyshev tau method and QZ decomposition method. The influence of physical parameters on the stability of system is investigated. It is shown that the neutral stability curves are bimodal under high frequency vibration. The parameter of the high frequency vibration mainly stabilizes the pure fluid layer for greater wave numbers and has a weak impact on the whole system for smaller wave numbers.

Effect of high frequency vibrations on PV silicon purification

Silicon purification for photovoltaic applications is a crucial challenge to improve the energy production performance of solar panels. In the present work, we focus on the metallurgical grade silicon purification process through a directional solidification technique, namely the horizontal Bridgman technique. By means of numerical simulations, it is shown that high frequency vibrations applied to the crucible can be used to enhance the convective level in the molten silicon (thermal-vibrational effect) and improve the purification of the final silicon ingot. The direction of the vibration, however, has to be carefully chosen, as it strongly influences the flow intensity and structure in the melt and can lead to multi-rolls and even reverse flows, with a direct effect on the induced purification.

Effects of High Frequency Vibration on the Expression of Osteogenic Genes in SAOS-2 and BMSCs:

Effects of High Frequency Vibration on the Expression of Osteogenic Genes in SAOS-2 and BMSCs:

Effects of High Frequency Vibration on the Surface Quality in Rotary Ultrasonic Machining of Glass BK7

Both rotary ultrasonic machining (RUM) and conventional grinding (CG) experiments were performed on the glass BK7 specimen to investigate the effects of high frequency vibration on the surface quality. The surface morphologies produced in the two machining processes were assessed and the associated material removal mechanisms were explored. Also, the influence of the spindle speed on the surface roughness was discussed. It was found that the mechanisms of the material removal involved in the RUM process were material pulverization and brittle fracture, while ductile flow and brittle fracture prevailed on the material removal in CG process. The increased spindle speed would reduce the lateral cutting depth of each abrasive, and promote the shielding effects of the lateral cracks generated by the previous abrasive, leading to the reduction of the surface roughness in both RUM and CG processes.

Effect of High Frequency Vibration on Pore Parameters and Frost Resistance of Air Entrained Concrete

High frequency vibration was brought to two different air-entrained concrete. Pore structure analyzer of hardened concrete quantitatively described the influence of vibration to air content, air spacing coefficient and bubble size distribution. Meanwhile, the relationship between high frequency vibration and the ability of frost resistance was accurately determined through the testing freeze-thaw cycle. The results showed that: long time high frequency vibration would cause decline of frost resistance.

Influence of high frequency vibration on deep drawing process of AZ31 sheet at room temperature

Quasi-ultrasonic vibration with a frequency of 15 kHz and a maximum output of 2 kW was imposed on the deep drawing process of AZ31 magnesium alloy sheet at room temperature, in order to reveal the effect of high frequency vibration on deformation behavior of AZ31 during the process. From the drawn results and the observation of the microstructure within the large deformation area, high frequency vibration has a great influence on the formability, the forming load and the failure mode of AZ31 sheet during the deep drawing process; the influence is a comprehensive result of so-called “volume effect” and “surface effect”, and relies on the vibrating amplitude. Total forming load decreased significantly as soon as the vibration superimposed. According to the tensile test results of AZ31 bars under ultrasonic vibration, the formability of AZ31 sheet increases firstly with the increase of stimulating energy, then decreases and finally becomes brittle. Under the combined influence of “surface effect” and the “softening” in the “volume effect” near the relative low amplitude of 25%A in the experiment (A is the maximum amplitude), the formability of AZ31 reaches the largest value, and the samples possess the same distribution trend of cracks as those added with lubricating oil. With the increase of excitation energy, the “volume effect” gradually becomes apparent, and finally the “hardening” of the “volume effect” occupies a dominant position.

Flexible flatfoot treatment in children with mechanical sound vibration therapy

Flatfoot is a common syndrome with multiple etiopathogenesis, that have long been associated with pain and disability, and very often worries parents for their children’s health and mobility. The generic term “flatfoot” describe any condition in which the longitudinal foot arch is abnormally low or absent usually associated with heel eversion and talar prominence. It is accepted that flatfeet are of different types. The most important classification considers two types, physiological flat foot and pathological flatfoot, with different prevalence and etiology. Although, many authors suggest that physiological flexible flatfoot usually does not cause disability and that asymptomatic children should not be burdened with inserts, a considerable number of arch supports are prescribed unnecessarily. An interesting and suggestive way to treat flatfoot with a conservative solution is to reduce structural alterations and symptoms increasing somatosensory input. The aim of the study was to improve the plantar arch proprioception information and muscles’ tone using high focal vibration therapy (300Hz). Recently, it was observed the possible involvement of the nervous system in modifications of muscle performance induced by vibration. In this study we evaluated the effects of high frequency vibrations applied on the skin of the feet in children affected by flexible flatfoot. Our data, obtained during quiet standing and during walking showed a significant reduction of Loading Surface of the Feet so we can affirm that VISS therapy may remit flexible flatfoot hypothesizing that postural control would improve after this treatment since somatosensory input from the lower limb has long been recognized as an important source of sensory information in controlling standing balance. Moreover, after vibratory stimulation of the mechanoreceptor on skin of the foot, we observed a significant increase in the strength of the muscles involved in maintaining posture and gait cycle. This makes us assume that these cutaneous receptors are specialized assuming, in addition to the classic role of exteroceptors, also the function of proprioceptors.

Effect of High-frequency Vibration on the Drawing Behavior of Staple Fiber Strands

This paper discusses fiber motion during roller drafting of staple fiber strands and its influence on the drafting force and drafting wave formation. It is well known that the dynamic friction coefficient of fibers is generally lower than the static friction coefficient, and the difference contributes to the “stick-slip” motion of fibers which causes the drafting waves in roller drafting. In this study a high-frequency vibration is introduced as a strand is attenuated in order to reduce the binding forces among fibers. Such reduction in drafting force is expected to improve strand uniformity by reducing the drafting waves. A roller drafting device capable of monitoring the strand drafting force has been designed and constructed. The experiments show that when a roving strand is subjected to lateral vibration, the force required to stretch the strand is significantly reduced. Average drafting force decreases with the increase in magnitude of the imposed vibration in the on-line drafting test. This study may lead to more efficient drafting systems for staple fiber processing.

Fundamental Study on the Effect of High-frequency Vibration in the Vertical and Lateral Directions on Ride Comfort

To develop a more suitable method of evaluating the ride comfort of railway vehicles, including high-speed trains, a fundamental study was conducted on passenger sensitivity to various frequencies of vibration with respect to ride comfort. Experiments were performed on 54 subjects using an electrodynamic vibration system that can generate vibrations in the frequency range of 1 to 80 Hz in the vertical and lateral directions. The results of the experiments indicated that the subjects tended to experience greater discomfort when exposed to high-frequency vibrations than presumed by Japan's conventional Ride Comfort Level assessment method.

Effect of High-Frequency Vibration on Convection in Miscible Fluids

The effect of high-frequency vibrations of the field of external mass forces on convection in miscible fluids is considered for a system of convection equations obtained by an averaging technique. The structures of flows formed under initial conditions corresponding to physical experiments in microgravity are examined.

Vibration influence on fluid interfaces

This work concerns the vibration influence on the stability and dynamics of fluid interfaces. Resonance phenomena (Faraday ripple, parametric waves under horizontal vibrations, the stability of the interface of liquid and its saturated vapor in the near critical state) are discussed. The thresholds of excitation of parametric resonance are determined and non-linear behavior is investigated. Mean effects of high frequency vibrations with various polarizations on the behavior of planar (terrestrial conditions) and cylindrical interfaces (space conditions) are analyzed. The shape and amplitude of the relief developing on the interfaces after stability loss are defined. The mechanisms of generation of mean flows near a fluid interface by high frequency vibrations are studied. To cite this article: D.V. Lyubimov et al., C. R. Mecanique 332 (2004).

Vibration energy absorption (VEA) in human fingers-hand-arm system

A methodology for measuring the vibration energy absorbed into the fingers and the palm exposed to vibration is proposed to study the distribution of the vibration energy absorption (VEA) in the fingers-hand-arm system and to explore its potential association with vibration-induced white finger (VWF). The study involved 12 adult male subjects, constant-velocity sinusoidal excitations at 10 different discrete frequencies in the range of 16–1000 Hz, and four different hand-handle coupling conditions (finger pull-only, hand grip-only, palm push-only, and combined grip and push). The results of the study suggest that the VEA into the fingers is considerably less than that into the palm at low frequencies (≤25 Hz). They are, however, comparable under the excitations in the 250–1000 Hz frequency range. The finger VEA at high frequencies (≥100 Hz) is practically independent of the hand-handle coupling condition. The coupling conditions affect the VEA into the fingers and the palm very differently. The finger VEA results suggest that the ISO standardized frequency weighting (ISO 5349-1, 2001) may underestimate the effect of high frequency vibration on vibration-induced finger disorders. The proposed method may provide new opportunities to examine VEA and its association with VWF and other types of vibration-induced disorders in the hand-arm system.

Modification of welding stresses by flexural vibration during welding

Flexural vibration was applied to specimens during the welding process to observe its effect on welding residual stresses. The study was carried out in three phases, namely, (i) investigation of the effect of amplitude of vibration, (ii) investigation of the effect of time of vibration, and (iii) investigation of the effect of high frequency vibration. The results of the present study provide a basis for relieving the residual stresses in practice. It has been shown that there is an optimum applied stress that will maximise the reduction in both longitudinal and transverse residual stresses. The effect of time of vibration on residual stresses was found to be negligible. After high frequency vibration, the change in longitudinal and transverse residual stresses showed no consistent trend.

Effect of High Frequency Vibration on Nerve Excitability

Effect of High Frequency Vibration on Nerve Excitability

Effects of high frequency vibration on critical Marangoni number

The influence of vibration on thermocapillary convection and critical Marangoni number in liquid bridge of half floating zone was discussed for the low frequency range 0.4–1.5 Hz and the intermediate frequency range 2.5–15 Hz in our previous papers. This paper extends the study to high frequency range 15–100Hz. This ground based experiment was completed on the deck of an electromagnetic vibration machine. The results of our experiment shows when the frequency of the applied acceleration is high enongh, the amplitude of the time varying part of the temperature response is disappear and the shape of the free surface of the liquid bridge exhibits no fluctuations due to inertia. The critical Marangoni number which is defined to describe the transitions from a peroidical convection in response to vibration to an oscillatory convection due to internal instability is nearly the same as the critical Marangoni number for oscillatory flow in the absence of vibration.

Effectofhigh-frequency vibration on filtration convection

Effectofhigh-frequency vibration on filtration convection

Effect of High-frequency Vibration on Experimental Pain Threshold in Young Women When Applied to Areas of Different Size

The purpose of this study was to compare the effects of high-frequency vibration when applied to two areas of different size. Subjects were 30 right-handed Caucasian women, aged 19-38 years, with a negative history of upper extremity dysfunction. The experimental cutaneous pain threshold was determined by stimulating the skin over the pisiform bone on the palmar surface of the hand. Pain threshold measurements were taken before, during, and 2 and 5 min after vibration. Group A received vibration to an area 12.5 cm2 on the ulnar aspect of the palm of the hand 1 cm distal to the pisiform bone. Group B received vibration to an area 25 cm2, also on the ulnar aspect of the palm of the hand. Results of the mixed design analysis of variance performed on the mean pain thresholds indicate that there was no significant main effect for group (size of area vibrated), p greater than 0.05, or interaction effect between group by trial (size of area vibrated and time of pain threshold measurement), p greater than 0.05. There was a significant main effect for trial (time of pain threshold measurement), p less than 0.001. Pain threshold values were greatest for both groups during the period of vibration.

Effect of high frequency vibration on convection initiation

In [1] equations are derived which describe convection in a gravity force field and a criterion is introduced which determines the onset of convection. In the present study we consider the case when, in addition to the gravity forces, there are vibrational forces acting on a liquid enclosed in a vessel. These forces arise as a result of vibration of the vessel along the vertical axis. In order to study the effect of vibrations we use the method of averaging with respect to small vibrations [2,3]. The unknowns are sought in the form of the sum of two terms, one which varies slowly with time and one of small amplitude which varies rapidly. Averaged convsction equations are formulated (§1). We consider the case of a plane horizontal strip and, under the assumption of satisfaction of the stability exchange principle, we introduce two parameters which define the onset of convection. One of these parameters is already known [1]—the product of the Grashof and Prandtl numbers. The second, arising as a result of the action of the vibrational forces, is apparently introduced here for the first time. The conclusions concerning the effect of vibrations on the initiation of convection (§3) are made for a model problem, on the assumption of spatially periodic disturbances (without accounting for the actual boundary conditions). In this case the vibrations stabilize the relative state of rest, and we can choose the velocity so that stability will exist for all temperature gradients A [see (3.7)]. It is found that in the presence of vibration (even small) the relative state of rest is stable with high temperature gradients. Moreover, if it is known that for given values of the vibration velocitya=a 0and the temperature gradient A=A0 the relative state of rest is stable, then we can, starting from the valuesa=0, A=0, by simultaneous variation ofa and A reach the indicated values (a 0, A0) while remaining in the region of stability. (We note that, generally speaking, the relative state of rest cannot be stabilized by simply increasing the gradient, since in the course of the increase the instability zone may be entered.) These conclusions are clearly valid only for vibrations with sufficiently high frequency which permit use of the averaging method. Justification of the method is not presented here. The study of the model problem gives an idea of the qualitative picture of the phenomenon. We would expect that the qualitative conclusions drawn are also valid under actual boundary conditions. The authors hope to carry out these calculations in the near future and present a justification for the proposed method.