Intermittent Vibration Research Articles

Mirror Visual Feedback Combining Vibrotactile Stimulation Promotes Embodiment Perception: An Electroencephalogram (EEG) Pilot Study.

As one determinant of the efficacy of mirror visual feedback (MVF) in neurorehabilitation, the embodiment perception needs to be sustainable and enhanced. This study explored integrating vibrotactile stimulation into MVF to promote the embodiment perception and provide evidence of the potential mechanism of MVF. In the experiment, the participants were instructed to keep their dominant hand still (static side), while open and close their non-dominant hand (active side) and concentrate on the image of the hand movement in the mirror. They were asked to tap the pedal with the foot of the active side once the embodiment perception is generated. A vibrotactile stimulator was attached on the hand of the active side, and three conditions were investigated: no vibration (NV), continuous vibration (CV), and intermittent vibration (IV). The effects were analyzed on both objective data, including latency time (LT) and electroencephalogram (EEG) signals, and subjective data, including embodiment questionnaire (EQ). Results of LT and EQ suggested a stronger subjective sense of embodiment under the condition of CV and IV, comparing with NV. No significant difference was found between CV and IV. EEG analysis showed that in the hemisphere of the static side, the desynchronization of CV and IV around the central-frontal region (C3 and F3) in the alpha band (8–13 Hz) was significantly prominent compared to NV, and in the hemisphere of the active side, the desynchronization of three conditions was similar. The network analysis of EEG data indicated that there was no significant difference in the efficiency of neural communication under the three conditions. These results demonstrated that MVF combined with vibrotactile stimulation could strengthen the embodiment perception with increases in motor cortical activation, which indicated an evidence-based protocol of MVF to facilitate the recovery of patients with stroke.

Effect of change of cross section and Frequency Analysis of Anti-Roll Bar Using FEA

Anti-roll bars are the suspension system component in automobiles that are used to control the body roll effect. They have a strong impact on the handling functions of the engine. The design effects of the anti-roll bar are normal in different vehicles and the study is mandatory for each design change. Finite Element Analysis (FEA) is used for an accurate study of the anti-roll bar style. The finite element analysis is carried out in ANSYS. The paper comprises of pre-processing, evaluating, post-processing, and using the work bench to interpret the FEA results. Be that as it may, because of a high number of rehashed plans looks at, deciphering time and cost issues related with the utilization of general FEA bundle projects may create critical inconveniences in utilizing these bundle projects to perform against move bar structure examination. Vibration characteristics such as typical set vibration levels and frequency are varied within the automotive environment. Even if an automobile is driven, the random excitations from road inputs and intermittent vibrations from engine firing are felt by its components and structures. It can sometimes cause problems with reliability if the construction of the components is often not completely evaluated.

Experimental investigation on defrosting of a cold flat plate via ultrasonic vibration under natural convection

The present experimental study examines the effect of ultrasonic vibration on the frost formation under a free convective environment. A stainless steel SS ANSI 316 flat surface is tested under 12–24 °C dry bulb temperature and 58–84% relative humidity. The experiments are conducted with direct contact and non-contact high-frequency ultrasonic source having continuous or intermittent vibrations. The ultrasonic transducer contains 28 ± 0.5 kHz resonance frequency. It is found that increasing the relative humidity will increase the frost thickness and influences the frost property. Imposing ultrasonic vibration under high relative humidity and low ambient temperature increases the droplets' circularity with comparatively sparse distribution. Test results indicate that non-contact vibration has no effect on the frost formation. Intensive intermittent contact vibration is the most effective way to suppress frost growth. Compared to continuous contact vibration, either it is applied after each an hour or after every 30 min as an intensive continuous, intensive intermittent contact vibration shows a reduction in frost thickness as much as 24%. In addition, the ultrasonic vibration should be applied after the supersaturation stage since ultrasonic vibration enhances the supercooled process.

An Improved Signal Pre-Processing Method for Gearbox Fault Features Extraction

Time synchronous averaging (TSA) has been extensively applied for gearbox fault analysis. But it cannot unveil the vibration features precisely in conditions of different speeds and load excitation. This paper presents an improved method which is a combination of Time synchronous averaging (TSA) and Empirical mode decomposition (EMD) to extract the intermittent vibration feature from the oscillated vibration response for the fault diagnosis of the gearbox. In this technique, time-synchronous averaging and empirical mode decomposition is performed on the gearbox vibration response to detect fault features. First, TSA is performed on the gearbox raw vibration response. By applying TSA on raw vibration response, a noiseless vibration response with the power spectrum is produced. Finally, decomposition technique is applied on noiseless vibration response and a sequence of IMFs are produced with the power spectrum to obtain more enhanced and improved mono-component of noiseless regular vibration response. Simulation and Practical investigation of the proposed method show the advantages and effectiveness in extracting faulty vibration feature with different speed and load excitation. An experimental investigation has been carried out on the Machinery Fault Simulator with one healthy and two faulty gearbox conditions i.e., healthy tooth, fragmented tooth and missing tooth under three different speed and load excitation.

A highly efficient and energy-saving magnetically induced membrane vibration system for harvesting microalgae

The optimal operational parameters of a second generation magnetically induced membrane vibration (MMV) system were determined using the response surface methodology (RSM) combined with single-factor experiments. The membrane surfaces were characterized by scanning electron microscopy (SEM) and algae cell states by inverted microscopy. The effect of an intermittent vibration strategy on filtration performance and energy consumption was studied. The results showed that the responses could be fitted by RSM models. High membrane flux, low energy consumption, efficient fouling control and no damage to the microalgae could thus be realized. The filtration strategy tests suggested that an intermittent cycle time of 4 min with 50% vibration rate could be the best vibration strategy for harvesting the microalgae under investigation.

Power Supply Switch Circuit for Intermittent Energy Harvesting

Energy harvesters generate power only when ambient energy is available, and power loss is significant when the harvester does not produce energy and its power management circuit is still turned on. This paper proposes a new high-efficiency power management circuit for intermittent vibration energy harvesting. The proposed circuit is unique in terms of autonomous power supply switch between harvester and storage device (battery), as well as self-start and control of the operation mode (between active and sleep modes). The self-start controller saves power during an inactive period and the impedance matching concept enables maximum power transfer to the storage device. The proposed circuit is prototyped and tested with an intermittent vibration energy harvester. Test results found that the daily energy consumption of the proposed circuit is smaller than that of the resistive matching circuit: 0.75 J less in sleep mode and 0.04 J less in active mode with self-start.

Finite Element Simulation Study of Ultrasonic Vibration-Assisted Tensile High-Volume Fraction SiCp/Al Composite.

Silicon carbide particle-reinforced aluminum matrix composite (SiCp/Al) has been widely used in the military and aerospace industry due to its special performance; however, there remain many problems in the processing. The present paper introduces an ultrasonic vibration tensile apparatus and a composite tensile specimen and performs Abaqus finite element simulation on high-volume SiCp/Al. The results show that the stress-strain curve increases linearly during conventional tensile strength; the intermittent vibration tensile strength is similar to the full course vibration tensile strength: The magnitude of the stress reduction increases as the amplitude of the ultrasound increases and the vibration frequency increases. The tensile rate is inversely proportional to the magnitude of the stress reduction, and in the ultrasonic parameters, the amplitude has the greatest influence on the magnitude of the stress reduction, followed by the tensile rate; additionally, the frequency has the least influence on the magnitude of the stress reduction. The experimental results show that the simulation results are consistent with the experimental results.

Effects of Local Vibration With Different Intermittent Durations on Skin Blood Flow Responses in Diabetic People.

Objective: Poor blood flow supply is an important pathological factor that leads to the development and deterioration of diabetic foot ulcers. This study aims to investigate the acute effects of local vibration with varying intermittent durations on the plantar skin blood flow (SBF) response in diabetic and healthy subjects.Methods: Eleven diabetic patients (7 males, 4 females) and 15 healthy adults (6 males, 9 females) participated in this experiment and accepted three tests. Local continuous vibration (LCV) and two levels of local intermittent vibration (LIV1 and LIV2) were randomly applied to the middle metatarsal head of each subject's right foot in each test. The SBF was measured prior to intervention (Baseline), during Vibration and during the Recovery Stage for each test. The mean SBF in each stage, the change percentages and change rates of SBF in Vibration and Recovery stage among three tests were compared and analyzed for both diabetic and healthy subjects.Results: For diabetic subjects, the SBF was significantly increased in both Vibration and Recovery Stage with local intermittent vibrations (LIV1 and LIV2), but not with LCV. However, there was no significant difference in change percentage and change rate of SBF in diabetic subjects across the three tests. For healthy subjects, all vibration interventions significantly increased the SBF in the Vibration Stage and in the first 1.5 min of the Recovery Stage. Also, the change rate of SBF during the Vibration stage in LIV1 test was significantly greater than that in LIV2 test for healthy subjects. Moreover, change percentage of SBF in Vibration stage of LIV1 test and in some periods of Recovery stages of LIV1 and LIV2 tests for diabetic subjects were lower than for healthy subjects; the absolute change rate of SBF in LIV1 test for diabetic subjects was also lower than for healthy subjects.Conclusion: These findings suggest that both LIV1 and LIV2 may effectively improve SBF in the feet of diabetic people, but LCV may not achieve the same level of vasodilatation. The diabetic subjects were also found to have a lower SBF response to applied vibration than the healthy subjects.

Effects of vibration on anammox-enriched biofilm in a high-loaded upflow reactor

An upflow biofilm reactor was operated for 211 days to investigate the effects of vibration on anammox treatment performance. With vibration, the highest nitrogen removal rates (20 kg-N·m−3·d−1) were obtained on day 180. Since the vibration could directly applied on the biofilm, it could release the dinitrogen gas accumulated in the biofilm timely and reduce the internal mass transfer resistance sharply. The specific anammox activity increased by more than 3 times with a higher vibration intensity. Meanwhile, the unique random motion caused by mechanical vibration promotes the production of extracellular proteins. Moreover, the VSS reached 20.97 g·L−1 which was 1.6 times higher than the control reactor. Such enrichment method resulted in a hard and thick anammox biofilm with a special granular morphology, and the nitrite tolerance concentration could reach 500 mg-N·L−1. Operated with an adequate vibration intensity could maintain the biofilm thickness and conducive to improve the stability of the reactor. In addition, this technique also allowed the microorganisms inside the biofilm and those on the surface to reach the same culture conditions. Base on the batch experiments, intermittent vibration caused a decrease in energy consumption from about 7.757 (kW·h)·(kg-N)−1 in group 0-Lv7(60-60) to 0.912 (kW·h)·(kg-N)−1 in group 0-Lv7(5-60). Compared to the internal recycle without vibration, the energy consumption fell by a slice over 65%. Furthermore, the high-throughput sequencing results showed that the relative abundance of Candidatus Kuenenia in reactor 1 increased from 13.2% to 43.9%.

Intermittent vibrations accelerate fracture healing in sheep.

Purpose:To investigate the effect of intermittent vibration at different intervals on bone fracture healing and optimize the vibration interval.Methods:Ninety sheep were randomized to receive no treatment (the control group), incision only (the sham control group), internal fixation with or without metatarsal fracture (the internal fixation group), and continuous vibration in addition to internal fixation of metatarsal fracture, or intermittent vibration at 1, 2, 3, 5, 7 and 17-day interval in addition to internal fixation of metatarsal fracture (the vibration group). Vibration was done at frequency F=35 Hz, acceleration a=0.25g, 15 min each time 2 weeks after bone fracture. Bone healing was evaluated by micro-CT scan, bone microstructure and mechanical compression of finite element simulation.Results:Intermittent vibration at 7-day interval significantly improved bone fracture healing grade. However, no significant changes on microstructure parameters and mechanical properties were observed among sheep receiving vibration at different intervals.Conclusions:Clinical healing effects should be the top concern. Quantitative analyses of bone microstructure and of finite element mechanics on the process of fracture healing need to be further investigated.

Effect of intermittent micro vibration stimulation on bone defect repair of ovariectomized mice

Effect of intermittent micro vibration stimulation on bone defect repair of ovariectomized mice

A self-cleaning piezoelectric PVDF membrane system for filtration of kaolin suspension

Exploring innovative membrane material is an important approach to mitigate membrane fouling. This study investigated a self-cleaning polyvinylidene fluoride (PVDF) piezoelectric membrane system which can vibrate at controlled frequencies, amplitudes and waveforms to mitigate membrane fouling. Among different PVDF films, the one of the highest content of β-phase PVDF was selected because of the greatest piezoelectric coefficient. The film was pin punched to 0.14 ± 0.02 mm holes for filtration purpose. The characteristic peaks of vibration velocity and amplitude were identified by measurements of a Scanning Laser-Doppler vibrometer with tiered driving voltages. The piezoelectric membrane was tested in a dead-end filtration system fed with 0.5 g L−1 kaolin suspension of 907.7 nm Z-average diameter at a constant filtration pressure of 34.5 kPa. The results indicate vibration velocity is more important than amplitude to choose the vibration frequency in order to optimize membrane fouling control. The piezoelectric membrane with continued vibration driven by 24 V (peak-to-peak) and sine wave at the frequency of 1601 Hz (the peak of vibration velocity) yielded 87 ± 3% higher permeate flux than control test, compared to 30 ± 3% increase at the frequency of 664 Hz (the peak of vibration amplitude). However, the antifouling effect was not apparent with intermittent vibration, possibly due to interrupted processes of cleaning and fouling prevention. The mechanistic explanation of cleaning suggests lift force brought by hydraulic shearing is more important than inertial lift force of vibration.

Activating the somatosensory system enhances net quadriceps moment during gait

Quadriceps muscle rehabilitation following knee injury or disease is often hampered by pain, proprioception deficits or instability associated with inhibition of quadriceps activation during walking. The cross-modal plasticity of the somatosensory system with common sensory pathways including pain, pressure and vibration offers a novel opportunity to enhance quadriceps function during walking. This study explores the effectiveness of an active knee brace that used intermittent cutaneous vibration during walking to enhance the peak knee flexion moment (KFM) during early stance phase as a surrogate for net quadriceps moment (balance between knee extensor and flexor muscle moments). The stimulus was turned on prior to heel strike and turned off at mid-stance of the gait cycle. Twenty-one subjects with knee pathologies known to inhibit quadriceps function were tested walking under three conditions: control (no brace), a passive brace, and an active brace. Findings show that compared to the control, subjects wearing an active brace during gait exhibited a significant (p < 0.001) increase in peak KFM and no significant difference when wearing a passive brace (p = 0.17). Furthermore, subjects with low KFM and knee flexion angle (KFA) in control exhibited the greatest increase in KFA at loading response in the active brace condition (R = 0.47, p < 0.05). Intermittent cutaneous stimulation during gait, therefore, provides an efficient method for increasing the KFM in patients with knee pathologies. This study’s results suggest that intermittent vibration stimulus can activate the cross-modalities of the somatosensory system in a manner that gates pain stimulus and possibly restores quadriceps function in patients with knee pain.

Spacer vibration for fouling control of submerged flat sheet membranes

Abstract In this study, a novel turbulence promoter based on vibrating spacers was investigated to control fouling in a submerged flat sheet membrane filtration system. The impacts of spacer types (1-D, 2-D, and 3-D), parallel distance of spacers to the membrane, vibration frequency and amplitude, and intermittent vibration interval on membrane fouling potential were examined. The results showed that vibration of 3-D spacers (sinusoidal geometry) could achieve up to 48% and 25% more fouling reduction than 1-D (flat plate) and 2-D (flat plate with grooves) spacers respectively when the spacers were located at a distance of 0.1 mm to the membrane. Increasing vibration frequency of the 3-D spacer from 1 to 2.5 Hz and increasing amplitude from 0.8 to 2 cm improved membrane fouling control efficiency by 33% and 34% respectively. The improved membrane performance was attributed to combined effects of the enhanced turbulence kinetic energy associated with back-transport of foulants and shear rate on the membrane surface as illustrated by the three-dimensional computational fluid dynamics (3-D CFD) simulations. An experimental and power consumption comparison of spacer vibration and gas sparging for fouling control was also performed. This study highlights the feasibility of vibration spacers in enhancing submerged flat sheet membrane performance.

Effects of tool intermittent vibration on helical internal hole processing in electrochemical machining

Ribbed holes can serve to increase the efficiency of the heat exchangers and improve the performance of industrial equipment. Increasing demand for small ribbed holes is a key driver in manufacturing technology research. Electrochemical machining has been shown to be a promising method for this. In this paper, an intermittent low-frequency vibration tool is used to demonstrate significant improvement to the geometry of internal ribbed holes. The process stability, material removal rates, and uniformity of features along the flow direction are improved. Firstly, a 3D model of the flow field within the interelectrode gap was developed to calculate and governing flow regime in the interelectrode gap. The simulation demonstrated that the fluid velocity fluctuates periodically and this enhances electrolyte flushing in the interelectrode gap during the machining process. Then, experimental tests for the manufacture of spiral ribs on small holes (Ø1.5 mm and 20–40 mm depth) are also demonstrated with accompanying variation of the tool vibration amplitude and frequency, respectively. Results show that groove depth was most greatly influenced by the vibration amplitude and that better uniformity could be obtained at higher vibration frequencies. The groove depth increased by 15% over nonvibrating control tests with enhanced uniformity.

Effects of ultrasonic vibration on the compression of pure titanium

The technology of ultrasonic vibration assisted plastic forming possesses a great many merits, such as reducing the deformation resistance and friction, as well as improving the surface quality of parts. In this study, the ultrasonic vibration assisted compression tests were carried out on pure titanium in order to improve its formability. The results indicating that the ultrasonic vibration had no effort on elastic deformation, and the temperature of material only increased by 6 °C after compression with applying the ultrasonic vibration. Therefore the influence of temperature increase on reduction of flow stress could be ignored. After excluding interface friction and temperature effects, ultrasonic vibration can still decline the flow stress, the mechanism of deformation includes ultrasonic softening, stress superposition and strain hardening. In the intermittent vibration tests, the material shows the residual softening effect after stopping vibration. By observing the microstructure of material with SEM, it shows that the ultrasonic vibration can promote the generation of deformation twins, causing the grain refinement and the reduction of the twins, which is the major factor of affecting the residual softening effect.

Intermittent ultrasonic wave to improve oil recovery

This paper presents the use of intermittent vibration as a cost-effective and environmentally friendly approach to enhance oil recovery (EOR). Previous research work has focused only on continuous ultrasonic vibration, but the continuous vibration has its limitation of the high cost of the production and maintenance of equipment because of the high energy generated. For this purpose, a 2D micro-model placed inside an ultrasonic bath under an ultrasound vibration was used to determine the effect of viscosity, intensity and the distance between the energy source and the micro-model. Dimensionless parameters were used to reduce the number of parameters to be studied by scaling the miscible and immiscible displacement in the porous media and to predict the fluid flow pattern. A stereo microscope with the camera mounted at the top of the micro-model recorded the displacement process. The snapshot of each time interval was used to give the estimate in percent (%) of the residual oil left in the micro-model. The outcome reveals that the use of intermittent vibration can recover more oil compared with the application using continuous vibration. The oil recovery increased with increase in the dimensionless parameters. The Reynold's number indicated that the flow was dominated by a laminar flow. The combination of intermittent vibration, high viscosity, high intensity and a short distance from the energy source gave the best recovery of oil.

Can cutaneous vibration affect pain development? Testing the efficacy of a vibrating belt applied intermittently to the low back region during prolonged standing

Standing-induced low back pain (LBP) is becoming more common in the workplace and has been shown to develop in periods of as short as 2 h. The purpose of this study was to determine if vibration, an increasingly popular method of pain relief, applied intermittently (every 15 min) directly to the low back could alleviate pain developed during a 2-h period of standing. Two separate collection days were conducted (order randomized). During the control day, no vibration was applied during the 2 h of standing; on an experimental day, vibration was applied via a vibration belt in 3-min durations every 15 min for 2 h. During both data collections, perceived LBP was collected via a visual analogue scale every 15 min; on the experimental day LBP was collected just prior to and following each vibration bout. Force plate data were also collected to determine centre of pressure changed over time. LBP significantly increased over time on both collection days; however, on the vibration day LBP reported just prior to each vibration bout was significantly higher than that immediately following, suggesting a temporary relief of pain. However, this relief of pain was not sustained as the level of perceived LBP at the end of the 2 h on the control day was not significantly different from that on the vibration day. Decreases in anterior-posterior and medial-lateral centre of pressure movement were also observed during each bout of vibration compared to during the control day. In conclusion, while intermittent vibration applied to the low back appears to relieve LBP developed during standing, this relief is temporary.

Effects of continuous or intermittent low-magnitude high-frequency vibration on fracture healing in sheep.

Vibration therapy has been shown to improve fracture healing. In this study, we investigated the effects of continuous or different intermittent vibration regimens on fracture healing in sheep models on the basis of radiographs, mechanical, and biochemical testing. The 63 right-hind metatarsals from 63 sheep (12-month-old) were osteotomized; followed by surgical fixation with a steel plate. Two weeks after the surgery, the sheep with right-hind metatarsal fractures were randomly divided into seven groups (n=9/group): control (no vibration treated), continuous vibration (CV), one, three, five, seven and 14-day intermittent vibration (named IV-1, -3, -5, -7, and -14, respectively) groups, which represented a cycle of the successive n-day vibration and successive n-day break. Vibration stimulation (F=35 Hz, a=0.25 g) lasted 15 minutes each treatment. After eight weeks with/without vibration treatment, the sheep were euthanized with intravenous anesthetic. The callus formation, mechanical properties, and biochemical compositions of fracture metatarsals were analyzed. In CV and IV-7 groups, X-ray images showed an increased callus volume around the fracture area. The bone elastic modulus and the concentrations of Ca, P, and Ca/P ratio of the area at 15 and 25 mm away from the fracture centerline were higher in CV and IV-7 groups compared with the other groups. Our results demonstrate that both CV and IV-7 vibration patterns showed better improvement of fracture healing.

Performance of surfactant-polymer flooding under the influence of intermittent ultrasonic waves

The main focus of this research is to initiate the use of intermittent vibration in order to save the cost. Mechanical vibrations generated by ultrasonic radiation influence interfacial forces and increase the relative permeability of the phases. In this project, ultrasonic vibration was designed to assist surfactant-polymer (SP) flooding process for more significant effects, as SP flooding is one of EOR methods that is able to maximize both sweep and displacement efficiency. Besides, this work has been designed to understand the mechanics of intermittent ultrasonic vibration in influencing additional recovery of SP flooding, reduction of residual oil saturation, and displacement pattern at pore scale during the flooding process under exposure of ultrasonic waves. To achieve this, experiments consisting of visualization (at pore scale) and displacement experiments were conducted. Ultrasonic power was changed to see the influence on the process. Residual oil saturation at end of the flooding was recorded and snapshots of oil displacement were taken. The outcomes justified that intermittent vibrations can produce and enhance more additional oil recovery of SP flooding compared to the continuous vibration, and the reduction of residual oil saturation, and oil displacement rate highly dependent on the ultrasonic power.