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Collaboration of scientists from different countries is a crucial tool for the development of science. Today’s pandemic initiates the integration of the ideas of scientists around the world to study and combat the aggressive pathogen COVID-19. Under current circumstances, we are losing informal communication as one of the essential aspects of scientific progress. This situation seriously changes the paradigm of the development of scientific thought, reducing communication to formal things. Scientific discoveries occur just when thought goes beyond the framework. Thus, the pandemic poses a comprehensive threat to society. To date, the uncontrolled situation of the pandemic is associated with a multifaceted behavioral factor of the virus. The virus acts differently on different continents of the planet and within the same geographical area, which makes its symptoms somewhat arbitrary. This pushes to an entirely new, information-wave level of understanding of the virus. The penetration of virions into the cell is the transfer of information, in this case, foreign to it and damaging. The interaction of the “virtual signal” with the “information receiver” is evident, and the virion itself is considered a virtual genetic signal, which becomes real only when received by a cell with an adequate code. The nature of the information contained in viruses is essential for determining the formation of diseases. These may be purely functional disorders, inflammatory (regardless of their location), or other processes. All of the above is determined based on the vibration frequencies of the virus–organism system. Viruses, like other biological objects, are characterized by both systemic biological properties and purely physical ones. If we consider the human body from the standpoint of physical properties, there is no division between the body’s internal environment and the external one. There is a single environment engulfed in cyclic, oscillatory processes, the characteristics of which are the same everywhere: in a person, in the movement of planets, on the Sun, and in interplanetary space. Throughout evolutionary history, both the virus and the organism are formed based on mutual environmental fluctuations. The formation of a specific oscillatory system, based on general physical considerations, ends when the oscillations of all system components are coordinated with each other. Thus, having information about the vibration frequencies of viral fragments, we can artificially select such a protein, the vibration frequency of which corresponds to the rhythm of the virus fragment. Such a protein could bind to the virus, preventing it from infecting healthy cells.

Myoelectric prosthesis has become an important aid to disabled people. Although it can help people to recover to a nearly normal life, whether they can adapt to severe working conditions is a subject that is yet to be studied. Generally speaking, the working environment is dominated by vibration. This paper takes the gripping action as its research object, and focuses on the identification of grasping intentions under different vibration frequencies in different working conditions. In this way, the possibility of the disabled people who wear myoelectric prosthesis to work in various vibration environment is studied. In this paper, an experimental test platform capable of simulating 0–50 Hz vibration was established, and the Surface Electromyography (sEMG) signals of the human arm in the open and grasping states were obtained through the MP160 physiological record analysis system. Considering the reliability of human intention recognition and the rapidity of algorithm processing, six different time-domain features and the Linear Discriminant Analysis (LDA) classifier were selected as the sEMG signal feature extraction and recognition algorithms in this paper. When two kinds of features, Zero Crossing (ZC) and Root Mean Square (RMS), were used as input, the accuracy of LDA algorithm can reach 96.9%. When three features, RMS, Minimum Value (MIN), and Variance (VAR), were used as inputs, the accuracy of the LDA algorithm can reach 98.0%. When the six features were used as inputs, the accuracy of the LDA algorithm reached 98.4%. In the analysis of different vibration frequencies, it was found that when the vibration frequency reached 20 Hz, the average accuracy of the LDA algorithm in recognizing actions was low, while at 0 Hz, 40 Hz and 50 Hz, the average accuracy was relatively high. This is of great significance in guiding disabled people to work in a vibration environment in the future.

Monitoring the dynamic responses of bridge structures has received considerable attention. It is important to synchronously measure both the quasi-static and dynamic displacements of bridge structures. However, the traditional accelerometer method cannot capture the quasi-static displacement component, although it can detect the dynamic displacement component. To this end, a novel composite instrument of a smartstation was proposed to monitor vibration displacements of footbridges. Full-scale experiments were conducted on a footbridge to validate the feasibility of the composite instrument-based monitoring method. A Chebyshev filter and wavelet algorithms were developed to process the composite instrument measurements. It was concluded that the measurement noise of the composite instrument was mainly distributed in a frequency range of 0–0.1 Hz. In two case studies with displacement peaks of 5.7–10.0 mm and 1.3– 2.5 mm, the composite instrument accurately identified the quasi-static and dynamic displacements. The composite instrument will be a potential tool for monitoring structural dynamics because of its enhanced overall performance.

An N1 vehicle model is created, which allows for changing suspension parameters and conditions of experimental performance. A methodology of computer testing performance for vehicle ride comfort and stability service properties’ characterization in a virtual environment is proposed. Vehicle suspension system modelling and simulation are performed. The results of the N1 vehicle suspension system from full-scale laboratory and road tests are given.

This paper proposes simplified formulations for estimating the main frequencies of ancient masonry churches. The formulations are derived starting from the results of numerical analyses with finite elements models, whose geometric parameters are assigned in accordance with specific relationships established on a set of 50 existing churches. The so-obtained formulations are also compared with the results of a series of experimental dynamic identification tests chosen from literature. Finally, starting from these experimental results, through numerical regressions, formulas for predicting the main frequencies of ancient masonry churches are proposed, too., The research activity carried out by SL has been supported by the ELARCH scholarship and mobility, a project funded under the Erasmus Mundus Action 2 Partnership (EMA2) by the European Commission, and coordinated by the University of Basilicata (www.elarch.org). ELARCH project: Reference number 552129-EM-1-2014-1-IT-ERA MUNDUS-EMA21 funded with support of the European Commission. This document reflects the view only of the author, and the Commission cannot be held responsible for any use which may be made of the information contained therein.

Focal vibration therapy can provide neurophysiological benefits. Unfortunately, standardized protocols are non-existent. Previous research presents a wide range of protocols with a wide range of effectiveness. This paper is part of a broader effort to identify effective, standardized protocols for focal vibration therapy. In this study, the authors evaluated the vibration characteristics (frequency and peak-to-peak intensity) of four commercially available focal vibration devices: (1) Vibracool (wearable), (2) Novafon (hand-held), (3) Myovolt 3-actuator (wearable), and (4) Myovolt 2-actuator (wearable). An accelerometer was used for the measurements. Measurements were made under the following two conditions: (a) when the devices were free, i.e., unconstrained vibration, and (b) when the devices were strapped to the human body, i.e., constrained vibration. In the free vibration condition, frequency ranged from 120 to 225 Hz and peak-to-peak amplitude ranged from 2.0 to 7.9 g’s. When the devices were strapped to the body (constrained), vibration amplitude decreased by up to 65.7%. These results identify effective ranges of focal vibration frequency and amplitude. They illustrate the importance of identifying vibration environment, free or constrained, when quoting vibration characteristics. Finally, the inconsistency output of multi-actuator devices is discussed. These results will guide protocol development for focal vibration and potentially better focal vibration devices.

In order to study the effect of the operational loads on the ground-borne vibration of the high-speed train, a train-track coupling model with considering the vertical and horizontal effects is established and applied to calculate the impact of different operational speeds on vibration acceleration. As shown in the results, the vibration acceleration is largely affected by different frequencies generated from different train speeds. By means of an indoor dynamic triaxial test, the impact of different vibration frequencies of a train on soil body is simulated. And a large number of medium- and low-frequency vibration tests are conducted according to the settings of load form, drainage requirement and vibration number of train vibration loads. The experimental results are analyzed to study the effect of different frequencies on dynamic characteristics, and a dynamic strain-time calculation formula, that takes the frequency factor into consideration, is proposed. Meanwhile, the improved formula that considered frequency is substituted into the finite element model (FEM) of the train, so as to analyze the impact of different vibration frequencies on the settlement, is applied. As shown in the results, the proposed improved formula, that considered the frequency, is good at prediction. The effect of vibration efficiency on the engineering can be reflected by a simulated high-speed train model. Based on the simulation model, a reinforcement measure is conducted for the ground-borne, and it is calculated that the settlement is obviously reduced and the service time of the train ground-borne is increased. This paper can provide a reference for a theoretical research and engineering practice.

In this review, we present a narrative synthesis of studies on the use of focal muscle vibration (FMV) in stroke rehabilitation with a focus on vibration device, parameters, and protocols. A search was conducted via PubMed, SCOPUS, PEDro, REHABDATA, and Web of Science using the keywords “stroke and focal vibration” or “focal muscle vibration”. Inclusion and exclusion criteria to select the articles were determined. Twenty-two articles involving FMV and stroke were included in this review. Eight different vibration devices were used in the 19 articles that reported the vibration apparatuses. The vibration frequencies ranged from 30 Hz to 300 Hz with amplitudes ranging from 0.01 mm to 2 mm. The vibration treatment frequency ranged from a single treatment to 5 days/week. The session duration ranged from 14 s to 60 min/session with a duration of a single treatment to eight weeks. Twenty different muscles were targeted with 37 different outcome measures used to assess the effects of FMV. The clinical applications of FMV were not confirmed based on available evidence. More research is needed to improve the FMV technology, guide the selection of vibration parameters, optimize the vibration dosage, and develop standardized protocols for FMV therapy in patients with stroke.

The study of ultrasonic atomization is one of the important factors for fuel spray process in the diesel engine combustion chamber. The droplet characteristics are influenced by liquid properties and vibration frequency. In this study, the phenomenon of droplet formation and droplet size were studied at different frequencies of the ultrasonic atomization processes for water liquid. The ultrasonic atomizer was used for the atomization process to generate droplets. CFD- 2D with the Volume of Fluid (VOF) model was used to study the process of droplet size and droplet formation at different frequencies. Water with constant film thickness and bending vibration at constant vibration amplitude were used in this model. The variation of vibration frequencies is applied from 50 kHz to 200 kHz with 50 kHz increment. The results showed that the number of droplets and the area of droplet formation increases with the increases in the vibration frequency. Effect of vibration frequency to the size of the droplet, time for droplet formation, velocity, and several droplets is more significant at vibration frequency 50 kHz to 100 kHz than vibration frequency from 100 kHz to 200 kHz.

International audience; Due to repetitive micro-displacements, the fretting phenomenon was defined as an electrical and mechanical degradation of the electrical contact interface in automotive sensors. Commonly, the electrical degradation was quantified by the increase of contact resistance deduced from the contact voltage. This work aims to address the analysis of relative displacements according to three space directions between sensor components in contact for different vibration frequencies for a Top Dead Center sensor. Particular attention was paid to measurements of displacements near crimping zones. © 2019, Springer International Publishing AG, part of Springer Nature.

The technique of vibration-induced illusory movement has been used to study the mechanisms of perception and the brain network responsible for eliciting kinesthesia since it was first reported by Goodwin and colleagues in 1972. Vibration applied to the skin surface over the tendon of limb muscles excites primary afferent spindles, and subjects experience movement sensations as if the vibrated muscle were stretched, despite the limb being immobile. In addition, tendon vibration can induce tonic muscle activities in both the vibrated muscle and its antagonistic muscles. It was formerly believed that these motor responses accompanied the kinesthetic illusion of the vibrated limb. However, if subjects relax their limb completely and focus their attention on the movement sensed during vibration, a movement illusion can be elicited without any motor responses. This review focuses on the relationship between the elicitation of vibration-induced kinesthetic illusions and experimental conditions, and may provide insight into differences among studies of kinesthetic illusion.

The paper presents the results of experimental research conducted on the newly constructed post-tensioned pre-stressed concrete road bridge situated over water plant of water reservoir under dynamic field load tests in Topola village (Poland). The dynamic loads consist of four heavy trucks passing at different speeds, through threshold and braking at the midspan. The obtained results from field load tests and the calculation of dynamic coefficients, values of amplitudes of vibration velocities and frequencies of two bridge spans have allowed to assessment of effectiveness of structural solutions applied at this bridge and establish some guidelines for using of this type of construction process in design structural solutions located over water plants in the future engineering practice. Wide range of conducted dynamic tests have allowed for comprehensive evaluation of the concrete elements effort of bridge structure. Final conclusions confirmed the observations taken from the research under static load.

Sonic drill rig can obtain good drilling and sampling effects in sand gravel layer with high-frequency vibration and low speed rotation of the power head. The drilling speed of sonic drill is five times than traditional rotary drilling method. Meanwhile, it does not need slurry to protect wall of borehole during drilling, so it has the following advantages: good fidelity of rock and soil samples and less environmental pollution. As a consequence, it has a good application prospect in the exploration of hydropower station, environmental protection drilling and other fields. In the paper, combining drilling experiment of domestic sonic drill rig YGL-S100 in Xiangjiaba hydropower station, the influence of sonic drill's vibration frequency on rock fragmentation effect and the reasonable choice of drilling technology had been researched and analyzed. Further, improving the sonic drill properties and optimizing drilling technology parameter were carried out.

The vibration characteristics of stiffened plates with cutouts subjected to in-plane partial edge loadings at one end at the plate boundaries are studied using the finite element method. Buckling loads and vibration frequencies are determined for different cutout ratios and extent of partial edge loading at one end. In the structural modelling, the plate and the stiffeners are treated as separate elements where the compatibility between these two types of elements is maintained. The main elegance of the formulation lies in the treatment of the stiffeners. The stiffeners can be placed anywhere within the plate element, and need not be placed on the nodal lines. The vibration characteristics are discussed and the results are compared with those available in the literature. Numerical results are presented for a range of cutout to plate size from 0 to 0.8.

Anew version of a steeply inclined pivoted bucket belt conveyor with slippage of the traction belts relative to the shells of the reels is proposed. The natural vibrations of the buckets in the course of travel, taking into account the total rigidity of the two joined belts and the planks clamped between them, are estimated. The resonant speed of the conveyor belts is determined and the coefficient of dynamism is found. © 2017, Springer Science+Business Media, LLC.

An efficient technique based on one dimensional beam finite element analysis for vibration of thin-walled laminated composite beams having open and closed sections is proposed in this paper. The developed technique is quite generic which can accommodate any stacking sequence of individual walls and considers all possible couplings between different modes of deformation. The formulation has accommodated the effect of transverse shear deformation of walls as well as out of plane warping of the beam section where the warping can be restrained or released. The inclusion of shear deformation has imposed a problem in the finite element formulation of the beam which is solved successfully utilising a concept developed by one of the authors. A number of numerical examples of open section (I and C sections) beams and closed section box beams are solved by the proposed technique and the results predicted by the proposed model are compared with those obtained from literature as well as detailed finite element analysis using a commercial code. The results show a very good performance of the proposed modelling technique.

The paper presents the construction of vibration -assisted spring-loaded batcher, its principle of operation is described, the spring-loaded batcher transverse vibration forms and the dependence of the vibration frequency and the amplitude on the dosed liquid are introduced. Mathematical modelling and the experimental results are presented in the paper. DOI: http://dx.doi.org/10.5755/j01.mech.21.4.9977

The process of laser generation of pulses of symmetrical and antisymmetrical Lamb waves in a ferromagnetic plate due to the thermoelastic effect was experimentally studied. The temperature dependences of the shape, amplitude, duration, and vibration frequency of acoustic pulses and the velocities of their propagation in the plate were investigated. © 2011 Pleiades Publishing, Ltd.

OBJECTIVES: To investigate changes in digital circulation during and after exposure to hand transmitted vibration. By studying two frequencies and two magnitudes of vibration, to investigate the extent to which haemodynamic changes depend on the vibration frequency, the vibration acceleration, and the vibration velocity. METHODS: Finger skin temperature (FST), finger blood flow (FBF), and finger systolic pressure were measured in the fingers of both hands in eight healthy men. Indices of digital vasomotor tone-such as critical closing pressure and vascular resistance-were estimated by pressure-flow curves obtained with different hand heights. With a static load of 10 N, the right hand was exposed for 30 minutes to each of the following root mean squared (rms) acceleration magnitudes and frequencies of vertical vibration: 22 m.s-2 at 31.5 Hz, 22 m.s-2 at 125 Hz, and 87 m.s-2 at 125 Hz. A control condition consisted of exposure to the static load only. The measures of digital circulation and vasomotor tone were taken before exposure to the vibration and the static load, and at 0, 20, 40, and 60 minutes after the end of each exposure. RESULTS: Exposure to static load caused no significant changes in FST, FBF, or indices of vasomotor tone in either the vibrated right middle finger or the non-vibrated left middle finger. In both fingers, exposure to vibration of 125 Hz and 22 m.s-2 produced a greater reduction in FBF and a greater increase in vasomotor tone than did vibration of 31.5 Hz and 22 m.s-2. In the vibrated right finger, exposure to vibration of 125 Hz and 87 m.s-2 provoked an immediate vasodilation which was followed by vasoconstriction during recovery. The non-vibrated left finger showed a significant increase in vasomotor tone throughout the 60 minute period after the end of vibration exposure. CONCLUSIONS: The digital circulatory response to acute vibration depends upon the magnitude and frequency of the vibration stimulus. Vasomotor mechanisms, mediated both centrally and locally, are involved in the reaction of digital vessels to acute vibration. The pattern of the haemodynamic changes in the fingers exposed to the vibration frequencies used in this study do not seem to support the frequency weighting assumed in the current international standard ISO 5349.

The purposes of this study are to develop a simulator generating a ski board vibration in actual skiing and to perform the basic construction for clarifying the ski sliding mechanism, which still has not been clarified completely. In the simulator developed in this study, the surface on the bottom of the ski was assumed as to be a snowy slope and a mass of snow (snow pack) assuming a skier had slid on this ski bottom surface. A ball vibrator connected to a large- sized compressor was installed onto the ski panel in order to vibrate a ski board. The compressed air from the compressor rotated a steel ball in the vibrator at high speed, causing vibration on the ski. A dynamic friction force ( F ) was detected by the digital force gauge when the snow pack was sliding from the top of the ski to the tail on the surface formed by the bottom of the ski. A coefficient of kinetic friction ( μk ) was calculated using this dynamic friction force. Furthermore, the velocity and acceleration of the snow pack were measured by two high speeded cameras. The experiment for confirming the validity of this simulator was carried out in the temperature conditions of -5 °C. The velocity and acceleration of the snow pack with vibration were higher than without vibration. On the other hand, the coefficient of kinetic friction ( μk ) with vibration was lower than without vibration. From these results, the simulator is suitable for studying the role of vibration in ski sliding and for clarifying the ski sliding mechanism.

Using modified Nyquist contours, the dominant poles of the closed loop delay-differential equation for machining systems such as milling are identified. Contours with constant damping ratio of the dominant poles are constructed using this method. These contours are similar in shape to the stability lobes, but move upwards and to the right as the instability parameter increases. Additionally, it is possible to study the movement of the dominant poles to the right-hand side of the complex plane as the system becomes unstable by increasing the depth of cut at a constant spindle speed. The movement of the dominant pole is shown to be towards the right (unstable) and upward (higher vibration frequency) of the complex plane. In some cases, there would be a jump of vibration frequency due to the change of the lobe number. It is also shown that the damping ratio of the structure strongly affects both the vibration frequency and the damping ratio of the dominant poles in the closed loop system. Finally, in two milling experiments with two different spindle speeds and continuously increasing depth of cuts, vibration frequencies are measured and compared to the theoretical predictions. The measurements agree with the theoretical predictions, particularly in the unstable cutting conditions. CC BY-NC-ND 3.0The research presented in this paper has been supported by InnKa project, an ERDF project. The contribution is greatly appreciated. InnKa