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In Korea, a precast floating track with anti-vibration isolators was recently developed to reduce the vibration and noise in urban railway stations, without disrupting train operations. This precast floating slab track is a newly developed structure and differs from existing conventional slab tracks. In this study, a Finite Element Method program (MIDAS CIVIL 2019) was used to analyze the load-carrying ability of structures under the train axle loads. After finishing the design, to understand more precisely about load transfer efficiency of this type of track, an assembly test (two load cases) was conducted with three precast panels (with rail 60 K mounted on) and compared with Finite Element Analysis results. The final results satisfied the test standards in Korea, which confirms that the precast floating track has an acceptable safety factor and structural behavior.

Several studies on the perception of impact sounds question the correlation of standardized approaches with perceived annoyance, while more recent studies have come to inconsistent conclusions. All these studies neglected the aspect of whole-body vibrations, which are known to be relevant for the perception of low-frequency sound and can be perceived especially in lightweight constructions. Basically, the contribution of vibrations to impact sound annoyance is still unknown and could be the reason for the contradictory results. To investigate this aspect, we measured vibrations on different types of floors under laboratory conditions and in situ. For this purpose, a vibration-sensing device was developed to record vibrations more cost-effectively and independently of commercial recording instruments. The vibrations of predefined impact sequences were recorded together with the sound field using a higher-order ambisonics microphone. In addition, a vibration exposure device was developed to expose the test objects to the exact vibrations that occur in the built environment. The vibration exposure device is integrated into the ambisonics reproduction system, which consists of a large number of loudspeakers in a spherical configuration. The article presents the development and performance achieved using the vibration-sensing unit and the vibration exposure device. The study is relevant for conducting future impact sound listening tests under laboratory conditions, which can be extended to include the reproduction of vibrations.

Vibration-assisted machining (VAM) is a process in which high-frequency small amplitude vibration is applied on tool or workpiece to improve cutting performance, especially for hard and brittle materials. It has been applied to several machining processes including drilling, turning, grinding, and milling. This paper offers a review for the vibration devices used in VAM process. The history and current status of the vibration devices are presented including the design theory and principles. The developed vibration devices are categorised in two groups, namely resonant and non-resonant modes. Advantages and limitations of these devices are summarized and discussed, including their development trend. In addition, the benefits and applications of vibration-assisted machining are also introduced.

The increasing demand for accuracy and miniaturization has greatly highlighted the significance of micro-drilling, and it has become a prominent micromachining technique. The capacity to accurately drill holes in various materials has brought about significant improvements across several industries, facilitating them to achieve new levels of productivity and effectiveness, such as in aerospace, automobiles, medical, and microelectronics. However, due to the growing demands of these industries, conventional micro-drilling (CMD) is no longer sufficient to achieve precision accuracy. Therefore, to meet the requirements, researchers have proposed ultrasonic vibration-assisted micro-drilling (UVAMD), a versatile, cost-effective, and efficient technique based on the CMD. It is a novel technique to achieve enhanced machining accuracy by applying high-frequency, low-amplitude vibrations directed toward the tool or workpiece in the feed direction. The use of vibrations enhances chip breaking, hence reducing burr formation, thrust forces, and rubbing between the tool and chip, resulting in superior surface finish quality of the micro-hole, especially for difficult-to-cut materials. This review article evaluates cutting tools and workpiece materials, along with the effects of UVAMD on chip morphology, burr formation, tool wear, cutting forces, and surface integrity. Additionally, it summarizes the ultrasonic vibration devices used for micro-drilling and the sustainability aspects of ultrasonic vibration machining.

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.

In mechanical engineering, the building industry, and many other branches of industry, vibration machines are widely used, in which circular and directed oscillations predominate in the form of movement of the working equipment. This article examines methods for generating asymmetric oscillations, which are estimated by a numerical parameter, namely by the coefficient of asymmetry of the magnitude of the driving force when changing the direction of action in a directed motion within each period of oscillations. It is shown that for generating asymmetric mechanical vibrations, vibration devices are used, consisting of vibrators of directed vibrations, called stages. These stages form the total asymmetric driving force. The behavior of the total driving force of asymmetric vibrations and the working equipment of the vibration machine are described by analytical equations, which represent certain laws of motion of the mechanical system. This article presents a numerical analysis of methods for obtaining laws of motion for a two-stage, three-stage, and four-stage vibration device with asymmetric oscillations. An analysis of the methodology for obtaining a generalized law of motion for a vibration device with asymmetric oscillations is performed based on the application of polyharmonic oscillation synthesis methods. It is shown that the method of forming the total driving force of a vibration device based on the coefficients of the terms of the Fourier series has limited capabilities. This article develops, substantiates, and presents a generalized method for calculating and designing a vibration device with asymmetric oscillations by the value of the total driving force and a given value of the asymmetry coefficient in a wide range of rational designs of vibration machines. The proposed method is accompanied by a numerical example for a vibration device with an asymmetry coefficient of the total driving force equal to 10.

We consider vibration devices that consist of softly vibration-isolated rigid bodies subjected to vibrations transmitted by means of inertial vibration exciters (unbalanced rotors) driven into rotation by electric motors. Typically, when designing such devices, it is assumed that the rotors rotate uniformly with a certain circular frequency and the body performs small harmonic oscillations with the same frequency. The present work, using a second-order approximation of their nonlinear coupled differential equations, shows that the rotor and the oscillating body keep exchanging energy. At the same time, the angular velocity of the rotor oscillates with the working frequency as well as with its multiple frequencies during each revolution. As a result, the acceleration of the oscillating body also acquires harmonics with multiple frequencies. This may cause both unwanted and beneficial resonance phenomena. We obtain formulae describing the magnitudes of these ripples. We show that the magnitude of oscillations of the angular frequency can also be estimated using energy considerations. Such estimates are provided for the three most common schemes of dynamic devices. Available experimental data confirm the main conclusions of the theory. We discuss both the harmful effects of these phenomena as well as their possible applications. The latter include design of bi-harmonic vibration exciters and exciters based on vibrational resonance. This article is part of the theme issue ‘Vibrational and stochastic resonance in driven nonlinear systems (part 2)’.

The primary goal of this study is to develop a wearable system for providing CNC machine operators with visual and tactile perception of triaxial cutting forces, thereby assisting operators in industrial environments to enhance work efficiency and prevent mechanical failures. To achieve this goal, we successfully integrated a virtual machining tool simulator with the remote-control wearable system (RCWS). Using the ‘King Path’ milling parameters, we employed the simulation software developed by the AIM-HI team to calculate static and dynamic cutting forces, converting this data into vibrational commands for the RCWS to generate corresponding tactile feedback. Furthermore, we conducted extensive experiments, testing various data conversion methods, including three sampling techniques and two data compression strategies, aiming to provide accurate tactile feedback related to cutting forces under different operating conditions.

Bulk feeders that can automatically feed materials are one of the most commonly used vibration devices in the electronics industry. This study uses voice coil motors to design and implement a dual-axis bulk feeder and a quad-axis bulk feeder, allowing them to handle many kinds of materials. The implemented feeders can improve some of the problems in traditional bulk feeders, such as only one direction of movement, can only handle one kind of material, the contact time between the material and the platform is too long, and the feeder is not suitable to process materials with particular shapes. Two or four voice coil motors are placed under the platform of the implemented feeder. The vibration of the platform is controlled by the up-and-down movements of the voice coil motors, so that the bulk materials on the platform can be moved to the desired direction according to the feeding requirements. This study proposes a control method to control voice coil motors. For example, using different combinations of up-and-down movements of these four voice coil motors, the quad-axis voice coil feeder can move the material in eight horizontal directions, such as up, down, right, left, up right, up left, down right, and down left, as well as vertically flip. Since the frequency and amplitude of each vibration of the voice coil motor can be easily and instantly adjusted through the program, the implemented feeder can handle other types of materials without modifying the hardware of the device. Finally, some experimental results illustrate that the implemented dual-axis and quad-axis voice coil feeders can indeed effectively handle various bulk materials.

The aim of this study was to investigate the effects of Equistasi®, a wearable device, on the relationship between muscular activity and postural control changes in a sample of 25 Parkinson’s disease (PD) subjects. Gait analysis was carried out through a six-cameras stereophotogrammetric system synchronized with two force plates, an eight-channel surface electromyographic system, recording the activity of four muscles bilaterally: Rectus femoris, tibialis anterior (TA), biceps femoris, and gastrocnemius lateralis (GL). The peak of the envelope (PoE) and its occurrence within the gait cycle (position of the peak of the envelope, PPoE) were calculated. Frequency-domain posturographic parameters were extracted while standing still on a force plate in eyes open and closed conditions for 60 s. After the treatment with Equistasi®, the mid-low (0.5–0.75) Hz and mid-high (0.75–1 Hz) components associated with the vestibular and somatosensory systems, PoE and PPoE, displayed a shift toward the values registered on the controls. Furthermore, a correlation was found between changes in proprioception (power spectrum frequencies during the Romberg Test) and the activity of GL, BF (PoE), and TA (PPoE). Results of this study could provide a quantitative estimation of the effects of a neurorehabilitation device on the peripheral and central nervous system in PD.