Vibration Cycle Research Articles

Features of the calculation for the fatigue of tower structure

This article describes the effect of the phenomenon of vortex shedding under the action of frontal wind on tower structures of solid crosssection.The phenomenon of vortex shedding occurs at wind speeds higher than certain critical ones, which on the Beaufort scale correspond to weak and moderate winds with a very large number of cycles, which requires the calculation of structures forendurance. An additional feature of this aspect is that the phenomenon of vortex shedding is quite unknown in broad engineering practice in Ukraine and for the first time a reference to the need to calculate structures for vortex excitation appeared with the introduction of Amendment 2 to DBN V.1.2-2:2006 "Loads and influences. Design standards" only in 2020. This article provides an analysis of existing calculation methods and the state of the provisions of national standards for thecalculation of tower structures for complex wind effects. In particular, the problems of calculating structures for dynamic action when calculating for frontal wind are indicated. The critical speeds for real tower structures and the approximate number of vibration cycles per year occurring during normal operation were also estimated. It was found that thenumber of cyclic self-oscillations from vortex shedding with a stress asymmetry coefficient ρ=-1 is from 2 to 15 million per year, which indicates the need to limit the stresses in structures and their details to the values of the endurance limit. Thearticle provides calculations of the values of the endurance limits for different groups of structures, analyzes the feasibility of using high-strength steel grades. An analysis of the reduction in the number of cycles when stresses exceed the endurance limit is also performed and it is proven that insignificant excesses of stresses within 3..5% can significantly reduce the endurance of structures by several times.This conclusion is especially relevant when calculating lattice-type space-frame structures that have an external enclosing shell that creates a wind effect in the structure similar to a solid-wall structure. Such features are relevant primarily for largescale monumental structures.

Prevention of the Fracture Problem Occurring in Automotive Alternator Heatsink Blocks Using Artificial Intelligence

In this study, prevention of fracture in vibration fatigue testing of automotive alternator heatsink blocks was investigated using an artificial neural network. Automotive components such as alternator heatsink blocks are subjected to high cyclic vibration fatigue loads throughout their lifespan, which can lead to the formation and propagation of fatigue cracks and ultimately component failure. The basic parameters affecting the resonant frequency of the heatsink blocks, including geometry and loading conditions, are determined. Data-driven decision making provides advanced predictive insights to analyze data for prediction and decisions using artificial intelligence approaches. An efficient artificial neural network model was defined to predict the resonance frequency in the vibration fatigue test. While the artificial neural network was trained to establish a functional relationship between the parameters and the resonance frequency, regression analysis was used to develop a predictive model to detect the resonance frequency of the heatsinks. The proposed approach aims to provide a comprehensive framework for preventing fracture problems in vibration fatigue tests of automotive alternator heatsinks and ultimately contribute to the reliable design and performance of these critical components. While the artificial neural network approach achieved high classification accuracy in predicting the new natural frequency, the regression model was also able to make accurate predictions. The results of this study showed that the time spent on design and simulation can be significantly reduced in preventing breakage problems that may occur before dynamic tests such as vibration tests of alternator components.

The application of ICPA optimization algorithm in multi-objective optimization structural design of prefabricated buildings

With the prefabricated buildings developing, traditional architectural design methods can no longer meet the requirements of efficient, green, and sustainable development. In view of this, based on the analysis of the framework structure of the cyclical parthenogenesis algorithm, the study introduced chaotic optimization algorithm for improvement. And the improved new algorithm was applied to multi-objective problems in the optimization design of prefabricated building structures. Finally, a novel structural design optimization model was proposed. These experiments confirmed that the improved algorithm had the least 160 iterations and 17 optimal solutions, which was an increase of 15 compared to traditional aphid algorithms. Two function solutions of this new structural design optimization model were both between –0:5 and 0.5, with relatively smaller values. In addition, this model could effectively optimize and transform physical buildings, increasing their structural stability by 2.43%, increasing their structural quality coefficient by 4.49%, reducing vibration cycles by 0.06%, and reducing inter story displacement angles by 0.04%. In summary, the improved cyclical parthenogenesis algorithm has good performance in solving multi-objective problems in prefabricated structures, and can quickly and accurately find the global optimal solution. This study aims to provide guidance for the prefabricated building structure design.

Development of a transverse-feeding vibration chiseling process for ultrafast and flexible texturing of metallic micropillars

Micropillar structures exhibit significant potential for various applications, including enhanced heat transfer to anti-icing, corrosion resistance, oil-water separation, and droplet manipulation. There is still a lack of high-efficiency and high-flexibility methods for the texturing of micropillars on metallic surfaces. Elliptical vibration chiseling has emerged as a novel process for fabricating high-aspect-ratio microstructures on metals. Nevertheless, the achievable structural shapes are primarily limited to microribs. This study proposes a transverse-feeding vibration chiseling (TFVC) process for the ultrafast and flexible fabrication of micropillars. In TFVC, an inclined 1D vibration trajectory is in the cutting plane, and a triangular-shaped tool moves perpendicularly to the cutting plane, which differs from conventional vibration cutting. As a result, a chip is generated but left on the surface in each vibration cycle, forming a micropillar structure. Due to the shear deformation in the chip, the grain of the micropillar structure material can be modified to present different contact properties from the substrate material. A finite element simulation is performed to explore the underlying mechanics and predict the surface generation of micropillar structures. Then, surface experiments are conducted on aluminum to verify the efficacy of the TFVC and explore its deterministic process parameters. The experimental results show a successful fabrication of micropillars by the TFVC. Finally, fish-scale-type microstructures and hierarchical grooves have been fabricated to demonstrate process flexibility. Furthermore, lotus leaf-inspired superhydrophobic surfaces and structurally colored surfaces with self-cleaning functions have been developed to illustrate the application potential of the TFVC.

City bus seat vibration analysis using 6-axis accelerometer and gyroscope sensors

This paper analyses different modes and cycles of seat vibration in city buses by analysing acceleration peak magnitudes and their trends and fluctuations in the time domain. The purpose is to find peak vibration modes that exist in the driving patterns of city buses. Analysing peaks in a time series is essential for many applications specifically in vibration analysis because they represent significant events. Using a 6-axis inertial measurement unit device which has accelerometer and gyroscope sensors data were collected from a number of city buses operating. By applying algorithmic filters the g-force peaks present in different acceleration modes were analysed. The particularity of city bus seat vibration and g-force acceleration levels due to effective acceleration in 3-axes are presented and discussed, namely: longitudinal (forward motion), lateral (side-to-side) and vertical (bounce mode) accelerations. It was found that the bus seat root mean square acceleration magnitude of approximately 0.33 g occurred from the major acceleration cycles during bus running. In longitudinal, lateral and vertical directions, 20% of peak acceleration cycles were above 0.20 g, 0.18 g and 0.27 g respectively. Jerk may be a better indicator of passenger discomfort. The results from this study can provide future reference to research directions into understanding city bus seat vibration levels in longitudinal, lateral and vertical directions and also initiatives to mitigate excess bus seat vibration for the riders.

Advanced ANN regularization-based algorithm for prediction of the fundamental period of masonry infilled RC frames

The fundamental period (TFP) of vibration is the time required for a structure to complete one full cycle of vibration, and it is one of the main features of the structural system. It highly influences the behavor of structures under earthquake excitation. Therefore, its determination is of highest importance for the seismic design of buildings. This is a complex task in a case of masonry infilled RC frames, due to high stiffness of infill walls and their interaction with the surrounding frame. In this study, using Artificial Neural Network (ANN) algorithms, the fundamental (natural) period of vibration of fully or partially masonry infilled Reinforced Concrete (RC) frame structures was evaluated. Accurate prediction of TFP has a key role in ensuring the safety and resilience of structures, which is particularly expressed in seismic-prone regions. The collected database from open literature contains 4026 samples which cover a wide range of RC frames. For practical reasons, the database is divided in the preprocessing phase into two parts that contain either bare frames or fully/partially infilled frames. The authors compared first and second-order ANN paradigms, and conducted feature importance analysis. The proposed models were validated and verified by comparison with the experimental data, seismic design codes, and derived equations by other researchers. In addition to the superiority that the BRA model has shown in comparison with other solutions, it also enables simpler approach for the calculation of TFP, unlike the proposals of other authors. Based on the results from best ANN model, multi-objective optimization genetic algorithm was employed for additional optimization of TFP which include investigation of the most optimal solutions between two conflicting objective functions.

Experimental study on compaction characteristics of coarse-grained soils with typical particle shapes affected by vibration frequencies

Coarse-grained soils, common fillers in subgrades, bear vibration loads in the construction stage, the compaction effects of which are affected by internal and external factors such as particle shapes and vibration frequencies. To enhance the understanding of compaction performance, this study investigated the vibration-induced deformation and energy dissipation of coarse-grained soils with two typical-shaped particles (pebbles and rubbles) through vibration compaction tests with different frequencies. Results show that both resilience modulus and damping ratio increase with increasing frequency, and the resilience modulus of rubbles is more stable compared with pebbles. Energy dissipation decreases with increasing vibration cycles at low frequencies, yet it increases with increasing vibration cycles at high frequencies. The dry density increment of rubbles is greater than that of pebbles, which is closely related to energy dissipation. Furthermore, the relationships between energy dissipation and dry density increment affected by particle shapes were discussed by discrete element simulations.

Flow-induced vibrations of an equilateral triangular prism at subcritical Reynolds number

It has been well known that the shear layers behind a prism at subcritical Reynolds number (Re) remain persistently stable. However, potential response of an elastically mounted non-circular prism at subcritical Re is still open. In this study, we numerically investigate the flow-induced vibrations of an equilateral triangular prism at subcritical laminar flow using the immersed boundary method. The prism is allowed to vibrate only in the transverse direction. It is found that the prism vibration could be excited and sustained at subcritical Re due to the instability triggered by the prism's movability. Within angles of attack α = 0°–60°, the triangular prism experiences three responses: i.e., vortex-induced vibration (VIV) at α = 0°–30°, large-amplitude vibration at α = 37.5°–46.5°, and galloping at α = 47.5°–60°. The characteristics of vibration amplitude, frequency, and dependence of fluid forces on reduced velocity and α are investigated. Eight different wake modes exist behind the prism, i.e., one stable mode, two shear layer modes, and five vortex shedding modes. In the VIV regime, the 2S mode (2 single vortices per vibration cycle) is the only vortex shedding mode, while the vortex shedding mode with more than two vortices is unique in the other two regimes. In the end, we discuss (i) the influences of Re and mass ratio and (ii) prediction of the galloping instability using quasi-steady analysis. It is found that three different response regimes are noticed, although their characteristics are strongly affected by the two factors. Quasi-steady approach could provide a reasonable prediction of the emergence of galloping instability for non-circular prism.

Impact of early-age vibration on the permeability and microstructure of mature-age concrete

Dynamic excitation in early-age significantly impacts the performances of mature concrete in underground structures, such as tunnels beneath railways supported by cast-in-place concrete. This study explores the impact of early dynamic excitation on properties of mature concrete. Vibration tests at a fundamental frequency of 114 Hz, with peak acceleration levels ranging from 0.1 g to 0.4 g, were conducted using shaking table. Specimens underwent 33 seconds of dynamic excitation every 15 minutes over the initial 48 hours, excluding a night break from 0 to 6am, totaling 114 vibration cycles. Various lab tests were employed to assess the properties and microstructure of mature concrete post-vibration, including water penetration resistance, capillary water absorption, Coulomb electric flux, scanning electron microscopy (SEM), mercury intrusion porosimetry (MIP) and Nitrogen adsorption-desorption measurement (NAM). The results proves that vibration causes water secretion and air bubbles discharge before the initial setting of concrete, thereby enhancing the hydration reaction. The relationship between vibration loads with varying peak accelerations and the cohesion resulting from hydration reaction influences the microstructural evolution of concrete, leading to the weakening and strengthening of permeability of mature concrete. Under the vibration spectrum and test conditions described in this paper, vibration loads with peak values less than 0.234 g decrease the total volume of large and middle pores (>20 nm) by up to 50 % and increase the total volume of small pores (<20 nm) by up to 200 %. Due to these changes in pore structure, the permeability coefficient (Sk), cumulative capillary water height (i) and Coulomb electric flux decrease by up to 47.84 %, 39.5 % and 31.6 %, respectively. However, when the amplitudes of vibration loads exceed 0.234 g, the total volume of large and medium pores (>20 nm) increases, and that of small pores (<20 nm) decreases, leading to a reduction of the impermeability of mature concrete. Additionally, the SEM analysis corroborates these microstructural variations.

Analysis of vocal fold movement and voice onset behavior in patients with laryngopharyngeal reflux based on high speed laryngeal high-speed videoendoscopy

Objective:Patients with Laryngopharyngeal Reflux（LPR） have chronic inflammation of the laryngeal mucosa leading to a high response state in the larynx, which may make the vocal fold movement too fast. This paper discusses the characteristics of vocal fold movement and voice onset by analyzing laryngeal high-speed videoendoscopy in patients with LPR. Methods:Forty patients with LPR were enrolled as LPR group. The diagnostic criteria of LPR included positive reflux symptom index（RSI） and reflux syndrome score（RFS） to identify suspected LPR, objective oropharyngeal DX pH monitoring was carried out, and positive Ryan index indicated reflux. According to age and sex matching, 40 healthy volunteers were selected as the normal group. Laryngeal high-speed videoendoscopy, and the vocal fold motion and vibration parameters, including vocal fold adduction time, vocal fold abduction time, vocal fold vibration onset mode（vocal onset time and mode） and the opening quotient of vocal fold vibration cycle. Statistical analysis was performed using SPSS 25.0. Results:The time of vocal fold adduction in LPR group（mean 225.81ms） was less than that in normal group（mean 277.01 ms）, and the difference was statistically significant（P<0.05）. There was no significant difference in adduction time between LPR group and normal group（P>0.05）. The vocal onset time in LPR group was significantly longer than that in normal group（P<0.05）. High speed video endoscope showed that there were 17 patients with hard onset in LPR group and 8 patients with hard onset in normal group, the difference was statistically significant（P<0.05）. There was no significant difference in the open quotient of vocal fold vibration between LPR group and normal group（P>0.05）. The vocal fold abduction time in LPR group（mean 372.92 ms） was less than that in normal group（mean 426.98ms）, but the difference was not statistically significant（P>0.05）. The time difference of bilateral abduction of vocal fold in LPR group was significantly higher than that in normal group（P<0.05）. Conclusion:The larynx of LPR patients is in a high response state, the vocal fold moves faster, and it is more likely to have a hard vocal onset. These may result in voice dysfunction.

Development and Experimental Study of an Experimental Setup for an Online Vibrating Tube Liquid Densitometer

Density is a crucial parameter for quantitatively describing the physical properties of liquids. It serves as an important indicator for scientific research, production process control, pipeline transportation, and other aspects. In oil pipeline transportation and raw material processing, the real-time online measurement of liquid density is of great significance. This paper analyzes the working principle of an online vibrating tube densitometer and derives the fitting equation for temperature, pressure, and density; it also conducts experiments with an online vibrating tube liquid densitometer and establishes a traceability chain for the experimental device. The experimental setup includes a desktop densitometer system, a multi-temperature field constant-temperature stirring system, a walk-in constant-temperature box, an automatic blowing system, and a frequency acquisition and calculation system. The uncertainty of the device’s evaluation is U = 0.08 kg/m3, k = 2. We built a set of pressure-density static test systems, statically testing the online vibrating tube’s liquid-density meter vibration frequency at different pressures; the whole set of systems can be used to assess the specific density, temperature, and pressure range of online vibrating tube liquid density meters in the experimental research to derive the standard temperature. Through the experimental research, we can accurately derive the fitting coefficients under the standard temperature, specific temperature, and pressure of online vibrating tube liquid densitometers, and calculate the fitting error of online vibrating tube liquid densitometers under different temperatures and pressures within the experimental range through fitting equations and coefficients, so as to realize the practical application of online vibrating tube liquid densitometers in engineering by utilizing straight-tube-type and curved-type online vibrating tube densitometers. A preliminary study was conducted on the effects of different densities, temperatures, and pressures on the vibrating tube system’s vibration cycle. The fit coefficient and error were calculated, and the experimental results were compared to the theoretical analysis to confirm the device’s conformity. The study verified the device’s scientific and reasonable design, and demonstrated that it is feasible to use the device for follow-up research. Using this device in subsequent experiments can verify the effects of viscosity, inlet, installation, and other factors on the online vibrating tube liquid densitometer’s metrological performance. Further experimental research on the pressure–frequency–density test system and the establishment of a wide range of temperatures and pressures within the pressure standard density test system are needed to achieve a wide range of temperatures and pressures under the standard density test.

Study on Dynamic Strength Characteristics of Sand Solidified by Enzyme-Induced Calcium Carbonate Precipitation (EICP).

Saturated sand foundations are susceptible to liquefaction under dynamic loads. This can result in roadbed subsidence, flotation of underground structures, and other engineering failures. Compared with the traditional foundation reinforcement technology, enzyme-induced calcium carbonate precipitation technology (EICP) is a green environmental protection reinforcement technology. The EICP technology can use enzymes to induce calcium carbonate to cement soil particles and fill soil pores, thus effectively improving soil strength and inhibiting sand liquefaction damage. The study takes EICP-solidified standard sand as the research object and, through the dynamic triaxial test, analyzes the influence of different confining pressure (σ3) cementation times (CT), cyclic stress ratio (CSR), dry density (ρd), and vibration frequency (f) on dynamic strength characteristics. Then, a modified dynamic strength model of EICP-solidified standard sand was established. The results show that, under the same confining pressure, the required vibration number for failure decreases with the increase in dynamic strength, and the dynamic strength increases with the rise in dry density. At the same number of cyclic vibrations, the greater the confining pressure and cementation times, the greater the dynamic strength. When the cementation times are constant, the dynamic strength of EICP-solidified sand decreases with the increase in the vibration number. When cementation times are 6, the dynamic strength of the specimens with CSR of 0.35 is 25.9% and 32.4% higher than those with CSR of 0.25 and 0.30, respectively. The predicted results show that the model can predict the measured values well, which fully verifies the applicability of the model. The research results can provide a reference for liquefaction prevention in sand foundations.

Development of a space-compatible packaging system for an integrated monolithic ultra-stable optical reference.

We report the development of a space-compatible packaging system for an integrated monolithic ultra-stable optical reference toward China's next-generation geodesy mission with low orbit satellite-to-satellite tracking. Building on our previous work, we optimized the mounting structure and thermal insulation mechanism using the finite element method. The comprehensive simulation results demonstrated the robustness of the entire packaging system with enough margins to withstand severe launch loads and maintain an ultra-high geometric cavity length stability. A long-term prediction of the vacuum maintenance around the cavity during in-orbit operation was conducted. An engineering prototype, within which an integrated monolithic optical reference has been mounted, was built based on our optimized design, and it has successfully passed typical aerospace environmental tests, including sinusoidal vibration (∼10g, 10-100Hz), random vibration (∼0.045g2/Hz, 10-2000Hz), and thermal cycling (0-45, 3 °C/min, lasting for 90h). The experimental thermal time constant of the prototype exceeded 9.5 × 104 s, enabling a temperature stability of 1.1 × 10-6K/Hz1/2 at 10 mHz on the optical cavity, with external active temperature control. The design is also suitable and useful for laboratory and terrestrial applications.

Thermoelastic damping properties in hemi-ellipsoidal shells with variable thickness

Thermoelastic damping (TED) is a fundamental dissipation mechanism that inevitably exists in shell resonators with high quality factors. Based on the thermal energy method, this paper demonstrates an effective method for the TED characterization of the hemi-ellipsoidal shells with variable thickness which manifest lower TED compared with the hemispherical shells. The equation of motion of the hemi-ellipsoidal shell under clamped-free boundary conditions is established by Hamilton's principle and the assumed mode method, and the natural frequencies and mode shape functions of the hemi-ellipsoidal shell with variable thickness are obtained by solving the eigenvalue problem. The temperature field is acquired by solving the heat conduction equation along the radial direction, and an analytical model for the TED of the hemi-ellipsoidal shell with variable thickness is presented by calculating the maximum elastic potential energy and the work lost per cycle of vibration due to irreversible heat conduction. Analysis on TED at the vibration patterns of meridional wave number m = 1 and the circumferential wave number n = 2 or 3 where the shell resonators typically operate is carried out. The analytically calculated TED results are compared with those of the finite element method (FEM) to verify the feasibility and correctness of the present method. The influences of the geometrical parameters on the TED characteristics of the hemi-ellipsoidal shells with variable thickness are analyzed in detail. A meaningful discovery is that compared with the hemispherical shell, the hemi-ellipsoidal shell with variable thickness has a smaller TED when its semiminor axis is shorter than the semimajor axis, which is particularly significant for optimizing the design of the shell resonators with high quality factors.

Identification of amplitude-dependent aerodynamic damping from free vibration data using iterative unscented kalman filter

This study presents an innovative approach employing an iterative Unscented Kalman Filter (IUKF) for the identification of amplitude-dependent nonlinear aerodynamic damping using wind tunnel free vibration data. The wind-structure interaction system is represented as a single-degree-of-freedom system, with the amplitude-dependent aerodynamic damping modeled as a polynomial function of structural displacement and velocity. The augmented state variables, encompassing structural vibration frequency and polynomial coefficients for aerodynamic damping, are concurrently estimated from free vibration data using the UKF technique. To enhance the robustness of the identification results against variations in initial conditions, the UKF is applied iteratively by assigning the estimated polynomial coefficients as new initial values for the state variables. Validation of the IUKF-based method is performed through a numerical example featuring a typical bridge deck sectional model, as well as experimental data from two spring-suspended sectional models experiencing vertical vortex-induced vibration (VIV) and torsional post-flutter limit cycle oscillation. The feasibility of identifying amplitude-dependent aerodynamic damping for amplitude range not covered by the displacement signal is examined.

Results of the cyclic triaxial testing on mechanically-biologically treated waste.

Accurate assessment of the dynamic strength characteristics of mechanically-biologically treated (MBT) waste is crucial for the construction and safe operation of landfill sites. Herein, samples of MBT waste from the Hangzhou Tianziling landfill were collected and subjected to consolidated undrained cyclic triaxial tests under four confinement levels and six cyclic stress ratios (CSRs). Under cyclic loading, the MBT waste exhibited a critical CSR. If the CSR exceeds the critical value, the MBT waste specimen rapidly undergoes deformation and failure. Dynamic strength of MBT waste decreases with an increase in the number of cyclic vibrations and increases with an increase in confining pressure. Considering the influence of cyclic vibrations and confining pressure, a formula for dynamic strength in terms of cyclic vibrations and confining pressure has been established. The dynamic shear strength parameter ranges for MBT waste were obtained under different seismic magnitudes. We compared the dynamic and static shear strength parameters of MBT waste and municipal solid waste. These study findings can serve as a reference for the dynamic stability analysis of MBT waste landfills.

Chip breakage in silk microfibre production using elliptical vibration turning

To overcome the precision limitation and environmental impact of current chemical-based production methods for manufacturing silk microfibres used for targeted drug delivery, this paper presents a high-precision, scalable, eco-friendly mechanical machining approach to produce such microfibres in the form of discontinuous chips obtained through elliptical vibration turning of silk fibroin film using a diamond tool. The length and waist width of fabricated microfibres can be precisely controlled. As each vibration cycle will produce one silk microfibre, complete and deterministic chip breakage becomes an essential and challenging task in this approach due to its unique two-phase structure. Thus, the hybrid FE-SPH numerical simulations and machining experiments were conducted to gain a pioneering and in-depth exploration of the chip-breaking mechanism in this process. It was found that applying a low depth ratio (ratio of the nominal depth of cut to the tool path vertical amplitude) and a high horizontal speed ratio (the nominal cutting speed versus the critical workpiece velocity) could effectively reduce the average tool velocity angle (the angle from the deepest cut to the tool exit point along the cutting direction). A smaller angle would enhance the diamond tool's shearing action and led to the reduction of hydrostatic pressure in the cutting zone and a consequent decrease in the ductility of silk fibroin due to its unique structure dominated by beta-sheet crystallites. The above adjustments collectively facilitated chip breakage. This paper, therefore, established a governing rule for the controlled and repeatable formation of microfibres based on the average tool velocity angle for the first time and revealed that the cutting chips would undergo complete and deterministic breakages once the angle approached below 22.6°. On this basis, the high-precision and scalable manufacturing of silk microfibres with precisely controllable length and waist width was ultimately achieved.

Transportation of Objects on an Inclined Plane Oscillating in the Longitudinal Direction Applying Dynamic Dry Friction Manipulations

A transportation system requires an asymmetry to achieve objects’ motion on an oscillating surface. Transportation methods based on vibrational techniques usually employ different types of asymmetries, such as temporal (time) asymmetry, kinematic asymmetry, wave asymmetry or power asymmetry. However, transporting an object on an inclined angle requires a relatively high net frictional force over each period of vibrational cycles due to the gravitational potential energy exerted on the object. This paper investigates the transportation of an object upward on an inclined plane that harmonically oscillates in its longitudinal direction. The novelty of this research is attributed to the upward motion of the object on the inclined plane, which is achieved by creating an additional asymmetry of the system through dry friction dynamic manipulations. For this reason, periodic dynamic dry friction manipulations have been employed to create the asymmetry of frictional conditions, resulting in a net frictional force that outweighs the gravitational force. A mathematical model has been developed using the Lagrange method, which describes the moving object’s motion. Moreover, the theoretical findings and results confirmed that the object’s velocity and direction can be controlled by dynamic dry friction manipulations. To demonstrate the technical feasibility of the proposed method, an experimental investigation was carried out where the results demonstrated that the control parameters significantly influence the characteristics of the directional motion of the moving object. This transportation method is beneficial for various modern industries engaged in transportation and manipulation tasks with objects spanning a broad range of sizes, including those operating at small scales for applications in lab-on-a-chip technology, micro-assembly lines, micro-feeder systems and other delicate component manipulation systems. The presented research advances the classical theories of vibrational transportation on inclined surfaces.

Theoretical and experimental investigation of ultrasonic cutting kinematics and its effect on chip formation and surface generation in high-frequency ultrasonic vibration-assisted diamond cutting

Ultrasonic vibration-assisted cutting (UVAC) is regarded as a feasible technology to machine difficult-to-cut materials. High-frequency ultrasonic vibration-assisted cutting (HFUVAC), with a working frequency of more than low and medium frequency (20–60 kHz), has been reported to improve material machinability and prolong tool life. This paper presents a comprehensive investigation of the ultrasonic cutting kinematics and the generated chip/surface formation process in HFUVAC of a 316l stainless steel workpiece. First, the ultrasonic cutting kinematics was analyzed and verified by comparing the experimental and theoretical surface texture under different nominal cutting speeds. Based on the ultrasonic cutting kinematics and the simulated strain/stress distributions, the chip and surface formation between conventional cutting (CC) and HFUVAC was analyzed. More importantly, the incremental cutting mode was defined when the cutting stroke, namely the effective cutting length in one vibration cycle was less than 800 nm. The results show that in the incremental cutting mode, defect-free surface was achieved due to suppressed large deformation and friction action. Finally, HFUVAC of the sinusoidal microstructure was performed under the incremental cutting mode, achieving optical requirements with nanometer-scale surface roughness and submicrometric form accuracy, which validates the technical feasibility in HFUVAC of micro-structured surfaces.

An abdominal vibration combined with walking exercise (AVCWE) program for older patients with constipation: Development and feasibility study.

Older patients with constipation are at higher risk for inadequate bowel preparation, but there are currently no targeted strategies. This study aims to develop an abdominal vibration combined with walking exercise (AVCWE) program and assess its feasibility among older patients with constipation. Phase I: Using the Delphi technique, eight experts across three professional fields were consulted to develop the AVCWE program. The experts evaluated and provided recommendations on demonstration videos and detailed descriptions of the preliminary protocol. Phase II: A single-arm feasibility study of the AVCWE program was conducted on 30 older patients with constipation undergoing colonoscopy at a tertiary hospital in China. A 10-point exercise program evaluation form and several open-ended questions were used to gather feedback from participants regarding the program. In both phases, content analysis was used to critically analyze and summarize qualitative suggestions for protocol modifications. Based on feedback from the expert panel, the AVCWE program developed in Phase I included two procedures during laxative ingestion: at least 5,500 steps of walking exercise and two cycles of moderate-intensity abdominal vibration (each cycle consisted of 10 min of vibration and 10 min of rest). The feasibility study in Phase II showed high positive patient feedback scores for the program, ranging from 9.07 ± 0.74 to 9.73 ± 0.52. The AVCWE program was developed by eight multidisciplinary experts and was well accepted by 30 older patients with constipation. Study participants believed that this program was simple, safe, appropriate, and helpful for their bowel preparation. The findings of this study may provide valuable information for optimizing bowel preparation in older patients with constipation.