Search

The lining cavities in tunnels have strong concealment and pose significant risks, seriously affecting tunnel operational safety. Therefore, it is necessary to develop efficient and high-precision detection techniques for tunnel lining cavities. In this study, concrete slabs with different parameter cavities were selected as the research object, and experiments on remote detection using Laser Doppler Vibrometry were conducted. During the experiments, the vibration parameters of the concrete surface were measured for cavities of varying sizes and depths, filled with different materials, and under different detection distance conditions. The vibration differences between the defective and healthy parts were analyzed using the spatial spectral entropy algorithm. The results showed that for cavities with side lengths of 200mm, depths of 50mm, and filled with hollow wooden boxes, the maximum velocity amplitudes of the surface concrete were 10.68, 3.55, and 4.01 times higher than those of the healthy parts, respectively. Moreover, at the same frequency, larger cavity areas and shallower depths resulted in greater surface vibration amplitudes. The vibration amplitudes of the surface with hollow wooden box filling were higher than those with foam polystyrene board filling. With increasing detection distance, the overall surface vibration velocity of the cavities was higher at a distance of 3 m from the laser probe compared to 5 m, indicating the ability to quantitatively describe the apparent vibration characteristics of concrete cavities under different parameters. This study demonstrates the significant effectiveness of laser Doppler vibrometry in remote detection of lining cavities in tunnels. [ABSTRACT FROM AUTHOR]

In this paper, the thermomechanical buckling and vibration analysis are investigated for carbon nanotube‐reinforced composite sandwich doubly curved shells (CNCSDS) under the action of both thermal loads and in‐plane compressive loads. Based on the von‐Karman non‐linear kinematic relations, First Order Shear Theory, and Hamilton's principle, the vibration and stability equations for CNCSDS under thermomechanical loads are deduced. For obtaining the critical thermomechanical buckling load and vibration frequency, an exact method is adopted. Subsequently, the results are validated by comparing with the finding in published literature and simulation results. At last, the influence of system parameters on critical thermomechanical buckling load and vibration frequency is studied and displayed graphically. Meanwhile, some new results about thermomechanical buckling and vibration analysis of CNCSDS are proposed for the first time. Highlights: Thermomechanical buckling and vibration of carbon nanotube‐reinforced composite sandwich doubly curved shells was studied.Vibration and stability equations under thermomechanical loads was deduced.The change rules of thermomechanical buckling load and frequency were obtained. [ABSTRACT FROM AUTHOR]

With the advancement of industrial automation, vibrational energy generated by machinery during operation is often underutilized. Developing efficient devices for vibration energy harvesting is thus essential. Triboelectric nanogenerators (TENGs) based on spring and cantilever beam structures show considerable potential for industrial vibration energy harvesting; however, traditional designs often fail to fully harness vibrational energy due to their structural limitations. This study proposes a triboelectric nanogenerator (TENG) based on a crank-rocker mechanism and a spring cantilever structure (CR-SC TENG), which combines a crank-rocker mechanism with a spring cantilever structure, designed for both energy harvesting and self-powered sensing. The CR-SC TENG incorporates a spring cantilever beam, a crank-rocker mechanism, and lever amplification principles, enabling it to respond sensitively to low-frequency, small-amplitude vibrations. Utilizing the crank-rocker and lever effects, this device significantly amplifies micro-amplitudes, enhancing energy capture efficiency and making it well suited for low-amplitude, complex industrial environments. Experimental results demonstrate that this design effectively amplifies micro-vibrations and markedly improves energy conversion efficiency within a frequency range of 1–35 Hz and an amplitude range of 1–3 mm. As a sensor, the CR-SC TENG's dual-generation units produce output signals that precisely reflect vibration frequencies, making it suitable for the intelligent monitoring of industrial equipment. When placed on an air compressor operating at 25 Hz, the first-generation unit achieved an output voltage of 150 V and a current of 8 μA, while the second-generation unit produced an output voltage of 60 V and a current of 5 μA. These findings suggest that the CR-SC TENG, leveraging spring cantilever beams, crank-rocker mechanisms, and lever amplification, has significant potential for micro-amplitude energy harvesting and could play a key role in smart manufacturing, intelligent factories, and the Internet of Things. [ABSTRACT FROM AUTHOR]

This research aims to study the mechanical behavior of the materials most commonly used in crankshaft manufacturing by designing a four-piston crankshaft, analyzing the stresses and displacements resulting from the applied load, and determining vibration frequencies. Additionally, this study examines the thermal behavior of the crankshaft. For this purpose, a three-dimensional model of the crankshaft was designed using CATIA V5 R18 software, and finite element analysis was subsequently performed using ANSYS 2019 R1 software under static, dynamic, and thermal conditions with four different materials in various orientations. To verify the effectiveness of the proposed design, it was compared with a reference design in terms of stresses and displacements. This study also explores improvements in crankshaft geometry and shape. The results indicate that selecting the appropriate material for the working conditions and optimizing the geometry and shape enhance engine performance and reduce the crankshaft's weight by 20%. The findings were validated by comparing the designs, which support increased productivity and improved durability. [ABSTRACT FROM AUTHOR]

Purpose: This paper investigates the vibration compaction mechanism and evaluates the impact of vibration frequencies on the stability of coarse-grained soil, aiming to optimize the subgrade filling process. Design/methodology/approach: This study examines the vibratory compaction behavior of coarse-grained soils through indoor vibration tests and discrete element simulations. Focusing on angular gravel (breccias) of varying sizes, the simulations were calibrated using parameters such as Young's modulus, restitution and friction coefficients. The analysis highlights how particle shape influences compaction, revealing mesoscopic mechanisms that drive macroscopic compaction outcomes. Findings: This study investigates the influence of vibration frequency on the compaction behavior of coarse-grained soils using discrete element simulation. By analyzing particle contact and motion, the mesoscopic mechanisms driving compaction are explored. The study establishes a positive linear correlation between contact force anisotropy (Cv) and deformation, demonstrating that higher anisotropy leads to greater structural disruption. Additionally, the increase in sliding contact percentage (SCP) at higher frequencies indicates instability in the skeletal structure, driven by uneven contact force distribution. These findings reveal how frequency-induced stress concentration affects the stability and deformation of the soil skeleton. Originality/value: This research explores the effect of various vibration frequencies on the compaction behavior of coarse-grained soils, examining microscopic interactions to reveal their impact on soil stability and deformation. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Carbon nanotubes (CNTs) have attracted considerable attention as nanomechanical resonators because of their exceptional mechanical properties and nanoscale dimensions. In this study, a novel CNT-based probe is proposed as an efficient nanoforce sensing nanomaterial that detects external pressure. The CNT probe was designed to be fixed by clamping tunable outer CNTs. By using the mobile-supported outer CNT, the position of the partially clamped outer CNT can be controllably shifted, effectively tuning its resonant frequency. This study comprehensively investigates the modeling and vibration analysis of gigahertz frequencies with loaded CNTs used in sensing applications. The vibration frequency of a partially clamped CNT probe under axial loading was modeled using continuum mechanics, considering various parameters such as the clamping location, length, and boundary conditions. In addition, the interaction between external forces and CNT resonators was investigated to evaluate their sensitivity for force sensing. Our results provide valuable insights into the design and optimization of CNT-based nanomechanical resonators for high-performance force sensing applications. [ABSTRACT FROM AUTHOR]

In the current paper, hygro-thermo-magnetically induced vibrations of small-scale viscoelastic tubes containing flow with a spin motion under gravity and tangential loads are analyzed by including surface effects. The dynamic equations are derived in the framework of the modified nonlocal elasticity theory (NET) and Rayleigh beam model. The Galerkin method and Laplace transformation are implemented to solve model equations. Vibration frequencies, stability boundaries, and Campbell diagrams of the system are acquired. Impacts of influential parameters such as scale rotary inertia factor, scale parameter, viscoelastic materials, gravity and tangential loads, flow and spin velocities, geometrical properties, and environmental conditions on the stability of the structure are examined. Also, the obtained results are compared for the Rayleigh and Euler-Bernoulli (EB) beam models. The golden results of this work are that by fine-adjusting the scale parameter and magnetic intensity in the system, destructive effects of hygro-thermal loads can be dampened. Besides, the increment of the rotary inertia factor and nanotube thickness induces destabilizing effect on the system. [ABSTRACT FROM AUTHOR]

Copyright of Science & Technology of Food Industry is the property of Science & Technology of Food Industry Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Featured Application: Sowing Rapeseed. The direct sowing of rapeseed requires shallow tillage for stubble removal, which can cause significant vibrations that impact the seed metering device, thereby affecting the quality of seeding. This study focuses on a double-row hole-wheel-type seed metering device on the 2BYG-220 type combined rapeseed planter. Initially, vibrations experienced by the seed drill during field operations were measured and analyzed, revealing that the vibration frequencies during field operations predominantly ranged between 0 and 25 Hz. Consequently, an eccentric wheel–return-spring-type vibration seed metering test rig was designed, manufactured, and set up. By swapping out the eccentric wheel on the test rig, the amplitude was mainly concentrated within 3 mm. The test results indicate that amplitude had a minimal impact on the performance of the double-row hole-wheel-type rapeseed seed metering device, whereas vibration frequency had a more significant effect. When the vibration frequency was between 0 and 10 Hz, the seed metering device maintained a stable output between 7.6 and 8.2 g/min, with minimal impact from vibrations: the coefficient of variation for seeding uniformity ranged between 35.81% and 44.58%, indicating stability and good uniformity. However, when the vibration frequency ranged from 10 to 24 Hz, the output of the seed metering device decreased rapidly and exhibited a linear relationship with frequency changes, with a determination coefficient (R2) of 0.92376. The coefficient of variation for seeding uniformity increased rapidly and also showed a linear relationship with frequency changes, with a determination coefficient (R2) of 0.87973. Vibrations with frequencies greater than 10 Hz had a considerable impact on the performance of the seed metering device. [ABSTRACT FROM AUTHOR]

Cable force estimation of the suspenders is of tremendous significance for the safety and condition evaluation of arch bridges. The modern suspender cable structure widely used nowadays calls for an efficient and robust estimation method accounting for the cable bending stiffness, complex boundary conditions, intermediate dampers, and variable suspender segments. To estimate the tension force in arch bridge suspenders, this paper proposes an exact analytical method that can simultaneously consider the aforementioned factors for the first time. Based on a generalized suspender cable model including all these factors, the transcendental equation for cable force calculation was obtained from the determinant of a 4 × 4 matrix derived using the transfer matrix method. Due to the low dimensionality of the matrix, the transcendental equation size is largely reduced. This allows rapid cable force calculation without requiring complicated numerical iteration algorithms. A dimensionless parametric analysis was conducted to investigate the impact of various factors on the frequency parameter of the suspenders. Subsequently, the efficacy of the proposed method was verified, and an extensive estimation error analysis was performed using finite elements. Moreover, the method was applied to four real-world bridges with measured vibration frequency available. The results showed that the method can accurately estimate the tension force in suspenders with flexural rigidity, arbitrary boundary conditions, and any number of intermediate dampers and nonuniform segments. The proposed method can also be used for suspender cable force estimation of other cable-supported bridges, such as suspension bridges. [ABSTRACT FROM AUTHOR]

The modeling and self-excited vibration mechanism in the magnetic levitation-collision interface coupling system are investigated. The effects of the control and interface parameters on the system's stability are analyzed. The frequency range of self-excited vibrations is investigated from the energy point of view. The phenomenon of self-excited vibrations is elaborated with the phase trajectory. The corresponding control strategies are briefly analyzed with respect to the vibration mechanism. The results show that when the levitation objects collide with the mechanical interface, the system's vibration frequency becomes larger with the decrease in the collision gap; when the vibration frequency exceeds the critical frequency, the electromagnetic system continues to provide energy to the system, and the collision interface continuously dissipates energy so that the system enters the self-excited vibration state. [ABSTRACT FROM AUTHOR]

Using Tokuda's improved linear combination operator method and variational technique, the expression of the polaron effective mass in a parabolic quantum well is derived. Due to the spin-orbit interaction, the effective mass ratio of polaron splits into two branches. The dependence of the effective mass ratio on the vibration frequency, the spin-orbit coupling parameter, and the velocity is discussed by numerical calculation in the presence and absence of phonon. The effective mass ratio of polaron is an increasing function of vibration frequency. The absolute value of the spin splitting effective mass ratio increases with the increase in the spin-orbit coupling parameter and decreases with the increase in velocity. Due to the heavy hole characteristic of spin-orbit interaction, the spin splitting effective mass ratio is negative. The effective mass ratio is larger in the presence of a phonon than in the absence of a phonon, and the effective mass ratio splitting distance is independent of the phonon. [ABSTRACT FROM AUTHOR]

The article discusses the design and the optimization of converters for converting vibration energy into electrical energy by using the vortex interaction of flows. Given the global need to transition to renewable energy sources in response to climate change, this research focuses on improving the structural efficiency of vibrational energy converters. By using a laboratory setup with a regular structure of transducers, the effect of the ratio of the width of the contact area of the transducer to the width of the free end on the amplitude and frequency of oscillations has been studied. Based on the results of the research, the optimal width ratio that maximizes vibration energy output while ensuring material efficiency and structural strength has been determined. The findings show that a minimum contact zone width not only reduces material costs, but also increases vibration energy output, which is key to the efficiency of energy conversion processes. Mathematical calculations of the vibration movements of converters based on experimental data provide a reliable basis for predicting performance and guiding design improvements of future installations. This study contributes to the broader field of renewable energy technologies by offering a detailed analysis of the parameters affecting the efficiency of vibrational energy converters. [ABSTRACT FROM AUTHOR]

Mechanized agriculture is the foundation of large-scale agriculture. However, in current mechanized corn cultivation, the cleaning efficiency during the cleaning phase is poor due to design defects, which in turn reduces its yield. Therefore, this study proposed an optimization of the corn screening device based on high-precision aerodynamic models. 3D modeling was used to explore the parameter optimization of the corn cleaning devices from an aerodynamic point of view, and certain improvements were made to the fish scale sieve structure. The results indicated that the cleaning efficiency was related to airflow velocity, vibration frequency, and the opening of the fish scale sieve. The optimal wind speed was 16 m/s, and the separation efficiency currently was 94.27%. The optimal vibration frequency was 8 Hz, and the separation efficiency currently was 97.24%. The optimal opening of the fish scale sieve was 26 mm, at which point the screening efficiency reached 100%. The optimized fish scale sieve reduced blockage by 63.7% compared to the traditional fish scale sieve, and ultimately achieved an impurity content of 1.4% with an improvement of 81.3%. In summary, the optimization plan proposed by this research can effectively improve the cleaning efficiency of corn and promote agricultural production and efficiency. [ABSTRACT FROM AUTHOR]

The solidification characteristics of commercially pure aluminum with and without vibration were investigated using experiments and numerical simulation methods. The results showed that the vibration condition is beneficial to the filling flow. The changes of melt flow and temperature field were studied and compared with those obtained without a mechanical vibration field. The existence of the mechanical force causes the melt velocity to be accompanied by abrupt fluctuations at different positions of the melt. However, the ending time of vibration solidification is slightly longer than that without applying mechanical vibration field. The application of mechanical vibration significantly refines the grain size, thereby increasing tensile strength and elongation. With the increase in vibration frequency, the solidification structure of the alloy is refined and then coarsened. It is, therefore, found that the optimal mechanical vibration frequency is 30 Hz. The present study can provide guidance for engineering practice in the vibration field. [ABSTRACT FROM AUTHOR]

Graphene has excellent mechanical properties and vibration frequency is an important mechanical property. In this paper, the effects of doping elements and doping concentrations on the vibration characteristics of graphene nanoribbons were investigated by molecular dynamics simulation. The vibration characteristics are influenced by the doping element, depending on the bond structural difference in bond structure between doping atoms and carbon atoms. The vibration frequencies of Nitrogen (N)-doped and Nitrogen–Nitrogen (N–N)-doped graphene nanoribbons are slightly lower than those of pure graphene nanoribbons. However, the vibration frequencies of Sulfur (S)/Phosphorus (P)-doped and Sulfur–Sulfur (S–S)/Phosphorus–Phosphorus (P–P)-doped graphene nanoribbons are significantly lower than those of pure graphene nanoribbons. In addition, with the increase of S (P) doping concentration, the vibration frequency of monolayer graphene nanoribbons decreases gradually. [ABSTRACT FROM AUTHOR]

In this study, we sought to characterize the effect of water vibration frequency stress on crimson snapper (Lutjanus erythropterus) survival to determine an optimal transportation speed. To achieve this, we used a transport tank (25 cm × 17 cm × 16 cm) to simulate the transport process. After 8 h at five different vibration frequencies (D1 = 75 rpm, D2 = 105 rpm, D3 = 135 rpm, D4 = 165 rpm, and D5 = 195 rpm), the pH and dissolved oxygen (DO) levels in the tanks decreased; ammonia nitrogen levels (NH4-N) and temperature (T) increased with increasing density; and significant changes in oxidative stress biomarkers, digestive enzymes, and ATPase levels were observed in crimson snapper fry. The enzyme activity increased and reached the maximum value at 195 rpm. The experimental results suggested that during the actual transport, when using transport tanks, the length of the transport time was less than 8 h, and setting the vibration frequency for transportation at 135 rpm was more appropriate, that is, a speed of 50 km/h for transporting crimson snapper fry. [ABSTRACT FROM AUTHOR]

The optimal process parameters of ultrasonic-assisted processing were studied to further improve the molding quality and mechanical properties of Ni60/WC-TiO2+La2O3 composite coating. A single-factor experiment was used to explore the influences of ultrasonic vibration frequencies on Ni60/WC-TiO2+La2O3 composite coating. The microstructure, elemental composition, phase composition, hardness, and wear resistance of the coating were studied using scanning electron microscopy (SEM), an X-ray diffractometer (XRD), an energy spectrometer, a microhardness meter, a friction and wear tester, and other equipment. Ultrasonic vibrations significantly improved the problems of pores in the coating, and the porosity was reduced from 0.13 to 0.014%. When the vibration frequency was 32 kHz in the experiment, the aspect ratio of the coating was optimized from 2.06 to 2.48, the dilution rate increased from 5.60 to 5.79%, the hardness increased from 960.25 to 988.45 HZ1.0, and the friction coefficient was reduced from 0.34 to 0.27. The coating performance was significantly improved, and the research results provide a reference for preparing excellent Ni60/WC-TiC+La2O3 composite coating. [ABSTRACT FROM AUTHOR]

The marine and alluvial plains along the southeastern coast of China are widely distributed in sandy formations, including smaller sand lenses and interlayers. The interlayers of sand have a significant impact on the mechanical properties of soft clay. In this paper, a large number of undrained unidirectional and bidirectional cyclic loading tests for soft clay with sand interlayers were carried out by a dynamic triaxial test system. Test results show that, under unidirectional and bidirectional cyclic vibration, the area of the hysteresis loop decreases and the slope of the connecting line at both ends of the hysteresis loop increases with the increasing of frequency. For the same vibration frequency, the area of the bidirectional vibration hysteresis loop and the slope of the connecting line at both ends are smaller than that of the unidirectional cyclic vibration. Under the same dynamic stress ratio, cumulative axial deformation caused by unidirectional and bidirectional vibration increases with the increasing frequency. Under unidirectional vibration, dynamic elastic modulus decreases at first, and then increases with the increasing frequency. For the same frequency, dynamic elastic modulus of the sample increases with the increase in cycles. Due to the effect of radial cyclic stress, the curves of dynamic elastic modulus and damping ratio with frequency under bidirectional vibration are opposite to those under unidirectional vibration. [ABSTRACT FROM AUTHOR]

During the smelting process of the AOD furnace, the unbalanced reaction of material will lead to the occurrence of splashing. It will not only damage the smelting equipment but also seriously injure the personnel. In this study, first, the information of liquid level, audio information and vibration information are detected by multiple sensors respectively. Then the fused information is used to forecast the splashing. Finally, the multitasking fuzzy controller is used to suppress splashing. The results show that the method of forecasting and suppressing splashing can accurately forecast and achieve rapid suppression. Thus the efficiency of smelting can be improved. [ABSTRACT FROM AUTHOR]

The seismic vulnerability assessment of existing structures is a well-known challenging task, due to a combination of several aspects. The use of analytical or finite element (FE) numerical models can offer robust support in this analysis but necessitates the accurate calibration of geometrical and mechanical input, with related uncertainties. In this paper, attention is focused on the identification of dynamic parameters, based on modal numerical analysis, of a 50-year-old, reinforced concrete, elevated water tank (EWT) characterised by a reservoir with a truncated cone shape. The structure is located in a high seismic region of northern Italy and presently necessitates retrofit plans to preserve its functionality. Based on the limited available experimental evidence and technical drawings, major efforts are spent for the numerical prediction of fundamental vibration modes and frequencies of the structure, which represent a first key step for seismic analyses, under various water-filling levels. To this aim, four different FE numerical strategies able to include both structural features and possible fluid–structure interaction (FSI) effects are developed. By progressively increasing the computational cost (and expected the accuracy of the solutions), FE models based on added-mass (M0 model), spring-mass (M1-DM or M1-DS models), or acoustic (M2 model) strategies are taken into account and combined with increasing detailing in geometrical description of the structure. Results from parametric modal analyses are discussed for the case-study EWT, in terms of computational cost, possible numerical limitations, accuracy of predicted frequencies/modal shapes, sensitivity to water-filling levels and operational configurations, with the support of several pieces of experimental evidence and consolidated analytical formulations for fundamental frequency estimations. [ABSTRACT FROM AUTHOR]

In particular environments, such as the Gobi Desert, the problems encountered in a project are complex, resulting in reduced stability of the anchoring system and multiple forms of failure. This paper takes the factors influencing the stability of sand anchors under vibration loads as the research background. Theoretical analysis and indoor model tests were used to study the load-bearing performance of sand anchors under vibration loads; in addition, a comparative analysis of this performance along with failure forms of sand anchor systems, various sand soil moisture contents, and vibration parameters was performed. The results of the study showed that as the water content becomes higher, the cohesive force of the sand decreases and produces a higher displacement in the water content, with most of the anchor solids becoming prone to fatigue failure. When the water content and vibration frequency remain stable and the vibration amplitude increases, the anchor rod is disturbed after the ultimate pullout bearing capacity forms a decreasing trend, with a decline rate of approximately 40%. By keeping the water content and vibration amplitude stable and changing the vibration frequency, the ultimate pullout capacity of the anchor does not change significantly, and the frequency reaches a certain level when it attains a compacting effect on the surrounding soil and thus has less influence on the anchor. The anchor pullout resistance bearing is most sensitive to the change in sand moisture content, more sensitive to the vibration amplitude, and less sensitive to the vibration frequency, but its correlation is not significant. [ABSTRACT FROM AUTHOR]

Copyright of Guangdong Architecture Civil Engineering is the property of Guangdong Architecture Civil Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

To illustrate the vibration characteristics of a rotating pipe in flow, experiments were conducted for a pipe in flow, a rotating pipe in still water and a rotating pipe in flow. For the pipe in flow without rotation, the trajectory diagram is '8' shaped. For the rotating pipe in still water, a multiple frequency component was induced, and a 'positive direction whirl' was found. For the flow and rotation, at a flow velocity of 0.46 m/s, the vibration is dominated by the combination of flow and rotation. With an increase in rotating frequency, the trajectory of the rotating pipe varies from an '8' shape to a circular shape and the 'reverse direction whirl' is induced, which is different from 'positive direction' in still water. The vibration frequency ratio increases uniformly with flow velocity. At a flow velocity of 1.02 m/s, at which the frequency is close to the theoretical natural frequency, the vibration frequency ratio is f*≈1. Predominantly governed by vortex-induced vibration (VIV), the vibration behavior of a rotating pipe subjected to fluid flow conditions has been found to exhibit complete vanishing of whirl. The vibration characteristics of a rotating pipe in flow are studied by the experiments which is benefit for structural drilling design. [ABSTRACT FROM AUTHOR]

• A systematic experimental study to investigate the influence of vibration amplitude, frequency, and subsequent vibration-induced acceleration on oil recovery. • Image analysis-based methodology to quantify dislodgment effectiveness, representing a form of oil recovery, is developed. • Experimental observations demonstrate seismic vibrations' effect in dislodging an entrapped fluid. • The observed data serve as a reference tool for computational studies while implementing them in the reservoir simulations. The impact of seismic vibrational amplitude and frequency in dislodging an entrapped diesel globule in a pore model is experimentally studied. The effective change occurring inside a 3D printed pore model estimated from a systematic image analysis methodology is developed to represent the oil recovery. The pore model is subjected to sinusoidal vibrations with amplitudes ranging from 0.1 mm to 2 mm and frequencies ranging from 5 to 100 Hz. Dislodgment of entrapped diesel is observed for frequency values between 40 and 80 Hz with vibration amplitude above 0.5 mm. Even though increasing the vibration frequency increases the vibration-induced acceleration, the dislodgment of the entrapped fluid is not observed at higher frequencies. Smaller vibration amplitudes imparted by the shaker and a possible slip flow at the oscillating walls occurring at higher frequencies are reasoned for this observation. [ABSTRACT FROM AUTHOR]

Perilous rock instability on the soil slope brings a substantial threat to project operation and even people's lives. The buried depth of the perilous rock is a challenge to deal with and primarily determines its stability, and the indirect rapid identification of its buried depth is the key to its stability evaluation. The paper aims to find a new and quick method to measure the buried depth of perilous rock on the soil slope and to solve the hard-to-measure buried depth stability evaluation. When the damping ratio is less than one, and the deformation is linear elastic throughout the amplitude range, the potentially perilous rock vibration model may reduce to a multi-degree-of-freedom vibration one. By theoretical deduction, a quantitative relationship is established among the perilous rock mass, the basement response coefficient, the buried depth of the perilous rock, and the natural horizontal vibration frequency. In addition, the accuracy of this relationship is confirmed via numerous indoor experiments, showing that the horizontal vibration frequency of the perilous rock model in one dimension increases as the buried depth increases. Finally, based on the natural vibration frequency and guided by the limit balance model, a stability evaluation model of the perilous rock on the soil slope is constructed. Hence, the example shows that the method is feasible. The research findings are of vital significance for the stability evaluation of the perilous rock on the soil slope and give a novel approach and theoretical foundation for quick identification and monitoring. [ABSTRACT FROM AUTHOR]

• System identification of monumental neoclassical masonry buildings is presented. • Nonparametric and parametric system identification techniques are compared. • Dynamic identification of damaged and retrofitted structures is presented. This paper presents structural condition assessment of some critical neoclassical monuments in Nepal using nonparametric and parametric system identification techniques. Neoclassical buildings in Nepal house critical administrative units. Structural condition assessment of such buildings is therefore important for the safety of their occupants and interrupted function during and after major earthquakes. The historical and cultural values of such monuments necessitate regular structural assessment for maintenance, repair, and preservation. Dynamic characteristics such as natural vibration frequencies of structures provide valuable insights on their structural condition. While numerical models are commonly used to estimate eigen frequencies of structures, they are associated with large uncertainties in massive monuments with complex structural and geometrical configurations. Noninvasive dynamic identification techniques provide an alternative means in such structures. Ambient vibration records from six neoclassical monuments in the Kathmandu Valley, Nepal are used in this study to estimate vibration frequencies of the structures in different states. The structures were damaged during the 2015 Gorkha earthquake, and subsequently retrofitted. Changes in vibration frequencies before and after retrofitting provide useful insights on structural improvement through retrofitting. Input-output and output-only system identification techniques are tested to simplify the structural condition assessment approach. We conclude that the state space system identification can stably quantify dynamic properties so stiffness variation can be confidently extracted, which is the key application for noninvasive structural system identification. Also, using minimum number of sensors, we captured damage aggravation deploying the modal assurance criterion. The outcomes indicate that structural condition assessment of complex structures is possible using a limited number of sensors for circumstances such as damage aggravation to temporal variation (evolution/reduction) of dynamic characteristics. [ABSTRACT FROM AUTHOR]

Copyright of Fly Ash Comprehensive Utilization is the property of Hebei Fly Ash Comprehensive Utilization Magazine Co., Ltd. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The durability of the products such as personal protective clothes and facemasks are crucial for human health as these products prevent the spread of disease. This study aims to investigate the seam strength of ultrasonically welded spunbond nonwovens used for personal protective clothes, facemasks, diapers and determine the best welding parameters for optimum seams. For these purposes, polyester and polypropylene spunbond nonwoven fabrics with different areal weights were ultrasonically welded by changing process parameters such as vibration frequency (%-kHz) and welding pressure (bar). The welded samples were evaluated according to the standard test method for seam strength and experimental data obtained from tests were statistically assessed by generating models and regression equations. The best seam strength for polyester nonwovens with different areal weights was achieved with 80% vibration amplitude and 1 bar or 1.5 bar welding pressures. In contrast, ultrasonic welding applied with 0.5 bar welding pressure and 63% or 70% vibration amplitudes resulted in the highest seam strengths for polypropylene nonwovens. [ABSTRACT FROM AUTHOR]

To reveal the action mechanism of vibration frequency in alfalfa opening compression, a self-developed vibration compression test system was used to evaluate the variation of compression force during alfalfa open compression. A faster vibration frequency yielded a smaller compression force required for compressing alfalfa into blocks. Compared with free vibration compression, vibration compression was beneficial to release the internal stress of alfalfa block, reduce the forming pressure, and stabilize the high density. In the range of test vibration frequency, when the frequency was 15 Hz, the residual internal stress release ratio of alfalfa block was the highest, and the stable density of alfalfa block was the largest. Considering the pressure and alfalfa block density comprehensively, the optimized vibration frequency was approximately 15 Hz [ABSTRACT FROM AUTHOR]

Experimental findings regarding the influence of vibration frequency on the machining outcomes of vibration-assisted machining (VAM) have been inconsistent. This work aims to address this issue through both experimental and theoretical analyses. The results indicate that the circuit's frequency response is the primary source of these discrepancies. When the vibration frequency is less than half the cutoff frequency, the friction force reaches a minimum while the wear volume peaks. The solution of the heat conduction equation demonstrated that the acoustic softening effect drives the softening mechanism in nanoscale VAM. Molecular dynamics (MD) simulations further elucidate the damage mechanisms during the wear process, showing that high-frequency vibrations contribute to achieving high-precision machining. [ABSTRACT FROM AUTHOR]

• An FBG sensing system for detecting partial discharge faults in cable joints by monitoring vibration signals from partial discharges. • Using a narrowband light source and FBG reflected power demodulation reduces the fault detection system's cost while ensuring high-resolution detection. • The power compensation method addresses the influence of the front-end FBG on the back-end FBG in a series configuration. This study presents a multi-point sensing system for cable fault detection based on fiber Bragg grating (FBG). The system detects vibration signals caused by cable faults through changes in the reflected power of the FBGs. By integrating time division multiplexing (TDM) technology, the system achieves multi-point fault detection and distinguishes vibration signals from faults at different cable locations. To verify the system's feasibility, different fault scenarios were simulated. The results show that the system can detect the vibration signals caused by cable joint faults, successfully demodulate the corresponding frequency components, and reconstruct the strain applied to the FBGs. Additionally, to address the impact of front-end FBG on back-end FBG, a power compensation method was developed to improve detection accuracy. The proposed cable fault detection system facilitates online detection of cable joint faults but also reduces system equipment costs, offering a novel approach to cable fault detection. [ABSTRACT FROM AUTHOR]

This study investigates the dynamic responses and associated wake structures of three identical tandem square cylinders oscillating in the cross-flow direction at a Reynolds number, R e = 150. The reduced velocity is varied within the range U ∗ = 3 − 14 , with a mass ratio of m ∗ = 2 considered. Finite element simulations are conducted for four streamwise gap configurations: L x = 3 B , 5 B , 8 B and 10 B , where B represents the cylinder's side length. Using the r m s values of amplitude and lift coefficient obtained for the above-mentioned streamwise gaps, a data-driven artificial numerical model is created to predict the amplitudes and lift coefficients for L x = 4 B , 6 B , 7 B and 9 B. For smaller streamwise gaps ( L x ≤ 4 B), all three cylinders exhibit four distinct oscillation regimes. However, the larger gaps promote vortex interaction with the downstream cylinders, leading to the emergence of different vibration regions for each body. The upstream cylinder experiences higher amplitudes for L x = 3 B compared to the L x = 10 B case, resulting in an upper response branch for smaller gap spacings. In contrast, the larger gaps result in less intense interference effects on the upstream cylinder, causing periodic oscillations across the entire U ∗ regime considered. Nevertheless, the two downstream bodies undergo frequency modulation in their vibration responses for larger gaps. These observations align with the periodic shedding of the upstream cylinder and modulations in the Strouhal frequency of the downstream bodies observed in the static system for L x > 4 B. • Three tandem square cylinders exhibit four oscillation regions with the gap of 3B • Vibrations are influenced by the flow characteristics of stationary system for larger gaps • FE simulations and a data-driven ANN model predict higher amplitudes for smaller gaps [ABSTRACT FROM AUTHOR]

• Commercial PV modules are experimentally and numerically investigated in mechanical terms. • A non-destructive diagnostic strategy based on vibration frequency analysis is proposed. • The attention is given to encapsulants consisting of thin interlayers made of Ethylene-Vinyl Acetate (EVA) • The effect of ageing, ambient conditions, humidity on EVA films is emphasized. • Results show that the frequency analysis can capture the encapsulant deterioration and prevent major faults. In engineering applications, the frequency analysis represents a first and practical step to collect relevant parameters for structural and mechanical diagnostics. Any possible material / component degradation and deterioration can be prematurely detected by frequency modifications that exceed a certain alert value. In this paper, the attention is given to the dynamic mechanical analysis of commercial photovoltaic (PV) modules, in which the solar cells are typically encapsulated in thin viscoelastic interlayers made of Ethylene-Vinyl Acetate (EVA), which are primarily responsible for the load-bearing capacity of the sandwich PV system. As a major effect of ageing, ambient conditions, non-uniform / cyclic thermal gradients, humidity and even extreme mechanical / thermal loads, the rigidity of these films can largely modify and decrease, thus possibly affecting the mechanical capacity of the PV module, and even exposing the solar cells to fault. Knowledge of the effective bonding level is an important step for diagnostic purposes. In this regard, the present study is based on a preliminary non-destructive experimental analysis, and on an extensive parametric Finite Element (FE) numerical investigation of full-scale commercial PV modules of typical use in buildings. The attention is given – for PV module arrangements of technical interest – to the effect of EVA stiffness in terms of vibration modes and frequency sensitivity. As shown, especially compared to newly installed PV modules, any kind of stiffness decrease is associated to major frequency modifications for the composite system, and in the worst configuration, such a frequency scatter can decrease down to −40% the original condition. Such a marked stiffness decrease would be implicitly associated to a weak mechanical performance of the sandwich section, with major stress peaks and deflections in the PV system, even under ordinary loads. The presented results, in this sense, suggest that major consequences can be prevented and minimized by monitoring the vibration frequency of PV modules. [ABSTRACT FROM AUTHOR]

Alkali residue-based foamed concrete (A-FC), consisting of cement, alkali residue, blast furnace slag, and foam, has great potential for application in subgrade engineering. A series of dynamic triaxial tests were conducted, and the influences of confining pressure, vibration frequency, and curing age on the dynamic properties of A-FC was revealed. Test results indicated that the backbone curves of A-FC exhibit a hyperbolic shape, effectively captured by the H-D model. After 7 days of curing, A-FC possessed robust dynamic bearing capacity. As the dynamic strain increases, the dynamic elastic modulus of A-FC exhibits an initial rise followed by a gradual decline. Concurrently, the damping ratio demonstrates an initial decrease and subsequent gradual increase. Elevated confining pressure, prolonged curing age, and higher vibration frequency were found to contribute to a progressive increase in the dynamic elastic modulus of A-FC. Throughout the damping ratio growth stage, the increasing curing age and confining pressure led to the decrease of damping ratio, with minimal influence from vibration frequency. A calculation model for the maximum dynamic elastic modulus of A-FC was proposed, considering confining pressure, vibration frequency, and curing age. This research underscores the capacity of A-FC to withstand cyclic loading, thereby offering valuable support for its engineering applications. • Analyzed the microscopic structure and the mechanism behind strength formation of A-FC. • Investigated the variations observed in the backbone curve, dynamic elastic modulus, and damping ratio. • Developed a comprehensive model to determine the maximum dynamic elastic modulus. [ABSTRACT FROM AUTHOR]

In this study, the vibration frequency of steel rod-type short suspenders simulated by three types of prestressed steel rebars with aspect ratios of 14, 20.8, and 37.8 was detected accurately and remotely by using Laser Doppler Vibrometer (LDV); then the tension force state of short suspenders was evaluated through the quadratic regression relationships between vibration frequency and tension force. The results showed that the vibration frequency of steel rod-type short suspenders increases with the increase in tension force, and there is a good correlation between vibration frequency and prestress. Furthermore, when the prestress applied is the same, the vibration frequency of short suspenders decreases with the increase of their aspect ratios, indicating aspect ratio plays a decisive role on the change of vibration frequency. The errors between the tension force obtained by experiment and tension string theoretical calculation for short suspenders are large, due to the nonrigid boundary condition. The establishment of quadratic regression relationships between vibration frequency and tension force effectively avoids the influence of various factors on the existing calculation model such as mass, stiffness, and constraint type, and makes the detection accuracy of tension force achieve 98%. [ABSTRACT FROM AUTHOR]

In this study, factors affecting average shot velocity in the Surface Mechanical Attrition Treatment (SMAT) process were investigated numerically. The numerical model was developed by using the finite element method. The effects of frequency, amplitude, and projection distance parameters on shot velocity were simulated. Response Surface Methodology (RSM) was used to evaluate the simulation results. ANOVA tables were used for statistical evaluation. Moreover, the regression equations derived from simulation results were compared with the theoretical equations. Besides, the effect of the amount of shot in the SMAT chamber on the velocity of the shot is simulated. The results showed that apart from frequency and amplitude, projection distance also had a significant impact on shot velocity. [ABSTRACT FROM AUTHOR]

One of the important processes taking place during soil surface tillage is the variation of the soil temperature at different depths. The paper presents the results of research into the dynamics of soil temperature variation in terms of such parameters of the soil as its thermal diffusivity and temperature oscillation frequency. It has been established that the temperature oscillation amplitude decreases when the depth increases, following the logarithmic law. In this variation, the temperature difference between the 0–5 cm layer and the adjacent 5–10 cm layer has the greatest value. This circumstance is a favorable factor for the fallow tillage technology, where the soil is regularly cultivated to a depth of no more than 5 cm, in case of a moisture deficit. A decrease in the frequency of the soil temperature oscillations can result in the reduced level of its heating in different layers. In terms of qualitative changes, the reduction in soil thermal diffusivity results in the amplitude of the soil temperature oscillations being lowered and at the same time the maximum of these oscillations being shifted towards a delay. [ABSTRACT FROM AUTHOR]

Modifying the metaheuristics as a striking alternative of basic algorithms is outstanding and efficient scientific approach in optimization of engineering problems to improve robustness and convergence rate. Firefly algorithm (FA) is one of the new metaheuristics inspired by the flashing behavior of fireflies, where the performance of each randomly generated solution on objective function is evaluated by the brightness. In the current paper, a modified firefly algorithm (MFA) was introduced using expectation value and generalized weighted average of a random brightness and then evaluated with different benchmark functions. Since brightness varies with movements of fireflies, the parameter settings can adaptively be tuned for different problems. The capability of the MFA then in hybridizing with a developed automated multi-objective radial-based function network (MORBF) was examined. In blasting engineering, multi-objective models covering the peak particle velocity (PPV) and the vibration frequency (Fvib) due to providing more insight on safety criteria significantly are essential and great of interested. The hybrid MORBF-MFA then was applied on 78 blasting data comprising stemming, burden, spacing, total charge, distance, and charge per delay to provide more accurate predictive model. Detailed executed analyses through different metrics showed 1.01% and 2.43% improvement in hybrid MORBF-MFA corresponding to PPV and Fvib over MORBF-FA. The observed results approved that the introduced MFA as a reliable and feasible tool with accurate enough response can effectively be applied to multi-objective problems. Implemented sensitivity analyses scored the distance and burden as the most and least influences factors on predicted outputs. [ABSTRACT FROM AUTHOR]

At a high frequency of vibration; the cam of a vibrator always encounters the issue of jamming or the follower rolling off or losing contact with the cam when the appropriate design is not carried out. This study, therefore, developed the shape of the cam profile of mechanical yam vibrator using cycloid motion in the South. Displacement equations from the base circle to the cam profile were developed to obtain the shape of the cam using cycloid motion. A vibrometer was used to evaluate the developed 5 mm, 10 mm, and 20 mm cam sizes installed in a mechanical yam vibrator. The maximum displacement recorded for 5 mm, 10 mm and 20 mm cam sizes were 4.47 mm, 8.71 mm, and 14.54 mm respectively for low (1 - 5 Hz) frequency; 4.58 mm, 8.84 mm and 16.34 mm respectively for medium (60 - 100 Hz) frequency; and 4.66 mm, 9.09 mm and 17.30 mm respectively for high (150 - 200 Hz) frequency. This study shows that a cycloid cam would operate smoothly at low, medium, and high frequencies of vibration and function properly for frequency and displacement of vibration up to 200 Hz and 20 mm respectively without jamming and failing. A cycloid cam is therefore recommended for low, medium, and high frequencies motion of vibration. [ABSTRACT FROM AUTHOR]

In present paper, we consider the impact of blast-induced vibrations on constructions by analyzing the blasting results at limestone quarry Hardovac near Doboj (Bosnia & Herzegovina) recorded in period 2012–2015. Analysis is conducted using the multiple linear regression (MLR) and artificial neural networks (ANN) for establishing the correlation between the peak particle velocity, vibration frequency and several controlling factors (number of boreholes and their average depth, distances between the boreholes, between the arrays of boreholes and between the blasting and recording point, total and immediately detonated amount of explosive). As a result, we formulate explicit nonlinear models for estimation of safe distance between blasting points and different neighboring structures, including the construction of safe distance isolines. Suggested approach provides results which are comparable to the commonly used techniques but indicate the important effect of the examined controlling factors on safe distance, which is usually underestimated in common practice. [ABSTRACT FROM AUTHOR]

Anisotropy parabolic potential (APP) effects on ground state (GS) energy E 0 and the vibration frequency (VF) λ of weak-coupled magnetopolaron (MP) in asymmetric Gaussian quantum wells (AGQWs) were investigated using the linear combination operator and unitary transformation method. The obtained results showed that E 0 and λ were increased by increasing the barrier height V 0 of AGQWs as well as transverse and longitudinal confined strengths ω x and ω y of APP and decreased with increase in the asymmetric Gaussian confinement potential (AGCP) range R and transverse and longitudinal effective confined lengths l x and l y of APP. Thus, the GS energy and VF of MP could be changed by adjusting the confinement parameters of the APP and AGCP. The study of quantum wells' semiconductor materials has broad potential applications in semiconductor lasers, optoelectronic devices and quantum information. [ABSTRACT FROM AUTHOR]

Ultrasonic vibration technology has great potential to weaken hard rocks. Understanding the effect of ultrasonic vibration loading parameters is essential to accelerate the application of this technology in practical rock engineering. In the present work, three-factor mixed-level orthogonal ultrasonic vibration rock breaking tests were conducted to investigate the influence of the main loading parameters, including confining pressure, vibration frequency, and static force, on the damage of granite specimens. The individual and combined influences were analyzed according to the porosity increase and P-wave decrease of granite specimens using the variance analysis method. The results show that the combined effect of the static force and vibration frequency mainly promotes fatigue damage of specimens, that the confining pressure determines the damage behaviour and failure mode of specimens under ultrasonic vibration, and that the confining pressure and vibration frequency are the main factors that cause the fracture concentration in the upper part of specimens, an effect mechanistically driven by the obvious load energy attenuation. The research results provide theoretical guidance for the application of ultrasonic vibration technology. [ABSTRACT FROM AUTHOR]

In this article, a rotary valve is developed to obtain accurate high-frequency sinusoidal vibration waveforms. Then, a uniaxial electro-hydraulic shaking table controlled by a set of parallel rotary valves is constructed, which can superpose the sinusoidal vibration waveforms. The non-sinusoidal vibration waveforms including triangular vibration waveform, rectangular vibration waveform, sawtooth vibration waveform and trapezoidal vibration waveform are generated by adjusting the spool rotation speed based on the Fourier series. The results show that with one rotary valve, the uniaxial electro-hydraulic shaking table can output accurate high-frequency sinusoidal vibration waveforms and the total harmonic distortion is less than 1% at high vibration frequency. Compared with the standard vibration waveform, the error of the generated vibration waveform is very small. For the rectangular vibration waveform and sawtooth vibration waveform, the error is less than 6%, and for the triangular vibration waveform and trapezoidal vibration waveform, the error is less than 3%. The impacts of the working conditions on the error of the generated vibration waveform are very small. The proposed method for the accurate high-frequency non-sinusoidal vibration waveform is very effective and can be applied in high vibration frequency and different load masses. With the increase of the supply pressure, the amplitude of the generated vibration waveforms increases, while the error changes in a rather narrow range. The amplitude can be adjusted by changing the supply pressure with almost no effect on the accuracy of the vibration waveform. [ABSTRACT FROM AUTHOR]

This work investigates the influence of tool surface area (TSA) on the average surface roughness ( R a) , tool wear rate (TWR) and material removal rate (MRR) in the micro-electrical discharge machining (μ EDM). The effects of three different TSAs were investigated at three different discharge energy settings. It was observed that the TSA had substantial influence on μ EDM performance owing to scaling effect. Therefore, the low-frequency workpiece vibration was applied to improve the μ EDM performance. The surface topography of machined surfaces was examined using scanning electron microscopy to disclose the effect of TSA as well as vibration frequency on μ EDMed surfaces. [ABSTRACT FROM AUTHOR]

Vibrations on imported fruits can cause one of the damage such as impact, wear and compression or a combination of them to the fruit. The nectarine fruit tissue is soft at the soft handling stage, which increases the susceptibility to mechanical damage during transportation and storage. In this study, the effects of simulated transport vibrations on the quality of nectarine fruit with five levels of frequency, three levels of displacement, two types of boxes, three types of adsorbent on the first, second and third rows of fruit have been studied. The root mean square vibration acceleration was considered as a measure of the vibration magnitude and the vibration transferability percentage was calculated in different treatments. In addition, the maximum stress and modulus of elasticity at the yield point were calculated. Results showed the absorbers had the highest and lowest vibration absorption in the frequency range of 5.7 to 7.5 and 8.9 Hz, respectively. The first, second and third rows of fruits had the lowest transmitted and the highest vibration absorption at accelerations of 0.8, 8.4 and 6 ms-2, respectively. The lowest vibration absorption was obtained in the first, second and third rows at accelerations of 2.3, 5.1 and 3.4 ms-2. Therefore, it is recommended to use cardboard boxes with paper absorbers inside to carry the fruit and do not place more than one row of fruit in each box. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

We studied the vibration frequencies of small double-clamped silicon nanobeams using a molecular dynamics method. The effects of cross-section area, size, and oxide layer were investigated through simulation. The results show that the vibration frequency decreases with increasing length, whereas it increases slightly with increasing cross-section area of the nanobeam. The existence and thickness of an oxide layer lead to increasing of the vibration frequency of silicon nanobeams. [ABSTRACT FROM AUTHOR]

In aircraft structures, auxiliary equipment in the form of antennas, sensors, observation devices, etc. are often attached to its lifting elements. These devices change the dynamic behaviour of the entire structure and they can bring it into a resonant state, since some additional partial spectra from the attached dynamic subsystems are superimposed on the spectrum of natural frequencies of oscillations of the carrier system. This increases the likelihood of resonant modes of motion. Therefore, the study of vibrations of composite structures is relevant and it is of significant practical interest. In the proposed paper, we consider a structure consisting of a shallow spherical shell (lifting system) and an additionally attached vertically standing rod. In addition to purely practical applications, the problem is also of purely scientific interest, since the individual components of the structure experience different types of oscillatory movements. The shell performs transverse (radial) vibrations, and the rod -- longitudinal. To solve the problem, two mechanical design models based on different variants of the structure idealisation are proposed. The first one of them is reduced to a one-stage oscillatory model (linear oscillator), which takes into account only the inertial properties of the rod, and the second one, in addition, also its elastic properties. In both versions of the solution, the shell itself retains only elastic properties, neglecting its mass characteristics. The stiffness of the equivalent springs that simulate the local compliance of the shell at the rod attachment point is determined on the basis of the classical theory of shells. The last problem itself is extremely time consuming, therefore its corresponding solution is taken from previously published scientific sources. [ABSTRACT FROM AUTHOR]