Resonant Vibration Research Articles

Spike propagation by synchronization and vibrational resonance in feedforward Izhikevich neural network

Spike propagation by synchronization and vibrational resonance in feedforward Izhikevich neural network

Photoelectron Imaging and Photodetachment Spectroscopy for the Cryogenically Cooled Cyanocyclopentadienide Anion.

The cyano-cyclopentadiene molecule (CN-C5H5) has attracted significant interest since its detection in the interstellar medium, but the radical (CN-C5H4) and anionic (CN-C5H4-) forms of cyano-cyclopentadiene have not been studied. The cyano-cyclopentadienyl radical (CN-Cp) has a strong dipole moment, rendering it an ideal system for vibrational and rotational spectroscopy. We report an investigation of the cryogenically cooled cyano-cyclopentadienide anion (CN-Cp-) using high-resolution photoelectron imaging, photodetachment spectroscopy, and resonant photoelectron imaging. The electron affinity of the CN-Cp radical is measured accurately to be 2.7741 ± 0.0003 eV (22,375 ± 2 cm-1). A low-lying excited state is observed for the CN-Cp neutral radical at 151 cm-1 above the ground state. The overlap and vibronic coupling of the ground and low-lying electronic states give rise to complicated and congested photoelectron spectra. A dipole-bound state is observed for the CN-Cp- anion with a binding energy of 94 cm-1, along with 15 vibrational Feshbach resonances. Resonant photoelectron spectra via the vibrational resonances yield well-resolved spectra, allowing 26 vibronic levels to be identified for CN-Cp. The rich spectroscopic information will be valuable to compare with theoretical studies to unravel the vibronic coupling and nonadiabatic effects in the CN-Cp radical.

Tuning of a Viscous Inerter Damper: How to Achieve Resonant Damping Without a Damper Resonance

Inerter dampers are effectively employed to mitigate and dampen structural vibrations in slender or high-rise buildings. The simple viscous inerter damper, with a viscous dashpot placed in series with an inerter, is designed to create resonant vibration damping, although the damper itself is without an internal resonance. The apparent resonant behavior is instead obtained by increasing the damper inertance until the two lowest modes of the considered building model interact, whereafter the viscous coefficient is adjusted until the desired response mitigation is achieved. The present modal interaction tuning requires that the reduced-order single-mode dynamic model of the building includes both inertia and flexibility from the (other) modes otherwise discarded by the model reduction. While the inertia correction adjusts the modal mass of the inerter damper, the corresponding flexibility introduces the apparent damper stiffness that creates the desired damper resonance. Thus, the accurate representation of other modes is essential for the design and resonant tuning of the simple viscous inerter damper. The resonant damper performance by the non-resonant viscous inerter damper is illustrated by a numerical example with a 20-story building model, for which the desired resonant modal interaction requires an inertance of almost ten times the entire translational building mass.

Synthesis, single crystal culture, activation energy calculation and HMBC spectrum of 1-methyl-1,2,4-triazole-3-carboxylic acid methyl ester and its positional isomers

Ensitrelvir is a 3CLpro inhibitor developed by SHIONOGI & CO., Ltd. of Japan for the treatment of COVID-19 and was approved for marketing in Japan on November 1, 2022. Various research results show that compared with Pfizer's Paxlovid and Merck's molnupiravir, Ensitrelvir is currently the most effective, safest and longest-lasting drug in the world! The synthesis of ensitrevir can be divided into four segments, and the docking of these four segments. Among them, the challenging segments are the triazole and indole segments due to the issue of methylation selectivity. In this study, DFT theory was primarily employed to investigate the activation energy of 1-methyl-1,2,4-triazole-3-carboxylic acid methyl ester and its positional isomers under different solvent conditions. Through experimental screening, selective methylation of 1H-1,2,4-triazole-3-carboxylic acid methyl ester was achieved. Subsequently, single crystals of the main product were cultivated, and calculations of electron density, nuclear magnetic resonance vibrations, etc., were performed for the three products to study the differences in the properties of various methylation products. Further structural confirmation of the three compounds was carried out using HMBC two-dimensional spectra.

Vibrational resonance and chaos control in the canonical Chua’s circuit with a smooth nonlinear resistor

Vibrational resonance and chaos control in the canonical Chua’s circuit with a smooth cubic nonlinear resistor is investigated by an analog circuit experiment and a dynamical model. By adjusting the amplitude and frequency of the high-frequency signal while keeping other parameters constant, the system exhibits a resonant peak in its response to the weak low-frequency signal. Notably, when the amplitude of the high-frequency signal exceeds the critical threshold, the system undergoes a transition from a single-scroll chaotic attractor to a double-scroll chaotic attractor, marking the emergence of vibrational resonance. In particular, the maximum of the system’s response amplitude is insusceptible when the frequency of the high-frequency signal varies over a broad range, which indicates the strong robustness of the vibrational resonance in the present system. The experimental results are coincident with the numerical simulations. This research has potential applications in chaos control and weak signal detection.

Microstructure Embossing Patterning Using Resonated Droplets Dynamic Behavior Induced by Vertical Vibration

AbstractThis paper introduces a novel, ecofriendly, and cost‐effective method to create deformation patterns on vertically vibrating thin film surfaces using resonant sessile droplets. The key findings emphasize the critical role of resonant frequency and vibration velocity in the formation of these deformations. Through theoretical and experimental investigations on aluminum thin film, it is validated that the deformations are influenced by the energy distribution within the resonant droplets. Specifically, higher‐order resonant frequencies produce a more concentrated energy distribution at the droplet's center due to internal top‐down flow behaviors, resulting in various deformation states. By observing regularities in deformation width patterns, the underlying phenomena are elucidated, and derive related empirical formulas. This method demonstrates significant potential for surface microstructure fabrication. The ability to control deformation shapes by adjusting vibration parameters is crucial for optimizing microfabrication processes.

Spectroscopy and Dynamics of the Dipole-Bound States of ortho-, meta-, and para-Methylphenolate Anions.

A photodetachment and photoelectron spectroscopic study by employing a cryogenically cooled ion trap combined with a velocity-map imaging setup has been carried out to unravel the vibrational structures and autodetachment dynamics of the dipole-bound states (DBSs) of o-, m-, and p-methylphenolate anions (o-, m-, and p-CH3PhO-). The electron binding energy of the DBS increases monotonically with the increase of the neutral dipole moment to give respective values of 66 ± 15, 123 ± 18, or 154 ± 14 cm-1 for the o-, m-, or p-isomer. The different electron-donating effects of the methyl moieties in the three geometrically different isomers seem to be reflected in the experiment. Mode-specific DBS dynamics of the o-, m-, and p-CH3PhO- complexes have been interrogated by using picosecond time-resolved photoelectron velocity-map imaging spectroscopy. Autodetachment lifetimes of the DBS vibrational Feshbach resonances have been measured and discussed quantitatively using Fermi's golden rule, especially in comparison with those of the phenoxide anion to get insights into the methyl substitution effect on the electron binding dynamics of the metastable DBS.

Psychological health in health care workers: features of the formation of professional burnout, prevention opportunities

Introduction. The working conditions in medical workers are characterized by high tension, which leads to a violation of the psycho-emotional state in health care workers, including professional burnout, the features of which depend on the neurophysiological type of personality, the severity of chronic stress, and the level of commitment to a healthy lifestyle. The purpose is to identify risk factors for professional burnout and evaluate the effectiveness of preventing professional burnout in medical workers in conditions of increased work intensity. Materials and methods. The study included medical workers with indices of the intensity of the labour process of class 3.1 and 3.2. The questionnaire method was used to determine: the features of the formation of professional burnout, characteristics of the type of nervous system, the index of adherence to a healthy lifestyle, stress level, subjective assessment of the psychological state. The analysis of the trend in indices of professional burnout and psychological state after group psychosomatic correction sessions was carried out. Results. The structure of professional burnout in medical workers was dominated by high rates of reduction of professional achievements (53.8%), the frequency of emotional exhaustion was 25.6%, depersonalization – 30.8%. The probability of developing emotional exhaustion in persons with an average strength of the nervous system was 3.8 times higher than in persons with a strong type of nervous system. A lack of commitment to a healthy lifestyle is associated with an increased frequency of emotional exhaustion. The positive trend in indices of professional burnout and subjective assessment of the psychological state after the preventive program of resonant acoustic vibrations has been achieved. Limitations. The subjects were employees of a medical institution working under conditions of exposure to the intensity of the labour process exceeding hygienic standards. The data is limited to voluntary study participants. Conclusions. The features of the formation of professional burnout in medical workers are determined. The effectiveness of the program for the prevention of professional burnout with the use of group psychosomatic correction has been confirmed.

Single-Path Supercontinuum Near- to Mid-Infrared Correlation Spectroscopy of Aqueous Samples.

Combining near-infrared (NIR) and mid-infrared (MIR) spectroscopy to cover both the fundamental and overtone combination molecular vibrational resonances allows more robust analytical methods to be used, such as two-dimensional correlation spectroscopy. However, due to the strong differences in molar absorption coefficients and transparency of the optical material, it is inherently difficult to perform NIR and MIR spectroscopy on aqueous samples using a single instrument. Combining spectra from different instruments and sample presentations can result in unwanted spectral variations, which can influence the prediction models and mitigate the advantages of the combination approaches. In this work, a more consistent instrument response is achieved by combining a single supercontinuum (SC) laser spanning from 1000 to 4000 nm as the light source, with an attenuated total reflection crystal and a transmission cuvette in a single-path configuration. Using this approach, NIR-MIR correlation spectroscopy is demonstrated using a set of 22 aqueous samples with varying concentrations of ethanol, sucrose, and ʟ-proline.

Two-Dimensional Simulation of Generalized Thermoelastic Damping in Vibrations of Strain Gradient Beam Resonators

The operation of micro/nanobeam resonators is greatly impacted by the thermoelastic damping (TED) phenomenon, highlighting the need for precise determination of its value. Given the confirmed size effects in both mechanical and thermal fields, along with the importance of utilizing the two-dimensional (2D) heat transfer model over the 1D model for more accurate simulation of the thermomechanical behavior of small-scale beams, this paper aims, for the first time, to present a 2D model for TED using the modified strain gradient theory (MSGT) and the nonlocal dual-phase-lag (NDPL) heat equation. To accomplish this, the 2D NDPL-based temperature distribution is calculated using the Galerkin method, while the MSGT is applied to determine the size-dependent constitutive equations. The obtained relations are then used in the energy dissipation (ED) method to derive a TED formula in the form of infinite series. To validate the model’s accuracy, a simplified version is employed for comparison. A detailed convergence study is also performed to determine the optimal number of terms needed for precise results. Finally, a thorough parametric analysis is undertaken to explore how key factors like 2D heat transfer and non-classical constants in the MSGT and NDPL model impact TED. The findings highlight the importance of using the MSGT and NDPL model in micro- and sub-micro dimensions, and the need for the 2D model in beams with low aspect ratios.

Grain refinement and mechanical properties improvement of AlCuFeCoNi high-entropy alloy coatings fabricated by resonant ultrasonic assisted laser cladding

Laser cladding technology has gained significant popularity for the preparationof high-entropy alloy (HEA) coatings. This is primarily due to its notable benefits, such as a low dilution rate and a robust bonding capability. However, the laser cladding process’s rapid solidification effect and the high entropy impact led to the formation of defects in the coatings, such as non-uniform organization and elemental segregation. In this paper, the resonant ultrasonic vibration was used to regulate the organization and improve the microhardness and friction properties of the AlCuFeCoNi HEA coatings. The experimental findings demonstrate that ultrasonic vibration enhances both the width and depth of the coating’s molten state, while simultaneously reducing the height of the coating. Before and after the introduction of ultrasonic vibrations, the coating consists of two phases, body-centered cubic (BCC) and face-centered cubic (FCC). However, the magnitude of the FCC phase significantly increased with higher power. The internal grains of the coating were significantly refined by ultrasonic vibration, and the average grain size was refined from 68.34 μm to 35.28 μm, and the area occupied by equiaxial grains also increased with the increase of ultrasonic power, and the segregation of the FCC phase dominated by Cu elements was suppressed. When the ultrasonic power was 30 %, the microhardness of the coating was increased from 553.19 ± 5.15 HV0.2 to 600.47 ± 3.61 HV0.2. The addition of ultrasonic vibration increased the wear resistance of the coating and lowered the coefficient of friction from 0.558 to 0.409. Furthermore, the friction mechanism of the coatings before and after the addition of ultrasonic vibration did not change, and both were abrasive wear with slight oxidative wear.

Experimental investigation and modelling of the noise and vibration in screw compressors

Abstract This article presents work on the extension of torsional models development for screw compressors. These compressors are common in industry and their vibration behavior and signature are very important. When neglected in the design, it can lead to torsional or structural resonance or lateral vibration in the machine during operation and in the worst case to catastrophic failure of the machine. The screw compressors presented here are used for bulk transport on trucks. They are designed and built by CVS Engineering GmbH. Measurements in the lab and field test showed that the torque peak in the drive shaft can fluctuate and show large values than normal when the first torsional mode is excited by 1 × the input speed. They also show that the nature of the excitation and hence the response of the machine depends on the drive and the excitation amplitude, which depends strongly on the prop-shaft angle. To predict this behavior, detailed free and forced torsional models are developed and validated with measurements. The latter enables the validation of the torque peaks obtained in measurement. The drive train configuration (branched or unbranched) is

Parametric vibrational resonance and multistability in biharmonically driven Briggs-Rauscher chemical system

Parametric vibrational resonance and multistability in biharmonically driven Briggs-Rauscher chemical system

An novel algorithm of vibration resonance control for power ultrasonic device via extremum seeking control based maximum conductance searching

The vibration control based on the resonance frequency tracking (RFT) to the piezoelectric transducer is critical for an ultrasonic device. The speed and accuracy of the RFT is significant to ensure the resonant vibration and transmit enough ultrasonic power in real time and high electrical-acoustic energy transform efficiency. Conventionally, the RFT methods is based on the Phase Locked Loop (PLL) and or the maximal current feedback. More, it need to measure the parallel static capacitor, which is difficult to achieve in the circuit or hardware component. In this investigation, we propose a novel algorithm to fast control the resonant vibration based on the RFT method by using the admittance circle model. In the proposed method, the model of the admittance circle of the transducer is established, following the the maximum conductance value in the admittance circle is accurately searched. In order to fast and accurately lock the optimal resonance frequency, we adopt the extremum seeking control (ESC) to find the maximum conductance value. The admittance circle model and the RFT based on ESC is validated by the simulation. We setup an experimental platform based on DSP-FPGA controller to verify the above algorithm, and the results proves that our proposed method can lock the mechanical frequency and control the resonance vibration of the power ultrasonic device in 15 ms. Moreover, in our RFT algorithm, it is no need to measure the parallel static capacitor of the transducer, which can ensure the high energy output.

Analysis of Vibrational Resonance in a Parametric Quintic Oscillator with Double-Well Potentials

Analysis of Vibrational Resonance in a Parametric Quintic Oscillator with Double-Well Potentials

Dual-Vibration-Assisted Charge Transport Through Hexabenzocoronene in Single-Molecule Junctions.

Gaining deep understanding and effective regulation of the charge transport mechanism within molecular junctions is essential for the development of electronic devices. In this work, a series of hexabenzocoronene-based single-molecule junctions are successfully constructed, and their temperature-dependent charge transport properties are studied. It is found that rotational vibrations of both benzene and hexabenzocoronene rings are sequentially excited as the temperature increases, and the electron-vibration coupling enhances charge tunneling. In addition, the transition temperature between distinct vibration-assisted tunneling modes and the activation energies showstrong correlations with the molecular vibration frequency and molecular length. This study unveils the distinct dual-vibration-assisted molecular tunneling mechanism, significantly enhancing the ability to precisely control molecular charge transport and develop functional molecular devices.

Exploring the abnormal vibration of SEG Plaza via wind-tunnel substructure hybrid simulation

In May 2021, the SEG Plaza in Shenzhen of China experienced abnormal vibrations, which aroused widespread social concern. The reason of the vibrations is summarised as follow: the wind load causes the vortex-induced vibration of the masts located at the top of the building, which in turn results the resonance vibration between the masts and the building. To reproduce the abnormal vibration, the field measurements were carried out to obtain the modal information of the building and the masts firstly. Wind-tunnel substructure hybrid simulation (WTSHS) was proposed to reproduce the abnormal vibration of SEG Plaza. In WTSHS, the outer skin of the cantilever section of the masts is taken as the experimental substructure and modelled by rigidity compression wind-tunnel test. A multi-degree-of-freedom (MDOF) model of the building incorporating the dynamic characteristics (MDOF model) of the cantilever section of the masts is considered as the numerical substructure. The bottom layer force of experimental substructure was calculated and fed back to the numerical substructure to obtain the acceleration response of the building and masts. Ten test conditions of WTSHS with different wind angle (0°-90°) were conducted to reproduce the acceleration responses at specific location, which are close to the acceleration response obtained from the field measurements. The WTSHS's capability to replicate the wind-induced vibrations in buildings offers a novel experimental approach to investigate the dynamic responses of tall structures in the future.

INFRARED FOURIER SPECTROSCOPY OF DIFFUSE REFLECTION OF THE AZ nLOF SERIES NEGATIVE PHOTORESISTS FILMS ON MONOCRYSTALLINE SILICON

Films of the AZ nLOF 2020, AZ nLOF 2070 and AZ nLOF 5510 negative photoresists (PR) with a thickness of 0,95 – 6,1 μm, deposited on the surface of silicon wafers by the centrifugation method, were studied by the method of IR-Fourier diffuse reflection spectroscopy. In the diffuse reflectance spectra of PR/silicon structures, absorption bands were observed against the background of interference fringes. It allows the technique to be used to measure film thickness or its refractive index. The most intense bands in the AZ nLOF series PR spectra are the bands of stretching vibrations of the aromatic ring, pulsation vibrations of the carbon skeleton of the aromatic ring, a wide structured band with several maxima in the range of 1050 – 1270 cm–1 and a band associated with the CH2 bridge. The structure of the absorption spectrum of photoresists of the AZ nLOF series is similar to the structure of the spectrum of phenol-formaldehyde photoresist FP9120. It was shown that the vibration band of CH3 groups at 2945 cm-1 is due to the solvent.

A wide-frequency triboelectric vibration sensor for self-powered machinery health monitoring

Abnormal vibration is usually a precursor to structural damage and performance degradation industrial equipment and transportation. Vibration detection at critical locations such as electrical motors and bearings within large equipment has emerged as an indispensable method for machinery health monitoring. Current vibration detection instruments mostly need to be powered by cables or batteries, which has application limitations in complex moving equipment and restricted space. In this paper, a disc-like triboelectric nanogenerator (DL-TENG) with a multi-sized honeycomb structure is proposed as an innovative solution for achieving wide band and high precision acceleration detection of the vibration. Multi-diameter polytetrafluoroethylene (PTFE) balls are used as friction materials to achieve the high voltage output of the TENG, providing sufficient energy for the detection circuit. By carefully designing suitable honeycomb structures for PTFE balls of different diameters, the ability to detect broadband vibration signals is obtained. The experimental results demonstrate that DL-TENG with honeycomb structure and multi-size PTFE balls can detect acceleration signals ranging from 10 to 2000 Hz, and the acceleration measurement range can reach 1–11 m/s2 with an acceleration resolution of 0.1 m/s2. Moreover, DL-TENG can output more than 80 V peak-to-peak under vibration conditions of 11 m/s2. And under vibration conditions of 8 m/s2, the DL-TENG can fully charge a 100 μF capacitor to 5 V in just 100 seconds. By equipping a special circuit for DL-TENG, wireless self-powered vibration detection is realized. This study is expected to be applied in the scenario of vibration information collection in complex ring vibration environment and provides a new paradigm for the realization of self-powered vibration sensors.

Numerical analyses of acoustic vibrational resonance in a Helmholtz resonator

AbstractIn this study, the numerical analyses of a system, which describes the motion of air particles in the cavity of a Helmholtz resonator (HR), excited by a sound wave, was conducted. The low-frequency (LF) signal in the acoustic field is amplitude-modulated by an additive high-frequency (HF) perturbation, which can enhance the detection of the low-frequency, through Vibrational Resonance (VR) phenomena. The focus was on the combined effect, of amplitude and frequency of the acoustic excitation, on the motion of particles and induction of resonance. It was demonstrated that the system exhibits several nonlinear behaviours, VR ceasing to exist for a particular motion of the particles, which is dictated by the excitation frequency in relation to the resonator’s geometry. Furthermore, the regimes in which the performance of the system can be optimized, was identified, which facilitated the design of broadband acoustic resonators, suitable for most applications.