Calculation Of Resonant Frequencies Research Articles

Simultaneous determination of Young's modulus and residual stress via dynamic analysis of nanobridge exhibiting beam-to-string behaviors using a genetic algorithm

The mechanical properties of nanostructures, particularly Young's modulus and residual stress, exert significant influence on the performance and reliability of nanomechanical devices. However, conventional methods prove inadequate for evaluating these properties due to the impact of fabrication processes on nanostructures. This study addresses this challenge by proposing a dynamic model that considers the transition between “beam-like” and “string-like” characteristics under residual stress, a factor overlooked in previous research. Through analysis of nanobridge vibration modes and utilization of genetic algorithms (GAs) to reverse-engineer Young's modulus and residual stress from resonant frequencies, we introduce a novel and precise methodology. In contrast to the conventional Euler-Bernoulli beam theory, our proposed model integrates the system's kinetic and potential energies for resonant frequency calculation. This energy-based approach, grounded in physical principles, excels at capturing dynamic changes in structural behavior. Particularly in the critical “transition region” where the resonator shifts from “beam-like” to “string-like” behavior, our method adeptly accounts for energy conversion processes, resulting in more accurate resonant frequency estimations. By comparing with existing published data, our proposed method achieves a maximum error of 5.87 % in the determination of Young's modulus and residual stress of nanostructures.

Wave scattering problems in exterior domains with the method of fundamental solutions

The method of fundamental solutions has been mainly applied to wave scattering problems in bounded domains and to our knowledge there have not been works addressing density results for general shapes, or addressing the calculation of the complex resonance frequencies that occur in exterior problems. We prove density and convergence of the fundamental solutions approximation in the context of wave scattering problems, with and without a priori knowledge of the frequency, which is of particular importance to detect resonance frequencies for trapping domains. We also present several numerical results that illustrate the good performance of the method in the calculation of complex resonance frequencies for trapping and non trapping domains in 2D and 3D.

Resonant ultrasound spectroscopy applications: Elastic moduli computation with x-ray computed tomography input for irregularly shaped objects.

Resonant ultrasound spectroscopy is a technique that uses a combination of experimentally measured resonant frequencies and physics-based computation of these frequencies to determine the entire set of single crystal elastic moduli of the material. Computation of the resonances is most often accomplished using the Rayleigh-Ritz energy minimization technique, and a basis function that requires sample with canonical geometry, such as a cylinder or a rectangular parallelepiped. Any deviation from canonical geometry can have a significant impact on the calculated resonance frequencies and the inverted elastic moduli. To overcome this limitation, this paper describes an approach that uses x-ray computed tomography data to generate accurate solid part model of components with complex geometry. The part model is then imported into an off-the-shelf finite element method (FEM) software to perform the forward problem. The FEM was combined with surrogate modeling for computation of resonance frequencies of both canonical and non-canonical samples, and ultimately, the inversion of elastic moduli.

Investigation on multiple-frequency resonant characteristics of a Helmholtz resonator with an extended neck

Helmholtz resonator (HR) is widely used in various fields, but the classic HR usually should satisfy the acoustically compact condition, which limits the application range of the classic HR. This paper investigates analytically and numerically the acoustic performance of a HR in which the length of the neck is not limited under the acoustically compact conditions. An analytical model is developed for accurately and quickly predicting resonant frequencies and transmission loss of the Helmholtz resonator with an extended neck (HREN), and numerical simulations have been performed to validate the developed analytical model. Both the analytical and numerical studies reveal that the HREN has multiple resonant frequencies, and a method is developed for approximate and fast calculation of the multiple resonant frequencies.

UWB Microstrip Patch Antenna Design for Energy Harvesting Applications

RF energy harvesting systems, which are the receiver part of Wireless Power Transfer (WPT), have gained significant development in recent years. For maximum energy acquisition over a wide frequency range, such as to provide power to small handheld devices like cell phones, tablets, smart watches, and other smart devices, wideband and compact antennas are desired. RF systems are expected to cover different frequency bands, such as 2.4 GHz, 5.1 GHz, 5.8 GHz (Bluetooth/Wi-Fi), 2.3 GHz, 2.5 GHz, 3.5 GHz, 5 GHz (WiMAX), for energy harvesting. For such an RF harvesting system, the antenna is desired to have a wide bandwidth, good gain, and an omnidirectional radiation pattern. Energy harvesting devices refer to designs that integrate production and storage. For instance, radio frequency energy sources contain a large amount of electromagnetic energy in the environment, and with RF energy harvesting systems, a portion of this electromagnetic energy can be collected and converted into usable DC voltage. Microstrip patch antennas are very good alternatives for energy harvesting applications because they are cost-effective, compact in size and weight, flat in structure, and highly repeatable. This paper presents a microstrip patch antenna with a bandwidth of 3.9 GHz in the 3.4 to 7.3 GHz range for UWB applications. The antenna design has a gain value of 3.28dBi at the numerically calculated resonance frequency of 4.9 GHz and generally covers frequencies used for electronic device communication such as Wi-Fi 5 GHz and WiMAX. The proposed antenna design has gain values that are allowed to be used for RF energy harvesting applications.

Design of Hexagonal Ring Wearable Textile Antenna using Polyester for Early Bone Health Detection

In this research manuscript, the author proposes an innovative solution for monitoring and preliminary detection of bone health with the use of a newly designed Hexagonal Ring Wearable Textile Antenna (HRWTA) using polyester material. The HRWTA is designed and fabricated using polyester conductive electro-textile as radiating fabric and polyester fabric as substrate having dielectric constant of 1.44 with loss tangent of 0.01. The motivation behind this work stems from the increasing number of osteoporosis cases around the world has led to a greater need for new, non-invasive ways to keep track of bone health. Leveraging advancements in microwave technology and antenna design, this study introduces a novel approach by drawing parallels between hexagonal ring and annular ring microstrip antennas, resulting in a precise empirical formula for resonance frequency calculation [9]. Rigorous validation through simulations and experiments showcases the antenna's accuracy in assessing bone health parameters. HRWTA, born from this formula, offers a discreet and affordable means for continuous bone health monitoring, holding significant promise for early intervention and improved healthcare outcomes in the face of the growing osteoporosis challenge. The return loss bandwidth of HRWTA is 350 MHz (3.39 GHz-3.74 GHz, 10%). Also, it has a peak gain of 2.5 dB at 3.5 GHz. Hence, HRWTA is suitable for wireless body area network (WBAN) as it has good radiation characteristics.

Robust algorithm of indirect tyre pressure monitoring system based on tyre torsional resonance frequency analysis

• Detects changes in tyre pressure by monitoring changes in tyre resonance frequency. • Eliminating the disturbances of engine and driveline on frequency estimation. • Key parameters for evaluating tyre torsional vibration characteristics is proposed. • Methods proposed to compensate for the effects of road roughness and ambient temperature. • The proposed algorithm improves the robustness of frequency estimation. This paper focuses on an indirect Tyre Pressure Monitoring System (TPMS) algorithm based on frequency analysis of tyre torsional vibration. Tyre vibration is analysed using a tyre structure model, and the tyre resonance frequency is estimated using an Autoregressive (AR) model. The vibration disturbances from the engine and driveline that affect the estimation of the tyre torsional frequency are analysed, and a notch filter is designed to eliminate the disturbances. The torsional vibration of the driveline is identified by the correlation analysis of driving wheel speed. Two qualitative evaluation indexes of tyre torsional vibration characteristics are proposed. The corresponding quantitative parameters are used to determine the tyre torsional vibration state to eliminate the interference of undesirable vibration states on the frequency calculation. A road roughness estimation method is proposed based on tyre vertical vibration information in the wheel speed. The estimated road roughness parameters compensate for the calculated resonance frequency affected by road roughness. Based on the relationship between measured resonance frequency and temperature under a constant tyre pressure condition, the frequency variation value affected by tyre rubber stiffness variation due to temperature variation is calculated using the ambient temperature signal. The calculated resonance frequency is corrected to eliminate the coupling effect of gas stiffness and rubber stiffness, the impact of temperature variation on tyre pressure estimation is compensated. The results of vehicle road tests demonstrate the robustness of the proposed tyre pressure monitoring algorithm.

Design and performance evaluation of steel beam members with plate‐type locally resonant metamaterials for vibration control

AbstractIn this study, a plate‐type locally resonant metamaterial (PTLRM) is proposed to control bending vibrations and low‐frequency noise of civil members. Considering the ease of design, installation, and workability, the PTLRM was fabricated using high‐density and soft materials. The PTLRM design includes a resonance frequency calculation of the unit and band gap estimation of the PTLRMs‐coupled structure. Three indicators were developed and experimentally analyzed to evaluate the vibration attenuation performance of the PTLRM: the response suppression in the resonance of PTLRMs, peak response suppression ratio, and distance between peaks. Experimental results of a 5‐m long steel beam with PTLRMs indicated that the bending modal responses of the steel beam were suppressed at frequencies closer to the local resonance of the PTLRM. This showed reasonable agreement with the results of the estimation. The acceleration of the PTLRMs‐coupled beam was reduced by up to 98.58% in the frequency response function. The time history of acceleration also decreased significantly over the entire time period. The damping of the soft material had little effect on the bandwidth of the band gap. However, it was found that a proper increase in the damping of the soft material could increase the vibration suppression performance.

Study on vibro-acoustic characteristics of bamboo-based angklung instrument

The frequency (or pitch) content of bamboo angklung musical instruments was analyzed. The pitch of the rattle tubes was determined via a Pico oscilloscope recording both the time and frequency spectrum. Fast Fourier transform analysis identified the fundamentals and overtones of the individual tubes, which were compared with the calculated theoretical resonance frequency. The pitch, due to the coupling effects of two rattle tubes, slightly varied from the pitch of the individual rattle tubes. Although both rattle tubes (played simultaneously) displayed the fundamental frequencies in both tubes, the individual tubes played separately did not produce the exact frequency obtained from both tubes played simultaneously. The spectrum of both tubes produced sound output from the individual tube, which is shown by two prominent peaks, corresponding to the pitch of the individual tube. Although the long and short tube show an individual fundamental frequency of 528 Hz and 1095 Hz, respectively, for C5 tube (when played separately), the coupling of both tubes produced the first and second peaks (when played simultaneously) at 546 Hz and 1093 Hz. Due to the disparity of the fundamental frequency, the inner diameter and length of the tube was utilized for the theoretical resonance frequency calculation.

Analysis of damping characteristics for damped plate with a crater type acoustic black hole using modal strain energy method(Effects of residual plate thickness)

This paper deals with vibration damping analysis using finite element method with Model Strain Energy Method for a plate with a crater type acoustic black hole. The acoustic black hole has residual plate thickness. The 3Dmodel were created by using 3DCAD software and the 3D model was made into a finite element model using analysis modeling software called HyperMesh and then analyzed using FEM with Model Strain Energy Method to calculate the resonant frequency and mode loss coefficient for each mode. We calculated resonance frequencies and modal loss factors in each mode. For comparison, we also prepared a crater type acoustic black hole with no residual plate thickness. Effects of residual plate thickness on vibration damping properties were investigated. As a result, those having a residual plate thickness had a higher overall damping effect than those without residual plate thickness, and a very high attenuation effect could be obtained, especially in the high frequency range.

A novel wideband multi‐mode coupled resonator filter based on bulk acoustic wave technology

This paper proposes a novel multi-mode bulk acoustic wave (BAW) coupled resonator filter (CRF) for wideband applications. Three stepped-impedance coupling layers of CRF are used to generate multi-mode properties, and external inductors are added for port match. To facilitate the calculation of resonance frequencies, a simplified Mason model is derived and applied in the even- and odd-mode analysis of CRF. Based on different acoustical length of CRF coupling layers, four cases that are applicable for different filter bandwidth are proposed. From these cases, fractional bandwidth (FBW) of the multi-mode CRF can be realized in a wide range from 12.8% to 33% when the coupling layers adopt the commonly used SiO2/Mo/SiO2 materials. Moreover, the tuning range of FBW can be further enlarged by changing the materials of coupling layers. To verify the proposed multi-mode CRF, a triple-mode n77 band filter with center frequency of 3.723 GHz and FBW of 24.2%, and a penta-mode filter with a larger FBW up to 33% are designed and simulated. Simulation results of the original Mason model, the simplified Mason model, and the three-dimensional (3D) model based on the finite element method are consistent well with each other.

Designand development of a rapid, high voltage capacitor charging power supply based on third order resonant converter topology.

A rapid, high voltage capacitor charging power supply (CCPS) based on a third order resonant converter topology has been proposed, analyzed, and simulated using the PSpice software, and as a proof of concept, a prototype of the 6.0kV, 6.0A CCPS is also developed. High charging power, low resonant current, and high pulse repetition rate were targeted in the design. In this paper, ac analysis for the calculation of impedance and resonant frequency, and frequency dependence on current gain, and the steady state analysis of the proposed scheme have been studied and presented. The performance is analyzed by simulating the circuit for two values of load capacitances. The simulation and prototype results show linear charging of the load for both values of load capacitances. The charging times of 1.47 and 0.97ms have been achieved for load capacitances of 1.5 and 1.0 µF, respectively. The performance of the LLC topology has been compared with a conventionally used series resonant scheme. A high charging power of 18.4 kJ/s has been achieved. The topology shows a faster charging rate by ∼36% in comparison with the series LC resonant topology. The results of the analysis match with the simulation and prototype results, which confirms that the proposed scheme is suitable for rapid and reliable CCPS applications.

Improved Sensitivity of Ultrasound-Based Subharmonic Aided Pressure Estimation Using Monodisperse Microbubbles.

Subharmonic aided pressure estimation (SHAPE) has been shown effective for noninvasively measuring hydrostatic fluid pressures in a variety of clinical applications. The objective of this study was to explore potential improvements in SHAPE sensitivity using monodisperse microbubbles. Populations of monodisperse microbubbles were created using a commercially available microfluidics device (Solstice Pharmaceuticals). Size distributions were assessed using a Coulter Counter and stability of the distribution following fabrication was evaluated over 24 hours. Attenuation of the microbubble populations from 1 to 10 MHz was then quantified using single element transducers to identify each formulation's resonance frequency. Frequency spectra over increasing driving amplitudes were investigated to determine the nonlinear phases of subharmonic signal generation. SHAPE sensitivity was evaluated in a hydrostatic pressure-controlled water bath using a Logiq E10 scanner (GE Healthcare). Monodisperse lipid microbubble suspensions ranging from 2.4 to 5.3 μm in diameter were successfully created and they showed no discernable change in size distribution over 24 hours following activation. Calculated resonance frequencies ranged from 2.1 to 6.3 MHz and showed excellent correlation with microbubble diameter (R2 > 0.99). When investigating microbubble frequency response, subharmonic signal occurrence was shown to begin at 150 kPa peak negative pressure, grow up to 225 kPa, and saturate at approximately 250 kPa. Using the Logiq E10, monodisperse bubbles demonstrated a SHAPE sensitivity of -0.17 dB/mmHg, which was nearly twice the sensitivity of the commercial polydisperse microbubble currently being used in clinical trials. Monodisperse microbubbles have the potential to greatly improve the sensitivity of SHAPE for the noninvasive measurement of hydrostatic pressures.

การสร้างและทดสอบเครื่องส่งกำลังไฟฟ้าแบบไร้สาย

The purpose of the article is to study factors that affected and developed the wireless power transfer system. The system consists of a high-frequency generator and a half-bridge converter. The experiment used the calculated resonance frequency is 49.2kHz. The loads use LED bulbs, LED 12V/12W, and LED 12V/4W. The experiment results, the voltage and current of LED 12V/12W illuminated are 7.08V, and 10mA at 19cm. The LED 12V/4W illuminated are 7.40V and 10mA at 20cm. The wireless power transmitter's performance depends on the pitch between the transmitter and receiver coil, where the frequency range that provides the best electric efficiency is the resonant frequency range.

Challenges of Using Resonance Frequency Analysis to Identify Stability of a Dental Implant Placed in the Mandible.

This numerical study examined the efficacy and challenges of using resonance frequency analysis to identify the stability of implants placed in mandibles. The study also examined the feasibility of using angular stiffness as an alternative index to quantify dental implant stability in mandibles. A finite element model consisting of a mandible, an implant, an abutment, and a bonding layer (between the implant and the mandible) was created in commercially available software ANSYS. The level of osseointegration was modeled by varying the stiffness of the bonding layer. Three sets of boundary conditions were imposed on the mandible: fixed, rotationally free, and rotationally restrained. Three implant locations were studied: central, premolar, and molar positions. An alternative abutment mimicking SmartPeg and eight different implant lengths were also included. A modal analysis and a static analysis were conducted to calculate resonance frequencies and angular stiffness, respectively. Two types of vibration modes were found. One was jawbone modes, for which the mandible deformed significantly but not the bonding layer. Resonance frequencies of the jawbone modes were not sensitive to the level of osseointegration. The other was implant modes, for which the bonding layer deformed significantly but not the mandible. Among multiple implant modes obtained, only one was trackable as the level of osseointegration increased. The resonance frequency of the trackable implant mode was very sensitive to the implant location as well as boundary conditions, but not as much to the level of osseointegration. In contrast, angular stiffness was sensitive to the level of osseointegration but not as much to boundary conditions. The efficacy of using resonance frequency analysis to quantify the stability of a dental implant is questionable. Its high sensitivity to implant locations and boundary conditions as well as its low sensitivity to the level of osseointegration cause huge uncertainties in correlating measured resonance frequencies to implant stability. Angular stiffness is a much more reliable indicator because of its high sensitivity to the level of osseointegration and low sensitivity to boundary conditions.

Resonance Scattering of GHz Plane Electromagnetic Waves from Ring Dielectric Linear Structures

Resonance backscattering at the fundamental magnetic mode and the wave properties of linear structures consisting of subwave dielectric elements in the form of planar thin rings excited by the displacement currents of an incident microwave-range plane electromagnetic wave have been investigated. It is shown that the magnetic field at the main resonance frequency for a single ring is concentrated inside the ring and in the near-field zone, whereas for structures consisting of two or more rings the magnetic field is also registered in the far-field zone. The main magnetic resonances measured in the spectrum of electromagnetic fields for one and two planar rings coincide with the calculated resonance frequencies.

RESEARCH TO IMPROVE POWERTRAIN NOISE, VIBRATION AND HARSHNESS CHARACTERISTICS

The paper presents a research algorithm consisting of: a developed methodology for selection of target values for natural frequencies and localization of vibration-loaded area of the powertrain based on calculation (simulation) and experimental research of resonant frequencies of the powertrain in operating modes and disturbances from two types of roads, calculation and experimental methodology for research of natural frequencies and oscillation modes of the powertrain, developed methodology for powertrain design refinement in terms of natural frequencies up to compliance with the target values and reduction of structural noise. Results of calculation and experimental research of resonant frequencies of the powertrain in operating modes and in case of disturbance from two types of roads are provided. There is also a justification given for selection of the target value for the powertrain natural frequency. Calculation of powertrain natural frequencies and oscillation modes was performed using the finite element method; experimental verification of the calculation was carried out as well. Using the verified calculation (simulation) model, design changes were introduced to reach the target values for natural frequencies and to reduce structural noise. Comparative calculation studies of the frequency response confirming the efficiency of the design changes are carried out.

A Scaled Effective Medium Theory for Calculation of Resonant and Relaxation Frequency in Magnetic Composites

Scaled Effective Medium Theory (ScEMT) is applied to predict magnetic resonant and relaxation frequency in polymer-magnetic particle composites with favorable comparison to measured data. A single scaling function is identified that uses magnetic particulate resonant and relaxation frequencies, or magnetization and anisotropy field, volume fraction and DC susceptibility as predicted by ScEMT. Previous publications demonstrated that ScEMT improved the prediction of DC susceptibility as compared to classical models. Maxwell-Garnett (MGT) and Coherent Model Approximation (CMA) serve as theoretical baselines for comparison. However, both require separate scaling functions in their prediction of resonant and relaxation. Measured data are presented that suggest a single scaling function of ScEMT is sufficient to calculate both parameters. The paper emphasizes the application of the models and shows a wide range of particulate chemistries. ScEMT calculates susceptibility, resonant and relaxation frequency that agree with measurement. The paper concludes by predicting dispersive permeability that represents improvement over both CMA and MGT models. Future studies will address formulation of an EMT model (s) that describe mixtures of hard and soft magnetic materials mixed in a polymer composite. EMT for composite dielectric properties will be expanded to address the chaining. Early results of that effort will be reported in a separate paper.

Results from the Alfvén Eigenmode Active Diagnostic during the 2019-2020 JET deuterium campaign

This paper presents results of extensive analysis of mode excitation observed during the operation of the Alfvén Eigenmode Active Diagnostic (AEAD) in the JET tokamak during the 2019-2020 deuterium campaign. Six of eight toroidally spaced antennas, each with independent power and phasing, were successful in actively exciting stable MHD modes in 479 plasmas. In total, magnetic resonances were detected with up to fourteen fast magnetic probes. In this work, we present the calculations of resonant frequencies f 0, damping rates γ < 0, and toroidal mode numbers n, spanning the parameter ranges f 0≈ 30–250 kHz, −γ ≈ 0–13 kHz, and . In general, good agreement is seen between the resonant and the calculated toroidal Alfvén Eigenmode frequencies, and between the toroidal mode numbers applied by the AEAD and estimated of the excited resonances. We note several trends in the database: the probability of resonance detection decreases with plasma current and external heating power; the normalized damping rate increases with edge safety factor but decreases with external heating. These results provide key information to prepare future experimental campaigns and to better understand the physics of excitation and damping of Alfvén Eigenmodes in the presence of alpha particles during the upcoming DT campaign, thereby extrapolating with confidence to future tokamaks.

Synthetic jet actuator with two opposite diaphragms

Abstract The synthetic jet actuators are one of the most investigated types of actuators used in heat transfer and active flow control. The energetic efficiency of actuators is a key parameter determining the possibility of device use. The actuators with two or more diaphragms have higher efficiency than the actuators with only one. The paper presents the investigations of the acoustic synthetic jet actuator with two opposite diaphragms. In the paper, synthetic jet velocity, Reynolds number and the energetic efficiency as a function of oscillating actuator frequency, for a different cavity, orifice configuration and one real input power P 0 = 2 W were studied. The possibility of theoretical calculation of first and second resonance frequency were checked. The coupling ratio for actuators was calculated. The maximum energetic efficiency was η = 8.67% and Reynolds number Re = 8503. The possibility of using the same dependencies and rules during the design of actuators with two opposite diaphragms as in the case of actuators with one diaphragm was demonstrated. The results may be useful in the design of the actuators of the two membranes.