Resonance Region Research Articles

Nonlinear response of magnetization obeying inertial dynamics to superimposed dc and ac fields and dynamic magnetic hysteresis

The nonlinear ac stationary responses of magnetization and the dynamic magnetic hysteresis of ferromagnetic particles with uniaxial anisotropy acted on by both external dc and ac magnetic fields are evaluated by employing the inertial Landau–Lifshitz–Gilbert equation. Analytical expressions are obtained for the components of the second- and third-order nonlinear susceptibility tensors using the perturbation method. The dynamic nonlinear susceptibility strongly depends on the dc field strength. The effect of inertia on the area and slope of the dynamic magnetic hysteresis loop is demonstrated. In addition to nutation resonance, the main nonlinear effects previously observed in the ferromagnetic resonance region (frequency doubling and appearance of weak subharmonic resonance peaks) are predicted in the nutation resonance frequency region.

Parametric Vibration and Combined Resonance of a Bending-Torsional Coupled Turbine Blade With a Preset Angle

Abstract The parametric vibration and combined resonance of a turbine blade with a preset angle subjected to the combined effect of parametric and forced excitation were investigated. The blade was modeled as a rotating beam considering the effects of centrifugal, gyroscopic, and bending-torsion coupling. The instability region of the corresponding linear system with parametric excitation was analyzed using Floquet theory, and the effect of blade parameters on this region was discussed. Notably, the parametric vibration of the torsional degree-of-freedom (DOF) caused by parametric excitation of the bending degree-of-freedom has been found. The results show that the size and position of the parameter resonance region are affected by the blade aspect ratio and preset angle, respectively. Furthermore, the multiscale method was employed to solve the blade equation under the combined action of parametric and forced excitation to study the combined resonance caused by forced excitation and gyroscopic items. The effect of blade parameters and excitation characteristics on regions of combined resonance were investigated. The phenomenon of heteroclinic bifurcation was observed due to changes in the excitation frequency, and the harmonic components that accompanied the bifurcation changed. Specifically, a multiperiod response dominated by the excitation frequency and subharmonic components shifted to a single-period response dominated by subharmonic components. This study provides a theoretical explanation for the nonsynchronous resonance of blades and the subharmonic signals in blade vibration and guides blade parameter design, especially for wind turbines.

Time-delay feedback control of a suspended cable driven by subharmonic and superharmonic resonance

The longitudinal time-delay feedback control strategy is implemented to suppress the subharmonic and superharmonic responses of the suspended cable. Formulated based on the Hamilton variational principle and the longitudinal time-delay feedback strategy, the in-plane nonlinear differential equations for a suspended cable are formulated, and Galerkin method is utilized to transform the equations into delayed differential equations. By using the method of multiple scales, approximate solutions for the 1/2-subharmonic and second-order superharmonic resonance responses of the controlled suspended cable were derived. The effects of the time delay and control gain are obtained through numerical examples. The research results demonstrate that through the adjustment of control gain and time delay, resonance regions can be avoided, effectively suppressing large-amplitude vibrations in the suspended cable, thereby achieving favorable control performance.

Resource utilization of stone waste and loess to prepare grouting materials

Loess, a terrestrial clastic sediment, is formed essentially by the accumulation of wind-blown dust, while stone waste (SW) is an industrial waste produced during stone machining. Utilising loess and SW to prepare environmentally-friendly supplementary cementitious materials can not only address environmental issues caused by solid waste landfills but also meet the demand of reinforcement of coal-seam floor aquifer for grouting materials. In this paper, the effects of the loess/SW mass ratio and calcination temperature on the transformation of calcined products are investigated and their pozzolanic activities are evaluated. The workability, environmental impact and cost of grouting materials based on cement and calcined products are also assessed. Experimental results reveal that higher temperatures favour the formation of free lime and periclase, which tend to be involved in solid-state reactions. Higher temperature and loess/SW mass ratio strengthens the diffraction peaks of dodecalcium hepta-aluminate (C12A7), dicalcium ferrite (C2F) and dicalcium silicate (C2S). The clay minerals in loess become completely dehydroxylated before 825 °C, generating amorphous SiO2 and Al2O3. Covalent Si–O bonds are interrupted and that disordered silicate networks are generated in the calcined products, which is confirmed by the increased strength of the Si29 resonance region at −60 ppm to −80 ppm. Although co-calcined loess and SW contain the most four-fold aluminium at 950 °C, recrystallisation depresses the pozzolanic activity. Hence, the loess/SW sample designated LS2-825 exhibits the better hydration activity. Additionally, grouting materials composed of cement and LS2-825 exhibit good setting times, fluidity, strength and a low carbon footprint in practical engineering applications, and they also provide the additional benefit of being cost effective.

Experimental investigation on L-beam vortex-induced vibration piezoelectric energy harvester with interference step

In this study, an L-beam vortex-induced vibration piezoelectric energy harvester with interference step is proposed. The experimental results show that the interference step can broaden the effective wind speed bandwidth in the second resonance region of the energy harvester and increase its energy output amplitude significantly. When the load resistance is 90 kΩ, the effective wind speed bandwidth in the second resonance region of the energy harvester can be expanded by a maximum of more than 200%, and the peak output power can be increased by a maximum of 291% by adjusting the position, width and height of the step.

3D Size-Dependent Dynamic Instability Analysis of FG Cylindrical Microshells Subjected to Combinations of Periodic Axial Compression and External Pressure Using a Hermitian C2 Finite Layer Method Based on the Consistent Couple Stress Theory.

This work develops a three-dimensional (3D) weak formulation, based on the consistent couple stress theory (CCST), for analyzing the size-dependent dynamic instability behavior of simply-supported, functionally graded (FG) cylindrical microshells that are subjected to combinations of periodic axial compression and external pressure. In our formulation, the microshells are artificially divided into nl layers. The displacement components of each individual layer are selected as the primary variables, which are expanded as a double Fourier series in the in-plane domain and are interpolated with Hermitian C2 polynomials in the thickness direction. Incorporating the layer-wise displacement models into our weak formulation, we develop a Hermitian C2 finite layer method (FLM) for addressing the current issue. The accuracy and the convergence rate of our Hermitian C2 FLM are validated by comparing the solutions it produces with the accurate two-dimensional solutions of critical loads and critical pressures of FG cylindrical macroshells and single-walled carbon nanotubes, which were reported in the literature. The numerical results show the effects of the material length-scale parameter, the inhomogeneity index, the radius-to-thickness and length-to-radius ratios, the load magnitude ratio, and the static and dynamic load factors on the first principal and first secondary instability regions of parametric resonance of simply-supported FG cylindrical microshells are significant.

Rice husk silica blended fillers for engine mount application

The functional properties of engine mounts largely depend on the rubber compound formulation. This study proposes the use of rice husk–derived silica (RHS) blended with carbon black (N772) as an effective and environmentally friendly substitute for fillers used in rubber engine mounts (REMs). CV-60 natural rubber was filled with the blended fillers at various ratios, and their compatibility for use as rubber engine mounts (REMs) was assessed. Grey Relational Analysis was utilised to determine the optimal blend loading levels for use in rubber engine mounts, resulting in 40 phr of N772 and 20 phr of RHS cured at 130 °C and 2.5 MPa for 20 min. The developed REMs and conventional REMs had low vibration data variation during the performance assessment. Their resonance transmissibility was 5.03 and 3.74, corresponding to natural frequencies of 24.27 Hz and 26.94 Hz, respectively. The RHS/N772 REMs had excellent damping characteristics and lower transmissibility in the isolation zone of the vibration isolation curve, which is outside of the resonant frequency region. The efficiency curves showed that the blended fillers are a better and more effective material for REMs at all frequencies, balancing static deflection and vibration isolation.

Primary resonance characteristics of a cylindrical bubble based on the multi-scale method

This paper describes a primary resonance theoretical model for a cylindrical bubble under acoustic excitation. Based on the multi-scale method, an analytical solution of the bubble–wall equation with second-order accuracy is obtained and numerically verified. The oscillation characteristics in the time domain and the frequency response characteristics of the oscillations under primary resonance are analyzed with different amplitudes and frequencies of acoustic excitation and the equilibrium radius of the bubble. This study yields the following primary findings: (1) For the cylindrical bubbles, the primary resonance of the bubble exists in unstable regions. Nonlinear behaviors such as jumps, hysteresis, and multivalued solutions may be widely present. (2) As the amplitude of the acoustic excitation and the bubble equilibrium radius increase, the backbone of the amplitude–frequency response curve bends to the left and the unstable region gradually expands. (3) When the dimensionless amplitude of the acoustic excitation is less than 0.005 and the bubble equilibrium radius is less than 1.0 × 10−5 m, the unstable region of resonance disappears.

Electron cyclotron resonance (ECR) enhanced diverging magnetic field for controlled particle flux in a microwave-excited plasma column – a numerical investigation

The present work is an investigation of the effect of an externally applied diverging magnetic field on a surface microwave-sustained plasma column. Microwaves (2.45 GHz) are allowed to propagate through a tapered waveguide system containing a discharge tube made up of quartz. Argon gas flows down the tube from top to bottom maintaining a pressure of 1 Torr and a plasma is ignited within the tube owing to the surface microwave propagation. In the absence of a magnetic field, the plasma column exhibits discrete regions of overdense plasma near its center where the electric field of the incident microwaves is observed to be high. As the gas flows down the tube, the plasma density is also found to decrease and the resulting plasma profile is asymmetric about its length. However, in the presence of an axially applied diverging magnetic field , an axial force acts on the plasma, and the discrete overdense plasma regions are found to get symmetrically arranged along the plasma axis. Interesting results are observed when the diverging magnetic field includes a region of electron cyclotron resonance (ECR) corresponding to the microwave frequency. In the presence of an ECR, the electrons are expected to experience resonant heating by microwaves other than the direct heating by these waves. Under such conditions, the discharge dynamics are governed by the resonance mechanism, and the bright spots of overdense plasma regions get shifted to the ECR positions. As the magnetic field strength increases, the overdense plasma moves axially away from the center. These results are a clear indication of a magnetically controlled particle flux over a target and can be exploited in various material processing applications, particularly for surface cleaning applications in the semiconductor industries.

Perfect adjustable absorber based on Dirac semi-metal high sensitivity four-band high frequency detection

In this paper, we propose a highly sensitive, four-band, high-frequency detector with a perfectly tunable absorber based on Dirac semimetals. The design architecture relies on a simple rectangular shape, with absorption rates approaching 100 % at f1 = 9.644 THz, f2 = 9.964 THz, f3 = 11.12 THz, and f4 = 12.432 THz. The symmetric structure exhibits polarization incoherence. Impedance calculations through parameter inversion confirm the occurrence of perfect absorption in the resonance region. By adjusting key parameters of the absorber and modifying the Fermi level of BDS, we demonstrate the absorber's excellent tunability and manufacturing tolerance. Lastly, exploring its sensitivity by altering the external refractive index reveals a maximum refractive index sensitivity of 560 GHz/RIU. Under changing refractive index conditions, the overall absorption rate of the absorber remains above 0.94. In light of these findings, the absorber holds significant reference value in the fields of communication, sensing, and optoelectronic devices.

Comparison and evaluation of resolved resonance region covariance representations

ABSTRACT The covariance matrices for the evaluated resolved resonance region parameters are typically processed into a grouped covariance representation for use in uncertainty propagation studies. An alternative method for performing uncertainty propagation would be to use the resonance parameters covariance matrix to sample many realizations of resonance parameters, and then perform a simulation with each sample, employing the total Monte Carlo method. In this paper, we demonstrate that these two techniques can yield drastically different estimations of the uncertainty on k eff . Furthermore, we provide reasoning as to why the grouped covariance approximation is a nonphysical approximation for the resolved resonance region, and how sampling resonance parameters is able to capture variations in the structure of the point-wise cross sections. Our recommendation is that the community move away from the grouped covariance approximation and towards a continuous energy representation, which could be generated by sampling resonance parameters, and ensure that the resonance parameter covariance matrices in evaluated libraries yield realistic grouped cross section uncertainties, regardless of group structure.

Measurements of keV-Neutron capture cross sections and capture gamma-ray spectra of 74,76,78,80,82Se

ABSTRACT The neutron capture cross sections and capture γ -ray spectra of 74,76,78,80,82Se were measured in a region from 15 to 100 keV and around 550 keV. A neutron time-of-flight method was used with a ns-pulsed neutron source based on the 7Li(p,n)7Be reaction and a large anti-Compton NaI(Tl) γ -ray spectrometer. A pulse-height weighting technique was applied to the observed γ -ray pulse-height spectra to obtain capture yields. The capture cross sections of 74,76,78,80Se were derived with uncertainties from 4.0 to 5.5% and those of 82Se were derived with uncertainties of 6.5–27% by using the standard capture cross sections of 197Au. The present results of 78,82Se were the first experimental ones above the resolved resonance region. The present results were compared with previous measurements and the evaluated values in JENDL-5.0 and ENDF/B-VIII.0. The evaluations of JENDL-5.0 differ from the present results of 74,76,78,80Se and 82Se by 0.9–51% and 6.9–120%, respectively. The capture γ -ray spectra of 74,76,78,80,82Se were derived by unfolding the observed capture γ -ray pulse-height spectra. The present results were the first experimental ones in the keV region.

Colossal Kerr nonlinearity without absorption in a five-level atomic medium

In this work, we present an analytical method to achieve giant Kerr nonlinearity without absorption in a five-level atomic medium. By using iterative perturbation technique on density matrix equations, we have derived the analytical expressions of nonlinear susceptibility and Kerr nonlinear coefficient in the presence of spontaneously generated coherence (SGC) and relative phase between applied laser fields. It shows that, this five-level atomic medium exhibits multiple electromagnetically induced transparency (EIT) at three different frequencies, at the same time, the Kerr nonlinear coefficient is enhanced around three transparent spectral regions; in each such EIT region appears a pair of positive–negative peaks of Kerr nonlinear coefficient. In particular, these nonlinear peaks are moved to the center of the EIT windows via SGC. This means that the Kerr nonlinear coefficient is enhanced with completely suppressed absorption at different transparency frequencies. Furthermore, the magnitude and the sign of the Kerr nonlinear coefficient are easily controlled according to the SGC strength, the coupling laser intensity, and the relative phase between applied laser fields. Such a giant nonlinear medium can be useful for photonic devices working in the resonant frequency region without absorption. As a typical application, this giant Kerr nonlinear material has been applied to an interferometer for the formation of optical bistability, and showed the appearance of OB at the resonant frequency with significantly reduced threshold intensity and OB width.

Magneto-thermoelastic coupled resonance characteristics of a rotating functionally graded ferromagnetic cylindrical shell under double harmonic line loads

The magneto-thermoelastic coupled resonance of a rotating functionally graded (FG) ferromagnetic cylindrical shell subjected to double harmonic line loads in magnetic and temperature fields is investigated. In accordance with Donnell's thin shell theory on the physical neutral surface, the nonlinear geometric equations are determined. Utilizing the thermoelastic constitutive relationships, combining with the gradient characteristics and temperature dependence of physical parameters, the governing equations of kinetic energy and strain energy are given. Based on the magnetoelasticity theory, and considering the nonlinear magnetization of ferromagnetic metal, the calculation formulas of Lorentz force and magnetizing force acting on the shell are deduced. The magneto-thermoelastic coupled dynamic equations are derived by applying Hamilton principle and discretized by Galerkin method. Subsequently, considering the different resonance forms, the multiple scales method and Lyapunov stability theory are employed to obtain the theoretical solutions and stability discriminants. Numerical examples are carried out to plot the characteristic diagrams with different parameters, which are used to analyze the characteristics of nonlinear coupled resonance. Furthermore, the primary resonance and combination resonance are selected to analyze the bifurcation and chaotic behavior. Results show that the variation of different parameters affects obviously the resonance amplitude and stability. The changes of amplitude and position of hard excitation can lead to resonance region drift. Amplitude, frequency, and position of excitation have significant effects on bifurcation and chaos. The motion state of cylindrical shell is transmitted from periodic response to chaotic response through the accumulation of period-doubling bifurcation.

The Vibration Isolation Properties of an Asymmetrical Quasi-Zero Stiffness Isolator with Geometrical Nonlinear Damping

This paper proposes a Quasi-Zero-Stiffness (QZS) vibration isolator with asymmetric stiffness and geometric nonlinear damping. The nonlinear stiffness and nonlinear damping characteristics of proposed model are studied. The motion equation of proposed system under force excitation is established, and its dynamic response is solved by the Harmonic Balance Method (HBM). In addition, the influence of nonlinear damping on force transmissibility is studied. The results indicate that the proposed isolator has a large equivalent damping ratio in the resonance region and a small equivalent damping ratio in the high-frequency region. Therefore, the proposed asymmetrical QZS isolator with nonlinear damping can supress the resonance in lowfrequency under force excitation and achieve a good highfrequency vibration isolation effect simultaneously than that with linear damping.

Effects of multi motion responses and incident-wave height on the gap resonances in a moonpool

The hydrodynamic characteristics of a free-floating moonpool encountering the gap resonances are investigated based on the constrained interpolation profile method in numerical wave tank. This paper mainly concentrates on the influences of the moonpool's motion responses and the incident-wave height on the gap resonances in the free-floating moonpool. Numerical results demonstrated that the heave response significantly changes the frequency and the magnitude of the linear gap resonance, while the roll motion influences more on the vertical wave loads and the wave responses in the fluid field. The heave and roll response of the free-floating moonpool are generally independent. Moreover, the magnitudes of the nonlinear gap resonances have the tendency of catching up and exceeding the linear gap resonance as the incident-wave height increasing for the free-floating moonpool, which is the consequence of the higher-order harmonics driven by the nonlinear processes and the linear secondary resonant region induced by the heave response. Based on the wavelet transform, it could be observed that the amplified harmonic component usually takes more time to be fully developed than other harmonic components during the development of its corresponding nonlinear gap resonance.

Устойчивость трансляционных колебаний зажатой капли маловязкой жидкости

The study investigates oscillatory dynamics of a drop of a low-viscosity liquid surrounded by another liquid under translational low-amplitude vibration influence. A drop of equilibrium cylindrical shape is sandwiched between parallel solid planes. The contact angles are straight and constant, the contact lines of the three media slide freely along the surface of the plates. At the droplet–surrounding liquid interface, a thin viscous boundary layer is taken into account. Natural and forced oscillations of the drop are considered. In the main order of expansion in terms of small amplitude of vibrations, the natural frequencies of oscillations of an inviscid cylindrical drop were obtained. In the first order of expansion, a correction to the frequency was found, caused by energy dissipation in the viscous boundary layer. The stability of forced oscillations with respect to small disturbances was studied. Parametric resonance occurred when the synchronism condition was met: the vibration frequency was equal to the sum of the frequencies of two adjacent modes of natural oscillations. An expression describing the resonant regions was found. It is shown that low viscosity leads to the appearance of a vibration amplitude threshold and a shift in the instability region when compared with zero viscosity.

A Compact Model for Unresolved Resonance Region Cross Sections

For decades, the probability table technique has been used to model the behavior of neutron cross sections in the unresolved resonance region with a stochastic approach. Early work from Hwang hinted at the possibility of a universal probability distribution to fit the URR cross section distribution. In this work we present a solution to Hwang’s problem: the normal inverse Gaussian distribution fits the probabilistic behavior of the total cross section almost perfectly for the most important nuclides, both in asymptotic behavior and around the more probable regions.

Partial Wave Amplitude Analysis in Pion-Induced Reactions at the HADES Experiment

The High Acceptance Di-Electron Spectrometer (HADES) collaboration at GSI employs a pion beam to examine the characteristics of baryonic resonances and their decay channels. This pion-beam facility enables the generation of baryonic resonances at a fixed center of mass energy (√s), i.e. in the S-channel. In anticipation of conducting a more comprehensive exploration of the resonance regions in pion-proton collisions, a new implementation of the K-matrix & D-matrix frameworks is currently under development. This updated implementation aims to offer a refined mapping of these regions. Example fits are presented showing the current status and the potential of the new framework.

Investigation of Uncertainty Propagation in the Resolved Resonance Range

This paper presents a comparative study using the first-order formula (also called “sandwich”) and the multivariate sampling methodologies for propagating uncertainty in the resolved resonance region. A distinctive aspect of this work is the generation of random cross sections by sampling Resonance Parameters (RPs) taking in consideration their correlations provided in nuclear data libraries via the Resonance Parameter Covariance Matrix (RPCM). SCOOBY (Sampling COvariance OBservatorY), a newly developed sampling tool, is presented in this paper. This tool relies on the GAIA-2 nuclear data processing code to read and correct the RPCM and generate random cross sections. The study compares the sandwich method that relies on sensitivity coefficients and covariance matrices, with the sampling method, which involves numerous Monte Carlo simulations with random cross sections. The comparison is tested on an ICSBEP benchmark, PU-MET-MIXED-002, chosen for its sensitivity to 239Pu cross sections. The results indicate that both methods quantify similar uncertainties, confirming the reliability of both the SCOOBY module and the GAIA-2 code. By using the PU-MET-MIXED-002 benchmark and sampling 239Pu resonance parameters, this work demonstrates the effectiveness of these methodologies in estimating uncertainty in criticality safety calculations. The findings highlight the robustness of these approaches in uncertainty propagation, suggesting the need for further research on additional benchmarks and expanded uncertainty propagation studies.