Resonance Condition Research Articles

Magnetic field enhanced terahertz emission from metallic nanostructures with response to laser spatial profile distribution

This communication proposes an analytical model that exhibits terahertz (THz) radiation generation from spatially corrugated noble-metal spherical and cylindrical nanoparticles (NPs) placed under the influence of an externally applied static magnetic field. This scheme involves the resonant excitation of THz radiation through the beat-wave of two lasers in the presence of ponderomotive nonlinearities. Effect of magnetic field as well as laser intensity profiles, which include super, cosh, flat-top and ring-shaped Gaussian profiles, have been investigated. The incorporation of the magnetic field induces substantially more dynamic laser-metal coupling and influences the surface plasmon resonance condition associated with electrons of the NPs, thereby leading to stronger THz emission. Our results also demonstrate that the spatial profile of the laser affects the THz output, as it impacts the excitation and dynamics of the NPs. Additionally, we find that both the shape, size and interparticle-separation of NPs play crucial roles in enhancing THz generation. Furthermore, we explore the effects of varying other parameters like electric field strength and beam waist of incident lasers. These findings provide valuable insights for the design and optimization of THz sources based on NP systems, offering new avenues for applications in spectroscopy, imaging, communication and biomedical sciences.

Digital twin-driven senseless cutting force monitoring and vibration stability control of a rotary ultrasonic machining system

Rotary ultrasonic machining (RUM) emerges as a superior technique for processing difficult-to-cut materials due to its capacity to improve machining efficiency and surface quality. The tool vibration amplitude and its stability in the machining process are critical to guarantee the performance of RUM. However, due to the lack of a reliable status monitoring and control method, the operator cannot identify and solve the problem of vibration loss in time, greatly restricting the wider industrial application of RUM. This study proposes a digital twin-driven method to monitor and control the status of the RUM system. A twin model of the RUM system is first established, which describes the relationship among the driving electrical variables, the vibration amplitude, and the external load when the system works at the resonant state. A frequency tracking algorithm using the electrical signals is used to make the RUM work at the resonant state, which ensures the twin model is always aligned with the physical RUM system. And the actual vibration amplitude and the external load can be derived in real time. Then, a voltage-adjusting method is proposed to make the actual vibration amplitude approach its idle value and the cutting force is updated. Applying the above route, the cutting force and vibration amplitude can be in-process monitored without extra sensors, and vibration stability can be improved. Finally, loading and drilling experiments are carried out to verify the efficacy of the proposed digital twin-driven method. The experimental results demonstrate that the proposed method can monitor the cutting force accurately (average deviation during the whole drilling process <10 %) without using any additional force sensor like dynamometer, and ensure the stability of vibration amplitudes under load (amplitude variation <10 %), enabling the RUM system to become intelligent.

High-fidelity transfer of helical phase via hyper-Raman scattering in a monolayer graphene

Graphene is a fascinating two-dimensional optical material with a unique electronic band structure and a giant optical nonlinearity under the action of a strong magnetic field. Here we propose a scheme to transfer helical phase of the orbital angular momentum (OAM) light via hyper-Raman scattering in a monolayer graphene assisted by a magnetic field. Due to the unique electronic properties and selection rules near the Dirac point, it is found that high-fidelity transfer of phase structure and, in particular, of OAM from a pump field to the Raman field generated in a hyper-Raman scattering process occurs under the resonance condition. Interestingly, the obtained results allow us to control the intensity of Raman field with stable phase structure by varying the intensities of two pump fields. Hereby, the mechanism of efficient generation and manipulation of OAM Raman field may have exciting potential applications in the generation of short-wavelength coherent radiation, conversion of frequency as well as nonlinear spectroscopy in graphene materials.

Study of resonance conditions on higher harmonics in an electrical network supplying a nonlinear load

Study of resonance conditions on higher harmonics in an electrical network supplying a nonlinear load

Highly squeezed states in ring resonators: Beyond the undepleted-pump approximation

Highly squeezed states in ring resonators: Beyond the undepleted-pump approximation

Flexural Rigidity Influence on Dynamic Response of Orthoropic Rectangular Plate Resting on Constant Elastic Foundation

This research article considers the flexural rigidity influence along both x and y axes on the dynamic response of orthotropic rectangular plate resting on constant elastic foundation with elastic end conditions. The orthotropic rectangular plate model is a coupled fourth order partial differential equation having variables and singular coefficients. The solutions to this model are arrived at by reconstructing the fourth order partial differential. This partial differential equation model is converted to a set of coupled second order ordinary differential equations by using a special technique adopted by Shadnam et al., [11]. This set of second order ordinary differential equations is then reduced using modified asymptotic method of Struble. The closed form solution is evaluated, resonance conditions are obtained and the results are showed in plotted curves to depict the influence of flexural rigidities along both x and y axes on the dynamic response of orthotropic rectangular plate resting on constant elastic foundation with elastic end conditions for both cases of moving distributed mass and moving distributed force.

Amplitude Variations of Moving Distributed Masses of Orthotropic Rectangular Plate with Elastically Supported Ends under Moving Loads

The deflection of thin orthotropic rectangular plate under moving loads is a classic problem in solid mechanics. However, the equations are challenging to solve due to their non linearity and complexity. At the same time, this equation is a coupled fourth order partial differential equation having variables and singular coefficients. In this research article, the partial differential equation is converted to a set of coupled second order ordinary differential equations by using a special technique adopted by Shadnam et al., [19]. This transformed set of second order ordinary differential equations is then reduced using modified asymptotic method of Struble and Laplce transformation. The closed form solution is evaluated, resonance conditions are obtained and the results are showed in plotted curves to solve the variations in amplitudes for some varying orthotropic plate parameters with elastically supported ends under moving loads for both cases of moving distributed force and moving distributed mass.

Collision dynamics between breather and lump-type localized waves in the (3+1)-dimensional shallow water wave equation

In this paper, the collision dynamics of breather and lump-type localized waves in the (3+1)-dimensional shallow water wave equation are investigated in detail. Firstly, the auto-Bäcklund transformation and the linear representation of the (3+1)-dimensional shallow water wave equation are derived in virtue of the truncated Painlevé expansion method, which provide convenience in solving the (3+1)-dimensional shallow water wave equation. Secondly, based on the linear representation and the principle of linear superposition, the rational solutions in the exponential and polynomial forms are constructed. Tuning the free parameters of the rational solutions, localized waves of various patterns are obtained such as breather, lump-type localized waves and their hybrid structure. The anomalous inelastic interaction phenomenons of breather and lump-type localized waves are exhibited. Thirdly, combining the large-time behaviors of solution with the velocity relationship of localized waves, the dynamical properties and the classification of localized wave solutions are discussed in detail. Finally, we discuss the bound state of breather and lump-type localized waves under the velocity resonance condition, three different types of lump-breather molecules are displayed. The obtained results further enrich the structures and dynamical behaviors of localized waves. It is expected that the interaction phenomena taking place in the (3+1)-dimensional shallow water wave equation will be helpful in predicting or controlling some related shallow water wave phenomena.

Analysis of three-body decays B→D(V→)PP under the factorization-assisted topological-amplitude approach

Motivated by the accumulated experimental results on three-body charmed B decays with resonance contributions in , LHCb, and Belle (II), we systematically analyze B(s)→D(s)(V→)P1P2 decays with V representing a vector resonance (ρ,K*,ω, or ϕ) and P1,2 as a light pseudoscalar meson (pion or kaon). The intermediate subprocesses B(s)→D(s)V are calculated with the factorization-assisted topological-amplitude (FAT) approach and the intermediate resonant states V described by the relativistic Breit-Wigner distribution successively decay to P1P2 via strong interaction. Taking all lowest resonance states (ρ,K*,ω,ϕ) into account, we calculate the branching fractions of these decay modes as well as the Breit-Wigner-tail effects for B(s)→D(s)(ρ,ω→)KK. Our results agree with the data by , LHCb, and Belle (II). Among the predictions that are still not observed, there are some branching ratios of order 10−6–10−4 which are hopeful to be measured by LHCb and Belle II. Our approach and the perturbative QCD approach (PQCD) adopt the compatible theme to deal with the resonance contributions. What is more, our data for the intermediate two-body charmed B-meson decays in FAT approach are more precise. As a result, our results for branching fractions have smaller uncertainties, especially for color-suppressed emission diagram dominated modes. Published by the American Physical Society 2024

Time-delay feedback control of nonlinear forced vibration of graphene/piezoelectric sandwich nanoplates under a mechanical shock

In this study, the nonlinear forced vibration of graphene/piezoelectric sandwich nanosheets under mechanical impact was investigated. For the first time, linear (displacement and velocity) and nonlinear (displacement) time-delay proportional derivative (PD) controllers were applied to graphene/piezoelectric sandwich nanosheets, and the primary/secondary resonance under different time-delay parameters were analyzed. An approximate analytical solution for the nonlinear forced vibration control equation was obtained using the multiple scale perturbation method, and the stability of graphene/piezoelectric sandwich nanosheets under primary/secondary resonance conditions was discussed using the Ross Herwitz theorem. Finally, the results of this study were compared with those of other studies. The feasibility of the research methodology was demonstrated. On this basis, the research results indicate that linear displacement delay, nonlinear displacement delay, and velocity delay parameters can suppress the unsteady vibration characteristics of the main system. And comparing the linear and nonlinear displacement time-delay, it is found that the nonlinear displacement time-delay has a greater effect on the system. Specifically, the presence of nonlinear displacement time-delay changes the vibration characteristics of the curve from hard spring characteristics to soft spring characteristics. Comparison of displacement time-delay and velocity time-delay reveals that velocity time-delay gives better control over the system. In addition, the results show that the excitation amplitude, nonlocal parameters, and external voltage enhance the nonlinear characteristics of the system under the main and superharmonic resonance conditions before the time-delay control. Subharmonic resonance conditions, the system parameters make the vibration range wider. After the time-delay control, the influence of these three factors on the system vibration is significantly reduced for the three resonance conditions, especially for the non-local parameters. The results of the study can provide guidance for active control of time delay in different types of nanodevices for engineering applications.

Numerical studies of one-way Lamb and SH mixing method in composite laminates with transverse-isotropic quadratic nonlinearity

Abstract The resonant behavior of one-way Lamb and SH (shear horizontal) mixing method in composite laminates with transverse-isotropic quadratic nonlinearity is investigated through numerical simulations in this paper. Different from previous studies, the composite constitutive model is combined from orthotropic elasticity and transverse-isotropic quadratic nonlinearity, which is implemented by ABAQUS/VUMAT subroutine. When two fundamental waves (S 0-mode Lamb waves and SH 0 waves) mix in composite laminates with quadratic nonlinearity, the resonant SH 0 waves can be generated with the resonance condition ω S 0 /ω SH 0 = 2 κ/(κ + 1). Meanwhile, the relationships between the acoustic nonlinear parameter (ANP) and damage degree, fundamental frequency, frequency deviation, propagation distance are also investigated. Moreover, the method of locating the damage region in composite laminates is proposed and verified by using the resonant wave time-domain signal.

Multiple harmonics suppressing methods based on generalized resonant extended state observer: methodology and analysis

Multiple harmonics suppressing methods based on generalized resonant extended state observer: methodology and analysis

Characterisation of the warm-Jupiter TOI-1130 system with CHEOPS and a photo-dynamical approach

Context. Among the thousands of exoplanets discovered to date, approximately a few hundred gas giants on short-period orbits are classified as ‘lonely’ and only a few are in a multi-planet system with a smaller companion on a close orbit. The processes that formed multi-planet systems hosting gas giants on close orbits are poorly understood, and only a few examples of this kind of system have been observed and well characterised. Aims. Within the contest of a multi-planet system hosting a gas giant on short orbits, we characterise the TOI-1130 system by measuring masses and orbital parameters. This is a two-transiting planet system with a Jupiter-like planet (c) on a 8.35 days orbit and a Neptune-like planet (b) on an inner (4.07 days) orbit. Both planets show strong anti-correlated transit timing variations (TTVs). Furthermore, radial velocity (RV) analysis showed an additional linear trend, a possible hint of a non-transiting candidate planet on a far outer orbit. Methods. Since 2019, extensive transit and radial velocity observations of the TOI-1130 have been acquired using TESS and various ground-based facilities. We present a new photo-dynamical analysis of all available transit and RV data, with the addition of new CHEOPS and ASTEP+ data, which achieve the best precision to date on the planetary radii and masses and on the timings of each transit. Results. We were able to model interior structure of planet b constraining the presence of a gaseous envelope of H/He, while it was not possible to assess the possible water content. Furthermore, we analysed the resonant state of the two transiting planets, and we found that they lie just outside the resonant region. This could be the result of the tidal evolution that the system underwent. We obtained both masses of the planets with a precision of less than 1.5%, and radii with a precision of about 1% and 3% for planet b and c, respectively.

Bondi-Hoyle-Lyttleton accretion around the rotating hairy Horndeski black hole

Modeling of the shock cone formed around a stationary, hairy Horndeski black hole with Bondi-Hoyle-Lyttleton (BHL) accretion has been conducted. We model the dynamical changes of the shock cone resulting from the interaction of matter with the Horndeski black hole, where the scalar field and spacetime have a strong interaction. The effects of the scalar hair, the black hole rotation parameter, and the impacts of the asymptotic speed have been examined, revealing the influence of these parameters on the shock cone and the trapped QPO modes within the cone. Numerical calculations have shown that the hair parameter significantly affects the formation of the shock cone. As the absolute value of the hair parameter increases, the matter in the region of the shock cone is observed to move away from the black hole horizon. The rate of matter expulsion increases as h/M changes. After h/M < -0.6, a visible change in the physical structure of the shock cone occurs, ultimately leading to the complete removal out of the shock cone. On the other hand, it has been revealed that the asymptotic speed significantly affects the formation of the shock cone. As h/M increases in the negative direction and the asymptotic speed increases, the stagnation point moves closer to the black hole horizon. When the value of the hair parameter changes, the rest-mass density of the matter inside the cone decreases, whereas the opposite is observed with the asymptotic speed. Additionally, the formed shock cone has excited QPO modes. The deformation of the cone due to the hair parameter has led to a change or complete disappearance of the QPOs. Meanwhile, at asymptotic speeds of V ∞/c < 0.4, all fundamental frequency modes are formed, while at V ∞/c = 0.4, only the azimuthal mode is excited, and 1:2:3:4:… resonance conditions occur. No QPOs have formed at V ∞/c = 0.6. The results obtained from numerical calculations have been compared with theoretical studies for M87*, and it has been observed that the possible values of h/M found in the numerical simulations are consistent with the theory. Additionally, the results have been compared with those for the GRS 1915+105 black hole, and the hair parameters corresponding to the observed frequencies have been determined.

Evaluation of highly sensitive vibration states of nanomechanical resonators in liquid using a convolutional neural network

Nanomechanical resonators can detect various small physical quantities with high sensitivity using changes in resonant properties. However, viscous damping in liquids significantly reduces the measurement sensitivity. This study proposes convolutional neural network (CNN) vibration spectrum analysis to evaluate the highly sensitive vibration states of nanomechanical resonators, which are useful for in-liquid measurements. This research was carried out through the measurement of acetone concentration. First, we compared the concentration classification ability between the proposed and conventional methods and determined that the proposed method of analyzing vibration spectral changes using the CNN model can provide higher measurement sensitivity than the conventional measurement method of observing resonance properties changes and comparing the values for each measurement condition. This result shows that CNN-based spectral analysis is effective for the vibration spectra of in-liquid measurements. Next, gradient-weighted class activation mapping (Grad-CAM) was applied to verify which frequency bands are important for concentration classification in CNN model decision-making. The vibration states in these frequency bands were analyzed in terms of oscillation modes. This analysis revealed significant oscillation modes of the nanomechanical resonator in the liquid environment. Notably, in addition to the resonance states utilized in the conventional method, several other oscillation modes were found to be significant for measurements. This finding suggests that these oscillation modes may be highly sensitive for measurements in liquid environments. Among these oscillation modes, the mode with very small amplitude is highly promising for achieving unprecedented levels of sensitivity in sensing technologies.

Fast nonlinear scattering of runaway electron beams through resonant interactions with plasma waves

Abstract The resonant interaction between a runaway electron (RE) beam and a reactor-grade background plasma is investigated through two-dimensional particle-in-cell simulations, employing a simplified model of the system. The temporal evolutions of the electron momentum distribution function for two separate initial beam energies (1 and 10 MeV) are tracked, revealing the occurrence of plasma wave growth concomitant with pitch angle scattering or momentum distribution diffusion within the RE beam. Notably, we identify and confirm the dependence of the dominant resonance condition on the initial kinetic energy of the RE beam. Furthermore, we quantify the effect of particle-wave interactions on the RE momentum distribution diffusion by assessing the average kinetic energy flux from the RE distribution function.

Vibration control of FG-pipe conveying fluid using a nonlinear absorber with nonlinear damping in longitudinal direction

This study investigates the use of a nonlinear absorber with nonlinear damping to mitigate the transverse vibrations of a fluid-conveying pipe made of functionally graded materials (FGM). The nonlinear effects arising from the pipe’s curvature and inertia are precisely accounted for in the equation of motion. The governing equations of the FGM pipe-nonlinear absorber system are derived using extended Hamilton’s principle and solved using the method of multiple scales. 1:1 internal resonance condition between the first natural frequency of the pipe and absorber is explored for transferring energy from the pipe to the absorber based on the modal interaction. The frequency-amplitude curves reveal that as the power-law index (n) increases, the nonlinear hardening behavior of the pipe decreases, while that of the absorber increases. Incorporating nonlinear damping in the absorber is found to further improve vibration suppression, leading to a strongly modulated response that reduces the pipe vibrations by over 84.57% and the absorber vibrations by over 94.57%. The impact of the absorber’s nonlinear stiffness on the strongly modulated response is also investigated, indicating that excessively high stiffness can cause the disappearance of this beneficial behavior. The findings of this study provide valuable insights into the optimal design of FGM pipes conveying fluid and the integration of nonlinear absorbers with nonlinear damping for enhanced vibration mitigation.

Development of Simplified Methods for Levitation Force Distribution in Maglev Vehicles Using Frequency Ratio Tests.

Maglev vehicles apply the entire vehicle load uniformly onto bridges through levitation forces. In assessing the dynamic characteristics of the maglev train-bridge coupling system, it is reasonable to simplify the distributed levitation force as a concentrated force. This article theoretically derives the analytical response of bridge dynamics under the action of a single constant force and conducts numerical simulations for a moving single constant force and a series of equally spaced constant forces passing over simply supported beams and two-span continuous beams, respectively. The topic of discussion is the response of bridge dynamics when different degrees of force concentration are involved. High-precision displacement and acceleration sensors were utilized to conduct tests on the Shanghai maglev line to verify the accuracy of the simulation results. The results indicate that when simplifying the distributed levitation force into a concentrated force model, a frequency ratio can be used to analyze the conditions for resonance between the train and the bridge and to calculate the critical speed of the train; the levitation distribution force of a high-speed maglev vehicle can be simplified into four groups of concentrated forces based on the number of levitation frames to achieve sufficient accuracy, with the dynamic response of the bridge being close to that under distributed loads.

Fully heavy tetraquark resonant states with different flavors

We use the quark potential model to calculate the mass spectrum of the S-wave fully heavy tetraquark systems with different flavors, including the bcb¯c¯,bbc¯c¯,ccc¯b¯, and bbb¯c¯ systems. We employ the Gaussian expansion method to solve the four-body Schrödinger equation, and the complex scaling method to identify resonant states. The bcb¯c¯,bbc¯c¯,ccc¯b¯, and bbb¯c¯ resonant states are obtained in the mass regions of (13.2, 13.5), (13.3, 13.6), (10.0, 10.3), (16.5, 16.7) GeV, respectively. Among these states, the bcb¯c¯ tetraquark states are the most promising ones to be discovered in the near future. We recommend the experimental exploration of the 1++ and 2++ bcb¯c¯ states with masses near 13.3 GeV in the J/ψϒ channel. From the root-mean-square radii, we find that all the resonant states we have identified are compact tetraquark states. Published by the American Physical Society 2024

Making molecules in cavity.

Free molecules undergo processes with photons; in particular, they can undergo photoionization and photodissociation, which are relevant processes in nature and laboratory. Recently, it has been shown that in a cavity, the reverse process of photoionization, namely, electron capture becomes highly probable. The underlying mechanism is the formation of a hybrid resonance state. In this work, we demonstrate that the idea of enhanced reverse processes is more general. We discuss the case of the reverse process of photodissociation, namely, making a molecule out of separate atoms in a cavity. For bound electronic states, the interaction of atoms and molecules with quantum light as realized in cavities is known to give rise to the formation of hybrid light-matter states (usually called polaritons). In the scenarios discussed here, the hybrid light-matter states are resonance (metastable) states, which decay into the continuum of either electrons or of the fragments of a molecule. Resonances can substantially enhance the outcome of processes. In addition to the new resonant mechanism of molecule formation, the impact of the hybrid resonances on the scattering cross section of the atoms can be dramatic.