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As part of the development of advanced, data-driven methods for predictive maintenance of railway infrastructure, this paper analyzes and evaluates more realistic predictions of eigenfrequencies of railway bridges, also referred to as natural frequencies, based on a population of already assessed, measured existing bridges using regression techniques. For this purpose, Machine Learning (ML) techniques such as Polynomial Regression (PR), ANN and XGBoost are consistently evaluated and the application of the XGBoost algorithm is identified as the most suitable prediction model for these eigenfrequencies, usable for dynamic train-bridge interactions. The results of the post-processing are incorporated into the safety architecture for bridge verification (risk management). The presented data-based techniques are a steppingstone towards digitalization of structural health monitoring and offer safety and longevity of the railway bridges. Furthermore, the use of these methods can save costs that would be incurred by physical in-situ measurements. The types of bridges analyzed with ML are Filler Beam Bridges (FBE), which outnumber other construction types of bridges in Germany (DB InfraGO AG). This methodology is applicable to any bridge type as long as sufficient data are gathered for training, validation and testing.

This study employs the wave dispersion relation of periodic structures to demonstrate the dual resonance mechanism occurring as a train traverses a series of bridges. Dual resonance occurs when the resonant speeds of both the train and the bridge coincide, leading to resonance in the bridge and progressively amplifying the train’s responses from the front to the rear carriages. This phenomenon involves a complex interaction between the bridge’s temporal resonance and the train’s spatial periodicity. This interaction creates a unique spatiotemporal vibration pattern. To understand the wave dispersion in this periodically coupled system, we model it as two interconnected spring-mass systems connected by contact springs. The analytical approach allows us to identify the key parameters governing the wave dispersion relation and wave-transmitting phenomena between two periodic structures. The wave dispersion analysis reveals that continuous beams have broader passbands, allowing them to transmit more waves and vibrations from moving trains than simply supported beams. This reduces resonance and leads to smoother system performance for continuous beams. Consequently, when a train travels on an equal-span continuous bridge at its resonance speeds, its vibrations can be efficiently transmitted to the bridge through these passbands, thereby mitigating resonance.

Vehicle–track beam coupling resonance greatly influences the vibration response of the suspended permanent (SPML) system. Therefore, the study established the coupled dynamic model of the SPML train and the track beam using. The model is used to analyze the dynamic response of SPML trains when passing through the long-span flexible track beam at resonance speed. The accuracy of the model was verified by field tests, which simulated and compared the dynamic responses of maglev train and track beam systems at different running speeds. Furthermore, the coupled vibration response of the train and track beam at resonant speed are investigated to gain insight into the mechanism and vibrational properties of the SPML system in a resonant background. It shows that the dominant frequency of the train, suspension frame, and track beam is 6.74Hz. They result in resonance in the SPML system at 30km/h. Further analysis shows that adjusting the vertical distance between the mass center of the vehicle and the track beam can effectively alleviate the resonance between the vehicle and the track. Additionally, deformation at the ends of the long-span track beams affects the levitation force and gap of the suspension frame, offering valuable guidance for SPML system design.

Dynamic characteristics of a room play a significant role in its acoustic performance. Among other dynamic parameters, the resonance frequency and modal damping are two most important factors in a room’s acoustic behavior and the efficiency of the active/passive absorbers used to control that behavior. In this paper, the experimental modal analysis (EMA) techniques will be exploited for the purpose of identification of the resonance and modal damping of a listening room, using different excitation sources and various room configurations and the accuracy of the results will be examined.

We consider the one-dimensional discrete Schrödinger operator on ℤ, and study the relation between the generalized eigenstates and the asymptotic expansion of the resolvent for the threshold 0. We decompose the generalized zero eigenspace into subspaces, some of which correspond to the bound states or the resonance states, only by their growth properties at infinity, and precisely describe the first few leading coefficients in the expansion using these subspaces. The generalized zero eigenspace we consider is the largest possible one, consisting of all solutions to the eigenequation. For the resolvent expansion, we implement the expansion scheme of Jensen–Nenciu [Rev. Math. Phys.13 (2001) 717–754] and [Rev. Math. Phys.16 (2004) 675–677] in its full generality.

We consider a $2\times 2$ system of 1D semiclassical differential operators with two Schrödinger operators in the diagonal part and small interactions of order $h^{\nu }$ in the off-diagonal part, where $h$ is a semiclassical parameter and $\nu$ is a constant larger than $1/2$. We study the absence of resonance near a non-trapping energy for both Schrödinger operators in the presence of crossings of their potentials. The width of resonances is estimated from below by $Mhlog(1/h)$ and the coefficient $M$ is given in terms of the directed cycles of the generalized bicharacteristics induced by two Hamiltonians.

In this paper, some properties of resonances for multi-dimensional quantum walks are studied. Resonances for quantum walks are defined as eigenvalues of complex translated time evolution operators in the pseudo momentum space. For some typical cases, we show some results of existence or nonexistence of resonances. One is a perturbation of an elastic scattering of a quantum walk which is an analogue of classical mechanics. Another one is a shape resonance model which is a perturbation of a quantum walk with a non-penetrable barrier.

We give a method to obtain estimates on distorted resolvents which we apply to the Stark effect with general potentials. This paper also contains a geometric perturbation theory which together with the estimates mentioned above, shows the existence of resonances and gives an upper bound on the width of resonances in various situations.

To provide insights into the modulation of neuronal activity by extremely low-frequency (ELF) magnetic field (MF), we present a conductance-based neuron model and introduce ELF sinusoidal MF as an additive voltage input. By analyzing spike times and spiking frequency, it is observed that neuron with distinct spiking patterns exhibits different response properties in the presence of MF exposure. For tonic spiking neuron, the perturbations of MF exposure on spike times is maximized at the harmonics of neuronal intrinsic spiking frequency, while it is maximized at the harmonics of bursting frequency for burst spiking neuron. As MF intensity increases, the perturbations also increase. Compared with tonic spiking, bursting dynamics are less sensitive to the perturbations of ELF MF exposure. Further, ELF MF exposure is more prone to perturb neuronal spike times relative to spiking frequency. Our finding suggests that the resonance may be one of the neural mechanisms underlying the modulatory effects of the low-intensity ELF MFs on neuronal activities. The results highlight the impacts of ELF MFs exposure on neuronal activity from the single cell level, and demonstrate various factors including ELF MF properties and neuronal spiking characteristics could determine the outcome of exposure. These insights into the mechanism of MF exposure may be relevant for the design of multi-intensity magnetic stimulus protocols, and may even contribute to the interpretation of MF effects on the central nervous systems.

Two dimensional plasmons in submicron transistors have attracted much attention due to their nature of promoting emission/detection of electromagnetic radiation in the terahertz range. We have recently proposed and fabricated a highly efficient, broadband plasmon-resonant terahertz emitter. The device incorporates doubly interdigitated grating gates and a vertical cavity into a high electron mobility transistor. The device operates in various modes: (1) DC-current-driven self oscillation, (2) CW-laser excited terahertz emission, (3) two-photon injection-locked difference-frequency terahertz emission, and (4) impulsive laser excited terahertz emission. Furthermore, the device can operate in completely different functionalities including ultrahigh-speed intensity modulation for terahertz carrier waves. This paper reviews recent advances on plasma wave devices.

In this paper, by using the coincidence degree theory, we consider periodic boundary value problem for fractional differential equation. A new result on the existence of solutions for above fractional boundary value problem is obtained.

We study the resonant behavior of a system consisting of a square array of multi-coated cylinders by calculating the effective dielectric constant of the system. The results were examined numerically using the finite element method.

Muon cycling dynamics for muon catalyzed fusion in heterogeneous solid layers are considered through decay of complex molecule . The suggested fusion system consists of three layers which are alternatively repeated. The first layer is D/T (deuterium, tritium) which provides molecules. The second layer is T₂ molecules which are used to slow down the muonic atoms and the third layer is D₂ molecules. The design is in a way in which dtμ, muonic deuterium and tritium molecules, are produced in resonance. It is shown, by considering muonic dynamics theoretically in a suggested heterogeneous system and determining its cycling rate by using a more advanced calculational method, that for equal deuterium, tritium concentration (C_d=C_t=0.5) in D/T layer and ϕ'=ϕ₀=ϕ=1 (relative density for each layer respectively and given in liquid hydrogen density LHD=4.25×10²²cm^-3), the muon cycling rate is optimum for the suggested heterogeneous system and has 15% enhancement with respect to the conventional D/T system. It is also shown that for ϕ₀<0.0003 the muon cycling rate in D₂ is almost stopped, and for ϕ₀≥1 muon cycling rate increases, but this is not recommended due to low and costly tritium availability.

According to the experimental results and practitioners' subjective experience, we report some hypotheses that may account for meditative phenomena during the practice of Zen-Buddhism. Orthodox Zen-Buddhist practitioners, aiming to prove the most original true-self, discover and uncover the inner energy or light on the way towards their goal. Perception of the inner light can be comprehended as resonance. Uncovering the inner energy optimizes physiological and mental health. In the meditation experiment, a significant correlation was observed between perception of the inner light and electroencephalographic (EEG) alpha blockage. We further examined this phenomenon by recording the EEG from subjects during a blessing that the subjects did not know being given. During the blessing period, significant alpha blocking was observed in experimental subjects who had been practicing meditation for years in preparation for being in resonance with the inner light. This report provides a new insight into the debate that meditation benefits our health.

We show that a nonlinear dynamical system in Poincaré–Dulac normal form (in ℝⁿ) can be seen as a constrained linear system; the constraints are given by the resonance conditions satisfied by the spectrum of (the linear part of) the system and identify a naturally invariant manifold for the flow of the "parent" linear system. The parent system is finite dimensional if the spectrum satisfies only a finite number of resonance conditions, as implied e.g. by the Poincaré condition. In this case our result can be used to integrate resonant normal forms, and sheds light on the geometry behind the classical integration method of Horn, Lyapounov and Dulac.

Envelope solitons of the Nonlinear Schrödinger equation (NLS) under quantum potential's influence are studied. Corresponding problem is found to be integrable for an arbitrary strength, s ≠ 1, of the quantum potential. For s < 1, the model is equivalent to the usual NLS with rescaled coupling constant, while for s > 1, to the reaction–diffusion system. The last one is related to the anti-de Sitter (AdS) space valued Heisenberg model, realizing a particular gauge fixing condition of the (1+1)-dimensional Jackiw–Teitelboim gravity. For this gravity model, by the Madelung fluid representation we derive the acoustic form of the space–time metric. The space–time points, where dispersion changes the sign, correspond to the event horizon, while the soliton solution to the AdS black hole. Moving with the above bounded velocity, it describes evolution on the one sheet hyperboloid with nontrivial winding number, and creates under collision, the resonance states which we study by the Hirota bilinear method.

Three-alpha resonance excited states has been theoretically explored by means of the α+α+α microscopic cluster model. The resonance parameters is determined by employing the Complex Scaling Method (CSM). Our model space is extended by including higher partial waves than the RGM+CSM calculation by Pichler¹. Our model has given the third 0⁺ state at 4~5MeV above the three-body threshold but the broad 0⁺ state, which was recently reported experimentally and overlapping with the 2⁺ state², has not been localized between the second and the third 0⁺ states. On the other hands, our model has given the second 2⁺ state about 2MeV and the third at 4~5MeV.

In the e⁺e^- annihilation processes , D⁺D^- near or above the threshold of , there are not only the resonance contribution , D⁺D^-, but also the continuum contribution through virtual photon directly , D⁺D^-. The amplitudes through virtual photon directly and through resonance can interfere seriously. We consider the continuum and interference effect in the production process in e⁺e^- annihilation. We find that the effect is significant near and above the threshold of the mesons.

Single-particle resonant states in Ca isotopes are studied systematically by real stabilization method (RSM) in coordinate space within the framework of the self-consistent relativistic mean field (RMF) theory. Phase shifts are obtained by scattering phase shift method. The resonant parameters (the energies, widths) are extracted by fitting energy and phase shift. Wave functions of resonances are obtained by matching conditions of bound and scattering states. Taking ⁶⁰Ca as an example, results are compared with corresponding results obtained from the analytic continuation in the coupling constant approach and the scattering phase shift method. Satisfied agreements are found. The rules of resonant parameters changing in Ca isotopes are also analyzed.

The systems with J = 0 and J = 1 are dynamically investigated within the framework of two constituent quark models: the chiral quark model and the quark delocalization color screening model. The model parameters are taken from our previous work, which gave a good description of the proton–antiproton S-wave elastic scattering cross-section experimental data. The elastic scattering processes with coupling to state are studied. The results show that, there is no s-wave bound state as indicated by an enhancement near the threshold of in J/ψ decay. However, a resonance state is given in the quark delocalization color screening model.