Narrow Results

Submerged floating tunnels (SFTs) are intricate structures influenced by a complex interplay of parameters such as buoyancy-weight ratio, immersion depth, water depth configuration, cable inclination, and tension distribution. To improve the assessment of SFT service performance, this paper introduces a computational model that evaluates the static behavior of SFTs, deriving a tension distribution formula aimed at minimizing deflection based on the interdependence of these parameters. Building on this model, the study further examines the hydrodynamic response of SFTs under wave conditions, analyzing variations in immersion depth, cable inclination angles, wave heights, and wavelengths. Furthermore, based on the static analysis, this study emulated the equivalent load of cable breakage and examined the subsequent dynamic response before and after under wave conditions. Finally, the response results were compared with the static analysis of the structure, mutually verifying the accuracy of the model. The results indicate that optimizing cable tension distribution can significantly reduce maximum deflection and bending moments, enhancing structural stability. Moreover, increased cable tension contributes to overall stiffness, thereby mitigating vortex-induced vibrations. Cable inclination also plays a crucial role; smaller inclination angles provide greater lateral constraints but reduce vertical constraints, with an optimal range identified between $45^{\circ }$ and $60^{\circ }$. Additionally, higher wave heights and shallower immersion depths amplify the hydrodynamic response, with certain conditions exciting higher-order vibration modes. Overall, downstream cable tensions tend to surpass those upstream, except under specific wave periods and inclinations. Under the condition of cable breakage, the structural stiffness decreases, leading to an increase in dynamic response. Meanwhile, the cable tensions on the opposite side of the same cross-section slightly increase, whereas the cable forces on the same side of different cross-sections significantly increase. These insights are valuable for the design and maintenance of SFTs across diverse environmental conditions.

We analyze a spatial susceptible-infected epidemic model using cellular automata and investigate the relations between the power-law distribution of patch sizes and the regime of invasion. The obtained results show that, when the invasion is in the form of coexistence of stable target and spiral wave, power-law will emerge, which may provide a new insight into the control of disease.

Quantum mechanical states are normally described by the Schrödinger equation, which generates real eigenvalues and quantizable solutions which form a basis for the estimation of quantum mechanical observables, such as momentum and kinetic energy. Studying transition in the realm of quantum physics and continuum physics is however more difficult and requires different models. We present here a new equation which bears similarities to the Korteweg–DeVries (KdV) equation and we generate a description of transitions in physics. We describe here the two- and three-dimensional form of the KdV like model dependent on the Plank constant $\hslash$ and generate soliton solutions. The results suggest that transitions are represented by soliton solutions which arrange in a spiral-fashion. By helicity, we propose a conserved pattern of transition at all levels of physics, from quantum physics to macroscopic continuum physics.

The classical limit of wave quantum mechanics is analyzed. It is shown that the basic requirements of continuity and finiteness to the solution of the form ψ(x) = Ae^{i ϕ (x)} + Be^{-i ϕ (x)}, where and W(x) is the reduced classical action of the physical system, give the asymptote of the wave equation and general quantization condition for the action W(x), which yields the exact eigenvalues of the system.

One important function of the port is to protect ship or some other facilities from wave attack so as to stably handle cargoes. In current design codes, there are mainly two expressions of the tranquility standard of harbor basin: one is the acceptable wave height in front of wharf; the other is the tolerable amplitude of ship motion. However, ship motions are affected by some more factors simultaneously, such as wave frequency, wave height, incident wave direction, ship properties and wharf type. This paper presents some computed results of the wave-induced ship motions on the basis of a port case in China. First, the Simple Green Function method is employed to solve and compare the 2-dimension hydrodynamic coefficients in front of open or bulkhead wharf. The results show a great difference between them. Then, this paper computes and discusses the ship motions in front of open wharf at different wave frequencies and incident wave directions.

The equation of motion for a particle moving in complex space is obtained and then solved. The interaction between the real and imaginary components of motion can produce what can be regarded as a wave motion in real space. The formation of interference patterns and polarization of a matter wave can be accounted for by the particle’s motion in complex space. The deterministic particle view of a free particle can then be reconciled with its dual probabilistic wave picture but the formulation is entirely in complex space.

The concealed microcracks in shield tunnel lining present the characteristics of being of small size, unknown shape, and are difficult to detect. Based on the finite-difference time domain (FDTD) approach, this study proposed a new construction method of a refined grid accommodating and combining the variable shapes of microcracks, and capable of designing cross type, mesh type, and wave type microcrack models. The proposed new method also configured steel bars in the models to simulate actual engineering conditions, and characteristic response images of the models under different working conditions were obtained using ground penetrating radar (GPR) technology, which were then compared and analyzed to identify the imaging characteristics and differences of microcracks with variable geometric shapes. The waveform, amplitude, and time span of the characteristic single channel signal were furthermore studied. The results showed that the new method could successfully simulate the GPR characteristic response images of 0.5mm microcracks of diverse geometric shapes. When the microcracks were wavy, their real shape could only be determined after signal pre-processing; the density and quantity of steel bars directly affected the appearance of microcrack characteristic signals; the greater the density and quantity of steel bars, the greater the interference on the waveform, amplitude, and time-frequency range of electromagnetic wave signals; a special correlation existed between the maximum mean root square value of the amplitude and the single channel signal of the cracks. Moreover, the finding that the extension in time and distance in the GPR time distance profile intersected with the cracks was deemed potentially to provide fresh insights into identifying the characteristic points of the cracks in the GPR images. The new method proposed in this study successfully obtained the GPR numerical simulation images and characteristic signals of microcracks with variable geometric shapes. Through the processing and analysis of the characteristic response signals of microcracks, the conclusions obtained were considered to provide an interpretation basis for the detection of microcracks in practical engineering.

A significant drawback of the symmetry set evaluation for a 2D shape using the wave diffusion process¹ is its slow execution time caused, in large part, by the diffusion step. We first recall the need for a diffusion process. A parallel implementation of the wave diffusion algorithm on a transputer network is presented. A faster alternative approach to detect the symmetry set, which we call the normal transform, and which is similar to the wave propagation mechanism, is described.

Intracellular cardiac Ca²⁺ handling involves interactions of numerous distinct cellular and macromolecular structures. Such interactions coordinate the complicated behaviors of individual processes into spatial and temporal coherent patterns of Ca²⁺ sparks, oscillations and traveling waves. Understanding the dynamical behaviors and functional roles of intracellular Ca²⁺ handling requires not only detailed experimental information about subcellular structures and dynamics, but also useful tools to integrate and analyze this information. This requires interactions between experimental and simulation results within a virtual cell.

A novel adaptive strategy, dubbed m-adaptation, is developed for solving the acoustic wave equation (in the time domain) on square meshes. The finite element, the finite difference and a few other more recent methods are shown to be particular members of the mimetic family. Analysis of the parametric family of mimetic discretization methods is performed to find the optimal member that eliminates the numerical dispersion at the fourth-order (as in Ref. 1) and the numerical anisotropy at the sixth-order (higher than in Ref. 1). The stability condition for the optimal method is derived that turns out to be comparable to the classical Courant condition. The numerical experiments show that the new approach is consistently better than the classical methods for reducing a long-time integration error.

The effect of cable capacitance in the classical key distribution system based on resistors and band-limited noise sources is re-examined. Both the lumped element analysis and the transmission line analysis are performed. As long as the cable capacitance and inductance are fully taken into account, the lumped element analysis and the transmission line analysis generate identical results. When the cable is bootstrapped with a driven shield, the capacitance can be neglected, but the transit time should not be overlooked.

Recently, the quantum spectrum of black BIons has been considered and their entropies have been calculated. Generalizing this model to a tube of water which interacts with DNA waves, its quantum spectrum and entropy could be obtained. A DNA can emit two types of waves, including electromagnetic waves (EMS) and topoisomerase-like ones. EMS carry messages of a DNA and help it to communicate with other DNAs and also pure water. Topoisomerase-like waves open packings of a DNA and copy its genetic information. Both of these waves could interact with pure water and change its entropy and quantum spectrum.

A horizontal two-dimensional finite element model is developed in order to estimate the process of scour around a large-scale cylinder due to waves. The present model differs from previous models in the sense that the wave model is based on an elliptic mild slope equation and the sediment transport induced by the steady streaming is considered. The current induced by the gradient of radiation stress is considered and calculated using a depth integrated shallow water equation. The contributions of the Lagrangian drift velocity to the scour is also considered in this model. The model is validated against a few cases where experimental data are available. The comparison of the calculation results with the experimental data indicates that the present numerical model predicts the scour around a large cylinder reasonably well. The effects of Keulegan–Capenter (KC) number, the grain size of sediments and the model scale on scour around a large cylinder are also investigated.

Most of the existing sediment transport models are not synchronously driven by both the wave field and the flow field. This paper describes a 3D sediment transport model with waves and currents directly coupled within the model to continuously account for different-scale activities especially those that have significant contribution to local sediment transport processes such as formation of sediment plumes and turbidity maxima. A practical issue in modeling coastal sediment transport, besides the concern of model accuracy, is the efficiency of the model. In the present model, the wave action equation, instead of the computational demanding elliptic mild-slope equation, is used to calculate the wave parameters. The wave action equations take into account wave refraction and diffraction as well as the tidal hydrodynamic modification. The calculation of the wave and current forcing is coupled during the time marching process so that the effects due to short-term activities can be considered. The model has been verified against laboratory measurements and has also been applied to simulate actual sediment transport situations in the Pearl River Estuary (PRE), China. It has been quantitatively shown that the suspended sediment concentration in the PRE increases significantly when waves are present. Sediment deposition occurs at the upstream region of the PRE while erosion takes place mostly at the down-estuary region due to exposure to wave actions.

This paper deals with the development of scour holes in time and space around individual offshore monopiles. It is based on physical flume tests of a model-scale pile subjected to current and/or irregular water waves. The main focus is on backfilling, i.e. the wave-induced or current-wave-induced deposition of sediment into holes that have been previously scoured. The development of the scour depth, scour volume and a so-called scour shape factor is quantified which may be useful to understand and benchmark the development of scour holes.

The method of Lin and Huang [Lin and Huang [2004] “Decomposition of incident and reflected higher harmonic waves using four wave gauges,” Coast. Eng.51(5), 395–406.] (LH) is improved for resolution of incident and reflected strongly nonlinear regular waves in shallow waters with measurements of four stationary wave gauges. For first harmonics, wavenumbers, amplitudes and initial phases are obtained by using a nonlinear least squares method. For higher harmonics, wavenumbers of free and bound modes are determined from linear dispersion relation and multiple of first-harmonic wavenumbers, respectively, and the other unknowns are solved by using a linear least squares method. Auto-correlation function is used to determine fundamental wave period for gaining a good performance of Fourier transform. The efficiency and accuracy of the present method are demonstrated by using artificial data and numerical flume data. It is also demonstrated that the present method is less sensitive to signal noise and gauge spacings. Comparison between the present method and the LH method indicates the necessity of employing nonlinear method in determining fundamental wavenumbers of nonlinear shallow-water waves. Finally, the present method is extended to account for obliquely-incident waves. Sensitivity tests indicate the robustness of the extended method with respect to incident angles. Relative position of gauges in the array for avoiding singularity is suggested.

Clearance is inevitable in the deployable mechanisms due primarily to the kinematic function requirements. This phenomenon affects the dynamic performances of deployed structures negatively. In this paper, the wave analysis of dynamic characteristics of planar structures with revolute clearance joints is developed by spectral element method. First, the spectral element model of revolute clearance joints is established. The radial and tangential springs and damping coefficients of revolute clearance joints are evaluated based on the contact model of elastic foundation. Then, the wave equations of two beams connected by a revolute clearance joint are derived, and extended to the case of multiple beams connected by revolute clearance joints. Finally, the dynamic response is analyzed for planar structures with single revolute clearance joint and multiple revolute clearance joints under the impact load. The wave propagation rules in planar structures with revolute clearance joints are revealed.

The purpose of this research work is to study the diffraction of surface gravity waves propagating through rectangular porous medium in three dimensions. The considered porous structure consists of dense arrays of surface piercing vertical cylinders. Experiments for different regular wave conditions have been carried out, especially for three-wave frequencies. The experimental data of wave refraction–diffraction and reflection have been compared to computed results from potential linear theory solved with an integral matching method. Comparison with a previous 2D study about wave propagation through porous medium in a 10 m long wave flume is also discussed in order to highlight the refraction–diffraction effect due to the porous structure.

Our study starts from the interaction of a thin liquid layer and surface acoustic waves in an isotropic semi-infinite substrate, and we obtain the relationship between wave velocity and thickness of ideal fluid layer. This result is similar with earlier experimental and research results. We further extend substrate to an isotropic semi-infinite plate, at which both symmetric and anti-symmetric modes of a plate can be captured as thickness of liquid layer becomes extremely thin. This result is very close to plate vibrations without the liquid layer. Finally, we analyze the characteristics of surface acoustic waves propagating in an anisotropic semi-infinite solid and plates covered with an ideal liquid layer. It is observed from an ST-cut quartz crystal substrate that there are many displacement modes and corresponding velocities due to the interaction of waves in the plate and liquid layer.

The propagation behaviors of surface acoustic waves in an isotropic semi-infinite solid and infinite plate with initial stress field are investigated, and we obtain the phase velocity equations of Rayleigh waves in a semi-infinite solid and infinite plate. By comparing surface acoustic waves velocity in plate under initial stress with that without initial stress, it is clear that velocity of surface acoustic waves are evidently affected by initial stress. When the stress is in the same direction of the propagation of the surface acoustic waves, the change of the wave velocity of the surface acoustic waves has certain relation to the stress within small numerical value of stress.