Wave Form Research Articles

Study on copper-stainless steel explosive welding for nuclear fusion by generalized interpolated material point method and experiments

The thick copper stainless steel composite plate is an important component of the cooling coil terminal box of international nuclear fusion reactors. The composite rate, tensile strength, shear strength, and interface waveform of the metal plate are also far higher than the requirements of conventional explosive welding technology. It is difficult to obtain the best technical process parameters in a short time solely relying on conventional explosive welding tests. In order to solve the above-mentioned technical difficulties in explosive welding, this article applies the generalized interpolation material point method (GIMP) based on the explosive welding window, metal elastic-plastic mechanics, and explosive detonation theory to conduct macroscopic three-dimensional and microscopic two-dimensional numerical simulations of the copper stainless steel explosive welding process and the composite interface wave formation process, respectively. The experimental results demonstrate that the GIMP has significant advantages in numerical calculation and analysis for the explosive welding problem of high-speed impact collision of metal plates driven by explosive detonation, and it can effectively solve the technical problems of high technical specifications, low explosive processing composite rate, and low interface strength of large thickness copper stainless steel composite plates used in nuclear fusion.

Phase transitions in 2D multistable mechanical metamaterials via collisions of soliton-like pulses

In recent years, mechanical metamaterials have been developed that support the propagation of an intriguing variety of nonlinear waves, including transition waves and vector solitons (solitons with coupling between multiple degrees of freedom). Here we report observations of phase transitions in 2D multistable mechanical metamaterials that are initiated by collisions of soliton-like pulses in the metamaterial. Analogous to first-order phase transitions in crystalline solids, we observe that the multistable metamaterials support phase transitions if the new phase meets or exceeds a critical nucleus size. If this criterion is met, the new phase subsequently propagates in the form of transition waves, converting the rest of the metamaterial to the new phase. More interestingly, we numerically show, using an experimentally validated model, that the critical nucleus can be formed via collisions of soliton-like pulses. Moreover, the rich direction-dependent behavior of the nonlinear pulses enables control of the location of nucleation and the spatio-temporal shape of the growing phase.

Stability investigation of an implicit difference scheme for a nonlinear transport equation

In this paper, we investigate the stability with respect to initial data in the uniform norm of an implicit difference scheme approximating a nonlinear transport equation. An iterative process is used to implement the difference scheme. The convergence of the iterative process and the stability of the difference scheme are proven in the case of initial data guaranteeing the absence of shock waves. In the case of the occurrence of shock waves, estimates of the growth of spatial derivatives at each time layer are obtained. An adaptive computational algorithm for solving the transfer equation during the formation of shock waves is built.

Modeling Study of Factors Determining Efficacy of Biological Control of Adventive Weeds

We model the spatiotemporal dynamics of a community consisting of competing weed and cultivated plant species and a population of specialized phytophagous insects used as the weed biocontrol agent. The model is formulated as a PDE system of taxis–diffusion–reaction type and computer-implemented for one-dimensional and two-dimensional cases of spatial habitat for the Neumann zero-flux boundary condition. In order to discretize the original continuous system, we applied the method of lines. The obtained system of ODEs is integrated using the Runge–Kutta method with a variable time step and control of the integration accuracy. The numerical simulations provide insights into the mechanism of formation of solitary population waves (SPWs) of the phytophage, revealing the factors that determine the efficacy of combined application of the phytophagous insect (classical biological method) and cultivated plant (phytocenotic method) to suppress weed foci. In particular, the presented results illustrate the stabilizing action of cultivated plants, which fix the SPW effect by occupying the free area behind the wave front so that the weed remains suppressed in the absence of a phytophage.

Nonreciprocal propagation of bending waves in spatiotemporally modulated prestressed beam

Breaking time or/and spatial symmetry can lead to unprecedent mechanical responses of a structure, the design of which is usually very intricate. This paper proposes a simple design of a beam structure with spatiotemporal modulation. In fact, a time-varying axial load applied to the ends of an elastic beam will induce space-time dependent axial force propagating in the form of longitudinal wave in the beam, which can modulate spatiotemporally the propagation of transverse bending waves. The governing equation is derived, of which the Floquet solution leads to a quadratic eigenvalue problem that can be solved for the frequency as a function of the wavenumber. Theoretical results show the existence of asymmetric wavenumber bandgaps and the unique dispersion diagram which is not periodic with respect to time or space. The breaking of temporal symmetry enables nonreciprocal propagation of transverse bending waves, which is confirmed by the finite element simulations. This modulation method offers promise for applications in the fields of elastic wave filter, frequency converter and magnitude amplifier.

An ensemble of ResNet model for classification of Parkinson disease

Parkinson disease (PD) is one of the neurological illnesses incurred. However, there is a no chance to recognize PD. A fine motor symptom has been identified in this study. A group of patients with PD, as well as the healthy group, is used in the research. The authors have developed a technique that can determine whether a patient has PD or not. Using deep learning methods, the same design generalizing neural networks in the brain can be solved. The categorization of patients with PD and non-PD behavior is found from the analysis of spiral and wave forms using CNN model. Various CNN models were used in the experiment by transfer learning and spiral and wave data sketches. With the help of spiral sketching, the system achieved an accuracy of 96.67% using the ResNet50 model. The main objective of this paper is to explore the application of transfer learning, which improved the performance of the model.

Water droplet energy harvesting

AbstractHarnessing abundant kinetic water energy in diverse forms of river flows, ocean waves, tidal currents, raindrops, and others, is highly attractive to ease the energy crisis and satisfy the demands of scattered sensor network nodes in the Internet of things. Among them, raindrops, widely and ubiquitously distributed in nature and ambient living life, have been extensively explored and regarded as significant renewable energy carriers. Extensive efforts have been made to investigate droplet‐based electricity nanogenerators in fundamental mechanism, performance, and applications for achieving sustainable energy demands of the rapidly developing society over the past decade. In this review, we introduce the remarkable progress in this field and discuss the fundamental mechanisms of droplet energy harvesting technology for achieving high‐power generation. More significantly, a systematic review of droplet energy harvesting in different two‐phase interfaces, including liquid–solid, liquid–liquid, and liquid–gas interfaces, is provided. Finally, this survey reveals that droplet‐based electricity generators present vast potential in the power supply. At the same time, several development challenges and prospective solutions are discussed to spur future technological advancements.

Features of otosurgery in children after blast injuries

An explosion is a process that rapidly releases a huge amount of energy in the form of heat, kinetic energy, and high-pressure shock waves. Since the organ of hearing is most susceptible to pressure changes, damage to the sound-conducting or sound-receiving systems is inevitable in case of an explosive injury. This article examines the mechanism of formation of explosive injuries of the middle and inner ear in children and adolescents, the features of diagnosis and tactics of surgical reconstructive treatment of explosive ear injuries based on the data available in the scientific literature and their own experience.

КОНЦЕПЦИЯ МОДЕЛИ МОРОЗНОГО ВОЗДЕЙСТВИЯ НА БЕТОН МОРСКИХ СООРУЖЕНИЙ

A conceptual approach is presented to predicting the durability of concrete under conditions of frost exposure and strong saturation based on the actual work of concrete in the structures of port facilities on the sea coast of the south of the island. Sakhalin. It is shown that the lack of methods for predicting concrete corrosion under frost exposure, despite the large amount of theoretical and experimental work on this topic, is due to the diversity and synergistic effect of factors that determine durability. It has been established that the multicyclic effect of sign-variable temperatures due to sea tides is not always the determining critical indicator of severity for the zone of variable level. Non-freezing water in the port waters and severe hydrometeorological conditions in the form of strong waves predetermine the icing of structures throughout the winter period. This factor in certain cases can be critical for concrete. Based on the results of the study of the state, properties and temperature-humidity regime of concrete in the structures of the zone of variable water level and the generally accepted theoretical principles of frost destruction of concrete, it is proposed to predict its service life in the zone of variable level of port facilities based on the concept of a two-stage process of frost corrosion. The possibility of predicting the durability of concrete based on scenario modeling of the process of development of the system of pore structure of the cement matrix, depending on its parameters by the beginning of frost exposure and the mechanism of freezing of concrete in structures, is shown.

Peculiarities of leakage of the electromagnetic waves from striations

It is well-known that an ordinary (O-mode) high frequency (HF) electromagnetic (EM) wave radiated into the ionosphere generates in the F-region upper-hybrid resonance (UHR) oscillations trapped in small-scale elongated plasma depletions (striations). Striations are not ideal resonators for UHR oscillations. There is some leakage of the HF energy from striations in the form of Z-mode waves. This result obtained in the quasi-electrostatic approximation is partly reconsidered in the present paper. It is shown in the 2D case that two EM waves (instead of one Z-mode) propagate from each side of a striation. The lowest eigenmodes of the electrostatic oscillations trapped in a striation excite at particular heights Z-mode waves that propagate significantly higher than the reflection height of the initial O-mode wave. This result exists for different angles of the O-mode radiation with respect to the vertical (both more and less than the critical angle).

Magneto-acoustic coupling: Physics, materials, and devices

Acoustic wave in solid has two modes of propagation: the bulk acoustic wave (BAW), which propagates inside solid in the form of longitudinal or transverse wave, and the surface acoustic wave (SAW), which is generated on the surface of solid and propagates along the surface. In acoustic radio frequency (RF) technologies acoustic waves are used to intercept and process RF signals, which are typified by the rapidly developing RF filter technology. Acoustic filter has the advantages of small size, low cost, steady performance and simple fabrication, and is widely used in mobile communication and other fields. Due to the mature fabrication process and well-defined resonance frequency of acoustic device, acoustic wave has become an extremely intriguing way to manipulate magnetism and spin current, with the goal of pursuing miniaturized, ultra-fast, and energy-efficient spintronic device applications. The integration of magnetic materials into acoustic RF device also provides a new way of thinking about the methods of acoustic device modulation and performance enhancement. This review first summarizes various physical mechanisms of magneto-acoustic coupling, and then based on these mechanisms, a variety of magnetic and spin phenomena such as acoustically controlled magnetization dynamics, magnetization switching, magnetic domain wall and magnetic skyrmions generation and motion, and spin current generation are systematically introduced. In addition, the research progress of magnetic control of acoustic wave, the inverse process of acoustic control of magnetism, is discussed, including the magnetic modulation of acoustic wave parameters and nonreciprocal propagation of acoustic waves, as well as new magneto-acoustic devices developed based on this, such as SAW-based magnetic field sensors, magneto-electric antennas, and tunable filters. Finally, the possible research objectives and applications of magneto-acoustic coupling in the future are prospected. In summary, the field of magneto-acoustic coupling is still in a stage of rapid development, and a series of groundbreaking breakthroughs has been made in the last decades, and the major advances are summarized in this field. The field of magneto-acoustic coupling is expected to make further significant breakthroughs, and we hope that this review will further promote the researches of physical phenomena of the coupling between magnetism and acoustic wave, spin and lattice, and potential device applications as well.

Capillary waves and dendritic instability on radial Hele–Shaw displacements

The displacement of a fluid by another less viscous one in isotropic quasi-two-dimensional Hele–Shaw cells typically leads to viscous fingering patterns characterized by repeated tip-splitting and side-branching. When anisotropy is present, the viscous fingering patterns are replaced by dendritic instability. In isotropic cells, Couder et al. [“Dendritic growth in the Saffman-Taylor experiment,” Europhys. Lett. 2, 437 (1986)] induced the growth of a dendritic finger by placing a small isolated bubble in contact with the tip of a finger. Moreover, in rectangular displacements, Kopf-Sill and Homsy [“Narrow fingers in a Hele–Shaw cell,” Phys. Fluids 30, 2607–2609 (1987)] observed for specific ranges of modified capillary numbers, Ca, that narrow fingers develop into dendritic patterns after carefully cleaning the Hele–Shaw cell with a soap solution. In the current work, by injecting air to radially displace a lubricant oil with strong adsorption properties, we observe for the first time the growth of dendritic instability in displacements confined in isotropic Hele–Shaw cells in the absence of air bubbles driving the fingertip. These structures are driven by the formation of capillary waves inside the finger adjacent to the Hele–Shaw surfaces. Furthermore, we compare displacements of different materials at similar high Ca values and obtain significantly different morphological results, indicating the pattern formation may not scale with this parameter in this range. Discrepancies are explained based on both wetting and inertia effects.

The Dragon Image of Ly-Tran Dynasty: Application in Historical Comic Characters

The theme of decorative patterns of lotus, chrysanthemum, dragon, cloud, and water waves is a commonly used image in Ly-Tran's decorative designs that are still used today. Others are an endless source of inspiration for application design and themes that have become fashion trends with ethnic elements. Contributing to promoting and preserving the value of Vietnamese fine art in the modern period, this article surveys and analyses the formation and transformation of water waves through the ages and their applications in contemporary packaging design. The research shows that the water wave pattern is a long-standing symbol and decorative pattern in ancient Vietnamese visual arts; it not only has artistic value but also contains religious and spiritual value and the profound Eastern philosophical concept, reflecting the constant rotation of life on each winding rhythm. This pattern under the Ly-Tran dynasties has both practical significance and represents the peak shaping value of the dynasty. Integrating the rhythm of contemporary life into application design, using water wave patterns in packaging design, aims to promote and spread more widely to the public in modern life. This article aims to study the social context and creative forms of recreating and using water wave motifs in general application design and packaging in the field of art and design today. At the same time, analysis of new design methods continues to develop, convey, and even expand the symbolic meaning of the motifs through the aesthetic orientation of contemporary people and by inheriting and promoting traditional good culture.

Волны в морской акватории вблизи мыса Свободный (юго-восточная часть о. Сахалин)

A study of wave processes near Cape Svobodny on the south-eastern coast of the island Sakhalin using autonomous wave recorders and a weather station has been performed. Analysis of five-month data of sea level and temperature, atmospheric pressure and wind speed revealed that there are no significant peaks for wind and infragravity (IG) waves in the wave period range 2–600 s, and the wave energy is lower at the point protected by Cape Svobodny. During storms, there is an increase in the energy of IG waves. Waves detected at periods of 14.2 seconds, 3.62 minutes, and 8.85 minutes are related to swell and edge waves propagating seaward. For explanation of short waves, the Longuet-Higgins and Stewart theory was used which describes the dispersion of swell in the surf zone and the formation of free waves. Edge waves were analyzed using the Lamb model and the Bessel function of the first kind of zero order. Modelling of wave processes propagating shoreward revealed the presence of IG waves with periods of 20–110 seconds and edge waves with periods of 4.27–7.63 minutes, confirmed by the dispersion relation for Stokes waves on a sloping bottom. Sea water temperature fluctuations of more than 7 °C with periods of 3–100 minutes affect the propagation of waves with periods longer than 3 minutes, destroying the edge and leaky waves. Analysis of wind wave characteristics showed no significant wave processes, including wind waves, in the 2–20 second period range. The maximum wave height was observed during prolonged southern winds associated with a cyclone. This study is important for understanding wave processes in this area, aiding in predicting their behaviour and impact on the coastline.

Effect of porosity on rapid dynamic compaction of nickel nanopowder.

The shock-loading behavior of nanomaterials requires careful investigation because these complex systems are widely used in environments subjected to impulsive loads. Planar plate impact experiments are conducted to study shock compaction waves in 94% porous nickel powder containing spherical ∼55 nm particles in the pressure and strain rate ranges of 0.1-0.4 GPa and 106-107 s-1, respectively. The distinct two-step structure of these waves is captured by a laser velocimetry technique with high time resolution. This structure is caused by the formation of faster precursor waves traveling ahead of main compaction waves. The complexity of the shock Hugoniot curve of the tested nanomaterial is described using the obtained two-wave data and earlier results for higher pressures. The effect of initial porosity on the fronts of both waves and compressed states behind them is demonstrated using the current data and those that were collected previously for 50% porous samples of similar nanopowder.

HORIZONTAL SINUSOIDAL WAVY FORM PLATE-FIN HEAT SINKS FOR NATURAL CONVECTION HEAT DISSIPATION

The plate-fin heat sink geometry was modified to have the fin form sinusoidal wave shape in the horizontal direction with twelve variations by amplitude and period changes. Three different wave periods and four different wave amplitudes were used. The purpose was to alter natural convection motion in favor of heat transfer effectiveness. The main performance indicator was the base-plate average temperature. The independent geometric parameters were experimentally examined in terms of the effectiveness of natural convection heat transfer by the measured average temperature values. Heat transfer by radiation was calculated by an analytical algebraic approach in order to obtain the Nusselt number solely based on convective heat transfer. Eight different heat inputs were used for each tested geometry to change the Grashof and Rayleigh numbers in a laminar flow interval. As reference geometries, a flat plate and a heat sink with straight/flat-plate fins were utilized. The heat sinks were also oriented to three different angles by a test stand. Accordingly, thirty six unique experimental cases were examined as a result of 327 trials and 1100 hours of testing. It was realized that the wavy fin geometry enhances natural convection heat transfer compared to the base-plate and flat-plate-fin heat sinks. However, increasing period and amplitude of the wave form more than initial values deteriorated the gains by the modifications on the fins. Since a single-period, 2-mm-amplitude heat sink resulted in the highest Nusselt number for all orientations, an optimum may be sought about this setting. As a general evaluation, computational simulations for spatial resolution of the event physics and dimensional optimization are standing as future study targets.

A functional contextual, observer-centric, quantum mechanical, and neuro-symbolic approach to solving the alignment problem of artificial general intelligence: safe AI through intersecting computational psychological neuroscience and LLM architecture for emergent theory of mind.

There have been impressive advancements in the field of natural language processing (NLP) in recent years, largely driven by innovations in the development of transformer-based large language models (LLM) that utilize "attention." This approach employs masked self-attention to establish (via similarly) different positions of tokens (words) within an inputted sequence of tokens to compute the most appropriate response based on its training corpus. However, there is speculation as to whether this approach alone can be scaled up to develop emergent artificial general intelligence (AGI), and whether it can address the alignment of AGI values with human values (called the alignment problem). Some researchers exploring the alignment problem highlight three aspects that AGI (or AI) requires to help resolve this problem: (1) an interpretable values specification; (2) a utility function; and (3) a dynamic contextual account of behavior. Here, a neurosymbolic model is proposed to help resolve these issues of human value alignment in AI, which expands on the transformer-based model for NLP to incorporate symbolic reasoning that may allow AGI to incorporate perspective-taking reasoning (i.e., resolving the need for a dynamic contextual account of behavior through deictics) as defined by a multilevel evolutionary and neurobiological framework into a functional contextual post-Skinnerian model of human language called "Neurobiological and Natural Selection Relational Frame Theory" (N-Frame). It is argued that this approach may also help establish a comprehensible value scheme, a utility function by expanding the expected utility equation of behavioral economics to consider functional contextualism, and even an observer (or witness) centric model for consciousness. Evolution theory, subjective quantum mechanics, and neuroscience are further aimed to help explain consciousness, and possible implementation within an LLM through correspondence to an interface as suggested by N-Frame. This argument is supported by the computational level of hypergraphs, relational density clusters, a conscious quantum level defined by QBism, and real-world applied level (human user feedback). It is argued that this approach could enable AI to achieve consciousness and develop deictic perspective-taking abilities, thereby attaining human-level self-awareness, empathy, and compassion toward others. Importantly, this consciousness hypothesis can be directly tested with a significance of approximately 5-sigma significance (with a 1 in 3.5 million probability that any identified AI-conscious observations in the form of a collapsed wave form are due to chance factors) through double-slit intent-type experimentation and visualization procedures for derived perspective-taking relational frames. Ultimately, this could provide a solution to the alignment problem and contribute to the emergence of a theory of mind (ToM) within AI.

Viscoelastic vapor bubble collapse near solid walls and corresponding shock wave formation

This study investigates the influence of viscoelasticity on the collapse of aspherical vapor bubbles near a solid boundary through numerical simulations. A fully compressible three-dimensional finite volume method is employed, incorporating a single-fluid homogeneous mixture cavitation model and the simplified linear Phan-Thien Tanner viscoelastic constitutive model. The collapse dynamics, liquid jetting, shock wave formation, and associated pressure impact are analyzed, and the viscous and viscoelastic stress fields are presented. A comparison of viscoelastic to Newtonian dynamics reveals significant differences in collapse behavior and shock wave formation due to viscoelasticity. Viscoelasticity can induce jet piercing, which is not observed in the Newtonian collapse, and increases vapor re-evaporation after the first collapse. The effect of changing the initial standoff distance is examined for both viscoelastic and Newtonian fluids, where a second jet formation is present only for the viscoelastic collapse, and the second collapse's intensity is increased due to increased vapor production during rebound. Additionally, the variation of elasticity in the viscoelastic case demonstrates a correlation between the amount of vapor produced during rebound and the relaxation time for the investigated cases.

Numerical investigation of the underwater explosion of a cylindrical explosive with the Eulerian finite-element method

The shock wave and bubble dynamics of an underwater explosion are significant in various fields. When the charge is non-spherical, the detonation process will remarkably affect the shock wave formation and the subsequent bubble motion. In this work, the underwater explosion of a cylindrical explosive is investigated numerically with the Eulerian finite-element method combined with the programed burn model treating the detonation process. The present model is validated by comparing the simulated results with the experimental ones. Then, several cases with different slenderness of the explosive charge in various buoyancy environments are simulated and analyzed. The results demonstrate a notable variation of the shock wave in different directions. The shock wave will reach the highest pressure peak and shortest pulse width at a certain angle determined by the ratio between the speeds of the detonation wave and the shock wave. Furthermore, the non-spherical initial expansion of the bubble casts a significant influence on the subsequent bubble evolution. Three typical jet morphologies are identified with different combinations of buoyancy parameter and oblateness ratios of the bubble, featured by a slightly oblique upward jet penetrating the bubble, a laminar jet that failed to penetrate the bubble continuously, and a pair of opposite horizontal jets penetrating the bubble. Meanwhile, the horizontal jets that happen under a weak buoyancy environment will reduce the upward migration.

On the absence of shock waves and vacuum birefringence in Born–Infeld electrodynamics

We study the interaction of two counter–propagating electromagnetic waves in vacuum in the Born–Infeld electrodynamics. First we investigate the Born case for linearly polarized beams, E · B = 0, i.e., G2=0 (crossed field configuration), which is identical for Born–Infeld and Born electrodynamics; subsequently we study the general Born–Infeld case for beams which are nonlinearly polarized, G2≠0. In both cases, we show that the nonlinear field equations decouple using self-similar solutions and investigate the shock wave formation. We show that the only nonlinear solutions are exceptional traveling wave solutions which propagate with constant speed and which do not turn into shocks for our approximation. We obtain two types of exceptional wave solutions, then we numerically analyze which phase velocities correspond to the counter- or co-propagating beams and subsequently we determine the direction of propagation of the exceptional waves.