Wave Configuration Research Articles

Role of atmospheric resonance and land–atmosphere feedbacks as a precursor to the June 2021 Pacific Northwest Heat Dome event

We demonstrate an indirect, rather than direct, role of quasi-resonant amplification of planetary waves in a summer weather extreme. We find that there was an interplay between a persistent, amplified large-scale atmospheric circulation state and soil moisture feedbacks as a precursor for the June 2021 Pacific Northwest "Heat Dome" event. An extended resonant planetary wave configuration prior to the event created an antecedent soil moisture deficit that amplified lower atmospheric warming through strong nonlinear soil moisture feedbacks, favoring this unprecedented heat event.

Dynamic Behaviors and Analytical Solutions of the Damped (2+1)‐Dimensional Nonlinear Schrödinger Equation

In this paper, abundant analytical solutions of the damped (2 + 1)‐dimensional nonlinear Schrödinger equation are achieved by taking advantage of the extended systematic method. By considering various values of parameters, dynamic behaviors of bright, dark soliton, period wave, and kink solitary solutions are displayed with different amplitudes and directions in 3D graphs, lines, contour maps, and time evolution plots. Further analysis of the obtained results is studied to show the efficient effect of the parameters on the propagation and configuration of waves. In addition, computer simulations are considered to show the correlation between parameters and velocity. Our results indicate that the extended systematic method for solving differential equations is more convenient and yields richer solutions. The other mathematical physics equations that appear in nonlinear science can also be investigated by the concept of this study.

Method of calculation of satellite flow parameters behind the point of Mach reflection

A mathematical model for the calculation and express analysis of triple configurations of air shock waves arising from an “elevated” explosion of a condensed high-energy material is presented. The considered blast waves with a long duration of the positive phase (compression phase) can take place in industrial and agricultural applications: in the explosion of fuel-air mixtures, explosive dust in elevators and granaries, as well as high-energy materials for agricultural and industrial applications based on ammonium nitrate and explosive saltpetre mixtures with petroleum products. The developed mathematical model uses exact and semi-empirical relationships developed earlier in the theory of optimal shock wave systems.

Research of an oblique detonation wave in a limited area

This work presents the results of two-dimensional numerical simulation of processes, arising from the interaction of an incoming flow of a well-mixed stoichiometric hydrogen-air mixture with a wedge in a bounded region at high Mach velocities using Navier-Stokes type equations taking into account chemical interactions. The Mach number of the incoming flow from 9 to 12 were considered. Various wave configurations were obtained depending on the velocity of the incoming flow. For the flow Mach number of 9, the presence of a detonation wave perpendicular to the flow was obtained. For high flow velocities, another similar wave configuration of the same type was obtained.

Extreme Relations of the Dynamical Pressures Downstream the Stationary Mach Configurations of Running Shock Waves

Extreme Relations of the Dynamical Pressures Downstream the Stationary Mach Configurations of Running Shock Waves

Analysis of soliton solutions with different wave configurations to the fractional coupled nonlinear Schrödinger equations and applications

Analysis of soliton solutions with different wave configurations to the fractional coupled nonlinear Schrödinger equations and applications

Exact solution for capillary waves on the surface of a liquid of finite depth

Using the Schwartz function method, we have obtained a new exact solution for the problem of stationary capillary waves of finite amplitude on the surface of a liquid that has a finite depth. The reliability of the solution was confirmed by the results of numerical verification of the main boundary equation. The obtained solution of the problem is general in the sense that for any Weber number one can find the corresponding wave configuration. Parametric analysis showed a nonmonotonic dependence of the wave-length and its amplitude on the Weber number. The fact that the problem has one more branch of the solution (the trivial solution) indicates the possibility of the existence of other branches. The Schwartz function method cannot guarantee finding all solutions of the problem even from the specified class of functions. Therefore, the question of reproducing the known exact solution of W. Kimmersley for this problem and its reliability remains open. Note that for the parameter ß included in the main boundary equation, W. Kimmersley preliminarily laid down assumption ß = 1. The found exact solution has the property that ß > 1 and cannot coincide with W. Kimmersley’s solution.

Joint IRS Location and Size Optimization in Multi-IRS Aided Two-Way Full-Duplex Communication Systems

Intelligent reflecting surfaces (IRSs) have emerged as a promising wireless technology for the dynamic configuration and control of electromagnetic waves, thus creating a smart (programmable) radio environment. In this context, we study a multi-IRS assisted two-way communication system consisting of two users that employ full-duplex (FD) technology. More specifically, we deal with the joint IRS location and size (i.e., the number of reflecting elements) optimization in order to minimize an upper bound of system outage probability under various constraints: minimum and maximum number of reflecting elements per IRS, maximum number of installed IRSs, maximum total number of reflecting elements (implicit bound on the signaling overhead) as well as maximum total IRS installation cost. First, the problem is formulated as a discrete optimization problem and, then, a theoretical proof of its NP-hardness is given. Moreover, we provide a lower bound on the optimum value by solving a linear-programming relaxation (LPR) problem. Subsequently, we design two polynomial-time algorithms, a deterministic greedy algorithm and a randomized approximation algorithm, based on the LPR solution. The former is a heuristic method that always computes a feasible solution for which (a posteriori) performance guarantee can be provided. The latter achieves an approximate solution, using randomized rounding, with provable (a priori) probabilistic guarantees on the performance. Furthermore, extensive numerical simulations demonstrate the superiority of the proposed algorithms compared to the baseline schemes. Finally, useful conclusions regarding the comparison between FD and conventional half-duplex (HD) systems are also drawn.

Shock wave configuration in a transonic flow through a mid-section of a last stage turbine blade cascade equipped with a part-span connector

This paper deals with the study of a flow field and namely the configuration of shock waves in a blade cascade equipped with a part-span connector called tie-boss. The cascade consists of prismatic blades formed from the mid-section of a very long last-stage blade of a steam turbine. The study is based on numerical simulations of the flow through a cascade that was previously tested in a wind tunnel. Commercial software Ansys CFX was used for the simulations and Ansys ICEM for the mesh generation. The computational domain contains non-homogenous mesh interfaces. The simulations showed that the presence of the tie-boss has a profound effect on the configuration of the shock waves. The blade exit shock waves are disturbed and new lateral shock waves are introduced into the flow.

Harten-Lax-van Leer-discontinuities with elastic waves (HLLD-e) approximate Riemann solver for two-dimensional elastic-plastic flows with slip/no-slip interface boundary conditions

We present a multi-material Harten-Lax-van Leer-discontinuities with elastic waves (HLLD-e) approximate Riemann solver with a hypoelastic model for solving two-dimensional elastic-plastic flows under tangential slip/no-slip interface boundary conditions. Shear waves and their effects have not been fully explored in HLL-type (Harten, Lax, and van Leer) Riemann solvers. To this end, transformed equations corresponding to the deviatoric stress and their Rankine–Hugoniot (RH) relations are obtained. In addition, normal interface and slip/no-slip boundary conditions are imposed separately to close the solver system. Associated with the modified ghost fluid method (MGFM), the propagation and configurations of the shear waves are examined, and the results agree with those of previous studies. In addition, rarefaction waves and fluid-structure interactions can be computed owing to the wide applicability of this solver. In the future, to better describe the behavior of plastic waves, elastoplastic results can be considered for an approximate Riemann solver.

Computational and Experimental Modeling in Magnetoplasma Aerodynamics and High-Speed Gas and Plasma Flows (A Review)

This paper provides an overview of modern research on magnetoplasma methods of influencing gas-dynamic and plasma flows. The main physical mechanisms that control the interaction of plasma discharges with gaseous moving media are indicated. The ways of organizing pulsed energy input, characteristic of plasma aerodynamics, are briefly described: linearly stabilized discharge, magnetoplasma compressor, capillary discharge, laser-microwave action, electron beam action, nanosecond surface barrier discharges, pulsed spark discharges, and nanosecond optical discharges. A description of the physical mechanism of heating the gas-plasma flow at high values of electric fields, which are realized in high-current and nanosecond (ultrafast heating) electric discharges, is performed. Methods for magnetoplasma control of the configuration and gas-dynamic characteristics of shock waves arising in front of promising and advanced aircraft (AA) are described. Approaches to the control of quasi-stationary separated flows, laminar–turbulent transitions, and static and dynamic separation of the boundary layer (for large PA angles of attack) are presented.

Revisiting Loré's retrograde thyroidectomy from the perspective of preserving the external branch of the superior laryngeal nerve.

Injury to the external branches of the superior laryngeal nerve (EBSLN) is the main reported cause of inexplicable post-thyroidectomy dysphonia (PTD) without recurrent laryngeal nerve (RLN) injury. Loré proposed a retrograde thyroidectomy (RT) technique in which the superior pole is dissected as a final step after the Berry ligament division, making this approach advantageous for protecting the EBSLN. However, evidence of this protective effect remains insufficient. We aimed to evaluate EBSLN function following RT and conventional thyroidectomy (CT) using postoperative electromyography (EMG). This is a retrospective cohort study conducted at a single tertiary center. Consecutive patients who had undergone CT or RT were included. Bilateral EMG of the cricothyroid muscle was performed 2-3 months postoperatively in all patients. Patient characteristics, postoperative findings of bleeding events, drain amount, hypocalcemia, calcium replacement, RLN function, and EBSLN function were thoroughly reviewed and compared between the two surgical approaches. Abnormalities in the EMG findings were reported based on the wave configuration, and the results were graded into four categories. Seven hundred and thirty-one consecutive patients who underwent CT (n=341), or RT (n=390) were included, and a total of 1,179 RLNs and EBSLNs were at risk in CT (n=601) and RT (n=578). The CT and RT groups had similar clinical characteristics and surgical data. Two groups presented similar postoperative results for bleeding incidence, drain amount, and hypocalcemia. All RLNs were identified in both groups and their permanent function was preserved. EBSLN was significantly less frequently identified in the surgical field during RT than it was during CT (0.3% vs. 4.2%, respectively; P<0.001). Abnormal rates of postoperative EMG on the EBSLN were significantly lower in the RT group than in the CT group (1.7% vs. 7.8%, respectively; P<0.001), while the CT group presented with a higher grade of abnormal EMG (P<0.001). The RT technique may be beneficial for preserving EBSLN function. Meticulous capsular dissection and appropriate traction of the upper pole facilitated by RT are crucial for decreasing the risk of EBSLN injury, which can be achieved without directly identifying the nerve.

Experimental study of the motion of a shock wave in the plasma of a pulsed volume discharge in air

The motion of quasi-plane shock waves with Mach numbers = 2.20–3.50 in the plasma of a nanosecond combined volume discharge in air at an initial pressure of 10–100 Torr has been experimentally studied on the basis of high-speed shadow registration of the flow field. The dynamics of shock–wave configurations after the discharge at various stages of an unsteady supersonic flow, which is formed after the diffraction of a plane shock wave by a rectangular obstacle, is studied. An increase in the velocity of the shock wave front over a time interval of up to 15 𝜇s in a plasma region of 9–40 mm long and its dependence on the plasma parameters is found. An analysis of relaxation processes in plasma showed that the acceleration of the shock wave front can be caused by air heating due to the quenching of electronically excited nitrogen molecules, in which the internal energy is converted into thermal energy at times up to 30 𝜇s.

Study on initiation characteristics of oblique detonation induced by hydrogen jets in acetylene-air mixtures

In this paper, effects of hydrogen jets in acetylene-air mixtures on the initiation characteristics of oblique detonation wave (ODW) are investigated, the two-dimensional (2D) multi-component NS equations considering detailed chemical reactions are solved. Influences of the transverse jet on flow field characteristics of the ODW are studied, including the initiation characteristics, the wave structures, and the state parameters. The existence of the jet changes the ignited mode of the ODW from double Mach interaction to single Mach interaction. Several wave configurations and their transitions induced by the jets are observed, including deflagration-to-detonation transition (DDT), jet-induced bow shock wave (BSW) in front of the transverse jet and rapidly develops into ODW, and ODW that generated directly in front of the transverse jet. The structure of these three wave systems is mainly influenced by the flow discharge of the hydrogen jet. When the hydrogen jet is small, no combustion is induced by the BSW in front of the jet. ODW is induced by the action of the deflagration wave and OSW. Increasing the hydrogen jet, BSW induces combustion and rapidly develops into ODW. When the hydrogen jet is large enough, the BSW disappears and direct detonation combustion occurs to produce ODW. Two types of relationships are obtained between the initiated position and the position of the transverse jet: the U-shaped curve at low flow discharge and the positive correlation at high flow discharge. When the flow discharge is small and no shock wave-induced combustion occurs, the initiated position is influenced by the position of the deflagration wave interacting with the OSW, which forms a U-shaped curve with the position of hydrogen jet. When the flow discharge is high and shock wave induced combustion occurs, ODW is rapidly developed behind the jet, resulting in a positive correlation between the initiated position and the position of hydrogen jet. Furthermore, the viscous effect has significant influence on the flow field characteristics of ODW, it promotes the transition between these initiation modes and shortens the initiation distance of oblique detonation. The findings of this study can better help understand the effect of transverse hydrogen jets on ODW initiation and contribute to theoretical studies and engineering applications of oblique detonation engines.

혼잡한 도심지 네트워크 환경에서 Flexible WLAN을 사용한 안정적인 WAVE 구축 연구

In this paper, we propose flexible WLAN as a solution for signal congestion and interference problems that directly affect IEEE 802.11 wireless communications in WAVE configurations for V2X in autonomous vehicles in urban congested network environments. The system uses the following RSSI detection from the vehicle to apply a variable decision algorithm. By changing the AP output based on this, we showed a 19.88% increase in stability and accuracy compared to the existing WAVE. We also confirmed that the fixed communication range in V2X-based urban environments can be replaced with a variable range in response to the environment to help build a stable communication environment with low interference and low latency in V2X environments.

Evaluation of wave configurations in corrugated boards by experimental analysis (EA) and finite element modeling (FEM): the role of the micro-wave in packaging design

The aim of this paper is to study the mechanical behavior of corrugated board boxes, focusing attention on the strength that the boxes are able to offer in compression under stacking conditions. A preliminary design of the corrugated cardboard structures starting from the definition of each individual layer, namely the outer liners and the innermost flute, was carried out. For this purpose, three distinct types of corrugated board structures that include flutes with different characteristics, namely the high wave (C), the medium wave (B), and even the micro-wave (E), were comparatively evaluated. More specifically, the comparison is able to show the potential of the micro-wave which would eventually allow a significant saving of cellulose in the fabrication process of the boxes, thus reducing the manufacturing costs and causing a lower environmental footprint. First, experimental tests were carried out to determine the mechanical properties of the different layers of the corrugated board structures. Tensile tests were performed on samples extracted from the paper reels used as base material for the manufacturing of the liners and flutes. Instead, the edge crush test (ECT) and box compression test (BCT) were directly performed on the corrugated cardboard structures. Secondly, a parametric finite element (FE) model to allow, on a comparative basis, the study of the mechanical response of the three different types of corrugated cardboard structures was developed. Lastly, a comparison between the available experimental results and the outputs of the FE model was carried out, with the same model being also adapted to evaluate additional structures where the E micro-wave was usefully combined with the B or C wave in a double-wave configuration.

Reflection and transition of planar curved shock waves

In this paper, the reflection of curved shock waves over a symmetry plane in planar supersonic flow is studied. This includes stable Mach reflection (MR) and the regular reflection (RR) to MR transition process. Curved shock theory (CST) is applied to derive the high-order parameters in front of and behind the shock wave. The method of curved shock characteristics is used to establish an analytical model to predict the wave configurations. The shock structures provided by the proposed model agree well with the numerical results. Flow structures, such as the height of the Mach stem and the shape of the shock wave and slip line, are studied by applying the analytical model. Isentropic waves generated from a curved wall are found to significantly influence the flow patterns. It appears that the compression waves obstruct the formation of the sonic throat and increase the Mach-stem height. The expansion waves have the opposite effect. The evolution mechanism of the Mach stem is found in conjunction with the RR-to-MR transition process. The CST is extended to a moving frame and used to model the transition. The time history of the moving triple point illustrates the effects of the incident shock angle and isentropic waves on the transition process.

Robust phase-controlled gates for scalable atomic quantum processors using optical standing waves

A simple scheme is presented for realizing robust optically controlled quantum gates for scalable atomic quantum processors by driving the qubits with optical standing waves. Atoms localized close to the antinodes of the standing wave can realize phase-controlled quantum operations that are potentially more than an order of magnitude less sensitive to the local optical phase and atomic motion than corresponding travelling wave configurations. The scheme is compatible with robust optimal control techniques and spatial qubit addressing in atomic arrays to realize phase controlled operations without the need for tight focusing and precise positioning of the control lasers. This will be particularly beneficial for quantum gates involving Doppler sensitive optical frequency transitions and provides an all optical route to scaling up atomic quantum processors.

High-efficiency silicon metasurface mirror on a sapphire substrate

For a possible implementation of high-efficiency Si-nanosphere metasurface mirrors functioning at telecom wavelengths in future gravitational wave detectors, exact dimensional and configuration parameters of the total system, including substrate and protective coating, have to be determined a priori. The reflectivity of such multi-layer metasurfaces with embedded Si nanoparticles and their potential limitations need to be investigated. Here we present the results on how the substrate and protective layer influence optical properties and demonstrate how dimensional and material characteristics of the structure alter light reflectivity. Additionally, we consider the impact of manufacturing imperfections, such as fluctuations of Si nanoparticle sizes and their exact placement, on the metasurface reflectivity. Finally, we demonstrate how high reflectivity of the system can be preserved under variations of the protective layer thickness, incident angle of light, and its polarization.

Numerical analysis and performance assessment of trapezoidal oscillating water columns

ABSTRACT Oscillating water column (OWC) device serve as a wave energy conversion tool in the on-shore and off-shore environment. This study encompasses the literature on OWC with single and multi-chambers for efficiency improvement. Geometrical configurations are modified from rectangular to trapezoidal in order to understand the fluid dynamics inside the OWC. The pressure drop and wave elevations are carefully matched and validated first and error limits are analysed. Further studies continue with the air pressure rise and fall inside the OWC and therefore the power-take off for the wave configurations is calculated. The dual OWC configuration separated by a wavelength distance offers the highest capture width ratio at all wave height and time periods. From the results, the capture width ratio is significant with the trapezoidal tandem configuration which is 9.96% increase with respect to a single-OWC configuration. A marginal increase of 2.87% is observed in trapezoidal case against rectangular shape in the context of tandem configuration.