State Wave Research Articles

Radiative losses and radiation-reaction effects at the first post-Newtonian order in Einstein–Cartan theory

Gravitational radiation-reaction phenomena occurring in the dynamics of inspiralling compact binary systems are investigated at the first post-Newtonian order beyond the quadrupole approximation in the context of Einstein–Cartan theory, where quantum spin effects are modeled via the Weyssenhoff fluid. We exploit balance equations for the energy and angular momentum to determine the binary orbital decay until the two bodies collide. Our framework deals with both quasi-elliptic and quasi-circular trajectories, which are then smoothly connected. Key observables like the laws of variation of the orbital phase and frequency characterizing the quasi-circular motion are derived analytically. We conclude our analysis with an estimation of the spin contributions at the merger, which are examined both in the time domain and the Fourier frequency space through the stationary wave approximation.

Research examining a spatial autocorrelation imaging method based on stationary characteristics of microtremors

The spatial autocorrelation method is an important method for extracting the velocity dispersion curve from microtremor data. However, site data typically cannot strictly meet spatial and temporal stationary feature, and this greatly affects the accuracy of the calculation results of this method. Therefore, based on the cosine similarity theory, this study deduces the applicability of the spatial autocorrelation method to unidirectional Rayleigh surface waves and again verifies the applicability of this method to spatially and temporally stationary Rayleigh waves. The numerical simulation results demonstrate that the velocity dispersion curve can be extracted from a one-way Rayleigh wave using the spatial autocorrelation method to obtain an accurate geological profile, whereas the superposition of finite groups of Rayleigh waves in different directions cannot yield an accurate geological profile. In this study, we quantitatively analyzed the impact of the spatial autocorrelation method on the extraction of the velocity dispersion curve when the signal could not meet the characteristics of temporal and spatial stationarity through numerical simulation. The results reveal that the velocity-dispersion curve can be accurately extracted only when the signal satisfies both spatial and temporal stationarity. When a signal is closer to the spatial and temporal stationary characteristics, this indicates that a more accurate velocity dispersion curve can be extracted. These results provide a reference for improving the calculation accuracy of spatial autocorrelation methods.

Polymorphic Kondo Effects Driven by Spin Lattice Coupling in VTe2

AbstractPolymorphism in transition metal dichalcogenides (TMDs) allows unique physical properties to be controlled, such as artificial heavy fermion phenomena, the quantum spin Hall effect, and optimized device operations with 2D materials. Besides lattice structural and metal‐semiconductor polymorphs, intriguing charge density wave (CDW) states with different electronic and magnetic phases are demonstrated in TMDs. Typically, the “normal” state is stabilized at high temperature above the CDW energy scale, and therefore, is not relevant to many low‐temperature quantum phenomena, such as magnetic ordering and the heavy fermion Kondo state. Here, a local and robust phase manipulation of the normal (1T) and CDW (1T’) states of VTe2 is reported by laser irradiation, and polymorphic Kondo effects are demonstrated with the two phases at low temperatures. The theoretical calculations show that Kondo screening of vanadium 3d electron moments is markedly enhanced in 1T’‐VTe2, which is responsible for the observed transport properties distinct from its 1T counterpart. Controlling the spin‐lattice coupling and Kondo physics via laser‐driven CDW phase patterning allows the design of correlated electronic and magnetic properties in TMDs.

First-principles investigation of transition of magnetic structures of ordered and disordered HfMnSb2 and TiMnSb2

Abstract We investigated the magnetic structure of HfMnSb2 and TiMnSb2 with first-principles calculations. We assumed ordered and disordered crystal structures for both compounds and investigated the transition of the magnetic structure. We theoretically confirmed that the helical magnetic order is stable in HfMnSb2, while the conical magnetic order was observed experimentally. Additionally, assuming a chemically ordered crystal structure in TiMnSb2 stabilizes the antiferromagnetic order. However, when the degree of order gradually decreases, the system exhibits spin-spiral density wave states and finally attains ferromagnetic order when the degree of order is 0. This trend is consistent with the experimentally measured results. We also found that the distortion of the lattice constants in TiMnSb2 compared to that of HfMnSb2 also plays an important role for the ferromagnetic order.

Adaptive moving window technique for SPH simulation of stationary shock waves

A novel adaptive moving window (AMW) technique is developed for simulating stationary shock waves in a moving coordinate system associated with a simulation box. The velocity of this system is adjusted by an iterative feedback algorithm with the purpose of establishing a desirable position of shock front. Galilean transformations are iteratively used to maintain the shape of the flow profile. The moving coordinate system has advantages in simulation over a conventional coordinate system associated with the intact material at rest. In particular, a truly steady flow regime can be established in this moving window (MW). Comparative simulation using the smoothed particle hydrodynamics method to study shock propagation in copper confirms that the AMW converges to a steady state faster than a MW technique with a fixed velocity. We demonstrate that AMW can be applied for very weak shocks. Advantage of AMW is revealed in SPH simulation of the front structure for weak shocks in porous copper that result in a partial pore compaction. Specifically, we clarify the mechanism of the partial pore collapse for shock velocities below a knee on a calculated shock Hugoniot, where this knee corresponds to the complete collapse of pores.

Some new lump molecules and hybrid molecular states of a (3 + 1)-dimensional generalized variable coefficient Kadomtsev–Petviashvili equation

In this paper, a (3 + 1)-dimensional generalized variable coefficient Kadomtsev–Petviashvili equation is investigated systematically, which can characterize evolution of the long water waves and small amplitude surface waves with the weak nonlinearity, weak dispersion, and weak perturbation in fluid mechanics. We investigate one lump and lump molecules obtained from one breather and breather molecules by a new degenerating breather method, respectively. In addition, the bound state of lump molecules and other localized waves is derived theoretically by velocity resonance. Considering the condition of variable coefficient, the several sets of interesting solutions having a complex structure are obtained, which include the type of parabolic, S-shaped, and periodic. The analysis method can also help us to study lump molecules existing in other integrable systems from a new perspective.

Chiral Meta‐Coder for Spin Switchable Electromagnetic Camouflage and Information Authentication

AbstractElectromagnetic camouflage is crucial for concealing the physical identity of the object from external electromagnetic detection, whether in military operations or civilian contexts. However, addressing the pressing issue of seamlessly transitioning between camouflage and visualization capabilities is a significant challenge. By combining chiral meta‐atoms and irregular phase encoding method, a novel chiral meta‐coder is proposed for spin switchable electromagnetic camouflage and target authentication. Different from traditional conformal strategies, this meta‐coder achieves camouflage functionality by tightly arranging meta‐atoms around the target object and encoding suitable phase sequences to shape desired wavefront. Simultaneously, the target object can also be identified by modulating the helical state of the incident wave. As a proof of concept, a chiral meta‐coder operating in camouflaging “A” shaped target object is designed and experimentally demonstrated. When exposed to right circularly polarized waves, the meta‐atoms surrounding the object can adapt the wavefront to conceal target information. The camouflaged pattern exhibits diffuse scattering in the far field and three focal patterns around the near field. Conversely, these meta‐atoms transition into a wave‐absorbing configuration, facilitating the precise identification of target information. Such a strategy may find potential applications in data security, privacy, and communication.

Superconductivity in unconventional metals

Based on first-principles calculations, we demonstrate that 1H/2H-phase transition metal dichalcogenides MX2 (M = Nb, Ta; X = S, Se, Te) are unconventional metals, which have an empty-site band of A1′@1e\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${A}_{1}^{{\\prime} }@1e$$\\end{document} elementary band representation at the Fermi level. The computed phonon dispersions indicate the stability of the system at high temperatures, while the presence of the soft phonon mode suggests a phase transition to the charge density wave state at low temperatures. Based on the Bardeen-Cooper-Schrieffer theory and computed electron-phonon coupling, our calculations show that the superconductivity (SC) in NbSe2 is mainly attributed to the soft phonon mode due to the half filling of the empty-site band. Accordingly, the SC has been predicted in unconventional metals TaNS monolayer and 2H-TaN2 bulk with computed TC = 10 K and 26 K respectively. These results demonstrate that the unconventional metals with partial filling of the empty-site band offer an attractive platform to search for superconductors.

Visualization of Alternating Triangular Domains of Charge Density Waves in 2H-NbSe_{2} by Scanning Tunneling Microscopy.

The charge density wave (CDW) state of 2H-NbSe_{2} features commensurate domains separated by domain boundaries accompanied by phase slips known as discommensurations. We have unambiguously visualized the structure of CDW domains using a displacement-field measurement algorithm on a scanning tunneling microscopy image. Each CDW domain is delimited by three vertices and three edges of discommensurations and is designated by a triplet of integers whose sum identifies the types of commensurate structure. The observed structure is consistent with the alternating triangular tiling pattern predicted by a phenomenological Landau theory. The domain shape is affected by crystal defects and also by topological defects in the CDW phase factor. Our results provide a foundation for a complete understanding of the CDW state and its relation to the superconducting state.

Aquaplanet simulations with winter and summer hemispheres: model setup and circulation response to warming

Abstract. To support further understanding of circulation changes in a warming climate, an idealised aquaplanet model setup containing summer and winter hemispheres is presented, and the results of circulation changes under warming are discussed. First, a setup is introduced that enables aquaplanet simulations with a warmer and a colder hemisphere, including realistic-looking summer and winter jet streams, storm tracks, and precipitation patterns that are fairly similar to observations, as well as a more intense and equatorward storm track in the winter compared to the summer hemisphere. The sea surface temperature (SST) distribution used here is inspired by the June–July–August zonal mean SST found in reanalysis data and is flexible to allow control of the occurrence of a single or double intertropical convergence zone (ITCZ). The setup is then used to investigate circulation changes under uniform warming, as motivated by recent research. For example, the stronger poleward shift of the storm tracks during summer compared to winter is reproduced. Furthermore, the jet waviness decreases under warming when compared on isentropes with maximum wind speed or isentropes at similar heights in pressure space. Jet stream waviness increases under warming when compared at similar-valued isentropes but primarily because the corresponding isentrope is closer to the surface in the warmer climate and waviness climatologically increases downwards in the atmosphere. A detailed analysis of the changes in wave amplitude for different wavenumbers confirms that the amplitude of large waves increases with warming, while that of short waves decreases with warming. The reduction in wave amplitude of short synoptic waves is found to dominate in the jet core region, where jet waviness also decreases and is more pronounced on the equatorward side of the jet. Long waves increase in amplitude on the poleward side of the jet and at upper stratospheric levels, which is consistent with increased jet waviness at these levels. The projected increased amplitude of planetary waves and the reduced amplitude of synoptic waves are thus clear in our aquaplanet simulations and do not require zonal asymmetries or regional warming patterns. During so-called high-amplitude wave events, there is no evidence for a preferential phase of Rossby waves of wavenumbers 5 or 7, indicating the crucial role of stationary waves forced by orography or land–sea contrast in establishing previously reported preferential phases. We confirm that feature-based block detection requires significant tuning to the warmer climate to avoid the occurrence of spurious trends. After adjustment for changes in tropopause height, the block detection used here shows no trend in the summer hemisphere and an increase in blocking in the colder hemisphere. We also confirm previous findings that the number of surface cyclones tends to decrease globally under warming and that the cyclone lifetimes become shorter, except for very long-lived cyclones.

Quantum Resonance with the Mind: a Comparative Analysis of Buddhism's Eighth Consciousness, Quantum Holography and Jung's Collective Unconscious

This interdisciplinary exploration discusses the intricate conceptual linkages among Buddhism’s Eighth State of Consciousness, Quantum Holography, and the Jungian Collective Unconscious. Central to this study is examining the Eighth Consciousness in Buddhist thought—a realm that transcends the conventional sensory and mental states to connect with a more universal and profound awareness. Drawing parallels, Quantum Holography posits that every part of the universe retains information about the whole, much like a hologram. This notion seemingly mirrors the Jungian concept of the Collective Unconscious, which postulates a shared reservoir of memories and ideas across humanity. The paper contends that the intricate dance of photons, oscillating between particle and wave states, mediates perception through resonance and hints at a multi-layered consciousness stratum that mirrors the vast, enigmatic quantum reality expanse. The study illuminates the intersections and divergences among these frameworks through meticulous comparative analysis, positing that an integrative understanding of quantum theories and Buddhist wisdom can unravel the human psyche’s profound depths. By weaving Eastern philosophies with the Western psychological and quantum theoretical tapestry, the discourse unveils a multifaceted consciousness comprehension, championing integrative approaches as invaluable tools for decoding the mind and universe's enigmatic interplay from a quantum viewpoint.

The free piston problem for pressureless Euler equations under the gravity

In this paper, the exact solutions of the free piston problem for the one-dimensional pressureless Euler equations under gravity are constructed in fully explicit forms. It is found that delta shock wave and vacuum state are contained in the solutions with appropriate initial condition. Furthermore, the trajectory function of the piston can be obtained in the combination of the generalized Rankine-Hugoniot conditions and Newton's second law, and it can be uniquely determined by the generalized entropy condition. We observe and analyze carefully some interesting nonlinear phenomena. For instance, delta shock wave absorbs the vacuum state and forms a new delta shock wave. In addition, some representative numerical simulations are presented to confirm the correctness of theoretical analysis.

The Dominant Role of the Summer Hemisphere in Subtropical Lower Stratospheric Wave Drag Trends

AbstractIt is well established that the shallow branch of the Brewer‐Dobson circulation accelerates in a warming climate due to enhanced wave drag in the subtropical lower stratosphere. This has been linked to the strengthening of the upper flanks of the subtropical jets. However, the seasonality of the zonal wind trends, peaking in the winter hemisphere, is opposite to that of the Eliassen‐Palm flux convergence trends, peaking in summer. We investigate the seasonality in the wave drag trends and find a different behavior for each hemisphere. The Shepherd and McLandress (2011, https://doi.org/10.1175/2010jas3608.1) mechanism, involving transient wave dissipation at higher levels following the rise of the critical lines, is found to maximize in austral summer. On the other hand, in the Northern Hemisphere the wave drag increase peaks in summer primarily due to the changes in the stationary planetary waves (monsoonal circulations) associated with enhanced deep convection.

Increased Asian aerosols drive a slowdown of Atlantic Meridional Overturning Circulation

Observational evidence and climate model experiments suggest a slowdown of the Atlantic Meridional Overturning Circulation (AMOC) since the mid-1990s. Increased greenhouse gases and the declined anthropogenic aerosols (AAs) over North America and Europe are believed to contribute to the AMOC slowdown. Asian AAs continue to increase but the associated impact has been unclear. Using ensembles of climate simulations, here we show that the radiative cooling resulting from increased Asian AAs drives an AMOC reduction. The increased AAs over Asia generate circumglobal stationary Rossby waves in the northern midlatitudes, which shift the westerly jet stream southward and weaken the subpolar North Atlantic westerlies. Consequently, reduced transport of cold air from North America hinders water mass transformation in the Labrador Sea and thus contributes to the AMOC slowdown. The link between increased Asian AAs and an AMOC slowdown is supported by different models with different configurations. Thus, reducing emissions of Asian AAs will not only lower local air pollution, but also help stabilize the AMOC.

Comparison of probabilistic forecasts of extreme precipitation for a global and convection‐permitting ensemble and hybrid statistical–dynamical method based on equatorial wave information

AbstractRecent work has demonstrated that skilful hybrid statistical–dynamical forecasts of heavy rainfall events in Southeast Asia can be made by combining model forecasts of the phases and amplitudes of Kelvin, Rossby, and westward‐moving Rossby gravity waves with climatological rainfall statistics conditioned on these waves. This study explores the sensitivity of this hybrid forecast to its parameter choices and compares its skill in forecasting extreme rainfall events in the Philippines, Malaysia, Indonesia, and Vietnam to that of the Met Office Global and Regional Ensemble Prediction System (MOGREPS). The hybrid forecast is found to outperform both the global and convection‐permitting ensemble in some regions when forecasting the most extreme events; however, for less extreme events, the ensemble is found more skilful. A weighted blend of the MOGREPS forecasts and the hybrid forecast was found to have the highest skill of all for almost all definitions of extreme event and in most regions. To quantify the influence of errors in the predicted wave state on the skill of the hybrid forecast, the skill of a hypothetical best‐case forecast was also calculated using reanalysis data to specify the wave amplitudes and phases. This best‐case forecast indicates that errors in the forecasts of all wave types reduce the skill of hybrid forecast; however, the reduction in skill is largest for Kelvin waves. The skill in convection‐permitting models is greater than for global models in the regions where Kelvin waves dominate, but the added value of limited‐area high‐resolution forecasts is hampered by the poor representation of Kelvin waves in the parent global model.

EFFICIENCY OPTIMIZATION OF OWC WAVE ENERGY CONVERTERS BY INCIDENT FLOW STEERING

In recent years, the interest in capturing wave energy has increased notably due to the immense potential available and the need to deepen and diversify the use of renewable energies. Oscillating Water Column (OWC) technology is one of the most technologically developed, with the world's first grid-connected demonstration plant located in Mutriku. However, the efficiency of this technology is still insufficient for its consolidation in the energy mix. Therefore, the present work presents an advance in the increase in the extraction of energy from the incident waves through the installation of a frontal ramp that directs the wave flow towards the vertical chamber of the oscillating column. The improvement achieved will be determined by means of a CFD (Computational Fluid Dynamics) 2D scaled model, which represents the interaction of the structure with different incident wave states. Different geometric options of the ramp are analyzed in comparison with the usual vertical wall option where the phenomenon of pure reflection occurs. This work aims to contribute to improving the efficiency of OWC technology, favoring the use of wave energy as a renewable energy source. Keywords: Oscillating Water Column (OWC), wave energy converter (WEC), Response Amplitude Operator (RAO), Computational Fluid Dynamics (CFD), wave energy

Numerical analysis of influencing factors on wave load for an amphibious aircraft

Numerical method of wave load for an amphibious aircraft is carried out in this paper, and its effectiveness is verified by comparing with towing tank model test. It shows that at the same wavelength and speed, the aircraft’s wave load is positively correlated with the change of wave height, but with the increase of wavelength, the difference shows a gradually decrease. And wave load is positively correlated with the speed, the greater the speed, the greater the wave load is. The wave load decreases with the increase of the wavelength. The peak load generally occurs in the short wave state of 1.2 times the length of the fuselage. With the increase of the wavelength, the aircraft load gradually decreases.

Simultaneous pseudospin and valley topological edge states of elastic waves in phononic crystals made of distorted Kekulé lattices

Topological metamaterials protected by the spatial inversion symmetry mainly support single type edge state, interpreted by either the quantum valley Hall effect or the quantum spin Hall effect. However, owing to the existence of the complicated couplings and waveform conversions during elastic wave propagation, realizing topologically protected edge states that support both pseudospin and valley degrees of freedom in elastic system remains a great challenge. Here, we propose a two-dimensional Kekulé phononic crystal (PC) that can simultaneously possess pseudospin- and valley-Hall edge states in different frequency bands. By inhomogeneously changing the elliptical direction in a Kekulé lattice of elliptical cylinders, three complete phononic bandgaps exhibiting distinct topological phase transitions can be obtained, one of which supports a pair of pseudospin-Hall edge states and the other hosts valley-Hall edge states in the low and high frequency regime. Furthermore, a sandwiched PC heterostructure and a four-channel cross-waveguide splitter are constructed to achieve selective excitation and topological robust propagation of pseudospin- and valley-momentum locking edge states in a single configuration. These results provide new possibilities for manipulating in-plane bulk elastic waves with both pseudospin and valley degrees of freedom in a single configuration, which has potential applications for multiband and multifunctional waveguiding.

Development of Interactive Multimedia Based on ISpring Suite Integrated Prompting Question to Facilitate Students' Concept Understanding Ability

The 21st century has been characterized by great advances in science and technology. These developments have efficiently addressed many issues in the field of education, in the study of physics. Effective physics learning focuses on students' concept understanding. However, the reality is that students' concept understanding is low, especially in the material of traveling waves and stationary waves. The proposed solution is to develop interactive multimedia based on iSpring suite integrated with prompting questions. The purpose of this interactive multimedia is to determine its characteristics and validity. The type of research used is development research using the Plomp development model. Initial data was collected using a four tier diagnostic test and analysis of 2 interactive multimedia journals. The validity test was conducted by 5 lecturers of Physics FMPA UNP. The validity analysis results reached 0.85 valid category.

Application of Judd–Ofelt theory in analyzing Dy: SrCaF4 single crystal

The optical properties of Dy:SrCaF4 crystal in the visible range are investigated. Judd-Ofelt intensity parameters are evaluated following the assignment of Stark levels of absorption bands. The absorption coefficient and absorption cross section are reported, together with the line strengths of several transitions from the ground state to excited state manifold, oscillator strength of the electric and magnetic dipoles moments (fed, fmd). The emission wavelength (λem), calculated fluorescence branching ratios (βR), radiative emission probabilities (AR), total radiative emission probability (Ar) and radiative lifetime (τR) of Dy3+ in CaSrF4 crystal are investigated for the transitions from energy levels 4F9/2 (474 nm), 4I15/2 (452 nm), 6P5/2 (364 nm) and 6P7/2 (348 nm) to related sublevels. Dy:CaSrF4 crystal is a promising gain medium for a continuous wave or tunable solid state visible micro-laser under the pump wavelength of 348 nm, 364 nm and 474 nm.