Wave Experiments Research Articles

Singlet-doublet fermionic dark matter in gauge theory of baryons

We are considering a minimal U(1)B extension of the Standard Model (SM) by promoting the baryon number as a local gauge symmetry to accommodate a stable dark matter (DM) candidate. The gauge theory of baryons induces non-trivial triangle gauge anomalies, and we provide a simple anomaly-free solution by adding three exotic fermions. A scalar S spontaneously breaks the U(1)B symmetry, leaving behind a discrete Z2 symmetry that ensures the stability of the lightest exotic fermion originally introduced to cancel the triangle gauge anomalies. Scenarios with weakly interacting DM candidates having non-zero hypercharge usually face stringent constraints from experimental bounds on the DM spin-independent direct-detection (SIDD) cross-section. In this work, we consider a two-component singlet-doublet fermionic dark matter scenario, which significantly relaxes the constraints from bounds on the DM SIDD cross-section for suppressed single-doublet mixing. We show that the model offers a viable parameter space for a cosmologically consistent DM candidate that can be probed through direct detection searches, collider experiments, and gravitational wave (GW) experiments.

Gravitational helicity flux density from two-body systems

Abstract The helicity flux density is a novel quantity which characterizes the angle-dependence of the helicity of radiative gravitons and it may be tested by gravitational wave experiments in the future. We derive a quadrupole formula for the helicity flux density due to gravitational radiation in the slow motion and the weak field limit. We apply the formula to the bound and unbound orbits in two-body systems and find that the total radiative helicity fluxes are always zero. However, the radiative helicity flux density, which is O ( G 3 ) in the Newtonian limit, still has non-trivial dependence on the angle. Furthermore, we also find a formula for the total helicity flux by including all contributions of the higher multipoles.

Penerapan Pembelajaran Seni Berbasis Steam: Studi Kasus Pembelajaran Musik Di TK Kemala Bhayangkari 34 Kendal

This study aims to analyze the concept and practice of STEAM-based art education (Science, Technology, Engineering, Arts, and Mathematics) at TK Kemala Bhayangkari 34 Kendal. The main focus of this research is to explore how the concept of art education, specifically music, is implemented within the STEAM framework at this school, as well as to examine how the practice is carried out by the teachers. The research employs a descriptive qualitative method with a case study approach, utilizing observation, interviews, and document analysis. The findings reveal that the teachers at TK Kemala Bhayangkari 34 Kendal have a strong understanding of the STEAM concept and successfully integrate its elements into music education. The lessons include sound wave experiments, creating musical instruments from recycled materials, and the use of digital music applications to introduce technology. Despite challenges related to limited resources and varying student abilities, the STEAM-based learning practice at this school has successfully created an engaging learning experience that enhances creativity, collaboration, and problem-solving skills. This study also shows that STEAM-based learning is highly relevant for early childhood education as it helps children connect various disciplines in a fun and practical way. Based on these findings, it is recommended that the STEAM approach be further implemented in early childhood education to support the holistic development of students.

Simulation and experiment of explosion shock wave in semi-closed environment

Simulation and experiment of explosion shock wave in semi-closed environment

Observation of coexistence of low and high frequency oscillations with reduced neutral density in a linear plasma device.

Abstract A linear plasma device has been developed at IASST producing uniform and quiescent (δne/ne < 0.5%) laboratory plasma for performing basic wave and instability experiments in a precise manner. Uniform plasma produced in the device is very quiescent (δne/ne < 0.5%) in nature in a wide neutral pressure range of ~ (3 − 6) × 10−4 mbar. However, beyond this neutral pressure range, onset of plasma instabilities leads to increase density fluctuations, thereby raising the value of δne/ne and reducing the degree of plasma quiescence. Recorded floating potential fluctuations with an array of Langmuir probes indicate the coexistence of low and high frequency oscillations at lower neutral pressure range. The nature of these plasma instabilities appear to be similar to those observed in the plume mode of hollow cathode discharges. A linear plasma device will facilitate the investigation of these self-excited oscillations in a controlled environment.

High Frequency Gravitational Wave bounds from galactic neutron stars

High-Frequency Gravitational Waves (HFGWs) constitute a unique window on the early Universe as well as exotic astrophysical objects. While the current gravitational wave experiments are more dedicated to the low frequency regime, the graviton conversion into photons in a strong magnetic field constitutes a powerful tool to probe HFGWs. In this paper, we show that neutron stars, due to their extreme magnetic field, are a perfect laboratory to study the conversion of HFGWs into photons. Using realistic models for the galactic neutron star population, we calculate for the first time the expected photon flux induced by the conversion of an isotropic stochastic gravitational wave background in the magnetosphere of the ensemble of neutron stars present in the Milky Way. We compare this photon flux to the observed one from several telescopes and derive upper limits on the stochastic gravitational wave background in the frequency range 108 Hz–1025 Hz. We find our limits to be competitive in the frequency range 108 Hz–1012 Hz.

Probing the neutrino seesaw scale with gravitational waves

Neutrinos are the most elusive particles of the Standard Model. The physics behind their masses remains unknown and requires introducing new particles and interactions. An elegant solution to this problem is provided by the seesaw mechanism. Typically considered at a high scale, it is potentially testable in gravitational wave experiments by searching for a spectrum from cosmic strings, which offers a rather generic signature across many high-scale seesaw models. Here we consider the possibility of a low-scale seesaw mechanism at the PeV scale, generating neutrino masses within the framework of a model with gauged U(1) lepton number. In this case, the gravitational wave signal at high frequencies arises from a first order phase transition in the early Universe, whereas at low frequencies it is generated by domain wall annihilation, leading to a double-peaked structure in the gravitational wave spectrum. The signals discussed here can be searched for in upcoming experiments, including gravitational wave interferometers, pulsar timing arrays, and astrometry observations. Published by the American Physical Society 2024

Physical experiments of waves generated by submerged steam eruptions with applications to volcanic tsunamis.

The tsunamigenic potential of underwater volcanic eruptions is not well understood, even though eruption-generated tsunamis can be devastating. To address how erupted steam bursts from underwater volcanoes generate tsunamis, we present the experiments, using pressurized steam injected vertically into a water tank. Results over various eruption conditions identify three eruption regimes, namely, shallow-, intermediate-, and deep-water eruptions, according to the combined effects of water depths, source strengths, and source durations. The transition between shallow and intermediate eruptions is characterized by critical depths maximizing tsunami wave heights, while the transition between intermediate and deep eruptions is characterized by containment depths inhibiting surface disturbances. Water depth and source intensity are the dominant factors controlling maximum wave amplitudes, more so than aspects of jet duration and condensation. These experiments and supporting dimensional analysis improve our understanding of how underwater volcanic eruptions form tsunamis, while also providing a complete dataset for advancing tsunami generation models.

A Paramagnetic Nickel-Zinc Hydride Complex.

Reaction of a molecular zinc-hydride [{(ArNCMe)2CH}ZnH] (Ar=2,6-di-isopropylphenyl) with 0.5 equiv. of [Ni(CO)Cp]2 led to the isolation of a nickel-zinc hydride complex containing a bridging 3-centre,2-electron Ni-H-Zn interaction. This species has been characterized in the solid-state by single crystal X-ray diffraction. DFT calculations are consistent with its formulation as a σ-complex derived from coordination of the zinc-hydride to a paramagnetic nickel(I) fragment. Continuous-wave and pulse EPR experiments suggest that this species is labile in solution. Further experiments show that in the presence of catalytic quantities of nickel(I) precursors, zinc-hydride bonds can undergo either H/D-exchange with D2 or dehydrocoupling to form Zn-Zn bonds. In combination, the data support the activation and functionalisation of zinc-hydride bonds at nickel(I) centres.

A Paramagnetic Nickel–Zinc Hydride Complex

AbstractReaction of a molecular zinc–hydride [{(ArNCMe)2CH}ZnH] (Ar=2,6‐di‐isopropylphenyl) with 0.5 equiv. of [Ni(CO)Cp]2 led to the isolation of a nickel–zinc hydride complex containing a bridging 3‐centre,2‐electron Ni−H−Zn interaction. This species has been characterized in the solid‐state by single crystal X‐ray diffraction. DFT calculations are consistent with its formulation as a σ‐complex derived from coordination of the zinc–hydride to a paramagnetic nickel(I) fragment. Continuous‐wave and pulse EPR experiments suggest that this species is labile in solution. Further experiments show that in the presence of catalytic quantities of nickel(I) precursors, zinc–hydride bonds can undergo either H/D‐exchange with D2 or dehydrocoupling to form Zn−Zn bonds. In combination, the data support the activation and functionalisation of zinc–hydride bonds at nickel(I) centres.

Hydrodynamic optimization and performance verification of fairings for round-ended cofferdams using dam-break wave experiments and numerical simulations

Round-ended cofferdams are crucial for large-scale marine projects but are vulnerable to the complex marine environment, including waves, tides, and storms. Enhancing the hydrodynamic performance of these cofferdams is essential for improving safety and efficiency in marine construction. This study introduces a novel fairing design aimed at reducing water flow resistance during the quasi-stable stage of a tsunami. The flow field is analyzed using computational fluid dynamics (CFD) simulations, and an adaptive surrogate model is employed to optimize the parameterized fairing shape. The results demonstrate that the optimized shape significantly suppresses vortex shedding, leading to a 16.59 % reduction in the drag coefficient and a 44.3 % reduction in the lift coefficient under flow conditions. Experimental and numerical simulations of dam-break waves are conducted for two designs, R1 and R0. By comparing their flow field and force characteristics, it is found that R1 effectively separates waves during the impulse stage, reduces wave climb height, and decreases impact loads. In the quasi-stable stage, R1 mitigates the blockage effect, reducing the liquid level difference between the front and back, and thus lowering flow forces. Experimental data further reveals that when the downstream is a dry riverbed, R1′s load reduction is particularly notable, with maximum reductions of 45.62 % in the impulse stage and 28.75 % in the quasi-stable stage. When the riverbed is wet, the maximum load reduction rates are 18.04 % and 8.72 %, respectively. Therefore, R1 not only reduces the resistance of round-end cofferdams under water currents but also under extreme wave forces, providing valuable insights for advancing ocean engineering design.

Centre for immersive wave experimentation

The “Centre for Immersive Wave Experimentation” (CIWE), located at “Innovation Park Zürich,” spans 200 m² and was designed to conduct ground-breaking research in the fields of acoustic and elastic wave propagation. In CIWE, we pioneer a novel approach to wave experimentation using immersive boundary conditions, seamlessly integrating the physical laboratory and a desired numerical domain. A cornerstone of CIWE is an advanced system of Field Programmable Gate Arrays (FPGAs), allowing the simultaneous acquisition and driving of 800 input and 800 output channels. This enables real-time interaction between a physical domain (e.g., the 40 m3 water pool or the 2.25 m2 2-D waveguide in CIWE) and arbitrary virtual domains. Recent pioneering experiments in CIWE have demonstrated cloning and cloaking of acoustic scattering objects. Elastic wave experiments benefit from a robotized 3-D laser Doppler vibrometer providing high-resolution velocity vector measurements. The ability to conduct non-contact measurements facilitates research in the areas of metamaterials and small-scale modelling in real-world proxies like sand and clay. Here, such measurements provide ground truth, verifying and complimenting numerical simulations. Furthermore, CIWE also facilitates innovation in the area of non-destructive testing, developing ultrasound full-waveform inversion techniques for precise structural health monitoring of laminated composites.

The quest for Dark Matter

Abstract This paper briefly presents the dark matter problem and the many ongoing attempts to solve it. After a brief introduction to the history of dark matter, the paper reviews the relevance of this mysterious component of the Universe in modern cosmology and it discusses the implications of the absence of evidence for dark matter in all experiments carried out in the past four decades. It then argues that a new era has started in the search for dark matter with much astronomical data about to become available and a new generation of gravitational wave experiments about to start operations. Finally, it stresses that the field of dark matter searches is completely open and that there are exciting opportunities for the next generation of scientists to develop new ideas and to make ground-breaking discoveries.

Response Patterns of Acoustic Wave Characteristics to Reservoir Petrophysical Parameters in Different Bedding Directions: A Case Study of Low- and Middle-Rank Coals in Xinjiang, China.

The physical properties of coal reservoirs, important parameters for evaluating the production potential of coalbed methane (CBM) resources, can be assessed nondestructively and in real-time using acoustic wave technology. In this study, we collected 48 low- and middle-rank coal samples oriented in different bedding directions from seven typical coal mines, encompassing the Zhunan, Tuha, and Kuqa-Bay coalfields in Xinjiang, China. We clarified the characteristics of the physical parameters (apparent density, fracture, porosity, and permeability) and acoustic wave of coal variations through acoustic wave, porosity, and permeability experiments, revealing the response law of acoustic wave characteristics to the physical parameters of coal. The results indicated that the acoustic wave velocity and dynamic elastic modulus (E d) of coal samples oriented in the perpendicular bedding direction are larger than those oriented in the parallel bedding direction; however, the dynamic Poisson's ratio (μd) of coal samples oriented in different bedding directions does not significantly differ. The existence of fractures significantly reduces the acoustic wave velocity and E d of the coal. The greater the apparent density of coal, the tighter its structure, resulting in a faster acoustic wave velocity. The larger the porosity of coal, the greater its internal voids, leading to a more pronounced attenuation of acoustic energy and a slower acoustic wave velocity. The more developed and interconnected the bedding fractures of coal bodies oriented in the parallel bedding direction, the higher their permeability, resulting in a smaller decrease in acoustic wave velocity. Conversely, the more developed the bedding fractures of coal bodies oriented in the perpendicular bedding direction, the more pronounced their attenuation of acoustic wave velocity. Finally, the regression equations for E d with the square of P-wave velocity (V P 2) and μd with the square ratio of V P to S-wave velocity (V P 2/V S 2) were established for coal. The study findings can help evaluate and predict the reservoir quality of coal seams, assess CBM, and improve the safety and efficiency of its extraction.

Dam-Break waves over mobile bed

Dam-break waves are a major concern for communities and infrastructures in flood-prone areas. The impact of dam-break waves against rigid obstacles after propagation on a mobile bed is lacking both in experimental datasets and in numerical investigations aimed at assessing the capabilities and limitations of available morphodynamic models. To fill these gaps, a novel data set from experiments of dam-break waves propagating over an erodible bottom and impacting over a vertical wall is presented and compared with numerical simulations performed by the Saint Venant–Exner model. First, the effects of bottom mobility are discussed by comparison with the corresponding fixed bed condition. Then, supplementary conditions are investigated for different initial water levels and reservoir lengths. The comparison with the results of the numerical simulation shows that the relatively simple model employed is able to reproduce the general features of the process and the peak impact force with reasonable accuracy.

Wave Pressure and Wave Height Distribution around Seawall Structure Constructed by an Array of TSP Circular Piles

An analytic solution for the interaction between an array of circular piles made by joining trapezoid steel pipes (TSP) and waves was obtained using an eigenfunction expansion method. First, an analytic model for the wave scattering of multiple piles fixed at arbitrary positions was derived, and then a simplified model was obtained assuming that an infinite array of identical piles were deployed perpendicular to the propagating direction of incident waves. A regular wave experiment was conducted using an experimental model with a scale ratio of 1/100 in a two-dimensional wave tank to verify the analytic solutions. The analytic results and experimental results were qualitatively consistent with each other. Using a developed analytic model, we examined the wave force on the multiple piles and the wave deformation in front of the arrayed piles. The period for the installation is greatly reduced as the TSP pile can be prefabricated in a factory. In particular, it is possible to install at the soft seabed. A seawall structure using arrayed TSP piles will be an ideal complement for a concrete seawall in future.

Trajectory tracking control of unmanned surface vehicle based on optimized barrier Lyapunov function under real ocean wave modeling

The state-constrained trajectory tracking control problem of unmanned surface vehicle (USV) under real wave interference is studied in this paper. This method is closer to the actual situation. Firstly, the interference of real ocean waves measured by ocean wave experiments on USV is considered. The wave spectrum and the equal interval method are used to simulate ocean waves in combination with the classical long-crested wave model. Secondly, the simulated wave is innovatively transformed into wave interference force, and the interference of the real wave is applied to the state constraint control of USV. The disturbance observer is used to observe and compensate for the external real wave interference, and the input saturation problem in real situations is fully considered. Furthermore, this paper proposes an improved logarithmic constraint function, which pre-set the performance function to constrain the trajectory tracking position error of the USV within a reasonable range. Finally, the rationality and effectiveness of the control strategy are verified by simulation.

Deep learning-based general beam synthesis for atmospheric propagation.

Optimizing the transmit light beams unlocks the full potential of free-space optical systems. However, designing application-specific light beams remains a challenge, especially for those traversing random media. In this study, we address this gap by proposing a deep learning-based method to generate optimal beams for propagation through atmospheric turbulence. The key mechanism is approximating the receiver statistics through batch-wise computation during the training of a convolutional neural network (CNN). On that basis, statistical performance metrics including average received power, scintillation index, and mean signal-to-noise ratio (SNR) are considered for optimization. Pseudo-modes of the beam are synthesized by weighted superposition of Hermite-Gaussian eigenmodes, enabling the creation of arbitrary complex amplitude profiles, i.e., general beams. An end-to-end implementation framework is designed to facilitate self-supervised learning and eliminate the need for pre-calculated datasets. Effectiveness of the synthesized beam is validated by wave optics simulation and experiments. In particular, comparison with Gaussian Schell-model beams demonstrates that the synthesized beam can achieve lower scintillation and greater intensity at the same time, leading to markedly enhanced receiver SNR. This advantage persists in a wider range of link configurations, extending the application range of stochastic beams.

Dark matter phenomenology and phase transition dynamics of the next-to-minimal composite Higgs model with a dilaton

In this paper, we conduct a comprehensive study of the next-to-minimal composite Higgs model (NMCHM) extended with a dilaton field χ (denoted as NMCHMχ). A pseudo-Nambu-Goldstone boson (pNGB) η, resulting from the SO(6)→SO(5) breaking, serves as a dark matter (DM) candidate. The inclusion of the dilaton field is helpful for evading the stringent constraints from dark matter direct detection, as it allows for an accidental cancellation between the amplitudes of DM-nucleon scattering, an outcome of the mixing between the dilaton and Higgs fields. The presence of the dilaton field also enriches the phase transition patterns in the early universe. We identify two types of phase transitions: (i) a 1-step phase transition, where the chiral symmetry and electroweak symmetry breaking (EWSB) occur simultaneously, and (ii) a 2-step phase transition, where the chiral symmetry breaking transition takes place first, followed by a second phase transition corresponding to EWSB. Since the first-order phase transitions can be strong due to supercooling in our model, we also examine the stochastic background of gravitational waves generated by these phase transitions. We find that these gravitational waves hold promise for detection in future space-based gravitational wave experiments, such as LISA, Taiji, BBO, and DECIGO. Published by the American Physical Society 2024

Nonlinear spatial evolution of degenerate quartets of water waves

In this manuscript we investigate the Benjamin–Feir (or modulation) instability for the spatial evolution of water waves from the perspective of the discrete, spatial Zakharov equation, which captures cubically nonlinear and resonant wave interactions in deep water without restrictions on spectral bandwidth. Spatial evolution, with measurements at discrete locations, is pertinent for laboratory hydrodynamic experiments, such as in wave flumes, which rely on time-series measurements at fixed gauges installed along the facility. This setting is likewise appropriate for experiments in electromagnetic and plasma waves. Through a reformulation of the problem for a degenerate quartet, we bring to bear techniques of phase-plane analysis which elucidate the full dynamics without recourse to linear stability analysis. In particular we find hitherto unexplored breather solutions and discuss the optimal transfer of energy from carrier to sidebands. We show that the maximal energy transfer consistently occurs for smaller side-band separation than the fastest linear growth rate. Finally, we discuss the observability of such discrete solutions in light of numerical simulations.