Abstract In this article, a multifunctional and tunable radar absorber which can achieve dynamical modulation of absorbing frequency, bandwidth, amplitude is presented. Such composed graphene capacitor layer an active metasurface layer. By controlling the impedance characteristic each through external bias voltages, not only ultrawideband electromagnetic (EM) performance, but also be switched to narrowband absorption mode, its further adjusted at above operation modes. Both simulated...

The marine environment can be regarded as a fluid-solid coupled medium, with the upper layer being fluid medium and lower solid medium. Accurate simulation of seismic waves in is crucial for achieving accurate inversion multiple parameters. elastic wave equation viscoelastic ensemble method regard S-wave velocity domain zero, thus producing erroneous boundary conditions, resulting obvious numerical dispersion energy distortion simulated field at boundary. This has significant implications...

The spontaneous generation of near-inertial waves (NIWs) from quasi-geostrophic mesoscale eddies in a stratified fluid is investigated and the process mechanism clarified by numerical modeling theoretical analysis. Mesoscale eddies, as slow balance flows, are inevitably accompanied unbalanced oscillations (NIOs) their long period evolution. A eddy supplies kinetic energy to NIOs through its interaction with perturbations, which exist universally world oceans. Afterward, NIWs generated...

The varve chronological approach has been applied to older ages (pre-Quaternary) in the Shanwang Basin for first time. This study focuses on analysis of diatom shale from Basin, which was formed Maar Lake (a volcanic crater basin, often filled by a lake). lacustrine sediments basin encapsulate comprehensive geological information. By identifying species and providing systematic paleontological descriptions diatoms profile, two genera seven were recognized. A microscopic examination thin...

Typhoons, extratropical cyclones, and cold fronts cause strong winds leading to storm surges waves in the Bohai Sea. A wave–flow coupled numerical model is established for events observed 2022 caused by three weather systems, investigate how are modulated wave–tide–surge interaction (WTSI). Wave response basically controlled water level change coastal areas, where bottom friction or breaking dominates energy dissipation, determined current field deep altering whitecapping. height...

The emission of inertia-gravity waves (IGWs) from an exact geostrophic vortex in a rotating and stratified fluid is investigated by three-dimensional numerical modeling. An initially balanced inevitably generates IGWs with spiral patterns within short transient time period through instability mechanism. This result reinforces the nonexistence exactly invariant slow manifolds. direction rotation clockwise for both anticyclonic cyclonic vortices, which consistent theoretical prediction. Spiral...

Summary In summary, our work tackles challenges in traveltime inversion within the Automatic Differentiation (AD) framework. We introduce a smooth and differentiable soft-argmax-based loss function, addressing limitations of traditional hard argmax operations. Unlike conventional methods, approach utilizes weighted average probabilities, ensuring continuous outcome across distribution. Numerical examples affirm effectiveness this function an AD context, providing robust initial model for...

The energy transformation between inertial oscillations (IOs), near-inertial waves (NIWs), and mesoscale eddies during spontaneous NIW generation is analyzed by the kinetic equations of multiple temporal–spatial scale interaction slow fast motions then quantitatively estimated numerical simulations. evolution perturbed quasi-geostrophic accompanied IOs. nonlinear IOs results in transfer from to NIWs. However, act as catalysts process, because there no NIWs for longer than one period entirely...

Reverse time migration (RTM) is based on the two-way wave equation, so its imaging results obtained by conventional zero-lag cross-correlation conditions contain a lot of low-wavenumber noises. So far, wavefield decomposition method Poynting vector has been developed to suppress these noises; however, this also some problems, such as unstable calculation vector, low accuracy decomposition, and poor effect large-angle artifacts suppression. This article introduces optical flow RTM realize...

PreviousNext No AccessSEG Technical Program Expanded Abstracts 2002Tuning constrained first‐arrival tomographyAuthors: Baofu ChenZhenfei ZhaoBo ZhaoBaofu ChenZhongping Qian and Guangming Zhu, Zhenfei ZhaoZhongping Bo Zhuhttps://doi.org/10.1190/1.1817403 SectionsAboutPDF/ePub ToolsAdd to favoritesDownload CitationsTrack CitationsPermissions ShareFacebookTwitterLinked InReddit Permalink: https://doi.org/10.1190/1.1817403FiguresReferencesRelatedDetailsCited byA New First Break Pick-up Method...

A gradient preconditioning approach based on transmitted wave energy for least-squares reverse time migration (LSRTM) is proposed in this study. The preconditioned by using the of “approximate transmission wavefield,” which calculated non-reflecting acoustic equation. method can effectively avoid a huge amount calculation and storage required Hessian matrix or approximated overcome influence reflected waves, multiples, other wavefields seismic (GPSWE). numerical experiments, compared with...

High-resolution spaceborne synthetic aperture radar (SAR) images have verified the wide existence of internal solitary waves (ISWs) over Chukchi and Beaufort Seas. A major ISW generation hotspot has been observed at mouth Mackenzie River. Considering weak tidal currents relatively flat topography Shelf, such ISWs are unlikely to be generated by tide–topography interactions. However, this is more likely caused intrusion river plumes. Therefore, River plume investigated numerically. series...

Global changes have profound impacts on the structure and function of terrestrial ecosystems. It is a prerequisite to realize sustainable use ecosystem clarify response adaptation mechanism ecosystems global changes. Network control experiment an important way understand change factors at regional scales. The scientific top-level design conducive integration, comparison analysis integrative network-data, then supports development universal ecological theory. We comprehensively expounded...