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Related papers: Space-Time Graded-Index Interfaces and Related Chi…

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A corpus of recent work has revealed that the learned index can improve query performance while reducing the storage overhead. It potentially offers an opportunity to address the spatial query processing challenges caused by the surge in…

Databases · Computer Science 2021-02-16 Songnian Zhang , Suprio Ray , Rongxing Lu , Yandong Zheng

Transmission through reconfigurable intelligent surfaces (RISs), which control the reflection/scattering characteristics of incident waves in a deliberate manner to enhance the signal quality at the receiver, appears as a promising…

Information Theory · Computer Science 2020-01-30 Ertugrul Basar

We consider wave propagation through a 1D periodic network of slowly time-modulated interfaces. Each interface is modelled by time-dependent spring-mass jump conditions, where mass and rigidity interface parameters are modulated in time.…

Mathematical Physics · Physics 2026-03-31 Michaël Darche , Raphaël Assier , Sébastien Guenneau , Bruno Lombard , Marie Touboul

The miniaturisation of optical systems is an ongoing challenge across the electromagnetic spectrum. While the thickness of optical elements themselves can be reduced using advances in metamaterials, it is the voids between these elements --…

Applied Physics · Physics 2024-09-19 Michal Mrnka , Thomas Whittaker , David B. Phillips , Euan Hendry , Will Whittow

The usefulness of semiconductor lasers is often limited by the undesired frequency modulation, or chirp, a direct consequence of the intensity modulation and carrier dependence of the refractive index in the gain medium. In spin-lasers,…

Mesoscale and Nanoscale Physics · Physics 2012-03-22 Guilhem Boeris , Jeongsu Lee , Karel Vyborny , Igor Zutic

We show that ultrathin metasurfaces with a specific multiresonant response can enable simultaneously arbitrarily-strong and arbitrarily-broadband dispersion compensation, pulse (de-)chirping and compression or broadening. This breakthrough…

Optics · Physics 2023-04-11 Odysseas Tsilipakos , Thomas Koschny

Achieving generalizable and precise robotic manipulation across diverse environments remains a critical challenge, largely due to limitations in spatial perception. While prior imitation-learning approaches have made progress, their…

Robotics · Computer Science 2025-05-28 Yiqi Huang , Travis Davies , Jiahuan Yan , Jiankai Sun , Xiang Chen , Luhui Hu

In this paper, we present a new multi-antenna modulation scheme, termed as {\em space-time index modulation (STIM)}. In STIM, information bits are conveyed through antenna indexing in the spatial domain, slot indexing in the time domain,…

Information Theory · Computer Science 2016-09-27 Swaroop Jacob , T. Lakshmi Narasimhan , A. Chockalingam

Scattering wave systems that are periodically modulated in time offer many new degrees of freedom to control waves both in spatial and frequency domains. Such systems, albeit linear, do not conserve frequency and require the adaptation of…

Applied Physics · Physics 2023-04-25 Matthieu Malléjac , Romain Fleury

We provide a new hydrodynamic framework to describe out-of-equilibrium integrable systems with space-time inhomogeneous interactions. Our result builds up on the recently-introduced Generalized Hydrodynamics (GHD). The method allows to…

Statistical Mechanics · Physics 2019-09-30 Alvise Bastianello , Vincenzo Alba , Jean Sébastien Caux

According to Albert Einstein, gravitation is analogous to an optical medium. Building on this idea, various definitions of the gradient-index (GRIN) medium representing curved spacetime have been proposed; often, these approaches demand…

General Relativity and Quantum Cosmology · Physics 2025-06-13 J. E. Gómez-Correa , E. Espíndola-Ramos , O. López-Cruz , S. Chávez-Cerda

Chirp signals have established diverse applications caused by the capable of producing time-dependent linear frequencies. Most feature extraction transformation methods for chirp signals focus on enhancing the performance of transform…

Signal Processing · Electrical Eng. & Systems 2024-01-11 Shuyi Gu , Zhenghua Luo , Lin Hu , Yilin Zhang , Junxiong Guo

The second-order, small-scale dependence structure of a stochastic process defined in the space-time domain is key to prediction (or kriging). While great efforts have been dedicated to developing models for cases in which the spatial…

Methodology · Statistics 2020-10-01 Jun Tang , Dale Zimmerman

We propose a general method for designing wideband matching tapers in inhomogeneous media where phase velocity is coupled to the taper impedance profile. Such tapers are used to match wideband gradient index (GRIN) lens antennas. To…

Applied Physics · Physics 2022-01-26 Wei wang , Nicolas Garcia , Jonathan Chisum

The role of graded interfaces between materials in a cylindrical free-standing quantum wire with longitudinal heterostructures is theoretically investigated, by solving the Schr\"odinger equation within the effective mass approximation.…

Mesoscale and Nanoscale Physics · Physics 2011-05-06 Andrey Chaves , J. A. K. Freire , G. A. Farias

Autonomous driving is reshaping the way humans travel, with millimeter wave (mmWave) radar playing a crucial role in this transformation to enabe vehicle-to-everything (V2X). Although chirp is widely used in mmWave radar systems for its…

Signal Processing · Electrical Eng. & Systems 2025-05-23 Zhuoran Li , Shufeng Tan , Zhen Gao , Yi Tao , Zhonghuai Wu , Zhongxiang Li , Chun Hu , Dezhi Zheng

Phononic crystals and acoustic metamaterials are periodic structures whose effective properties can be tailored at will to achieve extreme control on wave propagation. Their refractive index is obtained from the homogenization of the…

Applied Physics · Physics 2019-03-05 Yabin Jin , Bahram Djafari-Rouhani , Daniel Torrent

The forced time harmonic response of a spatiotemporally-modulated elastic beam of finite length with light damping is derived using a novel Green's function approach. Closed-form solutions are found that highlight unique mode coupling…

Applied Physics · Physics 2024-09-05 Benjamin M. Goldsberry , Andrew N. Norris , Samuel P. Wallen , Michael R. Haberman

When an excited electromagnetically open optical waveguide goes through a temporal transition of its material properties, it radiates to the ambient surroundings. In this letter, we explore this radiation and reveal, using asymptotic…

Optics · Physics 2024-09-19 Amir Shlivinski , Yakir Hadad

Index modulation (IM) significantly enhances the spectral efficiency of fluid antennas (FAs) enabled multiple-input multiple-output (MIMO) systems, which is named FA-IM. However, due to the dense distribution of ports on the FA, the…

Information Theory · Computer Science 2024-08-20 Xinghao Guo , Yin Xu , Dazhi He , Cixiao Zhang , Wenjun Zhang , Yi-yan Wu