arXiv subjects

Marc Serra Garcia

Publications and source records attributed to Marc Serra Garcia.

4 recordsLinked to original sources

arXiv2026

Diatom frustules as naturally occurring resonant microarchitectures: revealing vibrational eigenmodes across pennate and centric species

Diatom frustules, the hierarchically structured, species-specific silica exoskeletons of diatom microalgae, are among Nature's most sophisticated examples of bottom-up self-assembly, exhibiting nanoscale porosity, multifunctional mechanical and optical properties, and a morphological diversity that spans nearly three orders of magnitude in size. Despite growing interest in their optical and static mechanical properties, the elastodynamic behaviour of frustules has remained largely unexplored. Here we report the first experimental detection and spatially resolved reconstruction of vibrational eigenmodes in diatom frustules, combining laser Doppler vibrometry with morphology-faithful finite-element models informed by scanning electron microscopy (SEM) and focused-ion-beam scanning electron microscopy (FIB-SEM). Two morphologically contrasting taxa were investigated as model systems: the pennate diatom Rhaphoneis amphiceros and the centric diatom Stictodiscus californicus var. nitida, spanning the two principal branches of diatom diversity. Four eigenmodes were identified for R. amphiceros in the 5.90-14.17 MHz range and three for S. californicus in the 9.96-17.62 MHz range; the simulations yield a complete modal landscape for each species, including modally split and nearly degenerate eigenmodes arising from deviations from ideal symmetry, and show quantitative agreement with the experimentally measured mode shapes and resonant frequencies. These results establish diatom frustules as a class of naturally occurring resonant microarchitectures, and open new avenues for their integration as bio-derived functional elements in nanomechanical and MEMS/NEMS applications.

physics.app-ph↗

arXiv2026

Ground-to-Cable Strain Transfer in Unburied DAS on Earth and the Moon

Distributed Acoustic Sensing (DAS) measures dynamic strain along a fiber-optic cable, offering a robust, densely-sampled alternative to traditional seismic sensors. To ensure good ground-to-cable coupling, cables are typically buried in a shallow trench. Unburied surface deployments are attractive for rapid-response terrestrial applications as well as extraterrestrial missions, such as on the Moon, where burial is impractical. However, unburied DAS often suffers from severely degraded signal quality, due to poor strain transfer from ground to cable. The physical mechanism responsible remains unknown. Here, we identify bending stress relief as a mechanism that can explain this loss: suspended cable segments accommodate ground strain by bending rather than by stretching or compressing, reducing the measurable axial strain that reaches the fiber. We develop the first analytical and numerical model of unburied DAS coupling, representing the draped cable as a series of suspended segments between discrete ground contact points, to explain and quantify the bending stress relief mechanism. Our analysis reveals a dimensionless parameter, Theta, set by the ratio of the cable's initial gravity-induced sag to its radius, which governs the strain transfer efficiency. Once a segment's sag exceeds a quarter of the cable's radius, ground displacement starts to be absorbed by bending rather than being transferred as measurable axial strain. This framework predicts how mechanical properties, cable dimensions, pretension, and gravity affect strain transfer efficiency and provides quantitative guidelines for optimizing cable design and deployment strategies on both Earth and the Moon.

physics.geo-ph↗

arXiv2025

Mass-Spring Models for Passive Keyword Spotting: A Springtronics Approach

Mechanical systems played a foundational role in computing history, and have regained interest due to their unique properties, such as low damping and the ability to process mechanical signals without transduction. However, recent efforts have primarily focused on elementary computations, implemented in systems based on pre-defined reservoirs, or in periodic systems such as arrays of buckling beams. Here, we numerically demonstrate a passive mechanical system -- in the form of a nonlinear mass-spring model -- that tackles a real-world benchmark for keyword spotting in speech signals. The model is organized in a hierarchical architecture combining feature extraction and continuous-time convolution, with each individual stage tailored to the physics of the considered mass-spring systems. For each step in the computation, a subsystem is designed by combining a small set of low-order polynomial potentials. These potentials act as fundamental components that interconnect a network of masses. In analogy to electronic circuit design, where complex functional circuits are constructed by combining basic components into hierarchical designs, we refer to this framework as springtronics. We introduce springtronic systems with hundreds of degrees of freedom, achieving speech classification accuracy comparable to existing sub-mW electronic systems.

cs.SD↗

arXiv2024

Differences between quantum and classical adiabatic evolution

Adiabatic evolution is an emergent design principle for time modulated metamaterials, often inspired by insights from topological quantum computing such as braiding operations. However, the pursuit of classical adiabatic metamaterials is rooted in the assumption that classical and quantum adiabatic evolution are equivalent. We show that this is only true in the limit where the frequencies of all the bands are at infinite distance from $0$; and some instances of quantum adiabatic evolution, such as those containing zero modes, cannot be reproduced in classical systems. This is because mode coupling is fundamentally different in classical mechanics. We derive classical conditions to ensure adiabaticity and demonstrate that only under these conditions - which are different from quantum adiabatic conditions -, the single band Berry phase and Wilczek-Zee matrix for everywhere degenerate bands emerge as meaningful quantities encoding the geometry of classical adiabatic evolution. Finally, for general multiband systems we uncover a correction term in the non-Abelian gauge potential for classical systems.

cond-mat.mes-hall↗