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arxiv: 2501.18355 · v2 · submitted 2025-01-30 · 📡 eess.AS · cs.SD· cs.SY· eess.SP· eess.SY

ML-ARIS: Multilayer Underwater Acoustic Reconfigurable Intelligent Surface with High-Resolution Reflection Control

Lina Pu , Yu Luo , Aijun Song This is my paper

Pith reviewed 2026-05-23 05:02 UTC · model grok-4.3

classification 📡 eess.AS cs.SDcs.SYeess.SPeess.SY
keywords multilayer acoustic RISpiezoelectric layerssynthetic reflectionunderwater communicationsbeam steeringreconfigurable intelligent surfacehigh-resolution reflectionpassive acoustic control
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The pith

A multilayer piezoelectric structure lets one acoustic reflector produce reflected waves with independently set high-resolution amplitudes and orthogonal phases.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The paper introduces an architecture that stacks multiple piezoelectric layers inside each reflector unit of an acoustic reconfigurable intelligent surface. Each layer connects to its own control circuit so that load impedance can be set separately. The combined output from the layers creates synthetic reflections whose amplitude and phase can be chosen with fine resolution. Tank experiments and simulations show that this combination is achievable in practice. The result would allow underwater sound to be steered toward chosen directions while limiting spillover elsewhere, all with a passive single-unit reflector.

Core claim

The ML-ARIS design places several layers of piezoelectric material in each reflector and allows independent adjustment of the load impedance on every layer through dedicated control circuits. This arrangement produces passive synthetic reflection, so that a single reflector unit can generate reflected acoustic waves whose amplitudes and phases are set at high resolution and made mutually orthogonal. Simulations and tank experiments confirm that the required impedance settings can be realized and that the resulting reflection patterns support directed beam steering.

What carries the argument

Multilayer piezoelectric reflector whose per-layer load impedances are adjusted independently to synthesize a desired reflection coefficient from their combined response.

If this is right

  • Sound energy can be steered precisely toward chosen underwater locations using only passive reflectors.
  • Unwanted acoustic interference outside the target direction is reduced by shaping the reflection pattern at each unit.
  • A single reflector replaces what would otherwise require an array of separate units to achieve comparable phase and amplitude granularity.
  • Energy consumption drops because the surface operates passively once the impedances are set.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • The same layered-impedance principle could be tested in air or in solid media where acoustic control is also needed.
  • Networks of such units might allow distributed shaping of underwater sound fields without central power sources at every reflector.
  • Increasing the number of layers per unit offers a direct route to finer phase steps if hardware permits independent control.

Load-bearing premise

The impedance on each piezoelectric layer can be controlled independently without mutual coupling or dissipation that would block the full set of target amplitudes and orthogonal phases.

What would settle it

A tank measurement in which the measured reflection coefficients from a multilayer unit fail to reach the full range of desired amplitudes at orthogonal phases even when the individual layer impedances are varied over their full available range.

Figures

Figures reproduced from arXiv: 2501.18355 by Aijun Song, Lina Pu, Yu Luo.

Figure 1
Figure 1. Figure 1: IQ modulation implemented with separated reflectors. [PITH_FULL_IMAGE:figures/full_fig_p003_1.png] view at source ↗
Figure 3
Figure 3. Figure 3: Control circuit of a two-layer acoustic reflector. [PITH_FULL_IMAGE:figures/full_fig_p004_3.png] view at source ↗
Figure 2
Figure 2. Figure 2: The structure of a multilayered acoustic reflector. [PITH_FULL_IMAGE:figures/full_fig_p004_2.png] view at source ↗
Figure 4
Figure 4. Figure 4: Impedance variation of PZT disk 1 with frequency and [PITH_FULL_IMAGE:figures/full_fig_p005_4.png] view at source ↗
Figure 6
Figure 6. Figure 6: Stress variation across 4 layers of the PZT stack, measured [PITH_FULL_IMAGE:figures/full_fig_p006_6.png] view at source ↗
Figure 5
Figure 5. Figure 5: Impedances of PZT layers under varying incident angles of [PITH_FULL_IMAGE:figures/full_fig_p006_5.png] view at source ↗
Figure 7
Figure 7. Figure 7: Electrical equivalent to a PZT disk. Let ZS be the equivalent impedance of the secondary winging, where ZS = RM + j(2πfLM − 1 2πfCM ) + Zrad. (5) Consequently, the total impedance of the PZT disk can be derived by ZR = RE 1 + (2πfCERE) 2 −j 2πfCER2 E 1 + (2πfCERE) 2 +ϕ 2ZS. (6) Near the resonance frequency, the inductive and capacitive reactances of Zp in (6) cancel out each other, thus only the resistance… view at source ↗
Figure 8
Figure 8. Figure 8: Architecture of the enhanced matching circuit. [PITH_FULL_IMAGE:figures/full_fig_p007_8.png] view at source ↗
Figure 9
Figure 9. Figure 9: Settings of tank tests. The reflectors consist of two PZT-4 disks separated by a polyethylene terephthalate (PET) film. The sound wave propagation speed in the disk is approximately 3900 m/s; each PZT disk measures ϕ 49.2 mm × 2.7 mm and resonates near 44 kHz. The matching network and load states of the reflectors are controlled by the circuit board shown in [PITH_FULL_IMAGE:figures/full_fig_p008_9.png] view at source ↗
Figure 12
Figure 12. Figure 12: Normalized amplitudes of reflected waves measured in [PITH_FULL_IMAGE:figures/full_fig_p010_12.png] view at source ↗
Figure 11
Figure 11. Figure 11: Phases of reflected waves measured in tank tests. [PITH_FULL_IMAGE:figures/full_fig_p010_11.png] view at source ↗
Figure 15
Figure 15. Figure 15: Reflected beams from an ML-ARIS of 8 reflectors. [PITH_FULL_IMAGE:figures/full_fig_p011_15.png] view at source ↗
Figure 13
Figure 13. Figure 13: Phases of reflected waves measured in simulations. [PITH_FULL_IMAGE:figures/full_fig_p011_13.png] view at source ↗
Figure 14
Figure 14. Figure 14: Normalized amplitudes of reflected waves measured in [PITH_FULL_IMAGE:figures/full_fig_p011_14.png] view at source ↗
Figure 16
Figure 16. Figure 16: Comparison of reflected beam generated by different [PITH_FULL_IMAGE:figures/full_fig_p012_16.png] view at source ↗
read the original abstract

This article introduces a multilayered acoustic reconfigurable intelligent surface (ML-ARIS) architecture designed for the next generation of underwater communications. ML-ARIS incorporates multiple layers of piezoelectric material in each acoustic reflector, with the load impedance of each layer independently adjustable via a control circuit. This design increases the flexibility in generating reflected signals with desired amplitudes and orthogonal phases, enabling passive synthetic reflection using a single acoustic reflector. Such a feature enables precise beam steering, enhancing sound levels in targeted directions while minimizing interference in surrounding environments. Extensive simulations and tank experiments were conducted to verify the feasibility of ML-ARIS. The experimental results indicate that implementing synthetic reflection with a multilayer structure is indeed practical in real-world scenarios, making it possible to use a single reflection unit to generate reflected waves with high-resolution amplitudes and phases.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

2 major / 1 minor

Summary. The paper introduces ML-ARIS, a multilayer piezoelectric acoustic reconfigurable intelligent surface in which each reflector unit contains multiple layers whose load impedances can be adjusted independently via control circuits. This architecture is claimed to enable passive synthetic reflection that produces reflected waves with high-resolution amplitudes and orthogonal phases from a single unit, thereby supporting precise beam steering. Feasibility is asserted on the basis of simulations and tank experiments.

Significance. If the hardware-level independent control can be realized without prohibitive coupling or dissipation, the approach would allow substantially finer phase/amplitude granularity per reflector than conventional single-layer RIS designs, with direct implications for underwater acoustic beamforming efficiency and interference management.

major comments (2)
  1. [Abstract] Abstract: the statement that 'the experimental results indicate that implementing synthetic reflection with a multilayer structure is indeed practical in real-world scenarios' supplies no quantitative metrics (measured amplitude/phase values, RMS error, coupling coefficients, or comparison against single-layer baselines), so the central feasibility claim cannot be evaluated.
  2. [Tank experiments (section describing hardware validation)] The weakest link in the central claim is the assumption that load impedances on each piezoelectric layer can be set independently to reach the desired orthogonal-phase/amplitude loci. No data on measured cross-layer coupling coefficients, parasitic dissipation, or deviation from ideal loci under simultaneous multi-layer control appear in the experimental description, leaving the hardware feasibility unverified.
minor comments (1)
  1. [Design / Methods] Provide explicit circuit diagrams or impedance-control equations showing how independent per-layer termination is implemented without violating passivity or introducing unmodeled mutual inductance.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for the constructive feedback on our manuscript. We address each major comment below and have revised the manuscript to strengthen the presentation of experimental results where the concerns are valid.

read point-by-point responses

  1. Referee: [Abstract] Abstract: the statement that 'the experimental results indicate that implementing synthetic reflection with a multilayer structure is indeed practical in real-world scenarios' supplies no quantitative metrics (measured amplitude/phase values, RMS error, coupling coefficients, or comparison against single-layer baselines), so the central feasibility claim cannot be evaluated.

    Authors: We agree that the abstract would be strengthened by including quantitative metrics. In the revised manuscript we have updated the abstract to report specific measured values from the tank experiments, including achieved amplitude and phase resolutions, RMS deviation from target loci, and direct comparison against single-layer baselines. These metrics are now cross-referenced to the experimental section. revision: yes

  2. Referee: [Tank experiments (section describing hardware validation)] The weakest link in the central claim is the assumption that load impedances on each piezoelectric layer can be set independently to reach the desired orthogonal-phase/amplitude loci. No data on measured cross-layer coupling coefficients, parasitic dissipation, or deviation from ideal loci under simultaneous multi-layer control appear in the experimental description, leaving the hardware feasibility unverified.

    Authors: The referee correctly notes the absence of explicit cross-layer characterization. Our original experiments measured end-to-end reflection performance under multi-layer control but did not separately report coupling coefficients or per-layer dissipation. We have added a new subsection to the experimental results that presents the measured coupling matrix, observed parasitic losses, and deviation statistics under simultaneous drive. These additions directly address the independent-control assumption while preserving the original performance claims. revision: yes

Circularity Check

0 steps flagged

No derivation chain or self-referential structure present; claim rests on external experiments.

full rationale

The manuscript introduces an ML-ARIS hardware architecture and reports that tank experiments and simulations confirm feasibility of independent per-layer impedance control for high-resolution passive reflection. No equations, fitted parameters, predictions derived from internal definitions, or self-citation chains appear in the abstract or described content. The central statement is an empirical claim verified against physical hardware rather than any reduction of outputs to inputs by construction. This is the normal case of a self-contained experimental paper.

Axiom & Free-Parameter Ledger

0 free parameters · 0 axioms · 0 invented entities

Abstract-only review supplies no explicit free parameters, axioms, or invented physical entities beyond the proposed design itself.

pith-pipeline@v0.9.0 · 5679 in / 1118 out tokens · 54176 ms · 2026-05-23T05:02:28.810630+00:00 · methodology

discussion (0)

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