# Instrument simulation challenges: plate (tier 1)

This repository defines simulation challenges for a thin, free, struck aluminum plate, and publishes the comparison of every registered solution at [challenges/plate/site](https://vault1.magland.org/challenges/plate/site/). It follows the same arrangement as the tier 0 repository [challenges/string](https://vault1.magland.org/challenges/string): the model is defined in the continuum, solutions live in separate registered repositories, and the shared [challenge-tools](https://vault1.magland.org/challenges/challenge-tools) package scores them against a reference chosen from among the submissions.

## Challenges

| ID | Title | Deliverable |
| --- | --- | --- |
| [plate-strike-v1](challenges/plate-strike-v1/README.md) | Struck free aluminum plate, radiated pressure by the Rayleigh integral | 3 s mono wav, 48 kHz, float32 |

The model is three-dimensional linear elastodynamics with Kelvin-Voigt and frequency-independent damping, on a 12 in by 12 in by 1.04 mm plate of aluminum 6061-T6, free on all faces, struck by a smooth force pulse. Thin-plate theories (Kirchhoff-Love, Mindlin-Reissner) are approximations to this model, and their error relative to a converged three-dimensional solution includes the modeling error of plate theory. Until such a solution is submitted, the reference is the best thin-plate solution and the reported errors measure only differences within plate theory; the results page says which it is.

Each challenge lives in `challenges/<challenge-id>/` and consists of a `README.md`, which is the authoritative specification, and a `challenge.json` with the parameters, output format, error measures, and the recommended grid for optional field exports in machine-readable form. A challenge is never changed once solutions exist for it; a corrected or modified model gets a new ID.

## Solution repositories and the registry

The repositories that take part in the comparison are listed in [registry/solution-repos.json](registry/solution-repos.json). To register one, open a pull request adding an entry (repository, branch, path of its `solutions` directory). A solution repository contains `solutions/<challenge-id>/<submission-id>.json` files following the [submission schema](https://vault1.magland.org/challenges/challenge-tools/blob/main/schema.json), with wav files beside them or at URLs, and optionally field exports (about 45 MB each for this challenge, so git LFS or an external URL is advisable). [challenges/plate-solutions](https://vault1.magland.org/challenges/plate-solutions) is the first one and serves as an example.

The comparison workflow clones every registered repository at the head of its branch and runs on any push to this repository or when dispatched by hand (`mochi workflow run .mochi/workflows/results.yml --repo challenges/plate`). Nothing in the vault triggers across repositories, so a push to a solution repository is picked up at the next run here.

## Scoring

Every solution is compared with the reference under the two error measures defined in the challenge README, the relative waveform and spectrogram errors; the waveform error ranks. The reference is chosen automatically from the accuracy orderings that submissions assert about their own solutions, by the rule described in the [string repository README](https://vault1.magland.org/challenges/string/blob/main/README.md#how-solutions-are-scored) and implemented in challenge-tools, with the same limitations. A challenge may override the choice by naming a solution in `reference_solution` in its `challenge.json`; this will be the natural thing to do once a verified three-dimensional solution exists.