Parameter Optimization

Goal

Provide a workflow to design experiments, rank parameter influence, and select optimization strategies for materials simulation calibration.

Requirements

Python 3.8+
No external dependencies (uses Python standard library only)

Inputs to Gather

Before running any scripts, collect from the user:

Input	Description	Example
Parameter bounds	Min/max for each parameter with units	`kappa: [0.1, 10.0] W/mK`
Evaluation budget	Max number of simulations allowed	`50 runs`
Noise level	Stochasticity of simulation outputs	`low`, `medium`, `high`
Constraints	Feasibility rules or forbidden regions	`kappa + mobility < 5`

Decision Guidance

Choosing a DOE Method

Is dimension <= 3 AND full coverage needed?
├── YES → Use factorial
└── NO → Is sensitivity analysis the goal?
    ├── YES → Use quasi-random (preferred; "sobol" is accepted but deprecated)
    └── NO → Use lhs (Latin Hypercube)

Method	Best For	Avoid When
`lhs`	General exploration, moderate dimensions (3-20)	Need exact grid coverage
`sobol`	Sensitivity analysis, uniform coverage	Very high dimensions (>20)
`factorial`	Low dimension (<4), need all corners	High dimension (exponential growth)

Choosing an Optimizer

Is dimension <= 5 AND budget <= 100?
├── YES → Bayesian Optimization
└── NO → Is dimension <= 20?
    ├── YES → CMA-ES
    └── NO → Random Search with screening

Noise Level	Recommendation
Low	Gradient-based if derivatives available, else Bayesian Optimization
Medium	Bayesian Optimization with noise model
High	Evolutionary algorithms or robust Bayesian Optimization

Script Outputs (JSON Fields)

Script	Output Fields
`scripts/doe_generator.py`	`samples`, `method`, `coverage`
`scripts/optimizer_selector.py`	`recommended`, `expected_evals`, `notes`
`scripts/sensitivity_summary.py`	`ranking`, `notes`
`scripts/surrogate_builder.py`	`model_type`, `metrics`, `notes`

Workflow

Generate DOE with scripts/doe_generator.py
Run simulations at DOE sample points (user's responsibility)
Summarize sensitivity with scripts/sensitivity_summary.py
Choose optimizer using scripts/optimizer_selector.py
(Optional) Fit surrogate with scripts/surrogate_builder.py

CLI Examples

# Generate 20 LHS samples for 3 parameters
python3 scripts/doe_generator.py --params 3 --budget 20 --method lhs --json

# Rank parameters by sensitivity scores
python3 scripts/sensitivity_summary.py --scores 0.2,0.5,0.3 --names kappa,mobility,W --json

# Get optimizer recommendation for 3D problem with 50 eval budget
python3 scripts/optimizer_selector.py --dim 3 --budget 50 --noise low --json

# Build surrogate model from simulation data
python3 scripts/surrogate_builder.py --x 0,1,2 --y 10,12,15 --model rbf --json

Conversational Workflow Example

User: I need to calibrate thermal conductivity and diffusivity for my FEM simulation. I can run about 30 simulations.

Agent workflow:

Identify 2 parameters → --params 2
Budget is 30 → --budget 30

Use LHS for general exploration:

python3 scripts/doe_generator.py --params 2 --budget 30 --method lhs --json

After user runs simulations and provides outputs, summarize sensitivity:

python3 scripts/sensitivity_summary.py --scores 0.7,0.3 --names conductivity,diffusivity --json

Recommend optimizer:

python3 scripts/optimizer_selector.py --dim 2 --budget 30 --noise low --json

Error Handling

Error	Cause	Resolution
`params must be positive`	Zero or negative dimension	Ask user for valid parameter count
`budget must be positive`	Zero or negative budget	Ask user for realistic simulation budget
`method must be lhs, sobol, or factorial`	Invalid method	Use decision guidance to pick valid method
`scores must be comma-separated`	Malformed input	Reformat as `0.1,0.2,0.3`

Security

Input Validation

sensitivity_summary.py validates --names against [a-zA-Z_][a-zA-Z0-9_ .-]* with a 200-char limit, preventing shell metacharacter injection via crafted parameter names
All numeric list inputs are validated as finite numbers (NaN/Inf rejected)
Comma-separated value lists are capped (10,000 for scores, 100,000 for surrogate data) to prevent resource exhaustion
doe_generator.py caps dimension at 1,000 and budget at 1,000,000; optimizer_selector.py caps dimension at 100,000 and budget at 10,000,000
--method is validated against a fixed allowlist (lhs, sobol, factorial)
--noise is validated against a fixed allowlist (low, medium, high)
--model (surrogate type) is validated against a fixed allowlist (rbf, linear, polynomial)

File Access

Scripts read no external files; all inputs are provided via CLI arguments
Scripts write only to stdout (JSON output); no files are created unless the agent explicitly uses the Write tool

Tool Restrictions

Read: Used to inspect script source, references, and user data files
Write: Used to save DOE sample plans, sensitivity rankings, or optimizer recommendations; writes are scoped to the user's working directory
Grep/Glob: Used to locate relevant files and search references
The skill's allowed-tools excludes Bash to prevent the agent from executing arbitrary commands when processing user-provided parameter names and constraints

Safety Measures

No eval(), exec(), or dynamic code generation
All subprocess calls use explicit argument lists (no shell=True)
Reduced tool surface (no Bash) limits the agent to read/write operations only
Parameter names are sanitized before use, preventing injection via crafted identifiers

Limitations

Not for real-time optimization: Scripts provide recommendations, not live optimization loops
Surrogate is a placeholder: surrogate_builder.py computes basic metrics; replace with actual model for production
No automatic simulation execution: User must run simulations externally and provide results

References

references/doe_methods.md - Detailed DOE method comparison
references/optimizer_selection.md - Optimizer algorithm details
references/sensitivity_guidelines.md - Sensitivity analysis interpretation
references/surrogate_guidelines.md - Surrogate model selection

Version History

v1.1.0 (2024-12-24): Enhanced documentation, decision guidance, conversational examples
v1.0.0: Initial release with core scripts

parameter-optimization