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1 | | -# Week 12 Summary: Uncertainty-aware regression & Gaussian Processes |
| 1 | +# Week 12 Summary: Physics-informed and constrained ML |
2 | 2 |
|
3 | 3 | ## Cross-Book Summary |
4 | 4 |
|
5 | | -### 1. Knowing what you don't know |
6 | | -- **Aleatoric vs. Epistemic:** Inherent physical noise vs. model ignorance. |
7 | | -- **Overconfidence Danger:** Point estimates fail safely in unknown regimes; uncertainty metrics are crucial. |
| 5 | +### 1. Physics-Informed Neural Networks (PINNs) |
| 6 | +- **Embedding Laws:** Enforce ODEs/PDEs via the loss function for physical consistency. |
| 7 | +- **Automatic Differentiation:** Exact derivative calculations enable NNs to evaluate physical equations. |
| 8 | +- **Boundary Conditions:** Methods like Lagaris substitution guarantee boundary compliance. |
8 | 9 |
|
9 | | -### 2. Gaussian Processes (GPs) |
10 | | -- **Distribution over Functions:** GP yields posterior mean and variance (uncertainty). |
11 | | -- **Kernels as Physical Priors:** Encodes assumptions about data smoothness/scale. |
12 | | -- **Non-Parametric Nature:** Scales with data size, ideal for small, high-quality materials datasets. |
| 10 | +### 2. Governing Equation Discovery |
| 11 | +- **Dictionary-Based Regression:** Build a dictionary of candidate math functions. |
| 12 | +- **Sparse Identification:** Use regularized regression (Lasso) to discover physical laws from noisy data. |
| 13 | +- **Dimensional Reasoning:** Unit analysis ensures physically plausible discoveries. |
13 | 14 |
|
14 | | -### 3. GP-Based Process Maps |
15 | | -- **Confidence Ribbons:** Visualize reliability to guide further experiments. |
16 | | -- **Kriging:** Interpolates materials property surfaces using GP regression. |
| 15 | +### 3. Constraints in Materials Science |
| 16 | +- **Monotonicity:** Enforce required physical trends (e.g., hardness vs. alloying). |
| 17 | +- **Hybrid Modeling:** Combine physical "White-Box" models with data-driven "Black-Boxes" (Grey-Box). |
17 | 18 |
|
18 | 19 | ## 90-Minute Lecture Strategy |
19 | 20 |
|
20 | | -### Part 1: Uncertainty in Science |
21 | | -- Risk management in materials processing. |
22 | | -- Visualizing distributions and error bars. |
| 21 | +### Part 1: Why Physics Matters |
| 22 | +- Limits of unconstrained Black-Box models. |
| 23 | +- Accurate but Physical models. |
| 24 | +- PINNs need less data. |
23 | 25 |
|
24 | | -### Part 2: GP Fundamentals |
25 | | -- Function vs. Parameter space. |
26 | | -- Kernels and "Similarity". |
27 | | -- Conditional Gaussians and Variance. |
| 26 | +### Part 2: Automatic Differentiation |
| 27 | +- GradientTape mechanics. |
| 28 | +- Derivatives as ML architecture components. |
28 | 29 |
|
29 | | -### Part 3: GP Case Studies |
30 | | -- Predicting tensile strength across parameters. |
31 | | -- GP for Experimental Design. |
32 | | -- Multi-Task GPs. |
| 30 | +### Part 3: Solving Physics with NNs |
| 31 | +- PINN Architectures: Data Loss + Physics Loss. |
| 32 | +- Enforcing Boundary Conditions. |
| 33 | +- 3D printing heat transfer case study. |
33 | 34 |
|
34 | | -### Part 4: Advanced Probabilistic ML |
35 | | -- Mixture Density Networks (MDNs). |
36 | | -- Dropout as Bayesian approximation. |
| 35 | +### Part 4: Equation Discovery |
| 36 | +- Sparse Regression and candidate dictionaries. |
| 37 | +- Damped pendulum equation case study. |
| 38 | +- Unit Analysis search pruning. |
37 | 39 |
|
38 | | -### Part 5: Decision Making |
39 | | -- Safe process windows via confidence intervals. |
40 | | -- Building trustworthy models. |
| 40 | +### Part 5: The Grey-Box Future |
| 41 | +- Hybrid architectures vs. FEA. |
| 42 | +- Building industrial trust. |
41 | 43 |
|
42 | 44 | ## Quarto Website Update (Summary) |
43 | 45 | **Summary for ML-PC Week 12:** |
44 | | -- Introduces Probabilistic Machine Learning for uncertainty quantification. |
45 | | -- Differentiates aleatoric (noise) from epistemic (ignorance) uncertainty. |
46 | | -- Uses Gaussian Processes (GPs) for uncertainty-aware regression. |
47 | | -- Applies confidence intervals to map robust process windows. |
| 46 | +- Combines neural networks with physical laws via Physics-Informed ML. |
| 47 | +- Introduces PINNs and automatic differentiation. |
| 48 | +- Details Governing Equation Discovery using sparse regression. |
| 49 | +- Applies physical constraints to build data-efficient Grey-Box models. |
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