Attach an online PDE-constrained reconstruction layer to a neural operator instead of accepting its raw output field. The layer stays close to the network prediction at sampled output locations while minimizing a differentiable PDE residual and boundary-condition violation, allowing physics correction for each new input without retraining the neural operator.
Replace the usual isotropic Gaussian random Fourier features with a frequency distribution matched to the expected spectral regularity of the target function. For coordinate fields, operator-learning maps, or PDE solution surrogates, this should place more features where the target Fourier energy lies and improve approximation at the same feature count. Stabilize the resulting feature matrix with whitening or ridge regression because spectral accuracy can create severe ill-conditioning.
Replace fixed random Fourier features in a coordinate network or PINN with a small complex Fourier dictionary whose propagation directions are learned from a weighted residual. Given directions, solve the linear feature coefficients exactly or by ridge regression, and optimize only the directions in the outer loop. This should represent low-directional-complexity fields with fewer features and avoid wasting gradient updates on coefficients that can be fitted analytically.
For bandlimited or progressively higher-frequency targets, construct a nested random Fourier layer whose frequency window grows according to the paper's bandwidth laws instead of sampling all frequencies from one fixed range. Train with a low-bandwidth subset first, then activate additional frequency blocks. This creates a mathematically motivated spectral curriculum and may reduce early optimization difficulty while preserving high-frequency accuracy.
Augment a neural field or neural operator with a bank of localized, divergence-free moving packets whose radius and amplitude follow the Hill scaling rather than ordinary Gaussian scaling. The packet coefficients can represent unresolved flow corrections while keeping their L^2 contribution approximately invariant under refinement, preventing fine-scale features from becoming numerically negligible or explosively large.
Couple the number of operator training pairs to the output resolution instead of increasing the output grid independently. Refine the output discretization only while the oracle reconstruction improves, and increase the training set when the learned predictor remains substantially worse than the oracle decoder.
For a neural ODE or physics-informed neural network whose residual cancellation is reliable only after temporal averaging, add an analytic temporal corrector that integrates the zero-mean part of the residual over each time cell. The corrector vanishes at cell boundaries and is smaller by a factor of the cell duration, so it improves pointwise-in-time residuals without changing the learned state at synchronization times.
Prepend an adaptive Savitzky-Golay derivative bank to a temporal neural network. For each input channel and derivative order, select the local window by minimizing Stein's unbiased risk estimate, then concatenate the raw signal with the estimated derivatives. This supplies denoised velocity and acceleration features without requiring clean derivative targets or forcing the backbone to learn unstable finite-difference filters.