| Type: | Package |
| Title: | Physics-Informed Neural Networks for Progressive Censoring |
| Version: | 0.1.0 |
| Description: | Implementation of Physics-Informed Neural Networks ('PINN') for lifetime estimation under progressive Type-II censoring schemes. Combines parametric baseline hazards with physical differential degradation models. |
| License: | MIT + file LICENSE |
| Encoding: | UTF-8 |
| Imports: | deSolve, stats |
| Config/roxygen2/version: | 8.0.0 |
| NeedsCompilation: | no |
| Packaged: | 2026-08-05 07:02:56 UTC; Dr. O. J. Obulezi |
| Author: | Okechukwu J. Obulezi [aut, cre] |
| Maintainer: | Okechukwu J. Obulezi <oj.obulezi@unizik.edu.ng> |
| Repository: | CRAN |
| Date/Publication: | 2026-08-09 08:10:15 UTC |
Physics Residuals at Collocation Points
Description
Physics Residuals at Collocation Points
Usage
compute_ode_residuals(sol_colloc, z_colloc, phi, ode_func)
Arguments
sol_colloc |
Solved ODE states across collocation grid. |
z_colloc |
Collocation evaluation grid points. |
phi |
Physics differential parameters. |
ode_func |
Differential system function. |
Value
Vector of physical model residuals.
Default Physical ODE System (Degradation Process)
Description
Default Physical ODE System (Degradation Process)
Usage
default_ode_system(t, h, phi)
Arguments
t |
Time variable. |
h |
Current degradation state. |
phi |
Parameter vector governing the differential equation. |
Value
List containing derivative dh/dt.
Maximum Likelihood Estimation via PINN Optimization
Description
Maximum Likelihood Estimation via PINN Optimization
Usage
fit_pinn_progcens_mle(
times,
R,
z_colloc,
ode_func = default_ode_system,
max_epochs = 50
)
Arguments
times |
Observed progressive censored failure times. |
R |
Progressive removal counts. |
z_colloc |
Collocation points for differential equation loss. |
ode_func |
Differential system function. |
max_epochs |
Maximum optimization iterations. |
Value
List containing parameter estimates and standard errors.
Examples
times_obs <- c(0.85, 1.42, 2.10)
R_vec <- c(1, 0, 1)
colloc <- seq(0.1, 3.0, length.out = 5)
fit_pinn_progcens_mle(times_obs, R_vec, colloc, max_epochs = 5)
Interpolate Trajectory State
Description
Interpolate Trajectory State
Usage
interpolate_state(tau, sol_obs)
Arguments
tau |
Intermediary integration time. |
sol_obs |
Trajectory solution matrix. |
Value
Scalar estimated state value.
Physics-Regularized Hazard Rate Mapping
Description
Physics-Regularized Hazard Rate Mapping
Usage
pinn_hazard(t, alpha, beta, h_t, psi)
Arguments
t |
Evaluation time point. |
alpha |
Weibull scale parameter. |
beta |
Weibull shape parameter. |
h_t |
Degradation state at time t. |
psi |
List containing network weights W2 and bias b2. |
Value
Hazard rate value.
Examples
pinn_hazard(1.0, 1.0, 1.0, 0.5, list(W2 = matrix(1,1,1), b2 = 0))
Combined Structural Loss (Censored Likelihood + Physics Residual)
Description
Combined Structural Loss (Censored Likelihood + Physics Residual)
Usage
pinn_progcens_loss(params, times, R, z_colloc, ode_func, mu = 0.1)
Arguments
params |
List of current candidate parameters (alpha, beta, phi, psi). |
times |
Vector of observed failure times. |
R |
Vector of progressive censorship removals. |
z_colloc |
Vector of physics collocation evaluation points. |
ode_func |
Physics ODE differential system function. |
mu |
Physics loss regularization hyperparameter penalty weight. |
Value
Total scalar PINN structural loss value.
Softplus Activation Function
Description
Softplus Activation Function
Usage
softplus(x)
Arguments
x |
Numeric vector or matrix input. |
Value
Smooth approximation to ReLU.
Examples
softplus(c(-1, 0, 1))
Forward State Trajectory Integration
Description
Forward State Trajectory Integration
Usage
solve_ode_trajectory(times, phi, ode_func)
Arguments
times |
Vector of evaluation time points. |
phi |
Differential parameters. |
ode_func |
Right-hand-side differential equation function. |
Value
Matrix of interpolated trajectories at evaluated times.