notes

research and engineering notes on medical AI, scientific computing, safe RL, generative modeling, contrastive learning, and large-model systems


LLM RL: from Bellman Target, PPO Clip to Token/Sequence Ratio and Training-Inference Mismatch

A structured reinforcement learning tutorial from Bellman targets and policy gradients to PPO, GRPO, DAPO, CISPO, GSPO, DPO, and training-inference mismatch.

43 min read   ·   2026

Orthogonal Polynomials for Uncertainty Quantification: Recurrence Algorithms, PCE, and Biomedical Simulation

A research-level map of orthogonal polynomial recurrence algorithms, polynomial chaos expansion, and noninvasive uncertainty quantification for biomedical simulations.

9 min read   ·   2025

Contrastive Learning: Objectives, Dictionaries, Momentum Encoders, and Multimodal Alignment

从 anchor/positive/negative、dictionary 与 temperature 出发，梳理 Triplet、NCE/InfoNCE、NT-Xent、MoCo/SimCLR、BYOL/SimSiam/DINO、CLIP 以及 ArcFace/CosFace 的候选集合与表征几何。

36 min read   ·   2025

a distill-style blog post

an example of a distill-style blog post and main elements

25 min read   ·   2021

a post with code

an example of a blog post with some code

4 min read   ·   2015