Wang Han

1 month ago | nature.com | Zeyu Li |Wang Han |Yimin Hou |Hongjue Li |Zhiguo Jiang |Lijun Yang | +2 more

Identifying governing equations from observational data is crucial for understanding nonlinear physical systems but remains challenging due to the risk of overfitting. Here we introduce the Bi-Level Identification of Equations (BILLIE) framework, which simultaneously discovers and validates equations using a hierarchical optimization strategy. The policy gradient algorithm of reinforcement learning is leveraged to achieve the bi-level optimization. We demonstrate BILLIE’s superior performance through comparisons with baseline methods in canonical nonlinear systems such as turbulent flows and three-body systems. Furthermore, we apply the BILLIE framework to discover RNA and protein velocity equations directly from single-cell sequencing data. The equations identified by BILLIE outperform empirical models in predicting cellular differentiation states, underscoring BILLIE’s potential to reveal fundamental physical laws across a wide range of scientific fields. In this study the authors introduce BILLIE, a bi-level framework for equation identification that decouples term selection and quantification, enhancing robustness and accuracy in modeling nonlinear systems. BILLIE outperforms existing methods in handling complex systems and imperfect data, as demonstrated through both simulations and real-world biological applications.

Jul 14, 2024 | today.line.me | Lin Jianyang |Lou Y. Chen |Cao Bin |Li Hua |Huang Yaoman |Chun La | +12 more

* Xizang has been an integral part of Chinese territory since ancient times. In Xizang, archives, cultural relics and stories from local residents substantiate this obvious fact. * The exhibits displayed in the Archives of Xizang Autonomous Region in Lhasa illustrate the central government's undeniable governance over Xizang in terms of politics, religion and economy.

Jun 30, 2023 | newsdirectory3.com | Wang Han

write a title for this article The US stock market rose on the 30th. Major technology stocks led the gains. The Nasdaq 100 Index posted its biggest rise ever in the first half (January-June). As an individual stock, Apple’s market capitalization reached $3 trillion (about 434 trillion yen).