A high order boundary scheme to simulate complex moving rigid body under impingement of shock wave

In the paper, we study a high order numerical boundary scheme for solving the complex moving boundary problem on a fixed Cartesian mesh, and numerically investigate the moving rigid body with the complex boundary under the impingement of an inviscid shock wave. Based on the high order inverse Lax-Wendroff(ILW) procedure developed in the previous work(TAN, S. and SHU, C. W. A high order moving boundary treatment for compressible inviscid flows. Journal of Computational Physics, 230(15),6023–6036(2011)), in which the authors only considered the translation of the rigid body,we consider both translation and rotation of the body in this paper. In particular, we reformulate the material derivative on the moving boundary with no-penetration condition, and the newly obtained formula plays a key role in the proposed algorithm. Several numerical examples, including cylinder, elliptic cylinder, and NACA0012 airfoil, are given to indicate the effectiveness and robustness of the present method.

A two-phase fluid model for epidemic flow

We propose a new mathematical and computational modeling framework that in-corporates fluid dynamics to study the spatial spread of infectious diseases.We model the susceptible and infected populations as two inviscid fluids which interact with each other.Their motion at the macroscopic level characterizes the progression and spread of the epidemic.To implement the two-phase flow model,we employ high-order numerical methods from computational fluid dynamics.We apply this model to simulate the COVID-19 outbreaks in the city of Wuhan in China and the state of Tennessee in the US.Our modeling and simulation framework allows us to conduct a detailed investigation into the complex spatiotemporal dynamics related to the transmission and spread of COVID-19.

Enhanced N_(2)-to-NH_(3)conversion efficiency on Cu3P nanoribbon electrocatalyst

Ambient electroreduction of nitrogen(N_(2))is considered as a green and feasible approach for ammonia(NH_(3))synthesis,which urgently demands for efficient electrocatalyst.Morphology has close relationship with catalytic activity of heterogeneous catalysts.Nanoribbon is attractive nanostructure,which possesses the flexibility of one-dimensional nanomaterials,the large surface area of two-dimensional nanomaterials,and lateral size confinement effects.In this work,Cu_(3)P nanoribbon is proposed as a highly efficient electrocatalyst for N_(2)-to-NH_(3)conversion under benign conditions.When measured in N_(2)-saturated 0.1 M HCl,such Cu_(3)P nanoribbon achieves high performance with an excellent Faradaic efficiency as high as 37.8%and a large yield of 18.9μg·h^(−1)·mgcat.−1 at−0.2 V.It also demonstrates outstanding stability in long-term electrolysis test at least for 45 h.

Facing small and biased data dilemma in drug discovery with enhanced federated learning approaches

Artificial intelligence(AI)models usually require large amounts of high-quality training data,which is in striking contrast to the situation of small and biased data faced by current drug discovery pipelines.The concept of federated learning has been proposed to utilize distributed data from different sources without leaking sensitive information of the data.This emerging decentralized machine learning paradigm is expected to dramatically improve the success rate of AI-powered drug discovery.Here,we simulated the federated learning process with different property and activity datasets from different sources,among which overlapping molecules with high or low biases exist in the recorded values.Beyond the benefit of gaining more data,we also demonstrated that federated training has a regularization effect superior to centralized training on the pooled datasets with high biases.Moreover,different network architectures for clients and aggregation algorithms for coordinators have been compared on the performance of federated learning,where personalized federated learning shows promising results.Our work demonstrates the applicability of federated learning in predicting drug-related properties and highlights its promising role in addressing the small and biased data dilemma in drug discovery.

Strong tunability of cooperative energy transfer in Mn2＋-doped （Yb3＋, Er3＋）/NaYF4 nanocrystals by coupling with silver nanorod array

Fluorescent rare-earth ions are useful for efficient energy transfer via multi- channels with different properties. Tuning these transfer processes in functional rare-earth materials has attracted considerable attention to satisfy the various demands of diverse practical applications. In this study, strong tunabilities of cooperative energy transfer and nonlinear upconversion emissions are realized using （Yb3＋, Er3＋）/NaYF4 nanocrystals with and without doped Mn2~ ions by adopting a plasmonic nanocavity composed of a silver nanorod array. The plasmon nanocavity can not only increase the energy transfer between Mn2＋ and （Yb3＋, Er3＋） but also significantly enhance the radiative emission. This reveals a prominent nonlinear gain in the nanocavity nanosystems. These observations suggest the prospective applications in the design and preparation of rare-earth nanocrystals with excellent tunabilities of multiple functionalities.

Numerical simulation of a complex moving rigid body under the impingement of a shock wave in 3D

In this paper,we take a numerical simulation of a complex moving rigid body under the impingement of a shock wave in three-dimensional space.Both compressible inviscid fluid and viscous fluid are considered with suitable boundary conditions.We develop a high order numerical boundary treatment for the complex moving geometries based on finite difference methods on fixed Cartesian meshes.The method is an extension of the inverse Lax-Wendroff(ILW)procedure in our works(Cheng et al.,Appl Math Mech(Engl Ed)42:841-854,2021;Liu et al.)for 2D problems.Different from the 2D case,the local coordinate rotation in 3D required in the ILW procedure is not unique.We give a theoretical analysis to show that the boundary treatment is independent of the choice of the rotation,ensuring the method is feasible and valid.Both translation and rotation of the body are taken into account in this paper.In particular,we reformulate the material derivative for inviscid fluid on the moving boundary with no-penetration condition,which plays a key role in the proposed algorithm.Numerical simulations on the cylinder and sphere are given,demonstrating the good performance of our numerical boundary treatments.