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Academy of Mathematics and Systems Science, CAS Colloquia & Seminars：The study of derived representation type via topological and homological methods
拓扑 同调 派生表示类型
2023/11/13
In these two talks, some results on derived representation type via topological and homological methods will be introduced: (1) Two geometric models for graded skew-gentle algebras will be introduced ...
Academy of Mathematics and Systems Science, CAS Colloquia & Seminars：Kahler geometry methods in Gaussian Gabor frame theory
高斯 Gabor框架理论 Kahler几何
2023/11/6
We investigate the frame set of regular multivariate Gaussian Gabor frames using methods from Kahler geometry such as Hormander's $\dbar$-L2 estimate with singular weight, Demailly's Calabi--Yau metho...
Academy of Mathematics and Systems Science, CAS Colloquia & Seminars：Machine learning methods for forward and inverse PDEs
正反向 偏微分方程 机器学习
2023/4/27
本报告介绍我们近期的两项工作。(1) 求解PDE的PINN方法在处理时间发展方程时往往遇到难以收敛的困难。我们发展了时间方向的预训练PINN方法及自适应步长方法，解决了收敛性困难，使PDE求解精度能够得到系统性提高。我们在一系列时间发展方程上获得了比文献报道更精确的训练结果。(2) 辐射调源问题是一个典型的反问题，要求调整辐射输运方程的边条件(源)，使解满足特定设计目标。我们针对辐射输运方程的时序...
Academy of Mathematics and Systems Science, CAS Colloquia & Seminars：Space-time finite and boundary element methods for the wave equation
波动方程 时空有限元 边界元方法
2023/4/21
In this talk we will review some recent results on space-time finite and boundary element methods for the wave equation. As a first model problem we consider the inhomogeneous wave equation with zero ...
Academy of Mathematics and Systems Science, CAS Colloquia & Seminars：Improved error estimates of the splitting methods for the long-time dynamics for the weakly nonlinear Schrodinger equations
弱非线性薛定谔方程 长时间动力学 分裂方法 误差估计
2023/4/21
We establish improved uniform error bounds for the time-splitting methods for the long-time dynamics of the nonlinear Schr\"odinger equation (NLSE) with weak nonlinearity. By a new technique of regula...
Academy of Mathematics and Systems Science, CAS Colloquia & Seminars：Arbitrarily high-order cut-off methods to preserve maximum bound principle for Allen-Cahn equations
Allen-Cahn equations 最大界限原理 任意高阶 截止方法
2023/4/14
A new class of high-order maximum principle preserving numerical methods is proposed for solving the semilinear Allen-Cahn equation. We start with the method consists of a $k$th-order multistep expone...
Academy of Mathematics and Systems Science, CAS Colloquia & Seminars：Stochastic approximation methods for nonconvex constrained optimization
非凸 约束优化 随机逼近方法
2023/4/14
Nonconvex constrained optimization (NCO) has been one of the important research fields in optimization community. It has widely appeared in many application fields. However, challenges for solving NCO...
南京农业大学农学院《Science of The Total Environment》发表智慧农业团队“Improving the spatial and temporal estimation of ecosystem respiration using multi-source data and machine learning methods in a rainfed winter wheat cropland”（图）
智慧农业 碳循环 生态系统
2023/10/28
2023年2月25日，农学院智慧农业团队在《Science of The Total Environment》期刊发表了题为“Improving the spatial and temporal estimation of ecosystem respiration using multi-source data and machine learning methods in a rainfed ...
Academy of Mathematics and Systems Science, CAS Colloquia & Seminars：Convergence analysis of one-point large deviations rate functions of numerical methods for stochastic wave equations with small noise
小噪声 随机波动方程 数值方法 单点大偏差率 函数收敛分析
2023/4/21
In this talk, we present the pointwise convergence of one-point large deviations rate functions (LDRFs) of the spatial finite difference method and further the fully discrete method based on the tempo...
Academy of Mathematics and Systems Science, CAS Colloquia & Seminars：On the preservation of second integrals by RK methods
RK方法 保存 第二积分
2023/4/25
One can elucidate integrability properties of ODEs by knowing the existence of second integrals. However, little is known about how they are preserved, if at all, under numerical methods. In this talk...
Academy of Mathematics and Systems Science, CAS Colloquia & Seminars：Deep learning of multi-scale PDEs based on data generated from particle methods
粒子方法 数据 多尺度 偏微分方程 深度学习
2023/4/26
Solving multi-scale PDEs is difficult in high-dimensional and/or convection-dominant cases. The interacting particle methods (IPM) are shown to outperform solving PDEs directly. Examples include compu...
北京大学化学与分子工程学院彭海琳课题组与合作者Nature Methods ：超平整石墨烯/均匀薄冰支撑膜用于高分辨冷冻电镜成像（图）
彭海琳 Nature Methods 超平整石墨烯 冷冻电镜成像
2023/6/21
近日，北京大学化学与分子工程学院彭海琳课题组、清华大学生命科学学院王宏伟课题组和北京大学工学院韦小丁课题组合作在《自然-方法学》 (Nature Methods)发表了题为“Uniform thin ice on ultraflat graphene for high-resolution cryo-EM”的研究论文，报道了新型超平整石墨烯电镜载网，破解了高分辨冷冻电镜表征中均匀薄冰的制备难题。
Academy of Mathematics and Systems Science, CAS Colloquia & Seminars：Multiscale finite element methods: ideas and challenges
多尺度 有限元方法 思路 挑战
2023/5/6
Multiscale phenomena significantly impact on the computation and modeling for scientific and engineering problems. Multiscale finite element methods are used to build reduced order computational model...
Academy of Mathematics and Systems Science, CAS Colloquia & Seminars：First-order methods for convex optimization and monotone inclusions under local Lipschitz conditions
局部利普希茨条件 凸优化 单调夹杂物 一阶方法
2023/5/6
In this talk, we first consider convex optimization whose smooth components have a locally Lipschitz continuous gradient and propose a first-order method for finding an epsilon-KKT solution. We then c...
Academy of Mathematics and Systems Science, CAS Colloquia & Seminars：Domain Decomposition and Optimized Schwarz Methods for the Dual-porosity-conduit System
双重孔隙 导管系统 区域分解 优化Schwarz方法
2023/5/10
In this work, we propose and analyze domain decomposition methods to decouple the large system arisen from the discretization of dual-porosity-Stokes model. Robin boundary conditions are used to decou...