-
报告题目：非平衡结晶过程的动力学路径及设计原理Dynamical Pathways and Design Principles of Nonequilibrium Crystallization报告人：谭鹏时间：2026年10月20日9:55-10:40地点：1100号校区达理楼一楼报告厅摘要：Crystallization is conventionally described as a thermally activated process governed by nucleation barriers and diffusive growth. However, far from equilibrium, crystallization may proceed through multiple competing metastable states, making the actual transformation strongly pathway dependent. In this talk, I will discuss our recent studies of nonequilibrium crystallization from the perspective of dynamical pathways. Single-particle observations first revealed nonclassical nucleation involving precursor structures and cross-symmetry structural transformations. We then showed that confinement and curvature can reorganize defects and select crystallization morphologies. At ultralow temperatures, crystals can grow from glassy states through cooperative, nearly diffusionless ordering, demonstrating that crystallization does not necessarily require long-range particle diffusion. More recently, we found that impurities can induce a bifurcation between continuous growth and melting-recrystallization pathways. Finally, dual-symmetry-guided assembly demonstrates that sparse structural information can reshape pathway accessibility and efficiently guide the formation of complex lattices. Together, these results suggest a general picture in which nonequilibrium crystallization is governed not only by thermodynamic driving forces, but also by the accessibility and connectivity of dynamical pathways in a complex metastable landscape. This perspective provides a route from understanding naturally selected crystallization pathways toward their active design and control.报告人简介：谭鹏，复旦大学物理学系教授。2010年获复旦大学凝聚态物理博士学位，随后在香港中文大学从事博士后研究，2014年回国在复旦大学开展独立科研工作。长期从事非平衡结晶、玻璃态动力学及复杂体系结构与动力学研究，在非经典形核、限域结晶、玻璃态结晶、多层级弛豫和结晶路径调控等方面开展了系列工作。相关成果发表于 Nature、Nature Physics、Nature Materials 等期刊。现主持国家自然科学基金青年科学基金项目（A类）等科研项目。
2026-10-15
-
报告题目：Topology Optimization with Phase-Field Methods报告人：朱升峰时间：2026年10月20日9:10-9:55地点：1100号校区达理楼一楼报告厅摘要：This talk presents recent advances in our group for topology optimization based on phase-field methods. First, a phase-field model for coupled thermal-fluid design is introduced, including well-posedness, existence of optimal designs, adjoint-based sensitivity analysis, finite element discretization, and efficient gradient-flow algorithms. Second, alternating phase-field Fourier neural networks are developed as a mesh-free framework that separately represents state, adjoint, and topology variables for compliance minimization, eigenvalue maximization, and design of fluid flows. Numerical results will be reported.报告人简介：朱升峰，华东师范大学数学科学学院教授、博导，浙江大学学士、博士，瑞士洛桑联邦理工学院博士后。研究偏微分方程数值方法、拓扑优化、形状优化、模型降阶等。在Numerische Mathematik、SINUM、SISC、SICON、IP、JCP、CMAME等权威期刊发表论文90余篇。主持基金委、上海市科委及重庆市科研项目等，参与国家重点研发计划项目与上海市科委应用数学重点项目。入选上海市东方英才计划拔尖项目，获上海市自然科学奖二等奖（1/2）。现任上海市系统工程学会理事，担任期刊 Control and Cybernetics、Approximation Theory and Special Functions 编委及 Communications in Nonlinear Science and Numerical Simulation 客座编辑。
2026-10-15
-
-
-
报告题目：Semidefinite Programming Bounds for Designs on Spheres and Hamming Spaces报告人：Wei-Hsuan Yu时间：2026年9月29日14:00-15:00地点：第四教学楼215摘要：We use semidefinite programming(SDP) methods for spherical codes and energy minimization to improve lower bounds for designs on spheres and Hamming spaces in low-dimensional cases. In particular, we use the SDP to improve the bounds for Hamming designs (or orthogonal arrays, equivalently) and the harmonic index 4-designs on spheres.报告人简介：Wei-Hsuan Yu is an associate professor in the Department of Mathematics at National Central University. He received his Ph.D. in Mathematics from the University of Maryland, College Park, under the supervision of Professor Alexander Barg. He was a fixed-term assistant professor at Michigan State University and a postdoctoral researcher at ICERM, Brown University.His research interests include algebraic combinatorics, discrete geometry, and coding theory, with a particular focus on two-distance sets, equiangular lines, and combinatorial designs. He has published many papers in highly prestigious journals such as Advances in Mathematics, Journal of Combinatorial Theory Series A, Physical Review Letters. Professor Yu is supported from Ministry of Science and Technology’s Outstanding Young Scholars Research Program, the NCTS Young Theorist Award.
2026-09-28
-
报告题目：Unit gain graphs with two eigenvalues and lines in complex space with few angles报告人：Edwin van Dam时间：2026年9月29日（星期二）下午13:00地点：第四教学楼 215教室摘要：Since the introduction of the Hermitian adjacency matrix for digraphs, interest in so-called complex unit gain graphs has surged. In this talk, we consider such gain graphs with two distinct eigenvalues. Analogously to (undirected) graphs whose traditional adjacency matrix has few distinct eigenvalues, a great deal of structural symmetry is required. Besides combinatorial considerations, also the representation by lines in complex space is essential in the study of considered gain graphs. Examples are drawn from various relevant concepts from quantum information theory related to lines in complex space with few angles, such as SIC-POVMs and MUBs. Other examples relate to the hexacode, Coxeter-Todd lattice, and the Van Lint-Schrijver association scheme. Many other examples can be obtained as induced subgraphs by employing a technique parallel to the dismantling of certain association schemes. Specific examples thus arise from (partial) spreads in some small generalized quadrangles. Finally, we give a full classification of two-eigenvalue gain graphs with degree at most 4, or with a multiplicity at most 3.报告人简介：Edwin R. van Dam is currently a Full Professor in the Department of Econometrics and Operations Research at Tilburg University, the Netherlands. He obtained his Ph.D. from Tilburg University.His main research interests include algebraic graph theory, spectral graph theory, distance-regular graphs, association schemes, and the use of eigenvalue methods in combinatorics. Professor van Dam has published over 100 papers in highly prestigious journals such as Inventiones Mathematicae, Journal of Combinatorial Theory Series A, Journal of Combinatorial Theory Series B. He is an Editor-in-Chief of the Electronic Journal of Combinatorics.。
2026-09-24
