2017年度中山大学国际青年学者珠海论坛中法核工程与技术学院分论坛学术报告会 International Young Scholars Zhuhai Forum of Institut Franco-chinois de L’énergie Nucléaire
报告时间：13:00 - 13:30
报告人：刘莉 (Li Liu)
报告题目: Visualizing Nano-Scale Sub-surface Complex Phenomena: Experiments to Theories
While current generation of simulation tools and computing power allow fundamental physics level understanding of complex materials and systems, it is extremely essential to perform experiments tailored to test the physics modules of those tools. Unbiased experimental and theoretical analysis is becoming increasingly the bottleneck of a successful understanding. We believe, on the other hand, that the functions of systems depend on their fundamental nano-scale physics.
We introduce some of the unsolved mysteries of water, liquids, and alloys at surfaces and interfaces, and demonstrate recent progress in solving them. It is important to understand that the methodology we are developing is beyond normal observable surfaces by electron microscopes. In other words, we are focusing on liquids, sub-surface and interfaces of solids, and/or liquid-solid interactions.
We look into methodology development based on neutron and X-ray scattering techniques to “visualize” the complex phenomena. This visualization must integrate scattering experimental analysis, simulation, and theory to provide real space images of such phenomena. And their potential use in exploring energy, medical materials/imaging, and engineering processes is highly promising.
Dr. Liu is a tenured Associate Professor of Nuclear Engineering and Engineering Physics in the Department of Mechanical, Aerospace, and Nuclear Engineering at Rensselaer Polytechnic Institute (RPI). Dr. Liu earned her PhD from the Massachusetts of Technology and her B.S. from Peking University. She is the recipient of various honors and awards such as the Arab-American Frontiers Fellowship (National Academies of Sciences, Engineering, and Medicine of USA, 2017), the Class of 1951 Outstanding Teaching Award (RPI, 2013), the School of Engineering Research Excellence Award (RPI, 2012), and the Cozzarelli Prize in Engineering and Applied Sciences from Proceedings of the National Academy of Sciences (2006). As a Physicist and Nuclear Engineer by training, Liu’s research is focused on solving high impact problems associated with energy and the environment through fundamental investigations into the structure-function relationships of materials. For this purpose she is developing a variety of experimental and computational tools based on neutron, X-ray, and light scattering as well as molecular dynamics (MD) and phase field simulations.
报告题目: Fracture behavior of AA2198 Al-Cu-Li alloys for aeronautic applications
The influence of microstructure on plastic anisotropy and fracture toughness of two grade 2198 Al-Cu-Li alloys was investigated. Two heat treatment conditions were studied for each grade. Multiscale characterization techniques including optical micrography, transmission electron microscopy and X-ray computed tomography have been used to identify materials microstructure and damage micro-mechanisms. Plastic anisotropy and thickness effect on plasticity have been investigated via tensile tests on smooth flat and notched flat specimens showing an anisotropic plastic behavior along different loading directions. Ductile tearing behavior was examined using small sized Kahn specimens and large panels M(T) tests. Fractography via scanning electron microscopy and synchrotron radiation computed tomography have clarified the intergranular and transgranular mechanisms of fracture with respect to grain structure and heat treatment. The finite element simulation of ductile tearing is based on the local approach to fracture using cohesive zone model.
Dr Jianqiang CHEN received his BS in 2005 from Nanjing University of Aeronautics and Astronautics, Nanjing, China and diplôme d’ingénieur in 2007 from Ecole des Mines d’Albi, Albi, France and PhD in 2011 from Ecole des Mines de Paris-ParisTech, Paris, France. He is currently Researcher in Mechanics of Materials, Department of Mechanical Engineering, Ecole de technologie Superieure, Montreal, Canada. Dr Chen’s research covers a wide range of advanced materials and manufacturing processes optimization, including: aeronautic metallic materials and its joint technique, fatigue and damage of materials. Dr Chen’s work has been well-received by academia and industry. He is the member of Ordre des Ingenieur, ASME, ASM etc.
报告时间：14:00 - 14:30
报告人：卢凯 (Kai Lu)
报告题目: Plasticity Correction on Stress Intensity Factors of Underclad Cracks in Reactor Pressure Vessels
Structural integrity assessment of reactor pressure vessels (RPVs) is an important issue to ensure the safe operation of aging nuclear power plants. For RPVs in pressurized water reactors, the severe pressurized thermal shock (PTS) event can occur. In this situation, the stress intensity factor (SIF) is evaluated for a postulated underclad crack near the inner surface of an RPV. Since the cladding made of stainless steel has a lower yield stress compared with the base metal, the plasticity effect of cladding should be considered in SIF calculations of underclad cracks. This report presents results obtained from finite element analyses for Japanese RPVs containing underclad cracks under PTS events. In addition, a plasticity correction method was proposed on SIF calculations of underclad cracks in Japanese RPVs. Moreover, several verification studies were performed to verify the applicability of the proposed method on SIF evaluation of underclad cracks in RPVs.
Kai Lu, who got his PhD degree of engineering in the field of Nuclear Power & Energy Safety Engineering from University of Fukui in March, 2015. From April, 2015, he has been working in Japan Atomic Energy Agency as a post-doctoral fellow. His research interests are and mainly focused on structural integrity assessments of cracked components like the reactor pressure vessels in nuclear power plants, pipelines, etc. He has published 6 papers in SCI journals and 14 conference papers (7 for international conferences and 7 for domestic conferences in Japan). He is the reviewer for SCI journals such as Theoretical & Applied Fracture Mechanics, International Journal of Mechanical Sciences, and Applied Mathematical Modelling. His research achievements were awarded in the ASME PVP international conference. He was invited to attend the expert meeting for several times, and was also invited to visit the Research Center for Power Engineering Problems of the Russian Academy of Sciences.
报告时间：14:30 - 15:00
报告人：刘瑞瑞 (Ruirui Liu)
报告题目: Integrated Spatial and Temporal Stochastic Model in Radiation Biology: Design, Implementation, and Application
Mathematical modeling plays a pivotal role in understanding the mechanism of radiation effect on the cell, and also in quantifying the radiation risk to the cell. Radiation damage to a biological system is a complicated multiscale problem in space. In this work, an integrated spatial and temporal stochastic model was developed to study the radiation effect on biological cells. The model could be used to create the computerized cell, to simulate the radiation transportation process in the cell, to quantify the DNA damage production in the cell, to quantify the cell state evolution dynamics, and to quantify the biological effect of the cell.
The detail process for simulating the radiation-induced effect in this study were: (1) building a cell and tissue model, (2) calculating the spatial dose distribution using Monte Carlo methods on the cell model, (3) calculating the bio-parameters based on the calculation by the Monte Carlo method, (4) calculating the cellular and tissue ra- diation response using bio-modeling method based on the calculated bio-parameters; and, (5) calculating the radiation risk in a comprehensive way including direct damage and indirect damage to cells. All these processes (which consist of radiation physics simulation and biological simulation) are key steps towards building a comprehen- sive mechanism for understanding the radiation-induced effect. The proposed ISST model includes five modules which serve the tools to simulate the major inter-steps of formation of radiation-induced effects. The five modules are Cell Maker, Transport Solver, Physical-Bio Translator, Cell Simulator, and Radiation Risk Analyzer.
The model was implemented based on multi-platform simulation. A simula- tion package was developed based on the proposed models and two particular cases: radiation-induced bystander effect and radiation therapy treatment plan simulation, were studied using the developed package. The simulation results show that the devel- oped model could be used to facilitate the investigation of radiation biology. We hope that this work will shed light on building a comprehensive mathematical modeling tool for computational radiation biology.
Dr. Liu is a PhD student at Oregon State University, Corvallis, Oregon, USA. He has seven Journal papers in the field of Radiation Protection. Eight oral presentations in international conference. He has two issued patents in China and his research interests are Computational Medical Physics, Radiation Transport Simulation, Radiation Detection, Radiation Dosimetry, Computational Radiation Biology and Radiation Protection Design etc.
茶歇&合影:15:00 - 15:20
报告时间：15:20 - 15:50
报告人：陆智伦 (Zhilun Lu)
报告题目: Thermoelectric Oxides and Neutron Scattering
Most state-of-the-art thermoelectrics with high Figures of Merit values are composed of toxic, naturally rare and heavy metal elements. As a result, further work is required to develop new, low-cost, stable materials based on oxides. Excellent properties for p-type oxides have already been reported. However, n-type oxides with equivalent ZT values have yet to be discovered to date. SrTiO3-based systems have attracted considerable attention due to their high thermoelectric properties by so-called donor-doping with higher valence ions on the A- or B-site, especially lanthanum-doped SrTiO3 (LST). In this talk, I will introduce a successful strategy by creating A- site and O deficiency in the perovskite structure to improve the thermoelectric performance by reducing thermal conductivity and increasing the electrical conductivity, simultaneously. Then, the highest ZT value reported for n-type SrTiO3 based ceramics has been achieved.
Neutron scattering is ‘an excellent probe’ to study the structure and dynamic properties of materials. Inelastic neutron scattering probes the atomic and molecular motion, magnetic, and lattice excitations of materials by measuring changes in the neutron momentum and energy simultaneously. The cold three-axis spectrometer, FLEXX, is a work- horse instrument for inelastic neutron scattering matching the sample environment capabilities at HZB. It offers a big variety of operating modes: standard triple axis spectrometer (TAS), high resolution spin- echo, and a multiplexing backend called MultiFLEXX. The MultiFLEXX option allows the simultaneous measurement of multiple wave vectors and energy.
Doctor Lu currently works as a postdoc researcher in Helmholtz-Zentrum Berlin für Materialien und Energie, one research center of the largest scientific organisation in Germany-Helmholtz Association of German Research Centres. I obtained my PhD degree from University of Sheffield, UK, on January 2016 with the High Quality PhD Thesis Prize. My main research covers neutron scattering, neutron resonance spin echo spectroscopy, thermoelectric oxides and geometrically frustrated magnets. I have improved thermoelectric properties of La-doped SrTiO3 successfully and achieved the best thermoelectric properties ever reported for n-type SrTiO3 based ceramics. This result has been published by Chemistry of Materials as a highly cited paper.
报告时间：15:50 - 16:20
报告人：陈佳跃 (Jiayue Chen)
报告题目: SCWR thermal-hydraulic studies: pipe and bundle heat transfer, flow instability, system code developing
The supercritical water cooled reactor (SCWR) is an innovative nuclear reactor concept with supercritical water as working coolant. Due to the strong variation of physical properties in the vicinity of pseudo-critical region, the flow and heat transfer behavior of supercritical fluids are different from those of subcritical fluids. Current understanding of thermal-hydraulics at supercritical pressures still remain some problems. Firstly, this report presents the experimental and numerical investigations of heat transfer characteristics in a pipe and a 19 rod-bundle. Some normal and deteriorated heat transfer results are discussed. The second section is focus on the supercritical flow instability issues. The developed frequency domain and time domain analysis method are presented. Some numerical analyses of supercritical flow instability in parallel channel flow are discussed. Last subject is on the SCWR system code developing. A numerically convenient solution of one-dimensional two-phase two-fluid model will be introduced. Some validations are discussed and the solution is extended to supercritical pressure conditions.
Jiayue Chen is currently Ph.D. candidate of Nuclear Science and Engineering department at Shanghai Jiao Tong University. His research major is experiment and simulation of nuclear reactor thermal-hydraulics. He has research experiences of inverse heat conduction problem, reactor accident simulation with RELAP5 code, heat transfer experiment and simulation in rod-bundle, two-fluid numerical method and system code developing.