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INPAC-Seminar 92: Algebraically-Stabilized E |
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作者：Saturnman
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周三, 2012年 05月 02日 16:11 |
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INPAC-Seminar 92 Title: Algebraically-Stabilized Explicit Integration Of Extremely Stiff Reaction Networks Speaker: Prof. Mike Guidry (Department of Physics and Astronomy, University of Tennessee, Physics Division, Oak Ridge National Laboratory, and Computer Science and Mathematics Division, Oak Ridge National Laboratory) Time and place: 13:00, May 4 (Friday), 2012, Lecture Hall/INPAC (上海交通大学粒子物理宇宙学研究所，包玉刚图书馆东楼四楼(从北门进)) Abstract Differential equations containing multiple, widely-separated timescales are termed "stiff". Textbooks routinely state that implicit methods must be used to solve such equations because stability limits on the timestep size make explicit integration completely impractical. In direct contradiction to this prevailing view in the literature, this talk will show that even extremely stiff sets of ordinary differential equations may be solved efficiently by explicit methods if limiting algebraic solutions are used to stabilize the numerical integration. Using stringent tests with astrophysical thermonuclear networks, evidence is provided that these methods can deal with the stiffest networks, even in the approach to equilibrium, with accuracy and integration timestepping comparable to that of standard implicit methods. Explicit algorithms can execute a timestep faster and scale more favorably with network size than implicit algorithms. Thus, these results suggest that algebraically-stabilized explicit methods might enable integration of larger reaction networks coupled to fluid dynamics than has been feasible previously for many applications in astrophysics and a variety of other disciplines. |
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最后更新 ( 周三, 2012年 05月 02日 16:13 )
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INPAC-Seminar 91: Nuclear Incompressibility, |
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作者：Saturnman
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周二, 2012年 04月 24日 14:23 |
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INPAC-Seminar 91 Title: Nuclear Incompressibility, the Asymmetry Term, and the MEM Effect Speaker: Prof. Umesh Garg (University of Notre Dame/Peking University) Time and place: 13:00, April 27 (Friday), 2012, Lecture Hall/INPAC (上海交通大学粒子物理宇宙学研究所，包玉刚图书馆东楼四楼(从北门进)) Abstract The Nuclear Incompressibility parameter is one of three important components characterizing the nuclear equation of state. It has crucial bearing on diverse nuclear and astrophysical phenomena, including radii of neutron stars, strength of supernova collapse, emission of neutrinos in supernova explosions, and collective flow in medium- and high-energy nuclear collisions. In this talk I will review current status of the research on direct experimental determination of nuclear incompressibility via the compressional-mode giant resonances. In particular, recent measurements on a series of Sn and Cd isotopes have provided an "experimental" value for the asymmetry term of nuclear incompressibility. We also find that the GMR centroid energies of both Sn and Cd isotopes are significantly lower than the theoretical predictions, pointing to the role of superfluidity and the MEM (Mutual Enhancement of Magicity) Effect. |
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最后更新 ( 周二, 2012年 04月 24日 14:25 )
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INPAC-Seminar 89: Hunting for the Higgs Boson and more at the LHC (Recent results from ATLAS) |
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作者：Saturnman
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周一, 2012年 04月 09日 06:59 |
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INPAC-Seminar 89 Title: Hunting for the Higgs Boson and more at the LHC (Recent results from ATLAS) Speaker: Prof. Peter Jenni (European Organization for Nuclear Research (CERN), Geneva, Switzerland) Time and place: 11:00, April 11 (Wednesday), 2012, Lecture Hall/INPAC (上海交通大学粒子物理宇宙学研究所，包玉刚图书馆东楼四楼(从北门进)) Abstract Since two years experiments at the Large Hadron Collider (LHC) have started exploring the physics at the high energy frontier. A rich harvest of initial physics results has been obtained by the ATLAS and CMS Collaborations that allow one already to test, at highest energies ever reached in a laboratory, the Standard Model (SM) of elementary particles, and to make searches Beyond the SM (BSM). Significant results have already been obtained in searches for the Higgs Boson, which would establish the postulated electro-weak symmetry breaking mechanism in the SM, as well as for BSM physics like Supersymmetry (SUSY), Extra Dimensions, production of new heavy particles and others. The status of these searches, and the future prospects at the LHC, will be covered in this talk. |
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最后更新 ( 周一, 2012年 04月 09日 07:01 )
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INPAC-Seminar 90: The giant monopole resonan |
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作者：Saturnman
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周二, 2012年 04月 17日 14:57 |
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INPAC-Seminar 90 Title: The giant monopole resonance, nuclear matter incompressibility and symmetry energy Speaker: Dr. Yiu-Wing Lui (Cyclotron Institute, Texas A&M University, College Station, TX, USA) Time and place: 13:00, April 20 (Friday), 2012, Lecture Hall/INPAC (上海交通大学粒子物理宇宙学研究所，包玉刚图书馆东楼四楼(从北门进)) Abstract The isoscalar giant monopole resonance (ISGMR) is of interest because it’s energy EGMR can be related to the compressibility of nuclear matter KNM. Using beam of 240 MeV α particles from the K500 superconducting cyclotron at Texas A&M university, the experimental measurements were made with inelastic scattering of 240 MeV α particles at small angles including 0º. Properties of ISGMR have been established in 28 nuclei between 12C and 208Pb. Experimental setup, data analysis and extraction of the compressibility of nuclear matter will be discussed. Also comparison to theoretical calculations as well as current status of the nuclear matter compressibility will be presented. Finally symmetry energy obtained from the ISGMR is compared to values from other methods. |
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最后更新 ( 周二, 2012年 04月 17日 14:59 )
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INPAC-Seminar 88: The importance of a joint energy strategy - China and the U.S. |
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作者：Saturnman
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周二, 2012年 04月 03日 15:33 |
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INPAC-Seminar 88 Title: The importance of a joint energy strategy - China and the U.S. Speaker: Prof. Lee Riedinger (University of Tennessee Knoxville, USA) Time and place: 14:00, April 6 (Friday), 2012, Lecture Hall/INPAC (上海交通大学粒子物理宇宙学研究所，包玉刚图书馆东楼四楼(从北门进)) Abstract The United States is struggling to find its appropriate energy strategy for the next 50 years. Many see the need for increased supply of electricity from nuclear and from renewable sources, decreased burning of coal, and growing dependence on natural gas from abundant shale deposits. Implementation of wind turbines and solar photovoltaic arrays is increasing, especially for the former. But, the associated challenges for wind and solar are profound, e.g., siting to maximize the efficiency of each and storage to smooth or shift in time the supply of electricity to the grid. These plans and challenges are similar to those in China, which calls for increased collaboration between the two largest users of energy in the world. One area of cooperation could be in education and research. We have developed a new interdisciplinary PhD program in Energy Science and Engineering between the University of Tennessee and Oak Ridge National Laboratory. Building collaborations between this new doctoral program and similar directions at a few universities in China could be one way to foster greater cooperation between these two large countries in issues related to energy supply and use. |
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最后更新 ( 周二, 2012年 04月 03日 15:35 )
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