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Convergence of the Vlasov-poisson-Fokker-planck system to the incompressible Euler equations

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science china Mathematics 2006年第2期49卷 255-266页

作者： XIAO Ling, LI Fucai & WANG Shu Academy of Mathematics and Systems science, Chinese Academy of sciences, Beijing 100080, china Department of Mathematics, nanjing university, nanjing 210093, china College of Applied sciences, Beijing university of technology, Beijing 100022, china 1. Academy of Mathematics and Systems science Chinese Academy of Sciences Beijing 100080 China 2. Department of Mathematics Nanjing University Nanjing 210093 China 3. College of Applied sciences Beijing University of Technology Beijing 100022 China

We establish the convergence of the Vlasov-poisson-Fokker-planck system to the incompressible Euler equations in this paper. The convergence is rigorously proved on the time interval where the smooth solution to the incompressible Euler equations exists. The proof relies on the compactness argument and the so-called relative-entropy method.

关键词： Vlasov-poisson-Fokker-planck system incompressible Euler equations relative-entropy method.

AN INVESTIGATION ON ASM TUrBULENCE MODEL IN prEDICTIING NONISOTrOpIC TUrBULENT FLOWS

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Journal of Hydrodynamics 1991年第2期3卷 81-87页

作者： Yang Yong-quan Wu Chi-gong, Chengdu university of science and technology, Chengdu Sichuar 610065, p.r.china Chengdu Univ of science and Technology Chengdu China

Non-isotropy is evident for flows with large streamline curvature. Algebraic stress model can fairly simulate non-isotropy of turbulence. Some flow situations were investigated with a well developed ASM model. The calcu- lated results show that the distributions of reynolds stresses in different directions are obviously different. The non-isotropy of the flow is evident. The effect of streamline curvature on the flow feature of submerged water jet restricted by solid boundaries were studied, and its application in the design of energy dissipators of free trajectory jet type was disscused.

关键词： ASM AN INVESTIGATION ON ASM TUrBULENCE MODEL IN prEDICTIING NONISOTrOpIC TUrBULENT FLOWS

Composition Operators on the Bloch Space of Several Complex Variables

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Acta Mathematica Sinica,English Series 2000年第1期16卷 85-98页

作者： Jihuai Shi Luo Luo Department of Mathematics,university of science and technology of china,Heifei 230036,p.r.china Fax:(0551)3631760 Department of Mathematics University of Science and Technology of China Heifei 230036 P.R. China

In this paper,we study the boundedness and compactness of composition operator C on the Bloch space β（Ω）,Ω being a bounded homogeneous *** Ω=Bn,we give the necessary and sufficient conditions for a composition o... 详细信息

关键词： Bloch space Composition operator Bergman metric

THEOrETICAL ANALYSES AND NUMErICAL EXpErIMENTS FOr TWO-DIMENSIONAL WIND rETrIEVALS FrOM SINGLE-DOppLEr DATA

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Journal of Hydrodynamics 2010年第2期22卷 185-195页

作者： HUANG Si-xun CAO Xiao-qun DU Hua-dong ZHONG Ji-qin institute of Meteorology PLA University of Science and Technology Nanjing 211101 China National university of Defense Technolog Changsha 410073 China institute of Urban Meteorology China Meteorological Administration Beijing 100089 China

Based on variational adjoint methods,theoretical analyses and numerical experiments are performed for retrievals of two-dimensional winds and related parameters from single-Doppler radar data in polar *** the method,the reflectivity conservation equation is used as the governing equation and the mass continuity equation as a weak *** the same time,the stable functional of regularization and background field are also introduced in the cost *** on the ideal experiments with artificial data,real two-dimensional wind fields are retrieved with low-altitude data from the nanjing Doppler radar Station,and the results are encouraging and promising.

关键词： single-Doppler retrievals adjoint methods regularization methods two-dimensional wind

Dynamic Mechanical Behaviour of Ultra-high performance Fiber reinforced Concretes

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Journal of Wuhan university of technology(Materials science) 2008年第6期23卷 938-945页

作者：赖建中 Department of Materials science & Engineering Nanjing University of Science & Technology

Ultra-high performance fiber reinforced concretes （UHpFrC） were prepared by replacing 60% of cement with ultra-fine industrial waste powder. The dynamic mechanical behaviour of UHpFrC with different fiber volume fraction was researched on repeated compressive impact in four kinds of impact modes through split Hopkinson pressure bar （SHpB）. The experimental results show that the peak stress and elastic modulus decrease and the strain rate and peak strain increase gradually with the increasing of impact times. The initial material damage increases and the peak stress of the specimen decreases from the second impact with the increasing of the initial incident wave. Standard strength on repeated impact is defined to compare the ability of resistance against repeated impact among different materials. The rate of reduction of standard strength is decreased by fiber reinforcement under repeated impact. The material damage is reduced and the ability of repeated impact resistance of UHpFrC is improved with the increasing of fiber volume fraction.

关键词： ultra-high performance fiber reinforced concretes split Hopkinson pressurebar dynamic repeated impact

Variational construction of unbounded orbits in Lagrangian systems

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science china Mathematics 2010年第3期53卷 617-624页

作者： CHENG Chong-Qing 1, & LI Xia 2 1 Department of Mathematics, nanjing university, nanjing 210093, china 2 Department of Mathematics, Suzhou university of science and technology, Suzhou 215001, china 1. Department of Mathematics Nanjing University Nanjing 210093 China2. Department of Mathematics Suzhou University of Science and Technology Suzhou 215001 China

We show the existence of unbounded orbits in perturbations of generic geodesic flow in T2 by a generic periodic potential. Different from previous work such as in Mather (1997), the initial values of the orbits obtain... 详细信息

关键词： positive definite Lagrangian variational method unbounded orbit

Simulating the Folding pathway of rNA Secondary Structure Using the Modified Ant Colony Algorithm

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Journal of Bionic Engineering 2010年第4期7卷 382-389页

作者： Jun Yu~(1,2),Changhai Zhang~(1,2),Yuanning Liu~(1,2),Xin Li~(1,2) 1.College of Computer science and technology,Jilin university,Changchun 130012,p.r.china 2.Key Laboratory of Symbolic Computation and Knowledge Engineering (Ministry of Education,china) Jilin university,Changchun 130012,p.r.china [a] College of Computer science technology Jilin University Changchun 130012 P. R. China [b] Key Laboratory of Symbolic Computation Knowledge Engineering (Ministry of Education China) Jilin University Changchun 130012 P. R. China

A new method for simulating the folding pathway of rNA secondary structure using the modified ant colony algorithmis *** a given rNA sequence,the set of all possible stems is obtained and the energy of each stem iscalculated and stored at the initial ***,a more realistic formula is used to compute the energy ofmulti-branch loop in the following *** a folding pathway is simulated,including such processes as constructionof the heuristic information,the rule of initializing the pheromone,the mechanism of choosing the initial andnext stem and the strategy of updating the pheromone between two different *** by testing rNA sequences withknown secondary structures from the public databases,we analyze the experimental data to select appropriate values *** measure indexes show that our procedure is more consistent with phylogenetically proven structures thansoftware rNAstructure sometimes and more effective than the standard Genetic Algorithm.

关键词： rNA secondary structure folding pathway ant colony algorithm

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science china Chemistry 2004年第6期47卷 466-479页

作者： SONG Huajie1,2, XIAO Heming1 & DONG Haishan2 1. Department of Chemistry, nanjing university of science and technology, nanjing 210094, china 2. institute of Chemical Materials, china Academy of Engineering physics, Mianyang 621900, china 1. Department of Chemistry Nanjing University of Science and Technology 210094 Nanjing China 2. institute of Chemical Materials China Academy of Engineering Physics 621900 Mianyang China

The symmetry-adapted perturbation theory (SApT) that has the ability in decompo- sition of the total interaction energy into physically meaningful components is used to provide a more fundamental understanding of intermolecular forces. This work was motivated by the diffi- culty of standard SApT in computing the intermolecular interactions for large energetic dimer systems. SApT based on Kohn-Sham orbitals (SApT(DFT)) proves computationally efficient for these large systems, but has been shown to perform poorly for interaction energy components. The deficiencies of SApT(DFT) result from wrong asymptotical behaviors of commonly used exchange-correlation potentials. To remove the deficiencies, two asymptotic corrections by means of van Leeuwen and Baerends (LB) model potential and Fermi-Amaldi (FA) type potential were applied into three small test systems comprising He2, HF2 and (N2)2 and a set of larger ni- tramide dimers at several separations. The results showed that when utilizing newly developed frequency-dependent density susceptibilities (FDDS) technique for computing dispersion energy, the FA asymptotic correction is very effective to circumvent these deficiencies in SApT(DFT) and yields a good accuracy over the LB correction. The FA corrected SApT(DFT) approach is capa- ble of correctly predicting all the quantitative trends in binding energies for all test cases and substantially reduces computational cost as compared with the standard SApT calculations. The successful application of the approach to nitramide dimer demonstrates that it potentially pro- vides a good means to calculate accurately intermolecular forces in larger system such as en- ergetic systems.

关键词： intermolecular interaction, density functional theory (DFT), symmetry adapted perturbation theory (SApT), asymptotic correction, frequency-dependent density susceptibilities (FDDS).

prediction method for October 2003 solar storm

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science china(Technological sciences) 2006年第5期49卷 629-640页

作者： XIE Yanqiong1, 2, 3, WEI Fengsi1, FENG Xueshang1 & ZHONG Dingkun1, 2 1. State Key Laboratory of Space Weather, Center for Space science and Applied research, Chinese Academy of sciences, Beijing 100080, china 2. Graduate School, Chinese Academy of sciences, Beijing 100039, china 3. institute of Meteorology, pla university of science and technology, nanjing 211101, china State Key Laboratory of Space Weather Center for Space Science Applied research Chinese Academy of Sciences Beijing 100080 China Graduate School Chinese Academy of Sciences Beijing 100039 China institute of Meteorology PLA University of Science technology Nanjing 211101 China

Aiming at two intense shock events on October 28 and 29, 2003, this paper presents a two-step method, which combines synoptic analysis of space weather ——“observing” and quantitative prediction ——“palpating”, and then uses it to test predictions. In the first step of “observing”, on the basis of observations of the solar source surface magnetic field, interplanetary scintillation (IpS) and ACE spacecraft, we find that the propagation of the shocks is asymmetric relative to the normal direction of their solar sources, and the Earth is located near the direction of the fastest speed and the greatest energy of the shocks. As the two fast ejection shock events, the fast explosion of coronal mass of the extremely high temperature, the strong magnetic field, and the high speed background solar wind are also helpful to their rapid propagation. In the second step of “palpating”, we adopt a new membership function of the fast shock events for the ISF method. The predicted results show that for the onset time of the geomagnetic disturbance, the relative errors between the observational and the predicted results are 1.8% and 6.7%; and for the magnetic disturbance magnitude, the relative errors are 4.1% and 3.1%, re- spectively. Furthermore, the comparison among the predicted results of our two-step method with those of five other prevailing methods shows that the two-step method is advantageous. The results tell us that understanding the physical features of shock propagation thoroughly is of great importance in improving the prediction precision.

关键词： solar storm, interplanetary shock, interplanetary scintillation, two-step method, ISF method.