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991.
本文给出了具有两个抛线解的中心对称三次系统存在在极限环的条件,它可能也是充要条件。 相似文献
992.
J. Glimm H.C. Kranzer D. Tan F.M. Tangerman 《Communications in Mathematical Physics》1997,187(3):647-677
The Hamilton-Jacobi equation describes the dynamics of a hypersurface in . This equation is a nonlinear conservation law and thus has discontinuous solutions. The dependent variable is a surface
gradient and the discontinuity is a surface cusp. Here we investigate the intersection of cusp hypersurfaces. These intersections
define (n-1)-dimensional Riemann problems for the Hamilton-Jacobi equation. We propose the class of Hamilton-Jacobi equations as a
natural higher-dimensional generalization of scalar equations which allow a satisfactory theory of higher-dimensional Riemann
problems. The fist main result of this paper is a general framwork for the study of higher-dimensional Riemann problems for
Hamilton-Jacobi equations. The purpose of the framwork ist to unterstand the structure of Hamilton-Jacobi wave interactions
in an explicit and constructive manner. Specialized to two-dimensional Riemann problems (i.e., the intersection of cusp curves
on surfaces embedded in ), this framework provides explicit solutions to a number of cases of interest. We are specifically interested in models
of deposition and etching, important processes for the manufacture of semiconductor chips.
We also define elementary waves as Riemann solutions which possess a common group velocity. Our second main result, for elementary
waves, is a complete characterization in terms of algebraic constraints on the data. When satisfied, these constraints allow
a consistently defined closed form expression for the solution. We also give a computable characterization for the admissibility
of an elementary wave which is inductive in the codimension of the wave, and which generalizes the classical Oleinik condition
for scalar conservation laws in one dimension.
Received: 9 September 1996 / Accepted: 22 April 1997 相似文献
993.
994.
Duan-Ming Tan 《Tetrahedron letters》2005,46(3):503-505
Chiral arsinooxazoline Ru(II) complex has been found to be an efficient catalyst for asymmetric transfer hydrogenation of aromatic ketones in 2-propanol. Secondary alcohols with up to 94% enantiomeric excess were obtained at a substrate/catalyst mole ratio of 1000:1. Asymmetric kinetic resolution has also been obtained with 1-arylalkanols at room temperature with 99% ee. 相似文献
995.
This paper deals with the solvability of boundary value problems for singular integral equations of the form (i)-(ii).By an algebraic method we reduce the problem (i)-(ii) to a system of linear algebraic equations which gives all solutions in a closed form.AMS Subject Classification: 47G05, 45GO5, 45E05 相似文献
996.
室温下的永久性光谱烧孔 总被引:1,自引:1,他引:0
本文首次报导了Sm2+掺杂的碱土金属氟卤化物在室温下的光谱烧孔.室温下永久性光谱烧孔的实现,将对频域光存储的应用起到推动作用. 相似文献
997.
Yao Shi Xin Wang Wei Li Tian-en Tan Jian-jun Ruan 《Plasma Chemistry and Plasma Processing》2006,26(2):187-196
Effects of multiple corona reactor modes on pulse characteristics, energy transfer efficiency, and odor (H2S and NH3) removal were investigated experimentally by the wire-plate corona reactor(s). The removal efficiency of H2S was only 91% and the energy consumption was 16.1 Wh m−3 by the single mode with a gas-flow rate of 23 m3 h−1 and an initial concentration of 200 mg m−3. At the same experimental conditions, almost 100% removal efficiency was achieved and the energy consumption was only 12.8 and 14.9 Wh m−3 by the series and parallel modes. In the case of 50 mg m−3 NH3 removal at the same gas-flow rate, the removal efficiencies with the single mode, the series and parallel modes were 64, 92 and 70%, respectively. The energy requirement did not increase at the same residence time under the experimental conditions of the single mode with a gas-flow rate of 11.5 m3 h−1 and the series or parallel mode with a gas-flow rate of 23.0 m3 h−1. The experimental results indicate that the series and parallel modes are effective in saving energy consumption, improving removal ability and efficiency, especially for the series mode. 相似文献
998.
Yanning Yu Chongyi Wan Yan Lv Rongqing Tan Jinwen Zhou Shiming Liu Chong Zhao 《Optics & Laser Technology》2005,37(7):294-562
A high average power line-tunable TEA CO2 laser is described. Average output power up to 3 kW is achieved at repetition rate of 180 Hz. The maximum output power is almost equal among the four spectrum bands of CO2 laser (the P and R branches of 00°1–10°0 and 00°1–02°0 transition bands). Several special technologies including rotating spark gap switching, PCB (printed circuit board) preionization and zeroth-order grating coupling are employed. 相似文献
999.
Jian‐Wen Tan Ji‐Bin Xu Ze‐Jun Dong Du‐Qiang Luo Ji‐Kai Liu 《Helvetica chimica acta》2004,87(4):1025-1028
Nigricanin ( 1 ), the first ellagic acid related derivative from higher fungi, has been isolated from the fruiting bodies of the Basidiomycetes Russula nigricans. The structure of the novel compound was established by spectroscopic and chemical methods. 相似文献
1000.
Qiang Zheng Wanjie Wang Qiuming Yu Jei Yu Li He Hong Tan 《Journal of Polymer Science.Polymer Physics》2006,44(9):1309-1319
Studies on the nonlinear viscoelastic behavior of styrene‐[ethylene‐(ethylene‐propylene)]‐styrene block copolymer (SEEPS) were carried out. The nonlinear viscoelastic region was determined through dynamic strain sweep test, and the critical shear strain (γc) of transition from linear viscoelastic region to nonlinear viscoealstic region was obtained. The relaxation time and modulus corresponding to the characteristic relaxation modes were also acquired through simulating the linear relaxation modulus curves using Maxwell model, and the damping functions were evaluated. Meanwhile, it is found that the nonlinear relaxation modulus obtained at relatively low shear strains follows the strain–time separation principle, and the damping function of SEEPS can be fit to Laun double exponential model well. Moreover, the successive start‐up of shear behavior, the steady shear behavior, and the relaxation behavior after steady shear were investigated, respectively. The results showed that Wagner model, derived from the K‐BKZ (Kearsley‐Bernstein, Kearsley, Zapas) constitutive equation, could simulate the experiment data well, and in addition, experiment data under the lower shear rates are almost identical with the fitting data, but there exists some deviation for data under considerable high shear rates. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 1309–1319, 2006 相似文献