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81.
A second order accurate method in the infinity norm is proposed for general three dimensional anisotropic elliptic interface problems in which the solution and its derivatives, the coefficients, and source terms all can have finite jumps across one or several arbitrary smooth interfaces. The method is based on the 2D finite element-finite difference (FE-FD) method but with substantial differences in method derivation, implementation, and convergence analysis. One of challenges is to derive 3D interface relations since there is no invariance anymore under coordinate system transforms for the partial differential equations and the jump conditions. A finite element discretization whose coefficient matrix is a symmetric semi-positive definite is used away from the interface; and the maximum preserving finite difference discretization whose coefficient matrix part is an M-matrix is constructed at irregular elements where the interface cuts through. We aim to get a sharp interface method that can have second order accuracy in the point-wise norm. We show the convergence analysis by splitting errors into several parts. Nontrivial numerical examples are presented to confirm the convergence analysis. 相似文献
82.
Coupled identical oscillators with resistive couplings are investigated. Various antiphase states are observed. The bifurcation threshojds for the antiphase states of coupled van der Pol oscillators and the unstable modes of these systems at the bifurcation points are explicitly compu ted. The dependence of antiphase states on system size and coupling length is investigated in detail. General coupled limit cycle models are also investigated. The realizations of antiphase states can be explained, based on the global potential analysis. 相似文献
83.
气候变化对浙江沿海风暴潮的影响 总被引:1,自引:0,他引:1
基于浙江沿海多个气象观测站和潮位观测站近50年的气温、潮位及风暴潮的资料,研究了气候变化背景下浙江沿海台风暴潮变化特征.分析表明,随着沿海地区年平均气温的上升,浙江沿海相对海平面、登陆台风、超警戒风暴潮、较大风暴增水、年极值高潮位等都呈现出上升或增多趋势;在此背景下,浙江沿海风暴潮灾害风险也随之增大,特别是2000年以来,登陆浙江沿海的台风个数和最大增水超过300cm的风暴潮次数都显著增多.对气候变化背景下浙江沿海风暴潮灾害的影响分析,将为今后风暴潮预警及防灾、减灾的应对提供重要的启示和参考. 相似文献
84.
N.?A.?SkoptsovEmail author I.?A.?Denisov A.?M.?Malyarevich K.?V.?Yumashev O.?S.?Dymshits A.?A.?Zhilin I.?P.?Alekseeva 《Journal of Applied Spectroscopy》2011,78(5):650-658
Luminescence regularities have been studied in new erbium/ytterbium materials based on glasses and glass ceramics of a magnesium-aluminosilicate
system containing nanoscale erbium/ytterbium zirconate titanate crystals with the pyrochlore structure. Lifetimes of Yb3+ and Er3+ ions in the 2 F5/2 state and in the 4I11/2 and 4I13/2 states, respectively, and the efficiency of Yb3+ → Er3+ energy transfer have been evaluated. The identified spectral-luminescent characteristics of the studied glasses and glass
ceramics co-doped with erbium and ytterbium ions show that these materials are promising media for producing laser generation
in the spectral range around 1.5 μm. 相似文献
85.
The rates of DPPH (diphenylpicrylhydrazyl) trapping and the sonolytical products obtained during the sonolysis of thioethers at normal and low temperature are reported. CS2, lower sulfides, thiophene, and sulfurized species are the common products during the ultrasonic irradiations. Hydrocarbons are also obtained during the sonolysis of diallyl sulfide, diethyl disulfide, and dipropyl disulfide. Furthermore, aldehydes are obtained as oxidized species; SO2 is found at 208 K. The principal sonochemical process appears to be the cleavage of C-S or S-S bond with secondary combinations and rearrangements. DPPH has been used to probe the sonolytical potential of thioethers. The results show a good correlation between the rates of DPPH trapping and the vapor pressures of thioethers. In conclusion, a lower vapor pressure results in a higher sonolytical rate. The sonochemical behaviors of thioethers have strong qualitative similarities to the pyrolysis. 相似文献
86.
87.
Aristov VY Molodtsova OV Maslyuk VV Vyalikh DV Zhilin VM Ossipyan YA Bredow T Mertig I Knupfer M 《The Journal of chemical physics》2008,128(3):034703
The electronic structure of the organic semiconductor copper-phthalocyanine (CuPc) has been determined by a combination of conventional and resonant photoemission, near-edge x-ray absorption, as well as by the first-principles calculations. The experimentally obtained electronic valence band structure of CuPc is in very good agreement with the calculated density of states results, allowing the derivation of detailed site specific information. 相似文献
88.
Numerical Algorithms - Recently, an augmented IIM (Li et al. SIAM J. Numer. Anal. 55, 570–597 2017) has been developed and analyzed for some interface problems. The augmented IIM can provide... 相似文献
89.
The paper deals with the existence of positive continuous solutions to systems of nonlinear Hammerstein integral equations. The main tool used in the proofs is fixed point index theory in a cone. The results obtained here are essentially different from existing ones in the literature. 相似文献
90.
ZnS:Eu2+的长余辉发光 总被引:11,自引:2,他引:9
Eu2+的5d能级在许多晶体中都低于其4f能级的最低激发态(6P7/2),因此发光呈带状光谱,且发射波长随基质变化很大。由于5L→4f是容许跃迁,所以发光的衰减很快,通常在μs数量级,出人意料的是ZnS:Eu的发光尽管也是Eu2+的5d→4f跃迁,但衰减却极慢,达几十分钟的数量级。弛豫曲线的分析表明,这种长的弛豫是电子陷阱造成的。 相似文献