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1.
Some theoretical aspects of elastic wave modeling with a recently developed spectral element method 总被引:1,自引:0,他引:1
SERIANI Geza 《中国科学G辑(英文版)》2007,50(2):185-207
A spectral element method has been recently developed for solving elastodynamic problems. The numerical solutions are obtained by using the weak formulation of the elastodynamic equation for heterogeneous media, based on the Galerkin approach applied to a partition, in small subdomains, of the original physical domain. In this work, some mathematical aspects of the method and the associated algorithm implementation are systematically investigated. Two kinds of orthogonal basis functions, constructed with Legendre and Chebyshev polynomials, and their related Gauss-Lobatto collocation points are introduced. The related integration formulas are obtained. The standard error estimations and expansion convergence are discussed. An element-by-element pre-conditioned conjugate gradient linear solver in the space domain and a staggered predictor/multi-corrector algorithm in the time integration are used for strong heterogeneous elastic media. As a consequence, neither the global matrices nor the effective force vector is assembled. When analytical formulas are used for the element quadrature, there is even no need for forming element matrix in order to further save memory without losing much in computational efficiency. The element-by-element algorithm uses an optimal tensor product scheme which makes this method much more efficient than finite-element methods from the point of view of both memory storage and computational time requirements. This work is divided into two parts. The first part mainly focuses on theoretical studies with a simple numerical result for the Che-byshev spectral element, and the second part, mainly with the Legendre spectral element, will give the algorithm implementation, numerical accuracy and efficiency analyses, and then the detailed modeling example comparisons of the proposed spectral element method with a pseudo-spectral method, which will be seen in another work by Lin, Wang and Zhang. 相似文献
2.
Strong white light emission is observed from femtosecond laser propagation in air. The divergence angle of the white light emission is measured to be about 5mrad. Young's double-slits and a Michelson interferometer are used to investigate the coherence. The wavelength components of the white light emission are identified to have a good spatial coherence and a coherence time of about 0.5ps. 相似文献
3.
LI ChenYu LUO XiaoLiang ZHAO WeiJun HUANG Zhe LIU ZhengPing TONG Bin DONG YongQiang 《中国科学:化学(英文版)》2013,56(9):1173-1177
Luminescent materials exhibiting emission switching in the solid state have drawn much attention though there is still no clear design strategy for such materials. In this letter, we reported the crystallization induced emission enhancement (CIEE) of di(4-ethoxyphenyl)dibenzofulvene (1), and achieved switching its emission among four different colors through modulation of its molecular packing patterns. We have investigated its potential application as optical recording materials. The twisted conformations of CIEE compounds afford morphology dependent emission and facilitate tuning their emission through modulation of molecular packing patterns. Thus we provide a possible design strategy for solid stimulus responsive luminescent materials. 相似文献
4.
正We appreciate the comment from Horne,Miller and Wang on the paper‘A numerical investigation of the acoustic mode waves in a deviated borehole penetrating a transversely isotropic formation’by Liu et al.(2015)[1],for the opportunity to consider and clarify the group and phase velocity issue in sonic logging with a deviated borehole penetrating a VTI formation.We re-read the paper by Liu et al.[1]and did some numerical tests and analyses.After discussions we agree that at low 相似文献
5.
超声反应条件下,以氧化银、2,2’-二苯基二羧酸(H2bpda)及柔性配体1,3.-(4-吡啶)丙烷(bpp)为原料,在1:1的甲醇-水混合溶剂中合成了一个全新的银配合物IAg4(bpda)2-(bpp)4·14H2O·2CH3OH]n(1),并对该配合物进行了元素分析、红外光谱分析、热重分析以及晶体结构研究.X射线单晶结构分析表明,配合物1的空洞中包裹着一种由罕见的圣杯式十六核水簇、四个悬挂水分子及四个悬挂甲醇分子通过氢键作用所构筑的具有中心对称性的水-甲醇二元簇合物(H2O)20(CH3OH)4.其中的十六核水分子簇可看作由一组对称性相关的八核水簇相互耦合而成,而每个八核水则由两个折叠状的五核水通过共边形成.有趣地是,仔细分析发现目前的十六核水簇结构上非常类似由两个并环戊二烯通过[2+2]环加成而得到的一种复杂的有机烃,显示出水分子簇与有机分子结构上的相似性. 相似文献
6.
Influence of macroscopic graphite particulates on the damping properties of Zn-Al eutectoid alloy 总被引:1,自引:0,他引:1
JianNing Wei ShiHua Song KongGang Hu WeiJun Xie MingLiang Ma GenMei Li FuSheng Han 《中国科学G辑(英文版)》2009,52(1):70-75
The paper presents in detail the effects of macroscopic graphite (Gr) particulates on the damping behavior of Zn-Al eutectoid
alloy (Zn-Al). Macroscopic defects are graphite particulates with sizes of the order of a millimeter (0.5 mm and 1.0 mm).
Macroscopic graphite particulate-reinforced Zn-Al eutectoid alloys were prepared by the air pressure infiltration process.
The damping characterization was conducted on a multifunction internal friction apparatus (MFIFA). The internal friction (IF),
as well as the relative dynamic modulus, was measured at different frequencies over the temperature range of 20 to 400°C.
The damping capacity of the Zn-Al/Gr, with two different volume fractions of macroscopic graphite particulates, was compared
with that of bulk Zn-Al eutectoid alloy. The damping capacity of the materials is shown to increase with increasing volume
fraction of macroscopic graphite particulates. Two IF peaks were found in the IF-temperature curves. The first is a grain
boundary peak, which is associated with the diffusive flux on a boundary between like phases, Al/Al. Its activation energy
has been calculated to be 1.13±0.03 eV and the pre-exponential factor is 10−14 s in IF measurements. The second is a phase transition peak, which results from the transformation of Zn-Al eutectoid. In
light of internal friction measurements and differential scanning calorimetry (DSC) experiments, its activation energy has
been calculated to be 2.36±0.08 eV.
Supported by the Natural Science Foundation of Jiangxi Province of China (Grant No. 0550050) and the Jiangxi Provincial Department
of Education of China (Grant No. 13-3-B-04) 相似文献
7.
GengGeng Luo WeiJun He Li Liu ShengHui Wu DongXu Li ZiJing Xiao JingCao Dai 《中国科学:化学(英文版)》2012,55(12):2507-2514
A discrete centrosymmetric(H2O)20(CH3OH)4 binary cluster was confined in the cavity of a metal-ligand hybrid [Ag4(bpda)2(bpp)4·14H2O·2CH3OH] n(1)(where bpp = 1,3-bis(4-pyridyl)propane and H 2 bpda = 2,2’-biphenyldicarboxylic acid).The novel mixed water-methanol cluster consists of one grail-shaped hexadecameric cluster,four dangling water and four hanging methanol molecules.The(H 2 O) 16 cluster is composed of two pairs of edge-sharing(H2O) 5 rings attached to one(H2O) 4 core with twenty hydrogen bonds.Alternatively,the(H2O) 16 cluster is structurally similar to a complicated hydrocarbon generated by undergoing [2+2] cycloaddition of 1,2,3,4,5,6-hexahydropentalene,which reveals the resemblance between water clusters and organic compounds. 相似文献
8.
We determine the sizes of orbits from the action of subgroups of PSL(2,q) on projective line X = GF(q) ∪ {∞} with q a prime power and congruent to 1 modulo 4.As an example of its application,we construct some new families of simple 3-designs admitting PSL(2,q) as automorphism group. 相似文献
9.
Self-Starting Passively Mode-Locking All-Solid-State Laser with GaAs Absorber Grown at Low Temperature 总被引:4,自引:0,他引:4
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We realize a stable self-starting passively mode-locking all-solid-state laser by using novel GaAs mirrors as the absorber and output coupler. The GaAs mirror is grown by the technology of metal organic chemical vapour deposition at low temperature. With such an absorber as the output coupler in the laser resonator, laser pulses with duration of 42ps were generated at a repetition rate of 400MHz, corresponding to the average power of 590mW. 相似文献
10.