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191.
A fast mesh deformation method using explicit interpolation 总被引:1,自引:0,他引:1
A novel mesh deformation algorithm for unstructured polyhedral meshes is developed utilizing a tree-code optimization of a simple direct interpolation method. The algorithm is shown to provide mesh quality that is competitive with radial basis function based methods, with markedly better performance in preserving boundary layer orthogonality in viscous meshes. The parallelization of the algorithm is described, and the algorithm cost is demonstrated to be O(n log n). The parallel implementation was used to deform meshes of 100 million nodes on nearly 200 processors demonstrating that the method scales to large mesh sizes. Results are provided for a simulation of a high Reynolds number fluid–structure interaction case using this technique. 相似文献
192.
The ground state ab initio CCSD(T) potential curves using various basis sets (aug-cc-pVXZ-PP (X = D, T, Q, 5)) is obtained for the dimers of helium with IIb group metals. The effect of the position of the (mid) bond-functions on the interaction energy is discussed. A Symmetry Adapted Perturbation Theory decomposition of the interaction energy is provided and the trends in the dimer stabilizing and destabilizing contributions are depicted. The spline fitted potential curves are applied together with rigorous statistical formulae in order to obtain the transport coefficients (viscosity coefficients, diffusion coefficients) and the second virial coefficient both for pure constituents and mixtures. The obtained theoretical results are compared with available experimental data. Molecular dynamics is used to obtain reliable values of the diffusion coefficients for all the systems under study. 相似文献
193.
Molecular Origin of Strain-Induced Chain Alignment in PDPP-Based Semiconducting Polymeric Thin Films
Song Zhang Amirhadi Alesadi Gage T. Mason Kai-Lin Chen Guillaume Freychet Luke Galuska Yu-Hsuan Cheng P. Blake J. St. Onge Michael U. Ocheje Guorong Ma Zhiyuan Qian Sujata Dhakal Zachary Ahmad Cheng Wang Yu-Cheng Chiu Simon Rondeau-Gagné Wenjie Xia Xiaodan Gu 《Advanced functional materials》2021,31(21):2100161
Donor–acceptor (D–A) type semiconducting polymers have shown great potential for the application of deformable and stretchable electronics in recent decades. However, due to their heterogeneous structure with rigid backbones and long solubilizing side chains, the fundamental understanding of their molecular picture upon mechanical deformation still lacks investigation. Here, the molecular orientation of diketopyrrolopyrrole (DPP)-based D–A polymer thin films is probed under tensile deformation via both experimental measurements and molecular modeling. The detailed morphological analysis demonstrates highly aligned polymer crystallites upon deformation, while the degree of backbone alignment is limited within the crystalline domain. Besides, the aromatic ring on polymer backbones rotates parallel to the strain direction despite the relatively low overall chain anisotropy. The effect of side-chain length on the DPP chain alignment is observed to be less noticeable. These observations are distinct from traditional linear-chain semicrystalline polymers like polyethylene due to distinct characteristics of backbone/side-chain combination and the crystallographic characteristics in DPP polymers. Furthermore, a stable and isotropic charge carrier mobility is obtained from fabricated organic field-effect transistors. This study deconvolutes the alignment of different components within the thin-film microstructure and highlights that crystallite rotation and chain slippage are the primary deformation mechanisms for semiconducting polymers. 相似文献
194.
Let be a graph with a list assignment . Suppose a preferred color is given for some of the vertices; how many of these preferences can be respected when -coloring ? We explore several natural questions arising in this context, and propose directions for further research. 相似文献
195.
G.M. Luke K. Kojima M. Larkin J. Merrin B. Nachumi Y.J. Uemura G.M. Kalvius A. Brückl K. Neumaier K. Andres G. Nakamoto M. Sirasi H. Tanaka T. Takabatake H. Fujii M. Ishikawa 《Hyperfine Interactions》1997,104(1-4):199-203
We present zero and longitudinal field μ SR measurements of single crystal and polycrystalline specimens of the heavy fermion
compound CePt2Sn2. Above 1 K the behaviour of the two samples is indistinguishable; the muon 1/T_1 increases with decreasing temperature until
25 K when it plateaus. The 1/T_1 relaxation rate differs strongly for the two cases below \sim\,0.8\ K. At 0.1 K a rate of
about 20 μ s-1 is seen in the polycrystal while in the single crystal it is only about 5 μ s-1. Even more revealing is the fact that longitudinal field decoupling spectra at very low temperatures demonstrate an essentially
static spin system to be present in the polycrystalline material while the single crystal shows definite dynamic spin properties.
We conclude that, in the presence of the distortion, long range magnetic order occurs below 0.9 K while in tetragonal symmetry
long range order is suppressed (probably due to frustration) and spin fluctuations remain for T\rightarrow0.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
196.
B. Nachumi A. Keren K. Kojima M. Larkin G.M. Luke J. Merrin O. Tchernyshöv W.D. Wu Y.J. Uemura Y. Fukuzumi K. Mizuhashi K. Takenaka S. Uchida 《Hyperfine Interactions》1997,105(1-4):125-130
We report the muon spin rotation experiments on Zn substituted La1-x Srx CuO4, for four zinc concentrations y=0.0,0.0025,0.005,0.01, at strontium concentrations x=0.15,0.20. We find that T_ c in the
optimally doped (x=0.15) and overdoped (x=0.20) 2:1:4 decreases linearly with increasing zinc concentration. Plotted against
the planar zinc concentration, the Tc’s of both series seem to fall on the same line. The superconducting carrier density/effective mass ratio, n_ s/m*, at first decreases linearly, rising above this line for higher zinc concentrations. This behavior may result from the localization
of carriers in an area \xiab around each zinc atom.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
197.
M. Mekata T. Asano H. Nakamura M. Shiga K. Kojima G.M. Luke A. Keren W.D. Wu Y.J. Uemura S. Dunsinger M. Gingras 《Hyperfine Interactions》1997,104(1-4):337-342
The relaxation rate of muon polarization of Y0.97Sc0.03Mn2 with a magnetic lattice composed of corner‐shared tetrahedrons shows a broad peak around 2.5 K indicating a random spin freezing
at low temperatures. The substitution by nonmagnetic Al atoms for 10% Mn atoms raises the spin freezing temperature to 45
K. The present work shows clearly that due to the strong geometrical frustration, the ground state of the system is singlet
tetrahedrons mixed with frozen paramagnetic tetrahedrons.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
198.
199.
G.M. Luke K. Kojima M. Larkin J. Merrin B. Nachumi Y.J. Uemura Y. Nakamura S. Uchida M. Crawford 《Hyperfine Interactions》1997,105(1-4):113-117
We present μSR experiments on La2-x Bax CuO4 and La1.6-x Nd0.4 Srx CuO4 for x=0.125. Both of these materials order magnetically with TN\approx30\ K, while a superconducting sample of La1.4 Nd0.4 Sr0.2 CuO4 showed no evidence for static copper moments. Our results support the conclusion that the so‐called “1/8” anomaly in La2-x Bax CuO4 is a result of static (pinned) charge segregation.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
200.
S.R. Dunsiger R.F. Kiefl K.H. Chow B.D. Gaulin M.J.P. Gingras J.E. Greedan A. Keren K. Kojima G.M. Luke W.A. MacFarlane N.P. Raju J.E. Sonier Y.J. Uemura W.D. Wu 《Hyperfine Interactions》1997,104(1-4):275-280
In a system where magnetic ions occupy the vertices of edge or corner sharing triangular units, the natural antiferromagnetic
coupling between ions is geometrically frustrated. A wide variety of interesting magnetic behaviour has been observed in pyrochlores,
where magnetic ions form a network of corner sharing tetrahedra. The low temperature spin dynamics of a number of pyrochlores
A2B2O7 have been investigated using the technique of μ SR. For example, Y2Mo2O7 shows a transition to a disordered magnetic state similar to a spin glass at TF=22 K. However, unlike conventional metallic spin glasses, a non‐zero muon spin depolarization rate is observed to persist
well below 0.1\ TF. These results suggest that there is a finite density of states for magnetic excitations in this system near zero energy.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献