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971.
We consider the Poisson equation −Δu=f with homogeneous Dirichlet boundary condition on a two-dimensional polygonal domain Ω with cracks. Multigrid methods for
the computation of singular solutions and stress intensity factors using piecewise linear functions are analyzed. The convergence
rate for the stress intensity factors is
whenfεL
2(Ω) and
whenfεH
1(Ω). The convergence rate in the energy norm is
in the first case and
in the second case. The costs of these multigrid methods are proportional to the number of elements in the triangulation.
The general case wherefεH
m
(Ω) is also discussed.
The work of the first author was partially supported by NSF under grant DMS-96-00133 相似文献
972.
Crawford G Daubenmier CM Fulton R Fujino D Gan KK Honscheid K Kagan H Kass R Lee J Sung M White C Wolf A Zoeller MM Butler F Fu X Nemati B Ross WR Skubic P Wood M Bishai M Fast J Gerndt E Hinson JW McIlwain RL Miao T Miller DH Modesitt M Payne D Shibata EI Shipsey IP Wang PN Battle M Ernst J Gibbons L Kwon Y Roberts S Thorndike EH Wang CH Dominick J Lambrecht M Sanghera S Shelkov V Skwarnicki T Stroynowski R Volobouev I Wei G Zadorozhny P Artuso M Gao M Goldberg M He D Horwitz N Moneti GC 《Physical review letters》1995,75(4):624-628
973.
Haseo Ki 《Transactions of the American Mathematical Society》1997,349(7):2845-2870
We show that the Denjoy rank and the Zalcwasser rank are incomparable. We construct for any countable ordinal differentiable functions and such that the Zalcwasser rank and the Kechris-Woodin rank of are but the Denjoy rank of is 2 and the Denjoy rank and the Kechris-Woodin rank of are but the Zalcwasser rank of is 1. We then derive a theorem that shows the surprising behavior of the Denjoy rank, the Kechris-Woodin rank and the Zalcwasser rank.
974.
975.
976.
977.
Poly-gamma-glutamic acid (gamma-PGA) is a very promising biodegradable polymer that is produced by Bacillus subtilis. Gamma-PGA is water-soluble, anionic, biodegradable, and edible. This paper reviews the production of a strain of gamma-PGA and recent developments with respect to applications in terms of Ca absorption, moisturizing properties, gamma-PGA conjugation, super absorbent polymer, and so on. Our recent research shows that gamma-PGA can be used as an immune-stimulating and anti-tumor agent, especially at high molecular weight. 相似文献
978.
As a novel sensing system, N-(1-pyrenylmethyl) amide-appended calix[4]crown-5 (2) and crown-6 (3) have been newly synthesized. Judging from the fluorescence changes upon the addition of cations, 3 having crown-6 ring showed the Pb2+ ion selectivity over other cations tested regarding fluorescence quenching. Upon the Pb2+ ion coordination to two amide oxygen atoms with aid of crown ring, a reverse-photo-induced electron transfer (PET) occurs in such a way that electrons transfer from the pyrene groups to the electron deficient amide oxygen atoms to give a quenched fluorescence. By the addition of either HClO4 or triethylamine in the solution of 3, the fluorescence intensity decreased because of the reverse-PET from pyrene groups to protonated amide oxygen atoms and because of normal PET from the nitrogen anion formed by triethylamine to pyrene groups, respectively. For 3, NOR logic gate in which the strong fluorescence signal appears at 395 nm (output: 1) is operated only when neither of triethylamine nor Pb(ClO4)2 (inputs A and B) is added (A=B: 0). XNOR gate is also operated only when both of two inputs are added (triethylamine and HClO4, A=B: 1) or when neither of two inputs is added (A=B: 0). Then, for 3, new INHIBIT gate system was also designed using such combinational inputs as HClO4, Pb(ClO4)2 and triethylamine. 相似文献
979.
Seong‐Chan Park Dr. Joon‐Ki Kim Chang‐Woo Lee Eui‐Seong Moon Heon Kang Prof. Dr. 《Chemphyschem》2007,8(17):2520-2525
Proton transfer from the hydronium ion to NH3, CH3NH2, and (CH3)2NH is examined at the surface of ice films at 60 K. The reactants and products are quantitatively monitored by the techniques of Cs+ reactive‐ion scattering and low‐energy sputtering. The proton‐transfer reactions at the ice surface proceed only to a limited extent. The proton‐transfer efficiency exhibits the order NH3>(CH3)NH2=(CH3)2NH, which opposes the basicity order of the amines in the gas phase or aqueous solution. Thermochemical analysis suggests that the energetics of the proton‐transfer reaction is greatly altered at the ice surface from that in liquid water due to limited hydration. Water molecules constrained at the ice surface amplify the methyl substitution effect on the hydration efficiency of the amines and reverse the order of their proton‐accepting abilities. 相似文献
980.
1,4-Diphenylbutadiyne(DPB) and several olefins such as 2,3-dimethyl-2-butene, 1,4-cyclohexadiene and dimethyl fumarate were irradiated with 300 nm UV light to obtain interesting cross-cycloaddition products. 相似文献