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31.
In this paper we study the computational cost of solving theconvection-diffusion equation using various discretization strategiesand iteration solution algorithms. The choice of discretizationinfluences the properties of the discrete solution and alsothe choice of solution algorithm. The discretizations consideredhere are stabilized low-order finite element schemes using streamlinediffusion, crosswind diffusion and shock-capturing. The latter,shock-capturing discretizations lead to nonlinear algebraicsystems and require nonlinear algorithms. We compare variouspreconditioned Krylov subspace methods including Newton-Krylovmethods for nonlinear problems, as well as several preconditionersbased on relaxation and incomplete factorization. We find thatalthough enhanced stabilization based on shock-capturing requiresfewer degrees of freedom than linear stabilizations to achievecomparable accuracy, the nonlinear algebraic systems are morecostly to solve than those derived from a judicious combinationof streamline diffusion and crosswind diffusion. Solution algorithmsbased on GMRES with incomplete block-matrix factorization preconditioningare robust and efficient. 相似文献
32.
M.J. Kim S. Ajimura K. Aoki A. Banu H. Bhang T. Fukuda O. Hashimoto J.I. Hwang S. Kameoka B.H. Kang E.H. Kim J.H. Kim T. Maruta Y. Miura Y. Miyake T. Nagae M. Nakamura S.N. Nakamura H. Noumi S. Okada Y. Okayasu H. Outa H. Park P.K. Saha Y. Sato M. Sekimoto S. Shin T. Takahashi H. Tamura K. Tanida A. Toyoda K. Tsukada T. Watanabe H.J. Yim 《Physics letters. [Part B]》2006
33.
Tomofumi NagaeH. Hotchi H. Outa H. Noumi M. Sekimoto T. Fukuda H. C. Bhang Y. D. Kim J. H. Kim H. Park L. I. Tang R. Sawafta K. Tanida O. Hashimoto H. Tamura T. Saito T. Takahashi Y. Sato T. Endo S. Satoh J. Nishida T. Miyoshi T. Kishimoto A. Sakaguchi S. Ajimura Y. Shimizu T. Mori S. Minami M. Sumihama 《Nuclear Physics A》2000,670(1-4):269-272
We have measured an excitation energy spectrum of a Λ-hypernucleus Λ89Y via the (π+, K+) reaction by using the SKS spectrometer at KEK. The best quality data with the energy resolution of 1.63 MeV(FWHM) was obtained in the highest statistics so far. In the spectrum, we can find a splitting of the f-orbital of a Λ particle with the separation of 1.6±0.15 MeV(statistical error only), which may be attributed to the spin-orbit splitting. 相似文献
34.
Yamamoto S Zalipska J Aliu E Andringa S Aoki S Argyriades J Asakura K Ashie R Berghaus F Berns H Bhang H Blondel A Borghi S Bouchez J Burguet-Castell J Casper D Catala J Cavata C Cervera A Chen SM Cho KO Choi JH Dore U Espinal X Fechner M Fernandez E Fukuda Y Gomez-Cadenas J Gran R Hara T Hasegawa M Hasegawa T Hayashi K Hayato Y Helmer RL Hiraide K Hosaka J Ichikawa AK Iinuma M Ikeda A Inagaki T Ishida T Ishihara K Ishii T Ishitsuka M Itow Y Iwashita T Jang HI Jeon EJ Jeong IS Joo KK Jover G 《Physical review letters》2006,96(18):181801
We performed an improved search for nu(mu) --> nu(e) oscillation with the KEK to Kamioka (K2K) long-baseline neutrino oscillation experiment, using the full data sample of 9.2 x 10(19) protons on target. No evidence for a nu(e) appearance signal was found, and we set bounds on the nu(mu) --> nu(e) oscillation parameters. At Deltam(2)=2.8 x 10(-3) eV(2), the best-fit value of the K2Knu(mu) disappearance analysis, we set an upper limit of sin(2)2theta(mue) < 0.13 at a 90% confidence level. 相似文献
35.
Kang BH Bhang H Kim EH Kim JH Kim MJ Yim HJ Ajimura S Miyake Y Aoki K Nagae T Noumi H Outa H Saha PK Sato Y Sekimoto M Toyoda A Banu A Fukuda T Hashimoto O Kameoka S Miura Y Nakamura SN Okayasu Y Takahashi T Tamura H Tsukada K Watanabe T Hwang JI Maruta T Nakamura M Okada S Park H Tanida K 《Physical review letters》2006,96(6):062301
We performed a coincidence measurement of two nucleons emitted from the nonmesonic weak decay of lambda(5)He formed via the 6Li(pi+, K+) reaction. The energies of the two nucleons and the pair number distributions in the opening angle between them were measured. In both np and nn pairs, we observed a clean back-to-back correlation coming from the two-body weak reactions of lambda p --> np and lambda n --> nn, respectively. The ratio of the nucleon pair numbers was N(nn)/N(np) = 0.45 +/- 0.11(stat) +/- 0.03(syst) in the kinematic region of cos theta(NN) < -0.8. Since each decay mode was exclusively detected, the measured ratio should be close to the ratio of gamma(lambda p --> np)/gamma(lambda n --> nn). The ratio is consistent with recent theoretical calculations based on the heavy meson and/or direct-quark exchange picture. 相似文献
36.
Background
Animals must frequently act to influence the world even when the reinforcing outcomes of their actions are delayed. Learning with action-outcome delays is a complex problem, and little is known of the neural mechanisms that bridge such delays. When outcomes are delayed, they may be attributed to (or associated with) the action that caused them, or mistakenly attributed to other stimuli, such as the environmental context. Consequently, animals that are poor at forming context-outcome associations might learn action-outcome associations better with delayed reinforcement than normal animals. The hippocampus contributes to the representation of environmental context, being required for aspects of contextual conditioning. We therefore hypothesized that animals with hippocampal lesions would be better than normal animals at learning to act on the basis of delayed reinforcement. We tested the ability of hippocampal-lesioned rats to learn a free-operant instrumental response using delayed reinforcement, and what is potentially a related ability – the ability to exhibit self-controlled choice, or to sacrifice an immediate, small reward in order to obtain a delayed but larger reward. 相似文献37.
Fabrication of polystyrene hollow microspheres as laser fusion targets by optimized density-matched emulsion technique and characterization 总被引:3,自引:0,他引:3
Inertial confinement fusion, frequently referred to as ICF, inertial fusion, or laser fusion, is a means of producing energy
by imploding small hollow microspheres containing thermonuclear fusion fuel. Polymer microspheres, which are used as fuel
containers, can be produced by solution-based micro-encapsulation technique better known as density-matched emulsion technique. The specifications of these microspheres are very rigorous, and various aspects of the emulsion hydrodynamics associated
with their production are important in controlling the final product. This paper describes about the optimization of various
parameters associated with density-matched emulsion method in order to improve the surface smoothness, wall thickness uniformity
and sphericity of hollow polymer microspheres. These polymer microshells have been successfully fabricated in our lab, with
3–30 μm wall thickness and 50–1600 μm diameters. The sphericity and wall thickness uniformity are better than 99%. Elimination
of vacuoles and high yield rate has been achieved by adopting the step-wise heating of W1/O/W2 emulsion for solvent removal. 相似文献
38.
Ahn MH Aoki S Bhang H Boyd S Casper D Choi JH Fukuda S Fukuda Y Gajewski W Hara T Hasegawa M Hasegawa T Hayato Y Hill J Ichikawa AK Ikeda A Inagaki T Ishida T Ishii T Ishitsuka M Itow Y Iwashita T Jang HI Jang JS Jeon EJ Jung CK Kajita T Kameda J Kaneyuki K Kato I Kearns E Kibayashi A Kielczewska D Kobayashi K Kim BJ Kim CO Kim JY Kim SB Kobayashi T Kohama M Koshio Y Kropp WR Learned JG Lim SH Lim IT Maesaka H Martens K Maruyama T Matsuno S Mauger C McGrew C Mine S Miura M Miyano K Moriyama S 《Physical review letters》2003,90(4):041801
The K2K experiment observes indications of neutrino oscillation: a reduction of nu(mu) flux together with a distortion of the energy spectrum. Fifty-six beam neutrino events are observed in Super-Kamiokande (SK), 250 km from the neutrino production point, with an expectation of 80.1(+6.2)(-5.4). Twenty-nine one ring mu-like events are used to reconstruct the neutrino energy spectrum, which is better matched to the expected spectrum with neutrino oscillation than without. The probability that the observed flux at SK is explained by statistical fluctuation without neutrino oscillation is less than 1%. 相似文献
39.
40.
H. Outa S. Ajimura K. Aoki H. Bhang T. Hasegawa O. Hashimoto H. Hotchi Y. D. Kim T. Kishimoto K. Maeda H. Noumi Y. Ohta K. Omata H. Park Y. Sato M. Sekimoto T. Shibata T. Takahashi M. Youn 《Nuclear Physics A》2000,670(1-4):281-284
Results are reported on the precise measurement of the lifetime and the weak-decay branching ratios with charged particle(π− and proton) emission from Λ12C formed via 12C(π+,K+) reaction. The π− mesonic decay width is consistent with the calculations including the pion wave function distortion effect. We observed large contribution of the neutron-stimulated decay widths, Γ(Λ + n → n + n), in the non-mesonic weak decay, which cannot be explained by the current theoretical calculations. 相似文献