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51.
工件带到达时间的两阶段柔性流水作业的近似算法 总被引:1,自引:0,他引:1
研究了工件带到时间的两阶段柔性流水作业的排序问题,基于求解流水作业和平行机问题的算法思想,提出两个相应的近似算法H(R)和H(MR(?)),证明了这两个算法的最坏情况性能比分别为3-1/m和2/5-1/m,讨论了界的紧性,并利用数值模拟以分析算法与最优值的近似性能比. 相似文献
52.
Almost thirty years ago, Penny G. Estabrooks asked “Where and what are the scalar mesons?” (P. Estabrooks, Phys. Rev. D 19, 2678 (1979)). The first part of her question can now be confidently responded (E. van Beveren et al., Z. Phys. C 30, 615 (1986)). However, with respect to the “What” many puzzles remain unanswered. Scalar and axial-vector mesons form part
of a large family of mesons. Consequently, though it is useful to pay them some extra attention, there is no point in discussing
them as isolated phenomena. The particularity of structures in the scattering of --basically-- pions and kaons with zero angular
momentum is the absence of the centrifugal barrier, which allows us to “see” strong interactions at short distances. Experimentally
observed differences and similarities between scalar and axial-vector mesons on the one hand, and other mesons on the other
hand, are very instructive for further studies. Nowadays, there exists an abundance of theoretical approaches towards the
mesonic spectrum, ranging from confinement models of all kinds, i.e., glueballs, and quark-antiquark, multiquark and hybrid configurations, to models in which only mesonic degrees of freedom
are taken into account. Nature seems to come out somewhere in the middle, neither preferring pure bound states, nor effective
meson-meson physics with only coupling constants and possibly form factors. As a matter of fact, apart from a few exceptions,
like pions and kaons, Nature does not allow us to study mesonic bound states of any kind, which is equivalent to saying that
such states do not really exist. Hence, instead of extrapolating from pions and kaons to the remainder of the meson family,
it is more democratic to consider pions and kaons mesonic resonances that happen to come out below the lowest threshold for
strong decay. Nevertheless, confinement is an important ingredient for understanding the many regularities observed in mesonic
spectra. Therefore, excluding quark degrees of freedom is also not the most obvious way of describing mesons in general, and
scalars and axial-vectors in particular. 相似文献
53.
CCD光谱谱线标定方法研究 总被引:9,自引:5,他引:4
CCD作为光谱分析和测色仪器的光谱接收器件 ,光谱谱线定位受单色仪狭缝和CCD光敏元尺寸影响。提出采用最小二乘法做曲线拟合和质心法来确定光谱线在CCD上的精确定位 ,使光谱谱线的定位精度得到提高 ,并且不受CCD光敏元尺寸限制。实验结果表明 ,两种方法对光谱线的定位 ,具有重复性高 ,稳定性好等特点。在定位精度上 ,两者具有一致性。 相似文献
54.
55.
S Uma Sankar 《Pramana》2006,67(4):655-663
In this talk I review the physics possible at India-based Neutrino Observatory (INO). I discuss the improvement in the precision
of currently known quantities and the possibility measuring the presently unknown quantities. 相似文献
56.
T. Rietmann S. Sohn M. Schröder D. Lipinsky H.F. Arlinghaus 《Applied Surface Science》2006,252(19):6640-6643
In order to improve quantification of high mass ions, the influence of cluster composition on detection efficiencies has been studied using a TOF-SIMS IV with the extended capability of postaccelerating ions up to 20 keV. In this experimental study, we focus on the comparison of detection efficiencies for three types of negatively charged secondary cluster ions: gold-alkanethiolate-clusters (AuxMy), gold-sulfur-clusters (AuxSy) and gold-clusters (Aux). The clusters were sputtered from self-assembled monolayers of hexadecanethiols on gold substrates using 10 keV Ar+ primary ions. The detection efficiencies were derived on the basis of a function for the secondary electron yield and a fourth-order approximated Poisson probability distribution for electron propagation and amplification within the microchannel plate.In addition to the well-known dependence of detection efficiencies on ion mass and energy, which has already been studied for positively charged ions, we were able to show a similar behaviour for the investigated negatively charged secondary ions. We have observed major variations among the three types of clusters at similar mass and energy as predicted in a theoretical approach. The observed differences are due to the different composition of the investigated clusters which has a major influence on the kinetic ion induced electron emission within the microchannel plate. For the first time it was possible to experimentally verify these predictions for detection efficiencies. 相似文献
57.
Satya Prakash 《Pramana》1989,33(1):109-131
This article summarizes the recent radiochemical investigations on mass, charge kinetic energy and fragment angular distributions
in low energy fission of actinides. 相似文献
58.
In this note we study constant mean curvature surfaces in asymptotically flat 3-manifolds. We prove that, outside a given compact subset in an asymptotically flat 3-manifold with positive mass, stable spheres of given constant mean curvature are unique. Therefore we are able to conclude that the foliation of stable spheres of constant mean curvature in an asymptotically flat 3-manifold with positive mass outside a given compact subset is unique.
59.
60.
Based on the Dyson-Schwinger equations of QCD in the "rainbow" approximation, the fully dressed quarkpropagator Sf(p) is investigated, and then an algebraic parametrization form of the propagator is obtained as a solutionof the equations. The dressed quark amplitudes Af and Bf built up the fully dressed quark propagator and the dynamicalrunning masses Mf defined by Af and Bf for light quarks u, d and s are calculated, respectively. Using the predictedrunning masses Mf, quark condensates <0|q(0)q(0)|0> = -(0.255 GeV)a for u, d quarks, and <0|s s|0> = 0.8<0|q(0)q(0)]0)for s quark, and experimental pion decay constant fπ = 0.093 GeV, the masses of Goldstone bosons K, π, and η are alsoevaluated. The numerical results show that the masses of quarks are dependent on their momentum p2. The fully dressedquark amplitudes Af and Bf have correct behaviors which can be used for many purposes in our future researches onnonperturbative QCD. 相似文献