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901.
李志中 《新疆大学学报(理工版)》1991,8(1):84-89
根据新疆巴里坤湖晚第四纪沉积的有机质、化学元素分布与古气候关系的讨论,得到如下结论:1.有机质和化学元素分布与生物地层旋回有很好的相关性,表明中纬度内陆干旱区存在着冷湿—暖干的气候格局,这一格局从晚更新世以来即制约着本区地球化学环境的发展。2.在干旱区封闭湖盆,有机质组成和化学元素组合变化主要受有效降水多寡(或湿度)的控制和影响,C/N、Sr/Ba和CaO/MgO比值均反映本区古气候变化具有周期性。3.多数化学元素和CaCO_3含量分布表明本区古气候自更新世以来向着干旱化波动发展。 相似文献
902.
903.
We identify structured collections of multi-class queueing systems whose optimal return (a minimised cost) is a supermodular function of the set of customer classes allowed external access to the system. Our results extend considerably the range of systems for which such a claim can be made. The returns from such systems also exhibit a form of directional convexity when viewed as functions of a vector of arrival rates. Applications to load balancing problems are indicated. 相似文献
904.
905.
Richard H. Byrd Jorge Nocedal Richard A. Waltz 《Computational Optimization and Applications》2003,26(1):35-61
A slack-based feasible interior point method is described which can be derived as a modification of infeasible methods. The modification is minor for most line search methods, but trust region methods require special attention. It is shown how the Cauchy point, which is often computed in trust region methods, must be modified so that the feasible method is effective for problems containing both equality and inequality constraints. The relationship between slack-based methods and traditional feasible methods is discussed. Numerical results using the KNITRO package show the relative performance of feasible versus infeasible interior point methods. 相似文献
906.
关于不等式约束的信赖域算法 总被引:3,自引:0,他引:3
对于具有不等式约束的非线性优化问题,本文给出一个依赖域算法,由于算法中依赖区域约束采用向量的∞范数约束的形式,从而使子问题变二次规划,同时使算法变得更实用。在通常假设条件下,证明了算法的整体收敛性和超线性收敛性。 相似文献
907.
Surface instability of a collisionless semi-infinite current carrying plasma is studied. The semi-infinite plasma bounded
by a plane surface is under the influence of a high frequency (hf) field. There are two classes of surface modes. One is a normal extension of zero high frequency field and the other due
entirely to the presence ofhf field. As expected, with the increase in thehf field, the growth rates of the surface instabilities decrease. There are regions defined by the electron drift velocityu where the unstable surface and bulk regions overlap. The interesting result is that unlike the bulk plasma, there is a stable
region on theu-axis flanked by two unstable regions. The width of this stable region increases with the increase in the field strength. 相似文献
908.
This part is concerned with the applications of the general limit theorems with rates of Part I, achieved by specializing the limiting r.v. X. This leads to new convergence theorems with higher order rates in the one- and multi-dimensional case for the stable limit law, for the central limit theorem, and the weak law of large numbers. 相似文献
909.
N. Rehfeld U. Gerhardt E. Dietz 《Applied Physics A: Materials Science & Processing》1973,1(4):229-232
We use a 0.5 m Seya-Namioka monochromator and two gold plated cylindrical mirrors to set up an optical system which produces
a collimated beam of plane polarized, monochromatic radiation in the vacuum ultraviolet region. The two mirrors compensate
for the astigmatism of the Seya-Namioka monochromator, thereby increasing the spectral resolution drastically. The degree
of linear polarization is about 0.97–1.00 in the spectral region of 6–11.5 eV. 相似文献
910.
Ibrahim A Ahmad 《Journal of multivariate analysis》1979,9(2):314-321
In this note we obtain rates of convergence in the central limit theorem for certain maximum of coordinate partial sums of independent identically distributed random vectors having positive mean vector and a nonsingular correlation matrix. The results obtained are in terms of rates of convergence in the multidimensional central limit theorem. Thus under the conditions of Sazonov (1968, Sankhya, Series A30 181–204, Theorem 2), we have the same rate of convergence for the vector of coordinate maximums. Other conditions for the multidimensional CLT are also discussed, c.f., Bhattachaya (1977, Ann. Probability 5 1–27). As an application of one of the results we obtain a multivariate extension of a theorem of Rogozin (1966, Theor. Probability Appl. 11 438–441). 相似文献