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991.
We propose and demonstrate a simple approach to lower the thermal quenching
effect and improve the output power of Cr:LiSAF lasers, which is
accomplished by employing two laser rods. The resonator contains two laser
rods and is designed by using two ``X' folding cavities in cascade. A tunable
laser output of $\sim $ 180\,mW has been achieved with the pump of single-striped
laser diodes. Compared with lasers using single gain rod, the laser with
dual rods shows less severe thermal effect and increases the output by more
than two times. 相似文献
992.
在拼接点达到GC~2连续的双二次曲线与样条的构造 总被引:2,自引:0,他引:2
本文研究了连续的双二次曲线 ,给出双二次曲线样条的构造方法 .本方法适用在一些特定点上给定相对曲率并要求整个样条曲线 GC2连续的一类问题 ,采用双二次曲线样条得到的样条曲线具有较好保凸性能 . 相似文献
993.
Interior-point methods for semidefinite optimization have been studied intensively in recent times, due to their polynomial complexity and practical efficiency. In this paper, first we present some technical results about symmetric matrices. Then, we apply these results to give a unified analysis for both large update and small update interior-point methods for SDP based on the Nesterov–Todd (NT) direction. 相似文献
994.
Levent Tunçel 《Foundations of Computational Mathematics》2001,1(3):229-254
We generalize primal—dual interior-point methods for linear programming (LP) problems to the convex optimization problems
in conic form. Previously, the most comprehensive theory of symmetric primal—dual interior-point algorithms was given by Nesterov
and Todd for feasible regions expressed as the intersection of a symmetric cone with an affine subspace. In our setting, we
allow an arbitrary convex cone in place of the symmetric cone. Even though some of the impressive properties attained by Nesterov—Todd
algorithms are impossible in this general setting of convex optimization problems, we show that essentially all primal—dual
interior-point algorithms for LP can be extended easily to the general setting. We provide three frameworks for primal—dual
algorithms, each framework corresponding to a different level of sophistication in the algorithms. As the level of sophistication
increases, we demand better formulations of the feasible solution sets. Our algorithms, in return, attain provably better
theoretical properties. We also make a very strong connection to quasi-Newton methods by expressing the square of the symmetric
primal—dual linear transformation (the so-called scaling) as a quasi-Newton update in the case of the least sophisticated
framework.
August 25, 1999. Final version received: March 7, 2001. 相似文献
995.
求解约束优化问题的一个对偶算法 总被引:3,自引:0,他引:3
1.引言 考虑下述形式的不等式约束优化问题:其中 =0,1,…,m,是连续可微函数.求解(1.1)的数值方法有很多,传统方法有乘子法,序列一次规划方法,等等(见 Bertsekas(1982), Han(1976, 1977)).近年来对求解(1.1)的原始-对偶算法的研究已成为非线性规划领域的新的热点,如EI-Bakry,Tapia,Tsuchiya & Zhang(1996),Yamashita(1992,1996,1997)等;尽管这些原始-对偶算法具有好的收敛性质和计算效果,但其算法结构相对… 相似文献
996.
Ronald Ouwerkerk Paul A. Bottomley 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2001,148(2):425
This article replies to Spencer et al. (J. Magn. Reson.149, 251–257, 2001) concerning the degree to which chemical exchange affects partial saturation corrections using saturation factors. Considering the important case of in vivo31P NMR, we employ differential analysis to demonstrate a broad range of experimental conditions over which chemical exchange minimally affects saturation factors, and near-optimum signal-to-noise ratio is preserved. The analysis contradicts Spencer et al.'s broad claim that chemical exchange results in a strong dependence of saturation factors upon M0's and T1 and exchange parameters. For Spencer et al.'s example of a dynamic 31P NMR experiment in which phosphocreatine varies 20-fold, we show that our strategy of measuring saturation factors at the start and end of the study reduces errors in saturation corrections to 2% for the high-energy phosphates. 相似文献
997.
998.
IntroductionAsymplecticsystematicmethodology[1- 3]forelasticitywasestablishedbyZhongWan_xie .Hepresentedcreativelythedualvectorsandthesymplecticorthogonalrelationshipandopenedaworkplatformparalleledtothetraditionalelasticity[4 - 9].AnewdualvectorandanewdualdifferentialmatrixLwerepresentedforasymplecticsystematicmethodologyfortwo_dimensionalelasticityandaneworthogonalrelationshipwasdiscoveredforisotropicplaneproblems[4 ]byLuoJian_hui.Theneworthogonalrelationshipisgeneralizedfororthotropicelas… 相似文献
999.
1000.
In [12], A. Pasini and S. Yoshiara studied the distance regular graphs constructed from the Yoshiara dual hyperovals. In this note, we prove that the incidence graphs of the semibiplanes constructed from dimensional dual hyperovals are distance regular graphs if the dual hyperovals are doubly dual hyperovals (DDHOs). This generalizes the result in [12]. 相似文献