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981.
It is shown thatU
*, the adjoint of Koopman's isometric operatorUf(x) =f(Tx) corresponding to the mapTx=x
–1 (mod 1) of the unit interval, is isomorphic to a symmetric integral operator when restricted to a Hilbert space of holomorphic functionsf This result, also obtained by Babenko in a different setting, allows us to derive new trace formulas. Using generalized Temple's inequalities, we determine the relaxation time of the above system with great accuracy. In contrast to a widespread belief, it appears to be unrelated to the entropy of the mapT. 相似文献
982.
本文研究了一类复合型幂级数展开式,证明了一个收敛性定理并举例说明其应用.在注记中指出了可进一步研究的问题. 相似文献
983.
Timothy E. Burrow Raul G. Enriquez William F. Reynolds 《Magnetic resonance in chemistry : MRC》2009,47(12):1086-1094
The effect of various acquisition and processing parameters on the sensitivity of HMBC spectra for typical organic molecules has been systematically investigated. For molecules in the 200–600 molecular weight range, an acquisition time of 0.2 to 0.4 s, a recycle time of no more than 1.0 s, optimization for nJCH = 8 Hz and 512 time increments (with two‐ to fourfold linear prediction) are recommended. Some form of sine bell weighting along f2 and either Gaussian or sine bell weighting along f1 is suggested. The use of a 0.1‐s acquisition time and/or Gaussian or exponential weighting along f2 can result in dramatic sensitivity loss, particularly for correlation peaks involving protons with complex splitting patterns, and should be avoided. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
984.
985.
J. Betzabe Gonzlez‐campos Evgen Prokhorov Gabriel Luna‐Brcenas A. Mendoza Galvn Isaac C. Sanchez Sergio M. Nuo Donlucas B. Garcia‐Gaitan Yuriy Kovalenko 《Journal of Polymer Science.Polymer Physics》2009,47(9):932-943
Relaxations in chitin have been investigated in the temperature range 298–523 K using impedance spectroscopy in the frequency range 10−1–108 Hz. The objective was to detect a glass‐transition temperature for this naturally occurring, semicrystalline polysaccharide. The impedance study was complemented with X‐ray diffraction, thermogravimetric, and differential scanning calorimetry measurements. Preliminary impedance data treatment includes the subtraction of the dc conductivity contribution, the exclusion of contact and interfacial polarization effects, and obtaining a condition of minimum moisture content for further analysis. When all these aspects are taken into account, two relaxations are clearly revealed in the impedance data. For the first time, evidence is presented for a relaxation process, which exhibits a non‐Arrhenius temperature dependence, in dry α‐chitin (∼0.1% moisture content), and likely represents the primary α‐relaxation. This evidence suggests a glass transition temperature for chitin of 335 ± 10 K estimated on the basis of the temperature dependence of the conductivity and of the relaxation time. A second relaxation in dry α‐chitin, not previously reported in the literature, is observed from 353 K to the onset of thermal degradation (∼483 K) and is identified as the σ‐relaxation often associated with proton mobility. It exhibits a normal Arrhenius‐type temperature dependence with activation energy of 113 ± 3 kJ/mol. The latter has not been previously reported in the literature. A high frequency secondary β‐relaxation is also observed with Arrhenius activation energy of 45 ± 1 kJ/mol. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 932–943, 2009 相似文献
986.
曲世亨 《广东微量元素科学》2001,8(3):50-52
阐述了一例胃底溃疡型腺癌伴周边器官淋巴组织广泛转移患者,行“贲门MT术”姑息治疗后,经九个月大剂量多种微量元素制剂补充达到很好的临床效果。 相似文献
987.
在正项级数Gauss判别法的基础上,定义了正数列an的Gauss指标G=lim[n ln(an/an+1)-1]ln n.从而得到了正项级数的Gauss指标判别法.通过具体计算已有各种判别法的Gauss指标,结果表明,Gauss指标判别法是达朗贝尔、柯西、拉贝、高斯和Bertrand等5种判别法的推广. 相似文献
988.
O. Carja 《Journal of Optimization Theory and Applications》2000,105(2):285-297
The present paper is concerned with the study of the Hamilton–Jacobi–Bellman equation for the time optimal control problem associated with infinite-dimensional linear control systems from the point of view of continuous contingent solutions. 相似文献
989.
We are interested in the problem of scheduling orders for different product types in a facility with a number of machines
in parallel. Each order asks for certain amounts of various different product types which can be produced concurrently. Each
product type can be produced on a subset of the machines. Two extreme cases of machine environments are of interest. In the
first case, each product type can be produced on one and only one machine which is dedicated to that product type. In the
second case, all machines are identical and flexible; each product type can be produced by any one of the machines. Moreover,
when a machine in this case switches over from one product type to another, no setup is required. Each order has a release
date and a weight. Preemptions are not allowed. The objective is minimizing the total weighted completion time of the orders.
Even when all orders are available at time 0, both types of machine environments have been shown to be NP-hard for any fixed
number (≥2) of machines. This paper focuses on the design and analysis of approximation algorithms for these two machine environments.
We also present empirical comparisons of the various algorithms. The conclusions from the empirical analyses provide insights
into the trade-offs with regard to solution quality, speed, and memory space.
Electronic Supplementary Material The online version of this article () contains supplementary material, which is available to authorized users.
This research is supported by the National Science Foundation through grants DMI-0300156 and DMI-0245603. 相似文献
990.
使用MTV模型与Morkowitz证券组合选择模型的投资决策系统 总被引:1,自引:0,他引:1
利用期望和方差的秩系数法、MTV模型、Morkowitz证券组合选择模型构造了一实用的投资决策系统. 相似文献