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971.
Akikazu Matsumoto Sachiyo Umehara Hiroyuki Watanabe Takayuki Otsu 《Journal of Polymer Science.Polymer Physics》1993,31(5):527-535
Poly(N-n-butylitaconimide) was prepared by radical polymerization in benzene and in bulk at 60°C and was subsequently fractionated at 30°C with benzene and methanol as solvent and nonsolvent, respectively. Relationships between molecular weight and intrinsic viscosity (Mark-Houwink-Sakurada equations) in tetrahydrofuran, benzene, and toluene at 30°C are established. From the Burchard-Stockmayer-Fixman plot, the characteristic ratio of this polymer is determined, and local chain conformation is discussed in relation to the termination process in radical polymerization. © 1993 John Wiley & Sons, Inc. 相似文献
972.
973.
Teik-Cheng Lim 《Journal of mathematical chemistry》2007,42(1):93-101
This paper tests the validity of a Lennard–Jones-type and Morse-type potential functions, consisting a combination of pi and
golden ratio constants, for describing intermolecular and interatomic interaction energy. The adjustable parameter, n, can be obtained based on experimental data near the minimum well-depth or by parametric conversion from other established
potential functions. The remarkably good correlation of the proposed potential functions with experimental data and other
potential functions reveal an intriguing property of the relationship between pi and golden ratio within the context of chemistry. 相似文献
974.
Hélène Pellissier Author Vitae 《Tetrahedron》2007,63(16):3235-3285
975.
Jens S. Frederiksen Kim S. Larsen John Noga Patchrawat Uthaisombut 《Journal of Algorithms in Cognition, Informatics and Logic》2003,48(2):407
When messages, which are to be sent point-to-point in a network, become available at irregular intervals, a decision must be made each time a new message becomes available as to whether it should be sent immediately or if it is better to wait for more messages and send them all together. Because of physical properties of the networks, a certain minimum amount of time must elapse in between the transmission of two packets. Thus, whereas waiting delays the transmission of the current data, sending immediately may delay the transmission of the next data to become available even more. We propose a new quality measure and derive optimal deterministic and randomized algorithms for this on-line problem. 相似文献
976.
The study aims to exploit incremental analysis or marginal analysis to overcome the drawbacks of ratio scales utilized in various multi-criteria or multi-attribute decision making (MCDM/MADM) techniques. In the proposed 11-step procedure, multiple criteria of alternatives are first reorganized as two categories – benefits and costs – and decision information will be manipulated separately. The performances of alternatives are then evaluated on their incremental benefit–cost ratio, and the rank can be obtained by applying the group TOPSIS (technique for order preference by similarity to ideal solution) model (Shih et al., 2007). Two representations of cost, i.e., a cost index and utility index, are proposed in the model to better-fit real-world situations. In addition, some considerations on costs and input–output relations are also discussed in order to understand the essentials of incremental analysis. In the final part, a case of robot selection demonstrates the suggested model to be both robust and efficient in a group decision-making environment. 相似文献
977.
本文研究一类具有特殊工件的平行机在线排序问题,目标是最小化最大完工时间.此模型有两种工件:正常工件和特殊工件.正常工件能够在m台平行机的任何一台机器上加工,而特殊工件仅能够在它唯一被指定的机器上加工.文中所有特殊工件的指定机器为M1.我们提供了竞争比为(2m2-2m 1)/(m2-m 1)的在线近似算法.当m=2时,算法是最好可能的.当m=3时,算法的竞争比为13/7≈1.857,并且提供了竞争比的下界(1 (平方根33))14≈1.686. 相似文献
978.
Liming Cai Xuezhi Li Jingyuan Yu Guangtian Zhu 《Mathematical Methods in the Applied Sciences》2008,31(7):859-877
In this paper, a ratio‐dependent predator–prey model with stage structure and harvesting is investigated. Mathematical analyses of the model equations with regard to boundedness of solutions, nature of equilibria, permanence and stability are performed. By constructing appropriate Lyapunov functions, a set of easily verifiable sufficient conditions are obtained for the global asymptotic stability of nonnegative equilibria of the model. The existence possibilities of bioeconomic equilibria have been examined. An optimal harvesting policy is also given by using Pontryagin's maximal principle. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
979.
Wen‐Yang Chang Te‐Hua Fang Yu‐Cheng Lin 《Journal of Polymer Science.Polymer Physics》2008,46(10):949-958
The thermomechanical and optical characteristics of polyvinylidene fluoride (PVDF) are investigated using a thermomechanical, a nanoindentation, anda photometric analyzer for flexible electronic applications. Experimental results show that thermomechanical characteristics, thermal elongation, and expansion, are greatly influenced at stretching ratios of over four in the stretching direction. Consequently, shrinking occurs because of higher cohesion at the tie chains of the amorphous regions. Additionally, there are almost uniform hardness and Young's modulus of about 0.25 ± 0.01 and 3.44 ± 0.14 GPa when the penetration depth is about 1000 nm. Unstretched PVDF films have a higher absorbance in the ultraviolet light range than stretched films do. PVDF films stretched over three times their original length have transmittance of above 90% at near infrared light. In addition, PVDF films stretched at lower temperatures show a lower transmittance because the films easily whitened during α to β phase transformations. The results provide information to optimize PVDF films for applications in flexible designs. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 949–958, 2008 相似文献
980.
L. S. Ettre 《Journal of separation science》1985,8(9):497-503
This paper briefly surveys three important considerations related to the tube diameter and film thickness. These are the interrelationship of these two parameters through the phase ratio, the different meanings of the term “efficiency”, and the influence of film thickness and tube diameter on sample capacity. Comparative examples are given for columns having different diameters and film thicknesses. 相似文献