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51.
Hideki Hashimoto Mutsunori Yagiura Shinji Imahori Toshihide Ibaraki 《4OR: A Quarterly Journal of Operations Research》2010,8(3):221-238
Vehicle routing and scheduling problems have a wide range of applications and have been intensively studied in the past half
century. The condition that enforces each vehicle to start service at each customer in the period specified by the customer
is called the time window constraint. This paper reviews recent results on how to handle hard and soft time window constraints,
putting emphasis on its different definitions and algorithms. With these diverse time windows, the problem becomes applicable
to a wide range of real-world problems. 相似文献
52.
Matsumura Y Maki T Murakami S Onomura O 《Journal of the American Chemical Society》2003,125(8):2052-2053
New catalytic ability of copper(II) ion has been exploited for monobenzoylation of 1,2-diols. The catalyst can be readily modified by ligation to acquire higher stereoselectivity. Highly effective kinetic resolution of dl-1,2-diols was achieved. The enantiodiscrimination process was clearly shown to be controlled by the kinetics of acylation of dl-1,2-diols. The catalytic method was successfully applied to asymmetric desymmetrization of meso-hydrobenzoin. 相似文献
53.
Perret F Nishihara M Takeuchi T Futaki S Lazar AN Coleman AW Sakai N Matile S 《Journal of the American Chemical Society》2005,127(4):1114-1115
We report that the efflux of 5(6)-carboxyfluorescein anions from neutral egg yolk phosphatidylcholine vesicles is mediated by oligo/polyarginines only in the presence of activating amphiphilic anions. Screening of anion activators reveals best synergism for amphiphilic carboxylates (fullerene > calix[4]arene approximately coronene > pyrene > calix[6]arene > alkyl), whereas amphiphilic sulfates show less satisfactory activation despite often lower effective concentrations. The analogous alcohols and one calix[4]arene diphosphate were inactive. These results are discussed in the context of a tentative anion carrier mechanism, where interactions with bilayer (interface-directed translocation) and carrier (arene-templated carboxylate-guanidinium pairing) contribute to activator efficiencies. Applied to HeLa cells, pyrenebutyrate is shown to significantly increase the uptake of a fluorescently labeled octaarginine in a concentration-dependent manner. 相似文献
54.
Toshihide Baba Yuki Morikawa Norito Komatsu Toshiro Takahashi Hisashi Sugisawa Yoshio Ono 《Research on Chemical Intermediates》2000,26(1):13-20
The dynamic properties of protons in H-[Ga]-ZSM-5, H-[B]-ZSM-5 and H-[Al-B]-ZSM-5 were compared with that of protons in H-[Al]-ZSM-5
by temperature dependence of 1H MAS NMR in the range of 298 k and 473 K. The temperature dependence of the line width of 1H MAS NMR reveals that protons in H-[Ga]-ZSM-5 were more mobile than those in H-[Al]-ZSM-5 at temperature as low as 373 K.
The protons in H-[B]-ZSM-5 were not mobile at 473 K and fixed in the zeolite frame work as the bridging hydroxyl groups, ≡B-OH-Si≡.
The thermal motion of protons in ≡Al-OH-Si≡ was suppressed by introducing B3+ cations into the framework of H-[Al]-ZSM-5. 相似文献
55.
Three complementary capillary electrophoresis (CE) methods were developed for the separation and quantification of ephedrine and pseudoephedrine stereoisomers. Either single or dual cyclodextrin-based chiral selector systems provided enantioselective separation of the compounds of interest. The three methods were applied to the analysis of a suite of five standard reference materials (SRMs) containing ephedra. Use of a high-sensitivity UV detection cell enhanced quantification of the analytes of interest over the wide range of concentrations encountered in the SRMs. Results for (-)-ephedrine ranged from 0.31 to 76.43 mg/g, and for (+)-pseudoephedrine ranged from 0.049 to 9.23 mg/g in the materials studied. Results from the three methods agreed well with each other and with the results from other methods of analysis. The addition of known amounts of specific enantiomers was used to confirm the enantiomeric identity of the analytes. The results obtained by the three CE methods were utilized for value assignment of the ephedrine alkaloid content of these five SRMs. 相似文献
56.
57.
Satoru Hashizume Masao Fukushima Naoki Katoh Toshihide Ibaraki 《Mathematical Programming》1987,37(3):255-267
We are concerned with a combinatorial optimization problem which has the ratio of two linear functions as the objective function.
This type of problems can be solved by an algorithm that uses an auxiliary problem with a parametrized linear objective function.
Because of its combinatorial nature, however, it is often difficult to solve the auxiliary problem exactly. In this paper,
we propose an algorithm which assumes that the auxiliary problems are solved only approximately, and prove that it gives an
approximate solution to the original problem, of which the accuracy is at least as good as that of approximate solutions to
the auxiliary problems. It is also shown that the time complexity is bounded by the square of the computation time of the
approximate algorithm for the auxiliary problem. As an example of the proposed algorithm, we present a fully polynomial time
approximation scheme for the fractional 0–1 knapsack problem. 相似文献
58.
59.
Toshihide Ibaraki 《Journal of Mathematical Analysis and Applications》1973,43(3):642-693
As finite state models to represent a discrete optimization problem given in the form of an r-ddp (recursive discrete decision process), three subclasses of r-msdp (recursive monotone sequential decision process) are introduced in this paper. They all have a feature that the functional equations of dynamic programming hold and there exists an algorithm (in the sense of the theory of computation) to obtain the set of optimal policies. (In this sense, we may call them solvable classes of discrete dynamic programming.) Besides the algorithms for obtaining optimal policies, two types of representations are extensively studied for each class of r-msdp's. Other related decision problems are also discussed. It turns out that some of them are solvable while the rest of them are unsolvable. 相似文献
60.