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1.
The definition is stated for a catalytic test working at constant total pressure. The hydrogenation of 1-hexene has been studied with organoiridium compounds as catalysts. Of the derivatives [IrCl(cod)PR3], the compound with PR3 = tricyclohexylphosphine (PCy3) has shown an activity and a selectivity superior to those of previously known catalysts.Two kinetic domains are found according to the temperature. Above ?10°C, the reaction is first order in hydrogen, one-third order in catalyst and zero order in 1-hexane. Below ?10°C it is first order in hydrogen, one-half order in catalyst and one-third order in 1-hexane.The optimum ratio PCy3/Ir is 1 instead of 2, the value commonly found for other phosphine ligands.Other interesting catalysts containing acetato ligands are described. 相似文献
2.
It is shown that oxazolidines derived from racemic unbranched α-acetoxyaldehydes and ?-ephedrine have predictable chromatographic mobilities, with the R-isomer always having a higher Rf-value. This resolution has been used to prepare and -HETE. 相似文献
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A new, one-step preparation of 1,4-di(2,2':6',2' '-terpyridin-4'-yl)benzene was employed in the synthesis of a linear trinuclear Ru(II) complex, which was compared to mononuclear and dinuclear analogues using UV-vis spectrometry, cyclic voltammetry, and ability to sensitize the photogeneration of methyl viologen radical cation. The chain length-dependent increase in sensitization ability was consistent with an increasing molar absorbance and with an end-on approach of the photoreactants mitigating the increasing charge. 相似文献
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Potvin Alfred R. Crosier William G. Fromm Eli Lin James C. Neuman Michael R. Pilkington Theo C. Robinson Charles J. Schneider Lawrence W. Strohbehn John W. Szolovits Peter Tompkins Willis J. 《IEEE transactions on bio-medical engineering》1986,(1):48-59
MORE than 200 years ago, our forefathers made note of man's inalienable rights to life, liberty, and the pursuit of happiness. To the engineering community (applied science in the service of man), these may be coincident with applications to medicine and biology (biomedical engineering), defense, and entertainment. Biomedical engineering research has the distinction, among these three missions, of not only contributing to the quality of human life through the industrial economy but also to life itself?the most fundamental concern of all people. It is through biomedical engineering research that we have been able to learn much concerning the functioning of living systems, and it is through such knowledge that we have been able to develop improved clinical diagnosis, monitoring, and treatment, including life-sustaining devices and aids to the handicapped. Each step represents an improvement in the quality of life, and each step forms the foundation upon which to gain new knowledge to improve upon earlier developments. 相似文献
7.
Yu Shen Jean-Yves Potvin Jean-Marc Rousseau Serge Roy 《Annals of Operations Research》1995,61(1):189-211
In this paper, we describe an expert consulting system for a dispatcher working in a courier service company. The system integrates interactive-graphic features and a learning module to support the dispatcher in his(her) task, and to suggest appropriate decisions when new requests come in. An experiment with a professional dispatcher is also reported. 相似文献
8.
Several algorithms to solve the generalized fractional program are summarized and compared numerically in the linear case. These algorithms are iterative procedures requiring the solution of a linear programming problem at each iteration in the linear case. The most efficient algorithm is obtained by marrying the Newton approach within the Dinkelbach approach for fractional programming. 相似文献
9.
An exact algorithm for a vehicle routing problem with time windows and multiple use of vehicles 总被引:2,自引:0,他引:2
Nabila Azi Michel Gendreau Jean-Yves Potvin 《European Journal of Operational Research》2010,202(3):756-763
The vehicle routing problem with multiple use of vehicles is a variant of the classical vehicle routing problem. It arises when each vehicle performs several routes during the workday due to strict time limits on route duration (e.g., when perishable goods are transported). The routes are defined over customers with a revenue, a demand and a time window. Given a fixed-size fleet of vehicles, it might not be possible to serve all customers. Thus, the customers must be chosen based on their associated revenue minus the traveling cost to reach them. We introduce a branch-and-price approach to address this problem where lower bounds are computed by solving the linear programming relaxation of a set packing formulation, using column generation. The pricing subproblems are elementary shortest path problems with resource constraints. Computational results are reported on euclidean problems derived from well-known benchmark instances for the vehicle routing problem with time windows. 相似文献
10.
S. Huang K. J. M. Moriarty E. Myers J. Potvin 《Zeitschrift fur Physik C Particles and Fields》1991,50(2):221-236
We present an initial study of the thermodynamics of hot lattice QCD using the “density of states” method, which we describe in detail. The raw data were generated from a Monte Carlo simulation of pureSU(3) gauge theory on 83×N t lattices, withN t =2,4,8, at several values of the gauge coupling β. These data, taken at up to eight values of β, are then used to reconstruct the “density of states” as a function of the action and one additional observable. When combined with the proper Boltzmann weight this yieldscurves of quantities of interest as functions of the coupling constant β. These curves then yield the equation of state in a range of temperature, and the corresponding velocity of sound is obtained through appropriate derivatives. We also discuss in detail the errors, limitations, and advantages of the density of states method in its general application to QCD. 相似文献