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11.
12.
Alec M. Lee 《The Journal of the Operational Research Society》1983,34(8):753-763
The British still excel in agriculture just as, a century or so ago, they did in manufacturing and, 30 years ago, in computing. The Japanese, who are also good at agriculture, came to excel in manufacturing and probably now lead the world in information technology. Now Britain is trying to catch up. The paper presents some views of the situation. 相似文献
13.
Dongkwan Kim Alec B. Scranton Jeffrey W. Stansbury 《Journal of polymer science. Part A, Polymer chemistry》2009,47(5):1429-1439
We investigated the formation of ground‐state donor/acceptor complexes between xanthene dyes [rose bengal (RB) and fluorescein (FL)] and a diphenyliodonium (DPI) salt, which is dissolved in 2‐hydroxyethyl methacrylate (HEMA) monomer. To characterize the association constant of the complex, we have suggested a new analysis model based upon the Benesi–Hildebrand model. Because the assumption of the original Benesi–Hildebrand model is that the absorption bands are only due to the presence of the complex and that the absorption by the free component is negligible, the model cannot be applied to our systems, which is a dye‐based initiator system. For each dye, the molar absorptivity of the ground‐state complex was evaluated as a function of wavelength, and this analysis confirmed the validity of the modified Benesi–Hildebrand model. In addition, we observed that the RB/DPI photoinitiator system failed to produce a perceptible polymerization rate but the FL/DPI photoinitiator system provided high rates of polymerization. On the basis of the association constant for these complexes, we concluded that the observed kinetic differences arise from the different association constant values of the ground‐state dye‐acceptor complex, resulting in back‐electron transfer reaction. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1429–1439, 2009 相似文献
14.
Alec Stephenson 《Extremes》2003,6(1):49-59
Methods are given for simulating from symmetric and asymmetric versions of the multivariate logistic distribution, and from other multivariate extreme value distributions based on the well known logistic model. We consider two general approaches. The first approach uses transformations to derive random variables with a joint distribution function from which it is easy to simulate. The second approach derives from a specification of conditionally independent marginal components, conditioning on positive stable random variables. This specification extends to models of nested or hierarchical type and leads to an efficient way of incorporating marginal censoring. The algorithms presented in Sections 2 and 3 are available on request from the author. They are also included in the R (Ihaka and Gentleman, 1996) package evd (Stephenson, 2002), which is available from http://www.maths.lancs.ac.uk/~stephena/. 相似文献
15.
One possible solution to mitigating the effects of high atmospheric concentrations of carbon dioxide (CO2) is the use of a plasma source to break apart the molecule into carbon monoxide (CO) and oxygen. This work experimentally
investigates the efficiency of dissociation of CO2 in a 1-kW radio-frequency (rf) plasma source operating at 13.56-MHz in a low-pressure discharge. Mass spectrometry diagnostics
are used to determine the species present in the discharge, and these measurements are used to calculate the energy efficiency
and conversion efficiency of CO2 dissociation in the rf plasma source. Experimental results have found that the conversion efficiency of CO2 to CO can reach values near 90%, however energy efficiency reaches a maximum of 3%. A theoretical energy cost analysis is
also given as a method to evaluate the effectiveness of any plasma system designed for CO2 emissions reduction. 相似文献
16.
An efficient stereoselective synthesis of norcembrenolide B (8) and scabrolide D (9) is reported. The strategy is inspired by biogenetic relationships of related cembrenoids. Central to this approach is the construction of norbipinnatin J which upon selective C2 deoxygenation and C8 oxygenation produces norrubifolide and norcoralloidolide A. A sequence of site-selective oxidations and skeletal reorganizations then yields, in a divergent manner, compounds 8 and 9. The studies allow revision of the proposed structure of scabrolide D (9), which is identical to norcembrenolide C. 相似文献
17.
In this paper we present a new framework for identifying preferred solutions to multi-objective binary optimisation problems.
We develop the necessary theory which leads to new formulations that integrate the decision space with the space of criterion
weights. The advantage of this is that it allows for incorporating preferences directly within a unique binary optimisation
problem which identifies efficient solutions and associated weights simultaneously. We discuss how preferences can be incorporated
within the formulations and also describe how to accommodate the selection of weights when the identification of a unique
solution is required. Our results can be used for designing interactive procedures for the solution of multi-objective binary
optimisation problems. We describe one such procedure for the multi-objective multi-dimensional binary knapsack formulation
of the portfolio selection problem. 相似文献
18.
Quinto-Hernandez A Wodtke AM Bennett CJ Kim YS Kaiser RI 《The journal of physical chemistry. A》2011,115(3):250-264
Methyl azide (CH(3)N(3)) might be a potential precursor in the synthesis of prebiotic molecules via nonequilibrium reactions on interstellar ices initiated by energetic galactic cosmic rays (GCR) and photons. Here, we investigate the effects of energetic electrons as formed in the track of cosmic ray particles and 193 nm photons with solid methyl azide at 10 K and the inherent formation of methanimine (CH(2)NH), hydrogen cyanide (HCN), and hydrogen isocyanide (HNC). We present a systematic kinetic study and outline feasible reaction pathways to these molecules. These processes might be also important in solar system analogue ices. 相似文献
19.
Curt DeCaro Vidanage Nuwan Karunaratne Sambhunath Bera Laurence B. Lurio Alec R. Sandy Suresh Narayanan Mark Sutton John Winans Kirk Duffin Jon Lehuta Nicholas Karonis 《Journal of synchrotron radiation》2013,20(2):332-338
The technique of speckle visibility spectroscopy has been employed for the measurement of dynamics using coherent X‐ray scattering. It is shown that the X‐ray contrast within a single exposure can be related to the relaxation time of the intermediate scattering function, and this methodology is applied to the diffusion of 72 nm‐radius latex spheres in glycerol. Data were collected with exposure times as short as 2 ms by employing a resonant shutter. The weak scattering present for short exposures necessitated an analysis formalism based on the spatial correlation function of individual photon charge droplets on an area detector, rather than the usual methods employed for intensity correlations. It is demonstrated that this method gives good agreement between theory and experiment and thus holds promise for extending area‐detector‐based coherent scattering methods to the study of faster dynamics than previously obtainable. 相似文献
20.
Alec M. Lee 《The Journal of the Operational Research Society》1979,30(11):975-979
Since computers first appeared commercially in the early 1950's they have been exploited with some success (and some failures) in the execution of low-level, administrative and business routines. They have proven of great benefit in scientific and engineering computation. But, despite early promises, senior managers have personally had little help from their application. Some reasons for this disappointing experience are inherent in the available technology. It is forecast that emerging new hardware, software and communications techniques and products will create a new information technology in the 1980's which will not possess the defects and limitations which senior managements have so far both perceived and experienced. 相似文献