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81.
A threshold start-up policy is appealing for manufacturing (service) facilities that incur a cost for keeping the machine
(server) on, as well as for each restart of the server from its dormant state. Analysis of single product (customer) systems
operating under such a policy, also known as the N-policy, has been available for some time. This article develops mathematical analysis for multiproduct systems operating
under a cyclic exhaustive or globally gated service regime and a threshold start-up rule. It pays particular attention to
modeling switchover (setup) times. The analysis extends/unifies existing literature on polling models by obtaining as special
cases, the continuously roving server and patient server polling models on the one hand, and the standard M/G/1 queue with N-policy, on the other hand. We provide a computationally efficient algorithm for finding aggregate performance measures, such
as the mean waiting time for each customer type and the mean unfinished work in system. We show that the search for the optimal
threshold level can be restricted to a finite set of possibilities.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
82.
This study describes the application of the electrochemically generated molybdenum‐based catalyst system MoCl5? e?? Al? CH2Cl2 to ring‐opening metathesis polymerization of bicyclo[2.2.1]hept‐2‐ene (norbornene). The results are compared with those previously obtained by the WCl6? e?? Al? CH2Cl2 system. The polymer product has been characterized by 1H and 13C NMR, IR and gel‐permeation chromatography techniques. This molybdenum‐based catalyst system has led to a mainly trans stereoconfiguration (ca 60%) of the double bonds, in contrast to the polymer obtained with the tungsten‐based analogue, where the cis content is 60%. Analysis of the poly(1,3‐cyclopentylenevinylene) microstructure by 13C NMR spectroscopy revealed that the polymer having σc = 0.41 (fraction of double bonds with cis configuration) contains a slightly blocky distribution (rtrc > 1) of the double‐bond dyads (rtrc = 1.44). In addition, the influence of reaction parameters, e.g. reaction time, electrolysis time and catalyst aging time, on conversion has been analysed in detail. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
83.
Microstructure and optical properties of nanocrystalline ZnO and ZnO:(Li or Al) thin films 总被引:1,自引:0,他引:1
Zinc oxide thin films (ZnO, ZnO:Li, ZnO:Al) were deposited on glass substrates by a sol-gel technique. Zinc acetate, lithium acetate, and aluminum chloride were used as metal ion sources in the precursor solutions. XRD analysis revealed that Li doped and undoped ZnO films formed single phase zincite structure in contrast to Al:ZnO films which did not fully crystallize at the annealing temperature of 550 °C. Crystallized films had a grain size under 50 nm and showed c-axis grain orientation. All films had a very smooth surface with RMS surface roughness values between 0.23 and 0.35 nm. Surface roughness and optical band tail values increased by Al doping. Compared to undoped ZnO films, Li doping slightly increased the optical band gap of the films. 相似文献
84.
In this Letter, we present the homotopy perturbation method (shortly HPM) for obtaining the numerical solution of the RLW equation. We obtain the exact and numerical solutions of the Regularized Long Wave (RLW) equation for certain initial condition. The initial approximation can be freely chosen with possible unknown constants which can be determined by imposing the boundary and initial conditions. Comparison of the results with those of other methods have led us to significant consequences. The numerical solutions are compared with the known analytical solutions. 相似文献
85.
Ethyl 1,2-dihydro-4-methylcarbazole-3-carboxylate and 11-methl-6H-pyrido[4,3-b] carbazole (5-demethylellipticine) have been synthesized by different routes. 相似文献
86.
We report the experimental demonstration of a new Raman technique that produces 200 sidebands, ranging in wavelength from 3 microm to 195 nm. By studying multiphoton ionization of nitric oxide (NO) molecules, we show mutual phase coherence among 15 visible sidebands covering 0.63 octaves of bandwidth. 相似文献
87.
We make use of coherent control of four-wave mixing to the ultraviolet as a diagnostic and describe the generation of a periodic optical waveform where the spectrum is sufficiently broad that the envelope is approximately a single-cycle in length, and where the temporal shape of this envelope may be synthesized by varying the coefficients of a Fourier series. Specifically, using seven sidebands, we report the generation of a train of single-cycle optical pulses with a pulse width of 1.6 fs, a pulse separation of 11 fs, and a peak power of 1 MW. 相似文献
88.
We show the existence of discrete sets of Raman sidebands which self-consistently establish a Raman coherence and propagate without change in amplitude and relative phase. Equivalently, there exist periodic femtosecond-time-scale, temporal pulse shapes which propagate without change in shape. 相似文献
89.
We use molecular deuterium and two driving lasers to demonstrate collinear generation of mutually coherent equidistant sidebands, covering 50 000 cm(-1) of spectral bandwidth and ranging from 2.94 microm to 195 nm in wavelength. The essential idea is the adiabatic preparation of a single, highly coherent (|rho(ab)| = 0.33) molecular eigenstate. 相似文献
90.
We demonstrate a type of Raman self-focusing and -defocusing that is inherent in operation at maximum coherence. In this regime the two-photon detuning from the Raman resonance controls the refractive index of the medium. 相似文献