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991.
992.
一种新的两道工序柔性流水车间排序问题 总被引:1,自引:0,他引:1
本文针对F_2(p),h11.1|m_1=1,m_2=μ≥2|C_(max)这一问题给出了几种近似算法,并对每种近似算法进行了最坏情形分析,给出了最坏情形界. 相似文献
993.
994.
Yuhui Wei Junquan He Hongyan Qin Xin'an Wu Xiaojun Yao 《Biomedical chromatography : BMC》2009,23(10):1116-1120
Ferruginol, a diterpene phenol, has recently received attention for its extensive pharmacological properties, including anti‐tumor, antibacterial, cardio‐protective and gastroprotective effects. In the present study, a high‐performance liquid chromatographic (HPLC) method was developed for determination of ferruginol in rat plasma and applied for the pharmacokinetics study. The HPLC assay was performed with a VP ODS‐C18 column. The mobile phaseconsisted of methanol and 1% acetic acid solution (90:10, v/v). The flow rate was 1.0 mL/min, and the wavelength was set at 270 nm. This method was linear over the studied range of 0.1–10.0 µg/mL for ferruginol. The correlation coefficient was 0.9998. The intra‐day and inter‐day precisions were better than 4 and 5%, respectively. The extraction recovery and accuracy were greater than 97 and 96%, respectively. The detection limit was 30 ng/mL. The mean maximum concentration of ferruginol in rat plasma was 3.14 µg/mL at 40 min after oral administration at a dose of 20 mg/kg. Ferruginol was absorbed quickly p.o. with t1/2ka = 14.86 min and had a high rate of elimination with t1/2 = 41.73 min. The pharmacokinetic process of ferruginol in rat was well described with a one‐compartment model. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
995.
This paper describes the design principles of a fluid-based, discrete-event simulator and its application to the characterization of losses in ATM networks. This simulation technique allows us to obtain performance measures that either cannot be found using known analytical methods or for which a conventional simulation is too expensive; notably, fluid-model simulation makes it feasible to characterize for a given buffer its occupation, duration of congestion periods, frequency of loss bursts and loss-burst volume in fairly complex networks. Several numerical examples illustrate the proposed simulation method. 相似文献
996.
We present a theoretical analysis of the noise performance of phase measuring feedback interferometers. We first analyse the operation of this kind of instrument and note that under certain circumstances bistability can occur. The bistable region should be avoided if possible when using feedback interferometry for high-accuracy measurement with low-input powers, as it can give rise to very high-noise levels. We then go on to investigate the effects of shot noise (on the interferometer output signal) and thermal noise (in the feedback loop), and relate these to the phase measurement accuracy of the interferometer. A ‘best-case’ calculation indicates that phase noise of about 0.005λ is possible at input powers in the nanowatt region. In practice, we expect that noise levels will be higher than predicted (particularly at high-input powers) due to the effects of vibration and air turbulence. 相似文献
997.
998.
999.
Tammam Benmusa David J. Parish Mark Sandford 《International Journal of Communication Systems》2005,18(2):159-177
Network performance monitoring is essential for managing a network efficiently and for ensuring reliable operation of the network. Monitored network performance changes reflect events in the network, such as faults, significant changes in usage patterns or planned alterations. Network managers are interested in how and when the performance of a network changes; however it is inefficient to analyse all the data resulting from the monitoring operation manually. In this paper a rule based algorithm to automate detection of the changes in one of the network performance parameters, namely delay, is presented and described in detail. The nature of the delay pattern in a commercial communication network was the key issue in developing this algorithm. The approach was tested with monitored delay data generated from three different networks and showed good results. Also, the algorithm was tested with sets of delay data which have been already input to a previously developed detector based on a different approach, and the results between the two detectors are compared. In addition to a noticeable improvement in detection performance, the new approach provides more generality and independency of the source of the delay data, making the approach generally applicable to other networks. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
1000.
Construction of parametric biorthogonal wavelet filter banks with two parameters for image coding 总被引:1,自引:0,他引:1
We had presented a simple technique, which is based on the theory of Diophantine equation, for parametrization of popular
biorthogonal wavelet filter banks (BWFBs) having the linear phase and arbitrary multiplicity of vanishing moments (VMs), and
constructed a type of parametric BWFBs with one free parameter [15]. Here we generalize this technique to the case of two
parameters, and construct a type of parametric BWFBs with two free parameters. The closed-form parameter expressions of the
BWFBs are derived, with which any two-parameter family of BWFBs having preassigned VMs can be constructed, and six families,
i.e., 9/11, 10/10, 13/11, 10/14, 17/11, and 10/18 families, are considered here. Two parameters provide two degrees of freedom
to optimize the resulting BWFBs with respect to other criteria. In particular, in each family, three specific rational-coefficient
BWFBs with attractive features are obtained by adjusting the parameters: the first is not only very close to a quadrature
mirror filter (QMF) bank, but has optimum coding gain; the second possesses characteristics that are close to the irrational
BWFB with maximum VMs by Cohen et al.; and the last which has binary coefficients can realize a multiplication-free discrete
wavelet transform. In addition, two BWFBs are systematically verified to exhibit performance competitive to several state-of-the-art
BWFBs for image compression, and yet require lower computational costs.
This work was supported by the Natural Science Foundation of Jiangsu province, China under Grant 07KJD520005. 相似文献