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41.
We consider a single-server queueing system. The arrival process is modelled as a Poisson process while the service times of the consecutive customers constitute a sequence of autoregressive random variables. Our interest into autoregressive service times comes from the need to capture temporal correlation of the channel conditions on wireless network links. If these fluctuations are slow in comparison with the transmission times of the packets, transmission times of consecutive packets are correlated. Such correlation needs to be taken into account for an accurate performance assessment. By means of a transform approach, we obtain a functional equation for the joint transform of the queue content and the current service time at departure epochs in steady state. To the best of our knowledge, this functional equation cannot be solved by exact mathematical techniques, despite its simplicity. However, by means of a Taylor series expansion in the parameter of the autoregressive process, a “light-correlation” approximation is obtained for performance measures such as moments of the queue content and packet delay. We illustrate our approach by some numerical examples, thereby assessing the accuracy of our approximations by simulation. For the heavy correlation case, we give differential equation approximations based on the time-scale separation technique, and present numerical examples in support of this approximation. 相似文献
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Dandurand Jany Samouillan Valérie Lacabanne Colette Pepe Antonietta Bochicchio Brigida 《Journal of Thermal Analysis and Calorimetry》2018,131(2):1323-1332
Journal of Thermal Analysis and Calorimetry - Elastin fibrillogenesis is conditioned by multiple self-assembly processes. Previous studies have evidenced the crucial influence of amino acid... 相似文献
44.
Variability of UV irradiance in Europe 总被引:1,自引:1,他引:0
Seckmeyer G Pissulla D Glandorf M Henriques D Johnsen B Webb A Siani AM Bais A Kjeldstad B Brogniez C Lenoble J Gardiner B Kirsch P Koskela T Kaurola J Uhlmann B Slaper H den Outer P Janouch M Werle P Gröbner J Mayer B de la Casiniere A Simic S Carvalho F 《Photochemistry and photobiology》2008,84(1):172-179
45.
Kerwyn G. Alley Roland Bircher Hans U. Güdel Boujemaa Moubaraki Keith S. Murray Brendan F. Abrahams Colette Boskovic 《Polyhedron》2007
The reaction of Ni(OAc)2, NiX2 (X = Cl, Br) or CoCl2 with the proligand 2-amino-2-methyl-1,3-propanediol (ampdH2) affords a new family of tetranuclear complexes. The syntheses of [Ni4(OAc)4(ampdH)4] (1) and [M4X4(ampdH)4] (M = Ni, X = Cl, 2; M = Ni, X = Br, 3; M = Co, X = Cl, 4) are reported, together with the single crystal X-ray structures of 1, 2 and 4 and the magnetochemical characterization of 1, 3 and 4. Each member of this family of complexes displays a low symmetry structure that incorporates a {M4O4} core unit based on a distorted cubane. Magnetic measurements reveal ferromagnetic exchange interactions for 1, 3 and 4. These give rise to S = 4 ground state spins for the tetranuclear Ni complexes and an anisotropic effective S′ = 2 ground state for the Co complex. 相似文献
46.
Covalent assembly between gold-thiolate nanoparticles (AuNPs) and the cluster [Fe(eta(5)-C(5)H(5))(mu(3)-CO)](4), 1, can be achieved either by direct Brust-Schriffin-type synthesis using a mixture of undecanethiol and a thiol functionalized with , or by substitution of undecanethiolate ligands in AuNPs by thiolate ligands functionalized with ; cyclic voltammetry of these AuNPs functionalized with allows us to recognize and titrate the oxo-anions H(2)PO(4)(-) and ATP(2-). 相似文献
47.
Razavet M Artero V Cavazza C Oudart Y Lebrun C Fontecilla-Camps JC Fontecave M 《Chemical communications (Cambridge, England)》2007,(27):2805-2807
The reaction of the new and structurally characterized covalent {Mn(CO)(3)(H(2)O)(2)}(+)-lysozyme adduct with NiS(4) and NiN(2)S(2) complexes generates binuclear Ni-Mn complexes; relevance to the reactivity of the protein-bound {Fe(CO)(CN)(2)} intermediate during maturation of [NiFe] hydrogenases is discussed. 相似文献
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Colette M. Castleberry Kathleen Lilleness Rachel Baldauff Patrick A. Limbach 《Journal of mass spectrometry : JMS》2009,44(8):1195-1202
The use of isotopically labeled endonuclease digestion products allows for the relative quantification of ribonucleic acids (RNAs). This approach utilizes ribonucleases such as RNase T1 to mediate the incorporation of 18O onto the 3′‐terminus of the endonuclease digestion product from a solution containing heavy water (H218O). The accuracy and precision of relative quantification are dependent on the efficiency of isotope incorporation and minimizing any possible 18O to 16O back‐exchange before or during mass spectral analysis. Here, we have investigated the stability of 18O‐labeled endonuclease digestion products to back‐exchange. In particular, the effects of pH, temperature and presence of RNase on the back‐exchange process were examined using matrix‐assisted laser desorption/ionization mass spectrometry (MALDI‐MS). We have found that back‐exchange depends on the presence of the RNase—back‐exchange was not observed once the enzyme was removed from the sample. With RNase present, at all pH values examined (from acidic to basic pH), back‐exchange was detected at incubation above room temperature. The rates and extent of back‐exchange were similar at all pH values. In contrast, back‐exchange in the presence of RNase was found to be especially sensitive to incubation temperature—at temperatures below room temperature, minimal back‐exchange was detected. However, back‐exchange increased as the incubation temperature increased. Based on these findings, appropriate sample‐handling and sample storage conditions for isotopically labeled endonuclease digestion products have been identified, and these conditions should improve the accuracy and precision of results from the relative quantification of RNAs obtained by this approach. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献