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We investigate a variety of known and new approaches for the estimation of the parameters of discrete-time semi-Markovian
traffic models. We focus on modeling video traffic, since the accurate representation of its long-term autocorrelation is
a challenge to the parameter estimation methods. The modeling techniques are applied to sample H.264/AVC-encoded video traces.
We study their ability to reflect the autocorrelation and variability of the original traffic and also the delay probabilities
of a resulting SMP/GI/1 queueing system. The delay probabilities are determined both by simulation and verified analysis of
the queue. 相似文献
115.
This paper provides an overview of European activities in the field of optical local-area networks (LAN's). The fully developed systems are currently at the process control and automation stage. Comparative estimates of the cost effectiveness of optical and electrical LAN's in industrial applications favor the optical systems. To date, deterministic protocols have predominately been used. Statistical access protocols are favored by Ethernet and are gaining in importance. Recent developments aim at mixed protocols which allow simultaneous transmission of both speech and data. The most important characteristics and results obtained with different optical LAN's are compared in a table. 相似文献
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Wolfram W. Rudolph 《Journal of solution chemistry》2010,39(7):1039-1059
Measurements have been made of the Raman spectra of aqueous solutions of Be(ClO4)2, BeCl2, (NH4)2SO4 and BeSO4 to 50 cm−1. In some cases low concentrations (0.000770 mol⋅kg−1) have been used and two temperatures (23 and 40 °C) were studied. In BeSO4(aq), the ν
1-SO42-\mathrm{SO}_{4}^{2-} mode at 980 cm−1 broadens with increasing concentration and shifts to higher wavenumbers. At the same time, a band at 1014 cm−1 is detectable with this mode being assigned to [BeOSO3], an inner-sphere complex (ISC). Confirmation of this assignment is provided by the simultaneous appearance of stretching
bands for the Be2+-OSO32-\mathrm{Be}^{2+}\mbox{-}\mathrm{OSO}_{3}^{2-} bond of the complex at 240 cm−1 and for the BeO4 skeleton mode of the [(H2O)3BeOSO3] unit at 498 cm−1. The ISC concentration increases with higher temperatures. The similarity of the n1-SO42-\nu_{1}\mbox{-}\mathrm{SO}_{4}^{2-} Raman bands for BeSO4 in H2O and D2O is further strong evidence for formation of an ISC. After subtraction of the ISC component at 1014 cm−1, the n1-SO42-\nu_{1}\mbox{-}\mathrm{SO}_{4}^{2-} band in BeSO4(aq) showed systematic differences from that in (NH4)2SO4(aq). This is consistent with a n1-SO42-\nu_{1}\mbox{-}\mathrm{SO}_{4}^{2-} mode at 982.7 cm−1 that can be assigned to the occurrence of an outer-sphere complex ion (OSCs). These observations are shown to be in agreement
with results derived from previous relaxation measurements. Infrared spectroscopic data show features that are also consistent
with a beryllium sulfato complex such as the appearance of a broad and weak n1-SO42-\nu_{1}\mbox{-}\mathrm{SO}_{4}^{2-} mode at ∼1014 cm−1, normally infrared forbidden, and a broad and asymmetric n3-SO42-\nu_{3}\mbox{-}\mathrm{SO}_{4}^{2-} band contour which could be fitted with four band components (including n3-SO42-(aq)\nu_{3}\mbox{-}\mathrm{SO}_{4}^{2-}(\mathrm{aq})). The formation of ISCs in BeSO4(aq) is much more pronounced than in the similar MgSO4(aq) system studied recently. 相似文献
118.
George Kornaros Matthias Sund Wolfram Lautenschlaeger Helen-Catherine Leligou Theofanis Orphanoudakis 《AEUE-International Journal of Electronics and Communications》2010,64(1):17-28
Aggregating Ethernet frame or IP packet in large fixed-size frames allows for building scalable core network architectures. Classifying the arriving traffic based on destination core node information and quality of service parameters alleviates the need of performing table look-ups on packet basis. These advantages come at the cost of extra logic at the network egress, as regards implementation, and additional jitter due to the frame assembly process. This paper describes the efficient implementation of a frame aggregation unit that gathers Ethernet packets in G.709 containers, handles 10 Gb/s links, performs classification based on 24-byte headers, and includes a highly pipelined Queue Manager to cope with the considered rates while a specific scheduler controls the quality of service per core network flow. Based on the developed demonstrator, we provide results both as regards area and performance for an FPGA (field programmable gate array) Virtex-4 implementation as well as regarding the introduced jitter. 相似文献
119.
Rosemarie Philipp Olaf Hanebeck Sebastian Hein Wolfram Bremser Tin Win Irene Nehls 《Accreditation and quality assurance》2010,15(3):141-146
The Federal Institute for Materials Research and Testing (BAM), Germany, has issued a series of large volume ethanol in water
certified reference materials (CRMs), primarily developed for the calibration of evidential breath alcohol analyzers in Germany.
The certified parameter is the ethanol mass concentration at 20 °C. When used in a wet bath simulator, the solutions deliver
gas samples that meet the requirements set by the Organization of Legal Metrology for calibration of breathalyzers. The materials
were prepared gravimetrically by spiking of ethanol into water in single 5 L units. A complete uncertainty budget for the
preparation process has been established. The purity of the commercial ethanol stock solution was identified to be the main
source of uncertainty. For stability and homogeneity measurements and for the verification of the gravimetric mass concentration
of the CRMs, a robust high-precision gas chromatography, with flame-ionization detection method for ethanol determination
in aqueous samples was developed and validated. The good performance of this method has been demonstrated in several international
comparisons organized by the Consultative Committee for Amount of Substance—Metrology in Chemistry at the International Bureau
of Weights and Measures. 相似文献
120.