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951.
Khosrow Sohraby 《Annals of Operations Research》1994,49(1):325-346
We consider multiplexers in discrete time fed by the superposition of Ternary Markov Sources. Such sources are the natural extension of the Binary Markov Sources (BMS) recently used to model bursty arrivals in a high speed environment. Unlike BMS, we allow sources to have arbitrary (large) variance in the duration of their OFF (silence) or ON (burst) periods.This paper focuses mainly on the impact of large variability either in the ON or OFF period on the performance. Following some asymptotic analysis, simple results on the tail behavior of the number of cells queued in the multiplexer are given.Our results indicate that ignoring the variability in the ON period may grossly underestimate the cell buildup in the multiplexer queue for all levels of the utilization. Furthermore, the impact of large variability of the OFF period depends very much on the utilization of the system. For a lightly-loaded multiplexer (utilization below a given threshold), the impact of large variability of the OFF period is minimal. However, for a heavy-loaded multiplexer (utilization above the threshold) the impact of the large variability in the OFF period is similar to that of the ON period. 相似文献
952.
J. D. Pandey Siddharth Pandey Shikha Gupta A. K. Shukla 《Journal of solution chemistry》1994,23(9):1049-1059
Viscosities of ternary liquid mixtures containing benzene + cyclohexane + carbon tetrachloride and the three possible binary combinations were measured at 25°C, and the excess viscosities were computed. Theoretical expressions for viscosity were developed on the basis of the Flory theory, the significant structure theory and a theory based on a method of estimating the properties of multi-component systems from those of binary systems. Reasonable agreement between experimental and theoretical viscosities is found. 相似文献
953.
The Langmuirian Adsorption Kinetics Revised: A Farewell to the XXth Century Theories? 总被引:2,自引:0,他引:2
A brief historical review of the development of the theoretical approaches to the kinetics of gas adsorption/desorption on/from the solid surfaces is presented. The attention is focused on new approaches, challenging the classical theories based on the ideas of Absolute Rate Theory (ART). These new approaches relate the adsorption/desorption kinetics to the chemical potentials of the molecules in the gas and adsorbed states. Among them the so-called Statistical Rate Theory (SRT) has the most rigorous theoretical foundations. That new approach predicts that depending on experimental conditions one can have a variety of kinetic equations corresponding to the Langmuir equilibrium adsorption isotherm. 相似文献
954.
Phase behavior and structural properties of homogeneous and inhomogeneous core-softened (CS) fluid consisting of particles interacting via the potential, which combines the hard-core repulsion and double attractive well interaction, are investigated. The vapour-liquid coexistence curves and critical points for various interaction ranges of the potential are determined by discrete molecular dynamics simulations to provide guidance for the choice of the bulk density and potential parameters for the study of homogeneous and inhomogeneous structures. Spatial correlations in the homogeneous CS system are studied by the Ornstein-Zernike integral equation in combination with the modified hypernetted chain (MHNC) approximation. The local structure of CS fluid subjected to diverse external fields maintaining the equilibrium with the bulk CS fluid are studied on the basis of a recently proposed third order+second order perturbation density functional approximation (DFA). The accuracy of DFA predictions is tested against the results of a grand canonical ensemble Monte Carlo simulation. Reasonable agreement between the results of both methods proves that the DFA theory applied in this work is a convenient theoretical tool for the investigation of the CS fluid, which is practically applicable for modeling numerous real systems. 相似文献
955.
Local exchange-correlation potential has been derived starting from the free electron gas model.Ab initio way of calculating the parameter of the X method is presented. Self-consistent and statistical exchange-correlation parameters have been determined. The self-consistent parameters have been used to calculate the electron binding energies of Neon, Argon and Krypton. We suggest using statistical exchange-correlation parameter in molecular calculations. The statistical exchange-correlation parameter has been applied to study the electron binding energies of the molecules H2O and HF. It is shown that the electron binding energies calculated with the self-consistent and the statistical parameters show agreement with the experimental values.Dedicated to Professor J. Koutecký on the occasion of his 65th birthday 相似文献
956.
利用统计缔合流体理论状态方程预测混合气体水合物的平衡形成条件 总被引:2,自引:0,他引:2
利用统计缔合流体理论(SAFT)状态方程结合van der Waals-Platteeuw统计力学模型用于预测含有甲烷、乙烷、丙烷、乙烯、丙烯、H2S, CO2, N2和H2二元气体水合物的平衡形成条件. 对于气相和液相, 应用SAFT方程来描述. 在气相和液相相平衡的模拟过程中, SAFT方程考虑了硬球斥力、成链力、色散力以及缔合相互作用. 对于水合物相, 采用van der Waals-Platteuw模型来计算. 该方法的预测结果与实验数据吻合. 相似文献
957.
Andrea Salvo Archimede Rotondo Nicola Cicero Romana Gargano Valentina Mangano 《Natural product research》2019,33(19):2815-2822
Origanum vulgare L. samples, marketed in different geographic locations, were characterized by their organic and inorganic chemical composition. A total of 35 commercial samples were collected from various sites and analyzed to determine the qualitative and quantitative profile of essential oils, phenolic compounds and some inorganic elements. The variation in the content and composition of the essential oil was assessed by GC and GC-MS analyses, the phenolic fraction was investigated by UPLC®/PDA, and the inorganic elements were determined by ICP-MS. The Principal Component Analysis (PCA) was applied with the aim to sort out the Origanum vulgare L. samples with different composition according to the different belonging origins. The results showed appreciable qualitative and quantitative differences among samples from different geographic origin. 相似文献
958.
Anamaria Iulia Torok Erika Andrea Levei Silviu Constantin Oana Teodora Moldovan Marin Senila Oana Cadar Dorina Casoni Simion Bogdan Angyus Claudiu Tanaselia Eniko Covaci Tiberiu Frentiu 《Molecules (Basel, Switzerland)》2021,26(22)
The aim of the study was to develop the hydrogeochemical profiling of caves based on the elemental composition of water and silty soil samples and a multivariate statistical analysis. Major and trace elements, including rare earths, were determined in the water and soil samples. The general characteristics of water, anions content, inorganic and organic carbon fractions and nitrogen species (NO3− and NH4+) were also considered. The ANOVA—principal component analysis (PCA) and two-way joining analysis were applied on samples collected from Cloșani Cave, Romania. The ANOVA-PCA revealed that the hydrogeochemical characteristics of Ca2+-HCO3− water facies were described by five factors, the strongest being associated with water-carbonate rock interactions and the occurrence of Ca, Mg and HCO3− (43.4%). Although organic carbon fractions have a lower influence (20.1%) than inorganic ones on water characteristics, they are involved in the chemical processes of nitrogen and of the elements involved in redox processes (Fe, Mn, Cr and Sn). The seasonal variability of water characteristics, especially during the spring, was observed. The variability of silty soil samples was described by four principal components, the strongest influence being attributed to rare earth elements (52.2%). The ANOVA-PCA provided deeper information compared to Gibbs and Piper diagrams and the correlation analysis. 相似文献
959.
S. I. Kuchanov A. G. Kholostyakov 《Journal of polymer science. Part A, Polymer chemistry》1999,37(13):2145-2154
Potentialities have been examined of the application of the statistical method for the approximate calculation of the gel point in the case of nonideal branched homopolycondensation, depending on the parameters of its kinetic model. Along with a traditional first-order approximation, the more sophisticated second-order approximation has been scrutinized. Conditions have been revealed when traditional approximation would suffice for the calculation of the gel point. The regions are specified within the parameter space where the recourse to the second-order approximation has been found to substantially increase the accuracy of the calculation of this point as well as those regions in which the employment of the statistical method is unlikely to be advisable. This influence has also been considered for both the simplification of the “First Shell Substitution Effect” model and the monomer functionality evolution on the accuracy of the gel point calculation by the statistical method. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 2145–2154, 1999 相似文献
960.
Luigi C. Berselli 《Mathematical Methods in the Applied Sciences》1999,22(13):1079-1085
In this paper we find sufficient conditions, involving only the pressure, that ensure the regularity of weak solutions to the Navier–Stokes equations. Conditions involving only the pressure were previously obtained in [7,4]. Following a remark in this last reference we improve, in particular, Kaniel's result [7]. Our condition can be seen at the light of the heuristic idea that the pressure behaves similarly to the modulus squared of the velocity. Copyright © 1999 John Wiley & Sons, Ltd. 相似文献