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991.
D. Loss 《Journal of statistical physics》1990,59(3-4):691-723
The quantum-statistical generalization of the well-known classical, linear revised Enskog equation is derived for spatially uniform systems. This new quantum kinetic equation allows the study of equilibrium time correlation functions and their associated transport coefficients of normal quantum fluids where static correlations and degeneracy effects due to particle statistics (both are treated exactly) are important. Furthermore, we derive the quantum-statistical analog of the classical ring operator. These microscopic and systematic derivations are based on a recently developed superoperator formalism (including cluster expansion techniques) that, as a main feature, allows a clear distinction between static and dynamic correlations, which is crucial in the discussion of the Enskog approximation. 相似文献
992.
Douglas Poland 《Journal of statistical physics》1990,61(3-4):765-802
The coefficients in power series in the variable time that describe relaxation in a cooperative system can be calculated using a combinatorial approach where one considers how many ways one can introduce a given number of properly defined events in a system. The coefficients obtained in this manner can be related to the equilibrium virial coefficients for a mixture. If one assumes rapid internal equilibration, the relaxation process can be expressed completely in terms of the viral coefficients for a mixture with at most one solute particle, or, in some cases, just the virial coefficients for a single-component system. Thus, equilibrium virial coefficients can give useful information about the time evolution of processes in cooperative systems. 相似文献
993.
Teik-Cheng Lim 《Journal of mathematical chemistry》2002,32(3):249-256
Molecular mechanics softwares adopt various set of force field functions. In some cases, reliable data from one set of force field parameters cannot be used in a software that adopts another set of force field. Using mathematical approach, exact relationships between parameters from three bond-bending force fields, namely the (i) harmonic cosine angle, (ii) polynomial series, and (iii) Fourier series, are herein developed. Parameters from these three potential functions are further related to the approximate form, the harmonic angle function, which is valid for small change in chemical bond angle. 相似文献
994.
A novel method of computing the nonlinear differential equations relating to the transient behaviour of an induction motor using a polynomial series, is presented. The stator and rotor currents and the angle of rotation are expressed as polynomial series dependent on time. These are then substituted into the differential equations of the induction motor to compute the polynomial coefficients and, consequently, the transient quantities. Since the equations are nonlinear, the computations are carried out using the step-by-step method. The stator and rotor currents, speed and torque are calculated for acceleration and braking conditions. The results are compared both analytically and experimentally. 相似文献
995.
996.
V. V. Kalashnikov 《Queueing Systems》1990,6(1):113-136
Recently developed methods of qualitative analysis for regenerative processes arising in queueing are presented. These methods
are essentially qualitative and use notions such as coupling, probability metrics, etc. They are developed for studying various
properties of regenerative models, including convergence rate to a stationary regime, continuity of their characteristics
with respect to some parameters and first-occurrence time of an event such as queue overflowing. In spite of their qualitative
nature they lead to good quantitative estimates of underlying properties with computer methods available to calculate them. 相似文献
997.
A survey of retrial queues 总被引:18,自引:0,他引:18
Gennadij Falin 《Queueing Systems》1990,7(2):127-167
We present a survey of the main results and methods of the theory of retrial queues, concentrating on Markovian single and multi-channel systems. For the single channel case we consider the main model as well as models with batch arrivals, multiclasses, customer impatience, double connection, control devices, two-way communication and buffer. The stochastic processes arising from these models are considered in the stationary as well as the nonstationary regime. For multi-channel queues we survey numerical investigations of stationary distributions, limit theorems for high and low retrial intensities and heavy and light traffic behaviour. 相似文献
998.
Single line queue with repeated demands 总被引:2,自引:0,他引:2
K. Farahmand 《Queueing Systems》1990,6(1):223-228
We analyze a model of a queueing system in which customers can only call in to request service: if the server is free, the
customer enters service immediately, but if the service system is occupied, the unsatisfied customer must break contact and
reinitiate his request later. Such a customer is said to be in “orbit”. In this paper we consider three models characterized
by the discipline governing the order of re-request of service from orbit. First, all customers in orbit can reapply, but
are discouraged and reduce their rate of demand as more customers join the orbit. Secondly, the FCFS discipline operates for
the unsatisfied customers in orbit. Finally, the LCFS discipline governs the customers in orbit and the server takes an exponentially
distributed vacation after each service is completed. We calculate several characteristics quantities of such systems, assuming
a general service-time distribution and different exponential distributions for the times between arrivals of first and repeat
requests. 相似文献
999.
Helmut Willie 《Queueing Systems》1990,6(1):109-112
Explicit formulas for the individual call loss probabilities are derived which arise when a finite collection of independent
general stationary traffic streams with exponentially distributed service times are offered simultaneously to a single server.
The formulas show a modified insensitivity property of the given model. 相似文献
1000.
《Current Applied Physics》2014,14(8):1022-1027
The conventional electrolyte system has been compared with the ionic liquid (IL) additive containing electrolyte system at room temperature as well as elevated temperature. In this work, two types of monocationic ILs such as 1-butyl-3-methylpyrrolidinium hexafluorophosphate (Pyr IL) and 1-ethyl-3-methylimidazolium hexafluorophosphate (IMI IL) are added as an additive at two different weight ratios in 1.15 M LiPF6 (EC/EMC = 3/7 v/v) electrolyte solution, the structural, electrochemical and thermal characteristics of LiNi0.80Co0.15Al0.05O2 (NCA)/carbon full-cell in different electrolyte formulations have been reconnoitered. X-ray diffraction (XRD) studies have proved that IL as an electrolyte additive does not alter the structural stability of cathode materials after cycling. Under room temperature, Pyr IL additives at 1 wt% and 3 wt% deliver better cycleability than others, with the retention ratios of 93.62% and 92.8%, respectively. At elevated temperature, only 1 wt% Pyr IL additive is giving stable capacity retention ratio of 80.74%. Ionic conductivity and self-extinguishing time (SET) values are increasing with respect to the amount of additive added to the electrolyte. Thermal studies reveal that 3 wt% Pyr IL is favorable regarding the safety of the battery as it shows shifting of peak to higher temperature of 272.10 °C. Among the IL additives evaluated in this study, addition of 1 wt% Pyr IL is the most desirable additive for achieving the best cycling performance as well as thermal behavior of Li-ion batteries. 相似文献