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Maury Bramson 《Journal of statistical physics》1988,51(5-6):863-869
Recent results on two interacting particle systems on are summarized, the asymmetric simple exclusion process and the branching exclusion process. 相似文献
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E. J. Wyse J. A. MacLellan C. W. Lindenmeier J. P. Bramson D. W. Koppenaal 《Journal of Radioanalytical and Nuclear Chemistry》1998,234(1-2):165-170
The ever-increasing sensitivity of ICPMS continues to expand the technique’s application in the field of health physics. Enhancements
in sample introduction and instrument design over the last few years have resulted in improving the ICPMS detection limit
from ∼10 ng/l to≤0.1 ng/l. This additional sensitivity provides greater flexibility in the analysis of long-lived radionuclides
in biological fluids, and requires only minimal sample preparation of urine for uranium analysis; the described 3-minute abbreviated
matrix separation provides detection limits that are comparable to or better than alpha counting. For urine samples tested
having concentrations that exceed the accepted administrative limit for total uranium (0.2 μg/day), isotopic analysis by ICPMS
(e.g., determining the presence of236U, or measuring appropriate uranium isotope ratios) provides a reliable indication of occupational exposure. Our laboratory
also utilizes ICPMS in a study examining uranium dissolution rate classification of dust collected at the perimeter of a nuclear
facility. Specific details regarding these and other health physics applications are featured, including our group’s participation
in assisting the DOE with the evaluation of ICPMS as a cost-effective alternative to fission-track analysis for the routine
determination of239Pu in urine. 相似文献
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We study multiclass queueing networks with the earliest-due-date, first-served (EDDFS) discipline. For these networks, the service priority of a customer is determined, upon its arrival in the network, by an assigned random due date. First-in-system, first-out queueing networks, where a customer's priority is given by its arrival time in the network, are a special case. Using fluid models, we show that EDDFS queueing networks, without preemption, are stable whenever the traffic intensity satisfies
j
<1 for each station j. 相似文献
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State space collapse with application to heavy traffic limits for multiclass queueing networks 总被引:3,自引:0,他引:3
Heavy traffic limits for multiclass queueing networks are a topic of continuing interest. Presently, the class of networks
for which these limits have been rigorously derived is restricted. An important ingredient in such work is the demonstration
of state space collapse. Here, we demonstrate state space collapse for two families of networks, first-in first-out (FIFO)
queueing networks of Kelly type and head-of-the-line proportional processor sharing (HLPPS) queueing networks. We then apply
our techniques to more general networks. To demonstrate state space collapse for FIFO networks of Kelly type and HLPPS networks,
we employ law of large number estimates to show a form of compactness for appropriately scaled solutions. The limits of these
solutions are next shown to satisfy fluid model equations corresponding to the above queueing networks. Results from Bramson
[4,5] on the asymptotic behavior of these limits then imply state space collapse. The desired heavy traffic limits for FIFO
networks of Kelly type and HLPPS networks follow from this and the general criteria set forth in the companion paper Williams
[41]. State space collapse and the ensuing heavy traffic limits also hold for more general queueing networks, provided the
solutions of their fluid model equations converge. Partial results are given for such networks, which include the static priority
disciplines.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
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Summary Gray and Griffeath studied attractive nearest neighbor spin systems on the integers having “all 0's” and “all 1's” as traps.
Using the contour method, they established a necessary and sufficient condition for the stability of the “all 1's” equilibrium
under small perturbations. In this paper we use a renormalized site construction to give a much simpler proof. Our new approach
can be used in many situations as a substitute for the contour method.
Partially supported by a grant from the National Science Foundation
Partially supported by the Army Research Office through the Mathematical Sciences Institute at Cornell University 相似文献
8.
Maury Bramson J. Theodore Cox David Griffeath 《Probability Theory and Related Fields》1988,77(3):401-413
This paper is a sequel to [5] and [6]. We continue our study of occupation time large deviation probabilities for some simple infinite particle systems by analysing the so-called voter model t (see e.g., [11] or [8]). In keeping with our previous results, we show that the large deviations are classical in high dimensions (d5 for t) but fat in low dimensions (d4). Interaction distinguishes the voter model from the independent particle systems of [5] and [6], and consequently exact computations no longer seem feasible. Instead, we derive upper and lower bounds which capture the asymptotic decay rate of the large deviation tails.Dedicated to Frank Spitzer on his 60th birthdayPartially supported by the National Science Foundation under Grant DMS-831080Partially supported by the National Science Foundation under Grant DMS-841317Partially supported by the National Science Foundation under Grant DMS-830549 相似文献
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Summary Branching annihilating random walk is an interacting particle system on . As time evolves, particles execute random walks and branch, and disappear when they meet other particles. It is shown here that starting from a finite number of particles, the system will survive with positive probability if the random walk rate is low enough relative to the branching rate, but will die out with probability one if the random walk rate is high. Since the branching annihilating random walk is non-attractive, standard techniques usually employed for interacting particle systems are not applicable. Instead, a modification of a contour argument by Gray and Griffeath is used. 相似文献
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Maury D. Bramson 《Probability Theory and Related Fields》1978,45(2):89-108
Summary Let
denote a branching random walk in
with mean particle productionm, m>1, and with incremental spatial distributionG, withG({0}) =p andG({1})=1–p. Ifmp=1, then the minimal displacement of
behaves asymptotically like log logn/log 2. If the conditionG({1})=1–p is replaced byG((0, ))=1–p, we obtain a similar result.Research was partially supported by the National Science Foundation under grant MCS-7607039 相似文献