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71.
72.
Moshe Gitterman 《Journal of statistical physics》1994,74(5-6):1327-1328
73.
Moshe Marcus 《Calculus of Variations and Partial Differential Equations》1998,6(2):123-142
We consider the problem of minimizing functionals of the form , for small , subject to the constraint . (Here is typically a double well potential.) We study structural properties of minimizers that are shared by all minimizers of
the problem, for sufficiently small values of . It is shown that the average ‘mass’ and ‘energy’ of minimizers, over intervals of length , is almost uniformly distributed (depending on ), for all sufficiently small . Here is a constant depending on the degree of ‘uniformity’, but independent of .
Received May 5, 1996 / Accepted October 28, 1996 相似文献
74.
It is shown that if R is a finitely generated integral domain of zero characteristic, then for every n there exist elements of R which are not sums of at most n units. This applies in particular to rings of integers in finite extensions of the rationals. On the other hand there are
many infinite algebraic extensions of the rationals in which every integer is a sum of two units. 相似文献
75.
We study the message queueing delays in a node of a communication system, where a message consists of a block of consecutive packets. The message delay is defined as the time elapsing between the arrival epoch of the first packet of the message to the system until after the transmission of the last packet of that message is completed. We distinguish between two types of message generation processes. The message can be generated as abatch or it can bedispersed over time. In this paper we focus on the dispersed generation model. The main difficulty in the analysis is due to the correlation between the system states observed by different packets of the same message. This paper introduces a new technique to analyze the message delay in such systems for different arrival models and different number of sessions. For anM/M/1 system with variable size messages and for the bursty traffic model, we obtain an explicit expression for the Laplace-Stieltjes transform (LST) of the message delay. Derivations are also provided for anM/G/1 system, for multiple session systems and for fixed message sizes. We show that the correlation has a strong effect on the performance of the system, and that the commonly usedindependence assumption, i.e., the assumption that the delays of packets are independent from packet to packet, can lead to wrong conclusions. 相似文献
76.
Michael Shapiro Vladislav Dudko Victor Royzen Yuri Krichevets Samuel Lekhtmakher Victor Grozubinsky Moshe Shapira Moti Brill 《Particle & Particle Systems Characterization》2004,21(4):268-275
The thermal conductivity of ceramic powder packed beds was measured at temperatures below 100 °C for various powder sizes and compositions and under different gas atmospheres. Measurements at low pressures (down to 10 Pa) combined with a theoretical model allowed the elucidation of geometrical and thermal resistance parameters for the contact points between granules. The gap thickness and contact point size were found to be well correlated with the mean particle size. The thermal conductivities of all powders at low pressure were found to differ at most by a factor of two, whereas the solid‐phase conductivities of the powder materials differed by more than one order of magnitude. A theoretical model accounting for the size‐dependence of contact point conductivity is incorporated to rationalize this trend. 相似文献
77.
A continuous–discontinuous second‐order transition in the satisfiability of random Horn‐SAT formulas
Cristopher Moore Gabriel Istrate Demetrios Demopoulos Moshe Y. Vardi 《Random Structures and Algorithms》2007,31(2):173-185
We compute the probability of satisfiability of a class of random Horn‐SAT formulae, motivated by a connection with the nonemptiness problem of finite tree automata. In particular, when the maximum clause length is three, this model displays a curve in its parameter space, along which the probability of satisfiability is discontinuous, ending in a second‐order phase transition where it is continuous but its derivative diverges. This is the first case in which a phase transition of this type has been rigorously established for a random constraint satisfaction problem. © 2007 Wiley Periodicals, Inc. Random Struct. Alg., 2007 相似文献
78.
We consider the problem of determining lot sizes of multiple items that are manufactured by a single capacitated facility. The manufacturing facility may represent a bottleneck processing activity on the shop floor or a storeroom that provides components to the shop floor. Items flow from the facility to a downstream facility, where they are assembled according to a specified mix. Just-in-time (JIT) manufacturing requires a balanced flow of items, in the proper mix, between successive facilities. Our model determines lot sizes of the various items based on available capacity and four attributes of each item: demand rate, holding cost, set-up time and processing time. Holding costs for each item accrue until the appropriate mix of items is available for shipment downstream. We develop a lot-sizing heuristic that minimizes total holding cost per time unit over all items, subject to capacity availability and the required mix of items. 相似文献
79.
The intuition while observing the economy of queueing systems, is that one’s motivation to join the system, decreases with
its level of congestion. Here we present a queueing model where sometimes the opposite is the case. The point of departure
is the standard first-come first-served single server queue with Poisson arrivals. Customers commence service immediately
if upon their arrival the server is idle. Otherwise, they are informed if the queue is empty or not. Then, they have to decide
whether to join or not. We assume that the customers are homogeneous and when they consider whether to join or not, they assess
their queueing costs against their reward due to service completion. As the whereabouts of customers interact, we look for
the (possibly mixed) join/do not join Nash equilibrium strategy, a strategy that if adopted by all, then under the resulting
steady-state conditions, no one has any incentive not to follow it oneself. We show that when the queue is empty then depending
on the service distribution, both ‘avoid the crowd’ (ATC) and ‘follow the crowd’ (FTC) scenarios (as well as none-of-the-above)
are possible. When the queue is not empty, the situation is always that of ATC. Also, we show that under Nash equilibrium
it is possible (depending on the service distribution) that the joining probability when the queue is empty is smaller than
it is when the queue is not empty.
This research was supported by The Israel Science Foundation Grant No. 237/02. 相似文献
80.
Moshe Jarden 《Mathematische Zeitschrift》1997,224(4):555-565