Probabilistic arguments are given to explain some recent results on networks of queues. Those results are the product form, the output theorems, the distributions at the jumps, and the Poisson ...character of the flows. The proposed approach replaces the usual calculations by arguments showing these properties to be consequences of the behavior of the nodes in isolation.
Customers arrive in a Poisson stream into a network consisting of two M/M/1 service stations in tandem. The service rate u \in 0, a at station 1 is to be selected as a function of the state ( x_{1}, ...x_{2} ) where x i is the number of customers at station i so as to minimize the expected total discounted or average cost corresponding to the instantaneous cost c_{1}x_{1} + c_{2}x_{2} . The optimal policy is of the form u=a or u=0 according as x_{1} < S(x_{2}) or x_{1} \geq S(X_{2}) and S is a switching function. For the case of discounted cost, the optimal process can be nonergodic, but it is ergodic for the case of average cost.
We consider parameter estimation for a FIFO queue with deterministic service times and two independent arrival streams of "observed" and "unobserved" packets. The arrivals of unobserved packets are ...Poisson with an unknown rate /spl lambda/ while the arrivals of observed packets are arbitrary. Maximum likelihood estimation of /spl lambda/ is formulated based on the arrival times and waiting times of k observed packets. The likelihood function is derived in terms of the transition probabilities of the unfinished work process which are calculated recursively. Sufficient conditions for consistency, asymptotic normality, and asymptotic efficiency are given. The mean and variance of the MLE are measured in simulation experiments. Numerical results indicate that the MLE is consistent and asymptotically normal.< >
Using diode-laser spectroscopy, the intensities of 58 lines of the
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1+
ν
2
1−
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2
1 band and 36 lines of the 2
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1 band of OCS have been measured. The corresponding band strengths
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0 and the ...vibrational transition dipoles
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have been derived through least squares fitting of these individual intensities. The band strengths values have been determined with a precision better than 2.5%.
Dynamic priority protocols for packet voice Chen, T.M.; Walrand, J.; Messerschmitt, D.G.
IEEE journal on selected areas in communications,
06/1989, Letnik:
7, Številka:
5
Journal Article
Recenzirano
Odprti dostop
Since the reconstruction of continuous speech from voice packets is complicated by the variable delays of the packets through the network, a dynamic priority protocol is proposed to minimize the ...variability of packet delays. The protocol allows the priority of a packet to vary with time. After a discussion of the concept of dynamic priorities, two examples of dynamic priorities are studied through queueing analysis and simulations. Optimal properties of the oldest customer first (OCF) and earliest deadline first (EDF) disciplines are proven, suggesting that they may be theoretically effective in reducing the variability of packet delays. Simulation results of the OCF discipline indicate that the OCF discipline is most effective under conditions of long routes and heavy traffic, i.e., the conditions when delay variability is most likely to be significant. Under OCF, the delays of packets along long routes are improved at the expense of packets along short routes. It is noted that more complex and realistic simulations, including simulations of the EDF discipline, are needed.< >
This paper analyzes open networks of quasireversible nodes with a single class of customers and in equilibrium. A simple argument shows, under a stability conditions, that a flow on a link of such a ...network is Poisson if and only if the link is not part of a loop. This loop criterion is shown to apply to the usual quasireversible networks with bounded service rates.
Consider a network of queues in equilibrium. When are the flows observed on two given links of that network equivalent, i.e., when do they have the same law? The verification of the equivalence of ...two such point processes is first reduced to an algebraic problem by a technique based on the filtering theory. This method is then used to show that the arrival and departure processes at an M/M/1 node in a Jackson network are not always equivalent, thereby contradicting a conjecture made in 8. An example where that equivalence holds is also given; it provides new results on the time reversibility of some familiar processes.
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