Analytic and Numerical Solutions of an <Emphasis Type="Italic">N</Emphasis> Duplicate-Server System

We consider an N duplicate-server system, where each server consists of two reconfigurable duplicated units which are subject to breakdowns. This system is studied analytically using generating-functions, and also numerically using the matrix-geometric procedure. Using the generating-function approach we obtain a recursive expression of the queue-length probability distribution for N = 1. This expression is difficult to generalize to N ? 2. The numerical method is applicable for any value of N. For any N, we also obtain the condition for stability and the availability of the system.     

Bandwidth allocation under end‐to‐end percentile delay bounds

We describe an efficient and accurate approximation method for calculating the bandwidth that should be allocated on each link along the path of a point‐to‐point Multiprotocol Label Switching connection, so that the end‐to‐end delay D is less than or equal to a given value T with a probability γ, that is, P(D ≤ T) = γ. We model a connection by a tandem queuing network of infinite capacity queues. The arrival process of packets to the connection is assumed to be bursty and correlated and it is depicted by a two‐stage Markov‐Modulated Poisson Process. The service times are exponentially distributed. The proposed method uses only the first queue of the tandem queuing network to construct an upper and lower bound of the required bandwidth so that P(D ≤ T) = γ. Subsequently, we estimate the required bandwidth using a simple interpolation function between the two bounds. Extensive comparisons with simulation showed that the results obtained have an average relative error of 1.25%. Copyright © 2011 John Wiley & Sons, Ltd.     

Quality of Service in an Optical Burst Switching Ring

Several access protocols are proposed to support different service classes in an optical burst switched ring. Their performance is evaluated through simulation. Various performance metrics such as throughput, utilization, burst loss rate, end-to-end delay and fairness are used to analyze the behavior of each protocol.This work was supported by ARDA under contracts MDA904-00-C-2133 and MDA904-02-C-0482.     

A two‐level queueing network model with blocking and non‐blocking messages

We analyze a novel twolevel queueing network with blocking, consisting of N level1 parallel queues linked to M level2 parallel queues. The processing of a customer by a level1 server requires additional services that are exclusively offered by level2 servers. These level2 servers are accessed through blocking and nonblocking messages issued by level1 servers. If a blocking message is issued, the level1 server gets blocked until the message is fully processed at the level2 server. The queueing network is analyzed approximately using a decomposition method, which can be viewed as a generalization of the wellknown twonode decomposition algorithm used to analyze tandem queueing networks with blocking. Numerical tests show that the algorithm has a good accuracy.     

Mass spectrometric study of conjugated bifunctional acetylenes. 1—Enynes

This study on the fragmentation of conjugated enynes demonstrates the relationships between the mass spectra and the structures of these compounds. The rearrangements of the molecular ions and the fragment ions are characterized; the mechanisms by which the most important peaks are formed have been established and detailed analysis of the metastable transitions reveals all the fragmentation steps. A complete scheme is presented for 2-methyl-1-nonene-3-yne since it includes all the transitions which can be detected for the lower homologues. The ion kinetic energy spectra for this family of compounds are distinct (even though the conventional spectra are similar) and could very well be used for identification purposes.     

JumpStart: a just-in-time signaling architecture for WDMburst-switched networks

We present an architecture for a core dWDM network which utilizes the concept of optical burst switching coupled with a just-in-time signaling scheme. It is a reservation-based architecture whose distinguishing characteristics are its relative simplicity, its amenability to hardware implementation, and the ability to support multicast natively. Another important feature is data transparency-the network infrastructure is independent of the format of the data being transmitted on individual wavelengths. We present the signaling protocol designed for this architecture, as well as an unified signaling message structure to be used in conjunction with the protocol. We also present the future directions of this research     

A bibliography of ATM related papers

In this paper, we give a list of ATM related papers. This is not a complete list. Rather, it represents the bulk of the references in this ever-growing area. For easier use of this reference list, we have classified the papers into the following six categories: general, source characterization, switching, congestion control, routing, and transport.     

Computing call-blocking probabilities in LEO satellite networks:the single-orbit case

We study the problem of carrying voice calls over a low-Earth-orbit satellite network and present an analytical model for computing call-blocking probabilities for a single orbit of a satellite constellation. We have devised a method to solve the corresponding Markov process efficiently for orbits of up to five satellites. For orbits consisting of a larger number of satellites, we have developed an approximate decomposition algorithm to compute the call-blocking probabilities by decomposing the system into smaller subsystems and iteratively solving each subsystem in isolation using the exact Markov process. Our approach can capture blocking due to handoffs for both satellite-fixed and Earth-fixed constellations. Numerical results demonstrate that our method is accurate for a wide range of traffic patterns and for orbits with a number of satellites that is representative of commercial satellite systems