Showing papers on "Network topology published in 1970"

Realization of modified cut-set matrix and applications

Abstract: The concepts of network of departure and padding n-port network are defined and certain important properties of these networks are stated. A necessary and sufficient criterion for the realization of the modified cut-set matrix of a resistive n-port network having a prescribed configuration is given. A new approach to the synthesis of short-circuit conductance matrix of a resistive n-port network with more than (n + 1) nodes is outlined. Necessary and sufficient conditions for the realization of the potential factor matrix of an (n + 2) node resistive n-port network are also obtained. These conditions lead to a simple t&t for the realizability of the modified cut-set matrix of an (n + 2) node n-port network. Examples are worked out to illustrate the application of these results.

State-equation formulation for multiport networks

Abstract: Explicit formulas are obtained for the state equations of a network in terms of those of its (linear or nonlinear) multiport components and the network graph. Increased generality and simplicity is obtained through the use of the scattering formalism. This allows the inclusion of most nonpathological components without the impedance-admittance hybridization that greatly complicates the common RLC formulations. In both the linear and nonlinear cases a simple test for the existence of state equations is obtained in terms of the properties of a linear memoryless "subnetwork."

Power-Aware Logical Topology Optimization for IP-over-WDM Networks Based on Per-Lightpath Power Consumption Model

Abstract: This paper considers the problem of logical topology optimization in an IP-over-WDM network, with the objective to minimize the total power consumption used to support the given traffic demands. While there are several power consuming devices in a backbone WDM network, it is assumed that major power consumption occurs at IP router ports, which are termination points of optical connections or lightpaths. The logical topology optimization problem is first formulated as an integer linear programming (ILP) problem that is computationally difficult to solve. To focus on minimizing the power consumption, it is assumed that traffic routing is not limited by link capacities. Two systematic approaches to obtain a lower bound on the power consumption are considered, namely linear programming (LP) relaxation and Lagrangian relaxation. It is shown that both methods result in the same lower bound that corresponds to shortest path routing of traffic. A heuristic based on shortest path routing and pruning of unnecessary lightpaths is then evaluated using simulation results obtained from the heuristic in comparison to the baseline case in which the logical topology is taken to be the same as the physical topology. Finally, WDM networks that support mixed line rates are considered in order to further optimize the power consumption of IP-over-WDM networks in which transmission rates over different wavelength channels are not necessarily equal.

Routing Optimization By Concurrent GeneticAlgorithms

Abstract: A parallel implementation of genetic algorithms is applied to routing protocols with low bandwidth consumption. In particular, the paper discusses the (LSP) link state packet protocols. The first part of the paper deals with network topology and transmission parameters, together with the structure for storing the network. The second part discusses the Genetic Algorithm implementation. To this end, it considers the generation of the initial population that is a subset of all the possible paths connecting couples of nodes. As far as the mating and mutation policy is concerned, a strategy is proposed that allows the algorithm to replace segments of the entire path The implementation is carried out in parallel, thus letting different populations to evolve separately. Subsets of different populations migrate periodically to avoid the populations to persist in some local minima. These are the equilibrium states, where no better path, with a lower cost, can be found for a given period. As for conclusions, comparisons between the results of the sequential and distributed implementations of Genetic Algorithms are reported.

Leak Detection And Monitoring In Hydraulic Networks

Abstract: Managing water distribution systems includes detection of leaks to improve the effectiveness of the service. The section of a hydraulic network where a leak occurs can be detected if the SCADA SYSTEM is coupled to a software based on the Method of Characteristics (MOC), which is, presently, the best one to simulate steady and unsteady flows, as shown by illustrative examples in this paper. The paper shows the basic equations and describes the basis of the computer program and corresponding network topology description that provide the engineer with the easiest way to simulate network operation. The use of MOC, for both steady and unsteady flow monitoring, facilitates the network calibration in order to reduce the sensitivity of the data errors due to inaccuracy in the value of friction factors.

Artificial Intelligence For Secure NetworkCommunications

Abstract: The national telecommunications infrastructure is increasing rapidly in complexity and the numbers of interconnected networks. To ensure high quality telecommunications service, Dr. Johnson and her students are developing an expert system that monitors evolution of the network and rejects proposals for evolution that violate rules that are built into the system. They are using an object-oriented graphical language for the rules and for constructing the user interface. Initially, they are concerned with changing network topologies and the software developed is called an expert system for network configuration. This is one part of their research goal of providing a network planning system that plans network topologies based on demands for service. Their focus is on interconnected voice networks as opposed to the rapidly emerging data services (e.g., email). The methods are expected to apply also to data networks. Three students are involved all of whom are now employed full time at telecommunications companies in Canada and continue their work on the project by providing consultation and writing scholarly papers coauthored by Dr. Johnson. We report investigative and preliminary work undertaken by Johnson and her students at the University of Regina in the area of network communications security, modelling and management. Transactions on Information and Communications Technologies vol 16, © 1996 WIT Press, www.witpress.com, ISSN 1743-3517