Showing papers on "Network planning and design published in 1980"

Worst-Case Analysis of Network Design Problem Heuristics

Abstract: The Optimal Network problem (as defined by A. J. Scott, The optimal network problem : Some computational procedures, Trans. Res., Vol 3 (1969) pp. 201–210) consists of selecting a subset of arcs that minimizes the sum of the shortest paths between all nodes subject to a budget constraint. This paper considers the worst-case behavior of heuristics for this problem. Let n be the number of nodes in the network and $\varepsilon $ be a constant between 0 and 1. For a general class of Optimal Network Problems, we show that the question of finding a solution which is always less than $n^{1 - \varepsilon } $ times the optimal solution is $NP$-complete. This indicates that all polynomial-time heuristics for the problem most probably have poor worst-case performance. An upper bound for worst-case heuristic performance of 2n times the optimal solution is also derived. For a restricted version of the Optimal Network problem we describe a procedure whose maximum percentage of error is bounded by a constant.

A discrete transportation network design problem with combined trip distribution and assignment

Abstract: Three network design problems are formulated for optimizing discrete additions to link capacities. Trip distribution and assignment are functions of travel expenditure in each problem. A reformulation of Wilson's doubly-constrained trip distribution problem, in which entropy instead of total travel expenditure is constrained, provides zone-to-zone flows in each problem. Entropy is interpreted as a measure of zone-to-zone trip-making interaction. Computational results for a toy network are reported.

Simulation of Repetitive-Unit Construction

Abstract: Repetitive-unit construction characteristics require a flexible planning and analysis tool for proper evaluation of alternate resource allocations. Although there are numerous conventionally applied network planning techniques, none adequately model repetitive-unit construction or allow for all the important management decisions to be considered. By providing a robust structure for the problem, process interaction simulation techniques can be used for planning and decision-analysis purposes without undue sacrifice of realism or accuracy. The included multiple-unit housing example shows both the flexibility of the approach and the ability of the manager to gain much more insight into the behavior of a complex system.

Second-Order Greedy Algorithms for Centralized Teleprocessing Network Design

Abstract: We consider the problem of designing a centralized telecommunication network comprised of multipoint lines given a set of terminal locations, traffic requirements, and a common central site. The optimal solution to this problem is a capacitated minimal spanning tree. We develop a class of heuristic algorithms for the solution of this problem by imbedding existing heuristics, referred to as first-order greedy algorithms, inside a loop where small, carefully chosen sets of arcs are alternately forced in and out of the solution. The resultant procedure is shown to be superior to existing techniques, producing solutions typically 2 percent better, while requiring only a modest amount of additional computer time.

A Mixed-Integer Programming Approach to Air Cargo Fleet Planning

Abstract: This paper deals with the mathematical programming aspects of a long range planning study done for the Flying Tiger Line, an all-cargo airline. The study addressed two strategic problems: the design of the service network and the selection and deployment of the aircraft fleet. We show how the concept of a spider graph provides a natural building block for network design and present a mixed-integer programming model that enables the planner to evaluate any network constructed from spider graphs by determining the most profitable selection of aircraft and routing of cargo.

Network planning using two-stage programming under uncertainty

Abstract: The problem is to find “generating capacities” and arc capacities such that a random demand appearing regularly at the nodes should be feasible in a large percent of the cases and subject to this and further deterministic conditions, the total cost should be minimum. The cost function has two parts: the cost of the capacities and the cost of the long term average “outage” cost. As an illustration of the model the problem of planning in interconnected power systems is used. The model is a special case of one of the models introduced in [9]; it is a combination of chance constrained programming and two stage programming under uncertainty.

An overview of a network design system

Abstract: During the past few years there has been an increasing trend toward the development of on-line computer systems. By 1980 it is estimated that 70--80 percent of all larger computer installations will support some networking capability. This trend has resulted in an increasing network user population and varying applications for computer-communication networks. Furthermore, due to economics, the prevalence of single-application networks is giving way to increasing numbers of multi-application networks.

Equilibrium vs system - optimal flow: some examples

Abstract: The paper is an expository note describing certain facts about flow in a transportation network. The first is that the equilibrium flow does not necessarily minimize total cost, which implies that sometimes it may be advantageous to restrict use of part of a network. The second is that adding a new ARC to the network may increase the total cost at equilibrium (both of these facts have clear implications for network design algorithms, and both may be illustrated with examples much more transparent than the famous example of Braess. The third fact, illustrated by the example of Braess, is that adding a new arc to the network may increase the equilibrium travel cost for each individual user.(a) individual user. (Author/TRRL)

An efficient design of large-scale communication networks with a decomposition technique

Abstract: This paper presents an efficient network design method that can be used for large-scale communication networks employing both satellite and terrestrial links. The basic design problem is outlined along with mathematical models. Then a Lagrangian multiplier is used to decompose the design problem of a large-scale multinode network into that of a "coupled" set of three-node networks. This decomposition technique greatly simplifies the network design and enhances the computational efficiency. A 30-node network example is shown for illustration.

Determining deadlock exposure for a class of store and forward communication networks

Abstract: Given a network design, is the network exposed to deadlock for message buffers? This problem is addressed for a class of networks called "routed networks." A routed network is a store and forward communication network in which all transmissions follow predefined routes through the network. It is shown that a routed network is exposed to deadlock if and only if there exists a complete weighted matching of an appropriately defined bipartite graph for some subgraph of the network graph. An approach for determining whether a deadlock can occur is presented.

Network design taking into account breakdowns and traffic overloads

Abstract: Models and algorithms are presented enabling an evaluation of the traffic efficiency of a telephone network under abnormal working conditions and an optimization of network structures with reliability requirements.

Goal-programming approach to multiobjective highway network design model (abridgement)

Abstract: A new approach to the highway network design model is presented that allows comparisonsof networks on the basis of multiple incommensurable objectives with different degrees of importance. The goal-programming approach is not only capable of solving the multiobjective network design problem in a relatively efficient manner, but it can also be used to generate the multidimensional trade-off curve that provides additional important information to that provided in the two-dimensional curve derived by using the linear programming model. An example illustrates the application of the linear goal-programming model with four objectives. (Author)

Trunk demand servicing in the presence of measurement uncertainty

Abstract: Demand servicing attempts to correct existing overload conditions in the trunk network in a timely and cost-effective manner. The demand servicing procedures presented in this paper achieve this goal by taking actions that have minimal effect on the existing network configuration, account for the statistical nature of the traffic measurements, and follow the network design objectives. In comparison to existing methods, these procedures should reduce unnecessary servicing activity and improve the consistency between demand servicing and planned servicing.

Issues relating to effective lrt surface operations. resource paper

Abstract: By definition, light rail is distinguished from other rail transit modes by its ability to adapt to a broad range of surrface, not necessarily garde-separated, alignments. This paper addresses a number of issues relevant to the introduction of light rail transit, particularly in low-cost surface alignments, as an effective element of improved transit system operations. Light rail transit is a useful tool to provide maximum service at minimum cost. Network design is presented as an important but often neglected subject that is vital to establishing and maintaining the types of patterns of use successfully served by light rail transit. Edmonton, Canada's, new system illustrates the successful use of network design concetps to support a new light rail transit service. Related to network design is the relation between light rail transit service and urban development, although the case may generally have been overstated. Various low-cost approaches to right-of-way design are discussed, including approaches taken by existing light rail transit systems to speed operations on critical route segments. However, there is also evidence that non-traffic-engineering approaches to speeding service, such as self-service fares, may in some instances offer more benefits than transit-priority techniques on a systemwide basis. (Author)

Air traffic control network-planning model based on second-order markov chains

Abstract: A method designed to assess the impact of increased air traffic demand on flow rates in a network of en route air traffic control sectors is described. Given projected arrival and departure rates at airports within a given region, a second-order Markov-chain model is employed that has transition probabilities estimated from historical data. The technique is designed to serve as a planning tool and is demonstrated by using data from the New York Air Route Traffic Control Center. (Author)

Evaluation on dynamic steps of path hunting in t‐s‐t types of switching networks

Abstract: In a high-speed PCM switching system, it is possible to achieve low blocking probability and high switching efficiency due to the large number of available time-division paths between a given inlet and outlet pair. However, in order to achieve high efficiency, the central control processor of the system must perform more intensive path hunting. In conventional switching network design, the efficiency of the network is a prime concern while the control procedure for path hunting is often overlooked. Depending on the type of switching network, the trade-off between the efficiency of the network and the complexity of the control procedure should be considered. The main purpose of this paper is to evaluate the path hunting procedures for T-S-T type of time-division switching networks. The path hunting procedure will be evaluated on the basis of theoretical analysis and simulation of typical switching networks. It will be shown that there is a trade-off between the efficiency of the network and the complexity of the control procedure.

The Design of Air Quality Monitoring Networks Using an Information Content Measure.

Abstract: A statistical design methodology based on signal detection is proposed for the design of air quality monitoring networks. The information content displayed by a given network configuration is defined and suggested as a valid objective for optimal network design. Application of the methodology to an existing network of SO 2 monitors is demonstrated, and a comparison is made with an alternate statistical design criterion.