Network Design Process Research Articles

Synthesis of mass exchange network for batch processes—Part I: Utility targeting

Synthesis of optimal mass exchange network (MEN) for continuous processes based on Pinch Analysis has been rather well established. In contrast, very little work has been done on mass exchange network synthesis (MENS) for batch process systems. The batch process systems referred to in this work can be defined as processes which operate discontinuously and deliver the products in discrete amounts, with frequent starts and stops. There is a clear need to develop a MENS procedure for batch process systems which are industrially very common as well as important. Techniques developed in this paper for the batch MENS involved the first key steps in the synthesis task, i.e. setting the utility targets ahead of batch MEN design. The utility-targeting approach employs the vertical and horizontal cascading approaches in a newly developed tool, i.e. time-dependent composition interval table that has been adapted from heat exchange network synthesis for batch processes. Prior to MEN design, the targeting procedure establishes the minimum utility (solvent) and mass storage targets for a maximum mass recovery network. These targets are essential for network design and batch process rescheduling.

EVOLUTIONARY NETWORK DESIGN: HYBRID GENETIC ALGORITHMS APPROACH

In recent years we have evidenced an extensive effort in the development of computer communication networks, which have deeply integrated in human being's everyday life. One of the important aspects of the network design process is the topological design problem involved in establishing a communication network. However, with the increase of the problem scale, the conventional techniques are facing the challenge to effectively and efficiently solve those complicated network design problems. In this article, we give a brief survey on our recent research works of network design problems by using genetic algorithms (GAs), such as, multistage process planning problem, fixed charge transportation problem, minimum spanning tree problem, centralized network design, and local area network design, shortest path problem, minimum cost maximum flow problem, and optimal scheduling problems based on network topology. All these problems are illustrated from the point of genetic representation encoding skill and the genetic operators with hybrid strategies. Numerical experiments show the effectiveness and efficiency of such kind of GA-based approach.

Evaluation of an Artificial Neural Network Technique Applied to Multiple-Sensor Weigh-in-Motion Systems

Weigh-in-motion (WIM) accuracy in measuring static axle loads is affected by vehicle dynamics and noise. Neural networks can identify underlying relationships, such as the spatial repeatability in axle dynamics, and can efficiently remove noise. Furthermore, they can adapt to changing circumstances (e.g., traffic characteristics, road profile, or sensor failure), unlike conventional WIM calibration algorithms. The paper performance of a multilayer feed-forward artificial neural network algorithm applied to a multiple-sensor WIM is analyzed. Numerical simulations of the axle forces applied on a smooth road profile are used to train, validate, and test the artificial neural network algorithm. This dynamic axle load variation is predicted with the vehicle simulation model VESYM. The mechanical parameters of the truck models and their speeds are randomly varied over a range established from real traffic measurements. Once the theoretical WIM data are obtained at the sensor locations, the measurements are artificially corrupted with noise up to the typical level of WIM accuracy. Details are given on the process of the neural network design, the size of the training sample, and the length of the training period. The artificial neural networks approach resulted in higher accuracy than the traditional average-based calibration method, especially at high noise levels. As a result, it shows promise for estimating static axle loads from multiple WIM measurements.

A Design of Multilayer Perceptron for Camera Calibration

In this paper a new design of multi-layer perceptron(MLP) for camera calibration is proposed. Most existing techniques determine a transformation from 3D spatial points to their image points and camera parameters are tried to be estimated from the transformation. The technique proposed here, on the other hand, determines rays of sight uniquely from image points and parameters are estimated from the relationship using an MLP. By this approach projection and back-projection can be done more straightforwardly. Being based on a geometric model, a network design process becomes less ambiguous, which is a clear merit compared to other neural net based techniques. An MLP designed according to the technique proposed showed fast and stable learning in tests under various conditions.

Network design techniques using adapted genetic algorithms

In recent years we have evidenced an extensive effort in the development of computer communication networks, which have deeply integrated in human being's everyday life. One of important aspects of the network design process is the topological design problem involved in establishing a communication network. However, with the increase of the problem scale, the conventional techniques are facing the challenge to effectively and efficiently solve those complicated network design problems. In this article, we summarized recent research works on network design problems by using genetic algorithms (GAs), including multistage process planning (MPP) problem, fixed charge transportation problem (fc-TP), minimum spanning tree problem, centralized network design, local area network (LAN) design and shortest path problem. All these problems are illustrated from the point of genetic representation encoding skill and the genetic operators with hybrid strategies. Large quantities of numerical experiments show the effectiveness and efficiency of such kind of GA-based approach.

A Value-added Model for E-Commerce

Given the transaction as a basic unit of analysis, a comprehensive model of value added roles can be distilled from the synthesis of network design and business process models. Any given implementation may be seen as a cluster of roles that add value for the buyer and produce revenue for the seller. The general representation of the model suggests that there are four common classes of roles from which the possibilities for adding value through e-commerce can be derived: Organic, Structural, Functional and Commercial. These roles are defined and discussed, beginning with the organic distinction of Markets vs. Hierarchies. This comprehensive model provides a solid foundation for the systematic analysis of e-commerce implementations.

Applying GIS and Combinatorial Optimization to Fiber DeploymentPlans

A decision-support system for the Fiber Deployment Plan problem is developed for the telephone cable network design in the telecommunications industry. The system employs a Geographic Information System (GIS) and uses combinatorial optimization techniques as its components. A mathematical combinatorial optimization model is formulated for the problem and a heuristic solution procedure is developed for the model. A GIS within the ESRI Arc/INFO and ArcView environment is used to provide data needed to build the mathematical combinatorial optimization model and to furnish an interface between the users and computers in data input and in solution result display. Combinatorial optimization techniques are used in the heuristic solution procedure to find good solutions for the optimization model. The developed decision-support system has been used to real life problems and has resulted in tremendous improvements in the telephone cable network design process. The user is completely satisfied with the performance of the system.

Spatial traffic estimation and characterization for mobile communication network design

This paper presents a new method for the estimation and characterization of the expected teletraffic in mobile communication networks. The method considers the teletraffic from the network viewpoint. The traffic estimation is based on the geographic traffic model, which obeys the geographical and demographical factors for the demand for mobile communication services. For the spatial teletraffic characterization, a novel representation technique is introduced which uses the notion of discrete demand nodes. We show how the information in geographical information systems can be used to estimate the teletraffic demand in an early phase of the network design process. Additionally, we outline how the discrete demand node representation facilitates the application of demand-based automatic mobile network design algorithms.

Design for performance of broadband signalling and services

As the telecommunications industry evolves, and broadband services start to arrive, customers are increasingly coming to expect the perception of instantaneous access to service providers, together with transparency to network failures. System performance dictates that response times need to be minimised, sufficient redundant capacity be installed in case of failure, and controls be embedded within the design to manage the exceptional situations (such as media-stimulated events) that continually threaten network integrity. A vital part of this system is the broadband signalling network, which underpins the dialogue with the customer, and which enables the delivery of the service. Network design based on a 'top-down', 'end-to-end' methodology plays a fundamental role in delivering solutions that meet customers' performance needs. Simple, approximate performance models at an early stage in this life cycle are valuable to uncover major performance problems which affect the design of the architecture. Performance issues identified can then be fed back into the design process in an iterative way, to ensure that the design solution will conform to performance requirements.This paper outlines performance studies of a number of design scenarios for providing broadband services. These studies consider interactive multimedia services, looking at service demand, physical network topology, signalling message flows, the mapping of functional entities to physical components, and routeing, as part of the network design process. The most significant performance issues identified relate to bottle-necks, capacity requirements, and load-dependent response times as perceived by the customer.

Design of survivable communications networks under performance constraints

The authors describe a network design algorithm that uses a set of deterministic connectivity measures which result in topologically survivable network designs that also meet processing and performance requirements. The authors briefly describe some applicable graph theoretic concepts and recently developed connectivity measures. They describe systematic procedures for improving the topological survivability of a network, and the overall network design process. A design example is presented. >

Control and optimization methods in communication network problems

The authors focus on two areas of communication network design in which methods of control and optimization theory have proven useful. These are the area of multiple access communication (for networks with shared links such as radio networks and local area networks) and the area of network routing (for networks with point-to-point interconnections). They review a few selected problems in each area to show the role of the control concepts involved and then proceed to identify other areas of communication network design in which the same control theoretic and optimization methodology may be applicable and useful. They attempt to bring to the attention of the control systems community the numerous instances of problems arising in the pure communication network design process that can benefit from the attention and the capabilities of this community. >

A Strategy for Network Planning and Control

Abstract Planning and implementing a data communications network is a complex task involving organizational as well as technical issues. The network design process must be integrated with the organization's business goals and strategies. Because network planning, implementation, and maintenance require skills not usually found in a batch-oriented DP environment, training is critical.

Topological design of centralized computer networks—formulations and algorithms

AbstractIn recent years we have evidenced an extensive effort in the development of computer communication networks. One of the important aspects of the network design process is the solution of the topological design questions involved in establishing a communication network. In this article, formulations are presented for a variety of centralized network design problems such as the minimal spanning tree problem, capacitated and degree constrained minimal spanning tree problems, The Telpak problem, and, heterogeneous network design problems. The applicability of these formulations to algorithmic development is demonstrated by developing an efficient algorithm for solving the degree constrained minimal spanning tree problem. Computational results are reported for 630 test problems. A Bender's decomposition procedure is developed and tested for the capacitated minimal spanning tree problem with less favorable results.