No. 3 (2004)
Published:
2004-09-30
ARTICLES FROM THIS ISSUE
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Direct method of hierarchical nonlinear optimization - reassessment after 30 years
Abstract
We consider the optimization problems which may be solved by the direct decomposition method. It is possible when the performance index is a monotone function of other performance indices, which depend on two subsets of decision variables: an individual for every inner performance index and a common one for all. Such problems may be treated as a generalization of separable problems with the additive cost and constraints functions. In the paper both the underlying theory and the basic numerical techniques are presented and compared. A special attention is paid to the guarantees of convergence in different classes of problems and to the effectiveness of calculations.
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ASimJava: a Java-based library for distributed simulation
Abstract
The paper describes the design, performance and applications of ASimJava, a Java-based library for distributed simulation of large networks. The important issues associated with the implementation of parallel and distributed simulation are discussed. The focus is on the effectiveness of different synchronization protocols implemented in ASimJava. The practical example - computer network simulation - is provided to illustrate the operation of the presented software tool.
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Data analysis and flow graphs
Abstract
In this paper we present a new approach to data analysis based on flow distribution study in a flow network. Branches of the flow graph are interpreted as decision rules, whereas the flow graph is supposed to describe a decision algorithm. We propose to model decision processes as flow graphs and analyze decisions in terms of flow spreading in the graph.
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Probes for fault localization in computer networks
Abstract
Fault localization is a process of isolating faults responsible for the observable malfunctioning of the managed system. This paper reviews some existing approaches of this process and improves one of described techniques - the probing. Probes are test transactions that can be actively selected and sent through the network. Suggested innovations include: mixed (passive and active) probing, partitioning used for probe selection, logical detection of probing results, and adaptive, sequential probing.
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Site selection for waste disposal through spatial multiple criteria decision analysis
Abstract
This article deals with the application of spatial multiple criteria evaluation (SMCE) concepts and methods to support identification and selection of proper sites for waste disposal. The process makes use of a recently developed SMCE module, integrated into ITC`s existing geographic information system called ILWIS. This module supports application of SMCE in planning and decision making processes through several compensatory and non-compensatory approaches, allowing inclusion of the spatial and thematic priority of decision makers. To demonstrate the process, a landfill site selection problem around the town of Chinchina, in Colombia, is used as an example. Based on different objectives, a spatial data set consisting of several map layers, e.g., land use, geological, landslide distribution, etc., is made available and used for modeling the site selection process.
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Multicriteria analysis for behavioral segmentation
Abstract
Behavioral segmentation is a process of finding the groups of clients with similar behavioral patterns. The basic tool for segmentation is a clustering algorithm. However, the clusters generated by the algorithm depend on the preprocessing steps as well as parameters of the algorithm. Therefore, there are many possibilities of dividing the clients into segments and it is a subjective process. In this paper we will focus on application on multicriteria analysis for selecting the best partition of clients into segments.
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A new methodology of accounting for uncertainty factors in multiple criteria decision making problems
Abstract
A new approach is proposed to select a predetermined number of ``reasonable`` (the best in a certain sense) alternatives from the considerable (maybe a vast) set of initial alternatives according to an arbitrary number of optimization criteria and accounting for uncertainty factors. The approach is based on using a special intuitive methodology, developed to account for uncertainty factors when solving such multiple criteria decision making (MCDM) problems. This methodology is based on performing multi-variant computations (MVC) and finding their ``stable-optimal`` solutions, and it`s realized as a multi-level hierarchical system of MVC series. It`s possible to use this methodology for solving various real problems.
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Exploring agent-based wireless business models and decision support applications in an airport environment
Abstract
This paper describes an intelligent communication and decision support system for providing wireless services in an airport environment. A novel agent-based business model is proposed and the value chain is analysed for wireless applications. This system is studied and developed within the scope of the IST ADAMANT project, where the Athens International Airport (AIA) is used as the trial environment. First of all, a set of advanced, realistic decision support application scenarios enhancing the airport facilities both for the passengers and for the airport staff is identified. Most of the applications can be summarised as location-based personalised services. They refer both to airport internal users and to passenger users. In order to provide these services, location-sensitive service level agreements (SLAs) and radio resource management (RRM) are introduced. The design of such a system is envisaged based on a generic, multi-agent architecture, which is also presented in this paper.
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Towards broadband global optical and wireless networking
Abstract
This paper presents a novel, non-conventional approach to the future optical and wireless hybrid transport network, capable of supporting dominant kinds of traffic, i.e., voice/real time, wireless and packet data traffic in a single transport network. The proposed model combines different technologies as connection and connectionless networks, optical cable and wireless (microwave/millimetre wave or optical wireless), being suitable for a variety of purposes and services in order to achieve global broadband networking features. Our new networking model contains an extension to wireless world in order to achieve mobility and personalisation of connection. From the networking point of view it consists of an upgrade of real-time traffic with the microwave modulated optical wave, in order to carry out conventional mobile wireless signals via optical fibres over long distances and without significant distortion. The whole available bandwidth can be fully exploited in the hybrid network. In the IP part of the network the quality of service (QoS) can be differentiated for various classes of packets and network reliability/survivability can be categorised for the whole hybrid network. This proposal combines complete and revolutionary shift to packet traffic with smooth evolutionary upgrades. We believe the model presented here is a powerful tool to trace the future evolution of telecommunications worldwide for the next 25 years.
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Influence of common path on availability of ring network
Abstract
This paper analyses availability of the ring network which uses the path protection switching (sub-network connection protection - SNCP). Influence of the common path on the ring network availability is analyzed. Data regarding failures of optical fibre cables and equipment used for calculations have been obtained during years-long observation of SDH network in HT Mostar as well as from manufacturers.
