Journal:Informatica
Volume 10, Issue 3 (1999), pp. 297–312
Abstract
In the previous paper (Pupeikis, 1998), the problem of recursive estimation of the state of linear dynamic systems, described by an autoregressive model (AR), in the presence of time-varying outliers in observations to be processed has been considered. An approach to the robust recursive state estimation has been obtained and proved by estimating the real chemical process (Box and Jenkins, 1970). The aim of the given paper is the development of the abovementioned approach for the robust recursive state estimation of an autoregressive-moving average (ARMA) process in a case of additive noises with patchy outliers. The results of numerical simulation and the state estimation of the AR model (Figs. 1–4) and the real chemical process, described by the ARMA model, which is chosen from the same book of Box and Jenkins (Figs. 5–8) are given.
Journal:Informatica
Volume 10, Issue 3 (1999), pp. 289–296
Abstract
A new method for a creation of the information system for sequential identification of states of technological processes or other dynamic systems for their supervision and control is considered. The states of dynamic system can be unknown and can change themselves abruptly or slowly. The method is based on a sequential nonlinear mapping of many-dimensional vectors of parameters (collection of which describes the present state of dynamic systems) into two-dimensional vectors in order to reflect the states and their changes on the PC screen and to observe the situation by means of computer. The mapping error function is chosen and expressions for sequential nonlinear mapping are obtained. The mapping preserves the inner structure of distances among the vectors. Examples are given.
Journal:Informatica
Volume 10, Issue 3 (1999), pp. 275–288
Abstract
As a significant segment of the Information Industries, classified advertising can be a prime example of how conventional businesses, rather than being simply transplanted to the New (digital) Media, may indeed be transformed for future growth. To be successful, such transformations must be able to take full advantage of the defining features of the emerging information infrastructure for innovative creation of economic value. Focused Broadcasting, a class of service for matching classified and want ads using the World Wide Web, is an approach that balances the push-pull dynamics of information over the Internet. Applying the concept of product introduction with complementary network externalities, a dynamic model is formulated to simulate the potential growth of such business in cyberspace. Robustness of the model is demonstrated.
Journal:Informatica
Volume 10, Issue 2 (1999), pp. 245–269
Abstract
Structurization of the sample covariance matrix reduces the number of the parameters to be estimated and, in a case the structurization assumptions are correct, improves small sample properties of a statistical linear classifier. Structured estimates of the sample covariance matrix are used to decorellate and scale the data, and to train a single layer perceptron classifier afterwards. In most from ten real world pattern classification problems tested, the structurization methodology applied together with the data transformations and subsequent use of the optimally stopped single layer perceptron resulted in a significant gain in comparison with the best statistical linear classifier – the regularized discriminant analysis.
Journal:Informatica
Volume 10, Issue 2 (1999), pp. 231–244
Abstract
In this paper two popular time series prediction methods – the Auto Regression Moving Average (ARMA) and the multilayer perceptron (MLP) – are compared while forecasting seven real world economical time series. It is shown that the prediction accuracy of both methods is poor in ill-structured problems. In the well-structured cases, when prediction accuracy is high, the MLP predicts better providing lower mean prediction error.
Journal:Informatica
Volume 10, Issue 2 (1999), pp. 219–230
Abstract
This paper presents several results associated with the Wright's generalized hypergeometric function, depicting their interesting characterization properties. Special cases are also pointed out.
Journal:Informatica
Volume 10, Issue 2 (1999), pp. 203–218
Abstract
We have studied the design documentation for two industrial software modules to see if they apply ideas corresponding to contracts, as introduced by Bertrand Meyer, either in an intuitive or in a formal way. They did not, and we identified this fact to be a potential risk factor. This paper presents one of the modules studied, consisting of a sequence of switching sections. Starting from this case study, the paper also discusses how switching sections in general can be designed using contracts in order to increase the semantic integrity of the module as a whole.
Journal:Informatica
Volume 10, Issue 2 (1999), pp. 189–202
Abstract
In this paper the framework for business object modeling with focus on distributed enterprise is proposed. It is based on Business Object Architecture, UML and Catalysis method. Business Object Architecture is methodology bringing business semantics to component-based development – the next generation of object-oriented methodology. Basic modeling concepts are business objects, business processes and business rules. Process of business process modeling with Business Objects is described and generic modeling patterns are presented. The framework is illustrated via work effort process modeling.
Journal:Informatica
Volume 10, Issue 2 (1999), pp. 171–188
Abstract
This paper addresses the study of the speech intelligibility enhancement. The speech model, noise sources, perceptual aspects of speech, and performance evaluation are reviewed. The intelligibility enhancement system based on spectral subtraction technique is investigated. Spectral density estimation device based on the algorithm of smoothed periodograms is analysed. Determination of the silence intervals, efficiency of the silence intervals determination, and signal to noise ratio evaluation are discussed. Speech intelligibility enhancement device is described.
Journal:Informatica
Volume 10, Issue 2 (1999), pp. 161–170
Abstract
In this paper we consider parallel numerical integration algorithms for multi-dimensional integrals. A new hyper-rectangle selection strategy is proposed for the implementation of globally adaptive parallel quadrature algorithms. The well known master-slave parallel algorithm prototype is used for the realization of the algorithm. Numerical results on the SP2 computer and on a cluster of workstations are reported. A test problem where the integrand function has a strong corner singularity is investigated. A modified parallel integration algorithm is proposed in which a list of subproblems is distributed among slave processors.