Journal:Informatica
Volume 5, Issues 3-4 (1994), pp. 338–350
Abstract
In this paper we consider the numerical solution of the large system of nonlinear differential equations. We assume that the system simulates the semiconductor circuit. We apply the well known event driven techniques to get some approximation of solution fast. We extend those techniques by considering pairs of nodes, instead of single nodes, as usual. The “pairwise” solution is more efficient in tightly coupled circuits. The improvement of efficiency of solution is important optimizing the parameters of circuits. In many cases we need the global optimization of equation parameters. Then, the modeling speed could be the main factor of successful application.
Journal:Informatica
Volume 5, Issues 3-4 (1994), pp. 324–337
Abstract
The problem of the parameters estimation of quasihomogeneous autoregressive random field is considered. An algorithm is proposed for the parameter estimation of certain classes of such fields.
Journal:Informatica
Volume 5, Issues 3-4 (1994), pp. 297–323
Abstract
The convergence properties of some LOD schemes are considered. New stability estimates with respect to boundary conditions are proved. These results are used to investigate the accuracy of LOD schemes when no special boundary correction technique is used for the realization of LOD schemes. The accuracy of LOD schemes with corrected boundary conditions is also investigated. Results of the computational experiment are given.
Journal:Informatica
Volume 5, Issues 3-4 (1994), pp. 283–296
Abstract
In this paper we present the development of the nationwide information infrastructure in Lithuania. The paper describes the general framework of Lithuania's information infrastructure, basic philosophy behind it, and the current solution of the problem from the point of view registers, data network, standards and application systems.
Journal:Informatica
Volume 5, Issues 3-4 (1994), pp. 261–282
Abstract
Control laws' design strategies in order to stabilize integro-differential systems with delays are developed by using an extended system and the delay measure.
Journal:Informatica
Volume 5, Issues 1-2 (1994), pp. 241–255
Abstract
Neural networks are often characterized as highly nonlinear systems of fairly large amount of parameters (in order of 103 – 104). This fact makes the optimization of parameters to be a nontrivial problem. But the astonishing moment is that the local optimization technique is widely used and yields reliable convergence in many cases. Obviously, the optimization of neural networks is high-dimensional, multi-extremal problem, so, as usual, the global optimization methods would be applied in this case. On the basis of Perceptron-like unit (which is the building block for the most architectures of neural networks) we analyze why the local optimization technique is so successful in the field of neural networks. The result is that a linear approximation of the neural network can be sufficient to evaluate the start point for the local optimization procedure in the nonlinear regime. This result can help in developing faster and more robust algorithms for the optimization of neural network parameters.
Journal:Informatica
Volume 5, Issues 1-2 (1994), pp. 231–240
Abstract
The problem of mathematical modelling and simulating of two-dimensional (2D) random fields, using space autoregressive models, is analyzed. Algorithms for the estimation of parameters of models, procedures for finding correlation coefficients and for synthesis of the realizations of given parameter fields are presented.
Journal:Informatica
Volume 5, Issues 1-2 (1994), pp. 211–230
Abstract
The paper deals with a simple model of the competition of two queuing systems, providing the same service. Each system may vary its service price and its service rate. The customers choose the system with less total service price, that depends on the waiting time and on the service price. The possibility for the existence of equilibrium is investigated. Simple cases are investigated analytically. It is shown that the Nash equilibrium exists in special cases only. A modification of the Stakelberg equilibrium is proposed as a model of competition with a prognosis. This prognosis helps form more stable prices and more stable strategies of competitors. The case of social economics is investigated, too. The dynamics of the competition of more realistic stochastic queuing systems is investigated by Monte Carlo simulation. The simulative analysis is realized by means of a rule-based simulation system.
Journal:Informatica
Volume 5, Issues 1-2 (1994), pp. 189–210
Abstract
In the previous papers (Novovičova, 1987; Pupeikis 1991) the problem of recursive least square (RLS) estimation of dynamic systems parameters in the presence of outliers in observations has been considered, when the filter, generating an additive noise, has a transfer function of a particular form, see Fig. 1, 2. The aim of the given paper is the development of well-known classical techniques for robust on-line estimation of unknown parameters of linear dynamic systems in the case of additive noises with different transfer functions. In this connection various ordinary recursive procedures, see Fig. 2–6, are worked out when systems' output is corrupted by the correlated noise containing outliers. The results of numerical simulation by IBM PC/AT (Table 1) are given.
Journal:Informatica
Volume 5, Issues 1-2 (1994), pp. 175–188
Abstract
An essentially new method for discrete sequential detection of abrupt or slow multiple changes in several unknown properties of random processes is considered. The method is based on a sequential nonlinear mapping into two-dimensional vectors of many-dimensional vectors of parameters which describe the properties of random process. The mapping error function is chosen and the expressions for sequential nonlinear mapping are presented along with some experimental results. Theoretical minimum amount of at the very beginning simultaneously mapped vectors is obtained.