Journal:Informatica
Volume 11, Issue 2 (2000), pp. 163–178
Abstract
The aim of the given paper is a development of the direct approach used for the estimation of parameters of a closed-loop discrete-time dynamic system in the case of additive noise with outliers contaminated uniformly in it (Fig. 1). To calculate M-estimates of unknown parameters of such a system by means of processing input and noisy output observations (Fig. 2), the recursive robust H-technique based on an ordinary recursive least square (RLS) algorithm is applied here. The results of numerical simulation of closed-loop system (Fig. 3) by computer (Figs. 4–7) are given.
Journal:Informatica
Volume 11, Issue 2 (2000), pp. 145–162
Abstract
Many heuristics, such as simulated annealing, genetic algorithms, greedy randomized adaptive search procedures are stochastic. In this paper, we propose a deterministic heuristic algorithm, which is applied to the quadratic assignment problem. We refer this algorithm to as intensive search algorithm (or briefly intensive search). We tested our algorithm on the various instances from the library of the QAP instances – QAPLIB. The results obtained from the experiments show that the proposed algorithm appears superior, in many cases, to the well-known algorithm – simulated annealing.
Journal:Informatica
Volume 11, Issue 2 (2000), pp. 137–144
Abstract
In the (t,n) proxy signature scheme, the signature, originally signed by a signer, can be signed by t or more proxy signers out of a proxy group of n members. Recently, an efficient nonrepudiable threshold proxy signature scheme with known signers was proposed by H.-M. Sun. Sun's scheme has two advantages. One is nonrepudiation. The proxy group cannot deny that having signed the proxy signature. Any verifier can identify the proxy group as a real signer. The other is identifiable signers. The verifier is able to identify the actual signers in the proxy group. Also, the signers cannot deny that having generated the proxy signature. In this article, we present a cryptanalysis of the Sun's scheme. Further, we propose a secure, nonrepudiable and known signers threshold proxy signature scheme which remedies the weakness of the Sun's scheme.
Journal:Informatica
Volume 11, Issue 2 (2000), pp. 125–136
Abstract
One of the problem in business process reengineering is the identification and implementation of new workflow procedures for specific business processes, if they are not clearly defined. Analysis of unstructured (ad-hoc) activities cannot be based on traditional approaches using existing business procedures and expert knowledge. The method of business processes analysis in unstructured environments is presented in this paper. The creation of new business procedures is based on investigation of the communication acts, and application of similar workflow patterns. This method is useful in the earliest stages of business process reengineering. Preliminary analysis in ad-hoc area can be done for process identification, applying the existing knowledge baggage, reducing the analytical efforts, and creating the strong motivation for managers.
Journal:Informatica
Volume 11, Issue 2 (2000), pp. 115–124
Abstract
Influence of projection pursuit on classification errors and estimates of a posteriori probabilities from the sample is considered. Observed random variable is supposed to satisfy a multidimensional Gaussian mixture model. Presented computer simulation results show that for comparatively small sample size classification using projection pursuit algorithm gives better accuracy of estimates of a posteriori probabilities and less classification error.
Journal:Informatica
Volume 11, Issue 1 (2000), pp. 97–110
Abstract
This paper contains measures to describe the matrix impulse response sensitivity of state space multivariable systems with respect to parameter perturbations. The parameter sensitivity is defined as an integral measure of the matrix impulse response with respect to the coefficients. A state space approach is used to find a realization of impulse response that minimizes a sensitivity measure.
Journal:Informatica
Volume 11, Issue 1 (2000), pp. 87–96
Abstract
A system of two nonlinear difference-differential equations which is a mathematical model of self-regulation of glucose level in blood with time delay into consideration of insulin “age structure” is presented. The analysis carried out by qualitative and numerical methods allows us to conclude, that the mathematical model explains the functioning of the physiological system “insulin-blood glucose” in normal and pathological cases.
Journal:Informatica
Volume 11, Issue 1 (2000), pp. 71–86
Abstract
We present the capabilities of the scripting language Open PROMOL and its processor. The intention of the language is to pre-program specifications for modifying programs written in a target language. We use its processor either as a tool for developing the stand-alone reusable components or as a “component-from-the-shelf” in generative tools for generating domain specific programs. The processor itself uses the module (lexical analyser and parser) produced by Lex & Yacc as a reusable component. We describe the generation, computation, control, parameterization and gluing capabilities of the language. We compare our approach with the similar approaches known in the literature.
Journal:Informatica
Volume 11, Issue 1 (2000), pp. 65–70
Abstract
An original algorithm for transformation of finite automata to regular expressions is presented. This algorithm is based on effective graph algorithms and gives a transparent new proof of equivalence of regular expressions and finite automata.
Journal:Informatica
Volume 11, Issue 1 (2000), pp. 49–64
Abstract
Growing popularity of the mobile code requires to consider various aspects related to its security. In the aviation industry there is a case when additional information needs to be delivered to the pilot by uploading it from the ground station. It creates a need for a platform-independent solution and it raises a problem of the mobile code security as well. Organization of the security in the Base System (similar to extranets) as well as the security issues of the mobile code (or safelets for use in the aircrafts) delivered to the Remote Platform are discussed in the paper. Safelet implementation technologies and issues of code effectiveness and safety itself are discussed with Java and Juice/Oberon technologies been compared.