Journal:Informatica
Volume 12, Issue 3 (2001), pp. 431–438
Abstract
The sequential nonlinear mapping is suitable for sequential detection of states of dynamic systems (Montvilas, 1999a). In addition, it can indicate the undesirable states and even the damages of dynamic systems. The last is complicated when the damage is caused by a small changing of respective parameter describing the state. In the paper the problem of nonlinear mapping to be sensitive for the small changing of parameters and the problem related with dimensionality of parameters are solved by using a special pre-processing of data. Examples are given.
Journal:Informatica
Volume 12, Issue 3 (2001), pp. 413–430
Abstract
The article presents results of the national survey on teaching and studying informatics at Grades 11 and 12 in the Lithuanian secondary school. This study explores the influence of different factors on students' achievements in informatics. The purpose of this work is to study the interaction between various characteristics of student, teacher and school, and factors of studying and teaching informatics and their joint influence on students' achievements in informatics. In addition, the article explores and contrasts the casual influence structures on the students' knowledge of two different branches of informatics: computer application and programming. To explore these interrelations, PLSpath analytic procedure has been used.
Journal:Informatica
Volume 12, Issue 3 (2001), pp. 385–412
Abstract
Filtering of feature matches is heuristic method aimed to reduce the number of feasible matches and is widely employed in different image registration algorithms based on local features. In this paper we propose to interpret the filtering process as an optimal classification of the matches into the correct or incorrect match classes. The statistics, according to which the filtering is performed, uses differences of the geometrical invariants obtained from ordered sets of local features (composite features) of proper cardinality. Further, we examine some computationally efficient implementation schemes of the classification. Under the assumption of Gaussian measurement error, the conditional distribution densities of invariants can be approximated by well-known linearization approach. Experimental evidences obtained from fingerprint identification, which confirm viability of the proposed approach, are presented.
Journal:Informatica
Volume 12, Issue 3 (2001), pp. 373–384
Abstract
In this paper our attention is focused on the study of the properties for some families of contextual languages with catenation (see Fortiş, 1999, also Păun, 1982; Păun, 1997). Also, we are defining and analyzing some new properties characteristic to these families of languages. Using these properties we are able to establish some necessary conditions, and some pumping properties for families of contextual languages with catenation.
Journal:Informatica
Volume 12, Issue 3 (2001), pp. 347–372
Abstract
This paper presents the set of verification rules to detect faults in specification of model of computerized information system. Computerized information system model is specified using Enterprise modeling approach, which integrates static and dynamic dependencies. Typical communication action loop is a basic construct of Enterprise modeling approach. Actions, which process data resources of computerized information system, are analyzed.
Journal:Informatica
Volume 12, Issue 2 (2001), pp. 337–342
Abstract
The distribution of neutron population in nuclear reactor is described by using transport equations. One of possible approximations of neutron transport equation is given by the neutron diffusion equation. The paper presents numerical solution method of one group neutron diffusion equation with one group of delayed neutrons.
Journal:Informatica
Volume 12, Issue 2 (2001), pp. 315–336
Abstract
The paper deals with automatic stressing of the Lithuanian text. In the previous work the author presented an algorithm for automatic stressing of the Lithuanian text on the basis of a dictionary. The aim of the present work is to improve the above mentioned algorithm by including formal stressing rules for nouns and adjectives. By means of these rules such words as diminutives, names and degrees of adjectives that are not present in the dictionary may be stressed. The work analyses when it is more convenient to formulate rules manually and when to generate them automatically. A method for formulating rules manually has been described and a set of such rules has been presented. Besides the algorithm for generating stressing rules with the help of a dictionary of stems of nouns and adjectives has been given.
Journal:Informatica
Volume 12, Issue 2 (2001), pp. 303–314
Abstract
In the practice of metal treatment by cutting it is frequently necessary to deal with self-excited oscillations of the cutting tool, treated detail and units of the machine tool. In this paper are presented differential equations with the delay of self-excited oscillations. The linear analysis is performed by the method of D-expansion. There is chosen an area of asymptotically stability and area D2. It is prove that, in the area D2 the stable periodical solution appears. The non-linear analysis is performed by the theory of bifurcation. The computational experiment of metal cutting process and results of these experiments are presented.
Journal:Informatica
Volume 12, Issue 2 (2001), pp. 297–302
Abstract
Yamaguchi, Okayama, and Miyahara proposed a simple but efficient authentication system, SPLICE/AS. In this article, we show that their method is vulnerable to the guessing attack. An attacker can obtain the password, private-key, and public-key of the user. To overcome the vulnerability of SPLICE/AS to the guessing attack, we propose an improvement of their system. In our scheme, we not only prevent the guessing attack to obtain secret messages but also enhance the security of the SPLICE/AS authentication system in WIDE.
Journal:Informatica
Volume 12, Issue 2 (2001), pp. 285–296
Abstract
Amidst the debate on the relative merits of push versus pull technologies, the role of information dynamics over the Internet in shaping truly compelling use of the medium for electronic commerce is being recognized. Focused Broadcasting, a business model of matching classified and want ads using the World Wide Web, is positioned as an example of a balanced approach whose success may be predictable based on market research and analysis. This article reports on a study conducted in New Zealand of Internet user attitudes toward this type of service.