Journal:Informatica
Volume 11, Issue 3 (2000), pp. 257–268
Abstract
Fingerprint ridge frequency is a global feature, which is most prominently different in fingerprints of men and woman, and it also changes within the maturing period of a person. This paper proposes the method of fingerprint pre-classification, based on the ridge frequency replacement by the density of edge points of the ridge boundary. This method is to be used after applying the common steps in most fingerprint matching algorithms, namely the fingerprint image filtering, binarization and marking of good/bad image areas. The experimental performance evaluation of fingerprint pre-classification is presented. We have found that fingerprint pre-classification using the fingerprint ridge edges density is possible, and it enables to preliminary reject part of the fingerprints without heavy loss of the recognition quality. The paper presents the evaluation of two sources of fingerprint ridge edges density variability: a) different finger pressure during the fingerprint scanning, b) different distance between the geometrical center of the fingerprint and position of the fingerprint fragment.
Journal:Informatica
Volume 11, Issue 3 (2000), pp. 243–256
Abstract
This paper deals with maximum likelihood and least square segmentation of autoregressive random sequences with abruptly changing parameters. Conditional distribution of the observations has been derived. Objective function was modified to the form suitable to apply dynamic programming method for its optimization. Expressions of Bellman functions for this case were obtained. Performance of presented approach is illustrated with simulation examples and segmentation of speech signals examples.
Journal:Informatica
Volume 11, Issue 2 (2000), pp. 219–232
Abstract
Color constancy is the perceived stability of the color of objects under different illuminants. Four-layer neural network for color constancy has been developed. It has separate input channels for the test chip and for the background. Input of network was RGB receptors. Second layer consisted of color opponent cells and output have three neurons signaling x, y, Y coordinates (1931 CIE). Network was trained with the back-propagation algorithm. For training and testing we used nine illuminants with wide spectrum. Neural network was able to achieve color constancy. Input of background coordinates and nonlinearity of network have crucial influence for training.
Journal:Informatica
Volume 11, Issue 2 (2000), pp. 195–218
Abstract
Two models for an age-structured nonlimited population dynamics with maternal care of offspring are presented. One of them deals with a bisexual population and includes a harmonic mean type mating of sexes and females' pregnancy. The other one describes dynamics of an asexual population. Migration is not taken into account. The existence and uniqueness theorem for the general case of vital rates is proved, the extinction and growth of the population are considered, and a class of the product (separable) solutions is obtained for these two models. The long-time behavior of the asexual population is obtained in the stationary case of vital rates.
Journal:Informatica
Volume 11, Issue 2 (2000), pp. 179–194
Abstract
A concept of regional technological cooperation is developed based on a cooperative game theoretic model, in which a plan of payoff distributions induces an agreement that is acceptable to each participant. Under certain conditions, the underlying game is shown to be convex, and hence to have a nonempty core with the Shapley value allocations belonging to the core. A compensation scheme is devised based on the Shapley value allocations, whereby participants who enjoy a greater payoff with respect to the technological cooperation compensate the participants who receive a relatively lesser payoff via cooperation. In this manner, regional technological cooperation can bring overall benefits to all the involved players in the game. Some insightful examples are provided to illustrate the methodological concept.
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.