Journal:Informatica
Volume 15, Issue 1 (2004), pp. 45–62
Abstract
Petri net variants are widely used as a real time systems modeling technique. Recently, UML activity diagrams have been used for the same purpose, even though the syntax and semantics of activity diagrams has not been yet fully worked out. Nevertheless, activity diagrams seem very similar to Petri net semantics. UML, being the industry standard as a common object oriented modeling language needs a well‐defined semantic base for its notation. Formalization of the graphical notation enables automated processing and analysis tasks. Petri nets can provide a formal semantic framework for the UML notations plus the behavioral modeling/analysis strength needed to system designers. This paper describes the methodology for creating the model of the RT application that would allow testing the correctness of the algorithm and the fulfillment of the time constraints at the design stage using UML and Petri Nets.
Journal:Informatica
Volume 15, Issue 1 (2004), pp. 39–44
Abstract
Neural networks built of Hodgkin–Huxley neurons were examined. These structures behaved like Liquid State Machines (LSM). They could effectively process different input signals (i.e., Morse alphabet) into precisely defined output. It is also shown that there is a possibility of logical gates creation with use of Hodgkin–Huxley neurons and simple LSMs.
Journal:Informatica
Volume 15, Issue 1 (2004), pp. 23–38
Abstract
Extensive amounts of knowledge and data stored in medical databases require the development of specialized tools for storing, accessing, analysis, and effectiveness usage of stored knowledge and data. Intelligent methods such as neural networks, fuzzy sets, decision trees, and expert systems are, slowly but steadily, applied in the medical fields. Recently, rough set theory is a new intelligent technique was used for the discovery of data dependencies, data reduction, approximate set classification, and rule induction from databases.
In this paper, we present a rough set method for generating classification rules from a set of observed 360 samples of the breast cancer data. The attributes are selected, normalized and then the rough set dependency rules are generated directly from the real value attribute vector. Then the rough set reduction technique is applied to find all reducts of the data which contains the minimal subset of attributes that are associated with a class label for classification. Experimental results from applying the rough set analysis to the set of data samples are given and evaluated. In addition, the generated rules are also compared to the well‐known IDS classifier algorithm. The study showed that the theory of rough sets seems to be a useful tool for inductive learning and a valuable aid for building expert systems.
Journal:Informatica
Volume 15, Issue 1 (2004), pp. 3–22
Abstract
The paper deals with the intelligent functional model for optimizing the product design and its manufacturing process in hybrid manufacturing systems consisting of people, machines and computers. The knowledge‐based framework of an intelligent functional model has been developed. It furnishes the possibility for a product designer and manufacturer to find an optimal production plan in the early stage of the product design. The mathematical model formalization is provided. A consecutive optimization scheme has been applied for selecting an optimal alternative of a product design and its production plan. The proposed model is being implemented both in industry and university education process.
Journal:Informatica
Volume 14, Issue 4 (2003), pp. 551–558
Abstract
Recently, Tseng et al. proposed an improvement on Peyravian and Zunic's protected password transmission scheme and protected changing scheme to remove some security flaws. However, as we will point out in this paper, any adversary can intercept the request for changing the password sent by a legal user and modify it with a wrong password. Furthermore, we shall also propose an improved version of their protected password changing scheme to help it out of the trouble.
Journal:Informatica
Volume 14, Issue 4 (2003), pp. 541–550
Abstract
The paper deals with the analysis of the two survival models of the accelerated failure‐time using two‐parametrical log‐logistic and Weibull distributions, and survival models using conditional generalized Weibull, log‐logistic, and Smith and Bain distributions. The observed survival (number of deaths during the 30‐year follow‐up period among the study cohort) and the survival predicted by regression models (predicted number of deaths for the same period of time) were compared. Data on deaths occurring in random sample of men were obtained from the death register of the city of Kaunas. The best agreement between the predicted and observed survival was obtained with one of the modified Smith and Bain models.
Journal:Informatica
Volume 14, Issue 4 (2003), pp. 529–540
Abstract
Cataract is very frequent disease of human eye and the diagnosis of this disease is not difficult. However, it is important to describe it quantitatively, but it is difficult using only the slit lamp. Ultrasound examinations are widely used in ophthalmology. Piezoelectric crystals generate ultrasound waves of 5–50 MHz. Short pulses of 2 to 3 cycles are sent from transducer into the eye. These pulses go through the tissues of the eye with the speed that is inversely proportional to the density and elasticity of the eye. Acoustic parameters of biologic tissues are described by velocity and attenuation coefficient. It is known that in soft tissues the attenuation coefficient is approximately proportional to the frequency – high frequency components of echoes are attenuated more than the lower frequency components. Results of ultrasound attenuation characteristics of human nuclear cataract are presented. It was shown that ultrasound attenuation of nuclear cataract could be used as “second opinion” for physicians decision support.
Journal:Informatica
Volume 14, Issue 4 (2003), pp. 515–528
Abstract
The paper presents the comparison of fuzzy conclusions derived from the use of t‐norms with the fuzzy conclusions derived from the use of H‐norm. The idea was to examine the application of H‐logical norm to fuzzy reasoning, which is not monotonious while it is known that t‐norms used in fuzzy reasoning have the characteristic of monotonicity. The comparison of fuzzy conclusions was performed by the use of coherence measure. The research was carried out on a relatively small number of examples (nine) and it was shown that the fuzzy conclusions derived from the use of H‐norm were the closest to the fuzzy conclusions derived from TL‐norm.
Journal:Informatica
Volume 14, Issue 4 (2003), pp. 497–514
Abstract
The quadratic assignment problem (QAP) is one of the well‐known combinatorial optimization problems and is known for its various applications. In this paper, we propose a modified simulated annealing algorithm for the QAP – M‐SA‐QAP. The novelty of the proposed algorithm is an advanced formula of calculation of the initial and final temperatures, as well as an original cooling schedule with oscillation, i.e., periodical decreasing and increasing of the temperature. In addition, in order to improve the results obtained, the simulated annealing algorithm is combined with a tabu search approach based algorithm. We tested our algorithm on a number of instances from the library of the QAP instances – QAPLIB. The results obtained from the experiments show that the proposed algorithm appears to be superior to earlier versions of the simulated annealing for the QAP. The power of M‐SA‐QAP is also corroborated by the fact that the new best known solution was found for the one of the largest QAP instances – THO150.
Journal:Informatica
Volume 14, Issue 4 (2003), pp. 487–496
Abstract
The paper deals with the use of dynamic programming for word endpoint detection in isolated word recognition. Endpoint detection is based on likelihood maximization. Expectation maximization approach is used to deal with the problem of unknown parameters. Speech signal and background noise energy is used as features for making decision. Performance of the proposed approach was evaluated using isolated Lithuanian words speech corpus.