Informatica

In this paper, a new multi-criteria decision-making procedure is presented, which captures preferential information in the form of the threshold model. It is based on the ELECTRE-like sorting analysis restricted by the localization principle, which enables high adaptability of the decision model and reduces the cognitive load imposed on the decision-makers. It lays the foundation for the introduction of three concepts that have been previously insufficiently supported by outranking methods – semiautomatic derivation of criteria weights according to the selective effects of discordance and veto thresholds, convergent group consensus seeking, and autonomous multi-agent negotiation. The interdependent principles are justified, and the methodological solutions underlying their implementation are provided.

Energy cost is the main constraint in modern wireless communication system. A powerful scheme due to optimal energy cost is provided for a single node server in this paper. In wireless communications, the total energy for transmitting packets can be reduced by proper regulating the service rate due to different packet sizes. In our study, a generic method applying the Lagrange Multiplier methods for optimizations is proposed. We show the energy cost is a convex function and it is easy to achieve the optimization. Our contribution focused on minimizing the total energy cost induced by the transmission energy in a single server with multi-queues. The methodology presented in this paper can effectively save the energy cost due to energy consumption in wireless communication systems.

In this paper the immune network system was presented by the sequence of species with new immunological components allowing more plausible to reflect the immune response processes. The mathematical model oriented to the describing of the more realistic immune processes in the dynamics allowed to organize the computational experiment in the first to demonstrate a possible very complex behavior including chaotic regimes. The results of modeling of dynamic immunological processes with chaotic behavior are represented and considered.

A possibility to use the formant features (FF) in the user-dependent isolated word recognition has been investigated. The word recognition was performed using a dynamic time-warping technique. Several methods of the formant feature extraction were compared and a method based on the singular prediction polynomials has been proposed for the recognition of isolated words. Recognition performance of the proposed method was compared to that of the linear prediction coding (LPC) and LPC-derived cepstral features (LPCC). In total, 111 Lithuanian words were used in the recognition experiment. The recognition performance was evaluated at various noise levels. The experiments have shown that the formant features calculated from the singular prediction polynomials are more reliable than the LPC and LPCC features at all noise levels.

This paper presents the Croatian context-dependent acoustic modelling used in speech recognition and in speech synthesis. The proposed acoustic model is based on context-dependent triphone hidden Markov models and Croatian phonetic rules. For speech recognition and speech synthesis system modelling and testing the Croatian speech corpus VEPRAD was used. The experiments have shown that Croatian speech corpus, Croatian phonetic rules and hidden Markov models as the modelling formalism can be used to develop speech recognition and speech synthesis systems in parallel for a highly flective and free order language like Croatian. We propose an evaluation procedure for speech synthesis, which combines an objective and a subjective evaluation approach and we present the achieved evaluation results. The proposed procedures for Croatian acoustic modelling were developed as parts of speech interfaces in a spoken dialog system for a limited weather forecast domain.

In this paper a detail analysis of speech coding algorithm based on forward adaptive technique is carried out. We consider an algorithm that works on frame-by-frame basis, where a frame consists of a certain number of speech samples. Buffering frame-by-frame an estimation of the gain defined as squared root of the frame variance is enabled. The information about the gain (side information) and the code book of a nonadaptive quantizer, which is designed for the unit variance case of the input signal, are further used when designing an adaptive quantizer. In such a way better quantizer adaptation to the varying input statistics is provided. Observe that the goal of this paper is to investigate the preference that for the wide range of variance change could be achieved when implementing in the forward adaptive speech coding algorithm, the recently developed effective method for the Lloyd–Max's algorithm initialization, which provides optimal Lloyd–Max's quantizer performances for the unit variance case of the input signal. We destine to consider the speech coding algorithm based on forward adaptive technique since the backward adaptation provides SQNR (signal to quantization noise ratio) within 1 dB of the forward adaptation. We provide theoretical and experimental results (performances of our algorithm) which are compared with the optimal results. Additionally, we discuss the performances of speech coding schemes designed according to G. 711 standard and we point out the benefits that can be achieved by using our algorithm. Finally, in order to find better solution for implementation of the proposed algorithm in practice we consider the performances of our algorithm when log-uniform as well as uniform scalar quantizer are used for gain quantizing.

Classification and regression tree approach was used in this research to model phone duration of Lithuanian. 300 thousand samples of vowels and 400 thousand samples of consonants extracted from VDU-AB20 corpus were used in experimental part of research. Set of 15 parameters characterizing phone and its context were selected for duration prediction. The most significant of them were: identifier (ID) of phone being predicted, adjacent phones IDs and number of phones in syllable. Models were built using two different data sets: one speaker and 20 speakers. The influence of cost complexity pruning and different values of pre pruning were investigated. Prediction by average leaf duration vs. prediction by median leaf duration was also compared. Investigation of most vivid errors was performed, speech rate normalization and trivial noise reduction were applied and influence on models evaluation parameters discussed. The achieved results, correlation 0.8 and 0.75 respectively for vowels and consonants, and RMSE of ~18 ms are comparable with those reported for Check, Hindi and Telugu, Korean.

With rapid growth of mobile wireless networks, handheld devices are popularly used by people and many mobile applications have been rapidly developed. Considering the limited computing capability of smart cards or mobile devices, the security scheme design suitable for these mobile devices is a nontrivial challenge. A user authentication scheme is a mechanism to authenticate a remote user over an open network. In 2006, Das et al. proposed an identity (ID)-based remote user authentication scheme with smart cards using bilinear pairings. Unfortunately, their scheme is insecure against forgery attack. Recently, Giri and Srivastava proposed an improved scheme to overcome the forgery attack. The computational cost required by the Giri–Srivastava scheme is expensive, especially for smart cards with limited computing capability. In addition, the Giri–Srivastava scheme is unable to be used for a multi-server environment. This paper presents an efficient and secure ID-based remote user authentication scheme using bilinear pairings. Based on the computational Diffie–Hellman assumption, we show that the proposed scheme is secure against existential forgery on adaptively chosen-message and ID attack in the random oracle model. As compared with the recently proposed pairing-based authentication schemes, our scheme has better performance in term of the computational cost and it is suitable for a multi-server environment in distributed networks. Performance analysis and experimental data of related pairing operations on smartcards are given to demonstrate that our scheme is well suited for mobile devices with limited computing capability.

Multi-criteria decision making is used in many areas of human activities. Each alternative in multi-criteria decision making problem can be described by a set of criteria. Criteria can be qualitative and quantitative. They usually have different units of measurement and different optimization direction. The normalization aims at obtaining comparable scales of criteria values. The normalization of criteria values is not always needed, but it may be essential. In the new program LEVI 3.1 the following normalization methods are possible: vector, linear scale, non-linear and new logarithmic techniques. Logarithmic normalization has never been used before. The present research is focused on introducing a new logarithmic method for decision making matrix normalization.