Uzhhorod National University

About: Uzhhorod National University is a education organization based out in Uzhhorod, Ukraine. It is known for research contribution in the topics: Raman spectroscopy & Laser. The organization has 1089 authors who have published 1056 publications receiving 5187 citations. The organization is also known as: State Higher Education Establishment "Uzhhorod National University" & Uzhhorod State University.

Limited method for the case of algorithmic classification tree

Abstract: Context. The general problem of constructing the algorithmic recognition (classification) trees on the basis of a limited method in the artificial intelligence theory has been considered. The object of the present study is a concept of classification tree (a limited method-based algorithmic classification tree). The relevant methods, algorithms and schemes (a limited method) of constructing the algorithmic classification trees are the subject of this study. Objective. The goal of this work is to develop a simple and efficient limited method of constructing the tree-like recognition and classification models on the basis of the algorithmic classification trees for training selection of a large-volume discrete information that is characterized by a structure of classification trees obtained from independent recognition algorithms assessed in accordance with their general efficiency calculation functional for a wide class of applied tasks. Method. A limited method of constructing the algorithmic classification tree is suggested that constructs a tree-like structure for the preset initial training selection (an ACT model) consisting of a set of autonomous classification/recognition algorithms assessed at each ACT construction step (stage) in accordance with the initial classification. In other words, the limited method of constructing the algorithmic classification tree is suggested, and its idea is a step-by-step approximation of the arbitrary volume/structure selection by a set of independent classification/recognition algorithms. This method provides formation of a current algorithmic tree vertex (node, the generalized ACT attribute) with the selection of the most efficient (high-quality) autonomous classification algorithms from the initial set and construction completion of only those ACT structure paths, where the largest number of classification errors occurs. Such approach at constructing the resultant classification tree (the ACT model) allows the tree size and complexity (i.e. the total number of transitions, structure vertices and layers) to be reduced considerably, the quality of the next analysis (interpretability) and the possibility of decomposition to be increased as well as the ACT structures to be built given the limited hardware resources. The above limited method of constructing the algorithmic classification tree enables one to construct diverse tree-like recognition models with a preset accuracy for a wide class of the artificial intelligence theory tasks. Results. The limited method of constructing the algorithmic classification tree developed and presented in this work has software realization and was investigated and compared to the logical classification tree methods (on the basis of elementary attribute set selection) and the algorithmic tree classification methods (first and second-type ones) when solving the task of real geological data recognition. Conclusions. The experiments carried out in the present work have proved the performance capabilities of the software suggested and demonstrate the possibility of its promising utilization for the solution of a wide spectrum of applied recognition/classification problems. The outlook of further studies and approbations may be related to the creation of methods of other-type algorithmic classification trees that introduce a stopping criterion for the procedure of a tree model in accordance with the structure depth, optimization of its software realizations and to the experimental studies of this method for a wider circle of practical tasks.

Electrical Conductivity of Ceramics Based on (Cu 1-x Ag x ) 7 Si S 5 I Nanocrystalline Powders

Abstract: Ceramic samples based on $(c_{u1-x}Ag_{x})_{7}SiS_{5}I$ nanocrystalline powders were manufactured by pressing them at $\sim 400$ MPa pressure and subsequent annealing at 973 K during 36 hours. Investigations of electrical conductivity of ceramics based on $(c_{u1-x}Ag_{x})_{7}SiS_{5}I$ solid solutions were carried out by the method of impedance spectroscopy in the frequency range from 10 Hz to $2\times 10^{6}$ Hz and in the temperature range 292-383 K. It is established that with increasing the content of silver atoms in ceramic samples based on $(c_{u1-x}Ag_{x})_{7}SiS_{5}I$, the ionic component of electrical conductivity increases nonlinearly, while electronic component decreases nonlinearly, and their ratio increases nonlinearly and for $Ag_{7}SiS_{5}I$ exceeds 60000.

Influence of X-Ray Irradiation on Energy Pseudogap and Refractive Index of (Ga 0.1 In 0.9 ) 2 Se 3 Films

Abstract: Thermal evaporation technique was used to deposite $\gamma_{1}$ films. As-deposited thin films were irradiated by means of wideband radiation of Cu-anode X-ray tube at different exposition times. Spectral ellipsometry measurements were conducted in order to obtain refractive index and extinction coefficient dispersions. Optical transmission spectra of X-ray irradiated $(\text{Ga}_{X}\text{In}_{1\rightarrow x})_{2}\text{Se}_{3}$ films were measured depending on irradiation time. Parameters of Urbach absorption edge for X-ray irradiated $(\mathbf{Ga}_{0.1}\mathbf{In}_{0.9})_{2}\mathbf{Se}_{3}$ films were studied. The investigation revealed the nonlinear decrease of energy pseudogap together with nonlinear increase of Urbach energy and refractive index, as well as the increase of X-ray irradiation time.

Quantitative indicators of microcirculation of the skin of the lower extremities

Abstract: Abstract Purpose of the study. To study the quantitative indicators of microcirculation and perfusion of the skin of the lower extremities, taking into account the angiosomal theory. Materials and methods. We studied the microcirculation of the skin of the lower extremities in 31 people, taking into account the angiosomal approach without pathology of the cardiovascular system on the device Easy-LDI company AIMAGO SA (Switzerland). Results. We found that the highest rates of perfusion units on the thigh were found in the pool of the sciatic and posterior arteries, the lowest – in the pool of the deep femoral artery and popliteal artery. On the shin, the highest rates of microcirculation are found in the pool of the posterior tibial artery, the lowest – on the foot. Having such an objective quantitative perfusion index, it is easy to determine the occlusion of the arteries corresponding to the angiosomes, areas of the skin of the lower extremity and to quantify the results of the treatment. Conclusions. The developed indicators of skin perfusion of angiosomes of the lower extremities can normally form the basis for diagnosing the degree of stenosis of the main arteries, serve as an indication for direct and indirect methods of revascularization in obliterating diseases of the arteries of the lower extremities and quantify immediate and long-term treatment. Keywords: Angiosomal theory, transcutaneous oxygen tension, regional perfusion index, skin microcirculation, revascularization