Communications - Scientific Letters of the University of Zilina, 2014 (vol. 16), issue 1
Articles
Investigation of Interface States in Si/NAOS-SiO2/HfO2 Structures Using Complete Acoustic Spectroscopy
Peter Bury, Taketoshi Matsumoto, Stefan Hardon, Ivan Bellan, Marian Janek, Hikaru Kobayashi
Communications - Scientific Letters of the University of Zilina 2014, 16(1):3-9 | DOI: 10.26552/com.C.2014.1.3-9 
The set of MOS structures formed on n-type Si substrate with (NAOS)-SiO2/HfO2 gate dielectric layers was prepared and annealed in N2 atmosphere at various temperatures to stabilize the structure and to decrease the interface states density. Two Acoustic DLTS techniques using both surface (SAW) and longitudinal (LAW) acoustic waves including acoustoelectric response signal versus gate voltage dependence (Uac-Ug characteristics) were used to characterize the interface states and the role of annealing treatment. The main interface deep centers with activation energies about 0.30 and 0.20 eV, typical for dangling bonds were observed as well as a particular...
DLTS Study of InGaAsN/GaAs p-i-n Diode
Jakub Rybar, Lubica Stuchlikova, Ladislav Harmatha, Juraj Jakus, Jaroslav Kovac, Beata Sciana, Damian Radziewicz, Damian Pucicki, Wojciech Dawidowski, Marek Tlaczala
Communications - Scientific Letters of the University of Zilina 2014, 16(1):10-14 | DOI: 10.26552/com.C.2014.1.10-14
The paper presents an in-depth DLTS characterization of the p-i-n structure based on the InGaAsN/GaAs triple quantum well. Three DLTS evaluation methods were used for evaluation of the measured DLTS spectra. The results of all evaluation methods are compared and discussed. One of the evaluation methods that were used is a novel numerical algorithm that was recently developed. Several material and growth defects were identified. Emission from the quantum well was also observed and identified. The parameters of the energy levels were calculated and compared. The studied InGaAsN/GaAs structure is promising candidate for the solar cell applications and...
PDMS-Based Nanoimprint Lithography for Photonics
Dusan Pudis, Daniel Jandura, Peter Gaso, Lubos Suslik, Pavol Hronec, Ivan Martincek, Jaroslav Kovac, Sofia Berezina
Communications - Scientific Letters of the University of Zilina 2014, 16(1):15-20 | DOI: 10.26552/com.C.2014.1.15-20
Implementation of planar surface photonic crystal (PhC) structures leads to improvement of optical properties of optoelectronic devices. Application of such structures can be attractive for overall and local enhancement of light from patterned areas of the light emitting diode surface and for lightwave-guiding devices. We present techniques useful for PhC patterning and for patterning of different optic structures in surface of new promising material polydimethylsiloxane (PDMS). Paper proposes nanoimprint technology for fabrication of PhC in the surface of thin PDMS membranes for possible application in light emitting diodes. By PDMS patterning and...
NSOM Lithography for Organized Growth of Gap Nanowires
Ivana Lettrichova, Dusan Pudis, Agata Laurencikova, Stanislav Hasenohrl, Jozef Novak, Jaroslava Skriniarova
Communications - Scientific Letters of the University of Zilina 2014, 16(1):21-25 | DOI: 10.26552/com.C.2014.1.21-25
In this contribution, near field scanning optical microscope (NSOM) lithography is presented as a tool for organized growth of nanowires. Non contact mode of NSOM lithography was used to pattern planar structures in photoresist deposited on GaP substrate. In combination with lift-off technique, metal-catalyst particles on GaP substrate for subsequent growth of GaP nanowires were prepared. Different periodic and predefined arrangements of GaP nanowires were achieved.
Magnetosomes - Bacterial Magnetic Nanoparticles
Matus Molcan, Anezka Hashim, Jozef Kovac, Hubert Gojzewski, Andrzej Skumiel, Francois Royer, Damien Jamon, Peter Kopcansky, Milan Timko
Communications - Scientific Letters of the University of Zilina 2014, 16(1):26-32 | DOI: 10.26552/com.C.2014.1.26-32
The magnetic properties, magneto-optical effects and hyperthermia effect were studied in solution of magnetosomes extracted from cultivated bacteria Magnetospirillum sp. AMB-1. The properties of magnetosomes were changed using different conditions during synthesis and by modification of particles after synthesis by using sonication and ultracentrifugation methods. It was shown that adding a higher amount of Wolfe's vitamin solution (WVS) or ferric quinate (FQ) cause increase of the mean diameter from 47 nm (normal condition) up to 52 nm and 58 nm respectively. Hyperthermic measurements were performed for three types of magnetosome samples: (I) M -...
Temperature Effect on Anisotropy of Acoustic Attenuation in Magnetic Fluids Based on Transformer Oil
Jozef Kudelcik, Peter Bury, Peter Kopcansky, Milan Timko
Communications - Scientific Letters of the University of Zilina 2014, 16(1):33-38 | DOI: 10.26552/com.C.2014.1.33-38
Magnetic nanoparticles in magnetic fluids under the effect of magnetic field create structures, which are not arranged uniformly. These structures have various shapes dependent on the intensity and duration of applied magnetic field. In the case of such structures the anisotropy of acoustic attenuation can be observed. The effect of temperature on this process was studied by acoustic spectroscopy in transformer oil-based magnetic fluids. Taketomi theory that assumes existence of spherical clusters was used. These clusters form long chains, aligned in magnetic field direction. The cluster radius, the number density of the colloidal nanoparticles as...
Nano-Management of Linear Properties of Photonic Crystal Fibers
Daniel Kacik, Peter Tatar, David Liachovicky
Communications - Scientific Letters of the University of Zilina 2014, 16(1):39-44 | DOI: 10.26552/com.C.2014.1.39-44
The array of nanometer air holes positioned in the core can significantly modify the properties of guided mode in photonic crystal fiber. Changing geometrical properties of nanometer holes enables tuning of fiber dispersion and the effective mode area. This is related to losses of mode. In this paper, a rigorous analysis of dispersion and losses has been carried out for photonic crystal fiber with special arrangement of nanometer air holes in the core.
Investigation of Acoustic and Electrical Properties of a LIPO3 Metaphosphate Glass
Peter Hockicko, Peter Bury, Francisco Munoz, Laura Munoz-Senovilla
Communications - Scientific Letters of the University of Zilina 2014, 16(1):45-49 | DOI: 10.26552/com.C.2014.1.45-49
The acoustic attenuation spectroscopy in connection with conductivity and dielectric relaxation spectroscopy can be useful techniques for the study of relaxation processes and transport mechanisms in Li+ ion conducting glasses. A theoretical model and mathematical fit of acoustic and conductivity measurements are used for characterization of the ionic hopping motion, relaxation processes and transport mechanisms connected with the mobility of conducting Li+ ions. Results from acoustic measurements are compared with results obtained from electrical conductivity measurements.
Hiding the Vector Resonance Signal Hiding the Vector Resonance Signal
Mikulas Gintner, Josef Juran
Communications - Scientific Letters of the University of Zilina 2014, 16(1):50-54 | DOI: 10.26552/com.C.2014.1.50-54
We investigate how the interplay of the direct and mixing-induced couplings of the hypothetical SU(2)L+R vector triplet resonance to the third quark generation can hide the resonance signal in ,tb tb , and / bt tb channels. The vector resonances are assumed to represent bound states of hypothetical strongly-interacting new physics, the extension of the Standard model.
Temperature and Transverse Expansion of Fireballs in Pb+Pb Collisions at the LHC
Ivan Melo, Boris Tomasik
Communications - Scientific Letters of the University of Zilina 2014, 16(1):55-58 | DOI: 10.26552/com.C.2014.1.55-58
We analyze hadron transverse momentum spectra from Pb+Pb Collisions recorded by the LHC detector ALICE. As the theoretical model we use a Monte Carlo model which includes production and decays of resonances. The transverse expansion of the fireball is shown to be stronger and the freeze-out temperature higher than in similar collisions at RHIC, where collision energy is more than ten times lower.
The Selection of the dp Breakup Events from D CH2 Reaction at 500 MeV
Marian Janek, Beata Trpisova, Vladimir Petrovich Ladygin, Semen Mikhailovich Piyadin
Communications - Scientific Letters of the University of Zilina 2014, 16(1):59-63 | DOI: 10.26552/com.C.2014.1.59-63
The simulations of dC and dCH2 (CH2 - polyethylene) reactions for different detector configurations were performed at 500 MeV of deuteron energy. We present method by means of which the signal from dp breakup reaction can be separated from the background that mainly comes from the carbon content of the target.
Energy Efficient Speed and Position Control of Electric Drives with Pmsm
Jan Vittek, Branislav Ftorek
Communications - Scientific Letters of the University of Zilina 2014, 16(1):64-71 | DOI: 10.26552/com.C.2014.1.64-71
A new speed and position controller respecting principles of near-energy optimal control for the drives with permanent magnet synchronous motor are developed as a contribution to the energy saving and environmental protection. Two various approaches to the energy saving controller design are analysed. The first approach is strictly based on energy optimal control theory and derives analytical solutions of the control problem. The second approach develops approximated solution for the drive position controller when the optimal speed trajectory is modified to correspond to the triangular and trapezoidal profile. This approach enables not only to compare...
Qos Enhancement in Manet by Directional Power Control
Tomas Cakan, Vladimir Wieser, Andrej Tkac
Communications - Scientific Letters of the University of Zilina 2014, 16(1):72-77 | DOI: 10.26552/com.C.2014.1.72-77
In this paper, the 4-Way Directional Power Control with Recoil Loop (4WDPCRL) protocol for power control of directional antennas is presented. We propose the scheme with using of control packets (RTS/CTS/DATA/ACK) for exchanging information about node's transmitted energy. Whenever the frame is received, the appropriate power for transmitted frame is computed. This information is stored together with updated information about position of node to the table. If a new transmission occurs, the node sends packet with updated information about position and appropriate power. The simulation results show that the throughput and energy consumption of the proposed...
Influence of Surface Structure on Corrosion Behaviour of Welded Stainless Steel AISI 316l
Monika Halamova, Tatiana Liptakova, Ayman Alaskari, Fabio Bolzoni
Communications - Scientific Letters of the University of Zilina 2014, 16(1):78-83 | DOI: 10.26552/com.C.2014.1.78-83
The work deals with influence of surface structure on corrosion behaviour of austenitic stainless steel AISI 316L welded by TIG method without filler. Surfaces of the welded stainless steel were modified by mechanical treatment methods (grinding, garnet blasting, chemical method (pickling) and combination of both methods. Experimental procedures included the use of immersion and electrochemical tests where iron chloride (FeCl3) and sodium chloride (NaCl) solutions were used as test electrolytes. The surfaces of the specimens were examined using light microscopy and scanning electron microscopy (SEM). Experimental results confirmed the significant influence...
Throughput Estimation with Regard to Airtime Consumption Unfairness in Mixed Data Rate Wi-Fi Networks
Alaa Mohammed Abdul-Hadi, Olga Tarasyuk, Anatoliy Gorbenko, Vyacheslav Kharchenko, Thomas Hollstein
Communications - Scientific Letters of the University of Zilina 2014, 16(1):84-89 | DOI: 10.26552/com.C.2014.1.84-89
The paper discusses throughput unfairness inherent in the very nature of mixed data rate Wi-Fi networks employing random media access control technique CSMA/CA. This unfairness exhibits itself through the fact that slow clients consume more airtime to transfer a given amount of data, leaving less airtime for other clients. This decreases the overall network throughput and significantly degrades performance of high data rate clients. In the paper we propose mathematical models considering airtime unfairness and estimating wireless networks throughput depending on number of network connections and their data rates. These models show that all wireless...
Assessment of the Availability of an Offshore Installation by Stochastic Petri Net Modeling
Radim Bris
Communications - Scientific Letters of the University of Zilina 2014, 16(1):90-96 | DOI: 10.26552/com.C.2014.1.90-96
The purpose of this article is to illustrate the combination of stochastic Petri nets and Monte Carlo simulation approach for the evaluation of the production availability of a multi-state, multi-output offshore installation with operational loops. The presented test case comprises a great number of the problems encountered when dealing with probabilistic studies. The reason for using Petri net modeling is that it provides the necessary flexibility to describe the complexity of the plant and the realistic aspects of system behavior, such as a degradation and standby of components, maintenance, etc. Different production levels of the system are assessed...
Column Level Uni -Temporal Data
Michal Kvet, Karol Matiasko
Communications - Scientific Letters of the University of Zilina 2014, 16(1):97-104 | DOI: 10.26552/com.C.2014.1.97-104
The basic paradigm of conventional database systems is based on the current valid data processing. However, today's database systems should provide also management for historical and future valid data. Standard temporal model, using object level, stores the whole object data after the insert or update operation, although only some attributes changed their values. This paper deals with the principle of temporal data modelling based on the column level, not the whole object, describes the structure and principles of required methods, procedures, functions and triggers to provide functionality of the system. All designed and implemented solutions are...
Influence of Single Whole Body Vibration Training Unit on Kinematics of Human Gait in Children with Neurological Disorders
Jaroslav Majernik, Jozef Zivcak
Communications - Scientific Letters of the University of Zilina 2014, 16(1):105-108 | DOI: 10.26552/com.C.2014.1.105-108
Utilisation of Whole body vibration (WBV) has been considered as a beneficial and powerful method to improve mobility and physical status of the patients during past decade. Benefits that were already published include enhanced muscular strength, power or bone density. However, there were also no significant effects reported in several clinical studies. The main aim of this pilot study was to investigate immediate effects of single WBV training unit on quality of gait kinematics in children patients suffering from neurological disorders. Five children (4.10 ± 1.75 years, 1 male and 4 females) were assessed before WBV exposure (10 minutes, 2...
Multispectral Satellite Imagery Classification Using a Fuzzy Decision Tree
Sergey Stankevich, Vitaly Levashenko, Elena Zaitseva
Communications - Scientific Letters of the University of Zilina 2014, 16(1):109-113 | DOI: 10.26552/com.C.2014.1.109-113
A land cover classification system is very important nowadays for various remote sensing applications and many sectors of economy. Therefore, development of algorithms for multi- and hyperspectral imagery classification is an urgent task. In this paper we present a new efficient algorithm for multi- and hyperspectral imagery classification based on a fuzzy decision tree approach. Multispectral imagery spectral bands are used as fuzzy data source attributes and cumulative mutual information between them and the resulting fuzzy classification as a decision tree inducing criterion. The proposed algorithm ensures good classification accuracy.
Reliability Analysis of Noncoherent Systems by Logical Differential Calculus and Binary Decision Diagrams
Jozef Kostolny, Miroslav Kvassay, Stefan Kovalik
Communications - Scientific Letters of the University of Zilina 2014, 16(1):114-120 | DOI: 10.26552/com.C.2014.1.114-120
Reliability is the important characteristic of systems. Most of the systems consist of more than one component. Moreover, modern systems are very complex and they include a lot of components. Therefore, effective methods have to be developed for analysis of these systems. The techniques that have been already considered for this purpose are the Binary Decision Diagrams and the Logical Differential Calculus. However, these methods have been considered only for the coherent systems. In this paper, their use in the reliability analysis of the noncoherent systems is considered.
A Quality Estimation of Synthesized Speech Transmitted over IP Networks
Miroslava Mrvova, Peter Pocta
Communications - Scientific Letters of the University of Zilina 2014, 16(1):121-126 | DOI: 10.26552/com.C.2014.1.121-126
A design of the parametric models estimating a quality of synthesized speech transmitted through IP networks is presented in this paper. A Genetic Programming and Random Neural Network as machine learning techniques were deployed to design the models. A set of the quality-affecting parameters was used as an input to the designed parametric estimation models in order to estimate a quality of synthesized speech transmitted over IP networks (VoIP environment). The performance results obtained for the designed parametric estimation models have validated both genetic programming and random neural network as powerful techniques, delivering good accuracy...