Communications - Scientific Letters of the University of Zilina, 2003 (vol. 5), issue 2
Articles
Acoustoelectric Investigation of Deep Centers in Bulk and Multilayered Semiconductors
Peter Bury, Igor Jamnicky, Peter Hockicko
Communications - Scientific Letters of the University of Zilina 2003, 5(2):5-13 | DOI: 10.26552/com.C.2003.2.5-13 
Two basic versions of the acoustic deep-level transient spectroscopy (A-DLTS) technique based on the acoustoelectric effect resulting from the interaction between an acoustic wave and interfaces have been used to study deep centers in semiconductor structures. The former uses the high frequency transverse acoustoelectric signal (TAS) arising from the interaction of surface acoustic wave electric field and free carriers at the structure interfaces. The latter uses an acoustoelectric response signal (ARS) produced by the structure interface when a longitudinal acoustic wave propagates through the structure. An additional version of A-DLTS uses the acoustoelectric...
To the Influence of Material Dispersion on the Intermodal Interference in Optical Fibres
Ivan Turek, Daniel Kacik, Ivan Martincek
Communications - Scientific Letters of the University of Zilina 2003, 5(2):14-17 | DOI: 10.26552/com.C.2003.2.14-17
The comparison of computed and measured spectral dependence of intermodal interference in step-index optical fibre presented in this paper shows the influence of material dispersion on the intermodal interference in optical fibres. It is shown that the influence of material dispersion on intermodal interference is high enough to allow determination of the material dispersion difference of core and cladding of optical fibres.
Molecular Ultrathin Layers and Ordered Systems
Drahoslav Barancok, Julius Cirak, Pavol Tomcik, Marek Vanco
Communications - Scientific Letters of the University of Zilina 2003, 5(2):18-21 | DOI: 10.26552/com.C.2003.2.18-21
Monomolecular assemblies on substrates, now termed Langmuir-Blodgett (LB) films, exhibit many interesting properties and can perform functions which give them perspectives to impact advanced technologies and molecular electronics in an important way. In this article we briefly present our recent efforts aimed at the study of nanoelectric phenomena in the Langmuir monolayer formed on a water surface as well as electrochemical properties of Langmuir-Blodgett films deposited on the surface of an ultramicroelectrode involved in microsensors.
The Study of Kinetic Colloidal Particles in Magnetic Fluids using Diffraction Effect on an Optical Grating Created by Intersecting Laser Beams
Julius Stelina, Ctibor Musil
Communications - Scientific Letters of the University of Zilina 2003, 5(2):22-25 | DOI: 10.26552/com.C.2003.2.22-25
In this paper a short characteristic of magnetic fluids and some of their applications are presented a simple one-dimensional model of creation of thermal and absorption grating is explained. The method of generation of optical grating by using the interference two intersecting coherent laser beams is presented. In conclusion some possibilities of utilisation optical created grating are also indicated.
Investigation of Local Mechanical Properties of Al-Cu-Li Alloys by Acoustic Microscope
Sofia Berezina, Oleg Kolosov, Juraj Slabeycius
Communications - Scientific Letters of the University of Zilina 2003, 5(2):26-28 | DOI: 10.26552/com.C.2003.2.26-28
The reflected scanning acoustic microscope was used for investigation of elastic properties of extruded Al-Cu-Li alloys. The local sound velocity and attenuation were measured by the V(z) curve method. The results show strong anisotropy of material due to extrusion of the sample.
Semiconductor Lasers Based on Quantum Well Structures
Dusan Pudis, J. Kovac, Jr., J. Kovac, J. Jakabovic
Communications - Scientific Letters of the University of Zilina 2003, 5(2):29-32 | DOI: 10.26552/com.C.2003.2.29-32
We present electrical and optical properties of the quantum well laser structures based on InAs / AlxGa1-x As material systems. The experimental results obtained from room- and low temperature electroluminescence measurements of InAs/Al0.40Ga0.60 As revealed the excellent emission spectra in the visible range 620-660 nm. The experimentally obtained transitions energies were compared with simple Kronig-Penney simulations. Going to low temperatures the stimulated emission from the cleaved edge was observed, which could be real perspective for laser applications.
Interaction of Electromagnetic and in Conductors and its Utilization
Ivo Cap, Klara Capova, Dagmar Faktorova
Communications - Scientific Letters of the University of Zilina 2003, 5(2):33-36 | DOI: 10.26552/com.C.2003.2.33-36
The paper deals with the interaction of electromagnetic and acoustic processes in a conducting medium in presence of an external magnetic field. The electromagnetic excitation of acoustic wave similarly as acoustic excitation of electromagnetic wave is described. The practical utilization consisting in contactless acoustic wave generation and detection is demonstrated.
X-Ray Diffraction Line Profile Analysis of Strongly Textured Thin Films of ZnO
P. Sutta, Q. Jackuliak
Communications - Scientific Letters of the University of Zilina 2003, 5(2):37-40 | DOI: 10.26552/com.C.2003.2.37-40
ZnO thin films have been deposited on SiO2 -Si and Al-SiO2 -Si substrates by reactive sputtering. X-ray diffractometry was used to determine microstructural disorder parameters in ZnO thin films with strong preferred c-axis orientation. The influence of Al and Al2O3 buffer layer on preferred c-axis orientation and microstrain of crystallites was also studied. The microstrains and domain size showed only a small dependence on the preference of a buffer layer, but they depend on the thickness of ZnO thin film. The stress gradient along the c-axis was observed in all of studied samples.
Ultrasonic Investigation of Plastically Deformed Steel-Contribution to Analysis of Degradation Influence
Peter Bury, S. Barta, V. Magula, V. Slugen, T. Smida
Communications - Scientific Letters of the University of Zilina 2003, 5(2):41-43 | DOI: 10.26552/com.C.2003.2.41-43
Study of degradation influence on material properties of some steel components is very important because of their serviceable life. One of the most important side of the degradation process considering operation conditions is cumulated plastic deformation. The ultrasonic investigation of materials through the ultrasound attenuation and velocity measurements have been proved an effective tool of the study of structural changes caused also by plastic deformation due to the degradation process. In the contribution we present the results of both the frequency dependence of ultrasound attenuation and velocity measurements of steel samples (38ChN3MFA) with...
A Design of an Induction Method Device with Respect to the Signal and Noise Sensitivity
Dalibor Blazek, Jozef Kudelcik, Jozef Blazek
Communications - Scientific Letters of the University of Zilina 2003, 5(2):44-47 | DOI: 10.26552/com.C.2003.2.44-47
An objective of this article is the relationship between the signal sensitivity, the noise sensitivity and the distribution of turns of winding on any chosen axis-symmetric core.The analytical study originates from Faraday induction law and Nyquist theorem. Different windings were compared with respect to their physical properties.
Dynamic Response of a Trunk Structure Building to Multiple Transient Loadings
Tadeusz Kasprowicz, Leopold Kruszka, Ryszard Rekucki
Communications - Scientific Letters of the University of Zilina 2003, 5(2):48-53 | DOI: 10.26552/com.C.2003.2.48-53
The paper provides information concerning the dynamic response of building structures exposed to paraseismic loadings. Dynamic loadings can arise inside buildings or can be transmitted to buildings through subsoil, causing vibrations of structures. To carry out a dynamic diagnostics of existing buildings, it is necessary to take measurements of vibration parameters directly from the investigated structure. The paper presents some examples of such investigations, as well as a comparison of the obtained results and calculations with standard dynamic characteristics of existing buildings.
Internal Forces Tests in Retaining Walls of Road Embankments
Andrzej Surowiecki, Edward Hutnik
Communications - Scientific Letters of the University of Zilina 2003, 5(2):54-58 | DOI: 10.26552/com.C.2003.2.54-58
The subjects of this paper are resistance structures constituted by reinforced soil applied in highway engineering. Test results carried out on laboratory models are presented, leading to the estimation of the size and shape of the wedge of the reinforced soil embankment block, in the boundary state of active pressure. The task was conducted in the following two stages: on the basis of measured horizontal strains of the embankment (unitary lateral pressures) and reinforcing dowels - with the application of sensors of electro-resistant tensometry. The slip curve, determining the searched block wedge, is formed by the points of maximal normal stress...