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SEKCE 1 - ABSTRAKTY
APPLICATIONS COMPUTER EQUIPMENT AT OPTICAL MEASUREMENTS OF PNEUMATIC TYRES GROWTH DURING FREE ROTATION
L. Bartoněk1, J.
Keprt2
1Natural
Science Faculty of Palacky University, Šmeralova
10, 772 07 Olomouc, Czech Republic, e-mail: barton@risc.upol.cz; phone
068/5634291, fax 5224047,
2Joint Laboratory of Optics of Palacky
University and Institute of Physics of Academy of Science of Czech Republic, Šmeralova 10, 772 07 Olomouc, Czech Republic,
e-mail keprt@prfoptnw.upol.cz; phone
068/5631507, fax 5224047
Abstract
The presented method is based on utilization of optical trace of luminous slot on tyre profile. This optical trace enables the measurement of tyres growth at free rotation during low and high revolution. It is one of tests in sense of regulation of U.N Committee for homologation of motorcycle tyres.
NEW
ACOUSTIC TECHNIQUES FOR DEEP CENTERS INVESTIGATION IN BULK AND MULTILAYERED
SEMICONDUCTORS
Žilinská
univerzita v Žiline
Elektrotechnická
fakulta
e-mail: bury@fel.utc.sk
Abstract
Principles of the new acoustic spectroscopy technique A-DLTS and the new method based on the investigation of the acoustic wave generation is presented.
MAGNETOMETRIC MEASUREMENT OF STEEL STRUCTURES UNDER COMPRESSIVE STRESS
Čermáková Eleonora
Faculty of Civil Engineering
Dp. of Physics
Zizkova 17, 60200 Brno,
Czech Republic
tel: 00420 5 41147662, Fax:
00420 5 41147666
E- mail: cermakova.e@fce.vutbr.cz
Abstract
The state of steel structures under compressive stress can be studied with a sensitive magnetometer. The variation of magnetic induction due to changes in mechanical stress is brought about by physical phenomenon called the inverse magnetostriction. The change in magnetic induction was detected by the VEMA 030 magnetometer.
INVERSE MAGNETOSTRICTION DETECTED ON STEEL STRUCTURES UNDER HEAT STRESS
Eleonora Cermakova,
Viktor Nohal, Stanislav Vesely
Faculty of Civil Engineering
Dp. of Physics
Zizkova 17, 60200 Brno,
Czech Republic
tel: 00420 5 41147662, Fax:
00420 5 41147666
E- mail: cermakova.e@fce.vutbr.cz
Abstract
Steel structures become magnetized in the natural geomagnetic field. They display their magnetic properties through certain sizes of the magnetic induction vector. The varying temperature of the steel structures due to meteorological factors entails changes in magnetic induction as a result of the varying stress developed in the structure.
On the Choice of the Optimum Tilt Of Photovoltaic Arrays
Hamdy K. Elminir, Vítězslav
Benda and Ivan Kudláček
Abstract
This paper seeks to furnish a fundamental piece of information to the solar engineer or scientist regarding the proper choice of solar collector’s tilt angle in the field of design and construction a PV system for electric power generation at the Prague surrounding area.
Experimental verification of the result obtained for the optimum angle of tilt for different orientation PV panel was carried out during several months of the year. The tests were started, when the PV panel is vertical and facing north, the test continues to the horizontal mode, and completed to south facing with tilt angle + 90°. Every ten degrees variation in the tilt angle, the panel parameters (current, voltage, and electrical output power) was recorded, the same procedure for East–West orientation. The results reveal that changing the tilt angle 12 times in a year (i.e., using the monthly averaged optimum tilt angle) maintains approximately the total amount of solar radiation near the maximum value that is found by changing the tilt angle daily to its optimum value.
NOISE RELIABILITY INDICATORS FOR PN JUNCTION DEVICES
Pavel Hruška
Department of
Physics
E-mail: hruskap@dphys.fee.vutbr.cz
Abstract
A non-destructive method of reliability prediction for PN junction microelectronic devices is described, including reliability indicators, which are based on the devices’ low frequency noise characteristics. Experimental results illustrate applicability of this method.
CAPACITANCE-VOLTAGE ANALYSIS FOR SILICON SOLAR CELLS
Ali Ibrahim and Zdeněk Chobola
Brno
University of Technology, Faculty of
Civil Engineering
Zizkova 17, 602
00 Brno, Czech Republic
E-Mail: chobola@dp.fce.vutbr.cz
Abstract
Studies of capacitance associated the depletion region of a Schottky barrier or an abrupt junction provide extensive information on the concentrations and characteristics of electrically active centres in epitaxial layers and the near surface region of bulk semiconductors. Analysis of the variation of capacitance with applied voltage is the basis of several techniques for determination of the net doping density and its depth profile. The analysis of C-V method for monocrystalline silicon solar cells (n+pp++ PESC) of area 100 cm2 constructed by p-type (CZ) silicon wafer is discussed in this paper.
PERMEABILITY OF CONCRETE
Vlasta Juránková, Jiří Adámek,
Ondra Michalko
Brno University
of Technology
Faculty of
Civil Engineering
Department of
Physic
602 00 Brno,
Žižkova 17
e-mail: jurankova.v@fce.vutbr.cz
Department of
Building Materials and Testing Methods
602 00 Brno, Údolní 53
e-mail: adamek.j@fce.vutbr.cz
Czech Technical
University in Prague
Faculty of
Civil Engineering Department of Physic
166 29 Praha, Thákurova 7
e-mail: michalko@fsv.cvut.cz
Abstract
The properties of most silicate base produced construction materials depend to a large extent on their porosity and, at the same time, on the actual gas pocket filling with water or water vapours. The quality of a construction material used in a particular structure is subject to degradation in the course of its long-time utilizitation. One of objective methods allowing to quantify the instantaneous status of the porous structure of building elements is the surface layer air and water permeability determination method. They are a new, non-destructive method, applicable both in the laboratory and on a construction site.
ELECTROMAGNETIC EMISSION SIGNAL GENERATED BY CRACK CREATION
P. Koktavý, B. Koktavý and J.
Šikula
Brno University of Technology
Faculty of Electrical Engineering and Computer Science
Physics Department
Phone: 00-420-5-4114 3394, Fax: 00-420-5-4114 3133
E-mail: koktavy@dphys.fee.vutbr.cz
Abstract
When a stress is applied to the solids (rocks or tiles) cracks creation can be detected by signals of an acoustic and electromagnetic emission. The recorded electric signal is superposition of crack walls “self” vibration and vibration due to an ultrasonic wave. The simultaneous investigation of acoustic and electromagnetic emission signals enable us to localise the crack position in solids.
ASSESSING DAMAGE IN CORRODED FERROCONCRETE USING ACOUSTIC EMISSION
Jan Martinek, Zdeněk Chobola
Department of Physics
Žižkova 17, 602 00 Brno, Czech Republic
e-mail:honza@dp.fce.vutbr.cz
Abstract
One of the methods to determine degree of metal corrosion in concrete is the analysis of acoustic emission (AE) characteristics. The acoustic emission behaviour of reinforced concrete beams can be investigated to characterize and identify different sources of damage icluding microcrack development localized crack propagation and debonding of the reinforcing steel.
BURST NOISE IN THIN AMORPHOUS FILMS
Jan Pavelka
Czech Noise Research Laboratory, Brno University of Technology,
Faculty of Electrical Engineering, Department of Physics
Tel/Fax: +4205 4114 3398, e-mail: pavelkaj@dphys.fee.vutbr.cz
Abstrakt
A low frequency noise and charge carriers transport mechanism analysis have been performed on Ta - Ta2O5 - MnO2 heterostructures of various thickness to determine the current noise sources. The model of MIS structure can be used to give physical interpretation of VA characteristic both in normal and reverse modes. Correlation between leakage current and noise spectral density was evaluated.
Rebar Corrosion in Concrete Bridges and its Detection by Acoustic Emission Method
Josef Stryk, Karel Pospíšil
CDV – Transport
Research Centre
Road
Department
Líšeňská 33a,
636 00 Brno, Czech Republic
Phone: +420 5
48423726, Facsimile: +420 5 48423712
e-mail: pospisil@cdv.cz
Abstrakt
In a lot of world countries road administrators have to face to bad technical condition of bridges. The situation is cased by the lack of financial resources for bridge maintenance but also by absence of reliable fast and cheap monitoring method that would be able to find out the bridge defects in early stage. Finding of this method should head to simple and cheap maintenance way. Method based on acoustic emission (AE) principle appears to be very suitable because AE is changed during developing processes as concrete cracks and rebar corrosion are.
NOISE SPECTROSCOPY OF THICK FILM RESISTORS
Vlasta Sedláková
Czech Noise Research Laboratory, Brno University of Technology,
Faculty of Electrical Engineering, Department of Physics
Tel/Fax: +4205 4114 3398, e-mail: sedlaka@dphys.fee.vutbr.cz
Abstract
The noise spectroscopy and non-linearity measurements of thick film layers are proposed as a diagnostic tool for prediction of possible types of failure. The characteristics measured using two resistor pastas were compared and resistor termination influence evaluated with contact noise found negligible. Correlation between long-term stability, current noise and third harmonic index was investigated.
Electromagnetic and Acoustic Emission in Solids
J. Sikula, V. Sedlakova, P.
Koktavy, J. Pavelka and J. Majzner
Department of Physics, Brno University of Technology, Czech Republic
Fax. +4205 4114 3398 E-mail: sikula@dphys.fee.vutbr.cz
Abstract
Electromagnetic (EME) and acoustic (AE) emission, which are generated in stressed solids, can be used to indicate cracks and defects position, dimension and their orientation. When a crack is created in a solid, the faces of the crack are charged due to loss of the chemical bounds. The faces of the crack make up an capacitor. The EME signal is given by a redistribution of electric charges. As an EME sensor two conducting plates are fitted to the specimen making the parallel plate capacitor. Electric voltage measured on parallel plate capacitor is time dependent due to vibration of crack walls. From the high frequency component, the crack length was estimated. Crack position was determined in experiment with four capacitor and four acoustic emission sensors
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Upraveno 1.11.2001 JiMa 15:55