- TITLE:
SYNTHESIS AND STUDY OF THE CURRENTS OF ELECTRO DRIVE SYSTEM WITH SINGLE TREE PHASE CYCLOCONVERTER
- AUTHOR(S):
C. Petkov
- ABSTRACT:
The paper presents a way of theoretical synthesis and study about electrical drive system with induction motor and direct frequency converter. The result of the synthesis is nonsinosoidal form of the phase currents for different frequencies. The representative vector of the stator current is found and important conclusions are made. The form of the stator,s current allows a spectral analysis on the Fourier transform, which is an important part of the engineering studies.
- TITLE:
MODELING AND ANALISYS OF INDUCTOR BY VOLUME HEATING WITH DIFFERENTIATED THERMAL ZONES IN LENGTH
- AUTHOR(S):
M. V. Simeonov, H. T. Ibrishimov
- ABSTRACT:
In this paper thermal fields that arise in an inductor in the process of volume heating are studied. The equations have been solved by means of the finite elements method, taking into account the characteristic non-linearity of the used material. The analysis was broadened with process modeling by means of COMSOL Multiphysics 4.3.а. The obtained results confirm the reliability of the developed methods com-pared to the manufacturing and power parameters for the given supply source in regard to power, current and frequency of the practical example.
- TITLE:
SYSTEM FOR AIR PARAMETER CONTROL
- AUTHOR(S):
G. Dimchev
- ABSTRACT:
The control of gas pollution is of utmost importance to environment protection and to ensuring healthy and safe working conditions. Modern development of industry, farming, transport is related to increasing the volume of emissions released in air and hence to the necessity of developing suitable technologies, equipment and filtering facilities for decreasing the emission of harmful substances and gases in the atmosphere. Air monitoring is also of great importance in order to prevent gas pollution which can spread over large territories for a short time. The present paper presents a system for control of gas pollution with: carbon dioxide, carbonic oxide, smoke, hydrogen, ammonia, nitric dioxide, ozone, hydrogen sulphide, methane, ethanol, hydrogen and volatile organic compositions (VOCs), as well as measurement of temperature and relative humidity. The system employs ZigBee technology and the user’s interface allows monitoring of the above-listed gas pollutants and also alarm functions when the respective norms have been exceeded.
- TITLE:
GAS RECOGNITION BASED ON ARTIFICIAL NEURON NETWORKS
- AUTHOR(S):
Z. Nenova, G. Dimchev
- ABSTRACT:
Measuring air parameters is a task of paramount importance associated with protection of environment and human health as well as with providing safe and healthy working conditions. Monitoring of outdoor and indoor air quality often requires gas recognition and measuring gas concentration. This paper proposes a method of gas recognition with compensation of temperature and humidity impact and determining gas concentration based on artificial neuron networks. The method has been implemented by employing metal oxide gas sensors. The effectiveness of its application has been shown for enhancing the reliability of control and accuracy of measurement by compensating the impact of temperature and humidity of environment.
- TITLE:
FINITE ELEMENT SIMULATIONS OF A NEW METHOD TO THE FATIGUE LIFE ENHANCEMENT OF STRUCTURAL ELEMENTS WITH NONCIRCULAR OPENINGS
- AUTHOR(S):
G. V. Duncheva, M. D. Ivanova
- ABSTRACT:
The paper presents the outcomes from finite element simulations of a new method to enhancement of fatigue life of metal structural elements with noncircular openings. The method fulfils a process of “pure radial cold expansion” by means of a new patented tool. The study has been grounded on 3D finite element model of the process contains consecutively cold expansion of the preliminarily drilled two holes which correspond to the zones with fillets and next cutting the noncircular opening contour. On the basis of the finite element results it has been proved that the created compressive field around the fillet is symmetric in relation to the middle plane of the plate, i.e. the new method ensures the minimal axial gradient of the residual circumferential normal stresses. In conclusion, it have been determined the rational level of the degree of cold expansion – DCE=4%
