Milko Yovchev - Academia.edu (original) (raw)
Papers by Milko Yovchev
2023 Eight Junior Conference on Lighting (Lighting)
2023 Eight Junior Conference on Lighting (Lighting)
2023 Eight Junior Conference on Lighting (Lighting)
ENVIRONMENT. TECHNOLOGIES. RESOURCES. Proceedings of the International Scientific and Practical Conference
The quality of the marked surfaces changes the optical characteristics. The aim of the study is t... more The quality of the marked surfaces changes the optical characteristics. The aim of the study is to optimize the contrast in laser marking of Steel 75. The influence of the step in the raster marking and the influence of the repetition frequency of the pulses on the reflection coefficient were analysed. The experimental investigations of the reflectance were carried out using a spectrophotometer. For the marked samples, it was found that when directing electromagnetic radiation with a wavelength in the studied range, there are areas with absorption and reflection of light. The reflectance is plotted as a function of marking step and laser frequency for the marked Steel 75 samples.
2022 Seventh Junior Conference on Lighting (Lighting)
В настоящата разработка се представят резултати от проект за модернизация на осветителна уредба в... more В настоящата разработка се представят резултати от проект за модернизация на осветителна уредба в учебна сграда в ТУ-Габрово с LED осветители. Извършено е обследване на съществуващото осветление в сградата, 3D моделиране на отделните помещения с отчитане на естественото осветление и вариантни светлотехнически изчисления с нови LED осветители. Приложени са резултати от изчисляване и оценка на енергийната ефективност на съществуващото и новото LED осветление, съгласно изискванията на стандарт БДС EN 15193:2009. Направена е технико-икономическа оценка на предлаганата модернизация на осветлението в сградата с LED осветители. / This paper presents some results of project for modernization of the lighting system in the academic building at the Technical University of Gabrovo with LED luminaires. Energy audit of existing lighting in the building, 3D modeling of individual rooms and variant lighting calculations including natural lighting with new LED lighting are carried out. Results from ...
The paper presents technical and economic data on the development of photovoltaic electricity in ... more The paper presents technical and economic data on the development of photovoltaic electricity in Bulgaria over the last 10 years. The mix of different types of conventional and renewable energy sources in the country's electricity system is shown. The changes in the installed photovoltaic capacities and the price of electricity generated by them for the studied period are shown in tabular and graphical form. The number of photovoltaic power plants and their distribution by groups of individual powers are given. Brief technical and economic data for some of the largest photovoltaic power plants in Bulgaria are provided. Data analysis shows a short period of rapid development of highcapacity photovoltaic power plants construction after the introduction of high feed-in tariff for the purchase of photovoltaic electricity, as well as the influence of the installed photovoltaic capacities on the market change of the feed-in tariff over time. Feed-in tariff cost decreases remarkably with the increase of the installed photovoltaic capacity and even shows removal tendency for larger-capacity photovoltaic power plants. Examples of the economic profitability of grid-connected and autonomous photovoltaic systems in Bulgaria are given. The analysis and conclusions of the paper could be useful in determining new government policies and setting new market conditions to promote the development of renewable energy sources in Bulgaria and other countries.
2018 Seventh Balkan Conference on Lighting (BalkanLight), 2018
The paper presents a results of software calculation and experimental measurement determination o... more The paper presents a results of software calculation and experimental measurement determination of unified glare rating (UGR) for two teacher rooms in an educational building. Three-dimensional computer modeling and multivariate UGR software calculation with light-emitting diode luminaires having different lighting distributions and taking into account the actual position and the line of sight of the observer are performed. A methodology for experimental measurement and determination of UGR has been proposed and demonstrated for the same two rooms. The results are presented in tabular and graphical form. A comparative analysis of the results obtained from the software calculations and the experimental determination of UGR is carried out. Conclusions have been made about the influence on the accuracy of the URG values obtained of the light distribution type of the luminaires, the location and orientation of the line of sight of the observer, and the choice of the background luminance surface.
Contemporary Materials, 2013
Photovoltaic power supply of street lighting has been developing rapidly in recent years. A stand... more Photovoltaic power supply of street lighting has been developing rapidly in recent years. A stand-alone photovoltaic (PV) system supplying light-emitting diode (LED) outdoor luminaires has been constructed in the Technical University of Gabrovo. A PV-LED system consists of a PV module, a storage battery, a solar controller, a LED lamp and a system for remote visualization of operating modes. Working processes for optimization of the night operating mode of LED luminaire have been studied. Data on electrical energy stored by the battery and consumed for lighting have been presented.
2019 Second Balkan Junior Conference on Lighting (Balkan Light Junior), 2019
A methodology for iterative optimization of optical systems for street LED luminaires intended fo... more A methodology for iterative optimization of optical systems for street LED luminaires intended for roads designed according to luminance requirement is proposed in the paper. The methodology comprises the following stages: iterative change of the shape of secondary lens of a computer model of the optical system, photometric analysis using the Monte Carlo raytracing method of the modelled three-dimensional optical systems to calculate their photometric characteristics, optimal road lighting calculations with an optimum criterion – maximum luminaire spacing meeting the requirements of standard for the selected M6 lighting class of the road, through the analysis of which the optimal solution is found.
2020 Fifth Junior Conference on Lighting (Lighting), 2020
Building and study of a three-dimensional model of an optical system of LED lamp for indoor light... more Building and study of a three-dimensional model of an optical system of LED lamp for indoor lighting and photometric analysis by using Monte Carlo raytracing method of the modelled optical system with a diffuser made of various transmissive materials, transmittance and scattering angle is done in this paper. The results for the calculated number of ray reaction, zonal luminous fluxes, beam angle, light distribution curves and efficiency of the LED lamp optical system for different materials of the modeled diffuser are presented. A conclusion in terms of the realized photometric indicators and achieved total efficiency of the LED lamp optical system with various diffuser materials is done.
2019 Second Balkan Junior Conference on Lighting (Balkan Light Junior), 2019
In the paper is proposed methodology for iterative three-dimensional computer modeling of seconda... more In the paper is proposed methodology for iterative three-dimensional computer modeling of secondary optical lenses for street LED luminaires by using of Photopia and AutoCAD software. The methodology allows achieving of various desired light distributions of the luminaires by iteratively modifying the three-dimensional shape of the secondary lens. The created three-dimensional models of optical lenses shown are tested by Monte Carlo raytracing photometric analysis. The results confirm the performance and the possibilities for application of the proposed methodology.
Results of the study of the change of electrical characteristics of light-emitting diode (LED) lu... more Results of the study of the change of electrical characteristics of light-emitting diode (LED) luminaires with different types of drivers and applications at amendment of the supply voltage are presented in the paper. Trends of the change in the electric current, real power, harmonic currents, total harmonic distortion and power factor for eleven LED luminaires with two type of drivers - pulse width modulation and bridge rectifier with capacitive divider, when varying the supply voltage are measured, analysed and presented in tabular, graphical and analytical form.
2020 Fifth Junior Conference on Lighting (Lighting), 2020
Study of the photometric and the colorimetric characteristics of the optical systems of LED domes... more Study of the photometric and the colorimetric characteristics of the optical systems of LED domestic lamps is done in this paper. The results for the measured maximum luminous intensity, beam angle, distribution of the luminous fluxes in spatial zones and light distribution curves of the bare LEDs lamp and LED lamps with different optical systems are presented. The efficiency losses in the optical systems of the tested LED domestic lamps are shown. A conclusion in terms of the realized photometric indicators and achieved total efficiency of the LED lamp optical system with various diffuser materials is done. Comparative results of measured colorimetric parameters of tested LED lamps as dominant wavelength, color rendering index and correlated color temperature for bare LEDs and LED lamps with optical system are presented.
2020 Fifth Junior Conference on Lighting (Lighting)
Study of the photometric and the colorimetric characteristics of the optical systems of LED domes... more Study of the photometric and the colorimetric characteristics of the optical systems of LED domestic lamps is done in this paper. The results for the measured maximum luminous intensity, beam angle, distribution of the luminous fluxes in spatial zones and light distribution curves of the bare LEDs lamp and LED lamps with different optical systems are presented. The efficiency losses in the optical systems of the tested LED domestic lamps are shown. A conclusion in terms of the realized photometric indicators and achieved total efficiency of the LED lamp optical system with various diffuser materials is done. Comparative results of measured colorimetric parameters of tested LED lamps as dominant wavelength, color rendering index and correlated color temperature for bare LEDs and LED lamps with optical system are presented.
В настоящата разработка се представят резултати от проект за модернизация на осветителна уредба в... more В настоящата разработка се представят резултати от проект за модернизация на осветителна уредба в учебна сграда в ТУ-Габрово с LED осветители. Извършено е обследване на съществуващото осветление в сградата, 3D моделиране на отделните помещения с отчитане на естественото осветление и вариантни светлотехнически изчисления с нови LED осветители. Приложени са резултати от изчисляване и оценка на енергийната ефективност на съществуващото и новото LED осветление, съгласно изискванията на стандарт БДС EN 15193:2009. Направена е технико-икономическа оценка на предлаганата модернизация на осветлението в сградата с LED осветители. / This paper presents some results of project for modernization of the lighting system in the academic building at the Technical University of Gabrovo with LED luminaires. Energy audit of existing lighting in the building, 3D modeling of individual rooms and variant lighting calculations including natural lighting with new LED lighting are carried out. Results from ...
The paper presents iterative optimization of the Monte Carlo raytracing settings for photometric ... more The paper presents iterative optimization of the Monte Carlo raytracing settings for photometric analysis of the optical system of industrial light-emitting diode (LED) luminaires with lenses. The research has been done about the influence of the main parameters of the raytracing settings (number of traced rays, number of ray reactions and weight of ray) on the accuracy of the quantitative and qualitative photometric analysis results. Tabular and graphical representations of the results are shown. The optimal Monte Carlo raytracing parameters for two different lens optical system types of LED luminaires are selected.
2021 Sixth Junior Conference on Lighting (Lighting)
The paper presents an implementation of a battery charge regulation device for a backup supply of... more The paper presents an implementation of a battery charge regulation device for a backup supply of photovoltaic LED lighting system at the Technical University of Gabrovo. Selection and sizing of the components with which the module is built are done. Principal electrical and block diagrams are presented. Tabular and graphical experimental results from charge the battery with the developed device are shown.
2023 Eight Junior Conference on Lighting (Lighting)
2023 Eight Junior Conference on Lighting (Lighting)
2023 Eight Junior Conference on Lighting (Lighting)
ENVIRONMENT. TECHNOLOGIES. RESOURCES. Proceedings of the International Scientific and Practical Conference
The quality of the marked surfaces changes the optical characteristics. The aim of the study is t... more The quality of the marked surfaces changes the optical characteristics. The aim of the study is to optimize the contrast in laser marking of Steel 75. The influence of the step in the raster marking and the influence of the repetition frequency of the pulses on the reflection coefficient were analysed. The experimental investigations of the reflectance were carried out using a spectrophotometer. For the marked samples, it was found that when directing electromagnetic radiation with a wavelength in the studied range, there are areas with absorption and reflection of light. The reflectance is plotted as a function of marking step and laser frequency for the marked Steel 75 samples.
2022 Seventh Junior Conference on Lighting (Lighting)
В настоящата разработка се представят резултати от проект за модернизация на осветителна уредба в... more В настоящата разработка се представят резултати от проект за модернизация на осветителна уредба в учебна сграда в ТУ-Габрово с LED осветители. Извършено е обследване на съществуващото осветление в сградата, 3D моделиране на отделните помещения с отчитане на естественото осветление и вариантни светлотехнически изчисления с нови LED осветители. Приложени са резултати от изчисляване и оценка на енергийната ефективност на съществуващото и новото LED осветление, съгласно изискванията на стандарт БДС EN 15193:2009. Направена е технико-икономическа оценка на предлаганата модернизация на осветлението в сградата с LED осветители. / This paper presents some results of project for modernization of the lighting system in the academic building at the Technical University of Gabrovo with LED luminaires. Energy audit of existing lighting in the building, 3D modeling of individual rooms and variant lighting calculations including natural lighting with new LED lighting are carried out. Results from ...
The paper presents technical and economic data on the development of photovoltaic electricity in ... more The paper presents technical and economic data on the development of photovoltaic electricity in Bulgaria over the last 10 years. The mix of different types of conventional and renewable energy sources in the country's electricity system is shown. The changes in the installed photovoltaic capacities and the price of electricity generated by them for the studied period are shown in tabular and graphical form. The number of photovoltaic power plants and their distribution by groups of individual powers are given. Brief technical and economic data for some of the largest photovoltaic power plants in Bulgaria are provided. Data analysis shows a short period of rapid development of highcapacity photovoltaic power plants construction after the introduction of high feed-in tariff for the purchase of photovoltaic electricity, as well as the influence of the installed photovoltaic capacities on the market change of the feed-in tariff over time. Feed-in tariff cost decreases remarkably with the increase of the installed photovoltaic capacity and even shows removal tendency for larger-capacity photovoltaic power plants. Examples of the economic profitability of grid-connected and autonomous photovoltaic systems in Bulgaria are given. The analysis and conclusions of the paper could be useful in determining new government policies and setting new market conditions to promote the development of renewable energy sources in Bulgaria and other countries.
2018 Seventh Balkan Conference on Lighting (BalkanLight), 2018
The paper presents a results of software calculation and experimental measurement determination o... more The paper presents a results of software calculation and experimental measurement determination of unified glare rating (UGR) for two teacher rooms in an educational building. Three-dimensional computer modeling and multivariate UGR software calculation with light-emitting diode luminaires having different lighting distributions and taking into account the actual position and the line of sight of the observer are performed. A methodology for experimental measurement and determination of UGR has been proposed and demonstrated for the same two rooms. The results are presented in tabular and graphical form. A comparative analysis of the results obtained from the software calculations and the experimental determination of UGR is carried out. Conclusions have been made about the influence on the accuracy of the URG values obtained of the light distribution type of the luminaires, the location and orientation of the line of sight of the observer, and the choice of the background luminance surface.
Contemporary Materials, 2013
Photovoltaic power supply of street lighting has been developing rapidly in recent years. A stand... more Photovoltaic power supply of street lighting has been developing rapidly in recent years. A stand-alone photovoltaic (PV) system supplying light-emitting diode (LED) outdoor luminaires has been constructed in the Technical University of Gabrovo. A PV-LED system consists of a PV module, a storage battery, a solar controller, a LED lamp and a system for remote visualization of operating modes. Working processes for optimization of the night operating mode of LED luminaire have been studied. Data on electrical energy stored by the battery and consumed for lighting have been presented.
2019 Second Balkan Junior Conference on Lighting (Balkan Light Junior), 2019
A methodology for iterative optimization of optical systems for street LED luminaires intended fo... more A methodology for iterative optimization of optical systems for street LED luminaires intended for roads designed according to luminance requirement is proposed in the paper. The methodology comprises the following stages: iterative change of the shape of secondary lens of a computer model of the optical system, photometric analysis using the Monte Carlo raytracing method of the modelled three-dimensional optical systems to calculate their photometric characteristics, optimal road lighting calculations with an optimum criterion – maximum luminaire spacing meeting the requirements of standard for the selected M6 lighting class of the road, through the analysis of which the optimal solution is found.
2020 Fifth Junior Conference on Lighting (Lighting), 2020
Building and study of a three-dimensional model of an optical system of LED lamp for indoor light... more Building and study of a three-dimensional model of an optical system of LED lamp for indoor lighting and photometric analysis by using Monte Carlo raytracing method of the modelled optical system with a diffuser made of various transmissive materials, transmittance and scattering angle is done in this paper. The results for the calculated number of ray reaction, zonal luminous fluxes, beam angle, light distribution curves and efficiency of the LED lamp optical system for different materials of the modeled diffuser are presented. A conclusion in terms of the realized photometric indicators and achieved total efficiency of the LED lamp optical system with various diffuser materials is done.
2019 Second Balkan Junior Conference on Lighting (Balkan Light Junior), 2019
In the paper is proposed methodology for iterative three-dimensional computer modeling of seconda... more In the paper is proposed methodology for iterative three-dimensional computer modeling of secondary optical lenses for street LED luminaires by using of Photopia and AutoCAD software. The methodology allows achieving of various desired light distributions of the luminaires by iteratively modifying the three-dimensional shape of the secondary lens. The created three-dimensional models of optical lenses shown are tested by Monte Carlo raytracing photometric analysis. The results confirm the performance and the possibilities for application of the proposed methodology.
Results of the study of the change of electrical characteristics of light-emitting diode (LED) lu... more Results of the study of the change of electrical characteristics of light-emitting diode (LED) luminaires with different types of drivers and applications at amendment of the supply voltage are presented in the paper. Trends of the change in the electric current, real power, harmonic currents, total harmonic distortion and power factor for eleven LED luminaires with two type of drivers - pulse width modulation and bridge rectifier with capacitive divider, when varying the supply voltage are measured, analysed and presented in tabular, graphical and analytical form.
2020 Fifth Junior Conference on Lighting (Lighting), 2020
Study of the photometric and the colorimetric characteristics of the optical systems of LED domes... more Study of the photometric and the colorimetric characteristics of the optical systems of LED domestic lamps is done in this paper. The results for the measured maximum luminous intensity, beam angle, distribution of the luminous fluxes in spatial zones and light distribution curves of the bare LEDs lamp and LED lamps with different optical systems are presented. The efficiency losses in the optical systems of the tested LED domestic lamps are shown. A conclusion in terms of the realized photometric indicators and achieved total efficiency of the LED lamp optical system with various diffuser materials is done. Comparative results of measured colorimetric parameters of tested LED lamps as dominant wavelength, color rendering index and correlated color temperature for bare LEDs and LED lamps with optical system are presented.
2020 Fifth Junior Conference on Lighting (Lighting)
Study of the photometric and the colorimetric characteristics of the optical systems of LED domes... more Study of the photometric and the colorimetric characteristics of the optical systems of LED domestic lamps is done in this paper. The results for the measured maximum luminous intensity, beam angle, distribution of the luminous fluxes in spatial zones and light distribution curves of the bare LEDs lamp and LED lamps with different optical systems are presented. The efficiency losses in the optical systems of the tested LED domestic lamps are shown. A conclusion in terms of the realized photometric indicators and achieved total efficiency of the LED lamp optical system with various diffuser materials is done. Comparative results of measured colorimetric parameters of tested LED lamps as dominant wavelength, color rendering index and correlated color temperature for bare LEDs and LED lamps with optical system are presented.
В настоящата разработка се представят резултати от проект за модернизация на осветителна уредба в... more В настоящата разработка се представят резултати от проект за модернизация на осветителна уредба в учебна сграда в ТУ-Габрово с LED осветители. Извършено е обследване на съществуващото осветление в сградата, 3D моделиране на отделните помещения с отчитане на естественото осветление и вариантни светлотехнически изчисления с нови LED осветители. Приложени са резултати от изчисляване и оценка на енергийната ефективност на съществуващото и новото LED осветление, съгласно изискванията на стандарт БДС EN 15193:2009. Направена е технико-икономическа оценка на предлаганата модернизация на осветлението в сградата с LED осветители. / This paper presents some results of project for modernization of the lighting system in the academic building at the Technical University of Gabrovo with LED luminaires. Energy audit of existing lighting in the building, 3D modeling of individual rooms and variant lighting calculations including natural lighting with new LED lighting are carried out. Results from ...
The paper presents iterative optimization of the Monte Carlo raytracing settings for photometric ... more The paper presents iterative optimization of the Monte Carlo raytracing settings for photometric analysis of the optical system of industrial light-emitting diode (LED) luminaires with lenses. The research has been done about the influence of the main parameters of the raytracing settings (number of traced rays, number of ray reactions and weight of ray) on the accuracy of the quantitative and qualitative photometric analysis results. Tabular and graphical representations of the results are shown. The optimal Monte Carlo raytracing parameters for two different lens optical system types of LED luminaires are selected.
2021 Sixth Junior Conference on Lighting (Lighting)
The paper presents an implementation of a battery charge regulation device for a backup supply of... more The paper presents an implementation of a battery charge regulation device for a backup supply of photovoltaic LED lighting system at the Technical University of Gabrovo. Selection and sizing of the components with which the module is built are done. Principal electrical and block diagrams are presented. Tabular and graphical experimental results from charge the battery with the developed device are shown.