1.
Ivanov, S. C.; Ivanova, Y. N.
Optimization of switching performance of power MOSFET with active driver with dv/dt feedback Conference
2021, ISBN: 9781665435826.
Abstract | Links | BibTeX | Етикети: e, ee
@conference{Ivanov2021,
title = {Optimization of switching performance of power MOSFET with active driver with dv/dt feedback},
author = {S. C. Ivanov and Y. N. Ivanova},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85114912001\&doi=10.1109%2fELMA52514.2021.9503078\&partnerID=40\&md5=e0e4c86858ded19b24128a2dafcd4726},
doi = {10.1109/ELMA52514.2021.9503078},
isbn = {9781665435826},
year = {2021},
date = {2021-01-01},
urldate = {2021-01-01},
journal = {2021 17th Conference on Electrical Machines, Drives and Power Systems, ELMA 2021 - Proceedings},
abstract = {Using an active driver with feedback on a derivative of drain voltage dv/dt to reduce high-order harmonic frequencies and reduce active losses in MOSFET control is researched and analyzed in this paper. Studies have been performed in the control of R-L load and supply voltage 12V. A comparison is made between the exponential change of the current through the load in controlling with a standard driver and change of current when driving with active driver. The article found that the active driver reduces the active power losses on the transistor. The studied active driver is suitable for control of DC-DC converters operating by the method of pulse-width modulation. © 2021 IEEE.},
keywords = {e, ee},
pubstate = {published},
tppubtype = {conference}
}
Using an active driver with feedback on a derivative of drain voltage dv/dt to reduce high-order harmonic frequencies and reduce active losses in MOSFET control is researched and analyzed in this paper. Studies have been performed in the control of R-L load and supply voltage 12V. A comparison is made between the exponential change of the current through the load in controlling with a standard driver and change of current when driving with active driver. The article found that the active driver reduces the active power losses on the transistor. The studied active driver is suitable for control of DC-DC converters operating by the method of pulse-width modulation. © 2021 IEEE.
2.
Budakova, D.; Petrova-Dimitrova, V.; Dakovski, L.
Smart broker agent learning how to reach appropriate goal by making appropriate compromises Conference
vol. 1, 2021, ISBN: 9789897584848.
Abstract | Links | BibTeX | Етикети: cst
@conference{Budakova2021181,
title = {Smart broker agent learning how to reach appropriate goal by making appropriate compromises},
author = {D. Budakova and V. Petrova-Dimitrova and L. Dakovski},
editor = {van den Herik J. Steels L. Rocha A.P.},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85103860936\&partnerID=40\&md5=067a1bdd3c8e6ce1a412f6ca31e15c58},
isbn = {9789897584848},
year = {2021},
date = {2021-01-01},
urldate = {2021-01-01},
journal = {ICAART 2021 - Proceedings of the 13th International Conference on Agents and Artificial Intelligence},
volume = {1},
pages = {181-188},
abstract = {In this paper a new Smart Broker Learning Agent (SBLA) has been proposed, which trains to find the most acceptable solution to a given problem, according to the individual requirements and emotions of a particular user. For this purpose, a new structure of the agent has been proposed and reinforcement-learning algorithm has been used. When the scenarios and criteria under consideration are complex, and when mixed emotions arise, it may be necessary to compromise on certain criteria in order to achieve the goal. Then knowledge of the preferences and emotions of the particular user is needed. In these cases, the SBLA does not allow compromises that are unacceptable to this user. The structure and the way of acting of the agent have been considered. The knowledge that the SBLA must have and the process of its formation have been described. The scenarios for solving a specific task and the conducted experiments have been presented. Some contributions, arising from the use of the proposed agent's architecture have been discussed, such as: the opportunity for the agent to explain decisions; to offer the most appropriate solution for each specific user; to avoid unacceptable compromises, to have empathy, and the greater approval of the offered solutions. © 2021 by SCITEPRESS - Science and Technology Publications, Lda. All rights reserved},
keywords = {cst},
pubstate = {published},
tppubtype = {conference}
}
In this paper a new Smart Broker Learning Agent (SBLA) has been proposed, which trains to find the most acceptable solution to a given problem, according to the individual requirements and emotions of a particular user. For this purpose, a new structure of the agent has been proposed and reinforcement-learning algorithm has been used. When the scenarios and criteria under consideration are complex, and when mixed emotions arise, it may be necessary to compromise on certain criteria in order to achieve the goal. Then knowledge of the preferences and emotions of the particular user is needed. In these cases, the SBLA does not allow compromises that are unacceptable to this user. The structure and the way of acting of the agent have been considered. The knowledge that the SBLA must have and the process of its formation have been described. The scenarios for solving a specific task and the conducted experiments have been presented. Some contributions, arising from the use of the proposed agent's architecture have been discussed, such as: the opportunity for the agent to explain decisions; to offer the most appropriate solution for each specific user; to avoid unacceptable compromises, to have empathy, and the greater approval of the offered solutions. © 2021 by SCITEPRESS - Science and Technology Publications, Lda. All rights reserved
3.
Petrova, G.; Spasov, G.; Iliev, I.
A Review on Applications of Low-resolution IR Array Sensors in Ambient-Assisted Living Conference
2021, ISBN: 9781665445184.
Abstract | Links | BibTeX | Етикети: cst, e
@conference{Petrova2021,
title = {A Review on Applications of Low-resolution IR Array Sensors in Ambient-Assisted Living},
author = {G. Petrova and G. Spasov and I. Iliev},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85119001857\&doi=10.1109%2fET52713.2021.9579477\&partnerID=40\&md5=efbd9ca279b727cda39d21f38b4dffee},
doi = {10.1109/ET52713.2021.9579477},
isbn = {9781665445184},
year = {2021},
date = {2021-01-01},
urldate = {2021-01-01},
journal = {2021 30th International Scientific Conference Electronics, ET 2021 - Proceedings},
abstract = {The present paper provides a review on applications of Low-resolution IR array sensors in Ambient-Assisted Living (AAL) monitoring systems. The review is focused on three main scenarios: indoor people detecting, localizing and counting; fall detection; indoor human activity detection and recognition. A comparative analysis of the reported results in the latest research studies has been carried out in terms of the type and position of the low-resolution IR array sensors used, the employed methods and image processing techniques and the achieved accuracy. The analysis shows that for fall detection and human activity recognition applications, the IR array sensors with 24times 32 pixels or multiple sensors arrangements with 4times 16, 16times 16 and 24times 32 pixels can provide sufficient accuracy and still preserving user privacy. © 2021 IEEE.},
keywords = {cst, e},
pubstate = {published},
tppubtype = {conference}
}
The present paper provides a review on applications of Low-resolution IR array sensors in Ambient-Assisted Living (AAL) monitoring systems. The review is focused on three main scenarios: indoor people detecting, localizing and counting; fall detection; indoor human activity detection and recognition. A comparative analysis of the reported results in the latest research studies has been carried out in terms of the type and position of the low-resolution IR array sensors used, the employed methods and image processing techniques and the achieved accuracy. The analysis shows that for fall detection and human activity recognition applications, the IR array sensors with 24times 32 pixels or multiple sensors arrangements with 4times 16, 16times 16 and 24times 32 pixels can provide sufficient accuracy and still preserving user privacy. © 2021 IEEE.
4.
Grigorova, T.; Vuchev, A.; Vuchev, S.
A Design Methodology for an LLC DC-DC Converter Operating above the Resonant Frequency Conference
2021, ISBN: 9781665445184.
Abstract | Links | BibTeX | Етикети: e
@conference{Grigorova2021,
title = {A Design Methodology for an LLC DC-DC Converter Operating above the Resonant Frequency},
author = {T. Grigorova and A. Vuchev and S. Vuchev},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85118987427\&doi=10.1109%2fET52713.2021.9579695\&partnerID=40\&md5=bfa9f257b5b45f191c7b38e8d25dbd57},
doi = {10.1109/ET52713.2021.9579695},
isbn = {9781665445184},
year = {2021},
date = {2021-01-01},
urldate = {2021-01-01},
journal = {2021 30th International Scientific Conference Electronics, ET 2021 - Proceedings},
abstract = {This paper discusses an accurate design methodology for an LLC DC-DC converter based on a precise analysis of the electromagnetic processes in the circuit using State Plane Analysis. The converter operates above the resonant frequency, and frequency control is applied to regulate the output power. Based on the obtained analytical dependences and expressions for the quantities on which the choice of the main circuit elements depends, a full-bridge LLC DC-DC converter was designed and simulated. The accuracy of the obtained results is very high (error of 1-2%). © 2021 IEEE.},
keywords = {e},
pubstate = {published},
tppubtype = {conference}
}
This paper discusses an accurate design methodology for an LLC DC-DC converter based on a precise analysis of the electromagnetic processes in the circuit using State Plane Analysis. The converter operates above the resonant frequency, and frequency control is applied to regulate the output power. Based on the obtained analytical dependences and expressions for the quantities on which the choice of the main circuit elements depends, a full-bridge LLC DC-DC converter was designed and simulated. The accuracy of the obtained results is very high (error of 1-2%). © 2021 IEEE.
5.
Penkov, St.; Taneva, A.
Chat programs in the frame of control system Conference
vol. 54, no. 13, 2021, ISSN: 24058963.
Abstract | Links | BibTeX | Етикети: cs
@conference{Penkov202152,
title = {Chat programs in the frame of control system},
author = {St. Penkov and A. Taneva},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85120684746\&doi=10.1016%2fj.ifacol.2021.10.417\&partnerID=40\&md5=b7833af8812224ed5df002bd06d16588},
doi = {10.1016/j.ifacol.2021.10.417},
issn = {24058963},
year = {2021},
date = {2021-01-01},
urldate = {2021-01-01},
journal = {IFAC-PapersOnLine},
volume = {54},
number = {13},
pages = {52-56},
abstract = {This paper presents a further development of Grafana project using LoRa media and chat software in the frame of control system. The combination of open SCADA for four process values monitoring and chat programs is the new. In this way a bot is created for sending predefined notifications as soon as occur in system and published. The so-called notification channel has been created for temperature, humidity, pressure and gas sensor for broad range of gases. The values are received by the BME 680 as a feedback in control system structure. The algorithm and programing to ensure the date exchange in real system are done. The verification, response and obtained messages, are presented as a result. The benefit is that instant messages with convenient data representation are achieved for chosen relevant time interval. This an example of integration between Grafana and messenger apps in new way. Due to integration of Grafana, using LoRa, and chats, the alarms can be set and notification can be transmitted over huge distances. © 2021 The Authors. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0/)},
keywords = {cs},
pubstate = {published},
tppubtype = {conference}
}
This paper presents a further development of Grafana project using LoRa media and chat software in the frame of control system. The combination of open SCADA for four process values monitoring and chat programs is the new. In this way a bot is created for sending predefined notifications as soon as occur in system and published. The so-called notification channel has been created for temperature, humidity, pressure and gas sensor for broad range of gases. The values are received by the BME 680 as a feedback in control system structure. The algorithm and programing to ensure the date exchange in real system are done. The verification, response and obtained messages, are presented as a result. The benefit is that instant messages with convenient data representation are achieved for chosen relevant time interval. This an example of integration between Grafana and messenger apps in new way. Due to integration of Grafana, using LoRa, and chats, the alarms can be set and notification can be transmitted over huge distances. © 2021 The Authors. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0/)
6.
Mecheva, T. A.; Kakanakov, N. R.
Traffic flow model based on real data Conference
2021, ISBN: 9781665445184.
Abstract | Links | BibTeX | Етикети: cst
@conference{Mecheva2021,
title = {Traffic flow model based on real data},
author = {T. A. Mecheva and N. R. Kakanakov},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85118967065\&doi=10.1109%2fET52713.2021.9579596\&partnerID=40\&md5=1d3ccb4282f0f6b1892e5e41f540e246},
doi = {10.1109/ET52713.2021.9579596},
isbn = {9781665445184},
year = {2021},
date = {2021-01-01},
urldate = {2021-01-01},
journal = {2021 30th International Scientific Conference Electronics, ET 2021 - Proceedings},
abstract = {Simulation models are vital in the process of design, evaluation, and predicting modern traffic systems. The selection of appropriate data and their adaptation to the simulator is one of the toughest tasks in transport simulation. The article presents a simple two-step model for traffic flow generation based on real data from road cameras. The privilege of the presented model in comparison to classic four-step model is its simplicity and the ability to operate with a small amount of data. The model is implemented over an area of three main intersections in the central Plovdiv. In the first step the origin and destination flows are calculated via Python. At the second step the road network and the calculated flows are set up to AIMSUN traffic simulator. The generated traffic flow is compared to the data from real measurements. The evaluation of the data shows that additional adjustment of the model is required. Directions for improvement are proposed: data purification before calculating traffic demand, investigation of model applicability with data from alternative measurements, and setting the traffic lights in dynamic mode. © 2021 IEEE.},
keywords = {cst},
pubstate = {published},
tppubtype = {conference}
}
Simulation models are vital in the process of design, evaluation, and predicting modern traffic systems. The selection of appropriate data and their adaptation to the simulator is one of the toughest tasks in transport simulation. The article presents a simple two-step model for traffic flow generation based on real data from road cameras. The privilege of the presented model in comparison to classic four-step model is its simplicity and the ability to operate with a small amount of data. The model is implemented over an area of three main intersections in the central Plovdiv. In the first step the origin and destination flows are calculated via Python. At the second step the road network and the calculated flows are set up to AIMSUN traffic simulator. The generated traffic flow is compared to the data from real measurements. The evaluation of the data shows that additional adjustment of the model is required. Directions for improvement are proposed: data purification before calculating traffic demand, investigation of model applicability with data from alternative measurements, and setting the traffic lights in dynamic mode. © 2021 IEEE.
7.
Pavlova, P. E.; Pachedjieva, B. K.
Investigation on the possibilities of tracking dynamic visibility changes in images Conference
2021, ISBN: 9781665445184.
Abstract | Links | BibTeX | Етикети: cst, e
@conference{Pavlova2021,
title = {Investigation on the possibilities of tracking dynamic visibility changes in images},
author = {P. E. Pavlova and B. K. Pachedjieva},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85119019255\&doi=10.1109%2fET52713.2021.9579821\&partnerID=40\&md5=9d42a6b86968d3572ac0584339836ac7},
doi = {10.1109/ET52713.2021.9579821},
isbn = {9781665445184},
year = {2021},
date = {2021-01-01},
urldate = {2021-01-01},
journal = {2021 30th International Scientific Conference Electronics, ET 2021 - Proceedings},
abstract = {This material describes a methodology for tracking the dynamics of weather phenomena in computer images. The investigation is based on parameters used in the currently available techniques for determination of fog, rain, snow and sun. The developed methodology relies on the, mean value, dispersion and correlated color temperature by processing the dark prior channel of colored images. Tracking is done for a set of data derived from restricted fields with different positioning in one image. The occurrence of an event is analysed on in sequences of images obtained in different weather phenomenon. The research is aimed at improving the processing of images at monitoring traffic. © 2021 IEEE.},
keywords = {cst, e},
pubstate = {published},
tppubtype = {conference}
}
This material describes a methodology for tracking the dynamics of weather phenomena in computer images. The investigation is based on parameters used in the currently available techniques for determination of fog, rain, snow and sun. The developed methodology relies on the, mean value, dispersion and correlated color temperature by processing the dark prior channel of colored images. Tracking is done for a set of data derived from restricted fields with different positioning in one image. The occurrence of an event is analysed on in sequences of images obtained in different weather phenomenon. The research is aimed at improving the processing of images at monitoring traffic. © 2021 IEEE.
8.
Raychev, R.; Georgiev, N.
Study of linear generators with and without rotating permanent magnets in their stator windings Conference
2021, ISBN: 9781665435826.
Abstract | Links | BibTeX | Етикети: ee
@conference{Raychev2021,
title = {Study of linear generators with and without rotating permanent magnets in their stator windings},
author = {R. Raychev and N. Georgiev},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85114954776\&doi=10.1109%2fELMA52514.2021.9503053\&partnerID=40\&md5=b7169ba77bb6f9f83b10b70d9a3dc5a0},
doi = {10.1109/ELMA52514.2021.9503053},
isbn = {9781665435826},
year = {2021},
date = {2021-01-01},
urldate = {2021-01-01},
journal = {2021 17th Conference on Electrical Machines, Drives and Power Systems, ELMA 2021 - Proceedings},
abstract = {The paper examines linear generators with and without rotating magnets in their stator windings. A three-dimensional model in dynamic mode has been synthesized with the help of ANSYS R19.1. The influence of the dimensions of the permanent magnets in the double sided translators on the electrical parameters of the generators has also been analyzed. Experimental studies of the generators have been performed to prove the accuracy of the simulation model. © 2021 IEEE.},
keywords = {ee},
pubstate = {published},
tppubtype = {conference}
}
The paper examines linear generators with and without rotating magnets in their stator windings. A three-dimensional model in dynamic mode has been synthesized with the help of ANSYS R19.1. The influence of the dimensions of the permanent magnets in the double sided translators on the electrical parameters of the generators has also been analyzed. Experimental studies of the generators have been performed to prove the accuracy of the simulation model. © 2021 IEEE.
9.
Nenchev, M.; Deneva, M.; Marinova, M.
vol. 1859, no. 1, 2021, ISSN: 17426588.
Abstract | Links | BibTeX | Етикети: cst, ee
@conference{Nenchev2021,
title = {Competitive light beam splitters based on complex interference wedged structures that use low-reflectivity components (Fresnel reflection)},
author = {M. Nenchev and M. Deneva and M. Marinova},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85104268254\&doi=10.1088%2f1742-6596%2f1859%2f1%2f012021\&partnerID=40\&md5=4f64ec553e7218abb7f9e286fda2d476},
doi = {10.1088/1742-6596/1859/1/012021},
issn = {17426588},
year = {2021},
date = {2021-01-01},
urldate = {2021-01-01},
journal = {Journal of Physics: Conference Series},
volume = {1859},
number = {1},
abstract = {We demonstrate that interference wedge structures suitably composed of wedged purely glass elements using Fresnel reflection only can be effectively employed for realization of competitive light beam splitters and filters (especially for high-power laser beams). The theoretical analysis, simulation and experimental testing show that for appropriately chosen parameters and for a suitably composed interference complex such structures can achieve a controlled variable transmission in a wide range (99%-~30%) and reflection from ~2% to ~70%. The traditional realization of purely glass splitters ensures no more than ~20% reflectivity. The splitters proposed are very compact sheet-like elements (e.g., 5×3×0.2 cm) and the splitting is implemented by sliding in the splitter's plane. Thus, the propagation direction of the formed beams is preserved. The incident beam on the purely glass splitter (no dielectric or metallic mirrors) can be of high power and the influence of the air humidity is strongly reduced; also, cleaning the filter surfaces presents no difficulties. A single splitter can work in a wide range of wavelengths (IR, visible) without polarization dependence for incident angles up to ~20°. © 2021 Published under licence by IOP Publishing Ltd.},
keywords = {cst, ee},
pubstate = {published},
tppubtype = {conference}
}
We demonstrate that interference wedge structures suitably composed of wedged purely glass elements using Fresnel reflection only can be effectively employed for realization of competitive light beam splitters and filters (especially for high-power laser beams). The theoretical analysis, simulation and experimental testing show that for appropriately chosen parameters and for a suitably composed interference complex such structures can achieve a controlled variable transmission in a wide range (99%-~30%) and reflection from ~2% to ~70%. The traditional realization of purely glass splitters ensures no more than ~20% reflectivity. The splitters proposed are very compact sheet-like elements (e.g., 5×3×0.2 cm) and the splitting is implemented by sliding in the splitter's plane. Thus, the propagation direction of the formed beams is preserved. The incident beam on the purely glass splitter (no dielectric or metallic mirrors) can be of high power and the influence of the air humidity is strongly reduced; also, cleaning the filter surfaces presents no difficulties. A single splitter can work in a wide range of wavelengths (IR, visible) without polarization dependence for incident angles up to ~20°. © 2021 Published under licence by IOP Publishing Ltd.
10.
Deneva, M.; Nenchev, M.
vol. 1859, no. 1, 2021, ISSN: 17426588.
Abstract | Links | BibTeX | Етикети: ee
@conference{Deneva2021,
title = {Integrated interference wedged structures as a basis for creating compact light beam splitters with improved parameters},
author = {M. Deneva and M. Nenchev},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85104248048\&doi=10.1088%2f1742-6596%2f1859%2f1%2f012020\&partnerID=40\&md5=5c5b544b0508486cc138f722415119d5},
doi = {10.1088/1742-6596/1859/1/012020},
issn = {17426588},
year = {2021},
date = {2021-01-01},
urldate = {2021-01-01},
journal = {Journal of Physics: Conference Series},
volume = {1859},
number = {1},
abstract = {Based on the idea of combining in one plate and in a puzzle-type of properly designed parts of planar sheet-like interference wedged structures (IWS), including the composed interference wedged structure (CIWS) developed by us, we show the possibility of realizing new integrated light beam splitters (for laser beams) that have useful competitive properties. Using our theoretical approach for analysis of IWS, simulations and test experiments, we show that such optimized splitters ensure a smooth splitting in an increased linear variation range of the transmission T (from ~ 80-95% to 5%) and reflection (R = 1-T), in combination with a large working range (linear splitting by sliding to more than ~15-20 mm). The low slope of the transmission variation permits one to split beams of diameter 3-5 mm; focusing the beam increases this range to more than ~15 mm. The control is performed by sliding the splitter in its plane (dimensions ~ 5×2×0.1 cm3) thus conserving the direction of the formed beams. No specific polarization is required and the use is possible of high-power laser beams. A suitable practical realization is the use of a mask technology for sequential deposition of necessary layers in integrated circuits. © 2021 Published under licence by IOP Publishing Ltd.},
keywords = {ee},
pubstate = {published},
tppubtype = {conference}
}
Based on the idea of combining in one plate and in a puzzle-type of properly designed parts of planar sheet-like interference wedged structures (IWS), including the composed interference wedged structure (CIWS) developed by us, we show the possibility of realizing new integrated light beam splitters (for laser beams) that have useful competitive properties. Using our theoretical approach for analysis of IWS, simulations and test experiments, we show that such optimized splitters ensure a smooth splitting in an increased linear variation range of the transmission T (from ~ 80-95% to 5%) and reflection (R = 1-T), in combination with a large working range (linear splitting by sliding to more than ~15-20 mm). The low slope of the transmission variation permits one to split beams of diameter 3-5 mm; focusing the beam increases this range to more than ~15 mm. The control is performed by sliding the splitter in its plane (dimensions ~ 5×2×0.1 cm3) thus conserving the direction of the formed beams. No specific polarization is required and the use is possible of high-power laser beams. A suitable practical realization is the use of a mask technology for sequential deposition of necessary layers in integrated circuits. © 2021 Published under licence by IOP Publishing Ltd.
11.
Stoykova, E.; Nazarova, D.; Nenchev, M.; Deneva, M.
Modelling of transmission for a stack of two Fizeau wedges with matched parameters Conference
vol. 11783, 2021, ISSN: 0277786X.
Abstract | Links | BibTeX | Етикети: ee
@conference{Stoykova2021,
title = {Modelling of transmission for a stack of two Fizeau wedges with matched parameters},
author = {E. Stoykova and D. Nazarova and M. Nenchev and M. Deneva},
editor = {Frenner K. Bodermann B.},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85109592789\&doi=10.1117%2f12.2592651\&partnerID=40\&md5=53be8a2777af7cbbb17f256de6506254},
doi = {10.1117/12.2592651},
issn = {0277786X},
year = {2021},
date = {2021-01-01},
urldate = {2021-01-01},
journal = {Proceedings of SPIE - The International Society for Optical Engineering},
volume = {11783},
abstract = {A conventional Fizeau wedge (FW) is built of two flat reflecting surfaces inclined at a small angle. They form a gap with linearly increasing thickness normally to the wedge ridge. Such FWs with apex angles of 5-100 microradians and 5-1000 micrometers thickness find application in optical metrology, spectroscopy and laser spectral control. The apex angle, the reflection coefficients and the refractive index in the gap form a unique interference pattern on both FW's sides. To benefit from a large free spectral range of thin wedges and high spectral resolution of thick wedges, recently we proposed a stack of two FWs with matched parameters. Matching provides the same change of the resonant wavelength at the same lateral displacement of both wedges. The aim of this study is to develop a technique for calculation of the resultant transmission of the stack of two matched wedges at plane wave illumination that is based on determination of the number and optical path differences of the rays leaving the stack at a given point on its rear surface. Only rays with non-negligible contribution as an amplitude are taken into account. Numerical simulation and experimental verification are provided. © 2021 SPIE.},
keywords = {ee},
pubstate = {published},
tppubtype = {conference}
}
A conventional Fizeau wedge (FW) is built of two flat reflecting surfaces inclined at a small angle. They form a gap with linearly increasing thickness normally to the wedge ridge. Such FWs with apex angles of 5-100 microradians and 5-1000 micrometers thickness find application in optical metrology, spectroscopy and laser spectral control. The apex angle, the reflection coefficients and the refractive index in the gap form a unique interference pattern on both FW's sides. To benefit from a large free spectral range of thin wedges and high spectral resolution of thick wedges, recently we proposed a stack of two FWs with matched parameters. Matching provides the same change of the resonant wavelength at the same lateral displacement of both wedges. The aim of this study is to develop a technique for calculation of the resultant transmission of the stack of two matched wedges at plane wave illumination that is based on determination of the number and optical path differences of the rays leaving the stack at a given point on its rear surface. Only rays with non-negligible contribution as an amplitude are taken into account. Numerical simulation and experimental verification are provided. © 2021 SPIE.
12.
Yatchev, I.; Balabozov, I.; Hinov, K.; Hadzhiev, I.; Gueorgiev, V.
Influence of the shape of the input pulses on the characteristics of hybrid electromagnetic system with magnetic flux modulation Journal Article
In: Electrical Engineering and Electromechanics, no. 3, pp. 3-7, 2021, ISSN: 2074272X.
Abstract | Links | BibTeX | Етикети: ee
@article{Yatchev20213,
title = {Influence of the shape of the input pulses on the characteristics of hybrid electromagnetic system with magnetic flux modulation},
author = {I. Yatchev and I. Balabozov and K. Hinov and I. Hadzhiev and V. Gueorgiev},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85120031146\&doi=10.20998%2f2074-272X.2021.3.01\&partnerID=40\&md5=fbf80aed5fb98c92c128f67e55cd745a},
doi = {10.20998/2074-272X.2021.3.01},
issn = {2074272X},
year = {2021},
date = {2021-01-01},
urldate = {2021-01-01},
journal = {Electrical Engineering and Electromechanics},
number = {3},
pages = {3-7},
abstract = {Introduction. Nowadays, the accelerated development of materials and technologies and the finding of new ones is a prerequisite for the improvement of well-known electromagnetic constructions used in various devices, as well as for the development of new ones. New construction of hybrid electromagnetic system with magnetic flux modulation (HEMSMM) is studied. The construction is composed of: ferromagnetic frame with air gaps, input and output coils and permanent magnets. Two input coils connected to the pulsed power supply are used to change the path of the generated by the permanent magnets constant magnetic flux. Input pulses with different shapes are applied to the input coils and signals in the output coils are obtained and compared. The main purpose of the work is to find the shape of the input pulses which leads to higher output power in comparison with the other shapes. Methods. Finite element method and COMSOL software is used for computer modelling of the proposed construction, where coupled electromagnetic field \textendash electric circuit analysis is carried out. Results. A mathematical and numerical 3D model of new HEMSMM construction is realised and studied. The model allows to calculate and compare power efficiency of the studied device, when input pulses with different shapes are applied. Practical value. The developed computer model enables the study of the HEMSMM and other electromagnetic devices at different operating modes. It can be further improved and used in the search for optimal parameters of a particular electromagnetic device. References 13, table 1, figures 13. © I. Yatchev, I. Balabozov, K. Hinov, I. Hadzhiev, V. Gueorgiev.},
keywords = {ee},
pubstate = {published},
tppubtype = {article}
}
Introduction. Nowadays, the accelerated development of materials and technologies and the finding of new ones is a prerequisite for the improvement of well-known electromagnetic constructions used in various devices, as well as for the development of new ones. New construction of hybrid electromagnetic system with magnetic flux modulation (HEMSMM) is studied. The construction is composed of: ferromagnetic frame with air gaps, input and output coils and permanent magnets. Two input coils connected to the pulsed power supply are used to change the path of the generated by the permanent magnets constant magnetic flux. Input pulses with different shapes are applied to the input coils and signals in the output coils are obtained and compared. The main purpose of the work is to find the shape of the input pulses which leads to higher output power in comparison with the other shapes. Methods. Finite element method and COMSOL software is used for computer modelling of the proposed construction, where coupled electromagnetic field – electric circuit analysis is carried out. Results. A mathematical and numerical 3D model of new HEMSMM construction is realised and studied. The model allows to calculate and compare power efficiency of the studied device, when input pulses with different shapes are applied. Practical value. The developed computer model enables the study of the HEMSMM and other electromagnetic devices at different operating modes. It can be further improved and used in the search for optimal parameters of a particular electromagnetic device. References 13, table 1, figures 13. © I. Yatchev, I. Balabozov, K. Hinov, I. Hadzhiev, V. Gueorgiev.
13.
Ivanova, Y.; Ivanov, S.
Dv/Dt Control through the Gate of a Field-Effect Transistor in Forward-Mode Converters Conference
2021, ISBN: 9781665440615.
Abstract | Links | BibTeX | Етикети: e, ee
@conference{Ivanova2021,
title = {Dv/Dt Control through the Gate of a Field-Effect Transistor in Forward-Mode Converters},
author = {Y. Ivanova and S. Ivanov},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85114125968\&doi=10.1109%2fELECTRONICA52725.2021.9513730\&partnerID=40\&md5=ca046cc88e447a9e5653b1b7543a7aba},
doi = {10.1109/ELECTRONICA52725.2021.9513730},
isbn = {9781665440615},
year = {2021},
date = {2021-01-01},
urldate = {2021-01-01},
journal = {12th National Conference with International Participation, ELECTRONICA 2021 - Proceedings},
abstract = {An important condition for increasing the efficiency of pulse converters is the reduction of active power losses on switch transistors during transients. In addition to reducing the duration of the on and off times, it is necessary to reduce the amplitude values of the currents and voltages of the switch transistor. This paper presents a study of the transients in the control of a forward pulsed voltage stabilizer. A comparative analysis was made between control of the switch transistor with a conventional and with an active driver with feedback on the derivative of drain voltage. The electromagnetic compatibility of the pulse converter is improved by reducing the maximum values of currents and voltages as well as the duration of the transients. © 2021 IEEE.},
keywords = {e, ee},
pubstate = {published},
tppubtype = {conference}
}
An important condition for increasing the efficiency of pulse converters is the reduction of active power losses on switch transistors during transients. In addition to reducing the duration of the on and off times, it is necessary to reduce the amplitude values of the currents and voltages of the switch transistor. This paper presents a study of the transients in the control of a forward pulsed voltage stabilizer. A comparative analysis was made between control of the switch transistor with a conventional and with an active driver with feedback on the derivative of drain voltage. The electromagnetic compatibility of the pulse converter is improved by reducing the maximum values of currents and voltages as well as the duration of the transients. © 2021 IEEE.
14.
Vuchev, A. S.; Grigorova, T. G.; Vuchev, S. A.
RMS Current Values in an LLC DC-DC Converter Operating above the Resonant Frequency Conference
2021, ISBN: 9781665445184.
Abstract | Links | BibTeX | Етикети: e
@conference{Vuchev2021,
title = {RMS Current Values in an LLC DC-DC Converter Operating above the Resonant Frequency},
author = {A. S. Vuchev and T. G. Grigorova and S. A. Vuchev},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85119015851\&doi=10.1109%2fET52713.2021.9579989\&partnerID=40\&md5=4451972184cb26910ea5acd6e627391e},
doi = {10.1109/ET52713.2021.9579989},
isbn = {9781665445184},
year = {2021},
date = {2021-01-01},
urldate = {2021-01-01},
journal = {2021 30th International Scientific Conference Electronics, ET 2021 - Proceedings},
abstract = {An algorithm for calculating root mean square (RMS) values of the currents through the elements of a full bridge LLC DC-DC converter is presented. Equations obtained on the base of State Plane Analysis for operation above the resonant frequency are used. The influence of the tank inductances ratio and the operating frequency is investigated using graphical representation. Computer simulations are performed for verification of the theoretical results. © 2021 IEEE.},
keywords = {e},
pubstate = {published},
tppubtype = {conference}
}
An algorithm for calculating root mean square (RMS) values of the currents through the elements of a full bridge LLC DC-DC converter is presented. Equations obtained on the base of State Plane Analysis for operation above the resonant frequency are used. The influence of the tank inductances ratio and the operating frequency is investigated using graphical representation. Computer simulations are performed for verification of the theoretical results. © 2021 IEEE.
15.
Mecheva, T; Kakanakov, N
Cybersecurity in intelligent transportation systems Journal Article
In: Computers, vol. 9, no. 4, pp. 1-12, 2020, ISSN: 2073431X, (cited By 0).
Abstract | Links | BibTeX | Етикети: cst
@article{Mecheva20201,
title = {Cybersecurity in intelligent transportation systems},
author = {T Mecheva and N Kakanakov},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85092441448\&doi=10.3390%2fcomputers9040083\&partnerID=40\&md5=695507274a3ee8ac9c66098512cfc13f},
doi = {10.3390/computers9040083},
issn = {2073431X},
year = {2020},
date = {2020-01-01},
journal = {Computers},
volume = {9},
number = {4},
pages = {1-12},
publisher = {MDPI AG},
abstract = {Intelligent Transportation Systems (ITS) are emerging field characterized by complex data model, dynamics and strict time requirements. Ensuring cybersecurity in ITS is a complex task on which the safety and efficiency of transportation depends. The imposition of standards for a comprehensive architecture, as well as specific security standards, is one of the key steps in the evolution of ITS. The article examines the general outlines of the ITS architecture and security issues. The main focus of security approaches is: configuration and initialization of the devices during manufacturing at perception layer; anonymous authentication of nodes in VANET at network layer; defense of fog-based structures at support layer and description and standardization of the complex model of data and metadata and defense of systems, based on AI at application layer. The article oversees some conventional methods as network segmentation and cryptography that should be adapted in order to be applied in ITS cybersecurity. The focus is on innovative approaches that have recently been trying to find their place in ITS security strategies. These approaches includes blockchain, bloom filter, fog computing, artificial intelligence, game theory and ontologies. In conclusion, a correlation is made between the commented methods, the problems they solve and the architectural layers in which they are applied. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.},
note = {cited By 0},
keywords = {cst},
pubstate = {published},
tppubtype = {article}
}
Intelligent Transportation Systems (ITS) are emerging field characterized by complex data model, dynamics and strict time requirements. Ensuring cybersecurity in ITS is a complex task on which the safety and efficiency of transportation depends. The imposition of standards for a comprehensive architecture, as well as specific security standards, is one of the key steps in the evolution of ITS. The article examines the general outlines of the ITS architecture and security issues. The main focus of security approaches is: configuration and initialization of the devices during manufacturing at perception layer; anonymous authentication of nodes in VANET at network layer; defense of fog-based structures at support layer and description and standardization of the complex model of data and metadata and defense of systems, based on AI at application layer. The article oversees some conventional methods as network segmentation and cryptography that should be adapted in order to be applied in ITS cybersecurity. The focus is on innovative approaches that have recently been trying to find their place in ITS security strategies. These approaches includes blockchain, bloom filter, fog computing, artificial intelligence, game theory and ontologies. In conclusion, a correlation is made between the commented methods, the problems they solve and the architectural layers in which they are applied. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.
16.
Stefanov, S B; Georgiev, A P
vol. 878, no. 1, Institute of Physics Publishing, 2020, ISSN: 17578981, (cited By 0).
Abstract | Links | BibTeX | Етикети: ee
@conference{Stefanov2020,
title = {Study of the technical and economic efficiency and the possibilities for the construction of photovoltaic power plant above the roof structures of transformer power substations 20/0,4 kV and their service areas},
author = {S B Stefanov and A P Georgiev},
editor = {Shakev Ahmed N S Nikolov V. Petrov M.},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85088985813\&doi=10.1088%2f1757-899X%2f878%2f1%2f012014\&partnerID=40\&md5=1ea1205e4217af8b5d69ffd6abddff64},
doi = {10.1088/1757-899X/878/1/012014},
issn = {17578981},
year = {2020},
date = {2020-01-01},
journal = {IOP Conference Series: Materials Science and Engineering},
volume = {878},
number = {1},
publisher = {Institute of Physics Publishing},
abstract = {This report examines the possibility of constructing photovoltaic systems above concrete complete transformer posts to the medium voltage distribution networks. It has been analysed what capacities could be built depending on the size of the concrete facilities and their service areas, and what would be their economic and electricity efficiency. The main results of the analyses made show that this idea is not devoid of economic and electricity logic. © 2020 IOP Publishing Ltd. All rights reserved.},
note = {cited By 0},
keywords = {ee},
pubstate = {published},
tppubtype = {conference}
}
This report examines the possibility of constructing photovoltaic systems above concrete complete transformer posts to the medium voltage distribution networks. It has been analysed what capacities could be built depending on the size of the concrete facilities and their service areas, and what would be their economic and electricity efficiency. The main results of the analyses made show that this idea is not devoid of economic and electricity logic. © 2020 IOP Publishing Ltd. All rights reserved.
17.
Petrov, V
Nonlinear backstepping tracking control of DC motor driven inverted pendulum Conference
vol. 878, no. 1, Institute of Physics Publishing, 2020, ISSN: 17578981, (cited By 0).
Abstract | Links | BibTeX | Етикети: cs
@conference{Petrov2020,
title = {Nonlinear backstepping tracking control of DC motor driven inverted pendulum},
author = {V Petrov},
editor = {Shakev Ahmed N S Nikolov V. Petrov M.},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85089010269\&doi=10.1088%2f1757-899X%2f878%2f1%2f012002\&partnerID=40\&md5=8145ab19a258fd55d28864cd4fddb5cb},
doi = {10.1088/1757-899X/878/1/012002},
issn = {17578981},
year = {2020},
date = {2020-01-01},
journal = {IOP Conference Series: Materials Science and Engineering},
volume = {878},
number = {1},
publisher = {Institute of Physics Publishing},
abstract = {The paper presents nonlinear backstepping approach for nonlinear control design applied to a DC motor driven inverted pendulum system. The nonlinear closed-loop system designed simultaneously tracks exponentially desired reference trajectory with overdamped response specifications. A simulation example is given for illustration. © 2020 IOP Publishing Ltd. All rights reserved.},
note = {cited By 0},
keywords = {cs},
pubstate = {published},
tppubtype = {conference}
}
The paper presents nonlinear backstepping approach for nonlinear control design applied to a DC motor driven inverted pendulum system. The nonlinear closed-loop system designed simultaneously tracks exponentially desired reference trajectory with overdamped response specifications. A simulation example is given for illustration. © 2020 IOP Publishing Ltd. All rights reserved.
18.
Popov, R; Paunkov, N; Rangelova, V; Georgiev, A
Study of hybrid thermal system with photovoltaic panels using virtual instruments Journal Article
In: Renewable Energy, vol. 154, pp. 1053-1064, 2020, ISSN: 09601481, (cited By 2).
Abstract | Links | BibTeX | Етикети: ee
@article{Popov20201053,
title = {Study of hybrid thermal system with photovoltaic panels using virtual instruments},
author = {R Popov and N Paunkov and V Rangelova and A Georgiev},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85082117517\&doi=10.1016%2fj.renene.2020.03.024\&partnerID=40\&md5=7087a9defab273b1e11a4602fbe66fed},
doi = {10.1016/j.renene.2020.03.024},
issn = {09601481},
year = {2020},
date = {2020-01-01},
journal = {Renewable Energy},
volume = {154},
pages = {1053-1064},
publisher = {Elsevier Ltd},
abstract = {In this paper, а novel set of virtual instruments has been developed and approved. It allows for providing on-line or off-line uncertainty calculations and statistical hypothesis testing. A novel instrument “Expansion card” has been developed in our laboratory. Several tests were performed to check the performance of some hybrid heating installation components. For this purpose, a hybrid solar thermal system, combined with photovoltaic panels has been designed and constructed by the authors. The system consists of two basic subsystems: thermal part and electrical part. Both are equipped with measuring devices to form a complex virtual test instrument. The aim of the tests was to characterize the energy efficiency of a low-cost PV/T panel construction and to check the proper operation of the developed virtual instrument tools. The tests showed that there was poor thermal contact between the pipe and the backside of the cell's plate. That lead to the modification of the PV/T panel's construction. It was also found that at higher temperatures, the heat exchange in the PV/T panel deteriorates and its energy output is better. So the parallel connection should be preferable for PV/T panel heat exchangers. © 2020 Elsevier Ltd},
note = {cited By 2},
keywords = {ee},
pubstate = {published},
tppubtype = {article}
}
In this paper, а novel set of virtual instruments has been developed and approved. It allows for providing on-line or off-line uncertainty calculations and statistical hypothesis testing. A novel instrument “Expansion card” has been developed in our laboratory. Several tests were performed to check the performance of some hybrid heating installation components. For this purpose, a hybrid solar thermal system, combined with photovoltaic panels has been designed and constructed by the authors. The system consists of two basic subsystems: thermal part and electrical part. Both are equipped with measuring devices to form a complex virtual test instrument. The aim of the tests was to characterize the energy efficiency of a low-cost PV/T panel construction and to check the proper operation of the developed virtual instrument tools. The tests showed that there was poor thermal contact between the pipe and the backside of the cell's plate. That lead to the modification of the PV/T panel's construction. It was also found that at higher temperatures, the heat exchange in the PV/T panel deteriorates and its energy output is better. So the parallel connection should be preferable for PV/T panel heat exchangers. © 2020 Elsevier Ltd
19.
Pavlova, P E; Pachedjieva, B K
Institute of Electrical and Electronics Engineers Inc., 2020, ISBN: 9781728174266, (cited By 0).
Abstract | Links | BibTeX | Етикети: cst, e
@conference{Pavlova2020,
title = {Methodology for numerical assessments of the quality of cloud fields images used in time mutability method},
author = {P E Pavlova and B K Pachedjieva},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85097077784\&doi=10.1109%2fET50336.2020.9238283\&partnerID=40\&md5=3a7c42178bcd4270b32024f9fd51e79c},
doi = {10.1109/ET50336.2020.9238283},
isbn = {9781728174266},
year = {2020},
date = {2020-01-01},
journal = {2020 29th International Scientific Conference Electronics, ET 2020 - Proceedings},
publisher = {Institute of Electrical and Electronics Engineers Inc.},
abstract = {The methodology described below supports the time mutability method for estimating cloud drift velocity. A technique for determination numerical values of the contrast and impulse noise level in images of cloud fields is presented. The contrast for the entire image and the level of the impulse noise for the entire image and in addition-in angular directions have been calculated in accordance with the method for drift velocity estimation. The evaluations have been realized by special developed software modules. © 2020 IEEE.},
note = {cited By 0},
keywords = {cst, e},
pubstate = {published},
tppubtype = {conference}
}
The methodology described below supports the time mutability method for estimating cloud drift velocity. A technique for determination numerical values of the contrast and impulse noise level in images of cloud fields is presented. The contrast for the entire image and the level of the impulse noise for the entire image and in addition-in angular directions have been calculated in accordance with the method for drift velocity estimation. The evaluations have been realized by special developed software modules. © 2020 IEEE.
20.
Pachedjieva, B K; Pavlova, P E
Institute of Electrical and Electronics Engineers Inc., 2020, ISBN: 9781728174266, (cited By 0).
Abstract | Links | BibTeX | Етикети: cst, e
@conference{Pachedjieva2020,
title = {Stochastic objects velocity estimation using Modified Time Mutability Method, based on two-dimensional images},
author = {B K Pachedjieva and P E Pavlova},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85097062584\&doi=10.1109%2fET50336.2020.9238177\&partnerID=40\&md5=5c643c35c3c2cdc7dc22e5d166f958ce},
doi = {10.1109/ET50336.2020.9238177},
isbn = {9781728174266},
year = {2020},
date = {2020-01-01},
journal = {2020 29th International Scientific Conference Electronics, ET 2020 - Proceedings},
publisher = {Institute of Electrical and Electronics Engineers Inc.},
abstract = {The time mutability method allows estimation of drift velocity of stochastic objects basing on sequences of their images. A procedure for constructing and selecting rotational radial-sections from two-dimensional images through which a velocity field can be constructed is proposed. The constructed sections are applied to determine the velocity field of a cloud field based on a series of its two-dimensional images. Numerical examples, illustrated by graphic material, have been shown. © 2020 IEEE.},
note = {cited By 0},
keywords = {cst, e},
pubstate = {published},
tppubtype = {conference}
}
The time mutability method allows estimation of drift velocity of stochastic objects basing on sequences of their images. A procedure for constructing and selecting rotational radial-sections from two-dimensional images through which a velocity field can be constructed is proposed. The constructed sections are applied to determine the velocity field of a cloud field based on a series of its two-dimensional images. Numerical examples, illustrated by graphic material, have been shown. © 2020 IEEE.