Tanya Trenkova - Academia.edu (original) (raw)
Papers by Tanya Trenkova
Proceedings of the International Conference on Evolutionary Computation, 2010
In this work a modified multi-population genetic algorithm (MPGA) without the performance of the ... more In this work a modified multi-population genetic algorithm (MPGA) without the performance of the mutation operator is proposed. The idea is to reduce the convergence time and therefore to increase the identification procedure effectiveness for on-line application of the algorithm. Modified MPGA, classical multipopulation GA and two other modifications are tested for parameter identification problem of an E. coli non-linear fed-batch cultivation model. The contribution of each modification measure to the performance improvement is demonstrated. The obtained results show that the highest accuracy for parameter identification of the considered model is achieved with the multipopulation GA with Modification 1. The best calculation time is shown by the multipopulation GA without mutation.
Proceedings of the 4th International Joint Conference on Computational Intelligence, 2012
In this paper, Firefly algorithms (FA) and Genetic algorithms (GA) are applied to parameter ident... more In this paper, Firefly algorithms (FA) and Genetic algorithms (GA) are applied to parameter identification problem of a non-linear mathematical model of the E. coli cultivation process. A system of ordinary differential equations is proposed to model the growth of the bacteria, substrate utilization and acetate formation. Parameter optimization is performed using a real experimental data set from an E. coli MC4110 fed-batch cultivation process. In the considered non-linear mathematical model, the parameters that should be estimated are maximum specific growth rate, two saturation constants and two yield coefficients. Parameters of both meta-heuristics are tuned on the basis of several pre-tests according to the optimization problem considered here. Based on the numerical and simulation result, it is shown that the model obtained by the FA is more accurate and adequate than the one obtained using the GA. Presented results prove FA superiority and powerfulness in solving non-linear dynamic model of cultivation processes. 164 Roeva O. and Trenkova T..
BIOMATH, 2012
In this paper the metaheuristic Simulated Annealing (SA) is applied for parameter identification ... more In this paper the metaheuristic Simulated Annealing (SA) is applied for parameter identification of non-linear model of cultivation process. SA algorithm is a stochastic relaxation technique, using the Metropolis algorithm based on the Boltzmann distribution in statistical mechanics, for solving nonconvex optimization problems. A real E. coli MC4110 fed-batch cultivation process is considered. The mathematical model is presented by a system of five ordinary differential equations, describing the regarded cultivation process variables - biomass, substrate, acetate, dissolved oxygen and bioreactor volume increasing. The obtained criteria values show that the developed model is adequate and has a high degree of accuracy. The presented results are a confirmation of successful application of the SA algorithm and of the choice of SA algorithm parameters.
In this paper, Firefly algorithms (FA) and Genetic algorithms (GA) are applied to parameter ident... more In this paper, Firefly algorithms (FA) and Genetic algorithms (GA) are applied to parameter identification problem of a non-linear mathematical model of the E. coli cultivation process. A system of ordinary differential equations is proposed to model the growth of the bacteria, substrate utilization and acetate formation. Parameter optimization is performed using a real experimental data set from an E. coli MC4110 fed-batch cultivation process. In the considered non-linear mathematical model, the parameters that should be estimated are maximum specific growth rate, two saturation constants and two yield coefficients. Parameters of both meta-heuristics are tuned on the basis of several pre-tests according to the optimization problem considered here. Based on the numerical and simulation result, it is shown that the model obtained by the FA is more accurate and adequate than the one obtained using the GA. Presented results prove FA superiority and powerfulness in solving non-linear dynamic model of cultivation processes. 164 Roeva O. and Trenkova T..
Environmental Earth Sciences
In 2019 the Studena reservoir, the only water supply source for the town of Pernik in Bulgaria, a... more In 2019 the Studena reservoir, the only water supply source for the town of Pernik in Bulgaria, accumulated less than half of its normal annual inflow. This factor, together with an inadequate and delayed response by the water resource managers caused a severe water supply crisis in the fall and winter of that year. As this situation was unprecedented, investigations were undertaken to determine the cause of the low inflow to the reservoir using the model CLM3 and available climatic and spatial data, and data that were collected in the watershed for the reservoir. The study was conducted by simulating the hydrological processes that take place in the watershed, and the monthly inflows to the reservoir for the period 2017–2019. It was found that hydrological parameters produced in the calibrated model were similar to those measured in the field and by another model. The achieved agreement was considered to be satisfactory given the complexity of their nature and assessment methods. The result of the study convincingly confirmed that the main reason for the poor inflow to the reservoir in 2019 was the low precipitation in this year and, above all, the scarce snowfall in the winter months. Although the total annual precipitation falling in the region during the period 2017–2019 has not changed significantly, but the seasonal distribution of precipitation has changed. In particular, the amount of precipitation that falls in snowfalls has declined and reached a minimum in 2019. These decreases are due to the increase in the average air temperature of 1 °C which causes the observed decreases in the runoff.
AIP Conference Proceedings, 2019
The unsaturated soil zone is a link between the surface and the groundwater environment. Its comp... more The unsaturated soil zone is a link between the surface and the groundwater environment. Its comprehensive physical representation, adopted by the Community Land Model (CLM), follows the integrated interaction between the soil matrix, plant roots and wetness dynamics. Land Surface Models (in the case CLM) are well developed tools accounting for: water and energy fluxes input from the atmosphere, energy conduction, water infiltration, further downward penetration throught the soil zone during precipitation and the upward evapotranspiration flow during dry conditions. The net gravitational water flow forms the groundwater recharge. The paper presents the application of the CLM model for groundwater recharge calculation for the Bulgarian territory. Additionally, the influence of the assumed in the model length of time discretization of the atmospheric forcings approximation on the accuracy of the results is studied. Available field data are used for comparison analyses.The unsaturated soil zone is a link between the surface and the groundwater environment. Its comprehensive physical representation, adopted by the Community Land Model (CLM), follows the integrated interaction between the soil matrix, plant roots and wetness dynamics. Land Surface Models (in the case CLM) are well developed tools accounting for: water and energy fluxes input from the atmosphere, energy conduction, water infiltration, further downward penetration throught the soil zone during precipitation and the upward evapotranspiration flow during dry conditions. The net gravitational water flow forms the groundwater recharge. The paper presents the application of the CLM model for groundwater recharge calculation for the Bulgarian territory. Additionally, the influence of the assumed in the model length of time discretization of the atmospheric forcings approximation on the accuracy of the results is studied. Available field data are used for comparison analyses.
AIP Conference Proceedings, 2019
Applied Ecology and Environmental Research
The paper discusses the impact of winter seasons climate change on crop yields in the South Centr... more The paper discusses the impact of winter seasons climate change on crop yields in the South Central Region of Bulgaria. Twenty-two years long field observations show a progressive increase in air temperature and a decrease in snow cover in the winter seasons. The reduction of snow and the air temperature rise are supposed to lead to reduction of water availability in the spring for the winter crops and respectively to lowering their yield. By compiling observed climatic data and those obtained through a spatially distributed climatic model for the region area analysed is the relationship between these climatic parameters and the respective harvest of the winter crops for the last 5 winter seasons. The observed in the analysed period winter crops yield does not show distinctly the supposed dependence on the decrease of the snowfall amount and snow cover residence time. The yields of the last winter season 2019/2020 with the least snow cover and 2 o C higher air temperature exceeded those of all other seasons. This effect is explained with the favourable combination of the high air temperature with the amount and monthly distribution of the precipitation in the season.
NATO Science for Peace and Security Series C: Environmental Security, 2009
Natural hazards and flood events are part of nature. In most cases, floods are caused by climatol... more Natural hazards and flood events are part of nature. In most cases, floods are caused by climatological phenomena, which are out of human control. The scale and frequency of floods are likely to increase in the future as a result of climate change, inappropriate river management and construction in flood risk areas. There has been a marked increase in vulnerability due to the number of people and economic assets located in flood risk zones. Two natural disasters such as drought and flood have effected on different parts of the earth as a result of increasing human's interference on global climate. In the recent years, our country was a witness in occurrence of floods and severe droughts, which has caused destruction of agricultural lands. The process of the delimitation of the endangered agricultural areas is a priority task for the Bulgarian scientists and the Water authorities. A research of the river basin of Mesta concerning such flood issues has been carried out. Hydrological analyses were made in order to get the probability of the maximum runoff. The obtained results were considered in different scenarios of flood events (water level or depth, flood extends), meeting the requirements of the European Union (EU) Flood Risk Management Directive. The presented research is a part of a project for young scientists about determination of the agricultural areas endangered by floods in the river Mesta watershed.
MATEC Web of Conferences, 2018
Estimating groundwater recharge is an important part of the water resources evaluation. In spite ... more Estimating groundwater recharge is an important part of the water resources evaluation. In spite of the numerous existing methods it continues to be not easy value to quantify. This is due to its dependence on many meteorological, hydrogeological, soil type and cover conditions and the impossibility for direct measurement. Employment of hydrological models in fact directly calculates the influence of the above cited natural factors. The Community Land Model (CLM3) being loaded with all land featuring data in global scale, including an adequate soil filtration process simulation by the Richards equation, together with the possibility for input of NCEP/NCAR Reanalyses database, featuring the meteorological effect, gives an opportunity to avoid to great extent the difficulties in groundwater (GW) recharge estimation. The paper presents the results from an experiment concerning GW recharge monthly estimation during 2013, worked out for the Kamchia river watershed in Bulgaria. The comput...
The advance in the web mapping technologies enabled the generation and use of vast amount of spat... more The advance in the web mapping technologies enabled the generation and use of vast amount of spatial data. First and foremost, challenge is the extraction of appropriate information from the excessive data overload. In this respect the needs of web-based GIS applications for fast and easy dissemination, display and sharing of spatial information are constantly growing. The work investigates some geovisualization techniques for user friendly data representation. A framework containing different data types is elaborated related to the utilization of spatial datasets for Yantra River Basin area. The prototype is developed to serve as a data-viewer for various users. The goal is to provide a comprehensive visualization tool for gaining better understanding from the available spatial data for the case study area. The application enables users to view, natural resources information for specific needs. The approach integrates only open source technologies for the development of the web-bas...
MATEC Web of Conferences, 2018
Estimating groundwater recharge is an important part of the water resources evaluation. In spite ... more Estimating groundwater recharge is an important part of the water resources evaluation. In spite of the numerous existing methods it continues to be not easy value to quantify. This is due to its dependence on many meteorological, hydrogeological, soil type and cover conditions and the impossibility for direct measurement. Employment of hydrological models in fact directly calculates the influence of the above cited natural factors. The Community Land Model (CLM3) being loaded with all land featuring data in global scale, including an adequate soil filtration process simulation by the Richards equation, together with the possibility for input of NCEP/NCAR Reanalyses database, featuring the meteorological effect, gives an opportunity to avoid to great extent the difficulties in groundwater (GW) recharge estimation. The paper presents the results from an experiment concerning GW recharge monthly estimation during 2013, worked out for the Kamchia river watershed in Bulgaria. The computed monthly and annual values are presented on GIS maps and are compared with existing assessments made by other methods. It is proved the good approach and the applicability of the method.
Water resources scheme, simulation model and GIS for the transboundary river basin of Struma have... more Water resources scheme, simulation model and GIS for the transboundary river basin of Struma have been developed as a part of the River Basin Management Plans (RBMP). The transboundary character of the river basin requires integrated water resources management. All considerable water resources and hydraulic relations between the water users and the environment are taken into consideration for the graphical scheme. The programme SIMYL has been applied and the functioning of the water resources system has been analyzed in different variants for water consumption and water resources. The calculated disturbance of the run-off at different stations in the river basin was given as an assessment of the anthropogenic pressure. Critical sections have been determined in accordance with the Water Frame Directive (WFD). The possible decisions of the basic problems of the river basin are analyzed in order to assist in the decision making process of integrated water resources management in the We...
ifigenia.org
In this work a modified multi-population genetic algorithm (MPGA) without the performance of the ... more In this work a modified multi-population genetic algorithm (MPGA) without the performance of the mutation operator is proposed. The idea is to reduce the convergence time and therefore to increase the identification procedure effectiveness for on-line application of the algorithm. Modified MPGA, classical multipopulation GA and two other modifications are tested for parameter identification problem of an E. coli non-linear fed-batch cultivation model. The contribution of each modification measure to the performance improvement is demonstrated. The obtained results show that the highest accuracy for parameter identification of the considered model is achieved with the multipopulation GA with Modification 1. The best calculation time is shown by the multipopulation GA without mutation. X S A J J J J min = + + →
Proceedings of the International Conference on Evolutionary Computation, 2010
In this work a modified multi-population genetic algorithm (MPGA) without the performance of the ... more In this work a modified multi-population genetic algorithm (MPGA) without the performance of the mutation operator is proposed. The idea is to reduce the convergence time and therefore to increase the identification procedure effectiveness for on-line application of the algorithm. Modified MPGA, classical multipopulation GA and two other modifications are tested for parameter identification problem of an E. coli non-linear fed-batch cultivation model. The contribution of each modification measure to the performance improvement is demonstrated. The obtained results show that the highest accuracy for parameter identification of the considered model is achieved with the multipopulation GA with Modification 1. The best calculation time is shown by the multipopulation GA without mutation.
Proceedings of the 4th International Joint Conference on Computational Intelligence, 2012
In this paper, Firefly algorithms (FA) and Genetic algorithms (GA) are applied to parameter ident... more In this paper, Firefly algorithms (FA) and Genetic algorithms (GA) are applied to parameter identification problem of a non-linear mathematical model of the E. coli cultivation process. A system of ordinary differential equations is proposed to model the growth of the bacteria, substrate utilization and acetate formation. Parameter optimization is performed using a real experimental data set from an E. coli MC4110 fed-batch cultivation process. In the considered non-linear mathematical model, the parameters that should be estimated are maximum specific growth rate, two saturation constants and two yield coefficients. Parameters of both meta-heuristics are tuned on the basis of several pre-tests according to the optimization problem considered here. Based on the numerical and simulation result, it is shown that the model obtained by the FA is more accurate and adequate than the one obtained using the GA. Presented results prove FA superiority and powerfulness in solving non-linear dynamic model of cultivation processes. 164 Roeva O. and Trenkova T..
BIOMATH, 2012
In this paper the metaheuristic Simulated Annealing (SA) is applied for parameter identification ... more In this paper the metaheuristic Simulated Annealing (SA) is applied for parameter identification of non-linear model of cultivation process. SA algorithm is a stochastic relaxation technique, using the Metropolis algorithm based on the Boltzmann distribution in statistical mechanics, for solving nonconvex optimization problems. A real E. coli MC4110 fed-batch cultivation process is considered. The mathematical model is presented by a system of five ordinary differential equations, describing the regarded cultivation process variables - biomass, substrate, acetate, dissolved oxygen and bioreactor volume increasing. The obtained criteria values show that the developed model is adequate and has a high degree of accuracy. The presented results are a confirmation of successful application of the SA algorithm and of the choice of SA algorithm parameters.
In this paper, Firefly algorithms (FA) and Genetic algorithms (GA) are applied to parameter ident... more In this paper, Firefly algorithms (FA) and Genetic algorithms (GA) are applied to parameter identification problem of a non-linear mathematical model of the E. coli cultivation process. A system of ordinary differential equations is proposed to model the growth of the bacteria, substrate utilization and acetate formation. Parameter optimization is performed using a real experimental data set from an E. coli MC4110 fed-batch cultivation process. In the considered non-linear mathematical model, the parameters that should be estimated are maximum specific growth rate, two saturation constants and two yield coefficients. Parameters of both meta-heuristics are tuned on the basis of several pre-tests according to the optimization problem considered here. Based on the numerical and simulation result, it is shown that the model obtained by the FA is more accurate and adequate than the one obtained using the GA. Presented results prove FA superiority and powerfulness in solving non-linear dynamic model of cultivation processes. 164 Roeva O. and Trenkova T..
Environmental Earth Sciences
In 2019 the Studena reservoir, the only water supply source for the town of Pernik in Bulgaria, a... more In 2019 the Studena reservoir, the only water supply source for the town of Pernik in Bulgaria, accumulated less than half of its normal annual inflow. This factor, together with an inadequate and delayed response by the water resource managers caused a severe water supply crisis in the fall and winter of that year. As this situation was unprecedented, investigations were undertaken to determine the cause of the low inflow to the reservoir using the model CLM3 and available climatic and spatial data, and data that were collected in the watershed for the reservoir. The study was conducted by simulating the hydrological processes that take place in the watershed, and the monthly inflows to the reservoir for the period 2017–2019. It was found that hydrological parameters produced in the calibrated model were similar to those measured in the field and by another model. The achieved agreement was considered to be satisfactory given the complexity of their nature and assessment methods. The result of the study convincingly confirmed that the main reason for the poor inflow to the reservoir in 2019 was the low precipitation in this year and, above all, the scarce snowfall in the winter months. Although the total annual precipitation falling in the region during the period 2017–2019 has not changed significantly, but the seasonal distribution of precipitation has changed. In particular, the amount of precipitation that falls in snowfalls has declined and reached a minimum in 2019. These decreases are due to the increase in the average air temperature of 1 °C which causes the observed decreases in the runoff.
AIP Conference Proceedings, 2019
The unsaturated soil zone is a link between the surface and the groundwater environment. Its comp... more The unsaturated soil zone is a link between the surface and the groundwater environment. Its comprehensive physical representation, adopted by the Community Land Model (CLM), follows the integrated interaction between the soil matrix, plant roots and wetness dynamics. Land Surface Models (in the case CLM) are well developed tools accounting for: water and energy fluxes input from the atmosphere, energy conduction, water infiltration, further downward penetration throught the soil zone during precipitation and the upward evapotranspiration flow during dry conditions. The net gravitational water flow forms the groundwater recharge. The paper presents the application of the CLM model for groundwater recharge calculation for the Bulgarian territory. Additionally, the influence of the assumed in the model length of time discretization of the atmospheric forcings approximation on the accuracy of the results is studied. Available field data are used for comparison analyses.The unsaturated soil zone is a link between the surface and the groundwater environment. Its comprehensive physical representation, adopted by the Community Land Model (CLM), follows the integrated interaction between the soil matrix, plant roots and wetness dynamics. Land Surface Models (in the case CLM) are well developed tools accounting for: water and energy fluxes input from the atmosphere, energy conduction, water infiltration, further downward penetration throught the soil zone during precipitation and the upward evapotranspiration flow during dry conditions. The net gravitational water flow forms the groundwater recharge. The paper presents the application of the CLM model for groundwater recharge calculation for the Bulgarian territory. Additionally, the influence of the assumed in the model length of time discretization of the atmospheric forcings approximation on the accuracy of the results is studied. Available field data are used for comparison analyses.
AIP Conference Proceedings, 2019
Applied Ecology and Environmental Research
The paper discusses the impact of winter seasons climate change on crop yields in the South Centr... more The paper discusses the impact of winter seasons climate change on crop yields in the South Central Region of Bulgaria. Twenty-two years long field observations show a progressive increase in air temperature and a decrease in snow cover in the winter seasons. The reduction of snow and the air temperature rise are supposed to lead to reduction of water availability in the spring for the winter crops and respectively to lowering their yield. By compiling observed climatic data and those obtained through a spatially distributed climatic model for the region area analysed is the relationship between these climatic parameters and the respective harvest of the winter crops for the last 5 winter seasons. The observed in the analysed period winter crops yield does not show distinctly the supposed dependence on the decrease of the snowfall amount and snow cover residence time. The yields of the last winter season 2019/2020 with the least snow cover and 2 o C higher air temperature exceeded those of all other seasons. This effect is explained with the favourable combination of the high air temperature with the amount and monthly distribution of the precipitation in the season.
NATO Science for Peace and Security Series C: Environmental Security, 2009
Natural hazards and flood events are part of nature. In most cases, floods are caused by climatol... more Natural hazards and flood events are part of nature. In most cases, floods are caused by climatological phenomena, which are out of human control. The scale and frequency of floods are likely to increase in the future as a result of climate change, inappropriate river management and construction in flood risk areas. There has been a marked increase in vulnerability due to the number of people and economic assets located in flood risk zones. Two natural disasters such as drought and flood have effected on different parts of the earth as a result of increasing human's interference on global climate. In the recent years, our country was a witness in occurrence of floods and severe droughts, which has caused destruction of agricultural lands. The process of the delimitation of the endangered agricultural areas is a priority task for the Bulgarian scientists and the Water authorities. A research of the river basin of Mesta concerning such flood issues has been carried out. Hydrological analyses were made in order to get the probability of the maximum runoff. The obtained results were considered in different scenarios of flood events (water level or depth, flood extends), meeting the requirements of the European Union (EU) Flood Risk Management Directive. The presented research is a part of a project for young scientists about determination of the agricultural areas endangered by floods in the river Mesta watershed.
MATEC Web of Conferences, 2018
Estimating groundwater recharge is an important part of the water resources evaluation. In spite ... more Estimating groundwater recharge is an important part of the water resources evaluation. In spite of the numerous existing methods it continues to be not easy value to quantify. This is due to its dependence on many meteorological, hydrogeological, soil type and cover conditions and the impossibility for direct measurement. Employment of hydrological models in fact directly calculates the influence of the above cited natural factors. The Community Land Model (CLM3) being loaded with all land featuring data in global scale, including an adequate soil filtration process simulation by the Richards equation, together with the possibility for input of NCEP/NCAR Reanalyses database, featuring the meteorological effect, gives an opportunity to avoid to great extent the difficulties in groundwater (GW) recharge estimation. The paper presents the results from an experiment concerning GW recharge monthly estimation during 2013, worked out for the Kamchia river watershed in Bulgaria. The comput...
The advance in the web mapping technologies enabled the generation and use of vast amount of spat... more The advance in the web mapping technologies enabled the generation and use of vast amount of spatial data. First and foremost, challenge is the extraction of appropriate information from the excessive data overload. In this respect the needs of web-based GIS applications for fast and easy dissemination, display and sharing of spatial information are constantly growing. The work investigates some geovisualization techniques for user friendly data representation. A framework containing different data types is elaborated related to the utilization of spatial datasets for Yantra River Basin area. The prototype is developed to serve as a data-viewer for various users. The goal is to provide a comprehensive visualization tool for gaining better understanding from the available spatial data for the case study area. The application enables users to view, natural resources information for specific needs. The approach integrates only open source technologies for the development of the web-bas...
MATEC Web of Conferences, 2018
Estimating groundwater recharge is an important part of the water resources evaluation. In spite ... more Estimating groundwater recharge is an important part of the water resources evaluation. In spite of the numerous existing methods it continues to be not easy value to quantify. This is due to its dependence on many meteorological, hydrogeological, soil type and cover conditions and the impossibility for direct measurement. Employment of hydrological models in fact directly calculates the influence of the above cited natural factors. The Community Land Model (CLM3) being loaded with all land featuring data in global scale, including an adequate soil filtration process simulation by the Richards equation, together with the possibility for input of NCEP/NCAR Reanalyses database, featuring the meteorological effect, gives an opportunity to avoid to great extent the difficulties in groundwater (GW) recharge estimation. The paper presents the results from an experiment concerning GW recharge monthly estimation during 2013, worked out for the Kamchia river watershed in Bulgaria. The computed monthly and annual values are presented on GIS maps and are compared with existing assessments made by other methods. It is proved the good approach and the applicability of the method.
Water resources scheme, simulation model and GIS for the transboundary river basin of Struma have... more Water resources scheme, simulation model and GIS for the transboundary river basin of Struma have been developed as a part of the River Basin Management Plans (RBMP). The transboundary character of the river basin requires integrated water resources management. All considerable water resources and hydraulic relations between the water users and the environment are taken into consideration for the graphical scheme. The programme SIMYL has been applied and the functioning of the water resources system has been analyzed in different variants for water consumption and water resources. The calculated disturbance of the run-off at different stations in the river basin was given as an assessment of the anthropogenic pressure. Critical sections have been determined in accordance with the Water Frame Directive (WFD). The possible decisions of the basic problems of the river basin are analyzed in order to assist in the decision making process of integrated water resources management in the We...
ifigenia.org
In this work a modified multi-population genetic algorithm (MPGA) without the performance of the ... more In this work a modified multi-population genetic algorithm (MPGA) without the performance of the mutation operator is proposed. The idea is to reduce the convergence time and therefore to increase the identification procedure effectiveness for on-line application of the algorithm. Modified MPGA, classical multipopulation GA and two other modifications are tested for parameter identification problem of an E. coli non-linear fed-batch cultivation model. The contribution of each modification measure to the performance improvement is demonstrated. The obtained results show that the highest accuracy for parameter identification of the considered model is achieved with the multipopulation GA with Modification 1. The best calculation time is shown by the multipopulation GA without mutation. X S A J J J J min = + + →