The model is based on spline-approximation of the measured Te in 5-dimensional space comprised of... more The model is based on spline-approximation of the measured Te in 5-dimensional space comprised of solar activity (F10.7), month of the year, local time, longitude and geomagnetic latitude. Each axis is divided into subintervals delimited by a number of nodes, which assure the error to be smallest. During the lifetime of Hinotori satellite, F10.7 has varied between 140 and 230, so the model is constrained to this solar activity range. The geomagnetic latitude range is limited to +/-42° due to the low inclination orbit of the satellite. The model error has been evaluated using the whole database, containing 17 months of data (4.2x105 measured values). The standard (mean square root) deviation of the data from the model is found to be around 14%. The model predictions are compared with measured data during 5 geomagnetic storms. Assuming that Te model reflects the average geomagnetic conditions, the systematic deviations of measured Te from the model ones during some strong geomagnetic ...
The heat and the particle loads on the divertor plates from the plasma in the scrape-off layer (S... more The heat and the particle loads on the divertor plates from the plasma in the scrape-off layer (SOL) are studied in edge localized modes (ELM) with high frequency. For this purpose we have per-formed computer experiments with self-consistent simulation of the neutral particles in the SOL of toka-maks with deuterium plasma assuming different regimes (instant cold and permanent hot gass puffing).
The topside ionospheric scale height (TISH) and the O+-H+ transition height (TH) are key ionosphe... more The topside ionospheric scale height (TISH) and the O+-H+ transition height (TH) are key ionospheric parameters which are of special interest when studying and modelling the plasma composition and dynamics. Recently, new TISH and TH empirical models have been developed. The database for these models has been built upon thousands of TISH and TH values deduced from electron profiles obtained via topside sounding measurements. For validation purposes, it would be interesting to compare calculations of the ionospheric scale/transition heights as calculated by the topside-sounder TISH/TH models and other well-known models - NeQuick and Parameterized Ionospheric Model (PIM). Electron density profiles, in the altitude range 200-2000 km, are obtained from the NeQuick and PIM models for a grid of input parameters, such as month, local time, geomagnetic latitude, F10.7 solar flux. The topside scale height and O+-H+ transition height values are extracted from each of these profiles in the same...
A method is presented for reconstructing the vertical ionospheric profile utilizing multi-instrum... more A method is presented for reconstructing the vertical ionospheric profile utilizing multi-instrument observations. High-accuracy, ground-based digital ionosonde measurements are used for directly obtaining the bottom-side part (below the ionospheric peak height) of the electron density profile. Simultaneously-measured over-satellite electron content (OSEC) data from low Earth orbiting (LEO) satellites can be used for the determination of the top-side ionospheric scale height. The top-side ion density distribution is permitted to take one of several forms (profilers): Exponential, Chapman, or Epstein; the choice depending on the local time and the sub-ionospheric point’s location. The ion scale heights are calculated by solving a system of equations that arise from the incorporation of the abovementioned ionospheric profilers into formulae describing ionospheric conditions/characteristics such as plasma quasi-neutrality and ion transition level. Once the topside scale heights are det...
This report presents the final results of the project "An improved model for operational spe... more This report presents the final results of the project "An improved model for operational specification of the electron density structure up to geosynchronous heights," with the following main objectives: a) To upgrade the Topside Sounder Model Profiler (TSMP) and the TSMP-assisted Digisonde (TaD) model; b) To validate the results using ISR and topside electron density profiles, GNSS TEC and partial TEC parameters; c) To specify added-value products based on the TaD functional capabilities; d) To implement the TaD model on-line ingesting auto-scaled ionospheric parameters from Athens Digisonde; e) To develop a prototype web service demonstrating the functionality of TaD to operate online using as input auto-scaled ionospheric parameters; and f) To demonstrate some of the indicative value-added products derived from the TaD outputs.
ABSTRACT Ant colony optimization (ACO) is a stochastic search method that mimic the social behavi... more ABSTRACT Ant colony optimization (ACO) is a stochastic search method that mimic the social behavior of real ants colonies, which manage to establish the shortest rout to feeding sources and back. Such algorithms have been developed to arrive at near-optimal solutions to large-scale optimization problems, for which traditional mathematical techniques may fail. On this paper is proposed an ant algorithm with semi-random start. Several start strategies are prepared at the basis of the start nodes estimation. There are several parameters which manage the starting strategies. In this work we focus on influence on the quality of the achieved solutions of the parameters which shows the percentage of the solutions classified as good and as bad respectively. This new technique is tested on multiple knapsack problem (MKP).
Proceedings of the International Multiconference on Computer Science and Information Technology, 2010
Ant Colony Optimization (ACO) is a stochastic search method that mimics the social behavior of re... more Ant Colony Optimization (ACO) is a stochastic search method that mimics the social behavior of real ants colonies, which manage to establish the shortest route to feeding sources and back. Such algorithms have been developed to arrive at near-optimal solutions to large-scale optimization problems, for which traditional mathematical techniques may fail. On this paper semi-random start is applied. A new
Ant Colony Optimization is a stochastic search method that mimic the social behavior of real ants... more Ant Colony Optimization is a stochastic search method that mimic the social behavior of real ants colonies, which manage to establish the shortest routs to feeding sources and back. Such algorithms have been developed to arrive at near-optimum solutions to large-scale optimization problems, for which traditional mathematical techniques may fail. In this paper on each iteration estimations of the start
Ant Colony Optimization (ACO) has been used successfully to solve hard combinatorial optimization... more Ant Colony Optimization (ACO) has been used successfully to solve hard combinatorial optimization problems. This metaheuristic method is inspired by the foraging behavior of ant colonies, which manage to establish the shortest routes to feeding sources and back. On this work we use estimation of start nodes with respect to the quality of the solution. Various start strategies are offered.
This work examines major peculiarities in the inter-annual climatology of the so-called "wav... more This work examines major peculiarities in the inter-annual climatology of the so-called "wave-number four" (WN4) structures in the topside ionosphere at mid and low latitudes. For the period of declining solar activity 2002-2005, densities of major H+ and O+ ions as well as ion temperature data obtained at ~840km altitude by "Special Sensor-Ion, Electron and Scintillations" (SSIES) instrument onboard DMSP-F13
The effect of charged particle recombination is investigated per- forming particle in cell (PIC) ... more The effect of charged particle recombination is investigated per- forming particle in cell (PIC) simulation of plasma in tokamak devices. For the simulation of particle collisions is used an appropriate method to account for frequencies spread in wide range of magnitude. The method was tested simulat- ing steady state plasma in the scrape off layer (SOL). A constant density profile of deuterium atoms is assumed with sharp peaks in divertor region. The simulation results show decreasing frequency of recombination near the plates of divertor where the ionization is dominating due to the big concentratio n of deuterium atoms. The recombination processes become more frequent deep in the SOL where the density of neutral particles is rather low.
Intuitionistic Fuzzy Estimations of the Ant Colony Optimization Stefka Fidanova, Krasimir Atanaso... more Intuitionistic Fuzzy Estimations of the Ant Colony Optimization Stefka Fidanova, Krasimir Atanasov, Pencho Marinov 1 Introduction Combinatorial optimization is a ... Update-pheromone-trails; end while Figure 1: Pseudocode for ACO The pheromone trail update rule is given by: τi ...
The model is based on spline-approximation of the measured Te in 5-dimensional space comprised of... more The model is based on spline-approximation of the measured Te in 5-dimensional space comprised of solar activity (F10.7), month of the year, local time, longitude and geomagnetic latitude. Each axis is divided into subintervals delimited by a number of nodes, which assure the error to be smallest. During the lifetime of Hinotori satellite, F10.7 has varied between 140 and 230, so the model is constrained to this solar activity range. The geomagnetic latitude range is limited to +/-42° due to the low inclination orbit of the satellite. The model error has been evaluated using the whole database, containing 17 months of data (4.2x105 measured values). The standard (mean square root) deviation of the data from the model is found to be around 14%. The model predictions are compared with measured data during 5 geomagnetic storms. Assuming that Te model reflects the average geomagnetic conditions, the systematic deviations of measured Te from the model ones during some strong geomagnetic ...
The heat and the particle loads on the divertor plates from the plasma in the scrape-off layer (S... more The heat and the particle loads on the divertor plates from the plasma in the scrape-off layer (SOL) are studied in edge localized modes (ELM) with high frequency. For this purpose we have per-formed computer experiments with self-consistent simulation of the neutral particles in the SOL of toka-maks with deuterium plasma assuming different regimes (instant cold and permanent hot gass puffing).
The topside ionospheric scale height (TISH) and the O+-H+ transition height (TH) are key ionosphe... more The topside ionospheric scale height (TISH) and the O+-H+ transition height (TH) are key ionospheric parameters which are of special interest when studying and modelling the plasma composition and dynamics. Recently, new TISH and TH empirical models have been developed. The database for these models has been built upon thousands of TISH and TH values deduced from electron profiles obtained via topside sounding measurements. For validation purposes, it would be interesting to compare calculations of the ionospheric scale/transition heights as calculated by the topside-sounder TISH/TH models and other well-known models - NeQuick and Parameterized Ionospheric Model (PIM). Electron density profiles, in the altitude range 200-2000 km, are obtained from the NeQuick and PIM models for a grid of input parameters, such as month, local time, geomagnetic latitude, F10.7 solar flux. The topside scale height and O+-H+ transition height values are extracted from each of these profiles in the same...
A method is presented for reconstructing the vertical ionospheric profile utilizing multi-instrum... more A method is presented for reconstructing the vertical ionospheric profile utilizing multi-instrument observations. High-accuracy, ground-based digital ionosonde measurements are used for directly obtaining the bottom-side part (below the ionospheric peak height) of the electron density profile. Simultaneously-measured over-satellite electron content (OSEC) data from low Earth orbiting (LEO) satellites can be used for the determination of the top-side ionospheric scale height. The top-side ion density distribution is permitted to take one of several forms (profilers): Exponential, Chapman, or Epstein; the choice depending on the local time and the sub-ionospheric point’s location. The ion scale heights are calculated by solving a system of equations that arise from the incorporation of the abovementioned ionospheric profilers into formulae describing ionospheric conditions/characteristics such as plasma quasi-neutrality and ion transition level. Once the topside scale heights are det...
This report presents the final results of the project "An improved model for operational spe... more This report presents the final results of the project "An improved model for operational specification of the electron density structure up to geosynchronous heights," with the following main objectives: a) To upgrade the Topside Sounder Model Profiler (TSMP) and the TSMP-assisted Digisonde (TaD) model; b) To validate the results using ISR and topside electron density profiles, GNSS TEC and partial TEC parameters; c) To specify added-value products based on the TaD functional capabilities; d) To implement the TaD model on-line ingesting auto-scaled ionospheric parameters from Athens Digisonde; e) To develop a prototype web service demonstrating the functionality of TaD to operate online using as input auto-scaled ionospheric parameters; and f) To demonstrate some of the indicative value-added products derived from the TaD outputs.
ABSTRACT Ant colony optimization (ACO) is a stochastic search method that mimic the social behavi... more ABSTRACT Ant colony optimization (ACO) is a stochastic search method that mimic the social behavior of real ants colonies, which manage to establish the shortest rout to feeding sources and back. Such algorithms have been developed to arrive at near-optimal solutions to large-scale optimization problems, for which traditional mathematical techniques may fail. On this paper is proposed an ant algorithm with semi-random start. Several start strategies are prepared at the basis of the start nodes estimation. There are several parameters which manage the starting strategies. In this work we focus on influence on the quality of the achieved solutions of the parameters which shows the percentage of the solutions classified as good and as bad respectively. This new technique is tested on multiple knapsack problem (MKP).
Proceedings of the International Multiconference on Computer Science and Information Technology, 2010
Ant Colony Optimization (ACO) is a stochastic search method that mimics the social behavior of re... more Ant Colony Optimization (ACO) is a stochastic search method that mimics the social behavior of real ants colonies, which manage to establish the shortest route to feeding sources and back. Such algorithms have been developed to arrive at near-optimal solutions to large-scale optimization problems, for which traditional mathematical techniques may fail. On this paper semi-random start is applied. A new
Ant Colony Optimization is a stochastic search method that mimic the social behavior of real ants... more Ant Colony Optimization is a stochastic search method that mimic the social behavior of real ants colonies, which manage to establish the shortest routs to feeding sources and back. Such algorithms have been developed to arrive at near-optimum solutions to large-scale optimization problems, for which traditional mathematical techniques may fail. In this paper on each iteration estimations of the start
Ant Colony Optimization (ACO) has been used successfully to solve hard combinatorial optimization... more Ant Colony Optimization (ACO) has been used successfully to solve hard combinatorial optimization problems. This metaheuristic method is inspired by the foraging behavior of ant colonies, which manage to establish the shortest routes to feeding sources and back. On this work we use estimation of start nodes with respect to the quality of the solution. Various start strategies are offered.
This work examines major peculiarities in the inter-annual climatology of the so-called "wav... more This work examines major peculiarities in the inter-annual climatology of the so-called "wave-number four" (WN4) structures in the topside ionosphere at mid and low latitudes. For the period of declining solar activity 2002-2005, densities of major H+ and O+ ions as well as ion temperature data obtained at ~840km altitude by "Special Sensor-Ion, Electron and Scintillations" (SSIES) instrument onboard DMSP-F13
The effect of charged particle recombination is investigated per- forming particle in cell (PIC) ... more The effect of charged particle recombination is investigated per- forming particle in cell (PIC) simulation of plasma in tokamak devices. For the simulation of particle collisions is used an appropriate method to account for frequencies spread in wide range of magnitude. The method was tested simulat- ing steady state plasma in the scrape off layer (SOL). A constant density profile of deuterium atoms is assumed with sharp peaks in divertor region. The simulation results show decreasing frequency of recombination near the plates of divertor where the ionization is dominating due to the big concentratio n of deuterium atoms. The recombination processes become more frequent deep in the SOL where the density of neutral particles is rather low.
Intuitionistic Fuzzy Estimations of the Ant Colony Optimization Stefka Fidanova, Krasimir Atanaso... more Intuitionistic Fuzzy Estimations of the Ant Colony Optimization Stefka Fidanova, Krasimir Atanasov, Pencho Marinov 1 Introduction Combinatorial optimization is a ... Update-pheromone-trails; end while Figure 1: Pseudocode for ACO The pheromone trail update rule is given by: τi ...
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