Kostas Kalabokidis - Academia.edu (original) (raw)
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Papers by Kostas Kalabokidis
Computers & Geosciences, 2009
European Journal of Forest Research, 2012
The focus of our study is to assess fire risk zones using historical wildland fire ignition obser... more The focus of our study is to assess fire risk zones using historical wildland fire ignition observations recorded between 1985 and 2004. Kernel density estimation, a non parametric statistical method for estimating probability densities, has been widely used for home range estimation in wildlife ecology. It has the advantage of directly producing density estimates that are not influenced by grid
Advances in Engineering Software, 2015
ABSTRACT This paper proposes a novel training algorithm for radial basis function neural networks... more ABSTRACT This paper proposes a novel training algorithm for radial basis function neural networks based on fuzzy clustering and particle swarm optimization. So far, fuzzy clustering has proven to be a very efficient tool in designing such kind of networks. The motivation of the current work is to quantify the exact effect of fuzzy cluster analysis on the network's performance and use it in order to substantially improve this per-formance. There are two key theoretical findings resulting from the present work. First, it is analytically proved that when the standard fuzzy c-means algorithm is used to generate the input space fuzzy parti-tion, the main effect this partition imposes to the network's square error (i.e. performance index) can be written down in terms of a distortion function that measures the ability of the partition to recreate the original data. Second, using the aforementioned distortion function, an upper bound of the network's square error can be constructed. Then, the particle swarm optimization (PSO) is put in place to minimize the above upper bound and determine the network's parameters. To further improve the accuracy, the basis function widths and the connection weights are fine-tuned by employing a steepest descent approach. The main experimental findings are: (a) the implementation of the PSO obtains a significant reduction of the square error while exhibiting a smooth dynamic behavior, (b) although the steepest des-cent further decreases the error it finally obtains smaller reduction rates, meaning that the strongest impact on the error reduction is provided by the PSO, and (c) the improved performance of the proposed network is demonstrated through an extensive comparison with other related methods using a 10-fold cross-validation analysis.
Advances in forest fire research, 2014
Restoration of Mediterranean-type forest ecosystems is of great importance and a main environment... more Restoration of Mediterranean-type forest ecosystems is of great importance and a main environmental issue in Greece and other countries of the Mediterranean basin as well. For the effective implementation of proper restoration practices, a thorough knowledge is required as regards post-fire regeneration processes, namely changes that occur in the vegetation composition and the evolution of ecosystem resilience rate, after one or more fire incidents. The research work presented in the paper, took place at the National Park of Sounio (Greece), where an intensive forest land survey was performed. Forest-ecosystem resilience and vegetation composition was studied under various post-fire regimes by the use of Remote Sensing and GIS techniques. For that purpose, Landsat (TM and ETM+) satellite images spanning a 20-year period were used for the calculation of NDVI time-series. Classification maps depicting the pre- and post-fire situation were also considered. Results showed that for the s...
Natural Resource Modeling, 2008
Journal of Maps, 2014
ABSTRACT
Journal of Environmental Policy & Planning, 2011
... b , Kostas Kalabokidis c & Theodoros Iosifides c pages 349-371. ... Kalabokidis, KD a... more ... b , Kostas Kalabokidis c & Theodoros Iosifides c pages 349-371. ... Kalabokidis, KD and Stamou, N. Analysis and planning for forest fire management in the Aegean. Proceedings of the 7th National Forestry Conference . October 11–13 1995 , Karditsa, Greece. pp.558–567. ...
International Journal of Wildland Fire, 2007
International Journal of Remote Sensing, 2013
ABSTRACT This study aims at quantifying and mapping fire-related characteristics of forest struct... more ABSTRACT This study aims at quantifying and mapping fire-related characteristics of forest structure through field inventories, statistics, remote sensing, and geographical information systems in the island of Lesvos, northeast Aegean Sea, Greece. Simulation of fire behaviour requires forest biomass inputs that describe surface fuel types/models along with canopy fuel properties, such as canopy cover, stand height, crown base height, and crown bulk density, to accurately predict surface and crown fire spread and spotting potential. Forest canopy characteristics and other vegetation attributes were sampled and derived in over 100 field plots, the majority of which were located in coastal pine forest stands. Regression models involving four dependent forest stand variables (stand height, canopy cover, crown base height, and crown bulk density) were developed using generalized additive models. The values of adjusted R 2 were 0.72 for stand height, 0.68 for canopy cover, 0.51 for crown base height, and 0.33 for crown bulk density. These regression models were used to create forest fuel characteristics layers, which can be used as inputs to fire management applications and state-of-the-art landscape-scale fire behaviour models.
European Journal of Forest Research, 2012
Environmental Science & Policy, 2008
Computers & Geosciences, 2011
Proceedings of the …, 2002
ABSTRACT: Fire, weather and vegetation patterns are key elements of the natural environment viewe... more ABSTRACT: Fire, weather and vegetation patterns are key elements of the natural environment viewed in human perspective. Knowledge of the causes that configure the structure and spatial distribution of vegetation is the cornerstone in sustainable development, especially in ...
Area, 2007
This paper focuses on spatial distribution of long-term fire patterns versus physical and anthrop... more This paper focuses on spatial distribution of long-term fire patterns versus physical and anthropogenic elements of the environment that determine wildfire dynamics in Greece. Logistic regression and correspondence analysis were applied in a spatial database that had been ...
Human Ecology …, 2005
This paper compares Greek and American social experi-ence of wildfire management. Regional compar... more This paper compares Greek and American social experi-ence of wildfire management. Regional comparison of the two countries' experience with wildfire reveals a common thread of experience and management regimes. Efforts to control the risk of fire damage over time have ...
European Journal of Forest Research, 2011
Computers & Geosciences, 2009
European Journal of Forest Research, 2012
The focus of our study is to assess fire risk zones using historical wildland fire ignition obser... more The focus of our study is to assess fire risk zones using historical wildland fire ignition observations recorded between 1985 and 2004. Kernel density estimation, a non parametric statistical method for estimating probability densities, has been widely used for home range estimation in wildlife ecology. It has the advantage of directly producing density estimates that are not influenced by grid
Advances in Engineering Software, 2015
ABSTRACT This paper proposes a novel training algorithm for radial basis function neural networks... more ABSTRACT This paper proposes a novel training algorithm for radial basis function neural networks based on fuzzy clustering and particle swarm optimization. So far, fuzzy clustering has proven to be a very efficient tool in designing such kind of networks. The motivation of the current work is to quantify the exact effect of fuzzy cluster analysis on the network's performance and use it in order to substantially improve this per-formance. There are two key theoretical findings resulting from the present work. First, it is analytically proved that when the standard fuzzy c-means algorithm is used to generate the input space fuzzy parti-tion, the main effect this partition imposes to the network's square error (i.e. performance index) can be written down in terms of a distortion function that measures the ability of the partition to recreate the original data. Second, using the aforementioned distortion function, an upper bound of the network's square error can be constructed. Then, the particle swarm optimization (PSO) is put in place to minimize the above upper bound and determine the network's parameters. To further improve the accuracy, the basis function widths and the connection weights are fine-tuned by employing a steepest descent approach. The main experimental findings are: (a) the implementation of the PSO obtains a significant reduction of the square error while exhibiting a smooth dynamic behavior, (b) although the steepest des-cent further decreases the error it finally obtains smaller reduction rates, meaning that the strongest impact on the error reduction is provided by the PSO, and (c) the improved performance of the proposed network is demonstrated through an extensive comparison with other related methods using a 10-fold cross-validation analysis.
Advances in forest fire research, 2014
Restoration of Mediterranean-type forest ecosystems is of great importance and a main environment... more Restoration of Mediterranean-type forest ecosystems is of great importance and a main environmental issue in Greece and other countries of the Mediterranean basin as well. For the effective implementation of proper restoration practices, a thorough knowledge is required as regards post-fire regeneration processes, namely changes that occur in the vegetation composition and the evolution of ecosystem resilience rate, after one or more fire incidents. The research work presented in the paper, took place at the National Park of Sounio (Greece), where an intensive forest land survey was performed. Forest-ecosystem resilience and vegetation composition was studied under various post-fire regimes by the use of Remote Sensing and GIS techniques. For that purpose, Landsat (TM and ETM+) satellite images spanning a 20-year period were used for the calculation of NDVI time-series. Classification maps depicting the pre- and post-fire situation were also considered. Results showed that for the s...
Natural Resource Modeling, 2008
Journal of Maps, 2014
ABSTRACT
Journal of Environmental Policy & Planning, 2011
... b , Kostas Kalabokidis c & Theodoros Iosifides c pages 349-371. ... Kalabokidis, KD a... more ... b , Kostas Kalabokidis c & Theodoros Iosifides c pages 349-371. ... Kalabokidis, KD and Stamou, N. Analysis and planning for forest fire management in the Aegean. Proceedings of the 7th National Forestry Conference . October 11–13 1995 , Karditsa, Greece. pp.558–567. ...
International Journal of Wildland Fire, 2007
International Journal of Remote Sensing, 2013
ABSTRACT This study aims at quantifying and mapping fire-related characteristics of forest struct... more ABSTRACT This study aims at quantifying and mapping fire-related characteristics of forest structure through field inventories, statistics, remote sensing, and geographical information systems in the island of Lesvos, northeast Aegean Sea, Greece. Simulation of fire behaviour requires forest biomass inputs that describe surface fuel types/models along with canopy fuel properties, such as canopy cover, stand height, crown base height, and crown bulk density, to accurately predict surface and crown fire spread and spotting potential. Forest canopy characteristics and other vegetation attributes were sampled and derived in over 100 field plots, the majority of which were located in coastal pine forest stands. Regression models involving four dependent forest stand variables (stand height, canopy cover, crown base height, and crown bulk density) were developed using generalized additive models. The values of adjusted R 2 were 0.72 for stand height, 0.68 for canopy cover, 0.51 for crown base height, and 0.33 for crown bulk density. These regression models were used to create forest fuel characteristics layers, which can be used as inputs to fire management applications and state-of-the-art landscape-scale fire behaviour models.
European Journal of Forest Research, 2012
Environmental Science & Policy, 2008
Computers & Geosciences, 2011
Proceedings of the …, 2002
ABSTRACT: Fire, weather and vegetation patterns are key elements of the natural environment viewe... more ABSTRACT: Fire, weather and vegetation patterns are key elements of the natural environment viewed in human perspective. Knowledge of the causes that configure the structure and spatial distribution of vegetation is the cornerstone in sustainable development, especially in ...
Area, 2007
This paper focuses on spatial distribution of long-term fire patterns versus physical and anthrop... more This paper focuses on spatial distribution of long-term fire patterns versus physical and anthropogenic elements of the environment that determine wildfire dynamics in Greece. Logistic regression and correspondence analysis were applied in a spatial database that had been ...
Human Ecology …, 2005
This paper compares Greek and American social experi-ence of wildfire management. Regional compar... more This paper compares Greek and American social experi-ence of wildfire management. Regional comparison of the two countries' experience with wildfire reveals a common thread of experience and management regimes. Efforts to control the risk of fire damage over time have ...
European Journal of Forest Research, 2011