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Thuy Ngo

Korea University, Republic of Korea, Department of Civil, Environmental and Architectural Engineering, Graduate Student

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Thi Thuy Ngo received her BS degree in Hydrology and Environment in 2008 from Water Resources University, Hanoi, Vietnam. In 2009, she achieved master scholarship from DAAD for TERMA-VN program in Hanoi, Vietnam. From 2008 to 2013, she was a researcher in Vietnam Institute of Meteorology Hydrology and Climate change (IMHEN). She now is PhD student in Korea University, Seoul, Korea. Her interests are urban drainage system operation, optimization and water resources management.
Supervisors: Joong Hoon Kim and Lars Ribber

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Papers by Thuy Ngo

Flood vulnerability assessment at the local scale using remote sensing and GIS techniques: a case study in Da Nang City, Vietnam

Journal of Water and Climate Change

This paper has developed a cost-efficient framework for flood vulnerability assessment at a local... more This paper has developed a cost-efficient framework for flood vulnerability assessment at a local scale using a multi-parametric approach integrated with the Open Source Geographical Information System (GIS) and Open Remote Sensing data. The study focuses on generating a set of criteria considering three dimensions of flood vulnerability: exposure, sensitivity, and adaptive capacity (AC) on an index-based approach. These indicators were decided based on a robust analysis considering the physical and socio-economic conditions of the study area. The flood exposure was generated from the geomorphological and hydrological parameters integrated with the flood water depth, the distance to river channels, and the Modified Normalized Difference Water Index. The flood sensitivity was determined by the aggregation of local income, land use, poverty index, population density, and other parameters reflecting the socio-economic condition. The AC has been evaluated based on the Normalized Differe...

Pre-disaster assessment of flood risk for mid Central Vietnam

International Journal of Disaster Resilience in the Built Environment, 2021

Purpose Nowadays, under climate change contexts, natural disasters are becoming stronger in inten... more Purpose Nowadays, under climate change contexts, natural disasters are becoming stronger in intensity and probability. The impacts of natural disasters on people and the environment are also getting worse. The purpose of this study was conducted to provide a method of assessing disaster risks, in particular, floods for human life in Mid Central Vietnam. Design/methodology/approach The pre-disaster assessment method was used based on the analysis of hazard factors (Hazard-H), exposure to hazards (Exposure-E) and vulnerability (Vulnerability-V). Findings Flood disaster risks in the area are assessed and displayed on spatial maps. The districts in coastal plains of Quang Ngai and Thua Thien Hue provinces have the highest levels of risk. These assessments will play an important role in supporting flood prevention and mitigation in the region. Originality/value According to the authors, this is the first study assessing the flood risk in Vietnam on the pre-disaster perspective. The asses...

Water Scarcity in Vietnam: a Point of View on Virtual Water Perspective

Water Resources Management, 2018

This paper quantifies water consumption of Vietnam in agricultural products on virtual water pers... more This paper quantifies water consumption of Vietnam in agricultural products on virtual water perspective. The calculation of water footprint and virtual water in four major agricultural crops is first implemented for seven regions of the country. The domestic and international trades of virtual water are subsequently investigated to demonstrate the commodity and virtual water flows among regions. The analysis reveals that Mekong River Delta is an important exporter of virtual water in rice product for both domestic and international trades while Central Highland is the main virtual exporter in coffee. The paper also proposes a new water stress index such that it considers both direct and indirect water use given transboundary water resources. The proposed water stress index indicates the actual water scarcity in Vietnam in which the water-rich regions i.e. Red River Delta and Mekong River Delta are in severe water stress.

Decentralization-based optimization of detention reservoir systems for flood reduction in urban drainage areas

Urban Water Journal, 2018

The paper introduces a decentralized approach to optimizing the flood reduction efficiency of mul... more The paper introduces a decentralized approach to optimizing the flood reduction efficiency of multiple detention reservoirs in urban areas. The flood reduction effects of a detention reservoir system were regionally assessed, and a new model was then created using an optimization technique which involved coupling extraordinary particle swarm optimization with a flood simulation engine, Storm Water Management Model, EPA-SWMM, to identify optimal outlet designs for a detention reservoir system. When applied to the To Lich drainage network (Hanoi, Vietnam) the proposed method outperformed the present design, reducing flooding under the design flood event. The performance of the approach was verified by comparing it with the overall objective function of total flooded volume for different design floods. The better performance of the decentralized optimization approach described here, in terms of local and regional flood management, illustrated its effectiveness for urban flooding reduction.

Linear System Theory-Based Optimization of Detention Basin’s Location and Size at Watershed Scale

Journal of Hydrologic Engineering, 2016

AbstractIn the context of urbanization and waterworks construction, detention basins located in u... more AbstractIn the context of urbanization and waterworks construction, detention basins located in upstream tributaries have become one of the most-effective technical solutions for downstream flood reduction. This technical note proposes a new optimal approach for determining the most-effective design combination of detention basins (in terms of their sizes and locations) in a watershed utilizing linear reservoir theory. The optimal detention basin is obtained by minimizing the deviation of downstream peak discharge from river capacity discharge. With the presence of a detention basin in an upstream river, the flood peak downstream decreases by 33%, corresponding to two scenarios of rainfall duration with a return period T=100 years. The storage volume estimation of the optimal detention reservoir proposed in the present paper demonstrates the high applicability of this optimization approach.

A cooperative particle swarm optimizer with stochastic movements for computationally expensive numerical optimization problems

Journal of Computational Science, 2016

Abstract Nature is the rich principal source for developing optimization algorithms. Metaheuristi... more Abstract Nature is the rich principal source for developing optimization algorithms. Metaheuristic algorithms can be classified with the emphasis on the source of inspiration into several categories such as biology, physics, and chemistry. The particle swarm optimization (PSO) is one of the most well-known bio-inspired optimization algorithms which mimics movement behavior of animal flocks especially bird and fish flocking. In standard PSO, velocity of each particle is influenced by the best individual and its best personal experience. This approach could make particles trap into the local optimums and miss opportunities of jumping to far better optimums than the currents and sometimes causes fast premature convergence. To overcome this issue, a new movement concept, so called extraordinariness particle swarm optimizer (EPSO) is proposed in this paper. The main contribution of this study is proposing extraordinary motion for particles in the PSO. Indeed, unlike predefined movement used in the PSO, particles in the EPSO can move toward a target which can be global best, local bests, or even the worst individual. The proposed improved PSO outperforms than the standard PSO and its variants for benchmarks such as CEC 2015 benchmarks. In addition, several constrained and engineering design problems have been tackled using the improved PSO and the optimization results have been compared with the standard PSO, variants of PSO, and other optimizers.

Robust Urban Drainage System: Development of a Novel Multiscenario-Based Design Approach

Journal of Water Resources Planning and Management, 2019

A traditional single-scenario design approach considers the most probable future scenario, which ... more A traditional single-scenario design approach considers the most probable future scenario, which is very risky and may result in high supplementary cost or overpayment (i.e., regret cost). An alternative involves simultaneously considering multiple scenarios. The present study proposes a novel two-phase multiscenario-based design approach to optimize the layout and hydraulic design (determining pipe sizes and manhole depths) of an urban sewer system. In the first phase, multiple individual scenarios are adopted to independently identify the optimal layout for each scenario and the requisite hydraulic design. The aim of the second phase involves determining robust solutions for the sewer layout and hydraulic design to minimize construction cost with a constraint on acceptable regret costs over multiple scenarios. The proposed two-phase optimization method is demonstrated with a hypothetical example of an urban drainage system. The results indicate that the proposed multiscenario optimization approach produces a robust sewer network solution that performs well and is cost-effective for different scenarios.

Optimization of Upstream Detention Reservoir Facilities for Downstream Flood Mitigation in Urban Areas

Water, 2016

A detention reservoir is one of the most effective engineered solutions for flood damage mitigati... more A detention reservoir is one of the most effective engineered solutions for flood damage mitigation in urban areas. Detention facilities are constructed to temporarily store storm water and then slowly drain when the peak period has passed. This delayed drainage may coincide with upstream floods and aggravate the flood risk downstream. Optimal operation and design are needed to improve the performance of detention reservoirs for flood reduction. This study couples hydrologic simulation software (EPA-SWMM) with an evolutional optimizer (extraordinary particle swarm optimization, EPSO) to minimize flood damage downstream while considering the inundation risk at the detention reservoir. The optimum design and operation are applied to an urban case study in Seoul, Korea, for historical severe flooding events and designed rainfall scenarios. The optimal facilities outperform the present facilities in terms of flood damage reduction both downstream and in the detention reservoir area. Specifically, the peak water level at the detention pond under optimal conditions is significantly smaller than that of the current conditions. The comparison of the total flooded volume in the whole watershed shows a dramatic reduction of 79% in a severe flooding event in 2010 and around 20% in 2011 and in 180 min designed rainfall scenarios.

The Extraordinary Particle Swarm Optimization and Its Application in Constrained Engineering Problems

Advances in Intelligent Systems and Computing

The particle swarm optimization (PSO) is a natural-inspire optimization algorithm mimicking the m... more The particle swarm optimization (PSO) is a natural-inspire optimization algorithm mimicking the movement behavior of animal flocks for food searching. Although the algorithm presents some advantages and widely application, however, there are several drawbacks such as trapping in local optima and immature convergence rate. To overcome these disadvantages, many improved versions of PSO have been proposed. One of the latest variants is the extraordinary particle swarm optimization (EPSO). The particles in the EPSO are assigned to move toward their own determined target through the search space. The applicability of EPSO is verified by several experiments in engineering optimization problems. The application results show the outperformance of the EPSO than the other PSO variants in terms of solution searching and as well as convergence rate.

Self-similarity characteristics in the organization of natural river networks on the basis of Shreve ’ s ordering scheme

Natural river networks exhibit interesting scaling laws representing their fractal features. One ... more Natural river networks exhibit interesting scaling laws representing their fractal features. One of the most widely-known laws is Horton’s law which illustrates log-linear characteristics between the stream order and geomorphological measures (the number of branches, length of branches, and drainage area). Horton’s law is based on Horton-Strahler ordering scheme. This ordering scheme apparently creates an omission in accounting of first-order segments which are primary collectors of rainfall within a basin. An alternative ordering scheme is Shreve’s ordering scheme. Nevertheless, most studies on river network organization thus far have been implemented on the basis of Horton-Strahler ordering scheme. In this study, we investigate how self-similarity characteristics of natural river networks emerge in the Shreve’s ordering framework. We investigate whether scaling principles similar with Horton’s and Hack’s laws appear in the Shreve’s framework. Our study on a Vietnamese river basin ...

Estimation of Pump Capacity in Detention Reservoir for Reducing Urban Inundation

An Efficient Algorithm Based on Neu ral Networks for Solving Differential Equations Arising in Engineering Applications

Numerical Solution of Boundary Value Problems Using Artificial Neural Networks and Harmony Search

Advances in Intelligent Systems and Computing, 2017

A New Collaborative Approach to Particle Swarm Optimization for Global Optimization

Advances in Intelligent Systems and Computing, 2016

Particle swarm optimization (PSO) is population-based metaheuristic algorithm which mimics animal... more Particle swarm optimization (PSO) is population-based metaheuristic algorithm which mimics animal flocking behavior for food searching and widely applied in various fields. In standard PSO, movement behavior of particles is forced by the current bests, global best and personal best. Despite moving toward the current bests enhances convergence, however, there is a high chance for trapping in local optima. To overcome this local trapping, a new updating equation proposed for particles so-called extraordinary particle swarm optimization (EPSO). The particles in EPSO move toward their own targets selected at each iteration. The targets can be the global best, local bests, or even the worst particle. This approach can make particles jump from local optima. The performance of EPSO has been carried out for unconstrained benchmarks and compared to various optimizers in the literature. The optimization results obtained by the EPSO surpass those of standard PSO and its variants for most of benchmark problems.

Impacts of flood on agricultural land use in climate change context

Flooding is one of the main disasters influenced to Vietnam in directly especially the Central Co... more Flooding is one of the main disasters influenced to Vietnam in directly especially the Central Coast. Vu Gia – Thu Bon is one of 9 largest river basins in Vietnam but it also often suffers natural disasters. In the river basin, there is Tieu Man flood in late of May, usually the flood contributes to reduce water stress during dry season. However there are some years which have large Tieu Man flood, and causing serious damages to agricultural production. Under climate change context, impacts of Tieu Man flood on agriculture have been becoming more complex due to combination of flood flow and sea level rise. The thesis is implemented to aim impacts assessment of Tieu Man flood on agriculture under changing of climate and sea level. Since that, the author estimates flood damages on agricultural land use. Thesis uses Mike 11 model package including HD and GIS extension modules to build inundation and duration maps of study area in climate change scenarios and estimates inundation level ...

KU Battle of Metaheuristic Optimization Algorithms 1: Development of Six New/Improved Algorithms

Advances in Intelligent Systems and Computing, 2015

Each of six members of hydrosystem laboratory in Korea University (KU) invented either a new meta... more Each of six members of hydrosystem laboratory in Korea University (KU) invented either a new metaheuristic optimization algorithm or an improved version of some optimization methods as a class project for the fall semester 2014. The objective of the project was to help students understand the characteristics of metaheuristic optimization algorithms and invent an algorithm themselves focusing those regarding convergence, diversification, and intensification. Six newly developed/improved metaheuristic algorithms are Cancer Treatment Algorithm (CTA), Extraordinary Particle Swarm Optimization (EPSO), Improved Cluster HS (ICHS), Multi-Layered HS (MLHS), Sheep Shepherding Algorithm (SSA), and Vision Correction Algorithm (VCA). This paper describes the details of the six developed/improved algorithms. In a follow-up companion paper, the six algorithms are demonstrated and compared through well-known benchmark functions and a real-life engineering problem.

Self-similar characteristics in the organization of natural river networks on the basis of Shreve's ordering scheme

Natural river networks exhibit interesting scaling laws representing their fractal features. One ... more Natural river networks exhibit interesting scaling laws representing their fractal features. One of the most widely-known laws is Horton's law which illustrates log-linear characteristics between the stream order and geomorphological measures (the number of branches, length of branches, and drainage area). Horton's law is based on Horton-Strahler ordering scheme. This ordering scheme apparently creates an omission in accounting of first-order segments which are primary collectors of rainfall within a basin. An alternative ordering scheme is Shreve's ordering scheme. Nevertheless, most studies on river network organization thus far have been implemented on the basis of Horton-Strahler ordering scheme. In this study, we investigate how self-similar characteristics of natural river networks emerge in the Shreve's ordering framework. We investigate whether scaling principles similar with Horton's and Hack's laws appear in the Shreve's framework. Our study on ...

Suggestion of channel component in Tank model

Tank model (Sugawara M. , 1995) has been widely applied for flood simulation in many humid region... more Tank model (Sugawara M. , 1995) has been widely applied for flood simulation in many humid regions. The model is based on a simple concept of treating watershed as a series of tanks (reservoirs). Here, we suggest to add an additional tank to account for channel routing effect. The new model is applied to simulate July flood events at Sanganmi watershed, Korea. By applying optimization algorithm auto-calibration, the appropriate model including a linear channel horizontally vessel and two vertically laid vessels is proposed to simulate flood in the study watershed.

Comparison of parameter-setting-free and self-adaptive harmony search

This study compares the performance of all parameter-setting-free and self-adaptive harmony searc... more This study compares the performance of all parameter-setting-free and self-adaptive harmony search algorithms proposed in the previous studies, which do not ask for the user to set the algorithm parameter values. Those algorithms are parameter-setting-free harmony search, Almost-parameter-free harmony search, novel self-adaptive harmony search, self-adaptive global-based harmony search algorithm, parameter adaptive harmony search, and adaptive harmony search, each of which has a distinctively different mechanism to adaptively control the parameters over iterations. Conventional mathematical benchmark problems of various dimensions and characteristics and water distribution network design problems are used for the comparison. The best, worst, and average values of final solutions are used as performance indices. Computational results show that the performance of each algorithm has a different performance indicator depending on the characteristics of optimization problems such as sear...

Decentralization-based optimization of detention reservoir systems for flood reduction in urban drainage areas

The paper introduces a decentralized approach to optimizing the flood reduction efficiency of mul... more The paper introduces a decentralized approach to optimizing the flood reduction efficiency of multiple detention reservoirs in urban areas. The flood reduction effects of a detention reservoir system were regionally assessed, and a new model was then created using an optimization technique which involved coupling extraordinary particle swarm optimization with a flood simulation engine, Storm Water Management Model, EPA-SWMM, to identify optimal outlet designs for a detention reservoir system. When applied to the To Lich drainage network (Hanoi, Vietnam) the proposed method outperformed the present design, reducing flooding under the design flood event. The performance of the approach was verified by comparing it with the overall objective function of total flooded volume for different design floods. The better performance of the decentralized optimization approach described here, in terms of local and regional flood management, illustrated its effectiveness for urban flooding reduction.

Flood vulnerability assessment at the local scale using remote sensing and GIS techniques: a case study in Da Nang City, Vietnam

Journal of Water and Climate Change

This paper has developed a cost-efficient framework for flood vulnerability assessment at a local... more This paper has developed a cost-efficient framework for flood vulnerability assessment at a local scale using a multi-parametric approach integrated with the Open Source Geographical Information System (GIS) and Open Remote Sensing data. The study focuses on generating a set of criteria considering three dimensions of flood vulnerability: exposure, sensitivity, and adaptive capacity (AC) on an index-based approach. These indicators were decided based on a robust analysis considering the physical and socio-economic conditions of the study area. The flood exposure was generated from the geomorphological and hydrological parameters integrated with the flood water depth, the distance to river channels, and the Modified Normalized Difference Water Index. The flood sensitivity was determined by the aggregation of local income, land use, poverty index, population density, and other parameters reflecting the socio-economic condition. The AC has been evaluated based on the Normalized Differe...

Pre-disaster assessment of flood risk for mid Central Vietnam

International Journal of Disaster Resilience in the Built Environment, 2021

Purpose Nowadays, under climate change contexts, natural disasters are becoming stronger in inten... more Purpose Nowadays, under climate change contexts, natural disasters are becoming stronger in intensity and probability. The impacts of natural disasters on people and the environment are also getting worse. The purpose of this study was conducted to provide a method of assessing disaster risks, in particular, floods for human life in Mid Central Vietnam. Design/methodology/approach The pre-disaster assessment method was used based on the analysis of hazard factors (Hazard-H), exposure to hazards (Exposure-E) and vulnerability (Vulnerability-V). Findings Flood disaster risks in the area are assessed and displayed on spatial maps. The districts in coastal plains of Quang Ngai and Thua Thien Hue provinces have the highest levels of risk. These assessments will play an important role in supporting flood prevention and mitigation in the region. Originality/value According to the authors, this is the first study assessing the flood risk in Vietnam on the pre-disaster perspective. The asses...

Water Scarcity in Vietnam: a Point of View on Virtual Water Perspective

Water Resources Management, 2018

This paper quantifies water consumption of Vietnam in agricultural products on virtual water pers... more This paper quantifies water consumption of Vietnam in agricultural products on virtual water perspective. The calculation of water footprint and virtual water in four major agricultural crops is first implemented for seven regions of the country. The domestic and international trades of virtual water are subsequently investigated to demonstrate the commodity and virtual water flows among regions. The analysis reveals that Mekong River Delta is an important exporter of virtual water in rice product for both domestic and international trades while Central Highland is the main virtual exporter in coffee. The paper also proposes a new water stress index such that it considers both direct and indirect water use given transboundary water resources. The proposed water stress index indicates the actual water scarcity in Vietnam in which the water-rich regions i.e. Red River Delta and Mekong River Delta are in severe water stress.

Decentralization-based optimization of detention reservoir systems for flood reduction in urban drainage areas

Urban Water Journal, 2018

The paper introduces a decentralized approach to optimizing the flood reduction efficiency of mul... more The paper introduces a decentralized approach to optimizing the flood reduction efficiency of multiple detention reservoirs in urban areas. The flood reduction effects of a detention reservoir system were regionally assessed, and a new model was then created using an optimization technique which involved coupling extraordinary particle swarm optimization with a flood simulation engine, Storm Water Management Model, EPA-SWMM, to identify optimal outlet designs for a detention reservoir system. When applied to the To Lich drainage network (Hanoi, Vietnam) the proposed method outperformed the present design, reducing flooding under the design flood event. The performance of the approach was verified by comparing it with the overall objective function of total flooded volume for different design floods. The better performance of the decentralized optimization approach described here, in terms of local and regional flood management, illustrated its effectiveness for urban flooding reduction.

Linear System Theory-Based Optimization of Detention Basin’s Location and Size at Watershed Scale

Journal of Hydrologic Engineering, 2016

AbstractIn the context of urbanization and waterworks construction, detention basins located in u... more AbstractIn the context of urbanization and waterworks construction, detention basins located in upstream tributaries have become one of the most-effective technical solutions for downstream flood reduction. This technical note proposes a new optimal approach for determining the most-effective design combination of detention basins (in terms of their sizes and locations) in a watershed utilizing linear reservoir theory. The optimal detention basin is obtained by minimizing the deviation of downstream peak discharge from river capacity discharge. With the presence of a detention basin in an upstream river, the flood peak downstream decreases by 33%, corresponding to two scenarios of rainfall duration with a return period T=100 years. The storage volume estimation of the optimal detention reservoir proposed in the present paper demonstrates the high applicability of this optimization approach.

A cooperative particle swarm optimizer with stochastic movements for computationally expensive numerical optimization problems

Journal of Computational Science, 2016

Abstract Nature is the rich principal source for developing optimization algorithms. Metaheuristi... more Abstract Nature is the rich principal source for developing optimization algorithms. Metaheuristic algorithms can be classified with the emphasis on the source of inspiration into several categories such as biology, physics, and chemistry. The particle swarm optimization (PSO) is one of the most well-known bio-inspired optimization algorithms which mimics movement behavior of animal flocks especially bird and fish flocking. In standard PSO, velocity of each particle is influenced by the best individual and its best personal experience. This approach could make particles trap into the local optimums and miss opportunities of jumping to far better optimums than the currents and sometimes causes fast premature convergence. To overcome this issue, a new movement concept, so called extraordinariness particle swarm optimizer (EPSO) is proposed in this paper. The main contribution of this study is proposing extraordinary motion for particles in the PSO. Indeed, unlike predefined movement used in the PSO, particles in the EPSO can move toward a target which can be global best, local bests, or even the worst individual. The proposed improved PSO outperforms than the standard PSO and its variants for benchmarks such as CEC 2015 benchmarks. In addition, several constrained and engineering design problems have been tackled using the improved PSO and the optimization results have been compared with the standard PSO, variants of PSO, and other optimizers.

Robust Urban Drainage System: Development of a Novel Multiscenario-Based Design Approach

Journal of Water Resources Planning and Management, 2019

A traditional single-scenario design approach considers the most probable future scenario, which ... more A traditional single-scenario design approach considers the most probable future scenario, which is very risky and may result in high supplementary cost or overpayment (i.e., regret cost). An alternative involves simultaneously considering multiple scenarios. The present study proposes a novel two-phase multiscenario-based design approach to optimize the layout and hydraulic design (determining pipe sizes and manhole depths) of an urban sewer system. In the first phase, multiple individual scenarios are adopted to independently identify the optimal layout for each scenario and the requisite hydraulic design. The aim of the second phase involves determining robust solutions for the sewer layout and hydraulic design to minimize construction cost with a constraint on acceptable regret costs over multiple scenarios. The proposed two-phase optimization method is demonstrated with a hypothetical example of an urban drainage system. The results indicate that the proposed multiscenario optimization approach produces a robust sewer network solution that performs well and is cost-effective for different scenarios.

Optimization of Upstream Detention Reservoir Facilities for Downstream Flood Mitigation in Urban Areas

Water, 2016

A detention reservoir is one of the most effective engineered solutions for flood damage mitigati... more A detention reservoir is one of the most effective engineered solutions for flood damage mitigation in urban areas. Detention facilities are constructed to temporarily store storm water and then slowly drain when the peak period has passed. This delayed drainage may coincide with upstream floods and aggravate the flood risk downstream. Optimal operation and design are needed to improve the performance of detention reservoirs for flood reduction. This study couples hydrologic simulation software (EPA-SWMM) with an evolutional optimizer (extraordinary particle swarm optimization, EPSO) to minimize flood damage downstream while considering the inundation risk at the detention reservoir. The optimum design and operation are applied to an urban case study in Seoul, Korea, for historical severe flooding events and designed rainfall scenarios. The optimal facilities outperform the present facilities in terms of flood damage reduction both downstream and in the detention reservoir area. Specifically, the peak water level at the detention pond under optimal conditions is significantly smaller than that of the current conditions. The comparison of the total flooded volume in the whole watershed shows a dramatic reduction of 79% in a severe flooding event in 2010 and around 20% in 2011 and in 180 min designed rainfall scenarios.

The Extraordinary Particle Swarm Optimization and Its Application in Constrained Engineering Problems

Advances in Intelligent Systems and Computing

The particle swarm optimization (PSO) is a natural-inspire optimization algorithm mimicking the m... more The particle swarm optimization (PSO) is a natural-inspire optimization algorithm mimicking the movement behavior of animal flocks for food searching. Although the algorithm presents some advantages and widely application, however, there are several drawbacks such as trapping in local optima and immature convergence rate. To overcome these disadvantages, many improved versions of PSO have been proposed. One of the latest variants is the extraordinary particle swarm optimization (EPSO). The particles in the EPSO are assigned to move toward their own determined target through the search space. The applicability of EPSO is verified by several experiments in engineering optimization problems. The application results show the outperformance of the EPSO than the other PSO variants in terms of solution searching and as well as convergence rate.

Self-similarity characteristics in the organization of natural river networks on the basis of Shreve ’ s ordering scheme

Natural river networks exhibit interesting scaling laws representing their fractal features. One ... more Natural river networks exhibit interesting scaling laws representing their fractal features. One of the most widely-known laws is Horton’s law which illustrates log-linear characteristics between the stream order and geomorphological measures (the number of branches, length of branches, and drainage area). Horton’s law is based on Horton-Strahler ordering scheme. This ordering scheme apparently creates an omission in accounting of first-order segments which are primary collectors of rainfall within a basin. An alternative ordering scheme is Shreve’s ordering scheme. Nevertheless, most studies on river network organization thus far have been implemented on the basis of Horton-Strahler ordering scheme. In this study, we investigate how self-similarity characteristics of natural river networks emerge in the Shreve’s ordering framework. We investigate whether scaling principles similar with Horton’s and Hack’s laws appear in the Shreve’s framework. Our study on a Vietnamese river basin ...

Estimation of Pump Capacity in Detention Reservoir for Reducing Urban Inundation

An Efficient Algorithm Based on Neu ral Networks for Solving Differential Equations Arising in Engineering Applications

Numerical Solution of Boundary Value Problems Using Artificial Neural Networks and Harmony Search

Advances in Intelligent Systems and Computing, 2017

A New Collaborative Approach to Particle Swarm Optimization for Global Optimization

Advances in Intelligent Systems and Computing, 2016

Particle swarm optimization (PSO) is population-based metaheuristic algorithm which mimics animal... more Particle swarm optimization (PSO) is population-based metaheuristic algorithm which mimics animal flocking behavior for food searching and widely applied in various fields. In standard PSO, movement behavior of particles is forced by the current bests, global best and personal best. Despite moving toward the current bests enhances convergence, however, there is a high chance for trapping in local optima. To overcome this local trapping, a new updating equation proposed for particles so-called extraordinary particle swarm optimization (EPSO). The particles in EPSO move toward their own targets selected at each iteration. The targets can be the global best, local bests, or even the worst particle. This approach can make particles jump from local optima. The performance of EPSO has been carried out for unconstrained benchmarks and compared to various optimizers in the literature. The optimization results obtained by the EPSO surpass those of standard PSO and its variants for most of benchmark problems.

Impacts of flood on agricultural land use in climate change context

Flooding is one of the main disasters influenced to Vietnam in directly especially the Central Co... more Flooding is one of the main disasters influenced to Vietnam in directly especially the Central Coast. Vu Gia – Thu Bon is one of 9 largest river basins in Vietnam but it also often suffers natural disasters. In the river basin, there is Tieu Man flood in late of May, usually the flood contributes to reduce water stress during dry season. However there are some years which have large Tieu Man flood, and causing serious damages to agricultural production. Under climate change context, impacts of Tieu Man flood on agriculture have been becoming more complex due to combination of flood flow and sea level rise. The thesis is implemented to aim impacts assessment of Tieu Man flood on agriculture under changing of climate and sea level. Since that, the author estimates flood damages on agricultural land use. Thesis uses Mike 11 model package including HD and GIS extension modules to build inundation and duration maps of study area in climate change scenarios and estimates inundation level ...

KU Battle of Metaheuristic Optimization Algorithms 1: Development of Six New/Improved Algorithms

Advances in Intelligent Systems and Computing, 2015

Each of six members of hydrosystem laboratory in Korea University (KU) invented either a new meta... more Each of six members of hydrosystem laboratory in Korea University (KU) invented either a new metaheuristic optimization algorithm or an improved version of some optimization methods as a class project for the fall semester 2014. The objective of the project was to help students understand the characteristics of metaheuristic optimization algorithms and invent an algorithm themselves focusing those regarding convergence, diversification, and intensification. Six newly developed/improved metaheuristic algorithms are Cancer Treatment Algorithm (CTA), Extraordinary Particle Swarm Optimization (EPSO), Improved Cluster HS (ICHS), Multi-Layered HS (MLHS), Sheep Shepherding Algorithm (SSA), and Vision Correction Algorithm (VCA). This paper describes the details of the six developed/improved algorithms. In a follow-up companion paper, the six algorithms are demonstrated and compared through well-known benchmark functions and a real-life engineering problem.

Self-similar characteristics in the organization of natural river networks on the basis of Shreve's ordering scheme

Natural river networks exhibit interesting scaling laws representing their fractal features. One ... more Natural river networks exhibit interesting scaling laws representing their fractal features. One of the most widely-known laws is Horton's law which illustrates log-linear characteristics between the stream order and geomorphological measures (the number of branches, length of branches, and drainage area). Horton's law is based on Horton-Strahler ordering scheme. This ordering scheme apparently creates an omission in accounting of first-order segments which are primary collectors of rainfall within a basin. An alternative ordering scheme is Shreve's ordering scheme. Nevertheless, most studies on river network organization thus far have been implemented on the basis of Horton-Strahler ordering scheme. In this study, we investigate how self-similar characteristics of natural river networks emerge in the Shreve's ordering framework. We investigate whether scaling principles similar with Horton's and Hack's laws appear in the Shreve's framework. Our study on ...

Suggestion of channel component in Tank model

Tank model (Sugawara M. , 1995) has been widely applied for flood simulation in many humid region... more Tank model (Sugawara M. , 1995) has been widely applied for flood simulation in many humid regions. The model is based on a simple concept of treating watershed as a series of tanks (reservoirs). Here, we suggest to add an additional tank to account for channel routing effect. The new model is applied to simulate July flood events at Sanganmi watershed, Korea. By applying optimization algorithm auto-calibration, the appropriate model including a linear channel horizontally vessel and two vertically laid vessels is proposed to simulate flood in the study watershed.

Comparison of parameter-setting-free and self-adaptive harmony search

This study compares the performance of all parameter-setting-free and self-adaptive harmony searc... more This study compares the performance of all parameter-setting-free and self-adaptive harmony search algorithms proposed in the previous studies, which do not ask for the user to set the algorithm parameter values. Those algorithms are parameter-setting-free harmony search, Almost-parameter-free harmony search, novel self-adaptive harmony search, self-adaptive global-based harmony search algorithm, parameter adaptive harmony search, and adaptive harmony search, each of which has a distinctively different mechanism to adaptively control the parameters over iterations. Conventional mathematical benchmark problems of various dimensions and characteristics and water distribution network design problems are used for the comparison. The best, worst, and average values of final solutions are used as performance indices. Computational results show that the performance of each algorithm has a different performance indicator depending on the characteristics of optimization problems such as sear...

Decentralization-based optimization of detention reservoir systems for flood reduction in urban drainage areas

The paper introduces a decentralized approach to optimizing the flood reduction efficiency of mul... more The paper introduces a decentralized approach to optimizing the flood reduction efficiency of multiple detention reservoirs in urban areas. The flood reduction effects of a detention reservoir system were regionally assessed, and a new model was then created using an optimization technique which involved coupling extraordinary particle swarm optimization with a flood simulation engine, Storm Water Management Model, EPA-SWMM, to identify optimal outlet designs for a detention reservoir system. When applied to the To Lich drainage network (Hanoi, Vietnam) the proposed method outperformed the present design, reducing flooding under the design flood event. The performance of the approach was verified by comparing it with the overall objective function of total flooded volume for different design floods. The better performance of the decentralized optimization approach described here, in terms of local and regional flood management, illustrated its effectiveness for urban flooding reduction.