Hydrosystems Laboratory

Water Supply System Management
Water supply system is an essential infrastructures for human life. The main purpose of water supply system is to supply adequate quantity of fresh water with sufficient pressure. Therefore the design and analysis of water supply systems are very important. Water supply system generally includes drainage basins, raw water collection points, water purification facilities, water storage facilities, water pressurizing components and distribution pipes. Hydrosystems laboratory has been studying on the Design and Analysis of water distribution networks (WDNs) in ‘Design and Construction of Smart DMA in Water Distribution Networks’ project supported by the Ministry of Environment, Korea. WDN, one of the parts in the water supply system, consists of reservoirs, tanks, pipes, pumps, valves and demand areas.
Urban Drainage System Management
Recent climate changes increased the likelihood of heavy rainfall in urban area in Korea, which can cause devastating property damage and loss of life. The importance of urban inundation prevention will also increase. In order to mitigate the impact of urban inundation on the system, structural solutions such as improvement of efficiency in hydraulic structure, making urban drainage plan and increasing the size of sewer conduits has been adopted in the urban drainage system. However, structural solutions are not a cost-effective alternative. Furthermore, most urban cities are lack of space for new hydraulic structure to capture the run-off in a developed area (e.g., constructing a detention basin). High-level technology such as optimal operation of combined drainage systems among non-structural solutions in urban area is not sufficient for overcoming these drawbacks.
Hydro systems laboratory has researched about urban drainage system management in two projects: ‘Development of Advanced Techniques in Combined Inland-River Systems for Reducing Urban Inundation’ supported by the Ministry of Public Safety and Security and ‘Development of GIS based Pump Station Operation with Decision Support System’ supported by Small and Medium Business Administration.
Optimization Algorithms (Meta-heuristics)
Optimization is the process of selecting a bestelement from some sets of available alternatives according to some criteria. Ineach iteration of the optimization process, choosing the values from within anallowed set is done systematically until the minimum or maximum result isreached or when the stopping criterion is met. Meta-heuristic algorithms arewell-known optimization algorithms which can solve optimization problems withsatisfying a set of constraints.
Harmony Search Algorithm
TheHarmony Search (HS) algorithm was developed by Prof. Kim and Dr. Geem (a formermember of Hydrosystems lab) is one of the most recently developed optimizationalgorithm and at the same time, it is one the most efficient algorithm in thefield of combinatorial optimization.
The HS algorithm was inspired by musical performanceprocess involving searching for a best harmony. When the orchestra membersfirst practice, there can be the good and bad harmonies. While practicing, badharmonies are removed, and finally it creates the fantastic harmony (optimal solution).Since the HS algorithm was first developed in 2001, the HS was initiallyapplied in well-known benchmark problem (e.g., De Jong functions), parameterestimation, travelling salesman problem, and optimal design of water distributionnetworks (WDNs).
In the HS’s applications of practical problems,however, studies about water resources and structural engineering hold largemajority in the early stage because the major field of the developer is a civilengineering (CE). Since 2001, it has been applied to various engineeringproblems, and the international attention on it has rapidly increased.
In each iteration of the HS algorithm, a new solutionis generated either by random search (RS) or by harmony memory consideration(HMC) followed by pitch adjusting (PA). HMC is performed with a probability ofharmony memory considering rate (HMCR) while PA is processed with a probabilityof a pitch adjustment rate (PAR). In addition, harmony memory size (HMS) indicatingthe size of memory space (harmony memory, HM) and band width (BW) defining theallowable range of PA are used as the parameters.
In the early stage, some studies attempted to modifythe parameters called the modified HS, revised HS, and improved HS. Recently,self-adaptive or parameter setting free versions of HS have been developed inan effort to avoid providing initial values of decision variables as well aschanging the parameter values manually in the course of the search. Recently,hybrid HSs and multi-objective HSs has been developing.
In applications aspects, the HS was initially appliedin benchmark and simple engineering problems to verify the applicability of thealgorithm itself. Recently, however, it has been used and utilized in thereal-world problems. The application results show that HS can be effectivelyused as tool for optimization problems. Therefore, it can be recommended as theworld-wide optimization techniques, and it also can be used in wide range ofengineering field.
Water Cycle Algorithm
Water Cycle Algorithm (WCA) as a recently developedoptimizer is introduced by Eskandar et al. (2012). The fundamental concepts andideas which underlie the WCA is inspired by nature and based on the observationof water cycle process and how rivers and streams flow to the sea in the realworld. A comparative study has been carried out to show the effectiveness ofthe WCA over other well-known optimizers in terms of computational effort(measures as number of function evaluations) and function value (accuracy) fortruss structures, unconstrained, constrained engineering design problems, and multi-objectiveoptimization problems. Below is the schematic view of the processes for theWCA, where circles, stars, and the diamond correspond to streams, rivers, andsea, respectively.
Mine Blast Algorithm
Mine Blast Algorithm (MBA) is a recently developedoptimization method used for handling complex optimization problems introducedby Sadollah et al. (2012). The fundamental concepts and ideas of the MBA arederived by the explosion of mines in real world. The efficiency of the proposedoptimizer is tested via the optimization of several truss structures havingdiscrete variables, unconstrained and constrained engineering design problems,and multi-objective optimization problems.
The performance of the MBA is compared with several well-knownmetaheuristic algorithms given in the literature. The obtained optimizationresults show that the MBA is able to provide faster convergence rate and alsomanages to achieve better optimal solutions compared to the other efficientoptimizers. Below is the schematic view of the processes (concentric lines for explorationphase and solid lines for exploitation phase) for the MBA.