Papers by Nicos Theodossiou
After its first presentation in 2000, Harmony Search Algorithm, a new optimization technique has ... more After its first presentation in 2000, Harmony Search Algorithm, a new optimization technique has gained the scientific interest of those involved in optimization simulation. This technique is based on an analogy between music creation and optimization. In the same way musicians seek for the perfect state of Harmony, HSA seeks for the best solution of a specific problem. This optimization algorithm involves the use of 3 mechanisms: Harmony Memory Consideration, Pitch Adjustment and Randomization. Tuning the parameters of these mechanisms and defining the size of the initial “music material” is a common problem in HSA’s applications. In the present paper a calibration of these parameters is presented in detail, along with their influence in the total performance of the Algorithm. In order to achieve that, 2 benchmark test functions have been used. These functions, named Rosenbrock and Griewangk respectively, are regarded as very accurate and demanding trials and have been already used...
The determination of wellhead protection areas is a matter of major importance especially for wel... more The determination of wellhead protection areas is a matter of major importance especially for wells supplying water for domestic use, since it allows water resources managers and local authorities to impose measures over the development of agricultural or industrial activities that could somehow affect the quality of groundwater. In this paper an investigation, using computer-based mathematical models, of the implications of uncertainty on the estimation of the hydrogeological parameters that affect the delineation of wellhead protection areas is performed. This investigation is based on a stochastic simulation of the soil material structure of the aquifer. The economic aspects of the measures imposed over the protected areas according to their resulting delineation are then analysed in order to establish a measure of the costs of information and of the degree of uncertainty of the hydrogeological parameters.
The need to develop and apply new optimization techniques in order to achieve more efficient and ... more The need to develop and apply new optimization techniques in order to achieve more efficient and effective solutions in complex management problems, has led to the introduction of a series of interesting new methods. The meta-heuristic method of music-based Harmony Search Algorithm (HSA) is one of the leading optimization techniques nowadays with applications covering a wide range of scientific fields, including of course, water resources management. In this paper, a classical water allocation problem, the one introduced by Louks et al in 1981, is being solved with HSA. For this application a specially designed computer software programmed in MATLAB environment is used. The created software includes a friendly GUI (Graphical User Interface) that allows the user to easily interact with the optimization tool.
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... 1. DESCRIPTION OF THE STUDY AREA The municipality of Moudania is located in the western part ... more ... 1. DESCRIPTION OF THE STUDY AREA The municipality of Moudania is located in the western part of the prefecture of Chalkidiki, a peninsula with a distinct shape in northern Greece. ... 10. Meladiotis J. (2003) "Engineering Geology II", Notes, Thessaloniki. 11. ...
The present study aims to develop a problem-independent, generic optimization toolkit applicable ... more The present study aims to develop a problem-independent, generic optimization toolkit applicable to engineering optimization problems. The authors designed a program in MATLAB environment, using a Harmony Search Algorithm (HSA) in its core. A Java-based Optimization Toolkit has also been developed, taking advantage of the inherent features of object-oriented Java. Both programs allow for optimization using the HSA, which is a recent development among metaheuristics, inspired from the music creation process. Since its presentation in 2001, HSA has attracted the interest of those involved in the opti-mization field and thus has been successfully applied in different implementations. HSA was initially designed to optimize urban water distribution networks. Since then its application has has expanded to a remarkably wide range of scientific disciplines. Although the authors' in-tention is to address water engineering, hydroelectric energy production and renewable energy related prob...
Issue 3, 2013
The importance of the development and application of groundwater simulation mathematical models i... more The importance of the development and application of groundwater simulation mathematical models in the protection of aquifer systems is nowadays recognised as an undisputable fact. In this paper a mathematical model that was developed in order to simulate the operation of the Upper Anthemountas aquifer in Chalkidiki, Greece, is presented. The case study application investigated concerned the possible malfunction of the Waste Water Treatment Plant located within the study area. According to this scenario a possible malfunction of the treatment plant could pollute the underlying aquifer. A network of observation wells located downstream of the plant could detect the pollution and predict the time needed to reach the productive wells surrounding the area. This allows the local water resources managers to formulate a priori action-plans including, the alteration of the pumping schedule in order to prevent polluted water to be abstracted from the nearby wells and at the same time protect...
Desalination and Water Treatment, 2015
AbstractTwenty-seven (27) tap water samples were collected during October 2012 from the supply ne... more AbstractTwenty-seven (27) tap water samples were collected during October 2012 from the supply network of Thermi Municipality (central Macedonia, northern Greece) in order to assess their hydrogeochemical signatures and the overall quality status according to the European legislation and international standards. Samples were analysed for a total of 25 environmentally significant parameters including physicochemical properties (pH, EC, colour, turbidity and hardness), major and minor ions (Ca2+, Mg2+, , , , Cl−, , F−, and CN−) and trace elements (B, Sb, As, Cd, Cr, Cu, Pb, Hg, Ni, Se, and Mn). The vast majority of the parameters appeared in values below the maximum admissible concentration for potable waters. Individual elevated concentrations of B and may be attributed to natural (geogenic) factors related with local lithology and anthropogenic influences possibly deriving from agricultural practices (excessive use of N-fertilizers). The assessments of the analytical results were validated with the use of...
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Papers by Nicos Theodossiou