Research Publications Authored by SLIIT Staff

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This collection includes all SLIIT staff publications presented at external conferences and published in external journals. The materials are organized by faculty to facilitate easy retrieval.

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Author: search.filters.author.Rathnayake, U. SSubject: search.filters.subject.genetic algorithms

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Now showing 1 - 4 of 4
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    PublicationOpen Access
    OPTIMAL CONTROL OF URBAN SEWER SYSTEMS–WHERE DO WE STAND TODAY?
    (SAITM, 2014-04-26) Rathnayake, U. S
    Combined sewer overflows (CSOs) are identified as one of the major environmental concerns at most of the cities to date. These untreated combined sewer overflows are directly discharged to the nearby natural water bodies and cause many environmental problems because of the increased pollution levels at natural water bodies. Constructing additional storage facilities, increasing conduit capacity, expanding pumping capacity and application of controlling strategies to utilize the existing storage in sewer network are the common mitigation solutions of CSOs. This research paper targets to present the state of art of control of combined sewer systems, including the author’s current research work in developing a holistic optimal control model for combined sewer systems.
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    PublicationEmbargo
    Static optimal control of combined sewer networks under enhanced cost functions to minimize the adverse environmental effects
    (Taylor & Francis, 2018-11-08) Rathnayake, U. S
    Capacity limitations of combined sewer systems lead overflows (CSOs) especially under intensified rain events. The socio-economic damage due to these CSOs on receiving water is immeasurable. Structural measures include enhancing the existing pipe network and introducing new sewer systems lead extra burden on the inhabitants due to new constructions. In addition, the taxpayers have to bear the construction cost. Optimal control of existing combined sewer systems is one of the non-structural solutions in minimizing the adverse impacts of CSOs; however, a holistic control algorithm based on water quality of the receiving water is yet to be developed. This paper develops an enhanced control algorithm based on the pollution load to the receiving water from CSOs. Unlike the previous studies, this paper looks at an enhanced cost function for one of the objective functions, which includes the pumping cost of combined sewer network. The control algorithm is generic; however, it is tested against a real world combined sewer network in Liverpool, United Kingdom. Optimal control settings of the combined sewer systems are found and further analysis shows that algorithm gives feasible solutions. Therefore, the results have proved the applicability of the newly developed optimization algorithm in control of combined sewer systems.
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    PublicationOpen Access
    Optimal control of combined sewer overflows
    (DAVID PUBLISHING, 2021) Rathnayake, U. S
    : Combined sewer networks carry wastewater and stormwater together. Capacity limitation of these sewer networks results in combined sewer overflows (CSOs) during high-intensity storms. Untreated CSOs when directly discharged to the nearby natural water bodies cause many environmental problems. Controlling existing urban sewer networks is one possible way of addressing the issues in urban wastewater systems. However, it is still a challenge, when considering the receiving water quality effects. This paper presents an evolutionary constrained multi-objective optimization approach to control the existing combined sewer networks. The control of online storage tanks was taken into account when controlling the combined sewer network. The developed multi-objective approach considers two important objectives, i.e. the pollution load to the receiving water from CSOs and the cost of the wastewater treatment. The proposed optimization algorithm is applied here to a realistic interceptor sewer system to demonstrate its effectiveness.
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    PublicationOpen Access
    Multi-objective optimization of combined sewer systems using SWMM 5.0
    (2015-10-25) Rathnayake, U. S
    Combined sewer overflows (CSOs) are frequent in many cities during stormy weather. CSOs are not only an environmental issue but also induce an adverse aesthetic view for major cities, worldwide. Many engineering solutions have been proposed by researchers to reduce, if possible to avoid CSOs; however, most of these solutions require sewer network capacity enhancement. Therefore, most of the proposed engineering solutions are based on structural measures. However, they are not the best solutions since most of these measures require new structural components and thus capital requirement. Therefore, if possible, control of existing combined sewer networks to minimize the CSOs and their adverse environmental effects would be an ideal solution. However, a holistic control algorithm based on environmental concerns is yet to be tabled. Therefore, this paper presents an improved approach in control of existing combined sewer systems to minimize the adverse environmental effects due to the combined sewer overflows. A multi-objective optimization approach was developed, considering flows and water quality in combined sewer flows and the wastewater treatment costs. The presented multi-objective optimization approach shows a considerable improvement in controlling urban wastewater systems compared to the previous work by the same author. The improved algorithm has advantages in solution space of multi-objective optimization approach. Furthermore, it eliminates achievement of infeasible solutions unlike the other constrained multi-objective optimization approaches