Imperial College London

DrIvanStoianov

Faculty of EngineeringDepartment of Civil and Environmental Engineering

Senior Lecturer
 
 
 
//

Contact

 

+44 (0)20 7594 6035ivan.stoianov Website

 
 
//

Assistant

 

Miss Judith Barritt +44 (0)20 7594 5967

 
//

Location

 

408Skempton BuildingSouth Kensington Campus

//

Summary

 

Publications

Publication Type
Year
to

59 results found

Ulusoy A, Stoianov I, Chazerain A, 2018, Hydraulically informed graph theoretic measure of link criticality for the resilience analysis of water supply networks, Applied Network Science, Vol: 3, ISSN: 2364-8228

Water Distribution Networks (WDN) are complex and highly interconnected systems. To maintain operation under failure conditions, WDNs should have built-in resilience based on topological and energy redundancy. There are various methods for analysing the resilience of WDNs based on either hydraulic models or surrogate network measures; however, not a single universally accepted method exists. Hydraulic modeling of disruptive operational scenarios suffer from combinatorial restrictions and uncertainties. Methods that rely on surrogate network measures do not take into account the complex interactions between topological and energy redundancy. To bridge this gap, the presented work introduces a hydraulically informed surrogate measure of pipe criticality for the resilience analysis of WDNs, called Water Flow Edge Betweenness Centrality (WFEBC). The WFEBC combines the random walk betweenness centrality with hydraulic (energy) loss principles in pipes. The proposed network resilience estimation method is applied to a case study network and an operational network. Furthermore, a network decomposition approach is proposed to complement the network estimation method and facilitate its scalability to large operational networks. The described resilience analysis method is benchmarked against a hydraulic model-based analysis of WDN reserve capacity. WFEBC is also applied to assess the improvement in resilience allowed by the implementation of a dynamically adaptive topology in an operational network. The benefits and limitations of the proposed method are discussed.

JOURNAL ARTICLE

Pecci F, Abraham E, Stoianov I, Model reduction and outer approximation for optimising the placement of control valves in complex water networks, Journal of Water Resources Planning and Management, ISSN: 0733-9496

The optimal placement and operation of pressure control valves in water distribution networks is a challenging engineering problem. When formulated in a mathematical optimisation frame work, this problem results in a nonconvex mixed integer nonlinear program (MINLP), which has combinatorial computational complexity. As a result, the considered MINLP becomes particularly difficult to solve for large-scale looped operational networks. We extend and combine network model reduction techniques with the proposed optimisation framework in order to lower the computational burden and enable the optimal placement and operation of control valves in these complex water distribution networks. An outer approximation algorithm is used to solve the considered MINLPs on reduced hydraulic models. We demonstrate that the restriction of the considered optimisation problem on a reduced hydraulic model is not equivalent to solving the original larger MINLP, and its solution is therefore sub-optimal. Consequently, we investigate the trade-off between reducing computational complexity and the potential sub-optimality of the solutions that can be controlled with a parameter of the model reduction routine. The efficacy of the proposed method is evaluated using two large scale water distribution network models.

JOURNAL ARTICLE

Armand H, Stoianov I, Graham N, 2018, Impact of network sectorisation on water quality management, Journal of Hydroinformatics, Vol: 20, Pages: 424-439, ISSN: 1464-7141

JOURNAL ARTICLE

Pecci F, Abraham E, Stoianov I, 2018, Global optimality bounds for the placement of control valves in water supply networks, Optimization and Engineering, ISSN: 1389-4420

© 2018, The Author(s). This manuscript investigates the problem of optimal placement of control valves in water supply networks, where the objective is to minimize average zone pressure. The problem formulation results in a nonconvex mixed integer nonlinear program (MINLP). Due to its complex mathematical structure, previous literature has solved this nonconvex MINLP using heuristics or local optimization methods, which do not provide guarantees on the global optimality of the computed valve configurations. In our approach, we implement a branch and bound method to obtain certified bounds on the optimality gap of the solutions. The algorithm relies on the solution of mixed integer linear programs, whose formulations include linear relaxations of the nonconvex hydraulic constraints. We investigate the implementation and performance of different linear relaxation schemes. In addition, a tailored domain reduction procedure is implemented to tighten the relaxations. The developed methods are evaluated using two benchmark water supply networks and an operational water supply network from the UK. The proposed approaches are shown to outperform state-of-the-art global optimization solvers for the considered benchmark water supply networks. The branch and bound algorithm converges to good quality feasible solutions in most instances, with bounds on the optimality gap that are comparable to the level of parameter uncertainty usually experienced in water supply network models.

JOURNAL ARTICLE

Abraham E, Stoianov I, 2017, Constraint-Preconditioned Inexact Newton Method for Hydraulic Simulation of Large-Scale Water Distribution Networks, IEEE Transactions on Control of Network Systems, Vol: 4, Pages: 610-619

JOURNAL ARTICLE

Pecci F, Abraham E, Stoianov I, 2017, Quadratic head loss approximations for optimisation problems in water supply networks, JOURNAL OF HYDROINFORMATICS, Vol: 19, Pages: 493-506, ISSN: 1464-7141

JOURNAL ARTICLE

Pecci F, Abraham E, Stoianov I, 2017, Penalty and relaxation methods for the optimal placement and operation of control valves in water supply networks, COMPUTATIONAL OPTIMIZATION AND APPLICATIONS, Vol: 67, Pages: 201-223, ISSN: 0926-6003

JOURNAL ARTICLE

Menke R, Kadehjian K, Abraham E, Stoianov IIet al., Investigating trade-offs between the operating cost and green house gas emissions from water distribution systems, Sustainable Energy Technologies and Assessments, ISSN: 2213-1388

JOURNAL ARTICLE

Pecci F, Abraham E, Stoianov I, 2017, Scalable Pareto set generation for multiobjective co-design problems in water distribution networks: a continuous relaxation approach, STRUCTURAL AND MULTIDISCIPLINARY OPTIMIZATION, Vol: 55, Pages: 857-869, ISSN: 1615-147X

JOURNAL ARTICLE

Menke R, Abraham E, Parpas P, Stoianov Iet al., 2017, Extending the envelope of demand response provision though variable speed pumps, 18th International Conference on Water Distribution System Analysis (WDSA), Publisher: ELSEVIER SCIENCE BV, Pages: 584-591, ISSN: 1877-7058

CONFERENCE PAPER

Armand H, Stoianov II, Graham NJD, 2017, A holistic assessment of discolouration processes in water distribution networks, URBAN WATER JOURNAL, Vol: 14, Pages: 263-277, ISSN: 1573-062X

JOURNAL ARTICLE

Pecci F, Abraham E, Stoianov I, 2017, Outer approximation methods for the solution of co-design optimisation problems in water distribution networks, 20th World Congress of the International-Federation-of-Automatic-Control (IFAC), Publisher: ELSEVIER SCIENCE BV, Pages: 5373-5379, ISSN: 2405-8963

CONFERENCE PAPER

Menke R, Abraham E, Parpas P, Stoianov Iet al., 2016, Exploring Optimal Pump Scheduling in Water Distribution Networks with Branch and Bound Methods, WATER RESOURCES MANAGEMENT, Vol: 30, Pages: 5333-5349, ISSN: 0920-4741

JOURNAL ARTICLE

Menke R, Abraham E, Parpas P, Stoianov Iet al., 2016, Demonstrating demand response from water distribution system through pump scheduling, APPLIED ENERGY, Vol: 170, Pages: 377-387, ISSN: 0306-2619

JOURNAL ARTICLE

Abraham E, Stoianov I, 2016, Sparse Null Space Algorithms for Hydraulic Analysis of Large-Scale Water Supply Networks, Journal of Hydraulic Engineering, Vol: 142, Pages: 04015058-04015058, ISSN: 0733-9429

JOURNAL ARTICLE

Herrera M, Abraham E, Stoianov I, 2016, A Graph-Theoretic Framework for Assessing the Resilience of Sectorised Water Distribution Networks, Water Resources Management, Vol: 30, Pages: 1685-1699, ISSN: 0920-4741

JOURNAL ARTICLE

Abraham E, Stoianov I, An efficient null space inexact Newton method for hydraulic simulation of water distribution networks, ArXiv e-prints

JOURNAL ARTICLE

Menke RMM, Abraham EA, Stoianov IS, Modeling variable speed pumps for optimal pumpscheduling, World Environment and Water resource congress

Increasingly more variable speed drive pumps are installed in water distributionsystems worldwide. However, the modeling of variable speed drives in such networksremains difficult, especially in the context of mathematical optimization for pumpscheduling. For the problem of energy usage minimization, formulated as a mixedinteger program, we propose a new simplified convex relaxation of the hydrauliccharacteristics of a variable speed pump. By using different model approximations forthe power curve, as a function of pump speed and volumetric flow rate, we study thetrade-off in the computational complexity and quality of solutions obtained. We usetwo small benchmark networks and real pump data from three different pumps tocalculate operating schedules. We show that these schedules, are computed in a timesuitable for operational usage, enable operation with lower operating cost compared tofixed speed pumps, and their sub-optimality can be computed.

CONFERENCE PAPER

Wright R, Abraham E, Parpas P, Stoianov Iet al., 2015, Control of water distribution networks with dynamic DMA topology using strictly feasible sequential convex programming, WATER RESOURCES RESEARCH, Vol: 51, Pages: 9925-9941, ISSN: 0043-1397

JOURNAL ARTICLE

Wright R, Parpas P, Stoianov I, 2015, Experimental investigation of resilience and pressure management in water distribution networks, Computing and Control for the Water Industry (CCWI2015)- Sharing the Best Practice in Water Management, Publisher: ELSEVIER SCIENCE BV, Pages: 643-652, ISSN: 1877-7058

CONFERENCE PAPER

Pecci F, Abraham E, Stoianov I, 2015, Mathematical programming methods for pressure management in water distribution systems, Computing and Control for the Water Industry (CCWI2015)- Sharing the Best Practice in Water Management, Publisher: ELSEVIER SCIENCE BV, Pages: 937-946, ISSN: 1877-7058

CONFERENCE PAPER

Menke R, Abraham E, Parpas P, Stoianov Iet al., 2015, Approximation of system components for pump scheduling optimisation, Computing and Control for the Water Industry (CCWI2015)- Sharing the Best Practice in Water Management, Publisher: ELSEVIER SCIENCE BV, Pages: 1059-1068, ISSN: 1877-7058

CONFERENCE PAPER

Wright R, Abraham E, Parpas P, Stoianov Iet al., 2015, Optimized control of pressure reducing valves in water distribution networks with dynamic topology, Computing and Control for the Water Industry (CCWI2015)- Sharing the Best Practice in Water Management, Publisher: ELSEVIER SCIENCE BV, Pages: 1003-1011, ISSN: 1877-7058

CONFERENCE PAPER

Armand H, Stoianov I, Graham N, 2015, Investigating the impact of sectorized networks on discoloration, Computing and Control for the Water Industry (CCWI2015)- Sharing the Best Practice in Water Management, Publisher: ELSEVIER SCIENCE BV, Pages: 407-415, ISSN: 1877-7058

CONFERENCE PAPER

Wright R, Herrera M, Parpas P, Stoianov Iet al., 2015, Hydraulic resilience index for the critical link analysis of multi-feed water distribution networks, Computing and Control for the Water Industry (CCWI2015)- Sharing the Best Practice in Water Management, Publisher: ELSEVIER SCIENCE BV, Pages: 1249-1258, ISSN: 1877-7058

CONFERENCE PAPER

Herrera M, Abraham E, Stoianov I, 2015, Graph-theoretic Surrogate Measures for Analysing the Resilience of Water Distribution Networks, Pages: 1241-1248, ISSN: 1877-7058

CONFERENCE PAPER

Abraham E, Stoianov I, 2015, Efficient Preconditioned Iterative Methods for Hydraulic Simulation of Large Scale Water Distribution Networks, Pages: 623-632, ISSN: 1877-7058

CONFERENCE PAPER

Wright R, Stoianov I, Parpas P, Henderson K, King Jet al., 2014, Adaptive water distribution networks with dynamically reconfigurable topology, JOURNAL OF HYDROINFORMATICS, Vol: 16, Pages: 1280-1301, ISSN: 1464-7141

JOURNAL ARTICLE

Aisopou A, Stoianov I, Graham N, Karney Bet al., 2014, Analytical and experimental investigation of chlorine decay in water supply systems under unsteady hydraulic conditions, JOURNAL OF HYDROINFORMATICS, Vol: 16, Pages: 690-709, ISSN: 1464-7141

JOURNAL ARTICLE

Wright R, Stoianov I, Parpas P, 2014, Dynamic topology in water distribution networks, 12th International Conference on Computing-and-Control-for-the-Water-Industry (CCWI), Publisher: ELSEVIER SCIENCE BV, Pages: 1735-1744, ISSN: 1877-7058

CONFERENCE PAPER

This data is extracted from the Web of Science and reproduced under a licence from Thomson Reuters. You may not copy or re-distribute this data in whole or in part without the written consent of the Science business of Thomson Reuters.

Request URL: http://wlsprd.imperial.ac.uk:80/respub/WEB-INF/jsp/search-html.jsp Request URI: /respub/WEB-INF/jsp/search-html.jsp Query String: respub-action=search.html&id=00170624&limit=30&person=true