| publications-3981 |
article |
2006 |
Carr, Robert D. and Greenberg, Harvey J. and Hart, William E. and Konjevod, Goran and Lauer, Erik and Lin, Henry and Lin, Henry and Lin, Henry and Morrison, Tod and Phillips, Cynthia A. |
Robust optimization of contaminant sensor placement for community water systems |
Mathematical Programming |
10.1007/s10107-005-0689-x |
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We present a series of related robust optimization models for placing sensors in municipal water networks to detect contaminants that are maliciously or accidentally injected. We formulate sensor placement problems as mixed-integer programs, for which the objective coefficients are not known with certainty. We consider a restricted absolute robustness criteria that is motivated by natural restrictions on the uncertain data, and we define three robust optimization models that differ in how the coefficients in the objective vary. Under one set of assumptions there exists a sensor placement that is optimal for all admissible realizations of the coefficients. Under other assumptions, we can apply sorting to solve each worst-case realization efficiently, or we can apply duality to integrate the worst-case outcome and have one integer program. The most difficult case is where the objective parameters are bilinear, and we prove its complexity is NP-hard even under simplifying assumptions. We consider a relaxation that provides an approximation, giving an overall guarantee of near-optimality when used with branch-and-bound search. We present preliminary computational experiments that illustrate the computational complexity of solving these robust formulations on sensor placement applications. |
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| publications-3982 |
article |
2005 |
LΓ³pez-Paredes, Adolfo and LΓ³pez-Paredes, Adolfo and SaurΔ±Μ, David and SaurΓ, David and GalΓ΅n, JosΓ© Manuel and GalΓ΅n, JosΓ© Manuel |
Urban Water Management with Artificial Societies of Agents: The FIRMABAR Simulator |
Simulation |
10.1177/0037549705053167 |
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In this article, the authors present an agent-based simulator for the integrated freshwater assessment in a geographical area. It has been developed and successfully applied to the metropolitan region of Barcelona, and it is currently applied to the metropolitan area of Valladolid. Such simulator provides the policy makers with an additional tool to evaluate alternative water policies in different scenarios. The design and the validation of the model are based on participatory processes with a platform of the representative stakeholders. |
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| publications-3983 |
article |
2009 |
Parks, Shannon and Parks, Shannon L. Isovitsch and VanBriesen, Jeanne M. and VanBriesen, Jeanne M. |
Booster Disinfection for Response to Contamination in a Drinking Water Distribution System |
Journal of Water Resources Planning and Management |
10.1061/(asce)0733-9496(2009)135:6(502) |
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Booster disinfection has been shown to be an effective means of maintaining more stable chlorine residuals in a water distribution system. It has been suggested that booster disinfection could also be a viable means of protecting a population against contamination. We simulated random contamination events in a model water distribution system with an optimized sensor network. A disinfection boost was simulated to begin the instant the contamination reached a sensor, and a range of decay coefficients were applied to the contaminant to simulate reaction with the disinfectant. Cumulative distribution curves of the volume of consumed contaminated water for various response levels were prepared to analyze how each response affected the vulnerability of the system. This analysis illustrated that a boost-response system could be effective in significantly reducing the volume of consumed contaminated water, but only in very specific circumstances. Most importantly, the booster must be located at a node with high r... |
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| publications-3984 |
article |
2008 |
Cristo, Cristiana Di and Leopardi, Angelo |
Pollution Source Identification of Accidental Contamination in Water Distribution Networks |
Journal of Water Resources Planning and Management |
10.1061/(asce)0733-9496(2008)134:2(197) |
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In the present technical note, a simple methodology for identifying the source location of an accidental contamination in a water distribution network is formulated. Starting from measured solute concentration data and using the pollution matrix concept, the methodology first selects a group of candidate nodes, which are possible intrusion points. Among all candidate nodes, the source location is then identified, minimizing the differences between simulated and measured concentrations. The source location procedure, which incorporates a hydraulic network simulation model, is formulated as an optimization problem, linearized using the water fraction matrix concept. An example illustrates methodology effectiveness. An uncertainty analysis is performed in order to demonstrate the methodology robustness with respect to uncertainties in some input data, like concentration measurements and water demands. |
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| publications-3985 |
article |
2012 |
Liu, Li and Zechman, Emily M. and Mahinthakumar, Gnanamanikam and Ranjithan, S. Ranji |
Coupling of logistic regression analysis and local search methods for characterization of water distribution system contaminant source |
Engineering Applications of Artificial Intelligence |
10.1016/j.engappai.2011.10.009 |
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| publications-3986 |
article |
1998 |
Kessler, Avner and Ostfeld, Avi and Sinai, Gideon |
Detecting Accidental Contaminations in Municipal Water Networks |
Journal of Water Resources Planning and Management |
10.1061/(asce)0733-9496(1998)124:4(192) |
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A methodology for finding the optimal layout of a detection system in a municipal water network is formulated and demonstrated. The detection system considered consists of a set of monitoring stations aimed at detecting a random external input of water pollution. The level of service provided to the consumers is defined by the maximum volume of consumed polluted water prior to detection. The methodology involves the establishment of an auxiliary network that represents all possible flow directions for a typical demand cycle, an β€_x009c_all shortest pathsβ€_x009d_ algorithm to identify domains of pollution, and a β€_x009c_set coveringβ€_x009d_ algorithm to optimally allocate the monitoring stations. The algorithm outcome is a minimal set of monitoring stations that satisfies a given level of service. The methodology is demonstrated on a small illustrative case and on a midsize water network. |
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| publications-3987 |
article |
2015 |
Pasqualetti, Fabio and Pasqualetti, Fabio and Dörfler, Florian and Dorfler, Florian and Bullo, Francesco and Bullo, Francesco |
Control-Theoretic Methods for Cyberphysical Security: Geometric Principles for Optimal Cross-Layer Resilient Control Systems |
IEEE Control Systems Magazine |
10.1109/mcs.2014.2364725 |
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Cyberphysical systems integrate physical processes, computational resources, and communication capabilities. Cyberphysical systems have permeated modern society, becoming prevalent in many domains, including energy production, health care, and telecommunications. Examples of cyberphysical systems include sensor networks, industrial automation systems, and critical infrastructures such as transportation networks, power generation and distribution networks, water and gas distribution networks, and advanced manufacturing systems. The integration of cybertechnologies with physical processes increases system efficiencies and, at the same time, introduces vulnerabilities that undermine the reliability of critical infrastructures. As recently highlighted by the Maroochy water breach in March 2000 [1], multiple recent power blackouts in Brazil [2], the SQL Slammer worm attack on the Davis-Besse nuclear plant in January 2003 [3], the StuxNet computer worm in June 2010 [4], and various industrial security incidents [5], cyberphysical systems are prone to failures and attacks on their physical infrastructure and cyberattacks on their data management and communication layer [6], [7]. |
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| publications-3988 |
article |
2009 |
Huang, Jinhui Jeanne and McBean, Edward A. |
Data mining to identify contaminant event locations in water distribution systems. |
Journal of Water Resources Planning and Management |
10.1061/(asce)0733-9496(2009)135:6(466) |
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To respond to growing concerns related to potential contamination ingress via backflow and/or terrorist threats to drinking water, a data mining approach is developed. Use of this data mining approach, in conjunction with a maximum likelihood procedure provides the means to identify the location and time of an intrusion event, based on limited sensor data. Uncertainties in water demand, sensor measurement, and modeling, are demonstrated to be highly relevant and necessary to be considered in the contamination identification problem. The effectiveness of the data mining method is demonstrated using a case study network where it takes only 3 min to identify a multiple injection event using five sensors in a 285 node water distribution network, including consideration of the aforementioned sources of uncertainty. The effectiveness of the method ensures the ability for a rapid-response to an abnormal event, and consequently, minimizes exposure risks of water consumers. |
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| publications-3989 |
article |
2005 |
Laird, Carl D. and Laird, Carl D. and Biegler, Lorenz T. and van Bloemen Waanders, Bart G. and Bartlett, Roscoe A. |
Contamination Source Determination for Water Networks |
Journal of Water Resources Planning and Management |
10.1061/(asce)0733-9496(2005)131:2(125) |
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We formulate and solve an estimation problem for identifying both the time and location of contamination sources in municipal water networks using concentration measurements from a sparse sensor grid. Previous work showed that the direct sequential approach was insufficient to solve the time-dependent problem. Instead, a direct simultaneous approach is used, converging the network model and optimization problems simultaneously. An origin tracking algorithm is presented to reformulate the pipe expressions and characterize the time delays associated with network pipes. This algorithm removes the need to discretize along the length of the pipes and is efficient for large networks with many source and output nodes. The solution of the resulting nonlinear program provides the complete time-dependent injection profiles, identifying both the time and location of potential contamination sources. The effectiveness of this formulation is demonstrated on a network model for a real municipal water network. |
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| publications-3990 |
article |
2006 |
Guan, Jiabao and Aral, Mustafa M. and Maslia, Morris L. and Maslia, Morris L. and Grayman, Walter M. |
Identification of Contaminant Sources in Water Distribution Systems Using Simulation-Optimization Method: Case Study |
Journal of Water Resources Planning and Management |
10.1061/(asce)0733-9496(2006)132:4(252) |
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In this paper, the authors propose a new approach, the simulation–optimization method, to solve a nonlinear contaminant-source and release-history identification problem for a complex water distribution system. This approach is based on optimization analysis, using the EPANET water distribution system model as a simulator. In this approach, EPANET is used to generate concentrations at arbitrarily selected monitoring locations by specifying release histories of potential contaminant sources that are arbitrarily located within the water distribution system. This information is used in a continuous optimal predictor–corrector algorithm to identify the sources and their release histories. Throughout the simulation sequence, the water distribution system being studied is assumed to operate under known hydraulic operational patterns. The optimization model that is used as a corrector to estimate the release histories of the contaminant sources is designed to identify the similarity between the simulation respon... |
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