Optimization Based Partitioning Selection for Improved Contaminant Detection Performance

Indoor Air Quality monitoring is an essential ingredient of intelligent buildings. The release of various airborne contaminants into the buildings, compromises the health and safety of occupants. Therefore, early contaminant detection is of paramount importance for the timely activation of proper contingency plans in order to minimize the impact of contaminants on occupants health. The objective of this work is to enhance the performance of a distributed contaminant detection methodology, in terms of the minimum detectable contaminant release rates, by considering the joint problem of partitioning selection and observer gain design. Towards this direction, a detectability analysis is performed to derive appropriate conditions for the minimum guaranteed detectable contaminant release rate for specific partitioning configuration and observer gains. The derived detectability conditions are then exploited to formulate and solve an optimization problem for jointly selecting the partitioning configuration and observer gains that yield the best contaminant detection performance

Stochastic Programming Approaches for the Placement of Gas Detectors in Process Facilities

The release of flammable and toxic chemicals in petrochemical facilities is a major concern when designing modern process safety systems. While the proper selection of the necessary types of gas detectors needed is important, appropriate placement of these detectors is required in order to have a well-functioning gas detection system. However, the uncertainty in leak locations, gas composition, process and weather conditions, and process geometries must all be considered when attempting to determine the appropriate number and placement of the gas detectors. Because traditional approaches are typically based on heuristics, there exists the need to develop more rigorous optimization based approaches to handling this problem. This work presents several mixed-integer programming formulations to address this need. First, a general mixed-integer linear programming problem is presented. This formulation takes advantage of precomputed computational fluid dynamics (CFD) simulations to determine a gas detector placement that minimizes the expected detection time across all scenarios. An extension to this formulation is added that considers the overall coverage in a facility in order to improve the detector placement when enough scenarios may not be available. Additionally, a formulation considering the Conditional-Value-at-Risk is also presented. This formulation provides some control over the shape of the tail of the distribution, not only minimizing the expected detection time across all scenarios, but also improving the tail behavior. In addition to improved formulations, procedures are introduced to determine confidence in the placement generated and to determine if enough scenarios have been used in determining the gas detector placement. First, a procedure is introduced to analyze the performance of the proposed gas detector placement in the face of “unforeseen” scenarios, or scenarios that were not necessarily included in the original formulation. Additionally, a procedure for determine the confidence interval on the optimality gap between a placement generated with a sample of scenarios and its estimated performance on the entire uncertainty space. Finally, a method for determining if enough scenarios have been used and how much additional benefit is expected by adding more scenarios to the optimization is proposed. Results are presented for each of the formulations and methods presented using three data sets from an actual process facility. The use of an off-the-shelf toolkit for the placement of detectors in municipal water networks from the EPA, known as TEVA-SPOT, is explored. Because this toolkit was not designed for placing gas detectors, some adaptation of the files is necessary, and the procedure for doing so is presented

An effective and efficient method for identification of contamination sources in water distribution systems based on manual grab‐sampling

This is the author accepted manuscript. The final version is available from American Geophysical Union via the DOI in this recordData Availability Statement: The data will eventually be deposited in the general repository Zenodo by the time the article is accepted, and the data are now available as Supporting Information for review purpose.Most of the contamination source localization methods for water distribution systems (WDSs) assume the availability of accurate water quality models and multi-parameter online sensors, which are often out of reach of many water utilities. To address this, a novel manual grab-sampling method (MGSM) is developed to effectively and efficiently locate continuous contamination sources in a WDS using a dynamic and cyclical sampling strategy. The grab samples are collected at a pre-specified number of hydrants by the corresponding teams followed by laboratory tests. The MGSM optimizes the sampling plan at each cycle by making the probability of contamination source(s) in each sub-network as equal as possible, where sub-networks are determined by the selected hydrants and current flow pipe directions. The CS's size is reduced at each cycle by exploiting sample testing results obtained in the previous cycle until there are no further hydrants to sample from. Two real-world WDSs are used to demonstrate the effectiveness of the proposed MGSM. The results obtained show that the MGSM can significantly reduce the spatial range of the CS (to about 5% of the entire WDS) for a range of scenarios including multiple contamination sources and pipe flow direction changes. We found that an optimal number of sampling teams exists for a given WDS, representing a balanced trade-off between detection efficiency and sampling/testing budgets. Due to its relative simplicity, the proposed MGSM can be used in engineering practice straightaway and it represents a viable alternative to the methods associated with water quality models and sensors.Excellent Youth Natural Science Foundation of Zhejiang Province, ChinaNational Natural Science Foundation of ChinaNational Natural Science Foundation of ChinaHong Kong Research Grants CouncilEuropean Research Counci

The 20th Annual International Conference on Soils, Sediments and Water

Conference at a Glance Monday, October 18, 2004 Workshops (Workshop #1: 9:00 am-5:00 pm, Workshops #2-3: 10:00 am-5:00 pm, Workshops #4-5: 1:00-5:00 pm, Workshop #6: 2:00-5:00 pm) Workshop #1: Modeling Vapor Attenuation Workshop: A Study of Vapor Intrusion Modeling in the Context of EPA’s Guidance Workshop # 2: Theory and Use of Field Portable X-ray Fluorescence for Soil Analysis Workshop #3: In-Situ Chemical Oxidation Workshop Workshop #4: The Triad Approach to Managing Decision Uncertainty for Better Cleanup Projects Workshops #5: The Role of Anaerobic Biodegradation Process in Passive and Enhanced Monitored Natural Attenuation Programs Workshop #6: Environmental Fate of Hydrocarbons in Soils and Groundwater Tuesday, October 19, 2004 Platform Presentations 8:30am – Noon Session 1: Environmental Biotechnology Session 2: Heavy Metals at Training Ranges Session 3: Site Assessment Session 4: Bioremediation of Acid Mine Drainage and Removal of Metals 1:30 – 5:30pm Session 1: Environmental Terrorism Session 2: Remediation I Session 3: Phytoremediation Session 4: Heavy Metals Poster Session 4:00 – 6:00pm Social 4:30 – 6:00pm. Exhibit Area, First Floor Campus Center Workshops (Evening, 7:00 – 10:00pm) Workshop #1: Modeling Vapor Attenuation Workshop: A Study of Vapor Intrusion Modeling in the Context of EPA’s Guidance (Continued) Workshop #7: Asbestos and the MCP Workshop #8: Policy Issues in Inter-Agency Coordination Workshop #9: In-Situ Thermal Remediation Wednesday, October 20, 2004 Platform Presentations 8:30am – Noon Session 1: In-Situ Chemical Oxidation Session 2: Oxygenates Session 3: Bioindicators/Biomarkers of Environmental Health: Concepts and Application Session 4: Pay-for-Performance Remediation Technologies - Methods & Case Studies of Science & Economics 1:30 – 5:30pm Session 1: Risk Assessment and Remedial Approaches Towards Restoration and Management of Contaminated Rivers Session 2: Arsenic Session 3a: Analysis Session 3b: Pesticides Session 3c: Indoor Air Session 4: Bioremediation Poster Session 4:00 – 6:00pm Social 4:30 – 6:00pm. Exhibit Area, First Floor Campus Center Workshops (Evening, 7:00 – 10:00pm) Workshop #10: An Introduction to the Use and Application of Gene Chips in Environmental Toxicology and Implications for Their Use as Biomarkers in Contaminated Sites Evaluations Workshop #11: Latest Developments in Managing Perchlorate in Soils and Groundwater Workshop #12: Vapor Intrusion into Indoor Air Workshop: MADEP Requirements, Background Levels, Case Studies and More Workshop #13: Exploring Innovative and Cost-Effective Solutions to Contaminated Sediments to Achieve Ecological Restoration of the Lower Neponset River Workshop #14: Environmental Forensics Workshop Thursday, October 21, 2004 Platform Presentations 8:30am – Noon Session 1: Environmental Forensics Session 2a: Legal Issues Session 2b: Modeling Session 3: Perchlorate Session 4: Risk Assessment and Bioavailability 1:30 – 5:30pm Session 1: Remediation II Session 2: Sediments Session 3: Regulator

The 22nd Annual International Conference on Soils, Sediments and Water

Conference at a Glance Monday, October 16, 2006 Workshop #1: 8:30am - 5:00pm Workshop #2: 9:00am - 5:00pm Workshop #3: 10:00am - 5:00pm Workshops #4, 5 & 6: 1:00pm - 5:00pm Workshop #10: 2:00 - 5:00pm Workshop #1: Evaluating Monitored Natural Attenuation of MTBE and TBA Workshop #2: Getting to Closure at LNAPL Sites Workshop #3: In-Situ Chemical Oxidation Workshop Workshop #4: The Role of Anaerobic Biodegradation Processes in Passive and Enhanced Monitored Natural Attenuation Programs Workshop #5: The 2006 MCP Audit- A Case Study Approach Workshop #6: Integrating the Remediation Strategy into the Lifecycle of a Contaminated Sediments Project Workshop #10: Environmental Fate of Hydrocarbons in Soils and Groundwater Tuesday, October 17, 2006 Morning 8:30am - 9:00am Conference Welcome and Overview 9:00am - Noon Sessions are concurrent Session 1: Risk Assessment Session 2: Site Assessment Session 3: Legal/Regulatory Session 4: Heavy Metals Session 5: Combining Chemical and Biological Technologies for Soil and Groundwater Remediation Afternoon 1:30pm - 5:30pm Sessions are concurrent Session 1: Environmental Biotechnology Session 2: Analysis Session 3: Ozone Remedial Barrier and Clean-up systems for Fuel and Solvent Spills Session 4: Emerging Contaminants Session 5: Phytoremediation Poster Session 4:00 - 6:00pm, Exhibit Area, First Floor, Campus Center Social 4:30-6:00pm, Exhibit Area, First Floor, Campus Center Workshops Evening, 7:00 - 10:00pm Workshop #7: Applied Chemical Fingerprinting in Environmental Forensics Workshop #8: In-Situ Thermal Remediation Wednesday, October 18, 2006 Morning 8:30am - Noon Sessions are concurrent Session 1: Environmental Benefits and Risks of Nanomaterials Session 2: Chemical Oxidation Session 3: Environmental Forensics *Session 4A: Oxygenates and Public Water Supplies *Session 4B: Evaluating and Management of Small Releases from USTs Afternoon 1:30pm - 5:30pm Sessions are concurrent Session 1: Remediation Session 2: Natural Resource Damage Assessments: Integrating Remediation and Restoration Session 3: Perchlorate *Session 4A: Oxygenate Biodegradation *Session 4B: Ethanol Fuels *Please note: Sessions 4A and 4Bmorning and afternoon will run concurrently with the other sessions, BUT the presentation times will not be the same as presentation times for Sessions 1, 2 and 3. Please consult the final program for presentation times Poster Session 4:00 - 6:00pm, Exhibit Area, First Floor, Campus Center Social 4:30-6:00pm, Exhibit Area, First Floor, Campus Center Workshops Evening, 7:00 - 10:00pm Workshop #9: Down-Gradient Property Status: Practices and Pitfalls Workshop #10 has been moved to Monday, October 16, 2006, from 2:00 - 5:00pm. Thursday, October 19, 2006 Morning 8:30am -Noon Sessions are concurrent Session 1: Vapor Intrusion Session 2: Implementing Aggressive Remediation Strategies Session 3: Bioremediation Session 4: Contaminated Sites Research in Canada & the Contaminated Sites Action Plan Afternoon 1:30pm – 5:30pm Sessions are concurrent Session 1: Sediments Session 2: Arsenic Session 3A: Brownfields Session 3B: Environmental Fate Session 4: Pesticide