Civil and Environmental Engineering SEMINAR SERIES
Jesse B. Hoagg
Postdoctoral
“Discrete-Time Adaptive Control Using a Retrospective Performance
and its Applications to Structures and Fluids”
12:00 – 1:00 pm
WEDNESDAY
October 21, 2009
CIEMAS Auditorium, Side A
Abstract
Adaptive control is an area of control theory focused on achieving control objectives when limited model information is available or models are highly uncertain. Most adaptive control techniques rely on restrictive plant assumptions, requiring, for example, that plants are minimum phase or open-loop stable, and have low relative degree. This seminar is focused on an adaptive control technique, namely, retrospective cost adaptive control, that can control plants that are minimum phase or non-minimum phase, open-loop stable or unstable, and have arbitrary relative degree. Retrospective cost adaptive controllers are designed by minimizing a retrospective performance function, which is a surrogate for a system’s true performance measurement. Retrospective cost adaptive control can be used for a variety of control objectives including stabilization, command following, and disturbance rejection. Notably, these adaptive controllers can follow deterministic commands and reject deterministic disturbances without knowledge of the command or disturbance spectrum.
This seminar will present the existing theory behind retrospective cost adaptive control. We’ll begin by presenting the adaptive law for single-input, single-output, minimum-phase systems. Next, we’ll extend the controller to handle non-minimum-phase zeros. Finally, we’ll cover the full multi-input, multi-output control problem for plants that are either minimum phase or non-minimum phase. Retrospective cost adaptive control has been demonstrated on applications including the Air Force’s deployable optical telescope test bed, flow control using computational fluid dynamics, and a test bed for flexible membrane control. The results of these applications will be shared.
Bio
Jesse Hoagg is currently a Postdoctoral Research Fellow in the Aerospace Engineering Department at the
Department of Civil & Environmental Engineering
Vanderbilt University
Nashville, TN
"Reliability Analysis and Optimization Under Uncertainty"
12:00-1:00pm
September 16, 2009
CIEMAS Auditorium, Side A
Abstract
This talk will present recent methods to address several challenges in model-based reliability analysis for the performance evaluation of engineering systems. Model-based simulation becomes attractive for systems that are too large and complex for full-scale reliability testing. The approach also facilitates efficient strategies for optimization with reliability constraints, especially for multi-disciplinary systems. The optimization could be related to design, operations, life cycle cost or risk management.
However, model-based reliability analysis and optimization involve many approximations and assumptions, and thus confidence in the simulation result is an important issue. Sources of uncertainty are both aleatory and epistemic, stemming from natural variability, information uncertainty, and modeling errors. Recent research on methods for model validation and model calibration will be discussed. This includes methods for quantifying various errors and uncertainties, including model form uncertainty; and methods for uncertainty reduction and extrapolation to usage conditions different from laboratory conditions. These techniques will be illustrated with applications to mechanical systems fatigue/fracture modeling and structural health monitoring (diagnosis and prognosis).
Department of Civil & Environmental Engineering
Seminar
Lauren Greenlee
University of Texas, Austin
Thursday, April 23
12:00-1:00pm
Teer 203
In many locations, fresh water resources are insufficient for local needs, and alternative sources with lesser water quality are being considered as drinking water supplies. In particular, the
In brackish water RO systems, recovery is limited by salt precipitation. Chemicals called antiscalants are used to complex with problematic salts (CaCO3, CaSO4, BaSO4, SrSO4, silica), delaying precipitation. However, salt concentration increases with recovery, and eventually precipitation control is overcome. To increase system recovery and decrease the concentrate volume, a new approach is required. This research has focused on the development of a novel three-stage process to treat the concentrate from a brackish water RO system. The process achieves problematic salt removal through (I) antiscalant deactivation, (II) precipitation, and (III) solid/liquid separation. Antiscalant deactivation is performed using ozone (O3) and hydrogen peroxide (H2O2). pH elevation is used to precipitate salts, and solid/liquid separation is achieved through sedimentation and filtration. Results show that the treatment process allows removal of a significant portion (>80%) of the calcium present in the RO concentrate. The treated concentrate would be returned to the RO system for further treatment, and the process could increase overall recovery by at least 8% - 10%.
Duke University
Civil and Environmental Engineering
Seminar
Gregory W. Characklis
Associate Professor
Dept. of Environmental Sciences and
“Using Engineering and Economics to Improve
Water Resource Management”
12:00 – 1:00 pm
WEDNESDAY
April 8, 2009
Schiciano Auditorium, Side B
Population growth and economic development continue to drive increasing demand for water, while the costs and regulatory hurdles associated with developing new supplies have risen steadily. Consequently, a growing number of regions facing serious water resource challenges, challenges that may become increasingly complex if climate change induces significant variations in the hydrologic cycle. Improved strategies for managing existing water resources and developing new supplies will be required if society is to reliably meet its demand in a manner that is cost effective and more environmentally sustainable. More sophisticated planning approaches can benefit from the development of models that couple both the hydrologic and economic elements of water resource systems, particularly if these models also incorporate consideration of engineering and risk management principles.
Following an introduction to some of the primary forces affecting water resource management in the
“Investigations Into Nanoparticle
Chemistry in the Atmosphere”
12:00 – 1:00 pm
WEDNESDAY
March 4, 2009
Teer 203
Nanoparticle chemistry encompasses a broad range of topics, including nucleation phenomena, gas-surface and multiphase reactions, photochemistry, as well as an intricate array of organic and inorganic reactions. Heterogeneous reactions, in particular gas-surface reactions, are central to a number of environmental and technological processes: catalysis, corrosion, and ozone depletion to name a few. In the first part of the talk, we will discuss the kinetics of the HNO3 + NaCl reaction in the context of the tropospheric ozone budget. The second part of the talk will cover our research program in the atmospheric fate of engineered nanoparticles and their impact on the local atmospheric chemistry. Specifically, the chemical kinetics of engineered nanomaterial atmospheric transformations with common reactive gases will be discussed. We will also cover how engineered nanoparticles may behave as seed for secondary organic aerosol reactions.
Michael P. Tolocka holds an appointment as a graduate faculty member at the state of
Former Assistant Secretary of Energy for Environmental Management
Nuclear Facilities:
12:00-1:00pm
WEDNESDAY
February 18, 2009
CIEMAS Auditorium Side BThe United States Government, through the U.S. Department of Energy, has several ongoing programs involved with nuclear energy and nuclear research. The Environmental Management program, a $6 billion per year program employing about 34,000 people, currently operates nuclear facilities at a variety of locations across the country, and has capital construction projects for nuclear facilities ranging in estimated cost from $500 million to $12.2 billion, ongoing at five locations. This seminar will highlight successes, lessons learned and challenges for civil engineers who are or will be engaged in planning, engineering, construction and management of nuclear facilities. In particular, Mr. Rispoli will draw on recent first-hand experiences to present and discuss real projects, and his perspectives on how civil engineers and colleagues in related disciplines can contribute to future success in the nation’s nuclear projects.
Prof. Dionysios D. Dionysiou
Department of Civil and Environmental Engineering
University of Cincinnati
Seminar: February 5, 2009
Teer 203
1:00 - 2:00pm
Advanced Oxidation Technologies and Nanotechnologies for Water Treatment: Fundamentals, Development and Application Case study in the Destruction of Cyanotoxins
ABSTRACT: The enormous diversity of toxic and organic pollutants of different chemical composition eliminates the possibility of using a universal treatment method and has led to the development of special treatment methods for water decontamination. The so-called Advanced Oxidation Technologies (AOTs) and Nanotechnologies (AONs) are among the most promising emerging chemical oxidation processes and are anticipated to play a crucial role in water treatment as stand-alone processes or in combination with conventional technologies. Among AONs, TiO2 photocatalysis is of particular interest because of environmentally friendly features. TiO2 photocatalysis is characterized by a specific oxidation pathway, which includes the formation of hydroxyl radicals (?OH) or other powerful oxidizing species. The hydroxyl radicals are extremely reactive and readily attack most organic contaminants. As a result, the organic contaminants are sequentially transformed to simpler organic molecules that are eventually mineralized to CO2, H2O, and mineral species (i.e., Cl). In general, due to rapid hydroxyl-radical-based oxidation reactions, AONs are characterized by high reaction rates and short treatment times.
Dr. Dionysiou will discuss some general aspects of AOTs, Environmental Nanotechnology (fundamentals, applications), and specific examples of destruction of organic contaminants using hydroxyl radicals as well as TiO2-based AONs for the treatment and purification of water in general and in particular for the destruction of cyanobacterial toxins. He will discuss the development of a TiO2 photocatalytic technology using nanotechnology and self-assembling strategies. Results will also be presented on the synthesis of TiO2 catalyst in the form on films, and membranes and the application of these materials on the destruction of microcystin-LR, a potent, and most widely found cyanotoxin.
“The Elasticity of Elasticity” or “What Are Fluids and How Do We Model Them?”
Kumbakonam Rajagopal
Forsyth Chair Professor of Mechanical Engineering
Professor of Mathematics
Texas A&M University
Lunch: 12:00, Seminar 12:30 CIEMAS Auditorium ”B”
Abstract: Concepts such as a fluid and a solid are not as clear and unequivocal as their usage suggests. After a discussion of why most definitions that are used, from the most elementary to sophisticated mathematical definitions based
on symmetry groups, are to- tally inadequate, a rationale is presented for characterizing fluid-like and solid-like behavior. Then, several generalizations of the usual Navier-Stokes model that forms a cornerstone of fluid mechanics are discussed. Some views of the pioneers of fluid mechanics that have not been given the attention that they deserve are presented. Contrary to ideas that stem from the works of Bernoulli, DAlembert and Lagrange which have become entrenched in mechanics with regard to the determination of the constraint response, which do not allow for the possibility of the material moduli to depend on the Lagrange multiplier that enforces the constraint, an idea introduced by Gauss for describing the mechanics of rigid body is introduced and then generalized and its implications with regard to the modeling of fluids wherein the material moduli can depend on the Lagrange multiplier are discussed. The classical Navier-Stokes model is a special subcase of the class of models that are developed. The versatility of such models and their implications are outlined.
"Abnormal Loads and Progressive Collapse Assessment and Mitigation of Risk"
Bruce R. Ellingwood, Ph.D., P.E.
The Raymond Allen Jones Chair
College of Engineering Distinguished Professor
School of Civil and Environmental Engineering
Georgia Institute of Technology
Thursday, November 6, 2008
Lunch: 11:30, Seminar 12:00pm
Teer 203
local structural failure and propagates, by a chain reaction mechanism,
into a failure that involves a major portion of the structural system and
is disproportionate to the local initiating damage. Such collapses can
initiate as a result of extreme environmental or abnormal loads or
design/construction errors. Public awareness of building safety issues has
increased markedly in recent years as a result of well-publicized natural
and man-made disasters. Improved building practices and design procedures
to control the likelihood of such progressive failures are receiving
heightened interest from standards organizations and structural engineers
in the United States and elsewhere. Procedures for assessing the
vulnerability of buildings to such occurrences and for designing structural
systems to withstand local damage without subsequent development of a
general structural collapse can be developed using concepts of risk and
structural reliability analysis and probability-based limit states design.
The presentation summarizes design strategies to minimize the likelihood of
progressive collapse, and prospects for the implementation of general
provisions in national standards such as ASCE Standard 7, Minimum design
loads for buildings and other structures.
Erik Johnson, University of Southern California
Wednesday, November 12, 2008
Seminar 12:30-1:30p
CIEMAS Auditorium, Side B
Lunch to be served in the prefunction area at noon.
Structural health monitoring (SHM) seeks to use sensors to automate the process of damage detection in structures, whether damage due to natural hazards such as earthquakes or long-term degradation due to environment and aging. Significant research efforts have been focused on this topic in the last decade or two, with particular focus recently on new sensor technologies. However, the accuracy of most damage detection methods is strongly affected by consistency in the environmental conditions. The NEES Soil-Foundation-Structure-Interaction facility is used to study the effect of various environmental conditions, including temperature and moisture, on structural parameter identification. While temperature effects have been well identified by others, this study demonstrates significant dependence on the level of the water table in the soil.
A structural parameter identification method is developed based on a substructuring approach where a structural control system can be directly integrated to provide more accurate estimates of structural parameters. These estimates can, then, give more accurate characterization of structural damage as well as provide more accurate description of dynamic characteristics so that structural control can be more effective in mitigating damage from future natural hazards. This approach capitalizes on the synergies between structural control and structural health monitoring.
MEASUREMENT AND MODELING OF REAL-WORLD ACTIVITY, FUEL USE, AND EMISSIONS OF ONROAD AND NONROAD VEHICLES: A COMPARISON OF B20 BIODIESEL AND PETROLEUM DIESEL
H. Christopher Frey
Department of Civil, Construction, and Environmental Engineering
North Carolina State University
Campus Box 7908
Raleigh, NC 27695-7908
frey@ncsu.edu
The transportation sector accounts for one-fifth of U.S. national energy use and contributes significantly to national emissions of greenhouse gases, nitrogen oxides (NOx), carbon monoxide (CO), hydrocarbons (HCs) and particulate matter (PM). In other countries, such as China, mobile source energy use and emissions are growing rapidly. Mobile source emissions are typically estimated based on chassis or engine dynamometer data. Portable emission measurement systems (PEMS) enable real-world, in-use measurement of the activity, energy use, and emissions of a wide variety of vehicles. We have used PEMS to characterize a wide range of onroad and nonroad vehicles. These new data provide insight regarding approaches for improving energy efficiency and reducing emissions for mobile sources. For example, improved arterial signal timing and coordination can reduce light duty vehicle emissions by 10 to 20 percent. Relieving congestion can reduce emissions by as much as 50 percent. These measures will also improve fuel economy. Here, we focus on evaluation of the energy and emission implications of switching from petroleum diesel to soy-based B20 biodiesel. The U.S. Environmental Protection Agency (EPA) reported in 2002 that B20 leads to a 2 to 3 percent increase in tailpipe NOx emissions. Because NOx is a precursor to formation of tropospheric ozone, a respiratory irritant, there has been some resistance to adoption of biodiesel, even though the use of B20 significantly reduces emissions of CO, HC, and PM. Based on field measurements of 12 dump trucks, 8 cement mixers, and 15 construction vehicles, consistent reductions in tailpipe NOx emissions were observed, as well as 16 to 25 percent reductions in emissions of PM, CO, and HC. The differences in findings compared to EPA are attributed to fuel quality and real world duty cycles. A life cycle inventory (LCI) was used to estimate fuel cycle energy consumption and emissions of selected pollutants and greenhouse gases. Life cycle fossil energy reductions are estimated at 9 percent for B20 and 42 percent for B100 versus petroleum diesel based on the current national energy mix. These results have been used by fleet managers to make decisions regarding conversion of existing vehicles from petroleum diesel to biodiesel and provide critical information needed to inform the policy debate regarding biodiesel at local, regional, and national levels. A brief overview will also be given of related ongoing work pertaining to exposure and risk assessment for mobile and other sources.
Brief Biographical Sketch
H. Christopher Frey is a professor of environmental engineering in the Department of Civil, Construction, and Environmental Engineering at NC State. His research interests are measurement and modeling of real-world fuel use and emissions of onroad and nonroad vehicles; modeling and evaluation of advanced energy conversion (e.g., combustion, gasification) and environmental control systems; development and application of methods for quantification of variability and uncertainty and for sensitivity analysis in systems models; and exposure and risk analysis. He teaches courses in air pollution control, air quality, and environmental exposure and risk assessment. He has been the PI or Co-PI for over 40 research projects sponsored by the National Science Foundation, U.S. Environmental Protection Agency, U.S. Department of Agriculture, U.S. Department of Transportation, U.S. Department of Energy, NC Department of Transportation, and others. He currently serves on the U.S. Environmental Protection Agency’s Clean Air Scientific Advisory Committee (CASAC), an EPA Science Advisory Board panel on expert elicitation, a National Research Council committee on review of the toxicological assessment of tetrachloroethylene, and a NARSTO assessment of multipollutant air quality management. He has recently served on a World Health Organization working group on uncertainty in exposure assessment and was a lead author for guidance by the Intergovernmental Panel on Climate Change (IPCC) regarding uncertainty in greenhouse gas emission inventories. He is a Fellow and Past President of the Society for Risk Analysis and a Fellow of the Air & Waste Management Association. He has a B.S. Mechanical Engineering from the University of Virginia, and from Carnegie Mellon University he has a Master of Engineering in Mechanical Engineering and PhD in Engineering and Public Policy.
