Conferences, Lectures, & Seminars
Events for September
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Modeling complex urban systems
Thu, Sep 04, 2008 @ 02:00 PM - 03:00 PM
Sonny Astani Department of Civil and Environmental Engineering
Conferences, Lectures, & Seminars
Speaker:
Dr. Paul M. Torrens, Associate Professor, School of Geographical Sciences, Arizona State UniversityAbstract:
Urban simulations are an important toolkit for theorizing about cities, testing ideas and hypotheses, and evaluating plans and policies. As a field of research, urban modeling is at an important stage in its development. Urban simulations have, for a long time, grappled with the task of representing the rich complexity of cities as urban systems. The pace of urbanization and city growth, and the ever-increasing rate of adaptation of urban phenomena, have, to some extent, accelerated beyond the abilities of previous generations of modeling methodology to remain practically relevant and diagnostically useful. In response, older technologies based on automata have been retasked as agent-based models, capable of representing massive populations of dynamic and interactive actors, behaviorally, at atomic scales and characteristic times. Such tools may serve as a next generation of urban simulation methodology, but to do so, they must be successfully proven to engage with urban theory at small scales, large scales, and those in between. Urban simulation, as a field of research, is in its relative infancy in developing the rules and heuristics that can bridge large gaps between substantive understanding of how cities work on the ground and how those rich details might be represented in simulations. Datathe dearth of which has previously had a limiting influence on urban modelinghave begun to become available in larger volumes and with greater acuity, expanding our ability to satisfy urban models' voracious appetites for ground truth. Nevertheless, small-scale data that could be mapped to agent-based models are usually in piecemeal supply and existing dataware for calibrating and validating urban models is often out of touch with agent-based approaches.
This lecture will focus on my work in developing extensible, next generation simulation tools around the concept of geosimulation as a vehicle for building detailed behaviors into urban models, as well as my efforts to build innovative forms of dataware in support of dynamic, agent-based urban modeling, using space-time Geographic Information Systems and information visualization. I will discuss the novelty and usefulness of these approaches in theorizing about urban systems at many scales, through reference to applied models of suburban sprawl, residential mobility, community-level gentrification, and small-scale crowd dynamics in dense urban settings.Biography
Dr. Paul M. Torrens is an Associate Professor in the School of Geographical Sciences at Arizona State University and Director of its Geosimulation Laboratory. Paul is also an Affiliate in the University's Center for Social Dynamics and Complexity, as well as the GeoDa Center for Geospatial Analysis and Computation. Paul is Director of Geosimulation Labs, LLC, a research and development consultancy. His research is focused on Geographic Information Science and development of geosimulation and geocomputation tools, applied modeling of complex urban systems, and new emerging cyberspaces.
Paul holds a Ph.D. from University College London (2004), Master's degrees from Trinity College Dublin (1999) and Indiana University (1998), and a Bachelor's degree from Trinity College Dublin (1996). Paul has been an invited speaker at universities worldwide, from the University of Copenhagen and Trinity College Dublin to MIT, Cornell, and the University of Pennsylvania. He has given invited lectures and seminars to industry groups as diverse as the Institute for the Future, Microsoft, and France Telecom Orange. Paul has also presented invited talks at major technology conferences, from O'Reilly's Emerging Technology Conference to Where 2.0. He is a member of the Editorial Board of Computers, Environment and Urban Systems, and the International Journal of Microsimulation. His projects have been supported by the U.K. Economic and Social Research Council, the U.S. National Science Foundation, the Herberger Foundation, Science Foundation Arizona, Autodesk, Inc., and Alias Research. His research has been published widely and his work has featured in a diverse array of outlets, from Vanity Fair and Il Corriere della Sera to Forbes and Discover Magazine. His work earned him a CAREER Award from the U.S. National Science Foundation in 2007. (See http://geosimulation.org for more details.)Location: Kaprielian Hall (KAP) - 209
Audiences: Everyone Is Invited
Contact: Evangeline Reyes
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Advances in Structural Dynamics and Earthquake Engineering
Fri, Sep 19, 2008 @ 08:00 AM - 05:00 AM
Sonny Astani Department of Civil and Environmental Engineering
Conferences, Lectures, & Seminars
A Special International Symposium on "Advances in Structural Dynamics and Earthquake Engineering" Will be hosted by the University of Southern California Viterbi School of Engineering on Friday, 19 September 2008. The symposium is being held in honor of Professor Ahmed M. Abdel-Ghaffar of the USC faculty. The Symposium is being held in Ronald Tutor Hall on the USC Campus near downtown Los Angeles. The event is scheduled from 8:00 A.M. to 5:00 P.M. and lunch will be served. Attendance at the Symposium is complementary and is open to everyone; however, reservations are required. Please contact Jennifer Cantwell (jenc@usc.edu) to confirm your attendance and to obtain further details.
Location: Ronald Tutor Hall, Room 526
Audiences: Everyone Is Invited
Contact: Jennifer Cantwell
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International Symposium on Advances in Structural Dynamics and Earthquake Engineering
Fri, Sep 19, 2008 @ 08:00 AM - 05:00 PM
Sonny Astani Department of Civil and Environmental Engineering
Conferences, Lectures, & Seminars
Type: LecturesDescription: An international symposium in honor of the late Professor Ahmed Abdel-Ghaffar. Lunch will be served. Attendance at the Symposium is complimentary and is open to everyone; however, reservations are required.Link: http://www.usc.edu/dept/civil_eng/dept/news/abdel-ghaffar-symposium/
Location: Ronald Tutor Hall, Room 526
Audiences: Everyone Is Invited
Contact: Evangeline Reyes
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Optimization and Uncertainty Analysis of .....
Wed, Sep 24, 2008 @ 03:00 PM - 04:00 PM
Sonny Astani Department of Civil and Environmental Engineering
Conferences, Lectures, & Seminars
Computationally Expensive Environmental Models Speaker:
Christine A. Shoemaker,
Joseph P. Ripley Professor,
School of Civil and Environmental Engineering and
School of Operations Research and Information Technology
Cornell University,
Abstract:Many important problems in engineering and science require optimization of computationally expensive (costly) functions. These applications include calibration of simulation model parameters to data and optimizing a design or operational plan to meet an economic objective. With costly functions (like nonlinear systems of partial differential equations), this optimization is made difficult by the limited number of model simulations that can be done because each simulation takes a long time (e.g. 10 minutes to many hours). The optimization problem is even more difficult if it has multiple local optima, thereby requiring a global optimization algorithm. Estimating the uncertainty associated with prediction of calibrated models based on the available data is even more computationally expensive.Computational efficiency is important because it is not feasible to make many thousands of simulations to do calibration and uncertainty analysis for computationally expensive models. Hence the purpose of this research is to make it feasible to do this analysis on environmental and watershed models that are computationally expensive because they incorporate spatial heterogeneity and more detail on hydrological and environmental processes over longer periods of time. The algorithms also apply to costly simulation models in other fields.Our algorithms use function approximation methods to approximate the objective function based on previous costly function evaluations. Our latest derivative-free algorithms are ORBIT (which is based on trust-region radial-basis function models) and GORBIT, which is an extension of ORBIT to global optimization. These algorithms perform very well in comparison to alternative algorithms if the number of simulations is limited. We have convergence proofs. Working with Prof. Ruppert's statistics group, we have also developed a method SOARS that expands the use of function approximation to Bayesian analysis (including MCMC) of uncertainty for costly functions. Numerical results for an environmental PDE problem demonstrated excellent accuracy and a 60-fold reduction in costly simulations with SOARS over that required for conventional MCMC analysis. I will also describe the application of SOARS to the 1200 km2 Cannonsville watershed. The results include a statistically rigorous analysis of multiple watershed model outputs and prediction intervals for future events.This presentation will summarize results from several papers that include work by S. Wild, D. Ruppert, N. Bliznyuk and D. Cowan.Location: Kaprielian Hall (KAP) - 209
Audiences: Everyone Is Invited
Contact: Evangeline Reyes
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DIFFRACTION OF SH-WAVES BY SURFACE OR SUB-SURFACE ...
Mon, Sep 29, 2008 @ 03:30 PM - 05:00 PM
Sonny Astani Department of Civil and Environmental Engineering
Conferences, Lectures, & Seminars
TOPOGRAPHIES WITH APPLICATION TO SOIL-STRUCTURE INTERACTION ON SHALLOW FOUNDATIONSOral Defense by:Hao LuoSonny Astani Department of Civil and Environmental EngineeringAbstract:Seismic response of local sites is a fundamental problem that has been broadly researched for decades. It is an essential step in evaluating maximum intensity of earthquake effects for a specified local site that might happen in the future considering the effects of local topography or various massive artificial structures, so it is crucial to seismic hazard, risk analysis, and earthquake microzonation. Seismic waves can be categorized into body waves and surface waves. Among the three types of body waves: P-, SV-, and SH-waves, the response of SH-waves, is restrained to the out-of-plane unidirection, thus is the most fundamental one and studied in this dissertation.
The objectives of this dissertation are: first, to explore diffraction of incident plane or cylindrical SH-waves by various topographies or underground irregularities; secondly, to investigate the Soil-Structure Interaction (S.S.I.) effects. Two-dimensional plane strain models studied are as diverse as ground surface irregularities (e.g., hills, canyons, canyons), geotechnical engineering (e.g., tunnels, underground cavities, excavations, foundations), and Soil-Structure Interaction models with non-, rigid, or flexible foundations. Although the geometries adopted in those models are relatively much simpler than the ones by numerical methods, the analytical solutions gained by these simple models are indispensable in verifying solutions by various numerical methods (e.g., Finite Element Method; Boundary Element Method). All the models attempted are sitting or encased in an elastic half-space. All the materials appeared are isotropic, homogeneous, and perfectly elastic.
Wave function expansion method is used for solving all the mathematical models in an analytical scheme. The model is computed by mathematically assembling different segments together on their interfaces adjacent to each other. Finally, the problem is reduced to solving a series of infinite linear equations. The governing finite linear equation systems after truncation via this way are always ill-conditioned that require carefully coped with to ensure the accuracy of solutions.
With the analytical solution attained, the response of displacement and stress along the free ground surface are discussed. Displacement and stress residues are calculated to verify the validity of those numerical results. Great effects on dynamic stress concentration and motion nearby due to the existence of those irregularities are expected and analyzed.Location: Kaprielian Hall (KAP) - 209
Audiences: Everyone Is Invited
Contact: Evangeline Reyes