Conferences, Lectures, & Seminars
Events for December
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MULTISCALE RELATIONSHIPS BETWEEN FRACTURE LENGTH...
Mon, Dec 01, 2008 @ 02:00 PM - 03:00 PM
Sonny Astani Department of Civil and Environmental Engineering
Conferences, Lectures, & Seminars
... APERTURE, DENSITY AND PERMEABILITYby:Dr. Shlomo P. NeumanDepartment of Hydrology and Water ResourcesUniversity of Arizona, Tucson, Arizona 85721ABSTRACT:Fractured rocks exhibit a hierarchical structure which renders their attributes scale-dependent. In particular available data indicate a tendency for fracture length scales to be distributed according to a power law, average fracture aperture to be given by a power of the fracture length scale, and fracture density as well as log permeability to behave as random fractals. To date, no consistent theoretical relationship has been developed between fracture type (as categorized, for example, by length scale and/or aperture) and corresponding fractal attributes (such as density and log permeability). We explore multiscale relationships between these fracture categories and attributes on the basis of a theory recently proposed by Neuman (2003), which allows linking them in a formal way. Analyzing the available data in light of this theory allows us to demonstrate that, for fractures having length scale L, (a) the variance of any fractal attribute grows as a positive power of L, (b) the same variance decreases as a negative power of the smallest length scale sampled, (c) for nominal parameters that are most representative of values inferred from field data, the variance of fracture densities increases quadratically with L, rendering their standard deviation linearly proportional to L, (d) for such nominal parameters log permeability variance increases as , (e) for a given L the variance of log permeability is proportional to that of fracture density, the constant of proportionality being a (positive, zero or negative) power of L, and (f) the standard deviation of log permeability is proportional to a positive power of the average aperture, where . The underlying theory contains explicit expressions for the mean, variance, variogram and integral (spatial correlation) scale of a statistically anisotropic fractal attribute truncated by upper and lower length scale cutoffs and/or internal lacunae. The attribute may have a Gaussian distribution, in which case it forms fractional Brownian motion (fBm), or a zero-mean symmetric Levy stable distribution, in which case it forms fractional Levy motion (fBm), the latter distribution exhibiting heavier tails than does the former. Our expression for the mean attribute of a truncated hierarchy of fracture length scales, in terms of the mean attributes associated with individual scales, may yield meaningful representations of the overall density or porosity of a truncated fracture hierarchy. However, it generally does not yield equivalent or effective values of permeability. Instead, the latter are defined on the basis of equivalent or effective forms of Darcy's law the derivation of which typically requires simulating fluid flow through the hierarchy. We mention briefly the effective permeability of a box embedded in a hierarchical medium, and associated measures of uncertainty, develop by Di Federico et al. (1999) on the basis of the scaling theory on which this talk is partly based. Based on Neuman, S.P., Multiscale relationships between fracture length, aperture, density and permeability, Geophys. Res. Lett., L22402, doi:10.1029/2008GL035622, 2008.
Location: Kaprielian Hall (KAP) - 209
Audiences: Everyone Is Invited
Contact: Evangeline Reyes
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FIELD AND LABORATORY ANALYSIS OF WATER WELL DESIGN PARAMETERS
Wed, Dec 10, 2008 @ 09:00 AM - 12:00 PM
Sonny Astani Department of Civil and Environmental Engineering
Conferences, Lectures, & Seminars
PhD Oral Defense by:Christopher Harich
Graduate StudentAbstract:
It is the goal of this research to establish fundamental principles of water well design. These principles have developed critical water well design parameters for four different types of aquifers; very coarse, coarse, medium and fine grained according to the Wentworth classification. With extensive laboratory testing utilizing the world's largest sand-tank well/aquifer model at the University of Southern California's Geohydrology Laboratory and field data from over 100 wells accompanied by 400 aquifer sieves, this research has developed a standard by which water wells can be designed.
The design of efficient water wells requires knowledge of various hydraulic factors that affect the major drawdown components of a well. The Step Drawdown Method has been shown to be a valid more robust method for the determination of water well efficiency. This method determines more head loss terms then the Conventional Method for calculating well efficiency and thus determines all of the aquifer and well loss terms for a particular well. The demarcation of the transitional state of laminar to turbulent flow is well defined by the method of critical radius and presented herein. Five types of initial well developments are discussed and are critical to decreasing the critical radius over a well's operational pumping rate. Minimizing these turbulent flow losses can result in substantial cost savings over the lifetime of the well.
This research has will aid engineers in developing more efficient water wells in various geohydrological settings. Its goal is to provide the largest production of water while maintaining the lowest operational costs for the well owners. This paper will design wells that are simple and strong while protecting our water resources.Location: Kaprielian Hall (KAP) - 209
Audiences: Everyone Is Invited
Contact: Evangeline Reyes
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A Functional Genomics Approach for Improving ....
Tue, Dec 16, 2008 @ 02:00 PM - 03:00 PM
Sonny Astani Department of Civil and Environmental Engineering
Conferences, Lectures, & Seminars
Chlorinated Organic Bioremediation ProcessesDr. David R. JohnsonPostdoctoral ResearcherDepartment of Fundamental MicrobiologyUniversity of Laussane, SwitzerlandAbstract:Chlorinated organics are among the most prevalent contaminants of groundwater resources and pose a significant threat to human and ecological health. Remediating these resources with pump-and-treat strategies is technically challenging and costly. Fortunately, strategies that utilize microorganisms to degrade these pollutants in situ have been developed and applied with success. Of particular interest are members of the Dehalococcoides group of bacteria because of their ability to degrade a wide range of chlorinated organic pollutants. Although significant progress has been made, effective methods for optimizing and monitoring the performance of Dehalococcoides-based bioremediation systems are now needed.To begin to address these needs, this research applied functional genomics tools to improve our understanding of the model bacterium Dehalococcoides ethenogenes strain 195. Transcriptomics were analyzed by whole-genome microarrays while proteomics were analyzed by liquid chromatography coupled with tandem mass spectrometry. Active and non-active cultures were characterized and compared to identify factors that can potentially limit dechlorination performance. This approach successfully identified cobalamin (vitamin B12) as a key factor controlling dechlorination activity and revealed novel strategies for minimizing cobalamin deficiencies within bioremediation systems. In addition, these studies identified mRNA and peptide biomarkers that could be used to quantitatively assess the physiological state of strain 195 within uncharacterized systems. The results of this research demonstrate the utility of functional genomics approaches for accelerating our understanding of environmental biological systems. More collaborative efforts between the fields of genome sciences and environmental engineering are now needed to help address current and future environmental problems.
Location: Kaprielian Hall (KAP) - 209
Audiences: Everyone Is Invited
Contact: Evangeline Reyes
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Title Seismic Performance and Post-Earthquake Resilience of Highway Systems
Wed, Dec 17, 2008 @ 02:00 PM - 03:00 PM
Sonny Astani Department of Civil and Environmental Engineering
Conferences, Lectures, & Seminars
Speaker: Stu Werner Seismic Systems & Engineering Consultants, Oakland CA Abstract: Protection of life safety is no longer the sole requirement for the successful seismic design of bridges and other highway structures. Design to maintain acceptable highway-system performance and resilience that reduces post-earthquake traffic disruptions and ensures rapid restoration of traffic flows is also vital for facilitating emergency response, reducing economic losses, and reducing socio-economic impacts of earthquake damage. This presentation will address this issue, which is now being investigated under a new research project that is part of a continuation of the multi-year FHWA Seismic Research Program. The presentation will also describe the REDARS methodology and software for seismic risk analysis of highway systems, its application to the assessment of highway-system performance and resilience, and future directions for its continued development.Duration About 40-45 minutes for presentation, plus time for questions and discussionBio. Stu Werner has over 40 years of experience in earthquake engineering and risk analysis of highway, seaport, and air transportation systems and structures. His work in this area has included design peer review, analysis, full scale testing, and system risk analysis for diverse clients that have included the Federal Highway Administration, Caltrans, Port of Los Angeles, Port of Oakland, BART, San Francisco Airport, US Geological Survey, FEMA, CH2M Hill, URS, and Oregon DOT. Since the mid-1990s, Stu has led the development of REDARS and its application to highway systems in earthquake-prone regions nationwide. He is president of Seismic Systems & Engineering Consultants in Oakland CA, has published over 130 papers that describe his various earthquake engineering activities, and is a recent recipient of the ASCE C. Martin Duke award in recognition of his contributions to the advancement of lifeline earthquake engineering.
Location: Kaprielian Hall (KAP) - 209
Audiences: Everyone Is Invited
Contact: Evangeline Reyes