Time filter

Source Type

Columbia, United States

Bulut Y.,Paul C. Rizzo Associates | Bayat O.,Istanbul Kemerburgaz University
Conference Proceedings of the Society for Experimental Mechanics Series | Year: 2012

In the classical Kalman filter theory, one of the key assumptions is that a priori knowledge of the system model, which represents the actual system, is known without uncertainty. Our focus in this research is to estimate the state of a system that is subjected to stochastic disturbances by using an erroneous model along with the available stored measurements. We examine two approaches that take the effects of uncertain parameters into the account since these uncertain parameters degrade the estimate of the state. In the first approach, the errors in the nominal model, which are approximated by fictitious noise and covariance of the fictitious noise, are computed by using stored data. It is premised that the norm of discrepancy between correlation functions of the measurements and their estimates from the nominal model is minimum. The second approach involves the identification of a Kalman filter model on the premise that the norm of discrepancy between the measurements and their estimates is minimum. This paper reviews the two approaches and illustrates their performances numerically. © The Society for Experimental Mechanics, Inc. 2012.

Johnson W.J.,75 Center Road | Johnson M.G.,Rhea Engineers and Consultants | Zullo E.G.,Paul C. Rizzo Associates
Geotechnical Special Publication | Year: 2010

Ground fissuring at playa lakes is a common geohazard where differential settlement of aquifer sediments caused by groundwater extraction is considered to be the mechanism for fissure development. Although this mechanism may be a common problem, fissures may also originate from natural causes, including desiccation or tectonic movements. Broadwell Basin near the town of Ludlow, in San Bernardino County, California contains a narrow playa lake approximately four miles long and a mile wide that was considered as a site for possible industrial development. The location is isolated and not subject to groundwater extraction, but the lake bed contains numerous fissures that could be as wide as about 1.8 meters (six feet) across at the surface. The characterization of the Broadwell Basin fissures was conducted on the basis of several approaches. High-resolution S-wave seismic reflection surveying mapped the overall tectonic structure of the basin. The fissures were trenched to as deep as 9 meters (30 feet) to understand their physical characteristics as a function of depth. The timeframe of fissure activity was addressed by means of age dating of carbonized wood from the trench with the C14 technique. A comprehensive program of laboratory testing of disturbed and undisturbed samples was conducted with emphasis placed on understanding the mineralogy of the soils, the distribution of natural moisture content, and the nature of shrinkage of these soils when they are desiccated. The basic conclusion of these studies is that the fissures are not tectonic. They exhibit neither vertical nor horizontal displacement. The fissures currently visible formed hundreds and probably thousands of years ago. Laboratory testing confirms the slow rate of their formation and indicates that the lake sediments are currently at a moisture content where the formation of additional fissures would not be expected to develop under current climatic conditions. © 2010 ASCE.

Ferguson B.K.,University of Georgia | Mickalonis O.,U.S. Army | Ferguson B.K.,Paul C. Rizzo Associates
Urban Water Journal | Year: 2011

Decks or boardwalks are frame structures with plank surfaces for bearing pedestrian traffic. They offer a potential addition to the list of surfacing materials that maintain perviousness of land cover in the midst of urban development. In this study, using the same type of analysis used for grate inlets, it was determined that decks' minimum 'worst case' permeability is higher than common natural rainfall intensities and at least as high as that of competing permeable surfacing materials. Cost analysis demonstrated that the cost of deck construction is comparable to that of competing permeable surfacing materials. Diverse case studies illustrate that there is experience with decks in a variety of urban settings. Therefore it is recommended that decks be on any list of surfaces available for effectively reducing urban impervious cover, while continuing to limit their application to the traffic types for which they are suited. © 2011 Taylor & Francis.

Ferguson B.K.,University of Georgia | Ferguson B.K.,Paul C. Rizzo Associates | Mickalonis O.,U.S. Army
Urban Water Journal | Year: 2013

This paper investigates the possibility that some aggregate gradations could be considered functionally 'pervious', based on comparison of an aggregate's permeability with either natural soil permeabilities or local rainfall intensities. Permeability was estimated by calculation for 27 American standard gradations, based on their porosity, coefficient of uniformity and effective particle size. In addition aggregate's cost relative to other urban surfaces was estimated. The results show that gradations of ASTM D448 No. 9, 89 and larger have high permeabilities relative to both the most permeable soil and the most intense rainfall in the central and eastern United States and so could be considered pervious surfaces in that large region. Denser gradations have lower permeabilities and less claim to be considered pervious. Properly selected aggregate's combination of high permeability and low cost make it an attractive option for reducing impervious cover, under the detailed traffic types for which it is suited. © 2013 Copyright Taylor and Francis Group, LLC.

Charlton J.E.,Paul C. Rizzo Associates | Ginther C.,Paul C. Rizzo Associates | Bruce D.A.,Geosystems L.P.
Environmental and Engineering Geoscience | Year: 2010

The Tennessee Valley Authority (TVA) Bear Creek Dam is a high-hazard potential embankment dam in northwest Alabama that provides water supply, flood control, and recreation benefits. Since its initial filling in 1969, the dam has experienced significant seepage through its karst limestone foundation. After experiencing limited or temporary success at controlling seepage using supplemental grouting programs and downstream seepage collection systems, TVA elected to embark on an extensive rehabilitation effort for the existing dam's deficiencies, as follows: (1) foundation seepage leading to a potential loss of embankment material at the foundation contact and (2) the potential loss of the embankment dam as a result of overtopping during the potential maximum flood (PMF). Paul C. Rizzo Associates, Inc., was hired to design a permanent solution for the dam's deficiencies. Performance of this rehabilitation consists of construction of a downstream roller-compacted concrete reinforcement structure to prevent loss of the dam during PMF overtopping and installation of a composite seepage barrier consisting of a two-line grout curtain with cutoff wall panels at select locations to reduce potentially hazardous foundation seepage. The existing emergency spillway as well as the existing sluiceway tunnel and associated intake structure were preserved as a part of this new construction. This article presents the means and methods employed to effectively treat the karst limestone geology present at the Bear Creek Dam, with emphasis on the evolving nature of the design and construction of the final seepage barrier, whereby continuous, 'real-time' evaluation of the geologic conditions encountered during each phase of the foundation treatment process was used to tailor the scope and design of the next step of the rehabilitation.

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