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California Polytechnic State University, San Luis Obispo

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Articles 1651 - 1680 of 1728

Full-Text Articles in Civil and Environmental Engineering

Some Traffic Features At Freeway Bottlenecks, Michael J. Cassidy, Robert L. Bertini Feb 1999

Some Traffic Features At Freeway Bottlenecks, Michael J. Cassidy, Robert L. Bertini

Civil and Environmental Engineering

Observations from two freeway bottlenecks in and near Toronto, Canada indicate that the average rate vehicles discharge from a queue can be 10% lower than the flow measured prior to the queue's formation. Absent any influences from downstream, the queue discharge flows exhibited nearly stationary patterns that alternated between higher and lower rates. These alternating flow patterns were especially evident at one of the two sites, although the feature occurred at both sites during periods that immediately followed the onset of upstream queuing; i.e. a queue's formation was always accompanied by a relatively low discharge rate followed later by a …


Production Of Biogenic Mn Oxides By Leptothrix Discophora Ss-1 In A Chemically Defined Growth Medium And Evaluation Of Their Pb Adsorption Characteristics, Yarrow M. Nelson, Leonard W. Lion, William C. Ghiorse, Michael L. Shuler Jan 1999

Production Of Biogenic Mn Oxides By Leptothrix Discophora Ss-1 In A Chemically Defined Growth Medium And Evaluation Of Their Pb Adsorption Characteristics, Yarrow M. Nelson, Leonard W. Lion, William C. Ghiorse, Michael L. Shuler

Civil and Environmental Engineering

Biogenic Mn oxides were produced by the bacterium Leptothrix discophora SS-1 (= ATCC 3182) in a chemically defined mineral salts medium, and the Pb binding and specific surface area of these oxides were characterized. Growth of SS-1 in the defined medium with pyruvate as a carbon and energy source required the addition of vitamin B12. Complete oxidation of Mn(II) within 60 h required the addition of ≥0.1 μM FeSO4. Pb adsorption isotherms were determined for the biogenic Mn oxides (and associated cells with their extracellular polymer) and compared to the Pb adsorption isotherms of cells and …


Model For Trace Metal Exposure In Filter-Feeding Flamingos At Alkaline Rift Valley Lake, Kenya, Yarrow M. Nelson, Ramesh J. Thampy, Gideon K. Motelin, Jackson A. Raini, Cynthia J. Disante, Leonard W. Lion Nov 1998

Model For Trace Metal Exposure In Filter-Feeding Flamingos At Alkaline Rift Valley Lake, Kenya, Yarrow M. Nelson, Ramesh J. Thampy, Gideon K. Motelin, Jackson A. Raini, Cynthia J. Disante, Leonard W. Lion

Civil and Environmental Engineering

Abstract—Toxic trace metals have been implicated as a potential cause of recent flamingo kills at Lake Nakuru, Kenya. Chromium (Cr), copper (Cu), lead (Pb), and zinc (Zn) have accumulated in the lake sediments as a result of unregulated discharges and because this alkaline lake has no natural outlet. Lesser flamingos (Phoeniconaias minor) at Lake Nakuru feed predominantly on the cyanobacterium Spirulina platensis, and because of their filter-feeding mechanism, they are susceptible to exposure to particle-bound metals. Trace metal adsorption isotherms to lake sediments and S. platensis were obtained under simulated lake conditions, and a mathematical model was …


Investigation Of A Cyclic Laterally Loaded Model Pile Group, Robb E.S. Moss, Joseph A. Caliendo, Loren R. Anderson Oct 1998

Investigation Of A Cyclic Laterally Loaded Model Pile Group, Robb E.S. Moss, Joseph A. Caliendo, Loren R. Anderson

Civil and Environmental Engineering

In certain regions of the world, designing deep foundations to withstand seismic loading is a reality. Seismic loading of structures and foundations reaches its most critical state as a cyclic lateral force. The response of soils and foundations to repetitive lateral forces is highly complex, relegating most design methods to be based upon overly conservative rules-of-thumb. The primary objective of this research was to analyze the mechanics of seismic loading on pile groups in clay soils. To achieve this a model testing facility was constructed to house a fully instrumented 1 X 5 model pile group that was subjected to …


Seismic Code Improvements Based On Recorded Motions Of Buildings During Earthquake, Anil K. Chopra, Rakesh K. Goel, Juan Carlos De La Llera Sep 1998

Seismic Code Improvements Based On Recorded Motions Of Buildings During Earthquake, Anil K. Chopra, Rakesh K. Goel, Juan Carlos De La Llera

Civil and Environmental Engineering

Summarized in this paper are the results of two recent investigations utilizing recorded motions of buildings to develop improvements in two aspects of seismic code provisions for buildings: (1) fundamental vibration period formulas, and (2) accidental torsion.


Preliminary Development Of A Certification Protocol For Conventional Fireplaces, Paul L. Reitz, Harold M. Cota Jun 1998

Preliminary Development Of A Certification Protocol For Conventional Fireplaces, Paul L. Reitz, Harold M. Cota

Civil and Environmental Engineering

In order to attain and maintain federal and state air quality standards for particulate matter, some local agencies in California have adopted rules and regulations to control emissions from wood burning devices. Some of these rules restricted the use or installation of new masonry fireplaces. The purpose of this study was to begin development of a test protocol that would provide for consistent measurement of particulate emissions from conventional fireplaces and could be useful for compliance determinations or possible certification of a fireplace design or model. A modified California Air Resources Board Stationary Source Test Method 5 was used to …


Techniques For Modeling Hazardous Air Pollutant Emissions From Landfills, Robert J. Lang, Samuel A. Vigil, Henryk Melcer Jun 1998

Techniques For Modeling Hazardous Air Pollutant Emissions From Landfills, Robert J. Lang, Samuel A. Vigil, Henryk Melcer

Civil and Environmental Engineering

The Environmental Protection Agency’s Landfill Air Estimation Model (LAEEM), combined with either the AP-42 or CAA landfill emission factors, provide a basis to predict air emissions, including hazardous air pollutants (HAPs), from municipal solid waste landfills. This paper presents alternative approaches for estimating HAP emissions from landfills. These approaches include analytical solutions and estimation techniques that account for convection, diffusion, and biodegradation of HAPs. Results from the modeling of a prototypical landfill are used as the basis for discussion with respect to LAEEM results.


Experimental Analysis Of Desiccation Crack Propagation In Clay Liners, Carol J. Miller, Hong Mi, Nazli Yesiller Jun 1998

Experimental Analysis Of Desiccation Crack Propagation In Clay Liners, Carol J. Miller, Hong Mi, Nazli Yesiller

Civil and Environmental Engineering

A laboratory investigation on a scaled model of a landfill liner was conducted to provide data regarding the occurrence and extent of desiccation cracking of prototype liners. The crack intensity factor, CIF, was introduced as a descriptor of the extent of surficial cracking. CIF is defined as the ratio of the surface crack area A, to the total surface area of the clay liner, At. A computer aided image analysis program was used to determine CII’ values from scanned photographs of the desiccation process. The variation of the CII’ was related to duration of drying and measured soil moisture suctions. …


Evaluation Of The Us Epa Recommended Approach To Predicting Air Emissions From Pulp And Paper Industry Landfills, Samuel A. Vigil Apr 1998

Evaluation Of The Us Epa Recommended Approach To Predicting Air Emissions From Pulp And Paper Industry Landfills, Samuel A. Vigil

Civil and Environmental Engineering

There is growing indication that the pulp and paper industry will be required to comply with Clean Air Act (Title V) requirements to estimate emissions of bulk bases and HAPs from landfills. One method of such estimation is through the use of the Landfill Air Emissions Estimation Model (LAEEM), which was developed and calibrated specifically for municipal solid waste (MSW) landfills. The industry is concerned with the applicability of LAEEM because the nature of the materials placed in industry landfills is considered to be so different from those in MSW landfills, that emissions will likely be lower than model predictions. …


Energy Efficient Resource Recovery Project, Daniel Panetta, Douglas Williams, Walter Bremer, Gary Karner, Harap Mallareddy, Margot Mcdonald, Samuel A. Vigil, Bailey Green, Henry Hammer, William J. Oswald, William Roley, Jr. Apr 1998

Energy Efficient Resource Recovery Project, Daniel Panetta, Douglas Williams, Walter Bremer, Gary Karner, Harap Mallareddy, Margot Mcdonald, Samuel A. Vigil, Bailey Green, Henry Hammer, William J. Oswald, William Roley, Jr.

Civil and Environmental Engineering

No abstract provided.


Period Formulas For Concrete Shear Wall Buildings, Rakesh K. Goel, Anil K. Chopra Apr 1998

Period Formulas For Concrete Shear Wall Buildings, Rakesh K. Goel, Anil K. Chopra

Civil and Environmental Engineering

Most seismic codes specify empirical formulas to estimate the fundamental vibration period of buildings. Evaluated first in this paper are the formulas specified in present U.S. codes using the available data on the fundamental period of buildings "measured" from their motions recorded during eight California earthquakes, starting with the 1971 San Fernando earthquake and ending with the 1994 Northridge earthquake. It is shown that current code formulas for estimating the fundamental period of concrete shear wall buildings are grossly inadequate. Subsequently, an improved formula is developed by calibrating a theoretical formula, derived using Dunkerley's method, against the measured period data …


Effects Of Supplemental Viscous Damping On Seismic Response Of Asymmetric-Plan Systems, Rakesh K. Goel Feb 1998

Effects Of Supplemental Viscous Damping On Seismic Response Of Asymmetric-Plan Systems, Rakesh K. Goel

Civil and Environmental Engineering

Coupling between lateral and torsional motions may lead to much larger edge deformations in asymmetric‐plan systems compared to systems with a symmetric plan. Supplemental viscous damping has been found to be effective in reducing deformations in the symmetric‐plan system. This investigation examined how supplemental damping affects the edge deformations in asymmetric‐plan systems. First, the parameters that characterize supplemental viscous damping and its plan‐wise distribution were identified, and then the effects of these parameters on edge deformations were investigated. It was found that supplemental damping reduces edge deformations and that reductions by a factor of up three are feasible with proper …


Seismic Code Analysis Of Multi-Storey Asymmetric Buildings, Anthony P. Harasimowicz, Rakesh K. Goel Feb 1998

Seismic Code Analysis Of Multi-Storey Asymmetric Buildings, Anthony P. Harasimowicz, Rakesh K. Goel

Civil and Environmental Engineering

Static torsional provisions in most seismic codes require that the lateral force at each floor level be applied at some distance from the reference centre at that floor. However, codes do not specify how to determine the locations of these centres. As a result, several different definitions of the reference centres are being used to implement the code analysis. This investigation examined how the results using various reference centres differ and which of these centres would lead to results that are in agreement with those of dynamic analysis. For this purpose three different buildings ranging form torsionally stiff to torsionally …


Stability And Performance Of Feedback Control Systems With Time Delays, M. S. Ali, Z. K. Hou, Mohammad N. Noori Jan 1998

Stability And Performance Of Feedback Control Systems With Time Delays, M. S. Ali, Z. K. Hou, Mohammad N. Noori

Office of the Dean (CENG) Scholarship

This paper investigates the time delay effects on the stability and performance of active feedback control systems for engineering structures. A computer algorithm is developed for stability analysis of a SDOF system with unequal delay time pair in the velocity and displacement feedback loops. It is found that there may exist multiple stable regions in the plane of the time delay pair, which contain time delays greater than the maximum allowable values obtained by previous studies. The size, shape and location of these stable and unstable regions depend on the system parameters and the feedback control gains. For systems with …


Seismic Response Of Asymmetric Systems: Energy-Based Approach, Rakesh K. Goel Nov 1997

Seismic Response Of Asymmetric Systems: Energy-Based Approach, Rakesh K. Goel

Civil and Environmental Engineering

An energy-based approach has been used to investigate the seismic behavior of code-designed asymmetric-plan systems. The systems considered in this investigation had large eccentricities in both directions, were designed for bidirectional earthquake loading, and their responses were computed with both components of ground motion acting simultaneously. The presented results demonstrate that the total input energy is about the same whether the system plan is symmetric or asymmetric. Furthermore, flexible-side elements in asymmetric- plan systems may be more vulnerable to earthquakes than the same elements in symmetric-plan systems if they are not designed to accommodate the higher hysteretic-energy demands. This observation …


Earthquake Characteristics Of Bridges With Integral Abutments, Rakesh K. Goel Nov 1997

Earthquake Characteristics Of Bridges With Integral Abutments, Rakesh K. Goel

Civil and Environmental Engineering

Earthquake analysis of bridges requires that the period and damping ratio be determined for each significant mode of vibration. Data on these vibration properties, identified from motions of bridges recorded during actual earthquake events, provide the most direct means of verifying and improving the current guidelines. Thus, the aim of this investigation was to measure the vibration properties of a two-span concrete bridge from its motions recorded during actual earthquake events. These data were then used to investigate how abutment participation affected the vibration properties of bridges with integral abutments. It is shown that the vibration period elongated and the …


Period Formulas For Moment-Resisting Frame Buildings, Rakesh K. Goel, Anil K. Chopra Nov 1997

Period Formulas For Moment-Resisting Frame Buildings, Rakesh K. Goel, Anil K. Chopra

Civil and Environmental Engineering

Most seismic codes specify empirical formulas to estimate the fundamental vibration period of buildings. Evaluated first in this paper are the formulas specified in present U.S. codes using the available data on the fundamental period of buildings "measured" from their motions recorded during eight California earthquakes, starting with the 1971 San Fernando earthquake and ending with the 1994 Northridge earthquake. It is shown that, although the code formulas provide periods that are generally shorter than measured periods, these formulas can be improved to provide better correlation with the measured data. Subsequently, improved formulas for estimating the fundamental periods of reinforced …


Field Evaluation Of Ultrasonic Method For Assessing Well Seals, Nazli Yesiller, Craig H. Benson, Tuncer B. Edil Aug 1997

Field Evaluation Of Ultrasonic Method For Assessing Well Seals, Nazli Yesiller, Craig H. Benson, Tuncer B. Edil

Civil and Environmental Engineering

Field tests were conducted in three boreholes using an ultrasonic testing method to evaluate its ability to assess contact between the seal and riser (casing). The ultrasonic method is used inside the riser without disturbing the riser, seal, or formation soil. The risers were 50-mm-diameter (2-inch) Schedule 40 steel pipes that are used for ground water monitoring wells. Different types of seals were placed around the risers and defects were purposely introduced in the seals to test the ultrasonic method. The ultrasonic response changed as the neat-cement seals cured or hydration of the bentonite seals changed. When adequate moisture was …


Studying Initiation And Growth Of Shear Cracks In Reinforced Concrete Beams Using Full-Field Digital Imaging, Daniel C. Jansen, Sokhwan Choi, Surendra P. Shah Jul 1997

Studying Initiation And Growth Of Shear Cracks In Reinforced Concrete Beams Using Full-Field Digital Imaging, Daniel C. Jansen, Sokhwan Choi, Surendra P. Shah

Civil and Environmental Engineering

The mechanisms which lead to shear failure of longitudinally reinforced concrete beams are complex and often misunderstood. In this paper, a combination of a special closed loop test technique and machine vision are applied to tests on two reinforced concrete beams failing in shear: one made of normal strength concrete and the second of high strength concrete. To control the progression of the shear crack, a closed-loop test technique was devised and employed such that the crack propagation was stable even during the post peak. To locate the crack and to measure the crack displacements, machine vision, a nondestructive measuring …


Environmental Engineering Design, Harold M. Cota, Samuel A. Vigil Jun 1997

Environmental Engineering Design, Harold M. Cota, Samuel A. Vigil

Civil and Environmental Engineering

This paper outlines the capstone environmental engineering design course that has been used effectively at California Polytechnic State University. Senior level students work in teams on a multi-media industrial problem. The experience involves literature review, problem formulation, proposal writing, time management, technical and economic analysis and an oral and written presentation of the results. Feedback from alumni and employers has been positive.


Energy Based Approach To Earthquake Response Of Asymmetric Systems, Rakesh K. Goel Apr 1997

Energy Based Approach To Earthquake Response Of Asymmetric Systems, Rakesh K. Goel

Civil and Environmental Engineering

No abstract provided.


Evaluation Of Code Period Formula For Concrete Mrf Buildings, Rakesh K. Goel, Anil K. Chopra Apr 1997

Evaluation Of Code Period Formula For Concrete Mrf Buildings, Rakesh K. Goel, Anil K. Chopra

Civil and Environmental Engineering

The empirical formula specified in US building codes for fundamental vibration period of concrete moment resisting frame buildings is evaluated using periods of buildings measured from their strong motion records. The presented results show that the current code formula may lead to fundamental periods that are much shorter than the measured periods. In order to obtain better correlation between measured and computed periods, regression analysis technique has been used. The results indicate that the value of C, in the current code formula should be increased from its present value of 0.030 to 0.035.


Permeability Study Of Cracked Concrete, Kejin Wang, Daniel C. Jansen, Surendra P. Shah, Alan F. Karr Mar 1997

Permeability Study Of Cracked Concrete, Kejin Wang, Daniel C. Jansen, Surendra P. Shah, Alan F. Karr

Civil and Environmental Engineering

Cracks in concrete generally interconnect flow paths and increase concrete permeability. The increase in concrete permeability due to the progression of cracks allows more water or aggressive chemical ions to penetrate into the concrete, facilitating deterioration. The present work studies the relationship between crack characteristics and concrete permeability. In this study, feedback controlled splitting tests are introduced to generate crack width-controlled concrete specimens. Sequential crack patterns with different crack widths are viewed under a microscope. The permeability of cracked concrete is evaluated by water permeability tests. The preliminary results indicate that crack openings generally accelerate water flow rate in concrete. …


Ultrasonic Method For Evaluation Of Annular Seals For Wells And Instrument Holes, Nazli Yesiller, Tuncer B. Edil, Craig H. Benson Mar 1997

Ultrasonic Method For Evaluation Of Annular Seals For Wells And Instrument Holes, Nazli Yesiller, Tuncer B. Edil, Craig H. Benson

Civil and Environmental Engineering

An ultrasonic testing method employing the pulse-echo inspection technique was developed to assess the integrity of annular seals surrounding casings (i.e., instrument tubes or well casings). This nondestructive testing method permits testing a seal from inside a casing without disturbing the casing, seal, or formation. Seals constructed with cement-based and bentonite-based sealants surrounding various types and sizes of casings can be evaluated using the method. An evaluation is conducted by sending and receiving ultrasonic waves using a single piezoelectric transducer and commercially available hardware (a pulser receiver and a waveform analyzer). A probe was designed and constructed for downhole testing. …


Evaluation Of Bridge Abutment Capacity And Stiffness During Earthquakes, Rakesh K. Goel, Anil K. Chopra Feb 1997

Evaluation Of Bridge Abutment Capacity And Stiffness During Earthquakes, Rakesh K. Goel, Anil K. Chopra

Civil and Environmental Engineering

The “actual” capacity and stiffness values of the abutment‐soil systems at the US 101/Painter Street Overpass, determined from its earthquake motions, are used to investigate how abutment stiffness varies during earthquakes and to evaluate current modeling procedures. It is found that the “actual” abutment stiffness may be significantly different during different phases of the shaking and decreases significantly as the abutment deformation increases. The CALTRANS modeling procedure leads to a good estimate of the transverse abutment stiffness and capacity. However, this procedure may overestimate the normal abutment stiffness and capacity by a factor of over two, indicating that the assumed …


Effect Of Length On Compressive Strain Softening Of Concrete, Daniel C. Jansen, Surendra P. Shah Jan 1997

Effect Of Length On Compressive Strain Softening Of Concrete, Daniel C. Jansen, Surendra P. Shah

Civil and Environmental Engineering

The concept of localization during the postpeak of compressive strain softening is presented. To explore localization in compression, a feedback-control method using a linear combination of displacement and force that partially subtracts the elastic response of the specimen to give a stable feedback signal is used. Results are presented from two test series (45 and 90 MPa) that use this method to test cylinders with length-to-diameter ratios ranging from 2.0 to 5.5. It is shown that compression failure is in fact a localized phenomenon. The compressive fracture energy is divided into energy dissipated in the prepeak and the postpeak portions …


Assessment Of Cased-Borehole Seals Using An Ultrasonic Method, Nazli Yesiller, Craig H. Benson, Tuncer B. Edil, James Klima Jan 1997

Assessment Of Cased-Borehole Seals Using An Ultrasonic Method, Nazli Yesiller, Craig H. Benson, Tuncer B. Edil, James Klima

Civil and Environmental Engineering

Tests were conducted in Wisconsin from 1994 through 1996 in several boreholes using an ultrasonic method that was developed at the University of Wisconsin-Madison to assess the integrity of annular seals. Initially, three model boreholes simulating monitoring wells were installed to evaluate the effectiveness of the ultrasonic method. Different types of seals were placed around the casings and defects were purposely introduced in the seals to test the ultrasonic method. The ultrasonic method was effective for detecting the presence of different types of seals and defects and also the changes in the condition of seals with time. Then tests were …


Capacity And Stiffness Of Bridge Abutments During Earthquakes, Rakesh K. Goel Dec 1996

Capacity And Stiffness Of Bridge Abutments During Earthquakes, Rakesh K. Goel

Civil and Environmental Engineering

No abstract provided.


Source Reduction And Recycling Programs At A Joint Venture Automobile Assembly Plant, Stuart E. Rupp, Samuel A. Vigil Jun 1996

Source Reduction And Recycling Programs At A Joint Venture Automobile Assembly Plant, Stuart E. Rupp, Samuel A. Vigil

Civil and Environmental Engineering

New United Motor Manufacturing, Inc. (NUMMI) is a vehicle assembly plant in Fremont, California. NUMMI began operations in 1984 as ajoint venture of General Motors Corporation and Toyota Motor Corporation. In 1995, NUMMI produced 94,280 Geo Prizms, 135,112 Toyota Corollas, and 123,257 Toyota Tacoma trucks. NUMMI conducts its manufacturing operations using the Toyota Production System (TPS). A key element of TPS is the elimination of waste. This includes wasted energy, space, labor, and production materials. Waste reduction, i.e., source reduction, is part of NUMMI's corporate culture and every team member is encouraged to continuously seek out new waste reduction opportunities. …


Determination Of Iron Colloid Size Distribution In The Presence Of Suspended Cells: Application To Iron Deposition Onto A Biofilm Surface, Waihung Lo, Yarrow M. Nelson, Leonard W. Lion, Michael L. Shuler, William C. Ghiorse Apr 1996

Determination Of Iron Colloid Size Distribution In The Presence Of Suspended Cells: Application To Iron Deposition Onto A Biofilm Surface, Waihung Lo, Yarrow M. Nelson, Leonard W. Lion, Michael L. Shuler, William C. Ghiorse

Civil and Environmental Engineering

Transport and deposition of colloidal Fe, Mn and Al oxides play key roles in the cycling of toxic transition metals in aquatic environments because these colloids strongly bind transition metals. Further, attachment of biological cells and biofilm growth on surfaces can indirectly affect toxic metal distribution by influencing the deposition of colloidal oxides to surfaces. To elucidate the mechanisms governing these processes, deposition of colloidal oxides onto surfaces must be evaluated in the presence of suspended and adherent bacterial cells. Both particle size and concentration are expected to influence deposition. An experimental protocol was developed to determine the size distribution …