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Monitoring The Structural Condition Of Fracture-Critical Bridges Using Fiber Optic Technology , Justin Dale Doornink Jan 2006

Monitoring The Structural Condition Of Fracture-Critical Bridges Using Fiber Optic Technology , Justin Dale Doornink

Retrospective Theses and Dissertations

Structural health monitoring (SHM) enables bridge engineers to monitor the structural behavior of entire bridges or individual bridge components. At the request of the Iowa Department of Transportation, a fiber optic SHM system was developed and deployed by the Iowa State University (ISU) Bridge Engineering Center (BEC) to detect gradual or sudden damage in fracture-critical bridges (FCBs). With the equipment that was selected and the software that was developed in this research, the SHM system is deployable to any girder bridge that supports one-way traffic;Significant laboratory and field testing was conducted as part of this research to select hardware ...


Assessing Tradeoffs Between Safety And Operations: An Analytical Framework , David Alexander Veneziano Jan 2006

Assessing Tradeoffs Between Safety And Operations: An Analytical Framework , David Alexander Veneziano

Retrospective Theses and Dissertations

Roadway improvements are often made based on safety or operations. While each factor is important, consideration of one factor may impact another negatively. The tradeoffs between factors are often not well understood. The failure or inability to consider these impacts is of particular concern, as a general improvement in one area (ex. operations), may have adverse results on another;This dissertation presents a methodology to link safety and operations in order to determine the tradeoffs of improvements. A zero-inflated Poisson model was selected to model safety and was specified within a hierarchical Bayesian framework. Bayesian p-values were utilized to establish ...


Early Age Behavior Of Jointed Plain Concrete Pavements Subjected To Environmental Loads , Sunghwan Kim Jan 2006

Early Age Behavior Of Jointed Plain Concrete Pavements Subjected To Environmental Loads , Sunghwan Kim

Retrospective Theses and Dissertations

Studies on deformation characteristics of early-age Jointed Plan Concrete Pavements (JPCP) subjected to pure environmental loading has drawn significant interest as it is believed that the early-age deformation of Portland Cement Concrete (PCC) slab could result in the loss of pavement smoothness and the tensile stresses induced by these deformations could result in early-age cracking. However, the complex interaction of several environmental factors has resulted in difficulties in predicting the JPCP deformation characteristics under environmental loading. Also, the effect of the resulting slab distortion on the initial JPCP smoothness has not been adequately addressed by previous research studies;In this ...


Attached Growth Fungal System For Corn Wet Milling Wastewater Treatment , Nagapadma Jasti Jan 2006

Attached Growth Fungal System For Corn Wet Milling Wastewater Treatment , Nagapadma Jasti

Retrospective Theses and Dissertations

High organic strength food-processing wastewaters are typically treated with conventional aerobic systems such as an activated sludge process that produces substantial quantities of low value bacterial sludge. Treatment and disposal of bacterial sludge place a huge burden on wastewater plants. Industrial wastewaters with high organic content treatment are also often treated with bacterial processes. The research in this dissertation focuses on using fungi to treat food-processing wastewater to produce biomass that is a good source of valuable byproducts (e.g. enzymes, protein, and other bio-chemicals). The recovery of value added products derived from the fungal biomass could generate additional revenue ...


Evaluation Of Long-Term Performance Of Cold In-Place Recycled Asphalt Roads , Dong Chen Jan 2006

Evaluation Of Long-Term Performance Of Cold In-Place Recycled Asphalt Roads , Dong Chen

Retrospective Theses and Dissertations

Asphalt pavements deteriorate over time. Typically three to five years following construction, reflected cracks, one of the primary forms of distress in hot-mix asphalt overlays of flexible pavements, may be observed. When rolled downed, reflected cracks affect ride quality. In addition, reflected cracks allow the penetration of water into the pavement and the base. The water causes the asphalt mix to deteriorate and the base to soften. Consequently the service life of pavements is reduced. Cold In-Place Recycling (CIR) provides an economical rehabilitation method that mitigates crack reflection by pulverizing the asphalt pavement surface, thus destroying the old crack pattern ...


Development Of A New Test Procedure To Evaluate The Moisture Susceptibility Of Hot Mix Asphalt , Jason Paul Bausano Jan 2006

Development Of A New Test Procedure To Evaluate The Moisture Susceptibility Of Hot Mix Asphalt , Jason Paul Bausano

Retrospective Theses and Dissertations

Moisture damage in hot mix asphalt (HMA) pavements has been extensively documented since the late 1970's. The current test method for detecting moisture susceptibility in HMA is American Association of State Highway and Transportation Officials (AASHTO) T283. Inclusion of this test method in Superpave did not consider the change in specimen diameter size from 100mm to 150mm nor corresponding heights, method of compaction, nor is AASHTO T283 a performance test to accompany the mix design procedure;A new test procedure to evaluate the moisture susceptibility of HMA was developed in this dissertation. In addition, two sensitivity studies were undertaken ...


Effect Of Spatial Data Aggregation On Highway Safety Analysis , Justin Cooper Jackson Jan 2006

Effect Of Spatial Data Aggregation On Highway Safety Analysis , Justin Cooper Jackson

Retrospective Theses and Dissertations

In recent highway safety studies, there has been increasing attention to the accuracy and timeliness of crash data, but there have been limited studies on data aggregation. This thesis tests the effects of the underlying preprocessing of crash data for identifying high crash locations. The first portion of this thesis shows a sensitivity analysis of assigning crashes to intersections by spatial proximity and crash data attributes. In addition the sensitivity of using fixed length segmentation was tested along with the influence of using crash rate for identifying high crash locations.;The results indicate minimal effects of using different spatial proximities ...


Key Attributes For Successful Leadership In Construction: Project Managers And Superintendents , Nathaniel Clay Hagberg Jan 2006

Key Attributes For Successful Leadership In Construction: Project Managers And Superintendents , Nathaniel Clay Hagberg

Retrospective Theses and Dissertations

The thesis is a summary of surveys completed at annual construction seminars hosted by the Master Builders of Iowa, Inc. by project managers and superintendents. Seven different surveys are listed regarding the preferences of each group (superintendents and managers). Surveys were conducted on the following subjects: (1) Qualities necessary for the construction industry to remain strong. (2) Attributes a construction company needs to grow and prosper. (3) Attributes an ideal superintendent needs to successfully lead a project. (4) Attributes an ideal project manager needs to successfully lead a project. (5) Attributes for the leader/manager balance required of a project ...


Applicability Of Ultrasound Conditioning Of Waste Activated Sludge To Reduce Foaming Potential In The Anaerobic Digesters , Ferit Isik Jan 2006

Applicability Of Ultrasound Conditioning Of Waste Activated Sludge To Reduce Foaming Potential In The Anaerobic Digesters , Ferit Isik

Retrospective Theses and Dissertations

This study has primarily established ultrasound disintegration as one of the many methods for the pre-treatment of thickened waste activated solids (TWAS) from Denver, CO and Marshalltown, IA WWTPs ranged from 4% to 4.8% of total solid concentration to control foaming in mesophilic anaerobic reactors. A secondary objective of the study was to evaluate the performance of ultrasound-conditioned (sonicated) TWAS for minimizing the retention time and enhancing the destruction of volatile solids. The sonication duration was adjusted to achieve energy inputs equivalent to 1.25 and 1.95 kWs/g of TWAS. Three reactors; control, full-stream reactor that received ...


Verification Of The Whitetopping Thickness Design Procedure For Asphalt Concrete Overlaid Portland Cement Concrete Pavements , Toni Raenette Tabbert Jan 2006

Verification Of The Whitetopping Thickness Design Procedure For Asphalt Concrete Overlaid Portland Cement Concrete Pavements , Toni Raenette Tabbert

Retrospective Theses and Dissertations

Iowa is one of few states with a large number of Portland Cement Concrete (PCC) pavements. Many of these pavements have been rehabilitated by placing multiple layers of Asphalt Concrete (AC) over the existing PCC slabs. However, there was a need for an alternative with a longer life and lower life-cycle cost. With improvements in paving technology such as the slipform paver and the ability to obtain high early age strength, PCC overlays soon became that alternative. Many of the existing overlay design procedures were developed for a single placed layer of pavement and are not applicable to the two ...


Hydrological Modification Of Subsurface Drainage Systems , Kyle Dean Riley Jan 2006

Hydrological Modification Of Subsurface Drainage Systems , Kyle Dean Riley

Retrospective Theses and Dissertations

Controlled Drainage (CD), a subsurface drainage management system, has been researched in many regions. Previous research has reported CD to reduce subsurface drainage and as a result reduce nitrate loading. CD has been reported to have little effect on nitrate concentrations, so exploring alternative treatments to reduce these concentrations would be constructive. This research was intended to measure the effect of CD on surface runoff, crop yield, water table depth, and to document a biofilter's effect on nitrate concentrations. CD increased surface runoff ranging from 53% to 130%, increased corn yield by 14% over two years, and decreased nitrate ...


Biological Nutrient Removal In Bench-Scale Membrane Bioreactor And Full-Scale Sequencing Batch Reactor Under Various Configurations And Conditions , Cagatayhan Bekir Ersu Jan 2006

Biological Nutrient Removal In Bench-Scale Membrane Bioreactor And Full-Scale Sequencing Batch Reactor Under Various Configurations And Conditions , Cagatayhan Bekir Ersu

Retrospective Theses and Dissertations

Biological nutrient removal was studied and modeled for a submerged bench-scale membrane bioreactor (MBR). Of the five configurations studied, the configuration with mixed liquor recirculation to the anaerobic compartment and permeate recirculation to the anoxic compartment gave the best results with 92.3% sCOD, 75.6% TN, 62.4% TP removal, and almost complete nitrification (97.7%) at 25 days SRT and 2 hrs anaerobic, 2 hrs anoxic and 8 hrs oxic HRTs. When recirculation rates were varied within the same configuration, the highest TP removal was 88.1% with 300%/100% (mixed liquor/permeate) recirculation while the highest TN ...


Biological Hydrogen Production By Anaerobic Fermentation , Wen-Hsing Chen Jan 2006

Biological Hydrogen Production By Anaerobic Fermentation , Wen-Hsing Chen

Retrospective Theses and Dissertations

Considering the energy security and the global environment, there is a pressing need to develop non-polluting and renewable energy sources. Alternatively, hydrogen is a clean energy carrier, producing water as its only by-product when it burns. Anaerobic bioconversion of organic wastes to hydrogen gas is an attractive option that not only stabilizes the waste/wastewater, but also generates a benign renewable energy carrier. The purposes of this study were to determine the kinetics of hydrogen production using different characteristics of substrates and to evaluate hydrogen production potential from different operating conditions in continuous operation;The growth kinetics of hydrogen-producing bacteria ...


Development And Evaluation Of Test Procedures To Identify Moisture Damage Prone Hot Mix Asphalt Pavements , Andrea Nicole Kvasnak Jan 2006

Development And Evaluation Of Test Procedures To Identify Moisture Damage Prone Hot Mix Asphalt Pavements , Andrea Nicole Kvasnak

Retrospective Theses and Dissertations

There are numerous factors that can cause a road to deteriorate, such as the traffic type, traffic volume, failure of materials used and climatic conditions. All four of the above listed factors can contribute to permanent deformation, commonly called pavement rutting. Most permanent deformation tests and simulation models have concentrated primarily on material properties and traffic loads. The effects of the environmental conditions are often neglected in these models with only a few accounting for climatic effects. The damaging effect of moisture on pavements, specifically hot mix asphalt (HMA), is a significant environmental distress that should be considered. As pavement ...


Precise Pseudoranges Obtained From Combining Code And Dual Carrier Measurements In Global Positioning System Receivers , Steven D. Deines Jan 2006

Precise Pseudoranges Obtained From Combining Code And Dual Carrier Measurements In Global Positioning System Receivers , Steven D. Deines

Retrospective Theses and Dissertations

The Global Positioning System (GPS), which was declared operational in December 1993, has provided continuous worldwide navigational capabilities in all types of weather. GPS has a minimum of 24 satellites in its constellation with additional fully functional spare satellites, which vary about 30 in total number. This navigational service has provided three-dimensional position within 30 meters and time within 100 ns to the civil community, which typically uses the coarse acquisition (C/A) code. The military GPS user has improved position accuracy within 6 meters using the dual GPS frequencies that carry the precise (P) code. The coarse resolution of ...


Utilization Of Sulfur Dioxide In Organic Acids Recovery And Sulfur Trioxide Conversion With Iron Oxide As Catalyst , Yonghui Shi Jan 2006

Utilization Of Sulfur Dioxide In Organic Acids Recovery And Sulfur Trioxide Conversion With Iron Oxide As Catalyst , Yonghui Shi

Retrospective Theses and Dissertations

Sulfur dioxide (SO2) is a primary air pollutant and its emission is strictly restricted by pertinent regulations. Methodology is to use SO 2 as a raw material to produce valuable chemicals while purifying the flue gas. Two approaches that use SO2 in the flue gas were put forward and examined. In the first approach, SO2 was used to recover acetic acid and lactic acid from the biological process. The second approach converted SO2 to SO3 through oxidation with iron oxide (Fe2O3) as catalyst. The experimental results of acetic and lactic acid recovery showed that both the reaction time and breakthrough ...


Thermal And Fatigue Testing Of Fiber Reinforced Polymer Tie Connectors Used In Concrete Sandwich Walls , Anthony William Post Jan 2006

Thermal And Fatigue Testing Of Fiber Reinforced Polymer Tie Connectors Used In Concrete Sandwich Walls , Anthony William Post

Retrospective Theses and Dissertations

The purpose of this research program was to determine the strength, strain, fatigue, temperature, and other corresponding behavioral characteristics of concrete sandwich wall panels containing the new Delta TieRTM fiber reinforced polymer (FRP) tie connector produced by Dayton/Richmond, a brand of Dayton Superior. The scope of this program included a matrix of three full-scale 40'-0'' wall panels subjected to a 100°F temperature differential, and a matrix of six elemental specimens, three with the ties oriented in the strong direction (parallel tie orientation) and three with the ties oriented in the weak direction (perpendicular tie orientation), subjected to ...


Comparison Of Alternative Laboratory Dowel Bar Testing Procedures , John Francis Harrington Jan 2006

Comparison Of Alternative Laboratory Dowel Bar Testing Procedures , John Francis Harrington

Retrospective Theses and Dissertations

The objective of this study was to evaluate the performance of a modified version of the AASHTO T253 dowel bar test procedure. The modified AASHTO test was developed based upon comparisons to previous ISU projects and was compared to an alternate cantilevered dowel bar test. The dowel bar tests were conducted for the purpose of finding a preferred method of obtaining the Modulus of Dowel Support, k0. The series of tests included 54 modified AASHTO specimens and 18 cantilever specimens. Six different dowel bar types were included in the laboratory tests. The bar shapes were both round and elliptical. The ...


The Effectiveness Of Low-Cost Traffic Calming Applications Appropriate For Main Streets Through Rural Communities , Eric Randall Petersen Jan 2006

The Effectiveness Of Low-Cost Traffic Calming Applications Appropriate For Main Streets Through Rural Communities , Eric Randall Petersen

Retrospective Theses and Dissertations

County and state highways that enter small rural towns commonly become a major roadway through the community. These roadways typically have high speed limits outside of town and transition to a reduced speed limit through the community. Drivers that enter at high speeds and continue speeding throughout create unsafe conditions for residents and other drivers. When speeding becomes a problem, city officials often struggle to find solutions. Most traffic calming studies only focus on minor streets in large, urban areas. Therefore, city officials have little information about the effectiveness of rural traffic calming measures that are appropriate for major highways ...


Nitrogen And Phosphorus Removal In Biological Aerated Filters (Bafs) , Jeonghyub Ha Jan 2006

Nitrogen And Phosphorus Removal In Biological Aerated Filters (Bafs) , Jeonghyub Ha

Retrospective Theses and Dissertations

Three downflow pilot-scale biological aerated filters (BAFs) using different media, gravel, lava rock and plastic rings were operated to study their effectiveness as an add-on system or polishing process for aerated lagoons. Of the three media tested, gravel with a diameter of 5 mm was found to provide more than 96% nitrification at hydraulic retention time (HRT) as low as 0.5 hour with 200% recirculation. Experimental results showed that polishing BAF with gravel can be operated at 1 hour HRT without recirculation with nitrification as high as 83%;At a HRT of 2 hours and a wastewater temperature of ...