Moving Bed Biofilm Reactors: Evaluation Of Geometry, Attachment Surface Material And Biofilm Populations On The Uptake Of Ammonia And Synthetic Organic Contaminants In Wastewater., 2017 University of New Mexico
Moving Bed Biofilm Reactors: Evaluation Of Geometry, Attachment Surface Material And Biofilm Populations On The Uptake Of Ammonia And Synthetic Organic Contaminants In Wastewater., Patrick D. Mclee
Civil Engineering ETDs
Plastic biofilm carriers are used in biological wastewater treatment to encourage the attachment and retention of microorganisms that metabolize pollutants. The following research was conducted to better understand how different characteristics of the biofilm carrier affect the treatment performance of the attached biofilms in moving bed bioreactors. Lab scale reactors were used in this study to grow nitrifying biofilms in reactors with contrasting and controlled conditions. The effect of surface geometry on nitrification performance was evaluated by testing commercially available moving bed bioreactor media that contrast in physical design, and by varying operational parameters. Additionally, mature biofilm from a similar ...
A Comprehensive Data Driven Evaluation Of Wide Area Probe Data: Opportunities And Challenges., 2017 Iowa State University
A Comprehensive Data Driven Evaluation Of Wide Area Probe Data: Opportunities And Challenges., Yaw Okyere Adu-Gyamfi, Anuj Sharma, Skylar Knickerbocker, Neal R. Hawkins, Michael Jackson
There is a growing desire, among transportation organizations and state DOTs, to consider augmenting traditional traffic data collection with probe - based services for expanded coverage under constrained budgets. The nature of traffic data collection with probes is however dramatically different from traditional traffic data collection techniques. This affects how the new technology is applied and used to solve current traffic problems such as traffic incident management and roadway performance assessment. The current paper summarizes the experiences and lessons learned while using probe data for traffic operations and safety management and makes recommendations on opportunities to maximize the use of probe ...
Unbound Material Characterisation With Nottingham Asphalt Tester, 2017 Iowa State University
Unbound Material Characterisation With Nottingham Asphalt Tester, Sunghwan Kim, Kasthurirangan Gopalakrishnan, Halil Ceylan
The resilient modulus (MR) of unbound materials is a required input in most of the mechanistic-based pavement analysis and design process and has a significant effect on the projected pavement performance in the mechanistic– empirical pavement design guide programme or AASHTOWare DARwin. The Iowa Department of Transportation (DOT) recently acquired a servo-hydraulic dynamic loading materials test system known as the Nottingham asphalt tester (NAT). The Iowa DOT NAT is a hybrid servo-hydraulic machine designed for testing not only hot-mix asphalt performance properties but also unbound materials’ MR (although this has not been verified so far). The primary objectives of this ...
Stiffness Characterisation Of Full-Scale Airfield Test Pavements Using Computational Intelligence Techniques, 2017 Iowa State University
Stiffness Characterisation Of Full-Scale Airfield Test Pavements Using Computational Intelligence Techniques, Kasthurirangan Gopalakrishnan, Halil Ceylan
The falling weight deflectometer (FWD) is a non-destructive test equipment used to assess the structural condition of highway and airfield pavement systems and to determine the moduli of pavement layers. The backcalculated moduli are not only good pavement layer condition indicators but are also necessary inputs for conducting mechanistic based pavement structural analysis. In this study, artificial neural networks (ANNs)-based backcalculation models were employed to rapidly and accurately predict flexible airport pavement layer moduli from realistic FWD deflection basins acquired at the U.S. Federal Aviation Administration's National Airport Pavement Test Facility (NAPTF). The uniformity characteristics of NAPTF ...
Using X-Ray Computed Tomography To Study Paving Materials, 2017 Iowa State University
Using X-Ray Computed Tomography To Study Paving Materials, Kasthurirangan Gopalakrishnan, Halil Ceylan, F. Inanc
X-ray computed tomography, a non-destructive threedimensional imaging tool, has been very helpful in medical diagnosis since the first commercial tomographs were constructed in 1973. In recent years it has gained increasing applications in civil engineering materials research. Several investigators have illustrated the use of computed tomography scans for the non-destructive evaluation of soils and have shown promising applications in characterisation, modelling and computational simulation to optimise asphalt concrete mix design, predict performance and conduct investigative forensic studies. This paper provides a detailed review of X-ray computed tomography applications in characterising asphalt concrete and also describes preliminary studies conducted at the ...
Use Of Pavement Management Information System For Verification Of Mechanistic-Empirical Pavement Design Guide Performance Predictions, Sunghwan Kim, Halil Ceylan, Kasthurirangan Gopalakrishnan, Omar G. Smadi
The performance models used in the Mechanistic-Empirical Pavement Design Guide (MEPDG) are nationally calibrated with design inputs and performance data obtained primarily from the national Long-Term Pavement Performance database. It is necessary to verify and calibrate MEPDG performance models for local highway agencies' implementation by taking into account local materials, traffic information, and environmental conditions. This paper discusses the existing pavement management information system (PMIS) with respect to the MEPDG and the accuracy of the nationally calibrated MEPDG prediction models for Iowa highway conditions. All the available PMIS data for Interstate and primary road systems in Iowa were retrieved from ...
Sensitivity Quantification Of Jointed Plain Concrete Pavement Mechanistic-Empirical Performance Predictions, 2017 Iowa State University
Sensitivity Quantification Of Jointed Plain Concrete Pavement Mechanistic-Empirical Performance Predictions, Halil Ceylan, Sunghwan Kim, Kasthurirangan Gopalakrishnan, Charles W. Schwartz, Rui Li
This paper focuses on quantitative and qualitative sensitivity analyses of various jointed plain concrete pavement (JPCP) mechanistic-empirical design scenarios. Two base cases of JPCP types were utilized: (1) new construction on granular base (new JPCP case), and (2) both new construction/reconstruction on stabilized foundations or rehabilitation on underlying asphalt/concrete layers (JPCP over stiff foundation case). Each base case was designed for three traffic levels in five climate zones to evaluate the sensitivity of predicted distresses using the American Association of State Highway and Transportation Officials (AASHTOs) mechanistic-empirical pavement design guide (MEPDG) procedure. Sensitivity is characterized by a design ...
Neural Networks Modeling Of Stress Growth In Asphalt Overlays Due To Load And Thermal Effects During Reflection Cracking, Halil Ceylan, Kasthurirangan Gopalakrishnan, Robert L. Lytton
Although several techniques have been introduced to reduce reflective cracking, one of the primary forms of distress in hot-mix asphalt (HMA) overlays of flexible and rigid pavements, the underlying mechanism and causes of reflective cracking are not yet well understood. Fracture mechanics is used to understand the stable and progressive crack growth that often occurs in engineering components under varying applied stress. The stress intensity factor (SIF) is its basis and describes the stress state at the crack tip. This can be used with the appropriate material properties to calculate the rate at which the crack will propagate in a ...
Sensitivity Analysis Of Rigid Pavement Systems Using The Mechanistic-Empirical Design Guide Software, 2017 Iowa State University
Sensitivity Analysis Of Rigid Pavement Systems Using The Mechanistic-Empirical Design Guide Software, Alper Guclu, Halil Ceylan, Kasthurirangan Gopalakrishnan, Sunghwan Kim
Initiatives are underway to implement the new mechanistic-empirical pavement design guide (MEPDG) in Iowa. This paper focuses on the sensitivity study of jointed plain concrete pavements (JPCP) and continuously reinforced concrete pavements (CRCP) in Iowa using the MEPDG software. In this comprehensive study, the effect of MEPDG input parameters on the rigid pavement performance is evaluated using the different versions of the MEPDG software (0.7, 0.9, and 1.0) available to date. Representative JPCP and CRCP sections in Iowa were selected for analysis. Based on the sensitivity plots obtained from the MEPDG runs, the design input parameters were ...
Smoothness Variations In Early-Age Jointed Plain Concrete Pavements, 2017 Iowa State University
Smoothness Variations In Early-Age Jointed Plain Concrete Pavements, Sunghwan Kim, Halil Ceylan, Kasthurirangan Gopalakrishnan
This paper discusses the variations in the early-age pavement smoothness at different measurement times and locations in three jointed plain concrete pavements (JPCPs) representing different ranges of construction times. Surface profile measurements were made during the early morning and late afternoon hours at different locations of the instrumented JPCPs during the first 7 d after construction. Variations in pavement temperature during this critical period were monitored using temperature sensors installed within the test sections. The results show that measurable changes of early-age jointed plain concrete pavement (JPCP) smoothness do occur at different measurement times and locations. Within the scope of ...
Renewable Biomass-Derived Lignin In Transportation Infrastructure Strengthening Applications, 2017 Iowa State University
Renewable Biomass-Derived Lignin In Transportation Infrastructure Strengthening Applications, Kasthurirangan Gopalakrishnan, Halil Ceylan, Sunghwan Kim
Lignin is considered as nature's most abundant aromatic polymer co-generated during papermaking and biomass fractionation. There are different types of lignins depending on the source (hardwood, softwood, annual crops, etc.) and recovery process. Recently, an emerging class of lignin products, namely sulphur-free lignins, from biomass conversion processes, solvent pulping and soda pulping, have generated interesting new applications owing to their versatility. As the renewable energy industry is expanding into developing the next generation of biofuels based on cellulosic biomass (e.g. corn stover, forest products waste, switch grass), abundant supply of sulphur-free lignin will become available as co-products for ...
Performance Evaluation Of Roadway Subdrain Outlets In Iowa, 2017 Iowa State University
Performance Evaluation Of Roadway Subdrain Outlets In Iowa, Sunghwan Kim, Kasthurirangan Gopalakrishnan, Halil Ceylan, Robert F. Steffes
The bearing capacity and service life of a pavement are adversely affected by the presence of undrained water in the pavement layers. In cold winter climates, such as in Iowa, this problem is magnified further by the risk of frost damage when water is present. Therefore, wellperforming subsurface drainage systems form an important aspect of pavement design by the Iowa Department of Transportation (DOT). However, there was a need to determine the impacts of not maintaining the subdrain outlets on pavement performance in Iowa in light of the recent Iowa DOT field maintenance staff reductions and budget cuts and the ...
Soil Stabilization With Bioenergy Coproduct, 2017 Iowa State University
Soil Stabilization With Bioenergy Coproduct, Halil Ceylan, Kasthurirangan Gopalakrishnan, Sunghwan Kim
The production and use of biofuel have increased under the context of sustainable development. Biofuel production from plant biomass not only produces biofuel or ethanol but also coproduces products containing lignin, modified lignin, and lignin derivatives. The use of lignin-containing biofuel coproduct in pavement soil stabilization was explored as a new application area. The primary experimental test plan encompassed the comparison of coproduct-treated soils, untreated soils, and traditional stabilizer-treated soils in terms of their strengths. The focus of the secondary experimental test plan was to investigate the effect of additive combinations on strength improvement. The laboratory test matrix in each ...
Novel Nanocomposite Technologies For Dynamic Monitoring Of Structures: A Comparison Between Cement-Based Embeddable And Soft Elastomeric Surface Sensors, Filippo Ubertini, Simon Laflamme, Halil Ceylan, Annibale L. Materazzi, Gianluca Cerni, Hussam Saleem, Antonella D'Alessandro, Alessandro Corradini
The authors have recently developed two novel solutions for strain sensing using nanocomposite materials. While they both aim at providing cost-effective solutions for the monitoring of local information on large-scale structures, the technologies are different in their applications and physical principles. One sensor is made of a cementitious material, which could make it suitable for embedding within the core of concrete structures prior to casting, and is a resistor, consisting of a carbon nanotube cement-based transducer. The other sensor can be used to create an external sensing skin and is a capacitor, consisting of a flexible conducting elastomer fabricated from ...
Rehabilitation Of Concrete Pavements Utilizing Rubblization: A Mechanistic Based Approach To Hma Overlay Thickness Design, Halil Ceylan, Kasthurirangan Gopalakrishnan, Brian Coree, Tejeswi Kota, Reshma Mathews
In Iowa, there are many portland cement concrete (PCC) type highway pavements. These pavements deteriorate over time due to materials, traffic and environmental related distresses and they are commonly rehabilitated by providing a hot-mix asphalt (HMA) overlay. To mitigate reflection cracking, a frequently observed distress on HMA overlaid PCC pavements, various fractured slab techniques are used, of which rubblization is considered to be the most utilized and effective technique. This paper describes the development of a mechanistic-empirical (M-E) thickness design system for HMA overlaid rubblized PCC pavements. In this computerized design procedure, HMA fatigue and subgrade rutting failure are considered ...
Sensitivity Analysis Frameworks For Mechanistic-Empirical Pavement Design Of Continuously Reinforced Concrete Pavements, Halil Ceylan, Sunghwan Kim, Kasthurirangan Gopalakrishnan, Charles W. Schwartz, Rui Li
The new AASHTO Mechanistic-Empirical Pavement Design Guide (MEPDG) performance predictions for the anticipated climatic and traffic conditions depend on the values of the numerous input parameters that characterize the pavement materials, layers, design features, and condition. This paper proposes comprehensive local sensitivity analyses (LSA) and global sensitivity analyses (GSA) methodologies to evaluate continuously reinforced concrete pavement (CRCP) performance predictions with MEPDG inputs under various climatic and traffic conditions. A design limit normalized sensitivity index (NSI) was implemented in both LSA and GSA to capture quantitative as well as qualitative sensitivity information. The GSA varied all inputs simultaneously across the entire ...
Integration Of A Prototype Wireless Communication System With Micro-Electromechanical Temperature And Humidity Sensor For Concrete Pavement Health Monitoring, Shuo Yang, Keyan Shen, Halil Ceylan, Sunghwan Kim, Daji Qiao, Kasthurirangan Gopalakrishnan
In recent years, structural health monitoring and management (SHMM) has become a popular approach and is considered essential for achieving well-performing, long-lasting, sustainable transportation infrastructure systems. Key requirements in ideal SHMM of road infrastructure include long-term, continuous, and real-time monitoring of pavement response and performance under various pavement geometry-materials-loading configurations and environmental conditions. With advancements in wireless technologies, integration of wireless communications into sensing device is considered an alternate and superior solution to existing time- and labor-intensive wired sensing systems in meeting the requirements of an ideal SHMM. This study explored the development and integration of a wireless communications sub-system ...
Neural Network-Based Approach For Analysis Of Rigid Pavement Systems Using Deflection Data, 2017 Iowa State University
Neural Network-Based Approach For Analysis Of Rigid Pavement Systems Using Deflection Data, M. Birkan Bayrak, Halil Ceylan
This paper focuses on the development of backcalculation models based on artificial neural networks (ANNs) for predicting the layer moduli of the jointed plain concrete pavements, that is, the elastic modulus of the portland cement concrete (PCC) layer and the coefficient of subgrade reaction for the pavement foundation. The ANN-based models were trained to predict the layer moduli by using the falling-weight deflectometer (FWD) deflection basin data and the thickness of the concrete pavement structure. The ISLAB2000 finite element program, extensively tested and validated for more than 20 years, has been employed as an advanced structural model for solving the ...
Highway Infrastructure Health Monitoring Using Micro-Electromechanical Sensors And Systems (Mems), 2017 Iowa State University
Highway Infrastructure Health Monitoring Using Micro-Electromechanical Sensors And Systems (Mems), Halil Ceylan, Kasthurirangan Gopalakrishnan, Sunghwan Kim, Peter C. Taylor, Maxim Mikhaylovich Prokudin, Ashley F. Buss
The development of novel "smart" structures by embedding sensing capabilities directly into the construction material during the manufacturing and deployment process has attracted significant attention in autonomous structural health monitoring (SHM). Micro-electromechanical systems (MEMS) provide vast improvements over existing sensing methods in the context of SHM of highway infrastructure systems, including improved system reliability, improved longevity and enhanced system performance, improved safety against natural hazards and vibrations, and a reduction in life cycle cost in both operating and maintaining the infrastructure. Advancements in MEMS technology and wireless sensor networks provide opportunities for long-Term, continuous, real-Time structural health monitoring of pavements ...
Noise-Tolerant Inverse Analysis Models For Nondestructive Evaluation Of Transportation Infrastructure Systems Using Neural Networks, Halil Ceylan, Kasthurirangan Gopalakrishnan, Mustafa Birkan Bayrak, Alper Guclu
The need to rapidly and cost-effectively evaluate the present condition of pavement infrastructure is a critical issue concerning the deterioration of ageing transportation infrastructure all around the world. Nondestructive testing (NDT) and evaluation methods are well-suited for characterising materials and determining structural integrity of pavement systems. The falling weight deflectometer (FWD) is a NDT equipment used to assess the structural condition of highway and airfield pavement systems and to determine the moduli of pavement layers. This involves static or dynamic inverse analysis (referred to as backcalculation) of FWD deflection profiles in the pavement surface under a simulated truck load. The ...