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- Title
- OPTIMAL SIGNAL TIMING DESIGN FOR URBAN STREET NETWORKS UNDER USER EQUILIBRIUM BASED TRAFFIC CONDITIONS
- Creator
- Liu, Yi
- Date
- 2015, 2015-05
- Description
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In the ever-growing travel demand, traffic congestion on freeways and expressways recurs more frequently at a higher number of locations and...
Show moreIn the ever-growing travel demand, traffic congestion on freeways and expressways recurs more frequently at a higher number of locations and for longer durations with added severity. This becomes especially true in large metropolitan areas. Particular to the urban areas, excessive crowdedness caused by inefficient traffic control also results in urban street networks operating in near or over-saturated conditions, leading to unpleasant travel experience due to long delays at intersections. As a consequence, the recurrent traffic congestion on roadway segments and vehicle delays at intersections inevitably compromise energy efficiency, traffic mobility improvement, safety enhancement, and environmental impacts mitigation. All too often, neither restraining travel demand nor expanding system capacity is desirable and practical. Conversely, effectively utilizing the capacity of the existing transportation system has been increasingly thought of as the solution to congestion relief. With respect to the urban street networks, developing effective means for urban intersection signal optimization becomes essential to reduce intersection delays. Conventional signal timing optimization methods use historical traffic data and assume that traffic flows will remains unchanged after the implementation of new signal timing plans. Traffic flows are assumed to be constant, but in fact, when signal timing plans change, travel times for some travel routes will alter, which requires drivers in the network to adjust their choice of travel routes to arrive at the destinations, and result in redistribution of traffic in the network. Therefore, the effects of interactions between signal timing plans and traffic flows need to be explicitly taken into consideration. This study introduces a new methodology that jointly considers signal timing optimization and traffic assignment in an overall analytical framework that contains model formulations under assumptions consistent with real world situations. Such a framework is well suited for applications in real world cases. Specifically, the overall optimization framework is formulated as a bilevel optimization problem. In the proposed basic model, at the upper level, a traffic signal timing optimization problem for urban network is introduced to minimize system total travel time by optimizing signal green splits. At the lower level, a static user equilibrium problem is formulated for networkwide traffic assignment. In the vehicle delay estimation, the time-dependent stochastic delay model in the 2010 Highway Capacity Manual (HCM 2010) is employed and formulated as Variational Inequality constraints, what allow the state-of-the-art MPEC solver, GAMS/NLPEC, to solve the problem for a local optimal effectively and efficiently. The bi-level optimization model is first tested using a small network (the test network) and a computational experiment using a subarea network in the Chicago central district is conducted to assess the practicality of the model formulation in real world applications. In order to import more reality to the basic model and also consider the potential system benefit that comes from different signal phasing design, an enhanced model is developed based on the basic model by employing integer and binary variables. Formulating the problem with binary variables allows for the selection of proper phasing design. Heuristic solution methods are proposed and tested using the test network.
Ph.D. in Civil Engineering, May 2015
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- Title
- DEGRADATION RATE MODEL TO ESTIMATE SOIL CARBON SEQUESTRATION
- Creator
- Zhai, Wenjuan
- Date
- 2016, 2016-05
- Description
-
Concern over climate change as a consequence of carbon dioxide (CO2) emissions from human activities has resulted in efforts to better...
Show moreConcern over climate change as a consequence of carbon dioxide (CO2) emissions from human activities has resulted in efforts to better understand potential mitigation measures such as carbon sequestration in soils. Processes shaping natural carbon sequestration may be used to remove excess CO2 from combustion and other anthropogenic sources of carbon, and, alleviate concerns over climate change. Land application of biosolids is a process that increases the amount of soil carbon sequestration and may produce carbon credits in accordance with the definition of UN Climate Change Convention. A dynamic degradation rate model (DRM) has been developed based on a mass balance and first order kinetics to describe the soil organic carbon (SOC) decomposition process, which provides insights on carbon sequestration due to microbial biomass, SOC, CO2 emission rates, residence time of sequestered carbon, and biomass to biosolids ratios. A curve fitting approach was used to produce a best fit average degradation rate for biosolids degradation and microbial biomass yield. This study employed a 34-year biosolids application database from the literature to determine the amount of carbon sequestered in 41 strip-mined Illinois fields. The DRM application identifies two SOC phases in soil. Soil organic carbon gain in phase one (first 10 yrs) is primarily due to biosolids C application remaining and accumulation while in phase two, SOC gain is due to biomass or C sequestration. Carbon sequestration changes with time relate to variations in biosolids application amounts (10 and 18 Mg ha-1 yr-1), different degradation rate constants (0.04yr-1 to 0.16yr-1), and biomass yields (35 to 40%). Additionally, comparison between model simulation results and laboratory resultsdetermine the amount of carbon sequestered in 41 strip-mined Illinois fields. The DRM application identifies two SOC phases in soil. Soil organic carbon gain in phase one (first 10 yrs) is primarily due to biosolids C application remaining and accumulation while in phase two, SOC gain is due to biomass or C sequestration. Carbon sequestration changes with time relate to variations in biosolids application amounts (10 and 18 Mg ha-1 yr-1), different degradation rate constants (0.04yr-1 to 0.16yr-1), and biomass yields (35 to 40%). Additionally, comparison between model simulation results and laboratory resultsdetermine the amount of carbon sequestered in 41 strip-mined Illinois fields. The DRM application identifies two SOC phases in soil. Soil organic carbon gain in phase one (first 10 yrs) is primarily due to biosolids C application remaining and accumulation while in phase two, SOC gain is due to biomass or C sequestration. Carbon sequestration changes with time relate to variations in biosolids application amounts (10 and 18 Mg ha-1 yr-1), different degradation rate constants (0.04yr-1 to 0.16yr-1), and biomass yields (35 to 40%). Additionally, comparison between model simulation results and laboratory resultsdetermine the amount of carbon sequestered in 41 strip-mined Illinois fields. The DRM application identifies two SOC phases in soil. Soil organic carbon gain in phase one (first 10 yrs) is primarily due to biosolids C application remaining and accumulation while in phase two, SOC gain is due to biomass or C sequestration. Carbon sequestration changes with time relate to variations in biosolids application amounts (10 and 18 Mg ha-1 yr-1), different degradation rate constants (0.04yr-1 to 0.16yr-1), and biomass yields (35 to 40%). Additionally, comparison between model simulation results and laboratory results provided by a yearlong study indicates that higher temperatures and moisture content and finer soils are related to larger degradation rates. To summarize, this study has the following contributions: (1) developed a degradation rate model which simulates the biosolids degradation process in soil and identifies two SOC phases in soil, and quantifies the biosolids degradation rate constant, biomass yield, and the C sequestered amount for multiple and long term soil application; (2) assessed the effect of changes in the amount of biosolids applied, soil type, and weather conditions on the C degradation rate by comparing model results to laboratory data; and (3) provides an easy quantitative method for predicting C sequestration from biosolids added to soil.
Ph.D. in Environmental Engineering, May 2016
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- Title
- EFFECT OF TEMPERATURE, MOISTURE CONTENT AND SOIL SURFACE AREA ON THE BIOLOGICAL DEGRADATION OF BIOSOLIDS ADDED TO SOIL
- Creator
- Wen, Dongqi
- Date
- 2016, 2016-05
- Description
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The objective is to develop and apply an organic matter degradation model (OMDM) that predicts changes in the biological degradation of...
Show moreThe objective is to develop and apply an organic matter degradation model (OMDM) that predicts changes in the biological degradation of organic matter added to soils as a function of soil temperature, moisture content and mineral surface area using data from field and laboratory measurements. A one year long laboratory study was conducted to determine biosolids microbial degradation rates (21 ˚C and 20% moisture content) for soils from eight different fields Biosolids microbial degradation rates were also determined for the eight soils under field condition (10 ˚C and 10% moisture content) by applying a degradation rate model (DRM). The total mineral surface areas for 27 soil samples were also determined. Regression analysis revealed that the degradation rate was positively associated with mineral soil surface area (R2=0.85) and that the biosolids application rate is not significantly associated with the biosolids degradation rate (p value =0.35>0.01). The OMDM determines a decomposition rate of 1.04 yr-1 at 30 ˚C, 20% moisture content, and 10 m2/g soil and provides correction factors for changes in soil temperature, moisture, and mineral surface area. The model predicted in changes of the biological degradation rate of biosolids added to soils with mineral surface areas that vary from 1 to 10 m2/g soil under laboratory and field conditions. A comparison of the measured and simulated degradation rates for eight different soils produced R2 = 0.87 for field data. The model was also able to predict the degradation rate of biosolids for 19 additional soils under field conditions (R2=0.89). The model was also applied to agricultural plant litter. The estimated degradation rates are 0.45 yr-1 corn stover, 0.35 yr-1 oats, 0.26 yr-1 wheat, and 0.13 yr-1 millet at 30 ˚C, 20% moisture content and 10 m2/g. This study demonstrates that the effects of environmental conditions and soil mineral surface area have a significant impact on degradation rates of organic matter and must be considered when assessing degradation rates for organic matter added to soil. Higher temperatures and moisture content and finer soils are related to larger degradation rates.
Ph.D. in Environmental Engineering, May 2016
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- Title
- DEVELOPMENT OF A NEW EMERGENCY EVACUATION SYSTEM FOR MINES
- Creator
- Qian, Qingyi
- Date
- 2011-08, 2011-07
- Description
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Underground mining is a very high risk industry. There are many potential hazards in the underground mining these include fire, explosion,...
Show moreUnderground mining is a very high risk industry. There are many potential hazards in the underground mining these include fire, explosion, inundation, roof collapse, toxic gases, chemical pollution, etc. Over past centuries, in US alone, more than 100,000 miners lost their life in different accidents. The primary safety methods used in underground mines concentrate on the monitoring of the hazardous gases, fire detection and ventilation. Using advanced instruments and monitoring techniques have significantly reduced the accidents in the modern mines. However despite the advancement of these monitoring facilities, accidents still occur in underground mining annually around the world, and many miners were killed because they were trapped and unable to escape due to blocked of exit access. This thesis describes a new development of an emergency evacuation system in underground mines and analyzes the advantages and disadvantages of the system. It is expected that the new system will greatly improve the emergency exit methods and save more lives in the future. The new emergency evacuation system consists of vertical concrete mineshaft, high capacity mineshaft elevators, surface terminal and underground support structures. In addition, the study of numerical simulation was carried out to observe the ground response during excavation. A typical ground profiles for underground mining in south part of China was used in this analysis. The results selected from shaft excavation simulation indicate that fluid drilling method effectively prevents the soil around mineshaft from collapse hazard. Compared to soil strength, soil stiffness has a significant influence on the soil response induced by excavating shafts.
Ph.D. in Civil Engineering, July 2011
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- Title
- OPTIMAL DECISION-MAKING OF INTERDEPENDENT TRANSPORTATION INVESTMENT ALTERNATIVES UNDER RISK AND UNCERTAINTY
- Creator
- Zhou, Bei
- Date
- 2012-07-12, 2012-07
- Description
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With increasing demand for a more efficient transportation system and decreasing budget levels, transportation investment decision-making that...
Show moreWith increasing demand for a more efficient transportation system and decreasing budget levels, transportation investment decision-making that aims to select the optimal project portfolio which yields maximized overall networkwide benefits in terms of economy, society and environment has increasingly become important. This dissertation has conducted an in-depth investigation into project evaluation and project selection that are crucial steps of transportation decision-making. It begins with information search through a review of existing methods for project evaluation and selection. Several limitations of existing methods have been revealed. In particular, they are in lack of considerations in network impacts of a single investment project, interdependencies of simultaneously implementing multiple projects, and restrictions of total risk of overall benefits of selected projects within an acceptable level. Then, a new methodology is proposed for networkwide traffic assignments, project evaluation, and project selection. A state-of-art large scale transportation simulation software, the TRansportation ANalysis and SIMulation System (TRANSIMS) toolbox, is utilized to perform networkwide dynamic traffic assignments to general redistributed traffic volumes after project implementation needed as inputs for project evaluation. For project evaluation, a life-cycle cost analysis approach is developed to consider all agency costs and user costs in the service life-cycle of two primary categories of highway facilities: pavements and bridges. In order to enhance the robustness of analytical results, risk and uncertainty of input factors concerning traffic volumes, project costs, and discount rates are incorporated into the life-cycle cost computation using @Risk Palisade software, Version 5.5. For project selection, two-stage enhanced Knapsack model, hypergraph Knapsack, and two-stage hypergraph Knapsack model are proposed to choose the best sub-collection of interdependent projects to yield maximized overall benefits at various budget levels, while controlling the total risk within an acceptable level. In terms of two-stage Knapsack model, the Markowitz mean-variance model is utilized for stage-one optimization to generate minimized total risk of all projects subject to constraints of available budget and minimum benefits to be expected for individual projects. At the second stage, the Knapsack model is enhanced by adding stage-one optimization solution as one more constraint. Such a treatment could help control the total risk of overall benefits of all selected projects at a desirable level. Moreover, a hypergraph Knapsack model is introduced to capture project network impacts and interdependency relationships. In order to simultaneously address issues of networkwide project impacts, interdependencies, and total risk levels, a two-stage hypergraph Knapsack model is developed. Efficient solution algorithms are developed and coded to Frontline Solver Xpress V55 software to solve the two-stage Knapsack model, hypergraph Knapsack model, and two-stage hypergraph Knapsack model, respectively. Three computational studies are performed to apply the proposed methodology using two sets of data, including six-year data on 672 candidate projects proposed by Indiana Department of Transportation for state highway programming and 6 mega projects proposed by Illinois State Toll Highway Authority for tollway network major capital improvements. It has generally found that the use of two-stage Knapsack model could readily control the total risk of overall benefits of selected projects at a desirable level, but it may result in significant changes in the overall benefits for different budget levels where significant differences in risks are associated with individual projects. The hypergraph Knapsack model could effectively handle issues of networkwide project impacts and interdependency relationships. However, the two-stage hypergraph Knapsack model appears to be most robust in that it could simultaneously resolve the issues of networkwide project impacts, interdependency relationships, and total risks of overall project benefits, thus generating most reliable information to support rational transportation investment decision-making.
Ph.D. in Civil Engineering, July 2012
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- Title
- MONITORING, MODELING, AND TREATMENT OF ODORS/ODORANTS AT WATER RECLAMATION PLANTS
- Creator
- Zhang, Yanming
- Date
- 2012-04-23, 2012-05
- Description
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A thorough study including odor monitoring, modeling and treatment as three important aspects of odor control in WRPs has been performed in...
Show moreA thorough study including odor monitoring, modeling and treatment as three important aspects of odor control in WRPs has been performed in this research. Measurement of H2S emissions from odor sources was proven to be an essential step in odor monitoring program. The H2S emission rates were measured from various sources throughout a WRP for 9 sampling events during winter and summer. During summer, both the average and the maximum emission rates of H2S from liquid treatment processes increased significantly compared to those measured during winter. However, for solids-handling processes, the emission rates remained constant because sludge characteristics did not vary throughout the year. The total sulfide concentrations present in liquid treatment processes were higher than those in preliminary and primary treatment units but at much lower levels in secondary treatment. Rates of H2S emission from the headworks were correlated to daily average wastewater temperature, TKN concentration, and flow rate. AERMOD was used as the modeling tool to evaluate the odor impact of Egan WRP on the surrounding communities. The emission rates could significantly affect the modeling results. Long-term H2S monitoring increases the possibility of developing the proper emission rate for the worst-case scenario. Excluding the modeling during the night would avoid overestimation of odor impact and excessive odor control. In the laboratory-scale study of O3 oxidation of H2S, O3 oxidation was proven to be a fast and effective method to remove H2S from the odorous air emitted from wastewater treatment processes. The increased initial ratio of O3/H2S enhances the removal rate of H2S. The consumption ratio of O3/H2S is a function of input reactant ratios. A multiple linear regression model (R2=0.84) has been developed to predict the H2S residual for given initial H2S and O3 concentrations and reaction time. The increased moisture content of the odorous air enhanced the H2S removal while DMS and DMDS inhibit H2S removal by competing for the limited O3 supply.
Ph.D. in Environmental Engineering, May 2012
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- Title
- Development and Application of an Occupational Odor Hazard Index
- Creator
- Wang, Tingting
- Date
- 2011-04-24, 2011-05
- Description
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Odors emitted from wastewater treatment and sludge processing facilities may lead to employee complaints regarding discomfort, stress or...
Show moreOdors emitted from wastewater treatment and sludge processing facilities may lead to employee complaints regarding discomfort, stress or disease, and affect productivity and worker turnover in Water Reclamation Plants (WRPs). This study reports and assesses a comprehensive method that estimates the odor perception and associated hazards from exposures to odors in a post-digestion dewatering building in a WRP and its vicinity areas. An Odor Reference Concentration (ORfC) is developed as an index of acceptable odor level. This index is applied to ensure that the majority of building occupants (80 percent or more) do not perceive the odor. This index is developed to fill the lack of a uniform standard and method to assess hazard of exposed individuals to odors in occupational environments and to regulate odor exposures.A comprehensive odor and odorant concentration database was formulated by a monitoring study in the occupational environment of a post-digestion dewatering building. The presence of odorants in the building are at concentrations below occupational exposure limits but higher than odor detection threshold values. This finding indicates that reducing odorant concentrations below exposure limits does not assure an odor-free environment. A model is formulated and validated for this dewatering building associating odor perception with concentrations of total sulfur compounds and relative humidity and is used for prediction of indoor odor concentrations under various conditions. Odor and odorant emission rates as the strength of sources are input variables of the indoor air quality model. In this study, odor and odorant emission rates from freshly dewatered biosolids in a dewatering building were measured using two widely used dynamic methods: the USEPA flux chamber and wind tunnel, and results from the two methods are not significantly different. Comparison of the two methods indicates that both methods can be used to estimate odor and odorant emission rates but the most effective and efficient method depends on prevailing environmental conditions. The ORfC established based on the comprehensive odor and odorant concentration database for this dewatering building is 13D/T (dilution to threshold). This index is used to evaluate seven control strategies recommended to reduce odor levels. If indoor odor concentrations in the occupational environment exceed the ORfC, then the hazard of odor exposures is unacceptable. Deterministic results of this study indicate that if appropriate control strategy is applied, odor concentration in the dewatering building would reach to below levels that cause unnecessary stress and other effects. The control strategy focus of this work is reduction of the indoor odor perception. But indoor control strategies must not cause outdoor odor problems to surrounding residential areas. Therefore, the potential impact of the control strategy recommended is also investigated in this thesis using the US EPA recommended air dispersion modeling AERMOD. Predictions of hydrogen sulfide concentrations at surrounding areas of the plant indicate that only one strategy, which proposes to add a new exhaust system in the dewatering building, would cause the ambient hydrogen sulfide concentration to be 7% higher than the odor detection threshold; other six strategies would not induce odor annoyance to surrounding areas. Acute and long-term ambient hydrogen sulfide exposure limits based on human health and irritation effects would not be violated under any of the seven control strategies.
Ph.D. in Environmental Engineering, May 2011
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- Title
- PIEZO-BARKHAUSEN PULSE SIGNAL ANALYSES (BPSA) AND DETERMINATION OF THE FATIGUE LIFE OF AISI-1018 STEEL NEAR THE ENDURANCE LIMIT
- Creator
- Nunez-moreno, Federico Alejandro
- Date
- 2014, 2014-05
- Description
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A series of fatigue tests were performed on two different types of steels named Steel A (annealed and decarbed AISI-1018 steel), and Steel B ...
Show moreA series of fatigue tests were performed on two different types of steels named Steel A (annealed and decarbed AISI-1018 steel), and Steel B (annealed and polished AISI-1018 steel), carried out to separation or to a maximum of 10,000,000 cycles (which was taken to be equivalent to infinite life). Strain levels ranging from 0.0014 in/in (0.0014mm/mm) down to 0.0008in/in (0.0008mm/mm) were used to execute all experimental load tests at a stress ratio R=-1 (complete reversal). An MTS machine was used for these trials. At the same time, magnetic fields and piezo-Barkhausen pulses were recorded by means of a flux gate magnetometer and a copper coil connected to a series of signal filters and amplifiers. Results were used to construct the classical S-N Whöler curve for both steels, as well as in exhibiting the behavior of the magnetic parameters (magnetic excursions, dominant frequencies of the magnetic signals) coupled to the fatigue lives of the samples tested. To describe such couplings, a set of correlations were introduced among the monitored variables as functions of testing time and applied strain. Also, a fractography analysis of the crack patterns using a scanning electron microscope was performed to represent statistically the geometry of “dimples” and fatigue striations from the inception of the crack, until the formation of a shear lip at the final stages of the crack. It was found that the magnitude of the mean amplitude of the piezo-Barkhausen pulses at early stages of the test is correlated to a mid-level energy of cracking, and thus explains the geometry of fatigue striations near the initiation of the crack at higher strain levels, compared to the geometry of the fatigue striations at lower strain levels. x xvi A joint analysis of the amplitudes of the magnetic excursions recorded in time, and the dominant frequencies of the magnetic signals were found to be discriminators of the elastic and plastic behavior of both types of steel. Furthermore the observed magnetic parameter variations determined in a clear way the endurance limit for each type of steel; these values also are in agreement with the strain level for which fatigue lives were greater than 10,000,000 cycles. Based on these results a “bell analogy” for interpreting the fatigue behavior is introduced. Bridge engineering applications and further research is also discussed.
PH.D in Civil Engineering, May 2014
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- Title
- CYBER-PHYSICAL SYSTEM FOR A WATER RECLAMATION PLANT: BALANCING AERATION, ENERGY, AND WATER QUALITY TO MAINTAIN PROCESS RESILIENCE
- Creator
- Zhu, Junjie
- Date
- 2015, 2015-07
- Description
-
Aeration accounts for a large fraction of energy consumption in conventional water reclamation plants (WRPs). Although process operations at...
Show moreAeration accounts for a large fraction of energy consumption in conventional water reclamation plants (WRPs). Although process operations at older WRPs can satisfy effluent permit requirements, they typically operate with excess aeration. More effective process controls at older WRPs can be challenging as operators work to balance higher energy costs and more stringent effluent limitations while managing fluctuating loads. Therefore, understandings of process resilience or ability to quickly return to original operation conditions at a WRP are important. A state-of-art WRP should maintain process resilience to deal with different kinds of perturbations even after optimization of energy demands. This work was to evaluate the applicability and feasibility of cyber-physical system (CPS) for improving operation at Metropolitan Water Reclamation District of Greater Chicago (MWRDGC) Calumet WRP. In this work, a process model was developed and used to better understand the conditions of current Calumet WRP, with additional valuable information from two dissolved oxygen field measurements. Meanwhile, a classification system was developed to reveal the pattern of historical influent scenario based on cluster analysis and cross-tabulation analysis. Based on the results from the classification, typical process control options were investigated. To ensure the feasibility of information acquisition, the reliability and flexibility of soft sensors were assessed to typical influent conditions. Finally, the process resilience was investigated to better balance influent perturbations, energy demands, and effluent quality for long-term operations. These investigations and evaluations show that although the energy demands change as the influent conditions and process controls, in general, aeration savings could be up to 50% from the level of current consumption; with a more xix complex process controls, the saving could be up to 70% in relatively steady-state conditions and at least 40% in relatively challenging transient conditions. The soft sensors can provide reliable and flexible performance on target predictions. The plant can still maintain at a similar level of process resilience after 50% aeration saving, even during long-term perturbations. Overall, this work shows that it is well feasible to provide more cost-effective operations at the Calumet WRP, and meanwhile influent perturbations, effluent quality, and process resilience are well in balance. Keywords: Energy, aeration, effluent quality, perturbation, resilience, water reclamation plant.
Ph.D. in Environmental Engineering, July 2015
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- Title
- AN INTRINSICALLY CONDUCTING POLYMER-BASED COATING SYSTEM FOR CORROSION PROTECTION OF STEELS
- Creator
- Yu, Qifeng
- Date
- 2016, 2016-12
- Description
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Among the various corrosion protection strategies for structural steels, coating techniques provide the most cost-effective protection and...
Show moreAmong the various corrosion protection strategies for structural steels, coating techniques provide the most cost-effective protection and have been used as the primary mode for corrosion protection. Existing coating techniques have been used mainly for their barrier capability and all have a limited service life. In this research work, a waterborne two-strand polyaniline: poly (acrylic acid) complex was synthesized and utilized to fabricate the primer layer of a two-layer coating system. The techniques of Scanning Kelvin Probe Force Microscopy (SKPFM) and Electrochemical Impedance Spectroscopy (EIS) were used to evaluate the anti-corrosion capability of the polymeric complex when mixed in an epoxy matrix and coated on steel samples as the primer layer. The evaluation results show that coating systems including a PANi-based primer has measurable anticorrosion capability and the anti-corrosion capability of PANi-based primer depends on the usage of PANi and the type of matrix material of the primer layer. In the laboratory condition, a prototype two-layer coating system including the PANi-based primer and a polyurethane topcoat was manufactured. The ASTM Salt-Spray Test and EIS were used to prove the anti-corrosion performance of the prototype using a two-layer, polyurethane-over-epoxy system (no PANi) as the control system. After the proof of concept, a non-waterborne epoxy was used to fabricate a different PANi-based primer. The two types of primers and two other commercial primers (a zinc-rich primer and an epoxy-only primer) were used to make a total of eight two-layer coating systems using two widely used topcoats. Salt-Spray Test, Cyclic Salt Fog/UV Exposure Test, Pull- Off Adhesion Test, and the techniques of EIS, SKPFM, and Scanning Electron Microscope (SEM) were used to evaluate the long-term performance of the eight systems. Based on the laboratory-based recommendations, six groups of two-layer coating systems were then subjected to the outdoor-exposure test to evaluate their anti-corrosion durability at two testing sites. The field durability of the coating systems was evaluated in terms of their surface gloss reduction, color change, adhesion change and surface deteriorations. The matrix material in which the PANi is mixed plays an important role in the longterm anti-corrosion performance of coatings. The waterborne epoxy is effective in dispersing PANi nano-particles and has zero VOC; however, it does not bond to the steel surface as strongly as the regular non-waterborne epoxy. The topcoat material also plays an important role in the long-term anti-corrosion performance of coatings; polyurethane has higher durability than epoxy as a topcoat material. The PANi-based systems possess long-term corrosion protection comparable to the performance of the conventional zincrich three-layer system based on the one-year field evaluation.
Ph.D. in Civil Engineering, December 2016
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- Title
- AUTOMATED PROGRESS CONTROL USING LASER SCANNING TECHNOLOGY
- Creator
- Zhang, Chengyi
- Date
- 2013, 2013-05
- Description
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Assessing progress in different construction activities at the end of every payment period is time consuming and requires specialized...
Show moreAssessing progress in different construction activities at the end of every payment period is time consuming and requires specialized personnel employed by the contractor and the owner. Automatic progress control that requires a minimum amount of human involvement could reduce the time spent on this activity, reduce the number of personnel used, reduce the cost involved, reduce disagreements between contractor and owner, and add to the overall efficiency of project management. Attempts have been made in the past to resolve this issue using image processing and other techniques but the results have not been satisfactory. A new attempt was made to set up a system that can assess progress control with minimum human input and the results are presented in this paper. The experiment made use of laser scanning technology and was conducted both in laboratory conditions and construction sites. The initial results from laboratory condition appear to be promising but there are still obstacles to surmount. The system is robust and accurate in laboratory conditions and constitutes proof of concept. Improvements are made to accelerate the registration process of multiple scans, to reduce the noise data, to recognize objects of irregular shape, and to assess the practicality and economic feasibility of such a system when applying this system in real construction sites. Keywords: Construction scheduling, progress control, laser scanning
PH.D in Civil Engineering, May 2013
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- Title
- LONG-TERM AEROBIC AND ANAEROBIC TRANSFORMATIONS OF ORGANIC MATTER IN ANAEROBICALLY DIGESTED BIOSOLIDS
- Creator
- Lukicheva, Irina
- Date
- 2012-12-05, 2012-12
- Description
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Long-term anaerobic storage of biosolids in a lagoons type of system as a post-treatment to anaerobic digestion is a proven process for...
Show moreLong-term anaerobic storage of biosolids in a lagoons type of system as a post-treatment to anaerobic digestion is a proven process for further pathogen reduction to produce Class A biosolids. At the same time, final biosolids product could develop odors during storage and handling, limiting the flexibility of biosolids utilization. The goal of this research was to study properties of biosolids under different lengths of aging time to determine the stability of final product for its odor potential. Field lagoons of Metropolitan Water Reclamation District of Greater Chicago were sampled to estimate the spatial and temporal variations in the physical-chemical properties and biological stability indicators, namely, total solids, volatile solids, pH, electric conductivity, total Kjeldahl nitrogen, ammonia-N, nitrite/nitrate-N, accumulated oxygen uptake for the 20-hour respirometric test, soluble protein concentration and headspace concentrations of volatile sulfur compounds. The sampling campaign was performed in October 2009. Two types of lagoons were assessed in this study- high-solids lagoons that are loaded with sludge that was previously anaerobically digested and dewatered on the centrifuges, and low-solids lagoons that are loaded with sludge that was previously digested but not dewatered. The analysis of collected data suggested that for the high-solids lagoons the surface layer biosolids (depth of above 0.15 m) undergo long-term aerobic oxidation resulting in higher degree of final product stabilization. The subsurface layers (depth below 0.15 m) are subjected to anaerobic environment where the conditions allow only the initial rapid organic matter degradation approximately within the first year, followed xii by very slow degradation. In addition, microbiological analyses using Fluorescent in situ Hybridization did not indicate active microbial communities in aged biosolids. The performance of low-solids lagoons in the reduction of the biodegradability parameters was shown to be similar to that of the high-solids lagoons. Low-solids lagoons were shown to perform the dewatering function reducing moisture in the digested sludge from initial 2-3% TS to up to 16% TS. Although the lagoon aged biosolids were found to be stable in comparison with other products, such as composts, further aerobic processes taking place after lagoons, such as air-drying and stock-piling could induce further active biological activity. This could potentially result in the odor formation from the air-dried final product. For these reasons, more research is required on the mechanisms promoting further product degradation after lagoons aging.
PH.D in Environmental Engineering, December 2012
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- Title
- ADVANCING DESIGN SIZING AND PERFORMANCE OPTIMIZATION METHODS FOR BUILDING INTEGRATED THERMAL AND ELECTRICAL ENERGY GENERATION SYSTEMS
- Creator
- Zakrzewski, Thomas
- Date
- 2017, 2017-07
- Description
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Combined electrical and thermal energy systems (i.e., cogeneration systems) will play an integral role in future energy supplies because they...
Show moreCombined electrical and thermal energy systems (i.e., cogeneration systems) will play an integral role in future energy supplies because they can yield higher overall system fuel utilization and efficiency, and thus produce fewer greenhouse gas emissions, than traditionally separate systems. However, methods for both design sizing and performance optimization for cogeneration systems and commercial buildings lag behind the tremendous advancements that have been made in building performance simulation methods. Therefore, the overall goal of this research is to develop and apply novel cogeneration system modeling techniques for optimizing design sizing and dispatch of generation sets that reduce energy use, energy costs, and greenhouse gas emissions. This research is divided into four main research objectives: (1) generalizing cogeneration performance of lean burn natural gas spark ignition reciprocating engines, (2) developing a new Design and Optimization of Combined Heat and Power (DOCHP) systems optimization tool for improving design-sizing of building-integrated and grid-tied CHP systems, (3) demonstrating the utility of the DOCHP tool with several practical applications, and (4) integrating on-site intermittent renewable energy systems into the DOCHP tool to analyze micro-grid applications. This research leverages recent developments in multiple areas of building and system simulation methods. DOCHP advances design sizing and performance optimization methods for building integrated thermal and electrical energy generation systems through the application of an evolutionary artificial intelligence-based genetic algorithm and its ability to resolve to non-linear optimization with discrete constraints while considering non-linear part-load generation set performance curves.
Ph.D. in Civil Engineering, July 2017
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- Title
- NON-LINEAR CREEP-RELAXATION CONSTITUTIVE MODEL FOR PLAIN CONCRETE WITH ANISOTROPIC DAMAGE
- Creator
- Teran Torres, Bernardo
- Date
- 2016, 2016-05
- Description
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A thermodynamic constitutive model for plain concrete, and other quasi-brittle materials, is developed. The model accounts for the anisotropic...
Show moreA thermodynamic constitutive model for plain concrete, and other quasi-brittle materials, is developed. The model accounts for the anisotropic damage-induced and the aging viscoelasticity of the material. The model is based on the theory of solidi cation proposed by Baºant and the continuum damage mechanics theory. The material is considered to be a viscoelastic-damageable material. The Helmholtz free energy utilized in the formulation is treated by means of the representation theorem of coupled damage-strain tensors. The model is capable of analyzing time-dependent damage (tertiary creep) under constant loading and damage due to cyclic creep. Two simple but practical examples are presented in order to illustrate the applicability of the model. The determination of the functions and constants representing the material behavior as well as any experimental companion is proposed for the continuation of the research.
Ph.D. in Civil Engineering, May 2016
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- Title
- IMPACT OF WORK FLOW DISRUPTIONS, PROJECT CHARACTERISTICS AND FOREMEN CHARACTERISTICS ON IMPROVISATIONAL DECISIONS AND ACTIONS ON CONSTRUCTION SITES
- Creator
- Kleps, Stephen M.
- Date
- 2013, 2013-12
- Description
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Disruptions on construction sites are a constant issue and unfortunately can have negative impacts on the workflow and productivity of the...
Show moreDisruptions on construction sites are a constant issue and unfortunately can have negative impacts on the workflow and productivity of the impacted crews. As a result of these disruptions, foremen must quickly generate improvised solutions to the disruptions to keep the work of their crew progressing. Yet the mechanics of how exactly this improvisational decision making is occurring has not been previously studied. To address this void in the literature, this study examined the factors that may influence a foremen's ability to improvise, such as the type of disruption, the jobsite characteristics, and the personality, experience, and education of the foremen, in relation to the level of improvisation occurring. To accomplish this, this study collected data from 50 foremen within the electrical construction industry to measure to what degree they improvised and with what speed they improvised in response to their daily disruptions, resulting in 244 recorded disruption incidents. In analyzing these incidents with multilevel modeling analysis techniques, it was determined that the type of disruption did not have as large of an effect on the degree and speed of the resulting improvisation as originally hypothesized. In addition, it was found that factors such as the level of cooperation on the job site, the time pressure on the foremen, and the level of collaboration on the job site influenced the degree and speed of the improvisation. Yet the factors that explained the largest total variance in both the degree and speed of improvisation were the personality traits of the foremen. Thus, these findings emphasize the importance of foremen on job sites, while also documenting how improvisation is occurring on job sites.
PH.D in Civil Engineering, December 2013
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- Title
- LIVE LOAD FACTORS FOR CONTINUOUS GIRDER BRIDGES
- Creator
- Wang, Qing
- Date
- 2016, 2016-07
- Description
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Live load factors of Strength I limit state for continuous girder highway bridges are calibrated based on reliability concept adopted by...
Show moreLive load factors of Strength I limit state for continuous girder highway bridges are calibrated based on reliability concept adopted by AASHTO LRFD and LRFR specifications. A uniform reliability is maintained for multi-girder highway bridges with various span lengths. WIM data, gathered by California, Michigan, New York, Oregon, and Illinois State Department of Transportation are analyzed. Live load effects produced by WIM data are calculated using influence lines. Expected maximum live load effects in given periods are modeled and extrapolated by Gumbel distribution. A relativecalibration formula is developed in order to derive live load correction factors for designing/evaluating continuous highway bridges at a reliability level that is in consistent with simply supported highway bridges. Computer programming is conducted for data sorting and traffic statistical analysis.
Ph.D. in Civil Engineering, July 2016
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- Title
- INFLUENCE OF OWNER-ORGANIZATION IMPRESSION AND CONTRACT FRAMING ON CONSTRUCTION CONTRACTORS' RISK PERCEPTIONS
- Creator
- Hanioglu, Mehmet Nihat
- Date
- 2014, 2014-12
- Description
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In a construction project, it is generally accepted that the contractor's perceived risk is the main factor in determining what is to be...
Show moreIn a construction project, it is generally accepted that the contractor's perceived risk is the main factor in determining what is to be proposed as the project cost and duration. Both the owner-organization and the contractor are aware of the existing risks and the owner-organizations tend to mitigate the existing risks by using the construction contract. It is hypothesized that the contractor’s initial impression of the owner-organization is a factor in the contractor’s perception of risk. It is further hypothesized that the initial impression is influenced by the content and context of the construction bid documents, which further influences the perceived risk and the bid strategy. The goal is to investigate the factors that influence contractors' impression of the owner-organization and to study the effects of contract document language and content in the impression formation process and subsequent development of a bid strategy. By better understanding the factors and relationships that influence impression formation and risk perceptions, it is expected that substantial time, money and unnecessary contention between these parties can be eliminated.
Ph.D. in Civil Engineering, December 2014
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- Title
- NETWORK-LEVEL VEHICLE CRASH PREDICTIONS INCORPORATING TIME-DEPENDENT EFFECTS INTO CONSIDERATIONS
- Creator
- Dao, Hoang
- Date
- 2016, 2016-07
- Description
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Maintaining highway safety is viewed as the over-arching goal of mananging transportation systems at all levels. According to the National...
Show moreMaintaining highway safety is viewed as the over-arching goal of mananging transportation systems at all levels. According to the National Highway Traffic Safety Administration (NHTSA), over 37,000 people got killed and 2.35 million are injured in road crashes annually. The equivalent economic and societal losses are on the order of over $231 billion, or an average of $820 per person. Thus, developing vehicle crash models that can accurately predict crash occurrences becomes essential. The study begins with literature review of models for predicting vehicle crash frequencies and crash severity levels on highway segments and at highway intersections. The findings of literature review indicate that some models lack prediction accuracy owing to exclusion of many crashing contributing factors. Consequently, a new methodology for improved vehicle crash predictability is proposed to include as many crash contributing factors as possible. In addition, the proposed methodology aims to conduct crash predictions targeting a highway network. Two computational experiments are performed for methodology application, including one on highway segment-related crash predictions using data on Highway Safety Information System for Illinois from 2001 to 2010, and another one on intersection-related crash predictions using crash data on more than one thousand intersections for period 2004 to 2010 provided by city of Chicago. Cross comparisons are made on the results obtained by applying the proposed methodology, method documented in Highway Safety Manual (AASHTO, 2010), and Empirical Bayesian (EB) before-after method for validation. The proposed methodology is found to have out-performed the other two methods. Future research directions are provided for continuing refinements of the proposed methodology.
Ph.D. in Civil Engineering, July 2016
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- Title
- COORDINATED DRIVING IN CONNECTED AND AUTONOMOUS VEHICLE SYSTEM -- OPTIMAL ADVANCE LANE CHANGE ZONES AND COORDINATED PLATOON CAR FOLLOWING CONTROL
- Creator
- Gong, Siyuan
- Date
- 2017, 2017-07
- Description
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The connected and autonomous vehicle (CAV) system enables countless innovative coordinated driving approaches, such as coordinated lane change...
Show moreThe connected and autonomous vehicle (CAV) system enables countless innovative coordinated driving approaches, such as coordinated lane change and car-following in microscopic CAV control, and coordinated rounding and parking in macroscopic traffic flow guidance, which will improve the performance of our transportation system by enhancing traffic mobility, providing safe driving environment and reducing fuel consumption. Since the lane change and car-following behavior are indicated as crucial factors of traffic safety and efficiency, this dissertation focuses on developing the coordinated driving schemes in microscopic control and operation of lane change and car-following maneuvers. In particular, I develop an lane change zone optimization strategy and the coordinated platoon car-following control for a pure CAV platoon and a mixed platoon (i.e. mixed with human-drive vehicles and CAVs) respectively. This dissertation first explore the management strategy of the mandatory lane change near a two-lane highway off-ramp by optimizing the location of advance warning. The proposed approach considers that the area downstream of the advance warning includes two zones: the green and yellow zones corresponding to their respective most like lane change maneuvers. An optimization model is proposed to search for the optimal green and yellow zones. Traffic flow theory such as Greenshield model and shock wave analysis are used to analyze the impacts of the S-MLC and D-MLC maneuvers on the traffic delay. Numerical experiments indicate that the proposed optimization model can identify the optimal location to set the advance MLC warning nearby an off-ramp so that the traffic delay resulting from lane change maneuvers is minimized, and the corresponding capacity drop and traffic oscillation can be efficiently mitigated. Then, this research develops a novel car-following control scheme for a platoon of connected and autonomous vehicles on a straight highway. The platoon is modeled as an interconnected multi-agent dynamical system subject to physical and safety constraints. A constrained optimization based control scheme is proposed to ensure an entire platoon’s transient traffic smoothness and asymptotic dynamic performance. This dissertation develops dual based distributed algorithms to compute optimal solutions with proven convergence. Furthermore, the asymptotic stability of the unconstrained linear closed-loop system is established. These stability analysis results provide a principle to select penalty weights in the underlying optimization problem to achieve the desired closed-loop performance for both the transient and the asymptotic dynamics. By the motivation that CAVs and human-drive vehicles will co-exist on the road for a long period in the near future, the third part of this dissertation extends the pure CAV coordinated platooning control to the mixed flow environment. By integrating the Newell car-following model, a real-time curve matching algorithm is implemented to calibrate the ca-following model and anticipate the movement of human-drive vehicle by the real-time trajectory data. The constrained MPC are developed for each CAV platoon, considering their movement interaction through the human-drive vehicle platoon. Furthermore, this study provide a modified dual based distributed algorithm to improve convergence speed of the primal problem for the dual based distributed algorithm in Chapter 4. Several requirements of the penalty weights selection are provided by stability analysis under the unconstrained conditions. The numerical experiments based on field data will be conducted to illustrate the effectiveness and efficiency of the proposed the solution approach and the platoon control schemes.
Ph.D. in Civil Engineering, July 2017
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- Title
- DYNAMIC ANALYSIS OF UNCERTAIN STRUCTURES USING IMPRECISE PROBABILIY
- Creator
- Bergerson, Joshua D.
- Date
- 2014, 2014-05
- Description
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A new method for dynamic response spectrum analysis of structures with uncertainty in their mechanical properties utilizing the notion of...
Show moreA new method for dynamic response spectrum analysis of structures with uncertainty in their mechanical properties utilizing the notion of imprecise probability is developed. This finite-element-based method is capable of obtaining probabilistic bounds of the dynamic response of the structure with uncertainty defined by enveloping p-boxes. The developed method obtains probabilistic bounds on 1) the mode shapes, 2) modal coordinates, and 3) modal participation factor, leading to the p-boxes of modal responses. Finally maximum modal responses are combined to obtain the structure’s maximum total response with consideration of uncertainty. Numerical examples demonstrating the developed method are included. Keywords: Structural Dynamics, Uncertainty, Imprecise Probability, P-Box.
PH.D in Civil Engineering, May 2014
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