Ph.D. - Civil Engineering

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    Ambient Energy Harvesting-An Electrostatic Approach.
    ( 2018-08) Yu, Jian ; Civil Engineering
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    A Landslide Warning System For a Soil Slope on Oahu.
    ( 2018-05) Iwamoto, Melia K. ; Civil Engineering
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    Comprehensive method for evaluating signalized intersections treatments : left turn prohibition and partial grade separation
    ([Honolulu] : [University of Hawaii at Manoa], [May 2013], 2013-05) Yu, Xin
    This research proposes a three-level project decision-making process taking into account the planning and screening, feasibility and performance study, and evaluation and decision-making in the development of an intersection improvement project. A planning and screening level is to quantify and compare the benefits and costs LTP and LCUP was developed to examine the potential applicability of these congestion mitigation actions by examining intersection delay using the Highway Capacity Manual 2010, accident frequency using the Highway Safety Manual, and cost-benefit analysis based on AASHTO's User Benefit Analysis for Highways Manual, prior to conducting extended data collection and detailed analysis. Feasibility and performance analysis is to examine the feasibility of a treatment by considering site-specific constraints, and if feasible, conduct detailed performance analysis using advanced analysis tools. Five-stage multiple attribute evaluation under uncertainty and fuzziness (MAFU) process is proposed in evaluation and decision-making level, which is able to assess the magnitudes of intersection treatment performance and to the fuzziness in stakeholder preference and the uncertainty in performance measurement. MAFU is designed to determinate the alternative which can best achieve a compromise between all competing objectives and conflicting interests. It features fuzzy mathematics (FAHP) to capture the stakeholder preferences, utility function theory (MAUT) to combine performance measures and describe risk sensitivity, and probabilistic approach (MCS) to model output uncertainties and conduct the tradeoff analysis. A case study is provided to demonstrate the application of this integrated and comprehensive method and the reliability of using this method for project evaluation and decision-making.
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    Developing Tools for Earthquake-induced Landslide Hazard Maps of the Island of Hawaiʻi
    ([Honolulu] : [University of Hawaii at Manoa], [December 2013], 2013-12) Namekar, Shailesh Arun
    The purpose of this study is to develop earthquake-induced landslide hazard maps for the Island of Hawaiʻi using various tools such as Geographical Information Systems (GIS), Artificial Intelligence (AI), and Logistic Regression (LR). The methodology for the current research consists of developing empirical models based on factors considered to be most influential on landslide susceptibility, and analytical models based on conventional slope stability analysis. Earthquake-induced landslide hazard maps were then developed using these models for the Island of Hawaiʻi. Empirical models involve systematically studying the landslide contributing factors for the entire island without using any slope stability model. This can be applied to the entire island with generally available island-wide spatial data. Empirical models involve the use of various techniques such as weight analysis, logistic regression and AI based tool such as ANFIS (Adaptive Neuro Fuzzy Inference System). In the weight analysis, different landslide contributing factors were grouped according to their relative importance. These weights were obtained and refined by an Artificial Neural Network (ANN). The map of the Island of Hawaiʻi was divided into cells of size 100m * 100m. Each landslide contributing factor was classified into a common evaluation scale of 1 to 10. Then, landslide contributing factors were multiplied by their respective weights. Finally, the results of the calculations (i.e. final rating values) were obtained. These final rating values were plotted with a color scheme in a map with ten zones of landslide vulnerability (viz., Red (High) (10) to Green (Low) (1). This map showed that weight analysis can locally yield "false positive results. Therefore, two empirical models were developed based on ANFIS and Logistic Regression. In LR-and ANFIS-based models, probability of failure was predicted using landslide contributing factors as inputs. Hazard status values, 0 (Low hazard, i.e. low probability of failure) to 1(High Hazard, i.e. high probability of failure), were derived. Based on these hazard status values, the potential hazard maps were developed. These potential hazard maps provided an overview of potential landslide hazard zones on the Island of Hawaiʻi where more detailed study may be warranted. Though empirical models developed here do not consider seismic analysis, they give a bigger picture of landslide hazard zoning (susceptibility) for the entire island. The maps developed using empirical models can help in selecting regions where further study on slope stability is necessary. For these selected regions, slope stability analysis was carried out with new empirical models developed using explanatory variables from an analytical slope-stability model. In latter models, the general approach to the landslide zoning method is based on conventional slope stability analyses to determine the Factor of Safety (FS) and critical ground (yield) acceleration (ay) of the individual slopes based on profiles and specific geotechnical and seismic information. Due to inadequate peak shear strength data for the studied regions, along with other considerations, a residual friction angle prediction model using ANFIS was developed based upon available data pairs of residual friction angle and available soil parameters for various locations around the world, including some in Hawaiʻi. The (or These) derived residual friction angle data were then used in slope stability analyses. The Peak Ground Acceleration (PGA) is the most commonly used ground motion parameter in seismic hazard assessment. PGA data at 2% exceedance probabilities in 50 years for the Island of Hawaiʻi (published by USGS) were used for the analyses. Here, probability of exceedance may be defined as probability that an event of specified magnitude will be equaled or exceeded in any defined period of time. Based upon the calculated difference between PGA and ay (yield acceleration), a hazard rating scale was developed. Using this scale, Earthquake-induced landslide hazard zoning maps with ten zones viz., high (1) to low (0), were developed. For the Island of Hawaiʻi, a new PGA prediction model was developed using ANFIS. This model can reconstruct the PGA for any historical earthquake or future hypothetical earthquake. Hence, PGA values for various historical earthquakes and one hypothetical earthquake were derived using ANFIS. Based upon the calculated difference between these PGA values and ay, earthquake-induced landslide hazard zoning maps with ten zones viz., high (1) to low (0), have been developed. These maps provide hazard status values for various geographically distributed earthquake scenarios. PGA is a model-derived parameter; hence errors in PGA prediction models are likely to be propagated in the calculated difference between PGA and ay. To minimize the propagation of errors in the PGA prediction model, the parameters used to develop PGA, slope and residual friction angle were related to the hazard status (1, High: Slide) and (0, low: No slide). Two independent seismic slope stability prediction models were developed based on slope, friction angle, earthquake magnitude, hypocentral distance and average shear wave velocity for earth material from the surface to a depth of 30m as inputs to predict the hazard status (1, High to 0, Low) using LR and ANFIS. The earthquake-induced landslide hazard maps developed using empirical and analytical models, supported by the historical earthquake-induced slide location database, show that North Kohala, Hamakua, and North Hilo have several areas with high hazard ratings. This reflects the abundant steep slopes, high rainfall conditions, weak soils, and weathered rock on these areas. The Island of Hawaiʻi has experienced post-earthquake soil and/or rock slope movements. The dataset required for rock slope stability analysis is sparse and incomplete for Hawaiʻi. Therefore, this study relied heavily on reviews of the literature. This review indicates that most rock slope failures were influenced by the presence of pyroclastic materials. Where pyroclastic material underlies massive basalt rocks, it tends to ravel downslope in seismic events thereby undermining the massive basalt blocks. The landslide hazard maps developed here can be utilized to prioritize further investigation and to highlight where further recommendations on mitigation methodologies may be appropriate. After establishing hazard zones on a landslide hazard map, a detailed site-specific study can be done and necessary slide preventive measures can be taken. The earthquake-induced landslide hazard zoning maps may provide valuable information on the slope stability of large areas, and may be of interest for land use, infrastructure planning, engineering, and hazard mitigation design. The methodologies formulated here could be easily transported to other regions where evaluations of preliminary earthquake-induced landslide potential are desired, especially where data are sparse and/or where regional evaluations have yet to be undertaken.
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    Environmental consequences of adopting source separated sanitation system : first and third world perspectives
    ([Honolulu] : [University of Hawaii at Manoa], [May 2013], 2013-05) Lamichhane, Krishna Mani
    Urine constitutes only about 1% of domestic sewage but contains major fractions of nutrients (90% N, 50% p and 55% K) and chemicals like pharmaceutical residues and estrogens (95%) excreted from the human body. Agricultural food crop yield in many countries is decreasing because of nutrient mining and human undernourishment is 20% or higher in 41 countries. The annual human excretion of nutrients only in urine is more than the average fertilizer application rates in 22 countries. Urine, thus, can serve as a "free" but locally available nutrient source. Urine diverting toilets (UDTs) can be used to separate urine at the source. Coordinated and simultaneous intervention on water sanitation and agriculture could be the most effective and economical means of increasing agricultural yield and reducing water pollution, poverty and hunger in these countries. The human excreted estrogens are recognized endocrine disrupting chemicals (EDCs) and are considered about hundred to thousand times more estrogenic than known EDCs like bisphenol A. The effects can vary from cancer to sex reversals at levels as low as parts per trillion in sensitive organisms. To remove 99% of estrogenicity in discharged waters from source separated urine would require approximately 12 kWh/p-y whereas it would require 23 kWh/p-y to achieve the same removal from bulk wastewater by adding advanced oxidation processes to existing municipal wastewater treatment plants. From an energy standpoint it makes sense to practice source separation and treatment of urine to limit estrogen discharges into the environment. By employing UDT, a typical family in the US could realize a saving of $101/y and a decrease of 100 kg green house gas emissions. A social acceptability study conducted in Hawaii showed that 82% of respondents were willing to use UDTs and more than 60% were willing to pay extra while only 22% knew that such systems existed. With a public education program, it is possible that most people would be willing to adopt UDTs and human waste recycling with incurred societal benefits of reduced water and fertilizer use, reduced greenhouse gas emissions, and collection of EDCs at the source to prevent their entry into waterways.
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    Bore impact upon vertical wall and water-driven, highmass, low-velocity debris impact
    ([Honolulu] : [University of Hawaii at Manoa], [December 2011], 2011-12) Paczkowski, Krystian Wojciech
    This dissertation proposes a method to predict the peak lateral force on a vertical wall from an impacting bore. The formula has been developed based on the analysis of data from large-scale experimental tests on bore impact. The lateral forces are much larger than traditional lateral loads on vertical walls. It is shown, the data indicate that the formula can be used for prototype scale following Froude scaling. Additionally, a computational tsunami bore generation study utilizing the Reynolds Average Navier-Stokes equations is presented. Three bore generating scenarios are reviewed and results are presented, providing guidance on how best to generate bores for further numerical studies. In the latter part of the dissertation, the application of a simple one-dimensional model to obtain impact force magnitude and duration, based on acoustic wave propagation in a flexible projectile, is explored. The focus herein is on in-air impact. Based on small-scale experiments, the applicability of the model to predict actual impact forces is investigated. The tests show that the force and duration are reasonably well represented by the simple model, but they also show how actual impact differs from the ideal model. The one-dimensional model is extended to consider water-driven debris as well. When fluid is used to propel the 1-D model, an estimate of the 'added mass' effect is possible. In this extended model the debris impact force depends on the wave propagation in the two media, and the conditions under which the fluid increases the impact force are discussed. The results indicate that the model provides an accurate estimation of the peak impact force and its duration. For the tested scenario, the maximum impact force does not depend on the total mass of the debris.
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    Sustainability framework for urban transportation modes and exploratory applications
    ([Honolulu] : [University of Hawaii at Manoa], [December 2011], 2011-12) Mitropoulos, Lampros
    Increasing environmental concerns as well as economic and social impacts of transportation in communities necessitate the incorporation of sustainability into the planning process. The common approach for sustainability assessment in transportation considers only personal vehicles or all modes present on a section of a network using aggregate measures of performance. The accelerated development and introduction of vehicles with alternative propulsion systems compel a detailed breakdown of vehicle components and characteristics for the proper understanding of their sustainability performance and impacts over their entire life cycle. This study develops a long-term sustainability-based comprehensive framework for the life cycle assessment of any urban transportation mode. In developing a life cycle sustainability framework (LCSF), the generic structure components of a transportation system and the restrictions that may be faced in its development and implementation are considered. LCSF consists of seven fundamental dimensions that govern transportation systems: (1) Environment; (2) Technology; (3) Energy; (4) Economy, (5) Users and other stakeholders, (6) Legal framework, and (7) Local restrictions. LCSF is used to assess the sustainability performance of 11 vehicles with a variety of propulsion technology. The vehicles are ranked based on their performance per sustainability dimension, and overall sustainability. Gasoline pickup truck (GTP) and gasoline SUV are the most energy demanding vehicles. Hybrid electric are the least energy demanding vehicle per vehicle mile traveled over its life cycle, with 44% lower energy requirements than an internal combustion engine vehicle. Car Share and BRT have the lower energy consumption per passenger mile traveled (PMT). Vehicle-specific results were combined in a tool to perform a sustainability assessment of Atlanta, Chicago and OPTIMUS--a hypothetical metropolitan area with superior transportation sustainability elements. Normalized indicators per metropolitan area are aggregated into a sustainability dimension index (SDI) and an overall sustainability index (OSI). Both SDI and OSI are used to reveal dimension specific and overall sustainability tradeoffs for each alternative when different characteristics, policies, scenarios and assumptions are used. The sustainability LCSF with its proposed indicators provides a workable method both for sustainability assessment in transportation planning and for facilitating policy analysis and decision-making.
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    Membrane fouling study and identifying fouling microorganisms in membrane bioreactors treating municipal wastewater
    ([Honolulu] : [University of Hawaii at Manoa], [December 2011], 2011-12) Huang, Tieshi
    Two bench membrane bioreactors (MBRs), Bench Enviroquip and Bench Ionics, and four pilot MBRs were operated at Honouliui wastewater treatment plant (WWTP) treating municipal wastewater at 10-d, 20-d, 30-d, 40-d mean cell residence time (MCRT), and no sludge wasting conditions for membrane fouling study and identification of fouling microorganisms. Results indicated that bench and pilot MBRs produced high quality effluent water. Higher critical flux was obtained for bench Ionics MBR (39.3 LMH) than for bench Enviroquip MBR (37.4 LMH). No sludge wasting condition showed higher conditioning and steady-state fouling rates. It was found that SMP concentration had no or little effect on membrane fouling process, while carbohydrate EPS concentration appeared to have a significant impact on steady-state fouling rate. Shock loading condition by glucose addition and no anoxic zone condition following the normal 20-d MCRT operation were also evaluated and results did not show any increase of membrane fouling, indicating bench MBRs are capable of handling shock loading and variance in operating schemes without compromising membrane performance. Polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) fingerprinting analysis and 16S rRNA clone library analysis were performed for the bench-scale MBRs. Betaproteobacteria was found to be the dominant bacterial group in MBR mixed liquors (47%). Pseudomonas sp. might involve in membrane fouling process since it was detected extensively in biofilm. The presence of Rhodobacteraceae sp. and Brevundionas sp. might increase membrane fouling too. Laboratory bench MBR with polyvinylidene fluoride (PVDF) and polyvinyl chloride (PVC) ultrafiltration membrane modules were operated to study optimum ultrafiltation membrane cleaning methods. Majority of the membrane resistance at fouled condition was attributed to cake resistance. Vacuum permeation with Clorox® disinfectant + industrial alcohol or propylene glycol solution was found to be the best cleaning method with the highest membrane flux recovery and lowest membrane re-fouling rates. Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and Energy-dispersive X-ray spectroscopy (EDX) analysis indicated less contaminants were observed or detected in ultrafiltration membranes with the optimum cleaning method. DGGE fingerprinting and clone library analyses showed that bacteria responsible for fouling belonged to Betaproteobacteria, Deltaporteobacteria and Bacteroidetes.
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    Riverbank filtration : modeling fate of dissolved organic carbon, transport of Escherichia coli and coupling with aquifer storage to address temporal water scarcity
    ([Honolulu] : [University of Hawaii at Manoa], [August 2012], 2012-08) Sharma, Laxman
    Riverbank filtration (RBF) is an accepted method of treatment for water supply from rivers which markedly improves the source water quality. Pumping water from wells adjacent to water body induces surface water to infiltrate through the aquifer attenuating contaminants present in the source water. This study used field data from an operating RBF system located along the Rhine River in Düsseldorf, Germany, and carried out focused research on the fate of dissolved organic carbon and on transport of E. coli. Furthermore, a novel application of RBF and aquifer storage and recovery (ASR) was considered in a study to address seasonal water scarcity in the Albany region of the Georgia in US. A reactive transport model (PHT3D) was developed to study the fate of dissolved organic carbon incorporating transient boundary conditions. Modeling residence times showed that high floods in the river reduced the travel time to the RBF well to 8 days, while low flows increased it to about 60 days. Aerobic processes with some partial denitrification occured in the aquifer. The temporal changes in the breakthrough of dissolved oxygen were best reproduced when the temperature dependency of the biogeochemical processes was explicitly considered. The results showed that seasonal temperature changes superimposed by changes in residence time strongly affected the extent of redox reactions along the flow path. Microbial transport is modeled in groundwater using the advection-dispersion transport equation adding on the processes of attachment, detachment and inactivation processes. The rates defined by these processes are velocity dependent and cannot be used directly for a transient RBF model. An approach to handle such transient conditions is developed using colloid filtration theory and the concepts of single collector contact efficiency and verified on a benchmark 1-D study. The model is extended to the Rhine River RBF system. The transport of E-coli and coliforms was successfully modeled. The RBF-ASR study showed the viability of obtaining excess river flows through RBF and storing it a deeper aquifer to be recovered later. Geochemical changes were also investigated. The overall study contributes to our understanding of the various processes involved in RBF and subsurface flows.
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    Hydrologic performance analyses, modeling, and design tool development for green roof systems
    ([Honolulu] : [University of Hawaii at Manoa], [August 2014], 2014-08) Li, Yanling
    Green roofs are one of the most recommended best management practices for stormwater management projects. However, their hydrologic performance is difficult to predict or control due to a lack of methodologies for quantitative analyses. The relationship between hydrologic response and its affecting factors, such as green roof configuration, growth media, precipitation properties, antecedent conditions, and evapotranspiration (ET), is highly non-linear. This thesis studied these issues. In this work, more than 100 green roof research papers were investigated and an experimental green roof site with monitoring equipment was constructed. HYDRUS-2D was used for the first time in green roof studies to analyze hydrologic responses of green roofs to ET, irrigation, and precipitation events. Major methodologies developed include: 1) acquiring the growth media hydraulic properties and retention curve parameters; 2) performing dimension simplification to set up simulation geometry; 3) conducting model calibration using growth media water content measurement, precipitation/irrigation monitoring, and ET calculation data; 4) analyzing water content profile for irrigation management; and 5) deriving regression equations for LEED projects. This research also developed a green roof specific model using a system of governing equations. This model resolved the difficulties of general soil physics models in directly connecting hydrologic performance with design parameters, and simulating water storage and extreme dry/wet conditions. It offered rational design-parameter-based criteria for LEED projects. It also discovered the distinctive features of green roof hydrologic response to precipitation characteristics on a broad spectrum through its runoff response curves. Using this model, green roof designs and their hydrologic performance can be iterated to form a powerful design tool for engineers.
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    Removal of bacteria and pharmaceutically active compounds during natural filtration
    ([Honolulu] : [University of Hawaii at Manoa], [May 2014], 2014-05) d Alessio, Matteo
    Natural filtration represents a sustainable technology to enhance the quality of the source water. Slow sand filtration (SSF) and riverbank filtration (RBF) are examples of natural filtration that have been used. SSF is a low-cost water treatment technology often used by small municipalities and households. It can be used to improve the quality of the source water in the aftermath of a natural disaster as well as in underdeveloped countries and rural areas. RBF, on the other hand, can be used as a primary treatment or a pre-treatment of water for municipalities and regional authorities. Similar removal processes, such as filtration, biodegradation, and adsorption, occur during both natural filtration technologies. However, during RBF the additional processes of chemical precipitation, redox reactions and mixing can occur. SSF and RBF showed similar removal efficiency in terms of turbidity (20--90% vs. 70--90%), total coliforms and E. coli (1--3 logs in both filtration technologies). Two SSF units, disposed in parallel or in series, coupled with two post treatment pointof-use (POU) devices (an ultraviolet water treatment, UV unit, or an activated carbon impregnated with silver nanoparticles, AC unit) were used to examine the ability to treat source water with high levels of turbidity (> 20 NTU), high bacterial content (E+6 to E+7 MPN/100 mL of total coliforms and E. coli), and pharmaceutically active compounds (PhACs, at concentration of 50 g/L). Six PhACs, caffeine, carbamazepine, 17- estradiol (E2), estrone (E1), gemfibrozil, and phenazone were selected using a multi-step approach based on: i) occurrence in the environment, ii) toxicity and pharmaceutical class, iii) environmental fate, iv) behavior under different redox conditions, and v) availability of analytical standards and adequate instrumentation. Turbidity removal ranging from 40% to 80% and removal of total coliforms and E. coli greater than 95% was consistently achieved by SSF regardless of the configuration (series vs. parallel) of the units, the hydraulic loading rate, the starting turbidity of the source water and the presence or absence of PhACs. However, the presence of a post treatment unit, such as an UV unit, is desirable to further enhance the quality of the source water, especially in the presence of bacterial loads greater than 106 MPN/100 mL. SSF can also be used to treat water with a high concentration of PhACs such as a wastewater treatment plant spill or a pharmaceutical industry spill. However, the nature and concentrations of the PhACs, the duration of the spill, and the age of the SSF may significantly impact the overall performance of the filtration unit in terms of bacterial removal. Among the selected PhACs, complete removal of caffeine, and partial removal of E2 and E1 (11--92%) were achieved by both SSF units. Adsorption and biodegradation are the main removal mechanisms for the selected PhACs. None to limited (< 10%) removal of carbamazepine, gemfibrozil, and phenazone occurred. Columns and two side-by-side sandbox were used to investigate the role of oxygen (aerobic vs. anoxic), temperature (summer vs. winter), and level of organic matter (TOC = 3, 10, 20 mg/L) on the removal of selected PhACs during simulated RBF. The same PhACs investigated during SSF were also used for the simulated RBF. RBF can be effectively used to remove most of the PhACs present in surface waters. However, the geochemistry of the RBF site is expected to play a key role in their removal. Depending on the compound, removal of PhACs may predominantly occur due to biodegradation, but environmental variables such as oxygen and temperature may enhance or limit biodegradation. Limited and slower removal of selected PhACs may occur during the winter temperature conditions. Limited removal of carbamazepine (< 10%) and gemfibrozil (< 30%) occurred regardless of the different environmental conditions. Among the different PhACs, removal of phenazone occurred only under aerobic conditions, while removal of caffeine was highly impacted by the level of organics as well as by the temperature. The occurrence of air beneath the riverbed can enhance the development of locally present aerobic conditions, that leads to an enhanced removal of redox sensitive PhACs.