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Full-Text Articles in Engineering
A New Passive Surface Water Flux Meter For Simultaneous Measurement Of Contaminant And Water Fluxes In Streams And Rivers, Stephen A. Sassman
A New Passive Surface Water Flux Meter For Simultaneous Measurement Of Contaminant And Water Fluxes In Streams And Rivers, Stephen A. Sassman
Open Access Dissertations
A passive surface water flux meter (PSFM) for measurement of contaminant concentration/flux in rivers and streams is described and tested. The novel PSFM design was developed for portability and ease of adaptability for a variety of contaminant classes. Although previous designs have been evaluated under constant flow conditions, the PSFM has never been used for measurement of pesticides or hormones and this is the first time that it has been tested under transient flow. Discharge through the PSFM is assessed by measuring miscible displacement of alcohol tracers from granular activated carbon (GAC). The tracer retardation factors (R) measured by miscible …
Impact Of Anthropogenic Activities On Hydro-Climatological Variables, Kuk Hyun Ahn
Impact Of Anthropogenic Activities On Hydro-Climatological Variables, Kuk Hyun Ahn
Open Access Dissertations
The natural environment has been significantly affected by anthropogenic activities. Between 1700s and 2000s, agricultural land area had quintupled and the extent of natural vegetation was globally reduced by half. Furthermore many scientists argue that the recent rise in CO2 levels in the atmosphere is mainly due to anthropogenic activities. Anthropogenic activities may also play a crucial role in the change of the hydro-climatologic variables. In this study, impact of anthropogenic activities on two representative hydro-climatologic variables, temperature and streamflow, is investigated. The variations in temperature occur over larger spatial and time scale, and hence the United States is adopted …
Integrating Pro-Environmental Behavior With Transportation Network Modeling: User And System Level Strategies, Implementation, And Evaluation, Husain M. Abdul Aziz
Integrating Pro-Environmental Behavior With Transportation Network Modeling: User And System Level Strategies, Implementation, And Evaluation, Husain M. Abdul Aziz
Open Access Dissertations
Personal transport is a leading contributor to fossil fuel consumption and greenhouse (GHG) emissions in the U.S. The U.S. Energy Information Administration (EIA) reports that light-duty vehicles (LDV) are responsible for 61\% of all transportation related energy consumption in 2012, which is equivalent to 8.4 million barrels of oil (fossil fuel) per day. The carbon content in fossil fuels is the primary source of GHG emissions that links to the challenge associated with climate change. Evidently, it is high time to develop actionable and innovative strategies to reduce fuel consumption and GHG emissions from the road transportation networks. This dissertation …
Nano-Modification For High Performance Cement Composites With Cellulose Nanocrystals And Carbon Nanotubes, Yizheng Cao
Nano-Modification For High Performance Cement Composites With Cellulose Nanocrystals And Carbon Nanotubes, Yizheng Cao
Open Access Dissertations
One of the new engineering frontiers is the exploration of infrastructure materials with novel combinations of properties that break traditional paradigms. The goal of this study is to utilize two different nano-fibers, cellulose nanocrystals (CNCs) and carbon nanotubes (CNTs) to modify the nanoscale structures of cement composites and thereby improve the performance at the macro-level. This study also evaluates the mechanism behind the modification, since fiber bridging, the most common reinforcing mechanism for fiber-reinforced composites, cannot be simply applied because CNCs are too short to bridge cracks in cement composites. ^ The mechanical tests show an increase in the flexural …
Irrigation With Treated Wastewater: Potential And Limitations, Anne Dare
Irrigation With Treated Wastewater: Potential And Limitations, Anne Dare
Open Access Dissertations
As the world population increases and resources become more coveted, water emerges as a key component to global food security. The Middle East and North Africa (MENA) is among the driest regions in the world: containing just one percent of the world's freshwater resources. An increasing population creates greater quantities of wastewater and demands greater quantities of food, so an obvious connection arises. However logical wastewater reuse may be for bridging the irrigation supply-demand gap in this arid region, significant limitations prevent widespread adoption. The overall goal of this research is to take a holistic view of the limitations facing …
A Nonlinear Interface Formulation For Frictional Contact, Layla K Amaireh
A Nonlinear Interface Formulation For Frictional Contact, Layla K Amaireh
Open Access Dissertations
Finite element simulations of contact problems often involve modeling the interaction of multiple bodies across a non-confirming interface. Non-Confirming Meshes (NCM) are typically associated with large sliding or adaptive refinement on one side of the interface to capture localized nonlinear behavior due to large deformations, damage and inelasticity. The use of NCMs, however, presents a number of numerical issues; the main challenge with such discretizations is to ensure compatibility of the kinematic and traction fields along the non-conforming interface. ^ The Enriched Discontinuous Galerkin Approach (EDGA) (Haikal and Hjelmstad,2010)addresses this challenge by implementing a local enrichment along with an interface …
A Stochastic Multi-Criteria Assessment Of Security Of Transportation Assets, Michelle Sophie Dojutrek
A Stochastic Multi-Criteria Assessment Of Security Of Transportation Assets, Michelle Sophie Dojutrek
Open Access Dissertations
Transportation project evaluation and prioritization use traditional performance measures including travel time, safety, user costs, economic efficiency, and environmental quality. The project impacts in terms of enhancing the infrastructure resilience or mitigating the consequences of infrastructure damage in the event of disaster occurrence are rarely considered in project evaluation. This dissertation presents a methodology to address this issue so that in evaluating and prioritizing investments, infrastructure with low security can receive the attention they deserve. Secondly, the methodology can be used for evaluating and prioritizing candidate investments dedicated specifically to security enhancement. In defining security as a function of threat …
Experimental Database, Analysis And Design Of Noncompact And Slender Concrete-Filled Steel Tube (Cft) Members, Zhichao Lai
Experimental Database, Analysis And Design Of Noncompact And Slender Concrete-Filled Steel Tube (Cft) Members, Zhichao Lai
Open Access Dissertations
Concrete-filled steel tube beam-columns are categorized as compact, noncompact or slender depending on the governing tube slenderness ratio. AISC 360-10 specifies the provisions for designing noncompact and slender rectangular and circular CFT members under axial compression, flexure, and combined axial and flexural loading. This research presents the development and evaluation of these design provisions. Available experimental databases of CFT members are reviewed, and a new experimental database of tests conducted on noncompact and slender CFT members is compiled. Detailed 3D finite element method (FEM) models are developed for noncompact and slender CFT members, and benchmarked using experimental results. The AISC …
Effects Of Web Reinforcement Discontinuities On The Seismic Response Of Structural Walls, Ying Wang
Effects Of Web Reinforcement Discontinuities On The Seismic Response Of Structural Walls, Ying Wang
Open Access Dissertations
Field evidence was interpreted to suggest that discontinuities in the longitudinal web reinforcement caused severe damage in structural walls during strong ground motion. To test this hypothesis, six small-scale reinforced concrete structural walls were tested under lateral displacement reversals. Test variables included the presence of web longitudinal reinforcement discontinuities and number of loading cycles. The test results indicated that unit tensile strains in longitudinal reinforcing bars in boundary elements were approximately 50% higher in structural walls with web longitudinal reinforcement cutoffs relative to walls without reinforcement cutoffs. Higher unit tensile strains caused an increase in permanent strain accumulation, increasing the …
Scour In Regions Of Flow Separation With Free-Surface Effects, John Frederick Newton
Scour In Regions Of Flow Separation With Free-Surface Effects, John Frederick Newton
Open Access Dissertations
Downstream of essentially all overflow and drop structures two distinct flow regimes are possible, one associated with a plunging flow, the other dominated by a flow that rides along the surface. Predicting the flow regime is important because diving-jet scouring rates are substantially faster than surface flow scouring rates, and diving-jet scour holes form nearer to the structure. A bi-stable region exists in which either flow is possible with the same upstream and downstream flow conditions. Bi-stable regime boundaries were delineated for a wide variety of fixed bed structures, based on both new experiments and reanalysis of others' experiments with …
Concession Analysis For Highway Infrastructure Projects Financed As Public-Private Partnerships, Tanaphat Jeerangsuwan
Concession Analysis For Highway Infrastructure Projects Financed As Public-Private Partnerships, Tanaphat Jeerangsuwan
Open Access Dissertations
Public funds allocated to the improvement and maintenance of highway infrastructure have reached the limits due to a rapid rate of socioeconomic growth and deterioration in infrastructure system performance. A public-private partnership (PPP) concessions a contractual and project financing mechanism that helps public authorities lessen the impact of their limited financial resources. In this project financing scheme, a public authority enters into a partnership with a private concessionaire for the purpose of developing a specific infrastructure facility. In return, the concessionaire receives the right to operate for a specified period of time. This creates strong potential for the delivery of …