Engineering Commons^™

Moving Bed Biofilm Reactors: Evaluation Of Geometry, Attachment Surface Material And Biofilm Populations On The Uptake Of Ammonia And Synthetic Organic Contaminants In Wastewater., Patrick D. Mclee

Civil Engineering ETDs

Plastic biofilm carriers are used in biological wastewater treatment to encourage the attachment and retention of microorganisms that metabolize pollutants. The following research was conducted to better understand how different characteristics of the biofilm carrier affect the treatment performance of the attached biofilms in moving bed bioreactors. Lab scale reactors were used in this study to grow nitrifying biofilms in reactors with contrasting and controlled conditions. The effect of surface geometry on nitrification performance was evaluated by testing commercially available moving bed bioreactor media that contrast in physical design, and by varying operational parameters. Additionally, mature biofilm from a similar …

Quantifying The Effect Of Construction Site Factors On Concrete Quality, Costs And Production Rates, Jorge L. Santamaria

Civil Engineering ETDs

Factors affecting concrete can be categorized as structured factors or unstructured factors. The first group of factors consists of those related to the production process of concrete including water-cement ratio, properties of raw materials and mix proportions. Unstructured factors or construction site factors are related to labor skills and local conditions during the construction process of a project. Concrete compressive strength as a quality metric, costs and production rates may be affected significantly by such factors while performing concrete operations at the jobsite. Several prior studies have investigated the effect of structured factors on concrete. However literature is limited regarding …

Development Of Design Equations For Drilled Shafts In Granular Dense Soils Using Dem Simulations, Sadia Faiza

Civil Engineering ETDs

Drilled shafts have proven to be cost-effective, excellent performing, deep foundation systems where large loads and lateral resistance are major factors. The available design methods that are recommended by FHWA (2010) for drilled shafts are mostly empirical and are developed based on generalized data which sometimes can be conservative for a particular soil. The main objective of this study is to develop a design methodology for estimating the side resistance of an axially loaded drilled shaft based on the current and the unique properties of the soil. The objective was met through using the discrete element method (DEM) to investigate …

Characterization And Modeling Of Asphalt Concrete For Dynamic Properties And Performances, A S M A. Rahman

Civil Engineering ETDs

The recently developed mechanistic-empirical pavement design guide (MEPDG, also known as Pavement M-E design method) uses the nationally calibrated, binder viscosity-based dynamic modulus predictive model for the design and analysis of asphalt pavements. In this study, this model is assessed for its appropriateness for asphalt-aggregate mixtures typically used in New Mexico. In essence, this study investigates the predictability issue of complex modulus of New Mexico mixes. A total of 54 Superpave mixes with different aggregate gradations, air voids, and binder grades were collected from the mixing plants and from the pavement construction sites. The loose asphalt mixtures were then compacted, …

Viscoelastic Behavior Of Carbon Fiber Reinforced Polymer Composites Incorporating Nanomaterials, Amy R. Garner

Civil Engineering ETDs

Carbon fiber reinforced polymer (CFRP) composites are increasingly being used in a variety of industries such as aerospace and infrastructure. This investigation experimentally examines the effect of incorporating alumina nanoparticles (ANPs), non-functionalized multi-walled carbon nanotubes (NF-MWCNTs), and functionalized multi-walled carbon nanotubes (F-MWCNTs) on the off-axis stiffness and stress-relaxation of carbon fiber reinforced polymer (CFRP) composites. Epoxy- nanocomposites incorporating 0.0, 1.0, 2.0, and 3.0 wt.% ANPs; 0.0 0.5, 1.0, and 1.5 wt. % NF-MWCNTs; 0.0 0.5, 1.0, and 1.5 wt. % F-MWCNTs of the total weight of epoxy are examined. Off-axis tension stiffness and stress-relaxation tests were performed on CFRP coupons …

Applying Modern Technology In The Preservation Of Historic Concrete Picnic Tables, Michele M. Anderson

Civil Engineering ETDs

Preserving historical concrete structures recognizes the work and skills of past generations and allows the communities surrounding these pieces of history the opportunity to enjoy the character and purpose of their construction. Restoration of concrete picnic tables, constructed in the 1930s by the Civilian Conservation Corps, required researching materials and methods of construction during the original construction period. Eight decades of environmental and weather cycles did not decay the historic structures. Acts of vandalism destroyed the purpose of the tables and benches. Restoration of the historic picnic tables required extensive literature review for the materials and methods used during the …

Hydrogeochemical Investigation Of Recharge Pathways To Intermediate And Regional Groundwater In Cañon De Valle And Technical Area 16, Los Alamos National Laboratory, Brendan W. Brady

Civil Engineering ETDs

In aquifers consisting of fractured or porous igneous rocks, as well as conglomerate and sandstone products of volcanic formations, silicate minerals actively dissolve and precipitate (Eby, 2004; Eriksson, 1985; Drever, 1982). Dissolution of hydrated volcanic glass is also known to influence the character of groundwater to which it is exposed (White et al., 1980). Hydrochemical evolution, within saturated zones of volcanic formations, is modeled here as a means to resolve the sources feeding a perched groundwater zone. By observation of solute mass balances in groundwater, together with rock chemistry, this study characterizes the chemical weathering processes active along recharge pathways …

State-Based Peridynamic Particle Method, Siavash Nikravesh Kazeroni

Civil Engineering ETDs

In this study, a novel discrete Peridynamics framework called the “State-Based Peridynamic Particle Model (SPPM)” is introduced. In this approach, a solid body is simulated by neither solving differential equations nor integral equations; instead, the simulation is accomplished by directly solving discrete systems of equations using finite summations. SPPM is formulated for a random distribution of particles, hence, it can be considered as a meshfree method. The assumptions of continuity and homogeneity are not necessary for this approach. The SPPM is a generalization of the “State-Based Peridynamic Lattice Model (SPLM)”. In the SPLM formulation, for sake of simplicity and computational …

Comprehensive Evaluation Of Rutting Performance Of Asphalt Concrete Mixtures, Ivan Syed

Civil Engineering ETDs

Rutting is the permanent deformation along the wheel paths of an asphalt pavement caused by repeated traffic loading. It is considered as one of the primary distresses of asphalt pavements. Recently, Hamburg Wheel Tracking Device (HWTD) has shown to measure the rutting performance of an asphalt mixture in the laboratory. In this study, this device has been used to measure rutting of asphalt concrete (AC) and relate them with the mixture’s dynamic modulus. To this end, the rut deformation of AC mixtures were modeled in this study using a semi-empirical |E*|-based rut predictive model based on the HWTD …

Characterization Of Asphalt Healing And Incorporation In A Fatigue Damage Model, Umme A. Mannan

Civil Engineering ETDs

Healing is defined as the restoration of the material property during the rest period after damage. The healing property of the asphalt binder is opposite to fatigue damage, which occurs due to repeated traffic loading. On the other hand, healing occurs in the rest period between loading. Most of the existing methods for characterizing the fatigue damage and healing of asphalt are empirical in nature and do not consider the mechanism of healing. Although the asphalt concrete is a mixture of asphalt binder, fines and aggregates, most of the healing occurs in the asphalt binder. Therefore, it is important to …

Rejection Of Low Molecular Weight Neutral Organics By Reverse Osmosis Membranes For Potable Reuse, Lauren N. Breitner

Civil Engineering ETDs

Factors such as increasing population, urbanization, and climate change have made the management of water resources a challenge for many municipalities. Water reuse, especially direct potable reuse (DPR) of treated wastewater, is increasingly seen as a potential source of water for communities facing water shortages. Due to improvements in analytical capabilities as well as concerns regarding toxicology of contaminants of emerging concern (CECs), the need for investigating the removal of CECs has become crucial for further DPR considerations. Reverse osmosis (RO) has been demonstrated to remove many CECs. Many studies, however, have investigated the removal of well-known CECs, often with …

A Numerical Investigation Of The Implications Of Altered Channel-Floodplain Connectivity On Hydrodynamic Flood Wave Processes, Colin F. Byrne

Civil Engineering ETDs

With severely altered rivers throughout the developed world, hydrodynamic processes and floodplain connectivity have changed drastically. The research presented here focuses on quantification of two hydrodynamic processes: flood wave attenuation and channel-floodplain fluxes. Objectives of the three research chapters were to (1) evaluate how the ecosystem service of flood wave attenuation has changed with the implementation of river engineering practices as well as contemporary river restoration efforts, (2) describe the sensitivities of flood wave attenuation to contemporary and altered conditions, and (3) characterize channel-floodplain connectivity through lateral flux metrics. All chapter objectives were met using high-resolution, two-dimensional hydrodynamic modeling techniques …

Characterization Of Unknown Bridge Foundations, Saman Rashidyan

Civil Engineering ETDs

The National Bridge Inventory (NBI) recognized 86,133 bridges in the United States have no foundation data on record in 2003. It is evident that an unknown percentage of the 86,133 bridges identified by NBI with missing foundation data could also be highly vulnerable to scouring induced by water flow coupled with erodible soils. Conventional excavation, coring and boring excavations to identify unknown bridge foundation depths and types are deemed to be expensive, destructive, and limited in their application to the unknown foundation problem. Many surface and borehole nondestructive testing (NDT) technologies have been developed for this purpose. Three economical proven …

A New Fiber Reinforced Polymer Composite For Infrastructure Applications Using Recycled Carbon Fibers, Mojgan Maadandar

Civil Engineering ETDs

Abstract

Carbon fiber reinforced polymer (CFRP) composites have been attractive materials for many civil and mechanical applications. However, the high cost of carbon fibers has hindered its wide spread in many civil and structural applications. Furthermore, CFRP composites have been mostly disposed of in landfills after their end of service life, creating environmental concerns and potential release of toxic byproducts. A significant interest in recycling composites has appeared in the last decade for obtaining recycled carbon fiber. A process based on wet chemical degradation and thermal treatments of FRP composites showed the ability to produce recycled carbon fibers with 99% …

Viscoelastic Effects In Carbon Fiber Reinforced Polymer Strain Energy Deployable Composite Tape Springs, Elisa C. Borowski

Civil Engineering ETDs

Strain energy deployable composite structures are of great importance to the aerospace community due to their light weight, high stiffness, impressive flexibility, compact stowage configuration, and ability to self-deploy. These attributes make composite deployable hinges ideal for aerospace applications that can benefit from decreased payload and decreased structural complexity through a reduction in deployment parts. However, successful application of these deployable structures requires an in-depth understanding of their mechanical behavior throughout stowage and deployment processes. Upon release from a high strain stowage configuration, high deployment accelerations caused by a great amount of stored strain energy could potentially damage the structure …

Mechanical Characterization Of Polymer Concrete With Nanomaterials, Alaeddin Douba

Civil Engineering ETDs

Nanomaterials are defined by those whose characteristic length scale lies within the nanometer scale. Their extreme dimension achieves extraordinary mechanical properties superior to other micro and macro additives. The introduction of nanotechnology to Civil Engineering utilizes low volume inclusions of nanomaterials to alter the properties of conventionally used bulk materials. Polymer Concrete (PC) where epoxy polymer binders replace cement binders, has become a common repair material among many other application and often can be considered an alternative to Portland cement concrete (PCC). PC is often used in bridge deck overlays, manholes, machine foundations and repairs. Its diverse chemical composition and …

Comprehensive Silica Removal With Ferric Compounds For Industrial Wastewater Reuse, Ehren D. Baca

Civil Engineering ETDs

Cooling towers, integrated circuit (IC) manufacture and reverse osmosis (RO) generate copious amounts of wastewater high in colloidal and reactive silica inhibiting on-site or synergistic reuse. Silica present in cooling water can reach solubility limits via evaporation and form impervious scale on heat transfer surfaces that decreases efficiency. When water is treated by RO operating at high rejection, silica forms difficult-to-remove scale on the membrane feed side in the form of glassy patches and communities of aggregate particles, inhibiting aspirations for zero liquid discharge. Current methods for silica scale mitigation include abundant dosing with chemical antiscalents or complex operating schemes. …

Pavement Surface Distress Detection, Assessment, And Modeling Using Geospatial Techniques, Su Zhang

Civil Engineering ETDs

Roadway pavement surface distress information is essential for effective pavement asset management, and subsequently, transportation agencies at all levels dedicate a large amount of time and money to routinely collect data on pavement surface distress conditions as the core of their asset management programs. These data are used by these agencies to make maintenance and repair decisions. Current methods for pavement surface distress evaluation are time-consuming and expensive. Geospatial technologies provide new methods for evaluating pavement surface distress condition that can supplement or substitute for currently-adopted evaluation methods. However, few previous studies have explored the utility of geospatial technologies for …

Cost-Effective Monitoring Of Railroad Bridge Performance, Jose Alberto Gomez Romero Salazar

Civil Engineering ETDs

The railroad network carries 40 % of the freight in the US. Railroad bridges are the most critical part of the network and they need to be properly maintained for safety of operations. Railroad managers need to inspect the bridges in order to assess their structural condition. Railroad managers are interested in measuring displacements under train crossing events to prioritize their bridge management and safety decisions. However, bridge displacements are difficult to collect in the field, because they require a fixed reference from where to measure. Accelerations can be used to estimate dynamic displacements but to this date, the pseudo-static …

Hyporheic Nitrate Uptake And Stoichiometric Limitations: Mesocosm Experiments Along A River Continuum., Vanessa A. Garayburu Caruso

Civil Engineering ETDs

Nutrient uptake in streams and rivers is controlled by complex transport dynamics and biogeochemical interactions, which together regulate nutrient export from watersheds. Decoupling the relative contributions of transport and biogeochemical processes to nutrient uptake at the watershed scale has been challenging due to the spatial and temporal heterogeneity of physicochemical properties. Furthermore, logistical constraints have resulted in solute-specific analyses, primarily concentrated in headwater streams, that disregard the role of stoichiometry in controlling biological uptake. We used experimental mesocosm (column experiments) along the Jemez River-Rio Grande continuum (1^st-8^th stream order) to isolate spatial differences in biological nitrate uptake. …

Reactor Design And Operation Variables To Improve Mixed Algal Biomass Productivity And Solids Separation: An Examination Of Operation Parameters, Density, And Settleability, Derek Jan Wichhart

Civil Engineering ETDs

Algae have been identified as a source of renewable, clean energy, with much research being devoted to identifying high energy yield algae, energy extraction methods, and reactor design with mono-cultures of algae, but little research has been done on reactor design and operational conditions with mixed cultures of algae to improve productivity and solids separation. The objective of this study was to determine if the settling characteristics of mixed algal cultures can be enriched or improved through manipulation of reactor design characteristics by incorporating cyclic settling or floating phases into operation, timing of light/dark cycles, and/or control of the solids …

Integrated Framework For Wildfire Risk Mitigation Planning At The Wildland/Urban Interface, Elmira Kalhor

Civil Engineering ETDs

Past suppression-based wildfire management practices have increased the frequency and intensity of wildfires. Advocates for the re-introduction of natural wildfire regimes must also prioritize wildfire damage protection, especially for vulnerable communities located near forests. Areas where urban and forest lands interdigitate are called the Wildland Urban Interfaces (WUIs). In the United States, the area of the WUIs is increasing, making more people vulnerable to wildfires. By responding to four research objectives, this dissertation proposed and tested an integrated framework for wildfire risk mitigation decision making at WUIs. Decision makers who could benefit from the results of this dissertation include WUI …

Use Of Chemical And Isotopic Identifiers To Characterize Ground Water Contamination Near Two Uranium Mill Sites, Central Nm, Mitchell T. Schatz

Civil Engineering ETDs

Chemical and isotopic signatures were used to discriminate between anthropogenic ground water and naturally occurring constituents. The U-234/U-238 activity ratio (AR) was determined in 34 samples from several aquifers underlying two former uranium mills near Milan, NM. Disposal of uranium ore waste into unlined tailings resulted in ground water contamination in the Lower San Mateo Creek Basin area. Ground water contamination from uranium mills have impacted the local ground water for residents down-gradient from the mills.

Previous studies that used uranium isotopes identified activity ratios of mill-derived uranium were near the secular equilibrium of 1, and those from natural ground …

Study Of Vibration For Detection And Recognition Of Concealed Machinery Within Buildings, Sushil Ghimire

Civil Engineering ETDs

Recently international concern about nuclear proliferation has rapidly increased. Some governmental agencies have an interest in remotely detecting and recognizing concealed machinery within buildings to detect any anomalous activity occurring inside the building.

The vibration studies of the roof and the exhaust structures of an existing utility building, the Ford Utility Center at the University of New Mexico and a simplified laboratory structure representing an industrial building, called the doghouse are presented in this thesis. The vibration studies presented allow the reader to understand to what extent it is possible to identify machines concealed within a building.

To identify machines …

Practical Considerations In Determining Timber Pile Depth Using The Sonic Echo Method, Ali F. Jwary

Civil Engineering ETDs

The Federal Highway Administration indicates that about 85,000 bridges in the United States have no original contract documents with information about the type, depth, geometry and material of their foundations (FHWA, 2010). Furthermore, the National Bridge Inventory (NBI) provides information about 86,133 bridges nationwide that are rated as scour critical because of unknown foundation condition. In New Mexico, there are more than 281 bridges with unknown foundations, which are owned by the New Mexico Department of Transportation; 71 of these are timber bridges. These data indicate a serious problem that needs decisive action to assess the unknown bridge foundation characteristics …