Engineering Commons^™

Understanding The Marginal Utilities Of Commute Time, Work Time, Travel Cost, And Income Using Stated Preferences Surveys, Niranjan Poudel

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

In transportation economics, measuring the willingness to pay (WTP) for a reduction in travel time–the monetary value of travel time savings (VTTS) –plays an important role in understanding the social benefits of various transportation projects. These monetary appraisals (WTP, VTTS) are better understood either through expensive daily activity-travel-expenditure diaries or using discrete choice experiments (DCEs). This study made use of data collected from two different stated preference surveys – a type of DCEs - (one from Portland, Oregon, US, and one from all over the US) to understand the marginal utilities of work, commute, income, and travel cost. The marginal …

Active Stability Monitoring And Stability Control Of Dc Microgrids Using Incremental Continuous Injection, Rohail Hassan

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Electrified transportation and integration of renewable energy in the electric power grid requires the use of power electronic converters for integrating different forms of power; from ac to dc, dc to ac, dc to dc, etc. Recent trend towards electrifying automobiles, aircraft and ships, and increasing penetration of renewable energy has increased the required power levels and number of the power electronics converters connected together in a dc microgrid system. Stable operation of these interfacing converters for all operating conditions has been a topic of renewed interest in the last couple of decades. Traditionally, dc microgrids have been designed conservatively …

Control Of Series Connected Battery Powered Modules, Joshua K. Wooten

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Batteries are a very common type of power source used for all sorts of applications. However, these batteries do not last forever. The purpose of this thesis is to explain and implement a strategy which allows batteries to have a second life; to be able to be re-charged and re-used for another set period of time once they no longer meet a system’s requirements. The preferable way to do this is to make each cell have the same state of charge (SOC) which will lead to a longer lasting battery pack. These batteries will be hooked up to a battery …

Exact And Approximate Relaxation Techniques For Computational Guidance, Sheril Avikkal Kunhippurayil

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The focus of this dissertation is in the development and application of relaxation techniques that enable efficient and real-time solution of complex computational guidance problems. Relaxations transform a non-convex constraint into a convex constraint and provides proof that the optimal solutions to the relaxed problem are optimal for the original problem. Unique contributions of this work include: 1) a relaxation technique for solving fixed final time problems between fixed points, 2) a performance analysis on the application of computational guidance for the Mars Ascent Vehicle, and 3) establishment of sufficient conditions for non-singularity of optimal control for problems on a …

Analysis Of Large Embankment Dam In Case Of Rapid Drawdown And Earthquake Aftershock, Pothikul Vivithkeyoonvong

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Dams and reservoirs are important as a source of freshwater as well as for regulating flooding and producing hydroelectricity. The same as with any other manmade structure, dams need to monitored and maintained to prevent disastrous failure.

One of the events that can reduce the stability of an embankment dam is rapid drawdown. Rapid drawdown is when the water level decreases at such a rapid rate that the dam material(s) cannot drain and adjust to the change in time. Without the buttressing effect of the water, the upstream slope of the dam becomes less stable. Another threat to dam stability …

3d-Printed Morphing Wings For Controlling Yaw On Flying-Wing Aircraft, Benjamin C. Moulton

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The flaps on an airplane wing are used to control the aircraft during flight. These flaps traditionally have at most three articulation or hinge points. Recent studies have shown improved flap efficiency using a conformal flap, which deforms following a curved shape. Much of aircraft improvement comes through increasing its efficiency during flight. This efficiency is generally improved by decreasing the drag force on the aircraft. A potential solution to decrease drag is to remove additional lifting surfaces, such as the horizontal and vertical stabilizer ubiquitous on general aviation aircraft. These additional lifting surfaces are used to trim and control …

Attitude And Reflection Parameter Estimation Of Resident Space Objects Using Ground-Based Photometry, Arun J. Bernard

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

There are currently thousands of objects orbiting Earth, and this number is only going to increase. Larger number of satellites will require that operators have a greater knowledge of the state their assets. Electro-optical telescopes are currently being used to observe and track many of these objects. When using these telescopes to take images of satellites, they often appear as dots in the image. Depending on the surface properties of the satellite, and its orientation at a given time, the dots in the image can appear brighter or dimmer. Photometry measurements are a quantification of how bright the object appears. …

Safety In Numbers: Models Of Pedestrian And Bicycle Crash Frequency And Severity At Signalized Intersections In Utah Using Innovative Measure Of Exposure, Ahadul Islam

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Recent trends indicate a dramatic increase in both the number and share of pedestrian and bicyclist injuries and fatalities nationally and in many states. This study aimed at understanding (geometric, traffic, operational, and other) factors associated with pedestrian and bicycle safety and also to assist in the prioritization and selection of countermeasures to improve pedestrian and bicycle safety at signalized intersections. Several negative binomial models were estimated to investigate factors affecting pedestrian and bicycle crash frequency. The models suggested several characteristics of the road network, land use, built environment, and neighborhood sociodemographics were significantly associated with more (or fewer) pedestrian …

An Analysis Of Electromagnetic Flowmeters: A Numerical Study, Kade J. Beck

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

As water scarcity increases, improved water management through better water measurement is of critical global significance. Today, the most common way to measure water in drinking water and wastewater systems is to use an electromagnetic (magnetic) flowmeter. A magnetic flowmeter has many components, and their accuracy can be compromised if not installed or calibrated correctly. The purpose of the present study was threefold. Each of the three components has been named to help the reader understand the context of the study without getting lost in the details.

The Idealist. Using mathematical programs, the spacing of two types of magnetic flowmeter …

Embracing Low-Power Systems With Improvement In Security And Energy-Efficiency, Pramesh Pandey

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

As the economies around the world are aligning more towards usage of computing systems, the global energy demand for computing is increasing rapidly. Additionally, the boom in AI based applications and services has already invited the pervasion of specialized computing hardware architectures for AI (accelerators). A big chunk of research in the industry and academia is being focused on providing energy efficiency to all kinds of power hungry computing architectures. This dissertation adds to these efforts.

Aggressive voltage underscaling of chips is one the effective low power paradigms of providing energy efficiency. This dissertation identifies and deals with the reliability …

Analysis And Design Of 3-Phase Unfolding Based Ac-Dc Battery Chargers, Rees R. Hatch

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

This thesis presents the analysis and design of high-efficiency battery chargers for heavy duty EV applications. The rise in popularity of the electric vehicles (EVs) due to their increased efficiency over conventional internal combustion engines, has driven the need for more battery charging infrastructure. Furthermore, heavy duty vehicles are also being converted to electric to fill needs such as public transportation via bus fleets as well as cargo delivery via semi-trucks. Such heavy duty vehicles require more energy than personal transportation vehicles and thus require larger battery packs. To charge heavy duty battery packs in the same amount of time …

From Attitude To Satisfaction: Introducing The Travel Mode Choice Cycle, Jonas De Vos, Patrick A. Singleton, Tommy Gärling

Civil and Environmental Engineering Faculty Publications

Many studies analysing the relationship between attitudes and travel behaviour have found that travel attitudes have an important impact on travel mode choice. More recently, studies focusing on how people experience travel have shown that travel satisfaction is influenced by the chosen travel mode. The desire and intention of using a travel mode – which can be considered as important predictors of mode choice – have, however, received limited attention. Furthermore, existing studies mostly have a narrow scope and lack integration of the above constructs. In this paper, we introduce the travel mode choice cycle (TMCC), a comprehensive model aiming …

Hydrolearn: Improving Students’ Conceptual Understanding And Technical Skills In A Civil Engineering Senior Design Course, Melissa Ann Gallagher, Jenny Byrd, Emad Habib, David G. Tarboton, Clinton S. Wilson

Civil and Environmental Engineering Faculty Publications

Engineering graduates need a deep understanding of key concepts in addition to technical skills to be successful in the workforce. However, traditional methods of instruction (e.g., lecture) do not foster deep conceptual understanding and make it challenging for students to learn the technical skills, (e.g., professional modeling software), that they need to know. This study builds on prior work to assess engineering students’ conceptual and procedural knowledge. The results provide an insight into how the use of authentic online learning modules influence engineering students’ conceptual knowledge and procedural skills. We designed online active learning modules to support and deepen undergraduate …

An Open Source Cyberinfrastructure For Collecting, Processing, Storing And Accessing High Temporal Resolution Residential Water Use Data, Camilo J. Bastidas Pacheco, Joseph C. Brewer, Jeffery S. Horsburgh, Juan Caraballo

Publications

Collecting and managing high temporal resolution residential water use data is challenging due to cost and technical requirements associated with the volume and velocity of data collected. We developed an open-source, modular, generalized architecture called Cyberinfrastructure for Intelligent Water Supply (CIWS) to automate the process from data collection to analysis and presentation of high temporal residential water use data. A prototype implementation was built using existing open-source technologies, including smart meters, databases, and services. Two case studies were selected to test functionalities of CIWS, including push and pull data models within single family and multi-unit residential contexts, respectively. CIWS was …

Practicing Self-Regulation Of Cognition And Motivation During Problem Solving In Engineering And Mathematics, Oenardi Lawanto

Funded Research Records

No abstract provided.

Experimental And Numerical Analysis Of The Hydraulic Jump Stilling Basin And The Downstream Scour Depth, L. J. Miranda, R. Sánchez

International Junior Researcher and Engineer Workshop on Hydraulic Structures

This paper presents a study of a tridimensional low-head hydraulic jump stilling basin by using both physical and numerical models. Laboratory tests up to 15 hours in duration were carried out in a 1.9 m wide and 14 m long flume. Four gates produced a jet with a submerged hydraulic jump in a positive-step stilling basin, after which scour developed in a nearly uniform sand bed. Acoustic Doppler Velocimeter, piezometers and image processing were used to collect the hydrodynamic data, and Reynolds Averaged Navier-Stokes simulations developed in OpenFOAM were tested for validation purposes. Then, the study focused on (1) the …

Three-Dimensional Characterization Of Laboratory Scour Holes Around Bridge Piers, Ana Margarida Bento, Teresa Viseu, João Pedro Pêgo, Lúcia Couto

International Junior Researcher and Engineer Workshop on Hydraulic Structures

The presence of a bridge foundation leads to the formation of a scour hole, from which entrainment and transport of sediments are controlled by the turbulent structures therein developed. Hence, once formed, these scour holes interfere significantly with the scouring process in several ways, for instance, by modifying the incoming flow patterns. Therefore, a three-dimensional survey of the scour hole and the characterization of the deposition features is essential for prevention and safety control purposes. To investigate this, scouring experiments around two oblong bridge piers were performed in a tilting flume of the Portuguese National Laboratory of Civil Engineering (LNEC), …

Scour Downstream Of Log-Frame Structures In The Presence Of Rigid Vegetation, Deep Roy, Simone Pagliara

International Junior Researcher and Engineer Workshop on Hydraulic Structures

Recently, various low-head environment friendly structures have been used to control the sediment transport and preserve river navigability. Among these structures, double winged log-frames are effective for concentrating the flow by decreasing channel width. Moreover, they create scour holes which can be used by fishes as resting spots. Usually, log-frames are placed in mountainous curved channels where there is natural growth of various types of in-stream vegetation in the downstream stilling basin of the structure which influences scour geometry and depth. Therefore, the current study aims to analyze the impact of rigid woody vegetation, placed downstream of double winged log-frames, …

Estimation Of The Efficiency Of Hydraulic Pumps, A. Martin-Candilejo, D. Santillán, L. Garrote

International Junior Researcher and Engineer Workshop on Hydraulic Structures

A sustainable design of water supply systems needs to account operational costs. When pumping is required, the energy consumed by the pumps plays a major part in the operational costs, and the efficiency of the pumps can greatly affect the energy expenses. How to properly estimate the value of pump efficiency is hence of great importance. The aim of this study is to study in depth the efficiency of hydraulic pumps, in relation with the other design variables (flow rate, pumping head, power, etc.). For that, 400 hydraulic pumps were analysed. A strong relationship between the flow rate and the …

Streamflow Duration Curves: Focus On Low Flows, E. Carcano, M. Betasolo

International Junior Researcher and Engineer Workshop on Hydraulic Structures

Flow duration curves (FDCs) express the link between a selected streamflow and the percentage in time such value is exceeded. The curves provide a graphical insight into hydrological regimes, though, the absence of time-series data is a significant shortcoming. Conversely to what happens with hygrograms, flows in FDCs are represented without regard of sequence of occurrence. This paper explores FDCs of 19 catchments for which, at least, 10 years of daily discharges are available. FDCs can be built for any temporal scale (i.e. daily, weekly, monthly). In this study daily discharges have been adopted because daily scale better represents the …

Flow Distribution In Slotted Pipe Bottom Outlets, Felipe Azevedo Paulo, Eder Daniel Teixeira

International Junior Researcher and Engineer Workshop on Hydraulic Structures

Reservoir sedimentation is a major threat to dam operation. It can reduce water storage capacity, clog water intakes, and damage turbine components. Flushing operations by bottom outlets are a mitigation measure that allows removing sediment deposited near the dam. Unfortunately, the effect of such structures is localized if no water level draw down takes place; therefore, investigations of new designs that improve sediment removal have emerged recently. In this work, we present our current results on the investigation of the slotted pipe bottom outlet obtained through numerical modeling. The flow patterns were characterized for different water levels, showing that discharges …

Calibration Of A Hydraulic Model For Seasonal Flooding In A Lowland River With Natural Diversions And Bathymetric Uncertainty, For Dam Downstream Impact Assessment, Getachew E. Mamo, Davide Motta, Martin Crapper

International Junior Researcher and Engineer Workshop on Hydraulic Structures

A method is developed to generate bank-full river main channel geometry, to complement an open-source Digital Elevation Model (DEM) and produce a calibrated hydraulic model reproducing the extent of historically observed overbank flooding. This approach relies on limited surveyed cross section and flow rate information and is potentially suitable for projects in developing countries where the availability of measured data is limited. The method presented is applied to the case of the seasonal flooding of the Baro River in the Gambela floodplain in Ethiopia, modelled with a two-dimensional hydraulic model. The simulated flooding extent for the 1990 wet season is …

Particle Image Velocimetry (Piv) Investigation Of Local Scour Around Emergent And Submerged Circular Cylinders, P. Williams, R. Balachandar, V. Roussinova, R. Barron

International Junior Researcher and Engineer Workshop on Hydraulic Structures

Analysis of the velocity field surrounding a circular cylinder under equilibrium of local scour has been restricted due to practical limitations of commonly used measurement techniques. This investigation summarizes select cases in the literature which have attempted to circumvent such limitations and presents flow field measurements using Particle Image Velocimetry (PIV). Scour tests were conducted in a horizontal flume fitted with a sediment recess containing erodible bed material. Tests were conducted with both emergent and submerged circular cylinders for a period of 24 hours, after which equilibrium was achieved and planar PIV measurements were obtained in the streamwise-vertical symmetry plane. …

Comparison Of Pressure Distribution In 2d And 3d Jet-Driven Scour Processes, Simone Pagliara, Deep Roy

International Junior Researcher and Engineer Workshop on Hydraulic Structures

Water jets impacting on a non-cohesive granular bed cause a dynamic pressure distribution on the surface of the scour hole. Such distribution greatly differs from the hydrostatic one, especially in proximity of the impact zone, where the kinetic energy of the jet is dissipates due to the shear stresses acting on the scour surface. Here, the excess of shear stress causes the erosion of the bed material and can lead to the failure of hydraulic structures. Therefore, a detailed analysis of the forces acting on the scour surface is fundamental to understand the erosion mechanisms. Experimental tests were conducted under …

Modelling Velocity Profiles Of Aerated Flows Down Grassed Spillways, H. Cui, S. Felder, M. Kramer

International Junior Researcher and Engineer Workshop on Hydraulic Structures

The ecological and environmental benefits of grassed spillways present a green solution to the construction of low head conveyance structures. On a grassed spillway, the aggregate of the grass canopy and root structure may alter flow resistance, velocity distribution and other flow properties. While subcritical flows in vegetated open channels have been extensively researched, only little is known about flow properties in supercritical high-velocity flows, which are typically characterized by self-aeration. The current study explores the application of a velocity superposition to supercritical aerated flows on a spillway with artificial grass. Velocity measurements were conducted with a Pitot tube and …

A Critical Analysis Of Jet-Induced Scour Formulas, J. Di Nardi, M. Palermo, S. Pagliara

International Junior Researcher and Engineer Workshop on Hydraulic Structures

Many studies investigate erosive processes occurring in non-cohesive granular materials downstream of grade-control structures, dam spillways, headcuts, and other hydraulic structures. Because of the complexity of the scour mechanism, the analysis of the scour phenomenon caused by plunging jets is generally conducted by using physical models and particularly for specific structure geometries. In this regard, many researchers proposed empirical approaches to estimate the main scour lengths, but their contributions are limited to tested conditions and cannot be generalized. This lack of generality has been (partially) overcome by other, more recent, approaches, that are either semitheoretical or fully theoretical. Previous works …

Numerical Simulation Of Fish Passage Over A Weir, Linus Kaminski, C. Thorenz, R. Weichert

International Junior Researcher and Engineer Workshop on Hydraulic Structures

Downstream migration over weir structures has been a mostly neglected element of ecological continuity in the last decades. The guidelines currently applied in Germany to prevent damage to fish do not sufficiently consider the conditions present at weirs. To improve knowledge of the risks of fish passage over a weir due to physical strike, pressure changes and shear stress, a numerical method using the three-dimensional computational fluid dynamics package OpenFOAM® was developed to simulate fish passage over a weir by tracking passively transported particles. In this study, the method is tested on an overshot and an undershot weir and the …

Effect Of Boundary-Layer Development On The Water-Surface Fluctuations Of Supercritical Flow Below A Sluice Gate, Ryugen Satoh, M. Takahashi, I. Ohtsu

International Junior Researcher and Engineer Workshop on Hydraulic Structures

Hydraulic structures with a sluice gate are commonly used for control of the flow. In supercritical flow below a sluice gate, an accurate estimation of the water depth and boundary layer thickness is important for the hydraulic design of a horizontal apron. The relation between water-surface fluctuations and boundary-layer development has not been clarified. The aim of this paper is to experimentally demonstrate the effect of boundary-layer development on water-surface fluctuations of supercritical flow below a sluice gate. It is shown that water surface begins to fluctuate slightly upstream of the critical point. The water-surface fluctuations and turbulence intensities downstream …

Cfd Simulation Of Supercritical Flow In Narrow Channels Including Sediment Bypass Tunnels, Subhojit Kadia, Elena Pummer, Nils RüTher

International Junior Researcher and Engineer Workshop on Hydraulic Structures

Secondary currents, turbulence characteristics and bed shear stress distribution are the crucial parameters for specifying sediment transport. Hence, to understand the sediment transport in sediment bypass tunnels (SBTs), we performed computational fluid dynamics (CFD) simulation of supercritical flow in a narrow straight channel. The results of the steady state simulation (Froude number ≈ 1.8) were compared with experimental results. The commonly used two-equations linear eddy-viscosity models are limited to isotropic turbulence closure and hence could not replicate the desired secondary currents. Therefore, the LRR Reynolds Stress Model was used, and predicted the flow features and the secondary currents (three kinds …

Probability Of Woody Debris Passage At Rock Weirs, Kathryn A. Margetts, B. M. Crookston

International Junior Researcher and Engineer Workshop on Hydraulic Structures

Often, large woody debris (LWD) at hydraulic structures is considered hazardous from a performance and public safety perspective. However, the sustainable management of rivers requires the consideration of ecological impacts of LWD such as cover for aquatics and the natural movement of LWD through a catchment. Therefore, this study explores the interaction of natural (nonuniform) LWD with rock weirs through field observations in the Blacksmith Fork River in Utah, USA and laboratory testing at the Utah Water Research Laboratory. The passage probability of individual LWD at rock weirs is observed and tested in an effort to describe the balance between …