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2019

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Articles 1801 - 1830 of 2012

Full-Text Articles in Engineering

A Top-Down Human-Centered Approach To Exoskeleton Design, Thomas Michael Schnieders Jan 2019

A Top-Down Human-Centered Approach To Exoskeleton Design, Thomas Michael Schnieders

Graduate Theses and Dissertations

This dissertation begins, as all good research does, with a thorough review of the literature. The literature is broken into three primary sections covering the early 1960’s when information on exoskeletons was first published up to 1970, then the formative years of 1970 to 2000 where much of the primary technology was developed, and finally 2000 to present where new advancements in battery density, computer processing, and materials leads to more robust and advanced exoskeleton designs. The literature review determines the areas where there is a dearth of research or places needing further examination and lays the groundwork for ...


Volt/Var Control With High Solar Pv Penetration In Distribution Systems And Its Impact On The Transmision Grid, Ankit Singhal Jan 2019

Volt/Var Control With High Solar Pv Penetration In Distribution Systems And Its Impact On The Transmision Grid, Ankit Singhal

Graduate Theses and Dissertations

With increasing distributed energy resources (DERs), both the distribution and transmission power systems are witnessing new challenges and opportunities. Voltage rise and voltage fluctuations are becoming major issues in the distribution network due to high solar PV penetration. Nevertheless, the volt/var control (VCC) capability of solar PV devices (inverter based DERs, in general) opens up various opportunities for both the distribution and transmission systems. In this work, we address the challenges in the distribution network and also explore the potential opportunities for the transmission system that can be provided by VCC capability of DERs in high PV penetration environment ...


Probe Vehicle Performance Measures For Assessing Travel Time Reliability, Kyle Robert Thompson Jan 2019

Probe Vehicle Performance Measures For Assessing Travel Time Reliability, Kyle Robert Thompson

Graduate Theses and Dissertations

Travel time reliability reflects the degree to which the amount of time needed for a trip is predictable. Metrics that quantify travel time reliability are emerging as a fundamental part of assessing the performance of transportation networks. Many states and municipalities are starting to incorporate travel time reliability into their transportation assessments and planning processes. Probe vehicle data is a prevalent data source which can be utilized to compute many of these travel time reliability metrics. This study used probe vehicle data from INRIX to compute, compare, and apply travel time reliability metrics on interstate segments in Iowa. It also ...


Calibration Of Structured Light System Using Unidirectional Fringe Patterns, Vignesh Suresh Jan 2019

Calibration Of Structured Light System Using Unidirectional Fringe Patterns, Vignesh Suresh

Graduate Theses and Dissertations

3D shape measurement has a variety of applications in many areas, such as manufacturing, design, medicine and entertainment. There are many technologies that were successfully implemented in the past decades to measure three dimensional information of an object. The measurement techniques can be broadly classified into contact and non-contact measurement methods. One of the most widely used contact method is Coordinate Measuring Machine (CMM) which dates back to late 1950s. The method by far is one of the most accurate method as it can have sub-micrometer accuracy. But it becomes difficult to use this technique for soft objects as the ...


Design And Development Of Cellulose Based Composites For The Built Environment, Melvin Glenn Veigas Jan 2019

Design And Development Of Cellulose Based Composites For The Built Environment, Melvin Glenn Veigas

Graduate Theses and Dissertations

Cellulose is a versatile material with numerous contemporary applications in textiles, food, and biomaterials. Contemporary research is focused on modifying the structural and thermal properties of cellulose to create novel composites with cellulose nano-crystals, lignocellulosic pulp, and foamed cellulose to name a few. Significant advances have been made in improving the properties of cellulose. Adding aligned cellulose nano-fibers to concrete to improve its mechanical properties or combining with polymers for better durability can lead to new applications specifically in design and construction. These new forms of cellulose through optimization and combination with other materials provide opportunities for reducing material usage ...


Process Generalizations And Rules Of Thumb For Scaling Up Biobased Processes, Mothi Bharath Viswanathan Jan 2019

Process Generalizations And Rules Of Thumb For Scaling Up Biobased Processes, Mothi Bharath Viswanathan

Graduate Theses and Dissertations

The premise of the NSF Engineering Research Center for Biorenewable Chemicals (CBiRC) is that a joint fermentative-catalytic process can be exercised to manufacture commodity chemicals from bio-based carbon (e.g., five and six carbon sugar) at prices that are competitive with existing petro-derived chemicals, and with development costs that are far low. Strong technoeconomic analysis (TEA) capabilities exist commercially in tools such as SuperPro Designer® and Aspen Plus®, both of which provide estimations of capital and operating costs. These tools also require a level of detail that is typically unavailable at early stages of process evaluation. To address early – stage ...


Towards Understanding Material Characteristics Through The Additive Manufacturing Arc, Alden Watts Jan 2019

Towards Understanding Material Characteristics Through The Additive Manufacturing Arc, Alden Watts

Graduate Theses and Dissertations

The directed energy powder feed additive manufacturing (AM) process fabricates components with good quality, accuracy, and efficiency. However, this is a complex process and without careful consideration can lead to discontinuities in the final product such as porosity, cracks, or unfavorable microstructure. These material discontinuities may occur due to the limited understanding of the relationship between AM source materials and the evolution of the composition and microstructure during the deposition process. This makes it vital to study and correlate the composition, morphology, and characteristics of both the source material and of the final printed parts. In this research the properties ...


Analyzing Energy Savings In An Fpga Video Processing System Using Dynamic Partial Reconfiguration, Robert Cole Wernsman Jan 2019

Analyzing Energy Savings In An Fpga Video Processing System Using Dynamic Partial Reconfiguration, Robert Cole Wernsman

Graduate Theses and Dissertations

Dynamic Partial Reconfiguration (DPR) can be a useful tool for maximizing FPGA performance while minimizing power consumption and FPGA size requirements. This work explores the application of the DPR technique in a computer vision application that implements two different edge detection algorithms (FASTX and Sobel). This technique could allow for a similar computer vision system to be realized on a smaller, low-power chipset. Different algorithms can have unique characteristics that yield better performance in certain scenarios; the best algorithm for the current scenario may change during runtime. However, implementing all available algorithms in hardware increases the space and power requirements ...


Data-Driven Analyses Of Future Electric Personal Mobility, Liang Hu Jan 2019

Data-Driven Analyses Of Future Electric Personal Mobility, Liang Hu

Graduate Theses and Dissertations

Personal mobility is moving towards the era of electrification. Adopting electric vehicles (EV) is widely regarded as an effective solution to energy crisis and air pollution. Many automakers have announced their roadmap to electrification in the next 1-2 decades. At the same time, limited electric range and insufficient charging infrastructure are still obstacles to EV large-scale adoption. However, with the emerging technologies of ride-hailing, connected vehicles, and autonomous vehicles, these obstacles are being solved effectively, and the EV market penetration is expected to increase significantly. Among the many kinds of electric mobility, electric taxis and personal battery electric vehicles (BEV ...


Project-Level Instantaneous Emission Modeling From Mobile Sources For Freeway Lane Closure Using Shrp2 Naturalistic Driving Study Data And Microscopic Traffic Simulation, Georges Elias Bou-Saab Jan 2019

Project-Level Instantaneous Emission Modeling From Mobile Sources For Freeway Lane Closure Using Shrp2 Naturalistic Driving Study Data And Microscopic Traffic Simulation, Georges Elias Bou-Saab

Graduate Theses and Dissertations

This dissertation is one of the first studies which used the Second Strategic Highway Research Program (SHRP2) Naturalistic Driving Study (NDS) data to perform modal emission modeling at the project-level. SHRP2 NDS was the largest naturalistic driving study to date conducted in the U.S. which included instrumented vehicles with over 3,000 drivers that were recruited from six states. There is great potential to apply this data in modeling emissions as it will capture differences in driver behavior, roadway geometry, traffic conditions and their impact on emissions. The dissertation had two primary objectives: (1) apply the SHRP2 NDS data ...


Thermal Decomposition Of Chemical Warfare Agent Simulants Diisopropyl Methylphosphonate And Tributyl Phosphate, Patrick Sanderson Jan 2019

Thermal Decomposition Of Chemical Warfare Agent Simulants Diisopropyl Methylphosphonate And Tributyl Phosphate, Patrick Sanderson

Graduate Theses and Dissertations

The pyrolysis of chemical warfare agent simulants, diisopropyl methylphosphonate

(DIMP) and tributyl phosphate (TBP), were studied in a constant volume heated cell

using infrared spectroscopy (9:35 μm to 10:55 μm) over a temperature range of 50 C to

550 C. DIMP began decomposing at 130 C and was undetectable by 280 C. The ex-

pected decomposition products observed were propene, 2-propanol and methylphospho-

nic acid. One unexpected species, methanol, was observed, and isopropyl methylphospho-

nate was not observed. Tributyl phosphate began decomposing as low as 130 C and was

undetectable by 270 C. The pyrolysis of TBP had ...


Data-Driven Approaches For Improving Failure Resilience Of Engineered Systems, Mohammadkazem Sadoughi Jan 2019

Data-Driven Approaches For Improving Failure Resilience Of Engineered Systems, Mohammadkazem Sadoughi

Graduate Theses and Dissertations

Since the 1980s, major industries and government agencies worldwide have faced increasing challenges in ensuring the reliability and resilience of engineered systems. The goal of this dissertation is to create novel probabilistic analysis and design methodologies that enable engineered systems to achieve and sustain near-zero breakdown performance. Specifically, this dissertation is focused on developing new methods for simulation-based design and sensor-based diagnostics and prognostics that can be used to design engineered systems for failure resilience. The research contributions are in the areas of engineering design under uncertainty and post-design fault diagnostics which focuses on applications within wind turbines (energy generation ...


Comparison Of Urans And Des Models For Dynamic Stall Of Naca 0012 At Low Reynolds Number, Anshul Chandel Jan 2019

Comparison Of Urans And Des Models For Dynamic Stall Of Naca 0012 At Low Reynolds Number, Anshul Chandel

Graduate Theses and Dissertations

Designing wings and rotor blades to mitigate the adverse effects of dynamic stall is of current interest. For example, unmanned air vehicles with vertical take-off and landing capability are particularly susceptible to dynamic stall as they operate entirely in the highly unsteady planetary boundary layer. The intense unsteady loads generated as the vehicle undergoes dynamic stall can lead to catastrophic failure as well as fatigue failure. A passive mechanism to mitigate dynamic stall is a desirable alternative to active control as it is simpler, robust, and economical. Innovative wing and rotor blade designs can be developed using numerical simulations and ...


In-Service Evaluation Of Culvert Extensions, Hitesh Chawla Jan 2019

In-Service Evaluation Of Culvert Extensions, Hitesh Chawla

Graduate Theses and Dissertations

Approximately 18% of fatal run-off-road crashes in the US are associated with either a culvert or a ditch. To reduce the risk of such crashes, safety treatments that can be implemented include installation of safety grates or guardrails or extending the culvert outside the clear zone, as mentioned in AASHTO’s Roadside Design Guide. The existing design practices do not indicate when a particular safety treatment should be chosen over others based on the given roadway and traffic conditions. The existing literature has also been quite limited with respect to this problem. To that end, this study aims to determine ...


Controlling The Deterioration Of Harvested Grain/Seed To Improve Food Security, Bernard Darfour Jan 2019

Controlling The Deterioration Of Harvested Grain/Seed To Improve Food Security, Bernard Darfour

Graduate Theses and Dissertations

The agriculture sector is the largest source of employment for Ghanaians and it is dominated by smallholder farmers. The challenges in the agriculture sector are many which include food insecurity. Maize offers a significant source of calories, and accounts for 50% of the total cereal production in Ghana, with the reported postharvest loss (PHL) between 5% and 70%. Improving food security through a reduction of PHL is imperative for meeting current development objectives. Sitophilus zeamais can inflict serious damage to maize in storage leading to about 20% to 50% or more losses within 3 to 6 months. The lack of ...


Incremental And Parallel Algorithms For Dense Subgraph Mining, Apurba Das Jan 2019

Incremental And Parallel Algorithms For Dense Subgraph Mining, Apurba Das

Graduate Theses and Dissertations

The task of maintaining densely connected subgraphs from a continuously evolving graph is important because it solves many practical problems that require constant monitoring over the continuous stream of linked data often represented as a graph. For example, continuous maintenance of a certain group of closely connected nodes can reveal unusual activity over the transaction network, identification, and evolution of active groups in the social network, etc. On the other hand, mining these structures from graph data is often expensive because of the complexity of the computation and the volume of the structures (the number of densely connected structures can ...


Adaptive Hybrid Structures To Enhance Graphene-Based Sensors For Detecting Moisture In Corn Plants, Matthew Davis Jan 2019

Adaptive Hybrid Structures To Enhance Graphene-Based Sensors For Detecting Moisture In Corn Plants, Matthew Davis

Graduate Theses and Dissertations

The utilization of graphene, a two-dimensional structure of carbon atoms, to measure water content in corn plants is presented. Discussed are the structural properties of graphene, fabrication methods, and previous designs by other research groups. This work attempts to design and test a new style of graphene sensor that maintains signal stability while not inhibiting plant growth or health. Specifically, the use of inkjet printing and molds to manufacture the graphene sensor component and the use of a soft polymer for a flexible attachment is examined. Simulations for determining the efficacy of mechanical structures are also analyzed.


Efficient Uncertainty Propagation For Model-Assisted Probability Of Detection And Sensitivity Analysis Via Metamodeling And Multifidelity Methods, Xiaosong Du Jan 2019

Efficient Uncertainty Propagation For Model-Assisted Probability Of Detection And Sensitivity Analysis Via Metamodeling And Multifidelity Methods, Xiaosong Du

Graduate Theses and Dissertations

Physics-based simulation models are important to the decision-making process in the

design of modern engineered systems. The key challenges of using accurate predictive

simulations in this process are (1) time-consuming model evaluations, (2) a large number of

parameters, (3) often complex and highly coupled systems, and (4) conventional modeling

and optimization techniques typically require a large amount of model evaluations. The

research objective of this work is to accelerate the process of UP and optimum design

under uncertainty when the high-delity computational budget is limited. In particular,

the objective is to create and evaluate new metamodeling and multidelity methods that ...


Precast Concrete Bridge Barriers For Accelerated Bridge Construction, Ashley A. Ecklund Jan 2019

Precast Concrete Bridge Barriers For Accelerated Bridge Construction, Ashley A. Ecklund

Graduate Theses and Dissertations

Many transportation organizations have embraced Accelerated Bridge Construction (ABC) to reduce both the traffic impacts and societal costs. One of the most common means to achieve ABC is to utilize prefabricated elements, which are connected together on-site to construct a bridge. ABC will not be effective if the barrier requires cast-in-place construction. The purpose of this report is to present details of a precast barrier and two connection alternatives between the deck and precast barriers. In addition, a new connection between two adjacent prefabricated barriers is presented.

One barrier to deck connection uses inclined reinforcing bars with threaded ends that ...


The Role Of Vec And Local Atomic Environment In Structural Transitions And Stability Of Complex Intermetallic Compounds Through Theoretical And Experimental Study Of Γ-Brasses, Stephanie L. Eveland Jan 2019

The Role Of Vec And Local Atomic Environment In Structural Transitions And Stability Of Complex Intermetallic Compounds Through Theoretical And Experimental Study Of Γ-Brasses, Stephanie L. Eveland

Graduate Theses and Dissertations

The fusion of computational and synthetic techniques provides a powerful investigative arsenal for a systematic consideration of the factors governing the structural makeup and observed physical properties of complex intermetallic compounds such as the non-uniform mixed sites in Mn2+xZn11-x, VEC driven structural transition in Mn5-yAl8-xZnx+y, and atypical atomic decoration of Cu9Al4 γ-brasses. Classic solid state synthetic techniques, self-flux techniques, as well as multiple structural characterization methods such as X-ray diffraction and electron microscopy were employed in the experimental portion of this work. Magnetic susceptibility measurements were utilized when appropriate in the study of the γ- brasses of Mn2 ...


Study Of Combustion Performance Of Al/Ptfe B/Ptfe And B/Al/Ptfe Composites, Liyun Feng Jan 2019

Study Of Combustion Performance Of Al/Ptfe B/Ptfe And B/Al/Ptfe Composites, Liyun Feng

Graduate Theses and Dissertations

Metal particles like aluminum and boron are of great interest as additives to energetic materials due to their high gravimetric and volumetric heat of combustion. However, the ignition temperatures of metals are quite high and their burning rates which depend upon the surface area of the burning metal agglomerates are quite slow. The naturally formed oxide layer on the surface of metal particles can further inhibit their ignition and combustion by limiting fuel/oxidizer transport. The boron oxide layer on boron particles is of particular interest due to the strong diffusion barrier formed by its presence. However, the ignition temperature ...


Deep Learning For Monitoring Cyber-Physical Systems, Tryambak Gangopadhyay Jan 2019

Deep Learning For Monitoring Cyber-Physical Systems, Tryambak Gangopadhyay

Graduate Theses and Dissertations

Different cyber-physical systems involving sequential data require accurate frameworks for predicting the state of the system leading to effective monitoring. If the framework is explanatory, the insights provided by the explanations can improve scientific understanding of the system. Detecting the transition to an impending instability is important to initiate effective control in a combustion system. Building robust frameworks is important in this context.

As one of the early applications of characterizing instability in a combustion system using Deep Neural Networks, we train our proposed deep convolutional neural network (CNN) model on sequential image frames extracted from hi-speed flame videos by ...


Simulation Of Soil-To-Tool Interaction Using Discrete Element Method (Dem) And Multibody Dynamics (Mbd) Coupling, Sadaf Ghorbani Jan 2019

Simulation Of Soil-To-Tool Interaction Using Discrete Element Method (Dem) And Multibody Dynamics (Mbd) Coupling, Sadaf Ghorbani

Graduate Theses and Dissertations

Multi-physics simulation of soil-to-tool interaction using a coupled Discrete Element Method (DEM) and Multibody dynamics (MBD) techniques can support the design of off-road equipment. Quantitative prediction of the soil reaction forces on the equipment is essential to provide a reliable simulation-based design. DEM is a computational method for simulating the dynamic behavior of granular materials. In the coupling interface, DEM gives a high fidelity prediction of the forces for soil-to-soil and soil-to-tool interaction, which can be used in the MBD simulation workflow. Two laboratory tests were used to capture the bulk material behavior: the angle of repose test for calibration ...


A Locally-Implicit Lax-Wendroff Discontinuous Galerkin Scheme With Limiters That Guarantees Moment-Realizability For Quadrature-Based Moment Closures, Christine Wiersma Jan 2019

A Locally-Implicit Lax-Wendroff Discontinuous Galerkin Scheme With Limiters That Guarantees Moment-Realizability For Quadrature-Based Moment Closures, Christine Wiersma

Graduate Theses and Dissertations

A polydisperse multiphase flow is one in which one of the thermodynamic phases can be considered discrete while the other is assumed to be continuous. Examples include sprays and bubbly flows. Such flows can be modeled by kinetic models that describe the evolution of a probability density function (PDF) in phase space. Moments of this PDF describe physical observable quantities such as the mass, momentum, and energy in

the flow. From a computational perspective, kinetic models are expensive to solve since they require the resolution of a very high-dimensional phase space. In many polydisperse multiphase flow applications, the phase space ...


Construction And Performance Of Chemically And Mechanically Stabilized Granular Road Test Sections, Yijun Wu Jan 2019

Construction And Performance Of Chemically And Mechanically Stabilized Granular Road Test Sections, Yijun Wu

Graduate Theses and Dissertations

Granular-surfaced roadways in Iowa rural area frequently experience damage and degradation from the effect of rainfall, flooding, seasonal freeze-thaw cycles, heavy agricultural machinery and steadily increasing traffic loads. Rutting, potholes and frost boil problems appeared usually and leading these granular roads to unpassable. As a result, many counties have to close damaged roads for repairs and spend significant portions of their budgets on maintenance and rehabilitation of granular roads. Several stabilization methods for granular roads were examined for improving the performance and minimizing damages in Iowa by the previous completed Phase II Iowa Highway Research Board Project TR-664 “Low-Cost Rural ...


Airline Fleet Planning And Utilization Hours Comparison Studies, Daniel Zhou Jan 2019

Airline Fleet Planning And Utilization Hours Comparison Studies, Daniel Zhou

Graduate Theses and Dissertations

After the latest mechanical malfunction accidents involving Allegiant and Southwest Airlines, a special interest was taken to investigate whether low-cost carriers (LCC) are taking an overly aggressive stance in regards to the utilization of aircraft within their respective fleets. Based on summary reports obtained from incident logs generated by the FAA (Federal Aviation Administration) and NTSB (National Transportation Safety Board), it was observed that Allegiant Airlines was almost three and a half times as likely to encounter a mid-air breakdown as legacy carriers are. On the economic front, the fallout that Southwest Airlines has faced from the Flight 1380 incident ...


A Path For Microsecond Structural Health Monitoring For High-Rate Nonstationary Time-Varying Systems, Jonathan Hong Jan 2019

A Path For Microsecond Structural Health Monitoring For High-Rate Nonstationary Time-Varying Systems, Jonathan Hong

Graduate Theses and Dissertations

In this dissertation, a new area of research identified as high-rate state estimation is established along with its associated research challenges, and a path for a solution is provided. High-rate dynamic systems are defined as systems being exposed to highly dynamic environments that are comprised of high-rate and high-amplitude events (greater than 100 g for a duration under 100 ms). Engineering systems experiencing high-rate dynamic events, including airbag, debris detection, and active blast protection systems, could benefit from real-time observability for enhanced performance. This task of high-rate state estimation is particularly challenging for real-time applications, where the rate of an ...


Animated Rendering Of Cardiac Model Simulations, Xin Huang Jan 2019

Animated Rendering Of Cardiac Model Simulations, Xin Huang

Graduate Theses and Dissertations

Heart disease has been the leading cause of death both in the world and the United States

in the past decade. Computational cardiac modeling and simulation, especially patient-specific

cardiac modeling has been recognized as one of the best ways to improve diagnosis of heart

disease by providing insights in individual disease characteristics that cannot be obtained by

other means. However presenting the results of cardiac simulations to cardiologists in an

interactive manner can considerably improve the utility of cardiac models in understanding

the heart function. In this work, we have developed virtual reality and animated volume

rendering techniques to render ...


Use Of Soft Computing And Numerical Analysis In Design, Analysis And Management Of Pavement Systems, Orhan Kaya Jan 2019

Use Of Soft Computing And Numerical Analysis In Design, Analysis And Management Of Pavement Systems, Orhan Kaya

Graduate Theses and Dissertations

There are a number of components of pavement engineering, including pavement management, pavement analysis and design, and pavement materials. Historically, the field of pavement management has been interested in monitoring post-construction condition, timing of preventive maintenance and rehabilitation treatments, and economic analysis of alternatives. On the other hand, the field of pavement analysis and design has dealt with optimizing pavement structure; with optimum structure, a pavement system is expected to survive during its service life for given traffic and climate conditions. The performance of pavement materials has been improved to achieve the long-lasting and lower-maintenance pavement systems. A data-driven comprehensive ...


Embedding Runtime Verification Post-Deployment For Real-Time Health Management Of Safety-Critical Systems, Brian Christopher Schwinkendorf Kempa Jan 2019

Embedding Runtime Verification Post-Deployment For Real-Time Health Management Of Safety-Critical Systems, Brian Christopher Schwinkendorf Kempa

Graduate Theses and Dissertations

As cyber-physical systems increase in both complexity and criticality, formal methods have gained traction for design-time verification of safety properties.

A lightweight formal method, runtime verification (RV), embeds checks necessary for safety-critical system health management; however, these techniques have been slow to appear in practice despite repeated calls by both industry and academia to leverage them.

Additionally, the state-of-the-art in RV lacks a best practice approach when a deployed system requires increased flexibility due to a change in mission, or in response to an emergent condition not accounted for at design time.

Human-robot interaction necessitates stringent safety guarantees to protect ...