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Articles 2731 - 2760 of 6329

Full-Text Articles in Engineering

A Probabilistic Model Of Benefit-Cost Analysis For Highway Construction Projects, Yue He Apr 2015

A Probabilistic Model Of Benefit-Cost Analysis For Highway Construction Projects, Yue He

Open Access Theses

Deterministic method occupies the predominant position in economic analysis. However, by using a single value to estimate the project value, deterministic method would hide the risk under it. Analysts may make incorrect judgments by looking at a value without knowing the likelihood of its occurrence and the consequences of its occurrence. A probabilistic model was developed in this study to address this problem. It was found in this study that the traffic flows on Indiana highways follow logistic distributions rather than normal distributions as generally believed. The application of the probabilistic model was illustrated through a case study. The results …

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Diagnosis Of Systematic Defects Based On Design-For-Manufacturability Guidelines, Dhawal Krishana Gupta Apr 2015

Diagnosis Of Systematic Defects Based On Design-For-Manufacturability Guidelines, Dhawal Krishana Gupta

Open Access Theses

All products in the Very-Large-Scale-Integrated-Circuit (VLSIC) industry go through three major stages of production - Design, Verification and Manufacturing. Unfortunately, neither of these stages are truly perfect, hence we need two more sub-stages of manufacturing, namely Testing and Defect Diagnosis to prevent imperfections in ICs. Testing is used to generate test vectors to validate the functionality of the Device-under-Test (DUT), and Defect Diagnosis is the process of identifying the root-cause of a failing chip, i.e., the location and nature of defect. Systematic defects are unintended structural and material changes at specific locations with a higher probability of failure due to …

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Kernel And Bulk Density Changes Due To Moisture Content, Mechanical Damage, And Insect Damage, Danping Guo Apr 2015

Kernel And Bulk Density Changes Due To Moisture Content, Mechanical Damage, And Insect Damage, Danping Guo

Open Access Theses

Corn (Zea Mays), is one of the major grain crops in the world and moisture content, mechanical damage and insect damage are three factors that affect its quality. The primary goal of this thesis was to investigate the effects of moisture content, mechanical damage and insect damage on kernel and bulk density of corn. The study was conducted using two corn hybrids, Pioneer 1352 and Pioneer 1221, that were grown on Purdue Agronomy Farm for Research and Education (ACRE), manually picked and shelled. In Objective 1, the effect of three different moisture conditioning processes (drying from harvest moisture, …

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Trajectory Generation For Lane-Change Maneuver Of Autonomous Vehicles, Ashesh Goswami Apr 2015

Trajectory Generation For Lane-Change Maneuver Of Autonomous Vehicles, Ashesh Goswami

Open Access Theses

Lane-change maneuver is one of the most thoroughly investigated automatic driving operations that can be used by an autonomous self-driving vehicle as a primitive for performing more complex operations like merging, entering/exiting highways or overtaking another vehicle. This thesis focuses on two coherent problems that are associated with the trajectory generation for lane-change maneuvers of autonomous vehicles in a highway scenario: (i) an effective velocity estimation of neighboring vehicles under different road scenarios involving linear and curvilinear motion of the vehicles, and (ii) trajectory generation based on the estimated velocities of neighboring vehicles for safe operation of self-driving cars during …

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Comprehensively Simulating The Mixed-Mode Progressive Delamination In Composite Laminates, Zhenyuan Gao Apr 2015

Comprehensively Simulating The Mixed-Mode Progressive Delamination In Composite Laminates, Zhenyuan Gao

Open Access Theses

Delamination, or interlaminar debonding, is a commonly observed failure mechanism in composite laminates. It is of great significance to comprehensively simulate the mixed-mode progressive delamination in composite structures because by doing this, people can save a lot of effort in evaluating the safe load which a composite structure can endure.^ The objective of this thesis is to develop a numerical approach to simulating double-cantilever beam (DCB) and mixed-mode bending (MMB) tests and also of specifying/validating various cohesive models. A finite element framework, which consists of properly selecting time integration scheme (explicit dynamic), viscosity, load rate and mass scaling, is developed …

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Characterization Of Wake Effects And Loading Status Of Wind Turbine Arrays Under Different Inflow Conditions, Xiangyu Gao Apr 2015

Characterization Of Wake Effects And Loading Status Of Wind Turbine Arrays Under Different Inflow Conditions, Xiangyu Gao

Open Access Theses

The objective of the present work is to improve the accuracy of Actuator Line Modeling (ALM) in predicting the unsteady aerodynamic loadings on turbine blades and turbine wake by assessing different methods used to determine the relative velocity between the rotating blades and wind. ALM is incorporated into a Large Eddy Simulation (LES) solver in OpenFOAM (Open Field Operations and Manipulations). The aerodynamic loadings are validated by experiment results from National Renewable Energy Laboratory (NREL). Turbine wakes are validated by predictions of large eddy simulation using exact 3D blade geometries from a two-blade NREL Phase VI turbine. Three different relative …

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Air Traffic Management Under Uncertain Weather Impact, Le Gao Apr 2015

Air Traffic Management Under Uncertain Weather Impact, Le Gao

Open Access Theses

Air traffic management under uncertain weather impact is a difficult problem. In this thesis, by dividing the whole air traffic systems into small cells, a new method using database to integrate weather and flight data is proposed. An algorithm has been developed to project weather data onto cells. This research also uses a predictive view to find ights which are affected by severe weather. And a prototype detour algorithm is applied on those flights based on the status information of each cell.

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Drop Volume Modulation Via Modulated Contact Angle In Inkject Systems, Aaron Fulton Apr 2015

Drop Volume Modulation Via Modulated Contact Angle In Inkject Systems, Aaron Fulton

Open Access Theses

To date, there are limited options in the ability to adjust feature sizes when inkjet printing. The reduction of nozzle size has been the primary method by which smaller features are created. Prior attempts to reduce feature sizes have all come with some restriction or another, as they are only accessible on certain systems, are difficult to manufacture, tune, cause clogging, etc. Few attempts to create droplets of smaller radii than that of the nozzle from which they are produced have been successful. Additionally, many fluids cannot be jetted whatsoever. Existing methods pertain largely to piezoelectric inkjet printing and time …

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Improving Product Design Phase For Engineer To Order (Eto) Product With Knowledge Base Engineering (Kbe), Hanhdung Thi Dinh Apr 2015

Improving Product Design Phase For Engineer To Order (Eto) Product With Knowledge Base Engineering (Kbe), Hanhdung Thi Dinh

Open Access Theses

In industry currently Computer Aided Design (CAD) is an important tool for the modification, analysis, or optimization of the 3D virtual environment that replicates the physical product. CAD software is an efficient and reliable tool. However, as globalization increases customer demands, this process needs to be faster and more efficient to accommodate changing product design situations, especially for Engineer-to- Order (ETO) products. ^ The traditional method of product design process is to operate CAD software without argumentation. Design engineers create CAD prototypes and drawings based on available knowledge and information which comes from engineering experts, company standards, industrial practices as …

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Considerations For Nondestructive Evaluation Of Discontinuous Fiber Composites Using Dynamic Analysis, Rebecca A. Cutting Apr 2015

Considerations For Nondestructive Evaluation Of Discontinuous Fiber Composites Using Dynamic Analysis, Rebecca A. Cutting

Open Access Theses

Knowledge of the composite microstructure is vital to predicting performance of the structural member. However, depending on the manufacturing process, the microstructure of the part may be unknown and not predictable with simulation software. A few non-destructive evaluation techniques have been adjusted to predict fiber orientation of composites, including CT scans and thermography, but none have proven acceptable on a large scale with the amount of fidelity required. This research investigated the use of dynamic analysis as a non-destructive evaluation technique to predict fiber orientation of discontinuous fiber compression molded parts. While the method is currently unable to predict individual …

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Characterization And Evaluation Of Head Impact Sensors And Varsity Football Helmets, Brian R. Cummiskey Apr 2015

Characterization And Evaluation Of Head Impact Sensors And Varsity Football Helmets, Brian R. Cummiskey

Open Access Theses

An increased understanding of the effects of brain injury in recent years has led to greater attention being given to the topic. A desire to investigate the causal agents of these injuries in athletes has led to the development and use of several devices that track head impacts as well as improving helmet technology to protect players from said impacts. In order to determine which devices are able to best measure head impacts, a Hybrid III headform was used to quantify the accuracy for translational and angular accelerations. Testing was performed by means of administering impacts to a helmet on …

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Conflict And Error Management: A Case In The Furniture Industry, Glenn Candranegara Apr 2015

Conflict And Error Management: A Case In The Furniture Industry, Glenn Candranegara

Open Access Theses

The purpose of this study is to investigate and provide tools for the furniture industry, for detecting and preventing damage from propagating errors. Many of the errors cascading in a furniture manufacturing facility are typically detected only after the original process that causes the error had already caused errors. Previous research has developed and validated theoretical methods, such as CEPD, to prevent and detect errors and conflicts. This thesis is the first effort to implement the logic of CEPD in the furniture industry. There are four relevant measures that are analyzed and improved in this thesis; they are preventability, reliability, …

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Modeling And Analysis Of A Resonant Nanosystem, Scott L. Calvert Apr 2015

Modeling And Analysis Of A Resonant Nanosystem, Scott L. Calvert

Open Access Theses

The majority of investigations into nanoelectromechanical resonators focus on a single area of the resonator's function. This focus varies from the development of a model for a beam's vibration, to the modeling of electrostatic forces, to a qualitative explanation of experimentally-obtained currents. Despite these efforts, there remains a gap between these works, and the level of sophistication needed to truly design nanoresonant systems for efficient commercial use. Towards this end, a comprehensive system model for both a nanobeam resonator and its related experimental setup is proposed. Furthermore, a simulation arrangement is suggested as a method for facilitating the study of …

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Numerical Characterization Of Convective Heat Transfer Of Low-Rise Buildings, Ranchi Chen Apr 2015

Numerical Characterization Of Convective Heat Transfer Of Low-Rise Buildings, Ranchi Chen

Open Access Theses

The convective heat transfer coefficient (CHTC) is an important parameter to evaluate the efficiency of building-integrated photovoltaic/Thermal (PV/T) system and the energy exchange within the turbulent atmospheric boundary layer. Reynolds-average Navier-Stokes approach has been frequently used to predict the CHTC at the surface of low rise roof but incapable of predicting transient behavior of separation, reattachment and recirculation both on the windward and leeward surface. However, Large Eddy Simulation approach (LES) could provide accurate flow field and temperature field around the low rise building. ^ The current study uses Large Eddy Simulation with Smagorinsky-Lily model and the Shear Stress Transport …

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Performance Analysis Of Vortex Based Mixers For Confined Flows, Timo Buschhagen Apr 2015

Performance Analysis Of Vortex Based Mixers For Confined Flows, Timo Buschhagen

Open Access Theses

The hybrid rocket is still sparsely employed within major space or defense projects due to their relatively poor combustion efficiency and low fuel grain regression rate. Although hybrid rockets can claim advantages in safety, environmental and performance aspects against established solid and liquid propellant systems, the boundary layer combustion process and the diffusion based mixing within a hybrid rocket grain port leaves the core flow unmixed and limits the system performance. One principle used to enhance the mixing of gaseous flows is to induce streamwise vorticity. The counter-rotating vortex pair (CVP) mixer utilizes this principle and introduces two vortices into …

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High Density Collagen Fibril Constructs With Tunable Mechano-Biology In Acellular And Cellular Configurations, Kevin Blum Apr 2015

High Density Collagen Fibril Constructs With Tunable Mechano-Biology In Acellular And Cellular Configurations, Kevin Blum

Open Access Theses

Collagen has long been used as a material for tissue engineering due to its prevalence in the extracellular matrix of connective tissues. However, traditional collagen materials utilizing atelocollagen and acid solubilized telocollagen have lacked the mechanical integrity and collagen fibril density found in the in vivo state. Here, we utilize collagen oligomers and confined compression to forcibly remove a portion of the fluid phase component. Materials were created with controlled, substantially increased material properties, including order of magnitude increases in collagen fibril density, elastic modulus, compressive modulus,and resistance to proteolytic degradation. The technique was found to be amenable to cell …

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Effect Of Electrode Geometry On High Energy Spark Discharges In Air, Mounia Belmouss Apr 2015

Effect Of Electrode Geometry On High Energy Spark Discharges In Air, Mounia Belmouss

Open Access Theses

The government, aerospace, and transportation industries are deeply invested in developing new technologies to improve the performance and maneuverability of current and future aircraft while reducing aerodynamic noise and environmental impact. One of the key pathways to meet these goals is through aerodynamic flow control, which can involve suppressing or inducing separation, transition and management of turbulence in boundary layers, increasing the lift and reducing the drag of airfoils, and gas mixing to control fluctuating forces and aerodynamic noise [1]. In this dissertation, the complex flow field following a spark discharge is studied for a range of geometries and discharge …

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Characterization Of Vectorization Strategies For Recursive Algorithms, Shruthi Balakrishna Apr 2015

Characterization Of Vectorization Strategies For Recursive Algorithms, Shruthi Balakrishna

Open Access Theses

A successful architectural trend in parallelism is the emphasis on data parallelism with SIMD hardware. Since SIMD extensions on commodity processors tend to require relatively little extra hardware, executing a SIMD instruction is essentially free from a power perspective, making vector computation an attractive target for parallelism. SIMD instructions are designed to accelerate the performance of applications such as motion video, real-time physics and graphics. Such applications perform repetitive operations on large arrays of numbers. While the key idea is to parallelize significant portions of data that get operated by several sequential instructions into a single instruction, not every application …

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Low Income, Supermarket Accessibility, And The Transportation Network: A Multimodal Analysis Identifying Areas Of Poor Accessibility And Intervention Strategies In Indianapolis, Indiana, Andrea Leigh Bailey Apr 2015

Low Income, Supermarket Accessibility, And The Transportation Network: A Multimodal Analysis Identifying Areas Of Poor Accessibility And Intervention Strategies In Indianapolis, Indiana, Andrea Leigh Bailey

Open Access Theses

The United States Department of Agriculture (USDA) Economic Research Service estimates that 23.5 million people live in food deserts, over half of which are considered low-income residents. Accurately defining a food desert is crucial as the designated areas can benefit from grant opportunities and funding priority. To qualify as an urban food desert, the USDA requires that at least 500 residents or one-third of the population live outside a one-mile buffer from a supermarket as well as have a median income of less than 80% of the area average or a poverty rate of greater than 20%. Approaches in the …

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Asymptotic Modelling Of A Thermopiezoelastic Anisotropic Smart Plate, Yufei Long Apr 2015

Asymptotic Modelling Of A Thermopiezoelastic Anisotropic Smart Plate, Yufei Long

Open Access Theses

Motivated by the requirement of modelling for space flexible reflectors as well as other applications of plate structures in engineering, a general anisotropic laminated thin plate model and a monoclinic Reissner-Mindlin plate model with thermal deformation, two-way coupled piezoelectric effect and pyroelectric effect is constructed using the variational asymptotic method, without any ad hoc assumptions. Total potential energy contains strain energy, electric potential energy and energy caused by temperature change. Three-dimensional strain field is built based on the concept of warping function and decomposition of the rotation tensor. The feature of small thickness and large in-plane dimension of plate structure …

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The Effects Of An Electric Field On The Sintering Of Ceramics, Kara E. Luitjohan Apr 2015

The Effects Of An Electric Field On The Sintering Of Ceramics, Kara E. Luitjohan

Open Access Theses

Sintering is a method used to condense a solid powder material into a single solid mass allowing for the production of metal or ceramic parts. Different sintering techniques involve the manipulation of different processing variables. To fully exploit the processing variables, how they affect the sintering process must be fully understood. One such processing variable is an applied electric field, utilized in spark plasma sintering and flash sintering. Both techniques allow for densification to occur at lower temperatures and in shorter times when compared to other sintering techniques. Though various theories exist in literature for how the electric field affects …

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Quantifying Moisture Transport In Cementitious Materials Using Neutron Radiography, Catherine L. Lucero Apr 2015

Quantifying Moisture Transport In Cementitious Materials Using Neutron Radiography, Catherine L. Lucero

Open Access Theses

A portion of the concrete pavements in the US have recently been observed to have premature joint deterioration. This damage is caused in part by the ingress of fluids, like water, salt water, or deicing salts. The ingress of these fluids can damage concrete when they freeze and expand or can react with the cementitious matrix causing damage. To determine the quality of concrete for assessing potential service life it is often necessary to measure the rate of fluid ingress, or sorptivity. Neutron imaging is a powerful method for quantifying fluid penetration since it can describe where water has penetrated, …

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Individual Analysis Of T2*-Weighted Gradient Echo Imaging In Asymptomatic And Symptomatic Athletes, Xianglun Mao Apr 2015

Individual Analysis Of T2*-Weighted Gradient Echo Imaging In Asymptomatic And Symptomatic Athletes, Xianglun Mao

Open Access Theses

Mild traumatic brain injury (mTBI), is a commonly occurred sports-related injury, especially in contact sports like football and soccer. Hemorrhage will appear as hypointense lesions on T2 *-weighted images, resulting from mTBI. Thus, T 2*-weighted gradient echo pulse sequence can be used to generate magnitude susceptibility-weighted (SW) images, and to further detect negative intensity changes of different regions of interests (ROIs) inside human brains. Our goal was to investigate how the ROI-specific intensity changes in each individual sports athlete over a single competition season and to interrogate whether these changes are correlated with repetitive subconcussive or …

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Computational Study Of Nano- And Meso-Scale Size Effects On Thermal Transport, Eshaan Mathew Apr 2015

Computational Study Of Nano- And Meso-Scale Size Effects On Thermal Transport, Eshaan Mathew

Open Access Theses

In the era where structures and devices are of the order of a few nanometers, a detailed understanding on the heat carriers in nanostructured devices is required to enable further improvements and advances. ^ In the first portion of this thesis we develop a new methodology using Molecular Dynamics (MD) to determine the thermal conductivity of argon with a modified Leonard Jones potential as a function of the modulation frequency input heat flux. We observe a decrease in the thermal conductivity as the heat transport enters the ballistic regime by an order of magnitude which agrees with some of the …

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Measurement, Characterization, And Effects Of Head Impacts In Women's Soccer, Emily C. Mccuen Apr 2015

Measurement, Characterization, And Effects Of Head Impacts In Women's Soccer, Emily C. Mccuen

Open Access Theses

The potential for long term neurological deficits resulting from repetitive head trauma is a major concern for collision sport athletes. Research conducted on football played has found neurophysiologic changes in the absence of concussion in athletes as early as high school age. Given that female soccer players show the highest rate of concussion for female athletes and a higher rate of concussion than their male counterparts, it is important to characterize the types of impacts female soccer athletes receive and assess female soccer athletes for neurophysiologic changes due to these impacts. This work paired head impact sensors with functional MRI …

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The Effect Of Integrated Science, Engineering, Technology, And Mathematics Lessons On Interest And Engagement Of Secondary Students, Cameron Nunan Apr 2015

The Effect Of Integrated Science, Engineering, Technology, And Mathematics Lessons On Interest And Engagement Of Secondary Students, Cameron Nunan

Open Access Theses

This study set out to answer the research question: Does teaching a single lesson, utilizing the interconnected principles of STEM in STEM courses, increase overall student interest and engagement in STEM classes in secondary schools? The literature review established a need for student interest in STEM to help fill future STEM careers. ^ Integrated STEM lessons were a viable option for increasing interest, but existing research on the matter was limited. Integrated STEM lessons were applied at a test site school using a multiple baseline framework and evaluated responses with a variation of the Intrinsic Motivation Inventory (IMI). According to …

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Flexible Weapons Architecture Design, William C. Pyant Apr 2015

Flexible Weapons Architecture Design, William C. Pyant

Open Access Theses

Present day air-delivered weapons are of a closed architecture, with little to no ability to tailor the weapon for the individual engagement. The closed architectures require weaponeers to make the target fit the weapon instead of fitting the individual weapons to a target. The concept of a flexible weapons aims to modularize weapons design using an open architecture shell into which different modules are inserted to achieve the desired target fractional damage while reducing cost and civilian casualties. This thesis shows that the architecture design factors of damage mechanism, fusing, weapons weight, guidance, and propulsion are significant in enhancing weapon …

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Preparation Of Bismuth Telluride Based Thermoelectric Nanomaterials Via Low-Energy Ball Milling And Their Property Characterizations, Christopher Robinson Apr 2015

Preparation Of Bismuth Telluride Based Thermoelectric Nanomaterials Via Low-Energy Ball Milling And Their Property Characterizations, Christopher Robinson

Open Access Theses

Thermoelectric materials are able to convert energy between heat and electricity with no moving parts, making them very appealing for power generation purposes. This is particularly appealing since many forms of energy generation lose energy to waste heat. The Livermore National Laboratory estimates that up to 55% of the energy created in traditional power plants is lost through heat generation [1]. As greenhouse gas emissions become a more important issue, large sources of waste like this will need to be harnessed. ^ Adoption of these materials has been limited due to the cost and efficiency of current technology. Bismuth telluride …

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Exploiting Intra-Warp Address Monotonicity For Fast Memory Coalescing In Gpus, Hector Rodriguez-Simmonds Apr 2015

Exploiting Intra-Warp Address Monotonicity For Fast Memory Coalescing In Gpus, Hector Rodriguez-Simmonds

Open Access Theses

Graphics Processing Units (GPUs) are growing increasingly popular as general purpose compute accelerators. GPUs are best suited for applications which have abundant data parallelism wherein the computation expressed as a single thread can be applied over a large set of data items. One key constraint that affects application performance on GPUs is that the underlying hardware is single-instruction, multiple data (SIMD) hardware which requires parallel instructions from the multiple threads to execute in a lock-step manner. The benefits of lock-step execution can be seriously degraded if the threads diverge (because of memory or branches). Specifically in the case of memory, …

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Spectral Broadening Of Frequency Combs Via Pulse Apodization Prior To Nonlinear Propagation, Oscar E. Sandoval Apr 2015

Spectral Broadening Of Frequency Combs Via Pulse Apodization Prior To Nonlinear Propagation, Oscar E. Sandoval

Open Access Theses

This thesis focuses on specific methods for spectrally broadening large repetition rate frequency combs using the idea that tailoring the shape of the seed pulse prior to nonlinear propagation will result in a spectrally flatter comb. A spectrally flat comb is desired for applications in optical communications, arbitrary waveform generation, and microwave photonic filtering. Three experimental setups using Fourier transform pulse shapers, Dispersion Decreasing Fiber (DDF) or Highly Nonlinear Fiber (HNLF) as the nonlinear propagation media were performed. Simulations employing the Split Step Fourier Method to solve the Nonlinear Schrödinger Equation were performed to analyze the experimental results. The first …

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