Open Access. Powered by Scholars. Published by Universities.®

Engineering Commons™

Open Access. Powered by Scholars. Published by Universities.®

Purdue University

Discipline
Keyword
Publication Year
Publication
Publication Type
File Type

Articles 2761 - 2790 of 6329

Full-Text Articles in Engineering

Numerical Simulation And Characterization Of Jet Flows In Indoor Environments, Zhu Shi Apr 2015

Numerical Simulation And Characterization Of Jet Flows In Indoor Environments, Zhu Shi

Open Access Theses

Jet flows are prevalent in indoor environment and other engineering applications. Typical examples in indoor environment include the flow discharged from personal ventilation systems, and the jet exhaled through breathing or coughing. When there is density (or temperature) difference between the jet and surroundings, jet flow becomes stratified jet. Due to its complication, stratified jet flow is difficult to model, especially in the developing or transitional region of the flow. Studying stratified jet flows is of great significance for understanding the mixing dynamics of jet and ambient environment. This is particularly important for optimizing indoor environment design, or obtaining accurate …

Go to article

Examining Unawareness Of Construction Law Principles From A Small Contractor's Perspective, Ketaki Shiralkar Apr 2015

Examining Unawareness Of Construction Law Principles From A Small Contractor's Perspective, Ketaki Shiralkar

Open Access Theses

Construction industry encompasses myriads of small trades within itself. If we take a microscope and observe, what looks from outside as one big single unit, is in fact made up of many small cogs of a wheel, important ones though, as without them, the functionality of the industry wouldn't be proper. As much as the existence of these small scale contractor's companies is important, so is their survival. There have been many reasons as to why contractors fail, but this study is limited to focus on one of them, which is, the absence of legal knowledge among employees of a …

Go to article

Machining As A Mechanical Property Test Revisited, David L. Smith Apr 2015

Machining As A Mechanical Property Test Revisited, David L. Smith

Open Access Theses

There is much need for data on mechanical behavior of metals at high strains and strain rates. This need is dictated by modeling of processes like forming and machining, wherein the material in the deformation zone is subjected to severe deformation conditions atypical of conventional material property tests such as tension and torsion. Accurate flow stress data is an essential input for robust prediction of process outputs. Similar requirements arise from applications in high speed ballistic penetration and design of materials for armor. Since the deformation zone in cutting of metals is characterized by unique and extreme combinations of strain, …

Go to article

Failure Analysis Of High Performance Ballistic Fibers, Jennifer S. Spatola Apr 2015

Failure Analysis Of High Performance Ballistic Fibers, Jennifer S. Spatola

Open Access Theses

High performance fibers have a high tensile strength and modulus, good wear resistance, and a low density, making them ideal for applications in ballistic impact resistance, such as body armor. However, the observed ballistic performance of these fibers is much lower than the predicted values. Since the predictions assume only tensile stress failure, it is safe to assume that the stress state is affecting fiber performance. The purpose of this research was to determine if there are failure mode changes in the fiber fracture when transversely loaded by indenters of different shapes. An experimental design mimicking transverse impact was used …

Go to article

Dynamics Of Transitions Between Capillary Stable States Under Weightlessness, Praveen Srikanth Apr 2015

Dynamics Of Transitions Between Capillary Stable States Under Weightlessness, Praveen Srikanth

Open Access Theses

The study of two phase systems with one of the phases obstructing the other is of importance in a lot of fields. Liquid droplets in airways and air bubbles in the blood stream both fall under this category of problems. Helium bubbles in hydrazine fuel lines of satellites also have been found to cause frequent thruster shutdown and also seriously affect spacecraft control. Studies have been carried out until now to look at static equilibrium topologies and stability of such two phase systems in straight, bent and laterally compressed capillaries. In this investigation we look at the dynamics of the …

Go to article

Design And Heat Transfer Analysis Of Accelerating Distributed Combustion System, Yashovardhan U. Wagh Apr 2015

Design And Heat Transfer Analysis Of Accelerating Distributed Combustion System, Yashovardhan U. Wagh

Open Access Theses

Over the past few decades, there has been a significant increase in greenhouse gases such as CO2, N2O, and CH4 produced from gas turbine engines. Keeping this in mind, current research work is being carried out for reducing NOx produced from combustors. The objective of this research is to determine the feasibility of Distributed Combustion Systems (DCS) for increasing efficiency and reducing NOx emissions. ^ A DCS has a main combustion zone (MCZ) where 90% of the fuel is burned and is followed by a secondary combustion zone (SCZ) in which jets carrying fuel are …

Go to article

Ads-B Used In Improvement Of Air Traffic Control, Hao Wang Apr 2015

Ads-B Used In Improvement Of Air Traffic Control, Hao Wang

Open Access Theses

Automatic dependent surveillance – broadcast (ADS-B) is a central component of the NextGen air traffic control program. This surveillance technology can replace current secondary surveillance radars (SSR) and improve cockpit situational awareness. The service can improve traffic surveillance capabilities by sharing accurate aircraft position information between pilots and air traffic controllers. In addition, ADS-B provides pilots with weather as well as air traffic information for nearby area. In order to receive these traffic and weather services, a pilot must have appropriate onboard equipment including GPS receiver, Universal Access Transceiver, antenna and multi-function cockpit display which is capable of receiving and …

Go to article

An Experimental Investigation Of A Premixed Laminar Flame Using Tunable Diode Laser And Quantitative Imaging Of Radiation Intensity, Weichao Wang Apr 2015

An Experimental Investigation Of A Premixed Laminar Flame Using Tunable Diode Laser And Quantitative Imaging Of Radiation Intensity, Weichao Wang

Open Access Theses

Simultaneous CO concentration and temperature measurements using Tunable Diode Laser Absorption Spectroscopy (TDLAS) are reported in this study. Ro-vibrational transitions of CO, R(27) and R(6) are used for probing absorbance profiles. Premixed ethylene-air flat flame on a McKenna burner is used for creating combustion gaseous products at equivalence ratio 0.83 to 1.82. Nitrogen shroud flow is used for preventing air mixing. Both Direction Absorption (DA) and Wavelength Modulation Spectroscopy (WMS) experiments are conducted. Experimental results are compared with literature and simulation using CHEMKIN and chemical equilibrium. Reasonable agreements are achieved between experiment and simulation. The CO detection limit is determined …

Go to article

Recursive Tree Traversal Dependence Analysis, Yusheng Weijiang Apr 2015

Recursive Tree Traversal Dependence Analysis, Yusheng Weijiang

Open Access Theses

While there has been much work done on analyzing and transforming regular programs that operate over linear arrays and dense matrices, comparatively little has been done to try to carry these optimizations over to programs that operate over heap-based data structures using pointers. Previous work has shown that point blocking, a technique similar to loop tiling in regular programs, can help increase the temporal locality of repeated tree traversals. Point blocking, however, has only been shown to work on tree traversals where each traversal is fully independent and would allow parallelization, greatly limiting the types of applications that this transformation …

Go to article

Investigation Of Industry Perceptions Of Building Information Modeling (Bim)-Based Estimating Practices In The U.S. And China, Zhihang Yi Apr 2015

Investigation Of Industry Perceptions Of Building Information Modeling (Bim)-Based Estimating Practices In The U.S. And China, Zhihang Yi

Open Access Theses

While the Building Information Modeling (BIM) technology has been seen as next revolutionary technology for the Architectural, Engineering, Construction and Facility Management (AEC/FM) fields, the AEC/FM industry does not implement BIM technology on the cost estimating practices as widely as expected. The efficiency improvement on cost estimating with BIM could be accomplished through automating quantity take-offs, closely collaborating design with the estimating professionals and so on. This research explores the advantages and barriers of imbedding BIM technology into the estimating practices which enables the industry deepen their understandings on BIM-based cost estimation method. This study also compares the industry perceptions …

Go to article

Linear Matrix Inequality-Based Nonlinear Adaptive Robust Control With Application To Unmanned Aircraft Systems, David William Kun Apr 2015

Linear Matrix Inequality-Based Nonlinear Adaptive Robust Control With Application To Unmanned Aircraft Systems, David William Kun

Open Access Theses

Unmanned aircraft systems (UASs) are gaining popularity in civil and commercial applications as their lightweight on-board computers become more powerful and affordable, their power storage devices improve, and the Federal Aviation Administration addresses the legal and safety concerns of integrating UASs in the national airspace. Consequently, many researchers are pursuing novel methods to control UASs in order to improve their capabilities, dependability, and safety assurance. The nonlinear control approach is a common choice as it offers several benefits for these highly nonlinear aerospace systems (e.g., the quadrotor). First, the controller design is physically intuitive and is derived from well known …

Go to article

Loss Of Accuracy Using Smeared Properties In Composite Beam Modeling, Ning Liu Apr 2015

Loss Of Accuracy Using Smeared Properties In Composite Beam Modeling, Ning Liu

Open Access Theses

Advanced composite materials have broad, proven applications in many engineering systems ranging from sports equipment sectors to components on the space shuttle because of their lightweight characteristics and significantly high stiffness. Together with this merit of composite materials is the challenge of improving computational simulation process for composites analysis. Composite structures, particularly composite laminates, usually consist of many layers with different lay-up angles. The anisotropic and heterogeneous features render 3D finite element analysis (FEA) computationally expensive in terms of the computational time and the computing power. ^ At the constituent level, composite materials are heterogeneous. But quite often one homogenizes …

Go to article

Using Mixtures Of Fatty Acid Methyl Esters As Phase Change Materials For Concrete, Leah Christine Liston Apr 2015

Using Mixtures Of Fatty Acid Methyl Esters As Phase Change Materials For Concrete, Leah Christine Liston

Open Access Theses

Phase change materials (PCMs) are an effective way of storing/releasing thermal energy via phase transformations. Incorporating PCMs into concrete pavements at airports has been suggested as a means to reduce the accumulation of snow and ice on runways. This thesis reports on the development of two phase change materials composed of binary mixtures of fatty acid methyl esters (FAME) which provide a solid-liquid transition slightly above 0°C with a high enthalpy of fusion. Current findings of this study indicate that these mixtures have the necessary properties to be a high performance PCM with the potential to reduce the levels of …

Go to article

Real-Time Rss-Based Indoor Navigation For Autonomous Uav Flight, Sangjun Lee Apr 2015

Real-Time Rss-Based Indoor Navigation For Autonomous Uav Flight, Sangjun Lee

Open Access Theses

Navigation for the autonomous flight of Unmanned Aerial Vehicles (UAVs) in an indoor space has attracted much attention recently. One of the main goals of an indoor navigation system is developing an alternative method to obtain position information that can replace or complement the global positioning system. While much research has focused on vision-based indoor navigation systems, this paper aims to develop a Received Signal Strength (RSS)-based navigation system, which is a more cost effective alternative. Then, the position and attitude of a UAV can be computed by the fusion of RSS measurements and measurements from the onboard inertial measurement …

Go to article

An Empirical Approach To The Re-Creation Of Vehicle Drive Cycles, Andrew J. Larson Apr 2015

An Empirical Approach To The Re-Creation Of Vehicle Drive Cycles, Andrew J. Larson

Open Access Theses

Vehicles such as buses, delivery trucks, mining equipment, and motorsport vehicles often repeat a highly defined pattern, route, or track during normal use. For these vehicles, standard dynamometer drive cycles are of little use. It was proposed that deriving a vehicle drive cycle from empirical data collected from on-board vehicle sensors would produce more accurate vehicle characteristic predictions for special purpose vehicles. This study answers the question "Is it possible to use recorded vehicle data to replicate a real world driving scenario for the purpose of vehicle diagnostics?" To reduce the complexity of the project, an electric go-kart was used …

Go to article

A Nearly Autonomous, Platform-Independent Mobile App For Manure Application Records, Matthew R. Koester Apr 2015

A Nearly Autonomous, Platform-Independent Mobile App For Manure Application Records, Matthew R. Koester

Open Access Theses

A major part of modern manure management is accurate application records; a key to their creation and maintenance is ease. This project involved the integration of existing technologies (smartphones, Bluetooth tags) in mobile web and native Android applications (apps) which enable the autogenic creation and upkeep of manure hauling records. This approach greatly improves the efficiency of the recording process which should help to improve the management of applied nutrients. Features of the app include: computation of a suggested travel speed to ensure target nutrient application (based on desired application rate and spreading width); minimized keystrokes/screen taps to accurately capture …

Go to article

Dielectric Coating Of Iron Particles By Electrostatic Colloidal Deposition, Daniel Kim Apr 2015

Dielectric Coating Of Iron Particles By Electrostatic Colloidal Deposition, Daniel Kim

Open Access Theses

Iron is a soft magnetic material widely used in electric motors, generators, and transformers because they demand high permeability and low core loss. The main goal of this project is to develop a commercially viable coating of iron powders for press-and-sinter processing that would enable higher firing temperatures to anneal out magnetic defects, while maintaining high electrical resistivity (∼10,000 μΩ-cm) and high iron density (>90 %). An alumina-modified colloidal silica (LUDOX CL), was used in early work to make Fe (-)/SiO2 (+) in a wet-pressed route. The highest relative density and resistivity measurements for a wet-pressing route were …

Go to article

Hybrid Power System For Micro Air Vehicles, Bakytgul Khaday Apr 2015

Hybrid Power System For Micro Air Vehicles, Bakytgul Khaday

Open Access Theses

Today Micro Air Vehicles are in need of a good power source that would enable them longer flight time and various functionalities. This work is focused on to this problem. A possible solution that is offered in this study is implementing a hybrid power system consisting of battery and supercapacitor (SCAP). The proposed hybrid power system was tested on an existing MAV platform (Cheerson CX-10). A separate hybrid power printed circuit board (PCB) was designed and manufactured. For experimental and system verification purposes, the PCB was not sized for on-board flight. The hybrid power PCB was connected to MAV through …

Go to article

Four Runway Configuration Types And Their Relation To Arrival Delays, Rachel Jayne Kennedy Apr 2015

Four Runway Configuration Types And Their Relation To Arrival Delays, Rachel Jayne Kennedy

Open Access Theses

Aside from a safe flight, airline passengers expect to arrive to their destination on time. With an abundance of flights in the United States arriving late each day, it has yet to be determined if the airport's layout plays a role. This research looks at four common runway configuration types at hub and non-hub airports to determine if runway configurations affect arrival delays. A two-way ANOVA is conducted comparing the means of the on-time arrival percentage between airports exhibiting each of the four runway configurations as well as hub and non-hub airport status. The results determine if any or none …

Go to article

Hubcheck: Check The Hub, Derrick S. Kearney Apr 2015

Hubcheck: Check The Hub, Derrick S. Kearney

Open Access Theses

The HUBzero Platform is a framework for building websites, referred to as "hubs," that promote research communities through online simulation, data management, and collaboration. With each software release, the HUBzero Team dedicates weeks of team members' time toward manually testing, fixing, and retesting hub components. The unique mixture of environments that make up a hub makes using existing automated testing solutions hard and shifts the burden of testing to humans, promoting variation, spot checking of fixes, and other shortcuts to avoid the high cost of completely retesting the system. With over twenty hubs being actively managed by the HUBzero Team, …

Go to article

Computational Valve Plate Design, Paul K. Kalbfleisch Apr 2015

Computational Valve Plate Design, Paul K. Kalbfleisch

Open Access Theses

Axial piston machines are widely used in many industries for their designs compactness, flexibility in power transfer, variable flow rate, and high efficiencies as compared to their manufacturing costs. One important component of all axial piston machines that is a very influential on the performance of the unit is the valve plate. The aim of this research is to develop a design methodology that is general enough to design all types of valve plates and the simple enough not to require advanced technical knowledge from the user. A new style of valve plate designs has been developed that comprehensively considers …

Go to article

Mass Transfer Of Large Molecules Through Collagen And Collagen-Silica Hybrid Membranes, Pedro Jofre Lora Apr 2015

Mass Transfer Of Large Molecules Through Collagen And Collagen-Silica Hybrid Membranes, Pedro Jofre Lora

Open Access Theses

Diabetes is a growing concern in the United States and around the world that must be addressed through new treatment options. Current standard treatment options of diabetes are limiting and have tremendous impacts on patient's lives. Emerging therapies, such as the implantation of encapsulated islets, are promising treatment options, but have not yet materialized due to unsolved problems with material properties. Hybrid silica-collagen membranes address some of these unsolved problems and are a promising material for cell encapsulation. However, the mass transfer properties of large molecules, such as insulin, TNF-α, IL1β, and other important proteins in the etiology of diabetes, …

Go to article

Optimal Start-Up Control Of An Evaporation System Modeled As An Interconnected Hybrid Dynamical System, Rithesh Iyer Apr 2015

Optimal Start-Up Control Of An Evaporation System Modeled As An Interconnected Hybrid Dynamical System, Rithesh Iyer

Open Access Theses

The purpose of this research is to investigate the feasibility and advantageous outcomes of modeling a complicated non-linear hybrid dynamical process as an interconnected dynamical system for the purpose of solving a hybrid optimal control problem under the framework of nonlinear model predictive control. This work considers a hybrid model of the startup process of an evaporation system. In this evaporation system a liquid containing mixture of a non-volatile component A and volatile solvents B (water) and C (alcohol) is heated to evaporate the solvents and obtain component A at a higher concentration using a column that is temperature controlled …

Go to article

Downward Model Development Of The Soil Moisture Accounting Loss Method In Hec-Hms: Revelations Concerning The Soil Profile, Jessica Holberg Apr 2015

Downward Model Development Of The Soil Moisture Accounting Loss Method In Hec-Hms: Revelations Concerning The Soil Profile, Jessica Holberg

Open Access Theses

Despite the fact that the soil profile is known to impact streamflow, most Curve Number (CN)-based models ignore subsurface processes. This study explores the influence of soil storage on peak flows. Two watersheds in flat, humid west-central Indiana were modeled using both the Natural Resources Conservation Service (NRCS) Curve Number and four versions of the Soil Moisture Accounting (SMA) loss methods in the United States Army Core of Engineers-developed (USACE) Hydrologic Engineering Center Hydrologic Modeling System (HEC-HMS). One watershed encompasses the Wabash and Tippecanoe Rivers' confluence; the other contains an ephemeral stream, Plum Creek. The CN-based model was developed using …

Go to article

Understanding Mechanical Environment Changes And Biological Responses To Canine Retraction Using T-Loop, Feifei Jiang Apr 2015

Understanding Mechanical Environment Changes And Biological Responses To Canine Retraction Using T-Loop, Feifei Jiang

Open Access Dissertations

Jiang, Feifei. Ph.D., Purdue University, May 2015. Understanding Mechanical Environment Changes and Biological Responses to Canine Retraction Using T-loop. Major Professors: Jie Chen, School of Engineering and Technology, Anil Bajaj, School of Mechanical Engineering. Predictability of tooth displacement in response to specific orthodontic load system directly links to the quality and effectiveness of the treatment. The key questions are how the tooth's environment changes in response to the orthodontic load and how the biological tissues respond clinically. The objectives of this study are to determine the mechanical environment (ME) changes and to quantify the biological tissues' response. Eighteen (18) patients …

Go to article

Black-Box Printer Models And Their Applications, Yanling Ju Apr 2015

Black-Box Printer Models And Their Applications, Yanling Ju

Open Access Dissertations

In the electrophotographic printing process, the deposition of toner within the area of a given printer addressable pixel is strongly influenced by the values of its neighboring pixels. The interaction between neighboring pixels, which is commonly referred to as dot-gain, is complicated. The printer models which are developed according to a pre-designed test page can either be embedded in the halftoning algorithm, or used to predict the printed halftone image at the input to an algorithm being used to assess print quality. In our research, we examine the potential influence of a larger neighborhood (45?45) of the digital halftone image …

Go to article

Transport Studies In Graphene-Based Materials And Structures, Jiuning Hu Apr 2015

Transport Studies In Graphene-Based Materials And Structures, Jiuning Hu

Open Access Dissertations

Graphene, a single atomic layer of graphite, has emerged as one of the most attractive materials in recent years for its many unique and excellent properties, inviting a broad area of fundamental studies and applications. In this thesis, we present some theoretical/experimental studies about the thermal, electronic and thermoelectric transport properties in graphene-based systems. We employ the molecular dynamic simulations to study the thermal transport in graphene nanoribbons (GNRs) exhibiting various properties, including chirality dependent thermal conductivity, thermal rectification in asymmetric GNRs, defects and isotopic engineering of the thermal conductivity and negative differential thermal conductance (NDTC) at large temperature biases. …

Go to article

Design Of Transfers From Earth-Moon L 1/L2 Libration Point Orbits To A Destination Object, Masaki Kakoi Apr 2015

Design Of Transfers From Earth-Moon L 1/L2 Libration Point Orbits To A Destination Object, Masaki Kakoi

Open Access Dissertations

Within the context of both manned and robotic spaceflight activities, orbits near the Earth-Moon L1 and L2 libration points could support lunar surface operations and serve as staging areas for future missions to near-Earth asteroids as well as Mars. In fact, an Earth-Moon L2 libration point orbit has been proposed as a potential hub for excursions to Mars as well as activities in support of planetary exploration. Yet, the dynamical environment within the Earth-Moon system is complex and, consequently, trajectory design in the vicinity of Earth-Moon L1 and L2 is nontrivial. Routine transfers between an Earth-Moon L1/L2 facility and Mars …

Go to article

Experimental Constraints On Exotic Spin-Dependent Interactions Using Specialized Materials, Rakshya Khatiwada Apr 2015

Experimental Constraints On Exotic Spin-Dependent Interactions Using Specialized Materials, Rakshya Khatiwada

Open Access Dissertations

Various theories predict the possible existence of symmetry violating forces with mesoscopic range interactions from mm-m [1]. These forces can arise from the coupling of a spin 0 boson to spin 1/2 fermions through scalar (gs) and pseudoscalar (gp) couplings. We discuss two experiments that can investigate these interactions using nucleon rich, impressively low magnetic susceptibility (5-100 times lower than pure water) test masses and electron-spin rich, polarized test masses (spin density: 10^20 h/cm3 ). The first experiment looks for a P-odd, T-odd interaction potential proportional to (S.r) where S is the spin of one particle and r is the …

Go to article

An Integrated System Of Vapor-Compression Chiller And Absorption Heat Pump: Experiment, Modeling, And Energy And Economic Evaluation, Yi-Shu Kung Apr 2015

An Integrated System Of Vapor-Compression Chiller And Absorption Heat Pump: Experiment, Modeling, And Energy And Economic Evaluation, Yi-Shu Kung

Open Access Dissertations

Buildings currently consume 41% of the primary energy in the United States. Among the 41% primary energy, approximate 50% are used for building heating, cooling, and water heating. Improving the efficiencies of the devices for building heating and cooling has potentials to reducing the energy consumptions. This research aims to find one solution for building energy efficiency through investigating an Integrated System of an Integrated Compression-Absorption Subcooling System (ICASS) Based upon the principle of subcooling effect, the ICASS can improve the efficiency of the cooling device but also achieve additional useful heating sources potentially used for space heating and domestic …

Go to article

First Prev Next Last