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

Engineering Commons

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

144,533 Full-Text Articles 166,088 Authors 56,080,941 Downloads 298 Institutions

All Articles in Engineering

Faceted Search

144,533 full-text articles. Page 4130 of 4141.

Development Of A Sorbent For Carbon Dioxide, Dursun Can Ozcan 2010 Iowa State University

Development Of A Sorbent For Carbon Dioxide, Dursun Can Ozcan

Graduate Theses and Dissertations

The reversible absorption of CO2 by CaO at high temperature is a promising method for capturing and removing CO2 from a hot gas stream. The main challenge facing the use of this method is the deterioration of CO2 absorption capacity when the method is applied over a large number of CO2 absorption/desorption cycles. Although various techniques have been proposed for improving the cyclic stability and performance of calcium based sorbents, a cost effective method is still needed for industrial applications. Therefore, two promising methods for improving the cyclic stability were selected for further investigation. One method is to optimize ...


Using An Autothrottle To Compare Techniques For Saving Fuel On A Regional Jet Aircraft, Rebecca Marie Johnson 2010 Iowa State University

Using An Autothrottle To Compare Techniques For Saving Fuel On A Regional Jet Aircraft, Rebecca Marie Johnson

Graduate Theses and Dissertations

With rising fuel costs there is an initiative to conserve fuel during fight. Several methods have been proposed to calculate an optimum speed to y during cruise flight to maximize the range of a particular aircraft. This paper compares 11 of these methods using the same aircraft model and discusses how to implement these techniques in an autothrottle. Alternative implementations also include adding the algorithm to the Flight Management System to use during flight planning, or to including it in the databases to use during dispatch calculations. The results show that the speeds calculated by these methods are more fuel ...


Analysis Of The Passive Design And Solar Collection Techniques Of The Houses In The 2009 U.S. Department Of Energy's Solar Decathlon Competition, Timothy Robert Lentz 2010 Iowa State University

Analysis Of The Passive Design And Solar Collection Techniques Of The Houses In The 2009 U.S. Department Of Energy's Solar Decathlon Competition, Timothy Robert Lentz

Graduate Theses and Dissertations

The U.S. Department of Energy‘s Solar Decathlon is a competition in which twenty university teams compete to design and build the best completely solar powered house. The biennial competition culminates with the teams reconstructing their houses on the National Mall in Washington, DC for a week of tours and contests. In order for houses to be successful they must take advantage of passive solar design techniques while maximizing the solar energy collected through photovoltaic and thermal collectors.

Internal temperature, internal humidity, overall energy balance, site insolation, site temperature and site humidity data were measured for all twenty houses ...


Computational Intelligence And Transient Thermal Analysis Methods For Exploratory Analysis Of Source Air Quality, Gang Sun 2010 Iowa State University

Computational Intelligence And Transient Thermal Analysis Methods For Exploratory Analysis Of Source Air Quality, Gang Sun

Graduate Theses and Dissertations

INTRODUCTION

Over the last decade, with the trend toward larger more intensive animal feeding operations (AFOs) in the United States, ammonia (NH3), hydrogen sulfide (H2S), carbon dioxide (CO2) and particulate matter (PM10) generated and emitted from livestock production facilities have become a growing environmental concern for animal producers and nearby residents. Poor air quality inside the buildings can affect the health and productivity of farm workers and animals; while emissions of gas and dust beyond AFOs can influence the wellness of the neighboring residences, thus increasing the number of disputes and lawsuits against livestock operations.

To assess health and ecological ...


Graphics Hardware Acceleration For Rotorcraft Simulations, Mark William Lohry 2010 Iowa State University

Graphics Hardware Acceleration For Rotorcraft Simulations, Mark William Lohry

Graduate Theses and Dissertations

Interest in scientific programming using graphics processing units (GPUs) has exploded in recent years. The advent of NVIDIA's CUDA programming language in early 2007 enabled GPU acceleration of numerical software to become mainstream. Relative to central processing units (CPUs), these devices have extremely high floating point operation capability and memory bandwidth. Combined with relatively low cost, they are attractive alternatives to more expensive traditional supercomputers.

Porting existing computational fluid dynamics methods to the new hardware is not always straightforward. Modern GPUs are massively parallel, some consisting of over 400 processors, utilizing a unique hierarchy of computational units and memory ...


Structures, Kinetics, And Modeling Of Glycoside Hydrolase Family 44 Endoglucanases From Clostridium Acetobutylicum And Ruminococcus Flavefaciens Fd-1, Christopher Donald Warner 2010 Iowa State University

Structures, Kinetics, And Modeling Of Glycoside Hydrolase Family 44 Endoglucanases From Clostridium Acetobutylicum And Ruminococcus Flavefaciens Fd-1, Christopher Donald Warner

Graduate Theses and Dissertations

Glycoside hydrolases (GH) are enzymes that hydrolyze glycosidic bonds between carbohydrates. Family 44 contains endo- and xylo- glucanases capable of hydrolyzing cellulose and hemicelluose. Two members produced by Clostridium acetobutylicum and Ruminococcus flavefaciens FD-1 are the subjects of characterization work in this dissertation.

The EG from Clostridium acetobutylicum was characterized both structurally and kinetically. Crystallization and x-ray diffraction to 2.2-y resolution revealed a TIM barrel-like structure with additional ψ-loop and β-sandwich folds. The EG hydrolyzes cellotetraose and larger cellooligosaccharides, as well as carboxymethylcellulose and xylan at approximately the same rates. It converts lichenan to oligosaccharides of intermediate size and ...


Integral Equation Analysis Of Electromagnetic Wave Propagation In Periodic Structure And Error Analysis Of Various Basis Functions In Projection Of Plane Waves, Fu-gang Hu 2010 Iowa State University

Integral Equation Analysis Of Electromagnetic Wave Propagation In Periodic Structure And Error Analysis Of Various Basis Functions In Projection Of Plane Waves, Fu-Gang Hu

Graduate Theses and Dissertations

In the first part of this dissertation, the integral equation approaches are developed to analyze the wave propagation in periodic structures. Firstly, an integral equation approach is developed to analyze the two-dimensional (2-D) scattering from multilayered periodic array. The proposed approach is capable of handling scattering from the array filled with different media in different layers.

Combining the equivalence principle algorithm and connection scheme (EPACS), it can be avoided to find and evaluate the multilayered periodic Green's functions. For 2^N identical layers, the elimination of the unknowns between top and bottom surfaces can be accelerated using the logarithm ...


Fabrication And Modeling Of Thin-Film Anodic Titania Memristors, Kyle James Miller 2010 Iowa State University

Fabrication And Modeling Of Thin-Film Anodic Titania Memristors, Kyle James Miller

Graduate Theses and Dissertations

A new method for the fabrication of memristors is exhibited involving the

electrochemical anodization of titanium. This is an inexpensive, room temperature alternative to the current methods of fabrication. Two sets of devices were fabricated with varying anodization times and the devices were characterized. One set of the devices was annealed before characterization to evaluate the importance of annealing as stated in papers. The devices not annealed yielded memristive behavior due to oxygen vacancies created at the titanium-TiO2 junction buried below the surface of the device. The annealed devices behaved as resistors because the surface of the TiO2 ...


Spatio-Temporal Patterns Of Field-Scale Soil Moisture And Their Implications For In Situ Soil Moisture Network Design, Lingyuan Yang 2010 Iowa State University

Spatio-Temporal Patterns Of Field-Scale Soil Moisture And Their Implications For In Situ Soil Moisture Network Design, Lingyuan Yang

Graduate Theses and Dissertations

This dissertation describes efforts to overcome the challenges in designing in situ soil moisture observation network. The surface soil moisture data collected at two spatial scales in a working field in Iowa throughout the growing seasons in 2004 to 2008 were used to describe the spatio-temporal characteristics of soil moisture at field scale. The rank stability analysis was used to identify the locations on the ground to represent the mean soil moisture at the field scale across five different growing seasons. Optimal sampling locations (OSLs), giving accurate estimates of field mean soil moisture for each season, were selected using the ...


Utilizing Reactive Capability Of Doubly Fed Induction Generators To Enhance System Voltage Performance And Withstand Wind Variability, Pradip Vijayan 2010 Iowa State University

Utilizing Reactive Capability Of Doubly Fed Induction Generators To Enhance System Voltage Performance And Withstand Wind Variability, Pradip Vijayan

Graduate Theses and Dissertations

The fluctuating global fuel prices, concerns with the depleting fossil fuel reserves and concerns relating to climate change has resulted in an increasing focus on renewable sources to satisfy rising global energy requirements. Wind power is in the fore front of renewable power generation technologies. Within the realm of wind generators, the Doubly Fed Induction Generator (DFIG) is the preferred choice of installation worldwide.

Large scale penetration of wind energy in the system raises significant concerns regarding the reliability implications of the inherent variability of wind. The work presented in this thesis provides a methodology to utilize the capability curve ...


Obstacle-Avoiding Rectilinear Steiner Minimal Tree Construction, Gaurav Ajwani 2010 Iowa State University

Obstacle-Avoiding Rectilinear Steiner Minimal Tree Construction, Gaurav Ajwani

Graduate Theses and Dissertations

Obstacle-avoiding rectilinear Steiner minimal tree (OARSMT) construction

is becoming one of the most sought after problems in modern design

flow. In this thesis we present an algorithm to route a

multi-terminal net in the presence of obstacles. Ours is a top down

approach which includes partitioning the initial solution into

subproblems and using obstacle aware version of Fast Lookup Table based Wirelength Estimation (OA-FLUTE) at a lower level to generate an OAST followed by recombining them with some backend refinement. To construct an initial connectivity graph we use a novel obstacle-avoiding

spanning graph (OASG) algorithm which is a generalization of ...


Nonlinear Absorption And Free Carrier Recombination In Direct Gap Semiconductors, Peter D. Olszak 2010 University of Central Florida

Nonlinear Absorption And Free Carrier Recombination In Direct Gap Semiconductors, Peter D. Olszak

Electronic Theses and Dissertations

Nonlinear absorption of Indium Antimonide (InSb) has been studied for many years, yet due to the complexity of absorption mechanisms and experimental difficulties in the infrared, this is still a subject of research. Although measurements have been made in the past, a consistent model that worked for both picosecond and nanosecond pulse widths had not been demonstrated. In this project, temperature dependent two-photon (2PA) and free carrier absorption (FCA) spectra of InSb are measured using femtosecond, picosecond, and nanosecond IR sources. The 2PA spectrum is measured at room temperature with femtosecond pulses, and the temperature dependence of 2PA and FCA ...


Optimization Of Process Parameters For Reduced Thickness Cigses Thin Film Solar Cells, Shirish A. Pethe 2010 University of Central Florida

Optimization Of Process Parameters For Reduced Thickness Cigses Thin Film Solar Cells, Shirish A. Pethe

Electronic Theses and Dissertations

With the advent of the 21st century, one of the serious problems facing mankind is harmful effects of global warming. Add to that the ever increasing cost of fuel and the importance of development of clean energy resources as alternative to fossil fuel has becomes one of the prime and pressing challenges for modern science and technology in the 21st century. Recent studies have shown that energy related sources account for 50% of the total emission of carbon dioxide in the atmosphere. All research activities are focused on developing various technologies that are capable of converting sunlight into electricity with ...


Strains And Polarization Developed During Electric Field-Induced Antiferroelectric To Ferroelectric Phase Transformations In Lead Zirconate-Based Ceramics, Joshua Cody Frederick 2010 Iowa State University

Strains And Polarization Developed During Electric Field-Induced Antiferroelectric To Ferroelectric Phase Transformations In Lead Zirconate-Based Ceramics, Joshua Cody Frederick

Graduate Theses and Dissertations

Widespread adoption of renewable energy sources, such as wind and solar power, will necessitate an efficient way to interface with energy storage devices in order to ensure around-the-clock energy delivery during off-peak hours. Energy storage devices implementing linear dielectric capacitors offer exceptional power density (i.e. rate of charge/discharge), but cannot match the energy density (i.e. storage capacity) of batteries. However, replacing the linear dielectric in capacitors with an antiferroelectric material has the potential to increase the energy density by approximately one order of magnitude. Since the energy is stored via a reversible and diffusionless antiferroelectric-to-ferroelectric phase transformation ...


Using Functionalized Nanoparticles As Sensors For Rapid Monitoring Of Drinking Water Quality, Nan Xiao 2010 Iowa State University

Using Functionalized Nanoparticles As Sensors For Rapid Monitoring Of Drinking Water Quality, Nan Xiao

Graduate Theses and Dissertations

In this thesis, filed-deployable nano sensors for onsite detection of nitrite and microorganisms were developed. The colorimetric nitrite ion sensor was designed utilizing 4-aminothiophenol (4-ATP) modified gold nanorods (GNR). In the presence of nitrite ions, the deamination reaction was induced by heating the 4-ATP modified GNR in ethanol solution, resulting in the reduction of the GNR surface charges, which led to aggregation of GNRs and a colorimetric response that was quantitatively correlated to the concentration of nitrite ions. This simple assay was rapid (less than 10 minutes) and highly sensitive (< 1 ppm of nitrite), it can be used for rapid monitoring of drinking water quality. Anisotropic nanoparticles (i.e., silver nanocubes, gold nanorods) based SERS molecular probe were also designed and fabricated for the rapid and specific detection of bacterial targets in a test-in-a-tube platform utilizing a novel dual-recognition mechanism. The probes were synthesized by covalently attaching Raman tags and bacteria-specific antibodies to the surface of silver nanocubes. Specific binding between the probes and bacterial targets ensured surface enhanced Raman spectroscopic (SERS) signatures of the targets to be observed alongside with the SERS signals of the Raman tags. The assessment through the dual signals (superimposed target and tag Raman signatures) established a specific recognition of the targets in a single step, no washing/separation steps were needed to separate target-bound probes from unbound ones, because unbound probes only yield tag signatures, and could easily be distinguished from the target-bound ones. The dual-recognition protocol implemented with a portable Raman spectrometer would become an easy-to-use, field-deployable spectroscopic sensor for onsite detection of pathogenic microorganisms.


Designing Effective And Efficient Incentive Policies For Renewable In Generation Expansion Planning, Ying Zhou 2010 Iowa State University

Designing Effective And Efficient Incentive Policies For Renewable In Generation Expansion Planning, Ying Zhou

Graduate Theses and Dissertations

We present a bilevel optimization approach to designing effective and efficient incentive policies for promoting renewable energy. The effectiveness of an incentive policy is its capability to achieve a goal that would not be achievable without it. Renewable

portfolio standard is used in this thesis as the policy goal. The efficiency of an incentive policy is measured by the amount of intervention, such as taxes collected and subsidies

paid, to achieve the policy goal. We obtain the most effective and efficient incentive policies in the context of generation expansion planning, in which a planner makes investment decisions to serve project ...


Learning From Geometry In Learning For Tactical And Strategic Decision Domains, Jason Gauci 2010 University of Central Florida

Learning From Geometry In Learning For Tactical And Strategic Decision Domains, Jason Gauci

Electronic Theses and Dissertations

Artificial neural networks (ANNs) are an abstraction of the low-level architecture of biological brains that are often applied in general problem solving and function approximation. Neuroevolution (NE), i.e. the evolution of ANNs, has proven effective at solving problems in a variety of domains. Information from the domain is input to the ANN, which outputs its desired actions. This dissertation presents a new NE algorithm called Hypercube-based NeuroEvolution of Augmenting Topologies (HyperNEAT), based on a novel indirect encoding of ANNs. The key insight in HyperNEAT is to make the algorithm aware of the geometry in which the ANNs are embedded ...


Detection Of Recurring Software Vulnerabilities, Nam Hoai Pham 2010 Iowa State University

Detection Of Recurring Software Vulnerabilities, Nam Hoai Pham

Graduate Theses and Dissertations

Software security vulnerabilities are discovered on an almost daily basis and have caused substantial damage. It is vital to be able to detect and resolve them as early as possible. One of early detection approaches is to consult with the prior known vulnerabilities and corresponding patches. With the hypothesis that recurring software vulnerabilities are due to software reuse, we conducted an empirical study on several databases for security vulnerabilities and found several recurring and similar software security vulnerabilities occurring in different software systems. Most of recurring vulnerabilities occur in the systems that reuse source code, share libraries/APIs or reuse ...


Network Modeling In Systems Biology, Tian Xia 2010 Iowa State University

Network Modeling In Systems Biology, Tian Xia

Graduate Theses and Dissertations

A key aim of current systems biology research is to understand biology at the system level, to systematically catalogue all molecules and their interactions within a living cell, rather than the characteristics of isolated parts of a cell or organism. Network modeling is characterized by viewing cells in terms of their underlying network structure at many different levels of detail is a cornerstone of systems biology. Two emerging methodologies

in network modeling provide invaluable insights into biological systems: static large-scale biological network modeling and dynamic quantitative modeling. Static large-scale biological network modeling focuses on integrating, visualizing and topologically modeling

To ...


Fast-Response Liquid Crystal Displays, Meizi Jiao 2010 University of Central Florida

Fast-Response Liquid Crystal Displays, Meizi Jiao

Electronic Theses and Dissertations

After about five decades of extensive material research and device development, followed by massive investment in manufacturing technology, thin-film-transistor liquid-crystaldisplay (TFT-LCD) has finally become the dominant flat panel display technology. Nowadays, LCD performances, such as viewing angle, contrast ratio, and resolution, have reached acceptable levels. The remaining major technical challenges are response time, light efficiency, and sunlight readability. Fast response time is desired to reduce motion blur and to enable field sequential color displays using red (R), green (G), and blue (B) LEDs (light emitting diodes) without noticeable color breakup. Sequential RGB colors would eliminate the commonly used spatial color ...


Digital Commons powered by bepress