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Retrospective Theses and Dissertations

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Full-Text Articles in Physical Sciences and Mathematics

Development And Application Of A Hybrid Femtosecond/Picosecond Coherent Raman Probe Designed For Study Of Excited State Systems, Benjamin Douglas Prince Jan 2008

Development And Application Of A Hybrid Femtosecond/Picosecond Coherent Raman Probe Designed For Study Of Excited State Systems, Benjamin Douglas Prince

Retrospective Theses and Dissertations

The conversion from purely femtosecond coherent anti-Stokes Raman spectroscopy (CARS) to a more advantageous hybrid femtosecond/picosecond CARS (fs/ps CARS) probe for time-resolved vibrational dynamics studies is detailed. This probe provides a number of benefits for the use of studying the evolution of electronically excited states, including rapid data acquisition speeds, increased spectral resolution, and discrimination against competing background signals. The high time resolution is shown to depend on the cross correlation of the excitation pulse and initial CARS pulses while the high frequency resolution is shown to depend on the final CARS electric field. The pump-fs/ps CARS ...


Inverse Sturm-Liouville Problems Using Multiple Spectra, Mihaela Cristina Drignei Jan 2008

Inverse Sturm-Liouville Problems Using Multiple Spectra, Mihaela Cristina Drignei

Retrospective Theses and Dissertations

An eigenvalue problem for a Sturm-Liouville differential operator containing a parameter function and being studied on a given domain is a model for the infinitesimal, vertical vibration of a string of negligible mass, with the ends subject to various constraints. The parameter function of the Sturm-Liouville operator encodes information about the string (its density), and the eigenvalues of the same operator are the squares of the natural frequencies of oscillation of the string. In an inverse Sturm-Liouville problem one has knowledge about the spectral data of the operator and tries to recover the parameter function of the same operator. This ...


Laser Desorption/Ionization Mass Spectrometry For Direct Profiling And Imaging Of Small Molecules From Raw Biological Materials, Sangwon Cha Jan 2008

Laser Desorption/Ionization Mass Spectrometry For Direct Profiling And Imaging Of Small Molecules From Raw Biological Materials, Sangwon Cha

Retrospective Theses and Dissertations

Matrix-assisted laser desorption/ionization(MALDI) mass spectrometry(MS) has been widely used for analysis of biological molecules, especially macromolecules such as proteins. However, MALDI MS has a problem in small molecule (less than 1 kDa) analysis because of the signal saturation by organic matrixes in the low mass region. In imaging MS (IMS), inhomogeneous surface formation due to the co-crystallization process by organic MALDI matrixes limits the spatial resolution of the mass spectral image. Therefore, to make laser desorption/ionization (LDI) MS more suitable for mass spectral profiling and imaging of small molecules directly from raw biological tissues, LDI MS ...


Ultrafast Fluorescence Spectroscopy Used As A Probe To Explore Excited State Photophysics Of Biologically And Environmentally Relevant Systems, Prasun Mukherjee Jan 2008

Ultrafast Fluorescence Spectroscopy Used As A Probe To Explore Excited State Photophysics Of Biologically And Environmentally Relevant Systems, Prasun Mukherjee

Retrospective Theses and Dissertations

No abstract provided.


Studies In Electrophilic Cyclization, Palladium Migration And Cationic Polymerization, Tanay Kesharwani Jan 2008

Studies In Electrophilic Cyclization, Palladium Migration And Cationic Polymerization, Tanay Kesharwani

Retrospective Theses and Dissertations

2,3-Disubstituted benzo[b]selenophenes have been prepared by the electrophilic cyclization of various 1-(1-alkynyl)-2-(methylseleno)arenes by Br2, NBS, I2, ICl, PhSeCl, PhSeBr and Hg(OAc) 2. This method tolerates a wide variety of functional groups, including alcohol, ester, nitrile, nitro and silyl groups, and proceeds under exceptionally mild reaction conditions. A cationic intermediate in the cyclization with Br2 has been isolated and studied, providing evidence for a stepwise cyclization process.


Mesoporous Silica Nanomaterials And Magnetic Nanoparticles Based Stimuli-Responsive Controlled-Release Delivery Systems, Supratim Giri Jan 2008

Mesoporous Silica Nanomaterials And Magnetic Nanoparticles Based Stimuli-Responsive Controlled-Release Delivery Systems, Supratim Giri

Retrospective Theses and Dissertations

The research presented and discussed within this dissertation involves the development of mesoporous silica nanomaterials and magnetic nanoparticles based stimuli-responsive controlled-release delivery systems.;A superparamagnetic iron oxide nanoparticle-capped, MCM-41 type mesoporous silica nanorod-based controlled-release delivery system (Magnet-MSN) was synthesized. The stimuli-responsive release profiles of fluorescein-loaded Magnet-MSN delivery systems in the presence of external magnetic field was studied by using cell-produced antioxidants as triggers for releasing fluorescein molecules. The intracellular delivery efficiency of the Magnet-MSN system with human cervical cancer cells (HeLa) in vitro was demonstrated involving fluorescein molecules as model drug.;To take the advantage of the intracellular delivery capability ...


A Hydrogeologic Investigation Of Ada Hayden Lake In Ames, Iowa, Evan Gary Christianson Jan 2008

A Hydrogeologic Investigation Of Ada Hayden Lake In Ames, Iowa, Evan Gary Christianson

Retrospective Theses and Dissertations

Ada Hayden Lake, a 49.6 ha, gravel-pit lake containing 5.2 million m 3 of water, comprises the emergency water supply for Ames, Iowa. This study characterized and quantified groundwater/lake interaction for the assessment of water supply potential. Hydraulic head, delta18O, delta 2H, and 3H data collected from 23 piezometers show that Ada Hayden Lake is a flow-through lake. Geochemistry is characterized by high P concentrations (SRP=93.6 mug/L), denitrification, and methanogenesis. A 3-D, finite-difference groundwater flow model shows that groundwater contributes 85 percent of the lake's water budget and approximately 42 percent of the ...


Structural Induction: Towards Automatic Ontology Elicitation, Adrian Silvescu Jan 2008

Structural Induction: Towards Automatic Ontology Elicitation, Adrian Silvescu

Retrospective Theses and Dissertations

Induction is the process by which we obtain laws (and more encompassing - theories) about the world. This process can thought as aiming to derive two aspects of a theory: a Structural aspect and a Numerical aspect respectively. The Structural aspect is concerned with the entities modeled and their interrelationship, also known as ontology. The Numerical aspect is concerned with the quantities involved in the relationships among the above-mentioned entities along with uncertainties either postulated to exist in the world or inherent to the nature of the induction process.;In this thesis we will focus more on the structural aspect hence ...


Development Of Level Set Methods For Computing The Semiclassical Limit Of Schrödinger Equations With Potentials, Zhongming Wang Jan 2008

Development Of Level Set Methods For Computing The Semiclassical Limit Of Schrödinger Equations With Potentials, Zhongming Wang

Retrospective Theses and Dissertations

In this thesis, several level set methods are developed and analyzed for computing multi-valued solutions to the semiclassical limits of Schroedinger equations. Both formulation and numerical results are obtained for level set method. Superposition is also proved via let set method setting. Meanwhile, multi-valued solutions of the Euler-Poisson equations are also analyzed and computed using level set formulation via field space. Multi-scale computation and homogenization are studied for a class of Schroedinger equations. A Bloch band based level set method is developed with a series of numerical examples.


A Static Analysis Of Maximum Wind Penetration In Iowa And A Dynamic Assessment Of Frequency Response In Wind Turbine Types, Eknath Vittal Jan 2008

A Static Analysis Of Maximum Wind Penetration In Iowa And A Dynamic Assessment Of Frequency Response In Wind Turbine Types, Eknath Vittal

Retrospective Theses and Dissertations

As the energy industry moves into the 21st century the use and research into renewable resources has expanded significantly. Whether it is wind, biomass, or solar, the industry is seeking ways to breakthrough and integrate the newest technologies into their power systems. Wind energy, in particular, has seen significant expansion since the 1980's, with generating capability of wind turbines increasing dramatically from 50 kW to nearly 5 MW presently. Seeking to introduce larger levels of wind generation in the Iowa electricity system, the goal of this thesis was to: First, determine the maximum wind penetration level of the existing ...


Condenser: A Custom Tool For Capturing And Summarizing Network Traffic For Avalanche And Iseage, Jason Charles Maughan Jan 2008

Condenser: A Custom Tool For Capturing And Summarizing Network Traffic For Avalanche And Iseage, Jason Charles Maughan

Retrospective Theses and Dissertations

The Cyber-world is becoming an environment that is increasingly plagued by botnets and other programs adept at creating distributed and flooding-based attacks. These forms of assault are currently some of the most feared types of attacks being faced by networks.;The Internet Scale Event and Attack Generation Environment (ISEAGE) at Iowa State University, has been established to help researchers study actions and events that happen on the Internet. ISEAGE uses a custom tool, AVALANCHE, to simulate distributed and flooding-based attacks. While AVALANCHE is able to launch large quantities of attack packets, its ability to react and handle the enormity of ...


Photometric Variability Of Sun-Like Stars In The Old Open Cluster M67, Ryan Wesley Tobin Jan 2008

Photometric Variability Of Sun-Like Stars In The Old Open Cluster M67, Ryan Wesley Tobin

Retrospective Theses and Dissertations

Few physical processes can affect the earth's climate on a global scale. The variability of the Sun is one such process. The Sun is known to vary by about 0.1% due to Sunspots and other surface activity. We do not yet know whether the Sun's variability is normal. Using the well-known properties of the old open cluster M67, we look for variations in Sun-like stars.;In this thesis, we present the results of observation, calibration, correction and analysis of stars in M67. We focus on Sun-like stars and binary systems. We also determine the limits of observation ...


A Formal Approach Toward Authenticated Authorization Without Identification, Lucas D. Witt Jan 2008

A Formal Approach Toward Authenticated Authorization Without Identification, Lucas D. Witt

Retrospective Theses and Dissertations

Anonymity is a valued commodity on the Internet many uses take advantage of. Unfortunately, anonymity and credibility are essentially mutually exclusive. A practical method to determine request creditability without also inheriting the capability to identify the exclusive source of a request is not in practice. Previous research efforts have proposed methods to ensure anonymous communication, but most sacrifice either authorization or privacy. We propose a scheme that allows a message sender to prove his or her creditability without also providing any participant capability to identify the source. In addition, the scheme is resists sybil attacks and disjoints correlation of independent ...


Predicting Loads On Ground Engaging Tillage Tools Using Computational Fluid Dynamics, Mark Eugene Barker Jan 2008

Predicting Loads On Ground Engaging Tillage Tools Using Computational Fluid Dynamics, Mark Eugene Barker

Retrospective Theses and Dissertations

A new method of evaluating tillage tools using computational fluid dynamics is proposed. Steady-state CFD only and transient two-way fluid-structure interaction simulations were run to predict draft and vertical forces on a spring-reset field cultivator standard. Using CFD the soil was treated as a visco-plastic fluid using the Bingham-plastic material model. Lab tests were run using a rigid flat steel bar and a production field cultivator standard with 178 and 254 mm sweeps for comparison. The results indicate that the method can be used to reasonably predict the draft force to within three standard deviations of the average measured draft ...


Synthetic Data Methods For Disclosure Limitation, Jennifer C. Huckett Jan 2008

Synthetic Data Methods For Disclosure Limitation, Jennifer C. Huckett

Retrospective Theses and Dissertations

No abstract provided.


Decision Making Limitations From Communication Barriers In Government Structures In Chinese Rural Energy Projects, Nathan Gregory Johnson Jan 2008

Decision Making Limitations From Communication Barriers In Government Structures In Chinese Rural Energy Projects, Nathan Gregory Johnson

Retrospective Theses and Dissertations

Field research was conducted in the Li Cheng District (about 1,200 km 2) of Shan Dong Province. Data collection occurred during a two-week period in July 2006. At that time, seven villages represented all relevant sites in the district that contained gasification technologies. Small-group interviews with village leaders, station managers, and community members were conducted locally. Contact with external government agencies and technology scientists completed the set of potential stakeholders.;This study analyzes the failure of state-owned energy development initiatives in China. Communication barriers in bureaucratic structures and culturally prescribed patterns of interaction were revealed as inhibiting information transfer ...


Numerical Computation Of An Optimal Control Problem With Homogenization In One-Dimensional Case, Zhen Li Jan 2008

Numerical Computation Of An Optimal Control Problem With Homogenization In One-Dimensional Case, Zhen Li

Retrospective Theses and Dissertations

We consider an optimal control problem in which the state equation has rapidly oscillating coefficients (characterized by matrix A epsilon, where epsilon is a small parameter). Based on some important results from the paper by S. Kesavan, we convert this optimal control problem to a partial differential equation problem. Therefore, solving optimal control problem is equivalent to solving this partial differential equation problem. By several numerical examples in one dimensional case, we also show that the limit satisfies a problem of the same type but with matrix A 0 (the H-limit of Aepsi).


Influences Of Midtropospheric Perturbations On Summer Convective Storms Over The United States Northern Plains, Shih-Yu Wang Jan 2008

Influences Of Midtropospheric Perturbations On Summer Convective Storms Over The United States Northern Plains, Shih-Yu Wang

Retrospective Theses and Dissertations

No abstract provided.


Asymptotic Behavior Of The Solutions To A Family Of Pde's Arising From The Chemotaxis Equations Of Keller And Segal, Matthew Alan Halverson Jan 2008

Asymptotic Behavior Of The Solutions To A Family Of Pde's Arising From The Chemotaxis Equations Of Keller And Segal, Matthew Alan Halverson

Retrospective Theses and Dissertations

The system ut = uxx - (uvx)x, vt = u - Av is considered where A is a non-negative, self-adjoint operator which commutes with the Laplacian. The operator is considered to have eigenvalues lambda n = nrholambda1, and the system is considered on [0,1] x [0,T] with homogeneous Neumann boundary conditions. The operators which lead to global solutions and those that lead to solutions which blow up in finite time are considered as a function of rho, using an application of the methods of Hillen and Potapov [Math. Methods Appl. Sci., 27 (2004), pp. 1783-1801] to analyze the global case and those ...


Architectural Support For Secure And Survivable Embedded Software, Jesse Sathre Jan 2008

Architectural Support For Secure And Survivable Embedded Software, Jesse Sathre

Retrospective Theses and Dissertations

Attacks against vulnerable software have become a serious problem for industry and users alike. There have been many techniques proposed to combat these attacks which range from compiler modifications to additional architectural features. Most of these techniques focus on attack detection, while ignoring the problem of how to gracefully recover from such attacks. In this thesis we propose an architectural approach to attack detection and recovery which we call rollback and huddle. In our approach, a lightweight attack-detection module monitors a program's execution as its state is continuously checkpointed. In the case of an attack, the program state is ...


Performance Analysis And Optimization Of The Java Memory System, Carl Stephen Lebsack Jan 2008

Performance Analysis And Optimization Of The Java Memory System, Carl Stephen Lebsack

Retrospective Theses and Dissertations

No abstract provided.


Beyond The Arithmetic Constraint: Depth-Optimal Mapping Of Logic Chains In Reconfigurable Fabrics, Michael Todd Frederick Jan 2008

Beyond The Arithmetic Constraint: Depth-Optimal Mapping Of Logic Chains In Reconfigurable Fabrics, Michael Todd Frederick

Retrospective Theses and Dissertations

Look-up table based FPGAs have migrated from a niche technology for design prototyping to a valuable end-product component and, in some cases, a replacement for general purpose processors and ASICs alike. One way architects have bridged the performance gap between FPGAs and ASICs is through the inclusion of specialized components such as multipliers, RAM modules, and microcontrollers. Another dedicated structure that has become standard in reconfigurable fabrics is the arithmetic carry chain. Currently, it is only used to map arithmetic operations as identified by HDL macros. For non-arithmetic operations, it is an idle but potentially powerful resource.;Obstacles to using ...


Iseharvest: Tcp Packet Data Re-Assembler Framework For Network Traffic Content, Stephen Michael Eilers Jan 2008

Iseharvest: Tcp Packet Data Re-Assembler Framework For Network Traffic Content, Stephen Michael Eilers

Retrospective Theses and Dissertations

IseHarvest is a network analysis tool designed as a framework for extracting data from TCP streams. Once extracted, it reconstructs the data into individual files and documents from captured network traffic, saving the data locally. Besides being a framework, IseHarvest passively extracts HTTP data from captured traffic and reconstructs files and web directory layouts in such a way to enable web content monitoring of network resources. By re-linking HTML and CSS files, it provides an after the fact visual of how web sites were viewed over a network and a look at how corresponding web servers are laid out by ...


Study Of Left-Handed Materials, Jiangfeng Zhou Jan 2008

Study Of Left-Handed Materials, Jiangfeng Zhou

Retrospective Theses and Dissertations

Left handed materials (LHMs) are artificial materials that have negative electrical permittivity, negative magnetic permeability, and negative index of refraction across a common frequency band. They possess electromagnetic (EM) properties not found in nature. LHMs have attracted tremendous attention because of their potential applications to build the perfect lens and cloaking devices. In the past few years there has been ample proof for the existence of LHMs in the microwave frequency range. Recently, researchers are trying hard to push the operating frequency of LHMs into terahertz and the optical regime.;In this thesis, we start with the theoretical prediction of ...


Light-Trapping Enhancement In Thin Film Solar Cells With Photonic Crystals, Dayu Zhou Jan 2008

Light-Trapping Enhancement In Thin Film Solar Cells With Photonic Crystals, Dayu Zhou

Retrospective Theses and Dissertations

Photovoltaics (or solar cell) has been an active area for research and development, driven by the world's constantly increasing needs for power. Among the current solar technologies, thin film solar cell promises lower cost, but at the expense of lower power conversion efficiency. The efficiency of thin film solar cell can be improved using light confinement schemes commonly referred to as light-trapping. In this thesis, we develop novel light-trapping schemes utilizing photonic crystals (PCs). The optical modeling is performed with a rigorous scattering matrix approach, where Maxwell's equations are solved in Fourier space, and simulations are carried out ...


Encrypted Mal-Ware Detection, Bhuvaneswari Ramkumar Jan 2008

Encrypted Mal-Ware Detection, Bhuvaneswari Ramkumar

Retrospective Theses and Dissertations

Mal-ware such as viruses and worms are increasingly proliferating through out all networks. Existing schemes that address these issues either assume that the mal-ware is available in its plain-text format which can be detected directly with its signature or that its exploit-code execution is directly recognizable. Hence much of the development in this area has been focussed on generating more efficient signatures or in coming up with improved anomaly-based detection and pattern matching rules. However with "secure data" being the watch-word and several efficient encryption schemes being developed to obfuscate data and protect its privacy, encrypted mal-ware is very much ...


Reference Models For Network Trace Anonymization, Shantanu Gattani Jan 2008

Reference Models For Network Trace Anonymization, Shantanu Gattani

Retrospective Theses and Dissertations

Network security research can benefit greatly from testing environments that are capable of generating realistic, repeatable and configurable background traffic. In order to conduct network security experiments on systems such as Intrusion Detection Systems and Intrusion Prevention Systems, researchers require isolated testbeds capable of recreating actual network environments, complete with infrastructure and traffic details. Unfortunately, due to privacy and flexibility concerns, actual network traffic is rarely shared by organizations as sensitive information, such as IP addresses, device identity and behavioral information can be inferred from the traffic. Trace data anonymization is one solution to this problem. The research community has ...


Cryptic Backup: A Framework For Automated Compression, Encryption, And Backup Of Data, Christopher David Hoff Jan 2008

Cryptic Backup: A Framework For Automated Compression, Encryption, And Backup Of Data, Christopher David Hoff

Retrospective Theses and Dissertations

Historically, creating backups of valuable computer data has been arduous, tedious, and time consuming for the average computer user. The increasing concern of encrypting sensitive information has added another layer of complexity to the process. The challenge is creating a single product that encrypts and backs up data on an automated schedule. Likewise, it must decrypt and restore the data with ease. To specifically address this problem, the Cryptic Backup daemon was developed. The daemon schedules and automatically runs backup plans based on user preferences. To demonstrate the power of the daemon, the Cryptic Backup client application was developed. The ...


Comparison Of Esn, Urea, And Aqua Ammonia As Sources Of Nitrogen For Corn Production In Iowa, Jeffrey Allen Moore Jan 2008

Comparison Of Esn, Urea, And Aqua Ammonia As Sources Of Nitrogen For Corn Production In Iowa, Jeffrey Allen Moore

Retrospective Theses and Dissertations

Three nitrogen response studies were conducted in Iowa to compare the effect of a controlled release fertilizer, ESN, to urea and aqua ammonia (AA), on corn grain yields, biomass yields, and soil nitrate (NO3 --N) and ammonium (NH4+-N) concentrations. Experiments were conducted at two sites from 2003 through 2007 for the spring-applied ESN/urea study, two sites from 2006 through 2007 for the fall and spring-applied ESN/AA study, and one site from 2006 through 2007 for the spring applied ESN/AA study. N rates in the studies were 0-202 kg ha-1 in 34 kg N ha-1 increments in ...


The Evaluation Of Maize Genotypes For Potential Use In Cellulosic Ethanol Production, Krystal Marie Kirkpatrick Jan 2008

The Evaluation Of Maize Genotypes For Potential Use In Cellulosic Ethanol Production, Krystal Marie Kirkpatrick

Retrospective Theses and Dissertations

Corn stover represents a potential lignocellulosic feedstock that may benefit the emerging cellulosic ethanol industry. This study was conducted to determine dry matter yield and quality characteristics of maize stover, cob, and husk plant fractions, and to make predictions of potential ethanol yields. Detergent fiber predictions were made for each plant fraction using near infrared reflectance spectroscopy (NIRS). Predicted values were used to determine ethanol potential using a modified version of the National Renewable Energy Lab (NREL) theoretical ethanol yield calculator. Although significant, not as much variation was present among genotypes and plant fractions for chemical composition as for dry ...