Digital Commons Network^™

Mechanistic-Empirical Modeling In Network-Level Pavement Management, Scott Schram, Magdy Abdelrahman

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Researchers and practitioners have long recognized the advantages of mechanistic modeling. As agencies implement the Guide for Mechanistic-Empirical Design of New and Rehabilitated Pavement Structures [referred to as the Mechanistic-Empirical Pavement Design Guide (MEPDG)] in the local project-level pavement management system (PMS), its potential as a planning tool in network-level analyses remains unrecognized. A unique, large-scale application of MEPDG is presented. The Nebraska Department of Roads uses a decision tree that systematically screens and identifies candidates for entry into a multiyear optimization program. The process uses linear deterioration rates that have been shown to provide an R² value as …

The Design By Molecular Dynamics Modeling And Simulations Of Porous Polymer Adsorbent Media Immobilized On The Throughpore Surfaces Of Polymeric Monoliths, E. Riccardi, J. C. Wang, A. I. Liapis

Chemical and Biochemical Engineering Faculty Research & Creative Works

Ion-exchange porous adsorbent media having intermediate and low surface densities of dextran polymer grafted on the surface of the through pores of polymeric monoliths are constructed and characterized by a molecular dynamic modeling and simulation approach that has also been shown to be effective in the construction and characterization of porous ion-exchange adsorbent media whose number of immobilized dextran polymer chains per unit surface area is high. the activation step that prepares the surface of the pores of the dextran polymer layer for the immobilization of the charged ligands insignificantly affected the pore structure of the dextran polymer layer, while …

Predicting The Perforation Response Of Honeycomb Sandwich Panels Using Ballistic Limit Equations, William P. Schonberg, Frank Schäfer, Robin Putzar

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Man-made debris from previous spacecraft missions poses a serious threat to spacecraft that are launched to operate in Earth orbit because it can strike such spacecraft at extremely high velocities and consequently damage mission-critical systems. Most satellites are constructed with honeycomb sandwich panels as their primary structural elements. to be able to perform a risk analysis, it is important to know, in the event of such a meteoroid or orbital debris particle impact, whether or not the impacting particle or parts thereof will exit the rear of the sandwich panel. a recently developed set of ballistic limit equations for two …

Extensions Of Effective-Medium Theory Of Transport In Disordered Systems, V. M. Kenkre, Z. Kalay, Paul Ernest Parris

Physics Faculty Research & Creative Works

The effective-medium theory of transport in disordered systems, whose basis is the replacement of spatial disorder by temporal memory, is extended in several practical directions. Restricting attention to a one-dimensional system with bond disorder for specificity, a transformation procedure is developed to deduce explicit expressions for the memory functions from given distribution functions characterizing the system disorder. It is shown how to use the memory functions in the Laplace domain forms in which they first appear, and in the time domain forms which are obtained via numerical inversion algorithms, to address time evolution of the system beyond the asymptotic domain …

Infinite-Randomness Quantum Critical Points Induced By Dissipation, Thomas Vojta, Chetan Kotabage, Jose A. Hoyos

Physics Faculty Research & Creative Works

We develop a strong-disorder renormalization group to study quantum phase transitions with continuous O(N) symmetry order parameters under the influence of both quenched disorder and dissipation. For Ohmic dissipation, as realized in Hertz's theory of the itinerant antiferromagnetic transition or in the superconductor-metal transition in nanowires, we find the transition to be governed by an exotic infinite-randomness fixed point in the same universality class as the (dissipationless) random transverse-field Ising model. We determine the critical behavior and calculate key observables at the transition and in the associated quantum Griffiths phase. We also briefly discuss the cases of super-Ohmic and sub-Ohmic …

Infinite-Randomness Critical Point In The Two-Dimensional Disordered Contact Process, Thomas Vojta, A. Farquhar, J. Mast

Physics Faculty Research & Creative Works

We study the nonequilibrium phase transition in the two-dimensional contact process on a randomly diluted lattice by means of large-scale Monte Carlo simulations for times up to 1010 and system sizes up to 8000×8000 sites. Our data provide strong evidence for the transition being controlled by an exotic infinite-randomness critical point with activated (exponential) dynamical scaling. We calculate the critical exponents of the transition and find them to be universal, i.e., independent of disorder strength. The Griffiths region between the clean and the dirty critical points exhibits power-law dynamical scaling with continuously varying exponents. We discuss the generality of our …

Risk Indexes For Draft Ccl3 Chemicals, J. Alan Roberson, Matthew Lueders, Craig Adams, Jeffrey S. Rosen

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

To supplement the processes used for developing the draft third Contaminant Candidate List (CCL3) and better inform decisions made by the US Environmental Protection Agency on future CCLs, the authors offer an evaluation tool for efficiently synthesizing, visualizing, and organizing data for effective comparisons among contaminants. Graphical presentations of health effects-occurrence indexes were developed for more than 300 chemical contaminants, including those on the draft CCL3. a risk indexes framework was then used to elucidate the extent of available data, the data quality, and the underlying uncertainties for occurrence and toxicity. Choosing the appropriate contaminant for regulation is a complex …

Esd Current Spread Measurement Using Mesh Structure, Jae-Deok Lim, David Pommerenke, Jong-Sung Lee, Byong-Su Seol

Electrical and Computer Engineering Faculty Research & Creative Works

If a PCB is struck by an ESD the injected current spreads throughout the PCB and returns via attached cables. During the current spread a variety of effects occur: The current spreads on the main ground and power planes, couples into traces and IC lead-frames and bond wires. Further, the PCB and the attached cables can form resonators causing ringing at their natural resonance frequencies. Understanding the current spread onto a PCB, best, also onto the traces is of great importance for gaining insight into ESD related problems on products. A test setup has been created that allows capturing and …

Mobile Speed Estimation For Broadband Wireless Communications Over Rician Fading Channels, Y. Rosa Zheng, Chengshan Xiao

Electrical and Computer Engineering Faculty Research & Creative Works

In this paper, a new algorithm is proposed to estimate mobile speed for broadband wireless communications, which often encounter large number of fading channel taps causing severe intersymbol interference. Different from existing algorithms, which commonly assume that the fading channel coefficients are available for the speed estimators, the proposed algorithm is based on the received signals which contain unknown transmitted data, unknown frequency selective fading channel coefficients possibly including line-of-sight (LOS) components, and random receiver noise. Theoretical analysis is first carried out from the received signals, and a practical algorithm is proposed based on the analytical results. The algorithm employs …

Neural Network Demodulation For An Optical Sensor, Rohit Dua, Steve Eugene Watkins, Donald C. Wunsch

Electrical and Computer Engineering Faculty Research & Creative Works

Methods and systems of neural network demodulation for an optical sensor. An optical sensor may be coupled to a structure and be capable of reflecting a reflected optical signal. A wavelength of the reflected optical signal may be spread based on a strain being applied to the structure. A replication device may receive the reflected optical signal from the optical sensor and produce a plurality of optical signals. A filter may be coupled to the replication device to receive an optical signal from the plurality of optical signals and filter the received optical signal. A detector may receive the filtered …

Predicting Gas Mileage Using The T-Method, Parthiv Shah, Elizabeth A. Cudney, Vivek Jikar

Engineering Management and Systems Engineering Faculty Research & Creative Works

The T-method is a technique developed by Genichi Taguchi to calculate an overall prediction based on the signal-to-noise ratio without the use of Gram-Schmidt orthogonalization. the Taguchi methods, also known as Robust Design principles, are used for optimization through planning, conducting, and evaluating the results of experiments to determine the best levels of control factors. the primary goal of Robust Design is to minimize variance in the presence of noise factors to achieve a robust process. This paper outlines the T-method steps using a forecasting case study to calculate miles per gallon for vehicles with a univariate response to illustrate …

Taproot™ Technology: Tree Coring For Fast, Noninvasive Plume Delineations, Joel Gerard Burken, Sallie Bailey, Matt Shurtliff, Jeff Mcdermott

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

In Efforts to Evaluate the Use of Plants as a Forensic Tool for Delineating Contaminated Soil and Groundwater, a Laboratory Experiment and a Field Sampling Effort Were Undertaken. Site Assessments Are Often Costly and Inaccurate, Requiring Multiple Mobilizations to Hone in on Source Areas and Getting Accurate Estimates of Contaminant Extent and Distribution. as These Extensive Site Delineations Take Place, Valuable Time and Resources Are Lost. the Findings of This Study Show that Plants Can Be Used as a Tool to Evaluate a Variety of Subsurface Contaminants, Either in the Vadose Zone or in the Saturated Zone. in the First …

Thermal Converter Devices, Systems And Control Methods, Richard A. Flanagan, Rod E. Hosilyk, Rob Arlt, Kakkattukuzhy M. Isaac, Ronald E. Loving, David Alan Gordon

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A system is provided for reducing exhaust emissions. The system can comprise a series of chambers, an injector head, and a controller. The controller can maintain desired temperature zones and chemical environments inside the series of chambers, and the chambers and structures inside the system 10 can provide a desired travel path for the air, fuel, and untreated exhaust mixture inside.

Resilient Moduli Of Granular Base Materials Using A Modified Type 5 Gradation, David Newton Richardson, S. M. Lusher

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

The Missouri Department of Transportation (MoDOT) in collaboration with the Missouri Limestone Producers Association (MLPA) was interested in determining what effect a change in the Type 5 aggregate base gradation specification would have on the resilient modulus (Mr) of said aggregate. The proposed change would lower the minimum allowable total percentage of material passing the #4 (4.75 mm mesh) sieve from 35% to 25%, and the #30 (0.600 mm mesh) sieve from 10% to 5%. The remainder of the gradation specification would remain unchanged. The rationale for this proposed change is that some aggregate producers believe the change could help …

Quick Test For Percent Of Deleterious Material, David Newton Richardson

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

The Missouri Department of Transportation (MoDOT) is considering the replacement of its deleterious materials test method (TM-71) with test methods that are more objective. MoDOT contracted with the Missouri University of Science and Technology (Missouri S&T) to develop a system of test methods. Nine quarry/ledge samples representing seven geologic formations (four limestones and three dolomites) were supplied by MoDOT. The ledge samples represented three aggregates each for use in concrete, asphalt, and granular base. Samples with controlled contamination were also tested, bringing the total to 18. The aggregates were subjected to fifteen test methods. This data, coupled with MoDOT historical …

Resilient Moduli Of Typical Missouri Soils And Unbound Granular Base Materials, David Newton Richardson, Thomas M. Petry, Yu-Ning Louis Ge, Y. P. Han, S. M. Lusher

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

The objective of this project is to accurately determine the resilient moduli for common Missouri subgrade soils and unbound granular base materials in accordance with the AASHTO T 307 test method. The test results included moduli data from 27 common subgrade soils out of the 99 Missouri soil associations and from 5 unbound granular bases. These materials were tested at their optimum water content and at an elevated water content, which would normally occur as a worse case scenario during the life of a pavement. The five unbound granular base materials were tested at two different gradations (high and low …

Antibacterial Properties Of A Tri-Sodium Citrate Modified Glass Polyalkenoate Cement, A. W. Wren, D. Boyd, R. Thornton, J. C. Cooney, Mark R. Towler

Chemical and Biochemical Engineering Faculty Research & Creative Works

Primary deep infection following joint replacement surgery accounts for 7% of all revisions. Glass polyalkenoate cements (GPCs) have previously been shown to exhibit antibacterial properties. The present study had two objectives. The first was to determine if addition of tri-sodium citrate (TSC) to the powder phase of an Al-free GPC (0.04 SrO-0.12 CaO-0.36 ZnO-0.48 SiO2, by mole fraction) enhanced the resultant cement's antibacterial properties against three strains of bacteria that are commonly found in periprosthetic sites following total joint replacements (TJRs); namely, E. coli, B. fragilis, and S. epidermidis. Four cement sets were prepared, which contained 0 wt% TSC (control), …

Preliminary Investigation Of Novel Bone Graft Substitutes Based On Strontium-Calcium-Zinc-Silicate Glasses, D. Boyd, G. Carroll, Mark R. Towler, C. Freeman, P. Farthing, I. M. Brook

Chemical and Biochemical Engineering Faculty Research & Creative Works

Bone graft procedures typically require surgeons to harvest bone from a second site on a given patient (Autograft) before repairing a bone defect. However, this results in increased surgical time, excessive blood loss and a significant increase in pain. In this context a synthetic bone graft with excellent histocompatibility, built in antibacterial efficacy and the ability to regenerate healthy tissue in place of diseased tissue would be a significant step forward relative to current state of the art philosophies. We developed a range of calcium-strontium-zinc-silicate glass-based bone grafts and characterized their structure and physical properties, then evaluated their in vitro …

Structural Study On Ammonia Borane For Hydrogen Storage, William Joseph James, L. Jagat, Q. Cai, William B. Yelon, J. B. Yang

Chemistry Faculty Research & Creative Works

Ammonia borane (BH3NH3) is a promising hydrogen storage material because of its high gravimetric (19.6 wt.% H2) and volumetric hydrogen density with an accompanying moderate decomposition temperature. Previously reported structures determined by using x-ray and neutron diffraction on hydrides show differences in bond lengths and atomic coordination. Here, the crystal structures of fully and half deuterated ammonia borane were investigated as a function of temperature using powder neutron diffraction. the neutron diffraction patterns show a significant difference due to large difference in the scattering length of D and H. It is evident that an order-disorder phase transition occurs around 225 …

An Improved Upfc Control For Oscillation Damping, Jagannathan Sarangapani, Mariesa Crow, Jianjun Guo

Electrical and Computer Engineering Faculty Research & Creative Works

This paper proposes a new control approach for a unified power flow controller (UPFC) for power system oscillation damping. This control is simple to implement, yet is valid over a wide range of operating conditions. It is also effective in the presence of multiple modes of oscillation. The proposed control is implemented in several test systems and is compared against a traditional PI control.

Coordinated Reactive Power Control Of A Large Wind Farm And A Statcom Using Heuristic Dynamic Programming, Wei Qiao, Ronald G. Harley, Ganesh K. Venayagamoorthy

Electrical and Computer Engineering Faculty Research & Creative Works

A novel interface neurocontroller (INC) is proposed for the coordinated reactive power control between a large wind farm equipped with doubly fed induction generators (DFIGs) and a static synchronous compensator (STATCOM). The heuristic dynamic programming (HDP) technique and radial basis function neural networks (RBFNNs) are used to design this INC. It effectively reduces the level of voltage sags as well as the over-currents in the DFIG rotor circuit during grid faults, and therefore, significantly enhances the fault ride-through capability of the wind farm. The INC also acts as a coordinated external damping controller for the wind farm and the STATCOM, …

Phonon Confinement Effects In The Raman Spectrum Of Nanodiamond, Sebastian Osswald, Vadym Mochalin, Mickaël Havel, Gleb N. Yushin, Yury G. Gogotsi

Chemistry Faculty Research & Creative Works

Nanodiamonds (ND) exhibit unique properties due to their small size and high surface-to-volume ratio compared to bulk diamonds. A reduction in crystal size also affects ND Raman spectra. The confinement of optical phonons in nanocrystals (<10 nm) results in asymmetrically broadened Raman lines, which are shifted toward lower wavenumbers. The phonon confinement model (PCM) relates the observed changes in the Raman spectra to the crystal size and can be used for size characterization at the nanoscale. While the PCM was successfully applied to a variety of materials including Si and BN, results remained unsatisfactory in the case of ND. In order to improve the agreement between the predictions of the model and experimental Raman spectra of ND, effects such as crystal size distribution, lattice defects, and the energy dispersion of the phonon modes were taken into consideration and incorporated into the PCM. This work has shown that phonon wave vectors from small vibrational domains lead to a broad shoulder peak at ~1250 cm^-1, that is often observed in the Raman spectrum of ND.

The Effects Of Indian-Accented English And Need For Cognition On Message Evaluation: A Field Study, Duoc V. Nguyen

Dissertations and Theses @ UNI

Research has shown that Americans rate non-accented English speakers more favorably than accented English speakers (e.g., Cargile & Giles, 1997; Frumkin, 2007); however this is not always the case ( e.g., Cargile, 2000; Singer & Eder, 1988). Other factors may be involved when people are processing other people's messages. One motivating factor may be the extent to which people like to think, or have a high need for cognition (NCS; Cacioppo & Petty, 1982). As call center jobs continue to be outsourced to other countries such as India, it is important to ascertain how people with varying degrees of motivation …

Captivating Emotions: Sentiment And The Work Of Rhetorical Drag In Colonial And Early National Captivity Narrative, Gleidson Gouveia

Dissertations and Theses @ UNI

Captivity narrative, the American genre initiated early in the seventeenth century, tells the story of Europeans abducted by Native Americans in the New England frontier. These texts, however, do not simply tell the subjects' experiences of confinement among the Indians but reveal important relations of power, religion, and politics that took place in Early America. This work analyzes the captivity narratives of Mary Rowlandson, Mary Swarton, John Williams, Mary Jemison, and John Tanner to understand how their experiences were appropriated by third parties in order to meet religious and political ends of their respective times. Following scholars of captivity narrative …

The Impact Of An International Healthcare Mission Experience On Healthcare Professional Students At The University Of Northern Iowa, Evelyn Adom-Boateng

Dissertations and Theses @ UNI

U.S. Demographic changes have had an impact on health education, care, and promotion. The best health education, promotion, and care can be delivered by culturally sensitive health professionals. The importance of addressing the issue of culture is widely acclaimed by educators from various health disciplines. Participation in an international healthcare mission (IHM) is one means to expand cultural awareness and sensitivity. Little research exists regarding methods for preparing culturally sensitive healthcare professionals. Little published research documents the impact of an IHM experience on the preparation of healthcare professionals.

The purpose of this study was to investigate the impact of an …

The Stuff That Affects You: Fiction, Poetry, And Doggerel, Lisa D. Brodersen

Dissertations and Theses @ UNI

Inevitably writers write about the stuff that affects them. Maybe the stuff that affects them is life-altering, or in some way profound or sublime, like untimely death, divorce, or being in love. Or maybe it's the mundane stuff, like marbles, cats, crows, weeds, wind, rain, or riding a bike. This thesis includes fiction, poetry, and light verse (which I prefer to call doggerel) triggered by all of that stuff, but I've twisted and embellished it beyond the literal or whole truth, until what remains is nothing but the truth.

The Effect Of Learning Styles And Attitude On Preservice Elementary Teachers' Conceptual Understanding Of Chemistry And The Nature Of Matter In A Simulation-Based Learning Environment, Mo H. Al-Jaroudi

Dissertations and Theses @ UNI

This causal-comparative descriptive study investigated the achievement of pre-service elementary teachers taking an introductory physical science course that integrates inquiry-based instruction with computer simulations. The study was intended to explore if pre-service elementary teachers with different attitudes towards science as well as students with different learning styles would benefit differentially. Four research questions including four hypotheses were developed. The first major question consist of four specific hypothesis that addressed preservice elementary teachers' learning styles (Active/Reflective, Sensing/Intuitive, Visual/Verbal, and Sequential/Global) and their conceptual understanding of chemistry and the particulate nature of matter in a science class which use hands-on learning integrated …

An Exploratory Case Study Of Students' Perceptions Of Online Graduate Education, Hou Chun Kuong

Dissertations and Theses @ UNI

The purpose of this study was to investigate graduate students' perceptions of online education. Online learning has grown tremendously over the past several years and has made learning and teaching opportunities more available to many people throughout the world. As an increased number of higher education institutions use online education as a means of delivering courses and programs, educational researchers have been working tirelessly to uncover and delineate the factors that facilitate and enhance success in online learning. One major factor that researchers (e.g., Pérez Cereijo, 2006) have established as a predictor of success is students' perceptions of online learning. …

Taiwan's Language Curriculum And Policy: A Rhetorical Analysis Of The Dpp's Claims-Making, Yi-Hsuan Lee

Dissertations and Theses @ UNI

This case study of Taiwan's language curriculum and policy is a rhetorical analysis of the claims-making regarding changes with Taiwan's native languages and Chinese education.

To answer the research question of whether or not the Democratic Progressive Party (DPP) government claims support its language curriculum and policy changes, this study applied (a) Social problems research, and (b) Burke's dramatisim to analyze the claims. Two statements by the Taiwanese government about its educational policy, during the 2000-2008 presidencies, were analyzed along with the actual curriculum guidelines. Also, the opponents' opinions regarding the government's actions, which were represented in the newspapers, were …

Secondary Preservice Teachers' Understanding Of Euclidean Geometry, Karen Sabey

Dissertations and Theses @ UNI

The lack of mathematical understanding of elementary preservice teachers with respect to many mathematical topics has been well documented. Far fewer studies have been conducted on any content area of knowledge of secondary teachers and even less in the mathematics content area. The assumption by the general population is that mathematics majors are adequately prepared to teach the content of secondary mathematics because they major in mathematics. Mathematics educators, however, note the lack of conceptual understandings in many content areas in these mathematics teaching majors. While mathematics educators are aware of this deficiency, there is little research data at the …