Digital Commons Network^™

Sharpening The Blunt Blue Pencil: Renewing The Reasons For Covenants Not To Compete In North Carolina, Jon J. Lee, Kimberly Burke

Faculty Articles

Covenants not to compete are often included in modern employment contracts to prevent employees from working for competitors for a specified amount of time after termination of employment. Although such covenants were initially unenforceable at common law because they represented invalid restraints on trade, most jurisdictions today enforce covenants not to compete where such covenants are reasonable. Jurisdictions differ, however, in their treatment of unreasonable covenants, choosing from one of three approaches: the all-or nothing approach, which prohibits a court from striking out or modifying any part of a covenant; the "strict blue pencil doctrine," which allows a court to …

Citizen Participation In Japanese Criminal Trials: Reimagining The Right To Trial By Jury In The United States, Jon J. Lee

Faculty Articles

If the United States were to reform contemporary jury trials to match the Founders’ conception of the right to trial by jury, how might they look? In recent years, we have gained insight into how to answer that question from an unlikely source: Japan. This Article examines the introduction of citizen participation into the Japanese judicial system (the saiban-in seido) from a different perspective. Rather than focusing on the contemporary American jury system, this Article evaluates the Japanese reforms in light of the Founders’ conception of the right to trial by jury. It is this conception of the right to …

Computationally Efficient Finite Element Models Of The Lumbar Spine For The Evaluation Of Spine Mechanics And Device Performance, Sean D. Smith

Electronic Theses and Dissertations

Finite Element models of the lumbar spine are commonly used for the study of spine mechanics and device performance, but have limited usefulness in some applications such as clinical and design phase assessments due to long analysis times. In this study a computationally efficient L4-L5 FSU model and a L1-Sacrum multi-segment model were developed and validated. The FSU is a functional spine unit consisting of two adjacent vertebral bodies, in this case L4 and L5. The multi-segment model consists of all lumbar vertebrae and the sacrum. The models are able to accurately predict spine kinematics with significantly reduced analysis times, …

The Effect Of Atmospheric Aging On A Hybrid Polymer Matrix Composites' Material Properties, Brian Michael Burks

Electronic Theses and Dissertations

Mechanical failure modes associated with elevated temperature exposure of the load bearing unidirectional hybrid composite (based upon glass and carbon fibers reinforcing a high temperature epoxy matrix) of a next generation transmission line design were investigated in this research. In particular, the flexural performance (in both static and fatigue loading) of the composite which had been exposed to elevated temperatures for prolonged periods of time was studied. To this end, a fatigue test was developed in an attempt to simulate the multi-axial loading conditions present on transmission lines. This test was used to evaluate the fatigue behavior of unaged specimens, …

Growth Diagram And Magnetic Properties Of Hexagonal Lufe2o4 Thin Films, Wenbin Wang, Zheng Gai, Miaofang Chi, Jason D. Fowlkes, Jieyu Yi, Leyi Zhu, Xuemei Cheng, David J. Keavney, Paul C. Snijders, Thomas Z. Ward, Jian Shen, Xiaoshan Xu

Xiaoshan Xu Papers

Agrowth diagram of Lu-Fe-O compounds on MgO (111) substrates using pulsed laser deposition is constructed based on extensive growth experiments. The LuFe₂O₄ phase can only be grown in a small range of temperature and O₂ pressure conditions. An understanding of the growth mechanism of Lu-Fe-O compound films is offered in terms of the thermochemistry at the surface. Superparamagnetism is observed in the LuFe₂O₄ film and is explained in terms of the effect of the impurity hexagonal LuFeO₃ (h-LuFeO₃) phase and structural defects.

Crystal Field Splitting And Optical Bandgap Of Hexagonal Lufeo3 Films, Wenbin Wang, Hongwei Wang, Xiaoying Xu, Leyi Zhu, Lixin He, Elizabeth Wills, Xuemei Cheng, David J. Keavney, Jian Shen, Xifan Wu, Xiaoshan Xu

Xiaoshan Xu Papers

Hexagonal LuFeO₃ films have been studied using x-ray absorption and optical spectroscopy. The crystal splitting of Fe³⁺ is extracted as E_e' - E_e" = 0.7 eV and E_a'1 - E_e' = 0.9 eV, and a 2.0 eV optical bandgap is determined assuming a direct gap. First-principles calculations confirm the experiments that the relative energies of crystal field splitting states do follow E_a'1 > E_e' > E_e" with slightly underestimated values and a bandgap of 1.35 eV.

The Local Metallicity Of Gadolinium Doped Compound Semiconductors, J. A. Colon Santana, Pan Liu, Xianjie Wang, J. Tang, S. R. Mchale, D. Wooten, J. W. Mcclory, J. C. Petrosky, J. Wu, R. Palai, Ya B. Losovjy, P. A. Dowben

Department of Physics and Astronomy: Faculty Publications

The local metallicities of Hf_0:97Gd_0:03O₂, Ga_0:97Gd_0:03N, Eu_0:97Gd_0:04O and EuO films were studied through a comparison of the findings from constant initial state spectroscopy using synchrotron light. Resonant enhancements, corresponding to the 4d→4f transitions of Eu and Gd, were observed in some of the valence band photoemission features. The resonant photoemission intensity enhancements for the Gd 4f photoemission features are far stronger for the more insulating host systems than for the metallic system Eu_0:96Gd_0:04O. The evidence seems to suggest a correlation between the …

Rare Earth 4f Hybridization With The Gan Valence Band, Lu Wang, Wai-Ning Mei, S. R. Mchale, J. W. Mcclory, J. C. Petrosky, J. Wu, R. Palai, Y. B. Losovyj, Peter A. Dowben

Department of Physics and Astronomy: Faculty Publications

The placement of the Gd, Er and Yb 4f states within the GaN valence band has been explored by both experiment and theory. The 4d–4f photoemission resonances for various rare-earth(RE)-doped GaN thin films (RE = Gd, Er, Yb) provide an accurate depiction of the occupied 4f state placement within the GaN. The resonant photoemission show that the major Er and Gd RE 4f weight is at about 5–6 eV below the valence band maximum, similar to the 4f weights in the valence band of many other RE-doped semiconductors. For Yb, there is a very little resonant enhancement of the valence …

Isothermal Entropy Changes In Nanocomposite Co:Ni67Cu33, Steven A. Michalski, Ralph Skomski, Xingzhong Li, Damien Le Roy, Tathagata Mukherjee, Christian Binek, David J. Sellmyer

David Sellmyer Publications

The temperature-dependent magnetic properties of artificial rare-earth, free-magnetic nanostructures are investigated for magnetic cooling. We consider two-phase nanocomposites, where 2 nm nanoclusters of cobalt are embedded in a Ni₆₇Cu₃₃ matrix. Several composite films were produced by cluster deposition. The average Co nanocluster size can be tuned by varying the deposition conditions. Isothermalmagnetization curves weremeasured at various temperatures 150K

Magnetism Of Directly Ordered Sm-Co Clusters, Balamurugan Balasubramanian, Ralph Skomski, Xingzhong Li, George C. Hadjipanayis, David J. Sellmyer

David Sellmyer Publications

Sm-Co bulk alloys have shown superior permanent-magnet properties, but research on Sm-Co nanoparticles is challenging because of the need to control particle size, size-distribution, crystalline ordering, and phase purity. In the present study, a cluster-deposition method was used to produce Sm-Co nanoparticles having desired crystal structures without the requirement of subsequent high-temperature thermal annealing. Poorly crystallized SmCo₅ nanoparticles exhibit a low room-temperature coercivity of only 100 Oe, whereas crystalline SmCo₅ and Sm₂Co₁₇ nanoparticles show room-temperature coercivities of 2000 and 750 Oe, respectively. The direct synthesis of Sm-Co nanoparticles having sizes of less than 10 nm …

Magnetism Of Dilute Co(Hf) And Co(Pt) Nanoclusters, Balamurugan Balasubramanian, Ralph Skomski, Xingzhong Li, Shah R. V, Priyanka Manchanda, Arti Kashyap, David J. Sellmyer

David Sellmyer Publications

An investigation of the magnetic properties of Co-rich nanoparticles alloyed with a small fraction of Pt and Hf is presented. Co(Hf) and Co(Pt) nanoparticles with less than 15 at% of dopants were produced using a cluster-deposition method. The nanoparticles have sizes of less than 10 nm and show improved magnetic properties upon doping. Maximum coercivities of 900 Oe (at 300 K) and 2000 Oe (at 10 K) were observed for Co nanoparticles alloyed with 14.1 at% of Hf. Doped nanoparticles also exhibit high anisotropies, such as K₁¼9.98 Mergs=cm³ (14.1 at% of Hf) and K₁¼8.24 Mergs=cm …

Aligned And Exchange-Coupled L10 (Fe,Co)Pt-Based Magnetic Films, Yi Liu, Thomas A. George, Ralph Skomski, David J. Sellmyer

David Sellmyer Publications

Films of aligned L1₀-structure (Fe,Co)Pt with fcc Fe(Co,Pt) are synthesized by co-sputtering Fe, Co, and Pt on an (001) MgO substrate with in situ heating at 830 degrees C. The nanostructures and magnetic properties of the films are characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and superconducting quantum interference device (SQUID). The compositions of the samples (Fe,Co)_xPt_1-x are designed to maintain an atomic Fe: Co ratio of 65: 35 while increasing the Fe,Co content in each successive sample. In samples with low Fe and Co concentration, the XRD patterns exhibit three strong peaks, …

Assembly Of Uniaxially Aligned Rare-Earth-Free Nanomagnets, Balamurugan Balamurugan, Bhaskar Das, Shah R. Valloppilly, Ralph Skomski, Xingzhong Li, David J. Sellmyer

David Sellmyer Publications

We report HfCo₇ nanoparticles with appreciable permanent-magnet properties (magnetocrystalline anisotropy K₁≈10 Mergs/cm³, coercivity H_c ≈ 4.4 kOe, and magnetic polarization J_s≈10.9 kG at 300 K) deposited by a single-step cluster-deposition method. The direct crystalline-ordering of nanoparticles during the gas-aggregation process, without the requirement of a high-temperature thermal annealing, provides an unique opportunity to align their easy axes uniaxially by applying a magnetic field of about 5 kOe prior to deposition, and subsequently to fabricate exchange-coupled nanocomposites having J_s as high as 16.6 kG by co-depositing soft magnetic Fe-Co. This study suggests …

Writing For The Web: Twitter As A Starting Point For Breaking News, Sue Burzynski Bullard, Michelle Carr Hassler

College of Journalism and Mass Communications: Faculty Publications

Students enrolled in a multimedia reporting course use Twitter to cover breaking news events as they unfold, capitalizing on the immediacy of the social media network and the Web. Using cellphones or laptops, they learn to tell stories 140 characters at a time. The second half of this assignment requires students to build on their Twitter stories by posting follow-up stories and photographs to a class website. The follow- ups, written within six hours of events, must include additional reporting. The assignment marries traditional writing and reporting skills with digital tools increasingly being used in the real world.

Thermal Quench Effects On Ferroelectric Domain Walls, P. Paruch, A. B. Kolton, X. Hong, C. H. Ahn, T. Giamarchi

Xia Hong Publications

Using piezoresponse force microscopy on epitaxial ferroelectric thin films, we have measured the evolution of domain wall roughening as a result of heat-quench cycles up to 735 ◦C, with the effective roughness exponent ζ changing from 0.25 to 0.5. We discuss two possible mechanisms for the observed ζ increase: a quench from a thermal one-dimensional configuration and from a locally equilibrated pinned configuration with a crossover from a two- to one-dimensional regime. We find that the postquench spatial structure of the metastable states, qualitatively consistent with the existence of a growing dynamical length scale whose ultraslow evolution is primarily controlled …

Electric Modulation Of Magnetization At The Batio3/La0.67sr0.33mno3 Interfaces, H. Lu, Thomas A. George, Yong Wang, Ihor Ketsman, John D. Burton, C.-W. Bark, Sangjin Ryu, Dong Jik Kim, J. Wang, Christian Binek, Peter A. Dowben, Andrei Sokolov, C. B. Eom, Evgeny Y. Tsymbal, Alexei Gruverman

Alexei Gruverman Publications

We report large (>10%) magnetization modulation by ferroelectric polarization reversal in the ferroelectric-ferromagnetic BaTiO₃/La_0.67Sr_0.33MnO₃ (BTO/LSMO) heterostructures. We find that the electrically induced change in magnetization is limited to the BTO/LSMO interface but extends about 3 nm deep into the LSMO layer—far beyond the expected screening length of metallic LSMO. It is suggested that this effect is due to a metal-insulator transition occurring at the BTO/LSMO interface as a result of electrostatic doping.

Tunnel Electroresistance In Junctions With Ultrathin Ferroelectric Pb(Zr0.2ti0.8)O3 Barriers, Daniel Pantel, Haidong Lu, Silvana Goetze, Peter Werner, Dong Jik Kim, Alexei Gruverman, Dietrich Hesse, Marin Alexe

Alexei Gruverman Publications

In ferroelectric tunnel junctions, the ferroelectric polarization state of the barrier influences the quantum-mechanical tunneling through the junction, resulting in tunnel electroresistance (TER). Here, we investigate tunnel electroresistance in Co/PbZr_0.2Ti_0.8O₃/La_0.7Sr_0.3MnO₃ tunnel junctions. The ferroelectric polarization in tunnel junctions with 1.2-1.6 nm (three to four unit cells) PbZr_0.2Ti_0.8O₃ thickness and an area of 0.04 μm² can be switched by about 1 V yielding a resistive ON/OFF-ratio of about 300 at 0.4 V. Combined piezoresponse force microscopy and electronic transport investigations of these junctions reveal …

Orientation Of Doubly Excited States In N2, John E. Furst, Timothy J. Gay, Joshua Machacek, David Kilkoyne, Kenneth W. Mclaughlin

Timothy J. Gay Publications

We have measured the total fluorescent intensity and circular polarization of light emitted in 3p ⁴P^o → 3s⁴P transitions of excited neutral nitrogen atoms created by the photofragmentation of the N₂ molecule with circularly polarized light having energies between 21 and 26 eV. The intensity measurements show the effect of predissociation of the N₂ Rydberg series R(C) ¹Σ⁺_u states by non-Rydberg doubly excited resonances (NRDERs), while nonzero values of circular polarization allow us to unambiguously identify the presence of a directly excited NRDER with ¹Π …

A Novel Fixed-Target Task To Determine Articulatory Speed Constraints In Persons With Amyotrophic Lateral Sclerosis, Antje Mefferd, Jordan R. Green, Gary L. Pattee

Department of Special Education and Communication Disorders: Faculty Publications

Purpose: The goal of this study was to determine if talkers with ALS are limited in their ability to increase lower lip and jaw speed at an early stage of the disease when their speaking rate and intelligibility are only minimally or not affected.

Method: A novel metronome paced fixed-target task was used to assess movement speed capacities during lower lip and jaw oscillations in seven talkers with ALS and seven age and gender matched controls.

Results: Lower lip peak speeds were significantly lower in talkers with mild ALS than in healthy talkers suggesting a lower lip speed constraint in …

Modification Of Perioral Stiffness In Patients With Repaired Cleft Lip And Palate, Steven M. Barlow, Carroll-Ann Trotman, Shin-Ying Chu, Jaehoon Lee

Department of Special Education and Communication Disorders: Faculty Publications

Objective—To measure and compare the perioral stiffness among three groups of pediatric subjects: a group of patients with a repaired cleft lip (and palate) who had a secondary lip revision surgery (revision), another group of patients with repaired cleft lip (and palate) who did not have secondary surgery (nonrevision), and a group of noncleft “normal” patients (noncleft).

Design—A parallel, three-group, nonrandomized clinical trial.

Participants—A total of 16 patients with repaired cleft lip/palate who did not have lip revision, 13 patients with repaired cleft lip/palate who had lip revision surgery and were tested at 18 to 24 months postsurgery, and 27 …

Imbalance Fault Detection Of Direct-Drive Wind Turbines Using Generator Current Signals, Xiang Gong, Wei Qiao

Department of Electrical and Computer Engineering: Faculty Publications

Imbalance faults constitute a significant portion of all faults in wind turbine generators (WTGs). WTG imbalance fault detection using generator current measurements has advantages over traditional vibration-based methods in terms of cost, implementation, and system reliability. However, there are challenges in using current signals for imbalance fault detection due to low signal-to-noise ratio of the useful information in current signals and non-stationary characteristic frequencies of imbalance faults. This paper proposes a method of using generator stator currents for imbalance fault detection of direct-drive WTGs. In the proposed method, the variable shaft rotating frequency of a WTG is estimated from one …

Power Semiconductor Devices, Jerry Hudgins, Rik W. De Doncker

Department of Electrical and Computer Engineering: Faculty Publications

Historically, Power Semiconductor devices have been divided into three broad categories: diodes, transistors, and thyristors. Although modern devices can be classified in this way, there is an increasing overlap in device design and function. Also semiconductors, such as silicon carbide (SiC), gallium nitride (GaN), and other materials, as well as novel device designs have increased the suitability and broadened the applications of semiconductor switches in megawatt (MW) power conversion circuits and systems.

Modern Transistors

Transistors include the traditional power bipolar (nonsilicon materials being considered for the future), power metal-oxide-semiconductor field-effect transistors (MOSFETs), and hybrid devices that have some aspect of …

A Series-Connected Self-Reconfigurable Multicell Battery Capable Of Safe And Effective Charging/Discharging And Balancing Operations, Taesic Kim, Wei Qiao, Liyan Qu

Department of Electrical and Computer Engineering: Faculty Publications

Bidirectional DC/DC converters are commonly used for charging and discharging multicell batteries under various modes, such as Pulsed Current (PC), Constant Current (CC), and Constant Current Constant Voltage (CCCV). The charge and discharge are usually terminated by the converters when battery voltages reach some threshold values. However, cell state imbalance is commonly present in traditional multicell batteries, which reduces the available capacities of the batteries in certain charge/discharge cycles and shortens the life cycles of the batteries. To solve this problem, this paper proposes a series-connected, self-reconfigurable, multicell battery with a bidirectional DC/DC converter capable of safe and effective charging, …

Analysis Of Π-Phase-Shifted Fiber Bragg Gratings For Ultrasonic Detection, Tongqing Liu, Ming Han

Department of Electrical and Computer Engineering: Faculty Publications

Using numerical simulations, we investigated the responses of the π-phase-shifted fiber Bragg gratings (πFBGs) impinged by pressure ultrasonic waves. The effect of the grating length, grating refractive index modification depth, and ultrasonic frequency on the wavelength sensitivity and intensity sensitivity of the πFBG ultrasonic sensor for ultrasonic waves of different wavelengths was analyzed. The directivity of a πFBG sensor was also studied. Our analysis revealed several unique πFBG response characteristics and will be useful in the design and optimization of fiber-optic ultrasonic sensors that use a πFBG as the sensing element.

Real-Time Stereo Matching On Cuda Using An Iterative Refinement Method For Adaptive Support-Weight Correspondences, Jedrzej Kowalczuk, Eric T. Psota, Lance C. Pérez

Department of Electrical and Computer Engineering: Faculty Publications

High-quality real-time stereo matching has the potential to enable various computer vision applications including semi-automated robotic surgery, tele-immersion, and three-dimensional video surveillance. A novel real-time stereo matching method is presented that uses a two-pass approximation of adaptive support-weight aggregation, and a low-complexity iterative disparity refinement technique. Through an evaluation of computationally efficient approaches to adaptive support weight cost aggregation, it is shown that the two-pass method produces an accurate approximation of the support weights while greatly reducing the complexity of aggregation. The refinement technique, constructed using a probabilistic framework, incorporates an additive term into matching cost minimization and facilitates iterative …

Optical Properties Of Cobalt Slanted Columnar Thin Films Passivated By Atomic Layer Deposition, Daniel Schmidt, Eva Schubert, Mathias Schubert

Department of Electrical and Computer Engineering: Faculty Publications

Optical properties of passivated metal slanted columnar thin films from cobalt within the visible spectral region are reported. Glancing angle deposition is utilized to grow slanted nano-columns which have been conformally coated with Al₂O₃ by a subsequent atomic layer deposition process. A generalized anisotropic Bruggeman effective medium approximation has been employed to analyze spectroscopic generalized ellipsometry data. The modified homogenization approach allows for determination of biaxial (monoclinic) optical and structural properties as well as fractions of three film constituents. The conformal alumina passivation layer preserves the pristine metal character of the nano-structures and prevents oxidation and aging …

Position Extraction From A Discrete Sliding-Mode Observer For Sensorless Control Of Ipmsms, Yue Zhao, Wei Qiao, Long Wu

Department of Electrical and Computer Engineering: Faculty Publications

Sliding-mode observers (SMOs) offer a promising solution for sensorless control of interior permanent magnet synchronous machines (IPMSMs) due to their excellent robustness to system structure and parameter uncertainty. However, in practical applications, it is challenging for an SMO to achieve a perfect estimation for the back electromagnetic force (EMF) using a finite or relatively lower sampling frequency, especially for high-speed applications. Phase shift, magnitude variation, and heavy noise in the estimated back EMF will cause unexpected errors in rotor position extraction. Thus, advanced rotor position extraction methods are needed to obtain position information from the estimated back EMF. This paper …

Compensation Algorithms For Sliding Mode Observers In Sensorless Control Of Ipmsms, Yue Zhao, Wei Qiao, Long Wu

Department of Electrical and Computer Engineering: Faculty Publications

Electromechanical sensors are commonly used to obtain rotor position/speed for high-performance control of interior permanent magnet synchronous machines (IPMSMs) in vehicle systems. However, the use of these sensors increases the cost, size, weight, wiring complexity and reduces the mechanical robustness of IPMSM drive systems. These issues, together with some practical requirements, e.g., wide speed range, extreme environment temperature, and adverse loading conditions, make a sensorless control scheme desirable. This paper proposes an extended back electromotive force (EMF)-based sliding mode rotor position observer for sensorless vector control of IPMSMs. Based on filter characteristics, a robust compensation algorithm is developed to improve …

Adaptation Of Reduction Indices To North American Assemblages: Developing A Methodology For The Investigation Of The Quarry Creek Assemblages, Ft. Leavenworth, Kansas, Eric Skov

Nebraska Anthropologist

Reduction measures, especially those measures which compute a scaled index, have been profitably employed in archaeological research on many Old World assemblages. Utilization of these techniques is still a burgeoning subject in North American archaeology, however, and North American assemblages present unique challenges to the analyst. Chief among these difficulties are the greater prevalence of hafted bifaces and other formal tools, especially when contrasted to the Mousterian toolkits that have been the traditional targets for reduction analyses. Other researchers have developed new methods for analyzing projectile points or end scrapers, though these methods are not without weaknesses and I am …

Developing An Electronic Repository For Undergraduate Theses, Foster Levy, Rebecca Pyles, Celia Szarejko, Linda Wyatt

Honors in Practice Online Archive

Undergraduate honors theses represent an intellectual asset that a university should recognize and manage as such. However, when theses were submitted exclusively in print copies, the work often faded into obscurity, forgotten by all but the student and mentor. While theses for advanced degrees have been accessible for many years via interlibrary loan or abstract services, similar access options have been unavailable for undergraduate theses because these works are most often associated with and maintained by the institutional honors program without involvement or support from the institution’s library system. At best, an index of undergraduate theses might be available to …