Digital Commons Network^™

Coupled Electrical And Magnetic Properties In (La,Sr)Feo3-Δ, X.-D. Zhou, Qingsheng Cai, Jinbo Yang, M. S. Kim, William B. Yelon, William Joseph James, Y.-W. Shin, B. J. Scarfino, Harlan U. Anderson

Materials Science and Engineering Faculty Research & Creative Works

This article is aimed at studying the temperature dependence oxygen nonstoichiometry, magnetic moments, Fe³⁺ fraction, Néel temperature and conductivity of (La,Sr)FeO_3-δ. It is found that the magnetic properties in La_0.60 Sr_0.40 Fe_3-δ is determined by Fe³⁺ and its concentration, and the conductance is resulted from Fe⁴⁺ ions, which act as electron holes. Both of magnetic and electrical properties were directly governed by oxygen nonstoichiometry (δ). when δ=0.2, the compound has maximum Fe³⁺, the saturation magnetic moments and Néel temperature are 3.8 µB and 410 °C, both at the highest level, …

Efficiency In Steel Melting: Opportunities And Progress, Kent D. Peaslee, Semen Naumovich Lekakh, Von Richards, Jay Triplett

Materials Science and Engineering Faculty Research & Creative Works

This paper summarizes the findings from a study of melting efficiency in steel foundries and provides examples of material and energy savings from improvements in technology and melting practices. This study is based on information gathered at 19 Steel Founders Society of America member foundries and includes a combination of historical data and industrial measurements by the research team. Information and data were collected on the type of melting equipment, melting practices, energy use and ladle practices. The data was statistically analyzed using STATGRAPHICS commercial software. A multiple regression analysis allowed evaluation of the influence of the melting furnace (type, …

Neural Network -Based Nearly Optimal Hamilton-Jacobi-Bellman Solution For Affine Nonlinear Discrete-Time Systems, Jagannathan Sarangapani, Zheng Chen

Electrical and Computer Engineering Faculty Research & Creative Works

In this paper, we consider the use of nonlinear networks towards obtaining nearly optimal solutions to the control of nonlinear discrete-time systems. The method is based on least-squares successive approximation solution of the Generalized Hamilton-Jacobi-Bellman (HJB) equation. Since successive approximation using the GHJB has not been applied for nonlinear discrete-time systems, the proposed recursive method solves the GHJB equation in discrete-time on a well-defined region of attraction. The definition of GHJB, Pre-Hamiltonian function, HJB equation and method of updating the control function for the affine nonlinear discrete time systems are proposed. A neural network is used to approximate the GHJB …

Neural Network-Based Control Of Nonlinear Discrete-Time Systems In Non-Strict Form, Jagannathan Sarangapani, Zheng Chen, Pingan He

Electrical and Computer Engineering Faculty Research & Creative Works

A novel reinforcement learning-based adaptive neural network (NN) controller, also referred as the adaptive-critic NN controller, is developed to deliver a desired tracking performance for a class of non-strict feedback nonlinear discrete-time systems in the presence of bounded and unknown disturbances. The adaptive critic NN controller architecture includes a critic NN and two action NNs. The critic NN approximates certain strategic utility function whereas the action neural networks are used to minimize both the strategic utility function and the unknown dynamics estimation errors. The NN weights are tuned online so as to minimize certain performance index. By using gradient descent-based …

Neural Networks Based Non-Uniform Scalar Quantizer Design With Particle Swarm Optimization, Wenwei Zha, Ganesh K. Venayagamoorthy

Electrical and Computer Engineering Faculty Research & Creative Works

Quantization is a crucial link in the process of digital speech communication. Non-uniform quantizer such as the logarithm quantizers are commonly used in practice. In this paper, a companding non-uniform quantizer is designed using two neural networks to perform the nonlinear transformation. Particle swarm optimization is applied to find the weights of neural networks such that the signal to noise ratio (SNR) is maximized. Simulation results on different speech samples are presented and the proposed quantizer design is compared with the logarithm quantizer for bit rates ranging from 3 to 8.

Study Of The Electronic Structure Of Cafeo₃, Jinbo Yang, M. S. Kim, Qingsheng Cai, X.-D. Zhou, Harlan U. Anderson, William Joseph James, William B. Yelon

Materials Science and Engineering Faculty Research & Creative Works

We have studied the charge disproportionation phenomenon in CaFeO3 using the local-spin density approximation with the on-site Coulomb interaction parameter U and exchange parameter J. The calculation reveals that the total number of the 3d electrons is about 5.1 for both Fe(1)(Fe5+) and Fe(2)(Fe3+) atoms, and that there are about 0.25 electron holes in the O-2p band. Therefore, the charge disproportionation can be more accurately described as 2d5L(Fe4+)=d5L2(Fe5+)+d5(Fe3+), where L denotes a hole in the oxygen 2p band, instead of 2d4(Fe4+)=d3(Fe5+)+d5(Fe3+). The hybridization between the Fe-3d and O-2p orbitals is stronger for Fe(1) than for Fe(2) due to the shorter …

Structure, Magnetic, And Transport Properties Of Ti-Substituted La₀.₇Sr₀.₃Mno₃, M. S. Kim, Jinbo Yang, Qingsheng Cai, X.-D. Zhou, William Joseph James, William B. Yelon, D. Buddhikot, Satish K. Malik, Paul Ernest Parris

Materials Science and Engineering Faculty Research & Creative Works

Ti-substituted perovskites La_0.7Sr_0.3Mn_1-xTi_xO₃ with 0 ≤ x ≤ 0.20, were investigated by neutron diffraction, magnetization, electric resistivity, and magnetoresistance (MR) measurements. All samples show a rhombohedral structure (space group R3c) from 10 K to room temperature. At room temperature, the cell parameters a,c and the unit cell volume increase with increasing Ti content. However, at 10 K, the cell parameter a has a maximum value for x = 0.10, and decreases for x > 0.10, while the unit cell volume remains nearly constant for x > 0.10. The average (Mn,Ti)-O bond length increases …

Optimal Dynamic Neurocontrol Of A Gate-Controlled Series Capacitor In A Multi-Machine Power System, Swakshar Ray, Ganesh K. Venayagamoorthy, Edson H. Watanabe, F. D. De Jesus

Electrical and Computer Engineering Faculty Research & Creative Works

This paper presents the design of an optimal dynamic neurocontroller for a new type of FACTS device - the gate controlled series capacitor (GCSC) incorporated in a multi-machine power system. The optimal neurocontroller is developed based on the heuristic dynamic programming (HDP) approach. In addition, a dynamic identifier/model and controller structure using the recurrent neural network trained with backpropagation through time (BPTT) is employed. Simulation results are presented to show the effectiveness of the dynamic neurocontroller and its performance is compared with that of the conventional PI controller under small and large disturbances.

Aggregate Gradation Optimization -- Literature Search, David Newton Richardson

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

No abstract provided.

Engineered Struvite Precipitation: Impacts Of Component-Ion Molar Ratios And Ph, Jun Wang, Joel Gerard Burken, Xiaoqi Zhang, Rao Y. Surampalli

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Struvite precipitation has the potential for removing and recovering phosphorus from agricultural wastewater streams, such as concentrated animal feeding operations wastewater. However, impacts of anticipated component-ion molar ratios and potentially interfering ions are unknown as are the compounding pH relationship with respect to all potential complexes. This research experimentally investigates and mathematically models these factors. Emphasis is placed upon the composition of formed deposits and model validation with experimental data. Results show that calcium is a major interfering ion affecting the deposit composition, decreasing struvite purity. X-ray diffraction (XRD) and scanning electron microscopy + energy dispersive spectrometry were used to …

Spatial Bioaccumulation Modeling In A Network Of Bayous, Ronaldo Luna, Karen H. Watanabe, Andrew J. Wilding

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

A software system, Spatial Network Bioaccumulation Model (SNBM), was developed to model the bioaccumulation of polycyclic aromatic hydrocarbons (PAHs) in aquatic food webs. The SNBM uses a geographic information system as an engine to: (i) store the spatial representation of input parameters (the data related to the ecosystem), (ii) transfer input and output data to and from the food-web bioaccumulation model, and (iii) display the predicted food-web organism concentrations over a base map of the field site. The bioaccumulation model is a time-dependent, set of first-order ordinary differential equations that are solved numerically. Many sampling locations can be analyzed using …

The Influence Of Ammonia And Carbon Dioxide On The Sorption Of A Basic Organic Pollutant To A Mineral Surface, Maneerat Ongwandee, Glenn Morrison, S. S. Bettinger

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Indoor surfaces have a sorptive capacity for organic pollutants which may be significantly influenced by other gases and the pH of the surface. in this research, we examine the influence of a common indoor gaseous acid, CO₂, and base, NH₃, on the adsorption of a volatile organic base, trimethylamine (TMA), to a mineral surface, zirconium silicate beads. Varying ammonia and CO₂ within concentration ranges of indoor relevance substantially influences the sorptive capacity of this mineral surface. Increasing the CO₂ mixing ratio to 1000 p.p.m. enhances surface capacity of TMA by 40-50%; increasing the NH3 …

Modal Perturbation Method For The Dynamic Characteristics Of Timoshenko Beams, Meng-Lin Lou, Quihua Duan, Genda Chen

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Timoshenko beams have been widely used in structural and mechanical systems. under dynamic loading, the analytical solution of a Timoshenko beam is often difficult to obtain due to the complexity involved in the equation of motion. In this paper, a modal perturbation method is introduced to approximately determine the dynamic characteristics of a Timoshenko beam. In this approach, the differential equation of motion describing the dynamic behavior of the Timoshenko beam can be transformed into a set of nonlinear algebraic equations. Therefore, the solution process can be simplified significantly for the Timoshenko beam with arbitrary boundaries. Several examples are given …

An Efficient Method For Supporting Multiple Types Of Services On Smart Server, Chang-Soo Kim, Yu-Hyeon Bak, Seung-Joe Bae, Jin-Mee Kim, Sang-Min Woo, Seung-Hyup Jeon, Won-Jae Lee, Hag-Young Kim

Electrical and Computer Engineering Faculty Research & Creative Works

No abstract provided.

Decentralized Discrete-Time Neural Network Controller For A Class Of Nonlinear Systems With Unknown Interconnections, Jagannathan Sarangapani

Electrical and Computer Engineering Faculty Research & Creative Works

A novel decentralized neural network (NN) controller in discrete-time is designed for a class of uncertain nonlinear discrete-time systems with unknown interconnections. Neural networks are used to approximate both the uncertain dynamics of the nonlinear systems and the unknown interconnections. Only local signals are needed for the decentralized controller design and the stability of the overall system can be guaranteed using the Lyapunov analysis. Further, controller redesign for the original subsystems is not required when additional subsystems are appended. Simulation results demonstrate the effectiveness of the proposed controller. The NN does not require an offline learning phase and the weights …

Derivation Of A Closed-Form Approximate Expression For The Self-Capacitance Of A Printed Circuit Board Trace, Todd H. Hubing, Hwan-Woo Shim

Electrical and Computer Engineering Faculty Research & Creative Works

The electric fields that couple traces on printed circuit boards to attached cables can generate common-mode currents that result in significant radiated emissions. Previous work has shown that these radiated emissions can be estimated based on the self-capacitances of the microstrip structures on a board . In general, the determination of these self-capacitances must be done numerically using three-dimensional static modeling software. In this paper, an approximate closed-form expression for the self-capacitance of microstrip traces is derived. This expression can be used to estimate the voltage-driven common-mode emissions from boards with various microstrip trace geometries. The expression also provides insight …

Two Separate Continually Online-Trained Neurocontrollers For A Unified Power Flow Controller, Ganesh K. Venayagamoorthy, Radha P. Kalyani

Electrical and Computer Engineering Faculty Research & Creative Works

The crucial factor affecting the modern power systems today is load flow control. The Unified Power Flow Controller (UPFC) provides an effective means for controlling the power flow and improving the transient stability in a power network. The UPFC has fast complex dynamics and its conventional control is based on a linearized model of the power system. This paper presents the design of neurocontrollers to provide better damping during transient and dynamic control. Two separate neurocontrollers are used for controlling the UPFC, one neurocontroller for the shunt inverter and the other for the series inverter. Simulation studies carried out in …

Using A Neural Network To Distinguish Between The Contributions To Harmonic Pollution Of Non-Linear Loads And The Rest Of The Power System, Joy Mazumdar, Frank C. Lambert, Ganesh K. Venayagamoorthy, Ronald G. Harley

Electrical and Computer Engineering Faculty Research & Creative Works

No abstract provided.

Combining High Conductivity With Complete Optical Transparency: A Band Structure Approach, Julia E. Medvedeva, Arthur J. Freeman

Physics Faculty Research & Creative Works

A comparison of the structural, optical and electronic properties of the recently discovered transparent conducting oxide (TCO), nanoporous Ca12Al14O33, with those of the conventional TCOs (such as Sc-doped CdO) indicates that this material belongs conceptually to a new class of transparent conductors. For this class of materials, we formulate criteria for the successful combination of high electrical conductivity with complete transparency in the visible range and emphasize the significant correlation between their structural characteristics and electronic and optical properties. Our analysis suggests that this set of requirements can be met for a group of novel materials called electrides which may …

A Qualitative Investigation Of Student Interactions In A Learning Activity Center: Defining Success, At-Risk Factors, And Resiliency For Developmental Programs In Community Colleges, John L. Kalkwarf

Dissertations and Theses @ UNI

This purposive study selected ten students of different background in order to understand how the educational success of adults was affected by Learning Activity Centers (LAC) in a community college. The ten selected students were all non-traditional students who had at least these three at-risk factors: (a) they scored below the college minimums on a diagnostic test in reading, writing, or mathematics, (b) they were below student financial aid guidelines, and (c) they had an interrupted educational history of two or more years. The ten students were paired into five categories: (a) Sudanese males, (b) Mexican females, (c) single parent …

The Efficacy Of Writing Course Placement At An Iowa Community College, Kristine D. Owens

Dissertations and Theses @ UNI

The purpose of this study was to investigate the efficacy of writing course placement at an Iowa community college. The following questions were addressed: What indicators, separately or in combination, resulted in an appropriate or inappropriate student writing placement? (a) To what extent did the COMPASS test result in an appropriate placement? (b) To what extent did the self-directed essay result in an appropriate placement? (c) To what extent did a student's preference result in an appropriate placement?

This study was important to understand how the “directed self-placement” model, adapted from Royer and Gilles (1998, p. 1), impacted the institution's …

The Mind Is The Tabernacle Of The Consciousness Soul: A Journey Visiting The Roles Of Consciousness, Communication, Education, And Technology In Human And Curriculum Development By Integrating Dewey, Gebser, And Steiner: Past, Present, Future, Daniel Joseph Kazim Bardy

Dissertations and Theses @ UNI

This descriptive philosophical study examines 355+ question seeds of thought and discourse on consciousness, communication, education, and technology, much in the contexts of philosophical structures of human beings from 4,000,000 B.C. hominid man to the future of humankind and genetic enhancement. Curriculum and consciousness discussion of American John Dewey (1859–1952), Polish-born Jean Gebser (1905–1975), and Austrian-born Rudolf Steiner (1865–1920) is interwoven, finding commonalities of these philosophers and that of Daniel J. K. Bardy. Language being developed only 50,000 years ago is the defining point for Homo sapiens as the tool of linguistic communication, mutated forward much like the protrusion development …

Teacher Perceptions Of Cross-Cultural Adaptability And Instructional Practices In International Locations, Debra S. Lee

Dissertations and Theses @ UNI

The purpose of the study was to investigate differences in cross-cultural effectiveness between classroom teachers in international settings and classroom teachers in Iowa, and to examine, within a multicultural education framework, instructional practices of international teachers.

It is well documented that in American schools today, classrooms are becoming more diverse in regard to socio-economic status, ethnicity, race, intellectual ability, language, and religious heritage. School children today represent an incredibly diverse population. Conversely, the teacher population continues to be primarily female, White and from a monocultural background. This creates a mismatch between student and teacher backgrounds, perspectives, and cultural understanding, which …

The Impact Of The No Child Left Behind (Nclb) Legislation On School Leadership Of Two School Buildings Designated In Need Of Improvement: An Agency Theory Perspective, Susan Pecinovsky

Dissertations and Theses @ UNI

The purpose of conducting this study was to describe and analyze how NCLB has influenced school leaders in school buildings designated in need of assistance (SINA) and to the sanctions that accompany that label. Included in this study is the examination of the principal-agent interactions proposed in agency theory through the relationship of Iowa school leadership and the Iowa Department of Education.

From the 11 school buildings presently designated schools in need of assistance according to the Reauthorization of the Elementary and Secondary Education Act 2001 or No Child Left Behind, the school leadership of two school buildings participated in …

The Chinese Approach To Electronic Transactions Legislation, Zhang Chu, Lingfei Lei

Computer Law Review and Technology Journal

Ecclesiastes reminds us that there is nothing new under the sun, and this may be equally true when it comes to electronic transactions. In the electronic world, agreements are still embodied in contracts, contracts are still entered into when two parties reach an enforceable agreement on terms, and objective evidence still determines whether an agreement has been reached. Fraud and piracy are no less illegal because they happen online. In other words, laws governing the physical world are also relevant in the virtual world. Nevertheless, despite all the similarities, there may still be some differences in form, and there are …

Site-Specific Art Parks On Moral Ground: Distilling Old Whine In New Battles Over The Visual Artists Rights Act, Carrie Jones

Computer Law Review and Technology Journal

Having passed by unanimous vote at the Second Continental Congress, the new Constitution duly declared that "Congress shall have the power [t]o promote the Progress of Science and the useful Arts, by securing for limited Times to Authors rt]he exclusive Right to their respective Writings and Discoveries." Pursuant to that power, Congress enacted the Nation's first copyright law in 1790, intending to promote the artistic progress through a grant of exclusive monopoly for a limited time to the authors of new works. Since then, the United States has successfully urged invention and creation through the full commitment to a comprehensive …

Predictive Congestion Control Mac Protocol For Wireless Sensor Networks, Maciej Jan Zawodniok, Jagannathan Sarangapani

Electrical and Computer Engineering Faculty Research & Creative Works

Available congestion control schemes, for example transport control protocol (TCP), when applied to wireless networks results in a large number of packet drops, unfairness with a significant amount of wasted energy due to retransmissions. To fully utilize the hop by hop feedback information, a suite of novel, decentralized, predictive congestion control schemes are proposed for wireless sensor networks in concert with distributed power control (DPC). Besides providing energy efficient solution, embedded channel estimator in DPC predicts the channel quality. By using the channel quality and node queue utilizations, the onset of network congestion is predicted and congestion control is initiated. …

Reactive Power And Voltage Control Of The Nigerian Grid System Using Micro-Genetic Algorithm, Ganesh K. Venayagamoorthy, G. A. Bakare, U. O. Aliyu

Electrical and Computer Engineering Faculty Research & Creative Works

In this paper, a micro-genetic based approach to the optimization of reactive power and voltage profiles improvement and real power loss minimization is presented. The reactive power control devices such as generators, tap positions of on-load tap changer of transformers, shunt reactors are used to correct voltage limits violations while simultaneously reducing the system real power losses. Genetic algorithms (GAs) are well-known global search techniques anchored on the mechanisms of natural selection and genetics. Because of the time intensive nature of the conventional GA, the micro-GA is proposed as a more time efficient alternative. The feasibility and effectiveness of the …

Spin-System Radio-Frequency Superradiation: A Phenomenological Study And Comparison With Numeric Simulations, Carrie L. Davis, Victor K. Henner, Aleksandr V. Chernatynskiy, Ilia V. Kaganov

Physics Faculty Research & Creative Works

We discuss the coherent behavior of a polarized, nuclear or electron, spin system for which the magnetic dipole radiation emitted in the radio-frequency region, has approximately quadratic dependence on the number of spins. An effective method of describing these phenomena is provided by computer simulation of a microscopic model of the spin system. Important aspects of this numeric simulation are described, together with a comparison with the theoretical predictions. The behavior of the transverse component of the magnetic moment, M⁺ (t), in super-radiant conditions is studied. In addition, the role of dipole-dipole interactions in super-radiation phenomena is investigated in …

The Relationship Between Hypergender Ideology And Rape Empathy Among Male And Female College Students, Erin E. Okun, Suzaime L. Osman

Modern Psychological Studies

The primary purpose of the present study was to examine the relationship between hypergender ideology and rape empathy. A sample of 157 college students completed a questionnaire packet containing demographic variables, the Hypergender Ideology Scale (HOS) and the Rape Empathy Scale (RES). It was predicted that those indicating stronger adherence to extreme stereotypic gender roles would report more empathy for the perpetrator rather than the victim of rape. It was also predicted that men would show stronger adherence to stereotypic gender roles and less victim empathy than women. Results show significant support for all predictions. Discussion involves implications that the …