Engineering Commons^™

Designing A Multimedia Learning Environment That Engages Children Through Narrative, Glenn W. Ellis, Al Rudnitsky, Beth Mcginnis-Cavanaugh, Isabel Huff, Sonia K. Ellis

Engineering: Faculty Publications

This paper examines the use of Imaginative Education for designing an online learning environment for middle school engineering education. In Imaginative Education, cognitive tools associated with the development of linguistic ability are used to engage learners and frame their learning productively. The Through My Window website applies a variety of cognitive tools related to mythic and romantic understanding through the use of an online novel and interactive learning adventures associated with the novel. The focus of this paper is an AI learning adventure on the website titled Rio's Brain. It was found, through embedded assessment within the learning adventure, that …

Inn Nems And Heterojunction Devices For Sensing Applications, Alina Wilson

Theses and Dissertations

Recent research trends in chemical and biological sensing have been geared toward developing molecular sensor devices that are fast, inexpensive, miniaturized, have low power consumption and are portable. The performance of these devices can be dramatically improved by utilizing multimodal detection techniques, new materials and nanofabrication technologies. To develop such sensor devices, we utilized Indium Nitride (InN) nanowires (NWs) to fabricate nanoelectromechanical system (NEMS) based sensors and Graphene/InN NW heterojunctions, and InN thin films to fabricate Graphene/InN thin film heterojunction based sensors. InN NWs, which exhibit interesting properties including high carrier density, superior electron mobility, strong surface charge accumulation, and …

Stargrazer One: A New Architecture For Distributed Maximum Power Point Tracking Of Solar Photovoltaic Sources, Edgard Munoz-Coreas

Theses and Dissertations--Electrical and Computer Engineering

The yield from a solar photovoltaic (PV) source is dependent on factors such as light and temperature. A control system called a maximum power point tracker (MPPT) ensures that the yield from a solar PV source is maximized in spite of these factors. This thesis presents a novel implementation of a perturb and observe (PO) MPPT.

The implementation uses a switched capacitor step down converter and a custom digital circuit implementation of the PO algorithm. Working in tandem, the switched capacitor step down converter and the custom digital circuit implementation were able to successfully track the maximum power point of …

Nanostructured Semiconductor Device Design In Solar Cells, Hongmei Dang

Theses and Dissertations--Electrical and Computer Engineering

We demonstrate the use of embedded CdS nanowires in improving spectral transmission loss and the low mechanical and electrical robustness of planar CdS window layer and thus enhancing the quantum efficiency and the reliability of the CdS-CdTe solar cells. CdS nanowire window layer enables light transmission gain at 300nm-550nm. A nearly ideal spectral response of quantum efficiency at a wide spectrum range provides an evidence for improving light transmission in the window layer and enhancing absorption and carrier generation in absorber. Nanowire CdS/CdTe solar cells with Cu/graphite/silver paste as back contacts, on SnO₂/ITO-soda lime glass substrates, yield the …

Constrained Divergence-Conforming Basis Functions For Method Of Moments Discretizations In Electromagnetics, Robert Pfeiffer

Theses and Dissertations--Electrical and Computer Engineering

Higher-order basis functions are widely used to model currents and fields in numerical simulations of electromagnetics problems because of the greater accuracy and computational efficiency they can provide. Different problem formulations, such as method of moments (MoM) and the finite element method (FEM) require different constraints on basis functions for optimal performance, such as normal or tangential continuity between cells. In this thesis, a method of automatically generating bases that satisfy the desired basis constraints is applied to a MoM formulation for scattering problems using surface integral equations. Numerical results demonstrate the accuracy of this approach, and show good system …

Explorations For Efficient Reversible Barrel Shifters And Their Mappings In Qca Nanocomputing, Ke Chen

Theses and Dissertations--Electrical and Computer Engineering

This thesis is based on promising computing paradigm of reversible logic which generates unique outputs out of the inputs and. Reversible logic circuits maintain one-to-one mapping inside of the inputs and the outputs. Compared to the traditional irreversible computation, reversible logic circuit has the advantage that it successfully avoids the information loss during computations. Also, reversible logic is useful to design ultra-low-power nanocomputing circuits, circuits for quantum computing, and the nanocircuits that are testable in nature. Reversible computing circuits require the ancilla inputs and the garbage outputs. Ancilla input is the constant input in reversible circuits. Garbage output is the …

Multifrequency Averaging Of Hysteresis-Current-Controlled Dc-Dc Converters, Yingying Liu

Theses and Dissertations--Electrical and Computer Engineering

Multifrequency averaging is one of the widely used modeling and simulation techniques today for the analysis and design of power electronic systems. This technique is capable of providing the average behavior as well as the ripple behavior of power electronic systems. Hysteresis current control has fast response and internal current stability through controlling switches to maintain the current within a given hysteresis band of a given current command. However the state space variables in a hysteresis controlled system cannot be directly approached by multifrequency averaging method because of time varing switching frequency. In this thesis, a method of applying multifrequency …

A New Islanding Detection Method Based On Wavelet-Transform And Ann For Inverter Assisted Distributed Generator, Zhengyuan Guan

Theses and Dissertations--Electrical and Computer Engineering

Nowadays islanding has become a big issue with the increasing use of distributed generators in power system. In order to effectively detect islanding after DG disconnects from main source, author first studied two passive islanding methods in this thesis: THD&VU method and wavelet-transform method. Compared with other passive methods, each of them has small non-detection zone, but both of them are based on the threshold limit, which is very hard to set. What’s more, when these two methods were applied to practical signals distorted with noise, they performed worse than anticipated.

Thus, a new composite intelligent based method is presented …

The Constrained Locally Corrected Nyström Method, Nastaran Hendijani

Theses and Dissertations--Electrical and Computer Engineering

In this dissertation a generalization of the locally corrected Nyström (LCN) discretization method is outlined wherein sparse transformations of the LCN system matrix are obtained via singular value decompositions of local constraint matrices. The local constraint matrices are used to impose normal continuity of the currents across boundaries shared by mesh elements. For this reason, the method is called constrained LCN (CLCN).

Due to the CLCN’s simplicity and flexibility, it is straightforward to develop high order CLCN systems for different formulations and mesh element types. As compared to the LCN, the CLCN method offers memory savings and improved accuracy when …

Average-Value Modeling Of Hysteresis Current Control In Power Electronics, Hanling Chen

Theses and Dissertations--Electrical and Computer Engineering

Hysteresis current control has been widely used in power electronics with the advantages of fast dynamic response under parameter, line and load variation and ensured stability. However, a main disadvantage of hysteresis current control is the uncertain and varying switching frequency which makes it difficult to form an average-value model. The changing switching frequency and unspecified switching duty cycle make conventional average-value models based on PWM control difficult to apply directly to converters that are controlled by hysteresis current control.

In this work, a new method for average-value modeling of hysteresis current control in boost converters, three-phase inverters, and brushless …

Compensation Methods For Demand Response, Zhaofeng Wang

Theses and Dissertations--Electrical and Computer Engineering

Recently, more and more disputations about how demand response should be compensated have arisen. Moreover, the court is about to rehear the Order 745. It probably will have significant impact on the whole working system used to be built for demand response before. Nowadays, some power companies and utilities think that they will endure profits leakage while demand response resources still are compensated.

In this research, knowledge of demand response, local marginal price, Order 745 and other related concept will be explained in detail in case of misunderstanding. Associated with all these knowledge, a possible compensation method will be proposed. …

Browser Based Visualization For Parameter Spaces Of Big Data Using Client-Server Model, Kurtis M. Glendenning

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Visualization is an important task in data analytics, as it allows researchers to view abstract patterns within the data instead of reading through extensive raw data. Allowing the ability to interact with the visualizations is an essential aspect since it provides the ability to intuitively explore data to find meaning and patterns more efficiently. Interactivity, however, becomes progressively more difficult as the size of the dataset increases. This project begins by leveraging existing web-based data visualization technologies and extends their functionality through the use of parallel processing. This methodology utilizes state-of-the-art techniques, such as Node.js, to split the visualization rendering …

Surface Treatments To Tailor The Wettability Of Carbon Nanotube Arrays, Lvmeng He

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Carbon nanotubes (CNTs) have gained great attention due to their excellent mechanical, electrical, and thermal properties. Carbon nanotube (CNT) arrays attached to solid substrates resemble a nano-carpet and have potentials in a variety of devices. In this study, the focus is to investigate the surface modification approaches of CNT carpets on flat (compressed) graphite. Wettability, or permeation of a liquid such as water into the CNT strands, may play very significant roles in many applications where a CNT-coated device may be used in aqueous environment. Short-term microwave plasma treatments were used in this project to functionalize CNT carpets for wettability. …

A Framework For Uncertainty Quantification In Microstructural Characterization With Application To Additive Manufacturing Of Ti-6al-4v, Gregory Thomas Loughnane

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The sampling of three dimensional (3D) mesoscale microstructural data is typically prescribed using simple rules, likely resulting in data under- or oversampling depending on the measurement(s) of interest. The first part of this work investigates one approach for determining a minimally sufficient sampling scheme for 3D microstructural data, using computer-generated phantoms of polycrystalline grain microstructures. Sources of error that are observed experimentally are modeled using phantoms, in order to determine the effect that errors have on the microstructural statistic(s)-of-interest. Minimally-sufficient sampling schemes are then established based on a required accuracy in the microstructural statistic(s). The characterization error modeling framework is …

Nano-Materials For Microwave And Terahertz Applications, Joshua Myers

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In this age of digital electronics the quest for faster computational devices and high speed communications have driven a need for new materials that are capable of fulfilling these goals. In both areas the need for a thinner channel in transistors, faster carrier transport characteristics, and better magnetic materials dominate the direction of research. Recently 2D materials have been realized. These single layer atomic thick materials show potential in having extremely high carrier transport velocities at room temperature and, due to their natural 2D structure, are the thinnest material possible in nature. On the other hand spin-spray ferrites have showed …

Owl Query Answering Using Machine Learning, Todd Huster

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The formal semantics of the Web Ontology Language (OWL) enables automated reasoning over OWL knowledge bases, which in turn can be used for a variety of purposes including knowledge base development, querying and management. Automated reasoning is usually done by means of deductive (proof-theoretic) algorithms which are either provably sound and complete or employ approximate methods to trade some correctness for improved efficiency. As has been argued elsewhere, however, reasoning methods for the Semantic Web do not necessarily have to be based on deductive methods, and approximate reasoning using statistical or machine-learning approaches may bring improved speed while maintaining high …

Temporally Biased Search Result Snippets, J. Abhiram Tatineni

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The search engine result snippets are an important source of information for the user to obtain quick insights into the corresponding result documents. When the search terms are too general, like a person's name or a company's name, creating an appropriate snippet that effectively summarizes the document's content can be challenging owing to multiple occurrences of the search term in the top ranked documents, without a simple means to select a subset of sentences containing them to form result snippet. In web pages classified as narratives and news articles, multiple references to explicit, implicit and relative temporal expressions can be …

A Reconfigurable Spice-Based Cmos Lna Design In 90 Nm Technology Using Ads Rfic Dynamic Link, Pushpak Vasanth Rayudu Arja

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In this thesis, a reconfigurable dual band CMOS LNA with a switching-type circuit topology is proposed. The reconfigurable dual-band LNA can be tuned to operating fre- quency of either 1.575 GHz for global positioning system (GPS) or 2.4GHz for WLAN 802.11b standards. The simulated results performed power gain of 11.2 dB and 12.4 dB, noise figure of 3.4 dB and 2.9 dB, input return loss(S11) of -25.26 dB and-21.4 dB, third- order input intercept point of -3.12 dBm and -2.137 dBm and the design dissipates 8.9 mW and 4.68 mW of power at 1.2 V power supply at the two …

High Frequency Resolution Adaptive Thresholding Wideband Receiver System, Feiran Liu

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Fast Fourier transformation (FFT) is widely used in wideband digital receivers to detect multiple signals. To achieve high dynamic range, the receiver has to increase analog-to-digital (ADC) resolution bits, which requires significant computation time and therefore increases receiver time resolution. The other challenge of FFT approach is two signals with a small frequency difference (i.e., less than five FFT frequency bins in most cases) cannot be detected simultaneous. This thesis presents an adaptive thresholding wideband digital receiver to accurately detect two simultaneous high dynamic range signals even when they are close to one FFT frequency bin. The receiver can perform …

Wide Tuning Range I/Q Dco Vco And A High Resolution Pfd Implementation In Cmos 90 Nm Technology, Eswar Raju Suraparaju

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This thesis presents wide tuning range in-phase and quad-phase (I/Q) output digital control oscillator (DCO) and voltage control oscillator (VCO) and a simple high performance phase frequency detector (PFD) in 90 nm CMOS technology with 1.2 V power supply. The designed I/Q output DCO has an operating frequency range from 1.1-8.2 GHz with high resolution and wide linearity by using a novel skew delay structure. At 2.02GHz oscillation frequency, the measured phase noise of I/Q output DCO is -90.43dBc/Hz at an offset of 1 MHz offset and has 5 mW of power dissipation. A complementary series coupled quadrature VCO (S-QVCO) …

Design Of A Novel Low - Cost, Portable, 3d Ultrasound System With Extended Imaging Capabilities For Point-Of-Care Applications, Michail Tsakalakis

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Ultrasound Imaging (USI) or Medical Sonography (MS), as it is formally called, has been widely used in biomedical applications over the last decades. USI can provide clinicians with a thorough view of the internal parts of the human body, making use of sound waves of higher frequencies than humans can perceive. USI systems are considered highly portable and of low-cost, compared to other imaging modalities. However, despite those advantages, Ultrasound Systems (US) and especially 3D ones, have not been yet extensively utilized for Point-of-Care (POC) applications, due to numerous restrictions and artifacts that they currently present.

Hardware complexity and real-time …

Mathematical Models And Solution Approach For Staff Scheduling With Cross-Training At Call Centers, Taskiran, Gamze Kilincli

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Call centers face demand that varies throughout the week across multiple service categories and typically employ non-standard workforce schedules to meet this demand. In call centers, cross-training provides a buffer against fluctuation of demand between categories and is widely used. Full cross-training, however, is financially impractical in most cases, which has created a challenging problem in how to optimize a cross-trained workforce, i.e., a) what categories should be cross-trained, b) what portion of the workforce should be cross-trained, and c) how to schedule their weekly assignments. This problem is motivated by the need of a Fortune 50 company's technology support …

Mining Behavior Of Citizen Sensor Communities To Improve Cooperation With Organizational Actors, Hemant Purohit

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Web 2.0 (social media) provides a natural platform for dynamic emergence of citizen (as) sensor communities, where the citizens generate content for sharing information and engaging in discussions. Such a citizen sensor community (CSC) has stated or implied goals that are helpful in the work of formal organizations, such as an emergency management unit, for prioritizing their response needs. This research addresses questions related to design of a cooperative system of organizations and citizens in CSC. Prior research by social scientists in a limited offline and online environment has provided a foundation for research on cooperative behavior challenges, including 'articulation' …

Verification And Validation Of A Transient Heat Exchanger Model, Jayme Lee Carper

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A statistical based verification and validation process is applied to the transient modeling of a shell and tube heat exchanger. A generic model of a heat exchanger was developed based on first principles as a sub-system of a larger thermal system model. This model was originally created without any experimental data, as it was not readily available. To provide the data necessary to apply the validation process, a thermal emulator was designed and built that allowed control of all system inputs to the heat exchanger, while also providing the instrumentation to record all required data. A wide test matrix was …

Tunable Absorption Based On Plasmonic Nanostructures Loaded With Graphene, Christos Argyropoulos

Department of Electrical and Computer Engineering: Faculty Publications

We present simulations of a hybrid graphene-plasmonic device constituted by periodic metallic nanowires placed over a dielectric spacer layer and a metallic film. The spacer layer is composed of a thin silica layer combined with an one-atom-thick graphene sheet. An electrically controlled ultra-compact absorption modulator can be realized based on the proposed theoretical device.

Robust Optimization For Bidirectional Dispatch Coordination Of Large-Scale V2g, Xiaoqing Bai, Wei Qiao

Department of Electrical and Computer Engineering: Faculty Publications

This paper proposes a robust optimization (RO) model for bidirectional dispatch coordination of large-scale plugin electric vehicles (PEVs) in a power grid in which the PEVs are aggregated to manage. The PEV aggregators are considered as a type of dispatchable demand response and energy storage resource with stochastic behaviors, and can supply load or provide ancillary services such as regulation reserve to the grid. The proposed RO model is then reformulated as a mixedinteger quadratic programming model, which can be solved efficiently. Computer simulations are performed for a power grid with ten generators and three PEV aggregators to validate the …

Optimal Bidding Strategy Of A Strategic Wind Power Producer In The Short-Term Market, Ting Dai, Wei Qiao

Department of Electrical and Computer Engineering: Faculty Publications

Wind energy is a clean and renewable energy source which is rapidly growing globally. As the penetration level of wind power grows, the system operators need to consider wind power producers as strategic producers whose bidding behaviors will have an impact on the locational marginal prices. This paper proposes a bilevel stochastic optimization model to obtain the optimal bidding strategy for a strategic wind power producer in the short-term electricity market. The upper level problem of the model maximizes the profit of the wind power producer, while the lower level problem represents the market clearing processes of both day-ahead and …

Multiobjective Optimization Of Switched Reluctance Motors Based On Design Of Experiments And Particle Swarm Optimization, Cong Ma, Liyan Qu

Department of Electrical and Computer Engineering: Faculty Publications

This paper proposes a comprehensive framework for multiobjective design optimization of switched reluctance motors (SRMs) based on a combination of the design of experiments and particle swarm optimization (PSO) approaches. First, the definitive screening design was employed to perform sensitivity analyses to identify significant design variables without bias of interaction effects between design variables. Next, optimal third-order response surface (RS) models were constructed based on the Audze–Eglais Latin hypercube design using the selected significant design variables. The constructed optimal RS models consist of only significant regression terms, which were selected by using PSO. Then, a PSO-based multiobjective optimization coupled with …

A Survey On Wind Turbine Condition Monitoring And Fault Diagnosis−Part I: Components And Subsystems, Deli Qiao, Dingguo Lu

Department of Electrical and Computer Engineering: Faculty Publications

This paper provides a comprehensive survey on the state-of-the-art condition monitoring and fault diagnostic technologies for wind turbines. The Part I of this survey briefly reviews the existing literature surveys on the subject, discusses the common failure modes in the major wind turbine components and subsystems, briefly reviews the condition monitoring and fault diagnostic techniques for these components and subsystems, and specifically discusses the issues of condition monitoring and fault diagnosis for offshore wind turbines.

A Survey On Wind Turbine Condition Monitoring And Fault Diagnosis−Part Ii: Signals And Signal Processing Methods, Wei Qiao, Dingguo Lu

Department of Electrical and Computer Engineering: Faculty Publications

This paper provides a comprehensive survey on the state-of-the-art condition monitoring and fault diagnostic technologies for wind turbines. The Part II of this survey focuses on the signals and signal processing methods used for wind turbine condition monitoring and fault diagnosis.