Engineering Commons^™

Decentralized Multi-Agent Reinforcement Learning In Average-Reward Dynamic Dcops, Duc Thien Nguyen, William Yeoh, Hoong Chuin Lau, Shlomo Zilberstein

Research Collection School Of Computing and Information Systems

Researchers have introduced the Dynamic Distributed Constraint Optimization Problem (Dynamic DCOP) formulation to model dynamically changing multi-agent coordination problems, where a dynamic DCOP is a sequence of (static canonical) DCOPs, each partially different from the DCOP preceding it. Existing work typically assumes that the problem in each time step is decoupled from the problems in other time steps, which might not hold in some applications. Therefore, in this paper, we make the following contributions: (i) We introduce a new model, called Markovian Dynamic DCOPs (MD-DCOPs), where the DCOP in the next time step is a function of the value assignments …

On Understanding Diffusion Dynamics Of Patrons At A Theme Park, Jiali Du, Akshat Kumar, Pradeep Reddy Varakantham

Research Collection School Of Computing and Information Systems

In this work, we focus on the novel application of learning the diffusion dynamics of visitors among attractions at a large theme park using only aggregate information about waiting times at attractions. Main contributions include formulating optimisation models to compute diffusion dynamics. We also developed algorithm capable of dealing with noise in the data to populate parameters in the optimization model. We validated our approach using cross validation on a real theme park data set. Our approach provides an accuracy of about 80$% for popular attractions, providing solid empirical support for our diffusion models.

Nonlinear Weir Hydraulics, Mitchell R. Dabling

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

A hydraulically undersized control structure (i.e., an emergency dam spillway) could result in water overtopping a dam or riverbanks. To increase hydraulic capacity and reduce flooding risk, nonlinear weirs are being used to replace undersized linear weirs during control structure rehabilitation. The complex geometry of a nonlinear weir creates an infinite number of designs and three-dimensional flow patterns. This study investigates four subjects to further knowledge on two types of nonlinear weir, the piano key and labyrinth.

Weir submergence is a condition when the downstream water level of a weir exceeds the weir crest elevation, and can influence the head-discharge …

Robotic Resistance/Assistance Training Improves Locomotor Function In Individuals Poststroke: A Randomized Controlled Study, Ming Wu, Jill M. Landry, Janis Kim, Brian D. Schmit, Sheng-Che Yen, Jillian Macdonald

Biomedical Engineering Faculty Research and Publications

Objective

To determine whether providing a controlled resistance versus assistance to the paretic leg at the ankle during treadmill training will improve walking function in individuals poststroke.

Design

Repeated assessment of the same patients with parallel design and randomized controlled study between 2 groups.

Setting

Research units of rehabilitation hospitals.

Participants

Patients (N=30) with chronic stroke.

Intervention

Subjects were stratified based on self-selected walking speed and were randomly assigned to the resistance or assistance training group. For the resistance group, a controlled resistance load was applied to the paretic leg at the ankle to resist leg swing during treadmill walking. …

Fabrication And Characterization Of Amorphous/Nanocrystalline Thin Film Composite, Benjamin Seth Newton

Graduate Theses and Dissertations

Combining the absorption abilities of amorphous silicon and the electron transport capabilities of crystalline silicon would be a great advantage to not only solar cells but other semiconductor devices. In this work composite films were created using molecular beam epitaxy and electron beam deposition interchangeably as a method to create metallic precursors. Aluminum induced crystallization techniques were used to convert an amorphous silicon film with a capping layer of aluminum nanodots into a film composed of a mixture of amorphous silicon and nanocrystalline silicon. This layer was grown into the amorphous layer by cannibalizing a portion of the amorphous silicon …

Fabrication Of Single Nanowire Device Using Electron Beam Lithography, Thach Pham

Graduate Theses and Dissertations

One dimensional nanostructure materials such as nanowires have drawn many interests among the scientific community for a wide range of applications such as field-effect transistors [1], [2], inverters[3], light-emitting diode [1], lasers [4], nanosensors [5], [6], and photodetectors [7]... Comparing with the characterization of nanowire arrays, characterizing a single nanowire will definitely provide a better understanding on new nanowire properties due to simplified behaviors of devices. Although promising theories could be drawn from those results, fabrication of test structure for single nanowire measurements cannot be easily processed using standard microfabrication techniques. Therefore, electron beam lithography integrated with photolithography technique has …

Radiation-Hardened Delay-Insensitive Asynchronous Circuits For Multi-Bit Seu Mitigation And Data-Retaining Sel Protection, John Davis Brady

Graduate Theses and Dissertations

Radiation can have highly damaging effects on circuitry, especially for space applications, if designed without radiation-hardening mechanisms. Delay-insensitive asynchronous circuits inherently have promising potentials in mitigating the effects of radiation due to their delay insensitivity. This thesis proposes the use of two delay-insensitive asynchronous logic architectures to mitigate the effects of up to two single-event upsets (SEU) and a single-event latch-up (SEL). The multi-bit SEU mitigation with SEL protection architecture improves the original design by providing more integrity against data corruption and lock-ups caused by multi-bit SEUs, and it is expanded to simultaneously provide protection against SEL. The multi-bit SEU …

Discrete Strain Engineering In Graphene, Cedric Marcus Horvath

Graduate Theses and Dissertations

Graphene has a number of fascinating mechanical and electrical properties. Strain engineering in graphene is the attempt to control its properties with mechanical strain. Previous research in this area has come up with an approach using a continuum theory to describe the strain induced gauge fields in graphene; however, this approach is only valid for small strains (5% at most). A discrete framework is being developed in Arkansas that can more accurately calculate the deformation (electrical) and (pseudo-)magnetic gauge fields created by large strains. Computational simulations were carried out and used to get discrete atomic positions for strained, suspended graphene …

Synthesis And Characterization Of Nanocrystals And Their Application For Photodetectors, Ahmad Nusir

Graduate Theses and Dissertations

Room temperature operation is considered one of the essential restrictions in the design of electronic devices. Photodetectors are unable to detect light efficiently at room temperature due to high dark currents. Semiconductor nanocrystals possess unique optical and electrical properties which make them ideal for fabricating uncooled photodetectors. In this project, nanocrystals were synthesized and implemented in devices that detect light at room temperature.

Nanocrystalline I-III-VI2 and II-VI semiconductors (CuInS2 and CdSe) were grown by a wet chemical method, and characterized using: optical absorption, photoluminescence, Raman scattering, and x-ray diffraction. The optical absorption and photoluminescence spectra of the nanocrystals were recorded …

Broadband Nanostructured Antireflection Coating For Enhancing Inas/Gaas Quantum Dots Solar Cells Performance, Jony C. Sarker

Graduate Theses and Dissertations

The broadband suppression in reflection is one of the primary focuses in high efficiency solar cell research. In this thesis, a moth-eye inspired nanostructure antireflection coating is fabricated on InAs/GaAs quantum dots solar cell in order to enhance the power conversion efficiency. The abrupt refractive index transition between air and GaAs surface is replaced by a tapering zinc oxide nanoneedle on planar tantalum pentoxide coating. The antireflection structure provides gradual reduction of refractive index away from the solar cell top surface.

The nanostructured antireflection coating is fabricated by utilizing chemical bath deposition of tapered zinc oxide nanoneedles on planar tantalum …

Faculty Internships For Capstone Design Instructors: Maintaining An Up-To-Date Capstone Design Course, Jay R. Goldberg

Biomedical Engineering Faculty Research and Publications

No abstract provided.

Parasitic Layer-Based Reconfigurable Antenna And Array For Wireless Applications, Zhouyuan Li

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Antenna is one of the most important components in wireless systems since signal transmission and reception are conducted through the antenna interface. Therefore, the signal quality is highly affected by the properties of the antenna. Traditional antennas integrated in devices such as laptops or cell phones have fixed radiation properties and can not be changed to adapt to different environments. Thus the performance of thefwhole system will be negatively affected since the antenna will not operate in the optimum status in different environments. To solve this problem, reconfigurable antenna, which can dynamically change its operation frequency, radiation pattern, and polarization, …

Comparison Of Selected Differential Producing, Ultrasonic, And Magnetic Flow Meters, Johnny B. Prettyman

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Flow meters are used to measure flow accurately. There are many different flow meters and it is necessary to know which will function best for specific situations. A wide variety of flow meters were selected for the study to assist in showing that each flow meter has its tradeoffs. The selected meters include: three types of Venturi meters, a wedge meter, a V-cone meter, an electromagnetic flow meter, and an ultrasonic flow meter. The characteristics researched in this study are discharge coefficient (Cd) over a range of Reynolds numbers (Re), head loss across each flow meter, life, and cost of …

A Sociocultural Analysis Of Latino High School Students' Funds Of Knowledge And Implications For Culturally Responsive Engineering Education, Joel Alejandro Mejia

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Previous studies have suggested that, when funds of knowledge are incorporated into science and mathematics curricula, students are more engaged and often develop richer understandings of scientific concepts. While there has been a growing body of research addressing how teachers may integrate students’ linguistic, social, and cultural practices with science and mathematics instruction, very little research has been conducted on how the same can be accomplished with Latino and Latina students in engineering. The purpose of this study was to address this gap in the literature by investigating how fourteen Latino and Latina high school adolescents used their funds of …

Resolving The Temporal-Spatial Ambiguity With The Auroral Spatial Structures Probe, Daniel Farr

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The behavior of the electric and magnetic fields in the upper atmosphere of the Earth is scientifically interesting but difficult to study, since balloons and aircraft are unable to fly high enough to measure it directly. Sounding rockets, which make a one-time flight carrying instruments that measure the environment around them, have been successfully used to study the upper atmosphere. As the rocket flies through the upper atmosphere, it radios down data about the environment. When scientists on the ground use this data to construct a picture of the upper atmosphere, they run into a problem: the fields reported by …

The Design And Testing Of A Three-Degree-Of-Freedom Small Satellite Simulator Using A Linear Controller With Feedback Linearization And Trajectory Generation, Marina A. Samuels

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

A small satellite simulator with attitude determination and control was designed and implemented in hardware. The simulator consists of inertial sensors for attitude determination and a pyramidal four-wheel momentum exchange system as the control actuators. A linearized PV controller with trajectory generation and feedback linearization was implemented, with the focus on controlling yaw. The simulator was tested on a spherical air bearing platform to allow three-degree-of-freedom operation. The simulator software was developed to read measurements from the sensors, apply the control algorithm, and send commands to the actuators. A data processing routine was developed. Electromechanical testing for the system as …

Humanity Hyper-Externalized, Josh Gloe

Honors Capstones

Capstone submitted as a graduation requirement for the BSU Honors Program.

Probability Distributions And Threshold Selection For Monte Carlo–Type Tropical Cyclone Wind Speed Forecasts, Steven M. Lazarus, Michael E. Splitt, Sarah Collins, Denis N. Botambekov, William P. Roeder

Aeronautics Faculty Publications

Probabilistic wind speed forecasts for tropical cyclones from Monte Carlo–type simulations are assessed within a theoretical framework for a simple unbiased Gaussian system that is based on feature size and location error that mimic tropical cyclone wind fields. Aspects of the wind speed probability data distribution, including maximumexpected probability and forecast skill, are assessed. Wind speed probability distributions are shown to be well approximated by a bounded power-law distribution when the feature size is smaller than the location error and tends toward a U-shaped distribution as the location error becomes small. Forecast skill (i.e., true and Heidke skill scores) is …

Anisotropy Of The Reynolds Stress Tensor In The Wakes Of Counter-Rotating Wind Turbine Arrays, Nicholas Michael Hamilton

Dissertations and Theses

A wind turbine array was constructed in the wind tunnel at Portland State University in a standard Cartesian arrangement. Configurations of the turbine array were tested with rotor blades set to rotate in either a clockwise or counter-clockwise sense. Measurements of velocity were made with stereo particle-image velocimetry. Mean statistics of velocities and Reynolds stresses clearly show the effect of direction of rotation of rotor blades for both entrance and exit row turbines. Rotational sense of the turbine blades is visible in the mean spanwise velocity W and the Reynolds shear stress -[macron over vw]. The normalized anisotropy tensor was …

Nanowire Zinc Oxide Mosfet Pressure Sensor, William Clavijo

Theses and Dissertations

Fabrication and characterization of a new kind of pressure sensor using self-assembly Zinc Oxide (ZnO) nanowires on top of the gate of a Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET) is presented. Self-assembly ZnO nanowires were fabricated with a diameter of 80 nm and 800 nm height (80:8 aspect ratio) on top of the gate of the MOSFET. The sensor showed a 110% response in the drain current due to pressure, even with the expected piezoresistive response of the silicon device removed from the measurement. The pressure sensor was fabricated through low temperature bottom up ultrahigh aspect ratio ZnO nanowire growth using anodic …

Dynamic Task-Allocation For Unmanned Aircraft Systems, Tim Bakker

Theses and Dissertations

This dissertation addresses improvements to a consensus based task allocation algorithms for improving the Quality of Service in multi-task and multi-agent environments. Research in the past has led to many centralized task allocation algorithms where a central computation unit is calculating the global optimum task allocation solution. The centralized algorithms are plagued by creating a single point of failure and the bandwidth needed for creating consistent and accurate situational awareness off all agents. This work will extend upon a widely researched decentralized task assignment algorithm based on the consensus principle. Although many extensions have led to improvements of the original …

Polarization-Coupled Ferroelectric Unpolarunction Memory And Energy Storage Device, Mathias M. Schubert, Tino Hofmann, Venkata Rao Voora

Department of Electrical and Computer Engineering: Faculty Publications

A memory device is provided. The memory device includes a plurality of memory cells and a controller to write data to and read data from the memory cells. Each memory cell includes a first semiconductor material having a spontaneous polarization, a resistive ferroelectric material having a switchable spontaneous polarization, and a second semiconductor material having a spontaneous polarization, the resistive ferroelectric material being positioned between and in contact with the first and second semiconductor materials. The memory device can be configured to store energy that can be released by applying a voltage pulse to the memory device.

In Vitro Immersion Behavior Of Cold Sprayed Hydroxyapatite/Titanium Composite Coatings, Lin Lu, Xuan Joe Zhou, Pravansu Mohanty

Electrical & Computer Engineering Publications

In previous study, dense and homogenous 20wt% HAP/Ti composite coatings were successfully deposited on Ti substrates by cold gas dynamic spray technique. The results revealed that the phase composition of the HAP in the deposit is identical to that of the precursor powder and the bonding strength of the deposit is comparable/better to that of the plasma sprayed HAP. A relatively higher corrosion current of HAP/Ti composite than that of pure Ti coating in simulated body fluid indicates a good bioactivity for composite coating. In the present study, in vitro immersion test is carried out for various period of time …

Dynamic Modelling Of Impact Of Lean Policies On Production Levelling Feasibility, Hoda Elmaraghy, Ahmed Deif

Industrial Technology and Packaging

A dynamic systems approach is proposed to investigate challenges of implementing production leveling and associated costs. A model of a lean cell is developed using system dynamics. The model captures various lean tools influencing production leveling. Comparative cost analysis between various leveling implementation policies for stochastic demand with multiple products is conducted. Results showed that determining the most feasible leveling policy is highly dictated by both capacity scalability cost and limitations. The developed model and revealed insights can help lean practitioners to better decide on when and how to implement production leveling as well as determine production lots sizes.

Cti White Paper, Tim Brady, Gregory Mcguirk

Publications

The FAA Air Traffic Collegiate Training Initiative (AT-CTI) Program has 36 partner institutions across the United States which offer a variety of accredited academic degrees and actively promote a multicultural and diverse collegiate environment.

Preparation And Electrochemical Performances Of Cofe2O4/Gns Nanocomposites As Anode Material For Lithium Ion Battery, Mo-Chao Cai, Sen-Rong Cai, Ming-Sen Zheng, Quan-Feng Dong

Journal of Electrochemistry

The CoFe₂O₄/GNS was synthesized by a simple one-pot solvothermal method. The results obtained by X-ray diffraction (XRD) and transmission electron microscopy (TEM) showed that the CoFe₂O₄ particles with sizes of 15 nm dispersed on the surface of graphene uniformly. Electrochemical tests indicated that the CoFe₂O₄/GNS nanocomposite exhibited excellent cyclic stability with almost 95.8% capacity retention after 100 cycles at the current density of 500 mA·g^-1 and delivered a high reversible capacity of 482 mAh·g^-1 at the current density of 2 A·g^-1.

A Sinteractive Ni-Bazr0.8Y0.2O3-Δ Composite Membrane For Hydrogen Separation, Shumin Fang, Siwei Wang, Kyle S. Brinkman, Fanglin Chen

Faculty Publications

BaZr_0.8Y_0.2O_3−δ (BZY) is an excellent candidate material for hydrogen permeation membranes due to its high bulk proton conductivity, mechanical robustness, and chemical stability in H₂O- and CO₂-containing environments. Unfortunately, the use of BZY as a separation membrane has been greatly restrained by its highly refractory nature, poor grain boundary proton conductivity, high number of grain boundaries resulting from limited grain growth during sintering, as well as low electronic conductivity. These problems can be resolved by the fabrication of a Ni–BZY composite membrane with large BZY grains, which requires the development …

Design Of A Small Form-Factor Flight Control System, Garrett Ward

Theses and Dissertations

This work outlines a design for a small form-factor flight control system designed to fly in a wide variety of airframes. The system was designed with future expansion in mind while providing a complete, all-in-one solution to meet present needs. This system as presented meets most needs while remaining relatively low cost. It has a completely integrated IMU solution as well as on- board GPS. It is capable of basic waypoint navigation. This solution was testing using software and hardware-in-the-loop simulation which proved its functionality.

In Situ Detection On Electrochemical Chloride Removal Of Reinforcement In Concrete By Combined Ph/Cl- Probes, Jing-Jing Wang, Shi-Gang Dong, Xiao-Juan Zhang, Hong-Wei Lv, Yun-Chang Wu, Rong-Gui Du, Chang-Jian Lin

Journal of Electrochemistry

In this work, the concrete samples polluted by chloride ion were electrochemically treated using galvanostatic technique, and the distributions of chloride ion concentration and pH value in the polluted concretes were in-situ monitored by embedding a combined pH/Cl^- probe during the electrochemical chloride removal. The corrosion behaviors of reinforcing steel in the concrete were simultaneously studied by using linear polarization and electrochemical impedance spectroscopy techniques (EIS). The micro environment of the concrete and corrosion rate of steel were explored during the electrochemical chloride removal. It was indicated that the Cl^- concentration in the concrete pore solution decreased with …

Electro-Catalytic Oxidation Of Hydrogen Peroxide On Au/ L-Methionine /Gc Electrode, Jian-Feng Fan, Xue-Mei Luo, Jing Li, Lou-Zhen Fan

Journal of Electrochemistry

The modified electrodes have been fabricated by generation of Au nanoparticle chains, which was produced by reaction between HAuCl4 and sodium citrate without any additional capping agents or surfactants. The self-assembled Au nanoparticles were attached to the surface of glassy carbon electrode (GCE) layer by layer, using L-methionine (L-Met), thiourea (TU), allyl thiourea (ATU) and polyvinylpyrrolidone (PVP) as a crosslinking agent, respectively. The experimental results showed that the electrochemical performance of the different modified electrodes varied in [Fe(CN)₆]^3-/4- solution. The Au/L-Met/GCE exhibited an excellent electrochemical property, which is superior to other modified electrodes. In addition, the catalysis …