Engineering Commons^™

The Santa Clara, 2013-02-14, Santa Clara University

The Santa Clara

No abstract provided.

Interfacial Thermal Conductance Limit And Thermal Rectification Across Vertical Carbon Nanotube/Graphene Nanoribbon-Silicon Interfaces, Ajit K. Vallabhaneni, Bo Qiu, Jiuning Hu, Yong P. Chen, Ajit K. Roy, Xiulin Ruan

Birck and NCN Publications

Various models were previously used to predict interfacial thermal conductance of vertical carbon nanotube (CNT)-silicon interfaces, but the predicted values were several orders of magnitude off the experimental data. In this work, we show that the CNT filling fraction (the ratio of contact area to the surface area of the substrate) is the key to remedy this discrepancy. Using molecular dynamics, we have identified an upper limit of thermal interface conductance for C-Si interface which is around 1.25GW/m(2)K, corresponding to a 100% filling fraction of carbon nanotube or graphene nanoribbon on substrate. By extrapolating to low filling fraction (similar to …

Influenza Forecasting With Google Flu Trends, Andrea Freyer Dugas, Mehdi Jalalpour, Yulia Gel, Scott Levin, Fred Torcaso, Takeru Igusa, Richard E. Rothman

Civil and Environmental Engineering Faculty Publications

Background: We developed a practical influenza forecast model based on real-time, geographically focused, and easy to access data, designed to provide individual medical centers with advanced warning of the expected number of influenza cases, thus allowing for sufficient time to implement interventions. Secondly, we evaluated the effects of incorporating a real-time influenza surveillance system, Google Flu Trends, and meteorological and temporal information on forecast accuracy.

Methods: Forecast models designed to predict one week in advance were developed from weekly counts of confirmed influenza cases over seven seasons (2004–2011) divided into seven training and out-of-sample verification sets. Forecasting procedures …

Carbothermal Synthesis Of Titanium Oxycarbide As Electrocatalyst Support With High Oxygen Evolution Reaction Activity, Kan Huang, Yunfeng Li, Yangchuan Xing

Chemical and Biochemical Engineering Faculty Research & Creative Works

Carbothermal reduction of semiconducting TiO₂ into highly conductive titanium oxycarbide (TiOxCy) was investigated. The thermally produced uniform carbon layer on TiO₂ (Degussa P25) protects the TiO₂ nanoparticles from sintering and, at the same time, supplies the carbon source for doping TiO₂ with carbon. At low temperatures (e.g., 700 °C), carbon only substitutes part of the oxide and distorts the TiO₂ lattice to form TiO₂-xCx with only substitutional carbon. When the carbon-doped TiO₂ is annealed at a higher temperature (1100 °C), x-ray diffraction and x-ray photoelectron spectroscopy results showed that TiOxCy, a solid …

Vtt Technical Research Centre Of Finland, Vtt Technical Research Centre

Robert "Bob" Twiggs STEM Education Collection

A PowerPoint Presentation titled "VTT Technical Research Centre of Finland" from February 14, 2013.

Covariance Modeling And Space-Time Coding For Mimo Systems, Farnaz Karimdady Sharifabad

Theses and Dissertations

The full spatial covariance matrix of the multiple input multiple-output (MIMO) channel is an important quantity in channel modeling, communication system signal processing, and performance analysis, and therefore this matrix forms the heart of the research outlined in this dissertation. The work begins with an investigation of a generalized framework for computing the full MIMO spatial covariance based on the power angular spectrum (PAS) of the multipath field and the transmit and receive antenna element radiation patterns. For the case of uniform linear arrays and when the PAS clusters satisfy uniform, truncated Gaussian, or truncated Laplacian distributions, a series expansion …

Material Characterization Of Ultra-High Performance Fiber Reinforced Concrete At Elevated Temperatures, Richard T. Way

Master's Theses

With the recent development of Ultra High Performance Fiber Reinforced Concrete (UHPFRC), there has been limited investigation into the mechanical and material properties of this composite at elevated temperatures. At elevated temperatures concrete is shown to undergo several material changes which affect the residual mechanical properties. Additionally, fast heating rates are known to cause a phenomenon called explosive spalling. This research investigates the effect of high temperature on the residual mechanical properties and chemical degradation of two types of UHPFRC. This was accomplished by casting and testing two different UHPFRC mixes and exposing them to elevated temperatures at two rates …

Material Characterization And The Effects Of Moisture And Drying On Injection Molded Torlon 5030, Michael R. Di Re

Master's Theses

The effects of water absorption and drying were studied on injection molded Torlon 5030, a high performance thermoplastic fabricated by Solvay Specialty Polymers. Torlon 5030 contains 30% by weight glass fibers in a polyamide-imide base resin. The objective behind this work was to test and better define relevant properties for industrial applications using this material. While the material design guide offers information on many mechanical properties including tensile, fatigue, and creep data; there is little to no publicly published data on the effects of water absorption and any subsequent drying of Torlon 5030. Blistering was also studied. With exposure to …

Compositional Tuning Of Structural Stability Of Lithiated Cubic Titania Via A Vacancy-Filling Mechanism Under High Pressure, Hui Xiong

Materials Science and Engineering Faculty Publications and Presentations

Experimental and theoretical studies on the compositional dependence of stability and compressibility in lithiated cubic titania are presented. The crystalline-to-amorphous phase transition pressure increases monotonically with Li concentration (from ∼17.5  GPa for delithiated to no phase transition for fully lithiated cubic titania up to 60 GPa). The associated enhancement in structural stability is postulated to arise from a vacancy filling mechanism in which an applied pressure drives interstitial Li ions to vacancy sites in the oxide interior. The results are of significance for understanding mechanisms of structural response of metal oxide electrode materials at high pressures as well as emerging …

College Of Engineering News, Georgia Southern University

College of Engineering & Computing: News & Publications (2010-2023)

• The Department of Information Technology Joins Linux Professional Institute’s Approved Academic Partner Program

Just-In-Time Power Gating Of Gasp Circuits, Prachi Gulab Padwal

Dissertations and Theses

In modern integrated circuits, one way to reduce power consumption is to turn off power to parts of the circuit when those are idle. This method is called power gating. This thesis presents a state-preserving technique to achieve power savings in GasP family of asynchronous circuits by turning off the power when the circuit is idle. The power control logic turns on the power in anticipation of the receiving data. The power control logic turns off the power when the stage is idle either because it is empty or because the pipeline is clogged. The low logical effort of GasP …

Picture Of A Chelate In Exchange: The Crystal Structure Of Nahodotma, A 'Semi'-Hydrated Chelate, Katherine M. Payne, Edward J. Valente, Silvio Aime, Mauro Botta, Mark Woods

Chemistry Faculty Publications and Presentations

Crystallography generally only provides static structural information. This can render it an ineffective technique for probing dynamic solution state processes. A crystal of HoDOTMA affords unique structures that effectively represent that of a lanthanide tetra-acetate chelate mid-way through the water exchange process.

Future Engineering Professors' Conceptions Of Learning And Teaching Engineering, Ana Teresa Torres Ayala

USF Tampa Graduate Theses and Dissertations

Conceptions of learning and teaching shape teaching practices and are, therefore, important to understanding how engineering professors learn to teach. There is abundant research about professors' conceptions of teaching; however, research on the conceptions of teaching of doctoral students, the future professors, is scarce. Furthermore, there is a need to understand not just future engineering professors' conceptions of teaching but also their conceptions of learning. The purpose of this study was to explore qualitative variations in future engineering professors' conceptions of learning and teaching as well as understanding how they came to these conceptions.

The research questions that guided this …

Hydraulic Evaluation Of A Community Managed Wastewater Stabilization Pond System In Bolivia, Louis Lizima

USF Tampa Graduate Theses and Dissertations

This work explores the hydraulic performance of a wastewater lagoon system located in San Antonio, Bolivia. The system consists of one facultative pond and two maturation ponds in series and is managed through a locally elected water committee. A tracer study was performed on the primary facultative pond and an analysis of the solids accumulation on the bottom of the facultative lagoon was also performed. The results were used to generate residence time distribution curves and provide an estimate of mean residence time in the system. The data was used to examine hydraulic efficiency as it relates to short-circuiting and …

Environmental And Energy Saving Technologies Of Vinyl Chloride Production, Mykola Kurta

USF Tampa Graduate Theses and Dissertations

Recently, because of the increase of environmental concerns in process design, the need to enhance conversion to product and prevent generation of wasteful byproducts in the reactor network has become urgent. This prevents high cost treatment and separation costs downstream in the process. Therefore, in this thesis I focus on making production of vinyl chloride monomer (VCM) more efficient and on possible ways of industrial organochlorine waste (OCW) recycling. In particular, in the first experiment, we investigate how catalyst and its structure can affect product output.

Infrared spectroscopy and X-ray diffraction analysis were utilized to investigate the structure of the …

Location And Capacity Modeling Of Network Interchanges, Aldo D. Fabregas

USF Tampa Graduate Theses and Dissertations

Network design decisions, especially those pertaining to urban infrastructure, are made by a central authority or network leader, and taking into consideration the network users or followers. These network decision problems are formulated as non-linear bi-level programming problems. In this work, a continuous network design problem (CNDP) and discrete network design problem (DNDP) bi-level optimization programs are proposed and solved in the context of transportation planning. The solution strategy involved reformulation and linearization as a single-level program by introducing the optimality conditions of the lower level problem into the upper level problem. For the CNDP, an alternative linearization algorithm (modified …

Short-Term Test Results: Transitional Housing Energy Efficiency Retrofit In The Hot-Humid Climate, Florida Solar Energy Center, Karen Sutherland

FSEC Energy Research Center®

This project evaluates the renovation of a 5,800-ft², multiuse facility located in St. Petersburg, on the west coast of central Florida, in the hot-humid climate. An optimal package of retrofit measures was designed to deliver 30%-40% annual energy cost savings for this building with annual utility bills exceeding $16,000 and high base load consumption. Researchers projected energy cost savings for potential retrofit measures based on pre-retrofit findings and disaggregated, weather-normalized utility data. A cost-benefit analysis was conducted for the seven retrofit measures implemented; adding attic insulation and sealing soffits, tinting windows, improving whole-building airtightness, upgrading heating and cooling …

Numerical Evaluation Of The Stability Of Stationary Points Of Index-2 Differential-Algebraic Equations: Applications To Reactive Flash And Reactive Distillation Systems, D. A. Harney, T. K. Mills, N. L. Book

Chemical and Biochemical Engineering Faculty Research & Creative Works

The dynamic behavior of many chemical processes can be represented by an index-2 system of differential-algebraic equations. This index can be reduced by differentiation, but unfortunately the index reduced systems are not guaranteed to possess the same stability characteristics as that of the original system. When the set of differential-algebraic equations can be written in Hessenberg form, the matrix pencil of the linearized system can be used to directly evaluate the stability of a steady state without the need for index reduction. Direct evaluations of stability of reactive flash and reactive distillation are presented. It is also shown that a …

The Serial Resonant Antenna For The Large Field Of View Magnetic Resonance Imaging, Bo Zhu, Ed Xuekui Wu, Patrick Peng Gao, Peng Cao, Lijun Jiang

Electrical and Computer Engineering Faculty Research & Creative Works

A serial resonant antenna for the large field of view (FOV) magnetic resonance imaging (MRI) is presented. It consists of metallic patches cascaded through lumped capacitors in serial on the top layer of a grounded dielectric substrate. The theoretical analysis show that at the resonant frequency, uniformly distributed current with zero phase delay is produced independent of the antenna length, hence a uniform magnetic field for large FOV MRI can be achieved. Integrated with the L-shaped tunable matching network, the antenna can be tuned easily to operate rigorously at the working frequency of the MRI system. The numerical modeling, physical …

Improvement Of Heat Transfer Efficiency At Solid-Gas Interfaces By Self-Assembled Monolayers, Zhi Liang, William Evans, Tapan Desai, Pawel Keblinski

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Using Molecular Dynamics Simulations, We Demonstrate that the Efficiency of Heat Exchange between a Solid and a Gas Can Be Maximized by Functionalizing Solid Surface with Organic Self-Assembled Monolayers (SAMs). We Observe that for Bare Metal Surfaces, the Thermal Accommodation Coefficient (TAC) Strongly Depends on the Solid-Gas Interaction Strength. for Metal Surfaces Modified with Organic SAMs, the TAC is Close to its Theoretical Maximum and is Essentially Independent from the SAM-Gas Interaction Strength. the Analysis of the Simulation Results Indicates that Softer and Lighter SAMs, Compared to the Bare Metal Surfaces, Are Responsible for the Greatly Enhanced TAC. © 2013 …

Minimizing N-Points Interpolation Curvature, Heuristics For Solutions Using Arcs And Lines, Rahul Vishen, Marius C. Silaghi

Electrical Engineering and Computer Science Faculty Publications

Knowing a set of points on a curve, the interpolation problem is to hypothesize the location of the intermediary ones. A large set of interpolation techniques are known. We address the problem of generating a path with minimal maximum curvature, passing through N ordered points and joining the two end-points at predefined directions. This is related to R-geodesics, which have been used to generate paths with minimum average curvature between two given points that have to be joined at predefined directions and curvature. For example, when interpolating GPS points to reconstruct a vehicle’s trajectory, we may know that the centripetal …

Innovative Computing In Engineering And Medicine Ii, Khan Iftekharuddin, Dean Krusienski, Jiang Li

Undergraduate Research Symposium

Chairs: Drs. Khan Iftekharuddin, Dean Krusienski, & Jiang Li, Department of Electrical and Computer Engineering

Innovative Computing In Engineering And Medicine I, Chung-Hao Chen, Khan Iftekharuddin, Christian Zemlin

Undergraduate Research Symposium

Chairs: Drs. Chung-Hao Chen, Khan Iftekharuddin, & Christian Zemlin, Department of Electrical and Computer Engineering

The Santa Clara, 2013-02-07, Santa Clara University

The Santa Clara

No abstract provided.

Unidirectional Spaser In Symmetry-Broken Plasmonic Core-Shell Nanocavity, Xiangeng Meng, Urcan Guler, Alexander V. Kildishev, Koji Fujita, Katsuhisa Tanaka, Vladimir M. Shalaev

Birck and NCN Publications

The spaser, a quantum amplifier of surface plasmons by stimulated emission of radiation, is recognized as a coherent light source capable of confining optical fields at subwavelength scale. The control over the directionality of spasing has not been addressed so far, especially for a single-particle spasing nanocavity where optical feedback is solely provided by a plasmon resonance. In this work we numerically examine an asymmetric spaser - a resonant system comprising a dielectric core capped by a metal semishell. The proposed spaser emits unidirectionally along the axis of the semishell; this directionality depends neither on the incident polarization nor on …

Strong Heavy-To-Light Hole Intersubband Absorption In The Valence Band Of Carbon-Doped Gaas/Alas Superlattices, M. I. Hossain, Z. Ikonic, J. Watson, J. Shao, P. Harrison, Michael J. Manfra, O. Malis

Birck and NCN Publications

We report strong mid-infrared absorption of in-plane polarized light due to heavy-to-light hole intersubband transitions in the valence band of C-doped GaAs quantum wells with AlAs barriers. The transition energies are well reproduced by theoretical calculations including layer inter-diffusion. The inter-diffusion length was estimated to be 8 +/- 2 angstrom, a value that is consistent with electron microscopy measurements. These results highlight the importance of modeling the nanoscale structure of the semiconductors for accurately reproducing intra-band transition energies of heavy carriers such as the holes. (C) 2013 American Institute of Physics. [http://dx.doi.org/10.1063/1.4790305]

Single Network Adaptive Critics Networks-Development, Analysis, And Applications, Jie Ding, Ali Heydari, S. N. Balakrishnan

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Solving infinite time optimal control problems in an approximate dynamic programing framework with two-network structure has become popular in recent years. In this chapter, an alternative to the two-network structure is provided. We develop single network adaptive critics (SNAC) which eliminate the need to have a separate action network to output control. Two versions of SNAC are presented. The first version, called SNAC outputs the costates and the second version called J-SNAC outputs the cost function values. Special structure called Finite-SNAC to efficiently solve finite time problems is also presented. Illustrative infinite time and finite time problems are considered; numerical …

Online Optimal Control Of Nonaffine Nonlinear Discrete-Time Systems Without Using Value And Policy Iterations, Hassan Zargarzadeh, Qinmin Yang, S. Jagannathan

Electrical and Computer Engineering Faculty Research & Creative Works

Online optimal control of nonlinear discrete-time systems in a forward-in-time manner is a challenging problem due to a lack of closed-form solution to the Hamilton- Bellman-Jacobi (HJB) equation. Traditionally, value and policy iteration-based approximate optimal control schemes are developed in the literature by assuming that a significant number of iterations can be performed within a sampling interval which is not practical. By contrast, this book chapter introduces a novel online time-based optimal framework for nonlinear discrete-time systems by using both: (a) reinforcement learning and (b) online neural network approximation-based forward-in-time dynamic programming without using iterative methodology. The overall stability proof …

Optical Down-Conversion In Doped Znse:Tb3+ Nanocrystals, Sandip Das, K. C. Mandal

Faculty Publications

No abstract provided.

College Of Engineering News, Georgia Southern University

College of Engineering & Computing: News & Publications (2010-2023)

• Dr. Sungkyun Lim awarded grant from Georgia Power
• Dr. Junan Shen awarded GDOT research funds