Engineering Commons^™

The Effect Of Native Oxide On Ion-Sputtering-Induced Nanostructure Formation On Gasb Surfaces, Osman El-Atwani, Jean Paul Allain, Anastassiya Suslova

Birck and NCN Publications

We have investigated the influence of native oxides on ion-sputtering-induced nanostructure formation on GaSb using in situ low energy ion scattering spectroscopy (LEISS) and X-ray photoelectron spectroscopy (XPS). Comparing an oxygen-free sample with a native oxide sample, LEISS and XPS reveal the effect of oxygen in generating higher surface Ga fractions during early stages (fluences of 1 x 10(15)-1 x 10(16) cm(-2)) of low energy (< 100 eV) Ar+ irradiation. Enhanced surface Ga and Ga2O3 fractions were also observed on "oxide free" samples exposed to air following irradiation. The results suggest preferential Ga oxidation and segregation on the top of the amorphous layer if oxygen is present on the surface. In addition, the native oxide also increases the fluence threshold for nanopatterning of GaSb surfaces by almost a factor of four during low energy irradiation. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4772980]

Study On The Start-Up Schemes For The Three-Stage Solid State Transformer Applications, Xiaohu Liu, Liming Liu, Hui Li, Keith Corzine, Tangtang Guo

Electrical and Computer Engineering Faculty Research & Creative Works

This paper investigates two stage-by-stage start-up schemes for a three-stage solid state transformer (SST) that includes a high frequency transformer. the DC-DC converter transformer current dynamics analysis presented in this paper shows that the stage-by-stage start-up scheme may lead to a relatively large transformer current. as a result, the DC-DC converter would suffer a relatively large input inrush current. the pre-charge start-up scheme can improve the transformer current profile during the transient. the detailed analysis of those two-start-up scheme is presented and the experimental verification on laboratory prototype proved the analysis of stage-by-stage start-up scheme. © 2012 IEEE.

A Depolymerization Based Model Of Neuron Growth Cone Shape And Motility, Neerajha Nagarajan

Master's Theses

Cell migration is a ubiquitous process underlying critical biological mechanisms like wound healing, cancer metastasis and even neuron growth cone motility. It is a critical process for the living organisms as it ensures proper functioning of the system, for example, crawling fibroblasts endure closure of wounds during wound healing. Here we focus our interest on neuron growth cones, a sensory and motile organelle present at the tip of extending neurites, like the axons, in neurons. These are responsible for neuron pathfinding onto specific targets and synapses, in responses to various guidance cues. Interestingly, the motility of the growth cones is …

Weather-Based Damage Prediction Models For Electric Distribution Networks, David W. Wanik

Master's Theses

From thunderstorms to hurricanes, electric distribution networks are subject to a wide range of warm weather storm events. Tropical Storm Irene (2011) and Hurricane Sandy (2012) are two events in recent memory that disrupted over half of The Connecticut Light and Power Company’s (CL&P) service territory, which left some customers without power for up to eleven days. This research study investigates a damage prediction framework for both thunderstorms and hurricanes that combines two generalized linear models to probabilistically determine the occurrence and extent of damages, known as trouble spots, to the overhead power distribution network. The models are inputted with …

A Finite Difference Implementation Of Phase Field Theory, Nicholas W. Oren

Master's Theses

Computationally handling cracks generally results in numerically unstable results. Specifically handling the infinite stresses at the crack tip as well as the abrupt change from virgin material to failed material creates numerical instabilities. This project seeks to determine if phase field physics theory, particularly the physics based modification developed by B. N. Cassenti, can be appropriately applied to cracks. Phase field theory introduces an additional state variable, the phase of the material. The phase represents the level of failure (by cracking), and diffuses the failure along a crack by specified equations. The modification, based on a variational principle, was tested …

Investigation Of In-Situ Immobilization Of Contaminated Sediments Using Alginate Gels For The Reduction Of Ecological Risk, Michael V. Podany Mr.

Master's Theses

Remediation methods for contaminated sediments include dredging, treatment and disposal and sediment isolation through capping. These methods are costly and adversely impact local ecosystems, in some cases causing major disturbances to the sediment bed and water column. A new remediation technique is proposed for slowly biodegradable contaminants using alginate hydrogels as a binding agent of sediment. The rational is that sediment particles bound in alginate hydrogel are less likely to be resuspended and the treatment is less disruptive than capping. Here we show addition of alginate increased the shear strength of sediment comprised of defined particle sizes. The increase in …

Analysis Of The Enzymatic Decomposition Of Barley Starch To Simple Carbohydrates, Mark Mathiew Williams

Master's Theses

The decomposition of barley starch plays a fundamental role in the final quality of fermented beverages in the brewing industry. The process of mashing involves steeping milled barley in water to stimulate the enzymatic decomposition of starch into simple carbohydrates. The temperature of the water significantly impacts the activity of the enzymes and in turn the resulting concentrations of sugar products. A kinetic model accurately predicting the types and quantities of sugars formed as a function of mash temperature would serve as a tool to tailor sugar profiles and optimize mashing procedures for a desired product.

Sixty minutes mashes were …

A Smartphone Design Approach To User Communication Interface For Administering Storage System Network, Weider Yu, Xiao Su, Jason Hansen

Faculty Publications

This paper investigates the feasibility and potential of using a mobile smartphone as a user administration control for storage system network. It includes the design and implementation of a mobile smartphone software system that can be used to perform system administration activities on the storage system without the need of using a laptop or desktop system. In the paper the design of some effective metaphors to present the storage system on the limited display area of a mobile smartphone device and the set of system features chosen for implementation are presented. Current storage system administration is limited to using storage …

Production Of A Banjo: Development Of Manufacturing Processes For Banjo Resonators,Rims, And Necks., Kevin N. Zollinger

Undergraduate Honors Theses

This body of research focused on the development of prototype tooling and manufacturing processes to produce resonators, rims, and necks for building banjos. The resulting fixtures and manufacturing processes were designed for ease of use by a single employee in a small shop environment. This research required proficiency in interdisciplinary mediums (ie. 2D modeling, 3D modeling, centerline tool path program generation, 2D modeling, 3D modeling, rendering, design, and woodworking).

The resonator required development of a matching set of forming surfaces, a bending/gluing fixture, a work-holding fixture for utilizing a wood lathe, and a steam chamber required for bending strips of …

Grain Size And Texture Effects On Deformation Behavior Of Az31 Magnesium Alloy, W. Yuan, R. S. Mishra

Materials Science and Engineering Faculty Research & Creative Works

Cold rolled AZ31 magnesium alloy sheet was subjected to friction stir processing to generate four average grain sizes ranging from 0.8 to 9.6 μm. the processed material exhibited a strong basal fiber texture with the c-axis tilted about 35-55° towards the processing direction. the grain size and texture dependence of mechanical behavior were evaluated by using tensile testing along two orthogonal directions. Remarkably high ductility of ~65% was achieved in relatively coarse-grained material that fractured without developing necking when tested in the processing direction. the ductility decreased significantly to ~10% for ultrafine grained material as the tensile yield strength increased …

Automatic Object Recognition And Registration Of Dynamic Heavy Equipment Using A Hybrid Ladar System, Mengmeng Gai

Department of Construction Engineering and Management: Dissertations, Theses, and Student Research

It has been a challenging subject to recognize dynamic objects from a scattered work environment because large and complex 3D site data obtained by a laser scanner makes it difficult to process itself in real or near real time. This thesis introduces a model-based automatic object recognition and registration framework, Projection-Recognition-Projection (PRP), to assist heavy equipment operators in rapidly perceiving 3D working environment at dynamic construction sites. In this study, a digital camera and a hybrid laser scanner were used to rapidly recognize and register dynamic target objects in a 3D space by separating target object’s point cloud data from …

Analysis And Characterization Of Residual Stresses In Pipe And Vessel Welds, Shaopin Song

LSU New Orleans Theses and Dissertations

This research sought to establish residual stress distribution characteristics in typical pipe and vessel welds by carrying out a comprehensive parametric study using an advanced sequentially coupled thermo-mechanical finite element procedure. The parametric study covered vessel and pipe components with a ranging radius to thickness ratio from r/t=2 to 100, for thickness ranging from t=1/4” to 10”. Component materials varied from low carbon steel to high alloy steels, such as stainless steel and titanium alloy. Furthermore, a structural mechanics based framework is proposed to generalize through-thickness residual stress distributions for a broad spectrum of joint geometry and welding conditions. The …

Odor Monitoring At Wastewater Treatment Plants, Natasha Halageri

LSU New Orleans Theses and Dissertations

Hydrogen sulfide (H₂S) is notable for its toxicity and corrosion is one of the major sources of odor in wastewater treatment plants. Evaluation of existing or potential odor problems requires knowledge of the type of compounds likely to cause such problems and the mechanism of their formation in wastewater systems which is discussed in this paper. For the present study, the East Bank wastewater treatment plant was chosen since it is the largest wastewater treatment facility within Jefferson Parish, Louisiana. To combat the odor problems in this facility, a monitoring program was designed and developed to characterize the …

An Investigation Of The Optical Properties Of Disordered Silicon Nanowire Mats, Hua Bao, Weixia Zhang, Liangliang Chen, Haoxiang Huang, Chen Yang, Xiulin Ruan

Birck and NCN Publications

Optical reflectance spectra of three disordered silicon nanowire mats with average diameters of 40, 60, and 80 nm are investigated both experimentally and theoretically. The total hemispherical reflectance spectra from 200 to 1600 nm wavelength are first measured. All three samples exhibit reflectance about 15% to 20% within the ultraviolet band. As the wavelength becomes longer, the reflectance will first increase to around 50% and then decrease to below 20%. Such reflectance spectra are attributed to the combined effect of silicon dielectric function, the nanowire geometry, and the volume fraction of the mats. An analytical method based on Mie scattering …

Structural Design Of Flexible Etfe Atrium Enclosures Using A Cable-Spring Support System, Ryan Paul Bessey

Theses and Dissertations

This research designed and analyzed an innovative structural support system for ETFE (ethylene tetrafluoroethylene) atrium roofs between buildings. A cable-spring system was conceived, which is much lighter and more flexible than arches, frames, trusses, and beams which usually support ETFE roofs. Flexibility was a desirable property because the displacements may vary significantly among the buildings supporting the ETFE atrium roof during wind and seismic loading. The springs in the cable-spring system allow large differential displacements without exerting large support reactions on the buildings. The flexibility of the cable-spring system was compared to the cable-strut system which is used to support …

Spatiotemporal Capacity Management For The Last Level Caches Of Chip Multiprocessors, Dongyuan Zhan

School of Computing: Dissertations, Theses, and Student Research

Judicious management of on-chip last-level caches (LLC) is critical to alleviating the memory wall of chip multiprocessors (CMP). Although there already exist many LLC management proposals, belonging to either the spatial or temporal dimension, they fail to capture and utilize the inherent interplays between the two dimensions in capacity management. Therefore, this dissertation is targeted at exploring and exploiting the spatiotemporal interactions in LLC capacity management to improve CMPs' performance. Based on this general idea, we address four specific research problems in the dissertation.

For the private LLC organization, prior-art proposals can improve the efficacy of inter-core cooperative caching at …

High Performance Low Temperature Solid Oxide Fuel Cells With Novel Electrode Architecture, Yu Chen, Qian Liu, Zhibin Yang, Fanglin Chen, Minfang Han

Faculty Publications

In this study, we have fabricated high performance low temperature solid oxide fuel cells (LT-SOFCs) with both acicular anodes and cathodes with thin Gd-doped ceria (GDC) electrolyte film. The acicular Ni-Gd_0.1Ce_0.9O_2−δ (Ni-GDC) anode was prepared using freeze drying tape casting, while the hierarchically porous cathode with nano-size Sm_0.5Sr_0.5CoO₃ (SSC) particles covering an acicular GDC skeleton was prepared by a combination of freeze drying tape casting and self-rising approaches. The acicular electrodes with 5–200 μm pores/channels enhance mass transport, while SSC particles of about 50 nm in the cathode promote …

Environmental Justice Ties To Electronic Travel Surveys And Transit Accessibility, Nicholas A. Hart

Master's Theses

No abstract provided.

Plantar Measurements To Determine Success Of Surgical Correction Of Stage Iib Adult Acquired Flatfoot Deformity, Erika Matheis

Theses and Dissertations

Adult Acquired Flatfoot Deformity (AAFD) is a progressive disease characterized by mechanical degeneration of the soft tissue structure in the arch of the foot that leads to changes in joint alignment. Surgical intervention commonly via tendon transfer and bony osteotomy is used to restore arch architecture, however there is a lack of quantitative assessments that measure the success of the surgical correction in vivo. Using plantar pressures via Tekscan® HR Mat and surveys (SF-36, FAOS), pre-operative and post-operative measures for six participants were defined, analyzed and compared. A paired t-test showed significant lateral shift for percent body weight during walking …

The Effects Of Observations And Maneuvers On Orbit Solutions, Christine M. Schudrowitz

Theses and Dissertations

The purpose of this research is to characterize the performance of the optimal sequential filter used in ODTK with a maneuvering satellite. Specifically, this thesis sought to characterize the performance using two scenarios: performance with a maneuver in between passes and performance with a limited number of measurements. The performance of the filter is evaluated by analyzing the covariance values generated during the orbit estimation process. Larger covariance values signify reduced performance of the filter. Several variables for the maneuvering satellite are used, including the maneuver direction and the maneuver magnitude. The time of the maneuver is also varied, which …

A Building Energy Efficiency Optimization Method By Evaluating The Effective Thermal Zones Occupancy, Anna Laura Pisello, Michael Bobker, Franco Cotana

Publications and Research

Building energy efficiency is strongly linked to the operations and control systems, together with the integrated performance of passive and active systems. In new high quality buildings in particular, where these two latter aspects have been already implemented at the design stage, users’ perspective, obtained through post-occupancy assessment, has to be considered to reduce whole energy requirement during service life. This research presents an innovative and low-cost methodology to reduce buildings’ energy requirements through post-occupancy assessment and optimization of energy operations using effective users’ attitudes and requirements as feedback. As a meaningful example, the proposed method is applied to a …

Complexity Of Bed-Load Transport In Gravel Bed Streams: Data Collection, Prediction, And Analysis, Darren D. Hinton

Theses and Dissertations

Bedload transport has long been known for its complexity. Despite decades of research, significant gaps of understanding exist in the ability to assess and predict bedload movement. This work introduces a comprehensive bedload database that is a compilation of field samples collected over the past 40 years; compares prediction formulae using a subset of the database; evaluates the influence of the armor layer on stream response to sediment input based on a hypothesis linked to one of the tested formulae, presents a mathematically manipulation of the empirical Pagosa Good/Fair formula for bedload transport into a format similar to the semi-empirical …

Effects Of Crossflow Velocity And Transmembrane Pressure On Microfiltration Of Oil-In-Water Emulsions, Nikolai V. Priezjev, Tohid Darvishzadeh

Mechanical and Materials Engineering Faculty Publications

This study addresses the issue of oil removal from water using hydrophilic porous membranes. The effective separation of oil-in-water dispersions involves high flux of water through the membrane and, at the same time, high rejection rate of the oil phase. The effects of transmembrane pressure and crossflow velocity on rejection of oil droplets and thin oil films by pores of different cross-section are investigated numerically by solving the Navier-Stokes equation. We found that in the absence of crossflow, the critical transmembrane pressure, which is required for the oil droplet entry into a circular pore of a given surface hydrophilicity, agrees …

Fast Admittance Computation For Tsv Arrays, Dazhao Liu, Siming Pan, Brice Achkir, Jun Fan

Electrical and Computer Engineering Faculty Research & Creative Works

A fast method to calculate the admittance matrix of through Silicon Vias (TSVs) is proposed in this paper. the silicon dioxide layers are equivalently modelled using the bound charge on the conductor surfaces as well as on the dielectric interface between the silicon dioxide and the silicon regions. Unknown surface densities of both the free and bound charge are expanded using the axial harmonics. Galerkin's method is then applied to obtain the capacitance and conductance matrices. the proposed method is validated with a full wave 2D cross-sectional analysis tool for a typical TSV pair structure. Comparisons with popular closed-form expressions …

Alternative Aefie-Efie Method For Broadband Cem Modeling, Jia Liu, Li (Lijun) Jun Jiang

Electrical and Computer Engineering Faculty Research & Creative Works

It is well known that the electric field integral equation (EFIE) has the low frequency breakdown problem while the Augmented electric field integral equation (AEFIE) method has the high frequency breakdown issue. To obtain a unified method that works for both low and high frequencies without manual switching of methods, a novel and simple method is proposed in this paper. It uses AEFIE and EFIE to compensate each other iteratively in all frequency regimes to guarantee the accuracy of the solution. As a result, it effectively extends AEFIE to the high frequency regime and extends EFIE to the low frequency …

Electromagnetic Properties Of Metal Granular Composite Materials For Emc Applications, Takanori Tsutaoka, Aiko Tsurunaga, Teruhiro Kasagi, Kenichi Hatakeyama, Marina Koledintseva

Electrical and Computer Engineering Faculty Research & Creative Works

Electromagnetic properties of copper and Fe₅₅Ni₄₅alloy (Permalloy) composite materials have been studied by measuring the relative complex permeability (µ_r = µ_r’– jµ_r”), and permittivity (Σ_r = Σ_r’– jΣ_r”) spectra over the microwave range, as well as the a.c. electrical conductivity σac spectra. The variation of σ_ac and Σ_r with particle content shows the insulator-metal transition due to the percolation effect. The effective cluster model can be applied to the percolation effect in permittivity. The permeability spectra in Permalloy composites, which contain the percolated particles, …

Analytical Representations For Frequency Dependences Of Microwave Permeability, Konstantin N. Rozanov, Marina Koledintseva

Electrical and Computer Engineering Faculty Research & Creative Works

Electromagnetic materials applied to solve various EMC and EMI problems require adequate analytical description of their RF and microwave material parameters. This is necessary for numerical optimization of wideband electromagnetic performance of devices incorporating these materials. The paper discusses the shape of frequency dependences of microwave permeability in homogeneous materials and composites. The Lorentzian frequency dispersion law is shown to allow for rather accurate description of all types of magnetic loss peaks, including those related to the ferromagnetic resonance and the effect of eddy currents. To model wideband electromagnetic performance of composites, mixing laws are typically used. The problem is …

Information Theoretic Approaches Towards Regulatory Network Inference, Vijender Chaitankar

Theses and Dissertations

In spite of many efforts in the past, inference or reverse engineering of regulatory networks from microarray data remains an unsolved problem in the area of systems biology. Such regulatory networks play a critical role in cellular function and organization and are of interest in the study of a variety of disease areas and ecotoxicology to name a few. This dissertation proposes information theoretic methods/algorithms for inferring regulatory networks from microarray data. Most of the algorithms proposed in this dissertation can be implemented both on time series and multifactorial microarray data sets. The work proposed here infers regulatory networks considering …

Capacitance Calculation Of Tsvs Using An Integral Equation Method Based On Partial Capacitances, Hanfeng Wang, Yaojiang Zhang, Albert E. Ruehli, Jun Fan

Electrical and Computer Engineering Faculty Research & Creative Works

An integral equation method based on partial capacitances is used to extract the capacitance between two through-silicon-vias (TSVs). the unrealistic assumption of equal potential along the vertical interface of silicon dioxide (SiO2) coating of TSVs in the analytical method has been removed by introducing unknown equivalent charges. the Galerkin method is used here to solve the unknown charge densities in the integral equation and thus, the capacitance between two TSVs can be efficiently calculated. the results are validated by comparing the extracted capacitances with commercial software based on the finite element method. the accuracy and efficiency have been demonstrated. © …

Using Fsv In High-Speed Channel Characterization And Correlation, Jiangfan Zhang, Jianmin Zhang, Jane Lim, Kelvin Qiu, Rick Brooks, Bill Chen

Electrical and Computer Engineering Faculty Research & Creative Works

In modern high performance networking systems, high-speed channels are among the most concerns due to the channel loss, discontinuities and crosstalk as data rate reaches 15 Gbps (Gigabit per second) and above through backplane. Full-wave modeling and system level simulations are widely used to estimate the performance for high-speed channels. Due to the variations and uncertainties associated with the simulation and manufacturing, correlation between simulation and measurement is often used to gain confidence on the channel performance prediction. in this paper, a high-speed channel including the portion inside a high-end ASIC (Application-Specific Integrated Circuit) package and the portion on a …