Digital Commons Network^™

Casimir Force For Complex Objects Using Domain Decomposition Techniques, Phillip R. Atkins, Weng Cho Chew, Mao Kun Li, Lin E. Sun, Zu Hui Ma, Li (Lijun) Jun Jiang

Electrical and Computer Engineering Faculty Research & Creative Works

A method for calculating the Casimir force between large, complex 3D objects is presented. Difficulties have previously arisen in broadband multiscale calculation using CEM methods. To expand the range of problems that can be calculated, we use an integral equation, domain decomposition method (DDM) and argument principle to derive the Casimir force formula. The broadband integral equation DDM, which is the augmented equivalence principle algorithm (A-EPA), allows for an efficient broadband solution of large, complex objects. A-EPA subdivides a complex problem into separate smaller subproblems that are later recombined into a reduced matrix. This yields a reduced number of unknowns …

Use Of Innovative Techniques To Enhance The Hydraulic Disinfection Efficiency Of Drinking Water Contact Tanks, J. J. Kattnig, S. K. Venayagamoorthy

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

The focus of this study was to understand the complex nature of flow dynamics within water disinfection contact tanks and to use this understanding in the development of beneficial tank modifications. Methods involved in this process included the use of computational fluid dynamics (CFD) and physical conservative tracer studies. Attempted tank alterations included the installation of baffles, inlet modification, and the use of industrial packing material. Tested modifications aimed at altering existing velocity fields to increase the hydraulic disinfection efficiency of a given system. Hydraulic efficiency was measured through the use of residence time distribution (RTD) curves and the well-known …

Overexpression Of Dcf1 Inhibits Glioma Through Destruction Of Mitochondria And Activation Of Apoptosis Pathway, Yuqiong Xie, Qang Li, Qingbo Yang

Electrical and Computer Engineering Faculty Research & Creative Works

Gliomas are the most common brain tumors affecting the central nervous system and are associated with a high mortality rate. DCF1 is a membrane protein that was previously found to play a role in neural stem cell differentiation. In the present study, we found that overexpression of dcf1 significantly inhibited cell proliferation, migration, and invasion and dramatically promoted apoptosis in the glioblastoma U251 cell line. DCF1 deletion mutations in the functional region showed that the complete structure of DCF1 was necessary for apoptosis. Furthermore, significantly lower tumorigenicity was observed in athymic nude mice by transplanting U251 cells overexpressing dcf1. To …

Association Between Vitamin D Receptor Gene Polymorphisms (Fok1 And Bsm1) And Osteoporosis: A Systematic Review, Zahra Mohammadi, Fateme Fayyazbakhsh, Mehdi Ebrahimi, Mahsa M. Amoli, Patricia Khashayar, Mahboubeh Dini, Reza Nezam Zadeh, Abbasali Keshtkar, Hamid Reza Barikani

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Osteoporosis is a Health Concern Characterized by Reduced Bone Mineral Density (BMD) and Increased Risk of Fragility Fractures. Many Studies Have Investigated the Association between Genetic Variants and Osteoporosis. Polymorphism and Allelic Variations in the Vitamin D Receptor Gene (VDR) Have Been Found to Be Associated with Bone Mineral Density. However, Many Studies Have Not Been Able to Find This Association. Literature Review Was Conducted in Several Databases, Including MEDLINE/Pubmed, Scopus, EMBASE, Ebsco, Science Citation Index Expanded, Ovid, Google Scholar, Iran Medex, Magiran and Scientific Information Database (SID) for Papers Published between 2000 and 2013 Describing the Association between Fok1 …

Shifting The Center: Piloting Embedded Tutoring Models To Support Multimodal Communication Across The Disciplines, Dustin Hannum, Joy Bracewell, Karen J. Head

English and Technical Communication Faculty Research & Creative Works

Beginning in its third year, the Georgia Tech Communication Center began investigating embedded tutoring as part of the overall slate of tutoring services already in practice. Because our center remains in a nascent period of identity, we continue to enjoy an unusual amount of flexibility in how we are exploring new ways to work within the tutoring milieu—that is, we have not had time to become complacent in providing services in particular ways. Additionally, because we are somewhat unusual given our professional staff of postdoctoral fellows, we have a broader ability to work across disciplines with instructors who are more …

Two-Center Interferences In Dielectronic Transitions In H₂⁺+ He Collisions, Shaofeng Zhang, Daniel Fischer, Michael Schulz, Alexander B. Voitkiv, Arne Senftleben, Alexander Dorn, Joachim Hermann Ullrich, Xinwen Ma, Robert Moshammer

Physics Faculty Research & Creative Works

Molecular two-center interferences in a collision induced excitation of H₂⁺ projectile ions, with simultaneous ionization of helium target atoms, are investigated in a kinematically complete experiment. In the process under investigation, the helium atom is singly ionized and simultaneously the molecular hydrogen ion is dissociated. Different collision mechanisms are identified and interference fringes emerging from a correlated first-order mechanism and from an independent second-order process are observed.

Ion-Li Collision Dynamics Studied With A Motremi, J. Goullon, R. Hubele, A. Laforge, Michael Schulz, X. Wang

Physics Faculty Research & Creative Works

In a novel experimental approach, a magneto-optical trap (MOT) is combined with a Reaction Microscope (ReMi) and implemented in an ion storage ring. Single ionization measurements were performed with 24 MeV O8+ and 6 MeV H+ projectiles and a state prepared lithium target. We obtained single-, double- and fully differential cross sections and observed features that we attribute to the structure and polarization of target initial states. © Published under license by IOP Publishing Ltd.

A Static Voltage Security Region For Centralized Wind Power Integration-Part I: Concept And Method, Tao Ding, Qinglai Guo, Rui Bo, Hongbin Sun, Boming Zhang

Electrical and Computer Engineering Faculty Research & Creative Works

When large wind farms are centrally integrated in a power grid, cascading tripping faults induced by voltage issues are becoming a great challenge. This paper therefore proposes a concept of static voltage security region to guarantee that the voltage will remain within operation limits under both base conditions and N-1 contingencies. For large wind farms, significant computational effort is required to calculate the exact boundary of the proposed security region. To reduce this computational burden and facilitate the overall analysis, the characteristics of the security region are first analyzed, and its boundary components are shown to be strictly convex. Approximate …

Nanocrystalline Rare Earth Phosphates From Glass Dissolution And Precipitation Reactions, Jaime George, Colin Ryan, Richard K. Brow

Materials Science and Engineering Faculty Research & Creative Works

A novel method is employed for the formation of rare earth phosphate solid solution compounds with unique mesoscopic structures. Europium- And lanthanum-doped sodium borate glass microspheres and particles, ranging in sizes from 50 to 300 μm, were reacted in 0.25 M K₂HPO₄ solution to form hollow spheres of nanocrystalline rare earth phosphate compounds by dissolution-precipitation reactions. The initially X-ray amorphous precipitated rare earth phosphate materials were heat-treated at 700°C for 2 h to form nanocrystalline compounds. Differential thermal analysis (DTA) experiments yield an average activation energy for crystallization of 394 ± 26 kJ/mol. X-ray diffraction (XRD) data …

An Evaluation Of Creep Behaviour In Friction Stir Welded Ma754 Alloy, Jiye Wang, Wei Yuan, Rajiv S. Mishra, Indrajit Charit

Materials Science and Engineering Faculty Research & Creative Works

Effect of friction stir welding (FSW) on microstructure and creep properties of oxide dispersion strengthened (ODS) alloy MA754 were investigated. Fine-grained microstructure developed in the weld zone. TEM results showed some degree of particle agglomeration as a result of intense material flow. Creep tests of the FSW material were carried out at 973 and 1073 K. Power law creep behavior was observed with stress exponent values of 6.9 and 6.3 at 973 and 1073 K, respectively. The results were compared to those of the as-received material. Creep resistance of FSW material was lower than that of as-received material associated with …

Spinel-Based Refractories For Improved Performance In Coal Gasification Environments, James G. Hemrick, Beth Armstrong, Angela Rodrigues-Schroer, Dominick Colavito, Jeffrey D. Smith

Materials Science and Engineering Faculty Research & Creative Works

Oak Ridge National Laboratory, in collaboration with Minteq International, Inc., Missouri University of Science and Technology and refractory end users, has developed novel refractory systems and techniques to reduce energy consumption of refractory lined vessels. The objective of this U.S. DOE funded project was to address the need for innovative refractory compositions by developing MgO-Al₂O₃ spinel gunnable refractory compositions utilizing new aggregate materials, bond systems, protective coatings, and phase formation techniques. Materials have been developed specifically for coal gasification environments and work has been performed to develop and apply low cost coatings using a colloidal approach for …

Oscillons And Oscillating Kinks In The Abelian-Higgs Model, Charilaos Tsagkarakis, V. Achilleos, F. K. Diakonos, D. J. Frantzeskakis, G. C. Katsimiga, X. N. Maintas, E. Manousakis, A. Tsapalis

Physics Faculty Research & Creative Works

We study the classical dynamics of the Abelian Higgs model employing an asymptotic multiscale expansion method, which uses the ratio of the Higgs to the gauge field amplitudes as a small parameter. We derive an effective nonlinear Schrödinger equation for the gauge field, and a linear equation for the scalar field containing the gauge field as a nonlinear source. This equation is used to predict the existence of oscillons and oscillating kinks for certain regimes of the ratio of the Higgs to the gauge field masses. Results of numerical simulations are found to be in very good agreement with the …

The Effect Of Using Different Rock Failure Criteria In Wellbore Stability Analysis, Reza Rahimi

Masters Theses

"Determination of the appropriate drilling fluid density by rock failure analysis is an essential step to control wellbore instability. To determine wellbore failure stresses, the rock strength has to be known, an appropriate constitutive model has to be selected, and finally an accurate rock failure criterion must be chosen. Linear-poro elastic modeling of the mechanical wellbore failure is the most common approach to investigate wellbore instability. Numerous failure criteria have been used for the rock failure analysis but there is not any commonly accepted agreement of which failure criteria to use. Rock failure criteria differ in two main characteristics. First, …

Development Of A Tribometer To Characterize Lubrication Layer Properties Of Self-Consolidating Concrete, Dimitri Feys, Kamal Khayat, Aurelien Perez-Schell, Rami Khatib

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

The Last Decade, Significant Advances Have Been Made in Investigating, Understanding and Predicting the Flow Characteristics during Pumping of Concrete. Kaplan Developed Theoretical Equations based on the Rheological and Tribological Properties of Concrete to Predict Pumping Pressures. Several Tribometers Were Developed to Characterize the Flow Properties of Concrete Along a Smooth Wall, But None of Them Allows the Use of Highly Workable Concretes. the Main Reason is that for the Calculation of the Yield Stress and Viscous Constant of the Lubrication Layer, the Concrete is Not Allowed to Be Sheared. in This Paper, a New Design for the Concrete Tribometer …

Statistical Analysis Of Sleep Patterns In Drosophila Melanogaster, Luyang Wang

Masters Theses

“Sleep is one of the most preserved and restorative behaviors of animals and is important in human health. Lack of sleep may cause numerous diseases. So the study of sleep rhythms is very essential and complicated. In order to simplify the process of studying sleep, the fruit fly Drosophila melanogaster, is utilized as a model organism for several reasons. Some of the molecular mechanisms that contribute to the circadian clock in the fruit fly were also found to generate similar cycles in mammals. In order to study sleep patterns in the fruit fly, experiments were designed and performed to …

Potential Acid Mine Drainage Treatment Utilizing Acidophilic Sulfate Reducing Bacteria In An Upflow Bioreactor, Elise Fay Kittrell

Masters Theses

"During coal and iron mining, pyrite is often exposed to oxygen, causing acid mine drainage (AMD). Acid mine drainage has characteristic traits of: a rust color, low pH levels (around 3 or 4) and high concentrations of sulfate, metal sulfates and heavy metals.

Sulfate reducing bacteria (SRB) are often utilized in acid mine drainage treatment by implementing them into biochemical reactors (BCR). As SRB break down various carbon sources, bicarbonate is produced, raising the pH and generating hydrogen sulfide which reacts with numerous metals. This approach can be troublesome, as SRBs do not thrive at low pH levels often associated …

Hard-Switched Switched Capacitor Converter Design, Lukas Konstantin Müller

Masters Theses

"Switched capacitor (SC) converters are becoming quite popular for use in DC-DC power conversion. The concept of equivalent resistance in SC converters is frequently used to determine the conduction losses due to the load current. A variety of methodologies have been presented in the literature to predict the equivalent resistance in hard-switched SC converters. However, a majority of the methods described are difficult to apply to general SC converter topologies. Additionally, previous works have not considered all nonidealities in their analysis, such as switching losses or stray inductances. This work presents a generalized and easy to use model to determine …

Techno-Economic And Life-Cycle Modeling And Analysis Of Various Energy Storage Technologies Coupled With A Solar Photovoltaic Array, Brian Andrew Peterson

Masters Theses

"Renewable energies, such as wind and solar, are a growing piece of global energy consumption. The chief motivation to develop renewable energy is two-fold: reducing carbon dioxide emissions and reducing dependence on diminishing fossil fuel supplies. Energy storage is critical to the growth of renewable energy because it allows for renewably-generated electricity to be consumed at times when renewable sources are unavailable, and it also enhances power quality (maintaining voltage and frequency) on an electric grid which becomes increasingly unstable as more renewable energy is added. There are numerous means of storing energy with different advantages, but none has emerged …

Corrosion Resistance Of Enamel Coating Modified By Calcium Silicate And Sand Particle For Steel Reinforcement In Concrete, Fujian Tang

Masters Theses

"Porcelain enamel has stable chemical property in harsh environments such as high temperature, acid and alkaline, and it can also chemically react with substrate reinforcing steel resulting in improved adherence strength. In this study, the corrosion resistances of enamel coating modified by calcium silicate and sand particles, which are designed for improved bond strength with surrounding concrete, were investigated in 3.5 wt% NaCl solution. It consists of two papers that describe the results of the study.

The first paper investigates the corrosion behavior of enamel coating modified by calcium silicate applied to reinforcing steel bar in 3.5 wt% NaCl solution …

Effect And Interactions Of Commercial Additives And Chloride Ion In Copper Electrowinning, Wenyuan Cui

Masters Theses

"This thesis is to understand and compare the effects and interactions of modified polysaccharide (HydroStar), polyacrylamide (Cyquest N-900) and chloride ion on copper electrowinning. A study of the nucleation and growth was conducted in a synthetic electrolyte (40 g/L Cu, 160 g/L H₂SO₄, 20 mg/L Cl-) with the addition of HydroStar or Cyquest N-900 using potential step measurements. The current responses generated were compared to theoretical models of nucleation and growth mechanisms. The nucleation and growth mechanism changed as function of potential and the presence of organic additives. The nucleation and growth mechanisms were confirmed using scanning electron microscopy (SEM). …

Polyurethane Foam Infill For Fiber Reinforced Polymer (Frp) Bridge Deck Panels: An Evaluation Of Core Alternatives Using Small Scale Experimental Testing, Matthew Scott Hopkins

Masters Theses

"Fiber reinforced polymer (FRP) decking is a concept that has been explored in recent decades as one solution to the performance issues of conventional concrete bridge decking. Many sandwich panel designs made of glass reinforced polyester or vinyl ester resin have been well developed, and manufactured using filament winding, hand lay-up, and extrusion methods. The major benefits of these panels was their light weight, corrosion resistance, fatigue performance, and potential for rapid field assembly. However, high initial costs coupled with small state budgets have kept them from main stream adoption. A viable alternative, is a foam/reinforced foam core sandwich panel …

An Iterative Algorithm For Variational Data Assimilation Problems, Xin Shen

Masters Theses

"Data assimilation is a very powerful and efficient tool to use collected raw data for improving model prediction in numerical weather forecasting, hydrology, and many other areas of geosciences. In this thesis, an iterative algorithm [23] of variational data assimilation with finite element method is utilized to study different models. One motivation for this fundamental mathematical study is to provide a potential tool for simulation of CO₂ sequestration by extending it to more realistic and sophisticated models in the future. The basic idea of variational data assimilation is to utilize the framework of optimal control problems. We apply the …

Hedge Fund Replication Using A Strategy Specific Modeling Approach, Sujit Subhash

Masters Theses

"Institutional investors and wealthy individuals have in the past allocated a significant portion of their portfolios to hedge funds with the expectation of unconditional and uncorrelated returns to the market. However, the financial crisis of 2008 has heightened investor sensitivity to the high fees, illiquidity, and lockup periods typically associated with hedge funds. Hedge fund indexes showing excellent returns and low volatility contain funds that are closed to new investments, while the performance of investable funds have been shown to be inferior to their non-investable counterparts. The lack of transparency and extreme variation in the performance of hedge funds make …

Performance Analysis Of Cutting Graphite-Epoxy Composite Using A 90,000 Psi Abrasive Waterjet, Aiswarya Choppali

Masters Theses

"Graphite-epoxy composites are being widely used in many aerospace and structural applications because of their properties: which include lighter weight, higher strength to weight ratio and a greater flexibility in design. However, the inherent anisotropy of these composites makes it difficult to machine them using conventional methods. To overcome the major issues that develop with conventional machining such as fiber pull out, delamination, heat generation and high tooling costs, an effort is herein made to study abrasive waterjet machining of composites. An abrasive waterjet is used to cut 1" thick graphite epoxy composites based on baseline data obtained from the …

Wavefunction Methods For The Accurate Characterization Of Water Clusters, J. Coleman Howard, Gregory S. Tschumper

Chemistry Faculty Research & Creative Works

Although the first ab initio Hartree-Fock computations of the water dimer were reported more than four decades ago, the detailed characterization of water clusters with sophisticated electronic structure techniques remains an important and vibrant area of research. The field of computational quantum chemistry has made significant advances since those pioneering studies. Geometry optimizations of the water dimer can now be carried out at the CCSDTQ level, and CCSD(T) energies can be computed with the aug-cc-pVTZ basis for clusters as large as (H₂O)₁₇. Some of these high-level studies are starting to reveal that the electronic structure is …

Part Viii: Health Care Analytics: Preface, Cilan H. Dagli

Engineering Management and Systems Engineering Faculty Research & Creative Works

No abstract provided.

A Study Of The Effect Of Basic Network Characteristics On System-Of-System Failure Propagation, Charles O. Adler, Cihan H. Dagli

Engineering Management and Systems Engineering Faculty Research & Creative Works

Real life examples of large system level failures in complex networked system are fairly common, with national and regional level power grids providing numerous cases where local failures have resulted in broad systemic failures. As large networked systems-of-systems are increasingly common, their susceptibility to large scale failures is of significant interest. This paper presents the results of a study using a simple model to investigate the impacts of basic architecture characteristics on the spread of failures through a system-of-system after an initial failure occurs. The study reported here uses a non-symmetric inter-grid only failure model to investigate the sensitivity of …

A Hybrid Neuro-Fuzzy Model To Forecast Inflation, David Lee Enke, Nijat Mehdiyev

Engineering Management and Systems Engineering Faculty Research & Creative Works

One of the key issues in constructing monetary policy is accurate prediction of the inflation level. The complex behavior and non-linear nature of the financial markets makes it hard to forecast the inflation rate precisely. This paper introduces a hybrid model that attempts to forecast the inflation rate with a combination of a subtractive clustering technique and a fuzzy inference neural network to overcome the shortcomings of the individual methodologies. Selected macroeconomic factors were used to predict the historical CPI data from the US Markets. The results of the proposed hybrid model are measured in RMSE.

Multi-Agent Based Architecture For Acknowledged System Of Systems, Siddhartha Agarwal, Lou E. Pape, Nil Kilicay-Ergin, Cihan H. Dagli

Engineering Management and Systems Engineering Faculty Research & Creative Works

Negotiation and collaboration issues in large organizations, with centralized control, across the globe, are becoming more complex with each passing day. The Acknowledged System of Systems (SoS) is a new approach that addresses some of these issues in a systematic, efficient manner. This paper proposes a hierarchical architectural framework to support Acknowledged SoS architecting and analysis for a Department of Defense (DoD) Acquisition process. A major challenge of the successful planning and evolution of an Acknowledged SoS is the lack of understanding of the impact of presence or absence of a system and its interface with another constituent system on …

Rapid Repair Of Severely Damaged Rc Columns Under Combined Loading Of Flexure, Shear, And Torsion With Externally Bonded Cfrp, Ruili He

Doctoral Dissertations

"This research aimed to develop a technique to rapidly repair reinforced concrete (RC) bridge columns for emergency service restoration after severe earthquake damage has occurred. Experimental and analytical studies were conducted to study the performance and effectiveness of the proposed repair method. The experimental study included a series of 1/2-scale RC square bridge columns originally tested to failure under constant axial and increasing cyclic lateral loadings resulting in combined flexure, shear, and torsion with different torsional-to-flexural moment ratios. Using externally bonded carbon fiber reinforced polymer (CFRP) sheets, each column was repaired over a 3-day period and then retested under the …