Digital Commons Network^™

Photopolymerizable Nanocomposites For Holographic Recording And Sensor Application, Elsa Leite, Izabela Naydenova, Svetlana Mintova, Louis Leclercq, Vincent Toal

Articles

Novel nanocomposites consisting of a water soluble acrylamide–based photopolymer and colloidal zeolite nanoparticles of zeolite Beta and zeolite A were prepared. The interactions between the photopolymer components and zeolite nanoparticles in the photopolymerizable nanocomposites were characterized for the first time by 13C NMR and Visible spectroscopy. It was found that the zeolite Beta nanoparticles (up to 5% wt.) behave as a non-inert additive, resulting in an effective increase in layer thickness that causes doubling of the diffraction efficiency of the nanocomposite in comparison to that of the undoped photopolymer. On the other hand, the nanocomposite containing zeolite A nanoparticles showed …

Optical Properties Of Photopolymer Layers Doped With Aluminophosphate Nanocrystals, Elsa Leite, Tzvetanka Babeva, E Ng, Vincent Toal, Svetlana Mintova, Izabela Naydenova

Articles

The optical properties of photopolymer layers consisting of an acrylamide–based matrix and microporous aluminophosphate nanocrystals of AEI- type are investigated. The compatibility of the photopolymer doped with the nanoparticles is studied. The surface and volume properties of the layers with different levels of doping with microporous nanocrystals are characterized. The effective refractive indices and absorption coefficients of the doped photopolymer layers are determined and used to calculate the refractive index and porosity of pure AEI nanoparticles used as dopants. Volume transmission gratings were recorded in the doped photopolymer layers at different spatial frequencies. By spatial monitoring of the characteristic Raman …

Two-Way Diffusion Model For Short Exposure Holographic Grating Formation In Acrylamide-Based Photopolymer, Tzvetanka Babeva, Izabela Naydenova, Dana Mackey, Suzanne Martin, Vincent Toal

Articles

A theoretical model for formation of a short exposure holographic grating is presented. The model accounts for both monomer and polymer diffusion and distinguishes between short polymer chains capable of diffusing and long polymer chains that are immobile. It is shown that the experimentally observed decrease of diffraction efficiency at higher spatial frequency can be predicted by assuming diffusion of short-chain polymers away from the bright fringes. The time evolution of the refractive index modulation after short exposure is calculated and compared with experimental results. The effects of diffusion coefficients, polymerization rates, intensity and spatial frequency of recording on the …

Optimisation Of An Acrylamide-Based Photopolymer System For Holographic Inscription Of Surface Patterns With Sub-Micron Resolution, Kevin Trainer, Kevin Wearen, Dimana Nazarova, Izabela Naydenova, Vincent Toal

Articles

We describe the optimisation of the holographic patterning of sub-micrometer surface relief structures in an acrylamide-based photopolymer. A substantial improvement in the photoinduced surface relief resolution was achieved by altering the photopolymer chemical composition and by introducing a single step post recording thermal treatment of the layers. It was observed that, by optimisation of the chemical composition of the photopolymer layers, the maximum achievable spatial frequency increases from 200 l/mm to 550 l/mm. The improvement of the surface relief amplitude by alteration of the chemical composition is limited due to the fact that both decrease of the plasticiser and increase …

Study Of The Photoinduced Surface Relief Modulation In Photopolymers Caused By Illumination With A Gaussian Beam Of Light, Tzvetanka Babeva, Dana Mackey, Suzanne Martin, Izabela Naydenova, Vincent Toal

Articles

The formation of surface relief profile in photopolymerisable systems when illuminated with a focused beam of light is simulated numerically using a two-way diffusion model that takes account both for monomer and short polymer chains diffusion. The concentration and spatial distribution dynamics of monomer and short and long polymer chains are calculated. The surface profile is obtained from calculated components concentrations considering different densities of monomer and polymer. The influence of the illumination time, intensity and spot diameter on the surface profiles dynamics is discussed. A good agreement between the calculated and the experimentally measured profiles is observed thus demonstrating …

A Diffusion Model For Spatially Dependent Photopolymerization, Dana Mackey, Tzvetanka Babeva, Izabela Naydenova, Vincent Toal

Articles

Photopolymers represent an attractive class of optical recording materials due to properties such as high refractive index modulation, dry film processing, long shelf life, etc. Applications include holographically based devices for optical storage disks, optical interconnections, optical memories and filters. This paper will address the dynamics of short-exposure holographic grating formation; a new mathematical model is proposed with the aim of understanding the experimental observations of low diffraction efficiency in high spatial frequency gratings.

Vibration Phase Measurements Using Holographic Optical Elements, Viswanath Bavigadda, Raghavendra Jallapuram, Vincent Toal, Emilia Mihaylova

Articles

The application of an out-of-plane sensitive electronic speckle pattern interferometer (ESPI) using holographic optical element (HOE) to vibration amplitude and phase mapping is reported. The novelty of the proposed system is the use of a speckle reference wave stored in a reflection holographic optical element (HOE). The incorporation of a HOE minimizes the alignment difficulties. The HOE based ESPI system is compact containing only a diode laser, HOE and a digital CMOS camera. The measurement technique is a combination of time averaged ESPI and reference beam phase modulation in an unbalanced interferometer. The reference beam phase modulation is implemented by …

Altered Mitochondrial Function And Genome Frequency Post Exposure To Γ-Radiation And Bystander Factors, Fiona Lyng, Sharon Nugent,, Carmel E. Mothersill,, Colin Seymour, Brendan Mcclean,, James E. J. Murphy

Articles

PURPOSE:

To further evaluate irregular mitochondrial function and mitochondrial genome damage induced by direct γ-irradiation and bystander factors in human keratinocyte (HPV-G) epithelial cells and hamster ovarian fibroblast (CHO-K1) cells. This is as a follow-up to our recent reports of γ-irradiation-induced loss of mitochondrial function and mitochondrial DNA (mtDNA) damage.

Continued Viability: A Review Of The Life Sciences Library At Indiana University In A Time Of Institutional Change And Proposed Branch Library Downsizing, J B. Hill, Brian Winterman

Faculty Scholarship

There has been a growing realization that academic libraries need to change to serve a new generation of learners and researchers. Efforts to enhance the "Main Library" on campus with extended hours, coffee shops, and information commons have created modern, user-friendly environments that support changing student needs and expectations.  Generally fewer resources have been given to upgrading smaller branch libraries. The need to modernize older spaces along with the availability of electronic collections, campus demands for classroom/lab space and financial pressures on libraries have prompted a rethinking of the role of branch libraries. Actively pursuing initiatives to re-envision library spaces …

Supplementing Accelerated Reading With Class-Wide Interdependent Group-Oriented Contingencies, Danielle N. Pappas, Christopher H. Skinner, Amy L. Skinner

Faculty Publications - Graduate School of Counseling

An across-groups (classrooms), multiple-baseline design was used to investigate the effects of an interdependent group-oriented contingency on the Accelerated Reader (AR) performance of fourth-grade students. A total of 32 students in three classes participated. Before the study began, an independent group-oriented reward program was being applied (i.e., a student received access to a tangible reward after passing each AR comprehension test). This program was supplemented with an interdependent group-oriented contingency, and results showed that the number of quizzes passed per week increased immediately after the intervention was applied; however, this increase was not maintained. When students were divided into ability …

Possibilities: Kamil Jbeily–The Man And His Vision For The Texas Regional Collaboratives For Excellence In Science And Mathematics Teaching, Martha May Tevis, John Mcbride

Teaching and Learning Faculty Publications

No abstract provided.

An Adaptive Control Strategy For Dstatcom Applications In An Electric Ship Power System, Pinaki Mitra, Ganesh K. Venayagamoorthy

Electrical and Computer Engineering Faculty Research & Creative Works

Distribution static compensator (DSTATCOM) is a shunt compensation device that is generally used to solve power quality problems in distribution systems. In an all-electric ship power system, power quality issues arise due to high-energy demand loads such as pulse loads. This paper presents the application of a DSTATCOM to improve the power quality in a ship power system during and after pulse loads. The control strategy of the DSTATCOM plays an important role in maintaining the voltage at the point of common coupling. A novel adaptive control strategy for the DSTATCOM based on artificial immune system (AIS) is presented in …

Onboard Visual Tracking With Small Unmanned Aricraft Systesm (Uas), Ashraf Qadir

Theses and Dissertations

No abstract provided.

Complexity And Thresholding Phenomena In The Partitioning Problem, Scott D. Kerlin

Theses and Dissertations

No abstract provided.

Self-Objectification And Its Effects On Body Dissatisfaction And Cognitive Performance In Young And Older Women, Lauren Alexis Henrikson

Theses and Dissertations

No abstract provided.

Computer Simulation Study For The External Predrying Of Lignite Coal, Carlos Javier Bucaram

Theses and Dissertations

No abstract provided.

Ecosystem Services Assessment Of Grand Forks County, Hom J. Adhikari

Theses and Dissertations

No abstract provided.

Cdo Ratings And Systemic Instability Causes And Cure, John Crawford

Faculty Scholarship

No abstract provided.

2010-2011 Graduate Catalog, Armstrong Atlantic State University

Armstrong Office of the Registrar: Graduate Catalogs (Archived)

Academic catalog for Armstrong Atlantic State University.

Undergraduate And Graduate Catalog [2009-2010], Georgia Southern University

Undergraduate & Graduate Catalogs

No abstract provided.

2010-2011 Undergraduate Catalog, Armstrong Atlantic State University

Armstrong Office of the Registrar: Undergraduate Catalogs (Archived)

Academic catalog for Armstrong Atlantic State University.

Applying Transportation Forecasting To The Atlanta Area Public Transportation System, Aaron L. Taylor

College of Graduate Studies: Theses & Dissertations

In this thesis, we examine the implementation of volume delay functions to the Metropolitan Atlanta Rapid Transportation Authority (MARTA) system. Volume delay functions are n differentiable functions used to estimate the long-term distribution of user traffic on transportation systems. We will demonstrate the graphical behavior of these functions as well as explain the constraints for these functions. These tasks will be completed by developing a simplistic yet unrealistic model, demonstrate how the integral is used to estimate the total sum of this model, and then introduce the two functions which will be used in the analysis. The final task of …

Weighted Inverse Weibull And Beta-Inverse Weibull Distribution, Jing Xiong Kersey

College of Graduate Studies: Theses & Dissertations

The weighted inverse Weibull distribution and the beta-inverse Weibull distribution are considered. Theoretical properties of the inverse Weibull model, weighted inverse Weibull distribution including the hazard function, reverse hazard function, moments, moment generating function, coefficient of variation, coefficient of skewness, coefficient of kurtosis, Fisher information and Shanon entropy are studied. The estimation for the parameters of the length-biased inverse Weibull distribution via maximum likelihood estimation and method of moment estimation techniques are presented, as well as a test for the detection of length-biasedness in the inverse Weibull model. Furthermore, the beta-inverse Weibull distribution which is a weighted distribution is presented, …

Mahalanobis Taguchi System (Mts) As A Prognostics Tool For Rolling Element Bearing Failures, Ahmet Soylemezoglu, Sarangapani Jagannathan, Can Saygin

Electrical and Computer Engineering Faculty Research & Creative Works

In this paper, a novel Mahalanobis-Taguchi system (MTS)-Based fault detection, isolation, and prognostics scheme is presented. the proposed data-driven scheme utilizes the Mahalanobis distance (MD)-Based fault clustering and the progression of MD values over time. MD thresholds derived from the clustering analysis are used for fault detection and isolation. When a fault is detected, the prognostics scheme, which monitors the progression of the MD values, is initiated. Then, using a linear approximation, time to failure is estimated. the performance of the scheme has been validated via experiments performed on rolling element bearings inside the spindle headstock of a microcomputer numerical …

Dynamic System Eigenvalue Extraction Using A Linear Echo State Network For Small-Signal Stability Analysis - A Novel Application, Jiaqi Liang, Jing Dai, Ganesh K. Venayagamoorthy, Ronald G. Harley

Electrical and Computer Engineering Faculty Research & Creative Works

A large nonlinear dynamic system usually has complex dynamic modes corresponding to the system's eigenvalues. These eigenvalues govern the system's local behavior and thus are critical information for designing system operation and control strategies. Without the availability of the system's analytical model, which is often the case for large nonlinear systems, the system's eigenvalues need to be estimated. a linear echo state network (ESN) based method for extracting observable eigenvalues of a dynamic system together with the participation factors of these eigenvalues in the accessible system states is presented in this paper. a linear ESN is first trained to track …

Zero-Sum Two-Player Game Theoretic Formulation Of Affine Nonlinear Discrete-Time Systems Using Neural Networks, S. Mehraeen, T. Dierks, S. Jagannathan, M. L. Crow

Electrical and Computer Engineering Faculty Research & Creative Works

In this paper, the nearly optimal solution for discrete-time (DT) affine nonlinear control systems in the presence of partially unknown internal system dynamics and disturbances is considered. the approach is based on successive approximate solution of the Hamilton-Jacobi-Isaacs (HJI) equation, which appears in optimal control. Successive approximation approach for updating control input and disturbance for DT nonlinear affine systems are proposed. Moreover, sufficient conditions for the convergence of the approximate HJI solution to the saddle-point are derived, and an iterative approach to approximate the HJI equation using a neural network (NN) is presented. Then, the requirement of full knowledge of …

Southern Educator, Georgia Southern University

College of Education: News & Publications (2003-2023)

• Koballa Appointed as COE Dean
• Jack Miller Faculty Awards
• Fall 2010 Numbers
• Welcome New Faculty
• Another Georgia Teacher of the Year from Georgia Southern
• Counselor Educators of the Year – 2010
• Vafa Gasimova Muskie Fellow
• International Student Teacher Exchanges
• SMART Scholar Program
• Alumni Advisory Council Says "Yes!"
• Engraved Bricks: Next Order December 31
• One-Room Schoolhouse Moved to Botanical Garden
• Southern Educator Class Roll
• Staff News

Decentralized Nearly Optimal Control Of A Class Of Interconnected Nonlinear Discrete-Time Systems By Using Online Hamilton-Bellman-Jacobi Formulation, S. Mehraeen, Sarangapani Jagannathan

Electrical and Computer Engineering Faculty Research & Creative Works

In this paper, the direct neural dynamic programming technique is utilized to solve the Hamilton Jacobi-Bellman (HJB) equation online and forward-in-time for the decentralized nearly optimal control of nonlinear interconnected discrete-time systems in affine form with unknown internal subsystem and interconnection dynamics. Only the state vector of the local subsystem is considered measurable. the decentralized optimal controller design for each subsystem consists of an action neural network (NN) that is aimed to provide a nearly optimal control signal, and a critic NN which approximates the cost function. the NN weights are tuned online for both the NNs. It is shown …

Optimal Control Of Affine Nonlinear Continuous-Time Systems Using An Online Hamilton-Jacobi-Isaacs Formulation, T. Dierks, Sarangapani Jagannathan

Electrical and Computer Engineering Faculty Research & Creative Works

Solving the Hamilton-Jacobi-Isaacs (HJI) equation, commonly used in ℋ∞ optimal control, is often referred to as a two-player differential game where one player tries to minimize the cost function while the other tries to maximize it. in this paper, the HJI equation is formulated online and forward-in-time using a novel single online approximator (SOLA)-Based scheme to achieve optimal regulation and tracking control of affine nonlinear continuous-time systems. the SOLA-Based adaptive approach is designed to learn the infinite horizon HJI equation, the corresponding optimal control input, and the worst-case disturbance. a novel parameter tuning algorithm is derived which not only achieves …

Optimal Control Of Affine Nonlinear Continuous-Time Systems, T. Dierks, Sarangapani Jagannathan

Electrical and Computer Engineering Faculty Research & Creative Works

In this paper, the optimal regulation and tracking control of affine nonlinear continuous-time systems with known dynamics is undertaken using a novel single online approximator (SOL)-Based scheme. the SOLA-Based adaptive approach is designed to learn the infinite horizon continuous time Hamilton-Jacobi-Bellman (HJB) equation and its corresponding optimal control input. a novel parameter tuning algorithm is derived which not only ensures the optimal cost (HJB) function and control input are achieved, but also ensures the system states remain bounded during the online learning process. Lyapunov techniques show that all signals are uniformly ultimately bounded (UUB) and the approximated control signal approaches …