Physical Sciences and Mathematics Commons^™

Device Architectures In Organic Photovoltaics, James T. Mcleskey Jr

Turkish Journal of Physics

The various device structures used in organic polymer solar cells are reviewed. The operating principles behind these devices are explained in order to provide the reasoning behind the different structures. The incorporation of nanostructures into both bilayer and bulk heterojunction devices to improve exciton separation, charge transport, and light absorption is discussed. Novel ideas such as electrospun fibers and supramolecules are also covered. Finally, the impact of these structures on overall efficiency is evaluated.

Amorphous And Micromorph Si Solar Cells: Current Status And Outlook, Vitaliy Avrutin, Natalia Izyumskaya, Hadis Morkoç

Turkish Journal of Physics

An overview of the current status and prospects of thin-film Si photovoltaics, including both hydrogenated amorphous and microcrystalline Si as well their combination known as micromorph solar cells, with a major focus on the technological development is given. Although thin-film Si solar cells have been one of the first commercially successful photovoltaic devices, today they face a tremendous challenge from variety of bulk Si technologies (mono- and multicrystalline Si) and compound-semiconductor thin-film solar cells, both of which have managed to substantially reduce the production cost and improve power conversion efficiency. Thin-film Si photovoltaics benefiting from the mighty mainstream Si industry …

Electron Field Emission From Nanostructured Semiconductors Under Photo Illumination, Oktay Yilmazoglu, Anatoli Evtukh, Shihab Al-Daffaie, Jens-Peter Biethan, Dimitris Pavlidis, Vladimir Litovchenko, Hans L. Hartnagel

Turkish Journal of Physics

New device concepts and materials for the fabrication of compact high-frequency vacuum sources and micro-nano-integrated X-ray sources are of particular interest for broadband communication, security screening of packages and chemical materials, biomedical examination, and other applications. This article integrates results on GaN- and ZnO-based nano and self-assembled structures. They were used as field emitter tips for cold electron emission at high local electric fields as well as for photoassisted field emitters to generate bunched electrons directly from the emitter tip. The results on functional field emitters as cold electron sources will be presented. They are key elements for building, among …

Nanosphere Lithography - Exploiting Self-Assembly On The Nanoscale For Sophisticated Nanostructure Fabrication, Eser Metin Akinoglu, Anthony John Morfa, Michael Giersig

Turkish Journal of Physics

We demonstrate the fabrication of sophisticated nanostructures using nanosphere lithography (NSL). These include periodic triangular and pyramidal islands as well as periodically perforated thin films and cavities on the nano- and microscale. Furthermore, periodic arrays of vertically standing multiwalled carbon nanotubes are grown by plasma enhanced chemical vapor deposition from catalyst islands that were prepatterned by NSL. Moreover, we discuss the applicability of NSL to rough surfaces and show that the ratio between nanosphere size and roughness is determinant of the resulting nanostructure produced. Excellent, limited, and bad applicability of NSL are shown for smooth, rough, and very rough surfaces, …

The Evaluation Of An Environmental Leadership And Service Program's Effectiveness, Roberta Harlow Mcfarland

Walden Dissertations and Doctoral Studies

According to a recent report from the National Center for Educational Statistics, approximately 20% of the United States' high-school aged population is at risk of dropping out of high school, an outcome that strongly limits participation in economic and educational opportunities. The importance of earning a high school diploma has increased many local districts' efforts to close graduation gaps across the student population. Accordingly, this study evaluated a recuperative environmental leadership and service (EL&S) program in a northwestern local district to ascertain its effectiveness in providing at-risk students the personal and academic support required for high school graduation. Following the …

Food Safety Knowledge And Self-Reported Practices Of Food Handlers In Jamaica, Marcia Annmarie Thelwell-Reid

Walden Dissertations and Doctoral Studies

Food-borne illnesses are responsible for disease globally. One of the most important strategies for combating food-borne diseases is the training of food handlers. Using social cognition theory as a framework, the purpose of this study was to assess the effectiveness of the mandatory training program for food handlers in a rural parish in Jamaica. A cross-sectional survey, using self-administered questionnaires, was used to assess and compare food safety knowledge and self-reported practices of food handlers trained in 2 government training programs, while using untrained food handlers as controls. Descriptive and inferential statistics such as t test, chi-square test, and ANOVA …

Diffusion Of Social Network Technology And Overuse Among Health Industry Knowledge Workers, Abdel Rahman Toure

Walden Dissertations and Doctoral Studies

Many organizations now realize the important role of social network technology (SNT) in building social capital and hence broadening their customer base. However, observations have indicated that, while working, many knowledge workers use SNT to engage in non-job related activities, potentially leading to a decrease in productivity. The purpose of this study was to examine the relationship between the usage of SNT and productivity in the health sector. The theoretical foundation of this study emanated from Rogers's theory of diffusion of innovations and Campbell, Rodney, Scott, and Christopher's theory of performance. Collection of data involved a self-administered survey designed with …

Business Drivers For Environmental Regulations Compliance In Ghana's Mining Sector, Georgina Angorkor Ahorbo

Walden Dissertations and Doctoral Studies

Ghana's mining sector is a significant contributor to the national economy; however, environmental degradation continues to stigmatize the sector. The purpose of this phenomenological study was to explore experiences and perspectives of middle managers on how to drive compliance with EPA regulations and standards in Ghana's mining sector. Ajzen's theory of planned behavior was the conceptual framework for this phenomenological study. A purposive sample of 20 middle managers from Ghana's mining sector participated in interviews, which were transcribed and then coded to generate common themes. The primary research question involved exploring factors that promote employee compliance in Ghana's mining sector. …

Supporting And Securing Personal Mobile Devices Within An Existing Information Technology Environment, George Allen Patton

Walden Dissertations and Doctoral Studies

Personal mobile devices are becoming integrated into the daily operations of business. Managers are realizing that employees who are allowed to use personal mobile devices to access corporate information systems may reduce costs as users buy their own devices. The problem was that managers have a limited understanding of the need to secure or support personal mobile devices. The purpose of this survey study was to examine the relationship between employees' desire to use personal mobile devices and corporation needs for security and support. Hypotheses were tested by examining the relationships between the requirement to support and secure personal mobile …

Refining Computerized Physician Order Entry Initiatives In An Adult Intensive Care Unit, Chevita Fuller

Walden Dissertations and Doctoral Studies

Computerized physician order entry (CPOE) is used in healthcare organizations to improve workflow processes and transcription, as well as to prevent prescribing errors. Previous research has indicated challenges associated with CPOE for end-users that predispose patients to unsafe practices. Unsafe CPOE practices can be detrimental within the intensive care unit (ICU) setting due to the complexity of nursing care. Consequently, end-user satisfaction and understanding of CPOE and electronic health record (EHR) functionality are vital to avoid error omissions. CPOE initiatives should be refined post system implementation to improve clinical workflow, medication processes, and end-user satisfaction. The purpose of this quality …

Strengthening The Legal And Institutional Effectiveness For Transboundary Biodiversity Conservation In The ‘Heart Of Borneo’, Michelle Mei Ling Lim

Research Collection Yong Pung How School Of Law

The Heart of Borneo ('HoB') transboundary initiative spans the territory of Malaysia, Indonesia and Brunei. In this article I evaluate the HoB against governance criteria for effective transboundary conservation. This approach provides the framework for proposing what complementary reforms may be needed to improve the effectiveness of the initiative. Governance issues and the lack of political buy-in are identified as the most significant impediments to successful transboundary biodiversity conservation in the HoB. A further limitation stems from the failure to develop meaningful legal instruments and supporting institutions. This article recommends improvements to legal instruments and the evaluation and design of …

Wireless Ad Hoc Networks Connectivity Assessment And Relay Node Deployment, Maggie Xiaoyan Cheng, Yi Ling, Brian M. Sadler

Computer Science Faculty Research & Creative Works

We consider the network connectivity problem in a wireless ad hoc network. Network connectivity is measured by the conductance of the network, also called the Cheeger constant of the graph. A partition algorithm based on this measure is developed that divides the network at the bottleneck area. After the network is bisected, a relay node may be deployed between the two parts to increase the conductance of the network. The relay node deployment problem is formulated as an integer linear program to maximize the number of connections between the nodes on the two sides of the cut, and then a …

A Regression Model To Investigate The Performance Of Black-Scholes Using Macroeconomic Predictors, Timothy A. Smith, Ersoy Subasi, Aliraza M. Rattansi

Publications

As it is well known an option is defined as the right to buy sell a certain asset, thus, one can look at the purchase of an option as a bet on the financial instrument under consideration. Now while the evaluation of options is a completely different mathematical topic than the prediction of future stock prices, there is some relationship between the two. It is worthy to note that henceforth we will only consider options that have a given fixed expiration time T, i.e., we restrict the discussion to the so called European options. Now, for a simple illustration of …

Computational Models For Nanosecond Laser Ablation, Harihar Khanal, David Autrique, Vasilios Alexiades

Publications

Laser ablation in an ambient environment is becoming increasingly important in science and technology. It is used in applications ranging from chemical analysis via mass spectroscopy, to pulsed laser deposition and nanoparticle manufacturing. We describe numerical schemes for a multiphase hydrodynamic model of nanosecond laser ablation expressing energy, momentum, and mass conservation in the target material, as well as in the expanding plasma plume, along with collisional and radiative processes for laser-induced breakdown (plasma formation). Numerical simulations for copper in a helium background gas are presented and the efficiency of various ODE integrators is compared.

Mapreduce Based Parallel Suffix Tree Construction For Human Genome, Umesh Chandra Satish, Praveenkumar Kondikoppa, Seung Jong Park, Manish Patil, Rahul Shah

Computer Science Faculty Research & Creative Works

Genome indexing is the basis for many bioinformatics applications. Read mapping (sequence alignment) is one such application where the goal is to align millions of short reads against reference genome. Several tools are available for read mapping which rely on different indexing techniques to expedite the alignment process. However, many of these contemporary alignment programs are sequential, memory intensive and cannot be easily scaled for larger genomes. Suffix tree is one of the most widely used data structures for indexing strings (genomes). Building a scalable suffix-tree based tool is particularly challenging due to the difficulties involved in parallel construction of …

Impact Of Loss Synchronization On Reliable High Speed Networks: A Model Based Simulation, Suman Kumar, Lin Xue, Seung Jong Park

Computer Science Faculty Research & Creative Works

Contemporary nature of network evolution demands for simulation models which are flexible, scalable, and easily implementable. In this paper, we propose a fluid-based model for performance analysis of reliable high-speed networks. In particular, this paper aims to study the dynamic relationship between congestion control algorithms and queue management schemes, in order to develop a better understanding of the causal linkages between the two. We propose a loss synchronization module which is user configurable. We validate our model through simulations under controlled settings. Also, we present a performance analysis to provide insights into two important issues concerning 10 Gbps high speed …

Coupling Graphs, Efficient Algorithms And B-Cell Epitope Prediction, Liang Zhao, Steven C. H. Hoi, Zhenhua Li, Limsoon Wong, Hung Nguyen

Research Collection School Of Computing and Information Systems

Coupling graphs are newly introduced in this paper to meet many application needs particularly in the field of bioinformatics. A coupling graph is a two-layer graph complex, in which each node from one layer of the graph complex has at least one connection with the nodes in the other layer, and vice versa. The coupling graph model is sufficiently powerful to capture strong and inherent associations between subgraph pairs in complicated applications. The focus of this paper is on mining algorithms of frequent coupling subgraphs and bioinformatics application. Although existing frequent subgraph mining algorithms are competent to identify frequent subgraphs …

Aerogels As Diverse Nanomaterials, Abhishek N. Bang

Doctoral Dissertations

"Aerogels are 3-D light-weight nanoporous materials pursued for their low thermal conductivity, low dielectric constant and high acoustic attenuation. Those exceptional macroscopic properties of aerogels are dependent on the chemical nature of nanoparticles, complex hierarchical solid skeletal framework and porosity. Also, the free space can become host for functional guests such as pharmaceuticals. In chapter I, we investigated randomly mesoporous bio-compatible polymer-crosslinked dysprosia aerogels as drug delivery vehicles and demonstrated storage and release of drugs under physiological conditions. Comparative study with ordered and randomly mesoporous silica showed high drug uptake and slower release rate for random nanostructures (silica or dysprosia) …

Speciation Dynamics Of An Agent-Based Evolution Model In Phenotype Space, Adam David Scott

Doctoral Dissertations

"This dissertation is an exploration of phase transition behavior and clustering of populations of organisms in an agent-based model of evolutionary dynamics. The agents in the model are organisms, described as branching-coalescing random walkers, which are characterized by their coordinates in a two-dimensional phenotype space. Neutral evolutionary conditions are assumed, such that no organism has a fitness advantage regardless of its phenotype location. Lineages of organisms evolve by limiting the maximum possible offspring distance from their parent(s) (mutability, which is the only heritable trait) along each coordinate in phenotype space. As mutability is varied, a non-equilibrium phase transition is shown …

The Role Of Potential Antioxidant In Medicinal Drug-Induced Oxidative Stress, Weili Fan

Doctoral Dissertations

"Most medicinal drugs have adverse effects. Among the most commonly used of these drugs are several types, known as "oxidative drugs". These are believed to cause adverse effects that induce oxidative stress, an imbalance of generation and detoxification of reactive oxygen species. So it is a reasonable assumption that the antioxidant might alleviate the toxicity induced by these drugs. N-acetylcysteine (NAC), a synthetic thiol, is a free-radical scavenger and a precursor of glutathione (the main endogenous antioxidant). However, the negative charge of NAC at physiological pH limits its bioavailability. N-acetylcysteineamide (NACA) is neutral in charge and is believed to have …

Part I: In-Situ Fluorometric Quantification Of Microalgal Neutral Lipids Part Ii: Thermal Degradation Behavior Of Investment Casting Polymer Patterns, Hongfang Zhao

Doctoral Dissertations

"Research described in this dissertation covers two topics. Part-I is focused on in-situ determination of neutral lipid content of microalgae using a lipophilic fluorescent dye. The traditional Nile red stain-based method for detecting microalgal intracellular lipids is limited due to varying composition and thickness of rigid cell walls. In this study, the addition of dilute acid and heating of solution, were found to greatly enhance staining efficiency of Nile red for microalgal species evaluated. Oil-in-water (O/W) microemulsion stabilized by a non-ionic surfactant was employed as a pseudo-standard that mimics lipid-bearing microalgal cells suspended in water. The average neutral lipid contents …

Proactive Search: Using Outcome-Based Dynamic Nearest-Neighbor Recommendation Algorithms To Improve Search Engine Efficacy, Christopher Shaun Wagner

Doctoral Dissertations

"The explosion of readily available electronic information has changed the focus of data processing from data generation to data discovery. The prevalent use of search engines has generated extensive research into improving the speed and accuracy of searches. The goal of this research is to accurately predict user behavior as a means to proactively improve speed, accuracy, and predictability of search engines. The proactive approach eliminates query entry time and hence reduces the overall processing time, improving speed. Assuming success, the user locates an electronic resource of interest, improving accuracy.

Algorithms that have been shown to predict many vastly different …

Introduction To Parallel Computation, Clinton Mckay

Graduate Student Theses, Dissertations, & Professional Papers

Introduction to Parallel Computing is a course designed to educate students on how to use the parallel libraries and tools provided by modern operating systems and massively parallel computer graphics hardware.

Using a series of lectures and hands-on exercises. Students will learn about parallel algorithms and concepts that will aid them in analyzing a problem and constructing a parallel solution, if possible, using the tools available to their disposal.

The course consists of lectures, projects, quizzes, and homework. The combination of these components will deliver the necessary domain knowledge to students, test them, and in the process train them to …

Proactive Management Of Pneumonia Epizootics In Bighorn Sheep In Montana, Sarah N. Sells

Graduate Student Theses, Dissertations, & Professional Papers

Pneumonia epizootics are a major challenge for management of bighorn sheep (Ovis canadensis), often causing high mortality and subsequent long-term impacts that may continue for decades. There have been at least 22 epizootics in herds in Montana from 1979‒2013, including 1 that led to a herd’s extirpation, several that appear to be affecting herds up to 3 decades later, and 11 in the last 6 years. The disease is complex and associated risk factors are poorly understood. A lack of tools to help predict and proactively manage risk of pneumonia epizootics in attempt to prevent die-offs has led …

Adaptive Neural Network-Based Optimal Control Of Nonlinear Continuous-Time Systems In Strict-Feedback Form, H. Zargarzadeh, T. Dierks, S. Jagannathan

Electrical and Computer Engineering Faculty Research & Creative Works

This paper focuses on neural network (NN) based optimal control of nonlinear continuous-time systems in strict-feedback form when the system dynamics are known by using an adaptive backstepping approach. A single NN-based adaptive approach is designed to learn the solution of the infinite horizon continuous-time Hamilton-Jacobi-Bellman (HJB) equation while the corresponding optimal control input that minimizes the HJB equation is calculated in a forward-in-time manner without using value and policy iterations. First, the optimal control problem is solved for a generic multi-input and multi-output nonlinear system with a state feedback approach. Then the approach is extended to a single-input and …

Effects Of Crop Residue Burning On Aerosol Properties, Plume Characteristics, And Long-Range Transport Over Northern India, D. G. Kaskaoutis, S. Kumar, D. Sharma, Ramesh P. Singh, S. K. Kharol, M. Sharma, A. K. Singh, Atinderpal Singh, D. Singh

Mathematics, Physics, and Computer Science Faculty Articles and Research

Aerosol emissions from biomass burning are of specific interest over the globe due to their strong radiative impacts and climate implications. The present study examines the impact of paddy crop residue burning over northern India during the postmonsoon (October-November) season of 2012 on modification of aerosol properties, as well as the long-range transport of smoke plumes, altitude characteristics, and affected areas via the synergy of ground-based measurements and satellite observations. During this period, Moderate Resolution Imaging Spectroradiometer (MODIS) images show a thick smoke/hazy aerosol layer below 2-2.5 km in the atmosphere covering nearly the whole Indo-Gangetic Plains (IGP). The air …

Quantum Harmonic Oscillator With Superoscillating Initial Datum, Roman V. Buniy, Fabrizio Colombo, Irene Sabadini, Daniele C. Struppa

Mathematics, Physics, and Computer Science Faculty Articles and Research

In this paper, we study the evolution of superoscillating initial data for the quantum driven harmonic oscillator. Our main result shows that superoscillations are amplified by the harmonic potential and that the analytic solution develops a singularity in finite time. We also show that for a large class of solutions of the Schrodinger equation, superoscillating behavior at any given time implies superoscillating behavior at any other time.

Ensemble Artifact Design For Context Sensitive Decision Support, Shah Jahan Miah, John G. Gammack

All Works

Although an improvement of design knowledge is an essential goal of design research, current design research predominantly focuses on knowledge concerning the IT artifact (tool) design process, rather than a more holistic understanding encompassing the dynamic usage contexts of a technological artifact. Conceptualising a design in context as an "ensemble artifact" (Sein et al., 2011) provides the basis for a more rigorous treatment. This paper describes an IS artifact design framework that has been generated from the development of several practitioner-oriented decision support systems (DSS) in which contextual aspects relevant to practitioners' decision making are considered as integral design themes. …

Trustworthiness Of Web Services, Britto N. Arockiasamy

UNF Graduate Theses and Dissertations

Workflow systems orchestrate various business tasks to attain an objective. Web services can be leveraged to handle individual tasks. Before anyone intends to leverage service components, it is imperative and essential to evaluate the trustworthiness of these services. Therefore, choosing a trustworthy service has become an important decision while designing a workflow system. Trustworthiness can be defined as the likelihood of a service functioning as it is intended.

Selection of a service that satisfies business goals involves collecting relevant information such as security mechanisms, reliability, performance and availability. It is important to arrive at total trustworthiness, which incorporates all of …

A Hybrid Approach To Music Recommendation: Exploiting Collaborative Music Tags And Acoustic Features, Jaime C. Kaufman

UNF Graduate Theses and Dissertations

Recommendation systems make it easier for an individual to navigate through large datasets by recommending information relevant to the user. Companies such as Facebook, LinkedIn, Twitter, Netflix, Amazon, Pandora, and others utilize these types of systems in order to increase revenue by providing personalized recommendations. Recommendation systems generally use one of the two techniques: collaborative filtering (i.e., collective intelligence) and content-based filtering.

Systems using collaborative filtering recommend items based on a community of users, their preferences, and their browsing or shopping behavior. Examples include Netflix, Amazon shopping, and Last.fm. This approach has been proven effective due to increased popularity, and …