Digital Commons Network^™

Modeling Contaminant Behavior In Lake Superior : A Comparison Of Pcbs, Pbdes, And Mercury , Mark D. Rowe

Dissertations, Master's Theses and Master's Reports - Open

A mass‐balance model for Lake Superior was applied to polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and mercury to determine the major routes of entry and the major mechanisms of loss from this ecosystem as well as the time required for each contaminant class to approach steady state. A two‐box model (water column, surface sediments) incorporating seasonally adjusted environmental parameters was used. Both numerical (forward Euler) and analytical solutions were employed and compared. For validation, the model was compared with current and historical concentrations and fluxes in the lake and sediments. Results for PCBs were similar to prior work showing …

Community Managed Rural Water Supply Systems In The Dominican Republic : Assessment Of Sustainability Of Systems Built By The National Institute Of Potable Water And Peace Corps, Dominican Republic , Ryan W. Schweitzer

Dissertations, Master's Theses and Master's Reports - Open

In the Dominican Republic economic growth in the past twenty years has not yielded sufficient improvement in access to drinking water services, especially in rural areas where 1.5 million people do not have access to an improved water source (WHO, 2006). Worldwide, strategic development planning in the rural water sector has focused on participatory processes and the use of demand filters to ensure that service levels match community commitment to post-project operation and maintenance. However studies have concluded that an alarmingly high percentage of drinking water systems (20-50%) do not provide service at the design levels and/or fail altogether (up …

Decentralized Or Centralized Production : Impacts To The Environment, Industry, And The Economy, Abigail R. Clarke-Sather

Dissertations, Master's Theses and Master's Reports - Open

Since product take-back is mandated in Europe, and has effects for producers worldwide including the U.S., designing efficient forward and reverse supply chain networks is becoming essential for business viability. Centralizing production facilities may reduce costs but perhaps not environmental impacts. Decentralizing a supply chain may reduce transportation environmental impacts but increase capital costs. Facility location strategies of centralization or decentralization are tested for companies with supply chains that both take back and manufacture products.

Decentralized and centralized production systems have different effects on the environment, industry and the economy. Decentralized production systems cluster suppliers within the geographical market region …

Hydrogen Applications For Lambert - St. Louis International Airport, Mathew Thomas

Masters Theses

"Today, major airports are facing challenges related to pollution, energy efficiency, and safety and security. Hydrogen and fuel cell technologies, regarded as one of the key energy solutions of the 21st century are more energy efficient and reliable than conventional systems and have the potential to diminish these challenges. These technologies can also play a significant role in reducing the noise, air, and water pollution and enhancing energy security. This paper presents the design of a set of hydrogen technologies and systems that are commercially available and are ready for practical, real-world use. The hydrogen applications selected for Lambert-St. Louis …

Functional Testing Of Faults In Asynchronous Crossbar Architecture, Sriram Venkateswaran

Masters Theses

"The challenge of extending Moore's Law past the physical limits of the present semiconductor technology calls for novel innovations. Several novel nanotechnologies are being proposed as an alternative to their CMOS counterparts, with nanowire crossbar being one of the most promising paradigms. Quite recently, a new promising clock-free architecture, called the Asynchronous Crossbar Architecture has been proposed to enhance the manufacturability and to improve the robustness of digital circuits by removing various timing related failure modes. Even though the proposed clock-free architecture offers several merits, it is not free from the high defect rates induced due to nondeterministic nanoscale assembly. …

Development Of A One Dimensional Subsurface Contaminant Transport Model With Stochastic Applications, Benjamin Waldon Johnson

Masters Theses

"Contaminant source release history is a necessary element of contaminant mass transport simulation in the saturated zone. The source release history is unknown at many sites, and many inverse models have been developed to define finite release histories. To define a likely domain of three source history parameters, a mass balancebased one dimensional approach is developed and tested by discretizing the spatial domain into bands. By incorporating the approach in a spreadsheet model, observed data is represented by both variable length and constant length bands of analysis. Each representation of observed data was tested to determine the most appropriate band …

On-Line Depth Measurement Of Micro-Scale Laser Drilled Holes, Rock Allen Powell

Masters Theses

"A micron-precision micro-hole depth detection scheme has been developed which utilizes a confocal structure and a photomultiplier tube as a photodetector. This scheme is experimentally confirmed to posses an accuracy of greater than 95% for micro-holes on the order of one-hundred microns in diameter and tens of microns in depth and could be easily be integrated for the control of industrial and research oriented laser micro-machining process"--Abstract, page iii.

Adapting Management Strategies To Enter New Global Markets, Karuna Vineetha Vemulapalli

Masters Theses

"With globalization spreading its roots into every country, people from various countries are working together, and will be trying to understand the cultural differences between the organizations in different nations. Effective management of the cultural differences will be an important and competitive advantage. Keeping in mind the different perceptions of the term “Management” by varying cultures, namely United States and India, this research will be focused on understanding and managing these differences.

The proposed research will deal with concepts of cultural diversity, economic differences, intercultural and organizational differences between the two countries. Understanding why some factors like motivation, responsibility, and …

Synthesis Of Best Practices In Transportation Security, Volume I: Vulnerability Assessment, Haritha Reddy Venna, Jon D. Fricker

JTRP Technical Reports

Part I of the research focused on developing a methodology to identify and evaluate the most critical and vulnerable INDOT assets. This method aims at obtaining an index that reflects the vulnerability and criticality of an asset on the basis of multiple performance criteria. This methodology was tested on the seven INDOT districts. Because not all the factors that influence the vulnerability do have same weight, the analytical hierarchical process is used to obtain the weights for the criteria. Countermeasures are suggested as a part of the research to reduce the vulnerability of a given asset based on its relevant …

Cold Plasma Technology: Bactericidal Effects On Geobacillus Stearothermophilus And Bacillus Cereus Microorganisms, Angela D. Morris, Gayle B. Mccombs, Tamer Akan, Wayne L. Hynes, Mounir Laroussi, Susan L. Tolle

Dental Hygiene Faculty Publications

Introduction: Cold plasma, also known as Low Temperature Atmospheric Pressure Plasma (LTAPP) is a novel technology consisting of neutral and charged particles, including free radicals, which can be used to destroy or inactivate microorganisms. Research has been conducted regarding the effect of cold plasma on gram-positive bacteria; however, there is limited research regarding its ability to inactivate the spore-formers Geobacillus stearothermophilus and Bacillus cereus.

Purpose: The purpose of this study was to determine if cold plasma inactivates G. stearothermophilus and B. cereus vegetative cells and spores.

Methods: Nine hundred eighty-one samples were included in this study (762 experimental and …

An Integrated Simulation Environment Combining Process-Driven And Event-Driven Models, Vishnu Sharma Kesaraju

Browse all Theses and Dissertations

A simulation framework that integrates process-driven and event-driven approaches offers a powerful combination of tools to the modeler. In process-driven simulation models, the system can be represented by block diagrams or system networks through which entities flow to mimic real life system objects. In event-driven models, the system can be represented by event graphs, which focus on the abstraction of the event rather than on observable physical entities. In this research, a simulation environment is proposed that integrates both the approaches, i.e. process and event. One of the main outcomes of working in such an environment is that modelers can …

Quantitative Prediction Of Body Surface Potentials From Myocardial Action Potentials Using A Summed Dipole Model, Charles F. Babbs

Weldon School of Biomedical Engineering Faculty Publications

This paper demonstrates quantitatively, using streamlined mathematics, how the transmembrane ionic currents in individual cardiac muscle cells act to produce the body surface potentials of the electrocardiogram (ECG). From fundamental principles of electrostatics, anatomy, and physiology, one can characterize the strength of apparent dipoles along a wavefront of depolarization in a local volume of myocardium. Net transmembrane flow of ionic current in actively depolarizing or repolarizing tissue induces extracellular current flow, which sets up a field of electrical potential that resembles that of a dipole. The local dipole strength depends upon the tissue cross section, the tissue resistivity, the resting …

A Virtual Training Environment For Temporal Bone Surgery, Denis Stack

Theses

A virtual training environment for temporal bone surgery incorporating haptic, visual and audio feedback is presented in this work. Data are derived from Computed Tomography (CT) scans, thus patient-specific cases may be examined in the simulator.

Two main classes of volume haptic algorithm exist for virtual surgery, namely proxy-based and non proxy-based. A review of the evolution of relevant haptic algorithms is presented. Proxy-based and non proxy-based algorithms are implemented and their performance measured against each other by comparison with real-world force data. An improved proxy-based feedback algorithm is also presented. This algorithm uses a spherical proxy which prevents the …

Trunk Response Analysis Under Sudden Forward Perturbations Using A Kinematics-Driven Model, B. Bazrgari, A. Shirazi-Adl, Christian Larivière

Études primaires

No abstract provided.

Spectral Analysis Of Pathological Acoustic Speech Waveforms, Priyanka Medida

UNLV Theses, Dissertations, Professional Papers, and Capstones

Biomedical engineering is the application of engineering principles and techniques to the medical field. The design and problem solving skills of engineering are combined with medical and biological science, which improves medical disorder diagnosis and treatment. The purpose of this study is to develop an automated procedure for detecting excessive jitter in speech signals, which is useful for differentiating normal from pathologic speech. The fundamental motivation for this research is that tools are needed by speech pathologists and laryngologists for use in the early detection and treatment of laryngeal disorders. Acoustical analysis of speech was performed to analyze various features …

Soil Moisture And Water Stage Estimation Using Precipitation Radar, Sumit Puri

UNLV Theses, Dissertations, Professional Papers, and Capstones

In south-western United States, soil moisture data is important for drought studies in the region which is experiencing a drought for many years, whereas in South Florida, water stage data is required by hydrologists to monitor the hydrological flow in wetlands. Soil moisture data and water stage data are not sufficiently available due to sparse monitoring stations. Installation of dense measuring stations over an extended area is costly and labor intensive. Therefore, there is a need to develop an alternative method of measuring soil moisture and water stage. Microwave remote sensing has proven to be a useful tool in the …

Design And Characterization Of A Shock And Vibration Mitigation Seat System, George Samaan Ladkany

UNLV Theses, Dissertations, Professional Papers, and Capstones

Extensive research has been conducted into the development of pneumatic seatbladder systems for shock and vibration mitigation for use in current U.S military vehicle envelopes. This research expands on the previous work through an elaborate experimental characterization of four prototype air bladder seat cushion systems. The experimental characterization conducted included shock testing, continuous vibration, and internal dynamic pressure measured during the shock event.

The shock testing was conducted both at the Army Research Lab as well at UNLV. The shock testing conducted at UNLV was performed on a drop tower designed and constructed during the time of this research. The …

Simulation Study Of Emerging Well Control Methods For Influxes Caused By Bottomhole Pressure Fluctuations During Managed Pressure Drilling, Hakan Guner

LSU Master's Theses

Managed Pressure Drilling (MPD) is an emerging drilling technology that utilizes mud weight, surface backpressure and annular frictional pressure loss (AFP) to precisely control the wellbore pressure. The goal of this project is to identify the most appropriate initial response and kick circulation method for the kicks that result from complications specific to MPD. These complications that can cause a reduction in bottomhole pressure were classified as surface equipment failures and unintended equivalent circulating density (ECD) reductions. Rotating control device (RCD) and pump failures are the examples of surface equipment failures. Pump efficiency loss and BHA position change represent the …

Trusted Querying Over Wireless Sensor Networks And Network Security Visualization, Giovani Rimon Abuaitah

Browse all Theses and Dissertations

Wireless sensor networks (WSNs) as an emerging technology faces numerous challenges. Sensor nodes are usually resource constrained. Sensor nodes are also vulnerable to physical attacks or node compromises. Answering queries over data is one of the basic functionalities of WSNs. Both resource constraints and security issues make designing mechanisms for data aggregation particularly challenging. In this thesis, we first explore the various security techniques for data aggregation in WSNs then we design and demonstrate the feasibility of an innovative reputation-based framework rooted in rigorous statistical theory and belief theory to characterize the trustworthiness of individual nodes and data queries in …

Cellular Function Of The Ia-Motoneuron Circuit Following Peripheral Nerve Regeneration, Katie Leigh Bullinger

Browse all Theses and Dissertations

Successful regeneration of a severed peripheral nerve is insufficient to restore the stretch reflex. This deficit occurs despite successful muscle reinnervation and functional restoration of the circuit components. For example, Ia afferents encode muscle stretch, Ia-motoneuron synapses reform to the extent of restoring low frequency transmission, and activation of motoneurons results in muscle force output. However, when recording intracellularly from reinnervated rat motoneurons during ramp hold and release muscle stretch, no excitatory synaptic potentials are detected in 2/3 motoneurons (Haftel et al., 2005), a clear sign that the synapses connecting Ia afferents with motoneurons are physiologically disrupted. This thesis examines …

Ion Transport Mechanisms During Hyposmotic Regulatory And Isosmotic Apoptotic Volume Decreases In A Human Lens Epithelial Cells Line, Ameet Ajit Chimote

Browse all Theses and Dissertations

Living cells maintain constant volume in response to physiological stresses by altering trans-membrane ion, solute and water flow. In the present study, early and late membrane transport changes in human lens epithelial (HLE-B3) cells under hyposmotic and apoptotic stress were compared. Cell potassium (Ki), rubidium (Rbi)-uptake and water content were measured by atomic absorption spectrophotometry and gravimetry, respectively. Intracellular chloride concentration [Cl]i was determined with the fluorescence dye N- (ethoxycarbonylmethyl)-6-methoxyquinolinium bromide (MQAE), during regulatory volume decrease (RVD) after hyposmotic stress and apoptotic volume decrease (AVD) induced by staurosporine (STP), a protein-kinase inhibitor. Cell water increased in hyposmotic balanced salt solution …

Localization And Surveillance Using Wireless Sensor Network And Pan/Tilt Camera, Pratikkumar U. Desai

Browse all Theses and Dissertations

The ever growing challenges in hostile environments, health care and warzone require accurate indoor localization and surveillance. The de facto localization technique using GPS has poor indoor performance due to the complexity of the indoor environment. Other Radio frequency based indoor localization techniques are unable of accurate localization due to multipath fading.

In this thesis, a system consisting of Cricket wireless sensor motes, a camera and a Pan/Tilt gimbal is proposed to solve the indoor localization and surveillance problems. The system is easy to deploy, is cost effective and gives accurate results. The Crickets motes use the Time Difference of …

Central Mechanisms Regulating Pituitary-Adrenal Activity In Infant Guinea Pigs (Cavia Porcellus) During Exposure To Psychological Stressors: Independent And Combined Effects Of Maternal Separation And Novelty, Deborah Suzanne Maken

Browse all Theses and Dissertations

Separation from the maternal attachment figure, particularly when it occurs in a novel or threatening environment, reliably increases pituitary-adrenal activity in a number of species, and is thought to increase later susceptibility to psychopathology in humans. However, little is known about the central mechanisms mediating these effects. Therefore, I investigated cortisol and ACTH levels in plasma, corticotropin-releasing factor (CRF) mRNA expression in the hypothalamic paraventricular nucleus (PVN), and c-Fos activity in a circuit [medial amygdala (MeA)- bed nucleus of the stria terminalus (BNST)] thought to drive pituitary-adrenal activity during exposure to psychological stressors, as well as in the PVN. Measurements …

Genetic Differentiation In Ambystomatid Salamanders Across A Fragmented Landscape, Joseph E. Bartoszek

Browse all Theses and Dissertations

It is generally recognized that amphibian populations declining across the globe. Habitat loss is the primary cause of decline. The salamander family Ambystomatidae has experienced significantly more rapid decline than the average for amphibians. Coefficients of Conservatism (CoC) have been developed for amphibians in Ohio. These are based primarily on habitat requirements with high CoCs for amphibians with stringent habitat requirements (e.g. vernal pools associated with large, intact, undisturbed forest), and low CoCs for amphibians with less stringent habitat requirements. Genetic diversity in five species and one hybrid complex of ambystomatid salamander in southwest Ohio were examined and compared to …

Identifying Structurally Significant Items Using Matrix Reanalysis Techniques, Bhushan M. Kable

Browse all Theses and Dissertations

Knowledge of critical structural items for an aircraft structural system is crucial for any risk integrated design and maintenance procedure. These critical items are those whose failure can cause catastrophic damage to the entire structure or result in loss of availability. For example, failure of the fuselage longeron of an F-15 aircraft resulted in the separation of the aircraft cockpit from the rest of the structure, resulting in a complete loss of the aircraft. This is clearly a critical structural item that was identified during the design process but did not have appropriate design, manufacturing, or maintenance controls that could …

A Mixed-Dimensionality Modeling Approach For Interaction Of Heterogeneous Steam Reforming Reactions And Heat Transfer, Jeroen Valensa

Master's Theses (2009 -)

Hydrogen is most often produced on an industrial scale by catalytic steam methane reforming, an equilibrium-limited, highly endothermic process requiring the substantial addition of heat at elevated temperatures. The extent of reaction, or conversion efficiency, of this process is known to be heat transfer limited. Scaling the industrial process equipment down to the size required for small, compact fuel cell systems has encountered difficulties due to increased heat losses at smaller scales. One promising approach to effectively scale down the reforming process is to coat the catalyst directly onto the heat exchange surfaces of an integrated reactor/heat exchanger. In this …

Development And Implementation Of Novel Bristle Tool For Surface Treatment Of Metallic Components, Piyush Khullar

Master's Theses (2009 -)

Despite advances in paints and coatings technology, protective coatings are prone to eventual corrosion, degradation and/or failure. Consequently, a corrosive layer will develop that can undermine the performance and integrity of structural components. Therefore, both the corrosive layer and defunct coating must be periodically removed, and an acceptable level of surface cleanliness and texture must be obtained prior to the reapplication of new paint. Currently, an array of processes and equipment are used for efficiently cleaning and conditioning metallic surfaces, such as grit blasting, needle guns, and a variety of non-woven and coated abrasive tools.

This research investigates the method …

Vehicle Positioning Using Image Processing, Armadeep Kaur

Masters Theses

"An imaging-processing approach is described that detects the position of a vehicle on a bridge or similar environment. A load-bearing vehicle must be carefully positioned on a bridge for quantitative bridge monitoring. The personnel required for setup and testing and the time required for bridge closure or traffic control are important management and cost considerations. Consequently, bridge monitoring and inspections are good candidates for smart embedded systems. The objectives of this work are to reduce the need for personnel time and to minimize the time for bridge closure. An approach is proposed that uses a passive target on the bridge …

Using The World Wide Web To Educate And Inform The Public About Risk And Agricultural Biotechnology, Douglas A. Golick, Robert D. Peterson, Leon G. Higley

Department of Entomology: Faculty Publications

The University of Nebraska and AgBios, Inc. launched the AgBiosafety website (http://agbiosaftzy.unl.edu) with the purpose of educating the public about agricultural biotechnology risk and safezy issues through science-based content. This article discusses the creation ofthe website, its components, and data gathered from usage statistics and a web-delivered survey. Also included is a discussion of the results ofdata gathered and recommendations for future web-based educational efforts in biotechnology safety and risk assessment.

Sequencing, Analysis, And Annotation Of Expressed Sequence Tags For Camelus Dromedarius, Abdulaziz M. Al-Swailem, Maher M. Shehata, Faisel M. Abu-Duhier, Essam J. Al-Yamani, Khalid A. Al-Busadah, Mohammed S. Al-Arawi, Ali Y. Al-Khider, Abdullah N. Al-Muhaimeed, Fahad H. Al-Qahtani, Manee M. Manee, Badr M. Al-Shomrani, Saad M. Al-Qhtani, Amer S. Al-Harthi, Kadir C. Akdemir, Mehmet S. Inan, Hasan H. Otu

Department of Electrical and Computer Engineering: Faculty Publications

Despite its economical, cultural, and biological importance, there has not been a large scale sequencing project to date for Camelus dromedarius. With the goal of sequencing complete DNA of the organism, we first established and sequenced camel EST libraries, generating 70,272 reads. Following trimming, chimera check, repeat masking, cluster and assembly, we obtained 23,602 putative gene sequences, out of which over 4,500 potentially novel or fast evolving gene sequences do not carry any homology to other available genomes. Functional annotation of sequences with similarities in nucleotide and protein databases has been obtained using Gene Ontology classification. Comparison to available …