Engineering Commons^™

Development Of A Dynamic In Vitro Model Of A Stented Blood Vessel To Evaluate The Effects Of Stent Strut Material Selection And Surface Coating On Smooth Muscle Cell Response, Bradley Winn

All Dissertations

Cardiovascular disease is the leading cause of mortality in The United States and Europe, accounting for approximately half of all deaths. The most common form of cardiovascular disease is atherosclerosis, which is characterized by the formation of fatty atheromatous plaques that can grow to occlude the vessel lumen, thus causing ischemia distal to the occlusion. This is commonly treated using balloon angioplasty, which is usually done in conjunction with the deployment of a stent. Stent deployment helps hold the vessel open following the local injury caused by balloon inflation and prevents elastic recoil and subsequent negative remodeling. Stenting has been …

Electrical Coupling Between Micropatterned Cardiomyocytes And Stem Cells, Zhen Ma

All Dissertations

To understand how stem cells functionally couple with native cardiomyocytes is crucial for cell-based therapies to restore the loss of cardiomyocytes that occurs during heart infarction and other cardiac diseases. Due to the complexity of the in vivo environment, our knowledge of cell coupling is heavily dependent on cell-culture models. However, conventional in vitro studies involve undefined cell shapes and random length of cell-cell contacts in addition to the presence of multiple homotypic and heterotypic contacts between interacting cells. Thus, it has not been feasible to study electrical coupling corresponding to isolated specific types of cell contact modes.
To address …

Characterizing Mechanical Heterogeneity In Cardiovascular Cells, Sandra Deitch

All Dissertations

Most tissue-level mechanical models assume homogeneous mechanical properties within a single cell type. However, measurements of cellular mechanical properties show large variability in whole-cell mechanical properties between cells from a single population. This heterogeneity has been observed in many cell populations and with several measurement techniques but the sources are not yet fully understood. Cell mechanical properties are directly related to the composition and organization of the cytoskeleton, which is physically coupled to neighboring cells through adherens junctions and to underlying matrix scaffolds through focal adhesion complexes. As such, we believe that this high level of heterogeneity can be attributed …

Pitch-Based Activated Carbon Fibers: The Effect Of Precursor Composition On Pore Structure, Halil Tekinalp

All Dissertations

Although researchers have previously investigated the effect of precursor differences on the final properties of activated carbon fibers (ACFs), those precursors were not well-characterized. In particular, detailed information about their molecular composition and anisotropy was not available.
In this study, seven oligomeric fractions, each of well-defined composition and molecular weight (mol wt) distribution, were isolated from a commercially produced isotropic petroleum pitch (i.e., Marathon M–50) and used for the production of ACFs. Four of these precursors of varying oligomeric composition were fully isotropic and three contained different levels of mesophase, so that the effects of molecular composition and molecular order …

Evaluating The Use Of Functional Representations For Ideation In Conceptual Design, Benjamin Caldwell

All Dissertations

Functional representations are often used in the conceptual stages of design because they encourage the designer to focus on the intended use and purpose of a system rather than the physical solution. Function models have been proposed by many researchers as a tool to expand the solution search space and guide concept generation, and many design tools have been created to support function-based design. These tools require designers to create function models of new or existing artifacts, but there is limited published research describing what types of functions should be included in a model or the appropriate level of abstraction …

Accelerating Pattern Recognition Algorithms On Parallel Computing Architectures, Kenneth Rice

All Dissertations

The move to more parallel computing architectures places more responsibility on the programmer to achieve greater performance. The programmer must now have a greater understanding of the underlying architecture and the inherent algorithmic parallelism. Using parallel computing architectures for exploiting algorithmic parallelism can be a complex task. This dissertation demonstrates various techniques for using parallel computing architectures to exploit algorithmic parallelism. Specifically, three pattern recognition (PR) approaches are examined for acceleration across multiple parallel computing architectures, namely field programmable gate arrays (FPGAs) and general purpose graphical processing units (GPGPUs).
Phase-only filter correlation for fingerprint identification was studied as the first …

Using Practical Supergain For Passive Imaging With Noise, Martin Siderius

Electrical and Computer Engineering Faculty Publications and Presentations

Recent work has shown that endfire beamforming of ocean noise can be used to produce images of the seabed layering [Siderius et al., J. Acoust. Soc. Am. 120, 1315–1323 (2006)]. This initial noise imaging technique used conventional beamforming and was later extended to adaptive beamforming that is theoretically optimal. However, there can be problems with adaptive methods, which include extreme sensitivity to random errors, the required averaging time, and computational complexity. Here, the concept of supergain is used to show that delay and sum beamforming can produce nearly the same results as the optimal adaptive methods without the drawbacks.

Detection-Assisted Object Tracking By Mobile Cameras, Li He

Department of Electrical and Computer Engineering: Dissertations, Theses, and Student Research

Tracking-by-detection is a class of new tracking approaches that utilizes recent development of object detection algorithms. This type of approach performs object detection for each frame and uses data association algorithms to associate new observations to existing targets. Inspired by the core idea of the tracking-by-detection framework, we propose a new framework called detection-assisted tracking where object detection algorithm provides help to the tracking algorithm when such help is necessary; thus object detection, a very time consuming task, is performed only when needed. The proposed framework is also able to handle complicated scenarios where cameras are allowed to move, and …

A 2-D Processor Array For Massively Parallel Image Processing, Anantha Krishna Nelliparthi

Department of Electrical and Computer Engineering: Dissertations, Theses, and Student Research

The concept of introducing image processing logic within the spatial gaps of an array of photodiodes is the key factor behind the presented work. A two-dimensional massively parallel image processing paradigm based on 8X8 pixel neighborhood digital processors has been designed. A low complexity processor array architecture along with its instruction set has been designed and fully verified on a FPGA platform. Various image processing tests have been run on the FPGA platform to demonstrate the functionality of a design that uses 12 parallel processors. The test results indicate that the architecture is scalable to support high frame rates while …

Location Cheating: A Security Challenge To Location-Based Social Network Services, Mai Ren

School of Computing: Dissertations, Theses, and Student Research

Location-based mobile social network services such as Foursquare and Gowalla have grown exponentially over the past several years. These location-based services utilize the geographical position to enrich user experiences in a variety of contexts, including location-based searching and location-based mobile advertising. To attract more users, the location-based mobile social network services provide real-world rewards to the user, when a user checks in at a certain venue or location. This gives incentives for users to cheat on their locations.

In this thesis, we investigate the threat of location cheating attacks, find the root cause of the vulnerability, and outline the possible …

Concept Tests For A New Wire Flying Vehicle Designed To Achieve High Horizontal Resolution Profiling In Deep Water, Chris Roman, Dave Hebert

Graduate School of Oceanography Faculty Publications

Efficiently profiling the water column to achieve both high vertical and horizontal resolution from a moving vessel in deep water is difficult. Current solutions, such as CTD tow-yos, moving vessel profilers, and undulating tow bodies, are limited by ship speed or water depth. As a consequence, it is difficult to obtain oceanographic sections with sufficient resolution to identify many relevant scales over the deeper sections of the water column. This paper presents a new concept for a profiling vehicle that slides up and down a towed wire in a controlled manner using the lift created by wing foils. The wings …

Determining The Validity Of The Nintendo Wii Balance Board As An Assessment Tool For Balance, Sabrina Mae Deans

UNLV Theses, Dissertations, Professional Papers, and Capstones

Context. Application of the Nintendo Wii-fit balance board and its games have been used in Physical Therapy clinics, showing success in individuals with neurological disorders, and has been recommended as a minimum baseline assessment of a symptoms checklist and standardized cognitive and balance assessments for concussion management by the NCAA. However, it still faces challenges of being considered a reliable and consistent tool for producing normative data in the allied healthcare. Because there is little to no evidence for the Wii-fit balance board as a valid balance assessment tool for clinical and/or research usage, the significance of this study is …

Modeling And Control Of A Flexible Ionic Polymer Metal Composite(Ipmc) Actuator For Underwater Propulsion, Shivakanth Gutta

UNLV Theses, Dissertations, Professional Papers, and Capstones

The goal of this research is to model and control the underwater vehicle propelled by IPMC actuator. IPMC consists of an ionic membrane sandwiched between two metallic electrodes. When an external voltage is applied, IPMC undergoes large deformation due to transport of ions. Due to its ability to work in aqueous environments, it can be used for developing small scale underwater vehicles.

First, Finite element approach is used to describe the dynamics of the both single and segmented IPMC actuator. In the approach presented, each element is attached with a local coordinate system that undergoes rigid body motion along with …

A Study Of A Novel Modular Variable Geometry Frame Arranged As A Robotic Surface, Christopher James Salisbury

UNLV Theses, Dissertations, Professional Papers, and Capstones

The novel concept of a "variable geometry frame" is introduced and explored through a three-dimensional robotic surface which is devised and implemented using triangular modules. The link design is optimized using surplus motor dimensions as firm constraints, and round numbers for further arbitrary constraints. Each module is connected by a passive six-bar mechanism that mimics the constraints of a spherical joint at each triangle intersection. A three dimensional inkjet printer is used to create a six-module prototype designed around surplus stepper motors powered by an old computer power supply as a proof-of-concept example.

The finite element method is applied to …

Fenestration Studies On Building Energy Using The Facade Evaluation Facility, Wendell Cocina

UNLV Theses, Dissertations, Professional Papers, and Capstones

The project was developed to assess several types of facades and their influence on building energy, mainly focused on windows and other building fenestrations. Requirements for the facility are stated in this paper alongside corresponding solutions. The facility is designed to represent a section of a building façade. Experimenting on a wide range of fenestrations including windows with integrated PV elements was the primary prerequisite. The option of removable façade configurations was used and allowed testing specimens to be changed effortlessly. Instrumentation and data acquisition are discussed including calibration and uncertainty analysis. Investigation of the air conditioning unit was concluded …

Hydroclimatic Forecasting In The Western United States Using Paleoclimate Reconstructions And Data-Driven Models, Christopher Allen Carrier

UNLV Theses, Dissertations, Professional Papers, and Capstones

This thesis investigated climate variability and their associated hydrologic responses in the western United States. The western United States faces the problem of water scarcity, where the management and mitigation of available water supplies are further complicated by climate variability. Climate variability associated with the phases of oceanic-atmospheric oscillations has been shown to influence streamflow and precipitation, where predictive relationships have led to the possibility of producing long-range forecasts. Based on literature review, four oceanic-atmospheric oscillation indices were identified in having the most prominent influence over the western United States including the El Niño - Southern Oscillation (ENSO), Pacific Decadal …

Fall Prevention Training And Its Impact To Southern Nevada Construction Workers, Vedaspati Joshi

UNLV Theses, Dissertations, Professional Papers, and Capstones

Death and injury from falls are a long-standing and continuing problem in construction, responsible for at least a third of the construction deaths in the U.S. from 2004 to 2007. Each of those years, Nevada has exceeded the national percentage. Although 29 CFR 1926.503 sets forth Occupational Safety and Health Administration (OSHA)'s requirements that construction employers train employees exposed to fall hazards and document such training, the incidence of deaths and injuries from falls are an indicator that this training was not provided or else was not effective.

Conventional fall protection training is more narrowly focused on recognizing fall hazards …

Modeling Passive Solar Distillation Production In Las Vegas, Nevada, Noe I. Santos

UNLV Theses, Dissertations, Professional Papers, and Capstones

A study has been performed to examine the effects of daily weather on the performance of commercial solar distillation basins (solar stills). The objectives of this study were to evaluate the long term performance of solar stills, to instrument two solar stills and record sub-hourly thermal properties, to evaluate existing heat transfer modeling methods for hourly production, and to create new models to predict daily production using experimental distillate production and local weather data by utilizing artificial neural networks, genetic algorithms, and multivariate regression. A system dynamics model was also created to determine the required basin area and storage volume …