Digital Commons Network^™

The Influence Of Self-Efficacy And Working Memory Capacity On Problem Solving Efficiency, Bobby H Hoffman

UNLV Retrospective Theses & Dissertations

The study investigated the influence of self-efficacy beliefs, working memory capacity and problem complexity on problem solving performance, response time, and problem solving efficiency. Previous research investigated these factors from an absolute performance perspective, but not from the perspective of efficiency, defined as the ratio of problem-solving accuracy over time; Students completed an operational span working memory task, rated their self-efficacy for solving multiplication problems without the use of paper or calculation aids, and then solved computer-based cognitive multiplication problems, under conditions of varying complexity. Two competing hypotheses were proposed, which state that the efficiency of problem solving is either …

A Modified Bootstrap Method For Handling Non Detects In Environmental Data, Michelle Melissa Guillaume

UNLV Retrospective Theses & Dissertations

Many samples taken for environmental purposes have concentrations that are measured below the detection limit. Below the detection limit does not mean that there is no concentration present; there may be a concentration present that cannot be accurately measured by the analytical instrument or cannot be determined with 95% confidence that the concentration is greater than zero (EPA, 1989). These concentrations are defined non-detects in the data. When the concentration of the contaminant of concern in a sample falls below the detection limit, it is standard laboratory procedure to represent these data as

An Investigation Of The Kaplan-Meier Upper Confidence Limit For The Population Mean From Environmental Samples With Nondetects, Violeta Graciela Hennessey

UNLV Retrospective Theses & Dissertations

The Kaplan-Meier (K-M) estimator is a non-parametric estimator of the survival function, used in lifetesting and medical follow-up studies where some of the observations are incomplete (right-censored data). In environmental applications, the user is faced with the problem of contaminant concentration falling below the limit of detection (DL) of the instrument (left-censored data). The K-M estimator has recently been proposed in environmental literature for computing the Upper Confidence Limit (UCL) of the mean in the presence of nondetects in environmental data sets. The properties of this UCL, however, have not been investigated. In this thesis, I propose to use Monte …

On Using Block Principal Component Analysis For Reducing Gene-Expression Data Dimensions, Sang Hee Lee

UNLV Retrospective Theses & Dissertations

Since a microarray gene expression database contains a large number of variables and a relatively small number of samples, using and analyzing the databases require an intense, large-dimension computation method. Principal component analysis (PCA) is a useful tool to reduce the number of dimensions, and therefore, the complexity. PCA allows us to analyze the gene expression database with a relatively small data dimension without losing relevant information and increases the analytic visibility of the data. The initial computation using PCA, however, involves calculating a high-dimension covariance or correlation matrix and requires time and hardware resources which are limited in most …

Semi-Active Control Techniques For Shock Isolation, Ganesh B Maganti

UNLV Retrospective Theses & Dissertations

In this thesis the problem of control of semi-active devices (MR damper, MR elastomer) for shock isolation systems are considered. Semi-active control systems combine the best features of both the passive and active control systems, offering the reliability of passive devices, yet maintaining the versatility and adaptability of fully active devices. First the question of stability and control of a two degree-of-freedom magnetorheological (MR) fluid damper shock isolation system is considered. It is shown that for any arbitrarily time varying input current, the system is absolutely stable. This explains the shock isolation capability of the MR damper system even with …

Justifying The Plaintiff's Receipt Of Punitive Damages, Marlisa Moschella

UNLV Retrospective Theses & Dissertations

This thesis addresses the punitive damages reform issue of whether or not the plaintiff should receive the award. Reformers argue the purposes of punitive damages would be better served with other distribution options; and prioritized societal gains, above the gains of the plaintiff. The various purposes of punitive damages show that receipt by the plaintiff is in accordance with original intentions of punitive damages and serves justice. The historical and modern purposes of punitive damages such as vengeance satisfaction, redeeming honor, repairing insult, and supporting 'private attorneys general,' are maintained by the plaintiff receiving damages. These purposes provide an important …

Dorsal And Pectoral Fin Control Of A Biorobotic Autonomous Underwater Vehicle, Mukund Narasimhan

UNLV Retrospective Theses & Dissertations

This thesis involves an in-depth research on the maneuvering of bio-robotic autonomous undersea vehicles (BAUVs) using bio-mimetic swimming mechanisms. Motivation was derived from the amazing flexibility and agility the fish inherit with the help of their pectoral and dorsal fins; In the first part of the thesis, control of BAUVs using dorsal fins is considered. The force produced by the cambering of the dorsal fins is used for control. An indirect adaptive controller is designed for depth tracking along constant trajectories even when the system parameters are not known. Next, for following time-varying trajectories, an adaptive control system for yaw …

Design And Control Of A Smart Fin Using Piezoelectric Actuators, Surya Kiran Parimi

UNLV Retrospective Theses & Dissertations

The objective of this research work is to design and implement control algorithms for smart fin of a projectile, which is currently under development in the Army Research Laboratory (ARL). The smart fin is used to maneuver small aerial vehicles by controlling the rotation angle of the fin. The fin is activated by a composite laminated plate that has two active piezoelectric layers. The prototype of the smart fin is assembled using Macro Fiber Composite (MFC actuator model M8557, Smart Material Co); Control algorithms for rotating the fin when subject to external aerodynamic forces are proposed. These controllers use a …

The Method Of Fundamental Solutions For Solving Wave Equations, Lourdes Jeanette Rivera

UNLV Retrospective Theses & Dissertations

In recent years, the method of fundamental solutions (MFS) has emerged as a novel meshless method in the scientific computing community. In the past, the MFS was essentially restricted to solving homogeneous elliptic equations. Recently, the MFS has gradually extended to solving various types of elliptic and time-dependent problems through the uses of radial basis functions (RBFs); In this thesis, we focus on solving wave equations through the MFS. Currently, there are two major approaches to solve the wave equation: (i) elimination of the time dependence by using the Laplace transform and (ii) discretization in time to approximate the time …

Cfd Modeling Of Compact Offset Strip-Fin High Temperature Heat Exchanger, Sundaresan Subramanian

UNLV Retrospective Theses & Dissertations

This thesis deals with the development of a numerical model to predict the overall performance of an advanced high temperature heat exchanger (HTHX) design, up to 1000°C, for the production of hydrogen by the sulfur iodine thermo-chemical cycle. The present study considers an offset strip-fin type compact high temperature heat exchanger made of liquid silicon impregnated carbon composite (SiC). The ceramic matrix composite material (CMC) is manufactured by impregnating the silicon into the pores of the carbon composites. The prototype heat exchanger is designed to operate at a thermal power of 50 MW. The design is an offset strip-fin, hybrid …

Residual Stress Characterization And Defects Analyses By Microscopy, Subhra Bandyopadhyay

UNLV Retrospective Theses & Dissertations

The structural material to contain the spallation target during transmutation of spent nuclear fuel (SNF) may develop internal stresses resulting from forming operations including plastic deformation and welDing Techniques such as pair-production, activation and life-time analysis based on classical positron annihilation spectroscopy (PAS) have been used to characterize residual stresses in candidate structural materials subjected to cold-reduction, plastic deformation and welDing Since the PAS techniques can only provide qualitative evaluation of residual stress, calibration curves were developed to estimate the resultant residual stress as a function of PAS line-shape parameters. Since plastic deformation can lead to the generation of defects …

Evaluation Of Building Energy Simulation Software Using Residential Homes, Robert Michael Madeja

UNLV Retrospective Theses & Dissertations

Energy simulation software has been widely used by engineers and architects to predict the energy consumption of buildings during the design phase of new construction or remodel. Many of these programs are derived from cooling methodologies developed by ASHRAE. For this study, a widely used software package, Trace 700 was used to see how accurate it can be in predicting the energy consumption of the HVAC (Heating Ventilating and Air Conditioning) system of two residential homes. One home is classified as a Zero Energy Home (ZEH) because it employs advanced construction features which allow it to consume significantly less energy …

Estimation Of Pedestrian Trip Generation Rates In Urban Areas, Pankaj Maheshwari

UNLV Retrospective Theses & Dissertations

This study investigates factors that can be used to quantify average hourly pedestrian trips in urban areas and hence help in estimating pedestrian trips. Various models are developed for morning period, early and late evening periods, and an overall average hourly model was also developed depending on the type of the facilities near the high pedestrian activity locations. General linear regression modeling and other statistical methods are used to identify the significant factors. The best subset regression is used to model four different hourly pedestrian volumes and the F-test is used to support the analysis. The model is validated and …

Adaptive And Variable Structure Control Of A Smart Projectile Fin By Piezoelectric Actuation, Smitha Mani

UNLV Retrospective Theses & Dissertations

The aim of this thesis is to develop efficient control algorithms for the control of a smart projectile fin in the presence of parameter uncertainties and aerodynamic disturbance inputs. The fin can be used to maneuver small aerial vehicles by controlling its rotation angle. The smart fin considered in this thesis consists of a hollow rigid body (or canard) within which a flexible cantilever beam with a piezoelectric active layer is mounted. The beam deforms when voltage is applied to the piezoelectric layer. The rotation angle of the fin is controlled by deforming the flexible beam which is hinged at …

Evaluation Of Pedestrian Countdown Signals In The Las Vegas Metropolitan Area, Kondala Rao Mantri

UNLV Retrospective Theses & Dissertations

An evaluation of the effectiveness of pedestrian countdown signals is presented in this thesis. This is based on an evaluation of the behavior of pedestrians and motorists at selected intersections in the Las Vegas metropolitan area. A series of surveys and pedestrian interviews were used to evaluate the behavior of pedestrians and motorists. Statistical analyses of the data indicated that the countdown signals are able to provide pedestrians valuable information that enhances the safety of the crossing maneuver. The study also indicates that the presence of a countdown timer helps the pedestrians to better understand the meaning of the "Flashing …

An Analysis Of Factors Affecting Net-Migration To Clark County, Scott Charles Mitchell

UNLV Retrospective Theses & Dissertations

Clark County has experienced rapid population growth during the 1990s. The reasons for this rapid growth are a combination of proximity to other population centers, economics, quality of life, and demographic factors. Using OLS and GLS regression methods on pooled time-series county-level data between the years 1990 and 1997, several factors proved to be significantly correlated with the net-migration to Clark County. The most important factors affecting net-migration to Clark County are climate and demographics.

A Gis Based Tool To Determine Optimal Routes, Rajeev Naroor

UNLV Retrospective Theses & Dissertations

Travel in urban and suburban areas is an important activity in an individual's daily time budget. Each trip is preceded by a planning process for selecting a "desirable" or an optimal route from the origin to destination. "Optimal" can take many forms, such as shortest time, shortest distance, least total cost, or safest/most reliable path. Reliable paths are of interest because of the impacts of congestion on travel tomes, and the resultant variability in travel times. A model to help identify optimal travel paths based on travel time variability is developed in this research; Congestion on streets is one of …

Joint Design For Shock Mitigation In Vehicles, Jagannadha Rao Naraparaju

UNLV Retrospective Theses & Dissertations

Propagation of ballistic shock from the region of impact to the locations of critical components can result in human injury and component failure in a combat vehicle, leading to reduced effectiveness of the vehicle and its crew. The armor joints of the ground vehicle can be designed to reduce these possibilities of failure. The objective of the design is to mitigate (absorb/reflect/disrupt, etc.) the incident shock loading and to reduce the acceleration transmitted to specific locations within the vehicle using redesigned joint between structural components that can absorb energy. The purpose of this study is to determine the optimal types …

Handwritten Character Recognition By Combining Multiple Recognizers Using Conditional Probabilities, Mageshkumar Padmanaban

UNLV Retrospective Theses & Dissertations

This research mainly focuses on recognizing the handwritten characters on a form in order to automate the Medical Form processing. Several efficient algorithms have been developed by us so far, to separate the handwritten characters from printed text character; to separate the lines, words and each character. In this thesis, we concentrate on the recognition of the segmented handwritten characters. Different feature recognition algorithms are employed and their performance on a given training set is analyzed. We find a way to combine all these individual feature recognition algorithms by incorporating their interdependence. The reliability of these algorithms is determined in …

Development And Implementation Of A Multilevel High-Pressure Gas Model, Penio Delev Penev

UNLV Retrospective Theses & Dissertations

The development of an accurate hydraulic model of a complex natural gas system is a great challenge for the engineers working to improve an existing system, determining a long-term system expansion or just performing every-day operational studies; This thesis reviews the fundamental concepts of network analysis, equations, solution techniques, model types, and their applicability; Further, the process of developing a multilevel model of a high-pressure natural gas system is described. Emphasis is given on the innovative concepts employed in the model development such as GIS integration, use of actual parameters for more accurate modeling of valves, regulators and compressors, derivation …

Charm City, Victoria Elizabeth Plasse

UNLV Retrospective Theses & Dissertations

Charm City is under construction. It is a space occupied with mutability, free will and perception through physical evidence. This is the ephemeral renovation project of the individual. It is a poetic city trying to articulate what it is to have the rhythms of history and new philosophy manifest into the real. Motion is central to the city and central to the empty space the city has yet to define or occupy. Could Charm City exist outside of America---yes---but the words and sounds would be different. Central to America is motion and central to motion is a guttural voice: an …

Test Preparation Strategies And Test Taking Strategies Use In Chinese High School Students, Yun Peng

UNLV Retrospective Theses & Dissertations

This study investigated the use of test-preparation and test-taking strategies of 429 tenth graders from a key high school in Guangzhou, China. Differences in strategy uses among low-, medium-, and high-achieving groups were determined in two subject-matter areas (Chinese language and mathematics); Instruments used for data collection were the Test Preparation Strategies Questionnaire (TPSQ) and Test Taking Strategies Questionnaire (TTSQ), which examined students' strategy use in cognitive/metacognitive, motivational/emotional, environmental management areas; Results indicated that Chinese tenth graders memorized contents more often than other strategies while preparing for tests. Students planned their course of action for test preparation and selected study …

Estimation Of The Covariance Matrix In Presence Of Non-Detects, Shanmugapriya Saravanan

UNLV Retrospective Theses & Dissertations

Environmental engineers and scientists often encounter trace level concentrations of contaminants that fall below the detection limit (DL) are reported as 'less than DL'. The common method of dealing with non-detects in a multivariate sample is the substitution method in which each observation 'less than DL' is replaced by a suitable value (0, DL/2 or DL) with DL/2 being the recommended method; In this thesis, the applicability of Kaplan-Meier method, which was developed for estimating the survival function in the presence of right censored data, is investigated. Some simulated examples are presented.

An Investigation Of Grid Sampling Schemes For Kriging Contaminant Concentrations In A Riverbed, Matthew Jacob Sokol

UNLV Retrospective Theses & Dissertations

The object of this thesis is to compare grid sampling schemes for the spatial interpolation method of Kriging, specifically when Kriging is used to predict unsampled locations along a riverbed. The main concern will be finding the optimal grid spacing between samples. Kriging uses an estimated spatial covariance matrix, or variogram, to find the best linear unbiased estimate (BLUE) of contamination at an unsampled location. Since the variogram is a measure of covariance as a function of distance between sampled points, it is important to investigate the effect that sampling location distance has on the method of Kriging.

Forever Earth Program: An Overview, Public Lands Institute

Presentations (DM)

• Education
• Scientific studies and research
• Water quality monitoring
• Command post activities

Discover Mojave Outdoor World: Open House, Public Lands Institute

Presentations (DM)

Increase the connection of urban youth to the natural world and our public lands through discovery, recreation, and education.

Assessing “Discover Mojave” Instrument Development And Analysis, Lori Olafson, Gregory Schraw, Jeanne A. Klockow

Reports (DM)

We developed a comprehensive assessment plan and tested the curriculum to determine whether hands-on outdoor recreation events promote knowledge, attitudes, and performance among at-risk urban children. Knowledge, attitude, and performance assessments were developed, refined and conducted through various stages based on cultural and language barriers as well a variety of age groups participating within the events. Findings revealed that knowledge, attitudes, and performance increased substantially as a result of participating in the outdoor recreation events. We conclude that the implementation and assessment of the program is strong. We also make several recommendations for future programs.

Education About The Environment Discover Mojave Programs, Public Lands Institute

Presentations (PLI Education)

Increases people’s knowledge and awareness about the environment and associated challenges, develops the necessary skills and expertise to address the challenges, and fosters attitudes, motivations, and commitments to make informed decisions and take responsible action” (UNESCO, Tbilisi Declaration, 1978)

Science In The Community: A Look At Informal Science Organizations In Clark County, Public Lands Institute

Presentations (PLI Education)

UNLV’s Public Lands Institute is partnering with area-wide Informal Science Organizations to provide experiences that can have significant and lasting impacts on student learning.

Integration Of Service-Learning Into Civil And Environmental Engineering Curriculum, T. C. Piechota, Shashi S. Nambisan

Civil and Environmental Engineering and Construction Faculty Research

Service-learning is defined as integrating the community service experience of students with their academic study so that learning is enhanced. The level of student participation in community service is at an all time high as students feel the need to confront today's technical and societal problems. However, service-learning is more than community service or volunteerism. Service-learning as defined above, integrates the community service experience with the student’s academic study (note the hyphen in "service-learning" means that both are considered equal). This enhances learning which is a fundamental goal of colleges and universities. Boyer highlights the need for service-learning stating that …