Physical Sciences and Mathematics Commons^™

Rewetting Of Artificially Desiccated Soils: Effect Of Gravity On Vapor-Phase Diffusion, Taylor Arland Ball

UNLV Theses, Dissertations, Professional Papers, and Capstones

Soil desiccation has been suggested as an economically viable alternative for stabilizing water soluble contaminants in deep vadose zones such as at the Hanford Site. This approach would result in a large volume of the vadose zone being dried out in an effort to eliminate the transport mechanism for aqueous phase contaminants. Protecting the top and sides of the desiccated vadose zone from rewetting is a realistic possibility; however, it would be extremely difficult to restrict the upward migration of water from beneath the desiccated zone. One scenario related to the rewetting of the desiccated soil involves the upward migration …

Assessing The Importance Of Nurse Plant Associations To The Growth Of Pre-~Reproductive Yucca Brevifolia, Eric James Chameroy

UNLV Theses, Dissertations, Professional Papers, and Capstones

Facilitation and competition among plant species, in addition to abiotic factors, play an important role in determining plant community structure in arid and semi-arid environments. I conducted a study in Dry Lake Valley, Lincoln County, Nevada, USA to investigate the importance of nurse plant associations to pre-reproductive Yucca brevifolia (Joshua tree). Dry Lake Valley lies within a transition desert between the Mojave and Great Basin Deserts with ecotonal plant communities consisting of species representative of both deserts. A vegetation survey described the communities in which this study was conducted as a Y. brevifolia woodland dominated by an understory of Ephedra …

A Methodology For Evaluating The Strength Of Cued-Recall Graphical Passwords, Mohammad N. Alshehri

Theses and Dissertations

With the revolution of computers, in particular smartphones, people use them to deal with sensitive information such as making online payments, online banking, managing medical records, and communicating with others via messages, emails, and social media. Consequently, computers and smartphones have become a storehouse of private information that must be protected from getting in the hands of unauthorized people. Verifying the identity of a computer’s users before granting access to them is one option of protection. Textual passwords and PINs are commonly used for authentication on standalone PCs, and smartphones. Users create problems, such as using easy to guess passwords …

Detecting Harmful Hand Behavior With Machine Learning From Wearable Motion Sensor Data, Lingfeng Zhang

Theses and Dissertations

In medical care and special needs areas, human activity recognition helps doctors track the patients while they are unsupervised. In this paper, we will present our classifier system for detecting harmful hand behavior. The data comes from a wearable sensor on the user’s wrist. It collects signals in the three axes x, y and z. For each axis, it contains multiple attributes. Because reducing irrelevant attributes can decrease the time complexity and increase the accuracy, we started processing the raw data by ignoring some attributes from the whole attributes set. Our design approach is to apply a classification algorithm which …

Using A Personalized Machine Learning Approach To Detect Stolen Phones, Huizhong Hu

Theses and Dissertations

With the increasing number of smartphone penetration, mining smartphone data that make smartphone smarter became a top research area, there are a lot of event data which we can use to predict behavior or detect anomalies. The privacy disclosure caused by stolen or lost phones becomes an increasingly difficult problem that cannot be ignored. So we design an anomaly detection system by mining patterns to detect stolen phones. We use a pattern mining algorithm to abstract patterns from user past behavior, then construct a personalized model and use a scoring function and threshold setting strategy to detect stolen events. Moreover, …

Contact Resistance To Srruo3 And La0.67Sr0.33Mno3 Epitaxial Films, Mohammad Abuwasib, Hyungwoo Lee, Alexei Gruverman, Chang-Beom Eom, Uttam Singisetti

Alexei Gruverman Publications

Contact resistance to the metallic oxide electrodes, SrRuO₃ (SRO) and La_0.67Sr_0.33MnO₃ (LSMO), is an important parameter that affects the ferroelectric tunnel junction (FTJ) device performance. We have systematically studied the contact resistance between metallic oxide electrodes (SRO, LSMO) and contact metal overlayers (Ti, Pt) after exposure to various processing environments. Specific contact resistivity (ρ_c) for Ti and Pt contact metals and the sheet resistance (R_sh) of the metallic oxides are measured after exposure to different reactive ion plasma process steps. Sheet resistance degradation was observed for both SRO and …

Changes On Cran, Kurt Hornik, Achim Zeileis

The R Journal

New packages in CRAN task views

New contributed packages

Other changes

News From The Bioconductor Project, The Bioconductor Team

The R Journal

The Bioconductor project provides tools for the analysis and comprehension of high throughput genomic data. The 1104 software packages available in Bioconductor can be viewed at http://bioconductor.org/packages/. Navigate packages using ‘biocViews’ terms and title search. Each package has an html page with a description, links to vignettes, reference manuals, and usage statistics. Start using Bioconductor version 3.2 by installing R 3.2.3 and evaluating the commands

The R Journal (December 2015) 7(2): Complete Issue, The R Foundation

The R Journal

Editorial, Bettina Grün

Contributed Research Articles

Fitting Conditional and Simultaneous Autoregressive Spatial Models in hglm, Moudud Alam, Lars Rönnegård, and Xia Shen

VSURF: An R Package for Variable Selection Using Random Forests, Robin Genuer, Jean-Michel Poggi, and Christine Tuleau-Malot

zoib: An R Package for Bayesian Inference for Beta Regression and Zero/One Inflated Beta Regression, Fang Liu, and Yunchuan Kong

apc: An R Package for Age-Period-Cohort Analysis, Bent Nielsen

QuantifQuantile: An R Package for Performing Quantile Regression Through Optimal Quantization, Isabelle Charlier, Davy Paindaveine, and Jérôme Saracco

Numerical Evaluation of the Gauss Hypergeometric Function with the hypergeo Package, Robin K. S. …

Open-Channel Computation With R, Michael C. Koohafkan, Bassam A. Younis

The R Journal

The rivr package provides a computational toolset for simulating steady and unsteady one dimensional flows in open channels. It is designed primarily for use by instructors of undergraduate and graduate-level open-channel hydrodynamics courses in such diverse fields as river engineering, physical geography and geophysics. The governing equations used to describe open-channel flows are briefly presented, followed by example applications. These include the computation of gradually varied flows and two examples of unsteady flows in channels—namely, the tracking of the evolution of a flood wave in a channel and the prediction of extreme variation in the water-surface profile that results when …

Mtk: A General-Purpose And Extensible R Environment For Uncertainty And Sensitivity Analyses Of Numerical Experiments, Juhui Wang, Robert Faivre, Hervé Richard, Hervé Monod

The R Journal

Along with increased complexity of the models used for scientific activities and engineering come diverse and greater uncertainties. Today, effectively quantifying the uncertainties contained in a model appears to be more important than ever. Scientific fellows know how serious it is to calibrate their model in a robust way, and decision-makers describe how critical it is to keep the best effort to reduce the uncertainties about the model. Effectively accessing the uncertainties about the model requires mastering all the tasks involved in the numerical experiments, from optimizing the experimental design to managing the very time consuming aspect of model simulation …

Altopt: An R Package For Optimal Experimental Design Of Accelerated Life Testing, Kangwon Seo, Rong Pan

The R Journal

The R package ALTopt has been developed with the aim of creating and evaluating optimal experimental designs of censored accelerated life tests (ALTs). This package takes the generalized linear model approach to ALT planning, because this approach can easily handle censoring plans and derive information matrices for evaluating designs. Three types of optimality criteria are considered: D-optimality for model parameter estimation, U-optimality for reliability prediction at a single use condition, and I-optimality for reliability prediction over a region of use conditions. The Weibull distribution is assumed for failure time data and more than one stress factor can …

Working With Multilabel Datasets In R: The Mldr Package, Francisco Charte, David Charte

The R Journal

Most classification algorithms deal with datasets which have a set of input features, the variables to be used as predictors, and only one output class, the variable to be predicted. However, in late years many scenarios in which the classifier has to work with several outputs have come to life. Automatic labeling of text documents, image annotation or protein classification are among them. Multilabel datasets are the product of these new needs, and they have many specific traits. The mldr package allows the user to load datasets of this kind, obtain their characteristics, produce specialized plots, and manipulate them. The …

Bsgs: Bayesian Sparse Group Selection, Kuo-Jung Lee, Ray-Bing Chen

The R Journal

An R package BSGS is provided for the integration of Bayesian variable and sparse group selection separately proposed by Chen et al. (2011) and Chen et al. (in press) for variable selection problems, even in the cases of large p and small n. This package is designed for variable selection problems including the identification of the important groups of variables and the active variables within the important groups. This article introduces the functions in the BSGS package that can be used to perform sparse group selection as well as variable selection through simulation studies and real data.

Apc: An R Package For Age-Period-Cohort Analysis, Bent Nielsen

The R Journal

The apc package includes functions for age-period-cohort analysis based on the canonical parametrisation of Kuang et al. (2008a). The package includes functions for organizing the data, descriptive plots, a deviance table, estimation of (sub-models of) the age-period-cohort model, a plot for specification testing, plots of estimated parameters, and sub-sample analysis.

Fitting Conditional And Simultaneous Autoregressive Spatial Models In Hglm, Moudud Alam, Lars Rönnegård, Xia Shen

The R Journal

We present a new version ( 2.0) of the hglm package for fitting hierarchical generalized linear models (HGLMs) with spatially correlated random effects. CAR() and SAR() families for con ditional and simultaneous autoregressive random effects were implemented. Eigen decomposition of the matrix describing the spatial structure (e.g., the neighborhood matrix) was used to transform the CAR/SARrandomeffects into an independent, but heteroscedastic, Gaussian random effect. A linear predictor is fitted for the random effect variance to estimate the parameters in the CAR and SAR models. This gives a computationally efficient algorithm for moderately sized problems.

Distribution And Occurrence Of Bat Species In North Dakota, Josiah J. Nelson, Paul R. Barnhart, Erin H. Gillam

The Prairie Naturalist

Prior to 2009, a detailed survey of occurrence and distribution of bats in North Dakota had not been conducted. Localized surveys, occurrence reports, and museum specimens provided the only records of bats in the state. Ongoing habitat loss, exploitation of natural resources, and the impending spread of white-nose syndrome to the western United States are major threats to bat populations of the region. The objective of this study was to document presence and distributions of bat species resident in North Dakota. From 2009 to 2012, multiple mist-netting and acoustic surveys were conducted to document species presence across North Dakota. A …

Transforming C Openmp Programs For Verification In Civl, Michael Rogers

School of Computing: Dissertations, Theses, and Student Research

There are numerous way to express parallelism which can make it challenging for developers to verify these programs. Many tools only target a single dialect but the Concurrency Intermediate Verification Language (CIVL) targets MPI, Pthreads, and CUDA. CIVL provides a general concurrency model that can represent pro- grams in a variety of concurrency dialects. CIVL includes a front-end that support all of the dialects mentioned above. The back-end is a verifier that uses model checking and symbolic execution to check standard properties.

In this thesis, we have designed and implemented a transformer that will take C OpenMP programs and transform …

Routing Optimization In Interplanetary Networks, Sara El Alaoui

School of Computing: Dissertations, Theses, and Student Research

Interplanetary Internet or Interplanetary Networking (IPN) is envisaged as a space network which interconnects spacecrafts, satellites, rovers and orbiters of different planets and comets for efficient exchange of scientific data such as telemetry and images. IPNs are classified among challenged networks because of the unpredictable changes in the network and the large varying delays in communication. These networks are hard to model using static graphs and do not behave optimally when operated using the standards and techniques of static networks. Delay Tolerant Networking (DTN), in its different implementations, is one of the suggested solutions to overcome these challenges. DTN has …

Quiet-Sun Network Bright Point Phenomena With Sigmoidal Signatures, David L. Chesney, Hakeem M. Oluşeyi, Norton Brice Orange, Patrick R. Champey

Aerospace, Physics, and Space Science Faculty Publications

Ubiquitous solar atmospheric coronal and transition region bright points (BPs) are compact features overlying strong concentrations of magnetic flux. Here, we utilize high-cadence observations from the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory to provide the first observations of extreme ultraviolet quietSun (QS) network BP activity associated with sigmoidal structuring. To our knowledge, this previously unresolved fine structure has never been associated with such small-scale QS events. This QS event precedes a bi-directional jet in a compact, low-energy, and low-temperature environment, where evidence is found in support of the typical fan-spine magnetic field topology. As in active regions …

Simulation Of An Air Cooled Single-Effect Solar Absorption Cooling System With Evacuated Tube Collectors, Mohsen Jahandardoost

UNLV Theses, Dissertations, Professional Papers, and Capstones

Consistently increasing CO2 emission and ozone depletion from synthetic refrigerants are serious environmental issues challenging the scientific community. Absorption cooling systems give scope of utilizing low grade energy source for generating cooling effect. Solar energy is one of these low grade energy sources and with considering the fact that cooling demand increases with the intensity of solar radiation, solar refrigeration has been considered as a logical solution.

This thesis consists of two different simulation stages, in the first stage, a single effect lithium bromide absorption cooling system with constant cooling capacity is modeled and the effect of ambient and generator …

High Pressure X-~Ray Absorption Spectroscopy Studies Of Heavy-~Fermion Cerium And Uranium Compounds, Daniel Antonio

UNLV Theses, Dissertations, Professional Papers, and Capstones

Investigations into f- electron heavy-fermion materials have revealed a wide range of novel behavior. Hydrostatic pressure is a valuable "clean" non-thermal parameter that can be used to systematically study them by tuning their ground state properties. The rare earth compound CeCu2Ge2 shows an unusual two-domed region of unconventional superconductivity under pressure, similar to its isostructural counterpart CeCu2Si2. While the lower pressure dome at about 10 GPa is caused by a magnetic quantum critical point (QCP), the higher one at about 16 GPa is less well understood. Previous structural measurements have indicated that it may be caused by critical valence fluctuations, …

Object Detection And Tracking In Wide Area Surveillance Using Thermal Imagery, Santosh Bhusal

UNLV Theses, Dissertations, Professional Papers, and Capstones

The main objective behind this thesis is to examine how existing vision-based detection and tracking algorithms perform in thermal imagery-based video surveillance. While color-based surveillance has been extensively studied, these techniques can not be used during low illumination, at night, or with lighting changes and shadows which limits their applicability. The main contributions in this thesis are (1) the creation of a new color-thermal dataset, (2) a detailed performance comparison of different color-based detection and tracking algorithms on thermal data and (3) the proposal of an adaptive neural network for false detection rejection.

Since there are not many publicly available …

Generalized Catalan Numbers And Some Divisibility Properties, Jacob Bobrowski

UNLV Theses, Dissertations, Professional Papers, and Capstones

I investigate the divisibility properties of generalized Catalan numbers by ex-

tending known results for ordinary Catalan numbers to their general case. First, I define the general Catalan numbers and provide a new derivation of a known formula. Second, I show several combinatorial representations of generalized Catalan numbers and survey bijections across these representation. Third, I extend several divisibility results proved by Koshy. Finally, I prove conditions under which sufficiently large primes form blocks of divisibility and indivisibility of the generalized Catalan numbers, extending a known result by Alter and Kubota.

Chemical And Electronic Structure Of Surfaces And Interfaces In Cadmium Telluride Based Photovoltaic Devices, Douglas Arthur Duncan

UNLV Theses, Dissertations, Professional Papers, and Capstones

The surface and interface properties are of the upmost importance in the understanding, optimization, and application for photovoltaic devices. Often the chemical, electronic, and morphological properties of the films are empirically optimized, however when progress slows, a fundamental understanding of these properties can lead to breakthroughs. In this work, surfaces and interfaces of solar cell-relevant films are probed with a repertoire of X-ray analytical and microanalysis techniques including X-ray photoelectron (XPS), X-ray excited Auger electron (XAES), X-ray emission (XES) spectroscopies, and atomic force (AFM) and scanning electron (SEM) microscopies.

Silicon-based devices currently dominate the solar market, which is rather inflexible …

Fall Detection By Using Video, Robert J. Gripentog

UNLV Theses, Dissertations, Professional Papers, and Capstones

Cameras have become common in our society and as a result there is more video available today than ever before. While the video can be used for entertainment or possibly as storage it can also be used as a sensor capturing crucial information, The information captured can be put to all types of uses, but one particular use is to identify a fall. The importance of identifying a fall can be seen especially in the older population that is affected by falls every year. The falls experienced by the elderly are devastating as they can cause apprehension to normal life …

Predictive Modeling Of Terrestrial Radiation Exposure From Geologic Materials, Daniel A. Haber

UNLV Theses, Dissertations, Professional Papers, and Capstones

Aerial gamma ray surveys are an important tool for national security, scientific, and industrial interests in determining locations of both anthropogenic and natural sources of radioactivity. There is a relationship between radioactivity and geology and in the past this relationship has been used to predict geology from an aerial survey. The purpose of this project

is to develop a method to predict the radiologic exposure rate of the geologic materials in an area by creating a model using geologic data, images from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), geochemical data, and pre-existing low spatial resolution aerial surveys …

Solving Differential Equations With Least Square And Collocation Methods, Katayoun Bodouhi Kazemi

UNLV Theses, Dissertations, Professional Papers, and Capstones

In this work, we first discuss solving differential equations by Least Square Methods (LSM). Polynomials are used as basis functions for first-order ODEs and then B-spline basis are introduced and applied for higher-order Boundary Value Problems (BVP) and PDEs. Finally, Kansa's collocation methods by using radial basis functions are presented to solve PDEs numerically. Various numerical examples are given to show the efficiency of the methods.

Spreading Speeds And Traveling Waves In Some Population Models., Quancheng Meng

Electronic Theses and Dissertations

Virtually every ecosystem has been invaded by exotic organisms with potentially drastic consequences for the native fauna or flora. Studying the forms and rates of invading species has been an important topic in spatial ecology. We investigate two two-species competition models with Allee effects in the forms of reaction-diffusion equations and integro-difference equations. We discuss the spatial transitions from a mono-culture equilibrium to a coexistence equilibrium or a different mono-culture equilibrium in these models. We provide formulas for the spreading speeds based on the linear determinacy and show the results on the existence of traveling waves. We also study a …

Electrochemical Formation Of One-Dimensional Metal Nanostructures Across Microgaps Electrodes For Resistive Switching And Optical Sensing Applications., Nidhi Shah

Electronic Theses and Dissertations

This dissertation focuses on the electrochemical formation of one-dimensional (1D) Ag nanostructures (in particular nanowires and nanochains) directly on electrode surfaces or gap of two electrodes. Ag nanowires (NWs) and nanorods (NRs) grow directly on glass/indium tin oxide (ITO) surfaces from electrode-attached Au nanoparticle seeds in the presence of cetyltrimethylammonium bromide (CTAB) at appropriate potentials with a 5-15 % yield and the average length ranging from 100 nm to 3 µm for growth times of 30 to 120 min. This method failed when trying to grow Ag NRs/NWs across 5 µm Au electrode gaps. Interestingly, applying voltage in air leads …