Digital Commons Network^™

Single Tower Crane Allocation Models Using Ant Colony Optimization, Carlos Abelardo Treviño

Theses and Dissertations

The construction industry greatly benefits from the utilization of heavy machines and equipment to accomplish successful projects. Tower cranes, in specific, have a crucial role in the transportation of material loads across the site. Because these machines are fixed to the ground, it is essential for planners and managers to position them in a location that provides the most efficient transfer of materials possible. This is commonly known as the tower crane allocation problem, and many researchers have attempted to optimize the tower crane location using mathematical, artificial intelligence, and simulation approaches. However, many works from the literature contain critical …

Enterprise Social Media Use And Impact On Performance: The Role Of Workplace Integration And Positive Emotions, Murad Moqbel, Fiona Fui-Hoon Nah

Information Systems Faculty Publications

Organizations struggle to find ways to improve employees’ performance. To date, little research has empirically examined the relationship between enterprise social media use and knowledge workers’ performance. Using social capital theory and the broaden-and-build theory of positive emotions as our theoretical framework, we investigate the relationship between enterprise social media use and knowledge workers’ performance. We tested our research model by collecting data from employees working for a large information technology firm in the Midwestern United States and analyzing the data using a structural equation modeling approach. The results suggest that enterprise social media use can increase workplace integration, which …

Oxidation Of Dibenzothiophene To Dibenzothiophene-Sufone Using A Molybdenum (Vi) Oxide Catalyst: A Kinetic Study Testing Solvent Dependency And Mole Ratio Efficiency, Tomas Trevino Jr.

Theses and Dissertations

Oxidative desulfurization (ODS) is currently a solution to hydrodesulphurization. Currently, industrial usage of hydrodesulphurization (HDS) is the common source for petroleum purification. Unfortunately, HDS comes with environmental and economical ramifications. Due to the problems and potential hazards being presented with HDS, ODS has become a topic of interest in research development. A kinetic study using molybdenum (VI) oxide as a catalyst was used in oxidative desulfurization. Factors such as mole ratio and solvent dependency were tested for efficiency. As activation energy was calculated to show maximum efficiency with respect to temperature and concentration. Gas Chromatography, FT-IR, and Mass Spectroscopy were …

Remediation Of Lead And Copper Ions From Water Solutions Using Transition Metal Sulfides, Jesus M. Cantu Jr.

Theses and Dissertations

Heavy metal contamination in water solutions has been a major concern since many transition metals don’t play a role in any biological function and are actually detrimental to human health. There have been several techniques that have been implemented for the remediation of heavy metal contaminants. For this project, three metal sulfides—Fe7S8, ZnS, TiS 2—were synthesized and studied for their capabilities to remove Pb(II) and Cu(II) from water solutions. Several parameters were investigated to determine the effects of pH, time, temperature, binding capacities, and interfering ions. The room temperature adsorption capacities ranged 6.23–333.3 mg/g for Pb(II) and 1.31–250 mg/g for …

Study Of Latent Heat Thermal Energy Storage Systems For Concentrated Solar Power Plants, Hermes Chirino

Theses and Dissertations

Concentrated Solar Power (CSP) using phase change material (PCM) as the storage medium in the Thermal Energy Storage (TES) system is a promising technology for large scale utilization of solar thermal energy because heat latent heat thermal energy storage (LHTES) systems can store more energy as the latent heat during the melting process.

This study analyzes the different dimensionless parameters from the 1-D transient enthalpy-based mathematical model used to simulate the heat transfer and flow within the LHTES system. These dimensionless parameters are varied and analyzed with the main objective of increasing thermal energy storage efficiency and exergy efficiency of …

Remediation Of Trivalent And Hexavalent Chromium Ions From Aqueous Solutions Using Titanium Dioxide Polymorphs, Yvette Cantu

Theses and Dissertations

Three titanium dioxide (TiO2) polymorphs were synthesized and used for the removal of chromium (III) and chromium (VI) from aqueous solutions. Various solution parameters were studied to determine the effects of pH, temperature, time, possible interfering ions, and capacities on the binding of Cr(III) and Cr(VI) to all three polymorphs. pH assays determined the optimum pH for the binding of both Cr(III) and Cr(VI) to each polymorph. Adsorption isotherms determined that the adsorption of Cr(III) was non-spontaneous for the three polymorphs with ΔG values ranging from 6.03 to 12.89 kJ/mol. Furthermore, the binding of Cr(VI) to anatase was also non-spontaneous …

Does A Criminal Justice Degree Produce Law Enforcement Officers?, Bryan Keith Murray

Theses and Dissertations

Police departments are being asked to diversify their ranks in a job field dominated by White males. Hispanics are predicted to be the majority-minority by 2043, few studies were conducted to explore whether Hispanic students majoring in criminal justice will pursue a career in law enforcement agencies upon graduation. Therefore, it is necessary and important to investigate the willingness of Hispanic students perusing a career in law enforcement agencies and what kind of factors behind this pursuit. This research anonymously surveyed 203 students currently enrolled in a four-year Hispanic university. Gender and the liberalizing effect served as the independent variables. …

College Readiness Indicators Of First-Generation Hispanic High School Students In South Texas, William Morley

Theses and Dissertations

The purpose of this study was to determine if a relationship exists between first generation Hispanic student participation in an AVID program and college readiness. The dependent variable, college readiness, was measured by passing the Texas Success Initiative (TSI) Reading, Writing, and Math assessment. Predictor variables included Advancement Via Individual Determination (AVID) elective course participation, Advanced Placement courses taken, Advanced Placement Exams taken, Advanced Placement Exams passed, Dual Enrollment Courses Passed, and ACT Composite score. A factor analysis was performed on the predictor variables, resulting in three independent variables for the study: AVID elective course participation, Average of T-scores for …

Synthesis Of Tetraethyl ((2-Amino-1,4-Phenylene)Bis(Methylene)) Bis(Phosphonate): An Intermediate In The Synthesis Of Amino-Substituted Conjugated Materials, Ariel Ivan Torres Burgueno

Theses and Dissertations

Discussed here are the syntheses of the phosphonate precursors for the Wittig-Horner synthesis of poly-phenylene vinylene (PPV) and distyrylbenzene (DSB) derivatives and their respective distyrylbenzene analogs containing amino moieties. The synthesis of the different compounds was achieved through bromination, Michaelis-Arbuzov reaction, reduction of the nitro group with a commercial cobalt sulfide catalyst and sodium borohydride. Preliminary evidence for the synthesis of amino substituted distyrylbenzene and of nitro/alkoxy substituted poly(p-phenylene vinylene) was obtained. Characterization of the products was performed by 1H-NMR. Preliminary results of the synthesis of a novel amino-substituted distyrylbenzene (DSB) are presented. The luminescence of the new DSB was …

Nanoenergetic Gas Generators Based On Metal Hydroxides, Srbuhi Yolchinyan

Theses and Dissertations

The metal oxide based nano thermites have been studied extensively, yet another closely related systems based on metal hydroxides were surprisingly overlooked. For the first time, the thermodynamic calculations using HSC Chemistry-7 and Thermo software, were performed for a collection of 22 novel nano-thermite systems based on aluminum and metal hydroxides, and four representative systems based on bismuth, copper, cerium and nickel hydroxides were characterized using differential scanning calorimeter, scanning electron microscope, and pressure discharge dynamic evaluation. The strongest performance was recorded in Al-Bi(OH)3 system with about 4.9 MPa peak pressure for 0.2 g charge mass. Bismuth oxide and hydroxide …

Ph Effect On The Formation Of Thm And Haa Disinfection Byproducts And Potential Control Strategies For Food Processing, Yen-Con Hung, Brian W. Waters, Veerachandra K. Yemmireddy, Ching-Hua Huang

School of Earth, Environmental, & Marine Sciences Faculty Publications

Chlorine-based sanitizers have seen wide spread use in food sanitation. The reaction of chlorine species with organic matter is a concern for two reasons. Available chlorine can be “used up” by organic compounds resulting in a lower amount of chlorine available for disinfection. Another concern is that some forms of chlorine can react with some organic compounds to form toxic halogenated disinfection byproducts (DBPs). Many studies have been conducted to evaluate the role of hypochlorous acid (HOCl) and hypochlorite ion (OCl−) in the production of DBPs with a particular interest in the production of trihalomethanes (THMs) and haloacetic acids (HAAs). …

Development Of An Innovative Observational Astronomy Class For High School Students In Collaboration With The University Of Texas/Rio Grande Valley, Alan W. Hendrick

Theses and Dissertations

The vision presented by the National Academy of Science Standards is for all students to spend more time ‘doing’ science in order to develop science literacy and be better prepared not only for college but also in understanding and participation in global current events. A course in observational Astronomy is just that, an opportunity for student to “do ‘science by collaborating with actual scientists in real research. The course follows a path in which students learn foundational knowledge and apply this knowledge to complete a successful celestial observation, interpreting the results by making inferences and predictions. This paper begins with …

Variables Relevant To Self-Efficacy: Mexican-American High School Students With Specific Learning Disabilities, Matilde Barrera Alaniz

Theses and Dissertations

The purpose of this study is to ascertain if a relationship exists between self-efficacy and grade point average (GPA), age, gender, language proficiency, socioeconomic status, and failed grade levels during school career among Mexican-American high school students with specific learning disabilities (SLD) residing along the southwestern state of the Mexican border. Moreover, to learn if a relationship exists between motivation and the above variables. This study also observed if a relationship between motivation as measured by the Academic Self-Regulation Questionnaire (SRQ-A) (i.e., external regulation, introjected regulation, identified regulation, and intrinsic motivation) and GPA existed; it also observed the correlation between …

Phylogeography Of An Estuarian Calanoid Copepod; Acartia Tonsa In The Texas Gulf Of Mexico, Nicole J. Figueroa

Theses and Dissertations

The calanoid copepod, Acartia tonsa is one of the most abundant and well-studied estuarian species. However, the idea that this cosmopolitan species has unrestricted dispersal and high gene flow has been challenged. In this study, a more holistic picture of the phylogeography of A. tonsa was developed using the mitochondrial gene cytochrome oxidase one (mtCOI). Multiple new lineages were found in the Texas Gulf of Mexico that are basal to Northeastern Atlantic lineages. Connectivity was also observed between Brazil and the Texas Gulf of Mexico. The revised phylogeny shows a clear pattern of cryptic speciation as the species made a …

Hydrodesulfurization Of Dibenzothiophene Using Lanthanum Doped Comos2, Carolina Valdes Bracamontes

Theses and Dissertations

Hydrodesulfurization (HDS) is a technique used in petrochemical industry for the removal of sulfur from crude oil. Using dibenzothiophene (DBT) as a target molecule and CoMoS2 catalysts doped with various concentrations of lanthanum were studied for catalytic activity in the removal of DBT from solution. Catalysts were synthesized using ammonium tetrathiomolydate, cobalt chloride and lanthanum nitrate under a solvothermal decomposition in decalin at 350 °C with H2 gas at 160 psi. To evaluate decomposition effects, a second set of catalyst precursors were decomposed in a tube furnace at 450 °C under a constant flow of 10%/90% H2/Ar. Characterizations of the …

Functional Predictions Of Microbial Communities In Soil As Affected By Long‐Term Tillage Practices, Janani Hariharan, Aditi Sengupta, Parwinder Grewal, Warren A. Dick

School of Earth, Environmental, & Marine Sciences Faculty Publications

Core Ideas

• Microbial function is important but difficult to assess in soil.
• An omics‐driven tool, PICRUSt, was used to characterize functions of soil microbial communities.
• No‐tillage compared with plow tillage was functionally enriched for most nutrient cycles.
• Many other functions integral to soil health can be explored by the PICRUSt omics approach.

Soil microbial communities affect the soil's biological, chemical, and physical properties, but there is still a knowledge gap regarding the long‐term impact of tillage practices on soil microbial dynamics. Additionally, the accurate identification of belowground microbial functions is a topic of active interest. In this study, microbial community …

The Public’S Perception Of Humanlike Robots: Online Social Commentary Reflects An Appearance-Based Uncanny Valley, A General Fear Of A “Technology Takeover”, And The Unabashed Sexualization Of Female-Gendered Robots, Megan K. Strait, Cynthia Aguillon, Virginia Contreras, Noemi Garcia

Computer Science Faculty Publications

Towards understanding the public’s perception of humanlike robots, we examined commentary on 24 YouTube videos depicting social robots ranging in human similarity – from Honda’s Asimo to Hiroshi Ishiguro’s Geminoids. In particular, we investigated how people have responded to the emergence of highly humanlike robots (e.g., Bina48) in contrast to those with more prototypically-“robotic” appearances (e.g., Asimo), coding the frequency at which the uncanny valley versus fears of replacement and/or a “technology takeover” arise in online discourse based on the robot’s appearance. Here we found that, consistent with Masahiro Mori’s theory of the uncanny valley, people’s commentary reflected an aversion …

A Study Of Perceived Leadership Styles As It Affects The Decision-Making Process Employed By Eleven Catholic School Principals In South Texas, Mary Olivia Agbakoba

Theses and Dissertations

Catholic School principals play an important role in the development of students' spiritual, social, and academic wellbeing. Consequently, in order to improve students' spiritual, social, and academic skill, it is vital to study the perceived leadership styles and decision-making of Catholic School Principals. Research questions include: "Is there a relationship between Catholic School Principals and teachers' perceptions on principals' leadership styles?", and "Is there an association between decision type and decision-making style used?" 11 Catholic School Principals and 179 Catholic School Teachers completed a paper and pencil survey that assessed the perceived leadership styles of principals. Data was analyzed using …

Metasurface-Assisted Phase-Matching-Free Second Harmonic Generation In Lithium Niobate Waveguides, Cheng Wang, Zhaoyi Li, Myoung Hwan Kim, Xiao Xiong, Xi Feng Ren, Guang Can Guo, Nanfang Yu, Marko Lončar

Physics & Astronomy Faculty Publications

The phase-matching condition is a key aspect in nonlinear wavelength conversion processes, which requires the momenta of the photons involved in the processes to be conserved. Conventionally, nonlinear phase matching is achieved using either birefringent or periodically poled nonlinear crystals, which requires careful dispersion engineering and is usually narrowband. In recent years, metasurfaces consisting of densely packed arrays of optical antennas have been demonstrated to provide an effective optical momentum to bend light in arbitrary ways. Here, we demonstrate that gradient metasurface structures consisting of phased array antennas are able to circumvent the phase-matching requirement in on-chip nonlinear wavelength conversion. …

Evolutionary Adaptations Of Biofilms Infecting Cystic Fibrosis Lungs Promote Mechanical Toughness By Adjusting Polysaccharide Production, Kristin Kovach, Megan Davis-Fields, Yasuhiko Irie, Kanishk Jain, Shashvat Doorwar, Katherine Vuong, Numa Dhamani, Kishore Mohanty, Ahmed Touhami, Vernita D. Gordon

Physics & Astronomy Faculty Publications

Biofilms are communities of microbes embedded in a matrix of extracellular polymeric substances, largely polysaccharides. Multiple types of extracellular polymeric substances can be produced by a single bacterial strain. The distinct polymer components of biofilms are known to provide chemical protection, but little is known about how distinct extracellular polysaccharides may also protect biofilms against mechanical stresses such as shear or phagocytic engulfment. Decades-long infections of Pseudomonas. aeruginosa biofilms in the lungs of cystic fibrosis patients are natural models for studies of biofilm fitness under pressure from antibiotics and the immune system. In cystic fibrosis infections, production of the extracellular …

Estimating The Contribution Of Dynamical Ejecta In The Kilonova Associated With Gw170817, B. P. Abbott, R. Abbott, T. D. Abbott, F. Acernese, Teviet Creighton, Mario C. Diaz, Soma Mukherjee, Volker Quetschke, Malik Rakhmanov

Physics & Astronomy Faculty Publications

The source of the gravitational-wave (GW) signal GW170817, very likely a binary neutron star merger, was also observed electromagnetically, providing the first multi-messenger observations of this type. The two-week-long electromagnetic (EM) counterpart had a signature indicative of an r-process-induced optical transient known as a kilonova. This Letter examines how the mass of the dynamical ejecta can be estimated without a direct electromagnetic observation of the kilonova, using GW measurements and a phenomenological model calibrated to numerical simulations of mergers with dynamical ejecta. Specifically, we apply the model to the binary masses inferred from the GW measurements, and use the resulting …

Search For High-Energy Neutrinos From Binary Neutron Star Merger Gw170817 With Antares Icecube And The Pierre Auger Observatory, A. Albert, M. André, M. Anghinolfi, M. Ardid, J. J. Aubert, Teviet Creighton, Mario C. Diaz, Soma Mukherjee, Volker Quetschke, Malik Rakhmanov

Physics & Astronomy Faculty Publications

The Advanced LIGO and Advanced Virgo observatories recently discovered gravitational waves from a binary neutron star inspiral. A short gamma-ray burst (GRB) that followed the merger of this binary was also recorded by the Fermi Gamma-ray Burst Monitor (Fermi-GBM), and the Anti-Coincidence Shield for the Spectrometer for the International Gamma-Ray Astrophysics Laboratory (INTEGRAL), indicating particle acceleration by the source. The precise location of the event was determined by optical detections of emission following the merger. We searched for high-energy neutrinos from the merger in the GeV-EeV energy range using the Antares, IceCube, and Pierre Auger Observatories. No neutrinos directionally coincident …

On The Progenitor Of Binary Neutron Star Merger Gw170817, B. P. Abbott, R. Abbott, T. D. Abbott, F. Acernese, Teviet Creighton, Mario C. Diaz, Soma Mukherjee, Volker Quetschke, Malik Rakhmanov

Physics & Astronomy Faculty Publications

On 2017 August 17 the merger of two compact objects with masses consistent with two neutron stars was discovered through gravitational-wave (GW170817), gamma-ray (GRB 170817A), and optical (SSS17a/AT 2017gfo) observations. The optical source was associated with the early-type galaxy NGC 4993 at a distance of just ∼40 Mpc, consistent with the gravitational-wave measurement, and the merger was localized to be at a projected distance of ∼2 kpc away from the galaxy's center. We use this minimal set of facts and the mass posteriors of the two neutron stars to derive the first constraints on the progenitor of GW170817 at the …

The 13th Data Release Of The Sloan Digital Sky Survey: First Spectroscopic Data From The Sdss-Iv Survey Mapping Nearby Galaxies At Apache Point Observatory, Franco D. Albareti, Carlos Allende Prieto, Andres Almeida, Friedrich Anders, Scott Anderson, Brett H. Andrews, Alfonso Aragón-Salamanca, Maria Argudo-Fernández, Eric Armengaud

Physics & Astronomy Faculty Publications

The fourth generation of the Sloan Digital Sky Survey (SDSS-IV) began observations in 2014 July. It pursues three core programs: the Apache Point Observatory Galactic Evolution Experiment 2 (APOGEE-2), Mapping Nearby Galaxies at APO (MaNGA), and the Extended Baryon Oscillation Spectroscopic Survey (eBOSS). As well as its core program, eBOSS contains two major subprograms: the Time Domain Spectroscopic Survey (TDSS) and the SPectroscopic IDentification of ERosita Sources (SPIDERS). This paper describes the first data release from SDSS-IV, Data Release 13 (DR13). DR13 makes publicly available the first 1390 spatially resolved integral field unit observations of nearby galaxies from MaNGA. It …

Aristotle, Redemption, And The Conquest Of The Americas, Luis Angel Buentello

Theses and Dissertations

The central question addressed in my thesis is the claim that the even though the conquest of the Americas by the Spaniards was a brutal and murderous process, the Spanish imperial project in the Americas, based on Aristotelian ideology, resulted in the most beneficial and least harmful form of conquest conceivable in comparison to the next great empire of the age, the British Empire.

The founding pillars of Spain’s overseas empire in the Americas, based on an Aristotelian framework, produced a synthesis of political thinking that brought about greater benefits to the native populations, and slave populations, subsumed under the …

Wavelet Neural Network Model For Yield Spread Forecasting, Firdous Ahmad Shah, Lokenath Debnath

School of Mathematical & Statistical Sciences Faculty Publications

In this study, a hybrid method based on coupling discrete wavelet transforms (DWTs) and artificial neural network (ANN) for yield spread forecasting is proposed. The discrete wavelet transform (DWT) using five different wavelet families is applied to decompose the five different yield spreads constructed at shorter end, longer end, and policy relevant area of the yield curve to eliminate noise from them. The wavelet coefficients are then used as inputs into Levenberg-Marquardt (LM) ANN models to forecast the predictive power of each of these spreads for output growth. We find that the yield spreads constructed at the shorter end and …

Suspension-Driven Gravity Surges On Horizontal Surfaces: Effect Of The Initial Shape, ‪Nadim Zgheib, T. Bonometti, S. Balachandar

Mechanical Engineering Faculty Publications

We present results from highly resolved direct numerical simulations of canonical (axisymmetric and planar) and non-canonical (rectangular) configurations of horizontal suspension-driven gravity surges. We show that the dynamics along the initial minor and major axis of a rectangular release are roughly similar to that of a planar and axisymmetric current, respectively. However, contrary to expectation, we observe under certain conditions the final extent of the deposit from finite releases to surpass that from an equivalent planar current. This is attributed to a converging flow of the particle-laden mixture toward the initial minor axis, a behaviour that was previously reported for …

Mechanisms Of Chinese Tallow (Triadica Sebifera) Invasion And Their Management Implications – A Review, Lauren S. Pile, G. Geoff Wang, Jeremy P. Stovall, Evan Siemann, Gregory S. Wheeler, Christopher A. Gabler

School of Earth, Environmental, & Marine Sciences Faculty Publications

Ecosystems are under increasing stress from environmental change, including invasion by non-native species that can disrupt ecological processes and functions. Chinese tallow [Triadica sebifera (L.) Small] is a highly invasive tree species in southeastern US forests, prairies, and wetlands, and effectively managing this invasive species is a significant challenge for scientists and land managers. In this review, we synthesize the literature on invasion ecology and management of Chinese tallow. Our review suggests that the invaded range of Chinese tallow is currently limited by dispersal in many areas and by low temperatures and low soil moisture, and by high soil …

The Rider (2017-11-13), Jesus Sanchez

The Rider Archives

Vol.3 No.12

A Class Of Transformations Of A Quadratic Integral Generating Dynamical Systems, Paul Bracken

School of Mathematical & Statistical Sciences Faculty Publications

A class of transformation is investigated which maps a quadratic integral back to its original form but under a redefinition of free parameters. When this process is iterated, a dynamical system is generated in the form of recursive sequences which involve the parameters of the integrand.

The creation of this dynamical system and some of its convergence properties are investigated.

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