Texas A&M University-Kingsville: AKM Digital Repository
Not a member yet
1689 research outputs found
Sort by
Resource recovery and energy demand reduction of a wastewater treatment plant
No full textThe goal of the wastewater treatment industry is evolving from water treatment and protecting public health towards additional goals such as (1) recovering valuable resources, e.g., nutrients and water, (2) recovering chemical and thermal energy, and (3) improving the energy efficiency of the overall process. On this perspective, this dissertation work was carried out with the focus of three major research findings: (1) nutrient recovery from a wastewater treatment plant, (2) removal of a carcinogenic metal (arsenic) from contaminated water, and (3) application of mathematical model to reduce energy demand in wastewater treatment plant. In the case of nutrient recovery research, natural zeolite and modified zeolite (CaO-Z) were used for simultaneous recovery of ammonia and phosphate from belt press filtrate, respectively. Initially, the recovery approach was investigated in the laboratory. Based on the laboratory experiment, the recovery approach was scaled up for bench-scale testing, followed by pilot-scale field testing. It was found that the ammonia-phosphate recovery system of this study can be used to recover more than 88% of ammonia as struvite. Also, about 239 kg struvite could be recovered per 100 m3 of belt press filtrate. In the case of carcinogenic metal removal research, natural zeolite was modified with anhydrous manganese chloride for selective removal of arsenic (III) and arsenic (V). It was found that the modified zeolite (MnO2-Z) can be used to remove at least 40% arsenic regardless of any environmental condition, e.g., pH, initial concentration, and ion species. In the case of optimum pH conditions at pH 9, the modified zeolite can remove almost 99.9% of arsenic (V) at low concentration levels (1 ppb to 25 ppb). In the case of the energy demand reduction research, historical data, and engineering diagrams of Roberto Bustamante Wastewater Treatment Plant were collected to construct a computer-based simulation model of the treatment plant. The computer simulation model was calibration and validated with additional sampling data collected during the summer and winter seasons. Based on the simulation results, it was found that the aeration demand can be reduced by a) modifying primary settling tank scraper design b) adding coagulant at the primary tank, and c) increasing primary settling tank feed flow. If these strategies are implemented at Roberto Bustamante Wastewater Treatment Plant, a yearly aeration energy demand reduction of 2.4 megawatts can be achieved
Sensors in design and control of an autonomous humanoid robot
No full textHumanoid robot “HR-1” is developed at Texas A&M University, Kingsville with range sensors to determine obstacle distance and also touch sensors for robot-object clash detection. Force sensor incorporation also provides feedback of an object’s weight under HR-1 feet or palm. A camera mounted on humanoid robot helps in visual capabilities and processes in addition to a gyro- meter placed at the hip junction to help provide information on the angular velocity relative to three axes. This research presents autonomous humanoid robot HR-1 design and future implementation of several forms of sensors to perceive the world around it. These sensors are quantized, and placed at points on HR-1 based on known properties and expected robot perception. Also, the sensors are connected to a microcontroller which can be interfaced to a computer for environmental data readout and desired future control. This research also presents the model of a sharp infrared (IR) Sensor in Simulink which gives guidelines to setting up other kinds of sensors using the data sheet. An experiment showing a setup of sharp IR sensor and Arduino connection for robot-obstacle distance data acquisition is also displayed
Accelerating maturation of thornscrub habitat for ocelots
No full textLoss of habitat is a major issue contributing to the declining number of ocelots (Leopardus pardalis) in the Lower Rio Grande Valley (LRGV) of Texas, USA. Ocelots within this region are limited to 2 breeding populations, located in Willacy and Cameron Counties, with large areas of land used for urban and agricultural development separating them. The objectives of this project were to test various management techniques on (1) newly-planted, and (2) established thornscrub (thornshrub) plants to identify which treatments were most successful in growing high-quality thornshrub habitat for ocelots as quickly as possible. The first phase of the project involved applying treatments to naturally-growing thornshrub saplings and recording their effects on growth and plant shape over time. Treatments simulated mechanical disturbance on individual plants of 3 species by either (1) clipping plants, (2) mulching plants, or (3) clipping and mulch. Exclosures were placed around 6 plants in each species and treatment combination to determine the impact browsers have on growth and development. In phase II I planted saplings of 7 species that were important components of ocelot habitat, using the same treatments as phase I. Phase I plants saw a significant increase in overall plant growth if they were protected in an exclosure. The shredding, mulching, and combination treatments did not accelerate plant growth. The shredding treatment resulted in smaller plant morphometrics, and mulching did not show any effects. Phase II saplings saw high mortality, most likely caused by excessive browsing. Most of the effects seen with phase II saplings were simple period effects. Plants that did not receive a treatment outperformed plants that received any of the three other treatments. Treatments that were used in this study might be of better use to land managers if they are applied to naturally established plants instead of planted saplings
New methods for efficient results using randomized response sampling
No full textIn this thesis, we will introduce new techniques that will always improve the efficiency of a randomized response model.The Odumade and Singh (2009) model can always be made more efficient than that of Warner (1965), Mangat and Singh (1990), and Kuk (1990). When the new techniques are applied to the Odumade and Singh (2009) estimator, results show that the suggested estimator will always be more efficient. A simulation study, done on SAS, also shows that the suggested estimators are practical and show improvement over the Odumade and Singh (2009) estimator
Estimation of coefficient of dispersion using auxiliary information
No full textIn this thesis, we introduce two new measures of the coefficient of dispersion which we will show have better properties than the existing measures. We next propose a naive estimator of the newly proposed measures of coefficient of dispersion, and find its biases and variance expressions to the first degree of approximation. In the case where an auxiliary variable is available we extend our work to obtain ratio and regression type estimators. Again the bias and variances of the ratio and regression estimators are derived analytically and are compared to the naïve estimator both analytically and empirically. Real data applications are also discussed. R codes for doing simulation studies have also been developed
The impact of water, catechol, and hexafluoroantimonic acid co-catalyts on palladium(II) catalyzed hydroarylation of acetylene
No full textHydroarylation of alkynes has been a reaction of high interest in the field of homogenous catalysis because this process creates a new carbon-carbon bond by direct addition of an arene and an alkyne. This type of reaction is beneficial in synthesis of pharmaceuticals and natural products since it can shorten a multi-step synthetic path. The challenge of this research is to improve the efficiency of the reaction. Previous studies have proven palladium(II) complex catalyst [Pd(PNP)(C2H4)](SbF6)2 and water as co-catalyst as a useful catalytic system. The main goal of this thesis is to increase the TON to more than 100 for the addition of pentamethylbenzene to acetylene as hydroarylation test reaction. First, the standard protocol using 3 equiv of water/ PdII catalyst was re-tested for reproducibility purpose studying the substrate : catalyst ratios of 50:1, 100:1, 150:1, and 200:1. Due to the limits of water, hexafluoroantimonic acid and catechol were studied as alternative co-catalysts. Using ~10 equiv of HSbF6/ PdII catalyst acetylene polymerization was strongly promoted. Catechol was studied using 1, 3, 6 and 9 equiv/ PdII catalyst and showed higher efficiency than water as proton shuttle. The conversion of the reactions was determined by 1H NMR spectroscopy
On unrelated question randomized response techniques
No full textWhen responding to sensitive attributes, there is a tendency for people refuse to respond or to not give trustful answers. Lee, Sedory and Singh (2013) considered estimating proportions of two attributes and their overlap. In this thesis, we consider a new unrelated question model for developing estimators and discuss the bias and variance properties of the proposed estimators. One unrelated model is designed to improving the estimation of the sensitive proportions by combining the proposed unrelated question model with the simple model, and another with the crossed model of Lee et al. (2013). Expressions for variance, bias, and mean square errors of various estimators for different parameters are developed. The Cramer-Rao lower bounds of variance-covariance are computed for the verification of results. In addition, we computed the percent relative efficiency and percent relative protection of the proposed models with the competitors. SAS codes for computing the percent relative efficiency and percent relative protection are also included. At the end, real data applications based on both types of proposed models are included
Sunburn in citrus: assessing physiological impacts and mitigation treatments
No full textThe Lower Rio Grande Valley in southern Texas is subject to high temperatures and drought; major environmental stress factors that limit plant growth, metabolism and productivity. Rising ambient temperatures can cause stress to trees by impacting transpiration, photosynthesis, yield and physiological disorders. Sunburn is a physiological disorder in citrus and other fruit species caused by high light and excess solar radiation. Sunburned fruit is discolored and exhibit varying degrees of cell death. Reflectants can be used to help prevent light and heat damage from solar irradiation which may lead to sunburn. The use of anti-transpirants can limit water loss in times of heat stress. In this study, we evaluated the effects of anti-transpirants and reflectants at different rates and applications on sunburn, yield and fruit quality. Physiological and environmental data were collected for the 2016 and 2017 seasons to determine sunburn incidence, environmental factors that cause tree stress in grapefruit trees. Reflectant sprays reduced fruit and leaf temperatures, while the anti-transpirant treatments increased fruit temperature relative to the untreated control. More sunburn fruit was found in treatments with the anti-transpirant by an increase of 6% and 8.2% for 2016 and 2017 respectively. The reflectant treatment reduced sunburn incidence by 4.9% and 1.8% for 2016 and 2017 respectively. While anti-transpirants led to conditions conductive to sunburn, these negative effects can be mitigated by applying reflectant
Habitat selection and future availability of wintering habitat for sandhill cranes along the Texas coast
No full textCurrent information on sandhill crane (Antigone canadensis) wintering space use and habitat selection along the Texas coast is needed to better understand how land cover change will influence future distribution. Using GPS locations for sandhill cranes (n=40) from 2015–18 along the Texas coast, I investigated space use and habitat selection, then forecasted land change to 2050 using the TerrSet Land Change Modeler. I found cranes wintering in coastal Texas have lower fidelity and larger home ranges compared to other populations. During the day, cranes selected for rice, freshwater emergent wetlands, and flooded grasslands, with higher use of rice in early winter, and wetlands and flooded grasslands later in winter. Flooded grassland and estuarine unconsolidated shore wetlands were selected for roosting habitat, with higher use of estuarine wetlands early in winter and freshwater wetlands later in winter. Forecasted land cover within the central Texas coast for year 2050 showed that suitable habitat will decline by about 22% with declines occurring faster closer to the coast where development is increasing and grasslands are decreasing. This information can be used to help inform land management decisions by identifying areas in which to focus habitat conservation efforts
Prediction of single and competitive adsorption of PFOA, PFOS and Benzene on GAC in drinking water treatment by numerical models
No full textPerfluorooctanoic acid (PFOA), perfluorooctanesulfonic acid (PFOS), and benzene can enter into natural water sources, which are the resources of drinking water. The three substances have been found in human body and can interact with a variety of biomolecules leading to serious health problems. It’s necessary to limit the concentration of these contaminants in drinking water so as to prevent health issues. Granular activated carbon (GAC) with high adsorptive capacity is a promising method to remove contaminants and organic contaminants in water. This research studied the kinetics of removing these contaminants by single adsorption and competitive adsorption on GAC. The adsorption kinetics of single contaminant (PFOA, PFOS, and benzene) on GAC were calculated by Langmuir model and Freundlich model, respectively. The adsorption kinetics of three binary contaminant systems (PFOA/PFOS, PFOA/benzene, and PFOS/benzene) were calculated by Competitive Langmuir Isotherm model and Ideal Adsorbed Solution (IAS), respectively. The experimental data for individual PFOA, PFOS, and benzene adsorption on GAC (20~40 meshes) at a concentration of 1 to 10 mg/L were obtained from the literature. The characteristic parameters and breakthrough curve were predicted. The effects of bed length and cross section area on the adsorption processes were analyzed. The results showed that the breakthrough time increases with increasing bed length and cross section area. The breakthrough for single component and binary systems showed similar trend but the breakthrough time of binary systems was shorter than that of single component adsorption