Texas A&M University-Kingsville: AKM Digital Repository
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Experimental study of high-quality CO2 foam stabilized by nanoparticles under high pressure
No full textThe success of a hydraulic fracturing job relies on efficient proppant placement within the fractures for optimum reservoir-to-wellbore connectivity. Effective proppant placement depends on the rheology and proppant carrying capacity of the fracturing fluid (FF). A good FF should maintain sufficient viscosity under harsh reservoir conditions for the duration of the hydraulic fracturing process to support efficient proppant transport. Also, it must have minimal water content to prevent wellbore damage and capillary retention of water by the shales. Other considerations include safety and environmental factors relating to excessive chemical usage and disposal, as well as cost. Carbon dioxide (CO2) foam is the most promising FF due to its minimal water requirement, high viscosity, as well as excellent flow-back potential. However, the problem of foam stability under reservoir conditions exists. There have been many attempts at stabilizing CO2 foams with surfactants, polymers, and nanomaterials (mainly nanoparticles). The nanomaterial approach has so far yielded the best results experimentally. Nanoparticles strongly attach to the gas-liquid interface of the foam. This high adhesion forces, as well as the strength of the nanoparticle used, can help stabilize foams under harsh reservoir conditions.
In this study, the apparent shear viscosity and rheological behavior of nano-SiO2-stabilized CO2 foams were investigated using a flow-loop apparatus. The rheological parameters were estimated using a Power Law model for non-Newtonian fluids. Experiments were conducted at a temperature of 40oC (104oF) and high pressure about 1000 psi. Foam apparent viscosity was measured at different foam qualities (50, 60, 70, 80, and 90%). Under high pressure and 70% foam quality, foam stability was observed through sapphire tube for the different foam configurations. The apparent viscosity of the generated CO2 foams is up to 4.47cp and the foam was stable at 90% foam quality. The effects of shear rates (5837, 8755, and 11674s-1), nanoparticle concentration, and salinity were investigated. The foam systems exhibited shear thinning behavior, and the presence of sodium chloride (NaCl) led to low viscosity foams; particularly at gas qualities above 70%. However, an increase in nanoparticle concentration from 0.5wt% to 1wt% led to improved foam viscosities in the under saline conditions
Economic analysis for irrigation system deployment utilizing Buffel grass crop production
No full textWater is becoming an ever-scarcer resource, it is used not only for human endeavors, but also used in the production of crops for livestock that will directly impact supply chain costs. Many costs occur due to poorly deployed irrigation systems that will not fully utilize land potential and will not produce the proper yield of crops for livestock. A well utilized irrigation system can not only reduce initial set up and maintenance costs but will reduce land waste while increasing yield of dry matter feed for livestock. This research presents a cost benefit analysis approach to determine the economic practicability of installing an irrigation system onto 54 acres of ranch land. This research employs the use of cost benefit analysis and linear programming. Specifically, we examine factors that impact costs and overall production of Buffel grass and cattle. We also compare the production model developed by using linear programming and cost benefit analysis on 54 acres of dedicated ranch land. Based on results obtained, a generalized linear programming model was developed to better understand how this system works on any ranch. This research results indicate that the usage of land is utilized using the optimization technique to maximize the expected profit. This research also found that the profitability of employing an irrigation system is beneficial even when operating at lower production yields when compared to land with no irrigation system
Oligocene Vicksburg formation V-17 reservoir evaluation in the la Rucia North Field, Brooks County, Texas
No full textThe Oligocene Vicksburg Formation V-17 is a highly productive sand reservoir within South Texas. The La Rucia Ranch wells producing the V-17 in Southern Brooks County, Texas have shown high variability in gas, oil, and water volumes. Historical production data show that wells drilled on the west side of the field, tend to be more productive than the wells drilled on the east side; however, there has been no clear cause identified. Previous studies performed using seismic surveys of the study area suggest sand thickness and well location within the heavily faulted structure are the driving controls on productivity, however formation quality was not assessed or discussed.
This study used well data donated by a private oil and gas company, and well data retrieved from a private geologic library. The dataset includes well log files, production statistics, and completion information. The well logs available for the study included gamma ray, spontaneous potential, caliper, deep resistivity, density porosity, neutron porosity, and sonic log data. To validate results in the workflow, I used Archie’s law and the Simandoux, Fertl, and Indonesia models.
The purpose of the study is to identify an appropriate workflow for understanding lithology, calculate shale volume, porosity, water resistivity, water saturation and hydrocarbon saturation. By comparing the shale volume estimate to other wells in the area and reservoir properties to previous studies, we may be able to evaluate reservoir quality.
Preliminary results from log analysis suggests the Vicksburg V-17 interval is a shaly-sandstone. Shale volume based on calculations from the neutron-density curves suggest values around 12 – 20% at the top of the interval and as high as 40 – 50% near the base of the interval. Apparent water resistivity was plotted for hydrocarbon indication. In the water zone, water resistivity was estimated between 0.05 – 0.1 ohm-m. Total porosity and effective porosity were estimated using density porosity and sonic porosity. Finally, water saturation was estimated using a modified Archie empirical equation and modified Simandoux equation, with a, m, and n values established for shaly sands well known in south Texas. Well log interpretations for the Carter Ranch #8 well indicated hydrocarbon saturations averaging 64% in sand zones with >10% shale volume, 15-23% effective porosity, apparent resistivity between 0.14-0.3 ohm-m, and formation water resistivity of 0.074 ohm-m
Predicting bitter peptides from sequence using machine learning techniques
No full textIn this post-genomic era, the prediction of peptide bitterness directly from the sequence is an important element in developing drugs and nutritional studies. Identifying bitter peptides using an experimental method such as in-vivo and in-vitro approaches that include “human taste panel studies” can be arduous, tiresome, time-consuming, and costly. In contrast to the state-of-the-art approaches, this thesis proposes to explore various machine learning techniques specifically, a stacking-based approach for an effective prediction of bitter peptides directly from the peptide sequence. In addition, this work explores various feature encoding and transformation techniques such as Term Frequency-Inverse Document Frequency, K-mers Feature Extraction, and Count Vectorizer. Finally, to validate the robustness, the proposed stacking-based model is compared with the other machine learning algorithms as well as an existing method by utilizing the standard performance evaluation metrics such as Sensitivity, Accuracy, Specificity, and Mathew’s Correlation Coefficient obtained through cross-validation and independent testing
Development of miniature wind energy harvesting systems
No full textA miniature vertical axis wind turbine (VAWT) connected with a miniature power generator could harvest wind energy and provide power to small electronic devices. The objective of this work is to develop a miniature VAWT wind energy harvesting system of a less than 1000 cm3 volume, which utilizes wind from any direction and not be damaged by wind gusts. A series of computational fluid dynamics (CFD) simulations were conducted to study the effect of various blade parameters on the efficiency and output torque of a VAWT. They show that a 2-blade VAWT with thick and long chord length blades is ideal since it can harvest wind energy efficiently and provide enough torque to allow self-starting at low tip speed ratios. With the help of deformable blades, it is possible to make the VAWTs rotate slower and provide less output torque at high wind speeds, reducing the effects of wind gusts. To verify these predictions, multiple VAWT prototypes were 3D printed and tested in a wind tunnel. The test results validate the prediction of CFD simulations, that a VAWT with thicker blades operates more efficiently and provides more torque at low tip speed ratios. Furthermore, VAWTs with deformable blades can self-limit their rotational speeds and output torques when the incoming air flow speed exceeds certain limits. VAWTs with flexure-hinged rigid blades show similar self-limiting behavior and the performance of such VAWTs under high wind speeds can be either improved or reduced depending on the location of stopping tabs. The potential of using a hybrid power generation device that combines piezoelectric effect and electrostatic induction to improve output power was also studied by simulation. Although the additional power captured by electrostatic induction was predicted to be very small, and a hybrid system was not fabricated, the high voltage generated in this process may help improve the overall output power of future hybrid generator.
The current work provides needed guidelines on design principles of largely unexplored miniature wind energy harvesting systems that utilize VAWTs. It shows an innovative passive approach to realize overload protection against wind gusts on a small scale. In the process of developing the miniature wind energy harvesting system, a comprehensive and rigorous test procedure and several test specimen designs were developed to ensure high quality additively manufactured multi-material miniature VAWTs. These new test procedures and test specimen designs will provide comprehensive evaluation on the interfacial bonding strength between rigid and flexible materials in a fused filament fabricated part
Effects of land use, its management and rainfall variability on stormwater runoff in urban, agricultural and mixed-use watersheds
No full textRapid urbanization and increased rainfall pose deleterious impacts on peak flow and water quality in the streams in urban and mixed-use watersheds. The overarching goal of this research is to quantify the effects of land use change and rainfall variability on stormwater runoff and its quality in the urban and mixed-use watersheds. The Stormwater Management Model (SWMM) and the Soil Water Assessment Tool (SWAT) were implemented to estimate the effectiveness of Low Impact Development (LID) strategies to offset the effects of land cover changes and rainfall variability on stormwater runoff and its quality. Both the SWMM and SWAT models were calibrated and validated for flow ( R2 > 0.60 and Nash-Sutcliffe Efficiency - NSE varied from 0.55 to 0.7) and water quality parameters (including Total Phosphorus (TP), Sulphate, and Total Kjeldahl Nitrogen (TKN) in the urban and agricultural watersheds (R2 varied from 0.72 to 0.94). Climate variability played a key role to decrease the two hydrological indices (Unit-area peak discharge and runoff-ratio) in a mixed-use watershed. Reductions in annual rainfall during two five year-periods by 31.5% and 42.9% resulted in decreased the unit-area peak discharge by 35% and 78.7% as well as decreased runoff ratio by 43% and 34.7%, respectively. The modeling results indicated that agricultural development could offset the impacts of urbanization on stormwater runoff under moderate annual rainfall ranging from 84-91.4 cm in a mixed-use semi-arid watershed. However, agricultural development did not cause any significant change in the peak runoff when the total annual rainfall was greater than 100 cm. The LID strategies (green roof (GR) and rain garden (RG)) in a highly urbanized watershed showed 29% reduction in TP, 56% reduction in TKN, 37.5% reduction in total NH4-N, and 98% reduction in SO4 for the rainfall events ranging from 8 cm to 15 cm/day. A 32% reduction in peak flow was estimated under low to moderate rainfall intensities of 2 - 3 cm/day in highly urbanized watershed using green roof (GR) and combined green roof and rain garden (GR+RG). Based on the SWAT model results, Vegetative Filter Strip (VFS) in an agriculture dominated watershed performed better for the total Phosphorus reduction (by 43.4%) than the total Nitrogen (by 32%) reduction. These findings can be used by the city planners and managers to implement various LID strategies and promote agricultural activities to offset the effects of low to moderate rainfall events due to urbanization
A study on forward and inverse kinematics of 6-DOF robot
No full textMulti Degree-of-Freedom (DOF) robots have taken significant roles in the robotization of various industries. They provide significantly more accuracy in performing regular tasks compared to manual work. The robot arms comprise a microcontroller, shoulder, elbow, wrist, and a gripper. Smooth movement in the joints is required for the robot to work with precise and safe operation. An articulated robot was considered for pick and place operations performed in the CoppeliaSim simulator to study the movements. This study provided forward and inverse kinematics calculations, and then simulations were performed to analyze the movements in joints according to time.
The transformation matrices were calculated using the Denavit-Hartenberg convention, and the parameters of Denavit-Hartenberg were assigned according to the robot's kinematic model. Forward kinematics was derived, which was the final transformation matrix, and Inverse kinematics was derived for a given position and orientation of the robot. The third-order cubic polynomial with intermediate points method was used for trajectory. The simulations were performed in CoppeliaSim software with Lua Programming Language, and simulation data was saved as a .csv file for the position, velocity, and accelerations plot analysis
The contributing factors to the academic success of children from single parent households
No full textThere is a significant difference in the number of academically and economically successful people who come from married parents as opposed to those with divorced parents (Jeynes, 2012). The de-stigmatization of divorce that has come in recent times has made it more common and socially acceptable (Abdudulai, 2019). The divorce rate worldwide almost doubled during the four-decade period from 1970 to 2008, increasing from approximately 2.6 to 5.5 divorces per 1,000 married persons in the population (Gale, 2021). Although divorce has become more prevalent, the finding that has been consistent through-out history is that children who come from single-parent households are less likely to find success personally, financially, economically, and educationally (Jeynes, 2012). This study examines the factors that contribute to the success of children. The aim of this text is to identify the negative effects of divorce on children and adults and highlight the contributing factors in an effort to help children who are the most at risk of experiencing the negative effects that some children face when experiencing a life-altering event like divorce. By analyzing previous literature and new, I present the major contributing factors that are useful in developing resources to best assist children to ensure equal opportunities and success for all
Assessment of wind energy resilience in South Texas
No full textMany vital services and infrastructure depend on the stability of power systems for smooth functioning. Extreme weather events due to climate change have disruptive and damaging consequences on power systems. The failure of various forms of energy during the recent winter storm in Texas exposed many faults in the Texas power system and the inability of the aging infrastructure to withstand these extreme weather events. As wind energy is the largest renewable energy source, it is crucial to evaluate the resilience of wind energy in South Texas and the extent to which the resilience of wind energy affects the entire power system in Texas. The failure modes of wind turbine components under extreme weather conditions and their associated cause were identified. This research focused on evaluating the resilience of wind energy under extreme weather conditions in South Texas by developing an evaluation framework to assess wind energy resilience levels using Failure Modes and Effects Analysis (FMEA). Wind turbine components can be updated based on the prevailing weather conditions of a place. Stakeholders can make decisions for prioritization of components based on historical weather data focusing on the frequency of the extreme weather condition and the impact on wind turbine components
The experiences of first-year principals in a title I school
No full textThe expectations and demands of an instructional leader can be overwhelming for a first-year principal. Understanding the complexity of leadership in today's school system and meeting the needs in educating our minority students while working to meet state and federal guidelines is a challenging feat for any principal. This phenomenological study examined the lived experiences of first-year principals in Title I school in South Texas and identified effective strategies necessary to overcome obstacles to meet the demands in this new era of educational leadership. The results of this qualitative method of study brought to light the challenges novice principals face in a leadership role when assigned to a Title I school. Results revealed five significant themes: building relationships, knowing all stakeholders, COVID-19, lack of relevant experiences, and mentorship. Participants highlighted the significance of strong relationships with colleagues and stakeholders as a primary leadership behavior for leading the learning. They further emphasized the value of strong mentorship as imperative to supporting first-year principals. The findings show how to further serve, inform, and provide school districts, administrative programs, and school leadership support teams on how to engage in discussions as to the realities of school leadership experience and the connection between theory and practice. Based on the results, recommendations include how to enhance the foundation to prepare effective campus leaders for the future, extended mentorship, and the value we place on the human factor as a novice principal