Graduate Theses and Dissertations
Permanent URI for this collectionhttps://hdl.handle.net/10877/135
Browse
Browsing Graduate Theses and Dissertations by Department "Engineering Technology"
Now showing 1 - 20 of 70
Results Per Page
Sort Options
Item A Comparison of Epoxy Adhesives to Common Nails as Fastening Methods in Selected Structural Applications of Wood-Frame Construction(1989-05) Brunsting, Amy R.; Crawford, James; Windham, Bill; Batey, AndyThe problem of this study was to experimentally compare the strength upon failure of structural wood joints fastened with epoxy to that of structural wood joints fastened with common nails. The design of this study was a 2 x 5 factorial that included two independent variables, fastening method and joint type. Seven specimen of each joint type were fastened with 3M Scotch-weld 2216 B/A Epoxy and seven specimen of each joint type were also fastened with 16 penny common nails. A Vega Universal Testing Machine was used to measure the maximum joint strength. The data were analyzed using an analysis of variance. An interaction between joint type and fastening method was indicated by the analysis of variance, so Tukey's pairwise comparison was applied to the data to characterize the interaction. This comparison showed that two of the joints were stronger when epoxied, one was stronger when fastened with common nails and two joints showed no significant difference between fastening methods. This study concluded that the method of loading and the joint configuration interacts with the fastening method which indicates that each fastening method may be differentially suited for a particular application.Item A Data-Driven Approach for Reducing Patient Waiting Times in Walk-In Clinics(2017-08) Anandhan, Vivekanand; Perez, Eduardo; Novoa, Clara; Jimenez, JesusWalk-in clinics have grown in popularity in the United States as a substitute for traditional medical care delivered in primary care clinics and emergency rooms. Walk-in clinics offer an affordable option for basic medical services when compared to a hospital emergency room or an urgent care clinic. This type of medical facility simplifies the health care process for many patients with non-life threatening conditions since no previous appointments are required to see a provider. However, the open access nature and lack of patient scheduling can lead to long wait times for patients or long periods of idle time for providers. In this thesis, we derive a discrete-event simulation model to study pure walk-in clinics where patients are served without appointments. In addition, a non-linear programming model is developed to capture the trade-offs between the clinic and patients benefits and costs. A case study is discussed that consider a walk-in clinic located in central Texas. The computational study provides useful insights that are applicable to any walk-in health care facility. For instance, a trade-off between management cost and patient satisfaction can be achieved by proper allocation of resources at each station of the walk-in clinic. Even with various levels of demand (low, normal, and high), it is possible for the clinic to achieve positive results. The analysis provides valuable guidance to clinic administration about allocation of resources to improve patient satisfaction and the overall clinic performance.Item A data-intensive analysis augmented simulation model of an order picking operation(2017-08) Li, Yue; Jimenez, Jesus A.; Perez, Eduardo A.; Méndez Mediavilla, FrancisOrder picking is the most labor-intensive function of distribution centers (DC) in the food and beverage store industry. An efficient order picking process supports this industry’s supply chain to move high volumes of products between the DC and the retail stores. This thesis focuses on the storage location assignment problem to deciding via an algorithm based on Association Rules Mining (ARM) the most adequate location of incoming products. The algorithm analyzes hundreds of orders received by the DC to find correlated products that are ordered frequently together by retail stores. The algorithm then assigns correlated products to storage locations that are close to each other in order to minimize order picking times. The results of computer simulation experiments using data from a real distribution center will be presented to evaluate the performance of the DC layout resulting from ARM.Item A hybrid approach for developing, extending, and implementing industrial maintenance knowledge graphs and semantic ontologies to support smart maintenance diagnostics(2022-12) Tahsin, Renita; Ameri, Farhad; Khaleghian, Meysam; Konur, DincerThe unstructured historical data stored in Computerized Maintenance Management Systems (CMMS) is a mine of maintenance diagnostic information. This data is often underused due to its unstructured and informal nature. This thesis will propose a framework for transforming maintenance log data, which is often in the form of natural language text, into formal knowledge graphs. The proposed method generates a knowledge graph that encodes the semantic relationships between multiple maintenance entities based on the historical data that can be found in maintenance work orders. The knowledge graph is created semi-automatically through the hybrid application of text analytics techniques and human-assisted semantic tagging of maintenance work order text. The semantics of the knowledge graph proposed in this research will be provided jointly by a SKOS thesaurus and an OWL ontology. SKOS (Simple Knowledge Organization System) and OWL (Web Ontology Language) are both Semantic Web standards that will enhance the reusability and portability of the final knowledge graph. The knowledge graph created as an output of a java based tool will become an opensource shared industrial maintenance knowledge base that can be extended incrementally and be used for various decision support applications, including maintenance diagnostics and root-cause analysis. An online knowledge graph platform will be used to conduct querying and inferencing over the graph to support smart maintenance diagnosis.Item A Non-enzymatic Continuous Glucose Monitoring System Using Electrochemical Impedance Spectroscopy(2016-12) Moore, Sean; Song, In-Hyouk; Kim, Namwon; You, Byoung HeeThe following research is a feasibility trial for the development of a continuous glucose monitoring system using electrochemical impedance spectroscopy. Three separate experiments are conducted to determine the effects of electrode surface area on sensing efficacy, the effects of glucose concentration on impedimetric response, and a real time measuring trial of glucose sensing at low, medium, and high concentration levels over a period of fixed frequency and voltage excitation. The resultant data from each of the trials is modeled using electrical equivalent circuits and analyzed via Nyquist and Bode configurations to identify relevant data for each experiment. Results indicate that as electrode surface area increases, the impedimetric response decreases and sensitivity is increased. Deviations throughout the entire glucose range are detected as an inverse of the impedance in the cell due to the inverse relationship of glucose concentration and charge transfer resistance. The continuous monitoring of glucose is demonstrated by a rapid device response over two iterations of glucose concentration in ascending order. As concentration increases, resolution of the impedance signature is reduced suggesting the approach of a saturation set point.Item A Study of Radial Runout For Circular Geometries(2014-08) Lek, Devanda Rex; You, Byoung Hee; Kim, Yoo-Jae; Song, In-HyoukA critical step in geometrical stacking for rotating machinery assembly requires mathematical representation of parts. Vector addition and Least-squares approximation were used to represent a part based on runout. Vector addition yielded a vector representing the net-effect of runout for a feature of a part. Least-squares yielded an approximate location of the physical center-point with respect to the ideal center-point. Representing a part mathematically would be a stepping stone to developing methods of geometrical stacking. Two sets of 8-point runout data was generated to represent the forward and aft of a part. The data and collection was to mimic manual measurement techniques where dial indicators are used. After converting the points to polar form, vector addition and least- squares was applied. Both yielded vectors with angular location where inferences could be made with regards to the physical meaning. For vector addition the resulting vector that represents the positions where runout had the greatest effect over the part. This could have been considered as a high point on the part. Least-squares was more easy to visualize as the vector represented the displaced of the physical center with respect to the ideal center of (0,0). It was noted that the angular locations of both methods were the same but this was due to the calculation methods used for least-square.Item A Study of the Aluminum Industry with an Industrial Arts Study Guide(1972-08) Marshall, Phillip G.; Bowers, Victor L.No abstract prepared.Item Accelerated Carbonation Assessment of High-Volume Fly Ash Concrete(2019-08) Thombare, Omkar H.; Aguayo, Federico; Torres, Anthony; Kim, Yoo-JaeThis investigation deals with determining the effect of 57% relative humidity and 4% CO2 concentration on class C and class F fly ash concrete specimens under accelerated carbonation. Fly ash concrete specimens were differentiated based on the cementitious content (310, 340, 370, and 400 kg/m3) and water-cementitious materials ratio (0.50 and 0.45). The specimens were allowed 1 and 7 days of moist curing and moved to the accelerated carbonation chamber maintained at 57% relative humidity and 4% CO2 ingress. The specimens were tested for carbonation at an age of 28, 56, 63, 70, and 105 days. The accelerated carbonation test results indicate that with addition of supplementary cementitious materials the depth of carbonation also increases. It was evident that increase in the duration of moist curing from 1 day to 7 days had a positive effect, reducing the carbonation depth of control and fly ash concrete mixes. When both types of fly ashes were compared, class C fly ash was observed to be more resistant against carbonation than class F fly ash due to the higher calcium oxide content. Based on the compressive strength results obtained, carbonation depth appeared to decrease with increase in compressive strength, but this correlation was not significant.Item Alkali Silica Reactivity of Blended Class C and Class F Fly Ash Systems(2019-08) Okechi, Ikechukwu K.; Aguayo, Federico; Kim, Yoo-Jae; Torres, AnthonyThis study presents an assessment of the reactivity and performance of blended systems containing Class C and Class F fly ashes, including fly ashes produced from blended coal sources (bituminous and lignite). Seven fly ashes comprising of three Class F and four Class C with varied calcium and alumina content were obtained from Texas and used in this study. The three Class F fly ashes were designated as F1, F2, and F3, while the four Class C fly ashes were designated as C1, C2, C3, and C4. The Class F fly ash F2 was produced from two different coal sources (bituminous and lignite). These fly ashes were tested to ascertain: the heat of hydration when used as partial replacement for cement, ability to improve mechanical properties and mitigate alkali-silica reaction (ASR). Mortar and concrete mixtures were produced. These mixtures involved binary blends of Class C and Class F fly ashes at 20 and 30% cement replacements, and ternary blends at 10/20%, 20/10% and 15/15% cement replacements for Class C and Class F fly ashes respectively. The following test were performend: compressive strength, splitting tensile strength, elastic modulus, drying shrinkage, heat of hydration using isothermal calorimetry, ASR mitigation using the accelerated mortar bar test (ASTM C1260/C1567) and the concrete prism test (ASTM C1293). The long-term durability was also investigated with the use of large concrete exposure blocks. The results of the mechanical property tests showed that the binary and ternary mixtures involving the Class C fly ashes (C2 and C3) and the Class F fly ash (F2) outperformed other fly ashes in improving mechanical properties especially at early age (Day 7). The heat of hydration test results showed that the binary and ternary mixtures of the Class C fly ash C2 and the Class F fly ash F2 generated more heat than that of Class F fly ash F1. Finally, the results of the ASR tests showed that the Class F fly ashes performed better than the Class C fly ashes in mitigating ASR. However, the Class F fly ash F1 was the most effective followed by the Class F Fly ashes F2 and F3. The effect of blending was also observed as the ternary mixtures of the Class C and Class F fly ashes were able to keep expansion within the 0.04% limit at year one in the concrete prism test (ASTM C1293) and large concrete exposure blocks.Item Alkali-silica reaction and delayed ettringite formation in rapid setting hydraulic cementitious systems(2021-08) Velandia, Laura; Aguayo, Federico; Torres, Anthony S.; Shi, XijunThe objective of this thesis is to generate a deeper understanding of how rapid setting and hardening cements perform when being exposed to environments that can hypothetically accelerate or reduce the alkali-silica reaction and delayed ettringite formation. It has been proved in preceding literature studies that ordinary portland cements expands to both coarse and fine aggregates depending on their level of known reactivity. In order to generate precise outcomes for the study of both Calcium Aluminate and Calcium Sulfoaluminate Cements’ reactivity, coarse and fine aggregates identified as non-reactive were utilized. Moreover, concrete exposure blocks were analyzed while exposed to field conditions, and concrete prisms and mortar bars were studied in controlled laboratory conditions. Specimens were studied based on standard and modified testing methods such as ASTM C1293, ASTM C1260, and the Kelham Method.Item Alkaline Activation of Ambient Cured Geopolymer Mortar and Concrete Based on Class C Fly Ash(2015-05) Kotwal, Ashley Russell; Kim, Yoo Jae; Hu, Jiong; Sriraman, VedaramanThe critical element for sustainable growth in the construction industry is the development of alternative cements. A new technological process called geopolymerization provides an innovative solution, and the presence of aluminum and silicon oxides in fly ash has encouraged its use as a source material. To promote the employment of geopolymers for practical concrete applications, the present study investigated the material’s properties, practices and applications. An experimental program was also executed to establish a relationship between the alkaline activator composition and the properties of geopolymer mortar and concrete in fresh and hardened states. Concentrations of sodium hydroxide and sodium silicate were ascertained that are advantageous for constructability and physical properties. Test results indicate that there is potential for the concrete industry to utilize alkaline activated fly ash as an alternative to portland cement in structural building applications.Item An accelerated test method to evaluate cementitious mixtures subjected to chemical sulfate attack(2020-08) Joseph Prabhakar, Sushmitha Mercy; Aguayo, Federico; Kim, Yoo-Jae; Torres, AnthonyNo abstract prepared.Item An Agent-based Model for Supplier Selection in Digital Manufacturing Market(2014-11) Dabbaghianamiri, Maedeh; Ameri, Farhad; Jimenez, Jesus; Sriraman, VedaramanManufacturing supply chain is increasingly becoming agile to keep up with the rapid changes in the market. Agility should be imparted to all aspect of supply chain operation including the formation of supply chain. Ability to assess and select new suppliers quickly is a necessity for rapid formation of supply chains. The Digital Manufacturing Market (DMM) is a virtual market for trading manufacturing services in which buyers and sellers are represented by intelligent software agents. The DMM enables rapid and autonomous deployment of service-oriented supply chains from a pool of suppliers that are distributed geographically. Customer agents in DMM can employ different strategies for selecting the qualified suppliers who possess the required capabilities and capacities. The objective of this research is to compare different decision-making scenarios that customer agents may follow for selecting appropriate suppliers. The metrics used for evaluating different supplier selection scenarios include overall customer wait time and utilization rate of the suppliers in the system. In this work, the agent-based model of DMM is implemented in AnyLogic simulation software in small and large scale. The results show that by having Dynamic Capacity (DC) in the large- scale market, customers find their desired services with less average time while the suppliers are not overloaded.Item An Ontological Approach to Engineering Requirement Representation and Analysis(2015-07) Mukhopadhyay, Alolika; Ameri, Farhad; Sriraman, Vedaraman; Shah, JaymeenThe objective of this research is to develop an ontological method for measuring the information content of engineering design requirements, assessing their completeness and specificity, and automatically classifying them under predetermined classes. Information content can be used as a metric for evaluating the performance of engineering design teams with respect to information generation rate. Requirement plays an important role into idea generation. An incomplete requirement is not useful for a designer and might be misleading and also requirements should be specific or informative enough to efficiently narrow down the design space. A two-step method will be proposed for information content measurement. First, the textual requirements will be converted into an ontological representation and then the information metric will be applied to them. A Java-based tool will be developed for the automated measurement of the information content of requirements based on their ontological representation and proposed metrics. Also ontological reasoning techniques based semantic rules and axioms will be adopted for evaluating completeness and specificity of engineering requirements and classifying them under predefined classes. Multiple experiments will be designed and conducted to validate the proposed methods and metrics.Item Assessment of Current ACI 440.2R-08 Design Guidelines and Evaluation of Hoop Strain in FRP Confined Concrete(2014-08) Ugartechea Garcia, Ana Daniela; Talley, Kimberly G.; Kim, Yoo-Jae; Muniz Solari, OsvaldoStrengthening concrete structures with fiber reinforced polymers (FRP) is becoming increasingly common in construction practice. The currently available design guideline for FRP confined concrete is the ACI 440.2R-08 model for predicting the maximum confined compressive strength. These formulas are based on a modest test dataset of carbon fiber reinforced polymers (CFRP) and a small test dataset of glass fiber reinforced polymers (GFRP) wrapped specimens. This investigation reviewed a meta- analysis of published testing data from CFRP and GFRP-wrapped plain concrete specimens to evaluate the performance of the design guidelines. The results from 694 compression tests are compared to the predicted maximum confined compressive strength following the ACI 440.2R-08 design formulas. The investigation showed that for CFRP- wrapped plain concrete specimens the design formulas work reasonably well, 82% of the values are conservative. However for the GFRP-wrapped specimens, it was found that one third of the tested specimens had capacities that were less than the design guidelines’ prediction. Therefore the current design formula is unconservative for the design of GFRP-wrapped specimens. In order to suggest a conservative design formula, a variation of the existing formula for calculating the confined compressive strength of a GFRP- wrapped specimen is presented. Also, a variation was made for CFRP-confined concrete specimens to make the formula more conservative. Additionally, an investigation of the transfer of strain between FRP layers in FRP confined concrete specimens was completed. Glass fibers were applied to plain concrete specimens, with the number of layers ranging from one to three layers. Strain gages were placed on every layer to perform an analysis of the hoop strains under load. The results showed that the different layers of a GFRP wrap on a specimen do not receive the same amount of strain for the same axial compressive load on the cylinder. This inequality could be a possible explanation for why FRP jackets do not achieve the same tensile strength as the results from tensile coupon tests.Item Assessment of Factors Affecting Fall Accidents Among Construction Workers(2023-08) Kayastha, Rujan; Kisi, Krishna; Ameri, Farhad; Talley, Kimberly GrauThe construction industry is essential for providing employment opportunities and plays a crucial role in the economy of every country worldwide. Despite being a vital sector, it is also one of the most hazardous industries, with fatal and non-fatal injuries occurring frequently due to its unique nature. Falls from height are the deadliest type of accident in the construction industry, accounting for one-third of all fatalities in the industry in the United States. This study investigated the various factors that contribute to falling accidents among construction workers and determined the nature and direction of associations between fall accidents and most predictor variables such as Trade types, Location of Falls, Musculoskeletal pains, Working hour, Age, Safety knowledge, Personal Protective Equipment (PPE), and Sleep hours. Data were collected from workers in different occupations across various construction companies. A quantitative method through SPSS software was used to analyze the data collected from an onsite questionnaire survey based on approved IRB. The objective of the planned research was to examine and evaluate different risk factors and their impact on fall accidents using statistical analysis. The study determined the specific effects of these risk factors on fall accidents and presented the nature and direction of the relationships between them. By doing so, the study offered valuable insights into the development of efficient safety measures to prevent fall accidents in construction industries.Item Capability Language Processing (CLP): Classification and Ranking of Manufacturing Suppliers Based on Unstructured Capability Data(2022-05) Zandbiglari, Kimia; Ameri, Farhad; Shah, Jaymeen; Khaleghian, MeysamIn manufacturing industry, data is available in both structured and unstructured forms. Although the unstructured data represented in natural language text contains valuable information and knowledge, its effective processing for the sake of information retrieval and knowledge extraction is a challenge. Manufacturing Capability data is an example of unstructured data widely used for describing the technological capabilities of manufacturing companies. The objective of this research is to use a set of text analytics techniques to enable automated classification and ranking of manufacturing companies based on their capability narratives available on their websites. For this purpose, a supervised classification method is used in conjunction with semantic similarity measurement method. A formal thesaurus that uses Simple Knowledge Organization System (SKOS) format provides structural and lexical semantics to support classification and ranking. To conduct semantic similarity measurement, edge-based method is combined with Normalized Google Distance (NGD) technique to create a weighted edgebased method for measuring the similarities of manufacturers’ capabilities with the queried capabilities provided by customers. The proposed framework is validated experimentally using a hypothetical search scenario. The results indicate that the generated ranked list is highly correlated with human judgment, especially if the query model and supplier capability model belong to the same class. However, the correlation decreases when multiple overlapping classes of suppliers are mixed. The findings of this research can be used to improve the precision and reliability of Capability Language Processing (CLP) tools and methods and improve the intelligence of supplier discovery and capability mapping platforms.Item Construction Demand Forecasting Based on Conventional and Supervised Machine Learning Methods(2019-05) Ghanbari, Ali; Ameri, Farhad; Mendez Mediavilla, Francis A.; Torres, AnthonyNo abstract prepared.Item Design and Analysis of Capacitive Micromachined Ultrasonic Transducers(2022-05) Howard, Kendalle; Song, In-Hyouk; You, Byoung Hee; Ameri, FarhadCurrently, capacitive micromachined ultrasonic transducers (CMUTs) have emerged as an alternative to the well-established piezoelectric micromachined ultrasonic transducers (PMUTs). The micromachining technology has attracted MEMS researchers to assess the capabilities of CMUT devices to be introduced in various ultrasonic imaging applications. This thesis develops design characterization and simulations for square, hexagon, and circular CMUT cell structures to determine an ideal structure for operating CMUT applications. CMUT cells will be analytically modeled and simulated by Finite Element Modeling (FEM) using COMSOL Multiphysics to highlight the factors influencing the acoustic pressure output maximization. Based on the preliminary results, the hexagon membrane has the highest array packaging density while the more flexible circular membrane has the least amount of stress to operate. This research introduces factors significant for determining the CMUT design for applications with operating frequency ranges of approximately 1.5 MHz.Item Design and optimization of data acquisition system using wireless underground sensor networks(2017-12) Krishnappa, Raghu; Aslan, Semih; Stern, Harold; Stephan, Karl; Koutitas, George; Asiabanpour, BahramThe growth of Wireless Underground Sensor Networks (WUSN) will lead to numerous emerging applications, such as underground pipelines, oil reservoir monitoring, intelligent agriculture, earthquake and landslide forecasting, border patrol, underground mine disaster prevention, and rescue. Underground environments prevent the use of most current wireless communication and networking systems, due to its extremely high attenuation to the propogation of signals, small communication range, and high dynamics of electromagnetic (EM) waves when penetrating through soil, rock, sand, water, crude oil medium and other underground environments. The objective of this research is to address these unique and significant challenges for the realization of wireless sensor networks in underground data monitoring systems. Research also focuses on developing a general framework using underground wireless sensor networks to provide continuous monitoring of pipeline to detect water leakage.