136879 research outputs found
Sort by
Framework for Interactive, Individualized Feedback Design to Improve Thinking Skills in Construction Education
No full textOrganizational improvement relies heavily on having a competent workforce. To facilitate continuous improvement in the construction industry, this study examined the weaknesses in problem-solving skills among today's students (the future workforce). Based on these findings, a new educational approach was proposed, taking today���s student characteristics such as Acquired Attention Deficit Disorder (AADD) into consideration. This proposed educational approach was proved to have immediate and lasting effects beyond class periods on students��� learning through improved thinking skill exercises.
Initial investigations focused on identifying weaknesses in exercising adequate thinking skills in problem-solving and determining the cause beyond the weaknesses. Weaknesses were identified when faced with information processing, locating inputs from multiple sources, repeating the same cognitive processes over extended periods, unfamiliar calculation direction, and ignoring industry common sense due to a calculation-oriented mindset. The lack of fundamentals was identified as the primary cause of the weakness.
To resolve the weaknesses by addressing the cause behind the weaknesses, a new educational approach was proposed and validated through a mixed method. First, a feedback framework was designed which functions for knowledge delivery. Feedback was designed to deliver highly relevant knowledge to the problem at hand and to be presented in a size to allow easy information consumption in real-time considering the target students��� characteristics and learning preferences, Generation Z.
Feedback, a knowledge delivery tool, had immediate effects on exercising thinking skills in problem-solving on a sample of 13 graduate-level students in the Department of Construction Science at Texas A&M University who volunteered for the experiment and the following interview. Especially, two factors of feedback were counted as the key to improving thinking skills, and they are the feedback that was given immediately in real-time when it was in need (when in need) and the feedback that matched the target knowledge in question (what is needed).
The design feedback also had a lasting impact on exercising adequate thinking skills, by which improved academic achievement was demonstrated in a sample of 24 students enrolled in a construction estimating course for undergraduate students at Western Kentucky University. The result of the paired t-test evidenced the effectiveness of feedback on knowledge retention and academic achievement. Additionally, 71% of 24 study participants responded to the self-confidence survey, and the positive self-confidence in exercising thinking skills in each category in Bloom���s Taxonomy also denoted the efficacy of knowledge feeding in feedback.
This study theoretically expanded types of feedback by adding knowledge delivery to the existing feedback types. With this addition, feedback now functions not only giving confirmation or correction for the performance, but it also functions as a vehicle for knowledge delivery. Pragmatically, this study proposed a novel educational approach which aligns with today���s students��� learning preferences and weaknesses
Salmonella Survival, Growth, and Presence in Onion Bulbs, Extracts, and Production Environment
No full textThe purpose of this research was to investigate the presence, survival, and growth of Salmonella in onions and their environment as a prerequisite to understanding the risk that Salmonella poses to the consumer. Extracts from red and white onions grown under blue light significantly (P < 0.05) inhibited the growth of Salmonella. Extracts from genotype 1104 showed an optical density (OD) that was significantly lower than all other extracts, with total inhibition in extracts from the outer scales. Salmonella Newport was inoculated at various depths using a syringe (wounding) in and on red, white, and yellow onions and stored at room temperature for up to 18 days. At intervals, samples were collected from the top layer (skin) and inner layers of each onion and were tested for Salmonella. In all cases, the outer layer of all onion varieties not only inhibited S. Newport growth, but the populations of this pathogen were reduced by 3.2, 2.4, and 2.5 log cycles on red, white, and yellow onions, respectively within the first 3 days of storage, with no significant further changes in counts over 18 days. In contrast, Salmonella Newport grew by 1.7, 2.3, and 2.5 log cycles over the 18-d storage time in the inner layers of red, white, and yellow onions. In the trials to track the presence of Salmonella in onion-producing environments, a total of 255 samples (101 from fields, and 154 from packing plants) were collected and subjected to qualitative and quantitative Salmonella assay in a BAX system with the SalQuant kit. Salmonella was detected in 3 (13%) of 23 samples of well water collected from one onion field, 3 (4%) of 75 samples of soil collected from 3 fields, and 16 (10%) of 151 surface samples collected from 3 onion packing plants. In field samples that tested positive, the quantitative assay gave mean counts of 0.1 log CFU/50 L in water and 1.2 log CFU/g in soil. For environmental samples from packing plants, the mean counts for positive samples ranged between 1.9 and 3.2 CFU/cm2 , no significant differences between types of surfaces were found in the Salmonella counts
Image-Based PV Soiling Quantification and Defect Detection Using Machine Learning
No full textSolar energy, a rapidly growing renewable energy source, has garnered significant global attention in recent years. Achieving high efficiency and maintaining the optimal performance of PV panels is crucial. In addition to the material properties and design of the solar cells, PV efficiency is also significantly affected by system losses and degradation.
Soiling loss, an important system loss, cannot be improved solely through design modifications and requires periodic inspection and cleaning. In this thesis study, a novel image-based method for estimating soiling loss has been proposed, utilizing key feature extraction and linear regression techniques. Two datasets were collected for this purpose: an in-lab simulation dataset and a dataset obtained from an outdoor PV testing field. The proposed method was tested with both datasets using measured soiling loss/power loss as a gold standard. The method achieved an r-squared value of 0.98 and the root mean squared error of 0.01, which showed its significant potential for cost-effective soiling monitoring purposes.
In addition to soiling loss, this study also addresses the problem of PV cell defects, which can come from degradation. A computer vision-based method is developed for detecting PV defects. The method utilized the State-of-the-Art (SOTA) object detection algorithm You Look Only Once V8 (YOLOV8), with U-net architecture and feature pyramid network to improve the accuracy. In addition, the model is compressed with Layer-Adaptive Magnitude-based Pruning to improve the computational efficiency, Additional improvement including the adoption of a better loss function inner-CIoU and the activation function MiSH. To test the proposed method, an open-source Electroluminescent PV defect dataset PVEL-AD was used. The method is compared with several existing algorithms in terms of accuracy and efficiency. The proposed method outperformed all reported work in accuracy and ranked No.2 only in efficiency. It reached mean Average Precision under IoU of 50% (mAP50) of 93.1%, and mean Average Precision under IoU from 50% to 95% (mAP50:95) of 68.7%, which improved about 8-15% comparing to the best existing algorithm. The model���s detection speed is 85.3 Frame per Second (FPS) which ranked in 2nd place among all the existing works. In addition, the model is trained on multiclass detection, the fastest method with FPS of 94.34 only trained on selected classes.
In summary, the novel methods developed in this thesis provide effective tools for estimating soiling loss and detecting defects in PV panels. With improved efficiency and accuracy, these developments have the potential to significantly improve the overall efficiency and maintenance of solar energy systems
Theory and Applications of Mixed-Integer Fractional Programming
No full textThis dissertation is focusing on developing theoretical and practical results for a class of mixed-integer problems with fractional objectives. We introduce the generalized clique relaxation models with fractional objectives, namely the maximum ratio s-plex problem and the maximum ratio s-defective clique problem. We establish complexity results, describe solution methods, as well as introduce valid inequalities that are shown to substantially improve the performance of the proposed formulations. Then we we discuss the application of Bron-Kerbosh algorithm for solving fractional clique relaxation problems. We develop a new efficient combinatorial approach best suitable for sparse graphs. Finally, propose an extension of knapsack problems with fractional objectives arising from applications in service systems design and facility location problems with congestion
The Role of Metformin in the Prevention and Treatment of Breast Cancer: Insights From Preclinical Studies
No full textMetformin, a commonly used medication for type II diabetes, has been reported to decrease breast cancer risk. However, results from observational and clinical trials show mixed results, questioning the efficacy of metformin for breast cancer treatment. In addition, determining what patient populations may experience optimal responses to the drug is warranted. Our goal was to improve our understanding of the circumstances under which metformin may exhibit maximal efficacy for breast cancer prevention and treatment. First, we assessed the effectiveness of metformin on tumor outcomes in ovary-intact and ovariectomized rodents. Our findings support metformin treatment being more effective in the postmenopausal setting, having observed prevention of new tumors and reduced tumor burden. The second objective was to elucidate how metformin affects mammary adipose tissue. We have previously shown that metformin reduces M2-like aromatase-expressing macrophages in the tumor border. Here, we investigated if treatment lowered inflammatory markers in tumor-distant mammary tissue. We found a small reduction in inflammatory markers in metformin-treated mammary adipose. However, RNA seq analysis from adipose tissue from treated and control rats showed no changes in gene expression. Our final aim centered on determining the optimal timeframe for metformin treatment during the menopause transition for improved tumor outcomes. We found that metformin treatment in the first four weeks post-ovariectomy was needed to improve tumor outcomes. This work underscores the significance of menopausal status and timing within the menopause transition in influencing the efficacy of metformin for treating mammary tumors and emphasizing the need for a targeted approach to metformin treatment for breast cancers
Multi-Physics Modeling and Simulations of Heat Pipe Cooled Graphite Moderated Micro Reactor
No full textHeat pipe micro reactors are compact, innovative nuclear reactors that utilize heat pipe technology to manage heat transfer efficiently. The advantage of heat pipe micro reactors lies in their reduced complexity, high efficiency, and ability to provide stable power in various scenarios where traditional, larger reactors are not feasible or practical. This research presents a multi-physics analysis focusing on a proposed design of 0.5 MWth heat pipe cooled, graphite moderated nuclear micro reactor. The main driver of the design study was to achieve enhanced safety characteristics, while maintaining long core lifetime and excellent power producing capabilities. The envisioned outcome was a versatile design adaptable to various purposes including remote locations and space applications.
In order to assess the safety characteristics of the design, investigations of the main reactor parameters were performed through developing a multi-physics tool, that included a neutronic model, point kinetics model, thermal conduction model, heat pipe model, and mechanical model. All models were coupled through a python wrapper to allow for appropriate data exchange. The neutronic model of the design was developed using MCNP and Serpent Monte Carlo codes, in order to calculate important parameters including criticality, control devices worth, power distribution, and temperature reactivity coefficients. The thermal conduction model of the solid-state core was developed and coupled to a heat pipe model using Ansys Fluent, to calculate the temperature distribution in the reactor, while Ansys Mechanical was employed to conduct structural mechanical analysis through performing calculations of the stress, strain, and total deformation of the core. Multi-physics simulations of the design were carried out to provide analysis of both steady-state normal operating conditions and transient scenarios, including accidents related to heat pipe and control drum failures. The obtained results were used to assess the safety aspects of the proposed design and provide valuable insights necessary for the development of heat pipe micro reactors in the near future
Influence of Dietary Saccharomyces cerevisiae Fermentation Product on Markers of Inflammation and Cartilage Metabolism in Young Exercising Horses Challenged with Intra-Articular Lipopolysaccharide
No full textThe objective was to evaluate dietary Saccharomyces cerevisiae fermentation product (SCFP) on joint inflammation and cartilage metabolism in exercising yearlings challenged with intra-articular lipopolysaccharide (LPS), hypothesizing SCFP (TruEquine��C, Diamond V Mills, Inc.) would ameliorate inflammation and increase cartilage metabolism. Thirty Quarter Horse yearlings were stratified by bodyweight (BW), age, sex, and assigned to (n =10/dietary treatment): control (0), 46, or 92 mg/kg BW/d SCFP. Treatments were top-dressed to 1% BW concentrate. Horses were stalled, offered ad libitum Coastal bermudagrass hay, and exercised for 30 min/d, 5 d/wk. Every 21 d, wither height (WH), hip height (HH), heart girth (HG), body length (BL), and BW were obtained. On d 46, horses underwent an LPS challenge with each radial carpal joint receiving 0.8 mL of a 0.5 ng LPS solution or sterile lactated Ringer���s solution (LRS). Synovial fluid was collected pre (h 0), and 6, 12, 24, and 336 h post-injection, and analyzed for prostaglandin E2 (PGE2), carboxypropeptide of type II collagen (CPII) and collagenase cleavage neopeptide (C2C) via ELISA, and chemokines (CCL2, and CCL11) and cytokines (TNF�� and IL-10) via multiplex platform. Rectal temperature (RT), heart rate (HR), respiration rate (RR), and carpal circumference (CC) were recorded prior to arthrocentesis. Data were analyzed using MIXED procedure of SAS. By d 56, growth parameters increased (P < 0.01) where control had a greater increase in BW than SCFP groups (P < 0.01). Clinical parameters were uninfluenced by diet (P ��� 0.29) but varied over time (P ��� 0.03). Treatments didn���t influence CPII, C2C, CPII:C2C (P ��� 0.46) or logPGE2, logCCL2, CCL11, and logIL-10 (P ��� 0.23). There was an interaction for CCL11 (P = 0.04) where control was greater than SCFP groups at h 6. Furthermore, logIL-10 had an interaction where 46 mg/kg was lower at h 12 compared to control and 92 mg/kg (P = 0.05). There was a treatment effect for TNF�� (P = 0.04) where 92 mg/kg was lower than 46 mg/kg and tended to be lower than control. Although SCFP didn���t influence cartilage metabolism or logPGE2, SCFP may ameliorate inflammatory cytokines and chemokines following an acute, intra-articular insult
Impact of Immune Reactions and Crosslinking Chemistry on Hydrogel Properties and Performance
No full textHydrogels are hydrophilic, three-dimensional structures that can be synthesized from synthetic and natural polymers for use in various tissue engineering applications. Their efficacy, however, is heavily dependent on the immune reaction to the material used. Another feature of hydrogels is their tunability in physicochemical properties, which can be modulated based on the crosslinking chemistries used to synthesize the structure. While often treated as being interchangeable, recent evidence suggests crosslinking chemistry���s potential to significantly impact material properties. Here, we sought to investigate the implications of polymer immunogenicity and crosslinking chemistry on hydrogel design and application.
Our first goal was to investigate poly(ethylene glycol) (PEG), a synthetic polymer considered to be bioinert, and how sensitization to the polymer impacts tissue engineering efficacy. To this end, PEG-based microporous annealed particle (MAP) hydrogels were assembled in situ of critical-sized calvarial defects through bioorthogonal tetrazine click reactions, and bone formation and morphology was found to be significantly influenced by PEG sensitization. Next, a head-to-head comparison of annealing chemistry used during MAP hydrogel assembly was further characterized between tetrazine-norbornene click reactions and radically-mediated thiol-norbornene click reactions. Differences in materials properties, such as storage moduli and susceptibility to enzymatic degradation, emerged as a result of annealing chemistry and were further modulated with respect to TNCP concentration. We deduced tetrazine-norbornene click products (TNCPs) induce secondary interactions that contribute to these changes, but these distinctions were negligible when applied in vivo.
Next, we evaluated whether the modulatory effects of TNCP-induced interactions could be applied in polymer-based biomaterials other than PEG. Specifically, we applied various concentrations of TNCPs to a hyaluronic acid (HA)-based bulk hydrogel and observed tetrazine-mediated changes to material properties. We also were able to leverage these interactions to assemble a supramolecular HA hydrogel that demonstrated shear-thinning and self-healing behavior that suggest potential as an injectable material, which was assessed in vitro using a genetically engineered strain of bacteria. Finally, TNCP-induced secondary interaction were leveraged in development of a hydrogel platform where a mock therapeutic was directly conjugated onto the HA backbone. Retention of the conjugated molecule and minimal degradation of the platform was observed after one week
A Massively Parallelizable Surrogate-Based Modeling Framework for Nonlinear Static Aeroelasticity and Structural Design
No full textAnalyzing the multiphysical coupling between a deformable structural body and the forces
imposed on that body from a surrounding fluid can be a challenging and computationally expensive
task, especially when the structure and/or fluid exhibit highly nonlinear behavior. Consequently,
preliminary design of aerostructures often relies upon simplified mathematical models
limited to linear fluid and structural regimes to enable tractable exploration within a design space
predominantly defined by convention and engineering expertise. While this has historically proven
reliable, such design practices are inadequate for developing next-generation aerial systems requiring novel structural solutions for in situ geometric reconfigurations that enable continuous
optimization of aerodynamic performance, enhanced control authority, and expansion of operational
capacity. Accordingly, there exists a need for novel reduced-order multidisciplinary analysis
techniques agnostic to the underlying complexities of the physical problem that make efficient
use of high-fidelity computational models to resolve the exchange of field information between
disparate physics subdomains. This work explores a highly parallelizable non-intrusive reduced-order
modeling technique that seeks to construct an aeroelastic surrogate model approximating the
function composition of the high-fidelity structural model and fluid model in terms of shape parameters characterizing a reduced geometric description of the deformed interface boundary between physics domains. The proposed methodology removes the need for a reduced-order representation of the traction field acting on the structure, eliminates computationally expensive fluid evaluations during structural design procedures, and requires no explicit communication between independent fluid and structural models. Furthermore, while this data-driven modeling approach is highly enabling for parametric multi-objective structural design optimization during preliminary design
stages, identifying structural design variables requires foreknowledge of the structural topology.
This work applies many of the same principles to develop a novel reduced-order aeroelastic topology
optimization framework that supplements conceptual design stages with knowledge of the static aeroelastic response while considering nonlinear aerodynamics
Border Commuting Student Experiences: Developing Transborder/Transfronterize Identities
No full textOscar Martinez argues that an international border is a ���line that separates one nation from another��� to keep the people in the poor country out of the rich country (1994:5). Border commuters cross international borders daily/weekly and participate in each country's society, straddling both physical and non-physical boundaries in the borderlands (Anzaldua 1987; Carter 2006). This thesis focuses on the identity development of high school border commuters, referred to as transfronterize/transborder students (Stephen 2007; Iglesias-Prieto 2011). In addition to the analysis of transborder complex identities and Prudence Carter���s (2006) concept of student ���boundary straddling,��� this study uses Falc��n Orta & Orta Falc��n���s (2018) Transborder Identity Formation Framework to examine how the experiences of border commuter high school students develop transfronterize/transborder identities. The guiding question in this study is: ���In what ways does border commuting for educational purposes shape the identity development of high school transborder/transfronterize students?��� Two specifying questions follow: ���How well do Falcon Orta and Orta Falcon���s Identity Formation Framework apply to transborder high school students?��� and ���How are the identity development experiences of high school transborder students similar/different to that of transborder college students based on the existing theory?��� To answer these questions, qualitative methods were used to explore transborder students��� self-perception, educational aspirations, and border commuting experiences. The findings indicate that the existing framework for transborder college students applies to the experiences of transborder high school students; however, younger students have influential factors that do not apply to college students and vice versa in developing their complex transborder identities