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INCREASING DRIFT CAPACITY OF NON-DUCTILE CONCRETE SHEAR WALLS THROUGH CONFINEMENT WITH FIBER-REINFORCED POLYMER APPLICATION
Get PDFThe seismic response and laboratory testing of pre-1980s reinforced concrete (RC) shear walls commonly exhibit undesirable concrete crushing and rebar buckling in the wall end-zones leading to a flexural compressive failure. The lack of ductility of these walls is attributed to low reinforcement ratios and absence of special boundary elements (SBE) as required by modern design code. Thus, the authors are proposing a fiber reinforced polymer (FRP) retrofit method to provide confinement to the end-zones of pre-1980s walls equivalent to that of an SBE. Current industry applications of FRP have largely been for shear strengthening of RC beams, columns, and slabs. In contrast, the large-scale experimental study described in this paper aims to determine the effectiveness of FRP sheets and splay anchors as confinement of pre-1980s wall end-zones to increase the compressive strain capacity, delaying both concrete crushing and rebar buckling that precipitate the flexural compression failure. This is anticipated to increase wall drift capacity and potentially change the failure mechanism to one that is more ductile. Results from this study would demonstrate the feasibility of this FRP wall retrofit method to industry practitioners, especially attractive due to the relatively low-cost nature and minimally invasive implementation. The Cal Poly research team previously conducted a pre-1980s wall test (Ostrom, 2018; de Sevilla & Luong, 2020) and modelling in PERFORM-3D (Doan & Williams, 2020). The wall specimen design discussed herein, Wall R2-FRP, was proportioned from walls tested by Lu et al. (2017) to achieve a flexural compression failure, with predictions per ASCE 41-23 and Priestley’s (2007) Lumped Plasticity model confirming this target response
Anchoring Athlete Safety: A Case Study of the Minor Athlete Abuse Prevention Policies of USA Gymnastics
Get PDFIn response to the unprecedented scrutiny following the Larry Nassar case, USA Gymnastics initiated comprehensive policy reforms aimed at strengthening the safeguarding framework for its minor athletes. The purpose of this study was to examine the organization\u27s current minor athlete abuse prevention policies and evaluate their effectiveness. A case study was conducted on USA Gymnastics through a tool created by the researcher with data collected from USA Gymnastics Safe Sport Policy, the US Center for Safe Sport, and USA Gymnastics governing structure. While USA Gymnastics has created a formidable policy to protect its minor athletes, significant gaps still remain. The Recommendations of this study focus on mandated education and increased representation for athletes, as well as measures to better ensure the integrity of the existing policies
Implications Of Persistent Micro-bioplastics On Biogeochemical Properties Across Soil Types
Get PDFTerrestrial microplastics are increasing in abundance and are an emerging contaminant of concern, particularly in agriculture ecosystems where plastic use and subsequent soil contamination are prevalent. Plastic film mulches make up a significant portion of the plasticulture industry and are directly linked to soil microplastic pollution where negative effects to soil biotic and abiotic functions have been observed. In response to this issue, biodegradable film mulches have been promoted as a sustainable alternative to conventional polyethylene-based mulches. These biodegradable mulches, composed of various bioplastics, are designed to be tilled back into the soil where they are expected to decompose. However, the degradation of biodegradable film mulches has proven to be inconsistent and unpredictable, potentially leading to the persistence of micro-bioplastic (MBP) particles in the soil that may cause adverse effects like those of microplastics from conventional mulches. To evaluate the efficacy of this novel technology as a viable alternative to conventional plastic mulches, this 2-month incubation study examined the effects of MBPs derived from polybutylene adipate terephthalate (PBAT)-based biodegradable mulch on a suite of soil health indicators. Using laboratory-prepared soils, the study assessed how clay mineralogy and organic matter content influence soil-MBP interactions under controlled conditions. Our results suggest there is a significant effect of MBPs on soil moisture and nutrient cycling with a potential negative priming effect, particularly in soils where organic matter is limited. Additionally, clay mineralogy significantly mediated soil-MBP interactions. While MBP presence altered C pools, a qualitative analysis suggests the MBP particles remained largely undegraded by the end of the incubation period. These findings suggest that MBPs have the potential to influence soil properties and functions, underscoring the need for further research to fully understand their environmental implications in field conditions
Design, Manufacturing, and Assembly of Modular Snake-Like Robotic Arm, Alongside Design and Implementation of System’s Digital-Twin
Get PDFA unique modular snake-like robotic arm, also referred to as MA\RS – the Modular Arm \ Robotic System - was designed, manufactured, assembled, simulated, and programmed to create a modular robot which could move to a desired end position given the number of links, the position of the end link and the duration of motion. This robotic arm serves as the start of research into a modular space robotic system to be used in low-gravity environments. As such, this project focused on developing the initial design of the robot and its digital twin. The system’s modularity allows for changes to the robot’s workspace, which allow for the accomplishment of different tasks. The modular aspect of the robot required strong and lightweight links and used a bent sheet metal assembly to reduce mass and conserve strength. Each of the robot’s links used a custom-built PCB to power the system, send signals from the MCU (an ESP32-S2) to the motor, and communicate to the main controller using CAN Bus. Simulation of the robot was performed using a MATLAB script and GUI built in MATLAB’s App Designer, which calculated the system’s path planning and inverse kinematics. The GUI communicated with the robot (through serial) and controlled the robot’s motion as it was calibrated and moved from one location to another
Effects of Feeding Essential Oils and Prebiotics on Late Laying Hen’s Egg Production, Quality, and Gut Microbiome
No full textThe increasing regulation of antimicrobial use in agriculture has driven the search for alternative solutions that support livestock health and production. Essential oils (EO) and prebiotics have recently gained attention as potential alternative supplements due to their antimicrobial properties (benefits for gut health) and ability to improve production parameters in livestock. This study evaluates the impact of a commercially available blend of EO and prebiotics on laying hen production parameters, egg quality, and Gastrointestinal microbiota composition as a possible substitute for antibiotic growth promotors (AGPs). Sixty Hy-Line W-80 laying hens, aged 60 weeks, were divided into four dietary treatment groups: 1) a corn-soybean meal-based basal diet (control), 2) the control diet mixed with 0.5 kg EO (low EO), 3) the control diet mixed with 1.0 kg EO (High EO), 4) the control diet supplemented with 0.5 kg prebiotics (prebiotic). Each diet was administered for 12 weeks, and phased feeding did not occur. Egg production and feed intake were measured weekly, egg quality was measured biweekly, bird body weight was measured monthly, and microbiome samples from both the ileum and ceca were collected at the conclusion of the feeding trial. Repeated measures ANOVA was used to analyze the data for egg production, egg quality, and feed intake using the GLIMMIX function in SAS (9.4). Microbiome samples were processed and analyzed differently. Briefly, 16s rDNA sequencing was conducted on the NovaSeq platform using paired-end reads. Microbiome data underwent quality control and chimera filtering using DADA2. Clean data was then used to construct operational taxonomic units (OTU), and proceed with diversity analysis, species classification annotation, and differential analysis. Taxonomic classification was performed using SILVA (release 138) and NT-16s databases with confidence level set at \u3e0.07. Differential abundance analysis was conducted based on the relative abundance table. Fisher\u27s exact test, Mann-Whitney U, and Kruskal-Wallis tests were used for statistical differences testing.
Results showed that prebiotic supplementation negatively affected both body weight (p0.05) on these metrics. Prebiotic-fed hens also exhibited reduced egg production (p = 0.002) compared to control and EO diets. Although egg weight, yolk color, yolk weight, and albumen height remained consistent across treatments (p\u3e0.05), external egg quality assessments revealed significant differences in eggshell thickness and breaking strength between the low and high EO diets (p = 0.01; p = 0.0003, respectively), though these treatments were not significantly different when compared to the control diet.
Microbial analysis showed higher microbial diversity in the ceca when compared to the ileum (p \u3c 0.001), with a highly dominant presence of the Lactobacillalesgenus in the ileum. Notably, high EO diets significantly increased Lactobacillus coryniformis (p = 0.009) and Lactobacillus capillatus (p = 0.04) compared to the control diet. Clostridium sensu stricto (mean 0.011) and Salmonella bongori (mean 0.001) were witnessed in control diet birds, while these microorganisms were absent from the high EO and prebiotic diet fed birds. Lastly, this feeding trial observed that the vast majority of potentially pathogenic, anaerobic, biofilm former, and gram-negative microorganisms are found in the ceca. In contrast, aerobic, facultative anaerobic, and mobile microorganisms are found in the ileum.
These findings suggest that while EO supplementation alone does not enhance production parameters or egg quality compared to standard diets, it could support beneficial microbiota, offering a promising route to reduce AGP reliance and mitigate antibiotic resistance in livestock production