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Optimal Concrete Mix Design and Finish for Skateboarding Performance
Get PDFWhile concrete has been used in construction for hundreds of years, the introduction of concrete to skateboarding is a relatively new development. Concrete and concrete finishes are very well studied in the context of buildings and building design. Shotcrete is also very well understood as it has been in use for over 100 years. Because it is a relatively new sector of the industry, concrete skatepark construction is an area that has plenty of room for research and development. This research paper will describe the finish methods and mix designs used for concrete skatepark construction by leading skatepark construction companies and professionals. Professionals from both the project management side and the field side will be interviewed. The interviewees also identify some other factors that affect concrete skatepark surfaces. This paper will also describe the results of data gathered in the field from surveys at two skateparks. This data will compare the theories of concrete skatepark construction methods with the results of the finished product and its performance as viewed by the actual users. Overall this research aims to discover the optimal mix design and finish methods for concrete skateparks based on skateboarding performance on the concrete surface
Assessing the Effectiveness of Noise Ordinances on Residential Construction: A Case Study in San Luis Obispo
Get PDFConstruction activities inherently generate substantial noise. As a result, construction becomes a notable source of ambient sound that permeates populated areas daily. This sound, especially at extreme volumes, can be the source of significant public annoyance and anger. Studies have shown that prolonged noise exposure can lead to hypertension, distraction, and even cognitive impairment in children. For these reasons, local governments will set noise ordinances to limit when and at what volume construction sounds can be made. The purpose of this study was to determine the effectiveness of these noise ordinances set by the city of San Luis Obispo. The effectiveness was gauged by the level of satisfaction of residents neighboring four distinct job sites. Interviews were conducted with neighbors and contractors. Additionally, decibel readings were taken at the jobs to determine contractor compliance with volume limits. All four jobs had readings well below the city limit of 75 dBA. Every neighbor that was interviewed had either a neutral or positive impression of the sound emitted from sites. Lastly, all four contractors were void of noise complaints. It can be reasonably concluded that the noise ordinances effecting residential construction in the city of San Luis Obispo are working as intended
Associations Between Technology Use, Responsive Feeding, and Child Temperament Among Prior Prenatal Intervention Participants
Get PDFObjectives: The primary objective was to examine associations between mothers’ television and mobile device (TV/MD) use and responsive feeding during an observed mother-toddler mealtime interaction. The secondary objective was to assess whether dimensions of child temperament were associated with mothers’ TV/MD use. Methods: Participants from a prenatal lifestyle intervention trial to prevent excess gestational weight gain among women with overweight and obesity (N 5 77) were observed during a dinnertime meal when their children were aged 19.4 6 0.9 months. Trained video coders used the Responsiveness to Child Feeding Cues Scale to rate child strength of early/subtle, positive active, and negative active satiation cues and maternal responsiveness to these cues. Coders also recorded mothers’ use of TV/MD. Child temperament was reported by mothers through the Infant Behavior Questionnaire–Revised Very Short Form. Results: Twelve percent (n 5 9) of mothers used TV/MD during the mealtime interaction. Children whose mothers used TV/MD exhibited stronger early/subtle cues (4.1 6 0.4) compared with children whose mothers did not use TV/MD (3.4 6 0.2; p 5 0.04). Mothers who used TV/MD exhibited significantly lower responsiveness to child satiation cues (2.0 6 0.4) than those who did not use TV/MD (3.4 6 0.2; p 5 0.001). Greater child temperamental negative affectivity was associated with a greater likelihood of maternal TV/MD use (OR 5 4.80, 95% CI 5 1.21, 19.03). Conclusion: Mothers’ TV/MD use was associated with greater child temperamental negative affectivity and lower responsiveness to child cues
Robotic Origami Worm
Get PDFSoft robotics can solve many unique engineering problems. The ancient art of origami has inspired design for a new breed of robots. In this research, a novel fold design was created which has high linear stiffness, high bending stiffness, and the ability to deform omnidirectionally in order to turn. The robot is operated using a DC motor to expand and contract and electromagnets to control friction. The robot moves very quickly compared with many other origami robots in the literature. Other interesting ways to control friction were explored including expansion mechanisms. An origami design was created and tested that expands radially as it is contracted its longitudinal axis. Future work will design will combine these structures to create a robot that can move through pipes
Exploring and Operationalizing Inclusive Teaching in Engineering Education
Get PDFInclusive teaching is vital in engineering education because of its potential to enhance learning for all students. The purpose of this research is to explore faculty experiences with inclusive teaching, specifically focused on engineering settings. Our findings highlight dominant beliefs, practices, and challenges that emerged from our preliminary analysis. Future work will corroborate these findings with additional faculty as well as engineering student perspectives and beliefs
Efficiency Study of a Hybrid AC/DC House
Get PDFWith the proliferation of residential-scale renewable energy sources and DC loads, it has become attractive to use residential DC electrical system that could offer benefits over the legacy residential AC electrical system. The Hybrid AC/DC house provides a sustainable alternative to preexisting residential electrical system by having both AC and DC buses. The DC bus facilitates the connection from DC sources to DC loads, whereas the AC bus interfaces AC sources to AC loads. The study develops the equations to calculate losses based on a model consisting of four main components: Multiple-Input Single-Output (MISO) converter, AC-DC converter, inverter, and DC-DC converter. Parameters such as AC and DC bus voltages, load consumption, and number of AC and DC branches were used to construct multiple scenarios and evaluate efficiency. Results of the study show that the Hybrid AC/DC house displays higher efficiencies than when the house has AC only sources with higher DC load consumption. Similarly, the Hybrid AC/DC house has better efficiency than when the house has DC only sources under higher AC load consumption. For the DC bus, results of the study further indicate that the higher DC voltage level yields better efficiency than those obtained from lower DC voltages
Hydric Physiology of Lizards
Get PDFChapter 1: Animals can respond to extreme climate by behaviorally avoiding it, or by physiologically coping with it. We understand behavioral thermoregulation and physiological thermal tolerances, but water balance has largely been neglected. Climate change includes both global warming and changes in precipitation regimes, so improving our understanding of organismal water balance is increasingly urgent. We assessed the hydric physiology of endangered Blunt-nosed Leopard Lizards (Gambelia sila) by measuring cutaneous evaporative water loss (CEWL), plasma osmolality, body mass, and body condition throughout their active season. On average, G. sila had low CEWL that is likely desert-adaptive, and high plasma osmolality that is indicative of dehydration. Given that our study was in a drought year, it is reasonable to believe that every lizard measured was dehydrated to a degree. We hypothesized that throughout the G. sila active season, as their habitat got hotter and drier, G. sila would become increasingly dehydrated and watertight. Instead, CEWL and plasma osmolality showed minimal change for females and nonlinear change for males, which we hypothesize is connected to sex-specific reproductive behaviors and changes in food availability. We also measured thermoregulation and microhabitat use, expecting that more hydrated lizards would have higher body temperature, better thermoregulatory accuracy, and spend more time aboveground. However, we found no effect of CEWL, plasma osmolality, body mass, or body condition on these thermal and behavioral metrics. We posit either that G. sila tolerate dehydration to maintain activity during their brief active season, or that because every lizard was dehydrated due to the drought, they all experienced equally constrained thermoregulation and microhabitat use. Finally, G. sila spend considerable time underground in burrows, and we believe burrows serve as essential hydric, not only thermal, refugia. Our findings suggest that these lizards might benefit from artificial humid refugia and supplemental hydration, especially during drought.
Chapter 2: Testing acclimation plasticity informs our understanding of functional biodiversity and applies to conservation management amidst our rapidly changing climate. While there is a wealth of research on the plasticity of thermal and hydric physiology in response to temperature acclimation, there is a comparative gap for research on acclimation to different hydric regimes, as well as the interaction between water and temperature. We sought to fill this gap by acclimating Western Fence Lizards (Sceloporus occidentalis) to experimental climate conditions (crossed design of Hot or Cool, Dry or Humid) for eight days, and measuring cutaneous evaporative water loss (CEWL), plasma osmolality, hematocrit, and body condition before and after acclimation under common conditions. CEWL changed plastically in response to the different climates, with lizards acclimated to Hot Humid conditions experiencing the greatest increase in CEWL. Change in CEWL among individuals was negatively related to treatment vapor pressure deficit. Plasma osmolality, hematocrit, and body condition all showed greater changes in response to temperature than to humidity or vapor pressure deficit. CEWL and plasma osmolality were positively related across treatment groups before acclimation and within treatment groups after acclimation, but the two variables showed different responses to acclimation, suggesting that they are interrelated but governed by different mechanisms. This study is among just a small number of studies that assess more than one metric of hydric physiology and that test the interactive effects of temperature and humidity. Such measurements will be essential for predictive models of activity and survival for animals under climate change