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Influence of heat treatment and shielding gas environment on the very high cycle fatigue behavior of 17-4 precipitation hardened stainless steel
Get PDFAdditive manufacturing (AM) for stainless steel components has proved useful in a variety of industries ranging from aerospace to biomedical engineering. Many of these components are subject to very high cycle fatigue (VHCF) loading and must have tailored mechanical properties to ensure failures do not occur before a service life is reached. Testing the fatigue strength AM materials exposed to VHCF loading is paramount to compare with the expected life cycles of their wrought counterparts. In this thesis, AM 17-4 precipitation hardened (PH) stainless steel (SS) were fabricated using laser powder bed fusion (L-PBF) technique, while the wrought 17-4 PH SS specimens were manufactured using conventional methods. AM fatigue specimens were subjected to one of three heat treatments, including non-heat treated (NHT), CA-H900, and CA-H1025 to modify the microstructure and mechanical properties of the material. The influence of using either argon (Ar) or nitrogen (N2) as the shielding gas during L-PBF for AM specimens was also investigated. Wrought specimens were either left in the annealed state or given either an H900 or H1025 heat treatment.
The ultrasonic fatigue system used in this study applied uniaxial, fully reversed force-controlled force tests at 20 kHz to hourglass shaped specimens. Following ultrasonic testing, specimen fracture surfaces were inspected using a scanning electron microscope (SEM). Results revealed each post processing treatment method had an influence on the material’s fatigue life, crack initiation, and crack propagation characteristics. AM specimens showed a significant increase in fatigue life from heat treating to the CA-H900 condition when compared with those subjected to the NHT or CA-H1025 heat treatments. Using N2 as the shielding gas for the L-PBF process revealed a reduction in defect population and δ-ferrite when related to specimens fabricated using Ar as the shielding gas. Wrought specimens displayed improvement in fatigue life from H1025 heat treatment and consistently failed from inclusions, while their annealed counterparts consistently failed from pores. Experimental results revealed that post processing techniques for 17-4 PH SS must be carefully selected based on the mechanical loading the material will be exposed to over its service life
Assessing unoccupied aircraft and ground-based methods for detecting differences in intertidal oyster (Crassostrea virginica) reef structure
Get PDFEastern oyster (Crassostrea virginica) reefs provide critical ecosystem services, including shoreline stabilization, water filtration, and habitat for diverse marine species. However, these reef habitats are declining globally due to overharvesting, disease, and environmental change. This study evaluated the effectiveness of in-situ vs drone-based methods for detecting differences in oyster reef structure focusing on percent live cover and rugosity as key indicators. We also compared these methods in terms of cost, effort, and variability. Using data collected from Northeast Florida on a variety of reef types exposed to various disturbances, we developed generalized linear models to evaluate for differences among five reefs and compared the precision and scalability of both methods. Results demonstrate that drone-based approaches detected differences in percent cover and rugosity among reefs that were expected to vary, while in-situ methods did not. We found drone-based methods to have a similar cost to in-situ based methods in long-term studies, require less personnel, and cover copious amounts of area while providing meaningful metrics. This research advances our understanding of long-term oyster reef monitoring techniques and highlights the necessity for new technology-driven conservation strategies to improve management and restoration outcomes. We conclude with recommendations for incorporating drone technology into comprehensive long-term monitoring programs, highlighting its potential as a minimally invasive, scalable solution for marine ecosystem monitoring
Learning Outcomes–Rethinking Them for an AI World
Get PDFThis faculty workshop will explore how traditional learning outcomes must evolve in response to advancements in technology. The Office of Faculty Excellence and Academic Engagement will discuss the new competencies that become essential as AI is now capable of instantly generating content and solving complex problems. Additionally, participants will examine how to design educational frameworks that foster distinctly human capacities such as creativity, critical thinking, and ethical reasoning.https://digitalcommons.unf.edu/ofe_multimedia/1005/thumbnail.jp
Letter from R. Fortson to Eartha White
Get PDFCorrespondence: Handwritten letter from R. Fortson, a classmate of Eartha White. Includes note from unknown. Undated
Contribution Card, Florida\u27s Welcome to Hon. Frederick Douglass
Get PDFCard: Blank contribution card for Florida\u27s Welcome to Honorable Frederick Douglass. Card certifies the holder contributed 25 cents towards the Douglass Reception to be held on April 4, 1889. Signed by J.H. Sherman, Chairman of Ways and Means Committee. (Gift of Dr. Daniel Schafer). Undated
Newsclippng, Clara White Mission Ready For Annual Outing, July 16
Get PDFNews Clipping: Article regarding the annual outing of the Clara White Mission to be held at Moncrief Springs, Jacksonville, Florida. Undated
Instruction Request, Episode 6, Introducing Library VR Champion
Get PDFIn this episode of Instructions Request, (Recorded on Halloween 2024), Beryl White-Bing the Virtual Learning Librarian and Lauren Odom, the Instruction Librarian discuss Librarian Open Office hours and Pop Up Library Instruction, which are ways students can get on the spot help from a one of the Instruction Librarians.
Lauren Odom goes over the Research Question of the Day and warns about checking AI resources for article titles and resources and making sure there are no “Hallucinations.” Also, talked about is the new Primo Research Assistant and how to use it.
What’s happening in the VLC? Team building. One VR experience that Beryl talks about is Keep Talking and Nobody Explodes, which can has one person in VR and the others outside of VR with a Bomb defusal manual.
Beryl introduces a new segment called, Library VR Champion. The very first Library VR Champion is Dr. Kevin Pfeil, assistant professor of computer science. Dr. Pfeil discusses his role in VR with research and instruction and the importance of the VLC at the University of North Florida.
Important links in this episode
How to get help form a Librarian https://libguides.unf.edu/c.php?g=1369681&p=10120989
Research Assistant (Beta) in OneSearch - https://unf-flvc.primo.exlibrisgroup
Artificial Intelligence Library guide https://libguides.unf.edu/AI
Library VR Champion -Dr. Kevin Pfeil https://webapps.unf.edu/faculty/bio/N01539231
Keep Talking and No Body Explodes https://store.steampowered.com/app/341800/Keep_Talking_and_Nobody_Explodes/
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• University of North Florida\u27s Library home page - https://www.unf.edu/library/
• The Virtual Learning Center - https://libguides.unf.edu/VLC
• Recorded and edited by Andy Rush at the UNF Center for Instructional Research and Technology. https://www.unf.edu/cirt/creative-Vid...
• The Instruction Request Image: Chatgpt. (2024). Chatgpt (Plus). https://openai.com/chatgpt/
• The Instruction Request theme song: Udio. (2024). Udio. https://www.udio.com/https://digitalcommons.unf.edu/instructionpodcast/1005/thumbnail.jp
UNF VS Embry-Riddle [Neg# 26A]
No full textRoll of B+W Film scanned, UNF VS Embry-Riddle, Undatedhttps://digitalcommons.unf.edu/spinnaker-images/1168/thumbnail.jp
UNF VS Embry-Riddle_Roll2 [Neg # 2]
No full textRoll of B+W Film scanned, UNF VS Embry-Riddle, Roll 2, Undatedhttps://digitalcommons.unf.edu/spinnaker-images/1179/thumbnail.jp
UNF VS Embry-Riddle_Roll2 [Neg # 21]
No full textRoll of B+W Film scanned, UNF VS Embry-Riddle, Roll 2, Undatedhttps://digitalcommons.unf.edu/spinnaker-images/1198/thumbnail.jp