Modeling of joints for the dynamic analysis of truss structures

An experimentally-based method for determining the stiffness and damping of truss joints is described. The analytical models use springs and both viscous and friction dampers to simulate joint load-deflection behavior. A least-squares algorithm is developed to identify the stiffness and damping coefficients of the analytical joint models from test data. The effects of nonlinear joint stiffness such as joint dead band are also studied. Equations for predicting the sensitivity of beam deformations to changes in joint stiffness are derived and used to show the level of joint stiffness required for nearly rigid joint behavior. Finally, the global frequency sensitivity of a truss structure to random perturbations in joint stiffness is discussed

The Incidence of Staphylococcus aureus Mastitis in Maine Dairy Cattle

This project investigated the factors surrounding the incidence of Staphylococcus aureus (SA) mastitis in Maine dairy cattle. This type of mastitis is driven by an antibiotic resistant pathogen that is very contagious among cattle, though farmers are often unaware of how common this type of mastitis is and that it could be present in their herds. My hypothesis was that specific farm factors, like milkers performing other tasks during milking, as well as the act of pre-dipping versus not pre-dipping, would explain the increase in SA mastitis. A thirty-seven-question IRB-approved survey was subsequently distributed to farmers in the University of Maine Extension contact list and to farmer Facebook groups. Among a total of 11 responses, SA mastitis was seen in farms that do and do not pre-dip, in those whose milkers do not palpate the cow’s udder before unit removal, and in those where the cow is allowed to lie down shortly after being milked. In addition, seven of the survey respondents had a history of SA mastitis, and only two of them were able to eradicate it from their herds. Overall, the results showed that SA mastitis occurs on both small- and large-scale farms, and areas of management could be changed to decrease the presence of SA mastitis, like the frequent changing of gloves and the palpation of the udders before the milking unit is removed. This project suggested that SA mastitis is common in Maine, and farmers may be unaware of whether this pathogen is infecting their herds

The 15 meter hoop-column antenna dynamics: Test and analysis

A 15 meter model of the hoop-column antenna concept has been vibration tested for model characterization and analytical model verification. Linear finite element analysis predicted the global vibration frequencies accurately. Good agreement between analysis and test data was obtained only after the analytical model was refined using static test data. As structures become more flexible, structural properties determined from static data become more accurate and should be used to update analytical models. Global vibration modes are not significantly affected by the surface mesh which permits simplified analytical models to be used for prediction of global behavior. These reduced models are believed sufficient for preliminary design and controls simulations where only global behavior is desired. The mesh modes were highly damped due to the knit mesh used for the reflector surface. These modes were also highly coupled and very difficult to measure in the laboratory. The inability to fully characterize the antenna mesh modes in the laboratory indicates robust methods for active surface vibration suppression will be needed. Fortunately, the surface mesh exhibits high passive damping which should be beneficial to active control systems

Examining 3D Printed Antennas For Space Based Applications

3D printing is attractive for antenna manufacturing for a few reasons including the ability to make complex designs realizable that may have previously been too costly or unmanufacturable and the ability to build conformal designs. The idea of 3D printing antennas is not new and has been researched in recent years. However the possibility of using 3D printed antennas for space applications has been researched very little. The harsh space environment makes material selection an important factor in designing for space applications. Depending on location of the orbit of interest, there are several factors that must be considered when dealing with space including, high vacuum, magnetic fields, electromagnetic radiation (UV rays, X- ray, and gamma rays), charged electrons and protons, and extreme temperatures. In this project 3 patch antennas were 3D printed out of ABS for use at 5, 10, 25 GHz. The antennas underwent testing to understand how the 3D printed ABS material would react in a space conditions. The materials were exposed to radiation and vacuum environment in order to simulate space conditions

Exact methods for modal transient response analysis including feedback control

This paper presents a modal method for the analysis of controlled structural systems that retains the uncoupled nature of the classical transient response analysis of a structure subjected to a prescribed time-varying load. The control force is expanded as a Taylor series that remains on the right side of the equations, and it does not lead to a computational approach that requires coupling between modes on the left side. Retaining a sufficient number of terms in the series produces a solution to the modal equations that is accurate to machine precision. The approach is particularly attractive for large problems in which standard matrix exponential methods become computationally prohibitive. Numerical results are presented to show the accuracy and efficiency of the proposed approach for dynamic feedback compensation of a truss structure with local member modes in the controller bandwidth

An Intensive Cultural Resources Investigation for the Redbud Pump Station Transmission Water Line Project Collin County, Texas

The City of McKinney (City) is proposing to construct and maintain 2.2 kilometers (km; 1.4 miles [mi]) of 42- inch (in) water transmission line for the Redbud Pump Station Transmission Water Line Project (Project) located within the City of McKinney, in west-central Collin County, Texas (Appendix A, Figure 1). On behalf of the City, BGE, Inc. (BGE) conducted an intensive pedestrian survey augmented by shovel testing of the Project. Because the proposed project is being contracted by the City of McKinney, a political subdivision of the state of Texas, the project sponsor is required under the Texas Antiquities Code and the Texas Natural Resources Code Chapter 26 ‘Rules of Practice and Procedure for the Antiquities Code of Texas’ to obtain a Texas Antiquities Permit to perform cultural resources investigations to assess whether cultural resources are present that may rise to the level of significance of State Antiquities Landmark (SAL) status. The Texas Historical Commission (THC) has assigned Antiquities Permit number 8763 to the Project. Furthermore, project construction designs minimize impacts to Waters of the United States (WOTUS) crossed by the project, not meeting the minimum threshhold established under Section 404 of the Clean Water Act (CWA) for the requirement of a Pre-Construction Notification (PCN) to the United States Army Corps of Engineers (USACE)

HcpR of Porphyromonas gingivalis utilizes heme to bind NO

The obligate anaerobe Porphyromonas gingivalis is the etiological agent responsible for periodontal disease. It must withstand high levels of reactive nitrogen species in the oral cavity generated by the host and other oral flora. The mechanisms allowing for protection against such stress remain poorly understand. HcpR is an FNR-CRP family regulator that has been implicated in regulation of the nitrosative stress response. In this study we characterize the biochemical properties of HcpR. It is a homo-dimer that is composed of 3 domains – a heme-binding domain, dimerization helix, and a DNA-binding domain. Our studies show that HcpR binds the heme cofactor. UV-Vis and Raman spectroscopy reveal that the bound heme is capable of binding the diatomic gas molecule Nitric Oxide (NO)-a source of nitrosative stress. Binding of NO causes a change in the oxidation state of the iron. SAXS reveals the protein bears a structural resemblance to homology models generated from an ortholog. Promoterr studies reveal that mechanisms P. gingivalis-HcpR uses to modulate expression are novel and different than those found in E. coli and P. aeruginosa

Second Harmonic Generation Imaging of a Magnetic Topological Insulator

A topological insulator (TI) is a type of quantum material that is insulating in the bulk but metallic on the surface. Due to the unique spin properties of the surface electrons, TIs have attracted much interest for their potential applications in spin-based electronics and quantum computers. Even more exotic effects occur when TIs are brought in contact with magnetic materials. This thesis represents a study of two-layer thin films consisting of the TI Bi2Se3 and the magnetic insulator EuS using a nonlinear optical technique called second harmonic generation (SHG) imaging. SHG imaging can probe the crystal and magnetic structure at the surfaces and interfaces of inversion symmetric materials. At the interface between the EuS and Bi2Se3 layers, magnetic domains are expected to form. The domain boundaries are predicted to host chiral edge states, which are dissipationless currents that flow in one direction around a domain. Using SHG imaging, our goal was to visualize the magnetic domains in this magnetic topological insulator system. Even though we have yet to observe any evidence of magnetic domains in this material, we also performed SHG imaging on monolayer MoS2 and were able to visualize distinct crystal grains. Our SHG imaging setup that was improved upon during this thesis has the potential to reveal information about other interesting quantum materials

The Decline of Youth at Ministry Under The Sky

The decline of youth attending their services is no secret for many churches. The influences of the world, technology, wanting to fit in are just a few reasons youth find other things to do than attend their church services faithfully. Ministry Under The Sky is a small ministry with a big heart. At its birth in 2001, Ministry Under The Sky’s start was in the researcher’s home and her husband, the Overseer of the ministry. God blessed Ministry Under The Sky with its first building in 2007. The church outgrew the first two buildings less than two years each. The third location’s stay was three and a half years. The ministry was known in the community for being relational, helping others, and their energetic youth learning about the Lord and how to live for Him. However, as the youth began to age out, some went to college, the Army, and moved out-of-state, the youth’s attendance began to dwindle. The things the ministry was well known for to attract youth and families, inadvertently they got away from doing them. The lack of youth in their services actively engaging and their parents is an issue at Ministry Under The Sky. The Compassion Authentic Respect Educate Mentoring Empowerment mentoring ministry’s birth will help the ministry become relational once again, see current and new youth emerging actively at Ministry Under The Sky, and families evolve and grow spiritually once again