Finite Element Modeling of Delamination Damage in Carbon Fiber Laminates Subject to Low-Velocity Impact and Comparison with Experimental Impact Tests Using Nondestructive Vibrothermography Evaluation

Carbon fiber reinforced composites are utilized in many design applications where high strength, low weight, and/or high stiffness are required. While composite materials can provide high strength and stiffness-to-weight ratios, they are also more complicated to analyze due to their inhomogeneous nature. One important failure mode of composite structures is delamination. This failure mode is common when composite laminates are subject to impact loading. Various finite element methods for analyzing delamination exist. In this research, a modeling strategy based on contact tiebreak definitions in LS-DYNA®was used. A finite element model of a low-velocity impact event was created to predict delamination in a composite laminate. The resulting delamination relative size and shape was found to partially agree with analytical and experimental results for similar impact events, while the force-time plot agreed well with experimental results. A small difference in contact time in the simulation compared to experimental testing is likely due to the omission of composite failure modes other than delamination. Experimental impact testing and subsequent vibrothermography analysis showed delamination damage in locations shown in previous research. This confirmed the validity of vibrothermography as a nondestructive evaluation technique for analyzing post-impact delamination

Cable Drag Test

The Smooth Shifters is a team composed of Alex Powers, Brandon Roy Sadiarin, George Rodriguez, and Torey Kruisheer. We are four senior mechanical engineering students at California Polytechnic State University (Cal Poly) in San Luis Obispo, California that are working on a senior design project for Specialized Bicycle Components, Inc. located in Morgan Hill, California. We will be under the advisement of Professor Sarah T. Harding of the mechanical engineering department at Cal Poly. Specialized, one of today’s leading bicycle companies, is in need of a test setup that measures brake and shifter cable drag. High performance cyclists using time trial, triathlon, and aero bikes are constantly looking for ways to have as much aerodynamic advantage as possible, paired with a low profile look on their bicycles. To address these issues, bicycle companies have started a new trend of routing cables inside of the bicycle frames, rather than running them outside the frames. Unfortunately, routing a cable through a bicycle’s frame causes additional cable drag which ultimately decreases shifting and braking performance. Specialized has requested a test setup that can be used to determine cable drag in any cable configuration prior to the fabrication of a physical prototype. The goals of this project are: To create a physical system to accurately mimic cable routing of a Specialized Tarmac bicycle frame and a comparative tool to measure the cable drag in competing systems. To create a simulation environment which allows a user to build a cable system to check performance without a physical test apparatus. A database of different routing systems and components can then be built up over time for continuous use with different frames

Acute Resistance Exercise Influences Bioelectrical Impedance Analysis Segmental Fat Mass Estimates

Bioelectrical impedance analysis (BIA) is an attractive tool for routine assessment of human body composition. However, there is also concern regarding how some variables, particularly exercise, may affect its measurements and therefore limit the conditions under which this technology can provide useful body composition data. PURPOSE: The purpose of this study was to determine if acute, localized resistance exercise (RE) compromises the validity of BIA segmental fat mass (FM) estimates. METHODS: In a crossover design, 32 healthy, resistance trained adults (18 F, 14 M; age: 23.4 ± 2.3 y; height: 172.4 ± 8.7 cm; body mass: 74.9 ± 15.3 kg; body fat: 25.6 ± 8.4%) completed three conditions in a randomized order: lower-body resistance exercise (L), upper-body resistance exercise (U), and rest (R). The RE protocol included a warm-up consisting of 2 sets of 12-15 repetitions of 3 upper-body exercises (U), or 3 lower-body exercises (L), followed by 5 sets of 10 repetitions per exercise, with 1-minute rest intervals. The R condition involved no exercise. BIA (InBody 770) was completed immediately pre- and post-exercise and at 15-, 30-, and 60-minutes post-exercise. The effects of the acute RE session on BIA estimates of total and segmental FM were analyzed using linear mixed-effects models with condition and time specified as within-subject factors and a random intercept for participant. In all models, the reference groups were R for condition and the pre-exercise time point for time. RESULTS: Condition by time interactions were observed for total and segmental FM. Examination of model coefficients indicated that most condition by time interactions were attributable to differences in the U condition across time relative to the reference group (i.e., R condition at baseline). In relation to the reference group, mean decreases of 0.75 to 1.25 kg for total FM, 0.38 to 0.58 kg for trunk FM, 0.27 to 0.47 kg for leg FM, and 0.15 to 0.22 kg for arm FM were observed in the U condition (p≤0.001 for all). In contrast, no changes across time were observed in the L condition. CONCLUSION: These findings suggest that an acute bout of localized RE influences BIA total and segmental FM estimates to an extent that can compromise accurate interpretation of the results. These data corroborate the need for a period of rest from physical activity, particularly upper body RE, prior to BIA body composition assessment

Strengthening Ukraine: Policy Recommendations for the New Administration

This project comprises four sections exploring how to strengthen Ukrainian institutions, the Ukrainian military, the Ukrainian economy, and how to assist the Ukrainians in countering Russian propaganda. Within each section we will present background on the topic and make recommendations for how the United States government can work with Ukraine

Patterns of Spiny Lobster (Panulirus argus) Postlarval Recruitment in the Carribbean: A CRTR Project

As part of the Coral Reef Targeted Research (CRTR) Program, a partnership between the Global Environment Facility and the World Bank, our research team examined the recruitment patterns of Caribbean spiny lobster (Panulirus argus) postlarvae among regions in the Caribbean, with a particular focus on Mesoamerica. Our goal was to collect comparable information on postlarval supply among regions and to provide data to test predictions of connectivity generated from a coupled biophysical oceanographic model of lobster larval dispersal. Here we present the results of the postlarval recruitment monitoring program. We monitored the catch of postlarvae on Witham-style collectors at sites in the Caribbean from March 2006 to May 2009, although the duration and frequency of sampling varied among locations. Recruitment varied considerably among months and locations. It peaked in the Western Caribbean in the fall (Oct - Dec), whereas in Florida, Puerto Rico, and Venezuela peaks were in spring (Feb - April) with a smaller peak in the fall. Sites generally fell into two groups with respect to monthly variability in recruitment: low variability sites (e.g., Honduras, southern Mexico, Venezuela) and high variability sites (e.g., Florida, San Andres Islands, Puerto Rico, northern Mexico). Recruitment magnitude varied locally, but generally increased (lowest to highest) from Puerto Rico, San Andres Islands, Honduras, Mexico, Venezuela, to Florida. Recruitment trends mirrored fishery catch in some locations, implying a recruit-to-stock linkage. Recruitment was significantly correlated among several sites, suggesting similarity in their larval sources and oceanographic regimes

Advanced Technologies for Oral Controlled Release: Cyclodextrins for oral controlled release

Cyclodextrins (CDs) are used in oral pharmaceutical formulations, by means of inclusion complexes formation, with the following advantages for the drugs: (1) solubility, dissolution rate, stability and bioavailability enhancement; (2) to modify the drug release site and/or time profile; and (3) to reduce or prevent gastrointestinal side effects and unpleasant smell or taste, to prevent drug-drug or drug-additive interactions, or even to convert oil and liquid drugs into microcrystalline or amorphous powders. A more recent trend focuses on the use of CDs as nanocarriers, a strategy that aims to design versatile delivery systems that can encapsulate drugs with better physicochemical properties for oral delivery. Thus, the aim of this work was to review the applications of the CDs and their hydrophilic derivatives on the solubility enhancement of poorly water soluble drugs in order to increase their dissolution rate and get immediate release, as well as their ability to control (to prolong or to delay) the release of drugs from solid dosage forms, either as complexes with the hydrophilic (e.g. as osmotic pumps) and/ or hydrophobic CDs. New controlled delivery systems based on nanotechonology carriers (nanoparticles and conjugates) have also been reviewed

Detection of Gamma-Ray Emission from the Starburst Galaxies M82 and NGC 253 with the Large Area Telescope on Fermi

We report the detection of high-energy gamma-ray emission from two starburst galaxies using data obtained with the Large Area Telescope on board the Fermi Gamma-ray Space Telescope. Steady point-like emission above 200 MeV has been detected at significance levels of 6.8 sigma and 4.8 sigma respectively, from sources positionally coincident with locations of the starburst galaxies M82 and NGC 253. The total fluxes of the sources are consistent with gamma-ray emission originating from the interaction of cosmic rays with local interstellar gas and radiation fields and constitute evidence for a link between massive star formation and gamma-ray emission in star-forming galaxies.Comment: Submitted to ApJ Letter