Development and implementation of star tracker based attitude determination

As interest in nanosatellites grows within the university community, the demand for inexpensive, space-grade hardware grows as well. Star trackers can be a luxury item for some spacecraft and therefore are often not considered due to their cost. Ideally, a star tracker could be built using inexpensive parts so long as the software is available. Unlike many other attitude determination instruments, star trackers are renowned for their high accuracy, yielding accurate and precise attitude estimates. However, development of this software can be overwhelming for the university settling, especially when multiple missions are on hand. If these instruments were readily available for more spacecraft, university-sponsored missions could expand to higher orbits and possibly deep space applications. Keeping in mind the cost and time constraints most university missions run into, the difficulty of developing an inexpensive star tracker stems from the integrated software. Hardware can be commercial off-the-shelf products, but the software is the more expensive of the two, and it is this software that is often lacking at the university level. With this, the proposed algorithm shows promise for the development, implementation, and testing of free star tracker software. The presented algorithm allows for a variety of interchangeable hardware, making it ideal for the academic community --Abstract, page iii

Enhanced Dynamometer for Conducting Long-Term Brake Wear Testing

The purpose of this project is to develop an automated control system for two constant torque dynamometers Krauss Friction Tester Type RWS60A – Serial no. 080 built in Orangeburg, West Germany recently obtained by FDP Friction Science. This control system will be efficient, effective, safer, and meet the standards of modern day technologies. Currently, the machines are outdated, obsolete, and unable to operate. Therefore, to bring the dynamometers back into full operation and be competitive in today’s industry a new control system that meets industry expectations must be implemented. For this reason, a programmable logic controller from Automationdirect named ClickPLC is being utilized. This industrial computer control system will continuously monitor the state of input for the device while determining the desired outputs based on a ladder logic program written by the control system designers. To create interference between the operator and the machine a C-more touch panel human machine interference from Automationdirect will be use. The HMI will provide a graphical interface designed to interchange and display graphics, animation and data from the PLC by touching the screen. The HMI will be programed accordingly to replace pushbuttons, switches, meters and any other analog input devices. This will streamline the brake life testing process down to a one-man operation for cost effectiveness.https://scholarscompass.vcu.edu/capstone/1196/thumbnail.jp

Forum 1: Social Inequality, Justice, and Vaccine Intent and Distribution in the United States

The key issues for the distribution of the COVID vaccine are shared. These issues include funding, racial and ethnic disparities, supply and logistics, communication and trust, federal, state and local roles, and coverage and costs

The Management and Dissemination of Electronic Navigational Chart Data in the 1990s

The capabilities of Electronic Charts are advancing rapidly and the growth of this new exciting technology will probably accelerate when GPS becomes available within the next few years. A considerable amount of work has been done in developing preliminary specifications and standards for the Electronic Chart and it is clear that accurate, up-to-date, Hydrographic Office chart data will be a key element to the success of these systems in the future. In anticipation of a growing demand for chart data, hydrographic and other agencies would be well advised to devote some attention to the creation of the necessary Electronic Navigational Chart Data Bases and data transfer mechanisms to manage and distribute the Electronic Navigational Chart data and updates. This paper describes some of the work that has been done in these areas recently. An information flow model that was developed by the International Hydrographic Organization Electronic Chart Updating Working Group is presented and the new terms that were needed are defined. Trends in Electronic Chart and related developments are also analyzed to determine what the Electronic Chart might be like in the mid 1990s. The problems of managing and disseminating the Electronic Chart data are also discussed

Mode-Cleaning and Injection Optics of the Gravitational-Wave Detector GEO600

The British–German interferometric gravitational-wave detector GEO600 uses two high-finesse triangular ring cavities of 8 m optical pathlength each, as an optical mode-cleaning system. The modecleaner system is housed in an ultrahigh-vacuum environment to avoid contamination of the optics and to minimize both the influence of refractive index variations of the air and acoustic coupling to the optics. To isolate the cavities from seismic noise, all optical components are suspended as double pendulums. These pendulums are damped at their resonance frequencies at the upper pendulum stage with magnet-coil actuators. A suspended reaction mass supports three coils matching magnets bonded onto the surface of one mirror of each cavity, allowing length control of the modecleaner cavities to maintain resonance with the laser light. A fully automated control system stabilizes the frequency of the slave laser to that of the master laser, the frequency of the master laser to the length of the first modecleaner and the length of the first to the length of the second modecleaner. The control system uses the Pound–Drever–Hall sideband technique and operates autonomously over long time periods with only infrequent human interaction. The duty cycle of the system was measured to be 99.7% during an 18 day period. The throughput of the whole modecleaner system is about 50%. In this article, we give an overview of the mechanical and optical setup and the achieved performance of the double modecleaner system

Infrared colours and inferred masses of metal-poor giant stars in the Keplerfield

Intrinsically luminous giant stars in the Milky Way are the only potential volume-complete tracers of the distant disk, bulge, and halo. The chemical abundances of metal-poor giants also reflect the compositions of the earliest star-forming regions, providing the initial conditions for the chemical evolution of the Galaxy. However, the intrinsic rarity of metal-poor giants combined with the difficulty of efficiently identifying them with broad-band optical photometry has made it difficult to exploit them for studies of the Milky Way. One long-standing problem is that photometric selections for giant and/or metal-poor stars frequently include a large fraction of metal-rich dwarf contaminants. We re-derive a giant star photometric selection using existing public g-band and narrow-band DDO51photometry obtained in the Keplerfield. Our selection is simple and yields a contamination rate of main-sequence stars of ≲1% and a completeness of about 80 % for giant stars with Teff ≲ 5250 K - subject to the selection function of the spectroscopic surveys used to estimate these rates, and the magnitude range considered (11 ≲ g ≲ 15). While the DDO51filter is known to be sensitive to stellar surface gravity, we further show that the mid-infrared colours of DDO51-selected giants are strongly correlated with spectroscopic metallicity. This extends the infrared metal-poor selection developed by Schlaufman & Casey, demonstrating that the principal contaminants in their selection can be efficiently removed by the photometric separation of dwarfs and giants. This implies that any similarly efficient dwarf/giant discriminant (e.g., Gaiaparallaxes) can be used in conjunction with WISEcolours to select samples of giant stars with high completeness and low contamination. We employ our photometric selection to identify three metal-poor giant candidates in the Keplerfield with global asteroseismic parameters and find that masses inferred for these three stars using standard asteroseismic scaling relations are systematically over-estimated by 20-175%. Taken at face value, this small sample size implies that standard asteroseismic scaling relations over-predict stellar masses for metal-poor giant stars

Student Involvement in Flipped Classroom Course Design

The purpose of this mixed-methods study was to examine changes in content knowledge, clinical reasoning, and metacognition with occupational therapy students involved in course design (collaborative participants), with participants engaged in flipped classroom model only (course participants), and to compare results between the collaborative and course participants. Forty-three occupational therapy students participated in this study. Researchers administered three pre- and post-test questionnaires and completed three focus groups. Results demonstrated both groups experienced growth in active learning and clinical reasoning and changed their perception of student involvement. The collaborative participants demonstrated additional benefits of development of relationships, increased accountability, and improved metacognitive learning

Exploring Cold War Religious Persecution Using the Rank-Order Approach

This lesson explores religious persecution in East Germany. Students must decide plausible actions to take against the Protestant Church to diminish power. Acting as a member of The East German Secret Police, students, evaluate, rank, and justify decisions to minimalize Christianity in an atheist society

Exercise prescription improves exercise tolerance in young children with CHD:a randomised clinical trial

Objective The main objective of this study was to ascertain if a structured intervention programme can improve the biophysical health of young children with congenital heart disease (CHD). The primary end point was an increase in measureable physical activity levels following the intervention.Methods Patients aged 5–10 years with CHD were identified and invited to participate. Participants completed a baseline biophysical assessment, including a formal exercise stress test and daily activity monitoring using an accelerometer. Following randomisation, the intervention group attended a 1 day education session and received an individual written exercise plan to be continued over the 4-month intervention period. The control group continued with their usual level of care. After 4 months, all participants were reassessed in the same manner as at baseline.Results One hundred and sixty-three participants (mean age 8.4 years) were recruited, 100 of whom were male (61.3%). At baseline, the majority of the children were active with good exercise tolerance. The cyanotic palliated subgroup participants, however, were found to have lower levels of daily activity and significantly limited peak exercise performance compared with the other subgroups. One hundred and fifty-two participants (93.2%) attended for reassessment. Following the intervention, there was a significant improvement in peak exercise capacity in the intervention group. There was also a trend towards increased daily activity levels.Conclusion Overall physical activity levels are well preserved in the majority of young children with CHD. A structured intervention programme significantly increased peak exercise capacity and improved attitudes towards positive lifestyle changes

Pan-Antarctic analysis aggregating spatial estimates of Adélie penguin abundance reveals robust dynamics despite stochastic noise

© The Author(s), 2017. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Nature Communications 8 (2017): 832, doi:10.1038/s41467-017-00890-0.Colonially-breeding seabirds have long served as indicator species for the health of the oceans on which they depend. Abundance and breeding data are repeatedly collected at fixed study sites in the hopes that changes in abundance and productivity may be useful for adaptive management of marine resources, but their suitability for this purpose is often unknown. To address this, we fit a Bayesian population dynamics model that includes process and observation error to all known Adélie penguin abundance data (1982–2015) in the Antarctic, covering >95% of their population globally. We find that process error exceeds observation error in this system, and that continent-wide “year effects” strongly influence population growth rates. Our findings have important implications for the use of Adélie penguins in Southern Ocean feedback management, and suggest that aggregating abundance across space provides the fastest reliable signal of true population change for species whose dynamics are driven by stochastic processes.H.J.L., C.C.-C., G.H., C.Y., and K.T.S. gratefully acknowledge funding provided by US National Aeronautics and Space Administration Award No. NNX14AC32G and U.S. National Science Foundation Office of Polar Programs Award No. NSF/OPP-1255058. S.J., L.L., M.M.H., Y.L., and R.J. gratefully acknowledge funding provided by US National Aeronautics and Space Administration Award No. NNX14AH74G. H.J.L., C.Y., S.J., Y.L., and R.J. gratefully acknowledge funding provided by U.S. National Science Foundation Office of Polar Programs Award No. NSF/PLR-1341548. S.J. gratefully acknowledges support from the Dalio Explore Fund