Model support roll balance and roll coupling

The design concepts of two specialized wind tunnel model support mechanisms are described. The forced oscillation roll balance mechanism was designed to meet the specific requirement to measure aerodynamic forces and moments to permit determination of the damping-in-roll parameters of winged configurations. A variable speed motor is used to oscillate the model by means of an offset crank. The oscillating motion is resisted by a torsion spring to provide a restoring torque and is attached to the section forward of the strain-gage balance. This spring action allows the model to be oscillated at a frequency for velocity resonance, whereby the mechanical spring and any aerodynamic spring balance. This spring action allows the model to be oscillated at a frequency for velocity resonance, whereby the mechanical spring and any aerodynamic spring balance out the model inertia. The only torque then required to oscillate the model at that particular frequency is equal to that due to aerodynamic damping. The second mechanism, a roll coupling for remotely rotating a model, was designed to invert or roll a model about its longitudinal axis when mounted for testing

New Scale Factor Measure

The computation of probabilities in an eternally inflating universe requires a regulator or "measure". The scale factor time measure truncates the universe when a congruence of timelike geodesics has expanded by a fixed volume factor. This definition breaks down if the generating congruence is contracting---a serious limitation that excludes from consideration gravitationally bound regions such as our own. Here we propose a closely related regulator which is well-defined in the entire spacetime. The New Scale Factor Cutoff restricts to events with scale factor below a given value. Since the scale factor vanishes at caustics and crunches, this cutoff always includes an infinite number of disconnected future regions. We show that this does not lead to divergences. The resulting measure combines desirable features of the old scale factor cutoff and of the light-cone time cutoff, while eliminating some of the disadvantages of each.Comment: 20 pages, 1 figure; v2: references adde

Light Deflection, Lensing, and Time Delays from Gravitational Potentials and Fermat's Principle in the Presence of a Cosmological Constant

The contribution of the cosmological constant to the deflection angle and the time delays are derived from the integration of the gravitational potential as well as from Fermat's Principle. The findings are in agreement with recent results using exact solutions to Einstein's equations and reproduce precisely the new $\Lambda$-term in the bending angle and the lens equation. The consequences on time delay expressions are explored. While it is known that $\Lambda$ contributes to the gravitational time delay, it is shown here that a new $\Lambda$-term appears in the geometrical time delay as well. Although these newly derived terms are perhaps small for current observations, they do not cancel out as previously claimed. Moreover, as shown before, at galaxy cluster scale, the $\Lambda$ contribution can be larger than the second-order term in the Einstein deflection angle for several cluster lens systems.Comment: 6 pages, 1 figure, matches version published in PR

Photovoltaic module encapsulation design and materials selection, volume 1

Encapsulation material system requirements, material selection criteria, and the status and properties of encapsulation materials and processes available are presented. Technical and economic goals established for photovoltaic modules and encapsulation systems and their status are described. Available encapsulation technology and data are presented to facilitate design and material selection for silicon flat plate photovoltaic modules, using the best materials available and processes optimized for specific power applications and geographic sites. The operational and environmental loads that encapsulation system functional requirements and candidate design concepts and materials that are identified to have the best potential to meet the cost and performance goals for the flat plate solar array project are described. Available data on encapsulant material properties, fabrication processing, and module life and durability characteristics are presented

Ground-based measurements of O3, NO2, OClO, and BrO during the 1987 Antarctic ozone depletion event

Near-ultraviolet absorption spectroscopy in the wavelength range from 330 to 370 nm was used to measure O3, NO2, OClO, and BrO at McMurdo Station (78S) during 1987. Visible absorption measurements of O3, NO2, and OClO were also obtained using the wavelength range from about 403 to 453 nm. These data are described and compared to observations obtained in 1986. It is shown that comparisons of observations in the two wavelength ranges provide a sensitive measure of the altitude where the bulk of atmospheric absorption takes place

Theoretic Limits on the Equation of State Parameter of Quintessence

The value of scalar field coupled to gravity should be less than the Planck scale in the consistent theory of quantum gravity. It provides a theoretic constraint on the equation of state parameter for the quintessence. In some cases our theoretic constraints are more stringent than the constraints from the present experiments.Comment: 4 pages, 2 figures; minor corrections and refs adde

Neutron Star Properties with Hyperons

In the light of the recent discovery of a neutron star with a mass accurately determined to be almost two solar masses, it has been suggested that hyperons cannot play a role in the equation of state of dense matter in $\beta$-equilibrium. We re-examine this issue in the most recent development of the quark-meson coupling model. Within a relativistic Hartree-Fock approach and including the full tensor structure at the vector-meson-baryon vertices, we find that not only must hyperons appear in matter at the densities relevant to such a massive star but that the maximum mass predicted is completely consistent with the observation.Comment: Minor correction

Employment and Study Outcomes After Graduation An Australian Higher Education Equity Perspective

However, graduates from low socioeconomic backgrounds, who were Aboriginal or Torres Strait Islanders, or who were from non-English speaking backgrounds were found to be disadvantaged in the labour market, and policy action to address this ...Higher education policy in Australia has contributed to positive outcomes for equity groups, in terms of facilitating access, participation and completion of university. At the same time, prior research has indicated that labour market outcomes are comparable for graduates from equity groups to their non-equity counterparts. It is unknown, however, whether graduates from disadvantaged backgrounds have equitable outcomes in terms of participation in further study after the completion of their undergraduate degree. Given that research findings indicate superior earnings and positive labour market outcomes for postgraduates, it is of policy interest to examine post-study pathways for disadvantaged individuals, in comparison with their relatively privileged peers. This study uses data from the 2016 Australian Graduate Outcomes Survey, linked to student administrative records from 19 participating Australian universities, to examine post-degree study and employment outcomes. In particular, the study looks at how equity group membership, undergraduate degree characteristics, and undergraduate academic performance influences post-degree study and employment outcomes. The results from the multivariate analyses indicate that graduates from a low socioeconomic status (SES) background, or with disability, or from a non-English speaking background (NESB) were less likely to be in employment post-degree, relative to their respective counterparts. The estimated reduced propensity of employment for these groups were rather sizable, and were up to 16 per cent less for NESB graduates. However, in terms of further study post-degree, graduates from all equity groups, with the exception of graduates from regional and remote areas, were around two to five per cent more likely to be in further study after their undergraduate degrees were completed, relative to graduates from non-disadvantaged backgrounds. In addition, academic ability, as proxied by Weighted Average Marks, and undergraduate degree field of study areas were found to be influential on the graduates’ propensity to be in further study or employment. Furthermore, graduates from the equity groups of low SES background, disability and NESB were found to be disadvantaged in labour market outcomes. For example, they were less likely to be in full-time employment, more likely to be mismatched in their jobs if there were employed, and earned less. In particular, graduates from NESB backgrounds were the most disadvantaged in these labour market outcomes. Despite poor labour market outcomes for the stated equity groups, the findings from this study are encouraging for postgraduate study for students from disadvantaged backgrounds. From the perspective of higher education participation, participation in further study, including postgraduate courses, appear to be accessible for individuals from equity backgrounds. Therefore, more needs to be done from the perspective of ensuring equitable employment outcomes, especially for students from equity backgrounds as they enter employment after post-graduate study

Hands-on Gravitational Wave Astronomy: Extracting astrophysical information from simulated signals

In this paper we introduce a hands-on activity in which introductory astronomy students act as gravitational wave astronomers by extracting information from simulated gravitational wave signals. The process mimics the way true gravitational wave analysis will be handled by using plots of a pure gravitational wave signal. The students directly measure the properties of the simulated signal, and use these measurements to evaluate standard formulae for astrophysical source parameters. An exercise based on the discussion in this paper has been written and made publicly available online for use in introductory laboratory courses.Comment: 5 pages, 4 figures; submitted to Am. J. Phy