2,681 research outputs found
Volunteers In Energy Conservation -- Potential and Problems
The social and political implications of the energy crisis, while complex in nature and understanding, seem to urgently proclaim that the time for action is now. This paper is based on the premise that individual responsibility is essential. The people must act. Political decisions must be made. The people must debate what social climates are to be promoted and by what new energy systems. The key to solving the energy crisis is America\u27s people, and particularly with its youth. With people come the potential and of course, the problems. The approach of this paper will be threefold
Description strategies to make an interactive science simulation accessible
Interactive simulations are increasingly important in science education, yet most are inaccessible
to blind learners. In developing an accessible prototype of a PhET interactive science simulation, we
encountered significant challenges in providing screen reader access, including the need to: 1) describe
unpredictable event sequences, 2) cue productive interactions, and 3) to simultaneously convey multiple
changes. To address these challenges, we extended existing practices for verbal description of visual
interactive content, and we created new strategies for developing rich description for accessible
interactive science simulations
Small magellanic cloud-type interstellar dust in the milky way
It is well known that the sight line toward HD 204827 in the cluster Trumpler 37 shows a UV extinction curve that does not follow the average Galactic extinction relation. However, when a dust component, fore-ground to the cluster, is removed, the residual extinction curve is identical to that found in the SMC within the uncertainties. The curve is very steep and has little or no 2175 A bump. The position of HD 204827 in the sky is projected onto the edge of the Cepheus IRAS bubble. In addition, HD 204827 has an IRAS bow shock, indicating that it may be embedded in dust swept up by the supernova that created the IRAS bubble. Shocks due to the supernova may have led to substantial processing of this dust. The HD 204827 cloud is dense and rich in carbon molecules. The 3.4 μm feature indicating a C-H grain mantle is present in the dust toward HD 204827. The environment of the HD 204827 cloud dust may be similar to the dust associated with HD 62542, which lies on the edge of a stellar wind bubble and is also dense and rich in molecules. This sight line may be a Rosetta Stone if its environment can be related to those in the SMC having similar dust
Evidence for Pre-Existing Dust in the Bright Type IIn SN 2010jl
SN 2010jl was an extremely bright, Type IIn SNe which showed a significant IR
excess no later than 90 days after explosion. We have obtained Spitzer 3.6 and
4.5 \mum and JHK observations of SN 2010jl \sim90 days post explosion. Little
to no reddening in the host galaxy indicated that the circumstellar material
lost from the progenitor must lie in a torus inclined out of the plane of the
sky. The likely cause of the high mid-IR flux is the reprocessing of the
initial flash of the SN by pre-existing circumstellar dust. Using a 3D Monte
Carlo Radiative Transfer code, we have estimated that between 0.03-0.35 Msun of
dust exists in a circumstellar torus around the SN located 6 \times 10 ^17 cm
away from the SN and inclined between 60-80\cdot to the plane of the sky. On
day 90, we are only seeing the illumination of approximately 5% of this torus,
and expect to see an elevated IR flux from this material up until day \sim 450.
It is likely this dust was created in an LBV-like mass loss event of more than
3 Msun, which is large but consistent with other LBV progenitors such as {\eta}
Carinae.Comment: Accepted in A
Are Ti44-Producing Supernovae Exceptional?
According to standard models supernovae produce radioactive Ti, which
should be visible in gamma-rays following decay to Ca for a few
centuries. ^{44}^{44}\tau \simeq\simeq\simeq^{44}Ti gamma-ray sources, but only
one is clearly seen, the 340-year-old Cas A SNR. Furthermore, supernovae which
produce much ^{44}Ti yields, their spatial
distributions, and statistical arguments can be stretched so that this apparent
disagreement may be accommodated within reasonable expectations, or if we have
to revise some or all of the above aspects to bring expectations in agreement
with the observations. We conclude that either core collapse supernovae have
been improbably rare in the Galaxy during the past few centuries, or
^{44}^{40}^{44}$Ca.Comment: 23 pages, 14 figures, accepted for publication in Astronomy and
Astrophysics 2006. Correcting the SN type of Tycho in Table B.1. and add its
associated reference
The 1991 version of the plume impingement computer program. Volume 2: User's input guide
The Plume Impingement Program (PLIMP) is a computer code used to predict impact pressures, forces, moments, heating rates, and contamination on surfaces due to direct impingement flowfields. Typically, it has been used to analyze the effects of rocket exhaust plumes on nearby structures from ground level to the vacuum of space. The program normally uses flowfields generated by the MOC, RAMP2, SPF/2, or SFPGEN computer programs. It is capable of analyzing gaseous and gas/particle flows. A number of simple subshapes are available to model the surfaces of any structure. The original PLIMP program has been modified many times of the last 20 years. The theoretical bases for the referenced major changes, and additional undocumented changes and enhancements since 1988 are summarized in volume 1 of this report. This volume is the User's Input Guide and should be substituted for all previous guides when running the latest version of the program. This version can operate on VAX and UNIX machines with NCAR graphics ability
The 1991 version of the plume impingement computer program. Volume 1: Description
The objective of this contract was to continue development of a vacuum plume impingement evaluator to provide an analyst with a capability for rapid assessment of thruster plume impingement scenarios. The research was divided into three areas: Plume Impingement Computer Program (PLIMP) modification/validation; graphics development; and documentation in the form of a Plume Handbook and PLIMP Input Guide
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