217 research outputs found
FIMCAR XII: Influence on Other Impact Types
The objective of this deliverable is to describe the expected influence of the candidate test procedures developed in FIMCAR for frontal impact on other impact types. The other impact types of primary interest are front-to-side impacts, collisions with road restraint systems (e.g. guardrails), and heavy goods vehicle impacts. These collision types were chosen as they involve structures that can be adapted to improve safety. Collisions with vulnerable road users (VRU) were not explicitly investigated in FIMCAR. It is expected that the vehicle structures of interest in FIMCAR can be designed into a VRU friendly shell. Information used for this deliverable comes from simulations and car-to-car crash tests conducted in FIMCAR or review of previous research. Three test configurations (full width, offset, and moving deformable barriers) were the input to the FIMCAR selection process. There are three different types of offset tests and two different full width tests. During the project test procedures could be divided into three groups that provide different influences or outcomes on vehicle designs:
1. The ODB barrier provides a method to assess part of the vehicles energy absorption capabilities
and compartment test in one test
2. The FWRB and FWDB have similar capabilities to control structural alignment, further assess
energy absorption capabilities, and promote the improvements in the occupant restraint system
for high deceleration impacts.
3. The PDB and MPDB can be used to promote better load spreading in the vehicle structures, in
addition to assessing energy absorption and occupant compartment strength in an offset configuration.
The consortium selected the ODB and FWDB as the two best candidates for short term application in international rulemaking. The review of how all candidates would affect vehicle performance in other impacts (beside front-to-front vehicle or frontal impacts with fixed obstacles) however is reported in this deliverable to support the benefit analysis reported in FIMCAR. The grouping presented above is used to discuss all five test candidates using similarities between certain tests and thereby simplify the discussion
Detection of Coronal Mass Ejections in V471 Tauri with the Hubble Space Telescope
V471 Tauri, an eclipsing system consisting of a hot DA white dwarf (WD) and a
dK2 companion in a 12.5-hour orbit, is the prototype of the pre-cataclysmic
binaries. The late-type component is magnetically active, due to its being
constrained to rotate synchronously with the short orbital period. During a
program of UV spectroscopy of V471 Tau, carried out with the Goddard High
Resolution Spectrograph (GHRS) onboard the Hubble Space Telescope, we
serendipitously detected two episodes in which transient absorptions in the Si
III 1206 A resonance line appeared suddenly, on a timescale of <2 min. The
observations were taken in a narrow spectral region around Ly-alpha, and were
all obtained near the two quadratures of the binary orbit, i.e., at maximum
projected separation (~3.3 Rsun) of the WD and K star.
We suggest that these transient features arise when coronal mass ejections
(CME's) from the K2 dwarf pass across the line of sight to the WD. Estimates of
the velocities, densities, and masses of the events in V471 Tau are generally
consistent with the properties of solar CME's. Given our detection of 2 events
during 6.8 hr of GHRS observing, along with a consideration of the restricted
range of latitudes and longitudes on the K star's surface that can give rise to
trajectories passing in front of the WD as seen from Earth, we estimate that
the active V471 Tau dK star emits some 100-500 CME's per day, as compared to
1-3 per day for the Sun. The K dwarf's mass-loss rate associated with CME's is
at least (5-25) x 10^{-14} Msun/yr, but it may well be orders of magnitude
higher if most of the silicon is in ionization states other than Si III.Comment: 24 pages AASTeX, 4 figures. Accepted by Astrophysical Journa
Laser Welding of a Stent
We consider the problem of modelling the manufacture of a cylindrical Stent, in which layers of a plastic material are welded together by a Laser beam. We firstly set up the equations for this system and solve them by using a Finite Element method. We then look at various scalings which allow the equations to be simplified. The resulting equations are then solved analytically to obtain approximate solutions to the radial temperature profile and the averaged axial temperature profile
Deep-Channel uses deep neural networks to detect single-molecule events from patch-clamp data
Single-molecule research techniques such as patch-clamp electrophysiology deliver unique biological insight by capturing the movement of individual proteins in real time, unobscured by whole-cell ensemble averaging. The critical first step in analysis is event detection, so called “idealisation”, where noisy raw data are turned into discrete records of protein movement. To date there have been practical limitations in patch-clamp data idealisation; high quality idealisation is typically laborious and becomes infeasible and subjective with complex biological data containing many distinct native single-ion channel proteins gating simultaneously. Here, we show a deep learning model based on convolutional neural networks and long short-term memory architecture can automatically idealise complex single molecule activity more accurately and faster than traditional methods. There are no parameters to set; baseline, channel amplitude or numbers of channels for example. We believe this approach could revolutionise the unsupervised automatic detection of single-molecule transition events in the future
Calibrating Focused Light-Field Cameras Using Plenoptic Disc Features
This paper proposes a new method for estimating calibration
parameters of plenoptic cameras by minimizing the
nonlinear plenoptic reprojection error. Novel plenoptic feature
types are proposed as data for the calibration method.
These plenoptic disc features are in a natural one-to-one
correspondence with physical points in front of the camera.
We exploit the intrinsic geometry of plenoptic cameras
in a novel projection model that relates the plenoptic disc
features to physical points. The resulting calibration quality,
as quantified by mean reprojection error and 3D reconstruction
error, outperforms recently published results
PG 2131+066: A Test of Pre-White Dwarf Asteroseismology
PG 2131+066 is a composite-spectrum binary with a hot pulsating PG 1159-type
pre-white dwarf and an early M-type main sequence star. Analysis of Whole Earth
Telescope observations of the pulsating pre-white dwarf component provided an
asteroseismological determination of its mass, luminosity, and effective
temperature. These determinations allowed Kawaler et al. (1995) to determine
the distance to this star. In this paper, we refine the asteroseismological
distance determination, and confirm the distance by an independent measurement
to the system via the spectroscopic parallax of the M star. PG 2131+066 was
observed by the HST using the original PC in September 1993. Exposures with
filters F785LP and F555W both showed the companion at a distance of 0.3 arc
seconds. Photometry of the images provides an apparent magnitude for the main
sequence companion of v=18.97+/-0.15, from which we find a distance of 560
(+200 -134) pc. We also recalculated the asteroseismological distance to the
pre-white dwarf using updated models and new spectroscopic constraints from UV
spectra. The new seismological distance is 668 (+78 -83) pc, in satisfactory
agreement with the distance of the secondary star. These results suggest that
this is indeed a physical binary, and that seismological distance determination
may be the best way to determine the distance to the pulsating hot pre-white
dwarf stars.Comment: 13 pages, 4 figures, to appear in The Astrophysical Journal, Dec.10,
200
FIRST J102347.6+003841: The First Radio-Selected Cataclysmic Variable
We have identified the 1.4 GHz radio source FIRST J102347.6+003841 (hereafter
FIRST J1023+0038) with a previously unknown 17th-mag Galactic cataclysmic
variable (CV). The optical spectrum resembles that of a magnetic (AM Herculis-
or DQ Herculis-type) CV. Five nights of optical CCD photometry showed
variations on timescales of minutes to hours, along with rapid flickering. A
re-examination of the FIRST radio survey data reveals that the radio detection
was based on a single 6.6 mJy flare; on two other occasions the source was
below the ~1 mJy survey limit. Several other magnetic CVs are known to be
variable radio sources, suggesting that FIRST J1023+0038 is a new member of
this class (and the first CV to be discovered on the basis of radio emission).
However, FIRST J1023+0038 is several optical magnitudes fainter than the other
radio-detected magnetic CVs. It remains unclear whether the source simply had a
very rare and extraordinarily intense radio flare at the time of the FIRST
observation, or is really an unusually radio-luminous CV; thus further
observations are urged.Comment: 4 pages, 3 figures; accepted for December 2002 issue of Publications
of the Astronomical Society of the Pacifi
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