21,075 research outputs found
A New NASTRAN Capability for Data Reduction
A new module, MODB, for the data reduction of NASTRAN results is described. NASTRAN analysis results can be filtered and sorted for minimum/maximum values and the printed output resulting from large NASTRAN runs can be limited based on a number of available user options. The sorting is done on stresses, forces and vector quantities like displacements, velocity, and acceleration. The module can be accessed via DMAP alters to existing rigid formats, and has been used on a large number of statics and dynamics problems resulting in considerable savings in cost, time, and the amount of printing
Evaluation of Safety of Reinforced Concrete Buildings to Earthquakes
National Science Foundation Grant GK-3637
In-vehicle vibration study of child safety seats
This paper reports experimental measurements of the in-vehicle vibrational behaviour of stage 0&1
child safety seats. Road tests were performed for eight combinations of child, child seat and
automobile. Four accelerometers were installed in the vehicles and orientated to measure as closely
as possible in the vertical direction; two were attached to the floor and two located at the human
interfaces. An SAE pad was placed under the ischial tuberosities of the driver at the seat cushion
and a child pad, designed for the purpose of this study, was placed under the child. 4 test runs were
made over a pave’ (cobblestone) surface for the driver’s seat and 4 for the child seat at both 20 km/h and 40 km/h. Power spectral densities were determined for all measurement points and
acceleration transmissibility functions (ATFs) were estimated from the floor of the vehicle to the
human interfaces. The system composed of automobile seat, child seat and child was found to
transmit greater vibration than the system composed of automobile seat and driver. The ensemble
mean transmissibility in the frequency range from 1 to 60 Hz was found to be 77% for the child seat
systems as opposed to 61% for the driver’s seats. The acceleration transmissibility for the child seat
system was found to be higher than that of the driver’s seat at most frequencies above 10 Hz for all
eight systems tested. The measured ATFs suggest that the principal whole-body vibration resonance
of the children occurred at a mean frequency of 8.5, rather than the 3.5 to 5.0 Hz typically found in the case of seated adults. It can be concluded that current belt-fastened child seats are less effective
than the vehicle primary seating systems in attenuating vibrational disturbances. The results also
suggest the potential inability of evaluating child comfort by means of existing whole-body
vibration standards
An Unusual Application of NASTRAN Contour Plotting Capability
A procedure is presented for obtaining contour plots of any physical quantity defined on a number of points of the surface of a structure. Rigid Format 1 of HEAT approach in Cosmic NASTRAN is ALTERED to enable use of contour plotting capability for scalar quantities. The ALTERED DMAP sequence is given. Examples include temperature distribution on the face of a cooled laser mirror and the angle of incidence or a radome surface
Seyfert galaxies with Swift: giant flares, rapid drops, and other surprises
Swift has initiated a new era of understanding the extremes of active
galactic nuclei (AGN) variability, their drivers and underlying physics. This
is based on its rapid response, high sensitivity, good spatial resolution, and
its ability to collect simultaneously X--ray-to-optical SEDs. Here, we present
results from our recent monitoring campaigns with Swift of highly variable AGN,
including outbursts, deep low states, and unusual long-term trends in several
Seyfert galaxies including Mrk 335, WPVS007, and RXJ2314.9+2243. We also report
detection of a new X-ray and optical outburst of IC 3599 and our Swift
follow-ups. IC 3599 was previously known as one of the AGN with the
highest-amplitude outbursts. We briefly discuss implications of this second
outburst of IC 3599 for emission scenarios including accretion-disk
variability, repeat tidal disruption events, and the presence of a binary
supermassive black hole.Comment: to appear in "Swift: 10 years of discovery", Proceedings of Scienc
Fiedler,Marées,Hildebrand:la questione dell'antico e del moderno,il rapporto con l'impressionismo
Il rapporto che il pittore Hans von Marées, lo scultore Adolf von Hildebrand e il teorico dell'arte Konrad Fiedler stabilirono con l'Impressionismo appare a prima vista di critica e di opposizione. Ma è interessante che dall'analisi condotta emerga come sia questo gruppo di artisti e studiosi tedeschi che gli impressionisti facessero riferimento alle medesime fonti scientifiche riguardo ai processi percettivi della visione e come anche se in modo diverso rendessero entrambi il processo percettivo il medium della elaborazione del linguaggio artistico. Il saggio interroga anche il ruolo della filosofia di Schopenhauer sia riguardo alla formazione delle idee di Fiedler che di quelle di Mallarmé in rapporto a Manet e agli impressionisti
Forced vibration analysis of rotating cyclic structures in NASTRAN
A new capability was added to the general purpose finite element program NASTRAN Level 17.7 to conduct forced vibration analysis of tuned cyclic structures rotating about their axis of symmetry. The effects of Coriolis and centripetal accelerations together with those due to linear acceleration of the axis of rotation were included. The theoretical, user's, programmer's and demonstration manuals for this new capability are presented
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