228,888 research outputs found
Axel: A Minimalist Tethered Rover for Exploration of Extreme Planetary Terrains
Recent scientific findings suggest that some of the most interesting sites for future exploration of planetary surfaces lie in terrains that are currently inaccessible to conventional robotic rovers. To provide robust and flexible access to these terrains, we have been developing Axel, the robotic rover. Axel is a lightweight two-wheeled vehicle that can access steep terrains and negotiate relatively large obstacles because of its actively managed tether and novel wheel design. This article reviews the Axel system and focuses on those system components that affect Axel's steep terrain mobility. Experimental demonstrations of Axel on sloped and rocky terrains are presented
Babette\u27s Feast: The Persistence of Love
In lieu of an abstract, below is the essay\u27s first paragraph.
After one\u27s first viewing of Babette\u27s Feast, a film by Gabriel Axel, one may easily think that the main point of the film revolves around interpretation of religion and food. Although these certainly are two major aspects, I personally found that in many ways, love and the way it persists through time is a major feature of the movie as well. Thanks to Axel, the movie can be viewed through the lends of love, and as the plot unfolds, it becomes more obvious that the persistence of love is a point Axel wanted to send to his audience
Wheel Design and Tension Analysis for the Tethered Axel Rover on Extreme Terrain
As the Mars Exploration rovers have reaffirmed,
some of the most interesting sites for scientists to explore on planetary surfaces lie in terrains that are currently
inaccessible to state-of-the art rovers. We have been
developing the Axel rover as a robotic platform to access
steep and challenging terrain. We will summarize the recent
mechanical upgrades since we introduced the tethered Axel
concept last year
Busse, Ulrich & Hübler, Axel (2012) Investigations into the Meta-Communicative Lexicon of English
Se trata de una reseña de Busse, Ulrich & Hübler, Axel (2012): Investigations into the Meta-Communicative Lexicon of English
Decay theory of double giant resonances
The decay theory of double giant resonances incorporating fluctuation
contributions of the Brink-Axel type is developed. The gamma and neutron
emission decay of Double Giant Dipole Resonances (DGDR) in 208Pb is discussed
in connection with a recent measurement.Comment: 5 pages, Late
Multiple giant resonances in nuclei: their excitation and decay
The excitation of multiphonon giant resonances with heavy ions is discussed.
The conventional theory, based on the use of the virtual photon number method
in conjunction with the harmonic model is presented and its shortcomings are
discussed. The recently developed model that invoke the Brink-Axel mechanism as
an important contribution to the cross-section is discussed and compared to the
conventional, harmonic model. The decay properties of these multiple giant
resonances are also discussed within the same coherent + fluctuation model in
conjunction with the hybrid decay model. It is demonstrated that the Brink-Axel
mechanism enhances the direct decay of the states, as data seem to require.
Comparison of our model with other recent theoretical works is presented.Comment: 12 pages, four figures, two tables. Invited talk at the International
Conference on Collective Motion in Nuclei Under Extreme Conditions (COMEX1),
Paris, France, 10-13 June 200
Max Dehn, Axel Thue, and the Undecidable
This is a short essay on the roles of Max Dehn and Axel Thue in the
formulation of the word problem for (semi)groups, and the story of the proofs
showing that the word problem is undecidable.Comment: Definition of undecidability and unsolvability improve
Modification of the Brink-Axel Hypothesis for High Temperature Nuclear Weak Interactions
We present shell model calculations of electron capture strength
distributions in A=28 nuclei and computations of the corresponding capture
rates in supernova core conditions. We find that in these nuclei the Brink-Axel
hypothesis for the distribution of Gamow-Teller strength fails at low and
moderate initial excitation energy, but may be a valid tool at high excitation.
The redistribution of GT strength at high initial excitation may affect capture
rates during collapse. If these trends which we have found in lighter nuclei
also apply for the heavier nuclei which provide the principal channels for
neutronization during stellar collapse, then there could be two implications
for supernova core electron capture physics. First, a modified Brink-Axel
hypothesis could be a valid approximation for use in collapse codes. Second,
the electron capture strength may be moved down significantly in transition
energy, which would likely have the effect of increasing the overall electron
capture rate during stellar collapse.Comment: 15 pages, 19 figure
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