19,602 research outputs found
The Ontological Basis of Strong Artificial Life
This article concerns the claim that it is possible to create living organisms, not merely models that represent organisms, simply by programming computers ("virtual" strong alife). I ask what sort of things these computer-generated organisms are supposed to be (where are they, and what are they made of?). I consider four possible answers to this question: (a) The organisms are abstract complexes of pure information; (b) they are material objects made of bits of computer hardware; (c) they are physical processes going on inside the computer; and (d) they are denizens of an entire artificial world, different from our own, that the programmer creates. I argue that (a) could not be right, that (c) collapses into (b), and that (d) would make strong alife either absurd or uninteresting. Thus, "virtual" strong alife amounts to the claim that, by programming a computer, one can literally bring bits of its hardware to life
Advanced thin film thermocouples
The fabrication, materials characterization, and performance of thin film platinum rhodium thermocouples on gas turbine alloys was investigated. The materials chosen for the study were the turbine blade alloy systems MAR M200+Hf with NiCoCrAlY and FeCrAlY coatings, and vane alloy systems MAR M509 with FeCrAlY. Research was focussed on making improvements in the problem areas of coating substrate stability, adhesion, and insulation reliability and durability. Diffusion profiles between the substrate and coating with and without barrier coatings of Al2O3 are reported. The relationships between fabrication parameters of thermal oxidation and sputtering of the insulator and its characterization and performance are described. The best thin film thermocouples were fabricated with the NiCoCrAlY coatings which were thermally oxidized and sputter coated with Al2O3
Devil's Staircase and Disordering Transitions in Sliding Vortices and Wigner Crystals on Random Substrates with Transverse Driving
Using numerical simulations we show that, in the presence of random quenched
disorder, sliding superconducting vortices and Wigner crystals pass through a
variety of dynamical phases when an additional transverse driving force is
applied. If the disorder is weak, the driven particles form a moving lattice
and the transverse response shows a devil's staircase structure as the net
driving force vector locks with the symmetry directions of the moving lattice,
in agreement with the predictions of Le Doussal and Giamarchi. For strong
disorder, and particularly for smoothly varying potential landscapes, the
transverse response consists of a sequence of disordering transitions with an
intervening formation of stable channel structures.Comment: 7 pages, 6 postscript figures. Version to appear in Phys. Rev.
Remote sensing of changes in morphology and physiology of trees under stress
Measurements on foliage samples collected from several drought and salt treated plants revealed that leaf thickness decreased with increasing severity of the drought treatment and increased with increasing severity of treatment with NaCl, but remained essentially unaffected by treatment with CaCl2. Airborne data collected by multispectral scanner indicated that false color images provide selective enhancement of a diseased area. Comparison of simulated and actual aerial color and color IR photography revealed that the color renditions of the MSS simulations agreed closely with those of the actual photography
Remote sensing applications in forestry - Remote sensing of changes in morphology and physiology of trees under stress Annual progress report
Remote sensing of changes in morphology and physiology of trees under stres
No well-defined remnant Fermi surface in Sr2CuO2Cl2
In angle-resolved photoelectron spectra of the antiferromagnetic insulators
Ca2CuO2Cl2 and Sr2CuO2Cl2 a sharp drop of the spectral intensity of the
lowest-lying band is observed along a line in k space equivalent to the Fermi
surface of the optimally doped high-temperature superconductors. This was
interpreted as a signature of the existence of a remnant Fermi surface in the
insulating phase of the high-temperature superconductors. In this paper it is
shown that the drop of the spectral intensity is not related to the spectral
function but is a consequence of the electron-photon matrix elementComment: 4 pages, 3 figure
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