6,243 research outputs found
Micromagnetic simulations of sweep-rate dependent coercivity in perpendicular recording media
The results of micromagnetic simulations are presented which examine the
impact of thermal fluctuations on sweep rate dependent coercivities of both
single-layer and exchange-coupled-composite (ECC) perpendicular magnetic
recording media. M-H loops are calculated at four temperatures and sweep rates
spanning five decades with fields applied normal to the plane and at 45
degrees. The impact of interactions between grains is evaluated. The results
indicate a significantly weaker sweep-rate dependence for ECC media suggesting
more robustness to long-term thermal effects. Fitting the modeled results to
Sharrock-like scaling proposed by Feng and Visscher [J. Appl. Phys. 95, 7043
(2004)] is successful only in the case of single-layer media with the field
normal to the plane.Comment: 7 pages, 14 figure
Apollo experience report guidance and control systems: Primary guidance, navigation, and control system development
The primary guidance, navigation, and control systems for both the lunar module and the command module are described. Development of the Apollo primary guidance systems is traced from adaptation of the Polaris Mark II system through evolution from Block I to Block II configurations; the discussion includes design concepts used, test and qualification programs performed, and major problems encountered. The major subsystems (inertial, computer, and optical) are covered. Separate sections on the inertial components (gyroscopes and accelerometers) are presented because these components represent a major contribution to the success of the primary guidance, navigation, and control system
A/r/cography: art, research and communication
This article aims at establishing the foundations for a/r/cography as an “art and communication”-based research methodology, inspired by a/r/tography yet more encompassing, and particularly suitable for the digital art world. As part of the larger family of practice-based research methodologies, a/r/tography presents various ways through which it can be explored, but since it is aimed at the arts and education, its scope is forcibly hampered by the fact that not all researchers and art practitioners are necessarily teachers. However, since most of its underlying principles can be extended for non-teachers, thus arose the idea to propose a methodology that would retain ontological, epistemological and methodological assumptions, but would expand beyond the limitations imposed by the role of the teacher. This extension is called a/r/cography and is structured upon the interchangeable roles of artist, researcher and communicator, as being intrinsic to the underlying living inquiry processes. Furthermore, this proposal is supported by the author’s own experience from a/r/cographic processes in the creation, exhibition and communication of digital artworks.info:eu-repo/semantics/publishedVersio
The Peierls substitution in an engineered lattice potential
Artificial gauge fields open new possibilities to realize quantum many-body
systems with ultracold atoms, by engineering Hamiltonians usually associated
with electronic systems. In the presence of a periodic potential, artificial
gauge fields may bring ultracold atoms closer to the quantum Hall regime. Here,
we describe a one-dimensional lattice derived purely from effective
Zeeman-shifts resulting from a combination of Raman coupling and radiofrequency
magnetic fields. In this lattice, the tunneling matrix element is generally
complex. We control both the amplitude and the phase of this tunneling
parameter, experimentally realizing the Peierls substitution for ultracold
neutral atoms.Comment: 6 pages, 5 figure
Dual-species quantum degeneracy of potassium-40 and rubidium-87 on an atom chip
In this article we review our recent experiments with a 40K-87Rb mixture. We
demonstrate rapid sympathetic cooling of a 40K-87Rb mixture to dual quantum
degeneracy on an atom chip. We also provide details on efficient BEC
production, species-selective magnetic confinement, and progress toward
integration of an optical lattice with an atom chip. The efficiency of our
evaporation allows us to reach dual degeneracy after just 6 s of evaporation -
more rapidly than in conventional magnetic traps. When optimizing evaporative
cooling for efficient evaporation of 87Rb alone we achieve BEC after just 4 s
of evaporation and an 8 s total cycle time.Comment: 8 pages, 4 figures. To be published in the Proceedings of the 20th
International Conference on Atomic Physics, 2006 (Innsbruck, Austria
- …