5,807 research outputs found
Depairing field, onset temperature and the nature of the transition in cuprates
The depairing (upper critical) field in hole-doped cuprates has been
inferred from magnetization curves - measured by torque magnetometry in
fields up to 45 T. We discuss the implications of the results for the pair
binding energy, the Nernst onset temperature, fluctuations and the nature of
the Meissner transition at .Comment: 4 pages, 5 figs., proc. M2S-HTSC-VIII, Dresden 2006, Physica (in
press
FPGA Implementation of a Parameterized Fourier Synthesizer
International audienceField-Programmable Gate Array (FPGA) offers advantages for many applications, particularly where missions are complex and time performance is critical. For small-production digital acoustic synthesizers, FPGA can achieve the above-mentioned tighter system requirements with low total system costs on single chip. In this manuscript, a real-time acoustic synthesizer is implemented using Fourier series algorithm on Altera's Cyclone II FPGA chip. This work emphasizes systematic designs and parallel computations. The proposed system includes a ïŹexible processor and a parallel parameterized acoustic module. On one hand, the Nios II embedded processor, which is relatively low-speed component, is used to generate commands and conïŹgure high-speed acoustic module parameters. On the other hand, acoustic module which should require high-speed components contains 4 parallel architectures to gain high-speed simultaneous calculus of 4 independent digital timbres. Every timbre is equivalent to 16 parallel high-precision harmonic channels with 0.3 % frequency error. Experimental results corroborate the fact that a single FPGA chip can achieve complex missions and attain real-time performances
The State-of-Art of Underwater Vehicles - Theories and Applications
An autonomous underwater vehicle (AUV) is an underwater system that contains its own
power and is controlled by an onboard computer. Although many names are given to these
vehicles, such as remotely operated vehicles (ROVs), unmanned underwater vehicles
(UUVs), submersible devices, or remote controlled submarines, to name just a few, the
fundamental task for these devices is fairly well defined: The vehicle is able to follow a
predefined trajectory.
AUVs offer many advantages for performing difficult tasks submerged in water. The main
advantage of an AUV is that is does not need a human operator. Therefore it is less
expensive than a human operated vehicle and is capable of doing operations that are too
dangerous for a person. They operate in conditions and perform task that humans are not
able to do efficiently, or at all (Smallwood & Whitcomb, 2004; Horgan & Toal, 2006; Caccia,
2006)
Two-dimensional array of magnetic particles: The role of an interaction cutoff
Based on theoretical results and simulations, in two-dimensional arrangements
of a dense dipolar particle system, there are two relevant local dipole
arrangements: (1) a ferromagnetic state with dipoles organized in a triangular
lattice, and (2) an anti-ferromagnetic state with dipoles organized in a square
lattice. In order to accelerate simulation algorithms we search for the
possibility of cutting off the interaction potential. Simulations on a dipolar
two-line system lead to the observation that the ferromagnetic state is much
more sensitive to the interaction cutoff than the corresponding
anti-ferromagnetic state. For (measured in particle diameters)
there is no substantial change in the energetical balance of the ferromagnetic
and anti-ferromagnetic state and the ferromagnetic state slightly dominates
over the anti-ferromagnetic state, while the situation is changed rapidly for
lower interaction cutoff values, leading to the disappearance of the
ferromagnetic ground state. We studied the effect of bending ferromagnetic and
anti-ferromagnetic two-line systems and we observed that the cutoff has a major
impact on the energetical balance of the ferromagnetic and anti-ferromagnetic
state for . Based on our results we argue that is a
reasonable choice for dipole-dipole interaction cutoff in two-dimensional
dipolar hard sphere systems, if one is interested in local ordering.Comment: 8 page
- âŠ