141 research outputs found
Magnetically induced splitting of a giant vortex state in a mesoscopic superconducting disk
The nucleation of superconductivity in a superconducting disk with a Co/Pt
magnetic triangle was studied. We demonstrate that when the applied magnetic
field is parallel to the magnetization of the triangle, the giant vortex state
of vorticity three splits into three individual F0-vortices, due to a
pronounced influence of the C3 symmetry of the magnetic triangle. As a result
of a strong pinning of the three vortices by the triangle, their configuration
remains stable in a broad range of applied magnetic fields. For sufficiently
high fields, F0-vortices merge and the nucleation occurs through the giant
vortex state. The theoretical analysis of this novel reentrant behaviour at the
phase boundary, obtained within the Ginzburg - Landau formalism, is in
excellent agreement with the experimental data.Comment: to be published in Phys. Rev. B - Rapid. Com
On the rotational dynamics of the Rattleback
The Rattleback is a very popular science toy shown to students all over the
world to demonstrate the non-triviality of rotational motion. When spun on a
horizontal table, this boat-shaped object behaves in a peculiar way. Although
the object appears symmetric, the dynamics of its motion seem very asymmetric.
When spun in the preferred direction, it spins smoothly, whereas in the other
direction it starts to oscillate wildly. The oscillation soon dies out and the
rattleback starts to spin in the preferred way. We will construct and go
through an analytical model capable of explaining this behaviour in a simple
and intelligible way. Although we aim at a semi-pedagogical treatise, we will
study the details only when they are necessary to understand the calculation.
After presenting the calculations we will discuss the physical validity of our
assumptions and take a look at more sophisticated models requiring numerical
analysis. We will then improve our model by assuming a simple friction force.Comment: 17 pages and 2 figures, typos corrected, some minor additions and
rewording
Piezoresistivity and conductance anisotropy of tunneling-percolating systems
Percolating networks based on interparticle tunneling conduction are shown to
yield a logarithmic divergent piezoresistive response close to the critical
point as long as the electrical conductivity becomes nonuniversal. At the same
time, the piezoresistivity or, equivalently, the conductivity anisotropy
exponent remains universal also when the conductive exponent is not,
suggesting a purely geometric origin of . We discuss our results in
relation to the nature of transport for a variety of materials such as
carbon-black--polymer composites and RuO_2-glass systems which show
nonuniversal transport properties and coexistence between tunneling and
percolating behaviors.Comment: 6 pages, 3 figures, Added discussion on experiment
Differences Among Health Care Settings in Utilization and Type of Physical Rehabilitation Administered to Patients Receiving Workersâ Compensation for Musculoskeletal Disorders
Hydrothermal Synthesis of Delafossite-Type Oxides
The syntheses of copper and silver delafossite-type oxides from their constituent binary metal oxides, oxide hydroxides and hydroxides, by low temperature (<210 °C) and low pressure (<20 atm) hydrothermal reactions are described. Particular emphasis is placed on how the acid-base character of a constituent oxide determines its solubility and therefore whether a particular delafossite-type oxide can be synthesized, a strategy utilized by geologists and mineralogists to understand the conditions necessary for the synthesis of various minerals. Thus, the geochemical and corrosion science literature are shown to be useful in understanding the reaction conditions required for the syntheses of delafossite-type oxides and the relationship between reactant metal oxide acid-base character, solubility, aqueous speciation, and product
formation. Manipulation of the key parameters, temperature, pressure, pH, and reactant solubility, results in broad families of phase-pure delafossite-type oxides in moderate to high yields for copper, CuBO2 (B) Al, Sc, Cr, Mn, Fe, Co, Ga, and Rh), and silver, AgBO2 (B ) Al, Sc, Fe, Co, Ni, Ga, Rh, In, and Tl)
Further Development of Surface Metrology Methods for Predicting the Functional Performance of Flexible PV Barrier Films
Surface topography analysis plays a very significant role in determining the functional performance for many engineering surfaces. In this paper, feature characterisation techniques, based on the âWolf pruningâ method are implemented to characterise micro and nano-scale features which have a dominant effect on the functional lifespan of flexible Photovoltaic (PV) modules. The densities and dimensions of the potential significant features are calculated by means of the feature âcharacterisation toolboxâ. The outcome of this study has shown the potential of areal feature segmentation for detecting functionally significant defects present in Atomic Layer Deposition (ALD) barrier coatings of Al2O3 on polymer films. The analysis provides the basis for the development in process metrology for Roll-to-Roll (R2R) production of barrier coatings as applied to flexible PV arrays and is a first step in the demonstration of in-process use of feature parameters
Preparation and Properties of Bismuth Ruthenate Thin Film Electrodes for Chlorine Evolution
âOâ2 Electrocatalysis on Thin Film Metallic Oxide Electrodes with the Delafossite Structure
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