631 research outputs found
TernausNetV2: Fully Convolutional Network for Instance Segmentation
The most common approaches to instance segmentation are complex and use
two-stage networks with object proposals, conditional random-fields, template
matching or recurrent neural networks. In this work we present TernausNetV2 - a
simple fully convolutional network that allows extracting objects from a
high-resolution satellite imagery on an instance level. The network has popular
encoder-decoder type of architecture with skip connections but has a few
essential modifications that allows using for semantic as well as for instance
segmentation tasks. This approach is universal and allows to extend any network
that has been successfully applied for semantic segmentation to perform
instance segmentation task. In addition, we generalize network encoder that was
pre-trained for RGB images to use additional input channels. It makes possible
to use transfer learning from visual to a wider spectral range. For
DeepGlobe-CVPR 2018 building detection sub-challenge, based on public
leaderboard score, our approach shows superior performance in comparison to
other methods. The source code corresponding pre-trained weights are publicly
available at https://github.com/ternaus/TernausNetV
Interplay of bulk and interface effects in the electric-field driven transition in magnetite
Contact effects in devices incorporating strongly-correlated electronic
materials are comparatively unexplored. We have investigated the
electrically-driven phase transition in magnetite (100) thin films by
four-terminal methods. In the lateral configuration, the channel length is less
than 2 m, and voltage-probe wires 100 nm in width are directly
patterned within the channel. Multilead measurements quantitatively separate
the contributions of each electrode interface and the magnetite channel. We
demonstrate that on the onset of the transition contact resistances at both
source and drain electrodes and the resistance of magnetite channel decrease
abruptly. Temperature dependent electrical measurements below the Verwey
temperature indicate thermally activated transport over the charge gap. The
behavior of the magnetite system at a transition point is consistent with a
theoretically predicted transition mechanism of charge gap closure by electric
field.Comment: 6 pages, 5 figures, to appear in PR
Self-assembly of iron nanoclusters on the Fe3O4(111) superstructured surface
We report on the self-organized growth of a regular array of Fe nanoclusters
on a nanopatterned magnetite surface. Under oxidizing preparation conditions
the (111) surface of magnetite exhibits a regular superstructure with
three-fold symmetry and a 42 A periodicity. This superstructure represents an
oxygen terminated (111) surface, which is reconstructed to form a periodically
strained surface. This strain patterned surface has been used as a template for
the growth of an ultrathin metal film. A Fe film of 0.5 A thickness was
deposited on the substrate at room temperature. Fe nanoclusters are formed on
top of the surface superstructure creating a regular array with the period of
the superstructure. We also demonstrate that at least the initial stage of Fe
growth occurs in two-dimensional mode. In the areas of the surface where the
strain pattern is not formed, random nucleation of Fe was observed.Comment: 6 pages, 3 figure
Nanogaps with very large aspect ratios for electrical measurements
For nanoscale electrical characterization and device fabrication it is often
desirable to fabricate planar metal electrodes separated by large aspect ratio
gaps with interelectrode distances well below 100 nm. We demonstrate a
self-aligned process to accomplish this goal using a thin Cr film as a
sacrificial etch layer. The resulting gaps can be as small as 10 nm and have
aspect ratios exceeding 1000, with excellent interelectrode isolation. Such
Ti/Au electrodes are demonstrated on Si substrates and are used to examine a
voltage-driven transition in magnetite nanostructures. This shows the utility
of this fabrication approach even with relatively reactive substrates.Comment: 4 pages, 4 figure
Ferrimagnetism of the magnetoelectric compound CuOSeO probed by Se NMR
We present a thorough Se NMR study of a single crystal of the
magnetoelectric compound CuOSeO. The temperature dependence of the
local electronic moments extracted from the NMR data is fully consistent with a
magnetic phase transition from the high-T paramagnetic phase to a low-T
ferrimagnetic state with 3/4 of the Cu ions aligned parallel and 1/4
aligned antiparallel to the applied field of 14.09 T. The transition to this
3up-1down magnetic state is not accompanied by any splitting of the NMR lines
or any abrupt modification in their broadening, hence there is no observable
reduction of the crystalline symmetry from its high-T cubic \textit{P}23
space group. These results are in agreement with high resolution x-ray
diffraction and magnetization data on powder samples reported previously by Bos
{\it et al.} [Phys. Rev. B, {\bf 78}, 094416 (2008)]. We also develop a mean
field theory description of the problem based on a microscopic spin Hamiltonian
with one antiferromagnetic ( K) and one ferromagnetic
( K) nearest-neighbor exchange interaction
The structural and parametrical organization of elements of a power supply system in the conditions of network centrism
Purpose. Development of indicators of the structural and parametrical organization of effective active and adaptive system of service of power supply systems in the conditions of ideology of Smart Grid. Methodology. In the conditions of application of ideology of Smart Grid for increase of intellectualization of electrical power system there is a need of introduction of the principle of a network centrism in the structural and parametrical organization of elements of power supply systems that involves performance of conditions on implementation of provisions of the principle of Situational Awareness. The essence of this principle consists in that, information on a condition of system has to be presented in the form convenient for the analysis, recognition, transfer, distribution and storage, to be coordinated for flexible and optimum development at the subsystem and object-by-object levels. Results. Structural and parametrical optimization of elements of power supply systems in the conditions of a network centrism and the concept of SG involves use of provisions of the theory of systems and concepts of multicriteria optimizing synthesis. It is offered to use the modified adaptive indicator of the generalizing effect of synthesis of structure of active and adaptive system of service of power supply systems in the form of a difference of the generalizing effects: the introduced option of structure of system and basic. Originality. Introduction of an adaptive indicator of synthesis of system of service of power supply systems considers the concept of Β«service of system on the basis of a responseΒ» in the presence of false and true refusals. Practical value. Use of the specified indicator will allow to specify procedure of selection of competitive options for the purpose of definition of a set of admissible structures which meet the requirements of criterion function.Π ΡΡΠ°ΡΡΠ΅ ΡΠ°ΡΡΠΌΠΎΡΡΠ΅Π½Ρ ΡΠ΅Π½Π΄Π΅Π½ΡΠΈΠΈ ΡΠ°Π·Π²ΠΈΡΠΈΡ ΠΈ ΠΏΡΠΈΠ½ΡΠΈΠΏΡ ΠΎΡΠ³Π°Π½ΠΈΠ·Π°ΡΠΈΠΈ ΠΈΠ½ΡΠ΅Π»Π»Π΅ΠΊΡΡΠ°Π»ΡΠ½ΡΡ
ΡΠ½Π΅ΡΠ³ΠΎΡΠΈΡΡΠ΅ΠΌ ΠΏΡΠΈ Π²Π²Π΅Π΄Π΅Π½ΠΈΠΈ ΠΏΠΎΠ½ΡΡΠΈΡ ΡΠ΅ΡΠ΅ΡΠ΅Π½ΡΡΠΈΠ·ΠΌΠ° Π² ΡΡΠ»ΠΎΠ²ΠΈΡΡ
ΠΈΠ΄Π΅ΠΎΠ»ΠΎΠ³ΠΈΠΈ Smart Grid. Π ΠΊΠ°ΡΠ΅ΡΡΠ²Π΅ ΡΠ΅ΡΠ΅Π½ΠΈΡ Π·Π°Π΄Π°Ρ ΡΠΊΠ°Π·Π°Π½Π½ΠΎΠΉ ΠΏΡΠΎΠ±Π»Π΅ΠΌΠ°ΡΠΈΠΊΠΈ ΠΏΡΠ΅Π΄Π»Π°Π³Π°Π΅ΡΡΡ ΡΠΎΠ·Π΄Π°Π½ΠΈΠ΅ Π°ΠΊΡΠΈΠ²Π½ΠΎ-Π°Π΄Π°ΠΏΡΠΈΠ²Π½ΠΎΠΉ ΡΠΈΡΡΠ΅ΠΌΡ, ΡΠ΅Π°Π»ΠΈΠ·ΡΡΡΠ΅ΠΉ ΠΊΠΎΠ½ΡΠ΅ΠΏΡΠΈΡ Β«ΠΎΠ±ΡΠ»ΡΠΆΠΈΠ²Π°Π½ΠΈΡ ΡΠΈΡΡΠ΅ΠΌΡ Π½Π° ΠΎΡΠ½ΠΎΠ²Π΅ ΠΎΡΠΊΠ»ΠΈΠΊΠ°Β»
Atomically Resolved Spin-Dependent Tunnelling on the Oxygen-Terminated Fe3O4 (111)
We employ spin-polarized (SP) STM to study the spin-dependent tunneling
between a magnetite (111) sample and an antiferromagnetic tip through a vacuum
barrier at room temperature. Atomic scale STM images show significant magnetic
contrast corresponding to variations in the local surface states induced by
oxygen vacancies. The estimated variations in tunneling magnetoresistance (TMR)
of 250% suggest that the spin-transport properties are significantly altered
locally by the presence of surface defects.Comment: 10 pages, 4 figure
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