375 research outputs found
Toolchain Modeling: Comprehensive Engineering Plans for Industry 4.0
The fourth industrial revolution (Industry 4.0) elevates the complexity and autonomy of industrial systems and engineering environments to levels not seen before. The novel challenges involve not only the software running on the partaking autonomous devices, but also architectural considerations and the technological infrastructure around the entire engineering process. In this paper, complementing the trends in industrial systems design, we propose an approach to toolchain modeling, i.e. an integrated specification for the interoperability of tools along with the holistic architectural framework, designed in the context of the Arrowhead Framework. In particular, we propose an intuitive, yet founded definition for toolchains and their mappings to a versatile engineering process model. Those definitions then serve as a basis for proposing our comprehensive toolchain modeling approach. The methodology is demonstrated using (simplified) real-world engineering case studies based on the Arrowhead Framework and platform
Analytical control test plan and microbiological methods for the water recovery test
Qualitative and quantitative laboratory results are important to the decision-making process. In some cases, they may represent the only basis for deciding between two or more given options or processes. Therefore, it is essential that handling of laboratory samples and analytical operations employed are performed at a deliberate level of conscientious effort. Reporting erroneous results can lead to faulty interpretations and result in misinformed decisions. This document provides analytical control specifications which will govern future test procedures related to all Water Recovery Test (WRT) Phase 3 activities to be conducted at the National Aeronautics and Space Administration/Marshall Space Flight Center (NASA/MSFC). This document addresses the process which will be used to verify analytical data generated throughout the test period, and to identify responsibilities of key personnel and participating laboratories, the chains of communication to be followed, and ensure that approved methodology and procedures are used during WRT activities. This document does not outline specifics, but provides a minimum guideline by which sampling protocols, analysis methodologies, test site operations, and laboratory operations should be developed
Gauge Field Formulation of Adiabatic Spin Torques
Previous calculation of spin torques for small-amplitude magnetization
dynamics around a uniformly magnetized state [J. Phys. Soc. Jpn. {\bf 75}
(2006) 113706] is extended here to the case of finite-amplitude dynamics. This
is achieved by introducing an `` adiabatic'' spin frame for conduction
electrons, and the associated SU(2) gauge field. In particular, the Gilbert
damping is shown to arise from the time variation of the spin-relaxation source
terms in this new frame, giving a new physical picture of the damping. The
present method will allow a `` first-principle'' derivation of spin torques
without any assumptions such as rotational symmetry in spin space.Comment: 4 pages, 3 figure
Theory of current-driven motion of Skyrmions and spirals in helical magnets
We study theoretically the dynamics of the spin textures, i.e., Skyrmion
crystal (SkX) and spiral structure (SS), in two-dimensional helical magnets
under external current. By numerically solving the Landau-Lifshitz-Gilbert
equation, it is found that (i) the critical current density of the motion is
much lower for SkX compared with SS in agreement with the recent experiment,
(ii) there is no intrinsic pinning effect for SkX and the deformation of the
internal structure of Skyrmion reduces the pinning effect dramatically, (iii)
the Bragg intensity of SkX shows strong time-dependence as can be observed by
neutron scattering experiment.Comment: 4 pages, 3 figure
Microscopic Calculation of Spin Torques in Disordered Ferromagnets
Effects of conduction electrons on magnetization dynamics, represented by
spin torques, are calculated microscopically in the first order in spatial
gradient and time derivative of magnetization. Special attention is paid to the
so-called -term and the Gilbert damping, , in the presence of
electrons' spin-relaxation processes, which are modeled by quenched magnetic
(and spin-orbit) impurities. The obtained results such as
hold for localized as well as itinerant ferromagnetism.Comment: 4 page
Dephasing Effects by Ferromagnetic Boundary on Resistivity in Disordered Metallic Layer
The resistivity of disordered metallic layer sandwiched by two ferromagnetic
layers at low-temperature is investigated theoretically. It is shown that the
magnetic field acting at the interface does not affect the classical Boltzmann
resistivity but causes a dephasing among electrons in the presence of the
spin-orbit interaction, suppressing the anti-localization due to the spin-orbit
interaction. The dephasing turns out to be stronger in the case where the
magnetization of the two layers is parallel, contributing to a positive
magnetoresistance close to a switching field at low temperature.Comment: 11 pages, 3 figures. Title modified in journal versio
Noncommutative Geometry and Geometric Phases
We have studied particle motion in generalized forms of noncommutative phase
space, that simulate monopole and other forms of Berry curvature, that can be
identified as effective internal magnetic fields, in coordinate and momentum
space. The Ahranov-Bohm effect has been considered in this form of phase space,
with operatorial structures of noncommutativity. Physical significance of our
results are also discussed.Comment: Revised version, Reference added, to appear in Euro.Phys.Let
Spin-Glass-like Transition and Hall Resistivity of Y2-xBixIr2O7
Various physical properties of the pyrochlore oxide Y2-xBixIr2O7 have been
studied. The magnetizations M measured under the conditions of the
zero-field-cooling(ZFC) and the field-cooling(FC) have different values below
the temperature T=TG. The anomalous T-dependence of the electrical
resistivities r and the thermoelectric powers S observed at around TG indicates
that the behavior of the magnetization is due to the transition to the state
with the spin freezing. In this spin-frozen state, the Hall resistivities rH
measured with the ZFC and FC conditions are found to have different values,
too, in the low temperature phase (T<TG). Possible mechanisms which induce such
the hysteretic behavior are discussed.Comment: 9 pages, 7 figures, J. Phys. Soc. Jpn. 72 (2003) No.
Anomalous Hall Effect and Skyrmion Number in Real- and Momentum-space
We study the anomalous Hall effect (AHE) for the double exchange model with
the exchange coupling being smaller than the bandwidth for the
purpose of clarifying the following unresolved and confusing issues: (i) the
effect of the underlying lattice structure, (ii) the relation between AHE and
the skyrmion number, (iii) the duality between real and momentum spaces, and
(iv) the role of the disorder scatterings; which is more essential,
(Hall conductivity) or (Hall resistivity)? Starting from a generic
expression for , we resolve all these issues and classify the regimes
in the parameter space of (: elastic-scattering time), and
(length scale of spin texture). There are two distinct mechanisms
of AHE; one is characterized by the real-space skyrmion-number, and the other
by momentum-space skyrmion-density at the Fermi level, which work in different
regimes of the parameter space.Comment: 4 pages, 1 figure, REVTe
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