5,620 research outputs found
Technical Efficiency in the Iron and Steel Industry: A Stochastic Frontier Approach
In this paper we examine the technical efficiency of firms in the iron and steel industry and try to identify the factors contributing to the industry's efficiency growth, using a time-varying stochastic frontier model. Based on our findings, which pertain to 52 iron and steel firms over the period of 1978-1997, POSCO and Nippon Steel were the most efficient firms, with their production, on average, exceeding 95 percent of their potential output. Our findings also shed light on possible sources of efficiency growth in the industry. If a firm is government-owned, its privatization is likely to improve its technical efficiency to a great extent. A firm's technical efficiency also tends to be positively related to its production level as measured by a share of the total world production of crude steel. Another important source of efficiency growth identified by our empirical findings is adoption of new technologies and equipment. Our findings clearly indicate that continued efforts to update technologies and equipment are critical in pursuit of efficiency in the iron and steel industry.
MuNES: Multifloor Navigation Including Elevators and Stairs
We propose a scheme called MuNES for single mapping and trajectory planning
including elevators and stairs. Optimized multifloor trajectories are important
for optimal interfloor movements of robots. However, given two or more options
of moving between floors, it is difficult to select the best trajectory because
there are no suitable indoor multifloor maps in the existing methods. To solve
this problem, MuNES creates a single multifloor map including elevators and
stairs by estimating altitude changes based on pressure data. In addition, the
proposed method performs floor-based loop detection for faster and more
accurate loop closure. The single multifloor map is then voxelized leaving only
the parts needed for trajectory planning. An optimal and realistic multifloor
trajectory is generated by exploring the voxels using an A* algorithm based on
the proposed cost function, which affects realistic factors. We tested this
algorithm using data acquired from around a campus and note that a single
accurate multifloor map could be created. Furthermore, optimal and realistic
multifloor trajectory could be found by selecting the means of motion between
floors between elevators and stairs according to factors such as the starting
point, ending point, and elevator waiting time. The code and data used in this
work are available at https://github.com/donghwijung/MuNES
Current-induced domain wall motion in a nanowire with perpendicular magnetic anisotropy
We study theoretically the current-induced magnetic domain wall motion in a
metallic nanowire with perpendicular magnetic anisotropy. The anisotropy can
reduce the critical current density of the domain wall motion. We explain the
reduction mechanism and identify the maximal reduction conditions. This result
facilitates both fundamental studies and device applications of the current-
induced domain wall motion
Spin-orbit torques from interfacial spin-orbit coupling for various interfaces
We use a perturbative approach to study the effects of interfacial spin-orbit
coupling in magnetic multilayers by treating the two-dimensional Rashba model
in a fully three-dimensional description of electron transport near an
interface. This formalism provides a compact analytic expression for
current-induced spin-orbit torques in terms of unperturbed scattering
coefficients, allowing computation of spin-orbit torques for various contexts,
by simply substituting scattering coefficients into the formulas. It applies to
calculations of spin-orbit torques for magnetic bilayers with bulk magnetism,
those with interface magnetism, a normal metal/ferromagnetic insulator
junction, and a topological insulator/ferromagnet junction. It predicts a
dampinglike component of spin-orbit torque that is distinct from any intrinsic
contribution or those that arise from particular spin relaxation mechanisms. We
discuss the effects of proximity-induced magnetism and insertion of an
additional layer and provide formulas for in-plane current, which is induced by
a perpendicular bias, anisotropic magnetoresistance, and spin memory loss in
the same formalism.Comment: 24 pages, 9 figure
Prediction of Giant Spin Motive Force due to Rashba Spin-Orbit Coupling
Magnetization dynamics in a ferromagnet can induce a spin-dependent electric
field through spin motive force. Spin current generated by the spin-dependent
electric field can in turn modify the magnetization dynamics through
spin-transfer torque. While this feedback effect is usually weak and thus
ignored, we predict that in Rashba spin-orbit coupling systems with large
Rashba parameter , the coupling generates the spin-dependent
electric field [\pm(\alpha_{\rm R}m_e/e\hbar) (\vhat{z}\times \partial
\vec{m}/\partial t)], which can be large enough to modify the magnetization
dynamics significantly. This effect should be relevant for device applications
based on ultrathin magnetic layers with strong Rashba spin-orbit coupling.Comment: 4+ pages, 2 figure
Multiple Sensor Fusion and Motion Control of Snake Robot Based on Soft-Computing
There are many circumstance limits to human like extreme radioactivity, temperature
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