998 research outputs found
Note: Optical filter method for high-resolution magnetostriction measurement using fiber Bragg grating under millisecond-pulsed high magnetic fields at cryogenic temperatures
High-resolution magnetostriction measurement of at a
speed of 5 MHz is performed, using optical filter method as the detection
scheme for the fiber Bragg grating (FBG) based strain monitor is performed
under 35-millisecond pulsed high magnetic fields up to 45 T at 2.2 K. The
resolution of magnetostriction is about the same order as the conventionally
reported value from FBG based magnetostriction measurement systems for
millisecond pulsed magnetic fields. The measurement speed is 100 times
the conventional ones. Present system can be a faster alternative for the
conventional FBG based magnetostriction measurement system for millisecond
pulsed high magnetic fields.Comment: 3 pages, 3 figure
Estimation of Dimensions Contributing to Detected Anomalies with Variational Autoencoders
Anomaly detection using dimensionality reduction has been an essential
technique for monitoring multidimensional data. Although deep learning-based
methods have been well studied for their remarkable detection performance,
their interpretability is still a problem. In this paper, we propose a novel
algorithm for estimating the dimensions contributing to the detected anomalies
by using variational autoencoders (VAEs). Our algorithm is based on an
approximative probabilistic model that considers the existence of anomalies in
the data, and by maximizing the log-likelihood, we estimate which dimensions
contribute to determining data as an anomaly. The experiments results with
benchmark datasets show that our algorithm extracts the contributing dimensions
more accurately than baseline methods
R&D Status and Plan for FPCCD VTX
Fine pixel CCD (FPCCD) is an option for the sensor used for the ILC vertex
detector to reduce the pixel occupancy due to the high background rate near the
interaction point. In this paper, we report on the R&D status of FPCCD sensors
and the R&D plan for the sensors and the cooling system.Comment: 4 pages, 3 figures, Proceedings of LCWS/ILC2010
Fluctuation-Dissipation Theory of Input-Output Interindustrial Correlations
In this study, the fluctuation-dissipation theory is invoked to shed light on
input-output interindustrial relations at a macroscopic level by its
application to IIP (indices of industrial production) data for Japan.
Statistical noise arising from finiteness of the time series data is carefully
removed by making use of the random matrix theory in an eigenvalue analysis of
the correlation matrix; as a result, two dominant eigenmodes are detected. Our
previous study successfully used these two modes to demonstrate the existence
of intrinsic business cycles. Here a correlation matrix constructed from the
two modes describes genuine interindustrial correlations in a statistically
meaningful way. Further it enables us to quantitatively discuss the
relationship between shipments of final demand goods and production of
intermediate goods in a linear response framework. We also investigate
distinctive external stimuli for the Japanese economy exerted by the current
global economic crisis. These stimuli are derived from residuals of moving
average fluctuations of the IIP remaining after subtracting the long-period
components arising from inherent business cycles. The observation reveals that
the fluctuation-dissipation theory is applicable to an economic system that is
supposed to be far from physical equilibrium.Comment: 13 pages, 13 figures and 3 table
Spin state ordering of strongly correlating LaCoO induced at ultrahigh magnetic fields
Magnetization measurements of LaCoO have been carried out up to 133 T
generated with a destructive pulse magnet at a wide temperature range from 2 to
120 K. A novel magnetic transition was found at T and
K which is characterized by its transition field increasing with increasing
temperature. At , the previously reported transition at T
was observed. Based on the obtained - phase diagram and the
Clausius-Clapeyron relation, the entropy of the high-field phase at 80 K is
found to be smaller for about J K mol than that of the
low-field phase. We suggest that the observed two high-field phases may
originate in different spatial orders of the spin states and possibly other
degrees of freedom such as orbitals. An inherent strong correlation of spin
states among cobalt sites should have triggered the emergence of the ordered
phases in LaCoO at high magnetic fields.Comment: 5 pages, 2 figure
R&D Status of FPCCD Vertex Detector for ILD
Fine pixel CCD (FPCCD) is one of the candidate sensor technologies for the
vertex detector used for experiments at the International Linear Collider
(ILC). A vertex detector system for the International Large Detector (ILD)
using FPCCD sensors has been designed. We report on the R&D status of FPCCD
sensors, as well as the vertex detector design for ILD.Comment: 5 pages, 3 figures, LCWS1
What Causes Business Cycles? Analysis of the Japanese Industrial Production Data
We explore what causes business cycles by analyzing the Japanese industrial
production data. The methods are spectral analysis and factor analysis. Using
the random matrix theory, we show that two largest eigenvalues are significant.
Taking advantage of the information revealed by disaggregated data, we identify
the first dominant factor as the aggregate demand, and the second factor as
inventory adjustment. They cannot be reasonably interpreted as technological
shocks. We also demonstrate that in terms of two dominant factors, shipments
lead production by four months. Furthermore, out-of-sample test demonstrates
that the model holds up even under the 2008-09 recession. Because a fall of
output during 2008-09 was caused by an exogenous drop in exports, it provides
another justification for identifying the first dominant factor as the
aggregate demand. All the findings suggest that the major cause of business
cycles is real demand shocks.Comment: 52 pages, 19 figures, 2 table
Two Spin-State Crystallizations in LaCoO
We report a magnetostriction study of a perovskite above 100
T using our state-of-the-art strain gauge to investigate an interplay between
electron correlations and spin crossover. There has been a controversy
regarding whether two novel phases in at high magnetic fields
result from crystallizations or Bose-Einstein condensation during spin
crossover as manifestations of localization and delocalization in spin states,
respectively. We show that both phases are crystallizations rather than
condensations, and the two crystallizations are different, based on the
observations that the two phases exhibit as magnetostriction plateaux with
distinct heights. The crystallizations of spin states have emerged manifesting
the localizations and interactions in spin crossover with large and cooperative
lattice changes.Comment: 6 pages, 6 figures in the main text, 4 pages 3 figures in the
supplemental material, to appear in Phys. Rev. Let
Magnetic-field-induced spin crossover of Y-doped PrCaCoO
The family of hole-doped Pr-based perovskite cobaltites,
PrCaCoO and
(PrRE)CaCoO (where RE is rare earth) has
recently been found to exhibit simultaneous metal-insulator, spin-state, and
valence transitions. We have investigated magnetic-field-induced phase
transitions of (PrY)CaCoO by means of
magnetization measurements at 4.2100 K up to an ultrahigh magnetic field of
140 T with the chemical pressure varied by = 0.0625, 0.075, 0.1. The
observed magnetic-field-induced transitions were found to occur simultaneously
with the metal-insulator transitions up to 100 T. The obtained magnetic
field-temperature (-) phase diagram and magnetization curves are well
analyzed by a spin-crossover model of a single ion with interion interactions.
On the other hand, the chemical pressure dependence of the experimentally
obtained magnetization change during the phase transition disagrees with the
single ion model when approaching low temperatures. The significant
dependence of the magnetization change at low temperatures may arise from the
itinerant magnetism of Co in the paramagnetic metallic phase, where the
chemical pressure enhances the exchange splitting by promoting the
double-exchange interaction. The observed - phase diagrams of
(PrY)CaCoO are quite contrary to that of
LaCoO, indicating that in (PrY)CaCoO
the high-field phase possesses higher entropy than the low-field phase, whereas
it is the other way around in LaCoO.Comment: 8 pages, 6 figure
100 MHz high-speed strain monitor using fiber Bragg grating and optical filter applied for magnetostriction measurements of cobaltite at magnetic fields beyond 100 T
High-speed 100 MHz strain monitor using fiber Bragg grating (FBG) and an
optical filter has been devised for the magnetostriction measurements under
ultrahigh magnetic fields. The longitudinal magnetostriction of LaCoO has
been measured at room temperature, 115, 7 and 4.2 K up to the maximum magnetic
field of 150 T. The field-induced lattice elongations are observed, which are
attributed to the spin-state crossover from the low-spin ground state to
excited spin-states.Comment: 4 pages, 2 figures, proceedings of SCES 201
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