104 research outputs found
Separation of PRMMC into matrix alloy and reinforcements by nozzle filtering method
The SiCP/Al?4 mass%Cu alloy composites fabricated by a low-pressure infiltration process (LPI process) were remelted and separated by nozzle filtering method. In the separation process, the PRMMC specimen was placed in a container with a small nozzle at the bottom. The molten PRMMC was forced to flow out through the nozzle by applying a certain pressure of Ar gas. Most of the molten matrix alloy flowed out through the nozzle and the remainder in the container consisted of SiC particles and a part of the matrix alloy. The particle volume fraction of the remainder was higher than that of the original PRMMC and the remainder would work as a filter to separate SiC particles from the matrix alloy melt. When nozzle tip angle was ranged from 60° to 120°, about 80% of matrix alloy in the PRMMC was separated and few SiC particles were observed in the separated matrix alloy. The surface of recovered SiC particles became slightly roughened due to the reaction with the molten matrix during the separation process. However, this is not expected to affect their reuse
Effect of Alumina Fibers on Fabrication Process and Characteristics of Alumina Fiber Reinforced Aluminum Alloy Composites
In order to develop the alumina fiber reinforcements optimized to FRMMCs, the effect of characteristics of alumina fibers on the fabrication process and the characteristics of the alumina fiber reinforced Al alloy composites was investigated. Alumina fibers which have different alumina content were prepared. Alumina content in the fibers was varied from 80% to 100%. Al-4mass%Cu alloy, Al-12mass%Si alloy and Al-10masss%Mg alloy were used as matrix. The FRMMC specimens were fabricated by a low-pressure infiltration process (LPI process). The formability of the preform was improved with increasing alumina content in the fibers. However, broken fibers were observed in the preform when alumina fibers with high alumina content were used. The number of the broken fibers seemed to be increased with increasing alumina content in the fibers. This result could be attributable to a change of fiber strength resulting from a change of alumina content in the fiber. The FRMMC specimens were characterized by using Vickers hardness test. The Vickers hardness of FRMMC specimens depended on the elasticity or the hardness of the fibers. The results obtained suggest that the characteristics of the FRMMCs largely depend on the intrinsic characteristics of the reinforcement fibers.6th International Conference on Processing and Manufacturing of Advanced Materials - THERMEC\u272009; Berlin; 25 August 2009 through 29 August 2009; Code 7924
Electrodeposition of Ferromagnetic Metal Nanowires
Ni-Fe alloy films and nanowires were fabricated using electrodeposition technique. The cylindrical shape of nanowires was precisely transferred from the nanochannels of membrane filters and the aspect ratio reached to around 60. Coercive force in in-plan direction of Ni-Fe alloy films decreased to ca. 1 Oe with increasing Fe content in deposits while, in perpendicular direction, the films were hardly magnetized. Magnetic hysteresis loops revealed that the nanowires were spontaneously magnetized to the long axis direction and the coercive force reached to ca. 200 Oe.6th International Conference on Processing and Manufacturing of Advanced Materials - THERMEC\u272009; Berlin; 25 August 2009 through 29 August 2009; Code 7924
The Subaru Deep Field Project: Lyman Emitters at Redshift of 6.6
We present new results of a deep optical imaging survey using a narrowband
filter () centered at 9196 \AA ~ together with , ,
, , and broadband filters in the sky area of the Subaru
Deep Field which has been promoted as one of legacy programs of the 8.2m Subaru
Telescope. We obtained a photometric sample of 58 Ly emitter candidates
at 6.5 -- 6.6 among strong -excess () objects together with a color criterion of . We then obtained optical spectra of 20 objects in our -excess
sample and identified at least nine Ly emitters at -- 6.6
including the two emitters reported by Kodaira et al. (2003). Since our
Ly emitter candidates are free from strong amplification of
gravitational lensing, we are able to discuss their observational properties
from a statistical point of view. Based on these new results, we obtain a lower
limit of the star formation rate density of yr Mpc at , being
consistent with our previous estimate. We discuss the nature of star-formation
activity in galaxies beyond .Comment: 49 pages, 16 figures, PASJ, Vol. 57, No. 1, in pres
Neutron capture cross section measurements of 120
Preliminary neutron capture cross section of 120Sn, 122Sn and 124Sn were obtained in the energy range from 20 meV to 4 keV with the array of germanium detectors in ANNRI at MLF,J-PARC. The results of 120Sn, 122Sn and 124Sn were obtained by normalizing the relative cross sections to the data in JENDL-4.0 at the largest 426.7-, 107.0- and 62.05-eV resonances, respectively. The 67.32- and 150-eV resonances for 120Sn and the 579- and 950-eV resonances for 124Sn which are listed in JENDL-4.0 and/or ENDF/B VII.1 were not observed
Clustering of Lyman Break Galaxies at z=4 and 5 in The Subaru Deep Field: Luminosity Dependence of The Correlation Function Slope
We explored the clustering properties of Lyman Break Galaxies (LBGs) at z=4
and 5 with an angular two-point correlation function on the basis of the very
deep and wide Subaru Deep Field data. We found an apparent dependence of the
correlation function slope on UV luminosity for LBGs at both z=4 and 5. More
luminous LBGs have a steeper correlation function. To compare these
observational results, we constructed numerical mock LBG catalogs based on a
semianalytic model of hierarchical clustering combined with high-resolution
N-body simulation, carefully mimicking the observational selection effects. The
luminosity functions for LBGs predicted by this mock catalog were found to be
almost consistent with the observation. Moreover, the overall correlation
functions of LBGs were reproduced reasonably well. The observed dependence of
the clustering on UV luminosity was not reproduced by the model, unless
subsamples of distinct halo mass were considered. That is, LBGs belonging to
more massive dark haloes had steeper and larger-amplitude correlation
functions. With this model, we found that LBG multiplicity in massive dark
halos amplifies the clustering strength at small scales, which steepens the
slope of the correlation function. The hierarchical clustering model could
therefore be reconciled with the observed luminosity-dependence of the angular
correlation function, if there is a tight correlation between UV luminosity and
halo mass. Our finding that the slope of the correlation function depends on
luminosity could be an indication that massive dark halos hosted multiple
bright LBGs (abridged).Comment: 16 pages, 17 figures, Accepted for publication in ApJ, Full
resolution version is available at
http://zone.mtk.nao.ac.jp/~kashik/sdf/acf/sdf_lbgacf.pd
Down-Sizing in Galaxy Formation at z~1 in the Subaru/XMM-Newton Deep Survey (SXDS)
We use the deep wide-field optical imaging data of the Subaru/XMM-Newton Deep
Survey (SXDS) to discuss the luminosity (mass) dependent galaxy colours down to
z'=25.0 (5 x 10^9 h_{70}^{-2} Msun) for z~1 galaxies in colour-selected high
density regions. We find an apparent absence of galaxies on the red
colour-magnitude sequence below z'~24.2, corresponding to ~M*+2 (~10^{10} Msun)
with respect to passively evolving galaxies at z~1. Galaxies brighter than
M*-0.5 (8 x 10^{10} Msun), however, are predominantly red passively evolving
systems, with few blue star forming galaxies at these magnitudes.
This apparent age gradient, where massive galaxies are dominated by old
stellar populations while less massive galaxies have more extended star
formation histories, supports the `down-sizing' idea where the mass of galaxies
hosting star formation decreases as the Universe ages. Combined with the lack
of evolution in the shape of the stellar mass function for massive galaxies
since at least z~1, it appears that galaxy formation processes (both star
formation and mass assembly) should have occurred in an accelerated way in
massive systems in high density regions, while these processes should have been
slower in smaller systems. This result provides an interesting challenge for
modern CDM-based galaxy formation theories which predict later formation epochs
of massive systems, commonly referred to as ``bottom-up''.Comment: proof corrected version (MNRAS in press), 10 pages, 12 figures (of
which 3 are in jpg format
The Ganymede Laser Altimeter (GALA) for the Jupiter Icy Moons Explorer (JUICE): Mission, science, and instrumentation of its receiver modules
The Jupiter Icy Moons Explorer (JUICE) is a science mission led by the European Space Agency, being developed for launch in 2023. The Ganymede Laser Altimeter (GALA) is an instrument onboard JUICE, whose main scientific goals are to understand ice tectonics based on topographic data, the subsurface structure by measuring tidal response, and small-scale roughness and albedo of the surface. In addition, from the perspective of astrobiology, it is imperative to study the subsurface ocean scientifically. The development of GALA has proceeded through an international collaboration between Germany (the lead), Japan, Switzerland, and Spain. Within this framework, the Japanese team (GALA-J) is responsible for developing three receiver modules: the Backend Optics (BEO), the Focal Plane Assembly (FPA), and the Analog Electronics Module (AEM). Like the German team, GALA-J also developed software to simulate the performance of the entire GALA system (performance model). In July 2020, the Proto-Flight Models of BEO, FPA, and AEM were delivered from Japan to Germany. This paper presents an overview of JUICE/GALA and its scientific objectives and describes the instrumentation, mainly focusing on Japan’s contribution
Novel Separation Technique of Particle Reinforced Metal Matrix Composites by Fused Deposition Method
To develop a novel separation technique of matrix alloys from metal matrix composite, separation experiments for various kinds of particle reinforced metal matrix composites (PRMMCs) were carried out. The Al-4mass%Cu alloy, Al-7mass%Si alloy and cast iron were used as matrix. The SiC particles (particle size: 75μm) and Al2O3 particles (particle size: 120μm) were used as reinforcement. The PRMMC specimen was placed in a silica tube container with a small nozzle (nozzle size: 0.75mm) at the bottom and was melted by H.F. induction heating. Then the molten PRMMC specimen was forced to flow out through the nozzle by applying a certain pressure of Ar gas. Most of the molten matrix alloy flowed out through the nozzle and the remainder in the container consisted of the reinforcements and a part of the matrix alloy. The amount of separated matrix alloy increased with decreasing the volume fraction of reinforcement particles in PRMMC specimens. With decreasing the fabrication temperature from 1273K to 1073K, the amount of matrix alloy separated from SiCP/Al-7mass%Si alloy composites increased. It is considered that a reaction layer formed on the surface of SiC particles at 1273K improves the wettability between the molten matrix alloy and SiC particle, which prevents the separation of molten matrix alloy from reinforcements. On the other hand, the amount of separated matrix alloy from 20vol% Al2O3P/cast iron composites was very high due to no reaction layer formed at interface between Al2O3 particle and cast iron.THERMEC 2006: 5th International conference on processing and manufacturing of advanced materials, July 4-8, 2006, Vancouver, Canad
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