2,198 research outputs found
Effect of Relative Humidity on Mechanical Degradation of Medium Mn Steels
Medium Mn steels have been considered as the next-generation materials for use in the automotive industry due to their excellent strength and ductility balance. To reduce the total weight and improve the safety of vehicles, medium Mn steels look forward to a highly promising future. However, hydrogen-induced delayed cracking is a concern for the use of high strength steels. This work is focused on the service characteristics of two kinds of medium Mn steels under different relative humidity conditions (40%, 60%, 80% and 100%). Under normal relative humidity (about 40%) at 25 °C, the hydrogen concentration in steel is 0.4 ppm. When exposed to higher relative humidity, the hydrogen concentration in steel increases slowly and reaches a stable value, about 0.8 ppm. In slow strain rate tensile tests under different relative humidity conditions, the tensile strength changed, the hydrogen concentration increased and the elongation decreased as well, thereby increasing the hydrogen embrittlement sensitivity. In other words, the smaller the tensile rate applied, the greater the hydrogen embrittlement sensitivity. In constant load tests under different relative humidity conditions, the threshold value of the delayed cracking of M7B (‘M’ referring to Mn, ‘7’ meaning the content of Mn, ‘B’ denoting batch annealing) steel maintains a steady value of 0.82 σb (tensile strength). The threshold value of the delayed cracking of M10B significantly changed along with relative humidity. When relative humidity increased from 60% to 80%, the threshold dropped sharply from 0.63 σb to 0.52 σb. We define 80% relative humidity as the ‘threshold humidity’ for M10B
Consistency of shared reference frames should be reexamined
In a recent Letter [G. Chiribella et al., Phys. Rev. Lett. 98, 120501
(2007)], four protocols were proposed to secretly transmit a reference frame.
Here We point out that in these protocols an eavesdropper can change the
transmitted reference frame without being detected, which means the consistency
of the shared reference frames should be reexamined. The way to check the above
consistency is discussed. It is shown that this problem is quite different from
that in previous protocols of quantum cryptography.Comment: 3 pages, 1 figure, comments are welcom
Multi-spectral image change detection based on single-band iterative weighting and fuzzy C-means clustering
Association of LEP G2548A and LEPR Q223R Polymorphisms with Cancer Susceptibility: Evidence from a Meta-Analysis
__Background:__ Numerous epidemiological studies have examined associations of genetic variations in LEP (G2548A, -2548 nucleotide upstream of the ATG start site) and LEPR (Q223R, nonsynonymous SNP in exon 6) with cancer susceptibility; however, the findings are inconsistent. Therefore, we performed a meta-analysis to comprehensively evaluate such associations.
__Methods:__ We searched published literature from MEDLINE, EMBASE, Web of Science and CBM for eligible publications. We also assessed genotype-based mRNA expression data from HapMap for rs7799039 (G2548A) and rs1137101 (Q223R) in normal cell lines derived from 270 subjects with different ethnicities.
__Results:__ The final analysis included 16 published studies of 6569 cases and 8405 controls for the LEP G2548A and 19 studies of 7504 cases and 9581 controls for the LEPR Q223R. Overall, LEP G2548A was statistically significantly associated with an increased risk of overall cancer (AA vs. GG: OR=1.27, 95% CI=1.05-1.54; recessive model: OR=1.19, 9
Gluon fragmentation to ^3D_J quarkonia
We present a calculation of the leading order QCD fragmentation functions for
gluons to split into spin-triplet D-wave quarkonia. We apply them to evaluate
the gluon fragmentation contributions to inclusive ^3D_J quarkonium production
at large transverse momentum processes like the Tevatron and find that the
D-wave quarkonia, especially the charmonium 2^{--} state, could be observed
through color-octet mechanism with present luminosity. Since there are
distinctively large gaps between the contributions of two different (i.e,
color-singlet and color-octet) quarkonium production mechanisms, our results
may stand as a unique test to NRQCD color-octet quarkonium production
mechanism.Comment: 15 pages in LaTex (2 figures in PS-file
Development of high-precision distributed wireless microseismic acquisition stations
In recent years, owing to the shortage of oil and gas resources
and increasing difficulty in mining, traditional (wired) microseismic
monitoring equipment has been unable to meet the needs of energy
exploitation. Therefore, it is necessary to develop new high-precision
seismic exploration and data acquisition systems. In this study, we combined
advanced acquisition systems with wireless technology to develop a new
wireless microseismic acquisition system. The hardware circuit of the
acquisition system mainly includes a data acquisition board and a main
control board. High-precision analog-to-digital conversion and digital
filtering technologies are used to provide data with high signal-to-noise
ratios, resolution, and fidelity to the acquisition stations. Key
technologies were integrated into the ARM (Advanced RISC Machines)
of the main control board: reliable
GPS technology was employed to realize synchronous acquisitions among various
acquisition stations, and WIFI technology was used to achieve wireless data
communication between acquisition stations and the central station, thus
improving the data transmission speed and accuracy. After conducting a series
of evaluation tests, it was found that the system was stable, convenient to
use, and had high data accuracy, therefore providing significant support for
the solution to problems encountered in current oil and gas exploration
processes, such as the complicated environment and inconvenient construction.</p
Strong and weak pulsar radio emission due to thunderstorms and raindrops of particles in the magnetosphere
Pulsars radiate radio signals when they rotate. However, some old pulsars
often stop radiating for some periods. The underlying mechanism remains
unknown, while the magnetosphere during nulling phases is hard to probe due to
the absence of emission measurement. Here we report the detection and accurate
polarization measurements of sporadic weak narrow dwarf pulses detected in the
ordinary nulling state of pulsar B2111+46 via the Five-Hundred-Meter Aperture
Spherical radio Telescope (FAST). Further analysis shows that their
polarization angles follow the average polarization angle curve of normal
pulses, suggesting no change of magnetic field structure in the emission region
in the two emission states. Whereas radio emission of normal individual pulses
is radiated by a thunderstorm of particles produced by copious discharges in
regularly formed gaps, dwarf pulses are produced by one or a few raindrops of
particles generated by pair production in a fragile gap of this near-death
pulsar.Comment: 37 pages, 15 figures. Authors version. Great FAST pulsar data. Share
full-text access: https://rdcu.be/djLS
Structural and Luminescence Properties of Silica-Based Hybrids Containing New Silylated-Diketonato Europium(III) Complex
A new betadiketonate ligand displaying a trimethoxysilyl group as grafting function and a diketone moiety as complexing site (TTA-Si = 4,4,4-trifluoro-2-(3-trimethoxysilyl)propyl)-1-3-butanedione (C4H3S)COCH[(CH2)3Si(OCH3)3]COCF3) and its highly luminescent europium(III) complex [Eu(TTA-Si)3] have been synthesized and fully characterized. Luminescent silica-based hybrids have been prepared as well with this new complex grafted on the surface of dense silica nanoparticles (28 (+/-3 nm) or on mesoporous
silica particles. The covalent bonding of Eu(TTA-Si)3 inside the core of uniform silica
nanoparticles (40 (+/- 5 nm) was also achieved. Luminescence properties are discussed in relation to the europium chemical environment involved in each of the three hybrids. The general methodology proposed allowed high grafting ratios and overcame chelate release and tendency to agglomeration, and it could be applied to any silica matrix (in the core or at the surface, nanosized or not, dense or mesoporous) and therefore numerous applications such as luminescent markers and luminophors could be foreseen
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