662 research outputs found
Strain-Induced Precipitation Kinetics of Vanadium Carbonitride Precipitates with the Cubic Structure in High-Strength Weathering Steels
The strain-induced precipitation kinetic model of vanadium carbonitride [V(C, N)] precipitates with the cubic structure in vanadium-nitrogen (V–N) microalloyed high-strength weathering steels was constructed and validated.Построена кинетическая модель деформационного осаждения фаз карбонитрида ванадия (V(C, N)) кубической структуры в микролегированных высокопрочных сталях, стойких к атмосферной коррозии, и проверена ее достоверность
Ratcheting effect of reinforced graphite sheet with stainless steel insert (RGSWSSI) under cyclic compression at elevated temperature
Ratcheting and creep of RGSWSSI are tested under cyclic stress-controlled compression by a self-designed clamp from 500ºC to 600ºC. The effects of insert type, temperature, stress amplitude, stress rate, creep and loading sequence are considered. Results present that ratcheting deformations for RGSWSSI with 316L stainless steel tanged and bonded insert approach to each other and show little rate-dependence, while they slightly increase with the increment of stress amplitude and temperature. Moreover, obvious ratcheting effect takes place under cyclic pulsating loads with the peak stress of 32MPa at 500ºC or higher. The accumulated deformations of RGSWSSI under small stress amplitude only increase during about the first 25 cycles, and then always turn to shakedown. It can also be estimated by the corresponding static creep strain in practical engineering with good accuracy at high temperature. This work provides important data and understanding of RGSWSSI under harsh fluctuating loads
Study on the Cracking Mechanism of YQ450NQR1 High-Strength Weathering Steel
YQ450NQR1 high-strength weathering steel is prone to cracking. The cracking patterns and morphology were detected by metallographic and scanning electron microscopies. The decarburized layer around the cracks is indicative of their origination in the continuous casting bloom. Then, the controlling factors were established by analyzing the carbon content of molten steel, residual elements in the alloy, purity and performance of the mold powder, and secondary cooling water flow of the mold. Results show that the process optimization reduced the cracking reject ratio from 3.5 to 0.78%.Высокопрочная сталь YQ450NQR1, стойкая к атмосферной коррозии, проявляет склонность к образованию трещин. Исследованы характер трещинообразования и морфология с помощью металлографической и сканирующей электронной микроскопии. Образование обезуглероженного слоя вокруг трещин свидетельствует об их зарождении в непрерывной литой заготовке. Установлены регулирующие факторы путем анализа содержания углерода в расплавленной стали, остаточных элементов в сплаве, чистоты и эффективности пресс-порошка, расхода воды вторичного охлаждения формы. Показано, что оптимазация процесса снизила уровень отбраковки материала, содержащего трещины, с 3,50 до 0,78%
Effect of an Electron-phonon Interaction on the One-electron Spectral Weight of a d-wave Superconductor
We analyze the effects of an electron-phonon interaction on the one-electron
spectral weight A(k,omega) of a d_{x^2-y^2} superconductor. We study the case
of an Einstein phonon mode with various momentum-dependent electron-phonon
couplings and compare the structure produced in A(k,omega) with that obtained
from coupling to the magnetic pi-resonant mode. We find that if the strength of
the interactions are adjusted to give the same renormalization at the nodal
point, the differences in A(k,omega) are generally small but possibly
observable near k=(pi,0).Comment: 10 pages, 14 figures (color versions of Figs. 2,4,10,11,12 available
upon request
Mass-renormalized electronic excitations at (, 0) in the superconducting state of
Using high-resolution angle-resolved photoemission spectroscopy on
, we have made the first observation of a
mass renormalization or "kink" in the E vs. dispersion relation
localized near . Compared to the kink observed along the nodal
direction, this new effect is clearly stronger, appears at a lower energy near
40 meV, and is only present in the superconducting state. The kink energy scale
defines a cutoff below which well-defined quasiparticle excitations occur. This
effect is likely due to coupling to a bosonic excitation, with the most
plausible candidate being the magnetic resonance mode observed in inelastic
neutron scattering
Magnetic Properties of YBa_2Cu_3O_{7-\delta} in a self-consistent approach: Comparison with Quantum-Monte-Carlo Simulations and Experiments
We analyze single-particle electronic and two-particle magnetic properties of
the Hubbard model in the underdoped and optimally-doped regime of \YBCO by
means of a modified version of the fluctuation-exchange approximation, which
only includes particle-hole fluctuations. Comparison of our results with
Quantum-Monte Carlo (QMC) calculations at relatively high temperatures () suggests to introduce a temperature renormalization in order to
improve the agreement between the two methods at intermediate and large values
of the interaction .
We evaluate the temperature dependence of the spin-lattice relaxation time
and of the spin-echo decay time and compare it with the results
of NMR measurements on an underdoped and an optimally doped \YBCO sample. For
it is possible to consistently adjust the parameters of the Hubbard
model in order to have a good {\it semi-quantitative} description of this
temperature dependence for temperatures larger than the spin gap as obtained
from NMR measurements. We also discuss the case , which is more
appropriate to describe magnetic and single-particle properties close to
half-filling. However, for this larger value of the agreement with QMC as
well as with experiments at finite doping is less satisfactory.Comment: Final version, to appear in Phys. Rev. B (sched. Feb. 99
Electron Dynamics in NdCeCuO: Evidence for the Pseudogap State and Unconventional c-axis Response
Infrared reflectance measurements were made with light polarized along the a-
and c-axis of both superconducting and antiferromagnetic phases of electron
doped NdCeCuO. The results are compared to
characteristic features of the electromagnetic response in hole doped cuprates.
Within the CuO planes the frequency dependent scattering rate,
1/, is depressed below 650 cm; this behavior is a
hallmark of the pseudogap state. While in several hole doped compounds the
energy scales associated with the pseudogap and superconducting states are
quite close, we are able to show that in NdCeCuO
the two scales differ by more than one order of magnitude. Another feature of
the in-plane charge response is a peak in the real part of the conductivity,
, at 50-110 cm which is in sharp contrast with the
Drude-like response where is centered at . This
latter effect is similar to what is found in disordered hole doped cuprates and
is discussed in the context of carrier localization. Examination of the c-axis
conductivity gives evidence for an anomalously broad frequency range from which
the interlayer superfluid is accumulated. Compelling evidence for the pseudogap
state as well as other characteristics of the charge dynamics in
NdCeCuO signal global similarities of the cuprate
phase diagram with respect to electron and hole doping.Comment: Submitted to PR
A Computational Study of Three Frequent Mutations of EGFR and their Effects on Protein Dimer Formation and Non-Small Cell Lung Cancer Drug Resistance
Partial Wave Analysis of
BES data on are presented. The
contribution peaks strongly near threshold. It is fitted with a
broad resonance with mass MeV, width MeV. A broad resonance peaking at 2020 MeV is also required
with width MeV. There is further evidence for a component
peaking at 2.55 GeV. The non- contribution is close to phase
space; it peaks at 2.6 GeV and is very different from .Comment: 15 pages, 6 figures, 1 table, Submitted to PL
Partial wave analysis of J/\psi \to \gamma \phi \phi
Using events collected in the BESII detector, the
radiative decay is
studied. The invariant mass distribution exhibits a near-threshold
enhancement that peaks around 2.24 GeV/.
A partial wave analysis shows that the structure is dominated by a
state () with a mass of
GeV/ and a width of GeV/. The
product branching fraction is: .Comment: 11 pages, 4 figures. corrected proof for journa
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