3,864 research outputs found
Dramatic improvement of strain hardening and ductility to 95% in highly-deformable high-strength duplex lightweight steels
Ferrite + austenite duplex lightweight steels have been actively developed by adding low-density Al for overcoming a limitation of stiffness deterioration by a traditional approach to obtain a weight reduction. Multiple-stage deformation mechanism in lightweight steels, i.e., simultaneous formation of deformation-induced martensite and deformation twin and additional plasticity by twinning, has been nominated as an attractive strategy, but shows a steady flow behavior with early plastic instability. Here, we present a newly designed Fe-0.3C-9Mn-5Al steel in order to obtain an optimal level of stability of austenite and a resultant outstanding combination of tensile strength and ductility, e.g., 874 MPa and 72%, together with sufficiently high strain hardening. These enhanced properties are attributed to the decreased austenite stability by controlling the austenite size and alloying partitioning due to variation in austenite fraction inside duplex microstructures. The present work gives a promise for structural applications requiring both reduced specific weight and remarkable deformability. ? 2017 The Author(s).114Ysciescopu
Static Potential in N=4 Supersymmetric Yang-Mills Theory
We compute the leading order perturbative correction to the static potential
in supersymmetric Yang-Mills theory. We show that the perturbative
expansion contains infrared logarithms which, when resummed, become logarithms
of the coupling constant. The resulting correction goes in the right direction
to match the strong coupling behavior obtained from the AdS/CFT correspondence.
We find that the strong coupling extrapolation of the sum of ladder diagrams
goes as , as in the supergravity approach.Comment: 8 pages, four figures using feynm
Geodesic motions in extraordinary string geometry
The geodesic properties of the extraordinary vacuum string solution in (4+1)
dimensions are analyzed by using Hamilton-Jacobi method. The geodesic motions
show distinct properties from those of the static one. Especially, any freely
falling particle can not arrive at the horizon or singularity. There exist
stable null circular orbits and bouncing timelike and null geodesics. To get
into the horizon {or singularity}, a particle need to follow a non-geodesic
trajectory. We also analyze the orbit precession to show that the precession
angle has distinct features for each geometry such as naked singularity, black
string, and wormhole.Comment: 15 pages, 11 figure
Role of dietary concentrates on the venison quality of Sika deer (Cervus nippon)
The aim of this study was to evaluate the effect of feed concentrate level on carcass characteristics and meat quality of sika deer (Cervus nippon). A total of 16 sika deer (mean bodyweight 30 kg) were randomly assigned to one of two treatments, namely Treatment 1 (T1): fed concentrate at 1.5% of total bodyweight); and Treatment 2 (T2): fed concentrate ad libitum. Both groups had free access to roughage (hay) and water. Each group was fed concentrate twice daily (at 09h00 and 16h00) for eight months. The fat concentration of venison from deer in T2 was significantly greater than that of T1. However, fat loss through cooking, shear force, and pH did not differ significantly between the two groups. Water-binding capacity of venison from deer in T1 was significantly greater (2.83%) than that of T2. Colour parameters a* (redness) and b* (yellowness) were significantly greater for venison from T2 than for deer in T1. Likewise, cholesterol concentration of venison from deer in T2 was significantly greater than for deer in T1. However, the cholesterol concentration in venison from deer that were subjected to both treatments was less than that of meat from other livestock species. In conclusion, the results of this study provide a baseline to estimate fodder cost standards to produce sika deer venison, and would aid commercial deer farmers in developing optimal management strategies for venison production.Keywords: carcass composition, concentrate feeding, meat qualit
Greybody Factors of Charged Dilaton Black Holes in 2 + 1 Dimensions
We have studied scalar perturbations of charged dilaton black holes in 2+1
dimensions. The black hole considered here is a solution to the low-energy
string theory in 2+1 dimensions. The exact decay rates and the grey body
factors for the massless minimally coupled scalar is computed for both the
charged and the uncharged dilaton black holes. The charged and the uncharged
black hole show similar behavior for grey body factors, reflection coefficients
and decay rates.Comment: The equation for the potential and figure:1 are changed. The changes
does not effect the result
Assessment of Current Jet Noise Prediction Capabilities
An assessment was made of the capability of jet noise prediction codes over a broad range of jet flows, with the objective of quantifying current capabilities and identifying areas requiring future research investment. Three separate codes in NASA s possession, representative of two classes of jet noise prediction codes, were evaluated, one empirical and two statistical. The empirical code is the Stone Jet Noise Module (ST2JET) contained within the ANOPP aircraft noise prediction code. It is well documented, and represents the state of the art in semi-empirical acoustic prediction codes where virtual sources are attributed to various aspects of noise generation in each jet. These sources, in combination, predict the spectral directivity of a jet plume. A total of 258 jet noise cases were examined on the ST2JET code, each run requiring only fractions of a second to complete. Two statistical jet noise prediction codes were also evaluated, JeNo v1, and Jet3D. Fewer cases were run for the statistical prediction methods because they require substantially more resources, typically a Reynolds-Averaged Navier-Stokes solution of the jet, volume integration of the source statistical models over the entire plume, and a numerical solution of the governing propagation equation within the jet. In the evaluation process, substantial justification of experimental datasets used in the evaluations was made. In the end, none of the current codes can predict jet noise within experimental uncertainty. The empirical code came within 2dB on a 1/3 octave spectral basis for a wide range of flows. The statistical code Jet3D was within experimental uncertainty at broadside angles for hot supersonic jets, but errors in peak frequency and amplitude put it out of experimental uncertainty at cooler, lower speed conditions. Jet3D did not predict changes in directivity in the downstream angles. The statistical code JeNo,v1 was within experimental uncertainty predicting noise from cold subsonic jets at all angles, but did not predict changes with heating of the jet and did not account for directivity changes at supersonic conditions. Shortcomings addressed here give direction for future work relevant to the statistical-based prediction methods. A full report will be released as a chapter in a NASA publication assessing the state of the art in aircraft noise prediction
Scattering from an AdS_3 bubble and an exact AdS_3
We investigate the close relationship between the potential and absorption
cross section for test fields in an AdS bubble(a 5D black hole) and an
exact AdS. There are two solutions in type IIB string theory: an AdS
bubble corresponds to the dilatonic solution, while an exact AdS is the
non-dilatonic solution. In order to obtain the cross section for an AdS
bubble, we introduce the \{out\}-state scattering picture with the AdS-AFS
matching procedure. For an exact AdS, one considers the \{in\}-state
scattering picture with the AdS-AdS matching. Here the non-normalizable
modes are crucially taken into account for the matching procedure. It turns out
that the cross sections for the test fields in an AdS bubble take the same
forms as those in an exact AdS. This suggests that in the dilute gas and
the low energy limits, the S-matrix for an AdS bubble can be derived from
an exact AdS space.Comment: revised version to appear in Physical Review D, 26 pages with
embedded 5 EPS figures in RevTex forma
Non-renormalization of next-to-extremal correlators in N=4 SYM and the AdS/CFT correspondence
We show that next-to-extremal correlators of chiral primary operators in N=4
SYM theory do not receive quantum corrections to first order in perturbation
theory. Furthermore we consider next-to-extremal correlators within AdS
supergravity. Here the exchange diagrams contributing to these correlators
yield results of the same free-field form as obtained within field theory. This
suggests that quantum corrections vanish at strong coupling as well.Comment: 21 pages, LaTex, 9 eps figures, typos corrected and references adde
Photoemission and x-ray absorption study of MgC_(1-x)Ni_3
We investigated electronic structure of MgC_(1-x)Ni_3 with photoemission and
x-ray absorption spectroscopy. Both results show that overall band structure is
in reasonable agreement with band structure calculations including the
existence of von Hove singularity (vHs)near E_F. However, we find that the
sharp vHs peak theoretically predicted near the E_F is substantially
suppressed. As for the Ni core level and absorption spectrum, there exist the
satellites of Ni 2p which have a little larger energy separation and reduced
intensity compared to the case of Ni-metal. These facts indicate that
correlation effects among Ni 3d electrons may be important to understand
various physical properties.Comment: 12 pages, 4 figure
The holographic superconductors in higher-dimensional AdS soliton
We explore the behaviors of the holographic superconductors at zero
temperature for a charged scalar field coupled to a Maxwell field in
higher-dimensional AdS soliton spacetime via analytical way. In the probe
limit, we obtain the critical chemical potentials increase linearly as a total
dimension grows up. We find that the critical exponent for condensation
operator is obtained as 1/2 independently of , and the charge density is
linearly related to the chemical potential near the critical point.
Furthermore, we consider a slightly generalized setup the
Einstein-Power-Maxwell field theory, and find that the critical exponent for
condensation operator is given as in terms of a power parameter
of the Power-Maxwell field, and the charge density is proportional to the
chemical potential to the power of .Comment: LaTeX, 16 pages, 5 figures, typos corrected, one reference added,
version to appear in European Physical Journal
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