7,576 research outputs found
Recommended from our members
Effect of Post-Processing on the Microstructure and Mechanical Properties of Ultra-Low Carbon Steel Fabricated by Selective Laser Melting
In this study, the effects of heat treatments and hot-isotactic pressing (HIP) on the
microstructure and mechanical properties of ultra-low carbon steel produced using selective laser
melting (SLM) were investigated. Powder and prototypes characterizations including XRD phase
analysis, microstructural observations, and hardness were performed. It was found that heat
treatments at 1000 ÂșC and HIP process improved inter-particle bonding very slightly. Significant
increases in the grain size were observed for the annealed specimens at 600ÂșC and above as well
as after HIP due to recrystallization and further grain growth, which coincide with the drop in
hardness.Mechanical Engineerin
Spontaneous magnetization of the XXZ Heisenberg spin-1/2 chain
Determinant representations of form factors are used to represent the
spontaneous magnetization of the Heisenberg XXZ chain (Delta >1) on the finite
lattice as the ratio of two determinants. In the thermodynamic limit (the
lattice of infinite length), the Baxter formula is reproduced in the framework
of Algebraic Bethe Ansatz. It is shown that the finite size corrections to the
Baxter formula are exponentially small.Comment: 18 pages, Latex2
Quantum escape of the phase in a strongly driven Josephson junction
A quantum mechanical analysis of the Josephson phase escape in the presence
of both dc and ac bias currents is presented. We find that the potential
barrier for the escape of the phase is effectively suppressed as the resonant
condition occurs, i.e. when the frequency of the ac bias matches the
Josephson junction energy level separation. This effect manifests itself by a
pronounced drop in the dependence of the switching current on the power
of the applied microwave radiation and by a peculiar double-peak structure
in the switching current distribution . The developed theory is in a
good accord with an experiment which we also report in this paper. The obtained
features can be used to characterize certain aspects of the quantum-mechanical
behavior of the Josephson phase, such as the energy level quantization, the
Rabi frequency of coherent oscillations and the effect of damping.Comment: 4 pages, 3 figures, to be published in Physical Review B (Rapid
Communication
Recommended from our members
Effect of Scanning Methods in the Selective Laser Melting of 316L/TiC Nanocomposites
Selective laser melting (SLM) is a promising additive manufacturing process that allows
for the fabrication of complex functional components by the selective layer-by-layer melting of
particles on a powder bed using a high-energy laser beam. In this study, the SLM process was
used to fabricate components of TiC/ 316L stainless steel nanocomposite using various laser
scanning methods. The results showed that the laser-scanning method used for the SLM process
affects the degree of densification, microstructure, and the hardness of the components produced.
We believe that the alternative fabrication route presented in this study should significantly
increase the use of nanocomposites.Mechanical Engineerin
Anomalous Roughening in Experiments of Interfaces in Hele-Shaw Flows with Strong Quenched Disorder
We report experimental evidences of anomalous kinetic roughening in the
stable displacement of an oil-air interface in a Hele-Shaw cell with strong
quenched disorder. The disorder consists on a random modulation of the gap
spacing transverse to the growth direction (tracks). We have performed
experiments varying average interface velocity and gap spacing, and measured
the scaling exponents. We have obtained beta=0.50, beta*=0.25, alpha=1.0,
alpha_l=0.5, and z=2. When there is no fluid injection, the interface is driven
solely by capillary forces, and a higher value of beta around beta=0.65 is
measured. The presence of multiscaling and the particular morphology of the
interfaces, characterized by high slopes that follow a L\'evy distribution,
confirms the existence of anomalous scaling. From a detailed study of the
motion of the oil--air interface we show that the anomaly is a consequence of
different local velocities over tracks plus the coupling in the motion between
neighboring tracks. The anomaly disappears at high interface velocities, weak
capillary forces, or when the disorder is not sufficiently persistent in the
growth direction. We have also observed the absence of scaling when the
disorder is very strong or when a regular modulation of the gap spacing is
introduced.Comment: 14 pages, 17 figure
Dark Matter Constraints on Gaugino/Higgsino Masses in Split Supersymmetry and Their Implications at Colliders
In split supersymmetry, gauginos and Higgsinos are the only supersymmetric
particles which are possibly accessible at foreseeable colliders. While the
direct experimental searches, such as LEP and Tevatron experiments, gave robust
lower bounds on the masses of these particles, the cosmic dark matter can give
some upper bounds and thus have important implications for the searches at
future colliders. In this work we scrutinize such dark matter constraints and
show the allowed mass range for charginos and neutralinos (the mass eigenstates
of gauginos and Higgsinos). We find that the lightest chargino must be lighter
than about 1 TeV under the popular assumption M_1=M_2/2 and about 2 or 3 TeV in
other cases. The corresponding production rates of the lightest chargino at the
CERN Large Hadron Collider (LHC) and the International Linear Colldier (ILC)
are also shown. While in some parts of the allowed region the chargino pair
production rate can be larger than 1 pb at LHC and 100 fb at the ILC, other
parts of the region correspond to very small production rates and thus there is
no guarantee to find the charginos of split supersymmetry at future colliders.Comment: version in EPJC (refs added
Comments on Baryon Melting in Quark Gluon Plasma with Gluon Condensation
We consider a black hole solution with a non-trivial dilaton from IIB super
gravity which is expected to describe a strongly coupled hot gauge plasma with
non-vanishing gluon condensation present. We construct a rotating and moving
baryon to probe the screening and phases of the plasma. Melting of the baryons
in hot plasma in this background had been studied previously, however, we show
that baryons melt much lower temperature than has been suggested previously.Comment: 3 figures, 12 page
Submergence of the Sidebands in the Photon-assisted Tunneling through a Quantum Dot Weakly Coupled to Luttinger Liquid Leads
We study theoretically the photon-assisted tunneling through a quantum dot
weakly coupled to Luttinger liquids (LL) leads, and find that the zero bias dc
conductance is strongly affected by the interactions in the LL leads. In
comparison with the system with Fermi liquid (FL) leads, the sideband peaks of
the dc conductance become blurring for 1/2<g<1, and finally merge into the
central peak for g<1/2, (g is the interaction parameter in the LL leads). The
sidebands are suppressed for LL leads with Coulomb interactions strong enough,
and the conductance always appears as a single peak for any strength and
frequency of the external time-dependent field. Furthermore, the quenching
effect of the central peak for the FL case does not exist for g<1/2.Comment: 9 pages, 4 figure
Correlation functions of the XXZ spin-1/2 Heisenberg chain at the free fermion point from their multiple integral representations
Using multiple integral representations, we derive exact expressions for the
correlation functions of the spin-1/2 Heisenberg chain at the free fermion
point.Comment: 24 pages, LaTe
- âŠ