810 research outputs found
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
Production and optical properties of liquid scintillator for the JSNS experiment
The JSNS (J-PARC Sterile Neutrino Search at J-PARC Spallation Neutron
Source) experiment will search for neutrino oscillations over a 24 m short
baseline at J-PARC. The JSNS inner detector will be filled with 17 tons
of gadolinium-loaded liquid scintillator (LS) with an additional 31 tons of
unloaded LS in the intermediate -catcher and outer veto volumes.
JSNS has chosen Linear Alkyl Benzene (LAB) as an organic solvent because
of its chemical properties. The unloaded LS was produced at a refurbished
facility, originally used for scintillator production by the RENO experiment.
JSNS plans to use ISO tanks for the storage and transportation of the LS.
In this paper, we describe the LS production, and present measurements of its
optical properties and long term stability. Our measurements show that storing
the LS in ISO tanks does not result in degradation of its optical properties.Comment: 7 pages, 4 figures
A STUDY ON MULTI-MODELING FOR ARTIFACT RESTORATION
Restoration is carried out in order to restore damaged antiquities to their original form. Recently, research has been active in obtaining the target three-dimensional (3D) model by optical scanning and X-ray computed tomography (CT), as well as restoring artifacts via modeling. Because the cultural artifacts are restored in a virtual environment without direct contact with the cultural artifacts, secondary damage can be preserved. Furthermore, the restoration results can be used for the physical restoration of cultural artifacts via 3D printing. In this study, multi-digital modeling technology was used to restoration horse-shaped earthenware artifact that still had its missing part. After 3D printing, the restoration part was applied to the artifact. In order to record the shape of the artifact in detail, a high-precision 3D scanner was used to construct the shape of the artifact into a 3D model. Two models were then built as a reference for restoration: The legs of the excavated horse-shaped earthenware are believed to have been bent during burning, but they were reproduced in their entirety for restoration by conducting rigging and keyframe animation. For the restoration of the missing horse body, horse and rider-shaped vessels excavated from the same site were used as references. However, since the decorations on the reference surfaces obscured the horse body, a 3D model of the horse shape was obtained through X-ray CT segmentation modeling. Using the obtained model, the missing 3D horse body was restored. For the hind legs, the leg geometry reconstructed by the rigging was used as a reference. The hollow space inside the artifact and the structures that could be restored were further modeled. The finished model was completed by outputting a mock-up using a material extrusion system 3D printer, conducting a bonding test with actual artifacts, and finally creating the restoration model. Afterward, a photopolymerization system 3D printer is used to output the restoration part, and then it is applied to the artifacts through post-processing. A study for restoration artifacts based on multi-modeling techniques was proposed in this work. In particular, rigging and x-ray CT segmentation modeling were used to restoration the artifacts based on their original form and historical research. As such, multi-modeling techniques are an effective way to not only restore artifacts, but also to build a reference for restoration
Moduli Dynamics of AdS_3 Strings
We construct a general class of solutions for a classical string in AdS_3
spacetime. The construction is based on a Pohlmeyer type reduction, with the
sinh-Gordon model providing the general N-soliton solutions. The corresponding
exact spiky string configurations are then reconstructed through the inverse
scattering method. It is shown that the string moduli are determined entirely
by those of the solitons.Comment: 22 pages, no figures; references adde
Semiclassical strings in AdS(3) X S^2
In this paper, we investigate the semiclassical strings in AdS(3)XS^2, in
which the string configuration of AdS(3) is classified to three cases depending
on the parameters. Each of these has a different anomalous dimension
proportional to logS, S^(1/3) and S, where S is a angular momentum on AdS(3).
Further we generalize the dispersion relations for various string configuration
on AdS(3)XS^2.Comment: 15 pages, added reference
Oscillon in Einstein-scalar system with double well potential and its properties.
The dynamical evolution of self-interacting scalar field has many nontrivial behaviors, which tell us many lessons in a nonlinear dynamics. On Minkowski spacetime, the scalar field with double well potential has localized, non-singular, time-dependent, long-lived solutions, which are called oscillons. The lifetime of the oscillon depends on the initial conditions. Furthermore, when the initial parameter is fine-tuned, oscillons can be infinitely, and type I critical behavior is observed. Here, we investigate the Einstein-scalar system with double well potential. We show that oscillons exist in this system, and discuss the behavior when the initial parameter is fine-tuned. Our results suggests that a new type of critical behavior appears in this theory
Particle Probe of Horava-Lifshitz Gravity
Kehagias-Sfetsos black hole in Ho\v{r}ava-Lifshitz gravity is probed through
particle geodesics. Gravitational force of KS black hole becomes weaker than
that of Schwarzschild around horizon and interior space. Particles can be
always scattered or trapped in new closed orbits, unlike those falling forever
in Schwarzschild black. The properties of null and timelike geodesics are
classified with values of coupling constants. The precession rates of the
orbits are evaluated. The time trajectories are also classified under different
values of coupling constants for both null and timelike geodesics. Physical
phenomena that may be observable are discussed.Comment: 10 pages, 8 figure
Stability Analysis of Bulk Viscous Cosmology
In this paper, we study phase space analysis of FRW universe model by taking a power-law model for bulk viscosity coefficient. An autonomous system of equations is developed by defining normalized dimensionless variables. We find corresponding critical points for di.erent values of the parameters to investigate stability of the system. It is found that the presence of power-law model of bulk viscosity appears as an e.ective ingredient to enhance the stability of the respective universe model
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