33,098 research outputs found
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A golden block based self-refining scheme for repetitive patterned wafer inspections
This paper presents a novel technique for detecting possible defects in two-dimensional wafer images with repetitive patterns using prior knowledge. It has a learning ability that is able to create a golden block database from the wafer image itself, modify and refine its content when used in further inspections. The extracted building block is stored as a golden block for the detected pattern. When new wafer images with the same periodical pattern arrives, we do not have to re-calculate its periods and building block. A new building block can be derived directly from the existing golden block after eliminating alignment differences. If the newly derived building block has better quality than the stored golden block, then the golden block is replaced with the new building block. With the proposed algorithm, our implementation shows that a significant amount of processing time is saved. And the storage overhead of golden templates is also reduced significantly by storing golden blocks only
What Sets the Radial Locations of Warm Debris Disks?
The architectures of debris disks encode the history of planet formation in
these systems. Studies of debris disks via their spectral energy distributions
(SEDs) have found infrared excesses arising from cold dust, warm dust, or a
combination of the two. The cold outer belts of many systems have been imaged,
facilitating their study in great detail. Far less is known about the warm
components, including the origin of the dust. The regularity of the disk
temperatures indicates an underlying structure that may be linked to the water
snow line. If the dust is generated from collisions in an exo-asteroid belt,
the dust will likely trace the location of the water snow line in the
primordial protoplanetary disk where planetesimal growth was enhanced. If
instead the warm dust arises from the inward transport from a reservoir of icy
material farther out in the system, the dust location is expected to be set by
the current snow line. We analyze the SEDs of a large sample of debris disks
with warm components. We find that warm components in single-component systems
(those without detectable cold components) follow the primordial snow line
rather than the current snow line, so they likely arise from exo-asteroid
belts. While the locations of many warm components in two-component systems are
also consistent with the primordial snow line, there is more diversity among
these systems, suggesting additional effects play a role
A Comprehensive Dust Model Applied to the Resolved Beta Pictoris Debris Disk from Optical to Radio Wavelengths
We investigate whether varying the dust composition (described by the optical
constants) can solve a persistent problem in debris disk modeling--the
inability to fit the thermal emission without over-predicting the scattered
light. We model five images of the beta Pictoris disk: two in scattered light
from HST/STIS at 0.58 microns and HST/WFC3 at 1.16 microns, and three in
thermal emission from Spitzer/MIPS at 24 microns, Herschel/PACS at 70 microns,
and ALMA at 870 microns. The WFC3 and MIPS data are published here for the
first time. We focus our modeling on the outer part of this disk, consisting of
a parent body ring and a halo of small grains. First, we confirm that a model
using astronomical silicates cannot simultaneously fit the thermal and
scattered light data. Next, we use a simple, generic function for the optical
constants to show that varying the dust composition can improve the fit
substantially. Finally, we model the dust as a mixture of the most plausible
debris constituents: astronomical silicates, water ice, organic refractory
material, and vacuum. We achieve a good fit to all datasets with grains
composed predominantly of silicates and organics, while ice and vacuum are, at
most, present in small amounts. This composition is similar to one derived from
previous work on the HR 4796A disk. Our model also fits the thermal SED,
scattered light colors, and high-resolution mid-IR data from T-ReCS for this
disk. Additionally, we show that sub-blowout grains are a necessary component
of the halo.Comment: 23 pages, 20 figures, accepted to Ap
Aharonov-Casher phase and persistent current in a polyacetylene ring
We investigate a polyacetylene ring in an axially symmetric, static electric
field with a modified SSH Hamiltonian of a polyacetylene chain. An effective
gauge potential of the single electron Hamiltonian due to spin-field
interaction is obtained and it results in a Fr\"{o}hlich's type of
superconductivity equivalent to the effect of travelling lattice wave. The
total energy as well as the persistent current density are shown to be a
periodic function of the flux of the gauge field embraced by the polyacetylene
ring.Comment: 12 pages, 5 figure
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Dynamic Behavior of Precast Concrete Beam-Column Sub-Assemblages with High Performance Connections Subjected to Sudden Column Removal Scenario
Unbonded posttensioned precast concrete (UPPC) structure has shown its excellent aseismic performance in laboratory tests and earthquake investigation. However, the progressive collapse behavior of UPPC subjected to column removal scenario is still unclear. To fill this knowledge gap, two 1/2 scaled UPPC beam-column sub-assemblages were tested under a penultimate column removal scenario. The dynamic test results indicated that UPPC sub-assemblages have desirable load redistribution capacity to mitigate progressive collapse. The failure modes of the sub-assemblages observed in dynamic test were quite similar to that in static counterparts
A conditional quantum phase gate between two 3-state atoms
We propose a scheme for conditional quantum logic between two 3-state atoms
that share a quantum data-bus such as a single mode optical field in cavity QED
systems, or a collective vibrational state of trapped ions. Making use of
quantum interference, our scheme achieves successful conditional phase
evolution without any real transitions of atomic internal states or populating
the quantum data-bus. In addition, it only requires common addressing of the
two atoms by external laser fields.Comment: 8 fig
Mott-Peierls Transition in the extended Peierls-Hubbard model
The one-dimensional extended Peierls-Hubbard model is studied at several band
fillings using the density matrix renormalization group method. Results show
that the ground state evolves from a Mott-Peierls insulator with a correlation
gap at half-filling to a soliton lattice with a small band gap away from
half-filling. It is also confirmed that the ground state of the Peierls-Hubbard
model undergoes a transition to a metallic state at finite doping. These
results show that electronic correlations effects should be taken into account
in theoretical studies of doped polyacetylene. They also show that a
Mott-Peierls theory could explain the insulator-metal transition observed in
this material.Comment: 4 pages with 3 embedded eps figure
Submillimeter Array multiline observations of the massive star-forming region IRAS 18089-1732
Submillimeter Array (SMA) observations of the high-mass star-forming region
IRAS 18089-1732 in the 1 mm and 850 m band with 1 GHz bandwidth reveal a
wealth of information. We present the observations of 34 lines from 16
different molecular species. Most molecular line maps show significant
contributions from the outflow, and only few molecules are confined to the
inner core. We present and discuss the molecular line observations and outline
the unique capabilities of the SMA for future imaging line surveys at high
spatial resolution.Comment: Accepted for ApJ Letters, SMA special volum
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