37,762 research outputs found
Detection of dirt impairments from archived film sequences : survey and evaluations
Film dirt is the most commonly encountered artifact in archive restoration applications. Since dirt usually appears as a temporally impulsive event, motion-compensated interframe processing is widely applied for its detection. However, motion-compensated prediction requires a high degree of complexity and can be unreliable when motion estimation fails. Consequently, many techniques using spatial or spatiotemporal filtering without motion were also been proposed as alternatives. A comprehensive survey and evaluation of existing methods is presented, in which both qualitative and quantitative performances are compared in terms of accuracy, robustness, and complexity. After analyzing these algorithms and identifying their limitations, we conclude with guidance in choosing from these algorithms and promising directions for future research
Segmentation-assisted detection of dirt impairments in archived film sequences
A novel segmentation-assisted method for film dirt detection is proposed. We exploit the fact that film dirt manifests in the spatial domain as a cluster of connected pixels whose intensity differs substantially from that of its neighborhood and we employ a segmentation-based approach to identify this type of structure. A key feature of our approach is the computation of a measure of confidence attached to detected dirt regions which can be utilized for performance fine tuning. Another important feature of our algorithm is the avoidance of the computational complexity associated with motion estimation. Our experimental framework benefits from the availability of manually derived as well as objective ground truth data obtained using infrared scanning. Our results demonstrate that the proposed method compares favorably with standard spatial, temporal and multistage median filtering approaches and provides efficient and robust detection for a wide variety of test material
Universal Ratios of Characteristic Lengths in Semidilute Polymer Solutions
We use experimental and simulation data from the literature to infer five
characteristic lengths, denoted , , , , and
of a semidilute polymer solution. The first two of these are defined in
terms of scattering from the solution, the third is defined in terms of osmotic
pressure, the fourth by the spatial monomer concentration profile, and the last
by co-operative diffusion. In a given solution the ratios of any of these five
lengths are expected to be universal constants. Knowing these constants thus
allows one to use one measured property of a solution as a means of inferring
others. We calculate these ratios and estimate their uncertainties for
solutions in theta as well as good-solvent conditions. The analysis is
strengthened by use of scattering properties of isolated polymers inferred from
computer simulations.Comment: 15 pages(pdf), to be submitted to Macromolecules or J. Chem. Phy
Dark matter cores and cusps in spiral galaxies and their explanations
We compare proposed solutions to the core vs cusp issue of spiral galaxies, which has also been framed as a diversity problem, and demonstrate that the cuspiness of dark matter halos is correlated with the stellar surface brightness. We compare the rotation curve fits to the SPARC sample from a self-interacting dark matter (SIDM) model, which self-consistently includes the impact of baryons on the halo profile, and hydrodynamical N-body simulations with cold dark matter (CDM). The SIDM model predicts a strong correlation between the core size and the stellar surface density, and it provides the best global fit to the data. The CDM simulations without strong baryonic feedback effects fail to explain the large dark matter cores seen in low surface brightness galaxies. On the other hand, with strong feedback, CDM simulations do not produce galaxy analogs with high stellar and dark matter densities, and therefore they have trouble in explaining the rotation curves of high surface brightness galaxies. This implies that current feedback implementations need to be modified. We also explicitly show how the concentration-mass and stellar-to-halo mass relations together lead to a radial acceleration relation (RAR) in an averaged sense, and reiterate the point that the RAR does not capture the diversity of galaxy rotation curves in the inner regions. These results make a strong case for SIDM as the explanation for the cores and cusps of field galaxies
Spinons and helimagnons in the frustrated Heisenberg chain
We investigate the dynamical spin structure factor S(q,w) for the Heisenberg
chain with ferromagnetic nearest (J1<0) and antiferromagnetic next-nearest
(J2>0) neighbor exchange using bosonization and a time-dependent density-matrix
renormalization group algorithm. For |J1|<< J2 and low energies we analytically
find and numerically confirm two spinon branches with different velocities and
different spectral weights. Following the evolution of S(q,w) with decreasing
J1/J2 we find that helimagnons develop at high energies just before entering
the ferromagnetic phase. Furthermore, we show that a recent interpretation of
neutron scattering data for LiCuVO4 in terms of two weakly coupled
antiferromagnetic chains (|J_1|<< J2) is not viable. We demonstrate that the
data are instead fully consistent with a dominant ferromagnetic coupling, J1/J2
~ -2.Comment: 5 pages, 3 figure
Static, massive fields and vacuum polarization potential in Rindler space
In Rindler space, we determine in terms of special functions the expression
of the static, massive scalar or vector field generated by a point source. We
find also an explicit integral expression of the induced electrostatic
potential resulting from the vacuum polarization due to an electric charge at
rest in the Rindler coordinates. For a weak acceleration, we give then an
approximate expression in the Fermi coordinates associated with the uniformly
accelerated observer.Comment: 11 pages, latex, no figure
Expert system training and control based on the fuzzy relation matrix
Fuzzy knowledge, that for which the terms of reference are not crisp but overlapped, seems to characterize human expertise. This can be shown from the fact that an experienced human operator can control some complex plants better than a computer can. Proposed here is fuzzy theory to build a fuzzy expert relation matrix (FERM) from given rules or/and examples, either in linguistic terms or in numerical values to mimic human processes of perception and decision making. The knowledge base is codified in terms of many implicit fuzzy rules. Fuzzy knowledge thus codified may also be compared with explicit rules specified by a human expert. It can also provide a basis for modeling the human operator and allow comparison of what a human operator says to what he does in practice. Two experiments were performed. In the first, control of liquid in a tank, demonstrates how the FERM knowledge base is elicited and trained. The other shows how to use a FERM, build up from linguistic rules, and to control an inverted pendulum without a dynamic model
Decaying Hidden Gauge Boson and the PAMELA and ATIC/PPB-BETS Anomalies
We show that the PAMELA anomaly in the positron fraction as well as the
ATIC/PPB-BETS excesses in the e^- + e^+ flux are simultaneously explained in
our scenario that a hidden U(1)H gauge boson constitutes dark matter of the
Universe and decays into the standard-model particles through a kinetic mixing
with an U(1)B-L gauge boson. Interestingly, the B-L charge assignment
suppresses an antiproton flux in consistent with the PAMELA and BESS
experiments, while the hierarchy between the B-L symmetry breaking scale and
the weak scale naturally leads to the right lifetime of O(10^26) seconds.Comment: the version accepted by Progress of Theoretical Physics (PTP
Approximation of Random Slow Manifolds and Settling of Inertial Particles under Uncertainty
A method is provided for approximating random slow manifolds of a class of
slow-fast stochastic dynamical systems. Thus approximate, low dimensional,
reduced slow systems are obtained analytically in the case of sufficiently
large time scale separation. To illustrate this dimension reduction procedure,
the impact of random environmental fluctuations on the settling motion of
inertial particles in a cellular flow field is examined. It is found that noise
delays settling for some particles but enhances settling for others. A
deterministic stable manifold is an agent to facilitate this phenomenon.
Overall, noise appears to delay the settling in an averaged sense.Comment: 27 pages, 9 figure
Classification of -dimensional metric -Lie algebras
In this paper, we focus on -dimensional metric -Lie algebras. To
begin with, we give some properties on -dimensional -Lie algebras.
Then based on the properties, we obtain the classification of
-dimensional metric -Lie algebras
- …