17,261 research outputs found
Quantum Information Paradox: Real or Fictitious?
One of the outstanding puzzles of theoretical physics is whether quantum
information indeed gets lost in the case of Black Hole (BH) evaporation or
accretion. Let us recall that Quantum Mechanics (QM) demands an upper limit on
the acceleration of a test particle. On the other hand, it is pointed out here
that, if a Schwarzschild BH would exist, the acceleration of the test particle
would blow up at the event horizon in violation of QM. Thus the concept of an
exact BH is in contradiction of QM and quantum gravity (QG). It is also
reminded that the mass of a BH actually appears as an INTEGRATION CONSTANT of
Einstein equations. And it has been shown that the value of this integration
constant is actually zero. Thus even classically, there cannot be finite mass
BHs though zero mass BH is allowed. It has been further shown that during
continued gravitational collapse, radiation emanating from the contracting
object gets trapped within it by the runaway gravitational field. As a
consequence, the contracting body attains a quasi-static state where outward
trapped radiation pressure gets balanced by inward gravitational pull and the
ideal classical BH state is never formed in a finite proper time. In other
words, continued gravitational collapse results in an "Eternally Collapsing
Object" which is a ball of hot plasma and which is asymptotically approaching
the true BH state with M=0 after radiating away its entire mass energy. And if
we include QM, this contraction must halt at a radius suggested by highest QM
acceleration. In any case no EH is ever formed and in reality, there is no
quantum information paradox.Comment: 8 pages in Pramana Style, 6 in Revtex styl
A note on the entropy of charged multi - black - holes
Majumdar--Papapetrou multi--black-hole solutions of the Einstein--Maxwell
equations are considered in four and higher dimensions. The Euclidean action
with boundary conditions appropriate to the canonical ensemble is shown to lead
to zero entropy.Comment: LaTeX, 8 page
Multiscale Morphological Filtering for Analysis of Noisy and Complex Images
Images acquired with passive sensing techniques suffer from illumination variations and poor local contrasts that create major difficulties in interpretation and identification tasks. On the other hand, images acquired with active sensing techniques based on monochromatic illumination are degraded with speckle noise. Mathematical morphology offers elegant techniques to handle a wide range of image degradation problems. Unlike linear filters, morphological filters do not blur the edges and hence maintain higher image resolution. Their rich mathematical framework facilitates the design and analysis of these filters as well as their hardware implementation. Morphological filters are easier to implement and are more cost effective and efficient than several conventional linear filters. Morphological filters to remove speckle noise while maintaining high resolution and preserving thin image regions that are particularly vulnerable to speckle noise were developed and applied to SAR imagery. These filters used combination of linear (one-dimensional) structuring elements in different (typically four) orientations. Although this approach preserves more details than the simple morphological filters using two-dimensional structuring elements, the limited orientations of one-dimensional elements approximate the fine details of the region boundaries. A more robust filter designed recently overcomes the limitation of the fixed orientations. This filter uses a combination of concave and convex structuring elements. Morphological operators are also useful in extracting features from visible and infrared imagery. A multiresolution image pyramid obtained with successive filtering and a subsampling process aids in the removal of the illumination variations and enhances local contrasts. A morphology-based interpolation scheme was also introduced to reduce intensity discontinuities created in any morphological filtering task. The generality of morphological filtering techniques in extracting information from a wide variety of images obtained with active and passive sensing techniques is discussed. Such techniques are particularly useful in obtaining more information from fusion of complex images by different sensors such as SAR, visible, and infrared
Periodically Controlled Hybrid Systems: Verifying A Controller for An Autonomous Vehicle
This paper introduces Periodically Controlled Hybrid Automata (PCHA) for describing a class of hybrid control systems. In a PCHA, control actions occur roughly periodically while internal and input actions, may occur in the interim changing the discrete-state or the setpoint. Based on periodicity and subtangential conditions, a new sufficient condition for verifying invariance of PCHAs is presented. This technique is used in verifying safety of the planner-controller subsystem of an autonomous ground vehicle, and in deriving geometric properties of planner generated paths that can be followed safely by the controller under environmental uncertainties
Active Classification: Theory and Application to Underwater Inspection
We discuss the problem in which an autonomous vehicle must classify an object
based on multiple views. We focus on the active classification setting, where
the vehicle controls which views to select to best perform the classification.
The problem is formulated as an extension to Bayesian active learning, and we
show connections to recent theoretical guarantees in this area. We formally
analyze the benefit of acting adaptively as new information becomes available.
The analysis leads to a probabilistic algorithm for determining the best views
to observe based on information theoretic costs. We validate our approach in
two ways, both related to underwater inspection: 3D polyhedra recognition in
synthetic depth maps and ship hull inspection with imaging sonar. These tasks
encompass both the planning and recognition aspects of the active
classification problem. The results demonstrate that actively planning for
informative views can reduce the number of necessary views by up to 80% when
compared to passive methods.Comment: 16 page
On the log correction to the black hole area law
Various approaches to black hole entropy yield the area law with logarithmic
corrections, many involving a coefficient 1/2, and some involving 3/2. It is
pointed out here that the standard quantum geometry formalism is not consistent
with 3/2 and favours 1/2.Comment: 4 pages; added new result
Deformation Projected RMF Calculation for Cr and Fe nuclei in Hybrid Derivative Coupling Model
The ground state properties of even mass Cr and Fe isotopes are studied using
the generalized hybrid derivative coupling model. The energy surface of each
isotope is plotted as a function of the mass quadrupole moment. The neutron
numbers N=20 and N=40 are seen to remain magic numbers but N= 28 and 50 are
predicted to be non-magic. The neutron number N=70 turns out to be a magic
number according to the present calculation. In all the isotopes studied the
calculated binding energy values are less than those obtained from experiment
while the deformation is in better agreement.Comment: To appear in Int. Jour. Mod. Phys.
Baryon Self-Energy With QQQ Bethe-Salpeter Dynamics In The Non-Perturbative QCD Regime: n-p Mass Difference
A qqq BSE formalism based on DB{\chi}S of an input 4-fermion Lagrangian of
`current' u,d quarks interacting pairwise via gluon-exchange-propagator in its
{\it non-perturbative} regime, is employed for the calculation of baryon
self-energy via quark-loop integrals. To that end the baryon-qqq vertex
function is derived under Covariant Instantaneity Ansatz (CIA), using Green's
function techniques. This is a 3-body extension of an earlier q{\bar q}
(2-body) result on the exact 3D-4D interconnection for the respective BS wave
functions under 3D kernel support, precalibrated to both q{\bar q} and qqq
spectra plus other observables. The quark loop integrals for the neutron (n) -
proton (p) mass difference receive contributions from : i) the strong SU(2)
effect arising from the d-u mass difference (4 MeV); ii) the e.m. effect of the
respective quark charges. The resultant n-p difference comes dominantly from
d-u effect (+1.71 Mev), which is mildly offset by e.m.effect (-0.44), subject
to gauge corrections. To that end, a general method for QED gauge corrections
to an arbitrary momentum dependent vertex function is outlined, and on on a
proportionate basis from the (two-body) kaon case, the net n-p difference works
out at just above 1 MeV. A critical comparison is given with QCD sum rules
results.Comment: be 27 pages, Latex file, and to be published in IJMPA, Vol 1
Regression Based Scenario Generation: Applications For Performance Management
Regression analysis is a common tool in performance management and measurement in industry. Many firms wish to optimise their performance using Stochastic Programming but to the best of our knowledge there exists no scenario generation method for regression models. In this paper we propose a new scenario generation method for linear regression used in performance management. Our scenario generation method is able to produce more representative scenarios by utilising the data driven properties of linear regression models and cluster based resampling. Secondly, our scenario generation method is more robust to model âoverfittingâ by utilising a multiple of linear regression functions, hence our scenarios are more reliable. Finally, our scenario generation method enables parsimonious incorporation of decision analysis, such as worst case scenarios, hence our scenario generation facilitates decision making. This paper will also be of interest to industry professionals
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