3,096 research outputs found
The ACIGA Data Analysis programme
The Data Analysis programme of the Australian Consortium for Interferometric
Gravitational Astronomy (ACIGA) was set up in 1998 by the first author to
complement the then existing ACIGA programmes working on suspension systems,
lasers and optics, and detector configurations. The ACIGA Data Analysis
programme continues to contribute significantly in the field; we present an
overview of our activities.Comment: 10 pages, 0 figures, accepted, Classical and Quantum Gravity,
(Proceedings of the 5th Edoardo Amaldi Conference on Gravitational Waves,
Tirrenia, Pisa, Italy, 6-11 July 2003
On Using Physical Analogies for Feature and Shape Extraction in Computer Vision
There is a rich literature of approaches to image feature extraction in computer vision. Many sophisticated approaches exist for low- and for high-level feature extraction but can be complex to implement with parameter choice guided by experimentation, but with performance analysis and optimization impeded by speed of computation. We have developed new feature extraction techniques on notional use of physical paradigms, with parametrization aimed to be more familiar to a scientifically trained user, aiming to make best use of computational resource. This paper is the first unified description of these new approaches, outlining the basis and results that can be achieved. We describe how gravitational force can be used for low-level analysis, while analogies of water flow and heat can be deployed to achieve high-level smooth shape detection, by determining features and shapes in a selection of images, comparing results with those by stock approaches from the literature. We also aim to show that the implementation is consistent with the original motivations for these techniques and so contend that the exploration of physical paradigms offers a promising new avenue for new approaches to feature extraction in computer vision
Power quality and electromagnetic compatibility: special report, session 2
The scope of Session 2 (S2) has been defined as follows by the Session Advisory Group and the Technical Committee: Power Quality (PQ), with the more general concept of electromagnetic compatibility (EMC) and with some related safety problems in electricity distribution systems.
Special focus is put on voltage continuity (supply reliability, problem of outages) and voltage quality (voltage level, flicker, unbalance, harmonics). This session will also look at electromagnetic compatibility (mains frequency to 150 kHz), electromagnetic interferences and electric and magnetic fields issues. Also addressed in this session are electrical safety and immunity concerns (lightning issues, step, touch and transferred voltages).
The aim of this special report is to present a synthesis of the present concerns in PQ&EMC, based on all selected papers of session 2 and related papers from other sessions, (152 papers in total). The report is divided in the following 4 blocks:
Block 1: Electric and Magnetic Fields, EMC, Earthing systems
Block 2: Harmonics
Block 3: Voltage Variation
Block 4: Power Quality Monitoring
Two Round Tables will be organised:
- Power quality and EMC in the Future Grid (CIGRE/CIRED WG C4.24, RT 13)
- Reliability Benchmarking - why we should do it? What should be done in future? (RT 15
Swarm-intelligent search for gravitational waves from eccentric binary mergers
We implement an eccentric search for compact binary mergers based on particle
swarm optimization. The orbital eccentricity is an invaluable input for
understanding the formation scenarios of the binary mergers and can play a
pivotal role in finding their electromagnetic counterparts. Current modelled
searches rely on pre-computed template banks that are computationally expensive
and resistant towards expanding the search parameter space dimensionality. On
the other hand, particle swarm optimization offers a straightforward algorithm
that dynamically selects template points while exploring an arbitrary
dimensional parameter space. Through extensive evaluation using simulated
signals from spin-aligned eccentric binary mergers, we discovered that the
search exhibits a remarkable autonomy in capturing the effects of both
eccentricity and spin. We describe our search pipeline and revisit some of the
merger candidates from the gravitational wave transient catalogs
Leo: Lagrange Elementary Optimization
Global optimization problems are frequently solved using the practical and
efficient method of evolutionary sophistication. But as the original problem
becomes more complex, so does its efficacy and expandability. Thus, the purpose
of this research is to introduce the Lagrange Elementary Optimization (Leo) as
an evolutionary method, which is self-adaptive inspired by the remarkable
accuracy of vaccinations using the albumin quotient of human blood. They
develop intelligent agents using their fitness function value after gene
crossing. These genes direct the search agents during both exploration and
exploitation. The main objective of the Leo algorithm is presented in this
paper along with the inspiration and motivation for the concept. To demonstrate
its precision, the proposed algorithm is validated against a variety of test
functions, including 19 traditional benchmark functions and the CECC06 2019
test functions. The results of Leo for 19 classic benchmark test functions are
evaluated against DA, PSO, and GA separately, and then two other recent
algorithms such as FDO and LPB are also included in the evaluation. In
addition, the Leo is tested by ten functions on CECC06 2019 with DA, WOA, SSA,
FDO, LPB, and FOX algorithms distinctly. The cumulative outcomes demonstrate
Leo's capacity to increase the starting population and move toward the global
optimum. Different standard measurements are used to verify and prove the
stability of Leo in both the exploration and exploitation phases. Moreover,
Statistical analysis supports the findings results of the proposed research.
Finally, novel applications in the real world are introduced to demonstrate the
practicality of Leo.Comment: 28 page
First Season QUIET Observations: Measurements of Cosmic Microwave Background Polarization Power Spectra at 43 GHz in the Multipole Range 25 †â †475
The Q/U Imaging ExperimenT (QUIET) employs coherent receivers at 43 GHz and 94 GHz, operating on the Chajnantor plateau in the Atacama Desert in Chile, to measure the anisotropy in the polarization of the cosmic microwave background (CMB). QUIET primarily targets the B modes from primordial gravitational waves. The combination of these frequencies gives sensitivity to foreground contributions from diffuse Galactic synchrotron radiation. Between 2008 October and 2010 December, over 10,000 hr of data were collected, first with the 19 element 43 GHz array (3458 hr) and then with the 90 element 94 GHz array. Each array observes the same four fields, selected for low foregrounds, together covering â1000 deg^2. This paper reports initial results from the 43 GHz receiver, which has an array sensitivity to CMB fluctuations of 69 ÎŒKâs. The data were extensively studied with a large suite of null tests before the power spectra, determined with two independent pipelines, were examined. Analysis choices, including data selection, were modified until the null tests passed. Cross-correlating maps with different telescope pointings is used to eliminate a bias. This paper reports the EE, BB, and EB power spectra in the multipole range â = 25-475. With the exception of the lowest multipole bin for one of the fields, where a polarized foreground, consistent with Galactic synchrotron radiation, is detected with 3Ï significance, the E-mode spectrum is consistent with the ÎCDM model, confirming the only previous detection of the first acoustic peak. The B-mode spectrum is consistent with zero, leading to a measurement of the tensor-to-scalar ratio of r = 0.35^(+1.06)_(â0.87). The combination of a new time-stream "double-demodulation" technique, side-fed Dragonian optics, natural sky rotation, and frequent boresight rotation leads to the lowest level of systematic contamination in the B-mode power so far reported, below the level of r = 0.1
First Season QUIET Observations: Measurements of CMB Polarization Power Spectra at 43 GHz in the Multipole Range 25 <= ell <= 475
The Q/U Imaging ExperimenT (QUIET) employs coherent receivers at 43GHz and
95GHz, operating on the Chajnantor plateau in the Atacama Desert in Chile, to
measure the anisotropy in the polarization of the CMB. QUIET primarily targets
the B modes from primordial gravitational waves. The combination of these
frequencies gives sensitivity to foreground contributions from diffuse Galactic
synchrotron radiation. Between 2008 October and 2010 December, >10,000hours of
data were collected, first with the 19-element 43GHz array (3458hours) and then
with the 90-element 95GHz array. Each array observes the same four fields,
selected for low foregrounds, together covering ~1000deg^2. This paper reports
initial results from the 43GHz receiver which has an array sensitivity to CMB
fluctuations of 69uK sqrt(s). The data were extensively studied with a large
suite of null tests before the power spectra, determined with two independent
pipelines, were examined. Analysis choices, including data selection, were
modified until the null tests passed. Cross correlating maps with different
telescope pointings is used to eliminate a bias. This paper reports the EE, BB
and EB power spectra in the multipole range ell=25-475. With the exception of
the lowest multipole bin for one of the fields, where a polarized foreground,
consistent with Galactic synchrotron radiation, is detected with 3sigma
significance, the E-mode spectrum is consistent with the LCDM model, confirming
the only previous detection of the first acoustic peak. The B-mode spectrum is
consistent with zero, leading to a measurement of the tensor-to-scalar ratio of
r=0.35+1.06-0.87. The combination of a new time-stream double-demodulation
technique, Mizuguchi-Dragone optics, natural sky rotation, and frequent
boresight rotation leads to the lowest level of systematic contamination in the
B-mode power so far reported, below the level of r=0.1Comment: 19 pages, 14 figures, higher quality figures are available at
http://quiet.uchicago.edu/results/index.html; Fixed a typo and corrected
statistical error values used as a reference in Figure 14, showing our
systematic uncertainties (unchanged) vs. multipole; Revision to ApJ accepted
version, this paper should be cited as "QUIET Collaboration et al. (2011)
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