166,011 research outputs found
Anisotropic Compacts Stars on Paraboloidal Spacetime with Linear Equation of State
New exact solutions of Einstein's field equations (EFEs) by assuming linear
equation of state, where is the radial
pressure and is the surface density, are obtained on the background
of a paraboloidal spacetime. By assuming estimated mass and radius of strange
star candidate 4U 1820-30, various physical and energy conditions are used for
estimating the range of parameter . The suitability of the model for
describing pulsars like PSR J1903+327, Vela X-1, Her X-1 and SAX J1804.3658 has
been explored and respective ranges of , for which all physical and
energy conditions are satisfied throughout the distribution, are obtained.Comment: 10 pages, 12 figures, 1 tabl
Fault tolerant quantum computation with very high threshold for loss errors
Many proposals for fault tolerant quantum computation (FTQC) suffer
detectable loss processes. Here we show that topological FTQC schemes, which
are known to have high error thresholds, are also extremely robust against
losses. We demonstrate that these schemes tolerate loss rates up to 24.9%,
determined by bond percolation on a cubic lattice. Our numerical results show
that these schemes retain good performance when loss and computational errors
are simultaneously present.Comment: 4 pages, comments still very welcome. v2 is a reasonable
approximation to the published versio
21st Century Simulation: Exploiting High Performance Computing and Data Analysis
This paper identifies, defines, and analyzes the limitations imposed on Modeling and Simulation by outmoded
paradigms in computer utilization and data analysis. The authors then discuss two emerging capabilities to
overcome these limitations: High Performance Parallel Computing and Advanced Data Analysis. First, parallel
computing, in supercomputers and Linux clusters, has proven effective by providing users an advantage in
computing power. This has been characterized as a ten-year lead over the use of single-processor computers.
Second, advanced data analysis techniques are both necessitated and enabled by this leap in computing power.
JFCOM's JESPP project is one of the few simulation initiatives to effectively embrace these concepts. The
challenges facing the defense analyst today have grown to include the need to consider operations among non-combatant
populations, to focus on impacts to civilian infrastructure, to differentiate combatants from non-combatants,
and to understand non-linear, asymmetric warfare. These requirements stretch both current
computational techniques and data analysis methodologies. In this paper, documented examples and potential
solutions will be advanced. The authors discuss the paths to successful implementation based on their experience.
Reviewed technologies include parallel computing, cluster computing, grid computing, data logging, OpsResearch,
database advances, data mining, evolutionary computing, genetic algorithms, and Monte Carlo sensitivity analyses.
The modeling and simulation community has significant potential to provide more opportunities for training and
analysis. Simulations must include increasingly sophisticated environments, better emulations of foes, and more
realistic civilian populations. Overcoming the implementation challenges will produce dramatically better insights,
for trainees and analysts. High Performance Parallel Computing and Advanced Data Analysis promise increased
understanding of future vulnerabilities to help avoid unneeded mission failures and unacceptable personnel losses.
The authors set forth road maps for rapid prototyping and adoption of advanced capabilities. They discuss the
beneficial impact of embracing these technologies, as well as risk mitigation required to ensure success
- …