23,761 research outputs found
Towards Consistency Management for a Business-Driven Development of SOA
The usage of the Service Oriented Architecture
(SOA) along with the Business Process Management has emerged
as a valuable solution for the complex (business process driven)
system engineering. With a Model Driven Engineering where the
business process models drive the supporting service component
architectures, less effort is gone into the Business/IT alignment
during the initial development activities, and the IT developers
can rapidly proceed with the SOA implementation. However, the
difference between the design principles of the emerging domainspecific
languages imposes serious challenges in the following
re-design phases. Moreover, enabling evolutions on the business
process models while keeping them synchronized with the underlying
software architecture models is of high relevance to the key
elements of any Business Driven Development (BDD). Given a
business process update, this paper introduces an incremental
model transformation approach that propagates this update
to the related service component configurations. It, therefore,
supports the change propagation among heterogenous domainspecific
languages, e.g., the BPMN and the SCA. As a major
contribution, our approach makes model transformation more
tractable to reconfigure system architecture without disrupting its
structural consistency. We propose a synchronizer that provides
the BPMN-to-SCA model synchronization with the help of the
conditional graph rewriting
The inconsistency of French regulation mode faced with the financialization of accumulation pattern.
The absence of specifically dedicated method to represent financialized capitalism constitutes a significant gap in contemporary macroeconomic modelling considering the impact of finance on the rules of wealth production and distribution. From both the lessons of Regulation theory in terms of accumulation pattern and regulation mode declined through the concepts of institutional hierarchy and complementarity, and the neo-Cambridgian modelling framework, one tries to establish the causes which prevail in the divergence of American and French economies in the adoption of finance-led capitalism.modelling and macroeconomic simulation; institutional complementarity and hierarchy; accumulation regime; regulation pattern; financialization.
Chimera: A hybrid approach to numerical loop quantum cosmology
The existence of a quantum bounce in isotropic spacetimes is a key result in
loop quantum cosmology (LQC), which has been demonstrated to arise in all the
models studied so far. In most of the models, the bounce has been studied using
numerical simulations involving states which are sharply peaked and which
bounce at volumes much larger than the Planck volume. An important issue is to
confirm the existence of the bounce for states which have a wide spread, or
which bounce closer to the Planck volume. Numerical simulations with such
states demand large computational domains, making them very expensive and
practically infeasible with the techniques which have been implemented so far.
To overcome these difficulties, we present an efficient hybrid numerical scheme
using the property that at the small spacetime curvature, the quantum
Hamiltonian constraint in LQC, which is a difference equation with uniform
discretization in volume, can be approximated by a Wheeler-DeWitt differential
equation. By carefully choosing a hybrid spatial grid allowing the use of
partial differential equations at large volumes, and with a simple change of
geometrical coordinate, we obtain a surprising reduction in the computational
cost. This scheme enables us to explore regimes which were so far unachievable
for the isotropic model in LQC. Our approach also promises to significantly
reduce the computational cost for numerical simulations in anisotropic LQC
using high performance computing.Comment: Minor revision to match published version. To appear in CQ
Accretion disks around binary black holes of unequal mass: GRMHD simulations near decoupling
We report on simulations in general relativity of magnetized disks onto black
hole binaries. We vary the binary mass ratio from 1:1 to 1:10 and evolve the
systems when they orbit near the binary-disk decoupling radius. We compare
(surface) density profiles, accretion rates (relative to a single, non-spinning
black hole), variability, effective -stress levels and luminosities as
functions of the mass ratio. We treat the disks in two limiting regimes: rapid
radiative cooling and no radiative cooling. The magnetic field lines clearly
reveal jets emerging from both black hole horizons and merging into one common
jet at large distances. The magnetic fields give rise to much stronger shock
heating than the pure hydrodynamic flows, completely alter the disk structure,
and boost accretion rates and luminosities. Accretion streams near the horizons
are among the densest structures; in fact, the 1:10 no-cooling evolution
results in a refilling of the cavity. The typical effective temperature in the
bulk of the disk is yielding characteristic thermal frequencies . These systems are
thus promising targets for many extragalactic optical surveys, such as LSST,
WFIRST, and PanSTARRS.Comment: 29 pages, 23 captioned figures, 3 tables, submitted to PR
High accuracy binary black hole simulations with an extended wave zone
We present results from a new code for binary black hole evolutions using the
moving-puncture approach, implementing finite differences in generalised
coordinates, and allowing the spacetime to be covered with multiple
communicating non-singular coordinate patches. Here we consider a regular
Cartesian near zone, with adapted spherical grids covering the wave zone. The
efficiencies resulting from the use of adapted coordinates allow us to maintain
sufficient grid resolution to an artificial outer boundary location which is
causally disconnected from the measurement. For the well-studied test-case of
the inspiral of an equal-mass non-spinning binary (evolved for more than 8
orbits before merger), we determine the phase and amplitude to numerical
accuracies better than 0.010% and 0.090% during inspiral, respectively, and
0.003% and 0.153% during merger. The waveforms, including the resolved higher
harmonics, are convergent and can be consistently extrapolated to
throughout the simulation, including the merger and ringdown. Ringdown
frequencies for these modes (to ) match perturbative
calculations to within 0.01%, providing a strong confirmation that the remnant
settles to a Kerr black hole with irreducible mass and spin $S_f/M_f^2 = 0.686923 \pm 10\times10^{-6}
Implementation of higher-order absorbing boundary conditions for the Einstein equations
We present an implementation of absorbing boundary conditions for the
Einstein equations based on the recent work of Buchman and Sarbach. In this
paper, we assume that spacetime may be linearized about Minkowski space close
to the outer boundary, which is taken to be a coordinate sphere. We reformulate
the boundary conditions as conditions on the gauge-invariant
Regge-Wheeler-Zerilli scalars. Higher-order radial derivatives are eliminated
by rewriting the boundary conditions as a system of ODEs for a set of auxiliary
variables intrinsic to the boundary. From these we construct boundary data for
a set of well-posed constraint-preserving boundary conditions for the Einstein
equations in a first-order generalized harmonic formulation. This construction
has direct applications to outer boundary conditions in simulations of isolated
systems (e.g., binary black holes) as well as to the problem of
Cauchy-perturbative matching. As a test problem for our numerical
implementation, we consider linearized multipolar gravitational waves in TT
gauge, with angular momentum numbers l=2 (Teukolsky waves), 3 and 4. We
demonstrate that the perfectly absorbing boundary condition B_L of order L=l
yields no spurious reflections to linear order in perturbation theory. This is
in contrast to the lower-order absorbing boundary conditions B_L with L<l,
which include the widely used freezing-Psi_0 boundary condition that imposes
the vanishing of the Newman-Penrose scalar Psi_0.Comment: 25 pages, 9 figures. Minor clarifications. Final version to appear in
Class. Quantum Grav
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