39,837 research outputs found
Authorization and access control of application data in Workflow systems
Workflow Management Systems (WfMSs) are used to support the modeling and coordinated execution of business processes within an organization or across organizational boundaries. Although some research efforts have addressed requirements for authorization and access control for workflow systems, little attention has been paid to the requirements as they apply to application data accessed or managed by WfMSs. In this paper, we discuss key access control requirements for application data in workflow applications using examples from the healthcare domain, introduce a classification of application data used in workflow systems by analyzing their sources, and then propose a comprehensive data authorization and access control mechanism for WfMSs. This involves four aspects: role, task, process instance-based user group, and data content. For implementation, a predicate-based access control method is used. We believe that the proposed model is applicable to workflow applications and WfMSs with diverse access control requirements
The influence of strange quarks on QCD phase diagram and chemical freeze-out: Results from the hadron resonance gas model
We confront the lattice results on QCD phase diagram for two and three
flavors with the hadron resonance gas model. Taking into account the
truncations in the Taylor-expansion of energy density done on the
lattice at finite chemical potential , we find that the hadron resonance
gas model under the condition of constant describes very well the
lattice phase diagram. We also calculate the chemical freeze-out curve
according to the entropy density . The -values are taken from lattice QCD
simulations with two and three flavors. We find that this condition is
excellent in reproducing the experimentally estimated parameters of the
chemical freeze-out.Comment: 5 pages, 3 figures and 1 table Talk given at VIIIth international
conference on ''Strangeness in Quark Matter'' (SQM 2004), Cape Town, South
Africa, Sep. 15-20 200
A probabilistic model checking approach to analysing reliability, availability, and maintainability of a single satellite system
Satellites now form a core component for space
based systems such as GPS and GLONAS which provide
location and timing information for a variety of uses. Such
satellites are designed to operate in-orbit and have lifetimes of
10 years or more. Reliability, availability and maintainability
(RAM) analysis of these systems has been indispensable in
the design phase of satellites in order to achieve minimum
failures or to increase mean time between failures (MTBF)
and thus to plan maintainability strategies, optimise reliability
and maximise availability. In this paper, we present formal
modelling of a single satellite and logical specification of
its reliability, availability and maintainability properties. The
probabilistic model checker PRISM has been used to perform
automated quantitative analyses of these properties
Mapping Atomic Motions with Electrons: Toward the Quantum Limit to Imaging Chemistry
Recent advances in ultrafast electron and X-ray diffraction have pushed imaging of structural dynamics into the femtosecond time domain, that is, the fundamental time scale of atomic motion. New physics can be reached beyond the scope of traditional diffraction or reciprocal space imaging. By exploiting the high time resolution, it has been possible to directly observe the collapse of nearly innumerable possible nuclear motions to a few key reaction modes that direct chemistry. It is this reduction in dimensionality in the transition state region that makes chemistry a transferable concept, with the same class of reactions being applicable to synthetic strategies to nearly arbitrary levels of complexity. The ability to image the underlying key reaction modes has been achieved with resolution to relative changes in atomic positions to better than 0.01 Å, that is, comparable to thermal motions. We have effectively reached the fundamental space-time limit with respect to the reaction energetics and imaging the acting forces. In the process of ensemble measured structural changes, we have missed the quantum aspects of chemistry. This perspective reviews the current state of the art in imaging chemistry in action and poses the challenge to access quantum information on the dynamics. There is the possibility with the present ultrabright electron and X-ray sources, at least in principle, to do tomographic reconstruction of quantum states in the form of a Wigner function and density matrix for the vibrational, rotational, and electronic degrees of freedom. Accessing this quantum information constitutes the ultimate demand on the spatial and temporal resolution of reciprocal space imaging of chemistry. Given the much shorter wavelength and corresponding intrinsically higher spatial resolution of current electron sources over X-rays, this Perspective will focus on electrons to provide an overview of the challenge on both the theory and the experimental fronts to extract the quantum aspects of molecular dynamics
Approximations of thermoelastic and viscoelastic control systems
Well-posed models and computational algorithms are developed and analyzed for control of a class of partial differential equations that describe the motions of thermo-viscoelastic structures. An abstract (state space) framework and a general well-posedness result are presented that can be applied to a large class of thermo-elastic and thermo-viscoelastic models. This state space framework is used in the development of a computational scheme to be used in the solution of a linear quadratic regulator (LQR) control problem. A detailed convergence proof is provided for the viscoelastic model and several numerical results are presented to illustrate the theory and to analyze problems for which the theory is incomplete
On gaugino condensation in the effective theory
We analyze the gaugino condensation in the effective theory for N=1 SU(N)
Supersymmetric QCD with flavors. It is known that taking the vacuum
expectation value of the matter field to be infinite, we can show that gaugino
condensation can occur. At such a limit we should consider only pure
supersymmetric Yang-Mills theory. But when we include an interaction term of
order , the situation can change. We analyze the effect of this
interaction term and examine the gaugino condensation in the low energy
Yang-Mills theory by using the scheme of Nambu-Jona-Lasinio.Comment: 5 pages, Plain Late
Directed percolation with a single defect site
In a recent study [arXiv:1011.3254] the contact process with a modified
creation rate at a single site was shown to exhibit a non-universal scaling
behavior with exponents varying with the creation rate at the special site. In
the present work we argue that the survival probability decays according to a
stretched exponential rather than a power law, explaining previous
observations.Comment: 8 pages, 3 figure
Experiments on Sonoluminescence: Possible Nuclear and QED Aspects and Optical Applications
Experiments aimed at testing some hypothesis about the nature of Single
Bubble Sonoluminescence are discussed. A possibility to search for micro-traces
of thermonuclear neutrons is analyzed, with the aid of original low-background
neutron counter operating under conditions of the deep shielding from Cosmic
and other sources of background. Besides, some signatures of QED-contribution
to the light emission in SBSL are under the consideration, as well as new
approaches to probe a temperature inside the bubble. An applied-physics portion
of the program is presented also, in which an attention is being paid to
single- and a few-pulse light sources on the basis of SBSL.Comment: 4 pages; to be published by AIP in the Proc. ISNA-1
The QCD phase diagram: A comparison of lattice and hadron resonance gas model calculations
We compare the lattice results on QCD phase diagram for two and three flavors
with the hadron resonance gas model (HRGM) calculations. Lines of constant
energy density have been determined at different baryo-chemical
potentials . For the strangeness chemical potentials , we use two
models. In one model, we explicitly set for all temperatures and
baryo-chemical potentials. This assignment is used in lattice calculations. In
the other model, is calculated in dependence on and
according to the condition of vanishing strangeness. We also derive an
analytical expression for the dependence of on by applying
Taylor expansion of . In both cases, we compare HRGM results on
diagram with the lattice calculations. The agreement is excellent,
especially when the trigonometric function of is truncated up to the
same order as done in lattice simulations. For studying the efficiency of the
truncated Taylor expansion, we calculate the radius of convergence. For zero-
and second-order radii, the agreement with lattice is convincing. Furthermore,
we make predictions for QCD phase diagram for non-truncated expressions and
physical masses. These predictions are to be confirmed by heavy-ion experiments
and future lattice calculations with very small lattice spacing and physical
quark masses.Comment: 25 pages, 8 eps figure
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