28,981 research outputs found
Exploiting multi-agent system technology within an autonomous regional active network management system
This paper describes the proposed application of multi-agent system (MAS) technology within AuRA-NMS, an autonomous regional network management system currently being developed in the UK through a partnership between several UK universities, distribution network operators (DNO) and a major equipment manufacturer. The paper begins by describing the challenges facing utilities and why those challenges have led the utilities, a major manufacturer and the UK government to invest in the development of a flexible and extensible active network management system. The requirements the utilities have for a network automation system they wish to deploy on their distribution networks are discussed in detail. With those requirements in mind the rationale behind the use of multi-agent systems (MAS) within AuRA-NMS is presented and the inherent research and design challenges highlighted including: the issues associated with robustness of distributed MAS platforms; the arbitration of different control functions; and the relationship between the ontological requirements of Foundation for Intelligent Physical Agent (FIPA) compliant multi-agent systems, legacy protocols and standards such as IEC 61850 and the common information model (CIM)
Dirac Quantization of the Pais-Uhlenbeck Fourth Order Oscillator
As a model, the Pais-Uhlenbeck fourth order oscillator with equation of
motion
is a quantum-mechanical prototype of a field theory containing both second and
fourth order derivative terms. With its dynamical degrees of freedom obeying
constraints due to the presence of higher order time derivatives, the model
cannot be quantized canonically. We thus quantize it using the method of Dirac
constraints to construct the correct quantum-mechanical Hamiltonian for the
system, and find that the Hamiltonian diagonalizes in the positive and negative
norm states that are characteristic of higher derivative field theories.
However, we also find that the oscillator commutation relations become singular
in the limit, a limit which corresponds to a prototype
of a pure fourth order theory. Thus the particle content of the theory cannot be inferred from that of the
theory; and in fact in the limit we find that all of
the negative norm states move off shell, with the
spectrum of asymptotic in and out states of the equal frequency theory being
found to be completely devoid of states with either negative energy or negative
norm. As a byproduct of our work we find a Pais-Uhlenbeck analog of the zero
energy theorem of Boulware, Horowitz and Strominger, and show how in the equal
frequency Pais-Uhlenbeck theory the theorem can be transformed into a positive
energy theorem instead.Comment: RevTeX4, 20 pages. Final version, to appear in Phys. Rev.
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Ancient Cosmic Dust from Triassic Halite
We describe the discovery of fossil micrometeorites in ancient Triassic rock salt; the first to be found in salt and the oldest complete micrometeorites found to date. We present an estimated flux rate of micrometeorites to Earth at this time
Machine Learning and Irresponsible Inference: Morally Assessing the Training Data for Image Recognition Systems
Just as humans can draw conclusions responsibly or irresponsibly, so too can computers. Machine learning systems that have been trained on data sets that include irresponsible judgments are likely to yield irresponsible predictions as outputs. In this paper I focus on a particular kind of inference a computer system might make: identification of the intentions with which a person acted on the basis of photographic evidence. Such inferences are liable to be morally objectionable, because of a way in which they are presumptuous. After elaborating this moral concern, I explore the possibility that carefully procuring the training data for image recognition systems could ensure that the systems avoid the problem. The lesson of this paper extends beyond just the particular case of image recognition systems and the challenge of responsibly identifying a personâs intentions. Reflection on this particular case demonstrates the importance (as well as the difficulty) of evaluating machine learning systems and their training data from the standpoint of moral considerations that are not encompassed by ordinary assessments of predictive accuracy
Why the Realist-Instrumentalist Debate about Rational Choice Rests on a Mistake
Within the social sciences, much controversy exists about which status should be ascribed to the rationality assumption that forms the core of rational choice theories. Whilst realists argue that the rationality assumption is an empirical claim which describes real processes that cause individual action, instrumentalists maintain that it amounts to nothing more than an analytically set axiom or âas ifâ hypothesis which helps in the generation of accurate predictions. In this paper, I argue that this realist-instrumentalist debate about rational choice theory can be overcome once it is realised that the rationality assumption is neither an empirical description nor an âas ifâ hypothesis, but a normative claim
The generalized Fenyes-Nelson model for free scalar field theory
The generalized Fenyes--Nelson model of quantum mechanics is applied to the
free scalar field. The resulting Markov field is equivalent to the Euclidean
Markov field with the times scaled by a common factor which depends on the
diffusion parameter. This result is consistent between Guerra's earlier work on
stochastic quantization of scalar fields. It suggests a deep connection between
Euclidean field theory and the stochastic interpretation of quantum mechanics.
The question of Lorentz covariance is also discussed.Comment: 6 page
A Tale of Two Impostors: SN2002kg and SN1954J in NGC 2403
We describe new results on two supernova impostors in NGC 2403, SN 1954J(V12)
and SN 2002kg(V37). For the famous object SN 1954J we combine four critical
observations: its current SED, its Halpha emission line profile, the Ca II
triplet in absorption in its red spectrum, and the brightness compared to its
pre-event state. Together these strongly suggest that the survivor is now a hot
supergiant with T ~ 20000 K, a dense wind, substantial circumstellar
extinction, and a G-type supergiant companion. The hot star progenitor of V12's
giant eruption was likely in the post-red supergiant stage and had already shed
a lot of mass. V37 is a classical LBV/S Dor variable. Our photometry and
spectra observed during and after its eruption show that its outburst was an
apparent transit on the HR Diagram due to enhanced mass loss and the formation
of a cooler, dense wind. V37 is an evolved hot supergiant at ~10^6 Lsun with a
probable initial mass of 60 -80 Msun.Comment: To appear in the Astrophysical Journa
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