43,647 research outputs found
FLECS: Planning with a Flexible Commitment Strategy
There has been evidence that least-commitment planners can efficiently handle
planning problems that involve difficult goal interactions. This evidence has
led to the common belief that delayed-commitment is the "best" possible
planning strategy. However, we recently found evidence that eager-commitment
planners can handle a variety of planning problems more efficiently, in
particular those with difficult operator choices. Resigned to the futility of
trying to find a universally successful planning strategy, we devised a planner
that can be used to study which domains and problems are best for which
planning strategies. In this article we introduce this new planning algorithm,
FLECS, which uses a FLExible Commitment Strategy with respect to plan-step
orderings. It is able to use any strategy from delayed-commitment to
eager-commitment. The combination of delayed and eager operator-ordering
commitments allows FLECS to take advantage of the benefits of explicitly using
a simulated execution state and reasoning about planning constraints. FLECS can
vary its commitment strategy across different problems and domains, and also
during the course of a single planning problem. FLECS represents a novel
contribution to planning in that it explicitly provides the choice of which
commitment strategy to use while planning. FLECS provides a framework to
investigate the mapping from planning domains and problems to efficient
planning strategies.Comment: See http://www.jair.org/ for an online appendix and other files
accompanying this articl
The Skyrme Interaction in finite nuclei and nuclear matter
Self-consistent mean-field models are a powerful tool in the investigation of
nuclear structure and low-energy dynamics. They are based on effective
energy-density functionals, often formulated in terms of effective
density-dependent nucleon-nucleon interactions. The free parameters of the
functional are adjusted to empirical data. A proper choice of these parameters
requires a comprehensive set of constraints covering experimental data on
finite nuclei, concerning static as well as dynamical properties, empirical
characteristics of nuclear matter, and observational information on
nucleosynthesis, neutron stars and supernovae. This work aims at a
comprehensive survey of the performance of one of the most successful
non-relativistic self-consistent method, the Skyrme-Hartree-Fock model (SHF),
with respect to these constraints. A full description of the Skyrme functional
is given and its relation to other effective interactions is discussed. The
validity of the application of SHF far from stability and in dense environments
beyond the nuclear saturation density is critically assessed. The use of SHF in
models extended beyond the mean field approximation by including some
correlations is discussed. Finally, future prospects for further development of
SHF towards a more consistent application of the existing and promisingly newly
developing constraints are outlined.Comment: 71 pages, 22 figures. Accepted for publication in Prog.Part.Nucl.Phy
Design and evaluation of experimental ceramic automobile thermal reactors
The results obtained in an exploratory evaluation of ceramics for automobile thermal reactors are summarized. Candidate ceramic materials were evaluated in several reactor designs by using both engine-dynamometer and vehicle road tests. Silicon carbide contained in a corrugated-metal support structure exhibited the best performance, lasting 1100 hr in engine-dynamometer tests and more than 38,600 km (24000 miles) in vehicle road tests. Although reactors containing glass-ceramic components did not perform as well as those containing silicon carbide, the glass-ceramics still offer good potential for reactor use with improved reactor designs
Luttinger States at the Edge
An effective wavefunction for the edge excitations in the Fractional quantum
Hall effect can be found by dimensionally reducing the bulk wavefunction.
Treated this way the Laughlin wavefunction yields a Luttinger
model ground state. We identify the edge-electron field with a Luttinger
hyper-fermion operator, and the edge electron itself with a non-backscattering
Bogoliubov quasi-particle. The edge-electron propagator may be calculated
directly from the effective wavefunction using the properties of a
one-dimensional one-component plasma, provided a prescription is adopted which
is sensitive to the extra flux attached to the electrons
Decorrelation control by the cerebellum achieves oculomotor plant compensation in simulated vestibulo-ocular reflex
We introduce decorrelation control as a candidate algorithm for the cerebellar microcircuit and demonstrate its utility for oculomotor plant compensation in a linear model of the vestibulo-ocular reflex (VOR). Using an adaptive-filter representation of cerebellar cortex and an anti-Hebbian learning rule, the algorithm learnt to compensate for the oculomotor plant by minimizing correlations between a predictor variable (eye-movement command) and a target variable (retinal slip), without requiring a motor-error signal. Because it also provides an estimate of the unpredicted component of the target variable, decorrelation control can simplify both motor coordination and sensory acquisition. It thus unifies motor and sensory cerebellar functions
A study of how middle leaders in a secondary school are making sense of their role in relation to teachers’ professional development
At a time when the provision for initial teacher training and the continuous professional development of new and experienced teaching professionals is increasingly becoming more school-based, it would appear that a central piece of knowledge concerning teachers’ professional development has been overlooked: middle leaders, who are acknowledged as playing an important role in teacher development, have received little consideration in the academic discourse. In response to this lack of attention, this thesis examines how a small group of four experienced middle leaders in a mainstream secondary school are making sense of their role in relation to teachers’ professional development.
The data collected within the study was analysed using interpretative phenomenological analysis (IPA), which allowed the middle leaders’ perceptions, reasoning and feelings to be revealed in one master theme and five super-ordinate themes. To further strengthen the thematic analysis, the master theme of relationships was considered against Hoyle’s conceptual framework of extended and restricted professionality.
Teacher voice is central to this thesis and its findings. The research provides evidence to suggest that due to a lack of recognition of teacher voice, the middle leaders in this study are closing down external professional learning opportunities and are predominately looking inwards towards their departments and colleagues to facilitate teacher development. In doing so, the middle leaders are able to remain true to the relationshipcentred practice that they value, but are failing to perceive teacher development as a holistic process that has the potential to project their professionalism outwards across professional boundaries
Exploring the use of Controlled English for communication with ACT-R agents
Research is being undertaken into sense-making by collaborative agents, based upon a cognitive framework of human behaviour, ACT-R, together with communication between the agents. We explore the use of Controlled English for this purpos
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