266 research outputs found
Deterministically Driven Avalanche Models of Solar Flares
We develop and discuss the properties of a new class of lattice-based
avalanche models of solar flares. These models are readily amenable to a
relatively unambiguous physical interpretation in terms of slow twisting of a
coronal loop. They share similarities with other avalanche models, such as the
classical stick--slip self-organized critical model of earthquakes, in that
they are driven globally by a fully deterministic energy loading process. The
model design leads to a systematic deficit of small scale avalanches. In some
portions of model space, mid-size and large avalanching behavior is scale-free,
being characterized by event size distributions that have the form of
power-laws with index values, which, in some parameter regimes, compare
favorably to those inferred from solar EUV and X-ray flare data. For models
using conservative or near-conservative redistribution rules, a population of
large, quasiperiodic avalanches can also appear. Although without direct
counterparts in the observational global statistics of flare energy release,
this latter behavior may be relevant to recurrent flaring in individual coronal
loops. This class of models could provide a basis for the prediction of large
solar flares.Comment: 24 pages, 11 figures, 2 tables, accepted for publication in Solar
Physic
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Catalytic pyrolysis of plastic wastes - Towards an economically viable process
The ultimate goal of our project is an economically viable pyrolysis process to recover useful fuels and/or chemicals from plastics- containing wastes. This paper reports the effects of various promoted and unpromoted binary oxide catalysts on yields and compositions of liquid organic products, as measured in a small laboratory pyrolysis reactor. On the basis of these results, a commercial scale catalytic pyrolysis reactor was simulated by the Aspen software and rough costs were estimated. The results suggest that such a process has potential economic viability
Quantum Mechanics Model on K\"ahler conifold
We propose an exactly-solvable model of the quantum oscillator on the class
of K\"ahler spaces (with conic singularities), connected with two-dimensional
complex projective spaces. Its energy spectrum is nondegenerate in the orbital
quantum number, when the space has non-constant curvature. We reduce the model
to a three-dimensional system interacting with the Dirac monopole. Owing to
noncommutativity of the reduction and quantization procedures, the Hamiltonian
of the reduced system gets non-trivial quantum corrections. We transform the
reduced system into a MIC-Kepler-like one and find that quantum corrections
arise only in its energy and coupling constant. We present the exact spectrum
of the generalized MIC-Kepler system. The one-(complex) dimensional analog of
the suggested model is formulated on the Riemann surface over the complex
projective plane and could be interpreted as a system with fractional spin.Comment: 5 pages, RevTeX format, some misprints heve been correcte
Simultaneous saccharification and fermentation of steam exploded duckweed: Improvement of the ethanol yield by increasing yeast titre
This study investigated the conversion of Lemna minor biomass to bioethanol. The biomass was pre-treated by steam explosion (SE, 210 °C, 10 min) and then subjected to simultaneous saccharification and fermentation (SSF) using CellicÒ CTec 2 (20 U or 0.87 FPU gﰂ1 substrate) cellulase plus b-glucosidase (2 U gﰂ1 substrate) and a yeast inoculum of 10% (v/v or 8.0 ﰀ 107 cells mLﰂ1). At a substrate concentration of 1% (w/v) an ethanol yield of 80% (w/w, theoretical) was achieved. However at a substrate concentration of 20% (w/v), the ethanol yield was lowered to 18.8% (w/w, theoretical). Yields were considerably improved by increasing the yeast titre in the inoculum or preconditioning the yeast on steam exploded liquor. These approaches enhanced the ethanol yield up to 70% (w/w, theoretical) at a substrate concen- tration of 20% (w/v) by metabolising fermentation inhibitors
Comparison of case note review methods for evaluating quality and safety in health care
Objectives: To determine which of two methods of case note review – holistic (implicit) and criterion-based (explicit) – provides the most useful and reliable information for quality and safety of care, and the level of agreement within and between groups of health-care professionals when they use the two methods to review the same record. To explore the process–outcome relationship between holistic and criterion-based quality-of-care measures and hospital-level outcome indicators. © 2010 Crown Copyrigh
An Analytic Variational Study of the Mass Spectrum in 2+1 Dimensional SU(3) Hamiltonian Lattice Gauge Theory
We calculate the masses of the lowest lying eigenstates of improved SU(2) and
SU(3) lattice gauge theory in 2+1 dimensions using an analytic variational
approach. The ground state is approximated by a one plaquette trial state and
mass gaps are calculated in the symmetric and antisymmetric sectors by
minimising over a suitable basis of rectangular states
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