16,898 research outputs found
Comparison of combustion efficiencies for ramjet engines
Four different combustion efficiencies commonly used for assessing ramjet engines are compared. The mixture ratios cover a range from stoichiometric to an equivalence ratio of 0.2, and the polyethylene/air propellant system is used. The ratio of effective to ideal temperature rise is taken as reference efficiency. As might be expected, major differences can be observed near stoichiometric and down to equilvalence ratios of 0.5. These are quantitatively demonstrated
Delta-Interference of Two Friedel Resonances
When a single resonator is coupled to a continuous spectrum one obtains a
resonance of finite half-width. Such a resonance is known in many fields of
physics. The Friedel resonance is an example where a d-impurity is dissolved in
a simple metal. If two resonators are coupled to the continuous spectrum the
resonances interfere. For identical coupling and frequencies one obtains two
effective resonances. The effective coupling of one of them to the continuum
can be tuned to zero yielding a delta-like resonance
REGIONAL IMPACT ANALYSIS OF EUROPEAN POLICY SPENDING IN A RURAL REMOTE AREA (CAITHNESS & SUTHERLAND, SCOTLAND, UK)
A modified version of a system dynamics model constructed for an EU-wide case-study project (TOP-MARD) using STELLA software was used to simulate the effects of a number of development scenarios for a remote rural area in Northern Scotland, i.e. Caithness & Sutherland, which is characterised by a high regional importance of agriculture for the local economy. In this paper, the context of the modelling work in policy and socio-economic terms is first described. This is followed by the specification of the model and of the several modelling scenarios, which relate to the reconfiguration of Pillar 2 spending within the area and an reversal of recent Structural Funds spending for 2007 onwards. The modelling results are discussed, in terms of regional population and economic trends, from 2001 to 2015. Finally, some conclusions are drawn, both about the implications of the results for such remote rural regions, and about the usefulness of this type of modelling exercise for policy analysis of rural development measures.modelling, input-output, systems dynamics, rural viability, Marketing,
Modelling Policies for Multifunctional Agriculture and Rural Development in a Remote EU Region (Caithness & Sutherland, Scotland, UK)
A modified version of a system dynamics model constructed for an EU-wide case-study project (TOPMARD) using STELLA software was used to simulate the effects of a number of development scenarios for a remote rural area in Northern Scotland, i.e. Caithness & Sutherland, which is characterised by multifunctional agriculture. In this paper, the context of the modelling work in policy and socioeconomic terms is first described. This is followed by the specification of the model and of the modelling scenarios, one of which relates to the âdecommissioningâ (run-down) of a major industrial site (Dounreay) within the area. The modelling results are discussed, in terms of regional population, land use, economic and other terms, from 2001 to 2015/2031. Finally, some conclusions are drawn, both about the implications of the results for such remote rural regions, and the usefulness of this type of modelling exercise for policy analysis of multifunctionality and rural development.modelling, multifunctionality, input-output, systems dynamics, rural policy, Agricultural and Food Policy, Community/Rural/Urban Development, Public Economics, Research Methods/ Statistical Methods,
REGIONAL DEVELOPMENT OPTIONS ON A LOCAL SCALE BEYOND 2013 â THE CASE OF CAITHNESS AND SUTHERLAND (SCOTLAND, UK)
With the latest reform of EU Structural Policy, the Highlands and Islands have been excluded from further support by Structural Funds beyond 2013, but the new Scottish Rural Development Programme has increased CAP Pillar 2 expenditures in Scotland. A modified version of a system dynamics model constructed for an EU-wide case-study project (TOP-MARD) was used to simulate the effects of these and other policy changes in Caithness and Sutherland (C&S), a remote rural area in Northern Scotland. Several alternative modelling scenarios were developed, mostly relating to reconfigurations of Pillar 2 spending within the area. The modelling results, i.e. projections from 2001 to 2021, are discussed in terms of agricultural employment, regional population, and economic trends. It is shown that by targeting Pillar 2 money to non-agricultural rural development measures instead of to farm investments, less favoured area or agrienvironmental schemes, the long-term trends in severe depopulation, ageing and deindustrialisation in the area can be alleviated but not avoided. Finally, some conclusions are drawn, both about the implications of the results for sustainability in C&S, and in general for future sustainable rural development policy.rural development, CAP reform, Scotland, Pillar 2, regional modelling, Community/Rural/Urban Development, Q01, Q18, R23, R50,
The Physical Role of Gravitational and Gauge Degrees of Freedom in General Relativity - II: Dirac versus Bergmann observables and the Objectivity of Space-Time
(abridged)The achievements of the present work include: a) A clarification of
the multiple definition given by Bergmann of the concept of {\it (Bergmann)
observable. This clarification leads to the proposal of a {\it main conjecture}
asserting the existence of i) special Dirac's observables which are also
Bergmann's observables, ii) gauge variables that are coordinate independent
(namely they behave like the tetradic scalar fields of the Newman-Penrose
formalism). b) The analysis of the so-called {\it Hole} phenomenology in strict
connection with the Hamiltonian treatment of the initial value problem in
metric gravity for the class of Christoudoulou -Klainermann space-times, in
which the temporal evolution is ruled by the {\it weak} ADM energy. It is
crucial the re-interpretation of {\it active} diffeomorphisms as {\it passive
and metric-dependent} dynamical symmetries of Einstein's equations, a
re-interpretation which enables to disclose their (nearly unknown) connection
to gauge transformations on-shell; this is expounded in the first paper
(gr-qc/0403081). The use of the Bergmann-Komar {\it intrinsic
pseudo-coordinates} allows to construct a {\it physical atlas} of 4-coordinate
systems for the 4-dimensional {\it mathematical} manifold, in terms of the
highly non-local degrees of freedom of the gravitational field (its four
independent {\it Dirac observables}), and to realize the {\it physical
individuation} of the points of space-time as {\it point-events} as a
gauge-fixing problem, also associating a non-commutative structure to each
4-coordinate system.Comment: 41 pages, Revtex
Systematics of Large Axial Vector Meson Production in Heavy Flavor Weak Decays
Branching ratios observed for and B decays to final states
are comparable to those for corresponding decays to
and and much larger than those for all other
decays. Implications are discussed of a "vector-dominance model" in which a
is produced and immediately turns into an axial vector, vector or pseudoscalar
meson. Data for decays to all such final states are shown to have large
branching ratios and satisfy universality relations. Upper limits on small
strong phase differences between amplitudes relevant to CP violation models are
obtained from analysis of the predicted and observed suppression of
decays into neutral final states , and . .
Branching ratios of are predicted for the as yet unobserved
presence of the charmed-strange axial vector in B decays.Comment: 14 page
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