1,344 research outputs found
Enabling low-carbon living in new UK housing developments
Purpose: The purpose of this paper is to describe a tool (the Climate Challenge Tool) that allows house builders to calculate whole life carbon equivalent emissions and costs of various carbon and energy reduction options that can be incorporated into the design of new developments. Design/methodology/approach: The tool covers technical and soft (or lifestyle) measures for reducing carbon production and energy use. Energy used within the home, energy embodied in the building materials, and emissions generated through transport, food consumption and waste treatment are taken into account. The tool has been used to assess the potential and cost-effectiveness of various carbon reduction options for a proposed new housing development in Cambridgeshire. These are compared with carbon emissions from a typical UK household. Findings: The tool demonstrated that carbon emission reductions can be achieved at much lower costs through an approach which enables sustainable lifestyles than through an approach which focuses purely on reducing heat lost through the fabric of the building and from improving the heating and lighting systems. Practical implications: The tool will enable house builders to evaluate which are the most cost-effective measures that they can incorporate into the design of new developments in order to achieve the significant energy savings and reduction in carbon emissions necessary to meet UK Government targets and to avoid dangerous climate change. Originality/value: Current approaches to assessing carbon and energy reduction options for new housing developments concentrate on energy efficiency options such as reducing heat lost through the fabric of the building and improving the heating and lighting systems, alongside renewable energy systems. The Climate Challenge Tool expands the range of options that might be considered by developers to include those affecting lifestyle choices of future residents. © Emerald Group Publishing Limited
Polynomial normal forms of Constrained Differential Equations with three parameters
We study generic constrained differential equations (CDEs) with three
parameters, thereby extending Takens's classification of singularities of such
equations. In this approach, the singularities analyzed are the Swallowtail,
the Hyperbolic, and the Elliptic Umbilics. We provide polynomial local normal
forms of CDEs under topological equivalence. Generic CDEs are important in the
study of slow-fast (SF) systems. Many properties and the characteristic
behavior of the solutions of SF systems can be inferred from the corresponding
CDE. Therefore, the results of this paper show a first approximation of the
flow of generic SF systems with three slow variables.Comment: This is an updated and revised version. Minor modifications mad
Floquet Topological Polaritons in Semiconductor Microcavities
We propose and model Floquet topological polaritons in semiconductor
microcavities, using the interference of frequency detuned coherent fields to
provide a time periodic potential. For arbitrarily weak field strength, where
the Floquet frequency is larger than the relevant bandwidth of the system, a
Chern insulator is obtained. As the field strength is increased, a topological
phase transition is observed with an unpaired Dirac cone proclaiming the
anomalous Floquet topological insulator. As the relevant bandwidth increases
even further, an exotic Chern insulator with flat band is observed with
unpaired Dirac cone at the second critical point. Considering the polariton
spin degree of freedom, we find that the choice of field polarization allows
oppositely polarized polaritons to either co-propagate or counter-propagate in
chiral edge states.Comment: Accepted by PR
Resonances and Twist in Volume-Preserving Mappings
The phase space of an integrable, volume-preserving map with one action and
angles is foliated by a one-parameter family of -dimensional invariant
tori. Perturbations of such a system may lead to chaotic dynamics and
transport. We show that near a rank-one, resonant torus these mappings can be
reduced to volume-preserving "standard maps." These have twist only when the
image of the frequency map crosses the resonance curve transversely. We show
that these maps can be approximated---using averaging theory---by the usual
area-preserving twist or nontwist standard maps. The twist condition
appropriate for the volume-preserving setting is shown to be distinct from the
nondegeneracy condition used in (volume-preserving) KAM theory.Comment: Many typos fixed and notation simplified. New order
averaging theorem and volume-preserving variant. Numerical comparison with
averaging adde
A Cantor set of tori with monodromy near a focus-focus singularity
We write down an asymptotic expression for action coordinates in an
integrable Hamiltonian system with a focus-focus equilibrium. From the
singularity in the actions we deduce that the Arnol'd determinant grows
infinitely large near the pinched torus. Moreover, we prove that it is possible
to globally parametrise the Liouville tori by their frequencies. If one
perturbs this integrable system, then the KAM tori form a Whitney smooth
family: they can be smoothly interpolated by a torus bundle that is
diffeomorphic to the bundle of Liouville tori of the unperturbed integrable
system. As is well-known, this bundle of Liouville tori is not trivial. Our
result implies that the KAM tori have monodromy. In semi-classical quantum
mechanics, quantisation rules select sequences of KAM tori that correspond to
quantum levels. Hence a global labeling of quantum levels by two quantum
numbers is not possible.Comment: 11 pages, 2 figure
Resonances in a spring-pendulum: algorithms for equivariant singularity theory
A spring-pendulum in resonance is a time-independent Hamiltonian model system for formal reduction to one degree of freedom, where some symmetry (reversibility) is maintained. The reduction is handled by equivariant singularity theory with a distinguished parameter, yielding an integrable approximation of the Poincaré map. This makes a concise description of certain bifurcations possible. The computation of reparametrizations from normal form to the actual system is performed by Gröbner basis techniques.
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