557 research outputs found
Rating of Mixed Split Residential Air Conditioners
A methodology is presented for rating the performance
of mixed, split residential air conditioners.
The method accounts for the impact on system
performance of the indoor evaporator, expansion
device and fan; three major components that are
likely to be substituted for the matched components
in a mixed system. The method allows calculation of
capacity at 95°F rating point and seasonal energy
efficiency ratio, SEER, without performing laboratory
test of the complete system. Limitations of
the procedure, present work, and anticipated
improvements are also discussed
Simple theory of extremely overdoped HTS
We demonstrate the existence of a simple physical picture of
superconductivity for extremely overdoped CuO2 planes. It possesses all
characteristic features of HTS, such as a high superconducting transition
temperature, the symmetry of order parameter, and the
coexistence of a single electron Fermi surface and a pseudogap in the normal
state. Values of pseudogap are calculated for different doping levels. An
orbital paramagnetism of preformed pairs is predicted.Comment: 7 pages, 1 figur
A Pixel Vertex Tracker for the TESLA Detector
In order to fully exploit the physics potential of a e+e- linear collider,
such as TESLA, a Vertex Tracker providing high resolution track reconstruction
is required. Hybrid Silicon pixel sensors are an attractive sensor technology
option due to their read-out speed and radiation hardness, favoured in the high
rate TESLA environment, but have been so far limited by the achievable single
point space resolution. A novel layout of pixel detectors with interleaved
cells to improve their spatial resolution is introduced and the results of the
characterisation of a first set of test structures are discussed. In this note,
a conceptual design of the TESLA Vertex Tracker, based on hybrid pixel sensors
is presentedComment: 20 pages, 11 figure
Metal-insulator crossover in the Boson-Fermion model in infinite dimensions
The Boson-Fermion model, describing a mixture of tightly bound electron pairs
and quasi-free electrons hybridized with each other via a charge exchange term,
is studied in the limit of infinite dimensions, using the Non-Crossing
Approximation within the Dynamical Mean Field Theory. It is shown that a
metal-insulator crossover, driven by strong pair fluctuations, takes place as
the temperature is lowered. It manifests itself in the opening of a pseudogap
in the electron density of states, accompanied by a corresponding effect in the
optical and dc conductivity.Comment: 4 pages, 3 figures, to be published in Phys. Rev. Let
Non-linear feedback effects in coupled Boson-Fermion systems
We address ourselves to a class of systems composed of two coupled subsystems
without any intra-subsystem interaction: itinerant Fermions and localized
Bosons on a lattice. Switching on an interaction between the two subsystems
leads to feedback effects which result in a rich dynamical structure in both of
them. Such feedback features are studied on the basis of the flow equation
technique - an infinite series of infinitesimal unitary transformations - which
leads to a gradual elimination of the inter-subsystem interaction. As a result
the two subsystems get decoupled but their renormalized kinetic energies become
mutually dependent on each other. Choosing for the inter - subsystem
interaction a charge exchange term (the Boson-Fermion model) the initially
localized Bosons acquire itinerancy through their dependence on the
renormalized Fermion dispersion. This latter evolves from a free particle
dispersion into one showing a pseudogap structure near the chemical potential.
Upon lowering the temperature both subsystems simultaneously enter a
macroscopic coherent quantum state. The Bosons become superfluid, exhibiting a
soundwave like dispersion while the Fermions develop a true gap in their
dispersion. The essential physical features described by this technique are
already contained in the renormalization of the kinetic terms in the respective
Hamiltonians of the two subsystems. The extra interaction terms resulting in
the process of iteration only strengthen this physics. We compare the results
with previous calculations based on selfconsistent perturbative approaches.Comment: 14 pages, 16 figures, accepted for publication in Phys. Rev.
MASCOT : metadata for advanced scalable video coding tools : final report
The goal of the MASCOT project was to develop new video coding schemes and tools that provide both an increased coding efficiency as well as extended scalability features compared to technology that was available at the beginning of the project. Towards that goal the following tools would be used: - metadata-based coding tools; - new spatiotemporal decompositions; - new prediction schemes. Although the initial goal was to develop one single codec architecture that was able to combine all new coding tools that were foreseen when the project was formulated, it became clear that this would limit the selection of the new tools. Therefore the consortium decided to develop two codec frameworks within the project, a standard hybrid DCT-based codec and a 3D wavelet-based codec, which together are able to accommodate all tools developed during the course of the project
Hole-mediated photoredox catalysis: Tris(: P-substituted)biarylaminium radical cations as tunable, precomplexing and potent photooxidants
As a combination of visible light photoredox catalysis and synthetic organic electrochemistry, electrochemically-mediated photoredox catalysis emerged as a powerful synthetic technique in recent years, overcoming fundamental limitations of electrochemistry and photoredox catalysis in the single electron transfer activation of small organic molecules. Herein we report a tunable class of electroactivated photoredox catalyst, tri(para-substituted)biarylamines, that become superoxidants in their photoexcited states even able to oxidize molecules beyond the solvent window limits of cyclic voltammetry (such as polyfluorobenzene and trifluorotoluene). Furthermore, we demonstrate that precomplexation not only permits the excited state photochemistry of tris(para-substituted)biarylaminium cations to overcome picosecond lifetime, but enables and rationalizes the surprising photochemistry of their higher-order doublet (Dn) excited states, unlocking extremely high oxidative potentials (up to a record-breaking ∼+4.4 V vs. SCE). This journal i
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