2,695 research outputs found
Suggested hurricane operational scenario for GOES I-M
Improvements in tropical cyclone forecasts require optimum use of remote sensing capabilities, because conventional data sources cannot provide the necessary spatial and temporal data density over tropical and subtropical oceanic regions. In 1989, the first of a series of geostationary weather satellites, GOES 1-M, will be launched with the capability for simultaneous imaging and sounding. Careful scheduling of the GOES 1-M will enable measurements of both the wind and mass fields over the entire tropical cyclone activity area. The document briefly describes the GOES 1-M imager and sounder, surveys the data needs for hurricane forecasting, discusses how geostationary satellite observations help to meet them, and proposes a GOES 1-M schedule of observations and hurricane relevant derived products
Dual-path state reconstruction scheme for propagating quantum microwaves and detector noise tomography
Quantum state reconstruction involves measurement devices that are usually
described by idealized models, but not known in full detail in experiments. For
weak propagating microwaves, the detection process requires linear amplifiers
which obscure the signal with random noise. Here, we introduce a theory which
nevertheless allows one to use these devices for measuring all quadrature
moments of propagating quantum microwaves based on cross-correlations from a
dual-path amplification setup. Simultaneously, the detector noise properties
are determined, allowing for tomography. We demonstrate the feasibility of our
novel concept by proof-of-principle experiments with classical mixtures of weak
coherent microwaves.Comment: 11 pages, 3 figure
Tunable and Switchable Coupling Between Two Superconducting Resonators
We realize a device allowing for tunable and switchable coupling between two
superconducting resonators mediated by an artificial atom. For the latter, we
utilize a persistent current flux qubit. We characterize the tunable and
switchable coupling in frequency and time domain and find that the coupling
between the relevant modes can be varied in a controlled way. Specifically, the
coupling can be tuned by adjusting the flux through the qubit loop or by
saturating the qubit. Our time domain measurements allow us to find parameter
regimes for optimal switch performance with respect to qubit drive power and
the dynamic range of the resonator input power
A simple and versatile analytical approach for planar metamaterials
We present an analytical model which permits the calculation of effective
material parameters for planar metamaterials consisting of arbitrary unit cells
(metaatoms) formed by a set of straight wire sections of potentially different
shape. The model takes advantage of resonant electric dipole oscillations in
the wires and their mutual coupling. The pertinent form of the metaatom
determines the actual coupling features. This procedure represents a kind of
building block model for quite different metaatoms. Based on the parameters
describing the individual dipole oscillations and their mutual coupling the
entire effective metamaterial tensor can be determined. By knowing these
parameters for a certain metaatom it can be systematically modified to create
the desired features. Performing such modifications effective material
properties as well as the far field intensities remain predictable. As an
example the model is applied to reveal the occurrence of optical activity if
the split ring resonator metaatom is modified to L- or S-shaped metaatoms.Comment: 5 figures, 1 tabl
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