14,285 research outputs found
Restoration of multichannel microwave radiometric images
A constrained iterative image restoration method is applied to multichannel diffraction-limited imagery. This method is based on the Gerchberg-Papoulis algorithm utilizing incomplete information and partial constraints. The procedure is described using the orthogonal projection operators which project onto two prescribed subspaces iteratively. Some of its properties and limitations are also presented. The selection of appropriate constraints was emphasized in a practical application. Multichannel microwave images, each having different spatial resolution, were restored to a common highest resolution to demonstrate the effectiveness of the method. Both noise-free and noisy images were used in this investigation
Ultracold molecules: vehicles to scalable quantum information processing
We describe a novel scheme to implement scalable quantum information
processing using Li-Cs molecular state to entangle Li and Cs
ultracold atoms held in independent optical lattices. The Li atoms will
act as quantum bits to store information, and Cs atoms will serve as
messenger bits that aid in quantum gate operations and mediate entanglement
between distant qubit atoms. Each atomic species is held in a separate optical
lattice and the atoms can be overlapped by translating the lattices with
respect to each other. When the messenger and qubit atoms are overlapped,
targeted single spin operations and entangling operations can be performed by
coupling the atomic states to a molecular state with radio-frequency pulses. By
controlling the frequency and duration of the radio-frequency pulses,
entanglement can either be created or swapped between a qubit messenger pair.
We estimate operation fidelities for entangling two distant qubits and discuss
scalability of this scheme and constraints on the optical lattice lasers
Resolution enhancement of multichannel microwave imagery from the Nimbus-7 SMMR for maritime rainfall analysis
A restoration of the 37, 21, 18, 10.7, and 6.6 GHz satellite imagery from the scanning multichannel microwave radiometer (SMMR) aboard Nimbus-7 to 22.2 km resolution is attempted using a deconvolution method based upon nonlinear programming. The images are deconvolved with and without the aid of prescribed constraints, which force the processed image to abide by partial a priori knowledge of the high-resolution result. The restored microwave imagery may be utilized to examined the distribution of precipitating liquid water in marine rain systems
AGRICULTURAL PRODUCTION CONTRACTS TO REDUCE NITRATE LEACHING: A WHOLE-FARM ANALYSIS
Ten alternative seed corn contract specifications are evaluated with respect to nitrate leaching and profitability for the processor firm (principal) and contracted grower (agent). A whole-farm optimization and feasibility analysis suggest that contract terms can be used to reduce non-point source pollution.Crop Production/Industries,
The Brunei Bay as an Effluent Receiving Waterbody: Observations during the Start-up Period of a Kraft Pulp and Paper Mill
The water quality of Brunei Bay, Malaysia, subsequent to receiving iffluent from a pulp and paper mill,
was monitored. Conventional water quality parameters such as dissolved oxygen, suspended solids, and
biochemical oxygen demand were used as indicators to compare the present status of the bay water quality
with that of the baseline. Generally, data gathered during the first 16 months of the mill operation did not
indicate marked changes in the bay water quality. Levels of suspended solids, total organic carbons, and
1, 1-dichlorodimethyl sulfone in the bay water were used as indicators in the determination of dispersion
pattern of the effluent in the coastal areas of the bay
Permutation sampling in Path Integral Monte Carlo
A simple algorithm is described to sample permutations of identical particles
in Path Integral Monte Carlo (PIMC) simulations of continuum many-body systems.
The sampling strategy illustrated here is fairly general, and can be easily
incorporated in any PIMC implementation based on the staging algorithm.
Although it is similar in spirit to an existing prescription, it differs from
it in some key aspects. It allows one to sample permutations efficiently, even
if long paths (e.g., hundreds, or thousands of slices) are needed. We
illustrate its effectiveness by presenting results of a PIMC calculation of
thermodynamic properties of superfluid Helium-four, in which a very simple
approximation for the high-temperature density matrix was utilized
Fermion Masses and Mixings in GUTs with Non-Canonical U(1)_Y
We discuss fermion masses and mixings in models derived from orbifold GUTs
such that gauge coupling unification is achieved without low energy
supersymmetry by utilizing a non-canonical U(1)_Y. A gauged U(1)_X flavor
symmetry plays an essential role, and the Green-Schwarz mechanism is invoked in
anomaly cancellations. Models containing vector-like particles with masses
close to M_{GUT} are also discussed.Comment: 18 page
Collective excitations of a degenerate gas at the BEC-BCS crossover
We study collective excitation modes of a fermionic gas of Li atoms in
the BEC-BCS crossover regime. While measurements of the axial compression mode
in the cigar-shaped trap close to a Feshbach resonance confirm theoretical
expectations, the radial compression mode shows surprising features. In the
strongly interacting molecular BEC regime we observe a negative frequency shift
with increasing coupling strength. In the regime of a strongly interacting
Fermi gas, an abrupt change in the collective excitation frequency occurs,
which may be a signature for a transition from a superfluid to a collisionless
phase.Comment: Feshbach resonance position updated, few minor change
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