14,285 research outputs found

    Restoration of multichannel microwave radiometric images

    Get PDF
    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

    Full text link
    We describe a novel scheme to implement scalable quantum information processing using Li-Cs molecular state to entangle 6^{6}Li and 133^{133}Cs ultracold atoms held in independent optical lattices. The 6^{6}Li atoms will act as quantum bits to store information, and 133^{133}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

    Get PDF
    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

    Get PDF
    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

    Get PDF
    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

    Full text link
    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

    Full text link
    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

    Full text link
    We study collective excitation modes of a fermionic gas of 6^6Li 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
    corecore