13,811 research outputs found

    Study of optimum discrete estimators in measurement analysis

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    Study of statistical techniques for obtaining estimates of true data parameters uses discrete measured quantities containing random error. These techniques develop estimation procedures as an iterative algorithm for digital computation in real time

    Methods for injection error analysis and their comparison Scientific report no. 13

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    Formulation of direct and adjoint methods of trajectory injection error in vector matrix notation and compariso

    Optimum correction of thrust transient measurements

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    Optimum correction of distorted thrust transient measurement

    Characteristics and performance of the variable polarity plasma arc welding process used in the Space Shuttle external tank

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    Significant advantages of the Variable Polarity Plasma Arc (VPPA) Welding Process include faster welding, fewer repairs, less joint preparation, reduced weldment distortion, and absence of porosity. Flow profiles and power distribution of argon plasma gas as a working fluid to produce plasma arc jet in the VPPA welding process was analyzed. Major loss of heat transfer for flow through the nozzle is convective heat transfer; for the plasma jet flow between the outlet of the nozzle and workpiece is radiative heat transfer; and for the flow through the keyhole of the workpiece is convective heat transfer. The majority of the power absorbed by the keyhole of the workpiece is used for melting the solid metal workpiece into a molten metallic puddle. The crown and root widths and the crown and root heights can be predicted. An algorithm for promoting automatic control of flow parameters and the dimensions of the final product of the welding specification to be used for the VPPA Welding System operated at MSFC are provided

    Geometrical interpretation and graphical solution to minimum energy discrete-data control Scientific report no. 9

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    Linear PAM regulator minimum energy design by geometric interpretation and graphical solutio

    Quantum Spin Dynamics with Pairwise-Tunable, Long-Range Interactions

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    We present a platform for the simulation of quantum magnetism with full control of interactions between pairs of spins at arbitrary distances in one- and two-dimensional lattices. In our scheme, two internal atomic states represent a pseudo-spin for atoms trapped within a photonic crystal waveguide (PCW). With the atomic transition frequency aligned inside a band gap of the PCW, virtual photons mediate coherent spin-spin interactions between lattice sites. To obtain full control of interaction coefficients at arbitrary atom-atom separations, ground-state energy shifts are introduced as a function of distance across the PCW. In conjunction with auxiliary pump fields, spin-exchange versus atom-atom separation can be engineered with arbitrary magnitude and phase, and arranged to introduce non-trivial Berry phases in the spin lattice, thus opening new avenues for realizing novel topological spin models. We illustrate the broad applicability of our scheme by explicit construction for several well known spin models.Comment: 18 pages, 10 figure

    Mining and Incentive Concession Contracts

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    This paper studies the design of a mining concession contract as a multi-period autoselection problem where production is the depletion of a non renewable resource. As compared to symmetric information, we show that overproduction (resp. underproduction) is optimal in the initial phase (resp. terminal phase ) of the resource extraction program. Also, asymmetric information lengthens the contract duration but reduces the scarcity rent. Finally, when there are several agents competing for contract bid, we show that optimal auctioning could be used to award the concession, assigning the lowest cost agent to carry out the extraction.ADVERSE SELECTION; EXHAUSTIBILITY; OVERPRODUCTION
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