897 research outputs found

    A case study of the influences of audience and purpose on the composing processes of an engineer

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    The design and preliminary findings of a study of composing processes (on the job) of engineers, managers, and scientists is presented. The influences of audience and purpose on the composing process of engineers was of concern; specifically, the cognitive processes, physical behaviors, and factors that influence the evoluton of a piece of writing. An overview of the study, related literature, outlines of research design, and preliminary findings from a case study of engineers are given. It is suggested that teaching be adapted to help students learn to represent rhetorical problems to guide composing for effective writing

    An electrochemical rebalance cell for Redox systems

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    An electrochemical rebalance cell for maintaining electrochemical balance, at the system level, of the acidified aqueous iron chloride and chromium chloride reactant solutions in the redox energy storage system was constructed and evaluated. The electrochemical reaction for the cathode is Fe(+3) + e(-) yields Fe(+2), and that for the anode is 1/2H2 yields H(+) + e(-). The iron (carbon felt) electrode and the hydrogen (platinized carbon) electrode are separated by an anion exchange membrane. The performance of the rebalance cell is discussed as well as the assembly of a single rebalance cell and multicell stacks. Various cell configurations were tested and the results are presented and discussed. The rebalance cell was also used to demonstrate its ability, as a preparative tool, for making high purity solutions of soluble reduced metal ionic species. Preparations of titanium, copper, vanadium and chromium ions in acidified solutions were evaluated

    Hyperbolic/parabolic development for the GIM-STAR code

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    Flow fields in supersonic inlet configurations were computed using the eliptic GIM code on the STAR computer. Spillage flow under the lower cowl was calculated to be 33% of the incoming stream. The shock/boundary layer interaction on the upper propulsive surface was computed including separation. All shocks produced by the flow system were captured. Linearized block implicit (LBI) schemes were examined to determine their application to the GIM code. Pure explicit methods have stability limitations and fully implicit schemes are inherently inefficient; however, LBI schemes show promise as an effective compromise. A quasiparabolic version of the GIM code was developed using elastical parabolized Navier-Stokes methods combined with quasitime relaxation. This scheme is referred to as quasiparabolic although it applies equally well to hyperbolic supersonic inviscid flows. Second order windward differences are used in the marching coordinate and either explicit or linear block implicit time relaxation can be incorporated

    Development of the general interpolants method for the CYBER 200 series of supercomputers

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    The General Interpolants Method (GIM) is a 3-D, time-dependent, hybrid procedure for generating numerical analogs of the conservation laws. This study is directed toward the development and application of the GIM computer code for fluid dynamic research applications as implemented for the Cyber 200 series of supercomputers. An elliptic and quasi-parabolic version of the GIM code are discussed. Turbulence models, algebraic and differential equations, were added to the basic viscous code. An equilibrium reacting chemistry model and an implicit finite difference scheme are also included

    Magnetoelectric Jones Dichroism in Atoms

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    The authors suggest that atomic experiments measuring the interference between magnetic-dipole and electric-field-induced electric-dipole transition amplitudes provide a valuable system to study magnetoelectric Jones effects.Comment: 3 pages, 2 figure

    Measurement of excited-state transitions in cold calcium atoms by direct femtosecond frequency-comb spectroscopy

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    We apply direct frequency-comb spectroscopy, in combination with precision cw spectroscopy, to measure the 4s4p3P14s5s3S1{\rm 4s4p} ^3P_1 \to {\rm 4s5s} ^3S_1 transition frequency in cold calcium atoms. A 657 nm ultrastable cw laser was used to excite atoms on the narrow (γ400\gamma \sim 400 Hz) 4s21S04s4p3P1{\rm 4s^2} ^1S_0 \to {\rm 4s4p} ^3P_1 clock transition, and the direct output of the frequency comb was used to excite those atoms from the 4s4p3P1{\rm 4s4p} ^3P_1 state to the 4s5s3S1{\rm 4s5s} ^3S_1 state. The resonance of this second stage was detected by observing a decrease in population of the ground state as a result of atoms being optically pumped to the metastable 4s4p3P0,2{\rm 4s4p} ^3P_{0,2} states. The 4s4p3P14s5s3S1{\rm 4s4p} ^3P_1 \to {\rm 4s5s} ^3S_1 transition frequency is measured to be ν=489544285713(56)\nu = 489 544 285 713(56) kHz; which is an improvement by almost four orders of magnitude over the previously measured value. In addition, we demonstrate spectroscopy on magnetically trapped atoms in the 4s4p3P2{\rm 4s4p} ^3P_2 state.Comment: 4 pages 5 figure

    Safety, the Preface Paradox and Possible Worlds Semantics

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    This paper contains an argument to the effect that possible worlds semantics renders semantic knowledge impossible, no matter what ontological interpretation is given to possible worlds. The essential contention made is that possible worlds semantic knowledge is unsafe and this is shown by a parallel with the preface paradox

    AC Stark shift noise in QND measurement arising from quantum fluctuations of light polarization

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    In a recent letter [Auzinsh {\it{et. al.}} (physics/0403097)] we have analyzed the noise properties of an idealized atomic magnetometer that utilizes spin squeezing induced by a continuous quantum nondemolition measurement. Such a magnetometer measures spin precession of NN atomic spins by detecting optical rotation of far-detuned probe light. Here we consider maximally squeezed probe light, and carry out a detailed derivation of the contribution to the noise in a magnetometric measurement due to the differential AC Stark shift between Zeeman sublevels arising from quantum fluctuations of the probe polarization.Comment: This is a companion note to physics/040309

    Electric Fields and Calcium Mobility in Bone Final Report

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    Effect of electric fields on calcium mobility of bon
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