2,319 research outputs found

    A precisely controlled, low range humidity system

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    Development of environmental control system for determining effects of relative humidity and dry heat on inactivation of microorganism

    Numerical Study of Wave Propagation in Uniaxially Anisotropic Lorentzian Backward Wave Slabs

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    The propagation and refraction of a cylindrical wave created by a line current through a slab of backward wave medium, also called left-handed medium, is numerically studied with FDTD. The slab is assumed to be uniaxially anisotropic. Several sets of constitutive parameters are considered and comparisons with theoretical results are made. Electric field distributions are studied inside and behind the slab. It is found that the shape of the wavefronts and the regions of real and complex wave vectors are in agreement with theoretical results.Comment: 6 pages, figure

    Tunneling of Cooper pairs across voltage biased asymmetric single-Cooper-pair transistors

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    We analyze tunneling of Cooper pairs across voltage biased asymmetric single-Cooper-pair transistors. Also tunneling of Cooper pairs across two capacitively coupled Cooper-pair boxes is considered, when the capacitive coupling and Cooper pair tunneling are provided by a small Josephson junction between the islands. The theoretical analysis is done at subgap voltages, where the current-voltage characteristics depend strongly on the macroscopic eigenstates of the island(s) and their coupling to the dissipative environment. As the environment we use an impedance which satisfies Re[Z]<<R_Q and a few LC-oscillators in series with Z. The numerically calculated I-V curves are compared with experiments where the quantum states of mesoscopic SQUIDs are probed with inelastic Cooper pair tunneling. The main features of the observed I-V data are reproduced. Especially, we find traces of band structure in the higher excited states of the Cooper-pair boxes as well as traces of multiphoton processes between two Cooper-pair boxes in the regime of large Josephson coupling.Comment: 9 pages, 9 figures, Revtex

    Thermoradiation inactivation of naturally occurring organisms in soil

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    Samples of soil collected from Kennedy Space Center near spacecraft assembly facilities were found to contain microorganisms very resistant to conventional sterilization techniques. The inactivation behavior of the naturally occurring spores in soil was investigated using dry heat and ionizing radiation, first separately, then in combination. Dry heat inactivation rates of spores were determined for 105 and 125 C. Radiation inactivation rates were determined for dose rates of 660 and 76 krad/hr at 25 C. Simultaneous combinations of heat and radiation were then investigated at 105, 110, 115, 120, and 125 C. Combined treatment was found to be highly synergistic requiring greatly reduced radiation doses to accomplish sterilization

    Design requirements for laminar airflow clean rooms and devices

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    Laminar airflow and airborne contamination control concepts with clean room specifications and laminar flow facility design

    Effect of the shot-noise on a Coulomb blockaded single Josephson junction

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    We have investigated how the Coulomb blockade of a mesoscopic Josephson junction in a high-impedance environment is suppressed by shot noise from an adjacent junction. The presented theoretical analysis is an extension of the phase correlation theory for the case of a non-Gaussian noise. Asymmetry of the non-Gaussian noise should result in the shift of the conductance minimum from zero voltage and the ratchet effect (nonzero current at zero voltage), which have been experimentally observed. The analysis demonstrates that a Coulomb blockaded tunnel junction in a high impedance environment can be used as an effective noise detector.Comment: 4 pages, 1 figure; figure and typos corrected, added reference

    Visualizing Uncertainty in Predicted Hurricane Tracks

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    Although the past 30 years have seen major advances in the scientific understanding of hurricane forecasting, there has been a lack of systematic research on people’s comprehension of displays used to show these forecasts. A primary visual aids is the error cone. The center line represents the predicted hurricane track for a five day period. The width of the cone is determined by considering historical forecast errors over a five year sample, and represents a 67% likelihood region for the hurricane track. A primary challenge of this model is that that most people have difficulty in understanding the probabilistic concepts that are used to communicate uncertainty. For example, it tends to give the impression to those inside the cone that they have an exaggerated chance of being in the hurricane\u27s path, while those outside of the cone tend to feel a false sense of security. We have developed a new method of visualizing the possible projected paths of hurricanes using the projected path of a given hurricane as well as the historical data of previous hurricanes. The goal is to maintain a display that shows a range of possible outcomes, while maintaining the statistical characteristics of the error cone

    A modified SST k-? turbulence model to predict the steady and unsteady sheet cavitation on 2D and 3D hydrofoils

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    The paper presents a study of using a modified SST (Shear-Stress Transport) k-? model with a multi-phase mixture flow RANS solver to predict the steady and unsteady cavitating flows around 2D and 3D hydrofoils. Based on Reboud et al [6] s idea of modifying turbulent viscosity for a RNG k-­ model, a modification is applied to a SST k-? model in the present work. The cavitation is modeled by Schnerr-Sauer s cavitation model [16]. First, results of 2D NACA0015 foil at two cavitation numbers, ? =1.6 (stable sheet cavitation) and ?=1.0 (unsteady with shedding) are compared for different grids and with available experiment data. Then, the problem of the standard SST model in predicting unsteady cavitation is discussed. Finally the results for a 3D twisted hydrofoil are compared with the experiment by Foeth and Terwisga [3]. It is found that with the modified SST k-? model the RANS solver is able to predict the essential features like development of re-entrant jets, the pinch-off, the shedding of vortex and cloud cavities for the 2D NACA0015 foil at ? =1.0. For the case at ? =1.6, the model predicts a high frequency fluctuating sheet cavity with minor shedding at its closure. Compared with the standard SST model, the global quantities like lift, drag, and shedding frequency predicted by the modified model are closer to the experimental data, although considerable discrepancy with the experiment data is noted for the unsteady case at ? =1.0. In addition, a special type of secondary cavities, developed downstream an upstream-moving collapse cavity and termed as vortex group cavitation by Bark et al [1], appears to be observable in the simulation at this condition. The existence of this type of cavity has been reconfirmed in a recent experiment in the SSPA s cavitation tunnel.http://deepblue.lib.umich.edu/bitstream/2027.42/84288/1/CAV2009-final107.pd

    ESTATE PLANNING IN NORTH DAKOTA: THE BASICS Part 4: Trusts

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    Formerly published under the HE seriesFE-554 (Revised
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