7,091 research outputs found

    Skylab S193 and the analysis of the wind field over the ocean

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    The present status of the program to provide proof of concept for the idea that simultaneously observed radar scattering cross section measurements and passive microwave measurements can be used to determine the winds in the planetary boundary layer over the ocean, is given. The role of S193 in Skylab is providing the final clinching proof that an operational instrument will obtain data of great value to both meteorology and oceanography is described

    Real-time antenna fault diagnosis experiments at DSS 13

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    Experimental results obtained when a previously described fault diagnosis system was run online in real time at the 34-m beam waveguide antenna at Deep Space Station (DSS) 13 are described. Experimental conditions and the quality of results are described. A neural network model and a maximum-likelihood Gaussian classifier are compared with and without a Markov component to model temporal context. At the rate of a state update every 6.4 seconds, over a period of roughly 1 hour, the neural-Markov system had zero errors (incorrect state estimates) while monitoring both faulty and normal operations. The overall results indicate that the neural-Markov combination is the most accurate model and has significant practical potential

    The extrapolation of laboratory and aircraft radar sea return data to spacecraft altitudes

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    Laboratory measurements show that the spectra of capillary waves grow with wind speed over six orders of magnitude. The scatter in the data can be partially understood and predicted from a combination of turbulence theory, radar theory, and the small sample theory of statistical inference. When these results are applied to a prediction of the sea return values to be obtained by S193 on Skylab, it can be shown that the size of the illuminated patch effectively averages out the horizontal scales of gustiness, so that the measurement will correspond to the synoptic scale wind

    THE LAND DIVISION AMENDMENTS TO THE SUBDIVISION CONTROL ACT

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    On January 21, 1997, Governor Engler signed into law 1996 P.A. 591, the Land Division Act. This Act replaced the Subdivision Control Act after 30 years and changed the rules on how land is divided in Michigan. 1997 P.A. 87, effective July 28, 1997, amended the recently created 1996 Land Division Act. While some hailed these as positive changes allowing improved land use, others strongly disagree. This paper is an attempt to alleviate the frustration by providing a history of land division legislation in Michigan because past laws creates an assumed set of rights which are not easily changes. The second focus of the paper is to lessen the confusion level by defining the main points of the law.Land Economics/Use,

    Verification results for the Spectral Ocean Wave Model (SOWM) by means of significant wave height measurements made by the GEOS-3 spacecraft

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    Significant wave heights estimated from the shape of the return pulse wave form of the altimeter on GEOS-3 for forty-four orbit segments obtained during 1975 and 1976 are compared with the significant wave heights specified by the spectral ocean wave model (SOWM), which is the presently operational numerical wave forecasting model at the Fleet Numerical Weather Central. Except for a number of orbit segments with poor agreement and larger errors, the SOWM specifications tended to be biased from 0.5 to 1.0 meters too low and to have RMS errors of 1.0 to 1.4 meters. The much fewer larger errors can be attributed to poor wind data for some parts of the Northern Hemisphere oceans. The bias can be attributed to the somewhat too light winds used to generate the waves in the model. Other sources of error are identified in the equatorial and trade wind areas

    Renormalization Group Study of the Intrinsic Finite Size Effect in 2D Superconductors

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    Vortices in a thin-film superconductor interact logarithmically out to a distance on the order of the two-dimensional (2D) magnetic penetration depth λ\lambda_\perp, at which point the interaction approaches a constant. Thus, because of the finite λ\lambda_\perp, the system exhibits what amounts to an {\it intrinsic} finite size effect. It is not described by the 2D Coulomb gas but rather by the 2D Yukawa gas (2DYG). To study the critical behavior of the 2DYG, we map the 2DYG to the massive sine-Gordon model and then perform a renormalization group study to derive the recursion relations and to verify that λ\lambda_\perp is a relevant parameter. We solve the recursion relations to study important physical quantities for this system including the renormalized stiffness constant and the correlation length. We also address the effect of current on this system to explain why finite size effects are not more prevalent in experiments given that the 2D magnetic penetration depth is a relevant parameter.Comment: 8 pages inRevTex, 5 embedded EPS figure

    Oceanographic and meteorological research based on the data products of SEASAT

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    Reservations were expressed concerning the sum of squares wind recovery algorithm and the power law model function. The SAS sum of squares (SOS) method for recovering winds from backscatter data leads to inconsistent results when V pol and H pol winds are compared. A model function that does not use a power law and that accounts for sea surface temperature is needed and is under study both theoretically and by means of the SASS mode 4 data. Aspects of the determination of winds by means of scatterometry and of the utilization of vector wind data for meteorological forecasts are elaborated. The operational aspect of an intermittent assimilation scheme currently utilized for the specification of the initial value field is considered with focus on quantifying the absolute 12-hour linear displacement error of the movement of low centers

    Effective Action and Phase Structure of Multi-Layer Sine-Gordon Type Models

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    We analyze the effective action and the phase structure of N-layer sine-Gordon type models, generalizing the results obtained for the two-layer sine-Gordon model found in [I. Nandori, S. Nagy, K. Sailer and U. D. Jentschura, Nucl. Phys. B725, 467-492 (2005)]. Besides the obvious field theoretical interest, the layered sine-Gordon model has been used to describe the vortex properties of high transition temperature superconductors, and the extension of the previous analysis to a general N-layer model is necessary for a description of the critical behaviour of vortices in realistic multi-layer systems. The distinction of the Lagrangians in terms of mass eigenvalues is found to be the decisive parameter with respect to the phase structure of the N-layer models, with neighbouring layers being coupled by quadratic terms in the field variables. By a suitable rotation of the field variables, we identify the periodic modes (without explicit mass terms) in the N-layer structure, calculate the effective action and determine their Kosterlitz-Thouless type phase transitions to occur at a coupling parameter \beta^2_{c} = 8 N \pi, where N is the number of layers (or flavours in terms of the multi-flavour Schwinger model).Comment: 15 page

    Does the scatterometer see wind speed or friction velocity?

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    Studies of radar backscatter from the sea surface are referred either to the wind speed, U, or friction velocity, u(sub *). Bragg scattering theory suggests that these variations in backscatter are directly related to the height of the capillary-gravity waves modulated by the larger waves in tilt and by straining of the short wave field. The question then arises as to what characteristic of the wind field is most probably correlated with the wave number spectrum of the capillary-gravity waves. The justification for selecting U as the appropriate meteorological parameter to be associated with backscatter from L-band to Ku-band are reviewed. Both theoretical reasons and experimental evidence are used to demonstrate that the dominant parameter is U/C(lambda) where U is the wind speed at a height of about lambda/2 for waves having a phase speed of C(lambda)

    Essais d'insémination artificielle au Cameroun, à l'aide de semence congelée importée. I. Insémination artificielle de femelles zébus en chaleur naturellement

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    Les auteurs présentent les résultats d'un programme de quatre ans d'insémination artificielle chez les femelles zébus de race locale venues naturellement en chaleur à l'aide de semence congelée de races diverses d'importation. La fécondité moyenne rapportée au nombre de vaches inséminées s'établit à 51 p. 100 en gestations contrôlées et à 47 p. 100 en veaux nés viables. Certaines races se sont montrées plus fécondantes que d'autres. Le prix de revient du veau d'insémination, plus élevé que celui de race locale, varie parfois sensiblement suivant la provenance et la race donneuse. Le recours à l'insémination artificielle à l'aide de semence congelée leur paraît justifié surtout en matière de production laitièr
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