820 research outputs found

    Viking orbiter stereo imaging catalog

    Get PDF
    The extremely long missions of the two Viking Orbiter spacecraft produced a wealth of photos of surface features. Many of which can be used to form stereo images allowing the earth-bound student of Mars to examine the subject in 3-D. This catalog is a technical guide to the use of stereo coverage within the complex Viking imaging data set. Since that data set is still growing (January, 1980, about 3 1/2 years after the mission began), a second edition of this catalog is planned with completion expected about November, 1980

    Optical read out and feedback cooling of a nanostring optomechanical cavity

    Get PDF
    Optical measurement of the motion of a 940 kHz mechanical resonance of a silicon nitride nanostring resonator is demonstrated with a read out noise imprecision reaching 37 dB below that of the resonator's zero-point fluctuations. Via intensity modulation of the optical probe laser, radiation pressure feedback is used to cool and damp the mechanical mode from an initial room temperature occupancy of nˉb=6.5×106\bar{n}_{b} = 6.5 \times 10^6 (Tb=295T_{b}=295K) down to a phonon occupation of n=66±10\langle n \rangle = 66 \pm 10, representing a mode temperature of Tm3T_{m} \approx 3mK. The five decades of cooling is enabled by the system's large single-photon cooperativity (C1=4)(C_{1} = 4) and high quantum efficiency of optical motion detection (ηt=0.27\eta_{t} = 0.27).Comment: 13 pages, 13 figure

    Geology orbiter comparison study

    Get PDF
    Instrument requirements of planetary geology orbiters were examined with the objective of determining the feasibility of applying standard instrument designs to a host of terrestrial targets. Within the basic discipline area of geochemistry, gamma-ray, X-ray fluorescence, and atomic spectroscopy remote sensing techniques were considered. Within the discipline area of geophysics, the complementary techniques of gravimetry and radar were studied. Experiments using these techniques were analyzed for comparison at the Moon, Mercury, Mars and the Galilean satellites. On the basis of these comparative assessments, the adaptability of each sensing technique was judged as a basic technique for many targets, as a single instrument applied to many targets, as a single instrument used in different mission modes, and as an instrument capability for nongeoscience objectives

    Viking orbiter stereo imaging catalog

    Get PDF
    The extremely long mission of the two Viking Orbiter spacecraft produced a wealth of photos of surface features. Many of these photos can be used to form stereo images allowing the student of Mars to examine a subject in three dimensional. This catalog is a technical guide to the use of stereo coverage within the complex Viking imaging data set

    The Influence of Application System Quality Control in the Performance of Auditors (Empirical Studies) ABC Kap in South Jakarta in 2009 – 2013

    Full text link
    This study has the objective to determine the effect the independence, professionalism, professional ethics and integrity of client understanding of the performance of the auditors on an empirical study of the public accounting firm ABC in South Jakarta. The method used in sampling is convenience sampling. The number of questionnaires distributed 150 questionnaires. However, the back and can be used for further analysis of 120 questionnaires. Analysis of the data is to use multiple linear regression coefficient of determination see, the value of F statistics and statistical t. Results of this study showed that the independence, professionalism and ethics of the profession positive effect on the performance of auditors while understanding client integrity negative effect on the performance of auditors

    Chaos induced coherence in two independent food chains

    Full text link
    Coherence evolution of two food web models can be obtained under the stirring effect of chaotic advection. Each food web model sustains a three--level trophic system composed of interacting predators, consumers and vegetation. These populations compete for a common limiting resource in open flows with chaotic advection dynamics. Here we show that two species (the top--predators) of different colonies chaotically advected by a jet--like flow can synchronize their evolution even without migration interaction. The evolution is charaterized as a phase synchronization. The phase differences (determined through the Hilbert transform) of the variables representing those species show a coherent evolution.Comment: 5 pages, 5 eps figures. Accepted for publication in Phys. Rev.

    Coexistence of ferromagnetism and superconductivity in the hybrid ruthenate-cuprate compound RuSr_2GdCu_2O_8 studied by muon spin rotation (\mu SR) and DC-magnetization

    Full text link
    We have investigated the magnetic and the superconducting properties of the hybrid ruthenate-cuprate compound RuSr_{2}GdCu_{2}O_{8} by means of zero-field muon spin rotation- (ZF-μ\mu SR) and DC magnetization measurements. The DC-magnetisation data establish that this material exhibits ferromagnetic order of the Ru-moments (μ(Ru)1μB\mu (Ru) \approx 1 \mu_{B}) below T_{Curie} = 133 K and becomes superconducting at a much lower temperature T_c = 16 K. The ZF-μ\mu SR experiments indicate that the ferromagnetic phase is homogeneous on a microscopic scale and accounts for most of the sample volume. They also suggest that the magnetic order is not significantly modified at the onset of superconductivity.Comment: improved version submitted to Phys. Rev.

    Boundary layer structure in turbulent thermal convection and its consequences for the required numerical resolution

    Get PDF
    Results on the Prandtl-Blasius type kinetic and thermal boundary layer thicknesses in turbulent Rayleigh-B\'enard convection in a broad range of Prandtl numbers are presented. By solving the laminar Prandtl-Blasius boundary layer equations, we calculate the ratio of the thermal and kinetic boundary layer thicknesses, which depends on the Prandtl number Pr only. It is approximated as 0.588Pr1/20.588Pr^{-1/2} for PrPrPr\ll Pr^* and as 0.982Pr1/30.982 Pr^{-1/3} for PrPrPr^*\ll\Pr, with Pr=0.046Pr^*= 0.046. Comparison of the Prandtl--Blasius velocity boundary layer thickness with that evaluated in the direct numerical simulations by Stevens, Verzicco, and Lohse (J. Fluid Mech. 643, 495 (2010)) gives very good agreement. Based on the Prandtl--Blasius type considerations, we derive a lower-bound estimate for the minimum number of the computational mesh nodes, required to conduct accurate numerical simulations of moderately high (boundary layer dominated) turbulent Rayleigh-B\'enard convection, in the thermal and kinetic boundary layers close to bottom and top plates. It is shown that the number of required nodes within each boundary layer depends on Nu and Pr and grows with the Rayleigh number Ra not slower than \sim\Ra^{0.15}. This estimate agrees excellently with empirical results, which were based on the convergence of the Nusselt number in numerical simulations

    Zipf law in the popularity distribution of chess openings

    Full text link
    We perform a quantitative analysis of extensive chess databases and show that the frequencies of opening moves are distributed according to a power-law with an exponent that increases linearly with the game depth, whereas the pooled distribution of all opening weights follows Zipf's law with universal exponent. We propose a simple stochastic process that is able to capture the observed playing statistics and show that the Zipf law arises from the self-similar nature of the game tree of chess. Thus, in the case of hierarchical fragmentation the scaling is truly universal and independent of a particular generating mechanism. Our findings are of relevance in general processes with composite decisions.Comment: 5 pages, 4 figure
    corecore