10,786 research outputs found

    Non-equilibrium hydrodynamics of a rotating filament

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    The nonlinear dynamics of an elastic filament that is forced to rotate at its base is studied by hydrodynamic simulation techniques; coupling between stretch, bend, twist elasticity and thermal fluctuations is included. The twirling-overwhirling transition is located and found to be strongly discontinuous. For finite bend and twist persistence length, thermal fluctuations lower the threshold rotational frequency, for infinite persistence length the threshold agrees with previous analytical predictions

    Long term changes in cosmic ray diurnal variations observed by ion chambers in Hong Kong and Japan

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    Yearly average solar diurnal variations of cosmic ray ion chamber data are inspected from a view point of the eleven and the 22 year solar activity cycle modulations. Ion chamber data and neutron data from various stations are added. From an inspection of observed data, a simple approximation that the 11 year and the 22 year variations of the solar diurnal variation are along 18-hour and 12-hour axes, respectively is proposed. The 18-hour component of diurnal variation in the 11 year cycle increases toward the solar active years. The 12-hour component is enhanced when the solar general magnetic field is parallel to the rotation vector, and is almost zero for the other state. The transition occurs when the amplitude of the 18-hour component is greater owing to the transition of the field during the maximum phase of solar activity. The 22 year shift is consistent with the drift modulation model in heliosphere

    A nonlinear drift which leads to κ\kappa-generalized distributions

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    We consider a system described by a Fokker-Planck equation with a new type of momentum-dependent drift coefficient which asymptotically decreases as −1/p-1/p for a large momentum pp. It is shown that the steady-state of this system is a κ\kappa-generalized Gaussian distribution, which is a non-Gaussian distribution with a power-law tail.Comment: Submitted to EPJB. 8 pages, 2 figures, dedicated to the proceedings of APFA

    Modal test of the Viking orbiter

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    A modal test of the Orbiter Development Test Modal (ODTM) has been conducted to verify, or update, the mathematical model used for load analysis. The approach used to assure the quality and validity of the experimental data is defined, the modal test is described, and test results are presented and compared with analysis results. Good correlation between the analyses and the test data assures an acceptable model for incorporation into the mathematical model of the launch system

    Burst size distributions in the digitized data of the ion chambers t Mt. Norikura and sea level stations

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    A practical and simple method for burst rejection is applied to the digitized data of cosmic ray ion chambers at Mt. Norikura, Tokyo and Kochi. As a result of burst rejection, the burst size frequency distributions in the digitized data at mountain altitude and sea level ion chambers is obtained. Results show that there are no significant differences between the digital and analog data processing in burst rejection

    <i>AKARI</i>/IRC source catalogues and source counts for the IRAC Dark Field, ELAIS North and the <i>AKARI</i> Deep Field South

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    We present the first detailed analysis of three extragalactic fields (IRAC Dark Field, ELAIS-N1, ADF-S) observed by the infrared satellite, AKARI, using an optimized data analysis toolkit specifically for the processing of extragalactic point sources. The InfaRed Camera (IRC) on AKARI complements the SpitzerSpace Telescope via its comprehensive coverage between 8–24 μm filling the gap between the Spitzer/IRAC and MIPS instruments. Source counts in the AKARI bands at 3.2, 4.1, 7, 11, 15 and 18 μm are presented. At near-infrared wavelengths, our source counts are consistent with counts made in other AKARI fields and in general with SpitzerIRAC (except at 3.2 μm where our counts lie above). In the mid-infrared (11 – 18 μm), we find our counts are consistent with both previous surveys by AKARI and the Spitzer peak-up imaging survey with the InfraRed Spectrograph (IRS). Using our counts to constrain contemporary evolutionary models, we find that although the models and counts are in agreement at mid-infrared wavelengths there are inconsistencies at wavelengths shortward of 7 μm, suggesting either a problem with stellar subtraction or indicating the need for refinement of the stellar population models. We have also investigated the AKARI/IRC filters, and find an active galactic nucleus selection criteria out to z AKARI 4.1, 11, 15 and 18 μm colours

    outlook for fish to 2020

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    Fish trade ,Fisheries Economic aspects Developing countries ,Fisheries Environmental aspects ,

    Fish as food

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    "This paper reports results of incorporating fish into IMPACT, a global model of food supply and demand that estimates market-clearing prices to 2020 for 32 commodities in 36 regions. It summarizes results for production, consumption, net exports and real price changes for 10 economic categories of fisheries items, disaggregated into 15 geographic regions of the world. Under the medium-variant scenario for the uncertain capture fisheries sectors, global production of food fish is projected to rise by 1.5% annually through 2020, with two-thirds of this from aquaculture, whose share in total food fish production rises to 41%. Global per capita fish consumption is projected to be 17.1 kg in 2020, with sensitivity analysis indicating a margin of 2 kg/capita either way based on extreme scenarios for capture and aquaculture. Most growth will occur in developing countries, which will account for 79% of food fish production in 2020. China's share of world production will continue to expand, while that of Japan, the EU, and former USSR will continue to contract. Real fish prices will rise 4 to 16% by 2020, while meat prices will fall 3%. Fishmeal and oil prices will rise 18%; use of these commodities will increasingly be concentrated in carnivorous aquaculture. Growing domestic demand will dampen fish exports from developing countries. Sensitivity analysis incorporating a very pessimistic view of capture fisheries leads to escalating food fish prices (+69% for high-value finfish) and soaring fishmeal prices (+134%), whereas an optimistic view of increased investment in aquaculture lowers real prices of low value food fish (-12%), and raises fishmeal prices (+42%)." Authors' AbstractFishery production Forecasting ,Food supply ,
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