1,687 research outputs found

    Dynamic Characteristics of a Small Skyline Logging System with a Guyed Tailspar

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    A series of dynamic loading tests were conducted on a small skyline logging system (15.8 mm [5/8 inch] skyline) operating in a second-growth Douglas fir stand. The tests included free vibration tests and logging tests with turns weighing from 1.5 to 9 kN [340 to 2050 lbs]. Natural frequency and damping were evaluated from free vibration tests, and the free vibration portion of logging tests. Dynamic load magnitude was evaluated for logging tests with natural and artificial breakouts of turns with a range in turn weights, and for a series of logging tests with the same turn. The natural frequencies of the guylines were in good agreement with simple cable theory. However, the presence of the carriage on the skyline resulted in measured natural frequencies significantly lower than simple cable theory would predict. Damping of the tailspar system and the skyline averaged about 10% of critical damping, but was highly variable from test to test. Dynamic load magnitude, whether expressed as the load peak produced by turn break-out, or the maximum cyclic load, was highly variable, with coefficients of variation ranging from 31 to 79%. Even a series of logging tests with the same two-log turn produced maximum cyclic loads with a coefficient of variation of nearly 40%

    Computer Model for Dynamic Skyline Behaviour

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    The development and experimental verification of a numerical model for the dynamic behavior of a cable logging system skyline is discussed. The model is intended to simulate the skyline behavior after a turn of logs breaks out of a "hang-up" on the ground. Output from the model may be used as a forcing function for a dynamic load on the tailspar or other component of the cable logging system. The numerical model uses finite difference and Runge-Kutta techniques. Output from the model consists of time-histories of the fluctuations in skyline tensions. From this output the frequencies of the skyline vibrations may be determined. The model was verified by experimental data collected while operating a small cable logging system in Oregon State University's McDonald Research Forest

    Position-sensitive detection of ultracold neutrons with an imaging camera and its implications to spectroscopy

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    Position-sensitive detection of ultracold neutrons (UCNs) is demonstrated using an imaging charge-coupled device (CCD) camera. A spatial resolution less than 15 μ\mum has been achieved, which is equivalent to an UCN energy resolution below 2 pico-electron-volts through the relation δE=m0gδx\delta E = m_0g \delta x. Here, the symbols δE\delta E, δx\delta x, m0m_0 and gg are the energy resolution, the spatial resolution, the neutron rest mass and the gravitational acceleration, respectively. A multilayer surface convertor described previously is used to capture UCNs and then emits visible light for CCD imaging. Particle identification and noise rejection are discussed through the use of light intensity profile analysis. This method allows different types of UCN spectroscopy and other applications.Comment: 12 figures, 28 pages, accepted for publication in NIM

    State-of-the-art in lean design engineering:a literature review on white collar lean

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    Lean is usually associated with the ‘operations’ of a manufacturing enterprise; however, there is a growing awareness that these principles may be transferred readily to other functions and sectors. The application to knowledge-based activities such as engineering design is of particular relevance to UK plc. Hence, the purpose of this study has been to establish the state-of-the-art, in terms of the adoption of Lean in new product development, by carrying out a systematic review of the literature. The authors' findings confirm the view that Lean can be applied beneficially away from the factory; that an understanding and definition of value is key to success; that a set-based (or Toyota methodology) approach to design is favoured together with the strong leadership of a chief engineer; and that the successful implementation requires organization-wide changes to systems, practices, and behaviour. On this basis it is felt that this review paper provides a useful platform for further research in this topic

    The Distribution, Excitation and Formation of Cometary Molecules: Methanol, Methyl Cyanide and Ethylene Glycol

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    We present an interferometric and single dish study of small organic species toward Comets C/1995 O1 (Hale-Bopp) and C/2002 T7 (LINEAR) using the BIMA interferometer at 3 mm and the ARO 12m telescope at 2 mm. For Comet Hale-Bopp, both the single-dish and interferometer observations of CH3OH indicate an excitation temperature of 105+/-5 K and an average production rate ratio Q(CH3OH)/Q(H2O)~1.3% at ~1 AU. Additionally, the aperture synthesis observations of CH3OH suggest a distribution well described by a spherical outflow and no evidence of significant extended emission. Single-dish observations of CH3CN in Comet Hale-Bopp indicate an excitation temperature of 200+/-10 K and a production rate ratio of Q(CH3CN)/Q(H2O)~0.017% at ~1 AU. The non-detection of a previously claimed transition of cometary (CH2OH)2 toward Comet Hale-Bopp with the 12m telescope indicates a compact distribution of emission, D<9'' (<8500 km). For the single-dish observations of Comet T7 LINEAR, we find an excitation temperature of CH3OH of 35+/-5 K and a CH3OH production rate ratio of Q(CH3OH)/Q(H2O)~1.5% at ~0.3 AU. Our data support current chemical models that CH3OH, CH3CN and (CH2OH)2 are parent nuclear species distributed into the coma via direct sublimation off cometary ices from the nucleus with no evidence of significant production in the outer coma.Comment: accepted for publication in Ap

    FAPRI 2006 U.S. and World Agricultural Outlook

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    The FAPRI 2006 U.S. and World Agricultural Outlook presents projections of world agricultural production, consumption, and trade under average weather patterns, existing farm policy, and policy commitments under current trade agreements and custom unions. Despite continued high energy prices, world economic growth is expected to remain strong in the coming decade, above 3% per annum. Other major drivers of the 2006 baseline include new bio-energy policies in several large countries, EU sugar policy reform, sanitary and phytosanitary (SPS) shocks in livestock and poultry markets, and movements in the exchange rate.Crop Production/Industries, International Relations/Trade, Livestock Production/Industries,
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