1,798 research outputs found

    Manual for the District Fisheries Analysis System (FAS): A Package for Fisheries Management and Research. Part 1: Fish Population Survey Data (DOC9 Data Base)

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    Report issued on: issued September, 1987INHS Technical Report prepared for unspecified recipien

    Quantum quenches in a spinor condensate

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    We discuss the ordering of a spin-1 condensate when quenched from its paramagnetic phase to its ferromagnetic phase by reducing magnetic field. We first elucidate the nature of the equilibrium quantum phase transition. Quenching rapidly through this transition reveals XY ordering either at a specific wavevector, or the `light-cone' correlations familiar from relativistic theories, depending on the endpoint of the quench. For a quench proceeding at a finite rate the ordering scale is governed by the Kibble-Zurek mechanism. The creation of vortices through growth of the magnetization fluctuations is also discussed. The long time dynamics again depends on the endpoint, conserving the order parameter in zero field, but not at finite field, with differing exponents for the coarsening of magnetic order. The results are discussed in the light of a recent experiment by Sadler \emph{et al.}Comment: Published versio

    Manual for the Fish Population Surveys (DOC9 Package) for the District Fisheries Analysis System (FAS)

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    Update of Aquatic Biology Technical Report 87/11; final report of project F-69-R (1-3), Data Base Management and Analysis of Fisheries in ImpoundmentsReport issued on: issued October 1990INHS Technical Report prepared for Illinois Department of Conservatio

    The Fisheries Analysis System (FAS): Creel Survey and Lake Analyses

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    F-69-R(1-3)Report issued on: October 1990Final report of Project F-69-R(1-3), Data Base Management and Analysis of Fisheries in Impoundments, conducted under of memorandum of understanding between Illinois Department of Conservation and the University of Illinois, supported through Fed(TRUNCATED

    Experimental Wear Modelling of Lifeboat Slipway Launches

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    It is necessary to use an inclined slipway to launch lifeboats in locations where there is no natural harbour. Slipway stations consist of an initial roller section followed by an inclined keelway, the lifeboat is released from the top of the slipway and proceeds under its own weight into the water. Contact is between the lifeboat keel and a lined, greased keelway and this that determines the friction along the slipway. This paper describes a bench test methodology to investigate this contact. The selection of a modified TE57 reciprocating tribometer and design of a modified pin on plate arrangement is discussed. A test schedule for both the original nickel/chromium coated steel lining and the new low-friction jute fibre/phenolic resin composite lining is developed to accurately reflect real world conditions including environmental contamination such as seawater or wind-blown sand. Environmentally conscious lubricants including water and bio-greases are investigated and compared for their effects in reducing slipway panel friction and wear. Experimental data is collected to establish wear mechanisms, wear volumes and friction characteristics for a range of lubricants and environmental contaminants for the two most common lifeboat keelway lining materials. Implications of this research for future lifeboat slipway design are discussed

    Wear and Friction Modeling on Lifeboat Launch Systems

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    The RNLI provides search and rescue cover along the UK and RoI coast using a variety of lifeboats and launch techniques. In locations where there is no natural harbour it is necessary to use a slipway to launch the lifeboat into the sea. Lifeboat slipway stations consist of an initial section where the boat is held on rollers followed by an inclined keelway lined with low friction composite materials, the lifeboat is released from the top of the slipway and proceeds under its own weight into the water. The lifeboat is later recovered using a winch line. It is common to manually apply grease to the composite slipway lining before each launch and recovery in order to ensure sufficiently low friction for successful operation. With the introduction of the Tamar class lifeboat it is necessary to upgrade existing boathouses and standardise slipway operational procedures to ensure consistent operation. The higher contact pressures associated with the new lifeboat have led to issues of high friction and wear on the composite slipway linings and the manual application of grease to reduce friction is to be restricted due to environmental impact and cost factors. This paper presents a multidisciplinary approach to modelling slipway panel wear and friction using tribometer testing in conjunction with finite element analysis and slipway condition surveys to incorporate common real-world effects such as panel misalignments. Finally, it is shown that a freshwater lubrication system is effective, reducing cost and environmental impacts while maintaining good friction and wear performance

    Some Finite Size Effects in Simulations of Glass Dynamics

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    We present the results of a molecular dynamics computer simulation in which we investigate the dynamics of silica. By considering different system sizes, we show that in simulations of the dynamics of this strong glass former surprisingly large finite size effects are present. In particular we demonstrate that the relaxation times of the incoherent intermediate scattering function and the time dependence of the mean squared displacement are affected by such finite size effects. By compressing the system to high densities, we transform it to a fragile glass former and find that for that system these types of finite size effects are much weaker.Comment: 12 pages of RevTex, 4 postscript figures available from W. Ko

    New apparatus for DTA at 2000 bar: thermodynamic studies on Au, Ag, Al and HTSC oxides

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    A new DTA (Differential Thermal Analysis) device was designed and installed in a Hot Isostatic Pressure (HIP) furnace in order to perform high-pressure thermodynamic investigations up to 2 kbar and 1200C. Thermal analysis can be carried out in inert or oxidising atmosphere up to p(O2) = 400 bar. The calibration of the DTA apparatus under pressure was successfully performed using the melting temperature (Tm) of pure metals (Au, Ag and Al) as standard calibration references. The thermal properties of these metals have been studied under pressure. The values of DV (volume variation between liquid and solid at Tm), ROsm (density of the solid at Tm) and ALPHAm (linear thermal expansion coefficient at Tm) have been extracted. A very good agreement was found with the existing literature and new data were added. This HP-DTA apparatus is very useful for studying the thermodynamics of those systems where one or more volatile elements are present, such as high TC superconducting oxides. DTA measurements have been performed on Bi,Pb(2223) tapes up to 2 kbar under reduced oxygen partial pressure (p(O2) = 0.07 bar). The reaction leading to the formation of the 2223 phase was found to occur at higher temperatures when applying pressure: the reaction DTA peak shifted by 49C at 2 kbar compared to the reaction at 1 bar. This temperature shift is due to the higher stability of the Pb-rich precursor phases under pressure, as the high isostatic pressure prevents Pb from evaporating.Comment: 6 figures, 3 tables, Thermodynamics, Thermal property, Bi-2223, fundamental valu
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