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  • 1
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 505-507 (Jan. 2006), p. 649-654 
    ISSN: 1662-9752
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Biochip is an emerging technology and has evoked great research interests in recent years. In this paper, a novel air-driven loop-type microfluidic biochip was investigated. Differing from conventional micro channels, this chip has a micro loop-channel and 3 sets of driving conduits with valveless design in their intersections so that the microfluid can be driven smoothly in unidirectional circular movements. The driving efficiency reaches the highest if the entry angle of driving conduitsis in the tangent direction of the loop-channel. However, the smaller the included angle, the impact area the larger, leading to comparatively serious reflow phenomenon. Furthermore, the microfluid can be controlled to stop almost instantaneously in the loop segment. Therefore, this loop-typebiochip is suitable for biochemical reactions under repeated multiple temperature operations such as polymerase chain reaction. A full circular movement completes a cycle of PCR amplification. Besides, this biochip has its merits including simpler chip design, shorter channel length, and flexible controllability for biochemical reactions
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 594 (Aug. 2008), p. 389-400 
    ISSN: 1662-9752
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: In this paper, the mathematic model of the swashplate type variable displacement axialpiston pump (VDAPP) is established. The VDAPP applied to an electro-hydraulic servo controlsystem usually induces unstable performance, so that a servo controller is designed and analyzed tocontrol the swashplate angular displacement and improve the stability and transient response of pumpperformance. The flow and pressure variations of pump with the proposed controller are investigatedand analyzed by mathematic simulations and experiments. The simulation and experiment resultsshow that the proposed controller can improve the stability of swashplate angular displacement, andeasily applied to the energy saving hydraulic systems
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0036-8792
    Source: Emerald Fulltext Archive Database 1994-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Purpose - The present paper proposes a theoretical analysis of the stability characteristics of a Jeffcott rotor-hybrid bearing system. It is intended that on the basis of the numerical results drawn from this study, appropriate recess depth, land size, orifice location and speed parameter for stable operation can be determined for use in the bearing design process. Design/methodology/approach - A Jeffcott rotor supported by hybrid oil film bearings with dual-row recesses and orifice- compensated restrictors is studied. In order to facilitate the calculation of film dynamics, using the perturbation method, the Reynolds equation was linearized and subsequently solved using finite difference techniques, whilst the stability maps were determined by the Routh-Hurwitz method. Findings - The data reported here suggest that the stability characteristics of the Jeffcott rotor-bearing system could be improved by the use of shallow, dual-recessed hybrid bearings with orifice compensation. In addition to greater eccentricity ratios, smaller land-width ratios and greater shaft stiffness may also provide shallow-recessed bearings with better stability. In all cases, the stability provided by upstream orifice-sited bearings is better than that provided by center orifice-sited bearings, whilst high-speed parameters may also provide a greater stability threshold. Originality/value - This study proposes an extensive database as a critical requirement in the design of hybrid bearings, in order to ensure that a rotor bearing system is operating stably.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    International Journal for Numerical Methods in Fluids 9 (1989), S. 1381-1394 
    ISSN: 0271-2091
    Keywords: Heat exchangers ; Crossflow ; Tube bundle ; Nusselt number ; Streamfunction/vorticity ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: A numerical scheme is developed to predict the heat transfer and pressure drop coefficients in flow through rigid tube bundles. The scheme uses the Galerkin finite element technique. The conservation equations for laminar steady-state flow are cast in the form of streamfunction and vorticity equations. A Picard iteration method is used for the solution of the resulting system of non-linear algebraic equations. Results for the heat transfer and pressure drop coefficients are obtained for tube arrays of pitch ratios of 1·5 and 2·0. Very good agreement of the present results and experimental data obtained in the past is observed up to Reynolds numbers of 1000. It is also observed that the results of the present method show better agreement with the experimental data and that they are applicable for higher Reynolds numbers than results of other studies.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
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