共查询到10条相似文献,搜索用时 39 毫秒
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This research involves the development and evaluation of a part flow control model for a type of flexible manufacturing system (FMS) called a dedicated flexible flow line (FFL). In the FFL, all part types flow along the same path between successive machine groups. The specific objective of the part flow control model for the FFL is to minimize makespan for a given set of parts produced in a FFL near-term schedule, given fixed available buffer constraints. The control model developed in this research involved the repeated, real-time execution of a mathematical programming algorithm. The algorithm attempts to release the right mix of parts at the tight time to keep the FFL operating smoothly. The focus of the approach is directed toward managing WIP buffers for each machine group queue. The algorithm specifically incorporates stochastic disturbance factors such as machine failures. Through a limited number of simulation experiments, performance of the control model is shown to be superior to other parts releasing and control methods reported in the literature. 相似文献
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Bone flow 总被引:1,自引:0,他引:1
L Krook L F Bélanger P A Henrikson L Lutwak B E Sheffy 《Revue canadienne de biologie / éditée par l'Université de Montréal》1970,29(2):157-167
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Cardot P Battu S Simon A Delage C 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》2002,768(2):285-295
Interest in the development of field flow fractionation (FFF) systems for cell sorting recently increased with the possibility of collecting and characterizing viable cellular materials. There are various tools for the analysis of cell characteristics, but the reference is small- and large-angle light scattering often coupled with fluorimetric measurements. The well-known flow cytometry (FC) cell analysis techniques can be associated with FFF leading to the possibility of collecting information provided by a remarkable separation technique for micron-sized particles (cells) operating in the steric-hyperlayer elution mode with multiparametric detection provided by flow cytometry. Moreover FFF derived cell characteristics can be correlated with FC characteristics to describe in a unique way the nature of the eluted materials. Experimental demonstrations are described herein using nucleated cells (HL-60 cell lineage) and human red blood cells (HRBC). 相似文献
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Claessens TE Van Herck PL Matthys KS Segers P Vrints CJ Verdonck PR 《Biomechanics and modeling in mechanobiology》2004,3(1):48-55
Fractional flow reserve (FFR) is a commonly used index to assess the functional severity of a coronary artery stenosis. It is conventionally calculated as the ratio of the pressure distal (Pd) and proximal (Pa) to the stenosis (FFR=Pd/Pa). We hypothesize that the presence of a zero flow pressure (P
zf), requires a modification of this equation. Using a dynamic hydraulic bench model of the coronary circulation, which allows one to incorporate an adjustable P
zf, we studied the relation between pressure-derived FFR=Pd/Pa, flow-derived true FFRQ=QS/QN (=ratio of flow through a stenosed vessel to flow through a normal vessel), and the corrected pressure-derived FFRC=(Pd–Pzf)/(Pa–Pzf) under physiological aortic pressures (70 mmHg, 90 mmHg, and 110 mmHg). Imposed Pzf values varied between 0 mmHg and 30 mmHg. FFRC was in good agreement with FFRQ, whereas FFR consistently overestimated FFRQ. This overestimation increased when Pzf increased, or when Pa decreased, and could be as high as 56% (Pzf=30 mmHg and Pa=70 mmHg). According to our experimental study, calculating the corrected FFRC instead of FFR, if Pzf is known, provides a physiologically more accurate evaluation of the functional severity of a coronary artery stenosis. 相似文献
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Gharib M Pereira F Dabiri D Hove JR Modarress D 《Integrative and comparative biology》2002,42(5):964-970
Quantitative flow visualization has many roots and has takenseveral approaches. The advent of digital image processing hasmade it possible to practically extract useful information fromevery kind of flow image. In a direct approach, the image intensityor color (wavelength or frequency) can be used as an indicationof concentration, density and temperature fields or gradientsof these scalar fields in the flow (Merzkirch, 1987). For whole-fieldvelocity measurement, the method of choice by experimental fluidmechanicians has been the technique of Particle Image Velocimetry(DPIV). This paper presents a novel approach to extend the DPIVtechnique from a planar method to a full three-dimensional volumemapping technique useful in both engineering and biologicalapplications. 相似文献