In order tD enhance factory automation and unmanned productien, numerjcal controlled (NC) machine tools are widely used in many rnechanical processing factories, Whenever one machining part is changed to another, the operation of an NC machine tool has to be stopped in order to change some of the cutting teols on the turret too! holder. In this paper, a new concept of ttool module' is usect and the problem of reducing the number of tool changing operations for NC machine tools is diseussed, The problem is formulated as a O-1 integer pr(rgramming (O-1 ILP) problem on a bipartite graph and a branch and bound algorithm is proposed to select an optimal tool module. Since the LP relaxation problem obtained by dropping the integrality condition for the O-1 ILP problern has a special network structure like the well-known transportation problem, this LP is solved by certain network flow algorithm with utilizing its special structure Sorne numerical experiments are reported, and indicate that the algorithrn is reasonably efficient. FurtherTnore, possible extenslons of this method are discussed, which in turn ±ncreases the produc-t±vity. These bring an innovation in the aspect of factory management. However, the machine setup operations which tnclude the ehanging 205
To characterize the membrane transport responsible for the renal excretion and intestinal absorption of levofloxacin, we performed pharmacokinetic analysis of transcellular transport across LLC-PK 1 and Caco-2 cell monolayers. Transcellular transport of levofloxacin in LLC-PK 1 cells was greater in the basolateral-to-apical direction than in the opposite direction. Pharmacokinetic analysis indicated that basolateral uptake was the direction-determining step for the transcellular transport of levofloxacin in LLC-PK 1 cells. The apical efflux clearance of levofloxacin in LLC-PK 1 cells was increased at the medium pH 6 as compared with at pH 8, suggesting that membrane transport characteristics of levofloxacin are apparently similar to those of a prototypical organic cation, tetraethylammonium. On the other hand, transcellular transport of levofloxacin in Caco-2 cells was only slightly greater in the basolateral-to-apical direction than in the opposite direction. The apical efflux clearance of levofloxacin in Caco-2 cells was greater than basolateral efflux clearance, and apical influx clearance was greater than any other membrane transport clearance. In addition, the apical uptake of levofloxacin as well as quinidine in Caco-2 cells was inhibited significantly by nicotine and imipramine. The findings indicated that some transporters are responsible not only for the efflux but also for the influx of levofloxacin at the apical membrane of Caco-2 cells.
Microfabricated monolithic shock target arrays with embedded thin layers of dye-doped polymer films, termed optical nanogauges, are used to measure the velocity and pressure (Us=3.5 km/s; P=2.1 GPa) of picosecond-laser-driven shock waves in polymers. The 60 (±20) ps rise time of absorbance changes of the dye in the nanogauge appears to be limited by the transit time of the shock across the 300 nm thick gauge. The intrinsic rise time of the 2 GPa shock front in poly-methyl methacrylate must therefore be ≤60 ps. These measurements are the first to obtain picosecond resolution of molecular dynamics induced by the passage of a shock front through a solid. Good agreement was obtained between the nanosecond time scale shock-induced adsorption redshift of the dye behind the P=2 GPa shock front, and the redshift of a nanogauge, under conditions of static high pressure loading in a diamond anvil cell at P=2 GPa. Transient effects on the ≊100 ps time scale are observed in the dye spectrum, primarily on the red absorption edge where hot-band transitions are most significant. These effects are interpreted as arising from transient overheating and subsequent fast cooling of the dye molecules behind the shock front.
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