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Braking performance analysis of an escalator system using multibody dynamics simulation technology
박찬종,Gero Gschwendtner 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.7
An escalator brake system composed of an operational brake and an auxiliary brake is one of the most critical components that directlyinfluence passenger safety. Therefore, understanding the braking performance of an escalator system at the early design stage is imperative. In this article, the application of multibody dynamics simulation for escalator industry is discussed. This study proposes an efficientmultibody dynamics simulation modeling approach that considers the dynamic effects of a step band, handrail band, and passenger trafficload, which requires considerable computational resources when the conventional method is employed. The approach also covers a comprehensivesimulation modeling of drive machine with gearbox, main drive chain band, operational brake system, and auxiliary brakesystem to evaluate the escalator’s braking performance at the system level. The simulation model is verified with actual measurementdata and employed to investigate potential worst case braking scenarios. The dynamic influences of these braking scenarios on the escalatorsystem are discussed as a result.
Impurity-Mediated Early Condensation of a Charge Density Wave in an Atomic Wire Array
Yeom, Han Woong,Oh, Deok Mahn,Wippermann, Stefan,Schmidt, Wolf Gero American Chemical Society 2016 ACS NANO Vol.10 No.1
<P>We directly show how impurity atoms induce the condensation of a representative electronic phase, the charge density wave (CDW) phase, in atomic scale with scanning tunneling microscopy. Oxygen impurity atoms on the self-assembled metallic atomic wire array on a silicon crystal condense the CDW locally above the pristine transition temperature. More interestingly, the CDW along the wires is induced not by a single atomic impurity but by the cooperation of multiple impurities. First principles calculations disclose the mechanism of the cooperation as the coherent superposition of the local lattice strain induced by impurities, stressing the coupled electronic and lattice degrees of freedom for the CDW. This opens the possibility of the strain engineering over electronic phases of atomic-scale systems.</P>