the occurrence of chatter vibrations in boring operation has a great influence in improving workpiece dimensional accuracy, surface quality and production efficiency. in this paper instability analysis of machining process is presented by dynamic model of boring machine. this model, which consists of machine tool’s structure, is provided by finite element method and ansys software. the model is...

greater levels of complexity in tunnelling with tunnel boring machine (tbm) allow higher chances of failures that may increase the potential hazardous risks. this paper presents the results of a study on tbm reliability using risk analysis. machinery failure mode and effect analysis was applied to analyze the risks of a tbm using qs9000 and sae.j1739 recommendations. for this purpose, 48 failur...

Kurzban et al. argue that the experiences of "effort," "boredom," and "fatigue" are indications that the costs of a task outweigh its benefits. Reducing the costs of tasks to "opportunity costs" has the effect of rendering tasks costless and of denying that they can be inherently boring or tedious, something that "vigilance tasks" were intentionally designed to be.