The methodology of modelling and of qualitative analysis of large rotating systems with gear and bearing couplings is presented. The emphasis is laid on the modelling of nonlinear gear and bearing couplings and on their influence on the dynamic system response to the internal kinematic excitation in gearing and to parametric excitation caused by the time-varying meshing stiffness. The aim is to introduce a method of investigation the beahviour of the rotating system influenced by the mentioned excitation and to examine the influence of chosen operational parameters. The methodology of modelling and of qualitative dynamic behaviour analysis is tested on a two-stage gearbox. and Obsahuje seznam literatury
Caterpillars of the poplar lutestring moth, Tethea or, construct leaf shelters that they defend against intruding conspecifics using a combination of vibratory signals and physical aggression. Staged interactions between a resident caterpillar and introduced conspecific were recorded with a video camera and laser vibrometer. Residents crawl towards the intruder and perform three behaviours: lateral hitting, pushing, and mandible scraping. Vibrations caused by mandible scraping result from the caterpillar repeatedly scraping opened mandibles laterally against the leaf surface in bouts lasting 1.16 ± 0.39 s, with an average of 4 ± 1 scrapes per bout. We propose that these scrapes function in leaf shelter defense against conspecifics for the following reasons: Mandible scrapes are produced only by residents; they are generated when a resident is approached by an intruder; the rate of scraping increases as the intruder approaches the shelter; and residents in all trials retain their shelters, with the intruder leaving the leaf within 127.9 ±104.3s from the beginning of the trial. The function and evolutionary origins of vibration-mediated territoriality in caterpillars are discussed. and Jaclyn L. Scott, Jayne E. Yack.