Vibration fixtures, at times, have resonant frequencies that exist in the frequency range needed for conducting vibration tests. These resonant frequencies can cause significant problems when running vibration tests over ranges which include these resonances. A test engineer will attempt to control the shaker system through a feedback accelerometer which controls the level of vibration input in...

BACKGROUND About 20 to 50 percent of accidents are due to some forms of carelessness and mindedness. Studies suggested that vibration is one of the most important physical factors in human performance when traveling on any sort of vehicles. The aim of this study was to investigate the effect of vehicles vibration on cognitive performance (attention and concentration). METHODS The sample consi...

According to the linear viscoelastic model, the population discrete elements under the vibration working condition of the seed tray of the seeder were assumed as rigid conditions to analyze the collision process. The dynamic characteristics among the population collision process for the vibration process of the seeder were analyzed by tracing the microcosmic motion of each seed. The following c...

original article   noise and vibration are the common problems in industrialized countries which can affect individual's job performance. the present study aimed to investigate the combination of the whole body vibration and the noise and their effects on the students' mental performance in the laboratory setting. twenty male students of tehran university of medical sciences, tehran, iran were ...

OBJECTIVES Prolonged exposure to severe chipping hammer vibration may cause hand-arm vibration syndrome. A reliable test method is required to select appropriate tools and assist in the development of better chipping hammers. In the present study, the ISO standardized test method (ISO 8662-2, 1992) was examined through an investigation of the vibration characteristics of chipping hammers operat...

The vehicular fuel cell stack is unavoidably impacted by the vibration and shock in the real-world due to the road unevenness. However, influences of vibration on fuel cell stack have yet to be investigated completely. In this paper, the performance of a fuel cell stack is experimentally studied in terms of gas-tightness, voltage degradation, AC impedance spectra, polarization curve and charact...