We present a systematic analysis of the eigenvalue problem associated with free vibrations of a finite piezoelectric body. The analysis is based on an abstract formulation of the three-dimensional theory of piezoelectricity. A series of fundamental properties of free vibrations of a piezoelectric body are proved concisely. The problem of free vibrations of a piezoelectric plate governed by the ...

Phonocardiography is-often more valuable than electrocardiography in timing mechanical events in the cardiac cycle. This study shows that the opening and closing of the mitral valve are related to the length of the previous heart cycle as demonstrated by the variations occuring in aluricular fibrillation. These variations in valve action are controlled by the pressure gradient between left auri...

Several people working on the 2nd floor of an office building complained about disturbing floor vibrations. The building consists of five floors. In the contrary to the other floors, the 2nd floor slab has no floor-to-ceiling secondary walls neither beneath nor on top of the slab. The modal parameters of four floors were identified using ambient vibration testing (AVT)-technology and a 5-kg-med...

Alpine skiing, both recreational and competitive, is associated with high rates of injury. Numerous studies have shown that occupational exposure to whole-body vibrations is strongly related to lower back pain and some suggest that, in particular, vibrations of lower frequencies could lead to overuse injuries of the back in connection with alpine ski racing. However, it is not yet known which f...

Understanding the role of shuttle vibrations in pore fluid distribution is an essential task in the exploration of plant growth in root modules aboard space flights. Results from experimental investigations are reported in this paper on the distribution of immiscible fluid phases in glass beads under vibrations. Hexadecane, a petroleum compound immiscible with and lighter than water, was used i...

The paper presents a new approach to the parameter identification of a wind turbine shaft vibrations measured with piezoelectric sensor. The system order and unknown processes matrices are determined using the wind force as the model input and wind turbine shaft vibrations as the model output. The identified model can be used to estimate the shaft vibrations and design an early damage monitorin...

hand-arm vibration can cause vascular, neurological and musculoskeletal disorders, collectively named as hand-arm vibration syndrome. the chainsaw is a portable machine that exposes own operators to high levels of hand-arm vibrations. this research focuses on vibration transmissibility from chainsaw handle to wrist and arm of operator. the vibration acceleration signals necessary for evaluation...