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...

nowadays, atomic force microscope is considered as a useful tool in the determination of intermolecular forces and surface topography with the resolution of nanometers. in this kind of microscope, micro cantilever is considered as the heart of the microscope and is used as a measuring tool.  this paper is aimed towards investigating the behavior of a piezoelectric micro cantilever with a triang...

The low-frequency Raman spectra of Na-and Cs-DNA water solutions have been studied to determine the mode of counterion vibrations with respect to phosphate groups of the DNA double helix. The obtained spectra are characterized by the water band near 180 cm −1 and by several DNA bands near 100 cm −1. The main difference between Na-and Cs-DNA spectra is observed in case of the band 100 cm −1. In ...