BACKGROUND Whole-body-vibrations are often associated with adverse health effect but the long term effects are less known. This study investigates the association between occupational exposures to whole-body vibrations, and subsequent transition to disability pension. METHODS A total of 4215 male employees were followed up for subsequent disability pension retirement. Exposure to whole-body-v...

Previous studies of the flow created inside a cylindrical cavity ~radius R , height H) of fluid by a single rotating end wall have shown that over a range of cylinder aspect ratios 1.6&H/R&2.8, the first unsteady flows to bifurcate with increasing Reynolds number retain axisymmetry, and subsequent bifurcations break axisymmetry to give solutions with modulated rotating wave ~MRW! states. The un...

Axisymmetric pulsations of rotating neutron stars can be excited in several scenarios, such as core-collapse, crust and core-quakes and binary mergers and could become detectable either in gravitational waves or high-energy radiation. Here, we present a comprehensive study of all low-order axisymmetric modes of uniformly and rapidly rotating relativistic stars. Initial stationary configurations...

Arterial bleeding into a free space is known to cause local vibrations in tissue. To study the effectiveness of utilizing these tissue vibrations in localizing the site of arterial bleeding, we have developed an algorithm for ultrasonically imaging these tissue vibrations. Simulation results indicate that our algorithm can correctly detect vibrations in the presence of pulsatile wall motion, bl...

Flow induced vibrations are an important concern in the design of nuclear reactors. One of the possible designs of the 4th generation nuclear reactors is a lead-cooled fast reactor of which MYYRHA is a prototype. The combination of high liquid density, flow velocity, low pitch-todiameter ratio and the absence of grid spacers makes this design prone to flow induced vibrations. Although most vibr...

The purpose of introducing ultrasonic vibrations in the tube hydroforming process is to create more formability by obtaining a lower corner radius, improve thickness distribution of the wall and provide good tribological conditions at the tube and the die interface. Vibrations imposed on the die create alternating gaps which improve the formability in the tube hydroforming process in the presen...

We study event horizons of non-axisymmetric black holes and show how features found in axisymmetric studies of colliding black holes and of toroidal black holes are non-generic and how new features emerge. Most of the details of black hole formation and black hole merger are known only in the axisymmetric case, in which numerical evolution has successfully produced dynamical space-times. The wo...

We study stationary and axisymmetric solutions of General Relativity, i.e. pure gravity, in four or higher dimensions. D-dimensional stationary and axisymmetric solutions are defined as having D−2 commuting Killing vector fields. We derive a canonical form of the metric for such solutions that effectively reduces the Einstein equations to a differential equation on an axisymmetric D − 2 by D − ...

The article presents resarches for designing and manufacturing of the ultrasonic motors that uses piezoceramic materials. There are presented specific vibrations modes for the studied piezoceramic plates, vibrations that are used to excite the motor activated element (mobile element). Using the finite element method it is really posssible to predict the usefull vibrations that can makes easier ...