This paper describes the measurement of oil film thickness between rolling element and inner raceway in cylindrical roller bearing. A fine piezoelectric element is bonded on the inner surface of the inner ring to measure the reflection coefficient of oil between rolling element and inner raceway. The quasi-static spring model is used to calculate oil film thickness from the corrected reflection coefficient data. Experiments are described on a simplified cylindrical roller bearing configured by one cylindrical roller, 11 ø , and an inner ring from a NU209EM bearing. Reasonable agreement is shown over several loads and speeds with predictions from elastohydrodynamic lubrication (EHL) theory.

In Denmark the public water supply is practically 100% served by groundwater abstracted from nearly 20.000 water wells. During time of operation the productivity from a well will often decrease drastically. This impaired performance is usually caused by well clogging. This clogging makes the well economically inefficient for the operator and therefore needs to be rehabilitated. This article examines the performance and evaluates the effectiveness of high power ultrasonics for water well rehabilitation. Special focus is drawn to the inconsistent efficiency of the currently, rarely used ultrasonic cleaning method caused by the specific varying conditions in water wells and correlated ultrasound intensity losses. The scope for improving the, in Denmark, rarely used ultrasonic cleaning method efficiency is investigated and suggestions for improvements based on a proof-of-concept prototype are given based on empirical- as well as theoretical studies.

The design of high-sensitive hydrophones is one of the research interests in underwater acoustics. Due to progress of micro- and nanotechnology the most attention of researchers is attracted by the transducers that use the micro-electromechanical system (MEMS) concept. Piezoelectric micro-machined ultrasonic transducers (pMUTs) present a new approach to sound detection and generation that can overcome the shortcomings of conventional transducers. For accurate ultrasound field measurement, small size hydrophones which are smaller than the acoustic wavelength are required for providing an omnidirectional response and avoid spatial averaging. This paper presents some results of multiobjective optimization for membrane-type piezoceramic MEMS based transducers. We investigate the miniaturized membrane-type sensor with perforated holes in the active PZT and intermediate membranes, with the protective plates and a vacuum chamber. An influence of the protective plate elastic and viscous properties, the dimensions and the relative area of the perforated holes on the sensitivity’s frequency response of the hydrophone was studied for the broadening and equalizes the operating frequency band. We optimize these key parameters using the Pareto approach with the finite element (FE) model of coupled piezoelectric-acoustic problem. Finally, the set of optimized hydrophone structures and some examples of obtained sensitivity frequency response are demonstrated.

This paper presents a possibility to use Resonant Ultrasound Spectroscopy as nondestructive evaluation method for ceramic elements of prosthesis such as ceramic femoral heads. With this method can be emphasized the incorrect sintering of these elements as well as eventually cracks. If the number of resonance peaks is big enough, the elements of elasticity matrix can be determined, demonstrated by effective measurements on zirconia with different stabilizers cylindrical samples taken into study.

This paper introduces the research carried out on the design of a robotized teleechography system. Such a system is composed of a master control device and a slave robotic manipulator. Our objective is to contribute to the French Agence National de Recherche (ANR) project PROSIT by designing both devices. To define the kinematic architecture, we had proposed an approach based on the analysis of the expert gesture as a first step of the design process. We have used a motion capture system to study the ultrasound examination gesture and to define the kinematic specifications for the proposed manipulator. A new kind of architecture was selected: the spherical parallel mechanism (SPM). We have chosen it because it reaches the constraint requirements. The kinematic architecture was synthesized by executing a real-coded genetic algorithm (GA). We integrated optimization criteria in the synthesis of the selected architecture. We have fixed a minimum required workspace and we have chosen to optimized the SPM in terms of dexterity and compacity. Another important part of our research was to design a haptic device to provide a very intuitive control of the tele-operated robot. We have opted for a free hand interface that integrates an active force control and feedback. An Inertial Measurement Unit (IMU) has been integrated. The data collected from the IMU that we integrated are processed by a Kalman Filter. But we have modified this predictor-estimator tool from the state of art to adapt its behavior with respect to the type of motion done by the operator. Experimentations via our motion capture system have demonstrated the accuracy of this orientation control strategy. The final step will be the experimental and clinical validation on real patients.

This paper presents the resonant ultrasound spectroscopy method that allows, in principle, the determination of the density changing, elastic and geometrical properties of the object to be examined. The method is applied at the noninvasive evaluation of the femoral head prosthetic and of the artificial cervical discs made from yttria stabilized tetragonal zirconia. In the case of density changing, the spectral lines are displacing to smaller frequencies and in the case of the cracks, supplementary peaks appear.

Mobile Spatial coordinate Measuring System (MScMS) is a wireless-sensor-network based system developed at the Industrial Metrology and Quality Engineering Laboratory of DISPEA – Politecnico di Torino. It has been designed to perform simple and rapid indoor dimensional measurements of medium-large size objects (large scale metrology). It is made up of three basic parts: a “constellation” of wireless devices (Crickets), a mobile probe, and a PC to store and elaborate data. Crickets and mobile probe use ultrasound (US) transceivers in order to evaluate mutual distances. Each US device has a communication range limited by a cone of transmission within a nominal opening angle of about 170° and a maximum distance of no more than 8 m. The mobile probe location in the working volume is obtained by a trilateration, consequently it should communicate with at least 4 constellation devices at once. The system makes it possible to calculate the position — in terms of spatial coordinates — of the object points “touched” by the probe. Acquired data are then available for different types of elaboration (determination of distances, curves or surfaces of measured objects). During the system set-up, the constellation Crickets (beacons) are manually placed in the working volume (we define this operation as “positioning”). After that, their coordinates are determined as much precisely as possible (this operation is said “location”). The positioning of constellation devices is one of the most critical aspects in the system set-up. In principle, Crickets can be arranged without restrictions all around the measured object. However, the number and position of network devices are strongly related to the dimensions and shape of both the measuring volume and the measured object. The accuracy in the location of constellation devices is fundamental for the accuracy of the coordinates of the touched points during measurement operation. It is important to assure a full coverage of the space served by network devices by a proper alignment of US transmitters. For that reason, an ad hoc software “pre-processor” has been developed in order to help the operator in positioning and locating constellation devices in the working volume, according to the measuring space and the measured object dimensional characteristics. The aim of the paper is to introduce and describe this computer-assisted approach. Some preliminary results of experimental tests carried out on the system prototype are also presented and discussed.

While low intensity therapeutic ultrasound irradiation (LITUS) has been shown to have biological effects on tissue and cells, the physical mechanism leading to those effects has yet to be characterized. As a model system to study effects of LITUS on intracellular organelles, we monitor the dynamics of nanoparticles suspended in a viscoelastic medium, before and during LITUS treatment. Particle motion dynamics can indicate: i) forces acting on similarly-sized intracellular organelles; ii) streaming flow induced in cells and in cavities in contact with cells; and iii) instantaneous (under LITUS) changes in the mechanical properties of viscoelastic media in general and cells in particular. Forces and flow can result in shear stresses that act on the cell membrane of, e.g., endothelial cells in blood vessels and may cause biophysical responses. Particle motion in a high-viscosity, viscoelastic model solution, methyl cellulose, was used as an indicator for sample response under LITUS. The ultrasound-induced motion of nano-particles was quantified by real-time particle-tracking microrheology methods. Particle motion without LITUS irradiation demonstrated diffusive-like behavior with no underlying convection. In contrast, during LITUS irradiation convective motion with a particle-velocity profile parabolic in time was observed. Particles were accelerated after initiation of LITUS irradiation, then a transient phase of constant velocity was observed, and finally the speed was reduced. Altogether the results of the study indicate that LITUS may apply considerable direct forces on suspended particles, a model system for cellular organelles. More studying will help elucidate the mechanisms of LITUS effects. Extending this approach to cells in vitro and evaluating their response can promote the use of ultrasound as a therapeutic tool for delicate manipulation of cells in vivo in a controlled, targeted, and non-invasive way. At the same time, one can define the safety limits and optimal range for therapeutic and diagnostic ultrasound by indicating the threshold for irreversible intracellular changes.