Conventional data transmission via cable or electromagnetic waves reaches their limits in harsh or hard-to-reach environments. For example in bore hole inspection, cables can break and electromagnetic waves cannot pass different earth layers. Actual studies showing that guided waves are a possible instrument for cable less data transmission. The known technique works with frequencies below 100 kHz for a wave propagating of long distances and known time delays. This concept limits the data transmission rate to e.g. 250 bit/s at a 2m long steel pipe. Other cable less developments are also known in so-called "wall to wall" communication by means of ultrasonic sound waves. Here, frequencies of 1 MHz are used to transmit data in the order of 550 bit/s through one wall with opposing transducers. In our approach we are using guided waves with a center frequency of 1 MHz. Furthermore a sweep mode is used instead of the pulse position modulation (PPM). Thus, it is possible to be independent of a known transmitter and receiver position and thereby the knowledge of the time delay. Thereby, in contrast to the already known technology it is possible to use a two-dimensional arbitrary surface for data communication. At a first experiment, a data transmission distance of 20 cm at a 3 mm glass plate was build. One single-phase transducer is used as transmitter and two different transducers as receiver to show the independence of position of the receiver. Wave reflections at the edges of the glass plate and dispersion of the guided wave could also be eliminated by the here used algorithm of identifying the biggest amplitude of the received signal. Thereby a transmission rate of 1,5 kBit/s with good SNR could be observed.

The monitoring of liquid-filled tubes with respect to the formation of soft deposition layers such as biofilms on the inner walls calls for non-invasive and long-term stable sensors, which can be attached to existing pipe structures. For this task a method is developed, which uses an ultrasonic clamp-on device. This method is based on the impact of such deposition layers on the propagation of circumferential guided waves on the pipe wall. Such waves are partly converted into longitudinal compressional waves in the liquid, which are back-converted to guided waves in a circular cross section of the pipe. Validating this approach, laboratory experiments with gelatin deposition layers on steel tubes exhibited a distinguishable sensitivity of both wave branches with respect to the thickness of such layers. This allows the monitoring of the layer growth.

A previous experiment showed that the rate of the electropolishing of a copper anode may be increased by twofold when generating a 60 KHz to 1.7 MHz frequency vibration in the anode. In this work we use theory to elucidate the mechanisms by which the vibration may enhance the transport of ions in the electrolyte solution and support the formation of dents in the anode, which was observed in experiment. We find that in the limit of weak ion convection the transport of ions mainly supports the formation of dents in the anode. However, in the limit of prominent ion convection we find an appreciable contribution of the vibration to the efficiency of the electropolishing process, in accordance with the previous experimental findings. The contribution of the vibration to ion transport is given by 2√PeDkC s /π√π, in which the Pecl ́et number, Pe, quantifies the ratio between the convective and diffusive fluxes of ions, and D, k, and C s are the diffusion coefficient of the ions, the wavenumber of the vibration, and the solubility limit of the ions in the electrolyte.