The design of efficient positioning algorithms in navigation satellite systems, like GNSS, operating in land mobile environments demands for detailed models of the radio channel. On the one hand, the models need to accurately describe scattering and shadowing/obstruction caused by vegetation. On the other hand, they have to incorporate the steady change in the propagation constellation due to the receiver displacement. In this paper we propose a model of the non-stationary radio channel in a scenario where a mobile receiver drives past a scattering volume, such as a ball or a cuboid, while the transmitter is elevated, like in satellite positioning applications. Such a volume may represent the canopy of a single tree, the canopies of trees in a grove, or a small forest. Scattering by the volume is characterized by means of multiple point-source scatterers that are assumed to form a marked spatial point process. The system functions of the radio channel are given. An integral form of the time-frequency correlation function of the component in the system functions contributed by the scattering volume is obtained as a direct consequence of Campbell's Theorem. Furthermore, a closed-form approximation of this integral form is derived for time lags corresponding to displacements along the receiver trajectory for which the plane wave assumption holds. The approximation takes into account the steady change in the propagation constellation. The proposed model is validated by means of Monte Carlo simulations and by comparing its prediction capabilities with experimental data in a scenario where a mobile receiver drives past a roadside tree. A good agreement is observed, despite the simplicity of the model.

The processing of Binary Offset Carrier (BOC) signals as transmitted by current Global Navigation Satellite Systems (GNSSs) offers potentially better tracking accuracy and a higher multipath rejection. Yet, the presence of multiple peaks of the BOC signals' auto-correlation functions (acfs) results in multiple stable but false tracking points in addition to the correct lock position of the correlation function's main peak. We propose a tracking technique which tracks the subcarrier component of the BOC signal and uses the code component to decide whether or not the correct peak of the correlation function is tracked. The performance is compared to the Bump Jumping and Double Estimator methods in terms of the impact of an emulated front-end filter, continuous wave and chirp interfering signals, forced locks to false peaks, and the multipath envelope. The tests are performed using BOC(1,1) and BOC _cos (15,2.5) signals.

The following chapter deals with scanning acoustic microscopy, a laboratory based high-precision ultrasonic NDE method for detailed investigations of the inner structure of solid materials and components. At the beginning, a short introduction into acoustic microscopy and its preferences is given. In part 2, the basics of ultrasonic wave propagation in an acoustic microscope are explained in terms of wave front snapshots calculated by numerical simulations. In part 3, the typical instrumentation of a Scanning Acoustic Microscope (SAM) used in NDE is presented and some common applications are briefly discussed. In part 4, a comprehensive case study on SAM of resistance spot welding is presented, an exemplary and highly relevant application especially for the automotive industry. In the last two parts of this chapter, advanced imaging techniques for larger depths are presented, the first one based on a SAM adapted implementation of the 3D-SAFT algorithm (Synthetic Aperture Focusing Technique) and the second one using a specific transducer geometry with outstanding performance, a conical annular array.

Piezoelectric 1-3 composite material sensors are used in phased array ultrasonic testing systems. The Dice-and-Fill technique is a very flexible method to fabricate these materials for frequencies up to 10 MHz. A polarized PZT plate is cut in two directions with a dicing saw to separate the PZT pillars. The pitch of the microstructure has to be finer with increasing center frequency to suppress spurious modes. Square shaped pillars with a width of 55 mum, a distance of 30 mum and a height of more than 500 mum are realized. The required times for the dicing process and the number of defects afterwards are compared for various materials. Additionally the usability of ceramic materials for mechanical dicing is evaluated. After the dicing process the structure is filled with a passive polymer, grinded and metalized by physical vapor deposition. The different mechanical and thermal properties of the PZT ceramic and the epoxy filling result in high demands on the electrical interconnection of the composite material. Different methods are investigated. It shows that hot bar soldering is most suitable. A soldering process based on SnBi solder is optimized.

Softness is one of the essential properties of hygiene tissue products. Reliably measuring it is of utmost importance to ensure the balance between customer expectations and cost-effective tissue production. This study presents a method for assessing softness by analyzing acoustic emissions produced while tearing a tissue specimen. The aim was to train neural network models using the corrected results of human panel tests as the ground truth labels and to predict the tissue softness in two- and three-class recognition tasks. We also investigate the possibility of predicting some production parameters related to the softness property. The results proved that tissue softness and production parameters could be reliably estimated only by the tearing noise.