Periodic elastic composite structures attract great attention. They offer the ability to design artificial properties to advance the control over the propagation of elastic/acoustic waves. In previous work, we drew attention to composite periodic structures comprising liquids. It was shown that the transmission spectrum of the structure, specifically a well-isolated peak, follows the material properties of liquid constituent in a distinct manner. This idea was realized in several liquid sensor concepts that launched the field of phononic crystal liquid sensors. In this work we introduce a novel concept—narrow band solid-liquid composite arrangements. We demonstrate two different concepts to design narrow band structures, and show the results of theoretical studies and results of experimental investigations that confirm the theoretical predictions. This work extends prior studies in the field of phononic crystal liquid sensors with novel concepts and results that have a high potential in a field of volumetric liquid properties evaluation.

The focus of this paper is the operation of magnetically controlled shunt reactors in high voltage electrical grids and their role as sources of current and voltage harmonics. Power quality measurements on real-life controlled reactors show that these machines are largely responsible for voltage waveform distortion with voltage total harmonic distortion overshooting permissible limits in the points of coupling to electrical grid. A simulation model of a magnetically controlled shunt reactor has been developed and verified using field test results. Main factors influencing reactor impact on voltage waveform distortion are examined, and possible limits of such impact are estimated.

Fluidized bed layering granulation is frequently used to formulate particles of high quality. From previous studies, it is well known that the dynamic behavior of the process, as well as the product properties depend on operating parameters. The process is characterized by heat and mass transfer between fluidized particles and the surrounding fluidization medium. To investigate the mutual influence between particle phase and fluidization medium, a dynamic model is introduced. The model comprises two parts: a population balance model to describe the evolution of the particle sizes and a system of ordinary differential equations to account for thermal conditions. For the first time, the dynamic model considers the bidirectional coupling of particles and fluidization medium in fluidized bed layering granulation. By means of simulations, it is shown that the derived model is capable of reproducing the experimental findings.

Agglomeration represents an important particle formation process used in many industries. One particularly attractive process setup is continuous fluidized bed spray agglomeration, which features good mixing as well as high heat and mass transfer on the one hand and constant product throughput with constant quality as well as high flow rates compared to batch mode on the other hand. Particle properties such as agglomerate size or porosity significantly affect overall product properties such as re-hydration behavior and dissolubility. These can be influenced by different operating parameters. In this manuscript, a population balance model for a continuous fluidized bed spray agglomeration is presented and adapted to experimental data. Focus is on the description of the dynamic behavior in continuous operation mode in a certain neighborhood around steady-state. Different kernel candidates are evaluated and it is shown that none of the kernels are able to match the first six minutes with time independent parameters. Afterwards, a good fit can be obtained, where the Brownian and the volume independent kernel models match best with the experimental data. Model fit is improved for identification on a shifted time domain neglecting the initial start-up phase. Here, model identifiability is shown and parameter confidence intervals are computed via parametric bootstrap.

Zusammenfassung: Der Beitrag beschreibt einen neuen Regelungsansatz zur Stabilisierung von Kristallisatoren. Es ist bekannt, dass diese in Verbindung mit einer Feinkornauflösung zu Instabilitäten und dem Auftreten von unerwünschten Oszillationen neigen. Modelle für Kristallisatoren bestehen meist aus einer nichtlinearen partiellen Integrodifferentialgleichung, der Populationsbilanz für die Kristallgrößenverteilung, gekoppelt mit einer gewöhnlichen Differentialgleichung zur Beschreibung der flüssigen Phase, was einen rigorosen Reglerentwurf vor erhebliche Probleme stellt. Deshalb wird im Rahmen dieser Arbeit auf ein Stabilitätskonzept zurückgegriffen, welches Aussagen über die Stabilität eines Prozesses bezüglich zweier verallgemeinerter Abstandmaße, den sogenannten Diskrepanzen, erlaubt.