This paper presents a new approach for characterizing heat sealing processes in packaging machines, which identifies all appropriate and optimum sealing parameters subject to given quality criteria. The presented approach is distinct from established methods, such as heat seal curves or response surface plots, in three aspects: It provides an easy-to-read chart indicating optimum and appropriate settings of sealing temperature and dwell time, as well as process robustness for each parameter set. The data points of the charts are generated directly from experiments without using any regression model. The design of experiments features a determinate sequence of tests and no iterative loops are necessary. The approach stems from a ‘trade-off’ model of heat sealing and a specific multi-objective optimization method. This trade-off model states that improving seam quality, reducing sealing temperature, reducing dwell time, and increasing process robustness are conflicting objectives. This hypothesis is deduced from a literature review and verified by experiments. The optimization method claims that all optimum sealing parameters are part of the solution of a multi-objective optimization problem, the Pareto-frontier. This hypothesis is elaborated into a design of experiments using the normal-boundary-intersection method, and is verified using a peelable seam and tear seam scenario.

Die Implementierung und Anwendung von Soil-Vegetation-Atmosphere-Transport-Modellen (SVAT) in der Landwirtschaft erfordert die Kenntnis der aerodynamischen Eigenschaften der Unterlage. Diese sind die Verschiebungslänge d, die Rauhigkeitslänge z0 und weitere Parameter welche den Effekt der Rauhigkeitsschicht unmittelbar über dem Pflanzenbestand beschreiben, wie die Schichthöhen für den Transfer von Impuls Zm* und Skalaren Zs*. Umfangreiche Literaturangaben über einen weiten Bereich von Bestandsmerkmalen wurden zur Entwicklung und Ableitung neuer Schätzfunktionen der genannten Parameter genutzt. Ein neues Modell wird für d als Funktion der Bestandeshöhe hc und dem Plant Area Index PAI vorgeschlagen. Ein semi¬empirisches Vorhersagemodell wird für die Längenskale Ls in Abhängigkeit von hc, PAI, der relativen Kronenhöhe und dem mittleren Abstand zwischen Rauhigkeitselementen entwickelt. Mit Schätzwerten für d, Ls, Zm* und anderen Inputs wurde eine Gleichung für z0 entwickelt und geprüft. Unter Berücksichtigung der Rauhigkeitsschicht werden geschlossene analytische Lösungen für die Schubspannungsgeschwindigkeit, das Windprofil und den aerodynamischen Widerstand präsentiert. Es wird ein Energiebilanzmodell für teilweise mit Folien bedeckten Erddämmen vorgestellt. Bekannte Vorgehensweisen aus der Literatur wurden hinsichtlich der Effekte des peripheren Strahlungsanteils der Sonne, der Modifizierung des kurzwelligen und langwelligen Strahlungstransfers durch den Damm selbst und der winkelabhängigen Transmission und Reflexion von Folien erweitert. Nur 3 Parameter mussten aus stündlichen Messwerten der Bodentemperatur über einen Monat bestimmt werden. Beim Gesamttest des Modells zeigte sich eine mittlere quadratische Abweichung zwischen Simulationen und Messungen der Dammtemperatur von 1.5-1.9 K in Abhängigkeit vom Standort. Testsimulationen zeigten, dass für strahlungsundurchlässige Folien eine präzise Darstellung der winkelabhängigen Reflexion nicht notwendig ist. Für transparente Folien sind zur Beschreibung von Transmission und Reflexion auch einfache Ansätze ausreichend. Nur wenige Inputs sind zur Simulation erforderlich wie die Gehalte an Humus, Sand und Ton, die Dammgeometrie und die Transmissions- und Reflexionsgrade der eingesetzten Folien. / Implementation and application of Soil Vegetation Atmosphere Transport Models (SVAT) in agriculture require knowledge of aerodynamic properties of the exchanging surface. These are the zero plane displacement d, the roughness length for momentum z0, and additional parameters describing the roughness layer just above the canopy as the height of the roughness layer for momentum and scalars (Zm*, Zs*), and parameters of the modified diffusivity profile functions. Several data summaries from the literature on aerodynamic properties over a broad range of plant canopies are used to develop and test predictive models for a number of needed aerodynamic parameters. A new model for d is presented as a function of canopy height hc and Plant Area Index PAI. A semi-empirical equation for the canopy length scale Ls is derived from hc, PAI, fractional crown height, and inter-element spacing of roughness elements. Having estimates of d, Ls, Zm* and other inputs one can derive predictive equations for z0. Closed form analytical expressions are given for the friction velocity, the horizontal wind speed profile and the aerodynamic resistance, which account for both stability and roughness layer effects. An energy balance model for a two-dimensional ridge surface partly covered by a plastic mulch is presented. Previous approaches are modified and extended to include (1) the circumsolar part of diffuse radiation and (2) the altered interception of diffuse short- and long-wave radiation due to horizon obstructions and surface slope and (3) the directional dependence of transmissivity and reflectivity of plastic mulches. Only three parameters had to be estimated from data taken over one month at one site. Overall, simulated data fitted with the whole data set on soil temperatures, with root mean square errors of 1.5 K and 1.9 K for both sites, respectively. Test simulations established that for opaque plastics, detailed analysis of directional radiative properties is not necessary, and for transparent plastics, rather simpler approaches are sufficient. Only a few inputs have to be provided to apply the model: the soil humus content and texture, the shape of the ridge, and the transmissivities and reflectivities of the used plastic mulches in the short-wave and long-wave range.

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Particle-based films are today an important part of various designs and they are implemented in structures as conductive parts, i.e., conductive paste printing in the manufacture of Li-ion batteries, solar cells or resistive paste printing in IC. Recently, particle based films were also implemented in the 3D printing technique, and are particularly important for use in aircraft, wind power, and the automotive industry when incorporated onto the surface of composite structures for protection against damages caused by a lightning strike. A crucial issue for the lightning protection area is to realize films with high homogeneity of electrical resistance where an in-situ noninvasive method has to be elaborated for quality monitoring to avoid undesirable financial and time costs. In this work the drying process of particle based films was investigated by high-frequency eddy current (HFEC) spectroscopy in order to work out an automated in-situ quality monitoring method with a focus on the electrical resistance of the films. Different types of particle based films deposited on dielectric and carbon fiber reinforced plastic substrates were investigated in the present study and results show that the HFEC method offers a good opportunity to monitor the overall drying process of particle based films. Based on that, an algorithm was developed, allowing prediction of the final electrical resistance of the particle based films throughout the drying process, and was successfully implemented in a prototype system based on the EddyCus® HFEC device platform presented in this work. This prototype is the first solution for a portable system allowing HFEC measurement on huge and uneven surfaces.

Particle-based films are today an important part of various designs and they are implemented in structures as conductive parts, i.e., conductive paste printing in the manufacture of Li-ion batteries, solar cells or resistive paste printing in IC. Recently, particle based films were also implemented in the 3D printing technique, and are particularly important for use in aircraft, wind power, and the automotive industry when incorporated onto the surface of composite structures for protection against damages caused by a lightning strike. A crucial issue for the lightning protection area is to realize films with high homogeneity of electrical resistance where an in-situ noninvasive method has to be elaborated for quality monitoring to avoid undesirable financial and time costs. In this work the drying process of particle based films was investigated by high-frequency eddy current (HFEC) spectroscopy in order to work out an automated in-situ quality monitoring method with a focus on the electrical resistance of the films. Different types of particle based films deposited on dielectric and carbon fiber reinforced plastic substrates were investigated in the present study and results show that the HFEC method offers a good opportunity to monitor the overall drying process of particle based films. Based on that, an algorithm was developed, allowing prediction of the final electrical resistance of the particle based films throughout the drying process, and was successfully implemented in a prototype system based on the EddyCus® HFEC device platform presented in this work. This prototype is the first solution for a portable system allowing HFEC measurement on huge and uneven surfaces.

Innerhalb des Forschungsprojekts “InduRex” sollen u.a. dünnwandige Graphit-Polymer Bipolarplatten (BPP) für Brennstoffzellen (BZ) entwickelt werden. Der Fokus liegt dabei auf hochgefüllten Compoundmaterialien und Prozesstechniken zur kontinuierlichen Herstellung dünnwandiger Folien. Dabei wird die gesamte Prozesskette, beginnend von der Auswahl der verwendeten Rohstoffe, über die Folienherstellung bis hin zur Einbringung der erforderlichen Strukturen betrachtet. Die vom „Department of Energy“ festgelegten physikalischen und chemischen Zielwerte werden auch für die Folien als Zielvorgabe gesetzt. Der Schwerpunkt der wissenschaftlichen Arbeit liegt auf einem grundlegenden Verständnis der Materialzusammensetzung und deren Zusammenhang mit den endgültigen Eigenschaften der strukturierten Bipolarplatten, sowie deren Leistung in einem Brennstoffzellenstapel. Die hergestellten Bipolarplattenfolien wurden vor einem Zelltest umfassend hinsichtlich elektrischer Widerstände, H2-Permeation, Warmformbeständigkeit u.a. charakterisiert, um den Einfluss des Produktionsprozesses auf ihre Qualität zu bewerten. / Within the research project 'InduRex', thin-walled graphite-polymer bipolar plates (BPP) for fuel cells (FC) are to be developed, among other things. The focus is on highly filled compound materials and process technologies for the continuous production of thin-walled foils. The entire process chain, starting with the selection of the raw materials used, through film production, to the insertion of the required structures, will be considered. The physical and chemical target values defined by the 'Department of Energy' are also set as targets for the films. The focus of the scientific work is on a fundamental understanding of the material composition and its relationship to the final properties of the patterned bipolar plates, as well as their performance in a fuel cell stack. The fabricated bipolar plate films were extensively characterized in terms of electrical resistances, H2 permeation, heat deflection temperature, and others prior to a cell test to evaluate the impact of the production process on their quality.