The gas phase infrared and fragmentation spectra of a systematic group of trimetallic oxo-centered transition metal complexes are shown and discussed, with formate and acetate bridging ligands and pyridine and water as axial ligands. The stability of the complexes, as predicted by appropriate ab initio simulations, is demonstrated to agree with collision induced dissociation (CID) measurements. A broad range of DFT calculations are shown. They are used to simulate the geometry, the bonding situation, relative stability and flexibility of the discussed complexes, and to specify the observed trends. These simulations correctly predict the trends in the band splitting of the symmetric and asymmetric carboxylate stretch modes, but fail to account for anharmonic effects observed specifically in the mid IR range. The infrared spectra of the different ligands are introduced in a brief literature review. Their changes in different environments or different bonding situations are discussed and visualized, especially the interplay between fundamental-, overtone-, and combination bands, as well as Fermi resonances between them. A new variation on the infrared multi photon dissociation (IRMPD) spectroscopy method is proposed and evaluated. In addition to the commonly considered total fragment yield, the cumulative fragment yield can be used to plot the wavelength dependent relative abundance of different fragmentation products. This is shown to include valuable additional information on the excited chromophors, and their coupling to specific fragmentation channels. High quality homo- and heterometallic IRMPD spectra of oxo centered carboxylate complexes of chromium and iron show the impacts of the influencing factors: the metal centers, the bridging ligands, their carboxylate stretch modes and CH bend modes, and the terminal ligands. In all four formate spectra, anharmonic effects are necessary to explain the observed spectra: combination bands of both carboxylate stretch modes and a Fermi resonance of the fundamental of the CH stretch mode, and a combination band of the asymmetric carboxylate stretch mode with the CH bend mode of the formate bridging ligand. For the water adduct species, partial hydrolysis is proposed to account for the changes in the observed carboxylic stretch modes. Appropriate experiments are suggested to verify the mode assignments that are not directly explained by the ab initio calculations, the available experimental results or other means like deuteration experiments.

Faser-Kunststoff-Verbunde (FKV) sind in der Luftfahrt etabliert, wohingegen andere Branchen diese aufgrund der hohen Kosten nur zögerlich einsetzen. Die hohen Betriebskosten von Flugzeugen, die sich vorrangig durch Leichtbau reduzieren lassen, erlauben kostenintensivere Lösungen als die Kostenstrukturen in anderen Branchen. Die Mehrkosten sind neben dem Leichtbau der entscheidende Faktor für den Einsatz von FKV-Strukturen außerhalb der Luftfahrtbranche. Während in der Luftfahrtbranche üblicherweise Niete zur Krafteinleitung eingesetzt werden und diese nur eine Demontage eines Bauteils durch Aufbohren zulassen, genügen Niete den Ansprüchen anderer Branchen nicht, da ein hoher Demontageaufwand durch das Aufbohren hohe Kosten mit sich zieht. Aus diesem Grund erfordert es preisgünstige und qualitative Lösungen, die eine lösbare Verbindung ermöglichen. In den meisten Branchen werden daher, im Gegensatz zur Luftfahrt, traditionell reibschlüssige Schraubenverbindungen für metallische Bauteile verwendet. Für reibschlüssige Schraubenverbindungen, die zur Krafteinleitung in FKV-Strukturen genutzt werden, sind dem Stand der Forschung nach kaum Erkenntnisse vorhanden. Daher ist es Gegenstand dieser Arbeit aufzuzeigen, wie durch eine Erhöhung des Reibwerts bei reibschlüssigen Krafteinleitungen in FKV-Bauteilen eine Verbesserung der statischen und zyklischen Verbindungsfestigkeit erreicht werden kann. Um den zuverlässigen Einsatz von reibschlüssigen Schraubenverbindungen zu ermöglichen, werden außerdem die maximal zulässige Flächenpressung und der Vorspannkraftverlust an FKV-Proben ermittelt. Dabei bilden experimentelle Ergebnisse eine Basis, anhand derer aufgezeigt wird, inwieweit analytische Modelle genutzt werden können,um die reibschlüssige Krafteinleitung in FKV abzubilden. Zunächst wird der Haftreibwert zwischen Stahl und FKV experimentell untersucht, um Konzepte zur Steigerung des Reibwerts zu quantifizieren. Durch die experimentelle Ermittlung einer maximal zulässigen Flächenpressung für die verwendeten FKVMaterialien werden Schädigungen infolge zu hoher Vorspannkräfte vermieden. Dazu werden FKV- Proben mit einem Stempel belastet und mit Hilfe der Schallemissionsmethode Schädigungen detektiert, zu dem Zweck eine Belastungsgrenze zu definieren. Versuche zur Bestimmung des Vorspannkraftverlusts an FKV-Proben zeigen, dass die Vorspannkraft durch Setzen und Kriechen zwar reduziert wird, dies aber in vertretbarem Maße. Darüber hinaus lässt sich in den Versuchen beobachten, dass das Setzen deutlich von der Oberflächenbeschaffenheit bestimmt wird. Um die Einflüsse des Matrixwerkstoffs, des Reibwerts, der Passung und der Vorspannkraft auf die Kraftübertragung in der Schraubverbindung zu prüfen, werden außerdem doppellaschige Zugscherversuche durchgeführt. An geklemmten FKV-Bauteilen im Fahrradbau lassen sich Defizite bei der Auslegung dieser Bauteile und ihrer Anbindungstechnologie feststellen. Da der Verbindung zwischen Vorbau und Gabelschaft besondere sicherheitsrelevante Bedeutung zukommt, wird eine marktübliche Gabelschaft-Vorbau-Klemmung im Rahmen dieser Arbeit experimentell und numerisch auf die Belastungen durch die Montage sowie im Betrieb untersucht. Es kann dargelegt werden, dass ein komplexer Belastungszustand in der genannten Klemmverbindung vorliegt, der numerisch abgebildet werden kann. Auf Basis des validierten Finite-Element-Modells kann gezeigt werden, dass die Steigerung des Reibwerts ein deutliches Potential aufweist um die Werkstoffanstrengung zu reduzieren. Zur experimentellen Absicherung dieser Beobachtung, werden quasistatische und zyklische Untersuchungen an Vorbau-Gabelschaft-Baugruppen durchgeführt, bei denen der Reibwert durch die Applikation von Schmierfett und Carbonmontagepaste variiert wird. Durch die Verwendung von Carbonmontagepaste bzw. bei einem höheren Reibwert steigt sowohl die quasi-statische Festigkeit als auch die Lebensdauer im Vergleich zum Einsatz von Schmierfett deutlich an. Fiber reinforced plastics (FRP) are well established materials in the aviation industry, whereas in other industries these materials are not yet this commonly used due to the comparatively high costs. The high operating costs of aircrafts can be reduced primarily through lightweight design, which allows the choice of more expensive solutions than in other industries. The additional costs are beside the weight savings the deciding factor for the use of FRP structures beyond the aviation sector. Since normally rivets are used in the aviation industry to join components, the dismantling of these riveted structures needs drilling. Hence rivets are insufficient for the demands of other sectors due to the high disassembly costs caused by the high disassembly effort. For this reason affordable solutions that permit an easy disassembly procedure are essential for a wider application of FRP structures. Therefore – in most sectors – preloaded bolted joints are used for the assembly of metallic components, in contrast to aviation. For preloaded bolted joints in combination with FRP structures almost no information is available by the current state of scientific knowledge Therefore in this work it is investigated how an improvement of the static and cyclic connection strength can be achieved by increasing the coefficient of friction at preloaded bolted joints on FRP components. To enable a reliable application of preloaded bolted joints the maximum allowable surface pressure and the loss of the preload force of FRP specimens are determined. Therefore experimental results provide the basis to study if analytical computation can be used to describe bolted joints on FRP structures. The coefficient of friction between steel and FRP is experimentally investigated in order to quantify concepts that aim to increase the coefficient of friction. An experimental determination of the maximum permissible surface pressure of the used FRP materials avoids damage by excessive bolt preload. Therefore FRP specimens are tested and a simultaneous detection of damage is performed by using the acoustic emission method. An experimentalinvestigation of the loss of bolt preload shows that the preload is reduced by embedding and material relaxation but in an acceptable manner. In addition it can be observed that the embedding of the contact surfaces is significantly dependent on the surface condition of the specimens. To analyze the influence of the matrix material, the coefficient of friction, the clearance and the bolt preload to a bolted joint, double lap tensile shear tests are performed. Clamped FRP components used on bicycles show shortcomings in the design of these components and their connection technology. Since the connection between stem and steerer has a significant impact on safety, a standard stem/steerer connection is investigated both experimentally and numerically considering the stresses during the assembling as well as during operation. It can be demonstrated that this connection has a complex load condition and a finite element analysis can describe this connection sufficiently. Based on the validated finite element model it can be shown that an increasing coefficient of friction has a significant potential for the reduction of the material effort of the FRP steerer. To validate these theoretical observations, quasi-static and cyclic tests on stem/steerer assemblies are carried out. Thereby the coefficient of friction is varied by the application of grease and carbon assembly paste. By the use of carbon assembly paste (high coefficient of friction) both the quasi-static strength as well as the operating life increases in comparison to the use of grease (low coefficient of friction).

Destructive diseases of the lung like lung cancer or fibrosis are still often lethal. Also in case of fibrosis in the liver, the only possible cure is transplantation. In this thesis, we investigate 3D micro computed synchrotron radiation (SR\( \mu \)CT) images of capillary blood vessels in mouse lungs and livers. The specimen show so-called compensatory lung growth as well as different states of pulmonary and hepatic fibrosis. During compensatory lung growth, after resecting part of the lung, the remaining part compensates for this loss by extending into the empty space. This process is accompanied by an active vessel growing. In general, the human lung can not compensate for such a loss. Thus, understanding this process in mice is important to improve treatment options in case of diseases like lung cancer. In case of fibrosis, the formation of scars within the organ's tissue forces the capillary vessels to grow to ensure blood supply. Thus, the process of fibrosis as well as compensatory lung growth can be accessed by considering the capillary architecture. As preparation of 2D microscopic images is faster, easier, and cheaper compared to SR\( \mu \)CT images, they currently form the basis of medical investigation. Yet, characteristics like direction and shape of objects can only properly be analyzed using 3D imaging techniques. Hence, analyzing SR\( \mu \)CT data provides valuable additional information. For the fibrotic specimen, we apply image analysis methods well-known from material science. We measure the vessel diameter using the granulometry distribution function and describe the inter-vessel distance by the spherical contact distribution. Moreover, we estimate the directional distribution of the capillary structure. All features turn out to be useful to characterize fibrosis based on the deformation of capillary vessels. It is already known that the most efficient mechanism of vessel growing forms small torus-shaped holes within the capillary structure, so-called intussusceptive pillars. Analyzing their location and number strongly contributes to the characterization of vessel growing. Hence, for all three applications, this is of great interest. This thesis provides the first algorithm to detect intussusceptive pillars in SR\( \mu \)CT images. After segmentation of raw image data, our algorithm works automatically and allows for a quantitative evaluation of a large amount of data. The analysis of SR\( \mu \)CT data using our pillar algorithm as well as the granulometry, spherical contact distribution, and directional analysis extends the current state-of-the-art in medical studies. Although it is not possible to replace certain 3D features by 2D features without losing information, our results could be used to examine 2D features approximating the 3D findings reasonably well.

In Anbetracht leistungsschwacher öffentlicher Institutionen im subsaharischen Afrika formulierte die Weltbank in den neunziger Jahren ein Anforderungsprofil an den Staat und die öffentliche Verwaltung. Sie führte wesentliche Ursachen für die sozialen und ökonomischen Fehlentwicklungen im subsaharischen Afrika auf Defizite im institutionellen Umfeld von Staat und Verwaltung zurück. In der Folgezeit avancierte dieses Anforderungsprofil zum entwicklungspolitischen Leitbild des Good Governance. Heute bildet das Thema einen elementaren Bereich der internationalen Entwicklungszusammenarbeit und einen zentralen Aspekt der entwicklungspolitischen Auseinandersetzung. Insbesondere die unterschiedlichen Auffassungen darüber, inwiefern Demokratisierungsforderungen mit dem Leitbild des Good Governance verknüpft werden sollten, sind immer wieder Gegenstand der wissenschaftlichen und der politischen Diskussion. Deutlich kommt in diesem Zusammenhang die Streitfrage zum Ausdruck, ob die Entwicklung eines Staates Demokratie voraussetzt oder ob die Demokratie umgekehrt vielmehr ein Ergebnis erfolgreicher Entwicklungsprozesse darstellt. Es ist anzumerken, dass die Entwicklungsforschung diese Frage bislang nicht widerspruchsfrei erklären konnte. Darüber hinaus sprechen zahlreiche Länderbeispiele vielmehr dafür, dass die Staatsform grundsätzlich nicht die entscheidende Variable bildet, um klare Erkenntnisse für die Begründung ökonomischen Wachstums bzw. für die Erfolge der Armutsbekämpfung abzuleiten. Es erscheint zunächst folgerichtig, dass die Weltbank in Bezug auf Good Governance keine Demokratisierungsforderungen stellt. In der vorliegenden Ausarbeitung wird vor diesem Hintergrund untersucht, inwiefern sich die Staatsform eines Landes auf die Existenz der jeweiligen Prinzipien für Good Governance auswirkt. Anhand zweier ökonomisch erfolgreicher afrikanischer Länder wird analysiert, inwiefern entwicklungsförderliche Good Governance-Strukturen unabhängig von der jeweils vorherrschenden Staatsform existieren können. Methodisch wird dabei das Anforderungsprofil der Weltbank auf die Demokratie Mauritius und auf die Autokratie Ruanda angewendet.

The growing computational power enables the establishment of the Population Balance Equation (PBE) to model the steady state and dynamic behavior of multiphase flow unit operations. Accordingly, the twophase flow behavior inside liquid-liquid extraction equipment is characterized by different factors. These factors include: interactions among droplets (breakage and coalescence), different time scales due to the size distribution of the dispersed phase, and micro time scales of the interphase diffusional mass transfer process. As a result of this, the general PBE has no well known analytical solution and therefore robust numerical solution methods with low computational cost are highly admired. In this work, the Sectional Quadrature Method of Moments (SQMOM) (Attarakih, M. M., Drumm, C., Bart, H.-J. (2009). Solution of the population balance equation using the Sectional Quadrature Method of Moments (SQMOM). Chem. Eng. Sci. 64, 742-752) is extended to take into account the continuous flow systems in spatial domain. In this regard, the SQMOM is extended to solve the spatially distributed nonhomogeneous bivariate PBE to model the hydrodynamics and physical/reactive mass transfer behavior of liquid-liquid extraction equipment. Based on the extended SQMOM, two different steady state and dynamic simulation algorithms for hydrodynamics and mass transfer behavior of liquid-liquid extraction equipment are developed and efficiently implemented. At the steady state modeling level, a Spatially-Mixed SQMOM (SM-SQMOM) algorithm is developed and successfully implemented in a onedimensional physical spatial domain. The integral spatial numerical flux is closed using the mean mass droplet diameter based on the One Primary and One Secondary Particle Method (OPOSPM which is the simplest case of the SQMOM). On the other hand the hydrodynamics integral source terms are closed using the analytical Two-Equal Weight Quadrature (TEqWQ). To avoid the numerical solution of the droplet rise velocity, an analytical solution based on the algebraic velocity model is derived for the particular case of unit velocity exponent appearing in the droplet swarm model. In addition to this, the source term due to mass transport is closed using OPOSPM. The resulting system of ordinary differential equations with respect to space is solved using the MATLAB adaptive Runge–Kutta method (ODE45). At the dynamic modeling level, the SQMOM is extended to a one-dimensional physical spatial domain and resolved using the finite volume method. To close the mathematical model, the required quadrature nodes and weights are calculated using the analytical solution based on the Two Unequal Weights Quadrature (TUEWQ) formula. By applying the finite volume method to the spatial domain, a semi-discreet ordinary differential equation system is obtained and solved. Both steady state and dynamic algorithms are extensively validated at analytical, numerical, and experimental levels. At the numerical level, the predictions of both algorithms are validated using the extended fixed pivot technique as implemented in PPBLab software (Attarakih, M., Alzyod, S., Abu-Khader, M., Bart, H.-J. (2012). PPBLAB: A new multivariate population balance environment for particulate system modeling and simulation. Procedia Eng. 42, pp. 144-562). At the experimental validation level, the extended SQMOM is successfully used to model the steady state hydrodynamics and physical and reactive mass transfer behavior of agitated liquid-liquid extraction columns under different operating conditions. In this regard, both models are found efficient and able to follow liquid extraction column behavior during column scale-up, where three column diameters were investigated (DN32, DN80, and DN150). To shed more light on the local interactions among the contacted phases, a reduced coupled PBE and CFD framework is used to model the hydrodynamic behavior of pulsed sieve plate columns. In this regard, OPOSPM is utilized and implemented in FLUENT 18.2 commercial software as a special case of the SQMOM. The dropletdroplet interactions (breakage and coalescence) are taken into account using OPOSPM, while the required information about the velocity field and energy dissipation is calculated by the CFD model. In addition to this, the proposed coupled OPOSPM-CFD framework is extended to include the mass transfer. The proposed framework is numerically tested and the results are compared with the published experimental data. The required breakage and coalescence parameters to perform the 2D-CFD simulation are estimated using PPBLab software, where a 1D-CFD simulation using a multi-sectional gird is performed. A very good agreement is obtained at the experimental and the numerical validation levels.