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III/V semiconductor quantum dots (QD) are in the focus of optoelectronics research for about 25 years now. Most of the work
has been done on InAs QD on GaAs substrate. But, e.g., Ga(As)Sb (antimonide) QD on GaAs substrate/buffer have also gained
attention for the last 12 years.There is a scientific dispute on whether there is a wetting layer before antimonide QD formation, as
commonly expected for Stransky-Krastanov growth, or not. Usually ex situ photoluminescence (PL) and atomic force microscope
(AFM) measurements are performed to resolve similar issues. In this contribution, we show that reflectance anisotropy/difference
spectroscopy (RAS/RDS) can be used for the same purpose as an in situ, real-time monitoring technique. It can be employed not
only to identify QD growth via a distinct RAS spectrum, but also to get information on the existence of a wetting layer and its
thickness. The data suggest that for antimonide QD growth the wetting layer has a thickness of 1 ML (one monolayer) only.
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.
Numerical Godeaux surfaces are minimal surfaces of general type with the smallest possible numerical invariants. It is known that the torsion group of a numerical Godeaux surface is cyclic of order \(m\leq 5\). A full classification has been given for the cases \(m=3,4,5\) by the work of Reid and Miyaoka. In each case, the corresponding moduli space is 8-dimensional and irreducible.
There exist explicit examples of numerical Godeaux surfaces for the orders \(m=1,2\), but a complete classification for these surfaces is still missing.
In this thesis we present a construction method for numerical Godeaux surfaces which is based on homological algebra and computer algebra and which arises from an experimental approach by Schreyer. The main idea is to consider the canonical ring \(R(X)\) of a numerical Godeaux surface \(X\) as a module over some graded polynomial ring \(S\). The ring \(S\) is chosen so that \(R(X)\) is finitely generated as an \(S\)-module and a Gorenstein \(S\)-algebra of codimension 3. We prove that the canonical ring of any numerical Godeaux surface, considered as an \(S\)-module, admits a minimal free resolution whose middle map is alternating. Moreover, we show that a partial converse of this statement is true under some additional conditions.
Afterwards we use these results to construct (canonical rings of) numerical Godeaux surfaces. Hereby, we restrict our study to surfaces whose bicanonical system has no fixed component but 4 distinct base points, in the following referred to as marked numerical Godeaux surfaces.
The particular interest of this thesis lies on marked numerical Godeaux surfaces whose torsion group is trivial. For these surfaces we study the fibration of genus 4 over \(\mathbb{P}^1\) induced by the bicanonical system. Catanese and Pignatelli showed that the general fibre is non-hyperelliptic and that the number \(\tilde{h}\) of hyperelliptic fibres is bounded by 3. The two explicit constructions of numerical Godeaux surfaces with a trivial torsion group due to Barlow and Craighero-Gattazzo, respectively, satisfy \(\tilde{h} = 2\).
With the method from this thesis, we construct an 8-dimensional family of numerical Godeaux surfaces with a trivial torsion group and whose general element satisfy \(\tilde{h}=0\).
Furthermore, we establish a criterion for the existence of hyperelliptic fibres in terms of a minimal free resolution of \(R(X)\). Using this criterion, we verify experimentally the
existence of a numerical Godeaux surface with \(\tilde{h}=1\).
In this article a new numerical solver for simulations of district heating networks is presented. The numerical method applies the local time stepping introduced in [11] to networks of linear advection equations. In combination with the high order approach of [4] an accurate and very efficient scheme is developed. In several numerical test cases the advantages for simulations of district heating networks are shown.
1,3-Diynes are frequently found as an important structural motif in natural products, pharmaceuticals and bioactive compounds, electronic and optical materials and supramolecular molecules. Copper and palladium complexes are widely used to prepare 1,3-diynes by homocoupling of terminal alkynes; albeit the potential of nickel complexes towards the same is essentially unexplored. Although a detailed study on the reported nickel-acetylene chemistry has not been carried out, a generalized mechanism featuring a nickel(II)/nickel(0) catalytic cycle has been proposed. In the present work, a detailed mechanistic aspect of the nickel-mediated homocoupling reaction of terminal alkynes is investigated through the isolation and/or characterization of key intermediates from both the stoichiometric and the catalytic reactions. A nickel(II) complex [Ni(L-N4Me2)(MeCN)2](ClO4)2 (1) containing a tetradentate N,N′-dimethyl-2,11-diaza[3.3](2,6)pyridinophane (L-N4Me2) as ligand was used as catalyst for homocoupling of terminal alkynes by employing oxygen as oxidant at room temperature. A series of dinuclear nickel(I) complexes bridged by a 1,3-diyne ligand have been isolated from stoichiometric reaction between [Ni(L-N4Me2)(MeCN)2](ClO4)2 (1) and lithium acetylides. The dinuclear nickel(I)-diyne complexes [{Ni(L-N4Me2)}2(RC4R)](ClO4)2 (2) were well characterized by X-ray crystal structures, various spectroscopic methods, SQUID and DFT calculation. The complexes not only represent as a key intermediate in aforesaid catalytic reaction, but also describe the first structurally characterized dinuclear nickel(I)-diyne complexes. In addition, radical trapping and low temperature UV-Vis-NIR experiments in the formation of the dinuclear nickel(I)-diyne confirm that the reactions occurring during the reduction of nickel(II) to nickel(I) and C-C bond formation of 1,3-diyne follow non-radical concerted mechanism. Furthermore, spectroscopic investigation on the reactivity of the dinuclear nickel(I)-diyne complex towards molecular oxygen confirmed the formation of a mononuclear nickel(I)-diyne species [Ni(L-N4Me2)(RC4R)]+ (4) and a mononuclear nickel(III)-peroxo species [Ni(L-N4Me2)(O2)]+ (5) which were converted to free 1,3-diyne and an unstable dinuclear nickel(II) species [{Ni(L-N4Me2)}2(O2)]2+ (6). A mononuclear nickel(I)-alkyne complex [Ni(L-N4Me2)(PhC2Ph)](ClO4).MeOH (3) and the mononuclear nickel(III)-peroxo species [Ni(L-N4Me2)(O2)]+ (5) were isolated/generated and characterized to confirm the formulation of aforementioned mononuclear nickel(I)-diyne and mononuclear nickel(III)-peroxo species. Spectroscopic experiments on the catalytic reaction mixture also confirm the presence of aforesaid intermediates. Results of both stoichiometric and catalytic reactions suggested an intriguing mechanism involving nickel(II)/nickel(I)/nickel(III) oxidation states in contrast to the reported nickel(II)/nickel(0) catalytic cycle. These findings are expected to open a new paradigm towards nickel-catalyzed organic transformations.
The simulation of cutting process challenges established methods due to large deformations and topological changes. In this work a particle finite element method (PFEM) is presented, which combines the benefits of discrete modeling techniques and methods based on continuum mechanics. A crucial part of the PFEM is the detection of the boundary of a set of particles. The impact of this boundary detection method on the structural integrity is examined and a relation of the key parameter of the method to the eigenvalues of strain tensors is elaborated. The influence of important process parameters on the cutting force is studied and a comparison to an empirical relation is presented.
The authors explore the intrinsic trade-off in a DRAM between the power consumption (due to refresh) and the reliability. Their unique measurement platform allows tailoring to the design constraints depending on whether power consumption, performance or reliability has the highest design priority. Furthermore, the authors show how this measurement platform can be used for reverse engineering the internal structure of DRAMs and how this knowledge can be used to improve DRAM’s reliability.
For modeling approaches in systems biology, knowledge of the absolute abundances of cellular proteins is essential. One way to gain this knowledge is the use of quantification concatamers (QconCATs), which are synthetic proteins consisting of proteotypic peptides derived from the target proteins to be quantified. The QconCAT protein is labeled with a heavy isotope upon expression in E. coli and known amounts of the purified protein are spiked into a whole cell protein extract. Upon tryptic digestion, labeled and unlabeled peptides are released from the QconCAT and the native proteins, respectively, and both are quantified by LC-MS/MS. The labeled Q-peptides then serve as standards for determining the absolute quantity of the native peptides/proteins. Here we have applied the QconCAT approach to Chlamydomonas reinhardtii for the absolute quantification of the major proteins and protein complexes driving photosynthetic light reactions in the thylakoid membranes and carbon fixation in the pyrenoid. We found that with 25.2 attomol/cell the Rubisco large subunit makes up 6.6% of all proteins in a Chlamydomonas cell and with this exceeds the amount of the small subunit by a factor of 1.56. EPYC1, which links Rubisco to form the pyrenoid, is eight times less abundant than RBCS, and Rubisco activase is 32-times less abundant than RBCS. With 5.2 attomol/cell, photosystem II is the most abundant complex involved in the photosynthetic light reactions, followed by plastocyanin, photosystem I and the cytochrome b6/f complex, which range between 2.9 and 3.5 attomol/cell. The least abundant complex is the ATP synthase with 2 attomol/cell. While applying the QconCAT approach, we have been able to identify many potential pitfalls associated with this technique. We analyze and discuss these pitfalls in detail and provide an optimized workflow for future applications of this technique.
If gradient based derivative algorithms are used to improve industrial products by reducing their target functions, the derivatives need to be exact.
The last percent of possible improvement, like the efficiency of a turbine, can only be gained if the derivatives are consistent with the solution process that is used in the simulation software.
It is problematic that the development of the simulation software is an ongoing process which leads to the use of approximated derivatives.
If a derivative computation is implemented manually, it will be inconsistent after some time if it is not updated.
This thesis presents a generalized approach which differentiates the whole simulation software with Algorithmic Differentiation (AD), and guarantees a correct and consistent derivative computation after each change to the software.
For this purpose, the variable tagging technique is developed.
The technique checks at run-time if all dependencies, which are used by the derivative algorithms, are correct.
Since it is also necessary to check the correctness of the implementation, a theorem is developed which describes how AD derivatives can be compared.
This theorem is used to develop further methods that can detect and correct errors.
All methods are designed such that they can be applied in real world applications and are used within industrial configurations.
The process described above yields consistent and correct derivatives but the efficiency can still be improved.
This is done by deriving new derivative algorithms.
A fixed-point iterator approach, with a consistent derivation, yields all state of the art algorithms and produces two new algorithms.
These two new algorithms include all implementation details and therefore they produce consistent derivative results.
For detecting hot spots in the application, the state of the art techniques are presented and extended.
The data management is changed such that the performance of the software is affected only marginally when quantities, like the number of input and output variables or the memory consumption, are computed for the detection.
The hot spots can be treated with techniques like checkpointing or preaccumulation.
How these techniques change the time and memory consumption is analyzed and it is shown how they need to be used in selected AD tools.
As a last step, the used AD tools are analyzed in more detail.
The major implementation strategies for operator overloading AD tools are presented and implementation improvements for existing AD tools are discussed.
The discussion focuses on a minimal memory consumption and makes it possible to compare AD tools on a theoretical level.
The new AD tool CoDiPack is based on these findings and its design and concepts are presented.
The improvements and findings in this thesis make it possible, that an automatic, consistent and correct derivative is generated in an efficient way for industrial applications.
In modern algebraic geometry solutions of polynomial equations are studied from a qualitative point of view using highly sophisticated tools such as cohomology, \(D\)-modules and Hodge structures. The latter have been unified in Saito’s far-reaching theory of mixed Hodge modules, that has shown striking applications including vanishing theorems for cohomology. A mixed Hodge module can be seen as a special type of filtered \(D\)-module, which is an algebraic counterpart of a system of linear differential equations. We present the first algorithmic approach to Saito’s theory. To this end, we develop a Gröbner basis theory for a new class of algebras generalizing PBW-algebras.
The category of mixed Hodge modules satisfies Grothendieck’s six-functor formalism. In part these functors rely on an additional natural filtration, the so-called \(V\)-filtration. A key result of this thesis is an algorithm to compute the \(V\)-filtration in the filtered setting. We derive from this algorithm methods for the computation of (extraordinary) direct image functors under open embeddings of complements of pure codimension one subvarieties. As side results we show
how to compute vanishing and nearby cycle functors and a quasi-inverse of Kashiwara’s equivalence for mixed Hodge modules.
Describing these functors in terms of local coordinates and taking local sections, we reduce the corresponding computations to algorithms over certain bifiltered algebras. It leads us to introduce the class of so-called PBW-reduction-algebras, a generalization of the class of PBW-algebras. We establish a comprehensive Gröbner basis framework for this generalization representing the involved filtrations by weight vectors.
In modern algebraic geometry solutions of polynomial equations are studied from a qualitative point of view using highly sophisticated tools such as cohomology, \(D\)-modules and Hodge structures. The latter have been unified in Saito’s far-reaching theory of mixed Hodge modules, that has shown striking applications including vanishing theorems for cohomology. A mixed Hodge module can be seen as a special type of filtered \(D\)-module, which is an algebraic counterpart of a system of linear differential equations. We present the first algorithmic approach to Saito’s theory. To this end, we develop a Gröbner basis theory for a new class of algebras generalizing PBW-algebras.
The category of mixed Hodge modules satisfies Grothendieck’s six-functor formalism. In part these functors rely on an additional natural filtration, the so-called \(V\)-filtration. A key result of this thesis is an algorithm to compute the \(V\)-filtration in the filtered setting. We derive from this algorithm methods for the computation of (extraordinary) direct image functors under open embeddings of complements of pure codimension one subvarieties. As side results we show how to compute vanishing and nearby cycle functors and a quasi-inverse of Kashiwara’s equivalence for mixed Hodge modules.
Describing these functors in terms of local coordinates and taking local sections, we reduce the corresponding computations to algorithms over certain bifiltered algebras. It leads us to introduce the class of so-called PBW-reduction-algebras, a generalization of the class of PBW-algebras. We establish a comprehensive Gröbner basis framework for this generalization representing the involved filtrations by weight vectors.
Optical Character Recognition (OCR) system plays an important role in digitization of data acquired as images from a variety of sources. Although the area is very well explored for Latin languages, some of the languages based on Arabic cursive script are not yet explored. It is due to many factors: Most importantly are the unavailability of proper data sets and complexities posed by cursive scripts. The Pashto language is one of such languages which needs considerable exploration towards OCR. In order to develop such an OCR system, this thesis provides a pioneering study that explores deep learning for the Pashto language in the field of OCR.
The Pashto language is spoken by more than $50$ million people across the world, and it is an active medium both for oral as well as written communication. It is associated with rich literary heritage and contains huge written collection. These written materials present contents of simple to complex nature, and layouts from hand-scribed to printed text. The Pashto language presents mainly two types of complexities (i) generic w.r.t. cursive script, (ii) specific w.r.t. Pashto language. Generic complexities are cursiveness, context dependency, and breaker character anomalies, as well as space anomalies. Pashto specific complexities are variations in shape for a single character and shape similarity for some of the additional Pashto characters. Existing research in the area of Arabic OCR did not lead to an end-to-end solution for the mentioned complexities and therefore could not be generalized to build a sophisticated OCR system for Pashto.
The contribution of this thesis spans in three levels, conceptual level, data level, and practical level. In the conceptual level, we have deeply explored the Pashto language and identified those characters, which are responsible for the challenges mentioned above. In the data level, a comprehensive dataset is introduced containing real images of hand-scribed contents. The dataset is manually transcribed and has the most frequent layout patterns associated with the Pashto language. The practical level contribution provides a bridge, in the form of a complete Pashto OCR system, and connects the outcomes of the conceptual and data levels contributions. The practical contribution comprises of skew detection, text-line segmentation, feature extraction, classification, and post-processing. The OCR module is more strengthened by using deep learning paradigm to recognize Pashto cursive script by the framework of Recursive Neural Networks (RNN). Proposed Pashto text recognition is based on Long Short-Term Memory Network (LSTM) and realizes a character recognition rate of $90.78\%$ on Pashto real hand-scribed images. All these contributions are integrated into an application to provide a flexible and generic End-to-End Pashto OCR system.
The impact of this thesis is not only specific to the Pashto language, but it is also beneficial to other cursive languages like Arabic, Urdu, and Persian e.t.c. The main reason is the Pashto character set, which is a superset of Arabic, Persian, and Urdu languages. Therefore, the conceptual contribution of this thesis provides insight and proposes solutions to almost all generic complexities associated with Arabic, Persian, and Urdu languages. For example, an anomaly caused by breaker characters is deeply analyzed, which is shared among 70 languages, mainly use Arabic script. This thesis presents a solution to this issue and is equally beneficial to almost all Arabic like languages.
The scope of this thesis has two important aspects. First, a social impact, i.e., how a society may benefit from it. The main advantages are to bring the historical and almost vanished document to life and to ensure the opportunities to explore, analyze, translate, share, and understand the contents of Pashto language globally. Second, the advancement and exploration of the technical aspects. Because, this thesis empirically explores the recognition and challenges which are solely related to the Pashto language, both regarding character-set and the materials which present such complexities. Furthermore, the conceptual and practical background of this thesis regarding complexities of Pashto language is very beneficial regarding OCR for other cursive languages.
A popular model for the locations of fibres or grains in composite materials
is the inhomogeneous Poisson process in dimension 3. Its local intensity function
may be estimated non-parametrically by local smoothing, e.g. by kernel
estimates. They crucially depend on the choice of bandwidths as tuning parameters
controlling the smoothness of the resulting function estimate. In this
thesis, we propose a fast algorithm for learning suitable global and local bandwidths
from the data. It is well-known, that intensity estimation is closely
related to probability density estimation. As a by-product of our study, we
show that the difference is asymptotically negligible regarding the choice of
good bandwidths, and, hence, we focus on density estimation.
There are quite a number of data-driven bandwidth selection methods for
kernel density estimates. cross-validation is a popular one and frequently proposed
to estimate the optimal bandwidth. However, if the sample size is very
large, it becomes computational expensive. In material science, in particular,
it is very common to have several thousand up to several million points.
Another type of bandwidth selection is a solve-the-equation plug-in approach
which involves replacing the unknown quantities in the asymptotically optimal
bandwidth formula by their estimates.
In this thesis, we develop such an iterative fast plug-in algorithm for estimating
the optimal global and local bandwidth for density and intensity estimation with a focus on 2- and 3-dimensional data. It is based on a detailed
asymptotics of the estimators of the intensity function and of its second
derivatives and integrals of second derivatives which appear in the formulae
for asymptotically optimal bandwidths. These asymptotics are utilised to determine
the exact number of iteration steps and some tuning parameters. For
both global and local case, fewer than 10 iterations suffice. Simulation studies
show that the estimated intensity by local bandwidth can better indicate
the variation of local intensity than that by global bandwidth. Finally, the
algorithm is applied to two real data sets from test bodies of fibre-reinforced
high-performance concrete, clearly showing some inhomogeneity of the fibre
intensity.
Eine Anpassung von Wasserversorgungs- und Abwasserentsorgungssystemen im ländlichen Raum kann aufgrund vielfältiger Herausforderungen wie demografischen, siedlungsstrukturellen und klimatischen Veränderungen erforderlich werden. Im Zuge dessen können auch die Nachhaltigkeit und Ressourceneffizienz der bestehenden Systeme gesteigert werden. Das Ziel dieser Arbeit ist die Ableitung von Handlungsempfehlungen zur Unterstützung der notwendigen Anpassungsprozesse der Abwasserentsorgung ländlicher Gemeinden. Dazu werden verschiedene Transformationspfade für Abwassersysteme aufgezeigt und analysiert.
In dieser Arbeit wird ein softwaregestütztes Entscheidungs- und Optimierungssystem angewendet und evaluiert, dass optimale Anpassungsmöglichkeiten aufgezeigt. Das gemischt-ganzzahlige lineare Optimierungsmodell berechnet für jede Gemeinde in Abhängigkeit von dem ausgewählten Szenario und vorgegebenen Zielen den optimalen Transformationspfad mit seiner zeitlichen und räumlichen Umsetzung. In den Szenarien werden zukünftige Entwicklungen der Bevölkerung, der Siedlungsstruktur, des Wasserbedarfs, der Kosten technischer Anlagen und des Klimawandels berücksichtigt. Die Zielfunktion bildet sich aus der gewichteten Summe ökonomischer, ökologischer und sozialer Bewertungskriterien. Die beispielhafte Anwendung des Modells erfolgt für zwei repräsentative ländliche Modellkommunen in Rheinland-Pfalz.
Durch eine detaillierte Auswertung und Evaluierung von ausgewählten Kombinationen von Szenarien und Bewertungskriterien kann das Spektrum an möglichen Transformationspfaden von der Erhaltung des zentralen Systems bis hin zu dezentralen und ressourcenorientierten Systemen aufgezeigt werden. Sensitivitätsbetrachtungen zeigen, dass die Auswahl und Gewichtung der Bewertungskriterien und die lokalen Randbedingungen der Gemeinde einen größeren Einfluss auf die resultierende Transformationspfade haben als die Auswahl der Szenarien.
Der Zustand des Entwässerungssystems wie der Anteil alter Kanäle, ein großer Anteil Mischsystem, große Durchmesser und eine große Kanallänge pro Einwohner sowie eine niedrige Siedlungsdichte fördern dezentrale Strukturen und sind geeignete Voraussetzungen für einen Systemwechsel. Bei der Priorisierung der Ziele Flexibilität, Wasserbilanz und Wasserrecycling wird die Dezentralisierung eines Systems mit Kleinkläranlagen favorisiert. Ein ressourcenorientiertes System mit einer Grau- und Schwarzwassertrennung ist nur zukünftig vorteilhaft, wenn die Ziele Wasserrecycling, Nährstoffrecycling und/oder Energieeffizienz priorisiert werden. Wenn ein Systemwechsel vollzogen werden soll, müssen auch die Auswirkungen auf die Wasserversorgung und Abwasserreinigung untersucht werden.
Es kann gezeigt werden, dass bei einer abnehmenden Bevölkerung dezentrale und ressourcenorientierte Systeme im ländlichen Raum eine Alternative darstellen. Zur Begleitung von Transformationsprozessen ist die Verwendung einer adäquaten Methodik zum Aufzeigen von verschiedenen Systemalternativen (z.B. mathematische Optimierung) zielführend.
Analyzing Centrality Indices in Complex Networks: an Approach Using Fuzzy Aggregation Operators
(2018)
The identification of entities that play an important role in a system is one of the fundamental analyses being performed in network studies. This topic is mainly related to centrality indices, which quantify node centrality with respect to several properties in the represented network. The nodes identified in such an analysis are called central nodes. Although centrality indices are very useful for these analyses, there exist several challenges regarding which one fits best
for a network. In addition, if the usage of only one index for determining central
nodes leads to under- or overestimation of the importance of nodes and is
insufficient for finding important nodes, then the question is how multiple indices
can be used in conjunction in such an evaluation. Thus, in this thesis an approach is proposed that includes multiple indices of nodes, each indicating
an aspect of importance, in the respective evaluation and where all the aspects of a node’s centrality are analyzed in an explorative manner. To achieve this
aim, the proposed idea uses fuzzy operators, including a parameter for generating different types of aggregations over multiple indices. In addition, several preprocessing methods for normalization of those values are proposed and discussed. We investigate whether the choice of different decisions regarding the
aggregation of the values changes the ranking of the nodes or not. It is revealed that (1) there are nodes that remain stable among the top-ranking nodes, which
makes them the most central nodes, and there are nodes that remain stable
among the bottom-ranking nodes, which makes them the least central nodes; and (2) there are nodes that show high sensitivity to the choice of normalization
methods and/or aggregations. We explain both cases and the reasons why the nodes’ rankings are stable or sensitive to the corresponding choices in various networks, such as social networks, communication networks, and air transportation networks.
Kapitel eins fokussiert auf die Forschungsfragen und Bezugstheorien der vorliegenden Arbeit. In Kapitel zwei geht es um die Darstellung des Anerkennungsbegriffs, Überlegungen zur Entwicklung von Anerkennungsverhältnissen und die drei für diese Arbeit wesentlichen Anerkennungstheorien von Wolfgang Müller-Commichau, Axel Honneth und Werner Nothdurft. Kapitel drei ist der 'Emotionalen Kompetenz' gewidmet und umfasst neben Definitionsversuchen die Beschreibung unterschiedlicher Aspekte emotionaler Kompetenz, die Darstellung der Begriffe Empathie, Verstehensfähigkeit, Introspektions- und Selbstreflexionsfähigkeit – Eigenschaften, die sowohl für die Suche als auch für das Geben von Anerkennung Bedeutung haben und schließt mit Überlegungen zur Förderung emotionaler Kompetenz in Kontexten der Erwachsenenbildung. In Kapitel vier gerät die Kommunikationsfähigkeit/Gesprächskompetenz in den Fokus. Nach einer Beschreibung der Begriffe werden Fragen dazu, wie gelingende Gespräche, wie ein verstehender Dialog aussehen könnte, thematisiert und wie Kommunikationsfähigkeit/ Gesprächskompetenz in erwachsenenpädagogischen Settings weiterentwickelt werden könnte. Kapitel fünf stellt anerkennende pädagogische Beziehungsgestaltungen ins Zentrum der Betrachtung. In den Fokus gelangen wechselseitige Anerkennungsverhältnisse (Beispiel Anerkennungsskulptur) und die bejahende/ ermöglichende bzw. begrenzende Perspektive (Verkennung, Missverstehen, ausbleibende Anerkennung) von Anerkennung. Kapitel sechs bringt eine Zusammenfassung der Ergebnisse, die in ihrer Relevanz für die Gestaltung von Anerkennungsverhältnissen in Kontexten der Erwachsenenbildung dargestellt werden. Am Ende des Kapitels geht es um Überlegungen zu einer Kultur der Anerkennung, um Anerkennung als Haltung. Das Schlusskapitel sieben bringt ein Resümee und einen Ausblick mit neuen Forschungsfragen zum Thema Anerkennung.
Biological soil crusts (biocrusts) are a common element of the Queensland (Australia) dry savannah ecosystem and are composed of cyanobacteria, algae, lichens, bryophytes, fungi and heterotrophic bacteria. Here we report how the CO2 gas exchange of the cyanobacteria-dominated biocrust type from Boodjamulla National Park in the north Queensland Gulf Savannah responds to the pronounced climatic seasonality and on their quality as a carbon sink using a semi-automatic cuvette system. The dominant cyanobacteria are the filamentous species Symplocastrum purpurascens together with Scytonema sp. Metabolic activity was recorded between 1 July 2010 and 30 June 2011, during which CO2 exchange was only evident from November 2010 until mid-April 2011, representative of 23.6 % of the 1-year recording period. In November at the onset of the wet season, the first month (November) and the last month (April) of activity had pronounced respiratory loss of CO2. The metabolic active period accounted for 25 % of the wet season and of that period 48.6 % was net photosynthesis (NP) and 51.4 % dark respiration (DR). During the time of NP, net photosynthetic uptake of CO2 during daylight hours was reduced by 32.6 % due to water supersaturation. In total, the biocrust fixed 229.09 mmol CO2 m−2 yr−1, corresponding to an annual carbon gain of 2.75 g m−2 yr−1. Due to malfunction of the automatic cuvette system, data from September and October 2010 together with some days in November and December 2010 could not be analysed for NP and DR. Based on climatic and gas exchange data from November 2010, an estimated loss of 88 mmol CO2 m−2 was found for the 2 months, resulting in corrected annual rates of 143.1 mmol CO2 m−2 yr−1, equivalent to a carbon gain of 1.7 g m−2 yr−1. The bulk of the net photosynthetic activity occurred above a relative humidity of 42 %, indicating a suitable climatic combination of temperature, water availability and light intensity well above 200 µmol photons m−2 s−1 photosynthetic active radiation. The Boodjamulla biocrust exhibited high seasonal variability in CO2 gas exchange pattern, clearly divided into metabolically inactive winter months and active summer months. The metabolic active period commences with a period (of up to 3 months) of carbon loss, likely due to reestablishment of the crust structure and restoration of NP prior to about a 4-month period of net carbon gain. In the Gulf Savannah biocrust system, seasonality over the year investigated showed that only a minority of the year is actually suitable for biocrust growth and thus has a small window for potential contribution to soil organic matter.
In this thesis, we focus on the application of the Heath-Platen (HP) estimator in option
pricing. In particular, we extend the approach of the HP estimator for pricing path dependent
options under the Heston model. The theoretical background of the estimator
was first introduced by Heath and Platen [32]. The HP estimator was originally interpreted
as a control variate technique and an application for European vanilla options was
presented in [32]. For European vanilla options, the HP estimator provided a considerable
amount of variance reduction. Thus, applying the technique for path dependent options
under the Heston model is the main contribution of this thesis.
The first part of the thesis deals with the implementation of the HP estimator for pricing
one-sided knockout barrier options. The main difficulty for the implementation of the HP
estimator is located in the determination of the first hitting time of the barrier. To test the
efficiency of the HP estimator we conduct numerical tests with regard to various aspects.
We provide a comparison among the crude Monte Carlo estimation, the crude control
variate technique and the HP estimator for all types of barrier options. Furthermore, we
present the numerical results for at the money, in the money and out of the money barrier
options. As numerical results imply, the HP estimator performs superior among others
for pricing one-sided knockout barrier options under the Heston model.
Another contribution of this thesis is the application of the HP estimator in pricing bond
options under the Cox-Ingersoll-Ross (CIR) model and the Fong-Vasicek (FV) model. As
suggested in the original paper of Heath and Platen [32], the HP estimator has a wide
range of applicability for derivative pricing. Therefore, transferring the structure of the
HP estimator for pricing bond options is a promising contribution. As the approximating
Vasicek process does not seem to be as good as the deterministic volatility process in the
Heston setting, the performance of the HP estimator in the CIR model is only relatively
good. However, for the FV model the variance reduction provided by the HP estimator is
again considerable.
Finally, the numerical result concerning the weak convergence rate of the HP estimator
for pricing European vanilla options in the Heston model is presented. As supported by
numerical analysis, the HP estimator has weak convergence of order almost 1.
The design of the fifth generation (5G) cellular network should take account of the emerging services with divergent quality of service requirements. For instance, a vehicle-to-everything (V2X) communication is required to facilitate the local data exchange and therefore improve the automation level in automated driving applications. In this work, we inspect the performance of two different air interfaces (i.e., LTE-Uu and PC5) which are proposed by the third generation partnership project (3GPP) to enable the V2X communication. With these two air interfaces, the V2X communication can be realized by transmitting data packets either over the network infrastructure or directly among traffic participants. In addition, the ultra-high reliability requirement in some V2X communication scenarios can not be fulfilled with any single transmission technology (i.e., either LTE-Uu or PC5). Therefore, we discuss how to efficiently apply multi-radio access technologies (multi-RAT) to improve the communication reliability. In order to exploit the multi-RAT in an efficient manner, both the independent and the coordinated transmission schemes are designed and inspected. Subsequently, the conventional uplink is also extended to the case where a base station can receive data packets through both the LTE-Uu and PC5 interfaces. Moreover, different multicast-broadcast single-frequency network (MBSFN) area mapping approaches are also proposed to improve the communication reliability in the LTE downlink. Last but not least, a system level simulator is implemented in this work. The simulation results do not only provide us insights on the performances of different technologies but also validate the effectiveness of the proposed multi-RAT scheme.
The Symbol Grounding Problem (SGP) is one of the first attempts to proposed a hypothesis about mapping abstract concepts and the real world. For example, the concept "ball" can be represented by an object with a round shape (visual modality) and phonemes /b/ /a/ /l/ (audio modality).
This thesis is inspired by the association learning presented in infant development.
Newborns can associate visual and audio modalities of the same concept that are presented at the same time for vocabulary acquisition task.
The goal of this thesis is to develop a novel framework that combines the constraints of the Symbol Grounding Problem and Neural Networks in a simplified scenario of association learning in infants. The first motivation is that the network output can be considered as numerical symbolic features because the attributes of input samples are already embedded. The second motivation is the association between two samples is predefined before training via the same vectorial representation. This thesis proposes to associate two samples and the vectorial representation during training. Two scenarios are considered: sample pair association and sequence pair association.
Three main contributions are presented in this work.
The first contribution is a novel Symbolic Association Model based on two parallel MLPs.
The association task is defined by learning that two instances that represent one concept.
Moreover, a novel training algorithm is defined by matching the output vectors of the MLPs with a statistical distribution for obtaining the relationship between concepts and vectorial representations.
The second contribution is a novel Symbolic Association Model based on two parallel LSTM networks that are trained on weakly labeled sequences.
The definition of association task is extended to learn that two sequences represent the same series of concepts.
This model uses a training algorithm that is similar to MLP-based approach.
The last contribution is a Classless Association.
The association task is defined by learning based on the relationship of two samples that represents the same unknown concept.
In summary, the contributions of this thesis are to extend Artificial Intelligence and Cognitive Computation research with a new constraint that is cognitive motivated. Moreover, two training algorithms with a new constraint are proposed for two cases: single and sequence associations. Besides, a new training rule with no-labels with promising results is proposed.
To investigate whether participants can activate only one spatially oriented number line at a time or
multiple number lines simultaneously, they were asked to solve a unit magnitude comparison task
(unit smaller/larger than 5) and a parity judgment task (even/odd) on two-digit numbers. In both these
primary tasks, decades were irrelevant. After some of the primary task trials (randomly), participants
were asked to additionally solve a secondary task based on the previously presented number. In
Experiment 1, they had to decide whether the two-digit number presented for the primary task was
larger or smaller than 50. Thus, for the secondary task decades were relevant. In contrast, in Experiment
2, the secondary task was a color judgment task, which means decades were irrelevant. In Experiment
1, decades’ and units’ magnitudes influenced the spatial association of numbers separately. In contrast,
in Experiment 2, only the units were spatially associated with magnitude. It was concluded that
multiple number lines (one for units and one for decades) can be activated if attention is focused on
multiple, separate magnitude attributes.
Berufliche Umbrüche sind Teil der Entwicklung eines Menschen. Sie berühren auch seine Persönlichkeit und seine Identität. Wann kann man von gelingender Identitätsentwicklung sprechen? Woran lässt sich diese festmachen? Kann berufsbiografische Diskontinuität einen gelingenden Beitrag zur Identitätsentwicklung darstellen? Und wenn ja, wie? Was bedeutet es, berufliche Umbrüche nicht nur anzunehmen, sondern auch zu gestalten, damit sie einen positiven Beitrag zur Identitätsentwicklung leisten? Welche Faktoren sind dafür förderlich? Und wie sollten diese Erkenntnisse in der erwachsenenbildnerischen Praxis berücksichtigt werden? Die Arbeit nimmt zunächst den Begriff der Identität in den Blick und wendet sich besonders dem Begriff der Anerkennung zu. Nach Betrachtungen zum Zusammenhang von Identität und Erwerbsarbeit sowie einem Überblick über die Phasen von Erwerbsbiografien werden erwachsenenpädagogische Überlegungen angestellt, die für Transitionsprozesse benötigte Kompetenzen ins Zentrum stellen und Konsequenzen für die Arbeit in Einrichtungen der Erwachsenenbildung darstellen.
Fucoidan is a class of biopolymers mainly found in brown seaweeds. Due to its diverse medical importance, homogenous supply as well as a GMP-compliant product is of a special interest. Therefore, in addition to optimization of its extraction and purification from classical resources, other techniques were tried (e.g., marine tissue culture and heterologous expression of enzymes involved in its biosynthesis). Results showed that 17.5% (w/w) crude fucoidan after pre-treatment and extraction was obtained from the brown macroalgae F. vesiculosus. Purification by affinity chromatography improved purity relative to the commercial purified product. Furthermore, biological investigations revealed improved anti-coagulant and anti-viral activities compared with crude fucoidan. Furthermore, callus-like and protoplast cultures as well as bioreactor cultivation were developed from F. vesiculosus representing a new horizon to produce fucoidan biotechnologically. Moreover, heterologous expression of several enzymes involved in its biosynthesis by E. coli (e.g., FucTs and STs) demonstrated the possibility to obtain active enzymes that could be utilized in enzymatic in vitro synthesis of fucoidan. All these competitive techniques could provide the global demands from fucoidan.
Areal optical surface topography measurement is an emerging technology for industrial quality control. However, neither calibration procedures nor the utilization of material measures are standardized. State of the art is the calibration of a set of metrological characteristics with multiple calibration samples (material measures). Here, we propose a new calibration sample (artefact) capable of providing the entire set of relevant metrological characteristics within only one single sample. Our calibration artefact features multiple material measures and is manufactured with two-photon laser lithography (direct laser writing, DLW). This enables a holistic calibration of areal topography measuring instruments with only one series of measurements and without changing the sample.
Grape powdery mildew, Erysiphe necator, is one of the most significant plant pathogens, which affects grape growing regions world-wide. Because of its short generation time and the production of large amounts of conidia throughout the season, E. necator is classified as a moderate to high risk pathogen with respect to the development of fungicide resistance. The number of fungicidal mode of actions available to control powdery mildew is limited and for some of them resistances are already known. Aryl-phenyl-ketones (APKs), represented by metrafenone and pyriofenone, and succinate-dehydrogenase inhibitors (SDHIs), composed of numerous active ingredients, are two important fungicide classes used for the control of E. necator. Over the period 2014 to 2016, the emergence and development of metrafenone and SDHI resistant E. necator isolates in Europe was followed and evaluated. The distribution of resistant isolates was thereby strongly dependent on the European region. Whereas the north-western part is still predominantly sensitive, samples from east European countries showed higher resistance frequencies.
Classical sensitivity tests with obligate biotrophs can be challenging regarding sampling, transport and especially the maintenance of the living strains. Whenever possible, molecular genetic methods are preferred for a more efficient monitoring. Such methods require the knowledge of the resistance mechanisms. The exact molecular target and the resistance mechanism of metrafenone is still unknown. Whole genome sequencing of metrafenone sensitive and resistant wheat powdery mildew isolates, as well as adapted laboratory mutants of Aspergillus nidulans, where performed with the aim to identify proteins potentially linked to the mode of action or which contribute to metrafenone resistance. Based on comparative SNP analysis, four proteins potentially associated with metrafenone resistance were identified, but validation studies could not confirm their role in metrafenone resistance. In contrast to APKs, the mode of action of SDHIs is well understood. Sequencing of the sdh-genes of less sensitive E. necator isolates identified four different target-site mutations, the B-H242R, B-I244V, C-G169D and C-G169S, in sdhB and sdhC, respectively. Based on this information it was possible to develop molecular genetic monitoring methods for the mutations B-H242R and C-G169D. In 2016, the B-H242R was thereby identified as by far the most frequent mutation. Depending on the analysed SDH compound and the sdh-genotype, different sensitivities were observed and revealed a complex cross-resistance pattern.
Growth competition assays without selection pressure, with mixtures of sensitive and resistant E. necator isolates, were performed to determine potential fitness costs associated with fungicide resistance. With the experimental setups used, a clear fitness disadvantage associated with metrafenone resistance was not identified, although a strong variability of fitness was observed among the tested resistant E. necator isolates. For isolates with a reduced sensitivity towards SDHIs, associated fitness costs were dependent on the sdh-genotype analysed. Competition tests with the B-H242R genotypes gave evidence that there are no fitness costs associated with this mutation. In contrast, the C-G169D genotypes were less competitive, indicating a restricted fitness compared to the tested sensitive partners. Competition assays of field isolates, which exhibited several resistances towards different fungicide classes, indicated that there are no fitness costs associated with a multiple resistant phenotype in E. necator. Overall, these results clearly indicate the importance to analyse a representative number of isolates with sensitive and resistant phenotypes.
Using valuation theory we associate to a one-dimensional equidimensional semilocal Cohen-Macaulay ring \(R\) its semigroup of values, and to a fractional ideal of \(R\) we associate its value semigroup ideal. For a class of curve singularities (here called admissible rings) including algebroid curves the semigroups of values, respectively the value semigroup ideals, satisfy combinatorial properties defining good semigroups, respectively good semigroup ideals. Notably, the class of good semigroups strictly contains the class of value semigroups of admissible rings. On good semigroups we establish combinatorial versions of algebraic concepts on admissible rings which are compatible with their prototypes under taking values. Primarily we examine duality and quasihomogeneity.
We give a definition for canonical semigroup ideals of good semigroups which characterizes canonical fractional ideals of an admissible ring in terms of their value semigroup ideals. Moreover, a canonical semigroup ideal induces a duality on the set of good semigroup ideals of a good semigroup. This duality is compatible with the Cohen-Macaulay duality on fractional ideals under taking values.
The properties of the semigroup of values of a quasihomogeneous curve singularity lead to a notion of quasihomogeneity on good semigroups which is compatible with its algebraic prototype. We give a combinatorial criterion which allows to construct from a quasihomogeneous semigroup \(S\) a quasihomogeneous curve singularity having \(S\) as semigroup of values.
As an application we use the semigroup of values to compute endomorphism rings of maximal ideals of algebroid curves. This yields an explicit description of the intermediate rings in an algorithmic normalization of plane central arrangements of smooth curves based on a criterion by Grauert and Remmert. Applying this result to hyperplane arrangements we determine the number of steps needed to compute the normalization of a the arrangement in terms of its Möbius function.
Congress Report 2017.11-12
(2018)
Congress Report 2018.1-4
(2018)
Congress Report 2018.5-8
(2018)
Congress Report 2018.9-10
(2018)
This thesis consists of five chapters. Chapter one elaborates on the principle of cognitive consistency and provides an overview of what extant research refers to as cognitive consistency theories (e.g., Abelson et al., 1968; Harmon-Jones & Harmon-Jones, 2007; Simon, Stenstrom, & Read, 2015). Moreover, it describes the most prominent theoretical representatives in this context, namely balance theory (Heider, 1946, 1958), congruity theory (Osgood & Tannenbaum, 1955), and cognitive dissonance theory (Festinger, 1957). Chapter one further outlines the role of individuals’ preference for cognitive consistency in the context of financial resource acquisition, the recruitment of employees and the acquisition of customers in the entrepreneurial context.
Chapter two is co-authored by Prof. Dr. Matthias Baum and presents two separate studies in which we empirically investigate the hypothesis that social entrepreneurs face a systematic disadvantage, compared to for-profit entrepreneurs, when seeking to acquire financial resources. Further, our work goes beyond existing research by introducing biased perceptions as a factor that may constrain social enterprise resource acquisition and therefore possibly stall the process of social value creation. On the foundation of role congruity theory (Eagly & Karau, 2002), we emphasize on the question whether social entrepreneurs provide signals which are less congruent with the stereotype of successful entrepreneurs and, in such, are perceived as less competent. We further test whether such biased competency perceptions feed forward into a lower probability to receive funding.
Chapter three is also co-authored by Prof. Dr. Matthias Baum as well as by Eva Henrich. The aim of this chapter is to further our understanding of the early recruitment phase and to contribute to the current debate about how firms should orchestrate their recruitment channels in order to enhance the creation of employer knowledge. We introduce the concept of integrated marketing communication into the recruitment field and examine how the level of consistency regarding job or organization information affects the recall and the recognition of that information. We additionally test whether information consistency among multiple recruitment channels influences information recognition failure quota. Answering this question is important as by failing to remember the source of recruitment information, job seekers may attribute job information to the wrong firm and thus create an incorrect employer knowledge.
Chapter four, which is co-authored by Prof. Dr. Matthias Baum, introduces customer congruity perceptions between a brand and a reward in the context of customer referral programs as an essential driver of the effectiveness of such programs. More precisely, we posit and empirically test a model according to which the decision-making process of the customer recommending a firm involves multiple mental steps and assumes reward perceptions to be an immediate antecedent of brand evaluation, which then, ultimately shapes the likelihood of recommendation. The level of congruity/incongruity is set up as an antecedent state and affects the perceived attractiveness of the reward. Our work contributes to the discussion on the optimal level of congruity between a prevailing schema in the mind of the customer and a stimulus presented. In addition, chapter four introduces customer referral programs as a strategic tool for brand managers. Chapter four is further published in Psychology & Marketing.
Chapter five first proposes that marketing strategies specifically designed to induce word-of-mouth (WOM) behavior are particular relevant for new ventures. Against the background that previous research suggests that customer perceptions of young firm age may influence customer behavior and the degree to which customers support new ventures (e.g., Choi & Shepherd, 2005; Stinchcombe, 1965), we secondly conduct an experiment to examine the causal mechanisms linking firm age and customer WOM. Chapter five, too, is co-authored by Prof. Dr. Matthias Baum.
Das 2,2′-Bipyrimidinradikalanion als Brückenligand für Komplexe mit L-N\(_\text{4}\)Me\(_\text{2}\)
(2018)
Im Rahmen dieser Dissertationsschrift gelang es erstmals 3d-Metallionen über ein 2,2′-Bipyrimidinradikalanion zu verbrücken und zu isolieren. Der für sich betrachtet instabile Radikalbrückenligand wurde hierbei in situ durch Reduktion mit Cobaltocen generiert und durch Koordination stabilisiert. Es konnte neben verschiedenen Referenzverbindungen eine Reihe von vier unter Luftausschluss stabilen homodimetallischen Verbindungen mit dem [{M\(^\text{II}\)(L-N\(_\text{4}\)Me\(_\text{2}\))}\(_\text{2}\)(μ-bpym\(^\text{●}\))]\(^\text{3+}\)-Komplexkation (mit M = Zn (\(\textbf{2}\)), Ni (\(\textbf{6}\)), Co (\(\textbf{8}\)) und Fe (\(\textbf{12}\)) synthetisiert, vollständig charakterisiert und miteinander verglichen werden. Durch Gegenüberstellung der strukturellen Parameter des verbrückend koordinierten 2,2′-Bipyrimidinradikalanions in den zweikernigen Verbindungen wurden für dieses charakteristische Bindungslängenbereiche festgestellt. Weiterhin wurden IR- und UV/Vis-spektroskopisch typische Banden des verbrückend koordinierten 2,2′-Bipyrimidinradikalanions gefunden. Durch cyclovoltammetrische und NMR-spektroskopische Untersuchungen wurde der Reaktionspfad zu den dinuklearen Verbindungen aufgeklärt. An \(\textbf{2}\) wurden die intrinsischen ESR-spektroskopischen Eigenschaften der 2,2′-Bipyrimidinradikalanion-Brücke untersucht. Die Elektronendichte des Radikals in \(\textbf{2}\) ist hauptsächlich auf dem Brückenliganden verortet und es liegt ein S = 1/2 System vor. SQUID-magnetometrische Messungen an \(\textbf{6}\) zeigen eine starke ferromagnetische Kopplung zwischen den Nickelionen und der Radikalbrücke, welche zu einem S = 5/2 Spingrundzustand führt. Der S = 5/2 Zustand wurde mittels X-Band-ESR-Spektroskopie bestätigt. Durch Hochfeld-ESR-Spektroskopie wurde ebenfalls die ferromagnetische Kopplung bestätigt und die Nullfeldaufspaltung der Nickelionen in \(\textbf{6}\) eindeutig als schwach negativ bestimmt. Röntgenkristallographische Untersuchungen an \(\textbf{8}\) zeigen bei D\(_\text{2h}\)-Symmetrie einen über einen weiten Temperaturbereich stabilen low-spin/high-spin Zustand der beiden Cobaltionen. Dies alleine ist für Cobaltionen nach bisherigem Kenntnisstand einzigartig. \(\textbf{8}\) ist zudem die erste Verbindung, in welcher diese Begebenheiten mit einem direkt an die Metallzentren koordinierten Radikalbrückenliganden kombiniert vorliegen. Der low-spin/high-spin Zustand wurde weiterhin durch EXAFS- und XANES-Messungen verifiziert. Mit der Verbindung [{Co(L-N\(_\text{4}\)Me\(_\text{2}\))}\(_\text{2}\)(μ-Ph\(_\text{2}\)bpym\(^\text{●}\))](ClO\(_\text{4}\))\(_\text{3}\) (\(\textbf{10}\)) wurde eine weitere radikalverbrückte Verbindung synthetisiert, in der beide Cobaltionen bei identischer Koordinationsumgebung über einen weiten Temperaturbereich in unterschiedlichem Spinzustand vorliegen. SQUID-magnetometrische Untersuchungen an \(\textbf{8}\) und \(\textbf{10}\) zeigen, dass in beiden Verbindungen die low-spin Cobaltionen moderat ferro-, die high-spin Cobaltionen stark antiferromagnetisch mit der jeweiligen Radikalbrücke koppeln, was in beiden Fällen zu einem S = 3/2 Grundzustand führt. Der S = 3/2 Grundzustand wurde ebenfalls durch X-Band-ESR-Spektroskopie bestätigt. In \(\textbf{8}\) und \(\textbf{10}\) konnte jeweils ein Spincrossover des low-spin Cobaltions zum high-spin Zustand festgestellt werden. Dieser wurde mittels XRD-Analytik und SQUID-Magnetometrie für beide Verbindungen und für \(\textbf{8}\) zusätzlich durch EXAFS-Messungen, XANES-Messungen und temperaturabhängige IR-Spektroskopie nachgewiesen. Die Spincrossovereigenschaften sind zusammen mit den anderen vorgenannten Eigenschaften dieser neuen zweikernigen Cobaltverbindungsklasse ein weiteres Alleinstellungsmerkmal. Die einkernigen Referenzverbindungen [Co(L-N\(_\text{4}\)Me\(_\text{2}\))(bpym)](ClO\(_\text{4}\))\(_\text{2}\) (\(\textbf{9a}\)) und [Co(L-N\(_\text{4}\)Me\(_\text{2}\))(Ph\(_\text{2}\)bpym)](ClO\(_\text{4}\))\(_\text{2}\) ∙ MeCN (\(\textbf{11}\)) zeigen jeweils ebenfalls Spincrossovereigenschaften, was mittels SQUID-Magnetometrie und im Fall von \(\textbf{11}\) zusätzlich durch XRD-Analytik und temperaturabhängige IR-Spektroskopie nachgewiesen wurde. In \(\textbf{12}\) liegen beide Eisenionen im low-spin Zustand vor. Dies wurde röntgenkristallographisch und mittels Mößbauer-Spektroskopie bestätigt. X-Band-ESR-spektroskopisch wird ein Signal einer S = 1/2 Spezies gefunden, welches durch das brückenligandzentrierte Radikal hervorgerufen wird.
Betrachtet man sowohl die klassische betriebs-wirtschaftliche Literatur als auch die Literatur der Controlling-Forschung, so ist ersichtlich, dass jeweils eine Anspruchskongruenz der Eigenkapitalgeber unterstellt wird, welche zu einem einheitlichen Diskontsatz führt, wie dies insbesondere auch im Shareholder Value-Ansatz deutlich wird. Grundlage dieses Postulates ist die neoklassische Theorie, welche unter restriktiven Prämissen die Einmütigkeit der Shareholder hinsichtlich des Formalziels „Shareholder Value“-Maximierung modelltheoretisch abzuleiten vermag. Hierbei werden jedoch ein vollkommener Kapitalmarkt sowie eine Entscheidungssituation unter Sicherheit vorausgesetzt. Beide Prämissen sind auf realen Märkten nicht gegeben. Trotz dieser fehlenden modelltheoretisch strengen Einmütigkeit können jedoch Unternehmen, wie auch empirisch zu sehen ist, offensichtlich durchaus (in gewissen Grenzen) divergierende Shareholderansprüche inkorporieren, welches mit den traditionellen Modellen nicht plausibel abzubilden ist.
Die Frage, wie dies dennoch konzeptionell begründet werden könnte, konstituiert die Ausgangsgrundlage dieses Forschungsbeitrags. Hierbei werden zuerst die standardökonomischen Ansätze zur Klärung der Einmütigkeitsfrage kritisch reflektiert, bevor mit dem Konzept der bounded rationality nach Simon und Gigerenzer eine verhaltenswissenschaftliche Gegenposition eingenommen wird. Diese kann, wie gezeigt wird, als konzeptionelle Grundlage dienen, um die empirisch evidente, hinreichende Einmütigkeit unter den Eigenkapitalgebern eines Unternehmens zu erklären. Hierbei stellt sich jedoch für das Management die zentrale Frage, wie hoch die erwarteten Renditeansprüche der Shareholder legitimer Weise ausfallen dürfen. Diese Frage gewinnt an zusätzlicher Relevanz, wenn man davon ausgeht, dass die Eigenkapitalrenditen im Bezug zum zusätzlichen Risiko, welches die Eigenkapitalgeber tragen, überproportional hoch ausfallen. Das Controlling kann in diesem Kontext einen bedeutenden Beitrag zur Führungsunterstützung des Managements – und damit zu einem dauerhaften Erfolg des Unternehmens – leisten.
Education is the Achilles heel of successful resuscitation in cardiac arrest. Therefore, we aim to contribute to the educational efficiency by providing a novel augmented-reality (AR) guided interactive cardiopulmonary resuscitation (CPR) "trainer". For this trainer, a mixed reality smart glass, Microsoft HoloLens, and a CPR manikin covered with pressure sensors were used. To introduce the CPR procedure to a learner, an application with an intractable virtual teacher model was designed. The teaching scenario consists of the two main parts, theory and practice. In the theoretical part, the virtual teacher provides all information about the CPR procedure. Afterward, the user will be asked to perform the CPR cycles in three different stages. In the first two stages, it is aimed to gain the muscle memory with audio and optical feedback system. In the end, the performance of the participant is evaluated by the virtual teacher.
Das „Herzstück der Gewährleistung“ in Unternehmenskaufverträgen bilden die Jahresabschlussgarantien, sog. Bilanzgarantien. Dabei sichert der Verkäufer dem Käufer auf der Tatbestandseite von Bilanzgarantien zu, dass der Jahresabschluss des Zielunternehmens in Übereinstimmung mit den gesetzlichen Vorschriften er-stellt wurde. Das Interesse des Verkäufers besteht darin, nach dem Verkauf des Unternehmens frei über den Kaufpreis verfügen zu können, ohne dass es zu einer Haftungsinanspruchnahme durch den Käufer kommt. Die Arbeit beschäftigt sich aus unternehmenspraktischer und juristischer Sicht mit den Rechtsfolgen bei Ein-tritt des Garantiefalls, insbesondere der Bilanzauffüllung im Lichte des Schadens-rechts der §§ 249 ff. BGB.
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.
Der vorliegende Bericht beschreibt die Entwicklung und die Inhalte des Hochschulzertifikats „Beraten, Informieren und Schulen in der Pflege" im Kontext des Projekts EB – Pflege und Gesundheit.
Zunächst wird das Vorgehen im Rahmen der Angebotsentwicklung beschrieben. Die Beschreibungen der Kompetenzen, Überlegungen zum Tätigkeitsfeld und die Verknüpfung der Ergebnisse der Bedarfserhebungen mit den konkreten Inhalten des Zertifikats bilden den Schwerpunkt des Berichts. Abschließend werden didaktische Überlegungen zur Gestaltung des Zertifikats und zur Prüfungsform transparent gemacht.
Der vorliegende Bericht beschreibt die Entwicklung von Hochschulzertifikaten des Projekts E-hoch-B – Pflege und Gesundheit und ordnet diese in den Projektzusammenhang ein. Die Methodik der Angebotsentwicklung wird zunächst generell und darauf aufbauend spezifisch für das Zertifikat Ethik und Recht in gemeindenaher Gesundheitsversorgung beschrieben.
Die Beschreibungen der Kompetenzen, Überlegungen zum Tätigkeitsfeld und die Verknüpfung der Ergebnisse der Bedarfserhebungen mit den konkreten Inhalten des Zertifikats bilden den Schwerpunkt des Berichts. Abschließend werden didaktische Überlegungen zur Gestaltung des Zertifikats und zur Prüfungsform transparent gemacht.
Der Zertifikatskurs „Interprofessionelle Kommunikation in gemeindenaher Gesundheitsversorgung“
(2018)
Der vorliegende Bericht beschreibt die Entwicklung und Inhalte des Hochschulzertifikats In-terprofessionelle Kommunikation in gemeindenaher Gesundheitsversorgung im Kontext des Projekts E-hoch-B – Pflege und Gesundheit.
Zunächst wird das Vorgehen im Rahmen der Angebotsentwicklung beschrieben. Die Darstellung der Kompetenzen, Überlegungen zum Tätigkeitsfeld und die Verknüpfung der Ergebnisse der Bedarfserhebungen mit den konkreten Inhalten des Zertifikats bilden den Schwerpunkt des Berichts. Abschließend werden didaktische Überlegungen zur Gestaltung des Zertifikats und zur Prüfungsform transparent gemacht.
Der vorliegende Bericht beschreibt die Entwicklung und Inhalte des Hochschulzertifikats Versorgungsstrategien und psychosoziale Unterstützung für ein Leben mit Demenz zu Hause im Kontext des Projekts E-hoch-B – Pflege und Gesundheit.
Zunächst wird das Vorgehen im Rahmen der Angebotsentwicklung beschrieben. Die Darstellung der Kompetenzen, Überlegungen zum Tätigkeitsfeld und die Verknüpfung der Ergebnisse der Bedarfserhebungen mit den konkreten Inhalten des Zertifikats bilden den Schwerpunkt des Berichts. Abschließend werden didaktische Überlegungen zur Gestaltung des Zertifikats und zur Prüfungsform transparent gemacht.
Fast Internet content delivery relies on two layers of caches on the request path. Firstly, content delivery networks (CDNs) seek to answer user requests before they traverse slow Internet paths. Secondly, aggregation caches in data centers seek to answer user requests before they traverse slow backend systems. The key challenge in managing these caches is the high variability of object sizes, request patterns, and retrieval latencies. Unfortunately, most existing literature focuses on caching with low (or no) variability in object sizes and ignores the intricacies of data center subsystems.
This thesis seeks to fill this gap with three contributions. First, we design a new caching system, called AdaptSize, that is robust under high object size variability. Second, we derive a method (called Flow-Offline Optimum or FOO) to predict the optimal cache hit ratio under variable object sizes. Third, we design a new caching system, called RobinHood, that exploits variances in retrieval latencies to deliver faster responses to user requests in data centers.
The techniques proposed in this thesis significantly improve the performance of CDN and data center caches. On two production traces from one of the world's largest CDN AdaptSize achieves 30-91% higher hit ratios than widely-used production systems, and 33-46% higher hit ratios than state-of-the-art research systems. Further, AdaptSize reduces the latency by more than 30% at the median, 90-percentile and 99-percentile.
We evaluate the accuracy of our FOO analysis technique on eight different production traces spanning four major Internet companies.
We find that FOO's error is at most 0.3%. Further, FOO reveals that the gap between online policies and OPT is much larger than previously thought: 27% on average, and up to 43% on web application traces.
We evaluate RobinHood with production traces from a major Internet company on a 50-server cluster. We find that RobinHood improves the 99-percentile latency by more than 50% over existing caching systems.
As load imbalances grow, RobinHood's latency improvement can be more than 2x. Further, we show that RobinHood is robust against server failures and adapts to automatic scaling of backend systems.
The results of this thesis demonstrate the power of guiding the design of practical caching policies using mathematical performance models and analysis. These models are general enough to find application in other areas of caching design and future challenges in Internet content delivery.
Der Fokus der vorliegenden Arbeit liegt auf endlosfaser- und langfaserverstärkten
thermoplastischen Materialien. Hierfür wurde das „multilayered hybrid
(MLH)“ Konzept entwickelt und auf zwei Halbzeuge, den MLH-Roving und die MLHMat
angewendet. Der MLH-Roving ist ein Roving (bestehend aus Endlosfasern), der
durch thermoplastische Folien in mehrere Schichten geteilt wird. Der MLH-Roving
wird durch eine neuartige Spreizmethode mit anschließender thermischen Fixierung
und abschließender mehrfacher Faltung hergestellt. Dadurch können verschiedene
Faser-Matrix-Konfigurationen realisiert werden. Die MLH-Mat ist ein
glasmattenverstärktes thermoplastisches Material, das für hohe Fasergehalte bis 45
vol. % und verschiedene Matrixpolymere, z.B. Polypropylen (PP) und Polyamide 6
(PA6) geeignet ist. Sie zeichnet sich durch eine hohe Homogenität in der
Flächendichte und in der Faserrichtung aus. Durch dynamische Crashversuche mit
auf MLH-Roving und MLH-Mat basierenden Probekörpern wurden das
Crashverhalten und die Performance untersucht. Die Ergebnisse der Crashkörper
basierend auf langfaserverstärktem Material (MLH-Mat) und endlosfaserverstärktem
Material (MLH-Roving) waren vergleichbar. Die PA6-Typen zeigten eine bessere
Crashperformance als PP-Typen.
The present work deals with continuous fiber- and long fiber reinforced thermoplastic
materials. The concept of multilayered hybrid (MLH) structure was developed and
applied to the so-called MLH-roving and MLH-mat. The MLH-roving is a continuous
fiber roving separated evenly into several sublayers by thermoplastic films, through
the sequential processes of spreading with a newly derived equation, thermal fixing,
and folding. It was aimed to satisfy the variety of material configuration as well as the
variety in intermediate product. The MLH-mat is a glass mat reinforced thermoplastic
(GMT)-like material that is suitable for high fiber contents up to 45 vol. % and various
matrix polymers, e.g. polypropylene (PP), polyamide 6 (PA6). It showed homogeneity
in areal density, random directional fiber distribution, and reheating stability required
for molding process. On the MLH-roving and MLH-mat materials, the crash behavior
and performance were investigated by dynamic crash test. Long fiber reinforced
materials (MLH-mat) were equivalent to continuous fiber reinforced materials (MLHroving),
and PA6 grades showed higher crash performance than PP grades.
Die Medienausstattung von Bildungseinrichtungen ist keine hinreichende, aber eine notwendige Voraussetzung, die Möglichkeiten digitaler Medien für die Unterstützung von Lehr-/Lernprozessen zu nutzen. Damit sind in der Regel hohe Investitionen verbunden, die insbesondere für öffentlich geför- derte Einrichtungen der Erwachsenenbildung nur schwer aufzubringen sind. Um aber neue Zielgruppen anzusprechen und den Sprung in das digitale Zeitalter zu schaffen, ist eine entsprechende Medienausstattung unum- gänglich.
Allerdings liegen bisher kaum Daten dazu vor, wie die Ausstattung der Ein- richtungen der Weiterbildung mit digitalen Medien aussieht. Lediglich ein- zelne Volkshochschulverbände (z.B. Brandenburg) haben in den letzten Mo- naten Befragungen zur Medienausstattung durchgeführt, um auf Grundlage dieser Bestandsaufnahme Maßnahmen zur digitalen Transformation der Volkshochschulen zu unterstützen, wie sie im Strategiepapier der „Erwei- terten Lernwelten“ festgehalten sind.
Vor diesem Hintergrund wurde im Wintersemester 2017/2018 zusammen mit Studierenden des Seminars „Medienpädagogik“ des Studiengangs In- tegrative Sozialwissenschaften der TU Kaiserslautern eine Befragung der Volkshochschulen in Rheinland-Pfalz zur Medienausstattung durchgeführt. Die Ergebnisse dieser Befragung stellen wir in diesem Bericht vor.
Wir möchten uns an dieser Stelle bei den Studierenden, beim Volkshoch- schulverbandes Rheinland-Pfalz und insbesondere auch den Interviewpart- nerinnen und –partnern an den Volkshochschulen in Rheinland-Pfalz für ihre Bereitschaft, Zeit und Auskunft bedanken.
Für individuelle und nachhaltige Mobilität ist Leichtbau unverzichtbar. Die effiziente
Ressourcennutzung ist dafür eine technische Notwendigkeit. Das Gewicht eines
Fahrzeugs beeinflusst die Auslegung von Antriebsleistung, Speicherkapazität und
Strukturintegrität. Kohlenstofffaserverstärkte Kunststoffe ermöglichen über die
Kombination von gewichtsbezogen hoher Festigkeit eine Gewichtsreduktion. Durch
das Resin Transfer Molding Verfahren können entsprechende Komponenten in hoher
Stückzahl hergestellt werden. Zur weiteren Verbreitung des Werkstoffs ist eine
Reduktion der Herstellkosten notwendig. In dieser Arbeit werden zu diesem Zweck
werkzeugseitige Fließkanäle untersucht. Diese verkürzen den Fließweg, den das Fluid
durch die niedrigpermeable Verstärkungsstruktur fließen muss. Zur Charakterisierung
der Auswirkung von Fließkanälen auf den Fließfrontverlauf und die Injektionszeit wird
ein Versuchswerkzeug mit transparenten Werkzeughälften verwendet. Dadurch
können Fließfrontverläufe quantitativ mit einer Auflösung von einem Zeitwert pro 0,14
mm2 miteinander verglichen werden. Eine parabolische Querschnittsform ist
hinsichtlich dem Verhältnis von Ersatzpermeabilität und Querschnittsflächengröße
optimal. Eine kontinuierliche Vergrößerung der Fließkanalquerschnittsgröße wirkt sich
degressiv auf die Injektionszeit aus. Dadurch kann der Zusammenhang zwischen
Fließkanalquerschnittsgröße und Permeabilität der Verstärkungsstruktur quantifiziert
werden. Die Untersuchungen zeigen, dass die Reduktion des Fließwegs mit Hilfe von
Fließkanälen auch die Auswirkung von Falten in der Verstärkungsstruktur auf den
Fließfrontverlauf minimiert. Bei der Untersuchung verschiedener, möglicher
Einflussparameter auf die Fasereinschwemmung in Fließkanäle werden die Fließkanalquerschnittsgröße, Durchströmung und die relative Lagenorientierung
identifiziert. Durch die Verwendung von kleinen, schmalen Fließkanalquerschnitten
(Fließkanalbreite < 1,5 mm) kann eine Ondulation der Fasern vermieden werden.
Durch die kleinen Fließkanalquerschnitte kann die Erhöhung des Bauteilgewichts
minimiert werden. Die Versuchsergebnisse werden in Richtlinien zur Auslegung der
Fließkanalquerschnittsform und –größe zusammengefasst. Abschließend werden die
ermittelten Wirkzusammenhänge anhand eines Beispielbauteils, Stirnwand einer
Karosseriestruktur, validiert.
In this thesis we integrate discrete dividends into the stock model, estimate
future outstanding dividend payments and solve different portfolio optimization
problems. Therefore, we discuss three well-known stock models, including
discrete dividend payments and evolve a model, which also takes early
announcement into account.
In order to estimate the future outstanding dividend payments, we develop a
general estimation framework. First, we investigate a model-free, no-arbitrage
methodology, which is based on the put-call parity for European options. Our
approach integrates all available option market data and simultaneously calculates
the market-implied discount curve. We illustrate our method using stocks
of European blue-chip companies and show within a statistical assessment that
the estimate performs well in practice.
As American options are more common, we additionally develop a methodology,
which is based on market prices of American at-the-money options.
This method relies on a linear combination of no-arbitrage bounds of the dividends,
where the corresponding optimal weight is determined via a historical
least squares estimation using realized dividends. We demonstrate our method
using all Dow Jones Industrial Average constituents and provide a robustness
check with respect to the used discount factor. Furthermore, we backtest our
results against the method using European options and against a so called
simple estimate.
In the last part of the thesis we solve the terminal wealth portfolio optimization
problem for a dividend paying stock. In the case of the logarithmic utility
function, we show that the optimal strategy is not a constant anymore but
connected to the Merton strategy. Additionally, we solve a special optimal
consumption problem, where the investor is only allowed to consume dividends.
We show that this problem can be reduced to the before solved terminal wealth
problem.
Autonomous driving is disrupting the conventional automotive development. In fact, autonomous driving kicks off the consolidation of control units, i.e. the transition from distributed Electronic Control Units (ECUs) to centralized domain controllers. Platforms like Audi’s zFAS demonstrate this very clearly, where GPUs, Custom SoCs, Microcontrollers, and FPGAs are integrated on a single domain controller in order to perform sensor fusion, processing and decision making on a single Printed Circuit Board (PCB). The communication between these heterogeneous components and the algorithms for Advanced Driving Assistant Systems (ADAS) itself requires a huge amount of memory bandwidth, which will bring the Memory Wall from High Performance Computing (HPC) and data-centers directly in our cars. In this paper we highlight the roles and issues of Dynamic Random Access Memories (DRAMs) for future autonomous driving architectures.
Certain brain tumours are very hard to treat with radiotherapy due to their irregular shape caused by the infiltrative nature of the tumour cells. To enhance the estimation of the tumour extent one may use a mathematical model. As the brain structure plays an important role for the cell migration, it has to be included in such a model. This is done via diffusion-MRI data. We set up a multiscale model class accounting among others for integrin-mediated movement of cancer cells in the brain tissue, and the integrin-mediated proliferation. Moreover, we model a novel chemotherapy in combination with standard radiotherapy.
Thereby, we start on the cellular scale in order to describe migration. Then we deduce mean-field equations on the mesoscopic (cell density) scale on which we also incorporate cell proliferation. To reduce the phase space of the mesoscopic equation, we use parabolic scaling and deduce an effective description in the form of a reaction-convection-diffusion equation on the macroscopic spatio-temporal scale. On this scale we perform three dimensional numerical simulations for the tumour cell density, thereby incorporating real diffusion tensor imaging data. To this aim, we present programmes for the data processing taking the raw medical data and processing it to the form to be included in the numerical simulation. Thanks to the reduction of the phase space, the numerical simulations are fast enough to enable application in clinical practice.
Ecophysiological characterizations of photoautotrophic communities are not only necessary to identify the response of carbon fixation related to different climatic factors, but also to evaluate risks connected to changing environments. In biological soil crusts (BSCs), the description of ecophysiological features is difficult, due to the high variability in taxonomic composition and variable methodologies applied. Especially for BSCs in early successional stages, the available datasets are rare or focused on individual constituents, although these crusts may represent the only photoautotrophic component in many heavily disturbed ruderal areas, such as parking lots or building areas with increasing surface area worldwide. We analyzed the response of photosynthesis and respiration to changing BSC water contents (WCs), temperature and light in two early successional BSCs. We investigated whether the response of these parameters was different between intact BSC and the isolated dominating components. BSCs dominated by the cyanobacterium Nostoc commune and dominated by the green alga Zygogonium ericetorum were examined. A major divergence between the two BSCs was their absolute carbon fixation rate on a chlorophyll basis, which was significantly higher for the cyanobacterial crust. Nevertheless, independent of species composition, both crust types and their isolated organisms had convergent features such as high light acclimatization and a minor and very late-occurring depression in carbon uptake at water suprasaturation. This particular setup of ecophysiological features may enable these communities to cope with a high variety of climatic stresses and may therefore be a reason for their success in heavily disturbed areas with ongoing human impact. However, the shape of the response was different for intact BSC compared to separated organisms, especially in absolute net photosynthesis (NP) rates. This emphasizes the importance of measuring intact BSCs under natural conditions for collecting reliable data for meaningful analysis of BSC ecosystem services.
Wird Rotwein im Holzfass gelagert, kommt es meist zu einer Intensivierung und Stabilisierung der Weinfarbe. Ursache ist der durch die Fassdauben diffundierende Sauerstoff, der Ethanol zu Acetaldehyd oxidiert. Dieses bildet Ethylidenbrücken zwischen Anthocyanen und Flavanolen, wodurch intensiv violett gefärbte Pigmente entstehen. Bisher wurden nur die dimeren ethyliden-verbrückten Anthocyan-Flavanol Addukte umfassend erforscht, die jedoch im Wein nicht stabil sind und zu Folgeprodukten reagieren. Deren Struktur ist bisher wenig erforscht. Ein Ziel dieser Arbeit bestand daher darin, die Reaktionsprodukte der ethyliden-verbrückten Anthocyan-Flavanol Dimere im Rotwein zu untersuchen. Dabei wurden erstmals Polyphenoladdukte mit bis zu drei Ethylidenbrücken massenspektrometrisch nachgewiesen. Dies zeigt, dass Weinpigmente durch die Bildung mehrerer Ethylidenbrücken polymerisieren können. Es wurden außerdem mehrere Pigmente gefunden, bei denen ein Anthocyan über zwei Ethylidenbrücken mit anderen Polyphenolen verbunden war. Dies widerlegt die bisherige Annahme, dass sich Anthocyane nur in terminalen Positionen eines polymeren Pigments befinden können. Durch die Quantifizierung ethyliden-verbrückter Di- und Trimere mittels Massenspektrometer wurde deutlich, dass diese Pigmente in höheren Konzentrationen im Rotwein vorliegen als bisher publiziert. Es zeigte sich außerdem, dass bis zu 50 % der durch den Sauerstoff bewirkten Abnahme von Anthocyanen und Flavanolen auf die Bildung ethyliden-verbrückter Di- und Trimere, sowie Vitisin B zurückführen lassen.
Heute werden in der Weinbereitung häufig Edelstahltanks eingesetzt, bei denen es, anders als in Holzfässern, kaum zu Sauerstoffeinträgen kommt. Eine Farbstabilisierung kann somit nicht stattfinden. Dem Rotwein können stattdessen durch das Verfahren der Mikrooxygenierung geringe Mengen Sauerstoff kontrolliert zugesetzt werden. Bei manchen Weinen führt dies jedoch zu einer verringerten Farbintensität statt zu einer Farbvertiefung. Anhand der insgesamt 21 im Rahmen dieser Arbeit untersuchten Weine zeigte sich, dass Sauerstoff nur dann zu einer intensiveren Weinfarbe führt, wenn das Verhältnis von Tanninen zu Anthocyanen (TAV) unter einem Wert von 3 lag. Die Zunahme der Farbintensität war außerdem negativ mit den spektralphotometrisch zu bestimmenden kleinen (SPP) und großen polymeren Pigmenten (LPP) korreliert, sodass Sauerstoff nur bei geringen Konzentrationen dieser Pigmente zu höheren Farbintensitäten führte. Zudem wurde während der Mikrooxygenierung keine weitere Intensivierung der Weinfarbe erzielt, wenn der Gehalt der LPP den der SPP überstieg. Da LPP aufgrund ihrer Molekülgröße auch eine geringere Löslichkeit aufweisen, sollte ihre übermäßige Bildung vermieden werden. Die Bestimmung von TAV, SPP und LPP erlaubt es somit, die Wirkung von Sauerstoff auf die Weinfarbe vor der Anwendung der Mikrooxygenierung einschätzen und den Sauerstoffzusatz zu beenden, wenn aufgrund der analytischen Daten eine weitere Steigerung der Farbintensität nicht zu erwarten ist.
In einem weiteren Teil der Arbeit wurde untersucht, wie sich die Mikrooxygenierung auf die Lagerfähigkeit der Rotweine auswirkt, da Sauerstoff zu einer beschleunigten Reifung führen kann. Dabei zeigte sich, dass die Farbe des mikrooxygenierten Weines auch nach einer 12-monatigen Flaschenlagerung noch stabiler war als in der entsprechenden Kontrollvariante und der Effekt damit nachhaltig. In Geruch und Geschmack unterschied sich der mikrooxygenierte Wein hingegen nicht von der Kontrolle. Mikrooxygenierte Weine sind damit ebenso lagerfähig, wie ohne Sauerstoffzugabe erzeugte Weine.