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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.
Various physical phenomenons with sudden transients that results into structrual changes can be modeled via
switched nonlinear differential algebraic equations (DAEs) of the type
\[
E_{\sigma}\dot{x}=A_{\sigma}x+f_{\sigma}+g_{\sigma}(x). \tag{DAE}
\]
where \(E_p,A_p \in \mathbb{R}^{n\times n}, x\mapsto g_p(x),\) is a mapping, \(p \in \{1,\cdots,P\}, P\in \mathbb{N}
f \in \mathbb{R} \rightarrow \mathbb{R}^n , \sigma: \mathbb{R} \rightarrow \{1,\cdots, P\}\).
Two related common tasks are:
Task 1: Investigate if above (DAE) has a solution and if it is unique.
Task 2: Find a connection among a solution of above (DAE) and solutions of related
partial differential equations.
In the linear case \(g(x) \equiv 0\) the task 1 has been tackeled already in a
distributional solution framework.
A main goal of the dissertation is to give contribution to task 1 for the
nonlinear case \(g(x) \not \equiv 0\) ; also contributions to the task 2 are given for
switched nonlinear DAEs arising while modeling sudden transients in water
distribution networks. In addition, this thesis contains the following further
contributions:
The notion of structured switched nonlinear DAEs has been introduced,
allowing also non regular distributions as solutions. This extend a previous
framework that allowed only piecewise smooth functions as solutions. Further six mild conditions were given to ensure existence and uniqueness of the solution within the space of piecewise smooth distribution. The main
condition, namely the regularity of the matrix pair \((E,A)\), is interpreted geometrically for those switched nonlinear DAEs arising from water network graphs.
Another contribution is the introduction of these switched nonlinear DAEs
as a simplication of the PDE model used classically for modeling water networks. Finally, with the support of numerical simulations of the PDE model it has been illustrated that this switched nonlinear DAE model is a good approximation for the PDE model in case of a small compressibility coefficient.
Anwenderunterstützung bei der Nutzung und Überprüfung von optischen 3D-Oberflächenmessgeräten
(2019)
Technische Oberflächen werden mit immer komplexeren, dreidimensionalen Strukturen hergestellt, um gewünschte Funktionseigenschaften zu erhalten. Mit taktilen Rauheitsmessgeräten lassen sich diese allerdings nur schwer charakterisieren. Besser eignen sich hierfür optische Rauheitsmessgeräte, die die Oberfläche flächenhaft erfassen können. Diese unterscheiden sich allerdings in ihren Eigenschaften und Einstellungen von den in der Industrie bekannten und bewährten taktilen Systemen. Daher wird in dieser Arbeit ein Assistenzsystem vorgestellt, das die Anwender unterstützt, ihr optisches Rauheitsmessgerät sicher und normgerecht nach DIN EN ISO 25178 einzusetzen.Das Assistenzsystem führt Schritt für Schritt durch die Planung einer Messaufgabe, durch die Überprüfung zur Kontrolle der korrekten Funktion des Gerätes und der Eignung für die Messaufgabe, und im letzten Schritt durch die normgerechte Auswertung der Messung, um die gewünschten 3D-Oberflächenkennwerte zu erhalten.
The usage of sensors in modern technical systems and consumer products is in a rapid increase. This advancement can be characterized by two major factors, namely, the mass introduction of consumer oriented sensing devices to the market and the sheer amount of sensor data being generated. These characteristics raise subsequent challenges regarding both the consumer sensing devices' reliability and the management and utilization of the generated sensor data. This thesis addresses these challenges through two main contributions. It presents a novel framework that leverages sentiment analysis techniques in order to assess the quality of consumer sensing devices. It also couples semantic technologies with big data technologies to present a new optimized approach for realization and management of semantic sensor data, hence providing a robust means of integration, analysis, and reuse of the generated data. The thesis also presents several applications that show the potential of the contributions in real-life scenarios.
Due to the broad range, growing feature set and fast release pace of new sensor-based products, evaluating these products is very challenging as standard product testing is not practical. As an alternative, an end-to-end aspect-based sentiment summarizer pipeline for evaluation of consumer sensing devices is presented. The pipeline uses product reviews to extract the sentiment at the aspect level and includes several components namely, product name extractor, aspects extractor and a lexicon-based sentiment extractor which handles multiple sentiment analysis challenges such as sentiment shifters, negations, and comparative sentences among others. The proposed summarizer's components generally outperform the state-of-the-art approaches. As a use case, features of the market leading fitness trackers are evaluated and a dynamic visual summarizer is presented to display the evaluation results and to provide personalized product recommendations for potential customers.
The increased usage of sensing devices in the consumer market is accompanied with increased deployment of sensors in various other fields such as industry, agriculture, and energy production systems. This necessitates using efficient and scalable methods for storing and processing of sensor data. Coupling big data technologies with semantic techniques not only helps to achieve the desired storage and processing goals, but also facilitates data integration, data analysis, and the utilization of data in unforeseen future applications through preserving the data generation context. This thesis proposes an efficient and scalable solution for semantification, storage and processing of raw sensor data through ontological modelling of sensor data and a novel encoding scheme that harnesses the split between the statements of the conceptual model of an ontology (TBox) and the individual facts (ABox) along with in-memory processing capabilities of modern big data systems. A sample use case is further introduced where a smartphone is deployed in a transportation bus to collect various sensor data which is then utilized in detecting street anomalies.
In addition to the aforementioned contributions, and to highlight the potential use cases of sensor data publicly available, a recommender system is developed using running route data, used for proximity-based retrieval, to provide personalized suggestions for new routes considering the runner's performance, visual and nature of route preferences.
This thesis aims at enhancing the integration of sensing devices in daily life applications through facilitating the public acquisition of consumer sensing devices. It also aims at achieving better integration and processing of sensor data in order to enable new potential usage scenarios of the raw generated data.
Many loads acting on a vehicle depend on the condition and quality of roads
traveled as well as on the driving style of the motorist. Thus, during vehicle development,
good knowledge on these further operations conditions is advantageous.
For that purpose, usage models for different kinds of vehicles are considered. Based
on these mathematical descriptions, representative routes for multiple user
types can be simulated in a predefined geographical region. The obtained individual
driving schedules consist of coordinates of starting and target points and can
thus be routed on the true road network. Additionally, different factors, like the
topography, can be evaluated along the track.
Available statistics resulting from travel survey are integrated to guarantee reasonable
trip length. Population figures are used to estimate the number of vehicles in
contained administrative units. The creation of thousands of those geo-referenced
trips then allows the determination of realistic measures of the durability loads.
Private as well as commercial use of vehicles is modeled. For the former, commuters
are modeled as the main user group conducting daily drives to work and
additional leisure time a shopping trip during workweek. For the latter, taxis as
example for users of passenger cars are considered. The model of light-duty commercial
vehicles is split into two types of driving patterns, stars and tours, and in
the common traffic classes of long-distance, local and city traffic.
Algorithms to simulate reasonable target points based on geographical and statistical
data are presented in detail. Examples for the evaluation of routes based
on topographical factors and speed profiles comparing the influence of the driving
style are included.
Ultrahochfester Beton (UHB oder aus dem Englischen Ultra High Performance Concrete, kurz UHPC) weist eine Druckfestigkeit im Bereich von 150 bis 250 MPa auf. Eine gesteigerte Zugfestigkeit und ein duktiles Verhalten werden durch die Zugabe von Mikrostahlfasern erzielt (Ultra High Performance Fibre Reinforced Concrete, UHPFRC). Der Fasergehalt ist in der Regel höher als bei normalfestem Faserbeton, sodass aufgrund der Fasern ein „Strain-hardening“ Verhalten erreicht werden kann: in einem Biegezugversuch kann die Last nach der Erstrissbildung weiter gesteigert werden bis zur Ausbildung mehrerer feiner Risse. Da der Beitrag der Fasern zum Zugtragverhalten des UHPFRC ein wesentlicher ist, müssen die Bauteile im gerissenen Zustand bemessen werden. Während der statische und dynamische Widerstand bereits umfangreich untersucht wurde, liegen nur wenige Untersuchungen bezüglich das Dauerstandzugverhaltens von gerissenem ultrahochfestem Beton vor. Untersuchungen an normalfestem faserverstärktem Beton haben gezeigt, dass die zeitabhängigen Zugverformungen im gerissenen Zustand größer sind als die in ungerissenem Material.
Um die zu erwartenden Verformungen abschätzen zu können und um das Kriechverhalten des Materials bis zum Versagen zu analysieren, wurde im Rahmen dieser Arbeit ein umfangreiches Versuchsprogramm durchgeführt. Über 60 uniaxiale Zug- und Biegezugprobekörper wurden unter Dauerlast über einen Zeitraum von bis zu 15 Monaten beansprucht. Davon wurden 22 Probekörper nach vier Monaten hinsichtlich ihrer Resttragfähigkeit getestet. Die restlichen Probekörper befinden sich für Langzeit-Messungen weiterhin in den Dauerlastprüfständen. Es wurden dabei verschiedene Parameter untersucht: u.a. das Belastungsniveau, Art und Umfang der Nachbehandlung des Betons, das Betonalter zu Beginn der Belastung, der Fasergehalt und die Faserschlankheit. Das Schwinden der unbelasteten Probekörper sowie das Druckkriechen belasteter Probekörper wurden an der verwendeten Mischung gemessen.
Der UHPFRC wies im Allgemeinen ein sehr stabiles Verhalten auf und es zeigte sich keine unkontrollierte Zunahme der Verformungen infolge eines Faserauszugs. Lediglich bei einem Probekörper kam es bei einer Last von 79% der aufgebrachten Last am Ende der Vorbelastung zum Versagen. Der Autor sieht dabei eine ungünstige Faserausrichtung als mögliche Ursache des frühzeitigen Versagens des Probekörpers an, was auf einen bedeutenden Einfluss dieses Parameters auf die Tragfähigkeit schließen lässt. Hinsichtlich der Bemessung von gerissenen UHPFRC-Bauteilen unter Dauerlast wurde ein Vorschlag für die Bemessung der Dauerstandfestigkeit ausgearbeitet.
Darüber hinaus wurden Faserauszugversuche durchgeführt und das Verbund-Schlupfverhalten der verwendeten Fasern ermittelt. Einige Probekörper wurden nach uniaxialen Zugversuchen per Computertomographie gescannt, um den Zusammenhang der Fasern im Versagensquerschnitt zur Zugfestigkeit der Probekörper zu untersuchen. Die untersuchten Probekörper wiesen unterschiedliche Zugfestigkeiten auf. Diese konnten durch die verschiedenen Faseranzahlen im Versagensquerschnitt gut abgebildet werden.
Der Werkstoff Sheet Molding Compound (SMC) wurde in den 1960er Jahren entwickelt
und ermöglichte erstmals die großserientaugliche Herstellung von Faser-
Kunststoff-Verbund (FKV) Bauteilen. Heutzutage werden ca. 20 % aller in Europa
hergestellten Glasfasern in diesem Verfahren zu FKV verarbeitet. Die ökologischen
und ökonomischen Anforderungen an FKV-Bauteile steigen kontinuierlich. Es werden
immer leichtere, mechanisch höher belastbare und auch bio-basierte Pendants zu
bekannten Lösungen gefordert. Im Rahmen dieser Arbeit wurde der Einsatz von biobasierten
und nachwachsenden Rohstoffen als alternative Füllstoffe für duroplastische
SMC-Halbzeuge untersucht. Die Verarbeitung der alternativen Füllstoffe in
SMC-Halbzeugen darf keine negativen Einflüsse auf die Produktions- und Verarbeitungsabläufe
mit sich bringen. Weiterhin soll durch den Einsatz der alternativen Füllstoffe
eine Dichtereduktion um ca. 15 %, bei gleichbleibenden mechanischen Eigenschaften,
erreicht werden. Die Verwendung der bio-basierten und nachwachsenden
Füllstoffe darf nicht in Konkurrenz zur Nahrungsmittelindustrie stehen.
Zu Beginn der Arbeit wurden in Kooperation mit SMC-Experten und SMC-Herstellern
die Spezifikationen und Anforderungen an ein Standard-SMC definiert. Anschließend
wurde ein SMC-Halbzeug auf Basis eines ungesättigten Polyesterharzes, konventioneller
mineralischer Füllstoffe und Glasfasern entwickelt. Dieses Halbzeug erfüllt mit
einer Dichte von 1,95 g/cm³, einem E-Modul von 10,4 GPa und einer Zugfestigkeit
von 100 MPa die geforderten Spezifikationen und diente im weiteren Verlauf der Arbeit
als Referenz.
Im Rahmen der Arbeit wurde nachgewiesen, dass die Verarbeitung von bio-basierten
und nachwachsenden Rohstoffen eine Adaption der zuvor entwickelten Harzpaste
erfordert und Sonnenblumenkernschalenmehl als Füllstoff die konventionellen Füllstoffe
zu 100 % ersetzen kann. Die resultierende Halbzeugdichte beträgt 1,55 g/cm³
und liegt damit 20 % unter dem Referenzmaterial. Sowohl die mechanischen Kennwerte
(E-Modul 10,8 GPa und Zugfestigkeit 96 MPa) als auch die Herstellung und
Verarbeitung der Harzpaste erreichen die Referenzwerte und sind mit konventionellen
Halbzeugen vergleichbar. Im Rahmen der Arbeit konnte somit die Tauglichkeit
bio-basierter und nachwachsender Füllstoffe für einen möglichen Serieneinsatz in
SMC-Halbzeugen nachgewiesen werden.
Sheet Molding Compound (SMC) was developed in the 1960s and initially enabled
the production of glass fiber reinforced polymer composite (GFRPC) in mass scale
production. Nowadays, both material and process are well established for the production
of semi-structural components in various applications from construction industry
to automotive components. Currently, approximately 20% of all glass fibers produced
in Europe are processed to SMC. Increasing strict ecological and economical requirements
for construction materials, force further development of SMC in order to
strengthen its sales markets and open up new ones.
The objective of this work is the development of a SMC semi-finished product, using
bio-based and renewable materials as alternative filler materials. The processing of
the alternative fillers must not have any negative influence on the production and
processing procedures. Furthermore, the use of alternative fillers should achieve a
density reduction of 15% while maintaining the same mechanical properties. The use
of bio-based and renewable fillers must not compete with the food industry.
At first, specifications and requirements for a standard SMC were defined in cooperation
with SMC experts and producers. Afterwards a SMC semi-finished product
based on unsaturated polyester resin, glass fibers and conventional mineral fillers
was developed. With a density of 1.95 g/cm³, a Young’s modulus of 10.4 GPa and a
tensile strength of 100 MPa this SMC fulfills the specifications and is used as a reference
for further development.
In a second step a SMC with bio-based and renewable fillers was developed. This
work proofs the complete replacement of conventional filler materials by bio-based
and renewable filler materials. Therefore an adaption of the resin paste is necessary.
The best results were achieved with a resin paste using sunflower hulls flour as filler
material. The resulting semi-finished product shows a density of 1.55 g/cm³ and both
processability and mechanical properties are comparable to conventional SMC materials With a fiber mass content of 30% by weight, a Young’s modulus of 10.8 GPa
and a tensile strength of 96 MPa are achieved.
Die Dissertation mit dem Titel „bio-psycho-soziale Gesundheit der Studierenden der TU Kaiserslautern“ ist auf dem Hintergrund der Frage entstanden, wie die Gesundheit von Studierenden erhalten und gefördert werden kann. Die Gesundheitsprävention hat auch im Bereich der Hochschulen in den letzten Jahren erheblich an Bedeutung gewonnen, einerseits durch die steigende Anzahl psychischer Erkrankungen bei Studierenden, andererseits durch die Umsetzung des Präventionsgesetzes, das am 01.01.2016 in Kraft getreten ist. Die Arbeit gibt zentrale Hinweise auf Belastungen und Beanspruchungen von Studierenden der TUK und zeigt einen möglichen Weg zum Aufbau eines systematischen Gesundheitsmanagements an einer Universität. Unterfüttert anhand konkreter Beispiele aus der Praxis wird dargestellt, wie Präventionsmaßnahmen im Setting Universität durchgeführt werden können. Ein Beitrag zur Gesundheitsberichterstattung von Studierenden wird durch unterschiedliche Darstellungen zentraler Ergebnisse die Gesundheit der Studierenden betreffend geleistet. Im empirischen Teil der Arbeit werden sechs Hypothesen überprüft die anhand eines definierten Merkmalskanons Zusammenhänge und Unterschiede unterschiedlicher gesundheitsrelevanter Facetten herausarbeiten. Im Konkreten sind dies die Konstrukte Depressives Syndrom, Stress, Erschöpfung, Burnout, Engagement, soziale Unterstützung, allgemeine Lebenszufriedenheit in Kombination mit der Studienphase (Bachelor vs. Master), dem Hochschulsemester, Genderaspekten, körperlicher Aktivität sowie dem Leistungsumfang im Studium.
Carotenoids are organic lipophilic tetraterpenes ubiquitously present in Nature and found across the three domains of life (Archaea, Bacteria and Eukaryotes). Their structure is characterized by an extensive conjugated double-bond system, which serves as a light-absorbing chromophore, hence determining its colour, and enables carotenoids to absorb energy from other molecules and to act as antioxidant agents. Humans obtain carotenoids mainly via the consumption of fruits and vegetables, and to a smaller extent from other food sources such as fish and eggs. The concentration of carotenoids in the human plasma and tissues has been positively associated with a lower incidence of several chronic diseases including, cancer, diabetes, macular degeneration and cardiovascular conditions, likely due to their antioxidant properties. However, an important aspect of carotenoids, namely β- and α-carotene and β-cryptoxanthin, in human health and development, is their potential to be converted by the body into Vitamin A.
Yet, bioavailability of carotenoids is relatively low (< 30%) and dependent, among others, on dietary factors, such as amount and type of dietary lipids and the presence of dietary fibres. One dietary factor that has been found to negatively impact carotenoid bioaccessibility and cellular uptake in vitro is high concentrations of divalent cations during simulated gastro-intestinal digestion. Nevertheless, the mechanism of action of divalent cations remains unclear. The goal of this thesis was to better understand how divalent cations act during digestion and modulate carotenoid bioavailability. In vitro trials of simulated gastro-intestinal digestion and cellular uptake were run to investigate how varying concentrations of calcium, magnesium and zinc affected the bioaccessibility of both pure carotenoids and carotenoids from food matrices. In order to validate or refute results obtained in vitro, a randomized and double blinded placebo controlled cross-over postprandial trial (24 male participants) was carried out, testing the effect of 3 supplementary calcium doses (0 mg, 500 mg and 1000 mg) on the bioavailability of carotenoids from a spinach based meal. In vitro trials showed that addition of the divalent cations significantly decreased the bioaccessibility of both pure carotenoids (P < 0.001) and those from food matrices (P < 0.01). This effect was dependent on the type of mineral and its concentration. Strongest effects were seen for increasing concentrations of calcium followed by magnesium and zinc. The addition of divalent cations also altered the physico-chemical properties, i.e. viscosity and surface tension, of the digestas. However, the extent of this effect varied according to the type of matrix. The effects on bioaccessibility and physico-chemical properties were accompanied by variations of the zeta-potential of the particles in solution. Taken together, results from the in vitro trials strongly suggested that divalent cations were able to bind bile salts and other surfactant agents, affecting their solubility. The observed i) decrease in macroviscosity, ii) increase in surface tension, and the iii) reduction of the zeta-potential of the digesta, confirmed the removal of surfactant agents from the system, most likely due to precipitation as a result of the lower solubility of the mineral-surfactant complexes. As such, micellarization of carotenoids was hindered, explaining their reduced bioaccessibility. As for the human trial, results showed that there was no significant influence of supplementation with either 500 or 1000 mg of supplemental calcium (in form of carbonate) on the bioavailability of a spinach based meal, as measured by the area-under curve of carotenoid concentrations in the plasma-triacylglycerol rich fraction, suggesting that the in vitro results are not supported in such an in vivo scenario, which may be explained by the initial low bioaccessibility of spinach carotenoids and the dissolution kinetics of the calcium pills. Further investigations are necessary to understand how divalent cations act during in vivo digestion and potentially interact with lipophilic nutrients and food constituents.
Large-scale distributed systems consist of a number of components, take a number of parameter values as input, and behave differently based on a number of non-deterministic events. All these features—components, parameter values, and events—interact in complicated ways, and unanticipated interactions may lead to bugs. Empirically, many bugs in these systems are caused by interactions of only a small number of features. In certain cases, it may be possible to test all interactions of \(k\) features for a small constant \(k\) by executing a family of tests that is exponentially or even doubly-exponentially smaller than the family of all tests. Thus, in such cases we can effectively uncover all bugs that require up to \(k\)-wise interactions of features.
In this thesis we study two occurrences of this phenomenon. First, many bugs in distributed systems are caused by network partition faults. In most cases these bugs occur due to two or three key nodes, such as leaders or replicas, not being able to communicate, or because the leading node finds itself in a block of the partition without quorum. Second, bugs may occur due to unexpected schedules (interleavings) of concurrent events—concurrent exchange of messages and concurrent access to shared resources. Again, many bugs depend only on the relative ordering of a small number of events. We call the smallest number of events whose ordering causes a bug the depth of the bug. We show that in both testing scenarios we can effectively uncover bugs involving small number of nodes or bugs of small depth by executing small families of tests.
We phrase both testing scenarios in terms of an abstract framework of tests, testing goals, and goal coverage. Sets of tests that cover all testing goals are called covering families. We give a general construction that shows that whenever a random test covers a fixed goal with sufficiently high probability, a small randomly chosen set of tests is a covering family with high probability. We then introduce concrete coverage notions relating to network partition faults and bugs of small depth. In case of network partition faults, we show that for the introduced coverage notions we can find a lower bound on the probability that a random test covers a given goal. Our general construction then yields a randomized testing procedure that achieves full coverage—and hence, find bugs—quickly.
In case of coverage notions related to bugs of small depth, if the events in the program form a non-trivial partial order, our general construction may give a suboptimal bound. Thus, we study other ways of constructing covering families. We show that if the events in a concurrent program are partially ordered as a tree, we can explicitly construct a covering family of small size: for balanced trees, our construction is polylogarithmic in the number of events. For the case when the partial order of events does not have a "nice" structure, and the events and their relation to previous events are revealed while the program is running, we give an online construction of covering families. Based on the construction, we develop a randomized scheduler called PCTCP that uniformly samples schedules from a covering family and has a rigorous guarantee of finding bugs of small depth. We experiment with an implementation of PCTCP on two real-world distributed systems—Zookeeper and Cassandra—and show that it can effectively find bugs.