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Synchronization of Manufacturing Systems: Definition, Measurement, Triggers and Effects
No full textThe term ‘synchronization’ in manufacturing refers to the provision of the right components to the subsequent production steps at the right moment in time. It is assumed that synchronization is beneficial to the logistics performance (LP) of manufacturing systems (MS). However, in the field of natural sciences synchronization is seen as the adjustment of rhythms due to interaction and it has been shown that synchronization phenomena can be detrimental to systems in which they emerge. Hence, the aim of this thesis is to investigate how synchronization can be explored to achieve better LP in MS. In a first step, a formal quantification and holistic understanding of the types of synchronization phenomena emerging in MS is established by transferring knowledge from the field of natural sciences. Further, an analysis of real-world production data and a discrete-event simulation study are applied to investigate the cause-and-effect relationships between the MS properties and synchronization emergence as well as LP.
Two distinct synchronization types occurring in MS are defined, logistics and physics synchronization, and appropriate quantification measures for each of them are developed. Moreover, both structural and dynamic MS parameters are identified as factors triggering synchronization emergence in MS. Network properties of the material flow network (structural property) as well as processing time variability and workload level (dynamic properties) are found to influence emergence. Furthermore, the investigation of synchronization’s relation to LP shows that it is not straightforward and depends on different factors. Four LP indicators are studied: short throughput times, low WIP levels, high due date performance (DDP) and high capacity utilisation. It is shown that both logistics and physics synchronization phenomena relate positively to LP in most cases. However, depending on the MS and the specific DDP measure, for example, they can also have negative effects
On the pseudoconcavity of flag domains
No full textFlag domains are by definition open orbits of real forms of complex semisimple groups in flag manifolds . Every maximal compact subgroup has a unique orbit in which is a complex submanifold. Since can be moved with the group action, it is rare that possesses non-constant holomorphic functions. For example, if is cycle connected i.e., any two points can be connected by a chain of translates of , then . In a 2010 paper of A. Huckleberry entitled "Remarks on homogeneous complex manifolds satisfying Levi conditions" it is shown , absence of cycle connectivity and pseudoconvexity (in the sense of plurisubharmonic exhaustions) are equivalent conditions. There it is conjectured that if one of these equivalent conditions is not fulfilled, then it is pseudoconcave in the sense of A. Andreotti. This conjecture is proved here. Rough estimates of the degree of pseudoconcavity are proved in general and explicit computations of various cycle- and curve-connectivity properties of -flag domains are carried out
Molecular Basis of Gating and Permeation in Bacterial Outer Membrane Channels
No full textBacterial outer membrane (OM) channels are of major pharmaceutical interest
in the field of infectious diseases, since they act as gateways for the influx of
antibiotics. The research work reported in this thesis is aimed at understanding the common principles in the functionality of these channels from a molecular perspective.
In the first part, we dealt with the nutrient acquisition mechanisms by a OM transporter complex. SusCD, a transporter from Bacteroides thetaiotaomicron, was investigated using MD simulations. Bacteroides species are highly populated in the human large intestine and plays a significant role in digestion and obesity. The survival of these organisms depend on their ability to acquire undigested nutrients from the highly competitive gut environment by OM transporter complexes. In this thesis, we presented a generalized mechanism for the nutrient acquisition by SusCD-like OM complexes. MD simulations revealed a "pedal-bin mechanism" for the particular SusCD transport machine which could be applicable to other transporters. Given the unknown specific functions of many OM proteins, this study improves the molecular understanding of transport mechanisms by OM transporters.
The second part of the thesis aimed at understanding functional properties, i.e., gating and selective nutrient uptake, of passive diffusion channels. These channels are dynamic and exists in multiple pore sizes to control the influx of nutrients across the OM. MD simulations identified the crucial residue driving the opening and closing of the OpdH channel. Furthermore, we investigated the functional role and selective uptake mechanism of OpdH channel using MD simulations. Free-energy calculations revealed thermodynamic insights into the selective uptake mechanism of the OpdH channel and its preference for the uptake of succinate from the environment. Our results show that OpdH selectivity can be explained on the basis of "size-exclusion" principle
Engineering Saccharomyces cerevisiae for the production of 1,2-propanediol using glycerol as a carbon and energy source
No full textBiodiesel production via transesterification generates approx. 10% (w/w) glycerol, which is considered as a glut and needs to be valorized. The production of 1,2-propanediol (1,2-PDO) could prove to be one interesting valorization route. 1,2-PDO is an important commodity chemical used in food, drug, and cosmetic industries. Beside these applications, its frequent use as a less-toxic (compared to ethylene glycol) antifreeze, as a favorable solvent in photographic industries, in polyester resin preparation, and in preparation of biodegradable plastics makes it a chemical in high demand.
S. cerevisiae is one of the favored platforms for metabolic engineering and a popular microbial host to produce high-value chemicals. In this study we attempt engineering S. cerevisiae for 1,2-PDO production from glycerol. As a starting point we used a previously selected S. cerevisiae strain (CBS 6412-13A) naturally able to grow on glycerol with μmax of ∼0.13 h-1. First, the glycerol growth of CBS6412-13A on glycerol was further improved by ∼39%, reaching to a μmax of ∼0.18 h-1 by expressing a heterologous glycerol facilitator (Fps1p from Cyberlindnera jadinii).
In order to produce 1,2-PDO in the latter strain, three heterologous 1,2-PDO pathway enzymes were co-expressed. As the 1,2-PDO pathway enzyme need redox equivalent in the form of NADH, the native glycerol catabolic pathway was replaced by an NADH generating pathway. To further enhance the 1,2-PDO production in such an engineered strain, the triose phosphate isomerase that competes with 1,2-PDO pathway for dihydroxyacetone phosphate was down-regulated by replacing the native TPI1 promoter by the weak promoter TEFmut2. Additionally, the key genes encoding the heterologous 1,2-PDO pathway enzymes were overexpressed by introducing their second copies into the genome. The reduction of Tpi1p activity in combination with NADH-generating glycerol catabolic pathway and overexpression of key 1,2-PDO enzymes resulted in a remarkable improvement of 1,2-PDO production from glycerol and a titer of ~3.7 g/L was achieved. This concentration of 1,2-PDO is the highest ever achieved (~70% more than previously reported) in engineered S. cerevisiae using glycerol as a carbon source
Powerline Transmission System for Underwater Sensor Networks
No full textThe major contribution of this work is a novel powerline communication
system for underwater acoustical sensor networks. Sonar is the best example
of such a network, which has a linear bus topology. There is a number of
challenges for a transmission system in this particular application. A high
data volume, generated by numerous acoustical sensors, the requirements of
high synchronization accuracy and low power consumption, changing channel
conditions and a high level of inter-symbol interference, caused by the multi-
path nature of a linear bus, are among the problems solved by the suggested
multi-carrier transmission system
Categories O for Dynkin Borel Subalgebras of Root-Reductive Lie Algebras
No full textThe purpose of my Ph.D. research is to define and study an analogue of the classical
Bernstein-Gelfand-Gelfand (BGG) category O for the Lie algebra g, where g is one of the
finitary, infinite-dimensional Lie algebras gl(∞,K), sl(∞,K), so(∞,K), and sp(∞,K). Here, K is an algebraically closed field of characteristic 0. We call these categories extended categories O and use the notation Ō. While the categories Ō are defined for all splitting Borel subalgebras of g, this research focuses on the categories Ō for very special Borel subalgebras of g which we call Dynkin Borel subalgebras. Some results concerning block decomposition and Kazhdan-Lusztig multiplicities carry over from usual categories O to our categories Ō. There are differences which we shall explore in detail, such as the lack of some injective hulls. In this connection, we study truncated categories Ō and are able to establish an analogue of BGG reciprocity in the categories Ō
SQL Support for Multidimensional Arrays
No full textMultidimensional arrays represent a core underlying structure of manifold science and engineering data. It is generally recognized today, therefore, that arrays have an essential role in Big Data and should become an integral part of the overall data type orchestration in information systems. This Technical Report discusses the support for Multidimensional Arrays (MDA) as defined in ISO9075-15
Pathogen Detection on “Point-of-Care” Systems
No full textA fast and reliable diagnosis is the key factor in the management of patients with infectious diseases. Most diagnostic samples are sent to central laboratories, which are equipped with extensive laboratory infrastructure and staffed with highly trained personnel. This leads to very reliable results. However the turnaround time, i.e., the time from taking the sample from the patient to the time until the physician gets the result, can be hours to days. Therefore, there is an urgent need for fast and reliable diagnostic systems near the patient (at the physician’s office, in small hospitals, in emergency rooms, etc.) that are optimized for highly reliable and fast diagnosis. Point-of-care (POC) diagnostics attempt to bring the diagnostic near the side of the patient.
The aim of this doctoral thesis “Pathogen Detection on Point-of-Care Systems” was to develop and optimize biochemical procedures needed for the fast and reliable POC molecular diagnostic systems for pathogen detection near the patient. The PhD study was part of multiple externally funded projects dealing with the development of in-vitro diagnostic systems near patient. The work packages of this thesis comprised (i) the engineering and production of an inhibitor tolerant DNA Polymerase, (ii) the development, optimization and combination of Nested-PCR based detection assays for sexually transmitted diseases (STD) pathogen panel, a bacterial respiratory panel and a VRE panel, (iii) the development of a pretreatment and inhibitor tolerant pre-amplification buffers, (iiii) the implementation of the reaction chemistry into an POC workflow.
The principal suitability of the direct PCR workflow, developed during this PhD thesis for POC molecular diagnostic testing, could be demonstrated
Resource changes and cooperative behavior
No full textHow do changes in the resources influence the individual behavior? This dissertation aims at answering this question by using laboratory experiments to investigate the behavior of actors that face considerable changes in the environment they are acting in.
Resource changes and resource stock levels in common-pool resources have received relatively little attention by academic research so far, even though, in the modern world, the distribution of resources is in constant change, be it drastic or gradual. We are continuously observing changes in the resource balance across the world, with the menace of even greater changes in the future, both global (e.g. climate change) and local (e.g. natural disasters). Given these premises, knowing which conduct to expect from the resource users across the world in those cases is certainly useful in order to be able to ensure that future policies will be able to reduce the possible non-cooperative, and unsustainable behavior that could arise in such situations.
This research tackles these aspects of cooperation in the management of common resources by conducting three laboratory experiments, using two different experimental tools. We tried to recreate in a controlled situation the challenges that changes in ecosystems pose to people in sensitive areas and examine how they react to gradual changes or sudden shocks, and how trust between actors and tendency to adopt cooperative strategies may vary.
The first objective of this work is, as already mentioned, to investigate which reactions can be expected from resource users that face different types of resource changes, to pinpoint which of these changes can be critical hindrances for sustainable management. The second objective is to improve experimental research on this topic, by introducing in the experimental environment several ecological aspects, i.e. regeneration patterns, spatial distribution, and time continuous interactions, which have not been extensively studied as of yet
Elucidating the role of cell-to-cell heterogeneity in acetic acid tolerance of the yeast Saccharomyces cerevisiae
No full textIt was shown recently that individual cells of an isogenic S. cerevisiae population show variability in acetic acid tolerance, and this variability affects the quantitative manifestation of the trait at the population level. In the current thesis, we investigated whether cell-to-cell variability in acetic acid tolerance could be explained by the observed differences in the cytosolic pH of individual cells immediately before exposure to the acid. Results obtained with cells of the strain CEN.PK113-7D in synthetic medium containing 96 mM acetic acid (pH 4.5) showed a direct correlation between the initial cytosolic pH and the cytosolic pH drop after exposure to the acid. Moreover, only cells with a low initial cytosolic pH, which experienced a less severe drop in cytosolic pH, were able to proliferate. A similar correlation between initial cytosolic pH and cytosolic pH drop was also observed in the more acid tolerant strain MUCL 11987-9. Interestingly, a fraction of cells in the MUCL 11987-9 population showed initial cytosolic pH values below the minimal cytosolic pH detected in cells of the strain CEN.PK113-7D; consequently, these cells experienced less severe drops in cytosolic pH. Although this might explain in part the difference between the two strains with regard to the number of cells that resume proliferation, it was observed that all cells from strain MUCL 11987-9 were able to proliferate, independent of their initial cytosolic pH. Therefore, other factors must also be involved in the greater ability of MUCL 11987-9 cells to endure strong drops in cytosolic pH