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On the Integration of Array and Relational Models in Databases
No full textArray databases are a quickly expanding category of database management systems that treat large multidimensional arrays as first-class database citizens. Array data itself is almost always linked to additional, non-array information, but this is not adequately handled in today’s systems. Array databases specialize in the management of array data, while other systems, e.g. relational DBMS, have at best only very basic support for arrays. As a result, handling array data in practice most often requires either multiple DBMS with manual data integration and synchronization, or dedicated solutions constrained to a narrow domain.
This thesis addresses this situation by extending the relatonal data model with support for multidimensional arrays in a non-intrusive way that is orthogonal to its set semantics. The array model itself is declarative, optimizable, and minimal, yet powerful enough for application domains in science, engineering, and business. The algebraic formalization is materialized into an official standard ISO SQL extension known as SQL/MDA. A proof of concept mediator implementation of SQL/MDA – utilizing a new array processing engine optimized for modern hardware and a standard relational DBMS – demonstrates practical feasibility of the established concepts. All in all, this thesis covers in completeness the topic of array / relation integration in databases and presents a theoretically sound and practically viable solution
Surface Patches with Uncertainties for 3D Object Recognition and 3D Mapping with Noisy Sensors
No full textSpatial perception capability is a fundamental requirement for autonomous intelligent robots to be effective in real world scenarios. Modern robots are deployed in unstructured and increasingly complex environments. In such environments, 3D perception is indispensable for autonomous robot activities such as mapping, localization, recognition, modeling, manipulation, etc. With the advancement made in 3D sensing technologies these tasks have become more manageable in terms of accuracy and computation time.
Typical 3D range sensors produce a point-cloud. This is a set of 3D points computed from the ranges to the nearest obstacles along a 2D raster of beam directions. Point-clouds are the most commonly used representation in 3D perception algorithms, especially in mapping.
This thesis investigates an alternative approach to 3D perception and mapping, which is based on surface patches extracted from noisy range measurements. This approach offers many advantages in terms of storage requirements, noise reduction, computational efficiency, and semantic interpretation of the environment. However, it also raises new challenges. Many of these challenges are addressed in this thesis within the context of 3D mapping and object recognition for manipulation tasks.
In the first part of the thesis, contributions to surface segmentation and surface fitting with uncertainty estimation for 3D mapping are presented. In the second part of the thesis, a scenario focused on object recognition and localization in the context of autonomous container unloading is considered.
The theoretical contributions presented in this thesis are substantiated by experiments on real-world data. Moreover, the majority of algorithms have been successfully integrated in autonomous robotic demonstrators, thus demonstrating their applicability to realistic scenarios
Solution Processed 2D Transition Metal Dichalcogenides and Electrical Properties of TMD Thin Film Transistors
No full textAs the device performance based on silicon technologies is approaching their physical limits, solutions based on alternative semiconducting materials are being considered. Low dimension materials with large lateral size are prerequisites for next generation electronics. Layered transition metal dichalcogenides (TMDs) have been demonstrated to be a promising candidate, especially after the first single layer (~ 0.65 nm) MoS2 transistor reported by Kis’s group in 2011. TMDs have shown potential applications in many fields. However, the development of large scale and low-cost growth techniques is a crucial step towards TMDs inclusion in modern electronics. Moreover, there is a large interest in establishing cheap, scalable processes for device fabrication based on those low dimensional TMDs. In addition, charge transport analysis of devices based on low dimensional TMDs is a prerequisite for their application. In this PhD Thesis, bottom-up and top-down approaches were used to prepare two-dimensional MoS2 flakes. The electrical properties of thin film transistors based on those 2d materials are investigated. Furthermore, MoO3 nanobelts were synthesized through thermal evaporation and transistors based on those nanobelts were fabricated to understand the transport mechanism of transition metal oxide layered materials
Input and particle-reactivity of transition metals from subgroups IV, V and VI in the water column of the Atlantic Ocean
No full textThis PhD-study focuses on the distribution of the 9 different metals titanium (Ti), zirconium (Zr), hafnium (Hf), vanadium (V), niobium (Nb), tantalum (Ta), vanadium (V), molybdenum (Mo), and tungsten (W) from subgroups IV, V, and VI of the periodic table of elements in seawater.
Within this work an online-preconcentration method has been developed using the SeaFAST-system for Ti, Zr, Hf, Nb, Ta, W. The developed methods have been applied to 194 seawater samples (16 stations) located in the (sub)tropical Atlantic (GEOTRACES research cruise M81/1).
Results on dissolved Zr and Nb concentrations reveal deviations from the typical depth patterns of a particle-reactive metal. The concentration of Zr increased with depth, whereas the distribution of Nb was predominantly conservative except off West Africa. A sequential filtration approach showed that dissolved Zr is present in the size fraction < 0.015 µm and hence organic ligands may complex and stabilize Zr in the dissolved phase leading to the observed increase with depth.
Depth profiles of Mo and W reveal deviations from the commonly assumed conservative depth distribution. In the area influenced by Saharan dust deposition, Mo and W seem to sorb onto deposited mineral particles whereas dust seems to be source for V. Riverine particulate matter seem to release V and Mo in the Amazon estuary while mixing effects with freshwater might explain the observed higher W concentrations in this area.
As a base for future studies on Cr as a paleoproxy for ancient seawater Cr speciation under varying oxygen conditions has been investigated in the Pacific Ocean (research cruise GP13) and in the Atlantic Ocean (M81/1) applying a voltammetric method. Dissolved oxygen did not significantly affect the distribution of Cr redox species in both investigated areas. Cr(III) consisted almost quantitatively of Cr(III_unreactive) in the South Pacific and the Atlantic samples and hence photoreduction processes and organic complexation seem t
Connecting the heat and electricity market for renewable energy integration: Feasibility study and economic efficiency analysis for power to heat
No full textRenewable capacity growth is substantial around the world. A key issue is to find reasonable use for excess fluctuating renewable electricity generation. The idea is to equip conventional options to produce heat with appliances for heat production with electricity. This holds great promise for addressing the vexing challenge of matching an increasing share of electricity supply from fluctuating renewable energy sources with an inelastic electricity demand. The objective is to find out whether there is an intrinsic micro-economic benefit for consumers and producers to shift electricity consumption for heating purposes in dependency of the momentary requirements and market signals. Simulations are made for residential and district heating as well for process steam demand of a paper and a chemical company.
The initial results of the thesis are that it is technically feasible to produce heat with electricity in the investigated sectors and that the heat market can be yielded for excess supply from renewable energy. The trans-sectoral economic comparison shows that in all application fields the levelized cost of heat are competitive with the conventional heat production cost. However, these results are restricted to the exclusion of state-induced price components. Subsequent analyses of the thesis depict that flexible demand interacts with the electricity market. With focus on macro-economic criteria, distinctive advantages emerge from the connection of the heat and electricity market: (1) Heat production with electricity increases the use of renewable electricity generation. (2) It leads to higher short-term electricity prices. (3) It holds substantial potential for reducing final energy demand and emissions from fossil energy sources. Policy-relevant conclusion is that matching flexible demand with a fixed structure of state-induced components is not adequate. Regulatory intervention is advised to establish a time-variable tax structure
Organocatalyzed Reactions for Breaking Symmetry and Reduced Protecting Group Drug Synthesis
No full textThe first part of my Ph.D. work focused on an ignored reaction, the enantioselective mono-aldolization of diketones. 4-substituted cyclohexanone based diketones were synthesized and it was convincingly shown that the regio-, diastereo- and enantiocontrol could be imparted at the cyclohexanone ketone carbonyl unit while acyclic methyl, aromatic, or benzyl ketones remained unreacted. The mono-aldol products were then converted into diastereomerically pure keto-1,3-diols or keto-lactones with excellent enantioselectivity ee. These advanced building blocks then allowed a variety of Alzheimer -secretase inhibitor drug targets to formally be accessed. Beyond those fundamental achievements, but within the same project, I was able to show a catalyst based achievement, the first useful access to previously inaccessible diastereomeric aldol products.
The last third of my research focused on the use of primary amine catalysts, amino acid based, for the first extensive broadening of the Michael substrate scope since its broader introduction decades ago. Here I was able to show that acidic functional groups, e.g., phenolic OH, amide NH, and carboxylic acid moieties are fully tolerated under catalytic enantioselective conditions. This is important because it shows that protecting groups can be avoided and this lead to the shortest and highest yielding route to (R)-Pristiq, (-)-O-desmethylvenlafaxine, a commercially prescribed antidepressant
Collaborative Recovery from Supply Chain Disruptions
No full textToday’s supply chains are increasingly global and interconnected while aiming at the same time to lower inventory levels and shorten lead times. This combination makes supply chains more vulnerable to disruptions. In addition, both the number and the severity of supply chain disruptions are increasing. Recovering from supply chain disruptions represents a major challenge for supply chain professionals. There is a lack of research on collaborative networks and their abilities to combine resources after a disruption occurred. Overall, there is a need for a reactive risk management method which meets the framework conditions and addresses the research gaps. By collaborating during disruption recoveries, i.e. leveraging the resources available in their networks, supply chains can recover from disruptions quicker than competing supply chains.
This research aims at analysing the relation between collaborative resource sharing and supply chain resilience. It builds on the relational view as a theoretical foundation. Based on extensive literature review, multiple case studies and expert interviews, a framework of collaborative recovery is developed. It incorporates promoting factors, types and effects of collaborative resource sharing. To test the framework, structural equation modeling is conducted with 216 data sets from a survey.
The study shows that the sharing of both human resources and production resources during disruption recoveries has a positive effect on supply chain resilience. Supply chains recover faster than competing supply chains and gain a collaborative advantage. Trust and commitment are identified as main promoting factors of collaborative resource sharing. Dependency indirectly influences collaborative resource sharing through trust and commitment. These empirical findings have implications for supply chain and risk managers. In addition, advancements in the relational view theory are made
Sustainable Business at the Base of the Pyramid: An Empirical Investigation
No full textSustainable development issues have been at the forefront of public policy, academic debate, private sector decision making and civil society opinion in the past decade. In order to address aspects related to climate change, global poverty and inclusive economic growth, collaboration between various stakeholders from different sectors and geographical regions is needed. There is increasing pressure coming from governments and civil society on firms of all sizes to incorporate social and ecological aspects into their business activities. Current literature has explored issues of sustainability mainly in the context of industrialized countries and with a strong focus on ecological aspects. Yet, literature has scarcely addressed issues of sustainable business efforts in the context of poverty which presents unique challenges and critical interactions between economic, social and ecological issues.
This thesis investigates sustainable business concerns in the context of low-income markets, also known as Base of the Pyramid. The aim of this research is to understand how to enhance sustainable performance of business efforts for inclusive and environmentally friendly economic growth from the perspective of micro, small and medium sized enterprises operating in Base of the Pyramid markets. In order to achieve this aim, drivers, approaches, mechanisms and interdependencies of sustainable performance are investigated.The research process begins with a review of existing literature and a multiple case study analysis in order to develop a theoretical framework with drivers, mechanisms and interdependencies of sustainable performance. Hypotheses proposed by the theoretical framework are tested via a large scale empirical study. In a final step, a typology of enterprises operating in Base of the Pyramid markets is proposed to guide the development of practical recommendations
TolC imaging and its time-resolved production dynamics
No full textTolC is a component of the protein complex that forms the main bacterial efflux system involved in expelling out of the cell numerous harmful antibacterial chemicals such as antibiotics and detergents. TolC is the outer membrane component of the system and it connects with an inner membrane energy-demanding pump, which can be either an ABC transporter or a proton antiporter. A periplasmic membrane fusion protein seals the connection of the two. TolC is able to bind a multitude of such transporters which have very different substrate specificities thus TolC part-taking in the efflux of dozens of substrates. This makes TolC be a main participant in the phenomenon of multidrug efflux and a better understanding of its behavior in vivo is thus required. In the present study, the spatial localization and time-resolved dynamics of TolC production in live cells is described. This is achieved by labeling the TolC protein genomically with an oxidation-resistant variant of GFP, superfolder GFP. The labelled protein is fully functional and shows a growth medium-dependent expression. Furthermore, certain antibiotics increase its production in a concentration-dependent manner. This is the first time such a behavior was shown and opens new ways for further research
Models of Biological Regulation
No full textMetabolism is thought to be robust against multiple types of
perturbations since organisms have survived millions of years of selective evolution. Some of the challenges handled by metabolic systems are the transport,
transformation and storage of compounds. All biochemical processes in a cell
have to occur at physiological conditions, maintain energy levels and tolerate
fluctuating environmental conditions. The organization and regulation of these
processes is thus of great interest to the field of logistics where solutions to the
dynamic control of complex systems are desperately needed.
As a basis, the metabolism and transcriptional regulatory
network of Escherichia coli, a thoroughly studied experimental model
organism, are compared with company networks gleaned from actual production
data.
A number of results are established: (i) A direct relation between the
unit components of the metabolic and logistics systems. This involves the
biochemical reactions and manufacturing steps involved with the material flow
on the networks, as well as a concept for the regulatory elements. (ii) Potentially
beneficial structural elements of metabolic networks are discussed and the
composition of few-node subgraphs as one such indicator is explored in E.
coli’s metabolic network. (iii) The structure of networks tasked with specific
patterns of flow distribution and robust to particular types of local damages are
investigated. A clear relation between shared sub-patterns and the occurrence of
modular structures is observed. (iv) The large-scale organization of regulation
in wild type E. coli and two mutants is confirmed to be dominated by the
two counterbalancing aspects of digital (transcriptional) and analog (physico-
chemical) control over the course of E. coli’s growth cycle. (v) A case is made
for the recording of results as a function of the increasing amount of knowledge
available about objects of study