Now showing items 1-10 of 19
A scenario approach to modeling land-use changes and assessing associated environmental impacts in Southern Amazonia
Humanity has left its footprint on the surface of the earth since it managed to purposefully employ tools and fire to its specific needs. Especially the conversion of natural habitats into agricultural productive land has transformed close to forty percent of the natural land-cover in order to satisfy global demands for food, raw materials, and energy. One current example of dynamic land-use and land-cover changes can be witnessed in Southern Amazonia. Spatially explicit land-use change models are applied to investigate ...
Self-Healing in Autonomous Robot Teams
Today, robots are used in nearly every type of automated manufacturing and assembly process. Robot installations typically apply static actuator systems in clearly structured environments. These systems show impressive abilities in speed and accuracy for repetitive manipulation tasks. Future automation applications, however, require an increasing level of flexibility, where classical systems reach their physical limits. As a reaction, robots become mobile, intelligent and cooperative. These new characteristics, ...
Supporting Researchers: Analyzing the Scholarly Publication Life Cycle and Social Bookmarking Systems
Researchers must face the exponential growth of the body of available scholarly literature, which makes it ever harder to keep track with one’s own community, especially for newcomers. In this thesis, we explore different means of supporting researchers with that task. For this purpose, we follow two approaches: We provide analyses of research communities and of researchers’ interactions through data that can be obtained from the phases in the life cycle of scholarly publications (creation, dissemination, usage, and ...
Software Stories Guide
Software Stories are a simple graphical notation for requirements analysis and design in agile software projects. Software Stories are based on example scenarios. Example scenarios facilitate the communication between lay people or domain experts and software experts.
Transfer characteristics of white light interferometers and confocal microscopes
Optical profilers present significant advantages in comparison with stylus profilometry and scanning probe microscopy due to their non-contacting technique and their ability to scan the entire measurement field simultaneously. However, optical profilers suffer from different systematical artifacts. The dissertation investigates the transfer characteristics of optical profilometers, namely white light interferometers and confocal microscopes. In white light interferometry dispersion in the optical system leads to ...
Development, Evaluation and Optimization of Fabrication Processes for Daylight Guiding Systems Based on Micromirror Arrays
In this work, fabrication processes for daylight guiding systems based on micromirror arrays are developed, evaluated and optimized.Two different approaches are used: At first, nanoimprint lithography is used to fabricate large area micromirrors by means of Substrate Conformal Imprint Lithography (SCIL).Secondly,a new lithography technique is developed using a novel bi-layered photomask to fabricate large area micromirror arrays. The experimental results showing a reproducible stable process, high yield, and is ...
Optical Sensor Array based Nanospectrometer: Fabrication of high resolution 3D NanoImprint master templates and bonding of Fabry-Pérot filter array onto photodetector array
In the field of optical spectroscopy, spectrometers are high resolution optical sensors that have emerged as a platform for a wide range of application fields. Commercially available spectrometers are bulky and expensive. Hence, this limits its integration into modern mobile and wearable devices. To overcome this limitation, miniaturization of spectrometers is an interesting target for a wide range of emerging applications. The most attractive concept of fabricating miniaturized spectrometers is the Fabry-Pérot filter ...
Design and Numerical Simulation of Dielectric Photonic Crystal Devices and Investigation of an Optical Characterization Method
In this research work, dielectric photonic crystal (PhC) structures based on low refractive index slab waveguide are investigated. These two-dimensional slab waveguide PhC structures work on the principle of guided-mode resonance and find their application in optical filters operated in the near-infrared range. The design and numerical simulation of the presented PhCs are carried out using finite-difference time-domain (FDTD) method. The dielectric materials used in the presented structures are zirconium dioxide/niobium ...
Residual-Layer-Free 3D Nanoimprinting using Novel Hybrid Soft Templates
Hybrid 3D soft templates are designed and evaluated for residual layer free 3D imprinting in UV-Substrate Conformal Imprint Lithography (SCIL). 3D imprinting usually results in laterally varying residual layers, which cannot be removed by conventional etching processes in a satisfactory manner. The hybrid templates introduced in this thesis are hybrid in a way that their template protrusions are enclosed with a UV-blocking metal layer, by this means selective UV curing of the resist material is attainable. Hence, the ...
Load Reducing Control for Wind Turbines: Load Estimation and Higher Level Controller Tuning based on Disturbance Spectra and Linear Models
The aim of this work is to demonstrate an efficient and pragmatic approach for design and optimization of load reducing controllers for wind turbines. Load reducing control means that, besides the classical rotor speed control loop, load or oscillation signals are included as additional input signals into the controller. Thereby, a multiple-input-multiple-output (MIMO) control design problem arises. While the basic concepts of load reducing control and the achievable load reductions are essentially known from ...