Tomographic Reconstruction of 2-D Atmospheric Trace Gas Distributions from Active DOAS Measurements

Applying the tomographic principle to active DOAS remote sensing leads to a novel technique for the measurement of atmospheric trace gas distributions. Standard analytical methods for the reconstruction of a scalar field from its line integrals cannot be used due to low numbers of light paths (10-50) and their irregular arrangement, so that the concentration field is expanded into a limited number of local (piecewise constant or linear) basis functions instead. The resulting discrete linear inverse problem is solved by a least squares-minimum norm principle. For sharp 2-D concentration peaks it is shown systematically with respect to their extension how the optimal choice of parametrisation (in terms of number and kind of basis functions) and a priori can tremendously improve the reconstruction. Regularisation plays a minor role. Proposals for retrieving peak distributions by combining different parametrisations are again examined systematically showing that their usefulness heavily depends on the features one is most interested in. Comparison of different 2-D light path geometries reveals that linear independency within the associated systems is pivotal. A detailed analysis of the reconstruction error points out special issues of tomography with only few integration paths and argues that a complete error estimation is not possible without a priori assumptions. Based on this discussion a numerical scheme for calculating the reconstruction error is suggested. The findings are applied to an indoor experiment simulating narrow emission puffs and 2-D model distributions above a street canyon, respectively. For the latter case it is demonstrated how model evaluation can be possible even with a relatively small number of light paths. Contrary to the reconstruction of peak distributions regularisation becomes crucial

Polymer-embedded magnetic carbon-coated nanoparticles as versatile catalyst supports

In this work, two different magnetically recoverable catalytic systems were developed and their synthetic utility was investigated. Both catalysts were supported by magnetic Co/C NPs, which rendered them highly reusable through quick and facile removal from the solution with an external magnet. In the first chapter, a Ru NP-based catalyst for the aromatic hydrogenations was investigated. Three distinct strategies for the immobilization of Ru NPs on magnetic Co/C NPs were compared, and a poly(ethylenimine) (PEI)-based system grafted onto the Co/C NPs proved to be superior in terms of reactivity and reusability. The effects of different PEI polymer variations on the catalytic performance were explored, revealing that materials with a lower nitrogen content (and therefore a smaller polymer coating) were ideal. For the final catalyst, a PEI@Co/C NPs system with only 0.3 wt% N was used and the incorporation of Ru NPs was optimized so that up to 67% of the employed Ru were immobilized, giving rise to a high Ru loading of 10.6 wt%. The catalytic activity was evaluated in the hydrogenation of toluene as a model reaction and a TOF of 1,402 h-1 was achieved using 30 bar H2 pressure at room temperature. Reusability of the catalyst was also examined in this reaction, and the catalyst could be recovered and reused for at least 16 consecutive runs with only a minor loss in reactivity and an almost negligible amount of metal leaching with an average of 1.1 ppm/cycle for Ru and 0.1 ppm/cycle for Co. Lastly, the substrate scope of the newly developed catalyst was studied. In total the aromatic hydrogenation of 13 different substrates was shown, including electron-rich and electron-poor systems as well as highly substitutes substrates such as thymol, which gives rise to the highly desired menthol isomers. In the second chapter, a new method for the immobilization of BINOL-based chiral phosphoric acids (CPAs) onto the magnetic Co/C NPs was invented. Employing a procedure developed by Tan et al. for grafting of microporous organic polymers from simple arenes, the aromatic moieties of the CPAs were polymerized using formaldehyde dimethyl acetal (FDA) as an external crosslinker. Since the substituents in the 3,3’- positions of the BINOL play a critical role for the chiral induction of the catalyst, the immobilization was tested for several different CPAs. While CPAs with sterically unhindered aromatic substituents such as a naphthyl moiety were immobilized quantitatively without issues, a copolymerization strategy with benzene had to be employed for CPAs with sterically hindered substituents to achieve the same goal. The resulting catalysts were tested in a number of Brønsted acid-catalyzed reactions with the most success being found in the enantioselective transfer hydrogenation of 2-substituted quinolines. Using the immobilized TRIPS catalyst resulted in the highest selectivity of 85% ee for the model substrate 2-phenyquinoline. Other quinolines with aromatic substituents were also well tolerated reaching selectivities of up to 92% ee for 4-nitrophenyl-quinoline. The recycling capabilities of the system were also explored for the model substrate and the catalyst could be reused for 17 consecutive runs with only negligible losses in reactivity and constantly high ee values of around 80%. Due to this excellent reusability, a total of 1.7 g product could be synthesized with only 25 mg of catalyst material

Sampling-Based Trajectory (re)planning for Differentially Flat Systems: Application to a 3D Gantry Crane

In this paper, a sampling-based trajectory planning algorithm for a laboratory-scale 3D gantry crane in an environment with static obstacles and subject to bounds on the velocity and acceleration of the gantry crane system is presented. The focus is on developing a fast motion planning algorithm for differentially flat systems, where intermediate results can be stored and reused for further tasks, such as replanning. The proposed approach is based on the informed optimal rapidly exploring random tree algorithm (informed RRT*), which is utilized to build trajectory trees that are reused for replanning when the start and/or target states change. In contrast to state-of-the-art approaches, the proposed motion planning algorithm incorporates a linear quadratic minimum time (LQTM) local planner. Thus, dynamic properties such as time optimality and the smoothness of the trajectory are directly considered in the proposed algorithm. Moreover, by integrating the branch-and-bound method to perform the pruning process on the trajectory tree, the proposed algorithm can eliminate points in the tree that do not contribute to finding better solutions. This helps to curb memory consumption and reduce the computational complexity during motion (re)planning. Simulation results for a validated mathematical model of a 3D gantry crane show the feasibility of the proposed approach.Comment: Published at IFAC-PapersOnLine (13th IFAC Symposium on Robot Control

Model Predictive Trajectory Optimization With Dynamically Changing Waypoints for Serial Manipulators

Systematically including dynamically changing waypoints as desired discrete actions, for instance, resulting from superordinate task planning, has been challenging for online model predictive trajectory optimization with short planning horizons. This paper presents a novel waypoint model predictive control (wMPC) concept for online replanning tasks. The main idea is to split the planning horizon at the waypoint when it becomes reachable within the current planning horizon and reduce the horizon length towards the waypoints and goal points. This approach keeps the computational load low and provides flexibility in adapting to changing conditions in real time. The presented approach achieves competitive path lengths and trajectory durations compared to (global) offline RRT-type planners in a multi-waypoint scenario. Moreover, the ability of wMPC to dynamically replan tasks online is experimentally demonstrated on a KUKA LBR iiwa 14 R820 robot in a dynamic pick-and-place scenario.Comment: 8 pages, 6 figure

Current Concepts of Hyperinflammation in Chronic Granulomatous Disease

Chronic granulomatous disease (CGD) is the most common inherited disorder of phagocytic functions, caused by genetic defects in the leukocyte nicotinamide dinucleotide phosphate (NADPH) oxidase. Consequently, CGD phagocytes are impaired in destroying phagocytosed microorganisms, rendering the patients susceptible to bacterial and fungal infections. Besides this immunodeficiency, CGD patients suffer from various autoinflammatory symptoms, such as granuloma formation in the skin or urinary tract and Crohn-like colitis. Owing to improved antimicrobial treatment strategies, the majority of CGD patients reaches adulthood, yet the autoinflammatory manifestations become more prominent by lack of causative treatment options. The underlying pathomechanisms driving hyperinflammatory reactions in CGD are poorly understood, but recent studies implicate reduced neutrophil apoptosis and efferocytosis, dysbalanced innate immune receptors, altered T-cell surface redox levels, induction of Th17 cells, the enzyme indolamine-2,3-dioxygenase (IDO), impaired Nrf2 activity, and inflammasome activation. Here we discuss immunological mechanisms of hyperinflammation and their potential therapeutic implications in CGD

Singularity Avoidance with Application to Online Trajectory Optimization for Serial Manipulators

This work proposes a novel singularity avoidance approach for real-time trajectory optimization based on known singular configurations. The focus of this work lies on analyzing kinematically singular configurations for three robots with different kinematic structures, i.e., the Comau Racer 7-1.4, the KUKA LBR iiwa R820, and the Franka Emika Panda, and exploiting these configurations in form of tailored potential functions for singularity avoidance. Monte Carlo simulations of the proposed method and the commonly used manipulability maximization approach are performed for comparison. The numerical results show that the average computing time can be reduced and shorter trajectories in both time and path length are obtained with the proposed approachComment: 8 pages, 2 figures, Accepted for publication at IFAC World Congress 202

Engineering Multimedia-Aware Personalized Ubiquitous Services

Ubiquitous computing focusing on users and tasks instead of devices and singular applications is an attractive vision for the future. Especially the idea of nomadic, mobile users poses new challenges on hardware and software. Mobile devices provide vastly different presentation capabilities and need to integrate into heterogeneous environments. Network bandwidth is far from being constant and services may be available only when online. This paper presents MUNDO, an infrastructure for ubiquitous computing that addresses these challenges. The infrastructure is intended to be non-monolithic with its parts supporting mobile computing using multi-modal user interfaces, mobile data delivery, and ad-hoc communication and networking

The monumental landscape transformation of the Island of Babeldaob (Republic of Palau)

Babeldaob is the largest island of Palau. The landscape of this mostly volcanic island is dominated by monumental earthworks, like terraced hills, crown and moat constructions, and modified ridgelines. The majority of the Palau earthworks were built between 2400 and 1200 BP, making them the oldest examples of monumentality in Oceania according to the current state of research. Despite the degree of landscape transformation on Babeldaob, the monumental aspect of the earthworks, and the fact that oral traditions are of utmost importance in the Palauan society, little information about the construction, the function, and significance of them has been passed down. Notwithstanding several archaeological investigations in the last years, questions about the chronology, genesis, function, and use of the earthworks are still open. Did the terraces serve as settlement areas? Have they been used for horticulture? Did they have a ritual or political significance? Or were they used for defence? Using aerial photogrammetry, we generated 3D-models of 14 earthworks that served as a basis for placing test trenches to investigate the construction methods and function of the monuments. Detailed geoarchaeological, geomorphological, pedological, and sedimentological analysis showed many aspects of building techniques, ancient land use, and the high stability of the earthworks