A Probabilistic Approach for Spatio-Temporal Phase Unwrapping in Multi-Frequency Phase-Shift Coding

Multi-frequency techniques with temporally encoded pattern sequences are used in phase-measuring methods of 3D optical metrology to suppress phase noise but lead to ambiguities that can only be resolved by phase unwrapping. However, classical phase unwrapping methods do not use all the information to unwrap all measurements simultaneously and do not consider the periodicity of the phase, which can lead to errors. We present an approach that optimally reconstructs the phase on a pixel-by-pixel basis using a probabilistic modeling approach. The individual phase measurements are modeled using circular probability densities. Maximizing the compound density of all measurements yields the optimal decoding. Since the entire information of all phase measurements is simultaneously used and the wrapping of the phases is implicitly compensated, the reliability can be greatly increased. In addition, a spatio-temporal phase unwrapping is introduced by a probabilistic modeling of the local pixel neighborhoods. This leads to even higher robustness against noise than the conventional methods and thus to better measurement results

Engineering failure analysis and design optimisation with HiP-HOPS

The scale and complexity of computer-based safety critical systems, like those used in the transport and manufacturing industries, pose significant challenges for failure analysis. Over the last decade, research has focused on automating this task. In one approach, predictive models of system failure are constructed from the topology of the system and local component failure models using a process of composition. An alternative approach employs model-checking of state automata to study the effects of failure and verify system safety properties. In this paper, we discuss these two approaches to failure analysis. We then focus on Hierarchically Performed Hazard Origin & Propagation Studies (HiP-HOPS) - one of the more advanced compositional approaches - and discuss its capabilities for automatic synthesis of fault trees, combinatorial Failure Modes and Effects Analyses, and reliability versus cost optimisation of systems via application of automatic model transformations. We summarise these contributions and demonstrate the application of HiP-HOPS on a simplified fuel oil system for a ship engine. In light of this example, we discuss strengths and limitations of the method in relation to other state-of-the-art techniques. In particular, because HiP-HOPS is deductive in nature, relating system failures back to their causes, it is less prone to combinatorial explosion and can more readily be iterated. For this reason, it enables exhaustive assessment of combinations of failures and design optimisation using computationally expensive meta-heuristics. (C) 2010 Elsevier Ltd. All rights reserved

The deep Critical Zone as a source of mineral nutrients to montane, temperate forest ecosystems

Forest ecosystems persist over thousands of years. The prevailing paradigm describes how a tight nutrient re-utilisation loop (recycling) from organic matter stored in the forest floor into trees ensures forest ecosystem nutrition. However, these nutrients are constantly lost by drainage during storage on the forest floor. This nutrient loss must be balanced on the long-term, because otherwise ecosystems would run into a deficit of mineral nutrients. In supply-limited weathering regimes, which are often found in non-eroding, well-drained settings, chemical weathering has run to completion and the nutrient loss from the forest floor is counterbalanced by external atmospheric wet and dry deposition. In kinetically limited weathering regimes, which are often found in eroding, temperate settings, the regolith (comprising soil, saprolite and weathered rock) still contains mineral nutrients, as mineral dissolution kinetics are slower than the advection of minerals from deep, unweathered rock to the Earth’s surface. At the surface, minerals and plant litter are removed by erosion. The mechanisms by which forest ecosystem nutrition is maintained in the face of these losses is the topic of this thesis. I explore the role of the deeper regolith and the mechanisms and fluxes by which this deep reservoir serves to sustain ecosystems over the long-term. I use geochemical mass balances and innovative metal isotope proxies to derive fluxes and sources from rock weathering into forest trees in montane, eroding and temperate forest ecosystems. How montane, temperate forest ecosystems are nourished was explored at two study sites in the Schwarzwald (site CON) and the Bayerischer Wald (site MIT). Both sites are underlain by paragneiss of contrasting mineralogy, mantled by Cambisols developed on periglacial slope deposits and covered by Fagus sylvatica and Picea abies. At both sites I quantified nutrient availability, nutrient accessibility, fluxes of nutrient supply by chemical weathering, and nutrient uptake by forest trees. The regolith at site CON experienced substantially more nutrient loss through chemical weathering than at site MIT. Nevertheless, nutrient uptake fluxes from forest trees are virtually identical at both sites. Considering a forest ecosystem in a mass balance comprising a shallow `organic nutrient cycle´ and a belowground `geogenic nutrient pathway´ shows that the nutrient inventory in the forest floor is of finite size that lasts only for decades, because persistent nutrient loss through plant litter drainage and erosion occurs from the forest floor. This permanent nutrient loss is balanced by fluxes from a reservoir consisting of the biologically available fraction (water-soluble and easily exchangeable fractions for the metal elements, and exchangeable and calcium-bound phosphorus fractions for phosphorus) from the upper regolith (3 m). This reservoir of nutrients ensures forest ecosystem nutrition over millennia, because it can replace the nutrient loss from the forest floor and is continually replenished through chemical weathering. Supply from this deep reservoir is linked to the organic nutrient cycle which is regulated by uptake into forest trees through the adjustment of the number of nutrient re-utilisation cycles from plant litter depending on nutrient supply fluxes. Thus, uniform uptake of mineral nutrients emerges despite large differences in their release through rock weathering. With this new concept in mind I constrained the uptake depth of the most plant-essential mineral nutrient phosphorus (P). While biologically accessible P forms, namely exchangeable P, are negligible throughout the regolith, the Ca-bound P, biologically available as 〖"PO" 〗_"4" ^"3-" through mineral dissolution, increases with depth and dominates in the lower part of the regolith and in unweathered rock. To test whether this deep P and other mineral nutrients from this depth are utilised by trees, I applied isotopic tracing methods. To track the depth of nutrient uptake radiogenic Strontium (Sr), namely the ^"87"Sr/^"86"Sr ratio, an established isotope proxy for source tracing was used together with the first application of the meteoric cosmogenic Beryllium (Be) isotope system, namely ^"10"Be_"meteoric"/^"9"Be_"stable". From the agreement in these isotope ratios between plant tissue and the forest floor´s biologically accessible fraction I demonstrate that these elements, and by inference also P and other mineral nutrients, are turned over between the forest floor and trees. I also show that these elements initially originate from the lower part of the regolith. Because this depth lies beyond reported rooting depths of the prevalent tree species it is speculated that nutrient uplift occurs through a combination of root-mycorrhiza symbiosis, dimorphic root systems and capillary rise of pore water. Nutrient export after rock weathering was explored in the montane, temperate forest ecosystems of the Southern Sierra Critical Zone Observatory, California, underlain by granodiorite bedrock, mantled by Entisols and Inceptisols and covered mainly by Pinus ponderosa. Magnesium (Mg) stable isotopes are sensitive indicators of Mg utilisation by biota. Mg utilisation takes place from up to 6 m depth, as evidenced by the light Mg isotopic composition of the easily exchangeable fraction. It was further found that trees, in particular wood, are isotopically heavy, whereas stream water is isotopically light. Converting this difference into a mass balance shows that 50-100 % of the Mg released by chemical weathering is utilised by trees. From the comparison between the river dissolved fluxes of other plant-essential and plant-beneficial elements (K, Ca, P and Si) with their weathering release fluxes a deficit is found in the river dissolved fluxes that is attributed to nutrient uptake by forest trees. Thus, either the mineral nutrients are accumulating today in re-growing forest biomass after clear cutting, or they are exported in plant litter and coarse woody debris, rather than appearing in drainage. The two major outcomes of this thesis are that the permanent nutrient loss at the Earth surface by plant litter drainage and erosion is balanced by nutrient uptake from the deep regolith, and that erosion and weathering are coupled through nutrient uptake at depth and erosion of these nutrients in plant debris at the surface

Intrusion of Profession. Participatory Research in Mental Health Day Care

Mit der Transformation der Psychiatrie zur gemeindenahen, dezentralisierten Versorgung sollte es gelingen die Patient_innen in ein institutionelles Netz einzuhegen, welches es ihnen erlaubt, sich in den beruflichen wie sozialen Alltag einzugliedern. Der – nicht zuletzt ökonomisch motivierte – Anspruch, Drehtürpatient_innen zu vermeiden, welche die Kapazitäten der verwahrenden Anstalt belasteten, führte zu einer Diversifizierung des Angebots: Betreute Wohneinrichtungen, Tageskliniken mit ambulanter Versorgung, Werk- und Tagesstätte etablierten sich als Komplemente der stationären Behandlung. Das Erkenntnisinteresse des vorliegenden Artikels richtet sich auf den Alltag in diesen sozialpsychiatrischen Einrichtungen. Entlang einer ethnographischen Untersuchung wird nach der Bedeutung von Arbeit und Sozialbeziehungen innerhalb einer sozialpsychiatrischen Tagesstätte gefragt, wobei zweierlei Aporien betreffend dieser Teilaspekte diskutiert werden: Zum einen reibt sich das Arbeitsverständnis der in der Tagesstätte an einem gesellschaftlichen Arbeitsbegriff, welcher die Reproduktions- von der Produktionssphäre abzuspalten trachtet, und zum anderen kollidiert die von der Sogkraft des geteilten Alltags hergestellte Nähe von Klient_innen und Mitarbeiter_innen mit einer Anrufung zur Professionalität, welches in die Sozialbeziehungen einfällt.Given the transformation of the psychiatric system towards a community-based, decentralized care, it’s objective is to entangle patients in an institutional network, hereby allowing them to (re‑)built a social and everyday professional life. The claim to avoid »revolving door patients« [who/that are] stressing the institutions’ capacities – not least motivated by economic reasons – led to a diversification of supply: assisted living facilities, (ambulatory) day clinics and educational workshops became an integral part of in-patient treatments. In this article, my interest focuses on everyday life at these social-psychiatric facilities. Based on ethnographic studies, questions regarding the meaning of work and social relations within a social-psychiatric day clinic will be risen. Two aporias open up in this context and will be discussed primarily: First of all, the understanding of work within the day clinic differs from society-wide understandings attempting to split up productional and reproductional spheres. Secondly, (emotional) closeness between clients and employees caused by shared everyday experiences collides with the ideal of professionalism which happens to intrude into their social relations

Temporale Phasenentfaltung mittels zirkulärer Statistik und lokalen Nachbarschaftsinformationen

Multi-Frequenz-Verfahren mit temporal codierten Mustersequenzen werden bei phasenmessenden Verfahren der optischen 3D-Messtechnik eingesetzt, um Phasenrauschen zu unterdrücken, führen aber zu Mehrdeutigkeiten, die erst durch eine Phasenentfaltung aufgelöst werden können. Klassische Verfahren nutzen jedoch nicht die gesamte Information, um alle Messungen gleichzeitig zu entfalten, und beachten nicht die Periodizität der Phase, was zu Fehlern führen kann. Wir stellen einen Ansatz vor, bei dem die Phase pixelweise mithilfe einer probabilistischen Modellierung optimal rekonstruiert wird. Die individuellen Messungen werden mithilfe zirkulärer Wahrscheinlichkeitsdichten modelliert. Maximieren der Verbunddichte aller Messungen liefert die optimale Decodierung. Da hierbei die gesamte Information aller Phasenmessungen gleichzeitig verwendet wird und implizit die Faltung der Phase kompensiert wird, kann die Zuverlässigkeit stark erhöht werden. Zusätzlich kann durch modellieren der lokalen Pixel-Nachbarschaften die Phasenentfaltung noch weiter verbessert werden. Dies führt zu einer höheren Robustheit gegenüber Rauschen als die herkömmlichen Verfahren und damit zu besseren Messergebnissen

A simulation framework for the design and evaluation of computational cameras

In the emerging field of computational imaging, rapid prototyping of new camera concepts becomes increasingly difficult since the signal processing is intertwined with the physical design of a camera. As novel computational cameras capture information other than the traditional two-dimensional information, ground truth data, which can be used to thoroughly benchmark a new system design, is also hard to acquire. We propose to bridge this gap by using simulation. In this article, we present a raytracing framework tailored for the design and evaluation of computational imaging systems. We show that, depending on the application, the image formation on a sensor and phenomena like image noise have to be simulated accurately in order to achieve meaningful results while other aspects, such as photorealistic scene modeling, can be omitted. Therefore, we focus on accurately simulating the mandatory components of computational cameras, namely apertures, lenses, spectral filters and sensors. Besides the simulation of the imaging process, the framework is capable of generating various ground truth data, which can be used to evaluate and optimize the performance of a particular imaging system. Due to its modularity, it is easy to further extend the framework to the needs of other fields of application. We make the source code of our simulation framework publicly available and encourage other researchers to use it to design and evaluate their own camera designs