Propulsive Capability of a Reel-In Tether with Safe Separation Between Payload and Orbiter

This study investigates the use of a massless reel-in tether for propulsion of a payload following deployment from an orbiter. The distance between the payload and orbiter at closest passage is addressed. A literature review revealed several tether concepts, extensive tether research, and numerous mathematical models. However, previous work in the area of reel-in tethers is limited to propulsion feasibility. The reel-in tether is operated following optimum ejection of the payload from the orbiter using a free arc and subsequent full arc. The free arc of zero tether tension provides initial separation. Switching to a full arc of continuously-maximum tension at the optimum time accelerates and propels the payload until the mission is complete. Tether and winch capabilities are assumed to be satisfactory during the arcs. Families of trajectories are examined for a range of mission times and minimum final payload energy. Families for two ejection speeds provide comparison of propulsion capability, tether length, and minimum separation radius. Safe separation is achievable through variation of the mission duration and/or the ejection speed

Teststrategien für Software- und Hardwarekompatibilität in industriellen Steuerungen

Massenanpassung, kleine Losgrößen, hohe Variabilität der Produkttypen und ein sich während des Lebenszyklus einer industriellen Anlage änderndes Produktportfolio sind aktuelle Trends der Industrie. Durch eine zunehmende Entkopplung der Entwicklung von Software- und Hardwarekomponenten im industriellen Kontext, entstehen immer häufiger Kompatibilitätsprobleme innerhalb von industriellen Steuerungen. In dieser Arbeit wird mittels Literaturrecherche und angewandter Forschung ein Strategiekonzept zur Kompatibilitätsprüfung hergeleitet und diskutiert. Dieses vierphasige Konzept ermittelt Inkompatibilitäten zwischen Software- und Hardwarekomponenten im Umfeld von industriellen Steuerungen und ermöglicht Testingenieuren das frühzeitige Erkennen von Problemen. Durch eine automatische Durchführung der Kompatibilitätsprüfung auf einem externen Industrie PC kann die Kompatibilitätsprüfung sowohl beim Aufspielen neuer Software auf die industrielle Steuerung als auch beim Neustart der Steuerung ablaufen. Somit werden Änderungen an den Komponenten stetig erkannt und Inkompatibilitäten vermieden. Weiterhin kann durch die frühzeitige Erkennung sichergestellt werden, dass eine Anlage dauerhaft lauffähig bleibt. Anhand einer Diskussion werden Mittel festgestellt, um die Robustheit und Anwendbarkeit des vorgestellten Konzeptes zusätzlich zu festigen.:1 Motivation 1 1.1 Aufgabenanalyse 3 1.1.1 Forschungsfragen und Teilaufgaben 3 1.1.2 Aufgabenkomplexe 4 1.1.3 Eingrenzung der Aufgabenstellung 5 1.1.4 Ziel der Arbeit 6 1.1.5 Festsetzung von Formulierungen 6 2 Einführung und Stand der Technik 7 2.1 VIBN von industriellen Anlagen 7 2.1.1 Teststrategien aus der VIBN 9 2.1.1.1 Model-in-the-Loop 9 2.1.1.2 Software-in-the-Loop 9 2.1.1.3 Hardware-in-the-Loop 10 2.1.1.4 Konklusion und Forschungsbestrebungen 11 2.2 CS in industriellen Anlagen 12 2.2.1 Sicherheitsziel 13 2.2.2 Teststrategien aus der CS 13 2.2.2.1 Signaturbasierte Erkennung 14 2.2.2.2 Anomaliebasierte Erkennung 14 2.2.2.3 Konklusion und Forschungsbestrebungen 16 2.3 Interoperabilität als Kompatibilitätsmaß 16 2.4 Testautomatisierung und Test Case Generierung 17 2.5 Allgemeine Softwareteststrategien 17 2.5.1 Modellbasiertes Testen 17 2.5.2 Funktionale Tests 18 2.6 Allgemeine Hardware Teststrategien 19 2.6.1 Modellbasiertes Testen 19 2.6.2 Manuelles Testen 19 2.7 Interoperabilität in industriellen Anlagen 20 2.7.1 Definitionen der Interoperabilität 20 2.7.2 Herausforderungen der Interoperabilität 22 2.7.3 Implementierung von Interoperabilität 22 2.7.3.1 Syntaktische Interoperabilität 23 2.7.3.2 Semantische Interoperabilität 23 2.7.4 Vertikale Integration 24 2.7.5 Horizontale Integration 25 3 Anforderungsanalyse 27 3.1 Adaption von Strategien der VIBN und CS 27 3.2 Anforderungen 28 3.2.1 Anforderungen an die Kompatibilitätsprüfung 28 3.2.2 Anforderungen an die Hardwarekomponenten 29 3.2.3 Anforderungen an die Softwarekomponenten 29 4 Konzept 30 4.1 Komponenten des Teststrategiekonzeptes 30 4.1.1 SPS Selbsttest 32 4.1.2 Export & Import des Soll-Zustandes 32 4.1.3 Ermittlung des Ist-Zustandes 35 4.1.4 Vergleich des Soll- & Ist-Zustandes 35 4.2 Fehlerdetektionstabellen 36 4.3 Reaktionen auf Inkompatibilitäten 38 5 Evaluation 39 5.1 Methodik und Evaluationskriterien 39 5.2 Anwendungsbeispiel 39 5.3 Referenzsystem für Evaluation 41 5.4 Durchführung Evaluation 41 5.5 Erfüllung der Anforderungen an die Kompatibilitätsprüfung 46 6 Diskussion 48 6.1 Beantwortung der Forschungsfragen 48 6.2 Diskussion zur Forschungsmethodik 48 6.3 Bewertung des Konzeptes 49 7 Zusammenfassung und Ausblick 50 7.1 Zusammenfassung 50 7.2 Ausblick und weitere Forschungsarbeit 51 Literaturverzeichnis 52Mass customization, small batch sizes, high variability of product types and a changing product portfolio during the life cycle of an industrial plant are current trends in the industry. Due to an increasing decoupling of the development of software and hardware components in an industrial context, compatibility problems within industrial control systems arise more and more frequently. In this thesis, a strategy concept for compatibility testing is derived and discussed by means of literature review and applied research. This 4-phased strategy concept identifies incompatibilities between software and hardware components in the industrial control environment and enables test engineers to detect problems at an early stage. By automating the compatibility test on an external I-PC, the test can be run both when new software is installed on the industrial controller and when the controller is restarted. Thus, changes to the components are constantly detected and incompatibilities are avoided. Furthermore, early incompatibility detection can ensure that a system remains permanently operational. Based on a discussion, additionally strategies are identified to consolidate the robustness and applicability of the presented concept.:1 Motivation 1 1.1 Aufgabenanalyse 3 1.1.1 Forschungsfragen und Teilaufgaben 3 1.1.2 Aufgabenkomplexe 4 1.1.3 Eingrenzung der Aufgabenstellung 5 1.1.4 Ziel der Arbeit 6 1.1.5 Festsetzung von Formulierungen 6 2 Einführung und Stand der Technik 7 2.1 VIBN von industriellen Anlagen 7 2.1.1 Teststrategien aus der VIBN 9 2.1.1.1 Model-in-the-Loop 9 2.1.1.2 Software-in-the-Loop 9 2.1.1.3 Hardware-in-the-Loop 10 2.1.1.4 Konklusion und Forschungsbestrebungen 11 2.2 CS in industriellen Anlagen 12 2.2.1 Sicherheitsziel 13 2.2.2 Teststrategien aus der CS 13 2.2.2.1 Signaturbasierte Erkennung 14 2.2.2.2 Anomaliebasierte Erkennung 14 2.2.2.3 Konklusion und Forschungsbestrebungen 16 2.3 Interoperabilität als Kompatibilitätsmaß 16 2.4 Testautomatisierung und Test Case Generierung 17 2.5 Allgemeine Softwareteststrategien 17 2.5.1 Modellbasiertes Testen 17 2.5.2 Funktionale Tests 18 2.6 Allgemeine Hardware Teststrategien 19 2.6.1 Modellbasiertes Testen 19 2.6.2 Manuelles Testen 19 2.7 Interoperabilität in industriellen Anlagen 20 2.7.1 Definitionen der Interoperabilität 20 2.7.2 Herausforderungen der Interoperabilität 22 2.7.3 Implementierung von Interoperabilität 22 2.7.3.1 Syntaktische Interoperabilität 23 2.7.3.2 Semantische Interoperabilität 23 2.7.4 Vertikale Integration 24 2.7.5 Horizontale Integration 25 3 Anforderungsanalyse 27 3.1 Adaption von Strategien der VIBN und CS 27 3.2 Anforderungen 28 3.2.1 Anforderungen an die Kompatibilitätsprüfung 28 3.2.2 Anforderungen an die Hardwarekomponenten 29 3.2.3 Anforderungen an die Softwarekomponenten 29 4 Konzept 30 4.1 Komponenten des Teststrategiekonzeptes 30 4.1.1 SPS Selbsttest 32 4.1.2 Export & Import des Soll-Zustandes 32 4.1.3 Ermittlung des Ist-Zustandes 35 4.1.4 Vergleich des Soll- & Ist-Zustandes 35 4.2 Fehlerdetektionstabellen 36 4.3 Reaktionen auf Inkompatibilitäten 38 5 Evaluation 39 5.1 Methodik und Evaluationskriterien 39 5.2 Anwendungsbeispiel 39 5.3 Referenzsystem für Evaluation 41 5.4 Durchführung Evaluation 41 5.5 Erfüllung der Anforderungen an die Kompatibilitätsprüfung 46 6 Diskussion 48 6.1 Beantwortung der Forschungsfragen 48 6.2 Diskussion zur Forschungsmethodik 48 6.3 Bewertung des Konzeptes 49 7 Zusammenfassung und Ausblick 50 7.1 Zusammenfassung 50 7.2 Ausblick und weitere Forschungsarbeit 51 Literaturverzeichnis 5

Autecology of Limnomysis benedeni Czerniavsky, 1882 (Crustacea: Mysida) in Lake Constance, Southwestern Germany

AbstractThe Ponto-Caspian mysid Limnomysis benedeni was first recorded in Lake Constance in summer 2006, and a stable population developed at the site of discovery. Although this mysid is common in the Rhine and Danube rivers, little is known about its ecology and impact in systems of invasion. We investigated the autecology of L. benedeni in habitat-choice and food experiments. In the habitat-choice experiments, highly structured habitats, i.e., stones covered with zebra mussels (Dreissena polymorpha), macrophytes, and especially stonewort, were strongly preferred. In food experiments, L. benedeni fed mostly on food sources with a small particle size, e.g., biofilm on leaf litter, biodeposited material of zebra mussels, epilithon, and phytoplankton. We also compared the L. benedeni population data from Lake Constance with that from rivers. In Lake Constance, female L. benedeni were nearly 30% larger and carried more than three times more eggs in spring (9.4±0.6mm and 28.4±5.7 eggs) than in summer (6.7±0.8mm and 8.7±2.9 eggs). The mysids present in spring might be the generation that over-wintered; in summer, this generation was probably replaced by a new generation of smaller individuals. The large brood size and the detritivorous feeding strategy might allow L. benedeni to colonize Lake Constance rapidly

Increased risk of phosphorus limitation at higher temperatures for Daphnia magna

Invertebrate herbivores frequently face growth rate constraints due to their high demands for phosphorus (P) and nitrogen (N). Temperature is a key modulator of growth rate, yet the interaction between temperature and P limitation on somatic growth rate is scarcely known. To investigate this interaction, we conducted a study on the somatic growth rate (SGR) of the cladoceran Daphnia magna, known to be susceptible to P-limitation. We determined the SGR across a broad range of dietary P content of algae (carbon (C):P ratios (125–790), and at different temperatures (10–25°C). There was a strong impact of both temperature and C:P ratio on the SGR of D. magna, and also a significant interaction between both factors was revealed. The negative effect of dietary C:P on growth rate was reduced with decreased temperature. We found no evidence of P limitation at lowest temperature, suggesting that enzyme kinetics or other measures of food quality overrides the demands for P to RNA and protein synthesis at low temperatures. These findings also indicate an increased risk of P limitation and thus reduced growth efficiency at high temperatures

Enrichment of Omnivorous Cercozoan Nanoflagellates from Coastal Baltic Sea Waters

Free-living nano-sized flagellates are important bacterivores in aquatic habitats. However, some slightly larger forms can also be omnivorous, i.e., forage upon both bacterial and eukaryotic resources. This hitherto largely ignored feeding mode may have pronounced implications for the interpretation of experiments about protistan bacterivory. We followed the response of an uncultured group of omnivorous cercozoan nanoflagellates from the Novel Clade 2 (Cerc_BAL02) to experimental food web manipulation in samples from the Gulf of Gdańsk (Southern Baltic Sea). Seawater was either prefiltered through 5 µm filters to exclude larger predators of nanoflagellates (F-treatment), or prefiltered and subsequently 1∶10 diluted with sterile seawater (F+D-treatment) to stimulate the growth of both, flagellates and bacteria. Initially, Cerc_BAL02 were rapidly enriched under both conditions. They foraged on both, eukaryotic prey and bacteria, and were highly competitive at low concentrations of food. However, these omnivores were later only successful in the F+D treatment, where they eventually represented almost one fifth of all aplastidic nanoflagellates. By contrast, their numbers stagnated in the F-treatment, possibly due to top-down control by a concomitant bloom of other, unidentified flagellates. In analogy with observations about the enrichment of opportunistically growing bacteria in comparable experimental setups we suggest that the low numbers of omnivorous Cerc_Bal02 flagellates in waters of the Gulf of Gdańsk might also be related to their vulnerability to grazing pressure

Plankton ecology: The past two decades of progress

This is a selected account of recent developments in plankton ecology. The examples have been chosen for their degree of innovation during the past two decades and for their general ecological importance. They range from plankton autecology over interactions between populations to community ecology. The autecology of plankton is represented by the hydromechanics of plankton (the problem of life in a viscous environment) and by the nutritional ecology of phyto- and zooplankton. Population level studies are represented by competition, herbivory (grazing), and zooplankton responses to predation. Community ecology is represented by the debate about bottom- up vs. top-down control of community organization, by the PEG model of seasonal plankton succession, and by the recent discovery of the microbial food web

Autotrophic and heterotrophic acquisition of carbon and nitrogen by a mixotrophic chrysophyte established through stable isotope analysis

Collectively, phagotrophic algae (mixotrophs) form a functional continuum of nutritional modes between autotrophy and heterotrophy, but the specific physiological benefits of mixotrophic nutrition differ among taxa. Ochromonas spp. are ubiquitous chrysophytes that exhibit high nutritional flexibility, although most species generally fall towards the heterotrophic end of the mixotrophy spectrum. We assessed the sources of carbon and nitrogen in Ochromonas sp. strain BG-1 growing mixotrophically via short-term stable isotope probing. An axenic culture was grown in the presence of either heat-killed bacteria enriched with ^(15)N and ^(13)C, or unlabeled heat-killed bacteria and labeled inorganic substrates (^(13)C-bicarbonate and ^(15)N-ammonium). The alga exhibited high growth rates (up to 2 divisions per day) only until heat-killed bacteria were depleted. NanoSIMS and bulk IRMS isotope analyses revealed that Ochromonas obtained 84–99% of its carbon and 88–95% of its nitrogen from consumed bacteria. The chrysophyte assimilated inorganic ^(13)C-carbon and ^(15)N-nitrogen when bacterial abundances were very low, but autotrophic (photosynthetic) activity was insufficient to support net population growth of the alga. Our use of nanoSIMS represents its first application towards the study of a mixotrophic alga, enabling a better understanding and quantitative assessment of carbon and nutrient acquisition by this species

Rising nutrient-pulse frequency and high UVR strengthen microbial interactions

Solar radiation and nutrient pulses regulate the ecosystem’s functioning. However, little is known about how a greater frequency of pulsed nutrients under high ultraviolet radiation (UVR) levels, as expected in the near future, could alter the responses and interaction between primary producers and decomposers. In this report, we demonstrate through a mesocosm study in lake La Caldera (Spain) that a repeated (press) compared to a one-time (pulse) schedule under UVR prompted higher increases in primary (PP) than in bacterial production (BP) coupled with a replacement of photoautotrophs by mixotrophic nanoflagellates (MNFs). The mechanism underlying these amplified phytoplanktonic responses was a dual control by MNFs on bacteria through the excretion of organic carbon and an increased top-down control by bacterivory. We also show across a 6-year whole-lake study that the changes from photoautotrophs to MNFs were related mainly to the frequency of pulsed nutrients (e.g. desert dust inputs). Our results underscore how an improved understanding of the interaction between chronic and stochastic environmental factors is critical for predicting ongoing changes in ecosystem functioning and its responses to climatically driven changes.This study was supported by the Ministerio de Economía y Competitividad and Fondo Europeo de Desarrollo Regional (FEDER) (CGL2011-23681 and CGL2015-67682-R to PC), Ministerio de Medio Ambiente, Rural, y Marino (PN2009/067 to PC) and Junta de Andalucía (Excelencia projects P09-RNM-5376 and P12-RNM-327 to PC and JMMS, respectively). M.J.C. was supported by the Spanish Government “Formación de Profesorado Universitario” PhD grant (FPU12/01243) and I.D.-G. by the Junta de Andalucía “Personal Investigador en Formación” PhD grant (FPI RNM-5376). This work is in partial fulfillment of the Ph. D. thesis of M.J.C