Global ETD Search

181	Potential effects of climate change and fire management on fire behavior and vegetation patterns on an east Cascades landscape Greaves, Heather E. 17 October 2012 (has links) Climate exerts considerable control on wildfire regimes, and climate and wildfire are both major drivers of forest growth and succession in interior Northwest forests. Estimating potential response of these landscapes to anticipated changes in climate helps researchers and land managers understand and mitigate impacts of climate change on important ecological and economic resources. Spatially explicit, mechanistic computer simulation models are powerful tools that permit researchers to incorporate climate and disturbance events along with vegetation physiology and phenology to explore complex potential effects of climate change over wide spatial and temporal scales. In this thesis, I used the simulation model FireBGCv2 to characterize potential response of fire, vegetation, and landscape dynamics to a range of possible future climate and fire management scenarios. The simulation landscape (~43,000 hectares) is part of Deschutes National Forest, which is located at the interface of maritime and continental climates and is known for its beauty and ecological diversity. Simulation scenarios included all combinations of +0��C, +3��C, and +6��C of warming; +10%, ��0%, and -10% historical precipitation; and 10% and 90% fire suppression, and were run for 500 years. To characterize fire dynamics, I investigated how mean fire frequency, intensity, and fuel loadings changed over time in all scenarios, and how fire and tree mortality interacted over time. To explore vegetation and landscape dynamics, I described the distribution and spatial arrangement of vegetation types and forest successional stages on the landscape, and used a nonmetric multidimensional scaling (NMS) ordination to holistically evaluate overall similarity of composition, structure, and landscape pattern among all simulation scenarios over time. Changes in precipitation had little effect on fire characteristics or vegetation and landscape characteristics, indicating that simulated precipitation changes were not sufficient to significantly affect vegetation moisture stress or fire behavior on this landscape. Current heavy fuel loads controlled early fire dynamics, with high mean fire intensities occurring early in all simulations. Increases in fire frequency accompanied all temperature increases, leading to decreasing fuel loads and fire intensities over time in warming scenarios. With no increase in temperature or in fire frequency, high fire intensities and heavier fuel loads were sustained. Over time, more fire associated with warming or less fire suppression increased the percentage of the landscape occupied by non-forest and fire-sensitive early seral forest successional stages, which tended to increase the percentage of fire area burning at high severity (in terms of tree mortality). This fire-vegetation relationship may reflect a return to a more historical range of conditions on this landscape. Higher temperatures and fire frequency led to significant spatial migration of forest types across the landscape, with communities at the highest and lowest elevations particularly affected. Warming led to an upslope shift of warm mixed conifer and ponderosa pine (Pinus ponderosa) forests, severely contracting (under 3�� of warming) or eliminating (under 6�� of warming) area dominated by mountain hemlock (Tsuga mertensiana) and cool, wet conifer forest in the high western portion of the landscape. In lower elevations, warming and fire together contributed to significant expansion of open (<10% tree canopy cover) forest and grass- and shrubland. The compositional changes and spatial shifts simulated in the warming scenarios suggest that climate change is likely to significantly affect forests on this landscape. Warming and associated fire also tended to increase heterogeneity of forest structural stages and landscape pattern, resulting in a more diverse distribution of structural stages, especially in lower elevations, and a more divided landscape of smaller forest stands. The NMS ordination emphasized the dissimilarity between the severe +6�� scenarios and the other two temperature scenarios. The +0�� and +3�� scenarios differed from each other in composition (mainly because cool forest was lost in the +3�� scenarios), but within a given level of fire suppression they remained remarkably similar in terms of overall composition, structure, and landscape pattern, while the +6�� scenarios separated noticeably from them. Such decisive differences suggest that under the simulated ranges of precipitation and fire suppression, the interval between 3 and 6 degrees of warming on this landscape may capture an ecological threshold, or tipping point. Additional simulation research that incorporates (for example) management actions, insects and pathogens, and a wider array of precipitation scenarios could help illuminate more clearly the possible range of future landscape conditions. Still, these results provide a glimpse of potential divergent outcomes on this important landscape under possible future climates, and suggest that these forests will undergo considerable changes from both historical and current conditions in response to higher temperatures expected in this area. Some changes may be inevitable with warming, such as the upslope shift of warm forest types, but careful planning for fire and fuels management might allow land managers to modulate fire behavior and steer vegetation dynamics toward the most desirable outcome possible. / Graduation date: 2013 Pacific Northwest dry forests fire climate change FireBGCv2 modeling Oregon East Cascades
182	EXPLAINING VARIATION IN AMERICAN LOBSTER (HOMARUS AMERICANUS) AND SNOW CRAB (CHIONOECETES OPILIO) ABUNDANCE IN THE NORTHWEST ATLANTIC OCEAN Boudreau, Stephanie Anne 26 March 2012 (has links) In this thesis I assessed the causes of long-term changes in two large, commercially important decapod crustacean populations, American lobster (Homarus americanus) and snow crab (Chionoecetes opilio), in the northwest (NW) Atlantic Ocean. By combining available time-series data, including commercial landings, research surveys, and local ecological knowledge (LEK), I explored the causes of an observed ecosystem shift in the NW Atlantic (~1950–2009) which entailed a region-wide decline of groundfish and an increase in benthic invertebrates, including these decapods. Three hypotheses were examined to explain the increase in decapod abundance: (1) the predation hypothesis, whereby a decrease in predatory groundfish led to an increase in their decapod prey (top-down effects); (2) the climate hypothesis, whereby changes in temperature or other climatic variables helped to increase decapod numbers (bottom-up effects); and (3) the anthropogenic hypothesis, whereby changes in fishing pressure drove decapod population dynamics. I explored these hypotheses separately for lobster and snow crab, which may experience different ecological and commercial pressures. First, I investigated the interactions between predatory groundfish and lobster in the inshore region of southwest Nova Scotia. Long-term fisheries-independent abundance indices for lobsters and their predators are available for Gulf of Maine (GOM) waters in the USA, but not in Canada. To address research gaps I designed and executed a survey to collect the LEK of lobster fishermen fishing in the Canadian GOM. Forty-two fishermen were interviewed. Corresponding survey results from the USA were compared to the LEK results. Both sources provided evidence for a top-down effect (predation release), contributing to observed increases in GOM lobster abundance and landings. Second, I explored relationships between lobster abundance and landings in the NW Atlantic as they may relate to temporal changes in predators, temperature, climate (North Atlantic Oscillation Index, NAOI), and fishing. Available landings data and fisheries-independent abundance estimates were collated to investigate trends in lobster abundance and catch. Links between lobster, groundfish, temperature and climate indices were explored using mixed effects models. Results offered partial support for the predation hypothesis, namely in the waters off Newfoundland, Nova Scotia, and southern New England as well as broad support for a climate effect on early life stages. This effect appeared related to a region-wide climate signal, the NAOI, but was independent of changes in water temperature. Fishing effort appeared to be following lobster abundance, rather than regulating abundance in a consistent way. Third, variation in snow crab abundance was examined through meta-analysis of time-series data of cod and crab abundance and temperature. Temperature had opposing effects on the two species: snow crab abundance was negatively correlated with temperature whereas cod and temperature were positively related. Controlling for the effect of temperature, the analysis revealed significant negative interactions between snow crab and cod abundance, with cod leading snow crab up to a five-year lag. Results indicate that snow crab is largely influenced by temperature during early post-settlement years and becomes increasingly regulated by top-down mechanisms as they approach fishery recruitment. Overall, I conclude that both climate and predation can act as population controls on large decapod populations, but these variables affect decapods at different life stages.
183	A PROBABILISTIC APPROACH TO UNCERTAINTY IN TURBINE EFFICIENCY MEASUREMENT Lakshya Bhatnagar (5930546) 20 June 2022 (has links) <p> Efficiency is an essential metric for assessing turbine performance. Modern turbines rely heavily on numerical computational fluid dynamic (CFD) tools for design improvement. With more compact turbines leading to lower aspect ratio airfoils, the influence of secondary flows is significant on performance. Secondary flows and detached flows, in general, remain a challenge for commercial CFD solvers; hence, there is a need for high fidelity experimental data to tune these solvers used by turbine designers. Efficiency measurements in engine-representative test rigs are challenging for multiple reasons; an inherent problem to any experiment is to remove the effects specific to the turbine rig. This problem is compounded by the narrow uncertainty band required, ideally less than 0.5% uncertainty, to detect the incremental improvements achieved by turbine designers. Efficiency measurements carried out in engine-representative turbine rigs have traditionally relied upon strong assumptions, such as neglecting heat transfer effects. Furthermore, prior to this research there was no framework to compute uncertainty propagation that combines both inputs from experiments and computational tools. </p> <p>This dissertation presents a comprehensive methodology to obtain high-fidelity adiabatic efficiency data in engine-representative turbine facilities. This dissertation presents probabilistic sampling techniques to allow for uncertainty propagation. The effect of rig-specific effects such as heat transfer and gas properties, on efficiency is demonstrated. Sources of uncertainty are identified, and a framework is presented which divides the sources into bias and stochastic. The framework allows the combination of experimental and numerical uncertainty. The accuracy of temperature and aerodynamic pressure probes, used for efficiency determination, is quantified. Corrections for those effects are presented that rely on hybrid numerical and experimental methods. Uncertainty is propagated through these methods using numerical sampling. </p> <p>Finally, two test cases are presented, a stator vane in an annular cascade and a two-stage turbine in a rotating rig. The performance is analyzed using the methods and corrections developed. The uncertainty on the measured efficiency is similar to literature but the uncertainty framework allows an uncertainty estimate on the adiabatic efficiency. </p> Uncertainty Probabilistic Methods Sampling Data Driven Science Gaussian Regression Processes TURBINE efficiency testing Instrumentation measurement technique CFD methods Combined CFD-Experiment temperature thermocouple directional probes five hole probes annular cascade cascades Rotating rig wind tunnel tests
184	Cascades of genetic instability resulting from compromised break-induced replication Vasan, Soumini January 2013 (has links) Indiana University-Purdue University Indianapolis (IUPUI) / Break-induced replication (BIR) is a mechanism to repair double-strand breaks (DSBs) that possess only a single end that can find homology in the genome. This situation can result from the collapse of replication forks or telomere erosion. BIR frequently produces various genetic instabilities including mutations, loss of heterozygosity, deletions, duplications, and template switching that can result in copy-number variations (CNVs). An important type of genomic rearrangement specifically linked to BIR is half crossovers (HCs), which result from fusions between parts of recombining chromosomes. Because HC formation produces a fused molecule as well as a broken chromosome fragment, these events could be highly destabilizing. Here I demonstrate that HC formation results from the interruption of BIR caused by a defective replisome or premature onset of mitosis. Additionally, I document the existence of half crossover instability cascades (HCC) that resemble cycles of non-reciprocal translocations (NRTs) previously described in human tumors. I postulate that HCs represent a potent source of genetic destabilization with significant consequences that mimic those observed in human diseases, including cancer. Comparative Genomic Hybridization Break-induced Replication Copy Number Variations Chromosomal Rearrangements Double-strand Break Repair Half Crossover Homologous Recombination Non-reciprocal Translocation Half crossover instability cascades DNA double-strand break DNA repair Genetic instabilities Array-CGH DNA repair -- Research -- Analysis DNA damage -- Research -- Analysis DNA microarrays -- Research -- Analysis DNA replication -- Regulation DNA -- Analysis Genetic recombination -- Research Mutagenesis -- Research Molecular biology -- Research Mitosis -- Regulation -- Research DNA polymerases DNA -- Synthesis Tumors -- Genetic aspects Cancer -- Genetic aspects
185	Supply Chain Event Management – Bedarf, Systemarchitektur und Nutzen aus Perspektive fokaler Unternehmen der Modeindustrie Tröger, Ralph 10 November 2014 (has links) (PDF) Supply Chain Event Management (SCEM) bezeichnet eine Teildisziplin des Supply Chain Management und ist für Unternehmen ein Ansatzpunkt, durch frühzeitige Reaktion auf kritische Ausnahmeereignisse in der Wertschöpfungskette Logistikleistung und -kosten zu optimieren. Durch Rahmenbedingungen wie bspw. globale Logistikstrukturen, eine hohe Artikelvielfalt und volatile Geschäftsbeziehungen zählt die Modeindustrie zu den Branchen, die für kritische Störereignisse besonders anfällig ist. In diesem Sinne untersucht die vorliegende Dissertation nach einer Beleuchtung der wesentlichen Grundlagen zunächst, inwiefern es in der Modeindustrie tatsächlich einen Bedarf an SCEM-Systemen gibt. Anknüpfend daran zeigt sie nach einer Darstellung bisheriger SCEM-Architekturkonzepte Gestaltungsmöglichkeiten für eine Systemarchitektur auf, die auf den Designprinzipien der Serviceorientierung beruht. In diesem Rahmen erfolgt u. a. auch die Identifikation SCEM-relevanter Business Services. Die Vorzüge einer serviceorientierten Gestaltung werden detailliert anhand der EPCIS (EPC Information Services)-Spezifikation illustriert. Abgerundet wird die Arbeit durch eine Betrachtung der Nutzenpotenziale von SCEM-Systemen. Nach einer Darstellung von Ansätzen, welche zur Nutzenbestimmung infrage kommen, wird der Nutzen anhand eines Praxisbeispiels aufgezeigt und fließt zusammen mit den Ergebnissen einer Literaturrecherche in eine Konsolidierung von SCEM-Nutzeffekten. Hierbei wird auch beleuchtet, welche zusätzlichen Vorteile sich für Unternehmen durch eine serviceorientierte Architekturgestaltung bieten. In der Schlussbetrachtung werden die wesentlichen Erkenntnisse der Arbeit zusammengefasst und in einem Ausblick sowohl beleuchtet, welche Relevanz die Ergebnisse der Arbeit für die Bewältigung künftiger Herausforderungen innehaben als auch welche Anknüpfungspunkte sich für anschließende Forschungsarbeiten ergeben. SCEM Supply Chain Event Management SOA Serviceorientierte Architektur EPCIS EPC Information Services Modeindustrie Bedarf Architektur Systemarchitektur Nutzen SCEM-System Business Services Geschäftsorientierte Services Supply Chain Management SCM Logistik Fokale Unternehmen Bekleidungsindustrie Textilindustrie Logistikleistung Logistikkosten Simulation Service Science Service Design Event Kritisches Ausnahmeereignis Störung Störereignis Lieferkette Wertschöpfungskette Fallstudie EPC Electronic Product Code Cloud Computing Cloud-Infrastruktur Cloud-ERP Service-Identifikation Service-Beschreibung Gerry Weber van Laack Gardeur Seidensticker ThyssenKrupp Deutsche Post DHL fTRACE GS1 GS1 Germany René Lezard März München Kybernetischer Regelkreis Management by Exception Supply Chain Risk Management Supply Network Event Management SNEM Service-Repository Service-Registry Original Brand Manufacturer OBM SaaS Software as a Service RFID Radio Frequency Identification Komplexität Störungsanfälligkeit Nutzenpotenzial SCEM-Lösung Value Chain Integrator Transaktionskostentheorie Ressourcenbasierter Ansatz Theorie der informatorischen Kaskaden Systemtheorie Prinzipal-Agent-Theorie Theorien zur Informationsverarbeitung Nutzenquantifizierung Auto-ID Automatische Identifikation EDI Electronic Data Interchange Event-Typisierung SCEM-Funktionen SCEM-Funktionalitäten Geschäftsprozesse Servicekatalog Servicekandidat Servicespezifikation Standard Schnittstelle Überwachen Melden Steuern Messen Simulieren FMEA Fehlermöglichkeits- und Einflussanalyse SCEM-FMEA Ereignisorientierte Simulation Konfiguration SCEM Supply chain event management SOA Service-oriented architecture EPCIS EPC information services Fashion industry Need Business need Architecture System architecture Benefit SCEM system Business services Business-oriented services Supply chain management SCM Logistics Apparel industry Textile industry Logistics performance Logistics costs Simulation Service science Service design Event Critical exception Deviation Disruption Disruptive event Supply chain Value chain Case study EPC Electronic product code Cloud computing Cloud infrastructure Cloud ERP Service identification Service description Gerry Weber van Laack Gardeur Seidensticker ThyssenKrupp Deutsche Post DHL fTRACE GS1 GS1 Germany René Lezard März München Control system Management by exception Supply chain risk management Supply network event management SNEM Service repository Service registry Original brand manufacturer OBM SaaS Software as a Service RFID Radio Frequency Identification Complexity Vulnerability to disruptions Potential SCEM solution Value chain integrator Transaction cost theory Resource-based view Information cascades System theory Principal-agent theory Information processing AIDC EDI Electronic data interchange Event classification SCEM functions SCEM functionalities Business processes Service catalogue Service candidate Service specification Standard Interface Monitor Notify Simulate Control Measure FMEA Failure mode and effects analysis SCEM FMEA Discrete event simulation Configuration ddc:330 ddc:000 ddc:004 ddc:650
186	Supply Chain Event Management – Bedarf, Systemarchitektur und Nutzen aus Perspektive fokaler Unternehmen der Modeindustrie Tröger, Ralph 17 October 2014 (has links) Supply Chain Event Management (SCEM) bezeichnet eine Teildisziplin des Supply Chain Management und ist für Unternehmen ein Ansatzpunkt, durch frühzeitige Reaktion auf kritische Ausnahmeereignisse in der Wertschöpfungskette Logistikleistung und -kosten zu optimieren. Durch Rahmenbedingungen wie bspw. globale Logistikstrukturen, eine hohe Artikelvielfalt und volatile Geschäftsbeziehungen zählt die Modeindustrie zu den Branchen, die für kritische Störereignisse besonders anfällig ist. In diesem Sinne untersucht die vorliegende Dissertation nach einer Beleuchtung der wesentlichen Grundlagen zunächst, inwiefern es in der Modeindustrie tatsächlich einen Bedarf an SCEM-Systemen gibt. Anknüpfend daran zeigt sie nach einer Darstellung bisheriger SCEM-Architekturkonzepte Gestaltungsmöglichkeiten für eine Systemarchitektur auf, die auf den Designprinzipien der Serviceorientierung beruht. In diesem Rahmen erfolgt u. a. auch die Identifikation SCEM-relevanter Business Services. Die Vorzüge einer serviceorientierten Gestaltung werden detailliert anhand der EPCIS (EPC Information Services)-Spezifikation illustriert. Abgerundet wird die Arbeit durch eine Betrachtung der Nutzenpotenziale von SCEM-Systemen. Nach einer Darstellung von Ansätzen, welche zur Nutzenbestimmung infrage kommen, wird der Nutzen anhand eines Praxisbeispiels aufgezeigt und fließt zusammen mit den Ergebnissen einer Literaturrecherche in eine Konsolidierung von SCEM-Nutzeffekten. Hierbei wird auch beleuchtet, welche zusätzlichen Vorteile sich für Unternehmen durch eine serviceorientierte Architekturgestaltung bieten. In der Schlussbetrachtung werden die wesentlichen Erkenntnisse der Arbeit zusammengefasst und in einem Ausblick sowohl beleuchtet, welche Relevanz die Ergebnisse der Arbeit für die Bewältigung künftiger Herausforderungen innehaben als auch welche Anknüpfungspunkte sich für anschließende Forschungsarbeiten ergeben. info:eu-repo/classification/ddc/330 ddc:330 info:eu-repo/classification/ddc/000 ddc:000 info:eu-repo/classification/ddc/004 ddc:004 info:eu-repo/classification/ddc/650 ddc:650

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