Anaerobic oxidation of methane in the Concepcion Methane Seep Area, Chilean continental margin

Within subduction zones of active continental margins, large amounts of methane can be mobilized by dewatering processes and transported to the seafloor along migration pathways. A recently discovered seep area located off Concepción (Chile) at water depth between 600 to 1100 mbsl is characterized by active methane vent sites as well as massive carbonates boulders and plates which probably are related to methane seepage in the past. During the SO210 research expedition “Chiflux” (Sept-Oct 2010), sediment from the Concepción Methane Seep Area (CSMA) at the fore arc of the Chilean margin was sampled to study microbial activity related to methane seepage. We sampled surface sediments (0-30cm) from sulfur bacteria mats, as well as clam, pogonophoran, and tubeworm fields with push cores and a TV-guided multicorer system. Anaerobic oxidation of methane (AOM) and sulfate reduction rates were determined using ex-situ radioisotope tracer techniques. Additionally, porewater chemistry of retrieved cores as well as isotopic composition and age record of surrounding authigenic carbonates were analyzed. The shallowest sulfate-methane-transition zone (SMTZ) was identified at 4 cm sediment depth hinting to locally strong fluid fluxes. However, a lack of Cl- anomalies in porewater profiles indicates a shallow source of these fluids, which is supported by the biogenic origin of the methane (�13C -70h PDB). Sulfide and alkalinity was relatively high (up to 20 mM and 40 mEq, respectively). Rates of AOM and sulfate reduction within this area reached magnitudes typical for seeps with variation between different habitat types, indicating a diverse methane supply, which is affecting the depths of the SMTZ. Rates were highest at sulfur a bacteria mats (20 mmol m-2 d-1) followed by a large field of dead clams, a pogonophoran field, a black sediment spot, and a carbonate rich clam field. Lowest rates (0.2 mmol m-2 d-1) were measured in close vicinity to these hot spots. Abundant massive carbonate blocks and plates hint to a very old seep system with a probably much higher activity in the past. The U-Th age record of these authigenic carbonates reach back to periods of venting activity with more than 150 ka ago. Carbon isotopic signatures of authigenic carbonates (�13C -50 to -40hPDB) suggest a biogenic carbon source (i.e. methane), also in the past. We found several indications for the impact of recent earthquakes within the seep area (cracks, shifted seafloor), which could be an important mechanism for the triggering of new seepage activity, change in fluid expulsion rates and colonization patterns of the cold seep fauna

Erweiterung eines Trajektorienrechners zur Nutzung meteorologischer Daten für die Optimierung von Flugzeugtrajektorien

Das Fliegen wird maßgeblich durch die Wind- und Wettersituation entlang des Flugweges beeinflusst. Vor diesem Hintergrund wurde das Trajectory Calculation Module (TCM) – ein bestehendes Werkzeug zur Simulation von Flugtrajektorien – dahingehend erweitert, dass im Zuge der Trajektoriensimulation anstelle von Standardatmosphären-Bedingungen auch reale atmosphärische Bedingungen miteinbezogen werden können. Hierfür wurden insbesondere eine Flughöhen- sowie eine Fluggeschwindigkeitsregelung integriert, die die Einhaltung typischer Flugphasenrandbedingungen auch unter von der Standardatmosphäre abweichenden meteorologischen Bedingungen gewährleisten. Die Wirkung horizontaler Winde wurde zudem durch deren Superposition mit der Fluggeschwindigkeit gegenüber der Luft erfasst. Ferner wurde für die laterale Optimierung von Flugrouten unter Windeinfluss ein Algorithmus auf Basis von Prinzipien der Optimalsteuerungstheorie entwickelt. Das zu minimierende Kostenfunktional wurde so gewählt, dass sowohl die Flugzeit als auch der Einfluss einer ortsabhängigen Straffunktion Berücksichtigung finden können. Als Anwendungsfall wurden Klimakostenfunktionen, die die Sensitivität der Klimawirkung gegenüber der Emission von Schadstoffen als Funktion des Ortes beschreiben, als Straffunktion in das Kostenfunktional der Optimierung integriert. Auf dieser Grundlage wurde anhand einer exemplarischen Flugroute untersucht, inwieweit sich die durch den Flug verursachte Klimawirkung vermindern ließe, wenn eine erhöhte Flugzeit in Kauf genommen würde

Temperature dependence of the static and dynamic behaviour in a quenching and partitioning processed low-Si Steel

Because of their excellent combination of strength and ductility, quenching and partitioning (Q & P) steels have a great chance of being added to the third generation of advanced high strength steels. The large ductility of Q & P steels arises from the presence of 10% to 15% of retained austenite which postpones necking due to the transformation induced plasticity (TRIP) effect. Moreover, Q & P steels show promising forming properties with favourable Lankford coefficients, while their planar anisotropy is low due to a weak texture. The stability of the metastable austenite is the key to obtain tailored properties for these steels. To become part of the newest generation of advanced high strength steels, Q & P steels have to preserve their mechanical properties at dynamic strain rates and over a wide range of temperatures. Therefore, in the present study, a low-Si Q & P steel was tested at temperatures from -40 degrees C to 80 degrees C and strain rates from 0.001 s(-1) to 500 s(-1). Results show that the mechanical properties are well-preserved at the lowest temperatures. Indeed, at -40 degrees C and room temperature, no significant loss of the deformation capacity is observed even at dynamic strain rates. This is attributed to the presence of a large fraction of austenite that is so (thermally) stable that it does not transform in the absence of deformation. In addition, the high stability of the austenite decreases the elongation at high test temperatures (80 degrees C). The additional adiabatic heating in the dynamic tests causes the largest reduction of the uniform strain for the samples tested at 80 degrees C. Quantification of the retained austenite fraction in the samples after testing confirmed that, at the highest temperature and strain rate, the TRIP effect is suppressed

Supersonic Overland Without a Sonic Boom – Quantifying the Speed Advantage of Mach-Cutoff Flight

When flying at low supersonic speeds, rising temperatures and convenient winds can deflect the sonic boom shock waves so that they do not reach the ground. This work presents a computation methodology that incorporates atmospheric sonic ray tracing, topography, and realistic 3-D atmospheres in order to optimize supersonic overland cruise with respect to speed. Flight missions are simulated on several suitable city pairs using numerous atmospheric conditions. Flight times and fuel consumption are compared to subsonic high-speed missions

Machine Learning Application in Air Traffic Management Resiliency based on Capacity Regulations

There is a considerable interest in air transportation resilience as a mechanism to cope with the consequences of disruptions to local authorities. Although the identification of metrics and baselines for measuring resilience are still regarded as challenges, we believe that the meaning of disruptions is no longer driven solely by safety threats but also by emergent performance issues. In this paper, resilience of the European Air Traffic Management Network (EATMN) is studied from a performance perspective. In fact, improved predictability and reliability of planning data across the EATMN, allow reduction of reserved Air Traffic Management (ATM) capacity. Consequently, the management of emergent demand-capacity imbalances, regarded as disruptions, is added to tactical phase of Air Fraffic Flow and Capacity Management (ATFCM). In this phase of operations (i.e. day-of-operations) a limited number of variables are available to form aggregated indicators for network resilience. We consider that available ATFCM regulations data reveal restorative mechanisms for tactical Demand-Capacity Balancing (DCB). Aggregated indicators are regarded as enablers to monitor the resilient management of Area Control Centers and to observe spatial distribution of network resiliency. This paper presents an exploratory effort of the needed situational awareness by exploring supervised learning techniques in the context of ATFCM regulations to predict Air Traffic Flow Management (ATFM) delay. In particular, it focuses on the application of machine learning algorithms and comparison of different architecture variants to a regression study on tactical DCB disruptions

An explanatory approach to modeling the fleet assignment in the global air transportation system

Airlines’ fleet assignment heavily affects the economic and ecological performance of the global air transportation system (ATS). Consequently, it is inevitable to include potential changes of the fleet assignment when modeling and assessing future global ATS scenarios. Therefore, this article presents a novel explanatory approach to modeling the fleet assignment in the global ATS. The presented approach is based on formulating and solving an optimization problem, which describes the fleet assignment in the ATS through a suitable combination of objective function and constraints. While the objective function combines both the airline and the passenger perspective on the fleet assignment, the constraints include additional operational and technological aspects. In comparison to the available global fleet assignment models in the literature, which rely on statistical approaches, the advantages of the presented approach via an optimization problem lie in the overall scenario capability and the consideration of explicit aircraft types instead of simplifying seat categories. To calibrate and validate our model, we use 10 years of historic flight schedule data. The results underline the strengths and weaknesses of the presented approach and indicate potential for future improvement

Entwicklung des Luftverkehrs in Deutschland

DLR-Institut für Luftverkehr Historische Entwicklung des globalen Luftverkehrs (ab 1950) und nach Weltregionen (ab 2002) Vergleich „vor Covid-19“ (Januar-August 2019) mit „nach Covid-19“ (Januar-August 2023): Passagieraufkommen (Deutschland, EU27 und Welt) Starts pro Tag (Deutschland, Europa) Passagieraufkommen und Marktanteile der Low Cost Carrier innerhalb der EU27 (Deutschland, EU27) Passagieraufkommen und Passagiere pro Flug (innerdeutsch, nach Westeuropa, in die restliche Welt) Inländisches Passagieraufkommen im EU27-Vergleich Mögliche Gründe der schwachen Aufkommensentwicklung in Deutschland Ausblick: Globale Luftverkehrsprognose bis 205

VocDoc, what happened to my voice? Towards automatically capturing vocal fatigue in the wild

Objective: Voice problems that arise during everyday vocal use can hardly be captured by standard outpatient voice assessments. In preparation for a digital health application to automatically assess longitudinal voice data ‘in the wild’ – the VocDoc, the aim of this paper was to study vocal fatigue from the speaker’s perspective, the healthcare professional’s perspective, and the ‘machine’s’ perspective. Methods: We collected data of four voice healthy speakers completing a 90-min reading task. Every 10 min the speakers were asked about subjective voice characteristics. Then, we elaborated on the task of elapsed speaking time recognition: We carried out listening experiments with speech and language therapists and employed random forests on the basis of extracted acoustic features. We validated our models speaker-dependently and speaker-independently and analysed underlying feature importances. For an additional, clinical application-oriented scenario, we extended our dataset for lecture recordings of another two speakers. Results: Self- and expert-assessments were not consistent. With mean F1 scores up to 0.78, automatic elapsed speaking time recognition worked reliably in the speaker-dependent scenario only. A small set of acoustic features – other than features previously reported to reflect vocal fatigue – was found to universally describe long-term variations of the voice. Conclusion: Vocal fatigue seems to have individual effects across different speakers. Machine learning has the potential to automatically detect and characterise vocal changes over time. Significance: Our study provides technical underpinnings for a future mobile solution to objectively capture pathological long-term voice variations in everyday life settings and make them clinically accessible

Climate-Optimised Intermediate Stop Operations: Mitigation Potential and Differences from Fuel-Optimised Configuration

Saving fuel by splitting a flight mission with an intermediate stop for refuelling is described by the concept of intermediate stop operations. This can also be beneficial to the climate impact of aviation, if the flight level and intermediate stop airport are selected accordingly. This study aims to estimate the mitigation potential of an implementation of climate-optimised intermediate stop operations for European long-haul flights and compare it to fuel-optimal operations. For this purpose, fuel consumption and emissions are simulated along four-dimensional trajectories for the selected annual flight plan, and their average temperature response is calculated. A comparison between the reference case and climate-optimised as well as fuel-optimised scenarios shows a significant climate mitigation potential and reveals a shift of trajectories to lower latitudes and altitudes. However, increased flight times and fuel consumption limit implementation from stakeholders’ perspectives

FlyATM4E (SESAR ER) - Mitigating aviation climate impact by climate-optimized aircraft trajectories

Darstellung des Projekts FlyATM4