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

Optical and magnetic tweezers for applications in single-molecule biophysics and nanotechnology

Tesis doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Física de la Materia Condensada. Fecha de lectura: 22-01-201

Chi hotspots trigger a conformational change in the helicase-like domain of AddAB to activate homologous recombination

In bacteria, the repair of double-stranded DNA breaks is modulated by Chi sequences. These are recognised by helicase-nuclease complexes that process DNA ends for homologous recombination. Chi activates recombination by changing the biochemical properties of the helicase-nuclease, transforming it from a destructive exonuclease into a recombination-promoting repair enzyme. This transition is thought to be controlled by the Chi-dependent opening of a molecular latch, which enables part of the DNA substrate to evade degradation beyond Chi. Here, we show that disruption of the latch improves Chi recognition efficiency and stabilizes the interaction of AddAB with Chi, even in mutants that are impaired for Chi binding. Chi recognition elicits a structural change in AddAB that maps to a region of AddB which resembles a helicase domain, and which harbours both the Chi recognition locus and the latch. Mutation of the latch potentiates the change and moderately reduces the duration of a translocation pause at Chi. However, this mutant displays properties of Chi-modified AddAB even in the complete absence of bona fide hotspot sequences. The results are used to develop a model for AddAB regulation in which allosteric communication between Chi binding and latch opening ensures quality control during recombination hotspot recognition

MITIGATION OF AVIATION’S CLIMATE IMPACT THROUGH ROBUST CLIMATE OPTIMIZED TRAJECTORIES IN INTRA-EUROPEAN AIRSPACE

Aircraft trajectories are currently flown and optimized to reduce operating costs, keeping engine CO2-emissions from burnt fuel at a minimum by following fuel optimized routes under consideration of wind. However, research has shown that the location and time of non-CO2 emissions such as NOx, water vapor or the formation of contrail cirrus contribute to about two thirds of aviation’s induced climate impact [1]. Consequently, one option to reduce this impact on a short time horizon is operational measures that aim to optimize aircraft trajectories with regard to climate impact by avoiding atmospheric regions that are especially sensitive to non-CO2 emissions from aviation. For this purpose, the effects of individual emission species need to be quantified in order to assess the mitigation potential by climate-optimized routing. For this reason, multi-dimensional algorithmic climate change functions, which allow for the quantification of the climate impact of emissions, based on meteorological parameters which are available from weather forecast data is used. These algorithmic climate change functions are integrated into the cost functional of a trajectory planning algorithm which is based on an optimal control approach and applied in order to estimate climate optimized aircraft trajectories trading climate impact reduction against cost increase. Since the climate impact and therefore the algorithmic climate change functions are highly dependent on the prevailing atmospheric conditions, particularly the formation of contrail cirrus, weather prediction uncertainties are considered in order to determine robust eco- efficient trajectories. Within this study, the methodology and optimization applied to determine such a robust solution are presented and results are analyzed for an exemplary intra-European flight route

MITIGATION OF AVIATIONS CLIMATE IMPACT THROUGH ROBUST CLIMATE OPTIMIZED TRAJECTORIES IN INTRA-EUROPEAN AIRSPACE

Global aviation actively contributes to anthropogenic global warming. Climate impact mitigation potential has been previously studied and quantitative estimates were determined. However, these estimates are associated with uncertainties in climate impact modelling and weather forecast. In this study, a methodology to consider these uncertainties when optimising trajectories in European airspace is presented

Comparing and combining different climate mitigation measures in aviation

In the context of aviation’s significant contribution to anthropogenic climate change from CO2 and non-CO2 emissions, ambitious climate goals have been defined for the aviation industry that require an implementation of extensive measures from technical, regulatory and operational perspectives. While technical innovations including new aircraft designs and alternative fuels are expected to contribute significantly in the long run as they are associated with late entry-into-service, operational measures can benefit from their fast implementation with the current world fleet. Regulatory implementation enablers can further support the required changes to the air transport system. While the current state of research comprises a broad variety of studies on individual climate mitigation measures, a direct comparison and combination of the achieved results is typically not directly possible due to different reference cases, application scopes, and modelling assumptions as well as different maturities and expected realization times. However, a direct comparability is required to identify especially effective and efficient measures as well as to combine individual approaches in order to compare the resulting potentials towards the defined climate goals. This study aims to address the lack of comparability by developing an approach to compare and combine different climate mitigation measures. We consider different concepts addressing technical, operational as well as regulatory aspects. Based on the individual assessment of climate mitigation measures, we expand a previously developed generalization approach to scale individual results from measures-specific studies to a comparable scope considering varying traffic samples, assessment methods as well as temporal and spatial boundary conditions of the individual studies. Differences in maturities and possible entry-into-service times are also incorporated. Hence, different combinations of mitigation measures can be analysed regarding their climate mitigation potential in terms of temperature change as well as their operational applicability. Finally, possible combinations of the selected measures can be contrasted with defined climate goals

A Landau-Squire nanojet

Fluid jets are found in nature at all length scales, from microscopic to cosmological. Here we report on an electroosmotically driven jet from a single glass nanopore about 75 nm in radius with a maximum flow rate ~15 pL/s. A novel anemometry technique allows us to map out the vorticity and velocity fields that show excellent agreement with the classical Landau-Squire solution of the Navier Stokes equations for a point jet. We observe a phenomenon that we call flow rectification: an asymmetry in the flow rate with respect to voltage reversal. Such a nanojet could potentially find applications in micromanipulation, nanopatterning, and as a diode in microfluidic circuits.Comment: 20 pages, 4 figure

Climate impact assessment of varying cruise flight altitudes applying the CATS simulation approach

The present paper describes a comprehensive assessment and modelling approach that was developed in the DLR project Climate compatible Air Transport System (CATS) with the goal to analyze different options to reduce the climate impact of aviation. The CATS simulation chain is applied to assess the climate impact reduction potential (via CO2, contrail-cirrus, H2O, NOx, ozone, methane, primary mode ozone) for the world fleet of a representative long-range aircraft operated on a global route network in the year 2006. The average temperature response (ATR) and the direct operating costs (DOC) are calculated for flights with varying cruise flight altitudes and speeds. The obtained results are expressed as relative changes with respect to the minimum DOC trajectory and assessed as cost-benefit ratio (ATR vs. DOC). The results are highlighted for a single route and transferred to the global route network, showing a large potential to reduce the climate impact of aviation for small to moderate increments on costs

Implementation of eco-efficient procedures to mitigate the climate impact of non-CO2 effects

Within this study, the lack of incentivizing airlines to internalize their climate costs is tried to be closed by the introduction of climate-charged airspaces, as non-CO2 emissions have locationand time-dependent effects upon the climate. In order to create an incentive for airlines to minimize flight time and emissions in highly climatesensitive regions, a climate charge is imposed for airlines when operating in these areas. Costminimizing airlines are expected to re-route their flights to reduce their climate charges and hence cash operating costs. Accordingly, this leads to the desired outcome of incentivizing climate mitigation and even of driving technological innovation towards cleaner technologies. The evaluation of the climate impact mitigation potential of climate-charged airspaces is performed based on optimal control techniques. Climate sensitivities are expressed by climate change functions characterizing the climate impact caused by an emission at a certain location and time. The cost-benefit potential (climate impact mitigation vs. rise in operating costs) is investigated for a Transatlantic route and benchmarked against climate-optimized trajectories