scholarly journals Impact of Chinese and European Airspace Constraints on Trajectory Optimization

Aerospace ◽  
2021 ◽  
Vol 8 (11) ◽  
pp. 338
Author(s):  
Judith Rosenow ◽  
Gong Chen ◽  
Hartmut Fricke ◽  
Xiaoqian Sun ◽  
Yanjun Wang
Keyword(s):  
Trajectory Optimization ◽  
Linear Optimization ◽  
Air Traffic ◽  
Atmospheric Conditions ◽  
Traffic Efficiency ◽  
Horizontal Flight ◽  
A Minor ◽  
Operational Constraints ◽  
Great Circle Distance ◽  
Reference Trajectories

Air traffic trajectory optimization is a complex, multidimensional and non-linear optimization problem and requires a firm focus on the essential criteria. The criteria cover operational, economical, environmental, political, and social factors and differ from continent to continent. Since air traffic is a transcontinental transport system, the criteria may also change during a single flight. Historic flight track data allow observation and assess real flights, to extract essential criteria and to derive optimization strategies to increase air traffic efficiency. Real flight track data from the Chinese and European air traffic show significant differences in the routing structure in both regions. For that reason, reference trajectories of historic ADS-B 24-h air traffic data in China and Europe have been extracted and analyzed regarding horizontal flight efficiency and the most restrictive criteria of trajectory optimization. We found that prohibited areas might be the most powerful reason to describe deviations from the great circle distance in the Chinese air traffic system. Atmospheric conditions, network requirements, aircraft types and flight planning procedures are similar in China and Europe and only have a minor impact on flight efficiency during the cruise phase. In a multi-criteria trajectory optimization of the extracted reference trajectories considering the weather, operational constraints and prohibited areas, we found that flown ground distances could be reduced by 255 km in the Chinese airspace and 2.3 km in the European airspace. The resultant reference trajectories can be used for further analysis to increase the efficiency of continental air traffic flows.

scholarly journals Advanced Flight Planning and the Benefit of In-Flight Aircraft Trajectory Optimization

2021 ◽  
Vol 13 (3) ◽  
pp. 1383
Author(s):  
Judith Rosenow ◽  
Martin Lindner ◽  
Joachim Scheiderer
Keyword(s):  
New York ◽  
Traffic Control ◽  
Traffic Management ◽  
Trajectory Optimization ◽  
Service Providers ◽  
Weather Conditions ◽  
Air Traffic ◽  
Weather Data ◽  
Weather Forecasts ◽  
Aircraft Trajectory

The implementation of Trajectory-Based Operations, invented by the Single European Sky Air Traffic Management Research program SESAR, enables airlines to fly along optimized waypoint-less trajectories and accordingly to significantly increase the sustainability of the air transport system in a business with increasing environmental awareness. However, unsteady weather conditions and uncertain weather forecasts might induce the necessity to re-optimize the trajectory during the flight. By considering a re-optimization of the trajectory during the flight they further support air traffic control towards achieving precise air traffic flow management and, in consequence, an increase in airspace and airport capacity. However, the re-optimization leads to an increase in the operator and controller’s task loads which must be balanced with the benefit of the re-optimization. From this follows that operators need a decision support under which circumstances and how often a trajectory re-optimization should be carried out. Local numerical weather service providers issue hourly weather forecasts for the coming hour. Such weather data sets covering three months were used to re-optimize a daily A320 flight from Seattle to New York every hour and to calculate the effects of this re-optimization on fuel consumption and deviation from the filed path. Therefore, a simulation-based trajectory optimization tool was used. Fuel savings between 0.5% and 7% per flight were achieved despite minor differences in wind speed between two consecutive weather forecasts in the order of 0.5 m s−1. The calculated lateral deviations from the filed path within 1 nautical mile were always very small. Thus, the method could be easily implemented in current flight operations. The developed performance indicators could help operators to evaluate the re-optimization and to initiate its activation as a new flight plan accordingly.

scholarly journals Walking Trajectory Optimization With Rotation of the Feet for a Planar Bipedal Robot With Four-Bar Knees

2012 ◽  
Author(s):  
Arnaud Hamon ◽  
Yannick Aoustin
Keyword(s):  
Knee Joint ◽  
Trajectory Optimization ◽  
The Other ◽  
Bipedal Robot ◽  
Double Support ◽  
Walking Gait ◽  
Parametric Optimization Problem ◽  
Four Bar Linkage ◽  
Reference Trajectories ◽  
Support Phase

The design of a knee joint is a key issue in robotics and biomechanics to improve the compatibility between prosthesis and human movements and to improve the bipedal robot performances. We propose a novel design for the knee joint of a planar bipedal robot, based on a four-bar linkage. The dynamic model of the planar bipedal robot is calculated. We design walking reference trajectories with double support phases, single supports with a flat contact of the foot in the ground and single support phases with rotation of the foot around the toe. During the double support phase, both feet rotate. This phase is ended by an impact on the ground of the toe of one foot, the other foot taking off. The single support phase is ended by an impact of the swing foot heel, the other foot keeping contact with the ground through its toe. For both gaits, the reference trajectories of the rotational joints are prescribed by polynomial functions in time. A parametric optimization problem is presented for the determination of the parameters corresponding to the optimal cyclic walking gaits. The main contribution of this paper is the design of a dynamical stable walking gait with double support phases with feet rotation, impacts and single support phases for this novel bipedal robot.

scholarly journals Current glacier recession causes significant rockfall increase: The immediate paraglacial response of deglaciating cirque walls

2020 ◽  
Author(s):  
Ingo Hartmeyer ◽  
Robert Delleske ◽  
Markus Keuschnig ◽  
Michael Krautblatter ◽  
Andreas Lang ◽  
...  
Keyword(s):  
Minor Effect ◽  
European Alps ◽  
Atmospheric Conditions ◽  
Glacier Surface ◽  
Terrestrial Lidar ◽  
Physical Weathering ◽  
Ice Surface ◽  
Recent Climate ◽  
Ample Supply ◽  
A Minor

Abstract. In the European Alps almost half the glacier volume disappeared over the past 150 years. The loss is reflected in glacier retreat and ice surface lowering even at high altitude. In steep glacial cirques surface lowering exposes rock to atmospheric conditions for the very first time in many millennia. Instability of rockwalls has long been identified as one of the direct consequences of deglaciation, but so far cirque-wide quantification of rockfall at high-resolution is missing. Based on terrestrial LiDAR a rockfall inventory for the permafrost-affected rockwalls of two rapidly deglaciating cirques in the Central Alps of Austria (Kitzsteinhorn) is established. Over six-years (2011–2017) 78 rockwall scans were acquired to generate data of high spatial and temporal resolution. 632 rockfalls were registered ranging from 0.003 to 879.4 m³, mainly originating from pre-existing structural rock weaknesses. 60 % of the rockfall volume detached from less than ten vertical meters above the glacier surface, indicating enhanced rockfall activity over tens of years following deglaciation. Debuttressing seems to play a minor effect only. Rather, preconditioning is assumed to start inside the Randkluft (gap between cirque wall and glacier) where sustained freezing and ample supply of liquid water likely cause enhanced physical weathering and high plucking stresses. Following deglaciation, pronounced thermomechanical strain is induced and an active layer penetrates into the formerly perennially frozen bedrock. These factors likely cause the observed paraglacial rockfall increase close to the glacier surface. This paper presents the most extensive dataset of high-alpine rockfall to date and the first systematic documentation of a cirque-wide erosion response of glaciated rockwalls to recent climate warming.

scholarly journals In-Flight Aircraft Trajectory Optimization within Corridors Defined by Ensemble Weather Forecasts

Aerospace ◽  
2020 ◽  
Vol 7 (10) ◽  
pp. 144 ◽  
Author(s):  
Martin Lindner ◽  
Judith Rosenow ◽  
Thomas Zeh ◽  
Hartmut Fricke
Keyword(s):  
Traffic Control ◽  
Traffic Management ◽  
Trajectory Optimization ◽  
Air Traffic ◽  
Weather Data ◽  
Parameter Uncertainties ◽  
Weather Forecasts ◽  
Fuel Savings ◽  
Flight Plan ◽  
Aircraft Trajectory

Today, each flight is filed as a static route not later than one hour before departure. From there on, changes of the lateral route initiated by the pilot are only possible with air traffic control clearance and in the minority. Thus, the initially optimized trajectory of the flight plan is flown, although the optimization may already be based upon outdated weather data at take-off. Global weather data as those modeled by the Global Forecast System do, however, contain hints on forecast uncertainties itself, which is quantified by considering so-called ensemble forecast data. In this study, the variability in these weather parameter uncertainties is analyzed, before the trajectory optimization model TOMATO is applied to single trajectories considering the previously quantified uncertainties. TOMATO generates, based on the set of input data as provided by the ensembles, a 3D corridor encasing all resulting optimized trajectories. Assuming that this corridor is filed in addition to the initial flight plan, the optimum trajectory can be updated even during flight, as soon as updated weather forecasts are available. In return and as a compromise, flights would have to stay within the corridor to provide planning stability for Air Traffic Management compared to full free in-flight optimization. Although the corridor restricts the re-optimized trajectory, fuel savings of up to 1.1%, compared to the initially filed flight, could be shown.

scholarly journals Initial steps of aerosol growth

2004 ◽  
Vol 4 (11/12) ◽  
pp. 2553-2560 ◽  
Author(s):  
M. Kulmala ◽  
L. Laakso ◽  
K. E. J. Lehtinen ◽  
I. Riipinen ◽  
M. Dal Maso ◽  
...  
Keyword(s):  
Growth Rate ◽  
Atmospheric Aerosols ◽  
Minor Role ◽  
Forest Site ◽  
Atmospheric Conditions ◽  
Curvature Effects ◽  
Atmospheric Nucleation ◽  
Condensational Growth ◽  
A Minor ◽  
20 Nm

Abstract. The formation and growth of atmospheric aerosols depend on several steps, namely nucleation, initial steps of growth and subsequent – mainly condensational – growth. This work focuses on the initial steps of growth, meaning the growth right after nucleation, where the interplay of curvature effects and thermodynamics has a significant role on the growth kinetics. More specifically, we investigate how ion clusters and aerosol particles grow from 1.5 nm to 20 nm (diameter) in atmospheric conditions using experimental data obtained by air ion and aerosol spectrometers. The measurements have been performed at a boreal forest site in Finland. The observed trend that the growth rate seems to increase as a function of size can be used to investigate possible growth mechanisms. Such a growth rate is consistent with a recently suggested nano-Köhler mechanism, in which growth is activated at a certain size with respect to condensation of organic vapors. The results also imply that charge-enhanced growth associated with ion-mediated nucleation plays only a minor role in the initial steps of growth, since it would imply a clear decrease of the growth rate with size. Finally, further evidence was obtained on the earlier suggestion that atmospheric nucleation and the subsequent growth of fresh nuclei are likely to be uncoupled phenomena via different participating vapors.

DirCol5i: Trajectory Optimization for Problems With High-Order Derivatives

2018 ◽  
Vol 141 (3) ◽  
Author(s):  
Matthew P. Kelly
Keyword(s):  
Nonlinear System ◽  
Trajectory Optimization ◽  
Optimization Problems ◽  
High Order ◽  
Robot Arm ◽  
Minimum Jerk ◽  
Higher Derivatives ◽  
A Chain ◽  
Fifth Order ◽  
Reference Trajectories

In this technical brief, we focus on solving trajectory optimization problems that have nonlinear system dynamics and that include high-order derivatives in the objective function. This type of problem comes up in robotics—for example, when computing minimum-snap reference trajectories for a quadrotor or computing minimum-jerk trajectories for a robot arm. DirCol5i is a transcription method that is specialized for solving this type of problem. It uses the fifth-order splines and analytic differentiation to compute higher-derivatives, rather than using a chain-integrator as would be required by traditional methods. We compare DirCol5i to traditional transcription methods. Although it is slower for some simple optimization problems, when solving problems with high-order derivatives DirCol5i is faster, more numerically robust, and does not require setting up a chain integrator.

scholarly journals A climatology of formation conditions for aerodynamic contrails

2013 ◽  
Vol 13 (21) ◽  
pp. 10847-10857 ◽  
Author(s):  
K. Gierens ◽  
F. Dilger
Keyword(s):  
Climate Impact ◽  
Reanalysis Data ◽  
Air Traffic ◽  
Liquid Droplets ◽  
Atmospheric Conditions ◽  
Climate Effect ◽  
Ice Clouds ◽  
Formation Conditions ◽  
The Tropics ◽  
Global Reanalysis

Abstract. Aircraft at cruise levels can cause two kinds of contrails, the well known exhaust contrails and the less well-known aerodynamic contrails. While the possible climate impact of exhaust contrails has been studied for many years, research on aerodynamic contrails began only a few years ago and nothing is known about a possible contribution of these ice clouds to climate impact. In order to make progress in this respect, we first need a climatology of their formation conditions and this is given in the present paper. Aerodynamic contrails are defined here as line shaped ice clouds caused by aerodynamically triggered cooling over the wings of an aircraft in cruise which become visible immediately at the trailing edge of the wing or close to it. Effects at low altitudes like condensation to liquid droplets and their potential heterogeneous freezing are excluded from our definition. We study atmospheric conditions that allow formation of aerodynamic contrails. These conditions are stated and then applied to atmospheric data: first to a special case where an aerodynamic contrail was actually observed and then to a full year of global reanalysis data. We show where, when (seasonal variation), and how frequently (probability) aerodynamic contrails can form, and how this relates to actual patterns of air traffic. We study the formation of persistent aerodynamic contrails as well. Furthermore, we check whether aerodynamic and exhaust contrails can coexist in the atmosphere. We show that visible aerodynamic contrails are possible only in an altitude range between roughly 540 and 250 hPa, and that the ambient temperature is the most important parameter, not the relative humidity. Finally, we argue that currently aerodynamic contrails have a much smaller climate effect than exhaust contrails, which may however change in future with more air traffic in the tropics.

Geographical area selection and construction of a corresponding routing grid used for in-flight management system flight trajectory optimization

2016 ◽  
Vol 231 (5) ◽  
pp. 809-822
Author(s):  
Bogdan D Dancila ◽  
Ruxandra M Botez
Keyword(s):  
Traffic Management ◽  
Trajectory Optimization ◽  
Management System ◽  
Optimization Algorithms ◽  
Geographical Area ◽  
Atmospheric Conditions ◽  
Flight Trajectory ◽  
Trajectory Data ◽  
Design Variables ◽  
Grid Nodes

This paper proposes a new method for selecting an ellipse-shaped geographical area and constructing a routing grid that circumscribes the contour of the designated area. The resulting grid describes the set of points used by the flight trajectory optimization algorithms to determine an aircraft’s optimal flight trajectory as a function of given particular atmospheric conditions. This method was developed with the intent of its employment in the context of Flight Management System trajectory optimization algorithms, but can be used in Air Traffic Management environments as well. The routing grid limits the trajectory’s maximal total ground distance (between the departure and destination airports), maximizes the geographical area (for a better consideration of the wind conditions) and minimizes the number of grid nodes. The novelty of the proposed method resides in the fact that it allows a distinct and independent parameterization and control of the ellipse’s total surface, and the required size of the take-off/landing procedure maneuvering areas at the departure/destination airports. The ellipse contour constructed using this method is, therefore, well adapted to the particular configuration of the trajectory for which the optimization is performed. Each design variables’ influence is presented, as well as a set of routing grids generated for trajectories corresponding to different total flight distances, and were further compared with real flight trajectory data retrieved using the website Flight Aware.

A 10-W S-band class-B GaN amplifier with a dynamic gate bias circuit for linearity enhancement

2013 ◽  
Vol 6 (1) ◽  
pp. 3-11 ◽  
Author(s):  
Pierre Medrel ◽  
Audrey Martin ◽  
Tibault Reveyrand ◽  
Guillaume Neveux ◽  
Denis Barataud ◽  
...  
Keyword(s):  
Output Power ◽  
Trajectory Optimization ◽  
High Efficiency ◽  
Average Power ◽  
Gate Bias ◽  
Error Vector Magnitude ◽  
Power Added Efficiency ◽  
Class B ◽  
Band Class ◽  
A Minor

In the present paper, we present a dynamic gate biasing technique applied to a 10 W, S-band GaN amplifier. The proposed methodology addresses class-B operation of power amplifiers that offers the potential for high efficiency but requires a careful attention to maintain good linearity performances at large output power back-off. This work proposes a solution to improve the linearity of class-B amplifiers driven by radio frequency-modulated signals having large peak to average power ratios. An important aspect of this work concerns the characterization of the dynamic behavior of GaN devices for gate bias trajectory optimization. For that purpose, the experimental study reported here is based on the use of a time-domain envelope setup. A specific gate bias circuit has been designed and connected to a 10 W – 2.5 GHz GaN amplifier demo board from CREE. Compared to conventional class-B operation with a fixed gate bias, a 10-dB improvement in terms of third-order intermodulation is reached. When applied to the amplification of 16-QAM signals the proposed technique demonstrates significant ACPR reduction of order of 6 dB along with error vector magnitude (EVM) improvements of five points over 8 dB output power back-off with a minor impact on power-added efficiency performances.

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