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Generalised Error Functions from the Kerr Metric

Chinese Physics Letters 2016年第3期33卷 12-16页

作者：唐文林罗子人刘润球 Science and Technology on Aerospace Flight Dynamics Laboratory Beijing Aerospace Control Center Department of Aerospace Guidance Navigation and Control School of AstronauticsBeihang University QUEST Center of Quantum Engineering and Space-Time Research Leibniz Universitt Hannover Max Planck Institute for Gravitational Physics(Albert Einstein Institute) Institute of Applied Mathematics Morningside Center of Mathematics and LESCInstitute of Computational MathematicsAcademy of Mathematics and System ScienceChinese Academy of Sciences

Motivated by the effort to understand the mathematical structure underlying the Teukolsky equations in a Kerr metric background, a homogeneous integral equation related to the prolate spheroidal function is studied. From the consideration of the Fredholm determinant of the integral equation, a family of generalized error function is defined, with which the Fredholm determinant of the sinc kernel is also evaluated. An analytic solution of a special ease of the fifth Painlev~ transcendent is then worked out explicitly.

关键词： of is exp in Generalised Error Functions from the Kerr Metric from

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A heat wave problem for a degenerate nonlinear parabolic equation with a specified source function

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AIP Conference Proceedings 2018年第1期2053卷

作者： A. L. Kazakov P. A. Kuznetsov L. F. Spevak 1Matrosov Institute for System Dynamics and Control Theory Siberian Branch of the Russian Academy of Sciences 134 Lermontova St. 664033 Irkutsk Russia 2Institute of Engineering Science Ural Branch of the Russian Academy of Sciences 34 Komsomolskaya St. 620049 Ekaterinburg Russia

A nonlinear parabolic heat conduction equation with a source is discussed, for which solutions of the heat wave propagating against a cold background at a finite velocity are studied. A new theorem of the existence and uniqueness of heat waves is proved. A particular case is studied in detail, when the heat wave is invariant and its construction reduces to solving an ordinary differential equation. For the numerical construction of invariant heat waves, an algorithm based on the boundary element method is proposed. Test examples are solved.

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Fireworks algorithm for the satellite link scheduling problem in the navigation constellation

Fireworks algorithm for the satellite link scheduling proble...

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2016 IEEE Congress on Evolutionary Computation, CEC 2016

作者： Zhang, Tianjiao Ke, Liangjun Li, Jisheng Li, Jing Li, Zexi Huang, Jingqi State Key Laboratory of Astronautic Dynamics Xi'An Satellite Control Center and System Engineering Institute xi'An Jiaotong University xi'An 710043 China State Key Laboratory for Manufacturing Systems Engineering Xi'An Jiaotong University Xi'An710043 China State Key Laboratory of Astronautic Dynamics Xi'An Satellite Control Center Xi'An710049 China

ISBN: (纸本)9781509006229

Global navigation satellite system (GNSS) can provide autonomous geo-spatial positioning and time synchronization services for both civil and military uses. Satellite links in GNSS are used to transmit signal for constellation management and other applications. In this work, we focus on solving the satellite link scheduling problem over dynamic satellite network with the aim of minimizing the number of participant ground-based management stations and the cost of communication between satellites in the background of GNSS networking. Firstly, we assume the navigation constellation has finite states and cope the dynamic topology with Finite State Automation method. Secondly, a Fireworks algorithm (FWA) is designed according to the characteristic of the scheduling problem. Finally, the FWA is compared with ant colony optimization (ACO). The performance analysis of different scenarios is given. The study in this paper provides technical reference for the management of future large-scale satellite network. © 2016 IEEE.

关键词： Satellite links

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Reduction of Defects on Microstructure Aluminium Nitride Using High Temperature Annealing Heat Treatment

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IOP Conference Series: Materials Science and engineering 2018年第1期328卷

作者： Z Tanasta P Muhamad N Kuwano H M Y Norfazrina M H Unuh Intelligent Dynamics & System Research Lab Malaysia-Japan International Institute of Technology Universiti Teknologi Malaysia 54100 Kuala Lumpur Malaysia Nano-characterization Structural Control and Processing Malaysia-Japan International Institute of Technology Universiti Teknologi Malaysia 54100 Kuala Lumpur Malaysia Department of Mechanical Engineering Kulliyah of Engineering International Islamic University Malaysia 50728 Kuala Lumpur Malaysia

Aluminium Nitride (AlN) is a ceramic 111-nitride material that is used widely as components in functional devices. Besides good thermal conductivity, it also has a high band gap in emitting light which is 6 eV. AlN thin film is grown on the sapphire substrate (0001). However, lattice mismatch between both materials has caused defects to exist along the microstructure of AlN thin films. The defects have affected the properties of Aluminium Nitride. Annealing heat treatment has been proved by the previous researcher to be the best method to improve the microstructure of Aluminium Nitride thin films. Hence, this method is applied at four different temperatures for two hour. The changes of Aluminium Nitride microstructures before and after annealing is observed using Transmission Electron Microscope. It is observed that inversion domains start to occur at temperature of 1500 °C. Convergent Beam Electron Diffraction pattern simulation has confirmed the defects as inversion domain. Therefore, this paper is about to extract the matters occurred during the process of producing high quality Aluminium Nitride thin films and the ways to overcome this problem.

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Geometric path following control for multirotor vehicles using nonlinear model predictive control and 3D spline paths

Geometric path following control for multirotor vehicles usi...

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International Conference on Unmanned Aircraft systems (ICUAS)

作者： Philipp Niermeyer Venkata S. Akkinapalli Mikhail Pak Florian Holzapfel Boris Lohmann Department of Mechanical Engineering Institute of Automatic Control Garching Department of Mechanical Engineering Institute of Flight System Dynamics Garching

ISBN: (纸本)9781467393355

There is strong interest in Micro Aerial Vehicle (MAV) control architectures which are able to systematically respect physical limitations of the plant. Nonlinear Model Predictive control (NMPC) inherits the required constraint handling abilities and is easy to reconfigure in case of plant degradation. This work presents a promising cascaded control architecture for multirotors for the task to follow a geometric path. In contrast to existing NMPC implementations for path following, three times continuously differentiable reference trajectories are required due to the underactuated nature of multirotor vehicles. This is achieved by defining a path by a quartic spline and employ fourth order path dynamics. The proposed controller considers the dynamics of the inner acceleration loop explicitly so that the assumption of time-scale separation between the controller cascades can be dropped. The presented implementation allows for online adaptation of plant and control parameters as a first step towards application in a fault-tolerant setup. High fidelity simulation results demonstrate the favorable performance. Due to the observed runtimes well below a tenth of the sample rate, deployability to the onboard embedded computer can be expected.

关键词： Acceleration Vehicles Vehicle dynamics Predictive models Trajectory Actuators Degradation

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Enhancing flight control in case of total angle of attack sensor loss

Enhancing flight control in case of total angle of attack se...

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Conference on control and Fault-Tolerant systems (SysTol)

作者： Hans-Dieter Joos Daniel Ossmann Institute of System Dynamics and Control German Aerospace Center Germany Department of Aerospace Engineering & Mechanics University of Minnesota Minneapolis MN USA

ISBN: (纸本)9781509006595

To maintain nominal flight control system functionalities during fault scenarios, enhancements of the state-of-practice angle of attack fault accommodation strategies are presented. The enhancements rely on combining modern fault detection and diagnosis (FDD) techniques with a robust envelope protection algorithm. The FDD system is able to detect and isolate partial or total losses of angle of attack sensors. The angle of attack is not a directly controlled variable in the flight control system, but is used to protect the aircraft from exceeding the flight envelope. To avoid the state-of-practice degradation towards an unprotected control law in case of a total angle of attack sensor loss, longitudinal protection law functionalities independent of the lost measurements are proposed. They provide satisfactory prevention of reaching difficult flight conditions and can be operated together with the nominal command and stability augmentation system. This paper discusses the protection law design in conjunction with the sensor monitoring scheme and the nominal inner loop control law. The latest results of an extensive industrial validation and verification campaign are reported.

关键词： Aircraft control systems Loss measurement Aerospace control Monitoring Fault detection Degradation

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Fast search algorithm of high-precision earth-moon free-return trajectory

Fast search algorithm of high-precision earth-moon free-retu...

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AAS/AIAA Astrodynamics Specialist Conference, ASC 2015

作者： Peng, Kun Yim, Shingyik Zhang, Bainan Yang, Lei Guo, Linli Bu, Yanlong Zhang, Sihang Department of Engineering Institute of Manned Space System Engineering Chinese Academy of Space Technology Beijing100094 China School of Aerospace Engineering Tsinghua University Beijing100084 China National Key Laboratory on Aerospace Flight Dynamics Beijing Aerospace Control Center Beijing100094 China School of Astronautics Beihang University 37 Xueyuan Road Haidian District Beijing100191 China

ISBN: (纸本)9780877036296

Free-return trajectory design is an important guarantee for the safety of manned lunar mission. This trajectory can ensure that the spacecraft returns to Earth without any maneuver when the mission goes wrong. A fast search algorithm of high-precision Earth-Moon free-return trajectory is proposed in this paper. It is consisted of four parts: 1) solution model establishment for high-precision free-return trajectory, 2) initial values estimation for control variables, 3) multilevel search for free-return trajectory, 4) extended search for multiple types of free-return trajectory. This algorithm can search the accurate free-return trajectory without any designer-provided prior information, and can converge rapidly.

关键词： Learning algorithms

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Experimental evaluation of Linear Parameter-Varying semi-active suspension control

Experimental evaluation of Linear Parameter-Varying semi-act...

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IEEE Conference on control Technology and Applications (CCTA)

作者： Michael Fleps-Dezasse Mahmoud M. Ahmed Jonathan Brembeck Ferdinand Svaricek Institute of System Dynamics and Control (SR) German Aerospace Center (DLR) WeBling Germany Department of Aerospace Engineering University of the Federal Armed Forced Munich Neubiberg Germany

ISBN: (纸本)9781509007561

Semi-active suspensions offer a large potential to improve the trade-off between ride comfort and road-holding compared to passive suspensions. In order to exploit this potential, the suspension control approach should explicitly consider the force limits of the semi-active damper. For this purpose, a Linear Parameter Varying (LPV) plant with a saturation indicator and a saturation transformer parameter is developed. This plant model allows for the synthesis of an LPV controller with guaranteed closed-loop stability and performance. In experiments carried out on a quarter-vehicle test-rig, the performance of the LPV controller is compared to passive suspension configurations and a Skyhook/Groundhook (SH/GH) controller. The results show that the LPV controller achieves a better trade-off between ride comfort and road-holding together with a simultaneous reduction of the suspension motion.

关键词： Shock absorbers Force Actuators Circuit faults Roads Observers

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Decision-making for unmanned aerial vehicle operation in icing conditions

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CEAS Aeronautical Journal 2016年第4期7卷 663-675页

作者： Armanini, S.F. Polak, M. Gautrey, J.E. Lucas, A. Whidborne, J.F. Faculty of Aerospace Engineering Section Control and Simulation Delft University of Technology Kluyverweg 1 Delft2629HS Netherlands Institute of Flight System Dynamics Technische Universität München Boltzmannstraße 15 Garching85748 Germany National Flying Laboratory Centre School of Aerospace Transport and Manufacturing Cranfield University BedfordshireMK43 0AL United Kingdom Dynamics Simulation and Control Group School of Aerospace Transport and Manufacturing Cranfield University BedfordshireMK43 0AL United Kingdom AOS Group Ltd Sheraton House CB3 0AX CambridgeCastle Park United Kingdom

With the increased use of unmanned aerial systems (UAS) for civil and commercial applications, there is a strong demand for new regulations and technology that will eventually permit for the integration of UAS in unsegregated airspace. This requires new technology to ensure sufficient safety and a smooth integration process. The absence of a pilot on board a vehicle introduces new problems that do not arise in manned flight. One challenging and safety-critical issue is flight in known icing conditions. Whereas in manned flight, dealing with icing is left to the pilot and his appraisal of the situation at hand;in unmanned flight, this is no longer an option and new solutions are required. To address this, an icing-related decision-making system (IRDMS) is proposed. The system quantifies in-flight icing based on changes in aircraft performance and measurements of environmental properties, and evaluates what the effects on the aircraft are. Based on this, it determines whether the aircraft can proceed, and whether and which available icing protection systems should be activated. In this way, advice on an appropriate response is given to the operator on the ground, to ensure safe continuation of the flight and avoid possible accidents. © 2016, The Author(s).

关键词： Decision making

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Asteroid ryugu before the Hayabusa2 encounter

arXiv

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arXiv 2018年

作者： Wada, Koji Grott, Matthias Michel, Patrick Walsh, Kevin J. Barucci, Antonella M. Biele, Jens Blum, Jürgen Ernst, Carolyn M. Grundmann, Jan T. Gundlach, Bastian Hagermann, Axel Hamm, Maximilian Jutzi, Martin Kim, Myung-Jin Kührt, Ekkehard Le Corre, Lucille Libourel, Guy Lichtenheldt, Roy Maturilli, Alessandro Messenger, Scott R. Michikami, Tatsuhiro Miyamoto, Hideaki Mottola, Stefano Nakamura, Akiko M. Müller, Thomas Nittler, Larry R. Ogawa, Kazunori Okada, Tatsuaki Palomba, Ernesto Sakatani, Naoya Schröder, Stefan Takir, Driss Zolensky, Michael E. Tsudanuma 2-17-1 Narashino Chiba275-0016 Japan DLR Institute for Planetary Research Rutherfordstr. 2 Berlin12489 Germany Université Côte d'Azur Observatoire de la Côte d'Azur CNRS Lagrange Laboratory Southwest Research Institute Boulder United States Observatoire de Paris PSL Research University CNRS Université Paris Diderot Sorbonne Paris Cité UPMC Université Paris 06 Sorbonne Universités 5 Place J. Janssen Meudon Principal Cedex92195 France DLR RB-MSC German Aerospace Center Cologne51147 Germany Institut für Geophysik und extraterrestrische Physik Technische Universität Braunschweig Mendelssohnstr. 3 BraunschweigD-38106 Germany Johns Hopkins University Applied Physics Laboratory LaurelMD United States DLR German Aerospace Center Institute of Space Systems System Engineering and Project Office Robert-Hooke-Strasse 7 BremenD-28359 Germany Department of Biological and Environmental Sciences University of Stirling FK9 4LA United Kingdom Physics Institute University of Bern Switzerland Center for Space Situational Awareness Korea Astronomy and Space Science Institute 776 Daedeokdae-ro Yuseong-gu Daejeon305-348 Korea Republic of Planetary Science Institute 1700 East Fort Lowell Suite 106 TucsonAZ85719 United States DLR Institute of System Dynamics and Control Oberpfaffenhoffen Germany Robert M Walker for Space Sciences Astromaterials Research and Exploration Science NASA Johnson Space Center HoustonTX77058 United States Faculty of Engineering Kindai University Hiroshima Campus 1 Takaya Umenobe Higashi-Hiroshima Hiroshima739-2116 Japan Deptartment of Systems Innovation University of Tokyo Tokyo Japan Department of Planetology Graduate School of Science Kobe University 1-1 Rokkodai Nada-ku Kobe657-8501 Japan Max-Planck Institute for Extraterrestrial Physics Garching Germany Department of Terrestrial Magnetism Carnegie Institution of Washington 5241 Broad Branch Rd NW 20015 United States Institute of Space and Astronautical Sc

Asteroid (162173) Ryugu is the target object of Hayabusa2, an asteroid exploration and sample return mission led by Japan Aerospace Exploration Agency (JAXA). Ground-based observations indicate that Ryugu is a C-type near-Earth asteroid with a diameter of less than 1 km, but the knowledge of its detailed properties is still very limited. This paper summarizes our best understanding of the physical and dynamical properties of Ryugu based on remote sensing and theoretical modeling. This information is used to construct a design reference model of the asteroid that is used for formulation of mission operations plans in advance of asteroid arrival. Particular attention is given to the surface properties of Ryugu that are relevant to sample acquisition. This reference model helps readers to appropriately interpret the data that will be directly obtained by Hayabusa2 and promotes scientific studies not only for Ryugu itself and other small bodies but also for the Solar system evolution that small bodies shed light on. Copyright © 2018, The Authors. All rights reserved.

关键词： Asteroids

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