Discontinuous Dynamics and Bifurcation for Morphing Aircraft Switching on the Velocity Boundary

2020 ◽  
Author(s):  
Jianzhe Huang ◽  
Xilin Fu ◽  
Zhongliang Jing ◽  
Siyuan Xing
Keyword(s):  
High Speed ◽  
Critical Speed ◽  
Point Of View ◽  
Intermediate Structure ◽  
Morphing Aircraft ◽  
Low Speed ◽  
Stability And Control ◽  
System A ◽  
The Moment ◽  
And Control

Abstract The concept of morphing aircraft was developed many decades ago, and many researches on the morphing aircraft such as stability and control have been published. As the point of view of the dynamic theory, the dynamic system of the morphing aircraft is consisted with multiple subsystems, and each subsystem represents the morphing aircraft with specific structure to fulfill a particular flight task. The switching process from one structure to another for such a morphing aircraft is considered to be smooth and stable, and the switching time is also assumed to be infinitely small. In this paper, a morphing aircraft with high-speed structure, intermediate-structure and low-speed structure is studied. Such a morphing aircraft is set to switch between high-speed structure and low-speed structure when the speed of aircraft arrives a preset critical speed, and the analytical conditions for switchability is developed. If such a morphing aircraft cannot switch to a low-speed structure or high-speed structure at the moment when it arrives the critical speed, it will switch to an intermediate-structure and control to keep the speed remain constant. The analytical conditions for onset and vanish of such a morphing aircraft switching to the intermediate-structure are also provided. Mapping structure is defined to describe the periodic motions of such a morphing aircraft. The bifurcation scenario is calculated to show the complexity of such a hybrid dynamical system. A periodic motion is given to illustrate the flow of such a morphing aircraft switching on the velocity boundary.

Stability and control of high-speed flows

2001 ◽  
Author(s):  
Helen Reed ◽  
William Saric ◽  
Ian Lyttle ◽  
Yasutoshi Asada
Keyword(s):  
High Speed ◽  
Stability And Control ◽  
And Control ◽  
High Speed Flows

THE DYNAMICS OF SYSTEMS OF COMPLEX NONLINEAR OSCILLATORS: A REVIEW

2004 ◽  
Vol 14 (11) ◽  
pp. 3821-3846 ◽  
Author(s):  
GAMAL M. MAHMOUD ◽  
TASSOS BOUNTIS
Keyword(s):  
Phase Space ◽  
Periodic Solutions ◽  
Chaotic Behavior ◽  
Nonlinear Oscillators ◽  
Complex Variables ◽  
Point Of View ◽  
Stability And Control ◽  
Ginzburg Landau Equations ◽  
The Stability ◽  
And Control

Dynamical systems in the real domain are currently one of the most popular areas of scientific study. A wealth of new phenomena of bifurcations and chaos has been discovered concerning the dynamics of nonlinear systems in real phase space. There is, however, a wide variety of physical problems, which, from a mathematical point of view, can be more conveniently studied using complex variables. The main advantage of introducing complex variables is the reduction of phase space dimensions by a half. In this survey, we shall focus on such classes of autonomous, parametrically excited and modulated systems of complex nonlinear oscillators. We first describe appropriate perturbation approaches, which have been specially adapted to study periodic solutions, their stability and control. The stability analysis of these fundamental periodic solutions, though local by itself, can yield considerable information about more global properties of the dynamics, since it is in the vicinity of such solutions that the largest regions of regular or chaotic motion are observed, depending on whether the periodic solution is, respectively, stable or unstable. We then summarize some recent studies on fixed points, periodic solutions, strange attractors, chaotic behavior and the problem of chaos control in systems of complex oscillators. Some important applications in physics, mechanics and engineering are mentioned. The connection with a class of complex partial differential equations, which contains such famous examples, as the nonlinear Schrödinger and Ginzburg–Landau equations is also discussed. These complex equations play an important role in many branches of physics, e.g. fluids, superconductors, plasma physics, geophysical fluids, modulated optical waves and electromagnetic fields.

Paper 26. Stability and Control in Waves: A Survey of the Problem

1972 ◽  
Vol 14 (7) ◽  
pp. 186-193 ◽  
Author(s):  
J. E. Conolly
Keyword(s):  
Mathematical Models ◽  
Orbital Motion ◽  
Model Tests ◽  
Point Of View ◽  
Stability And Control ◽  
Free Running ◽  
And Control

Manoeuvrability in waves is discussed from the point of view of the dangers of broaching-to when a ship is running before the sea. Conditions are assessed under which this may occur, illustrated by documented cases, including the Wahine disaster in 1968. Because of the problems involved in investigating broaching-to by means of free-running model tests, there is an urgent need for reliable mathematical models: however, theories published so far, based on two different simplifications, are shown to have limitations. It is argued that the theory must take account of pitching, surging, rolling and orbital motion of the water particles.

The Design of High Speed LVDS Parallel Port Communication Protocol

2015 ◽  
Vol 740 ◽  
pp. 852-856
Author(s):  
Lei Zheng ◽  
Chen Xi Yang ◽  
Jia Kang Liu
Keyword(s):  
High Speed ◽  
Low Voltage ◽  
Gigabit Ethernet ◽  
System A ◽  
Double Edge ◽  
Differential Signaling ◽  
Point To Point ◽  
Edge Sampling ◽  
Electrical Connections ◽  
And Control

In the image display and control system, a high speed dissymmetrical point to point communication port and protocol between GENIC(Gigabit Ethernet Network Interface Card) and SDRAM based on LVDS (Low Voltage Differential signaling) and STOP-WAIT ARQ protocol are designed, while the port’s speed should not below 1Gbps. Five lines LVDS signal pairs are used in one direction, including one clock and four data in the port’s electrical connections. Double-edge sampling and source synchronizing are also used. Mode 256 checkout is used to guarantee the reliable data transmission. Analysis shows that the port’s bandwidth is 1.2Gbps, the efficiency of protocol is above 99% and the protocol works steadily and reliably.

Measurements in High Void-Fraction Bubbly Wakes Created by Ventilated Supercavitation

2005 ◽  
Author(s):  
Martin Wosnik ◽  
Lucas Gomez Fontecha ◽  
Roger E. A. Arndt
Keyword(s):  
Void Fraction ◽  
High Speed ◽  
Bubble Velocity ◽  
Time Resolved ◽  
Stability And Control ◽  
Ventilated Supercavity ◽  
High Reynolds ◽  
Similarity Scaling ◽  
Interdisciplinary Study ◽  
And Control

A detailed study of ventilated supercavitation in the reentrant jet regime is being carried out in the high-speed water tunnel at St. Anthony Falls Laboratory, as the hydrodynamics part of an interdisciplinary study on stability and control of high-speed cavity-running bodies. It is aimed at understanding the interaction between a ventilated supercavity and its turbulent bubbly wake, with the goal to provide the information needed for the development of control algorithms. Here Particle Image Velocimetry (PIV) measurements in high void fraction bubbly wakes created by the collapse of ventilated supercavities are reported. Bubble velocity fields are obtained, and shown to submit to the same high Reynolds number similarity scaling as the single-phase turbulent axisymmetric wake. A grayscale technique to measure local average void fraction is outlined. Initial results of a time-resolved PIV experiment (2000 Hz) are also presented.

Spinning gasodynamic projectile system identification experiment design

2020 ◽  
Vol 92 (3) ◽  
pp. 452-459 ◽  
Author(s):  
Piotr Lichota ◽  
Mariusz Jacewicz ◽  
Joanna Szulczyk
Keyword(s):  
System Identification ◽  
High Speed ◽  
Content Type ◽  
Stability And Control ◽  
Novel Approach ◽  
Control Derivatives ◽  
Designed Experiment ◽  
Regions Of Stability ◽  
Short Time ◽  
And Control

Purpose The purpose of this paper is to present the methodology that was used to design a system identification experiment of a generic spinning gasodynamic projectile. For this object, because the high-speed spinning motion, it was not possible to excite the aircraft motion along body axes independently. Moreover, it was not possible to apply simultaneous multi-axes excitations because of the short time in which system identification experiments can be performed (multi-step inputs) or because it is not possible to excite the aircraft with a complex input (multi-sine signals) because of the impulse gasodynamic engines (lateral thrusters) usage. Design/methodology/approach A linear projectile model was used to obtain information about identifiability regions of stability and control derivatives. On this basis various sets of lateral thrusters’ launching sequences, imitating continuous multi-step inputs were used to excite the nonlinear projectile model. Subsequently, the nonlinear model for each excitation set was identified from frequency responses, and the results were assessed. For comparison, the same approach was used for the same projectile exited with aerodynamic controls. Findings It was found possible to design launching sequences of lateral thrusters that imitate continuous multi-step input and allow to obtain accurate system identification results in specified frequency range. Practical implications The designed experiment can be used during polygonal shooting to obtain a true projectile aerodynamic model. Originality/value The paper proposes a novel approach to gasodynamic projectiles system identification and can be easily applied for similar cases.

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