scholarly journals An analysis of instabilities and limit cycles in glacier-dammed reservoirs

2019 ◽  
Author(s):  
Christian Schoof
Keyword(s):  
Limit Cycle ◽  
Limit Cycles ◽  
Water Storage ◽  
Drainage System ◽  
Stable Limit Cycle ◽  
Stable Limit ◽  
Outburst Floods ◽  
The World ◽  
The Stability ◽  
Glacial Hazards

Abstract. Glacier lake outburst floods are common glacial hazards around the world. How big such floods can become (either in terms of peak discharge or in terms of total volume released) depends on how they are initiated: what causes the runaway enlargement of a subglacial or other conduit to start, and how big can the lake get before that point is reached? Here we investigate how the spontaneous channelization of a linked-cavity drainage system controls the onset of floods. In agreement with previous work, we show that floods only occur in a band of water throughput rates, and identify stabilizing mechanisms that allow steady drainage of an ice-dammed reservoir. We also show how stable limit cycle solutions emerge from the instability, a show how and why the stability properties of a drainage system with spatially spread-out water storage differ from those where storage is localized in a single reservoir or lake.

scholarly journals An analysis of instabilities and limit cycles in glacier-dammed reservoirs

2020 ◽  
Vol 14 (9) ◽  
pp. 3175-3194
Author(s):  
Christian Schoof
Keyword(s):  
Limit Cycle ◽  
Limit Cycles ◽  
Drainage System ◽  
Stable Limit Cycle ◽  
Peak Discharge ◽  
Stable Limit ◽  
Outburst Floods ◽  
The World ◽  
Glacial Hazards

Abstract. Glacier lake outburst floods are common glacial hazards around the world. How big such floods can become (either in terms of peak discharge or in terms of total volume released) depends on how they are initiated: what causes the runaway enlargement of a subglacial or other conduit to start the flood, and how big can the lake get before that point is reached? Here we investigate how the spontaneous channelization of a linked-cavity drainage system can control the onset of floods. In agreement with previous work, we show that floods only occur in a band of water throughput rates in which steady reservoir drainage is unstable, and we identify stabilizing mechanisms that allow steady drainage of an ice-dammed reservoir. We also show how stable limit cycle solutions emerge from the instability and identify parameter regimes in which the resulting floods cause flotation of the ice dam. These floods are likely to be initiated by flotation rather than the unstable enlargement of a distributed drainage system.

scholarly journals STUDYING THE STABILITY BY USING LOCAL LINEARIZATION METHOD

2020 ◽  
Vol 2 (1) ◽  
pp. 27-31
Author(s):  
Abdulghafoor Jasim Salim ◽  
Kais Ismail Ebrahem ◽  
Suhirman
Keyword(s):  
Singular Point ◽  
Limit Cycle ◽  
Autoregressive Model ◽  
Stable Limit Cycle ◽  
Linearization Method ◽  
Stable Limit ◽  
Local Linearization ◽  
Non Linear ◽  
The Stability ◽  
Local Linearization Method

Abstract: In this paper we study the stability of one of a non linear autoregressive model with trigonometric term  by using local linearization method proposed by Tuhro Ozaki .We find the singular point ,the stability of the singular point and the limit cycle. We conclude  that the proposed model under certain conditions have a non-zero singular point which is  a asymptotically salable ( when  0 ) and have an  orbitaly stable limit cycle . Also we give some examples in order to explain the method. Key Words : Non-linear Autoregressive model; Limit cycle; singular point; Stability.

Energy harvesting for actuators and sensors using free-floating flaps

2016 ◽  
Vol 28 (2) ◽  
pp. 163-177 ◽  
Author(s):  
Lars O Bernhammer ◽  
Roeland De Breuker ◽  
Moti Karpel
Keyword(s):  
Limit Cycle ◽  
Vibrational Energy ◽  
Stable Limit Cycle ◽  
Electric Circuit ◽  
Electronic System ◽  
Rotational Axis ◽  
Stable Limit ◽  
Limit Cycle Oscillations ◽  
Trailing Edge ◽  
The Stability

A novel configuration of an energy harvester for local actuation and sensing devices using limit cycle oscillations has been modeled, designed and tested. A wing section has been designed with two trailing-edge free-floating flaps. A free-floating flap is a flap that can freely rotate around a hinge axis and is driven by trailing edge tabs. In the rotational axis of each flap a generator is mounted that converts the vibrational energy into electricity. It has been demonstrated numerically how a simple electronic system can be used to keep such a system at stable limit cycle oscillations by varying the resistance in the electric circuit. Additionally, it was shown that the stability of the system is coupled to the charge level of the battery, with increasing charge level leading to a less stable system. The system has been manufactured and tested in the Open Jet Wind Tunnel Facility of the Technical University Delft. The numerical results could be validated successfully and voltage generation could be demonstrated at cost of a decrease in lift of 2%.

The Multiple Contributions of Jorgen Lund’s Ph.D. Dissertation, “Self-Excited, Stationary Whirl Orbits of a Journal in Sleeve Bearings,” RPI, 1966, Engineering Mechanics

2001 ◽  
Author(s):  
Dara W. Childs
Keyword(s):  
Limit Cycle ◽  
Limit Cycles ◽  
Stable Limit Cycle ◽  
Stable Limit ◽  
Rigid Rotor ◽  
Engineering Mechanics ◽  
Stable Limit Cycles

Abstract Lund set out to define the circumstances under which stable limit-cycle orbits could exist for the linearly unstable motion of a rigid rotor. He also undertook to examine the nature of these stable limit cycles when they are demonstrated to exist. He obviously succeeded in meeting both these objectives; however, Lund’s really remarkable and most useful contributions are covered “incidentally” in the course of developing his nonlinear analytical/computational solutions.

Inducing sustained oscillations in a class of nonlinear discrete time systems

2016 ◽  
Vol 24 (6) ◽  
pp. 1162-1170 ◽  
Author(s):  
AR Hakimi ◽  
T Binazadeh
Keyword(s):  
Limit Cycle ◽  
Discrete Time ◽  
Stable Limit Cycle ◽  
Domain Of Attraction ◽  
Stable Limit ◽  
Discrete Time System ◽  
Sustained Oscillations ◽  
Discrete Time Systems ◽  
The Stability ◽  
Time Systems

Inducing sustained oscillations in a class of nonlinear discrete time systems is studied in this paper. The novelty of this paper is based on the proposed approach in generating stable oscillations according to limit cycle control. The limit cycle control is not formulated for nonlinear discrete time systems of any order and this paper concentrates on this issue. Considering the stable limit cycle as a positive limit set for the dynamical system, a nonlinear control law is designed to create the considered limit cycle in the phase trajectories of the closed-loop nonlinear discrete time system to achieve oscillations with the desirable amplitude and frequency. For this purpose, firstly, the limit cycle control is proposed for second-order nonlinear discrete time systems. The stability analysis of the generated limit cycle is done via a suitable Lyapunov function. Also, the domain of attraction of the created limit cycle is calculated. The proposed method is then extended for nonlinear discrete time systems of any order via the backstepping technique. Finally, computer simulations are performed for a practical example to demonstrate the ability of the designed controller in generating stable oscillations.

scholarly journals STUDY POINTS OF REST HEREDITARITY DYNAMIC SYSTEMS VAN DER POL-DUFFING

2019 ◽  
pp. 71-77
Author(s):  
Е.Р. Новикова ◽  
Р.И. Паровик
Keyword(s):  
Limit Cycle ◽  
Dynamic Systems ◽  
Limit Cycles ◽  
Stable Limit Cycle ◽  
Viscous Friction ◽  
Oscillatory System ◽  
Stable Limit ◽  
Van Der Pol ◽  
Nonlinear Oscillatory System ◽  
Stable Limit Cycles

Using numerical modeling, oscillograms and phase trajectories were constructed to study the limit cycles of a van der Pol Duffing nonlinear oscillatory system with a power memory. The simulation results showed that in the absence of a power memory (α = 2, β = 1) or the classical van der Pol Duffing dynamical system, there is a single stable limit cycle, i.e. Lienar theorem holds. In the case of viscous friction (α = 2, 0 < β < 1), there is a family of stable limit cycles of various shapes. In other cases, the limit cycle is destroyed in two scenarios: a Hopf bifurcation (limit cycle-limit point) or (limit cycle-aperiodic process). Further continuation of the research may be related to the construction of the spectrum of Lyapunov maximal exponents in order to identify chaotic oscillatory regimes for the considered hereditary dynamic system (HDS). В работе с помощью численного моделирования построены осциллограммы и фазовые траектории с целью исследования предельных циклов нелинейной колебательной системы Ван-дер-Поля Дуффинга со степенной памятью. Результаты моделирования показали, что в случае отсутствия степенной памяти (α = 2, β = 1) или классической динамической системы Ван-дер-Поля Дуффинга, существует единственный устойчивый предельный цикл, т.е. выполняется теорема Льенара. В случае вязкого трения (α = 2, 0 < β < 1), существует семейство устойчивых предельных циклов различной формы. В остальных случаях происходит разрушение предельного цикла по двум сценариям: бифуркация Хопфа (предельный цикл-предельная точка) или (предельный циклапериодический процесс). Дальнейшее продолжение исследований может быть связано с построением спектра максимальных показателей Ляпунова с целью идентификации хаотических колебательных режимов для рассматриваемой эредитарной динамической системы (ЭДС).

Sensitivity Enhancement of Cantilever-Based Sensors Using Feedback Delays

2010 ◽  
Vol 5 (4) ◽  
Author(s):  
Calvin Bradley ◽  
Mohammed F. Daqaq ◽  
Amin Bibo ◽  
Nader Jalili
Keyword(s):  
Limit Cycle ◽  
Limit Cycles ◽  
Stable Limit Cycle ◽  
Sensitivity Enhancement ◽  
Design Parameters ◽  
Feedback Signal ◽  
Stable Limit ◽  
Theoretical Understanding ◽  
Cycle Amplitude ◽  
Limit Cycle Amplitude

This paper entails a novel sensitivity-enhancement mechanism for cantilever-based sensors. The enhancement scheme is based on exciting the sensor at the clamped end using a delayed-feedback signal obtained by measuring the tip deflection of the sensor. The gain and delay of the feedback signal are chosen such that the base excitations set the beam into stable limit-cycle oscillations as a result of a supercritical Hopf bifurcation of the trivial fixed points. The amplitude of these limit-cycles is shown to be ultrasensitive to parameter variations and, hence, can be utilized for the detection of minute changes in the resonant frequency of the sensor. The first part of the manuscript delves into the theoretical understanding of the proposed mechanism and the operation concept. Using the method of multiple scales, an approximate analytical solution for the steady-state limit-cycle amplitude near the stability boundaries is obtained. This solution is then utilized to provide a comprehensive understanding of the effect of small frequency variations on the limit-cycle amplitude and the sensitivity of these limit-cycles to different design parameters. Once a deep theoretical understanding is established, the manuscript provides an experimental study to investigate the proposed concept. Experimental results demonstrate orders of magnitude sensitivity enhancement over the traditional frequency-shift method.

Robust Generation of Limit Cycles in Nonlinear Systems: Application on Two Mechanical Systems

2017 ◽  
Vol 12 (4) ◽  
Author(s):  
Ali Reza Hakimi ◽  
Tahereh Binazadeh
Keyword(s):  
Nonlinear Systems ◽  
Limit Cycle ◽  
Limit Cycles ◽  
Closed Loop ◽  
Stable Limit Cycle ◽  
Additional Term ◽  
Loop System ◽  
Stable Limit ◽  
Closed Loop System ◽  
Robust Performance

This paper studies inducing robust stable oscillations in nonlinear systems of any order. This goal is achieved through creating stable limit cycles in the closed-loop system. For this purpose, the Lyapunov stability theorem which is suitable for stability analysis of the limit cycles is used. In this approach, the Lyapunov function candidate should have zero value for all the points of the limit cycle and be positive in the other points in the vicinity of it. The proposed robust controller consists of a nominal control law with an additional term that guarantees the robust performance. It is proved that the designed controller results in creating the desirable stable limit cycle in the phase trajectories of the uncertain closed-loop system and leads to induce stable oscillations in the system's output. Additionally, in order to show the applicability of the proposed method, it is applied on two practical systems: a time-periodic microelectromechanical system (MEMS) with parametric errors and a single-link flexible joint robot in the presence of external disturbances. Computer simulations show the effective robust performance of the proposed controllers in generating the robust output oscillations.

Multiple Limit Cycles in Laser Interference Transduced Resonators

2011 ◽  
Author(s):  
David B. Blocher ◽  
Richard H. Rand ◽  
Alan T. Zehnder
Keyword(s):  
Limit Cycle ◽  
Limit Cycles ◽  
Thermal Stresses ◽  
Stable Limit Cycle ◽  
Laser Interferometry ◽  
Numerical Continuation ◽  
Stable Limit ◽  
Laser Interference ◽  
Direct Numerical Integration ◽  
Stable Limit Cycles

Nanoscale resonators whose motion is measured through laser interferometry are known to exhibit stable limit cycle motion. Motion of the resonator through the interference field modulates the amount of light absorbed by the resonator and hence the temperature field within it. The resulting coupling of motion and thermal stresses can lead to self oscillation, i.e. a limit cycle. In this work the coexistence of multiple stable limit cycles is demonstrated in an analytic model. Numerical continuation and direct numerical integration are used to study the structure of the solutions to the model. The effect of damping is discussed as well as the properties that would be necessary for physical devices to exhibit this behavior.

An Analysis of Micro Aeroelastic Energy Harvesting Devices

2009 ◽  
Author(s):  
Daniel G. Cole ◽  
Lisa M. Weiland
Keyword(s):  
Power Generation ◽  
Renewable Energy ◽  
Energy Harvesting ◽  
Limit Cycle ◽  
Stable Limit Cycle ◽  
Stable Limit ◽  
Energy Harvesters ◽  
The Stability ◽  
Energy Harvesting Devices ◽  
Multi Mode

New micro renewable energy harvesting devices are being developed using the stable limit cycle response of aeroelastic systems to drive energy conversion. This paper analyzes such devices. This paper investigates devices that use two types of aeroelastic instability: galloping and multi-mode flutter. Since the generation of power can be stabilizing, resulting in no power generation at all, the analysis begins by analyzing the stability of such devices from the perspective of power generation. Next, the level of power generation is discussed, and peak levels of performance are found. The analysis suggests that with proper tuning the power generation of micro aeroelastic energy harvesters operating at representative speeds (∼4.5 m/s (10 mph)) can produce power on the order of 10 mW.

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