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Journal articles on the topic 'Flutter'

To see the other types of publications on this topic, follow the link: Flutter.

Author: Grafiati

Published: 4 June 2021

Last updated: 6 September 2023

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1

Xing, Tong, and Liang Fu. "A Study of a Miniature Modularized Electro-Hydraulic High-Frequency Flutter." Applied Mechanics and Materials 201-202 (October 2012): 360–63. http://dx.doi.org/10.4028/www.scientific.net/amm.201-202.360.

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In order to solve the problem that traditional flutters can’t reach the requirements of vibration-assisted machining (VAM), a miniature modularized electro-hydraulic high-frequency flutter was proposed, which can output large force in high frequency. The structure and working principle of the flutter were elaborated in this paper. The equations of the valve in this flutter can be obtained based on equations of tradition valves, which established the mathematical model of the flutter. The flutter output waveforms were analysed by MATLAB in different input frequencies. The simulation results show that the flutter amplitude reach the maximum value in resonant frequency.

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2

GUO, TONGQING, ZHILIANG LU, and YONGJIAN WU. "A TIME-DOMAIN METHOD FOR TRANSONIC FLUTTER ANALYSIS WITH MULTIDIRECTIONAL COUPLED VIBRATIONS." Modern Physics Letters B 23, no. 03 (January 30, 2009): 453–56. http://dx.doi.org/10.1142/s0217984909018631.

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Gridgen is employed for static multi-block grid generation. A rapid deforming technique is employed for dynamic grids. Flutters are numerically analyzed in the time domain with a coupled solution of unsteady Euler equations and structural equations of motion. Based on variable stiffness method of transonic flutter analysis, a time-domain method of transonic flutter analysis with multi-directional coupled vibrations is develpoed. For completeness, flutter characteristics of a wing model with winglets and an aircraft model with external stores are numerically analyzed.

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3

Weber LeBrun, Emily E. "Flutter, Flutter." Obstetrics & Gynecology 127, no. 2 (February 2016): 400. http://dx.doi.org/10.1097/aog.0000000000001249.

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4

Cavallaro, Joseph, James Haran, and Chase Donaldson. "All That Flutters is Not Flutter." Annals of Emergency Medicine 76, no. 1 (July 2020): 46–49. http://dx.doi.org/10.1016/j.annemergmed.2019.12.013.

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5

Kurkov, A. P., and O. Mehmed. "Optical Measurements of Unducted Fan Flutter." Journal of Turbomachinery 115, no. 1 (January 1, 1993): 189–96. http://dx.doi.org/10.1115/1.2929206.

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The paper describes a nonintrusive optical method for measuring flutter vibrations in unducted fan or propeller rotors and provides detailed spectral results for two flutter modes of a scaled unducted fan. The measurements were obtained in a high-speed wind tunnel. A single-rotor and a dual-rotor counterrotating configuration of the model were tested; however, only the forward rotor of the counterrotating configuration fluttered. Conventional strain gages were used to obtain flutter frequency; optical data provided complete phase results and an indication of the flutter mode shape through the ratio of the leading- to trailing-edge flutter amplitudes near the blade tip. In the transonic regime the flutter exhibited some features that are usually associated with nonlinear vibrations. Experimental mode shape and frequencies were compared with calculated values that included centrifugal effects.

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6

Mayell, Marcus R., Nicolaus T. Dulworth, Brandon Cudequest, and Robin Glosemeyer Petrone. "One acoustician’s defect is another artist’s feature: Simulating real flutter for an art installation." Journal of the Acoustical Society of America 152, no. 4 (October 2022): A210. http://dx.doi.org/10.1121/10.0016034.

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Flutter is generally considered an acoustical defect – the timbral distortions and rhythmic nature can be distracting, annoying, or downright disruptive. The paper recontextualizes flutter as a compositional tool for sound art, particularly when the flutter of existing rooms is used for site-specific installations. Due to the global COVID-19 pandemic, the artist was unable to travel, allowing us to visit the site and take several room impulse responses. The measured spaces were parallelpiped, sound reflective, and fluttery. To give the artist creative flexibility, we simulated the rooms for an extended range of source and receiver locations informed by the in-situ measurements. This paper will discuss our calibration and modeling techniques to simulate flutter and reverberation coloration in real rooms, which is non-trivial for image source methods or ray-based software.

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7

Raut, Roshan, Prashanta Bajracharya, Man Bahadur KC, Murari Dhungana, Mukunda Sharma, Surakshya Joshi, Prashanta Bajracharya, Kunjang Sherpa, Mandita Chamlagain, and Sujeeb Rajbhandari. "Efficacy and Safety of Focal Atrial Tachycardia and Typical Atrial Flutter Ablation in Nepal-A Single Center Experience." Nepalese Heart Journal 18, no. 1 (April 30, 2021): 25–28. http://dx.doi.org/10.3126/njh.v18i1.36776.

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Background and Aims: Atrial tachycardia is classified as focal atrial tachycardia or macro-reentrant atrial tachycardia. Macro-reentrant atrial tachycardia involves large circuit and is also called atrial flutter in which cavotricuspid isthmus dependent flutter, also called typical atrial flutter is the most common. The aim of this study is to report the efficacy and safety of catheter ablations of these arrhythmias, for the first time in Nepal. Methods: This is a retrospective observational study of the patients who underwent electrophysiological study with ablation for focal atrial tachycardia and typical atrial flutters at Shahid Gangalal National Heart Center (SGNHC) from March, 2015 to February 2020. Results: Altogether, 49 patients, 27 for focal atrial tachycardia and 22 for typical atrial flutter, underwent electrophysiology study with intent to ablation. In two patients, atrial tachycardia could not be induced, therefore 25 patients underwent ablation for atrial tachycardia. Out of 25 patients, the successful ablation achieved in 24 patients (96%) with recurrence in three patients (12%), with no major complications. Atrial tachycardia more commonly originated from right atrium than the left atrium (68% vs. 32%). Among 22 patients who underwent cavotricuspid isthmus ablation for typical atrial flutter; successful ablation achieved in 21 patients (95%) with recurrence in two patients (9%) and a single case of access site hematoma. Counterclockwise flutter was found to be more common than clockwise flutter (91% vs. 9%). Conclusion: In SGNHC, the ablations of focal atrial tachycardia and the typical atrial flutter has a high success and low complication rate.

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8

Byun, Junghwan, Minjo Park, Sang-Min Baek, Jaeyoung Yoon, Woongbae Kim, Byeongmoon Lee, Yongtaek Hong, and Kyu-Jin Cho. "Underwater maneuvering of robotic sheets through buoyancy-mediated active flutter." Science Robotics 6, no. 53 (April 21, 2021): eabe0637. http://dx.doi.org/10.1126/scirobotics.abe0637.

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Falling leaves flutter from side to side due to passive and intrinsic fluid-body coupling. Exploiting the dynamics of passive fluttering could lead to fresh perspectives for the locomotion and manipulation of thin, planar objects in fluid environments. Here, we show that the time-varying density distribution within a thin, planar body effectively elicits minimal momentum control to reorient the principal flutter axis and propel itself via directional fluttery motions. We validated the principle by developing a swimming leaf with a soft skin that can modulate local buoyancy distributions for active flutter dynamics. To show generality and field applicability, we demonstrated underwater maneuvering and manipulation of adhesive and oil-skimming sheets for environmental remediation. These findings could inspire future intelligent underwater robots and manipulation schemes.

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9

Nolan, Nathanial S., Scott M. Koerber, and Sudarshan Balla. "Pseudoatrial Flutter Waves—When a Flutter Is Not a Flutter." JAMA Internal Medicine 176, no. 3 (March 1, 2016): 298. http://dx.doi.org/10.1001/jamainternmed.2015.8315.

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10

Matsumoto, M., F. Yoshizumi, T. Yabutani, K. Abe, and N. Nakajima. "Flutter stabilization and heaving-branch flutter." Journal of Wind Engineering and Industrial Aerodynamics 83, no. 1-3 (November 1999): 289–99. http://dx.doi.org/10.1016/s0167-6105(99)00079-3.

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11

Liu, Ying, Xiaobo Zhang, and Fei Zhang. "Simulation of flutter suppression for a transonic fan blade based on plasma excitation." MATEC Web of Conferences 355 (2022): 01018. http://dx.doi.org/10.1051/matecconf/202235501018.

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Along with the development of advanced high-performance aero-engines to the higher thrust-weight ratio, further improvement of stage load, the adoption of new materials and new lightweight structures, the aeroelasticity of blade structure is becoming more and more prominent. The high cycle fatigue failure of blades significantly reduces the structural reliability during the process of development and using. At the same time, a large number of failure forms of aero-engine experimental and server can be attributed to aeroelastic problems. Therefore, it is urgent to improve the aeroelastic stability of the blade. One of the most important factors is to suppress the airflow separation, but its mechanism is still unclear. Based on this, this paper combines the aerodynamic damping analysis of energy method with the plasma excitation simulation and references low-speed wind tunnel plasma expansion test to consider the effects of different exciter distributions and intensities on flutter. The results show that stall flutter is related to the flow separation, but the flow separation is not a key factor that determinates whether the flutters occurs or not. Flutter suppression is strongly correlated with the shock wave intensity, amplitude of first harmonic aerodynamic force, low-speed separation and aerodynamic work density. In addition, the relative distribution of the excitation field and the positive work zone also has a direct effect on the suppression of flutter.

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12

Roizner, Federico, Daniella E. Raveh, and Moti Karpel. "Safe Flutter Tests Using Parametric Flutter Margins." Journal of Aircraft 56, no. 1 (January 2019): 228–38. http://dx.doi.org/10.2514/1.c035045.

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13

Dimitriadis, G., and J. E. Cooper. "Flutter Prediction from Flight Flutter Test Data." Journal of Aircraft 38, no. 2 (March 2001): 355–67. http://dx.doi.org/10.2514/2.2770.

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14

Tanaka, H., N. Yamamura, and M. Tatsumi. "Coupled mode flutter analysis using flutter derivatives." Journal of Wind Engineering and Industrial Aerodynamics 42, no. 1-3 (October 1992): 1279–90. http://dx.doi.org/10.1016/0167-6105(92)90135-w.

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15

Zhang, Xin, and Lin Zhao. "Limitations of the flutter derivative model." Advances in Structural Engineering 22, no. 6 (December 1, 2018): 1399–411. http://dx.doi.org/10.1177/1369433218814025.

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Flutter derivatives identified from transient (free-decay) vibrations might not be suitable for the analysis of bridge flutter. The application of transient flutter derivatives in the flutter analysis relies on two assumptions: (1) transient flutter derivatives and steady-state flutter derivatives are equivalent and (2) aeroelastic effects are superposable. Both assumptions are challenged in this article. It is shown through transient vibration tests that (1) the aeroelastic-coupling between heaving and rotational motions may switch from one pattern to another as the wind speed varies and (2) some of the transient flutter derivatives may be time-varying. The former implies that the predicted flutter type based on transient flutter derivatives may not be unconditionally consistent with the experimentally observed flutter type; the latter implies the transient flutter derivatives may be physically different from the steady-state flutter derivatives. These two issues undermine the basic assumptions of the flutter analysis of bridges. A possible corollary to this study is that if free vibration is used to predict bridge flutter, we should resort to the steady-state (flutter state) vibration instead of the transient vibration of the sectional model. A revision to the aeroelastic force model is proposed to facilitate the discussion.

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16

Bai, Hua, Wei Guo, Wei Li, and Yu Li. "Research on the Influence of the Aerodynamic Measure on the Flutter Derivative of the Steel Truss Suspension Bridge." Advanced Materials Research 532-533 (June 2012): 252–56. http://dx.doi.org/10.4028/www.scientific.net/amr.532-533.252.

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Flutter derivative is a significant index of the structure flutter stability. Identifying flutter derivative precisely contributes to the bridge flutter stability analyzing. In this paper, we take a research on the Liujiaxia Bridge in Gansu Province, China. Different flutter derivatives, which were got via segment model vibration tests with different aerodynamic measures, were classified, and made comparison in order to get the law of how different aerodynamic measures effect on the flutter derivative. The results show that, setting central stabilized plate, Build-in deflector, flange plate all affect flutter derivative significantly, which leads to changes in the flutter critical wind velocity of the structure. Setting central stabilized plate above the deck contributes to identify the flutter derivative of the 0° and positive attack angle, while setting central stabilized plate will contribute to flutter derivative identification at negative angles. It will make it difficult to identify the flutter derivative at 0° and -3° if the built-in deflector was set. Wind plate contributes to the identification of the flutter derivative at +3°, however, it will make it harder to identify the flutter derivative at 0° and -3°.

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17

Li, Nailu, Mark J. Balas, Pourya Nikoueeyan, Hua Yang, and Jonathan W. Naughton. "Stall Flutter Control of a Smart Blade Section Undergoing Asymmetric Limit Oscillations." Shock and Vibration 2016 (2016): 1–14. http://dx.doi.org/10.1155/2016/5096128.

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Stall flutter is an aeroelastic phenomenon resulting in unwanted oscillatory loads on the blade, such as wind turbine blade, helicopter rotor blade, and other flexible wing blades. Although the stall flutter and related aeroelastic control have been studied theoretically and experimentally, microtab control of asymmetric limit cycle oscillations (LCOs) in stall flutter cases has not been generally investigated. This paper presents an aeroservoelastic model to study the microtab control of the blade section undergoing moderate stall flutter and deep stall flutter separately. The effects of different dynamic stall conditions and the consequent asymmetric LCOs for both stall cases are simulated and analyzed. Then, for the design of the stall flutter controller, the potential sensor signal for the stall flutter, the microtab control capability of the stall flutter, and the control algorithm for the stall flutter are studied. The improvement and the superiority of the proposed adaptive stall flutter controller are shown by comparison with a simple stall flutter controller.

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18

Wang, Hao, Jiao Jiao Ding, Bing Ma, and Shuai Bin Li. "The Time Domain Analysis of the Flutter of Wind Turbine Blade Combined with Eigenvalue Approach." Advanced Materials Research 860-863 (December 2013): 342–47. http://dx.doi.org/10.4028/www.scientific.net/amr.860-863.342.

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The aeroelasticity and the flutter of the wind turbine blade have been emphasized by related fields. The flutter of the wind turbine blade airfoil and its condition will be focused on. The eigenvalue method and the time domain analysis method will be used to solve the flutter of the wind turbine blade airfoil respectively. The flutter problem will be firstly solved using eigenvalue approach. The flutter region, where the flutter will occur and anti-flutter region, where the flutter will not occur, will be obtained directly by judging the sign of the real part of the characteristic roots of the blade system. Then the time domain analysis of flutter of wind turbine blade will be carried out through the use of the four-order Runge-Kutta numerical methods, the flutter region and the anti-flutter region will be gotten in another way. The time domain analysis can give the changing treads of the aeroelastic responses in great detail than those of the eigenvalue method. The flap displacement of wind turbine blade airfoil will change from convergence to divergence, and change from divergence to convergence extremely suddenly. During the flutter region, the flutter of wind turbine blade will occur extremely dramatically. The flutter region provided by the time domain analysis of the flutter of the blade airfoil accurately coincides with the results of eigenvalue approach, therefore the simulation results are reliable and credible.

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19

Hancock, G. J., J. R. Wright, and A. Simpson. "On the teaching of the principles of wing flexure-torsion flutter." Aeronautical Journal 89, no. 888 (October 1985): 285–305. http://dx.doi.org/10.1017/s0001924000015050.

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This note attempts to clarify some basic ideas, and correct some common misunderstandings, on wing flexure-torsion flutter. Topics include:(i) an understanding of the physics of wing flexure-torsion flutter through a number of specific examples,(ii) an examination of the energy interpretation of the physics of flutter, indicating its limited usefulness,(iii) a discussion of the significant differences between wing flexure-torsion flutter and the Duncan flutter engine,(iv) a graphical representation to assess the contribution of various parameter to flutter onset,(v) subcritical response below the critical flutter speed,(vi) some practical wing flutter considerations.

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20

Shi, Pengtao, Jihai Liu, Yingsong Gu, Zhichun Yang, and Pier Marzocca. "Full-Span Flying Wing Wind Tunnel Test: A Body Freedom Flutter Study." Fluids 5, no. 1 (March 16, 2020): 34. http://dx.doi.org/10.3390/fluids5010034.

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Aiming at the experimental test of the body freedom flutter for modern high aspect ratio flexible flying wing, this paper conducts a body freedom flutter wind tunnel test on a full-span flying wing flutter model. The research content is summarized as follows: (1) The full-span finite element model and aeroelastic model of an unmanned aerial vehicle for body freedom flutter wind tunnel test are established, and the structural dynamics and flutter characteristics of this vehicle are obtained through theoretical analysis. (2) Based on the preliminary theoretical analysis results, the design and manufacturing of this vehicle are completed, and the structural dynamic characteristics of the vehicle are identified through ground vibration test. Finally, the theoretical analysis model is updated and the corresponding flutter characteristics are obtained. (3) A novel quasi-free flying suspension system capable of releasing pitch, plunge and yaw degrees of freedom is designed and implemented in the wind tunnel flutter test. The influence of the nose mass balance on the flutter results is explored. The study shows that: (1) The test vehicle can exhibit body freedom flutter at low airspeeds, and the obtained flutter speed and damping characteristics are favorable for conducting the body freedom flutter wind tunnel test. (2) The designed suspension system can effectively release the degrees of freedom of pitch, plunge, and yaw. The flutter speed measured in the wind tunnel test is 9.72 m/s, and the flutter frequency is 2.18 Hz, which agree well with the theoretical results (with flutter speed of 9.49 m/s and flutter frequency of 2.03 Hz). (3) With the increasing of the mass balance at the nose, critical speed of body freedom flutter rises up and the flutter frequency gradually decreases, which also agree well with corresponding theoretical results.

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21

Sudha, U. P. V., G. S. Deodhare, and K. Venkatraman. "A comparative assessment of flutter prediction techniques." Aeronautical Journal 124, no. 1282 (October 27, 2020): 1945–78. http://dx.doi.org/10.1017/aer.2020.84.

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ABSTRACTTo establish flutter onset boundaries on the flight envelope, it is required to determine the flutter onset dynamic pressure. Proper selection of a flight flutter prediction technique is vital to flutter onset speed prediction. Several methods are available in literature, starting with those based on velocity damping, envelope functions, flutter margin, discrete-time Autoregressive Moving Average (ARMA) modelling, flutterometer and the Houbolt–Rainey algorithm. Each approach has its capabilities and limitations. To choose a robust and efficient flutter prediction technique from among the velocity damping, envelope function, Houbolt–Rainey, flutter margin and auto-regressive techniques, an example problem is chosen for their evaluation. Hence, in this paper, a three-degree-of-freedom model representing the aerodynamics, stiffness and inertia of a typical wing section is used(1). The aerodynamic, stiffness and inertia properties in the example problem are kept the same when each of the above techniques is used to predict the flutter speed of this aeroelastic system. This three-degree-of-freedom model is used to generate data at speeds before initiation of flutter, during flutter and after occurrence of flutter. Using these data, the above-mentioned flutter prediction methods are evaluated and the results are presented.

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22

Wang, Yaoyi, Ye Sun, Shaoqi Jiang, and Wenbo Li. "Design and Motion Simulation Analysis of a Novel 2D Bionic Flutter Aircraft." Journal of Physics: Conference Series 2242, no. 1 (April 1, 2022): 012016. http://dx.doi.org/10.1088/1742-6596/2242/1/012016.

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Abstract In order to improve the symmetry of the flutter mechanism in the bionic flutter aircraft, and then improve the overall motion stability of the flutter aircraft. In this paper, an innovative flutter wing configuration is designed based on a planar crank-slider mechanism and a sparrow model. The geometric relationship of the flutter mechanism is established, the motion of the flutter aircraft is modeled, and the dimensions of the model are optimized. The geometric relationship of the flutter structure was simulated and analyzed by CATIA. The results show that the upper limit angle of the designed flutter structure is βmax=25.82° and the lower limit angle is βmin=6.34°. The CATIA simulation data are consistent with the theoretical values of the established structural geometry model. Meeting the needs of small and medium-sized flutter aircraft.The design provides a theoretical basis for the design and development of the bionic flutter vehicle and the fabrication of a solid prototype.

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23

Sánchez-Borque, P., L. Bravo Calero, A. Miracle Blanco, C. García-Talavera, A. Porta Sánchez, J. A. Cabrera Rodríguez, and J. M. Rubio Campal. "Flutter auricular." Medicine - Programa de Formación Médica Continuada Acreditado 13, no. 45 (November 2021): 2627–31. http://dx.doi.org/10.1016/j.med.2021.11.002.

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24

Walton, Dean, Michael Bonello, and Malcolm Steiger. "Diaphragmatic flutter." Practical Neurology 18, no. 3 (February 1, 2018): 224–26. http://dx.doi.org/10.1136/practneurol-2017-001830.

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A 78-year-old woman presented with involuntary movements of her abdomen, which started after a right hemispheric stroke. She had irregular, variable, hyperkinetic predominantly right-sided abdominal wall movements. MR scan of brain confirmed a recent infarct in the right occipitotemporal lobe and the right cerebellum. Diaphragmatic fluoroscopy confirmed high-frequency flutter as the cause of her abdominal movements and confirmed the diagnosis of van Leeuwenhoek’s disease. Anthonie van Leeuwenhoek first described this condition in 1723 and had the condition himself. He was a Dutch businessman who is often acknowledged as the first microscopist and microbiologist. He disagreed with his physician who attributed his ailment as being of cardiac origin. Diaphragmatic flutter is a rare disorder that requires a high index of suspicion with symptoms including abnormal abdominal wall movements, dyspnoea and respiratory distress. Despite medical treatment, the patient was still highly symptomatic, so she is currently being considered for a phrenic nerve crush.

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25

Glancy, D. Luke, Brent J. Rochon, Fred Henry Rodriguez, and April A. Sandifer. "Pseudoventricular Flutter." Baylor University Medical Center Proceedings 20, no. 2 (April 2007): 187. http://dx.doi.org/10.1080/08998280.2007.11928282.

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26

WALDO, ALBERT L. "Atrial Flutter:." Journal of Cardiovascular Electrophysiology 8, no. 3 (March 1997): 337–52. http://dx.doi.org/10.1111/j.1540-8167.1997.tb00798.x.

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27

MARY-RABINE, LUC, VÉRONIQUE MAHAUX, ANDRÉ WALEFFE, and HENRI KULBERTUS. "Atrial Flutter:." Journal of Cardiovascular Electrophysiology 8, no. 3 (March 1997): 353–58. http://dx.doi.org/10.1111/j.1540-8167.1997.tb00799.x.

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28

ASHE, J., T. C. HAIN, D. S. ZEE, and N. J. SCHATZ. "MICROSACCADIC FLUTTER." Brain 114, no. 1 (1991): 461–72. http://dx.doi.org/10.1093/brain/114.1.461.

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29

Touray, Musa, Lila Saiah, Julien Ombelli, Jean-Yves Sovilla, and Pierre Wyss. "Ocular Flutter." Infectious Diseases in Clinical Practice 12, no. 6 (November 2004): 356–57. http://dx.doi.org/10.1097/01.idc.0000144908.73945.c6.

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30

Mortchéléwicz, Guy Daniel. "Flutter simulations." Aerospace Science and Technology 4, no. 1 (January 2000): 33–40. http://dx.doi.org/10.1016/s1270-9638(00)00116-4.

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31

Bauer, Martin L. "Flutter Flap." Chest 115, no. 6 (June 1999): 1757. http://dx.doi.org/10.1378/chest.115.6.1757.

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32

Marks, John H., and Douglas N. Homnick. "Flutter Flap." Chest 115, no. 6 (June 1999): 1757. http://dx.doi.org/10.1016/s0012-3692(15)38331-8.

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33

Spodick, David H. "Atrial Flutter." American Journal of Geriatric Cardiology 9, no. 3 (May 2000): 170. http://dx.doi.org/10.1111/j.1076-7460.2000.80029.x.

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34

Lemos, João, Cristina Duque, Rui Araújo, João Castelhano, Eric Eggenberger, and Carla Nunes. "Head flutter." Neurology 89, no. 17 (October 23, 2017): 1841. http://dx.doi.org/10.1212/wnl.0000000000004583.

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35

Greene, Alyssa C. "Flutter Point." Pleiades: Literature in Context 40, no. 2 (2020): 153–56. http://dx.doi.org/10.1353/plc.2020.0114.

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36

Olsson, S. Bertil. "ATRIAL FLUTTER." Pacing and Clinical Electrophysiology 12, no. 7 (July 1989): 1171–73. http://dx.doi.org/10.1111/j.1540-8159.1989.tb01955.x.

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37

SCHEINMAN, MELVIN M., and YANFEI YANG. "Atrial Flutter:." Pacing and Clinical Electrophysiology 27, no. 3 (March 2004): 379–81. http://dx.doi.org/10.1111/j.1540-8159.2004.00446.x.

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38

Garg, Ashok, and Gregory K. Feld. "Atrial flutter." Current Treatment Options in Cardiovascular Medicine 3, no. 4 (July 2001): 277–89. http://dx.doi.org/10.1007/s11936-001-0090-x.

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39

Olshaker, Jonathan S. "Atrial flutter." Journal of Emergency Medicine 6, no. 1 (January 1988): 55–59. http://dx.doi.org/10.1016/0736-4679(88)90252-1.

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40

Wellens, H. J. J. "Atrial flutter." Clinical Cardiology 20, no. 9 (September 1997): 819. http://dx.doi.org/10.1002/clc.4960200922.

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41

Hoffmayer, Kurt S., and Nova Goldschlager. "Pseudoatrial flutter." Journal of Electrocardiology 41, no. 3 (May 2008): 201. http://dx.doi.org/10.1016/j.jelectrocard.2008.02.027.

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42

Yang, Lei, Fei Shao, Qian Xu, and Ke-bin Jiang. "Flutter Performance of the Emergency Bridge with New-Type Cable-Girder." Mathematical Problems in Engineering 2019 (March 17, 2019): 1–14. http://dx.doi.org/10.1155/2019/1013025.

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Based on the proposed emergency bridge scheme, the flutter performance of the emergency bridge with the new-type cable-girder has been investigated through wind tunnel tests and numerical simulation analyses. Four aerodynamic optimization schemes have been developed in consideration of structure characteristics of the emergency bridge. The flutter performances of the aerodynamic optimization schemes have been investigated. The flutter derivatives of four aerodynamic optimization schemes have been analyzed. According to the results, the optimal scheme has been determined. Based on flutter theory of bridge, the differential equations of flutter of the emergency bridge with new-type cable-girder have been established. Iterative method has been used for solving the differential equations. The flutter analysis program has been compiled using the APDL language in ANSYS, and the bridge flutter critical wind speed of the optimal scheme has been determined by the program. The flutter analysis program has also been used to determine the bridge flutter critical wind speed of different wind-resistance cable schemes. The results indicate that the bridge flutter critical wind speed of the original emergency bridge scheme is lower than the flutter checking wind speed. The aerodynamic combined measurements of central-slotted and wind fairing are the optimal scheme, with the safety coefficients larger than 1.2 at the wind attack angles of −3°, 0°, and +3°. The bridge flutter critical wind speed of the optimal scheme has been determined using the flutter analysis program, and the numerical results agree well with the wind tunnel test results. The wind-resistance cable scheme of 90° is the optimal wind cable scheme, and the bridge flutter critical wind speed increased 31.4%. However, in consideration of the convenience in construction and the effectiveness in erection, the scheme of wind-resistance cable in the horizontal direction has been selected to be used in the emergency bridge with new-type cable-girder.

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Liu, Jieshan, Fan Wang, Yang Yang, and Renhuai Liu. "Nonlinear Flutter Analysis for a Long-Span Suspension Bridge." Shock and Vibration 2021 (July 16, 2021): 1–20. http://dx.doi.org/10.1155/2021/5572429.

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The wind-induced flutter of the long-span suspension bridge structure is extremely harmful to the bridge. Therefore, it is necessary to study the nonlinear problem of wind-induced flutter. Here, the nonlinear flutter problem of a long-span suspension bridge with cubic torsional stiffness is analyzed by the equivalent linearization method. The system has Hopf bifurcation and limit cycle oscillations (LCOs) under critical wind speed. Replacing the nonlinear stiffness term of the original nonlinear equation with the equivalent linear stiffness, we can obtain the equivalent linearized equation of the nonlinear flutter system and the solution, critical wind speed, and flutter frequency of the suspension bridge flutter system. At the same time, the system has a limit cycle vibration, and the Hopf bifurcation point is obtained. Compared with the numerical method, the calculation results are consistent. The influence of the damping ratio on the flutter system is analyzed. Increasing the system damping ratio can increase the flutter critical wind speed and reduce the amplitude of LCOs. The influence of cubic torsional stiffness on the flutter system is analyzed. The increase of the cubic stiffness coefficient does not change the critical state of flutter, but reduces the amplitude of LCOs.

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Abbasi, A. A., and J. E. Cooper. "Statistical evaluation of flutter boundaries from flight flutter test data." Aeronautical Journal 113, no. 1139 (January 2009): 41–51. http://dx.doi.org/10.1017/s0001924000002761.

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AbstractA methodology is described that determines the statistical confidence bounds on the results from flight flutter tests: modal parameter estimates, flutter margin values and flutter speed estimates, without the need for Monte-Carlo simulation. The approach is based on least squares statistics and eigenvalue perturbation theory applied to the various stages of the analysis process, starting with frequency and damping estimation through to the flutter margin calculations. The technique is demonstrated upon a number of data sets from aeroelastic simulations of flight flutter tests.

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Li, Wenjie, and Shujin Laima. "Experimental Investigations on Nonlinear Flutter Behaviors of a Bridge Deck with Different Leading and Trailing Edges." Applied Sciences 10, no. 21 (November 3, 2020): 7781. http://dx.doi.org/10.3390/app10217781.

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Recently, the nonlinear flutter behavior of long-span suspension bridges has attracted attention. Unlike the classical theory of bridge flutter, the stable limit cycle oscillations (LCO) have occurred for some bluff aerodynamic configurations when the inflow velocity exceeded a specific critical value. To explore the influence of aerodynamic configurations on flutter behaviors a series of flutter tests for spring-suspended sectional models were conducted. When the leading edges and trailing edges with various shapes were installed at the sectional models, different flutter types occurred. In the test, the self-excited forces and flutter responses were measured. Then, the characteristics of coupling vibration and aerodynamic hysteresis of the two kinds of flutter were analyzed and compared. Finally, the role of the phase difference between self-excited forces and displacements was discussed in the mechanism difference of the classical flutter and the postflutter LCO. As the leading edge became the bluffer, the results showed that the type of flutter gradually transformed from classical divergent flutter to postcritical LCO and the torsional mode played a more important role in the flutter than in the vertical mode. For the postflutter LCO, there was a negative feedback pattern, i.e., as the vibration amplitude increased, the phase difference gradually decreased, and the energy input to the dynamic system did not grow rapidly, which limited the further vibration divergence and resulted in a stable LCO.

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HAN, Jiangxu, Nan LIU, Xiaoming SHI, Jin GUO, Song WANG, and Xianpeng YU. "Flutter test of rudder with real servo actuator in continuous transonic wind tunnel." Xibei Gongye Daxue Xuebao/Journal of Northwestern Polytechnical University 40, no. 2 (April 2022): 401–6. http://dx.doi.org/10.1051/jnwpu/20224020401.

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Flutter wind tunnel test is an important approach of investigation of transonic flutter characteristics of flight vehicle. Comparing with the blow-down wind tunnel, the long-running and low dynamic pressure capabilities of continuous transonic wind tunnel are very suitable for flutter test. The flutter safety protection and analysis of dynamic signals are developed. The safety protection control software, rapid reduction of Mach number and dynamic pressure, model debris catch screen are integrated, which can provide safety protection of test model and wind tunnel. During the test process, the flutter boundary can be achieved by interpolating the reciprocal of spectrum peak. The flutter tests of rudder are conduct through two methods of step and continuous varying dynamic pressure. It is illustrated that the error of flutter dynamic pressure is relatively small, less than 5% between the two methods. Meanwhile, the feedback effect of the real servo actuator on the flutter characteristics is hard to be obtained via numerical simulation. It is demonstrated that the flutter dynamic pressure has been increased by 10% due to the feedback effect.

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47

Dunnigan, Ann, D. Woodrow Benson, and David G. Benditt. "Atrial Flutter in Infancy: Diagnosis, Clinical Features, and Treatment." Pediatrics 75, no. 4 (April 1, 1985): 725–29. http://dx.doi.org/10.1542/peds.75.4.725.

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The clinical features and treatment of atrial flutter in eight infants (four male and four female) less than 2 months of age are presented. Atrial flutter was noted during the first week of life in six of the infants and between 6 and 8 weeks of life in the other two infants. Four of the eight infants had associated structural or functional cardiovascular disease, and in three infants a central venous pressure catheter was present in the atrium at the time atrial flutter was diagnosed. Classic flutter waves were apparent on 12-lead ECGs in only two infants. In six infants, flutter waves were not obvious on standard ECGs, but transesophageal electrogram recordings demonstrated the presence of atrial flutter with second degree atrioventricular block. The atrial cycle length during flutter ranged from 135 to 180 ms (mean 149 ms; mean atrial rate 403 beats per minute); there was a 2:1 ventricular response to atrial flutter. Successful termination of atrial flutter was accomplished using three modes of electrical cardioversion in seven of the eight infants: direct curent cardioversion in one, transvenous atrial pacing in one, and transesophageal atrial pacing in five. One asymptomatic infant converted to normal sinus rhythm 24 hours following digoxin administration. One infant had multiple atrial flutter recurrences and required chronic procainamide therapy. In seven of the eight infants, no recurrences have been noted in 6 months to 31/2 years of follow-up. These results demonstrate that atrial flutter may be difficult to diagnose in infants with tachycardia unless transesophageal electrogram recording is utilized for evaluation. In these eight infants, atrial flutter was frequently associated with underlying cardiac disease and/or the presence of central venous pressure catheters in the atrium. Acute treatment with electrical conversion was sufficient in most infants; only one infant required chronic drug therapy to prevent recurrences of atrial flutter.

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Zheng, Hua, Zhenglong Wu, Shiqiang Duan, and Jiangtao Zhou. "Research on Feature Extracted Method for Flutter Test Based on EMD and CNN." International Journal of Aerospace Engineering 2021 (February 27, 2021): 1–10. http://dx.doi.org/10.1155/2021/6620368.

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Due to the inevitable deviations between the results of theoretical calculations and physical experiments, flutter tests and flutter signal analysis often play significant roles in designing the aeroelasticity of a new aircraft. The measured structural response from aeroelastic models in both wind tunnel tests and real fight flutter tests contain an abundance of structural information, but traditional methods tend to have limited ability to extract features of concern. Inspired by deep learning concepts, a novel feature extraction method for flutter signal analysis was established in this study by combining the convolutional neural network (CNN) with empirical mode decomposition (EMD). It is widely hypothesized that when flutter occurs, the measured structural signals are harmonic or divergent in the time domain, and that the flutter modal (1) is singular and (2) its energy increases significantly in the frequency domain. A measured-signal feature extraction and flutter criterion framework was constructed accordingly. The measured signals from a wind tunnel test were manually labeled “flutter” and “no-flutter” as the foundational dataset for the deep learning algorithm. After the normalized preprocessing, the intrinsic mode functions (IMFs) of the flutter test signals are obtained by the EMD method. The IMFs are then reshaped to make them the suitable size to be input to the CNN. The CNN parameters are optimized though the training dataset, and the trained model is validated through the test dataset (i.e., cross-validation). The accuracy rate of the proposed method reached 100% on the test dataset. The training model appears to effectively distinguish whether or not the structural response signal contains flutter. The combination of EMD and CNN provides effective feature extraction of time series signals in flutter test data. This research explores the connection between structural response signals and flutter from the perspective of artificial intelligence. The method allows for real-time, online prediction with low computational complexity.

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Zheng, Hua, Junhao Liu, and Shiqiang Duan. "Flutter Test Data Processing Based on Improved Hilbert-Huang Transform." Mathematical Problems in Engineering 2018 (August 12, 2018): 1–8. http://dx.doi.org/10.1155/2018/3496870.

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Flutter tests are conducted primarily for the purpose of modal parameter estimation and flutter boundary prediction, the accuracy of which is severely affected by the acquired data quality, structural modal density, and nonstationary conditions. An improved Hilbert-Huang Transform (HHT) algorithm is presented in this paper which mitigates the typical mode mixing effect via modulation. The algorithm is validated by theory, by numerical simulation, and per actual flight flutter test data. The results show that the proposed method could extract the flutter model parameters and predict the flutter speed more accurately, which is feasible for the current flutter test data processing.

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Gao, Hui, Feng Wang, Qinghai Guan, Huifang Hou, and Jiawu Li. "Research on the Flutter Stability of Bridge Sections Based on an Empirical Formula of an Aerostatic Three-Component Coefficient." Buildings 12, no. 8 (August 11, 2022): 1212. http://dx.doi.org/10.3390/buildings12081212.

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In order to study the relationship between an aerostatic three-component coefficient (ATCC) and bridge flutter and to quickly evaluate the flutter performance of bridges, we proposed a method based on the empirical formula of the ATCC. The correlation between the flutter driving term and the critical flutter wind speed V of nine bridges (six types of girder sections) was analyzed, and its rationality was verified using wind tunnel test results. The results showed that the flutter stability of the X-term damping-driven type, i.e., the slotted box girder, was the best; the flutter stability of the X + D-term damping-driven type, i.e., the H-shape bridge deck, was the worst; the flutter stability of D-term damping-driven type was measured as being between these two values. The gray correlation analysis method was used to analyze the correlation between the ATCC and the critical flutter wind speed. As well as the relationship between the ATCC and aerodynamic damping, an empirical parameter, K, based on the ATCC, was proposed for use in determining the D-term damping-driven flutter. The flutter stability of three types of girder sections was analyzed using parameter K, and the results of the analysis were consistent with the wind tunnel test results. The results show that the ATCC obtained from the segmental model force test can be used to preliminarily realize the rapid comparison and selection of flutter aerodynamic measures for bridges.

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