Classic flutter

This phenomenon is caused by self-excitation of the blade and is aero-elastic. It must be distinguished from classic flutter, since classic flutter is a coupled torsional-flexural vibration that occurs when the freestream velocity over a wing or airfoil section reaches a certain critical velocity. Stall flutter, on the other hand, is a phenomenon that occurs due to the stalling of the flow around a blade. 

The classical flutter is more likely to occur when the coefficient does not reverse its sign as the reduced velocity 27t/K, increases. Basically, the first flexural and torsional modes have major contributions to the state instability. Furthermore, it is more convenient to deal with the equations of motion in the Laplace transform domain. 

Finally, it is mentioned that the results presented in Figs. 3-6 satisfy not only the stability conditions of the single degree of freedom flutter but also that of the classical flutter. Likewise, the required active control force to substantially raise the flutter velocity is rather small [11]. 

Verapamil, proprietaiy name Calan, is a calcium channel blocker that is effective in the treatment of various cardiovascular disorders, including angina (classical and variant), arrhythmias (paroxysmal supraventricular tachycardia), atrial flutter, atrial fibrillation, hypertrophic cardiomyopathy (idiopathic hypertrophic subaortic stenosis), hypertension, congestive heart failure, and Raynaud s phenomenon, along with the preservation of ischemic myocardium and the treatment of migraine headaches. 

It is evident that the modality-specific response extends beyond the classically defined topographic map as revealed by simple indentation stimuli. As shown in O Figure 1 -9b, an indentation stimulus (which activates all three receptors types) to digit D2 produces a fairly focal activation in both Area 3b and Area 1 (outline in red in O Figure l-9c. In response to pressure, flutter, and vibration stimulation, the vector summation map reveals that the strongest responses (most saturated red, green, and blue regions)... 

AV conduction = ventricular rate of 150 beats per minute 3 1 AV conduction = ventricular rate of 100 beats per minute). Atrial flutter may occur in two distinct forms (type I and type II). Type I flutter is the more common classic form with atrial rates of approximately 300 beats per minute and the typical sawtooth pattern of atrial activation, as shown by the surface ECG. Type II flutter tends to be faster, being somewhat of a hybrid between classic atrial flutter and atrial fibrillation. Although the ventricular response usually has a regular pattern, atrial flutter with varying degrees of AV block or that occurs with episodes of atrial fibrillation ( fib-flutter ) can cause an irregular ventricular rate and pulse. 

The classic publication of Frey (17) epitomizes most of the information known today about the therapy of auricular fibrillation with quinidine. He converted to normal sinus rhythm 6 of 10 patients whose auricular fibrillation was complicated by atherosclerosis, mitral stenosis or insufficiency, and rheumatic fever or congestive failure. These patients included other arrhythmias such as auricular flutter or ventricular extra systoles. Some had been digitalized. Conversion occurred after 1.0 to 1.4 g. quinidine given over 2 to 8 days. Frey (33) also distinguished between patients with paroxysmal auricular fibrillation and the more stubborn continuous fibrillation. In this latter group of patients, many of whom had serious cardiac damage, quinidine converted 11/22 to normal rhythm. 

Most bridge flutter instability is experimentally provided for in practical cases by making available two degrees of freedom, bending and torsion, as in classic low-speed airfoil flutter. Bridge... 

Atrial Clutter is rhythm disturbance associated with stmctural heart disease. Atrial Flutter is a form of atrial tachycardia that usually originates in the right atria (Fig. 6.23) and is usually paroxysmal, lasting several hours or days. Longer lasting or chronic flutter is rare. Atrial Flutter and Atrial Fibrillation are closely linked and can alternate in individuals. A prolonged Atrial Flutter often converts itself into Atrial Fibrillation. Flutter can be identified on the ECG by its classic sawtooth like appearance, seen best in lead II, III and aVF. As with Atrial Fibrillation there are no P waves, but instead prominent Flutter F waves (Fig. 6.24). 

In Chap. 3, we mentioned circulatory systems which are described (after linearization) by asymmetric stiffness and/or damping coefficient matrices. Stability of these class of systems has been studied by many authors (see, e.g., [48, 49, 72, 73]). In Sect. 4.2.1 below, we give a classic example where a follower force causes flutter instability. In multi-DOF systems, friction force may act as a follower force and destroy the symmetry of the stiffness and damping matrices resulting in flutter instability known as the mode coupling instability mechanism. This mechanism was first used to explain brake squeal [7]. Ono et al. [74] and Mottershead and Chan [75] studied hard disk drive instability using a similar concept. In Sect. 4.2.2, we study the mode coupling instability mechanism in a simple 2-DOF system with friction. 

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