The main goal of this article is to analyze the sensitivity and find the most effective property among structural properties that have the most significant impact on the Flutter velocity of a composite wing. For this purpose, the corresponding Aeroelastic equations of a composite wing have been derived using the Euler-Bernoulli beam model and discretized by the Galerkin method. Based on Jones's unsteady aerodynamic model, aerodynamic loads have been incorporated into the aeroelastic model. Then, Flutter velocity was determined through eigenvalue analysis of the obtained aeroelastic equations. The Flutter velocity changes with a specific interval of each input. With the help of reverse engineering, the effects of structural properties (including material properties and effective stiffness) and their sensitivity were determined. The results show that the Torsional Effective Stiffness has the most significant effect and high sensitivity on Flutter velocity. In this work, other parameters (including flow properties, wing geometry, and airfoil) are assumed to be unchangeable. The geometry of the wing is considered rectangular and straight.

The body freedom Flutter phenomenon is one of the aeroelastic instabilities that occurs due to the coupling of the aeroelastic bending mode of the wing with the short-period mode in the flight dynamics of the aircraft. By using the aeroservoelastic model and applying closed loop control, this phenomenon can be suppressed in the operating conditions of the aircraft and the velocity of this event can be increased. The simplest model aircraft capable of displaying this instability includes the flexible wing and the planar flight dynamics model. For this purpose, the wing structure is modeled using the Euler-Bernoulli beam and, the theory of minimum variable state is used to model unstable aerodynamics to make the conditions suitable for modeling the system in state space. In the control section, the elevator is used as the control surface and LQR theory with Kalman filter is used to body freedom Flutter suppression. Finally, the effect of adding a closed loop control to increase the body freedom Flutter velocity and the limitations of this work are studied.

The mechanism of typical atrial Flutter (AFL) has been well established. The isthmus between the tricuspid annulus and Eustachian ridge has been recognized as a critical part for maintaining the typical AFL circuit and the target site for ablation. However, a subtype of AFL, as double-wave reentry [lower loop reentry], has been described. This arrhythmia is due to the presence of 2 activation wavefronts rotating simultaneously. In this case report, we presented a case of counter-clockwise AFL with such activation circuit.

This study aims at Flutter characteristics of orthotropic plates subjected to supersonic flow. The plate is subjected to uniform in-plane forces (Nx, Ny) and its edges are assumed to be elastically restrained (with various degree) against rotation. This type of boundary conditions covered a wide range of B.C's from simply support to clamped supports. The analytical solution is obtained using classical plate theory. Frequency equations of these systems are very large and difficult to solve. A simple method of solving this type of equations has been used in order to investigate the Flutter characteristics of 011hotropic plates. The effect of plate geometry, material propel1ies, in-plane load and boundary condition are presented and discussed.      

An analytical solution is given to investigate the vibrations of a membrane under the effect of an incoming fluid flow perpendicular to it. The membrane is located at the stagnation point of the flow and is of finite width but infinite length. A rigid wall extends through the finite width of the membrane to infinity. The flow is considered to be a small perturbation on the two dimensional potential stagnation flow solution due to the vibrations of the membrane, and the membrane is modeled by the linear vibration equation. The resulting coupled problem is solved by a Galerkin procedure and the eigenvalue equation relating the membrane frequency to the other parameters is derived.

It has been well-established that common atrial Flutter is due to intra-atrial macroreentry and its reentry circuit locates in the right atrium. This reentry circuit has been characterized to involve an area of slow conduction identifiable electrophysiologically at the low post-eroseptal right atrium and anatomical narrow isthmus surrounded by the inferior vena cava, coronary sinus ostium and tricuspid valve annulus. We performed radiofrequency catheter ablation for common atrial Flutter using anatomical approach in one patient. In this report, we discuss the efficacy of catheter ablative therapy and its results in our patient

Mutual interactions-between aerodynamic and structural forces cause aeroelasticity that is very important in aircraft wings. In this paper, instability of a wing in dynamic situation that is called Flutter is considered for a composite wing in subsonic flows. The "Strip Theory" approach is used to calculate the aerodynamic forces along the wing. For this reason, displacements along the wing and Flutter speed are determined using the "Assumed Mode Method ". In this method, the displacement along the wing is assumed by definite boundary conditions. The stored potential and kinetic energy in the wing, as well as the generalized aerodynamic forces and moments on the wing, are determined. By employing Lagrange’s equations, the wing motion is formulated. A Computer program has been developed to calculate the speed of the wing instability, the effects of the elastic axis and the center of gravity has been investigated on the stability of the wing. The Flutter speed is calculated for a certain wing, which the data is available, and a suitable elastic axis has been determined for a specified center of gravity.

Background: Neonatal Cardiac Arrhythmias are found in 1% to 5% of newborns during the first 10 days of life. The most common symptomatic arrhythmia in the neonatal period is Supra Ventricular Tachicardia(SVT), which has an incidence of 1/25, 000. Idiopathic neonatal atrial Flutter (AFL) is a rare rhythm disorder usually occurring in the first days of life and characterized by sustained tachycardia in newborns and infants with an atrial rate around 340-580 beats/minute(BMP). AFL may manifest as asymptomatic tachycardia, congestive heart failure, or hydrops and may be life-threatening and fatal. Case presentation: We reported a 38 weeks female neanate presented with tachycardia during the first physical examination and recieved adenosine therapy and cardioversion. Conclusion: AFL, as a rare but life-threatening rhythm disorder in the fetal and neonatal period that can cause fetal hydrops and infant death, should be considered by neonatologists.