The Transient dynamics of a beam mounted on springer-damper support and equipped with a nonlinear energy sink (NES) is investigated under the effects of shock loads. The equations of motion are derived using the Hamilton’ s principle leading to four hybrid ordinary and partial differential equations and descritized using the Galerkin method. An adaptive Newmark method is employed for accurate and efficient numerical simulation and the results are used to assess the efficiency of the NES by conducting various parametric studies. The mechanisms of targeted energy transfer from the beam to the NES are indicated using the wavelet transform and Hilbert– Huang transform of the responses. Numerous modes are recognized to contribute to the response and the modes with smaller particiaption of the rigid-body motions are found to be strongly engaged in the Transient resonance capture (TRC) at the initial stage of the motion. The modes with dominant rigid-body motions are, however found to be less engaed in an effective TRC. The enhanced empirical mode decomposition, with different masking signals are used to extract narrow-band intrinsic mode functions (IMFs) and simultaneous 1: 1 Transient resonances are observed between different IMFs of the responses especially at the initial stage of the motion.

This paper presents a finite element formulation for the dynamics analysis of the steady and Transient states of a nonlinear piezoelectric beam. A piezoelectric beam with damping is studied under harmonic excitation. A numerical method is used for this analysis. In the paper, the central difference formula of four order is used and compared with the central difference formula of two order in the time response of the structure. The NPBDA program is developed with Matlab software. In this program, the Newmark technique for dynamic analysis is used, the Newton-Raphson iterative and Simpson methods are used for the nonlinear solution. To verify the NPBDA results, the experimental results of Malatkar are used for the nonlinear vibration analysis of a beam without piezoelectric properties. Then, the piezoelectric effect on the frequency mode values and the time response are obtained. Afterwards, the modulation frequency in the nonlinear beam and the piezoelectric effect in this parameter are verified.

In this paper, a simplified model for a multi-wave length erbium-doped fiber amplifier and an optical fiber inverter is introduced. Through averaging over the length of the active medium, the balance system of equations is considerably simplified. Consequently, a system of ordinary differential (instead of partial differential) equations is obtained. Gain dynamics of an all-optical stabilized multi-wavelength erbium-doped fiber amplifier (EDFA) and Transient response of an optical fiber inverter are analyzed, using the solution of the system of ordinary differential equations. Theoretical conclusions are in satisfactory agreement with the published experimental results.

Background: Previous literatures have shown a Transient ischemic attack (TIA) mimic rate of 9-31%. We aimed to ascertain the proportion of stroke mimics amongst suspected TIA patients.Methods: A prospective observational study was performed in Ghaem Hospital, Mashhad, Iran during 2012-2013. Consecutive TIA patients were identified in a stroke center.The initial diagnosis of TIA was made by the resident of neurology and final diagnosis of true TIA versus TIA mimics was made after 3 months follow-up by stroke subspecialist.Results: A total of 310 patients were assessed during a 3-month period of which 182 (58.7%) subjects were male and 128 (41.3%) were female. Ten percent of the patients was categorized as a TIA mimic. The presence of hypertension, aphasia, duration of symptoms, and increased age was the strongest predictor of a true TIA. Migraine was the most common etiology of stroke mimic in our study.Conclusion: It seems that many signs and symptoms have low diagnostic usefulness for discrimination of true TIA from non-cerebrovascular events and predictive usefulness of any sign or symptom should be interpreted by a stroke neurologist.

In the current study, the inabilities resulting from the interaction of two Newtonian immiscible fluids, including water and base oil, during Transient consecutive injection-suction in a Hele-Shaw cell, was studied. For injection-suction purposes, base oils with viscosities of 150, 920, and 1506 cP were used. The highest continuous flow rates for three techniques including pseudo-sinusoidal, percussive time-dependent, and constant-flow rate were 10, 20, and 30 mL/min, respectively. The volume of fluid injected or extracted remained consistent across all three methods. The injection-suction process was repeated for five full cycles to analyze the impact of frequency on the outcome. The primary goal was to study how to eliminate interfacial instabilities and restore the circular shape of the fluid-fluid interface after each cycle. It was found that the percussive and constant-flow rate methods were unable to achieve this objective. Results showed that the growth rate of interfacial instabilities was slower with the pseudo-sinusoidal method compared to the other methods. Increasing the flow rate in the constant-flow rate method resulted in more oil packets being created. The pseudo-sinusoidal method did not show instabilities like water droplets, fingers, or oil packets, unlike the constant-flow rate and percussive methods. Overall, the pseudo-sinusoidal method was found to be the most suitable for restoring the fluid-fluid interface to its original stable state. However, increasing the number of cycles could lead to more instabilities, making it harder to return to the initial stable interface.

The purpose of this paper is to analyze the flow field structure in Transient state and performance of secondary injection system for thrust vectoring in divergent section of a two-dimensional nozzle. Secondary injection for thrust vectoring in a two-dimensional nozzle is studied by solving threedimensional Reynolds-averaged equations by means of fluent solver. Spalart-Allmaras model was used to model the fluid behavior near the walls. Density-based solver and explicit formulation are employed in the computational model. Results show that the solution of interfered field in the Transient-state is more accurate than steady-state, especially in the initial injection. In addition, various testing showed that the maximum side force would be in the injection angle of twenty degrees and with increasing pressure ratio, we have more side force. At the end it was observed that by sketching the exit gases deviation according to time, we could be informed of desired secondary injection time in order to achieve required deviation around pitch axis, and the required force to achieve desired deviation angle. The innovation of this paper is the solution of interfered field in Transient state, and of course the injection from the optimal point.