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S.E. Khadem

Bio: S.E. Khadem is an academic researcher from Tarbiat Modares University. The author has contributed to research in topics: Nonlinear system & Vibration. The author has an hindex of 22, co-authored 39 publications receiving 994 citations.

Papers
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Journal Article•DOI•
TL;DR: In this article, the effect of an attached/coupled nonlinear energy sink (NES) on energy suppression of a cantilever beam under shock excitation was investigated and the performance was optimized through variation of different parameters.

80 citations

Journal Article•DOI•
TL;DR: In this article, a nonlinear model was developed for a drillstring system in deviated well with axially moving motion and axial loading, using the perturbation techniques.

71 citations

Journal Article•DOI•
TL;DR: The main goal of this paper is to improve the Ensemble Empirical mode decomposition (EEMD) algorithm and combine it with a new proposed denoising process and the higher order spectra to increase the accuracy and speed of the fault severity and type detection.
Abstract: In the bearing health assessment issues, using the adaptive nonstationary vibration signal processing methods in the time-frequency domain, lead to improving of early fault detection. On the other hand, the noise and random impulses which contaminates the input data, are a major challenge in extracting fault-related features. The main goal of this paper is to improve the Ensemble Empirical mode decomposition (EEMD) algorithm and combine it with a new proposed denoising process and the higher order spectra to increase the accuracy and speed of the fault severity and type detection. The main approach is to use statistical features without using any dimension reduction and data training. To eliminate unrelated components from faulty condition, the best combination of denoising parameters based on the wavelet transform, is determined by a proposed performance index. In order to enhance the efficiency of the EEMD algorithm, a systematic method is presented to determine the proper amplitude of the additive noise and the Intrinsic Mode Functions (IMFs) selection scheme. The fault occurrence detection and the fault severity level identification are performed by the Fault Severity Index (FSI) definition based on the energy level of the Combined Fault-Sensitive IMF (CFSIMF) envelope using the central limit theorem. Also, taking the advantages of a bispectrum analysis of CFSIMF envelope, fault type recognition can be achieved by Fault Type Index (FTI) quantification. Finally, the proposed method is validated using experimental data set from two different test rigs. Also, the role of the optimum denoising process and the algorithm of systematic selection of the EEMD parameters are described regardless of its type and estimating the consistent degradation pattern.

64 citations

Journal Article•DOI•
TL;DR: In this article, the stability and bifurcation of trivial and non-trivial steady-state responses are analyzed using Routh-Hurwitz criterion using multiple scales method.

57 citations

Journal Article•DOI•
TL;DR: In this paper, the primary resonances of a simply supported in-extensional rotating shaft with large amplitudes were studied and the effects of diametrical mass moment of inertia, eccentricity and external damping were investigated on the steady state response of the rotating shaft.

56 citations


Cited by
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Journal Article•DOI•
TL;DR: Three types of nonlinear dampers that are widely utilized in practical engineering are reviewed in this paper: the nonlinear energy sink (NES), particle impact damper (PID), and nonlinear viscousdamper (NVD), respectively.

203 citations

01 Jan 2005
TL;DR: In this paper, an approximate analytical expression of the critical pull-in gap with Casimir force is presented by the perturbation theory, from which one can notice the nonlinear effect of Casimir forces on the pullin parameters.
Abstract: Casimir effect on the critical pull-in gap and pull-in voltage of nanoelectromechanical switches is studied. An approximate analytical expression of the critical pull-in gap with Casimir force is presented by the perturbation theory. The corresponding pull-in parameters are computed numerically, from which one can notice the nonlinear effect of Casimir force on the pull-in parameters. The detachment length has been presented, which increases with increasing thickness of the beam.

192 citations

Journal Article•DOI•
TL;DR: A broad survey of the drillstring vibration modeling literature can be found in this paper, where the state-of-the-art models for predicting axial, torsional and bending vibrations (uncoupled and coupled), boundary condition assumptions, equation formulation methods, and applications to vibration mitigation are reviewed.

169 citations

Journal Article•DOI•
Hu Ding1, Li-Qun Chen1•
TL;DR: A comprehensive review of state-of-the-art researches on NESs, highlighting possible complex dynamics resulting in a NES coupled to a structure and suggesting further promising directions, such as NESs for multidirectional vibration reduction, NESs with nonlinearities beyond the cubic, and potential deterioration caused by a NES.
Abstract: Nonlinear energy sink (NES) is an appropriately designed nonlinear oscillator without positive linear stiffness. NES can suppress vibrations over a wide frequency range due to its targeted energy transfer characteristics. Thus, investigations on NES have attracted a lot of attention since a NES was proposed. Designs, analysis, and applications of NESs are still active since different configurations are needed in various practical circumstances. The present work provides a comprehensive review of state-of-the-art researches on NESs. The work begins with a survey of the generation of a NES and its important vibration control characteristics. The work highlights possible complex dynamics resulting in a NES coupled to a structure. The work also summarizes some significant design on the implements of optimal damping effects and the offsets of NES shortcomings. Then, the work details the applications of NESs in all engineering fields. The concluding remarks suggest further promising directions, such as NESs for multidirectional vibration reduction, NESs with nonlinearities beyond the cubic, potential deterioration caused by a NES, low-cost NESs, NESs for extremely low frequency range, and NESs integrated into active vibration controls. There are 383 references in the review, including some publications of the authors.

157 citations

Journal Article•DOI•
TL;DR: In this article, a comprehensive review of articles about rotating composite beams and blades is presented, which addresses analytical, semi-analytical and numerical studies dealing with dynamical problems involving adaptive/smart/intelligent materials (e.g., piezoelectric materials, electrorheological fluids, shape memory alloys, etc.), damping and vibration control, advanced composite materials, complicating effects and loadings, and experimental methods.
Abstract: Rotating composite beams and blades have a wide range of applications in various engineering structures such as wind turbines, industrial fans, and steam turbines. Therefore, proper understanding of such structures is of a great importance. As a result, the behavior of rotating composite beam structures has received a lot of attention. This paper presents a comprehensive review of scholarly articles about rotating composite beams as published in the past decades. The review addresses analytical, semi-analytical and numerical studies dealing with dynamical problems involving adaptive/smart/intelligent materials (e.g. piezoelectric materials, electrorheological fluids, shape memory alloys, etc.), damping and vibration control, advanced composite materials (e.g. functionally graded materials and nanocomposites), complicating effects and loadings (e.g. added mass, tapered beams, initial curve and twist, etc.), and experimental methods. Moreover, the influence of Vlasov or restrained warping, out-of-plane warping, transverse shear, arbitrary cross-sectional geometry, trapeze phenomena, swept tip, size-dependent effect, as well as other areas that have been considered in research, are reviewed in depth. The review concludes with a presentation of the remaining challenges and future research needs.

136 citations