Sharif Digital Repository

Damage detection and structural health monitoring using the electromechanical impedance method has been accepted as an effective technique between various approaches of nondestructive evaluation. Many efforts have been made on experimental methods for obtaining the impedance of structures. However, expensive experimental methods encourage researchers to develop theoretical models. In this paper, a new theoretical model is developed for damage detection of L-shaped beams, which are basic components in frame structures, with an embedded piezoelectric wafer active sensor. For this purpose, a chirp signal of voltage is used to activate a piezoelectric patch for inducing local strains that lead... 

One of the equivalent formulations of the Kadison–Singer problem which was resolved in 2013 by Marcus, Spielman and Srivastava, is the “paving conjecture”. In this paper, we first extend this result to real stable polynomials. We prove that for every multi-affine real stable polynomial satisfying a simple condition, it is possible to partition its set of variables to a small number of subsets such that the “restriction” of the polynomial to each subset has small roots. Then, we derive a probabilistic interpretation of this result. We show that there exists a partition of the underlying space of every strongly Rayleigh process into a small number of sets such that the restriction of the point... 

In this research, nanoparticle translocation through cell membrane has been studied and simulated. To this end, gold nanoparticles have been selected as the main carrier of the drug and have been functionalized with some selected ligands. The partial charges of the ligands have been calculated using quantum mechanics based on HF technique with 6-31Gd basis set. To achieve the realistic shape of a drug, the number and arrangement of ligands loaded on the gold nanoparticle have been optimized. After determining the properties such as diffusion coefficient and validating the results with experimental data, a MARTINI coarse-grained mapping of the drugs is created. The coarse-grained model of the... 

In this research, nanoparticle translocation through cell membrane has been studied and simulated. To this end, gold nanoparticles have been selected as the main carrier of the drug and have been functionalized with some selected ligands. The partial charges of the ligands have been calculated using quantum mechanics based on HF technique with 6-31Gd basis set. To achieve the realistic shape of a drug, the number and arrangement of ligands loaded on the gold nanoparticle have been optimized. After determining the properties such as diffusion coefficient and validating the results with experimental data, a MARTINI coarse-grained mapping of the drugs is created. The coarse-grained model of the... 

The electro-mechanical impedance (EMI) method has been accepted as an effective technique for detecting damages in the Structural health monitoring (SHM). EMI at any point of the structure depends on material properties, geometry and boundary conditions that all appears in dynamic stiffness of the structure. In spite of the expensive experimental methods for measuring the mechanical impedance, or the cheaper one electromechanical impedance, of structures, various analytical methods could be substitutions for them. In this paper, an analytical method is developed to obtain the EMI response of L-shaped beams through calculating the dynamic stiffness of the structure. To verify the model, an... 

Recently, bonded composite patch repair, because of its significant advantages over traditional methods, has been highly accepted in several industries, particularly in aerospace applications. In this paper, a multi-scale finite element algorithm is proposed to simulate crack growth of repaired plates under fatigue load by considering the effects of composite micro-scale properties. The algorithm is verified through conducting an experimental set up and the proposed model is in reasonable agreement with experiments. The influences of different fiber volume fractions (VF), number of layers and fiber orientation of composite patch on the fatigue responses of adhesively bonded patch are... 

Recently, bonded composite patch repair, because of its significant advantages over traditional methods, has been highly accepted in several industries, particularly in aerospace applications. In this paper, a multi-scale finite element algorithm is proposed to simulate crack growth of repaired plates under fatigue load by considering the effects of composite micro-scale properties. The algorithm is verified through conducting an experimental set up and the proposed model is in reasonable agreement with experiments. The influences of different fiber volume fractions (VF), number of layers and fiber orientation of composite patch on the fatigue responses of adhesively bonded patch are... 

With the advent of the Internet of Things (IoT), the development of self-powered sensors has received much attention. Introducing triboelectric nanogenerators (TENGs) as a power source that converts mechanical movement into electrical signals has been admired recently. Moreover, the monitoring of humidity has become enormously essential in several technological contexts from environment monitoring to biomedical applications, thus joining these two subjects provides a huge benefit in achieving self-powered humidity sensors. Here, in this research, facile, low-priced and self-powered humidity sensors are fabricated utilizing transition-metal dichalcogenides (TMD) nanosheets. Semi-vertical SnS2...