Sharif Digital Repository

Advanced control techniques are required for the vibrations suppression of the seated human body in different places like automotive and public transportation lines. In this paper, an active multivariable control strategy is applied to a seated human body model and results are simulated and examined via MATLAB. Dynamic equations of the model are derived using Lagrange method and they are linearized around the equilibrium point of the system. After assessing the deficiencies of the previous models and control strategies proposed for the human body, an active control method is presented based on pole placement analysis. This control strategy is designed for a realistic model of the human body... 

Sulfur mustard (SM) is a vesication chemical warfare agent for which there is currently no antidote. Despite years of research, there is no common consensus about the pathophysiological basis of chronic pulmonary disease caused by this chemical warfare agent. In this study, we combined chemometric techniques with nuclear magnetic resonance (NMR) spectroscopy to explore the metabolic profile of sera from SM-exposed patients. A total of 29 serum samples obtained from 17 SM-injured patients, and 12 healthy controls were analyzed by Random Forest. Increased concentrations of seven amino acids, glycerol, dimethylamine, ketone bodies, lactate, acetate, citrulline and creatine together with the... 

A new resonance phenomenon is discussed and demonstrated by experiment in a dual-polarization cavity. The resonance is formed by waves bouncing between two anisotropic metasurfaces placed at the cavity ends. The simple metasurfaces are designed to preserve the handedness of circularly polarized waves upon reflection. The standing waves resulting from such reflections do not have nodes and antinodes. A theoretical solution to the resonance condition is discussed, both for plane-waves and equivalent guided waves. The concept is then experimentally applied to dual-mode guided waves, demonstrating a very short cavity at X-band. This brings new possibilities for resonator design and can... 

Environmental issues and energy crisis have caused the world attention to the renewable energies; especially the wind power, since they have low cost and high reliability. To achieve higher capacity, wind turbines have increased in their size over the years. However, the large size of the modern turbines has exacerbated the problem of vibrations, which results in lower efficiency and power generation. Because of the large deformations, the conventional linear theories cannot model the blades accurately, due to the importance of nonlinear effects in large scale wind turbines. In this research, a nonlinear kinematic model of the wind turbine blade is developed using the Hamilton's principle.... 

In this letter, a new approach to perform edge detection is presented using an all-dielectric complimentary metal-oxide-semiconductor-compatible metasurface. Our design is based on the guided-mode resonance, which provides a high quality factor resonance to make the edge detection experimentally realizable. The proposed structure is easy to fabricate, and it can be exploited for detection of edges in two dimensions due to its symmetry. In addition, a tradeoff between gain and the resolution of edge detection is discussed, which can be adjusted using appropriate design parameters. The proposed edge detector potentially can be used in ultrafast analog computing and image processing. ©... 

In this paper, a route to ultra-broadband absorption is suggested and demonstrated by a feasible design. The high absorption regime (absorption above 90%) for the suggested structure ranges from visible to mid-infrared (MIR), i.e., for the wavelength varying from 478 to 3278 nm that yields an ultra-wide band with the width of 2800 nm. The structure consists of a top-layer-patterned metal-insulator-metal (MIM) configuration, into the insulator layer of which, an ultra-thin 5 nm layer of manganese (Mn) is embedded. The MIM configuration represents a Ti-Al2O3-Ti tri-layer. It is shown that, without the ultra-thin layer of Mn, the absorption bandwidth is reduced to 274 nm. Therefore, adding only... 

Temporal coupled mode theory (CMT) has so far been applied phenomenologically in the analysis of optical cavity-waveguide structures, and relies on a priori knowledge of the to-be-excited resonator mode. Thus a rigorous derivation from Maxwell's equations, and without any prior knowledge of the resonator type is needed. In this paper we derive temporal CMT of optical cavities coupled to waveguides. Starting from Maxwell's equations and considering a proper expansion of the modes of the waveguide and resonator, and using mode orthogonality, the temporal CMT for this structure is obtained. We show that this formulation is general and can be applied to both traveling wave and standing wave type... 

Temporal coupled mode theory (CMT) has so far been applied phenomenologically in the analysis of optical cavity-waveguide structures, and relies on a priori knowledge of the to-be-excited resonator mode. Thus a rigorous derivation from Maxwell's equations, and without any prior knowledge of the resonator type is needed. In this paper we derive temporal CMT of optical cavities coupled to waveguides. Starting from Maxwell's equations and considering a proper expansion of the modes of the waveguide and resonator, and using mode orthogonality, the temporal CMT for this structure is obtained. We show that this formulation is general and can be applied to both traveling wave and standing wave type... 

Teratozoospermia is one of conditions that can cause male infertility. The mechanism of teratozoospermia remains unclear. The knowledge of the metabolites in human seminal plasma (HSP) is meaningful for the pathological study of teratozoospermia. Analysis of changed metabolites in HSP can help understand the cellular mechanism, find the novel biomarkers and subsequently design a diagnosis test. In this study, the analysis of samples performed by proton nuclear magnetic resonance spectroscopy (1H NMR spectroscopy) to identify the various metabolites, with the aim of finding metabolic profiles and biomarkers related to male infertility. Eighteen de-regulated metabolites were identified in... 

Variable-temperature 1H and 13C NMR spectroscopy are used to investigate barrier of C-N rotation in series of amides, such as N-benzoyl pyrrolidine, N-(4-chlorobenzoyl) pyrrolidine, N-(4-methoxybenzoyl) pyrrolidine, N-(4-chlorobenzoyl) piperidine, and N-(4-methoxybenzoyl) piperidine. Δ G298≠ of 65.2, 60.6, 58.8, 60.1, and 57.1 kJ mol-1are found for the above compounds, respectively. Theoretical studies were done for these compounds and the results showed good agreement with the experimental results. Theoretical and experimental results showed that substituted methoxy group on the para position of benzene ring decreases the rotational barrier. Increasing steric effect and therefore... 

A distributed, nonlinear dynamic vibration neutralizer is presented to improve vibration suppression characteristics of harmonically excited structures. The absorber subsection consists of a double-ended cantilever beam carrying intermediate lumped masses. The positions of the moving masses are adjustable along the beam in order to comply with the desired optimal performance. The absorber is assumed to be linearly elastic but with the inextensibility along the neutral axis of the beam. Due to the existence of parametric resonance, nonlinearities of the system begin to affect the motion and hence parametric instability occurs. The necessary and sufficient conditions for the existence of... 

Optical measurement of voltage because of its excellent advantages is studied by several research groups. In this paper, two optically voltage measurement method based on periodic structure have been introduced. First one is based on Bragg reflection effect. The coefficient of reflection from a periodic layered medium depends on properties of periodic structure. In this work a periodic structure on LiNbO3 substrate was considered and under a high voltage electric field perpendicular to surface of layers, refractive indices of substrate have been changed. Performance of reflection versus applied electric field was calculated. Second method was based on Guided-mode resonance effect. Guided... 

With the spread of deadly diseases worldwide, the design of rapid tests to identify causative microorganisms is necessary. Due to the unique properties of gold nanoparticles, these nanoparticles are used in designing rapid diagnostic tests, such as strip tests. The current study aimed to investigate the ability of gold nanoparticles to bind to single-chain variable fragment antibodies. In this study, the biological and chemical methods included Escherichia coli TOP-10 and the Turkevich method to synthesize the gold nanoparticles, respectively. Then, the effect of synthetic nanoparticles on their capability of binding to recombinant antibodies was assessed by agarose gel and UV-vis... 

A cavity resonator containing graphene nanopores (GNPs), along with a metallic layer (Ag, as a reflector) and a dielectric layer (SiO2, as a spacer), has been proposed for broadband wide-angle absorption of light. The GNP/SiO2/Ag multilayers showed high significant increase in the absorption efficiency (with respect to the G/SiO2/Ag multilayer) in a broad spectral range (from ultra-violet (UV) and visible range to near-infrared (NIR)), due to the cavity resonance and absorptions induced by the oxygen-containing functional groups formed around the nanopores of graphene. The dependences of the cavity resonance absorption on the quality of the GNP layer, dimension of the cavity and the incident... 

We investigate the Fano profile in an optomechanical system with two vibrating mirrors. The detuning between their mechanical frequency, leads to the occurrence of double Fano resonances. The Fano profile can be controlled by adjusting the cavity parameters  

We study the effect of laser phase noise on the generation of stationary entanglement between an intracavity optical mode and a mechanical resonator in a generic cavity optomechanical system. We show that one can realize robust stationary optomechanical entanglement even in the presence of non-negligible laser phase noise. We also show that the explicit form of the laser phase noise spectrum is relevant, and discuss its effect on both optomechanical entanglement and ground-state cooling of the mechanical resonator  

The high degree of intensity values in microring resonators needs a careful treatment of nonlinear phenomena. Nonlinear effects are analyzed in coupling problem of ring-ring directional couplers. It has been observed that the nonlinearity affects the coupling device dramatically, and can be used as controlling techniques in such as coupled resonator optical waveguides. © 2007 Elsevier B.V. All rights reserved  

Thermoacoustics describes energy conversion processes, activated by interaction temperature oscillation, accompanying the pressure oscillation in a sound wave, with solid boundaries. In ordinary experience this interaction of sound and heat cannot be observed, because of the very low temperature differences, but under suitable conditions, it can be emphasized and amplified to create remarkable thermodynamic effects such as, steep thermal gradients, powerful convective heat fluxes, and strong sound fields. We designed and constructed a simple thermoacoustic refrigerator with an adjustable mechanical resonator, coupled with the acoustic resonator. Our experimental data showed about % 10... 

A circuit model based on the transmission line theory is proposed to analyze the recently introduced metal-insulator-metal (MIM) complementary split-ring resonators (CSRRs). It is shown that integer and noninteger modes of CSRRs can be characterized by transmission line models with short- and open-circuited terminals. The proposed circuit model is then extended to incorporate side-coupling effects between the CSRRs and straight MIM waveguides. Thereby, simple closed-form expressions are provided for the coupling quality factor. It is shown that waveguide resonator structures based on CSRRs at specific resonance frequency and bandwidth can be smaller than waveguide resonator structures based... 

The authors propose a new design for monolayer superconducting planar flux transformer integrated with a coplanar resonator serving as a gigahertz range tank circuit for high-Tc rf-SQUID magnetometers. Based on the proposed design, which is optimized using the finite element method, the transformer-resonator configuration is made of 200-nm-thick monolayer YBCO film on a crystalline LaAlO3 substrate. In this optimized design, the SQUID magnetometer is coupled through flip-chip configuration with the configuration providing high coupling coefficient between the devices. The design permits coupling of the rf signals to the SQUID efficiently, whereas the transformer is designed to couple the dc...