Shiri H.M.,Payame Noor University |
Aghazadeh M.,Laser and Optics Research School
Journal of the Electrochemical Society | Year: 2012
Capsule-like NiO nanoparticles were prepared by heat-treatment of the cathodically electrodeposited nickel hydroxide at 300C for three hours. The hydroxide precursor was deposited galvanostatically onto the stainless steel substrate from aqueous Ni(NO 3) 2 solution (0.01 M). Morphological, structural and chemical characteristics of the synthesized NiO were examined by means of scanning and transmission electron microscopy (SEM and TEM) as well as X-ray diffraction (XRD) and FT-IR spectroscopy. The XRD and TEM results revealed that the oxide products have well-crystallized cubic structure with capsule-like morphology of various length and diameters in the order of 20-70 nm and 10-30 nm, respectively. Capacitive performance of NiO nanocapsules were evaluated by cyclic voltammetry and galvanostatic chargedischarge measurements in a potential window between -0.2 and +0.5 V vs. AgAgCl. Electrochemical measurements revealed that the NiO nanocapsules have a specific faradaic pseudocapacitance as high as 307.2 F g -1 in 1 M KOH solution and good cycle life (approximately displayed 86.4 of its maximum capacitance after 3000 cycle discharging). These results showed that the prepared NiO nanostructure can be recognized as a promising candidate for the supercapacitor applications. © 2012 The Electrochemical Society.
Ruzbehani M.,Laser and Optics Research School
Asian Journal of Control | Year: 2010
A new tracking controller for discrete-time Single Input Single Output (SISO) non-minimum phase (NMP) systems is presented. In the proposed method, after cancellation of poles and cancelable zeros of the system, the controller adds some NMP zeros to compensate the effect of NMP zero (zeros) of the system. As a result, the phase of the overall transfer function will be almost linear and its magnitude approaches unity for all frequencies. The method can be applied even to the systems with complex conjugate NMP zeros. As well, it is applicable to the systems for which the conventional methods cannot properly be used. Furthermore, a generalization of method to continuous-time systems is another given result. Several examples are provided to illustrate the effectiveness of the method. © 2009 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society.
Adelkhani H.,Material Research School |
Ghaemi M.,Golestan University |
Ruzbehani M.,Laser and Optics Research School
International Journal of Electrochemical Science | Year: 2011
Manganese dioxide samples were prepared by pulse current electrodeposition. The effects of the pulse current parameters on the type of hysteresis loop of the adsorption isotherms, the surface area, and nano-structure morphology of the samples were investigated in details by using the Barrett-Joyner-Halenda (BJH) method and the Scanning Electron Microscopy (SEM) technique. Results indicate that the applied duty cycles play key roles in different characteristics of the samples. Samples obtained at duty cycles up to 30% show a decreasing trend of the surface area as well as increasing grain size and represent a type H4 hysteresis as duty cycles decrease. At duty cycle of 30%, the surface area has been increased, whereas at higher duty cycle of 70%, a decrease in surface area and the grain size of samples has been observed. Even though type H2 hysteresis prevailed at duty cycles higher than 70%, an overlapping of both type H4 and H2 hysteresis loops were obtained at duty cycles lower than 70%. These behaviors were explained and discussed on the basis of the formation and dissolution mechanism of the passive layers during on- and off-times. © 2011 by ESG.
Hassanpour A.,K. N. Toosi University of Technology |
Bananej A.,Laser and Optics Research School
Optik | Year: 2013
The effect of time-temperature gradient annealing on the TiO 2 single layers depositing in the same conditions by electron gun were discussed. Investigating the optical properties of the layers which were calculated by envelope method revealed that not only the extinction coefficient but also porous ratio of the layer may affect the laser resistance of the thin films. The experimental results are in a good agreement with theoretical analysis which is based on the well known Yoshida's model. It can be seen the positive impact of higher porous ratio on the laser induced damage threshold values of the TiO 2 thin films. In addition, according to the XRD patterns of samples, it can be seen that our novel annealing procedure have a significant influence on the grain size of the TiO 2 material. Consequently, comparing the laser induced damage threshold showed that different annealing procedures may modify laser resistance of TiO 2 thin films by influencing their optical or structural properties. © 2011 Elsevier GmbH. All rights reserved.
Rashidian Vaziri M.R.,Laser and Optics Research School
Optics Communications | Year: 2015
In an influential paper Jamshidi-Ghaleh and Mansour  (Opt. Commun. 234 (2004) 419), have reported on a new method for measuring the nonlinear refractive index of materials using the rotational moiré deflectometry technique. In the cited work, the authors apply the ray matrix theory for finding the beam deflection angle on the plane of the first grating in the used geometry. To this end, using the parabolic approximation, the exponential term in the beam irradiance is expanded and retaining the first two resultant terms, the nonlinear sample is treated as a thin lens with a position dependent focal length. In this comment, the effective focal length of the nonlinear sample has been rederived in detail using the Gaussian beam theory and it is shown that it must contain a correction factor. The relative error introduced by ignoring this factor can be as large as 73.5-84.4% in determining the nonlinear refractive index of thin samples. © 2014 Elsevier B.V. All rights reserved.