Sharif Digital Repository

In this paper we propose a neuro-fuzzy architecture for Web content taxonomy using hybrid of Adaptive Resonance Theory (ART) neural networks and fuzzy logic concept. The search engine called Kavosh1 is equipped with unsupervised neural networks for dynamic data clustering. This model was designed for retrieving images without metadata and in estimating resemblance of multimedia documents; however, in this work only text mining method is implemented. Results show noticeable average precision and recall over search results. © 2007 IEEE  

In this paper we propose a content-based text and image retrieval architecture using Fuzzy Adaptive Resonance Theory neural network. This method is equipped with an unsupervised mechanism for dynamic data clustering to deal with incremental information without metadata such as in web environment. Results show noticeable average precision and recall over search results. © 2006 IEEE  

The present work reports the synthesis of a Pt-modified NiO–Al2O3 nanocomposite derived from graphene-supported layered double hydroxide (Pt–NiO/G) and demonstrates its catalytic activity. The resulting Pt–NiO/G nanocomposite was characterized by FT-IR, XRD, FE-SEM, TEM and XPS techniques and used for catalytic reduction of p-nitrophenol (P-NP) to p-aminophenol (P-AP). The influence of graphene on catalytic activity was comparatively considered by preparation of Pt–NiO nanoparticles derived from layered double hydroxide. The superior catalytic performance of Pt–NiO/G was ascribed to the synergistic effect between Pt and NiO. Furthermore, reduction of P-NP was considered to follow a... 

Ag2O particles were loaded on the surface of ZnCr-LDH via an anion-exchange precipitation approach by using privilege of the memory trace feature of the LDH-type materials. The structural properties of the resulted photocatalyst were explored by different spectroscopic and microscopic methods. The photocatalytic studies on acid black degradation ascertained that the prepared Ag2O/ZnCr-LDH nanocomposite represented an observably increased degradation performance of organic pollutants compared with pure Ag2O and ZnCr-LDH. This improved photocatalytic performance can be ascribed to the enhanced surface area, good order distributing of particles and effective charge carrier transfer and... 

Metal Organic Frameworks (MOFs) have received enormous attention in catalysis field due to their special structures and various promising applications. One of the intriguing applications of MOFs is utilization of them as precursors for synthesis of metal oxide nanomaterials. Base on this strategy, in this work, we have applied Cu-MOF to prepare a series of noble metal nanoparticles (Ag and Au) decorated CuO (M/CuO) as efficient catalyst. As-prepared nanocomposites were characterized by various analytical techniques and their catalytic performances appraised by using of the catalytic reduction of p-nitrophenol to p-aminophenol as a reliable model reaction. Experimental results suggest that... 

A novel approach is proposed to combine the strengths of GA and GP to optimize rule sets and membership functions of fuzzy systems in a co-evolutionary strategy in order to avoid the problem of dual representation in fuzzy systems. The novelty of proposed algorithm is twofold. One is that GP is used for the structural part (Rule sets) and GA for the string part (Membership functions). The goal is to reduce/eliminate the problem of competing conventions by co-evolving pieces of the problem separately and then in combination. Second is exploiting the synergism between rules sets and membership functions by imitating the effect of "matching" and friendship in cooperating teams of humans,... 

In present study, an efficient method was used to synthesis Au and Pt nanoparticles on Ni modified MoS2 (MNi/MoS2 (M = Au and Pt). The morphology and structure of the prepared products were characterized using different microscopic and spectroscopic methods. The as-synthesized MNi/MoS2 nanocomposites were applied for catalytic reduction of p-nitrophenol (P-NP) in the presence of NaBH4. P-NP is one of the prevalent contaminants in wastewaters, while its corresponding aromatic amine (4-aminophenol) is a precious intermediate for manufacturing of important materials such as pharmaceuticals. The obtained catalytic results indicated that noble metal nanoparticles significantly affect catalytic... 

Magnetic carbon nanotubes (MCNTs) have been widely studied for their potential applications in medicine, diagnosis, cell biology, analytical chemistry, and environmental technology. Introduction of MCNTs paved the way for the emergence of new approaches in nanobiotechnology and biomedicine as a result of their multifarious properties embedded within either the carbon nanotubes (CNTs) or magnetic parts. Numerous preparation techniques exists for functionalizing CNTs with magnetic nanoparticles, and these versatile strategies lay the ground for the generation of novel and versatile systems which are applicable to many industries and biological areas. Here, we review and discuss the recent... 

In this paper we have studied both DC size effect and anomalous skin effect caused by surface and grain boundary scattering on the resistivity of Cu thin films by a Monte Carlo method. Contribution of each scattering mechanism and the interaction between them are analyzed separately. A simple and fast numerical recursive method is also introduced to guess the structure of electric field and distribution of current inside the thin film to evaluate the surface resistance instead of complicated analytical formulas  

A novel visible-light-driven Ag3VO4/Ag3PO4/Ag photocatalyst was successfully synthesized via an anion-exchange reaction and characterized by X-ray diffraction, field emission scanning electron microscopy, X-ray photoelectron spectroscopy, UV-vis diffuse-reflectance spectroscopy and Fourier transform infrared spectroscopy. The photocatalytic activities of prepared catalysts were evaluated by degradation of acid blue 92 (AB92) aqueous solutions under visible light irradiation. The photocatalytic results indicated that the synthesized Ag3VO4/Ag3PO4/Ag hybrid displays a significantly enhanced activity in degradation of acid blue 92 under visible light compared with pure Ag3VO4. The improved... 

In this study, MoS2/reduced graphene oxide (rGO) was used as a cocatalyst to synthesize very highly efficient Cu2O/MoS2/rGO for cooperative catalytic applications. The resulting nanocomposite was characterized by various analytical techniques and applied for catalytic reduction of 4-nitrophenol (4-NP) to 4-aminophenol and photocatalytic degradation of Acid blue 92. Cu2O/MoS2/rGO composite presents superior performance to pure Cu2O particles in both catalytic and photocatalytic reactions. This excellent activity demonstrates synergistic effect of MoS2/rGO as a cocatalyst in the nanocomposite. The role of the active sites in the reduction of 4-NP and degradation of dye was discussed and... 

Cu-MOF/rGO nanocomposite was synthesized by a one-step hydrothermal method and used as proper support for Cu2O particles. Various microscopic and spectroscopic methods were applied to characterize the morphology of Cu2O/Cu-MOF/rGO nanocatalyst. Catalytic results of 4-nitrophenol reduction in the presence of NaBH4 indicate that as-synthesized nanocomposite shown significant improved activity compared with pure Cu2O particles. Enhanced catalytic performance of nanocomposite can be ascribed to the high adsorption ability of Cu-MOF and effective electron transfer due to the presence of rGO. A possible mechanism was proposed for catalytic reduction of 4-nitrophenol over Cu2O/Cu-MOF/rGO. © 2019... 

Cu-based metal organic framework/rGO was used as an effective cocatalyst to synthesis novel Ag3VO4/Cu-MOF/rGO nanocomposite. The resulting photocatalysts were characterized by different microscopic and spectroscopic methods. The photocatalytic degradation studies on acid blue 92 showed that Ag3VO4/Cu-MOF/rGO nanocomposite indicated significant improved activity compared with pure Ag3VO4 and Cu-MOF/rGO. The improved photocatalytic activity of nanocomposite was attributed to the increased surface area and effective charge carrier separation and transport in the nanocomposite. © 2019 Elsevier Ltd  

Induction motor parameter estimation is generally needed for such purposes as fault detection and the achievement of high dynamic performance drives. This paper is an attempt to use variable structure control (VSC) methodology for the on-line estimation of several significant mechanical and electrical induction motor parameters. The estimated parameters are rotor resistance, magnetizing inductance, stator resistance and viscous damping coefficient In this combined control/estimation method, we propose to apply field-oriented control to the non-linear model of induction motor, and then transform the model by Input-state linearization into canonical form. Application of variable structure... 

Background: The issue of medial image resolution enhancement is one of the most important topics for medical imaging that helps improve the performance of many post-processing aspects like classification and segmentation towards medical diagnosis. Objective: Our aim in this paper is to evaluate different types of pixel selection models in terms of pixel originality in medical image reconstruction problems. A previous investigation showed that selecting far original pixels has highly better performance than using near unoriginal/estimated pixels while magnifying some benchmarks in digital image processing. Material and Methods: In our technical study, we apply two classical inter-polators,... 

The Internet of Things (IoT) technology enables numerous things with different processing power and storage capacity to communicate and share data with each other. Considering the constrained devices of the IoT network in terms of processing and storage, designing a lightweight authentication scheme is quite important. So in this paper, we propose a lightweight authentication scheme based on Chebyshev Chaotic Maps. In the proposed scheme we apply a hierarchical structure to define different access controls for various entities. We then provide a formal analysis via the BAN logic to show the security of our scheme. Moreover, we compare our proposed scheme with previous ones in terms of... 

The Internet of Things (IoT) technology enables numerous things with different processing power and storage capacity to communicate and share data with each other. Considering the constrained devices of the IoT network in terms of processing and storage, designing a lightweight authentication scheme is quite important. So in this paper, we propose a lightweight authentication scheme based on Chebyshev Chaotic Maps. In the proposed scheme we apply a hierarchical structure to define different access controls for various entities. We then provide a formal analysis via the BAN logic to show the security of our scheme. Moreover, we compare our proposed scheme with previous ones in terms of... 

In this work Halloysite nanotubes were used to synthesis a series of modified acrylamide/Quince seeds-based hydrogels (Poly (AAm-co-QS)/Haln). The as-prepared Poly (AAm-co-QS)/Haln hydrogels displayed improved performance as adsorbent in elimination of methylene blue (MB) from aqueous solution. The structures of the prepared Poly (AAm-co-QS)/Haln hydrogels were identified by XRD, FT-IR, FE-SEM, BET, TGA and EDX. Effect of pH value on the swelling behavior and dye adsorption performance of as-prepared hydrogels was explored. The adsorption MB results suggested that the adsorption kinetics fitted the pseudo-second-order model. The adsorption experiments at various pH condition indicated that... 

In this study, a series of Zirconium-based MOF and chitosan composites (MOF-808/chitosan) were synthesized as efficient adsorbent for Cr(VI) ions elimination from aqueous solution. MOF-808/chitosan structure and morphology was characterized by FE-SEM, EDX, XRD, BET, zeta potential analysis, FT-IR, XPS techniques. The kinetic studies ascertained that Cr(VI) adsorption over MOF-808/chitosan followed pseudo-second-order kinetic model. The adsorption isotherms fitted the Langmuir isotherm model, implying on homogeneously adsorption of Cr(VI) on the surface of MOF-808/chitosan. According to the Langmuir model, the maximum capacity was obtained to be 320.0 mg/g at pH 5. Thermodynamic investigation... 

Photovoltaic (PV) panels provide a suitable way for the direct conversion of solar energy into electricity. The electrical output and efficiency of PV modules are dependent on working temperature. The present study contributes to investigate the efficiency of utilizing a flat plate closed-loop pulsating heat pipe (CLPHP) to cool down a PV panel in both thermal and economic aspects. Accordingly, a numerical investigation is employed to obtain the surface temperature and electrical gain of the PV panel through four scenarios, including natural cooling without additional equipment, CLPHP-based passive cooling, CLPHP-based active cooling, and a conventional flat plate cooling methods. The...