Islamic Azad University

About: Islamic Azad University is a education organization based out in Tehran, Iran. It is known for research contribution in the topics: Population & Catalysis. The organization has 83635 authors who have published 113437 publications receiving 1275049 citations. The organization is also known as: Azad University.

Online knowledge sharing mechanisms: a systematic review of the state of the art literature and recommendations for future research

Abstract: Knowledge sharing is an activity through which knowledge, namely, information, skills, or expertise, is exchanged between people, friends, families, communities or organizations. Online knowledge sharing activities are flourishing with the advent of social media and digital life. However, despite of the importance of the online knowledge sharing methods and mechanisms, there is not any comprehensive and systematic study about studying and analyzing its important techniques. Therefore, the main aim of this paper, the comprehensive, detailed, and systematic study, and survey of the state-of-the-art knowledge sharing mechanisms in an online environments is provided. Also, this paper presents a systematic literature review (SLR) on the online knowledge sharing literatures up to end of 2015. We identified 348 papers, which are reduced to 251 primary studies through our paper selection process. Also, the broad overview of the literature provides insights into potential areas for further research. By providing state-of-the-art information, this survey will directly support academics and practicing professionals in their understanding of developments in online knowledge sharing mechanisms and techniques.

A New Super Wideband Fractal Microstrip Antenna

Abstract: The commercial and military telecommunication systems require ultrawideband antennas. The small physical size and multi-band capability are very important in the design of ultrawideband antennas. Fractals have unique properties such as self-similarity and space-filling. The use of fractal geometry in antenna design provides a good method for achieving the desired miniaturization and multi-band properties. In this communication, a multi-band and broad-band microstrip antenna based on a new fractal geometry is presented. The proposed design is an octagonal fractal microstrip patch antenna. The simulation and optimization are performed using CST Microwave Studio simulator. The results show that the proposed microstrip antenna can be used for 10 GHz -50 GHz frequency range, i.e., it is a super wideband microstrip antenna with 40 GHz bandwidth. Radiation patterns and gains are also studied.

Design and evaluation of chitosan/hydroxyapatite composite nanofiber membrane for the removal of heavy metal ions from aqueous solution

Abstract: The performance of chitosan/hydroxyapatite (Cs/HAp) composite nanofiber membrane prepared by electrospinning process for the removal of lead, cobalt and nickel ions from aqueous solution was investigated. The prepared nanofiber membranes were characterized by FTIR, SEM and BET analysis. A response surface methodology based on Box–Behnken Design (BBD) was used to predict the average diameter of electrospun nanofibers. In optimum conditions (voltage of 18.90 kV, tip-collector distance of 15.60 cm and flow rate of 0.43 ml/h), the minimum experimental fiber diameter was obtained 198 nm which was in good agreement with the predicted value by the BBD analysis (200.6 nm). Then, the adsorption experiments were carried out to investigate the effect of different adsorption parameters, such as contact time, initial concentration and temperature in a batch system. The kinetic and equilibrium data were well described by pseudo-second-order and Langmuir models, respectively. Thermodynamic parameters were evaluated to obtain the nature of adsorption process onto the Cs/HAp composite nanofibers. The obtained results of reusability of nanofiber membrane after five sorption–desorption cycles offer promising potential in industrial activities.