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Development of Maghemite Glass Fibre Nanocomposite for Adsorptive Removal of Methylene Blue
Muhammad Azeem Ashraf,Jakub Wiener,Assad Farooq,Jana Saskova,Muhammad Tayyab Noman 한국섬유공학회 2018 Fibers and polymers Vol.19 No.8
Maghemite glass fibre nanocomposite with excellent magnetic and adsorption properties was successfully developed from nontoxic and eco-friendly reagents by thermal decomposition approach. The developed nanocomposite was utilized in adsorption of methylene blue which follows Freundlich adsorption isotherm. The excellent value of adsorption capacity (51.31 mg g-1) as compared to other adsorbents recommends its potential role for adsorption phenomenon in multiple applications. The developed nanocomposite can be recycled and reused easily. Surface and other functional characteristics of developed nanocomposite were determined through scanning electron microscopy, X-ray diffraction, raman spectroscopy, energy dispersive X-ray spectroscopy and vibrating sample magnetometer. The obtained results revealed that maghemite glass nanocomposite is a potential tool that can be utilized in waste water treatments.
A Novel Green Stabilization of TiO2 Nanoparticles onto Cotton
Muhammad Tayyab Noman,Muhammad Azeem Ashraf,Hafsa Jamshaid,Azam Ali 한국섬유공학회 2018 Fibers and polymers Vol.19 No.11
Facile embedding of TiO2 nanoparticles onto cotton fabric has been successfully attained by ultraviolet light irradiations. The adhesion of nanoparticles with fibre surface, tensile behaviour and physicochemical changes before and after ultraviolet treatment were investigated by scanning electron microscopy, energy dispersive X-ray and inductive couple plasma-atomic emission spectroscopy. Experimental variables i.e. dosage of TiO2 nanoparticles, temperature of the system and time of ultraviolet irradiations were optimised by central composite design and response surface methodology. Moreover, two different mathematical models were developed for incorporated TiO2 onto cotton and tensile strength of cotton after ultraviolet treatment and used further to testify the obtained results. Self-clean fabric through a synergistic combination of cotton with highly photo active TiO2 nanoparticles was produced. Stability against ultraviolet irradiations and self-cleaning properties of the produced fabric were evaluated.
A Robust PLL Technique using a Digital Lock-In Amplifier under the Non-Sinusoidal Grid Conditions
Muhammad Noman Ashraf,Reyya n Ahmed Khan,Woojin Choi 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5
Due to the recent increasing use of nonlinear loads and Grid Connected Inverters (GCIs), the harmonics are also increasing in the grid. The detrimental effects of the harmonics in the grid include the heating in the equipment and conductors, the misfiring in variable speed drives, the torque pulsations in motors and the asynchronization of the GCIs. Therefore, the standard such as IEEE 519 and P1547 forces the GCIs to meet a certain level of output quality in terms of harmonics, phase and frequency variation. In order to inject the pure active power to the grid, the synchronization between the grid and a GCI by a highperformance Phase Locked Loops (PLLs) is essential. Several kinds of PLL methods to synchronize the GCI under the distorted grid condition have been proposed. However, their performances are significantly degraded under the distorted grid condition, especially with a DC off-set and harmonics. In this paper a novel Digital Lock-in Amplifier (DLA) based PLL is proposed to improve the performance of the PLL under the highly distorted grid condition including the power quality events. Since the proposed DLA-PLL is composed of a robust Phase Sensitive detector (PSD), it is immune to any frequency component except the fundamental and the DC off-set present in the grid can be completely rejected. The superiority of the proposed DLA-PLL is proved by the simulation and experiments by comparing it to the results obtained with the six kinds of conventional PLL methods widely used under distorted grid condition.
Reyyan Ahmad Khan,Muhammad Noman Ashraf,Woojin Choi 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5
The performance of Single Phase Grid Connected Inverters (SPGCIs) get degraded due to several detrimental factors such as the grid voltage harmonics, the dead time effect and the turn ON/OFF of the switches and so on, which cause the harmonics at the output of Grid Connected Inverters (GCIs). Therefore, it is not easy to satisfy the harmonic standards such as IEEE 519 and P1547 without the help of harmonic compensator. In this paper, the Digital Lock-in Amplifier (DLA) based harmonic compensation is proposed, which makes it possible to extract the amplitude and phase information of the harmonics from the output current and compensate it by using a simple PI controller in a feedforward manner. In order to show the superior performance of the proposed harmonic compensation technique, it is compared with those of conventional harmonic compensation methods in terms of the effectiveness of harmonic elimination, complexity and implementation. The validity of the proposed harmonic compensation techniques is verified through the PSIM simulation and experiments with a 5kW SPGCI.