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Employing Multi-Phase DG Sources as Active Power Filters, Using Fuzzy Logic Controller
Ali Asghar Ghadimi,Mazdak Ebadi 전력전자학회 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.5
By placing distributed generation power sources beside a big nonlinear load, these sources can be used as a power quality enhancer, while injecting some active power to the network. In this paper, a new scheme to use the distributed generation power source in both operation modes is presented. In this scheme, a fuzzy controller is added to adjust the optimal set point of inverter between compensating mode and maximum active power injection mode, which works based on the harmonic content of the nonlinear load. As the high order current harmonics can be easily rejected using passive filters, the DG is used to compensate the low order harmonics of the load current. Multilevel transformerless cascade inverters are preferred in such utilization, as they have more flexibility in current/voltage waveform. The proposed scheme is simulated in MATLAB/SIMULINK to evaluate the circuit performance. Then, a 1kw single phase prototype of the circuit is used for experimental evaluation of the paper. Both simulative and experimental results prove that such a circuit can inject a well-controlled current with desired harmonics and THD, while having a smaller switching frequency and better efficiency, related to previous 3-phase inverter schemes in the literature.
Ali Asghar Memon,Muhammad Mujtaba Shaikh,Syed Sabir Hussain Bukhari,Jong-Suk Ro 한국자기학회 2020 Journal of Magnetics Vol.25 No.2
The look-up data-based modeling of switched reluctance machine and the procedure of validation of experimentally obtained static torque with statistical analysis is presented in this paper. First, the experimental setup for data collection of flux linkage and static torque is established and data is collected at an unequally spaced current and rotor position so that computation of instantaneous phase current and torque can be achieved. Second, the experimental data of static torque is compared with computed data. The computation is done in MATLAB software. Third, for numerical simulations, finite difference approximations and numerical integration schemes are used to compute co-energy and static torque profiles, respectively. The comparison is carried out in terms of different statistical parameters, including absolute and relative error distributions of the measured and computed torque profiles. A correlational study, to observe the extent to which both profiles exhibit a similar trend is also carried out. Finally, the influence of computed torque is carefully analyzed by running machine in single pulse mode and current chopping mode separately. The comparison with experimental data and the statistical analysis of results show the time efficiency, accuracy, and validity of the numerically simulated torque profiles.
Ali Asghar,Mohd Rozi Ahmad,Mohamad Faizul Yahya 한국의류학회 2016 Fashion and Textiles Vol.3 No.1
Of late, a significant amount of research has been carried out using metals for conductive fabrics and composites to obtain the desired level of electromagnetic shielding along with physical and mechanical properties for its durability. However, incorporating these metallic filaments as core or as an integral part of core deteriorate the mechanical properties of textile yarns and ultimately the fabrics’. Moreover, the transparency of fabrics to high frequency/smaller wavelength waves further increases with the attempt to increase the metallic filament diameter. This study, therefore analyses the effects of metallic filament alignment in order to improve the mechanical properties of the resultant hybrid yarns, and devises an alternative method to increase the amount of conductive filament without increasing the diameter of the conducting wire in hybrid yarn structures. The results suggest that the tensile properties of the proposed hybrid cover yarns with conductive filament as covering component is superior as compared to the yarns having a conductive filament in the core, however, the electrical resistance increases with an increase in conductive filament length. The tenacity, elongation and initial modulus values were enhanced several times by incorporating the conductive filament as spiral covering. Moreover, with the proposed alignment method, the amount of copper in hybrid yarn can be increased up to some extent by changing the number of turns of covering component.
Influence of fiber paths on buckling load of tailored conical shells
Ali-Asghar Naderi,Gholam-Hossein Rahimi,Mohammad Arefi 국제구조공학회 2014 Steel and Composite Structures, An International J Vol.16 No.4
The purpose of this paper is to propose a method for evaluation of varying stiffness coefficients of tailored conical shells (TCS). Furthermore, a comparison between buckling loads of these shells under axial load with the different fiber path is performed. A circular truncated conical shell subjected to axial compression is taken into account. Three different theoretical path containing geodesic path, constant curvature path and constant angle path has been considered to describe the angle variation along the cone length, along cone generator of a conical shell are offered. In the TCS with the arbitrary fiber path, the thickness and the ply orientation are assumed to be functions of the shell coordinates and influencing stiffness coefficients of the structure. The stiffness coefficients and the buckling loads of shells are calculated basing on classical shells theory (CST) and using finite-element analysis (FEA) software. The obtained results for TCS with arbitrary fiber path, thickness and ply orientation are derived as functions of shell longitudinal coordinate and influencing stiffness coefficients of structures. Furthermore, the buckling loads based on fiber path and ply orientation at the start of tailored fiber get to be different. The extent of difference for tailored fiber with start angle lower than 20 degrees is not significant. The results in this paper show that using tailored fiber placement could be applied for producing conical shells in order to have greater buckling strengths and lower weight. This work demonstrates the use of fiber path definitions for calculated stiffness coefficients and buckling loads of conical shells.
Asghar Ali,Zuhair S. Khan,Mahmood Jamil,Yaqoob Khan,Nisar Ahmad,S. Ahmed 한국물리학회 2018 Current Applied Physics Vol.18 No.5
We developed sulfonated, reduced graphene oxide (S-RGO) through fuming/concentrated sulfuric acid treatment of graphene oxide (GO) in ambient conditions. It was demonstrated that the optical band gap and electrical conductivity of S-RGO are easily tunable, and depend on the level of reduction and sulfonation of GO. Whereas, reduction and sulfonation were found dependent on SO3 content, acid strength, and gas tightness of the reaction mixture. It's actually the water content of oleum that determines the nature of the final product. The easily adjustable band gap and electrical conductivity suggest that S-RGO can be employed as a potential hole extraction layer (HEL) material for several donor-acceptor systems. For P3HT:PC61BM based inverted polymer solar cells, it was observed that the shape of the JeV curve is tailorable with the choice of HEL. Compared to a 2.75% power conversion efficiency (PCE) attained with PEDOT:PSS, a PCE of 2.80% was achieved with tuned S-RGO. Our results imply that an S-RGO of sufficiently high band gap and conductivity can replace some of the state of the art HEL materials for a host of device applications.
Ali-Asghar Shahamat,Nasrullah Rastegar-Pouyani,Eskandar Rastegar-Pouyani 국립중앙과학관 2019 Journal of Asia-Pacific Biodiversity Vol.12 No.3
Taxonomic evaluation is one of the challenges that are being faced by taxonomists. They use different criteria to evaluate taxonomic validity of a given lineage. In the present study, we evaluate different populations of Trapelus agilis in Iran by using morphoecological approach. Our morphological results confirmed separation of T. agilis khuzestanensis, southeastern Iran and Qom groups, from other central and northeastern groups. Ecological niche of T. agilis khuzestanensis and southeastern, Qom, and northeastern Iranian populations can be differentiated from other groups. Differences are due to local adaptations and the geological history of the taxa. The Central Iranian Plateau aridification, after Zagros Mountain uplifting, created constant environmental conditions, which may have affected the central Iranian groups. Other smaller groups distributed in southeastern Iran, T. agilis khuzestanensis, T. sanguinolentus, and Qom groups are isolated from central populations and adapted locally.
LASER INDUCED SURFACE PROCESSING WITH GOLD NANOPARTICLE ARRAYS EMBEDDED IN A TRANSPARENT MATRIX
ALI ASGHAR ASKARI,ALI REZA BAHRAMPOUR 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2013 NANO Vol.8 No.1
Gold nanoparticles are widely used as high efficient photon–thermal energy converters in a broad range of applications. This paper presents a theoretical investigation on using the optothermal properties of gold nanoparticle arrays to generate nanoscale molten and rubbery regions on the surface of an amorphous polymeric film. Nanoparticles are assumed to be embedded in a transparent silica layer and illuminated with a 7.5 ns pulsed laser at 532 nm. Simulation results are presented for systems with single gold nanoparticles, dimers and chains. Both electromagnetic and thermal interaction between nanoparticles are found to be important factors in determining the result of surface processing. This effect allows us to control the shape and spatial characteristics of the phase transmitted regions with various parameters such as particles size, incident light fluence, polarization and direction, interparticle distance and chain length.
Small scale computational vibration of double-walled CNTs: Estimation of nonlocal shell model
Asghar, Sehar,Khadimallah, Mohamed Amine,Naeem, Muhammad N.,Ghamkhar, Madiha,Khedher, Khaled Mohamed,Hussain, Muzamal,Bouzgarrou, Souhail Mohamed,Ali, Zainab,Iqbal, Zafar,Mahmoud, S.R.,Algarni, Ali,Ta Techno-Press 2020 Advances in concrete construction Vol.10 No.4
In this paper, vibration characteristics of double-walled carbon nanotubes (CNTs) is studied based upon nonlocal elastic shell theory. The significance of small scale is being perceived by developing nonlocal Love shell model. The wave propagation approach has been utilized to frame the governing equations as eigen value system. The influence of nonlocal parameter subjected to diverse end supports has been overtly analyzed. An appropriate selection of material properties and nonlocal parameter has been considered. The influence of changing mechanical parameter Poisson's ratio has been investigated in detail. The dominance of boundary conditions via nonlocal parameter is shown graphically. The results generated furnish the evidence regarding applicability of nonlocal shell model and also verified by earlier published literature.