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Tayebi, Meysam,Tayyebi, Ahmad,Lee, Byeong-Kyu Elsevier Science Publishers 2019 Catalysis today Vol.328 No.-
<P><B>Abstract</B></P> <P>Molybdenum (Mo)-doped Monoclinic Bismuth Vanadate (Mo-BiVO<SUB>4</SUB>; BVO) catalysts were fabricated via a simple dip coating method. We systematically studied the effect of Mo-doping with various concentration (1–5%) in BVO electrode through photoelectrochemical (PEC), Mott-Schottky and impedance measurement. Intermediate heat treatment and number of successive dip coating deposition were utilized to control the monoclinic crystallization and thickness of Mo-BVO photoanodes. Furthermore, the effect of Mo-doping in morphology, structure, chemical states and optical properties of the obtained electrodes were characterized by different physico-chemical and morphological methods BVO with 2% Mo doping (2% Mo-BVO) showed the best PEC performance, of about 15 times higher than that of the pure BVO. Improved charge carrier transport and optimized light absorption obtained upon Mo doping into the BVO crystal lattice while the monoclinic scheelite structure with small band-gap was retained. To understand the effect of Mo-doping, Mott Schottky and Impedance measurement carried out, in order to evaluate the donor concentration and conductivity of pure BVO and Mo-BVO. Interestingly, 2% Mo-BVO showed the maximum donor concentration (5.7E + 27) and minimum flat band potential (V<SUB>fb</SUB> = −0.45) compared to other prepared electrodes. Furthermore, we attempt to discuss the improved PEC performance of Mo-BVO using high donor concentration, up-shifting of Fermi level and consequently facilitating electrons transport in Mo-BVO compared to pure BVO.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Mo-BVO electrodes were fabricated via a four dip-coating cycles method. </LI> <LI> Photocurrent density increased 15-fold for 2% Mo-BVO compared with pure BVO. </LI> <LI> Mott-Schottky results indicated 2% Mo-BVO has the maximum donor concentration. </LI> <LI> The PEC measurement showed shifting of onset potential to lower voltage for Mo-BVO. </LI> <LI> The Impedance data exhibited 2% Mo-BVO has the best PEC performance compared to other photoanodes. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Research on Oscillation-Free Robust Control for Active Joint Dental Automation
Farzin Piltan,Meysam Esmaeili,Mohammad Ali Tayebi,Mahsa Piltan,Mojtaba Yaghoot,Nasri B. Sulaiman 보안공학연구지원센터 2016 International Journal of Hybrid Information Techno Vol.9 No.11
Design a robust oscillation-free controller for multi input-multi output (MIMO) nonlinear uncertain dynamical system (sensitive dental joint) is the main objective in this research. In this paper, robust sliding mode controller will be selected as a main control technique and linear controller will be design to improve the stability and robustness to control of dental joint. The proposed approach effectively combines of design methods from switching sliding mode controller, and linear Proportional-Integral-Derivative (PID) control to improve the performance, stability and robustness of the sliding mode controller. Conventional sliding mode controller has two important subparts, switching and equivalent. Switching part (discontinuous part) is very important in uncertain condition but it causes chattering phenomenon. To solve the chattering, the most common method used is linear boundary layer saturation method, but this method lost the stability. To reduce the chattering with respect to stability and robustness; linear controller is added to the switching part of the sliding mode controller. The linear controller is to reduce the role of sliding surface slope and switching (sign) function. This controller improves the stability and robustness, reduces the chattering as well and reduces the level of energy due to the torque performance as well.
Research on FPGA-Based Controller for Nonlinear System
Farzin Piltan,Maryam Rahmani,Meysam Esmaeili,Mohammad Ali Tayebi,Mahsa Piltan Hamid Cheraghi,Mohammad R. Rashidian,Arzhang Khajeh 보안공학연구지원센터 2015 International Journal of u- and e- Service, Scienc Vol.8 No.3
Many of linear control applications require real-time operation; higher density programmable logic devices such as field programmable gate array (FPGA) can be used to integrate large amounts of logic in a single IC. This work, proposes a developed method to design PD controller (PDC) with optimal- gains using FPGA. The method used to design PD controller is to design it as digital design Proportional and Derivative controller in parallel through the summer. The proposed design is 32-bits FPGA-based controller (32PDC), which uses 32-bits for each input/output variable. The single joint of robot is used to test the controller in simulation environments, using VHDL code for the purpose of simulation in Xilinx. The same design is coded in MATLAB environment (MPDC) in order to make a comparison with the proposed FPGA-based design. PDC needs 16 clock cycles to complete one action with maximum frequency of 108.5 MHz. 32PDC is able to produce an output in 13.24 MHz with the robot system. Therefore, the proposed controller will be able to control a wide range of the systems with high sampling rate and 75.545 ns delays.
Design FPGA-Based Fuzzification Algorithm for Model-free Control Techniques
Farzin Piltan,Maryam Rahmani,Omid Mahmoudi,Meysam Esmaeili,Mohammad Ali Tayebi,Mahsa Piltan,Hamid Cheraghi 보안공학연구지원센터 2016 International Journal of Hybrid Information Techno Vol.9 No.8
Many of fuzzy control applications require real-time operation; higher density programmable logic devices such as field programmable gate array (FPGA) can be used to integrate large amounts of logic in a single IC. This work, proposes a developed method to fuzzifier algorithm with optimal-tunable gains method-using FPGA. The maximum frequency in FPGA-based design is about 72.4 MHz and the delay time in this design is about 13.78 ns. It is observed that this algorithm is able to make as a fast response at 13.78 clock period with 72.4 of a maximum frequency and 2.1 ns for minimum input arrival time after clock. From investigation and synthesis summary, 24.3 for maximum input arrival time after clock with 13.9 MHZ frequencies, this design has 13.78 ns delays for each controller to 46 logic elements and the offset before CLOCK is 82.1 ns.
Tayyebi, Ahmad,Soltani, Tayyebeh,Lee, Byeong-Kyu,Outokesh, Mohammad,Tayebi, Meysam ELSEVIER SCIENCE 2017 JOURNAL OF ALLOYS AND COMPOUNDS Vol.723 No.-
<P><B>Abstract</B></P> <P>Carbon-doped zinc oxide/reduced graphene oxide (C-ZnO/rGO) was prepared by a facile one-pot supercritical methanol method. The synthesized C-ZnO/rGO nanocomposite with flower-like ZnO micro-rods (MRs) synergistically inherited all the advantages of carbon doping and rGO heterojunction and exhibited high photocatalytic activity for the photodegradation of methyl orange (MO) under visible light. The x-ray diffraction (XRD) results indicated that in presence of GO, a new carbon-doped phase was formed at the high temperature and pressure of supercritical methanol. The x-ray photoelectron spectroscopy (XPS) at low binding energies demonstrated that the valence band of C-ZnO-rGO is up-shifted by 0.35 ± 0.05 eV compared to that of ZnO MRs and narrowed the band-gap down to 2.9 eV. Under visible light irradiation, C-ZnO/rGO showed photocatalytic degradation of MO that was greatly increased by 4.5-fold compared to that of pure ZnO MRs. Measuring the photoelectrochemical (PEC) performance illustrated that C-ZnO/rGO showed higher photocurrent density in UV and visible region compared with those of ZnO MRs electrode. In addition, the incorporation of graphene sheets greatly suppressed the photocorrosion and photocurrent density decay of C-ZnO/rGO to only 0.5% and 10%, compared with 27% and 70% for neat ZnO MRs, respectively.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Carbon-doped ZnO/rGO was synthesized by facile one-pot supercritical methanol. </LI> <LI> The carbon-doped and oxygen vacancies enhanced the separation of electron-hole pairs. </LI> <LI> The introduction of graphene improved adsorption and anti-photocorrosion properties. </LI> <LI> Photocatalytic activity of C-ZnO/rGO increased by 4.5-fold compared to ZnO NRs. </LI> <LI> C-ZnO/rGO showed a high and stable photocurrent density in visible region. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>