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Namadmalan A.,Jundi-Shapur University of Technology
IEEE Transactions on Industrial Electronics | Year: 2017

This paper presents a universal tuning system for harmonic operation of series-resonant inverters (SRI), based on a self-oscillating switching method. In the new tuning system, SRI can instantly operate in one of the switching frequency harmonics, e.g., the first, third, or fifth harmonic. Moreover, the new system can utilize pulse density modulation (PDM), phase shift (PS), and power-frequency control methods for each harmonic. Simultaneous combination of PDM and PS control method is also proposed for smoother power regulation. In addition, this paper investigates performance of selected harmonic operation based on phase-locked loop (PLL) circuits. In comparison with the fundamental harmonic operation, PLL circuits suffer from stability problem for the other harmonic operations. The proposed method has been verified using laboratory prototypes with resonant frequencies of 20 up to 75 kHz and output power of about 200 W. © 2016 IEEE.

Khoshdast H.,Shahid Bahonar University of Kerman | Abbasi H.,Jundi-Shapur University of Technology | Sam A.,Shahid Bahonar University of Kerman | Noghabi K.A.,Iran National Institute of Genetic Engineering and Biotechnology
Biochemical Engineering Journal | Year: 2012

In this work, surface activity and frothability of rhamnolipid biosurfactant produced by a Pseudomonas aeruginosa MA01 were studied and compared with conventional flotation frothers, i.e. methyl isobutyl carbinol (MIBC), pine oil, Dowfroth-250 (DF-250), and Aerofroth-65 (A-65). FTIR and ES-MS analysis indicated that the product contained two types of commonly found rhamnolipids: l-rhamnosyl-β-hydroxydecanoyl-β-hydroxydecanoate (RL-1) and l-rhamnosyl l-rhamnosyl-β-hydroxydecanoyl-β-hydroxydecanoate (RL-2). Surface tension measurements showed that the rhamnolipid product reduces surface tension more effectively than frothers due to higher molecular weight and the presence of multiple oxygenated groups in its structure, producing more viscous liquid film, which was confirmed with film elasticity calculations. Both surface tension and elasticity values followed the order: rhamnolipid > A-65 > DF-250 > pine oil > MIBC. Frothability of the tested surfactants gave the order: rhamnolipid > A-65 > DF-250 > MIBC > pine oil. © 2011 Elsevier B.V.

Namadmalan A.,Jundi-Shapur University of Technology | Namadmalan A.,Damavand Induction Furnace Company
IEEE Transactions on Industrial Electronics | Year: 2014

This paper presents a bidirectional current-fed parallel resonant push-pull inverter (CFPRPI) for contactless energy conversions. In conventional CFPRPIs, each switch is in series with a blocking diode. Direct zero voltage switching (ZVS) is proposed to remove the series blocking diodes for higher efficiency and boosting ratio. In addition, the modified inverter has bidirectional power flow capability when these blocking diodes are omitted. Resonant tuning of the system is investigated by using a phase-locked loop and a new self-oscillating switching technique (SST). By using the new SST, the inverter has direct ZVS in a wide range of operating frequencies, which is necessary for inductively coupled power transfer systems. Finally, a laboratory prototype with an input voltage of 12 V and a maximum output power of 60 W has been implemented. © 2014 IEEE.

Abbasi H.,Jundi-Shapur University of Technology | Noghabi K.A.,Iran National Institute of Genetic Engineering and Biotechnology | Ortiz A.,University of Murcia
Chemistry and Physics of Lipids | Year: 2012

This work presents a biophysical study on the interactions of a monorhamnolipid (monoRL) produced by Pseudomonas aeruginosa MA01 with model phosphatidylcholine membranes. The molecular characterization of the biological activities, including the modulation of phospholipid membranes structure, of this monoRL biosurfactant is of importance for the validation of this particular Pseudomonas aeruginosa strain as a useful biosurfactant producer. The marked amphiphilic structure of monoRL is expected to result in strong interactions with the phospholipid constituents of membrane bilayers. Incorporation of monoRL into DMPC completely abolished the pretransition, and the main gel to liquid-crystalline phase transition was progressively broadened and shifted to lower temperatures, as observed by differential scanning calorimetry. Partial phase diagrams for DPPC and DSPC indicated near-ideal behavior. However, the DMPC diagram indicated fluid phase immiscibility. X-ray diffraction showed and apparent increase in d-value for DPPC containing monoRL, which might be the result of an effective increase in the bilayer thickness, or in the thickness of the hydration layer between bilayers. FTIR indicated that interaction of monoRL with the phospholipid acyl chains did not result in a large additional disordering of the acyl chain region of the fluid bilayer. Analysis of the CO stretching band of DPPC indicated an important effect of monoRL on the interfacial region of phosphatidylcholine bilayers, which might contribute to explain some of the biological activities of this glycolipid. © 2012 Elsevier Ireland Ltd. All rights reserved.

Keramat A.,Jundi-Shapur University of Technology | Kolahi A.G.,Shahrood University of Technology | Ahmadi A.,Shahrood University of Technology
Journal of Fluids and Structures | Year: 2013

Poisson's ratio in viscoelastic materials is a function of time. However, recently developed waterhammer models of viscoelastic pipes consider it constant. This simplifying assumption avoids cumbersome calculations of double convolution integrals which appear if Poisson's ratio is time-dependent. The present research develops a mathematical model taking the time dependency of Poisson's ratio into account for linear viscoelastic pipes. Poisson's ratio is written in terms of relaxation function and bulk modulus which is assumed to be constant. The relaxation function is obtained from creep function given as the viscoelastic property data of pipe material. The results obtained from the present waterhammer model are compared with the experimental data for two different flow rates. The comparison reveals that with the application of the time-dependent Poisson's ratio and unsteady friction, the viscoelastic data of mechanical tests can directly be used for waterhammer analysis with less need for the calibration of the flow configuration. It was also shown that the creep curve calibrated based on the present model is closer to the actual creep curve than that calibrated based on previous models. © 2013.

Pourjavadi A.,Sharif University of Technology | Zeidabadi F.,Sharif University of Technology | Barzegar Sh.,Jundi-Shapur University of Technology
Journal of Applied Polymer Science | Year: 2010

Novel types of highly swelling hydrogels were prepared by grafting crosslinked polyacrylamide-co-poly-2-acrylamido-2-methylpropane sulfonic acid (PAAm-co-PAMPS) chains onto sodium alginate (Na-Alg) through a free radical polymerization method. The superabsorbent formation was confirmed by Fourier transform infrared spectroscopic (FTIR). The controlled release behavior of diclofenac sodium (DS) from superabsorbent polymer was factinvestigated, and shown that the release profiles of DS from superabsorbent polymer were slow in simulated gastric fluid (SGF, pH 1.2) over 3 h, but nearly all of the initial drug content was released in simulated intestinal fluid (SIF, pH 7.4) within 21 h after changing media. Overall the results demonstrated that biodegradable superabsorbent could successfully deliver a drug to the intestine without losing the drug in the stomach, and could be potential candidates as an orally administrated drug delivery system. © 2010 Wiley Periodicals, Inc.

Tahmasebi N.,Jundi-Shapur University of Technology | Mahdavi S.M.,Sharif University of Technology
Applied Surface Science | Year: 2015

In this study, colloidal tungsten oxide nanoparticles were fabricated by pulsed laser ablation of tungsten target using the first harmonic of a Nd:YAG laser (1064 nm) in deionized water. After ablation, a 0.33 g/lit HAuCl4 aqueous solution was added into as-prepared colloidal nanoparticles. In this process, Au3+ ions were reduced to decorate gold metallic state (Au0) onto colloidal tungsten oxide nanoparticles surface. The morphology and chemical composition of the synthesized nanoparticles were studied by AFM, XRD, TEM and XPS techniques. UV-Vis analysis reveals a distinct absorption peak at ∼530 nm. This peak can be attributed to the surface plasmon resonance (SPR) of Au and confirms formation of gold state. Moreover, X-ray photoelectron spectroscopy reveals that Au ions' reduction happens after adding HAuCl4 solution into as-prepared colloidal tungsten oxide nanoparticles. Transmission electron microscope shows that an Au shell has been decorated onto colloidal WO3 nanoparticles. Noble metal decorated tungsten oxide nanostructure could be an excellent candidate for photocatalysis, gas sensing and gasochromic applications. Finally, the gasochromic behavior of the synthesized samples was investigated by H2 and O2 gases bubbling into the produced colloidal Au/WO3 nanoparticles. Synthesized colloidal nanoparticles show excellent coloration contrast (∼80%) through NIR spectra. © 2015 Elsevier B.V. All rights reserved.

Namadmalan A.,Jundi-Shapur University of Technology
IEEE Transactions on Power Electronics | Year: 2016

This paper presents power and frequency tuning loops based on fundamental harmonic operation (FHO) and third harmonic operation (THO) for inductive power transfer (IPT) systems. THO is an effective solution for applications requiring high-frequency power supply with low voltage gains, e.g., low-voltage contactless battery chargers. Moreover, it can reduce the switching losses and increase the net efficiency of IPT systems in light-load conditions. Compared to conventional methods, such as phase-locked-loop (PLL) circuits, the proposed methods are less affected by misalignments and instantly track the resonant frequency. Hence, they can be utilized in self-switched capacitor and variable coupling applications. In addition, the new tuning systems can switch between THO and FHO modes for different loadings, voltage gains, and couplings conditions, e.g., dynamic powering of different moving pickups. To show the performance of the new tuning loops, laboratory prototypes with switching frequency of 20-50 kHz are implemented based on half-bridge and full-bridge inverters. © 1986-2012 IEEE.

Haghighi A.,Shahid Chamran University | Keramat A.,Jundi-Shapur University of Technology
Journal of Hydroinformatics | Year: 2012

Uncertain parameters in the transient analysis of pipe networks lead to uncertain responses. Typical uncertainties are nodal demand, pipe friction coefficient and wave speed, which not only are imprecise in nature but also change significantly over time. Exploiting the fuzzy set theory and a simple scheme of the simulated annealing method, a conceptual model is developed. It can take into account the uncertainties of conventional transient analysis. This model helps designers of pipe systems in finding out the extent to which uncertainties in the inputs can spread to the transient highest and lowest pressures. A real piping system is analyzed herein as the case study. The results show that the transient extreme pressures can be highly affected by the uncertainties. © IWA Publishing 2012.

Khamooshi R.,Jundi-Shapur University of Technology | Namadmalan A.,Jundi-Shapur University of Technology
IET Power Electronics | Year: 2016

This study presents a new solution for harmonic optimisation of multi-level inverters using variable DC sources. The new approach is based on converter utilisation ratio consideration for total harmonic distortion (THD) minimisation. In the proposed solution, switch utilisation ratio (SUR) is introduced as an indication of efficient operation of multi-level converters and is maximised in the final THD minimisation objective functions for both phase and line-line voltages. According to the calculated formula, by SUR maximisation, the DC-link voltages of the cells are minimised which is essential for medium- and high-voltage applications. Alterable DC sources are also considered as degrees of freedom in the final target functions which results in feasible solution for the entire range of the modulation indices. In order to investigate the proposed technique, the simulations are performed for 5-, 7-, 9- and 11-level cascaded H-bridge inverters. Finally, experimental results validate the effectiveness of the suggested scheme for five- and seven-level inverters. © The Institution of Engineering and Technology 2016.

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