Design of an Adaptive Backstepping Controller for Doubly-Fed Induction Machine Drives

Dehkordi, Behzad Mirzaeian,Payam, Amir Farrokh,Hashemnia, Mohammad Naser,Sul, Seung-Ki The Korean Institute of Power Electronics 2009 JOURNAL OF POWER ELECTRONICS Vol.9 No.3

In this paper, a nonlinear controller is proposed for Doubly-Fed Induction Machine (DFIM) drives. The nonlinear controller is designed based on an adaptive backstepping control technique, using a fifth order model of an induction machine in the synchronous d & q axis rotating reference frame, whose d axis coincides with the space voltage vector of the main AC supply, and using the rotor current and stator flux components as state variables. The nonlinear controller can perfectly track the torque reference signal measured in the stator terminals under the condition of unity power factor regulation, in spite of the stator and rotor resistance variations. In order to make the drive system capable of operating in the motoring and generating modes below and above the synchronous speed, two level Space-Vector PWM (SV-PWM) back-to-back voltage source inverters are employed in the rotor circuit. It is confirmed through computer simulation results that the proposed control approach is effective and valid.

The antinociceptive effect of artemisinin on the inflammatory pain and role of GABAergic and opioidergic systems

Dehkordi, Faraz Mahdian,Kaboutari, Jahangir,Zendehdel, Morteza,Javdani, Moosa The Korean Pain Society 2019 The Korean Journal of Pain Vol.32 No.3

Background: Pain is a complex mechanism which involves different systems, including the opioidergic and GABAergic systems. Due to the side effects of chemical analgesic agents, attention toward natural agents have been increased. Artemisinin is an herbal compound with widespread modern and traditional therapeutic indications, which its interaction with the GABAergic system and antinoniceptive effects on neuropathic pain have shown. Therefore, this study was designed to evaluate the antinociceptive effects of artemisinin during inflammatory pain and interaction with the GABAergic and opioidergic systems by using a writhing response test. Methods: On the whole, 198 adult male albino mice were used in 4 experiments, including 9 groups (n = 6) each with three replicates, by intraperitoneal (i.p.) administration of artemisinin (2.5, 5, and 10 mg/kg), naloxone (2 mg/kg), bicuculline (2 mg/kg), saclofen (2 mg/kg), indomethacin (5 mg/kg), and ethanol (10 mL/kg). Writhing test responses were induced by i.p. injection of 10 mL/kg of 0.6% acetic acid, and the percentage of writhing inhibition was recorded. Results: Results showed significant dose dependent anti-nociceptive effects from artemisinin which, at a 10 mg/kg dose, was statistically similar to indomethacin. Neither saclofen nor naloxone had antinociceptive effects and did not antagonize antinociceptive effects of artemisinin, whereas bicuculline significantly inhibited the antinocicptive effect of artemisinin. Conclusions: It seems that antinocicptive effects of artemisinin are mediated by $GABA_A$ receptors.

Optimal Design of a Damped Input Filter Based on a Genetic Algorithm for an Electrolytic Capacitor-less Converter

Dehkordi, Behzad Mirzaeian,Yoo, Anno,Sul, Seung-Ki The Korean Institute of Power Electronics 2009 JOURNAL OF POWER ELECTRONICS Vol.9 No.3

In this paper an optimal damped input filter is designed based on a Genetic Algorithm (GA) for an electrolytic capacitor-less AC-AC converter. Sufficient passive damping and minimum losses in passive damping elements, minimization of the filter output impedance at the filter cut-off frequency, minimization of the DC-link voltage and input current fluctuations, and minimization of the filter costs are the main objectives in the multi-objective optimization of the input filter. The proposed filter has been validated experimentally using an induction motor drive system employing an electrolytic capacitor-less AC-AC converter.

On Some Properties of Riemannian Manifolds with a Generalized Connection

Dehkordy, Azam Etemad Department of Mathematics 2016 Kyungpook mathematical journal Vol.56 No.4

In this paper we study some properties of submanifolds of a Riemannian manifold equipped with a generalized connection $\hat{\nabla}$. We also consider almost Hermitian manifolds that admits a special case of this generalized connection and derive some results about the behavior of this manifolds.

SOME NEW CHARACTERIZATIONS OF QUASI-FROBENIUS RINGS BY USING PURE-INJECTIVITY

Moradzadeh-Dehkordi, Ali Korean Mathematical Society 2020 대한수학회보 Vol.57 No.2

A ring R is called right pure-injective if it is injective with respect to pure exact sequences. According to a well known result of L. Melkersson, every commutative Artinian ring is pure-injective, but the converse is not true, even if R is a commutative Noetherian local ring. In this paper, a series of conditions under which right pure-injective rings are either right Artinian rings or quasi-Frobenius rings are given. Also, some of our results extend previously known results for quasi-Frobenius rings.

Horizontal magnetovariational responses in geothermal exploration: synthetic model studies

Banafsheh Habibian Dehkordi,Mansoure Montahaei 한국지질과학협의회 2016 Geosciences Journal Vol.20 No.6

Horizontal magnetic inter-station transfer functions, which are less distorted by near surface inhomogeneities and more sensitive to the deep targets, have been incorporated with other magnetotelluric data sets to delineate the electrical conductivity distribution in geothermal zones. Geothermal settings composed of salty fluid saturated faults and fractures, and hydrothermal alterations show a wide variation of the bulk resistivity. This makes electromagnetic methods, particularly magnetotellurics which is able to detect the geoelectric structures of deep targets, ideal techniques for the exploration of geothermal regions. In this research, the horizontal magnetovariational data are combined with other magnetotelluric transfer functions and their capabilities for improving the electrical conductivity structure obtained from 2D inversion process are examined. To this end, several synthetic models-representative of the conductivity changes in geothermal fields or conceptual modelshave been utilized. The results from two-dimensional (2D) inversion confirm the effectiveness of horizontal magnetic tensor as a part of the transfer functions, especially for the detection of deep conductive features.

Characterization of Microsatellites and Development of SSR Markers in Pomegranate

Mehranna Koohi-Dehkordi,Badraldin Ebrahim Sayed-Tabata,Masoud Bahar 한국원예학회 2006 한국원예학회 기타간행물 Vol.- No.-

Effect of ammonium nitrate on microstructure and permeability characteristics of tubular alumina support using slip casting fabrication method

Nooshin Heydarian Dehkordi,Masoud Shayesteh,Mahdi Shafiee Afarani,Abdolreza Samimi 한양대학교 세라믹연구소 2013 Journal of Ceramic Processing Research Vol.14 No.4

Tubular porous alumina supports were manufactured by slip casting process for microstructure and permeability study. In this regard, effect of ammonium nitrate addition in presence of Tiron dispersant on slurry stability and microstructure of samples was specifically studied. Furthermore, rejection of ions dissolved in water as well as permeation flux of water was evaluated considering ionic conductivity, total dissolved solids (TDS) and flow rate analyses. Results showed that the addition of ammonium nitrate and Tiron led to more stable initial slurries before slip casting and more porous tubular supports. In this case, the water flux and permeability through the supports were increased considerably. However, as expected, the ions rejection was not affected comparatively for the supports with and without ammonium nitrate.

The investigation of the combined effects of gamma irradiation and environmental manipulation on mortality and sterility of Rhyzopertha dominica (Fabricius) (Coleoptera: Bostrichidae)

Shohreh Asgarian Dehkordi,Mehrdad Ahmadi,BijanHatami 한국응용곤충학회 2018 Journal of Asia-Pacific Entomology Vol.21 No.4

With respect to the limitations use of methyl bromide and phosphine, employing ionizing radiation to control stored product pests has attracted great attention. The aim of this study is the investigation of the combined effects of gamma irradiation as viable alternatives to synthetic insecticides and environmental management on mortality and sterility of Rhyzopertha dominica (Fabricius) in a wheat cultivar (Gascogen). The effect of doses range from 30 to 2000 Gy gamma irradiation in combination with manipulation of temperature (15, 21, 27 and 32 °C) and relative humidity (20%, 50%, 65% and 85%) on 5–10 days old adults of R. dominica in Gascogen cultivar of wheat were explored. The experiments were repeated three times and conducted in The Nuclear Agriculture Research School in Karaj and laboratory of shahid steki silo in shahre-kord. Probit analysis revealed that both temperature and relative humidity had combined effects when used with gamma irradiation. The lowest doses of gamma ray required to kill 25% (14.2 Gy) and 50% (610.8 Gy) of the population (LD 25 and LD 50 ) were recorded at 21 °C and 85% relative humidity respectively. The low dose for 99% mortality (LD 99 ; 2386.7 Gy) was recorded for beetles maintained at 21 °C and 50% relative humidity. The effect of temperature (15, 21, 27 and 32 °C) on sterility caused by gamma irradiation was also investigated. The results showed that the F 1 generation emerged only when the beetles were treated with doses of 0–100 Gy at 32 °C and 0–70 Gy at 27 °C. These results indicate that temperature and relative humidity play an important role in the susceptibility of the lesser grain beetle to gamma irradiation. The results suggest that controlling the efficiency of gamma radiation through environmental control allows the use of low doses of gamma radiation that have a less harmful effect on human health, non-target organisms and seed agronomic features.

Solids Mixing Intensifi cation in Tapered Fluidized Beds with an Inlet Jet: Experimental Validation and CFD Simulation

Asghar Molaei Dehkordi 한국화학공학회 2024 Korean Journal of Chemical Engineering Vol.41 No.1

In this article, the intensifi cation of solids mixing in tapered fl uidized beds equipped with an inlet jet and varying apex angles (2.86°, 5.71°, and 8.53°) has been investigated. In this regard, a particle segregation number (PSN) and multi-fl uid modeling (MFM) approach were employed to analyze the mixing process. The study utilized solid mixtures composed of particles with a density of 2500 kg/m 3 and diameters of 240 and 510 μm. Simulation results were validated against our experimental data obtained using a small tapered bed without an inlet jet and those obtained using a larger tapered bed with an inlet jet, as Huilin et al. (2003) reported. This validation demonstrates satisfactory agreement between the simulation results and experimental data. The solids mixing process in a columnar fl uidized bed was found to resemble that in a tapered bed with an apex angle of 2.86°. Increasing the apex angle leads to a larger equilibrium mixing value. In addition, the infl uences of inlet jet velocity and nozzle diameter on the solids mixing process were investigated. The simulation results indicated that higher inlet jet velocities and larger nozzle diameters enhance the equilibrium mixing index value. Notably, inlet jet velocities of 0.7 and 0.8 m/s exhibited three distinct solids mixing stages: rapid, slow, and equilibrium, whereas higher jet velocities only involved rapid and equilibrium mixing stages. Moreover, this study further examined how the initial arrangement of solid particles aff ects the mixing index, providing valuable insights into optimizing the solids mixing process. Furthermore, the present work sheds light on the factors infl uencing the mixing of solids in tapered fl uidized beds, off ering valuable insights for further research and industrial applications.