A Novel Intelligent Control System Design for Water BathTemperature Control

Abstract: In this paper a neuro-fuzzy controller (NFC) for temperaturecontrol of a water bath system is proposed.A five layer neural network is used to adjust input and output parameters of membership function in a fuzzy logic controller. The hybrid learning algorithm is used for training this network. The simulation results show that the proposedcontroller has good set point tracking and disturbance rejectionproperties. Also it is robust against changes in the systemparameters. It is also superior to the conventional PID controller

Stability Analysis and Control of DFIG Based Wind Turbine Using FBC Strategy

Doubly fed induction generator has numerous advantages in wind power generation over other types of generators. Once a DFIG is subjected to a large voltage dip, a large rotor voltage induces in the rotor windings. This leads to a large transient current in rotor circuit and the dc-link overvoltage, and may block power electronic converter operation. This paper first discusses dynamic modeling of DFIG wind turbines with the stator flux orientation. Then, by small signal analysis, it is found that the dynamic behavior of the DFIG based WT during voltage dip, is strongly affected by the stator dynamics. Next, a nonlinear control strategy based on flatness is proposed to improve the DFIG transient performance. The main interest of this control method is the possibility to define the behavior of the state variable system in the steady state as well as in transients. Since the DFIG electrical dynamics are nonlinear; better control performance is achieved with nonlinear control, compared with the linear control scheme. The proposed approach stabilizes the stator dynamics through rotor and grid side filter voltage control. The results of time domain simulations validate the effectiveness the nonlinear control strategy during voltage dip of generator terminal

Structural, optical and thermal characteristics of GeO2-PbO-SrO-AlF3-MgF2 glasses

In the presented work, the structural, optical and thermal characteristics of GeO2-PbO-SrO-AlF3-MgF2 glasses have been investigated. In this regard, different germanate glasses containing of PbO, SrO, MgF2 and AlF3 were prepared by conventional melt quenching technique between two steel sheets. The produced samples were characterized using X-ray diffraction, differential thermal calorimetry, Fourier transform infrared and UV-Vis spectroscopy. Based on results, the glass-forming ability and thermal stability of GeO2-PbO glasses increase by replacement of PbO with SrO in glass composition. This replacement has negligible effects on optical properties of prepared glasses and the values of Eg°pt and EU of GeO2-PbO-SrO glassy system are in the range of 2.98–3.02 and 0.27–0.28 eV, respectively. In contrast, the optical properties, overall transparency, glass-forming ability and thermal stability of GeO2-PbO-SrO glasses decrease by replacement of PbO with MgF2 and AlF3

Structural and Magnetic Characteristics of Fe72-xCoxCr28 (10<X<22) Microcrystalline Alloys Prepared by Casting

In the present study, the structural and magnetic characteristics of Fe-Co-Cr system, with 28 at. % of Cr content, during casting, solutioning and thermo-magnetic treatment has been investigated. Based on results, the formation of single α-phase solid solution in the Fe72-xCoxCr28 (10<xThe Co content had negligible effects on magnetic characteristics of Fe62Co10Cr28, Fe60Co12Cr28 and Fe58Co14Cr28 alloys. Fe72-xCoxCr28 (10<x with a constant Cr content of about 28 at. %, were outside the miscibility gap in the equilibrium phase diagram, and therefore TMT had no effect on the final magnetic properties.</x</

Magnetic Characteristics of Nanocrystalline Co78Zr17B2Si1W2 Alloy Formed by Melt Spinning and Subsequent Annealing

Investigation the structural and magnetic properties of nanocrystalline Co78Zr17B2Si1W2 alloy during melt spinning and annealing processes were the main goal of this study. In this regard, samples were prepared using vacuum induction melting, melt spinning and subsequent annealing. The specimens were evaluated using X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), differential scanning calorimetry (DSC) and vibrating sample magnetometer (VSM). Based on results, nanocrystalline Co5Zr single phase with hard magnetic properties (Ms=29.5 emu/g and Hc=2.7 kOe) successfully formed during melt spinning process (at wheel speed of 40 m.s-1). The coercivity value of rapid solidified sample increased to about 3.2 kOe during annealing process up to 400°C. However, more increasing in annealing temperature lead to the transformation of non-equilibrium magnetic Co5Zr phase to stable Zr2Co11 phase, which has distractive effects on final magnetic properties

Effects of sound pillow in the treatment of stuttering and cognitive phonemes impairment in children

Introduction:Verbal language is Fundamental component for expressing ideas, social interaction and understanding educational materials. Effective communications require verbal language skills. Sound pillows may partly address the children with behavior problems. The purpose of this study was assessing the effect of educational sound pillow in the treatment of stuttering and cognitive phonemes impairment in children. Methods:This is a clinical trial study in which the statistical community, including pre-school children to children who finish primary school in Shahrekord who referring to pediatric psychiatric clinic for treatment. Twenty-seven Children with stuttering randomly assigned to control group (13 children who will treated with speech therapy) and case group (14 children who will treat with speech therapy and sound pillow). Tthirty-three children with cognitive phonemes impairment randomly assigned to control group (17 children who will treated with speech therapy) and case group (16 children who will treat with speech therapy and sound pillow). Group therapy was hold twice a week, each session for forty minutes in which children treated with speech therapy techniques. In case group in addition to speech therapy sound pillow was used, three sessions a week each meeting for half an hour (15 minutes at the beginning of sleep and 15 minutes at the end of sleep) for a month. Intensity of abnormalities was measured before and after treatment. Data analysis was done by SPSS software with Wilcoxon signed rank tests and Mannwithny test. Result:Severity of Stuttering and cognitive phonemes impairment in both groups were similar before treatment (P>0/05). Significant decrease in the severity of stuttering and cognitive phonemes impairment was occurred after treatment in both groups (P0/05).In other words, adding sound pillow had no effects on the treatment of stuttering and cognitive phonemes impairment. Discussion:Adding sound pillow to conventional treatment (speech therapy) had no effects on the treatment of stuttering and cognitive phonemes impairment

Structural, optical and thermal characteristics of GeO₂-PbO-SrO-AlF₃-MgF₂ glasses

<p>In the presented work, the structural, optical and thermal characteristics of GeO₂-PbO-SrO-AlF₃-MgF₂ glasses have been investigated. In this regard, different germanate glasses containing of PbO, SrO, MgF₂ and AlF₃ were prepared by conventional melt quenching technique between two steel sheets. The produced samples were characterized using X-ray diffraction, differential thermal calorimetry, Fourier transform infrared and UV-Vis spectroscopy. Based on results, the glass-forming ability and thermal stability of GeO₂-PbO glasses increase by replacement of PbO with SrO in glass composition. This replacement has negligible effects on optical properties of prepared glasses and the values of <i>E_g°^pt</i> and <i>E_U</i> of GeO₂-PbO-SrO glassy system are in the range of 2.98–3.02 and 0.27–0.28 eV, respectively. In contrast, the optical properties, overall transparency, glass-forming ability and thermal stability of GeO₂-PbO-SrO glasses decrease by replacement of PbO with MgF₂ and AlF₃.</p

Synthesis, microstructure, magnetic and electromagnetic behavior of graphene oxide/hexagonal barium ferrite aerogel nanocomposites within the frequency range of 1–18 GHz

The fabrication of lightweight graphene oxide aerogel (GOA) composites with barium ferrite (BF) nanoparticles is investigated in this study as a method of shielding electronic and telecommunication equipment from electromagnetic radiation. The effects of various weight percentages of barium ferrite nanoparticles on the microstructure, phase, magnetic characteristics, and wave absorption were investigated. The XRD, FTIR, Raman spectroscopy, X-ray Photoelectron spectroscopy (XPS), thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC), FESEM, and vibrational magnetometry (VSM) and the vector network analyzer (VNA) were used to characterize the sample.Results show that barium ferrite nanoparticles had a saturation magnetization of 42.94 emu/g, whereas graphene oxide aerogel composite containing 67 wt% of barium ferrite nanoparticles had a saturation magnetization of 29 emu/g. The Coercivity of the composite rose when the amount of barium ferrite nanoparticles was reduced. Within the matched frequency of 12.1 GHz and an effective absorption bandwidth (RL < −10 dB) of 2.6 GHz, the graphene aerogel nanocomposite sample with a thickness of 4 mm and 40 wt% of barium ferrite nanoparticles had the highest level of reflection loss (−43 dB)