A fuzzy filter for improving the quality of the signal in adaptive-network-based fuzzy inference systems (ANFIS)

This study is addressed to improve the quality of the signal of the Adaptive-Network based Fuzzy Inference System (ANFIS) reducing the level of fluctuations in the output due to periodical disturbances. The fuzzy filter computes the disturbances as periodic signals with two components, one at high frequency and another at low frequency. It was incorporated in the layer 0 of the network reducing iteratively effectively the heavy noise.     

Assessment of the effects of rice husk ash particle size on strength,water permeability and workability of binary blended concrete

This study develops the compressive strength, water permeability and workability of concrete by partial replacement of cement with agro-waste rice husk ash. Two types of rice husk ash with average particle size of 5 micron (ultra fine particles) and 95 micron and with four different contents of 5%, 10%, 15% and 20% by weight were used. Replacement of cement up to maximum of 15% and 20% respectively by 95 and 5 μm rice husk ash, produces concrete with improved strength. However, the ultimate strength of concrete was gained at 10% of cement replacement by ultra fine rice husk ash particles. Also the percentage, velocity and coefficient of water absorption significantly decreased with 10% cement replacement by ultra fine rice husk ash. Moreover, the workability of fresh concrete was remarkably improved by increasing the content of rice husk ash especially in the case of coarser size. It is concluded that partial replacement of cement with rice husk ash improves the compressive strength and workability of concrete and decreases its water permeability. In addition, decreasing rice husk ash average particle size provides a positive effect on the compressive strength and water permeability of hardened concrete but indicates adverse effect on the workability of fresh concrete.     

Noncontact conveyance of conductive plate using omni-directional magnet wheel

A magnet wheel is chosen as the driving method to transfer a conductive plate without mechanical contact in space, due to its high force density. When permanent magnets (hereafter PMs) constituting the magnet wheel rotate below the conductive plate, not only a repulsive type of normal force but also a traction torque is generated on the plate. To utilize the torque as a thrust force, the magnetic fields from PMs are covered partially using a magnetic shield plate. So, in-plane positions of the conductive plate are controlled by turning the shield plate opened partially. In this paper, the operating principle of the noncontact conveyance system using a magnet wheel is discussed, including experimental verification. Specially, the resulting force from the suggested magnet wheel is AC force with oscillation, but it can be minimized through varying entry or exit shape of the open area of the magnetic shield plate.     

A thermal model of friction stir welding applied to Sc-modified Al–Zn–Mg–Cu alloy extrusions

A thermal model of friction stir welding is presented that proposes an energy-based formulation of the Johnson–Cook plasticity model in order to account for heat generation due to plastic deformation. The proposed formulation is derived from an empirical, linear relationship observed between the ratio of the maximum welding temperature to the solidus temperature of the alloy and the welding energy. The thermal model is applied to Sc-modified Al–Zn–Mg–Cu alloy extrusions joined by friction stir welding at 225, 250, 300 and 400 RPM (all other weld parameters held constant). With the incorporation of heat generation due to plastic deformation, the thermal model accurately predicts the maximum weld temperatures and temperature profiles at the higher energy weld conditions, i.e. 300 and 400 RPM. At the lower energy welds (i.e. 225 and 250 RPM) where plastic deformation contributes a larger portion to the total heat generation, the model under-predicts the maximum weld temperatures under the tool shoulder but shows good agreement with the remaining experimental temperature data.     

Unconventional magnetism in ZnO nanorods

ABSTRACT

We report room temperature ferromagnetism in vacuum annealed ZnO nanorods. ZnO nanorods were annealed at 600°C for 6 hours in an annealing chamber with a pressure of 10^?6 Torr. Our study indicates that ZnO nanorods develop room temperature ferromagnetism due to the presence of oxygen vacancy defects in it. Presence of large surface area of nanorods and oxygen vacancy are mainly responsible for the observed magnetic behavior.     

Dispersion of nanoplatelets of graphite on PMMA matrix by in situ polymerisation technique

Poly(methyl methacrylate)/expanded graphite (PMMA/EG) composites were prepared by the incorporation of EG in various proportions (1%, 2%, 3%, 4% and 5%) with PMMA by in situ polymerisation technique. The polymer composites were characterised by ultraviolet–visible (UV–vis) and Fourier transform infra-red spectroscopies. The structural property of PMMA/EG nanocomposites was studied by X-ray diffraction. The scanning electron microscopy and transmission electron microscopy of synthesised composites were taken in order to study their morphological properties. The conductivity of composites was measured as function of EG concentration. It was found that conductivity of composites gradually increased with the increase in EG loading. Oxygen permeability of PMMA/EG nanocomposites was calculated and it was found that the property was reduced substantially with rise of EG proportion. The thermal stability of PMMA/EG nanocomposites was improved by dispersion of EG with PMMA matrix.     

Dielectric and electrical properties of 0.5(BiGd0.05Fe0.95O3)-0.5(PbZrO3) composite

The 0.5(BiGd_0.05Fe_0.95O₃)-0.5(PbZrO₃) composite was synthesized by means of a high temperature solid-state reaction technique using high purity ingredients. Preliminary X-ray structural analysis confirms the formation of the composite. The dielectric constant and loss tangent have been studied. The impedance parameters have been measured using an impedance analyzer in a wide range of frequency (10²–10⁶ Hz) at different temperatures. The Nyquist plot suggests the contribution of bulk effect only and the bulk resistance decreases with a rise in temperature. Electrical impedance confirms the presence of grain effect and hopping mechanism in the electrical transport of the material. The dc conductivity increases with a rise of temperature. The frequency variation of ac conductivity shows that the compound obeys Jonscher’s universal power law and from Jonscher’s power law fit confirms the Small Polaron (SP) tunneling effect. Temperature dependence of dc and ac conductivity indicates that electrical conduction in the material is a thermally activated process.     

Low noise wide bandgap SiC based IMPATT diodes at sub-millimeter wave frequencies and at high temperature

We have presented a comparative account of the high frequency prospective as well as noise behaviors of wide-bandgap 4H-SiC and 6H-SiC based on different structures of IMPATT diodes at sub-millimeter-wave frequencies up to 2.18 THz. The computer simulation study establishes the feasibility of the SiC based IMPATT diode as a high power density terahertz source. The most significant feature lies in the noise behavior of the SiC IMPATT diodes. It is noticed that the 6H-SiC DDR diode shows the least noise measure of 26.1 dB as compared to that of other structures. Further, it is noticed that the noise measure of the SiC IMPATT diode is less at a higher operating frequency compared to that at a lower operating frequency.     

Nano boron nitride laminated poly(ethyl methacrylate)/poly(vinyl alcohol) composite films imprinted with silver nanoparticles as gas barrier and bacteria resistant packaging materials

Herein, nano boron nitride (BN) laminated poly(ethyl methacrylate) (PEMA)/poly(vinyl alcohol) (PVA) nanocomposite films are fabricated by using a simple in situ polymerization technique with incorporation of silver nanoparticles (Ag NPs). Structural investigations of PEMA/PVA/Ag@BN nanocomposite thin films are carried out by Fourier-transform infrared spectroscopy, dynamic light scattering, X-ray diffraction analysis, ¹H nuclear magnetic resonance, ¹³C nuclear magnetic resonance, and mass spectrometry. The change in morphology of PEMA/PVA matrix due to the reinforcement of BN platelets are identified by electron microscopic studies. The unique tortuous paths are achieved by the dispersion of BN platelets by which gas penetration is restricted with enhancing the barrier properties of the material by 6.5 folds at 5 wt% BN content as compared with neat PEMA/PVA. Acid and alkali resistant along with biodegradability behavior of as-synthesized nanocomposites are studied. From limiting oxygen index (LOI) results, it is found that the prepared materials are fire retardant in nature owing to effective reinforcement of BN layers. Antibacterial activities of PEMA/PVA/Ag@BN nanocomposite are studied by Xanthomonas citri or axonopodis pv. Citri, Escherichia coli, and Xanthomonas oryzae pv. Oryzae because of Ag NPs reinforcement. The substantial improvements in gas barrier, fire retardant, and antibacterial properties enable the materials for packaging application.