An end-quality assessment system for electronically commutated motors based on evidential reasoning

Automatic end-quality assessment is a mean that helps reaching zero-fault products at the end of the manufacturing process. In this paper we present a system for assessing the quality of electronically commutated motors. The system consists of two major parts: feature extraction and overall quality assessment. The feature extraction part consists of signal processing algorithms tailored for mechanical fault detection. The quality assessment part, aimed for fault isolation and final quality decision, employs evidential reasoning for multi-attribute decision analysis. A prototype version of the system is validated on a test batch of 130 electronically commutated motors, demonstrating high diagnostic resolution and accuracy.     

An Analog–Digital Hardware for L-Estimate Space-Varying Image Filtering

An analog–digital hardware solution for implementation of the L-estimate space-varying filtering has been proposed. The considered filter form is based on the robust space/spatial-frequency representation and provides efficient denoising of two-dimensional signals/images corrupted by heavy-tailed noise. Moreover, for images with fast-varying details and textures, the L-estimate filtering outperforms the commonly used filters. However, it requires significant processing time, since the space/spatial-frequency representation is calculated for each pixel, on a window by window basis. Therefore, in order to make it feasible for practical applications, a fast implementation of L-estimate space-varying filtering is proposed using a combined analog–digital approach. It provides efficient real-time processing of images corrupted by strong mixed Gaussian and impulse noise.     

Synthesis,morphology, microstructure and magnetic properties of hematite submicron particles

We report on hydrothermal synthesis, plate-like morphology, microstructure and magnetic properties of hematite (α-Fe₂O₃) plate-like particles. The sample is obtained immediately after the hydrothermal process without using any template and without further heat treatment. The so-obtained sample is characterized by X-ray powder diffraction (XRPD), energy-dispersive X-ray spectroscopy (EDX), field-emission scanning electron microscope (FE-SEM), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), and superconducting quantum interference device (SQUID) magnetometer. XRPD confirms the formation of a single-phase hematite sample whereas EDX reveals that iron and oxygen are the only components of the sample. SEM, FE-SEM, TEM and HRTEM show that the sample is composed of plate-like particles. The width of the particles is ～500 nm whereas thickness is ～100 nm (aspect ratio 5:1). The HRTEM images exhibit well defined lattice fringes of α-Fe₂O₃ particles that confirm their high crystallinity. Moreover, the HRTEM analysis indicates the plate-like particles preferring crystal growth along [0 1 2] direction. Magnetic measurements display significant hysteretic behavior at room temperature with coercivity H_C = 1140 Oe, remanent magnetization M_r = 0.125 emu/g and saturation magnetization M_S = 2.15 emu/g as well as the Morin transition at T_M ～ 250 K. The magnetic properties are discussed with respect to morphology and microstructure of the particles. The results and comparison with urchin-like, rods, spherical, hexagonal, star-like, dendrites, platelets, irregular, nanoplatelets, nanocolumns and nanospheres hematites reveal that the plate-like particles possess good magnetic properties. One may conjecture that the shape anisotropy plays an important role in the magnetic properties of the sample.     

Plasma electrolytic oxidation of titanium in heteropolytungstate acids

This article is a review of our recent research of plasma electrolytic oxidation (PEO) process of titanium in heteropolytungstate acids (12-tungstosilicic acid and 12-tungstophosphoric acid). It has been detected that spatial density of microdischarges is the highest in the early stage of the PEO process, while the percentage of oxide coating area covered by active discharge sites decreases with PEO time. The elements and their ionization stages present in PEO microdischarges are identified using optical emission spectroscopy technique. The spectral line shape analysis of hydrogen Balmer line H_β (486.13 nm) indicates presence of two types of microdischarges during PEO. The discharges are characterized by relatively low electron number densities of N_e ≈ 0.8 × 10¹⁵ cm^? 3 and N_e ≈ 2.1 × 10¹⁶ cm^? 3. Oxide coatings formed by PEO process were characterized by AFM, SEM–EDX and XRD. The elemental components of PEO coatings are Ti, W and O. The oxide coatings are partly crystallized and mainly composed of WO₃ and anatase.     

Modeling and measurement of cross‐talk transmission between coupled lines

In multiwire cables, high‐frequency signals can, and do, propagate not only by direct conduction over a pair of wires the signal was inserted to but also by electromagnetic coupling between adjacent transmission lines formed out of multiple wire pairs, too. Thus, it is useful to be able to measure relevant parameters, dependent of cable geometry and isolation material, that would enable modeling of cross‐talk propagation. In this article, signal propagation between ports of two coupled lines is first theoretically analyzed using z‐parameters. Then, the physical quantities needed for calculation of z‐parameters in systems with electrically long cable sections were defined and measured, and the results were verified against measurements performed on real cables. Copyright © 2014 John Wiley & Sons, Ltd.     

Elastic liposomes-in-vehicle formulations destined for skin therapy: the synergy between type of liposomes and vehicle

Objective: The present study is focused on optimization of elastic liposomes-in-vehicle formulations in respect to drug release and formulation properties. By combining penetration potential of elastic liposomes containing high ratio of entrapped drug and physicochemical properties of vehicles, both affecting the release and texture properties, optimal formulation could be achieved.

Materials and methods: Deformable, propylene glycol-containing or conventional liposomes with hydrophilic model drug (diclofenac sodium) were incorporated into the following vehicles appropriate for skin application: a hydrogel, a cream base and derma membrane structure base cream (DMS base). Each formulation was assessed for in vitro drug release and mechanical properties.

Results and discussion: The composition and type of both liposomes and the vehicle affected the rate and amount of the released drug. The cream base exhibited the slowest release, followed by the hydrogel and DMS base. Similar release profiles were achieved with both types of elastic vesicles (deformable and propylene glycol liposomes); the slowest release was observed for conventional liposomes, regardless of the vehicle used. The drug release profiles from different liposomes-in-vehicle formulations were in agreement with the physicochemical properties of the formulations. All of the liposomes were found to be compatible with the hydrogel preserving its original textures, whereas a significant decrease in all texture parameters was observed for liposomes-in-DMS base, regardless of liposome type.

Conclusion: Propylene glycol liposomes-in-hydrogel is considered as the optimal formulation for improving skin delivery of hydrophilic drug. Further investigations involving in vivo animal studies are necessary to confirm its applicability in skin therapy.     

Effects of different culture conditions on biological potential and metabolites production in three Penicillium isolates

The genus Penicillium is well known for its importance in drug and food production. Certain species are produced on an industrial scale for the production of antibiotics (e.g. penicillin) or for insertion in food (e.g. cheese). In the present work, three Penicillium species, part of the natural mycobiota growing on various food products were selected – P. ochrochloron, P. funiculosum and P. verrucosum var. cyclopium. The objective of our study was to value these species from the point of view of production of bioactive metabolites. The species were obtained after inoculation and growth in Czapek and Malt media. Both mycelia and culture media were analyzed to monitor the production of different metabolites by each fungus and their release to the culture medium. The concentrations of sugars, organic acids, phenolic acids and tocopherols were determined. Antioxidant activity of the phenolic extracts was evaluated, as also the antimicrobial activity of phenolic acids, organic acids and tocopherols extracts. Rhamnose, xylose, fructose and trehalose were found in all the mycelia and culture media; the prevailing organic acids were oxalic and fumaric acids, and protocatechuic and p-hydroxybenzoic acids were the most common phenolic acids; γ-tocopherol was the most abundant vitamin E isoform. Generally, the phenolic extracts corresponding to the mycelia samples revealed higher antioxidant activity. Concerning the antimicrobial activity there were some fluctuations, however all the studied species revealed activity against the tested strains. Therefore, the in-vitro bioprocesses can be an alternative for the production of bioactive metabolites that can be used by pharmaceutical industry.     

Insight into the Interaction Between Carbopol® 940 and Ionic/Nonionic Surfactant

Mixtures of a cross‐linked polyacrylic acid (Carbopol^® 940) and two types of surfactants, namely anionic sodium dodecylsulfate (SDS) and nonionic Tween^® 80, were investigated by viscometry, conductometry, tensiometry, spectrophotometry, fluorimetry and scanning electron microscopy (SEM). The addition of nonionic surfactant decreased the reduced viscosity and the transmittance of the Carbopol^® polymer aqueous solutions. Furthermore, the interaction between Carbopol^® 940 and SDS was characterized by two significant concentration values: the critical aggregation concentration of SDS was particularly independent of Carbopol^® polymer concentration while the polymer saturation point of both surfactants increased with the increase in polymer content. The values of critical aggregation concentration and polymer saturation point obtained using various techniques confirmed the occurrence of Carbopol^® polymer–surfactant associations. The effect of different SDS and Tween^® 80 concentrations on the conformation of Carbopol^® 940 in aqueous solution could be explained through hydrophobic association between surfactant micelles and Carbopol^® polymer tails and through hydrogen bonding in the case of Tween^® 80. Additionally, the surfactant‐induced structural changes were confirmed in Carbopol^® 940–SDS and Carbopol^® 940–Tween^® 80 aqueous solutions by SEM measurements.     

Novel Utilization of Fly Ash for High‐Temperature Mortars: Phase Composition,Microstructure and Performances Correlation

In this study, the feasibility of using fly ash to manufacture high‐temperature mortars was investigated. The investigation was set to define preliminary characteristics of new types of mortars based on ordinary and/or refractory cement with fly ash addition, and to establish mutual correlation between thermally induced changes of mineral phases, microstructure, and final performances of the mortars. New mortars, made up of 21% cement (PC‐CEM I 42.5R/HAC‐Secar 70/71), 70% river sand, and 9% fly ash, were chemically, physically, and mechanically characterized to determine possibilities of fly ash re‐utilization for high‐temperature purposes. The fly ash samples, which originated from four different power plants, were mechanically activated. Mortars were heat‐treated up to 1300°C in a laboratory tunnel furnace with retention time 2 h. Thermal stability of crystalline phases were studied by differential thermal analysis (DTA); thermally induced changes in mineral phase composition were analyzed by XRD; and microstructure were investigated by scanning electron microscopy. Correlated results of DTA, XRD, and SEM analyses indicated initiation of sintering processes at approximately 1300°C and formation of thermally stable minerals (rankinite, gehlenite, anorthite, cristobalite). The investigation highlights a sustainable approach of using fly ash in developing ecofriendly mortars for high‐temperature application.