Analysis of acoustic emission signals at austempering of steels using neural networks

Bearing steel 100CrMnSi6-4 and tool steel C105U were used to carry out this research with the steels being austempered to obtain a martensitic-bainitic structure. During the process quite a large number of acoustic emissions (AE) were observed. These signals were then analysed using neural networks resulting in the identification of three groups of events of: high, medium and low energy and in addition their spectral characteristics were plotted. The results were presented in the form of diagrams of AE incidence as a function of time. It was demonstrated that complex transformations of austenite into martensite and bainite occurred when austempering bearing steel at 160 °C and tool steel at 130 °C respectively. The selected temperatures of isothermal quenching of the tested steels were within the area near to MS temperature, which affected the complex course of phase transition. The high activity of AE is a typical occurrence for martensitic transformation and this is the transformation mechanism that induces the generation of AE signals of higher energy in the first stage of transition. In the second stage of transformation, the initially nucleated martensite accelerates the occurrence of the next bainitic transformation.     

Tailoring magnetic anisotropy gradients by ion bombardment for domain wall positioning in magnetic multilayers with perpendicular anisotropy

Graded anisotropy magnetic materials possess a coercive field changing laterally with position. A simple fabrication procedure to produce such an anisotropy gradient in a polycrystalline Au/Co layer system without lateral thickness variation and with perpendicular magnetic anisotropy, prototypical for a large variety of thin film systems, is shown. The procedure uses light-ion bombardment without the use of a mask. Magnetization reversal in this polycrystalline layer system takes place by unidirectional movement of a single domain wall only in regions with larger anisotropies and anisotropy gradients. In this anisotropy/anisotropy gradient regime, the domain wall is oriented perpendicular to the coercive field gradient, and it can be positioned along the gradient by an appropriate magnetic field pulse. For smaller anisotropies/anisotropy gradients, the natural anisotropy fluctuations of the polycrystalline layer system induce magnetization reversal dominated by domain nucleation.

PACS

75.30.Gw; 75.70.Cn; 75.60.Ch     

Investigations of chromium (VI) ion sorption and reduction on strongly basic anion exchanger

Removal of chromium(VI) ions and their reduction were studied on the anion exchanger Dowex PSR-2 in the pH range from 1.5 to 10. The parameters of Cr(VI) sorption process on the anion exchanger were calculated based on the most popular isotherm models such as: Freundlich, Langmuir, Temkin, and Dubinin–Radushkevich (D-R). The Langmuir isotherm was the most appropriate to describe Cr(VI) sorption. The Cr(VI) uptake by Dowex PSR-2 was found to follow the pseudo-second-order rate kinetics. Reduction of chromium(VI) in the pH range 1.5–10 was observed using the HPLC-ICP-MS (high-performance liquid chromatography–inductively coupled plasma-mass spectrometry) method. Oxidation of tri-n-butyl quaternary ammonium groups during the chromate (VI) removal process was observed.     

A methodology for implementation of mobile robot in adaptive manufacturing environments

With the rapid development of technologies, many production systems and modes has been advanced with respect to manufacturing, management and information fields. The paper deals with the problem of the implementation of an autonomous industrial mobile robot in real-world industrial applications in which all these fields are considered, namely mobile robot technology, planning and scheduling and communication. A methodology for implementation consisting of: a mobile robot system design (Little Helper prototype), an appropriate industrial application (multiple-part feeding), an implementation concept for the industrial application (the Bartender Concept), a mathematical model and a genetic algorithm-based heuristic is proposed. Furthermore, in order for the mobile robot to work properly in a flexible (cloud-based) manufacturing environment, the communications and exchange of data between the mobile robot with other manufacturing systems and shop-floor operators are addressed in the methodology. The proposed methodology provides insight into how mobile robot technology and abilities contribute to cloud manufacturing systems. A real-world demonstration at an impeller production line in a factory and computational experiments are conducted to demonstrate the effectiveness of the proposed methodology.     

Conditional entropic uncertainty relations for Tsallis entropies

The entropic uncertainty relations are a very active field of scientific inquiry. Their applications include quantum cryptography and studies of quantum phenomena such as correlations and non-locality. In this work we find entanglement-dependent entropic uncertainty relations in terms of the Tsallis entropies for states with a fixed amount of entanglement. Our main result is stated as Theorem 1. Taking the special case of von Neumann entropy and utilizing the concavity of conditional von Neumann entropies, we extend our result to mixed states. Finally we provide a lower bound on the amount of extractable key in a quantum cryptographic scenario.     

Image simulation using Monte Carlo methods: Electron beam and detector characteristics

The rapid increase of computer speed allows using Monte Carlo simulation procedures for the analysis of complicated structures not only in a line scan mode but also in a three-dimensional approach similar to the scanning procedure in a scanning electron microscope. Simulation of image formation is a vital link in performing image analysis to obtain precise measurements, to provide the necessary connection between image parameters and structural dimensions, and to reflect important microscope beam and detector parameters. Monte Carlo simulation based on a single-scattering procedure was used for backscattered electron image simulation of three-dimensional multilayer and multielement structures. The procedure takes into account the effect of a solid state detector's electrical and angular characteristics and the effect of the electron beam dimensions on the image quality and artifacts.     

Diffusion of chromium,manganese, and iron in MnCr<Subscript>2</Subscript>O<Subscript>4</Subscript> spinel

As a result of the oxidation of chromium (Cr)-manganese (Mn) steels, a multilayer scale is formed. The intermediate layer of this scale is composed of MnCr₂O₄ spinel, and the outer layer is composed of MnO. The aim of the current study is to examine self-diffusion processes in MnCr₂O₄ spinel by a tracer method. In experiments, the radioisotopes ⁵⁴Mn, ⁵¹Cr, and ⁵⁹Fe were used. The serial sectioning method was applied for the simultaneous evaluation of diffusion rates of Cr, Mn, and iron (Fe) in MnCr₂O₄ spinel at 1173 K under a pressure of 10⁵ Pa in SO₂ containing 10 Pa O₂. This spinel was obtained by a modified sol-gel method from metal nitrates (R. Gajerski and Z. Zurek, personal communication, 14.04.2004). It was found that the dominant mechanism of Mn transport in the studied samples is a volume diffusion, while Cr and Fe are transported mainly through the high-diffusivity paths.     

Toughening of Semicrystalline and Amorphous Polylactide with Atactic Polyhydroxybutyrate

Biodegradable and biocompatible blends of polylactide with atactic poly([R,S]-3-hydroxybutyrate) were studied. Cold-crystallized blends exhibit lamellar–spherulitic morphology. Lamellae thickness and crystallinity, controlled by conditions of annealing, surprisingly do not depend on blend composition. In contrast, due to partial miscibility, the glass transition, cold crystallization, and melting temperatures depend on composition. Mechanical performance of polylactide, including drawability and toughness, is improved in both amorphous and semicrystalline blends. The main toughening mechanism identified was cavitation of atactic poly([R,S]-3-hydroxybutyrate), initiating multiple crazing of polylactide. A limited shear yielding was also observed. Activity of all these mechanisms brings brittle-to-ductile transformation in blends, above 10?wt% of atactic poly([R,S]-3-hydroxybutyrate).     

Effect of Inoculation with Probiotics and Ageing Time on Selected Functional Properties and Oxidation of Proteins in Dry-Cured Pork Loins

The effect of inoculation with a probiotic strain Lactobacillus casei ?OCK 0900 on changes in selected functional properties and protein oxidation of dry-cured pork loins during ageing was studied. The protein carbonyls content tended to increase significantly (p < 0.05) throughout ageing to reach a maximum level which was approximately two-fold the initial level in both samples. No statistically significant differences (p < 0.05) in carbonyl content were found between the control sample and sample inoculated with L. casei. The passage of ageing time was coupled with a statistically significant (p < 0.05) increase in the trichloroacetic acid soluble peptides concentration in examined loins. Inoculation with a probiotic strain did not have an influence on trichloroacetic acid soluble peptides concentration during the shortest ageing period. Results of measurements carried out for the control sample after 21 and 28 days of ageing were significantly lower (p < 0.05) than those obtained for the sample inoculated with L. casei ?OCK 0900. Free α-amino acids content in both samples increased continuously with increasing ageing time (p < 0.05). Inoculation of loins with a probiotic strain Lactobacillus casei ?OCK 0900 resulted in significantly higher peptides and free amino acids content. These differences might affect their organoleptic characteristics that need further investigations.     

Hydrodynamics of the Pulsed Fluid Bed with Cyclically Relocated Gas Stream with Lengthwise Pulsation

The hydrodynamics studies of the pulsed fluid bed (PFB) with lengthwise pulsation are reported in the article. The pulsed fluid bed with lengthwise pulsation is a modification of the classical PFB. In the PFB dryer with lengthwise pulsation, the disk gas distributor cyclically relocates the gas stream to each pressure chamber situated under the grid, parallel to the lengthwise axis of the main chamber. Such structure of a dryer is more compact than the previous ones. The operation range, pressure drops, and bed structure of a new system with lengthwise pulsation have been shown.