Nanolayer CrAlN/TiSiN coating designed for tribological applications

With the goal to produce a hard and tough coating intended for tribological applications, CrAlN/TiSiN nanolayer coating was prepared by alternative deposition of CrAlN and TiSiN layers. In the first part of the article, a detailed study of phase composition, microstructure, and layer structure of CrAlN/TiSiN coating is presented. In the second part, its mechanical properties, fracture and tribological behavior are compared to the nanocomposite TiSiN coating. An industrial magnetron sputtering unit was used for coating deposition. X-ray photoelectron spectroscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, scanning electron microscopy, and transmission electron microscopy were used for compositional and microstructural analysis. Mechanical properties and fracture behavior were studied by instrumented indentation and focused ion beam techniques. Tribological properties were evaluated by ball-on-disk test in a linear reciprocal mode. A complex layer structure was found in the nanolayer coating. The TiSiN layers were epitaxially stabilized inside the coating which led to formation of dislocations at interfaces, to introduction of disturbances in the coating growth, and as a result, to development of fine-grained columnar microstructure. Indentation load required for the onset of fracture was twice lower for the nanolayer CrAlN/TiSiN, compared to the nanocomposite TiSiN coating. This agrees very well with their mechanical properties, with H³/E² being twice higher for the TiSiN coating. However, the nanolayer coating experienced less severe damage, which had a strong impact on tribological behavior. A magnitude of order lower wear rate and four times lower steady state friction coefficient were found for the nanolayer coating.     

AI paradigms

The aim of this paper is comparative analysis of most important AI paradigms. An AI paradigm is defined as the pair composed by a concept of intelligence and a methodology in which intelligent computer systems are developed and operated. Three paradigms, the behaviourist paradigm, the agent paradigm, and the artificial life paradigm are discussed.     

Corrosion protection of aluminium in acidic chloride solutions with nontoxic inhibitors

Corrosion kinetics of 99.6% aluminium covered by a thin spontaneously formed oxide film in hydrochloric acid solution with and without the presence of substituted N-aryl pyrroles was studied using electrochemical impedance spectroscopy and quasi steady-state polarization. Measurements were performed on a rotating disc electrode in an argon-deaerated solution in the temperature range 20 to 50°C. The addition of inhibitor considerably increases overvoltage of the cathodic process (HER) and shifts Ecorr to negative potential values. The activation energy of the hydrogen evolution reaction was Ea=50±5kJmol–1 and was not affected by the presence of inhibitor. The inhibitory action occurs by -bonding between the adsorbed inhibitor molecules and the electrode surface. The electrode coverage follows the Langmuir adsorption isotherm with an adsorption equilibrium constant K=1.1–2.64×105dm3mol–1. The adsorption of organic compound prevents the adsorption of chloride ions and slow down the rate of corrosion.     

Mass transfer in aerated fermentation broths in a stirred tank reactor

The volumetric mass transfer coefficients, k_La, measured in a pilot plant (0.1 m³) and an industrial (67.5 m³) fermentor during an actual fermentation process are presented. Problems related to the estimation of the phsyical properties as well as to the correlation of experimental data and to scale up procedures are discussed. Although the scale up factor was rather high, both sets of data could be represented by single correlation. Comparison of the experimental data with several available correlations demonstrated the need for pilot plant experiments and scale up procedures, since it is almost impossible to take into account all relevant system properties.     

Formulating the template ILP consistency problem as a constraint satisfaction problem

Inductive Logic Programming (ILP) deals with the problem of finding a hypothesis covering positive examples and excluding negative examples, where both hypotheses and examples are expressed in first-order logic. In this paper we employ constraint satisfaction techniques to model and solve a problem known as template ILP consistency, which assumes that the structure of a hypothesis is known and the task is to find unification of the contained variables. In particular, we present a constraint model with index variables accompanied by a Boolean model to strengthen inference and hence improve efficiency. The efficiency of models is demonstrated experimentally.     

Limitations of a Mapping Algorithm with Fragmentation Mimics (MAFM) when modeling statistical data sources based on measured packet network traffic

Knowing the estimation of a statistical process’s parameters for measured network traffic is very important as it can then be further used for the statistical analyses and modeling of network traffic in simulation tools. It is for this reason that different estimation methods are proposed that allow estimations of the statistical processes of network traffic. One of them is our own histograms comparison (EMHC) based method that can be used to estimate statistical data-length process parameters from measured packet traffic. The main part of EMHC method is Mapping Algorithm with Fragmentation Mimics (MAFM).     

Zusätzliche Stromwärmeverluste im Läufer von Induktionsmaschinen und ihre räumliche Verteilung bei Speisung mit U-Umrichtern im Blockbetrieb

Übersicht Die zusätzlichen Stromwärmeverluste im Läufer ändern sich bei einem Drehzahlstellantrieb je nach Betriebsweise des Umrichters beträchtlich. Im Blockbetrieb ist der Gesamtverlust kaum vom Lastzustand (Schlupf) abhängig. Im Synchronismus sind die Verluste jedoch ungleichmäßig auf die einzelnen Läuferstränge oder Stäbe verteilt. Die Maxima und Minima der Stabverluste stehen im Synchronismus etwa im Verhältnis 10:1 zueinander. Die Verluste in dem am stärksten beaufschlagten Läuferstab liegen nicht wesentlich niedriger als im Bemessungsbetrieb. Die gesamten zusätzlichen Stromwärmeverluste wachsen bei konstanter Speisefrequenz quadratisch mit der Spannung. Im Feldschwächbereich nehmen sie in Abhängigkeit von der Speisefrequenz ungefähr nach der Funktion 1/^1,52 ab.

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Additional rotor I²R-losses and their spatial distribution in three-phase windings respectively rotor bars of induction motors fed from six-step U-invertors

Contents Additional rotor I²R-losses in speed variable drives with induction motors change very strongly with the operation mode of the invertor. During block-operation the sum of these additional losses is nearly independent of the load (slip). But at synchronous speed the losses are distributed very unequally among the phase windings respectively the rotor bars. The ratio of maximum to minimum bar losses is approximately 10:1. The highest ohmic loss in a bar is nearly the same as the rated bar loss. The additional rotor I²R-losses change with the square of the voltage. In the field weakening range the losses drop with the frequency approximately following the function 1/^1,52.

     

Anodic stability of electrodeposited ruthenium: galvanostatic,thermogravimetric and X-ray photoelectron spectroscopy studies

The anodic stability of an electrodeposited ruthenium electrode was measured by anodic galvanostatic polarization in 0.5 mol dm^–3 H₂SO₄ solution. The role of water and adsorbed hydroxyl groups in electrode stability was determined by means of thermogravimetric analysis. A continuous weight loss due to water removal and condensation of hydroxyl groups was detected between 120 and 430 °C. The loss of a hydrous component of the oxide layer was in direct correlation with the increase of the anodic stability. Between 430 and 480 °C a weight gain was detected on the thermogravimetric curve. It was attributed to the formation of the ruthenium oxide layer in a higher oxidative state. This finding was confirmed by X-ray photoelectron spectroscopy measurements.     

The individual ergodic theorem on the IF-events with product

The ergodic theory and particularly the individual ergodic theorem were studied in many structures. Recently the individual ergodic theorem has been proved for MV-algebras of fuzzy sets (Riečan in Czech Math J 50(125):673–680, 2000; Riečan and Neubrunn in Integral, measure, and ordering. Kluwer, Dordrecht, 1997) and even in general MV-algebras (Jurečková in Int J Theor Phys 39:757–764, 2000). The notion of almost everywhere equality of observables was introduced by Riečan and Jurečková (Int J Theor Phys 44:1587–1597, 2005). They proved that the limit of Cesaro means is an invariant observable for P-observables. In Lendelová (Int J Theor Phys 45(5):915–923, 2006c) showed that the assumption of P-observable can be omitted. In this paper we prove the individual ergodic theorem on family of IF-events and show that each P {\mathcal{P}} -preserving transformation in this family can be expressed by two corresponding P^\flat,P^\sharp {\mathcal{P}}^\flat,{\mathcal{P}}^\sharp -preserving transformations in tribe T. {\mathcal{T}}.